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Cotton stalk is an important renewable resource. China is rich in cotton stalk, if such a large amount of resources are recycled, it will produce huge economic benefits. But most of them are not recycled at present. In order to improve the mechanized recovery level of cotton stalk, study the influence of different parameters on the mechanized recovery of cotton stalk, and solve the outstanding problems such as high cotton stalk plucking rate and high cotton stalk leakage rate, this paper studied and designed a toothed disc cotton stalk harvester. The machine was consisted of suspension device, limit wheel, pull-out tooth plate, stalk discharge device, hydraulic motor, hydraulic pipeline and hydraulic control box. The key component of the machine was a toothed disc type stalk pulling device. During operation, the cotton stalk was lifted out through the toothed disc, and then the cotton stalk was discharged to the surface through the stalk discharge device. Leakage rate and plucking rate of cotton stalk were the main parameters to evaluate the performance of toothed disc cotton stalk harvester. In this paper, Box-benhnken central combination test method was used to study the working parameters of toothed disc cotton stalk harvester. Three-factor and three-level quadratic regression orthogonal test was designed. The three-dimensional model of response surface was established with the diameter of the toothed disc, the toothed disc speed ratio and the lifting height as the influencing factors. The influence of each factor on the quality of work was analyzed, and the influencing factors were optimized synthetically. The results showed that the lifting height and the toothed disc speed ratio had significant effects on the cotton stalk plucking rate (P< 0.01), while the lifting height, the diameter of the toothed disc and the toothed disc speed ratio had significant effects on the rate of cotton stalk leakage rate (P<0.01). The working parameters of the machine were deduced from the regression model optimization as follows: the lifting height was 66.2 mm, the diameter of the toothed disc was 627.59 mm, and the toothed disc speed ratio was 0.57. In November 2018, field test was carried out in the Yellow River Delta (Binzhou) National Agricultural Science and Technology Park. Test area was divided into 17 test plots, leakage rate and plucking rate of cotton stalk at each test plot were calculated. The results of the Daejeon experiment showed that when the lifting height was 70 mm, diameter of the toothed disc was 630 mm and the toothed disc speed ratio was 0.57, the cotton stalk plucking rate could reach 1.5% and the cotton stalk leakage rate was low to 3.0%. The test results showed that the theoretical results were coincident with the measuring results, and the error between them was less than 4%. The research results can provide references for the structure improvement design and operation parameters optimization of toothed disc cotton stalk harvester. [ABSTRACT FROM AUTHOR]

In most areas of Xinjiang, edible sunflower is harvested in stages by means of transplanting plates for drying and taking plates for threshing. In some areas, edible sunflower harvesters are used for field operations, and problems such as edible sunflower plate leakage and grain loss exist in the process of harvest, which seriously hinder the development of edible sunflower scale and industrialization. In order to solve these problems and improve the harvesting efficiency of edible sunflower machine, this paper conducted a field survey on planting mode and biological characteristics of the edible sunflower in Xinjiang, and summarized the harvesting mechanism of edible sunflower. Starting from the operation path of manual harvesting sunflower tray, and combining with the requirements of field harvesting, a kind of collecting station for edible sunflower was designed. Field experiment was carried out to verify the field performance of the collecting station for edible sunflower. The specific research contents and conclusions were as follows. First of all, experimental study on the physical characteristics of edible sunflower was made during harvest in Xinjiang. It mainly included the determination test of the basic physical quantity, the friction characteristic test and the impact seed falling test. The average moisture content of edible sunflower plate was 38.97% and that of culm was 65.49%. By the bevel method, we got the friction angle between the dish and the steel plate was about 29.2°, the static friction coefficient was 0.56. The experiments were carried out to obtain the operating parameters with less loss of sunflower plate, which provided the theoretical basis for the field operation of edible sunflower harvesting platform. Secondly, in this paper, the whole plan of the collecting station for edible sunflower was determined, and the structural design and parameter analysis of the key devices were carried out. This paper designed a kind of station for collecting edible sunflower by imitating the manual way of picking dish. The whole machine structure was mainly composed of the pick-up device, conveying device, collecting dish box, walking device, power transmission system and frame. By analyzing the segmented path map of manual picking-up and parabolic dish, and combining the working posture of the pick-up device in each harvesting stage, the bionic pick-up device was designed and the basic structural parameters were determined to achieve the goal of bionic dish taking action and the shortest parabolic dish path. The 3D model of the pick-up device was established and the kinematics analysis were carried out to obtain the displacement, speed and acceleration change rules of the pickup device's disk-bar and determined the best structure and working parameters combination of the pickup device. The conveying device was designed and the speed of it was calculated to be 92 r/min, the theoretical productivity was 2.19 t/h. By analyzing the power transmission system, we got the transmission law of chain. The field harvest test finally was carried out with the total harvest loss rate as the test index, the height of the plug plate, the rotational speed of the take-up rod and the forward speed of the unit as the test factors. The results showed that the collecting station for edible sunflower could complete the functions of picking up, transporting and collecting. The optimal combination of the collecting station for edible sunflower was that the height of the disc was 650 mm, the forward speed of the unit was 0.88 m/s, the rotational speed of the take-up rod was 23 r/min, and the total loss rate of harvest was less than 5%, which could meet the operation requirements of Xinjiang edible sunflower harvesting. [ABSTRACT FROM AUTHOR]

Cotton stalk is an important renewable resource. China is rich in cotton stalk, if such a large amount of resources are recycled, it will produce huge economic benefits. But most of them are not recycled at present. In order to improve the mechanized recovery level of cotton stalk, study the influence of different parameters on the mechanized recovery of cotton stalk, and solve the outstanding problems such as high cotton stalk plucking rate and high cotton stalk leakage rate, this paper studied and designed a toothed disc cotton stalk harvester. The machine was consisted of suspension device, limit wheel, pull-out tooth plate, stalk discharge device, hydraulic motor, hydraulic pipeline and hydraulic control box. The key component of the machine was a toothed disc type stalk pulling device. During operation, the cotton stalk was lifted out through the toothed disc, and then the cotton stalk was discharged to the surface through the stalk discharge device. Leakage rate and plucking rate of cotton stalk were the main parameters to evaluate the performance of toothed disc cotton stalk harvester. In this paper, Box-benhnken central combination test method was used to study the working parameters of toothed disc cotton stalk harvester. Three-factor and three-level quadratic regression orthogonal test was designed. The three-dimensional model of response surface was established with the diameter of the toothed disc, the toothed disc speed ratio and the lifting height as the influencing factors. The influence of each factor on the quality of work was analyzed, and the influencing factors were optimized synthetically. The results showed that the lifting height and the toothed disc speed ratio had significant effects on the cotton stalk plucking rate (P< 0.01), while the lifting height, the diameter of the toothed disc and the toothed disc speed ratio had significant effects on the rate of cotton stalk leakage rate (P<0.01). The working parameters of the machine were deduced from the regression model optimization as follows: the lifting height was 66.2 mm, the diameter of the toothed disc was 627.59 mm, and the toothed disc speed ratio was 0.57. In November 2018, field test was carried out in the Yellow River Delta (Binzhou) National Agricultural Science and Technology Park. Test area was divided into 17 test plots (each plots is 30 m×0.76 m), leakage rate and plucking rate of cotton stalk at each test plot were calculated. The results of the Daejeon experiment showed that when the lifting height was 70 mm, diameter of the toothed disc was 630 mm and the toothed disc speed ratio was 0.57, the cotton stalk plucking rate could reach 1.5% and the cotton stalk leakage rate was low to 3.0%. The test results showed that the theoretical results were coincident with the measuring results, and the error between them was less than 4%. The research results can provide references for the structure improvement design and operation parameters optimization of toothed disc cotton stalk harvester. [ABSTRACT FROM AUTHOR]

Grain loss rate is one of the most important performance index of corn head in mechanized harvesting. Seed harvesting is the main development direction of mechanized corn harvesting. The characters of seed harvesting corn variaty increased the urgency to reduce grain loss on corn head. The paper was proposed to solve the problem of grain loss on corn head. Theoretical analysis was conducted to the snapping process. Corn ear was subjected to pull force by the snapping rolls and the pull force transferred by corn stalk. Corn kernels were divided into 2 types due to their force condition. A kernel at the bottom end of corn ear was subjected to reaction forces by stripper plates, corn cob and the adjacent kernels and shear force by the pedicel. Kernels out of contact with the stripper plates were subjected to reaction forces by the adjacent kernels, pull force and shear force by corn cob. As the impact force was related to the impact time according to the theorem of impulse, the paper analyzed collision model between corn ear and stripper plates in the snapping process. A mathematical model was obtained about the impact time and intrinsic parameters of the system. The impact time was dependent on system mass, stiffness coefficient and damping coefficient, which lays on the mechanical structure and materials of collision objects. So, the impact force would decrease as the impact time could be prolonged by reducing the stiffness coefficient and raising the damping coefficient. The quantity of shed kernels could be reduced consequently. The paper proposed a corn head with wheel type rigid-flexible coupling snapping device to reduce loss. The corn head consisted of the frame, gear-box, snapping rolls, gathering chain, wheel type rigid-flexible coupling snapping device, and chain wheels. The wheel type rigid-flexible coupling snapping device consisted of snapping wheel axle, spring seat axle, supporting axle, buffer spring, and snapping wheel frame. Force analysis was conducted on the snapping wheel. According to the force conditions and dimension boundary condition, the structure diameters of snapping wheel, snapping wheel frame, and buffer spring were confirmed. In order to obtain the optimal parameters with the minimum loss rate of wheel type rigid-flexible coupling snapping device, the optimization experiments were conducted of the factors at 3 different levels. In the optimization experiments, the snapping wheel radius was designed at 10, 15 and 20 mm respectively, the flexible body thickness was at 2, 4 and 6 mm respectively, the snapping rolls rotating speed at 700, 800 and 900 r/min respectively. The Response Surface Analysis method was used to design the experiments. The software Design-Expert 8.0.6.1 was used to analyze the data. Regression equation was induced according to the experiment and analysis above. The optimal combination of wheel type coupling snapping device was as follows: The snapping rolls rotating speed was 700 r/min, the snapping wheel radius was 15 mm, the flexible body thickness was 4 mm. Verification contrast test was conducted between corn head with wheel type rigid-flexible coupling snapping device and the one with snapping rolls and stripper plates on corns at different moisture contents. As the kernels moisture contents were 21.8%, 16.7% and 13.4%, the grain loss rate decreased 53.4%, 48.6% and 47.0% respectively. This study provides not only theoretical basis but also design reference for the improvement of corn harvester design. [ABSTRACT FROM AUTHOR]

