2013年8月第29卷第16期

2013年8月第29卷第16期

Accession number:20133516679279
Title:Vacuum cooling retards degradation of cell wall matter in Agaricus bisporus
Authors:Tao, Fei (1); Gao, Haiyan (1); Ge, Linmei (1); Mu, Honglei (1); Chen, Hangjun (1)
Author affiliation:(1) Food Science Institute of Zhejiang Academic of Agricultural Science, Hangzhou, 310021, China
Corresponding author:Gao, H.(spsghy@163.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:264-268
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Vacuum cooling is a rapid cooling technique extensively used for cooling some agricultural and food products. The vacuum cooling technology is now gradually applied to the precooling treatment of agricultural products due to the advantages of quick cooling, easy operation, no constraint of packing containers, and energy savings. Consumption of Agaricus bisporus has increased substantially because of its delicacy, flavor and nutritional value. Agaricus bisporus is an excellent source of several essential amino acids, vitamins (B2, niacin, and folates), and minerals (potassium, phosphorus, zinc, and copper). Agaricus bisporus has a short shelf life of 3-4 days compared to most vegetables at ambient temperatures because it has no cuticle to protect it from physical or microbial attack or water loss. Loss of quality is caused by morphological changes due to maturation, discoloration, changes in texture and flavor, and losses of nutrients. Textural changes of fruits are accompanied by loss of neutral sugars, solubilization and depolymerization of the polysaccharides of the cell wall, and rearrangements of their associations, as the result of the combined action of several cell wall-modifying enzymes, acting in both pectic and hemicellulosic fractions. Recent studies on the structure of the plant cell wall have disclosed a large number and type of biochemical linkages between the components. Such linkages are potential targets for enzymatic action and draw attention to the putative involvement of several members of enzymes able to act and modify its structure in a developmental and coordinated way. The objective of this study was to determine the effect of vacuum cooling treatment on cell wall compositional changes and ultrastructure in fresh mushrooms during 15 d of post-harvest storage at 4°C. In this study, we investigated the change of cellulose content, cellulose activity, propectin content, WSP content, and the PG activity of Agaricus bisporus before and after vacuum cooling. We also studied changes in those properties during storage. The results showed that vacuum cooling treatment could retard the increase of cellulose activity and PG activity and slow down the reduction of cellulose content and propectin content. At the end of storage, the contents of cellulose and propectin of Agaricus bisporus without vacuum cooling treatment were decreased by an average of 58.0% and 62.07%, respectively. The significant difference was found between the Agaricus bisporus without and with vacuum cooling treatment (P<0.05). No sign of damage could be observed as a result of vacuum cooling the Agaricus bisporus. During the storage, the Agaricus bisporus with vacuum cooling treatment retained its structure better than without vacuum cooling.
Number of references:26
Main heading:Vacuum applications
Controlled terms:Agricultural products - Amino acids - Cells - Cellulose - Cooling - Cytology - Energy storage - Enzymes - Food products - Fungi - Storage (materials)
Uncontrolled terms:Agaricus bisporus - Cell walls - Compositional changes - Essential amino acids - Hemicellulosic fractions - Morphological changes - Post-harvest storage - Ultrastructure
Classification code:821.4 Agricultural Products - 815.1.1 Organic Polymers - 702 Electric Batteries and Fuel Cells - 822.3 Food Products - 694.4 Storage - 633.1 Vacuum Applications - 461 Bioengineering and Biology - 641.2 Heat Transfer
DOI:10.3969/j.issn.1002-6819.2013.16.033
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679265
Title:Design and test of multi-point soil resistivity measurement system based on wireless
Authors:Lu, Chao (1)
Author affiliation:(1) College of Physics and Electrical Engineering, Shaanxi University of Technology, Hanzhong 723000, China
Corresponding author:Lu, C.(27304487@qq.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:142-150
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:This paper describes the design of a wireless multi-point soil resistivity measurement system. The system is composed of many slaves and a host. According to "the principle of current-voltage four terminal methods," this paper presents a sensor made in our laborator. It included an A/D conversion chip MCU, wireless communication circuit, the sine wave generating circuit, AC constant current source circuit, sensor electrode, differential circuit, conversion circuit, amplifier circuit, and digital potentiometer effective value. It can reduce the interference of soil solute movement. The system was established by measuring a platform of master-slave communication. The slave completes the soil resistivity data acquisition and transmission. A number of slaves can be extended according to the requirements of the measuring point. The host comprised a single chip computer, a liquid crystal display circuit, external data storage circuit, wireless communication circuit. And the key circuit completes the soil resistivity data receiving, processing, display, and storage function. Wireless communication circuit adopts nRF24L01 wireless module, and can constitute a "one-to-many" communication network. In order to stabilize amplitude alternating test design of the constant current source, the simulation test of soil impedance changes using a variable resistance, used for the test of stability constant current source, the relative error of the elongation is 2.63%, and it has good stability. Outdoor wireless transmission distance can reach 95m, indoor reached 75m. The system effectively solves the multi-point soil resistivity measurement consistency problem. There was a good linear relationship between salt content of soil and soil resistivity measured systematically, the higher is the salinity, the smaller is the soil resistivity measured. There was a good linear relationship between the soil resistivity measured systematically and the amount of water, the larger is the add water amount, the smaller is soil resistivity measured. The design of the system is novel, is simple to operate, with good portability, and soil resistivity data to detect intelligent automated multiple locations can be moved at any time. At the same time, the construction is convenient, has a broad application.prospect in production, and can be widely popularized.
Number of references:29
Main heading:Soils
Controlled terms:Analog to digital conversion - Data handling - Design - Digital storage - Electric conductivity - Interference suppression - Liquid crystal displays - Measurements - Potentiometers (electric measuring instruments) - Potentiometers (resistors) - Sensors - Soil testing - Testing - Wireless telecommunication systems
Uncontrolled terms:Constant current source - Differential circuits - Digital potentiometer - Micro control unit - Single chip computers - Soil resistivity measurements - Wireless communication circuits - Wireless transmissions
Classification code:722 Computer Systems and Equipment - 723.2 Data Processing and Image Processing - 801 Chemistry - 944 Moisture, Pressure and Temperature, and Radiation Measuring Instruments - 941 Acoustical and Optical Measuring Instruments - 942.1 Electric and Electronic Instruments - 943 Mechanical and Miscellaneous Measuring Instruments - 942 Electric and Electronic Measuring Instruments - 717 Optical Communication - 716 Telecommunication; Radar, Radio and Television - 408 Structural Design - 423.2 Non Mechanical Properties of Building Materials: Test Methods - 483.1 Soils and Soil Mechanics - 701.1 Electricity: Basic Concepts and Phenomena - 704.1 Electric Components - 711 Electromagnetic Waves
DOI:10.3969/j.issn.1002-6819.2013.16.018
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679271
Title:Impact of climate change on heat and cold stress of cow breeding in Beijing
Authors:Dong, Xiaoxia (1); Liu, Haomiao (4); Zhang, Chao (1); Yu, Haipeng (1); Ma, Chong (5); Yi, Xiaoyan (6); Li, Zhemin (1)
Author affiliation:(1) Agricultural Information Institute of Chinese Academy of Agricultural Sciences, Beijing 100081, China; (2) Key Laboratory of Agri-information Services Technology, Ministry of Agriculture, Beijing 100081, China; (3) Key Lab of Intelligent Agric Early Warning Tech and System of Chinese Academy of Agric Sciences, Beijing 100081, China; (4) Beijing Innovation Team of Modern Agricultural Industry Technology System, Beijing 100081, China; (5) Beijing Lvhe Cattle Farms Co. Ltd., Beijing 100025, China; (6) Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China
Corresponding author:Li, Z.(lizhemin@caas.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:198-205
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:The impact of climate change on cow breeding has become increasingly prominent, and in some areas the external environment of heat stress or cold stress increased. This research adopts two indicators-the temperature and humidity index (THI) and wind chill temperature (WCT), analyses the daily change characteristics of THI and WCT in Beijing from 1951 to 2012, focusing on the analysis of the influence of variation of stress environment of cow breeding to climate change. The study showed that: 1) Over the past 60 years, the temperature of Beijing increased 1.93°C. Not only the annual rainfall, but also the relative humidity decreased significantly in Beijing from the new century. The average annual relative humidity was only 50% from 2010 to 2011, which declined 10 percent compared with 1951-1959. According with the national climate change trend, the climate change of Beijing showed the typical characteristics of warm and dry. 2)Just from the temperature environment, climate change of Beijing resulted in the number of days markedly increasing that maximum temperature more than 32°C, and the number of days obviously decreasing that minimum temperature less than -5°C. The number of days that the maximum temperature was more than 32°C added 11 days from 2000 to 2012 compared to 1950-1959, while the number of days that the minimum temperature was less than -5°C was reduced by 28 days. In other words, climate change has exacerbated the heat stress temperature environment of cow breeding in Beijing and improved cold stress temperature environment from the view of the absolute temperature. 3) From the THI, although the number of days that the maximum temperature was more than 32°C obviously raised from the new century, the climate change of warm and dry did not significantly increase the degree of heat stress in cow breeding, which was due to the observably decreased relative humidity. From the WCI, the number of days were reduced in which the wind-chill index was less than or equal to -10, along with the significantly reduced number of days that the minimum temperature was less than -5°C. The degree of cold stress evidently lightened in Beijing, but it was still mild cold stress mainly in cow breeding. This research still reminds us that the cold and heat stress environment presented the situation of "Double Ascending" in Beijing since 2008, especially the cold stress environment significantly increased.
Number of references:36
Main heading:Climate change
Controlled terms:Stresses - Temperature - Thermal stress
Uncontrolled terms:Annual rainfall - Annual relative humidity - Cow - External environments - Maximum temperature - Minimum temperatures - Temperature and humidities - Temperature environments
Classification code:421 Strength of Building Materials; Mechanical Properties - 451 Air Pollution - 641.1 Thermodynamics
DOI:10.3969/j.issn.1002-6819.2013.16.025
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679277
Title:Multi-objective optimization of land use structure in western Jilin province based on system dynamics
Authors:Li, Xiuxia (1); Xu, Long (1); Jiang, Enci (1)
Author affiliation:(1) College of Tourist and Geoscience, Jilin Normal University, Siping 136000, China
Corresponding author:Li, X.(jykx@263.net)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:247-254
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Optimizing land use structure is the foundation and core of the overall plan for land use. At present, domestic scholars have mostly used system dynamics (SD) model, multiobjective programming (MOP) model to optimize land use structure, In order to overcome the limitations of single model, achieve the compensation of mutual advantages, and to raise the accuracy, reliability, feasibility and operability of date of prediction scheme, this article combines the SD model with the MOP model and constructs SD-MOP integrated model. First, combining the research purpose, it defines the system boundary and establishes the level and rate variable system, divides the system into 3 subsystems: population system, economic system and land use structure system, and utilizes Vensim software platform to establish the causality graph of land use structure system and constructs the SD model of land use structure system, then makes initial simulation of land use structure according to historical data. Second, it utilizes sensitivity model to identify the sensitive factors of land use structure. And takes the sensitive factors as the decision variables, while relying on the SD model to establish objective functions of economic benefit and ecological benefit, forming constraint conditions of objective functions to construct MOP model, and solves it. Finally, puts the solution into SD model to optimize land use structure. In the case of western Jilin in this article, we utilized 2 periods TM remote sensing images of the year 2000 and 2010 and combined with the field investigation, we interpreted the remote sensing images accurately, the accuracy of interpretation was approximately 90%-95%. Take the interpretation as the source of land use structure data and the Statistical Yearbook of the Socio-economic as the source of economic data, we then simulated and optimized the land use structure of western Jilin using the model of SD-MOP based on the objectives of economy and ecology. The result shows that: if we utilize the SD model, by 2020 the growth rate of economic benefits will reach 12.35% compare to the 10.33% of 2015, the economic benefits will increase remarkably, but the growth rate of ecological benefits will go down to 0.61% compare to the 3.43% of 2015, yet the eco-efficiency will not improve. Although it would promote the economic development of western Jilin, it would also lead to the deterioration of the ecological environment and influence land ecological balance, it would make the utilization of land resources unsustainable and finally influence the development of regional economy. So the SD scheme is unfeasible. If we utilize SD-MOP model to optimize the land use structure of western Jilin province, with an increase of 7.43% in economic benefit and 3.09% in ecological benefit, cultivated land and construction land will be increased by 2705.74 km2 and 349.89 km2 respectively, but woodland, grassland, water area, unutilized land will be decreased by 12.75 km2, 11.51 km2, 270.43 km2 and 2772.56 km2 respectively. Compared with Single objective model of SD, the increase amplitude of the cultivated land will be decreased by 31.55% and 14.97% respectively, and the woodland, grassland, waters and unutilized land will be decreased by 42.70%, 20.99%, 42.68%, 29.34% respectively. It will not only develop the economy and protect the ecological environment, but also will improve the land use efficiency and realize the sustainable utilization of land resources. The conclusions are: SD-MOP scheme is better than SD scheme of a single objective. The SD-MOP integrated model is worth popularizing since it would optimize land use structure scientifically and systematically and the optimized results is objective and reasonable.
Number of references:31
Main heading:Economics
Controlled terms:Computer programming - Computer simulation - Ecology - Image reconstruction - Land use - Multiobjective optimization - Natural resources - Optimization - Regional planning - System theory
Uncontrolled terms:Constraint conditions - Ecological environments - Jilin Province - Multiobjective programming - Remote sensing images - SD-MOP model(system dynamics-multi-objective programming) - Single objective models - Sustainable utilization
Classification code:961 Systems Science - 921.5 Optimization Techniques - 741 Light, Optics and Optical Devices - 723.5 Computer Applications - 723.1 Computer Programming - 971 Social Sciences - 512 Petroleum and Related Deposits - 454.3 Ecology and Ecosystems - 444 Water Resources - 403.2 Regional Planning and Development - 403 Urban and Regional Planning and Development - 501 Exploration and Prospecting
DOI:10.3969/j.issn.1002-6819.2013.16.031
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679272
Title:Back wall stereo-cultivation of strawberry improves temperature in Chinese solar greenhouse in winter
Authors:Song, Weitang (1); Li, Yafei (1); Qu, Mingshan (3); He, Huaming (1); Zheng, Liang (1); Xing, Wenxin (1)
Author affiliation:(1) College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, China; (2) Key Laboratory of Agricultural Engineering in Structure and Environment, Ministry of Agriculture, Beijing 100083, China; (3) Beijing Soil and Fertilizer Working Station, Beijing 100029, China
Corresponding author:Song, W.(songchali@cau.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:206-212
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:In Chinese solar greenhouse production, pipe stereo-cultivation of vegetables or strawberry on the greenhouse back wall could improve the space utilization and increase the cultivation area and yield. However, it is possible that shading of pipes and plantings may reduce the back wall heat storage and result in the decreasing of internal temperature of the greenhouse in winter. The objective of this study is to find out whether the back wall pipe cultivation affects the temperature variations of solar greenhouse in winter. In this article, the experiment was conducted in two solar greenhouses of a strawberry park in suburb Beijing. The structure type, growing conditions and management methods of the two experimental greenhouses are exactly the same. Pipe strawberry cultivation facility was installed on the back wall (2.3m high) in one solar greenhouse. The pipe cultivation facility is composed of 4 rows of horizontal PVC pipe, center distance of each row is 40 cm, diameter of the pipe is 160 mm with 9cm width's notch on the upper side. Cultivation substrate (peat: perlite: vermiculite = 1:1:1 (v/v), depth is 10 cm) and drip irrigation to fertilizer nutrient solution were used. Five measurement points were arranged in both greenhouses, to measure the temperature of strawberry growth canopy and 1.5 m above the ground. Temperature condition of the two greenhouses for 31 days (from Jan. 20th, 2013 to Feb. 20th, 2013) was continuously monitored, and the temperature variations of solar greenhouse with equipment (ESG) and solar greenhouse with no equipment (NSG) of three typical climatic conditions (sunny, cloudy and snowy) were analyzed.The results showed that the monthly mean temperature in ESG was 0.84°C higher than that in NSG, and the maximum and minimum of daily temperature difference was 2.22°C and 0.14°C, respectively. In sunny days, daily mean canopy temperature and daily mean air temperature at 1.5m height in ESG were 10.68°C and 11.04°C, but they were 10.68°C and 11.04°C in NSG, respectively. The highest and lowest canopy temperatures in ESG were 24.70°C and 4.68°C, compared to they were 20.70°C and 4.10°C in NSG. The highest and lowest air temperatures at 1.5m height were 26.95°C and 4.65°C in ESG, while they were 22.73°C and 4.13°C in NSG. It could be inferred that the sunny day temperature condition in ESG was better than in NSG. In the cloudy and snowy days, there was no significant difference in temperature condition in ESG and NSG. Therefore, it can be concluded that back wall stereo-cultivation of strawberry in solar greenhouse increased the internal temperature in winter. There is a promising prospect of back wall stereo-cultivation and it is an efficient cultivation technology worthy of popularization and application in Chinese solar greenhouse.
