Abstract:The grain combine harvesters of China generally exist problems such as low reliability, low adaptability, and low intelligence and informationize. The cleaning device is one of the core working components of the combine harvester, and its performance is an important factor that directly affects the performance of the whole machine. How to improve the performance and efficiency of the cleaning device is the difficulty and focus of the development of grain combine harvester at this stage. To this end, the research status of domestic and foreign combine harvesting technology and equipment was reviewed from the aspects of cleaning device structure, airflow field and material movement in the cleaning device and intelligent cleaning device. At present, in the basic structure of the combine harvester cleaning device, research was mostly concentrated on multifan, multilayer vibrating screens, shaking plates, etc. In the aspect of the cleaning device fan structure, the fan performance, efficiency, and airflow uniformity of the air outlet were optimized by optimizing the fan volute, impeller, and multiduct structure. In the aspect of cleaning sieve, the sieve surface structure and motion form of the vibrating screen were studied. In the research of the airflow field, a more complete simulation model can be established, and a more accurate airflow field measuring instrument can be established, so that the internal airflow field distributions of the simulation and experiment for cleaning device were closer to that of the real situation. In the research of material movement, the EDEM software was usually used to simulate the movement of material particles on vibration, which can reflect the movement law of materials to a certain extent, but still cannot reflect the internal material movement of the actual cleaning device. Most of the existing gassolid twophase flow in the cleaning device adopted the CFD-DEM software coupling method, but they all simplified the model as much as possible, which caused the numerical simulation results to be different from the actual test results. Most of the researches on the grain loss monitoring sensor adopted the principle of piezoelectric type, which had the characteristics of simple structure, high resolution and suitable for complex working environment. Modern control theory and method were adopted to make the cleaning loss automatically adapt to the working object and environment. The development trend of the combine harvester cleaning device was proposed: development in the direction of light weight; development in the direction of low vibration and low noise; development in the direction of versatility; development in the direction of intelligence and informationize; acceleration of the development of industry, academia and research; cleaning device design by big data fusion. It had important reference significance for improving the working performance and efficiency of the cleaning device and the combine harvester, and further promoting the comprehensive high quality and high efficiency development of the mechanized harvesting of crops in China, which provided a basis for modern harvesting, intelligent harvesting and accurate harvesting.

Abstract:In order to improve the performance of automatic leveling control system of tractors in hilly and mountainous areas, based on the developed attitude adjustment mechanism of hilly mountain tractors, an automatic leveling control method for adjusting the swing angle of wheels by double closed loop fuzzy PID algorithm was proposed. The state space model of the controlled object was established, and a double closedloop fuzzy PID control algorithm was designed based on the model. The simulation analysis of the automatic leveling control system showed that the double closed loop fuzzy PID control had better performance than the double closed loop PID control, which can effectively reduce the overshoot and leveling time. A large number of dynamic and static tests were carried out. The results showed that the proposed automatic leveling double closedloop fuzzy PID control method had a leveling time of 12.5s on the slope of 15°, the maximum leveling error was less than 0.5°, and there was no overshoot phenomenon. The absolute value of the difference between the left and right rear wheel swing angles was within ±1°; at the same time, driving at a speed of 1.98km/h in a harsh working environment with high and low undulations, the tilt angle of the body can be controlled within ±3°, and the absolute difference of the left and right wheel swing angles was within ±5°. Generally, the control method proposed had better control effect than double closed loop PID control.

Abstract:In order to measure the efficiency parameters in the hulling process of buckwheat huller, an online measuring method based on machine vision to measure the efficiency parameters of buckwheat hulling was presented. The image of the fast sliding buckwheat grains was captured. N(B-R) gray transformation was performed on the captured image of buckwheat grains with a light blue background, then with Otsu algorithm the background was segmented and a binary image of buckwheat grains was generated. A distance image of buckwheat grains was generated by performing Euclidean distance transformation on the binary image, a skeleton image of buckwheat grains was generated by performing thinning operation on that binary image, and then the corresponding pixel points of distance image and skeleton image were multiplied and a distanceskeleton image was generated. Seed points were extracted by performing neighborhood maximum filtering algorithm on the distanceskeleton image, the distance images were marked with seed points, and the touching buckwheat grains were segmented with watershed segmentation algorithm. An interactive labeling method was used to label the unshelled buckwheat, whole buckwheat rice, broken buckwheat rice and wrongly segmented buckwheat grains, and then the labeled buckwheat grains were used to train a BP neural network. In the online experiment, the recognition rates of unshelled buckwheat, whole buckwheat rice and broken buckwheat rice were 99.7%, 97.2% and 92.6% respectively and it took 4.79s to process and recognize an 1824 pixels×1368 pixels image containing 897 seeds. The results showed that the rate of unbroken buckwheat rice can reflect the hulling efficiency of buckwheat huller and the running time met the need of online measurement.

Abstract:The pattern of soil disturbance by tillage tools is intimately linked with soil failure mechanisms and tilth quality, being a basis of tillage system optimization. Insitu videoassisted multiindex measurement is a pathway for the illustration on soil disturbance by tillage tools. The insitu composite tillage test rig was applied for measuring subsoiler performance in paddy soil. Videos from five viewports were taken, and meanwhile, soil microrelief, traction, EDEM simulation, CI of disturbed soil profile and theoretical analysis were also measured to investigate how the chisel blade angle α and tillage depth D affected the pattern of soil disturbance, soil failure and tilth quality. Results showed that three indices can be derived from videorecords, i.e., forward soil failure distance R, soil disturbance width W and lifting height H. All the three indices were significantly correlated with both α and D, and H was increased with α, while decreased with D, indicating that both design parameters and the working parameters of subsoiler can have its influence on soil lifting. R was linearly correlated with forward protruding length of the bent leg beneath soil surface, while W was increased with α. Both soil microrelief and soil disturbance width W reached the peak values at 20cm tillage depth. EDEM simulation provided microscopic illustration on the soil disturbance by the subsoiler, reaffirming the videorecorded evidence of nonbalanced soil failure, lateral compression failure and crescent failure patterns. Correspondence between EDEM simulation and videorecording also approved the scientific validness of the discrete models. EDEM simulation also revealed that stressconcentration region periodically shifted up and down along the bent leg. Downward compression effect also appeared beneath the chisel. The CI contour map of subsoiling trench profile not only affirmed the simulated compressing region, but also revealed the sideway rheological soil displacement and the resulted compact side walls at 30cm tillage depth. The results proved that videoassisted multiindex measurement was an important means for optimized subsoiler design for paddy soil.

Abstract:In order to improve the efficiency and quality of rapeseed seedling transplanting, and reduce planting cost, improve planting efficiency, realize rapeseed seedling highspeed transplanting, a set of transplanting mechanism which suitable for horizontal push seedling transplanting in grooves was designed. In order to analyze and optimize the structural parameters of the mechanism, the mathematical model and kinematics equations of the mechanism were established, and a humancomputer interactive program based on Matlab was prepared. Based on the agronomic requirements of horizontal push seedling transplanting in rapeseed, the relationship between the movement trajectory of planting mechanism and the yield of vertical transplanting of seedlings was established. According to the simulation results, a group of parameters such as length, installation position and initial angle of the mechanism were optimized, and a transplanting test device for rapeseed seedlings was designed and manufactured. The static and dynamic trajectory curves of the transplanting mechanism were tested by sensors, it was proved that the actual motion law of the prototype met the requirements of simulation design, and the mechanism design, mathematical model, software program and relational model were accurate. The laboratory seedling test showed that the pass rate of horizontal push seedling planting was not less than 90%，under the conditions of the transplanting plant distance was 0.2 ~ 0.3m at mechanical driving speed of about 0.4 ~ 0.6m/s, and the frequency of the planting mechanism was between 1Hz and 1.5Hz, the transplanting depth was about 0.04 ~ 0.06m. The experimental results showed that the transplanting of horizontal push seedlings can meet the requirements and high efficiency of the transplanting of rape seedlings, the research result had certain guiding significance for horizontal seedling transplanting.

Abstract:In order to improve the mechanization degree of vegetable plug seedlings pickup, realize the automatic seedlings pickup of vegetable plug seedlings and improve the seedlings pickup efficiency, a kind of pickup mechanism for exploring and pickingpushing vegetable plug seedlings was studied and designed, which can realize the action of picking up and pushing plug seedlings quickly. Big fruit chili plug seedlings were taken as the objects of seedling pickup. The working principle of seedlings pickup mechanism was analyzed, the kinematic model of the mechanism was established, its optimization goal was established, and the visual auxiliary analysis software was developed by using Visual Basic 6.0. the optimum parameters to meet the requirements were optimized and the corresponding theoretical trajectory was formed. The threedimensional model was established, the virtual simulation design of the model was carried out, and the simulation trajectory was obtained. 3D printing technology was used to manufacture the test prototype, and the actual trajectory of the test prototype was extracted by using highspeed photography technology, and the consistency between the actual trajectory and the theoretical trajectory and the simulation trajectory was verified. In order to make the effect of the test prototype consistent with the actual mechanism, the maximum entry force of the actual seedling needle was measured, and the maximum pedestal soil force of the test prototype was calculated by using the principle of similarity theory, and the optimum matrix ratio of the plug soil was 0.4. The seedling pickup test was completed. The success rate of seedlings pickup was 96.87%, which met the requirements of vegetable plug seedlings pickup and verified the correctness and feasibility of the mechanism design.

