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    Volume 37,2021 Issue 20
    2021,37(20):1-14, DOI: 10.11975/j.issn.1002-6819.2021.20.001
    Abstract:
    Abstract: Abstract: Pesticide droplets can rebound, splash, and roll off the target surface during spraying, due mainly to insufficient wettability. The resulting environmental pollution has seriously threatened ecological stability and safety. However, the correlative mechanism of droplet deposition is still under exploration at present. It is necessary to explore the characteristics of effective droplet deposition for pest control. This study aims to review current researches on droplet deposition ranging from microdynamics of a single droplet and drift characteristics of the droplet group. The final deposition assessment and the bottleneck were also addressed, in order to clarify the research perspective of pesticide deposition. A single droplet model was essential to the impact mechanism of the droplet group because the pesticide droplets hit the target surface in the form of a single droplet during spraying. The previous reports on the deposition of the single droplet mainly contributed to the observation technologies, the influencing factors at the interface behavior of the single droplet, and the modeling of the single droplet hitting the target surface. However, the deposition behavior in the actual work depended mainly on the droplet distribution and canopy structure. There were two approaches to explore the deposition and drift characteristics in the spray field through the droplet group at present. One approach was that the observation and simulation were utilized to determine the movement of droplets in the spray field, thereby establishing the relationship between deposition behavior and amount. Another was to calculate the final deposition through actual experiments or simulation techniques, including the direct measurement of deposition on the surface of leaves, and the indirect measurement represented by the amount of drift in the air or on the ground. The research of droplet group was introduced to the distribution characteristics, deposition collection, and detection, as well as droplet group modeling. More importantly, a further combined modeling was necessary to accurately estimate the deposition behavior and the volume of deposited pesticides. The following suggestions can be drawn: 1) To establish the relationship between the single droplet and the droplet group modeling through the three-dimensional atomization field; 2) To estimate the amount of adhesion liquid after a single droplet hits the wall through image processing; 3) To explore the influence of wetted surfaces on deposition behavior; 4) To establish plant models in different growth periods. The finding can be widely expected to provide a strong reference for the research of pesticide deposition and pest control technologies.
    2021,37(20):15-22, DOI: 10.11975/j.issn.1002-6819.2021.20.002
    Abstract:
    Abstract: The selection of state number depends highly on the subjective experience in the traditional Markov Chain Monte Carlo (MCMC). However, an inappropriate value of state number can lead to a great reduction in the accuracy of load simulation, even an increase in the running time during the simulation of agricultural equipment loads. This study aims to clarify the effect of state number on the simulation when the MCMC was applied to agricultural equipment load. Specifically, the mean error, standard deviation error, and deviation of rain flow matrix between the simulated and original load decreased rapidly to stabilize, as the state number increased. Moreover, the indicators were not generalizable, if there was no significance between them. An optimization of state number was also proposed using pseudo damage consistency. As such, the damage consistency between the simulated and original load gradually improved and smoothed out, as the state number increased, whereas, the rate of increase in the operation time continued to increase. The optimal state number was calculated to satisfy the damage consistency and minimum operation time, where a threshold value was set for the pseudo damage factor. Furthermore, the field tests were carried out for both tractor ploughing and soil preparation. The specific parameters were measured to validate, including the front axle vibration, front axle stress, and driveshaft torque load. The vibration loads were also utilized to apply for the tractor front drive axle during ploughing operations. It was found that the MCMC using optimal state number can be expected torealize the load simulation with pseudo damage differences within 1%. Furthermore, there were more significant differences between the load segments in the adjustment stage, where the optimal state numbers for each load segment were more dispersed than that in the operation stage. A cyclic simulation was also developed for the loads of key components, according to the operational characteristics of a tractor. Subsequently, the MCMC cycle simulations were also performed on the front axle vibration loads for ploughing. The results show that the simulated load retained the alternating switching between the operating and adjustment stages under tractor ploughing. The same procedure was used to simulate the stress load on the front axle under ploughing, where the torque was separately loaded on the driveshaft under soil preparation. The statistical characteristic indicators were selected, including the mean, standard deviation, and the maximum load cycle amplitude for each load segment. The deviation range of each statistical eigen value was also obtained, compared with the original. The eigen values simulation for each load segment was in a higher agreement with the original eigen values. The generality was further validated when applied to the load simulation of agricultural equipment with the objective of load spectrum preparation. Consequently, the MCMC using optimal state number was better matched to the target requirements of load spectrum preparation, compared with the conventional. The finding can also effectively reduce the computational cost for the higher accuracy during load simulation of agricultural machinery.
    2021,37(20):23-33, DOI: 10.11975/j.issn.1002-6819.2021.20.003
    Abstract:
    Abstract: A batch seed cleaner is a piece of special equipment to meet the specific processing of plot breeding materials. A rubber ball sieve-cleaning device can usually be used as an accessory for a seed cleaner to keep sieve cleaning and avoid sieve-mesh blocking. The sieve-cleaning performance of rubber ball sieve-cleaning devices has an important influence on the operation efficiency and quality of batch seed cleaners. The impulsive force of the rubber ball on the sieve is the key factor to determining the cleaning performance. In this study, the structural and working principles of rubber ball sieve-cleaning devices were introduced to theoretically analyze the random elastic collision screening of rubber balls for the accurate acquisition of impulsive force. An EDEM-MBD coupling model was built for a batch seed cleaner using Hertz-Mindlin in contact mode. A piece of sieve-developed test equipment was utilized to measure the contact parameters, such as the restitution coefficient and friction coefficient for the contact model. A rubber ball impulsive force measurement device was built to obtain the real force of a single ball, according to strain-force measurement. The average and the maximum impulsive force of a single rubber ball were effectively obtained, with the acceptable relative errors between the simulation and measured value, less than 5 % and 10%, respectively. The Box-Behnken experiments with four-factor and three-level were conducted to simulate the impulsive force of sieve-cleaning devices under different working conditions. The mathematical relationships were established between the average or the maximum impulsive force and parameters, such as the amplitude, vibration frequency, screening inclination angle, and ball number. The impulsive force of the rubber ball sieve-cleaning device under different parameters was easily obtained using regression equations. The maize seeds cleaning test under different vibration frequencies was carried out with the index of blockage number, where the relationship was between the blockage number of sieve and impulsive force of the sieve-cleaning device. The test results show that the sieve-cleaning device presented an excellent performance with no blockage on the sieve, with an average impulsive force of 8.87 N and the maximum impulsive force of 18.78 N, when the vibration frequency was 7.2 Hz. An optimal combination was achieved for the screening performance if the average impulsive force not less than 9 N or the maximum impulsive force not less than 19 N. The finding can provide a strong design reference for the screening mechanism and parameter optimization of rubber ball sieve-cleaning devices.
    2021,37(20):34-43, DOI: 10.11975/j.issn.1002-6819.2021.20.004
    Abstract:
    Abstract: A spoon-type potato seed-metering has been widely used for easy preparation and seeding feasibility, due to its simple structure and low price, especially for small and medium-sized planters. But the relatively low reliability of seed-metering has led to the huge loss and significant reduction of yield, where the common miss-seeding rate can be about 5%-7%.Thetraditionalphotoelectric monitoring system cannot fully meet the high performance of anti-dust and anti-vibration. In this study, a new approach was proposed to construct a space capacitance sensor for the evaluation of seed-metering states and mass acquisition of seed potatoes. Specifically, the capacitance variation was obtained in the process of working seed spoon, when passing through the space surrounding the capacitor plates. A theoretical derivation was carried out first to evaluate the feasibility of the potato seed-metering state, according to the maximum net capacitance fluctuation (MNCF) signal. Furthermore, a Maxwell model was performed on the spatial capacitance sensor to determine the range of capacitance using the parameters and morphology of key components in a typical potato seeder. There was a direct influence of all parameters on the size of space capacitor plates to be constructed, including the shape of seed spoon, spoon chain, and the diameter of cutting seed tuber. Since the larger capacitance plates allowed for the higher base capacitance, there was no obvious fluctuation in the maximum net capacitance, when the seed tuber passed through the surrounding space. As such, the sensor sensitivity was reduced significantly. However, the misjudgment inevitably occurred, due to the insufficient sampling data, where the sampling frequency of the system was not enough, if the capacitor plate was too small, while the potato seed on the spoon moved quickly, particularly when the system working at a higher speed. Taking MAX038 as the core, the capacitance of the space capacitance sensor was indirectly obtained by c/f conversion-frequency measurement, and then the MNCF related parameters were calculated, according to Nyquist sampling. A special bench test of seed potato movement was also conducted under the constant temperature and humidity environment, thereby acquiring the regression models of temperature and humidity on the measured parameters. More importantly, the measurement data under different conditions was freely converted to a standard state. The specific parameters of the standard state were the temperature of 15℃ and humidity of 50% RH. In terms of different-sized seed potatoes with the same breed, there was a significant linear relationship between the MNCF and the weight. It was found that the system atic measurement error of spatial capacitance was less than 1%, and the error of seed potato mass acquisition was not more than 3%. The miss-seeding was determined accurately within the test range. Nevertheless, 2.33% of 1-seed normal-seeding was misjudged as the multi-seeding, and 2.78% of the 2-seeds multi-seeding was misidentified as normal-seeding, for the irregularity of test seeds. Misjudgment mainly occurred in an extreme case, particularly whether the single seed potato was too large, or the double seed potato was too small. Overall, the accuracy of the system was still higher than before. Correspondingly, the system performance under actual conditions can be widely expected to perform well on a complete judgment of normal-, miss- and multi-seeding at one time in the scheme. The finding can also provide a new reference for highly reliable monitoring of the potato seed-metering under severe dust and violent vibration environments.
    2021,37(20):44-52, DOI: 10.11975/j.issn.1002-6819.2021.20.005
    Abstract:
    Abstract: To quantitatively study the influence of the impeller outlet circulation distribution on the optimization results of the mixed flow pump, the mixed flow pump with a specific speed of 511 was selected as the baseline model. A comprehensive optimization system was used to optimize under two different conditions, and the performance of the optimization results were compared with the baseline model. In the first case, the influence of the distribution form of the impeller outlet circulation on the optimization result of the mixed flow pump impeller was not considered, that is, the free vortex design (constant distribution of impeller outlet spanwise circulation) was adopted, while in the second case, the effect of circulation distribution was considered, and the forced vortex design (linear distribution of impeller outlet spanwise circulation) was adopted. The optimization system consists of an inverse design method, an optimal latin hypercube sampling method, a radial basis function neural network model and a multi-island genetic algorithm. The optimization objective is the weighted efficiency at 0.8Qdes, 1.0Qdes and 1.2Qdes with weighting factors of 0.2, 0.5, and 0.3 (Qdes means design flow rate). The constraints are the head change of the optimized mixed flow pump at 1.0Qdes less than 3% compared to the baseline model design point, and the pump section efficiency at 0.8Qdes, 1.0Qdes and 1.2Qdes is greater than the baseline model. The research results showed that in the forced vortex design, when the circulation value at the hub was selected as the design parameter, it is feasible to combinedly use the continuity equation, the energy conservation equation and the radial balance equation to calculate the spanwise distribution of impeller outlet circulation. Which can ensure that the pump section head changes of the sampling points under the design condition are within a reasonable range (the range of head variation is less than 10% of the baseline model design head), and there is no need to add new sample points. In addition, the comparison of the predicted head and calculated head of the optimal solution also shows the same result. The results of local sensitivity analysis showed that the impeller outlet spanwise circulation distribution control parameters has a greater impact on the pump section weighted efficiency, and it can influence the other design parameters effect on the weighted efficiency. Therefore, it is necessary to consider the influence of the impeller outlet circulation in the optimal design of the mixed flow pump. The internal flow analysis showed that the forced vortex design can more effectively control the flow regime near the impeller outlet than the free vortex design. This is not only conductive to the improvement of the efficiency of the impeller, but also to the reduction of the hydraulic loss of the downstream components of the impeller, thereby further improving the overall optimization effect of the mixed flow pump. In the free vortex design, the weighted efficiency of the optimization result is 84.14%, while in the forced vortex design, the weighted efficiency of the optimization result is 85.08%, and the heads of both all meet the constraint conditions. This study can provide reference for the optimization design of turbomachinery, so as to maximize the optimization effect.
    2021,37(20):53-62, DOI: 10.11975/j.issn.1002-6819.2021.20.006
    Abstract:
    Abstract: Sowing stubbles with straw in ridges have seriously caused the entanglement, blockage, and resistance to the subsoiler and subsequent machine tool when returning corn straws to the field in the northeast areas of China. The purpose of this study was to establish a discrete element model of subsoiler-soil-straw-stubble for the motion behavior of straw during subsoiling operation, thereby exploring the movement and mechanical characteristics of straw under different conditions. The soil bin was also built as a common ridge in Northeast China. Among them, the straw was assumed as a rigid body, whereas, the breakable adhesive stubble was an unbreakable rigid body. The simulation and test data were then selected to investigate the motion mechanism of straws. Specifically, the tracking movement of straw was obtained as the simulation data. A high-speed camera was also utilized to record the movement data of straw in the field test. As such, the large variation in the movement of straw was better simulated during subsoiling operation, particularly in the complex field environment. Four influencing factors were achieved to represent the straw plucking away from the ridge in the operation of subsoiling, including the distance between the straw and the center of the ridge, the angle between straw and machine, the state of stubble (cutting in the middle of stubble, cutting on one side of stubble, picking up of stubble and no stubble), and the interaction between straws. Correspondingly, the displacement and torque of straws on ridges were obtained to determine the disturbance-specific resistance (the ratio of straw disturbance moment to subsoiler resistance) under the action of the subsoiler. The simulation results show that the distance between the straw and the center of the ridge presented the greatest influence on the horizontal and lateral movement of straws, where the horizontal-lateral displacement of straw decreased with the increase of the angle between the straw and machine. More importantly, there was the largest displacement in the forward direction of straw, when the angle of straw was 45°. The primary and secondary order of stubble state affecting straw displacement was as follows: stubble pick up > stubble side cutting > no stubble > stubble middle cutting. Especially, there was the greatest influence of the interaction between the straws on the forward direction of straws, when the distance between the straw and the center of the ridge was 60 mm. Once more than 60 mm, the displacement tended to increase in the forward direction of straws. In addition, the torque of straws was calculated to explore the rotation of straw in simulation tests. It was found that the overall trend was as follows: the peak value was generated after the stable operation, and then tended to be stable. Anyway, there was a great influence of stubble on the torque of straw. The errors of the total displacement, horizontal-lateral displacement and forward displacement obtained by the simulation model with the test values were 0.36% -9.67%, 0.16% -12.31%, and 0.56% -10.11%, respectively. The error of straw torque was also 0.16% to 11.06%. The error between the test and simulation value was within the allowable range, indicating a similar changing trend. Consequently, the test verified the rationality and feasibility of discrete element simulation. The finding can greatly contribute to understanding the mechanism of straw during subsoiling, particularly to the reasonable design of subsoil machinery in modern agriculture.
    2021,37(20):63-70, DOI: 10.11975/j.issn.1002-6819.2021.20.007
    Abstract:
    Abstract: A multi-layer fertilization has been considered as an efficient way to meet the needs of fertilizers at different growth stages of crops. A layered fertilization device is usually used for the process of ditching and covering soil after ploughing. In this case, the movement of soil particles is very complicated. In this study, an EDEM discrete element software was used to simulate the process of soil accumulation and sliding in the layered fertilization area, in order to calibrate soil contact parameters. A Hertz-Mindlin non-slip model was selected to simulate the contact surface of soil-soil and soil-layered fertilization device (65 Mn steel), according to the soil characteristics of cotton fields after ploughing. Three common shapes of soil particles were represented by Dual Surface, Square Four, and Straight Four. The calibration parameters were also selected to determine the ranges. Specifically, the static friction coefficient, rolling friction coefficient, and collision recovery coefficient between soil-soil and soil-65 Mn steel were used as test factors, while the soil angle of repose, and sliding friction angle of soil-Mn steel were used as evaluation indicators. The universal rotation center combination test was conducted to verify the model. The Design-Expert software was then utilized to perform the regression on the test data. The results showed that the coefficient of recovery from the collision of soil-soil and soil-65 Mn steel presented no significant effect on the angle of repose and sliding friction of soil. Taking the measured soil angle of repose and the sliding friction angle between the soil and 65 Mn steel as the optimization objectives, an optimal combination of discrete element contact parameters was obtained: the coefficient of restoration between soils was 0.48, the coefficient of rolling friction between soils was 0.56, the coefficient of static friction between soils was 0.24, the coefficient of restitution between the soil and 65 Mn steel was 0.5, the coefficient of rolling friction between soil and 65 Mn steel was 0.1, and the coefficient of static friction between soil and 65 Mn steel was 0.31. A soil accumulation test and the sliding test were also compared with the actual test, in order to verify the accuracy of the optimized parameters. The relative errors of the two tests were 1.7% and 2.5%, respectively, under the optimal combination of calibration parameters. Consequently, the discrete elements can be expected to simulate the ditching and soil covering process of the layered fertilization device. The relative errors of simulation and field test were 10.2%, and 7.95%, respectively, at the operating speed of 5, 6,, and 7 km/h of layered fertilization device. Among them, the error of 7.04% was within the acceptable range. Consequently, the simulation and field test presented basically the same effect of ditching and covering soil, indicating the high accuracy and reliability for the calibration of soil contact parameters. The finding can provide strong theoretical and technical support for the later research on drag reduction of layered fertilization devices.
    2021,37(20):71-80, DOI: 10.11975/j.issn.1002-6819.2021.20.008
    Abstract:
    Abstract: Accurate and rapid acquisition of growth information has been one of the most important steps for winter wheat production in agricultural development and management decision-making. Most previous achievements focus on the monitoring of crop growth using Unmanned Aerial Vehicle (UAV) in recent years. Among them, the most extensive reports can be chlorophyll, biomass, plant height, and water content. Taking the winter wheat as the research object, this study aims to monitor the growth characteristics of the plant under a UAV using the Coefficient of Variation (CV) and optimized neural network. A Comprehensive Growth Monitoring Indicators (CGMICV) was also considered to integrate with the CV and different indexes, including the biomass, plant height, plant water, and chlorophyll content. In addition, the multispectral data of UAV was obtained, such as red, green, red edge, and near-infrared band. Subsequently, 16 multispectral vegetation indices were selected to analyze the correlation between the vegetation index and CGMICV, according to the characteristic band range of crops. The variance expansion factor was then calculated to screen the input variables of the model. Finally, six optimal vegetation indices were selected as the input variables of the model. As such, the growth model of winter wheat was established using the Partial Least Squares Regression (PLSR), Random Forest (RF), and Back Propagation Neural Networks (BPNN). Correspondingly, an optimal growth inversion model of winter wheat was achieved, including the determining coefficient (R2), Root Mean Square Error (RMSE), and Mean Absolute Error (MAE), according to the combined evaluation indexes. More importantly, Genetic Algorithm (GA) was utilized to optimize the growth inversion model for the whole region. The spatial distribution of winter wheat growth was then obtained in the study area. The results showed that the correlation between the CGMICV of winter wheat was much higher than that of the single index, where the most outstanding one was the Soil Plant Analysis Development (SPAD). The best inversion model of CGMICV-BPNN was achieved for the growth of winter wheat, where a determination coefficient R2 was 0.71, and the accuracy of the model was 26.79% higher than that of the traditional one, fully meeting the current accuracy for the comprehensive monitoring of crop growth. The stability of the optimized CGMICV-GA-BPNN model was significantly better than that of CGMICV -BPNN. the mean relative error median was reduced by 22.22%, and the determination coefficient R2 was also increased. The CGMICV-GA-BPNN model was then applied for the growth distribution map of winter wheat in the whole study area. More than half of winter wheat was concentrated in grade III, followed by grade I, followed by grade I. It inferred that the overall growth of winter wheat was relatively stable. At the same time, it was also found that the optimized CGMICV -BPNN model can be used to integrate the multiple growth factors of winter wheat, indicating a better performance to quantify the growth monitoring of regional winter wheat. The findings can provide an important reference for the growth monitoring of winter wheat in crop production.
    2021,37(20):81-89, DOI: 10.11975/j.issn.1002-6819.2021.20.009
    Abstract:
    Abstract: A seedling quantity is a key indicator to predict the actual production, supply, and demand for the operation and management of a nursery. The manual visualization has still dominated the statistics for the number of seedlings in complete plots. However, the application needs cannot be fully met in recent years, such as high cost, low efficiency, and slow data update. Therefore, it is necessary to fast and accurately estimate the number of seedlings in the whole plots. Taking the spruce as the research object, this study aims to propose a quantity statistics approach under Unmanned Aerial Vehicle (UAV) aerial videos using YOLOv3 and SORT. The specific procedure included the data acquisition, YOLOv3 detection model, SORT tracking, and cross-line counting. Two areas were divided for the image and video acquisition, each with 6 complete test plots. In the stage of data acquisition, 558 images and 6 videos were captured by a DJI Phantom 4 (UAV). The quantity statistics dataset was then constructed with the acquired images and videos, where the training dataset contained 558 images, and the test dataset contained 6 videos. Subsequently, a YOLOv3 model was selected to detect the spruce, while a SORT model was to track the spruce, and the cross-line counting to count the number of spruce. The performance of the combined YOLOv3+SORT was also quantitatively evaluated using Mean Count Accuracy (MCA), Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and Frame Rate (FR). It was found that the MCA of 92.30%, MAE of 72, RMSE of 98.85, and FR of 11.5 frames/s for the test dataset in the quantity statistics. The experimental results showed that quick and accurate counting was achieved for the number of spruce in the complete plots. The YOLOv3+SORT was also compared with the SSD+SORT and Faster R-CNN+SORT, in order to further verify the performance of the model. The results show that the YOLOv3+SORT performed over the SSD+SORT in all four evaluation indexes. Particularly, the YOLOv3+SORT was much faster with higher guaranteed accuracy, with 1.33% lower MCA, and 10.1 frames/s higher FR, compared with the Faster R-CNN+SORT. In summary, the quantity statistics using YOLOv3 and SORT can be widely expected to serve as an effective way to rapidly and accurately count the number of seedlings in the whole plots. This study can also offer promising potential support to the seedling quantity statistics from the perspective of UAV aerial videos.
    2021,37(20):90-98, DOI: 10.11975/j.issn.1002-6819.2021.20.010
    Abstract:
    Abstract: A sugar beet is one of the most important cash crops in northern China. It is a high demand for the rapid, accurate, and high-throughput acquisition of the fresh weight of aboveground and root, the sugar content of root, and the chlorophyll content of aboveground in the production of sugar beet. An Unmanned Aerial Vehicle (UAV) can serve as a significant approach, due to its flexibility, low cost, and high spatiotemporal resolution. In this study, a UAV equipped with digital and multispectral cameras was utilized to capture the images of sugar beet during the leaf clusters, root tuber, sugar growth, and accumulation period, thereby extracting the structural and spectral characteristics of the canopy. The estimation models were also established for the various indexes using the Random Forest Regression (RFR) and Partial Least Squares Regression (PLSR), including the fresh weight of shoot and root tuber, the sugar content of root tuber, and Soil Plant Analysis Development (SPAD) value during the whole period of sugar beet. The results showed that the RFR and PLSR model performed well to predict the fresh weight and sugar content of shoot and root tuber, with the coefficient of determination R2 ranging from 0.9 to 0.94 and from 0.88 to 0.9, respectively, while the relative Root Mean Square Error (rRMSE) ranging from 7.6% to 17% and from 8.8% to 20%, respectively. Both models presented weak predictions for the SPAD values, where the R2 values were only 0.66 and 0.67, respectively. Furthermore, a Permutation Importance (PIMP) was used to screen the more sensitive variables with the dominated impacts on the prediction, in order to reduce the size of the input variable set for the less cost and complexity of data collection. As such, the optimal prediction models of RFR and PLSR were achieved for the growth monitoring of sugar roots. It was found that excellent predictions were achieved on the fresh weight and sugar content of shoot and root tuber, with the R2 value ranging from 0.89 to 0.94, and from 0.74 to 0.91, respectively, and the rRMSE value ranging from 7.3% to 19% and from 7.6% to 19%, respectively. Nevertheless, the RFR and PLSR model presented weak predictions for the SPAD values, where the R2 values were only 0.65 and 0.68, respectively. Correspondingly, the accuracy of the RFR model was slightly better than that of the PLSR model. More importantly, the PIMP variable screening can be widely expected to reduce the complexity of data collection with optimal accuracy. Consequently, the canopy structure and spectral features obtained by UAVs can be utilized to quickly and accurately monitor the growth and sugar content of sugar beet. The finding can provide a strong reference to estimate the root active substances of tubers crops using UAV proximity.
    2021,37(20):99-107, DOI: 10.11975/j.issn.1002-6819.2021.20.011
    Abstract:
    Abstract: About 215 billion cubic metres of water has been consumed by large and medium-sized irrigation districts in recent years, particularly over 35% quantity of the total water consumption in China. The irrigation district has been the main field of agricultural water-saving construction. Therefore, it is necessary to accurately assess the water-saving level in modern irrigation districts. In this study, an index system was established to evaluate the water-saving level in large-scale irrigation districts. Five aspects were considered, including engineering water-saving, farmland water-saving, water use management, water resources protection, and water use benefit. Eight standards were selected, such as measurability, vulnerability, predictability, typicality, controllability, integrity, responsiveness, and stability. A screening model was constructed to identify the indexes to be shortlisted or not. Subsequently, 23 indexes from the 70 primary indexes, 86.42% of the information was expressed by 32.86% of the elementary indexes, indicating the concise and adequate index system. The final indexes were formed, including the backbone canal lining ratio, the completion rate of engineering projects, backbone canal intact rate, backbone hydraulic structures intact percentage, water utilization coefficient of canal system, high-efficient water-saving irrigation coverage percentage, field water utilization coefficient, multi-cropping index, gross irrigation water consumption per mu, real collection rate of water charges, water user association coverage rate, allocation rate of water measuring equipment on lateral gate, 2 fees implementation rate, number of management personnel per 10 000 mu, proportion of management personnel with junior college degree or above, informationization coverage rate, proportion of irrigation water in total water consumption, drainage ditch intact rate, water ecological monitoring system coverage rate, proportion of ecological water in the total water consumption, grain yield produced by 1m3 irrigation water, proportion of primary industry production in irrigation district, and water consumption per-10 000-yuan-GDP. Four large-scale irrigation districts (Qucun, Penglou, Guangli, and Dagong) are all located along the Yellow River in Henan Province. The indexe system was then investigated empirically to determine the water-saving level. The water-saving level indexes for the four objective Irrigation Districts were 0.666 (Qucun), 0.730 (Penglou), 0.657 (Guangli), and 0.616 (Dagong), respectively. On the whole, the score of the water-saving level index was ranked in the descending order of Penglou, Qucun, Guangli, and Dagong. The scores of the 5 secondary indexes showed that Penglou achieved the best effect of engineering water-saving, whereas, Dagong was a negative example. This was due to the well-matched infrastructure engineering, where the backbone canal system was of systematic construction and renovation in the past 10 years. Guangli performed relatively lower than the rest because the high-efficient coverage percentage of water-saving irrigation was rather weak and the gross consumption of irrigation water per mu was pretty high, particularly for the long-term goals of farmland water-saving. There was no significant difference in the score of water use management level among the four irrigation districts, but their agriculture water rate, water user association promotion, and water measuring facilities setting, all needed to be rather improved. Water resources protection was the common weakness of the four irrigation districts, indicating the concept of project construction without considering ecological protection over the past years. Consequently, five recommendations can be addressed to further improve the water-saving level in the irrigation districts. 1) To coordinate the backbone and field construction, 2) To establish the new water-saving system under the agricultural water price reform, 3) To strengthen the dredging and transformation of drainage ditches, 4) To improve the water resources and environment monitoring network, 5) To promote the efficient saving on water irrigation, particularly for the planting area of cash crops. The findings can provide an effective way to scientifically evaluate the water-saving construction in large-scale irrigation districts, thereby promoting the process of agricultural water-saving in China.
    2021,37(20):108-116, DOI: 10.11975/j.issn.1002-6819.2021.20.012
    Abstract:
    Abstract: Water is a determining factor in crop production, particularly with the increase of irrigation areas and crops in recent years. Water shortage has posed a great challenge to crop production in North China. Fortunately, the nitrogen (N) fertilizer can serve as another key factor for crop growth and yield formation. However, there is a severe unbalance between the supply of N fertilizer and crop demand. It is also a trade-off between the irrigation and N fertilizer in most parts of Agro-Pastoral Ecotone (APE), which is one of the staple production regions for potatoes in China. Therefore, it is necessary to optimize the irrigation and N management for potato sustainable production using various production goals under different precipitation years. In this study, 27 study sites in the APE were selected to explore the coupling impacts of irrigation and N on the potato yield, Water Use Efficiency (WUE), and economic benefits using the Agricultural Production Systems Simulator (APSIM) Potato model. A two-year field experiment was also carried out under different treatments of irrigation and N fertilizer at a typical site in the APE. Specifically, ten irrigation levels were set in the test, where the deficit values ranged from 10 to 100 mm with the interval of 10 mm, while the application amount of N fertilizer ranged from 30 to 210 kg/hm2 with the interval of 30 kg/hm2. Three types of precipitation years (dry, normal, and wet) were divided in the APE, according to the guarantee rate of precipitation. Subsequently, the WUE was calculated using the ratio of fresh potato yield to evapotranspiration. The economic benefit was the difference between the gross income and the total inputs, where the gross income was the product of the total fresh yield and unit price. Among them, the inputs included the cost of seeding, irrigation, fertilization, use of fungicides and pesticides, tillage, planting and harvesting, and labor. The results showed that the APSIM-Potato model performed well to simulate the phenology, the soil water content of 1m depth, potato N uptake, and yield. The yield of rainfed potato without the application of N fertilizer was ranged from 4 760 to 18 500 kg/hm2, from 9 200 to 20 900 kg/hm2, and from 11 900 to 21 500 kg/hm2 under dry, normal and wet precipitation years, respectively. More importantly, the yields were the lowest in the middle APE under all types of precipitation years. The maximum yield of potato was achieved under the dry year using different combinations of irrigation and N fertilizer. In addition, an optimal combination was achieved to maximize the yield, where the irrigation inputs were 589, 544, and 512 mm in dry, normal, and wet years, respectively, while the N application amounts were all 210 kg/hm2. The irrigation inputs were much higher in the eastern and western APE under all precipitation year types. The maximum WUEs were 85.9, 90.2, and 92.2 kg/ (mm·hm2) in the dry, normal, and wet years, respectively. An optimal combination was also achieved to maximize the WUE, where the irrigation inputs were 172, 107, and 87 mm in the dry, normal, and wet years, respectively, while the amounts of N were 60-120 kg/hm2. Among them, the proportion of sites with 60 kg/hm2 was the highest in the dry years. As such, the maximum economic benefits were 19 340, 18 610, and 18 470 Yuan/hm2 in dry, normal, and wet years, respectively. An optimal combination was also achieved to maximize the income, where the irrigation inputs were 226, 152, and 116 mm in dry, normal, and wet years, respectively, while the application amounts of N were 30-90 kg/hm2 in different year types. The proportion of sites with 90 kg/hm2 was the highest in the wet years. The finding can greatly contribute to formulating optimal management of irrigation and N fertilizer, according to various goals of potato production under different precipitation years.
    2021,37(20):117-126, DOI: 10.11975/j.issn.1002-6819.2021.20.013
    Abstract:
    Abstract: Drought and less rainfall is one of the main factors affecting the high quality, high yield and stability of apples on the Loess Plateau. In apple orchard, ridging and film mulching in the tree tray with rows clearing (F) is currently the most commonly used orchard mulching modes to preserve soil moisture, but moisture preservation is limited and still needs to be improved. For this reason, in the 17-year-old apple orchard in the main apple-producing area of the Loess Plateau in east Gansu province, on the basis of perfecting the ridge mulching of tree trays (F), it is combined with the straw mulching between rows to form a whole garden mulching model (F+W ), and on the basis of F+W, water seepage holes were added on the sides of film in row to form a three-dimensional moisture preservation model (F+W+H), with no ridging and no coverage as the control (CK). Continued three years a fixed point test was carried out to study the effects of different mulching models on soil moisture contents before flowering, in fruit expansion stage and after harvest, as well as nutrient effects and tree growth response. The results showed that the average moisture content of 0-100 cm soil layer in the three phases of the three mulching patterns was higher than that of CK in 2015(drought year),which of 0-100 cm soil layer of in 2016 (Autumn drought year), and 0-100 cm and 100-200 cm soil layer in 2017 (normal rainfall) of both F+W+H and F+W were extremely significant (P<0.01) while F significant (P<0.05) higher than CK. After harvest inter-annual the average moisture contents of 400-500 cm soil layer of F+W+H and 300-500 cm soil layer of F+W did not decrease significantly, but F and CK decreased significantly. From before flowering in 2015 to after harvest in 2017,the order of the total evapotranspiration of 0-500 cm soil layer for three years was F+W+H
    2021,37(20):127-135, DOI: 10.11975/j.issn.1002-6819.2021.20.014
    Abstract:
    Abstract: This study aims to explore the effect of magnetization treatment on the clogging of drippers for the integrated drip irrigation of water and fertilizer in the area of the Yellow River. Taking the inner-embedded drip emitter as the research object, the intensity of magnetization was set to 0.2, 0.4, and 0.6 T, where the control group was unmagnetized. A short-term intermittent irrigation test was also carried out for 2% of the mass of potassium sulfate fertilizer, urea, and compound fertilizer muddy water (sediment content of 3.0 g/L). The results showed that the magnetization significantly slowed down the downward trend of dripper flow and irrigation uniformity (P<0.01). The optimal magnetization intensity greatly varied in the different fertilizers. Specifically, there was the greatest mitigation effect of dripper flow for the mixture of potassium sulfate fertilizer and compound fertilizer, when the magnetization intensity was 0.4T. The greatest mitigation effect was found during the decrease in the flow rate of the dripper in the urea mixture at the magnetization intensity of 0.2 T. The effective irrigation times for the mixture of potassium sulfate fertilizer, urea, and compound fertilizer without magnetization treatment (irrigation times with a relative flow rate greater than 75%) were 10, 10, and 3 times, respectively. Furthermore, the effective irrigation times of different fertilizer mixtures increased after the magnetization treatment. When the magnetization intensity was 0.4, 0.2, and 0.4 T, the effective irrigation times of potassium sulfate fertilizer, urea, and compound fertilizer mixture increased the most, which were 16, 15, and 7 times, respectively. The number of clogged emitters increased significantly in the front section of the capillary tube for the potassium sulfate fertilizer and compound fertilizer treatment, whereas, the urea decreased after magnetizing the irrigation water. In the 0.4 T treatment, the most increased number of blocked drippers was found in the front section of the capillary for the potassium sulfate fertilizer and compound fertilizer mixture, which were 30.56% and 12.94%, respectively. In the 0.2 T treatment, there was the largest decrease (44.29%) in the number of blocked drippers in the front section of the urea mixed liquid capillary tube. The ratio for the amount of sediment in the capillary tube to the amount of sediment output from the dripper was represented by η under different magnetization treatments. When applying potassium sulfate fertilizer and compound fertilizer, the magnetization treatment increased the value of η, indicating the largest increase at 0.4 T. By contrast, the magnetization treatment reduced the value of η, when the urea was applied, indicating the most obvious decrease at 0.2 T. As such, the magnetization significantly dominated the sedimentation and movement for the sensitive particle size of emitter blockages. Specifically, the magnetization significantly increased the proportion of sensitive particle size (smaller than 0.03 mm) in the siltation sediment for the capillary of the potassium sulfate and the compound fertilizer mixture, reducing the proportion of sensitive particle size in the sediment output from the emitter, where that of urea was the opposite. When the magnetization intensity was 0.4 T, after applying potassium sulfate fertilizer and compound fertilizer, the sediment-sensitive particle size in the front and middle of the capillary increased the most: 11.23%, 6.37%, and 6.10%, 4.91%, respectively. After applying urea, the magnetization presented the largest decrease, when the magnetization was 0.2 T. When the magnetization intensity was 0.4 T, the proportion of sensitive particle size in the output sediment of the potassium sulfate and the compound fertilizer mixture dripper presented the largest decrease, which was 5.33% and 4.61%, respectively. When the magnetization intensity was 0.2 T, the urea mixed liquid dripper presented the largest increase in the proportion of sensitive particle size in the sediment output, which was 5.26%. The finding can provide a strong reference for the anti-clogging prevention measures in the drip irrigation drippers with integrated water and fertilizer in the Yellow River irrigation areas.
    2021,37(20):136-145, DOI: 10.11975/j.issn.1002-6819.2021.20.015
    Abstract:
    Abstract: A slope farmland has been one of the most serious land-use types of soil and water loss, as well as the non-point source pollution. Natural conditions and unreasonable farming have also posed great damage to the ecological environment, particularly on the quality degradation of slope farmland. Therefore, it is very necessary to construct the quality control system of slope farmland in recent years. Taking sloping farmland in Yunnan province of China as a research object, a factor analysis model was first established to diagnose the quality obstacle factors of slope farmland. The types of quality obstacles were then ranked to define in each region, thereby identifying the controllable factors, the regulation priority, and objectives of slope farmland quality. The quality regulation potential of slope farmland was calculated to determine the zoning regulation mode in different regions. The results show that: 1) The main types of quality obstacles were erosion degradation, drought, and water shortage, as well as the nutrient poverty type in the sloping farmland. There was some difference in the combination and performance of obstacle factors in different regions. 2) The adjustable factors of slope farmland quality included the thickness of arable layer, soil bulk density, pH value, organic matter, the total nitrogen, available phosphorus, available potassium, irrigation assurance rate, and field slope, among which the field slope, soil organic matter, irrigation assurance rate, available phosphorus, available potassium and pH value were the priority adjustment and control factors. The goal of quality control in the sloping farmland was to make the controllable factors in the appropriate range under various control measures. An optimal range of factors were achieved, where the thickness of plough layer ≥17.35 cm, soil organic matter ≥28.89 g/kg, soil available phosphorus ≥32.44 mg/kg, soil available potassium ≥137.81 mg/kg, irrigation assurance rate ≥73.33%, soil bulk density ≤1.31 g/cm3, field slope ≤12.87°, and pH value 6.06-8.06. 3) The objectives of quality control in the sloping farmland included the ideal and actual state. In an ideal state, the potential of quality control in the sloping farmland was 0.347, indicating an upgrade from the "medium" to the "high" level. In the actual state, the potential of quality control in the sloping farmland was 0.198, indicating that the quality level was improved from the current "medium" to "high". The potential of actual state control was used as the standard quality control of slope farmland. 4) According to the general idea of "erosion control, water regulation, and fertility enhancement", the integrated mode of quality control in the sloping farmland was constructed as follows. The tillage modes were utilized to promote soil and water conservation, such as ridge, contour, and reverse slope tillage, as well as the conservation tillage (rotary, subsoiling, and no tillage + deep tillage) in farming measures. The water engineering slope to ladder project and high-efficiency water-saving measures can be implemented to actively promote the straw returning, green and organic fertilizer application. The soil testing and formula fertilization among soil fertility measures can be used to increase the content of soil organic matter and nutrients in the slope cultivated land. This finding can provide a scientific guide for the quality cultivation and management of regional slope farmland at a provincial scale.