Number of references:26
Main heading:Greenhouses
Controlled terms:Atmospheric temperature - Cultivation - Fruits - Heat storage - Irrigation - Polyvinyl chlorides - Solar heating - Temperature - Temperature distribution
Uncontrolled terms:Back wall - Chinese solar greenhouse - Cultivation substrates - Mean air temperatures - Strawberry - Temperature conditions - Temperature variation - Typical climatic conditions
Classification code:443.1 Atmospheric Properties - 641.1 Thermodynamics - 641.2 Heat Transfer - 643.1 Space Heating - 815.1.1 Organic Polymers - 821 Agricultural Equipment and Methods; Vegetation and Pest Control
DOI:10.3969/j.issn.1002-6819.2013.16.026
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679266
Title:Monitoring drought dynamics of China using passive microwave remote sensing technology
Authors:Chen, Xiuzhi (1); Su, Yongxian (3); Li, Yong (3); Chen, Shuisen (3); Han, Liusheng (3)
Author affiliation:(1) South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; (2) Henan Key Laboratory of Agrometeorological Support and Applied Technique, China Meteorological Administration, Zhengzhou 450003, China; (3) Guangzhou Institute of Geography, Guangzhou 510070, China; (4) Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; (5) University of Chinese Academy of Sciences, Beijing 100049, China
Corresponding author:Li, Y.(gz_liyong@21cn.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:151-158
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Drought is a recurrent complex phenomenon that affects nearly all climatic zones in the world. It is one of the major natural hazards in China, resulting in considerable economic, social, and environmental costs. Preparation for drought should be an important part of policies. Therefore, it is necessary to develop a dynamic and real-time drought monitoring approach in China. Remote sensing technology is one feasible way. However, the main drought indices of remote sensing for monitoring drought dynamics at present are based on visible and near infrared bands. They are always seriously impacted by rainfalls, clouds, vegetation, and terrain conditions. Hence, current drought monitoring technologies cannot meet the needs in south China, where the weather is always cloudy. Passive microwave emissions can penetrate non-precipitating clouds, thereby providing a better representation of land surface parameters under nearly all sky conditions. What is more, daily passive microwave data are available from microwave radiometers as compared to optical sensors like Landsat TM, ASTER, or MODIS, of which only weekly series products are available. So passive microwave remote sensing has unique advantages in long-time drought monitoring over those based on visible and near infrared bands. In this study, we first developed a semi-empirical model for retrieving land surface temperature using the AMSR-E C-band (6.9GHz) and X-band (10.7GHz) passive microwave remote sensing data. The approach provided a good retrieval accuracy of land surface temperature (error=2.54°C, R2=0.79). Next, this paper built an empirical relation between the AMSR-E 6.9GHz Microwave Polarization Difference Index (MPDI) and the NOAA-AVHRR Normalized Differential Vegetation Index (NDVI). Further, we improved the Vegetation Supply Water Index (VSWI) on the basis of the relation between NDVI and MPDI. Then, we used the new-developed drought index to monitor the drought dynamics of China in 2009. Results showed that many regions and cities of China (with red and yellow color) were attacked by the drought disaster in different degrees at the national level. The drought conditions were mainly distributed in Southwest (Yunnan, Guizhou and Guangxi Province, etc.), the Inner Mongolia Autonomous Region, northeast of Heilongjiang Province, Bohai region ( Liaoning, and Hebei Province), Jianghuai and Huanghuai region (Henan, Anhui, Shanxi and Shaanxi Province), and the Western region (Xinjiang Autonomous Region, Tibet Autonomous Region and Qinghai Province). The remote-sensed droughts were on the whole consistent with the actual situation of China in 2009 (http:www.gov.cn/jrzgv/). The field statistical data of the Meteorological Bureau showed that the average rainfall of China in 2009 was 565.8 mm, about 10 percent less than the same periods of past years (606 mm). What is more, the average temperature of China was 10.7°C in 2009, about one degree higher than the same periods of past years (9.7°C). Analysis results indicated that sustained high temperatures and fewer rainfalls were direct factors that induced the serious drought disaster of China in 2009. The new drought index had a significant negative correlation with the corresponding AMSR-EL3 soil moisture data (R2=0.75; RMSE=0.02 g/cm3). In all, the drought monitoring method proved to be effective in describing the land surface drought conditions of China.
Number of references:28
Main heading:Drought
Controlled terms:Atmospheric temperature - Disasters - Dynamics - Microwave devices - Monitoring - Rain - Remote sensing - Soil moisture - Vegetation
Uncontrolled terms:Inner Mongolia autonomous regions - Land surface temperature - Normalized differential vegetation indices - Passive microwave remote sensing - Passive microwave remote sensing technology - Remote sensing technology - Supply waters - Visible and near infrared
Classification code:944 Moisture, Pressure and Temperature, and Radiation Measuring Instruments - 943 Mechanical and Miscellaneous Measuring Instruments - 942 Electric and Electronic Measuring Instruments - 941 Acoustical and Optical Measuring Instruments - 931.1 Mechanics - 821 Agricultural Equipment and Methods; Vegetation and Pest Control - 731.1 Control Systems - 715 Electronic Equipment, General Purpose and Industrial - 714 Electronic Components and Tubes - 484 Seismology - 483.1 Soils and Soil Mechanics - 443.3 Precipitation - 443.1 Atmospheric Properties
DOI:10.3969/j.issn.1002-6819.2013.16.019
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679269
Title:Test and preparation of microelectrode in applications of self-referencing ion electrode technique
Authors:Xue, Lin (1); Zhao, Dongjie (1); Hou, Peichen (2); Wang, Xiaodong (2); Wang, Yuan (1); Wang, Cheng (2); Wang, Zhongyi (1); Huang, Lan (1)
Author affiliation:(1) College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China; (2) National Engineering Research Center for Information Technology in Agriculture, Beijing 100097, China; (3) College of Information Technology, Beijing Union University, Beijing 100101, China
Corresponding author:Huang, L.(hlan@cau.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:182-189
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:An self-referencing ion electrode technique provides a novel electrophysiological tool which can non-invasively measure the dynamic influxes and effluxes of ions from cells and organs in vivo. In fact, the foundation of this technique is the fabrication and performance test of an ion selective microelectrode (ISME). In this paper, the K ISMEs with good performances were obtained. We elaborated the procedure to prepare the glass micropipettes and to fill the pipettes with internal filling solution and liquid ion exchangers (LIX) of potassium, and then estimated the performance of these ion selective microelectrodes. Measurement of tip size, measuring method of resistance, testing of detection range, Nernstian slope, and response time, were described in detail. Ion selective microelectrodes were calibrated before and after experiments using two or more different kinds of concentrations of K within its operating range based directly on the potentiometric analysis. The procedure for ion selective microelectrodes fabrication is strict. The electrodes (the diameter of the apex of the tip was 1~9 μm) were pulled from non-filamented borosilicate glass capillaries (TW150-3, World Precision Instruments, USA) on a vertical micropipette puller (WD-2, Chengdu Instrument Factory, Chengdu), oven dried, and then silanized by injecting 2 mL of 5% dimethyldichlorosilane (Sinopharm Chemcial Reagent Co. Ltd, Beijing) with n-hexane as the solvent in a glass preparation chamber at 150°C. Afterwards, dried and cooled electrode blanks were back-filled with a 100 mmol/L KCl solution. Immediately after back-filling, the microelectrode tips were front-filled with liquid ion exchangers of potassium (60031, Sigma, USA). Furthermore, some of the factors that affect the performance of the microelectrode in the preparation were discussed in detail. The ISME's resistance reaches to 108~109 Ω filling with LIX (length is 150~210 μm), much higher than that which occurs without LIX. The detection range obtained by the K ISME is linear within a wide range of 0.01~500 mM KCl solutions with the slope of 53.095 mV per decade, and R2 of 0.9998, which means the K ISME response is in accordance with the Nernst equation. Besides the attainable Nernstian response range, the response time t<inf>95%</inf>, from the beginning of that ISE immersed into the K ion standard solutions with two concentrations, 1 and 100 mmol/L KCl, with 8 assays each concentration, to the 95% of stable potentials, is less than 1s. These measurements were made at room temperature (20~25°C). The results show that the fabrication of the ion selective glass microelectrodes is the key to obtaining the high performance of the microelectrode. The parameters of microelectrodes, i.e. tip size, resistance and response time, etc. are very important in practical application. This work can provide a reference basis for the fabrication and application in SIET of ion selective microelectrodes. Moreover, the standardized fabrication is the precondition to measure the dynamic influxes and effluxes of ions from cells and organs in vivo using the SIET.
Number of references:22
Main heading:Microelectrodes
Controlled terms:Borosilicate glass - Electrophysiology - Fabrication - Ion exchangers - Ions - Liquids - Organic solvents - Testing
Uncontrolled terms:Borosilicate glass capillary - Dimethyldichlorosilane - Glass microelectrode - Ion selective microelectrodes - Nernstian slope - Non-distructive examination - Potentiometric analysis - Silanizations
Classification code:931.2 Physical Properties of Gases, Liquids and Solids - 913.4 Manufacturing - 812.3 Glass - 803 Chemical Agents and Basic Industrial Chemicals - 802.1 Chemical Plants and Equipment - 801.2 Biochemistry - 801 Chemistry - 701.1 Electricity: Basic Concepts and Phenomena - 423.2 Non Mechanical Properties of Building Materials: Test Methods
DOI:10.3969/j.issn.1002-6819.2013.16.023
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679263
Title:Constant characteristic and model verification of saline soil dielectric in arid area
Authors:Lei, Lei (1); Tiyip, Tashpolat (1); Ding, Jianli (1); Jiang, Hongnan (1); Yao, Yuan (1); Sun, Yongmeng (1); Xia, Jun (1); Kelimu, Ardak (1)
Author affiliation:(1) College of Resource and Environment Sciences, Xinjiang University, Urumqi 830046, China; (2) Key Laboratory of Oasis Ecology (Xinjiang University) Ministry of Education, Urumqi 830046, China
Corresponding author:Ding, J.(Ding_jl@163.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:125-133
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Due to its unique superiority on soil property monitoring, microwave remote sensing is considered to be one of the most valuable means of soil property detection. Being a property of soil related to moisture in arid and semiarid regions, the salinity of soil has negative impact on crop yield. But there is little formal study corresponded to the application of microwave remote sensing on monitoring of soil salinity. Additionally, the dielectric properties are the basis of microwave remote sensing for earth observation, and also the key parameters of relationship establishment between the backscattering coefficient and soil parameters (moisture, salt content). In the present study, the corrective moist salt soil Dobson dielectric model was adopted as a fundamental model to simulate the soil dielectric constant. We also analyzed the response of soil dielectric constants to model parameters and verified the applicability of the corrective moist salt soil Dobson dielectric model by using field collected data at Wei-kuqa river oasis. We found that: 1) In low frequency regions (i.e., 0.5 < f < 5 GHz), soil dielectric constant has an obvious response to soil volumetric water content and soil salt content; 2) With a relatively high correlation coefficient (R > 0.95) of the corresponding linear regression model, the soil moisture content significantly correlated to the real part of soil dielectric constant; 3) Based on obvious response of imaginary part of soil dielectric constant to soil salt content (R=0.86), soil salt content determines the value of soil dielectric constant imaginary part. In the low frequency region, soil dielectric constant significantly correlated to the volumetric water content and soil salt content. In all frequency regions of studied electromagnetic wave, the real part of permittivity had a significant response to the soil volumetric water content, and it increased with the increasing of water content. As to the imaginary part of the permittivity, dielectric constant slightly increased with the decreasing of water content, which indicated the soil moisture directly determined the real part of soil dielectric constant. Imaginary part of the soil dielectric constant apparently responded to soil salinity, and the soil salt content obviously determined the imaginary part of the dielectric constant, especially in the lower frequency. We concluded that the corrective moist salt soil Dobson dielectric model can objectively describe the soil dielectric constant and the values estimated were approximate to the measured soil dielectric constant. This research showed that the soil dielectric constant can be used to monitor the degree of soil salt content, water content and soil salinization, and it is feasible to use the saline soil dielectric model to invert the soil salinity.
Number of references:18
Main heading:Arid regions
Controlled terms:Electromagnetic waves - Linear regression - Models - Permittivity - Remote sensing - Soil moisture - Soils
Uncontrolled terms:Arid and semi-arid regions - Arid area - Backscattering coefficients - Microwave remote sensing - Saline - Soil dielectric constant - Soil volumetric water contents - Volumetric water content
Classification code:902.1 Engineering Graphics - 731.1 Control Systems - 711 Electromagnetic Waves - 922.2 Mathematical Statistics - 701 Electricity and Magnetism - 444 Water Resources - 443 Meteorology - 483.1 Soils and Soil Mechanics
DOI:10.3969/j.issn.1002-6819.2013.16.016
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679256
Title:Analysis and experimental of centrifugal pump noise based on outlet width of impeller
Authors:Liu, Houlin (1); Ding, Jian (1); Tan, Minggao (1); Cui, Jianbao (1); Wang, Yong (1)
Author affiliation:(1) Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013, China
Corresponding author:Liu, H.(liuhoulin@ujs.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:66-73
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:In order to better understand the effects of impeller outlet width on the flow-induced vibration and noise of centrifugal pumps, a single grade end suction centrifugal pump was chosen as research object. The impeller outlet width was varied from 8mm to 10mm and 12mm, while the volute and other geometric parameters were kept constant. The flow-induced noise of centrifugal pumps was studied experimentally and numerically. A FEM\BEM acoustic-vibration-coupling method was developed to study the effect of impeller outlet width on the centrifugal pump noise caused by the hydrodynamic forces. The developed method was validated and verified through experimental results. For the internal flow of pumps characterized by a small Mach number, the sound analysis of fluid was separated into the following two steps. The first step was a hydrodynamic analysis, which is a CFD simulation to be performed to obtain noise-generating fluid forces; in this step, the large eddy simulation method was used to solve the transient flow field of the pump, and a time series for the pressure fluctuations at the fluid-wall interface was obtained. The second step was hydroacoustic-vibration coupling analysis, which considers the solution of an inhomogeneous wave equation. The fluid pressure fluctuations obtained at the first step are fed to the pump case structure causing vibration of the outer casing surface vibrating, based on the elastic-wave propagation of the structure, the vibration velocities on the outer casing surface was simulated. And the acoustical simulation of noise emission to the environment was performed by FEM\BEM methods, in which the feedback influences of environmental noise on the structure and of structural vibration on the fluid were considered. In the second step, the modal of the pump casing structure was analyzed using the finite element method (FEM), and the acoustic noise caused by the unsteady flow of the pump was calculated by the acoustic-vibro coupling module of the Virtual Lab software. First, the interior noise fields were calculated and compared with experimental results, showing that the validation of the LES combined with the FEM\BEM methods for centrifugal pump noise computation was verified, and the FEM\BEM coupling methods was more accurate than the BEM uncoupling methods. On this basis, the outer sound fields were investigated, and the effect of impeller outlet width to outer sound fields was studied. The results show that the sound power at the blade passing frequency becomes larger as the impeller outlet width increases. In order to investigate the sound spatial distribution around pump, 36 monitoring points were arranged each 1 meter farther from the center of impeller, and noise directivity distribution was obtained by using FEM\BEM calculations. The noise directivity results show that the sound pressure level at the blade passing frequency becomes larger as the impeller outlet width increases, and the growth amplitude of the sound pressure level increases as the impeller outlet width increases. Considering the energy performance of the pump and the outer sound field, there exists a suitable impeller outlet width to ensure a better comprehensive performance of the pump. The research results are helpful for hydraulic optimization design of low vibration and low noise centrifugal pumps.
