Abstract:China is the country of origin of Astragalus sinicus L., and also the country with the earliest utilization and cultivation of Astragalus sinicus L. and the largest planting area in the world. Astragalus sinicus L., also known as Chinese milk vetch, Zi yunying and so on, is one of the main winter green manure crops in paddy fields of central and southern China. Currently, the harvest methods of Astragalus sinicus L.green manure seed are mainly include: artificial harvest and mechanical harvest, artificial harvest is time-consuming and laborious, and the yield of reserved seed for planting is low. Generally, the seed yield of Astragalus sinicus L. in paddy field is 300~650kg/hm2, there are two common ways of mechanical harvest: the first one is segmented harvest, using a rice, wheat, rape or bean swather to harvest Astragalus sinicus L. and then through natural drying, a thresher is used for threshing afterwards, the second one is combine harvest, by adjusting parameters and changing working components of traditional grain harvester or rapeseed combine harvester to complete harvest of Astragalus sinicus L seed. Segmented harvesting process is cumbersome and inefficient, combine harvest is of high efficiency, which is the development trend of Astragalus sinicus L. seed harvest, however, the harvest quality of existing Astragalus sinicus L. green manure seed combine harvester was affected by unreasonable structure configuration of header, weak separation ability of threshing mechanism, and poor impurityremoval function of cleaning device, the loss rate of machine harvest in field measurement was in the range from 31.5% to 32.1%, and the seed impurity rate and breakage rate were high, which seriously affected the scale promotion and application of Astragalus sinicus L. green manure. In order to solve the problems such as poor applicability of header, weak separation ability of threshing mechanism and poor impurity-removal ability of cleaning device during the harvest process of existing-Astragalus sinicus L. green manure seed harvester, a 4LGM-200 type-Astragalus sinicus L. green manure seed combine harvester was designed. The Parameters of the key components, such as the flexible anti pod-dropping seedling-lifting header, the longitudinal rod teeth type threshing device and the air-sieve type layered impurity-controlled cleaning device were designed, the structual parameters (lenth of feeding section, threshin section and grass-dischaging section) of the longitudinal rod teeth type threshing device were determined. Meanwhile, the structural parameters, number and circumferential distribution of threshing elements were designed and calculated. Both the ICEM-CFD mesh partitioning software and Fluent fluid dynamics analysis software were used to perform numerical simulation on the internal airflow field of the threechannel centrifugal fan under the condition when the rotation speed of the fan was 1080r/min and impeller diameter was 385mm, and test verification analysis were carried out as well. Aiming at reducing loss rate, breakage rate and inpurity rate of Astragalus sinicus L. seed during mechanical harvest process, four factors which had a great influence on the harvest quality were selected, including the machine forward speed, rotation speed of the roller, rotation speed of the fan and the scale sieve’s opening. By adoting the Box-Behnken central composite test method, the response surfaces experiments with four factors and three levels were conducted, and then the response surface analysis of the test results was performed by using Design-Expert, through multi-objective parameter optimization, the best combination of working parameters was obtained: the machine forward speed was 3km/h, rotation speed of the roller was 550r/min, rotation speed of the cleaning fan was 990r/min, and the scale sieve’s opening was 35mm. Under these parameters, the field test was carried out, the results showed that the loss rate of Astragalus sinicus L. seed was 2.35%, the breakage rate was 0.22%, and the impurity rate was 0.51%, which was better than the technical requirements of loss rate and breakage rate less than 5% and impurity rate less than 3% specified in relevant standards. 

Abstract:The conventional vertical rape windrower, whose laying direction of the rape plants is perpendicular to the forward direction of the windrower, still has the challenge to guarantee stable feeding rate of the following pick-up operation due to the inconsistent laying angle, highlighting a need to change the way of laying. As a solution, a forward laying device for rape windrower, whose operation parameters were analyzed, was proposed and the simulation experiments was carried out to optimize the laying quality based on ADAMS. Focusing on the moving of the rape plant at the outlet of the header, the horizontal throwing movement of the plant and its following fixed axis rotation after landing at the ground were analyzed based on kinematics and dynamics, indicating that the laying angle was related to the initial velocity and fixed axis rotation time of the plant. It was found that the main factors affecting the laying quality were forward speed of the windrower, speed ratio of transverse conveyor chain, and inclination angle of the header. Furthermore, the laying process under the coordination of the wheel and the guide plate was analyzed. The number of wheel teeth was 7 while the rotational angular velocity was 6.27rad/s. In addition, the curve parameter equation of the guide plate was also determined, and a four-bar mechanism was designed. Based on ADAMS, a multi-body kinematic simulation model of the forward laying device was constructed. By taking the forward speed of the windrower, transverse transmission chain speed ratio and inclination angle of the header as factors, the laying angle was utilized to evaluate the laying quality in the Box-Behnken simulation experiment with three factors and three levels. The mathematical relationship model between the laying angle and every factor was obtained to figure out the optimization objective function to minimize the laying angle. With the assistance of the DesignExpert software, the optimal parameter combination was obtained, and then it was validated by simulation and field experiment. The results of the Box-Behnken experiment indicated that the optimal parameter combination was forward speed of 0.93m/s, transverse conveying chain speed ratio of 1.11, and inclination angle of 117.93°. The theoretical optimal laying angle was 15.25° under this condition. The results of the simulation experiment illustrated that the simulation value of laying angle was 14.42° under the optimal combination of parameters, and the relative error was 5.4% when compared with the theoretical value. The field experiment showed that the forward laying device could work smoothly without blockage. The average laying angle, average laying width and average laying height were 17.25°, 752mm and 323mm, respectively, which could meet the demand of actual production. The research could provide a reference for the structural improvement and optimization of the laying device for vertical rape windrower.

Abstract:The change of the feeding amount will cause the various working parts to be subjected to variable load impact and unbalanced force, resulting in a sudden change in the vibration of the combine harvester when it is working. Aiming at the stability and reliability of the combine harvester, based on the combine harvester motion balance equation and the correlation analysis method of the external vibration disturbance signal, the vibration acceleration signal of the main working parts under different feeding amounts was obtained by carrying out the variable feeding vibration test of the combine harvester under field conditions. When the fed grains exhibited strong damping characteristics, the vibration acceleration signal was decreased accordingly. However, when the power demand of the harvester was increased, it would further lead to the phenomenon of increased vibration signal. The acceleration signal measured by the test was processed by quadratic integration, and the acceleration signal was converted into a frequency domain signal by fast Fourier transform. The change of amplitude and the characteristics of excitation frequency were obtained. The vibration caused by the disturbance of the feeding amount mainly occurred in the low frequency excitation frequency range, and the damping characteristic of the feeding amount reduced the high frequency amplitude. The feeding amount had the most obvious effect on the vibration of the threshing drum, and the maximum amplitude was attenuated from 17μm to 2.8μm, and the change degree could reach 83.5%. The change degree of header and the conveying trough was 55.8% and 7.69%, respectively. The maximum peak point of the threshing drum also moved left from the mid-frequency near 195Hz to the low-frequency near 117Hz.

Abstract:Seed corn has much seed crushing and shedding losses during the peeling process, which seriously affects seed corn's yield and economic efficiency. Therefore, a combination of theoretical analysis, discrete element simulation, and orthogonal tests was used to investigate the interaction between the seed corn ears and the peeling mechanism. The optimal combination of peeling parameters was determined to optimize the peeling process of seed corn. Firstly, a theoretical analysis of the force and motion of the seed corn ear in the peeling mechanism was conducted to investigate the peeling mechanism-seed corn interaction during the peeling process and identify the main factors affecting the peeling performance. Secondly, a simulation model of seed corn ear-peeling mechanism interaction was established based on DEM. The better working range of peeling roller speed, peeling roller inclination angle, and pendulum swing were determined by analyzing the seed damage and shedding. Finally, according to the Box-Behnken design method, a three-factor, three-level orthogonal test was designed. The best combination of operating parameters for the seed corn peeling mechanism was screened by ANOVA and response surface analysis as follows: peeling roller speed of 300r/min, peeling roller inclination angle of 10°, and pendulum swing amplitude of 5°, at which the bract stripping rate was 94.13%, the grain falling rate was 1.564%, and the grain crushing rate was 1.292%. The optimal combination of operating parameters of the peeling mechanism obtained from the experiment significantly improved the peeling effect of seed corn. The research results can provide a reference for the optimal design of the seed corn peeling mechanism to enhance the peeling efficiency of seed corn and reduce the grain crushing rate and the grain falling rate during the peeling operation.