    2021,37(20):146-153, DOI: 10.11975/j.issn.1002-6819.2021.20.016
    Abstract:
    Abstract: Laterite is a special type of soil in tropical and subtropical humid areas. It is evolved from carbonate rocks to physical, chemical, and biological weathering, as well as laterization with the color of brown-red, maroon and yellowish-brown. Furthermore, laterite is very likely to crack in a dry environment, due to its sensitivity to ambient humidity. The resulting dry shrinkage cracks have posed a great threat to the strength and stability of the soil. Therefore, there is a commonly-hidden danger of collapse from the shrinkage cracking of laterite in slope projects. Most cracking of cohesive soil comes from the evaporation of water in the soil. Boundary constraints and uneven shrinkage can result in the formation and development of a stress-strain field in the soil. Once the tensile exceeds the maximum tensile strength of the soil, the cracks gradually occur and continue to develop during evolution. In this study, a quantitative analysis was performed on the dry shrinkage cracking of red clay in high liquid-limit laterite in Shaoyang area of Hunan Province in China. A drying test was also conducted to explore the evolution and formation mechanism of cracks in the laterite using slurry samples under natural hot-humid conditions. A three-dimensional strain measurement system was adopted to collect the moisture, displacement, strain, and crack of the soil. Then, a quantitative description was made on the evolution characteristics of crack morphology and strain field during dehumidification, thereby investigating the influence of water content on fracture morphology and strain field. The results show that: 1) Six stages were found in the evolution of dry shrinkage cracks on the surface of the soil sample. The cracks were formed in the later stages with the cracking surroundings from the previous stages. Specifically, the intersection angle of fractures was close to 90o in different stages. 2) Most soil was in the tensile state with a nearly 0.5% strain at the crack tip during the initial stage of crack development. The soil around the cracks gradually evolved into a compressive state, as the crack developed. Once all the cracks developed, the soil around the crack was totally in a compressive state. 3) The evolution of cracks was closely related to the limited water content. Specifically, the cracks on the soil surface began to rapidly develop, widen and extend, when the soil water content approached the liquid limit of 67.7%. The developing rate of crack began to slow down when the soil water content reached the plastic limit of 28.3%. Once the soil water content was less than the plastic limit of 18.8%, there was no obvious change of fracture, indicating that the fracture development was nearly completed. 4) The cracking time and width of early fracture exceeded those of later fracture in the process of fracture evolution. The displacement and strain varied at the different parts of the soil surface. The vertical shrinkage at the center of the soil block was greater than that at the edge, but the displacement and strain at the center of the soil block were much less than that at the edge. The finding can offer a great engineering reference to prevent geological diseases or environmental disasters in laterite areas.
    2021,37(20):154-161, DOI: 10.11975/j.issn.1002-6819.2021.20.017
    Abstract:
    Abstract: Water is a key factor for plant growth and development. Quantifying water sources is one of the most important steps to effectively manage the irrigation of forests during the fruit peak growth period in hilly areas. However, the research on the water use of different fruit growth peaks is still lacking on Camellia oleifera. In this study, a systematic investigation was conducted to quantify the water source of Camellia oleifera forest during the fruit peak growth period using hydrogen and oxygen isotopes. The precipitation, soil, and Camellia oleifera samples were also collected from April-June (the first fruit growth peak) and July-August (the second fruit growth peak) in 2019 and 2020, where the soil sampling depth was 1 m. The soil layer was divided into three layers: 0-30, >30-60, and >60-100 cm, according to the distribution of root and soil water content. Taking Young Camellia oleifera aged 3 to 5 years as subjects, the isotopic composition of xylem and soil water was compared in the active layer of the root system at the peak of fruit growth. Linear mixed and the Bayesian hybrid (MixSIAR) models were used to quantify the water absorption source of the root system. The results indicate that the Local Meteoric Water Line (LMWL) was δD=8.29δ18O+12.99, R2=0.99 during the test period, where the soil and plant water isotope were concentrated near the LMWL. Most isotopes of xylem water were distributed in the range of soil water isotope values, where the soil water was the direct water source. The isotope value of xylem water basically intersected with that of soil water of 0-100 cm. The intersection depth mainly intersected 0-30 cm during the growth peak of the first fruit, and then increased gradually during the growth peak of the second fruit. It inferred that the water source in the first peak period came from the 0-30 cm soil layer, whereas, the water in the deeper soil layer was used in the second peak period. The model results showed that Camellia oleifera presented similar water utilization strategies in the two fruit growth peaks in 2019 and 2020. Specifically, the soil water in the 0-30 cm soil layer was mainly used at the peak of fruit growth. The contribution rates of 0-30, >30-60 and >60-100 cm soil layers were 51.3%, 28.2% and 20.5%, respectively. The water absorption depth increased in the second fruit growth peak, compared with the first growth peak. For example, the results of MixSIAR model showed that the utilization rate of 0-30 cm soil layer decreased by 19%, while the utilization rate of >30-60 and >60-100 cm two soil layers increased by 12% and 8%, respectively. The contributions of three soil layers (unit volume) to water absorption of root were 149.6, 81.1, and 58.7 mm, respectively. There was only a slight difference to simulate the contribution proportion of soil water in each soil layer using linear mixing and the MixSIAR model. This finding can provide a sound reference to formulate a suitable irrigation system for young Camellia oleifera in the southern hilly region. Correspondingly, the forest water and fertilizer construction can also be integrated for the healthy development of Camellia oleifera.
    2021,37(20):162-168, DOI: 10.11975/j.issn.1002-6819.2021.20.018
    Abstract:
    Abstract: This study aims to evaluate the filtration performance of sand filters using fractal dimensions. Three kinds of sand filters were also selected with particle size in the range of 1.0-1.18, >1.181.4, and >1.41.7 mm. The Yellow River sediment in the people's Victory Canal was collected as impurity particles in the raw water. The distribution of particle size in the Yellow River sediment was measured using a laser diffraction particle size analyzer (Mastersizer 3000, Dandong Baite Instrument Co., Ltd). It was found that the calculated mean values of skewness and kurtosis were 0.12 and -0.01, respectively, for the samples from the Yellow River sediment, indicating an outstanding normal distribution. Additionally, the samples were also collected from the Yellow River sediment in Lankao County, thereby verifying the distribution of particle size. It was found that the skewness and kurtosis values of the sediment sample in Lankao County were -0.11 and -0.23, respectively, where the frequency distribution of particle size also conformed to the normal distribution. An industrial CT scanner (C16m3201, Luoyang Tengda Testing Service Co., Ltd) was used to map the filter layer. The image processing and pixel coverage were utilized to calculate the porosity of cross section, the box-counting fractal dimension, and the ratio of the minimum to the maximum aperture (aperture ratio) in the three kinds of sand filter layers. The results showed that the porosities were 0.421, 0.431, and 0.439, respectively, while the box-counting fractal dimensions were 1.695, 1.709 and 1.726, respectively, and the aperture ratio was 1/17, 1/18, and 1/21, respectively, for the three types of layers. Then, the applicability of fractal theory was also evaluated for the quartz sand filters. Subsequently, a fractal model of filtration probability was established for the sand filters. The ranges of pore diameter in the three kinds of sand filters were 59.5-1 002, 66.9-1 220, and 72.9-1 503 μm, respectively. In the sediment of the Yellow River from the people's Victory Canal, the probabilities of impurity particles above 100 um passing through the sand filter were 0.67%, 0.81%, and 0.93%, respectively. In the Yellow River Sediment from Lankao County, the probabilities of impurity particles above 100 μm passing through the sand filter were 0.62%, 0.80%, and 0.91%, respectively. It inferred that the presence of surface filtration was proved theoretically. A systematic investigation was also made on the influence of surface filtration on Backwash frequency. Consequently, an optimal filter layer was achieved to reduce the surface filtration, particularly with the particle size in the range of 1.4-1.7 mm suitable for sand filters. The finding can provide strong support to explore the internal structure of sand filters and the selection of filter material.
    2021,37(20):169-178, DOI: 10.11975/j.issn.1002-6819.2021.20.019
    Abstract:
    Abstract: High-throughput phenotyping has posed an urgent challenge on plant genetics, physiology, and breeding at present. Particularly, traditional manual cannot meet the needs of high-throughput phenotyping for breeding, due mainly to time-consuming and labour-intensive work with a limited sample size. Alternatively, the Unmanned Aerial Vehicle (UAV) Remote Sensing can be widely expected to serve as an important tool for crop phenotypic parameters. The main reason can be the high temporal and spatial resolution, fast image acquisition, easy operation and portability, as well as relatively low cost. However, it is also inevitable to balance the flight height and image resolution or accuracy during image acquisition. Efficient techniques are urgently needed to reconstruct the high-resolution images without lossing the measurement accuracy, while improving the spatial resolution and image acquisition. In this study, the maize phenotypic traits were effectively monitored using super-resolution reconstruction and multimodal data fusion. The UAV image sequences of maize were also captured at seedling, 6th leaf, 12th leaf, tasseling, and milk stage. The super-resolution images were then reconstructed combined with the wavelet transform and bicubic interpolation. The reconstructed images presented higher reconstruction quality, less distortion with peak signal-to-noise ratio of 21.5, structure similarity of 0.81, and mean absolute error ratio of 6.4%. A lower error was also achieved for the plant height and biomass estimation with the root mean square error of 0.39 cm and 0.19 kg, respectively. Ground Sampling Distance (GSD) of the reconstructed image at a flight height of 60 m was similar to that of the original image at a flight height of 30 m. Subsequently, the UAV at a flight height of 60 m was utilized to scan 0.2 hm2 larger fields per minute than that at a flight height of 30 m. The plant height, canopy coverage and vegetation index were also extracted from the original and reconstructed images. Leaf area index was calculated by point cloud reconstructed by oblique photography. The original shape of point cloud was remained, while point cloud was compressed for a higher efficiency using 3-D voxel filtering. Specifically, a better correlation was achieved, where the measured LAI was the slope of 0.72 and the root mean square error of 0.14. All canopy structure, spectrum and population structure parameters were then used to construct estimation models of above ground biomass using single characteristic parameter and multimodal data. A higher estimation accuracy of above ground biomass was obtained by multimodal data fusion, compared with a single parameter with the coefficient of determination was 0.83 and root mean square error of 0.19 kg. Therefore, a combination of image super-resolution reconstruction and multimodal data fusion can be widely expected to deal with the canopy saturation for higher spatial resolution and estimation accuracy, indicating fully meeting the demand for higher throughput of data acquisition. Meanwhile, the finding can provide a highly effective and novel solution to the estimation of above ground biomass. More importantly, the correlation between genotype and phenotype can also be extended to cultivate high-quality maize varieties suitable for mechanized production.
    2021,37(20):179-186, DOI: 10.11975/j.issn.1002-6819.2021.20.020
    Abstract:
    Abstract: A navigation path has been widely considered as one of the most important sub-tasks of intelligent agricultural equipment in field operations. However, there are still some challenges remaining on the recognition of current navigation paths between crop ridges, including the accuracy, real-time performance, generalization, and difficulty in the interpretation of deep learning models. In this research, a new Fast-Unet model was proposed to accurately and rapidly recognize the navigation path between crop ridges using semantic segmentation. The jump connection of the Unet model was also retained to generate the navigation line and yaw angle using the least square regression. Specifically, a cotton dataset of inter-ridge navigation path consisted of 800 images, 640 of which was set as the training set, 160of that as the validation set. Subsequently, two datasets of 100 images each were constructed for the navigation paths of sugarcane and cotton ridges, which were divided into 50 images in the training set, and 50 images in the verification set. The training strategy was selected as the data augmentation and learning rate adjustment. The training order was ranked as the corn first, and then the sugarcane dataset. The Mean Intersection over Union (MIoU) was utilized as the accuracy indicator of the Fast-Unet model, which was 0.781 for cotton, 0.881 for corn, and 0.940 for sugarcane. Furthermore, the least-squares regression was selected to calculate the navigation path of corn and sugarcane with good linearity between the ridges. Additionally, the navigation line was selected to further calculate the yaw angle. The mean difference between the predicted yaw angle of corn and sugarcane navigation path and the labeled were 0.999° and 0.376° under the Fast-Unet model, respectively. In terms of real-time performance, the inference speed of the Fast-Unet model was 6.48 times higher than that of Unet. The inference speed was 64.67 frames per second to process the RGB image data on a single-core CPU, while the number of parameters of the Fast-Unet model was 6.24% of that of Unet model. Correspondingly, the computing devices were deployed with weak computing power, thereby performing real-time calculations. A gradient weighted class activation mapping(Grad-CAM) was also used to visually represent the final feature extraction of model recognition and transfer learning. More importantly, the special features were highlighted on the navigation path between crop ridges in the optimized Fast-Unet structure, concurrently to remove a large number of redundant feature maps, while retaining only the most crucial feature extractors. The transfer learning also presented a larger activation area than the direct training, where the activated area matched the main road to be identified. In summary, the improved model can be fully realized the real-time recognition of crop navigation path. The finding can also provide technical and theoretical support to the development of navigation equipment for intelligent agricultural machinery in the field.
    2021,37(20):187-193, DOI: 10.11975/j.issn.1002-6819.2021.20.021
    Abstract:
    Abstract: Sound has been widely used to monitor the health and body conditions of pigs. But the manual monitoring cannot meet the high demand in modern agriculture at present, including zoonotic diseases, misjudgments of pig diseases, and time- and labor-consuming. In this study, a real-time collection module of pig sound was designed to rapidly recognize the abnormal state using an improved convolutional neural network (CNN). A 4G communication was used to upload the collected pig sound into the cloud server. A TCP/IP communication protocol was also selected, where the acquisition end was set as a TCP client and the uninterrupted data to the server. Specifically, the TCP cloud server was utilized to block the specified port, and then start the transfer data after the client was connected successfully. The server also sent a restart command to the client, to ensure data alignment. The sound acquisition was realized via a single channel, where the sampling frequency was 32 kHz, while the quantization digit was 16 bits. Correspondingly, the raw data of various abnormal sounds of pigs (sickness, fighting, and Hunger) were collected, according to the experts of pig breeding. Some operations were used to preprocess the data, including framing, windowing, de-nosing, and endpoint detection. As such, a voice data set of abnormal status was built. Subsequently, the Mel spectrogram of various sounds was extracted under the parameters of 128-dimensional mel frequency, 2048 points of Fast Fourier Transform (FFT) points, and 512 points of window shift. A classification model of the signal acquisition was then constructed using the feature of Mel spectrogram for pig sound signals. Therefore, a local feature learning unit was designed using an improved CNN, indicating fewer weights and lower network complexity than fully connected networks. Four layers of local feature units were constructed, where the number of convolution kernels in each layer was 64-64-128-128. Nevertheless, the local location and various redundant information were inevitably generated, when CNN had acquired each image. Three types of attention mechanisms were used to improve CNN, including Squeeze and Excitation Network (SE_NET), Efficient Channel Attention Networks, (ECA_NET), and Convolutional Block Attention Module (CBAM). A fully connected network with three neurons and an activation function of Softmax was also used to recognize abnormal sounds of pigs. The CBAM was then optimized to propose the CBAM-CNN using the ECA_NET improved SE_NET. The experimental results show that the optimal combination of parameters in pig voice recognition was 128 dimensional Mel frequency, 2048 point FFT, 1/4 window shift, and the optimal network model was _CBAM-CNN. The optimal recognition accuracy reached 94.46%, and the accuracy of pig squeal recognition reached 100%, better than before. The attention mechanism was also improved the model recognition, while reducing model complexity. A better recognition was achieved using the smaller size of _CBAM-CNN model, compared with CBAM-CNN. The accuracy of _CBAM-CNN model was 94.46% for the sound recognition of abnormal pigs. This finding can provide the accurate monitoring of abnormal behaviors of pigs in the process of breeding, thereby constructing intelligent and modern pig farms.
    2021,37(20):194-201, DOI: 10.11975/j.issn.1002-6819.2021.20.022
    Abstract:
    Abstract: Plug seedlings have been widely used in the production of vegetable and flower planting. The consistent quality of plug seedlings depends mainly on economic benefits. It is usually necessary to identify and remove unqualified seedlings from the plugs, and then replace them with qualified seedlings. The manual operation of substandard seedlings is mainly used from the plugs to the supplement seedling sat present, indicating low efficiency, high labor costs, and unstable classification. The seedling sorting machine using machine vision can automatically identify the lack of seedling holes and unqualified seedlings, and then remove the unqualified seedlings from the plug trays. The accurate classification can be achieved with higher operation efficiency. The top view images are selected to judge the quality of plug seedlings with no crossed leaves and no mutual obscuration. However, the leaves of adjacent seedlings cross each other or are blocked and covered, when most plug seedlings of flower and vegetable are sold. It cannot be evaluated on the growth status and quality of individual seedlings using the top view image. Taking the Spathiphyllum seedlings as the research object, this study aims to observe the local area of seedling stem under the leaves using perspective images under the leaves. An automatic quality inspection of plug seedlings was realized to combine with the judging standard of seedling level, particularly on the stem image covering each other with leaves. Firstly, the critical projection area for the stems of Spathiphyllum seedlings was proposed, according to the production standards. Secondly, an image acquisition unit of the seedling stem was constructed, consisting of a leaf guide piece, a miniature camera, and two light guide fibers. Subsequently, the stem images were captured under the leaf of Spathiphyllum seedlings in the darkroom. Then, the PC vision was utilized to analyze the images and projection area of the seedling stem. The seedlings were determined to be qualified or not, according to the quality evaluation on the projection area and the critical value of the Spathiphyllum seedling stem. The hole positions of unqualified seedlings were returned to PLC at last. A three-factor three-level test was carried out to select the conveyor speed, where the deviation of the center distance between seedling stem and hole in the shooting direction, the deviation rate-How closed the projection area of the stem to the Critical Value of the Projection Area of Stem(CVA) as the test factors. The quality test results show that the accuracy of quality detection of plug seedlings depended mainly on the deviation distance and conveyor speed. Specifically, the accuracy of quality detection dropped to 85% and 91.10%, respectively, when the seedling deviated from the hole center by more than 10mm, and when the conveyor speed increased to 0.06m/s. But there was no significant impact when the projection area of the stem was close to CVA. In addition, the quality inspection test was carried out on 72 holes of Spathiphyllum plug seedlings. It was found that the recognition accuracy of the system reached 97.92%, and the productivity was 150 tray/h, and 10800plant/h, when the conveyor speed was 0.045 m/s and the deviation distance of seedling stem was within 10mm. This finding can provide a strong theoretical reference for the automatic evaluation of plug seedlings grading and quality inspection, particularly when adjacent leaves were covered.
    2021,37(20):202-210, DOI: 10.11975/j.issn.1002-6819.2021.20.023
    Abstract:
    Abstract: Extracting the phenotypic characteristics of Amygdalus mira seeds is to measure the size of a physical object that needs to operate a large number of peach seeds. However, some phenotypic data is still difficult to obtain at present. In this study, an automatic multi-feature extraction system was proposed for peach seeds using HSV color space and edge point detection. The system included three parts. The first part was the collection and image acquisition of Amygdalus mira seeds. Specifically, the Amygdalus mira seeds were collected from the scientific research institutions, and then seed images were captured using a small studio and digital camera. The second part was the image processing of peach seeds. First, the region of interest was obtained on the original image of peach seed, then converted from the RGB to the HSV color space. The threshold segmentation was then selected using the HSV space, in order to remove the seeds from the original image. The purpose of threshold extraction was to determine what threshold range of H space was used to segment the seed kernel and background and then determine the best segmentation of S space under the H threshold range. Finally, the V space threshold was selected in the threshold range of H and S space with the best segmentation, in order that all pictures were the same set of segmentation thresholds, further to realize the preliminary segmentation of peach seed. Binary morphological operations were then utilized to revise the under- and over-segmentation. The third part was the feature extraction and quantification of seeds. First, the morphological features were achieved, including area, shape index, and seed tip state. Specifically, the edge points of seed kernel images were detected to draw the fitting ellipse and separate the tip of seeds. Among them, the tip state was evaluated using the area and sharpness of the seed tip. Subsequently, the color and texture characteristics of the peach kernel were obtained using low-order moments and gray-level co-occurrence matrix. As such, the quantitative analysis was realized for the nucleus phenotype of Amygdalus mira seeds. Additionally, the extracted color features included the first-, the second-, and the third-order moments. The texture features included contrast, energy, homogeneity, and correlation. A comparative experiment was conducted to evaluate the RGB and gray threshold. It was found that the HSV threshold presented a better segmentation, indicating the highest accuracy rate (99.7%), average accuracy rate (98.9%), and IoU (97.4%). In addition, the extraction experiments of morphological, color, and texture features were carried out to further verify the performance of the system. The results showed that there were quite different phenotypic characteristics of different seed individuals. At the same time, the H-mean and S-mean moment showed a downward trend, as the color depth of seed gradually deepened, compared the extracted color features with the visual. The same comparison experiment was also performed on texture features. The contrast increased, while the homogeneity decreased gradually, as the depth of grooves on the seed increased gradually. The energy and correlation decreased gradually when the surface texture of seeds was much clearer. In summary, the extracted characteristics of color and texture were more consistent with that of the visual, indicating the quantitative texture of Amygdalus mira seed kernel. Consequently, this system can be expected to realize the extraction and quantification of kernel tip state, color, and texture features. The finding can also provide the data foundation and technical support for the breeding research of Amygdalus mira.
    2021,37(20):211-218, DOI: 10.11975/j.issn.1002-6819.2021.20.024
    Abstract:
    Abstract: A nutritious and healthy diet can be widely expected to reduce the incidence of disease, while improving body health after the disease occurs. The nutritional diet knowledge can be acquired mostly through the Internet in recent years. However, reliable and integrated information is highly difficult to discern using time-consuming searching of the huge amount of Internet data. It is an urgent need to integrate the complicated data, and then construct the knowledge graph of nutrition and health, particularly with timely and accurate feedback. Among them, a key step is to accurately identify entities in nutritional health texts, providing effective location data support to the construction of knowledge graphs. In this study, a BRET+BiLSTM+CRF (Bidirectional Encoder Representations from Transformers + Bi-directional Long Short-Term Memory + Conditional Random Field) model was first used with location information. It was found that the precision of the model was 86.56%, the recall rate was 91.01%, and the F1 score was 88.72%, compared with the model without location information, indicating improved by 1.55, 0.2, and 0.32 percentage points. A named entity recognition was also proposed to accurately obtain six types of entities in text: food, nutrients, population, location, disease, and efficacy in the field of human nutritional health, combining rules with BERT-FLAT (Bidirectional Encoder Representations from Transformers-Flat Lattice Transformer) model. Firstly, the character and vocabulary information were stitched together and pre-trained in the BERT model to improve the recognition ability of the model to entity categories. Then, a position code was created for the head and tail position of each character and vocabulary, where the entity position was located with the help of a position vector, in order to improve the recognition of entity boundary. A long-distance dependency was also captured using the Transformer model. Specifically, the output of the BERT model was embedded into the Transformer as a character-embedding conjunction word, thus for the character-vocabulary fusion. Then the text prediction sequence was obtained from the CRF layer. Finally, seven rules were formulated, according to the text characteristics in the field of nutrition and health, where the prediction sequence was modified according to the rules. The experimental results showed that the F1 score of the BERT-FLAT model was 88.99%. The BERT model combined with the word fusion performed the best, compared with that without the Bert model, indicating an effective recognition performance. Correspondingly, the named entity recognition model in the field of nutrition and health using fusion rules and the BERT-FLAT model presented an accuracy rate of 95%, a recall rate of 88.88%, and an F1 score of 91.81%. The F1 score increased by 2.82 percentage points than before. The finding can provide an effective entity recognition in the field of human nutrition and health.
    2021,37(20):219-225, DOI: 10.11975/j.issn.1002-6819.2021.20.025
    Abstract:
    Abstract: A passive acoustic technology has been widely used to monitor the behavior of aquatic organisms for the intelligent feeding system in recent years. Taking six sizes of Micropterus salmoides as research objects, this study aims to acquire the acoustic signals of pellet feeding in circulating aquaculture using passive acoustic techniques. The signals were first identified to classify for the post-processing using simultaneous audio and video recordings during feeding. The feeding activity was then quantified to extract and screen the characteristic parameters from the acoustic signals. Six kinds of pre-processing were utilized for the feeding sound signals, including A/D conversion, denoise, pre-emphasis, windowed framing, and endpoint detection. A Fast Fourier transform, real-time, and Mel frequency cepstrum methods were also used to extract the time- and frequency-domain features of each swallowing signal in the complete feeding acoustic signal, in order to obtain the correlation between each acoustic feature parameter and the swallowing order. Specifically, the swallowing interval, the peak-to-peak value of voltage, and the maximum amplitude were extracted from the time-domain features. It was found that the swallowing interval was positively correlated with the order of swallowing (R2>0.68), whereas, the maximum and range amplitude was negatively correlated with the order of swallowing (R2 <-0.61), but there was no significant difference between the correlation coefficient of three time-domain characteristic parameters. Furthermore, the maximum sum of power intensity and integral value was extracted from the power spectrum of each swallowing signal. Among them, P=0.05 was assumed as the basis to evaluate the integral value of power, where a more stable and reliable measurement was achieved for the characteristic parameters of feeding activity. In addition, the formant frequency and the average Mel cepstrum coefficient (AMFCC) were extracted to find each acoustic signal of feeding mainly in 4-7 kHz. More importantly, the third coefficient in AMFCC presented an outstanding and stable peak. Particularly, the feeding activity decreased significantly, as the feeding sequence increased. The extraction of power integral parameters depended significantly on subjective factors, although both time domain and frequency domain parameters presented an excellent correlation with the order of swallowing. The feature parameters of the time domain also behaved more reliable stability. Subsequently, the feature parameters for the activity of eating were screened out, according to the correlation between the acoustic feature parameters of ingestion and the order of swallowing. Correspondingly, the feature parameters of multi-feature fusion can be expected to better quantify the feeding activity, indicating the best choice for the swallowing interval and peak-to-peak value of voltage. The finding can also provide theoretical support to identify the sound signal of farmed fish in the intelligent feeding system.
    2021,37(20):226-233, DOI: 10.11975/j.issn.1002-6819.2021.20.026
    Abstract:
    Abstract: Maize is one of the main food crops in the world. The lodging of maize has posed a serious challenge on the yield and mechanized harvesting in modern agriculture. Current identification methods cannot fully meet the lodging resistance and long breeding cycle of maize varieties, due to the time-consuming and laborious tasks. In this study, hyperspectral imaging technology was combined with statistical learning to predict the lodging resistance of maize varieties during the vegetative growth period. A field trial was also carried out in 2018 and 2019. The hyperspectral images were then collected for the top leaves of 8 corn varieties with and without lodging resistance at the 9-leaf stage. The experimental procedure was as follows. A threshold segmentation was first utilized to identify the leaf area. The K-means clustering was then used to divide the leaf into three areas: normal reflection, dark reflection, and leaf vein area. The average spectral curve was finally extracted in the normal reflection area, in order to analyze the data characteristics of lodging-resistant and lodging samples. The Kennard Stone was selected to sort the sample data of each species. Two parts of the set sample were also divided, including the training and test set at a ratio of 3:1. The division of each variety was integrated into the final training and test set data, in order to obtain an evenly distributed dataset of each variety. As such, there were 378 training and 120 test set samples in the 2018 test, while there were 383 training and 120 test set samples in the 2019 test. The filtering feature selection Relevant Features (ReliefF) and Principal Component Analysis (PCA) were selected to mine the spectral classification features of lodging-resistant varieties and lodging varieties. Specifically, a different number of the nearest neighbors in ReliefF was set to determine some features, according to the stability of feature variables. The redundant features were often selected with a high correlation in adjacent bands. Correspondingly, the PCA was first performed on the spectral data, thereby selecting principal components without redundant features using the ReliefF. The classification models of ReliefF- Support Vector Machine (SVM) and PCAReliefF-SVM were established, where the original spectral data features were selected by the ReliefF, and the principal component features were selected by the PCAReliefF. The grid search was also selected to optimize the penalty and kernel parameters in the SVM model for a better prediction of the model. First, cross-validation was used on the training set data to optimize the number of selected features. 40 and 50 features in the trials in 2018 and 2019 were selected to build the model, in order to balance the accuracy of the model and the complexity of calculation. All the samples were then used in the training set, where the final parameters were used for model training. The accuracy rates of prediction in the PCAReliefF-SVM model were 85% and 85.83% in 2018 and 2019, respectively. In the ReliefF-SVM model, the prediction accuracy rates were 84.17% and 84.17% in 2018 and 2019, respectively. It indicated that the PCAReliefF-SVM model performed better prediction. The ROC curve was also used to evaluate the performance of the model. It was found that the ROC curve in the PCAReliefF-SVM modeling almost completely "enclosed" the ROC curve in the ReliefF-SVM, indicating a better performance of the PCAReliefF-SVM model. As such, hyperspectral imaging was used for the early classification of maize varieties, particularly for the overwhelm resistance. Consequently, the findings can provide a reliable idea for the maize resistance to overwhelm using spectral extraction, feature analysis, and modeling prediction.
    2021,37(20):234-247, DOI: 10.11975/j.issn.1002-6819.2021.20.027
    Abstract:
    Abstract: Abstract: Anhui Province of China is one of the most important agricultural production bases with abundant grain crop straw resources. It is necessary to clarify the temporal and regional characteristics of theoretical and crop residues for the differentiated development of fully quantitative utilization in straw sources in major grain-producing counties. Accurate evaluation of utilization potential to straw nutrient resources can essentially contribute to balancing the regulation of soil nutrients under straw returning. In this study, a systematic investigation was made on the spatiotemporal variation of wheat, rice and maize straw in major grain-producing counties of Anhui Province and utilization potential of a straw nutrient return to the field. The result showed that the total output of straw resources presented a slowly rising trend from 2011 to 2019. However, the straw production during 2011-2019 presented significant differences among three major grain crops, where the wheat straw firstly increased and then remained stable, while the rice straw was relatively stable with small fluctuation, and the maize straw showed an outstanding ascending. The theoretical amount of three main grain crop straws were 38.78 million tons in 2019, among which the wheat, rice, and maize straws accounted for 47.3%, 36.3%, and 16.4%, respectively. The wheat straw (73.0%) and maize straw (88.3%) were mainly concentrated in the North area of the Huai River. The rice straw was mainly distributed in the area between the Yangtze and the Huai River (41.7%), Western Anhui Province (21.3%), and the edge area of the Yangtze River (19.7%). The distribution of total straw yields from the three main grain crops in different agricultural areas was ranked as follows: North area of the Huai River (52.5%) ? Area between the Yangtze and the Huai River (24.3%) ? Western Anhui Province (10.5%) ? Edge area of the Yangtze River (9.1%) ? Southern Anhui Province (3.6%). The straw resources in 2019 were 13.38, 10.41, and 5.42 million tons for wheat, rice, and maize, respectively. The straw resources per unit sown area in the north area of the Huai River of Anhui Province were 4 505-6 310 and 4 171-5 395 kg/hm2 for wheat and maize, respectively. The rice straw per unit sown area were 4 487-5 326, 4 570-5 028, and 4 329-5 778 kg/hm2 for the Area between the Yangtze and the Huai River, Western Anhui Province and the Edge area of the Yangtze River, respectively. Furthermore, the contents of N, P2O5, and K2O were 0.253, 0.109, and 0.901 million tons, respectively, for the main grain crop straws in 2019. In the North area of Huai River of Anhui province, the nutrient inputs by wheat straw incorporation were N 35.8-50.1, P2O5 14.1-19.8, and K2O 139.8-195.8 kg/hm2, respectively, and the nutrient inputs under maize straw return scenario were N 42.7-55.2, P2O5 16.9-21.8 and K2O 93.4-120.9 kg/hm2, respectively. In the primary rice-growing regions (Area between the Yangtze and the Huai River, Western Anhui Province, and Edge area of the Yangtze River), the soil nutrient inputs from rice straw incorporation were N 38.0-50.8, P2O5 18.8-25.0, and K2O 151.6-202.3 kg/hm2, respectively. The finding can offer a great practical significance to improve the comprehensive utilization rate of straw resources, and further promote the green and high-quality development of agriculture for major grain-producing counties in Anhui Province of China.
    2021,37(20):248-255, DOI: 10.11975/j.issn.1002-6819.2021.20.028
    Abstract:
    Abstract: In recent years, under the guidance of China's green energy development strategy, a large number of photovoltaic, wind power and other DGs have been connected to the rural distribution network. The current rural distribution network structure, DG grid-connected location and capacity, line transmission capacity and other system conditions are in conflict with the ever-increasing rural power demand. DG output and load demand are continuously changing with time. The large-scale access of DGs and EVs has made the "source-load" side of the rural distribution network present significant uncertainty. The traditional topology of rural distribution network cannot cope with the impact of this "source-load" double uncertainty. Therefore, it is urgent to study a new method of dynamic reconfiguration for rural active distribution network. This paper establishes a dynamic reconfiguration model of active distribution network with DG consumption and line loss as objective functions. Taking into account the time-varying characteristics of "source-load", this paper proposes a new method of dynamic reconfiguration of rural active distribution network based on regional division, and designs the process of this dynamic reconfiguration method. In order to improve the efficiency of solving the problem of dynamic reconfiguration of active distribution network, a regional division method is proposed for the first time. The regional division method includes two parts: The initial division of regions and the optimized division of regions. The dynamic reconfiguration method of active distribution network based on area division mainly includes the following four steps. Firstly, the distribution network structure is divided into several initial regions which include main line regions and branch line regions based on the regional initial division method. Secondly, with the goal of promoting the flexible and efficient combined application of DGs between regions, the result of regional initial division is optimized dynamically based on the breadth-first traversal algorithm in the graph theory algorithm. Thirdly, based on the obtained results of dynamic regional optimization, the depth-first traversal algorithm is used to test and modify the DNR scheme to meet the topology constraints of the distribution network. At this time, all feasible DNR schemes can be obtained. Finally, the fast non-dominated sorting strategy is adopted to select the best network reconfiguration scheme that meets the constraints such as node voltage. To validate the performance of the proposed method, it is tested on the well-known IEEE 33-node and PG&E 69-node distribution system. The simulation result of 33-node distribution system shows that the loss reduction effect of the proposed method is very good. Especially at 14:00, the loss reduction effect of the distribution network was the most obvious, which was reduced by 71.41%. At this time, the effect of increasing the utilization rate of DG consumption is also obvious. On this basis, the proposed method on the consumption of each DG was deeply analyzed in this article. Result shows that the proposed method can achieve complete consumption of DG. The voltage of each node under the network structure obtained by the regional optimization division method meets the voltage quality requirements. In addition, the average daily DG consumption rate of the PG&E 69-node distribution system was increased by 16.09 percent point, and the daily line loss was reduced by 55.32%. The effectiveness of the proposed method is verified by the simulation of these two case studies. The simulation results show that the proposed method can fully switch and adjust the ability to improve the absorption capacity of the distributed power, reduce the line loss, suppress the fluctuation of the distributed power, and keep the node voltage smooth.
    2021,37(20):256-265, DOI: 10.11975/j.issn.1002-6819.2021.20.029
    Abstract:
    Abstract: In order to enhance the greenhouse design process and address the problems of incoherent information, repetitive modelling, frequent revision of drawings and manual extraction of quantities in the current greenhouse design process, this study proposes a BIM technology-based approach to the design of Venlo greenhouses. Firstly, the work to be done in the greenhouse design phase was specified. Based on the experience of BIM technology in other areas of construction, a systematic approach to the application of BIM technology at different stages of the design process of the Venlo greenhouse was analyzed, the software used to create the greenhouse BIM was selected, and a BIM-based workflow for the design, analysis, drafting and material statistics of the glass greenhouse was constructed. Furthermore, parametric component family were created by selecting different family templates according to the characteristics of Venlo greenhouse components, which formed a greenhouse component family library. Based on the workflow and the family library, a Venlo glasshouse for seedlings was designed. The design process consisted of schematic design, model creation and design output. In the schematic design phase, the site was arranged by using Revit's site and mass modules. With the help of Ladybug Tools, the visual analysis of the climate data of the site was carried out, the hours of direct sunlight on the winter solstice for greenhouses of different orientations was compared, and the direction of the greenhouse was determined. Additionally, operator was created in Grasshopper to process the meteorological data and the geometric data of the greenhouse to calculate the cooling and heating loads and the maximum ventilation of the greenhouse, which provided information for the determination of the equipment parameters. Finally, based on the Venlo greenhouse, during the model creation phase, elevation and axis networks were created in Revit for the positioning of the structural frame family according to the defined scheme. Automatically the structural analysis model was generated and exported to Dlubal RFEM through the software interface for displacement and strength verification, and the frame specification was adjusted according to the results. Afterwards, the components were deepened with open cuts from the Revit family module, the steel module and Advance Steel. Upon completion of the structural framework, other production systems such as the enclosure system, natural ventilation system and irrigation system were created in turn. Moreover, Navisworks provided a comprehensive check of the model and the systems were coordinated according to the generated collision detection reports. In the design output stage, drawings could be created quickly by adding comments to the views and dragging them into the title bar. Simple components were generated from the component view and complex assemblies such as trusses were created with Advance Steel. Material statistics were done separately by family category. Lastly, the model was imported into Lumion for rendering and animation with the help of a plug-in. In addition, A part of this study was applied in the design construction process of Yang'ling smart Greenhouse. The smart greenhouse BIM model was created, and a visual display of component installation was done, providing certain support for greenhouse installation.BIM technology breaks through the design chain, resulting in multiple use of one model, simultaneous analysis and automatic bill of materials statistics, reducing the workload of drawing changes and saving one-third of the time compared to current greenhouse design methods. BIM technology in the Venlo greenhouse sector can optimize the design process, strengthen the management and application of project information, enhance the efficiency and effectiveness of project construction, and offer a new design approach of positive significance to the industry.
    2021,37(20):266-276, DOI: 10.11975/j.issn.1002-6819.2021.20.030
    Abstract:
    Abstract: A diversified fallow ecological compensation is an inevitable choice for the sustainable development of agriculture in China. It is very necessary to explore the spatial distribution of fallow land for the higher efficiency of ecological compensation for fallow in arid areas. Taking the Kaidu-Kongque River basin in Xinjiang as an example, this article aims to propose different compensation strategies for different zones, thereby determining the spatial layout of fallow, considering the quality of cultivated land and risk of land degradation. The specific procedures were: 1) An evaluation index system of cultivated land quality was established to select the indicators from two aspects of soil physical and chemical properties, and cultivation convenience. A comprehensive evaluation was then made for the quality of cultivated land. 2) MEDALUS-ESAs model was selected to estimate potential risks of land degradation in the basin, where four indicators included soil, climate, vegetation and land use. 3) The Z-score was also applied for the quality score of cultivated land and risk index of land degradation. The standardized value was divided into four quadrants, according to the coordinate axis to determine the spatial distribution of fallow. Specifically, the cultivated land with "low quality and low risk" was classified as a priority fallow area, "high quality-low risk" was classified as a sub-priority fallow area, "low quality-high risk" was classified as restricted fallow areas, and "high-quality-high-risk" was classified as fallow area. 4) Different compensation strategies were finally proposed for fallow, according to different zones. The results showed that: 1) There was a fair overall quality of cultivated land in the whole Kaidu-Kongque River Basin, but slightly good in local areas. The spatial pattern of land degradation risk was "low in the northern, high in the southern". 2) The area of cultivated land located in the priority fallow area was 67 814.60 hm2, mainly distributed in the western part of Kongque River Oasis and the northeastern part of Bosten Lake. The area of cultivated land located in the sub-priority fallow was 71 784.94 hm2, mainly distributed in the northern part of the Kaidu River Oasis. The area of cultivated land located in the restricted fallow area was 80 576.89 hm2, mainly distributed in the central area of the Kongque River Oasis, the northern and southern part of Bosten Lake, and the eastern part of the Kaidu River Oasis. The area of cultivated land located in the forbidden fallow area was 107 358.03 hm2, mainly distributed in the southern part of Kaidu River and Kongque River Oases and the eastern Bosten Lake. 3) The cultivated land located in the priority fallow area was restricted by cultivated land quality. As such, the long-term fallow was necessary to combine with the quality improvement of cultivated land. The fallow compensation in the zone was determined, according to the loss of agricultural income and the cost of land improvement. Furthermore, the cultivated land located in the sub-priority fallow area was in good condition, where the fallow can be combined with agricultural water saving to implement seasonally fallow. More importantly, the fallow compensation depended mainly on the loss of agricultural income. The cultivated land in the restricted fallow area was restricted by cultivated land quality and ecological safety. Therefore, the fallow can be combined with cultivated land quality improvement and ecological protection to implement annual fallow, where the agricultural income loss, land improvement costs, and ecological protection costs standard should be considered into the fallow compensation.
