Abstract:Due to the constraints of agricultural production conditions, such as regional differences, variety of crop types and planting patterns, agricultural machinery needs to meet the requirements of multi-functional, small batch, customization and diversification of customers’ needs. At present, all of Chinese agricultural machine enterprises generally focus on tracking and copying foreign agricultural machinery product, which lead to problems such as long development cycle, low efficiency of design knowledge reuse, and poor product reliability. The low competitiveness of products and lack of core independent technologies have bottlenecked the sustainable development of agricultural machine enterprises in China. To meet the diversified needs of users as the goal, intelligent design technology with knowledge based engineering (KBE), data management (DM), artificial intelligence (AI), virtual simulation technology and other modern information technology as means, the synergistic, automatic and intelligent design of agricultural machinery can be realized by integrating existing resources of related enterprises in the whole life cycle of agricultural machinery and product data management/product lifecycle management (PDM/PLM) collaborative design platform. It’s the key to improve the design level of agricultural machinery in China. Based on the characteristics of agricultural machinery, the definition, technical system, key technology and development status of intelligent design technology for agricultural machinery were introduced. The current situation and future development trends of the key technologies in intelligent design technology for agricultural machinery such as computer aided design (CAD), modular design, knowledge based engineering, virtual simulation, PDM/PLM collaborative design were deeply analyzed in recent years. And the reference suggestions for the research direction of agricultural machinery design were put forward.

Abstract:In order to improve the stability and robustness of agricultural machinery path tracking control under different speed conditions, a path tracking control method based on chain system model and small-scale stability analysis optimization was proposed. Firstly, the nonlinear kinematics model of agricultural machinery was established according to geometric constraints, and it was converted into linear chain system based on chain system model. The error items of the system were linearly combined to obtain the agricultural machine path tracking control method. Then, based on the stability analysis of the control method in the small range of the equilibrium position, the control method was optimized, and the stability of the agricultural machinery path tracking control in the small range of the equilibrium position was independent of the driving speed. The simulation verification control method can maintain stability at different speeds. Finally, the linear tracking contrast experiment and the agricultural machinery operation experiment were carried out with the rice transplanter as experimental platform. The results showed that compared with the PID control method, the proposed control method can maintain the stability of linear tracking control at three different speeds, and it had higher control precision. At the same time, the stability of the proposed path tracking control method was independent of the driving speed. When the driving speed of agricultural machinery was changed within the range of 0.4~2.0m/s, the proposed method can be kept stable, the average absolute error was 0.047m, and the maximum absolute error was 0.128m, which was suitable for complex agricultural machinery working environment.

Abstract:Aiming at the problem of injured seedlings caused by poor vision of drivers in the operation of plant protection machinery in high ground clearance, a method of assistant driving was proposed. A high-gap plant protection machine was taken as the research object, and a man-machine aided driving system was designed. Firstly, the hydraulic system design of the auxiliary driving system was elaborated in detail, on this basis, the structure of the steering system was improved. Secondly, based on preview algorithm and two-degree-of-freedom vehicle steering model, the front wheel angle control of steering system was studied. Finally, the control system software was created based on LabVIEW. The software control system included speed control system, navigation and positioning system and steering control system. Under the condition of 0.5m/s speed, the experiments were carried out on cement pavement and maize dryland respectively. The test results showed that the average linear path tracking error of auxiliary driving system was 5.2cm and the standard deviation was 3.4cm under cement pavement condition, and the average tracking error of auxiliary driving system was 6.8cm and the standard deviation was 4.8cm under the driving condition of corn crop between lines. Based on the above test data, it was concluded that the plant protection machinery auxiliary driving system met the field driving requirements. The auxiliary driving system designed had good practicability in wide-line crop cultivation.

Abstract:A linear trajectory tracking algorithm for tracking operation, could be used by the paddle boat for aquaculture. In order to cope with complex working environments, high-precision navigation must be adopted. The paddle boat could continue to be disturbed by wind and waves during the voyage. Interference could cause fluctuations in the track of the paddle boat. In order to realize high-precision navigation control of paddle boat and reduce influence of wind and wave interference, improve the stability of paddle boat process, save energy, reduce active frequency of the control system caused by the disturbance, and extend the duration of sailing and operation of paddle boat, a discrete sliding mode control method based on Kalman filter was proposed. Through the establishment of hydrodynamic model and yaw angle dynamic response model, the gain coefficient of discrete sliding mode control was designed and calculated. The negative feedback signal was denoised by two-dimensional Kalman filtering. After simulation verification and the actual boat was tested in the lake, and compared with the effect of PD control mode. As a result, the maximum overshoot was less than 25% of the PD control mode, the adjustment time was reduced by 50%, and the track deviation was less than 10cm. The discrete sliding mode control method based on Kalman filter achieved high-precision tracking of paddle boat, and the navigation process of paddle boat was more stable.

Abstract:A clamping maize precision seed metering device was designed based on the fitting of different structures of seed-clamping piece in each region and seed-pressing annulus to control the position and movement of seed to get a simple structure, improve the performance of maize seed metering device and meet the requirement of precision planting. The overall structure and working principle of the seed metering device were illustrated and analyzed by the size of maize seeds. The design of structural parameters of key components was conducted, such as seed-clamping piece and seed-pressing annulus. The rule of seed collection mechanics was got by analysis of seed collection process. In order to test the performance of clamping maize seed metering device, the experiment was employed through the method of single factor with Tiannongjiu (big size), Hongqi 688 (middle size) and Huangjinnuo (little size), three kinds of maize seeds. In test, working speed was taken as main influencing factor, the seed qualified index, and multiple index and missing index were taken as response index. The experiment indicated that the clamping maize precision seed metering device fit in the maize seed with big size better and the qualified index was 90.1%, the multiple index was 9.1% and the missing index was 0.8% with Tiannongjiu maize seed at working speed of 11km/h, which could meet the requirement of precision planting. The results can provide guidance and direction for the design and development of high-speed precision mechanical seed-metering device.

Abstract:In order to solve the problem of high multiple index of air-suction metering device and the difficulty in ensuring the rationality of design of clearing mechanism, the seed clearing mechanism of air-suction metering device was optimized. By defining the concept of the ratio of diameter of hole occupied by the seed when it was adsorbed, the mathematical model of the clearing process was established, the mechanism of the clearing process was analyzed, and the ratio of the minimum diameter of the hole occupied by the seed when it was adsorbed was obtained. The change of linear velocity of seed plate type hole was not obvious, but it was decreased obviously with the increase of type hole diameter. The installation position, chamfer of sawtooth edge and clearing curve of the clearing mechanism were analyzed and designed respectively. A parametric mathematical model for designing the clearing mechanism of air-suction metering device was established. The key factors affecting the shape of the clearing mechanism were seed size and radius of the type hole in the seed plate, while the linear velocity of the seed plate had little effect. In order to simulate and record the trajectory and parameters of any particle at any position and accurately simulate the working details of the seed cleaning process, the DEM-CFD coupling simulation method was used to simulate and analyze the seed cleaning process. By extracting the speed change index and observing the change of seed speed, the impact of seed cleaning mechanism on seeds was obtained. It was verified that the designed clearing curve can play a good role in clearing seeds step by step. The order of impact force of seed cleaning from large to small was large flat, small flat and round shape. Choosing Zhengdan 958 non-graded seeds and the optimized clearing mechanism was compared with the previous metering device. In order to ensure the same working conditions, the same air pressure of -3kPa was used to carry out the experiment. Three times of test data were selected to take the average results. The result showed that the qualified index after optimization had a certain degree of improvement compared with that before optimization, and with the increase of operation speed, the rising extent of qualified index was increased, and the optimized multiple index was decreased significantly. This trend was increased with the increase of speed, and the missing index did not increase with the decrease of multiple index, but it was decreased slightly while maintaining the original level of missing index. The optimized metering device was operated at speed of 8~14km/h, the qualified index of the optimized metering device was not less than 92.0%, the multiple index was not more than 1.6%, and the missing index was not more than 6.3%. The optimized clearing mechanism can reduce the seed missing while reducing the multiple index, effectively improve the qualified index, and verify the rationality of the mathematical model design of clearing mechanism parameters. The maize seeds of Zhongke 11, Zhengdan 958 and Zhongyuandan 32 were selected for the comparative experiment at the speed of 14km/h. The results showed that they had good adaptability to different varieties of seeds. This model can design clearing mechanism according to different seeds and metering device sizes, which provided a basis for the design of air-suction metering device clearing mechanism.

Abstract:There will be some problems when subsoiling, such as the large residual of clods and heavy load of the device. The interactional subsoiller-stubble was designed for solving these problems. According to the kinematics analysis and field test, the excursion of the included angle between the blade curve and the ground was sure to be 10°~70°, the minimum radius of the stubble chopper was 180mm, the middle radius was 215mm, the maximum radius was 235mm, and the minimum distance between subsoiler and stubble chopper was 20mm. The design was verified to be reasonable by discrete element simulation experiment. The field test indicated that to compare the interactional device with reference indicator, the stubble ratio was increased by 10.92%, the rate of crushing soil was increased by 6.04% and the oil consumption was decreased by 31.39%. Contrast test showed that under the same operating mode, to compare interactional subsoiler-stubble chopper with subsoiler-stubble chopper, cutting disc and the stubble chopper with breach, the average stubble ratio was increased respectively by 3.53%, 19.38% and 8.86%;under different operating modes, compared with subsoiler-cutting disc, when the average load was decreased by 20kg, the stubble ratio was increased by 13.8%, when the average load was decreased by 40kg, the stubble ratio was increased by 5.82%;compared with the stubble chopper with breach, when the average load was decreased by 20kg, the stubble ratio was increased by 4.5%, and the oil consumption was decreased by 12.79%. The interactional device had a better performance when the load was reduced.