Abstract:Castor effluent has complex components, high impurity content and low efficiency after cleaning. There is no special cleaning device. A double-layer inclined vibrating air-screen castor cleaning device was designed. Firstly, the overall structure of the cleaning device was designed, and the double-layer wind blowing synchronous vibration structure was determined. Secondly, the key components of the device, such as vibrating screen, cleaning chamber and discharge port, were designed. The discrete element method (DEM) was used to optimize the structure of cleaning screen. The ZheBi No.4 varieties was taken as the test material, and then the discrete element parameters of the material were measured. Through the single factor test, the effects of the upper screen hole distribution, the screen hole size and the screen surface inclination on the screening efficiency and loss rate were analyzed. The optimum design parameters were determined as follows: the U-shaped mesh arrangement, the mesh diameter of 14mm, and the inclination angle of the screen surface of 8°. The parameters of the single objective function were optimized. When the vibration amplitude of the vibrating screen was 8.43mm, the vibration frequency of the vibrating screen was 6Hz, and the transverse angle of the air flow was 40°, the maximum screening efficiency of castor effluent was 98.20%. When the vibrating screen amplitude was 7mm, the vibrating frequency was 7.76Hz, and the transverse angle of air flow was 40.81°, the minimum loss rate of castor seeds was 2.02%. Through the single factor test, the effects of the distribution form, size and inclination angle of the upper screen surface on the screening efficiency and loss rate were analyzed, and then the best distribution form, size and inclination angle of the screen surface were determined. In order to obtain the optimal working parameters, the coupling method of discrete element method and computational fluid dynamics (CFD) was applied to simulate and analyze the cleaning process. Taking the amplitude, vibration frequency and transverse angle of air flow of vibrating screen as test factors, the screening efficiency and loss rate as test indexes, the ternary quadratic orthogonal combination test was designed. The mathematical regression model between each factor and index was established, and the parameters of the model were optimized. The results showed that when the amplitude of the vibrating screen was 9.00mm, the vibration frequency of the vibrating screen was 6.16Hz and the transverse angle of the air flow was 40.00°, the screening efficiency of the castor cleaning device and the loss rate of castor seeds were the best, which were 97.66% and 2.32% respectively. Through the bench test, the optimal parameter combination was tested. The actual efficiency and loss rate were 93.15% and 6.94% respectively, and the error with the predicted results was controlled within 5%. At the same time, the actual grain impurity content was 0.83%, which met the application requirements. The research result can provide a theoretical basis for the design of castor cleaning device.

Abstract:In order to explore the soil disturbance mechanism of the chisel plow and build a simulation model between viscous black soil and the tillage components, the operation effect was compared with subsoiling shovel and the micro disturbance mechanism and macro disturbance state of chisel plow on soil was studied, and a farming simulation model suitable for the soil in Northeast China was established. The simulation and test results showed that the subsoiling shovel sheared and destroyed the soil, lifted and fell the tillage layer and plow bottom layer, loosened the soil without turning over, and did not damage the original topsoil soil structure. The test value of soil swelling was 12.4%, the test value of soil disturbance coefficient was 59.4%, the disturbance area of longitudinal section was 52.586mm2, and the disturbance area of top view was 116.779mm2, the chisel plow compressed and destroyed the soil, ploughs the bottom soil to the surface, and destroyed the original plough soil structure. The test value of soil swelling was 14.1%, the test value of soil disturbance coefficient was 64.1%, the disturbance area of longitudinal section was 54.128mm2, and the disturbance area of top view was 233.061mm2. Compared with the data after subsoiling shovel operation, chisel plow can achieve more obvious soil disturbance effect. At the same time, the discrete element soil tillage model under the condition of heavy black soil in Northeast China was established. The Hertz-Mindlin with JKR Cohesion model was selected as the soil contact model, and the technical parameters of the simulation model were determined. The simulation and the soil disturbance cross-sectional profile obtained from the test were basically fitted. The relative errors between the simulation value and the test value of soil bulkiness and soil disturbance coefficient were 17% and 4.4%, which can meet the data error range of simulation and simulation, which provided basic data for discrete element simulation analysis of soil tillage components in Northeast China.

Abstract:In order to discuss the influence of different subsoiling methods on root morphology and tobacco-curing characteristics of mountain tobacco, verify the actual effect of the new-type subsoiling shovel independently designed, and seek excellent measures for cultivating mountain tobacco, field tests were carried out by setting three treatments: improved subsoiling (NS), traditional subsoiling (TS) and no subsoiling (CK). The results showed that compared with traditional chisel-type subsoiling shovel, the soil disturbance coefficient was increased by 14.79 percentage points, the soil compactness was decreased by 53.95% and the change rate of soil bulk density was increased by 5.84% at 30cm underground after tillage. Compared with traditional subsoiling, the total root length, root surface area, root volume, plant height, stem circumference, leaf area index, maximum leaf length, maximum leaf width, underground dry matter weight, aboveground dry matter weight, yield and upper leaves of planted tobacco were increased by 33.80%, 30.41%, 45.67%, 18.36%, 10.72%, 16.53%, 4.02%, 2.15%, 28.26%, 18.28%, 6.43% and 4.11%, respectively at the early stage of maturity，the number of effective leaves increased by one leaf, the average price and output value was increased by 4.83% and 11.63%, respectively, while the above indexes were significantly improved compared with the control group without subsoiling operation. It was found that subsoiling can effectively improve the tillage structure of mountain tobacco fields in Yunnan Province, thus promoting the root growth of mountain tobacco, enabling the root to absorb more water and nutrients for the above-ground development, improving the dry matter weight of tobacco leaves and the economic performance. Independently designed type subsoiling spade and its supporting carrying machine had more remarkable effect on subsoiling operation in middle Yunnan Province.

Abstract:The current research on the maintenance strategy of agricultural equipment is mainly based on equipment failure data and degradation, which often cannot guarantee the task success of the equipment in a specific operation process, thus making it difficult to meet the requirements of modern agriculture for high task completion of agricultural equipment. To address this problem, a task-based maintenance strategy for agricultural machinery and equipment was proposed. Firstly, based on the correlation between the degradation state of each system of agricultural equipment and the task reliability of the equipment, an assessment model of the task reliability of agricultural equipment was established. Secondly, using the Monte Carlo method, a comprehensive assessment process of the task reliability of agricultural equipment was given, and the task reliability of agricultural equipment under multiple operational tasks was described quantitatively. Then, based on the correlation between the task reliability of agricultural equipment and the maintenance cost, an algorithmic model of the optimal maintenance inequality cycle and optimal maintenance times for each system, which met the constraints of minimum reliability and minimum maintenance cost, was established. Finally, an opportunity maintenance strategy was adopted to establish a maintenance optimization model for agricultural equipment. Taking the historical fault data and maintenance cost data of domestic wheel tractors as examples, the optimal maintenance schedule arrangement based on the optimal opportunity maintenance threshold was obtained. When the optimal maintenance threshold was 8h, the maintenance cost was 2.587 yuan. Compared with the traditional maintenance strategy of agricultural machinery equipment, the total maintenance cost was reduced by 30.4%. The proposed method was helpful to improve the task completion rate of agricultural machinery equipment, reduce the failure rate and maintenance loss of agricultural machinery equipment.

