Abstract:It has many difficulties in monitoring and detection accurately and optimal control in aquaculture because the targets are so special and environment is so sophisticated that contributes too many impact factors. Big data technology, as well as mathematical models are used to process and analyze the large scale of data producing in aquaculture industry and the useful results are presented to producers and decision makers in intuitive form, which is the fundamental way to solve the above problems. The research progress and development trend of the applications of big data technology in aquaculture were deeply discussed. Firstly, the overall architecture of applying big data technology in aquaculture was proposed and the data sources and data acquisition tools were listed. Then, several kinds of analysis techniques, which had been well applied to deal with the existing problems in aquaculture, were mainly summarized and the several current big data platforms and the services they provided for aquaculture were introduced. Finally, in view of solving the difficulties and challenges faced in the process of applying big data technologies in aquaculture, the research future in this field was proposed form the aspects of comprehensive awareness, intelligent analysis, automatic decision-making, and big data standard system construction of aquaculture. In the applications of big data technology in aquaculture, data is the basis and analysis is the core. The ultimate goal is to take advantage of big data technology to improve the comprehensive productivity and efficiency of aquaculture. In order to achieve it, the actual demands in aquaculture should be greatly concerned. In addition, data of the whole industry chain in aquaculture should be integrated and the basic theories and core key technologies should be studied intensively and thoroughly. In this way, the application of big data technology in aquaculture will be deeper and the integration of the two will be closer, which will support the complete transformation and upgrading of China aquaculture industry.

Abstract:Multi-rotor plant protection unmanned aerial vehicle (UAV) in sloping fields was usually operated at a height of 1.5~3m above the crops. The significance of the terrain following is that the height of the plant protection UAV above the crops do not change when the gradient of the terrain changes. The plant protection UAV needed to maintain a stable terrain following to ensure the safety of flight and spray uniformity. A terrain following method was proposed by using millimeter wave radar. The pre millimeter wave radar was used for slope judgment .When the slope was small, the height of the differential GPS and the height of the ground penetrating millimeter wave radar were filtered by Kalman filter, which can improve the accuracy. When the slope changed beyond the threshold,the height of the pre millimeter wave radar and ground penetrating millimeter wave radar were fused by multi-radar information fusion, which can improve the response speed. Then fuzzy PID algorithm was used to control the height of plant protection UAV. Through simulation and field flight test, the millimeter wave radar was accurate over the crops, and the height error of terrain following was less than 40cm. The results showed that the adaptability and the spray uniformity of the plant protection UAV in sloping fields were ensured. The research on terrain following laid a solid foundation for the automatic operation of the plant protection UAV under various terrains.

Abstract:In order to solve the shortcomings of traditional artificial spraying pesticides and more efficient prevention and treatment of diseases and pests, a pesticide spraying system based on sixteenrotor unmanned aerial vehicle (UAV) was designed. The sixteen-rotor UAV’s basic structure and attitude calculation method were explained. The whole system was full of 10kg, cruising speed can reach 5m/s, and the flight time was more than 10min. The traditional extended Kalman filter (EKF) attitude calculation method cannot meet the work requirements under the strong vibration condition of the large load UAV. The attitude angle calculation accuracy was not high and the attitude angle divergence was easily caused. A CPF-EKF algorithm based on 20 dimensional state quantity was proposed. The bias error of gyroscopes, accelerometers and magnetometers were added as the state quantity, which made the optimal estimation of the attitude angle of the three axes more accurate. Complementary filtering (CPF) was treated as an EKF detection module. When the EKF had the divergence trend, the EKF was reset, thus the EKF divergence was avoided simply and efficiently. Using actual flight data to verify the algorithm, the static experiment showed that the precision of the roll angle and the pitch angle of the algorithm were ±0.05°, the precision of the yaw angle was±0.2°. The dynamic experiment showed that the precision of the roll angle and the pitch angle of the algorithm were±0.1°, the precision of the yaw angle was±0.5°, and the algorithm had good real-time performance.

Abstract:Street tree continuous spray methods cause serious environmental pollution, however, the existing target spray technologies for tree are difficult to extend to complex urban environment. Aiming at the above problems, recognition method of street tree target was studied, which obtained the information of crown position and distance in real time and provided an accurate spraying basis for street tree toward-target spraying. The research results would improve the intelligent level of medical equipment for prevention and control of street tree and provide theoretical and technical support for street tree pest control, which had low injection, fine spraying, less pollution and high efficiency. Vehicle-borne 2D LiDAR was used to capture 3D point cloud data of street, and variable-scale grid index of point cloud was constructed to process point cloud data online and search neighborhood fast. Height, depth, density and covariance matrix features were extracted from spherical neighborhood of point cloud data, and an 11-dimensional feature vector was constructed. Distribution characteristics of features were analyzed and support vector machine algorithm based on the radial basis kernel function was used to fuse features and learn a point cloud classifier of crown. FIFO buffer was used to save point cloud frame sequences, and then street tree target can be recognized on-line. The classification error rate on the test set was less than 0.8%, with a detection rate more than 99.4% and a false alarm rate less than 0.9%. Four most discriminative features were selected, which were height mean, depth mean, height range and height variance.

Abstract:Aiming at the problem of weak wind power performance of straight gas-assisted nozzle, the effects of nozzle tail parameters on the flow wind power performance of new “tail first contraction and then expansion” pneumatic nozzle were studied with the combination of single point wind speed test and numerical simulation. The three dimensional numerical model was established for the pneumatic nozzle based on the Reynolds averaged N-S equation and realizable turbulence model, and the correctness and validity of computational fluid dynamics (CFD) model were also verified by the wind speed test. Secondly, the wind performance of two types of nozzles was compared by numerical calculation. The results showed that outlet average wind speed was 1.36 times of the straight nozzle when the total inlet pressure was 105600Pa and the static pressure was 105200Pa. In order to study the effect of the tail parameters (the retract length of the convergent section and the height of the expansion section) on the wind performance of new type nozzle, the agent mathematical models were established by the optimal Latin hypercube design and radial basis function neural network (RBFNN), thus greatly facilitating the automatic modeling and compensating for the large amount of calculation for CFD. The R2 variance of outlet flow and outlet average wind speed were 0.98354 and 0.98728, respectively, the agent mathematical model could be used for performance prediction and guiding the scientific configuration of structure parameters. The intelligent decision and optimization research of the influence factors were researched based on agent mathematical model. With the increase of the height of expansion and increase of retract length, the average wind speed at the outlet end showed a downward trend, while the flow rate showed a trend of first increase and then decrease. The air flow reached the maximum value of 0.0179kg/s when the height of the expansion section was 1.08mm and the retract length of contraction in convergent section was 5.39mm; the average wind speed reached the maximum value of 67.9m/s when the height of the expansion section was 0mm and the retract length of contraction in convergent section was 0mm. Multi-objective optimization was made, the optimal Pareto set solution of the wind performance parameters were obtained, which provided a diversified reference for optimization match design of pneumatic nozzle and orchard.

Abstract:In order to effectively cover target weeds, improve the precision of target spray and reduce liquid pesticide waste and ecological pollution, the target spray method based on two-degree-of-freedom manipulator was adopted to optimize the target spray performance of the weeding robot. The establishment of the liquid pesticide spray model of weeding robot was the key to improve the precision of the target spray. Under the premise of considering the wind disturbance, according to the dynamics equation of the droplet particle trajectory, combined with the manipulator link and the joint variable parameters, the model of droplet spray was established and the theoretical covering area was derived. Based on this, the influence of nozzle pose, vehicle velocity and wind speed on the covering area of liquid pesticide droplet was analyzed by computer numerical simulation, and coordinate reconstruction was carried out on the nozzle spray point. A small opening direct-current low-speed wind tunnel was built indoors and the liquid pesticide spray model validation tests were conducted. The actual droplet covering area was obtained by image processing technology, which was compared with the theoretical droplet covering area, the area centroid error range was 4.1~7.2mm, and the area matching error range was 9.1%~17.8%. The experimental results showed that the error of the theoretical covering area compared with the measured test results was small and had a high consistency with the test results. This research can be used as a reference for the construction to target spray equipment and technology of related robots.

Abstract:Owing to high center of mass, long and heavy spray beam, the high clearance self-propelled sprayer has a tendency to swing when it runs on the bumpy farmland. Especially the frequency of the excitation from ground is approximately the inherent frequency of the suspension, which will result in reduction of work quality or even endangering security of itself. So a scheme of an active pneumatic suspension controlled in due course was put forward to address the issue. But in practical control process of the active pneumatic suspension, several problems need to be taken into account simultaneously, including the nonlinearities existed in the air spring system, requirements about multivariable control of the acceleration and displacement as well as the constrained conditions for output force or suspension distance. Aiming at above problems, a vibration control scheme of joint controller with H∞ state-feedback control and time-frequency nonlinear control was established. Firstly, the optimal gain of state-feedback controller was solved under H∞ condition with constrains. With it the appropriately objective pressure of the air spring could be computed in each moment of the control process. Then, the time-frequency controller handled a proportional solenoid valve to enable the inner pressure of air spring to meet the objective pressure. Experiments were implemented to verify the control strategy based on a test-bench of active pneumatic suspension. Under the harmonic excitation of 1.3Hz which was the first order resonance frequency of the system, the maximum sprung mass acceleration of passive pneumatic suspension was about 8.5m/s2, that of the semi-active suspension was approximately 7m/s2, whereas that of the active suspension was decreased to 2.5m/s2. In whole control process, the displacement of suspension was controlled within the limitation and reverted to initial position after impacting. Besides, responses under the condition of road random excitation were also tested. All results showed the validation of the active vibration suppressed scheme as well as the vibration control method mentioned.