Abstract:Traditional rotary tiller (TR), straw rotary burying and returning machine (SR) and subsoiling combine straw rotary burying and returning machine (SSR) were simulated by discrete element method and compared with field experiments. The spatial coordinate of straw in soil was measured by the developed measuring device of straw three-dimensional coordinate, and the spatial state of straw in soil was restored in the three-dimensional drawing software. The straw was quantified and visualized in the three-dimensional drawing. The uniformity of vertical and horizontal distribution of straw in soil were studied by layer, horizontal and vertical division of sampling cubes. The corresponding simulation models were established in the discrete element software, and the same operation parameters were set up with the field experiment. After the simulation work was completed, the amount of straw in the area were calculated by setting different Geometry Bins. They corresponded to the actual field operation of the layer, horizontal and vertical division. The results showed that in the layer process, both the simulated and measured values, the amount of straw buried in the soil by SR and SSR was significantly larger than those of TR, especially in the lower layer of soil, which was several times as much as that of TR. In the layer treatment, the variation coefficients of the simulation and measurement of straw proportion in different layers after TR, SR and SSR operations showed a decreasing trend, and the variation coefficients of SSR were the smallest, which were 28.8% and 28.7%, respectively. The variation coefficients between simulated values and measured values under three kinds of tillage equipment were not very different, with an average error of 9.6%. There was no absolute regular of variation coefficients between simulated and measured values of straw proportion of TR, SR and SSR in the landscape orientation and portrait division, but the variation coefficients of SSR were the smallest in the whole, which showed that the uniformity of vertical and horizontal distribution of straw in soil was the best after SSR straw incorporation, whether in discrete element simulation or field experiment. On the whole, the discrete element simulation fitted the spatial distribution of straw well after field operation, and the relative error was within acceptable range.

Abstract:Due to the phenomenon of transplanting arm mud-dumping in the process of transplanting in the existing Bezier gear planetary gear system rice seedling transplanting mechanism, the causes of the problems caused by the operation trajectory were analyzed, and the transplanting trajectory improvement and solution of mechanism parameters were carried out based on the analytical theory of precise multi-position motion. According to the position and attitude requirements of the three actions of the beginning, the end and the pushing of seedlings during transplanting process, the three precise pose points of the constrained transplanting trajectory were determined. The design process of the gear-train transplanting mechanism was divided into two stages: the motion synthesis of the open-chain 2R mechanism (obtained by removing all gears except the output gear) and the design of the unequal speed transmission ratio. Based on the synthesis method of three-position motion generation mechanism with given link length, the curve equations of the center point (the input point of gear train mechanism) and the circle point (the output point of gear train mechanism) of the open chain 2R mechanism were established and the position curves corresponding to the circle point and the center point were obtained when the length of the rod was different. The desired trajectory with key point position information was fitted. The angular displacement of the open-chain 2R mechanism based on the trajectory was solved and its monotonicity was analyzed, solution and distribution of the total transmission ratio of the mechanism were realized. Transplanting mechanism of rice seedling with seven-gear planetary wheel was designed, and the simulation and bench test were carried out. Through the comparison with the theoretical and experimental results of the original mechanism, it was found that the angle between the backhaul section of the transplanting path of the new mechanism and the ground was increased to 90°, the height of the buckle was increased to 68mm, and the distance between the seedling point and the lowest point of the rotation center of the box was increased to 21mm. The transplanting quality of rice seedling was improved.

Abstract:The transplanting synchronous puncher with preventing clogging developed by Northeast Agricultural University was used mainly in rice transplanting on the mulch by utilizing physical punching method, which can realize efficient of transplanting. In order to achieve that the transplanting machine completed job mode of laying of fibrous mulch film, opening, and transplanting in a process and solve the problems of root injury and stoppage of device when transplanting on the mulch, the development of a transplanting synchronous puncher with preventing clogging was absolutely necessary. On the basis of the arm-distributing mechanism of the gear rotating box, a single-arm opening device with a “+” shape point was added. Based on analysis of the cooperating relationship among three systems (gear transmissions, planting arm and synchronous puncher), planting arm was selected as research object to establish a mathematical model of synchronous puncher by analyzing the kinematic process between claw and mulch. Using the established model for simulation, the main factors affecting the quality of the opening were determined, and the feasible range of the difference between the phase angle of the opening and the insertion was verified. Using the quadratic orthogonal rotation center combination test method, the difference between phase angle of opening and insertion, the inclination angle of opening and rotation speed of rotating box were taken as the test factors, and the length of the film hole, length of opening before insertion, and pass rate of opening were evaluated. The results showed that when the difference of the phase angle between the opening and transplanting was 8.0°, the inclination angle of the opening was 7.0°, and the rotation speed was 246.4~250.1r/min, there was no blockage in the opening device. The average length of membrane hole, the average width of membrane hole, the average length of opening before transplanting were 47.3mm, 16.6mm and 18.0mm and the average qualified rate of membrane hole was more than 94%. Based on the results of parameter optimization test, the anti-blocking performance and perforation performance of the anti-blocking film-covered synchronous opening transplanting device and the “H” synchronous opening transplanting device were compared. The perforation device designed was superior to the “H” type perforation device before improvement, and it met the agronomic requirements.

Abstract:Aiming at the unclear relationship between spray parameters of nozzle and atomization parameters in the aviation spray mode, and considering the urgent need of precision aerosol spray, spray performance test and agent mathematical model modeling method were combined to discuss the influence of main working parameters on atomized particle size and spray width for the CN1215 special aviation centrifugal nozzle. The operating parameters of the liquid supply system corresponding to the spray parameters of the centrifugal nozzle were calibrated, and then the variation laws of droplet size and spray width under the influence of the working parameters (flow rate range was 100~350mL/min, nozzle rotating speed was 8000~10000r/min) were also analyzed in an indoor windless environment. Secondly, taking the spray parameters of the nozzle (nozzle flow, nozzle speed) as the test factor, and taking the droplet diameter (Dv50) and the spray width corresponding to droplet diameter (Dv50) as response factor, three kinds of mathematical methods, including fourthorder response surface method (RSM), Kriging method and ellipsoidal basis function neural network (EBFNN), were used to approximate the relationship between experimental factors and response factors respectively. The agent mathematical models between the nozzle atomization parameters (Dv50, and corresponding spray width) and nozzle operating parameters (nozzle flow, nozzle speed) were established. The decisive coefficients R2 of the three agent models for the particle size Dv50 were 0.705, 0.718 and 0.925, and the decisive coefficients R2 of the three agent models for the Dv50 corresponding spray width were 0.819, 0.890 and 0.930, respectively. Based on the EBFNN implicit proxy mathematical model, the response surface of two atomization parameters was established, the rapid prediction of droplet Dv50 and spray width under the influence of working parameters was achieved. Based on the EBFNN implicit proxy mathematical model, the response surfaces of two atomization parameters were established, which realized the rapid prediction of droplet Dv50 and spray amplitude under the influence of spray parameters. It was of great significance for accelerating the development of aviation precision pesticide application.

Abstract:The research on material air separation mechanism and the obtained relevant parameters is important basis for the design of air separation machine. The “dry shell and wet kernel” material of hickory after breaking was taken as the research object. Through mechanical analysis and coupling simulation of material, the parameters of material recovery coefficient, static friction coefficient, rolling friction system, particle free suspension velocity and instantaneous acceleration during collision were clarified. On this basis, an air separation test platform was designed for the aerodynamic characteristics of hickory for experimental research. According to EDEM and FLUENT coupling simulation, high-speed camera and professional measuring instruments, the required wind speed range, design parameters, motion trajectory and mechanical parameters were determined. The simulation model was verified to be applicable to the design and simulation test of virtual prototype by comparing simulation and test-bed test results. The suspension velocity range of each material of Carya cathayensis obtained by the experimental typhoon selection test was as follows: one dew kernel was 6.8~10.3m/s, two dew kernels was 7.5~10.1m/s, broken kernels was 6.9~9.8m/s, two dew shells was 5.3~7.9m/s, broken shells was 4.8~7.6m/s, and shell-kernel chimes was 5.9~9.4m/s, respectively. The mixed material test confirmed that the overall cleaning rate was 99.2% and the false selection rate was 0.8% when the wind speed was 8.2m/s, the water content of kernel was 23.6%, the water content of shell was 5% and the windward face ratio was about 50%. The maximum impact force of the remaining materials was 0.0031N when the water content was 23.6%, the wind speed was 11.7m/s, and the cleaning rate was 100%, the false selection rate was 2.3%, and the water content was 23.6%. The research provided reference for the research and development of pecan air separation technology and equipment.