Abstract:During the operation of plant protection UAV, the vertical distribution law of the rotor wind field and the wind speed have a direct impact on the transport effect of droplets and the disturbing effect of the crop canopy. Taking the vertical distribution of the six-rotor UAV as an object, the simulation model of the rotor wind field using the numerical simulation technology based on the lattice Boltzmann method was established when UAV flying. In addition, according to the orthogonal test method, the influence of multi-feature parameter fusion on the vertical distribution of wind field and wind speed was studied. The simulation results showed that the vertical distribution wind field was symmetrically distributed perpendicular to the flight direction. When the flight height and flight speed increased or the operating load decreased, the wind field intensity was gradually weakened; the vertical distribution wind field was inclined along the crosswind direction, and when the crosswind wind speed was greater than 3m/s, the lateral inclination of the wind field exceeded 45°. Besides, a miniature wireless wind speed acquisition system was developed based on the constant temperature difference thermal chip, and a multi-factor field verification test of the vertical distribution characteristics of the wind field of the plant protection UAV was carried out. The results showed that the vertical distribution law of the rotor wind field between the simulation and the field test was basically the same, the relative error was small, and the vertical distribution of wind field had good consistency. The numerical simulation method can effectively simulate the unsteady flow during the flight process of plant protection UAV, and the simulation and field test results would provide a theoretical basis for the study of the droplet deposition of the plant protection UAV.

Abstract:In order to overcome the shortcomings of farms, such as high fecal water yield, small and scattered supporting arable land area, lack of small fecal water injection fertilization machine, low utilization rate of fecal water, a kind of equipment of self-propelled fecal water injection fertilizer applicator was developed. The capacity of the machine was 6m3, mainly composed of chassis, fertilizer tank, suction and discharge system and trenching fertilization syringe and other components. The complete machine structure and operational principle of the equipment were introduced. The research focused on the key components of the fertilizer applicator, such as tank structure, suction and discharge pipe system, control and monitoring system, fecal water divider and power extractor, which were designed and calculated. When the machine worked, it can realize the functions of fecal water multi-channel and multi-directional automatic suction and discharge, constant speed cruise, liquid circulating flow in the tank, furrow fertilization, injection cut-off and anti-blocking monitoring and alarm. According to the design requirements, the fertilizer applicator was trial produced, and the field experiment was carried out with pig farm manure as raw material. Experiment and test results showed that when the speed of the fertilizer applicator was 4km/h, the injection depth was 92.8mm, the stability coefficient of injection depth was 946%, and the consistency variation coefficient of fertilizer application was 5.3%. All indexes were consistent with the design value and met the agronomic requirements. The research result provided reference for the research and development of small self-propelled fecal water injection fertilization equipment.

Abstract:In agricultural production, it is challenging to detect the flow rate of fertilization due to the large amount and the mutual shielding of fertilizer particles. A granular fertilizer flow detection method based on the principle of luminous flux blocking was proposed to solve this problem. The feasibility of the detection method was preliminarily determined by theoretical analysis; discrete element simulation was used to analyze the distribution of granular fertilizer discharge in the conveying tube, which provided a basis for the structural design and installation position of the particle flow detection sensor (PFDS). Based on the above analysis, the PFDS and testbench were designed. Experiments were carried out by selecting urea and compound fertilizer as materials and the fertilizer discharging wheel (FDW) speed as factors to verify the method. The results showed a strong linear correlation between fertilizer flow and the cumulative response voltage of PFDS. Under different fertilization frequencies, the correlation determination coefficient (R2) of both was higher than 0.992. The detection models of each fertilizer frequency were established. Absolute percentage error (AE) and mean absolute percentage error (MAPE) were selected as the index. The MAPE of the detection model based on the “accelerate” for urea and compound fertilizer were 5.18% and 4.07%, respectively. And the detection error was lower than that of others, so the establishment method of the optimal detection model was determined. To solve the matching problem between the PFDS and fertilizer tube with different diameters, the experiments were carried out by taking the number of sensitive elements and the inner diameter of the PFDS as factors. The results showed that when the density of detection elements was 0.075~0.75, the MAPE range for urea and compound fertilizer were 4.75%~9.33% and 4.07%~9.11%, respectively, and the MAPE was decreased with the increase of detection element density. The detection method would provide technical support and solutions for granular fertilizer flow detection.

Abstract:In order to study the law of soil water and fertilizer transport under the corn full film double ridge planting mode in northwest arid area, the HYDRUS-2D/3D model was used to numerically simulate the law of soil water and fertilizer transport and root response of corn full film double ridge planting mode in Dingxi City, Gansu Province, the distribution law of soil water content and seed fertilizer concentration in the ridge under the full film double ridge planting mode was analyzed, and observation points at reasonable sowing depths were set to characterize the interaction law of soil water content, nitrogen phosphorus and migration of potassium, water and fertilizer. The simulation results showed that the circular lateral infiltration of soil water and fertilizer occurred at the infiltration holes and seed holes of full film double ridge and furrow, in which the fluctuation range of soil moisture content was 15.20%~17.12%, the concentration value of nitrogen fertilizer transformation in the ridge and furrow tended to be 15.38mg/L, the concentration value of phosphorus fertilizer transformation tended to be 5.15mg/L, and the concentration value of potassium fertilizer transformation tended to be 12.21mg/L. Water and fertilizer were mainly concentrated in the ridge and furrow, which ensured the water and fertilizer demand at the seedling stage. The simulation of root water uptake and water and fertilizer transport showed that the soil water and fertilizer conditions under the full film double ridge and ditch mode met the needs of maize seedling emergence. The research model and results would provide a theoretical basis for the optimization and improvement of maize full film double ridge and furrow agronomic technology.

Abstract:In order to meet the requirement of top dressing in the middle and late period of maize growth, a kind of pneumatic gathering and discharging type corn precision fertilizer mixing device was designed. The variable mixing fertilizer scheme with pneumatic set and row was designed. The motor driven blade rotation was used to mix fertilizer, and the inside of the fertilizer distributor was designed as a cone structure. By means of computer fluid dynamics, discrete element coupling method and two factors and five levels orthogonal experiment, the dip angle of the fertilizer outlet and the structure and arrangement of the bellows at the upper end of the distributor were studied. With the coefficient of variation of fertilizer discharge in each row as the test index, and with the angle of fertilizer discharge outlet, conveying gas velocity, and bellows length as the experiment factors, a three-way quadratic regression orthogonal combination design experiment was conducted to obtain the optimal operation parameters of key components of the precision fertilizer mixing device, namely, the angle of fertilizer discharge outlet of 45°, conveying gas velocity of 35m/s, and bellows length of 568mm. The inlet layout of fertilizer mixer was as follows: central layout, and the number of blades was 8. In June 2019, the machine field inspection was done at the National Agricultural Machinery and Tools Quality Supervision and Inspection Center, the inspection results showed that the machine's fertilizer application error was 2%, the total fertilizer application stability coefficient was 2%, and the fertilization rate was less than 2%. The research result can provide useful reference for the design and development of pneumatic fertilizing machinery and tools.

Abstract:A self-walking mulberry garden integrated machine with variable proportion and directional disperse fertilization was developed to balanced fertilization of nitrogen, phosphorus, potassium and organic fertilizers on demand and reduce non-point source pollution caused by unreasonable use of fertilization. The length, width and height of the integrated machine designed according to the planting row spacing of mulberry garden were 1450mm, 655mm and 1141mm, respectively, and the key components were designed. It was found that the standard deviation of the fertilizer application deviation was less than 0.4 when the roating speed of the flute-wheel was in the range of 20 ~ 80r/min. The distribution of the curved leaves was symmetrical and the fertilization effect was better. The orthogonal test was used to optimize the directional fertilization plate. The better combination of the directional fertilization plate was 450mm in length, 80mm in height and 100°in bending angle. Through response surface analysis, the influence order of the factors on the variation coefficient of fertilizer distribution was as follows: the speed of the fertilizer disperse plate, the distance between the receiving port of the collision blending device and the center of the fertilizer disperse plate, the working speed of the machine. The working parameters were optimized. The optimization results were that the speed of the fertilizer disperse plate was 290.1r/min, the distance between the receiving port of the collision blending device and the center of the fertilizer disperse plate was 88.2mm and the working speed of the machine was 0.5~0.7 m/s. It was verified that the variation coefficient of fertilizer distribution was less than 40% when the self-walking mulberry garden integrated machine working at the field experiment. The research result can provide a reference for the balanced fertilization of mulberry garden on demand.