Abstract:In view of the deficiency of traditional method of controlling the consistency of maize seeding depth, the method for controlling the consistency of seeding depth based on the force feedback was carried out and the downforce control system for maize seeding unit was developed. The system consisted of hydraulic cylinder mounted on the parallel four bar linkage profiling mechanism in a seeding unit, hydraulic system, downforce sensor, controller and vehicle computer. According to the force sensor information and the downforce threshold, the controller calculated and output the control value to hydraulic valves. The hydraulic cylinder was drived by valves to adjust parallel four connecting rod profiling mechanism to make the depth wheels and the surface pressure within the set threshold interval, so as to ensure the consistency of seeding depth. The field tests showed that the average quality rate of seeding depth of mechanical control of downforce and electric control downforce were 77.04% and 90.37%, respectively, while the seeding depth criterion was （5.0±1.0）cm, and the average quality rate of sowing depth of electric control downforce was 13.33 percentage points higher than that of mechanical control. Nevertheless, when the seeding depth criterion was （5.0±0.5）cm, the corresponding seeding depth quality rate were 31.11% and 56.30%, respectively, and the average quality rate of sowing depth of electric control downforce was 25.19 percentage points higher than that of mechanical control. The test results showed that the downforce control system can greatly maintain seeding depth stability and improve seed depth uniformity.

Abstract:Based on programmable controller PLC, a kind of control system that can pick up a row of tray seedlings and alternately cast tray seedlings was designed, it can be used for self-designed automatic transplanting machine and solving the problem of high precision and difficult coordination of the automatic transplanting machine. In order to reduce the inner damage of seedlings, the control system detects the status of picking process by three travel switches I1, I2 and I3 to make the picking seedling claws gradually stretching in inserting process. Using the photoelectric sensor to detect the position and quantity of seedling cups, and obtain its motion displacement by incremental encoder, therefore, the seedling pot was shot at the best casting place by their combination. Using 20 d cucumber seedlings in 72-holes and 128-holes seedling trays respectively, the experiments were conducted to test picking and casting performance of the control system. The results showed that if the planting frequency was between 40 and 70 plants per minute, the success rate of picking and casting was more than 95%, with average value of 97.98%. As the increase of planting frequency, the success rate dropped but changed a little, which proved that the autonomous designed control system can be used in different seedling trays and planting frequencies, achieving the goal of high-efficiency transplanting.

Abstract:At present, there are few theoretical and analytical models of tapered fertilization disc in China, which cannot reach the ideal width, and the uniformity of throwing fertilization is poor. A model of the movement of fertilizer particles on a conical fertilizing disk and in air was established. Considering the influence of rotation of fertilizer particles in the whole movement process, the absolute velocity of fertilizer granules moving to the edge of the vane was analyzed, and the three-dimensional coordinate system which was thrown into the air from the edge of the vane was established. The law of movement of fertilizer particles to the air was analyzed. The main factors influencing the movement of fertilizer particles were obtained, and then the main influential factors that affected the throwing distance and throwing uniformity were obtained. These influencing factors involved the movement parameters and structural parameters, including vane length, vane inclination and disc speed. After determining these influencing factors, coefficient of variation was elected as test index, a static bench experiment was carried out by the orthogonal experiment plan, which was conducted in the Engineering College of Northeast Agricultural University in early October 2017. Static experiment referred to International Organization for Standardization (ISO) 5690 and American Society of Agricultural Engineers (ASAE) S341.2. Static test used two-dimensional collection matrix method. The collection matrix area consisted of 253 boxes, each collecting box had external dimensions of 20cm×20cm×10cm and its thickness was 4mm. The experimental results were obtained in data processing, the results showed that the influencing factors were all significant. When the length of the blade was 145mm, the inclination angle of the vane was 0°and the rotating speed of the disc was 1200r/min, the horizontal coefficient of variation of throwing was 5.80%, which met the requirements of throwing fertilizers. The research can improve the fertilization efficiency of potato and provide a theoretical reference for the design and optimization of potato manure spreader.

Abstract:Rice is one of the major food crops in China，and fertilization is an important operation links in the process of rice production, the traditional way of fertilizing rice is sprinkling the granular fertilizer on the soil surface by mechanical or manpower. This method has the problems of unreasonable fertilization, such as many operation steps, uncertain fertilization amount and uneven distribution, which directly affects the rice yield. The side deep fertilization technology for paddy field is mechanically transplanting granular fertilizer (base fertilizer and tillering fertilizer) quantitatively to the rice’s side position with a certain depth, which can reduce nitrogen fertilizer amount by 20%~30% and availably decrease pollution of freshwater resources compared with the traditional fertilization operation. It is a cultivation technique with high output, stable yield and low cost. As a core carrier for application of side depth fertilization technology, the side-depth fertilization device for paddy field has such problems as low uniform fertilization, poor stability of the device and blockage of fertilizer transmission pipelines. In view of the above problems, combined with the agronomic characteristics of side deep fertilization in the paddy field, the key components (fertilizer feeder and pneumatic conveying system) of the side-depth fertilization device for paddy field were designed and analyzed. Through kinematics and dynamics analyses, it was concluded that the bigger the rotation speed of the fertilizer wheel was, the better the uniformity of fertilizer application was. It was calculated that the theoretical limit value of the rotation speed of fertilizer wheel in the corner of the fertilizer wrap was 150r/min, and a pneumatic conveying system suitable for transporting granular fertilizer was designed. The quadratic regression orthogonal rotation combined design was used for the experiment, and the rotation speed of the fertilizer wheel, the forward speed of the device and the wind speed of the fan were taken as the influential factors. The fertilization average and coefficient of variation of fertilization uniformity were measured and analyzed for fertilization device through performance detection of JPS-12 type discharging seed test bench. Through the analysis of variance and response surface analysis by Design-Expert software, the mathematical model between influencing factors and response indexes was obtained, and the mathematical model was optimized and validated. The results showed that the coefficient of variation of fertilization uniformity was 28.25% under the condition that the rotation speed of the fertilizer wheel was 21.96r/min, the advancing speed of implement was 0.93m/s and the wind speed of fan was 22.93m/s, which could meet the minimum fertilization rate of 150kg/hm2 at the side deep fertilization of paddy field in cold region in Heilongjiang Province. The research provided a reference for the research and development of the side depth fertilization device for paddy field.

Abstract:Aiming at the problems that low working efficiency and energy loss of liquid fertilizer of distributor for deep-fertilization liquid fertilizer applicator，the differential-type bidirectional distribution device for fertilizer supply that matched pricking hole mechanism for oblique type was designed. In order to avoid the winding of connecting hoses between the differential-type bidirectional distribution device for fertilizer supply and pricking hole mechanism for oblique type, the mechanism transmission principle that consisted of double planetary gears and annular gear was employed, and the transmission ratio of differential-type bidirectional distribution device for fertilizer supply was obtained based on the movement characteristics of spray fertilizer needle hoses couler of pricking hole mechanism for oblique type;the space-cam of differential-type bidirectional distribution device for fertilizer supply was designed to meet the characteristic that spray fertilizer needle sprayed liquid fertilizer, and the structure parameters of device were obtained, i.e., the upon movement angle of space-cam was 31.8°, the down movement angle of space-cam was 25.6°, base circle radius of space-cam was 100mm and the maximum value of space-cam stroke was 6mm. The kinematics of double planetary gears was analyzed, and the motion trajectory equation of planetary gears was obtained. The performance experiment of differential-type bidirectional distribution device for fertilizer supply was done. The hose status was recorded between differential-type bidirectional distribution device for fertilizer supply and pricking hole mechanism for oblique type when the device worked at each time interval of 45°rotation, the connecting hoses that did not twine were verified;the pressure of hydraulic pump as the influence factor, the amounts of liquid fertilizer were measured per 5s at different levels, the flow velocity of injection needle and hydraulic pump outlet were obtained, the rule of energy loss, value of energy loss for the device and the higher efficiency to spray liquid fertilizer of the device were obtained.

