Abstract:The control system is one of essential constitute parts of the fruit harvesting robots, which affects the work efficiency and quality of the robots. In generally, fruit harvesting robots are nonlinear spatial open chains with multiinput and multioutput and serious coupling. It is difficult to set up accuracy mathematical model for the joint control system because there are many uncertain factors during working, such as joint friction, assembly errors, etc. Sliding mode control method has more advantages to solve nonlinear problems with strong robustness, antidisturbance, etc. To improve the control performance of the fruit harvesting robot and solve the vibration of the control system, the sliding mode control (SMC) method based on genetic algorithm (GA) optimization was proposed. In this method, the parameters of SMC algorithm were optimized by GA through adjusting the parameters of switching function and exponential approach law in real time. Simulation and experimental platforms of a joint control system were designed and manufactured based on STM32 microcontroller, AS5045 position feedback module and CAN bus communication module. Moreover, experiments on position tracking and joint control system response were conducted in unloading and loading conditions respectively. The results show that the response velocity of position tracking was increased greatly by adopting GA. The vibration amplitude and time of the control system caused by external disturbance and load changes were reduced significantly. The experiment results also showed that the response time during position tracking of joint No.6 in the unloading condition is 0.3s shorter than that in the loading condition. However, the position tracking accuracy and maximum deviation are not affected greatly by adding load. In addition, the controller response time in actual experiments increases 0.5s comparing with that of simulation experiment owing to ignoring some uncertain factors, such as joint friction, assembly errors, inertia force, etc. in the simulation experiment system. But the control system can make the joint to track the expected trajectory with satisfied accuracy and high robustness. The results can provide the foundation for the further research of the robot joints’ control systems.

Abstract:Seedlings need to be transplanted from high density into lower density trays for more space to grow in the greenhouse. Automatic transplanter could detect seedlings health state and do the tasks of lower density transplanting. It can work in high efficiency and good quality comparing with the traditional manual work. The lower density transplanting path includes endeffector leaving from original point, grasping health seedlings from high density to lower density trays one by one, and going back to the start at last. The distances of transplanting path were decided by seedlings grasping order. Traversing search algorithm consumed large calculation to plan this transplanting path which does not meet the real time requirement. In this paper, four schemes of fixed sequences were optimized by using the greedy algorithm separately, and eight schemes were formed totally. The path planning methods were used in the sparse and dense trays to verify the effectiveness of the greedy algorithm scheme. Comparing with the longest mean value of fixed sequence schemes for high density trays path planning, optimal scheme of GAS3 could get a better result with more than 10.6% amplitude optimization. The average calculation time of the optimization scheme was 0.84s. Significance test showed the increase of vacancy holes reduced the effectiveness of length shorten. As a whole, the greedy algorithm scheme optimizes the lower density transplanting path, meets the realtime work requirement, and improves the transplanting work efficiency.

Abstract:Localization is a key problem of mobile robot in the field for robot navigation and control, which directly affects the accuracy. A new relative localization method of pointpoint scan matching for the mobile robot was proposed based on laser range finder to achieve the matching of complex environment information under the continuous state by using the displacement theory of Fourier transform and Fourier-Mellin invariant of similarity transformation. This method is inspired by the image matching and curve matching domain, which is based on Fourier-Mellin transform method. Firstly, environmental information was obtained in different continuous time of the robot; the previous state was set as a reference scan and the latter state was set as the current scan. The mathematical model of relative positioning parameter was established. Then, the dimension was reduced. The 1D Fourier-Mellin was used three times continuously to get the rotational and translational increment. Thirdly, the comparative experiment was carried out with a featurefeature method based on the extracted corner features. Finally, the mobile robot path line was surveyed under an indoor environment and the laser data were collected for simulating track circuit diagram which were compared with the real conditions of track circuit. The experimental results further demonstrated the effectiveness, superiority and adaptability of the proposed method. It is no need to extract features from environment and it also has high antinoise and low computational lost. 

Abstract:The interaction of soiltillage tool plays a pivotal role in analysis and optimization of the tillage process. The dynamic behavior of soil needs to be developed primarily when studying the soiltillage tool interaction. The simulation of soilrotary blade interaction using distinct element method (DEM) and indoor soil bin experiment were conducted to provide a better understanding of the soil movement. Firstly, DEM model of soilrotary blade interaction was established. Secondly, comparison of experimental results and simulation results were done, positions before and after tillage of surface soil particle were used as soil displacement in simulation, and tracer method was employed to measure soil displacement in experiment. Then, the movement of soil which belongs to different positions was analyzed. The results showed that soil forward and side displacement in experiment increased with increasing rotational speed of blade, the forward displacement was larger than the side displacement. The displacement of shallow soil was the largest, and then middle soil and deep soil had the minimum displacement. The closer the soil to the rotational point was, the larger the forward and side displacement of soil were. For the particles in tillage scope, the percent of particles which moved to the opposite direction were 26.2%, 72.1% and 48.4% for shallow soil, middle soil and deep soil, respectively. Most soil particles moved backward in horizontal direction during tillage process. The direction of side force and side displacement depended on the situation that the soil particle lay in the left or right side of the lengthwise edge axis. If the soil lay in the left side of the lengthwise edge axis, the side displacement was towards the left and vice versa. The soil particle moved downward with the rotary blade at the beginning of soil cutting, and later it slipped from the border of blade and being tossed up. The average error of soil displacement between simulation results and experimental results was 24.9% for soil forward displacement while 15.3% for soil side displacement. The paper studied the macro and meso movement of soil particles during rotary tillage, which is helpful to understand the interaction between rotary blade and soil and develop the mechanism of rotavator design and optimization.

Abstract:At present, most of the work that taking trays out from the rice nursery seedling planter is completed one by one manually, which is laborintensive and inefficient. There are some tray stackers can realize the function of automatic stacking, but the existing devices are only suitable for hard trays. Aiming at above problems, the automatic tray stacking device of rice precision seeding for nursing seedlings pipeline, suitable for both hard and soft trays, was developed to improve productivity and reduce labor intensity. According to the characteristics of common hard tray, the pallet of soft tray was developed for stacking. Besides, the transportation mechanism was designed through analyzing the conveying model. Based on the programmable logic controller（PLC）, the trays were detected by a proximity switch of the control system, and the tray stacking mechanism was controlled to lift and drop the trays to achieved the tray stacking automatically（2~4 trays per stack is available）. In addition, the cover plate of the soil antifalling mechanism was controlled to lift after stacking and finally the device can effectively prevent the soil falling out of the tray in the process of stacking that lead to seeds exposed. For detecting the performance of automatic tray stacking device, the orthogonal experiment was carried out which regarded stacking success rate and seeds exposed rate as indexes and regarded the lifting speed of tray stacking mechanism, cover plate installation conditions and productivity as factors. Orthogonal experiment results showed that the lifting speed had more influence on success rate while the lifting speed and cover plate installation conditions had more influence on seeds exposed rate. When the lifting speed was 0.15m/s, the cover plate installing with pneumatic cylinder and the productivity was 600~800 trays per hour, the stacking success rate of hard tray and soft tray was 100% and 99%~100% respectively while the seeds exposed rate was 0.28% and 0.60% respectively. The automatic tray stacking device can effectively raise productivity and reduce labor intensity, and the experimental indexes meet the using requirements of rice precision seedling.

Abstract:In order to reduce pesticide waste of pesticide spraying in the field and alleviate the pollution to the soil, a smarttargeting spraying system on boom sprayer was designed, aiming at satisfying the requirements of spraying for large row spacing and plant spacing. The system was mounted on the common spray boom spraying machine in field, and an ultrasonic ranging sensor, which was corresponding to row and furrow, was set according to a certain distance along spray bar direction. The distance between spray bar and canopy and the distance between spray bar and the bottom of furrow were measured in real time. The vibration noise generated by the uneven furrow and the boom vibration was eliminated by utilizing the signal amplitude modulation. According to the features such as plant height, canopy diameter and canopy height, etc., the amplitude modulated data was carried out in pattern analysis to recognize targets and realize smarttargeting. The equipment test was carried out on the tobacco plant in the field, which has 30cm plant height and 15piece leaves or so. The test results illustrate that, this smarttargeting spraying system has a valuable reference for the design of other target spraying systems. Comparing with continuous spray, the boom sprayer smarttargeting spraying system could save pesticides about 30% and 20% for the gap rate of 39.2% and 31.6%, respectively. Therefore, this smart-targeting spraying system is well performed in the target spraying operation in the fields where the plant space is beyond 15cm and could significantly improve the agricultural economic efficiency.