Abstract:In order to study the influence of the core process of rapeseed pelletizing on the pellet quality, the contact mechanics of rapeseed pelletizing process were analyzed, a simulation model of the pelletizing process was constructed, validation tests were conducted and the rapeseed pelletizing process was optimized. The contact force analysis results led to the following conclusions: the tangential velocity was less than the threshold value, and no sliding friction occurred, which was the premise of bonding and coating. A larger normal contact force can increase the maximum static friction force, compact the pellet bonding, and promote the quality of pellets. Increasing the tangential contact force and reducing the normal contact force of pellets-pellets and powder-powder were beneficial to reduce the occurrence of problems such as multiple seeds, empty seeds, and deformation. The simulation analysis results showed 〖JP3〗that when the rotating speed was 1200r/min, the average speed of seed pellets and powder was 0.22m/s, creating static bonding conditions; the standard deviation of the speed distribution of seed pellets and powder was 0.42m/s and 0.52m/s; the average velocity of pellets-pellets, powder-powder, affected multiple seeds and empty seeds production. The powder supply speed affected the ratio of seeds to powder in the core bonding area. Too much powder formed empty seeds and wastes powder, and insufficient powder reduced the coating efficiency. The results of the orthogonal test showed that the powder-to-liquid ratio was the most important factor affecting the quality of pelletizing. The optimal parameters of the pelletizing rapeseed processing technology were obtained as follows: when the rotating speed was 1200r/min, the powder-to-liquid ratio was 2.1, and the powder supply speed was 24g/min, the qualified pellet rate was 95.7%, the single-seed rate was 94.9%, and the efficiency of pelletizing was 1.8kg/h. The research revealed the mechanism of seed pelletization and formed the process of rape seed pelletization, which was beneficial to promote the improvement of rapeseed seed processing level.

Abstract:Automatic head-tail and ventral-dorsal directional transportation is an important prerequisite for promoting the mechanized processing of freshwater fish. Based on horizontal vibration method and visual image recognition technology, an automatic head-tail and ventral-dorsal directional transportation device was designed. The principle of fish body rotation and the principle of head and tail advance were expounded by analyzing the force and motion state of fish body on the shaking table. The motion states of the fish on the shaking table were divided into four types, and the conditions for the fish to achieve head-tail directional transportation were analyzed. Combined with the image recognition technology, the guide mechanism, visual recognition system, elimination mechanism, V-shaped ventral-dorsal directional transportation actuator and V-shaped correction conveying mechanism were created to realize the automatic ventral-dorsal directional transportation. Finally, three typical freshwater fishes, crucian carp, Grasscarp and silver carp, were selected as the test objects, and the orientation completion time and success rate were used as the evaluation indexes. The effects of fish species, conveyor belt type, vibration amplitude and vibration frequency on the head-tail directional transportation of fish were explored, and the effects of fish species on the ventral-dorsal directional transportation were also explored. The test results showed that the theoretical calculation of the forward motion state of fish on the shaking table was consistent with the experimental results, it was proved that the theoretical calculation can effectively guide the actual head end orientation process. When the conveyor belt was only inverted triangle, the fish can complete the head-tail directional transportation. The effect of head-tail directional transportation was increased with the increase of vibration amplitude and frequency. When the vibration amplitude was greater than 160mm, the whole machine vibrated violently, so the optimal amplitude should be 160mm. When the frequency was greater than 5Hz, the change of orientation effect was not obvious, so the optimal frequency should be 5Hz. The ventral-dorsal directional transportation effect was determined by the conveying speed of the conveyor belt and the accuracy of machine vision recognition. The ventral-dorsal directional transportation time of all kinds of fish was kept at 15s, and the orientation success rate was stable in the range of 95%~97%. The research results can provide technical reference for the design and selection of technological parameters of fish automatic orientation device.

Abstract:For prawns in open back processes, and lack of practical equipment, taking Litopenaeus vannamei as research object, the key technology of prawn back opening was studied, the factors affecting the effect of back opening were analyzed, and the evaluation index requirements were established, in the rotating disc prawn open back device was carried on the three factors three levels of response surface optimization test, and the optimized drive back parameters were obtained. A validation test was carried out. In order to study the main influencing factors of open-back process of prawn, a mechanical model of open-back process of prawn was established. The main influencing factors were tool angle, machining center disk speed and tool placement distance. The optimal range of influencing factors was determined by single factor test as follows: tool angle of 20°~60°, machining center disk speed of 10~40r/min and tool placement distance of 9~11mm. Based on Box-Behnken central composite design theory, the three-factor and three-level response surface test was designed, and the test data were analyzed and optimized. The theoretical optimization results were as follows: under the conditions of 43.838° tool angle, 28.391r/min tool rotation speed and 9.801mm tool positioning distance, the success rate of back opening, shrimp damage rate, shrimp line naked success rate and sensory score were 99.161%, 2.825%, 90.727% and 86.944. Verification test results showed that for medium Litopenaeus vannamei, when the tool angle was 45°, the processing center rotation speed was 28r/min, and the tool placement distance was 9.8mm, the success rate of back opening was 98.89%, the damage rate of shrimp was 3.33%, the success rate of shrimp line exposure was 87.78%, and the sensory score was 85.33 points, and the absolute error between them and the theoretical optimization value was small. The reliability of the regression model prediction was proved, and the performance of the optimized prawns open-back device met the operation requirements.

Abstract:In order to solve the problems of insufficient resource utilization of kitchen waste, high pollution of waste treatment and high energy consumption and inconvenient operation of waste treatment equipment, an intelligent kitchen waste treatment equipment control system was designed to improve the automation level of kitchen waste treatment. The system was mainly composed of STM32 main control system, motor drive system, weight control system, temperature control system, auxiliary control system, purification system and storage system. The interface of intelligent serial port screen was designed based on USART HMI software. The intelligent serial port screen communicated with STM32 through TTL serial port, which could complete the working parameters setting of kitchen waste treatment and displayed the operation status information of the control system to realize the accurate control of kitchen waste treatment equipment. The experimental hardware platform was built, the temperature range of the system and the ratio of kitchen waste and high temperature aerobic microbial strains were used as experimental factors. The weight-loss ratio and power consumption of kitchen waste were used as experimental indexes. The experimental results showed that the temperature range of the system and the ratio of kitchen waste and high temperature aerobic microbial strains had very significant effect on kitchen waste treatment; when the temperature range of the control system was 85~95℃, the ratio of kitchen waste and high temperature aerobic microbial strains was 15∶1, 30kg kitchen waste and 2kg bacteria were treated for 5h, the weight-loss ratio was 90.38%, the average power consumption was 1.96kW·h, and the treatment effect of kitchen waste was remarkable. The system realized the harmless treatment of kitchen waste. The organic matter after kitchen waste treatment was converted into humus by aerobic composting technology, which was used for field fertilization or animal feed production to improve the utilization rate of waste resources.

Abstract:As a key component of the residual film barrier device, the air distribution chamber has the function of optimizing the flow field structure and uniform air curtain. Under the condition that the external structure of air distribution chamber is difficult to be further optimized due to the limitation of assembly space, the optimization of jet outlet structure parameters has a positive effect on improving the uniformity of air distribution in air distribution chamber. In order to improve the uniform stability of the jet curtain of the residual film barrier device, the velocity nonuniformity coefficient was used as the evaluation index, based on fluent, the range of influencing factors was determined by single factor experiment. Combined with second-order response surface method and non-dominated sorting genetic algorithm-II(NSGA-II), the optimal design parameters were obtained as follows: X1=70mm,Y1=2mm,X2=160mm,Y2=2mm, compared with the original device, the uneven coefficient of jet outlet velocity was reduced by about 28.6% and 25.9%, respectively. The experimental results showed that the maximum velocity deviation of two jet exits was 8.3% and 14% respectively, and the distribution trend of jet exit velocity was in good agreement with the simulation value.

