Abstract:The real-time monitoring and control is an essential part of aquaculture, which is one of the important measures to ensure quality safety of aquatic products. After summarizing and collating the existing domestic and foreign research literature, according to the characteristic that domestic aquaculture is mostly in the closed water quality environment, such as ponds and cages, the typical structure of aquaculture water quality monitoring system, the monitoring technology of water quality, the communication technology and intelligent control technology of water quality monitoring system were summarized and compared. The results showed that the real-time online water quality monitoring and sensing technology would be the focus of research. The research of multi-parameter sensor technology based on data fusion would become a research hotspot. The prediction of water quality parameters remained the focus of water quality monitoring research, and nonlinear modeling was the main method for water quality prediction modeling. The low power wan (LPWAN) would soon become the mainstream remote communication mode in aquaculture water quality monitoring system.

Abstract:Aiming at the difficulty in identifying the level of cotton spider mites under natural conditions, an automatic identification method was proposed for rapid detection of cotton spider mites damage under natural conditions. The damaged cotton leaves images collected by mobile phone under natural conditions were used as the object. Firstly, the Otsu method and the regional interconnection marking algorithm were used to separate image of cotton leaf from background. Then, the authors combined the colors, textures, and edge features of the image of damaged cotton spider mites. The support vector machine (SVM) was used to classify the data separately. The average recognition rate of 76.25% was obtained. Finally, it was tried to recognize the mode based on combining the SVM and AdaBoost algorithm to classify the cotton spider mites hazard criteria. With this mode, the average recognition accuracy rate finally reached 88.75%, which was 13.75 percentage points higher than that of BP neural network, 12.5 percentage points higher than that of the SVM algorithm alone and 8.75 percentage points higher than that of the AdaBoost algorithm alone with comparative experiments. In conclusion, it was fully proved that the identification method mentioned can be used to better identify the cotton spider mites damage level, which provided data support for the digital control of cotton spider mites and variable spraying.

Abstract:In order to achieve high-efficiency and low-cost 3D modeling of rapeseed plant and online measurement of phenotypic parameters, a method for rape branch 3D reconstruction and pod identification was proposed by using RGB-D camera. A Kinect sensor was adopted to gather the color and depth images of rape branch from four angles, and then the 3D point cloud of the branch was gained and filtered. A rotation transformation was performed on the point cloud that needed to be registered, and the surface normal vector and curvature of the point cloud were calculated. Point pairs were constituted the points with similar curvature, which were used for the initial registration of the point cloud by using the nearest point iterative (ICP) algorithm based on KD-tree search. Employing the reference value came from the initial registration error, the corresponding point distance threshold of ICP algorithm was adjusted, and then the new point cloud obtained by the initial registration was precisely registered by using the initial registration operation. Combined with the proposed 3D reconstruction and the specific color image processing, an integrated point cloud of the rape branch without the main stem was produced, and then the single rape pod was identified with the Euclidean distance clustering algorithm. The experiment results showed that the proposed method had good robust and realtime, the 3D structure of single pod was clearly visible, the average distance error of the point cloud was less than 0.48mm, and the overall recognition rate of the pod was no less than 96.76%.

Abstract:In view of the low annual precipitation of cinnamon soil in the west of Liaoning Province, the large amount of evaporation, serious soil drought and serious impact on crop yield, a smashing and slashing ridge hoisting machine was designed and studied, which mainly consisted of deep loosening device, smashing and slashing device, ridge device and pressure device. The machine can complete a number of operations such as deep loosening, smashing, rotary tilling, ridge ridges, etc., which can reduce the number of grounding, improve work efficiency, and meet the operation requirements of furrow-ridge and ridge interchange in the brown soil area of Western Liaoning. The kinetic analysis of smashing device of the key components was determined as the rotating radius was 300mm, the depth of grounding device was 8cm, and the minimum speed n was 210r/min. According to the geometric element method design principle of the plow surface, the element angle θ was changed according to the parabola law, the ridge shovel working surface was drawn, and the structural parameters of the ridge device were determined. The wood block experiment of simulating the movement of soil particles through the soil trough showed that the performance of the curved wedge type soil cultivator was better than that of the plane wedge type cultivator, and the ridge and furrow ditches were realized. Through the three factors and five levels test, the main factors affecting the maximum ridge height of the test indicators were the advancement speed of the machine, working depth and straw coverage;the main order of influence of each factor on the working resistance was straw coverage, working depth and the speed of machine. The Design-Expert software was used to solve the working parameters of the machine, and the actual work verified the best operating parameters as follows: the machine forward speed of 6km/h, working depth of 22.2cm, maximum distance of cast soil of 24.05cm, and working resistance of 12.08kN. It satisfied the technical requirements for the construction of reasonable soil layering for the intercropping of ridges and ridges in the brown soil area of western Liaoning Province, and provided reference for the reformation and evaluation of the combined soil preparation machine.

Abstract:Rice is one of the main grain crops in China. Improving the mechanization level of rice production can enhance the comprehensive agricultural production capacity of China. Solid ridge is important guarantee for irrigation and rice growth. It can improve the yield of grain crops and reduce the waste of water resources. In order to improve the efficiency and quality of ridging operation in paddy field, reducing the labor intensity and solving the problem that the ridge can not be built mechanically at the corner of the paddy field, a bi-directional ridger for paddy field was designed, whose rotary tillage and repression components can rotate horizontally. The structural design and working principle were conducted for key components, such as offset system and 180° horizontal rotary adjustment mechanism. Kinematic analysis of the offset system was carried out and the structural parameters of the moving parts were obtained, which satisfied the migration requirements under different working conditions. The motion model of the 180° horizontal rotary adjustment mechanism was established, the conditions for stabilizing the rotary tillage component and compacting assembly were determined. The performance test of the prototype in paddy field was completed. Test results showed that during the advance operation and reverse operation, the average value of the ridge firmness was increased with the increase of interval time and the coefficient of variation of the ridge firmness was decreased with the increase of the interval time when the speed was 1.5km/h, 2.0km/h and 2.3km/h. The average value of the ridge side was higher than that of the top of ridge at the same interval time. The stability values of the measured positions of the ridge were not less than 1332kPa. The two methods of operation met the agronomic requirements of paddy fields and the performance of the ridger was stable in the process of advancing and reversing, its ridge had good quality, which was solid and smooth and could meet the requirement of paddy field production.

Abstract:Aiming to further promotion the accuracy research on the process of the mechanized covering soil on whole plastic film mulching on double ridges. Combined with EDEM software, a discrete element simulation test was carried out on the covering soil friction angle (the repose angle of soil-soil and the sliding friction angle of soil-steel). Through the three-factor orthogonal combination test, the significant order of the contact parameters was obtained, which influenced the repose angle of soil-soil and the sliding friction angle of soil-steel. Based on the software regression analysis of Design-Expert 8.0.6 and response surface analysis method, the relationship between the influencing factors and evaluating indicator (repose angle and sliding friction angle) was established. The measured value of covering soil friction angle (the repose angle of soil-soil and the sliding friction angle of soil-steel) was selected as the chosen target;by using response surface method, the optimal aggregative index could be obtained under the condition that the static friction coefficient among soil was 0.68, the rolling friction coefficient among soil was 0.27, the restitution coefficient among soil was 0.21, the static friction coefficient of soil-steel was 0.31, the rolling friction coefficient of soil-steel was 0.13 and the restitution coefficient of soil-steel was 0.54. In order to verify the reliability of the contact parameters of discrete elements for covering soil on whole plastic film mulching on double ridges, the comparative analysis was made between the simulated test and the actual test of soil friction angle (the repose angle of soil-soil and the sliding friction angle of soil-steel), and the relative errors were 2.6% and 3.1%, respectively. The discrete element method was applied to simulate operation process of the device with covering soil on plastic-film seedbed under the condition of using the optimal contact parameters. The simulation result was consistent with the field test effect. Meanwhile, the parameters calibration method and regression model was feasible, which could provide references for the parameter setting of the soil discrete element simulation of farmland in the northwest arid area of China.

