Abstract:Alfalfa is one kind of high-quality forage grass. With the development pattern expanding from food crop-commercial crop-forage, ternary structure, to food crop-commercial crop-livestock-forage，quaternary structure, the domestic demand for alfalfa is increasing. In order to provide references and supports for the development of alfalfa industry in China, and propose appropriate full-mechanized alfalfa production development patterns which are suitable for China, the present situation of alfalfa mechanized production technology in China and foreign countries were reviewed, summarized and analyzed. The full-mechanized alfalfa production technical pattern included seven mechanized production technology, i.e. alfalfa seed project, cultivation, sowing, field management, high-quality harvest, storage and transportation, and forage products processing, with more than thirty production links. For now, a suitable mechanization technology system for alfalfa production has initially formed in China, which means that available equipment could be found and used during the production operation with not completing machine matching, high production cost and low-efficiency problems. Certain gaps about the alfalfa mechanized production technology existed between China and foreign countries. Issues of uneven development of production processes, short boards in the mechanized production technology, low industrialization, basic research backward, poor linkage and reliability of equipment of the mechanized production operation still existed. Establishing a complete full-mechanized technology system for alfalfa production, developing a special alfalfa mechanization technology system with Chinese characteristics, strengthening theoretical system research of soil-alfalfa-machine interaction, and realizing alfalfa production machinery with integration as well as intellectualization,would be the development direction of alfalfa mechanized production technology system in China.

Abstract:When a picking robot is able to quickly estimate the viscoelastic parameters of the fruits and vegetables in the process of grasping, an optimization of the grasping process in real time can be carried out and the mechanical damage caused by the end-effector can be alleviated. Artificial neural network (ANN) model of tomato viscoelastic parameters estimation was established by using grasping force, deformation and acting time as inputs. The force, deformation and time measured by creep test with texture analyzer, as well as the viscoelastic parameters (E1, E2, η1, η2) were used as the training data set to determine the topological structure and parameters of the artificial neural network. Then performance of the network model was tested. A two finger robot end-effector was applied to grasp tomato samples selected randomly, and the ANN model was used to estimate the viscoelastic parameters online during the process of grasping. Compared with the measured value by texture analyzer, when time was more than or equal to 0.2s, the relative error between the estimated value and the measured value were less than 25%, and according to the viscoelastic parameters obtained from the 0.2s time, the range of the robot’s grasping force was estimated. The results showed that the method could be used to estimate the viscoelastic properties of the grasped tomatoes during the robot grasping process, which provided the basis for the online optimization of grasping force.

Abstract:In order to use the same end-effector to grasp fruits and vegetables which have various shapes and effectively avoid the end-effector damaging fruits and vegetables under the premise of ensuring capture efficiency, a kind of multifunctional dragonfly claws form biomimetic end effector was designed. Firstly, the relevant physical information of each claw finger of dragonfly was transformed into a data and quantitative model by using a stereomicroscope, and the size of the end of femur was determined through theoretical analyzing, actuating design, modeling and optimization of structure parameters, the length of mechanical front claw’s femur, tibia and the tarsus were 36mm, 48mm and 31mm, respectively, and mechanical median claw’s femur, tibia and tarsus length were 48mm, 48mm and 36mm, respectively. Meanwhile, D-H method was adopted to establish the motion model of the end-effector, and draw the envelope space region of end-effector. The results turned out that the manipulator can fully envelop the main parts of various fruits and vegetables. Finally, the static load test which was on the platform of parallel-mechanism and serial-mechanism was carried out to determine the ultimate stress, and the fruit as well as vegetable grabbing test was also carried out. The average capturing success rates of mechanical hand on the tomato, apple, pepper and eggplant were 90.7%, 88.6%, 87.9% and 87.2%, respectively, and the average damage rates were 4.3%, 0.7%, 3.6% and 2.1%, respectively. The test results showed that the end effector realized the effect of using the same mechanical hand to grab many kinds of fruits and vegetables stably and smoothly.

Abstract:The embedded system based on FPGA+DSP was suitable for the agricultural sorting field, due to its flexible chip selection and high power efficiency. The embedded system was designed based on the principle of detection, software and hardware design and rejection system design. In principle of detection, a polarization channel was added to the UV channel to resolve the problem of transparent film detection without increasing camera. In software design, a speed measurement based on spatial correction and a learning algorithm for threshold detection was proposed to improve the adaptation of the equipment. An embedded solution was put forward which had advantages in both material cost and power consumption. After optimization, the DSP embedded board could stably process camera image data in real time. In rejection system, a control scheme was designed based on target real-time speed. The experiment result showed that the speed measurement scheme was verified via roller platform, and cotton speed can be obtained in the production line test. The embedded system could meet the real-time requirement, and the system was stable under varying foreign fiber numbers in long-term test. Concerning the test of rejection system, an impact test was performed by changing the wind speed. Finally, two typical foreign fiber detection tests of the system were implemented. The results showed that the detection rates of foreign fibers and polypropylene filaments as well as transparent films were higher than 80%, while the detection rate of yellowish foreign fibers was slightly lower than 80%. In the comparison test with similar equipment, the present equipment revealed superior detection rate. Long-term test result showed that the present equipment was easy to operate and had stable performance.

Abstract:Tobacco topping operation was an important link during tobacco planting process. In order to solve the existing problems such as data transmission problem and tobacco topping height recognition problem of intelligent tobacco topping machine, and enhance the practicability and robustness of detection algorithm, a wireless control system for tobacco topping machine was designed. The system could control tobacco topping operation of two rows at the same time, meanwhile complete the integrated operation of tobacco flower identification, tobacco flower location, tobacco topping and sprout inhibitor spraying. The system working principle was as follows: firstly, wireless routing system was used for image acquisition on the machine. Then MSRCR algorithm was used to preprocess the image, so as to eliminate the illumination effect on the tobacco height identification. Then locating the tobacco flower area in the image by a concentric circle camera calibration algorithm and determining the tobacco topping height. Finally, through the control of single-chip microcomputer, stepping motor and pump were used to complete the tobacco topping operation and sprout inhibitor spraying operation, respectively. The test result showed that the tobacco flower recognition rate of the height detection algorithm under the static test can reach 98.5%;camera calibration accuracy reach around 96%, topping accuracy can reach 95%. The tobacco topping machine had a high topping accuracy rate, precise sprout inhibition, and high system stability, which met the agronomic requirement of tobacco topping.