Abstract:In order to simplify the structure of seeding monomer, improve the quality of planting, and meet the agricultural requirements of narrow row of soy closely planting on planter, a centralized precision seed-metering device was designed. The method of slipped seed absorbing and impacted seed cleaning of seed-metering device was expounded. Through the analysis of the movement of the seeds in filling area, the pressure range of seed metering device for seed sorption was determined. The speed of the drop seed relative to the drum and the number of the suction hole passing through were analyzed. The force analysis of the multi-degree-of-freedom seal structure was carried out to determine the structural parameters of the hinge joint of gas chamber. The high-speed camera technology was used to conduct experiment, repeated experiment of two factors was conducted in which the test indexes were qualified index, and the missing index, the multiple index and the experimental factors were air pressure and operating speed. The results of the experiment showed that when the air pressure of seed-metering device was increased from 3kPa to 4kPa and the operating speed was in the range of 4~12km/h, the qualified index showed a trend of declining with the increase of working speed. When the air pressure was increased from 5kPa to 7kPa and the operating speed was in the range of 4~12km/h, the qualified index showed a trend of declining after the growing with the increase of working speed. The missing index was in decline with the increase of pressure value and in rise with the increase of operating speed. The qualified index was more than 95% and the missing seeding index was less than 2%, while the air pressure was 5kPa and the operating speed was in the range of 4~12km/h. This seed-metering device could meet the seeding requirements well.

Abstract:In order to improve the sowing performance of vibrating small-amount rice sowing device, theoretical analysis and experimental research on the mechanism of the quantitative-seeds feeding mechanism and the vibration uniform-seeds mechanism were carried out respectively. Discrete elemental software EDEM was used to simulate the feeding process of quantitative-seeds feeding mechanism with or without vibration. Through the comparative analysis of the simulation process of the quantitative-seeds feeding mechanism, the periodic small amplitude vibrations of seed box vibrating plate could alleviate the rice seeds funnel flow and promote the diffusion flow, meanwhile made the distribution state of the seeds in the seed roller fluffier. The simulation results of the quantitative-seeds feeding test showed that the vibrating effect of the seed box vibrating plate could increase the seed frequency, and realize the quantitative and stable seeds feeding performance. The simulation experiment of seeding performance of nine kinds of grooved plates was carried out to study the effect of different kinds of grooved plates on the seeds flow velocity and sowing effect. The simulation results of sowing performance experiment showed that with the increase of the grooved plate’s angle, the flow velocity of seeds on the grooved plate was gradually decreased and tended to be stable. The V-90°, V-105°, V-120° and U1-shaped grooved plates were optimized to provide reference for the vibration uniform-seeds mechanism optimization test, and reduced the number of subsequent tests. Through the sowing performance tests, it was obtained that the best sowing performance was using the V-120° grooved, and the qualified index was 93.91% while hole index was 0.94% when sowing hybrid rice with 0.26MPa air pressure. The qualified index was 96.10% and the hole index was 0 when sowing conventional rice with 0.28MPa. The research provided a research basis for the research and development of rice precision sowing device.

Abstract:In the light of lower qualification rate of sowing depth and poorer quality of film edge covered with soil that the traditional potato combine seeders had, and according to characteristics of mechanized covering soil in the northwest dry farming areas and requirements of potato planting with mulching in Hexi Corridor, potato combined seeder machine with imitated terrain which had the integration of rotary tillage, sowing profiling ability of fertilizing, ridging, seeding, mulching and film edge covered soil was designed. To reduce impact on seeding depth in the process of wheel walking, using linkage principle the position of opener installed in the rack was calculated. In virtue of EDEM software parameters of chain structure were optimized with the simulation experiment of two factors and three levels, and the maximum diameter of chain was 77mm, and depth of one was 25.5mm. The amount of soil covered was calculated by relative motion to improve the quality of covering amount of soil. The height of the back end of the shovel was 70mm, and the velocity of the rotation angle of the blade was 4rad/s, the radius of the impeller was 230mm, increasing the breaking soil performance of the impeller. Test results showed that when the operation speed of overall unit was 0.69m/s, qualified index of throwing and covering soil on film edge was 88.6%, missed index was 5.3%, replay index was 6.1%, the planting depth qualified rate was 90.4%, seed spacing qualified index was 89.4%, which met the agricultural industry standard requirement. Angle between inter film soil and ground was 65.3°, which met the requirement of potato planting and mulching in the western corridor of Gansu.

Abstract:Vibrating sieve for corn cleaning is a vital component of corn harvester. To further improve the screening efficiency of corn threshed mixture on the screen，a new type of driving mechanism of vibrating screen for corn cleaning was designed, in which three translations and two rotations of the screen can be realized based on the plane reciprocation mechanism with only two translation. To obtain the motion laws and screening performance of the screen，the displacement equation of any point on the screen were derived by using the closed vector polygon method. The lengths of each drive rod were determined by using optimal design of the software Isight. The optimization objective was that the displacement of the screen in the rear would be minimum. The back amplitudes of the screen optimized was 15.4mm. Combining Matlab software，the results of numerical simulation showed that the motion of the mechanism was cyclical and not simply harmonic. Comparative experiment was conducted on the new type of driving mechanism and the plane reciprocation mechanism. Sieving rate of corn particles penetrated the sieve with high-speed camera was recorded，under the condition of different speeds of spindle and the mass of corn threshed mixture. In the experiments，the mass percentages of corn kernels，corn stalks，corncob and light mixture were 73.3%，17.6%，8.7% and 0.4%, respectively. The conclusion was drawn that the optimized speed of spindle was 260r/min when the maximum feed mass was 6kg/s. The corresponding sieving rate was increased by 5.75% and energy consumption was reduced by 16.1%. The superiority of this new organization was proven. The research result provided a theoretical basis for designing more reasonable cleaning mechanism to improve the production efficiency.

Abstract:A V-groove dialing round type guiding-seed device was designed to improve the uniformity and stability of planting and meet the requirements of precision planting. The overall structure and working principle of the precision guiding-seed device were illustrated and analyzed. The optimal design of structural parameters of key components was conducted, such as guiding curve, V-groove and dialing round. The interaction model of machinery and maize was established by using discrete element method. The scoop-type metering device was taken as the seeding object and EDEM software was employed to simulate the guiding-seed process. And then the dynamic behaviors of maize were researched under the working conditions. Orthogonal simulation experiments were carried out based on numerical simulation technology with forward speed, rotational speed, tangent angle as experimental factors and with qualified index and coefficient of variation as assessment consumption. Based on experimental data, a mathematical model was built, and the experimental factors were optimized by Design-Expert 6.0.10 software, the best combination was achieved. The simulation results showed that as the forward speed was 7.69km/h, rotational speed was 29.47r/min, tangent angle was 46.10°, and the qualified index was 92.05%, the coefficient of variation was 8.00%, which could meet the requirements of precision planting. On this basis, the high-speed photography experiment, comparison performance experiment and vibration adaptation experiment were carried out. The experimental results showed that the majority of grains were slipping in a steady state in the tube and few irregular impacts and tumbling. The V-groove dialing round type guiding-seed device had better adaptability to different maize grains which could be used in conjunction with scoop-type, pickup finger-type and air suction-type precision seed metering device. Its qualified index was similar to that of unguided tube, and coefficient of variation was higher than those of retractable plastic guide tube, curved guide tube and unguided tube. Under the normal operating conditions (vibration amplitude was 1~3mm, and vibration frequency was 1~4Hz), the vibration amplitude and frequency had little effect on the homogeneity of the guided parts.

Abstract:The present status of research and application of rice seedling trays was introduced, and the operation performance of the industrialization automatic seedling nursing production line after deformation due to long-term use or improper transportation was detailed. Regarding deformation of hard tray like blanket as the research object, a deformation measurement technology was put forward. Three indexes of deformation, such as rupture length, twist warp and bending deformation, were introduced into the study. According to the above results, the deformable seedlings were divided into four grades, mild, moderate, slightly severe and severely deformed seedlings, and the applicable criterions of four kinds of deformation seedling plates were standardized. In order to verify the reasonableness and feasibility of the grading evaluation of the deformed seedling tray, from the point of improving the mechanical reliability of precision seeding seedling production line, deformation seedling tray was selected in maximum for seedling nursing production line. The success rate of tray feeding and tray stacking and the seed exposed rate as the evaluation index, 2SJB-500 precision rice sowing seedling nursing production lines were used to test various deformed seedling trays’ seedling nursing performance. The test proved the evaluation accuracy of the grading of deformed seedling tray and revealed the relationship between the deformation of the seedling tray, the index of the deformation amount and the productivity. For the four types of deformed tray, the success rate of tray feeding and the success rate of tray stacking showed an obviously declined trend, the seed exposure rate showed an increased trend with the increase of productivity. The tray with mild deformation and moderate deformation had small deformation, the tray of mild deformation can keep going on using;for moderate deformed tray, if the flange or the bottom of the tray existed a little broken, it should be properly removed on the operation, which can be used for the seedling nursing production line in lower productivity;for slightly severe deformed tray, if there was a larger deformation index, it should be selectively removed on the operation. As for the tray edge with many broken areas, the large bottom crack, the serious twist degree in some seedling trays, it can be directly removed;for the severe deformed seedling tray, it should be directly removed on the operation, otherwise it would affect the final seedling nursing performance in the factory production line. The proposed technology of the deformation measurement in tray was simple and easy-to-operate for evaluating the deformation degree of tray intuitively and vividly. Meanwhile, this guideline provided a research basic for the automatic identification, detection and elimination system of deformed seedling trays in the subsequent seedling production lines.

