Abstract:Chemical fertilizer is one of the basic materials in modern agricultural production. It has important significance to the development of grain production safety and high-efficiency agriculture. The problems of agricultural safety production, environmental pollution and cost wastage are increasingly prominent which were caused by long-term blindly excessive application of chemical fertilizers in China. How to effectively balance the relation among grain production, ecological security and chemical fertilizer reduction has become a system engineering problem that must be faced. Considering the requirements for application of scientific fertilization technology, the present situation of chemical fertilizer application in China was illustrated and evaluated. The research progresses, technical features, application statuses and existing problems of modern fertilization technologies were analyzed, such as soil testing and formulated fertilization, slow/controlled release fertilization, precision variable-rate fertilization, irrigation and fertilization, and fertilization for staple crop. Finally, the trends of government policy, technology research and promotion training were expected clearly based on the requirement of sustainable agricultural development, which provided ideas for constructing a scientific fertilization technology and management system with the Chinese national condition and references for related research.

Abstract:Precise path control of unmanned aerial vehicle (UAV) is the key technology to realize aviation plant protection in mountain orchards. In order to carry out the plant protection operation stably and accurately in mountain orchards, based on the four-rotor UAV, the flight path control system and method of UAV for plant protection by fusing GNSS and machine vision were designed. The system consisted of two parts, i.e., UAV flight platform and ground control station. The former consisted of a four-rotor UAV, an inner-ring flight control module, a GNSS moving station, a RGB camera, a wireless video transmission module and an electronic compass. The latter consisted of a GNSS base station, a flight control module, a laptop and a video capture module. A fruit tree row recognition algorithm was proposed based on Python language combined with OpenCV library. In this algorithm, a linear combinatorial algorithm was used to extract the target area, and the least squares method was used to fit the central point of target area to obtain the row trend of fruit tree. Then the yaw angle was calculated to realize the path control. In the working process, the UAV was controlled by the visual navigation method when flying over the fruit tree, while controlled by the GNSS navigation method when it needed to switch between rows of different operation fruit trees. The developed system and proposed method was tested in mountain apple orchard. The results showed that when the flight speed was 2m/s, the height of UAV from fruit tree canopy was about 2m, the camera’s dip angle was 46° and the image navigation control rate was 2 times/s, the absolute path control error of the system was -47~42cm, and the average absolute error was -9cm. The high control precision indicated that the system could meet the requirements of UAV for plant protection operation in mountain orchards. The research provided a new method for path control of UAV on plant protection in mountain orchards.

Abstract:Reliable pedestrian detection in agriculture field is one of the key technologies for unmanned agricultural vehicles. For the complex environment in the orchard, it is difficult to accurately detect the obstacle information. To solve this problem, an improved single shot multibox detector (SSD) deep learning object detection method was proposed to detect pedestrian in the field obstacles. The lightweight network framework MobileNetV2 was used as the basic network in the SSD model to reduce the time and computational effort of extracting image features. For auxiliary layer of the SSD model, the inverse residual block combined with the dilated convolution was used as the basic structure for position prediction so that the multi-scale features can be integrated and at the same time avoiding the information loss caused by the down sampling operation. Based on the Tensorflow deep learning framework, different motion states (motion and static), different pose states (normal and unnormal) and different object scales (large, medium and small) pedestrian detection experiment in orchard were carried out on the open data set in orchard environment of the National Robotics Engineering Center of Carnegie Mellon University and the accuracy and speed of these different situations were compared. Result showed that the average precision and recall rate of the improved SSD pedestrian detection model in agriculture reached 97.46% and 91.65%, respectively, higher than 96.87% and 88.51% of the original SSD model, and the parameter quantity was decreased by seven times. The speed was accelerated by three times and the detection speed was 62.50 frames per second. The model had good robustness and could detect the pedestrian in the field environment, which could provide a basis for the obstacle avoidance of the unmanned agriculture machinery.

Abstract:Wheat rust has a great harm to wheat production in worldwide. The rapid monitoring and classification of wheat rust is the basis for scientific production and management, and it is also the prerequisite to realize the treatment of wheat rust as soon as possible. In view of the shortcomings of conventional image detection algorithms, a fast detection and classification method based on infrared thermal imaging technology was proposed. Wheat samples were planted in a growth chamber at the University of Alberta, Canada. Growth chamber parameters settings were as following: temperature (max 15℃, min 11℃), photoperiod (day 12h), light intensity (10000lx), RH (60%~70%). The spring wheat variety (Peace) was susceptible to rust. The infrared thermal imager brand was FLIR E6, USA. Thermal sensitivity was less than 006℃;FOV was less than 45°ohorizontal×34°overtical;IFOV was 5.2×10-3 rad;IR was 160 pixels×120 pixels. The infrared thermal imaging of the whole wheat samples were collected to calculate the average leaf temperature of the healthy plants, the submersible plants and the symptomatic plants, and the temperature changes during the invasion of the fungi were detected. Infrared thermography can be used to detect leaf temperature drop caused by pathogen infection at 6d of pathogen infection incubation period, which was 7d ahead of the naked eye observation of leaf rust spores. The Prewitt operator (PO), Sobel operator (SO), Canny operator (CO) and Laplacian operator (LO) were used to extract the edges of visible light images. The edge extraction results of PO and SO on the lesion area was not satisfactory for the complex noise processing, and the boundary gray area was seriously ghosting. LO and CO were too lean for the edges, the detection accuracy was reduced, and the background error was too large. Obviously, the direct use of conventional edge detection operators cannot meet the ultimate goal of rapid classification of diseases. Therefore, a fast detection and classification method based on infrared thermal imaging technology was proposed. The experiment was divided into two kinds of extraction methods: single leaf and whole plant. When the whole plant was extracted, the flower pot was removed and only the wheat plant was kept for extraction. From the results of the whole wheat extraction, the area of the whole plant disease can be extracted successfully by the method of area occupation ratio calculation based on the temperature edge. The error of the regional extraction results of the single leaf focus was slightly larger than that of the single leaf focus, but the final calculation results were satisfactory. The region below the temperature threshold was extracted from the infrared thermal image which was preprocessed by histogram equalization and median filtering. The ratio of lesion area to total area of plant thermography was calculated after three steps, including temperature division, low temperature region extraction and threshold segmentation. Finally, the correlation analysis was carried out with the disease index. The correlation coefficient was 0.9755, the root mean square error was 9.79%, and the overall recognition rate was 90%. The research result showed that the wheat leaf rust classification method based on the infrared thermal imaging temperature information was feasible. It provided the theoretical and method basis for the early scientific application and the establishment of more accurate disease identification expert system.

Abstract:Collecting airborne spores of rice blast in rice fields using spore trap devices has currently become an important approach for devising strategies early and effectively controlling rice blast. In order to solve the problems of large volume and high cost of existing spore detection system, a spore detection method for crop fungal diseases was proposed based on diffraction reconstruction technology. Based on Huygens-Fresnel principle and angular spectrum theory, a spore detection system for fungal diseases, including enrichment and sampling mechanism, was designed by using diffraction imaging complex reconstruction calculation. The system can complete a series of operations such as enrichment, sampling, shooting, reconstructing and detection, and reconstruct the original spore image of fungal diseases by reconstruction algorithm. According to the morphological characteristics of reconstructed images, two important parameters, area and thinness ratio, were extracted to detect and identify spores. Rice blast spores were selected as the research object to carry out detection and verification experiments. The experimental results showed that the system could capture the micro-images of diffractions of rice blast spores, with 2592 pixels×1944 pixels resolution. The experiments validated that the correlation coefficient between the detection results of rice blast spores and the identification results of artificial microscope can reach 0.99, while the average detection error rate was 5.91%, which had good accuracy. The research provided a design scheme for the research and development of low-cost early warning equipment for crop fungal diseases. 

Abstract:In order to deal with the problems of straw returning and soil tillage in multiple cropping rice regions of paddy-upland rotation in mid-lower Yangtze River, and reduce the power consumption and axial force of the existing interlaced-type rotary blade roller, a research about arrangement and structure parameters of the helical blades in combined cutter roller was conducted. Based on the theoretical analysis of the axial force of cutter roller, two arrangements for balancing axial forces were proposed and verified by discrete element software. The simulation results showed that the axial load stability and cutting resistance of herringbone arrangement were better than that of serrated and interlaced type. Based on the principle of herringbone type arrangement, the rotary blades ware rearranged and the supporting cutter plate was designed. In order to further reduce the power consumption of the cutter roller, the mathematical model of cutting soil with helical blades was established. Based on the mathematical model, the influence of installation angle and blade width on cutting resistance and straw burying effect was analyzed, and the optimization of the installation angle and blade width was carried out accordingly. Field tests were carried out to verify the applicability and drag reduction effect of the optimized cutter roller. The testing results showed that the optimized cutter roller was suitable for straw returning and soil tillage for most paddy fields, and the average tillage depth was 18.10cm, the stability of the tillage depth was 92.75%, the smoothness after tillage was 2.00cm, and the straw buried rate was 92.60%, which can all meet the design requirements. The results also showed that without reducing the straw buried rate, the power saving range of the herringbone-type rotary blade roller was 0.34%~17.01% compared with the interlaced-type rotary blade roller，and the power saving range of the blade roller assembling helical blades with 50° installation angle was 6.81%~16.46% compared with helical blades with 35° installation angle, which verified that the proposed blade roller can achieve the aim of optimization. The research result provided new technical equipment for the direct full amount of straw returning to the field.