Abstract:Considering most of the present combined machines of rotary and subsoiling usually place subsoiling components in front of rotary components, without the research of interaction between these two working components, based on the interaction between subsoiling and rotary tillage components, a combined tillage implement of reverse-rotary and subsoiling for deep ploughing was designed and developed. The overall implement aimed at deepening the working depth, improving the working quality and reducing tillage resistance, with focus on the interaction research of the process of rotary tillage and subsoiling components. Whole implement parameter was optimized by discrete element method (DEM), orthogonal experiment and finite element analysis (FEM) simulation. As indicated in the results of simulated orthogonal experiment, working quality was the best when operation speed was 1.8km/h, rotary speed was 350r/min, rotary blade type X was IIT195, in which case particle amount of heap soil quantity was 5283, straw coverage was 98.37%;the results of DEM demonstrated that the strength met the working requirements. Field test based on optimal parameters showed that rotary tillage depth was 182.8mm, subsoiling depth was 388.4mm, surface flatness was 18.3mm and soil bulkiness was 17.22% for the combined tillage implement of reverse-rotary and subsoiling;rotary tillage depth stability, subsoiling depth stability and straw coverage were all beyond 90%, which completely met the soil preparation requirement in deep layer. Compared with combined subsoiling and rotary cultivator, this combined tillage implement of reverse-rotary and subsoiling had better consistence of working depths, higher vegetation coverage and the tillage resistance was reduced by 16.21% under qualified working quality, and it had high working stability and reliability. The development of this implement can provide reference for deep layer cultivation and tillage resistance combined cultivator in arid areas of North China.

Abstract:Paddy field mechanization ridging is constructed by agricultural machinery to meet the production requirements of rice irrigation and ridge technology. It can improve the yield of grain crops and reduce the waste of water resources, which is conducive to the construction of standardized farmland in China. In order to improve the quality of paddy field mechanization ridging and investigate the working parameters of performance of hanging unilateral ridger, the interaction model of machinery and soil was established by using distinct element method. The EDEM software was employed to simulate the processes of rotary tillage collecting soil and compacting ridging. And then the dynamic behaviors of performance and power consumption of ridger were researched under the working conditions. The principal factors which affected the quality of machine operation were analyzed. Orthogonal simulation experiment was carried out with forward speed, rotational speed, tillage depth as experimental factors and ridge density and power consumption as assessment consumption. Based on experimental data, a mathematical model was built by using the Design-Expert 6.0.10 software, and the experimental factors were optimized, the best combination was achieved. By using range analysis method and variance analysis method to determine the importance index, the primary and secondary indexes were as follows: forward speed, tillage depth and rotational speed. And the experiment results showed that forward speed was 0.3m/s, rotational speed was 470r/min, tillage depth was 200mm, and the maximum ridge density was 1890.0kPa, the minimum power consumption was 30.07kW, and the improved power consumption exceeded the original one by 9.93kW. Finally, the bench test was conducted to verify the accuracy of simulation results and optional parameters, which showed that the relative error of ridge density was 4.26% and the relative error of power consumption was 5.11%, indicating that the simulated values were basically coincided with testing values, which proved that the modeling and simulating methods adopted met the content requirement.

Abstract:The object was to obtain the forces of soil on compacting ridge device of ridger when operating. Taking 1DSZ-350 type hanging unilateral rotary tillage compacting ridger for paddy field as research carrier, a kinetic parameters measurement system was designed for compacting ridge device using strain sensor, and a kinetic test bench was set up. The operation parameters of compacting ridge device were measured, and the variation rules of the force of soil on pinnae, and the relationships between ridge compaction and forward speed and rotation speed of compacting ridge device were obtained, which was carried out through single factor experiment with the forward speed and rotation speed of compacting ridge device as experiment factors, the force of soil on pinnae and the compaction of ridge in the process of building ridge as experiment indicators. The results showed that when the rotation speed of compacting ridge device was fixed , with the increase of forward speed of machinery, the average value of force of soil on pinnae was increased, and the compaction of ridge was decreased, which was in the range of 2838.1~5695.2N and 2250~1680kPa, respectively. When the forward speed of machinery was fixed, the average value of force of soil on pinnae and the compaction of ridge were increased with the increase of rotation speed of compacting ridge device, which was in the range of 3203.8~5990.3N and 1460~2180kPa, respectively. According to the test results, the test system for operation parameters of compacting ridge device can meet the requirements, which can provide important reference for the relevant parameters test of similar device.

Abstract:To increase the qualified rate of sowing depth and the qualified rate of film hole for electric driving maize planter with dibbling on membrane, forward speed compensation device and limited depth mechanism were calculated. With Matlab impact of parameters of speed compensation mechanism on dibbling trajectory were simulated. Screening out that crank angular velocity, center distance and assistant crank length have significant impact on qualified rate of sowing depth and the qualified rate of film hole. According to response surface method with 3 factors and 3 levels, multi-factor variance analysis was conducted. Results showed that influence on the qualified rate of sowing depth was order, center distance, assistant crank length and crank angular velocity, and influence on qualified rate of film hole was order, assistant crank length, crank angular velocity and center distance. To get maximizing the qualified rate of sowing depth and the qualified rate of film hole, optimal parameters was that crank angular velocity was 89.10rad/s, center distance was 58.55mm, and assistant crank length was 95.1mm. Under that condition, the qualified rate of sowing depth and the qualified rate of film hole respectively was 94.89%, 93.61%. Test process showed that speed compensation mechanism run smoothly and reliably, and results met standard requirements related to seeder and agricultural requirements for maize planting in Gansu.

Abstract:In order to meet the requirement of high-speed and precision sowing operation of soybean, a spoon seed metering device was proposed, and its basic structure and working principle were analyzed. The numerical calculation method was used to design the plate and partition of the seed metering device. The diameter of the plate was designed as 260mm, the number and radius of spoon were inversely proportional, and the angle of the mouth on the partition was from 5° to 90°. The optimal ranges of the radius and the inclination angle of the scoop were determined by single factor tests, which were obtained through simulation experiment by EDEM. The structure of the scoop edge was optimized through simulation experiment, and the optimal seeding performance was obtained when the scoop edge was inclined to both sides. The quadratic orthogonal rotation combination test was designed and the experimental data was processed by the Design-Expert 8.0 software. The regression model was established for the radius and inclination angle of the spoon about the qualified index and missing index. The optimal parameters of the scoop were radius of 6.8mm, inclination angle of -9.4°, thickness of 2.2mm and length of 14.1mm, with the qualified index of 95.1% and the missing index of 0.6%. The physical prototype was processed according to the optimal parameters and the bench test was carried out with results in accordance with simulation tests. The qualified index of the seeder was above 93% and the missing index was less than 3% when the speed of the planter was in the range of 6km/h to 12km/h, which satisfied the requirement of high-speed and precision sowing.