Abstract:In the process of harvest, spinach plants could be damaged easily by clamping conveyer device. To solve the problem, the rheological property of spinach plants was used to analyze the gripping delivery parameters on the effect of damage to spinach. Firstly, a kind of spinach gripping delivery device was put forward, its working principle and the mechanical structure were expounded, the relationship of floating clamping device with spinach plants was analyzed. Rheological constitutive equation of spinach plants under the action of extrusion was constructed by Burgers viscoelastic model. By the creep test, the constitutive equation coefficients of spinach plant samples were obtained. Without considering elastic deformation and viscoplastic deformation, the constitutive equation of spinach plastic deformation was obtained and the degree of plastic deformation was used to measure spinach mechanical damage. The influence of equivalent modulus of elasticity, transmission speed on plastic deformation was researched. The operation condition of minimum plastic deformation was obtained and it could achieve low damage harvest at this time. Three kinds of transmission speed and three kinds of equivalent modulus of elasticity were selected, and the five groups of parameters were studied. The constitutive equation of clamping force with time under different working parameters was obtained, and the operation condition for minimum plastic deformation could be obtained by the equation. Finally, a gripping delivery test platform was set up, the result of the experiment showed that when the equivalent modulus of elasticity was 2N/mm, the transmission speed was 25mm/s, the success rate of conveying spinach was 93.3% and the injury rate of spinach was 6.7%, the effect of gripping delivery was better. The experiment proved that the rheological properties of the spinach could be used to analyze of the influence of working parameters on the spinach damage feasibility. The research provided the theoretical basis and technical reference for the design of the leafy vegetable low damage mechanical harvest.

Abstract:In order to improve the complicated seedling picking and throwing mechanisms of domestic vegetable transplanter, an airblowing combined with vibration type seedlings unloading mechanism was designed based on a modified seedling tray at first. And the designed mechanism was composed of three main parts which were feeding device, vibrating device and airblowing device and each part was cooperated to complete the automatic picking up and delivering seedings work. After that, the dynamic models of seedling and seedling tray were established during the seedlings unloading process. Through analyzing the models, the frequency of vibration, the amplitude of vibration and the water content rate of substrate were three main influence parameters which had effects on success rate of seedlings unloading. Furthermore, a multiobjective orthogonal test was performed considering the vibrating device and airblowing device comprehensively. The success rate of seedlings unloading and the damage rate of substrate were chosen as the evaluation indexes, meanwhile the water content rate of substrate, the frequency of vibration and the air pressure were selected as the experimental factors. And the results indicated that when the water content rate was 55%, the vibration frequency was 36Hz and the air pressure was 0.45MPa, which were the best combination factors, led to a satisfactory result with 92% of success rate and 3.46% of damage rate. The result was able to provide a reference for automated transplanter.

Abstract:In order to improve the performance of airsuction seeder with corn roller, the structure of airsuction disc of airsuction seeder was improved by using elastic rubber according to the characteristics of corn film planting in northwest arid areas. Three factors affecting seed suction ability were obtained by force analysis of suction process of suction cup, which were the rotation rate of suction cup, negative pressure of suction chamber and suction hole diameter of suction pad of seed metering cup. To obtain better performance parameters of elastic suctionnozzle type corn roller seeder, on the selfmade experimental platform of elastic suctionnozzle type corn roller seeder, and according to the central composite design experimental design principle of response surface methodology, the rotation rate of suction tray, negative pressure of suction chamber, suction hole diameter of suction pad of seeder were taken as factors, and the qualified rate of plant spacing was main target, taking into account the reseeding. The response values of seeding rate and seeding failure rate were obtained. The results of bench experiment were fitted by multivariate regression and variance analysis. The two regression models of plant spacing eligibility rate and replaying rate were reliable. The negative pressure of air suction chamber had a significant effect on plant spacing eligibility rate, and the negative pressure of air suction chamber and the diameter of suction pad suction hole of seed metering tray had a significant effect on replaying rate. The results showed that when the rotation rate of the suction tray was 20r/min, the suction chamber negative pressure was 5kPa and the suction hole diameter of the suction tray was 4mm, the qualified index of grain spacing was 95.54%, the miss sowing index was 0.50%, and the replaying index was 3.96%. .Under the same conditions, the qualified index of grain spacing was 96.3%, the miss sowing index was 13% and the replaying index was 2.4%. The optimization achieved the desired results.

Abstract:In order to explore the adaptability of ground lowcapacity profiling spray technology in tea plantation operation, a tea garden lowcapacity contour spray orbit test system was designed, which was used as a spray carrier. The experimental study on the droplet deposition performance of lowvolume spray on tea garden ground was carried out by orthogonal test method. The structure and control circuit of the spray test system were analyzed. The nozzle installation parameters were determined according to the analytical method. The droplet deposition density and deposition uniformity were taken as the main spray indicators, and the effects of spray height, spray direction, fan speed, nozzle type and canopy gradient on droplet deposition during lowvolume spray of tea tree were investigated. The field experiment results showed that the tea tree canopy gradient had a significant effect on the droplet deposition density, and the number of droplets was decreased from the upper, middle and lower layers of the canopy. The number of droplets in the upper part of the canopy was significantly higher than that in the middle and lower parts, while there was no significant difference in the number of droplets in the middle and lower parts. The spray height was negatively correlated with the number of droplets deposited, and the number of droplets at 30cm was significantly greater than that at 50cm, while there was no significant difference in the number of droplets at 40cm and 30cm and 50cm. The spray direction and the canopy gradient had a significant effect on the uniformity of droplet distribution. When the spraying direction was 45°, the coefficient of variation was 0610, which was significantly greater than the coefficient of variation of 0°, 15°, and 30°, and the uniformity of droplet distribution was the worst. The variation coefficients of 0°, 15° and 30° were not significant. The uniformity of droplet distribution on different canopy gradients was significant. The distribution of droplets in the upper part of the canopy was the most uniform, and the distribution of droplets in the middle of the canopy was the worst. The amount of droplet deposition of the low volume spray was generally small compared with that of conventional sprays. The canopy gradient had a significant effect on the amount of droplet deposition. The average sedimentation volume in the upper canopy was 0.608μL/cm2, which was significantly larger than that in the middle and lower parts, while the difference in droplet deposition between the middle and lower parts was not significant. When the spraying direction was 0°, the mean value of the droplet deposition was the largest, which was significantly larger than that of the 45° direction with the smallest deposition amount. When the tea tree was sprayed at low volume, the average deposition density of each layer of droplets was greater than 26 droplets/cm2, and the coefficient of variation at the top of the canopy was not more than 0.5, which met the requirements of the spraying quality of pesticide sprayers in national standards. The research result provided new methods and new ideas for the reduction of pesticide application in tea tree pest control.

Abstract:Aiming at the current situation that the planning of unmanned aerial vehicle (UAV) spraying has not reached the maximum energy utilization rate, target for the shortest total path, payload and safe operation, a combined algorithm of UAV spraying planning based on energy optimization was researched. Using grid method to divide working area, after getting full coverage, the return points can be distributed rationally and the payloads of sorties by setting up supply points, which reduced energy consumption rate of UAV from route and path and improved operational efficiency. The simulation results of the algorithm by the designed mating software of earth station showed that under the same operating conditions, compared with traditional spraying planning which based on drug or energy exhaustion but had occasional forced landing or crash risk, using the combination algorithms to plan the spraying of UAV can save rate of range planning about 16.25% and that of load planning about 18.92%. From the field contrast test, the algorithmplanned operation saved 2725m returning flying range compared with the nonalgorithmplanned operation. The savings rate of flying range was 23.7%. And it can save load about 1L, which meant that the saving rate of load was 16.7%. In summary, this combinational algorithm can save energy effectively and ensure that only when their energy satisfied the safeguard requirement, UAV would operate, and it furtherly verified the energy saving and security of the algorithm.

Abstract:In order to solve the delay caused by different sampling frequencies of multisensors in position estimation of plant protection unmanned aerial vehicle (UAV), a variable structure linear moving horizon estimator (VSL-MHE) was designed to process delay measurement values. Firstly, the measurement data of multiple sensor was serialized. Then the linear index method was used to determine the coordinates of the zero elements in the arrangement term, and the weighting matrix in the cost function was updated with the coordinates of the zero elements to change the structure of the estimator. Finally, the plant protection UAV position was estimated by VSL-MHE. The accuracy of the position estimation was verified from the actual flight tests. In the indoor experiment, the GPS output was simulated by the output of OptiTrack motion capture system, the frequency could be controlled in the range of 2~20Hz. Through the fixedpoint hover experiment, the positions estimated from VSL-MHE, MHE and the circular iterated extended Kalman filter (CIEKF) were compared with that obtained from OptiTrack, respectively. The maximum positional offset of VSL-MHE was smaller than the positional offset of the CIEKF and MHE. In the outdoor experiment, the range of path planning was set to be 40m×30m, and the maximum positional deviation from the VSL-MHE was less than that estimated from CIEKF and MHE. The experiment results showed that VSL-MHE can effectively reduce the adverse effects on the accuracy of position estimation.

