Abstract:The automatic navigation technology of agricultural machinery is the basis for the implementation of precision agriculture, which can effectively reduce the labor intensity of agricultural machinery operators, improve the operation accuracy and efficiency. The classic automatic navigation of agricultural machinery includes three key technologies: positioning and attitude measurement, path planning and motion control. Based on the global navigation satellite system, the inertial navigation system, the machine vision navigation system and the multisensor data fusion algorithms, the methods of agricultural machinery positioning and attitude measurement were introduced firstly, and then the global path and local path planning algorithms in the agricultural machinery automatic navigation system were summarized, and the kinematic models, control methods and actuators for steering and braking were analyzed on agricultural machinery. With the development of information technology, the intelligent navigation technology of agricultural machinery had attracted more and more attention. Ensuring the safety of operation and improving the efficiency of cooperation were the key technologies of intelligent navigation of agricultural machinery different from traditional automatic navigation. LiDAR and RGB camera were taking as examples, the autonomous obstacle avoidance technology of agricultural machinery was analyzed, and the cooperative operation technology of multiple agricultural machinery was expounded, including cooperative mode, the perspectives of communication technology, cooperative controlling and remote management platform respectively. Finally, the future development direction of intelligent navigation technology for agricultural machinery was prospected with the specific example of “Hands Free Hectare” and smart agriculture.

Abstract:In order to solve the problem of precise control of droplet diameter variables during aviation spray, the quadratic regression orthogonal experiment and machine learning was used to establish the quadratic residual compensation droplet diameter model. With Aerial-E electricity atomizer as the control object, the quadratic regression orthogonal experiment was carried out on the atomization experiment platform to analyze the correlation between the droplet diameter and the wind speed, flow rate, atomizer speed, and droplet diameter model was established. In order to improve the prediction accuracy, a compensation factor was added to establish the first optimized droplet diameter compensation model. To further improve the prediction accuracy, the second residual prediction model was established by machine learning, the second residual prediction model and the first optimized droplet diameter compensation model were superimposed linearly to obtain the quadratic residual compensation droplet diameter model. In order to verify the validity of the quadratic residual compensation droplet diameter model, the model validation experiment and the comparative experiment were carried out, the results showed that the maximum deviation predicted by the quadratic residual compensation droplet diameter model was 10.78%, the R2 between the predicted and measured values of the quadratic residual compensation droplet diameter model was 0.95, which was 0.06 higher than that of the droplet diameter model and 0.05 higher than that of the first optimized droplet diameter compensation model. The quadratic residual compensation atomization model of electricity atomizer was obtained by equivalent deformation of the quadratic residual compensation droplet diameter model, and an electricity atomization system was designed based on the model. A system application experiment was carried out to verify the practicality of the system, the results showed that the R2 between the expected and the measured value of the droplet diameter was 0.94, and the relative span of droplet was less than 1.6, which could realize the control of the droplet diameter under the condition of stable wind speed and flow rate. The results can realize precise control of droplet diameter variables during aviation spray. 

Abstract:Because of wind stress, the movement trajectory of fog droplet in space was changed, and the deposition distribution of fog droplets on the target surface was changed. In order to study the effect of different factors on this phenomenon, a test of droplet deposition distribution in closed silo was designed. The variables were the transverse wind at different speeds (1m/s, 2m/s and 3m/s), spray height (30cm, 40cm and 50cm) and spray pressure (0.4MPa, 0.6MPa and 0.8MPa). Based on the experimental measurement results of deposition distribution, a bimodal distribution mathematical model based on normal distribution probability density function was established. The physical significance of each coefficient in the model was also explained, and the influence of various horizontal factors on the coefficients in bimodal distribution and influence relationship of each horizontal factor on the coefficient in bimodal distribution were analyzed. This mathematical model can more systematically express the relationship between deposition range and deposition quality. The variation law of deposition parameter k1 was opposite to k2. With the increase of spray height, spray pressure and cross wind speed, k1 was decreased while k2 was increased, and deposition shifted from the first peak distribution to the second peak distribution. The two position parameters μ1 and μ2 of the bimodal distribution had the same variation trend, both increasing with the increase of wind speed and height, and decreasing with the increase of spray pressure. Therefore, increasing the spray pressure can reduce the center drift distance. The range of the first and second peak distributions (scale parameters σ1 and σ2) were increased with the increase of spray height and wind speed, and the deposition distribution was more dispersed. Increasing the spray pressure can effectively reduce the deposition dispersion of the first peak, but it had no effect on the distribution of the second peak. This study investigated the effects of different intensity of transverse wind and spray height and pressure on droplet drift deposition distribution, providing a reference for optimizing pesticide spray technology and improved droplet resistance to drift.

Abstract:The hard bottom layer of the paddy field is not flat, so the rotary tiller will tilt and vibrate when it is working in the field, which will seriously affect the quality and efficiency of the rotary tillage operation and damage the paddy field leveling. In order to solve these problems, a GNSScontrolled intelligent paddy field rotaryleveling machine was developed. The two GNSS satellite antennas were symmetrically fixed at the two ends of the rotaryleveling machine hood, which was used to receive elevation data of the main antenna and pitch angle data between the two antennas. The received elevation positioning data was the elevation of the rotaryleveling machine, and the pitch angle data was the inclination of the rotaryleveling machine. The fuzzyPID control algorithm was used to output driving voltage signal to the electrohydraulic proportional reversing valve, thereby controlling the expansion and contraction of the cylinder, so that the rotaryleveling machine rotated around the intermediate rotating shaft or moved up and down along the chute to realize the horizontal and height adjustment of the implement. In order to solve the problem of continuous heating of the hydraulic pump, a hydraulic system was designed. In this hydraulic system, the accumulator and the hydraulic pump worked together to reduce the burden on the hydraulic pump. A datum calculation method was proposed, which automatically calculated the datum plane by the least squares method to get the control reference plane conveniently and quickly. In order to verify the working performance of the intelligent paddy field rotaryleveling machine, the paddy field leveling test was carried out under different crop types such as rice, wheat and different soil types such as sandy soil, clay soil and loam. The test results showed that under different test conditions, the flatness of the paddy field was greatly improved, and the average can reach about 3cm. The system had good stability and adaptability. After leveling, the paddy field can meet the agronomic requirements of rice planting.

Abstract:In view of the problem that the resistance of the coreshare furrow opener is too large under high speed operation, an optimal design method of furrow opener based on the bionics principle was proposed based on the efficient and low resistance penetration structure of the dogbadger canine tooth surface. China northeast farmed badger was selected as bionic biological samples, it was carried out on the upper right canine of badger advance disinfection after treatment for 3D scanning and obtained the complete point cloud data, and then through the Matlab software, fitting curve of the four best badger canine based on the above four design was obtained and the four kinds of slide furrowing device were processed, finally it was compared with the traditional coreshare furrow opener through contrast test analysis. Under the condition that the operating depth was 50mm, the type of opening device and operating speed were taken as the test factors, the horizontal operating resistance was taken as the main index, and the trench depth, trench width, ridge height and ridge width of the trench device were taken as the secondary index to conduct the soil groove test. The experimental results showed that the resistance of each optimized sliding trench opener was lower than that of the standard coreshare furrow opener at the same operating speed. At operating speed of 3.6km/h, 5.4km/h and 7.2km/h, the operating resistance of the optimal sliding trench device can be reduced by up to 8.04%, 8.15% and 8.71%, respectively, compared with the standard coreshare furrow opener. The variation coefficient of furrow depth, furrow width, side ridge height and side ridge width by standard coreshare furrow openers and optimized sliding furrow openers were all lower than 5%.

Abstract:As the existing rice pot seedling transplanter with fixed rowspacing failed to meet the agronomic requirements of rice transplanting with different rowspaces in the double cropping rice area in south China，a kind of pot seedling transplanting device gearing to the need of variable rowspacing transplanting was accordingly designed based on the existing walking type rice transplanter. Firstly，the optimal pulling angle of pot seedlings and the location of picking and falling determined the trajectory of pot seedlings，and the kinematics model of connecting rod mechanism of picking seedlings was established， the design of the mechanism model was optimized with the help of Matlab. Secondly，according to the motion parameters of the connecting rod mechanism and the motion requirements of the clamping motion posed by the dropping posture of the pot seedling when it was being thrown，the CAM of the clamping motion control was designed，and the motion simulation was carried out to analyze the synchronism of the movement between the connecting rod mechanism and the clamping motion. Then，in order to maintain the consistency of the time when the pot seedlings fell into the paddy field after passing through the transmission tube to ensure the uniform plant spacing during transplanting，the wall inclination angle of the key parameters of the transmission tube was theoretically analyzed and designed. Finally，transplanting experiments were carried out with different seedling speeds and rowspacings，and the average successful rate of seedling extraction reached 89.96% and the average inverted seedling rate was 3.45%，indicating that the device had a good transplanting effect and could be applied to the transplanting of rice pot seedlings with variable row-spacing.