A hybrid refrigeration system of refrigerator car was designed in this paper. Photovoltaic energy storage system was the auxiliary power source of the refrigeration system and it drove the refrigerator during refrigerator car parking for a long time midway or at night. Engine drove refrigerator when refrigerator car was driving. The experimental analysis of hybrid refrigeration system of refrigerator car found that power generation of solar panels could only keep electric compressor working for 4.13 hours in one day. The power generation was not enough to support refrigeration system working for all night and this would affect the quality of cargo in the refrigerated carriage. In order to solve this problem, on the one hand, the energy consumption of refrigeration system needed to be reduced. On the other hand, the power generation capacity should be increased. Firstly, mathematical model of the hybrid refrigeration system of refrigerator car was established. Then, experiments about photovoltaic energy storage system and refrigeration system have been down. Correctness of the model was verified by comparing experimental data and simulation data. On this basis, the refrigeration efficiency and economic coefficient of photovoltaic power generation were put forward as the system evaluation indexes in this paper. The refrigeration efficiency was the ratio of energy consumption to cooling capacity and represented the energy consumption of the refrigeration system. If the refrigeration efficiency is lower, the energy saving of the refrigeration system is more. The economic coefficient of photovoltaic power generation is the ratio of power generation of solar panels to the power capacity of batteries and it represents the power generation capacity of per-unit cost of photovoltaic energy storage system. If the economic coefficient of photovoltaic power generation is greater, the power generation capacity per unit cost of photovoltaic power generation system is more. The two evaluation indexes were unified as the objective function. Nine constraints were enumerated. Based on chaotic ant colony algorithm, the hybrid refrigeration system of refrigerator car was optimized. The results after optimization showed that the energy consumption of the refrigeration system was reduced by 238.63 W, the cooling capacity was increased by 103.11 W and the refrigeration efficiency was reduced from 0.542 to 0.402. The optimized refrigeration system was more energy-saving. The volume of optimized refrigeration system was smaller, which made refrigeration system easier to install on the refrigerator car. Also, the power capacity of batteries was decreased by 2.67 kW·h, the whole day power generation capacity of solar panels was increased from 4.45 to 5.82 kW·h and the economic coefficient of photovoltaic power generation was increased from 0.464 to 0.840. In summary, the optimized hybrid refrigeration system of refrigerator car was more energy-efficient and economical. The optimization method and encouraging results in this paper will provide a fundamental reference for optimization design of the research on solar refrigeration system. [ABSTRACT FROM AUTHOR]

Sowing opener is one of the key parts of seeders, and its working performance affects the seeding quality. Domestic and foreign scholars have done a great deal of research on sowing openers in terms of traction resistance, soil disturbance, soil return performance and blocking performance. But there are few reports on the research of sowing opener for the integrative structure of ditching, earthing and suppressing. In this paper, an integrated sowing opener, which can be used to ditch, earth and suppress, was designed. It can solve the problems such as large disturbance of soil, insufficient compactness of seed bed soil, and poor uniformity of sowing depth. The combination of its sliding knife, retaining plate and repressing wheel can realize the seeding ditch, the seed falling to the bottom of the ditch, the wet soil returning to ditch, the suppressing wheel suppressing the seeding ditch, and the seed being in close contact with the soil. In this paper, the cutting edge curve is analyzed according to the slip cutting principle. It sets the cutting edge curve equation as parabola equation to deduce the conditions which can satisfy the needs of the slide cutting. That is, the slip angle is larger than the friction angle. The final result shows the range of the slider slip angle is 25°-65°. Based on the analysis of the principle of soil reflux after the operation of the trench opener, it can be seen that the change of the obliquity angle of the retaining plate affects the soil disturbance and the soil reflux, and the range of the inclination of retaining soil plate is 0-12.4°. According to the agronomic requirements, the range of soil compactness required for seed growth is 30-50 kPa, and the spring deformation amount is calculated to be 9-15 mm. Finally, the influencing factors can be determined. They are the slip angle, the slope of the retaining plate and the deformation of the spring. The slider slip angle, inclination of retaining soil plate and deformation variables of spring were selected as test factors. Soil compaction and soil disturbance were selected as experimental indices. The optimal parameter combination of the integrated seeding opener obtained from the soil bin text of optimizing the structural parameters was as follows: The slider slip angle was 44.6°, the inclination of retaining soil plate was 3.2° and the deformation variable of spring was 11.8 mm. In order to verify the operation performance of the integrated seeding opener better, field contrast tests were carried out with a double-disc opener and a sharp angle opener under the optimal parameters. The variation coefficient of sowing depth, soil compactness, soil disturbance and backing soil quantity were selected as test indices. The experimental results showed that variation coefficient of sowing depth of the integrated opener was 6.03%, which was 32.4% lower than that of the double-disc opener and 25.2% lower than the sharp angle opener. When the integrated opener was operated, the seeds fell into the ditch prior to the soil, which improved the seeds depth uniformity. The soil compactness was 38.6% higher than that of the double-disc opener and 62.9% higher than that of the sharp angle opener after the working of integrated opener. The suppression part of the integrated opener suppressed the ditches, after the soil-covering ditches were suppressed again by suppressing wheels of the seeder, which increased the soil compaction of the seed bed. The amount of soil disturbance generated by the integrated opener was 16.3% lower than that of the double-disc opener and 36.5% lower than that of the sharp angle opener. But its backing soil quantity was 29.9% higher than that of double-disc opener and 61.5% higher than that of sharp angle opener. Therefore, the integrated opener has little disturbance to the soil. In general, the integrated opener can improve the seedbed environment, enhance soil compaction and improve the uniformity of seeding depth. Besides, this type opener provides an integrated reference for the design of sowing openers. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicles are widely used in agriculture because of the advantages of flexible landing, no contact with plots, and wide adaptability of terrain. Currently, the unmanned aerial vehicle sowing operation is mainly based on the centrifugal sowing device, which mainly relies on the disc to sowing, forming the circular-shape falling area, causing the unstable uniformity of sowing, and it is difficult to control in the direction of the sowing width. In order to meet the needs of unmanned aerial vehicle low-altitude and high-speed sowing operations, and to ensure the uniformity of the sowing, a pneumatic unmanned aerial vehicle sowing device was designed in this paper, making use of the air-flow to blow the seeds out in different directions. The basic working principle was that the seed particles discharged from the metering device were mixed with the high-speed air flow in the flow-spitting box, forming a gas-solid two-phase flow, and then separated into a few streams of seed particles along the diversion channels. The high-spread streams of seed particles, released from the outlet of the diversion channels, cause the formation of a larger width, achieving satisfying sowing presentation. Meanwhile, the key components of the sowing device were simulated and tested. In this paper, the rotor wind field of the multi-rotor unmanned aerial vehicle was simulated and analyzed. The wind field distribution was summarized from two aspects of the vertical plane and the horizontal plane of different heights, and the movement and reasons of the particles in the rotor wind field were analyzed. Three main aspects (the relationship between the outlet size and the wind speed of the air-flow outlets, and the influence of the cone angles of the diversion channel on the airflow, and air pressure distribution in the diversion channel) were studied. The reasons for doing these tests were that the wind speed at the air-flow outlets was the key factor to determine whether the seed can be blown out or not. The design of the diversion channel affected the trajectory of the internal seed particles flow, and the most important thing was the effect on the velocity of the seed when leaving the diversion channel in the size and direction. The effect of the cone angle of the diversion channel on the sowing width and the sowing uniformity was tested. The test results showed that there was a strong negative correlation between the outlet size of the flow-spitting box and the outlet wind speed, and thus, the air outlet size can be determined according to the required wind speed. There was a strong linear correlation between the cone angle and the sowing width of the diversion channel. The correlation coefficient (R2 = 0.999) can be used to determine the appropriate cone angle according to the requirement of sowing width. Considering the distribution of pressure and flow velocity in the diversion channel and the influence on the width and uniformity, 130° was preferred as the cone angle of the diversion channel. Finally, the effects of sowing height on sowing width and sowing uniformity were studied. The correlation analysis method was used to analyze whether the working height in a certain range had an effect on the sowing width. By analyzing the uniformity variation coefficient in the sample areas the effect of working height on sowing uniformity was determined. The results showed that, in the range of 1-2.8 m, the correlation coefficient of height and width was 0.359, greater than 0.05, and the variation coefficient of sowing uniformity was above 15%, and the significance of height and coefficient of variation was 0.197, greater than 0.05, both of which mean that the height of unmanned helicopter had no significant effect on sowing width and sowing uniformity in the range of 1-2.8 m. Therefore, in this range, it is not necessary to consider the effect of the working height fluctuation on the sowing width and uniformity when sowing by this device. In the actual operation, taking into account the sowing width and uniformity coefficient of variation and energy consumption and other factors, the optimal height of 2 m was preferred on the unmanned aerial vehicle. This study provides the basic reference for further optimization of the prototy [ABSTRACT FROM AUTHOR]