Abstract:The construction of high standard farmland is of great significance to the development of modern agriculture, ensure food security and promote the sustainable development of rural areas. It is an important prerequisite for the construction of high standard farmland by scientifically and rationally delimiting the sequence of priority areas. Taking Zhuozhou City of Hebei Province as an example, from four aspects of cultivated land site conditions, infrastructure, spatial layout and ecological protection, an evaluation index system of high standard farmland construction condition was constructed. Using the analytic hierarchy process (AHP) to evaluate the indexes of each index and comprehensively evaluate the construction conditions of high standard farmland. The matter-element model was applied to calculate the comprehensive correlation degree of each evaluation condition. Through the factor combination method, the limits of limiting factors in each evaluation unit were found, the Zhuozhou high standard farmland construction priority area was finally divided into four grades. The results showed that the construction conditions of high standard farmland in Zhuozhou City was good as a whole, the proportion of the grade 1 of priority construction was 17.58%, the proportion of grade 2 area suitable for adjustment was 48.60%, the area ratio of grade 3 area in the key construction was 32.70%, and the area ratio of reserve regulation area was 1.12%. Grade 1 and grade 2 region showed obvious outward from the center of the diffusion trend and spatial distribution had a strong continuity, suitable for large-scale, high standard farmland construction. The grade 3 area was distributed in the west of Zhuozhou City, the level of restriction factors was high and the number was large, it was a difficult area to build, and the distribution of the grade 4 was less. The research results can provide reference for the reasonable delimit and result verification of high standard farmland construction priority area.

Abstract:The state explicitly fully carried out the work of stripping the plow layer soil of cultivated land under construction, but the current research is rare about plow layer to strip and the soil resource space configure methods and empirical research, which is difficult to support the configure of plow layer soil-stripping and reuse. Based on the analysis of the spatial distribution of stripped soil supply-demand and the priority of replying, the supply-demand circles was delineated by the village, the spatial configure scheme of soil stripping and reuse was optimized by linear programming, and Binyang County, Guangxi Province was chosen as research area. The results showed that the plow layer soil of Binyang theoretical strippable was 2.40×106m3, and the remediation demand was 1.85×107m3. The supply of plow layer soil was far less than the demand and distributed unevenly in space. Based on the principle of priority of covering benefit, the priorities of the reply area were determined, and the allocation plan of the stripping plow layer soil was put forward. According to the plan, 5.2352×104m3 soil would be used to urban and rural construction land reallocation projects, 1.446637×106m3 soil would be used to land reclamation and development projects, 3.32738×105m3 soil would be used to cropping system of the rotation of upland crop and rice projects, 1.042804×106m3 soil would be used to high standard basic farmland construction projects. Binyang County was divided into seven supply-demand circles by using the supply-demand circle and linear programming model. The stripped soil was gradually used from high to low according to the priority of replying, the weighted average distance was 5369m, the recovery benefit was good and the economic cost was acceptable. The village as a unit of supply-demand circles, linear programming optimization of soil-stripping space configure method can optimize the use of ways, and shorten the transport distance, thereby enhancing the benefit and efficiency and providing reference for the implementation of plow layer soil-stripping and reusing in other regions.

Abstract:Accurate estimation of arbor forest biomass is of great significance for the study of forest ecological function and carbon storage. Because of the spatial heterogeneity of the survey factors, the geographically weighted regression method can estimate the local regression of variables and show a good application advantage. Based on the survey data of carbon sinks in Zhejiang Province, taking the biomass of arbor forest (including aboveground and belowground biomass) as dependent variable and factors with high correlation with dependent variable as the explanatory variables, the biomass of arbor forest was estimated by using the geographically weighted regression and co-Kriging methods and compared the accuracy of the two estimation methods. The results showed that the accuracy of arbor forest biomass estimation model (R2adj was 0.8204, RMSE was 23.0215t/hm2) constructed by geographically weighted regression method was better than that of co-Kriging method (R2adj was 0.7263, RMSE was 28.0549t/hm2).The coefficient of variation (Cv was 0.6189) of the prediction value of biomass of arbor forest using geographically weighted regression method was higher than that of the co-Kriging method (Cv was 0.5854). Because of considering the local variation of the estimated variables, the geographically weighted regression method had better fitting results than co-Kriging method, and the prediction accuracy was high. This study can provide a reference for estimating the forest biomass and other forest parameters in a wide range of tree stands by using the geographically weighting regression method.

Abstract:In order to solve the problem of finding the fixed plot difficulty for continuous forest inventory, improve the efficiency and reduce the cost, a permanent sample plot marking device was designed based on the principle of remote control alarm and GNSS positioning. The marking device was composed of main program module, positioning decoding module, remote control alarm module, the data transmission module, the sample update information storage module, etc. FreeRTOS operating system was transplanted on Cortex-M3, and C++ was used to carry out most of the functions such as remote control, low frequency positioning etc. For the location of information data transmission, a sample API was developed on the WeChat platform by calling a Baidu map to realize the route planning for general mobile phone users. When the investigators load the APP for searching the plot in a certain area of the marker, the remote alarm would automatically start ringing. Then the location would be sent to the handset, which would help them to find the marker more quickly. Verified by experiments, the efficiency of the marking device was about 324% higher than that of the traditional sample plot. Meanwhile, the device can directly read and write the historical information and real-time monitoring data. It was showed that the equipment can solve problems such as marking device finding difficulties and no history inventory information. Therefore, it can be used and promoted in the permanent plot for continuous forest inventory in the future.

Abstract:In forest region, walking environment is hybrid space mixed road networks and open space. People usually have diverse wayfinding objectives. In order to compute optimal walking path and provide wayfinding decision support, an optimal walking path analysis method for forest region (OWPAM-FR) was proposed. Firstly, the concept of walkability was introduced to build comprehensive walkability raster (CWR). Walking experiment in forest region was divided into unwalkable area, walkable area and easy-to-walk area. The special optimal walking path analysis problem can be transformed into a general multi-objectives least-cost path analysis problem in walkable area and easy-to-walk area. Secondly, walking costs were divided into terrain costs, including horizontal distance, spatial distance, slope, time and energy, and feature costs, including land cover and cognitive load. Single walking costs were computed and weighted, which were combined with comprehensive walking costs. The multi-objectives problem can be simplified as the single objective problem. Thirdly, adjacency list was extended and queen’s pattern was used to establish adjacency relationships of raster cells based on CWR. Then the comprehensive walking costs were computed and the raster network model was successfully established. Dijkstra algorithm was used to compute the optimal walking path. The results showed that OWPAM-FR can effectively model walking environment of forest region mixed open space and road networks. At the same time, the proposed method was able to reduce path cost of multiple wayfinding objectives and emphasis on different main objectives. In addition, OWPAM-FR composed of modeled steps had a certain applicability, which could be extended to several types of optimal walking path analysis applications, such as forest tourism, disaster relief and field investigation.

Abstract:Accurate nitrogen (N) management is a promising strategy to improve crop N use efficiency. It is important to accurately estimate the state of wheat nitrogen by unmanned aerial vehicle (UAV) remote sensing. The experiment was arranged in science and technology yard base in Laoling City, Shandong Province. The eight-rotor UAV was used to carry a Mini-MCA multispectral camera and collect the wheat canopy spectral data about four key stages (returning green stage, elongation stage, booting stage and flowering stage) of growth and development in 2016. Meanwhile, winter wheat samples of biomass, nitrogen uptake and nitrogen nutrient index were collected and measured synchronously. Grain yield was measured in mature stage. In critical stages and whole stage of different vegetation, indexes and agronomy parameters regression analysis models were established to assess winter wheat nitrogen nutrition diagnostic potential based on UAV remote sensing image. The results showed that it had better estimation of winter wheat nitrogen index (R2 was 0.45~0.96) based on UAV remote sensing image and the decision coefficient was gradually increased with the elapse of growth period. And those in elongation stage, booting stage and flowering stage were similar and had better ability for yield estimation. DATT power function model was the most powerful to explain the wheat nitrogen nutrition index (R2 was 0.95) in flowering stage. Therefore, the platform for multiple UAV rotorcraft synchronization carrying multi-spectral camera had better nitrogen diagnosis potential for winter wheat and it can be used to guide the precise nitrogen fertilizer management.