    2021,37(20):277-286, DOI: 10.11975/j.issn.1002-6819.2021.20.031
    Abstract:
    Abstract: "Resource-asset-capital" attributes can be used to promote the efficient utilization and allocation of cultivated land against the market-oriented economy. Taking a typical Xundian County in mountainous areas of Yunnan Province as a study area, the quality evaluation and zoning management were made using the attributes connotation of "resource-asset-capital" and multi-source data of cultivated land. The targeted measures of local cultivated land management were also proposed for each zone using the local autocorrelation, according to the spatial agglomeration of quality evaluation. The results show that: 1) The resource attribute of cultivated land referred to the specific agricultural activities for the products from the cultivated land under certain natural conditions, such as light, temperature, water, soil, and heat. The asset attribute of cultivated land was that the cultivated land resources in social relations were able to bring benefits, thereby determining the ownership through the legal system. The capital attribute of cultivated land was that the cultivated land was traded and circulated in the market to obtain high profits. The resource, asset and capital attributes presented the influence on each other, indicating the only way for the value of cultivated land resources. 2) There were great differences among the geographical distribution and spatial pattern of resource, asset and capital quality of cultivated land. The resource quality of cultivated land showed less variation and more stable geographical distribution, compared with asset and capital quality. Furthermore, the resource quality of cultivated land in the study area presented a "high in the east and west and low in the middle" trend in spatial patterns. However, the asset and capital quality of cultivated land in the study area showed a "gradient decreasing towards the urban center" and a "high in the southeast and low in the northwest" pattern, respectively. 3) Taking the administrative village as the basic research unit, four areas were divided using the comprehensive spatial agglomeration, including the market-oriented pilot zone, market-oriented cultivation area, efficient upgrading area, and remediation concentration area. Differentiated management measures were also proposed for each zone. It is necessary to formulate and implement policies and regulations for the easy entry of high-quality cultivated land resources into the market for the market-oriented pilot zone. Further, the property rights system and the income distribution can be improved to ensure the rational circulation of cultivated land resources for the market-oriented cultivation area. The finding can provide a scientific reference for the protection and development of cultivated land management in the mountainous areas of Yunnan province.
    2021,37(20):287-294, DOI: 10.11975/j.issn.1002-6819.2021.20.032
    Abstract:
    Abstract: The ever-increasing needs for a better life have proposed much higher requirements for agricultural development, as socialism with Chinese characteristics has entered a new era. The Agricultural Green Development (AGD) has been the re-creation under the Sinicization for the concept of sustainable development. The construction of green development indicators for agriculture can greatly contribute to quantitatively valuating the AGD level, particularly for path exploration and policy-making. Accordingly, this study aims to first construct the evaluation index system of AGD in China. Then, the entropy, Principal Component Analysis (PCA), and Analytic Hierarchy Process (AHP) were applied to calculate the weight value of each indicator. As such, a combination weighting was used to calculate the final comprehensive weight value of each indicator to evaluate the AGD level in China from 2007 to 2019. Finally, a grey Verhulst model was adopted to predict the development trend in the 14th Five-Year Plan. The findings of this study revealed that China's AGD level showed a steady upward trend, and gradually moved towards the path of green development during 2007-2019. The comprehensive index of AGD rose from 26.20 in 2007 to 70.76 in 2019, with an average annual increase of 13.08%. Among them, the comprehensive index of AGD in 2017, 2018, and 2019 increased by 4.5%, 1.8%, and 5.1%, respectively, higher than the average level from 2013 to 2016. This was because, 1) a series of important policies were released to promote the AGD in recent years, including the relevant mechanism for AGD, the national AGD pilot zones, the supporting capacity of science and technology. 2) The agricultural development was oriented towards the path of green development during policy decision-making. More importantly, the weight value of the first-level index "Resource conservation and efficient utilization" was the largest (0.386), and the rest of the three first-level indicators were ranked in descending order "Policy support and science & technology support" (0.223), "Natural resources and ecological security" (0.212) and "High-quality products and affluence" (0.179). 3) China's AGD was predicted to enter the fast lane during the 14th Five-Year Plan, where the comprehensive index of AGD reached 77.9, an increase of 11.67% over 2019. It was also found that there were much larger weight values for the indicators of energy consumption per unit of agricultural output, carbon base productivity, and R&D investment intensity. It inferred that scientific and technological innovation can be an effective way to reduce resource consumption for higher efficient use, which was the power source for AGD. Therefore, three recommendations can be addressed during this time: 1) To further improve the system and mechanism of AGD; 2) To explore diversified agricultural and ecological compensation (e.g., carbon compensation), and 3) to strengthen the tackling of key green technologies (e.g., green technology for higher production and efficiency of crops, green and low-carbon planting and breeding technology). This finding can provide potential decision-making support to promote the AGD for the construction of the evaluation index system.
    2021,37(20):295-302, DOI: 10.11975/j.issn.1002-6819.2021.20.033
    Abstract:
    Abstract: The purpose of this research was to clarify the effects of monochromatic lights with different fixed bands on the post-ripeness regulation in typical respiration fruits. Specifically, a systematic investigation was made on the effects of red, orange, yellow, green, blue, and purple LED lights on delaying and accelerating low maturity bananas ripening during simulated storage and transportation at room temperature (20±0.7 ℃). The low maturity of bananas ripening and quality changes were observed under different colors of LED lighting treatment. The results showed that the >440-505 nm blue and 400-440 nm violet LED light greatly contributed to inhibiting the intensity respiratory of banana and release quantity of ethylene. Two colors of LED light were utilized to effectively delay the shelf storage time of banana for 2 days, while decreasing the color turn and decomposition of cellulose and starch. Subsequently, the final firmness of bananas under the blue and purple lighting treatment after 8 days was 2.5 and 0.1 N higher than the CK group. In addition, the total sugars content of bananas in the blue lighting group was 51.71% of CK. Hence, better preservation was achieved under the blue and purple LED lighting treatment, where the bananas post-ripening was inhibited to prolong the freshness preservation period. The >640-700 nm red and >605-640 nm orange LED lighting treatments were utilized to effectively promote 2 days earlier on bananas respiration and ethylene peak. In addition, the red light was used to increase the respiratory peak by 24.20% and the ethylene release peak by 23.97%, compared with the CK group. More importantly, the peel color of bananas turned more outstandingly under red and orange light, and the total color difference (ΔE) reached 94.7 and 83.25 at full ripeness. The red-orange light was also employed to stimulate the decomposition of starch and cellulose, thus speeding up the accumulation of bananas soluble sugar and softening. Therefore, it was found that both red and orange LED lights were selected to effectively accelerate the ripening of bananas. Among them, the orange light was used as an accurate of ripening, due to its intensity less than the red light. Additionally, the bananas exposed to yellow and green LED lighting showed premature rotting and post-ripening disorder. Moreover, the banana peels rotted seriously after 4 days, but the color differences (ΔE) of peels were 40.35 and 46.23 less than those of the CK group. Particularly, the>565-605 nm yellow and >505-565 nm green light also prevented the rapid decline of banana firmness, but accelerated the cellulose decomposition, compared with the CK group. At the same time, the pectin contents in the yellow and green light group were lower than those in CK. The changes of cellulose, pectin, and hardness varied in the groups. A comprehensive analysis was performed on the texture, sugar content, and respiration of bananas. It was found that the six LED light colors treatments were used to delay ripening, promote ripening and disturb ripening. Correspondingly, the red light was selected to promote banana ripening faster, the orange light to promote banana ripening slower, the blue light to inhibit post-ripening and delayed senescence better than purple light, the yellow and green light to disrupt the normal post-ripening of banana. In conclusion, monochromatic LED lighting can be widely expected to serve as physical preservation to delay or accelerate ripeness in the process of storage and transportation of bananas. This finding can provide a theoretical basis for the ripening regulation on more respiration fruits and vegetables.
    2021,37(20):303-312, DOI: 10.11975/j.issn.1002-6819.2021.20.034
    Abstract:
    Abstract: Hemerocallis fulva is one of the most popular flowers rich in bioactive substances, such as polyphenols, flavonoids, and alkaloids anthraquinones, particularly on antioxidant, antidepressant and anticancer. The extraction of phenolic compounds and antioxidant properties can also greatly contribute to the popularization of H. flower in the agricultural industry. However, only a few reports were focused on the extraction, forms and antioxidant activities of phenolic compounds in the H. flower. The present study aims to explore the effects of different extraction on the content, composition and antioxidant activity of phenolic compounds in various Hemerocallis flowers. Five kinds of flowers with different colors (yellow, orange, red-orange, jujube red, and bright red) were selected as raw materials. Three processing treatments (ultrasound, enzymolysis-ultrasound, and fermentation-ultrasound) were also utilized to determine the content of total flavonoids, total polyphenols, and scavenging rate of free radicals. Furthermore, high-performance liquid chromatography was adopted to identify the free, conjugated, and bound fractions of phenolic compounds, where the relationship was also established between phenolic compounds and antioxidant activity. Specifically, the types of total flavonoids and polyphenols were as follows: 'Hongyingwu', '63#', 'Jianzhuanglilan', 'Meiguixiniu', and 'Taiyangwu'. The results showed that there was a significant difference (P<0.05) of antioxidant activity in the different varieties of flowers, where the antioxidant activity was positively correlated with phenolic content. Furthermore, the antioxidant activities of flowers depended mainly on the varieties and extraction. More importantly, the vitamin C equivalents of DPPH (1,1-diphenyl-2-picrylhydrazyl) were 44.32, 40.63, 38.24, 37.64, and 35.60 mg/g, respectively, for the 'Hongyingwu', '63#', 'Jianzhuanglilan', 'Meiguixiniu' and 'Taiyangwu' under the fermentation-ultrasonic processing. The corresponding ABTS+ (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) vitamin C equivalents were 39.74, 36.24, 30.88, 28.38and 24.88 mg/g, respectively. The vitamin C equivalent of DPPH of 'Hongyingwu' increased from 38.24 mg/g by ultrasonic extraction to 41.49 mg/g by enzymatic ultrasonic extraction and 44.32 mg/g by fermentation-ultrasonic extraction. The vitamin C equivalent of ABTS+ of 'Hongyingwu' increased from 31.82 mg/g by ultrasonic extraction to 35.12 mg/g by enzymatic ultrasonic extraction and 39.74 mg/g by fermentation-ultrasonic extraction. Among the three fractions, the content of phenolic compounds in the free fraction was the highest, accounting for more than 75% of the total contents. Enzymatic hydrolysis and fermentation significantly (P<0.05) improved the contents of most phenolic compounds in the free fraction of 'Hongyingwu'. Particularly, the p-Coumaric acid was newly detected, while the free quercetin content after fermentation reached three times that of the original. The Vitamin C equivalent of DPPH and ABTS+ free radical scavenging rate of free phenols increased from 40.53 and 35.57 mg/g for ultrasonic processing to 48.20 and 47.40 mg/g for fermentation-ultrasonic processing, respectively. Correlation analysis demonstrated that the chlorogenic acid, caffeic acid, quercetin, and rutin in the free fraction were highly correlated with the antioxidant activity, indicating a great contribution to antioxidant activity. The finding can provide a theoretical basis for the development and utilization of H. fulva flower in functional foods and cosmetics.
    2021,37(20):313-322, DOI: 10.11975/j.issn.1002-6819.2021.20.035
    Abstract:
    Abstract: The collision of particles has been widely found in the processing of agricultural and food fields. The restitution coefficient of collision (RCC) of particles is one of the most important parameters to represent the behavior of particles after the collision. The responsive behavior of particles after the collision can also be predicted to obtain an accurate RCC of the particle after measurement. However, the RCC selection of particles still remained unclear, particularly on the limited function of devices and simplification in the application. Three RCC types are divided, including the restitution coefficient of kinematics, the restitution coefficient of kinetics, and the restitution coefficient of energy. The restitution coefficient of kinematics can be generally defined as the ratio of the velocities of particles before and after the collision. Since the variation in the velocity of particle collision can be caused by the forces on the particle, the restitution coefficient of kinetics is defined as the ratio of the momentums of restituted and extruded particles. Furthermore, two stages are divided in the process of particle collision using energy. In one stage, the particle is compressed and the energy of the particle would be absorbed. In another stage, the particle is restituted that the energy of the particle would be released. Subsequently, the RCC of particles needs to be calibrated to combine physical and simulation tests. As such, a physical experiment was performed on three types of RCC particles to verify the equivalence and applicability under different collision conditions. The Discrete Element Method (DEM) and Finite Element (FE) were also selected to simulate the interaction between agricultural particles and machinery. The influencing factors were summarized to improve the theoretical models, including the velocity and angle of particle collision, surface roughness of particle, temperature, and the material of particle. Thus, enhanced accuracy of predicted motion would be achieved for the particle after the collision. An attempt was also made on the applications of particle RCC in the theoretical model and numerical simulation related to mechanical parameters design. Consequently, it was found the resultant effect of different factors on RCC of particle, in order to enrich RCC of the particle under the real collision for the higher accuracy of the calculated. A promising prospect was also proposed from the multi-point collision of particles. A creative design of the device was also utilized to evaluate the RCC of particles. The finding can provide a strong reference for further investigation on the RCC of agricultural and food particles.
    2021,37(20):323-332, DOI: 10.11975/j.issn.1002-6819.2021.20.036
    Abstract:
    Abstract: A coarse cereal is one of the most important crops rich in nutrients. However, the frequently-occurred issues on food quality and safety have seriously endangered the trust in recent years, for example, the abuse of chemicals, heavy metals exceeding the standard, and harmful germs. Therefore, a traceability system is an urgent need for coarse cereals, in order to bridge the trust between farms and consumers, where the source of agricultural coarse foods can be rapidly traced through multi-party efficient collaboration. Most current traceability systems focus on recording data using bar or QR codes, radio frequency identification, and wireless sensor networks. But the tracing information is broken easily between upstream and downstream, leading to the blur transferred data, particularly on the long and scattered supply-chain of agricultural foods, including cultivation, processing, logistics, storage, and sales. Furthermore, the traditional traceability system cannot efficiently supervise the data records of each company, when quality and safety issues occur. As such, it is impossible to recall the problematic foods in time, much less to accurately locate the responsible party. Fortunately, blockchain technology can be utilized to integrate the distributed architecture, storage, and verification in the block, peer-to-peer network protocols, encryption, consensus mechanisms, identity authentication, and smart contracts. The data disclosure can also be used to enhance trust with fewer intermediate links. Therefore, this study aims to deal with the long supply-chain of coarse cereals, many trace entities, the differentiate share of data ledger, and the real-time monitoring of on-chain data. A novel traceability system was designed to implement the supervisable food products using the multi-chain architecture of blockchain and supply chain in coarse cereal. The forward and reverse traceability data was also collected ranging from the planting, processing, warehousing, transportation, and sales, using cameras, sensors, Beidou positioning devices, and IoT devices in real-time. Moreover, a systematic investigation was made on the business process and supervision characteristics of the supply-chain, as well as the full life cycle of coarse cereal. In addition, a new architecture of supervision-oriented multi-chain data storage was proposed for the actual production of coarse cereal. Specifically, the off-chain CouchDB state database was selected to store the key-value traceability data, particularly on the key-index instead of traversal query to improve the query efficiency. More importantly, a network access mechanism was designed using the regulatory authority, further to realize the collaborative supervision on- and off-chain through smart contracts. Correspondingly, blockchain technology was used to ensure the deep connection of various production factor resources with the real economy of coarse cereal. Anyway, the supply chain of coarse cereal integrated with the blockchain was utilized to strengthen the multi-party collaboration through mutual identity authentication, especially on data expansion, data sharing, and supervision. In terms of security, the average change rate of ciphertext in the enterprise network authorization diffusivity test was 82.53%, the average change rate of ciphertext in the enterprise network authorization correlation test was 82.39%, indicating higher security and less confusion. In terms of efficiency, the average time for consumers to query public traceability data was 0.415 s, and the average time for regulators to call cross-link port to query enterprise sensitive traceability data was 0.871 s. Furthermore, an actual traceability system was implemented to verify the model using Hyperledger Fabric for data privacy protection, data differentiation sharing, and the penetration supervision of traceability data, together with the real-time management, and control of traceability nodes. The in-depth mining was realized for the value of coarse cereal traceability big data, and sustainable development of the traced network. As such, farmers can receive professional or industrial policy guidance, whereas, companies can obtain the market trends and price conditions in real-time, and regulatory authorities can accurately control traceability data and transaction behavior. The finding can greatly improve the quality and safety of coarse cereal, production efficiency, and economic benefits.
    2021,37(20):333-338, DOI: 10.11975/j.issn.1002-6819.2021.20.037
    Abstract:
    Abstract: Salmonella enteritidis (S. enteritidis) infection has been recognized as one of the most common bacterial causes of human gastroenteritis worldwide, and was closely associated with eggs. Slightly Acidic Electrolyzed Water (SAEW), as an environmentally-friendly disinfectant, was often be studied in disinfecting eggshell surfaces to remove dirt and pathogenic microorganisms. However, the efficiency of SAEW was often be affected by the presence of manure. In our study, disinfection efficiency of SAEW in spraying treatment method was evaluated on manure and S. enteritidis mixture contaminated eggs, to verify if this method could be used to alleviate the interference of chicken manure on disinfection effectiveness. Eggs were first sprayed with different solutions (H2O、ERW and SAEW) to clean the manure in different times (6, 12, 18 and 24 s), and then sprayed with different disinfectants (H2O、ERW and SAEW) with different available chlorine concentration (ACC, 5, 15, 25 and 35 mg/L) in different times (6, 12, 18 and 24 s). Eggs were divided into 5 groups: H2O+H2O group (Sterilized H2O sprayed for cleaning and disinfection treatment), ERW+ERW group (ERW single sprayed for cleaning and disinfection treatment), ERW+SAEW group (ERW sprayed for cleaning treatment, then SAEW used for disinfection treatment) and SAEW+SAEW group (SAEW single sprayed for cleaning and disinfection treatment). The inactivation models of SAEW+SAEW and ERW+SAEW group with different ACCs, cleaning times and disinfection times were developed using multiple linear regression analysis. After treatment, decontamination of eggs with SAEW single sprayed group showed an equivalent or higher bactericidal effect compared to other treatments. A complete inactivation of S. enteritidis (6.26 lg cfu/egg) on the surface of shelled egg samples resulted from SAEW+SAEW group and ERW+SAEW group at an ACC of 25 and 35 mg/L for 18 and 24 s, respectively. Moreover, the established model of SAEW+SAEW and ERW+SAEW group had a good fit-quantified by the determination coefficient R2 (0.933 and 0.926) and adjusted R2 (0.930 and 0.923). The model was validated with additional random 8 conditions within the experimental domain. The predicted value showed a good agreement with the actual values, for the points of response values were very close to the line of 100% correlation. The model was valid and the results demonstrated that the cleaning time, disinfection time and ACC significantly affected the S. enteritidis. enteritidis reduction (P < 0.01). In addition, the ACC was ranked as the most important factor in the three factors by analysing the parameter coefficients in the model equation. As previously stated, manure was a strong limiting factor for disinfection of SAEW due to it can react with HClO in SAEW in an oxidative manner, resulting in a reduction of the ACC. From another point of view, it also meaned that manure could be effectively removed by the SAEW. Therefore, SAEW also has a good organic removal function as well as an excellent disinfection function. In conclusion, our results demonstrated that the SAEW could be used in disinfecting manure contaminated eggshell surfaces to remove S. enteritidis in single sprayed treatment way.
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    December 01, 2021 , DOI:
    Abstract:
    At present, the concept of green development is deepening and the social economy is undergoing comprehensive transformation. Realizing the green transformation of cultivated land use (GTCLU) is the key of agricultural modernization. GTCLU is a positive response to national development strategies such as green China and economic transformation, and is also an effective measure to solve the ecological dilemma of cultivated land use. However, such research is still lacking. This article presents and explains the concept of GTCLU, which guides cultivated land use activities through the idea of green development, and continuously improves the cultivated land use system with green development as axis. Moreover, the characteristics of GTCLU are summarized from four aspects: the category of transformation, the root causes of transformation, the manifestations of GTCLU and the evolution form of GTCLU. Combined with the concept and basic characteristics of GTCLU, analyzing the green evolution trend of cultivated land system from the perspective of micro production factors is a better starting point to study the efficiency of GTCLU in China. Therefore, the index system of GTCLU has been constructed scientifically. Thus, the article selects the panel data of 30 provinces in China from 2003 to 2017 to calculate the efficiency and its affecting factors of GTCLU by three-stage DEA-Malmquist model and Tobit model. The results showed that: 1) The efficiency of GTCLU calculated by Malmquist model is in a V-shaped growth trend of “declining first, then increasing”. In most years, the efficiency value is less than 1 and the green transition is invalid. 2) After removing the influence of environmental factors and random errors by the SFA regression of the second stage, the efficiency value of GTCLU obtained in the third stage is 1.001. This means that there is an obvious GTCLU in China and its degree is deepening. Technological progress is the main reason for efficiency improvement, while the technical efficiency change, pure technical efficiency and scale efficiency have become main bottlenecks for efficiency improvement. 3) There are obvious regional differences in the efficiency of GTCLU in China. The central region is the region with the best relative efficiency, followed by the northeast and eastern regions, and the western region is relatively the lowest. and its average annual growth rate is 0.84%. Meanwhile, the efficiency shows a fluctuating upward trend in time series, with an average annual growth rate of 0.84%. 4) Agricultural economic level, cultivated land resource endowment, government support and technology use intensity have significant effects on China’s GTCLU efficiency. In order to better promote GTCLU, it is necessary to pay attention to the system, management innovation and the promotion of resource endowment and technology. Meanwhile, each region should take the sustainable development advantage of cultivated land resource endowment, strictly control the low benefit agricultural economic development model, and fully release the vitality of green cultivated land market, which will become the driving force to promote China’s GTCLU. Cultivating the endogenous advantages of GTCLU by continuously strengthening the green elements in the input and output of cultivated land use are also important.
    November 24, 2021 , DOI:
    Abstract:
    In order to understand the reclamation status of Lianghuai coal mine area and its influence mechanism on soil microorganisms, reasonable manual intervention, and quickly and effectively improve the productivity of reclaimed soil, this study takes coal gangue filling reclaimed soil as the research object, adopts field investigation and sampling analysis. Illumina MiSeq high-throughput sequencing analyzes the V4 region of specific gene fragments of soil bacteria, based on non-metric multi-dimensional scale analysis, redundancy analysis, variance analysis, fertility index, and regression model methods. Biodiversity was explored to clarify the soil bacterial community and its response to soil fertility. The research results show that from the analysis of bacterial community composition, different reclamation directions have no significant effect on the distribution of bacterial dominant communities, and the proportions of different reclamation directions are different. Proteobacteria (32.42%~42.97%), Acidobacteria (10.47%~15.87%), Actinobacteria (8.90%~18.28%) are the main dominant bacteria groups. Among them, Proteobacteria occupies an absolute advantage, accounting for more than 30%. Alpha diversity shows that there is no significant difference in the abundance and diversity of bacterial soil samples in different reclamation directions. Shannon_Wiener index ranges from 5.23 to 6.91, Chao1 index ranges from 867.1 to 5436, and the Pielou index of each sample fluctuates around 0.8, Maintain stable changes. Beta diversity analysis showed that there was no significant difference in the composition of bacterial communities in different reclamation directions, and the composition of soil bacterial communities was negatively correlated with soil depth. The surface, middle, and deep soils have different soil bacteria living conditions such as moisture, aeration, temperature, and nutrients, resulting in differences in the composition of soil bacteria. The pH is consistent with the change of the diversity index, which affects the dominant microbial flora and biodiversity to a certain extent, but there is no significant difference in different reclamation directions. A one-way analysis of variance was carried out on soil fertility indexes of different reclamation directions, and it was found that the content of fertility indexes of surface soil was higher than that of bottom soil in general. Based on the evaluation of fertility index, the fertility quality is cultivated land >grassland>forest, and cultivated land is the best reclamation direction. Redundancy analysis shows that TN, SOM, AP and AK are the main fertility factors that affect the composition of soil bacterial communities, but some dominant bacterial communities do not respond to fertility factors significantly, which may be related to the high complexity of the soil microbial community and the regional conditions. The particularity and other factors are related. The regression model showed that the soil fertility index was extremely significantly positively correlated with the relative abundance of the Thaumarchaeota(P<0.01), and Streptomyces was significantly negatively correlated (P<0.05), and the correlation with the main dominant phylum was not strong. It may be caused by the complexity of the soil environment of the coal gangue reclaimed land. Based on the linear regression model and the functional effects of Thaumarchaeota and Streptomyces, the relative abundance of Thaumarchaeota and Streptomyces can be used as important biological indicators to evaluate soil fertility status. The research results can provide theoretical support for improving the fertility quality of Lianghuai mining area by filling the reclaimed soil with gangue at the microbial level.
    November 24, 2021 , DOI:
    Abstract:
    There are hydrophilic clay minerals kaolinite and hydromica in Benggang soil, which can produce obvious shrinkage and cracking phenomenon in the process of water evaporation. Because Benggang soil is a special soil with obvious stratification formed in the process of natural geological evolution, the shrinkage and cracking characteristics of different soil layers are obviously different. In order to study the influence of height-diameter ratio on soil shrinkage and cracking characteristics, this paper selected Benggang soil in Wuli Town, Tongcheng County, Hubei Province, and designed 10 groups of height-diameter ratio. During the experiment, soil samples were configures as supersaturated mud, and water evaporation was accelerated by low wind speed fans. The soil morphology changes before and after dehumidification were photographed at a fixed position, combined with digital image processing technology to carry out quantitative analysis, and discussed the shrinkage and cracking rules of Benggang soil under the condition of controlling height-diameter ratio. Results are as follows: (1) Among the four layers of Benggang soil, the radial shrinkage and cracks development characteristics in the transition layer are the strongest, while that of sandy layer is the weakest. In the vertical section of Benggang soil, the transition layer and sandy layer belong to the lower soil, and they are adjacent soil layer. The large difference between the two soil layers will seriously damage the stability and bearing capacity of Benggang, promote the collapse of Benggang wall. (2) The samples with smaller height-diameter ratio have significant cracks development, but the radial shrinkage is not obvious; the samples with larger height-diameter ratio have no cracks and the radial shrinkage is significant. Among them, the specific critical values of the height -diameter ratio of four soil layers by drying shrinkage cracking state transition to radial shrinkage state are respectively: 0.147~0.160, 0.160~0.183, 0.160~0.183, 0.134~0.147. (3) For the same soil layer, when the height-diameter ratio is same, even though the height and diameter are different, the crack parameters and radial shrinkage ratio are similar, and the axial shrinkage ratio increases with the increase of thickness. From the topsoil layer to transition layer, the crack morphology becomes more complex, and the sandy layer is not significant. (4) With the increase of height-diameter ratio, the shrinkage water content gradually increases, and the crack water content gradually decreases. The difference between the two can represent the tensile strength of the soil during the dehumidification process. The degree of shrinkage cracking, width-diameter ratio, radial shrinkage ratio increase with the increase of height-diameter ratio, while the other parameters show a decreasing trend. Among the four soil layers, the height-diameter ratio has the most significant influence on shrinkage cracking characteristics of transition layer, and the influence of sandy layer is the least. The research results show that the shrinkage and cracking characteristics of 4 soil layers of Benggang, and the influence of height-diameter ratio on shrinkage cracking characteristics. It can provide scientific basis for revealing the collapse mechanism of Benggang, and provide theoretical support for improving the stability of Benggang.
    November 23, 2021 , DOI:
    Abstract:
    To clarify the resources and environmental background of cultivated land and identify the priority areas of fallow in China, in this study, the Nemerow integrated pollution index, the groundwater level variation method, evaluation method of the importance of ecosystem service function and ecological environment sensitivity were used to systematically identify the spatial pattern and differentiation characteristics of ecological stress factors of China’s cultivated land from four dimensions, including status of soil pollution, arable land quality, over-exploited groundwater, and ecological protection red line delineation. And then a multi-criteria optimization of the fallow rule was constructed for identifying the scale of fallow and the spatial distribution of priority areas under the following three scenarios in China, priority to food safety (PFS), minimum production capacity loss (MCL), and priority to ecological security (PES). Especially, each fallow scenario sets low, medium, and high schemes for better prioritizing fallow units. Combining the three fallow scenarios to carry out spatial weighing of all factors to identify the fallow priority areas of cultivated land under resources and environmental constraints, ensuring ensure the optimal matching of the correlation between food production, food quality, and ecological security. The results showed that: 1) The area of arable land within the red line of ecological protection delineation in northern China is much higher than that in the south, and the area of arable land within the first-class and the second-class ecological protection red line delineation accounts for 3.57%, and 1.95%, respectively; 2) the ratios of farmland in China with slight, moderate and severe pollution were 18.56%, 2.31%, and 1.23%, respectively. The overall pollution in the south was higher than that in the north, while the south was partially scattered and the north showed a pattern of spot-like agglomeration; 3) the over-exploited groundwater areas were mainly concentrated in provinces of Hebei, Henan, Jilin, and Jiangsu, with severe over-exploited areas accounted for only 0.68% in total China. While the two provinces of Hebei and Henan have formed severe over-exploited areas with large-scale contiguous patterns, and the areas are 4670km2 and 3950km2, respectively; 4) the total proportions of arable land quality in the grade of the inferior and poor account for 3.69% and 14.0%, respectively, and the proportion of inferior or poor grade shows in northern China with the widely dispersed pattern was significantly higher than that in southern China. According to the comprehensive evaluation of China’s cultivated land ecological status and multi-criteria fallow rules, the total area of priority fallow areas accounted for 23.70%, of which the proportions of the prohibited-planting-fallow zone (I), restricted-planting-fallow zone (II), key-rotation zone (III) and general-rotation zone (IV) are 1.95%, 4.71%, 6.18%, and 10.86%, respectively. Compared with the three fallow scenarios of priority to food safety, minimum production capacity loss, and priority to ecological security, the total area of priority fallow areas is 8.40%, 4.18%, and 3.12% higher. This study shows it is necessary to clarify the background of cultivated land resources and the environment from the perspective of source governance to weigh the urgency of the fallow unit, and then provide technical support for the effective implementation of fallow planning, soil pollution controlling, and cultivated land protection technological innovation at the national level.
    November 22, 2021 , DOI:
    Abstract:
    Based on the analysis of human-earth system evolution of the watershed in Loess Plateau, this paper quantitatively explores the characteristics and rules of the temporal and spatial evolution of agricultural production function under the background of rural transformation and development. The Nianzhuang watershed, located in Baota County, Yan'an city, is chosen as the study area. The data comes from high resolution image interpretation and field surveys during five periods from 1985 to 2018. The results show that: 1) The quantitative diagnosis system of gully agricultural production function can effectively identify the spatial pattern of gully agricultural production function, and the dynamic evolution monitoring model can sensitively reflect the multiple evolution path of gully agricultural production function oriented by "economic-society" and "resource-ecology". 2) During the study period, the function space of gully agriculture in the study area has changed from traditional to modern production, and 2012 is the turning point of gully production function transformation. The traditional agricultural production function of gully is characterized by "small expansion - relatively stable - sharp reduction", while the modern agricultural production function of gully is characterized by "relatively stable - small expansion - sharp increase", and the functional diversity is increasing. The results provide a micro case of agricultural function transformation in the typical gully region of the Loess Plateau. 3) On the whole, the scope and intensity of the traditional gully agricultural production function show a decreasing trend. The functional space of modern gully agricultural production is continuously expanding, and the dominant direction is changing. Microscopically, the traditional agricultural production function takes the location of towns in the basin as the center, showing a concentric belt reduction. 4) The core goal of the high-quality development of gully agriculture in the Loess Hilly and gully region is to promote the "four turns", comprehensively build the "three cycles" model, promote the formation of a new pattern of industrial internal circulation in the Loess Plateau and its mutual promotion and development with the double cycles in the Yellow River basin, and further explore new kinetic energy and new ways to optimize agricultural production mode and innovate management mode. It is of practical significance to optimize allocation of regional land resources and the high-quality development of rural transformation.
    May 31, 2021 , DOI:
    Abstract:
    Accurate mapping of soybean planting area is of great significance to yield estimation, crop-damage warning and agricultural policy adjustments. But there are few reports on the application of remote-sensing technology in soybean identification in the areas with the high frequency of cloud cover, diverse summer crop types and complex field planting structure. Anhui Province is one of the main producing areas of soybean in China, this study selected Longshan and Qingtuan towns situated in typical soybean producing areas in North Anhui plain as the study area, and the hierarchical extraction strategy was proposed to obtain the spatial distribution of soybean planting area in the 2019 growing season based on the Sentinel-2 image which was acquired at the early pod-setting stage of soybean (August 18, 2019). Firstly, A set of decision tree filtering rules were established to eliminate non-agricultural cover types, i.e., water, sparse trees, bare soil and artificial objects (buildings, roads) and thus obtain the overall distribution of field vegetation. Then, 19 candidate features containing the reflectance of 10 spectral bands with a resolution of less than or equal to 20 m and 9 vegetation indices were generated based on the Sentinel-2 image to participated in the soybean extraction. With the support of typical ground-feature samples, ReliefF algorithm was used to evaluate the importance of each candidate feature, and three models i.e., ReliefF-RF, ReliefF-BPNN and ReliefF-SVM were established respectively by combining ReliefF with three machine learning algorithms including random forest (RF), backpropagation neural network (BPNN) and support vector machine (SVM) to screen out the most effective features for soybean identification and examine the performance of the three models in soybean mapping. The extraction effect was evaluated by unmanned aerial vehicle (UAV) images covering six ground samples (each was 1 km×1 km in size). Results showed that the ReliefF-RF model with Kappa ranging from 0.72-0.81 performed the best and the overall accuracy was between 85.92% and 91.91%. For each ground sample,the kappa coefficient was higher than the other two models (0.69-0.79 and 0.70-0.78 for Relief-BPNN and Relief-SVM, respectively); near-infrared B8 (842 nm), red-edge Normalized Difference Vegetation Index (NDVIre2) that derived from B8 and B6, short-wave infrared B12 (2190 nm), Red-Edge Position (REP), red-edge B6 (740 nm), green B3 (560 nm) and Enhanced Vegetation Index (EVI) were singled out by the ReliefF-RF, which indicated that these seven optimum features were more advantageous than other commonly used spectral bands and remote-sensing vegetation indices in soybean identification, and the importance of red edge-related variables was particularly highlighted. In addition, the mapping result derived from the optimum features significantly outperformed which generated from the 10 spectral bands. Although the performance of optimum feature-subset was slightly inferior to total 19 features, ReliefF-RF that contained only seven optimum features showed obvious advantages in terms of time and computation cost, as well as data volume. The hierarchical extraction strategy only focused on field vegetation, the optimum features generated by the strategy were more targeted and were not affected by the proportion of other non-agricultural land cover types, it should have better applicability and generalization in theory. The findings of this study would provide a valuable reference for the soybean extraction in areas under complex planting conditions.
    May 12, 2021 , DOI:
    Abstract:
    Wolfberry (Lycium barbarum) is a traditional Chinese medicinal and edible plant. It contains a variety of functional ingredients and has various functional activities such as anti-aging, immune regulation and anti-atherosclerosis. Hubei hybrid wolfberry is a researcher who induced and doubled Ningxia wolfberry, and then crossed it with the local wild wolfberry in Hubei, and was later introduced to Jianshi County, Enshi Prefecture. It has become one of the important industries in the local poverty alleviation. Compared with Ningxia wolfberry, Hubei hybrid wolfberry has a higher moisture content. The previous study found that it is not suitable for processing into traditional dried wolfberry products. It is urgent to develop new processed wolfberry products to improve the conversion rate of Hubei hybrid wolfberry and the economic benefits of the industry. Using lactic acid bacteria to ferment characteristic fruits can not only give the product a unique flavor, but also transform or increase the types and content of active substances in it, and improve the nutritional value and health benefits of the product. However, there are few reports on the effects of different lactic acid bacteria fermentation on the nutritional quality of wolfberry juice. Therefore, this study used Hubei hybrid wolfberry as raw material and used 6 kinds of lactic acid bacteria (Lactobacillus plantarum, Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus casei and Lactobacillus fermentum) for fermentation. The physicochemical properties, main active components and antioxidant activity in vitro of wolfberry juice before and after fermentation were studied. And establish a method to comprehensively evaluate the quality of fermented wolfberry juice using principal component analysis, in order to select the most suitable lactic acid bacteria strain for wolfberry juice fermentation. The results showed that the 6 kinds of lactic acid bacteria could grow well in wolfberry juice, which the viable count can reach above 10.0 Lg CFU/mL. After fermentation, the total sugar and reducing sugar content in the juice is significantly reduced (P <0.05). Lactobacillus plantarum and Streptococcus thermophilus has better acid production capacity, and the total acid content had 6.74 g/kg and 6.07 g/kg. Compared with unfermented wolfberry juice, the total phenol content in wolfberry juice fermented by Lactobacillus plantarum, Streptococcus thermophilus, Lactobacillus rhamnosus and Lactobacillus fermentum increased by 13.76% to 28.07%, while there was no significant difference in the content of total phenols in goji juice fermented by Lactobacillus acidophilus and Lactobacillus casei (P>0.05). And the total flavonoids content increased by 55.80% to 161.97% after fermentation. The antioxidant activities of fermented wolfberry juice were also significantly improved (P<0.05). Correlation analysis results show that the increase in antioxidant activity is significantly related to the content of total phenols and total flavonoids. Based on principal component analysis, three principal components were extracted, covering three levels of fermentability, nutritional quality, and functionality. They comprehensively reflect the quality of fermented wolfberry juice. The cumulative variance contribution rate is 82.344%. The comprehensive score ranking shows that the quality of wolfberry juice fermented by Lactobacillus plantarum and Lactobacillus fermentum is better, and they are suitable as a starter for developing high-value green processed beverages of wolfberry.