Abstract:The waterfertilizer mixing process with an opentank in the fertigation system was analyzed by a simplified dynamic mixing process in this paper. Then a variable universe fuzzyPI control strategy was proposed which aimed at the characteristics of nonlinearity, pure hysteresis, time degeneration and uncertainty in the control system. A set of stretching factors with proportional exponential function was used to modify the universe of the fuzzy controller on line for improving its adjustability. Considering the influence of varied rotational irrigation schedule, a cofuzzy controller with onedimensional was proposed to regulate the reference value of integral coefficient of PI controller, through monitoring the system flow change on line. And the correction value of control parameters of PI controller were regulated by the variable universe fuzzy controller. In order to verify the validity and advantage of proposed control algorithm(VFPI), four experiments with different recipes and three experiments with different rotational irrigation situations that compared to the traditional PI controller were carried out, while the testing platform of fertigation control system was established. The contrast testing results demonstrate that the proposed VFPI control strategy has better adjustability than the traditional PI control method. When the recipe contents or rotational irrigation situations varied, the VFPI controller has smaller overshoot, better dynamic quality and reliability than the traditional PI controller.

Abstract:Spray fertilizer needle is the executive component of pricking hole mechanism, which is working on the soil directly, so its construction feature will affect the fertilization quality. In order to improve the operation quality, a new type spray fertilizer needle with double oblique hole was designed and its dynamics characters were studied. On the dynamics testing system bench, taking forward speed of soil tank vehicle and rotation speed of planet carrier as experimental factors, and the reaction of soil particles to spray fertilizer needle as indicator, the reaction force of soil particles to spray fertilizer needle during pricking hole was determined. Result shows that, the tensile stress of needle was decreased with the increasing forward speed and rotation speed, which was in the range of 19.944~25.936N. Bending force was increased with the increasing forward speed and rotation speed, which was in the range of 8.62~75.32N. The rotation speed has a significant effect on the reaction of spray fertilizer needle. According to the test results, the rotation speed of planet carrier with the range of 100~120r/min could improve the work efficiency and ensure normal work of pricking hole mechanism.

Abstract:To further improve the efficiency of vibratory harvesting on tree fruit and reduce the mechanical damage on tree body, a hypothesis about ideal fruit tree excitation pattern was put forward based on the working principle of vibratory harvesting mechanism. The influence of different kinds of displacement patterns on vibratory fruit harvesting was simulated based on finite element software (ANSYS). According to the simulation results, a vibratory fruit harvesting mechanism was designed based on planetary gear train to generate epitrochoid trajectory. Then, its characteristics and working principle were analyzed and its kinematics model was established to derive the equations of vibratory displacement and acceleration amplitude. By meeting the requirement of displacement and acceleration amplitude, main parameters of the epitrochoid mechanism were optimized based on the parameterguided optimization algorithm. A prototype of vibratory harvesting mechanism for fruit tree was manufactured and its trajectory was recorded by highspeed photography system. Trajectories of experiment, theoretical analysis and virtual simulation were consistent, which verified the design of this harvesting mechanism. A dynamic response test of one fruit tree sample was carried out in lab. Statistics results on the mean value and standard deviation of the maximum synthesized acceleration of the test points on the tree sample confirmed that the epitrochoid mechanism could stimulated the fruit tree effectively.

Abstract:In recent years, the nutrition and health values of blueberry are comprehensively accepted by experts and scholars, which make the planting area increase year by year. But it is still in short supply in the international market. Blueberry picking machinery research and technology is mature in aboard, especially in the United States, blueberry picking machine has a big market. In China, the planting technology of blueberry has matured, the cultivation area expands gradually and has begun to be a big amount, but the harvesting technology for blueberry is still manual picking techniques, whose efficiency is low. When the maturity time of blueberry is very short, mechanization picking for blueberry is a potential trend. For the rapid development current situation of China’s blueberry industry in recent years, a highbush blueberry picking machine was researched and developed. The picking machine design requirements and working principle were analyzed, and the picking frequency and inertial force of blueberries branches were estimated. Based on the design requirements of picking machine design, the hinge four rod mechanism was designed by a given travel speedratio approach. And the double rocker mechanism was designed by using graphic method and the picking system of machine was applied. The experiment results show that the machine picking efficiency is 829g/min, which is 12.67 times higher than manual picking efficiency, the fruit damage rate is 8.3%, the picking rate is 96.9%, and the immature fruit abscission rate is 9.7%, which verified the quality and efficiency of the proposed blueberry picking machine.

Abstract:In order to improve the performance of a seed corn detasseling machine, a roller type tasselremoval component and a performance testing apparatus for the same were provided. Onefactor and multi-factor orthogonal experiments were carried out with plant feeding speed, air-charged pressure, central distances between the rollers, roller revolving speed, and roller’s inclination angle as factors and with the tassel removal rate, and the leaf loss rate as evaluation indicators. The experiments show that central distances between the rollers and the roller’s inclination angle have significant influences on the tassel removal rate and the influences on the leaf loss rate of the respective factors decrease in the order as below, central distances between the rollers, aircharged pressure, roller’s inclination angle, and roller revolving speed. The following parameter combination demonstrates the optimal performance of the roller type tassel-removal component. The central distance between the rollers is 254mm, the aircharged pressure is 50kPa, the roller’s inclination angle is 30°, and the roller revolving speed is 450r/min. Under the above settings, when the plant feeding speed is set as 5km/h, the tassel removal rate is up to 97.8%, and the leaf loss rate is up to 24.4%; and when the plant feeding speed is set as 3～6km/h, the average tassel removal rate is up to 97.8% and the average leaf loss rate is up to 27.4% which meet the agronomic requirements.

Abstract:In order to improve the work quality of carrot harvester, roots and stems cutting device of carrot was designed based on statistical analysis of physical parameters of carrot. This device consists of leveler, gripping delivery mechanism, double disc blade cutting device and upper gripping delivery mechanism. Force analysis of double disc blade cutting device was done by the means of graphic analysis, the request of stems being cut was obtained by the experiment; rotate speed of disc blade was determined at 312~325r/min by analyzing the operation velocity. The working parameters of disc blade were calculated according to the agricultural requirements and the objective of low energy consumption. Two kinds of blades were designed, and cutting rate and root damage rate were chosen as the experiment indicators. The contrast test was done and the result showed that operation performance of the ordinary disc blade and blade with serrated edge was approximate. Both of above blade’s cutting rates were more than 90%, and the root damage rate was less than 2%. Taking the economy into consideration, field experiment was done with the ordinary blade, the result showed that when the device worked at the speed of 1.34m/s, the net rate was 98.3%, cutting rate was 90.6%, root damage rate was 1.8% and the total losing rate was 3.5% which met the requirement of carrot harvester.

Abstract:In order to reduce the loss of peanut caused by peanut plants stacking and throwing during two-stage peanut harvester working, a spring-finger cylinder pickup was designed by analyzing spring-finger swing and movement rule of a sliding spring-finger cylinder pickup in four processes of picking, lifting, pulling, and null swing with peanut harvest agronomic and plant physical and mechanical characteristics parameters, including spring-finger, crank, slide, shield, etc. which were optimized and designed optimally by NSGA-II for minimum shield radius. Equations of cam slide centerline locus were designed by using spring-finger swing characteristic. Cam slide centerline locus was obtained and smoothed by using Matlab and cubic non-uniform B-spline. The end displacement locus of the spring-finger was obtained by using ADAMS. The quintic polynomial was used in null swing station with spring-finger swing simulation analysis. The experiments of prototype working and collecting peanut plants indicate that, the phenomenon of peanut plants stacking and throwing was disappeared; the optimal working parameters of springfinger cylinder pickup were obtained by using response surface method: the forward speed was 48.0m/min, cylinder rotating speed was 53.1r/min, and height above around was -7.4mm. The collecting rate and the loss rate were 98.9% and 2.5% respectively under peanut plant moisture content of 15%~17% in two-stage harvest.

Abstract:By improving spatial transmission project of Dknotter, a type of knotter driven by double gear-discs was presented. Spatial transmission of driving ropeholder was arranged on another side of knotter stand. It simplifies a set of angle relation of spatial crossed axle on the imported knotter stand as angle relation of plane intersecting axle, reduces processing difficulty of the knotter stand, overcomes the difficult design and manufacture problem of spatial crossed bevel gear profile on the imported knotter, and is easy to be manufactured in large quantities. By adjusting the transmission ratio between worm and helical gear to 1∶3, original ropeholding plate with four notches was changed into ropeholding plate with three notches. The structure model of the knotter driven by double geardiscs was built up after the motion sequences of driving ropeholder, knotter jaw and knife arm were matched. The contrast test of knotting motion with the imported knotter shown that the improvement of spatial transmission project of the knotter driven by double geardiscs is reasonable, moreover, the motion sequence matches design of ropeholder, and knotter jaw and knife arm are right. The ropeholding and ropecutting motions are even better than those of the imported knotter, and the rope is directly got into the notch of ropeholding plate and cut off in the middle of the knife. The knotting tests operated on indoor bench showed that the knotting rate of the knotter driven by double geardiscs may reach 100%. Further field tests of bundling straw will be executed to investigate the knotting rate and the reliability of knotter driven by double geardiscs.