Abstract:Spatial autocorrelation information is easily lost in the process of traditional texture information extraction methods of hyperspectral image，leading to low accuracy of vegetation classification. An improved scheme was put forward aiming at the shortcoming of existent methods to form a new classification algorithm (CHISCI) based on spatial autocorrelation information. Firstly, one kind of spatial autocorrelation information of hyperspectral image was extracted by domain transform filter of interpolated convolution（DTFOIC）. Secondly, another kind of spatial autocorrelation information was obtained by the same filter on dimensionality reduced hyperspectral data. Finally, the two kinds of spatial information were combined and then classified by SVM which was not sensitive to high-dimensional data, forming CHISCI classification algorithm of hyperspectral image by spatial autocorrelation information.The CHISCI classification method was implemented on the hyperspectral data of Indian Pines and Salinas Valley. The following results were obtained. In the first place, the overall accuracy (OA) of Indian Pines was 96.16% and the Salinas Valley was 98.67%, which were 12~16 percentage points higher than those of SVM and PCA-SVM, and 4~16 percentage points higher than those of SGB-SVM, SBL-SVM and SGD-SVM by spatial-spectral information, and 4~6 percentage points higher than that of EPF, and 2~3 percentage points higher than that of IFRF. Furthermore, the average accuracy (AA) and Kappa of the CHISCI were also increased substantially, showing very good performance in hyperspectral classification. In the second place, although the training samples were only 6% of Indian Pines and 1% of Salinas Valley, the OA of both can reach 96.16% and 98.67%, which can remove salt and pepper noise in the classification map obviously. When the training samples were reduced to 3% and 0.3%, the OA can be over 90% and 95%, respectively. The effectiveness of CHISCI was fully verified in the hyperspectral classification. In the last place, the classification of some methods for grapes_untrained and vinyard_untrained in Salinas Valley were bad. The reason was that the spectral reflectances of the two vegetables for all bands were very close. However, the classification for the two vegetables of CHISCI can still reach 98.38% and 99.17%. It was showed that the CHISCI had excellent performance on the vegetable classification with close spectra. The experiments showed that the CHISCI algorithm was better than original SVM with pure spectrum information, the dimensionality reduction-based methods, the spatial-spectral information-based methods, and the methods based on edge-preserving filtering and recursive filtering. With the spatial autocorrelation information extracted by the DTFOIC, the performance of the classification of hyperspectral image with CHISCI algorithm was greatly improved, and the effectiveness of CHISCI was fully verified in the classification of hyperspectral vegetables, especially of those with close spectra. The method can be applied to the field of crop growing, diseases and pests monitoring, accurate classification and identification. It would also have potential significance for precision agriculture and agricultural modernization.

Abstract:The dimensional and size information contained in the 3D point cloud of dairy cows are of great importance to the body evaluation, size measurement and health assessment. While capturing the point cloud of dairy cows from the aisle between the dairy farm and the milking parlor, the missing area on the point cloud happens frequently, which greatly affects the accuracy of the three-dimensional modeling of the dairy cows and the extraction of body size parameters. In order to fix the large missing area on the point cloud, a cubic B-spline curve based method was proposed to repair it. Firstly, the surrounding background was removed from the dairy cow’s point cloud acquired by Kinect v2. Then, the extracted dairy cow’s point clouds were sliced and projected along the x-axis direction of the point cloud coordinate system. In each slice points, some points were filled in the adjacent points with larger spacing. Finally, cubic B-spline curves were used for fitting the filled slice points. The optimal values of parameters h and L were analyzed in the experiment, and a total of 225 frames of 45 Holstein dairy cows’ point clouds were repaired by using the optimal values of parameters h and L. The results showed that the average frame approximation error was reduced by 26.7%, and the large missing area on the point clouds was repaired and the sparseness of point clouds was also improved. The proposed algorithm had better uniformity and approximation performance than the cubic B-spline method, which provided an effective method for repairing large missing point cloud area.

Abstract:Pig drinking behavior is closely related to pig’s physical condition and piggery environment. Recording such data continuously is beneficial to the pig industry. However, it is difficult to get the detailed drinking data of each pig manually. An automated method is expected. RFID is used to detect pig drinking behavior recently. But this approach invades pigs and the piggery needs to be equipped with auxiliary facilities. There is no such concern by using video monitoring. Therefore, using machine vision to recognize pig drinking behavior was proposed. Firstly, to distinguish pigs from the background, threshold segmentation was used to get a binary image, in which pixels belonged to pigs were assigned to 1 and others were assigned to 0. From the binary image, each pig’s centroid and angle were computed and used to decide whether a pig was static or not. Drinking behavior is likely to happen when a pig stays in the drinking zone. Secondly, occupation index was computed to determine if a static pig was closed to the drinking nipple. Drinking behavior could be preliminarily judged through this way. Thirdly, a pig head detector was implemented by using deep learning algorithm to accurately confirm the occurrence of pig drinking behavior. At last, to confirm which pig was performing the drinking behavior, a pig identification detector was implemented. Through the multistep judgment, pig drinking behavior can be recognized precisely. Experiment showed that the precision rate of the proposed algorithm in the video data set was 92.11%, which was suitable to aid managerial decision making in pig production.

Abstract:To determine the visual response effect of locust inspired by different light properties of blue light, and obtain the stimulating mechanism and the polarized light induction information for locust to manufacture locust induction light source, based on the investigated experiment of swarm locusts visual stimulation response to different blue light properties, the physical characteristics of light energy required by locusts phototaxis and polarotaxis response were analyzed to obtain the influencing factors of light wave information. The results showed that the polarization effect of linearly polarized blue light determined the vector sensitivity of locusts visual response degree and linear polarized illumination restricted locusts visual tendency intensity and visual aggregation effect, and the visual stimulation of linear polarized light quality formed by polarizer in the weaker blue light was better, while depolarized blue light intensity decided the visual stimulation of locusts visual tendency intensity and the visual sensitivity of locusts visual aggregation effect, polarization degree and E-vector illumination presented the interaction effect intensifying or inhibiting locusts sensitive response to depolarized blue light. Meanwhile, enhancing the linear polarized and depolarized illumination inhibited locusts visual aggregation effect for the stronger depolarized illumination, emerging vector sensitive response difference of polarized E-vector, the visual response degree of the weaker linear polarized light and depolarized 0° vector light was superior, and the coupling vertical streaks with polarized light were used to intensify the stimulation of polarized light information and lower the polarized light illumination optimizing polarized light induction information, which was relative to 100lx polarized light, incited the change of the sensitive E-vector, and its 120° vector sensitivity was stronger, but when illumination was 10lx, visual tendency intensity and visual aggregation effect of 330° depolarized light was optimal. Moreover, locusts visual tendency intensity and visual aggregation effect of depolarized light had positive and negative correlation with polarization degree along with visual stimulation information, and polarized light illumination respectively, and locust visual response effect on 10lx polarized light presented the change law of sine and cosine functions response to vector change, indicating locusts had E-vector polarization response pattern and vector function with the maximum activation of visual polarization nerve, and then the coupling effect of 30° and 330° of 10lx depolarized blue light and 100lx linear polarized light or 0° of 10lx depolarized blue light were utilized to improve locusts visual response effect effectively.

Abstract:To study the wind field pattern created by unmanned aerial vehicles (UAVs) in agricultural chemical applications, triggering the wind speed sensors distributed in crop canopy along the flight path simultaneously when the UAV passes over each of them is critical in capturing the instantaneous wind field data. However, in many cases the measurements were triggered manually by human vision which reduced the timeliness and validity of the data. The data acquisition triggering method was improved and automated for wind speed sensors by predicting the exact UAV flyover timing with accurate geo-location information from an onboard Beidou positioning system and the modeling of future flight status based on past flight data given that agricultural UAVs usually operate at low speed and low altitude without overload. Since the weed speed sensors used could only record data for five seconds, a flight status prediction model was developed to determine the triggering timing for data acquisition based on the consistency and stability of the flight direction, speed, and altitude within a certain period of time. Extensive field experiments were conducted, and the model predicted and wind speed sensor measured maximum wind speed data were compared. No significant difference was found between them at a 99% confidence interval with a P value of 0.956. With the improved triggering timing, the averaged maximum wind speed in X, Y, Z axes occurred at 3.036s, 2.427s and 3.145s, respectively, of the five-second logging period with standard deviations of 0.79s, 0.87s and 0.98s, respectively. The maximum wind speed, which corresponded to the wind speed when the UAV flew over each sensor, measured by the improved data acquisition system was ensured to be captured now within the five-second optimal logging period of the wind speed sensors by the improved aerial-and-ground-sensor cooperative sensing system.

Abstract:Land use of plain-hill-wetland blend area in Sanjiang Plain was changed significantly, resulting in the decline of groundwater level and shortage of water resources, while rare research was focused on revealing the effect of land use change on water resources, especially on the temporal and spatial distribution of water resources of surface water and ground water, wetland water and green water. A plain-hill-wetland blend area hydrological model was constructed based on distributed TOPMODEL and wetland flow kinematic model. The land use change and its impact on water resources in Naolihe River Basin was analyzed by using GIS and RS technology, combined with the geo information and spatial autocorrelation method. The results showed that the areas of grassland and woodland in the Naolihe River basin were changed little, while dry land area was decreased slightly according to the change of cultivated land area and dynamic degree distribution between 1990 and 2013;unused land and dry land with advantageous conditions for production was converted to paddy field in the central and northern areas of Naolihe River Basin;The influence of land use change on water resources declined in the order of withdraw water quantity, green water reserves, runoff flow, green water flow, and groundwater recharge;the evaporation capacity of paddy field was different in different rice growth periods, which led to the increase of green water flow, decrease of green water reserves, decrease of runoff flow, increase of groundwater recharge and increase of withdraw water quantity during May and June in Naolihe River Basin. The difference of these items was decreased gradually during July and August, and disappeared after August. Green water flow was increased, green water reserves and runoff flow were decreased, while groundwater recharge and withdraw water quantity were increased in paddy field.