Abstract:In order to improve precision of fertilization and efficiency of water and fertilizer utilization in the field, which can further promote flexible application of irrigation and fertilization technology in the field, the mobile irrigation and fertilization machine of precision fertilizer in the field was designed. Firstly, the mechanical design of mobile walking frame, precision fertilizer dispensing device and the first pivot device of integrated machine was carried out. Secondly, taking wheat as an example, based on the amount of water and fertilizer needed by crops in different growing periods, combined with the realtime measurement of soil moisture information, a threestage automatic fertilization time distribution model and a dynamic calculation method of mother liquor concentration were designed. A mathematical model for dynamic control of mother liquor concentration was established. A PID switching control method with Smith predictor was designed to rapidly stabilize the concentration of mother liquor, and the control method was simulated by Simulink to verify the difference of dissolution time of different types of granular fertilizer. On this basis, the central control system of integrated machine was designed, which integrated the time distribution model of irrigation fertilization and the dynamic control method of mother liquor concentration to realize automatic irrigation fertilization function and accurate control of mother liquor concentration. Finally, the experiment of irrigation and fertilization was carried out in the field environment. The response curve of EC of the injector was measured and analyzed. The results showed that the response curve of EC was changed in three segments, which indicated that integrated machine can carry out automatic operation of field crops according to the designed time distribution model. Because of small error fluctuation, short transition time, steep slope and small overshoot, the EC value of fertilization stage was stable, which indicated that the proposed switching control method can quickly stabilize the concentration of mother liquor for different types of granular fertilizer. The research of this machine was of great significance to the field integration and automatic precision irrigation and fertilization.

Abstract:The pump sump is an important part of pump station. Its flow and hydraulic characteristics have an important impact on the performance of the pump. Poor flow patterns are often accompanied by hydraulic phenomena such as vortices. Vortices in the vicinity of pump intakes influence the pump performance with loss of efficiency and vibration. The vortex may appear in the pump sump, and the vortex is generally divided into free surface vortex and submerged vortex. Compared with most Reynolds averaged Navier-Stokes (RANS) based simulations, large eddy simulation (LES) showed a better prediction for all kinds of vortices on location, shape, size of vortex core, velocity, as well as the turbulence kinetic energy inside vortex core. The LES results agreed with PIV results well. Based on the numerical results, timeaveraged behavior of three typical vortices showed better similarities with reality that there was always a core region surrounding the axis where the azimuthal velocity stopped increasing and decreased to zero as radius went to zero. Besides, isosurface of λ2 was adopted to visualize the vortices. The volume of fluid model (VOF) and LES were used to simulate the vortices in the pump sump. The LES model, including the employed mesh was systematically analyzed and the numerical results were compared with the wellknown published experiment with respect to the mean velocity and vorticity fields. Particular interests were paid to discover evolution of the freesurface and wallattached vortices in term of their temporal and spatial characteristics. The anisotropic turbulence structure around the vortices were revealed as well as the momentum transport. The findings provided a deep insight into the application of LES in pump sump and the underlying mechanism of vortex formation and evolution in the sump.

Abstract:The soil salinity is essential for the morphological development, growth process and final yield of crops in the irrigation area. With present methods, satellite remote sensing though was noninvasive, dynamic, rapid and macroscopic, estimated soil salinity of soil covered by vegetation have less significant effect, yet. In order to improve the estimation effect, soil salinity at different depths at Hetao Irrigation Area was collected. GF-1 image simultaneous was downloaded as the data source. Best subset selection was used to analyze the sensitivity of different bands and spectral indices to soil salinity at different depths. RMSE, R2, AIC and SIC were used to determine the optimal combination mode of the sensitive independent variables number at different depths. Based on these, artificial neural network (ANN), support vector machine (SVM) and quantile regression (QR) were used to construct soil salinity inversion model at such depths as: 0~20cm, 20~40cm, 0~40cm, 40~60cm and 0~60cm before and after best subset selection. The determination coefficient for calibration set before best subset selection (R2c0), determination coefficient for calibration set after best subset selection (R2c1), determination coefficient for verification set before best subset selection (R2v0), determination coefficient for verification set after best subset selection (R2v1), root mean square error for calibration set before best subset selection (RMSEc0), root mean square error for calibration set after best subset selection (RMSEc1), root mean square error for verification set before best subset selection (RMSEv0) and root mean square error for verification set after best subset selection (RMSEv1) were used to evaluate the effects of the models. The results showed that B4, BI, SI1 and SI3 were sensitive variable combinations of soil salinity at depths of 0~20cm and 0~40cm. B4, BI and NDVI were sensitive variable combinations of soil salinity at depths of 20~40cm, 40~60cm and 0~60cm. QR inversion model showed its good performance because of its strong robustness. With R2c1 and R2v1 were both above 04, and RMSEc1 and RMSEv1 were both under 04%; followed by SVM, and ANN was the worst. Compared with other depths, the QR inversion model performed best at depths of 20~40cm, with R2c1 of 0611, R2v1 of 0.671, RMSEc1 of 0.177%, and RMSEv1 of 0.160%. The combination of best subset selection and QR method in the modeling analysis of soil salinity provided a new approach to optimize the satellite multispectral model and quickly measure the soil salinity. The research result provided a reference for the widescale soil salinity monitoring of soil covered by vegetation.

Abstract:The effect of heavy metal copper stress on maize leaves reflectance is weak, hidden and difficult to be detected. To analyze the spectral response of maize leaves to copper stress and discriminate the stress degree on maize plant, the pot experiment with 11 copper stress gradients was set at ground laboratory, the maize leaves reflectance and chlorophyll content were obtained at seedling stage, jointing stage and heading stage. The copper content in leaves was also gotten at heading stage. At 480~670nm and 670~750nm, the spectra simulated under the conditions of normal growth, low concentration stress and high concentration stress were constructed respectively. The mechanism of using the first three harmonic amplitudes C1, C2 and C3 to detect the weak spectral distortion in 〖JP2〗maize leaves reflectance under copper stress was analyzed. The harmonic analysis was carried out in two wavelength ranges of 480~〖JP〗670nm and 670~750nm at seedling stage, jointing stage and heading stage, and the rule between the amplitudes C1, C2 and C3 and the copper stress gradient was also analyzed. The results showed that at the seedling stage, in the gradient range of Cu(100) to Cu(1200), with the increase of copper stress gradient, the harmonic amplitude C1 of old leaves reflectance of 480~670nm and 670~750nm was increased, and in the gradient range of Cu(100) to Cu(1200), the harmonic amplitude C1 could be used to distinguish the degree of copper stress on maize plant. At heading stage, from Cu(50) to Cu(1200), except for Cu(1000) gradient, the harmonic amplitude C1 of 480~670nm was increased with copper stress gradient. At jointing stage, for the bands of 480~670nm and 670~750nm, the variation of the harmonic amplitudes C1, C2 and C3 was not obvious in all stress gradients. The seedling stage and heading stage were the best growth stages for monitoring copper stress on maize plants by harmonic amplitude characteristics. The method proposed was designed and tested at leaf scale, and further study were also needed to evaluate its potential at canopy scale. The method proposed provided a potential basis for other applications by using airborne and satellite remote sensing data.

Abstract:Rapid, nondestructive and accurate monitoring of crop biomass is of great significance for crop productivity estimation and intelligent management. In order to explore the feasibility of monitoring crop biomass with light detection and ranging (LiDAR), LiDAR point cloud height metrics and aboveground biomass were obtained from field trials at key growth stages of wheat. Then based on the power function regression and support vector regression, the tenfold crossvalidation method was used to pick features and construct models, and the optimal wheat aboveground biomass monitoring models for whole growth period were selected respectively. Finally, the prediction abilities of the two models were tested and compared on the test set. The results showed that the support vector regression model constructed by the H95 and growth period provided the highest accuracy with an R2 being as high as 0.814 on training set, and its test results were with R2 of 0.821, RMSE of 1.730t/hm2, and RRMSE of 32.77%, which indicated that the model possessed good accuracy and adaptability. The power function regression model constructed by Hmean provided an R2 of 0809, and its test results were with R2 of 0.815, RMSE of 1.760t/hm2, and RRMSE of 33.33%, which also indicated that the model possessed good accuracy and adaptability. Estimation of wheat biomass by a height metric had inherent limitations, and the two models were more suitable for monitoring the aboveground biomass of wheat values less than 10t/hm2. On the whole sample set with aboveground biomass exceeding 10t/hm2, 95% of the predicted values of the models were underestimated and RMSE was increased exponentially. The feature of growth period was helpful to improve the prediction accuracy of the monitoring model.

