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Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Compared with cars, buses and trucks, tractor often drives on the dirt road in the field of rural areas, together with the simple vibration damping device, so the vibration of tractor is particularly intense. Severe vibration of tractor would cause serious harm to driver's health, and cause fatigue and failure of tractor parts and hence seriously affect the life of the tractor. In addition, excessive vibration of the tractor will exacerbate farmland soil compaction and reduce crop yields. How to effectively reduce the vibration of tractors to improve ride comfort and driving safety and reduce farmland damage is an important research topic for researchers and tractor manufacturing enterprises. The study of foreign scholars have found when the tractor is installed with front axle suspension, the ride comfort and driving safety is improved. When farm tools hangs on the front of tractor, tractor damping effect depends on the matching between front axle suspension stiffness and damping coefficient. Installing the front axle suspension of tractor can significantly reduce tractor's pitching vibration. By the method of theoretical analysis, the theoretical system of front axle suspension of tractor was established, the vibration was analyzed and the theoretical formula was deduced, aiming to provide a theoretical basis for parameter matching of tractor front axle suspension. In this paper, CF700 tractor from Jiang Su Chang-Fa group was taken as the research object, and the theoretical model of front axle suspension tractor was established, including plane vibration model of front axle suspension tractor with 3 degrees of freedom, vibration differential equation and tractor vibration characteristics evaluation. Taking body vertical vibration acceleration, body pitching vibration angular acceleration, seat-mounted vertical vibration acceleration, front and rear wheels' dynamic load and front axle suspension dynamic deflection as the evaluation means, theoretical calculation method was adopted to optimize the matching of front axle suspension stiffness and damping coefficient, getting the best matching value between front axle suspension stiffness and damping coefficient (120 000 N/m, 8 000 N-s/m). Calculate and compare the vibration characteristics of the tractors installed with and without front axle suspension. When the tractor traveled on the roads of Grade D in international standard with the speed of 3-18 km/h, the root mean square values of body vertical vibration acceleration and pitching vibration angular acceleration of the tractor installed with front axle suspension averagely decreased by 24.03% and 42.46%, respectively, and those of seat-mounted vertical vibration acceleration and front wheel's dynamic load averagely decreased by 29.77% and 21.72%, respectively. The results show that the tractor installed with front axle suspension plays significant role to improve ride comfort and driving safety. The findings provide a theoretical basis and a certain reference value for the design and optimization of tractor front axle suspension. [ABSTRACT FROM AUTHOR]

A large amount of maize stalks are produced each year, due to the maize is serving as one of the main grain crop in China. Maize straw retention to the field after chopped is widely used in most disposal approaches. However, the currently used single shaft maize stalk chopping and retention machine can not meet the quality requirements of stalk chopping, such as too long maize stalk after chopping, and the low chopping pass rate of maize stalk, particularly when the amount of maize stalk was large, while the scarf skin of maize stalk was toughness. The shortcoming of maize stalk chopping directly determines the next seeding production, seed germination, and final crop yield. This paper aims to propose a novel chopping method, and thereby to design a double rollers type stalk chopping and retention device with different rotation speed and dynamic double support. The device mainly included the shell, supporting plate, suspension device, gearbox, transmission, chopping and collecting blade, shaft of chopping, collecting blade, blade shaft of slide-cutting supporting blade, and slide-cutting supporting blade. In operation, the chopping and collecting blade with anticlockwise rotation, firstly collected and chopped maize stalk in the field; then the maize stalk was chopped in dynamic support of side-cutting supporting blade with same rotation direction of chopping and collecting blade. A mechanical analysis of maize stalk was conducted under the effect of chopping and collecting blade, as well the slide-cutting supporting blade. The results showed that the rotation speed of chopping and collecting blade, and the slide-cutting angle of slide-cutting supporting blade were the main factors to affect the stalk chopping process. Furthermore, a motion analysis of chopping and collecting blade was carried out, including two L-type blades and a straight blade. The results revealed that the bend angle and length along the cutting-edge of L-type blade, and the rotation speed of chopping and collecting blade, were the main factors to affect the unpicking rate of maize stalk, and chopping pass rate, when the number of chopping and collecting blade and operation speed of device were fixed. In the slide-cutting supporting blade, the cutting-edge curvilinear equation was in the form of the logarithmic spiral equation. Moreover, the range of slide-cutting angle was 30º-60º, due to the slide-cutting angle can be more than frictional angle between maize stalk and slide-cutting supporting blade, according to slide-cutting principle. Importantly, the cutting edge of slide-cutting supporting blade with sawtooth was designed to increase the fraction of maize stalk and slide-cutting supporting blade. Prior