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| 1 | Determination of the coefficient of rolling friction of irregularly shaped maize particles by using discrete element method显示文摘The coefficient of rolling friction is a foundation parameter for conducting particles simulation,however,which of irregularly shaped maize seeds is difficult to measure.Furthermore,the coefficient of rolling friction between the simulation particles and the actual seeds is inconsistent due to the shaped difference of model and different position of gravity center.This paper use two methods to determinate the coefficient of rolling friction based on discrete element method(DEM)and physical experiments.Three types of maize models from five different shaped maize samples(including horse-tooth shape,spherical cone shape,spherical shape,oblate shape,irregular shape)were developed with the help of slice modeling and 3D modeling technology.Aluminum cylinder container is used to arrange the simulation experiments of angle of repose with taking the coefficient of rolling friction as independent variables and the simulation angle of repose as target values.After predicting detailed the coefficient of rolling friction(including horse-tooth shape,spherical cone shape,spherical shape,between horse-tooth shape and spherical cone shape,between horse-tooth shape and spherical shape,between spherical shape and spherical cone shape maize models),and forecasting a unified the coefficient of rolling friction among horse-tooth shape,spherical cone shape and spherical shape maize models,two types of materials(aluminum cylinder container and organic glass container)were used to validate the difference the angle of repose between the simulation maize models and actual maize seeds.Results show the relative error of the angle of repose between the maize models controlled by the coefficient of rolling friction through the detailed method and the actual maize seeds is 0.22%,0.33%in aluminum cylinder,organic glass container,respectively.The relative error of the angle of repose between the simulation maize models controlled by the coefficient of rolling friction through the united method and actual maize seeds is 2.47%,2.97%in aluminum cylinder,organic glass container,respectively.Although the difference of the angle of repose between two method is smaller,the detailed method is better.Moreover,From the accumulation process of the angle of repose we found that the difference on the contacts number between maize models and bottom plate,the change curve of the rotational kinetic energy,the potential energy of maize models controlled by the coefficient of rolling friction through the detailed and the united method are evidently.We can choose a better method to predict the coefficient of rolling friction of maize seeds according to the application situation and investigation objective of irregular maize seeds.The results can provide a theoretical basis for designing and optimizing the structure of the seed-metering machine with DEM. | Linrong Shi Wuyun Zhao Bugong Sun Wei Sun | 2020 | International Journal of Agricultural and Biological Engineering2020，13，2： | 5 |
| 2 | Effects of Structural Parameters on the Poisson’s Ratio and Compressive Modulus of 2D Pentamode Structures Fabricated by Selective Laser Melting显示文摘Metamaterials have been receiving an increasing amount of interest in recent years. As a type of metamaterial, pentamode materials (PMs) approximate the elastic properties of liquids. In this study, a finite-element analysis was conducted to predict the mechanical properties of PM structures by altering the thin wall thicknesses and layer numbers to obtain an outstanding load-bearing capacity. It was found that as the thin wall thickness increased from 0.15 to 0.45 mm, the compressive modulus of the PM structures increased and the Poisson’s ratio decreased. As the layer number increased, the Poisson’s ratio of the PM structures increased rapidly and reaches a stable value ranging from 0.50 to 0.55. Simulation results of the stress distribution in the PM structures confirmed that stress concentrations exist at the junctions of the thin walls and weights. For validation, Ti–6Al–4V specimens were fabricated by selective laser melting (SLM), and the mechanical properties of these specimens (i.e., Poisson’s ratio and elastic modulus) were experimentally studied. Good consistency was achieved between the numerical and experimental results. This work is beneficial for the design and development of PM structures with simultaneous load-bearing capacity and pentamodal properties. | Lei Zhang Bo Song Ruijie Liu Aiguo Zhao Jinliang Zhang Linrong Zhuo Guiping Tang Yusheng Shi | 2020 | Engineering2020，6，1： | 4 |