Number of references:22
Main heading:Acoustic noise
Controlled terms:Acoustic field measurement - Acoustic fields - Acoustic wave transmission - Boundary element method - Centrifugal pumps - Computational fluid dynamics - Flow measurement - Hydrodynamics - Impellers - Large eddy simulation - Pumps - Structural dynamics - Wave propagation
Uncontrolled terms:Blade passing frequency - Comprehensive performance - Flow induced vibrations - Hydraulic optimizations - Impeller outlet - Inhomogeneous wave equations - Large Eddy simulation methods - Vibrations
Classification code:921 Mathematics - 751 Acoustics, Noise. Sound - 711 Electromagnetic Waves - 921.6 Numerical Methods - 631 Fluid Flow - 601.2 Machine Components - 408 Structural Design - 618.2 Pumps
DOI:10.3969/j.issn.1002-6819.2013.16.009
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679259
Title:Experimental study on Morgan model under waterlogging stress
Authors:Qian, Long (1); Wang, Xiugui (1); Luo, Wenbing (1); Wu, Lin (1)
Author affiliation:(1) State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
Corresponding author:Wang, X.(wangxg@whu.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:92-101
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:The crop water production function under waterlogging stress is of significance both for the benefit evaluation of disaster reduction and the decision making of waterlogging disaster control. Crop water production functions can be categorized into two kinds: dynamic model and static model. Since the dynamic models were based on a certain crop physiology basis, it can be used to simulate the process of crop growth. However, the dynamic models under waterlogging were rarely found in publications. Based on the Morgan model, which was originally used for crop yield simulation under water deficit, this paper established a revised Morgan model for waterlogging stress by replacing the soil moisture index with waterlogging indexes. The waterlogging indexes widely used in practice were subsurface-surface separated index (SEW<inf>30</inf>, SFW) and composite index SFEW<inf>30</inf>. But the former had a problem that the weight of surface waterlogging index was too small compared with subsurface waterlogging index. To balance the weight of subsurface and surface waterlogging indexes, the separated indexes were divided by time such as (SEW<inf>30</inf>, SWFDH) and space such as (SEW<inf>30</inf>, SFW) respectively. All the three different waterlogging indexes i.e. (SEW<inf>30</inf>, SFW), (SEW<inf>30</inf>, SWFDH), SFEW<inf>30</inf> were used to revise the Morgan model in order to obtain the most suitable index. Waterlogging experiments on cotton were carried out in 22 lysimeters at Irrigation and Drainage Comprehensive Experimental Station in Wuhan University from 2008 to 2011. Dry matter yield samples were taken every 10 days, and the dynamic change of groundwater table was monitored every day during the period of waterlogging. Data in 2009 and 2010 were used to calibrate parameters and the data in 2008 and 2011 were used to validate the revised Morgan model. Results showed that the cotton dry matter yields predicted by the revised Morgan model adopting three different indexes all coincided with the observed yields well, especially the indexes (SEW<inf>30</inf>, SFW) and (SFEW<inf>30</inf>). The corresponding revised Morgan model adopting the two indexes both achieved a high significance level of 0.001 in both 2008 and 2011 with a smaller relative error of less than 20%, which showed that, the revised Morgan model was effective and practicable for cotton dry matter yields simulation under waterlogging stress. Considering the less amount of parameters in model and precision, the composite index (SFEW<inf>30</inf>) was recommended to adopt in the revised Morgan model preferentially, but only by adopting the index (SEW<inf>30</inf>, SFW), the effect of subsurface and surface waterlogging on dry matter yields can be analyzed respectively. In order to make a comparison between the revised Morgan model and the static model, both of them were calibrated and validated with the same data obtained from the waterlogging experiments, and the simulated yields of both of the two models were compared with the observed yields. Results showed that the prediction of the revised Morgan model both an acceptable significant level of 0.05 in 2011 and a relative small relative error of less than 20% in 2008 while the static model failed to achieve these error indexes, which indicated that the revised Morgan model had a better stability than the static model in different years.
Number of references:18
Main heading:Computer simulation
Controlled terms:Cotton - Crops - Disasters - Dynamic models - Dynamics - Experiments - Groundwater - Models - Soil moisture - Stresses
Uncontrolled terms:Crop water production function - Crop yield simulations - Disaster reduction - Experimental stations - Morgan models - Significance levels - Soil moisture index - Waterlogging
Classification code:921 Mathematics - 902.1 Engineering Graphics - 901.3 Engineering Research - 821.4 Agricultural Products - 931.1 Mechanics - 723.5 Computer Applications - 483.1 Soils and Soil Mechanics - 444.2 Groundwater - 421 Strength of Building Materials; Mechanical Properties - 484 Seismology
DOI:10.3969/j.issn.1002-6819.2013.16.012
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679255
Title:Numerical simulation and analysis on whole flow field for drip self-cleaning screen filter
Authors:Zong, Quanli (1); Zheng, Tiegang (3); Liu, Huanfang (1); Li, Qiangqiang (1); Zheng, Huaping (4)
Author affiliation:(1) College of Water Conservancy and Architectural Engineering, Shihezi University, Shihezi 832000, China; (2) State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China; (3) China Institute of Water Resources and Hydropower Research, Beijing 100038, China; (4) Shihezi Jintudi Water Saving Equipment Company Limited, Shihezi 832000, China
Corresponding author:Zheng, T.(hydraulic_ztg@126.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:57-65
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:A self-cleaning screen filter has broad application on the domestic and foreign markets. The variation law of head loss, and the relationship between filtering time and self-cleaning time have been analyzed through different experiments. However, the flow distribution of filter inside cannot be obtained by traditional experiment methods. To fully understand the internal flow structure and characteristics of a self-cleaning screen filter and find the inadequacies of flow field distribution, the whole flow was simulated through Fluent (6.3). Based on the analysis of filter structure and self-cleaning principle, the mathematical model of inside flow field and the dynamic grid model of a self-cleaning system were established respectively, the computing area and the grid of filtering and self-cleaning processes, as well as boundary condition of inlet and outlet were proposed. In order to ensure the reliability of the simulation results, the relationship between the flow rate and pressure of a self-cleaning system were compared in this study, and the results show that the simulated pressure agreed with the measured values. The internal flow field of the filtering process was simulated, and the distribution law of flow velocity, turbulent energy, and average pressure were studied. The flow velocity decreases along the radial direction of the filter body, and it decreases rapidly from the inlet value of 2.6~3.0 m/s to the outlet value of 1.4~1.8m/s. The maximum average pressure was located at the inlet of flow, and the average pressure of the first filtering chamber was significantly higher than the value of the second filtering chamber, which the average pressure reduces relatively 25% and 80% after the flow passes the first and second filtering chambers. As the distributions of flow and turbulent energy are extremely uneven, the clogging of the entire screen is uneven. The design of inlet and outlet should be changed in order to avoid the uneven clogging of the entire screen, for example, several small-diameter screens replace a big diameter-screen. Moreover, through the technology of dynamic mesh, the process of self-cleaning was also simulated, and the flow fields of flow velocity, turbulent energy and average pressure were analyzed. The inlet of sunction will have a huge attractive power, which can ensure that the sediment of the screen surface be cleaned. But the velocity, average pressure, and turbulent energy of sunction vary greatly at different heights of sunction. The maximum and minimum values of velocity are located respectively at upper and lower sunction, and the maximum velocity difference is about 8.5m/s, which results in the lower screen being cleaned unthoroughly and the upper screen being damaged easily. The pressure gradient near the sunction is large, and the maximum pressure difference between outside and inside the sunction is about 1.1MPa. The maximum and minimum values of average pressure are located respectively at middle and upper sunction, which results in different cleaning efficiency at different heights of sunction. The maximum average value of turbulent energy is located at lower sunction, and a local high turbulent energy area also appeared at upper sunction. The simulated results of a self-cleaning system indicate that the distribution of sunction tubes can not be uniform along the axial direction, and the position of suction tubes can be adjusted and the number can be increased, which can increase the sunction power of lower sunction tubes and improve the cleaning efficiency of sediment.
Number of references:22
Main heading:Cleaning
Controlled terms:Computer simulation - Experiments - Flow fields - Flow velocity - Inlet flow - Irrigation - Mathematical models - Numerical analysis - Tubes (components)
Uncontrolled terms:Cleaning efficiency - Flow field distribution - Folw field - Internal flow field - Internal flow structure - Screen filters - Self-cleaning process - Simulation and analysis
Classification code:921.6 Numerical Methods - 921 Mathematics - 901.3 Engineering Research - 821.3 Agricultural Methods - 802.3 Chemical Operations - 723.5 Computer Applications - 631.1 Fluid Flow, General - 631 Fluid Flow - 616.1 Heat Exchange Equipment and Components
DOI:10.3969/j.issn.1002-6819.2013.16.008
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679250
Title:Design and experiment of transverse-feeding ramie decorticator
Authors:Lü, Jiangnan (1); Long, Chaohai (1); Zhao, Ju (2); Ma, Lan (1); Lü, Hongbing (2); Liu, Jiajie (1); He, Hongbin (1)
Author affiliation:(1) Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China; (2) Hongze Textile Machinery CO., LED, Hongze 223100, China
Corresponding author:Lü, J.(yjljn@sina.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:16-21
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Ramie fiber is a type of natural fiber that has long history in civilization. It plays a very important role in Chinese textile process industry. With characteristics of good tensile strength, excellent ventilation, quickly water absorption and volatilization and well corrosion, ramie fiber is prevalent as textile material of making shirt, western-style clothes, T- shirts, underwears health socks, summer beddings and summer sleeping mats. Ramie, as a kind of bast fiber crop, its bast is difficult to be separated from the ramie stem. Therefore, ramie harvesting and fiber peeling cost heavy money and plenty of time. Until present days, people still use the manual decorticator and small-sized motor decorticator to peel ramie fiber in China. These methods are of high cost and intense manual labor, thus China is still far away from solving the difficulty in peeling ramie fiber. Small-sized motor decorticator and simple manual decorticator have been used for peeling ramie fiber in China. Due to the lower production capacity, they can not meet the demands of ramie fiber harvesting in time in large-scale cultivated area. In order to solve the problems of high labor intensity and low efficiency of ramie fiber decortication, high efficiency ramie decorticator was developed. This new ramie decorticator discards old traditional method of processing ramie. With this machine, we designed double peeling cylinders located at both inside and outside of the grip chain to segmentally process the bottom and top of full ramie stems, and transverse fed the stems of ramie, which greatly improved the efficiency of ramie decortication. This high efficiency ramie decorticator implemented mechanization of ramie stem feeding, peeling, fiber water washing and collection. We produced the first transverse feed ramie decorticator, carried out experiments on sample machine and launched the quality test of decorticated fiber. Since this machine can reduce the auxiliaries working time and process ramie stem continuously, it enhances the productivity substantially. Experiment results showed that productivity of this machine was 131kg/h, which was 19 times as much as small-sized motor decorticator, and fiber percentage of fresh ramie stem was 4.15%, which basically reached the design requirement. According to the sample test analysis, the percentage of ramie impurities content was 1.09%, which was lower than that of the second level ramie impurities content (1.5%); the rubber content of ramie was 23.28%, which was lower than that of the required standard of machine decorticated ramie (&le28%); and the breaking strength of ramie bundle was 4.59 cN /dtex, which exceeded that of the first level degummed ramie (≥4.50 cN/dtex) set by national standard. All these data showed that the quality of fiber decorticated by the sample decorticator meet the requirements of textile enterprises. This ramie decorticator with high efficiency and high (stable) fiber quality is suitable for large-scale ramie base.
Number of references:22
Main heading:Hemp
Controlled terms:Agricultural machinery - Bark stripping - Efficiency - Experiments - Feeding - Fibers - Productivity - Tensile strength - Textile industry - Textiles
Uncontrolled terms:Breaking strength - Impurities contents - Method of processing - National standard - Process industries - Production capacity - Ramie - Textile enterprise
Classification code:913.1 Production Engineering - 901.3 Engineering Research - 821.4 Agricultural Products - 821.1 Agricultural Machinery and Equipment - 819 Synthetic and Natural Fibers; Textile Technology - 817 Plastics and Other Polymers: Products and Applications - 812 Ceramics, Refractories and Glass - 811.2 Wood and Wood Products - 691.2 Materials Handling Methods - 422 Strength of Building Materials; Test Equipment and Methods - 421 Strength of Building Materials; Mechanical Properties
DOI:10.3969/j.issn.1002-6819.2013.16.003
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679249
Title:Design and testing of head-stem segregation equipment for garlic
Authors:Yu, Zhaoyang (1); Hu, Zhichao (1); Wang, Haiou (1); Peng, Baoliang (1); Xie, Huanxiong (1); Wu, Feng (1)
Author affiliation:(1) Nanjing Research Institute of Agricultural Mechanization, Ministry of Agriculture, Nanjing 210014, China
Corresponding author:Hu, Z.(nfzhongzi@163.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:7-15
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Garlic is one of the major cash crops in China. Production, acreage, and exports of garlic in China are the highest in the world. As a seasonal operation, garlic harvesting in China is still mainly manual work, having the problems of low efficiency, high labor intensity, and huge occupation of farming season, which has constrained the further development of the garlic industry. The current domestic garlic harvesters are basically simple segmented machinery. The techniques of garlic combine harvesting is still in its infancy. Picking is the core technology on garlic combine harvesting, but it has not been refined well. In order to enhance operational performance of picking, a new kind of garlic picking testbed was designed to carry out the studies on optimization design on structural and working parameters of a garlic-picking device. Lower damage and less stem are the two primary objectives in garlic harvesting. The garlic picking testbed consists of a clamping delivery device, a ranking/alignment device, a cutter, and an electric control system, which carry out garlic clamping, transport, ranking, alignment, and cutting at one time. The clamping delivery device of which core components are front track and middle track uses two tooth-shaped chains. Through the guidance of the two tracks, the trajectory and clamping style of the chains is changed, achieveing the transition from double chain clamping to chain-board-hairbrush clamping, The core components of the ranking/alignment devices are guidance rods, a ranking disk, finger, an alignment chain, and a hairbrush. In the test, the garlic was artificially fed. First, garlic plants are gripped by the clamping delivery device and transported backward. Under the interaction of ranking/alignment devices and clamping/delivery devices, garlic plants are ranked automatically and garlic bulbs are aligned automatically. After the garlic bulbs are aligned, garlic stems are cut by disc cutters to achieve garlic bulbs whose stems are consistent and much shorter. The method of alignment is that garlic bulbs are forced to pull down by the rank/alignment devices. This paper mainly studied the structural and working principles of clamping/delivery devices, ranking/alignment devices, and the finger of garlic-picking testbed, optimally selecting the position and speed data between the clamping/delivery device and the ranking/alignment device. When the speed ratio is 1.02 between the two components, the cut face of the stem is perpendicular to garlic stem. Through use of the testbed, the relationships among clamping height, clamping angle, speed of main clamping chain with picking performance indexes were optimized. Primary & secondary factors and the significance level of the influence on the picking performance indexes were analyzed. Utilizing a fuzzy comprehensive evaluation method, the combination of optimum parameters was determined. The results show that the optimum parameters include a clamping height of 190mm, a clamping angle of 79°, and a chain speed of 1.06 m/s for the main clamping chain. When the optimum parameters are used, the residual stem length is 37.56 mm, and the damage rate is 2.33%. The research results provided a theoretical design basis for a garlic-picking device on a combine harvester.