Abstract:Aiming at the problem that the power consumption of straw countersfield is difficult to test, this paper proposes a virtual test platform evaluation countersfield set power consumption method. Firstly, the dynamic model of straw countersfield was established. The boundary conditions and loads were set up. The virtual simulation of power consumption in straw countersfield was carried out with the buried depth of 120mm and 90mm, forward speed of 3km/h and 5km/h, rotation speed of 260r/min and 230r/min, respectively. Then the field power test system was built and the relative errors were 9.06% and 8.02% respectively by comparing the simulation data. The accuracy and feasibility of the proposed method were verified. Finally, 18 conditions (three buried depths, two forward speeds, and three rotating speeds) were selected to carry out the simulation. The results show that, with a certain buried depth, the straw countersfield set power consumption has an increasing linear relationship with forward speed and rotation speed. With a certain buried depth and forward speed, the lowest power consumption appeared at the rotation speed of 230r/min. Moreover, with a larger buried depth and forward speed, the effect of rotation speed on the power consumption is obvious.

Abstract:In the course of circular mould straw briquetting, the entrance of the circular mould is worn very serious due to sliding friction between straw pellet and the circular mould. With a vertical circular mould consisted of H module as the research object, this paper put forward a rolling entrance structure which is made of bearings and roller, and the structure is stationary fitted in round holes of two wings up and down at the waist position of H module closed the feed side. When straw pellet was pressured into the mould hole between adjacent rollers, rolling friction coefficient between rollers and straw pellet was reduced smaller than sliding friction coefficient between the original mould and straw pellet, the purpose of weakening the module wear was achieved. At first, wear rule of the original circular mould before improvement was analyzed by the FEM. The geometric model of the original circular mould consisted of H modules was established in accordance with 9JY2000 straw briquetting machine of a factory, high and wide of the mould hole are 33mm×32mm. Under conditions that elasticity modulus of straw was 8.1GPa, plastic relation of straw was Euler stress and Almansi strain, sliding friction coefficient between the circular mould and straw was 0.4, hardness of the circular mould was HRC55, rotation speed of pressure rollers was 30r/min, temperature was room temperature, straw briquetting was simulated by means of the Archard wear model. The result showed that normal pressure at the front edge of the H module waist was larger, 45MPa, and wear rates of this edge was 0.11μm/s. The second, wear rule of the circular mould of rolling entrance structure after improvement was analyzed by the FEM. Under conditions that diameter of the roller was Φ35mm, friction coefficient between the roller and bearing bush was 0.01, the model of the circular mould of rolling entrance structure was established and simulated by the FEM. The result showed that rollers laid a single direction intermittent rotation, the maximum angular velocity was 0.05rad/s; the maximum normal pressure was 23.7MPa, and the wear rate of this point was 0.01μm/s, which was far less than wear rate before improvement. At last, according to field experiments, the circular mould of rolling entrance structure can play the function of reducing wear and prolong the life of the circular mould.

Abstract:The integrated virtual testing system for tractor economy performance was designed, which aimed to meet the research requirements on the tractor fuel and energy saving technology, the power assembly design optimization, the agricultural operation standard determination, etc. Firstly, the hardware lectotype was determined based on the requirement analysis of tractor fuel consumption test. Then the test system based on NI cRIO controller was designed, which can complete the synchronous acquisition of instantaneous fuel consumption, fuel consumption per 100 km, velocity, driving path and engine working state parameters, etc. Consequently, the virtual software design of the test system was described in detail, including FPGA software, realtime software and PC data acquisition and analysis software. The X4 encoding programming technology was used to acquire the double TTL signals output by the fuel flowmeter, and the resolution ration for the effective impulse signal could be increased by four times. By means of the determination for fuel forward and backward moving, and the FPGA precisely timing capture for the jump or down edge of the TTL signal, the test accuracy for the instantaneous fuel consumption could be improved effectively. In order to analyze the engine work state, the CAN and K line from OBD interface were connected to the test system and the relative programming was made to acquire the engine output torque, the engine speed, etc. Finally, according to the comparison tests and field tests, the samples and data processing methods employed in the system for instantaneous fuel consumption were accurate and in realtime. Besides, the whole system function and reliability were also validated. The study of this paper provides an effective means to comprehensively evaluate and analyze the tractor economy performance.

Abstract:Those works of aquaculture, such as cleaning aquatic weed, feeding, and increasing the oxygen content in the water body and so on were tedious and burdensome. Chinas aging population led to labor tensions, high labor costs. In order to solve the employment problem of the aquaculture industry, reduce labor costs and improve labor efficiency, a universal water surface operating platform for the aquaculture industryunmanned navigation paddlewheel vehicle was proposed. The characteristics of the boat motion were analyzed; the method for calculating the paddlewheel driving force was gave according to the hydrodynamic theory and Newtons law, which overcame larger error by using the old original formula. The hydrodynamic equations of the paddlewheel vehicle were constructed, based on the characteristics of paddle vehicle movement and Fossen’s theory of ship motion model, and then was simulated by computer and experimented by experimental boat. With an installed highprecision GPS equipments and communications equipment on the experimental boat, sailing trajectory data was measured and recorded. Boat was set at speed of 0.4m/s, the left paddle of 60r/min, and the right paddle of 40r/min conditions, turning diameter measured by the GPS device was 3.2m. The results of simulation and experiment show that the paddlewheel could make the boat realize ahead and turning motion and the boat has better mobility at low speed, the paddlewheel vehicle is very suitable for aquaculture. Digital model provided a way for the study of paddlewheel vehicle motion control and system design, optimization in the future.

Abstract:In order to study the influence of different straw mulching modes and surface tillage adjustment measures on environmental regulation of root zone of the northeast black soil, field experiments were conducted under five tillage practices of surface tillage with straw mulching (STS), notillage with straw mulching (NTR)，surface tillage with straw mulching and compaction (SCTS), notillage with straw mulching and compaction (NCTR) and conventional tillage (contrast TC) for analyzing time and space dynamic change of soil moisture, heat, nutrient and physical properties by straw mode and surface tillage measures. The results showed that: straw mulching with surface tillage could improve soil physical structure on seeding stage and harvest stage, the soil bulk density of 0~50cm soil layer was reduced from 1.32% to 4.06% and 0.81% to 1.64%,the soil organic matter and available nutrients of 0~30cm soil layer were increased from 4.89% to 20.74%,1.94% to 40.37%,7.18% to 30.26% and 1.22% to 28.09%，the soil moisture of 0~70cm soil layer was increased from 6.83% to 1384%，the daily soil temperature difference at seeding stage of 0~10cm soil layer was reduced from 0.5℃ to 2.8℃ than that of comparison TC, so the effect of surface soil layer was higher than that of the bottom layer. Under the experimental condition, SCTS has advantages on regulation soil environment of root zone for high efficient and sustainable comprehensive evaluation. Research results provide reference basis for promoting implementation of covering cultivation measures on the northeast black earth area.

Abstract:Lowtempreature plasma （LTP） treatment of seed before sowing is the largest application of mordern physical method in agricultural production. As a conductor, plasma is known as the four states of matter, belongs to the areas of physical discipline. Lowtemperature plasma stimulation plays an important role in optimizing crops in terms of activation of endogenous substances in the seeds rejuvenation, promotion of plant grown, protection against disease, and the maximization of yield. Plasma seed processing technology is the use of high energy aggregation on treating crop seeds within 20 s. The LTP plasma stimulation could improve seed germination and seedling growth. This technology was applied practically and works well now. In this paper, the effects of different intensities of LTP on Alfalfa seeds were investigated on the fourth and twentieth days after treated. The vigor, germination rate, germination index, wintering ability, returning green stage, plant height, tillers and pod growth were compared for treated and untreated seeds. The result shows that LTP could improve alfalfa seeds germination and seedling growth，and advance the reviving stage. There is a great value of using and spreading on production.

Abstract:In order to quickly and accurately measure the soil total nitrogen content(STNC), 72 soil samples were collected from Beijing City for chemical measurements and spectral analysis. By correlation analysis of the actual measured nitrogen content with spectral data which wavelength is 350~2500nm, the most relevant characteristic wave bands were selected to build the STNC estimation models. To establish accurate and optimized predictive model of STNC, the spectral reflectance and absorbance were converted into firstorder differential and secondorder differential. The results showed that both spectral reflectance and absorbance had a low correlation with STNC, so they could not be used to build prediction model. Their correlations were improved by transforming them to the firstorder differential and the secondorder differential. In various transformation of reflectance, the secondorder differential and the secondorder differential of absorbance were the most relational with STNC. The maximum absolute values of correlation coefficient were 0.868 and 0.846. The most relevant characteristic bands were 425~527nm， 819nm， 1390~1391nm and 2200~2219nm. STNC models were built through linear regression and multivariate stepwise regression. The reciprocal logarithm secondorder differential model based on multivariate stepwise regression was the optimal model among the 10 prediction models established in this article. This conclusion proved that it is feasible to use multivariate stepwise method for predicting STNC. The R2 of the optimal model was 0.829, statistics value was 86.377 and the RMSE was 0.104. This model can be used to predict the STNC of clay loam soil in Beijing City.