Abstract:Taking a certain type of oblique flow pump as the research object, the computational fluid dynamics software CFX 2021R1 and the finite element analysis software ANSYS Workbench 2021R1 platform were used to solve the natural frequency and mode shape of the dry and wet mode of the oblique flow pump rotor system. The critical speed and the transient dynamics based on fluid-structure coupling, the deformation and stress distribution of the impeller blades at different positions were studied, and the influence of different flow conditions on the deformation and stress distribution of the impeller blades was compared and analyzed. The results showed that with an increase in the order, the natural frequency was gradually decreased. The 3rd order mode had the least decline rate at 9.82% while the 6th order mode had the highest decline rate at 44.31%. This confirmed the findings that the natural frequency of the rotor would decrease in the wet mode. The critical speed of the calculated second-order mode was 7369r/min, which was much greater than the rotor working speed. This indicated that the design requirements of the rotor dynamics met as the rotor system would not resonate when operating at working speed hence resulting in a stable operation. The deformation trends between the rear side of the blade and the working side of the impeller blade were quite similar. On the working surface, the deformation at the upper span of the blade towards the outlet was the largest. When the amplitude reached 2.6755mm, the deformation at each given position on the impeller blade working surface was higher than the rear surface with a maximum deformation of 0.0358mm. The deformation at the upper span of the blade was higher than at the root of the blade with the maximum difference being 1.0177mm. The highest amplitude reached 2.6755mm. Considering the stress change and stress amplitude trend, it was revealed that at the upper span of the blade near the inlet part were roughly similar on both sides. The stress amplitude graphs showed that towards the outlet portion of the blade, the upper span and root on the working surface had higher amplitudes than on the corresponding rear surface. The amplitude of the monitoring point at the outlet of the blade was significantly greater than that of the monitoring point at the inlet. On the rear surface, the equivalence force at the root of the blade towards blade was the largest, and the largest value reached about 6MPa. The change trend of blade deformation under different flow conditions was similar, and as the flow rate increased, the amount of deformation at each position of the impeller blade gradually decreased. At 0.6Q, the amount of blade deformation fluctuated the most with time. The maximum deformation was 3.0672mm, which appearred at the upper span of the impeller blade towards the outlet. At the upper span of the blade, as the flow rate increased, the stress fluctuation gradually decreased, at the blade root, the stress amplitude fluctuated the most at Q. The smallest fluctuations in inlet and outlet stress occurred under 0.6Q and 0.8Q flow conditions, respectively, and the maximum equivalent force was 12.456MPa. At the blade root, after each stress fluctuation, the 0.6Q and 0.8Q stress curve would have an additional small fluctuation, therefore operating the pump under small flow conditions must be avoided and also the blade thickness at the impeller root should be strengthened. The research results can provide a reference for the operation stability analysis of the oblique flow pump rotor system and the structural optimization design of the impeller blades.

Abstract:The cultivation density of cherry trees affects the light distribution of their canopies. By studying the three-dimensional structure of group cherry trees, the light distribution of greenhouse sweet cherry trees under different planting densities can be analyzed, which can guide the scientific planting of cherry trees and improve the yield and quality of sweet cherry trees. High quality point cloud data was the basis of constructing the three-dimensional structure of the group cherry tree, and point cloud denoising and registration were the key steps of point cloud data preprocessing. A method for denoising and registration of group cherry trees based on 3D point cloud was proposed to build a 3D information acquisition platform for group cherry trees, and two fixed DK depth cameras were used to obtain the color point cloud data of group cherry trees. A binary classification method based on color region growth was proposed, and the color threshold was set to segment the point cloud and perform binary classification processing, which can effectively remove the abnormal invalid points in the color point cloud data, and set the dispersion of point cloud and RGB value as the evaluation standard of point cloud denoising. Combined with manual labeling method and dual camera pose matrix, an improved ICP method based on color features was proposed to solve the problem that traditional ICP registration algorithm depended on the initial pose and the registration speed was slow. SIFT algorithm was used to extract the color feature points, and the color feature points were combined with ICP algorithm for precise registration. Then the random sampling consistency algorithm in PCL was used to remove the wrong matching points, which effectively reduced the registration time and improved the registration accuracy. Taking 20 groups of group cherry tree point cloud data in summer and winter as experimental objects, the registration accuracy and registration time of ICP algorithm, NDT algorithm, SAC-IA algorithm and the proposed registration method were compared and analyzed. The results showed that the average registration time of the proposed registration method was 5.01s and 4.30s, respectively. The root mean square error was 2.316cm and 2.100cm respectively, which effectively reduced the registration time and registration error, and verified the effectiveness and universality of the proposed algorithm.

Abstract:Aiming at the problems of low modeling accuracy, high cost and poor topology structure in the three-dimensional (3D) reconstruction of fruit trees, a 3D reconstruction method of fruit tree phenotype and skeleton extraction based on Kinect v2 sensor was proposed. Firstly, the Kinect v2 sensor was used to collect fruit tree point cloud data from different perspectives. Secondly, the characteristic point detection of scale invariant feature transformation was carried out on the plant point cloud, the eigenvector vector calculation was carried out by using the fast point feature histogram algorithm, the initial position of the point cloud was purified by the random sampling consistency method, and the improved iterative nearest point algorithm was used to finely register and stitch to form a complete point cloud after the initial transformation. Finally, the Delaunay triangulation of the point cloud data was used to fill the missing point cloud, the Dijkstra shortest path algorithm was used to obtain the minimum spanning tree, the skeleton was simplified by iteratively removing redundant components, the tree skeleton was estimated by the cylindrical fitting algorithm, and the tree skeleton was transformed into a closed convex polyhedron, and the 3D reconstruction of the branches of the fruit tree was realized. The experimental results showed that the average error of point cloud registration was 0.52cm, and the average error of branch reconstruction was not more than 3.52%, and the reconstruction effect was good. The research results can provide data support for orchard assessment of crop status, intelligent pruning and other research.

Abstract:Sea cucumber object detection is the premise of realizing automatic fishing of sea cucumber. To solve the problem of missed object detection caused by occlusion and the color similarity between object and background in the complex seabed environment, Swin RCNN object detection algorithm was proposed under the framework of Faster R-CNN. The backbone network of the algorithm adopted the Swin Transformer, and the multi-dimensional feature extraction layer was integrated into the structure, which improved the adaptive feature fusion ability of the algorithm and improved the object recognition ability of the model for the different sizes of objects under occlusion in complex environments. The actual experimental results showed that the mean average precision achieved 94.47% for the detection of sea cucumbers by the proposed approach, which was increased by 4.49 percentage points, 4.56 percentage points, 4.46 percentage points, 11.78 percentage points, and 22.07 percentage points compared with Faster R-CNN, SSD, YOLO v5, YOLO v4, and YOLO v3, respectively. The research result had certain reference significance for object detection in other complex environments. Therefore, the study of sea cucumber object detection algorithm in complex seabed environment had important theoretical and application value, and also had guiding significance for intelligent identification of other marine products.

Abstract:Waterin aquaculture is a necessary place for aquatic animals to survive and live. The deterioration of water quality will directly lead to the decline of aquaculture production, and in severe cases, it will lead to the death of a large number of aquatic organisms and cause serious economic losses to aquaculture enterprises.Therefore, the real-time monitoring of water quality parameters in aquaculture is of great significance.A method for water quality monitoring based on fish behavior was proposed with Oplegnathus punctatus as research object.The method can non-invasively complete the real-time monitoring of water quality parameters through the image data captured by the camera, avoiding the tedious installation of complex equipment and the quantification of fish behavior.To increase the inference speed and reduce the amount of model parameters, this method combined RepVGG block with GhostNet.Aiming at the problems of rapid water quality monitoring and accurate water quality monitoring, the Cheap Ghost operation and the Expensive Ghost operation were proposed.Finally, the three branches were merged through model reparameterization, which greatly reduced the amount of model parameters and improved the model inference speed.The results showed that the G-RepVGG operated by Cheap Ghost achieved an accuracy of 96.21% in the test set and can infer 442.27 images per second. The G-RepVGG model operated with Expensive Ghost achieved 97.63% accuracy in the test set and can infer 349.42 images per second. Therefore, it still had a high inference speed under the premise of ensuring high accuracy, and had better robustness in testing in multiple data sets. The research result can quickly and accurately monitor water quality, detect water quality deterioration in time, and reduce losses caused by water quality deterioration, providing ideas and methods for water quality monitoring.

