Abstract:The potato planting in China has the characteristics of large area, wide range and complicated geographical features. The mechanized potato planting is the most important technical link in the mechanized potato production, which has prominent problems in potato growing industry. The technology of the mechanization of potato planting includes key technologies of seed potato pretreatment, seed supply and conduction, seed pick and seed clearance. This paper analyzes the present situation, characteristics and restrictive factors of the mechanization of potato planting in China, summarizes the key technologies of the mechanization of potato planting, and the restriction, influence and difference between the two main cultivation methods of whole potato and diced seed potato planting technology in Mechanized potato planting. The research emphatically expounds the status and the development trends of potato grading, seed potato separation, zerospeed seeding, dynamic seedsupplying technology and equipment, and summarizes the representative potatogrowing machinery in China, Germany, the Netherlands, Belgium, the United States and other countries. Besides, the paper holds that the precise, highspeed and intelligent largescale potato seeding technology and equipment are the core direction of the development of the technology of mechanized potato seeding in China, which will provide reference for the industry in equipment selection, research and development and the development of potato planting machinery in China.

Abstract:In order to meet the development demands of modern agricultural machinery automatic operation, the rice transplanter automatic operation system was designed to realize the automatic control of transplanting operation and driving speed. Taking the Iseki PZ-60 rice transplanter as the research platform, the automaticmanual integration control scheme with manual mode priority was designed for transplanting components and driving speed based on the controller area network (CAN) communication. Accordingly, the incremental proportional，integral and differential (PID) as well as expert PID algorithm were designed respectively aiming at the speed and transplanting control. Meanwhile, the combined control strategy for the autooperating transplanter was developed. Afterwards, the speed control effect of the proposed navigation control system was tested on the cement road and two kinds of paddy field each with flat bottom layer and uneven bottom layer respectively. The results showed that the average errors of speed control were 3.25%, 5.40% and 8.01%, respectively, the probability of the speed errors which was within 10% were 98.6%, 90.1% and 68.0%, respectively. A kind of paddy field with flat bottom layer was selected to conduct the combined control experiments. The results showed that the automatic combined operation control of the transplanter had approximately the same effect with that operated manually. The results indicated that the developed automatic operation system of the transplanter can meet the automatic operation requirements of the unmanned transplanter.

Abstract:The soil in the middle and lower reaches of the Yangtze River is sticky and hard. The quality of traditional straw returning tillage machine is not ideal, and the knife roller is easy to be twisted and the power consumption is large. To solve the above problems, a sixhead spiral straw returning cultivator’s knife roller was proposed. Secondary cutter blade was designed, and the structure of knife roller and working principle were illustrated. The reduction degree of the secondary cutter blade and the major working parameters were analyzed. The results of experiment showed that the influence of factors on power consumption and straw burial were significant, which from large to small were rotating speed of knife roller, tillage depth, working speed and tillage depth, working speed and rotating speed of knife roller, respectively. The influence of factors on straw crushing and soil pulverization were significant, which from large to small were rotating speed of knife roller, working speed and tillage depth. The optimum value of tillage depth, working speed and rotating speed of knife roller were 12.7cm, 0.7m/s and 273r/min, respectively. The results of verification experiment showed that the power consumption, rate of straw burial, rate of straw crushing and soil pulverization were 31.9kW, 93.1%, 87.5% and 78.3% when working on the optimum values. The errors between the predicted values were 4.7%, 1.4%, 1.3% and 5.8%, respectively. The results of contrast experiment showed that the power consumption and the rate of straw burial of six-head spiral straw returning cultivator were 8.8% and 2.3% lower than that of cultivator for straw returning in paddy field and dry land, respectively. However, the rate of straw crushing and soil pulverization were 3.0% and 6.1% higher than that of the latter. The research results can provide reference for the design and improvement of straw returning tillage machine in the middle and lower reaches of the Yangtze River.

Abstract:Aiming at the problems of large cutting resistance and high energy consumption when working on rotating monomer of traditional cultivators, the key component of rotary cultivator was designed according to the method of vibration reducing resistance in agricultural machinery design. The motion equation of rotating monomer was established, and the analysis of reducing resistance was done. The analysis can provide theoretical basis for the design of the rotating monomer. For the study on performance of rotary cultivator, the quadratic regression orthogonal rotation combined design was used for the experiment. The forward speed, spring stiffness coefficient and rotational speed of knife were taken as the influential factors, the rate of broken soil and the power consumption were taken as test indexs, and the test was conducted in the indoor soil bin. Through the variance analysis and response surface analysis by DesignExpert software, the mathematical model between influencing factors and response indexes was obtained, and the mathematical model was optimized and validated. The field test showed that when rotational speed of knife was 247~268r/min, forward speed was 0.5~1.0m/s and the spring stiffness coefficient was 11.39~15.16N/mm, the rate of broken soil was 91.3%~92.9%, the power consumption was 1.55~1.90kW, the result of contrast test showed that the vibration can effectively reduce the operating power consumption of the rotating monomer, compared with the traditional device, the results showed that the vibration rotating monomer can reduce the power consumption by 32%. To the optimal level combination of field experiment, the rate of broken soil was 92.8%, and the power consumption was 1.95kW. The results showed that the vibrating rotary monomer can meet the requirements of operation technology of cultivator. The research result provided important theoretical and technical reference for the improvement and optimization of the key components of rotary cultivator.

Abstract:Existing agronomy of American ginseng cultivated in China, which uses narrow row spacing and precision seeding, has persistent challenges that employ a seeder to improve efficiency and guarantee precision, highlighting a need for narrow row spacing precision sowing technology and equipment. The object was to explore an innovated prototype of multi narrow rows parallel tubeneedle centralized seeding device to address the challenge, which combined positive and negative air pressure to suck and discharge the seed respectively. The working principle of the prototype device was introduced and main structural parameters were confirmed. The uniformity of airflow field distribution between rows of the prototype device was estimated by employing the simulation analysis. The mechanical model for seed sucking and discharging during the seeding process was constructed. Finally, the seeding performance of the prototype device was tested by bench test and the influence law of the seeding performance was investigated. The result of airflow field simulation analysis showed that the coefficient of variation on the airflow average velocity value of each seeding needle at the end adsorption surface was 2.923%, which proved that the airflow field of the centralized seeding device designed was evenly distributed. The bench test results showed that the seeding qualified index of the prototype device reached more than 90%. Combined with the quadratic regression rotation orthogonal combination test and response surface analysis, it was showed that the primary and secondary factors affecting seeding qualified index and missing index were rotating speed of the seed meter shaft, the negative pressure and the positive pressure successively. The optimal working parameters combination was optimized as the row axis speed of 13.10~17.70r/min, the negative pressure of 4.25~4.50kPa, and the positive pressure of 2.90kPa. Within the optimal condition range, the qualified index of a single row was greater than 88.50%, the missing index was less than 5.00% and the multiple index was less than 7.50%. The difference working conditions in the optimal condition range were selected to estimate the overall performance of the prototype device. The result showed that each row qualified index of centralized seeding device was greater than 8630%, the consistency coefficient of variation for each row was less than 1.80% and the stability coefficient of variation for each row was less than 6.20%, which confirmed that the seed metering device worked stably and achieved the precision seed metering requirements for American ginseng sowing. The research result provided the core device for further developing American ginseng seeder adapted to the precision planting agronomic requirements.

Abstract:In the process of structure design of drum-type no-till planter mechanism, many parameters are involved, interaction is complicated, calculation is large, calculation method is tedious, design period is long, and the optimization design of mechanism is not easy to complete. An interactive design platform was studied. Through man-machine interaction, the design cycle was shortened and the mechanism was optimized. Based on the kinematics analysis of the core mechanism composed of duckbill drum seeding device and drum driven by its duckbill, the mathematical models of the driving angle, aiding angle, angular velocity and the angular velocity of roller were established. With plant spacing, return amount and sowing depth as design parameters, objective function and constraint conditions were constructed, optimization algorithm was determined, and structural parameters which met the design requirements were obtained, including the basic structural parameters of roller radius, drum radius, duckbill height and duckbill number, and auxiliary structural parameters of the booster angle, driving angle, number of holes and length of hole. According to the optimization algorithm, the program was written by using Matlab, and the optimized structure parameters were obtained directly through the Matlab graphical user interface. Through the secondary development under the environment of CATIA, the parameterized model was established by using the association design method, and the optimized structural parameters were used to drive the model. According to the structural parameters obtained from the system, the structure test prototype of the drumtype notill planter mechanism was processed and the functional test of the prototype was carried out. The interactive optimal design system can quickly generate various structural parameters under different requirements, get the optimal parameter combination accurately, generate the required model, shorten the designer’s design time to the maximum extent, and improve the design efficiency and accuracy. At the same time, it provided a general method for the study of this kind of problems.