Hydropower is one of the most reliable source of green energy and is widely used to meet real-time electricity demand. The ever escalating energy demand and iterative development in hydropower have pushed the generation of hydropower towards a low lost-cost and more flexible state which can work in a wider hydrodynamic region without compromising its performance. So the research on multidisciplinary optimization of hydro turbine needs to be carried out. Francis-type turbine is attractive because the efficiency of the unit at its design point exceeds the other types. As mentioned above, with the needs of robust operation in wide region without compromising its performance, the Francis turbine runner has to be optimized under multidisciplinary constraints. Multidisciplinary optimization technology of Francis runners has always been a key point in the field of turbine research. The coupling strength of each variable is the basis for establishing a concise and efficient multidisciplinary optimization strategy. So in the multidisciplinary optimization of Francis runner, it is necessary to analyze the coupling strength of design variables. In this paper, based on the global relative sensitivity of design variables, a coupling strength analysis method of runner design variables has been presented. First, combing three-dimensional (3D) inverse design theory with curve parametric method, a parametric 3D inverse-design method has been developed to control the Francis runner geometry. According to this parametric 3D inverse-design method, the meridional flow passage and geometry of runner blade can be controlled by a set of discrete parameters. These parameters are treated as runner design variables. The hydraulic efficiency of turbine, the minimal pressure coefficient on runner blade and the maximum static stress of blade are selected as objective functions. Then the global relative sensitivity of each objective function to design variables is calculated by an improved Morris OAT method. Compared with the traditional Morris OAT method, an optimal Latin hypercube design technique is adopted in the improved method. The optimal Latin hypercube design technique has a better space filling property than the traditional one. So the sampling only needs to be done once, which reduces the time of global relative sensitivity analysis without compromising its precision. On the basis of the improved Morris OAT method, the speed of global relative sensitivity calculation is improved obviously. Secondly, the set which contains global relative sensitivity of design variables is treated as universe, and the semi-trapezoidal function in fuzzy mathematics is imported to quantify the membership of each variable to objective functions. After obtaining the membership of each variable, a judgment principle of variable's coupling strength is presented in this paper. According to this judgment principle, the coupling strength property of each design variable can be defined as strong coupling, middle coupling and weak coupling. Finally, based on the coupling strength of each design variable, the multidisciplinary optimization strategy of Francis runner is established. And then the multidisciplinary optimization of Francis runner can be carried out. In order to validate the coupling strength analysis method, an application case is presented in the paper. In that case, the design variables of a Francis turbine runner with the head of 200 m are chosen as the analysis object. From the analysis result, it can be found that only the coupling strength property of maximum thickness is weak coupling, and the others are middle coupling. According to the result, a multidisciplinary optimization strategy is established and used in the optimization of Francis turbine runner. After optimization, both the hydraulic performance and strength property of the optimized runner are improved, demonstrating the effectiveness of the coupling strength analysis method. In conclusion, the method proposed in this paper can be adopted to analyze the coupling strength of design variables of Francis runner. [ABSTRACT FROM AUTHOR]

Sweet potato is an important food crop and energy crop. In order to solve the problems of larger loss rate and high damage rate of 4UZL-1 sweet potato combine harvester during the operation process, a potato connection and conveying mechanism was designed based on the analysis of the structure of 4UZL-1 sweet potato combine harvester and characteristics of domestic sweet potato planting models in this paper. The potato connection and conveying mechanism was mainly composed of a depth limiting mechanism, a digging conveying mechanism, an arc grid conveying mechanism and a scraper chain conveying mechanism. The working parameters were obtained through the kinematic and mechanical analysis of the working process of the mechanism. Aiming at the main evaluation indexes of potato damage rate and loss rate during the transfer and transportation, the Box-Benhnken test was presented on the basis of single-factor test. The angle of the digging conveyor, the conveyor angle of the scraper chain, the conveyor speed of the digging and the conveyor speed of the scraper chain were selected as testing factors. The multiple regression model of evaluation index to each factor was established, and the influence of each factor on operation quality was analyzed, and the optimal structure and operation parameters were obtained. The results showed that the order of the significance influence of factors on potato loss rate from large to small was that the conveyor angle of the scraper chain, the conveyor speed of the digging conveyor, the conveyor speed of the scraper chain and the angle of the digging conveyor. The order of the factors influencing on potato damage rate from large to small was the conveyor speed of the digging, the angle of the digging conveyor, the conveyor speed of the scraper chain and the conveyor angle of the scraper chain. When the forward speed of the machine was 1 m/s, the angle of the digging conveyor was 20°, the conveyor angle of the scraper chain was 68°, the conveyor speed of the digging was 1.2 m/s, and the conveyor speed of the scraper chain was 0.67 m/s, respectively, the potato loss rate was 1.12%, and the potato damage rate was 0.94%. Compared with the predicted values, the relative errors were 3.4% and 1.1%, respectively, the results satisfied the performance requirements of the 4UZL-1 sweet potato combine harvester. The study is benefit for the structure improvement and operation parameters optimization of the sweet potato combine harvester. [ABSTRACT FROM AUTHOR]

In recent years, the pneumatic centralized fertilizing and seeding methods were developing rapidly. The pneumatic centralized fertilizing system was mainly used for layered fertilizing operation. The fertilizing pipes of the fertilizer discharging system were connected with the fertilizer outlet of the layered fertilizing shovel. Under the actions of air flow, the fertilizer was transported to the outlet of the fertilizing shovel quickly and remotely, so as to realize the layered application of the fertilizer in the soil. In this paper, in view of the problems such as the fertilizer falling into the inlet was not smooth and the airflow velocity at the outlet was too high, which leading to fertilizer bounce and dust when the fertilizer discharging system and layered deep fertilizing shovel were combined, the relationship between the structure of each part of the fertilizer discharging system and the working parameters was studied through the test-bench of the pneumatic centralized fertilizer discharging system, and the structure of the fertilizing system was optimized. An air-fertilizer separation device was designed, which was installed between the distributor outlet and the fertilizer discharging pipe of the layered deep fertilization shovel, part of the airflow from the fertilizing system was discharged by the air-fertilizer separation device in advance to reduce the airflow velocity at the fertilizer outlet of fertilizing system. The structure and basic working parameters of each component of fertilizing system were determined through theoretical analysis and parameter calculation. In specific, the airflow velocity of the fertilizing system inlet should be greater than 25 m/s, the diameter of the air-fertilizer conveying pipe, fertilizer inlet and fertilizer outlet was 76, 55 and 20 mm, respectively. The main factors affecting the airflow velocity at fertilizer outlet and inlet of fertilizing system were also determined through analysis. Taking the exhaust outlet area of the air-fertilizer separation device (A), the airflow velocity of the fertilizing system inlet (B) and the fertilizing rate (C) as the test factors, the quadratic regression rotary orthogonal platform experiment was conducted. According to the test results, the mathematical regression model between the test indexes and the influencing factors was established. The results showed that the exhaust outlet area of air-fertilizer separation device, airflow velocity of the fertilizing system inlet and fertilizing rate had a significant effect on airflow velocity at fertilizer outlet of fertilizing system, and exhaust outlet area of air-fertilizer separation device had a significant effect on the airflow velocity at inlet of fertilizing system. The optimized parameters were conducted by fitting and optimizing the test results. It was obtained that airflow velocity at fertilizer outlet, fertilizer inlet of fertilizing system was 5.91 and 3.94 m/s, respectively, the exhaust outlet area of the air-fertilizer separation device, airflow velocity of the fertilizing system inlet and fertilizing rate were 798.0 mm², 28.10 m/s and 0.28 kg/s, respectively. The verification test results showed that the airflow velocity at fertilizer outlet and fertilizer inlet of the system was 6.02 and 4.11 m/s, the fertilizer at the inlet of the fertilizer discharging system falled smoothly and stably. [ABSTRACT FROM AUTHOR]

To solve the problems of low removal rate and incomplete separation for the current longitudinal-axial-flow combined harvester in the case of harvesting rice and wheat, a segmented longitudinal-axial-flow threshing device was designed in this paper. The threshing device mainly comprised a tapered threshing roller, a concave sieve with adjustable threshing strength, a 360° separation device and an electric control system for operating parameters. Through the single factor tests, the optimal switching states of the concave sieve with adjustable threshing strength for rice and wheat threshing was obtained respectively. In order to find out the influence rule of the working parameters of the device on the threshing effects and the optimal parameter combination, the multi-objective optimization tests were carried out. The rotational speed of roller, the angle of deflector, the threshing gap of concave sieve, the separation gap of concave sieve and the feeding rate were selected as the influence factors and the crushing rate, impurity rate and loss rate were selected as the test indexes. The test results showed that the significant sequence of influence of threshing parameters on the crushing rate was the rotational speed of roller, the threshing gap of concave sieve, the angle of deflector, the feeding rate, the separation gap of concave sieve. The significant sequence of influence of threshing parameters on impurity rate was the rotational speed of roller, the angle of deflector, the threshing gap of concave sieve, the feeding rate, the separation gap of concave sieve. The significant sequence of influence of threshing parameters on loss rate was the rotational speed of roller, the angle of deflector, the threshing gap of concave sieve, the feeding rate, the separation gap of concave sieve. Through multi-objective parameter optimization analysis, the optimal working parameters combination for wheat threshing were determined that the rotational speed of roller was 905 r/min, the angle of deflector was 69°, the threshing gap of concave sieve was 18 mm, the separation gap of concave sieve was 19 mm and the feeding rate was 4 kg/s. The field verification tests were carried out using the optimal working parameters combination. The results indicated that the crushing rate was reduced from 1.46% to 1.00%, the impurity rate was reduced from 1.85% to 1.43% and the loss rate was reduced from 1.72% to 1.20% compared with the conventional longitudinal-axial-flow threshing device. All the relative errors between the measured values and the optimized values were less than 5%, the working indicators met the requirements of relevant national standards. The device effectively solved the problems of high crushing rate, unclean threshing and incomplete separation, the research results can provide reference for the structural improvement and operation parameters optimization of the threshing device of longitudinal-axial-flow combined harvester. [ABSTRACT FROM AUTHOR]

In recent years, with the development of various types of intelligent robots, new agricultural robots have become frontier technology in the field of international agricultural machinery. And as the complexity and diversity of the agricultural production and operation, the characteristics of advancement and practicability are needed to add to the agricultural robots. In this paper, in order to increase the automation level of agricultural operations and improve the ability of adapting to different working environments, a novel kinematically redundant planar parallel mechanism (PM) with continuous rotational axis and fewer joints is proposed, which has one rotational degree of freedom (DOF) and 2 translational DOFs (2T1R). For the rotational DOF, the rotational axes of the moving platform are mutually parallel at any position of the whole workspace; for the translational DOFs, the directions are simple horizontal and vertical. This robot has a quite simple structure. As we all know, simple structures of the robot can reduce the manufacturing cost to a great extent. This kinematically redundant planar PM is a metamorphic mechanism. For instant, when the moving platform and the intermediate link are locked, the PM becomes an actuation redundant PM. So this PM can be used to research not only the kinematically redundant property but also the actuation redundant property. Actually, this new type PM can be used in the field of food packaging, seed selection, fruit classification, transport, picking, and so on. For the purpose of improving the robot properties, 15 5-DOF hybrid serial-parallel manipulators are constructed on the basis of this type of planar PM. One of these manipulators is selected to do some analysis in this paper, which is more likely to be applied in agriculture. Firstly, the kinematic model of the 5-DOF hybrid manipulator is established. Especially, the forward and inverse kinematics models show the briefness of this robot. What is worth mentioning is that a simple kinematics model is conducive to realize the control of the robot. And this matches the strategy of robot intelligence. The velocity Jacobian matrix is deduced, the singularity analysis of the PM is done according to the Jacobian matrix, and the conditions for reducing singularity are listed. The concept of singularity degree is defined, which can be used to keep away from mechanism singularity. Then based on the flexibility performance index, the optimal design of the 2T1R planar PM is investigated and the performance atlas is drawn. From the performance atlas, we can choose the physical dimensions of the PM. The 3-dimentional model based on a set of optimal physical dimensions is established. After that, in order to reduce weight without the loss of stiffness, the structural topology optimization is accomplished by means of the finite element software. The analysis and comparison of the whole structure are also carried out. This novel hybrid manipulator has the characteristics of simple structure, simple kinematic model, high stiffness, and high degree of modularity, which provides a very variety of application prospects in the field of agricultural machinery. [ABSTRACT FROM AUTHOR]