Abstract:Currently, studies about aerial spraying application of agricultural unmanned aerial vehicle (UAV) in China mainly focus on the effect of aerial spraying operation parameters (flight height and flight velocity) of single-rotor UAV on droplet deposition distribution. In fact, the main factor that affects the droplet deposition distribution of aerial spraying is the wind field below the UAV rotor, which is made up of wind field generated by rotating rotor and wind field of external environment. The effect of wind field below agricultural UAV rotor needs to be taken into account in the study of the distribution regularity of aerial spraying droplet deposition. Moreover, the wind field generated by multi-rotor electric UAV during operation is the result of multiple rotor interaction. The distribution of wind field and the effect of wind field on the distribution regularity of droplet deposition are different with single-rotor UAV. In order to reveal the impact mechanism of droplet deposition distribution by the wind field below the multi-rotor electric UAV rotor, wind field distribution below multi-rotor electric UAV was measured by using a wireless wind speed sensor network measurement system for unmanned helicopter, and the impact on the distribution of droplet deposition was analyzed by the wind field in X, Y and Z directions below rotor combined with the condition of aerial spraying droplets deposition in rice canopy, and the regression model was established by making the variance analysis and regression analysis of experiment results. The results showed that the trends of droplet deposition in the plant layers were basically similar, the deposition amount of droplet was decreased from upper layer to lower layer. Because of the different operating parameters, the distribution of wind field below rotor in each experiment were different, but the value of wind speed in different directions showed the decreasing trend in Z, Y and X directions. Among the three directions wind field below multirotor electric UAV rotor, the wind field in X and Y directions had no significant impact on droplet deposition in the effective spray area, the wind field in Z direction had an extremely significant impact on droplet deposition in the effective spray area, the Sig. value was less than 0.001. The wind field in X direction had no significant impact on droplet deposition penetration in the effective spray area, the wind field in Y direction had a significant impact and the wind field in Z direction had an extremely significant impact on droplet deposition penetration in the effective spray area, the corresponding Sig. values were 0.037 and less than 0.001. The wind field in X and Y directions had no significant impact on droplet drift, the wind field in Z direction had a significant impact on droplet drift, the Sig. value was 0.036. Furthermore, the horizontal wind field in X and Y directions and the vertical wind field in Z direction all affected the deposition uniformity in the effective spray area. With the smaller value of horizontal wind field in X and Y directions and the larger value of vertical wind field in Z direction, the uniformity of droplet deposition was better, the best value reached 36.44%. In addition, the corresponding determination coefficient R2 of the regression model between droplet deposition in effective spray area and the wind speed in Z direction as well as between droplet deposition penetration in effective spray area and the wind speed in Y and Z directions were 0.868 and 0.842, respectively, and these models can provide guidance for the practical application. The result revealed the effect on the distribution of aviation spraying droplet deposition by the wind field below the multi-rotor UAV rotor, and it had an important guiding significance in the practical application such as reducing liquid drift in aerial spraying and improving the utilization rate of pesticide.

Abstract:Due to great human awareness of environmental conservation and public health, pesticides must be applied in economically viable and environmentally sensitive ways, and it requires deep understanding on the distributions of pesticide application. The distribution is the process occurring immediately after application. When applied, the pesticide can distribute in the following way: loss by wind drift, deposition on leaves or other parts of the target plant and deposition on ground (soil). The sum of these three components (plant, soil and drift) should equal to the amount of spray emitted. However, there are concerns over the intended effect (deposition on plant) and unintended effect (deposition on ground and wind drift) of pesticide application on the effectiveness and risks associated with the use of pesticides. Oriented to distribution of pesticide application, droplet deposition on different parts was measured in the research. Spray deposition was tested by recovery of a fluorescent tracer (pyranine) in the 1.75m wide, 1.75m high and 10m long working section of the wind tunnel. A single nozzle was positioned in the centre of the wind tunnel at a height of 0.6m above the wind tunnel floor and then sprayed moving along the length of the tunnel at a speed of 1m/s. The nozzle moved over the top of the plant so that application amount was the same to a typical spray in agriculture and the pesticide distribution was measured. Mylar cards (plastic) were used to collect the deposition on ground, diameter polythene lines were horizontally mounted to provide an estimate of the wind drift of spray, and the sow thistle plant was put under the nozzle to test the deposition on the target. To evaluate the influence of different factors on spray distribution, the trial was carried out for three plant types (sow thistle, cotton and barnyard grass) at three growth stages (leaf area were 15cm2, 135cm2 and 300cm2, respectively). After spraying, fluorescent dyes were easily washed off the three different samples so good recoveries can be got. The amount of spray on the plant, ground and wind drift was calculated and expressed as a percent (or fraction) of the amount of spray that came out of the nozzle. Based on the frame straddling technique, velocity of droplet was investigated by particle image velocimetry (PIV), and the test system included laser imaging system, pulse generator and analysis software. The influences of droplet size (VMD), droplet velocity, spray angle, flow rate, height of nozzle, wind speed and growth stage of plant on deposition at various parts were investigated. Correlation between different factors and spray distribution (fraction of spray deposited on ground, plant and drift) was calculated to judge the impact. The results indicated that the distribution of the spray was influenced by droplet size, release height wind speed and growth stage. Meanwhile, spray angle, sheet velocity flow rate and plant type had no significant effect on the spray distribution. The ground deposition was the lowest with the fine sprays. It was found that ground deposition from application of pesticides was 57.7% for finer droplet（VMD was 181μm) which was increased to 82.7% for coarser droplet (VMD was 445μm). Deposition on plant surfaces was also found to be more than 13.4% with release height at 40cm to 60cm and wind speed less than 4m/s. For soil-active herbicide, a proportion of deposit on the ground was increased by bigger VMD, and this is a desirable result. For controlling flying pest, airborne deposit can increase chemical’s spread on its body, so smaller VMD was more effective. It was also shown that the proportion of spray depositing on plant surfaces was increased as the plants got larger and the amount depositing on the ground was decreased. The result can be used to effectively aid spray decisions to maximize the effectiveness of pesticides and minimize risks to the environment from chemical spraying activities. Chemical application must be as precise as possible, so populations of unwanted organisms (insects or diseases) can be reduced and less environmental impacts created in the agricultural production. An understanding of the pesticide application process can be utilized to improve the estimate of the distribution on pesticide from a spray operation.

Abstract:In order to overcome the shortcomings of the traditional feeding method, the feeding industry of ruminant gradually adopts the ration feeding technology that mixes the nutrient formula of roughage, concentrate and various additives uniformly. The models of foreign ration mixers tend to serialization and automation, but there are disadvantages such as high price, large power, and strong technical confidentiality, which limit the popularization and application of foreign ration mixers in China. Considering the shortage of mechanism study and innovative research of ration mixers, and the actual needs of animal husbandry in China, for promoting the application of ration feeding technology in China, a rotary ration mixer was designed. In order to reveal the mixing mechanism, the rotary ration mixing experimental device was designed and used to observe and analyze the mixing process by the highspeed photography technology. According to the movement characteristics of material particle group in the drum, the material distribution area was divided into material lifting area, dropping area and material returning area. The dropping area was the main mixing area, in which materials were mixed by main shear mixing and auxiliary spread mixing and auxiliary convective mixing. The location, size and shape of each area were affected by the structural and operating parameters. At the same time, the experimental ration was chosen according to the forage-concentrate ratio of 35∶65 (based on dry matter content). Rotary speed of the drum, loading rate of materials, mixing time, inclination angle of the shoveling plate and height of the shoveling plate were used as experimental factors, coefficient of variation and net power consumption were used as evaluation indexes, the method of orthogonal rotational combination experiment of five factors and five levels was used to carry out the optimization experiment of performance. The experimental results showed that coefficient of variation was 2.09% and net power consumption was 33.734kJ under the conditions that rotary speed of the drum was 23.5r/min, loading rate of materials was 65%, mixing time was 4min, inclination angle of the shoveling plate was 11°, and height of the shoveling plate was 109mm. The results could provide reference for the research and development of ration mixers.