Abstract:The travel speed has great impact on motor driving planting performance. A motor driving planting system with CAN bus control was designed to explore the effect of travel speed on seed meter by using the method of CAN bus communication. The system mainly included an HMI, a planting monitoring ECU and a planting driving ECU, according to the ISO 11783 protocol, the planting machine bus system was designed. A four-channel air suction corn seed metering device was used as the test object, and a test platform was set up to test the bus control speed control accuracy of the seed plate. The problems of long regulation time at low speed and large overshoot in the traditional PID adjustment process were found from the bus extraction data. The piecewise PID parameter control method was adopted to optimize the control results. Based on the experimental results, the speeds of the seed plate were divided into three parts: the low rotation speed (15~20r/min), the middle rotation speed (20~40r/min) and the high rotation speed (40~55r/min). In each part, the PID control set different parameter values. The optimizing system results showed that the average regulating time and the average overshoot were 1.84s and 38.51% with 1.63s and 34.41% decreases, respectively, at low rotation speed, when within the range of 15~55r/min, the absolute value of steady-state error was 0.97r/min on average, the variance was 0.76r/min, and the absolute value of steady-state error was reduced by 0.13r/min on average. In the monitoring planting accuracy test of the bus system, the seed space was 20cm, the number of holes of the seed plate was 26, the travel speed was 4~12km/h, the results showed that the average accuracy of system monitoring was 97.53% with standard deviation of 0.48%. According to the experimental results of the planting bus system performance influenced by travel speed, when the rotational speed of fan was 540r/min and the travel speed was 4~8km/h, the wind pressure was -6.0~-5.9kPa and the mean qualified index of seeding was 95.68% with the standard deviation of 2.29%. When the travel speed reached 9km/h, the qualified index dropped below 90%, and the miss-seeding index was high. The performance evaluation of planting bus system response performance influenced by a step change travel speed was done by monitoring the travel speed and four planting driving motors, when the travel speed was in the range of 4~12km/h with an increment of 2km/h, the average response time of the system to the speed of seed plate was 2.00s with standard deviation of 0.34s. When the travel speed was in the range of 4~12km/h with a decrement of 2km/h, the average response time of the system to the speed of seed plate was 1.83s with standard deviation of 1.07s, the planting bus control system had a short response time when influenced by travel speed step changing.

Abstract:The corn planting model of full straw returning and no-tillage sowing techniques was used in the northeastern part of China. Due to the thick and abundant maize straws, limited the quality and efficiency of sowing operations and reduced crop yield, the concave disk row cleaners with star-tooth capable of efficient straw cleaning in whole straw mulching fields were designed. The kinematic pattern of straw particles at surface of disc row cleaner during the operation was clarified through the use of theoretical analysis, the main structural parameters affecting the operational quality of the row cleaners were clarified, and the range of values of each parameter were determined. Combined with rotational orthogonal test design and EDEM discrete element simulation technology, the optimal structural parameter combination of the row cleaner was achieved. The performance of the row cleaners was verified by field comparison test. The results showed that the main structural parameters affecting the performance of the device were radius of gyration of the disk, projection length of disk camber and radius of curvature. When the radius of gyration of the disk was 152.5mm, the projection length of disk camber was 50.9mm,and the radius of curvature was 160mm, the working performance of the row cleaners was the best, and the straw cleaning rate and working resistance were 92.2% and 142.6N, respectively. The working performance of the row cleaners was better than that of the plane row cleaners, and the operation quality was stable, which satisfied the agronomic and technical requirements of no-till planting.

Abstract:In the view of low efficiency and quality and high labor intensity of Salvia miltiorrhiza tilted transplanting on mulch-film by artificial transplanting，the existing transplanter is not suitable for tilted transplanting of Salvia miltiorrhiza on mulch-film，and combining with the agronomic requirement of high efficiency production technology of Salvia miltiorrhiza big-ridge double-row on mulch-film，a duck-billed tilted transplanting mechanism for Salvia miltiorrhiza was designed based on deformed elliptical gear-double variable speed crank five-bar mechanism. On the basis of trajectory，tilted gesture of planting apparatus and design requirements which was required by transplanting mechanism，the working principle of the mechanism was analyzed and the theoretical model of mechanism was established. The visual auxiliary programs for human-computer interaction was established by using Matlab（Matrix Laboratory） dependeding on the theoretical model. With the help of auxiliary programs，the influence rules of parameters for mechanism on tilted angle and endpoint motion trajectory of planting apparatus were studied，the human-computer interactive method was used to get the parameters combination suited for agronomic requirements tilted transplanting mechanism on mulch-film of Salvia miltiorrhiza. According to the optimized parameters combination，the prototype was designed for virtual simulation and prototype field experiment. Prototype experiment showed that the deformed elliptical gear-double variable speed crank five-bar tilted transplanting mechanism of Salvia miltiorrhiza on mulch-film could meet the agronomic requirements of Salvia miltiorrhiza tilted transplanting on mulch-film while ensured the quality of operation，the seedling angle qualification rate was 90.7%，the leakage rate was 2.7%，the plant spacing variation coefficient was 5.6%，and the planting depth qualified rate was 93.7%.

Abstract:In order to improve the screening performance of the air-screen cleaning device of maize grain harvester, the relationship between the motion of grain on the screen and the function f(x) of screen-shape was determined through the mechanics analysis of particle. In order to propose a type of sinusoidal-shape screen, the woven screen was studied. Computational fluid dynamics and discrete element method (CFD-DEM) were coupled to compare and analyze the airflow in the cleaning device and the characteristics of flat, convex and concave screening. The screening performance of the sinusoidal-shape screen, compared with this one with tail screen was removed, was better. The quadratic orthogonal rotational-combinational simulation tests were designed. The coefficient of screen-shape and the inlet velocity of airflow and the direction angle of airflow were taken as factors, and the loss and cleanliness of maize grains collected were taken as indexes. The regression mathematical models between factors and indexes were multi-objective optimized by using Design-Expert software. The best combination of parameters was obtained, including the coefficient of screen-shape of 32.35mm, the inlet velocity of airflow of 13.73m/s, the direction angle of airflow of 23.86°. The best combination of parameters was set in the bench test. The flat weave screen was compared with that of the screening performance of sinusoidalshape screen. The experimental results showed that the sinusoidalshape screen can realize the fast passage of maize debris, and increase the possibility of maize grains passing the screen when the total feeding quantity was 5kg/s and the vibration frequency of the screen was 5.15Hz. The working mechanism and screening performance of the sinusoidal-shape screen were tested by highspeed camera and indoor bench. The experimental results showed that the state of movement of maize mixture on different screens was more favorable to the performance of the cleaning device. The cleaning rate of maize grains collected was 98.07% and the rate of maize loss was 1.16% after screening. Compared with the flat weave screen, the cleaning rate of maize grains was increased by 2.45 percentage points and the rate of maize loss was reduced by 0.79 percentage points, which met the requirements of technical specification for quality evaluation of screening in China.

Abstract:Fodder rapeseed is a good quality feed crop, and it can effectively alleviate the problem of lack of green feed for livestock in winter and spring. Because of high water content and crispy texture of fodder rapeseed, there is a lack of applicable harvesting machinery in Midlower Yangtze River. To solve the problems, a kind of cylindertype chopping device was designed. The structure and operation parameters of chopping device were analyzed through material properties and the requirements of cutting and throwing operations. Single factor experiment and rotation regression design were carried out to study the effects of feeding roller and cutterhead rotational speed on length qualified rate and power. The regression equation of the relationship between feeding roller and cutterhead rotational speed, and the length qualified rate and power was obtained. The results showed that the length qualified rate was better when the feeding roller rotational speed was 400~550r/min and the cutterhead rotational speed was 600~800r/min. The optimum operation condition was: the feeding roller rotational speed was 496.17r/min, the cutterhead rotational speed was 709.14r/min. Under this condition, the length qualified rate was 91.16% by calculation. What was more, the field experiment of fodder rapeseed harvester was conducted. It turned out that the cylinder-type chopping device worked well and the length qualified rate met the requirements of feeding. The results could provide support for optimization of the cylinder-type chopping device and the improvement of the overall structure for fodder rapeseed harvester.