    May 12, 2021 , DOI:
    Abstract:
    Abstract: Solar greenhouse has been widely used in China, and improving the heat storage and release ability of the rear wall of solar greenhouse has always been a research hotspot. The application of PCM in solar greenhouse wall can effectively improve the heat storage and release performance of the wall. Three PCM walls were studied in this experiment. First we tested three kinds of phase change materials in laboratory ability of heat accumulation of single block cement module. The heat storage per unit volume of F1 cement module increased from 6.4℃ to 35℃ is 92.6MJ/m3; the temperature of F2 cement module increased from 7.6℃ to 35℃,the heat storage per unit volume is 102.1MJ/m3; the temperature of F3 cement module increased from 8.3℃ to 32°C,The heat storage per unit volume is 95.1MJ/m3. The temperature of F1 cement module decreases from 35℃ to 5.4℃ and the heat release per unit volume is 75.8MJ/m3; the temperature of F2 cement module decreases from 35℃ to 5.9℃ and the heat release per unit volume is 92.5MJ/m3; the temperature of F3 cement module decreases from 32℃. The heat release per unit volume to 7.8°C is 84.2MJ/m3. Under sunny conditions in winter, the heat storage per unit area of the 0.08mF1 wall is 4469.0kJ/m2; the heat release per unit area is 2343.2kJ/m2; the heat storage per unit area of the 0.08m thick F2 wall is 4571.0kJ/m2. The heat quantity is 3214.6kJ/m2; the heat storage per unit area of 0.08mF3 wall is 4830.7kJ/m2, and the heat output per unit area is 3960.9kJ/m2. Compare with the heat storage and release performance of other wall materials. The heat storage per unit area of the 0.6m thick soil wall is 3357.2kJ/m2, and the heat release per unit area is 811.7kJ/m2. When the wall thickness is only about 14% of the soil wall, the heat storage performance of F1, F2 and F3 is better than 0.6m soil wall, the gap is obvious, 0.08m F1, F2, F3 phase change material cement module unit The area heat storage is 1.3 times, 1.4 times and 1.4 times that of the 0.6m soil wall; the heat release performance gap is even greater. The 0.08m F1, F2, F3 phase change material cement module emits 2.9 heat per unit area of 0.6m soil. 2.9 times, 4.0 times and 4.9 times the wall. The 0.48m red brick wall stores 5490 KJ of heat per unit area during the day and 2140kJ/m2 of heat per unit area. The three types of heat output per unit area also have huge advantages. Therefore, we applied the phase change material cement module to the solar greenhouse on a large scale. The total area accounts for about half of the wall area. The results show that the phase change material wall absorbs a large amount of excess heat inside the greenhouse during the day on a sunny day in summer. F1 The wall absorbs a total of 35614.8KJ of heat, the F2 wall absorbs a total of 72788.4kJ, and the F3 wall absorbs a total of 57153.6kJ; the three absorb a total of 165556.8kJ and emit 72718.8kJ at night; summer is cloudy, the F1 wall totals Absorb heat 1,2589.2KJ, F2 wall absorbs a total of 24310.8kJ, F3 wall absorbs a total of 22338.0kJ; the three absorb a total of 5,9238.0kJ, and emit 37809 kJ at night; on sunny days in winter, the phase change material wall absorbs during the day Heat, the three absorb heat 203158.2kJ and release a lot of heat at night, F1 wall releases a total of 36442.8KJ heat, F2 wall releases a total of 49993.2kJ heat, F3 wall releases a total of 51333kJ kJ of heat, and releases heat at night 137769kJ; On cloudy days in winter, the phase change material wall absorbs heat during the day. The three absorb heat 117,069kJ and release a large amount of heat at night. The F1 wall releases a total of 1,7035.2KJ, the F2 wall releases a total of 37260kJ, and the F3 wall releases a total of 37260kJ. The heat is 49542kJ kJ, and the heat is 103837.2kJ at night.Applying phase change materials to sunlight greenhouses, with the aid of natural ventilation measures in summer, can absorb a lot of heat, effectively reduce the temperature peak of the greenhouse, and release a lot of heat in winter to increase the night temperature of the greenhouse. This also provides new ideas and solutions for improving the greenhouse environment and regulating temperature.
    May 12, 2021 , DOI:
    Abstract:
    The parcel-based crop distribution can clearly reflect the detailed information including farmland location, boundary and crop type. It has high significance to demands such as precision agricultural management, payment of planting subsidies and agricultural resource survey. Although the collaboration of multi-source high-spatial and high-temporal resolution satellite images provides an effective way to realize the parcel-based crop mapping, there exists deficiencies in farmland parcel extraction and temporal feature construction. Based on previous studies upon spatiotemporal collaboration, the present study implements parcel-based crop mapping by following steps: 1) extract parcels based on the 0.6m high-spatial-resolution Google Earth images using D-LinkNet deep learning model; 2) construct time series data set for each parcel by using multi-source observations from Landsat8 and Sentinel-2 satellite, and utilize clear data tiles from images with high cloud cover; 3) reconstruct parcel-based NDVI time series through weighted Double-Logistic fitting method, and extract phenological metrics such as time of starting of growth, time of ending of growth, duration of growth cycle, and calculate spectral indexes from Landsat8 and Sentinel-2 multispectral data; 4) select features using mean decrease accuracy (MDA) indicator, train random forest classification model using crop type data collect from ground experiment, and make parcel-based crop mapping of the study area. The study area is Fusui County in Guangxi Zhuang Autonomous Region. The study area is cloudy and rainy, with rainfall days about 130~220 days, Its topography is diverse and complex, with high degree of land fragmentation. Its planting structure is relatively complex. The dominated crops include sugarcane, paddy rice, banana and orange. The results show that the farmland parcels are well extracted by using D-LinkNet deep learning model, with the edge accuracy of 84.54% and the producer accuracy of 83.06%. On the contrary, the normal multi-scale segmentation method segments the whole image and resultant parcels interferes the extraction of crop distribution. The reconstructed NDVI time series of sugarcane, paddy rice, and banana can clearly reflect phenology. NDVI of sugarcane and paddy rice increases and decreases significantly. The growth season of sugarcanes starts from March to the following March. The growth season of paddy rice lasts for about 3~4 months, and its NDVI time series changes the most intensely. The reconstructed NDVI time series of evergreen eucalyptus and orange shows relatively steady throughout the year. The eucalyptus with high vegetation cover shows high NDVI values during the observation period. The MDA indicator is used to estimate the feature importance. It shows that images acquired in summer and autumn are better for crop classification in the study area, Sentinel-2 red-edge features and phenological features are important to crop classification. Combining the phenological and spectral features can reach the best classification performance. In Fusui County, the overall classification accuracy reaches 88%, and the accuracy of sugarcane reaches over 95%. The crop mapping results shows that sugarcane is spatially distributed around the whole study area, including plaining areas and mountainous areas. The planting area of sugarcane accounts for nearly 70% of the farmland areas, orange accounts for 18.6%, and paddy rice accounts for 7.12%. The paddy rice is near the settlement places. The study successfully extracts phenological features by using Landsat8 and Sentinel-2 multi-source observations, and verifies the importance of phenological features in the parcel-based crop distribution extraction. This research theoretically constructs a model to make parcel-based crop classification by collaborating high spatial and high temporal satellite data, and can provide a set of practical technical scheme for acquiring parcel-based crop distribution.
    May 12, 2021 , DOI:
    Abstract:
    Fluorescence has unique luminescence characteristics. The combination of excitation light and emission light can greatly reduce the interference of background signals and greatly improve the sensitivity of the detection system. Many scholars at home and abroad obtain the optimal excitation wavelength and optimal emission wavelength of the analyte based on the principle of photoluminescence of fluorescent substances, and have developed miniaturized, low-cost dedicated instruments. However, the existing portable instruments still focus on detecting pesticide residues in the solution system, and there are fewer instruments for directly detecting pesticide residues on the surface of vegetable leaves, which cannot meet the requirements of on-site rapid detection in modern agricultural production and life. Therefore, in view of the problems that the existing pesticide residue detection instrument can only detect the pesticide residue in the aqueous system and the detection object was relatively single, the pesticide residue of acetamiprid on lettuce leaves were studied in this paper. The feasibility of modeling pesticide residues and fluorescence intensity on the leaf surface was explored, and a portable detection instrument for pesticide residues on the leaf surface was designed by optimizing the light path structure to suppress the interference of stray light on the leaf surface. Firstly, through experiments, the best excitation wavelength and best emission wavelength of acetamiprid pesticide in standard solution and three plant leaves were at 350 and 500 nm, respectively. An LED with a central wavelength of 350nm and a maximum drive current of 100mA was selected as the excitation light source, and a photodiode with a peak response range from 480nm to 580nm was used as the photoelectric detection device. A filter with a center wavelength of 500nm was used to prevent the passage of other interference light, and only the emission wavelength of the acetamiprid pesticide was allowed to pass to reduce the interference of the secondary spectrum. Then, the optimal parameters of the optical path are determined. By fluorescence experiments, it was found that when the light Angle was 45°, the fluorescence intensity excited by acetamiprid pesticide on the leaf surface was the highest. By calculating the optical path size, it was found that when the direct distance from the LED laser source to the blade was 4.89cm and the vertical distance was 3.46cm, the illumination of the blade was the largest. In addition, in view of the diffuse reflection problem of the light source illuminating the surface of the blade, a diffuse reflection device was designed to achieve the maximum absorption of light energy. Moreover, according to the requirement of weak fluorescence signal detection, the corresponding control circuit, driving circuit and detection circuit were designed. A signal detection system was designed with STM32 chip as the main control chip to collect the voltage signal of the detection circuit, and the pesticide residue value was calculated according to the working curve of pesticide residue value. The PWM wave was output to modulate the LED light source and the difference between the frequency of detecting light and the frequency of ambient light can suppress the interference of ambient light to the light source. Then, SPI and I2C communication protocols were used to communicate with AD acquisition chip and OLED display screen to realize real-time detection of pesticide residues and real-time display of pesticide residues. Finally, the calibration equation was established and a portable detector was designed to detect pesticide residues. The measuring instrument was calibrated and tested, and the measuring value relation model of the portable measuring instrument was established. The determination coefficient of the model reached 0.875. The portable fluorescence spectrometer designed in this study can quickly, accurately and non-destructively detect pesticide residues on the surface of leaves, which provided a reference for the development of a more universal portable detection instrument.
    April 08, 2021 , DOI:
    Abstract:
    In order to analyze the energy consumption of the piped spiral flow hydraulic transportation of tube-contained raw material, the setting angle of the guide bar was the main control variable, and the method of combining theoretical analysis and model tests was adopted to study the spiral flow velocity characteristics on cross-sections between the two piped carriages under conditions of different setting angles of the guide bar in this paper. The results show that the axial velocity distribution trend on cross-sections between the two piped carriages is basically the same under the conditions of different the setting angles of the guide bar, and both show the distribution characteristics of spreading inward from the pipe wall and then outward from the pipe axis. The axial flow velocity value on each section between the two piped carriages is overall large, with the maximum value reaching 3m/s. The radial velocity on cross-sections between the two piped carriages under conditions of different setting angles of the guide bar basically fluctuated between ?1.0-1.0 m/s, and the area where the radial velocity value was 0 was relatively large. With the increase of the setting angle of the guide bar, the radial flow velocity on cross-sections between the two piped carriages gradually showed a 120° rotational symmetry distribution. In the directions of 0°, 120°, and 240° polar axes, the radial velocity value was smaller. Compared with the axial and radial velocity, the circumferential velocity was most affected by the setting angle of the guide bar, and the intensity of the circumferential velocity increased with the increase of the setting angle of the guide bar, and its maximum value could reach 1.5m/s. At the same time, with the increasing of the setting angle of the guide bar, the circumferential velocity of the counter clockwise rotation along the circumferential tangent increased. Similar to the radial velocity, with the increase of the setting angle of the guide bar, the circumferential flow velocity on cross-sections between the two piped carriages gradually showed a 120° rotational symmetry distribution, but the circumferential flow velocity was larger in the directions of 0°, 120°, and 240° polar axes. The study can not only improve the theories of pipeline spiral flow, but it can also provide theoretical reference for the popularization and application of the piped hydraulic transportation technique of tube-contained raw material.
    April 08, 2021 , DOI:
    Abstract:
    In respect of pig instance detection, the application of traditional computer vision techniques is constrained by sundries barrier, overlapping, and different perspectives in the pig breeding environment. In recent years, the attention-based methods have achieved remarkable performance. It can increase the weight of regional information that is beneficial to instance detection, and suppress secondary information to improve model effects. We select a total of 45 live pigs aged 20 to 105 days in 8 pens as the research object. We use a head-up angle of view to collect a total of 3834 labeled images and divide it into 2490 as the training set, 480 as the validation set, and 864 as the test set. we introduce two types of attention units into the feature pyramid network (FPN) framework, which encode the semantic interdependencies in the channel (named channel attention unit(CAU)) and spatial (named position attention block (PAU)) dimensions, respectively. By integrating the associated features, the CAU selectively emphasizes the interdependencies among the channels. Meanwhile, the PAU selectively aggregates the features at each position through a weighted sum of the features at all positions. A dual attention unit (DAU) is proposed to integrate CAU features with PAU information flexibly. We select the two backbone networks as ResNet50, ResNet101 and the four major task networks as Mask R-CNN, Cascade Mask R-CNN, MS R-CNN and HTC cross-combination model to detect the performance of group breeding pigs. In comparison with such state-of-art attention modules as convolutional block attention module (CBAM), bottleneck attention module (BAM), and spatial-channel squeeze & excitation (SCSE), embedding DAU can contribute to the most significant performance improvement in different task networks with distinct backbone networks. Especially with HTC-R101-DAU, compared with HTC-R101-CBAM, the performance is increased by 1.7, 1.7, 2.1, and 1.8 percentage points at AP0.5, AP0.75, AP0.5:0.95, AP0.5:0.95-large respectively; Different backbone networks have a certain impact on the pig detection effect of the same task network. In the task network without any attention unit, the detection effect of R50 is better than R101, but after adding any attention unit, the detection AP values of the two backbone networks are relatively close. In order to separately explore the influence of channels and positions attention units on task network detection performance, the CAU and PAU are added for comparative analysis. Experiments show that DAU is comparable to CAU and PAU, it can obtain better AP index values, shows that the simultaneous fusion of two dimensions of attention information can complement each other to improve the accuracy of position detection. In addition, compared with CAU, adding a specific number of PAU units can generally achieve better AP index values; In order to obtain pixel-level dense context information, we explore the number of series PAU units for the impact of the detection results, a position attention module with 1 to 4 PAU units connected in series was constructed. Experiments show that under the same experimental conditions, the predictive results appear a trend of increasing initially and decreasing afterwards after different numbers of PAU are merged; Comprehensive analysis, the HTC-R101-DAU model can more accurately and effectively detect live pigs in different scenes, and it can lay the foundation for the follow-up in-depth study of pigs.
    April 08, 2021 , DOI:
    Abstract:
    The water level of coastal wetlands is of great significance to the development of coastal economy and the growth of mangroves. At present, the mainstream method of obtaining water level still relies on hydrological stations to monitor regularly and at fixed points. This method has high monitoring costs and does not meet the requirements for timeliness. The rapid development of satellite altimetry technology allows it to be used as a supplement to ground monitoring. This study takes the coastal wetland of the Beibu Gulf in Guangxi as the research object, uses the daily Jason-3 and Sentinel-3A altimetry data from 2016 to 2020 as the data source, and calculates the initial coastal wetland water level value through the basic radar altimetry toolbox The principle of triple-middle error is used to eliminate outliers to obtain the initial coastal wetland water level. Because the impact of land will pollute the nearshore waveforms, thereby reducing the measurement accuracy, in order to further improve the reliability of the measurement, first import the obtained initial coastal wetland water level points into the Omap, and remove the water level data falling on the land and vegetation coverage areas. Then, four re-tracking algorithms of gravity center shift method, threshold value method, improved gravity center shift method and improved threshold value method are used to re-calibrate the height measurement water level to obtain the corrected water level of the coastal wetland. The coefficient of determination, RMSE and MAE are selected to quantitatively evaluate the accuracy difference of the two altimetry satellites using different algorithms to extract the water level of the coastal wetland. High-precision altimetry satellites are selected to explore the intra-year and inter-annual dynamic changes of the coastal wetland water level, using the intra-year water level variation, monthly average water level, seasonal average water level, and annual average water level for analysis. The research results show that the four re-tracking algorithms can extract the water level of coastal wetlands, and the improved threshold method has the best re-setting effect. The maximum coefficient of determination obtained by Jason-3 is 0.78, the minimum RMSE is 0.35m, and the minimum MAE is 0.28m; the maximum coefficient of determination obtained by Sentinel-3A is 0.87, the minimum RMSE is 0.24m, and the minimum MAE is 0.18m. The results show that the monitoring accuracy of Sentinel-3A is high. The water level change of the Beibu Gulf coastal wetland in Guangxi from 2016 to 2020 shows obvious seasonality. The average water level change during the year is 3.37m, and the water level changes more drastically, showing a downward trend as a whole, with an average annual change rate of 0.005 m/a. The spaceborne radar altimeter provides a powerful method for monitoring the water level of coastal wetlands on a large scale, which is of great significance to the study of coastal wetland changes and ecological environment protection.
    March 19, 2021 , DOI:
    Abstract:
    Ecological security pattern (ESP) is considered to be one of the important spatial approaches to alleviate the contradiction between ecological protection and economic development, and is also the basic premise to ensure regional ecological security and maintain social sustainable access to ecosystem services. In recent years, coupling multiple ecosystem services has gradually become a new research direction of ESP. Generally speaking, previous studies have assumed that different ecological processes do not interfere with each other and that there is no trade-off relationship between ecosystem services. In the process of ecological node identification, it is often ignored to identify the ecological obstacle points that hinder the movement or communication between organisms and the ecological pinch points that are more likely or very frequent in the process of biological migration. The Yellow River Basin is not only the main birthplace of Chinese civilization, but also an important ecological barrier in China. It is of great practical significance to identify the patches and corridors that have an important impact on regional ecological security, optimize the ecological space, and improve the ecosystem service function for the realization of high-quality development of the basin. Based on the five typical ecosystem services of food supply, carbon sequestration, oxygen release, water production and soil conservation in Gansu section of the Yellow River Basin in 2019, this paper simulated the ecosystem service priority protection areas of the study area in 2019 as the ecological source areas using multi-scenario ordered weighted averaging (OWA) model. The minimum cumulative resistance model is used to construct the basic resistance surface, and the circuit theory model is used to extract the ecological corridor and identify the ecological pinch points, so as to construct the ESP of Gansu section of the Yellow River basin with the ecological source as the core, the ecological protection priority areas with different gradients as the benchmark framework, and the ecological corridor pinch points as the axis, and optimize the ecological space. The results show that: there are 169 ecological source patches in the study area, with an area of 27460.56 km2, accounting for 19.2% of the total area of the study area. The five ecosystem services in the study area show a collaborative relationship from an overall perspective. The three natural boundary regions of Gannan Plateau, Longzhong Plateau and Longdong Loess Plateau are affected by topographic climate, vegetation cover and human activities, and the differences and similarities of ecosystem services in different regions will occur. Through the different combination of rank weight, seven kinds of ecosystem service protection schemes are provided, which make the extracted priority reserve have the core and comprehensiveness of ecological sources, so as to achieve the goal of high efficiency and balanced allocation of ecosystem service protection. Considering the trade-off degree (0.935), the priority conservation areas under scenario 4 were selected as the ecological source of the study areas. The minimum cumulative resistance model is used to identify the ecological corridor, and the circuit model is introduced to identify the spatial scope of the ecological corridor. A total of 441 ecological corridors with a length of 6774.9 km were identified in the study area. By calculating the current density of the ecological corridor, 49 ecological pinch points were identified. It is proposed to construct the optimization system of ecological safety space layout in Gansu section of the Yellow River Basin with "four axes, six regions and multiple centers", and to form a functional and networked regional ecological space optimization structure. The results can provide decision support for sustainable management and ecological management optimization of the upstream ecosystem of the Yellow River Basin.
    February 24, 2021 , DOI:
    Abstract:
    In order to explore the pyrolysis characteristics and synergy of single and mixed samples of corn stalks and municipal sludge, based on thermogravimetric analysis, at different heating rates (10℃/min,、20℃/min, and 30℃/min), the Corn stalks, municipal sludge and their mixed samples (mass ratio 9:1, 3:7, 5:5, 7:3, 1:9) were used for thermogravimetric test, and Coats-Redfern integration method was used to study kinetic characteristics . The results show that the difference in pyrolysis characteristics of corn stalks and municipal sludge is large, the residual rate differs by 18.57 percentage points, the comprehensive pyrolysis index differs by 35.73×10-05, and the activation energy E differs by 35.31kJ/mol~46.88kJ/mol. With the content of municipal sludge from 10% to 90%, the initial pyrolysis temperature decreased from 360.3℃ to 440.3℃, the main pyrolysis interval of mixed samples became longer from 277.7~360.3℃, and shifted to the high temperature zone. The residual rate increased from 33.69% to 45.83%, the maximum weight loss rate decreased from 7.88%·min-1 to 3.11%·min-1, and the comprehensive pyrolysis index decreased from 8.5×10-05 to 1.7×10-05. It shows that the municipal sludge improves the pyrolysis starting temperature of mixed samples, but at the same time it also widens the pyrolysis interval, increases the residual rate, slows the weight loss rate, and decreases the comprehensive pyrolysis index. The comprehensive pyrolysis index (D) of mixed samples is lower than the corresponding theoretical value to varying degrees, indicating that the co-pyrolysis of the two has an inhibitory effect. The activation energy required for the individual pyrolysis process of corn stalks is greater than the activation energy required for the individual pyrolysis process of municipal sludge. The activation energy E of corn stalks and municipal sludge under different heating rates showed that increasing the heating rate increased the activation energy of the low temperature section and the high temperature section to different degrees. As the proportion of municipal sludge increased from 10% to 90%, the pyrolysis activation energy decreased from 66.01~46.16kJ/mol to 44.47~17.04kJ/mol. The research provides theoretical basis and technical support for the effective utilization of corn stalks and municipal sludge.
    February 19, 2021 , DOI:
    Abstract:
    In the GPM (global precipitation measurement) era, IMERG (integrated multi satellite retrievals for GPM) with high spatiotemporal resolution (i.e., spatial resolution of 0.1° and maximum temporal resolution of 0.5 h), is one of the most mainstream satellite precipitation products. This study primarily evaluated the application ability of the latest satellite remote sensing and the retrospective IMERG Final Run precipitation product in the monitoring drought. First, the in-situ gird CPAP (China gauge-based monthly precipitation analysis product) data was selected as the reference data. Then, two dimensionless and commonly used meteorological drought indices, i.e., the SPI (standardized precipitation index) and SPEI (standardized precipitation evapotranspiration index) were calculated based on the IMERG and CPAP data at conventional scale, respectively. On the basis of the two points above, we verified the potential performance of IMERG product for the drought monitoring application over mainland China in the period of 2000-2017. The research results showed that: 1) the IMERG product could better capture the spatial pattern of monthly mean precipitation in mainland China (spatial correlation coefficient of 0.96 and relative bias of 0.02), and had higher consistency with respect to CPAP data in parts of mainland China. The field of region with correlation coefficient over 0.9 was occupied 73.7% of the continental area. However, there were relatively high spatial heterogeneity in the Xinjiang and Qinghai Tibet Plateau regions. 2) The two drought indices (SPI index and SPEI index) calculated based on the IMERG product featured high reliability and good consistency with respect to those of CPAP data at multiple time scales (1, 3, 6, and 12 months), and the regional mean correlation coefficient was more than 0.8 in most sub regions. But the SPEI index had better applicability than the SPI index, and they featuring best performance at the 12-month scale. 3) In southwestern China region, the IMERG product could satisfactorily reflect the variational process of drought (drought intensity and drought area) with time (temporal correlation coefficient over 0.96 for the SPEI), and finding out that it precisely captured the spatial characteristics of typical drought disasters on the specific month (March 2010) as well, especially for the SPEI index. The two drought indices were calculated based on the retrospective IMERG product possess high accuracy over mainland China, and they are suitable for drought monitoring in most regions. In addition, if the precipitation factor was considered only, the SPI index calculated based on the IMERG product could be applied to identify and evaluate meteorological drought at large scale. However, under the background of global warming, it is suggested that the SPEI index should be considered preferentially to utilize.
    February 19, 2021 , DOI:
    Abstract:
    Semantic segmentation of an image has become a key interdisciplinary application in the image processing, computer vision, pattern recognition, and artificial intelligence. In deep learning architectures, the convolutional neural network for interferometric semantic segmentation (CNN-ISS) is widely used in digital image processing and machine vision. The CNN-ISS can be utilized to effectively extract further features, such as texture and geometric features, indicating stronger transfer learning and generalization, compared with traditional image classifications of remote sensing. As such, the CNN-ISS is suitable for the interpretation of high-resolution remote sensing image, identification of complicated features, and crop mapping. In classification, large remote sensing images need to be segmented into specific tiled images, thereby to serve as the object of convolutional neural network (CNN) processing. However, an artificial image tiling can generate fragments on the edge of a tile, leading to the low classification accuracy of pixels near the edge of the tile. Here, the phenomenon was defined as the edge effect of tiled images, where the classification accuracy of pixels near the edge of the tile was lower than that of the central area. In this work, two indicators was designed, including the error rate with a distance to tile edges (ERD), and the error rate of the whole image (ERW), to quantify the edge effect of CNN-ISS processed tiled images. Meanwhile, the offset positions (i, k) were set for the starting point of the shift window to ensure that any pixel on the whole image must be in the central area of the tile generated under a certain offset setting. Then, five technical solutions were obtained to test the minimized edge effect of tiled images using the scores in multiple groups of categories. Taking the Tangshan as the segmented typical rural surface, a DeepLab V3 was selected as the core model of CNN-ISS to analyze the edge effect of the classification. The results showed that the pixel classification accuracy was positively correlated with the distance from the pixel to the edge of a tiled image. The highest error rate was 6.931 3% occurred along the edge of the tiled image, and the lowest error rate was 3.515 6% in the center of the tile, indicating the accuracy of the central area was higher than that of the edge. It showed an obvious edge effect of tiled images. In edge effect elimination scheme for the tiled images, the total classification accuracy improved significantly, where the Kappa coefficient and Mean Intersection over Union (mIoU) of the entire image increased 0.399 8%, 0.0122 and 1.965 1%, respectively. Taking the Kappa coefficient, one of the classic accuracy indices for the remote sensing image interpretation, as an example, the order of accuracy including the control group was: solution 2 (0.881 0)> solution 5 (0.878 9) > solution 3 (0.878 8) > solution 4 (0.877 7) > solution 1 (0.875 9) > the control group (0.868 8). Besides, the solutions of edge effects depended mainly on the types of features in the tiled images. The general law was that the tile edge effects of linear features and complex isomers (pit ponds, rural residential areas) were more obviously improved the accuracy, as the solutions were more significantly accurate, compared with that of the base land, or other agricultural land. Compared with the control group, the improvement order of IoU in the solution 2 was: roads (4.134 3%) > pit ponds (2.974 6%) > rivers and ditches (1.607 4%) > rural residential areas (0.647 5%) > other agricultural land (0.461 8%). Without changing the core model of CNN semantic segmentation, the elimination scheme for the edge effect of a tile can be used to effectively improve the accuracy of remote sensing image classification, especially for the linear features and complex isomers.
    February 19, 2021 , DOI:
    Abstract:
    In the situation that high-efficiency water-saving irrigation engineering technology is difficult to be applied popularly in field crops, it is a feasible way to optimize the water-saving irrigation schedule to improve the efficiency of irrigation water by integrating and applying the existing research results in water-saving irrigation. In this paper, the research is carried and the method to optimize water-saving irrigation schedule is developed in Xinzheng county, Henan province. The methodological processes are as follows: first, to estimate the water volumes the winter wheat requiring in its full and every growth periods by calculating indirectly using Penman-Monteith Formula recommended by FAO in 1998 with meteorological data. Second, to estimate the total water resource supplied in the full growth period of winter wheat including atmospheric precipitation, soil water content and available water resource for irrigation which can be calculated by using meteorological data, field moisture capacity and wilting coefficient of different types of soil texture, hydro-geological data which can be collected in turn. Third, to optimize and distribute the total supply water, which is few and can not meet the demand of the winter wheat in its full growth periods, to different growth stages of winter wheat, that is to get the by the method of calculating Jensen-model with full use of the existing water sensitivity index of winter wheat in different growth stages with the aim of maximizing the yield of winter wheat. Finally, to calculate the irrigation water quota in different growth stages of winter wheat on the basis of the calculating of the actual evapotranspiration, atmospheric precipitation and soil water content in different growth stages of winter wheat.The results show that: 1) The total water requirement in the full growth period of winter wheat is about 425 mm in Xinzheng, and the total supply water is less than which in normal and dry years in the full growth period, so it is necessary to implement deficit irrigation schedule. 2)Using Jensen-model, irrigating quota on each application in different growth stages of winter wheat cannot be calculated directly, actual evaporation in different growth stages should be calculated firstly, and which has been studied out that the allocation proportion of evaporations in seedling, over- wintering, booting, heading, and filling stages is 0.1564﹕0.0562﹕0.2334﹕0.3507﹕0.2032 in turn, that is their weight coefficient of sensitivity index in different growth stages. 3) The key irrigation periods of winter wheat in Xinzheng city are heading and filling stages. In high flow years, is filling stages, the irrigating quota in which accounts for 74~97% of the total irrigation amount; and in normal flow years and dry years, is heading stages, the irrigating quota accounts for 55%~73%. Under the three scenarios of non-irrigation, average irrigation and insufficient irrigation suggested in this study, the yield under insufficient irrigation estimated using Jensen-model is 26.8%~40.9% higher than non-irrigation or average irrigation in normal flow year, and 28.8%~55.0% higher in dry year. So, irrigation should be given up and insufficient irrigation should be carried out in field crops though the amount of water resources available for irrigation in Xinzheng City is only 640~1225 m3/hm2, which is 28.8%~55.0% of the quota given in Henan Province Local Standard-Agricultural Water.The conclusion can be given that the existing research and the basic data from counties now can meet the needs of formulating a deficit irrigation schedule, and the method proposed can be used for reference in other counties.
    January 26, 2021 , DOI:
    Abstract:
    In order to realize the real-time on-line detection of grain protein content and record the sampling geographical location information during combine combine-harvester harvest grain, an in-line detection system of grain protein content based on the principle of near-infrared spectroscopy was developed, which was mainly composed of near-infrared spectral sensor module, spiral sampling and conveying mechanism, control module, GPS/Beidou positioning module, industrial display integrator, etc. When the grain combine-harvester near-infrared spectral protein content in-line detection system was working, when the grain discharged by the combine-harvester grain outlet was through the spiral sampling and conveying mechanism, the stepper motor of the sampling mechanism was controlled by the controller according to the detection rate requirements and intermittent grain transmission, the controller system also controls the near-infrared spectral sensor to sample the spectral when the stepper motor stops turning, and the data such as the grain near-infrared spectrum and the positioning signal of GPS/Beidou positioning module were transmitted to host computer by RS485. The control and data processing analysis software of near-infrared sensor and sampling mechanism was compiled, and the grain protein, sampling location information, etc. were displayed and saved in real time after the grain protein prediction model. In order to verify the performance of grain protein content prediction model and online detection system, indoor calibration and field system dynamic testing were carried out, and the decision coefficient of wheat protein content prediction model was 0.865, the absolute error range was -0.96 to 1.22, and the relative error range was -7.30% to 9.53%, the root mean square error of prediction(RMSEP) was 0.638, the decision coefficient of the rice protein content prediction model was 0.853, the absolute error range was -0.60 to 1.00, the relative error range was -8.47% to 9.71%, and the RMSEP was 0.516. The results of the system dynamic field test shows that the maximum relative error of wheat protein content was -6.69%, the maximum error of rice protein content was -8.02%, the system was not significantly affected by sampling and analysis interval, and the system stability and detection accuracy meet the need of grain protein online detection in the field, which provides a scientific basis for precision agricultural operation.
    January 26, 2021 , DOI:
    Abstract:
    The aim of this study was toevaluate the effect of fermentation conditions on the cumulative esterase activity of Oenococcus oeni(O.oeni) autochthonous strains in Hexi Corridor region, and influences in the aromaticesters of Chardonnay dry white wine during the malolactic fermentation(MLF). Two O.oeni autochthonousstrains GF-2, ZX-1 were identified and preserved by Gansu Key LabViticulture and Enology and one commercial strain VP41 were used to test strains. The esterase activity of different carbon chain length substrates (C2, C4, C6) were detected in the simulated wine during MLF process.To analyze and compare the effects and characteristics of different fermentation conditions (initial pH value, ethanol concentration, SO2addition and fermentation temperature) on the production of esterase by the O.oenistrains. The modification effect of the tested strains on the aroma quality of Chardonnay dry white wine was studied by microvinification experiment. The esterase activities of O.oeni autochthonousstrains were significantly higher than that of commercial strainVP41under different pH values, and the maximum esterase activity of ZX-1 was about 63.42% higher than that of VP41. When the concentration of ethanol was 8%, all the tested strains produced the maximum esterase activity, and theO.oeni autochthonous strain hadstronger esterase producing ability. Underthedifferent SO2additions, the cumulative esterase activities of two O.oeni autochthonous strains were significantly higher than that of VP41 (P<0.05), and the esterase activity of GF-2 was significantly higher than that of strain VP41 at 18 ℃ and 22 ℃ (P<0.05) .Results of compound fermentation showed that the total esterase activity originatedfrom ZX-1 was the highest, followed by GF-2and VP41.Although the major and secondary factors affecting the esterase activity of each strain were different, the optimum conditions for esterase production of all tested strains were ethanol concentration 12%, pH 3.6, SO2addition 30 mg/L and fermentation temperature 22 ℃. The highest esterase activity of ZX-1 was 620.973 mU/mL,which indicatedthat ZX-1 had strong adaptability towine habitat.The analysis of microvinification of chardonnay dry white wine showed that six esters (amyl acetate, heptyl acetate, ethyl 3-hydroxybutyrate, ethyl myristate, ethyl trans-2-hexenoate and ethyl trans-4-decenoate) were identifiedin the wine samples after MLF, and two aromaticesters (isoamyl lactate and octylformate) were onlydetected in the wine samples fermented by O.oeni autochthonous strains. Compared with commercial strain VP41, thewines fermented by autochthonousstrains GF-2 and ZX-1 have rich variety aroma and good fragrancepersistence. Both O.oeni autochthonous and commercial strains can successfully complete MLF, especially ZX-1 has strong esterase production capability and is significantly affected by fermentation conditions, which can effectively improve the content of fruit and floral aroma compoundsin Chardonnay dry white wine, significantly enhance the regional microbial terroir characteristics of wines. The O.oeni autochthonous strain ZX-1 is more suitable to be used as MLF starter of dry white wine in Hexi Corridor of Gansu Province.
    January 20, 2021 , DOI:
    Abstract:
    Soil erosion modulus from laboratory modeling is often used to predict soil and water loss for a specific area in the field. Therefore, this study aims to investigate the erosion difference between laboratory and field simulation under various intensities of rainfall and areas on a loessal slope in western Shanxi, China. An emphasis was placed on the laboratory modeling and in-situ simulated rainfall events in the field. A systematic analysis was made on runoff modulus, erosion modulus, sediment discharge of unit width and rill development between laboratory and field. The intensities of simulated rainfall were set as 50, 60, 70, 80, 90, 100, 110, 120 mm/h, combined with natural rainfall events in the study region. A coefficient of uniformity above 85% was, considered in the simulated rainfall, similar to the raindrop distribution and size in the natural rainfall. Calibration of rainfall intensities was conducted at the beginning of each experiment. In the field, the runoff/erosion catchment plots were established in the size of 2, 3, 4, 5 m (length) and 2 m (width) in Wangjiagou small watershed in western Shanxi, while in the laboratory, that in the size of 2, 3, 4, 5 m (length) and 0.5 m (width) in the Taiyuan University of Technology. The soil surface was bare, where the soil type was loessal, and the slope gradient was 20°. Initial water content of soil was determined all the same in simulated experiments. Each rainfall event was repeated two times. The period from the rainfall beginning to runoff occurrence was recorded as “runoff occurrence time” during each rainfall event, where the duration of each rainfall simulation was 30 min from the appearance of runoff. All samples of runoff and sediment were collected in the polyethylene bottles with the volume of 1 L at the bottom end of the plot at 2 min intervals, as the final runoff volume and sediment yield. The erosion modulus and runoff modulus were analyzed with the rainfall intensity and area, in the field and laboratory, indicating significant correlation between rainfall intensity (slope length) and sediment yield. Rill morphology and sediment discharge of unit width were further measured to explore difference between field and laboratory. The results showed that laboratory measurements were greater than those of field in-situ simulation. When the slope area of field was 4 times that of the laboratory, the runoff and sediment yield were not 4 times, where the larger the area was, the smaller the ratio of erosion was, indicating that the amount of soil erosion in the field cannot be predicted simply by the laboratory measurements. The rainfall intensity had also greater impact on the runoff erosion than the area. Under the same rainfall condition, the rill was more likely to occur on the laboratory slope surface, and more developed than on the field, which was more inclined to cut rill deep to enhance the runoff erosion force of laboratory slope. Under certain rainfall intensity and slope length conditions, the mass flux tended to be stable after the first peak at the 10~14 min in the field, while the peak appeared at 4 min in the laboratory, where the value was 1.58~10.40 times of that in the field. It showed that the sediment discharge of unit width and its fluctuation in laboratory were higher than that in the field, and the response time was shorter.
    December 16, 2020 , DOI:
    Abstract:
    Using hydraulic structures (especially gates) to measure flow is currently the most widely used method for water measurement in irrigation districts of China. The main advantages of this method are lower investment and being able to control while measuring. However, its accuracy for field applications is very limited while use traditional way, in some cased the maximum error may reach 30%. So, improving the accuracy of the water measurement with gates is an urgent matter for irrigation water management. Lots of effort has been made in recent years on flow rate measurement under sluice gate, and various flow rating models were presented in literature. However, these methods almost focus only on one certain flow condition and mostly does not specially concern the application of field calibration. In addition, the empirical coefficients (as flow coefficient and submergence coefficient) of those formulas have remarkable uncertainty, and most semi-empirical formulas were based on theoretical derivation and laboratory experiments which are quite different from the actual field application. All of those made it hard to get precise measurement of flow in the field. The main goal of this paper is to propose a flow calculation model with simple form and can be applied to multiple gate flow regimes. This paper established a 3D hydrodynamic model of the actual sluice gate to study the hydraulic characteristics of the sluice under different flow conditions and verified that the selected grid size has no influence on the results, and then combined 3D numerical simulation, indoor model experiment verification with field prototype observation data to propose a flow calculation model applied to multiple flow regimes. The research method of this paper is first verified the validity and accuracy of the calibration model based on the measured data proposed. Then analyzed the calibration effect of the model applied to the gate in different flow modes, and check whether it can be used for free and submerged orifice flow. Furthermore, validate the field data of the proposed model method and analyze the source of error. This paper used one portion of the field data to calibration the model, and used another portion to verify the accuracy of the model. Finally, this paper analyzed the accuracy of the model based on an example of a gate in the middle route of South-to-North Water Transfer project. This paper used measured data in September were used for calibration, and then the data in August, October and November were used for verification. Results show that 1. The model can be used to determine the flow rate with relatively high accuracy, and 90.63% of the data has less than 5% error; 2. The model can be sued for both free and submerged orifice flow rate and the proportion within 5% error dropped to 86.67%. Using a gate of the South-to-North Water Diversion Middle Line in August, October, and November, the accuracy of the model can be verified to achieve 77.64% of the data error within 5%, and 95% of the data error within 10%; The proposed model is simple, smooth and continuous. In field application, it is promising for improving the accuracy of gate flow measurement with more rating data.
    November 04, 2020 , DOI:
    Abstract:
    The use of recycled manure solids (RMS) as dairy bedding material has become a promising technology with the merits of sustainable manure management and cost saving for purchasing traditional bedding. However, cow dung contains certain amounts of pathogenic bacteria, thus the use of RMS would increase the risk of direct contact of pathogens with cows’ udder. Such serious problem has undermined the use of RMS as dairy bedding material. Drum fermentation for the bedding production has many advantages (i.e. high temperature, short time), thereby it is getting more and more attention. The objective of this study was to investigate the stability and biological safety of RMS production process using drum fermentation in different seasons, and to clarify the factors affecting the growth of pathogenic bacteria in the dairy cows’mastitis. The drum-type RMS producing system employed was composed of a two-stage solid-liquid separator, a horizontal-rotation drum fermentation tank, as well as feeding and discharging components. The automatic control system monitored equipment operation and temperature changes in real time. The drum temperature was obtained by the temperature sensors installed on the inner wall of the drum including inlet, center, and outlet. Samplings were performed from the inlet, 1/3, 2/3, and outlet of the drum. The plate culture method was used to detect the main mastitis pathogenic bacteria (i.e., Eschrichia coli, Staphylococcus aureus, Streptococcus, and Klebsiella) at different positions within the drum during the summer and winter. At the same time, the physical and chemical properties (water content, pH, total carbon, total nitrogen, ash, particle size distribution, roller temperature) of RMS were also tested. Additionally, the main factors affecting the growth of mastitis pathogens was investigated via Pearson correlation analysis.The results indicated that the fermentation temperature during the production process was stable and maintained above 65 oC both in summer and winter, and the final moisture content at the drum outlet was less than 45%. In both seasons, the particle size distribution at different positions of the roller was mainly concentrated at 0.5 mm to 2.0 mm. With the fermentation process, the large particle size gradually converted to small and medium particle size. The number of mastitis pathogens in summer and winter was highest at the drum inlet, and gradually decreased at higher fermentation temperature. At 1/3 of the drum, the number of major mastitis pathogens was significantly reduced. Streptococcus. and Klebsiella. were not detected at the drum outlet in both seasons. However, the number of Eschrichia coli and Staphylococcus aureus at the outlet of the drum in summer was about 3 lgcfu/g higher than that in winter. It may be related to the moisture content of the cow dung at the inlet of the drum. Therefore, the moisture content of the inlet of the drum should be strictly controlled between 50% and 65%. Using the Pearson correlation analysis, it was found that the major factor affecting main mastitis pathogen was drum temperature, followed by total carbon. From the security point of view, RMS should be used immediately after production to avoid environmental impacts. The results found in this study can provide deep insight for the application of drum fermentation technology to produce safer RMS.