Abstract:Crop straw non-burning and returning has become one of the most important moves for comprehensive realization of straw resource utilization. Aimed at problems of large quantity of straw stalks, difficult sowing of later crops, wrapped straw and high-power consumption by using traditional straw crushing-returning machine for rice and wheat rotation region in the middle and lower reaches of the Yangtze river, straw crushing and seed-belt classification machine under full straw mulching was developed in combination with the agronomic requirements of wheat seeding in rice-stubble field in Jiangsu Province. One trip to the field, it can complete the multiple operation processes of straw-stubble crushing, row-spacing stacking, seed-belt cleaning, and the follow-up seed bed treating, fertilizer sowing, soil covering and suppressing, etc. Key components such as straw pickup-chopping device, guide-adjusting device and transmission route system were designed and analyzed theoretically to determine the relevant structure and position parameters. Three-factor and three-level orthogonal performance test was carried out with setting rotation spindle speed n(A), guider radial distance τ(B) and machine ground speed v(C) as the influence factors, straw crushed rate ε1 and stubble cleaned rate ε2 as the evaluation indexes. It can be known from the orthogonal test that the importance order of the factors which affecting ε1 was A, C and B, and that affecting ε2 was B, C and A, the comprehensive choice optimum combination of working parameters was A2B2C2, that was n=2000r/min, τ=20mm,v=1.0m/s, and ε1=93.42%,ε2=92.71%, the machine reached the best working performance. Field validation tests under optimum parameter combination showed that the average ε1 and ε2 were 91.25% and 90.54%, respectively, which satisfied the technical standards and agronomy requirements. The research results can provide technical and equipment support for the realization of straw non-burning and fertilization utilization, which had considerable production and application prospects.

Abstract:Precise seeding technology has become an important direction of vegetable seeder development. Considering the characteristics of multi-varieties and large differences in vegetable seeds, the requirements for sowing are also different. According to the above practical problems，a pneumatic-sheave combined precision metering device was designed which owned advantages such as simple structure and suitable for various vegetable seeds. The precision metering device adopted a two-stage seeding mode. The small grooved wheel seeding device adopted for the first part, negative pressure to adsorb seeds and positive pressure to remove seeds were adopted for the second part. Three-dimensional laser scanning and three-dimensional point cloud calculation method were used to measure the three-axis size of pakchoi, radish and eggplant seeds. Based on these data, several shapes of suction nozzles such as through hole, conical hole, cylindrical hole and kidney ellipsoid hole were designed. The single-factor test was used to obtain the best chamber vacuum for seeder. By applying the single factor text for vacuum degree, optimal result showed that most suitable vacuum degrees for pakchoi, radish and eggplant were 4kPa, 5kPa and 3kPa, respectively. The optimal metering tray speed and suction nozzle type hole were obtained by the complete combination test. The result showed that when the rotational speed of the metering tray was 17.5~22.5r/min, the metering device qualified rate was high, especially at 20r/min. The suction nozzle type holes suitable for pakchoi, radish and eggplant were conical holes, kidney ellipsoid hole and through hole, respectively. Under the optimal suction nozzle, vacuum and rotational speed conditions, the qualified rates of pakchoi, radish and eggplant were 97.0%, 95.4% and 93.7%, respectively, which could completely meet the requirement of seeding index.

Abstract:In order to realize the real-time monitoring of the operation process of vegetable small seed electric seeder and improve the intelligent level of the small seed seeder, a small-grain seed electric seeder with detection function was designed by using photoelectric sensor with surface detection characteristics and visual sensor with image acquisition effect, which can complete the functions of seeding, missing seeding monitoring and seeding display, at the same time, monitoring the seeding situation and collection. The measured data can be stored and managed effectively, and the operation of the electric seeder can be analyzed later. The results showed that the accuracy rate of seeding quality monitoring system was more than 96%, the accuracy rate was over 92.3%. In the test of the image sensor, the monitoring accuracy was more than 95% when the seeding velocity was 3.0km/h and 4.5km/h, respectively. Visual Basic 6.0 software was used to equip the operation interface for the monitoring system. In the process of operation, the monitoring system can be controlled in real time, and the counting of seeding, missing seeding and real-time image of seeding can be displayed on the display screen. The research solved the problem that manual was difficult to monitor the sowing quality in real-time, and improved the sowing quality and work efficiency of the seeder.

Abstract:The 2BMFJ series of precision seeder for no-tillage mulch straw in stubble field developed by Northeast Agricultural University integrated seed bed preparation, stubble prevention, precision seeding, deep fertilization, covering and compacting soil, spraying potions, covering straw evenly and other functions, the original stubble field with high quality and precision seeding operations was completed. It has become an important technical means to ensure the combination of intensive cultivation and conservation tillage. In order to solve the problem of large amount of straw return during the operation of the spring-tooth cleaning plant, it was of great significance to study a kind of prevent bring back stubble mechanism. Therefore, based on the existing stubble no-tillage mulch straw precision seeder spring-tooth cleaning device, the prevent bring back stubble linkage mechanism was added. By modeling and analyzing the lateral throwing residual of the linkage mechanism, the change rule of rear deviation angle in the direction of outer normal line of the pulley was determined. The minimum rotational speed of the drive pulley was obtained by theoretical analysis of the stubble conveying with spring-tooth. Based on the theoretical analysis of soil cutting length, the structural parameters between the spring-tooth were obtained. In order to obtain rules of the spring-tooth on the residual stubble, the structural parameters of the prevent bring back stubble linkage mechanism were determined. The experiment was carried out by using the method of L9(34) orthogonal test. The working speed, deflection of springtooth and rotational speed of drive pulley were selected. The rate of straw removal and the rate of straw return were taken as the evaluation indexes. The results showed that the working speed and the rotational speed of drive pulley had an extreme significant effect on the straw removal rate of seed bed (P<0.01). The effect of the angle on the straw return rate was significant (0.01

Abstract:Based on the design concept of 2BMFJ series no-tillage precision planter, which is light weight and uniform in sowing depth, a two-degree-of-freedom combined profiling no-tillage precision drill unit was designed. Based on Lagrange equation, a mathematical model of ditching depth of precision drill unit was established, and the key structure and working parameters affecting the ditching depth were determined. The autumn untreated maize stubble field was selected as the test plot. Four-factor and five-level quadratic regression orthogonal rotation center combination test method was applied, experimental optimization on structure and working parameters affecting the performance of precision drill unit was done, and the initial increment of spring, initial traction angle, spring stiffness and working speed were selected as influencing factors. The qualified rate of ditching depth, soil hardness and variation coefficient of ditching depth were selected as evaluation indexes, the primary and secondary relations of factors affecting the qualified rate of ditching depth were obtained as follows: spring stiffness, working speed, initial increment of spring and initial traction angle, the primary and secondary order of factors affecting qualified rate of soil hardness were as follows: spring stiffness, working speed, initial traction angle and initial increment of spring，and the primary and secondary order of the factors affecting the variation coefficient of ditching depth were follows: initial traction angle, working speed, spring stiffness and initial increment of spring. Design-Expert 6.0.10 software was used to establish regression equation, significance and optimization parameters of the test data were tested, the results showed that under the conditions of initial traction angle of 0°, spring stiffness of 10N/mm, initial spring increment of 15～19.5mm and working speed of 6.7～7.8km/h, the qualified rate of ditching depth was more than 95%, the qualified rate of soil hardness was more than 95%，and the variation coefficient of ditching depth was less than 10%.

Abstract:Panax notoginseng is mainly grown in Yunnan Province. The planting area of Panax notoginseng has reached 672 km2 until December 2017. The row spacing and plant spacing of the seedlings of Panax notoginseng are only 50mm. In order to achieve high-density precision seeding of Panax notoginseng, an air-suction ultra-narrow-row device was designed for precise seed metering. Based on mechanical-pneumatic seed filling technology, the seed metering wheel had water drop-shaped holes on both sides. The seed metering device was compact. Compared with the air-suction cylinder seed metering device, the air chamber was smaller, which had lower requirements for air volume and wind pressure stability. The Wenshan Panax notoginseng seeds were chosen for seeding object. The simulation test of mechanical filling performance was based on the discrete element method, and the machining angle of water drop-shaped hole was taken as the single experimental factor. And the optimum of processing angle was obtained as 50°. Based on the three-factor quadratic orthogonal rotating combination test method, the influences of rotation speed of seed metering wheel, negative pressure of sucking hole and height of seed layer on seeding performance were explored. The experimental results showed that the affecting order of the qualified index was negative pressure of sucking hole, rotation speed of seed metering wheel and height of seed layer. Based on the results of examination, it was found that the fitting of the equations was good, the best parameter combination was pricking height of seed layer of 50mm, rotation speed of seed metering wheel of 34~48r/min and negative pressure of sucking hole of 560~660Pa, and under the optimal condition, the qualified index was greater than 93.0%, the missing index was less than 3.5%, the multiple index was less than 3.5% and variation coefficient of each row displacement consistency was less than 3.0%. The air-suction ultra-narrow-row device for precise seed metering met the standard and requirements by comparing the results with the national standard and Panax notoginseng planting requirements. The approach of research was suitable for the exploitation of Panax notoginseng seed-metering device.