Number of references:27
Main heading:Chains
Controlled terms:Agricultural machinery - Combines - Design - Harvesters - Harvesting - International trade - Separators - Structural optimization - Testbeds
Uncontrolled terms:Electric control system - Fuzzy comprehensive evaluation method - Garlic - Operational performance - Optimization design - Performance indices - Semi-feeding - Significance levels
Classification code:902.3 Legal Aspects - 821.3 Agricultural Methods - 821.1 Agricultural Machinery and Equipment - 921.5 Optimization Techniques - 802.1 Chemical Plants and Equipment - 602.1 Mechanical Drives - 408 Structural Design - 723.5 Computer Applications
DOI:10.3969/j.issn.1002-6819.2013.16.002
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679273
Title:Application of cogeneration technology of gas-liquid-solid products pyrolyzed from crop straw
Authors:Liu, Biao (1); Chen, Yingquan (1); He, Tao (2); Yang, Haiping (1); Wang, Xianhua (1); Chen, Hanping (1)
Author affiliation:(1) State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China; (2) Wuhan Tianying Environmental Engineering Co., Ltd., Wuhan 430074, China
Corresponding author:Yang, H.(yhping2002@163.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:213-219
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:To improve the standard of living in rural areas, many distributed gas stations were constructed in Hubei province, and these stations were based on the biomass-polygeneration technology which could produce charcoal, fuel gas and bio-oil simultaneously. This paper presented a theoperational process and the character of products of a typical station. The gas station consisted of a biomass pretreatment system, retort equipment, condensation and purification system, gas storage tank, and pipeline. At first, agricultural straws were dried until their moisture content was below 12%. Subsequently, the dried straws were briquetted, and these briquettes were placed in an orderly manner in the retort equipment. The fuel gas or straws were combusted to supply heat for the pyrolysis process of the briquettes. A complete pyrolysis process would take above 8 hours. At the beginning of 2-3 hours, a large amount of water was formed from external water and bound water when the temperature was controlled below 250°C. At this stage, the gas product consisted of CO<inf>2</inf>, CO, and water vapor, and the heat value was rather lower, therefore, these gases would combust. After the gas product was heated about 5~6 hours, the temperature of the retort was up to 600°C, then, the straw briquettes degraded rapidly, and a large amount of volatiles generated which would be removed from the retort equipment to a condensation and purification system. Simultaneously, charcoal was formed and the residue volume was only 30% to 40% of the original briquette because of the released volatiles. At the last 2-3 hours, the retort was retained at 600°C, then the charcoal would be further upgraded and a small amount of liquid product and gaseous products would be generated. The temperature of fresh volatiles out of the retort was up to 450°C, and then these fresh volatiles would cool down to room temperature by condensation and purification. The bio-oil and fuel gas were separated from the volatiles, and the bio-oil was further separated into wood tar and wood vinegar that was stored in the liquid tanks. The fuel gas was stored in a gas storage tank and transferred to users by pipeline. Charcoal was naturally cooled to 60-80°C in a retort and then collected to package and place in storage. For biomass-polygeneration technology, 1 ton agricultural straws can produce 230-310 m3 of fuel gas, 250-300kg of charcoal, 50 kg of wood tar, and 250 kg of wood vinegar. The main components of fuel gas are CO, CO<inf>2</inf>, H<inf>2</inf>, CH<inf>4</inf>, and other incondensable light hydrocarbons, such as C<inf>2</inf>H<inf>2</inf>, C<inf>2</inf>H<inf>4</inf>, C<inf>2</inf>H<inf>6</inf>, and so on, and its heat value (LHV) reaches to 12 MJ/m3 due to the volume fraction of hydrogen and methane being up to 25% and 18%, respectively. The characteristics of charcoal are similar to anthracite, which has a small volatile content and high fixed carbon, and the heat value (LHV) is around 28 MJ/kg. The porosity of charcoal is well developed, and can be used as an industrial adsorbent and soil conditioner. The yield of wood tar is generally from 4.5% to 7%, and wood tar is composed of a large amount of macromolecules, such as anthracene, naphthalene, and some 10 carbon aliphatic chain hydrocarbon. Wood vinegar has high water content, more than 85%, and the organic component is composed of acetic acid and a small amount of phenol. Meanwhile, this paper analyzed the economic benefits of the typical gas station. It found that the sharp rise of electricity and labor costs reduces the economic benefits of the station.
Number of references:26
Main heading:Air purification
Controlled terms:Acetic acid - Biofuels - Biomass - Briquets - Carbon dioxide - Charcoal - Condensation - Crops - Equipment - Gases - Hydrocarbon refining - Liquids - Methane - Naphthalene - Pipelines - Pyrolysis - Rural areas - Straw - Tanks (containers) - Tar - Wages
Uncontrolled terms:Biomass pre treatments - Case analysis - Cogeneration technologies - Economic benefits - Gas supply system - High water content - Organic components - Purification systems
Classification code:931.2 Physical Properties of Gases, Liquids and Solids - 911.1 Cost Accounting - 901 Engineering Profession - 821 Agricultural Equipment and Methods; Vegetation and Pest Control - 804.2 Inorganic Compounds - 804.1 Organic Compounds - 802.3 Chemical Operations - 802.2 Chemical Reactions - 672 Naval Vessels - 643 Space Heating, Ventilation and Air Conditioning - 619.2 Tanks - 619.1 Pipe, Piping and Pipelines - 524 Solid Fuels
DOI:10.3969/j.issn.1002-6819.2013.16.027
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679251
Title:Design and experiment of automatic mixing apparatus for liquid fertilizer based on fuzzy control
Authors:Li, Jianian (1); Hong, Tiansheng (2); Feng, Ruijue (2); Ni, Huina (2)
Author affiliation:(1) Faculty of Modern Agricultural Engineering, Kunming University of Science and Technology, Kunming 650500, China; (2) College of Engineering, South China Agricultural University, Guangzhou 510642, China; (3) Key Laboratory of Key Technology on Agricultural Machine and Equipment, Ministry of Education, Guangzhou 510642, China; (4) Division of Citrus Machinery, China Agriculture Research System, Guangzhou 510642, China; (5) Guangzhou College of South China University of Technology, Guangzhou 510800, China
Corresponding author:Hong, T.(tshong@scau.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:22-30
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Fertigation is an irrigation technology of integration of water and fertilizer, and has been widely used in micro-irrigation systems, because of uniform fertilization, high utilization of water and fertilizer, and effectively reducing the pollution of soil and environment. The venturi fertilizer injector has become one of the main means and important equipment to achieve fertigation due to its simple structure, economy, and practicability, but the liquid fertilizer concentration could not be easily adjusted automatically. In order to realize variable rate fertilization with a venturi fertilizer injector, a variable fertilizer apparatus based on PWM (pulse width modulation) technology has been developed, but the apparatus belongs to open-loop control from the perspective of automatic control, and its accuracy and stability is difficult to guarantee. Therefore, a closed-loop control automatic fertilizer-mixing device was developed to improve the liquid fertilizer concentration mixing accuracy and stability, by improving the structure of the variable fertilizer apparatus and adding a conductivity meter that was employed to feedback the real-time fertilizer solution concentration indirectly. The conductivity meter was designed based on a conductivity electrode, and a square signal whose amplitude is ±3.5 V was determined as the excitation signal of the conductivity meter through experiments, to weaken or even eliminate polarization effects and capacitance effects of the conductivity electrode in the measuring process. In order to further improve measuring accuracy, temperature compensation had been applied to the conductivity meter, the measuring range had been divided into several small-scale ranges which could be switched by a multiplexer ADG1408 controlled by a microcontroller, and the corresponding divider resistor and square signal frequency of each small scale range were determined by experiments. By comparison with a standard conductivity meter, whose model is sension 156, the effective measuring range of the conductivity meter designed was 0-12.64 mS/cm, and the conductivity meter designed was calibrated according to the data measured in the effective measuring range. It was known that the conductivity of the fertilizer solution measured by the conductivity meter has a significant linear relationship (the coefficient of determination R2 is 0.997) with the fertilizer solution concentration, based on conductivity testing of a series of different concentration fertilizer solutions prepared in the range of 0.1%-1.0%. In order to improve the control performance of the automatic fertilizer mixing device, a kind of control strategy of two-step regulating with coarse adjustment and fine adjustment was employed: first, the device adjusted the duty cycle of PWM for controlling the solenoid valve to mix fertilizer automatically, by calling the corresponding function based on the detected inlet water pressure; then the device uses a fuzzy control algorithm to regulate the duty cycle of PWM finely, according to the real-time fertilizer solution concentration measured by the designed conductivity meter, in order to make the mixed fertilizer concentration get close to the target concentration as much as possible. An actual test and verification had been undertaken for the fertilizer mixing device, and the results showed that the maximum error of the mixed fertilizer concentration was 0.04% and the response time of the control device for achieving steady-state was 7.8-10.4 s, and it is now known that the device can meet the requirements of practical application in agriculture.
Number of references:31
Main heading:Fertilizers
Controlled terms:Agriculture - Algorithms - Automation - Control - Electric conductivity - Experiments - Fuzzy control - Mixing - Pulse width modulation - Solutions - Water pollution
Uncontrolled terms:Coefficient of determination - Comparison with a standard - Integration of water and fertilizers - Microirrigation systems - Solution concentration - Target concentrations - Temperature compensation - Variable rate fertilization
Classification code:921 Mathematics - 901.3 Engineering Research - 821 Agricultural Equipment and Methods; Vegetation and Pest Control - 804 Chemical Products Generally - 803 Chemical Agents and Basic Industrial Chemicals - 802.3 Chemical Operations - 801 Chemistry - 732 Control Devices - 731 Automatic Control Principles and Applications - 723 Computer Software, Data Handling and Applications - 716 Telecommunication; Radar, Radio and Television - 701.1 Electricity: Basic Concepts and Phenomena - 453 Water Pollution
DOI:10.3969/j.issn.1002-6819.2013.16.004
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679275
Title:Exploitation suitability evaluation and potential area zoning for arable unused land in mountainous areas of Yunnan province
Authors:Yuan, Lei (1); Zhao, Junsan (1); Li, Hongbo (1); Zhang, Meng (1); Chen, Guoping (1); Guo, Xiaohui (1)
Author affiliation:(1) Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China; (2) Kunming Yunjindi Ceo-information Co., Ltd., Kunming 650106, China; (3) Faculty of Architecture and Civil Engineering, Kunming University of Science and Technology, Kunming 650500, China; (4) Faculty of Surveying and Mapping, Kunming Metallurgy College, Kunming 650033, China
Corresponding author:Zhao, J.(junsanzhao@netease.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:229-237
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Unused land is the major reserve resource of cultivated land in China. But the quality of the unused land is generally relatively poor in many provinces. Because of the poor quality and complexity of explotation for the unused land, the difficulty of exploitation is often relatively large. This is especially true in the mountainous areas of Yunnan province, where there is an undulating terrain, and severe cutting or tearing action. Therefore, geoscience factors show significant spatial differentiation in the province. As a result, exploitation of unused land in Yunnan province is different from others. In order to guide a better space-time configuration of the exploitation for arable unused land in the province, exploitation suitability evaluation and potential area partition for the arable unused land is researched in this paper which focuses in a typical mountainous area county of Yunnan province which is named Midu for example. Based on combining spatial analysis techniques of the Geographical Information System (GIS), the Analytical Hierarchy Process (AHP), and the Delphi method, this study constructed the suitability evaluation for exploitation of the arable unused land model, the new land indices and additional land potential model, and the evaluation of the partition for potential area of the arable unused land model respectively. Then it was analyzed the exploitation suitability and partition of the potential area of the arable unused land in the mountain area of Yunnan province. The results show that the exploitation suitability of the unused land includes four grades which are the most suitability area, the medium suitability area, the barely suitability area, and the unfit area. The area of them is 71.21 hectares, 1177.39 hectares, 1681.00 hectares, and 62.00 hectares respectively, and accounts for 2.38%, 39.36%, 56.19% and 2.07% of the total area of the study area separately. The actual exploitation potential of the unused land in study area is 1248.60 hectares, and among them there are 977.45 hectares excepted to develop into cultivated land. The result of the partition is indicated so that the study area could be divided in five potential areas and one non-potential area. Among these areas, the actual exploitation potential from one-level to five-level are 164.97 hectares, 53.38 hectares, 210.64 hectares, 773.93 hectares, and 45.68 hectares respectively. The potential of additional cultivated land are 144.21 hectares, 46.66 hectares, 164.01 hectares, 590.11 hectares, and 32.46 hectares respectively. The application of the research results show that the suitability evaluation results, cultivated land estimation results, and potential partition results are consistent with the local circumstances.
Number of references:28
Main heading:Agriculture
Controlled terms:Geographic information systems - Land use - Models - Zoning
Uncontrolled terms:Analytical Hierarchy Process - Estimation results - Exploitation potentials - Midu county - Research results - Spatial analysis - Spatial differentiation - Suitability evaluation
Classification code:403 Urban and Regional Planning and Development - 723.3 Database Systems - 821 Agricultural Equipment and Methods; Vegetation and Pest Control - 902.1 Engineering Graphics
DOI:10.3969/j.issn.1002-6819.2013.16.029
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679281
Title:Weibull distribution for modeling drying of grapes and its application
Authors:Bai, Junwen (1); Wang, Jiliang (2); Xiao, Hongwei (1); Ju, Haoyu (1); Liu, Yanhong (1); Gao, Zhenjiang (1)
Author affiliation:(1) College of Engineering, China Agricultural University, Beijing 100083, China; (2) Institute of Agricultural Products Processing, Xinjiang Academy of Agricultural and Reclamation Science, Shihezi 832000, China
Corresponding author:Gao, Z.(zjgao@cau.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:278-285
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Grapes as a seasonal fruit, have relatively high sugar content and moisture content, and are very sensitive to microbial spoilage during storage. Therefore, grapes once harvested must be consumed or processed into various products within a few weeks in order to reduce economic losses. Drying grapes into raisins is the major processing method in almost all countries where grapes are grown. The knowledge of the drying mechanism is very necessary for heat and moisture transportation efficiency, energy savings and product quality. Several different empirical and semi-empirical drying models were used for describing and predicting drying curves. Some of these models could give a good fit to the drying curves, but the basic idea of process characterization was to consider the process as a "black box"-the drying materials and drying conditions were difficult to be related to the parameters of these models used. In this study, the Weibull distribution model was applied to the drying process under different drying methods (hot air drying, pulsed vacuum drying), drying temperature (50, 55, 60and 65°C) and blanching pretreatment time (0, 30, 60, 90, 120 s). The result demonstrated that the Weibull distribution model could well describe the drying curves, for the moisture ratio vs. drying time profiled of the model showed high correlation coefficient (R2=0.993-1.000), and low root mean squared error (RMSE=2.72×10-3-2.12×10-2) and chi-squared (χ2 = 8.13×10-6-4.27×10-4). For the drying process, the scale parameter (α) defined the rate constant and represented the time needed to accomplish approximately 63% of the process. It was found that the scale parameter (α) was depending on the drying temperature and the drying method. When the drying temperature increased from 50 to 65°C, the scale parameter (α) decreased from 2738.946 to 840.846 min for hot air drying and decreased from 813.219 to 294.831 min for pulsed vacuum drying, respectively. The blanching time could also affect the scale parameter (α), the value of α was decreased from 840.846 to 133.754 with the blanching time increased from 0 s to 120 s at drying temperature of 65°C. The shape parameter (β) was related to rate of the mass transfer at the beginning of drying. In this study, it was found that the shape parameter (β) was depending on the drying method and materials status. For the same drying method, drying temperature had little impact on the shape parameter (β=1.214-1.258 for hot air drying, 1.393-1.409 for pulsed vacuum drying). One important application of the Weibull distribution model is to determine the moisture diffusion coefficient (D<inf>cal</inf>), whether the whole drying occurs in the falling rate period or not, by the scale parameter (α). So the D<inf>cal</inf> of the grape samples were calculated, ranging from 0.2982×10-9 to 2.7700×10-9 m2&middots-1, and it was found that increasing drying temperature, increasing blanching treatment time could enhance the D<inf>cal</inf> of grape samples. The activation energy for moisture diffusion of grape samples was 72.87 and 61.43 kJ/mol by hot air drying and pulsed vacuum drying, respectively. It was demonstrated that drying method can affect the activation energy, and drying grapes with pulsed vacuum could save energy and increase efficiency. The result will provide a reference for the application of Weibull distribution on grape drying.
Number of references:29
Main heading:Drying
Controlled terms:Activation energy - Blanching - Diffusion - Losses - Models - Moisture - Rate constants - Temperature - Vacuum - Weibull distribution
Uncontrolled terms:Correlation coefficient - Falling-rate period - Grapes - Microbial spoilage - Moisture diffusion coefficient - Process characterization - Root mean squared errors - Transportation efficiency
Classification code:931.1 Mechanics - 922.2 Mathematical Statistics - 911.2 Industrial Economics - 902.1 Engineering Graphics - 931.3 Atomic and Molecular Physics - 822.2 Food Processing Operations - 642.1 Process Heating - 641.1 Thermodynamics - 633 Vacuum Technology - 801.4 Physical Chemistry
DOI:10.3969/j.issn.1002-6819.2013.16.035
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679267
Title:Color image segmentation of plant lesion using improved C-V model based on Gaussian distribution
Authors:Tian, Jie (1); Hu, Qiuxia (1); Ma, Xiaoyi (3)
Author affiliation:(1) College of Mechanical and Electronic Engineering, Northwest A and F University, Yangling 712100, China; (2) College of Information Engineering, Northwest A and F University, Yangling 712100, China; (3) College of Water Resources and Architecture Engineering, Northwest A and F University, Yangling 712100, China
Corresponding author:Ma, X.(xiaoyimasl@yahoo.com.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:166-173
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:In order to make the C-V model segment plant lesion images more accurate and display quicker, the Gaussian mix model was introduced to set up an improved C-V model in this paper. In view of the drawbacks of long processing time and determining the R, G, B channel energy coefficients artificially for the weighted color information-based C-V model, an improved C-V model based on a Gaussian mix model was proposed in this paper and applied to plant lesion image segmentation. At first, a point in the lesion area was selected and the averages over its 3×3 neighbor was taken as the internal energy in the C-V model. Then the Gaussian mix model was used to model the image, and the sign distance function was initialized by prior probability. Finally, the ratios of the averages on the foreground and background from R, G, B channels were used as the weights of these three channels respectively, and the level set function was iterated to obtain the segmentation contour. To verify the improved C-V model for plant lesion color image segmentation, the traditional C-V model and the weighted color information-based C-V model were used as counterpart algorithms in term of quantitative evaluation of image segmentation, respectively. The experimental results were the averages over ten experiments. In every experiment, two important things had to be decided: one was that the selected point must fall into larger lesion areas, the other was that the Gaussian mix model was calculated by the EM method. The experimental results and analysis on capsicum lesion image and cucumber lesion image mainly lay in the following three aspects. First, for the noised slightly capsicum lesion images, the undetected ratio and the over detected ratio of segmentation for the proposed method were 0.02 lower and 0.01 higher than that of the weighted color information-based C-V model, respectively. For the larger pixels cucumber lesion images, the undetected ratio was about equal to and the over detected ratio was 1.7 lower than that of the weighted color information-based C-V model. The traditional C-V model had the minimum undetected ratio and the maximum over detected ratio. The running time of the proposed method in segmenting capsicum and cucumber lesion images was less than that of the weighted color information-based C-V model and that of the traditional C-V model. Secondly, by making use of the ratios of the averages on foreground and background from R, G, B channels as the weights of these three channels respectively, not only was the contrast between lesion area and background area stressed, but also the randomness to artificially compute the weights through many trials in weighted color information-based C-V model was reduced. Thirdly, the proportion of the target pixels in the entire image was utilized as the final weights of image energy, which decreased the possibility of over-segmentation. Above all, the proposed method in this paper obtained better performance than the weighted color information-based C-V model and the traditional C-V model. Therefore, the algorithm based on C-V and Gaussian mix model provides an effective means to separate the lesions in an image.
