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Dong Z.,ShenYang Agricultural University | Dong Z.,Chinese Academy of Agricultural Sciences | Li S.,Chinese Academy of Agricultural Sciences | Yan H.,Modern Agricultural Equipment Co. | And 5 more authors.
International Agricultural Engineering Journal | Year: 2014

A variable step conveyer was designed for precisely feeding tray seedlings on the high efficiency transplanters. The tray seedlings are transported by an automatic feeding system to the target location, and pushed out row by row by an ejector bar in the back of the tray. The seedlings are then taken and put into the transplanting mechanism. A gas-liquid damping cylinder was used as the actuator in this device. The feeding system was controlled by PLC with a stepper motor that made it adaptable to different tray sizes. The development of the conveyer was introduced and the major parameters were determined through structure analysis. Performance evaluation tests were conducted to investigate the positioning of the system driven by the damping cylinder. The results indicated that the variable step conveyer had a high stability greater than 98.5%, but also had some systematic lags which will require a compensation module. Source

Hua Y.,Modern Agricultural Equipment Co. | Jianmin W.,State Key Laboratory of Soil Plant Machinery System Technology | Junping Z.,Modern Agricultural Equipment Co. | Xingning Z.,Agricultural Machinery Identification Station | And 3 more authors.
International Agricultural Engineering Journal | Year: 2013

A number of tests were required to evaluate the technical and economic indicators of handheld tillers, including performance, reliability, security and economy, and also tests to improve machine's quality and optimize the designs. Traditional field tests are restricted by many factors. In order to improve testing precision and make testing less labor intensive, a testing platform wim annular soil bin was established indoors, and a flexible clamp mechanism and control system was designed. The structure of clamp mechanism and the relationship between the mechanism and the testing platform was described. The mechanism must satisfy the three requirements in order to maintain automatic control of tilling depth. Firstly, a geometric model of tilling depth control for handheld tiller was established. The position of handheld tiller was then determined by angle sensor and encoder. Finally, the elevator mechanism of the trolley was loop controlled so that the height of handles could be adjusted automatically allowing the tilling depth of handheld tiller to be controlled automatically. The clamp device was adjustable in three-dimensions, and could be adapted to different specifications of handheld tiller's handles. The experimental results indicated that the coefficient of stability of automatic tilling depth control with the flexible clamp system was greater man 80%, and the system completely met the experimental requirements for the handheld tiller. Source

Li H.,China Agricultural University | Wei W.,China Agricultural University | Dong X.,China Agricultural University | Fang X.,State Key Laboratory of Soil Plant Machinery System Technology
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2010

In order to study the mesh problem in case that the surface is generated by curvilinear cutter with two degrees of freedom a theory of surface generated by curvilinear cutter edge with two degrees of freedom is put forward by using the conjugate conditions of two degrees of freedom motion. The theory is used to calculate the helical surface of the toroidal worm generated by linear cutter edge whose relative motion has two degrees of freedom. This kind of worm is manufactured on a hob machine and its helical surface of the worm is measured on a CMM. The application prospect of this kind of worm gears is studied. The conclusions are: by using the theory the generate curved surface can be deduced when the curvilinear cutter edge and the varying regularity of the two motion parameters are given or the varying regularity of the two motion parameters can be derived when the generated curved surface and the curvilinear cutter edge are given; the calculation of the curved surface generated by curvilinear cutter edge with two degrees of freedom can be simplified if the varying regularity of the two motion parameters is restricted properly; the "modification" curve of the worm generated by linear cutter edge with two degrees of freedom is close to that of the hindley worm which is modified in parabolic curve; the defect of the hindley worm gears can be avoided by using this kind of worm gears without needing modification and there is a good application prospect. ©2010 Journal of Mechanical Engineering. Source

Ma Y.,Jilin University | Ma Y.,State Key Laboratory of Soil Plant Machinery System Technology | Pei G.,Jilin University | Wang H.,Jilin University | And 3 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015