Abstract:The visual odometer technology was used to restore the posture of the continuous photographic sequences. The sampleplot survey system was constructed based on the images of the restored posture. The system can estimate the position and DBH of the sample trees in the sampleplot by recovering the image posture scale, defining the plot coordinate system, and sample tree marking. Totally 12 circular sample plots with radius of 7.5m were continuously photographed to obtain the image sequence. And then the obtained image sequence was processed with the constructed sample plot survey system to measure the position and DBH of the sample trees. The results showed that the deviations of estimated values of sample tree position of the plots in the xaxis and yaxis directions were 0.04m and -0.03m, respectively, and the root mean square error (RMSE) was 0.21m and 0.17m, respectively. The BIAS and RMSE of the estimated DBH were 0.09cm (0.51%) and 0.88cm (5.03%), respectively. The results showed that the visual odometer technology had a great potential to restore the image posture and to use the nonpoint cloud method to estimate the tree position and the breast diameter from the picture by plot survey method.

Abstract:For the weak points of citrus Huanglongbing (HLB) heat treatment by hot air, such as high energy consumption, slow heat transfer, and heavy heating equipment, far infrared heat treatment method for citrus HLB was put forward. An experimental platform of HLB far infrared heat treatment was set up, which consisted of heat treatment enclosure, far infrared lamp groups, a paperless recorder, a 12 channels temperature recorder and some temperature sensors, to study the influence of the far infrared lamp groups quantity, the power of far infrared lamp, the heating time, position of the far infrared lamps on the temperature field distribution of far infrared heat treatment. The results showed that the quantity of far infrared lamp groups, the power of single far infrared lamp and the heating time had significant effect on the temperature field distribution of leaves and branches, the distance between the far infrared lamp groups and the top of the stent had significant effect on the temperature field distribution of leaves. The factors that affecting the temperature field distribution were optimized. The optimum parameters were as follows: the quantity of far infrared lamp groups was 3, the power of single far infrared lamp was 1kW, the heating time was 3min, and the distance between far infrared light and the top of the bracket was 10cm. Under the optimal parameters, the average temperature of leaves was 58.1℃, the average temperature of branches was 43.1℃, and the average temperature of the whole treatment enclosure was 52.3℃. Under the parameters the effectiveness of infrared heat treatment on the control of citrus HLB was proved by experiments, the average reduction rate of bacteria concentration after treatment was 34.4%. The results provided a reference for the optimization design of largescale HLB infrared heat treatment equipment.

Abstract:Construction of 3D model of tree is a longterm research hotspot in botany, computer graphics, and architecture. And tree canopy branch reconstruction is an important component in the canopy dynamics analysis. The emergence of terrestrial laser scanners has accelerated this reconstruction process. To quickly reconstruct the canopy branch model, it is necessary to delete a large number of nonbranched interference point clouds. Taking the canopy of apple tree in the maturity growth stage as the research object, a method of colorbased sampling apple tree canopy trunk point cloud extraction was proposed. Firstly, the apple tree canopy color point cloud acquisition method was proposed. Trimble TX8 and coaxial panoramic camera were selected as the data acquisition device to acquire the apple canopy color point cloud data. Point clouds and color panoramic photos were matched in Realworks software, and color point clouds were get. Then, the color information R, G and B in the panoramic image was extracted. The adaptive segmentation threshold was established according to the distribution rules of R, G and B in the panoramic image branch area. Color point cloud data of the nonbranch part in the canopy was deleted according to the threshold. Finally, the 3D branch model was reconstructed in the Geomgic software. The process was followed by a series of operations, such as wrap, manifold creation, polygon editing, hole filling and smoothing. The experimental results of the apple tree branch extraction point cloud data showed that the point cloud deletion rate of this method was 75.74%. Compared with the artificial branch point cloud data extraction, the side branch accuracy rate was 93.34%, and the efficiency was improved by more than 200 times, shortening the threedimensional reconstruction time of canopy branches. In this way, the results of this study can provide a basis for studying the canopy structure analysis and the establishment of the branching dynamics model of the leafy apple tree.

Abstract:The morphological traits are important to investigate the state of plant. Measuring the morphological traits periodically during plant growing and fitting the growth model can be helpful to monitor the state and get dynamic growth rule of the plant. And growth model’s visualization can be more directly to show the dynamic changes and predict the plant growth tendency. To speed up and promote the normalization of the measurement of morphological phenotypes, using Arabidopsis thaliana for example, a lowcost machine vision system was designed which can be used to measure the morphological phenotypes of Arabidopsis thaliana during its growth process. With the growth data getting from the system, the plant growth equations and visualization model can be built. A platform was set which consisted of two main parts, fixed part for loading plant and moving part for carrying visible camera, to make sure that the plant would not shake so that can get clearer image sequences. Structure from motion (SfM) was used to get the 3D point cloud from the image sequence. Because of the weakness of SfM, which made the coordinate system generated each time different, a preprocessing algorithm to point cloud based on color panels board was designed to standardize every plant 3D point cloud model’s coordinate system as one. Under the stage for loading plant of the platform’s fixed part, a color panels board was set, which was a black board on which two red panels consisted of two linestyle and a rectanglestyle and one blue panel, and would be transformed to a part of the 3D point cloud. After filtering procedures, the areaofinterest of Arabidopsis thaliana was extracted from the original point cloud. To test the reliability of the color panels board, a 3mm×3mm blue square was fixed on the platform for a repeat trails. Firstly, three kinds of board were used, on which red panels were only linestyle, only rectanglestyle and both of them respectively, for three testing groups. Each testing group had 30 3D point cloud models from the same 10 plants and each plant was collected from three different camera perspectives. Secondly, the method to standardize every 3D point cloud model’s coordinate system was used. Then the centroid coordinate of 3mm×3mm blue square’s point clouds on each model was got, and the Euclidean distance between the centroids in each testing group was calculated. Throughout the value of contrast test, the mean absolute percentage error of leaf width, leaf length, main stem’s length, leaf area and angle between leaves were 9.83%, 10.10%, 1.07%, 4.09% and 4.37%, respectively. A timeseries morphological phenotyping data of three Arabidopsis thaliana samples were collected and used to fit a mathematical model. After that, the model was visualized on Lstudio with L-system. 

Abstract:The architecture of rice roots is the spatial configuration of its roots, which shows a high diversity. To explore the architecture and distribution characteristics of rice roots，hydroponics method experiments were conducted to measure three dimensional spatial coordinates and morphological parameters of rice roots at different growth stages, which quantified the structure of rice roots with high accuracy. After analyzing the experimental data， the initial position of the root node, growth direction of branches and the root growth function were determined. Three dimensional growth modeling of rice roots based on differential L-system was proposed to describe its growth rule by analyzing the topological structure and quantifying their biological characteristics, and the output accuracy of the model was tested. Visual C++ and OpenGL standard graphics library were used to implement the threedimensional visualization simulation system for rice root growth，and the dynamic growth process of rice roots was visually reproduced. Analysis results indicated that the average simulated fitness of the total root length, surface area and volume were about 96.82%, 95.86% and 93.96%, respectively. Therefore, the model can express the morphological characteristics and growth rules of rice roots at different growth stages, and the results may form a base for forthcoming study on the relationship between morphological structure changes of rice roots at different growth stages and their physiological and ecological factors.

Abstract:The rational polyculture and close cultivation of multispecies freshwater fish have great practical significance in aquaculture. Aiming to identify the mixed proportions of freshwater fish, bream fish and crucian carp were taken as the research object. The passive acoustic signals of different proportions of freshwater fish were collected by hydrophone. The butter function was used for signal preprocessing. Then shorttime average energy, shorttime average zerocrossing rate, four layer wavelet packet decomposition frequency band energy, average Mel cepstrum coefficient, main peak frequency and principal peaks based on power spectrum were extracted to construct eigenvectors. The support vector machine model based on principal component analysis was used to realize the mixed proportion identification. The significant differences among the acoustic signals of freshwater fish with different mixed proportions were analyzed, and the influences of the number of principal component on the recognition rate of the model were studied. The results showed that the average Mel cepstrum coefficient had the most significant effect on the mixed proportions recognition of freshwater fish, and the effect of proportional recognition was the best by selecting the first 19 principal components. The average accuracy rate was 96.43% and Kappa coefficient was 0.96.

Abstract:In broiler production, the temperature under the wing is an important indicator of animal health and welfare condition. Body temperature detection method of broiler based on infrared thermography was proposed to achieve measurement of broiler body temperature accurately and rapidly. The detected region of interest (ROI) model of broiler head and leg, based on a convolutional neural network, was developed to extract the maximum temperature of its head and leg. Besides, combined with ambient temperature, humidity and light intensity, two different broiler wing temperature inversion models were proposed by multiple linear regression and back propagation （BP）neural networks, respectively. And the experimental results showed that, based on the deep convolutional neural network, the ROI detected model achieved a precision and recall rate of 96.77% and 100% on the test dataset, respectively. What’s more, the temperature inversion models achieved an average relative error of 0.33% with multiple linear regression, while BP neural network was 0.29%. Deep learning method was used to obtain the ROI temperature, which was superior to the image processing method, high in efficiency and high in generalization ability. BP neural network model error was less than the error of multiple linear regression network model. Therefore, BP neural network can be applied as a temperature inversion model of broiler wings. BP neural network had the ability of selflearning and selfadaptation, and its generalization ability was strong. Applying it to the inversion of temperature under the wing can improve the accuracy and adaptability of the model. This model provided reliable technical support for realtime monitoring of broiler body temperature.