Abstract:In order to improve the completely mechanical production level of hydroponic lettuce, an automatic packaging machine was designed and manufactured. It mainly contained guiding device, film cutting and covering device. The packaging machine could implement putting lettuce into packaging box lengthways and covering film automatically. The lettuce was put into the box by cylinders, and a guiding annulus was utilized to decrease lettuce excursion and reversal. The flexible brush combed the selfadhesive film on the box. The size of the packaging box, the parameters of guiding device, and the parameters of film cutting and covering device were confirmed by lettuce extrusion test, mechanical analysis and theoretical calculation, respectively. The influence of guiding annulus on lettuce position and posture characters, for instance the horizontal excursion and attitude angle, was analyzed by highspeed photograph. The packaging test results showed that the average value of horizontal excursion with guiding annulus was 5.8mm when lettuce entering the box, which was reduced by 75.0% than that without guiding annulus. The average value of attitude angle with guiding annulus was 17.9°, which was reduced by 74.2% than that without guiding annulus. The guiding annulus could ensure the success rate of putting lettuce into the packaging box. The optimized combination of film cutting parameters was obtained by orthogonal tests, and the angle between longitudinal cutter and film, film stretching velocity, and film transverse cutting velocity were 30°, 300mm/s and 500mm/s, respectively. The verification test results showed that the success rate of packaging was 96%, and the single packaging operation time of prototype was 10.5s, and it was reduced by 58% than that of manual operation.

Abstract:Precessing vortex rope (PVR) in Francis turbine draft tube is an unsteady swirling flow under a given partial load operating conditions and characterized by high-amplitude pressure fluctuation, and the pressure fluctuation excited by PVR can cause several directed and adverse effects on the operating stability or even fatigue damage. Numerical solution with SST k-ω turbulent model and experimental test were respectively carried out to investigate the internal flowing of draft tube towards a model Francis turbine operating at 42.35% of rated power. An excellent agreement between numerical and experimental results of pressure fluctuation amplitude and frequency was obtained with corresponding errors of 2.70% and 2.62%，respectively. The monitored pressure pulsates periodically at low frequency of 0.25 time of the runner revolution frequency, the monitoring positions travelled over by the PVR structure captured a minimum pressure value, and higher pressure amplitude compared with the rest regions due to the movement of vortex structure. In order to further clarify the complex flow features and dynamic characteristics towards the PVR, the pressure signals measured was decomposed into the synchronous and asynchronous components. Relative to the synchronous component, the decomposed asynchronous component remained the same frequency as the frequency of vortex rope evolution and obtained an absolute dominance of pressure fluctuation amplitude. On the contrary, the dominant frequency of synchronous component was changed with lower pressure amplitude. The analysis indicated that the contribution of the nonsynchronous component to the formation of the vortex rope was greater than that of the synchronous component. At different elevations of draft tube cone, the quantitative analysis to the amplitudes showed that the asynchronous component held leading status, the amplitude of asynchronous component was increased initially and then decreased along the flow direction, while the synchronous component amplitude kept increased.

Abstract:In order to improve the uniformity of the pneumatic fish pond feeder and the feed utilization rate, the performance analysis and numerical simulation of the throwing process by EDEM-Fluent coupling method were carried out. The main reasons for the uneven distribution of throwing were studied, and the structure of feeder was optimized. The simulation analysis showed that the structure of feed chamber and guide plate were the key factors affecting the throwing performance. On the basis of optimization of parabolic structure, the threedimensional two regression orthogonal rotation test was designed by Design-Expert software. The effects of the factors such as the radius (Ro) of the external cavity, the height (ho) and the angle (α) on the uniformity of the parabolic were studied. Then, the multivariate regression model between the variation coefficient of circumferential distribution (Cv) and the factors of Ro, ho and α was established. And then, the optimal design parameters were determined and the site verification test was carried out in Agricultural Machinery Test Site of Nanjing Agricultural University. The results showed that the influence of each factor on the circumferential variation coefficient in primary and secondary order was as follows: α, Ro, and ho. The circumferential uniformity coefficient of variation was the smallest (14.13%) when Ro was 77.00mm, ho was 85.40mm, and α was 93.20°. Meanwhile, the test result was 15.08%, which was consistent with the theoretical value of the model, and it was decreased by 50.50 percentage points compared with the prior optimization. Therefore, it was feasible to optimize the performance parameters of the pneumatic feeder based on the EDEM-Fluent coupling method, and get better parabolic uniformity. The research result provided a reference for the design of a good feeding equipment and similar parabolic performance analysis.

Abstract:To reduce the losses of bruising and damage, an appropriate available potato-soil separation technology is essential during the potato harvesting process. Combined with the agronomic techniques of potato cultivation in the north of China, a potato harvester with double cushions at low position laying stage was designed, which was developed with the potato-soil-impurity separation technology of vibration separation, double cushions, and low position laying. The harvester was mainly composed of excavating device, soil loosening and depth limiting device, low position laying and separation device, 2-level vibration device, soil cutting and seedlings cutting device, double cushions, soil compacting and flatting device and other parts. The kinetic models were established at the low position laying stage, and structural parameters of primary components were determined. The potato-soil separation device was divided into vibration separation stages and low position laying separation stage with double cushions, to improve the harvesting efficiency and reduce the harvesting losses. The loosening and depth limiting device was improved to reduce the bruising and damage. Simultaneously, the soil compacting device could effectively prevent potatoes from being buried by soil again after being excavated and separated, which was conducive to picking up and improving the average exposing rate. By impact recording technology, the impact characteristics of potatoes were analyzed at low position laying segment. It was shown that by the test results, the productivity was 0.41hm2/h and 0.54hm2/h, the damage rate was 1.03% and 0.84%, and the bruising rate was 1.52% and 0.95% at harvesting speed of 0.88m/s and 1.16\m/s, respectively. It was noteworthy that the performance indexes met the relevant standards. The research result provided a reference for further study on reducing the potato-soil separation losses to minimum and the optimization and the improvement of separation technology.

Abstract:Based on time series Landsat8 images of atmospheric collected in 2015，the change rules of normalized vegetation index (NDVI) and enhanced vegetation index (EVI) with the increase of vegetation coverage were studied. Their monitoring vegetation cover differences were analyzed quantitatively. The differences of NDVI and EVI distribution frequency curves and the differences of NDVI and EVI time series curves were analyzed. The results showed that NDVI and EVI were increased most rapidly when vegetation appeared on the surface, and with the increase of surface vegetation coverage, the increase rate of NDVI and EVI slowed a descending trend. NDVI with low vegetation coverage was increased faster than EVI, NDVI with medium vegetation coverage was close to EVI, and NDVI with high vegetation coverage was increased lower than EVI. Under different vegetation coverages, NDVI value was always greater than EVI value. NDVI and EVI distribution frequency curves can describe the number of pixels of different vegetation coverage and the change with time. NDVI and EVI time series curves can clearly reflect the growth change rule of a crop and the growth difference of different crops in the same period. The following conclusions were drawn: in the early stage of crops growth or under low vegetation coverage, NDVI and EVI overestimated vegetation coverage, and estimated value of NDVI was slightly higher than that of EVI’s. Their ability to describe vegetation was similar in the middle growth stage or in the middle vegetation coverage. EVI was more sensitive than NDVI to monitor crops growth during crops growth peak or under high vegetation coverage. To sum up, NDVI and EVI may be reasonably selected according to the change characteristics of vegetation coverage during crops growth period, and NDVI and EVI may also be used to supplement each other.

Abstract:Winter wheat take-all is a quarantine disease that causes wheat to be significantly reduced or even rejected. Rapid and non-destructive monitoring of the spatial distribution of winter wheat take-all is of great significance for its prevention and control. The UAV-equipped imaging hyperspectral sensor was used as the remote sensing platform. The imaging hyperspectral image combined with the ground disease survey data was used to try to map the distribution of wheat take-all in the field scale. The quality of UHD185 spectral data was evaluated by synchronously acquired terrestrial ASD hyperspectral data. The statistical analysis and remote sensing inversion mapping techniques were used to calculate the differential spectral index (DSI) and ratio spectral index (RSI). Normalized difference spectral index (NDSI) and disease index (DI) were constructed to determine the coefficient equipotential map, and the optimal spectral index and DI were constructed to construct a linear regression model, and the partial least squares constructed with three indices were constructed. The accuracy and robustness of the prediction model constructed by regression method were compared. Finally, the model was tested with independent data. The results showed that the ASD spectral data of winter wheat canopy was significantly correlated with UHD185 spectral data, R2 was above 0.97, and the three spectral indices were compared with DI to construct a partial least squares regression model and the model verification results were obtained (R2=0.6292, RMSE is 10.2%, MAE is 16.6%). The results showed that DSI(R818,R534) had the highest contribution to the model with the formula for linear regression model of DSI (R818,R534) and DI as y=-6.4901x+1.4613 (R2=0.8605, RMSE is 7.3%, MAE is 19.1%), which was verified by independent samples for model accuracy (R2=0.76, RMSE is 14.9%, MAE is 11.7%, n=20). Finally, the model was used to invert the DI of the plot, and the spatial distribution map of winter wheat take-all was made. The research provided a technical basis for UAV hyperspectral remote sensing in the accurate monitoring and application of winter wheat take-all. It provided a theoretical basis for the future satellite remote sensing to explore large-scale monitoring of winter wheat take-all.