| 3 | Investigation of interaction effect between static and rolling friction of corn kernels on repose formation by DEM显示文摘The coefficient of static friction(SF),the coefficient of rolling friction(RF)for particles are two key parameters affecting the repose angle formation and flow characteristics.In this paper,the interaction effects of SF and RF on the formation process of corn repose angle was investigated by the discrete element method.Firstly,five shape kinds of corn models(horse tooth,spherical cone,spheroid,oblate,and irregular shape)were established.Secondly,aluminum cylinder and organic glass box were used to conduct the simulation experiments with taking SF and RF as independent factors and seeing the repose angle as dependent value.Based on simulation results the regression equations were established.Simulation results showed the relation between two factors and the rotational kinetic energy is not nonlinear,and SF does not significantly restrict the flow of corn models after increasing the flow direction,and the effect of SF on the contact number between corns and the bottom plate is remarkable,while the effect of RF on the contact number is not remarkable.Finally,the interaction effect of two factors on the repose angle was analyzed by variance analysis and results showed SF and RF all have a significant impact on the repose angle.Moreover,their interaction effect has an impact on the repose angle. | Linrong Shi Xiaoping Yang Wuyun Zhao Wei Sun Guanping Wang Bugong Sun | 2021 | International Journal of Agricultural and Biological Engineering2021，14，5： | 2 |
| 4 | CD4+T cells memorize obesity and promote weight regain显示文摘Body weight regain often causes failure of obesity therapies while the underlying mechanism remains largely unknown.In this study,we report that immune cells,especially CD4+T cells,mediate the‘memory’of previous obese status.In a weight gain-loss-regain model,we found that C57BL/6J mice with an obesity history showed a much faster rate of body weight regain.This obesity memory could last for at least 2 months after previously obese mice were kept at the same body weight as non-obese mice.Surprisingly,such obesity memory was abrogated by dexamethasone treatment,whereas immunodeficient Rag1−/−and H2A−/−mice failed to establish such memory.Rag1−/−mice repossessed the obesity memory when immune cells or CD4+T cells isolated from previously obese mice were transferred.Furthermore,depletion of CD4+T cells led to obesity memory ablation.Taken together,we conclude that CD4+T cells mediate obesity memory and promote weight regain. | Jianghuan Zou Beibei Lai Mingzhu Zheng Qin Chen Shujun Jiang Anying Song Zan Huang Peiliang Shi Xin Tu Di Wang Linrong Lu Zhaoyu Lin Xiang Gao | 2018 | Cellular & Molecular Immunology2018，15，6： | 2 |
| 5 | Analysis of the metering performance for typical shape maize seeds using DEM显示文摘The irregular shape,varying internal compositions,and uneven distributions of maize seeds can degrade the metering performance of maize seeders.This study investigates the effect of irregular maize on the performance of a high-filling-rate seed metering device using DEM.The results show that the seed population in the seed box formed large and small cycles of seed transport due to the disturbances caused by the three wheels.The increasing angular speed of the three wheels reduced the rate of seed filling in the seed filling regions by gravity and disturbances.In addition,an analysis of the repose angle formed by the dropped seed indicated that the angular speed of the taking seed wheel has a certain effect.The large angular speed reduced the coefficient of variation of the seed drop location.The repose angle of the horse tooth seed was greater than those of the other.Meanwhile,the irregular maize seed can also reduce the coefficient of variation of the seed drop location.A comparison between the simulation and experiment results indicates the number of metering seed were basically the same. | Linrong Shi Wuyun Zhao Wei Sun Xiaoping Yang Guanping Wang Shanglong Xin | 2023 | International Journal of Agricultural and Biological Engineering2023，16，1： | 1 |
| 6 | Effects of typical corn kernel shapes on the forming of repose angle by DEM simulation显示文摘Corn kernel shape is an important feature to improve the accuracy of simulation results,also the repose angle is often used to calibrate model parameters in simulation.In this study,the effects of the corn kernel shapes on the behavior during corn kernels accumulation were investigated in detail.Firstly,the DEM models of three typical shapes of corn kernels were developed.Secondly,the influences of the corn kernel shapes on the process of forming repose angle were investigated,such as corn kernels distance change,energy conversion,and the contact number between corn kernels.Results show that the corn kernel shape has a significant effect on the repose angle formation.The irregular shape of corn kernels limit their rolling when adding the corn kernel length in one or two directions.In addition,the irregular shapes of corn kernels increase the contact number and extend simulation time.Regular shape corn kernels need to be mixed with irregular shape corn kernels to improve their flowability.Finally,observation of the trajectory of corn kernel repose angles indicates that spherical corn kernels contact the bottom plate early,and forming small cone first,then the cone becomes bigger to change the direction of other corn kernels from top to bottom. | Linrong Shi Wuyun Zhao Xiaoping Yang | 2022 | International Journal of Agricultural and Biological Engineering2022，15，2： | 1 |