Abstract:The main factor of hindering straw fermentation is lignocellulose hydrolysis due to the shielding effect of lignin. The shielding effect of lignin stops the extracellular enzymes of microorganisms getting in touch with cellulose leads to hydrolysis of acid fermentation process slowly. So the key to solving the bottleneck of the anaerobic fermentation process of straw is to damage the lignin structure in the hydrolysis stage and promote the contact of hydrolytic bacteria with the cellulose and hemicellulose. The reproductive capacity of aerobic microorganism is much higher than that of anaerobic microorganism and the initial cleavage of lignin requires the molecular oxygen. So the aerobic and anaerobic twophase fermentation process was put forward in order to improve the degradation rate of lignocellulose. The fermentation process was divided into aerobic hydrolysis fermentation and anaerobic methane fermentation in order to degrade lignocellulose of rice straw which was carried out at 37℃. Hydrolysis of acid fermentation tank was not sealed by stirring gas supply or non gas supply. The results showed that lignin structure of rice straw was damaged by aerobic and anaerobic twophase fermentation and higher lignin degradation rate was obtained. Lignin degradation rate of the stirring gas group was 4.57%, while degradation rate of lignin was only 0.13% at the end of the singlephase anaerobic fermentation. The highest biogas yield of TS was about 411.19mL/g at the stirring gas group 30% higher than the singlephase anaerobic fermentation. Therefore aerobic and anaerobic twophase fermentation process could effectively degrade lignin and increase biogas yield of TS.

Abstract:Release and reactions of elements in biomass ash of rice straw, corn cob, palm kernel shell and wheat straw enzymatic hydrolysis residue were investigated by experiments of biomass ash sintering and melting. The ash was considered to be sintering as the Mohs’ scale of hardness was up to 3, which would block the burner or gasifier. The ash in this paper was prepared at 600℃, and put into the tubular furnace of 700~1200℃ in order to evaluate the temperature of sintering and melting. The ash was put into the tubular furnace at the sintering temperature for 5~30min, which showed the process of sintering. According to the analysis of ash by XRF and XRD, volatilization of KCl became obvious after 800℃. Parts of K and Na stayed in the ash, forming alkali feldspars in the reactions with SiO2 and Al2O3. Volatilization of alkali metals would cause an increase of melting temperature in TG-DSC and fusion test, which is different from the character of coal ash. The method of evaluating the coal ash sintering temperature is unreliable for the ash of biomass. Different elements in the ash have different characteristics of melting and reactions, which decides the sintering temperature. The sintering temperature decreases with more Al, Ca, K, Na, S or less Mg, Fe, P, while the influence of Si is weak. As the main composition of biomass ash is SiO2, the sintering temperature can be estimated to be 0.9 times of sintering temperature. Using the data of four kinds of biomass ash in the experiment, the linear regression fits for the sintering temperature against the mass percentage of ash components was obtained with R2 of 0.967 and error of 25.6℃ for the sintering temperature range of 950~1200℃.

Abstract:The quadratic orthogonal rotation regression combination design was employed in this study to determine effects of poultry manure amount, biochar dosage and C/N ratio on biocharmediated mesophilic anaerobic digestion of poultry manure. These three factors were then subjected to response surface methodology to obtain optimum parameters for methane production. The results showed that specific cumulative methane production (SCMP) could be obviously increased by adding appropriate amount of biochar during anaerobic digestion of poultry manure. SCMP was increased as biochar dosage increased from 2.5% to 5.0%, but was significantly decreased with the further increase of biochar dosage up to 7.5% (P<0.05). Lower poultry manure amount could result in higher SCMP. The effect of C/N ratio on SCMP showed the same trend with biochar dosage, namely an initial increase up to certain level and followed by decreasing change. The highest SCMP (288mL/g) was observed with biochar dosage of 5.0%, poultry manure amount of 17.83g and C/N ratio of 25. The developed mathematical regression model here showed a good fit with the experimental data. Moreover, the model predicted that the maximum SCMP could be obtained with biochar dosage of 4.97%, poultry manure amount of 14.35g and C/N ratio of 22.02.

Abstract:Aiming at solving the shortcomings of low dilution ratio, short residence time and bad portability of the existing dilution channel sampler, the flue gas dilution sampler for biomass fixed combustion source was developed by using the principle of multistage dilution and jet, according to numbers of atmospheric particulates and characteristics of mass distribution in high temperature flue gas. The sampler consists of five parts: sampling gun, first level dilution system, second level dilution system, clean air making system, impact sampling device and display control system. The proposed sampler has good airtightness, high dilution ratio, stable heat preservation performance and good control precision. The biomass fixed combustion source of flue gas dilution sampler was applied on the wood molding testing. Test results show that the proposed device could simulate the dilution and condensation process of combustion source flue gas which emissions into the atmosphere environment with dilution ratio of 30 and residence time of 90s. The atmospheric particulates in eight different particle sizes were obtained, in which the mass of particle size of 0.4~1.1μm took 55.5%~68.1% of the total mass of atmospheric particulates. The study found that the proposed sampler has a good effect on the atmospheric particulates with diameter less than 1.1μm.

Abstract:Dairy systems are the important greenhouse gases emissions source, in which manure management is one of the three major GHG emission sources. Most researches focused on the effects of external conditions, such as additives, composting materials, composting height, stacking mode, and the frequency of pile up on the greenhouse gas emissions of livestock manure composting process, while a few studies focused on the impact of diet on greenhouse gas emissions frommanure. Different diets were fed to dairy cows during different lactating period, which results in different physical and chemical properties of manure. The objective of the study was to quantify the greenhouse gas emissions and varies of carbon and nitrogen of manure from cows during different lactating periods. Fresh manure from cows during different lactating periods was collected and piled up naturally. Emissions of CO2, CH4 and N2O were measured by using static chamberGC technique, at the same time, the content of TOC, TN, NH+4N and NO-3N were measured. The results showed that there was difference in content of TOC, TN and C/N between manure from different lactating period cows (high group, middle group and low group). At the beginning of piling, manure from high group contained the highest TOC and TN, followed by middle group, then low group, in opposite for the ration of TOC to TN. These differences resulted in accumulative emissions of greenhouse gas differently. The highest accumulative emissions of CH4 and N2O were measured from high cow group, followed by middle group and then low group. The total greenhouse gas emission from low group was significantly low than that from middle group and high group. CO2 accounted for more than half of the total greenhouse gas emission, CH4 and N2O contributed 20%~21% and 17%~21% to the total emissions, respectively. Accumulative emission of N2ON was significantly positive correlation with TN content, in opposite with the ratio of TOC to TN. Accumulative emission of CH4C, CO2C and CO2C+CH4C had no significant correlation with TOC content and the ratio of TOC to TN.

Abstract:Wine ageing is an important process to produce high-quality wines. Traditionally, wines are aged in oak barrel ageing systems. Oak barrel has important roles on the aroma component, color, stability and clarification of wines, however, due to several disadvantages of barrel ageing technology, including the high cost of oak barrel, the long ageing time required and the large space taken up by barrels, which seriously affect and restrict the production capacity and economic benefit of the enterprise. Therefore, on the premise of guarantee the quality of wine, using the artificial ageing technology to shorten the aging time, improve wine quality and reduce production costs become a hot area of research in recent years. This paper reviews recent developments of the artificial ageing technologies of wine, such as treating the wine with microoxygenation, oak products, high hydrostatic pressure, magnetic field, irradiation, etc. The impacts of each technology on wine quality during ageing were analyzed, and comparisons among these artificial ageing technologies were made. Furthermore, several strategies to produce highquality wines in a short ageing period were also proposed.

Abstract:During high pressure processing (HPP), the work of compression always causes the food materials to undergo a reversible adiabatic temperature increase. This phenomenon results in nonuniform temperature distribution during processing. The compression heating can also influence the inactivation of bacteria, spore and enzyme. But knowledge in this filed is still very limited. In this study, adiabatic compression heating characteristics of food materials during HPP was investigated using a specially designed experimental setup. Selected liquid and solid food materials were studied at different pressure levels (100~400MPa) and different initial temperatures (15~45℃). At 25℃ initial temperature, ethanol had the highest δ (adiabatic temperature increase up to 12.8℃/(100MPa)) of the samples examined, and δ value was decreased with increasing pressure. Compared to high water content foods(26~4.0℃/(100MPa)), fats and oils showed higher δ values (7.3~10.7℃/(100MPa)), which were also decreased with increasing pressure. For high water content foods, δ values was increased with increasing initial temperature, but fats and oils had little or no effect of initial temperature. An empirical equation was established to predict the adiabatic temperature increase value during HPP at different pressure levels and different initial temperatures for food materials. The thirdorder polynomial was used to fit the δ values of orange juice, honey, whole milk, semiskimmed milk, soybean oil, beef and ethanol. The regression coefficients of these equations were all above 0.97. This study provides useful information for the optimization of high pressure processing.

Abstract:The objective of this work was to quantify the crosscontamination of Listeria monocytogenes from raw to cooked food through different material cutting boards. Transferring experiments were performed to mimic the food preparation process. The marinated pig tongue sample was inoculated with 1mL initial bacterial suspension then put there about 15min before splitting. The cucumber was split on the cutting board at the same position of tongue. Meanwhile, transfer rates from marinated pig tongue to cutting boards and cutting boards to cucumber under various common four scenarios were also determined. Building exposure assessment model of food in different operating modes in the kitchen simulation environment and comparing incidence rate after consumers eating contaminated food dealing with different cutting boards. The results showed that each set of transfer rates proved to be changing in a certain range, and transfer rates of different material cutting boards under the same scenarios varied significantly over experiments （P<0.05). The exposure assessment model of foodborne pathogens from meats to readytoeat vegetables showed the crosscontamination with some potential risks to consumers. And the risk of wood cutting board was higher significantly than that of the other two kinds of material cutting boards.