Abstract:The wireless sensor network technology provides efficient and reliable technical means for farmland information monitoring in recent years. WSN is a selforganizing network composed of a large number of sensor nodes with sensing and computing capabilities. WSN can detect abnormal events in farmland information, such as fire, environmental pollution, etc. Considering the characteristics of the large monitoring area, limited energy of monitoring nodes and occasional abnormal events, an anomaly event detection for farmland information monitoring based on improved CoSaMP was presented. In the classical CoSaMP algorithm, the choice of similar atom was difficult, and the sparse K required was known. For distinguishing effectively, the correlation between the atoms, the Dice coefficients were used to choose the optimal atom. The PSNR had the similar fluctuation with the match signal residual, which can be used to adjust the number of iterations dynamically. Firstly, the article modeled the farmland sensor network, and optimized the position parameters of the sensor. Then the CoSaMP algorithm was improved, the quality of signal reconstruction was improved by Dice parameters, and the recognition rate of the algorithm was improved by PSNR algorithm. Finally, the algorithm was simulated by Matlab. The simulation results indicated that the algorithms abnormal event detection success rate was 20% higher than that of the existing algorithm, the network energy consumption was reduced by 15%, and the time of detecting was reduced by 50%. At the same time, it provided a theoretical basis for the intelligent monitoring of farmland information and had higher practical application value.

Abstract:In order to obtain the information of field environment and soil in a quicker and more convenient way, a type of information collection vehicle based on TCP was designed. The overall design of the vehicle system included power system, motion control system, power supply system, wireless image transmission system and sensor detection system. The corresponding data can be obtained by sensor detection system, which included DHT11 temperature and humidity sensor, photoresistor sensor, DS-CO2-20 carbon dioxide sensor and hot wire wind speed sensor. It was proposed to use the 5DOF manipulator and the selfmade soil sensor bit to obtain the soil temperature and humidity information. The composition and operation of the manipulator were analyzed and simulated by Matlab simulation. According to the results of the performance tests carried out on the collection vehicle in the wheat field, it can be seen that the overall design of the collection vehicle was reasonable. The vehicle had strong passability. The maximum tilt angle was up to 30° and the maximum remote control distance was 45m. Precise pictures can be secured as well. Compared with those measured by common highprecision instruments, the data collected by the sensor integrated in the vehicle met the needs of experiment, as the correlation coefficient between the temperature, humidity, light intensity, CO2 concentration, wind speed, soil temperature and soil moisture measured by the agricultural information collection vehicle and the highprecision instruments was greater than 0.90. The collection vehicle can realize the function of obtaining field data in a large range at a fixed time, and replace and supplement the traditional Internet of things system.

Abstract:As a typical aerial robot, quadrotor has major advantages when used for aerial photography, environmental monitoring and surveillance in dangerous and complex environments. The robust control problem in attitude tracking of an unmanned aerial vehicle quadrotor is a challenging task due to strong parametric uncertainties, large nonlinearities, and high couplings in flight dynamics. Towards the attitude control of a quadrotor aircraft under lumped disturbances, a fastcontinuous nonsingular terminal sliding mode controller based on linear extended state observer was proposed. In this control structure, a linear extended state observer was used to estimate, and compensate the lumped disturbances, which can enhance the stability of the controller. With its finite time convergence characteristic the nonsingular terminal sliding mode was employed to design the control law, which can increase the convergence speed. Stability of the controller was proved through Lyapunov function. To enhance the control performance, a salp swarm algorithm was introduced to adjust the control parameters of the proposed controller. Furthermore, a 1dimension positive cloud model and an adaptive operator were applied to overcome the defects of the salp swarm algorithm. Lastly, some simulation and experiments were conducted to test the efficiency and application of the controller. The results showed that the proposed controller had higher tracking accuracy, stronger antidisturbance ability and faster response speed.

Abstract:The object was to explore the reasonable technical index of subsoiling for the annual double cropping of winter wheatsummer maize in meadow soil of northern Henan Province. In 2017—2018，based on the data of field experiment，the subsoiling was conducted before sowing winter wheat in Huojia County of Henan Province. The experimental design used two kinds of subsoiling machine（T，traditional subsoiling machine；A，subsoiling + fertilization integrated machine）and three depths （D1，30cm；D2，35cm and D3，40cm）were set on the traditional subsoiling machine and a deep depth（D2，35cm）on subsoiling + fertilizer integrated machine，meanwhile，the conventional rotary tillage（CK，average tillage depth of 15cm）was used as a control. The variations of crop yield and water use efficiency of each subsoiling treatment were analyzed by measuring soil bulk density，soil water content and crop yield and yield traits. The result showed that the subsoiling method could change the soil bulk density，and the soil bulk density in 10～30cm soil layer was significantly reduced（p＜0.05）. Subsoiling treatments also had a significant impact on soil water content，which could increase the water storage capacity in field（p＜0.05）. During the annual twoseason crops，the water storage capacity of soil in 0～100cm soil layer in descending order was TD2, TD1, TD3, AD2 and CK. Compared with the water storage capacity of rotary tillage，that of the subsoiling treatments was increased significantly by 34.9%，28.9%，28.5% and 27.0%（p＜0.05），respectively. Subsoiling treatments also could significantly increase the number of spikes and kernels of crops，and increase the yield of crops（p＜0.05）. The yield of subsoiling treatments were averagely increased by 8.3% in twoseason crops compared with the rotary tillage，and the effect of increasing yield of winter wheat was greater than that of summer maize. At the same time，subsoiling could also greatly improve the water use efficiency（WUE）of the crops in the winter wheatsummer maize multiple cropping system，and significantly reduce water consumption and water consumption intensity of crops（p＜0.05）. The WUE of subsoiling treatments was averagely increased by 12.4% compared with that of the rotary tillage，among which AD2 had the best effect. Therefore，subsoiling before the sowing of winter wheat was conducive to the rational construction of soil tillage layer， which improved crop yield and water use efficiency. It had a high promotion value for the dry farming wheatmaize multiple cropping system of northern Henan Province. 

Abstract:The ecostoichiometry of soil nutrients has been successfully used in indicating soil quality and revealing the circulation and balance mechanism, and the information about ecostoichiometry of soil carbon, nitrogen and phosphorus can help to conduct soil nutrient management. However, the soil stoichiometry characteristics in dry farming region are poorly documented. To explore the spatial distributions of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) and ecological stoichiometric characteristics of soil C, N and P in dry farming region of Northeast China,totally 132 topsoil samples (0~20cm) were collected in 2017, and SOC, TN, TP and other properties were analyzed in all samples. The spatial variability of ecostoichiometry of soil C, N and P and its influencing factors were analyzed by geostatistics and redundant analysis. The results showed that the mean content of SOC, TN and TP in the study area was 16.79g/kg, 1.43g/kg and 0.77g/kg, respectively; and soil C/N, C/P, N/P ratios were 11.45, 22.82 and 2.03, respectively. Correlation analysis of soil C, N and P showed that significant correlations were existed among C, N, and P (P<0.05). Soil C/N, C/P, N/P ratios were lower than their average value on a national scale. The distribution of soil SOC, TN and TP were increasing from southwest to northeast, with the high value areas mainly distributed in the northern part of the dry farming region of Heilongjiang Province, and the low value areas were in the dry farming region of Jilin and Liaoning Provinces. The high value areas of soil C/N and C/P were mainly distributed in the dry farming region of Heilongjiang Province, the low value region was located in the dry farming area of Jilin and Liaoning Provinces, and the spatial variation of N/P was small in the study area. The ecostoichiometric characteristics of soil C, N and P in the study area were affected by tillage and fertilization, environmental factors and soil properties. Intensity of chemical fertilizers application and land use was an important human factor affecting the ecostoichiometric of soil C, N and P. RDA indicated that soil bulk density and water content were the main soil physical and chemical factors affecting the ecostoichiometric characteristics of soil C, N and P in dry farming region of Northeast China.