Abstract:When the plant protection UAV is used to spray pesticides on orchard, the spatiotemporal distribution of downwash airflow inside and around the canopy has a major impact on the adhesion and distribution of the droplets. In order to clarify the spatiotemporal distribution of downwash airflow inside and around the canopy of trees when applying multirotor plant protection UAV to spraying, combining RANS equation, RNG k-ε turbulence model, porous model, sliding mesh technology and SIMPLE algorithm, a three-dimensional CFD model for the spatio-temporal distribution of the down-wash airflow of six-rotor plant protection UAV in hover was established. The results of numerical simulation showed that when without tree, the downwash airflow of the rotor developed downward was approximately in a “cylindrical” shape, and formed the ground spreading after reached the ground, and the “Z-direction (vertically downward) speed stable region” appeared in the region of 0.6~1.7m below the rotor, where the speed range was from 3.0m/s to 4.0m/s. When tree existed, the canopy had an obvious effect on blocking the downwash airflow of the rotor, and it would not appear “Z-direction speed stable zone”. Taking the three trees simulated as an example, the airflow around the canopy of No.Ⅰ tree began to develop downward from the upper part of the canopy in a “conical” shape, and developed to the ground at an inclined angle to form a small area of ground spread. There was a nearground hoisting at the end of the ground spread. The airflow around the canopy of No.Ⅱ and No.Ⅲ trees was heavily hoisted, and it did not have obvious ground spread in the calculation area;the maximum speed in Z-direction was close to 8m/s directly below the rotor center. With the increase of canopy pressure loss coefficient, the speed attenuation in Z-direction was accelerated, while the rotor airflow was spreaded around. Calculating the maximum speed decay ratio in Z-direction inside the canopy, it was found that the maximum speed decay ratio in Z-direction in the canopy of No.Ⅰ, No.Ⅱ and No.Ⅲ trees was increased successively except the No.Ⅲ lower part of the canopy. The relative errors between the test values and the simulated values at 0.3m, 0.8m, 1.3m and 1.8m below the rotor and 2.3m near the ground were less than 10% and not more than 25%, respectively. The overall goodness of fit was 0.9846, and the numerical simulation was accurate. The test results of down-wash airflow speed of trees showed that the airflow speed distribution inside canopy of the experimental tree was in good agreement with that of the simulated tree.

Abstract:In order to solve the problems of unreasonable pesticide application methods and relatively simple control methods in the spraying process of large-scale wide-width spraying machine, a multireflux variable spraying control system was designed based on the 3WP-1200 spraying rod spraying machine with 22m spraying width. The control system could adjust the proportional control valve according to the running speed of the sprayer, which realized the variable spraying by changing the spray flow rate caused by the opening of return port. The control system was divided into five paths to control all sprinklers, and each path could be controlled separately. When one or more routes were disconnected, the corresponding return port could be opened, so that the spraying quantity of the other sprinklers would not change without changing the flow rate of the system. At the same time, its multi-reflux control method made the system pressure more stable and control precision higher. Moreover, the hardware and software of the system were designed, and the liquid level calibration and spray accuracy test of the control system were carried out. In the liquid level calibration test, the liquid volume corresponding to different liquid levels was calibrated, and the determination coefficient R2 of the calibration model was 0.994. In the flow control accuracy test, the target flow rate of a single sprinkler had little difference from the actual flow rate, and the relative error was not more than 4.1%. In the spraying control test, the spraying flux could vary with the speed, but the actual spraying flux was almost the same as that of the set spraying flux, and the relative error was within 6%. These experimental results showed that the system could achieve variable spraying with high control accuracy.

Abstract:In order to improve the efficiency of watersaving irrigation in agriculture, the round rotatory jet sprinkler was proposed. The CFD numerical simulation method of the sprinkler was determined. Depthtowidth ratio (k/w), potential difference ratio, split distance ratio and side wall angel were selected as the experimental factors, and frequency of wallattached switching and flow amplitude were taken as the indexes. The optimum structure of internal channel of sprinkler was obtained by orthogonal test. By means of highspeed photography technology, the frequency of wallattached switching of jet was measured, and the inlet flow rate of sprinkler was monitored. The results showed that the simulated flowpressure relation was basically consistent with the experimental results. The relative error range was from 2.1% to 4.0%, and the variation trend of the frequency of wallattached switching of jet with the inlet pressure was basically the same, and the relative error range was from 7.7% to 22.2%. When the inlet pressure was 0.15MPa, 0.20MPa and 0.25MPa, the hydraulic properties of PY210A impact sprinkler and jet sprinkler were studied, respectively. The flow rate of jet sprinkler was small (1.19~1.53m3/h), and the range was long (13.0~15.7m), the sprinkler irrigation intensity was small (2.85~3.63mm/h), and the rotation period was short (81~105s). The precipitation of impact sprinkler was “saddle”, the precipitation near and far away was relatively large, the precipitation of jet sprinkler was “triangle”, and the precipitation was decreased with the increase of range. The research provided a reference for the structure design and hydraulic performance optimization of the round rotatory jet sprinkler.

Abstract:During the growth and breakup of cavitation, thermodynamic effects will influence cavitation on water at different temperatures and cryogenic fluid. Combined Antoine equation and considered the change of saturated vapor pressure caused by latent heat of vaporization and impact of turbulent energy turbulence kinetic energy on local vaporization pressure, three kinds of cavitation models (Zwart, Merkle and Singhal) were modified. The hydrofoil NACA0015 at different water temperatures was numerically simulated by using three cavitation models and modified models. The conclusion showed that the simulated result of modified Merkle model was more consistent with experimental data. The HORD hydrofoil at different liquid nitrogen temperatures was numerically simulated based on the modified Merkle model. The results compared with experimental data showed that temperature and corresponding saturated vapor pressure were decreased in the cavity, leading to cavitation intensity decreased, the cavity length shortened and local cavitation number was over far field cavitation number. The liquid nitrogen temperature at 83.06K compared with it at 77.64K was more sensitive to thermodynamics, the pressure drop was larger and the cavitation intensity was weaker. The results can provide a new correction method of cavitation model for studying cavitation of water and cryogenic fluids at different temperatures. In addition, the modified cavitation model was of great significance for studying the thermodynamic effects in the cavitation process and it can be applied to cryogenic cavitation in engineering problems.

Abstract:In order to solve the problems of non-contact displacement measurement, widerange and high sensitivity measurement in agricultural machinery equipment, a non-contact optical fiber displacement sensor based on Peanut-shape Michelson interference structure was proposed. The Peanut-shape fiber Michelson interference principle was analyzed, and the sensor structure combining the magnetic field and the Peanut-shape structure in fiber-type Michelson interference was designed, and by simulating the magnetic field, the magnetic field strength curve was obtained, theoretical analysis shows that a good sine wave can be obtained within the range of 1~3mm between the sensing detector and the magnetic scale. While there is a distance range from 0mm to 1mm, due to the large contact area, a sawtoothlike wave is obtained, according to results of theoretical analysis, the distance between the experimental sensor head and the magnetic scale is determined. The strain calibration system and a displacement test system of sensor were established. Experimental result showed that the Peanut-shape Michelson interference fiber sensor strain sensitivity reached 1.82pm/με, which was 1.5 times of that of bare fiber, and the linearity was 0.997;the spectral curve obtained by the displacement test was consistent with the magnetic field simulation curve, displacement measurement can be achieved, and linear fitting degree was 0.999. By encoding the permanent magnets, the direction of motion can be discerned.

Abstract:The suitability of rural residential area distribution is related to the spatial structure stability of rural settlements and the development suitability of villages. It is conducive to promoting rural residential area distribution optimization and sustainable development to coordinate the spatial structure of rural settlements and the village development. According to catastrophe progression model, taking Mengzhou City as sample area, the suitability of rural residential distribution was evaluated from two aspects, spatial structure stability of rural residential areas and the suitability of village development, and the coupling coordination degree was measured between the two evaluation targets according to the coupling coordination degree model. Furthermore, the following results were obtained: the spatial structure stability of the whole rural settlements in Mengzhou City was relatively high, while the stability of village spatial structure in hilly region was low. The villages of Mengzhou City had a wide gap in development strength which highlighted that the development suitability of villages in the northwest of Mengzhou City was weak, while the villages in Xiguo Town, Nanzhuang Town and Huagong Town were more suitable for development. The overall coordination degree of rural residential distribution in Mengzhou City was low, which showed that the highly and moderately coordinated rural residential areas accounted for 26.90% of the total rural residential area, and that of the low coordination type was 72.60%. There were four villages on the verge of being disfunctional. Through a comprehensive analysis of the evaluation results, the layout of rural settlements in Mengzhou City was divided into five optimization patterns, including priority construction type, general development type, reservation type, industrial introduction type and strengthening transformation type. It can provide a scientific basis for the renovation of rural residential and village planning under the background of rural revitalization.