Number of references:23
Main heading:Image segmentation
Controlled terms:Algorithms - C (programming language) - Color - Crops - Experiments - Gaussian distribution - Image processing - Models - Pixels
Uncontrolled terms:Better performance - C-v models - Color image segmentation - Gaussian Mixture Model - Internal energies - Level Set - Level set functions - Quantitative evaluation
Classification code:921 Mathematics - 902.1 Engineering Graphics - 901.3 Engineering Research - 922.1 Probability Theory - 821.4 Agricultural Products - 741 Light, Optics and Optical Devices - 723 Computer Software, Data Handling and Applications - 741.1 Light/Optics
DOI:10.3969/j.issn.1002-6819.2013.16.021
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679254
Title:Thermogravimetric characteristics analysis of particulate matter of emission of divided diesel
Authors:Mei, Deqing (1); Zhao, Xiang (1); Wang, Shulong (1); Yuan, Yinnan (2); Sun, Ping (1)
Author affiliation:(1) School of Automotive and Traffic Engineering, Jiangsu University, Zhenjiang 212013, China; (2) School of Mechanical Engineering, Nantong University, Nantong 226019, China
Corresponding author:Mei, D.(meideqing@ujs.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:50-56
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Particulate matter (PM), which contains soluble organic fraction (SOF), soot and inorganic salt, has been one of the main pollutions from diesel engine. Longtime exposure to the particulate matters especially those smaller than 2.5 micrometers (PM2.5) which can go directly to the alveoli of the lungs, is a major health hazard. In addition, many studies have revealed that the particles of smaller size would bring about greater harm to the human body. Due to the potential health risk in urban areas, the elimination of fine and ultrafine particulates emissions from diesel engine has attracted much attention in recent years. Meanwhile, the strict regulations for PM emission have been enforced in many developed countries. The micro-orifice uniform deposition impactor (MOUDI) is a favorable apparatus for measuring particles size distribution of atmospheric aerosol base on aerodynamic method. It can not only obtain the particle size distribution but also collect the particles in the different size ranges after classification, which extremely facilitates further research for chemical components, microstructure, oxidation characteristic and biological toxicity of the divided particle samples. Thermogravimetric analysis (TGA) has been widely used as an analytical method for kinetic of chemical reactions. Thermal gravimetric analysis means to investigate the relationship between the material weight and temperature under the condition of programming temperature rise. The curve of sample weight then can be obtained with the temperature. Derivative thermal gravimetry (DTG) curve, the first order differential to TG curve, can reveal the features of mass variation with the temperature. To study the ignition and oxidation properties of particulates, thermogravimetric method would be an effectual option. The particulates collected by MOUDI were divided into four size ranges which were 0.18 ~ 0.32μm, 0.32 ~ 0.56μm, 0.56 ~ 1.0μm and 1.0~1.8μm Thermogravimetric experiments on the divided particulates were carried out in the atmosphere of N<inf>2</inf> and then O<inf>2</inf>. The experimental results showed that the moisture and SOF contents in PM increased with the increase of particle size, while the soot and inorganic salt contents decreased conversely. During the SOF volatilation phase in the atmosphere of N<inf>2</inf>, the SOF content and the peak weight loss rate of particles decreased with the decrease of particle size. However, the weight loss rates of the divided particles converged during the soot pyrolysis phase. At the end of programmed temperature rise, the TG curves of particles of each size in N<inf>2</inf> atmosphere slowly stopped at various positions, while those were almost overlapping in O<inf>2</inf> atmosphere. With the decrease of particle size, the TG curves showed an apparent downward trend, which means the smaller the particle size was the easier the losing of weight was due to heating or including oxidation. In O<inf>2</inf> atmosphere, the derivative thermal gravimetry (DTG) curves of different sizes of particles in the SOF volatilation phase were consistent with those in N<inf>2</inf> atmosphere but the peak weight loss rates augmented evidently. In the soot pyrolysis phase, the soot content increased with the increase of particle size, and the peak weight loss rate also boosted significantly by oxidation of O<inf>2</inf>. This study aimed at assessing the oxidation features of different sizes of particles in the specified atmosphere and providing fundamental data for the after-treatment technology of diesel particulate matter.
Number of references:31
Main heading:Particles (particulate matter)
Controlled terms:Atmospheric aerosols - Atmospheric temperature - Diesel engines - Dust - Elementary particles - Gravimeters - Health hazards - Metal cladding - Oxidation - Particle size - Particle size analysis - Particulate emissions - Soot - Thermogravimetric analysis
Uncontrolled terms:After-treatment technology - Diesel particulate matters - First-order differentials - Oxidation characteristics - Particles size distribution - Thermal gravimetric analysis - Thermo-gravimetric experiments - Thermogravimetric characteristics
Classification code:951 Materials Science - 931 Classical Physics; Quantum Theory; Relativity - 802.2 Chemical Reactions - 801 Chemistry - 612.2 Diesel Engines - 538.2 Welding - 461.7 Health Care - 451.1 Air Pollution Sources - 443.1 Atmospheric Properties
DOI:10.3969/j.issn.1002-6819.2013.16.007
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679258
Title:Fatigue damage analysis and life prediction for vehicle control arm
Authors:Liu, Yongchen (1); Wang, Guolin (1); Sun, Li (2)
Author affiliation:(1) School of Automotive and Traffic Engineering, Jiangsu University, Zhenjiang 212013, China; (2) Faculty of Transportation Engineering, HuaiYin Institute of Technology, Huai'an 223003, China
Corresponding author:Wang, G.(glwang@ujs.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:83-91
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:In order to improve the vehicle structure fatigue durability, and to perfect vehicle structure design method, In this paper, fatigue damage analysis and life prediction on the vehicle control arm were done by three parts, namely, finite element modeling and analysis, load spectrum testing and establishment, fatigue damage analysis and life prediction. A fatigue life prediction method of vehicle control arm was put forward. Firstly, the finite element analysis model of the vehicle control arm was built in ANSYS software, and its construction stress was calculated and analyzed under the action of lateral and longitudinal forces respectively. Two hot points on the control arm were determined, which could bring about fatigue damage. The location of each hot point is respectively at the transition of the control arm connected to the steering knuckle and to the subframe. Both locations were identified as load testing points of P<inf>1</inf> and P<inf>2</inf> that strain gauges were pasted. Secondly, the strain load of the control arm was measured under the condition of the proving ground, nine kinds of roads were chosen in the proving ground and the vehicle speed was different on the each road. During the process of the experiment, the test was done repeatedly six times by three skilled drivers. After doing the data processing such as frequency spectrum analysis and low passing filtering, filter frequency were respectively 40 Hz and 15 Hz from the two channels of points P<inf>1</inf> and P<inf>2</inf>, and the pure signal of vehicle control arm was acquired. Then, using rain flow counting method, the load spectrum of the control arm was worked out, and load distribution histogram on the testing points were obtained, and the average value of the load was accordance with the normal distribution, the load amplitude was accordance with the Weibull distribution by using probability map method. Finally, on this basis, according to local stress-strain method and Miner standard, and stress concentration correction factor, the fatigue damage analysis and life prediction were completed for the control arm. That is, some values on the testing points of the control arm were obtained including the total damage, hour life and cycle life, etc. Structural fatigue damage distribution characteristics of the control arm were analyzed. The fatigue notch factor of the control arm two testing points were calculated respectively, and the values were 1.36 and 1.14. The main conclusions were as follows, the load signal frequency domain energy mainly concentrated within 15 Hz, which conformed to the actual frequency distribution of the vehicle body. The larger fatigue damage of the control arm were occurred mainly on vehicle sharp turns under stone road conditions, and the fatigue damage distribution of the control arm was consistent with the stress state under the actual vehicle proving ground road conditions. The final result showed that the prediction life of control arm was 39600 hours by using the ncode glyphworks 8.0 software. The paper provided an important method that combined the finite element analysis with the actual vehicle loading conditions for fatigue endurance study on the vehicle and other parts.
Number of references:24
Main heading:Finite element method
Controlled terms:Control system synthesis - Data processing - Durability - Fatigue damage - Load testing - Loads (forces) - Normal distribution - Rain - Roads and streets - Spectrum analysis - Stress concentration - Vehicles - Weibull distribution
Uncontrolled terms:Fatigue damage analysis - Fatigue life prediction - Fatigue notch factor - Finite element analysis model - Frequency distributions - Frequency spectrum analysis - Life predictions - Rain flow counting method
Classification code:922.1 Probability Theory - 921.6 Numerical Methods - 731.1 Control Systems - 723.2 Data Processing and Image Processing - 922.2 Mathematical Statistics - 483.1 Soils and Soil Mechanics - 432 Highway Transportation - 421 Strength of Building Materials; Mechanical Properties - 406.2 Roads and Streets - 443.3 Precipitation
DOI:10.3969/j.issn.1002-6819.2013.16.011
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679260
Title:Multi-objective optimization model of irrigation schedule for winter wheat-summer maize rotation system
Authors:Zhang, Zhiyu (1); Qie, Zhihong (1); Wu, Xinmiao (1)
Author affiliation:(1) College of Urban and Rural Construction, Agricultural University of Hebei, Baoding 071001, China
Corresponding author:Qie, Z.(qiezhihong@163.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:102-111
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Irrigation schedule optimization of deficit irrigation is an effective approach for water saving. Water production function models of winter wheat-summer maize were established respectively based on soil water balance model and water production function model for Wangdu irrigation station planting patterns. Jensen multiplication model for water production function models was used in this paper. Sensitive indexes of Jensen model were important parameters, which reflected the influencing extent of lacking water in all growth stages to yield and their error magnitude influences the precision of deficit irrigation schedule model. Particle swarm optimization(PSO) algorithm was used to solve sensitive indexes of this model, which can eliminate the problems of partial estimation and low fitting precision for traditional regression analysis algorithm. And a multi-objective optimization model of irrigation scheduling for winter wheat-summer maize rotation was established. In order to solve the model, a group non-dominated sorting genetic algorithm II(GNSGA-II) based on grouping sort was put forward. The real-coded including irrigation volume and time interval was adopted when designing genetic encoding, so we can get the exact irrigation dates and irrigation volume. Finally, the exact irrigation volume and irrigation dates were obtained under different available irrigation volume. The results showed that the irrigation dates distribute all growth stages except over-wintering for winter wheat because of the minimum sensitive index. The distinction of irrigation date is no more than two days under different available irrigation volume, that is to say irrigating in the two days is appropriate comparatively no matter what the available irrigation water volume is. The irrigation volume and yield of winter wheat and summer maize increase along with the increase of total water volume, but show different trends for the two crops due to different sensitive indexes. Due to set the two objects which are maximal total output value and minimal irrigation water volume and genetic algorithm considered the two objects at the same time in the course of optimization, so there is no appearance that the actual irrigation volume equal to available irrigation volume in the Pareto non-inferior solution set. The total actual irrigation volume is 472mm (the irrigation volume of winter wheat is 225 mm while the summer maize is 247 mm) when the available irrigation volume less than 500mm in a year. The difference of actual irrigation volume and available irrigation volume is 28mm because the relative yield for the two crops are 0.975 and 0.978 when the total irrigation volume reach 472mm which means the two crops approach abundant irrigation. The marginal profit of irrigation will gradually decrease with the total water volume increase. The limited water resources can be reasonable allocated and used based on optimization results in a year in order to gain the higher total output value.
Number of references:26
Main heading:Irrigation
Controlled terms:Crops - Genetic algorithms - Mathematical models - Multiobjective optimization - Particle swarm optimization (PSO) - Regression analysis - Water conservation - Water management - Water supply
Uncontrolled terms:Irrigation schedule - Irrigation scheduling - Multi-objective optimization models - Non-dominated sorting genetic algorithm-II - Particle swarm optimization algorithm - Soil water balance - Soil water balance model - Water production functions
Classification code:921.5 Optimization Techniques - 921 Mathematics - 821.4 Agricultural Products - 922.2 Mathematical Statistics - 821.3 Agricultural Methods - 446 Waterworks - 444 Water Resources - 446.1 Water Supply Systems
DOI:10.3969/j.issn.1002-6819.2013.16.013
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679270
Title:Linear optimal operation model and algorithm for active distribution network in rural areas
Authors:Niu, Huanna (1); Yang, Minghao (1); Jing, Tianjun (1); Li, Hancheng (2); Lu, Jiyuan (1)
Author affiliation:(1) College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China; (2) Beijing Electric Power Company, Beijing 100031, China
Corresponding author:Jing, T.(jtjy11@cau.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:190-197
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:The active energy exchange in distribution networks of rural areas is becoming more significant with the development and access of DGs and Microgrids. Therefore, the optimization scheduling technology for active distribution networks, in which the DGs as a controllable scheduling unit involved in the distribution network OPF operation scheduling to achieve global optimization of energy management, will be the focus of research in the future rural smart distribution grid. The standing point of active energy optimization scheduling for rural distribution network with DGs, based on the research of real-time optimization scheduling for active distribution network which is achieving three objectives of the network loss as small as possible, the node voltage offset as small as possible and the cost of purchasing power as small as possible, focused on the problem of network loss and node voltage offset with DG's output showing a non-linear relationship which makes the scheduling problem becomes a nonlinear multi-objective optimization problem, based on the simulation analysis that distributed generations affect voltage distribution and line losses of distribution network, a linear model and solution methods for active distribution network real-time optimization scheduling is proposed in this paper. The simulation of generations output to voltage distribution and network loss shows that the optimal schedule scheme can be searched in two directions of reducing the voltage deviation and improving the grid voltage level. This obeys a physical principle, that is, the voltage distribution in the network is smooth, the voltage drop will be small, and the current through the line will be very small for constant line impedance. In addition, higher voltage levels lead to lower currents and net losses when transferring the same power. Thus, in this paper, the two optimization directions are achieved by shortening the range of node voltage limits and calculating the highest voltage level of the network at the same voltage deviation. Based on the above research, a optimization model was established in which maximum node voltage to the whole network was the objective, the simplified loop voltage equation was power flow balance constraint, voltage offset limits satisfying iteration reduction and DGs' output limits are the inequality constraints. Subsequently, it makes use of the features that each node voltage phase angle having little difference in distribution networks to transform the loop voltage equation directly into linear function of the DGs' output, thus the optimization-scheduling model for active distribution network was transformed into a linear programming model. Finally, according to a shrinking node voltage deviation limit value and calculating the highest voltage level of the network at the same voltage deviation, the optimal control scheme was obtained, which can also meet the two objectives of minimum voltage deviation and minimum loss. The model and algorithm are validated in an IEEE33 example, and it was proved when the DGs' output was optimized via the proposed method, the voltage distribution became even smoother, the voltage level was near normal, and the network loss became even smaller. Compared to the conventional non-linear optimization model for the distribution operation, the linear model presented in this paper can not only improve the calculation speed but also is guaranteed to obtain an optimal solution in mathematical theory.