Abstract:Aiming to explore the application effect and comprehensive effects of adding biochar for many years in the black soil region of Northeast China, find the best carbon application amount and application period, and provide scientific theoretical guidance for the efficient use of black soil resources and the sustainable development of water resources. In 2015, the research on the best application mode of biochar was carried out at Hongxing Farm in Bei`an City, Heilongjiang Province. Five treatments, including Y0 (0t/hm2), Y25 (25t/hm2), Y50 (50t/hm2), Y75 (75t/hm2) and Y100 (100t/hm2) were set according to the amount of biochar applied, and each treatment was repeated twice, and continuous application for four years (2015—2018), indicators of soil physical and chemical properties, soil and water conservation effects, and watersaving yield increase were observed. A projection model optimized by genetic algorithm was established to comprehensively evaluate the index. The results showed that with the increase of biochar application and application time, the soil bulk density showed a decreasing trend, soil pH and soil C/N showed an upward trend, and the larger the cumulative amount of biochar applied was, the more obvious the trend was. The field water holding capacity under the treatment of Y25 and Y50 showed an increasing trend with the increase of the application period. The Y75 treatment showed a trend of increasing first and then decreasing. The field water holding capacity under Y100 treatment showed a downward trend year by year, and the field water holding capacity under Y25 treatment in 2018 was 3733%, the runoff coefficient and soil erosion amount were both decreased first and then increased. The effect of 50t/hm2 biochar on reducing runoff and resisting erosion were the best. The yield of corn with 25t/hm2 biochar applied continuously for four years was the highest in all treatments, which was 10350kg/hm2. Through the comprehensive evaluation model, the best biochar application mode of 3263t/hm2 biochar applied to the northeast black soil area was obtained for three consecutive years. The results of this study can provide a theoretical basis for biochar to improve soil in black soil areas.

Abstract:To explore the effects of digestate application on tomato growth and soil environment during the whole growing period of crop, the influences of digestate application ratio and irrigation amounts on tomato agronomic characteristics, quality, yield, soil physical, chemical environment and biological characteristics were systematically studied. The results showed that the plant height, stem diameter and leaf area of T3 treatment (digestate ratio was 1∶4, and croppan coefficient (Kc) was 10) were the greatest, which were 24.11%, 15.59% and 33.92% higher than those of treatment C0 irrigated with water only, respectively. The application of digestate can increase the yield, quality and taste of tomato, in which the treatment of T2 (digestate ratio was 1∶4, and Kc was 0.8) obtained the highest vitamin C and total soluble sugar content. Meanwhile, digestate application can decrease the soil bulk density and pH value, and subsequently increase the soil total porosity and saturated hydraulic conductivity. The content of soil organic matter was firstly increased and then decreased with the increase of soil depth in treatments applied with digestate. Furthermore, the application of digestate can also increase the number of bacteria, fungi and actinomycetes in each growth period of tomato, in which the quantity of soil bacteria and fungi presented an increase trend from seedling stage to fruit swelling stage, where they reached the peak value and then decreased, while the peak value of actinomycetes quantities appeared at fruit ripening stage. The activities of catalase, invertase and urease in the soil of tomato root zone presented the trend of increase continuously, first increase and then decrease, and first decrease and then increase during the whole growth period, and the peak value of them appeared at fruit ripening stage, fruit enlargement stage, flowering and fruiting stage, respectively. T2 treatment was more conducive to tomato growth when the agronomic traits, quality and yield, and soil biological characteristics of tomato were comprehensively analyzed.

Abstract:In order to discuss the feasibility of DSSAT model in the optimization of irrigation schedule for winter wheat in different hydrological years, the corresponding design values of precipitation experience frequency of 25%, 50% and 75% were obtained by using the precipitation data of the growth period of winter wheat from 1985 to 2015 in Lianshui Water Conservancy Research Institute. After that the years from 2001 to 2016 in Huaian Station with close corresponding precipitation of three kinds of empirical frequencies were taken as the representative years, and that was 2007—2008 (wet year), 2006—2007 (normal year) and 2011—2012 (dry year). Fifteen irrigation schedules（T1～T15） were drawn up through different combinations of growth stages and irrigation times, and the irrigation schedules were simulated in three hydrological years by using the DSSAT model after the parameter estimation and verification. The results showed that after calibrated, the genetic coefficients of winter wheat could accurately reflect the main genetic characteristics. Considering the yield, irrigation water capacity and the water use efficiency of winter wheat as a whole, it was advisable to select the irrigation schedule T3 from 2007 to 2008 (wet year), from 2006 to 2007 (normal year), and from 2011 to 2012 (dry year). The schedule T3 was irrigated with 50mm in the regreening period. The irrigation time of wintering, regreening and jointing periods were on December 25, February 20 and March 30, respectively. Under BCC-CSM1.1 climate model, RCP45 and RCP85 were considered to simulate the water and yield effect of winter wheat in 2030—2095 years, and then it was found that when the initial soil moisture content was 60% and 80% of the field capacity, T3 and T6 both had certain feasibility compared with the rainfed conditions.

Abstract:In order to reveal the influence of biochar on soil thermal properties, the farmland soils with different biochar contents were studied in northern cold regions. Soil moisture levels were set at 0%, 8%, 16%, 24%, 32% and 40%, respectively. The variation characteristics of soil thermal conductivity, thermal diffusivity and thermal capacity within the temperature range of 15~-15℃ were measured by ISOMET2114, and the response mechanism of soil thermal characteristic parameters to soil hydrothermal regime was investigated with different biochar contents. Results showed that with the increase of soil moisture, the soil thermal properties had increasing trend while freezing and nonfreezing. Under the condition of 3℃ and biochar content of 0t/hm2, the soil thermal conductivity was increased by 0.1414W/(m·K) and 0.5805W/(m·K), respectively, with the soil moisture content at 24% and 32%, compared with that at 16%. With the increase of biochar, the soil thermal conductivity and thermal diffusivity were decreased, and the thermal capacity was decreased while nonfreezing and increased while freezing. Under the condition of -3℃ and moisture content of 32%, the soil thermal capacity was increased by 0.16J/(cm3·K) and 0.20J/(cm3·K), respectively, with the biochar content of 4t/hm2 and 6t/hm2, compared with that of 0t/hm2. There was a logarithmic relationship between soil thermal conductivity and moisture content, a linear relationship between thermal capacity and moisture content, and a quadratic relationship between thermal diffusivity and moisture content. The effects of biochar on thermal properties of frozen and nonfrozen soils were studied with different soil moisture contents, and the influence of biochar on the thermal properties of frozen soils was firstly analyzed using freezing characteristic curve, which provided theoretical basis for accurately describing the soil thermal condition and applying biochar to improve the soil in northern cold region.

Abstract:Taking super rice as test material, the randomized block design method and barrel experiment were conducted to investigate the effects of four treatments with migration of total phosphorus (TP) in underground drainage and soil leakage loss risks and movement of phosphorus and rice yield. Four treatments were：frequent shallow irrigation (FSI), controlled irrigation (CI) wetshallow irrigation (WSI) and drought planting with straw mulching (DPS). The results showed that compared with FSI and WSI, CI and DPS could significantly reduce irrigation amount and irrigation frequency, the concentration of TP in underground drainage and underground drainage, and effectively promote water saving and emission reduction. Under different irrigation and drainage modes, there were many fluctuations in the whole growth period, and the maximum concentration of TP in underground drainage was 0.450mg/L. The TP concentration in soil seepage at different depths was different in different irrigation and drainage modes. Except for the late tillering period, the TP concentration was the highest on the surface and decreased with the increase of soil profile depth. The TP concentration of soil seepage in WSI and DPS was higher than that in FSI and CI. Compared with the FSI, the yield of CI was increased by 10.45% and the DPS was decreased by 14.69%. The productivity of irrigation water in two years of CI and DPS was significantly higher than that of WSI and FSI. Comprehensively considering the irrigation and drainage, irrigation frequency and phosphorus loss, yield and irrigation water productivity, CI was the best mode for water saving, labor saving, emission reduction and high yield.

Abstract:In view of the low mechanical strength and easy breakage of calcined dolomite when it is used as a biomass pyrolysis catalyst, one preparation method of porous ceramic balls with dolomite and quartz sand as main aggregate was proposed. The porous ceramic balls with high mechanical strength were impregnated with Al2(SO4)3 solutions (0.3mol/L, 0.5mol/L and 1.0mol/L) at 25℃ for 6 h after firing. The load of Al2O3 on dolomite base porous ceramic balls was increased with the increase of Al2(SO4)3 solution concentration. In horizontal tube furnace, the dolomite base porous ceramic balls supported Al2O3 were used as catalyst to carry out fast pyrolysis experiment of corn straw powder. The results showed that the yield of the biooil was increased firstly and then decreased with the increase of relative mass content of dolomite, while the yield of biochar was decreased firstly and then increased when the proportion of dolomite to quartz sand was 30∶70, 40∶60, 45∶55 and 50∶50, respectively. The yield of biooil reached the highest production rate of 3685% and the yield of biochar reached the lowest production rate of 25.11% when the proportion of dolomite to quartz sand was 40∶60. With the increase of Al2(SO4)3 solution concentration, the yield of biooil was decreased and that of biochar was decreased firstly and then increased. Compared with the untreated Al2(SO4)3 solution, the yield of biooil was decreased by 10.69%, 15.33% and 21.55%, respectively. The relative content of alcohols in the biooil was increased slightly and that of ketones, acids, aldehydes was decreased gradually. However, compared with those without catalyst and Al2(SO4)3 solution, the yield of phenols was increased significantly, indicating that the presence of Al2O3 was beneficial to the production of phenols. The main components of noncondensable pyrolysis biogas were CO, CO2, CH4 and H2, among which CO2 had the high volume fraction, accounting for about 63%. The volume fraction of CO was about 32%. The volume fraction of CO2, CH4 and H2 was increased and that of CO was decreased when the porous ceramic balls loading dolomite were used as catalysts. The experimental results would provide a reference for obtaining high valueadded chemicals from agricultural biomass.