Abstract:Accurately mastering the planting area and distribution of the seed maize field can provide more accurate data for regulatory authorities, and timely detection of illegal seed production areas. According to the differences of high temporal phase spectrum, high spatial texture and shape of features, the identification of maize seed production field was carried out based on 163 ground samples, multisource sequential optimization of vegetation index set and texture analysis of high spatial resolution remote sensing images. Through correlation analysis, six vegetation indices (VIs) of the normalized difference vegetation index (NDVI), enhance vegetable index (EVI), normalized difference water index (NDWI), triangle vegetation index (TVI), ratio vegetable index (RVI) and difference vegetation index (DVI) were identified from eight VIs reflecting different growth conditions of vegetation. And the random forest (RF) classification algorithm was used to identify the seed maize field. The graylevel co-occurrence matrix (GLCM) texture feature system was constructed by using the 0.7m Kompsat-3 image of tasseling stage. It contained five texture features: mean, entropy, contrast, angular second moment (ASM) and homogeneity. At the same time, Subtract texture features were proposed in order to reflect the characteristics of the intercropping of corn parents. Before constructing the texture feature system, local binary patterns (LBP) processing on the image was performed to solve the directional problem of crop planting texture in the image. The random forest was used to identify the seed maize field from maize field classification results. Qitai County in Xinjiang Uyghur Autonomous Region was taken as a research area to verify the proposed method, the results showed that the user’s accuracy and mapping accuracy of the seed maize field was 99.19% and 93.34%, respectively. The research result can provide further technical support for the monitoring and supervision of hybrid corn farming in China.

Abstract:Phenological information is vital for dynamic monitoring of crop growth and precision field management. Accurate extraction of phenology benefits a rational analysis of crop’s inter-annual changes in time and space and provides the fundamental data for monitoring of crop growth and crop yield forecasting. Winter wheat planting areas in Hebei, Henan, and Shandong Provinces were taken as study locations. Firstly, the LAI time series in 2015 was smoothed with Savitzky-Golay filtering algorithm, and the day of the maximum value from time series of LAI was taken as heading period. The Savitzky-Golay filtered MODIS LAI was fitted by using the double Logistic function. The day corresponding to the largest second derivative of Logistic LAI curve was considered as the green-up period. Jointing and flowering periods of winter wheat were extracted based on effective accumulated temperature from the existing greenup and heading stages from 2012 to 2014. The method was validated by the observations of phenology at agrometeorological stations in 2015 and the results showed that the phenology agreed well with the observational data of winter wheat. The second derivative method was quite sensitive to mixed pixel and accuracy of Logistic function’ fitting of MODIS LAI. Generally, the extracted greenup stage was delayed, while the extraction of the jointing, heading and flowering stages achieved a high accuracy.

Abstract:After mining in the high ground-water level mining area, the surface subsided and accumulated water. The surface is changed from the farmland ecosystem to the water-land two-phase ecosystem. As the energy fixers and nutrient producers in the wetland ecosystem, wetland vegetation can reflect the changes in the wetland ecological environment. Vegetation classification is the basis for exploring vegetation coverage and monitoring dynamic changes. In order to grasp the type and spatial distribution of vegetation in coal mining subsidence and promote land use, management and restoration in mining area, totally 3304 working face of Dongtan Coal Mine in Jining City, Shandong Province was selected as the study area. The UAV multi-spectral images were taken as data sources, and the object-oriented classification method and supervised classification method were used to classify the wetland in the study area. Based on the optimized object-oriented scale segmentation parameters, the classification rules were determined and then the object-oriented classification model was constructed to classify the wetland vegetation and generate the vegetation distribution map. At the same time, totally 322 sampling points were used to verify the accuracy of the classification results. The results showed that the overall accuracy of the supervised classification method was 44.3%, and the object-oriented classification method was 84.2%. Compared with the supervised classification method which based on pixels, the object-oriented classification method improved the classification results and significantly improved the image classification accuracy. The Kappa coefficient of supervised classification was 0.4, while the Kappa coefficient of object-oriented classification was 0.8. The research result provided a new method and basic data for the investigation of wetlands in coal mining subsidence area and the study of the spatial distribution of vegetation under the influence of mining subsidence.

Abstract:To simulate the ecological land transition of Baotou City, Inner Mongolia, the MCR-ANN-CA model was built. This model was composed of minimum cumulative resistance model (MCR), artificial neural network (ANN） and cellular automata model (CA). The MCR model was used to simulate the resistance faced by ecological land during its transition. To measure the resistance, the data of normalized difference vegetation index (NDVI), digital elevation model (DEM), slope, distance from water, population density and industrial park distribution were normalized and superimposed to produce the resistance surface of MCR model. Then a cumulative consumption resistance surface was generated by using the cost distance tool of ArcGIS software. The generated surface was taken as the suitability map of CA model. The ANN model was used to extract CA neighborhood transfer rules and consider the neighborhood land use structure. The CA model combined the cumulative consumption resistance surface and the neighborhood transfer rules extracted by using the CNN model. And the MCR-CNN-CA model was finally formed. Based on the land use data of 2006 and 2011, the transition of construction land of Baotou City in 2016 was simulated by using the MCR-ANN-CA model. The simulation result of the model was compared with the CA-Markov model. The Kappa index of agreement (KIA) of the two models were 0.89 and 0.87, and the relative errors were 3.10% and 5.31%, respectively. The MCR-ANN-CA model showed high simulation precision.

Abstract:Hyperspectral remote sensing technology is a powerful tool in the analysis of soil compositions as well as soil physical and chemical properties. Totally 385 natural soil samples were collected from cotton fields in North Xinjiang Province, the selected soil samples according to the total nitrogen content were processed by 2mm, 1mm, 0.5mm and 0.15mm sieves, and their spectral reflectance characteristics were measured. After the transformation of spectral data with twelve forms, the spectral inversion models of soil nitrogen content were established based on support vector machine (SVM), partial least squares regression (PLSR) and stepwise multiple linear regression (SMLR), and the accuracy and universality of the model were tested. The results showed that there was no significant correlation between the original spectral characteristics and soil nitrogen content, and which can be improved by different data transformations. In the same data transformation, there was no obvious difference in the band position corresponding to the maximum correlation coefficient in different particle size processing. According to the fitting accuracy of different particle size treatments, the smaller the particle size of the sieve was, the higher the precision of the total nitrogen content was, the optimal fitting models of the three methods were all processed by 0.15mm sieve treatment, the SVM method used (lgR)′ transformation, the model R2c was 0.8987, the RMSEc was 0.0181 and the RPD was 2.7049, the PLSR and the SMLR methods used R′ transformation, the R2c were 0.8520 and 0.8196, the RMSEc was 0.0413 and 0.0436, and the RPD was 2.5549 and 2.4374, respectively. The optimal model was checked with the samples which were not involved in building model and the R2 of SVM, PLSR and SMLR were 0.8829, 0.7715 and 0.7054, respectively. From the prediction error of the model, the lower the soil total nitrogen content was, the greater the prediction error was, it was impossible to accurately estimate the soil total nitrogen content by spectral reflectance characteristics.

Abstract:The gross primary productivity (GPP) of terrestrial ecosystems is an important component of the carbon cycle of terrestrial ecosystems. Accurate calculation of GPP helps to understand the response of terrestrial ecosystems to climate change and human activity. In order to more accurately and comprehensively grasp the carbon sequestration of global terrestrial ecosystems, the simple linear model proposed by GUANTER was improved. Using FLUXNET2015 flux data, GOME-2 chlorophyll fluorescence data, MODIS vegetation index products and land cover data, temperature stress factors and saturated water vapor stress factors were added to the model. The estimated results of the simulation were improved compared with the estimates of traditional simple linear model. Among the 13 flux sites, the estimation accuracy of 10 flux sites was improved. In addition, in order to further improve the estimation accuracy of the model, canopy escape rate of chlorophyll fluorescence was also simulated based on the model incorporating environmental impact factors. The results showed that the estimation accuracy of all 13 flux sites was improved compared with the estimates of traditional simple linear models and models incorporating environmental impact factors. In conclusion, the addition of environmental impact factors and vegetation indices to traditional linear models improved the estimation accuracy of the model.