Number of references:31
Main heading:Mathematical models
Controlled terms:Algorithms - Computer simulation - Constraint theory - Distributed power generation - Global optimization - Iterative methods - Linear programming - Mathematical transformations - Models - Optimization - Research - Rural areas - Scheduling - Voltage control - Voltage distribution measurement
Uncontrolled terms:Active distribution networks - Linear optimization - Linear programming models - Multi-objective optimization problem - Non-linear relationships - Optimization scheduling - Rural distribution networks - Smart distribution grids
Classification code:961 Systems Science - 942.2 Electric Variables Measurements - 921 Mathematics - 912.2 Management - 902.1 Engineering Graphics - 901.3 Engineering Research - 821 Agricultural Equipment and Methods; Vegetation and Pest Control - 731.3 Specific Variables Control - 723.5 Computer Applications - 702 Electric Batteries and Fuel Cells - 615 Thermoelectric, Magnetohydrodynamic and Other Power Generators
DOI:10.3969/j.issn.1002-6819.2013.16.024
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679282
Title:Predictive model on tenderness of postmortem yak meat and its validation
Authors:Zhang, Li (1); Sun, Baozhong (2); Yu, Qunli (1)
Author affiliation:(1) College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, 730070, China; (2) Institute of Animal Science, Chinese Academy of Agricultural Science, Beijing 100193, China
Corresponding author:Zhang, L.(zhanglwubd@163.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:286-292
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Tenderness is one of important sensorial properties for the quantitative evaluation of eating qualities influencing the consumption of beef, and the others are juiciness and flavor respectively. Poor tenderness is one of main causes for commercial unacceptability of yak meat. The variation of physiological and biochemical characteristics during tenderization at the initial phase of postmortem aging has an extraordinarily significant effect on the postmortem formation of the tenderness property of beef cuts, which is one of determinant factors for consumers to decide if the beef products should be purchased. Therefore, the improvement of research on the effect of physiological and biochemical characteristics on the tenderness of yak meat is beneficial to melioration of the theory of postmortem aging and tenderization of yak meat. In order to investigate the effect of the postmortem variation of physiological and biochemical characteristics on the formation of tenderness of yak meat, pH, glycogen content, calpain activity (CA), the myofibrillar fragmentation index (MFI), sarcomere length, myofiber diameter, and shearing force of M. longissimus dorsi stored at 4°C for 10d from 18 male yaks were determined. The estimated value of 6 characteristics at postmortem 1 h were obtained directly as alternative predictors of a predictive model of postmortem tenderness of yak meat. Meanwhile, the kinetic parameters of the rate and extent of variation of some physiological and biochemical characteristics including pH, CA, MFI and glycogen content obtained by kinetic data analysis within postmortem 72 h were also selected as alternative predictors. The ultimate predictors of a predictive model of postmortem tenderness of yak meat were determined through a "jackknife" method from all alternative predictors, including 6 variables at postmortem 1 h and 7 kinetic parameters within postmortem 72 h according to occurrences in optimal equations of 15 jackknife samples through multiple linear step regression analysis. The ultimate predictors included rate of CA decline (R<inf>CA</inf>), extent of pH decline (E<inf>pH</inf>), rate of pH decline (R<inf>pH</inf>), and rate of glucogen decline (R<inf>Glu</inf>). The predictive model of tenderness was also built within a randomly selected 15 male yaks different from the jackknife samples through multiple linear enter regression analysis, to shearing force at postmortem 6 d (T<inf>6</inf>) as the dependent variables, to the above four predictors as independent variables. The predictive equation is T<inf>6</inf> = 50.414 10.924E<inf>pH</inf> 53.029R<inf>pH</inf>-519.690R<inf>CA</inf> 65.757R<inf>Glu</inf>, with determinate coefficient R2 of 0.703, which could explain 70.3% of the variability of the shearing force of yak meat at postmortem 6d. The data of the other 3 male yaks was used as a validation set. The determinate coefficient R2 between the predictive value obtained by model and reference value of the validation set was 0.977. The relative errors between predictive value and reference value of the validation set were not higher than 5%. Therefore, the tenderness of yak meat at postmortem 6d could be effectively predicted through this predictive model, based on the variation of physiological and biochemical characteristics within postmortem 72h.
Number of references:26
Main heading:Physiological models
Controlled terms:Aging of materials - Biochemistry - Kinetic parameters - Meats - Physiology - Quality control - Regression analysis - Shearing
Uncontrolled terms:Fragmentation index - Independent variables - Physiological and biochemical characteristics - Predictive equations - Predictive modeling - Quantitative evaluation - Sensorial properties - Tenderness
Classification code:931 Classical Physics; Quantum Theory; Relativity - 922.2 Mathematical Statistics - 913.3 Quality Assurance and Control - 822.3 Food Products - 951 Materials Science - 801.2 Biochemistry - 461.9 Biology - 461.1 Biomedical Engineering - 421 Strength of Building Materials; Mechanical Properties - 604.1 Metal Cutting
DOI:10.3969/j.issn.1002-6819.2013.16.036
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679274
Title:Modeling spatial determinants of land urbanization in urban fringe
Authors:Wu, Wei (1); Zhou, Shenglu (1); Wei, Yehua (2); Chang, Ting (1)
Author affiliation:(1) School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210093, China; (2) Department of Geography, University of Utah, Salt Lake City 84112, United States
Corresponding author:Zhou, S.(zhousl@nju.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:220-228
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Urban expansion can be seen as a spatial non-stationary process because of the natural environment, social and economic characteristics are distinctive in different regions. The complexity of land use in urban fringe determines its unique urbanization process and mechanism, to explore the driving factors of land use change in urban fringe is not only helpful to the alleviation of land use conflicts and the optimization of urban space structure but also has a realistic significance in the protection of cultivated land resource and ecological environment. Based on remote sensing images in 1999 and 2010 and GIS data, we spatially integrated proximity variables, neighborhood variables and policy variables with global logistic regression model and local geographically weighted logistic regression (GWLR) model to explore driving factors of urban expansion in the urban fringe area with Jiangning District of Nanjing as an example. Results showed that: 1) logistic model and GWLR model respectively explained 51%, 64% of urban land change of the study area over historical periods, and the latter model had advantages in local estimation with better parameters which could be better applied to simulation, prediction and mechanism investigation of urban expansion in the study area. Moreover, land use data sampling integrated system sampling and random sampling, which could effectively reduce the influence of spatial autocorrelation on the research results. 2) Considering the two model results, X<inf>3</inf>, X<inf>5</inf>, X<inf>1</inf> which belong to proximity variables; X<inf>6</inf> which belongs to neighborhood variables and X<inf>11</inf> which belongs to policy variables were the key explanatory variables for urban expansion in the studied area. It indicated the agglomeration effects of industrial park and urban center in urban fringe area, as well as promotion role of the land market and internal transportation network, were important driving factors to the urban land change of urban fringe. 3) Using GIS tools, GWLR model could visualize the spatial non-stationary characteristics of driving factors, in order to explore a more intuitive and profound drive mode of urban expansion in the study area. Different explanatory varieties presented individual spatial pattern, according to which we discovered the main driving factors and limited factors of urban expansion in different districts of the study area. This could provide a new perspective for farmland and ecology protection. Overall, the government's leading power represented by land transferring behavior and development zone construction were the core motivation for urban expansion in the studies area, which reflected the common characteristics of urban suburbanization of China to some extent and provided some advices for the land management in the similar urban fringe.
Number of references:26
Main heading:Computer simulation
Controlled terms:Digital storage - Ecology - Expansion - Geographic information systems - Image reconstruction - Land use - Mathematical models - Models - Regression analysis
Uncontrolled terms:Economic characteristics - Internal transportation - Logistic models - Logistic Regression modeling - Non-stationary characteristics - Spatial autocorrelations - Urban fringe - Urbanization
Classification code:922.2 Mathematical Statistics - 921 Mathematics - 902.1 Engineering Graphics - 741 Light, Optics and Optical Devices - 951 Materials Science - 723.5 Computer Applications - 722.1 Data Storage, Equipment and Techniques - 454.3 Ecology and Ecosystems - 403 Urban and Regional Planning and Development - 723.3 Database Systems
DOI:10.3969/j.issn.1002-6819.2013.16.028
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679280
Title:Combination of modified atmosphere packaging and 1-methylcyclopropene treatment suppress decreasing of wax composition of apples during cold storage
Authors:Dong, Xiaoqing (1); Rao, Jingping (1); Zhu, Shouliang (1); Yang, Qingzhen (1)
Author affiliation:(1) College of Horticulture, Northwest A and F University, Yangling 712100, China
Corresponding author:Rao, J.(dqr0723@163.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:269-277
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Modified atmosphere packaging (MAP) is a very useful method in postharvest storage for fruits and vegetables by altering the gaseous environment of the stored commodities. 1-methylcyclopropene (1-MCP) is a potent inhibitor of ethylene action, and has been extensively researched in a variety of horticultural crops, especially climacteric fruits. Greasiness is a problem for apples following their prolonged storage. At present, the storage quality and physiology property of fruits and vegetables treated with MAP or a combination of MAP and 1-MCP have been studied, however, there are few reports about the effects of MAP or a combination of MAP and 1-MCP on the wax composition of an apple during storage. The objective of this study was to study the changes of primary wax composition during storage and the relationship of wax composition and greasiness and the quality of apple fruit during storage after treatment with MAP and MAP 1-MCP. The effects of MAP of 0.03 mm polyvinyl chloride bags and a combination of MAP and 1 μL/L 1-MCP were investigated on total wax and primary wax components. Included were nonacosane and heptacosane which were saturated hydrocarbons representing the predominant component (95%) of nonpolar wax components, hexadecanoic acid, the most abundant saturated fatty acid, and 9, 12-octadecadienoic acid, the most abundant polyunsaturated fatty acid of polar wax components, and nonacosan-10-ol (secondary alcohol) and nonacosan-10-one (ketone), the latter two of which have a relationship with fruit greasiness. Wax composition of "Red Fuji" apples (Malus domestica Borkh. 'Red Fuji') was investigated by gas chromatography-mass spectrometry. Analyses of fruit quality during storage at (0±1)°C for seven months included firmness, soluble solid content (SSC), titratable acid (TA), SSC/TA ratio, respiration rate, ethylene release, and weight loss. Wax was extracted using chloroform/methanol (3:1, v/v), and eluted stepwise with n-hexane (heptadecane as an internal standard) for nonacosane and heptacosane and methanol (deuterated heptadecanoic acid as internal standard) for hexadecanoic acid, 9, 12-octadecadienoic acid, nonacosan-10-ol, and nonacosan-10-one. The results indicated that total wax of the control fruit declined during storage and fruit treated with MAP and MAP 1-MCP increased during the first month and then declined over first to seven months, In all treatments, nonacosane and heptacosane declined, while hexadecanoic acid and 9, 12-octadecadienoic acid increased. Nonacosan-10-ol and nonacosan-10-one declined, followed by an increase over seven months storage at (0±1)°C. Nonacosan-10-ol and nonacosan-10-one of the control fruit and MAP-treated fruit declined during the first three months and then increased, but fruit treated with MAP 1-MCP declined during the five months and then increased. Changes in total wax and primary wax components were delayed or suppressed in fruit subject to MAP and MAP 1-MCP treatments, especially for MAP 1-MCP-treated fruit. Compared with the control, MAP and MAP 1-MCP delayed the decline in flesh firmness, TA and SSC and reduced ethylene and respiration rates and weight loss. MAP and MAP 1-MCP treatments suppressed development of apple greasiness, presumably due to altered wax composition, but did not alter fruit flavor. MAP 1-MCP was more effective than MAP for suppressing changes in wax composition and maintaining storage quality. The results of this study indicate that a combination MAP/1-MCP treatment was the most effective for maintaining the quality of "Red Fuji" apple fruit during long-term storage.
Number of references:34
Main heading:Fruits
Controlled terms:Cold storage - Energy storage - Ethylene - Gas chromatography - Hexane - Ketones - Linoleic acid - Modified atmosphere packaging - Packaging - Palmitic acid - Physiology - Plants (botany) - Polyunsaturated fatty acids - Saturated fatty acids - Vegetables
Uncontrolled terms:1-MCP - 1-methylcyclopropene (1-MCP) - Apple - Fruits and vegetables - Gas chromatography-mass spectrometry - Malus domestica Borkh - Saturated hydrocarbons - Soluble solid content
Classification code:821.4 Agricultural Products - 804.1 Organic Compounds - 801 Chemistry - 702 Electric Batteries and Fuel Cells - 694.4 Storage - 694.1 Packaging, General - 461.9 Biology
DOI:10.3969/j.issn.1002-6819.2013.16.034
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679268
Title:Resource-saving audio signal acquisition methods based on compressed sensing theory
Authors:Guo, Xiaohua (1); Chen, Wenyue (2)
Author affiliation:(1) Fair Friend Institute of Electromechanics, Hangzhou Vocational and Technical College, Hangzhou 310018, China; (2) Hangzhou Academy of Agricultural Sciences, Hangzhou 310024, China
Corresponding author:Guo, X.(guoxiaohua77@sina.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:174-181
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:In order to reduce the cost by multimedia signal sampling, processing, transmission of computing, storage, electricity, bandwidth resources in an environment-monitoring system built on a wireless sensor networks, this paper analyzed the limitations of the existing signal processing theory and random sampling methods. An improved additive random sampling method and the sampling time sequence obtained by this method had the same probability density function with the existing random sampling method. The proposed method effectively avoiding the phenomenon of adjacent sampling time interval was too large or too small, and each sequential sampling time had a clear causal relationship. On this basis, a novel resource-saving audio signal acquisition method was designed. In the proposed signal acquisition method, the audio signal acquisition was completed by cooperation between the sensor nodes and the sink nodes. The sensor nodes took the low frequency random sampling with the sparse audio signal, and the sink nodes reconstructed the original signal with high probability by using the received random sampling data. Then a test system was established with 13 acquisition nodes and a sink node based on the Zigbee network technology, and this system was used to implement the remote, wireless, and distributed acquisition of the crawl acoustic signal of Tribolium castaneum Herbst adults in grain barrel. In the test system, the proposed signal acquisition method was compared with the existing data compression method. Results showed that if the maximum data reconstruction error was less than 0.5%, the packet loss rate was less than 10% and each acquisition node only sampled one acoustic signal, then the packet loss rate was 9.1%and the maximum reconstruction error was 0.44% by using the proposed signal acquisition method. However, if using the existing data compression method, packet loss rate and the maximum reconstruction error were 9.3% and 0.46% respectively. Two acquisition methods had similar performance, and could achieve the remote, wireless, real-time acquisition for 13 acoustic signals. For the proposed audio signal acquisition method, when the sampling frequency was as low as 196 Hz, the packet loss rate and the maximum reconstruction error were 21.6% and 0.48%, respectively. But for the proposed signal acquisition method, the sampling frequency was only 586Hz, and it effectively reduced the resource consumption of acoustic signal acquisition. The method proposed in this paper can provide references especially for the wireless sensor networks with limited resources.
Number of references:21
Main heading:Sensor nodes
Controlled terms:Acoustic waves - Compressed sensing - Data compression - Digital storage - Probability density function - Sensors - Signal analysis - Signal processing - Signal reconstruction - Signal sampling - Wi-Fi - Zigbee
Uncontrolled terms:Audio - Causal relationships - Random sampling method - Real time acquisition - Reconstruction error - Resource consumption - Sampling frequencies - Signal processing theory
Classification code:922 Statistical Methods - 921 Mathematics - 801 Chemistry - 751.1 Acoustic Waves - 723 Computer Software, Data Handling and Applications - 722 Computer Systems and Equipment - 716.1 Information Theory and Signal Processing
DOI:10.3969/j.issn.1002-6819.2013.16.022
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679248
Title:Advances in research of controlled drainage for crop production and environmental protection
Authors:Luo, Wan (1); Li, Shan (1); Jia, Zhonghua (1); Liu, Wenlong (1); Pan, Yanxin (1); Wu, Di (1)
Author affiliation:(1) Northwest Key Laboratory of Water Resources and Environment Ecology, Xi'an University of Technology, Xi'an 710048, China
Corresponding author:Luo, W.(wluo@mail.xaut.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:1-6
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Controlled drainage, also known as water table management, is an environmental friendly agricultural water management practice. It has been widely advocated in recent years to reduce drainage discharge in order to reduce agricultural non-point source pollution while ensuring crop production. Further research and application of the controlled drainage are of great importance to drainage system design and water management in a changing environment. In this paper, we reviewed the development history, multiple functions and research advances of the controlled drainage in China and the world. The development of controlled drainage technique has experienced several stages, advancing from its original purpose of water conservation to later goals of nutrient loss reduction, and irrigation water saving etc. Implementation of controlled drainage can be performed easily with water level control structures installed at the outlet of drainage ditch or pipe. However, properly schedule water level adjustment at the outlet remains a challenge, considering the variable weather conditions and different crop drainage requirements. In saline agricultural environment, controlled drainage has to meet the requirement of salinity control. Existing research has demonstrated that controlled drainage can achieve multiple benefits in reducing nutrient losses and conserving water in humid regions, and controlling soil salinity and saving irrigation water in arid and semi-arid regions. Controlled drainage in coastal regions has additional benefits of reducing rain water losses and lowering the risk of salt water intrusion. While controlled drainage research in China is relatively lagged behind, this water table management technique has long been used by grass root farmers to reduce drainage intensity for less irrigation requirement. For many areas in China, where rice and dry foot crop are rotationally cultured, controlled drainage has the advantages of adjusting drainage intensity flexibly to meet moisture level requirement of different crops. The present need in controlled drainage is to make appropriate water level control schedules that are easy to implement and consistent with local crop production requirement. Computer modeling has been widely used to examine long term effect of controlled drainage on hydrology and nitrogen losses. DRAINMOD model is the mostly used simulation tool that predicts outcome of different drainage system layout under variable weather, soil and cropping conditions; the nitrogen module-DRAINMOD_NII enables the model to predict nitrogen losses from drained agricultural fields under different water management, tillage and fertilization practices. Lacking of field observations is the major obstacle in applying modeling approach for controlled drainage research in China. In summary, we conclude that controlled drainage is a necessary practice for modern agricultural drainage; providing benefits in regulating soil moisture in the drained fields, reducing nutrient losses, saving irrigation water use and increasing rainwater use, controlled drainage is the best practice for drainage water management for sustainable agricultural development.