Abstract:To accurately detect the content of major metal elements in agribiochar using laser induced breakdown spectroscopy (LIBS) and improve its poor detection sensitivity, high temperature treatment was proposed to remove the effects of moisture, fixed carbon and organic matrix. Primarily, totally 66 representative agribiochar samples with Aad content ranging from 28% to 42% were collected and divided using multiple Aadpartition intervals (14%, 7%, 3.5% and 2%). Moreover, when the interval value was set to be 7%, the Aadpartition of the collected samples was divided into 28%~35% (38 samples) and 35%~42% (28 samples). And the corresponding determinant coefficient between raw samples and treated samples was higher than 0.96. Thus, it was possible to develop a serial Aadpartition calibration model using spectral information of treated samples and chemical information of raw samples. In comparison with the modeling effects of raw samples, the partial least squares regression (PLSR) models developed by treated samples had lower values of relative standard deviation of crossvalidation set. The pairwise T test of its prediction set showed that there was no significant difference between the measurement of LIBS and inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the LIBS can be used to simultaneous, accurate and quantitative analysis of major metal elements in agribiochar based on the high temperature treatment and serial Aadpartition calibration model.

Abstract:In the study of gelatinization characteristics and kinetics of starchy raw materials, hydrothermal treatment with controllable parameters was needed, but the effect of heating methods on homogenization of temperature distribution of samples was usually neglected. A device and method for clamping and heating feed samples with cast aluminium plates were presented. The moistureadjusted feed samples were sealed in zip lock bags and clamped in a set of parallel temperaturecontrolled cast aluminium plates for heating treatment. Based on onedimensional heat conduction equation, the temperature curves from room temperature to setting temperature were obtained by using the finite difference method of Matlab, and the temperature homogenization of feed samples during heating process was evaluated. The results showed that the device could achieve full homogenization of samples temperature distribution in a short time, and the time scale for achieving homogeneous temperature distribution of samples was much smaller than the gelatinization time scale, which indicated that the time for heat treatment of samples could be controlled accurately. On this basis, taking the formula feed for finishing pigs as research material, the pasting temperature, pasting time and feed moisture were selected as the influencing factors, and the degree of gelatinization was selected as evaluating indicators, thus the quadratic regression orthogonal rotatory combination experiments were carried out. As a consequence, the order of influence of each factor on feed gelatinization degree was feed moisture, pasting temperature and pasting time. A quadratic regression model (R2=0.9420) for feed gelatinization degree and three factors was established by regression analysis and response surface analysis with DesignExpert software, and the validity of the regression model was verified. In the analysis of chromatic aberration of feed samples after heat treatment, it was found that excessive heat treatment temperature would not increase the gelatinization degree of feed under certain conditions; on the contrary, it would intensify Maillard reaction leading to the deepening of feed color and affecting the appearance quality.

Abstract:The soy protein isolatephosphatidylcholine (SPI-PC) was used as a composite emulsifier to encapsulate benzylisothiocyanate (BITC). The nanoemulsion was prepared by a jet cavitation machine to improve its freezethaw stability. The effect of jet cavitation press and freezethaw cycle on the freezethaw stability of nanoemulsion was studied by using oil yield and stratification coefficient as stability index. The thermal characteristics of emulsion freezethaw process were used to compare different jetcavitation pressures. The thermal behavior of the modified soy protein isolatephospholipid was taken as an emulsifier emulsion during crystallization and melting of the emulsion during freezing and thawing. The results showed that when the jetcavitation pressure was 0.8MPa, the layering coefficient of BITC nanoemulsion was 51.39% lower than that of the untreated sample, and the oil yield was 83.64% lower than that of the untreated sample. The average particle size was (252±6.2)nm, the PDI was 0.114±0.034, and the zeta potential was (-27.2±0.6)mV. It was observed that BITC was embedded in the composite emulsifier and evenly distributed in the emulsion system, and it was in a relatively stable state. By comparing the difference in thermal characteristics of the sample, it was reflected that the jetcavitation modified proteinphospholipid could significantly increase the freezethaw stability of the emulsion. It provided a certain reference for improving the bioavailability of BITC in food and medicine.

Abstract:In order to study the relationship between water distribution change and water retention properties of yak meat during postmortem aging, explore the mechanism of water holding capacity (WHC) after slaughter, 10 male yak in Qinghai Province were slaughtered and aging within 4℃, then the pressing loss, drip loss, cooking loss and surface hydrophobicity index were determined during different aging times, and the water distribution was analyzed by lowfield nuclear magnetic resonance (LF-NMR) and nuclear magnetic resonance imaging (MRI), beef cattle were control group. The results showed that the pressing loss, drip loss, cooking loss and surface hydrophobicity index got the maximum value on the third day, which was significantly higher than other time points （p<0.05). It had the worst water holding capacity. Water distribution showed that at the early stage of postmortem aging, P22 was decreased and P23 was increased, at the later stage of postmortem aging, P22 was increased and P23 was decreased, in addition, P22 and P23 had a significant negative correlation （p<0.05), it indicated that the phase transitions existed between two kinds of moisture during postmortem aging. Nuclear magnetic resonance imaging reflected the spatial distribution of water, and the optimal maturity time was determined as 5 d, at this time, the image gray value was the highest and WHC was the best. Through comparative analysis, it was found that the WHC of the beef cattle was better than that of yak meat during the whole aging.

Abstract:Aiming to investigate the effects of tea polyphenols on the mitochondrial apoptosis cascade reaction mediated by mitochondrial oxidative stress and tenderness of yak meat during postmortem aging. The longissimus dorsi muscles injected with inhibitor tea polyphenol were taken as the experiment objects. The levels of mitochondrial oxidative stress, degree of mitochondrial oxidative damage, mitochondrial functional characteristics, process of mitochondrial apoptosis and change of meat tenderness in the control group and the treatment group were measured. The results showed that the level of mitochondrial ROS, MDA and carbonyl content in the treatment group was overall significantly or extremely significantly lower than that in the control group in the early of postmortem aging. At the middle and late of aging time, the SOD activity and the mitochondrial membrane fluidity was significantly or extremely significantly higher than that in the control group. After 24h, opening of the MPTP in the treatment group was significantly or extremely significantly lower than that in the control group. After 6~168h, the Cytc concentration of mitochondria in the treatment group was higher than that in the control group; during 72~168h, the Cytc concentration of cytoplasm in the treatment group was significantly or extremely significantly higher than that in the control group. Meanwhile, Caspase3 activity and MFI in the treatment group was significantly or very significantly lower than that in the control group at early aging time. The research demonstrated that tea polyphenols inhibited the role of the mitochondrial apoptosis cascade reaction on the meat tenderization by inhibiting ROS mediated oxidative stress damage of mitochondrial structure and function. These observations indicated that tea polyphenols acted as the antioxidants and antistaling agent in improving the quality of meat at the same time, may have adverse effects on meat tenderization from the angle of the mechanism of apoptosis tenderization and further confirmation was needed.

Abstract:During the progress of oil filling in the vehicle, the deviation between actual pressure and ideal pressure always affects the shift quality. For enhancing the shift quality, the model for simulation of the vehicle shift system was established, which included fuel supply unit, electromagnetic reversing valve, pressure regulating valve and clutch. The oil filling progress was simulated and analyzed in AMESim. Taking the oil filling pressure as optimization target, the optimized function was obtained on the basis of the error integral criterion. In pressure regulating valve, the key parameters affecting the oil filling pressure were obtained by the Pareto diagram as follows: the opening of the valve, the spring preloading force and the diameter of damping hole. Nonlinear programming by quadratic Lagrangian and genetic algorithms were respectively applied to optimize parameters above. According to the comparison between the optimized simulation oil filling curve and the ideal oil filling curve, the genetic algorithm was defined as the optimal algorithm, and the optimal structural parameters of the pressure regulating valve were determined. Based on the variable controlling approach, the experimental schemes were designed. The results of the experiments showed that the stability of the optimal shift system was improved to some extent, and the optimal oil filling process was more close to the ideal oil filling process, providing a reliable reference for improving the shift quality.