Abstract:The longitudinal axial flow corn kernel harvester threshing separation device has high grain breakage rate during the threshing process, low removal rate, large loss of grain entrainment, and problem of clogging the concave plate by corn leaf. Aiming at the above problems, based on the collision contact theory, a degranulation separation device with low-damage round head nail teeth and segmented combined round tube threshing concave plate was designed. Combined with the physical properties of corn kernels, the relative critical velocity of the mechanical stress damage of the corn, the structural parameters of the optimal threshing element and the optimal gravure combination were determined. Based on the test factors of grain breakage rate and free removal rate, a comparison test was carried out with a conventional threshing rod and grid concave plate. It was determined through experiments that the optimal threshing element was a round head nail (equal height) and the optimal ball head radius was 12.5mm. The best gravure combination form was the right pipe and straight pipe (front sparse and rear dense). Under the optimal combination of parameters, the grain breakage rate of the threshing device was decreased from 13.73% to 8.64%;the unremoved rate was decreased from 0.6% to 0.2%. The device offered an effective solution for the problem of conventional grid gravure blocked by corn stalks, which met the design requirements and provided theoretical guidance for the design of corn threshing separation.

Abstract:In order to improve cleaning performance of air-and-screen cleaning device in maize harvester, the mechanism of throwing impurity, which was installed in the upper space of cleaning screen to make maize mixture disperse in the horizontal direction and layer in the vertical direction, was invented to meet requirements of the increasing feeding quantity. The CFD-DEM coupling method was used to simulate the delamination of maize mixture with the help of mechanism of throwing impurity in the vertical direction. The experimental factors were the numbers of raking finger in circumferential direction, the rotation radii of raking finger, the spacing between fingers axially and the angular velocity of roll, and the performance indexes were the horizontal displacement of impurity threw and the overlapping displacement of maize mixture in the horizontal direction. The quadratic orthogonal rotational-combinational simulation test was designed. The test data were analyzed by the response surface method, and the regression mathematical models were multi-objectively optimized by using Design-Expert. The results showed that the numbers of raking finger in the circumferential direction had the most significant effect on the horizontal displacement of impurity threw, followed by the angular velocity of roll, then the spacing between fingers axially, finally the rotation radii of raking finger and the numbers of raking finger in the circumferential direction had the most significant effect on the overlapping displacement of maize mixture in the horizontal direction, followed by the spacing between fingers axially, then the angular velocity of roll, finally the rotation radii of raking finger. The optimized parameters of the mechanism of throwing impurity were the numbers of raking finger in the circumferential direction, which was 8, the rotation radii of raking finger of 80.18mm, the spacing between fingers axially of 12.44mm and the angular velocity of roll of 15.41rad/s. Under the condition of inlet velocities of 12.8m/s and direction angle of the inlet of 25°， when the feed quantity of maize mixture at the entrance of cleaning device was 5~7kg/s,the cleaning rate of maize with mechanism of throwing impurity in cleaning device was 97.20%~98.74% and the loss rate of maize was 1.65%~1.82%, which can meet the requirements of technical specification for quality evaluation of screening under the condition of large feed quantity.

Abstract:As a kind of recyclable material, the residual film can be recycled and the pollution can be reduced only by separating the residual film from the impurity. However, the residual film, cotton core, cotton rod and other impurities after mechanical recovery are entangled seriously. So it is difficult to separate them, even to make use of resources. Direct incineration or centralized stacking of recovered residual film results in great waste of resources and serious secondary pollution. In order to solve the problem of high impurity content in waste film recovery, a spiral impurity cleaning device was put forward according to the working principle of the profile mode residual film collecting straw crushing combined machine. The structure and working principle of the spiral impurity cleaning device were introduced. The key parts of the device were analyzed and the parameters were designed. The three-dimensional discrete element model of cotton rod, soil and spiral impurity cleaning device was established by using EDEM software. The cleaning and conveying process of cotton rod and soil mixed particles was simulated. Taking the structure parameter pitch, the diameter of helical blade and outlet clearance of the spiral impurity cleaning device as test variables, orthogonal simulation experiments were carried out with mean particle velocity, average longitudinal particle velocity, mass flow rate and total helical axis torque as dependent variables. The influence of three test factors on each index was analyzed, and the order of primary and secondary factors was analyzed. The test results showed that the optimum parameter combination of the spiral impurity cleaning device was as follows: screw pitch was 200mm, screw blade diameter was 200mm, and outlet diameter was 220mm. Under the combination of these parameters, the device was made and assembled with the profile mode residual film recovery straw pulverizing machine. A performance test was carried out in the cotton field. The results showed that the cleaning effect of cotton rod and soil by the equipment was in accordance with the design requirements, and residual film and impurity separation rate was 89.51%.

Abstract:In order to reduce the cutting force and energy of millet stem, the reciprocating cutting test bench was developed to carry out the single factor cutting tests in different harvesting dates, stem region, combination of cutter, cutting inclination angle, blade oblique angle, average cutting speed and stem feeding speed. The response tests were carried out for three factors: average cutting speed, cutting inclination angle and blade oblique angle based on the single factor tests. The results of single factor tests showed that the cutting stress and unit area cutting energy were decreased with the increase of moisture content during harvest period. The cutting stress and unit area cutting energy were decreased with the increase of stem height, and the cutting stress and unit area cutting energy of internodes were lower than those of nodes. The cutting stress and unit area cutting energy of double-support cutting form were lower than those of single-support cutting form. When the cutting inclination angle was 0°~20°, the cutting stress and unit area cutting energy was firstly decreased and then increased with the increase of cutting inclination angle. When the blade oblique angle was 0°~48°, the cutting stress was decreased with the increase of blade oblique angle, but the unit area cutting energy was decreased firstly and then increased. When the average cutting speed was 0.5~1.5m/s, the cutting stress and unit area cutting energy were decreased firstly and then changed steadily with the increase of average cutting speed. The stem feeding speed had no significant effect on the cutting mechanical properties of the millet stem. The results of the response test showed that the order of three factors affecting the cutting stress and unit area cutting energy were as follows: average cutting speed, blade oblique angle and cutting inclination angle. The optimal cutting parameters were the average cutting speed of 1.19m/s, the cutting inclination angle of 7.2°and the blade oblique angle of 36.4°. Under the optimal parameters combination, the cutting stress and unit area cutting energy were 2.88MPa and 22.38mJ/mm2, respectively, and the relative error between verification test value and predicted value was less than 3.5%. The comparative test showed that the cutting stress and unit area cutting energy were reduced by 6.6% and 3.9%, respectively, when the blade oblique angle was 36.4° compared with that was 30° (standard typeⅡmoving blade).

Abstract:Aiming to effectively overcome the difficulty in plant protection robot operation with rollover and insufficient steering space when driving in furrows located field at the south of Anhui Province. Taking stability and steering sensitivity of the wheeled tobacco plant protection mobile platform into consideration, by analyzing and adjusting the transmission system and steering system of the mobile platform, a wheeled mobile platform for driving and operating in tobacco fields was designed. The simulation software RecurDyn/Track was used to build the dynamics and kinematics models, and the mobile platform was optimally upgraded and designed in terms of mobility and steering performance. The robot was tested in the field with high furrow to verify the simulation results. The results showed that these simulated models can turn around at the radius of 0.8m;the deviation was less than 3° when it was under straightwalking condition. And the optimum operating speed reached 1.0m/s through simulation analysis by comparing the motion stability at different moving speeds. All these numbers proved that the modelling robots were high in steering sensitivity and stability. Through the field experiment, the steering sensitivity of these modelling robots can meet the needs of tobacco fields in the south of Anhui Province. Furthermore, the inertial navigation device was used to test the deviation of the robots’ walking angle and the walking stability between the ridges. The largest tilting angle was 14.38° when the mobile plant protection machine operation speed was 1.0m/s. The research developed the design of mobile platforms in managing the high-ridge farmlands both in theory and technology. 

Abstract:Study on the three-dimensional (3D) canopy reconstruction of fruit trees plays a fundamental role in the calculation of canopy illumination distribution and the realization of automatic pruning. According to the characteristics of the leafy tree point cloud, an apple tree leaf points clustering method based on dynamic-K-threshold and a growth parameters extraction method were proposed. Firstly, terrestrial laser scanner Trimble TX8 was chosen to obtain dense point cloud of apple tree canopy from different viewpoints, and then multistation point cloud registration, outlier removal and point cloud simplification were accomplished, so as to reduce the influence of discrete points on calculation results of spatial characteristic parameters. Secondly, intercepting one branch randomly, synthesizing LCCP algorithm and improved K-means algorithm to construct the leaf points clustering method based on dynamic-K-threshold. Thirdly, as the input data, the leaf point cloud was used to construct the covariance matrix based on the PCA to calculate the fitting plane normal vector. Extracting boundary points, the parameters of width and length were obtained by calculating the position relation between boundaries and centroid. The results showed that compared with traditional clustering methods, the proposed dynamic-K-threshold method can accurately segment single leaf points without branch point losses, which ensured the integrity and thoroughness of the clustering results. The extracted parameters based on real 3D spatial information can guarantee the accuracy to a certain extent, which provided basic technical support for evaluation of illumination distribution calculation and automatic pruning.