Abstract:This research aims to explore the drying behaviors of the saturated frozen porous media during atmospheric freeze drying, which is based on the refrigeration of vortex tube. The experimental study to analyze heat and mass transfer in drying of apples was undertaken numerically. In the numerical part, a twodimensional geometric model of atmospheric freeze drying conditions was constructed by using the software of ANSYS ICEM CFD, and the model was divided into meshes for the computational domain which can make the numerical simulation results clearer. The changes of moisture ratio and core temperature of frozen material was obtained through iterative solution, which was adopted the methods of porous jump model and the finitevolume method(FVM), under different conditions of inlet velocity and radiation temperature. The optimal combination of the parameters was got by means of analyzing the changes of mass and heat transfer of drying sample during different conditions. According to the simulation results of optimal parameters, heat and mass transfer for material can be investigated from velocity field, temperature field, pressure field and the migration of drying area in porous media under different time. In the experimental part, apple slices was applied to drying process. As expected, while drying condition was carried out at a wind speed of 2.5m/s on the inlet and an irrational temperature of 283.15K, experimental values are fitted with the simulated values. The correlation analysis was carried out between experimental and simulated value of material moisture ratio and core temperature through the SPSS-21 analysis software, the R2 value was 0.564 and 0.982 respectively. Such a methodology could be reasonable for studying of freeze drying.

Abstract:For exploring the feasibility of litchi browning identification based on physicochemical indexes, the browning indexes, chromatic aberration a*, b* and L* value, total soluble solids content (TSS) and hard degree of litchi in storing under three common used environments (room temperature environment, refrigerator environment and controlled atmosphere environment) were measured. Under the above three environments, browning indexes of stored litchi were increased with the increasing storing time. However, the increasing speed of stored litchi under room temperature environment was the most fast, the refrigerator environment was the second, and the controlled atmosphere environment was the third. Physicochemical indexes, including chromatic aberration a*, b*, L* value, and hard degree, were decreased with the increasing browning indexes. But the change of TSS was not obvious with the increasing browning index. The accuracy of linear discriminant analysis (LDA) for brown degree identification of stored litchi under room temperature environment, refrigerator environment and controlled atmosphere environment were 96.67%, 100% and 100%, respectively. However, the litchi samples of 4th browning index were similar with those of 5th browning index under both refrigerator environment and controlled atmosphere environment, which may cause confusion in practical classification and identification. Thus, LDA can identify the litchi samples of 1st, the 2nd, the 3rd, the 4th~5th browning index effectively. The results of partial least squares regression (PLSR) for stored litchi under above three environments show that fitting coefficients (R2) of predicted value and actual value were 0.85 and 0.90, respectively, which proves that litchi could be predicted by using the same model but under different environments. This experiment has revealed the relationships among browning indexes, physicochemical indexes and storing time, which proves the feasibility of physicochemical indexes for litchi’s browning identification, and provides a reference for fruit’s browning identification and value estimation.

Abstract:To solve the problems of difficulties in detecting the slightly green potatoes placed randomly, two detection methods were compared based on the semitransmission and reflection hyperspectral imaging technologies and then a more optimal detection method was determined. 225 potatoes samples were selected, including 122 normal samples and 103 green samples. Semitransmission and reflection hyperspectral imaging technologies were used to extract the RGB, HSV and Lab color information from the image; the isometric mapping (Isomap), the maximum variance unfolding (MVU) and the Laplacian feature mapping (LE) were utilized to reduce the dimension of image information. Semitransmission and reflection hyperspectral imaging technologies were used to extract the average spectrum from the spectral region of interest; the linearity preserving projection (LPP), the local tangent space alignment (LTSA) and the locally linear coordination(LLC) were utilized to reduce the dimension of spectral information. The deep belief networks (DBN) model which is a kind of deep learning approach was developed based on the image and spectrums of different hyperspectral imaging ways. The multisource information fusion technology was used to optimize the model with a high detection accuracy and different detection models were built based on different ways of imaging or the fusion of image and spectrum. The results show that the fusion model, which is developed based on the semitransmission hyperspectral imaging and the reflection hyperspectral imaging, is the best option. Its detection rate can reach 100% in both the calibration and the validation. Nondistractive detecting of the slightly green potatoes can be realized with this fusion model.

Abstract:Leaf area index (LAI) is one of the important parameters to describe the corn canopy structure. PROSAIL model is a mechanism model for retriving LAI, which can express canopy situation more truly. But the leaf angle distribution function used in PROSAIL model assumed that the leaf angle distribution is constant during whole crop growth period, and it cant reflect the actual leaf angle distribution of the corn plant. This paper studied the extracting method of the maize LAI based on the PROSAIL model, using GF-1 images and terrestrial LiDAR data. In order to get the leaf angle distribution of maize, the point cloud of maize was separated into small leaf units through voxel method, and then the surface was matched according to the point cloud in each voxel. The accurate leaf angle distribution function was acquired from statistics data of each leaf unit angle. Combining with the ellipsoid distribution function, the accurate leaf angle distribution function was got, which is used to optimize the PROSAIL model. In this research, the maize canopy LAI was retrived in Farm No.852, Heilongjiang Province, through traditional PROSAIL model and optimized PROSAIL model respectively. The main conclusion is as follows: all of the two methods of inversion of LAI have a good correlation with measured LAI as coefficient is 0.5576 and 0.8583 respectively, which proved that this model is credibly. But the result of inversed LAI based on unimproved model is low. After optimized model with TLS data, the inversion of LAI estimation accuracy was improved from 26.53% to 96.23%.Therefore, it can greatly improve the accuracy of LAI inversion by introducing the TLS point cloud data to improve crops leaf angle distribution function in PROSAIL model.

Abstract:With the rapid development of unmanned aerial vehicle（UAV）, it is widely used in the field remote sensing which is different from the satellite remote sensing, and has many advantages such as more convenient, lower cost, and shorter revisit cycle. However, effective information cannot be extracted from the multispectral images of UAV easily because of the highresolution multiband redundant data which can increase the complexity of data processing and consume a lot of computational resources. Therefore, the purpose of this research is to study the optimum bands combination which can be extracted by multispectral image. Manas’s riverside in Shihezi, Xinjiang was selected as research area. Fixedwing UAV equipped with Micro MCA12 Snap was used to obtain highresolution multispectral images. Based on this system, a method was proposed to select the optimum bands combination for topographical objects classification. First, the standard deviation and correlation coefficient of the multispectral image’s gray value were analyzed; the original bands combinations were got with the OIF method. Then, the most informative spectral feature bands and texture feature bands were determined respectively by using variety methods, such as vegetation and water index, principal component analysis, and GLCM. Finally, the original bands combination, spectral feature bands and texture feature bands were combined to obtain the final result. According to the analysis, bands 1,6,11, NDVI, NDWI and the mean parameter of GLCM combination of Micro MCA12 Snap multispectral sensors were selected as the optimum bands combination for topographical objects classification. After the selection of the bands combination, unsupervised classification and supervised classification methods were used to verify the classification accuracy with the optimum bands combination respectively. The classification accuracy with IsoData of ROI (region of interest) was increased from 83.57% to 89.80%, when it comes to SVM, the accuracy was increased from 95.58% to 99.76%. In addition, the study also provides effective reference for the selection of optimum bands combination with UAV multispectral images.

Abstract:Manilensis is one of the major pests in China. A method for recognizing different ages of manilensis was presented based on Kmeans clustering and principal component analysis (PCA) with selected feature wavelength. The hyperspectral images in the range of 400~1000nm of manilensis back at differnet ages among adult, 5age, 4age and 3age were collected and the average spectral information of target region on manilensis back with the size of 15 pixel×15 pixel was extracted. A wavelength secleting method with combined PCA algorithm and Kmeans clustering (K-PCA) was proposed. The model for identifying manilensis ages was built by using Fisher algorithm and then compared with K-PCA algorithm and successive projections algorithm (SPA). The experiment results showed that the K-PCA algorithm needed fewer wavelengths but with the higher accuracy of 98.25%. The final feature wavelengths of K-PCA algorithm were 468nm, 555nm, 635nm, 710nm, 729nm, 750nm, 786nm and 899nm. The proposed method provides a certain technology support for manilensis monitoring and precention.