Abstract:Feeding as a key part of the aquaculture process, the amount of bait fed directly affects the quality of aquatic products and the cost of aquaculture. However, the current feeding methods include manual feeding and machine feeding at regular intervals, which mostly rely on manual experience and are difficult to achieve accurate feeding. Different satiation levels of fish were identified based on the improved ResNet34, which was important for achieving accurate control of bait feeding in the future. A dataset- containing five different satiation levels was created based on the feeding behaviors exhibited by fish at different satiation stages, and the images were pre-processed using data enhancement operations. Secondly, based on the original model ResNet34, the use of coordinate attention mechanism wasproposed to enable the model to focus on a large area in the process of feature extraction of images. And the depth-separable convolution was used instead of the traditional convolution to reduce the number of model parameters. To evaluate the effectiveness of the improvements, the performance of the improved model wasanalyzed on the fish satiation dataset and compared it with the original model ResNet34, AlexNet,VGG16, MobileNet-v2, GoogLeNet and other classical convolutional neural network architectures. The comprehensive experimental results showed that the model reduced the amount of parameters by 46.7% and achieved an accuracy of 93.4% compared with the original model, which had a 3.4 percentage points improvement compared with the original model, and the improved model also outperformed other convolutional neural networks in terms of accuracy, precision, recall, and F1 score. In summary, the model achieved a good balance between performance and number of participants, which provided the possibility for subsequent models to be deployed in real farming environments and guide farmers in improving and developing feeding strategies.

Abstract:In order to improve the efficiency and accuracy of cows body size measurement and reduce labor intensity, a cows body size measurement method based on key frame extraction and head and neck removal was proposed. Firstly, a cows top-down depth video acquisition platform was built, and the cows target in the depth image was extracted by using the watershed algorithm. Secondly, the contours of the left and right sides of the cows were obtained by using the image scanning strategy, and the key frames containing the complete cows torso in the image sequence were extracted by using the Hough transform-based line detection method. Then, according to the skeleton features of the cows-head area, itwas determined whether the head existed. If the head existed, the cows-head in the image was removed based on the convex hull analysis method, and the cows-neck was removed by the polynomial curve fitting method. Finally, according to the spatial characteristics of the cows-body measurement points, the straight length, shoulder width, belly width, hip width and body height of the cows were automatically calculated. The accuracy of the method was tested with 2.163 depth images of 35 cows. The analysis result showed that the accuracy of the key frame extraction method was 97.36%, which can effectively replace the manual selection of key frames. The accuracy rate of the head detection method was 94.04%, which improved the efficiency of the cows body measurement point positioning. The average relative error of body measurements was within 3.3%. The research results can effectively improve the efficiency and accuracy of automatic measurement of cows body size.

Abstract:The dynamic weighing signal of dairy cows contains many signals in different frequency domains, including the weight signal of dairy cows, the inertial component signal and various noise signals. In the previous studies, the information utilization rate of dynamic weighing signal was low, and the deep information of weighing signal could not be fully extracted. To solve this problem, a method based on variational mode decomposition（VMD）and long short-term memory network (LSTM) dynamic weighing algorithm was proposed to improve the accuracy of weight prediction. Firstly, the threshold filtering method was used to obtain the effective signal from the collected dairy cow dynamic weighing signal. Secondly, in order to extract the deep information contained in the dynamic weighing signal of dairy cows, the VMD algorithm was used to decompose the pre-processed effective signal into five intrinsic mode functions (IMF). Finally, each IMF component was combined with the effective signal as feature, which was input into the LSTM neural network as features for training, and then the weight of cows was output. The prediction results of models with different characteristics were compared, as a result, the model with the minimum error was selected as the cow body weight prediction model. The experimental results showed that the proposed dynamic weighing algorithm can effectively extract the deep information contained in the dynamic weighing signal of dairy cows. The average relative error of weight prediction was 0.81%, and the root mean square error was 6.21kg. Compared with EMD algorithm and GRU algorithm commonly used in the field of dynamic weighing, the error of the proposed algorithm was smaller.

Abstract:With the improvement of the requirements for intensive breeding of calves in large-scale pastures in China, in terms of nutrition, immunity and management efficiency, a feeding information system was designed to realize the visual management of data in the whole feeding process of calves of different ages，aiming to adapt to the needs of the reform of the working mode of breeding managers. Improved Logistic regression algorithm was used to predict the milk supply of calves to realize automatic and accurate feeding, and ensure the healthy development of calves. Based on the B/S architecture, a calf feeding information management system was designed, which can collect the basic information of calves, calf weight, historical milk drinking information of calves, real-time milk drinking information of calves, and working status of milk drinking stations, and all kinds of data of the elements, realizing the front-end display and back-end storage of the data, and visualization of the data in the whole process of calf feeding. Based on the Logistic regression algorithm, a prediction model for the milk supply and milk replacer concentration of calves was established，the running time of the improved algorithm can be shortened to 0.3s, and the efficiency of the algorithm can be increased by 12 times. The calf breeding test showed that the prediction model had good accuracy. The average actual milk drinking rate of calves in the experiment reached more than 95%. The intelligent and refined level of cattle management reduced feeding costs.

Abstract:The ammonia nitrogen concentration in vinasse slurry is high, and the use of ammonia stripping technology to recover nitrogen nutrients has problems such as low utilization rate of alkali agent, poor gas-liquid contact effect and low ammonia absorption effect. In order to improve the ammonia recovery efficiency and process economy of vinasse slurry, the conditions of the vinasse slurry ammonia stripping process were optimized, and the effects of different temperatures, Ca(OH)2 dosage and filler types on ammonia stripping and acid absorption were explored. The influence of the operation effect of the integrated test device was evaluated, and the economical evaluation of the ammonia stripping process from the vinasse slurry was carried out. The results showed that the order of importance of influencing factors was obtained by orthogonal test was alkali dosage, air flow and temperature. The optimal process parameter combination was Ca(OH)2 dosage of 6.6g/L, gas flow of 6L/min and at a temperature of 52℃, the corresponding ammonia nitrogen removal rate was 99.0%; Ca(OH)2 had a good removal effect on SCOD and TP, and the corresponding SCOD and TP removal rates were 32.5% and 65.7% under the condition of 6.6g/L alkali dosage. The addition of Ca(OH)2 compared with the plan without alkali significantly improved the removal rates of ammonia nitrogen, TN, EC, SCOD and TP in the stripping process, reaching 97.4%~97.7%, 79.8%~84.2%, 68.3%~77.4%, 36.8%~45.3% and 77.1%~91.0%, respectively. The suitable anmonia stripping parameters are hacketten filler 37℃ and twice adding Ca(OH)2. The ammonia nitrogen removal rate reaches 97.4%, the effluent ammonia nitrogen concentration is as low as about 100mg/L, and the ammonia recovery amount reaches 1.22kg/m3. Compared with the scenario of no alkali addition and one-time alkali addition, the ammonia nitrogen removal rate can exceed 97% in the two-time alkali addition process scenario. The effluent ammonia nitrogen concentration was low (about 100mg/L), and the treatment cost was 9.75 yuan/m3, which had a relatively good economy. Therefore, ammonia stripping had good suitability for the treatment of scenario with high ammonia nitrogen concentration. The efficient recovery of nitrogen nutrients through ammonia stripping can relieve the pressure of biogas slurry farmland utilization, which was of great significance for the resource utilization of biogas slurry.

Abstract:For the treatment and prevention of animal diseases, antibiotics are commonly used in livestock and poultry farming. The large amount of antibiotics remaining in livestock and poultry manure brings a huge potential risk of the spread of antibiotic resistance genes. In order to further understand the degradation characteristics of typical antibiotics in livestock and poultry manure by hydrothermal pretreatment and anaerobic digestion, and clarify the correlation between antibiotics and methane production performance, pig manure was taken as the research object. The reduction effects of different temperatures (70℃, 90℃, 120℃, 150℃ and 170℃) by hydrothermal pretreatment on sulfadiazine, oxytetracycline and enrofloxacin were investigated. The degradation laws of sulfadiazine, oxytetracycline and enrofloxacin during mesophilic anaerobic digestion and their effects on methane production performance were studied. The results showed that the hydrothermal pretreatment had obvious reduction effect on the three antibiotics. Sulfadiazine and enrofloxacin were 100% removed by hydrothermal treatment at 70℃, while oxytetracycline was 100% removed by hydrothermal treatment at 90℃. During mesophilic anaerobic digestion, the removal rates of the three antibiotics were increased gradually with the prolongation of anaerobic digestion time. After 5d of anaerobic digestion, enrofloxacin basically reached 100% removal, while the removal rates of oxytetracycline and sulfadiazine were 39.76% and 21.29%, respectively. After 15d of anaerobic digestion, oxytetracycline basically reached 100% removal, while after 30d of sulfadiazine, the removal rate reached 52.9%. The degradation characteristics of the three antibiotics were quite different in the process of anaerobic digestion, but there was no significant difference in the biogas and methane production of pig manure with different antibiotics (P>0.05). In addition, when the sulfadiazine in pig manure was in the range of 5~150mg/kg, cumulative biogas and methane production from anaerobic digestion was negatively linearly correlated with sulfadiazine concentration (R2=0.9546 and R2=0.8654). However, there was no significant difference in biogas and methane production with different antibiotics (P>0.05). Therefore, hydrothermal pretreatment and anaerobic digestion can significantly reduce sulfadiazine, oxytetracycline, and enrofloxacin in pig manure, which can provide data support for the subsequent study of hydrothermal pretreatment combined with anaerobic digestion in the treatment of antibiotic-containing manure.