Abstract:In order to support phenotypic parameter measurement and digital plant related research，the obtained maize point cloud data collected by 3D light detection and ranging (LiDAR) were analyzed and processed. The filtering algorithm of maize point cloud data was carried out, and a two times filtering algorithm based on statistical analysis was proposed. The vegetative stages of the 12th leaf, Jingnongke 728 and Nongda 84 maize were used as research objects, and VLP-16 was used to collect field maize point cloud data. Firstly, the point cloud data was subjected to pass filtering processing to remove extraneous points. The number of point clouds was reduced from 12000 to 1700. Secondly, the point cloud data was subjected to the first filtered process, and the precision and recall threshold were set. The average number of point clouds was reduced from 1700 to 1400, and 300 outliers were removed. Then, the point cloud was subjected to the second filtered process. The optimal combination and marginal combinations of precision and recall were determined. The optimal combination was (110,0.9) and (6,1.2). The marginal combinations were (100,1.0), (6,1.2) and (110,0.8), (5,0.9), a total of three combinations of parameters. The average number of point clouds was reduced from 1400 to 1300, and 100 outliers were removed. Finally, the three sets of verification set data were tested. The results showed that the optimal combination performance was optimal, which can be used to Jingnongke 728 and Nongda 84.

Abstract:With the development of intelligence and automation technology, people pay more attention to use it to monitor pig welfare and health in modern pig industry. Since the behaviors of group pigs present their healthy status, it is necessary to detect and monitor behaviors of group pigs. At present, machine vision technology with advantages of low price, easy installation, noninvasion and mature algorithm has been preferentially utilized to monitor pigs’ behaviors, such as drinking, eating, farrowing behavior of sow, and detect some of pigs’ physiological indices, such as lean yield rate. Feeding pigs at group level was used the most in intensive pig farms. Owing to normally happened huddled pigs showing in grouppig images, it was challenging to utilize traditional machine vision technique to monitor the behaviors of group pigs through separating adhesive pig areas. Thus a new segmentation method was introduced based on deep convolution neural network to separate adhesive pig areas in grouppig images. A PigNet network was built to solute the problem of separating adhesive pig areas in grouppig images. Main part of the PigNet network was established on the structure of the Mask R-CNN network. The Mask R-CNN network was a deep convolution neural network, which had a backbone network with a branch of FCN from classification layer and regression layer to mask the region of interest. The PigNet network used 44 convolutional layers of backbone network of Mask R-CNN network as its main network. After the main network, the output feature image was fed to the next four convolutional layers with different convolution kernels, which was the resting part of the main network and produced binary mask for each pig area. As well, the output feature image was fed into two branches, one was the region proposal networks (RPN), the other was region of interest align (ROIAlign) processing. The first branch outputted the regions of interest, and then the second one aligned each pig area and produced class of the whole pig area and the background area and bounding boxes of each pig regions. A binary cross entropy loss function was utilized to calculate the loss of each mask to correct the class layer and the location of ROIs. Here, the ROIAlign was used to align the candidate region and convolution characteristics through the bilinear difference, and which would not lose information by quantization, making the segmentation more accurate, and FCN of the mask branch used average binary cross entropy as the loss function to process each mask, which avoided the competition among pig masks. After all, the ROI was labeled with different colors. Totally 2000 images captured from previous five days of a 28day experiments were taken as the training set, and 500 images from the next 6th to 7th day were validation set. The results showed that the accuracy of the PigNet on training set was 86.15% and on validation set was 85.40%. The accuracies on each data set were very close, which showed that the model had effective generalization performance and high precision. The cooperation between the PigNet, Mask R-CNN (ResNet101-FPN) and its improvement showed the PigNet surpassed the other two algorithms in accuracy. Meanwhile, the PigNet run faster than the Mask R-CNN. However, the times of three algorithms spent on 500 samples of the validation set were similar. The algorithm can be used to separate individual pig from grouppig images with different behaviors and severe adhesion situation. The PigNet network model adopted the GPU operation mode, and used the three branches of class, regression box and mask to compute parallel processing time, which made the processing time of single image quick, only 2.12s. To a certain degree, the PigNet could reduce convolution parameters and simplify the network structure. The research provided a new segmentation method for adhesive grouppig images, which would increase the possibility of grouppig tracing and monitoring.

Abstract:Grassland degradation is an ecological problem facing the world. Investigating the species composition and species distribution of grassland is extremely important for judging the degradation process of grassland. At present, satellite remote sensing technology is difficult to meet the requirements of grassland species level classification due to the limitation of spatial resolution. Unmanned aerial vehicle (UAV) hyperspectral remote sensing technology provides images of centimeter level spatial resolution and nanoscale spectral resolution required for grassland species classification. Based on the UAV hyperspectral imaging remote sensing system, the hyperspectral image data of low and mixed growth desert grassland degradation indicator species were collected in the 400~1000nm spectral range. Flight experiments were carried out at the flowering, fruiting and yellow blight periods of the degraded indicator species. The flying height was 30m and the ground resolution of the hyperspectral image was about 2.3cm.Based on the combination of feature bands extraction and deep learning convolutional neural network (CNN), a method for classification of desert grassland species was proposed. The recommended phenological phase of species classification of desert grassland in central Inner Mongolia, China, was given in combination with plant phenology. The overall classification accuracy and Kappa coefficient reached 94% and 0.91, respectively. The results showed that the UAV hyperspectral imaging remote sensing technology and deep CNN can better classify the indicator species of desert grassland degradation. Compared with the support vector machine based on radial basis kernel function and the deep CNN based on principal component analysis, the deep CNN classification based on feature bands selection had the best effect and the highest classification accuracy. The method of CNN and the low-altitude remote sensing of UAV equipped with hyperspectral imager provided a new way to classify grassland species. The research result provided characteristic parameters for the judgment of grassland degradation succession process, and quantitative indicators for grassland ecological restoration management.

Abstract:Pine wilt disease (PWD) caused by the pine wood nematode, Bursaphelenchus xylophilus, is considered as the most destructive forestinvasive alien species and may cause serious economic losses. A ridge regression model was proposed based on the hyperspectral characteristics to estimate the degrees of pine wilt disease for Pinus massoniana in Yongsheng forest of Chongqing, Southwest China. The spectral reflectance and quantitated pet levels for Pinus massoniana were measured from June to August 2017. And then the ridge trace analysis was operated on 14 spectral characteristics, which covered maximum and sum of reflectance ranging in green region (490~560nm), yellow region (560~590nm), red region (620~680nm), red edge (680~780nm), near-infrared region (780~1100nm), as well as the reflectance height of green peak (500~670nm) and absorption depth of red valley (560~760nm). Furthermore, the hyperspectral characteristic parameters with less collinearity were selected to construct the estimation model of PWD with ridge regression. The results demonstrated that ridge trace curves for the maximum of reflectance in red edge, nearinfrared region, the sum of reflectance in the red edge, nearinfrared region, as well as absorption depth of red valley were stable, which were not close to zero. Therefore, those five spectral characteristics could be considered in ridge regression modeling;when the ridge trace parameter k was 0.2, the ridge traces of the above five hyperspectral characteristic parameters became stable, and then the ridge regression coefficients were calculated. Finally, a regression estimation model of PWD was built with determination coefficient R2 of 0.8686, rootmeansquare error (RMSE) of 0.2735, and average estimation accuracy of 87.15%. The research provided both scientific support and application reference for monitoring forest pet disease with remote sensing technology.

Abstract:For the low resolution of thermal infrared image, the crop canopy area can not be accurately extracted, and accurate canopy temperature can not be obtained. Maize in the jointing stage was taken as research object, and the thermal infrared image and orthophoto were obtained by using the UAV equipped with thermal infrared imager and the Dajiang Elf Pro UAV. Based on highresolution orthophotos, the improved Canny edge detection operator, support vector machine (SVM) and wavelet transform were used to extract the maize canopy region, and the classification results were binarized in thermal infrared imaging. The maize canopy temperature was extracted by using the mask generated by the binarization result. The extracted vector surface analysis extraction effect was applied and the accuracy of the three extraction algorithms was evaluated. The experimental results showed that the effects of the three methods from strong to weak were as follows: improved Canny edge detection operator, SVM and wavelet transform;the extraction accuracy was 87.3%, 74.5% and 68.2%, respectively. At the same time, the error analysis of the maize canopy temperature measured by the handheld thermometer and the extracted canopy temperature was performed. The experimental results showed that the correlation between the canopy temperature extracted by the three algorithms and the measured temperature of the ground from strong to weak was as follows: 0.9295, 0.8957 and 0.8760. The improved Canny edge detection operator can better extract the maize canopy area and obtain more accurate maize canopy temperature, so as to more effectively monitor the physiological status of maize, predict drought, and formulate reasonable irrigation and fertilization measures to increase maize yield.

