Time filter

Source Type

Zhao Z.,South China Agricultural University | Zhao Z.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Shi L.,South China Agricultural University | Liu X.,South China Agricultural University | And 3 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2015

Kinematics model of mechanical hydraulic system usually involves the speed, acceleration and geometric constraint, which will contain one or two and even higher order differential equations. The number of differential-algebraic equations (DAEs) increases with the increase of system complexity. In order to find a suitable control arithmetic, it is needed to figure out the relationship of different state variables. However, it's always impossible to get analytical solution. Thus it is needed to find the numerical solution of DAEs system, especially when it has too many state variables. Solving this problem with computer software is a common way; there are several helpful softwares, such as Matlab, Maple, Simulink and Mathematica. The mathematical function provided by the Matlab ode45 was used to solve the kinematics model of leveling system of paddy field leveler with sinusoidal input current. Firstly, the real paddy field leveler was simplified to kinematics model and showed in DAEs form based on theoretical mechanics and hydraulic theory. Secondly, the DAEs were changed into ODEs (ordinary differential equations). Finally, the ode45 was used to get numerical solution and show the relationship of state variables. The input current and output state variables were showed in figure. The method can help to get accurate numerical solution for DAEs system, and it also can display the relationship between the random input with known equations and other state variables. It will help to forecast the state variables at the next moment and design an efficient control algorithm for paddy field leveler. © 2015, Chinese Society for Agricultural Machinery. All right reserved. Source

Ma X.,South China Agricultural University | Ma X.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Tan Y.,South China Agricultural University | Qi L.,South China Agricultural University | And 4 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2016

At present, most of the work that taking trays out from the rice nursery seedling planter is completed one by one manually, which is labor-intensive and inefficient. There are some tray stackers can realize the function of automatic stacking, but the existing devices are only suitable for hard trays. Aiming at above problems, the automatic tray stacking device of rice precision seeding for nursing seedlings pipeline, suitable for both hard and soft trays, was developed to improve productivity and reduce labor intensity. According to the characteristics of common hard tray, the pallet of soft tray was developed for stacking. Besides, the transportation mechanism was designed through analyzing the conveying model. Based on the programmable logic controller (PLC), the trays were detected by a proximity switch of the control system, and the tray stacking mechanism was controlled to lift and drop the trays to achieved the tray stacking automatically(2~4 trays per stack is available). In addition, the cover plate of the soil anti-falling mechanism was controlled to lift after stacking and finally the device can effectively prevent the soil falling out of the tray in the process of stacking that lead to seeds exposed. For detecting the performance of automatic tray stacking device, the orthogonal experiment was carried out which regarded stacking success rate and seeds exposed rate as indexes and regarded the lifting speed of tray stacking mechanism, cover plate installation conditions and productivity as factors. Orthogonal experiment results showed that the lifting speed had more influence on success rate while the lifting speed and cover plate installation conditions had more influence on seeds exposed rate. When the lifting speed was 0.15 m/s, the cover plate installing with pneumatic cylinder and the productivity was 600~800 trays per hour, the stacking success rate of hard tray and soft tray was 100% and 99%~100% respectively while the seeds exposed rate was 0.28% and 0.60% respectively. The automatic tray stacking device can effectively raise productivity and reduce labor intensity, and the experimental indexes meet the using requirements of rice precision seedling. © 2016, Chinese Society of Agricultural Machinery. All right reserved. Source

Feng S.,CAS Institute of Subtropical Agriculture | Feng S.,University of Chinese Academy of Sciences | Feng S.,Huanjiang Observation and Research Station for Karst Ecosystems | Su Y.,CAS Institute of Subtropical Agriculture | And 17 more authors.
World Journal of Microbiology and Biotechnology | Year: 2015

Laccase enzymes produced by both soil bacteria and fungi play important roles in refractory organic matter turnover in terrestrial ecosystems. We investigated the abundance and diversity of fungal laccase genes and bacterial laccase-like genes in soil from subtropical arable lands, and identified which microbial group was associated with laccase activity. Compared with fungal laccase genes, the bacterial laccase-like genes had greater abundance, richness and Shannon–Wiener diversity. More importantly, laccase activity can be explained almost exclusively by the bacterial laccase-like genes, and their abundance had significant linear relationship with laccase activity. Thus, bacterial laccase-like gene has great potential to be used as a sensitive indicator of laccase enzyme for refractory organic matter turnover in subtropical arable lands. © 2015, Springer Science+Business Media Dordrecht. Source