Abstract:An onsite field experiment, which includes five nitrogen fertilizer application rate treatments, four phosphorus fertilizer application rate treatments and two summer maize cultivars treatments, was conducted at agricultural experimental station of Northwest A&F University during 2011—2014. Summer maize canopy spectral reflectance and aboveground dry matter accumulation (ADMA) were measured at the huge bellbottom stage, silking stage, filling stage and maturity stage of summer maize. 21 canopy vegetation indexes of hyperspectral remote sensing in 2011 and 2013 were chosen to establish liner, logarithmic, quadratic and exponential regression relationship between ADMA and canopy spectral parameters for each cultivar. Different regression models were applied to establish the relationship between spectrum vegetation indexes and summer maize ADMA. Three models with high coefficients and F values at each growth stage were chosen to verify root mean square error and relative error with data of canopy spectral reflectance and ADMA in 2012 and 2014 separately. The smallest root mean square error and relative error models were chosen as the best models for estimation ADMA of maize. The results show that, at the huge bellbottom stage, filling stage and maturity stage of maize, spectrum vegetation indexes for the best fitting regression relationship models with ADMA were GNDVI, PSSRc, NDVI4 and DI. These models could be used as the best models for the estimation of summer maize aboveground ADMA.

Abstract:Vegetation temperature condition index (VTCI) combines the main parameters of normalized difference vegetation index (NDVI) and land surface temperature (LST), and is applicable to a more accurate monitoring of droughts in the Guanzhong Plain, Shaanxi, China. VTCI also provides a scientific basis for drought relief and crop yield estimation by using remotely sensed data. This study chose Guanzhong Plain as the study area, and was to combine the remote sensed VTCI and simulated soil surface moisture by the CERES-Wheat (Crop environment resource synthesis for wheat) model to get a high regional yield estimation accuracy by using the fourdimensional variational (4D-VAR) data assimilation approach. The improved analytic hierarchy process, the entropy method and the joint the two weighting methods were used to establish winter wheat yield estimation models by using the monitored VTCI and the assimilated ones respectively. The optimal model for estimating winter wheat yields in the study area from 2008 to 2014 was selected, and the measured wheat yield of the year 2011 was used to validate the accuracies of the optimal model. The results showed that no matter at the sampling sites or at the regional scale, the assimilated VTCIs were all better able to respond the monitored VTCIs and the surface moisture data, and the texture of assimilated VTCI images was better and more consistent with the regional drought distribution. Compared the yield estimation models with the monitored VTCIs, the accuracies of the yield estimation models with the assimilated VTCIs were improved, and the correlation coefficients of the optimal yield estimation model with the weighted VTCIs of 0.784（P<0.001). The optimal yield estimation model was applied to estimate wheat yields in 29 counties of the Guanzhong Plain, and the results showed that except for the Pucheng County, the estimated yields’ relative errors of other 28 counties in Guanzhong Plain were less than 15%, and the errors were less than 10% in 16 counties of Guanzhong Plain. In general, the average relative error of the estimated yields was 8.68%, and the root mean square error was 4219kg/hm2, indicating the optimal yield estimation model had a better performance. The yearly estimated yields from 2008 to 2014 were in an increasing trend with fluctuation in Guanzhong Plain. For the spatial distribution of the yields, the yields were the highest in the central of Guanzhong Plain, and the yields in the west were higher than those in the east.

Abstract:Leaf area index (LAI) is an important parameter in crop growth monitoring and crop yield estimation. However, optical remote sensing cannot extract the structural information. Light detection and ranging (LIDAR) can provide accurate crop structural information, so LiDAR can make up the shortage of optical remote sensing. Therefore, the purpose of this research is to study the vertical structure information of crops which can be extracted by LiDAR, analyze the correlation of LiDAR vertical metrics and LAI of crop, and estimate LAI of the whole study area. First, the metrics were extracted based on LiDAR data, including mean height above ground of all first returns (Hmean), maximum height above ground of all first returns (Hmax), minimum height above ground of all first returns (Hmin), the percentiles of the canopy height distributions(H25th, H50th, H75th, H90th), laser penetration index (LPI), density of points, porosity and leaf angle. Then, Pearson correlation analysis was used to filter LiDAR metrics which are better related to LAI measured data. Last, regression analysis of selected sensitive parameters was carried out on setting up LiDAR-LAI estimation model, and the LAI estimated result of the whole study area was calculated. The result shows that correlation coefficient between estimated LAI and field measured LAI is 0.79, and RMSE is 0.47. It shows that crop canopy structure parameters extracted by LiDAR can be used to estimate the spatial continuous and large area of LAI of crops.

Abstract:In order to explore the influence of land use change and driving forces in the process of urban development, this paper took Shunyi District, Beijing as an example and analyzed the dynamic changes of land use types in the study area. Meanwhile,the direction and degree of the transformation of land use based on Markov model with three remote sensing images in 2000, 2005 and 2010 were analyzed. Combined with GIS analysis function, the influence of various land use driving forces on land use types was discussed, and the factors of land use transformation were standardized by using fuzzy calculation and intergrated by using weighted linear combination method. CA-Markov model was used to simulate the distribution of land use in 2010. The accuracy of the proposed simulation results obtained was as high as 81.41%, the Kappa index was 0.7769. The feasibility and accuracy of the proposed method were proved. Based on the patterns of land use in 2010, the land use status of the land in 2020 was predicted and land use changes from 2010 to 2020 were analyzed. In addition to grassland and forest, the area of cultivated land and water continues maintaining the trend of reducing, but the trend is slowing down. And construction land is still increasing. This study provides scientific support for the planning and decision making of land use in the present and future.

Abstract:In order to improve detection precision of crop phosphorus (P) nutrition level, in view of the problem that the present detection precision of crop phosphorus nutrition level based on spectral analysis is low and the spectral reflectance of phosphorus was influenced by both chlorophyll and anthocyanin, a phosphorus nutrition diagnosis strategy was proposed by fusing spectrum characteristics and physiological characteristics of tomato samples. With five levels (25%, 50%, 75%, 100% and 150%) of P nutrition stress samples cultivated by soilless cultivation mode as the research objects, reflectance spectra of different nutrient deficiency greenhouse tomato leaves was acquired by spectrum analyzer as well as the SPAD values of tomato leaves were obtained by SPAD-502. In addition, anthocyanin contents in leaves were determined. By using the spectral reflectance data under four characteristic wavelengths and physiological characteristics (anthocyanin content and SPAD value) as characteristic variables for tomato phosphorus nutrition diagnosis, the P nutrition diagnosis model was built based on least squares support vector machine (LS-SVM). An improved particle swarm optimization (IPSO)—adaptive inertial weight particle swarm optimization (AIWPSO) was designed to search the optimum values of SVM parameters for improving the search efficiency and avoiding getting lock in the local optimization. The proposed method with reflectance spectral and physiological characteristics (model 1) was compared with other three different models. For model 2, the method was same as the model 1 with the spectral features data only, model 3 was traditional LS-SVM which the optimum values of SVM parameters were obtained by cross validation of spectral and physiological characteristics data and model 4 was same as the model 3 with the spectral features data only. The results showed that the correlation coefficient and root mean square error of P were 0.9611 and 0.461, respectively, higher than those of other methods presented in the experiments. It can be concluded that the accuracy of P nutrition prediction model of tomato was improved by combing spectral characteristics with physiological features. The LS-SVM model with IPSO can acquire better parameters than traditional LS-SVM model based on cross validation. The combination of spectral and physiological characteristics data with the proposed algorithm was proved to be a powerful diagnosis tool for P nutrition status in tomato, and provided a new idea for the rapid detection of tomato P nutrient content.

Abstract:The red edge parameters of plants spectrum were used to estimate foliar chlorophyll for nitrogen content and leaf area. Among these parameters, the red edge position (REP) is the best one for diagnosing the growth state of tomato according to statistical analysis. The REP was defined by the wavelength of the maximum first derivative of the reflectance spectrum in the region (660nm to 780nm) of the red edge. The six algorithms could be used to extract the REP, including fourpoint interpolation, maximum first derivative, inverted Gaussian fitting, Lagrangian, linear extrapolation, and polynomial fitting. In order to achieve a rapid and accurate application for predicting the chlorophyll content of tomato with REP, this study systematically analyzed the quantitative relationships and statistical characters between REP on various algorithms and leaf chlorophyll status, and then the linear regression, logarithmic regression, power regression, exponential regression and quadratic polynomial regression were used to develop the prediction models of the chlorophyll content for each REP extraction algorithm. The result showed that the logarithmic model of the linear extrapolation had the best accuracy and reliability. The calibration R2c was 0.6186, the validation R2v was 0.7711 and the root mean squared error of validation set (RMSv) was 8.3596. The exponential model of the fourpoint interpolation could be obtained easily according to reflectance at 670nm, 700nm, 740nm and 780nm, the calibration R2c was 0.6217, validation R2v was 0.7666 and RMSEv was 8.5682. The predictive ability was good enough to develop a monitoring instrument of tomato chlorophyll content. 