Abstract:The demarcation of permanent prime cultivated land is a method of economical and intensive use of land, and it is one of the effective ways to solve the shortage of cultivated land reserve resources. Taking Qinghe County, Hebei Province as the study area, firstly the cultivated land natural endowments, location conditions, construction levels were considered according to the system of permanent prime cultivated land of China, then the index system of demarcation of permanent prime cultivated land was constructed with result of agricultural land classification, and the cultivated land was classified and partitioned by TOPSIS. The result showed that mainly cultivated land in permanent protection area, adjustment and construction area and primary remediation area was high quality, flat, centralized and contiguous, some of cultivated land could be demarcated as the permanent prime cultivated land. Cultivated land in reserved construction area was low quality, high terrain relief degree, farming difficult and low benefit, and it was not suitable to be demarcated as the permanent prime cultivated land. This study quantified the demarcation of permanent prime cultivated land, and the cultivated land comprehensive quality was sorted by drawing into the TOPSIS, the result could broaden the way of demarcation of permanent prime cultivated land.

Abstract:Supplementing spectral information with spatial information to improve the classification of hyperspectral image is becoming a hot research in recent years. An improved scheme was put forward according to existing methods. An algorithm of supervised classification was proposed which was combined with bilateral filter and pixel neighborhood information (BS-SVM). Firstly, the spatial texture information of hyperspectral image was extracted whose dimensionality was reduced by PCA. Secondly, spatial correlation information was formed by building pixel neighborhood information of hyperspectral image. Finally, spatial-spectral information was merged by the two kinds of spatial information and the spectral information, which was classified by SVM. The BS-SVM classification method was implemented on the hyperspectral data of Indian Pines and Pavia. The results indicated that in the first place, the OA (Overall accuracy) of G-SVM for Indian Pines and Pavia were 3%~4% and 2%~3% higher than those of SVM, the same index for B-SVM were 3%~4% higher than that of G-SVM, and the classification performance can be improved effectively by the spatial texture information of hyperspectral image extracted by bilateral filter. Furthermore, the salt and pepper can be removed effectively by BS-SVM, showing very good performance in hyperspectral classification. In the second place, the classification of some methods for Pavia was better than the Indian. The reason was that the types and distribution of grounds for Indian were more complicated than Pavia. The classification for the less ground were bad, especially the Oats (only 20) was the worst. Therefore, it directly led to the AA (Average accuracy) generally lower than OA. However, the standard deviation of the classification for BS-SVM was much smaller than those of other methods, and the effectiveness of the method was verified with good stability. The experiments showed that the BS-SVM algorithm was better than original SVM with the pure spectrum information, the spatial-spectral information-based methods with Gabor. With the spatial correlation information extracted by the bilateral filter and the pixels neighborhood information, the performance of the classification with BS-SVM algorithm was greatly improved, and the effectiveness of BS-SVM was fully verified in the classification of hyperspectral image.The method can be applied to the field of crop growing, accurate classification and identification.

Abstract:Soybean is an important source of protein and fat. The increase of soybean yield is playing a significant role in guaranteeing food security and satisfying market demanding. Therefore, rapid screening of soybean varieties with high yield and quality is of great significance to increase the total output of soybean. Leaf area index (LAI), which refers to the gross one-sided leaf area per surface area, is one of the critical phenotypic parameters to characterize crop canopy structure, and it has an important significance to evaluate crop photosynthesis, growth and predict yield. A rapid, non-destructive and efficient estimation of soybean LAI can assist the screening of high-yield varieties. Currently, lots of soybean breeding material plots is one the difficulties in soybean breeding, but traditional manual investigation method is time-consuming, inefficient job with certain degree of subjectivity. Unmanned aerial vehicle (UAV) remote sensing technology has become a research focus on precision agriculture application. It features the advantages of easy construction, low operation and maintenance cost and flexible mobility, and has been used to realize rapid, non-destructive, spatial continuous crop growth monitoring and crop yield estimation. Researches based on low-cost UAV high spatial resolution digital images to estimate crop phenotypic parameters mainly focused on the crop cultivation and management sector. However, there are few researches on crop breeding. The high spatial resolution digital images of the Shengfeng academician workstation of soybean breeding experiment located in Jiaxiang County, Jining City, Shandong Province, China from July to September in 2016 were acquired using a low-cost UAV digital camera system. The obtained UAV data contained the high spatial resolution images of growth periods of R1-R2, R3 and R5-R6. At the same time, the average LAI values of 900 breeding plots on the ground were obtained. Firstly, the digital orthophoto map (DOM) was generated. The generated DOM was calibrated using the image values of black and white calibration tarps in the DOM image and a total of eighteen calibrated variables of R, G, B, MGRVI, RGBVI, GLA, ExG, WI, ExGR, CIVE, VARI, G/R, G/B, R/B, R/(R+G+B), G/(R+G+B) and B/(R+G+B) were calculated based on existing research. Secondly, 70% of the total data pairs of the eighteen variables and corresponding groundmeasured data were used to build models, including the unary linear regression, stepwise regression, total subset regression, partial least squares regression, support vector machine regression and random forest regression, while the remaining data pairs were used for model validation. Finally, the optimal prediction model for LAI was selected by comprehensively considering the determination coefficient (R2), root mean square error (RMSE) and normalized root mean square error (nRMSE) of model building and validating. The results showed that the total subset regression, which included four variables of B, RGBVI, GLA and B/(R+G+B), was the optimal estimation model of LAI. The R2, RMSE and nRMSE of model building and validation were 0.69, 0.99, 17.90% and 0.68, 1.00, 18.10%, respectively. The spatial distribution map of LAI of soybean breeding materials area was generated. Compared with ground-measured values and DOM derived from digital camera images, the distribution map could well reflect the growth status of soybean breeding materials. The results showed that high spatial resolution digital images of soybean breeding materials could be obtained quickly using UAV remote sensing technology. After that, the qualitative and quantitative analysis can be carried out to monitor the status of soybean breeding materials in the study area. In general, the UAV remote sensing technology with digital camera was feasible in predicting the LAI of soybean breeding materials, and it can serve as a rapid, effective and non-destructive way for LAI estimation in large-scale soybean breeding area.

Abstract:Due to bad work environment and network transmission failure, it is easy to generate abnormal sensory data in livestock breeding Internet of things system. In order to ensure the quality of sensory data, according to the characteristics of sensory data flow such as periodicity, temporality, infinity, etc., a method was proposed based on sliding window and support vector machines regression (SW-SVR) for livestock breeding Internet of things abnormal sensory data detection in real time. Firstly, the sliding window size was decided according to the characteristic period and sampling frequency of data flow from livestock breeding Internet of things system, and the history data within sliding window was selected as the input value of prediction model. Then, the sensor estimated measurement value at certain moment in livestock breeding Internet of things system was predicted by using SVR model. Finally, the prediction interval (PI) was calculated, and the abnormal sensory data was identified if the sensor actual measurement data fell out of the PI. The abnormal data would be replaced by the predictive data. The abnormal sensory data detection method was tested by data flow from real livestock breeding Internet of things system. Experiment results showed that the mean absolute percent error value of prediction with window size calculated by the sliding window method was 0.1884. The correct detection rate of abnormal data based on SVR model with radial basis function kernel (RBF kernel) achieved 98%, which had higher accuracy compared with BP neural network (BPNN) method. Abnormal data can be effectively detected and treated in livestock breeding Internet of things system.