Number of references:38
Main heading:Environmental management
Controlled terms:Arid regions - Crops - Cultivation - Drainage - Groundwater - Irrigation - Level control - Nitrogen - Nutrients - Research - Soil conservation - Soil moisture - Water conservation - Water levels - Water management - Water quality - Water supply
Uncontrolled terms:Agricultural environments - Agricultural non-point source pollutions - Agricultural water management - Arid and semi-arid regions - Salinity - Sustainable agricultural development - Water - savings - Water table management
Classification code:483.1 Soils and Soil Mechanics - 502 Mines and Quarry Equipment and Operations - 614.2 Steam Power Plant Equipment and Operation - 454.1 Environmental Engineering, General - 731.3 Specific Variables Control - 821 Agricultural Equipment and Methods; Vegetation and Pest Control - 901.3 Engineering Research - 804 Chemical Products Generally - 453.2 Water Pollution Control - 406 Highway Engineering - 442 Flood Control; Land Reclamation - 443 Meteorology - 401 Bridges and Tunnels - 444 Water Resources - 446 Waterworks - 446.1 Water Supply Systems - 444.2 Groundwater
DOI:10.3969/j.issn.1002-6819.2013.16.001
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679261
Title:Topology optimization method for zoning of high concrete face rockfill dam
Authors:Gao, Zhaoliang (1); Wang, Zhengzhong (2); Shi, Jiao (2); Cai, Kun (2)
Author affiliation:(1) Institute of Soil and Water Conservation, Northwest A and F University, Yangling 712100, China; (2) College of Water Resources and Architectural Engineering, Northwest A and F University, Yangling 712100, China
Corresponding author:Cai, K.(kuicansj@163.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:112-118
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Concrete face rockfill dam (CFRD) is very popular in modern dam engineering applications due to its low cost, stability, adaptability and environment friendly. In CFRD engineering, many accidents are caused by the cracks of face plates. Especially, most of high CFRDs (over 100 m) have cracks in their face plates that reduce the safety of dams in operation. One of the main reasons for the cracks in face plates of a high CFRD is difference between the deformation of the face plates and dam body under gravity and upstream water pressure. Clearly, the deformation of dam body is determined by not only gravity and the water pressure, but also the distribution of filled materials. Therefore, the layout of the materials in dam body is essential to CFRD engineering. Taking TSQ-1 CFRD as an example, the best partition form of dam material within cross-section of a high CFRD was analyzed by continuum topology optimization. In traditional design, the zoning of material was given mostly according to designer's experiences and however, the intuitive method is not feasible because the height of CFRD is over 200 m. In this research, a continuum topology optimization method was proposed to find the optimal partition of the filled materials in CFRD. Considering the differences among the elasticity of materials in dam body, a material set was formed with the materials in respect to their tangential moduli. The deformation of structure was solved using finite element (FE) method and the material number of each FE was chosen within the material set. The purpose of the present research was to find the optimal material numbers in finite elements in design domain. A heuristic method was presented and similar to evolutionary structural optimization (ESO) as considering the update rule of material properties in optimization process. Here, a criterion was adopted to renew the design variables, i.e., the material numbers with respect to the tangential modulus of materials in dam body. To keep the stability of algorithm, no more than 5% of total elements' material number will be renewed in iteration. The results indicated that there were obvious differences between the layout of optimized material and that of the traditional partition. High modulus materials were located in the lower side of the upper reaches and various materials changed gradually with respect to the moduli from the upstream to downstream. And boundary slope ratios of materials were not lower than 1:0.8. Compared with the original design, deformation of panel in optimized dam was slighter and more uniform under water pressure, which helps to prevent face plate from breaking.
Number of references:21
Main heading:Design
Controlled terms:Computer aided engineering - Concretes - Cracks - Dams - Deformation - Elasticity - Finite element method - Fracture - Gravitation - Heuristic methods - Iterative methods - Materials - Optimization - Plates (structural components) - Rivers - Rock mechanics - Topology - Zoning
Uncontrolled terms:Concrete face rockfill dam - Continuum topology optimization - Dam materials - Environment friendly - Evolutionary structural optimization - Optimal partitions - Rock-fill dam - Topology Optimization Method
Classification code:931.5 Gravitation, Relativity and String Theory - 931.1 Mechanics - 921 Mathematics - 723.5 Computer Applications - 441.1 Dams - 951 Materials Science - 421 Strength of Building Materials; Mechanical Properties - 408.2 Structural Members and Shapes - 408 Structural Design - 407.2 Waterways - 403.2 Regional Planning and Development - 412 Concrete
DOI:10.3969/j.issn.1002-6819.2013.16.014
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679257
Title:Analysis on vibration characteristics of S-shaped shaft-extension tubular pumping system
Authors:Yang, Fan (1); Liu, Chao (1); Tang, Fangping (1); Zhou, Jiren (1)
Author affiliation:(1) College of Water Resource and Energy Power Engineering, Yangzhou University, Yangzhou 225009, China; (2) Hydrodynamic Engineering Laboratory of Jiangsu Province, Yangzhou 225000, China
Corresponding author:Yang, F.(sqyzyangfan@126.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:74-82
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:A physical model test was adopted to study the energy performance of an S-shaped shaft-extension tubular pumping system at 5 blade angles (θ=-4°, -2°, 0°, 2°, 4°) by energy tests in the hydrodynamic engineering laboratory of Jiangsu Province, of which total uncertainty is ±0.39%. A signal collecting analyzer EN900 and a vibration velocity transducer VS-080 made by Schenck Process GmbH were used to study the vibration characteristics of model pumping system at blade angle 4° and -4° based on different pumping system operating conditions with the pumping system head range from 0.0 m to 7.0 m at the same rotating speed. Two measuring points P1 and P2 were arranged in the inlet of the guide vane. The X direction indicates the radial direction measured by P1; the Y direction indicates the vertical direction which measured by P2. The test results show that the highest hydraulic efficiency of the pumping system is 83.55% at blade angle -2°, the flow rate is 289.58 L/s and the pumping system head is 4.438 m. Compared with the hydraulic efficiency of traditional shaft tubular pumping system, that of the new S-shaped shaft-extension tubular improves by about 5%. Compared with the highest hydraulic efficiency of hydraulic model TJ04-ZL-23 in the range of blade angle -4°- 4°, the maximum decrease in the maximum efficiency is 5.22% at a blade angle of 4°, and the minimum decrease is 2.47% at a blade angle of 2°. At the same blade angle, the amplitude A<inf>p-p</inf> of the X direction is higher than that of the Y direction, but the dominant frequency of both has the same value in any operating conditions. With increasing pumping system head, the amplitude A<inf>p-p</inf> of the X direction decreases first then increases. At the same value of pumping system head, the amplitude A<inf>p-p</inf> of the X direction at a positive blade angle is higher than that at a negative blade angle. There is little difference between the amplitude A<inf>p-p</inf> of the Y direction at different blade angles. The maximum amplitude A<inf>p-p</inf> of the X direction is 74.526 μm and that of Y direction is 27.679 μm in different testing conditions, both of which are less than the maximum allowable value (or, alternatively, "tolerance"). The dominant vibration frequency is 22.5Hz for monitoring points P1 and P2 at blade angle 4°, which is the same as rotation frequency, while the dominant vibration frequency is 45 Hz for monitoring points P1 and P2, which is different from both the rotation frequency and the blade frequency. The rotation frequency is the main influence on the frequency of the pumping system vibration at blade angle 4°. An expression was established for the functional relation between the unbalanced vibration frequency and the rotation frequency and blade number. The dominant frequency of unbalanced vibration at monitoring points P1 and P2 is equal to the product of one third of the blade number and the rotating frequency at blade angle 4°, while at blade angle -4° the dominant frequency of unbalanced vibration at monitoring points P1 and P2 is equal to the product of two thirds of the blade number and the rotating frequency. The dominant vibration frequency is therefore a different function of rotation frequency and blade frequency for different blade angles. The study can be a reference for type selection and design of a pumping system.
Number of references:23
Main heading:Turbomachine blades
Controlled terms:Efficiency - Hydraulic machinery - Hydraulic models - Industrial plants - Laboratories - Pumping plants - Pumps - Rotation - Vibration analysis - Well pumps
Uncontrolled terms:Engineering laboratories - Hydraulic efficiency - Model tests - Operating condition - Rotating frequencies - Rotation frequencies - Vibration characteristics - Vibrations
Classification code:913.1 Production Engineering - 801 Chemistry - 632.2 Hydraulic Equipment and Machinery - 632.1 Hydraulics - 943.2 Mechanical Variables Measurements - 618.2 Pumps - 601.1 Mechanical Devices - 446 Waterworks - 402.1 Industrial and Agricultural Buildings - 618 Compressors and Pumps
DOI:10.3969/j.issn.1002-6819.2013.16.010
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679252
Title:Dynamics modeling and experiments of 3-DOF parallel mechanism with actuation redundancy
Authors:Niu, Xuemei (1); Gao, Guoqin (1); Liu, Xinjun (2); Bao, Zhida (1)
Author affiliation:(1) School of Electrical and Information Engineering, Jiangsu University, Zhenjiang 212013, China; (2) Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
Corresponding author:Niu, X.(niuxm@mail.ujs.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:31-41
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Dynamics modeling plays an important role in the application of agricultural robots, which is the key to analyze the dynamic characteristics and achieve high-precision operation. This paper addressed the issue of deriving the dynamic formulation of a novel 3-DOF redundantly actuated parallel mechanism. The structure of the parallel mechanism is composed of a moving platform attached to a fixed platform through two identical PRRR kinematic chains and one PPRR chain. The parallel mechanism has two translational degrees and one rotational degree. Firstly, inverse kinematic solution of the parallel mechanism was studied by analyzing the structure property and the constraint equation; Secondly, according to the kinematics of the redundant mechanism and considering fully the impact of inertial force for each component, the inverse dynamic equation was formulated in the task space by using the Lagrangian formalism, and the driving force was optimized by utilizing the minimal 2-norm method. By investigating the contribution of each term in the dynamic model to the driving force, a simplified strategy of the dynamic model for real-time control application was proposed. Simulation and experimental results showed that the maximal value of the driving force for the parallel mechanism without actuation redundancy was 15N, but that of mechanism with actuation redundancy was 10N and the driving force peak was reduced by 33%. It is noted that the point β=57.6460° was the singularity which should be avoided in practical application. Additionally, the maximal tracking errors for the end-effector were 0.8mm, 0.6mm and 0.068° in Y, Z and β direction, respectively. Thus the parallel mechanism system based on the proposed dynamic model can achieve good tracking performance. This research provides technology reference for further study of high precision real-time control of parallel mechanism.
Number of references:29
Main heading:Dynamics
Controlled terms:Dynamic models - Kinematics - Mechanisms - Real time control - Redundancy - Robots
Uncontrolled terms:Dynamic characteristics - High-precision operation - Inverse dynamic equations - Inverse kinematic solutions - Parallel - Redundant actuation - Redundantly actuated - Simplified strategies
Classification code:931.1 Mechanics - 921 Mathematics - 914 Safety Engineering - 903 Information Science - 732 Control Devices - 731 Automatic Control Principles and Applications - 601.3 Mechanisms
DOI:10.3969/j.issn.1002-6819.2013.16.005
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679262
Title:Statistical characteristics of random distribution of shrinkage cracks on farmland soil surface
Authors:Zhang, Zhanyu (1); Zhu, Wenyuan (1); Zhu, Chengli (1); Wang, Ce (1); Wu, Chunhui (1); Si, Han (1)
Author affiliation:(1) College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
Corresponding author:Zhang, Z.(zhanyuzh@126.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:119-124
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Agricultural soil cracks generated during drying process becomes one of the causes of preferential flow. Generalizing crack network structure reasonably is an important research in the field. A laboratory experiment was carried out to investigate the law behind the development of shrinkage cracks on the soil surface under different types of cultivated land. In this investigation, computer image processing technique was applied to quantificationally analyze the statistical law of crack morphology and a dynamic description method based on normal distribution was proposed to depict the morphology of shrinkage cracks on soil surface. It showed that crack area density and length density both increased with decreasing moisture content and remained stable after reaching their maximums. Crack area density of paddy field (PF) specimen was a little bit bigger than that of upland field (UF) specimen throughout the drying process while the crack length density of both specimens didn't appear to be much different under the same mass moisture content. The connectivity index increased with decreasing moisture content and finally tended to be stable. The maximum connectivity index of PF specimen was 0.935 around a mass moisture content of 20% while for the UF specimen was 0.598 around a mass moisture content of 12%, reflecting that cracks of PF specimen were more closely connective to each other and the crack network of PF specimen formed faster. The connectivity index is applicable to account for the forming process and actual connectivity of shrinkage crack network under different types of cultivated land. Results suggested that crack area probability density and cumulative probability were in line with normal distribution. Both mean value and standard deviation had fairly good correlation with moisture content. Their coefficients of determination of UF specimen were larger than 0.99 and 0.98, respectively. The crack area coefficient of determination of different farmland types between the measured values and theoretical values of probability density function were both larger than 0.94, while for the crack length were both larger than 0.91, and their root mean square error(RMSE) were both less 0.20. The crack area coefficient of determination of different farmland types between the measured values and theoretical values of the distribution function were both larger than 0.90, while for the crack length were both larger than 0.94. And their RMSE were both less than 0.12. This research indicated that normal distribution is appropriate to depict crack morphology on soil surface through, which is feasible to study the formation mechanism of soil crack and the effect of different crack shapes on soil preferential flow.
Number of references:19
Main heading:Cracks
Controlled terms:Farms - Groundwater flow - Image processing - Land use - Mean square error - Moisture determination - Morphology - Normal distribution - Probability density function - Shrinkage - Soils - Statistical methods
Uncontrolled terms:Coefficient of determination - Computer image processing - Connectivity indices - Cultivated lands - Cumulative probabilities - Random distribution - Root mean square errors - Statistical characteristics
Classification code:944.2 Moisture Measurements - 922.2 Mathematical Statistics - 922.1 Probability Theory - 821 Agricultural Equipment and Methods; Vegetation and Pest Control - 951 Materials Science - 741 Light, Optics and Optical Devices - 444.2 Groundwater - 421 Strength of Building Materials; Mechanical Properties - 403 Urban and Regional Planning and Development - 483.1 Soils and Soil Mechanics
DOI:10.3969/j.issn.1002-6819.2013.16.015
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679264
Title:Automatic measuring and controlling system of weighing lysimeter based on LabVIEW and ARM processors
Authors:Guo, Huijun (1); Zhang, Jianfeng (2); Wang, Zhilin (2); Geng, Xiaojiang (2)
Author affiliation:(1) College of Automation and Information Engineering, Xi'an University of Technology, Xi'an 710048, China; (2) Institute of Water Resources, Xi'an University of Technology, Xi'an 710048, China
Corresponding author:Zhang, J.(jfzhang@mail.xaut.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:134-141
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:With the great developments of agricultural productions and concerned research projects needs in China, the use of direct methods using lysimeters for measuring water and solute flow in soils has increased in recent years. Large weighable lysimeters were best suitable for obtaining reliable data about seepage water quantity and quality. The field lysimeters combined the advantages of true field conditions and laboratory possibilities of varying parameters, handling and maintenance. Instrumentation varied due to the specific needs of each application. In order to provide a unified software and hardware platforms and system configuration scheme for the automatic measuring and controlling lysimeters, a new method using the LabVIEW and ARM processors was proposed in this paper. The systems proposed consisted of three sections: the tank holding the main soil body, the weighing and load control system, the supervisory control and data acquisition system. The weighing and load control system, which were the core parts in the lysimeter, consisted of a precise electric balance with high resolution, multi-stage lever systems and an intelligent load control system. The balance, with resolution up to 0.1 g, connected with the host computer by RS232 bi-directional interface. To improve the reliability and accuracy of weighing system further, an intelligent load control system was developed based on the LPC1768 MCU, which communicated with the host computer via the RS485 interface. The supervisory control and data acquisition system mainly consisted of the data acquisition units, the communication module and the host computer. Also the data acquisition units controlling the digital sensors were developed based on the LPC1768 MCU. In the whole monitoring system, theses data acquisition units functioned as the bottom nodes, which receiving commands from the host computer, collecting sampled data from various sensors and sending data back to the host computer in real time. Considering the reliability of the measuring system, advanced digital sensors from Decagon were selected in this system, which could measure the soil's temperature, water content, electric conductivity (EC), water potential, etc. These digital sensors with very low power requirements and excellent specifications, connected with the data acquisition units by RS232 interface with 150ms measurement time. Meanwhile, the host computer controlled these data acquisition units via RS485 communication interfaces adopting MODBUS protocol. So under this working mode, theses intelligent units worked in the RTU mode. The measurement system of the seepage and the control system of the drainage were also designed based on the LPC1768 MCU, which connected with the host computer via the RS485 communication interfaces. Considering the actual needs of remote monitoring, a flexible and economical GPRS module with RS485 interface was adopted to let the host computer report its state periodically to the operators via short message. The host computer system consisted of an industrial personal computer and the measure-control software which was developed with LabVIEW and had characteristic of the friendly human-computer interface. In this software, the sensor's type, quantity and sampling parameters could be configured. Meanwhile, flexible signal processing algorithms, including timed loop technique, moving averaging and median filter, were adopt to improve the accuracy further. Under this two-stage structure, the host computer controlled the whole systems, the data could be displayed and analyzed in real-time. The experimental results showed that the resolution of the Lysimeters was up to 0.0072mm.