Abstract:Aiming at the problems of complicated folding and unfolding process, poor synchronous coordination and the obvious mechanical vibration of traditional mechanical spray rod, a spraying rod consisted of single cylinder multiple folding mechanism was designed combined with the agronomic characteristics of paddy field plant protection in Northeast China. The structure and working principle of the spraying rod with multiple folding mechanism were expounded and analyzed. The length of each part was determined according to analytic method. Through orthogonal experiment and virtual simulation technology, the effects of various types of steel pipes with different wall thicknesses on spray rod quality and firstorder natural frequency were investigated, and the results were analyzed and optimized by DesignExpert 8.0.6 software. The optimization results showed that when the wall thickness of round steel pipe, rectangular steel pipe and square steel pipe was 2mm, 2mm and 2mm respectively, the mass was 62.85kg, which was the lightest and the dynamic characteristic was good at this point. Its first order natural frequency was 14.84Hz, which avoided the 13.03Hz of the pavement incentive frequency. The finite element model of the sprayer was established by ANSYS-workbench software and the numerical modal analysis was carried out. The first four order nonzero modal frequency and vibration mode of the sprayer were solved, and the accuracy of the numerical model optimization results was verified by modal test. Field experiments showed a stable performance of the machine, uniform spraying of liquid pesticide solution, good coverage, and no obvious vibration of spraying lever during operation.

Abstract:An agricultural vertical takeoff and landing (VTOL) tailsitter UAV with symmetrical winglets and wings was designed. The main parameters of the taisitter, wingspan, wing root, wing slightly, sweep angle, winglet slightly, winglet slightly longer, winglet height, winglet sweep angle, winglet thickness and winglet length were investigated to study the relationship between the structural parameters and the endurance time. The 3D model of tailsitter and its outflow field were established with CATIA and ANSYS software. The outflow field of tailsitter was simulated by using computational fluid dynamics (CFD) software with model under 130 different structural parameter combinations. The feature factors of aerodynamic coefficients and weight coefficients were screened with the analysis of variance. Relationship between characteristic structural parameters and endurance time was established with the accuracy of 0.97. Four models of aircraft were processed by 3D printing technology for wind tunnel test. The aerodynamic coefficients of the aircrafts in cruise state were measured. The relative error between aerodynamic coefficient numerical simulation and wind tunnel test results was less than 14%. Simulation results were verified by measuring the endurance time in the fixedpoint hover of the two produced UAV samples. The result showed that the relative error was less than 15%, and the model can be used to optimize the design of structural parameters for the agricultural VTOL tailsitter UAV.

Abstract:In order to solve the unmatched problem between airflow field generated by traditional cylindrical fan of vibrating screening transverse axial flow combined harvester and the distribution of separated mixture on the screen surface, a conical centrifugal cleaning fan was designed and its working principle was described, which can improve the quality of cleaning by optimization of cross wind. According to the actual structure, a threedimensional model of the cleaning device was established and a numerical simulation of the flow field distribution of cleaning room under the action of cylindrical cleaning fan and conical cleaning fan with different taper blades was conducted by using the CFDesign software. The results showed that the transverse wind was obviously produced by the conical cleaning fan along with the direction of screen width. The speed of transverse wind was increased with the increase of taper value of the fan blade, but the speed of longitudinal wind along the length of the vibrating screen was decreased with the taper value of the fan blade. The area of low wind speed zone at middle position of the vibrating screen also became larger, which was detrimental to the cleaning of mixture. The best velocity distribution of the cleaning room was appeared when the taper value of the fan blade was 3.5°. The experiment of the flow field under different types of cleaning fans was conducted by using the distributingpoint method. The results showed that the speed of transverse wind at the corner of the entrance of the vibrating screen can reach 2.68m/s, and the speed of transverse wind at middle position of vibrating screen can reach 2.07m/s, which was obviously bigger than the value produced by the cylindrical cleaning fan and beneficial to the distribution of the separated mixture along with the screen width. At the end of the screen length, the speed of the longitudinal wind produced by the conical cleaning fan was 0.78m/s, which was smaller than the longitudinal speed and helped to reduce the loss of grain cleaning. The distribution experiment was also conducted for the action of cylindrical cleaning fan and the conical cleaning fan. The results showed that the weight of mixture in main falling area made up 59.21% of the weight of all mixture under the action of conical fan and the number of cylindrical fan was 69.74%. The offset location where the maximum weight mixture appeared under the action of conical fan was adjusted to 166mm along the width direction compared with cylindrical fan, and the weight dropped by about 27.66%. It was verified that the conical fan can apply the transverse wind to blow away the mixture gathered in the inlet of the vibrating screen, which was conducive to improve the cleaning quality. Field experiment was conducted and the results showed that the performance indexes of combine harvester furnished with conical fan, including loss rate, impurity rate and crushing rate were obviously better than those stipulated in occupation standards. It can reduce the impurity rate index of combine harvester obviously, contrasting the conical fan with cylindrical fan.

Abstract:Corn has become the top substitute for rice and wheat, thereby significantly influencing the lives of people involved in increasing corn production. The technology of corn harvesting has been developing toward the direction of mechanical harvesting. At present, corn grain harvesting can complete harvesting, threshing and cleaning process at one time, which reduces operation process and improves working efficiency. It is the development trend of corn harvest. However, the corn grain moisture content restricts the development of corn grain harvest. In order to solve the problem of high maize kernel damaged rate and high unthreshed rate during the corn harvest in Huang-Huai-Hai region, a transverse axial flow corn threshing test system was designed which used flexible tooth and elastic short rasp bar as threshing elements. In order to make the material in the cylinder have a transmission capacity, the flexible tooth and elastic short rasp bar were arranged in four heads. The test system adopted grid concave. Six spiral guide bars were arranged at the inner wall of the cover to assist the speed of material movement. The key design parameters of this type threshing system were calculated and explained. For the sake of reliability, the dynamic balance simulation was carried out with ADAMS software and YYW-1000 dynamic balance machine checked the accuracy. The threshing cylinder speed, concave clearance and feed rate were selected as the influence factors, and the maize kernel damaged rate and unthreshed rate were selected as the performance indexes in the orthogonal experiments. The optimal experimental results were as follows: threshing cylinder speed was 450r/min, the concave clearance was 40mm and the feed rate was 8kg/s. And the corresponding performance indexes were as follows: the maize kernel damaged rate was 0.65%, the unthreshed rate was 0.59%, which could completely reach the requirement of the national standards in China. The research result of the threshing system provided reference for design of the type of corn harvester.

Abstract:Cottonstalk is an important renewable resource. With an annual output of 31.5 million tons, China is rich in cottonstalk, which has great potential economic benefits. Cottonstalk uprooting is laborintensive and rollertype uprooter is not suitable for cotton planting patterns in China. Dentate disc cottonstalk uprooting device has good application prospect. Relevant research focused on cottonstalk mechanical properties, uprooting force and uprooting device design, but lack of further research on cottonstalk movement analysis and uprooting mechanism. It is urgent to carry out a deeper research on the technology and machinery of cottonstalk uprooting. In order to solve the problem of omission, fracture and low pulling out rate of the cottonstalk uprooting machine, a dentate disc multirow cottonstalk uprooting device was designed based on the electrohydraulic control technology and corresponding tests were taken. ADAMS was used to simulate the movement of the device and further reveal the cottonstalk uprooting mechanism. Under two operation modes of the device (speed locking mode or speed ratio locking mode), univariate analysis and multivariate regression analysis method were used to investigate the influence of dentate disc circumference speed, tractor forward speed and speed ratio (dentate disc circumference speed by tractor forward speed) on the omission, fracture and low pulling out rate of cottonstalk. The results showed that the device could meet the design requirements which can carry out cottonstalk uprooting test under various conditions. The magnitude, direction and duration of the uprooting force could affect the uprooting results. When the clamping time was less than the uprooting time, it would easily cause cottonstalk fracturing. Increasing the dentate disc circumference speed would contribute to a low omission rate. Speed ratio and dentate disc circumference speed both had significant impact on the pulling out rate, omission rate and fracture rate of cottonstalk. The speed ratio was the most critical factor which determined the pulling out rate of cottonstalk. The optimal speed ratio range was from 0.55 to 0.80, and the optimal dentate disc circumference speed range was from 0.24m/s to 1.10m/s. When the dentate disc angle was 6°, the tractor forward speed was 0.85m/s, and the speed ratio was 0.75, the pulling out rate of cottonstalk reached its maximum value of 93.89%, the fracture rate was 4.43% and the omission rate was 1.68%. The research result could provide a theoretical basis for optimizing structure and performance of cottonstalk uprooting machine.

Abstract:As manual rubber tapping is a laborintensive work with high technical requirement and low work efficiency, it is important to realize automatic rubber tapping. A threecoordinate linkage rubber tapping device was designed and tested, and a motion path planning method based on short tapping cut was proposed. The tapping device was composed of three main modules, which were threecoordinate platform (positioning accuracy of single axis was ±0.05mm), a vibrating cutter and a laser ranging sensor (measurement accuracy was 0.07mm). In order to control cutting depth, laser ranging was used to measure the distance between the knifepoint of vibrating cutter and the reference surface curved by skilled tapper. Based on the measurement, a spatial path was planned for threecoordinate platform simultaneously. During rubber tapping, vibrating knife cut off the bark of rubber tree continuously through the path by controlling threecoordinate platform. Therefore, the motion path planning method of the tapping device could be summarized as: detecting the start point and inclination of short tapping cut through a rectangle motion path; measuring the cutting depth through a discrete motion path; planning cutting path fused the information of tapping cut and cutting depth. Furthermore, the number of control points to approximate the short tapping cut was optimized. In the Xdirection of the tapping motion coordinate system, the length of short tapping cut was intercepted as 80mm, and the reasonable number of control points was calculated as 17. Moreover, the tapping device was tested on real rubber tree trunk, and the working performance was evaluated by measuring cutting depth and bark consumption. Test results showed that the cutting depth was well controlled with no damage on rubber tree and the error of bark consumption was about 5%, which could meet the requirements of natural rubber tapping requirement.