Abstract:A wheel type rigid-flexible coupling snapping device was designed to reduce kernel loss on corn head. There were two forms of rigid-flexible coupling structure in the device, namely, buffer spring and flexible contacting surface. The buffer spring was fixed to play a cushioning role when the snapping rolls were impacted by corn ear, and the flexible contacting surface was fixed on the snapping rolls to decrease hardness. In order to explore the different roles that two kinds of rigid-flexible coupling structure played in loss reducing of the designed snapping device, impact experiments of corn ear were conducted to study the mechanisms. The experiments were carried out on the widely used corn head with deck plates and the corn head with wheel type rigid-flexible coupling snapping device respectively. Each of the snapping devices was equipped with steel surface and flexible contacting surface composed of silicon rubber. The impact velocity was determined according to the typical working conditions of corn harvester. The impact parameters, including impact time, peak acceleration and impulse as well as the mass of detached kernels were collected. The result showed that buffer spring could shorten the impact time. Compared with snapping device equipped with deck plates, the impact time of corn ear on wheel type rigid-flexible coupling snapping device were shortened by 62.2% and 67.3%, corresponding to steel surface and flexible surface, respectively. Moreover, the impulse was decreased by 60.6% and 76.0%, and the detached kernels mass was decreased by 14.4% and 25.6%. On the other hand, flexible surface could reduce the ear’s impact force by prolonging impact time. Compared with the steel surfaces, impact time of corn head with flexible contacting surfaces were prolonged by 78.4% and 53.8% corresponding to corn head with deck plates and the one with wheel type rigid-flexible coupling snapping devices, respectively, which caused the declines of peak impact force by 45.1% and 55.2%, impulse reduction by 19.9% and 51.2%, respectively, and resulted in a decrease of detached kernel mass by 34.1% and 42.8%. The research can provide theoretical basis for the designs aiming to reduce kernel loss of corn head.

Abstract:In order to clarify the effects of straw treatment on the quality of straw returning, tillage preparation, rice growth and yield in Northeast rice region, and conduct a comprehensive evaluation of the benefits, three straw treatment methods were set according to the agronomic requirements of straw returning and different straw treatment equipments. Specifically, three methods were as follows: chopping and spreading at harvesting (CK, combine harvester with chopper cum spreader device), straw treatment 1 after harvesting (T1, combine harvester with chopper cum spreader device + secondary spread), straw treatment 2 after harvesting (T2, combine harvester without chopper cum spreader device + chopping and spreading after harvesting). The experiment monitored the effects of different straw treatment methods on the quality of straw chopping and spreading, the quality of land preparation, the growth of rice and the yield. The experiments showed that all three straw treatment methods could achieve full amount straw returning, which could ensure normal field machinery operation and rice growth. Among them, T2 had the best comprehensive effect, which could achieve better straw chopping and spreading effect, straw burying effect, higher aboveground biomass and yield of rice. In terms of straw chopping and spreading quality, compared with CK and T1, T2 had significant differences in average straw chopping length, qualified rate of straw chopping length, and residue height. Although the unevenness of straw spreading was higher than that of T1, there was no significant difference. In terms of land preparation quality in the subsequent period, compared with CK, the vegetation coverage of T2 below the surface and below 8cm was significantly different, which was better than CK. Compared with T1, there was a significant difference in vegetation coverage below the surface, while there was no significant difference in vegetation coverage below 8cm. In terms of rice growth and yield, the yield of T1 and T2 treatment was 1.5% and 4.4% higher than that of CK, respectively, and the difference of T2 treatment reached a significant level. This study provided a theoretical basis for the selection of rice straw harvesting treatment methods and supporting equipment in Northeast rice region. 

Abstract:Considering the problems, namely crops damage, large hole width and low fertilizer spraying efficiency of deep applicationtype liquid fertilizer hole applicator, a deep applicationtype inclined liquid fertilizer hole applicator was designed. Through the design of “oblique hole pricking and parameter reverse solution”, and based on the humancomputer interaction platform, the pricking hole mechanism of key components was designed, the structure and working parameters of the mechanism were optimized, and the movement form of fertilizer feeding interface of fertilizer spraying needle was analyzed. According to the technical characteristics of spraying fertilizer needle earthing and unearthing fertilizer, and to improve the efficiency of fertilizer delivery, the liquid fertilizer distribution mechanism, which was the key component, was designed by using the combined transmission form of “differential gear train transmission and space cam mechanism”. The movement model of the fertilizer outlet interface was constructed to analyze and satisfy the cooperative movement mechanism with the fertilizer inlet interface and reduce the complicated connection configuration of the fertilizer delivery pipeline. The field performance test of the deep applicationtype inclined liquid fertilizer hole applicator revealed a superior hole punching performance, the fertilizer was sprayed evenly, and the mechanical damage to crops was small. The hole width, crop damage rate, fertilization amount and fertilization depth were 45.0mm, 0.3%, 28.5mL/time and 102mm, respectively. All indexes were less different from the previous design and met the agronomic requirements.

Abstract:Aiming at the problem that it is difficult to directly obtain the threedimensional resistance variation law and soil dynamic behavior characteristics of the soil contact componentneedle body through experiments when the liquid fertilizer hole applicator is pricked with the inclined pricking hole mechanism. By adopting the Drucker-Prager yield criterion to construct the finite element model of hole application soil, the ADAMS kinematics analysis module was applied to obtain the pricking hole track of fertilizer spraying needle of pricking hole mechanism, and ANSYS/LS-DYNA display dynamics software was used to establish the interaction simulation model between fertilizer spraying needle and soil. Taking the maximum pressure on the needle body in the Zaxis direction as the measurement index and the working parameters as the influencing factors, the virtual and bench comparative tests of single way stress on the fertilizer spraying needle were carried out. The results revealed that the pressure was increased first and then decreased with the increase of the advancing speed and the rotation of puncture speed. The simulation and test data were close in size and the change trend was basically the same. Taking the advance speed of the fertilizer spraying needle (062m/s), the rotation speed of the puncture hole (70r/min) and the inclined angle (20°) as the simulation working parameters, the threedimensional resistance of the needle body and the dynamic behavior of the soil were simulated and analyzed. The analysis disclosed that the resistance of the fertilizer spraying needle in the three directions was increased first and then decreased. Within 0~0189s, the process of the fertilizer spraying needle entering the soil, the resistance of the needle body was changed slowly in the Xaxis direction, indicating that the fertilizer spraying disturbed less to the soil in the advancing direction. The resistance of the needle body was increased rapidly in the Zaxis direction, which indicated that the fertilizer spraying needle had a strong impact on the soil. The stress of the soil was mainly concentrated in this direction due to the shear of the needle tip, and the resistance reached the maximum value of 21.69N at 0.189s. The resistance of the needle body in the Yaxis direction was small, which indicated that the squeezing effect of the fertilizer spraying needle on the soil was weak, and the resistance reached the maximum value of 8.56N at 0.189s. Within 0.189~0.214s, the original position of the fertilizer spraying needle swung itself, the resistance of the needle body was increased rapidly in the Xaxis direction, which indicated that fertilizer spraying needle triggered great disturbance to the soil in the advancing direction. The resistance values in the other two directions remained basically unchanged. Within 0.214~0.350s, the excavation of the fertilizer spraying needle, the resistance of the needle in the Zaxis and Yaxis directions were gradually decreased until it became zero. Among them, within 0.214~0.238s, the resistance of the needle body in the Xaxis direction was increased instantly, indicating that fertilizer spraying produced strong extrusion on the soil in the forward direction, reaching the maximum value of 31.87N at 0.238s. During the whole pricking process, the formation of the puncture opening was mainly caused by the swing posture of the fertilizer spraying needle itself and the soil disturbance in the forward direction during the excavation process. Therefore, the resistance of the needle body along the Xaxis direction was influenced significantly, which conformed to the actual pricking hole law. The simulation method of needlesoil interaction provided can be a reference for the optimization design of fertilizer spraying needle and the research of clay characteristics.

Abstract:Inorder to increase the adaptation of garlic harvester to different areas and row spacings, a kind of garlic combine harvester was designed and its key functional parts were also studied in depth. The garlic combine harvester was built by using modularization design methods. The independent harvesting function module had main functions of garlic harvesting such as garlic stem lifter, arrow shaped ripper, belt holding conveyor, garlic stem aligning and cutting device and garlic collector. A 1rowed to nrowed garlic combine harvester may be built by choosing the number of harvesting function module with different conveying units and chassises. At the same time, the spaces between the harvesting function modules may be changed steplessly from 0mm to 300mm, which will be suitable for 70~420mm rowspacing garlics mechanized harvesting. Based on the analyses of the influence factors, the garlic drawing forces’ theoretical model was bulit and its changing rule influenced by the structure parameters was also found out. And the experments proved that the drawing forces would be increased with the enlargement of the garlic stem contact angle which may be changed by the adjustment of the belt tension. The drawing force would be enough for the garlic harvesting after the soil ripping when the synchronous belt tension reached 2800N. Based on the soil ripping forces’ theoretical model, the changing rules influenced by the angle of the arrow shaped ripper to the ground, the penetrating depth of the ripper and the machine moving velocity were also researched in depth. Results of the orthogonal test showed that the penetrating depth of the ripper and the soil moisture content had significant influence on the soil ripping force. The soil ripping force was 520N as the penetrating depth of the ripper was 80mm and the soil moisture content was 30%. Field test results of prototype showed that the technical indicators of the garlic combine harvester met the expected results of design. Its harvesting rate was 98.3%, the loss coefficient which included the damaged and the lost garlic was 3.5% and the production efficiency of 1rowed harvester was 0.14hm2/h.