Abstract:Drought is one of the most serious natural disasters and a threat of food security. It is extremely important to have accurate and timely early warning of drought for prevention and reduction of agricultural disasters. Current method of drought early warning was characterized by weak mechanism, low spatial resolution and lack of crop growth information. A daily crop growth and soil moisture dynamics simulation system using a soil water dynamic model in northern winter wheat zone was constructed. Based on this soil moisture simulation system, a drought early warning system for winter wheat was constructed. Daily drought early warning products from April to May in 2018 were generated by using this warning system. The results showed that forecast accuracy of soil relative moisture in next 10 days was high since its coefficient of determination was 0.63~0.91 and its root mean squared error was 5.6%~18.2%. The closer soil moisture forecast was in time, the more accurate was. Forecast accuracy of drought grades for severe and extreme drought was higher than those of mild and moderate grade. This drought warning system satisfied the needs of drought early warning in national agro-meteorological service department in China. The research result would provide scientific basis for prevention and reduction of agricultural disasters and national drought early warning services.

Abstract:Vegetation index temperature mixed pixels affects the remote sensing monitoring of drought conditions, Water deficit index (WDI) was compared with surface minus air temperature (Ts-Ta) as a water stress indicator which can overcome the difficulty. The experimental field was located in Dalat Banner, Inner Mongolia, and the experimental object was silage summer maize. Normalized difference vegetation index (NDVI) and land surface mixing temperature (Ts) were extracted from UAV-acquired images (multispectral, thermal infrared). Maize physiological parameters and meteorological data were collected to establish WDI model, under three irrigation regimes. WDI model and remote sensing data (NDVI, Ts) were used to generate vegetation indextemperature trapezoidal space, WDI map, and Ts-Ta map. WDI and Ts-Ta were extracted in the sample area. WDI and Ts-Ta were extracted in sample areas. The relationships between WDI or Ts-Ta and soil water content/stomata conductance were analyzed. Results demonstrated that vegetation indextemperature trapezoidal space, WDI and Ts-Ta map were sensitive to shortterm drought response. WDI and Ts-Ta showed similarity, both showed strong correlation with soil water content and stomata conductance (R2=0.4～0.85). At scale of ten days, the correlation between WDI and soil water content/stomata conductance (R2>0.68) was significantly higher than the correlation between Ts-Ta and soil moisture content/stomata conductance (R2<0.6). At the scale of ten days, the effects of different water stress gradients on drought monitoring were analyzed. It was found that under sufficient irrigation, there was no significant correlation between WDI or Ts-Ta and soil water content/stomata conductance (R2<0.12). Under different deficit irrigation, the correlation between WDI and stomata conductance/soil water content was significant (R2=0.7283~0.82), the correlation between Ts-Ta and stomata conductance/soil water content showed large fluctuations (R2=0.3566~0.8074). WDI had greater practicability and stability when monitoring the continuous change of drought compared with the difference in land temperature, at the scale of ten days.

Abstract:Crop harvest time has an important impact on crop yield and quality. The development and wide application of remote sensing technology provides an effective method for large-area and real-time monitoring of crop growth. However, remote sensing cannot capture changes in its intrinsic mechanism characteristics. Therefore, a framework that assimilated leaf area index (LAI) derived from remote sensing data into crop growth mode was presented to predict the maturity of crops. LAI was used as the coupling variable, moderate resolution imaging spectroradiometer (MODIS) LAI was used as the remote sensing data source, meteorological data and meteorological forecast data of 2017—2018 were used as weather input of world food studies (WOFOST) crop growth model, May 1st as the predicting date. By means of shuffled complex evolution method developed by the University of Arizona (SCE-UA) algorithm, it was simulated in each pixel in the study area and retrieved the optimal parameters set of this pixel. Then the WOFOST was run by the optimal parameter set to simulate the growth and development of winter wheat and retrieve the maturity-prediction. Verified by the observation data of the agrometeorological sites in the study area, it was demonstrated that the method had substantial accuracy in predicting regional anthesis and maturity date with the root mean square error (RMSE) as 2.10d and 2.48d. The method provided a reference for the maturity prediction of other crops at a regional scale.

Abstract:It is a challenge to acquire accurately regional crop structure information by using remote sensing technology at county scale for the possible reasons of cultivated land fragmentation, scattered distribution and complex planting structure. Jingtai County was taken as the research area, and multitemporal Sentinel-2A remote sensing image was used as the data source to construct the time sequences of five kinds of feature parameters, which were normalized difference vegetation index (NDVI), red edge normalized vegetation index (RENDVI), and their combinations (NDVI+RENDVI, NDVI-RENDVI as well as NDVI&RENDVI). The random forest method was used to classify the crops based on five kinds of feature parameters. The results were as follows: according to the shape, the multitemporal VI (vegetation index) feature curve of crops was divided into three types, which were called highlevel, including corn, rice, flax and potato, lowlevel, including onion, greenhouse crops and sandyfield crops, and openend type, including spring wheat and spring wheatautumn oil sunflowers, respectively. Openend type could be identified by images of May or September, meanwhile, highlevel type and lowlevel type could be distinguished by images of July or August. Among each type, crops could be identified by using images of different times. For highlevel type, four crops showed significant differences in the images of mature period, for lowlevel type, images in September could supply much information to distinguish two crops, and as for as openend type, there were significant differences for three crops all through four growing stages. The sequence of overall accuracy of classification results by five kinds of feature parameters from large to small was NDVI&RENDVI, NDVI, NDVI+RENDVI, RENDVI and NDVI-RENDVI. 

Abstract:The accumulation volume is an important indicator for evaluating the quantity and quality of forests. In order to analyze the impact of open pit mining and land reclamation on stand growth, it is necessary to quickly and accurately determine the stand volume of unaffected areas, damaged areas and treated areas. Due to the complex and varied environment of the mining area, in order to avoid danger, it was proposed to use the ground photogrammetry method to collect field data, and then use the fivetree method as the principle, and combine the derivation shape method to quickly calculate the volume of mixed forests. Comparing the DBH of the 25 trees measured by the ground photogrammetry with the DBH measured by the wooden ruler method, the absolute error of the average DBH was 0.23cm, and the relative error was 1.35%. It was indicated that the noncontact ground photogrammetry method can replace the method of measuring the diameter of breast with each wood ruler. The ground photography and the fivetree method were used to conduct tree surveys on the unaffected areas, damaged areas and treatment areas of Pingshuo mining area. The results showed that compared with the unaffected area, the average breast diameter of the damaged area was decreased by 21.26%, and the accumulated amount was decreased by 41.14%. Compared with the damaged area, the average breast diameter of the treated area was increased by 1.46%, and the accumulated amount was increased by 17.80%. It was showed that openpit mining affected the average DBH and accumulation of forest stands in Pingshuo mining area, especially the impact on the accumulation volume. Land reclamation improved the growth of trees to some extent.

Abstract:Digital elevation model (DEM) is a basic surface information product for constructing hydrological models, drawing slope maps, and extracting topographic features and so on. Because unmanned aerial vehicle (UAV) light detection and ranging (LiDAR) point cloud data has discrete characteristics, a reasonable interpolation method needs to be selected when generating DEM based on point clouds. The desert vegetation area in Xinjiang was taken as the research background, the zero-mean normalization method was used to normalize the point clouds’ echo intensity, the elbow method was used to determine the optimal number of clustering by K-means approach, and the K-means clustering method was used to cluster the point clouds’ intensity values to obtain the test area’s ground point clouds. After that, the Kriging interpolation method was used to interpolate the ground point clouds with the thinning rate of 20% and 80%, respectively. Furthermore, the point clouds’ elevation value was used as a variable to establish the radical basis function neural network (RBFNN) prediction model, the accuracy of RBFNN prediction model was analyzed by linear regression method, and then the highprecision DEM was generated by Delaunay triangulation interpolation. The results showed that Kmeans clustering method was adopted to realize the clustering with the optimal number of clustering as 4, and 48722 ground point clouds were obtained. The root mean squared error (RMSE) corresponding to the point cloud thinning rate of 20% was smaller, and RBFNN training time was 56s when the point cloud thinning rate was 20%. The determination coefficient R2 of fit for predicting the point clouds’ elevation value was 0.887, and RMSE was 0.168m when elevations of ground point clouds was predicted based on RBFNN. This method not only showed that the point cloud filtering can be realized by K-means clustering filtering, but also showed that the RBF neural network was a better way for predicting point cloud elevation. This can provide reference for constructing high-precision DEM based on point cloud.