Abstract:In order to explore the new monitoring sampling technology suitable for the situation of forest resources in China, based on the annual monitoring technology of forest resources in the United States, the annual monitoring of forest volume was researched in Yanqing District, Beijing. Firstly, according to the actual situation of forest resource distribution in research area and based on the design of American annual monitoring system of forest resources, some optimization and improvement in the size of hexagonal sampling frame and sampling rate were done, and a system sampling scheme for annual forest inventory monitoring was designed. The result showed that using the positive hexagonal sampling frame to do annual monitoring of forest resources can receive an optimal scale area, an optimal side length and an optimal sampling fraction, and the amount was 2338hm2, 3000m and 66%, respectively. According to the systematic sampling scheme, and combining with field investigation, the volume amount received in Yanqing was 16.6m3/hm2, the sampling monitoring accuracy was 85.4%, which was all conformity with NFI Technical Regulations. Therefore, the feasibility of the proposed forest resource monitoring scheme based on cluster sampling technology in China was verified. The main points of cluster sampling technology and the method of forest accumulation amount output based on circular cluster were introduced in detail. The research result can provide reference for the optimization and improvement of the national forest resources continuous inventory system and the field sampling survey technology.

Abstract:During the operation of traditional disc filter, the head loss is steeply increased, and it is easy to reach complete clogging in a short time, which affects the filtering effect. The existing research focuses on the improvement of its macrostructure, and there are few studies on the optimization of disc flow path structure. A fractal theory was introduced into the design of disc filter along flow path. A new type of disc filter was proposed, and compared with the traditional disc filter at home and abroad on the performance of head loss, sand interception, d50 and the uniformity of sediment distribution in the runner. Based on the experimental comparison, the clogging uniformity index ηu, was introduced, and it was desirable to determine the clogging uniformity by quantitatively characterizing the change in head loss during the operating period. The results showed that the local head loss of the new disc filter under the condition of clear water was 12%~20% lower than that of the traditional disc filters, under the condition of sandy water, the head loss of the new disc filter was uniform with time and lower than the growth rate of the traditional disc filter;under the condition of different concentrations of sandy water, the average sand interception of the new disc filter was 11%~54% higher than that of the traditional disc filter, the average d50 of the intercepted sediment was 39.51μm, which was smaller than the traditional disc filter of 59.04~87.60μm. The research can provide theoretical and experimental basis for the feasibility and superiority of fractal theory applied to disc structures.

Abstract:In order to explore the effect of water saving irrigation pattern on water distribution and lodging resistance of rice plants, a test was carried out in Qing’an County, Heilongjiang Province from May to October 2017. Three treatments were set: drip irrigation dry direct seeding (DH), flood irrigation in dry land (MH) and conventional basin irrigation (CK). The results showed that the moisture content of the total wet base of crown and leaf, sheath and stem treated by DH and MH was lower than that of CK at full growth stage, but the moisture content of root wet base was higher than that of CK at the end of tillering stage. The moisture content of different internodes (W), internode length (L) and plant height in the stems of milk ripening and yellow ripening stage were the lowest in DH, and the CK treatment was the highest, but the unit internode weight (Uw) of stem was the largest in DH, and the CK treatment was the smallest. Compared with CK, DH significantly improved the flexural force (F), broken bending moment (Bm) and bending stress (Bs) of rice stem, and reduced the bending moment (Wp), crosssection modulus (Z) and lodging index (Li), indicating that the drought resistance of rice was significantly improved by drip irrigation and dry direct seeding. The correlation between different parameters showed that L, W, Wp, Z and Li showed significant positive correlation (P<0.01), while Uw, F, Bm, Bs and Lishowed significant negative correlation (P<0.05), and the moisture content of the wet base of rice stems had significantly positive correlation, indicating that the water content of stems could be used to characterize and predict the lodging index of rice. The research results can provide new methods and ways to solve the problems of rice lodging and low water efficiency in the black soil area of Northeast China. It was of great significance to ensure the grain yield and the sustainable utilization of agricultural water resources in the black soil area of Northeast China.

Abstract:The saline/sodic soil in the coastal reclamation area of Jiangsu Province was taken as the subject investigated. Based on Micro-CT scanning technology, the changes in total porosity, soil water characteristic curve and unsaturated hydraulic conductivity of saline/sodic soil after applying biochar were analyzed and the soil hydraulic properties were predicted based on fractal models. Therefore, the effects of biochar application on soil structure and hydraulic characteristics in coastal reclamation area were revealed. The surface soil (0~20cm) was amended by thoroughly mixed biochar with three levels of application rates (0, 2% and 5% by mass of soil) in a completely randomized design with three replicates for each treatment. The results showed that bulk density of soil was significantly reduced and total porosity and macroporosity of soil were increased obviously after applying 5% biochar. Besides, the proportion of waterstable aggregates with size greater than 0.25mm, the fractal dimension of soil pores was significantly increased. The saturated water content and saturated water conductivity of soil were also improved. Combined with the Micro-CT scanning technology and the fractal theory, the water characteristic curve and the unsaturated hydraulic conductivity of the improved saline/sodic soil were predicted. The accuracy of the prediction was high, which can be used in the study of practical problems.

Abstract:Soil nutrient availability is an important factor influencing heavy metal enrichment plant. The characteristics of soil nutrient slowrelease and the tendency of cadmium accumulation of mustard were studied. A complete combination design of fertilization rate (0, 20%, 40%, 70% and 100% of the benchmark fertilizer application amount respectively, and the benchmark fertilizer application amount was N350kg/m2, P2O5 180kg/hm2 and K2O 180kg/hm2) and carbon application ratio (carbon fertilizer quality ratio of 0, 3% and 9%) were set up in the experiment. The results showed that the soil nutrient slowrelease characteristics and cadmium enrichment trend were well fitted based on the Logistic curve model, and the measured root mean square error ratio was 3.29%~8.37%, and R2 was no less than 0.9570. The fertilizer proportion of soil nutrient with high efficient and slowrelease under combined application of carbon fertilizer was 0.99%~55.18%, the maximum sustainedrelease efficiency of nitrogen and phosphorus was increased by 49.17%~90.00%, 13.25%~37.35%, respectively, and the soil nutrient content was increased by 17.38%~40.93%, compared with that without carbon application. The biomass of mustard with cadmium concentration was increased by 119.65%~263.36% through efficient slowrelease of soil nutrients, and the maximum efficiency value of the biomass in the aboveground part was increased by 166.67%~300.00% compared with the biomass in the root part. The content of cadmium and enrichment coefficient of mustard greens was increased by 97.79%~201.96% in the highly efficient slowrelease interval of soil nutrients. Therefore, in order to meet the requirement of both high efficiency and high concentration of mustard cadmium and fertilizer conservation, the combined application strategy of carbon fertilizer was optimized as follows: the proportion of nitrogen, phosphorus and potash fertilizer under 9% carbon was 60.58%, 61.32% and 21.48%.

Abstract:Plant root exudate plays an important role in the process of material exchange between plant and soil. Moreover, it is a significant factor in ‘plantmicroorganisms’ interactions. The process of interaction between Bacillus amyloliquefaciensL-S60 and cucumbers was analyzed. The utilization and chemotaxis of the main components of cucumber root exudate, organic acids and amino acids, by L-S60 were studied. After establishing the interaction model between the strain and the cucumber seedlings, the coloning of root surface in hydroponic culture was studied via counting the strain by time. Furthermore, the genes related to root colonization, swarming motility and biofilm formation on translational level were analyzed by fluorescent quantitation PCR. The results showed that L-S60 could utilize the main organic acids (citric acid, oxalic acid, succinic acid and malic acid) and amino acids (glutamic acid, phenylalanine, cysteine and tryptophan) from cucumber root exudates and provide well utilization of malic acid and glutamic acid. Also, L-S60 showed the chemotaxis toward these components and could be strongly attracted to malic acid and glutamic acid. According to the CFUs, which could colonize on the root surface, and the relative quantitative expression of the related genes on translational level, L-S60showed strong colonization capacities on the cucumber root surface and the most amount of colonization was 1.02×105CFU/g. In conclusion, L-S60 showed great potential to become a biological control agent of practical applications in the future. 