Abstract:Aiming to improve the automation level and operation performance of sugar beet harvesting machinery in China, reduce the loss of damage and leakage digging, and reduce the labor intensity of personnel, 4LT-A type traction sugar beet combine harvester and 4LTSYT-A autofollow row field simulation experiment platform were developed, and the kinematics analysis of autofollow row system was also carried out. During the tests, the 4LTSYT-A autofollow row field simulation experiment platform was placed under the beet root deviation distance detection mechanism and digging mechanism of the 4LT-A type beet combine harvester, and its power was provided by the variable frequency motor controlled by the control box. The 4LT-A type beet combine harvester was towed and powered by a John Deere 1054 tractor. Single factor bench tests were carried out by taking leakage digging rate, damage rate and response time as the autofollow row performance indexes, and taking reset spring preload force, forward speed, deviation distance, hydraulic flow and oil supply pressure and plant spacing as test factors. The significance and influence of each factor on each performance index were analyzed. The variance analysis and visual analysis of the single factor test results showed that the spring preload force, forward speed, deviation distance and hydraulic flow had significant effects on each performance index, the oil supply pressure and plant spacing had no significant effect on each performance index. With the increase of spring preloading force (range of 53~346N), the response time was increased, and the leakage digging rate and damage rate was firstly decreased and then increased. When the preloading force was 198N, the leakage digging rate and damage rate were the lowest, which were respectively 2.34% and 3.77%. With the increase of forward speed, the leakage digging rate and damage rate were increased gradually, and the response time was decreased gradually and tended to be constant. When the hydraulic flow was changed from 15L/min to 35L/min, the leakage digging rate was gradually decreased, and the response time and damage rate were first decreased and then increased. When the hydraulic flow q=25L/min, the damage rate and response time were the smallest, which were 3.77% and 0.47s, respectively. Each performance index was increased gradually with the increase of deviation distance, and the autofollow row system had a good adaptability to the deviation distance of 0~6cm. This research can provide reference for the later parameter optimization and the research of automatic row harvesting system of beet and other undersoil fruit harvesters.

Abstract:Aimed at problems that currently nonuniform seed sowing, low pass rate, high seed missing rate, great seed wasting and severe seed blocking existed in the seedsowing system of preseedcutting sugarcane planters with wide and narrow row spacing, virtual experiment analysis and practical experiment research were conducted through ADAMS. A kind of preseedcutting seedsowing systems with a single roll bottom sowing edge were designed and developed. The effects of the parameters as the rotation velocity of seedsowing roll, lateral plate angle, flowcontrolling plate elastic structure of the sugarcanegathering box of the seedsowing device and ordered rotating sugarcane gathering on seed sowing properties were studied through the test platform. The following results were turned out according to experiment results: the qualified rate of automatic rotating ordered flow guiding sugarcane gathering was 95.1%, the flowcontrolling plate elastic structure of the sugarcanegathering box of the seedsowing device had significant effects on pass rate of seed sowing, the lateral plate angle and the rotation velocity of seedsowing rolls had generally significant effects. Optimized parameters of the seedsowing device were as follows: using the flowcontrolling plate elastic structure, the lateral plate angle of the sugarcanegathering box was 105°, the rotation velocity of seedsowing rolls was 6r/min (the theoretical seed sowing velocity was 0.83s/stick). Finally, these optimized parameters were validated through experiments, which showed as follows: the average qualified seed sowing rate was 91.0% (the average seed sowing space was 0.917s). The average seed missing rate was 4.5%. The average seed blocking rate was 0.5%. The seed sowing uniformity was improved significantly. What mentioned above laid the theoretical research foundation of deeply further development of preseedcutting sugarcane planters.

Abstract:The change of blade trailing edge shape will affect the wake structure of impeller outflow, which has a significant impact on rotorstator interaction (RSI) in the pump. To study the influence of long and short blades trailing edge shape on performance and rotorstator interaction in centrifugal pump by CFD, long and short blades trailing edge filing was applied on pressure and suction sides with different thicknesses respectively. The numerical simulation was carried out by using the SST-SAS turbulence model, and the accuracy of the simulation was verified by performance and PIV test. Rotorstator interaction in pump was analyzed by pressure fluctuation and vorticity distribution. The results showed that pressure side filing (PSF) can effectively improve the efficiency of centrifugal pump at nominal flow rate, and the greater the filing thickness was, the more remarkable the effect was. On the other hand, PSF can also obviously improve RSI in centrifugal pump at nominal flow rate, so as to reduce the energy loss of pressure fluctuation, improve the performance of centrifugal pump and prolong the service life of blades, while the suction side filing (SSF) greatly aggravated the rotorstator interaction. The distribution of pressure fluctuation and vorticity in frequency domain showed that the main frequency components of RSI in impeller passage were axial frequency and its multiplication, and the main frequency and secondary frequency of RSI in volute passage were fB and 0.5fB respectively. Compared with the main frequency vorticity near the trailing edge of the long and short blades, the effect of the trailing edge filing of short blade was more significant than that of the long blade. Evolution process of the vortices in RSI region demonstrated that the vortices in RSI region during short blade passed through the tongue were more intense compared with long blade, which determined the difference of RSI near the trailing edge of the long and short blades and resulted in a secondary frequency of 0.5fB.

Abstract:Variable angle adjustment is an effective measure which is usually used to widen the operating range of axialflow pump. In order to ensure the adjustability of blade placement angle in bidirectional axialflow pump, a certain clearance will be reserved between blade and hub during structure design of the impeller. The hub clearance will change with the adjustment of the blade installation angle. According to engineering experience, inappropriate size of the hub clearance will significantly affect the hydraulic performance of the axial flow pump. Therefore, the effects of hub clearance on hydraulic performance of bidirectional axialflow pump should be analyzed. Five clearance radii of impeller hub (0mm, 1mm, 3mm, 5mm and 8mm) were designed. Threedimensional Reynoldsaveraged Navier-Stokes equations was solved by CFX to predict external characteristics of bidirectional axialflow pump. The results were verified by experimental data. It was shown that when hub clearance was too large, head and torque of pump were decreased significantly both under forward and reverse condition. The decline of pump efficiency due to increase of hub clearance under large flowrate was more obvious. And the maximum relative decline ratios of pump efficiency under forward and reverse condition were 5.72 percentage points and 3.48 percentage points respectively. In impeller passage, the leakage rate of hub clearance was increased with the increase of clearance radius. Near impeller hub, the axial velocity and circulation of impeller outlet declined remarkable with the increase of clearance radius. This result can provide useful suggestion to structural design of bidirectional axialflow pump.

Abstract:In order to study the influence of gap backflow of fullflow pump impeller on hydraulic performance, the CFD software was used to carry out numerical simulation calculation of the fullflow pump. Then the flow characteristics and hydraulic performance of the fullflow pump were analyzed. Finally, the reliability of numerical calculation data was verified through model tests. There were two research directions：the first one was to study performance difference of the fullflow pump under different flow conditions when the gap was constant. The second one was to study the performance difference of the fullflow pump with different gaps under the design condition. The results showed that the gap size had an obvious impact on the hydraulic performance of fullflow pump. With the increase of gap size, the efficiency and head of the pump devices were reduced under the design condition. When the minimum gap size was 0.65mm, the head of the fullflow pump was 3.05m under the design condition, and the efficiency was 82.46%. The highest efficiency was 82.66%. When the maximum gap size was 2mm, the head of the fullflow pump was 2.92m under the design condition, and the efficiency was 8085%. The highest efficiency was 81.27%. The difference of the head between two pump devices was 0.13m under the design condition, and the difference of the efficiency was 1.61 percentage points. With the increase of the flow rate, the difference of the pressure between inlet and outlet was gradually decreased. The backflow rate was also gradually decreased. The influence of backflow on the impeller was small. And close to the rim, the effect of backflow on the flow regime was great. With the increase of the gap size, the backflow of the fullflow pump was increased. The influence of fullflow pump on flow state was heavy. The working ability of the impeller was worse. The head and efficiency of the fullflow pump were gradually decreased. The research can provide a basis for the design and development of the fullflow pump.

Abstract:Spatiotemporal characteristics of dry-wet change are the key characterization of regional hydrological response under global change. To explore the temporal and spatial distribution characteristics of dry-wet index in Anhui Province under the background of global change, spatiotemporal distribution characteristics of aridity index was comprehensively investigated for 15 meteorological stations during 1957—2016 in Anhui Province. Based on the calculation of potential evapotranspiration (ET0) by the FAO 56 Penman-Monteith model with regional correction mode, the temporal and spatial distribution characteristics, uniformity and stability of the dry—wet index (AI) in Anhui Province in the past 60 years were quantitatively described by the cloud model. The AI and ET0 in Anhui Province showed a downward trend, with propensity rates of -0.006a-1 and -0583mm/a, respectively, and P showed an upward trend of 1155mm/a. The opposite trend of ET0 and P caused the AI to gradually decrease. Anhui Province generally showed a trend of becoming wet. P was the most discrete and had the worst stability compared with ET0 and AI. On the fourseason scale, summerautumn and winter AI, which was dominated by summer (-0.012a-1), was the main feature of dry-wet change in Anhui Province. The AI superentropy value with descending order was summer, autumn, spring and winter, and the uncertainty was gradually reduced. The change entropy of ET0 in the four seasons was lower than the annual average entropy. The ambiguity and randomness of the four seasons’ ET0 were poor. The winter ET0 had the greatest instability. The increase of rain and snow in summer and winter and the decrease of precipitation in spring and autumn were the four seasons’ characteristics in Anhui Province. The main form of the pattern and the summer precipitation were increased significantly (2467mm/a), while showing the greatest unevenness and instability. Spatial scale, AI, and P showed the reference crop evapotranspiration variation gradient of Wannan to Wanbei appeared nonsmooth latitudes phenomenon, the spatial region of each entropy size was higher than the super time series entropy, and the spatial distribution characteristics of AI were more discrete and unstable.