Abstract:Sound technology is an effective method to monitor animal behavior. Animal vocalization can reflect their individual health status and individual needs, and can be used as an assisted indicator for evaluating animal welfare and animal comfort level. In the process of laying hens’ breeding, it is helpful for farmers to understand their animals by effectively identifying different types of laying hens’ vocalization, so as to improve the production efficiency as well as animal welfare. A method of classification and recognition of Hy-Line Brown laying hens’ vocalization was introduced based on texture features of spectrogram. The method combined image processing with sound processing technology to analyze voiceprint information hiding in the two-dimensional spectrum of spectrograms from laying hens’ vocalization, and then the texture features were extracted from spectrogram by using 2D-Gabor filter. Subsequently, machine learning algorithm like backpropagation neural network was used for sound classification and recognition. Kinect for Windows V1 was selected as sound input device, and LabVIEW and Matlab software were used for developing the algorithm of sound data acquisition and sound analysis, respectively. The experimental results showed that the average precision rate and sensitivity rate were no less than 92.0%, and the sensitivity rate of fan noise was the highest one, which was 99.3%, and the sensitivity rate of normal calls was the lowest one, which was 76.0%. The research result can provide a visual and noninvasive method for farmers to identify the specific vocal behavior of laying hens, and also provide a feasible reference means for indepth study of animal behavior and welfare.

Abstract:The surface defect plaque of spherical fruit is an important criterion for grading and sorting. Given the problem of the shape and size distortion of the plaques in the image by machine vision online sorting, according to the principle of projective geometry and general imaging configuration, the general imaging equation and the universal imaging area algorithm for plaque were established, and the area distortion law of plaque image was analyzed. Based on these above, the relationship between the effective image region and the parameters of the imaging system was calculated by Matlab to meet the requirements of the specific sorting accuracy, and a simple method for defining the effective image region was proposed. Using hemispheric blocks and Egyptian sweet oranges as the test subjects, the area distortion of the defective plaques located in the demarcated area captured by industrial cameras were verified with NI Vision Assistant. Assuming the distortion threshold (A) was 20%, the minimum spherical center angle (λ0min) could be calculated and the result was 7932°, and then the effective image area was designated. The experiment showed that the distortion degree of the defect plaques in the delineated area on the five hemisphere blocks were all less than the setting threshold under the specific image conditions. Similarly, for the five Egyptian sweet orange samples, the proportion of defective plaques that satisfied the distortion requirement were orderly 97.38%, 97.33%, 94.22%, 96.44% and 97.78%. Thus it’s available that the predicted results based on the general equation of spherical fruit surface plaque imaging can be used for the effective region segmentation to realize the effective control of sorting accuracy. The sorting threshold judgment by determining the area of defective plaques in the effective image region was conducive to simplify image processing, which can provide theoretical guidance for the imaging parameter configuration of the spherical fruit imaging system.

Abstract:The visualization of the spatial distribution and topological structure of soil pores plays an important role in understanding soil ecological processes. Thus the research on the soil pore skeleton extraction algorithm was carried out. Based on the custom rule structure and the soil pore structure, the performance of the thinning method and distance transformation method to construct the pore skeleton model were evaluated. The experimental results showed that the skeletal model construction effects of the two algorithms were not affected by the model type. Among them, the skeleton model constructed by the distance transformation method missed voxel points and some voxel points tended to be off the center. While the pore skeleton model extracted by the thinning method had perfect centrality, connectivity and topological invariance, whose average skeleton offset distance (0.10mm) was 50% lower than that of the distance transform method (0.15mm). Through the comprehensive analysis of three indicators of refinement, connectivity and centrality, the thinning method had superior ability to describe the shape and topological characteristics of soil pores. The research laid a technical foundation for the study of soil physical structure and hydrological characteristics, and a theoretical foundation for understanding soil function from pore scale.

Abstract:Ecological land patches with greater ecological service value are an important guarantee for maintaining regional ecological security in the semiarid areas of Northwest China. Eco-service plaques with small ecological service values rely on large plaques. In the natural state, plaques of different sizes have a distinct hierarchical nature. A hierarchical network extraction model framework was constructed with Baotou City as the research area, combining with the hierarchical nature of different ecological value habitat patches. The hierarchical ecological network was evaluated by selecting appropriate graph theory network measurement indicators. The results showed that the hierarchical ecological network was constructed based on the hierarchical network extraction model, so the number of the first, second and third layers of ecological sources was 8, 31 and 123, and the number of potential corridors on the first, second and third floors was 8, 35 and 151, and the corresponding number of the first, second, and third layers of ecological nodes was 7, 28 and 47;the α, β, γ indexes were calculated to evaluate the hierarchical network structure, with the increase of the low-level source and the number of corridors, the more loops available for material flow in a low-level network was, the lowerlevel ecological networks were better than the higher-level average connectivity. The hierarchical ecological network constructed for semi-arid areas can provide theoretical guidance for the ecological construction of Baotou City and had important reference value for semiarid urban ecological planning.

Abstract:The rapid expansion of the desert poses a huge threat to the socioeconomic and environmental conditions of ecologically fragile areas. Dengkou County of Bayannaoer City, Inner Mongolia, which located in the desert oasis area, was selected as the study area. Remote sensing image data and digital elevation model (DEM) data were used as research materials, and 11 simulation scenarios of development strategies were set up for this region. A multiple scenario simulation model of the ecological network (the FG eco-network multi-scenario simulation model) was constructed, and the gravity model and the minimum cumulative resistance (MCR) model were used to extract the forest-grass ecological network (FG eco-network) in the study area. The complex network theory was used to analyze the topology and statistical characteristics of the FG econetwork in 11 development scenarios. The results showed that the ecological network connecting ecological patches in the study area was gradually destroyed with the increase of the proportion of economic development in the development scenario;the connection mode between some ecological patches was changed;and indicators such as network connectivity, coreness, and average number of node connections of networks showed a decreasing trend. It was found that the network density was increased slightly in the (0.9, 0.1) mode, while it was gradually decreased in other scenarios with the increase of proportion of economic development. Moreover, in the (0.9, 0.1) mode, although the destruction occurred at the edge of the desert, the FG econetwork within the sample circle was expanded. The economic development did not necessarily lead to the deterioration of the ecological environment in this area. Under the existing natural conditions, the study area still had room for economic development, but the space was limited. Finally, totally 36 key ecological nodes were extracted, and the skeleton corridors of the study area were identified as 1236.89km. The study proposed to strengthen the key construction and protection of ecological construction of key ecological nodes and skeleton corridors, and implement stricter ecological management and control measures.

Abstract:Agriculture is directly related to human survival. The stability and sustainability of agricultural yields is the key to agricultural development. Climate factors not only provide material and energy basis for crops, but also restrict the effective implementation of agricultural technology. Taking maize as the main research object, based on the longterm meteorological observation data in Heilongjiang Province, the MannKendall analysis method was used to calculate the variation trend of precipitation and temperature in maize growth stage. The variation characteristics of precipitation and temperature (maximum, average and minimum temperatures) in maize growing season were revealed. And the principal component analysis (PCA) was combined with the standardized precipitation evaporation index (SPEI), the characteristics of regional drywet changes in the corn growing season of Heilongjiang Province were revealed. The results indicated that the changing trend of precipitation in Heilongjiang Province was not significant, but the changing trend of maximum temperature, average temperature and minimum temperature was significant. The changing trend of wetting was mainly concentrated in the northwest and southeast of Heilongjiang Province. The changing trend of drought was mainly concentrated in most areas of Heilongjiang Province from east to west. The meteorological production of maize was mainly affected by SPEI3-8. Dry and wet conditions SPEI3-8 in June-August were the main factors affecting maize yield. Compared with precipitation, temperature was the main factor affecting the yield of maize in the growth period of Heilongjiang Province. It provided reference for rational planning of regional water resources and optimizing agricultural planting structure.

Abstract:In order to accurately evaluate the dynamic changes and distribution in water consumption quantity and efficiency of crop production at different spatial and temporal scales in a region, the AquaCrop model was applied at 5′ spatial resolution to estimate the blue and green water footprints (WFs) of wheat production in three typical hydrological typical years in Yellow River Basin (YRB). Irrigated and rainfed wheat were identified. Results showed that the annual average total WF and perunitproduct WF of wheat in YRB were 2.19×1010m3 and 1.22m3/kg, respectively. Blue WF accounted for 65% of the perunitproduct WF of wheat. The wheat WF was decreased from the upper reach to the lower reach in YRB. Traditional surface irrigation dominated the total blue WF and total green WF of wheat by occupying 92% and 50% of basin’s total amount, respectively. The WF under irrigated condition was 1.40m3/kg, which was higher than that under rainfed condition of 1.12m3/kg. The WF of wheat production in YRB was affected by irrigation methods. The basin average WF under micro irrigation was only 1.67m3/kg, while that of sprinkler irrigation was up to 2.07m3/kg. The result indicated that the effects of different water supply and irrigation methods on large-scale WF accounting can not be ignored. The quantification and evaluation of crop WF distinguishing different water supply and irrigation methods could be an important foundation for efficient utilization of agricultural water resources. The results can provide reference for WF accounting and regional agricultural water saving strategy formulated for different temporal and spatial scales.