Number of references:28
Main heading:Soil surveys
Controlled terms:ARM processors - Communication - Computer programming languages - Computer software - Control systems - Data acquisition - Evapotranspiration - Interface states - Lysimeters - Measurements - Seepage - Sensors - Signal processing - Soils - Water supply - Weighing
Uncontrolled terms:Agricultural productions - Data-acquisition units - Human computer interfaces - Industrial personal computers - LabViEW - Signal processing algorithms - Software and hardwares - System
Classification code:944 Moisture, Pressure and Temperature, and Radiation Measuring Instruments - 731.1 Control Systems - 801 Chemistry - 931 Classical Physics; Quantum Theory; Relativity - 932 High Energy Physics; Nuclear Physics; Plasma Physics - 941 Acoustical and Optical Measuring Instruments - 942 Electric and Electronic Measuring Instruments - 943 Mechanical and Miscellaneous Measuring Instruments - 943.3 Special Purpose Instruments - 723 Computer Software, Data Handling and Applications - 407 Maritime and Port Structures; Rivers and Other Waterways - 441 Dams and Reservoirs; Hydro Development - 444.1 Surface Water - 721 Computer Circuits and Logic Elements - 446.1 Water Supply Systems - 716 Telecommunication; Radar, Radio and Television - 716.1 Information Theory and Signal Processing - 483.1 Soils and Soil Mechanics
DOI:10.3969/j.issn.1002-6819.2013.16.017
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679253
Title:Numerical simulation of solid-liquid suspension characteristics for low-density particles in stirred vessel
Authors:Li, Liangchao (1); Yang, Jun (1); Xu, Bin (1)
Author affiliation:(1) Key Laboratory of Testing Technology for Manufacturing Process of Ministry of Education, Southwest University of Science and Technology, Mianyang 621010, China
Corresponding author:Li, L.(tchllc@126.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:42-49
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:Low-density particles solid-liquid suspension characteristics are very critical problem in stirred vessels industrial process. Solid-liquid suspension characteristics for low-density particles in a dual six-blade-Rushton-turbine(6-DT) impeller stirred vessel was simulated numerically by using computational fluid dynamics (CFD). The multiple reference frame (MRF) and Euler-Euler two fluid model based on the kinetics of granular were used in the simulation. Flow field and solid holdup distribution in the stirred vessel were obtained and realized visualization. Furthermore, the influences of the operating condition on solid-liquid suspension were investigated. The simulated results are in good agreement with experimental data in the literature, which verified the feasibility of our numerical method. The research results show that the flow pattern in a dual-radial-impeller stirred vessel was closely related to the clearance of the two impellers. When the clearance is greater or equal to a half diameter of the vessel, parallel flow will form, since the effect among the circulation flows is less. A typical double circulation pattern is formed for every disc turbine, and there are four circulation loops in the stirred vessel. Liquid velocity decreases slightly with low-density particles adding to the vessel. On the whole, solid holdup increases along the axial height. The highest solid concentration is found in the center of the liquid surface region for low-density particles which easily accumulate there, while the lowest solid holdup is in the center of the bottom region. Solid holdup in the center of the circulation loops and behind the blades is relatively high. The phenomenon of solid holdup regional distribution is also observed in the dual-radial-impeller stirred vessel. Taking the height of h=0.5T as a boundary, the vessel can be subdivided into upper region and lower region, and solid holdup in upper region is obviously higher than that in lower region. With the increasing of impeller speed, solid holdup in the liquid surface region and upper region decreases significantly, while it increases in lower region of the stirred vessel. Solid suspension is even for very small size particles. The uniformity of solid suspension worsened with the increasing of particles size or the reducing of impeller speed. The effect of particles content on solid suspension is not very obvious. The study can provide helpful references for design, optimization, and scale-up of the stirred vessel for low-density particles suspension.
Number of references:28
Main heading:Suspensions (fluids)
Controlled terms:Computational fluid dynamics - Impellers - Liquids - Numerical analysis - Particles (particulate matter) - Solids - Structural frames - Turbines - Turbomachine blades
Uncontrolled terms:Circulation patterns - Low-density particles - Multiple-reference frames - Regional distribution - Small size particles - Solid concentrations - Solid-liquid suspension - Stirred vessels
Classification code:931.2 Physical Properties of Gases, Liquids and Solids - 921.6 Numerical Methods - 804 Chemical Products Generally - 951 Materials Science - 618 Compressors and Pumps - 601.2 Machine Components - 408.2 Structural Members and Shapes - 612.3 Gas Turbines and Engines
DOI:10.3969/j.issn.1002-6819.2013.16.006
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679276
Title:Integration method of accomplishments of arable land from province level to national level based on equal standard crop yields
Authors:Kong, Xiangbin (1); Zhang, Qingpu (1); Yun, Wenju (2); Wang, Hongbo (2); Tan, Min (1); Zhao, Jing (1)
Author affiliation:(1) College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China; (2) Key Lab for Arable Land Quality, Monitoring and Controing of National Ministry of Land Resources, Beijing 100193, China; (3) Land Consolidation and Rehabilitation Center, Ministry of Land and Resources, Beijing 100035, China; (4) Beijing Fang Yuan Da Di Planning and Design Consulting Co., Ltd., Beijing 100193, China
Corresponding author:Kong, X.(kxb@cau.edu.cn)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:238-246
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:China, the fastest developing country with the highest population in the world, is undergoing the most rapid industrialization and urbanization in the human history. Thus, the country faces multiple challenges of food insecurity including conversion of prime agricultural land to urban encroachments, limited land resources available for crop production, lack of adequate amounts of fresh water for irrigation and urbanization/industrialization, and increasing risks of climate change and the associated extreme events. Therefore, how to accurately evaluate the potential productivity of arable land at the present technology at national level is very important to identifying yield gap of arable land, and to regulating scientific policy to close yield at national level. China has accomplished arable land grading at national level, and the accomplishments of Chinese national arable land grading at plot level not only pushed the advance in the science and technology of land evaluation, but also provided accurate data basis for management of arable land protection in China based on arable land quantity and quality. The key technique developed in the accomplishment of Chinese national arable land grading was adopted in the arable land grade transferring from provincial to national level. Thus, analyzing the accuracy of the method is very important for identifying the scientific method and providing useful tool for the arable land grading at different levels. The database of arable land grade in 12 provinces and the standard crop yields from a sample of 13, 302 at plot level were employed to the compared analysis. The results presented in the article indicated the following:1)the balance transferring method based on the standard crop yields of arable land could fulfill the achievements in arable land grade conversion from provincial to national level; 2) the accuracy of the arable land grade at provincial level was the principal result of this method; 3) the scientific calculation of the standard crop yields of arable land was critical factor to the accuracy of the method; 4) the accomplishments of arable land grade in the western of 12 provinces at national level were in accordance with the characteristics of distribution of productivity of arable land. The method of the balance transferring based on the standard crop yields of arable land grade could be used for different levels such as county's and provincial levels.
Number of references:31
Main heading:Land use
Controlled terms:Climate change - Cultivation - Developing countries - Grading - Productivity - Quality control - Transfer functions
Uncontrolled terms:Arable land - Crop yield - Integration method - Potential productivity - Science and Technology - Scientific calculations - Scientific method - Transferring method
Classification code:921 Mathematics - 913.3 Quality Assurance and Control - 913.1 Production Engineering - 901.4 Impact of Technology on Society - 821.3 Agricultural Methods - 451 Air Pollution - 403 Urban and Regional Planning and Development
DOI:10.3969/j.issn.1002-6819.2013.16.030
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133516679278
Title:Technical efficiency analysis on non-wood forest products managed by SLCP households
Authors:Xue, Caixia (1); Yao, Shunbo (1); Yu, Jinna (1); Li, Hua (1)
Author affiliation:(1) Center for Resource Economics and Environment Management, Northwest A and F University, Yangling 712100, China
Corresponding author:Yao, S.
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:255-263
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:The Sloping Land Conversion Program (SLCP) was launched by the Chinese government in 1999 with environmental goals of reducing soil erosion and desertification and increasing the country's forest and grassland cover by retiring steeply sloping and marginal land from agricultural production. The SLCP has converted 8.20 million hectares of cropland to forest, and more than 32 million households participated in SLCP through the end of 2007. According to the article 4 in SLCP Regulation, the ecological service is the first principle of SLCP. Therefore, the non-timber forest products (NTFPs) management is one of the land-use options that SLCP households might choose. Generally, there are two alternatives of NTFPs management, one is the commercial forests management, including fruit trees, nut fruit trees, tea, woody medicine, etc.; the other is understory planting and livestock breeding in the understory, including grains, vegetables, grass, fungus, medicine, chicks, etc. The technical efficiency will be different if SLCP households adopt different NTFPs management options. The objective of this paper is to analyze the technical efficiency of households' NTFPs management considering the different management options. Stochastic Frontier Analysis (SFA) is one of the approaches for technical efficiency analysis, which assumes that the production technology is the same for all production units. However, there are some unobserved differences in technology that might be inappropriately labeled as inefficiency if such variations in technology are not taken into account. Therefore, we use a latent class stochastic frontier model (LCSFM) combined with the SFA and a latent class structure to account for this heterogeneity. The Trans-log function is adopted in LCSFM finally through a series test, and the seedling and labor input are considered as the criteria of technology class. The empirical analysis is conducted by using 235 households' survey data from Ya'an City Sichuan Province, and some important results are revealed. First, there are four technical classes on the different technology frontier and the technical efficiency of them can be listed in the descending order, i.e. class of livestock breeding and medicine in the understory, class of fruit and woody medicine, class of grains and vegetables in the understory, and class of nut fruit,. Secondly, the technical efficiency of all households' NTFPs management increased from 0.5393 in 2008 to 0.5572 in 2011. Except for the class of grains and vegetables in the understory, all other classes showed the same increase trend. To that end, we estimated the factors' elasticity of different classes, and held that it is the elasticity different that explains why SLCP households are divided into different classes. Therefore, some policy implications are given in order to improve the technical efficiency of SLCP households' NTFPs management. First, the government should actively disseminate forestry technology information and train the farmers through different channels. Secondly, the R&D activities and forestry machinery popularization should be promoted, because mechanization greatly contributes to the forestland productivity. It is hoped that these efforts will be contributed to improve the SLCP.
Number of references:31
Main heading:Forestry
Controlled terms:Efficiency - Elasticity - Engineering education - Fruits - Machinery - Management - Orchards - Production - Public policy - Stochastic models - Stochastic systems - Technology - Timber - Vegetables
Uncontrolled terms:Agricultural productions - Forest products - Household - Non-timber forest products - Non-wood forest products - Production technology - Stochastic frontier analysis - Stochastic frontier models
Classification code:961 Systems Science - 922.1 Probability Theory - 913.1 Production Engineering - 912.2 Management - 901.2 Education - 971 Social Sciences - 901 Engineering Profession - 601 Mechanical Design - 422 Strength of Building Materials; Test Equipment and Methods - 421 Strength of Building Materials; Mechanical Properties - 415.3 Wood Structural Materials - 821 Agricultural Equipment and Methods; Vegetation and Pest Control
DOI:10.3969/j.issn.1002-6819.2013.16.032
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

Accession number:20133616700633
Title:Optimal spatial scale for crop-weed discrimination
Authors:Li, Ying (1); Chen, Huailiang (1)
Author affiliation:(1) CMA Henan Key Laboratory of Agrometeorological Support, Applied Technique, Zhengzhou 450003, China; (2) Henan Institute of Meteorological Sciences, Zhengzhou 450003, China; (3) Henan Meteorological Administration, Zhengzhou 450003, China
Corresponding author:Chen, H.(H.chen@vip.163.com)
Source title:Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering
Abbreviated source title:Nongye Gongcheng Xuebao
Volume:29
Issue:16
Issue date:August 15, 2013
Publication year:2013
Pages:159-165
Language:Chinese
ISSN:10026819
CODEN:NGOXEO
Document type:Journal article (JA)
Publisher:Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South, Beijing, 100026, China
Abstract:In recent years, remote sensing images obtained by different types of optical sensors from a ground platform are applied to crop-weed discrimination and serve variable-rate technology in precision agriculture. Classification accuracy in remote sensing is influenced by spatial scale, so choosing the optimal spatial scale can be helpful for field data acquisition. Influences of spatial scale on classification accuracy in remote sensing are mainly originated from two factors: one factor is mixed-pixel and the other factor is spectral variability. Both aggravated mixed pixel caused by a larger spatial scale and aggravated spectral variability caused by a smaller spatial scale will result in classification accuracy reduction in remote sensing. For geographic entities in remote sensing images have inherent spatial attribute and spectral attribute, a spatial scale exists which can minimize the net effect of both mixed-pixel and spectral variability. Under this spatial scale, pixels can have optimal spectral identifiability. An approach for the selection of optimal spatial scale using a spectral angle mapper to measure the net effect of both mixed-pixel and spectral variability was proposed for crop-weed discrimination. The basic thinking of optimal spatial scale selection based on spectral angle mapper is as follows: using the average spectra calculated from a great amount of pure pixels belonging to one kind of ground object as the reference spectra for this kind of ground object, the spectra of each pixel could be regarded as the sum of its reference spectra and the net effect of mixed-pixel and spectral variability. Then, the spectral angle between the pixel spectra under different spatial resolutions and its reference spectra might be calculated to measure the net effect of mixed-pixel and spectral variability. The pixel will have optimal spectral identifiability when the net effect is least, and in this case, the spatial scale is the optimal scale. The proposed approach was realized in one field image. The geographic entities in the image were objectified. The optimal spatial scale was 0.48 cm by using the spatial scale selection method based on a spectral angle mapper. The relationship between the area and shape indexes of the target object and its optimal spatial scale was analyzed theoretically. For other field scenes, the finding can provide a reference for optimal spatial scale selection by calculating the area and shape indexes of plant objects.
Number of references:35
Main heading:Pixels
Controlled terms:Classification (of information) - Crops - Image reconstruction - Optimization - Remote sensing - Spectrum analysis
Uncontrolled terms:Classification accuracy - Field data acquisition - Mixed-pixel - Precision Agriculture - Remote sensing images - Spatial scale - Spectral angle mappers - Variable rate technology
Classification code:944 Moisture, Pressure and Temperature, and Radiation Measuring Instruments - 943 Mechanical and Miscellaneous Measuring Instruments - 942 Electric and Electronic Measuring Instruments - 941 Acoustical and Optical Measuring Instruments - 921.5 Optimization Techniques - 921 Mathematics - 821.4 Agricultural Products - 741 Light, Optics and Optical Devices - 731.1 Control Systems - 723.5 Computer Applications - 716.1 Information Theory and Signal Processing
DOI:10.3969/j.issn.1002-6819.2013.16.020
Database:Compendex
Compilation and indexing terms, Copyright 2013 Elsevier Inc.

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