Abstract:The extraction of rice planting area in countylevel depends on the medium and high spatial resolution images of the complete time series. However, it is often difficult to obtain the high spatial resolution images of the complete time series due to the cloud and rain weather and the satellites own visit cycle. Thus causing the problem of low precision in rice planting area based on extraction by single MODIS data. Taking Yuanyang County, an excellent rice planting area in Henan Province, as an example, an enhanced spatial and temporal adaptive reflectance fusion model (ESTARFM) was used to fuse mid and highresolution Landsat data and hightimeresolution MODIS data to obtain the normalized difference vegetation index (NDVI) data of the complete time series. After smoothing by TIMESAT filtering, the characteristics of time series NDVI curves of rice and other features in the study area were used to set reasonable NDVI thresholds. The decision tree classification method was used to extract the rice planting area. The results showed that the overall classification accuracy was 92.23% and the Kappa coefficient was 0.9043. The producer accuracy of rice extraction was 96.73% and the user accuracy was 93.51%, which indicated that the ESTARFM model can well integrate high spatial resolution images, solve the problem of missing data, and provide an effective reference for extracting rice planting area in a countylevel.

Abstract:Advanced topographic laser altimeter system (ATLAS) can provide scientific data for global canopy height measurement. However, due to the characteristics of background noise in the photon data, the traditional algorithm does not study for the forest coverage area under weak beam conditions and there was still few photon cloud noise filtering algorithm can evaluate the accuracy of noise filtering under the condition of weak beam in forest research area. In order to quantify the accuracy of the photon cloud noise filtering algorithm in the forest research area under the condition of weak beam, the accuracies of the local distance statistical algorithm, the densitybased spatial clustering of applications with noise (DBSCAN) algorithm and the particle swarm optimization (PSO)-DBSCAN algorithm for photon cloud noise filtering experiments in forest areas under weak beam conditions were studied, and the influence of different characteristics on noise filtering results was analyzed. The results were as follows: the results showed that PSO-DBSCAN algorithm had the accuracy of noise filtering as 0.95 in the forest area under weak beam conditions, which met the accuracy of photon cloud noise filtering requirements, and the algorithm performed better than the local distance statistical algorithm and the DBSCAN algorithm. The solar elevation angle had greater impact on the noise filtering algorithm than the terrain slope and vegetation coverage.

Abstract:The fine structure inside the canopy of apple tree determines the light distribution and is one of the important factors affecting the quality and yield of apples. Aiming to rapidly generate apple tree canopy 3D reconstruction model to study the illumination distribution in it, a point-leaf model reconstruction method of apple canopy based on point cloud data was proposed. A Trimble TX8 was used as a data acquisition device to obtain 3D point clouds of the canopy in the flowering, leaf growth stage and stable growth stages of apple tree as the research object. Firstly, a leaf spatial location (LSL) extraction approach using densitybased spatial clustering of applications with noise (DBSCAN) and layers Kmeans and median methods was proposed. In the LSL extraction progress, the DBSCAN clustering method based on adaptive parameters was used to extract the point cloud of singleleaf branches. And the same point cloud was sliced into layers, and the Kmeans and median method was used to fit the branch center line. And then, the Euclidean distance of each point between the single blade and the center line was determined, and the point with the smallest Euclidean distance (ELD) was the LSL point. Field experiments showed that the method proposed was suitable for LSL extraction during leaf growth and stable growth stage. Through comparative analysis between the automatical algorithm and artificial use of Realworks software extraction point showed that the average ELD between these two methods was 1.41mm. Secondly, the whole apple tree canopy LSL was extracted by canopy voxelization, and the point model was constructed. Using the leaf templete to splice the LSL, the point-leaf model was formed. The light interception calculation (STAR value) in the VegeSTAR light model showed that the 3D reconstruction efficiency was improved greatly. Therefore, the point-leaf model reconstruction method was effective.

Abstract:In order to explore the effect of depth of convolution layer on feature extraction of kiwi trunk images, a visualization method was proposed to analyze the extracted features. Firstly, the collected data set was classified into positive and negative samples. Taking the area where the trunk and the water pipe intersected in the dataset as positive samples and the remaining areas as negative samples. Input the samples into LeNet, Alexnet, Vgg-16 and the defined three types of shallow structures for training. Then, by extracting the activation map, normalization, and bicubic interpolation visualization methods, the visualization results of the last convolution layer of each classification model were obtained. The comparison can be obtained: Alexnet and Vgg-16 extracted trunk features in the test image, while LeNet and three types of shallow models extracted the trunk, ridge and other features together while extracting the trunk. Finally, the image classification and object detection models of the above six types of network structures as feature extraction layers were used to verify the flowering period and fruiting period data sets, and the accuracy drop caused by changes in the characteristics of the data sets in different seasons was used as the evaluation criterion: the accuracy of image classification shallow model was decreased by more than 15.90 percentage points, Alexnet and Vgg-16 were decreased by 6.94 percentage points and 2.08 percentage points respectively, the accuracy of object detection shallow model was decreased by more than 49.77 percentage points, Alexnet and Vgg-16 were decreased by 22.53 percentage points and 20.54 percentage points respectively. The accuracy of all shallow models was greatly reduced due to changes in the extracted features. This method explained the difference between the feature extraction of the kiwi trunk target from the deep network and the shallow network from the perspective of visualization, and provided a reference for the adjustment of network depth and training samples in subsequent research. 

Abstract:Fruit canopy information collection plays an important role in the orchard variable spray. Aiming at the problem of canopy extraction of fruit trees under background (nongreen plants) and weed disturbance, a canopy segmentation algorithm was proposed based on M-SP feature weighted clustering. The segmentation process can be described as: the original image was converted from RGB color space to HSI color space. The Mahalanobis distance similarity matrix (M) was constructed by calculating the hue (H) and saturation (S) components between fruit tree and the background; moreover, luminance feature (L) was extracted: the vertical position of the pixel was used as the position feature (P). The maximum entropy algorithm was used to extract the shadow region of the image and perform mask processing on the intensity (I) component in the HSI. The obtained shadow region was used as weighted region S of spatial feature, thereby constructing the shadow position weighting. Finally, the acquired M-SP feature matrix was normalized, and the Kmeans clustering of the upper background, the lower background, the fruit canopy and the weeds were respectively performed, and the image segmentation was finally completed. In order to verify the accuracy of the quantitative verification algorithm, precision, recall and F1scores were used to evaluate the image segmentation results under different weed disturbance levels (slight, medium and strong) and time segments (morning, noon and evening). The Kmeans and Gaussian mixture model (GMM) without feature extraction were used respectively as comparative experiments. The results showed that the proposed method was robust to the canopy segmentation of fruit trees under different weed interference levels and different shooting time periods. The average precision was 87.1%, the average recall was 87.7%, and the average F1scores was 87.1%. The segmentation and verification results showed that the algorithm can accurately segment the canopy area of fruit trees, which provided a reference for collecting the canopy information of fruit trees by computer vision.

Abstract:In China, citrus production occupies an important position in agriculture and has great economic benefit. For a long time, most of citrus harvesting relies on manual work, which has low efficiency and high labor cost. The labor cost accounts for almost onehalf of total labor cost in citrus production process. In addition, citrus picking is usually carried out during the day, while makes less use of night time. Therefore, it is of great significance to develop a fruit picking robot working at nighttime. Focusing on citrus picking process, a multiscale convolution neural network named Des-YOLO v3 was proposed and used to detect citrus at nighttime under natural environment. By using ResNet and DenseNet for reference, the Des-YOLO v3 network was designed to realize the reuse and fusion of multilayer features of the network, which strengthened the robustness of small target and overlapping occlusion fruit recognition, and significantly improved the precision of fruit detection. The experimental results showed that the precision, recall rate and F1 value of the Des-YOLO v3 network were 97.67%, 97.46% and 0.976, respectively, while those of YOLO v3 network were 91.41%, 91.10% and 0.913, respectively. At the same time, the mean average precision of the trained model under the test set was 90.75%, and the detection speed was 53f/s, which was 2.27 percentage points and 11f/s higher than those of YOLO v3_DarkNet53, respectively. The final results showed that the Des-YOLO v3 recognition network had stronger robustness and higher detection precision for the recognition of mature citrus in the complex field environment at night, which provided technical support for the visual recognition of citrus picking robot.