Abstract:The objective was to improve the quality and effect of shell breaking on pecan after the firsttime breaking. In order to make up for the shortage of the first shell breaking of pecan and ensure the more effective separation of shell and walnut kernel, a secondary shell breaking method based on centrifugal force impact was proposed for pecan with unsatisfactory shell breaking effect, and a secondary shell breaking machine based on centrifugal force was developed. According to the material characteristics of pecan and various mechanical characteristic parameters required for shell breaking, a mathematical model for the design of the secondary shell breaking mechanism was established, and key structural components such as feeding and shell breaking mechanisms were designed in detail, the key parameters were determined, the whole machine model was established, and the sample machine trial production was completed. The experiment of the sample machine showed that when the water content of pecan was 14.55%~16.35%, and the diameter was 18~22mm (along the seam line direction), the speed of the centrifugal rotating device was 410r/min, the distance between the edge of centrifugal rotating device and the collision wall of conical cylinder was 80mm, and the feeding speed was 200g/s，the effective rate of breakage was larger than 87.85%, the rate of damage to walnut kernel was less than 16.14% and the rate of production exceeded 500kg/h. The accuracy and stability of each sample machine were verified, which met the actual requirements of the current pecan processing industry.

Abstract:In order to improve the classification accuracy of hyperspectral remote sensing images, a novel hyperspectral image classification algorithm based on local preserving reduced dimensional convolutional neural network (DCNN) was proposed by using local preserving discriminant analysis and deep convolutional neural network (DCNN) algorithm. Firstly, the dimensionality reduction of hyperspectral data was analyzed by local reserved discriminant, and then the spatial tunnel information was filtered by twodimensional Gabor filter. Secondly, the original hyperspectral data were extracted by convolution neural network to generate spectral tunnel information. Thirdly, the spatial tunnel information and spectral tunnel information were integrated to form the airspectrum characteristic information, which was input into deep convolutional neural network to extract more effective features. Finally, the feature of the final extraction was classified by using the dual optimization classifier. The proposed method was compared with CNN, PCA-SVM, CD-CNN and CNN-PPF in the performance of Indian Pines and University of Pavia hyperspectral remote sensing databases. In the database of Indian Pines and University of Pavia, the overall recognition accuracy of the proposed method was 3.81 percentage points and 6.62 percentage points higher than that of the traditional CNN method. Experimental results on two databases showed that the proposed method was superior to the other four methods in both classification accuracy and Kappa coefficient, and it was a better classification method for hyperspectral remote sensing data classification.

Abstract:The ear of winter wheat, as an important agronomic component, is not only closely associated with yield, but also plays an important role in phenotypic analysis. It was reported that the number of winter wheat ears per unit area was one of the commonly used indicators to indicate the winter wheat yield. However, the traditional manual counting method is timeconsuming and laborintensive, as well as subjective, lacking a unified winter wheat ear counting standard. In order to increase the accuracy of winter wheat ear recognition and detection in field condition, a winter wheat ear detection system was constructed based on image processing and deep learning. Firstly, a winter wheat ear recognition model was proposed, which was based on manual image segmentation and convolutional neural network classification. A 27layer network with five convolutional layers, four pooling layers and two fully connected layers was constructed. The gradient descending method (SGD) was used to train and validate the model by setting the maximum number of epochs at 200. The network was trained with an initial learning rate of 0001. In the winter wheat ear detection and counting stage, a nonmaximal suppression (NMS) method was used to overcome the effect of overlapping results by using a confidence score. The confidence score p was set to be 0.95, and the I threshold was set to be 0.1. The results showed that the system achieved an overall recognition accuracy of 99.6%, 99.9% for winter wheat ear, 99.7% for shadow and 99.3% for leaf, which indicated that the winter wheat ear detection system was capable of recognizing winter wheat ears. The linear regression was used to test the accuracy of the counting results. Normalized root mean squared error (NRMSE) and coefficient of determination (R2) were used as the criterion for evaluation. The comparison between the counting results by the system of the selected 100 photos and the manual counting results showed that R2 was 0.62 and NRMSE was 11.73%. It was revealed that the accuracy of winter wheat ears could be achieved by the system, which can provide support to yield estimation and field management of winter wheat.

Abstract:In order to detect underwater crabs, a detection method based on machine vision was proposed, which can produce necessary feedback data on the number and distribution of crabs to automatic bait casting boat in real time so that the boat can cast baits precisely. An underwater camera with LED light installed at the bottom of the boat was used to capture images of crabs. These images taken under water were enhanced by optimized retinex filter firstly, which can make images clearer and enhance the details in images. Then, a dataset included original images captured underwater, captured from a laboratory and downloaded from webs was built. There were totally 3500 labelled original images in the dataset. The dataset was augmented and divided into training and test datasets. Finally, a deep convolution neural network, YOLO V3 was trained to detect the crabs by training dataset. The mean average precision of trained network reached 86.42% on test dataset, the detection precision for underwater crabs was 96.65% and the recall ratio was 91.30%. Compared with crabs with big size, the crabs with small size were more difficult to be detected. Compared with other methods for object detection, YOLO V3 can reach a high level of both recognition precision and speed. The recognition speed of the proposed method was 10.67f/s, which was higher than that of other methods on the same hardware platform. Therefore, the proposed method was real time and had application values.

Abstract:With the rapid development of detection technology, a variety of pH value detection methods was invented. However, there were many pH value detection techniques, but few of them can be used in field. Thus a soil pH value online realtime detection system in this situation was designed. It was found that the measurement of pH value sensor was greatly influenced by soil moisture and temperature. In order to reduce the influence of soil moisture and temperature on soil pH value measurement, a model of moisture and temperature compensation for pH value sensor was proposed. Soil pH value measurement values were linearly analyzed by the least square method with soil moisture and temperature. The results showed that the absolute error of pH value measurement caused by temperature and soil moisture was reduced by more than 84.5%, and the variation range of pH value measurement was not more than ±0.1. Compared with ZD-18 soil acidity meter, HYSWR-ARC-12V soil moisture sensor and mercury thermometer, three determinant coefficients were all above 0.99. It proved that the performance of the system was equivalent to mature products. In order to ensure the applicability of soil pH value measurement in natural environment, it was explored that the threshold of soil moisture for pH value sensor was effectively measured, which proved that the pH value sensor can be effectively used when the soil volume moisture was more than 5%. Experiments showed that the pH value sensor can be effectively measured in the range of 3.06~10.36, and the detection error was -1.53%~3.51%. The design of a highaccuracy soil pH value online realtime detection system was realized.

Abstract:In order to estimate the nitrogen content of sugar beet leaves quickly, sugar beet was taken as the research object. The hyperspectral image data of canopy leaves was obtained by hyperspectral imaging spectrometer. At the same time, the nitrogen content of leaves was determined by Kjeldahl method. Based on the meticulous sampling method, the normalized spectral parameter (NDSI) and the soiladjusted vegetation index (SASI) were constructed in the wholewavelength range. Moreover, in order to search for the optimal value of L in SASI under arbitrary band combination，the particle swarm optimization algorithm was proposed to optimize the L. On the basis of the previous work mentioned above, the sensitive spectral parameters were selected to achieve the optimization, and the estimation model was constructed to carry out the quantitative diagnosis and visualization research of the nitrogen content in the sugar beet leaves. The results indicated that the sensitivity of SASI to the canopy leaf nitrogen content (CLNC) of sugar beet was higher than that of NDSI for each different growth period. Especially in the nearinfrared region where saturation easilyoccurred, the correlation was significantly improved. Compared with the conventional spectral parameters, based on SASI1(R430.20, R896.76) and SASI2(R433.03, R896.01), an optimal CLNC estimation model of BP net for the rapid growth period of the beet leaves was able to be established. The determination coefficient (R2) of validation set was 0.78, the root mean square error (RMSE) was 2.48g/kg and the relative error (RE) was 4.18% (in the year of 2015). The model established based on SASI3(R952.09, R946.11) and SASI4(R760.37, R803.48) for the sugar growth period had the best performance. The R2 of verification set was 0.67, the RMSE was 2.71g/kg, and RE was 4.72% (in the year of 2015). The optimal modeling parameters for the sugar accumulation period were SASI5 (R883.30， R887.79), and the R2 of the model was 0.72, the RMSE was 2.54g/kg, and the RE was 4.49% (in the year of 2015). Based on the above model, combined with the spectral information of each band under every pixel of hyperspectral image, the CLNC was calculated, and the CLNC concentration graphs of sugar beet were plotted, which directly and visually presented the distribution of nitrogen content in the sugar beet leaves at different time scales and different leaf positions. The research results introduced that the proposed estimation method of CLNC in sugar beet was feasible, which also provided technical support for timely observation of crop growth and nutritional diagnosis.