Abstract:The information of crop lodging is very important for agricultural hazard assessment and agricultural insurance claims. Remote sensing is a fast and efficient technology to gain the information of crop lodging, but satellite remote sensing cannot provide available data. Recently, unmanned aerial vehicle (UAV) remote sensing system has grown rapidly, and UAV remote sensing system can get available data neatly and fleetly. There was no survey on winter wheat lodging by using multitemporal UAV remote sensing data. Therefore, a survey method of winter wheat lodging was proposed by using images derived from the UAV remote sensing experiments, which were carried out in the winter wheat test field of Institute of WaterSaving Agriculture in Arid Areas of China (IWSA), Northwest A&F University on May 4th and 16th of 2017. Images were handled with the second low pass filter firstly to enhance the image space domain. Then the scatter diagram of lodging and unlodging wheat was gained in different feature combination coordinate systems. The single features of wheat lodging information extraction based on the welldefined boundary of the scatter diagram were selected. Feature parameters F1 and F2 were gained by fitting boundary points of May 4th and 16th. Using the similarities of F1 and F2 can obtain F3 to extract winter wheat lodging information of two periods. Using F1, F2 and F3 combined with K-means to extract the lodging information of winter wheat. It was turned out that the overall accuracy was over 86.44%, the Kappa coefficient was over 0.73, and the lodging extracting accuracy was over 81.07%, so F3 can be the feature parameter to extract the lodging information of two periods. To research the accuracy and versatility of this method, two verification areas were selected and the method of this paper, support vector machine (SVM), neural network and maximum likelihood method were respectively used to extract the lodging information of winter wheat. The results showed that the overall accuracy, Kappa coefficient and lodging extracting accuracy of the method were over 86.29%, 0.71 and 80.60%, and the overall accuracy, Kappa coefficient and lodging extracting accuracy of the other common methods were 69.68%～87.44%, 0.49～0.72 and 65.33%～79.76%, respectively. The results indicated that the overall accuracy, Kappa coefficient and lodging extracting accuracy of this method were all tower over other methods. Therefore, the proposed method was accurate and versatile to extract the lodging information of winter wheat in the watery stage.

Abstract:In view of the need to achieve high-precision positioning and navigation in forest resources investigation and monitoring, taking the experimental area with cork ridge as main tree species in the Jiufeng National Forest Park, and the Sanding T-23 multi-frequency Samsung receiver and u-blox NEO-M8T multi-receiving modules to carry out a four-hour positioning observation on the observation points in the forest, and the forest BDS/GPS combined positioning algorithm was established by using BDS and GPS observation data through unifying time and space between systems as well as reasonable observation weights. Afterwards, the algorithm was put into the RTKLIB software to realize three-dimensional coordinate calculation of forest observation points (WGS-84 coordinate system), and finally the results were compared and analyzed with single GPS positioning results. The experimental results showed that the visible digits of forest BDS/GPS combined positioning satellites was 15~23, which was much higher than the visible digits of single GPS positioning satellites (the number was 11). The BDS/GPS combined positioning PDOP value was between 0.5 and 1.8, which was lower than that of the single GPS positioning PDOP value, but the changing trend was relatively similar. The SNR values of BDS/GPS combined positioning and GPS positioning satellite were both 10~50dB. However, due to the more visible digits of BDS/GPS combined positioning satellites, the satellite signal was stronger and the SNR value was more stable. The theoretical accuracy of the BDS/GPS combined positioning results in the X, Y and Zdirections respectively were 2.603m, 3.302m and 3.125m, and the theoretical accuracy of the single GPS positioning results in the X, Y andZ directions were 2.382m, 4.669m and 4.344m. The actual accuracy of BDS/GPS combined positioning results in X, Y and Z directions were 3.112m, 3.542m and 4.073m, and in terms of the single GPS positioning result, it turned out to be 4.946m, 5.254m and 7.274m.

Abstract:Due to the rapid development of urbanization and industrialization, the consequent increasing conflict between limited water resources and increased water demands gradually led to unsustainability of water resources utilization in an irrigation district. Therefore, it is crucial to optimize the water allocation to alleviate water shortage and promote the sustainable development of irrigation district. Taking Zhanghe Irrigation District in Hubei Province as an example, an intervalparameter twostage stochastic fuzzy credibility constrained programming was developed for optimal water allocation. In the model, the maximal system benefit was regarded as the objective function. To reflect the multiple uncertainties, fuzzy variables, discrete intervals and probability distributions were introduced into the model framework. To address the fuzzy risk problems associated with the violation constraints, fuzzy credibility constrained programming was integrated into the intervalparameter twostage stochastic programming model. Meanwhile, several credibility significance levels were given to examine the system failure risk. Optimal allocation schemes were obtained in the combination of different credibility levels (λ), inflow levels and fuzzy membership levels (α). The results indicated that the water inflow was positively related to the water resources allocation and agricultural irrigation areas;water and irrigation area allocation to all divisions were increased with the decrease of credibility level, which resulted in system benefit’s expansion coupled with high violation risk. When λ was 10, the system benefit range was [0.741, 1.147] billion CNY, and when λ was set as 0.8, the system benefit reached [1.026, 1.325] billion CNY;with the increase of the α level, the system fuzzy feature was weakened, consequently the upper limit of the system benefit was gradually decreased and the lower limit of the system benefit was increased conversely;and the proposed model preferred to avoid high violation risk rather than purse high economic benefit impractically to some extent. The corresponding optimal results were helpful for managers to coordinate the conflict-laden water use issues, formulate reasonable allocation schemes, and achieve efficient utilization of water resources. Compared with the other optimal allocation in Zhanghe Irrigation District, the research had advantages as following: multiple uncertainties were considered and represented by proper mathematical methods;the tradeoff of system benefit and violation risk was reflected;multiple allocation schemes were provided under different scenarios;several engineering and nonengineering measures were suggested for sustainable development of Zhanghe Irrigation District;the analysis method and the model framework can also be applied to other similar regions.

Abstract:The problem of selecting the best pattern of layout and pipe diameter of each pipe in the micro-irrigation pipe network system has long been given considerable attention by engineers and obtained numerous research results. Micro-irrigation pipe network system is composed of rotational irrigation network (manifold and lateral) and continuous irrigation network (main and submain pipe). Previous studies did not treat micro-irrigation pipe network system as an integral and can not realize the simultaneous optimization of layout and pipe diameter combination. In addition, research results can not be applied to the optimization of pumping microirrigation pipe network system for large irrigation area. The optimization method of pumping micro-irrigation pipe network system was proposed. The mathematical models of rotational irrigation network and continuous irrigation network were established. The best control area, layout and pipe diameter of rotational and continuous irrigation network can be obtained simultaneously by solving the mathematical model with dual coding genetic algorithm. Commercial pipe diameters can be obtained through the optimization without adjustment. Examples showed that the algorithm was of good convergence and high precision on optimization problem of pumping microirrigation pipe network system. Compared with the traditional design scheme, the annual total cost per unit irrigated area of optimized design scheme for rotational irrigation network was reduced by 14.85%~35.59%, and the annual total cost per unit irrigated area of optimized design scheme for continuous irrigation network was reduced by 4.12%~12.99%. The simultaneous optimization method of layout and pipe diameter can be applied to the optimal design of pumping microirrigation pipe network system on uniformly sloping fields which with sufficient water source. The research result had important theoretical value and practical significance in the optimization of pumping micro-irrigation pipe network system for large irrigation area.

Abstract:In order to explore the effect of rice water consumption characteristics on WUE in cold black soil region, the experiment was carried out by lysimeter at the rice irrigation experiment station of Heilongjiang Province in 2017. The U7（76）experiment was conducted to analyze the variation regular of water consumption of rice stage water consumption, during daytime, nighttime and hourly at different growth stages, the effects of water consumption at different growth stages on WUEand biomass WUE were clarified. The results showed that water consumption and water consumption percentage were the highest at the jointing-booting stage, which were 77.25mm and 23.09%, respectively. The daytime and nighttime water consumption of rice showed a trend of “low-high-low”, The daytime and nighttime water consumption reached the maximum at the headingflowering stage, which were 6.32mm/d and 0.76mm/d,respectively. The water consumption characteristics of rice in the daytime showed an inverted “V” curve at the early and midtillering stage, the water consumption peak was at 12:00—13:00. It showed an “M” curve from the late tillering stage to the milky stage, the water consumption peak was at 11:00—12:00 and 13:00—14:00, respectively. The time of the maximum water consumption was at 10:00—11:00 during the milky stage. The direct effect of stage water consumption on WUEand the total contribution to R2 were consistent, and the order from large to small was ET5, ET2, ET4, ET3, ET6 and ET1. The water consumption at the late tillering and milky stage had a direct negative impact on WUE, the order of the determinant coefficient of water consumption in each stage on WUEwas ET5, ET4×ET5, ET2×ET5, ET2 and ET4. There were significant positive correlations between SWUE5 and rice yield and WUE, the effect order of water consumption on SWUE5 from the early tillering to heading-flowering stage was ET5, ET4, ET3, ET1 and ET2. The study would be helpful in understanding water consumption and water use efficiency of rice and formulating water-saving plan in black soil region.