| 7 | Determination and analysis of basic physical and contact mechanics parameters of quinoa seeds by DEM显示文摘Quinoa is an ancient crop that is nutritious,balanced,and suitable for most people.However,it has not been known and sought by the public until modern times.In recent years,quinoa has been intensively known and widely grown in China.Quinoa mechanized production machines have also been developed.With the help of DEM,we design and optimize the quinoa combined seeder,improving seeding efficiency and quality.In this paper,the basic physical and contact mechanics parameters required for the Hertz-Mindlin(no slip)of quinoa seeds in EDEM software were determined.The coefficient of rolling friction of quinoa seeds was calibrated on DEM,and which of Long Quinoa 4 is 0.043,and that of Meng Quinoa 4 was 0.016.Meanwhile,we can find that the coefficient of rolling friction strengthens the shape to restrict rolling and weakens the shape to increase rolling.The above research provides simulation parameters for the design and optimization of quinoa seed seeding machinery. | Linrong Shi Wuyun Zhao Bugong Sun Wei Sun Gang Zhou | 2023 | International Journal of Agricultural and Biological Engineering2023，16，5： | 0 |
| 8 | Potato planter test bed based on capacitive precision seed-monitoring and miss-seeding compensation system显示文摘Potato seed-monitoring is the premise of its precise planting.But,for anti-dust,anti-vibration performance and durability,the existing photoelectric monitoring schemes have obvious congenital defects.So,a capacitive precision seed-monitoring idea was proposed in this study.Its theoretical basis is that the variation of dielectric between the capacitor plates will inevitably induce the fluctuation of the detected capacitance value.Therefore,the construction of a space capacitance sensor,and the acquisition of the net capacitance fluctuation caused by the seed spoon passing through the space area of the capacitor plates,were the core focuses of this study.Firstly,the system theory and working principle were introduced.Next,a space capacitance sensor that meets all the requirements was analyzed and constructed.And then,its spatial arrangement was described in detail,and most important of all,the technology roadmap of the net capacitance fluctuation measurement was put forward.For this purpose,MAX038 and GD32F407 were selected to work together to measure the capacitance.In this way,the top value of the space capacitance when a spoon passed through the space capacitance sensor was detected,at the same time,the corresponding grating encoder information was also recorded,so,the net capacitance fluctuation of this process was calculated.Based on this result,normal-seeding,miss-seeding,and multi-seeding were identified.More subtly,with the cooperation of the grating encoder,the position of the seed-metering monitoring point was configured freely.Just for miss-seeding,a predictive impact compensation concept was suggested.Based on the theories above,the software core links related to seed-monitoring and compensation control were analyzed.Finally,a potato planter test bed based on this study was built.Taking the Long-7 cutting potato as test samples,it was found that,the capacitance measurement error was no higher than 0.6%;no misjudgment on miss-seeding was found,however,for normal-seeding and multi-seeding,there was a small amount of identification of the opposite kind was found,but not more than 1.0%and 1.5%,respectively.Because of the flexibility of the seed-metering monitoring point layout,the predictive impact compensation can also be arranged according to actual needs,and the mechanism of the impact compensation system is simple and direct,which makes it cheap and fast.Nevertheless,a lower compensating seed potato tank filling rate is conducive to the average compensation success rate at an acceptable level.This research has laid the engineering foundation for the industrial application of potato non-photoelectric seed-metering monitoring and miss-seeding compensation. | Hua Zhang Wuyun Zhao Wei Sun Guanping Wang Xiaolong Liu Bin Feng Linrong Shi Yan Liu Hongling Li | 2022 | International Journal of Agricultural and Biological Engineering2022，15，6： | 0 |
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