to accurately coordinating between chopping and collecting blade, and side-cutting supporting blade, the rotating speed range of chopping and collecting blade was determined as 1 150 -2 500 r/min, to ensure the high stalk chopping pass rate. The rotation speed of slide-cutting supporting blade was one half that of chopping and collecting blade, to guarantee the speed of backward spread of chopped maize stalk. Simultaneously, the chopping and collecting blade, and side-cutting supporting blade, both were double helix arrangement to reduce machinery vibration, while increase machinery life. One device was installed 20 chopping and collecting blades, and 40 slide-cutting supporting blades. A quadratic rotation orthogonal combination test was used in the field research, to obtain the optimal structure parameters, where the chopping pass rate of maize stalk was set as test index. Some test factors were selected, including the cutting-edge bend angle of L-type blade (20º ≤γ≤60º), and cutting-edge length of L-type blade (30 mm ≤k≤60 mm), rotation speed of chopping and collecting blade (1200 r/min≤nY≤2 000 r/min), and slide-cutting angle of slide-cutting supporting blade (30°≤τ≤60°). The Design-Expert 8.0.6 software was applied to analyze the double factors interaction on stalk chopping pass rate, thereby to obtain the regression model between test factors and index. The primary and secondary factors that affect the maize stalk chopping pass rate were the rotation speed of chopping and collecting blade, the length of cutting-edge bend angle, the cutting-edge length of L-type blade, and the slide-cutting angle. In multiple objective optimization, the optimum ranges can be achieved, including the cutting-edge bend angle of L-type blade (41º≤γ≤57.64º), the cutting-edge length of L-type blade (41.7 mm≤k≤51.71 mm), the rotation speed of chopping and collecting blade (1 657.37 r/min≤nY≤1 889.97 r/min), and slide-cutting angle of slide-cutting supporting blade (36.55º ≤τ≤ 49.08º). In the field test, the rotation speed of chopping and collecting blade, the length of cutting-edge bend angle, and cutting-edge length of L-type blade, and slide-cutting angle were set as 1700 r/min, 40º, 45mm, and 45º, respectively. The field test results demonstrated that the maize stalk chopping pass rate was 92.58% under the optimal working parameters, while the error with the predictive value (93.96%) was less than 5%, indicating the reliable optimization of parameters. The finding can offer a sound reference to improve the chopping quality of maize stalk in the chopping and retention machine. [ABSTRACT FROM AUTHOR]

The air flow and temperature in the vegetable aeroponics cultivation box play an important role in the internal environment regulation and crop growth. The uniform air flow around crops can promote the growth rate of the crop. In order to study the distribution of flow field and temperature field in vegetable aeroponics cultivation box, CFD models of vegetable aeroponics cultivation box under different air flow circulation modes were established based on computational fluid dynamic (CFD) method, FLUENT software, standard turbulence model, porous medium model, crop canopy heat exchange model. The environment in the aeroponics cultivation box was optimized, and three air flow circulation schemes were designed(air flows from top to side, side to top and side to side). The layout of the different positions of the return air outlets was studied, and the numerical simulations of the three air flow circulation schemes were carried out. The simulation results showed that in the scheme of air flow entering from the top and exiting from the side, the suitable wind speed value area of lettuce accounts for 58.1%, the suitable temperature value area accounts for 93.6%, and the ventilation dead zone area accounts for 0.844%. In the scheme of air flow side entering and exiting the top surface, the suitable wind speed value area of lettuce accounts for 59.6%, the suitable temperature value area accounts for 99.98%, and the ventilation dead zone area accounts for 0.069%. In the scheme of air flow side entering side exit, the suitable wind speed value area for lettuce growth accounts for 54.3%, the suitable temperature value area accounts for 92.4%, and the ventilation dead zone area accounts for 16.7%. After comparison, the side entering the top surface was obtained as the optimal air circulation scheme. The temperature and wind speed simulation values and measured values in the aeroponics cultivation box were compared. The results showed that the average temperature relative error was 3.9% and the root mean square error was 0.86°C. The average relative error of wind speed was 3.5%, and the root mean square error was 0.26 m/s. The error between simulated and measured values was small, and the simulation effect was good. The accuracy of the CFD model was verified. In crop cultivation, aeroponics was a new cultivation method in the field of soilless cultivation, which could be applied to greenhouses, plant factories, family balconies and other places through microclimate control technology. In this paper, by regulating the wind speed in the aeroponics box, the climate growth environment and temperature uniformity of the crops can be ensured, and the problems of the roots and canopies of the crops can be effectively solved, and the crop yield and quality can be improved. Airflow velocity and temperature are important factors for crop growth in aeroponics boxes, which affect the transpiration and photosynthesis of crops. Therefore, it is of great significance to study the changes of air velocity and temperature to promote air aeroponics technology. This study provides a reference for the flow field and temperature change law in vegetable aeroponics cultivation box, internal environment adjustment and device optimization design. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)