    October 21, 2020 , DOI:
    Abstract:
    To promote the development, automation, and standardization of Chinese cuisine, it is necessary to carry out a systematic and in-depth study so as to obtain the inherent principles of heat transfer and the corresponding quality changes during the cooking process. Chinese stir-frying is one of the most distinctive and widely used cooking method, and numerical simulation is the only way to study the heat transfer process of food particles during the Chinese stir-frying. In order to study the mechanism of heat and mass transfer and the changes of maturity and quality of food particles during the Chinese cuisine process, a heat and mass transfer model including multiphase coupling phase transition and shrinkage was developed to simulate the Chinese stir-frying process of food hygroscopic porous medium based on the porous media theory, Fourier's law, Newton's cooling law, and Darcy's law. The non-equilibrium evaporation formulation, shrinkage formulation, energy, momentum and mass conservations of water, and gas governing equations were considered in this model and it was finally solved using finite element method. The temperature history, moisture content, and volumetric shrinkage rate of the Chinese stir-fried pork loin were used as comparations to validate the model accuracy. The results indicated that the accuracy and robust properties of this model was greatly increased after considering the shrinking process. To reveal the mechanisms of heat and mass transfer inside food particle, water evaporation rate of particle surface, volumetric shrinkage rate, pressure variations, moisture content and temperature distributions were all simulated for Chinese stir-frying process. The simulation results showed that the water loss, which was induced by strong convection heat transfer, was the main reason for shrinkage. The moisture loss rate and volumetric shrinkage rate were increased by the surface evaporation rate, and the particle internal pressure was affected by volumetric shrinkage.Since the volumetric shrinkage rate was similar to water loss rate, the moisture content and shrinkage were associated as an important indicator for evaluating cooking quality of food particles. Additionally, the heat transfer efficiency of particles was greatly enhanced by shrinkage because of the increasing surface area to volume ratio. The shrinkage could be used to improve the overall moisture content of food particles if evaluated from the perspective of cooking quality optimization. Combined with the maturity value theory, the effect of controlling methods of “Huohou” on the maturity and quality of food particle were further explored in this study. The simulation results indicated that the increase of the efficiency of heat and mass transfer and internal heating rate, and the decrease of average moisture content were mainly affected by the finer cutting technique of food particles, the higher preheat oil temperature, and the more vigorous stirring operations. The food particles could reach its maturity values before the average moisture content rapidly decreased under the appropriate “Huohou” controlling. Thus, the average time of food particles reaching cooking maturity termination was significantly decreased. “Huohou” controlling exhibited a significant (P <0.01) effect on the cooking quality and could bring significant advantages for obtaining food particles with better cooking quality.
    October 09, 2020 , DOI:
    Abstract:
    In the global scope, the application of vegetable grafting seedling technology is very extensive, and the seedling enterprises completely rely on professional grafting technical workers, which leads to the aging of employees and the shortage of employment and other problems. Grafting machine can effectively overcome the shortcomings of low efficiency of manual grafting, improve the quality of grafting seedlings and standardized operation. For the existing grafting machines, most of them need artificial feeding seedling, and the production efficiency of machines is greatly limited, which affects the popularization and application of grafting machines. In order to solve the problems of rootstock cotyledon damage and petiole splitting in the process of artificial feeding seedling of grafting machine, a rootstock seedling positioning mechanism was designed based on the principles of positive pressure air pressing seedling and negative pressure adsorption positioning. Firstly, the external geometric parameters of cucurbita moschata seedlings and the breakpoint pressure of cotyledon were measured to provide basis for the design of adsorption block structure and working parameters. Then, the trajectory equation of cotyledon back development curve is extracted by point fitting method, which is used for the profile design of adsorption block working face. By establishing the finite element analysis model of the mechanism, under the given boundary constraint conditions, the dynamic simulation of the airflow field inside the adsorption block is carried out by using CFD software, so as to obtain the distribution of the flow field in the gas chamber and the influence of various factors on the adsorption force of rootstock cotyledon. The optimal structural parameters of the adsorbent block were determined by simulation orthogonal test. The order of the influence of various factors on the average suction is outlet negative pressure > diameter > depth. When the negative pressure at the outlet of adsorption block is 3 kPa, the pore diameter is 1 mm and the depth of suction hole is 4 mm, the pressure of 21 suction holes is less than the rupture point pressure of cucurbita moschata cotyledon, and the adsorption block has good adsorption and localization ability for cotyledon. According to the results of feeding seedling test, the adsorption success rate of cucurbita moschata cotyledon was 96.67%, the success rate of pressing seedling was 99.33%, the comprehensive feeding success rate of seedling was 96.03%, and the seedling injury rate was only 0.67%. The operation performance of the mechanism could meet the requirements of automatic feeding seedling of grafting machine. The reasons for the failure of cotyledon adsorption were the inaccurate control of cotyledon direction and feeding seedling height, and the petiole splitting caused by too small cotyledon angle. The simulation test of adsorption block working face profile and structural parameters is of great significance to improve the flexibility and safety of rootstock. It can greatly shorten the design cycle of adsorption block. The research results provide theoretical basis and design reference for solving the problem of automatic feeding seedling of grafting machine.
    October 09, 2020 , DOI:
    Abstract:
    In the high temperature season, the surface temperature of the soil is very high, and the internal water content of the soil is rare. Sudden rainfall has a great influence on the dynamic change of soil temperature and the water-heat exchange and migration. At present, there are few research achievements on the hydrothermal interaction of soil in the process of rainfall unsaturated infiltration, which cannot truly reveal the influence mechanism of rainfall unsaturated infiltration on soil temperature change and heat transfer. Therefore, it is very important to study the influence of the water movement caused by rainfall infiltration on the soil temperature change and the law of heat transfer. In order to reveal the soil moisture movement in unsaturated rainfall infiltration process of high temperature and the influence of soil heat transport mechanism, this paper established an soil heat transport in the process of rainfall infiltration mathematical model and finite element numerical calculation program is compiled, in view of the typical silty soil layers in nanjing, was carried out by unsaturated rainfall infiltration to the influence of soil heat transport, numerical calculation and analysis. The results showed that in the absence of rainfall, soil temperature change and heat transfer were mainly caused by heat exchange between the surface soil and the environment, and the depth of heat transfer was about 0.2m. Under the effect of constant rainfall intensity, the soil matric suction and volumetric water content in the silt layer change gradually with the duration of rainfall due to the unsaturated infiltration process of rainfall. When the soil moisture front reaches different depths, the volumetric water content increases rapidly, and the soil volumetric water content after the moist front gradually approaches the saturated volume water content. Under the influence of rainfall unsaturated infiltration, heat exchange occurs between low-temperature rainfall in soil pores and soil particles, which changes the distribution law of the original soil temperature field. Moreover, with the continuous increase of rainfall infiltration depth, the influence of rainfall infiltration process on soil heat transfer gradually weakens. By comparing and analyzing the field monitoring data and numerical calculation results, the change rules of soil rainfall infiltration and heat transfer were revealed, and the rationality of the numerical calculation program of soil heat transfer was verified. The research results can provide important reference for agricultural water conservancy engineering and soil and water conservation, distribution and utilization of soil hydrology and water resources, urban water resources control and ecological environment protection.
    September 15, 2020 , DOI:
    Abstract:
    Technology of straw bale combustion is one of the effective ways to realize the clean utilization of agricultural residue, which has aroused widespread concern. In this paper, the latest research progress of straw bale combustion was reviewed, the reaction principle and combustion characteristics of straw bale combustion were described, the generation and emission of particulate matter in the process of straw bale combustion were analyzed, such as NOx, CO and particle. And the research progress of straw bale combustion types, principles and characteristics were systematically summarized. According to the technical characteristics and heating scale, we divided straw bale combustion into two types, one was continuous bale combustion, which can realize continuous feeding and ash cleaning in the combustion process, maintain a stable combustion state in the combustion chamber, and was suitable for the central heating area with large heating area, that mainly included cigar-bale combustion and reciprocating grate combustion. The other was sequential batch combustion technology, which had advantages in small floor area, simple and convenient operation, usually used for small heating mechanism, and it included forward combustion technology and reverse combustion technology. Based on the global literature search, the research hotspot, institutions and development trend of straw bale combustion were analyzed. The running cost of straw baled heating was evaluated. It was found that the straw bale combustion has the characteristics of simple heating process and low operation cost. The operation cost was 19.8 yuan/m2, which was suitable for the industrialization promotion of clean heating in villages and towns. Straw bale combustion technology had gradually attracted the attention of scientific researchers. Developed countries in Europe had made some progress in the field of straw bale combustion, such as combustion mechanism, boiler structure, reduction of flue gas emission, etc. And at present, the research of combustion technology had focused on flue gas emission reduction and environmental impact assessment. The existing straw bale combustion technology still has some problems, such as insufficient combustion, unclear generation mechanism of flue gas pollutants, higher NOx and particle emission. It was suggested that we should pay more attention on research of pollutant emission characteristics, and it is encouraged to reduce the generation of flue gas pollutants from the source.
    September 14, 2020 , DOI:
    Abstract:
    Biocrusts are fundamental components and surface landscape in arid regions, while affect biogeochemical processes. Actually, biocrusts stoichiometry is largely unknown in the desertified region of Northern China. Especially, how precipitation influences biocrusts stoichiometry in desert steppe is still uncertain. A manipulative experiment with additions of precipitation and drought treatment by using rain shelters and sprinkler irrigation system to control precipitation input, which was conducted to test their effects on the biocrusts in desert steppe with contrasting natural precipitation. Then the carbon (C), nitrogen (N) and phosphorus (P) contents of biocrusts were measured to explore the C: N: P stoichiometry and its driving factors. After one-year precipitation control experiments, we found that drought treatment increased C: N, C: P, and N: P ratios in the crust layer, and the ratios in the underlying soil increased after increasing precipitation. Second, drought treatment increased the difference in C between the crust layer and the underlying surface, while reducing the difference of the N and P content. Increase precipitation exacerbates the difference in N and P content between the crust and the underlying surface. But drought treatment was conducive to the accumulation of C in the crust layer. The effectiveness of soil P in the crust was reduced after Increase precipitation. Changes in C: N: P stoichiometry may be caused by changes in soil properties, especially C and soil water content (SW). Of course, soil microbial biomass carbon (SMBC) and nitrogen (SMBN) were also important in shaping C: N: P stoichiometry. Overall, these results demonstrated that the C: N: P stoichiometry of the crust layer and the underlying surface has different responses to precipitation in the desertified region of Northern China.
    August 25, 2020 , DOI:
    Abstract:
    Territorial spatial planning is the important measure of regional resources utilization and ecological protection, promote modernization of space governance system, service for ecological civilization construction and national modernization strategy, the territorial ecological restoration is the activities and processes of territorial space comprehensive improvement and ecological restoration, to direct at imbalance of regional spatial pattern, and inefficiency of resource utilization, and the damaged of the ecological function. It is the main content of establishment and implementation of the territorial spatial planning. Ecological restoration partition is the important premise of reasonable formulation of territorial spatial ecological restoration planning and scientific and efficient to carry out ecological restoration. Since the 1950s, in the regional-dominated functional zoning, China has carried out such regionalization work as agricultural regionalization, economic regionalization, land use regionalization, urban function regionalization, ecological function regionalization and land main function regionalization. The functional zoning of territorial space with different emphasis has different methods and basis, such as factors and indicators of evaluation, space types of zoning and grading of zoning due to the different goals and functional positioning of zoning. New era, the territorial spatial ecological restoration have been given a new responsibility and mission. It is the urgent needs and important guarantees to accelerate territorial spatial ecological restoration, and promote territorial spatial bearing capacity, and construction the pattern of ecological security in territorial space, and it has important theoretical and realistic significance to promote the harmonious coexistence between man and nature, and promoting the construction of ecological civilization and beautiful China. Through the analysis the zoning positioning and connotation characteristics of regional land, ecology, economy and other dominant functions, based on the basic theory of "life community", "Production - life - ecology" coordination and "Suitability management",and other theory about territorial spatial planning and ecological civilization construction, and based on the combination of "top-down" and "bottom-up", the idea and method of ecological restoration zoning of territorial space was proposed based on dominant functional zoning: First, to understand the background of natural resources, and finish the first level ecological function foundation partition; Second, to evaluate the status of regional ecological functions, and complete the secondary ecological restoration pattern zoning; Third, to define key areas of ecological restoration, and complete three-level ecological restoration mode zoning. This method takes the rule of territorial differentiation, dominant ecological functions and major ecological problems as the basis for zoning, and integrates ecological, economic, social and other factors. The partitioning method has the following characteristics: First, it highlights the dominant function; Second, follow the ecological law; Third, adaptation of the spatial scale; Fourth, strengthen up and down connection. In the design of this method, the goal orientation, function orientation, problem orientation, task orientation and other aspects are comprehensively considered, so as to obtain scientific and feasible zoning results as far as possible, which is conducive to the ecological restoration and comprehensive improvement of territorial space. However, it still needs to improve constantly in practice, to analyze the development trend of ecological restoration zoning: First, it is to emphasize differences; Second, to emphasize simplicity; Third, to emphasis on operability; Fourth, to emphasis on evaluation. The research is of positive significance to the compilation, implementation and ecological control of territorial space ecological restoration planning, and can provide scientific and technological support for the overall protection, systematic restoration, comprehensive improvement and to promote the development of a beautiful China.
    August 25, 2020 , DOI:
    Abstract:
    Efficient nutrient utilization is an important part of agriculture green development. As a typical representative of agricultural mechanization and modern production, Heilongjiang Land Reclamation Area (HLRA) was one of China's major grain-producing regions and had produced 410 million tons of grain since 1949. And the total grain output in 2018 was 2.296 million tons, accounting for 3.47% of the total national output. So evaluation and analysis of the nutrient balance of farmland soil during the period were critical. And HLRA was chosen as the research object in this paper. The nutrient balance method was developed to analyze and evaluate the input and output of N, P, and K of farmland soil from 2000 to 2018. The results showed: From 2000 to 2018, N, P, and K input of farmland soil in HLRA showed a steady-growth-decline trend. The N, P and K input in 2000 was only 4.41×108 kg, 6.79×107 kg and 2.09×108 kg. The nutrient input of farmland soil increased rapidly from 2003 to 2012, and the highest value was 8.43×108 kg, 1.35×108 kg and 5.61×108 kg. The N, P and K input in 2018 was 6.56×108 kg, 1.27×108 kg and 5.29×108 kg. The main ways of N input were chemical fertilizer, organic fertilizer and biological nitrogen fixation; the main ways of P input and K input are chemical fertilizer and straw returning to field respectively. From 2000 to 2018, N, P, and K output of farmland soil in HLRA showed a steady-growth-decline trend. The N, P and K output in 2000 was only 3.16×108 kg, 3.23×107 kg and 2.06×108 kg. The nutrient output of farmland soil increased rapidly from 2003 to 2012, and the highest value was 6.64×108 kg, 7.62×107 kg and 5.06×108 kg. The N, P and K input in 2018 was 6.12×108 kg, 7.34×107 kg and 4.88×108 kg. The main ways of N output and P output were grain and straw; the main way of K output was straw. Also, the N output from ammonia volatilization should be paid attention to. N, P, and K input per area of farmland soil in HLRA showed a steady-growth-steady trend from 2000 to 2018. The N, P, and K input per area in 2000 was 228.80 kg/hm2, 35.23 kg/hm2 and 108.46 kg/hm2. The value in 2018 was 228.08 kg/hm2, 44.32 kg/hm2 and 183.98 kg/hm2. N, P, and K input per value of farmland soil in HLRA showed a decline trend from 2000 to 2018. The N, P, and K input per value in 2000 was 0.03621 kg/yuan, 0.00558 kg/yuan and 0.01717 kg/yuan. The value in 2018 was 0.00949 kg/yuan, 0.00184 kg/yuan and 0.00765 kg/yuan. N and P utilization efficiency of farmland soil in HLRA showed a growth trend from 2000 to 2018, but K showed a decline trend. The N, P and K utilization efficiency was 51.03%, 27.98% and 10.04% in 2018.N profit and loss of farmland soil in HLRA showed a growth trend, P profit and loss of farmland soil in HLRA showed a steady trend, and K profit and loss of farmland soil in HLRA showed a decline trend. Compared with Australia, Canada, France, Germany, Japan, UK, and the USA, N profit and loss in 2018 was 15.08 kg/hm2, which was at an excellent level. But P profit and loss in 2018 was 18.78 kg/hm2, which was at a poor level. And K profit and loss in 2018 was 14.16 kg/hm2. N and K were in a nutrient balance state, but P was in a nutrient surplus state, which was related to the fact that P input to the farmland was easily fixed by soil. At the current stage, the fertilizer input in HLRA was mainly relying on chemical fertilizer, and the amount of organic fertilizer was relatively low, which was not conducive to fertilizing soil and slowing down the trend of black soil degradation. So HLRA was suggested to develop various methods, such as subsidies and demonstration, to gradually promote the application of organic fertilizers. Besides, Long-term monitoring of nutrient balance of farmland soil was required in the future, which was beneficial to scientific adjustment and optimization of soil nutrient management measures and strategies, improving nutrient utilization efficiency, guaranteeing food security and boosting agriculture green development.
    August 25, 2020 , DOI:
    Abstract:
    Water vapor movement is one of the important components of total water flux in the vadose zone of drylands. Generally, though the amount of these non-rainfall water is usually quite small in comparison to rainfall, the vapor sorption and condensation are vital water sources for plants, insects, and small animals when soil water content is very low. In arid and semiarid drylands, biocrusts have been regarded as a critical upper layer which greatly changes surface soil water movement and even surface soil energy balance, however, their influences on water vapor sorption and condensation have not yet been fully understood. Therefore, it is necessary to investigate the characteristics of water vapor sorption and condensation in biocrusts and their influential factors for quantifying vapor water supplement from biocrusts and better-understanding biocrust effects on vapor movement in drylands. Due to this reason, we investigated the characteristics of vapor sorption and condensation in typical cyanobacteria crusts (cyano-crusts), cyanobacteria and moss mixed crusts (mixed crusts), moss crusts (more than 30 a), and bare sand (aeolian sand) on the Chinese Loess Plateau. In this study, through analyzing the vapor sorption (adsorption and desorption directions) of biocrusts and bare sand in laboratory and measuring their vapor condensation (condensation process and daily vapor condensation amount) in field. Our results showed that the soil water content increased with the water activity (aw), and the biocrusts significantly increased vapor sorption amount as compared with bare sand. Specifically, the water vapor adsorption of biocrusts was averagely 66.7% higher than that of bare sand. Especially for moss crusts, which was 1.0-2.2 times higher than that of bare sand. Furthermore, the water vapor sorption amount was also varied between different types of biocrusts, and the water vapor adsorption of cyano-crusts, mixed crusts, and moss crusts were obviously different, which was 0.011, 0.020, and 0.015 g/g, respectively. The simulation results implied that the GAB (Guggenheim-Anderson-de Boer) model was capable of descripting vapor sorption isotherms of biocrusts, with R2>0.99, RMSE<0.001 2 g/g, and E (mean relative percentage deviation modulus) <16.0%. We also observed significant hysteresis effects according to the hysteresis index in WSIs, in decreasing order of moss crusts, mixed crusts, cyano-crusts, and bare soil. The hysteresis index of biocrusts was 2.0-3.0 times than that of the bare sand. Moreover, the results of vapor condensation showed that the water vapor mostly condensed from sunset to sunrise for all the treatments in our study, then it gradually evaporated and reached the minimum value at ~15:00. In comparison to the bare sand, the rates of water vapor condensation and evaporation in the biocrusts were much faster. Especially in September, the vapor condensation amount of biocrusts was averagely 1.5 times higher than that in the bare sand. Overall, the vapor condensation was deeply influenced by the meteorological factors (i.e. air temperature and relative humidity). Furthermore, as compared with bare sand, the daily condensation amount of the biocrusts was averagely 1.6-1.8 times higher than that of bare sand. Particularly, the condensation amount of different types of biocrusts was varied, and the condensation amount of moss crusts the highest and was still 81.8%, 11.1%, and 5.3% higher than that of the bare sand, cyano-crusts, and mixed crusts, respectively. In conclusion, vapor sorption and condensation of biocrusts played an important role in soil vapor movement, because i) biocrusts covered soil surface and enhanced vapor sorption amount due to the high clay and organic matter contents, and ii) biocrusts increased vapor condensation amount by improved soil properties and moss mulching effects. Therefore, biocrusts should be intensively considered in water transport studies in drylands.
    August 07, 2020 , DOI:
    Abstract:
    Since 2000s, the agricultural structure of Sanjiang Plain had been greatly adjusted with large amount of dry land crops changed into rice, which resulted in a set of problems in the utilization of water resources. Based on the background above, it was necessary to study the main crops’ water profit and loss situation, so as to put forward regional irrigation strategies and serve the national food security. To reveal the water surplus & deficit situation of the middle crop、spring wheat and spring wheat in Naoli River Basin, which was located in the hinterland of Sanjiang Plain, the Priestley Taylor formula and Crop Water Surplus & Deficit Index were used in this article. The MODIS image data, the long-term sequenced meteorological data and the DEM data were used as its fundamental data resources in all the above analysis. Results showed that the Potential Evapotranspiration (ET0) increased from 910.25 mm in 2000 to 964.04 mm in 2015 in this river basin. The water demand of main crops, including middle crop, spring wheat and spring maize, were also increased at different ranges as a whole; The natural precipitations could not meet the middle rice’ irrigation demand, which was characterized by Crop Water Surplus & Deficit Index decreasing trends from 2000 to 2015 in Naoli River Basin, and its absolute value was increasing from northeast to southwest in the spatial distribution. The spring wheat’s Crop Water Surplus & Deficit Index was larger than the middle rice, and it showed similar characteristics in the whole spatial distribution for each years. The spring maize’s Crop Water Surplus & Deficit Index showed this spatial characteristics of northwest slightly lower than that in the southeast, which was both in mild water shortage status in Naoli River Basin; Drought classification was evaluated on the basis of Crop Water Surplus & Deficit Index, so as to study on the drought characteristics in Naoli River Basin. Results showed that the middle crop, which area proportion growth rate reached 143.46%, was basically in mild drought state in this basin. Despite at the state of water shortage, spring wheat had not reached the drought standard as a whole. The spring maize area in mild drought state in Naoli River Basin had decreased by 79.90%. Agricultural structure of this basin had been greatly adjusted with large amount of spring wheat and spring maize changed into middle rice, which resulted in a rapid increasing for the middle rice since 2000, and this phenomenon led to water shortage severely. It was remarkable that the spring wheat and spring maize owned extremely rare negative impact on the water surplus and deficit situation in this basin. These research results provide the references and consultancies for the farmland irrigation schemes and agricultural structure adjustment in Naoli River Basin.
    August 07, 2020 , DOI:
    Abstract:
    The remote sensing images used in agricultural production are often affected by clouds during the acquisition process. As a result, the sharpness of the acquired image will be reduced low sharpness of the acquired image. The interpretation of terrain information in such unclear remote sensing images can be very difficult and the subsequent applications will be greatly affected, such as crop growth detection, crop classification and yield prediction. In order to solve this problem, a method for cloud removal of remote sensing images based on improved conditional generative adversarial net-work was proposed in this paper. This method provides a common network architecture for the removal of thin and thick clouds in remote sensing images. In addition, the generator of network is improved to solve the problem of image generation caused by the single feature extraction method of the network. Firstly, use a series of convolutions to extract the feature information of the input image. Then, multi-scale feature maps are obtained from the feature information through the spatial pyramid pooling operation. Finally, restore these different size feature maps to the original size and mix them together. In this way, the scale of the feature extraction by the generator can be increased. The resulting effect will also increase accordingly. In order to evaluate the cloud removal method, experiments were performed using remote sensing image data sets and the results of this method were compared with traditional conditional generative adversarial net-work method and the pix2pix method. At the same time, two objective indicators were introduced for evaluation. They are the peak signal-to-noise ratio (PSNR) and the structural similarity(SSIM). The experimental results show that 1)The method can The optical remote sensing images used in agricultural production are often affected by clouds during the acquisition process. As a result, the sharpness of the acquired image will be reduced. Decreased image clarity will make it difficult to interpret feature information. Subsequent applications in agricultural production will also be affected, such as crop growth detection, crop classification and yield prediction. In order to solve this problem, a method for cloud removal based on improved conditional generative adversarial net-work was proposed. This method generates the mapping relationship between pixels of the cloud and cloudless data through training conditional generative adversarial net-work. And it complete the transformation from cloud remote sensing image to cloudless remote sensing image on this basis. Eventually, it can effectively realize the removal of the cloud component in the optical remote sensing images. And at the same time, it can realize the restoration of details of optical remote sensing images. In this way, it provides a common network architecture for the removal of thin and thick clouds in optical remote sensing images. However, the single feature extraction of the conditional generative adversarial net-work leads to poor quality of the generated results. Therefore, the generator of network is improved to solve the problem. Firstly, a series of convolutions are used to extract the feature information of the input image. Then, multi-scale feature maps are obtained from the feature information through the spatial pyramid pooling operation. Finally, these different size feature maps are restored to the original size and are mixed together to generate the final cloudless optical remote sensing images. By this means, the scale of the feature extraction by the generator can be increased. The resulting effect will also increase accordingly. In order to evaluate the cloud removal method, experiments were performed using optical remote sensing image data sets. In the experiments, the results of the improved method were compared with three types of methods. They are original CGAN method, traditional cloud removal method and the pix2pix method in deep learning. For better evaluation, two objective indicators were introduced to make a quantitative assessment of experimental results. They are the peak signal-to-noise ratio (PSNR) and the structural similarity (SSIM). The experimental results show that1) The method can be applied to the cloud removal of thin cloud and thick cloud in optical remote sensing images. And it achieved good results in both types of cloud removal; 2) Compared with the original CGAN, the generated cloudless remote sensing image is closer to the real cloudless remote sensing image. Remove the thin cloud using the improved model, the PSNR value increased by 1.64db. And the SSIM value increased by 0.03. Remove the thin cloud using the improved model, the PSNR value increased by 1.05db. And the SSIM value increased by 0.04; 3) Compared with the traditional cloud removal method, improved model removes cloud layer in optical remote sensing image more thoroughly. At the same time, the color of the features in the optical remote sensing image is better and more realistic. Compared with the pix2pix method, details of the ground in the generated cloudless optical remote sensing images are better recovered. The value of the PSNR indicator for remote sensing images increased by 1.24db after the removal of the thin cloud. The value of the PSNR indicator for remote sensing images increased by 0.89 after the removal of the thick cloud. The value of the SSIM index of remote sensing images has also been increased accordingly. The results verify the feasibility of removing cloud from remote sensing images based on improved conditional generation of adversarial network. Furthermore, it can provide a new idea and method for agricultural remote sensing image processing.
    August 05, 2020 , DOI:
    Abstract:
    National policies promote the rapid development of electric vehicles, agricultural vehicles are becoming more and more electric. In general, when the battery is used as a power supply, a lot of heat will be generated. In addition to the more complex working conditions of agricultural vehicles and the compact layout of battery packs, it is inevitable to cause the thermal accumulation of batteries, resulting in the battery temperature exceeding the optimal operating temperature range and damaging the battery. At this time, an appropriate thermal management strategy is needed to control the battery temperature and make it work within a reasonable temperature range. Therefore, based on the principle of phase change heat transfer and pump-free circulation, a power battery thermal management system with cooling or heating functions is presented. Taking ternary lithium batteries as the research object, the two-way working modes of thermal management system were tested under cooling or heating conditions. Under the cooling condition,The cooling capacity of the two thermal management systems under natural convection cooling and forced convection cooling conditions was studied when the initial temperature of the battery box was 40, 50, 60 and 70 ℃. And for the thermal management system two, the influence of the inclination angle on its heat dissipation and temperature uniformity was studied. Under the heating conditions, the heating capacity of two thermal management systems was studied, and then for the thermal management system two, the initial temperature of different batteries and the heat exchange uniformity of the thermal management system two were studied. The results show that the system can realize the operation switching management of cooling and heating two-way modes based on high or low temperatures. In other words, the switch of thermal management can be realized by controlling the opening and closing of the valve at the right temperature. The test results show that, under the cooling condition, thermal management system two provides better heat transfer, It can also be interpreted as the heat dissipation capacity of the heat exchanger plate with four vertical tubes is stronger than that of the single serpentine tube, compared with natural convection, forced convection on the condenser side can increase the heat transfer power of system 1 by 10% ~ 44.2%, and system 2 by 20% ~ 48.6%; when the temperature of the battery box is 60℃, the maximum temperature difference of the heat exchange plate of the natural convection heat dissipation system is less than 2℃, and the maximum temperature difference of the heat exchange plate of the forced convection heat dissipation system is less than 1℃; at an initial battery temperature of 25°C and a discharge rate of 1C, 2C, and 3C, forced convection heat dissipation at the end of discharge can reduce the average temperature of the battery box by 2.1, 3.9, and 4.7°C, respectively. Under the heating condition, the power of the battery box in many groups of experiments is consistent. Considering the tilting effect of the heat exchanger plate in the vehicle driving, it is restricted by the flow distribution of the working fluid, and the temperature uniformity is better than the heating condition in the heat dissipation condition.
    July 22, 2020 , DOI:
    Abstract:
    A new kind of clay modified by cetyltrimethyl ammonium chloride(CTAC) was prepared to solve the problem of sand fixation in desert highway construction and maintenance. H1, H2, H3, H4, H4, H5 and H5 were assigned to the treatments of CTAC and clay with mass ratios of 2:4, 3:4, 4:4, 5:4 and 6:4, respectively. In addition, unmodified clay was prepared as the blank control group H. The water retention performance was tested in an artificial climate box to simulate the desert climate. And the changes of mass and compressive strength were tested before and after ageing to test its anti-aging property. The grass planting experiment was conducted to analysis the effect of materials on germination rates. At last, the mechanism of sand fixation and water retention was analyzed by X-ray diffractometer, infrared spectrum analyzer and scanning electron microscope. The results showed that the moisture content of the original clay decreased to 0 at the 3rd day. And the water retention property was obviously improved with the increase of CTAC content. The highest and lowest moisture content were H5 and H1, respectively. And the moisture content on the 7th day was 27% and 7%, respectively. The moisture content of H4 was also higher, 23% on the 7th day. This indicated that the water retention performances of modified clay samples were significantly improved. With the increase of CTAC content, the water retention performance was gradually enhanced. In the compressive strength test, the universal testing machine failed to measure the data due to the low strength (less than 0.1 MPa) of the unmodified clay group H. The strengths of the modified clay samples were significantly improved, and the strengths of the modified clay samples all met the standard requirements (no less than 1 MPa). Moreover, the strength of the modified clay increased with the increase of the content of CTAC, with the highest strength of H5 (2.2 MPa), the lowest strength of H1 (1.7 MPa), and the higher strength of H4 (2.1 MPa). This indicated that CTAC could bond dispersed clay particles together to form a consolidation layer, and its strength could meet the requirements of mechanical construction. In the anti-aging performance test, after aging for 500h, no obvious cracks were found on the surface of the samples, and the water retention performance decreased by less than 5%. The strength loss rate and mass loss rate of all the groups increased with aging time, and the higher the CTAC content was, the higher the strength loss rate and mass loss rate were. The strength loss rates of H4 and H5 were respectively 7.3% and 10.4% (after 500 h of aging). The mass loss rates of H4 and H5 were respectively 2.6% and 3.2% (after 500 h of aging). The germination rate of the H group(unmodified clay) was 7%, and the germination rate of the modified H1 group was 33%. With the increase of CTAC content, the germination rate of grass seeds gradually increased. And the germination rate of H4 group was up to 47%. With the increase of CTAC, the germination rate began to decline, and the germination rate of H5 group was 41%. This was mainly because CTAC could bond the loose clay particles together, thus significantly reducing the gap between clay particles and improving the water retention capacity of clay layer. It could provide necessary soil moisture for grass seed germination, so the germination rate of grass seed greatly increased. However, excessive CTAC would overfill the space of clay particles and reduce the permeability of the consolidated layer, so the germination rate of H5 began to decrease. The X-ray diffractometer analysis showed that the lamellar space of clay before and after modification changed from 1.2535 nm to about 1.4850 nm. It indicated that CTAC entered into the clay lamellae, which made the lamellae spacing become larger. Infrared spectrum analysis showed that the characteristic peaks of 2930 cm-1 and 2850 cm-1 were respectively asymmetric stretching vibration peak and symmetric stretching vibration peak ofv-CH2in CTAC, which were newly emerging in modified clay. Combined with X-ray diffractometer analysis, it could be seen that CTAC entered into the clay lamellae. The microscopic analysis showed that CTAC could bond the loose clay particles together through intercalating effect. The clay gaps were turned into hydrophobicity, which resulted in the increase of the water transport resistance. So the modified clay had better sand-fixation and water-retention performance. However too much CTAC blocked the space of clay particles, the permeability of clay decreased, so the germination rate of H5 decreased. Although the compressive strength and water retention performance of H5 is slightly better than H4, as a kind of sand fixation material, the most important performance is the survival rate of seedlings. Therefore, under the premise that all other performances meet the standard requirements, H4 with the highest germination rate is selected as the best treatment scheme. The results could provide reference for the application of the new sand-fixing materials.
    July 22, 2020 , DOI:
    Abstract:
    The development of intelligent agricultural pest monitoring technology is developing rapidly, and the bird monitoring technology is still in its infancy. In recent years, due to ecological improvement, the number of pheasant breeding has increased sharply. Its fondness for seeds and seedlings of wheat, corn, sweet potatoes and other crops has caused certain harm to agriculture. however, the traditional bird repellent methods have deficiencies in terms of efficiency and danger. An efficiency pheasant monitoring method combined with artificial intelligence is needed to provide early warning and expulsion of pheasants. Pheasant activities are mostly in the early morning and dusk under complex environment with protective color or habit of hiding. A pheasant monitoring method suitable for the deployment of embedded system is proposed in this paper. According to the behavior of pheasant, specific conditions required to monitor pheasants, the study proposed a pheasant monitoring method suitable for the deployment of embedded computing platforms which combine the enhanced Tiny-YOLOV3 target detection network to monitor pheasants. Due to the deployment on a mobile platform in the field environment, a lightweight network is required, while ensuring the accuracy and real-time monitoring. Therefore, according to the basic structure of the Tiny-YOLOV3 lightweight target detection network, a real-time monitoring network ET-YOLO for the emergence of pheasants in a complex field environment is proposed. The feature extraction net part deepens the net depth of Tiny-YOLOV3 feature extraction, increases the detection scale to improve the original net target detection accuracy. The net detection layer uses the detection method based on CenterNet structure to further improve the detection Measurement accuracy and speed. Using the field collection of pheasant images in various environments as dataset which including 6000 high resolution images of pheasant in different distances、angles and environments, through dataset augmentation, the pheasant monitoring dataset is produced. The experimental evaluation indicators are mainly tested and evaluated in terms of accuracy, real-time performance, and model size. The average detection accuracy, average detection speed, and detection model size of the pheasant are used for evaluation, the experimental results show that the average detection accuracy of ET-YOLO in the complex field environment is 86.5% and the average detection speed is 62 frames / s which is 15 percentage points higher than the average detection accuracy of Tiny-YOLOV3 before the improvement and the average detection speed is 2 frames/s higher than that of Tiny-YOLOV3 before the improvement. Compared with other state of the art target detection algorithms. The average detection accuracy is higher than YOLOV3, Faster-RCNN and SSD_MobileNetV2 by 1.5, 1.1 and 18 percentage points respectively. The average detection speed was 38, 47and 1 frame/s higher than YOLOV3, Faster-RCNN and SSD_MobileNetV2 respectively, the detection model size is 56 MB. Compared with other state of the art target detection algorithms, this method is suitable for deployment on embedded system equipped with agricultural robots and intelligent agricultural machines in terms of monitoring accuracy, real-time performance, and model size, which can efficiently monitor pheasants in complex environments.
    April 17, 2020 , DOI:
    Abstract:
    The mechanical properties of gypsum board was low, and cannot be used as load-bearing materials in construction. Plant fibers can be employed as the reinforcement to increase the mechanical properties of the gypsum board, but the improvement increment on the mechanical properties was limited because of the addition of gypsum retarders during the preparation of general particle-gypsum composites. The gypsum retarder solution deteriorated the morphology of gypsum crystals, and the gypsum crystals became shorter and wider, and then the overlapping area decreased among them. The general particle-gypsum composites still cannot be used in structural application. In order to increase the mechanical properties of the particle-gypsum composite, a two-step preparation process including pre-forming molding and moisture-curing was proposed in this study. The particle-gypsum composites with different MUF content and the particle/gypsum ratio was prepared, and the physical and mechanical properties was tested. The effects of melamine-urea-formaldehyde (MUF) content and the particle/gypsum ratio on mechanical properties of the particle-gypsum composites were analyzed by one-factor experiment. The results in the present study were compared with the requirements in three product standards and that in the reported literatures. The test results showed there was a positive relationship between the MUF content and the mechanical properties of the particle-gypsum composites, and the particle/gypsum ratio had a slight impact. The mechanical properties of the particle-gypsum composites with 15% and higher MUF content met the requirements of Standard LY/T 1598 (2011), and the values, except longitudinal modulus of rupture, were in accordance with the requirements of Standard LY/T 1580 (2010) when MUF content was 21% and above. The mechanical properties of the particle-gypsum composites reached E5.0-F16.0 grade according to the Standard GB/T 35216 (2017), when 33% and higher MUF content was used. The curves of bending load with deformation of gypsum boards exhibited linear elastic behavior due to the brittleness of gypsum crystals. All particle-gypsum composites in bending tests exhibited obvious non-linear behavior before the maximum load was reached, and the failure was ductile. The strengths of the composites in the present study were all higher than that in the reported literatures. Therefore, the particle-gypsum composites can be used as structural boards in construction. Based on the combination of mechanical properties and costs, the performance of the particle-gypsum composites with 33% MUF content and a particle/gypsum ratio of 0.30 were better, and the internal bond strength, modulus of rupture, modulus of elasticity, displacement ductility coefficient and 24 h thickness swelling of the particle-gypsum composite were 1.28 MPa, 16.5 MPa, 7350 MPa, 1.64 and 1.23%, respectively. After the new preparation process was employed, the mechanical properties of the particle-gypsum composites were increased greatly due to the increase of the strength of the gypsum continuous phase and the obvious improvement of the interfacial bonding strength between the particle reinforcement and the gypsum continuous phase. The microscopic images by Scanning Electron Microscope indicated that gypsum crystals in particle-gypsum composites were slender, when the new preparation process was employed. The gypsum crystals interlaced among them, and the contact area of the gypsum crystals was increased greatly with the increase of MUF content. Therefore, the gypsum continuous phase was strengthened. The amount of the gypsum on the surface of the wood particles was significantly increased with the increase of MUF content due to the bonding performance of MUF resin.