The rice-wheat cropping system is the main grain production model in many areas of China, especially in Jiangsu with the area of about 1.8×106 hm2. In other provinces of China along the Yangtze River valley, such as Sichuan, Anhui and Hubei, there are large areas of such cropping system. However, the rice straw processing before wheat planting has caused some problems in these places. As straw burning is forbidden by the government, straw incorporated to field is an available alternative method to process the rice straw. Traditionally, rice straw should be smashed and buried before wheat planting, which requires time and energy. Also, burying rice straw in soil will influence the growing of wheat if the seed stay on the straw. Furthermore, the soil nutrient will be consumed during straw decomposing. The clean area planting technology under full straw cropland, invented by Nanjing Research Institute for Agricultural Mechanization, Ministry of Agriculture and Rural Affairs, China, can complete seeding and straw mulching in the same time, which is a good method to deal with the straw processing problem. However, as the quantity of rice straw is relatively larger than any other straw, the excess rice straw mulching will impact the emergence of wheat, which is likely to cause low yield. To solve the problem, in this paper, we provided the rice straw processing model of part burying and part mulching based on the clean area planting technology under full straw cropland. Then, different straw distributed retention devices with different structures, including flat board with horizontal upward opening, oblique board with horizontal downward opening, flat board with several longitudinal openings and curved board with several longitudinal openings, were designed and introduced respectively. After the tests of these distributed retention devices under different parameters, the structure of curved board with several longitudinal openings was selected as the best one. On the basis of structural development, the central composite test method was used to optimize the key parameters of straw distributed retention device. The gross width of longitudinal opening, quantity of longitudinal opening and revolving speed of picking and smashing device were taken as the influencing factors. The variable coefficient of uniformity and deviation rate of distribution were taken as response values in the experimental study. Orthogonal rotational quadratic combination test with three factors and three levels was made to evaluate the combined influence of the factors on the test index value. Furthermore, regression equations to describe the relationships between the factors and each assessment index were established by using the regression analysis and response surface analysis with the software Design-Expert 8.0.6. The optimum combination of the selected parameters was obtained and verified, and the experimental verification of the mathematical model was also conducted. The results showed that trial factors had great effects on the performance of straw distributed retention device. The significant effects of quantity of longitudinal opening, gross width of longitudinal opening and revolving speed of picking and smashing device on reducing the variable coefficient of uniformity were in a decreasing order. The significant effects of gross width of longitudinal opening, quantity of longitudinal opening and revolving speed of picking and smashing device on reducing the deviation rate of distribution were in a decreasing order. The best parameters of the integrated straw distributed retention were as follows: when the gross width of longitudinal opening was 600mm, the quantity of longitudinal opening was 7 and the revolving speed of picking and smashing device was 1900r/min, the variable coefficient of uniformity and deviation rate of distribution were 18.75% and 0 respectively. The model validation tests were repeated for 3 times on the simulation field by using the optimization results, the values of practical variable coefficient of uniformity and deviation rate of distribution were 19.68% and 0 respectively. The percentage points of absolute error between the experimental and predicted values of variable coefficient of uniformity and deviation rate of distribution were 0.93 percentage point and 0.33 percentage point respectively, which indicated a reasonable choice of optimization conditions. The research results can provide references of technology and equipment for wheat planting after the harvest of rice in rice-wheat cropping system area in China. [ABSTRACT FROM AUTHOR]

Astragalus smicus, 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, it has the advantages of reducing fertilizer input, improving soil fertility, increasing crop yield and quality, and protecting ecological environment, and has strong nitrogen fixation ability and high utilization efficiency. In recent years, the production machinery of Astragalus smicus has been developed and applied rapidly in terms of capacity and utilization efficiency, but its development still lags behind. Ditching and sowing are important links in the production of Astragalus smicus. The yield of Astragalus smicus is largely determined by the quality of sowing, and ditching operation can make Astragalus smicus grow well in low-humid field with poor drainage or sandy soil with poor fertilizer and water retention. Astragalus smicus is often used as green manure in paddy field, but high stubble retention, large amount of straw, insufficient in sowing height of existing other sowing equipments, working parts easily clogged, etc., bring difficulties for mechanized production of Astragalus smicus. In order to solve the influence of machine-harvested rice stubble on mechanized production of Astragalus smicus, aiming at the problems of low quality and low production efficiency in independent ditching and sowing links at present, a Astragalus smicus ditching and sowing machine which suitable for machine-harvested rice stubble field was developed. A height adjustable sowing device was designed, by which the sowing components could be lifted to a proper position according to the residual straw situation in the field. The special seed-metering wheel and quantitative evenly-sowed device for Astragalus smicus were developed to achieve precision sowing and improve the sowing uniformity. The structure and working parameters of the double-disk ditching components were determined. The variation coefficients of ditching width and depth determined by field experiments were less than 6%, which met the drainage requirements of Astragalus smicus growth process. The multiple factor experiments and regression analysis of the test data were carried out by Design-expert software, the results showed that forward speed of machine, rotation speed of seed-metering wheel, seed-uniforming cylinder diameter significantly affected the sowing performance, the results of variance analysis showed that the rotation speed of seed-metering wheel had the greatest influence on the emergence rate and coefficient of variation of sowing uniformity, while the forward speed of machine had the least influence on the emergence rate and coefficient of variation of seed-metering quantity consistency, regarding the coefficient of variation of sowing uniformity, the most influential factor was seed-uniforming cylinder diameter, and the minimum impact factor was the rotation speed of seed-metering wheel, the optimal factor parameters combination which affected the sowing quality of Astragalus smicus ditching and sowing machine was as follows: forward speed of machine was 4.6 km/h, rotation speed of seed-metering wheel was 44 r/min, seed-uniforming cylinder diameter was 6 mm. Verified by field experiments, the Astragalus smicus emergence rate was 95.87%, quantity consistency was 12.7%, coefficient of variation of sowing uniformity was 8.07% in the condition of optimal parameter combination, the relative error was below 3% compared with optimal values predicted by the model. Compared with the existing sowing methods of Astragalus smicus, working efficiency of the designed ditching and sowing machine was 1 hm2/h, which was superior to the artificial sowding working efficiency of 0.1 to 0.125 hm2/h, the hand-shaking working efficiency of 0.2 to 0.3 hm2/h and the motorized sowing working efficiency of 0.5 to 0. 8 hm2/h, and was lower than the UAV sowing working efficiency of 3 to 4 hm2/h. In addition, the coefficient of variation of sowing uniformity and the combination type of ditching and sowing machine were also significantly superior to that of other methods. The Astragalus smicus ditching and sowing machine developed in the paper integrated ditching and sowing links in one operation, the working efficiency was greatly improved, the research provided a new method for Astragalus smicus ditching and sowing machine for machine-harvested rice stubble field. [ABSTRACT FROM AUTHOR]

Laying duck raising and duck egg processing belong to traditional superior animal husbandry in China. Dirty surface of duck eggs will shorten storage time and increase subsequent cleaning cost. The bottom wire mesh is an important part of the furnished cage and is closely related to duck egg cleanliness. Aiming to solve the problem that the surface of duck egg shell is seriously polluted during the process of raising laying duck in the cascading cage-rearing equipment, the authors optimized the dimension parameters of the bottom wire mesh in this paper. Based on the analysis of duck egg movement on the bottom wire mesh, a kinematics simulation mode was developed to determine the appropriate range of the bottom wire mesh slope using dichotomy depending on whether duck eggs roll out of the furnished cage. The steeper the slope, the easier it was for the duck eggs to roll onto the conveyor belt. But if the slope was too large, the duck eggs might collide with the egg on the conveyor belt to cause damage. Meeting the above conditions, the appropriate slope value was chosen. According to the longitudinal spacing in bottom wire mesh, the lateral spacing in bottom wire mesh, the diameter in bottom wire mesh, the total deformation maximum and the mass of the bottom wire mesh, mathematical optimization model of the bottom wire mesh was established. The authors adopted an analysis method of 3 factors and 4 levels corresponding surface, and the dimension parameters of the bottom wire mesh were optimized based on the total deformation maximum response surface. The optimum solution in the results had the maximum area of the leakage hole in the bottom wire mesh. The finite element software ANSYS Workbench was used as the computing platform in this analysis. After optimization, the slope increased to 8.5°, the area of the leakage hole increased by 29.2%, and the total deformation maximum decreased by 18.1%. The area of the leakage hole bears on the cleanliness of the duck egg, the larger the area, the cleaner they were. This was because that duck dropping passed through the hole and fell onto the manure without sticking to the bottom wire mesh to soil the duck egg. Smaller deformation meant better structural stability. To test the feasibility of the optimization result, this research team experimented on cage-rearing laying duck using the bottom wire mesh optimized in a welfare duck farm of Hubei Shendan Healthy Food Company. The experiment included 384 ducks weighting in (1 350±50) g and lasted for a whole month. Ducks were divided into test group and control group living in the same environment. 2 ducks were raised in every cage. The results showed that the bottom wire mesh had a significant positive effect on duck egg cleanliness (P<0.01), and the average cleanliness of duck egg in the test group was 1.21 which was lower than 2.01 in the control group. It’s known that cleanliness had negative correlation with effect. Before and after optimization, the bottom wire mesh had no significant effect on duck feather damage, laying rate and duck egg breakage rate. During the experiment, there was no obvious mass duck leg injuries in the experimental group, and the rate of death and elimination were in a reasonable interval in comparison with the average in the farm. This study solved the problem that the surface of duck egg shell was seriously polluted, and has high practical value. Meanwhile, this research method can provide reference for the development of furnished cage wire for poultry cage-rearing equipment. [ABSTRACT FROM AUTHOR]