Abstract:Modern agricultural equipment is developing towards the intelligent machinery, and deep learning and machine vision are core technologies in realizing the intelligent machinery. In terms of the machinevision based intelligent agricultural machinery that works in maize field, they should forward towards at the maize stem or avoiding the maize stem, while the ability to identify the maize stem accurately is the premise to ensure them work properly. Aiming to distinguish the maize (Zea Mays L.) stems, which grew in the field. In order to acquire the high quality field pictures, one chargecoupled device (CCD) camera was mounted in one camera gimbal. The plugin unit named after LabelImage was applied to mark and label the maize plants, based on the deep learning framework TensorFlow, a convolution neural network model with multiscale hierarchical features was built, and the unit convolution kernel with four times expansion was applied. Thus the maize seedling recognition model was obtained with the recognition accuracy of 9965%. Based on the recognition results, the morphological process was conducted by the OpenCV 342 and the Python 365. The threshold value exerted the major influence on depending the information completeness during the binary process, the pictures that contained the maize seedlings were divided into an optimum parts, then an optimum threshold value for each part would be calculated by the algorithm that described. Inspired by the bounding rectangle of each object was different in the binary picture, the aspect ratio was utilized to distinguish the maize seedling stem, and the minimum aspect ratio was computed, then the corresponding bounding rectangle was filled red which indicated the stems. The field experiment was conducted from June 20th to June 22nd 2018, and totally 10800 pictures were shot during these three days. Five shooting times and six kinds of weed densities were took into consideration for each day. The experimental results showed that the mean identification accuracy was 9893%, and neither the shooting times (P>0.05) nor the weed densities (P>0.05) had significant influence on the recognition accuracies. The research result had applicable value, and it can be used as the upstream technology for the intelligent agricultural equipment.

Abstract:At present, the cutting of seed potatoes is mainly accomplished manually, which caused a series of problems, such as heavy labor intensity, low efficiency and high cost. Thus, the automated cutting of seed potatoes is urgently needed to be solved, especially with the rising cost and decreasing availability of labor. The first and foremost step for automated cutting is the recognition of potato buds. An improved faster region convolutional neural network (Faster R-CNN) scheme was proposed to achieve better recognition performance for potato buds. Data augmentation technique was leveraged to expand the potato dataset. Faster R-CNN model was trained based on the expanded dataset, and experimental results on the test set indicated that the recognition precision was 91.67%, recall rate was 84.09% and F1 was 87.72%. The average running time was 0.183 s. On this basis, an improved Faster R-CNN approach was proposed. Gaussian weight reduction function was adopted to optimize the nonmaximum suppression (NMS) algorithm in Faster R-CNN. For the detection boxes which had overlaps with M greater than or equal to the threshold Nt, the corresponding scores was decayed in the improved Faster R-CNN, rather than setting them to zero in Faster R-CNN. Besides, a strategy of online hard example mining (OHEM) with the optimized NMS algorithm was adopted in the improved Faster R-CNN. Experimental results on the test set demonstrated that the improved Faster R-CNN scheme achieved a precision of 96.32%, a recall rate of 90.85% and an F1 of 93.51%, which were increased by 4.65 percentage points, 6.76 percentage points and 579 percentage points, respectively, compared with Faster R-CNN. Moreover, the average running time of the improved scheme was 0.183s, which was the same to that of Faster R-CNN. Namely, the improved scheme could achieve better recognition performance without incurring any noticeable additional computational overhead, thus satisfying the requirements for realtime processing. Consequently, the improved Faster R-CNN approach was effective for potato bud recognition and could lay a solid foundation for future automated cutting of seed potatoes. 

Abstract:The root phenotypes of different vigorous maize seeds vary a lot, and imaging roots of growing maize is a noninvasive, affordable and high throughput way to detect it. However, due to the block of soil, acquiring a complete image is difficult. An algorithm was proposed to repair incomplete root images and based on it, root fast noninvasive phenotyping detection can be realized. Firstly, a cuboid transparent container without cover was developed as mesocosms and the maize seeds were planted in it. The maize roots grew in soil against two acrylic plastic surfaces due to the press of the small growing area to acquire more root details during roots visualization and imaging. Even though, parts of the roots were occluded by the soil which meant that it was tough to extract the information of root general physical construction. For recovering gaps from disconnected root segments, corrosion growth algorithm was proposed based on the physiological characteristics of hydrotropism, geostrophic and continuity with three steps which were root image thinning, corrosion and growing processing, respectively. The experiments indicated that maize phenotyping parameters were negatively correlated with seed aging days. And specifically, root number, root length, root width and root extension length of unaged and 14dayaged maize seeds were decreased from 14.80, 83.50mm, 1.53mm and 82.70mm to 4.38, 36.90mm, 1.38mm and 54.6mm, and the growing speed of them were changed from 1.68 per day, 8.80mm/d, 0.06mm/d, 9.0mm/d to 0.70 per day, 4.3mm/d, 0.05mm/d and 5.70mm/d, respectively. Whereas root extension angle is basically irrelevant with the level of maize seed aging. The developed cuboid transparent container without cover can push each root growing along the wall of the container which helped to acquire more root information. The presented novel corrosion growth algorithm can recover the missing parts, even for big gaps, of maize roots effectively according to root morphological properties. The experiments showed that the proposed method can be applied to evaluate the vigor of maize seeds which had vast application prospect in high throughput root phenotyping area.

Abstract:In order to monitor the growth of citrus, a method to obtain the complete surface information of single citrus fruit by inspection robot was proposed. LabelMe was used as a tool to mark citrus fruits and segmented branches and trunks, and the model of Mask R-CNN was used to train and recognize them. The 3D information of citrus fruits and segmented branches and trunks can be extracted from the images with depth information taken by Kinect V2 camera. According to the growth of citrus fruit and the occurrence of diseases and insect pests, the surface of citrus fruit was divided into regions, and integrated system was used to describe the information acquisition rate. The CCD camera connected to the end of the manipulator was used to acquire the surface information of the citrus fruit. Three positions of the manipulator were proposed to obtain the complete surface information of the citrus fruit. A prototype inspection robot was built and simulated under the robot operating system (ROS). The process of citrus surface information acquisition in the laboratory environment was proposed. In the laboratory environment, the complete surface information of citrus was obtained by the inspection robot. The experimental results showed that the closer the ratio of horizontal to vertical stems of citrus fruit was to 1, the more complete the outer surface information obtained by photographing was. When the photographing mode of three photographing positions was used, the higher the success rate and work efficiency of avoiding obstacles can be ensured while the citrus surface integrity rate was obtained. The citrus surface information acquisition rate can reach 94.21%, and the average movement time of the manipulator was 86.57s. The research result provided a method for human to get the surface condition of citrus, monitor the growth of citrus and control the diseases and insect pests.

Abstract:Milk is one of the main sources for humans to obtain protein, and dairy industry is also an important pillar industry for agricultural personnel in China to increase their income. Detecting the estrus of dairy cows in time, artfical insemination them at the right time, and reducing cows emptiness are the key means to increase the milk production of dairy farms. As the methods of identifying dairy cow estrus based on physical signs such as activity or body temperature often cause stress reactions of cows and accuracy is also not high enough, a noncontacted automatic method for recognizing estrus behaviors of cows was proposed. In this method, an improved Gaussian mixture model to achieve target detection for moving cows was used. Then, interference images were removed based on the information of color and texture. Next, a cow behavior classification network model based on AlexNet was trained to identify cows’ mounting behavior. Finally, based on the classification model result, automatic recognition of estrus behavior of cows was realized. Experiments on the test video data sets showed that the accuracy rate of the method was 100%, and the recall rate was 88.24%. The method can be used for daily estrus monitoring of dairy farms, and it can also provide support for decisionmaking of their production management. The research can also serve as a reference for the automatic recognition of other large animals’ behaviors.

Abstract:Aiming to achieve an effective identification of dairy cows in a noncontact and highprecision environment of farming, a method to identify dairy cows based on the improved YOLO v3 deep convolutional neural network was proposed. According to this method, multiple cameras were installed above the passageway between the doors of the milking room. The back of cows was videotaped automatically and regularly, after which the image of the cows back was captured by applying video frame decomposition technology. Upon the removal of images noise with bilateral filters and the enhancement of brightness and contrast with the pixel linear transformation method, the individual dairy cows were serial numbered manually. For the cows to be better identified in complex environments, the YOLO v3 recognition model that features optimized anchor boxes and improved network structure was constructed by making reference to the Gaussian YOLO v3 algorithm. From totally 36790 images showing the back of 89 cows, 22074 were randomly selected as the training set, while the remaining ones were classified into either the validation set or the test set. The results showed that the accuracy of the improved YOLO v3 was 9591%, the recall rate was 95.32%, the mAP was 95.16%, the IoU was 85.28%, the actual frame rate of detection was 32f/s, and the accuracy rate of identification was 0.94 percentage points higher compared with that of the YOLO v3 and 1.90 percentage points higher than that of Faster R-CNN. Moreover, the detection speed was eight times faster than that of Faster R-CNN, while the F1 value of dairy cows with pure black back was 2.75 percentage points higher compared with that of the original algorithm. The method showed such advantages as low cost and excellent performance, which were not only conducive to the realtime identification of dairy cows in complex farm environments, but also to the extended application of this method to the identification of other largesized animals. 