    April 16, 2020 , DOI:
    Abstract:
    Vegetation coverage has a direct impact on the quality of regional ecological environment. Dynamic monitoring of regional vegetation coverage changes and analysis of its influencing factors are of great significance for effectively carrying out ecological engineering construction and achieving sustainable development of ecological environment. Danjiangkou Reservoir is the core water source area of the Middle Route of South-to-North Water Transfer Project. Its ecological environment directly affects the water quality and water quantity of the water source area. At present, there are some problems in the study of NDVI dynamic change in this area, such as short research time and inadequate quantitative evaluation of human activities. Based on EOT algorithm, taking Danjiangkou water source area as the research area, a 1 km resolution NDVI data set from 1982 to 2018 was constructed using GIMMS NDVI and MODIS NDVI data. On this basis, the characteristics of NDVI changes in the study area from 1982 to 2018, climate factors and human activities factors were analyzed, respectively. The results show that: NDVI fluctuated upward from 1982 to 2018, and the trend was 0.0029 year-1 (P < 0.05). Spatially, 89.93% of the annual average NDVI showed an increasing trend. 10.06% of the annual average NDVI showed a decreasing trend. In terms of influencing factors, climatic factors are the main factors affecting NDVI change in the whole region, and the influence of temperature on NDVI of vegetation is greater than that of precipitation. Temperature and precipitation have significant spatial heterogeneity on NDVI. Spatially, temperature is mainly positivel correlated with the areas around Hanzhong Basin in the west, Ankang City in the middle, Shangzhou City in the north and Zhuxi County in the south, while other regions have low correlation.Precipitation is negatively correlated with Danjiangkou Reservoir and Shiyan City, while the correlation is low in other regions. The residual method was used to separate the effects of climate and human factors on regional NDVI. It was found that the comprehensive contribution of climate factors and human activities factors was 92.14% and 7.86% at the whole regional scale during the study period. However, in the regions with significant changes in NDVI, the comprehensive contribution of climate factors and human activities factors was comparable. In recent years, human activities in the region have been increasing, while the influence of climate factors is gradually declining. Human activities have dual effects on regional NDVI. 67.74% of the regional human activities in the study area have positive effects on NDVI. The positive effects are reflected in a series of ecological protection and construction engineering measures to restore the ecological environment. 32.26% of the regional human activities in the study area have negative effects, and the negative effects are reflected in the development of society. A series of unreasonable production activities carried out at the economic level.
    April 16, 2020 , DOI:
    Abstract:
    Grain reserves is an important material foundation for ensuring food security, and food security is a major prerequisite for national security. The fatty acid content is a sensitive indicator of the changes of grain quality. Therefore, in order to achieve safe and green grain storage, real-time understanding of the fatty acid content of stored grain is significant for the safety of grain during storage. In this paper, 4 prediction models such as multiple linear regression(MLR), artificial neural network (ANN), support vector regression (SVR) and least square support vector regression(LSSVR) were applied to predict the fatty acid content of stored rice, and the predictive performances of these 4 prediction models were compared based on coefficient of determination(R2), mean absolute error (MAE), mean absolute percentage error and root mean square error (RMSE), which were measured by the difference between the observed and the corresponding predicted values in the test set. First of all, totally 201 rice storage data were collected from 35 granaries in 5 grain depots in the three northeastern provinces of China. In these storage data, each data contained 10 characteristics, which were warehousing month, initial moisture, initial fatty acid value, detected moisture, stored effective accumulated temperature, storage time, detected grain temperature, detected granary temperature, detected month and detected fatty acid value, respectively. Then, we analyzed the correlation between these predictive factors based on the Pearson correlation coefficient. However, we found that there were strong correlations between some predictive factors. In order to eliminate redundant information, we reduced the dimension of predictive factors by principal components analysis (PCA), and 4 key predictive factors which were initial moisture, initial fatty acid value, stored effective accumulated temperature, detected grain temperature were obtained after PCA dimension reduction. Finally, the key predictive factors were normalized and randomly segmented 80% used for training, 20% for testing, and the PSO algorithm were adopted to optimize the parameters of SVR and LSSVR before simulation experiment, the optimal parameters for the SVR model were found based on C value of 569.3, ε of 0.05 and γ of 2.7, and the optimal parameters for the LSSVR model were found based on C’ value of 1000.0 and γ’ of 0.003, respectively. For testing the data set, the experimental results showed that the predictive performance of LSSVR of which the coefficient of determination values of 0.911, MAE values of 0.275(KOH)/(mg/100g), MAPE values of 1.604% and RMSE values of 0.348(KOH)/(mg/100g) was significantly better than SVR and ANN, and was slightly better than MLR. The various indicators revealed that the LSSVR and MLR had better predictive effect on fatty acid content of stored rice, and SVR was the worst among all models. It concluded that the LSSVR and MLR had high forecast accuracy and strong reliability in prediction of fatty acid content of rice, they all can be used as a method for predicting fatty acid content during rice storage. This study realizes the prediction of fatty acid content of stored rice and provides a reference for scientific and safe green storage in the future.
    March 25, 2020 , DOI:
    Abstract:
    In order to make full use of solar energy and improve the energy efficiency of solar heat pump system, an energy storage solar heat pump water heating system with inserted oscillating heat pipe is proposed, which integrates solar collector, energy storage tank and oscillating heat pipe together reasonably and effectively. The system can store solar energy with the phase change materials (PCM) filled in solar collector, transfer heat efficiently by oscillating heat pipe and switch operation mode according to solar radiation, and can realize the maximum utilization of solar energy in different seasons. In summer, enough heat is transferred or stored during the day to release at night by PCM in solar collector, which is directly used to heat the circulating water through the oscillating heat pipe heat exchanger. In winter, the heat transferred or stored during the day to release at night by PCM in solar collector is low, and the heat is transferred to the heat pump evaporator by the oscillating heat pipe heat exchanger to improve the evaporation temperature of the heat pump, and thus the overall performance of the system is improved. A test rig has also been established for the performance measurement of energy storage solar heat pump water heating system with inserted oscillating heat pipe. Paraffin is chose as phase change material of the system under the consideration of capacity, phase change temperature and latent heat of phase change. Experimental study has been carried out for two years under winter conditions in Nanjing, one year for the test rig without PCMs and another year with PCMs. Under similar environmental conditions (solar radiation intensity, fluctuation and ambient temperature), the variations of the instantaneous collecting efficiency, average collecting efficiency, COP (coefficient of performance) and water temperature of the system filling or not filling PCM with the fluctuation of solar radiation are compared and studied. The comparison and experimental results show that in winter daytime under similar solar radiation intensity, fluctuation and ambient temperature, the instantaneous collecting efficiency fluctuation with PCM is 61.5% less than that of the system without PCM, which can overcome can overcome the instantaneous influence of the fluctuation of solar radiation intensity on the system. And the average collecting efficiency with PCM is 25% higher than that of the system without PCM. At winter night, under similar operation conditions, COP of the system filled with PCM is over 3.0, which is nearly twice as high as that of the system without PCM, and make water temperature reach 50℃ in a shorter time, shortening the time by more than 20%. The results can provide theoretical basis for the popularization and application of solar energy heat pump system.
    October 16, 2019 , DOI:
    Abstract:
    Column chromatography is based on the difference of physicochemical properties of each component in the mixture. The mixture is separated and purified after multiple distributions by using the different distribution coefficients of each component in the stationary phase and mobile phase. The starch was hydrolyzed by amylase after retrogradation under high pressure and humidity. The hydrogen bond of retrograde starch was opened in alkali solution to dissolve the retrograde starch, and the solution was adjusted to neutral next. Amylose with narrow molecular weight distribution was obtained by adding n-butanol to the precipitate. While, amylopectin with narrow molecular weight distribution was prepared by adding ethanol to the supernatant. In order to narrow the molecular weight distribution of amylose and amylopectin in sweet potato furtherly, column chromatography was used to separate them respectively. The results show that the artificial zeolite with 1-3 mm particle size is suitable for the separation of amylopectin, while artificial zeolite with 4-6 mm for amylose. After separated by column chromatography, the yields of both amylose and amylopectin were more than 2.4% respectively. In the course of separation, amylose with higher DP adsorbed on the macrozeolite surface. It was eluted out from the mixture first for the weaker adsorption force. Amylose with lower DP entered into the small holes of macrozeolite, and was eluted out subsequently for the stronger adsorption force. When separated by small zeolite column chromatography, the amylopectin components of F1b with small molecular weight and high homogeneity were eluted out first. While, amylopectin components F2b with large molecular weight and low homogeneity were eluted out first, indicating that the branching degree of amylopectin also played a certain role in the separation of starch components by zeolite column chromatography. X-ray diffraction showed that there were strong peaks of amylose components at the diffraction angles (2??? of 18.9°, 23.4°, 27.2°, 29.3°, 32.3°, 33.8°. There were obvious peaks of amylopectin components at around 21.6°, 22.9°, 23.9°, 26.5°, 27.1°, 29.3°, 34.1°, 35.8°, 39.5°. The molecular weight distribution index (PDI) of sweet potato amylose was close to 1.0 at the same time. Sweet potato amylopectin with extreme narrow molecular weight distribution can be prepared by artificial zeolite column chromatography. These kinds of starch exhibits X-ray diffraction peaks similar to metal salts, which can be used as materials to study the spatial structure of starch macromolecule in depth. Micrographs showed that amylose was composed of many linear molecules and presents typical linear “wicker-like” morphology, while amylopectin showed “branch-like” shape. The results provide a simple and efficient method for the preparing of amylose and amylopectin with extreme narrow molecular weight distribution. It brings about favorable conditions for further exploring morphological changes of starch macromolecules during aggregation progress.
    October 16, 2019 , DOI:
    Abstract:
    Vinegar plays an important role in our daily diet. Solid-state fermentation of vinegar using reactors has several advantages over the traditional methods, which include shorter fermentation process, and good controlled working environment. In order to fully understand the dynamic changes of main components and flavor compounds during the solid-state fermentation of vinegar in rotary drum reactor, samples were taken throughout the fermentation process. Alcohol, total acid, reducing sugar, amino nitrogen, organic acid and volatile flavor in the process of vinegar fermentation were studied by high performance liquid chromatography, solid-phase microextraction, and gas chromatography-mass spectrometry. Meanwhile, principal component analysis was carried out to explore the difference of volatile flavor in vinegar at different fermentation stages. The results showed that the fermentation process can be divided into three stages: starch saccharification, alcohol fermentation, and oxidation of ethanol to acetic acid. The alcohol content increased rapidly within 0-4 days of fermentation, then decreased gradually to zero until the end of fermentation. The total acid content showed a sharp increase tendency first, followed by a slight increase at the late stage of fermentation. The reducing sugar content decreased rapidly at first, then gradually increased during acetic acid fermentation, and finally gradually decreased. The amino nitrogen increased rapidly at first, followed by a gradual decrease at the end of fermentation. Seven organic acids were detected in our research, including acetic acid, lactic acid, oxalic acid, succinic acid, tartaric acid, citric acid, and malic acid. Among them, acetic acid and lactic acid were the main organic acids in the whole fermentation process. The lactic acid content increased rapidly first, and became the dominant organic acid in the alcohol fermentation stage. Then it showed a gradual decrease until the end of fermentation. For acetic acid, a gradual increase tendency was observed during the whole fermentation process, which accounted for 64.87% of all the organic acids contents. Compared with those, the content of other organic acids was less, and the variation during fermentation was relatively small. These organic acids were also crucial for the formation of characteristic taste of vinegar. A total of 64 flavor volatile substances were detected, including 25 esters, 12 alcohols, 6 acids, 5 phenols, 5 aldehydes, 6 ketones and 5 heterocyclic compounds. The principal component analysis results showed that the most dominant ones responsible for volatile flavor in the early, middle, and later stage of fermentation were alcohols, esters and aldehydes, and acids, respectively. Other volatile compounds, such as aldehydes, phenols, ketones, heterocycle, were present in small amounts during vinegar fermentation based on the reactor. However, they also play a vital role in the formation of special flavor for vinegar. This is the first report to study the dynamic changes of vinegar quality during fermentation process based on a reactor. The results would enhance our understanding of the fermentation property of rotary drum solid-state fermentation vinegar reactor, which may be helpful for the improvement and effective management of reactor to promote its industrial application.
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    2010,26(11):1-7, DOI:
    [Abstract] (32257) [HTML] (0) [PDF 0.00 Byte] (8862)
    Abstract:
    The problems and challenges for agricultural water management are markedly different from 50 years ago. To meet the increasing global demand for food, new challenges have been coming: increasing farmers’ income, boosting rural economy, reducing poverty, adapting climate change and protecting the ecological environment, under the conditions of the scare water resources. Therefore, the improvement of strategies and countermeasures relevant to the development of agricultural water management is nessary starting from the thinking of interdisciplinary and various sectors. The strategies include that developing water-saving agriculture, maintaining the service functions of the ecological system, increasing investment in irrigation, promoting rain-fed agriculture, improving and increasing water productivity, reducing poor population, preventing and alleviating the degradation of land and water environmental quality, reducing the risk in waste water irrigation, and strengthening policy and institution building. The efforts in improving agricultural water management and increasing agricultural productivity depend on the rational selection of the above strategies and the benefit tradeoffs.
    2013,29(14):203-209, DOI: 10.3969/j.issn.1002-6819.2013.14.026
    [Abstract] (26498) [HTML] (0) [PDF 392.78 K] (6051)
    Abstract:
    Abstract: The arable land per capita among the rural migrants located in the Three Gorges Reservoirs Area is only about 386.7 m2. The contradiction between people and their land is severe. After the impoundment of the Three Gorges Project, the water flow and the self-purification ability of the Yangtze River got slowed and declined which resulted in an overmuch growth of the green algae in main tributaries of the Yangtze River. Besides, to meet the electricity generation need in the dry winter or spring, and to prevent the deluge in the rainy summer, the Three Gorges Reservoir impound in the winter and spring, disembogue in the summer. Owing to this, the hydro-fluctuation belt along the river always outcrop into land in the hot and humid rainy summer, hence the hydro-fluctuation belt fail to intercept, absorb and filtrate the agricultural surface source pollution, which cause the increased pollution in the Yangtze River. The contradiction of the economic development and the environmental protection is severe.This research considered the Three Gorges Reservoir Area, the hydro-fluctuation area and the ecological barriers area as an entirety, and combined the specialty agriculture industries, such as: citrus, livestock and fishing industry with the newly developed agricultural technologies, like the orange residue self-drying and high temperature fermentation under aerobic environment technology along with its dedicated organic fertilizers, the biogas slurry pipeline irrigation fertilization integrated device, citrus nutrition diagnosis testing fertilization technology and the new variety of submergence-tolerant pasture, on the basis of the principles of ecological agriculture and recycling economy. A recycling agriculture ecosystems demonstration area was built in the Dachang town, Wushan county, the hinterland of the Three Groges. Relying on the greening the Yangtze River citrus belt project, the hydro-fluctuation belt management project and forced removal of the cage fish culture facilities along the river project, we build three ecological economic zones which are reservoir bank citrus plantations, hydro-fluctuation belt wetland pastures and natural fishery around the reservoir bank to develop specialty industry economy.In this project we integrated "pig-biogas-fruit-residue-feed", "fruit-residue-fertilizer", "livestock-biogas-fruit-grass" and water cycle, developing a new four-chain crossed recycling economy networking mode, and an anti-season hydro-fluctuation area ecologically recycling agriculture progression mode. By using the farming manure as the fertilizer and the irrigation water of the citrus, and using the waste of citrus processing or hydro-fluctuation belt pasture as the feedings of the livestock, we established a system that using the waste of the previous level as the production resource in current level. Due to this system we set up a citrus, pigs, grazing livestock, Yangtze fish and other specialty industrial that industrial symbiosis, coupling elements, the overall recycling and comprehensive utilization of industrial ecological chain in the very area. Also by building biogas project, citrus barrier forest, cut flood engineering, wetland pastures and fishery as 5-layer intercept network, we can block, absorb and digest the area source pollution. With this project we are able to increase the vegetation coverage of the reservoir bank, the income of the migrants and protect the environment of the Three Gorges Reservoirs Area.The established specialty recycling agriculture ecological demonstration area in Dachang Lake, Wushan county will cover the core area of 135 hm2. The 2 km long hydro-fluctuation area will be fully covered by the pasture and the cover ratio of the forest will be over 80 percent. The whole area will be fully covered by plants, and those wastes like farming excrement, waste straw, citrus residue will be completely reutilized and achieve the accomplishment of zero emission. Besides, the citrus yield in the demonstration area will be about 30 tons each hectare and the yield of pasture will be about 33 tons each hectare, which means that the output value per hectare will be over 150,000 Yuan. This area is showing the possibility that increasing the migrants' income and purifying the Yangtze River synchronously.
    2007,23(5):150-153, DOI:
    [Abstract] (20834) [HTML] (0) [PDF 0.00 Byte] (7578)
    Abstract:
    Apple storage quality properties(including hardness, moisture, soluble solid, total acid) were estimated through the mechanical properties of apple(including the maximum of compression, the yield force, the elastic modulus). An artificial neural network model of storage quality properties was built by the optimization algorithm of L-M(levernberg marquardt) BP neural network. The mechanical properties and the apple storage quality properties measured in the experiment were adopted as input and output to establish the BP neural network. The simulated results show that this neural network make a good estimation of apple storage quality properties through mechanical properties. When tested by five groups of Non-sample data, the relative error between the estimation of this model and the measured value is below 5%, which meets the accuracy requirement of apple storage quality properties in engineering application.
    2007,23(2):1-5, DOI:
    [Abstract] (17912) [HTML] (0) [PDF 0.00 Byte] (5418)
    Abstract:
    In the research of the soil erosion and soil losses, the runoff velocity of slope is an indispensable hydrodynamic parameter in the runoff computation and the soil erosion forecast. There is still no special instrument which is widely used to measure runoff velocity. It is very significant to construct a fast measurement instrument on runoff velocity. On the basis of correlation theory, the runoff velocity measurement system was established based on virtual instrument LabVIEW. The system uses the conductance sensor to acquire signal. Effect of the space between conductance sensors on the measurement system and the runoff velocity under five sediment concentrations were studied. Results indicate that the suitable sediment concentration scope of the measurement system is 0~250 kg/m3 and the greatest relative error of the system is 4.5%. While taking the flow velocity measured by the dye tracer technique as standard value to correct the correlation velocity, the greatest relative error of the proved velocity reduces to 3.81%.
    2016,32(1):46-53, DOI: 10.11975/j.issn.1002-6819.2016.01.006
    [Abstract] (17546) [HTML] (0) [PDF 5.12 M] (3444)
    Abstract:
    The application of the path tracking technology on agricultural vehicle makes the robot replace farmers for field operation, and the accuracy, production efficiency and dependability about farming automation are improved effectively.Meanwhile the labor time, labor intensity of drivers and the production cost are saved.The path tracking of agricultural vehicle was studied in an operating condition, and a variety of sensors were installed on the car features of the external environment.Then it generated a four-element in state space by the target path which was given for controling the agricultural vehicles to track the target path automaticly according to the theory of optimal navigation control.The location method of GPS/INS was selected, the navigation system was developed, and the experiment was finished in 2014.According to the needs of automatic walking positioning system, a variety of sensors has been chosen, including the inertial sensor, angle sensor and GPS sensor.Then the serial program was writen to collect the signal from the sensors and calibrate them.In order to meet the requirements of vehicle navigation system, the positioning system with low cost and high precision was developed.The hardware of the system consisted of two GPS modules, two Zigbee wireless transmission modules and an inertial sensor.The data from the sensors are filtered and fused, and finally accurate, reliable vehicle position data was got.The tracking controller based on preview control was designed to obtain the future values and target values of the vehicle.With the target path and its curvature, the feed forward control value was got.There was an error between the current state and the state of vehicle target path that was needed to use LQR for elimination.The performance of the path following controller was simulated by Matlab, then the maximum lateral error was 0.16 m and 0.27 m at the speed of 0.5 m/s and 1 m/s respectively.The results showed that the control method was feasible.The steering control system was designed based on steer-by-wire(SBW) after the study of vehicle navigation control principle.SBW removed out mechanical connection between steering wheel and steering front wheel.It used motors to control front wheel angle and simulated force characteristic.Compared with traditional steering system, SBW had characteristics of ideal steering ratio and active steering control according to vehicle state parameters, and improved safety of driving and handling stability.The strategy of BLDCM was designed in order to make actual front angle follow the desired angle better.PID control and sliding mode variable structure control were applied in strategy of BLDCM and the result of simulation showed that sliding mode variable structure control was better than PID control.This paper designed the electronic control unit of SBW based on chip of MC9S12XET256, mainly including peripheral circuit of MCU, CAN communication circuit, drive circuit of BLDCM, power circuit, signal acquisition and processing circuit, current sampling circuit of motor.Based on the requirement of joint simulation, we designed a bench test for control strategy and hardware, software of ECU in 2015.The results of test bench showed that angle correction was similar with the result of simulation and sliding mode variable structure control was better than PID control in following front angle.Finally, the vehicle steering control test and the vehicle path tracking control test were carried out based on vehicle test platform, which was built personally.The vehicle path tracking system was based on the Windows platform, using Microsoft Visual Studio as the development environment.The integrated navigation system was validated and the test data showed that the integrated navigation system had a high positioning accuracy and the steering system had a reliable tracking performance.The final navigation and positioning accuracy of integrated navigation system was around 0.1 m to 0.5 m and the response speed of the whole system was about 0.1s .The results proved that the system could meet the requirements of agricultural vehicle path tracking control system.
    2019,35(18):143-150, DOI: 10.11975/j.issn.1002-6819.2019.18.018
    [Abstract] (17213) [HTML] (0) [PDF 3.96 M] (5400)
    Abstract:
    Rosa roxburghii is widely distributed in warm temperate zone and subtropical zone, mainly in Guizhou, Yunnan, Sichuan and other places in China. Panxian and Longli are the most abundant the most varieties and the highest yield Rosa roxburghii resources in Guizhou. The harvesting of Rosa roxburghii fruit is the most time-consuming and labor-consuming work in Rosa roxburghii production, and its labor input accounts for 50%-70% of the production process. Hand-picking of Rosa roxburghii fruit is of high cost, high labor intensity and low picking efficiency. In recent years, convolutional neural network has been widely used in target recognition and detection. However, there is no relevant literature on the application of neural network in Rosa roxburghii fruit recognition. In this paper, in order to realize rapid and accurate identification of Rosa roxburghii fruits in natural environment, according to the characteristics of Rosa roxburghii fruits, the structure and parameters of VGG16, VGG_CNN_M1024 and ZF network models under the framework of Faster RCNN were optimized by comparing them. The convolutional neural network adopted bilinear interpolation method and selected alternating optimization training method of Faster RCNN. ROI Pooling in convolutional neural network is improved to ROI Align regional feature aggregation. Finally, VGG16 network model is selected to make the target rectangular box in the detection result more accurate. 6 540 (80%) of 8 175 samples were selected randomly as training validation set (trainval), the remaining 20% as test set, 80% as training set, the remaining 20% as validation set, and the remaining 300 samples that were not trained were used to test the final model. The recognition accuracy of the network model for 11 Rosa roxburghii fruits was 94.00%, 90.85%, 83.74%, 98.55%, 96.42%, 98.43%, 89.18%, 90.61%, 100.00%, 88.47% and 90.91%, respectively. The average recognition accuracy was 92.01%. The results showed that the recognition model trained by the improved algorithm had the lowest recall rate of 81.40%, the highest recall rate of 96.93%, the lowest accuracy rate of 85.63%, the highest 95.53%, and the lowest F1 value of 87.50%, the highest 94.99%. Faster RCNN (VGG16 network) has high recognition accuracy for Rosa roxburghii fruit, reaching 95.16%. The recognition speed of single fruit is faster, and the average recognition time of each Rosa roxburghii fruit is about 0.2 seconds. The average time has some advantages, which is 0.07 s faster than the methods of Fu Longsheng. In this paper, a Faster RCNN Rosa roxburghii fruit recognition network model based on improved VGG16 is proposed, which is suitable for Rosa roxburghii fruit recognition model training. The algorithm proposed in this paper has good recognition effect for Rosa roxburghii fruit under weak and strong illumination conditions, and is suitable for effective recognition and detection of Rosa roxburghii fruit in complex rural environment. This paper is the first study on the depth extraction of Rosa roxburghii fruit image features by using convolution neural network. This research has high recognition rate and good real-time performance under natural conditions, and can meet the requirements of automatic identification and positioning picking of Rosa roxburghii fruit. It lays a certain foundation for intelligent identification and picking of Rosa roxburghii fruit, and opens a new journey for the research of automatic picking technology of Rosa roxburghii fruit.
    2016,32(9):130-135, DOI: 10.11975/j.issn.1002-6819.2016.09.018
    [Abstract] (17002) [HTML] (0) [PDF 361.61 K] (2232)
    Abstract:
    Abstract: To assess the effects of different straw return modes on the content of soil organic carbon and the fraction of soil active carbon, we investigated 4 different straw return modes, non-straw return (CK), direct straw return (CS), straw return after mushroom cultivation (CMS), and straw return after livestock digestion (CGS) using field plot experiment. The results showed that different straw return modes all increased the content of soil organic carbon, but the increases in soil organic carbon content by different straw return modes did not exhibit significant difference (P>0.05). The increases in soil organic carbon content were found in the order of CGS > CMS > CS > CK. In comparison to CK mode, the contents of soil organic carbon with CS, CMS and CGS modes increased by 9.0%, 23.9% and 26.7%, respectively. In addition, different straw return modes all improved the content of soil active carbon. Under different straw return modes, the contents of dissolved organic carbon (DOC) were in the order of CS > CMS > CGS > CK, and significant differences were observed among different return modes (P<0.01). Compared to CK mode, the contents of DOC in the treatments of CS, CMS and CGS increased by 64.6%, 29.4% and 8.9%, respectively. The contents of microbial biomass carbon (MBC) followed the order of CMS > CGS > CS > CK, and their differences were significant (P<0.05). The contents of MBC in the treatments of CS, CMS and CGS increased by 28.9%, 84.7%, and 59.3%, respectively, compared to the CK treatment. Similarly, the contents of soil easily oxidizable carbon (EOC) were in the order of CMS > CS > CGS > CK, and their differences were significant (P<0.01). Compared to CK mode, the contents of EOC in the treatments of CS, CMS and CGS increased by 24.1%, 55.7%and 9.3%, respectively. Straw return modes also significantly affected the fraction of soil active carbon in the soil total organic carbon (TOC) and changed the quality of soil organic carbon. Under different straw return modes, the ratios of DOC/TOC, MBC/TOC and EOC/TOC were in the orders of CS > CMS > CK > CGS, CMS > CGS > CS > CK and CMS > CS > CK > CGS, respectively. From the perspective of improving soil quality, CMS is the recommended mode, which has the greatest ratios of MBC/TOC and EOC/TOC, as well as a higher soil carbon effectiveness that facilitates the carbon utilization by the microorganisms, thus benefiting the growth of crops. On the other hand, from the perspective of soil carbon sequestration, CGS is the recommended mode, which has the lowest fraction of DOC/TOC and the highest content of soil organic carbon, thus facilitating the carbon sequestration. The results of the study can provide the basic data for the rational and efficient utilization of straw, as well as the improvement of the quality of agricultural soil carbon pool.
    2015,31(16):78-85, DOI: 10.11975/j.issn.1002-6819.2015.16.012
    [Abstract] (16741) [HTML] (0) [PDF 522.80 K] (2596)
    Abstract:
    A typical dynamic characteristic of horizontal axis wind turbine shows up under yaw condition. Prediction accuracy is low for momentum-blade element theory and related engineering prediction model. In order to improve the prediction accuracy of dynamic load characteristics, the whole wind turbine models, based on the experiment about MEXICO (model experiments in controlled conditions) rotor in 2006, are established by three-dimensional software called Pro/E. under different yaw conditions, i.e. yaw angle of 0, 15, 30 and 45 degree. ICEM CFD (integrated computer engineering and manufacturing code for computational fluid dynamics) is applied to grid division. The rotating domain containing rotor part is meshed into hexahedral grids, and the static domain containing part of wheel hub, tower and outflow field is meshed into tetrahedral grids. When the grid size of the first layer of blade surface is set as 5×10-6 m to ensure the first dimensionless size near the wall Y+<0.5 on the wall, the 2 numbers of grids are determined by the error of axial load on the airfoil in the 60% section of blades, which respectively are 6 572 451 and 2 961 385. The aerodynamic performance of models under rated condition is simulated by ANSYS CFX with the turbulence model of SST (shear stress transport), high resolution is chosen as advection scheme, and transient rotor stator as the domain interface method. The results are converted into data, processed and analyzed by MATLAB. Finally the following conclusions are drawn. The distributions of pressure coefficients along the airfoil chord in different blade sections calculated by CFD method are in good agreement with the experimental measurements, and the error on the suction surface of airfoil is mainly caused by stall separation occurring on the pressure surface of airfoil. With the increasing of yaw angle, the pressure coefficients of the suction side are increasing and the location of minimum pressure coefficient moves to airfoil trailing edge slightly. For the pressure side, the pressure coefficients increase at first and then decrease, and the location of maximum pressure coefficient moves to airfoil leading edge slightly. The axial load coefficients and tangential load coefficients of blades first decrease and then increase and then decrease again with the increase of the azimuthal angle. With the increase of the yaw angle, the axial and tangential load coefficients are both reduced. When the yaw angle is within 30°, the relative error of axial load coefficients is in the range of ±5% and the relative error of tangential load coefficients is in the range of ±15%. CFD method is higher than BEM (blade element momentum) method in forecasting accuracy of dynamic load calculation. Under yaw condition, the hysteresis characteristic of airfoil lift and drag in blade root is more remarkable than blade tip, while the variation range of the angle of attack in blade root is much less than that in blade tip. This characteristic must be considered when BEM method is used to predict wind turbine performance. For axial inflow condition, CFD method can well predict the average speed, but restricted by turbulence model and the wake model, CFD calculation did not show the velocity characteristics of rotating vortex shedding from wind turbine impeller under yaw condition. The study provides a data support to build up the forecast model on the engineering and provides the basis for wind turbine design under yaw condition.
    2015,31(9):201-208, DOI: 10.11975/j.issn.1002-6819.2015.09.031
    [Abstract] (16562) [HTML] (0) [PDF 3.61 M] (3527)
    Abstract:
    Abstract: As one of the most effective cooling method, the fan-pad evaporative cooling system has been widely used to provide a suitable growth environment for greenhouse crops. An optimization method of the fan-pad cooling system based on computational fluid dynamics (CFD) was proposed to improve the cooling performance inside the greenhouse in summer. The Reynolds-averaged Navier-Stokes equations were solved using finite volume method (FVM). Due to the remarkable effect of gravitation on the microclimate distribution inside the greenhouse, the Boussinesq hypothesis was taken into account. The standard k-ε turbulent model was selected to predict the distribution of air flow. Solar ray tracing was applied to load the solar radiation model, while the discrete ordinate model was selected for considering the effect of thermal radiation. Crops in the greenhouse were regarded as the porous medium, which was governed by the Darcy-Forcheimier equation in the CFD model. A three-dimension greenhouse model was developed to simulate the microclimate distribution and air circulation inside the greenhouse adopting fan-pad cooling system. The verification experiment was conducted in a Venlo-type greenhouse in the campus of Zhejiang University of Technology (30°14′N, 120°09′E) from 12:30 to 13:30 on July 23, 2012. Thirteen observation points of T1-T10 and TH1-TH3 were set up in the experimental greenhouse to validate the simulated air temperature and velocity. The errors between simulated and measured air temperature at the observation points varied from 0.7 to 2℃, and the errors of air velocity were less than 0.13 m/s. Compared with the measured values, the absolute mean errors of simulated temperature and air velocity were less than 4% and 6% respectively. It proved that the CFD method is reliable to estimate the distribution of air velocity and temperature in the greenhouse. The validated CFD model was then used to further analyze the cooling performance of different greenhouse cases in terms of the greenhouse lengths, the evaporative pad areas and the greenhouse ventilation rates. The indoor environment with the temperature of below 30℃ and the velocity of below 1 m/s was suitable for crop growth, and this condition was used as a criterion for optimal design. Based on the orthogonal test method, greenhouse cases with different greenhouse lengths, evaporative pad areas and air velocities of fans were classified and simulated to analyze their relations. The simulations illustrated that the greenhouse ventilation rate of 153.1 m3/(m2·h) and the minimum pad area of 6 m2 can meet the cooling requirement in a Venlo-type greenhouse with 24 m length and 9.6 m width. In contrast with greenhouse of 70 m length, the maximum pad area of 13.5 m2 had to be configured, because the greenhouse with smaller evaporative pad need combine with the fan's velocity of more than 105 m3/(m2·h). According to the relations among greenhouse length, evaporative pad area and fan's velocity resulted from CFD analysis; the fitted results could be achieved to design the fan-pad evaporative cooling system in the greenhouse in eastern China. The fitting optimization showed good agreement with the previous corresponding research results, which demonstrated that CFD technique was rational and reliable to design the fan-pad evaporative cooling system in the greenhouse.
    2015,31(15):201-207, DOI: 10.11975/j.issn.1002-6819.2015.15.028
    [Abstract] (16488) [HTML] (0) [PDF 772.45 K] (2312)
    Abstract:
    Abstract: At present, large quantities of straws are burned in field in China, which not only wastes a renewable resource, but also causes serious air pollution. Anaerobic digestion of straws is an alternative method that may produce a clean fuel for energy generation. Currently, more research on impact of digestion for quality content of total solid of manure or mixed materials for the fermentation substrate has been studied, but research is limited in continuous stirred tank reactor for a single type of feedstock. Although the characteristics of anaerobic digestion and properties of gas production at the process of continuous stirred tank reactor and semi- continuous feeding mode has been examined for crushed straw and silage straw as the fermentation substrate, but the operation parameters of such system has not been determined. Thus, in order to obtain the corresponding relationship between solid matter retention time for substrate and the characteristics of gas production, a comparative study to determine biogas production in batch fermentation and semi-continuous fermentation process was carried out under medium temperature conditions with rice straw as feedstock. The effect of quality content of total solid in the batch and continuous biogas fermentation of straws was studied. The volume of gas production rate and the rate of raw material gas production were used as characteristic indicators in order to obtain parameter on optimum quality content of total solid and solid matter retention time for biogas plant with straws. The results showed that fermentation concentration of single straw type used for anaerobic fermentation raw material influenced the gas volume rate under the condition of batch fermentation. With the increase of total solid concentration, the volume of gas production rate was increased in batch fermentation process, but the trend of the increase was gradually decreasing. The volume of gas production rate was improved under condition of intermittent stirred compared with static batch fermentation. Especially, the improving effect was more obvious for the group of high-concentration of TS. However, the volume of gas production rate was more improved for the group of high-concentration of TS under semi-continuous feed conditions, but with the solid matter retention time (SRT) shortened, the rate of raw material gas production with every treatment was gradually decreased. Considering the characteristics of gas production and engineering applications, it was recommended that the concentration of batch fermentation should not exceed 8% for pure straw. For semi-continuous fermentation, if the straw composition in total solids content was 8%, SRT was designed as 20 days (the volume of gas production rate of 1.00 m3/(m3·d)). If the total solids content was 6%, SRT was designed as 15 days (the volume of gas production rate of 0.75 m3/(m3·d). The operating parameters provided an operational reference for biogas plant only with straw.
    2015,31(16):96-101, DOI: 10.11975/j.issn.1002-6819.2015.16.014
    [Abstract] (16301) [HTML] (0) [PDF 395.08 K] (2181)
    Abstract:
    High-speed solenoid valve (HSV) is the key component of electronic control fuel injection system for diesel engine. Improving the dynamic response speed of HSV will be able to achieve higher injection precision and more flexible fuel injection law, thus reducing gas emissions of diesel engine and improving its fuel economy. However, HSV is the complex coupling system of electric field, magnetic field, mechanical movement and flow field, and the interactions of multiple parameters exist between the fields for HSV. To improve the dynamic response speed of HSV is a complex optimization problem of multiple physical field and multiple parameters. A zero-dimensional approximation coupling model of HSV can be developed instead of the CAE (computer aided education) models or physical experiments, which conduces to achieve the efficient prediction and global optimization of performances. So the approximation model method was employed in this paper. First, the structure and principle of HSV for electronic unit pump of diesel engine were presented. Second, the three-dimensional (3D) finite element model of HSV was developed to calculate the electromagnetic force, and its accuracy was verified by means of the comparison with experimental data. Third, 3 major methods of experimental design, i.e. central composite faced-centered design (CCF), central composite inscribed design (CCI) and optimal latin hypercube design (OLH), and 3 typical approximation methods, i.e. quadratic polynomial response surface model (RSM), Kriging model (KR) and radial basis function model (RBF) were introduced. Fourth, 6 key parameters including 2 field coupling parameters, i.e. working air gap and drive current, and 4 structure parameters, i.e. coil turns, side pole radius, thickness and radius of armature were determined for establishing the approximate models. Next, 6 groups of sample points were designed, whose response values of electromagnetic forces were obtained by the 3D finite element model of HSV. Four of the groups were designed with different sizes by the OLH, and the other 2 groups were designed by the CCF and CCI. Then, 18 groups of electromagnetic force approximation models were developed by combining the 6 groups of experimental design with the 3 typical approximation methods introduced. To compare the accuracy of approximation models, 3 kinds of evaluation indices were introduced. They were multiple correlation coefficient, average absolute error and root mean square error respectively. In the end, the effects of different sample point sizes, experimental design methods and approximate methods on the accuracy of electromagnetic force approximation models were analyzed in detail. It is concluded that the accuracy of approximate model doesn't increase monotonically with the increase of the set size of sample points, and too many sample points maybe leads to the decrease of the accuracy of approximate model; the OLH has good adaptability with the KR and RBF, and can be given priority for developing approximation models. In addition, the best solution for establishing electromagnetic force approximation model of HSV is the combination of the KR and OLH, whose size of sample points is 1.5 times of the minimum sample points required by the quadratic polynomial response surface model. Its multiple correlation coefficient, average absolute error and root mean square error are 0.97, 0.06 and 0.09 respectively. It provides a theoretical guidance for the establishment of the zero-dimensional approximation coupling model and the optimization of HSV.
    2015,31(18):34-40, DOI: 10.11975/j.issn.1002-6819.2015.18.006
    [Abstract] (16299) [HTML] (0) [PDF 8.13 M] (3070)
    Abstract:
    Abstract: In China, corn harvest gradually tends to mechanization, and corn threshing is the most important section in the process of corn harvest, which is directly affecting the damage level of corn seed. Manual threshing often chips away a row of corn ear with an awl firstly, and then it's easy to thresh other kernels. Based on this, some agricultural experts put forward a process of "pre-dispersion and post-threshing". Besides, the study found that after the long-term evolution, beak has not only excellent ability to insert into corn kernels, but also strong ability of dispersing kernels with low damage. To explore the movement law of corn ear kernels and low damage in the discrete process of corn ear, this paper had an experimental study on the beak to peck the corn kernel using the discrete test system with high-speed photography. The variety of experimental corn was Zhengdan 958 and the common domestic chicken was selected for testing. Self-made corn discrete test system was used in this experiment. The whole system consisted of mechanical data acquisition system and high-speed photography system. Due to the randomness of chicken pecking corn, firstly, the high-speed camera was fixed to the bracket, and then the best angle was selected to shoot at the beginning of discrete process. The shooting in the test was mainly from the ahead, the side and the back side of the test equipment with the shooting angle of 45°. The sensors were installed on the fixture to measure the forces in 3 directions respectively. Through observing the photos, we found that the closer the kernel was from beak, the larger the horizontal component of thrust was, the more obvious the movement was, and the easier kernel was to disperse from ear; on the contrary, the further the kernel was from beak, the smaller the horizontal component of thrust was, and the more difficult kernel was to disperse from ear. The kernels followed the "arrangement law" to deliver forces, whose range was approximate to a "tower", and the movement of kernel separated from corn ear was similar to oblique throwing movement. According to the data measured, the maximum force on the corn ear was in x direction, second in y direction, and the force in z direction was the minimum. The resultant force of x and y direction had a great influence on the number of the kernels separated from the corn ear. The results of verification test were that the average discrete rate was 67.53% and the damage rate was 0.16%, which showed that the beak had a significant effect on dispersing corn ear, and the damage rate was low. The study will provide a bionic thought on designing corn threshing system with low damage.