Abstract:Due to the limitation of the nodes energy and computation ability in wireless visual sensor network (WVSN), the high complexity of traditional video coding in encoder is difficult to meet the requirement of practical application. Distributed source coding (DSC) can fully exploit the source statistics at the decoder to reduce the computational burden at the encoder. DSC provides a new way for video compression of orchard because it can effectively solve the problem of limited resources of sensor node in WVSN. Distributed video coding (DVC) is based on DSC, but it is a lossy compression coding technique. It suggests that under ideal conditions, the same rate distortion performance can be achieved as traditional video codecs. In practice however, there is still a significant performance gap between the two coding architectures. In order to improve the performance of DVC, a block adaptive DVC architecture was proposed according to the strong spatial and temporal correlation of the orchard video. It selected the coding pattern in accordance with the correlation of video content. WZ blocks were encoded with low density parity check (LDPC) code. For practical consideration of computational complexity and errorcorrection performance of the decoder, the jointbitplane LDPC decoding algorithm was used. Apple and grape orchard videos were tested and the experimental results show that the block adaptive DVC architecture can make the best use of the spatial and temporal correlation for compression coding. Compared with the traditional DVC, at the same quality of coding, it can save around 6%~10% and 9%~13% of the bit rate for apple video and grape video, respectively.

Abstract:Machine vision technology has been well developed and widely used to monitor crop growth and diagnosis the nitrogen status of crops. A system that combines machine vision technology and near ground remote sensing to monitor crop growth and nitrogen status was established. The system, which should be convenient, efficient, practical and widely applicable, could provide a new theoretical basis and technical support for crop monitoring. The objectives of this study were to calibrate a remote service system platform for monitoring cotton growth and nitrogen nutrient status. The platform involves machine vision technology, digital image recognition segmentation processing technology, agricultural internet of things technology, Web network information transmission service technology, and remote database management technology. In this study, the nitrogen nutrient status of cotton being realtime monitored by twoyear experiment data. Color images of cotton canopies were captured with a digital camera fitted with a chargedcoupled device (CCD) as an image sensor. An image analysis approach was developed to extract the feature parameters canopy cover of the images. The model described the relationship between the canopy cover and total nitrogen content of cotton aboveground. The results indicated that the best relationship between canopy cover and aboveground total nitrogen content had an R2 value of 0.978 and an RMSE value of 1479g/m2. The platform provides users with access to the cotton growth monitoring center (field monitoring), the network information service control center (server), the image analysis and data processing center, the diagnostic decisionmaking and evaluation center, and the user browsing center. Based on computer vision technology, this “one network, three server layers, and five centers” system can be used to remotely monitor cotton growth and nitrogen status. In conclusion, digital cameras have good potential as a nearground remote assessment tool for monitoring cotton growth and nitrogen status.

Abstract:For contactless measurement of pig body dimension andimprovement of pig welfare in the real farm, a pig body dimension detection system was developed based on machine vision technology. An algorithm based on depth image was initiated to obtain pig’s contour, because color or gray image are easily affected by various light and dirty on pig body. Firstly, two top view images were captured for each pig by using a stereo vision system. Depth image was obtained through stereo image matching. Depth background subtraction algorithm was used to get pig height data, and pig contour was calculated through binary height image. Then a corner extraction algorithm based on concave structure was optimized and simplified to extract four pig head and tail cut points. Then eight pig body dimension measurement key points were calculated, finally five body dimensions including body length, body width, body height, hip width and hip height were detected. Automatic software was developed which combines the algorithm above based on LabVIEW development environment. Threedimensional detection accuracy of the system was verified by using calibration board in lab, the relative error of detection were less than 1% within 2m object distance and view center region has the minimum error. Then the system was installed in a commercial farm for verification. 32 Landrace pigs’ body dimensions were measured three times manually and then the system snapped pig`s image for estimation. Each pig`s five body dimensions were detected three times. The result showed the detected values of body dimension had relative error of 2%, and absolute error of less than 2cm. The pig body detection system based on depth image overcomes the problem of light and dirty on pig, and it can be used to detect pig body dimension contactless in the real pig farm.

Abstract:In summer, the mixing flow fans (MMF) are usually used to reduce the heat stress in dairy cows. In order to improve the cooling effect of mixing flow fans (MMF) in summer open dairy house, numerical simulation and field experiment were adopted to optimize the performance of MMF, without changing the dimensions and blade shape. Totally 24 geometry models of MMF with diffusers of different angles (90°, 120°, 150° and 180°) and different lengths (150mm, 250mm, 350mm, 450mm, 550mm and 650mm) were established for CFD simulation, and the angles and lengths of diffuser were optimized by taking the fan performance, wind speed distribution in the distance of 0.5~1.0m from MMF axial and nonuniform coefficients as evaluation indexes. In this thesis, the diffuser angle 90° was taken as an example, the best diffuser length of the diffuser angle 90° was elected according to the fan rotation speed distribution and the diffuser effect of overall calculated filed. The analysis of other diffusers angles(120°, 150° and 180°) used the same methods. The angle and length of the diffusers (90°/450mm，120°/350mm，150°/250mm) were better to improve the MMF air flow and flow field uniformity, making use of analysis the jet length and average axial velocity. Finally, according to the simulation and experimental results, the 150°/250mm diffuser increased the wind quantity and efficiency ratio by 3.80% and 11% respectively, and led to greater axial velocity and better nonuniform coefficients. This improvement provides a theoretical basis for facility agriculture equipment while reducing production costs.

Abstract:The tree crown volume is one of the important parameters to estimate the biomass. In order to make an accurate measurement of the tree crown volume with nondestruction, this paper took 3D laser point cloud data, which were used as a data source, to calculate volumes of sample trees. The 3D laser point cloud data were randomly selected by six species, totally 30 trees. First of all, this paper extracted the point cloud data of tree crown volume from all points after matching, mosaic, denoising and compression etc. Secondly, it extracted the edge feature points from the tree crown through the programming algorithm. Finally, the crown volume was calculated by using the principle of irregular triangle net (TIN). In this paper, the edge feature points, extracted from the programming algorithm, can maintain the whole body of the crown. The algorithm can further remove the redundant data, shorten the construction time of TIN and improve the calculation efficiency. In addition, tree species also have certain representativeness. Because they included conifer and broadleaf trees, so the crowns not only have the crown body posture characteristic of conifers, but also have crown body posture characteristic of broadleaf trees. The results were as follows: the RMSE was 0.832, the average absolute error was 0.49, and the average relative error was 1.75%. Comparing with the artificial measurement results by selecting five sample trees randomly, the precision was relatively good. It can be seen that there are few gaps between the two results, of which the accuracy can meet the requirements of production.

Abstract:Nondestructive detection for wood is more difficult than that for other materials because of characteristics of wood itself. According to the characteristics like complex internal structure and wide density differences among different tree species, a fast algorithm of inverse projection coordinates was proposed. A wood nondestructive detection and CT imaging system can be structured on the basis of this algorithm. This system consists of an Xray emitter, an offset plate detector, a rotating carrier platform, a data acquisition and imaging software. Setting glued laminated timber and small logs as test objects, the feasibility of the algorithm was verified. Firstly, the projection data were collected and corrected, then the projection coordinates can be calculated according to the distance from the source to the center of rotation, and the filtering function was set up and used to calculate the convolution operation with projection data. The wood faultage image was reestablished at last. The result shows that this algorithm can shorten the image reconstruction time of CT system to less than 1s. Its image resolution can reach 0.052mm2, and it can also show the internal defects such as holes and cracks, and structural features like wood knots, rings, changes between early wood and late wood, which verify the validity of the algorithm applied to wood nondestructive testing and CT imaging system. This system provides a effective method for wood nondestructive detection.

Abstract:In farming region of Inner Mongolia, animal husbandry is evolving from the traditional style to the modern style, which means the largescale sheep breeding, intensive management and industrial development. However, the newly extensive stable breeding facilities are easily to make sheep suffer from respiratory disease. In the early stage, cough sound of sheep can be detected for early disease warning and health diagnosis. In this paper, taking Dorper sheep, which has been widely promoted in Inner Mongolia, for an example, cough sound signal of sheep was automatically collected and recognized by computer. Without increasing the dimension of sound signal feature parameters, an improved Mel frequency cepstrum coefficient (MFCC) was put forward. The experimental results demonstrated that the 14dimensional parameters combined with improved MFCC, shorttime energy and zero crossing rate were used in the hidden Markov model (HMM) cough sound recognition system, whose recognition rate, error recognition rate and total recognition rate reached 86.23%, 7.17% and 88.43% respectively. And the combination parameters can be reduced to nine dimensions using principal components analysis (PCA) method. Furthermore, the cough sound recognition system based on HMM was enhanced by a backpropagation (BP) neural network, and it’s recognition rate, error recognition rate and total recognition rate reached 92.54%, 5.37% and 95.04%， respectively. Therefore, the recognition results meet the requirement of the Dorper sheep cough sound recognition.

Abstract:Tree trunk diameter is one of the most important tree measuring factors in forest inventory. To quickly and accurately measure the tree trunk, electronic components were applied for tree trunk image recognition and measurement. Application of image processing technology in forest mensuration proposes a solution for accurately measuring trees, which makes nonprofessional technicians measure trees easily without experience. Images were taken by camera and processed by CMOS. The image was smoothed by Gaussian inverse filter after conversion from RGB to greyscale. Then edge was detected through nonmaximum suppression and double thresholds edge connection. Tree trunk automatic detection algorithm was developed on the base of the detecting image. The algorithm used a 4column window that represented a vertical segment to extract the vertical segments from the images above. The algorithm got rid of the vertical segment with over two successive 0 values, including vertical, horizontal and diagonal directions. The detected 0 value was searched from top to bottom. In addition, individual points in the window were removed. When all the vertical lines were abstracted, the two vertical lines with the maximum width were represented as the tree trunk. Tree trunk diameter was computed according to the relationship among focal length, object distance, image distance and pixel size. The image recognition results were validated by selecting different trees. Results showed that the image recognition precision was 96.9% and most data were conformed to the requirement of forest inventory. The forestry intelligence was explored and the digitizing components was used to realize the forestry intelligence.