Abstract:In order to explore the soil water recovery under deep ground cover in the loess hilly region, a simulated soil column with depth of 1000cm and diameter of 80cm was constructed in the hilly hills of northern Shaanxi, and there were six treatments of surface: the film mulching was provided with 16 small holes with an asymmetric diameter of about 2mm for rainwater to enter and regularly updated every year;the stone mulching was uniform graveled with diameter from 2cm to 5cm, covering a thickness of 10cm;the branch mulching was cut jujube branches, the length was about 10cm, evenly covered after drying, the thickness was 10cm;bare land without any covered;planting jujube with a diameter of 1cm and height of 50cm, without any other covering measures, regularly removed weeds;planting locust with a diameter of 1cm and a height of 50cm, without any other covering measures, regularly removed weeds. Soil moisture content of sloping farmland was taken as reference. Analysis of the positioning monitoring data for 2014—2017 showed that at the end of the trial period, taking the average water content of sloping farmland as the recovery target, the film mulching, stone mulching, branch mulching and bare soil moisture recovery depth was 1000cm, 1000cm, 700cm and 480cm;taking the actual soil water content of sloping farmland as the recovery target, the film mulching and stone mulching soil moisture recovery depth was 1000cm, the branch mulching recovery depth was 740cm, and the bare land recovery depth was 440cm. From the degree of recovery, the results were consistent. The water storage capacities of film mulching, stone mulching, branch mulching, bare land, jujube tree and locust were increased by 1211.4mm, 853.4mm, 662.5mm, 523.2mm, 17.8mm and -235.7mm, respectively. The precipitation storage efficiency were 63.4%, 42.4%, 29.4%, 23.0%, -8.5% and -20.3%, respectively. The water consumption area of four years old jujube was ranged from 0cm to 300cm, its annual average evapotranspiration was 586.4mm, locust consumed water up to 1000cm, and its annual average evapotranspiration was 666.5mm, which was 1.1 times of jujube. The research result had positive significance for the largearea dry soil restoration in the loess area and the rational selection of artificially planted plants.

Abstract:Totally 1165 surface soil samples for heavy metal analysis were collected in oasis area of Yutian County, Xinjiang. Spatial distribution and influence factors of heavy metal elements in soils in the study area were analyzed by means of multivariate statistical analysis, geostatistics, spatial autocorrelation, spatial analysis and GIS technology. Results showed that among 1165 soil samples, three of which had As contents greater than the risk screening values. Average contents of heavy metal elements in nonagricultural lands were lower than that of soil background values in Xinjiang. Average values of Cd, Hg and Cr contents in agricultural land were greater than that of soil background values in Xinjiang. The theoretical models for variation function of Cd and PB were exponential model, while the theoretical models for variation function of Hg, As, Cr, Cu, Ni and Zn were spherical model. Nugget value of Cd was less than 25%, indicated a relatively strong spatial correlation. Nugget value of other elements ranged between 25% and 50%, indicated significant spatial correlations. As for soil heavy metals, the Moran’s I indexes of spatial autocorrelation were greater than 0. There was a positive spatial correlation distribution of soil heavy metal elements in the county scale. And the spatial distribution of soil heavy metal contents in oasis area of Yutian County showed a general decreasing trend from the center of the study area to surrounding areas. Distribution of soil heavy metal contents in the Yutian County varied in different parent materials, soil types and land use patterns. Hg, As, Pb, Cr, Cu, Ni and Zn in soils derived from the same source. However, the contents were affected by soil texture as well.

Abstract:Dynamic quantification of field ephemeral gully development and morphology on natural hillslope has great significance on ephemeral gully erosion control and ephemeral gully erosion modelling. Due to the difficulty of dynamically monitoring field ephemeral gully catchments and limitation of measurement method, quantification of ephemeral gully morphology and its dynamic evolvement process is still lacking. Thus, based on the long-term field ephemeral gully development investigation data, three-dimensional laser scanning and photogrammetry techniques were used to quantify the ephemeral gully morphology of three ephemeral gully catchments with different upslope drainage areas (1012m2, 995m2 and 424m2). The dynamic evolution processes of ephemeral gully were revealed, and the relationship between drop-sills distance of headcuts and slope gradient was also analyzed. The result showed that during the monitoring period from 2003 to 2015, when upslope drainage area was increased by 34.8% and 159.6%, ephemeral gully length was increased by 39.6% and 138.8%, average ephemeral gully width was increased by 19.7% and 75.3%, and average ephemeral gully depth was increased by 32.4% and 71.4%, respectively. Dynamic monitoring illustrated that ephemeral gully length was increased by 26.4%，12.1%，29.4% from 2003 to 2015 and the increasing rate was 0.82m/a，0.55m/a，0.5m/a;the crosssection areas of ephemeral gully in 2015 was increased by 22.5%，65.1%，45.9% compared with those in 2013, and the increasing rate was 5.0cm2/a，15.8cm2/a，4.1cm2/a. Tillage in spring brought the lateral topsoil into the ephemeral gully channel which induced 2cm decrement of soil layer around the channel. With the increase of slope length, ephemeral gully width and depth were increased first and then decreased, with maximum value in the location of about 20m to the slope bottom. Totally 70% of drop-sills distances of headcuts in ephemeral gully channel were distributed in 10~25cm, while slope gradients were distributed in the range of 15°~40°. A negative exponent relationship can be found between dropsills distance and slope gradient. The research results enhanced the understanding on ephemeral gully erosion processes, which could provide scientific bases for ephemeral gully erosion control.

Abstract:Through chemical equilibrium thermodynamics analysis of CO2 gas-liquid absorption process, the number of independent reactions in the absorption reaction system was calculated and a fourindependent reaction hypothesis was presented. According to the calculation of the independent reaction equilibrium constants, ionization of H2CO3 into H+ and HCO-3 was postulated. Although the equilibrium constant was 6.0189×10-7, the concentration of H+ ions was still very low due to the large presence of CO2-3 ions in the solution, such that the ionization degree of H2CO3 can not be ignored. Moreover, it was proposed that the reaction mechanism of CO2 gas-liquid absorption was a serialparallel complex. The absorption rate of CO2 was believed to be determined by its parallel reactions with H2O and OH-. Meanwhile, the critical roles of CO2-3 ions were analyzed in great detail. Firstly, the interaction between H+ and CO2-3 directly promoted the absorption of CO2;secondly, the concentration of OH- ions in solution was increased as the decrease of concentration of H+ ions. The latter indirectly accelerated the reaction rate between CO2 and OH- ions. A dualdrive reactor was used to study the gasliquid mass transfer process in H2O-CO2 system and the main conclusions were as following: when the gas phase stirring rate reached above 140r/min, the mass transfer resistance of the gas film can be negligible;based on the linear regression analysis, the relationship between the liquid mass transfer coefficient and the speed of liquid phase stirring paddle was verified and the regression correlation was obtained. By calculating the residual, the maximum value was 11.312%，and the correlation was considered to be robust.

Abstract:In order to effectively improve the bio-oil upgrading efficiency, the non-thermal plasma technology was introduced to conduct the online upgrading of bio-oil based on the HZSM-5 and Ti/HZSM-5 catalysis. The effects of different compound modes, including the plasma synergistic catalysis (PSC) and the plasma enhanced catalysis (PEC), on the refined bio-oil yields, physicochemical properties, compositions and catalyst stability were investigated in detail. The results showed that the production of refined bio-oil was gradually decreased with the introduction of Ti ions and plasma-discharge technology, in which the yield of refined bio-oil obtained from Ti/HZSM-5(PEC) catalysis was only 13.84%, but the distribution of hydrocarbons was obviously improved. In comparison, the total hydrocarbon content in the refined bio-oil obtained from Ti/HZSM-5(PSC) catalysis was slightly lower, but the product ratio with higher ratio of hydrogen to carbon was high as 68.89%, so its physicochemical properties were better and the high heating value was up to 36.52MJ/kg. In the PSC method, the impact of plasma on the surface of catalyst was stronger, which made the coking rate of catalyst relatively low, so the coking content of Ti/HZSM-5 employed in the PSC method was the lowest (integral area of 5.24%) and the catalytic stability was the highest. In general, the PSC method was superior to the PEC method based on the catalytic action of Ti/HZSM-5.

Abstract:In the traditional corn stover cellulose separation process, it is generally treated with strong acid such as sulfuric acid, which has strong acid corrosion and large alkali consumption. Based on this, the treatment of phosphoric acid pretreatment combined with alkaline hydrogen peroxide was studied, and the changes of cellulose, hemicellulose and lignin contents in corn stover during the treatment were investigated. The optimum process was optimized by single factor experiments: phosphoric acid treatment temperature of 150℃, treatment time of 1.5h, phosphoric acid concentration of 1.67%, sodium hydroxide concentration of 1.0%, hydrogen peroxide concentration of 2.0%, treatment temperature of 50℃, treatment time of 3h, the yield of cellulose obtained from corn stalk under this condition was 89.02%, hemicellulose removal rate was 93.25%, lignin removal rate was 95.18%, the purity of the cellulose reached 90.19%. Meanwhile, a high secondary value product can be obtained in the filtrate obtained by the phosphoric acid treatment process, including xylose of 68.72%, arabicose of 65.14% and furfural of 30.25%. The characterization of the raw materials and the treated materials showed that the phosphoric acid treatment can effectively remove the hemicellulose and the alkaline hydrogen peroxide treatment can remove lignin components. The cellulose crystal form was not changed, but the crystallinity was increased significantly, and the thermal stability was increased. In addition to obtaining highpurity cellulose, the use of this preacid postbase treatment can also give high added value as a by-product of xylose and furfural. The research laid a theoretical foundation for the efficient utilization of corn stover cellulose.