For transplanting vegetables plug seedlings, it is difficult to directly pick up seedlings from the tray cells. Damages of root lumps of plug seedling happen all the time in extracting. In this paper, a root lump loosening mechanism using air jets to eject vegetable plug seedlings making for transplanting was designed and evaluated. It consisted of air jets, a linear module, a double-rod cylinder, a control system and some other supporting parts. The step transmission of the air jet along the horizontal direction was performed using the linear module, which was a synchronous belt system. The air jet′ motion along the vertical direction up and down for ejecting plug seedlings was moved by the double-rod cylinder. For high blowing rates, wholes rows of air jets aiming for each drain hole was designed. In this arrangement, the seedlings could be loosened row by row. With a row of air jets blowing the seedling plugs from the drain holes of the tray cells, air pressures along with the force of the plungers effectively loosened seedlings. It would be good for manual pulling seedlings or automatically picking up seedlings from the tray cells. Based on the integrated design and analysis, the air pressure range of succeeding in loosening seedling plugs was 0.098-0.235 MPa using the air jet at the diameter of 5 mm. Under this condition, the seedlings appeared to be most effective in the loosening and not in destroy of the root soil. Meanwhile, the air jet could eject each drain hole at the bottom of the 128-cell tray. Being the first prototype, its optimal machine parameters were examined under various conditions. In the optimum tests, it was found that the air pressure of the air jet plungers exerted the greatest effect on the integrated ratio in loosening seedling plugs, and followed by the moisture content. Other factors such as the seedling age, the air flow rate and the air jet with sponges or not had no significant effects on the integrated ratio in loosening seedling plugs. In reality, it would probably be a moderate air blast for blowing of the plug seedlings from the tray. If the moisture content of root lumps of the plug seedlings was less than 55%, the cohesion forces between the roots and the tray cell walls would increase. In this case, wetting the roots might serve to reduce the adhesion making for blowing. For cucumbers seedlings, when the air pressure of the air jet plungers was 0.2 MPa, the root zone moisture was 55%-60%, the seedling age was 25 d, the airflow circuit was fully open at the outlet of 4 mm, and the air jet had no sponges, the best intact rate succeeding in loosening root lumps of plug seedlings was achieved. Finally, the overall loosening performance test was carried out. The intact rate of seedling and root lump in loosening root lumps by blowing was more than 96%. It needed about 48 s for finishing loosening the whole tray of plug seedling. The loosening mechanism using air jets to eject vegetable plug seedlings has a good performance, which can meet the actual requirements. [ABSTRACT FROM AUTHOR]

The widely use of plastic film mulching technology in agriculture increase crop yields and farmers' income. However, with the extensive use of plastic film, the residual film in the soil is also accumulating yearly, and the accumulated residual film is hard to be removed from soil. If the residual film in soil plough layer can-not be timely treated, it will lead to soil fertility decline, resulting in crop yield reduction and soil contamination. Therefore, it is an urgent issue to remove the residual film from soil, especially in the tillage layer. In order to solve the problem of remnant film recovery, according to the characteristics of the remnant film recovery machine, and according to the requirements of the agronomy of plastic film recovery, a chain-tooth residual film recovery machine is designed and manufactured. It is expected that the transport of membrane-soil, reverse separation of membrane-soil and membrane-collecting process can be completed. In this paper, we studied the influence of the parameters of the reverse membrane-soil separator of the chain-tooth residual membrane recovery machine on the separating effect of the membrane-soil. By analyzing the influence of the parameters on the performance of the reverse membrane-soil separator of the chain-tooth residual membrane recovery machine, the optimal working parameters were obtained, which could provide reference for the follow-up study and optimization of the membrane-soil separator. Aiming at the problems of poor mechanical properties of residual film deposited in the soil plough layer for many years, difficult separation of membrane and soil, and low recovery rate of residual film debris, a chain-tooth residual film recovery machine was designed. The main working parts of the machine are picking up device and membrane soil separating device. The working depth of the machine is 0-150 mm. The pickup device completes the membrane pickup and conveys the soil with the plastic membrane. Then the residual membrane is separated by the reverse membrane soil separating device, and finally the residual membrane is transported to the membrane collector. Taking angular velocity of pickup device, angular velocity of membrane-soil separator and angle of membrane-soil separator as experimental factors, quadratic regression orthogonal test of three factors and three levels was carried out in this study on chain-tooth residual membrane recovery machine with response values of residual membrane recovery rate and soil content. The response surface model of each factor was obtained by experiment, and the influence of each factor on the operation effect was analyzed and optimized. The results showed that the order of the factors affecting the recovery of residual membrane was: angle of membrane-soil separator > angular velocity of pickup device > angular velocity of membrane-soil separator. The order of the factors affecting the soil content was: angle of membrane-soil separator > angular velocity of membrane-soil separator > angular velocity of pickup device; and the optimized results were tested. The results showed that the recovery rate of residual membrane was 81.12% and the soil content was 34.83% when the angular velocity of the pickup device was 42 rad/s, the angular velocity of the membrane-soil separator was 57 rad/s and the angle of the membrane-soil separator was 37°, and the relative error between the experimental value of each evaluation index and the optimized value of the model was less than 5%. The reverse membrane-soil separator can solve the problems of difficult membrane-soil separation and low recovery rate of residual membrane fragments. It can provide a reference for further research and optimization of membrane-soil separator mechanism of residual membrane recovery machine. [ABSTRACT FROM AUTHOR]

In China, Camellia oleifera fruit is deeply loved by consumers as specific woody oil resource. Because of the composition of fatty acid for camellia seed oil is highly similar to olive oil, it is also known as “Oriental olive oil”. However, the shelling operation of Camellia oleifera fruit largely relies on natural drying, which is of low efficiency, high labor intensity, high processing cost, and great dependence on weather. In order to improve the performance of shelling machine for Camellia oleifera fruit, increase the shelling rate and reduce the seed breaking rate, choosing the shelling rate and seed breaking rate as the indices, 3 aspects were studied based on the existing shelling equipment and practical engineering experience in this paper. Firstly, the physical parameters of Camellia oleifera fruit were studied. The parameters such as density, bulk density, grain size, water content and proportion of each component of Camellia oleifera fruit from Changning City were measured, which provided the data for the design of shelling machine parts. Secondly, the mechanism and main structure of the shelling machine were studied. In the beginning, the merits and defects of commonly-used methods for shelling were summed based on their working principle and mechanism. According to practical engineering experience and the measured data above, the final squeeze-rub shelling method for Camellia oleifera fruit was determined. Then the structure of main parts was designed, which included the shelling device consisting of the roller, annular plate and the regulating mechanism, and the separation device consisting of stirring shaft and circular groove structure screen. Finally, the three-dimensional (3D) prototype model was established and the drawing design was completed. Thirdly, the operating parameters of shelling machine for Camellia oleifera fruit were studied. The shelling machine for Camellia oleifera fruit was manufactured based on the structure design, and then the operating parameters’ optimization test was made. In the experiment, Camellia oleifera fruit’s shelling gap, speed of shelling motor, speed of separation motor were taken as single factors, respectively, and the shelling rate and seed breaking rate were taken as indices. The influence trend of these factors on the indices was drew out. Based on the result, the orthogonal experiment was designed, which aimed at studying the effects of the speed of shelling motor, the speed of separation motor and the gap of shelling on shelling rate and seed breaking rate. The results indicated that the water contents of the fresh Camellia oleifera fruit, shell and seed were 60.08%, 74.55% and 45.60%, respectively. The particle size distribution was 20-50 mm, and the bulk density was 0.52 kg/L. The optimal combination parameters were that the speed of shelling motor was 125 r/min, the speed of separation motor was 343 r/min and the shelling gap was 12 mm. And under the condition, the shelling rate was 96.91%, the seed breaking rate was 3.38% and the production capacity was up to 2 t/h. The optimal parameters achieved in this paper can provide reference and technical support for the actual application of shelling machine for Camellia oleifera fruit. And it will benefit the processing industry of Camellia oleifera fruit. [ABSTRACT FROM AUTHOR]

Today, ridge tillage method is an effective farming method that can resist the drought and flood in the northeast area of China. Because of the climate and natural conditions, most of the northeast area of China will continue to adopt ridge tillage method. In the case of ridge planting, no-till can improve the ground temperature, and can control the summer flood and drainage. In recent years the strip rotary tillage type no tillage planter has been extended. Because of the rotary tillage, the root stubble is broken and the anti-blocking performance is good. However, the soil tillage intensity is between 6.5 and 7.8, and the tillage destroys the original ridge, and forms the new ditch. At present, the number of no tillage finger clip type precision seeding and fertilizing machine applied in the production, is about 3000 in the northeast area of China, and the soil tillage intensity index is 1, which reduces the soil tillage intensity and produces no new ditch; but the two-row machine has the complete machine weight of 1000 kg, which brings too large compaction on soil, and makes ridge stand almost flat, therefore, wheel rut compaction seriously affects maize root growth. This machine not only loses the advantage of ridge planting, increases soil hardness, but also enhances manufacturing cost, and makes the price per machine high. The cost of the field operation is greatly improved, which does not accord with the requirements of energy saving and emission reduction in agricultural production. For no tillage planter, the current problem is the existence of the problem remains a ridge shape. Aiming at the requirement of researching and developing new no tillage planter for the conservation tillage corn ridge agricultural technology in the northeast area in China, based on the Archimedes spiral theory, this paper analyzes the notched disc knife break crop performance and the technical requirements to stubble breaking cutter for ideal seed bed, optimizes the spiral notched disk break stubble cutter structure and carries out the optimal selection of parameter; and develops the stubble breaking ditching device and stubble breaking anti-blocking device. Through test verification of stubble breaking ditching device, it opens a "V"-shape groove, and 2 pieces of spiral-notch disc cutters have a diameter of 350 mm, when sowing depth is 40 mm, sowing and ditching width is 28 mm. Increasing the weight makes the stubble breaking ditching device achieve a weight of 100 kg, and in the area implementing high stubble conservation tillage mode and with a field coverage rate of 30%, stubble breaking ditching device can be adopted instead of the conventional planter seeding furrow opener, and ordinary seeder can realize no tillage planting. When stubble breaking anti-blocking device’s breaking stubble depth is between 70 and 100 mm, ditching width is 40-50 mm, and ridge cleaning width of ridge cleaning parts is 210 mm, which are up to the requirement of agricultural technology. Increasing the weight makes the monolithic disc broken stubble device achieve a weight of 113 kg in the area implementing conservation tillage of high stubble breaking rod cover mode and with covering rate of 1 kg/m2, stubble breaking anti-blocking device can be adopted, and ordinary seeder can realize no tillage planting. In this paper, the development of the rolling disc coulter and its edge is Archimedes spiral gap, after test for many times, stubble cutting resistance is small, the weight of machines can be reduced, because it is a passive anti-blocking device, keeping the shape of ridge. [ABSTRACT FROM AUTHOR]