Abstract:Aiming to identify freshwater fish species automatically, passive acoustic signal samples of common freshwater fish were collected by the HTI-96-MIN standard hydrophone. A wiener filter and a sampling noise reduction method were used to preprocess the samples. Then frequency band energy of the samples was extracted by using wavelet packet decomposition algorithm. The layer number of the algorithm was four. The characteristic vectors of the samples were comprised of short-time average energy, short-time average zero-crossing rate, frequency band energy, and difference among the characteristic vectors of the four classes samples. Furthermore, a probabilistic neural network was used to identify freshwater fish species rapidly. As different values of the smoothing factor σ, the identification effect was studied. The results indicated that the identification accuracy was the highest when the smooth factor was between 9 and 19. The identification accuracies of ctenopharyngodon idellus, megalobrama amblycephala and crucian carp were all 100%. The identification accuracy of passive acoustic signals with zero fish was 77.3%. And the total accuracy was 94.3%. The proposed freshwater fish identification method using passive underwater acoustic signals had higher accuracy and less calculation. It provided a new way for identifying freshwater fish species quickly.

Abstract:The pond water temperature is one of the most important parameters which directly affect the feeding, growth, livability and reproduction of aquaculture animals. Thus it is significant to grasp the pond water temperature change for the healthy aquaculture. In order to solve the problems of low precision and poor robustness of traditional forecasting methods, a short-term prediction model of water temperature in aquaculture pond was proposed based on BP neural network optimized by genetic algorithm, and pond aquaculture water temperature prediction system was designed and developed. Firstly, the principal component analysis (PCA) was used to ensure the factors that influenced the water temperature in aquaculture pond. Secondly, the genetic algorithm and BP neural network were integrated to optimize initial weights and threshold. The method not only can get optimal parameter, but also can reduce the errors generated by random initialization. Thirdly, the short-term prediction system was developed by using Java language based on B/S architecture. Finally, the system was applied in Yixing City, Jiangsu Province. Results showed that the mean absolute error (MAE), mean absolute percentage error (MAPE) and root mean square error (RMSE) from GA-BP neural network method were 0.1968, 0.0079 and 0.0592, respectively. It was clear that GA-BP neural network was better than BP neural network algorithm. The research result met the practical needs of the pond water temperature management.

Abstract:On account of the crown’s complicated structure and various forms, extracting the tree measurement factors of standing tree automatically, accurately and nondestructively is an important research subject in the forest survey. The three-dimensional (3D) point cloud data via 3D laser scanner was used as the study object. The 3D convex hulls construction algorithm based on computational geometry was presented to extract the crown surface area, crown projection area and crown volume automatically. In order to verify the accuracy of the algorithm, totally eight tree species and 120 standing trees were randomly selected for testing. The average relative errors of standing tree height, DBH and crown width were 2.33%, 1.10% and 3.92%, respectively. The relative average errors of auto computing for crown surface area, crown projection area and crown volume were 3.48%, 6.01% and 5.59%, respectively. 3D point cloud data via 3D laser scanner and 3D convex hulls construction algorithm could help to automatically and accurately calculate the values of these parameters which could not be measured accurately before, providing a reference for extracting the tree measurement factors of standing tree automatically via 3D laser scanner in the future. The proposed method had a practical prospect of application in the survey of forest resources.

Abstract:Study on tree DBH algorithm based on two-dimensional laser has engineering significance to forestry surveying. In order to solve the problem that the performance of algorithm can not be evaluated effectively when the trunk was taken as the measurement target. Five kinds of PVC tubes were scanned with laser scanning radar. Two kinds of geometric methods (tangent method and arc length method) and fitting method (Taubin), which are commonly used at present, corresponding four optimization algorithms were used to calculate diameter. The error and suitable range of the algorithm were analyzed and the performance of various algorithms was assessed. Results showed that Taubin algorithm had the highest precision, considering all samples the mean absolute error was 4.89%. It had the highest precision when measuring distance rang from 3m to 6m in which the mean absolute error was 3.62%. The errors of all calculation methods were relatively high when the pipe diameter was less than 200mm and measuring distance was less than 2m. The mean absolute error of Taubin method was 10.59%, the mean absolute error of optimized arc length method and tangent method were 14.03% and 13.47%, respectively. The accuracies of measured values of radius were greatly improved when measuring distance was further than 2m. The mean absolute error of the Taubin algorithm was reduced below 6%. Experimental results showed that the Taubin algorithm had the highest accuracy and stability in all methods, which was valuable for engineering applications.

Abstract:Straw mulching is one of the core techniques of conservation tillage, which can reduce soil erosion and improve soil water use efficiency. Some researchers believe that straw mulching is conducive to wheat growth, while some researchers repute that straw mulching could hinder winter wheat growth. In order to investigate the effect of maize straw mulching on winter wheat growth in North China region under double cropping area, a three-year (2014 to 2016) field experiment was carried out in Zhuozhou City, Hebei Province conservation tillage experiment land. The experiment was performed using randomized complete block design with three replications. A series of straw mulching were arranged in field experiment, including 5t/hm2（OM）, 4t/hm2（EM）, 3t/hm2（SM）, 2t/hm2（FM）, 1t/hm2（TM）and 0t/hm2 (NM), which was controlled trials. The effect of maize straw mulching on soil volume water content, wheat emergence rate, wheat leaf area index, maize root dry weight and yield were evaluated. The results indicated that there was a linear relationship between maize straw mulching quantity and soil water content, the soil water content was increased with the increase of straw mulching amount. The emergence rate of wheat was increased with the increase of straw mulching amount, and FM treatment got the maximum emergence rate. The wheat emergence under FM treatment was significantly higher than those under TM, NM, SM, EM and OM treatments, and the average emergence rate under FM treatment was increased by 6.9%, 10.0%, 11.9%, 23.8% and 33.7%, respectively, compared with those under TM, NM, SM, EM and OM treatments during the period from 2014 to 2016. The mean wheat LAI under FM, TM, NM, SM, EM and OM treatments was 5.3, 4.5, 3.6, 4.0, 3.3 and 3.0, respectively, in the whole wheat growing season during the period from 2014 to 2016. The maximum mean wheat root density of wheat under FM, TM, NM, SM, EM and OM treatments was 0.98cm/cm3, 0.95cm/cm3, 0.93cm/cm3, 0.93cm/cm3, 0.86cm/cm3 and 0.67cm/cm3, respectively, during the period from 2014 to 2016. The mean yield of winter wheat under FM treatment was increased by 2.94%, 7.56%, 7.91%, 11.50% and 13.53%, respectively, compared with TM, NM, SM, EM and OM treatments during the period from 2014 to 2016. Finally, it was concluded that appropriate amount of straw mulching (2t/hm2) could promote wheat growth and increase yield. The seeding rate should be increased and the qualities of notillage seeders should be improved, especially in anti-blocking device and sowing depth consistency. The research result can be helpful to the promotion of the technology of straw return in annual maize-wheat rotation cropping region of North China.