Abstract:An innovative oxygen mass fraction estimation method for turbocharged diesel engine was described. Based on the dynamic model of turbocharged diesel engine with high pressure exhaust gas recirculation (EGR), the Luenberger observer of the intake and exhaust oxygen mass fraction was developed. By using the data acquired from the standard sensors equipped on the engine, the intake and exhaust oxygen mass fraction can be estimated by using the Luenberger observer. The convergence stability of the observer was proved through a Lyapunov analysis, the results show that the observer can meet the stability requirements. It can be used for estimating the intake and exhaust oxygen mass fraction. For various reasons, it is not suitable to install universal exhaust gas oxygen (UEGO) sensor on the intake manifold; the intake oxygen mass fraction needs to be obtained by other means. The calculated algorithm of the intake oxygen mass fraction was proposed and the method was verified by using the GTPower simulation data. The maximum error was less than 1.3%, the results show that the calculation method was able to accurately calculate the intake oxygen mass fraction. Finally, the test bench of the YC4E170-31 diesel engine was built. The exhaust oxygen fraction can be calculated by using the UEGO sensor which was installed at the exhaust manifold. The observer of the intake and exhaust oxygen mass fraction was verified against the experimental data and simulation data, the results show that the observer can accurately estimate the intake and exhaust oxygen mass fraction, and the estimation error was in a reasonable range, which laid a foundation for air path controller design based on intake and exhaust oxygen mass fraction.

Abstract:n order to reduce the technical requirements of car start to the driver and avoid the wrong operation that will shorten the life of parking brake system, an integrated electronic parking brake system, which has motor and transmission mechanism, was proposed. The driver can realize the vehicle parking through the button of parking brake system operation. The start working conditions of vehicle were analyzed and concluded in detail. At the same time, the resistance of vehicle start was calculated, which provides basis for the research of control strategy. The research on structure and working characteristics of integrated electronic parking brake was carried out and the feasibility of start assist control was analyzed. The real vehicle test verified the correctness of start control strategy of integrated electronic parking brake system, realized the assistant control of vehicle start, reduced the dependence of drivers technology to vehicle start and increased the life of parking brake system.

Abstract:Exechon parallel kinematic machine (PKM) has been applied to machining, assembling and aerospace industries due to its high rigidity and high dynamics. However, its rotational ability is comparatively weak. In order to improve the rotational ability of the Exechon PKM, this paper proposed an Exevariant PKM whose topology is a 2R-P-U&1R-P-S parallel mechanism. And the mechanical structure of the proposed PKM was designed. According to its structure features, Exevariant PKM was divided into several subsystems. By considering the compliances of joints and limb structures and using the substructure synthesis technique, an analytical stiffness model was developed for performance evaluation. The stiffness matrix of the platform was derived to demonstrate a positiondependency. The stiffness matrix of the Exevariant PKM at the extreme configuration was computed to show a coupling effect in the PKM’s stiffness characteristics. Deformation of the Exechon PKM under an external load was computed by ANSYS workbench, based on calculation errors between the finite element method and the proposed analytical method which were obtained to illustrate the high accuracy of the analytical model. The proposed methodology of stiffness modeling can also be applied to other overconstrained PKMs and can evaluate the global rigidity over workplace efficiently with minor revisions.

Abstract:The pump performance is directly affected by the dynamics performance of pistonslipper group. Since the timevarying direction and magnitude of centrifugal force of pistonslipper group, friction force of slipper swash plate pair, and the interaction force between piston and bush, etc., the conventional dynamics parameters analysis of pistonslipper group is merely limited to either at a certain fixed position or with some simplification assumptions, which are unbeneficial to the optimization design of pump and the prospective evaluation of pump performance. In order to dynamically evaluate the dynamics performance of pistonslipper group over the whole operating period, a novel simplified mathematic model neglecting the action of centrifugal force of pistonslipper group and friction force of slipper swash plate pair, and a novel elaborated mathematic model considering the effect of all the forces acting on the pistonslipper group were put forward, which both accord with the actual condition of line contact force between piston and cylinder bore, and further take the continuous variation of force acting position between piston and cylinder bore with the change of working conditions of pump into account. The novel mathematic models were verified by the experimental results and the simulated results by distribution parameter method based on commercial softwares. The application practice indicates that the proposed models can be used to dynamically evaluate the dynamics parameters of pistonslipper group over the whole operating period, and serve the dynamic optimization design of pump.

Abstract:The magnetorheological (MR) valve is a smart control mechanism that using the magnetorheologcial fluid as the working fluid. The advantages of regulating pressure drop and fast response time make it has a promising application prospects in the vibration attenuating system. In this paper, an annular type MR valve with a fluid flow resistance gap of 2.5mm was proposed; the working principle of the MR valve was expounded in detail. At the same time, the mathematical model of pressure drop was derived based on the Bingham model. The electromagnetic field model and fluid flow filed model were established using the finite element method (FEM) and computational fluid dynamics (CFD), respectively. The changes of the pressure drop under different applied currents were analyzed using both of simulation methods, and the simulation result of pressure drop in the FEM method was accorded with that in CFD method. The maximum pressure drop using the FEM method was 948kPa, while the maximum pressure drop using the CFD method was 1079kPa. Finally, the experimental test rig was set up to investigate the pressure drop of the proposed MR vale under different applied currents and different loading cases, the test results show that the maximum pressure drop is 662kPa at the applied current of 1.8A, and the pressure drop is independent of the loading cases. Furthermore, the experimental results were compared to the simulation results too, and they are accorded with each other to some extent. In a word, the relevant results can provide some guidance for the design of other types of MR valves.

Abstract:To study the power generation characteristics of elastomer under uniaxial tensile situation, the mathematical model of dielectric elastomers under uniaxial tensile was established based on Neo-Hooken model, and the corresponding simulation model was set up in Matlab/Simulink environment. The relationships among applied force, stretch rate, initial voltage, and power generation were studied by using the simulation model; the results were compared to the experimental results, and a good agreement was found. Both simulation and experiment results showed that the generating capacity of dielectric elastomer in the power generation process was increased as the applied force, stretch rate, and initial voltage increased. Simulation results were compared with test results, and the main reason was analyzed that the experimental results were lower than the simulation ones: internal resistance of DEG, systemic obstruction, voltage loss of electronic components, measurement error and so on. The experimental results and research conclusions provide a way for later period job of DEG generator, and this study provides the basis for a further study of the power generation by dielectric elastomers, which has good practical value.

Abstract:Position and orientation characteristics(POC) of parallel mechanism describes the relative motion properties between arbitrary two links of parallel mechanism. POC has close relationship with topological characteristics of parallel mechanism. Whereas, POC of general parallel mechanism cannot be obtained easily sometimes. So it is important for topological structural analysis or design to program the POC calculation. Some important concepts were analyzed systematically such as the topological polynomial expression, the orientation group and POC, etc. The aligning structures of limbs and pairs of parallel mechanism were expressed by the topological polynomial expression. The orientation group provides the orientation relationships shared by axes of all pairs and limbs of parallel mechanism. With the motion characteristics of movable platform of parallel mechanism considered, a conception of motion characteristic space was proposed. Based on the correlation among motion characteristic spaces, two elimination principles were constructed: serial elimination and parallel one. These elimination principles build the quotient relationships between topological polynomial expression and orientation group, supporting for iteration calculations with the POC of parallel mechanism and returned as the result. Based on the string description, POCs of some parallel mechanism were derived with symbolic fashion and the results validated the proposed method. The results of this paper lay some necessary theory and methodology foundations for the computer aided analysis of topological structural characteristics and prototype synthesis of parallel mechanism.

Abstract:Hydraulic pumps belong to high reliability and long life product, its reliability has a critical influence on the reliability and performance of whole machine. After a long accelerated life test, it may still be nonfailure for high reliability and long life products, which makes it difficult to assess reliability. Aiming at the limitation of the traditional reliability assessment techniques, the reliability of the hydraulic pumps shorttime test method was proposed, which based on performance degradation theory to predict the reliability and residual life of products. To establish residual life prediction model for hydraulic pumps, based on the volumetric efficiency data, the nonlinear leastsquare method was adopted to fit time series, simultaneously, the optimum path search algorithm was built to select the best degradation path. The consistency check of the data in prediction model and the stepstress reliability life test were done by using nonparametric statistical theory, and the overall sample life distribution function was constructed with Monte Carlo numerical simulation method. The results show that the simulation data of fault sample distribution are consistent with stepstress reliability life values. Comparing the test parameters curves of the shortterm test with stepstress accelerated life test, the correctness and feasibility of the shorttime test method are further verified.