Abstract:Aiming at the problem of irregularity of the pest area in the aerial images taken over forest area (discussed as forestry pest images in the following) and the poor generalization ability of traditional recognition method, a method for pest image segmentation based on full convolution network was proposed to realize automatic recognition of pest area. Firstly, the insect image of the forest area was needed to be obtained by using the eightrotor UAV aerial photograph technique over the pest forest area, and the pest area was marked with pixels for model training. Secondly, the full connection layer of the VGG16 model was replaced with the convolutional layer, and an endtoend study was used by implementing up sampling; and then the pretraining convolutional layer parameters were employed to improve the convergence speed of the model; finally, the skip layer was used to fuse a variety of feature information, which effectively improved the recognition accuracy, and five convolutional networks was constructed by this method. Experiment results showed that FCN-2s had the highest recognition accuracy among the five fullconvolution networks for forestry pest images. The pixel accuracy of the segmentation results was 97.86%, the mean crossover ratio was 79.49%, and the segmentation time for single image was 4.31s. Compared with Kmeans, pulse coupled neural network and composite gradient watershed algorithm, its pixel accuracy was higher by 44.93, 20.73 and 6.04 percentage points, respectively, the mean intersection over union towered above 50.19, 35.67 and 18.86 percentage points, and its segmentation time for single image was reduced by 47.54s, 19.70s and 11.39s, respectively. This method can realize the rapid and accurate recognition of pest area in aerial forest areas, which provide a basis for pest detection and prevention in forest areas.

Abstract:Traditional methods of obtaining potassium content of citrus leaves are timeconsuming procedures with complex operations which can be harmful to citrus trees. Moreover, traditional methods cannot meet the demand for rapid and nondestructive monitoring of potassium content in largescale citrus orchards. Combined with the stateoftheart deep learning technology, a model based on stacked sparse autoencoder (SSAE) and deep learning networks (DLNs) using hyperspectral information for potassium content prediction in four growth stages was proposed. The experiments were conducted in the Crab Village of Luogang District, Guangzhou City, Guangdong Province, and the samples were 109 citrus trees planted. During four growth stages, i.e., germination, stability, bloom and picking stages, hyperspectral reflectance of citrus leaves was respectively measured by spectrometer (ASD FieldSpec 3), and at the same time, potassium content of citrus leaves was obtained by using traditional chemical method. All the collected samples constituted a largescale dataset with totally 436 tuples, 80% of which were utilized as the calibration set and remaining 20% as the validation set. The constructed model which relied on the calibration set and the validation set was evaluated respectively. Firstly, successive projection algorithm (SPA) was provided to deal with the highdimensional spectral vectors for dimension reduction and feature extraction. A prediction model of multiple linear regression (MLR) for potassium content of citrus leaves was established based on those extracted features. The result showed that the potassium spectrum contained a large number of complex nonlinear characteristics. Secondly, wavelet denoising was applied to reduce the highfrequency noise in the original spectrum, and the optimized parameter combination of wavelet denoising through orthogonal test was as follows: “coif2” as wavelet basis function, the number of decomposition layer was 3, “sqtwolog” as the threshold, and “one” as noise estimation scheme, respectively. Thirdly, the features of SSAE in a specific stage were transferred and merged into baseline layer by layer to find out the best number of layers. The result showed that the best numbers of transferred layer were 3, 1, 4 and 3, and the corresponding values of determination coefficients for calibration set were 0.8999, 0.8598, 0.8869 and 0.8547 at germination, stability, bloom and picking stages, respectively, which were improved by 19.82%, 9.45%, 21.49% and 7.21%, respectively, compared with baseline. Then, the features of SSAE in the best layer were transferred and merged into baseline stage by stage to find out the best number of transferred stage. The experiment revealed that features of all four stages were transferred to its corresponding stage domain achieving the best performance. In this situation, the coefficients of determination for calibration set were 0.877 2, 0.8981, 0.9049 and 0.8894 at germination, stability, bloom and picking stages, respectively, which were improved by 16.80%, 14.32%, 23.96% and 11.56%, respectively, compared with baseline. Fourthly, after performing wavelet denoising and four kinds of spectrum transformation, i.e., the first derivative, second derivative, reciprocal and logarithm to the original spectrum, the layers’ features and stages’ features, which were obtained in SSAE previously, were transferred and merged into spectrum in four growth stages. When the first derivative spectrum was used as the input vector of the samples with wavelet denoising, the SSAE-DLNs model achieved the best result and the coefficients of determination for calibration set were 0.8992, 0.8899, 0.8838, 0.8727 and 0.8988, respectively, and the corresponding values of RMSE were 0.5425, 0.5496, 0.5509, 0.5539 and 0.5443, respectively, and the corresponding values of sparse proportion were 0.1411, 0.1633, 0.1189, 0.1856 and 0.2078, respectively, at germination, stability, bloom, picking stages and the whole growth period; and for the validation set, the coefficients of determination were 0.8651, 0.8704, 0.8551, 0.8580 and 0.8771, respectively, and the corresponding values of RMSE were 0.5693, 0.5674, 0.5786, 0.5722 and 0.5528, respectively. Comparing with traditional models such as support vector regression (SVR), partial least square regression (PLSR), general regression neural networks (GRNN) and stepwise multiple linear regression (SMLR), SSAE-DLNs model achieved the best performance, and the next was SVR, in which R2 of calibration and validation set were 0.8988 and 0.8771, respectively. Finally, the research result proved the feasibility of monitoring potassium content of citrus leaves, which may provide a theoretical basis for growth monitoring and nutritional diagnosis of citrus trees. 

Abstract:Baotou City of Inner Mongolia was selected as the study area. The Landsat OLI image of Baotou City in summer of 2016 was selected as the research data for interpretation. Totally 28009 grassland landscape patches were extracted. The normalized difference vegetation index (NDVI) was calculated from the original image. According to the NDVI of the study area, the grassland landscape was divided into 12 levels. Based on 12 levels of grassland landscape, a network of grassland landscapes was constructed. At the landscape level, totally 25 indices were selected, and at the type level, 24 indices were selected. Using these indices, the spatial pattern, shape characteristics and degree of aggregation of the grassland landscape were analyzed. The results showed that the landscape similarity percentage index and the distribution and the sidebyside index were higher on the landscape scale, and the landscape segmentation index was lower in the whole territory of Baotou City. The proportion of grades 1~7 was high, the density of landscape patches was low, and the aggregation index was high. The proportion of grades 8~12 was low, the landscape segmentation index was high, the landscape was broken and the connectivity was poor on the type scale. The degree of utilization and degree distribution, average path length and clustering coefficient were used to analyze the characteristics of grassland landscape network. Five nodes with a degree of 6 were found in the grassland landscape network. The maximum value was 8, with 2 nodes, and the average path length was 1.6061. The results showed that the grassland landscape network had obvious nonuniformity. The research results had practical significance for the structural optimization of the grassland landscape in Baotou City and the stable development of the structure.

Abstract:To understand the adaptation mechanism of plants to the urban ecological environment from the perspective of functional ecology, three common tree species (Fraxinus chinensis, Sophora japonica and Koelreuteria paniculata) planted in three different treatment plots: pervious brick pavement with a permeability coefficient of more than 0.4mm/s, impervious brick pavement with a permeability coefficient near zero, and nonpavement were selected to understand the effects of pavement on leaf functional characteristics and leaf economics spectrum. The result showed that surface temperature was significantly higher in the pavement treatments than that in the control treatment (P<0.01), with a higher surface temperature noted for the pervious pavement than that for the nonpavement. Soil moisture content was significantly lower in the impervious pavement treatment than that in the pervious pavement and control treatments (P<0.01). Pavement caused heat stress on Sophora japonica and Koelreuteria paniculate, and the impervious pavement caused drought stress on Fraxinus chinensis growth. Leaf functional traits showed relatively consistent ecological countermeasures to adapt to urban environmental changes. Pearson analyses indicated that leaf chlorophyll showed significant positive correlation with specific leaf area (P<0.05), and highly significant negative correlation with leaf dry matter content and leaf tissue density, respectively (P<0.01). Leaf dry matter content showed highly significant negative correlation leaf tissue density (P<0.01). The results indicated that a spectrum of leaf economics also existed in urban pavement environment, and that of the represent species was generally more biased toward the fast investmentreturn on the leaf economics spectrum. In urban pavement environment, plants would increase leaf dry matter content, leaf tissue density, and reduce stomatal area, stomatal density, and specific leaf area to adapt to special habitats at high temperature and drought stress. Thus, it was necessary to select heat and drought tolerant tree species, manage land with shadowing or irrigation, and reduce trimming branches, in order to guarantee tree growth in paved urban environments.