At present, in the trellis vineyard, the methods of mechanical weeding are mainly divided into inter-row mechanical weeding and intra-row mechanical weeding. The development of intra-row mechanical weeding is relatively slow, because the identification and location for crop and weed is difficult in the process of mechanical weeding. Now, the theoretical study on intra-row mechanical weeding of trellis cultivated grape is not very much. In order to achieve the intra-row weeding of trellis cultivated grape, this paper designs an auto obstacle avoidance mechanism based on the existing weeder, which includes parallel four-bar linkage mechanism and trigger mechanism of obstacle avoidance. The contact rod is composed by 2 straight lines and an arc connecting straight lines in the trigger mechanism of obstacle avoidance. And the theoretical working principle of auto obstacle avoidance mechanism is described. After the pre-test, it is found that the length of the straight section of the first section of the rod, the arc angle of the intermediate transition arc and the 3 distances between the contact rod and the edge of the weeding part have obvious effect on the result of weeding. So a virtual prototype model for auto obstacle avoidance mechanism is built in ADAMS, and the trigger mechanism of obstacle avoidance is parameterized. Then, the orthogonal test is conducted by taking the combination of 3 distances between contact rod and edge of weeding part and the length of the first part of the rod as the test factors and the area which is not covered by the weeding parts after the work as the experimental index. The results show that the combination of 3 distances and its interaction with the arc angle of intermediate transition are significant factors. In order to analyze the effect of the combination of 3 distances on the area not covered by the weeding parts after the work deeply, the length of the first part of the rod is set as 1050 mm, the arc angle of intermediate transition is 85°the forward speed is 390 mm/s, the initial velocity of the cylinder is 50 mm/s, and furtherly taking the parameter the combination of 3 distances as the test factor and the area not covered by weeding parts after the work as the experimental index, the optimization simulation is conducted. The results show that the optimal value is obtained when the 3 distances between contact rod and edge of weeding part are 225, 300, and 212 mm, respectively. The area not covered is 783 mm2except the scheduled area which is not needed to weed. It is very small, so the weeds can be considered to be removed completely, which shows the result of weeding is good. On the basis of simulation optimization, the field tests of single obstacle avoidance and continuous obstacle avoidance are also carried out, in which the combination of 3 structural parameters of the obstacle avoidance mechanism is set as variable and the parameters such as length of the first part of the rod and arc angle of the intermediate transition arc as constant values. The field test results show that the average coverage rate of weeding operation after optimization is 97.5%, which is about 8% higher than before, and the standard deviation is 2.98%, which is lower than before. The stability of weeding is also better, and the effect of optimization is obvious. Generally, this study enriches the method of identification and location for crops and weeds in the process of mechanical weeding, and also provides reference for the improvement of the design of intra-row weeder for trellis cultivated grape. [ABSTRACT FROM AUTHOR]

In annual double cropping areas in northern China, the straw is directly returned to the field after maize harvest, and the wheat is sown by no-tillage planter. However, the high water content and strong toughness of maize straw result in the low qualification rate of traditional rotary flail knife type returning machine, which can easily lead to straw blocking and thereby affect wheat sowing quality. To address the above problems, in this paper, a chopping method based on the principle of four-bar linkage mechanism was put forward. The maize straw was chopped using ground as the support. A chopping-type straw returning machine, composed of the frame, pressure roller, transmission device and straw cutting device, was developed. The pressure roller was located at the front of the machine, and was designed to press the standing or lying straws forward in the direction of machine movement. The cutting device was at the back of the roller, and was designed to cut the lying parallel straw into segments. To avoid straw blocking, maize straw was chopped into segments with the length less than 6 cm, and the length was half of the narrow row spacing of wheat. Based on theoretical calculation and motion simulation, the size of 4-link mechanism of cutting device was designed and the cutters' movement trajectory was optimized. In 4-link mechanism, the minimum transmission angle was 70°, the maximum swing angle of rocker was 20°, the eccentric distance of eccentric wheel was 80 mm, and the lengths of cutter holder (connecting rod) and rocker were 267.375 and 460.702 mm, respectively. The distance between the rotation center of eccentric wheel and the hinge point of rocker on frame was 526.627 mm. According to the finite element static analysis by using ANSYS software, the maximum stress of the cutter was calculated as 162 MPa generated near the bolt holes on both sides, which met the design requirements. The field performance experiment was conducted in Hebei Province to compare the chopping-type straw returning machine and traditional flail knife type machine. The comparison and research objects included the unqualified rate of straw length, working stability, soil physical property and the subsequent sowing operation effect. The experiment results showed that the average length of the straw with the designed machine was 4.8 cm, the unqualified rate was 6% and the coefficient of variation was 0.209, which were all superior to the traditional machine. The vibration of the designed one was slightly larger than that of traditional one with no significant difference, and both of the machines worked stably. The cutting depth of new cutter reached 7.71 cm averagely, and soil bulk density in 0-10 cm depth decreased obviously. The subsequent wheat seeding experiments were carried out, and the results showed that there was no straw blocking during seeding when the seeder operated on the surface on which the chop-cutting straw returning machine worked, and the coefficient of sowing depth was 92.5% and it was significantly higher than another one. This study provides a new equipment for the maize straw returning in the double cropping areas in northern China, and it is also conducive to the popularization of straw returning technology. [ABSTRACT FROM AUTHOR]

A new grooved-roller seed metering device is developed to overcome the breakage of seedling, obtain high sowing rate and raise seeding efficiency in present, and exercise the optimal design. Firstly, this paper introduces the main structure, the working principle and the related structural parameters of the device in detail. Seed metering device is a key component to realize mechanized cultivation of Pennisetum, which is divided into 2 types according to its working principle. One type is real-time cutting seed metering device and the other type is pre-cut seed metering device. Compared with real-time cutting metering device, pre-cut seed metering device has the advantages of high automation, no damage to seed and lower labor intensity, so it shows a good market prospect and is the main trend of the future development of the metering device. The grooved-roller seed metering device is one of pre-cut seed metering devices. In terms of the stem stress state of seeding process, the evaluation function of seeding smoothness with force angle of the stem as the target was derived. According to the function, opening width of the seed groove and depth of the seed groove were the main impact factors of the improved device’s seeding performance. Based on the compressive strength of the stem, the best size of seeding slot was deduced as 20 mm × 20 mm finally. The different morphology and difference of seed diameters are the main influence factors of the problem, and those are easy to cause the bud break. The smoothness and accuracy of seeding were improved by adding the elastic dunnages on the groove of the seeding drum. According to the evaluation function of seeding smoothness, the structure size of the dunnages was optimized as the side gasket thickness of 4 mm and the bottom gasket thickness of 8 mm. In order to study the effect of dunnages on the fluency, the model of grooved-roller seed metering device of the Pennisetum was established by using the dynamic simulation software ADAMS (automatic dynamic analysis of mechanical systems). The effect regularities of structural parameters and motion parameters on seed groove and dunnages were studied. The simulations showed that the new seed metering device could realize the orderly discharge of seeds, and obviously reduce the stress of small-diameter seed by using the plastic dunnages, ensuring the seed row stability and the adaptability of seed diameter. Then the real tests in the laboratory and field were undertaken to verify the conclusions of virtual tests. Bench test results showed that the gasket could improve the flow degree of the seed row to a certain extent, in which the roller speed fluctuation ratio was less than 10%, the roller torque fluctuation ratio was less than 400%, and the seeding rhythm fluctuation ratio was about 20%. The research further indicated that the quality of the seeding was not affected by the roller speed, and sometimes the faster speed would slightly improve the fluidity of the seeding. Because when the roller speed was faster, the time the stem entered the entry took shorter, which reduced the resistance of the seed row to a certain extent. The results indicated that the seed metering device can realize the seeding operation and the dunnages can effectively improve the seeding fluency. Field experiment indicated that the seeder was stable, and the qualified index was greater than 93.33%, the missing index was less than 4.1%, the multiple index was less than 2.5%, and the variance coefficient was13.63%. The indicators were in line with the planting requirements of giant grass. The research provides a theoretical reference for the design of grooved-roller seed metering device of Pennisetum and the technical reference for the related design of planting machine. [ABSTRACT FROM AUTHOR]