Abstract:In order to solve the problems of large-scale pig house, such as high labor intensity, repeated operations and severe epidemic situation, a pig house disinfection and sterilization inspection and environmental monitoring systemwas designed.The system integrated the 2D LiDAR based simultaneous localization and mapping (SLAM) and ultra wide band (UWB) technologies to realize the building of in-house map and real-time positioning of the system. On the basis of determining the installation height of the thermal infrared module to be 125cm and the horizontal downward angle of the installation inclination to be 5°, the Jetson Xavier NX edge computing unit was used to deploy vision processing and recognition algorithms to conduct online inspections of pig body temperature. The edge computing unit was used to intelligently control the atomization module and the ultraviolet module in the disinfection module according to the terminal instructions and the information of the micro-environment in the house, so as to realize the multi-mode disinfection of the indoor environment. The sensor technology was used to monitor the environmental parameters in the house in real time. Human-computer interaction interface was built to realize the display, alarm and storage of monitoring information. The test results showed that the system can complete map construction, automatic navigation, pig body temperature detection, and record abnormal pig thermal infrared pictures and the location of the enclosure. According to the set disinfection and sterilization mode, the accuracy of completing the corresponding disinfection and sterilization function at the target point was 100%. The relative errors of CO2 concentration, temperature and humidity in the room were 0.04%, 3.00% and 2.10% respectively in the inspection state and static state of the robot. The research result can provide technical equipment reference for the less-humanized/unmanned operation of inspection and disinfection of pig houses during the epidemic situation.

Abstract:Ractopamine is a synthetic βreceptor agonist that can be used to feed livestock to improve lean meat yield. Ractopamine can cause health problems and even endanger life if eaten from livestock, poultry or viscera. Traditional ractopamine detection cycle is long, time-consuming and laborious, which is not conducive to the actual large-scale promotion of use. In some slaughterhouses, sampling inspection is often used for testing which is a serious lag. A portable rapid screening device for ractopamine in pork was developed. The device mainly included spectra acquisition module, light source module, control module, power supply and computer. Based on NI LabVIEW software development tool, G language was used to write the control software of intelligent and rapid detection of pork “clenbuterol”. Firstly, ractopamine was extracted from pork by ethyl acetate in alkaline environment, and detected by SERS method. The effects of several different concentrations of NaCl aqueous solutions as aggregators on SERS spectra of ractopamine were compared. The results showed that 1mol/L NaCl as aggregator had the best enhancement effect. Secondly, the effect of droplet evaporation on Raman signal was compared. The results showed that the Raman signal was better after 4s. Then, pork samples with different ractopamine contents (1μg/g, 2μg/g, 4μg/g, 6μg/g, 8μg/g and 10μg/g) were prepared for quantitative analysis. Automatic Whittaker fitting algorithm (AWF) was used for preprocessing, and the fluorescence background contained in the original Raman spectrum was deducted. A linear regression model was established between SERS intensity at 836cm-1 and ractopamine content in pork samples. The results showed that the model has a good linear relationship, the correlation coefficient R2 was 0.99, and the root mean square error was 0.178μg/g. Finally, a batch of pork samples with the same ractopamine content were prepared, and the device was used to detect ractopamine in pork. The predicted values had a good linear relationship with the standard physicochemical values of the samples, the correlation coefficient R2 was 0.99, and the root mean square error was 0.317μg/g. The device was simple, portable, inexpensive, and the detection time was less than 1h. The detection limit was 1μg/g. It can be used for rapid screening of ractopamine in pork.

Abstract:Aiming to improve the drying uniformity of corn ear and drying efficiency, reduce the quality loss, and optimize the design of drying and storage equipment for corn ear, a deep bed drying test equipment of corn ear was designed according to the drying technical requirements. The drying test equipment included hot air device, drying section, control system, temperature and humidity monitoring components. The corn ear drying characteristics and quality experiment were conducted at different wind speeds (0.5m/s and 1m/s), hot air temperature (room temperature, 50℃, 60℃ and 70℃) and material layer thickness (180mm, 360mm, 540mm and 720mm). The result showed that with the increasing of hot air temperature and wind speed, the drying rate was improved. When the wind speed was 0.5m/s, the drying time of the first material layer under the hot air temperature of 50℃, 60℃ and 70℃ was 28h, 20h and 14h, respectively. However, the moisture content (wet basis) of corn ear at room temperature drying only dropped to 20% after 192h. With the decrease of the hot air temperature, the drying time was significantly prolonged. Increasing hot air speed was beneficial forimproving the drying rate. The change of the drying rate of corn ears in the third and fourth material layersinfluenced by hot air speed was greater than that of the first or second layers. When the hot air temperature was 50℃, the drying time at the first material layer under the wind speed of 1m/s was 14.3% lower than the wind speed of 0.5m/s. With the increase of material layers, the drying rate under each drying condition was significantly reduced, and the drying time was prolonged. The material layer of corn ear at room temperature drying conditions was in a high-humidity environment for a long time. Drying corn ear in the stage of high water content by the natural ventilation method was easy to cause internal high humidity and high temperature. The moisture content of the corn kernel was decreased firstly during the drying process，and the moisture content of the corn cob was much higher than that of the corn kernel. Compared with the control group, the brightness value of the dried materials was decreased. Besides, the increasing of the hot air speed and temperature would decrease the brightness value of corn kernel. The electrical conductivity of corn kernels dried at room temperature was the lowest, which was 104μS/cm. With the increase of hot air temperature and wind speed, the electrical conductivity was increased, indicating that the internal structure of maize kernels was damaged greatly. The starch content and soluble sugar content of corn kernel were decreased after drying, among which the starch content was the lowest at 70℃, 0.5m/s and the soluble sugar content was the lowest at 60℃ and 70℃, 0.5m/s. On the basis of the drying characteristics and quality changes of corn ear, it was determined that the deep bed drying process of the corn ear was the method of hot air drying first and then drying at room temperature. The optimal hot air drying process parameters of corn ear was hot air temperature of 50℃ or 60℃, wind speed of 0.5m/s and air channel’s unilateral material layer thickness of 360mm.

Abstract:Drying model for grains is still often adopted in most current numerical simulation for fruits and vegetables during drying, leading to low simulation accuracy, for the shrinkage effect was not considered in physical model and heat and mass transfer. In order to calculate the shrinkage model during hot-air drying and simulate the distribution of internal temperature and humidity field with and without shrinkage, white radish with uniform structure and visible shrinkage during drying was chosen as a representative material. The results of the drying experiment demonstrated that the sample length had a significant impact on the characteristics of shrinkage, and the isotropic rate of drying shrinkage was the best at a sample length-to-radius ratio of 10, at which point the Hatamipour model was most appropriate to explain the shrinkage law of white radish by hot-air drying. And then, the heat mass transfer of white radish during hot-air drying was investigated based on the coupled shrinkage equation and heat and mass transfer equations by moving mesh method. The numerical simulation results showed that the migration path of moisture inside the material became shorter after shrinkage, and the faster removal rate led to a significant reduction of both internal and external moisture content at each time point, as well as a reduction in the moisture gradient at the superficial layer of material. Compared with the model not considering shrinkage, the moisture evaporation in the early and middle stages of drying was larger, while the moisture content in the later stage was smaller, so that more heat would be consumed for moisture evaporation in the early and middle stages and the latent heat dissipation for evaporation in the later stage was reduced. The above phenomenon led to a rapid rise in material temperature to 30℃ and then slowly raised to an equilibrium temperature of 60℃, which was closer to the experimental value. Specifically, the deviations of simulation results for internal and external moisture and temperature of the material after combining the shrinkage equations were reduced from 17%~8% and 12~2℃ to 14%~3% and 3~2℃, respectively. Therefore, the numerical simulations based on moving mesh can effectively interpret the effect of shrinkage on the physical model of materials and the heat and mass transfer law, thus providing a higher computational accuracy and a reliable model for the analysis of the heat mass transfer during hot air drying.