Abstract:To describe the integrity, stability and health of forest ecosystem more objectively and meticulously, and provide scientific basis and decision support for the protection of forest resources at the source and the rational management and management of forest resources, based on the forest resources inventory data, DEM data and social and economic data in Yi County, Hebei Province, the forest landscape types, quantity and distribution of township scale were analyzed by using landscape index, structural equation model and statistical method. The characteristics of forest landscape pattern and its influence mechanism were studied under the dominance of natural geography, social economy and land exploitation and utilization. The following results were obtained: the forest landscape resources of the western mountainous areas were obvious, while the eastern plain villages and towns were smaller. The forest resources were mainly distributed in 100~300m hilly areas and in the middle mountains of 500~800m. At the landscape and type level, the forest resources of the villages and towns in the eastern plain were relatively small. Patches density (PD) and cohesion (COHESION) were more responsive to geographical environment dominance and human activity interference. There was a close relationship between low fragmentation, high connectivity, diverse forest landscape and high elevation, high undulating terrain conditions. The larger the area ratio of proportion of cultivated land area and proportion of resident construction land area (PCLA, PRCLA) was, the lower the degree of fragmentation and connectivity of forest landscape was. Mean slope (MS), soil depth (SD) and elevation difference (ED) as the basic control factors directly influenced the cultivated land and the inhabitant construction land proportion and so on, and it had an indirect action on the forest landscape pattern. Under certain topographic and soil conditions, reducing average population size (APS), the proportion of PCLA and PRCLA can reduce the fragmentation of forest landscape pattern and enhance the connectivity of forest landscape.

Abstract:In order to further study the interaction between shallow groundwater, vegetation and soil of arid and semiarid regions, the database of the Sentinel-1A, Landsat images, soil moisture and the groundwater depth were utilized to quantitatively analyze the information of soil moisture and groundwater depth in the study area by the model of support vector machine (SVM) regression algorithm. Furthermore, the comparison of optical remote sensing and microwave remote sensing collaborative inversion in soil moisture and groundwater depth was also analyzed. By the survey of soil moisture and groundwater depth in the study area, the results indicated that the highest accuracy in SVM model was the correlation between soil water content in 0~10cm and groundwater depth. The accuracy of temperature vegetation drought index (TVDI) was improved, through the C calibration model. It was feasible to invert the groundwater depth by SVM model with different parameters. For single factor modeling, the model constructed by TVDIMSAVI had the highest accuracy and the R2 of modeling set was 0.74, the value of RMSE was 4.66%, and the R2 of verification set was 0.70, the value of RMSE was 4.65%, compared with only single factor (σ0soil or TVDI), σ0soil and TVDIMSAVI combination work with the highest model accuracy, R2 was 0.86, and RMSE was 4.16%, the R2 of verification set was 0.92, and RMSE was 2.73%. The results of the optimal model parameters were used to retrieve the soil moisture and groundwater with good accurate. The average relative error of groundwater was 8.23%, which was better than the previous results of the study area of 18.06%.

Abstract:In order to explore the effect of applying biochar on the posteffects of soil hydrodynamic parameters on different slopes, the experimental study on soil hydrodynamic effects was carried out for two consecutive years after the application of biochar under three kinds of terrain slope conditions. The effects of biochar applied to different slopes on soil water constant, soil water characteristic curve, specific water capacity, unsaturated hydraulic conductivity K(h) and unsaturated diffusion rate D(θ) were investigated. The results showed that the application of biochar could increase the soil water holding capacity and saturated water content in the same year and the next year, and the growth rate was increased with the increase of slope. Biochar factors had significant effects on soil water constants within two years (P<0.015), while slope factors had no significant effect (P>0.05), which meant that biochar factors were more pronounced. Within two years, the soil moisture content was increased under various soil suction conditions, soil water holding capacity was increased, and it was positively correlated with slope of terrain and negatively correlated with age. Biochar increased the soil specific water capacity within two years, and the water supply capacity was strengthened, the maximum water capacity increase was 1830207×10-3cm3/cm4. The slope of terrain had no obvious effect on K(h), but the application of biochar could increase K(h) and the soil water conductivity was enhanced. In 2016 and 2017, K(h) was increased by a maximum of 239.61% and 164.04%, respectively. The application of biochar could reduce D(θ) and inhibit the horizontal movement of soil moisture. As the increase of slope of terrain, the suppression effect was enhanced. The effect of biochar application on the soil hydrodynamic parameters in the first year was greater than that in the next year. The research results can provide a theoretical basis for the protection and utilization of agricultural soil and water in sloping farmland in the black soil region of Northeast China.

Abstract:In order to reveal the interaction between biochar and nitrogen on affecting the root morphology and system architecture of cotton during fullbloom stage, the root systems and root growth angles of cotton by layered digging at 0~10cm soil layers and below were analyzed through the generalized additive model and redundancy analysis under different biochar application regimes(N0(conventional nitrogen application, 0.3t/hm2), N0+ Bc1%(N0+ 1% cotton biochar as quality of topsoil), Nl+ Bc1%(0.21t/hm2+ 1% cotton biochar as quality of topsoil), Nl+ Bc2%(0.21t/hm2+2% cotton biochar as quality of topsoil)and N0+Bc4%(N0+4% cotton biochar as quality of topsoil). The results showed that there was no significant difference between Nl+Bc2% and N0+Bc1% in average fine root length, but it was significantly higher than those of N0+bc4%, Nl+Bc1% and N0(p<0.05). The average root branch angle was 83°17′ at 0~10cm soil layers and it showed no significance between each group(p>0.05), however, root branching angle was significantly larger at deeper soil, and root branching angle was 101°48′ under Nl+Bc2%. Biochar application changed the cotton root spacing section(p<0.001), and it was more significantly changed in direction with water coming of 270°, where the longest was 4cm under N0+Bc4%. The specific root length density of cotton was altered by biochar application regimes(p<0.02)and soil depth(p<0.001)separately. The redundancy analysis showed that the main factors influencing the root length density were the vertical angle of fine and medium roots in the topsoil, the vertical angle of fine root in the bottom and the percentages of very fine root length. Among root traits, the fine root length was most closely related to vertical root angle. This suggested that vertical root distribution constitutively affected fine root length. Significant genotypic variation existed in the root diameter and root growth angle in interaction with biochar and nitrogen. To sum up, the application of 0.21t/hm2 nitrogen with biochar of 1%~2% topsoil mass mainly changed the root system architecture and morphology of cotton at the bottom soil(>10cm)and 2% biochar made up for the negative effect of nitrogen deficiency.

Abstract:Based on a 9year field experiment, the effects of tillage systems on waterstable aggregate content, soil organic carbon (SOC) content, wheat yield and soil water use efficiency (WUE) were investigated under the two planting methods (wheat continuous cropping and wheat/maize rotation ) in dark loess of Weibei Highland. The results showed that the content of water stable macroaggregate with diameter lager than 0.25mm (R0.25), mean weight diameter (MWD), SOC content, the aggregateassociated organic carbon of all size classes and water use efficiency (WUE) under wheat/maize rotation were mostly higher than those under the wheat continuous cropping in 0~20cm soil layer. Compared with the conventional tillage, the measures of notillage (NN), subsoiling (SS) and notillagesubsoiling (NS) mainly increased soil R0.25, SOC, the aggregateassociated organic carbon of all size classes and the contribution of soil organic carbon in water stable macroaggregate with a diameter lager than 0.25mm to total soil organic carbon (ISOC0.25) in 0~10cm soil layer. In the soil layer below 10cm, the SOC content of NS treatment was increased, and the measures of NS also increased soil R0.25, the aggregateassociated organic carbon of all size classes and ISOC0.25 in soil layer of 35~50cm. Compared with the conventional tillage, the measures of NS increased wheat yield and WUE significantly, by 14.25% and 19.30% for wheat yield, by 24.98% and 9.89% for WUE in wheat continuous cropping and wheat/maize rotation, respectively. Generally, compared with the wheat continuous cropping, wheat/maize rotation was more beneficial to improving soil structure, increasing SOC content and WUE; and the tillage of NS was the most suitable measure for the local soil conditions.

Abstract:Oxyfertigation delivers water, fertilizer and gas coupled mixture to crop root zone via subsurface drip irrigation system. This new technique changes the oxygen concentration and water distribution in soil and thus affecting the nitrogen cycling process, including nitrification and denitrification, and then affecting soil nitrous oxide (N2O) emissions. However, the influences of oxyfertigation on soil N2O emissions from greenhouse vegetable fields and its main influencing factors were both little known. To understand the influence of aeration, nitrogen application and irrigation on pepper soil N2O emission in greenhouse, totally eight combinations were tested, including two types of nitrogen application rates (300kg/hm2 and 225kg/hm2), two types of aeration levels (40mg/L and 5mg/L), and two types of irrigation amount (1.0W and 0.6W, W was full irrigation amount). Soil N2O emission flux was monitored via using static chambergas chromatograph technique. Soil temperature, waterfilled pore space (WFPS), dissolved oxygen (DO), NO-3N and NH+4N content were also measured. Quantitative contribution of influential factors to N2O emission under oxyfertigation was analyzed by structural equation model (SEM). Results showed that aeration, the increase of nitrogen rate and water amount resulted in an increase of soil N2O emission peak, cumulative N2O emission and yieldscaled N2O emission under oxyfertigation. Compared with control, the cumulative N2O emission of aeration condition was averagely increased by 31.90%. The cumulative N2O emission under full irrigation was averagely increased by 43.22% compared with deficit irrigation. Similarly cumulative N2O emission under conventional nitrogen rate was averagely increased by 33.01% compared with the 75% conventional nitrogen rate treatment. Aeration and the increase of water amount resulted in an increase of crop nitrogen use efficiency. However, the increase of nitrogen rate caused a decrease of crop nitrogen use efficiency. Considering crop yield, nitrogen use efficiency and yieldscaled N2O emission, the treatment of 75% conventional nitrogen rate aerated deficit irrigation was an optimal combination under oxyfertigation. The path coefficients of soil temperature, WFPS and NO-3N content were 42%, 60% and 58%, respectively. And soil temperature, WFPS and NO-3N content were identified as main influential factors. The research result provided a reference for the selection of water, gas and nitrogen coupling management and demonstrated the great significance in knowledge of soil N2O emission under oxyfertigation.