The study of corn mechanization planting orientation is still in the primary stage. Design of relevant institutions is mostly based on conceptual design of ideal grain shape, and the study on the basic characteristics and basic theory on corn particle swarm oriented alignment technology is lack. The motion state is more complex and affects the oriented alignment effects of maize grain seriously in electromagnetic vibration modes on maize grain in line in the process of conveying and sorting grain. Understanding of mechanical properties and optimization of vibration source parameters are the premise and key to get better oriented alignment effect of maize grain in the study of maize grain in vibration field. At first, this paper established the model of maize grain sliding motion through the force analysis of corn grain in the electromagnetic vibration system, and also obtained the minimum amplitude of the system of 0.05 mm which was the critical condition of contacts between the kernel and platform. Secondly, considering the special physical characteristics of corn grain, 1000 grains for each kind among 5 different kinds of corn with high quality in directional cultivation conditions were selected, and the instruments were adopted, such as the electronic balance with precision electronic scale of 0.01 g, the BPG-9.30AH electric thermostat blast drying box and MXD-01 friction coefficient instrument. For the different types of maize grains, the measured water content is in the range of 13.88%-14.53%, the density range is 1.13-1.19 g/cm3, and the sliding friction coefficient range between corn and hard rubber is 0.58-0.79. The corn planting orientation still relies on artificial pendulum, lacking mechanized corn directional seeding device. In order to make corn group oriented alignment system achieve directional cultivation, directional seeding accuracy requirements, and design parameters of the electromagnetic vibration system for corn particle swarm oriented alignment performance, were analyzed, as well as kinematics and dynamics of the system. The relationship between seed oriented alignment process and design parameters of system was explored in order to satisfy critical conditions requirements; the selected parameters had significant influence on the working performance of the system, and the main parameters affecting the performance of oriented alignment were the direction angle of vibration, vibration amplitude and frequency. On the corn particle swarm oriented alignment test platform, through the 2 orthogonal rotation design tests with 3 factors, the design parameters were optimized, and the factor and test index (directional success rate, the success rate of the entire column) regression equation was established. The optimal design parameters range was as follows: Vibrating direction angle was 32°-35°, amplitude was 0.1-0.15, and vibration frequency was 51.5-52 Hz; corresponding to the test index, directional success rate was in the range of 63.8%-67.4%, the success rate of entire column was 95.8%-96.3%; the optimal combination of design parameters was the vibration direction angle of 34.42°, the amplitude of 0.14 mm and the vibration frequency of 51.77 Hz. The best combination of parameters was used in system verification test, with the high speed camera system implementation of recording and analysis on grain oriented alignment process, and in the absence of mechanical assisted mechanism, the average success rate of the orientation reached 66.2%, the success rate of entire column was 97.4%. The research can provide reference for the directional planting of maize grain and the development of directional seedling-raising equipment. [ABSTRACT FROM AUTHOR]

With the increasing use of the agricultural plastic film, the pollution it brings is also becoming more and more serious. Therefore, design and experiment on plastic film collector of ridged peanut mean great significance to us, of course, facing huge problems. Mechanical recycling plastic film can overcome shortcomings of the great labor intensity and low efficiency using artificial picking up. However the existing plastic film recycling equipments are generally designed based on experiences and have no precise theoretical researches for components, and there are some issues including unreliable picking up performance and unloading mechanism and serious wear of working parts. This paper focuses on the lack of effective automatic removing mechanism for teeth type residue plastic film collector, and according to this situation, automatic removing and smooth returning mechanism for teeth type residue plastic film collector have been designed. Teeth type residue plastic film collector with self-motion unloading mechanism consists of frame, hydraulic shaft fixture, hydraulic fixing bracket, rake, self-motion unloading square tube, hydraulic device, and self-motion unloading scraper. The stability, reliability, and returning smoothness of the motion of the parallel 4-rod linkage mechanism are analyzed. We design a variety of different forms of squeegees to test, and at last find the best form of squeegee named V-shaped. The key part of the mechanism is focused and the stress analysis is performed. Teeth are persistently distorted when they are working. We design 3 types of squeegees including horizontal squeegee, U-shaped squeegee, and V-shaped squeegee, and at last we find the V-shaped squeegee can ensure that teeth are put back in origin place, so it can achieve the best results. The design and innovation of the hydraulic system are also important. We choose single-rod hydraulic cyclinder of 45# steel, the size of hydraulic cyclinder diameter is 40 mm, and the size of piston rod diameter is 25 mm. We use the stress analysis on squeegee, and the movement analysis on planar linkage, and find the movement track of the squeegee at last. Based on this, the objective function and constraints are determined, and the major influencing factors of teeth type residue plastic film collector with self-motion unloading mechanism are the space between teeth and squeegee, squeegee angle, and automatic removing mechanism angle. We do experiment in Jiaozhou, Qingdao, China, the previous crop is peanut, and moisture content of soil is 16%. The experiment and response surface analysis are done for the space between teeth and squeegee, squeegee angle, and automatic removing mechanism angle. The data are then processed, and the parameters are optimized by the response surface method with Design Expert. The response surface analysis of the model shows that the effect of the 3 factors on the primary film removal rate is significant. The order of influencing factors is: the space between teeth and squeegee > squeegee angle > automatic removing mechanism angle. The machine is optimized by the function of optimization of Design Expert, the space between teeth and squeegee is 2 mm, the squeegee angle is 70°, and the automatic removing mechanism angle is 60°. Through the field test, which shows the feasibility of the optimization scheme and will provide theoretical basis for the optimization of related machines. The teeth type residue plastic film collector of ridged peanut has a good film removal effect, which meets the design requirements of plastic recyling machine. [ABSTRACT FROM AUTHOR]

Sweet potato is an important food crop and can also be used as raw material for foodstuffs, animal feed and raw materials for renewable energy. Furthermore, research shows that it has anti-cancer effects. As sweet potato vines are long and difficult to be separated. The vines cleaned up before sweet potatoes harvest has a great role in promoting to improve the quality of sweet potato and the sweet potato harvest efficiency. In order to alleviate the shortage of sweet potato vines crushing machine in the hilly areas of China, the walking sweet potato vines crushing machine was designed in this paper. Based on the analysis of the whole structure, we expatiated on the working principle of the sweet potato crushing machine, and analyzed the structure of key components such as crushed parts, anti-wear technology, ground lifting mechanism and transmission mechanism. Before the machine started to work, the ground clearance needed to be adjusted based on the width and height of the ridge. The high ground clearance leaded to the long stubble height and poor operating effect, but the low ground clearance leaded to damage the sweet potato and increase power consumption. Sweet potato vines breaking qualified rate, stubble height and damaging rate were the main indicators of evaluating sweet potato vines crushing machine. The Box-Benhnken central composite experimental design principle was used on the basis of single factor experiment to study the working parameters of walking sweet potato vines crushing machine. The cutter roller speed, the ground clearance and the distance between blades were taken as three factors which influenced the working quality, and a three-factor and three-level response surface experiment was conducted. The mathematical model of the response surface was established, and the influence of each factor on the machine quality of the operation was analyzed and optimized. The result showed that when the roller rotation speed was high, the ground clearance was small and there was a moderate distance between blades. As such, the overall impact trend of the vines breaking quality rate was high and the stubble heights was low. When the roller rotation speed was small, the ground clearance was high and there was a moderate distance between blades, and the overall impact trend of the rate of the damage was small. The experiment results also showed that the order of the factors affecting of the vines breaking quality rate was: roller rotation speed >ground clearance >distance between blades The order of the main factors affecting of the stubble heights was: ground clearance >roller rotation speed >distance between blades The order of the main factors affecting of the rate of the damage was: ground clearance >roller rotation speed >distance between blades. In 2016, a three-time repeated test for verifying the exactness of the model was conducted on the Nanjing Research Institute for Agricultural Mechanization Ministry of Agriculture of Baima testing site. The field test showed that the optimum parameters were: 1950 r/min for the rotation speed, 25 mm for the ground clearance and 40 mm for the distance between blades, 94.88% for the rate of vines breaking qualified rate, 47.08 mm for the stubble heights, and 0.23% for the rate of damage. By comparing the mathematical model and the experimental result, the error range was less than 5%, which meant that the model established was reliable and could be used for optimization. The results can provide a reference for the structural design and optimization of the operating parameters of the walking sweet potato vines crushing machine. [ABSTRACT FROM AUTHOR]

The traditional way to develop agricultural machinery parts, in which the test of feasibility of agricultural machinery parts is confirmed by manufacturing prototype machinery, is unable to meet the needs of agricultural production due to its shortcomings such as the long development cycle, the heavy workload and the low efficiency. Therefore, it’s necessary to design and implement a digital design platform that combines mechanical analysis with computer simulation technology, and the design effect of agricultural machinery parts can be tested by using this platform instead of manufacturing prototype machinery. Therefore, a digital design software platform for agricultural machinery components i.e. AgriDEM (agricultural discrete element method) is designed and implemented through integrating CAD (computer aided design) with a self-developed analysis software based on the coupling of DEM-CFD-MBK (discrete element method, computational fluid dynamics, multi-body kinematics). The AgriDEM has 4 modules, i.e. boundary modeling, particle modeling, calculation, and visualization and analysis. Boundary modeling module can transform a CAD software design of agricultural machinery into an analysis model that can participate DEM calculation and DEM-CFD-MBK coupling calculation by the secondary development of CAD software or the read of the STL (standard template library) file. Particle modeling module is a software that can establish three-dimensional (3D) spherical particle models, 3D non-spherical particle models, 3D corn grain models, 3D soybean grain models, 3D wheat plant models, and so on. Non-spherical particle were filled with spherical particle. Calculation module is a software that can calculate the working process of agricultural machinery including the fluid process of particles and the contact conditions between the particles, separately with DEM or with the coupling of DEM-CFD-MBK. Visualization and analysis module is a software that can make calculation result visualized and analyze the performance of agricultural machinery. These 4 parts are coupled together by database or data file. During the development of the AgriDEM, C++ language is used to write code, and VS2010+MFC is chosen as the development platform. This platform can simulate, analyze and evaluate the working performance and working process of agricultural machinery in the design stage; by changing the CAD model of agricultural machinery parts, the working process with different principle, different structures and sizes of components and the work performance were evaluated and analyzed, so as to realize the optimization of agricultural machinery parts’ structure and size parameters. The architecture of this platform is described in detail in this paper, and the implementation methods of the key technologies are introduced, including the modeling method of the boundaries model, the modeling method of the particles, the parallel computing method based on OpenMP, the module encapsulation method based on DLL (dynamic link library), and the development method of prototype system. Finally, the feasibility and the effectiveness of this platform are confirmed through testing instances. The new method in this study can provide the reference for the optimization design and digital design of agricultural machinery parts. [ABSTRACT FROM AUTHOR]