Abstract:The control of water pump water supply is an important part of the intelligent irrigation control system. The water supply in the water supply process is beneficial to the development of crop roots and the absorption of minerals in the soil within the optimal control range. In the intelligent irrigation control, due to the nonlinear, timevarying and hysteresis problems of the pump control, the traditional proportion integration differentiation (PID) control is difficult to achieve good control effects. In order to solve the instability problem of pump control in intelligent irrigation system, based on the traditional PID control algorithm, the seeker optimization algorithm (SOA) was used to optimize PID control. The results showed that the optimal control algorithm can effectively solve the problems of nonlinearity, timevarying and hysteresis in the control of intelligent irrigation pumps. In order to verify the actual effect of SOA optimization PID control, it was compared with particle swarm optimization (PSO) optimized PID control and genetic algorithms (GA) optimized PID control. The experimental simulation results showed that the PID control based on SOA optimization had the shortest response time, smallest overshoot, and no oscillation in the steady state process. Therefore, it was suitable for pump control in intelligent irrigation systems.

Abstract:In arid oases irrigation areas, soil secondary salination is one of the main problems leading to land desertification, so as to imperil the soil quality, growing of crops and agricultural production, even leading to abandonment of agricultural soils. Most salinization processes of salt accumulation in irrigated lands are largely determined by the salinity of the irrigation water and the groundwater level in the areas. So it is very crucial to control groundwater and irrigation amount for agricultural development. In order to find out the optimal irrigation amount and reasonable groundwater depth in typical cultivated land in Hetao Irrigation District, field trials were conducted for two consecutive years in 2017 and 2018, and sunflower farmland was selected as the research object, saturatedunsaturated soil moisture and solute motion theory was applied, and HYDRUS-2D numerical model was utilized for numerical simulation of water and salt transport in GSPAC system under different irrigation and groundwater depth conditions in the study area, and analysis of water and salt transport conditions under different irrigation conditions was made to determine the optimal irrigation system and reasonable groundwater depth. The simulation results were compared with the field test results, and the model simulation values were in good agreement with the measured values. The results showed that the optimal irrigation amount in the test area was 82.8~85.5mm, and the reasonable grounding depth of groundwater was 160.72cm. The research can provide a theory basis for rational utilization of water resources and watersalt regulation in arid regions.

Abstract:Crop coefficient is an important parameter for estimating the change of water demand in crop growing season. Based on the meteorological and spring maize observations of 107 meteorological stations in the Northeast China from 1951 to 2018, the spring maize coefficients calculated by the model of crop coefficients were validated by using different crop coefficient correction formulas. The interannual variation trends and spatial distribution characteristics of crop coefficients during the whole period and each growth stage were analyzed by using spatial interpolation. The results showed that the single crop coefficient method considering the influence of wind speed and humidity had the best effect on the simulation of crop coefficient in the early stage of spring maize (R2=0.65). The coefficient of spring maize crops in the full growth period in the Northeast China was varied from 0.756 to 0.815. The spatial distribution of highvalue areas was mainly distributed in the western part of Northeast China, and the lowvalue areas were mainly distributed in the northern part of Heilongjiang Province and the southeastern part of Liaoning Province. Crop coefficients at different fertility stages were the largest in the middle of fertility, followed by the rapid growth period, and the early and late stages of childbearing were generally small. In the past 70 years, the interannual variation of crop coefficient of spring maize in the Northeast China showed a significant downward trend (R2=0.38), and the tendency rate of crop coefficient reached -0.004/(10a). In each reproductive period, the interannual changes of Kc showed a declining trend, Heilongjiang Province had the most obvious decline, followed by Jilin Province and eastern part of Inner Mongolia Autonomous region, changes of Liaoning Province were not obvious. The crop coefficient of most stations in Northeast China showed a decreasing trend, the decreasing trend and the significant decreasing trend accounted for 92.5% and 64.5% respectively. In different growth stages, the decline trend was the most obvious (46.7% in the rapid growth stage), and in the middle and late growth stage (41.1% and 34.6% respectively), the trend of change was not significant at the early stage of birth.

Abstract:Soil thickness is an important parameter affecting soil quality. Rapid acquisition of accurate soil thickness information is an important data basis for the analysis and evaluation of the quality of cultivated land resources and its changing trend. Current mainstream measurement methods are inefficient or inaccurate, such as radar detection method and borehole sampling method. The rapid measurement of soil thickness was realized based on soil mechanical resistance with optimized cone meter. Data were acquired by a cone soil thickness measuring instrument which was an optimized handheld cone meter attached with acceleration sensor, position sensor and other sensors. Acceleration compensation technology was adopted to reduce the measurement error of soil mechanical resistance caused by nonuniform speed penetration of cone meter. Envelope detection and Hilbert instantaneous amplitude eigenvalue clustering algorithm were introduced to identify soil structure and calculate the thickness of soil layer. The simulation results based on Ayers semiempirical model showed that the conical soil thickness measuring instrument based on Hilbert transform algorithm can effectively acquire the information of soil thickness with relative error no higher than 7.50%. The measuring results for outdoor measured data showed that the absolute error of soil thickness measured by Hilbert instantaneous amplitude spectrum based on lower envelope was not more than 1cm, and the relative error was not more than 10%. This method can meet the needs of actual measurement for plough layer soil depth and provide a reference for future soil layer measuring application.

Abstract:Hetao Irrigation District (HID) is a main grain production region in China. Soil salinization and excessive application of chemical fertilizers are main important factors that restricting the food and environmental safety in HID. Reasonable and efficient utilization of fertilizer resources on saline soil to improve crop production efficiency and reduce nonpoint source pollution of nitrogen are the effective ways to relieve the problem. Farmlands with mild (0.460dS/m) and moderate (0.951dS/m) salinization were selected, as a pure nitrogen application rate of 240kg/hm2. The same amount of nitrogen was applied to the different treatments. Five fertilization treatments (the fertilization proportion of organic fertilizer was 0, 25%, 50%, 75% and 100%, respectively) and one blank control were provided, which were designated as U1, U3O1, U1O1, U1O3, O1 and CK, respectively. The field experiment was conducted to explore the response of maize yield to organic nitrogen substituting for inorganic nitrogen fertilizer in different salinized soils, and provide scientific basis for reasonable nitrogen management. Main conclusions were as follows: the amount of nitrogen mineralization in moderate saline soil of the same treatment was significantly lower than that of mild saline soil. In mild saline soil, mineral nitrogen contents added with more inorganic fertilizer were much higher in early growth stage, while a steady increase of mineral nitrogen content was found in soil which combined application of organic and inorganic fertilizer was added during the whole growth period of maize. In moderate saline soil, there was no significant difference in soil mineral nitrogen content in different treatments at the early growth stage, the increase of applied proportion of organic fertilizer was obvious to the improvement of soil mineral nitrogen content in the later stage of crop growth. The corn yield, water and nitrogen use efficiency in moderate saline soil of the same treatment were significantly lower than those in mild saline soil, and the yield was decreased by 30.94%~63.90%（P＜0.05）, respectively. The utilization efficiency of water and nitrogen in mild saline soil was increased at first and then decreased, but in moderate saline soil it was increased gradually with the increase of proportion of organic fertilizer. The water use efficiency of mild and moderate saline soil treated with U1O1 and O1 was the highest, which was 11.84% and 27.68% (P＜0.05) higher than that of U1, respectively. These two combination also obtained the highest yield, corn N uptake, N harvest index, N recovery, N agronomy efficiency and N partial productivity. Based on the changes of corn yield, water and nitrogen use efficiency and variation of soil mineral nitrogen during growth period, the suitable organic and inorganic fertilizer management models of corn in Hetao Irrigation Area were as follows: mild saline soil should be applied with 120kg/hm2 urea+120kg/hm2 organic fertilizer, and moderate saline soil should be applied with 240kg/hm2 organic fertilizer.

Abstract:In order to explore the effect of applying biochar on soil water diffusion and solute dispersion in sloping farmland in black soil area, the biochar effect test was carried out on a typical slope of 15°, 3° and 5° in 2016—2019. The effects of carbon on soil bulk density, porosity, organic matter content, Boltzmann transformation parameter (ξ), unsaturated soil water diffusion rate D(θ), and unsaturated soil hydrodynamic diffusion coefficient Dsh(θ) in the single application of biochar were analyzed. The results showed that the soil bulk density was significantly decreased, and soil porosity and soil organic matter content were significantly increased in the soil within a year after the addition of biochar. And the changing rate of each index was decreased with the increase of slope and the extension of carbonation period. Among the three factors of slope, year and whether to apply biochar, the most significant effects on soil bulk density, porosity, organic matter content were whether or not to apply biochar. Biochar increased the ξ, and the ξ was increased with the slope of soil, and the length of carbon was reduced year by year. From 2016 to 2019, D(θ) and Dsh(θ) were both increased rapidly with the increase of soil water content (θ). When θ≤0.42cm3/cm3, biochar inhibited soil moisture diffusion, and when θ>0.42cm3/cm3, biochar promoted soil water diffusion. When θ≤0.36cm3/cm3, biochar inhibited the dispersion of NaCl solution in the soil, and when θ>0.36cm3/cm3, biochar can promote the dispersion of NaCl solution in the soil. The soil water content in experimental zone was in the range of 0.20~0.35cm3/cm3, thus the biochar had an inhibitory effect on water diffusion and NaCl solution dispersion, and the effect of biochar on water diffusion and solution dispersion was decreased with the increase of slope and prolonged years after charcoal application.