Abstract:The photosynthetic product accumulation of cucumber, which is related to temperature, carbon dioxide concentration and light intensity, shows high correlation with the photosynthetic characteristics of different leaf positions. The dynamic acquisition of light parameters in different leaf positionsis a key problem to be solved in the optimization and regulation of stereo light environment of facility cucumber.A stereo light environment optimization control modelwas proposed based on multiintelligent algorithm for cucumber, a multifactor nesting experiment was designed to obtain multidimensional sample data, and a regression support vector machine photosynthetic rate prediction model, which coupled leaf position, temperature, light intensity and carbon dioxide concentration was constructed. Based on the particle swarm optimization algorithm, the light saturation point of different leaf positions was obtained under different environmental conditions. The regression support vector machine algorithm was used to construct the stereo light environment optimization control model for the target light intensity. The verification results showed that the proposed method can dynamically calculate the target light intensity with different environmental factors of different parts of the whole crop. The coefficient of determination was 0.9993, and the root mean square error was 2.349μmol/(m2·s). The relationship between leaf chlorophyll content and photosynthetic characteristics of different leaf position was further analyzed, and the strong correlation between the two was proved. The research result had important significance for improving the efficiency of stereo light environment regulation of facility vine crops.

Abstract:The IoT monitoring products are widely used in greenhouse production, which could generate massive data. The existing data fusion algorithms for greenhouses had low fusion accuracy and weak generalization capability for high-dimensional features and mixed features (combined with sparse features and continuous features). It was rare to use the deep learning model to top-level fusion of greenhouse data and provide accurate decision information. Aiming at the above problems, a two-level greenhouse environment data fusion algorithm was proposed based on wide-deep neural network (WDNN). Firstly, integrating multipoint multi-features mixed data in the greenhouse and marking the data categories. Then the constructed training set and test set were input into the WDNN deep learning model for 2000step iteration training. The model structure was set as 7-100-50-7, the output form was multipoint single feature, which was the first-level fusion result as decision information of each area of the greenhouse, and then the output data was secondlevel fusion according to the minority obeyed majority principle, and the overall evaluation decision of the greenhouse environmental state was obtained. For comparison purposes, the other three fusion models were trained as deep neutral network (DNN), BP neural network (BPNN) and random forest (RF). The experimental results showed that the loss value of the initial segment of the WDNN network was higher than that of DNN network, but the loss function curve had a faster rate of decline and the model parameters were better. The accuracy of the model after training was 4.32 percentage points higher than that of DNN, but the training time was increased by 21.36%;the accuracy of BPNN model was 82% and its parameter optimization was the slowest, parameter optimization required more iteration steps;RF model training speed was the fastest, but its model fusion accuracy was 3.39 percentage points lower than that of WDNN. The fusion accuracy was insufficient;above comparison results proved that it was feasible and excellent to use the WDNN model to fuse the mixed data in the greenhouse. Inputting the mixed situation information contained the sensor anomaly and meteorological data under various conditions into the fusion system, then the context decision rate reached 98.90%. The realization of the WDNN fusion system could be used to monitor greenhouses with more parameters and more complex environments, and enrich the fusion feature categories while ensuring the accuracy of decisionmaking. It could further improve the intelligence degree of the greenhouse fusion system.

Abstract:Based on the shortcomings of existing reactors in ex-situ catalytic pyrolysis of biomass vapors, the guide vane type cyclong reactor was designed. The gradient distribution and residence time distribution of solid phase in the reactor were studied by using computational fluid dynamics method and pulse tracer experimental method. The research could provide an important theoretical basis for technology improvement of ex-situ biomass catalytic pyrolysis and further design of the reactor. The simulated model was confirmed to be right by comparing with the results of the experiment. The results showed that the gas-solid two phases had good mixing contact and separation effects under the action of the Coriolis and centrifugal force in the vortex flow field of different intensities, which provided a key precondition for the realization of reaction separation integration process in the reactor. When the catalyst particle diameter was 10μm and the catalyst to gas ratio was 10.5, the optimal mixing and separation effect of the reactor was achieved. The residence time distribution curves of catalyst particles showed a smooth single peak distribution with small trailing tail, and the average residence time was 1.055~1.235s. The flow pattern of catalyst particles in the reactor was close to the plug flow.

Abstract:It is of great practical significance to rapidly analyze the content of potassium (K) and sodium (Na) in wheat straw for improving its combustion efficiency. And totally 29 representative wheat straw samples collected from North China were chosen as the research objects. Based on the standard values measured by inductively coupled plasma mass spectrometry (ICP-MS), laser induced breakdown spectroscopy (LIBS) was used for the quantitative analysis of K and Na contents in wheat straw. In order to improve the accuracy of quantitative analysis, the spectral bands around the analytical lines of K and Na were primarily confirmed as original spectral data of the calibration models, respectively. The effects of baseline correction (BC), normalization (Norm) and meancentering (MC) on LIBS spectral denoising were compared. Moreover, the applicability of partial least squares regression (PLSR) and Adaboost backpropagation artificial neural network (BP-ADaboost) for preprocessed spectral data was compared and analyzed. Results showed that when compared with PLSR models, the BP-ADaboost models of potassium and sodium in wheat straw both had better effects, yielding R2p of 0.908 and 0.979, root mean square error of prediction set of 2.388g/kg and 0.138g/kg, relative percent deviation of 2.358 and 4.203, respectively. Therefore, LIBS technique can be used for the simultaneous quantitative analysis of K and Na in wheat straw.

Abstract:Super absorbent resin was prepared by graft copolymerization of hydroxypropyl methylcellulose (HPMC) with acrylic acid as graft copolymer, ammonium persulfatesodium bisulfite as initiator and polyethylene glycol diacrylate as crosslinker under microwave radiation. The absorbent ratio, absorbent rate and crosslinking rate of super absorbent resin were studied. The water retention properties and IR spectra, thermogravimetric and apparent morphology were characterized. The results showed that the optimum preparation methods were as follows：the mass ratio of HPMC to acrylic acid was 1/7, the neutralization degree was 65%, the mass ratio of initiator to acrylic acid was 1%, the mass ratio of crosslinking agent to acrylic acid was 0.4%, and the reaction time was 4min and 30s. Under the optimum preparation conditions, the water absorption ratio of HPMC super absorbent resin could reach 497.13g/g and the salt absorption ratio was 61.70g/g. This hydroxypropyl methyl cellulose based super absorbent resin could absorb liquid to reach the state of preservation in 30min quickly. The super absorbent resin could retain water for more than 48h at 35℃, 6h at 55℃ and 5h at 75℃. After six times of reuse, the water absorption rate of the super absorbent resin could still reach 69.7% of the initial water absorption rate, and the salt absorption rate could still reach 44.2% of the initial salt absorption rate. The super absorbent resin had good reusability. Thermogravimetric analysis showed that the super absorbent resin had good stability at 330℃. The hydroxypropyl methyl cellulose based super absorbent resin had good water absorption, salt resistance, high water retention rate and excellent reusability.

Abstract:Jujube is a high-value fruit throughout the world. Detection for the surface defects of jujubes is the prerequisite to realize its automatic grading. For the difficulty of red jujube location and defect detection in images, a kind of locating method based on search of the shortest path between frames and framework named ensemble-convolution neural network (E-CNN) were introduced. As for locating method, image coordinate system was established at first. With image preprocessing, the location coordinates of each jujube target were obtained and these location coordinates were mapped into the spatial coordinate system. Combining judgment rules of the shortest path between frames, the location coordinates of targets were updated and transmitted with the video time sequences. Also, by using the method with video data, it could be quickly and efficiently to build data sets. Based on “Bagging” ensemblelearning and “returning” training method, the basic convolutional neural network tree models were built and then according to output of each basic tree model, the final result of the model was obtained by “voting”. The results of experiments showed that the location accuracy of 100% was achieved with this locating method, avoiding complicated mechanical and circuit design. At the same time, by using E-CNN model, the average recognition accuracy and recall rate reached 98.48% and 98.39%, respectively. And the classification accuracy was greater than those of color feature classification model (86.62%), texture feature classification model (86.40%), and basic convolution neural network model (95.82%). The model had high recognition accuracy and strong robustness, and can provide reference for other agricultural products sorting and detection.