Abstract:Oxygation, which can impose aerated water to root zoon through Mazzei injector and subsurface drip irrigation (SDI) line, has been effectively overcoming problems associated with hypoxic soil environment induced by SDI and showing yield potentials and great application prospects. The objective of this study was to explore the impacts of oxygation under different irrigation levels and emitter depths conditions on soil aeration, plant growth, fruit yield and quality. Plot experiments were conducted in a greenhouse during tomato growing season (from Apr. 11, 2016 to Jul. 2, 2016) under the oxygation (O) and SDI (S) conditions with two different irrigation levels correlated with crop-pan coefficients (kcp) being 0.6 (W1) and 1.0 (W2) and two different emitter depths of 15cm (D1) and 25cm (D2), respectively. Consequently, there was a total of eight treatments (W1D1O，W1D1S，W2D1O，W2D1S，W1D2O，W1D2S，W2D2O and W2D2S) and replied three times, and the plots followed a randomized complete design. In order to assess the benefits of oxygation on soil aeration, variations of soil oxygen concentration (Os) and soil volumetric water content (θv) were investigated. Meanwhile, plant height, stem diameter, leaf area, yield of per plant and fruit weight at harvest were measured, and blooming date and the period of flowering were recorded, and the lycoypene, vitamin C, soluble sugar and organic acid contents of fruit were analyzed in order to study the impacts of oxygation on plant growth, yield and fruit quality. The results showed that oxygation appeared to improve soil aeration effectively accompanied with Os significantly increased by 6.42% (P<0.05) and θv decreased by 5.29%, compared with no-aerated SDI. Meanwhile, stem diameter and leaf area with oxygation were significantly 4.55% and 16.21% higher than SDI, respectively (P<0.05). On other hands, compared with SDI treatments, flowering was about 2 days later and the flowering period showed a tendency to prolong under oxygation conditions. What’s more, fruit dry weight in the biomass compositions was significantly increased by 23.57% and yield of per plant, fruit weight and water use efficiency with oxygation were significantly 29.07%, 23.93% and 28.11% higher than no aeration SDI, respectively. Thus, oxygation significantly stimulated plant growth and development, and then improved yield by controlling soil water-air ratio and ameliorating soil aeration. What’s more, compared with no-aerated SDI, the lycoypene, vitamin C and soluble sugar contents and sugar/acid ratio of fruit under oxygation conditions were significantly increased by 37.73%, 31.43%, 32.30% and 45.64%, respectively. Thus, not only fruit yield, but also fruit quality and taste benefitted from oxygation. On other hands, although increasing irrigation level from 0.6 to 1.0 also stimulated plant growth and development, and then increased fruit yield, lycoypene and soluble sugar contents of fruit were significantly decreased. In other words, yield increased with irrigation level increasing, but fruit quality declined. But the effects of irrigation level were less intensive than the positive effects of oxygation on fruit quality. What’s more, oxygation and increasing irrigation level interactively affected on yield. Thus, when all of fruit quality factors, plant growth and development and yield were considered together, combinations of oxygation and the 1.0 irrigation level (W2D1O and W2D2O) were the preferable treatments.

Abstract:Surface (0~7.5cm) soil water content (SWC) was measured at 82 locations in a typical alpine meadow ecosystem on the northern Tibetan Plateau by using time domain reflectometry for 14 times during the 2015 growing season to evaluate spatial variability and temporal stability of surface SWC. Results showed that the mean SWC of the two transects during the 2015 growing season was 26.0%. SWC had a weak variability in space and a moderate variability in time. The variability of SWC was increased with the increase of SWC. The spatial pattern of SWC at the 82 measuring locations had a weak similarity during July and early August and a strong similarity from middle August to early September. The mean relative difference (MRD) of SWC was from -11.5% to 8.5% and the mean standard deviation of relative difference (SDRD) was 8.6%. MRD was correlated with SDRD in a concave curve relationship. Index of temporal stability, mean absolute bias error, root mean square error and minimum-SDRD constant methods could all identify the best representative location and the accuracy of mean SWC estimation of the representative location was high. Comparatively, the minimum-SDRD constant method had a higher accuracy. This study can provide data supplement and method innovation for SWC study in alpine meadow ecosystems.

Abstract:The different soil bulk density levels (1.35g/cm3, 1.40g/cm3, 1.45g/cm3 and 1.50g/cm3) were constructed by indoor manual configuration. The experiment of water and fertilizer infiltration was carried out in the soil bin. The effects of soil bulk density on cumulative infiltration, wetting front migration, soil moisture, NH+4-N and NO-3-N transport were investigated. An empirical model was created, in which the cumulative infiltration amount and the wetting front migration distance were the dependent variables, and the bulk density and infiltration time were independent variables. Results showed that the soil bulk density had a significant effect on the cumulative infiltration, the migration distance of wetting front and the distribution and transformation of moisture and nitrogen in the soil. With the decrease of soil bulk density, the cumulative infiltration, wetting front migration, moisture in the body, NH+4-N and NO-3-N contents showed an increasing trend. The greater the soil bulk density was, the smaller the infiltration coefficient K became. The greater the soil bulk density was, the greater the infiltration index α became. At the same time, the average value, the change amount and the conversion rates of NH+4-N and NO-3-N in wetted body were increased with the increase of soil bulk density. The closer the distance to the emitter was, the higher the contents of NH+4-N and NO-3-N became. The distribution of NH+4-N in the moist body was mostly concentrated in the vicinity of the emitter. With the redistribution, the content of NH+4-N in the wetted soil and the conversion rate were decreased gradually, and the transformation amount was increased gradually. After the redistribution for 3d, 5d, 10d, 15d and 20d, with the end of irrigation time as the benchmark, the decline order was 2.34%, 11.41%, 34.22%, 59.06% and 73.75%, respectively. The distributions of NO-3-N in the soil were similar to water. After the redistribution for 3d, 5d, 10d, 15d and 20d, with the end of irrigation time as the benchmark, the NO-3-N content increase order was 0.76%， 60.12%, 156.95%, 204.68% and 180.51%, respectively. The soil bulk density had a significant effect on the distribution and transformation of moisture and nitrogen in the soil.