In order to better realize the combination of agricultural machinery and agronomy, the design of precision rice hill-drop drilling machine was further optimized and tested. The precision rice hill-drop drilling machine that was powered with high speed transplanter chassis was composed of frame, furrowing and ridging device, height and horizontal profiling mechanism system, power transmission system, seeding device and hydraulic lifting frame. It could meet the rice direct seeding agronomic requirements which are furrowing and ridging synchronously, adjustable sowing rate and hill space, optional row space, profiling seeding mode and stubble burying before seeding. The combined hole-type metering device included small and big type holes was used for the precision rice hill-drop drilling machine, so that it could meet the sowing rate requirement of conventional rice and hybrid rice simultaneously and adjust the seeding rate quickly. On the basis of the combination of agricultural machinery and agronomy as well as the experimental verification, the frame, reduction gearbox, horizontal profiling mechanism, height profiling system and installation angle of slide plate were optimized. The new frame could protect the main bar from being bended. The new reduction gearbox made the hill space to match the speed of the chassis more accurately and also could change the rotation direction to fit different kinds of chassis. The height and horizontal profiling mechanism made the seeding machine more floatable, so it could adapt more complicate ground. Furthermore, the related experiments proved that profiling system is conducive to the seedling emergence of rice. The seedling emergence rates of the rice varieties XS134 and PZTF, which were seeded by the precision rice hill-drop machine with horizontal profiling mechanism, were 7.8% and 8.7% higher than that without horizontal profiling mechanism, respectively. In order to protect the atmosphere environment, the government introduced the relevant policies and laws to prohibit the burning of straw, and promoted the comprehensive utilization of crop straw. Many farmers returned straw residue to field to improve soil fertility and reduce environmental pollution, but it could be more difficult for the direct seeding machine and rice transplanter working in the field as well. To overcome this difficulty, the stubble-burying seeding was studied. The angle of the slide board was confirmed as 4° by the experiment result, while the efficiency of stubble burying was 91.6% and the furrowing and ridging effect under 4° was relatively better than that under other degrees. In this paper, some verification tests involved the main technical indices of the seeding machine and its reliability. Results showed that, the pure work efficiency was 0.67 hm2/h, the qualified rate of hill space was up to 100%, the variable coefficient was as low as 2.5%, the qualified rate of the seeds number per hill reached 95% and the cavity rate was 0; furthermore, the variable coefficient of the consistency of seeding quantity per row and the stability of total seeding quantity were 3.8% and 1.5% respectively; after seeding with horizontal profiling mechanism, the height difference between the left and the right field surface was about 2.0 cm; more important, the average of assignment before first-time fault (MTTFF) was 30.4 hm2/h, and the validity reached up to 98.2%. Therefore, on the basis of these results which all meet the national standard and the requirements of the combination of agricultural machinery and agronomy, and the reduction gearbox makes the machine+ more universal. The performance of the optimized precision rice hill-drop drilling machine is reliable and has exciting application foreground. [ABSTRACT FROM AUTHOR]

For higher volumetric efficiency and lower launch cost of gear pumps with ultra low viscosity working medium used in spacecraft. In this paper, the volumetric efficiency formula of gear pumps was firstly derived from the two main leakages of axial gap and radial gap, At the same time, a new contact ratio factor formula appropriate for undercut gear and standard gear was proposed by the estimation of limited meshing point in driven gear or driving gear. When the undercut point of driven gear was being meshed, if the corresponding meshing pressure angle of driving gear was less than the addendum pressure angle, which showed that the addendum point of driving gear couldn't be meshed, the contact ratio of gear pair should be calculated by the undercut point position of driven gear; conversely, it showed that the undercut point of driven gear couldn't be meshed, the contact ratio should be calculated by the addendum point position of driving gear. Secondly, based on the newly created volumetric efficiency formula and contact ratio factor formula, and the optimal design method theory, with the 2 key parameters i.e. the minimum allowable volumetric efficiency of 90% and the ultra low viscosity value of 0.00018 Pa·s, the optimization design model was established, which took the minimum unit displacement volume being equivalent to the pump weight as the optimization goal. By the optimization of basis parameters of gear pairs including modulus, tooth number, addendum coefficient, pressure angle and displacement factor, the volumetric efficiency decline problem was consequently solved, and the minimum space launch cost of pump weight was guaranteed. Thirdly, the effects of structural parameters of gear pumps on the optimization result were analyzed. All optimization results showed that if the usual addendum contact ratio factor formula of driving gear was used for calculating contact ratio factor in the optimization design model, with the optimized basis gear parameters, the actual contact ratio factor was -0.3429, which was not reliable for undercut gear, and the continuous gear transmission also couldn't be guaranteed, so only the newly created contact ratio factor formula was reliable; the influence degrees of the pump parameters including pressure angle, shaft radius, tip radius of rack cutter, and starting angle of transition region on the optimization result were respectively 6.07%, 7.8%, 2.9% and 6.4%. On the whole, these parameters had little influence on the optimization result; especially, the free space was endowed to the structure design to reduce the radial force. But the influences of radial gap and axial gap on the optimization result were very large, and unexpectedly, there was no optimal solution with the axial gap value of 0.06 mm, so the upper limit values of radial gap and axial gap could be determined by the influence turning points. For example, the upper limit value of axial gap was 0.04 mm, and the upper limit value of radial gap was 0.07 mm. For other pump parameters, there were such turning points. For example, the upper limit value of shaft radius was 13 mm, and the upper limit value of starting angle of transition region was 180°. As a whole, the designed pump shape had a small axial size and a large radial size. Finally, the first attempt of the optimal gear pump design for spacecraft clarified that the ultra low viscosity medium was also applicable to gear pumps, and catered to the development of Chinese aerospace industry. The study provides a demonstration of the optimal design method for other hydraulic pumps with ultra low viscosity medium as well. [ABSTRACT FROM AUTHOR]

Notoginseng is one of rare medicinal herbs in China, and it is mainly grown in Yunnan Province. Market demand of notoginseng is very large, and hence, until December 2014, the planting area of notoginseng has reached 40000 hm2. At present, the main planting pattern is through manual operation, and the labor intensity is very high and the sowing quality is discrepant. However, there is no precision seeding device suitable for notoginseng. Therefore, the mechanization planting of notoginseng has important practical significance. Notoginseng is planted on small plots of land, the planting density and the requirement of seeding precision are high, so we designed a small sized precision metering device. The liquidity of the seeds is not good and the shape of seeds is irregular for notoginseng, so we chose the pneumatic seed-metering device to adapt to the characteristics of the seeds accordingly. In order to meet the precision seeding requirements of notoginseng planting, a unique pneumatic cylinder-type precision metering device was designed. This device integrated the features of vacuum suction, insulated pressure for seed-clearing and zero speed of seed dropping. In this paper, the main structure and the working principle of the metering device were expounded. The pitch-row of the hollow shaft was determined and the stability of the flow field was ensured by the flow field analysis through the computational fluid dynamics (CFD) software. The key structure parameters were determined through theoretical calculation according to planting requirements. The contrast test of dropping seed indicated that zero speed of seed dropping was necessity. According to the extensive testing combined with the experimental results of relevant scholars, the main factors which affected seeding performance of pneumatic cylinder precision seed-metering device were determined, which were forward velocity, negative pressure and adsorption angle. During the test process, in order to reach zero speed of seed dropping, the installation angle of adjustable insulated pressure plate was changed with forward velocity. The notoginseng seeds in Wenshan were chosen for sowing object. Based on the three-factor five-level quadratic orthogonal rotating combination test method, the influences of forward velocity, negative pressure and adsorption angle on sowing performance were explored. The experimental results showed that the influence of negative pressure on the qualified rate was very significant (P<0.01), and the influences of forward velocity and adsorption angle were significant (P<0.05). The regression equations of the 3 factors were fitted through the processing by Design Expert 8.0.6 (experimental design expert) software. Based on the results of examination, we found that the fitting of the equations was good, the best parameter combination was adsorption angle of 20°, negative pressure value of 660-720 Pa and forward velocity of 0.72-0.76 m/s, and under the optimal condition, the qualified index was greater than 90.2, the missing index was less than 4.9, and the multiple index was less than 5.3. The pneumatic cylinder precision seed-metering device met the standard and requirements by comparing the results with the national standard and notoginseng planting requirements. This approach of research is suitable for the exploitation of notoginseng seed-metering, and provides a theoretical reference for the design of pneumatic cylinder precision seed-metering device for Panax notoginseng. [ABSTRACT FROM AUTHOR]

Wheat straw is widely used as a kind of inexpensive, abundant, easily available, and sustainable raw material. At the same time, large amounts of wheat straw have still been burned on farmland in China, and have not been timely and properly applied. The smoke and dust from burning have highly adverse impacts on the environment. Therefore, it is urgent to study the pretreatment technology that is green, environmentally friendly, cost-effective and sustainable. Wheat straw was processed by physical methods, and the obtained raw fibers of wheat straw fiber mulch film were further pretreated by physical methods. In order to explore the influence of pulping process parameters on the pulp properties of the pulped raw fibers wheat straw fiber mulch film and the excellent pulp can be used to produce wheat straw fiber mulch film, the influence law of process parameters on the objective function was studied experimentally in this study. In the experiment, the whole wheat straw was pulverized by a crusher and the raw fibers of wheat straw fiber mulch film were obtained by a self-made straw fibers preparation machine. Taking the soaking water temperature, soaking time, beating time, beating load, and pulp volume as influence factors and the dry tensile index, beating degree and pulp fiber length as response indexes to evaluate the pulp properties. The five-factor and five-level (1/2 type) quadratic regression orthogonal rotation center combination design parameter optimization test method was adopt. The variances were analyzed using Design-Expert V6.0.10, and regression models were established between response indexes and influence factors. The analysis results showed that the beating time and the beating load had a very significant effect on the dry tensile index (P<0.01), and the interaction of various factors has no significant effect on the dry tensile index (P>0.05); the beating time, beating load, and the pulp volume had a very significant effect on the degree of beating (P<0.01), the interaction of soaking water temperature and soaking time had a significant effect on the degree of beating (P<0.05) while the interaction of the soaking water temperature and the pulp volume had a very significant effect on the degree of beating (P<0.01 ); beating time and beating load had a very significant effect on fiber length (P<0.01). The regression model optimization results were the soaking water temperature 63℃, soaking time 2 h, water volume of pulping pool 13.50 L, pulping load 4.57-5.50 kg and pulping time 0.25-0.68 h. Under such an optimized combination conditions, the response indexes of wheat straw fiber mulch film pulp processed as follows: the dry tensile index was greater than 5 Nm/g, the beating degree was less than 50 °SR, and the pulp fiber length was more than 0.9 mm, which indicated that the processed pulp could be used for manufacturing wheat straw fiber mulch film, and the wheat straw fiber mulch film could meet the technical requirements for covering and cultivating crops in wet and dry fields. [ABSTRACT FROM AUTHOR]