Abstract:Currently in the industry, artificial broccoli cutting is used for the time being. The efficiency is low, and now mechanical device is needed to solve this problem. The broccoli cutting and throwing core mechanism was put forward. The working principle of broccoli cutting and throwing head mechanism was analyzed, the kinematic model was established, the computer aided optimization software was developed and a set of structural parameters was obtained to meet the trajectory requirements. The dynamics simulation of the mechanism was carried out. The simulation trajectory was basically consistent with the theoretical optimization trajectory. The mechanism motion was stable and there was no force overload phenomenon. The design of the physical prototype was completed and the highspeed photographic movement experiment was conducted. The prototype test results were basically consistent with the ideal trajectory, and the cutting tool was suitable for cutting broccoli in all sizes to meet export requirements, which verified the rationality of the design of broccoli cutting stem and throwing head mechanism. The cutting stem and throwing head tests were completed on the test bench, the success rate of cutting was 91%, success rate of throwing head was 100%, and the export requirements of broccoli small pieces on the market were met, which verified the feasibility of the broccoli cutting and throwing head mechanism.

Abstract:With the implementation of the “Thirteenth FiveYear” development plan of potato processing industry and the promotion of “main food” strategy of potato, the planting area of Chinese potato is getting larger and larger;the shape difference of potato or seed potato before potato planting is different for potato production. It has important influences, and it needs to be accurately screened by grading equipment to classify seed potatoes and potatoes of similar size for the same number of cuts;and quality grading of potatoes is also a necessary step before processing exports. However, most of the potato grading methods in China use traditional manual grading, which not only has high labor intensity, but also has low work efficiency. At present, potato grading machinery in China mostly uses the general equipment of fruit and vegetable products, and the grading equipment for potato is less, which can not meet demand for potato processing and export in China. Aiming at the problems of low grades and poor classification efficiency of the existing potato grading machines in China, a new roller potato grading machine was designed. The working principle of the machine was explained. The key components were designed by theoretical calculation, and the structural parameters of the grading device were determined. The force analysis of the potato movement process was carried out to determine the factors affecting the classification efficiency and classification accuracy of the potato grading machine. The potato grading machine was analyzed by Adams simulation software. The performance was simulated and the displacement curve of the potato was obtained, which was consistent with the structural theory. Taking the feeding amount of potato, the rotation speed of the roller and the lifting angle of the lifting device as the test factors, the bench test was carried out with the classification accuracy and classification efficiency of potato classifier. The test results showed that the potato feeding amount was 55t/h. When the roller advance speed was 120r/min and the lifting angle was 24°, the classification accuracy was 96%, and the extension efficiency was 53.7t/h, which met the operation requirements of potato grading machine. It provided a good foundation for the design and optimization of potato grading devices.

Abstract:The effect of pulsed strong light on sterilizing effect and quality of chilled chicken breast meat was studied. Combined with the principle of Box-Benhnken center combination design and response surface methodology, the sterilization conditions were optimized, and the quality of chilled chicken breast meat was evaluated. The results showed that pulsed strong light could effectively kill the surface microorganism of chilled chicken breast meat. The effects of pulse energy, pulse distance and pulse time on sterilizing rate of chilled chicken breast meat were significant, with the increase of pulse energy and pulse time, the bactericidal rate was increased, and the sterilization rate was decreased with the increase of pulse distance. With the increase of pulse energy and pulse time, the shear force was decreased, and the color difference was significant. With the increase of pulse distance, the shear force was increased obviously but it was less than 4kg, and there was significant difference in color difference. Under the optimized conditions of pulse energy of 400J, pulse distance of 12cm, pulse time of 50s, the sterilization rate of chilled chicken breast meat was 90.03%, and the shear force was 2.63kg. The loss rate of water was 30.31% and the color aberration was 3.53. Under these conditions, the relative errors of germicidal rate of colony total, centrifugal water loss rate, shear force and color aberration were obtained by verifying the results of the experiment. The relative errors were 1.07%, 1.17%, 1.54% and 2.02%, respectively. At the same time, the chilled chicken breast meat after pulsed strong light treatment was stored at 0~4℃, and the shelf life was prolonged for 1~2d, which could solve the practical problems faced by the factory.

Abstract:β-Carotene is used in food industry as a precursor of vitamin A with potent antioxidant activity through singlet oxygen quenching and deactivation of free radicals. Nevertheless, their utilization as nutraceutical ingredients in food industry is currently limited because of their poor watersolubility, high melting point, chemical instability and low bioavailability. Emulsionbased systems are often a better choice for delivering bioactive lipids such as β-carotene into functional foods since the emulsion increases bioavailability. The physical properties of β-carotene emulsions were characterized, which were stabilized by α-lactalbumin (α-LA) at different pH values with (-)-epigallocatechin-3-gallate (EGCG) as antioxidant. The particle size, zetapotential, encapsulation rate, stability index and interfacial protein of the emulsions were measured. EGCG addition had no effect on particle size, zetapotential and encapsulation rate of the emulsions, however, the addition of EGCG significantly influenced the physical stability of the emulsions. When the addition of EGCG was higher than 02% in the emulsions at pH value of 2.0, the physical stability was decreased with the increase of addition. The stability of emulsions at pH value of 7.0 was improved by the addition of EGCG in the range of 0.0025%~0.0200%, however, the stability of the emulsions was decreased when the EGCG addition was within 0.02%~0.10%. When the addition of EGCG was higher than 0.10%, the emulsions were separated into two phases quickly. In the mechanism study, the presence of EGCG changed the size and turbidity in α-LA solution when the addition was above 0.05%. Isothermal titration calorimetry (ITC) analysis implied that EGCG can interact with α-LA, with about five EGCG molecules integrated with one α-LA molecule. β-carotene emulsions destabilized by EGCG addition (greater than 0.10%) may due to the interaction between EGCG and α-LA.

Abstract:Anthocyanin in purple sweet potato is easy to degrade due to environmental factors during the storage, resulting in changes of purple sweet potato color and reduction of nutritional quality. The changes of anthocyanin in purple sweet potato during storage were analyzed by using nearinfrared spectroscopy, and rapid and nondestructive testing model was established. The near-infrared spectra of 120 purple sweet potato samples were collected at different storage times (0d, 2d, 4d, 6d, 8d, 10d, 12d, 14d, 16d, 18d, 22d and 30d). In the spectral region between 4000cm-1 and 10000cm-1, statistical mathematical models of anthocyanins in purple sweet potato were established with different preprocessing methods (Savitzky-Golay, first derivation and standard normal variate) using the partial least squares (PLS, SNV-PLS, iPLS and GA-PLS) methods. The results showed that standard normal variate (SNV) transformation was the best preprocessing approach. The iPLS and GA methods were used to select characteristic wavelengths, and the GA-PLS model was the best among the models developed, the R2v and root mean square error of validation values were 0.9136 and 7.2398mg/(100g)，the residual predictive deviation value was 3.3397. The optimal prediction model was verified, where the R2p and root mean square error were 0.8314 and 10.7663mg/(100g), respectively, and the residual sum was -10.0417mg/(100g). These results confirmed the feasibility of using near-infrared spectroscopy for the nondestructive detection of anthocyanin of purple sweet potato, which can provide a reliable method for intelligent screening of raw materials of purple sweet potato and quality monitoring during storage.

Abstract:In the research of the existing automatic parking system, the actual vehicle tracking constraints and initial pose conditions were ignored, which affected the actual vehicle tracking reference path effect. A path planning algorithm based on the B-spline theory and a non-time reference terminal sliding mode tracking control method based on approach law were proposed. Firstly, the motion process of vehicle was studied and the vehicle kinematics model was set up. Secondly, based on the B-spline theory, a nonlinear constraint single step parallel parking path optimization function was established, and vehicle kinematics constraints was analyzed. Then, based on non-time reference path tracking control and terminal sliding mode control method, a non-time reference terminal sliding mode tracking control method based on approach law was proposed. The nontime reference method was applied to avoid the influence of vehicle speed control and reduce the speed control requirement. Combining with the terminal sliding mode control method based on the reaching law, the controller controlled the vehicle tracking to the reference path, reduced the tracking error, improved the approach quality and reduced the buffing phenomenon. Finally, the path planning simulation was conducted for the initial position of the tilted parking, in order to verify the rationality of the path planning method. The effect of the design controller was verified by tracking the sinusoidal reference path on Simulink. And based on the Simulink and CarSim software, the rationality of the planning path and the control effect of the path tracking controller were verified.