Abstract:In order to explore the effects of different water and nitrogen application amounts on tomato growth and nutrient uptake, pot experiment was carried out in greenhouse, where treated tomatoes were taken as research object. The irrigation was resumed when soil moisture was reduced to 50%, 65% and 80% of field capacity, and three irrigation levels were therefore designed named as I1, I2 and I3, respectively. Each irrigation level was associated with four nitrogen application rates （Ratio of N to soil quality was 0g/kg, 0.13g/kg, 0.27g/kg and 0.40g/kg named as N0, N1, N2 and N3, respectively）. The tomatoes growth, biomass, tissue water content and nutrient accumulation were measured in each treatment. The results showed that the leaf area per plant, stem diameter and plant height were significantly increased with the increase of irrigation amount, and increased first and then decreased with the increase of nitrogen application amount. The optimal growth index was obtained in N1 treatment for each irrigation level. There was no obvious regularity of stem and leaf water content among all treatments. However, increasing irrigation amount significantly improved fruit water content, while increasing nitrogen application amount significantly reduced it. The dry matter content of stems, leaves and fruits were increased firstly and then decreased with the increase of nitrogen application amount, and increased significantly with the increase of irrigation amount. Especially, N1 was the most conducive to dry matter formation. The plant tissues could absorb more total nitrogen（N）, phosphorus（P） and potassium （K）when increasing nitrogen application amount under water stress (I1) condition, which benefitted plant reproductive growth. The optimal nitrogen application amount for nutrient uptake by tissues was 0.13g/kg (N1). The accumulated N, P and K of above ground tissues was positively correlated with dry matter and negatively with corresponding nutrient concentrations (except N and K), but not with tissues’ water content. The accumulated N was positively related to accumulated P and K, thus, increasing nitrogen application amount could promote nutrient uptake of tomatoes, especially K uptake. In comparison with N1I3 treatment, the fruit dry matter，nitrogen accumulation and potassium accumulation of N1I2 treatment was decreased by 3.04%, 10.67% and 12.08%, respectively, but the irrigation amount was saved by 25%. The results revealed that the irrigation resumed at 65% of field capacity (I2) associated with 0.13g/kg (N1) was the optimal water-nitrogen combination treatment, which can save water and fertilizer, as well as regulate plant type, and lay the foundation for improving yield and quality.

Abstract:In order to make clear the regulation effects of irrigation timing on water consumption and yield of wheat under limited water supply during spring growing season, a field experiment was conducted in the test station of Dryland Farming Institute, Hebei Academy of Agricultural and Forestry Sciences during 2013 to 2017. Winter wheat cultivar, Heng 4399, was used. The measurements were taken on irrigation timing for six treatments, jointing 0d (AJ0), 5d after jointing (AJ5), 10d after jointing (AJ10), 15d after jointing (AJ15), 20d after jointing (AJ20), and 30d after jointing (AJ30). Irrigation amount was 75mm. Irrigation was synchronized with topdressing. The results showed that evapotranspiration of different treatments was ranged within 361.1~505.8mm and grain yield was ranged within 6620.4~8650.5kg/hm2.Compared different treatments, with irrigation time delayed, evapotranspiration and yield were increased first and then decreased. The three indicators, transfer amount of dry matter before anthesis, transport rate and contribution rate to grains before anthesis, all increased with lapse of treatment time, and reached the peak between 5d and 15d after jointing, and then decreased. Transfer amount of dry matter in vegetative organs after anthesis, AJ10 and AJ15 were higher than other treatments, AJ0 was the lowest. The contribution rate of afteranthesis assimilated to grains was more than 60% and was the main component of grain yield. WUE was ranged within 1.32~2.54kg/m3 which was affected by both the yield and evapotranspiration. WUE of AJ0 was the best treatment except 2017. Treatments with higher evapotranspiration was also higher in its grain yield. Evapotranspiration and grain yield were positively correlated with soil water supply amount. These results indicated that irrigation between 10.d and 15d after jointing, could not only sufficiently use soil water storage, but also improve grain yield of wheat.

Abstract:In order to explore the persistence of the effects of biochar application on soil moisture and infiltration performance in black soil areas, biochar applied with 75t/hm2 (BC) and without biochar (CK) were carried out for three consecutive years from 2016 to 2018. The indoor and outdoor comparative tests of biochar treatment were carried out to analyze the soil moisture content of various soil layers and the process of soil water infiltration. The results showed that biochar application could make the soil moisture content of each soil layers increase and the extreme value ratio Ka and variation coefficient Cv decrease. And the variation of soil moisture content, Ka and Cv was getting decreased with the increase of biochar application period. From 2016 to 2018, the soil moisture content of the cultivated layer was increased the most, which was increased by 14.54%, 11.48% and 7.08%, respectively. The biochar significantly increased the soil infiltration and soil infiltration rate, enhanced the soil infiltration capacity and promoted the migration of the wet peaks. The order of soil infiltration in the BC group from 2016 to 2018 was 2016, 2017 and 2018, and the initial infiltration rate f1 was increased by 70.48%, 58.98% and 48.41%. The stable infiltration rate fc was 2016 BC treatment (1.65mm/min), 2017 BC treatment (1.22mm/min), 2018 BC treatment (1.17mm/min), 2016 CK treatment (0.46mm/min),2017 CK treatment (0.43mm/min) and 2018 CK treatment (0.38mm/min). And the 2016 BC treatment humid peak was the deepest in 2016 to 2018 at 32.24mm. The indexes indicating that soil infiltration performance was the best in the year of biochar application and then weakened year by year. The soil infiltration amount had a good power function relationship with time. The wet peak migration distance and time had a good cubic function relationship, R2 was between 0963 and 0998. Comparing the fitting results of three infiltration models of Philip, Kostiakov and Horton models, Kostiakov model had the highest R2 value (0.946~0.991) and the smallest RMSE (0.516~1.941mm/min). There was no phenomenon that the fitting parameters were inconsistent with the actual situation, also. In the case of this study, the soil water infiltration process was optimal by Kostiakov model. The results provided a theoretical basis for improving the soil water infiltration process after applying biochar in the black soil region of Northeast China.

Abstract:In order to promote the growth of sunflower and improve the yield and water use efficiency of sunflower, five irrigation quotas were set. The five treatments were 300m3/hm2, 375m3/hm2, 450m3/hm2, 525m3/hm2 and 600m3/hm2, respectively. The effects of different irrigation quotas on plant height, leaf number, disk diameter and stem diameter of edible sunflower were analyzed and compared. The relationship between growth index of edible sunflower and yield and water consumption under different irrigation quotas was explained. The ability (potential) of different irrigation quotas to increase yield and water use efficiency of edible sunflower was analyzed by time series dynamic evaluation model. The results showed that the plant height, leaf number, disk diameter and stem diameter of sunflower were increased with the increase of irrigation quota. The treatments with 525m3/hm2 and 600m3/hm2 irrigation quota promoted the growth of sunflower growth index significantly. When the irrigation quota was increased to 600m3/hm2, the stem diameter of sunflower was not increased but decreased, and 300m3/hm2 irrigation quota limited the growth of sunflower plants. High irrigation quota was more conducive to the growth of plant height and leaf number of sunflower. There was a positive relationship between sunflower growth index and yield and water consumption. Water consumption and yield were increased with the growth of sunflower plants. Under 525m3/hm2 irrigation quota, sunflower plants grew well, consumed more water and had higher yield. Irrigation quota of 600m3/hm2 increased nutrient growth time and water consumption of sunflower, which was not conducive to yield increase of sunflower. In reproductive growth stage, the water consumption of sunflower under 525m3/hm2 and 600m3/hm2 irrigation quota was high, and the reduction of plant height and stem diameter was large. The evaluation results showed that the comprehensive growth of sunflower under 300m3/hm2 irrigation quota was at a disadvantage, and the ability to improve yield and water use efficiency was weak, that was, the potential was small. The sunflower under 525m3/hm2irrigation quota had the best comprehensive growth potential. The 525m3/hm2 irrigation quota was suitable for the actual sunflower irrigation system. The time series dynamic evaluation model can better solve the problem of field test evaluation, and provide a reference for comprehensive analysis of field test based on dynamic and static indicators. 

Abstract:A field experiment was carried out to study the effects of different water and phosphorus managements on dry matter accumulation, phosphorus uptake and utilization, yield of rice at the maturity stage in cold black soil region, the relationship between root traits and phosphorus uptake efficiency at heading stage was discussed. Two irrigation modes (F: flood irrigation, C: controlled irrigation) and six phosphorus application levels (P0:0kg/hm2,P1:15kg/hm2,P2:30kg/hm2,P3:45kg/hm2,P4:60kg/hm2,P5:75kg/hm2) were set, the effect of different water and phosphorus managements on aboveground dry matter, yield and its components, phosphorus accumulation in grains and plants, phosphorus use efficiency, phosphorus uptake efficiency and phosphorus fertilizer partial productivity were studied. The results showed that under two irrigation modes, with the increase of phosphorus application rates, the aboveground dry matter, yield, effective panicle number, seed setting percentage, phosphorus accumulation in grains and plants were increased firstly and then decreased, and harvest index, phosphorus harvest index, phosphorus use efficiency of grain and dry matter were decreased firstly and then increased, however, the phosphorus uptake efficiency and phosphorus fertilizer partial productivity were decreased. The aboveground dry matter, yield, effective panicle number, seed setting percentage, phosphorus accumulation in grains and plants of CP2 and FP3 reached the maximum, respectively, among the different water and phosphorus treatments. There was no significant difference in yield between CP2 and FP3 (P>0.05), however, the phosphorus fertilizer partial productivity of CP2 was significantly higher than that of FP3(P<0.05). Therefore, CP2 treatment was the best water and phosphorus management in this experiment. The correlation analysis showed that there was a positive correlation between yield and aboveground dry matter (P<0.01) and a significant negative correlation between yield and harvest index (P<0.05). Plant phosphorus accumulation was positively correlated with aboveground dry matter (P<0.01). Plant phosphorus accumulation was positively correlated with root dry weight and root length density (P<0.05). The results indicated that suitable water and phosphorus management could create good root morphology, increase dry matter accumulation, which was more conducive to improving yield and phosphorus use efficiency. The research results provided theoretical basis for understanding the difference of rice root morphology and phosphorus fertilizer utilization under different water and phosphorus managements and guiding the practice of high yield and high efficiency cultivation of rice in cold black soil region. 