Abstract:The intervalparameter twostage robust stochastic programming model (ITRM) was put forward for supporting optimization and management of water resources in Mudanjiang Irrigation District, Sanjiang Plain, which was in such a situation, with multiwater source, multicrop and multirobustness coefficient. The ITRM incorporated intervalparameter programming (IPP) and twostage stochastic programming (TSP) with a robust optimization framework to deal with uncertainties. Compared with the traditional TSP, ITRM can overcome the deficiency of uncontrollable risk in system. The robustness coefficient was introduced to represent the system risk, which was effectively reflected in the model. Let the robust coefficient be 0, 0.4, 1, 2，3 and 5, respectively. With the increase of robust coefficient, the feasibility of the model and the stability of the system were enhanced. It was a sufficient and effective balance between system cost and risk when the robustness coefficient was 3. A more stable allocation of water resources was generated and the system cost was between 1.90327×109 RMB and 2.63475×109 RMB. Based on this model, a series of scenarios under different levels of preallocation water was done and different degrees of water surplus and shortage were obtained correspondingly. All these results were valuable for watersaving irrigation agriculture and improving water use efficiency and economic value, and thus it provided a technical support for decision maker in reasonable allocation of agricultural water resources.

Abstract:Aimming to investigate the jet flow and the switching technology that form the pulse flow and the anticlogging ability in drip irrigation emitter. Six kinds of sediment particle size segments less than 0.1mm were sorted by screening and organized into three types. Sediment grading combination concentrations were 0.5g/L, 1.0g/L and 1.5g/L, with total inlet pressure of 0.1MPa, and the anticlogging characteristics of the drip irrigation test system under jet tee and tee conditions were analyzed. Results showed that the jet tee can generate pulse amplitude of 27kPa, with oscillating frequency of 236 times/min and pulse current of 0.5g/L and 1.0g/L of sediment graded water with strong anticlogging ability, and the anticlogging ability of 0.03~0.05mm and 0~0.03mm of sediment particle size was more significant, and the anticlogging energy of 0.05~0.10mm of sediment particle size was increased with the increase of concentration. The force showed a weakening trend, and the average number of irrigations of the jet tee test system was 3～8 times more than that under tee conditions. The average test system of the jet tee at different sediment concentrations was relatively moderate, while the flow rate and irrigation uniformity was higher than that under the tee conditions. The pulse water pressure generated by the jet tee was the main reason for the anticlogging ability of the emitter, which was superior than that under the tee conditions.

Abstract:A new type of mobile fast pyrolysis equipment with annular tube fluidized bed reactor was designed and built throughput capacity of over 50kg/h. The structure of main components such as the annular tube fluidized bed reactor, fluidized pneumatic conveying feeder, jetspray combined condenser and so on was described in detail, and the experiments were carried out to test the performance of each part of the mobile fast pyrolysis equipment. The results showed that the feeding rate was greatly influenced by the injection gas velocity, and was less affected by the fluidized gas velocity. When the fluidized gas velocity was 0.02m/s, as the injection gas velocity was increased, the feeding rate was increased, whereas the injection gas velocity exceeded 8m/s, the trend was slowed and the feeding rate fluctuation range became larger. The annular tube fluidized bed reactor was heated by means of burning liquefied petroleum gas and noncondensable gas, and the internal temperature field of the fluidized bed reactor was stable, which met the needs of biomass thermal cracking. Jetspray combined condenser was suitable for the cooling of the pyrolysis volatiles. In order to increase the yield of biooil, a larger spray flow rate and jet flow rate were required at a given temperature. At reaction temperature of 500℃, the highest biooil yield of larch sawdust could reach 68.6%. The research can provide a referenced basis for the mobile biomass pyrolysis liquefaction demonstration plant.

Abstract:Aiming to combine the advantage of photofermentation and darkfermentation for biohydrogen production, the mixed photosynthetic and anaerobic bacteria consortium (MPAC) was used to study the cofermentative hydrogen production. The kinetic characteristics of cofermentative hydrogen production by MPAC were studied. The kinetic models of cell growth, substrate utilization and hydrogen production of cofermentative hydrogen production by MPAC were established. The illumination factor was firstly introduced into the kinetic model of biohydrogen production. The nonlinear differential equation was solved by homotopy perturbation method (HPM) and the kinetic models were obtained. By comparing with the experimental data, the model can be consistent with the experimental data, which can well reflect the change of biomass concentration, substrate concentration and hydrogen production in the process of cofermentative hydrogen production. The relationship between the kinetic parameters and the sensitivity of the three established kinetic models were analyzed. The results showed that the maximum specific growth rate of the kinetic models had the biggest influence on the results, and the change of the cell growth reached 79%, the change of substrate concentration reached 118%, and the change of hydrogen produced reached 98.4%. The three established models were suitable for describing the kinetic characteristics of biohydrogen production.

Abstract:Four kinds of skeletons (no branching, two “one divided two” and “one divided three” structures) were designed based on the branching structure of Euryale veins and the stability characteristics of the triangle. Static and linear buckling analysis were carried out by ANSYS finite element analysis software, the static analysis showed that there were significant differences among the four greenhouses under the load combination two (wind load combination), the values of displacement and strength were reduced by 98.92% and 86.46% with the increase of bifurcate series, respectively, and “one divided twoall triangle” and “one divided three” met the strength requirement and their mechanical properties were similar, but “one divided twoall triangle” saved more material; buckling analysis showed that under vertical and horizontal loads, the buckling loads were 63.52～26737.22 times and 26.86～11300.97 times of the allowable loads (limits based on the element lengths), which illustrated the four greenhouses all satisfied the stability requirement and significant response to vertical loads (the buckling load was increased by nearly three times due to bifurcation structure). Therefore, the one divided twoall triangle was the optimal structure. The number of groups which had no significant difference with simulation results accounted for 75% and 25% existed slightly deviations among the 12 groups of strain tests in scale model that was made according to 1∶25, and the test relative errors were 0.18%～0.69%, which showed the simulation process was accurate and reliable. The response of horizontal beams to combination one (snow load combination) was obvious, and the strain mean of each group under combination one was 5.6 times of that under combination two, and the combination two had significant effect on vertical beams, which was characterized by the strain mean of each group under combination two, and it was 6.2 times of that under combination one.

Abstract:Different inoculum and substrate ratio (ISR) was taken to conduct the anaerobic digestion of orange pressing waste (OPR), and the daily production of methane was recorded. The relative abundance of bacteria and archaea in the inoculum and sludge were tested to find out the change before and after anaerobic digestion. And the digested materials were used for the test on the improvement of anaerobic digestion after acclimation of inoculum. The results demonstrated that the cumulative methane production of ISR 8, 6 and 4 were 320.0mL/g, 304.9mL/g and 242.6mL/g, respectively, but that of ISR 2 was only 111.4mL/g after a lag phase of 7d. And the relative abundance of bacterial and archaea community of ISR 2 was quite different from those in other tests. The relative abundance of Bacilli, Methanosaeta and Methanospirillum was decreased to 1.88%, 24.45% and 1.71%, respectively, which may cause the insufficient degradation of the substrate. Although there was no increase in the cumulative methane production in the 2nd and 3rd rounds of anaerobic digestion, the time employed to reach the final methane production was shorter than that in the 1st round of ISR 8 and 6, and the cumulative methane production of the first 4d was 95.75% and 93.40% of the total production in the 3rd rounds. But it was unstable when ISR 4 was taken to conduct the test. In this situation, the improvement of anaerobic digestion would be decided by the source of the inoculum, and no improvement was found in the 2nd and 3rd rounds if the ISR was 2. According to the results, the optimum ISR for the anaerobic digestion of OPR was 6 whether in a test on the biomethane production from different OPR or in a pretreatment unit for the improvement of the methane production, and at least a round of anaerobic digestion was needed for the acclimation of the inoculum.