Abstract:According to the requirements characteristics at different stages of generalized product design process and acceleration of the transformation from conceptual design to detailed design, a method of conceptual design push of 3D CAD model of products based on sketch was proposed. First of all, according to the conceptual design requirements, a three-view sketch was drawn by using a hand drawing board based on CAD geometric modeling platform. Then, feature information was extracted from hand-drawn three-view sketch and three-view projection diagram of CAD model projection in model library, and the 2.5D spherical harmonic descriptor was used to represent the sketch feature information. Finally, Euclidean distance was used to calculate the distance of the graph feature vectors obtained by spherical harmonic transformation to realize the similarity evaluation between models and verify the algorithm in the agricultural machinery equipment model database. The experimental results showed that the method can effectively help users visualize the query intention quickly, explore the 3D model which was most consistent with the intention of product conceptual design stage, and push the similar design resources to designers, so as to reference, inspire and expand the design thinking and realize the rapid response of product conceptual design.

Abstract:The four degrees of freedom（DOF）SCARA parallel mechanism（PM）is widely used in industrial manufacturing since it has three translations and one rotation (3T1R) pose positioning function. In general, this kind of PM features complex structures, high coupling degree, no inputoutput motion decoupling and singularity etc. Firstly, according to the topological design theory of PM based on the position and orientation characteristic (POC) equations and principle of avoiding singularity by using redundant actuation limb, a new and symmetrical 3T1R partially decoupled PM with low coupling degree κ and a redundant actuation was proposed. Then the topological characteristic analysis of the PM was performed, including POC set, DOF, coupling degree and motion decoupling performance. Afterward, according to the kinematics modeling principle based on ordered single opened chain (SOC), the solution model of direct kinematics was established, and the position solutions of the PM were solved by using onedimensional search method. Then, the workspace and rotational ability of the PM were analyzed based on the inverse position solutions derived. At the same time, the geometric conditions of three kinds of singular positions were also derived and the principle of avoiding the singular position using redundant driving chain was explained. Meanwhile, the velocity and acceleration curve of the base point of moving platform of PM was simulated based on the derived formula. The research result laid a theoretical foundation for the mechanical design, prototype implement and application of the manipulator.

Abstract:In order to improve the performance of differential pumps, a sixblade differential pump driven by denatured higher order ratio Fourier non-circular gear pairs was proposed. The denatured Fourier non-circular gear transmission model and the performance calculation model of the six blade differential pump were established, and the differential pump performance analysis software was compiled. The differential pump displacement, flow rate and pulsation rate were calculated at different order ratios and different denaturalization coefficients. The results showed that high order ratio was beneficial to improving the performance of sixblade differential pump, and the change of denaturation coefficient was beneficial to reducing the pulsation rate of single pump. The performance of the sixblade differential pump proposed was better than that driven by the ordinary Fourier noncircular gear pairs. In the same pump shell size and pipeline environment, the micro-strain of input shaft of the first impeller of single pump was reduced by 35.2%. It was indicated that the pulsation rate of differential pump would be decreased. The maximum modulus was increased by 27.7%, the displacement of the differential pump was reduced by 1.2%. The design was more conducive to low pulsation and large load conditions.

Abstract:Aiming at unbalanced radial force of hydraulic motor, the concept of couple hydraulic motor was proposed, which drove the rotor by a couple acting on the rotor, so that the rotor of the motor was subjected to the balanced radial pressure, the force condition of the rotating parts of the blade motor was improved and the service life of the motor was improved. The principle of three type’s couple hydraulic motor under different forms of action was elaborated. Based on the rotor radial force as the starting point, the relationship between number of blades and couple was analyzed in detail. Then it was got that even-acting hydraulic motor with even leaves and oddacting hydraulic motor with number of blades can be divisible by the motor actions can only be called the couple hydraulic motor. Finally, the radial force of the rotor was analyzed with the doublestator couple motor as an example. The mathematical model of the rotor radial force of the double-stator hydraulic motor in four different working modes was established, and the characteristics of the rotor radial force of the motor under four different working modes were analyzed. And the experimental platform was set up. The results showed that in four different working modes, the radial force acting on the rotor and the position of the action were periodically changed, and the radial force of the rotor was the smallest when the internal and external motor was differentially working. When the inner motor and the outer motor worked separately, the radial force was the second, and the radial force was the largest when the inner and outer motors worked together. Through the experiment of the prototype, the correctness of the principle of double-stator couple hydraulic motor and the rationality of the design of motor structure were verified, which laid a foundation for the future research and development of the double-stator couple hydraulic motor.

Abstract:In order to quickly and systematically identify the 12 geometric errors of the rotary axes of five-axis machine tool with a swiveling head, a five installation method for measuring and identifying geometric error based on the double ball bar (DBB) was proposed. Firstly, based on the distribution characteristics of the rotary axes of five-axis machine tool with swiveling head, the measurement models under the local coordinate systems of the rotary axes were established based on the multi-body system theory and the homogeneous coordinate transformation method, and the mapping relationship between the volume error vectors and the geometric error terms was established, which can also be used for geometric error compensation. Secondly, initial installation position and direction of the DBB were set, the continuous switching between different measurement modes was realized, and then the five installation method was proposed, which can realize the identification of the total 12 motion errors of the two rotary axes of five-axis machine tool with swiveling head, and it reduced the impact of installation errors on the accuracy of measurement and identification. Finally, the DBB-based motion errors measurement and identification experiments were carried out on the five-axis machine tool with swiveling head by using five installation methods. The geometric errors of five-axis machine tool with a turntable-tilting head were compensated with the identification values, and the average of motion errors of the two rotary axes were reduced by 48.89% and 51.49%, respectively. The accuracy and validity of five installation method were verified.

Abstract:To minimize the error between actual processing trajectory and theoretical trajectory in computer numerical control (CNC) machine tool, an error optimization method with the redundant feature of six-axis linkage CNC machine tool was proposed. Firstly, the kinematic model of a type six-axis linkage CNC machine tool which had three linkage axes and three rotation linkage axes was established. Then, the feature of redundant linkage of machine tool was researched, and the redundant rotation linkage axis was defined. With the trajectory model of contact point between tool and workpiece, the trajectory errors models of tool center point and axis vector were established. The errors models showed that the values of them depended on the motion of rotation linkage axes. The motion of redundant rotation linkage axis was applied to adjust the motions of all linkage axes. The values of the two errors became the minimum when the sum of the motion of rotation linkage axes became the minimum. And, it made the values of the processing trajectory error became the minimum at the same time. To demonstrate the validity of the optimization method, two polishing experiments were made in a six-axis linkage CNC machine tool. An experiment was made in the five-axis linkage mode that the redundant rotation linkage axis was motionless, and another experiment was made in the six-axis linkage mode. Because the lower machining trajectory error made the lower surface roughness and the higher of its consistency, compared with the five-axis linkage mode, the processing result in six-axis linkage mode was more excellent. The validity of the method was verified by the results of experiments.

Abstract:Experimental and calculating analysis of magnetic losses for giant magnetostrictive materials is necessary steps for the design of high power magnetostrictive transducer. In order to further research the magnetic energy losses characteristics, a Terfenol-D rod was sectioned along different directions, and these slices were made into several square annular sheet samples. The influences of magnetization direction and dimension parameter on the magnetic losses were compared and analyzed. Under different frequency and magnetic density of driving magnetic field, the magnetic energy losses were measured to analyze the variation trends of the losses. Based on the loss separation formula and measured data, the effects of eddy current skin effect and dynamic hysteresis characteristics were taken into consideration. The variation trends of the losses coefficients were investigated with numerical simulation. The results showed that the high frequency magnetic energy losses for Terfenol-D were increased rapidly in both value and growth rate with the increase of frequency and magnetic density. When the frequency was 5kHz, the losses were increased from 2.742W/kg to 153.890W/kg as the flux density was varied from 0.01T to 0.09T. The losses were increased by 55.12 times. When the flux density was 0.05T, the losses were increased from 8.138W/kg to 319.428W/kg as the frequency was increased from 1kHz to 20kHz. The losses were increased by 38.25 times. The losses coefficients varied with high frequency and magnetic density. When the frequency was above 5kHz and the magnetic density was higher than 0.05T,the average error of the model between the calculated value and the measured value was 3%. The numerical model was suitable for calculating high magnetic energy losses of Terfenol-D. It can provide a theoretical and experimental guidance for the high frequency applications of magnetostrictive materials.