Abstract:The diameter and velocity of spray droplet on different slopes under no wind were measured by two-dimensional video disdrometer. The change regularities of average droplet diameter and its cumulative frequency along spray direction under different slopes were studied. The relationship between the average droplet diameter, velocity and slope were established. Based on the calculation method of water distribution, the model for calculating droplet kinetic energy intensity distribution of sprinkler irrigation on sloping land without wind was proposed. The model was validated by experiment. The Rainbird LF1200 sprinkler was selected as the research object, and the influences of sprinkler layout, spacing and slope on the kinetic energy intensity distribution of combined sprinkler were mainly analyzed by the model. The results showed that droplet kinetic energy intensity distribution uniformity and the proportion of high value area of kinetic energy intensity were both decreased as the sprinkler spacing was increased. The effect of slope on kinetic energy intensity distribution was insignificant. Layout of sprinklers with triangular lattice was useful to decrease kinetic energy intensity of the sprinkler on sloping land. If the Rainbird LF1200 sprinkler was used for designing sprinkler irrigation system on sloping land, the sprinkler spacing was recommend as 0.8 times of the spraying range on flat ground with the triangular lattice layout, considering the impact of kinetic energy intensity and water distribution simultaneously.

Abstract:In order to explore the adaptation mechanism of spring wheat in arid oasis region habitat, the photosynthetic response of spring wheat was investigated by six irrigation treatments. The four light response models was comparative analysis, including rectangular hyperbolae model, non-rectangular hyperbolae model, exponential model and correction model of rectangular hyperbolae model. Then the optimal model was selected and the photosynthetic characteristics parameters of spring wheat were calculated by the optimal model with different irrigation schedules. The results showed that the photosynthetic performance of wheat leaves was increased by the increase of irrigation quota, and the photosynthetic performance in early stage of filling was greater than the late stage of filling. There was significant difference between the four light response models in different irrigation quotas. The simulate values of higher irrigation treatments were more accurate than those of lower irrigation treatments by rectangular hyperbolae model, non-rectangular hyperbolae model and exponential model. The correction model ofrectangular hyperbolae model had the maximum simulation accuracy by error tests. So it was optimal model to fit light response curves of spring wheat in desert oasis. The photosynthetic parameters showed that maximum net photosynthesis rate (Pmax), apparent quantum efficiency (Q) and light saturation point (Is) of 420mm treatment were higher than those of others, but the light compensation point (Ic) was decreased significantly. Therefore, the appropriate irrigation treatments can expand the light adaption ranges of spring wheat, improve light energy utilization and promote the increase of yield in desert oasis.

Abstract:In 2014—2015 and 2015—2016, a field experiment was conducted at Tongzhou Experimental Station of China Agricultural University, Beijing, to study the effects of nitrogen application frequencies on the yield and nitrogen utilization of winter wheat under fertigation with a center pivot system. The experiment set one time at jointing stage (T1), two times at jointing and filling stages (T2), three times at recovering, jointing and filling stages (T3), and four times at recovering, jointing, flowering and filling stages (T4), with consistency of irrigation and nitrogen rates during the whole growth period of winter wheat. The effects of nitrogen application frequencies on yield, ground biomass, plant nitrogen utilization, the grain protein content of winter wheat and the dynamic variation of soil nitrate content were evaluated. The two-year results showed that nitrogen application frequencies had a significant effect on the yield of winter wheat and the treatment T4 obtained the highest yield (9128.5kg/hm2 and 9092.3kg/hm2, respectively). No significant differences existed in total biomass of winter wheat between nitrogen application frequencies, while the distribution of biomass was affected significantly by nitrogen application frequencies in different growth periods. The treatment T4 greatly increased the harvest index, protein yield and nitrogen partial factor productivity of winter wheat. The soil nitrate content in depth of 0~40cm exceeded the average value when nitrogen was applied with low rates and high frequency during the whole growth period of winter wheat. Comprehensively, the fertilizer management of adopting base fertilizer and nitrogen application of treatment T4 was suggested during the growth period of winter wheat under center pivot irrigation system.

Abstract:Under the field experiment, two kinds of water management models were set up for controlling irrigation and flooding irrigation, and six nitrogen fertilizer levels of 0kg/hm2, 60kg/hm2, 85kg/hm2, 110kg/hm2, 135kg/hm2 and 160kg/hm2 were set up to study the effects of different nitrogen fertilizer and water regulation on carbon and nitrogen content and soil respiration in rice, at the same time, the rice yield of different treatments was determined to provide the countermeasure for the water and fertilizer pattern in cool area. The results showed that the content of carbon and nitrogen in different organs of rice and the soil respiration with control irrigation were larger than those with flood irrigation. The change of carbon content in different organs was similar but inconsistent, compared with control, with the increase of nitrogenous fertilizer, the amplitude of fluctuation was not significant（P>0.05). The results showed that with the increase of nitrogen fertilizer, the content of nitrogen were increased in different organs, that of the 135kg/hm2 and 160kg/hm2 treatments were significantly higher than that of other treatments （P<0.05), while that of the same treatment was decreased with the growing period. However, in the case of C/N in different organs, that of the 135kg/hm2 and 160kg/hm2 treatments was significantly smaller than that of other treatment （P<0.05). It was not conducive to the accumulation, metabolism and distribution of carbon and nitrogen in rice plants. According to the analysis of different soil respiration rates, the soil respiration rate of 110kg/hm2 treatment under two kinds of water treatment conditions was higher than that under other nitrogen fertilizer treatments. Under the precondition of considering yield synthetically, C110 treatment was the best coupling model of water and fertilizer, which should be paid attention to. The research result can provide scientific support for water saving and nitrogen reduction in the cold region of Heilongjiang Province.

Abstract:Aiming to explore the mild salinization area ratio of different water and nitrogen physiological characteristics, yield and quality of drip-irrigated cotton, the influence of irrigation water use efficiency and nitrogen partial productivity, seek water and nitrogen combination suitable for cotton cultivation in salinization area, and optimize the salinization area for drip irrigation cotton basis, barrels and randomized trials were used, three irrigation levels of 2750m3/hm2, 3750m3/hm2 and 4750m3/hm2 (W1, W2 and W3) and three nitrogen levels of 300kg/hm2, 600kg/hm2 and 900kg/hm2 (N1, N2, and N3, form of nitrogen in urea) were set up in mild saline soil, and the photosynthesis, fluorescence, yield and quality of cotton, water and nitrogen use efficiency and optimal irrigation fertilization mode were investigated. The results showed that mild salt stress under the condition of different water and nitrogen regulations, irrigation water and the interaction of water and nitrogen had significant effects (P<0.01) on Pn,Tr and Gs and Ci in the growth period, under the level of W1 and W2, Pn, Tr and Gs were increased with the increase of N application rate and then decreased, and reached the maximum at W2N2 treatment. At the level of W3, it was increased with the increase of N, while Ci showed the opposite trend. The influence of irrigation water on Fv/Fm and Fv/F0 of different growth stages of cotton was not significant (P>0.05), and it had significant influence on qp and NPQ, Y(Ⅱ) and ETR (P<0.05). The effect of nitrogen application on NPQ in the growth stage of cotton was not significant (P>0.05), and it had significant influence on Fv/Fm and Fv/F0, qp, Y(Ⅱ) and ETR (P<0.05). The effect of water and nitrogen interaction on the fluorescence parameters of cotton in growing period reached a significant level (P<0.01). The effect of water and nitrogen interaction on Y, iWUE, NPFP and macron values reached a significant level (P<0.01). Among them, the maximum yield of seed cotton (Y) appeared in W2N2 treatment, as 5854.5kg/hm2;the minimum value appeared in W1N1 treatment, which was 3483.75kg/hm2, with a relative increase of 68.05%;through the multiple regression analysis and the likelihood function group, the optimal irrigation water and nitrogen application rate of the mild saline-alkali soil were 3740m3/hm2 and 754kg/hm2, respectively.

Abstract:In order to further investigate the uptake of fertilizer-N at different growth stages and in the partitioning of accumulated N in transplanted rice, field experiments were combined with micro-area test, and the traditional flooding irrigation was used as control, three N rates (85kg/hm2,110kg/hm2 and 135kg/hm2) were set and three 15N-labelled fertilizer application treatments were conducted in rice with different fertilizer-N recovery efficiencies. The fertilizer-N recovery efficiency of total fertilizer was measured, and the fertilizer-N recovery efficiencies of basal, tillering and panicle fertilizations were analyzed by applying 15N-labelled urea as basal, tillering or panicle fertilizer, and comparative study of the two kinds of irrigation fertilizer at different nitrogen utilization rates. The result showed that compared with the traditional flooding irrigation, rice irrigation control model significantly increased dry matter accumulation, nitrogen accumulation and yield of rice, had the “water-saving and high-yield” role. About 16.49%~22.23% of different nitrogen amounts of total nitrogen accumulation in rice under nitrogen fertilizer, the difference between different irrigation methods was not significant;the difference between different irrigation methods was not significant;different nitrogen levels control irrigation rice total fertilizer-N recovery efficiency was 31.82%~36.29%, the fertilizer-N recovery efficiency of basal fertilizer was 10.91%~15.36%, the fertilizer-N recovery efficiency of tillering fertilizer was 34.84%~36.90%, the fertilizer-N recovery efficiency of pancile fertilizer was 55.78%~63.85%. The rice control irrigation mode in addition to fertilizer-N recovery efficiency of basal fertilizer in rice were lower, total, tillering and panicle fertilizer-N recovery efficiency was better than those of the traditional flooding irrigation. The correlation analysis showed that fertilizer-N recovery efficiency of total fertilizer had a significant positive correlation with fertilizer-N recovery efficiency of tillering fertilizer and panicle fertilizer, which provided a reference for further improving the utilization rate of fertilizer nitrogen under controlled irrigation.