Abstract:A pond-based experiment with winter wheat cultivars (Triticum aestivum L.) was conducted under rainproof shelter during the growing seasons of 2016—2017 to investigate the effects of regulated deficit irrigation under alternate furrow irrigation on physio-biochemical characteristics and yield of winter wheat. Five experimental treatments were included, conventional border irrigation (T1, the soil water content in planned moisture layer was controlled at 65%~75% field capacity (FC ) throughout growing season), alternate furrow irrigation (T2, two root-zones were alternatively irrigated during the consecutive irrigation, the soil water content with values of (55%~65%)FC and 95% FC were considered as the lower limit and the upper limit for irrigation, respectively), T3, T4 and T5 were defined as alternative furrowregulated deficit irrigation (the soil water content in planned moisture layer was controlled at (55%~65%)FC at the beginning of returning greenstem elongation, stem elongationear emergence, and ear emergencematurity period), respectively. When the soil water content at the soil layer of a given treatment fell below the lower limit of the target range during the waterdeficit treatment period, it was replenished to 95% FC. Three treatments (T3, T4 and T5) received irrigation water at the T2 level during the unstressed stages. The photosynthetic characteristics, proline and soluble sugar content of flag leaf after anthesis and wheat yield components and so on were measured. The results indicated that the net photosynthetic rate and transpiration rate of the border irrigation were higher than those of alternate furrow irrigation and alternate furrowregulated deficit irrigation treatments, butthe higher leaf water use efficiency under the alternate furrow irrigation was demonstrated. Alternate furrow irrigation treatment and alternate furrowregulated deficit irrigation treatments had a lower yield than that of the border irrigation, but it didn’t reach a significant level (P>0.05) for T1 and T2. The yields of T2 and T3 were decreased by an average of 1.98% (P>0.05) and 568% (P<0.05) respectively, but their water consumptions were decreased by an average of 1001% (P<0.01) and 16.91% (P<0.01) respectively, and their WUE were increased by 9.04% (P<0.05) and 15.82% (P<0.01) respectively. The present results suggested that alternate furrow-regulated deficit irrigation applying suitable water deficit （55%~65%）FC during returning green stage under alternate furrow irrigation was the better irrigation model to save water and achieve high grain yield in winter wheat.

Abstract:The facility light environment, including facility light intensity and light quality, is an important factor affecting the growth and development of crops. There is a significant interaction between the light intensity, light quality and photosynthetic rate at different temperatures. It is one of the most urgent problems for facility agriculture to establish an intelligent regulation model of light environment for facility cucumbers with light quality demand, and effectively improve the light environment of crops. A multifactor nesting experiment was designed to obtain multidimensional sample data, and a support vector regression algorithm photosynthetic rate prediction model was constructed, which coupled temperature, light intensity, and light quality. Then, based on the particle swarm optimization algorithm, the optimal light intensities and light qualities under specific temperature conditions were obtained quickly. Finally, based on the optimization results, the intelligent regulation models of red and blue light were constructed by partial least squares regression method. As a result, the fitting degrees of training set and test set of the photosynthetic rate prediction model were 0.9971 and 0.9969, respectively, and the root mean square errors of training set and test set were 0.3630μmol/(m2·s) and 0.4367μmol/(m2·s).The root mean square errors of the intelligent regulation models of red and blue light were 15.0878μmol/(m2·s) and 10.1383μmol/(m2·s), respectively. Compared with the traditional fixed light quality models, the regulation effect of the model was significantly improved, which indicated that these models provided an important basis for the effective regulation of the light environment of facilities.

Abstract:CO2 is one of the main resources for plant photosynthesis. The slope of CO2 response curve represents the effect of CO2 concentration on photosynthetic rate. The first curvature maximum point represents the characteristic point where the effect of CO2 concentration on photosynthetic rate becomes weak. Therefore, the acquisition of this point is the key to realize the optimal benefit control of CO2. A CO2 optimal control model based on discrete curvature algorithm was proposed. Firstly, a photosynthetic rate experiment was designed. The subject of the experiment was tomato. The experimental conditions were the different combinations of temperature, photonic flux density and CO2 concentration. In the experiment, temperature, photon flux density and CO2 concentration gradients were set as 6, 10 and 20, respectively. Totally 1200 sets of CO2 response data were obtained by LI-6800 portable photosynthetic rate instrument. And 80% data were used to construct photosynthetic rate prediction model based on the support vector regression, and the rest of the data were used for model verification. Then, the CO2 response curves under the nested conditions were obtained by using the established photosynthetic rate prediction model. Next, the discrete curvature value of every response curve was calculated by the L-chord discrete curvature algorithm. Using hill-climbing method, the maximum curvature value of every response curve was obtained. The CO2 concentrations corresponding to the maximum curvature values were taken as the control target values. Finally, the CO2 optimal control model was constructed based on the support vector regression. The results showed that the decision coefficient of the control model was 0.99, the mean square error was 4.42μmol/mol, and the average absolute error was 3.17μmol/mol. Compared with the CO2 saturation point, the CO2 demand was decreased by 61.81%, but the photosynthetic rate was decreased by 15.58%. In the verification experiment, compared with the saturation point regulation, the average photosynthetic rate was decreased by 15.14% by using the proposed regulation method, the supply of CO2 was decreased by 57.61%. Compared with the natural method without any regulation, the photosynthetic rate was increased by 26.70% with the regulation proposed method. This indicated that the CO2 optimization control model was of high efficiency and energy saving. This control model could provide theoretical basis for efficient and precise regulation of CO2 for facility crops.

Abstract:Aquatic products have high economic benefits and are prone to spoilage, which is mainly related to enzyme activity in the body, and temperature is an important reason for affecting enzyme activity. Among them, live aquatic products require higher temperature stability. Thus how to maintain uniform temperature in refrigerated compartments and ensure the quality of aquatic products has become an important research topic, in which the way of goods stacking is an important research direction. The distribution of temperature field inside the carriage of the refrigerated aquatic products with upper air outlet and upper air return was simulated by using Fluent module in ANSYS 16.0. The temperature cloud diagrams of the surface, cross section and longitudinal section of the cargo under the refrigeration device were compared with those under the four stacking modes, which were 0m, 0.533m (H/3), 1.066m (2H/3) and 1.6m (H). The results showed that the temperature distribution was in the form of inverted “ C ” along the length direction of the carriage, that was, the area near the lower part and the rear lower part of the carriage was higher;the goods stacked under the refrigeration device would have a significant impact on the uniformity of the temperature distribution. In the case of stacking mode a when the stack height was 0m, the temperature distribution was more uniform, the temperature in the cargo area was within 5℃, and the maximum temperature difference was 2℃. Comparing the experimental results with the simulation results, the maximum root mean square error of the two results was less than 0.5℃, and the maximum average relative error was 7%. Test results and simulation results showed good continuity. The general law of temperature field distribution in refrigerated aquatic products transport carriage was obtained, which had a certain degree of practical guiding significance for the cargo layout and structure optimization of aquatic products transport vehicle.

Abstract:In order to explore the demulsification mechanism of soybean oil emulsion produced by aqueous enzymatic method, the effects of jet cavitation pressure, jet cavitation temperature and jet cavitation time on the demulsification mechanism of soybean oil emulsion were investigated by light scattering particle size analysis, demulsification rate, total oil extraction rate and emulsion microstructure. The results showed that the demulsification rate and total oil extraction rate were increased with the increase of jet cavitation pressure (0.2~1.0MPa), jet cavitation temperature (80~120℃) and jet cavitation time (5~25s). After the complete demulsification, the demulsification rate and total oil extraction rate were decreased. The particle size distribution of emulsion and laser confocal microscopy showed that the dispersed small size oil droplets were changed into larger diameter oil droplets after demulsification. On the basis of single factor experiment, response surface methodology was used to optimize the process conditions of jet cavitation assisted hydrolysis demulsification. The optimum demulsification conditions were determined as follows: jet cavitation pressure was 0.8MPa, jet cavitation temperature was 100.92℃, jet cavitation time was 21.38s. Under this condition, the demulsification rate was 90.29%, and the total oil extraction rate was 87.06%. The research result provided a theoretical basis for jet cavitation assisted enzymatic demulsification technology, and it was beneficial to the industrial application and promotion of aqueous enzymatic oil extraction technology.