As a kind of typical natural biological material, mammalian teeth have formed the optimized geometry with excellent mechanical properties after a long period of evolution, and have occupies an important position in the field of engineering bionics. Biological tribology is a new cross subject, which involves extensively, such as medicine, materials science, biology, tribology, mechanics, and is mainly divided into 2 categories i.e. human biological tribology and bionic tribology. Teeth tribology is a branch of biological tribology. The study object of modern tooth tribology is divided into 2 major categories i.e. human and animal. The research of human tooth friction is mainly concentrated in the medical field. The main purpose of the research is to master the mechanism of the friction and wear, minimize the irreversible damage of the tooth in the occlusion process and service human oral health. The research and application of animal tooth friction is mainly in engineering field, and a series of studies have been carried out in recent years. Studies on mechanical properties of the mammalian teeth mainly use nano-mechanics test and Vickers hardness test. Taking the teeth of dogs, pigs and deer as the research objects, the friction and wear behavior of the 3 different animal teeth was investigated systematically in this paper. The wear resistance of the 3 teeth surfaces was estimated by a wear tester and a roughness tester. The structure of different worn surfaces was characterized by the scanning electron microscopy (SEM), and the mechanical properties such as hardness and elastic modulus were also evaluated by using a nano-test apparatus. Hardness is the ability of material to resist the pressure of hard objects onto its surface, which is the inherent property of the material, and the tribology properties of materials depend on its hardness to a certain extent. Research results showed that wear debris peeling off from the surface of dog enamel was serious. The surface was attached with a lot of fine abrasive particles and had obvious cracking phenomenon. The wear volume was 1.91×107 μm3. The surface of pig enamel showed mainly wear debris peeling, and the wear volume was 1.56×107 μm3. Compared with the pig teeth, the worn surface of the deer teeth enamel also showed wear debris peeling, but the wear degree was lower, and the wear volume was 1.39×107 μm3. The results also showed that the friction and wear properties of different teeth were closely related with hardness. The wear resistance, hardness and elastic modulus of deer tooth enamel were the largest, and that of dog tooth enamel was the smallest. The higher the hardness of enamel, the better the wear resistance, the less the wear debris, and the smaller the enamel wear. The larger the elastic modulus of enamel, the smaller the wear volume. Compared with dog molars and pig molars, deer molars have good characteristics on the tribology properties and mechanical properties, which illustrates that the tooth abrasion resistance of herbivore molars is better than that of predator and omnivore. This paper reveals the relationship between the abrasion resistance and the nano-hardness and elastic modulus of 3 animals' molars, which provides the basis of experiment data and theoretical basis for the study of the tribology properties of animal teeth in the future and also provides a reference for the design of a new type of agricultural soil-contacting component with high wear resistance. ©, 2015, Chinese Society of Agricultural Engineering. All right reserved. Source

Yu Y.,Zhejiang University | Yu Y.,State Key Laboratory of Soil Plant Machinery System Technology | Li Z.,Zhejiang University | Pan J.,Zhejiang University | Pan J.,State Key Laboratory of Soil Plant Machinery System Technology
PeerJ | Year: 2016

Objective. The objective of this study was to investigate changes in pigment, spectral transmission and element content of chicken eggshells with different intensities of pink pigment during the incubation period. We also investigated the effects of the region (small pole, equator and large pole) and pink pigment intensity of the chicken eggshell on the percent transmission of light passing through the chicken eggshells. Method. Eggs of comparable weight from a meat-type breeder (Meihuang) were used, and divided based on three levels of pink pigment (light, medium and dark) in the eggshells. During the incubation (0-21 d), the values of the eggshell pigment (ΔE, L*, a*, b*) were measured. The percent transmission of light for different regions and intensities of eggshell pigmentation was measured by using the visible wavelength range of 380-780 nm. Result. Three measured indicators of eggshell color, ΔE, L* and a*, did not change significantly during incubation. Compared with other regions and pigment intensities, eggshell at the small pole and with light pigmentation intensity showed the highest percent transmission of light. The transmission value varied significantly (P < 0:001) with incubation time. The element analysis of eggshells with different levels of pink pigment showed that the potassium content of the eggshells for all pigment levels decreased significantly during incubation. Conclusion. In summary, pigment intensity and the region of the eggshell influenced the percent transmission of light of eggshell. Differences in the spectral characteristics of different eggshells may influence the effects of photostimulation during the incubation of eggs. All of these results will be applicable for perfecting the design of light intensity for lighted incubation to improve productivity. © 2016 Yu et al. Source

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