Abstract:A visual effervescent spray system and a gasliquid flow simulation model of atomizer interior and spray field were established to investigate spray characteristics of bubbly flow. The results showed that there was a gasphase expansion on spray surface, and the width of the gasphase expansion was increased with the increase of liquid mass flow rate and gasliquid mass ratio, distance between two expansions was decreased with the increase of gasliquid mass ratio. At the same gasliquid mass ratio, the spray cone angle was increased with the increase of liquid mass flow rate, and the influence of the liquid mass flow rate became weak at high liquid mass flow rate. The spray penetration distance was increased with the increase of liquid mass flow rate at low gasliquid mass ratio, while decreased at high gasliquid mass ratio. When the gasliquid mass ratio was low, the spray shape was apparently influenced by the gasliquid mass ratio, and the spray cone angle and penetration distance were increased with the increase of gasliquid mass ratio. As axial distance of the spray was increased, the droplet collision frequency was decreased and gradually became stable. The influence of gasliquid mass flow pulsation at atomizer outlet on the droplet axial velocity around the cross section of the atomizer outlet was limited to a very short distance. With the axial distance to the atomizer outlet increased, the distribution range of droplet size was widened, the number of peak droplets was decreased, and the peak size of droplet and droplet size distribution was moved to the direction of large size. With the increase of the axial distance to the atomizer outlet, droplet size in large scale droplet area was increased, the radial range of large scale droplet area was widened.

Abstract:There is a wide range of industrial applications for the 4DOF parallel mechanism which can achieve SCARA type output motion (three dimensional translation and one dimensional rotation). A novel fourdegreeoffreedom highspeed parallel robot mechanism for SCARA was proposed, which consisted of two RSS branches and two R(SRS)2R branches. Firstly, the topological structure characteristics such as the POC set of moving platform and mobility were first obtained based on the design theory of position and orientation characteristic （POC） set. Secondly, the virtual spring method was used to establish the stiffness model of the branch and the static of the branch was given. The differential mapping of the virtual joint deformation to the end deformation in the branch was obtained by the spin method and the Cartesian stiffness matrix at the end of the mechanism was obtained according to the static equation. By means of a nondimensionalization of the stiffness matrix, the 6×6 inhomogeneous stiffness matrix was decomposed into two homogeneous submatrices, of which two performance indices, corresponding to the translational and rotational stiffnesses, were defined to evaluate the stiffness behaviors of the manipulators. And the stiffness index analysis of the mechanism was carried out, and the stiffness characteristics of the mechanism in different working planes were analyzed. In addition, the dynamic analysis of the mechanism was performed to solve the velocity and acceleration of the active pair, the passive pair and the moving platform of the mechanism. The dynamic equation of the mechanism was established by using the virtual work principle. Finally, the simulation was compared with the ADAMS threedimensional model simulation to verify the dynamics. The correctness of the modeling laid the foundation for further research and practical application of the organization.

Abstract:The inverse robot kinematics problem has been extensively studied by many workers, but still some problems related to the complexity and strong nonlinear of the inverse kinematics process need suitable heuristic and adhoc techniques and simplifications. A novel method based on uniqueness domains notion was proposed. With using the boundary confirmed by robot’s Jacobian matrix determinant equal to zero, the joint space of the robot was divided into uniqueness domains with the same number of solutions as the inverse kinematics, and the boundary of each uniqueness domain was used as a constraint condition. Then the inverse kinematics solution in the uniqueness domain was transformed into the constrained optimization of the CMA-ES algorithm, the initial mean points of the CMA-ES algorithm in the uniqueness domain were optimized by using the characteristics of the uniform distribution of the good point set. The application of the presented method was described in detail by solving the inverse kinematics multiple solution of the 6R industrial robot, and comparing with the numerical method on Qianjiang No.1 industrial robot and the KUKA humanoid manipulator. The simulation results showed that under the precondition of accuracy requirement, the proposed method had a faster solution speed. For the industrial 6R robot, the average solution time of CMA-ES algorithm was about 5.1ms/time, and that of numerical method was about 7.5ms/time, and KUKA humanoid manipulator, the average solution time of inverse solutions was about 18.9ms/time, and the average solution time of numerical method was about 54.8ms/time. The presented CMA-ES algorithm stabilized the position tracking accuracy of both robots at 10-6mm level.

Abstract:A thermal error modeling method of NC machine tools based on deep learning method was proposed in order to improve the prediction ability of thermal error model. Fuzzy clustering method and grey relationship analysis method were used to select the sensitive points of temperature variables and the stacked automatic encoder (SAE) network was used to extract the features of the temperature variables from the selected input samples to construct the feature sets. Then, genetic optimization algorithm (GA) was used to optimize BP neural network parameters so as to propose a thermal error modeling method based on SAE-GA-BP neural network for NC machine tools. Taking a large gantry fivesided machining center as the experimental object, the spindle thermal error of the large gantry fivesided machining center was studied and selected as the main error source to achieve compensation in the machining process. The deep learning model of main shaft thermal error was compared with the multiple regression model. The experimental results showed that the proposed modeling method was better than the traditional multiple regression model in prediction accuracy of the thermal error of NC machine tools, which verified the feasibility and effectiveness of the proposed thermal error modeling method.

Abstract:Magnetorheological (MR) valves are widely used in hydraulic systems due to its fast response time and pressure drop regulation. A MR valve with mosquitoplate fluid flow channels was developed, and the fluid flow channels that was separated by mosquitoplate arc baffle between the damping disk and positioning plate mainly consisted of two Newtonian fluid circular pipe flow, one Newtonian fluid annular flow, two nonNewtonian fluid disk flow and two nonNewtonian fluid spiral flow. The working principle and structure of the developed MR valve was expounded, and the mathematical model of pressure drop was also derived. Finite element modeling of the MR valve was carried out by ANSYS/Emag software to simulate the electromagnetic field, including achieving the changes of the magnetic flux density along the fluid flow paths, and the variation of pressure drop and yield stress was also analyzed. The simulation results showed that the pressure drop can reach 5.58MPa at the applied current of 2.0A. The test rig of the MR valve performance was set up, and the pressure drop was tested under different applied currents and simulated load cases. The experimental results showed that the pressure drop can reach 5.1MPa when the applied current was 2.0A, which had better performance compared with that of conventional radial flow MR valve. At the same time, the experimental results showed that the designed MR valve had a faster response time at different flow rates, and the rising response time was shorter than that of falling response time. 

Abstract:As an engineering machine which loads and unloads gravel frequently, wheel loaders own large potential energy when the unloading process. In order to recover and utilize the potential energy, a closed pumpcontrolled threechamber hydraulic cylinder lifting device was proposed. The servo motor and accumulator supplied power for the device. A potential energy recovery chamber was added to the original boom hydraulic cylinder to form a threechamber hydraulic cylinder. The potential energy was recovered and utilized by an accumulator connected with the added chamber when the wheel loader dropped. The closed hydraulic system composed of the fixed displacement pump and the threechamber hydraulic cylinder was used to drive the lifting device, and the servo motor was used to drive the pump. In order to accurately control the extension and retraction of the hydraulic cylinder, the displacement feedback of the hydraulic cylinder was adopted to closedloop control of the motor speed. In the research, the mathematical model and the transfer function of closed pumpcontrolled threechamber hydraulic cylinder lifting device were established. Firstly, the static characteristics of the device were analyzed, and the corresponding control strategies were put forward. Then, according to the working principle and control strategies of the proposed device, a multidisciplinary electromechanicalhydraulic simulation model was constructed, and its feasibility, dynamic and energy consumption characteristics were analyzed. Finally, a test system of the proposed device was constructed to verify its dynamic and energy consumption characteristics. Based on the simulation and experimental results, the energy consumption of the proposed device was reduced by 21.2% in one working cycle under halfload condition comparing with the closed pumpcontrolled twochamber hydraulic cylinder lifting device. Compared with the original valvecontrolled hydraulic lifting device, the energy consumption of the proposed device under noload, halfload and fullload conditions were decreased by 22.7%, 20.9% and 21.5%, respectively.

Abstract:Doublestator multispeed hydraulic motor is a novel hydraulic component based on international patent technology. There are four motors in one shell for a doubleacting doublestator multimotor, each of these submotors can work alone or be combined depending on the actual requirement. The structure of socalled multimotor is different from the common ones, there is one rotor corresponding to two stators in a shell, which can achieve the constant displacement motor output with multi torques. It has the advantages of small size, light weight, simple structure, and high efficiency in specific power and can output several different flow rates. The doublestator hydraulic motor can work in differential connections, which expand the range of applications and improve the adaptability for the multimotors. As the distance between the inner and outer stator is equal, no returning springs or such mechanisms are required. In order to eliminate the adverse effects caused by the impact of flow distribution of doublestator vane motor, the valve structure of doublestator motor was improved, that was to open closed die compression angle and closed die expansion angle, which effectively achieved pre boost and pre pressure relief. The mathematical model of the closed dead angle of the doublestator motor was derived, and the characteristics of pressure change in the closed die cavity were analyzed. Based on dynamic mesh and its userdefined function (UDF) programming technology, the threedimensional numerical simulation of the twostator motor was performed. The results showed that compared with the existing doublestator motor, open closed angle can effectively reduce the phenomenon of high pressure backflow and abrupt pressure change, and made the change of oil pressure in transition zone tended to be more gentle, which laid the theoretical foundation for the reasonable design of doublestator components in the future.