    2017,33(7):164-170, DOI: 10.11975/j.issn.1002-6819.2017.07.021
    [Abstract] (16092) [HTML] (0) [PDF 6.90 M] (3016)
    Abstract:
    Abstract: Planting area and spatial distribution information of crops are vital for guiding agricultural production, taking effective management measurements, and monitoring crop growth conditions. Numerous crop classification algorithms have been developed with rapid development of different remote sensing data. However, distinguishing of corn and soybean cropping areas still remains a difficult challenge due to their similar growth calendar and spectral characteristics. In this study, we tried to identify corn and soybean cropping area using random forest (RF) classifier which has been proved to be an effective method in land cover classification based on multi-temporal GF-1 WFV (wide field of view) imagery. We selected Nenjiang County, Heilongjiang Province in China as the study area which was called the Town of Soybean. Seven GF-1 WFV time-series images (April 14th, May 20th, June 26th, July 16th, August 26th, September 4th, and September 29th), from which the key growth stages could be extracted and the effects of clouds could be avoided, were chosen to classify main crops. First, we conducted atmospheric and geometric corrections on multi-temporal GF-1 imagery. In order to improve the accuracy of distinguishing corn and soybean cropping area, the parameters of RF classifier were input, which included normalized difference vegetation index (NDVI), wide dynamic range vegetation index (WDRVI), enhanced vegetation index (EVI), and normalized difference water index (NDWI), and hundreds of field sample points were collected in the field survey. Also, it’s necessary to evaluate the importance of different combination of these indices. The results showed that the combination of NDVI, WDRVI and NDWI achieved the best accuracy with the producer accuracy of 91.14% for soybean and 91.49% for corn, and with the user accuracy of 82.76% for soybean and 93.48% for corn. Then, the support vector machine (SVM) and maximum likelihood (ML) supervised classifiers were also used to map corn and soybean cropping areas; the classification results from the SVM and ML methods were compared with that from the RF approach with the Nenjiang Farm as the case study. The comparisons showed that the crop classification from the RF classifier had the higher accuracy than the others. Our results indicated that GF-1 data had particular advantages in mapping cropping area with its higher spatial and temporal resolutions, and could provide more effective remote sensing data during crop growth season. The temporal changes of main crops showed the best classifying date was September 29th when soybean has been harvested but corn hasn’t, and their vegetation indices showed the maximum difference. The multi-temporal imagery contributed to the separation of different spectral feature curves of different crops in the growth stages when crops had similar temporal variation profiles, which helped to decrease the omission and commission errors of the resultant mapping. The results also showed that the extracted spectral information of water and construction land was very different from vegetation and could be easily masked. Comparing the SVM and ML classifiers with RF classifier, the results suggested that RF classifier could successfully distinguish corn and soybean, and its overall accuracy reached up to 84.82%. This study provides important reference for crop mapping in other agricultural regions.
    2015,31(20):268-273, DOI: 10.11975/j.issn.1002-6819.2015.20.037
    [Abstract] (15969) [HTML] (0) [PDF 6.48 M] (3861)
    Abstract:
    Abstract: For detecting the quality of pork, traditional optical equipment has high accuracy, whereas heavy weight, large size and high price make it difficult to use widely. The purpose of this research was to develop a portable optical device for detecting pork quality based on visible/near infrared spectroscopy and embedded system. This paper mainly explained the models building and the development of application software. Firstly, a compact and flexible system was made. Halogen lamp is as light source. To adapt to various complex environments, its hand-held probe can form black room on the surface of pork. Micro spectrometer (USB4000) receives and measures reflected light. ARM (advanced RISC machines) processor controls all parts in device and analyzes spectrum data. Based on Linux embedded operation system, liquid crystal display (LCD) touch screen interfaces with users. The whole weight of 3.5 kg makes it convenient for users. Secondly, collect the spectrum reflected from pork samples and build the partial least squares regression (PLSR) model. Before these, spectrometer parameters should be set, so that it works under the best conditions. Integration time of USB4000 was set to 7 ms, pixel boxcar width zero. Thus the reflection intensity of standard white plate was about 80% of spectrometer scale span. During experiment, after acquiring white and black spectrum data, detection probe was put on the surface of pork samples. Spectrum data in the wavelength range from 400 to 1 000 nm were collected from the surfaces of 39 pork samples, 29 spectra of which were as calibration, while others as validation. The acquired spectrum data were then processed by standard normalized variables (SNV) and Savitzky-Golay filter (S-G) to eliminate the spectra noise. After collecting the spectrum data, reference pH values of pork samples were immediately tested by pH meter (METTLER TOLEDO FE20, Switzerland), and color parameters (L*, a*, b*) were measured by precision colorimeter (HP-200, Shanghai, China). The partial least squares regression (PLSR) was applied to establish the prediction models. Experiment results showed that prediction correlation coefficients of pH value, L*, a* and b* were 0.94, 0.98, 0.95 and 0.85, and standard deviations of pH value, L*, a* and b* were 0.17, 1.19, 0.42 and 0.61, respectively. Thirdly, application software was designed and developed for detecting the quality of pork. It consisted of spectrometer control unit, spectrum data acquisition unit, spectrum analysis unit, and displaying and saving unit for prediction result of pork quality. Particularly, in spectrometer control unit, all parameters of USB4000 were set as the same as those when building the PLSR models. The coefficients matrixes of models were loaded into pork quality detection software in spectrum analysis unit. After debugged, the application program detecting the quality of pork was cross-compiled, and downloaded into the device. Finally, the accuracy of models were tested. The reflect spectra of external 41 pork samples were collected and analyzed with the device. At the same time, the real values of these samples' pH, L*, a* and b* were measured. For the pH value, the prediction model could give satisfactory results with the correlation coefficient (Rv) of 0.88 and the standard error of prediction (SEP) of 0.19. For the color L*, a* and b*, the prediction models could gain prediction results with the Rv of 0.90, 0.97 and 0.97, and the SEP of 1.77, 1.17 and 0.63, respectively. In conclusion, the field application results indicate that this portable device can satisfy the requirements of meat quality detection with high accuracy and good performance.
    2014,30(8):257-264, DOI: 10.3969/j.issn.1002-6819.2014.08.030
    [Abstract] (15893) [HTML] (0) [PDF 4.73 M] (2743)
    Abstract:
    Abstract: During aqueous processing of peanuts for simultaneous oil extraction and protein recovery, large amounts of emulsion could be formed and after enzymatic demulsification, substantial amounts of oil would be recovered while stubborn emulsions still remain. The destabilization of the stubborn emulsion is the key to improve the total free oil yield. Before its utilization and further destabilization, studying the characterization of the stubborn emulsion, especially its surface protein, which may play an essential role in emulsion stabilization, was necessary. The surface protein was extracted and its electrophoresis property, hydrophobicity, emulsifying activity, as well as emulsifying stability were studied. Confocal laser scanning microscopy (CLSM) was used to investigate its microstructure. It was found that, though the protein from the emulsion surface had similar subunits (60, 41, 38.5, 37.5, and 18 kDa) with that from aqueous phase, its hydrophobicity and emulsion activity was significantly higher. This could be attributed to the synergistic effect of temperature and pH during the alkaline extraction, which led to the unfolding of some large peanut protein molecules containing hydrophobic basic arachins. This, consequently, caused the exposure of more hydrophobic groups and enhanced the hydrophobic and emulsifying properties of the protein. Thus emulsion formation was promoted. After enzymatic treatment, the protein in the emulsion was hydrolyzed into short peptides and no subunits with molecular weight higher than 20 kDa had been detected in Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). However, in non-reducing PAGE, except for the conarachin band of 60 kDa, protein from the stubborn emulsion surface showed similar bands with that from the emulsion surface and aqueous phase. This indicated that the hydrolyzed protein could still gather on the stubborn emulsion surface and contributed to its stability. Due to the hydrolysis of protein molecules, the hydrophobic property and emulsifying activity of protein from stubborn emulsion was lower than that from an untreated emulsion surface. CLSM observation showed that stubborn emulsion had less oil droplets and that their size was lower, while the surface protein concentration (Γ) was higher, as compared with untreated emulsion. This explained the high stability of stubborn emulsion, though its surface protein has lower surface activity. To demulsify the stubborn emulsion, various treatments, including ultrasound, freeze-thaw, heating, extreme pH value, phase inversion, or ethanol addition were attempted. Free oil was obtained after centrifugation and total free oil yield was calculated thereafter. The microstructure of the stubborn emulsion after different treatments was also observed with CLSM. Results show that freeze-thaw and ethanol addition could remarkably aggregate the oil droplets in stubborn emulsion, especially after 50% ethanol addition, most oil droplets were combined and 90% of the oil in stubborn emulsion could be recovered. Under this condition, the total free oil yield could be increased to 93% from 88% in the overall process.
    2016,32(8):278-284, DOI: 10.11975/j.issn.1002-6819.2016.08.039
    [Abstract] (15875) [HTML] (0) [PDF 1.43 M] (2514)
    Abstract:
    Abstract: At present, trawl fishing as a traditional method is widely used in shellfish harvesting at home and abroad. However, using this method to catch the scallops has many disadvantages, such as huge energy consumption, high labor intensity, and poor fishing efficiency, which have become the key questions to restrict the sustainable development of marine fishing industry. Therefore, it's very worth researching alternative scallop fishing equipment to meet the requirements of green development. The offshore scallop capture equipment is made up of platform deck, floating body and mooring, which is a kind of floating offshore engineering structure. This equipment occupies multiple functions, such as fishing, sorting, refining, storage and so on. Winch motors (ground net machine and anchor winch), cargo winch, generator unit, scallop separator, working cabin, accommodation and diesel generator were installed on the platform, and solar power as the source of power. In addition, to keep the scallops fresh and achieve the purpose of saving space, 2 shellfish purification storage networks were also set below the platform. Compared with the trawl fishing, it would substantially reduce energy consumption, realize precision fishing, raise fishing efficiency, and decrease the cost of purification. In this paper, based on the comparative methods, the technologic and economic parameters and the economic assessment indices were selected for the establishment of the technical and economic evaluation model, which was to investigate the economy of offshore scallops capture working platform. Firstly, the platform trawling engine power, the platform span, the hauls of platform anchored one time, the lateral movement time of platform anchored one time, the trawling speed of platform and the total construction cost of platform were selected as the technologic and economic parameters. Secondly, the capture fuel consumption per unit area, the unit cost of fishing and the capture efficiency were selected as the economic assessment indices. Next, the technical and economic evaluation model was established according to the technologic and economic parameters and the economic assessment indices. At last, based on this model, the economic calculation of fishing methods including fishing vessels and scallops capture working platform was carried out by using the comparative method. The results showed that when the platform trawling engine power was 400-470 kW, the platform span was 0.5-3.0 km, the lateral movement time of platform anchored one time was less than 2 h, the trawling speed of platform was beyond 1.4 kn, the total construction cost of platform was less than 27.5 million yuan, the scallops capture working platform project had more advantages over the fishing method of fishing vessels. Meanwhile, from these data, it was concluded that the haul of platform anchored one time was not very sensitive to the effect of scallops capture working platform project. The offshore scallops capture working platform conformed the policy of energy saving and emission reduction that was in line with the national "Twelfth Five-Year Plan". By further experimental verification, the analysis model and method can provide the economic theory reference for the fundamental changes in fisheries production mode in China.
    2016,32(12):107-114, DOI: 10.11975/j.issn.1002-6819.2016.12.016
    [Abstract] (15801) [HTML] (0) [PDF 413.47 K] (1784)
    Abstract:
    Abstract: Rapid population growth and economy development has led to increasing reliance on water resources. It is even aggravated for agricultural irrigation systems where more water is necessary to support the increasing population. In this study, an interval-parameter two-stage Fuzzy-stochastic optimization model was developed for dispatching the underground and surface water systems for different crops in Hong Xinglong irrigation of China under the conditions of uncertainty and complexity. In the model, the maximal system benefit was regarded as the objective function and 3 methods of probability density function, discrete intervals and fuzzy sets were introduced into the two-stage linear programming framework to resolve uncertain issues. The model allocated a predefined water to crops in the first stage, according to benefit and punishment for water shortage condition to adjust the water supply in the second stage, making the system reach the balance of systems benefit and the risk of punishment, the process of water allocation for multiple corps was simulated, meanwhile, the allocation of water from various sources was optimized. Because inflows water was of obvious probability characteristics in irrigation area, the model took into account of the random of inflow, and assumed that the probability of occurrence for high, middle and low levels were 0.2, 0.6 and 0.2. Since the quantity of stream flows, water requirement of crop and available water supply were uncertain, and uncertainties might also exist in system benefits and costs, the uncertain parameters of above-mentioned were described by interval variables. The available water in the irrigation area was represented by fuzzy sets based on credibility theory. The different probabilities, discrete interval number and fuzzy sets together were used to build the irrigation multi-water resource, multi-crop water distribution model. The model was solved by the method of linear programming, the optimal distribution scheme of water was achieved and the maximum benefit was 1 355.144×106-2 371.792×106 RMB. It could reflect not only uncertainties in water resources system, but also provide an effective linkage between conflicting economic benefits and the associated penalties attributed to the violation of the predefined water distribution target. Meanwhile, the results were presented in the forms of interval number, proving a more broad decision space for decision makers. Moreover, the results indicated that farmer planted a large number of high-yield and high water consumption of crops such as rice and corn in irrigation area and single planting structure would lead to the risk of the decrease of crop production in dry year, the model was valuable for supporting the adjustment or justification of the existing irrigation patterns and identify a desired water allocation plan for agricultural irrigation under uncertainty. Compared with the other traditional two-stage model, this model had advantages: 1) it considered uncertain factors as much as possible, made the model more close to actual condition; 2) The model effectively relieved groundwater pressure of water supply by utilizing surface water and groundwater; 3) The model results would suggest managers reducing planting area of high water consumption crops; 4) Water resources management by system benefit would stimulate employee enthusiasm; and 5) The model data was relatively easy to access.
    2016,32(5):120-125, DOI: 10.11975/j.issn.1002-6819.2016.05.017
    [Abstract] (15797) [HTML] (0) [PDF 3.29 M] (2219)
    Abstract:
    Abstract: Yanqi Basin is one of the most important oasis agricultural areas of Xinjiang. But the ecological environment of Yanqi Basin is fragile, which depends on groundwater resources greatly. To study the spatial-temporal evolution of total dissolved solids (TDS) of groundwater is of great significance to groundwater exploitation in arid areas with fragile ecological system seriously affected by human. In order to identify the groundwater pollution status in the plain area of Yanqi Basin, 42 groundwater samples was collected in 2014. TDS and concentration of anion and cationic of the 42 groundwater samples were tested. T test was used based on the observed data of groundwater in the different periods of the plain area to determine the variability of TDS. The relationships between TDS and macro anion, macro cation, pH were analyzed with SPSS software. The results showed that TDS of groundwater was mainly affected by SO42-, Cl-, K++Na+, Mg2+ and Ca2+. And the TDS were highly correlated with Cl- and K++Na+. The correlation between the TDS and macro anion was highest, followed by Cl-, SO42-and HCO3-; the correlation between the TDS and macro cation was also high, followed by K++Na+, Ca2+ and Mg2+. Zone map of TDS was drewn by the MAPGIS software. In the temporal scale, the average of TDS of groundwater was increased then decreased and increased again from 1983 to 2014, and the average value was 305.0, 1773.1 and 589.44 mg/L in 1983, 1999 and 2014, respectively. In the spatial scale, the TDS of groundwater evolved horizontally from piedmont to the plain area. The TDS of groundwater increased from upstream to downstream. Influenced by topography and hydrogeology conditions, the main hydrogeochemistry action changed from strong runoff to slow evaporation gradually. Area of groundwater with TDS<1 g/L showed an increasing trend but a decreasing trend from 1999 to 2014, which was consistent with downtrend of the mean value of TDS from 1999 to 2014 increased from 2011.7 to 2229.3 km2. There were 2 main reasons causing that change of groundwater TDS: 1) The groundwater table dropped from 4.98 to 7.34 m from 2000 to 2014, which prompted the solid phase calcium and magnesium soluble salts, insoluble salts and exchangeable calcium and magnesium in the soil and the lower layer sediments transferred to the groundwater; Meanwhile the increase of the groundwater table in the plain area led to high solutes concentration; 2) Urbanization had the great influence on the groundwater system. It changed the original land use patterns, and then the groundwater circulation system. And with the development of urbanization, industrial and domestic waste water increased year by year and could infiltrate into aquifer. The discharge of living and industrial waste water led to groundwater pollution, which was consistent with the dominant role of Cl- and SO42- in TDS. The study provide valuable information for understanding the condition of underground in Xinjiang.
    2017,33(12):66-73, DOI: 10.11975/j.issn.1002-6819.2017.12.009
    [Abstract] (15771) [HTML] (0) [PDF 5.69 M] (2800)
    Abstract:
    Abstract: The droplet quality of hydrodynamic ultrasonic atomization nozzle is better than the ordinary two-phase nozzle. And the atomization amount is larger than the piezoelectric atomization nozzle. High-quality droplet and high atomization amount are both required in the field of aeroponics. Therefore, it is necessary to develop a hydrodynamic ultrasonic atomizing nozzle suitable for large-scale aeroponics. Based on the basic principle of the Hartmann resonator, in this study, the mechanism of ultrasonic vibration of resonant cavity and the atomization mechanism of resonant cavity supersonic nozzle were analyzed theoretically. The Hartmann low-frequency ultrasonic atomization nozzle with stepped resonator and adjustable structural parameters was designed, including the Laval tube, the stepped tube, and conical shield. The influence of the structural parameters on the resonant state of the resonator was studied by means of CFD software transient numerical simulation. In order to make the spraying angle controllable, active flow control was used in the atomizing area, namely, adding a conical shield at the exit of the nozzle. The oscillation characteristics of the stepped resonance tube were further studied parametrically by numerical simulation methods. Numerical simulation of three kinds of atomizing nozzles including cylindrical tube, stepped tube and stepped tube with conical shield was carried out. The parameters which were studied were as follows: the distance between Laval outlet and inlet of stepped tube, depth ratio of the second stepped hole and the first stepped hole, conical cover, diameter ratio of the second stepped hole and the first stepped hole. Numerical simulation results showed that: (1) If the depth ratio of the stepped tube exceeded 2, its resonance frequency reached 1.6 to 1.7 times of the cylindrical one under the same working parameters; (2) The conical shield can make the pressure oscillation amplitude in the cavity bigger; and (3) The diameter ratio of the stepped resonator had a great influence on the resonant state of the resonator. The variation of diameter ratio of the stepped resonator changed the resonant mode of the stepped resonator from one mode to another. It also can make the resonance phenomenon disappear. As such, the key dimensions of the stepped resonator were determined accordingly. And an optimal diameter ratio was selected for trial production. And the optimal distance between Laval tube outlet and the resonant inlet 5.5 mm were selected as the initial structural parameter values of the spray test. The droplet size of three kinds of atomizing nozzles was tested and the test of droplet size was carried out with distance between Laval tube outlet and the resonant inlet, depth ratio of the second stepped hole and the first stepped hole, and other factors as variables. Moreover, its atomization properties were tested contrastively under different conditions. Research results showed that: (1) Start-up properties of oscillation can be optimized due to the main frequency unaffected by the conical shield;(2) The diameter ratio of stepped resonance tube was a quite sensitive parameter influencing the resonance state. The variation of diameter ratio can make the resonance mode change from 'jet regurgitant mode' to 'jet scream mode' or make the oscillation disappear; (3) Atomization properties of Hartmann atomization nozzle with a stepped resonance tube was better than those of Hartmann atomization nozzle with a cylindrical one; (4) If the air supply pressure was low, the droplet size was more sensitive with the pressure after adding a conical shield, while the gap of the average droplet size between the nozzle with stepped tube and that with traditional tube was not obvious under the condition of high air supply pressure. The distance between the Laval tube exit and the resonance tube was another sensitive parameter influencing the droplet size. An optimal distance, where the minimum droplet size can be acquired, was 6.5 mm. The droplet diameter increased gradually no matter the distance was bigger or smaller than the optimal distance. However, the droplet diameter varied slightly with the distance near the optimal point.
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    2009,25(8):288-293, DOI:
    [Abstract] (1681) [HTML] (0) [PDF 0.00 Byte] (117144)
    Abstract:
    In order to study the feasibility of microwave-assisted foam mat drying method for the dehydration blackcurrant pulp, a reasonable foaming additive formula was determined and the microwave-assisted foam mat drying characteristics of blackcurrant pulp were analyzed. The concentration of glyceryl monostearate (GMS) and soy protein isolated (SPI) with food grade, selected as the foaming additive, had obvious effects on the foaming properties of blackcurrant pulp. A reasonable foaming additive formula for the blackcurrant pulp with optimum expansion and high stability was developed that the 6% GMS and 3% g SPI as foam inducers and the 10 mL carboxylic methyl cellulose (CMC) with concentration of 0.5% as foam stabilizer, accompanying with the stirring time of 6 min. The experimental results of microwave assisted foam mat drying method showed that the drying intensity of foamed blackcurrant pulp increase with the increase of initial microwave intensity and the decrease of thickness of material layer. Contrasting the microwave with conventional hot air as the heat source for the foam mat drying of blackcurrant pulp, the qualities of dried blackcurrant product in terms of drying rate, color and appearance dried by microwave method are superior to that dried by the hot air. The parameters including the initial microwave intensity of 14.0 W/g and thickness of material layer of 5 mm are recommended for the continuous microwave belt dryer to dry the foamed blackcurrant pulp. Therefore, microwave assisted foam mat drying is suitable for the dehydration processing of blackcurrant pulp.
    2013,29(19):88-97, DOI: 10.3969/j.issn.1002-6819.2013.19.011
    [Abstract] (2182) [HTML] (0) [PDF 560.68 K] (39193)
    Abstract:
    Abstract: Aiming at the main problem that existed in estimating the crop water requirement through multiplying the crop coefficients of main crops determined in the early 1990s by ET0 calculated using the Penman-Monteith equation, the reasons for crop coefficients which need to be revised were analyzed. There is a significant difference in ET0 calculated by using the modified Penman equation and by Penman-Monteith equation, which affects overwintering crops with a longer growth period of greater than summer crops with a shorter growth period. The result showed that the monthly ET0 and ETrad calculated by using Penman-Monteith equation were higher than that by modified Penman equation, and the difference between radiation terms was the main reason that caused the difference between the calculation results by using two equations based on the meteorological data of 18 stations in Henan province. The difference of monthly ET0 and ETrad calculated by two equations in autumn and winter was higher than in spring and summer. The effect of aerodynamic term on ET0 was related to wind speed, and the reason that the effect of aerodynamic term on ET0 is higher than the radiation term maybe caused by high wind speed. Except for the relative humidity, average temperature and sunshine hours, radiation term was affected by the elevation of stations, as for the stations with a higher elevation, the impact of elevation on Penman-Monteith equation was greater than that on modified Penman equation. Using the sensitivity analysis method to evaluate the effect of average air temperature, relative humidity and sunshine hours on ETrad showed that Penman-Monteith equation was better than modified Penman model in calculating ETrad. The ETrad calculated through Penman-Monteith equation was little influenced by seasons and stations, and had a high stability. The results from 18 stations showed that the effect of average temperature on ETrad was the minimal, the impact of relative humidity in January, November and December on ETrad was larger, and the influence of sunshine hours from February to October on ETrad was also greater. Therefore, ET0 in Henan Province was calculated by Penman-Monteith equation instead of modified Penman equation, crop coefficients must be corrected, otherwise it caused the estimated values of crop water requirement to be higher, and its impact on overwintering crops with a longer growing period was greater than that on summer crops with a shorter growth period. Finally, according to the relationship between two difference methods of estimating ET0, the correction method of crop coefficient based on Penman-Monteith equation was proposed. This study has an important significance in improving the estimation precision of crop water requirement.
    2011,27(3):242-247, DOI:
    [Abstract] (2068) [HTML] (0) [PDF 0.00 Byte] (19547)
    Abstract:
    The technique for producing a kind of bio-degraded mulch from the straw fiber was studied. It is an alternative to plastic mulch with the same price and weed control, reducing evaporation functions. Rice straw fiber was the main material, and KP (wood fiber) as well as environment-friendly additives such as wet strength agent, rosin and bauxite were added. A central composite rotary orthogonal experimental design of RSM, with five factors and five levels for each factor was employed. Conventional paper producing technology was adopted, and pulp degree, mixture ratio, grammage, wet strength agent and conditioning agents were the input variables, dry tension strength, wet tension strength, sizing value were the response functions. The optimal technical parameters were obtained, the grammage value, conditioning agents content, wet strength agent content, mixture ratio and pulp degree were 90 g/m2, 0.2%, 0.8%, less than 68% and more than 45°SR respectively. Under the condition, dry tension strength of the sample mulch was higher than 30 N, the wet tension stress was higher than 10 N, and the sizing value was higher than 100 s. The sample of mulch made from rice straw fiber could meet the need of mechanical performance for laying field.
    2011,27(3):254-259, DOI:
    [Abstract] (2224) [HTML] (0) [PDF 0.00 Byte] (19320)
    Abstract:
    In order to study the related technology for preparing biodiesel by transesterification of cottonseed oil using solid based catalyst, with supported solid base Na3PO4/MgO as catalyst and biodiesel conversion rate as index, the optimum conditions for catalyst preparation were analyzed by single-factor and orthogonal experiments. The catalyst was characterized by methods of XRD, SEM and TG. Furthermore, the transesterification conditions from cottonseed oil to biodiesel were investigated using solid base catalyst. It was obtained that the optimum conditions for catalyst preparation were: 32% of Na3PO4 dosage on MgO, 600℃ of roasting temperature, 3 h of roasting time and 70℃ of blending temperature. Catalytic activity was related to Na3PO4 crystalline phase. The optimal conditions of transesterification with optimized catalyst were: 2.5 h of reaction time, 70℃ of reaction temperature, 15:1 of mass ratio of methanol to oil, 5% of quality ratio of catalyst to oil.
    2014,30(3):205-214, DOI: 10.3969/j.issn.1002-6819.2014.03.027
    [Abstract] (2483) [HTML] (0) [PDF 11.40 M] (16991)
    Abstract:
    Abstract: Rural residential areas are an extensive dispersion with localized concentrations, and the area of land utilization per capita is large in Dazhu village in Hechuan of Chongqing. Inefficient utilization of rural residential areas is an adverse process all over China during the urban-rural transitional period, especially in traditional agricultural areas. The space reconstruction of a rural residential area could be a breakthrough in the rational utilization of land resources, advancing new countryside construction, restructuring village space, and promoting urban-rural integration and development.This paper used the symbiotic theory to establish a rural residential restructuring symbiotic system. The system included rural residential areas as a symbiotic unit, and the policy environment and the village-domain environment as symbiotic environment. Due to the mutual functional differences of symbiotic units, village spatial reconstruction should consider a mutually beneficial symbiotic relationship between the units, namely the mutualism mode. The research analyzed a rural residential restructuring symbiotic system, and made clear the restructuring principles and procedure needed to build the space reconstruction strategy of a rural settlement. The thesis selected the demonstration village of the whole village advancement-Dazhu village in Hechuan of Chongqing as the object of empirical study. It built three kinds of functional groups-productivity-oriented, service-oriented, and living-oriented groups, a space representation of which was already presented in the village, and formed the layout of 'one axis and three groups' at the the village scale.The results showed that: first, adopting the rural residential restructuring symbiotic system analysis accords with the reality of Dazhu village to restructure village space. It further showed that the symbiotic theory has strong applicability to space reconstruction of a rural settlement. Secondly, the results of the empirical study showed that the space reconstruction of a rural settlement, which is based on the symbiotic strategy, can both ensure the inter-operability of a rural settlement and respect the principal position of farmers. It realizes 'shared resources, co-constructed environment' and exploits environmental advantages in the village domain. It can also improve the utilization efficiency of rural residential areas. Through the study of the demonstration village, the paper provides a scientific basis for formulating village space reconstruction and a new approach to the whole village advancement in a hilly area and the beautiful village construction. Due to the fact that the factors which influence rural residential restructuring are very complex, the regional social, economic, and environmental development strategies and resource endowment conditions which are expected to be considered comprehensively, need to be studied further. Different types of household willingness and future livelihoods also require deeper study.
    2021,37(16):127-135, DOI: 10.11975/j.issn.1002-6819.2021.16.016
    [Abstract] (374) [HTML] (0) [PDF 22.64 M] (15569)
    Abstract:
    Abstract: Automatic fruit recognition is one of the most important steps in fruit picking robots. In this study, a novel fruit recognition was proposed using improved YOLOv3, in order to identify the fruit quickly and accurately for the picking robot in the complex environment of the orchard (different light, occlusion, adhesion, large field of view, bagging, whether the fruit was mature or not). The specific procedure was as follows. 1) 4000 Apple images were captured under the complex environment via the orchard shooting and Internet collection. After labeling with LabelImg software, 3200 images were randomly selected as training set, 400 as verification set, and 400 as a test set. Mosaic data enhancement was also embedded in the model to improve the input images for the better generalization ability and robustness of model. 2) The network model was also improved. First, the residual module in the DarkNet53 network was combined with the CSPNet to reduce the amount of network calculation, while maintaining the detection accuracy. Second, the SPP module was added to the detection network of the original YOLOv3 model, further to fuse the global and local characteristics of fruits, in order to enhance the recall rate of model to the minimal fruit target. Third, a soft NMS was used to replace the traditional for better recognition ability of model, particularly for the overlapping fruits. Forth, the joint loss function using Focal and CIoU Loss was used to optimize the model for higher accuracy of recognition. 3) The model was finally trained in the deep learning environment of a server, thereby analyzing the training process after the dataset production and network construction. Optimal weights and parameters were achieved, according to the loss curve and various performance indexes of verification set. The results showed that the best performance was achieved, when training to the 109th epoch, where the obtained weight in this round was taken as the final model weight, precision was 94.1%, recall was 90.6%, F1 was 92.3%, mean average precision was 96.1%. Then, the test set is used to test the optimal model. The experimental results show that the Mean Average Precision value reached 96.3%, which is higher than 92.5% of the original model; F1 value reached 91.8%, higher than 88.0% of the original model; The average detection speed of video stream under GPU is 27.8 frame/s, which is higher than 22.2 frame/s of the original model. Furthermore, it was found that the best comprehensive performance was achieved to verify the effectiveness of the improvement compared with four advanced detection of Faster RCNN, RetinaNet, YOLOv5 and CenterNet. A comparison experiment was conducted under different fruit numbers and various lighting environments, further to verify the effectiveness and feasibility of the improved model. Correspondingly, the detection performance of model was significantly better for small target apples and severely occluded overlapping apples, compared with the improved YOLOv3 model, indicating the high effectiveness. In addition, the target detection using deep learning was robust to illumination, where the illumination change presented little impact on the detection performance. Consequently, the excellent detection, robustness and real-time performance can widely be expected to serve as an important support for accurate fruit recognition in complex environment.
    2020,36(11):39-48, DOI: 10.11975/j.issn.1002-6819.2020.11.005
    [Abstract] (801) [HTML] (0) [PDF 8.24 M] (15350)
    Abstract:
    Abstract: Accroding to literatures and preliminary tests, the structure of cheaning device of longtitudinal axial flow grain combine harvester had a significant impact on wind speed distribution of upper sieve surface and cleaning effects of the device. In this paper, the RG60 type single longitudinal axial flow grain combine harvester developed by LOVOL Heavy Industry Co. Ltd. was tested in Xichang, Si Chuan Province. In order to analyze the wind speed distribution on the upper sieve surface, 45 measuring points were set up, the measurement results showed that the wind speed on upper sieve surface was uneven, the speed at front air outlet of fan installation, forth and fifth column from left of tail sieve were greater than else, the maximum wind speed was 8.6 m/s which was smaller than floating speed of grain, the wind speed on sieves of 3 and 4 row, 6 and 7 row was 5.8 and 5.9 m/s respectively, the speed on middle sieve surface was the smallest. The wind speed on the right side was greater than that of the left side. In the middle and right of upper sieve surface, there was less accumulation of grain mixture, while there was more accumulation in the left, the distribution of grain mixture was uneven which was not conducive to separation of grain and impurities. In order to solve the problem that wind speed distribution was uneven on upper sieve surface, the force and speed of grain mixture in cleaning device were analyzed. According to the structure of cleaning device, because the right side of centrifugal fan was equipped with power input pulley so the air inlet resistance value was higher than left side, and the dynamic pressure was smaller. In addition, the large transverse width of vibrating sieve lead to uneven distribution of wind speed on upper sieve surface, resulting in more grain mixture on left side of tail sieve. In order to further analyze tje distribution of wind speed in cleaing device and optimize its structure, the simulation was carried out in Hyper Works. The results of wind speed on upper sieve showed that the test results of wind speed change trend of each measuring point were consistent with the simulation results, with an average deviation of 0.293 m/s, which indicated that the simulation can reflect wind speed distribution of the internal flow field of cleaning device. The maximum wind speed at the front of upper sieve surface was 10.024 m/s, the left side in lateral wind speed of upper sieve surface in cleaning area was much smaller than that of the right side. The maximum wind speed at the rear of upper sieve surface was about 8.02 m/s which was less than that of the suspension speed of materials. The wind speed in middle of tail sieve was high which was bad for separation of grain mixture. The wind speed of fourth column from left on front air outlet was 8.184 m/s while it at third column from left and middle of tail sieve was 8.411 m/s, and the speed on sieves of 6 and 7 row, 8 and 9 row were the smallest, this trendy was same as the test results. In longitudinal section X=650 mm of upper sieve surface, the wind direction was gradually to right in the process of blowing to upper sieve surface, and the maximum wind speed is 17.077 m/s. In cross section Z=-450 mm, the range of wind speed was from 6.5 to 10 m/s, the turbulence in wind field in middle of upper sieve surface may result in less effect separation of grain mixture. The reason for this phenomenon was the right side of centrifugal fan was equipped with a power input pulley, which made the direction of air flow generated by fan deviate. Therefore, the structure of cleaning device was improved to eliminate this phenomenon. The simulation experiment was carried out when the wind shield rotated 10°, 20°, 30°, 40° and 50° counterclockwise, respectively. The results of optimization simulation showed that internal flow field was evenly distributed when wind shield rotated 30° counterclockwise. the wind speed of upper sieve left side gradually decreased while right side gradually increased with increase of counterclockwise rotation angle of wind shield, the wind speed in middle of tail sieve was the highest which was within the range of [8.231, 10.289] m/s, about 2 m/s higher than that before the improvement, the phenomenon of uneven distribution of wind speed on sieve surface and large difference on left and right sides was improved. The optimized harvester test results showed that third column from left in front air outlet and sieves of 11 and 12 row, the wind speed increased by 1.9 and 2.8 m/s respectively, and its distribution at left and right sides of rear of tail sieve was the most uniform. the wind speed in middle of front air outlet on upper sieve (third column from left) was the maximum as 8.7 m/s, it in sieves 11 and 12 row was 6.3 m/s, the lowest was 5.0 m/s in tail sieve. The wind speed along left side and right side of upper sieve surface were gradually decreased, and the overall wind speed distribution was uniform The loss rate of wheat and the impurity rate was 0.89% and 0.37% respectively, the loss rate of rice and impurity was 1.85% and 0.51% respectively, the cleaning performance and uniformity of the wind flow field distribution of the cleaning decice was improved. The research results provide a reference for the design and parameter optimization of the cleaning device of single longitudinal axial flow harvester.
    2021,37(1):223-232, DOI: 10.11975/j.issn.1002-6819.2021.01.027
    [Abstract] (1258) [HTML] (0) [PDF 6.54 M] (14332)
    Abstract:
    An improved Convolutional Neural Network (CNN) was proposed to solve the time-consuming and inefficient detection for the surface defect on the Hami melon in recent years. The Hami melons were purchased from 103 Regiment, 6th Agricultural Division, the Xinjiang Production and Construction Corps, China. A total of 200 images of normal Hami melons were taken by a camera in a black box. 100 images of Hami melons were collected with the various surface defects, such as mildew, sunburn and crack. Since it is difficult to collect samples with three defect types, the data enhancement technique was used to expand the dataset. A total of 10 000 sample images were obtained, and then divided into a training and test dataset, according to the proportion of 4:1. A VGG-like model was improved by adding a convolutional layer and a pooling layer at the beginning. As such, the improved VGG-like model included three convolutional layers, three max-pooling layers, a flatten layer, and two fully-connected layers. The softmax classifier was used in the last fully-connected layer. The Rectified Linear Unit (ReLU) function was chosen as the activation function. The Stochastic Gradient Descent (SGD) was chosen as the optimizer. The improved VGG-like model was used to identify four-class defect samples. The optimal hyperparameters in the CNN models were determined via the performance under the different learning rates and epochs. In all established CNN models, the test data showed that the AlexNet model outperformed other VGG-16 models, with the learning rate of 0.001 and the epochs of 500. Moreover, the AlexNet model can achieve the best performance with the accuracy of 99.69% and 96.62% in the training and test dataset, respectively. Three image processing techniques were compared to evaluate the preprocessing impact, including the Principal Components Analysis (PCA), Singular Value Decomposition (SVD), and binarization. The results indicated that the preprocessing provided a better detection performance on the various surface features of Hami melon in image preprocessing. The improved VGG-like model was the optimal to detect four-class defect on the Hami melon surface, indicating the learning rate of 0.001 and the epochs of 500. The prediction accuracy of improved VGG-like model in test set reached 97.14%. A visualization technique was used to analyze the features of convolutional layers, particularly on feature extraction in a CNN model. The visualization results showed that the defect features became more and more obvious with the increase of the convolutional layers. The defect features were the clearest in the captured images by the last convolutional layer. In addition, the convolutional features with the input as the preprocessing images were clearer than before. Finally, the improved VGG-like model was verified by the developed software on the plateform of PyQt5. The developed software functions included Open Camera, Read Image, Image Processing (Gray, PCA, SVD and Binarization), and Image Identification. The detection time of a single image was less than 0.7 s. In each type, 50 images were captured under the same environment. A total of 200 test images were collected. The test results showed that none of normal samples was predicted as defect samples. Only 8 crack Hami melons was incorrectly identified, due mainly to the unobvious feature. The average prediction accuracy of 200 samples was 93.5%. The improved VGG-like model with the preprocessing can be expected to apply for the detection of defects on the Hami melon surface, and other on-line nondestructive detection in the future.
    2013,29(23):268-275, DOI: 10.3969/j.issn.1002-6819.2013.23.037
    [Abstract] (1485) [HTML] (0) [PDF 1.94 M] (13716)
    Abstract:
    Abstract: Clarity of juice is an important factor regarding the quality of the juice as it fetches consumer attention for the product in the market. Clarification is a key step in the processing of fruit juice and is most often achieved through micro filtration, enzymatic treatment, or by using common clarifying aids like chitosan, gelatin, bentonite, silica sol, polyvinyl pyrrolidine, or a combination of these compounds. Chitosan (poly-b(1-4)N-acetyl-glucosamine) being poly-cationic in nature, nontoxic, and biodegradable, has been found to be an effective coagulating agent in aiding the removing pectin and other carbohydrates which are present in the juice. The clarification of ponkan juice by means of chitosan was studied in this paper. In order to obtain the optimal reaction conditions of clarification of ponkan juice by commercially inexpensive chitosan, the process conditions of clarification with chitosan on ponkan juice were optimized by a Box-Behnken center-united experiment design. Taking juice clarification as a dependent variable, the models were obtained by using a response surface analysis of the three factors of chitosan concentration, chitosan treated temperature, and the chitosan treated time based on a single factor experiments. The results indicated that the interaction effect of chitosan concentration and chitosan treated temperature, chitosan concentration, and chitosan treated time on the juice clarification achieved a very significant level. The influencing factors had a complicated relationship with each other. Among these factors, chitosan treated time、chitosan concentration, and the chitosan treated temperature ranked in order. The results from the Box-Behnken center-united experiment showed that the optimum technological condition for clarification of ponkan juice was adding 0.8 g/L chitosan at 59°C for 71 min and its clarification of the ponkan juice was up to 97.8%. The experiment indicated that there was a good fit between the predicted and the experimental values. The mathematical model was also very accurate. Comparing with the original ponkan juice, the contents of soluble solids, vitamin C, and titratable acidity were almost the same after clarification. Removing the pectin, total phenolics, and proteins improved the non-biological stability of the ponkan juice, because of the phenomenon of flocculating with chitosan. According to the non-biological stability tests, the results of stability tests of protein, potassium hydrogen tartaric acid, iron, copper, and oxidation showed negative, and indicated that the non-biological stability of ponkan juice were strengthened by chitosan to a certain extent.This article could provide a theoretical basis for clarifying ponkan juice in manufacture. According to the optimal technological condition of the experiment, clarification of 1 L juice only costs 0.15 yuan. The popularization and application of this technology will bring great economic benefits for the industrial production of juice.