Abstract:Negative pressure irrigation technique, which is one of the new irrigation technology for saving water, was applied to substrate culture in greenhouse. There were fewer researches on the relationship between the daily consumption of tomato and meteorological factors added to the leaching link in substrate culture. The daily consumption of plant was affected by the interaction with meteorological factors and by the sensitivity of the meteorological factors. It was beneficial to develop the system of supplying nutrient solution and the management methods with substrate culture using negative pressure in greenhouse based on mastering above relationships. Tomato was used as a material with substrate culture testing for the condition of negative pressure to supply nutrient solution. The daily consumption of nutrient solution and meteorological factors, e.g., air relative humidity, air temperature and solar radiation intensity, were measured. Based on these factors, a multivariate regression model was established and the direct path coefficient, indirect path coefficient, determination coefficient and total contributions for estimating the reliability degree of the regression model were calculated by path analysis method. The results showed that the direct path coefficients of crop coefficient and daily average solar radiation intensity reached a very significant level (P<0.01). The determination coefficient of these two factors and the contributions to R2 among the factors were the maximum, thus the two factors were the important meteorological factors on daily consumption of nutrient solution for tomato.From the effect of meteorological factors reduction on daily consumption value by path analysis, it was indicated that the daily average solar radiation intensity was the strongest sensitive factors, followed by the crop coefficient and daily maximum solar radiation intensity.

Abstract:Ephemeral gully is a common erosion process and represents one of the significant watershed sediment resources in the hilly region on the Loess Plateau of China. A watershed with closure measures implement in Wuqi County, Shaanxi Province was taken as case study to quantify the relationship between the lengths of ephemeral gullies and eroded volume and assess the erosion rate in six years period. A total of 60 ephemeral gullies were surveyed under field conditions, and lengths of 245 ephemeral gullies were identified by two QuickBird images with the same time phase in years of 2007 and 2013. Results revealed that ephemeral gully density was 36.21km/km2 in 2013 and the total length of ephemeral gullies was changed from 13.74km in 2007 to 14.12km in 2013. Among 245 ephemeral gullies interpreted from images, the lengths of 46.94% gullies were decreased owing to connecting with gully heads with larger erosion rate or measurement error. Assuming that the cross section of an ephemeral gully is quadrangular frustum pyramid, the volume of 60 investigated ephemeral gullies was ranged from 0.4m3 to 15.43m3, which was 4.06m3 on average. Based on the built regression model, the volume change of 245 ephemeral gullies from 2007 to 2013 was 71.52m3. For 53.06% of ephemeral gullies with longer length than previous conditions, the average increasing rate was 0.2m3 per year for each growing ephemeral gully and the total increased volume was 157.51m3. The estimated erosion rate of ephemeral gullies was 67.31m3/(km2·a) on the 12 slope units with area of 0.39km2. The total eroded volume was about 100.97t/(km2·a) if the average soil bulk density was taken as 1.5g/cm3. Assuming that the average erosion rate of the other 46.94% ephemeral gullies was similar to those with increased length, the average erosion rate on the slope covered by herbal could be 215t/(km2·a). The results showed that ephemeral gully erosion rate could be estimated using very high resolution remote sensing such as QuickBird images, which could provide reference for the soil and water conservation on hilly Loess Plateau.

Abstract:Study on the effects of extreme precipitation events on runoff and sediment load not only can reveal the mechanism of runoff and sediment, but also provide important scientific support for basin disaster warning. Currently, there is limited information on the effects of extremes precipitation events on river sediment load. Thus, Songhua River Basin (SRB), located in the northeast of China was selected as study area, and daily precipitation data from 43 meteorological stations within and surrounding the SRB and sediment load from Kiamusze hydrologic station during 1960—2014 were collected. Seven extreme precipitation indices, including maximum 1-day precipitation (RX1day), maximum 5-day precipitation (RX5day), simple daily intensity index (SDII), strong rainfall more than 95% points value (P95pTOT), heavy precipitation (HP), rainstorm precipitation (RSP) and flood season precipitation (FSPTOT)) were chosen to quantify precipitation extremes. The Mann-Kendall’s non-parametric trend analysis method and wavelet periodic analysis method were used to analyze the dynamic change of precipitation extremes and sediment load. Double mass curve method was used to assess the effect of extreme precipitation events on sediment load change. The results showed as follows: there was no significant change trend of the seven precipitation extreme indices during 1960—2014;while there existed 16~20a main period and 5~6a minor period. Meanwhile, the change trend of sediment load in Kiamusze hydrologic station was similar with the precipitation extremes. The precipitation extreme indices had highly significant correlation with sediment load (p<0.01) in the SRB, among which correction between sediment load and RX5day and P95pTOT was the most significant. The abrupt change by double mass curve method indicated that the abrupt change point between sediment load and each extreme precipitation index occurred in 1977. Compared with the baseline period in 1960—1977, the effects of precipitation extreme indices on the sediment load were ranged from 3.09% to 15.24% in 1978—2014, in which the effect of SDII was the highest with 15.24%, followed by FSPTOT with 14.81% and RX5day with 14.34%. These findings would provide useful information for forecasting sediment disaster and taking measures in conserving soil and water in the SRB.

Abstract:In order to explore the water saving and efficient alkali-saline land pattern, the underground pipe drainage experiment was designed under the condition of drip irrigation to seek the effects of different buried spacings in the width of 15m, 20m and 25m on salt distribution in soil profile and the desalination and leaching. The results showed that soil salinity in 0~70cm soil layer was decreased significantly during the drip irrigation, and compared with CK the average salinity of soils was decreased by more than 10g/kg. Different spacing widths of 15m, 20m and 25m below 100cm soil layer indicated different maximum soil desalination rates, which were 86.47%, 84.79% and 81.35%, respectively, and the total desalination rate of soil was between 51.82% and 60.43%. The smaller the spacing of the buried pipe was, the larger the drainage flow in the drainage and drainage salinity and conductivity were, and thus the cost would be slightly higher. However, compared with 20m and 25m, the actual investment was increase by 8430 yuan/hm2 and 12570 yuan/hm2 in the spacing of 15m and the overall soil desalination rate was increased by 1%. When 15m spacing drainage pipes in the horizontal distances of 0m, 5m and 7.5m, the maximum soil desalting rate was 86.47%, 85.15% and 84.01%, respectively, and drainage flow, salinity and conductivity during drainage were 2m3/h, 189.15g/L and 35.9mS/cm, respectively. Besides, soil salinity leaching curve fitting effect was better than 20m and 25m spacing area, and overall level of soil layer below 70cm was fallen to below 10g/kg and crop growth conditions were greatly improved, which was suitable as a parameter for the layout of the underground pipe drainage pipe of Xinjiang saline soil. These results revealed that the drip evolution mode had great importance for the underground pipe drainage salinity, laied the foundation for the following long-term research, ultimately achieved improvement goals, and met the conditions for the growth of the crops.

Abstract:As an alternative water sources, piggery wastewater has attracted more and more attention. Study on piggery wastewater irrigation technology is essential for alleviating agricultural water resource deficit, reducing nitrogen fertilization and protecting eco-environment. Based on a field irrigation experiment in reinforced concrete lysimeters, the effects of piggery wastewater and clean water (equal nitrogen inputs) irrigation on soil NH+4-N and NO-3-N variations in time and profiles were studied. The inputs and outputs of nitrogen and the amount of nitrogen mineralization of different treatments were analyzed according to the principle of nitrogen balance. The results showed that the changes of soil ammonium nitrogen with time showed a similar trend to nitrate nitrogen, which had a peak in top-dressing stage at first, and then decreased. Ammonium nitrogen content was decreased with the increase of soil depth, but there was no significant difference in nitrate nitrogen. It can be easily leached and accumulated. Ammonium nitrogen and nitrate nitrogen were slightly decreased in PWH (piggery wastewater with high nitrogen) treatment after top-dressing stage, while the decrease range was more sharply in CKH (clean water and high nitrogen) treatment. PWH treatment was beneficial to the mineralization of organic nitrogen, and crop nitrogen uptake, nitrogen mineralization and nitrate nitrogen leaching amount in PWH treatment were higher than those in CKH treatment with values of 6.91%, 21.29% and 11.82%, respectively.