Abstract:The emulsion and hydrolysate obtained from enzymatic hydrolysis of Jatropha curcas L. seeds were used as compound emulsifier, and the enzymatic hydrolysate nanoemulsion of Jatropha curcas L. seeds was prepared by high pressure homogenization technology. The effects of additive amount of emulsion and hydrolysate in the enzymatic product of Jatropha curcas L. seeds, as well as high pressure homogenization pressure and frequency on the average particle size, polydispersity index (PDI),ζ-potential, turbidity, emulsion productive rate and TSI of nanoemulsion were studied, results with the highest desirability of preparing the nanoemulsion were obtained with the additive amount of emulsion at 15.55%, the additive amount of hydrolysate at 45.25%, high pressure homogenization pressure at 91MPa and homogenization frequency at four times. Upon these conditions, the average particle size was 297.2nm, turbiscan stability index (TSI) was 2.98 and the emulsion productive rate was as high as 92.47%. The enzymatic hydrolysate nanoemulsion of Jatropha curcas L. seeds was finally prepared, it was observed through the super highresolution microscopy that the particles of it were uniform in the size and evenly distributed in the emulsion system. In addition, it was found that the interfacial protein content of the nanoemulsion was as high as 31.20mg/m2.

Abstract:The process of extraction soy protein isolate from highly denatured soybean meal by alkali lytic acid precipitation method with the aid of jet cavitation was aimed to increase the yield of protein. The effects of different jet cavitation powers（0~2.0MPa）on soy protein isolate extraction rate, secondary structure, oilholding capacity and water holding capacity, solubility, foaming and emulsifying properties were further studied. As the results shown, the free sulfhydryl contents and the surface hydrophobicity of the samples treated by jet cavitation were significantly higher than those of the untreated samples (P<0.05), while the disulfide bond contents were significantly decreased (P<0.05). When the jet cavitation power was 1.5MPa, the extraction rate of soy protein isolate was 58.97%, which was 34.42% more than the untreated sample. The oilholding capacity and water holding capacity, solubility, foaming and emulsifying properties of soy protein isolate were significantly improved. The results indicated that the jet cavitation treatment unfolded the protein molecules, stretched the structure, exposed more free sulfhydryl groups, decreased the particle size of the protein particles, and increased the specific surface area, which was beneficial to improve the functional properties of soy protein isolate. When the jet cavitation pressure was increased to 2.0MPa, the high pressure and extreme heat decreased the functional properties of soy protein isolate. At the same time, the functional properties of the extracted soy protein isolate and commercial soy protein isolate were compared, the results characterized the jet cavitation process in improving the utilization value of protein in high temperature soybean meal.

Abstract:The distribution of grain in the flight elevator is an important factor affecting the grain mass flow measurement error of photoelectric sensors. To improve the grain mass flow measurement accuracy of combine harvester, a grain thickness measurement method based on infrared photoelectric effect was proposed. The sensor was mainly composed of laser emitter, silicon photocell and signal processing circuit. The nearinfrared light with wavelength of 850~980nm was generated by using the laser emitter, and the light intensity passed through the grain was received by using the silicon photocell. Then, the grain thickness can be acquired according to the variation of received light intensity. An I/V conversion circuit based on T-type feedback network was designed. The Gaussian regression equation was established to describe the relationship between the output voltage and the grain thickness. The effects of laser emitter power, infrared wavelength and rice variety on the sensor measurement performance were analyzed. The results showed that the optimal regression accuracy was received with the infrared wavelength of 940nm, and the measurement error of grain thickness was less than 0.5mm. The measurement range was increased with the increase of laser emitter power. The effective measurement range of about 50mm could be achieved when the power was 500mW. The transmission capacity of infrared ray to grain was increased with the increase of wavelength and decreased with the decrease of grain moisture content. The proposed measurement method and sensor of grain thickness can be used to measure the time interval which grain blocked the light path during the lifting process, and also can be used to analyze the grain distribution in the flight elevator. The research result provided important reference for improving the grain flow measurement accuracy.

Abstract:Electrode structure is an important factor affecting the charging effect of droplets. To study the effect of structure of ring electrode on the performance of electrospray, totally 12 kinds of ring electrodes based on the combination of different inner diameters (12mm,14mm, 16mm and 18mm) and thicknesses (1mm, 2mm and 3mm) were selected for experiments. In the experiment, the digital SLR camera was used for image acquisition, and the image was processed by software to obtain the spray cone angle. In the experiments, the voltage across the resistor was directly measured, and the droplet charge-mass-ratio was obtained by calculation. The effects of electrode structure on droplet charge performance and spray morphology were analyzed by comparing the spray cone angle and the droplet charge-mass-ratio. Based on the experimental condition, electric field of different ring electrode structures was calculated by numerically simulation, and its influence on the electric field distribution was obtained. The results showed that as the inner diameter of the ring electrode decreased or the thickness increased, the radial electric field strength around the ring electrode was increased, and the axial electric field strength did not change significantly. The spray cone angle and the specific ratio were increased as the inner diameter of the ring electrode decreased or the thickness increased. The variation of the thickness and inner diameter of the ring electrode changed the spatial electric field distribution, which affected the spray structure and droplet charging. The research results can supply some guideline for improving the charging performance of the droplets and rationally designing the electrostatic spray device.

Abstract:Path planning and decision-making algorithm is one of the most important research directions of driverless vehicles. However, the delays of the path planning and decision-making algorithms could lead to the inconsistency between sensor information and real driving environment, introducing negative effects on the ability to avoid dangerous state. Classified longitudinal model was established by considering the expected route, kinematics characteristics of environmental traffic participants and vehicles to determine the safety condition of vehicle. Also, a lateral safety space model was established to determine whether it was safe to change lane. Based on the safety model, combining the environmental and vehicle dynamic characteristics, an integrated algorithm of local path planning and decision-making algorithm was provided to improve the performance of the algorithm in complex dynamic environment. In the model, the influence of environmental information was represented with artificial force such as global planning gravitation, lane changing gravitation, forward obstacle repulsion and sensor occluded scenes repulsion. Gravitations represented attractive factors’ influence and repulsions represented repulsive factors’ influence of environment. Finally, co-simulations based on Carsim/Simulink was established to analyze the delay of traditional algorithm and algorithm proposed under various typical conditions. Results showed that the proposed algorithm can reduce the time-delay effect of path planning and decision-making, and provide better control for unmanned vehicle control in complex dynamic environment.

Abstract:The theoretical dynamic model of ball screw feeding system was firstly established, and the characteristics of its response transfer function were analyzed. Then the integrated model of ball screw feeding drive system based on digital module simulation was constructed. The optimization method of ball screw feed drive dynamic performance based on the scalable control optimization model was proposed. The scalable dynamic characteristic index evaluation function for comprehensive performance estimation was constructed. The dynamic performance evaluation index function can be established in real time according to the requirement of dynamic performance optimization. Based on the above, with the definition of motion path planning, by the genetic optimization algorithm, the dynamic performance optimization of ball screw feed drive system oriented to scalable comprehensive index evaluation was realized finally. By experimental test and case analysis, the validity of the theoretical dynamic modeling of ball screw feeding system and its analysis conclusion, integrated model of ball screw feeding drive system based on digital module simulation, and also dynamic performance optimization method based on the scalable control optimization model were verified. The method provided a reference for dynamic performance optimization of ball screw feed system.

Abstract:According to the different operating environment and working conditions, the collision can be divided into unconstrained collision and constrained collision, including immovablepoint collision and movablepoint collision. Firstly, the impact dynamics model of the serial robot system was established based on Lagrange equation, and the solving model of external impulse was derived from classical collision theory and recovery coefficient equation. Secondly, with respect to unconstrained collision, the concept of impact motion mapping matrix was proposed on the basis of impact dynamics analysis, and the evaluation index named impact motion performance was constructed for evaluating the ability to maintain motion stability under external impulse action. Finally, the ideas and methods for solving problems of immovablepoint collision and movable-point collision in kinematically redundant serial robot were transformed into optimizing robot’s pre-collision posture by choosing the minimum external impulse generated during the collision as the objective for optimization. Taking the planar threebar robot as an example, the impact motion analysis and optimization design of unconstrained collision and constrained collision were carried out respectively. The results showed that the external impulse would rise significantly when robot was in or near singularity, and its structural parameters had a great effect on the impact motion performance. The external impulse generated from collision can be reduced effectively by means of pre-collision posture optimization, which was very useful for improving the stability and security of the system.

Abstract:Different from the existing methods by using constraint singularity or the chain singularity to synthesis metamorphic parallel mechanisms, an actuated metamorphic parallel spherical joint of full rotation of the one-dimensional, two-dimensional and three-dimensional rotation by way of opening and locking actuated kinematic pair was presented through the method of finite screw. Using the screw theory, the degree freedom of three configurations of the actuated metamorphic parallel spherical joint was analyzed, the mechanism kinematics was studied according to the structure characteristics and geometric constraints of the actuated metamorphic parallel spherical joint. Finally, SmPU actuated metamorphic chain was obtained according to integrating the actuated metamorphic parallel spherical joint (Sm) with P kinematic pair and U kinematic pair serial limb. Based on the SmPU actuated metamorphic chain, 3-SPS/SmPU actuated metamorphic parallel mechanism of six motion modes was presented. The method of the type synthesis actuated metamorphic parallel spherical joint can also be applied to type synthesis other actuated metamorphic parallel joints, the metamorphic method was simple and effective, and constraint singularity and the chain singularity could be avoided effectively in the metamorphic process.