    2021,37(1):213-222, DOI: 10.11975/j.issn.1002-6819.2021.01.026
    [Abstract] (1100) [HTML] (0) [PDF 4.66 M] (12260)
    Abstract:
    Ginger is widely cultivated in temperate zone, tropical and subtropics. China is the largest ginger producer and exporter in the world. Sowing seeds can be the second step in the ginger production, after the soil preparation is ready. It is necessary to lay the ginger flat in the trench, and keep the shoots in the same direction when sowing, in order to ensure that the shoots can emerge in the same direction under the requirement of avoiding light in the production. All the shoots emerge towards the south in an east-west trench, whereas those towards the west in a north-south trench. Therefore, shoots recognition has become a type of key technology to ensure the same direction of shoots, and then realize automatic and accurate sowing. In this study, a feasible way was proposed to realize the rapid recognition and accurate determination of ginger shoots using deep learning. Firstly, the dataset of ginger images was established, including image acquisition, enhancement, and labeling. Secondly, in training a small sample dataset, the data was augmented using online data enhancement to increase the diversity of images, and address the lack of generalization capability. The Mosaic method was used to enrich the background of ginger shoots training without introducing non-informative pixels. Thirdly, the position of ginger shoots regression bounding box directly determined the specific position of shoots, thus DioU (Distance Intersection over Union) bounding box regression loss function was introduced instead of the traditional loss function of IOU, in order to improve the regression effect of regression bounding box. Fourthly, in order to improve the convergence rate of model, the K-means clustering using the IoU measurement was used to derive 9 anchor boxes after linear scaling, indicating more in line with the shoots size. In addition, the Darknet-53 model pre-trained on the ImageNet data set was used for transfer learning, aiming to reduce the training time of model. Finally, after the identification of shoots were completed using the YOLO v3 network, in order to facilitate the selection of the strongest shoot, the area of the prediction bounding box was used as the basis for selection, and only the prediction bounding box with a larger area was retained. A Cartesian coordinate system was established with the center of the image as the origin, and the orientation of shoots was discriminated by calculating the azimuth of the center of prediction bounding box. The average precision and F1 were used to evaluate the performance of ginger shoots recognition model. In test, the IoU threshold and the confidence threshold were analyzed to obtain the best detection effect, while the improved strategies were verified one by one. After training and testing, the detection index was the best, when the IoU threshold was 0.6, and the confidence threshold was 0.001. The average precision and F1 measure reached 98.2% and 94.9% in the shoot recognition model, respectively, where the detection speed was 112 frames/s for a single 416×416 pixels image on the GPU. Compared with the original YOLOv3, the average precision and F1 measure increased by 1.5% and 4.4%, respectively. The recognition model of ginger shoots can be used to achieve significantly excellent recognition, providing a sound theoretical basis to realize automatic and precise ginger sowing.
    2019,35(23):135-141, DOI: 10.11975/j.issn.1002-6819.2019.23.017
    [Abstract] (582) [HTML] (0) [PDF 1.77 M] (11874)
    Abstract:
    The Loess Plateau in China is one of the most severely eroded regions of the world. Since the implementation of "Grain for Green" ecological restoration project, biological soil crusts (biocrusts) were widely distributed in this region, which significantly affected surface runoff. Numerous studies have explored the effect of biocrusts on runoff. However, the conclusions were still widely different. In the Loess Plateau region, rainfall is mostly concentrated in June to September, and the rainfall duration is not fixed, which may affect the runoff characteristics of biocrustal slopes. This study investigated characteristics of runoff from biocrustal slope in different rainfall durations in the Loess Plateau region by using artificial simulated rainfall experiment. The experiment was conducted in the revegetated grassland of northern Shaanxi Provence, China. The experiment site was about 80 m×20 m, and the slope gradient was approximately 15°. The biocrust types were mainly moss crust and moss cyanobacteria mixed crust in this site and their average coverage was 79.2%. The dimensions of the experimental plots were 10 m×2.1 m (length×width).Canopy of higher plants in the plots was removed with scissors. According to the range of local biocrust coverage, two treatments were set: 1) slopes with undisturbed biocrust as a high coverage biocrust (the average biocrust coverage were 79.2%); 2) the slopes with removal of a part of the biocrusts by shovels, which simulated the low biocrust cover situation (the average biocrust coverage were 43.6%). Meanwhile, ploughing plots were set as the control group. The rainfall intensity was set as 90mm/h and the duration was1 hour. The results showed that the initial runoff time of biocrust slope was significantly reduced compared to the bare soil slope. The initial runoff yield time of bare soil was 1.59-3.04 times that of the biocrust slopes. There was a significant negative correlation between biocrust coverage and initial runoff generation time; Conclusion of the influence of biocrusts on runoff yield was contradictory during the first 15 min and 60 min. For 90 mm/h rainfall intensity, runoff from biocrust slope increased by 75.42% compared to bare soil when the rainfall duration was the 15 min. While, runoff from biocrust slope was decreased by 52.42% compared to the bare soil when the rainfall lasted to 60 min; the infiltration rate of soil moisture was affected by biocrusts. The infiltration rate of bare soil slope with 60 min rainfall was 34.30% lower than that with 15 min. The infiltration rate of high coverage biocrust slope with 60 min rainfall was only 6.38% lower than that with 15 min, which may cause the difference of runoff yield between bare soil slope and biocrust slope; the effect of biocrust on slope infiltration and runoff is closely related to rainfall duration. Different periods of rainfall are likely to lead to inconsistent conclusions. Therefore, the duration of rainfall experiment considering the factors of biocrust should be no less than 45 min. The study provides scientific evidences for explaining the differences in the effect of biocrusts on infiltration and runoff, and further clarifies the hydrological effect of biocrusts in arid and semi-arid areas.
    2016,32(17):127-135, DOI: 10.11975/j.issn.1002-6819.2016.17.018
    [Abstract] (3358) [HTML] (0) [PDF 15.27 M] (11678)
    Abstract:
    Abstract: Remote sensing technology is a major method to obtain spatial distribution and quantity of winter wheat area, and classification method suitable for business operation is a key technology target of annual winter wheat remote sensing monitoring. Aimed at the conditions and demands of winter wheat background survey business operation in agriculture information service, this paper has proposed a weighted NDVI index (WWAI) based on normal difference vegetation index (NDVI) time sequence. By taking the extraction of 2013-2014 winter wheat area of Anping County, Hebei Province as an example, the algorithm is realized by using GF-1/WFV (wide field view) data. The main idea of the algorithm is to amplify the difference between winter wheat land type and other ground object types by establishing a winter wheat area index based on time sequence images, and to differentiate winter wheat land type from the others and thus to obtain the crop area of winter wheat by automated threshold value setting method. The algorithm includes the following 5 parts: acquisition of winter wheat time sequence images, sample points setting based on grid, establishment of winter wheat area index, identifying winter wheat area index estimation threshold value by iteration, and accuracy validation. Acquisition of images is based on the identification of growth time of winter wheat, and the principle is to ensure to get one GF-1/WFV cloudless image each month. Growth period of winter wheat in Anping County is from October 1st to June 30th of the next year, including 9 growing stages, i.e. seeding, germinating, tillering, overwintering, reviving, jointing, head sprouting, milking maturity and maturity. One GF-1/WFV cloudless image is selected in the middle 10 days of each month, and a total of 9 images are selected for pre-processing and NDVI calculation. Meanwhile, the study area is divided into a certain number of grids, and each grid is further divided into 2×2 sub-grids. The ground object types of central points in upper left and lower right grid are identified by visual interpretation, expert knowledge and field investigation. In this paper, a total of 10×10 equal interval grids with the average grid size of 4.1 km × 4.0 km, as well as 400 sub-grids with the size of 2.05 km × 2.0 km are obtained. The average NDVI values of winter wheat and other ground objects on all upper left centers of this period are calculated. If the winter wheat NDVI is higher than that of other ground objects, the weight of the images of the period is set to 1, and otherwise, set to -1. The winter wheat area index images can be obtained by using the weighted average of NDVI images of all time phases. After obtaining winter wheat area index, it is also necessary to set appropriate threshold value for winter wheat area extraction. The paper takes the visual interpretation classification results of lower right grid points as the basis for threshold value extraction. The specific method is to divide winter wheat area index from small to large with certain intervals, and then to make dimidiate extraction of winter wheat area indices of the lower right centers by taking each divided value as the extraction threshold value. By comparing with the visual interpretation result, the result with the highest accuracy is taken as the optimal winter wheat area index extraction threshold value, which is identified to be approximately 1 600 with self-adaptation approach finally. In all grids, accuracy validation is conducted by taking the 10 plots with equal probability. Accuracy validation results show that the overall classification accuracy has reached 94.4%, with Kappa coefficient of 0.88. The area extraction accuracy of this method is about 1.7% higher than that of conventional method based on NDVI time sequence images. By establishing winter wheat area index, this paper turns a complicated multiple-parameter problem into a single-parameter problem with clearly defined agricultural significance. This method is featured with high automatic degree and stable classification results, and it has been widely applied in the crop area remote sensing monitoring practices in China.
    2008,24(8):232-235, DOI:
    [Abstract] (9217) [HTML] (0) [PDF 0.00 Byte] (10736)
    Abstract:
    The adsorption-desorption characteristics of phosphate by five common substrates (savageness Zeolite, Haydite, Soil, Vermiculite and Gravel) used in soil treatment systems were illustrated in laboratory. The results indicate that phosphorus adsorption capacities of various substrates in the descending order are vermiculite and soil(1.38 mg/g and 1.24 mg/g), then haydite and zeolite(1.12 mg/g and 1.18 mg/g), and then gravel(0.90 mg/g). The five substrates all reach adsorption equilibrium after twelve hours’ shaking time, and the adsorption capacity increases as the original phosphorus concentration in the liquid increases. The results indicate that phosphorus desorption efficiencies of various substrates in the descending order are gravel, soil, zeolite, vermiculite and haydite. Considering the phosphorus adsorption capacities and desorption rates of five substrates in the research, vermiculite is one sound substrate in the soil treatment system for phosphorus removal.
    2015,31(z1):237-246, DOI: 10.3969/j.issn.1002-6819.2015.z1.028
    [Abstract] (2771) [HTML] (0) [PDF 10.15 M] (10593)
    Abstract:
    Abstract: The Internet of Things (IoT) technology, based on the perception, is developing rapidly and permeating into every walk of life. IoT of agriculture, including animal husbandry, has been showing a status of rapid development and is urgent in keeping pace with other industries. In this study, livestock coding specification and identification technology, remote monitoring technology of livestock farm environments and animal behaviors, and precise sow feeding equipment and digital network management platform of farms were reviewed to expound the application effects and limitations of IoT in animal husbandry. We found that at the perceptual layer, the international standards for livestock identification mainly included the ISO TC 23/SC 19, which set rules for radio frequency identification (RFID) for livestock management, and it was functionally divided into ISO 11784, ISO 11785 and ISO 14223. The Chinese standards for livestock identification were described in three levels: national standard specifications, local standards, and corporate standards. For example, the three different standards are Ministry of Agriculture Legislation No.67, local standard of identification in Shanghai (DB31/T341-2005), and Xinjiang (DB 65/ T3209-2011), and internal encoding specification of Beidahuang Agriculture Co., Ltd and Yiliyuan Co., Ltd. At the transport layer, the environment parameters of livestock farms like temperature, humidity, illumination intensity, ammonia concentration, and carbon dioxide concentration etc., and animal behavior parameters like body weight and body temperature would be perceived by different sensors and then the data from environment parameters and individual animal behavior data mentioned above would be remotely transferred through a wireless public network (2G/3G/4G). The video data and huge production process data were transferred into internet network databases by wired networks. At the data application layer, the typical application examples were shown below. Firstly, remote monitoring, data collection, and transmission of breeding environment parameters or animal production data were realized by using an intellectual mobile terminal to analyze and give early warning of the collected data. Then, the system will selectively turn on or off the remote intelligent environmental control equipment (draught fan, light, heater, and water pump etc.) based on the analysis results. The second example was the construction of a cloud-computing platform of cow-breeding farms and pig-breeding farms-that is, production data of hundreds or thousands farms were collected by network databases and data was cloud-stored as well as cloud-analyzed in the form of formal meta data, and the platform would give farmers warning information based on the analysis of production and breeding database by data mining technology. The third example was the development and application of automatic electro-mechanical feeding control systems of lactating sows, which was composed of electro-mechanical systems, wireless network technology, mobile SQL Lite network database, electronic data interchange, and feed intake prediction models of lactating sow nutrient requirements. This paper also analyzed the deficiencies of animal husbandry's IoT in technology, product, application, related policies, and people's cognitive from microcosmic to macrocosmic aspects, and suggestions were given based on the above deficiencies. Above all, the modernization development of animal husbandry needs the support of the IoT and IoT in turn is urged to accumulate its positive energy and promote itself better through applications in the different technological fields.
    2020,36(23):171-180, DOI: 10.11975/j.issn.1002-6819.2020.23.020
    [Abstract] (546) [HTML] (0) [PDF 3.89 M] (9472)
    Abstract:
    Aiming at the problems of low efficiency of manual grading and inaccurate mechanical grading of peanut pods, a convolutional neural network peanut pod grades image recognition method based on transfer learning was proposed. By using the operations of the flip, rotation, translation, contrast transformation, and brightness transformation, the obtained five grades (first-grade pod, second-grade pod, third-grade pod, fourth-grade abnormal pod, and fifth-grade damaged pod) of peanut pod images were expanded and preprocessed, thus the peanut pod grades image data set was established. The 60% of data was randomly selected as the training set, 20% of data was randomly selected as the validation set, and the remaining 20% as the test set. The performance of peanut pod image classification based on the GoogLeNet, ResNet18, and AlexNet was compared and analyzed. The peanut pod grades recognition model was improved by transferring the AlexNet convolution layers. The local response normalization was replaced by batch normalization, and the activation function was placed in different positions before and after the batch normalization layer, so that four different recognition-training models were designed, including the PA-I model, PA-II model, PA-III model, and PA-IV model. The transfer learning contrast experiments and the hyperparameter optimization experiments of the learning rate carried out for the four improved AlexNet models proposed above. The effects of the unsaturated activation function (ReLU) and improved unsaturated activation function (LReLU) on the performance of the model were studied. The experimental results showed that the training time of the AlexNet model was the least on the basis of satisfying the test accuracy and the learning rate of transfer learning based on the improved AlexNet model was a very important hyperparameter that needed to be optimized. If the learning rate is chosen too high, the model training oscillates seriously and even can’t train normally; if the learning rate too small, the model training slow. An appropriate learning rate can speed up the training and improve the recognition ability of the model. When the learning rate was updated automatically, the model with batch normalization had better performance than local response normalization, which could make the model get higher accuracy and lower loss value. When the coefficient of activation function LReLU was 0.000 1, the performance of the LReLU used in the model was equivalent to that of the ReLU used in the model, therefore LReLU had no substantial impact on the training results of the model. The addition of batch normalization and reduction of parameters in the model reduced 220 s training time and improved the model’s performance. The classification accuracy of the proposed peanut pod grades recognition model for the first-grade pod, second-grade pod, third-grade pod, fourth-grade abnormal pod, and fifth-grade damaged pod was 93.57%, 97.14%, 99.29%, 87.14%, and 100% respectively and the average classification accuracy reached 95.43%, and F1-scores achieved 96.32%, 97.49%, 99.64%, 92.42%, and 94.50% respectively. The model proposed in this study had high classification accuracy for peanut pod grades and could provide a reference for the precise classification of other agricultural products.
    2006,22(2):127-131, DOI:
    Abstract:
    By analyzing the problems of traditional methods for estimating the weight of pigs, the authors discuss a new method which applies computer vision technology to pig production. The projected image area of pigs when viewed directly from above was computed. The pig weights were estimated by the linear regression of the pig real areas. The results show that a strong relationship exists between pig weight and the projected area of the pig after removing the sections of head and tail in images. The correlation coefficient is 0.94. By comparing with the measured weights, the relative error is less than 2.8%. The experiment indicates that this hands-off method has great significance in scientific management of the pigs, which does not require large labor and material resources, and also avoid the loss in production resulted from stress.
    [Abstract] (2606) [HTML] (0) [PDF 2.10 M] (9174)
    Abstract:
    Abstract: In the northern and especially northeastern areas of China, it is so quite pleasantly cool and dry in the autumn that farmers used to cure peanuts in the field for some days after digging in order to decrease the mass of the peanut plants, and more easily transport and pick up the crop. It indicated that the two-stage harvest might be more suitable to peanut production in the north and northeast areas of China. Based on the viewpoint and theory of combining machinery with agronomy, the main peanut varieties in the western of Liaoning were selected as test materials, the variances of moisture content, and mechanical properties of peanut stems and pegs accompanying the change of curing days were studied by means of an infrared moisture meter and a universal bio-material testing machine. During the test, the curing days of peanut plants in the field after digging was selected as the basic variable, and more than seven days as the time span. The moisture contents of peanut stem and peg, and the tensile strength of the peg and its nodes were measured. The change rules of moisture content of peanut plants during the curing process in the field were obtained, which showed that the change rules of three kinds of peanuts were very similar i.e. the moisture content of the peanut stem and peg dropped rapidly with the extension of curing time in the early drying time (previous two days), and then the moisture content decreased slowly. The change rules of moisture content of peanut plants change tended to be an asymptote from the third curing day, when the moisture contents of the peanut stem and peg were almost no longer dropping, and finally settled around 9%. The moisture content of the peanut peg and its two nodes ranged from 8.48% to 65.68%, and the changes of tensile strength and moisture content in the three kinds of peanuts were quite similar. In the whole curing process, the tensile strength of the peanut peg was always highest, the tensile strength of the peanut-peg node was lowest, and the tensile strength of the stem-peg node was in the middle. The tensile strength of the three key positions of the peg all changed with the moisture content. And the tensile strength of the fresh peanut plants with high moisture content were highest, the tensile strength of peanut peg and its two nodes decreased rapidly in the early curing time, and then dropped slowed until it gradually tended to a constant value. The regression equation of the tensile strength and the moisture content of the peg and its two nodes as obtained by the method of SPSS software were that the fitting coefficient of stem-peg node tensile strength was 0.9891, the fitting coefficient of peanut-peg node tensile strength was 0.9974, and the fitting coefficient of peanut peg tensile strength was 0.9966. And under the experimental condition, the optimal curing days before picking up was preliminarily determined to be 3~5d, and the corresponding moisture content of the peanut peg ranged from 10% to 20%, the tensile strength of peanut peg and stem-peg node ranged from 10N to15N, and the corresponding tensile strength of peanut-peg node ranged from 7N to 9N. The above study results could be used as important references to design a picker and thresher of peanuts and to determine the optimal picking time, as well as deeply research the mechanisms of picking up and threshing with less loss of dropping and damage.
    2008,24(3), DOI:
    Abstract:
    Owing to the fact that there were geometric nonlinearities, physical nonlinearities and contact nonlinearities during the working of vehicle air spring, it is difficult to estimate its mechanical property accurately using empirical formula. In recent years, with the development of nonlinear finite element theory and computer techniques, it is possible to estimate the mechanical property of air spring using nonlinear finite element method. Based on the study of an air spring used on a certain kind of vehicle suspension system, its three-dimensional finite element model was developed. In the model, the cord reinforced rubber bellow was simulated by both Mooney-Rivlin constitutive model and Rebar model, and the listrium and piston were simulated by rigid-body model. The nonlinear finite element analysis software ABAQUS was applied for computing the mechanical property of vehicle air spring. To further validate the reliability of the calculated results, the static characteristic test for measuring the mechanical property of air spring was carried out on electro-hydraulic servo experiment rig system of Instron 8800 air spring. The analysis indicates that these calculated results are in good agreement with the experimental results. Hence, nonlinear finite element method is an economical and practical approach to estimate mechanical property of vehicle air spring.
    2014,30(19):290-299, DOI: doi:10.3969/j.issn.1002-6819.2014.19.035
    [Abstract] (2702) [HTML] (0) [PDF 4.93 M] (9114)
    Abstract:
    Abstract: Studies of Erhai Basin indicate that Land use change by human activities in the watershed is the leading cause of regional climate, hydrology, water quality and ecological changes. Therefore, it is necessary to study the relationships between human activities and land use/cover change (LUCC), which is beneficial to offer the scientific decision support for reasonable land planning and land use. Combined with GIS technologies of spatial analysis and using the artificial intelligence algorithm Ant Colony Optimization(ACO) for optimizing, in this paper, we applied the method of Agent-based modeling to establish the spatiotemporal process model of LUCC in order to simulating the dynamic change of land use in whole watershed. Firstly, we made a choice and evaluation for impact factors of land use changes, as well as constructions of the cost of land use change equations in order to construct more reasonable decision rules of land use choice. Then, we have extracted three agents composed by microcosmic and macrocosmic systems which were farm agent, resident agent and government agent. Also, microcosmic rules of decision and behavior were created according to ACO. On the other hand, we have established macrocosmic decision rules according to a resistance coefficient system from the land use planning, as well as a comprehensive decision rule. And then, based on Java language and Repast platform of modeling, the program design, implementation and simulation of model were given in detail. Finally, the validation, calibration and verification of model and analysis of the simulated results were also conducted. Our conclusions from the experiment were three: 1) Ant colony algorithm was more effective in promoting the significant moving and decision of agents, and the simulated results gained better accuracies in both mathematics (up 5.6%) and geometry (up 3.4%) than using a random algorithm. However, the merit of ACO was not suitable for its use in all of land-use types. For an instance, there were no any improvements and sometimes even reduction in accuracy for those land-use types which were less affected by human activities, such as forest, grassland and wetland uses. Thereby, we suggested that ACO was more sensitive to interaction between human and land-use changes, and it was suitable for optimizing human behaviors and decisions of land-use transfer. 2) If the policy on land use was kept unchanged, the major contradiction between human and land in the future ten years should be the persistent reduction of agricultural land (127.64 hm2 cultivated lands and 11.20 hm2 garden lands) and the continuous increase of urbanized land (95.80 hm2). This indicated a big cost of urbanization in Erhai Lake Basin, which also gave a warning of increasing impervious surfaces (IS) produced in future rapid urbanization, and the IS may raise risks of urban non-point source pollution in the future. 3) The fast increasing of wetlands (growth rate of 50.07% was the fastest in the change of all land use types) indicated that the governmental land use policies to ecosystem protection have played a better role in macro control of land resources allocation. From this research, we suggested that the local government should maintain the existing strategies of ecological environment protection to reduce the risk of water pollution in Erhai Lake Basin. The competition in the market economy model of land-resources-commercial should be encouraged to balance the next major conflicts between human activities and land resources.
    2010,26(11):1-7, DOI:
    [Abstract] (32257) [HTML] (0) [PDF 0.00 Byte] (8862)
    Abstract:
    The problems and challenges for agricultural water management are markedly different from 50 years ago. To meet the increasing global demand for food, new challenges have been coming: increasing farmers’ income, boosting rural economy, reducing poverty, adapting climate change and protecting the ecological environment, under the conditions of the scare water resources. Therefore, the improvement of strategies and countermeasures relevant to the development of agricultural water management is nessary starting from the thinking of interdisciplinary and various sectors. The strategies include that developing water-saving agriculture, maintaining the service functions of the ecological system, increasing investment in irrigation, promoting rain-fed agriculture, improving and increasing water productivity, reducing poor population, preventing and alleviating the degradation of land and water environmental quality, reducing the risk in waste water irrigation, and strengthening policy and institution building. The efforts in improving agricultural water management and increasing agricultural productivity depend on the rational selection of the above strategies and the benefit tradeoffs.
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    1999,15(3):33-38, DOI:
    Abstract:
    Ninety eight observing points by a square of 10m×10m were made in a wheat field approximate 1 hm2. Soil samplers were obtained from each point under two layers of 0~20 cm and 80~100cm with different soil moisture and different time. Ammonia、NO3-N、Olsen-P in the soils of 0~20 cm and 80~100 cm, organic matter and total-N in surface soil (0~20 cm) were measured. The geostatistics theory was applied to analyze the data, the results indicated that both NH-N in bottom soil and organic matter in surface soil showed a normal distribution, others with a lognormal distribution. The rational sample number was determined within a given precision at a known confidence level. Semivariance analysis gave that those nutrients were correlated in a given spatial range. The Kriging method was applied to calculate the unobserved points and generate the contour map. Preliminary analysis was made for the spatial dynamic variability of those nutrients in different time. These results shows some merit in increasing nitrogen use efficient and precision agriculture.
    2003,19(2):210-213, DOI:
    Abstract:
    Analysis on land consolidation benefits is an important part of the study on the land consolidation theory and practice. It can improve land consolidation theory and guide land consolidation practice to an analysis on its on economic, environment and social development. Though the aims and content of land consolidation are different in different countries, the practice showed that it could increase production and income, protect and improve the environment and provide farmers with fine living conditions. So the comprehensive benefits of land consolidation are the aggregation of economic, environmental, social and landscape benefits. The economic benefits of land consolidation are the effect of the practice upon the national economy and the farmers of land consolidation areas. The environmental benefits of land consolidation are the effect of the practice upon the structure and function of natural ecosystem and the environment. The social benefits of land consolidation are the effect of the practice upon the rural environment, and social economy, as well as the reasonable use of natural resources. The landscape benefits of land consolidation is the effect of the practice upon the rural landscape.
    2009,25(12):211-217, DOI:
    Abstract:
    There are some problems such as statistics lacking, unsuitability of the ratio of main product output to that of by-product of the crops in the estimation of straw resources. The paper chooses the revised ratio of main product output to that of by-product of crops and estimates the quantity of straw resource comprehensively and systematically. The estimation results show that the total straw yield in China has a generally increasing trend with the improvement of agricultural comprehensive production capacity, and China is the biggest country in straw resources that its total output of straw resources in 2005 reached 841 831 200 t, which the straw of food crops was the main source. It has a great potential for rice husk, corncob, bagasse to develop new energy.
    2002,18(1):22-26, DOI:
    Abstract:
    Aquasorb is a kind of sodium polymer with characteristic of absorbing and storing water. There are many types and varieties in commercial market. The purpose of this study is to determine the chemical features of sodium polymer and its effect on soil improving, and to analyze the influence on crop yield and fertilizer use efficiency in farming field. The result showed that and electronic conductivity (EC) were increased but not so high when the concentration of sodium polymer was raised. pH value was almost not affected. Ions with two positive charges, such as [Ca2+] and [Mg2+] have a negative impact on drinking water characteristic of sodium polymer markedly, which is stronger than that of one positive or negative charge, such as Na+ and H2PO4-. It does not influence the drinking water of sodium polymer for different concentrations of urea. When soil is added with sodium polymer, the water holding capacity is raised, the aggregate of the soil is increased, this feature on sandy soil is more remarkable than that on clay soil, especially when there is 0.005% to 0.01% sodium polymer in soil. The test indicated that over 90% water holding by the sodium polymer can be used by plant. Based on the current results, it can be concluded that there are four aspects for action of sodium polymer, (1)conserving water by itself, (2)raising water holding by improving soil structure, (3)enhancing growth of plant and raising fertilizer use efficiency, (4)and reducing soil evaporation. The field test result showed that using sodium polymer by hole method at 15 kg/hm2, the yields of corn and potato were increased by 22% and 16%, and the ratios of investment to benefit were 1∶3.5 and 1∶4.2, respectively. When sodium polymer was mixed with urea or with urea and phosphorus fertilizer, the urea and phosphorus fertilizer use efficiencies were increased by 18.7% and 27.1%, respectively.
    2007,23(9):276-282, DOI:
    Abstract:
    Development trends of biomass energy in the future were analyzed on the basis of comprehensive evaluation of biomass energy resources, industry development and policy environment in China. Biomass resources are rich in China. Biomass energy industry begans to take shape: biogas industry was basically formed, fuel ethanol throughput reached 1.02 million tons per year, the technology that fuel ethanol was produced by use of non-food crops such as sweet sorghum stalks was developed and demonstration project of direct furl-fired generation with straw began to connect to power grid. Macro-policy environment to promote the development of biomass energy industry gradually formed. Therefore, the conclusions were concluded that development emphasis of biomass energy industry in the future in China would focus on biogas and biogas power generation, liquid fuels, biomass solid pellet fuel and biomass power generation; policies for the development of biomass energy industry would be further improved; the technology level would be further improved. There will be more large-scale enterprises to participate in this industry; it is sure that biomass energy industry will become a new growth point of Chinese national economy.
    2008,24(12):291-296, DOI:
    Abstract:
    According to document analysis and field survey, various evaluating indices of crop straw resource were used to finish the research and evaluation on main crop straw in China. The results showed that the theoretical resource amount of the 5 main crop straws was 433 million tons in China, including 176 million tons for the energy utilization. The resource could be distributed as ‘two-high and two-low’ that per capita amount of the resource was ‘high in north and low in south’ and per planting area of the resource was ‘high in east and low in west’. According to the resource distributing characteristics in each region. The whole country was divided into main developing area (Northeast, Meng-Xin and North region), proper developing area (Southwest, middle-lower Yangtze River and South region) and limited developing area (Loess Plateau and Qinghai-Tibet region). Different developing measures should be used in each region.
    2004,20(5):1-5, DOI:
    Abstract:
    Concepts and bounds of terms of biomass, biomass resources and biomass industry were defined in this paper. Developmental potential of biomass resources in China was analyzed. Aiming at the problems of agriculture, farmers and rural development at present and national requirement of energy and environment securities in the next 10 to 15 years, four developmental trends of biomass industry in China and the world, including biomass power, ethanol, biodiesel, biopolymers and dedicated energy crops and trees were discussed. A developmental pattern of bioenorgy of modern biomass industry with agriculture and forestry was briefly introduced. It is significant for development of biomass industry to settle the problem of farms and accelerate the agricultural industrilization and rural development.
    1999,15(2):74-78, DOI:
    Abstract:
    Water retaining properties of water retaining BP agent manufactured in USA and its effect on soil and crops were studied. The results obtained were as follows: There were strong absorbretaining properties with BP,absorbing capacity in distilled water is 38.7 mL/g, there was a large change of imbibition in the range of 0~0.1 % solution concentration, the imbibition of 0.1 % solution concentration is 63 % in distilled water, the amount of available water absorbed is over 2/3; soil water physical characterictics were improved and water retention power increases as BP is added to soil; in the range of 0.01~1.5 MPa soil water potential, there were obvious increases in sand soil and heavy loam soil compared with that of light loam and middle loam soil; when BP is added to soil saturated hydraulic conductivity will decrease, soil evaporation properties have no obvious change, especially in sand soil; sand soil wheat pot experiment with BP added to soil showed that there were obvious increases in the weight of wheat root, root length and ratio of root and shoot, the nutrition condition of root system was better, and the wheat growth was improved.
    2005,21(8):169-173, DOI:
    Abstract:
    The status quo of agricultural residues was analyzed. As pollutants have four characteristics of huge quantities, bad qualities, low price and excessive danger. As resources have four application practices, namely, biomass energy, fertilizer, feed and biomaterial. The analysis shows that the potential as fertilizer and energy is huge. However, there are some limited factors and technical bottleneck in the future. In combination with socioeconomic developmental objectives, the developing strategy and strategical emphases for the resources of agricultural residues were presented. The direction is to develop Eco-Agriculture and Cyc-Economy, which depend on the policy guidance, technical support and investment to promote agricultural residues used as resource in the future.
    2006,22(11):269-272, DOI:
    Abstract:
    Increasing temperature and keeping soil moisture effect of mulching plastic film have brought a positive and important progress in agricultural productivity, and also the residue of mulching plastic film in the field has already become a negative factor that affected agricultural environment, which destroyed soil structure and harmed growth of crop. Based on results of domestic study on this issue, the authors comprehensively analyzed the application situation of mulching plastic film in agriculture, and the distribution characteristics as well as the influencing factors, the harm ways of the residue of mulching plastic film. According to the actual situation, the techniques of preventing and controlling measures for residue pollution of mulching plastic film were put forward.
    2007,23(5):81-87, DOI:
    Abstract:
    The study on the driving forces of rural residential land can instruct the consolidation of rural residential area, which is an important part of the study of inner law of rural residential area evolvement. Taking the Beijing mountainous area as study area, the driving forces of rural residential area change was analyzed based on GIS and SPSS using the logistic regression model by view of spatial coherence. The result indicate that the change of rural residential area is controlled by its former distribution and droved by the exterior driving forces under the interior driving forces context such as natural factors and location comprehensively. The change of rural residential area is a process that selecting the preferable location integrating the influence of the nature, local accessiblity and social-economy. The developing orientation of its driving forces is made to probe into the suitable consolidation modes in different localities, which will help to strengthen the management of rural residential area during the construction of new socialist countryside.
    2002,18(4):155-158, DOI:
    Abstract:
    A novel method for measuring individual leaf area of vegetables was developed using digital image processing techniques and scanner. Meanwhile, the measured data from digital image analysis was compared with the values from grid-counting method, leaf-copy and weighing method, instrumental scanning method, etc. The results show that there are close relationships between digital image processing method and the other traditional methods. Relative low variation in measured data was the dominant advantage of image processing method. It can be concluded that digital image analysis technique is suitable to measure leaf area of vegetable in combination with “Maximum length×width”ruler method through correlation and the calibration coefficients for rape (Brassica napus L) and water spinach (Ipomoea aquatica Forsk) were 0.792 and 0.818, respectively.
    2003,19(2):39-44, DOI:
    Abstract:
    With the help of GPS and GIS, spatial variability of soil property was measured and analyzed by using statistics and geo-statistics, which was tested in a 13.3 hm2 field of winter wheat. Sixty three sampling points were collected on a 50 m grid in soil surface (0~20 cm) of the field, and the points were oriented by GPS receipt machine. The soil property included total N, available N, organic matter, available P, available K, bulk density, the moisture content and electrical conductivity, which were studied using spatial distribution maps and semi-variograms that can explicitly express the random and structural of soil property. The research result showed that all soil spatial characters are normal distribution; bulk density exhibited weak spatial variability, and others exhibited moderate spatial variability; the soil organic matter, total-N, available N, available K and electricity conductivity have exhibited strong spatial correlation, and soil bulk density, available P and the moisture content have exhibited moderate spatial variability, and the range of soil properties correlation distance was 246.8~426.8 m. All these results can serve as a basis for precision fertilization, precision irrigation and precision management in farm.
    2002,18(1):165-168, DOI:
    Abstract:
    The research development of recent agricultural land evaluation in China was reviewed. The two method systems, ideological bases and practical significance raised respectively in newly formulated National Rules of Classification and Gradation of Agricultural Land and Rules of Soil Fertility Gradation of Cultivated Land were analyzed and compared. The classification and gradation evaluation of agricultural land developed from such low level researches on natural soil condition investigation for estimating yield, soil nature and basic soil fertility, etc. to management and evaluation of resource value integrated with land and human being. The existing two evaluation methods of agricultural land in China are the gradation system of soil fertility of cultivated land formulated by Minstry of Agriculture and the classification and gradation evaluation system of agriculturall and drafted by Ministry of Land and Resources. There exist differences between the two systems in analyses of evaluation indexes, objective levels of achievement application and links of front and back operation. Currently, the classification and gradation evaluation of agricultural land have been implemented across China, whose method system perfection is of great practical significance.
    2006,22(2):27-32, DOI:
    Abstract:
    Field experiments were conducted at Luancheng Station, Chinese Academy of Sciences in different precipitation years. The impacts of water supplied conditions on root distribution, yield and water utilization efficiency(WUE) of winter wheat under different irrigation treatments were analyzed in order to supply a basis for optimum irrigation mode which could increase the yield and improve water utilization efficiency. The results indicated that most roots were concentrated in the upper 80 cm soil layer, and the density of roots declined exponentially downward with the increase of the soil layer depth. Considering water consumption in different soil layers, and the relationships among yield, water utilization efficiency and total water consumption, the optimal irrigation mode in North China plain was put forward, i.e., no irrigation in rain-full years, one time irrigation at jointing stage in normal years and two times at jointing stage and booting stage in dry years with the suitable water quota of 60 to 75 mm each time, which not only increased the winter wheat yield, but also benefited to using the deep soil water and improving the water utilization efficiency.
    2000,16(3):24-27, DOI:
    Abstract:
    Crop Regulated Deficit Irrigation (RDI),based on the crop-water relations,is an irrigation technique with high yield and water use efficiency. The beneficial effect of moderate water deficit was analyzed using the data of field experiments in Shaanxi,Gansu and Xinjiang. It showed that RDI should be applied at the early growth stage. The degree of water deficit can reach 45%~50% of field capacity,which has no bad effect on crop yield and can increase crop water use efficiency obviously. And some problems of RDI were also disscussed.
    2005,21(7):168-174, DOI:
    Abstract:
    The importance of and the need to secure food safety and facilitate international trade through establishing a traceability system for domestic animals and livestock products were discussed, and the essential components and characteristics of domestic animal traceability system were also introduced in this paper. Several animal identification technologies including information and network technology were compared and summarized. The history of implementation and evolution of legislative regulation of traceability systems in developed countries were reviewed; the main issues which hamper the implementation of traceability system were discussed. A pilot project of a Chinese traceability system, in which new technologies were developed, was also proposed. The trends and direction for the development of traceability system was highlighted, and findings of this paper could provide a basis for establishing a national traceability system for domestic animals and livestock products which is feasible to the situation of China.
    2002,18(2):49-52, DOI:
    Abstract:
    Study was carried out on Fluvo aquic soil of low fertility coming from Huanghe River plain for 14 years. The results show that the long term returning straw to soil changes soil properties. Soil organic matter, soil porosity, availible N,Zn,Fe,Mn and enzyme are all positively related to the amount of straw applied remarkably, while soil specific weight is negatively correlative. These indexes are affected by climate, plant growth seasons and soil texture, etc. The result of combination use of straw and fertilizer is better.
    2000,16(5):26-30, DOI:
    Abstract:
    Crop coefficient is the basic parameter for determining crop water requirement. In this paper, two methods proposed by FAO are described. One is time averaged crop coefficient(Kc) approach, which is a simple and useful method. The other is dual crop coefficient approach with more complicated computations but more accurate results. Both approaches were validated with experimental results at Xiongxian Experimental Station, Hebei Province. The results showed that the Kc values calculated by FAO methods are close to that as estimated from experiment data. Both methods are valid to use for determination of crop coefficients on the North China Plain if there are no on site experiment data available.
    2004,20(1):7-12, DOI:
    Abstract:
    The advances of the greenhouse control system modes were discussed, and several typical greenhouse control system modes were introduced in this paper. The main problems restricting the application of the greenhouse control systems are their high cost and low intelligence due to the hardware topology frameworks of greenhouse control systems. The idea of distributed structure of greenhouse control mode based on CAN bus could decrease cost and also provide a valid way to solve its intelligent problem. At the same time, the development status in the future was given including internet-based control and management, fieldbus-based monitoring sensors and control actuators, and the standardization of control systems in greenhouse production.
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