Abstract:PET slices and masterbatch with organic synthetic additives were the main raw materials. Through crystallization drying, melt extrusion casting and longitudinal and transverse stretching, a degradable and recycled polyester agricultural film (DRP film) with high thermal insulation, high transparency, high strength and aging resistance was developed. The radiation transmittance, heat preservation ability, tensile properties, tear resistance, thermal stability and aging resistance of the DRP film were characterized by means of comparative analysis using spectrophotometer, universal testing machine and thermogravimetric analyzer. The results showed that the transmittance of DRP films in photosynthetic effective radiation wave range was 90.73%. The transmittance of ultraviolet radiation B and midinfrared was 0.74% and 14.56%, respectively, which showed that DRP film had a good ability to resist the ultraviolet radiation B and the heat preservation at night. In addition, by comparing the radiation transmittance properties of DRP films aged naturally for about one year over the greenhouse with that of initial DRP films, it was found that DRP films aged naturally declined only 3 percentage points in photosynthetic effective radiation wave range, and it still had good light transmittance. The radiation transmittance of DRP film was decreased only by 4.34 percentage points in 5000~25000 nm after aging, and it still had good heat preservation ability as the film of greenhouse at night. The longitudinal tensile strength of DRP film was 103.21MPa, which could meet the requirements of normal use. The longitudinal trouser tear strength of DRP film was 244.17kN/m, which was 19.49 times of that of PET film. DRP film had three obvious weightlessness phenomena during the temperature rise to 600℃ in thermogravimetric test. The first weightlessness temperature of DRP film was (250±5)℃, and it had better thermal stability. In conclusion, the DRP greenhouse transparent cover material had outstanding advantages in light transmission, heat preservation, mechanical properties and aging resistance.

Abstract:The photosynthetic models now mainly consider the effects of environmental factors on plant photosynthesis. These models can only predict photosynthetic rate of leaves with similar physiological conditions. In order to meet the needs of modeling the models for leaf photosynthetic rate prediction in different growth states, a method for constructing a multienvironmental factors photosynthetic rate prediction model incorporating dark fluorescence parameters Fv/Fm was proposed. Taking eggplant leaves of different growth states as samples, the Fv/Fm were obtained, and the photosynthetic rates were measured at different temperatures, CO2 concentrations and light intensities to construct a set of modeling samples. Then a unified prediction model of photosynthetic rate was established by using genetic support vector regression. The determinant coefficient of the model was 0.8895, and the root mean square error was 3.2679μmol/(m2〖DK〗·s). The results of XOR checkout showed that the accuracy of the model was improved remarkably by fusing the Fv/Fm. The fitting slope between the predicted and measured photosynthetic rates was 0.9046, the intercept was 0.3641, which showed that the model could predict an exact photosynthetic rate of leaves with different physiological conditions by leading in Fv/Fm.

Abstract:High yield and quality of lettuce were objects under the intercropping aeroponics system with cherry radishes. The orthogonal test of three factors and three levels were enforced to reduce nitrate content in edible parts of lettuce under the intercropping aeroponics system. According to a large number of single factor experiments in previous researches, the orthogonal test was utilized to study the influence of intercropping ratio, phased management of nutrient solution concentration and the time of preharvest light supplementation on target plants. The results showed that the optimal combination of factors in the cultivation management mode was as follows: the intercropping ratio of lettuce and cherry radish was 2; the nutrient solution was supplied by 0.5 standard concentration in the early stage and in the week before harvest in stages, and standard concentration in the middle stage; and the time of preharvest light supplementation was 48h. High yield, high quality and low nitrate content in the edible parts were found for lettuce in optimal cultivation management mode, which meant that the optimization was obvious. That’s to say, the cultivation management mode provided theoretical basis and reference for the study of soilless cultivation of high quality leafy vegetables with low nitrate.

Abstract:An air scrubbing system was developed to efficiently treat the exhaust emission from largescale pig house. The system utilized a combined scrubbing system that involved chemical method and waterwashing method. The realtime dynamic environmental data, including pH value, EC value, liquid level and differential pressure were collected. The intelligent control strategy was established via programmable logic controller (PLC) control system to regulate the startup of the washing pump and electron magnetic valve. In this manner, four work links: water supply, acid addition, spraying and waste emission were conducted automatically. At the mean time, the control system utilized MCGS touch screen to establish communication connection with PLC. In particular, the human machine interface was created to realize the monitor of system environmental data, dynamic display of operation process, configure system parameters, system alarm and other functions needed. Therefore, the system achieved the purpose of monitoring and controlling on the whole purification process, as well as satisfied the simple operation of system and visualization of the whole scrubbing process. Moreover, the system can also implement a variety of control modes according to the requirements of efficiency and economy in practical applications. It was found that all control modes were able to inhibit the emission of pig house effectively. The experimental results indicated that the removal rate of ammonia gas can reach 85%. The overall system was entirely well operated and easily controlled, and the economic costs were clearly quantified as well. This gas scrubbing system was successfully applied to a pig breeding farm in Jiangxi Province, which provided significant reference of air scrubbing techniques for livestock operations in practical engineering.

Abstract:Traditional aerobic composting of cow manure is not conducive to seedling raising, and adding conditioner is an important method to improve its capability of nursery. As a byproduct of agricultural and forestry waste pyrolysis industry, wood vinegar was not been effectively used. In order to optimize the pretreatment process of cow manure aerobic compost for seedling substrate, cow dung and wheat straw were used as raw materials and wood vinegar as regulator, and adding 0, 1%, 3% and 5% of wood vinegar to the compost and putting the material into the small test reactor for fermentation. Based on the analysis of the composition of wood vinegar, its effect on the aerobic composting process was studied, and then the compost material was used for seedling test. The results showed that with the increase of the concentration, the content of water, TN, TP, K+ and organic matter degradation rate showed an upward trend, however, the pH value and EC value showed a downward trend. The relative degradation rates of cellulose and hemicellulose can be enhanced by low concentration (1%) of wood vinegar. Cucumber was selected as the test crop, and the compost material was used as substrates for germination and seedling test. The germination index of the composting extracts of all groups were more than 50%, which basically reached the nontoxic requirement of plants. The highest germination index group was 1% wood vinegar group, which was 79.17%, and in the subsequent nursery test, the seedling index (0.0449g) of the 1% wood vinegar treatment group was significantly higher than that of the other groups (P<0.05). The results of this study can provide theoretical basis and reference for optimizing the pretreatment process of cow manure aerobic composting as seedling substrate. 

Abstract:Fe-Ce/dolomite catalyst was prepared by the impregnation method, and the catalyst was characterized by SEM and XRD. The hightemperature water vapor catalytic gasification test was carried out on a selfbuilt fixedbed gasification furnace test station, and the content of the auxiliary agent was studied. The effect of the gasification temperature and other factors on the gasification characteristics of the water vapor of pine rod and effect of number of times of catalyst on deposition of gas component and catalyst were researched. The experimental results showed that the auxiliary Fe and Ce can be well supported on the dolomite, and the catalyst gasification effect of the assistant content of 8% Fe-2% Ce was good. Fixed the catalytic temperature, and the catalyst was used for making the pine wood rod at different temperatures. In the steam gasification test, when the temperature was increased from 750℃ to 950℃, the gas production rate and hydrogen production rate were increased from 1.05m3/kg and 31.67g/kg at 750℃ to 1.56m3/kg and 65.39g/kg at 900℃, respectively. Compared with the gasification test without catalyst, the hydrogen production rate was increased by 0.15m3/kg and 16.27g/kg, and the hydrogen volume fraction was increased from 39.02% to 46.95%, respectively. The third gasification test of the catalyst was carried out at 800℃. The volume fraction of hydrogen was decreased from 40.34% in the first time to 38.97% in the second time and 34.95% in the third time. The amount of carbon deposition was increased from the first time of 21.55mg/g to the third time of 31.61mg/g.

Abstract:At present, the vacuum precooling device has a large volume, high energy consumption, and the water catching capacity of the water trap can not be well adapted to the problem of evaporation of water vapor. In order to solve the above problems, a smallscale wolfberry vacuum precooling device based on brine storage was designed. According to the technical requirements, the mathematical model of vacuum precooling was established. The theoretical analysis of the surface mass transfer resistance layer was carried out. The key parameters of the vacuum pump, vacuum precooling and cooling load, brine storage system and computer detection system were designed and calculated. Finally, a small cooling storage vacuum precooling device for fresh wolfberry with stem was produced. The experimental results showed that the vacuum precooling device can reduce the center temperature of 8.714kg fresh wolfberry to the preservation temperature of 4.0℃ in 879s, and the water loss rate was 5.29% when the water replenishment rate was 4.50%. The water trap of the device was designed to have a water catch rate of 75.00%, and the actual water catch rate was 79.32%. The brine temperature in the brine tank was increased from -20.1℃ to -9.8℃ during the test. The cold storage capacity of the brine in the tank can ensure the smooth completion of the vacuum precooling process. By adjusting the brine pump to change the brine circulation speed, the balance between the catchment of the water trap and the evaporation of water vapor was achieved, which met the design requirements.