Abstract:A multi-temperature vehicle incorporating phase change material (PCM) was designed to help multi-temperature joint distribution and widen temperature control range, which integrated on-board refrigeration system, the phase change cold storage tank (PCCST), heat-insulated compartment (divided into freezing and cooling unit), air guiding device, thermal insulation board and so on. The PCCST (using 360kg PCM, which had a melting temperature of -30.0℃ and a latent heat of 175.3kJ/kg) was set independently in front of the vehicle and charged by a refrigeration system by using cheap electricity at night when it was stationary. During transportation, the freezing unit derived and regulated the cold air from PCCST through the air supply system of the heatinsulated carriage, and the cooling unit imported and regulated the cold air through the air guiding duct on one side above the heat-insulated carriage. The results of simulation and experiment were compared and analyzed as follows when the space ratio of freezing unit to cooling unit in the heatinsulate carriage was 1∶1, and the temperature was set to be -15.0℃ and 3.0℃, respectively. It was showed that the temperature root mean squared error between simulation and test was between 0.7℃ and 1.1℃, and the overall deviation was reasonable, which could better reflect the distribution of temperature field in the multitemperature cold storage vehicle. In addition, the results showed that the multi-temperature cold storage vehicle could maintain the temperature of the products at -15.0℃ and 3.0℃ for more than 10h during the transportation. In fact, the average air temperature of the multitemperature carriage was distributed between -14.2~-12.9℃ and 3.4~4.2℃ whose fluctuation ranges were 1.3℃ and 0.8℃, respectively. The coefficient of absolute nonuniformity of temperature was less than 0.6 when the freezing unit was -15.0℃ and less than 1.2 when the cooling unit was 3.0℃. The above parametric study showed that the average temperature fluctuation value of novel multi-temperature cold storage vehicle was 73.7% and the coefficient of absolute nonuniformity was 50% lower than that of the traditional cold storage vehicle. The further simulation of changing the space ratio of freezing unit to cooling unit in the carriage also showed that the temperature field in the carriage was uniform and could meet the actual transportation needs.

Abstract:In order to solve the problem of nonuniformity of material drying caused by difference of heating plate and disturbance of air flow in vacuum pulse drying, a hardware circuit for controlling radiation intensity of heating plate based on zerocrossing trigger control was designed. The control circuit was designed as daisychaining connection mode to facilitate installation and expansion. Combining the theory of PID control with outlier detection method in data mining technology, an integral separation PID control strategy for temperature outlier optimization of heating plate was proposed. The control effect of the control system was validated by using the uniform moisture content of the patches as the test material and the uniformity of drying as the evaluation index. The experimental results show that the control system can effectively reduce the difference of radiation intensity between different heating plates. The average temperature control accuracy was ±0.8℃ and the initial transient time was 120s. The surface temperature of heating plate can recover quickly after disturbed by air flow disturbance. In terms of drying uniformity, the outlier optimization integral separation PID control was superior to the heating plate independent PID control and the heating plates whole PID control. It can reduce the influence of air disturbance on drying uniformity and improve the drying uniformity of the patches from 90% to more than 95%.

Abstract:With the continuous improvement of people’s living standards, consumer demand for apple has shifted from quantity to quality. However, for small-scale farmers, the detection equipment developed on the market based on spectrometers is expensive, resulting in difficulty in purchasing, and thus it is impossible to achieve high-quality fruit screening. Therefore, the object was to develop a lowcost, portable apple multiquality parameter integrated detection device. Firstly, diffuse spectral information of 240 Fuji apples was acquired based on the visible/near-infrared spectroscopy platform. After SG smoothing and multiple scattering correction algorithm pretreatment, the characteristic wavelength of soluble apple solid, titrable acid and pulp firmness was extracted by random frog algorithm. So the ten shared characteristic wavelengths of the three parameters, namely 420nm, 480nm, 550nm, 580nm, 640nm, 680nm, 705nm, 940nm, 980nm and 1044nm, were selected. On this basis, a detection method combining a characteristic narrow-band LED light source and a photodiode was proposed. Then, hardware systems such as diffuse reflection detection optical path, narrow-band LED ring light source, detection probe, control circuit and so on were designed. Secondly, the diffuse reflection characteristic voltage intensity of 144 apple samples was obtained by the detection device. Then the multivariate linear regression models of soluble solids content, titratable acid and firmness were respectively established by the obtained information. The correlation coefficients of the prediction set were 0.8129, 0.8073 and 0.7736, and the root mean square errors were 0.6036°Brix, 0.0636% and 1.7325N, respectively. Based on the QT development tool, the realtime control and analysis software of the device was developed in Python language, and the multiquality parameter prediction model of apple was implanted to realize the simultaneous detection and analysis. Finally, to test the precision and stability of the device, another 46 samples were selected and each sample was tested eight times. The predicted results of the device were acceptable, and the correlation coefficients of soluble solids, titratable acid and pulp hardness of apple were 0.8096, 0.7962 and 0.7589, and root mean square errors were 0.6973°Brix, 0.0703% and 1.8323N, respectively. The maximum variation coefficients of the resampling were 0.0106, 0.0116 and 0.0062, respectively. The results showed that the low-cost, portable nondestructive testing device based on multi-featured narrow-band LED light source can realize the simultaneous detection of multiple quality parameters of apples, which can meet the needs of farmers for field production and e-commerce sales of high-quality fruit screening.

Abstract:In order to detect the different degrees of mildew of peanut kernels in an efficient, convenient and reliable way, a qualitative analysis method of mildew peanut based on back propagation（BP）neural network algorithm and support vector machine based on Terahertz (THz) time-domain spectroscopy was studied. In order to eliminate the contingency brought by different peanut samples, two peanut varieties, Huayu 36 and Luhua 9, were randomly collected for mildew culture. According to the sensory characteristics of peanut and the existing research foundation, the peanut samples were divided into four categories: normal, mild mildew, moderate mildew and severe mildew. The spectrum of peanut kernel samples (band 0.3~3.6THz) was collected by THz total reflection. The Fourier transform method was used to perform frequency domain transformation on the time domain spectral signal and window processing. Then the optical constant absorbance and absorption coefficient of the obtained frequency domain signal were extracted, and the optical constant signal of the sample was obtained and the characteristic band was screened. On this basis, BP neural network qualitative analysis model and SVM qualitative analysis model were established respectively. Experiment results showed that the BP neural network model had a prediction set recognition rate of 88.57% for the Huayu 36 peanut mold model, and the prediction set recognition rate of the Luhua 9 peanut model was 91.40%;the Lib-SVM model for two varieties of peanut mold whether or not the two-class model, the three-class model of the three types of mildew peanuts had a prediction set recognition rate of 100%. It was shown that the application of Terahertz time-domain spectroscopy combined with BP neural network algorithm and SVM algorithm had a good effect on detecting mildewed peanut kernels.

Abstract:The lairage process can significantly affect the quality of meat. The yield of mutton is relatively large in China. So it is necessary to strengthen the exploration in this respect. The effects of different lairage times (0h, 3h, 6h, 12h, 18h and 24h) on stress level and mutton quality of Small Tail Han sheep after 5h transportation were compared. The suitable lairage time was established and it was meaningful in mutton production. The results showed that 12h lairage could increase the glycogen content to (7.74±0.98)mg/g, decrease the final pH value to 5.57±0.14, and improve the tenderness of mutton. The plasmacortisol and creatine kinase contents were slightly increased and then decreased with the extension of lairage time. The lowest data could be seen in the 12h lairage group, which were (39.98±5.04)ng/mL and (277.64±19.88)U/L, respectively, indicating that Small Tail Han sheep could be relieved from stress caused by transportation. In addition, with the extension of lairage time, the weight loss of Small Tail Han sheep was increased. The concentrations of hemoglobin and hematocrit were increased to (40.63±0.85)% and (14.01±0.23)g/dL, respectively after 24h lairage, indicating that new stress was caused because of the extension of lairage time. Therefore, combined with the above indicators, 12h lairage time could ensure the minimum weight loss of Small Tail Han sheep and make them relieve from stress, improving mutton quality. The research was of great significance to the formulation of standards for mutton slaughtering industry and the guidance of mutton production.

Abstract:Whole egg liquid is nutritious, and contains proteins, lipids, carbohydrates, vitamins and other components needed by human body. Based on the demand of low phosphorus’ diet in patients with kidney disease, layered double hydroxide (LDH) adsorption method was used to reduce the phosphorus content of whole egg liquid, aiming to develop a low phosphorus liquid egg product and provide a special diet for patients with kidney disease. The effects of initial phosphorus concentration, adsorption time and the amount of LDH on the quantity of adsorption and solubility at different adsorption temperatures were studied, and the kinetic models were also analyzed. Meanwhile, the effects of volume and desorption time on desorption characteristics of LDH and the reuse of LDH were investigated. The results showed that the quantity of adsorption of phosphorus was proportional to absorption time within 1~7h, and the values of the quantity of adsorption and solubility were increased with the increase of initial phosphorus concentration at all temperatures (20~45℃). When the LDH content was 10g/L, the adsorption degree was good at all temperatures. In the model analysis, Langmuir isothermal model and quasi-second-order kinetic model had high fitting degree, especially at 25℃ and 30℃. In the thermodynamic model, ΔG was negative and ΔH was positive, and the adsorption was spontaneous and endothermic. In the desorption experiment, the optimum condition was desorption for 5h, the ratio of desorption liquid to LDH was 1.00L/g, and the two times in cyclic utilization could maintain a better adsorption degree. After dephosphorization, the percentages of essential amino acids in total amino acids and in nonessential amino acids were more than 40% and 60%, respectively, which had little effect on protein nutrition. In conclusion, LDH was a suitable adsorptive material for removing phosphorus from whole egg liquid, and can be used for the development of special liquid egg products for patients with kidney disease.