Abstract:Development of automatic monitoring of anaerobic fermentation operational stability is insufficient. An automatic system for monitoring total volatile fatty acids (VFAs) and alkalinity in term of total inorganic carbon (TIC) was designed by following the principle of Nordmann titration method and industrial process computer. The software was designed with platform of Visual Studio 2017 and C# programming after analyzing its functions. The whole system was divided into nine units, including data-sending unit, chifecontrol unit, monitoring unit, moving-control unit, titration unit, cleaning unit, sample-adding unit, I/O control unit and data-collecting unit. It can not only accurately measure the concentration of VFAs and TIC, but also send the results and suggestion to users through internet. Furthermore, all above nine units completed and made sure they communicate each other successfully, testing and verifying accuracy and precision through series experiments. The experimental results showed that both accuracy and precision of this system were over than 95% in test of digested chicken manure, which was higher than the results from manual titration. The results indicated that this automatic system would have an important practical application for biogas projects.

Abstract:Nutrient-rich biogas slurry containing N and P is potential culture media for microalgae. Some researchers also conducted a series of relative studies. However, the effect of different biogas slurry on the subsequent microalgae culture is significantly different because the miscellaneous germs in biogas slurry can inhibit the microalgae growth. Furthermore, the variety and quantity of bacteria in biogas slurry digested at medium temperature (35℃) and high temperature (55℃) are also significantly different. However, fewer systematic comparison of biogas slurry digested at medium temperature (35℃) and high temperature (55℃) is found based on microalgae culture. Therefore, the Chlorella pyrenoidosa (FACHB-5) and the Chlorella vulgaris (FACHB-8) were employed as algae species in this experiment. The effect of broth being the culture medium (BG11) mixed with the autoclaved and non-autoclaved biogas slurry of pig manure after anaerobic digestion at 35℃and 55℃ on following microalgae growth was studied by using artificial climate incubator. The specific culture temperature, light intensity, continuous light period, air flow and additive ratio of biogas slurry were (26±1)℃, 4000lx, 24h, 1.5L/min and 20%, respectively. The results indicated that the effect of biogas slurry digested at 55℃ was better than that of biogas slurry digested at 35℃, and the growth rate of microalgae obvious cultured in the biogas slurry of anaerobic fermentation at 55℃ was more superior. Moreover, there was no difference in early adaptation period of microalgae growth between autoclaved biogas slurry and non-autoclaved biogas slurry. However, the growth rate of microalgae cultured in autoclaved biogas slurry was slightly optimal in middle and late period. What’s more, the algae species used in this experiment could adapt to the culture environment with biogas slurry addition well. The growth of Chlorella pyrenoidosa (FACHB-5) was superior to that of Chlorella vulgaris (FACHB-8). The microalgae also decreased the ammonium nitrogen, total nitrogen, total phosphorus and chemical oxygen demand (COD) in biogas slurry significantly, which was favorable for the purification and comprehensive utilization of biogas slurry. The research provided a theoretical basis for the subsequent research and application of microalgae culture with biogas slurry.

Abstract:Anaerobic digestion is a promising technology by which crop straw can be biologically transformed into biogas. However, the efficiency of anaerobic digestion was significantly influenced by the complicated structural resistance from lignocellulose. Therefore, aerobic digestion was used to break down the structure of lignocellulose before anaerobic digestion process. The TRIZ theory was applied to design aerobic-anaerobic combined digestion process of rice straw, and the effects of different aeration modes and addition of fungicides on the fermentation characteristics were studied. The results showed that after aerobic digestion process, the degradation rate of lignocelluloses in each group was increased to some extent. The degradation rate of lignocellulose was the highest in the aerated group added mixed bacteria, and the degradation rates of hemicellulose, cellulose and lignin were 46.3%, 40.4% and 8.2%, respectively. The modified Gompertz equation and the first-order equation could well fit the cumulative methane production, with R2 greater than 0.97. The cumulative methane yield of the aerated group added mixed bacteria in the experiment was 294.38mL/g, which were 279.58mL/g and 320.11mL/g fitted by two equations, respectively. The calculated methane yield was 424.7mL/g calculated by the Baswell formula. The test value was about 69% of the theoretical methane yield which was higher to predict methane yield for inert substances such as rice straw. The total VS degradation rates of aerobic exposure group, aerated group added Trichoderma, aerated group added Aspergillus niger, aerated group added mixed bacteria of Trichoderma and Aspergillus niger and mixed group added mixed bacteria of Trichoderma and Aspergillus niger were 15.99%, 35.47%, 37.99%, 54.68% and 40.92% higher than that of direct anaerobic fermentation group, respectively. The effect of aeration was better than that of mixing for oxygen supply. The effect of adding mixed bacteria in aeration process was better than that of adding single bacteria. 

Abstract:Novel corncob-derived solid acid catalysts, which used corncob as a precursor, were successfully synthesized for the first time by hydrothermal method under saline condition. The effects of different preparation parameters on the catalytic activity of the corncob-derived solid acid were investigated by using the esterification reaction of oleic acid with methanol. The structure-function relationships of the resulting catalysts were also discussed in detail on the basis of the analysis of structure and composition. Then, the catalytic activity of the resulting solid acid was investigated by using the esterification reaction of waste cooking oil with high acid value. The results indicated that the presence of ZnCl2 yielded a preferable carbonaceous structure composed of polycyclic aromatic carbon sheets in short carbonization time. Compared with the conventional method, the carbonized rate of corncob under saline conditions was increased by 1 time, which also produced a suitable structure for sulfonation process. The resulting solid acid possessed high SO3H density, which caused 4.5 times higher esterification yield of methyl oleate than the solid acid prepared by conventional hydrothermal method. Moreover, the corncob-derived catalyst synthesized under optimized saline conditions exhibited higher catalytic activity in esterification reactions of waste cooking oil, yielding 90.23% fatty acid methyl ester in only 4h.

Abstract:In order to decrease the freeze-drying time and reduce the process energy consumption, frozen coffee materials with prefabricated porosity were prepared and freeze-dried to explore its influence on freeze-drying experimentally. Instant coffee was selected as the solute in aqueous solution. Results showed that freeze-drying can be remarkably enhanced with the initially unsaturated frozen material compared with the traditionally saturated one. SEM images of dried products revealed that the initial unsaturated material had the spherical and uniformed porous structure, which was favorable to migration of sublimated vapor and improvement of the drying rate. Chamber pressure, which was ranged from 11Pa to 33Pa, had little effect on the freeze-drying process and increasing ambient temperature can be beneficial to the freeze-drying process. Combined heating can significantly reduce the drying time further. When the temperature was above 45℃, the saturated material was found to collapse causing the failure of freeze-drying. In contrast, the unsaturated one can bear higher operation temperature resulting in a relatively high drying efficiency. The conventionally saturated material experiences the raising rate stage, constant rate stage and falling rate stage during freeze-drying, while the unsaturated material was always in the falling rate stage throughout the process. Freeze-drying of initially unsaturated material would impose significant effect on the traditional freeze-drying process of agricultural products.

Abstract:The impact of emulsifier type (soy lecithin (SL), decaglycerol monooleate (PGE18), decaglycerolmonolaurate (PGE12), sucrose ester (SE15), Tween 80 (T80) and whey protein isolate (WPI)) and carrier oil (soybean oil (SO) and medium chain triglyceride (MCT)) on the properties and stability of zeaxanthin dipalmitate (ZDP)fortified emulsions was investigated. The oil in water emulsions using MCT as carrier oil exhibited better physical and chemical stability than the SO emulsions among all emulsifiers, with the exception of T80. PGE18 produced emulsions with the best overall properties and stability. The impact of PGE18 concentrations on the property of ZDP-fortified emulsions was therefore investigated further. The results showed PGE18 at concentration of 0.8% produced emulsions with significantly smaller droplet size and higher particle charge,either preparing with SO or MCT, while MCT emulsion (177.7nm) had smaller droplet size than SO emulsion (200.2nm). Increasing ZDP contents in emulsion from 4nmol/g to 32nmol/g emulsion had no effect on droplet size and particle charge, and produced a color change from light yellow to orange-yellow. Briefly, the ZDP emulsion prepared by PGE18 (0.8%) and MCT through high pressure homogenization had droplet size smaller than 200nm and adequate particle charge (about -16mV), and remained about 90% of the original ZDP after 28 days’ storage at 4℃, which might be used as a potential zeaxanthin supplement or natural pigment in food and beverage products.