Abstract:Due to the shortcomings of ergonomics and comfort in the design of tractor cabs, the mathematical model of each joint of the human body was established by theoretical calculation. The model was based on a definition of the angle and length of each joint of the human body in GB/T 21935—2008 standard, and the recommendation of GB/T 6235—2004 on the seat marking points position. Based on the simulation analysis of human manipulation based on RAMSIS software, a three-dimensional model of human manipulation comfort zone on both sides of the driver's seat was constructed based on the optimized range of human manipulation comfort zone and accessibility zone specified in GB/T 21935—2008 standard. Combined with RAMSIS software, the existing tractor cab internal control components were optimized. The included angle between the foot accelerator pedal surface and the floor surface was adjusted from 45°to 35°. The overall position of the foot accelerator was shifted outward by 25mm, and the width of the brake pedal surface was reduced by 40mm. At the same time, the structure at the 265mm distance from the ground of the main gear lever was adjusted outward by 20mm, and the initial position of the hand brake was raised by 45mm. Experiments were carried out on the optimized prototype, and the control force and stroke of each component were measured to verify the correctness of the proposed three-dimensional model of the human operation comfort zone. During the present study, a mathematical model of the comfort zone and the arrangement position of the control components was provided for the ergonomic design of the tractor cab. The research result could provide a reference for the tractor cab design. Also, it would expand the application of ergonomics in the field of tractor design and improve the driving comfort of tractors.

Abstract:In order to realize the lightweight of the high-horsepower tractor gear box under the requirements of strength and stiffness, a multi-objective optimization method for high-horsepower tractor gear box based on an improved non-dominated sorting genetic algorithm-Ⅱ (NSGA-Ⅱ) was proposed. Firstly, the force of the gear box was analyzed, and the statics simulation analysis method of the load-bearing gear box was proposed. The strength and stiffness performance of the gear box were simulated and analyzed by ANSYS. Then, K-means clustering algorithm, normal distribution crossover (NDX) and differential mutation search strategy were introduced to improve the NSGA-Ⅱ algorithm, and example tests were carried out. The results showed that the solution set distribution uniformity and stability of the improved NSGA-Ⅱ were better than NSGA-Ⅱ, and the optimization effect was better, which verified the effectiveness and superiority of the proposed algorithm. Finally, the multi-objective optimization of the gear box was carried out based on the improved NSGA-Ⅱ algorithm, and the simulation analysis and verification of the optimized gear box were carried out. The results showed that the mass, maximum deformation and maximum stress of the optimized gear box were 168.16kg, 0.449mm, and 215MPa, respectively, which were better than 168.16kg, 0.454mm, and 216.12MPa of NSGA-Ⅱ. That realized the lightweight of the high-horsepower tractor gear box under the requirements of strength and stiffness, and further verified the effectiveness and superiority of the proposed algorithm in solving the multi-objective optimization problem of high-horsepower tractor gear box, and the research results provided a method reference for the simulation and optimization of the high-horsepower tractor gear box.

Abstract:An active rollover stabilization control system was designed based on a single-frame control moment gyroscope for tractors susceptible to limit state rollover instability caused by complex road conditions in slope driving. The Euler-Lagrange equations were used to construct the non-linear sway dynamics equations for the coupled system of the whole machine and the control moment gyro using the single-side tire off the ground as the main object of study. Considering the different degrees of rollover hazards under random road conditions, a state feedback control law was derived based on the backstepping design method. To ensure the smooth control process, the control law was used to adjust angular speed and angular position of the gyroscope rotor. Through the precise movement of the gyroscope rotor, the active rollover control moment of agricultural wheeled tractor was output to change the rollover trend. Finally, scaled model tests of limit state rollover instability control with different obstacles and speeds were also carried out. The results showed that compared with the uncontrolled group, the use of the moment gyroscope control system can significantly reduce the ultimate roll angle of the tractor and can still effectively control the rollback when the roll angle was greater than the static critical roll angle of 9.58%. The proposed control strategy can adapt to the ultimate rollover conditions of different levels of risk and broaden the range of safe driving slope of the tractor. The active rollover control system can provide a theoretical basis and technical support for improving tractor slope adaptability.

Abstract:Aiming at the difficulties in the field test and poor repeatability of the electro-hydraulic hitch control system for hilly and mountainous tractors, the research on the electro-hydraulic hitch control system was carried out based on the semi-physical simulation technology. Firstly, through the force analysis of the test tractor and the suspension operation device, the dynamic model of the whole hilly and mountainous tractor, the soil resistance model of the plough body and the dynamic model of the tractor suspension device were established. The system principles of lateral profiling control, position control, force control and force-position integrated control of the electro-hydraulic suspension system for hilly and mountainous tractors were analyzed, and then a fuzzy PID controller for the electro-hydraulic suspension of hilly and mountainous tractors was designed. Afterwards the electro-hydraulic suspension control system was developed, experiments such as terrain imitation control, force control, position control and force-position integrated control of electro-hydraulic suspension system were carried out, and the performances of fuzzy PID control and classical PID control method were compared and analyzed. Finally, the test results showed that the fuzzy PID control performance was better: in the position control mode, the fuzzy PID control had no overshoot, and the control system response time was 0.6s, which was about 33.3% higher than the classical PID control; the steady-state error of the tillage control system was about 0.05cm, which was about 50% lower than that of the classical PID control; in the force control mode, the maximum value of the tillage depth following error of the fuzzy PID control was 0.38cm, and the standard deviation was 0.17cm, which were respectively 64.5% and 39.3% lower than that of the classical PID control, which verified the effectiveness of the developed electro-hydraulic suspension control system.

Abstract:In order to improve the operation stability of mountain tractors in complex farmland environment, based on the Matlab/Simulink simulation platform, a time-domain simulation model of a semi-active suspension tractor with D-level road roughness as the road excitation was established and which had seven degrees of freedom. The simulation time domain model included four-wheel road excitation model, semi-active suspension vibration model, semi-active suspension vibration model, semi-active suspension tractor time domain simulation model, the vertical displacement of body, body inclination angle and body pitch angle were used as the attitude change parameters of the tractor to carry out the simulation test. By constructing the incremental proportion integration differentiation,（PID）controller and the back propagation（BP）neural network PID controller simulation model, the automatic control of the body attitude of the semi-active suspension tractor was realized, and the control performances of the two controllers were respectively evaluated. Using the vertical acceleration of the body and the relative dynamic load of the wheels as the performance evaluation indexes of the semi-active suspension system, the performance of the semi-active suspension under the two control modes was evaluated. The simulation results showed that for the semi-active suspension tractor based on the traditional incremental PID control algorithm, the RMS value of the body vertical displacement was reduced by 42.17%, the root mean square value of the roll angle was reduced by 36.76%, and the root mean square value of the pitch angle was reduced by 57.85%. The vertical acceleration of the vehicle body was 0.0177m/s2, and the RMS values of dynamic load of the four wheels were 0.0284N, 0.0346N, 0.0239N, and 0.0304N, respectively. The semi-active suspension tractor based on the BP neural network PID control algorithm reduced the RMS value of the body vertical displacement by 74.54%, the root means square value of the roll angle by 74.66%, and the root mean square value of the pitch angle by 75.03%. The vertical acceleration of the body was 7.5758×10-5m/s2, and the RMS values of dynamic load of the four wheels were 0.0197N, 0.0235N, 0.0166N and 0.0198N, respectively. Compared with the semi-active suspension tractor controlled by incremental PID, the body stability of the semi-active suspension tractor based on BP neural PID control was better improved, which provided a theoretical basis for the design of the mountain tractor control system.