Abstract:Protein content is one of the most important quality indicators of milk. The traditional methods used to measure protein content in milk have high precision, but the measurement procedures are tedious and timeconsuming, and the measurement equipments are expensive. In addition, these methods can not be used in field or insitu measurement. Therefore, developing a kind of portable milk protein content detector with simple operation and low cost, which could be used insitu measurement, would be appreciated by milk producers, processers and consumers. Since the hydrophobic grouping of Coomassie brilliant blue G-250 has strong affinity for protein in acids, a portable milk protein content detector was developed based on light transmission. The hardware of the detector consisted of the modules of single chip microcomputer, light source, light sensor, input/ouput and power. The software was developed by C51 language, and was made up of main function and several subfunctions to realize light collection, data preprocessing, protein content calculation and display. Raw fresh milk was used to study the relationship between intensity of transmitted light and protein content. It was found that the intensity of transmitted light was decreased with the increase of protein content, and they had strong linear relationship with the coefficient of determination of 0.872. The validation experiment on the developed detector showed that contrasted with Kjeldahl method, the absolute measurement error of the developed detector was within the range of ±0.08g/(100g), and its mean absolute error was 0.05g/(100g). In addition, the measurement result could be given in 2s.

Abstract:Precooling is one of the key measurements for litchi fruit preservation after being harvested, and the performance of precooling has a great influence on the quality change of litchi fruit. In order to investigate the heat and mass transfer during the precooling process, a mathematical model was built to describe the heat and mass transfer phenomenon in the test bed with controlled atmosphere for fruits and vegetables. The mathematical model was built based on the theory in heat dynamic mass transfer, and the temperature and moisture loss of the litchi fruit during precooling process was calculated. The effects of fruit weight and initial temperature on the process were investigated. After that, some results can be made. The time of precooling became longer as the weight of fruit was increased, however, the speed of moisture loss would be decreased. When there were 10kg litchi fruits, it took about 350min for the temperature of fruit decrease from 25℃to 5℃ by the same stack method, and the weight loss rate was roughly 2.16% after precooling. It can also be drawn that the speed of weight loss can be reduced by decreasing the initial temperature of litchi fruit. A test was done to verify the accuracy of the model, and the test results were matched well with the results from calculation, the maximum difference between them in fruit temperature and weight loss rate was 2.8K and 0.3%, and the mean difference rate was 13.1% and 10.7%, respectively. The research results can be useful for the investigation of the heat and mass transfer mechanism in a cool room and can be used to predict the temperature and weight loss of fruits during precooling process.

Abstract:The reconstituted emulsion prepared by soybean protein isolate and anthocyanin was studied. Dynamic light scattering (DLS) was used to evaluate the effect of anthocyanin on the size and distribution of reconstituted emulsion. And the stability of reconstituted emulsion was evaluated by emulsion stability and Zeta potential analysis. The results showed that the particle size of the reconstituted emulsion became smaller, the stability of emulsion was decreased significantly, and the absolute value of ζpotential was increased. The sample of 40 (mass ratio of SPI by heat treatment to anthocyanin) had the lowest CI value (41%) and the maximum ζpotential, which indicated that the reconstituted emulsion with certain amount of anthocyanins had the best stability. At the same time, the stability of emulsion oxidation showed that the scavenging ability of DPPH and ABTS was increased first and then decreased slightly with the increase of concentration of anthocyanin. And the reconstituted ratio of SPI by heat treatment to anthocyanin was 40, the antioxidant property of emulsion was the best. Therefore, the addition of anthocyanin could effectively improve the oxidation stability of the reconstituted emulsion.

Abstract:By inoculating Lactobacillus sake and Staphylococcus xylose, the experiment was divided into compound fermentation group, a single Lactobacillus sake group, and control by natural fermentation, the effect of different starter cultures on lipolysis, proteolysis and flavor formation in the fermented mutton sausages was explored. The results showed that the addition of compound starters promoted the rapid acidification of sausage, and the pH value of mixed group was reduced to 4.6, which was significantly lower than the safe acidity of the fermented meat products of 5.3 and other groups （P<0.05). The pH drop caused the water activity (aw) and nitrite residue in the mixed group to be significantly lower than those in the single, control and raw meat groups （P<0.05), and the redness color (a*) of the mixed group was the best. The content of free fatty acids in sausages was increased gradually. The content of monounsaturated fatty acids in sausages at the end of maturity was significantly higher than that in the single and control groups （P<0.05), and the contents of saturated and polyunsaturated fatty acids in the control group were the highest, all which indicated that the mixed starters contributed to the release of monounsaturated fatty acids, while endogenous lipase played a key role in the release of saturated and polyunsaturated fatty acids. The proteolysis showed that the proteolytic index (PI) and free amino acids content of the starter group were higher than those of the control group, but the difference was not significant （P>0.05). Totally 45 kinds of flavor substances were detected in the inoculated, which were higher than 44 kinds in the control group and 27 kinds of raw meat （P<0.05). The mixed starters improved the characteristic flavor content of the sausage, such as 3methylbutanal, aldehyde, heptaldehyde, nnonanal and other aldehydes. In summary, the addition of compound starters helped to shorten the fermentation period, increase the content of monounsaturated fatty acid, and improve the color and flavor sensory quality of sausages.

Abstract:High pressure homogenization is one of the most common physical modification methods in protein processing. However, the pressure of homogenization generally does not exceed 40MPa in actual production due to the limitation of equipment. Therefore, it is of great importance to study the effect of low pressure homogenization (0~40MPa) on the solubility and structure of soybean protein isolate. The effects of lowpressure homogenization (0~40MPa) on the solubility and structure of soybean protein isolate (SPI) were studied by measuring particle size distribution, solubility, emulsification, tertiary structure and thermal stability. The results showed that lowpressure homogenization treatment could reduce the particle size of SPI, significantly improve the solubility, and the solubility was positively correlated with emulsifying ability and emulsifying stability. The linear fitting model functions were obtained, and the correlation coefficients were 0.9568 and 0.9625, respectively. Fluorescence spectrum analysis showed that the structure of SPI was expanded with the increase of homogeneous pressure, the maximum absorption wavelength was redshifted, the internal tryptophan group was exposed, and the fluorescence intensity was increased with the increase of homogeneous pressure. At 30MPa, the fluorescence intensity was the highest. When homogeneous pressure was further increased, the protein molecules were aggregated, and the former exposed active groups were hided in the inside of SPI with a slight decrease in fluorescence intensity due to inward crimping of active groups. The above results were verified by the analysis results of thermal stability.

Abstract:Steering wheel angle detection is one of the key technologies to realize automatic navigation of agricultural machinery. The measurement results of agricultural machinery steering wheel angle directly affect the accuracy of automatic navigation control and the effect of agricultural machinery operation. Taking the Lovol M904-D wheeled tractor as the research platform, the WYH-3 noncontact angle sensor was used to study the calibration and detection method of steering wheel angle of wheeled tractor. The installation method of tractor steering wheel angle sensor was introduced. The relationship between angle sensor and agricultural machine steering angle was calibrated by scaled dial. The calibration results showed that the correlation was significantly and the coefficient was over 0.99. Focusing on the bias error in the wheel angle calibration test, a curve optimization fitting method based on the least squares principle was proposed to estimate the position deviation of the wheel relative to 0°. Preview tracking model based path tracking test showed that the extreme value of navigation control deviation was 2.74cm, the average absolute value of deviation was 0.49cm, and the standard deviation was 0.58cm. It indicated that the path tracking control precision was high, and the feasibility and accuracy of the steering wheel angle detection scheme were verified. 

Abstract:An appropriate stepsize is required to be set up when using rapidly exploringrandom tree (RRT) to perform path planning of a robot, 〖JP2〗which needs user to proceed debugging the program and it’sgenerally timeconsuming, also a fixed stepsize in RRT always resulting in invalid collisiontest. Aiming at solving the above problems existing in RRT, a selfadaptive stepsize RRT was proposed. The matrix operator norm induced from configuration space norm and work space norm was founded based on Jacobi matrix and the norm inequality of configuration space and work space was established, by the means of which the displacement of robot caused by each stepsize in configuration space was limited in allowed magnitude which validated collision test. In order to coordinate dualrobot, passive growing of random tree algorithm was put forward. The algorithm can control the growth of random tree of dualrobot in different configuration spaces, and then the motion of dualrobot was coordinated to ensure generating cooperation path in work space. Numerical experiment indicated that the selfadaptive stepsize RRT can bound the displacement of each step within the value set up at beginning of algorithm which guaranteed the effectiveness of collision test. Compared with standard fixed stepsize RRT, selfadaptive stepsize RRT omitted the process of determining stepsize only needed to set maximum value of stepsize in work space which improved the efficiency of path planning. The algorithm proposed can provide a new perspective on the path planning of dualarm robot.