Abstract:For the obstacle avoidance control of agricultural tractor-trailers, a controller based on nonlinear model predictive control was proposed. Since the obstacle avoidance control of the agricultural tractor-trailer should take the position state and the attitude state of the tractor and trailer into account, the kinematics model of the agricultural tractor-trailer was derived based on rigid body kinematics and non-holonomic constraints. And based on this kinematics model, the position state and the attitude state prediction model of the agricultural tractor-trailer was established. Thereafter, the optimization function was designed based on the improved forbidden zone penalty function, and the proposed obstacle avoidance controller design was completed. In the simulation results, by comparing with the obstacle avoidance controller that did not consider the position state and the attitude state of the trailer, it can be known that the proposed obstacle avoidance controller of agricultural tractortrailers can control the tractor and the trailer to avoid the obstacle simultaneously. And under the control of the proposed obstacle avoidance controller of agricultural tractor-trailers, the minimum distance between the trajectory of the end point of each axle and the center of the obstacle minus the sum of the obstacle radius and the safety margin was not less than 0m.

Abstract:Thermal equilibrium test of CNC machine tool spindle is a necessary step in thermal error modeling and compensating, and also an experimental method to obtain the thermal characteristics of spindle system, such as the thermal sensitive points, the data of temperature field and thermaldisplacement field and so on. A novel method was presented for fast identification of a machine tool spindle temperature rise, based on a modified adaptive fading unscented Kalman filter (AFUKF). Firstly, a fading factor was introduced into the normal UKF. This factor can be automatically updated by using the residual normalization, and it was also introduced into the gain matrix to reduce the influence of system model deviation on estimation accuracy and enhance the stability of the filter. Secondly, by using adaptive law, the process noise and measurement noise covariance matrix were dynamically adjusted to reduce the influence of external disturbance on temperature rise prediction, so that the better filtering performance can be obtained. A vertical machine tool was used to validate the effectiveness of the presented method. Taking any selected point, we could identify the temperature rise at the point in 28min. The root mean square error (RMSE) between the estimated and measured temperatures in the period of 400min was 0.1291℃, and the error between the estimated and measured steady-state temperature was 0.097℃. The simulation experiments showed that the method of fast identification of machine tool spindle temperature rise can predict the temperature rise of the selected point in a short time, and the prediction results were in good agreement with the results of thermal equilibrium test. The feasibility and validity of the method were verified, and it can greatly improve the efficiency of thermal equilibrium test.

Abstract:According to the structural characteristics of the planar 6-UPS parallel robot, the position and orientation of the mobile platform were described by choosing the spatial coordinates of three representative points as parameters. Combination of the constraint conditions during three representative points, nine quadratic polynomial equations with nine parameters were obtained. Finally, six quadratic polynomial equations, including six unknown parameters were obtained by eliminating three parameters of the nine equations. Aiming at the characteristics of the obtained quadratic polynomial equations, the traditional Newton-Raphson numerical iteration algorithm was improved and used to the numerical solution of general six-dimensional quadratic polynomial equations of parallel robots. The iterative algorithm was converged and an unique solution was obtained. The numerical example demonstrated that the time consumptions of the proposed algorithm was 0.14~0.23 ms and the traditional method of rotation matrix was 1.42~2.67 ms respectively under the same conditions. The proposed algorithm of representative points greatly reduced the computational time, improved the convergence speed and computational efficiency and laid a better foundation for the closed-loop realtime control with high-performance of the six DOFs planar parallel robot.

Abstract:The three-translation and one-rotation (3T1R) parallel manipulator with zero coupling (κ=0) and motion decoupling is not only simple in kinematics and dynamics analysis, but also easy in control. Therefore, its research and development has attracted much attention. Firstly, a novel 3T1R parallel mechanism was designed according to the topological design theory of parallel mechanism based on the position and orientation characteristic (POC) equations and principle of avoiding singularity by using redundant actuation limb. Secondly, the topological structure of POC was analyzed, including POC set, degree of freedom, motion decoupling and coupling degree analysis, which showed that the coupling degree was zero, which had partial motion decoupling. Then, according to the kinematics modeling principle based on the ordered single opened chain (SOC) method proposed by the author, the forward kinematic solution of the parallel mechanism was solved. Thirdly, based on the derived inverse kinematic solution, the workspace, rotational capacity and singularity conditions of the mechanism were analyzed. Meanwhile, the law of velocity and acceleration of the moving platform was given. The curves of velocity and acceleration were given by ADAMS and the numerical values were verified by Matlab based on the derived formulas. The research laid a theoretical foundation for the mechanical design of parallel manipulator, dynamic analysis and prototype development.

Abstract:According to the present problems that the forward displacement analysis of most platform Stewart parallel mechanisms with six links can not be described with whole analytical solutions, and a very few of them can be described with whole analytical solutions and also with these difficulties, including calculation and programming, four kinds of platform Stewart derivative configurations with six links were designed, and a semi-analytic algorithm which combined with numerical method and analytical method was established. By adding six virtual links, the four derivative configurations can be reconstructed into the same kind of 12-6 platform topological configuration. Compatibility equations of reconstructed configuration were derived, and aimed at four kinds of derivative configurations, the numerical solution of the length of the virtual links was derived. Based on the topological relations between feature points on the moving platform, the whole analytical solution of the forward displacement analysis of the reconstructed configuration was derived. Furthermore, the accuracy, efficiency and stability of the semi-analytic algorithm and the traditional numerical method were compared and analyzed respectively. Numerical examples showed that the accuracy and stability of the semianalytic algorithm was at least two times of that of the traditional numerical method, but the efficiency of the traditional numerical method was seven times of that of the semi-analytic algorithm. Meanwhile, three selection principles of configurations were obtained, which established theoretical foundation for the engineering application of six links parallel mechanism.

Abstract:The dynamic modeling and analysis of a new kind of bionic robot which had the characteristics of large capacity，fast walking and good lateral decoupling was carried out. Firstly, the layout of the leg mechanism was introduced, the kinematics analysis was carried out, the explicit linear velocity Jacobi was established, and the explicit expressions of each component’s velocity and terminal linear velocity were derived, which laid a foundation for dynamic modeling. Then, the explicit dynamic equation of leg mechanism was established by using Lagrange equation, and the inverse dynamics of leg mechanism was deduced. Finally, the inverse dynamics equation of the leg mechanism was verified by an example, and the effect of the asynchronous length on the maximum output force of the hydraulic cylinder was analyzed. The moving energy consumption of bionic robot was analyzed according to the inverse dynamic equation. An example showed that the theoretical derivation of dynamic equation was correct. At the moment when the feet landed on the ground, each drive hydraulic cylinder produced the maximum output force, which was independent of the lift height of the leg. When walking in straight and lateral direction, the output force of hydraulic cylinder was increased monotonously with the increase of step length. When walking in the lateral direction of leg mechanism, the maximum output force of the three driving cylinders was lateral swing cylinder, which laid a foundation for the design of buffer structure and dynamic parameters. By analyzing the influence of different gait parameters on energy consumption index of the whole machine, the method of reducing energy consumption was summarized, which provided basis for the gait parameter optimization and trajectory planning of the quadruped robot.

Abstract:The differential pump driven by Fourier non-circular gears has obvious periodic impact phenomenon under load condition, but it does not exist under no-load condition. In order to reduce the impact under load conditions and improve the stability of differential pump, a numerical calculation model of differential pump was established, and the fluid-solid coupling calculation of flow field and driving non-circular gear of differential pump was carried out by numerical calculation method. The calculation results showed that there was a sudden change in the impeller’s torque at the instant of alternating suction and discharge conditions of differential pump. The main reason was the water hammer effect formed when the blade rotated to the inlet and outlet and closed or opened. In order to reduce the impact, microrounded edges of differential pump blades were processed to form a flow field transition zone. The simulation results showed that the periodic torque mutation of the input shaft of the optimized blades was reduced by at least 21.58%, and the pressure distribution of the suction and drainage chambers was more uniform. By verification, it was confirmed that the edge of the differential pump blade had a great influence on the torque characteristics. The maximum variation of the two impellers’ torque was decreased by 51.20% on average. And the optimization of the edge roundness had a great effect on reducing the water hammer effect and improving the impeller torque characteristics.

Abstract:In order to improve the control precision of hydraulic system, the following two aspects were done. Firstly, in terms of driving strategy, the driving strategy was considered and the dynamic characteristics of the valve core under several common driving strategies were analyzed. After considering the following aspects, a multi-stage adaptive voltage excitation driving strategy was put forward accordingly. The strategy had better dynamic characteristics than the commonly used dual voltage excitation strategy. Under this multi-stage adaptive voltage excitation driving strategy, the valve core and the closing time were reduced to 2.2ms and 1.7ms, respectively. At the same time, the coil thermal power was reduced by 68.5%. Moreover, a driving circuit which can output any voltage between 0V and 60V through PWM modulation was designed. Secondly, in terms of control strategy, the BP neural network was used to adjust the PID parameters to achieve precise control of hydraulic cylinder displacement. The network PID controller of BP neural had the characteristics of short response time, small overshoot and good robustness and so on. Under the combined control of adaptive voltage excitation and BP neural network, the hydraulic cylinder displacement error of constant flow hydraulic system was controlled within -0.3~0.3mm. Meanwhile, thanks to the combined control of adaptive voltage excitation and BP neural network, the hydraulic cylinder displacement error of variable flow hydraulic system was controlled within -0.5~0.5mm. The research had a great promotion to the study of this field.