Abstract:Aiming to explore the effect of wetthermal characteristics and morphology of hotairflow on the microwave vibrating fluidized bed drying, the drying kinetics，thermal image changes，water distribution，color and microstructure of fresh bitter gourd slices under four microwave-hotairflow drying modes were studied by microwave-hotairflow vibrating dryer. The results showed that the hotairflow temperature had a significant effect on microwave-hotairflow vibrating fluidized bed drying. The drying time of hotairflow drying was slower, and the drying time of microwave drying alone, microwave power 0.6W/g+hotairflow 60℃+ airspeed 3m/s, microwave power 0.6W/g+hotairflow 70℃+ airspeed 6m/s was 56.4%，70.5% and 75.6% shorter than that of the hotairflow drying with hot air 70℃+airspeed 3m/s. The color of dehydrated product by hotairflow was closest to fresh balsam pear slices, the color of dehydrated product by microwave-hotairflow combination drying was better than that of microwave drying alone. The temperature uniformity of microwave-hotairflow combination drying was significantly better than that of microwave drying alone and hotairflow drying alone. The moisture signal was gradually decreased and the main peak was moved to the left under NMR spectrum by four drying modes. The MRI signal showed that hotairflow had a significant effect on the uniformity of water distribution during microwave drying. Scanning electron microscopy observation showed that the hotairflow drying was the most obvious to maintain the cell integrity of dehydrated product, and the cell integrity of microwave-hotairflow drying was better than that of microwave alone. The study provided a theoretical basis for the processing technology selection of dehydrated product.

Abstract:Characteristic Terahertz (THz) region closely related to corn seed aging were screened by using THz time domain spectroscopy technique and moving window correlation coefficient method. There were three different varieties of corn seeds selected and processed by artificial aging for 0d, 1d, 2d, 3d and 4d. The embryos and endosperms of corn seeds samples were isolated and pulverized. THz absorbance spectra (0.2~80cm-1) of the powder samples were collected by THz time domain system and attenuated total reflection (ATR) accessory. The moving window correlation coefficient method was applied to screen the characteristic spectral regions which were sensitive to seed aging. After comparing the parameters of the moving window correlation coefficient, the window width was determined to 10 and threshold value was 0.3. According to the result, the selected characteristic spectral regions showed significant differences among different varieties of samples, which indicated that the seed aging process was greatly affected by the variety. However, there were minor common regions in the same aging stage which were mainly concentrated in 60~80cm-1. It was showed that the similar components were changed at the same time. Due to the selected characteristic spectra of endosperm and embryo at the same aging stage were different, it was showed that the endosperm and embryo had different physiological changes during seed aging process. The experiment result indicated that THz time domain spectroscopy combined with chemometric method can be used to characterize and detect the dynamic changes of corn seed aging rapidly and macroscopically. 

Abstract:Protein content is one of the most important quality indicators of milk. The traditional methods used to measure the protein content of milk have the advantage of high precision, but the measurement procedures are tedious and timeconsuming, and the measurement equipment are expensive. In addition, these methods cannot be used in filed or insuit. Therefore, developing a kind of portable milk protein content detector which is simple in operation and low in cost, and could be used insuit measurement, will be appreciated by milk producers, processers and consumers. Since the values of electric parameters of milk are affected by protein content, a portable protein content detector over the frequency range of 1~100MHz was developed. The hardware of the detector consisted of a STM32 single chip microcomputer, a frequency sweep signal source module, a detection module, a signal processing module, and an input and output modules. The software, developed under the development environment of MDK 5.0 by using C language, realized the functions of initialization, frequency sweep, data sampling, serial port transmission, key processing and result display. Fresh raw milk were used as samples to analyze the relationship between the protein content and the obtained data, i.e., the amplitudes of input and output signals, and the phase difference between the input and output signals. The partial least squares model was established to predict the protein content based on obtained data. The results showed that the model had a determination coefficient of 0.835, the absolute measurement error of -0.11~0.12g/(100g), and the average absolute error of 0.01g/(100g). Moreover, the measurement could be realized in 2 min. The developed detector made the detection of protein content of fresh raw milk realized quickly and effectively.

Abstract:Aiming to clarify the transmission relationship of the crossed friction wheel mechanism and apply it to the motion analysis of the Mecanum wheeled omnidirectional mobile car, the transmission principle was theoretically analyzed through motion analysis and force analysis. The theoretical relationship and the design calculation method of dynamic parameters of a special case of the crossed friction drive about wheel-ground crossed friction wheel drive were analyzed. The method for judging the axial movement direction of the driven transmission member was constructed. The ADAMS was used to simulate the transmission model of crossed friction wheel under different loading conditions. On this basis, the motion principle of the omnidirectional mobile car based on the Mecanum wheel was analyzed by using the mechanism of the crossed friction wheel transmission. The research result showed that the theoretical analysis of the transmission relationship was correct. When the transmission was effective, the angle between the static friction force of the contact point and the axis of the wheel was depended on the applied load value. The static friction of the contact point and the applied load could be adaptively balanced. The relationship between the moving speed of the wheel center and the axial moving speed along the shaft and the driving speed of the supporting shaft was not affected by the external load. These three speeds formed a rightangled triangle relationship, and the two speeds of the friction wheel were the cosine and sine of the driving speed. The transmission relationship between the ground and the small rollers of the Mecanum wheel belonged to the crossed friction wheel drive. It was feasible to analyze the omnidirectional mobile car by using theoretical movement relationship of the crossed friction wheel. It provided an intuitive and concise theoretical method for the analysis of the omnidirectional mobile car based on Mecanum wheel, and also provided a theoretical basis for the application design and analysis of the crossed friction wheel drive. 

Abstract:Aiming to solve the problems of low energy utilization and insufficient cruising range of pure electric tractor, a power supply system of pure electric tractor based on super capacitor and battery composite was proposed. By analyzing the working condition characteristics and power demand of pure electric tractor, the topological structure selection and parameter matching of power supply system were carried out. According to the topology of the composite power system and the operating principle of the battery pack, super capacitor pack and DC/DC, a suitable modeling method was selected to model the battery pack, super capacitor pack and DC/DC by using Simulink, taking the lowest energy consumption of power supply as the optimization objective, the energy control strategy of power supply system of pure electric tractor was optimized by using dynamic programming, and the results of dynamic programming were obtained, and the characteristics of working conditions were analyzed, the energy control strategy of power supply based on rules was summarized, the control strategy was simulated by using Matlab/Simulink model. The results showed that the energy consumption of the control strategy based on dynamic programming was 18% lower than that of the rulebased control strategy, which proved the effectiveness and reliability of the energy control strategy based on dynamic programming in energy saving and consumption reduction.

Abstract:In order to further improve the performance of differential pump, a four blade differential pump driven by noncircular gear with free pitch curve was proposed. The performance calculation model of differential pump driven by noncircular gear with free pitch curve was established. The performance analysis software of differential pump was compiled to analyze the performance of differential pump under different control points, such as displacement, flow and pulsation rate. The results showed that the free pitch curve was better than the optimal Fourier curve. The pitch curve had better local optimization ability, which can effectively improve the maximum modulus of noncircular gear without undercutting and the displacement, reduce the pulsation rate of differential pump, and improve the comprehensive performance of differential pump. Through experimental research, under the same pump size and pipeline environment, the displacement of the differential pump driven by noncircular gear with free pitch curve was increased by 6.6% compared with the optimal Fourier noncircular gear, and the maximum module without undercutting was increased by 18.7%. The bearing capacity of the noncircular gear was effectively improved, and the pulsation rate of the single pump of the differential pump was reduced by 8.3%. It can be seen that the free pitch curve noncircular gear was more conducive to improving the performance of the differential pump.

Abstract:Mining shovel is an important equipment in large open pit mining. In lifting operation, the highquality working device is driven by the lifting motor to lift and shovel into the material to realize excavation. When falling, under the gravity force of the working device, the lifting motor generates electricity. This distributed electric energy is often dissipated in the form of thermal energy through brake resistance, causing great waste of energy. In order to solve the above problems, an innovative driving scheme of hydraulic-electric hybrid shovel hoisting mechanism was proposed. A hydraulic pump/motor was added to the hoisting motor coaxially, and the inlet and outlet of the hydraulic pump/motor were connected with an hydraulic accumulator and tank respectively. When falling, under the action of working device gravity force, the hydraulic pump/motor and lifting motor provided braking torque to control the descending speed. At this time, the hydraulic pump pumped the lowpressure oil in the tank into the accumulator and the gravitational potential energy of the working device was stored in the accumulator; when lifting the working device, the device released highpressure oil, and the hydraulic pump/motor worked together with the lifting motor to lift the working device, so as to reduce the installed power and energy consumption of the lifting motor. In the research, the working principle of the driving scheme of the hydraulic-electric hybrid driving electric shovel hoisting mechanism was introduced; the principle testbed was set up to verify the hydraulic-electric hybrid driving scheme; the new hydraulic-electric combined simulation model of the electric shovel was established, and the hydraulic-electric hybrid electric shovel hoisting system was simulated and analyzed. The results showed that the installed power, the peak power and the energy consumption of the motor can be reduced by adopting this scheme. The method can be widely applied to all kinds of heavy lifting equipment driven by motors.