Abstract:The sensitivity of soy protein isolate to trypsin was characterized by its flexibility. The effects of different homogenization pressures (0~200MPa) on soy protein isolate flexibility and emulsifying properties were investigated. The changes of soy protein isolate structure and the correlation analysis between flexibility and emulsifying properties (emulsifying activity and emulsion stability) were also investigated. The results showed that when the homogenization pressure was 0~160MPa, the soy protein isolate flexibility was increased with the increase of the homogenization pressure, while the flexibility did not change obviously at 160~180MPa. When the homogenization pressure was 180~200MPa, the soy protein isolate flexibility was declined. The surface hydrophobicity was increased with the increase of homogeneous pressure, while the turbidity was decreased. The changing tendency and flexibility of the emulsification property with homogeneous pressure were consistent with the homogeneous pressure. Correlation analysis suggested that the soy protein isolate flexibility had a linear positive correlation with the emulsifying activity and the emulsifying stability, and the correlation coefficients were 0.893 and 0.938, respectively. Through ultraviolet spectral scanning analysis of soy protein isolate and endogenous tryptophan fluorescence spectroscopy analysis, it was found that as the conformational flexibility of soy protein isolate was increased, the structure became more stretch.

Abstract:Soybean protein isolate-anthocyanin complex system was used as the object of study. The interaction between soybean protein and anthocyanin was explored by fluorescence spectroscopy, UV-Vis spectroscopy, Fourier transform infrared spectroscopy and circular dichroism. The effect of anthocyanins on the structure of soybean protein isolate was studied by Fourier transform infrared spectroscopy and circular dichroism. The effect of anthocyanin on the structure of soybean protein isolate was studied by Fourier transform infrared spectroscopy and circular dichroism. The results showed that anthocyanin had strong fluorescence quenching effect on soybean protein isolate in a static mode. The apparent binding constants of anthocyanin and soybean protein isolate at 298K, 306K and 314K were 3.343×104L/mol, 4.507×104L/mol and 5.525×104L/mol, the corresponding binding sites were 0.9178, 0.9546 and 0.9381, respectively. The results of thermodynamic data showed that the interaction between anthocyanin and soybean protein isolate was mainly hydrophobic interaction. Synchronous fluorescence spectroscopy and UV-Vis spectra showed that anthocyanins changed the microenvironment of aromatic amino acid residues in the spatial structure and the conformation of soy protein isolate, and the synchronous fluorescence spectrum showed that the anthocyanin interacted with the tryptophan residue in the soybean protein isolate and reduced the hydrophobic interaction. Fourier transform infrared spectroscopy and circular dichroism showed that the secondary structure of soybean protein was changed by anthocyanin.

Abstract:Articulated vehicle is one of the utmost members of intelligent mining equipment and working under terrible conditions, which has the special steering structure and driving characteristics. In order to improve the tracking accuracy and response speed of the articulated vehicle, a linear quadratic regulator (LQR) strategy based on predictive information was proposed and a genetic algorithm (GA) was used to optimize the state quantity matrix, and the optimal LQR state feedback controller was obtained to realize the precise path tracking control of the articulated vehicle. The control result was reflected by the displacement deviation, the heading deviation and the curvature deviation. In the co-simulation (ADAMS-Matlab/Simulink) results, the displacement deviation was 0.03m, the deviation error was 1.3%, the heading deviation error was 0.19%, and the curvature deviation converged to be 0.003m-1. The co-simulation and experiment results showed that the proposed control method can effectively improve the control precision. The control strategy proposed can achieve the precise and stable path tracking of articulated vehicles, which was an alternative control method.

Abstract:In order to improve the reliability of vehicle running state estimation, a vehicle state fusion estimation method based on multi-model observer error compensation and iteration was proposed. A strong-tracking filter estimation algorithm was presented for vehicle state estimation based on three-degree-of-freedom vehicle dynamics model, meanwhile, using the coupling relationship of four wheel speed, a ridge estimation algorithm for vehicle state estimation was designed considering the influence of data disturbance and ill-conditioned matrix. To further improve the reliability of estimation system, an estimation strategy with the error compensation and iteration between the dynamic-model-based observer and the kinematic-model-based observer was developed, a fuzzy controller was designed which was used to judge the weight of strong tracking filter and ridge estimator according to the real-time pseudo measurement value of sideslip angle and longitudinal slip rate, and then estimation performance was improved by iteration and fusion of the closed-loop estimation system. The results of the simulation and road test showed that the proposed vehicle state fusion estimation method can integrate the advantages of strong tracking filter algorithm and ridge estimation algorithm, dynamically adjust the weight coefficients of strong tracking filter and ridge estimation results according to the vehicle longitudinal slip ratio and sideslip angle, guarantee the estimation accuracy and synchronously improve the adaptability of the estimation system under multiple conditions.

Abstract:Cam profile is a key point to the design of high-pressure fuel system. It has a direct influence on the movement of the plunger, which affects the pressure characteristics of the pump. Based on the electronic controlled unit pump (EUP), the dynamic relationship between the cam profile and the pumping pressure was studied by means of experiment and simulation. It was found that within a certain period, the peak pressure was increased with the increase of injection duration using a constant speed cam profile, but the rising rate was decreased with the increase of the injection duration, and the peak pressure tended to be a constant value if the duration was long enough. With deceleration cam profile, the pump can reach approximately constant pumping pressure within common engine injection duration by adopting the dynamic performance in transitional period, in which the pressure was increased firstly and then decreased. In order to evaluate the quality of the constant pressure performance, an evaluation parameter was put forward, which was called constant pressure coefficient, and the influence of the acceleration rate in working section on the constant pressure coefficient was studied. Finally, in order to reach the constant pressure characteristic, a selection method of the optimum cam profile was put forward for different matching speeds. A supply cam profile was designed for a certain engine with a -0.013mm/(°CA)2 deceleration rate of working section and a good constant pressure characteristic (10~15°CA injection duration) and maximum cycle injection volume (438mm3) at engine speed of 1200r/min were obtained.

Abstract:Analyzing mobility of parallel mechanisms digitally and automatically is the foundation of automatic type synthesis of parallel mechanisms. The mobility of parallel mechanisms was analyzed automatically based on R(3,3) geometric algebra model, which was a R6 geometric algebra model. Firstly, since any screw can be represented by a known screw with rigid body transformations, and the rigid body transformations can be derived by the geometric relationship between the two screws, when the twists of the first joints of the limbs were known, all twists of limbs of a parallel mechanism can be symbolically expressed and automatically computed by the geometric relationships between the joints of limbs. Then, since the motion of the limb was the union of all twists of joints and the motion of the moving platform was the intersection of all motion of limbs, by taking the advantages that the geometric algebra had the representations of the intersection set and union set, the motion of all limbs and the moving platform can also be symbolically expressed and automatically computed. Moreover, the symbolic expression of the motion of moving platform was exactly the moblity of the parallel mechanism. And the degree of a parallel mechanism was given by the blade of the symbolic expression. Finally, some examples were discussed in details by using the C++ coding to verify the proposed algorithm. The algorithm that analyzing the mobility of parallel mechanisms automatically based on geometric algebra did not need to compute the constraint twists of limbs and solve linear equations, which made this algorithm faster and more efficiency. This algorithm set the stage for automatic type synthesis of parallel mechanism.

Abstract:3-DOF parallel mechanism (PM) is widely used in manufacturing since, which is simple and flexible. According to the PM design theory and method based on the position and orientation characteristic (POC), a novel two-translation and one-rotation (2T1R) asymmetric spatial PM without parasitic motion, RPa‖3R-R+RSS, was designed. Firstly, the topology characteristics of the PM were analyzed, including POC of the platform, the DOF and the coupling degree (к), which demonstrated that the PM was zero coupling degree and of partially decoupled motion. Secondly, the analytical modeling of the forward and inverse position solutions was derived by using kinematics method based on ordered SOC units. In addition, the direct and inverse kinematics were verified by numerical methods using Matlab. And then the shape and size of workspace and rotation capability of the PM were analyzed. Finally, conditions of singularity of the PM were discussed, and velocity and acceleration of the PM were calculated and simulated. This PM had advantages of simple structure and easy manufacturing, which can be used to convey, assemble and position operations in manufacturing. The analysis results indicated that the kinematics analysis of the PM was not complicated, the rotation capability was strong and the performance of dynamics was better.

Abstract:Magnetorheological valve (MR) is a typical smart control mechanism that using magnetorheologcial fluid as the working fluid. The advantages of simple operation, fast response, and regulating pressure drop make the MR valve have a promising application prospects in the hydraulic system. In order to broaden the industrial applications of MR valve, a radial flow MR valve controlled cylinder system was proposed, which consisted of a radial flow MR valve, a single rod hydraulic cylinder and an accumulator. The working principle of radial flow MR valve controlled cylinder system was described in detail. The mathematical model of damping force was deduced, and the simulation analysis was also carried out. At the same time, the dynamic test rig was set up to investigate the dynamic performances of the typical and improved radial flow MR valve controlled cylinder systems under different currents, frequencies, and amplitudes. The experimental results showed that radial flow MR valve controlled cylinder system can output a large damping force, and the maximum damping force can reach 5.8kN. Furthermore, the damping force can be continuously adjusted under different applied currents, and the adjustable range was wide. The effect of piston velocity on the damping force was little, and the system can output stable damping forces under a variety of operating conditions. The comparative analysis of two different valve controlled cylinder systems also showed that different dynamic performance can be obtained by replacing different MR valves.