Xiang W.,Hunan Agricultural University | Xiang W.,Hunan Provincial Engineering Technology Research Center for Modern Agricultural Equipment | Xiang W.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Wu M.,Hunan Agricultural University | And 7 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015

In order to resolve some key issues about the machinery of transplanter for rape seedlings, a new type of transplanter with crawler planting hole forming tools for rape was designed based on the working characteristic in the dry land and agronomic requirement. Research on soil physical and mechanical characteristics were conducted to provide the technical parameters for the design of the hole forming device. First, we completed the whole structure design and analyzed the working principle of the device. The crawler was drove by power system to go forward, on which the hole forming device was installed and synchronously moving. The surface cam was mounted on the chassis. As the caterpillar moved forward, the pore forming device installed on the track vertically stabbed into the soil under the pressure of surface cam supplied by body weight. As the tracks moved forward, the hole forming device was out of the surface cam profiling. As such, a plant hole was formed. We analyzed the curve of surface cam limit, confirmed the limited point so that a coordinate system was established. We then chose the definition curve interpolation method to solve the parameter equation of surface cam profiling combining with Matlab7.0 software plot function in the program and generated surface cam outline curve. For the optimization of punch mechanism of structural design, the surface cam profiling and reset spring control capacity into hole device unearthed vertically. The cylindrical hole was pressured by shearing and extrusion soil. We analyzed the same track number, it had two tracks. Each of them had two linear holes. When the machine moved forward, each side could dig holes in four rows at one time. We installed rolling bearing in the hole forming device for rolling friction instead of sliding friction to reduce friction in the cylindrical hole and the friction between the surface cams. By use of the prototype machine in field, we recorded variables, such as the time, moving distance, distance between holes, the depth of effective planting hole, and the diameter of planting hole. We analyzed indexes such as the rate of qualified hole, hole forming frequency, efficiency, etc.. The result showed that if the machine at lower speed at 1.65-1.78 km/h, the efficiency was up to 0.231-0.249 hm2/h, and the rate of qualified hole up to 93.8% on average. The various performance indicator met the design requirement. The planting and hole forming machine can get holes at 1 400 mm in length each, 50 mm in diameter, 50 mm in depth, and 120000 holes/hm2 in hole density per area. This could get the planting hole to satisfy agronomic requirement. The research provided theoretical and technical references for design of the new type of transplanter. ©, 2015, Chinese Society of Agricultural Engineering. All right reserved. Source

Luo X.,South China Agricultural University | Luo X.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Liao J.,South China Agricultural University | Hu L.,South China Agricultural University | And 5 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2016

Although great development has taken place in agricultural mechanization since reform and opening up, China still faces the big challenge in improving agricultural resource utilization as well as promoting the sustainable development of agriculture at present. As we all know, it is mainly the 5 factors, i.e. water, soil, fertilizer, pesticide and seed that affect sustainable development in the construction of China's agricultural modernization. The overall development of agriculture in China will be impeded if the resource utilization stays low. There exist some phenomena: 1) the irrigation water use is 360 billion m3 each year, while canal-system water use efficiency is only 0.4~0.6; 2) high-quality cultivated land is lacking; 3) nitrogen use efficiency is about 30%~35%, which is 20% less than developed country; 4) pesticide utilization is merely about 30%, while leads to severe environmental pollution; 5) the demand of seeding quantity is high while there are shortage of high-quality seeds and serious waste of seeds. Accordingly, several technologies and machines in PA (precision agriculture) were put forward in this article so as to meet the requirement of agricultural sustainable development: precision irrigation, precision plow, precision fertilization, precision spraying, and precision sowing. By reviewing the researches at home and abroad, the current situation of PA was analyzed and thus the methods to achieve the 5 mentioned key technologies were presented. Meanwhile, some other suggestions were proposed to push the agricultural mechanization to play a greater and more important role on the utilization of agricultural resource and agricultural sustainable development: 1) further strengthen the combination of agricultural machinery and agronomy as well as the basic study of related theory; 2) carry out in-depth studies on key technologies of maximum utilization of agricultural resource, especially in precision irrigation, precision plow, precision fertilization, precision spraying, and precision sowing; 3) enhance the capacity of independent innovation, namely, the capability of equipment design and manufacture related to PA; 4) accelerate extensive application of precision agricultural machine and equipment. Above all, this paper has provided a scientific guide and policy direction for improving utilization of agricultural resource, promoting agricultural mechanization and agricultural sustainable development. © 2016, Chinese Society of Agricultural Engineering. All right reserved. Source

Discover hidden collaborations