Abstract:Variabledisplacement asymmetric axial piston pump (VDAAPP) directly control single piston rod hydraulic cylinder closed loop system has the advantages of compact structure and high energy efficiency. In order to develop VDAAPP, according to the fixeddisplacement asymmetric axial piston pump with three flow distribution windows, a PD variable displacement control scheme based on position feedback of swashplate angle was proposed. The mathematical model of VDAAPP was established. The factors affecting the frequency response of VDAAPP were analyzed by using approximate linearization and order reduction methods. The resistance torque of swashplate was also studied. The electrohydraulic simulation model of VDAAPP was established in AMESim. The correctness of the resistance moment formula was verified by simulation analysis of force characteristics of swashplate. The experimental platform of VDAAPP was built to test the dynamic performance of the system. The results of experiment and simulation showed that when VDAAPP sucked oil by one flow distribution window and discharged oil by two flow distribution windows, the VDAAPP swashplate had a large oneway resistance moment, which would reduce the dynamic response of the swashplate in the process of reducing the swashplate angle; when the PD control was used and the proportional gain kp was 3, VDAAPP can achieve zero overshoot variable displacement control and had high response speed, which demonstrated the rationality of the proposed control scheme.

Abstract:Mechanical design is an important guarantee for the quality of entire mechanical engineering, and the traditional mechanical design cannot meet the current needs, therefore, the development of intelligent mechanical design has become an inevitable trend. Intelligent design was researched and applied in the field of machinery, but research and application in the field of agricultural equipment was still in its infancy. In the intelligent design process of agricultural equipment, it was necessary to establish a design system, including model library, knowledge base, inference engine and intelligent assembly. For the mechanism with motion attribute in the system model library, the digital prototype can replace the physical prototype for the designer to analyze the performance and parameters related to the motion, which required the addition of motion simulation function module in the intelligent design system to test the motion characteristics of the mechanism in the model library and obtain its motion parameters. Aiming at the problems involved that the multiply of defined motion pairs elements, the cumbersome operation, the strong professional operation, the timeconsuming conversion of the model between platforms, and the low efficiency in the process of creating a motion mechanism. An interactive creation system for motion mechanism was researched, the motion mechanism was created through humancomputer interaction, which was convenient for users to quickly obtain the kinematic parameters of the mechanism, and provide reference for the design of the mechanism. On the CATIA DMU (Digital mockup) motion mechanism workbench, the package command of the creation of motion mechanism was intended to weaken the limitations of professional background knowledge, which was based on the holographic model library of the intelligent design system of agricultural machinery and equipment, using secondary development interface of software of computer aided tridimensional interface application (CATIA) with the development language Visual Basic and Windows API function. The cutting table of combine was used as the system test object, the motion relationship between the parts was analyzed, the composition of the motion pairs was defined, the construction elements of the motion pairs were perfected by model preprocessing, the construction elements were renamed on the structure tree according to the identification rules, the information of which was exported and stored. The result of the test indicated that the system was feasible and effective, and the study promoted the acquisition of the kinematic parameters of the mechanism, and also provided a common basic technology for the research of the intelligent design system of agricultural machinery.

Abstract:Topological structure is the most original part of mechanical system design. The premise of structure synthesis depends on complete description and accurate analysis of the motion characteristics. And the motion characteristic is not only the design objective of type synthesis, but also the judgment whether the obtained mechanism meets the requirements. The existing indexes of motion characteristics only contain three kinds of information: motion type (translation and rotation), motion direction and the dimension of motion space, but they lack the overall geometric shape of motion space, which will lead to insufficient information of motion characteristics and incomplete type expressions. To solve this problem, a geometric description and analysis method for the motion characteristics of robot endeffector was proposed based on Gaussian geometry. Firstly, a geometric description model of motion characteristics was established, which included overall geometric shape of motion space. Secondly, the relevant operation rules of motion characteristics were formulated, which made the intersection of all limbs’ motion characteristics for parallel mechanism relatively straightforward and simple. And a geometric analysis method for the motion characteristics of robot endeffector was presented. Finally, the validity of the geometric description and analysis method was verified by some concrete examples. Compared with the algebraic method, the geometric analysis method for the motion characteristics of the robot endeffector was much simpler and more intuitive, which had obvious advantages especially for mechanisms with bending motion characteristics.

Abstract:Industrial serial robot has not only large geometric errors, but also nongeometric errors that can not be ignored, which limits its application in the field of high accuracy. A complete rigidflexible coupling position error model, including geometric and compliance errors was established, and a modified Levenberg-Marquardt algorithm (M-LMA) based on the predictive residual errors and the weighted recursive average filtering algorithm was used to identify the coupling error parameters. In order to improve the efficiency and reliability of the measurement process, an intelligent selection method of the measuring poses based on the linearly decreasing weight particle swarm optimization algorithm (LDW-PSOA) was proposed, which combined the external constraints of the detection features of the measuring equipment and the geometric characteristics of the endeffector. A local precise compensation method was proposed, which can be used simultaneously with the calibration or the global compensation respectively, and can also be applied directly alone. Meanwhile, a model optimization method based on the prediction accuracy and the number of parameters was proposed according to the characteristics of the robot and processing demands, and a multimode accuracy improvement strategy was formulated. Furthermore, the established models and the proposed algorithms were integrated into the development platform of Matlab to realize a GUI interface system. Finally, the experimental results showed that the proposed accuracy improvement strategy can not only achieve the performance of highprecision positioning of the robot in many ways, but also had an efficient and reliable measurement process.

Abstract:According to the topological design theory of parallel mechanism (PM) based on position and orientation characteristic (POC) equations, a three degreesoffreedom (DOF) 3Pa+2RSS PM was designed. The main topological characteristics such as the POC set, DOF and coupling degree(κ) were calculated. It was proved that the coupling degree of the PM equaled to 1(κ=1) by using the formula of coupling degree. Afterward, a forward solution model for the kinematics modeling principle based on ordered single open chain (SOC) units method was established. Then the forward kinematics was solved by using onedimensional search method. The inverse kinematic formulas were derived by establishing the relationship between the input variables and output variables. Meanwhile, the Jacobian matrices were derived by inverse kinematic formulas which were used to analyze the geometric conditions of three kinds of singular positions for the PM. In order to enlarge the workspace of the mechanism, two RSS chains were replaced by using RUU chains under the premise of constant degreesoffreedom, output characteristic and kinematics analysis. The workspace boundary and singularities inside the workspace of the mechanism were analyzed by using the discretization method and calculated in Matlab. The result turned out that the shape of workspace boundary of the mechanism was regular and large. Also the free singularities area inside the workspace was large. The research laid a theoretical foundation for the stiffness, dynamics investigation and prototype design of the PM in the future.

Abstract:In order to improve the cavitation characteristics of cycloidal gerotor pump, a convex tongue oil groove structure was put forward with an increasing limit of oil flow, and the structure model of cycloidal gerotor pump convex tongue was established. The RNG k-ε turbulence model was used to simulate the internal cavitation flow of cycloidal gerotor pump under different working conditions, the cavitation characteristics of cycloidal gerotor pump convex tongue oil groove were analyzed at different speeds and rotor positions, and the gas rate and axial gas bearing rate of different monitoring points were further studied. And the cavitation characteristics of the cycloidal gerotor pump at different rotation speeds and different inlet pressure conditions were tested and compared. The results showed that the structure of the convex tongue can reduce the cavitation at three kinds of rotational speed, the improved cavitation position was mainly located near the maximum intertooth volume; the convexity groove had the most obvious improvement in the air rate of the rotor region at high speed, less effective at low speed; the cavitation along the axial direction had an inhomogeneity, the bottom cavitation was more serious in the minimum intertooth volume of the inlet side, and the cavitation in the upper part of the rotor was more serious in the larger tooth space. The volumetric efficiency simulation value of the cycloidal rotor pump was in good agreement with the experimental value. The volumetric efficiency of the tongue oil groove was higher than that of the original model under different inlet pressures, and the cavitation characteristics of the tongue oil groove were better than that of the original model.

Abstract:External gear pumps are mostly used in open hydraulic circuit, such as transmission, pressurization, fuel injection and lubrication, etc. Because of the low suction pressure of the pump, air will be mixed into oil inevitably, which has a negative impact on the hydraulic system. In some special occasions, such as high altitude hydraulic system, because the equipment works at high altitude environment, the suction pressure of the fuel pump (e.g. gear pump) will be lower than the ordinary atmospheric pressure, which will undoubtedly lead to underpressure suction of the gear pump and aggravate the cavitation phenomenon. In order to study the influence of high altitude working environment on the performance of gear pump, it is very important to fully understand the flow law of oil in gear pump and analyze the influence of oil suction pressure on its cavitation characteristics. In order to study the influence of suction pressure on cavitation characteristics of external gear pump, numerical simulation and visualization test method were used to analyze an involute external gear pump. The gear pump was widely used in fuel injection system. The simulation and test were carried out at 0.05MPa，0.10MPa and 0.15MPa, respectively. The vapor volume fraction distribution of the gear pumps internal flow field was numerically simulated. The actual flow state, bubble size, number of bubbles and cavitation degree in the gear pump were recorded and observed. The results showed that at different suction pressures, the fluid in the gear pump would have different degrees of cavitation. The cavitation intensity from strong to weak was as following: vortex flow, veil flow and bubbles. With the increase of suction pressure, the number and volume of bubbles of the oil would be decreased gradually, which would reduce the max value of vapor volume fraction and cavitation degree of the oil, made the flow state of the oil more and more stable, and then improved the continuity and stability of gear pumps outlet flow.