Abstract:As a kind of special landform unit, engineering accumulation is an important source of soil erosion. To explore effects of hedgerows on sediment particles fractal dimension on hillslope, and the runoff and sediment reduction effects of engineering measures, the field pouring water scouring experiments were designed for different inflow rates (35L/min, 45L/min and 55L/min) and slopes (24°, 28° and 32°) in six normal runoff plots (20m×5m). The results showed that the lagged time of initial runoff of hedgerow plots was 100~500s, and the runoff rate and sediment yield rate were less than those of the control plot. Runoff rate rose for intermittent fluctuations in time scale compared with the control plot. Hedgerow reduced the flow rate by 4%~60%, and decreased the rate of sediment by 15%~50%. Significant power function relationships of runoff and sediment reduction rate with slope and flow rate were observed, and the effect of sediment reduction was better than that of runoff reduction rate equation. Runoff sediment was dominant with silt particle, followed by clay. Compared with the control plot, the volume percentage of sand particle in sediment of the hedgerow plots was reduced. In contrast, the volume percentage of clay and silt was increased. Hedgerow plots clay enrichment rate was higher than those in the control plot, and the sand accumulation rate was less than the control plot. The fractal dimension of the hedgerow plots was bigger than that in control plots. The relationships between fractal dimension and the volume fraction of clay and sand were available for better fitting linear model, and fractal dimension of sediment erosion was mainly determined by the volume fraction of clay. The research results could provide some basic data for establishing the model of soil erosion of engineering measures under the condition of accumulation, and provide a theoretical reference for the optimal allocation to hedgerow slope.

Abstract:The artificial simulation rain experiment in field was designed to study the influence mechanism of polyacrylamide (PAM) on the process of runoff and sediment in four typical red soil slopes derived from different soil parent materials of South China under the condition of 140mm/h shortduration heavy rainfall. The experimental treatments included two kinds of PAM application rate of 2g/m2 and 10g/m2, which were expressed as PAM1200-2 and PAM1200-10, respectively. The results showed that the total runoff, unit sampling time runoff coefficient, cumulative sampling time runoff coefficient in each slope were increased significantly (p<0.01)， and the runoff with elevation order was quaternary red soil slope, red sandstone red soil slope, purple soil slope and granite red soil slope. The increase efficiency of runoff in the treatment of PAM1200-10 was more than that in PAM1200-2 treatment in different soil slopes except granite red soil slope. The increasing order of steady flow time was quaternary red soil slope (12min), red sandstone red soil slope (15min), granite red soil slope (24min) and purple soil slope (24min). There was no significant difference between the two kinds of PAM application rate (PAM1200-2 and PAM1200-10) in raising runoff yield. There was a significant decrease (p<0.01) in the total sediment, unit sampling time sediment concentration and unit sampling time sediment of each slope, the sediment reduction rate was the most remarkable in quaternary red soil slope with both of the two kinds of PAM application rate, there was slight difference in sediment reduction in red soil slopes derived from other three types of parent materials. The sediment reduction rate of PAM1200-10 was greater than that of PAM 1200-2 in different soil slopes, except purple soil slope. Among them, the sediment reduction rate of PAM1200-2 was more volatile than that of PAM1200-10. The sediment reduction rate of PAM1200-10 was relatively stable except the purple soil slope. In granite red soil slope, the effect of the sediment reduction of PAM1200-10 was significantly improved than that of PAM1200-2 (p<0.01).

Abstract:The energy structure of energy supply project always adopts traditional and renewable energy together for the past years. However, for the future development, renewable energy will gradually increase the proportion, or even completely replace the traditional energy. The actual energy supply engineering energy utilization effect is worthy of attention. There are two schemes to discuss: engineering test and software simulation. Engineering test will be time-consuming, while software simulation can save a great deal of costs, as well as carry out the design and verification of various control schemes. Therefore, the integrated solar-ground source heat pump for biogas digester heating system simulation was studied. The typical day and year energy utilization effects of the heating system were obtained by using TRNSYS platform with Type109-TMY2 (reader and meteorological data processor), Type71 (vacuum tube solar collector), Type60 (storage tank), Type3b (circulating pump), Type60c (methane), Type668 (heat pump), Type557b (buried pipe), Type14h (operation controller), Type25a (print results) modules. Results showed that in the typically coldest winter day, the total heat supplying capacity was 225.52MJ/d, which included heat pump power consumption (57.24MJ/d), water pump power consumption (13.39MJ/d), buried tube (71.93MJ/d) and solar collector (82.96MJ/d). The total heat dissipation capacity was 208.57MJ/d, which contained biogas pool maintenance structure heat (132MJ/d) and liquid heating load (76.57MJ/d). The annual total heat consumption of the system was 46657.32MJ, the renewable energy included solar contribution (63%) and geothermal contribution (37%), which accounted for 74%. It showed that renewable energy sources were efficiently utilized in the heating system. Furthermore, the system can store 7630.99MJ/a of heat to the ground but the heat absorption capacity was 12954.81MJ/a. Although the heat storage capacity cannot meet the demand of heat supply, it can alleviate the cold and hot imbalance of soil to some extent.

Abstract:It is an attempt to characterize of the oxygen penetration depth at the particles scale during chicken manure digestate co-composting wheat straw by Fourier transform infrared microspectroscopy (FT-IRM). It is presented to improve the anaerobic/aerobic co-process mechanism, in order to ensure adequate oxygen supply. The spectral range, spectral resolution and pixel dimensions in the transmission spectra were 750~4000cm-1, 16cm-1 and 6.25μm×6.25μm, and a mean spectrum of 8 scans was used for the second-derivative analysis with nine smoothing points. Chicken manure digestate aerobic composting samples by freeze-drying treatment should be made into 12μm slice by using paraffin section technology. Selection of 2856cm-1, 1640cm-1 and 1568cm-1 , 3001cm-1 was done to represent aliphatic component and aromaticity, respectively, which were used for deciding the boundary of oxygen penetration depth. The difference curve drops rapidly was regarded as the terminal point of oxygen penetration depth. The oxygen penetration depth of chicken manure digestate particles fluctuated within 7~20μm, which was lower than that of pig manure aerobic compost particles. The variation in the oxygen penetration depth can be described by an exponential fitting function. The results indicated that it was feasible to determine the oxygen penetration depth of aerobic composting particles by FT-IRM, but the method and technical parameters should be selected according to the characteristics of different materials.

Abstract:In order to reduce the data transmission and energy consumption of sensor nodes and improve the broadband utilization and life cycle in real-time cold chain logistics monitoring system for agri-food based on wireless sensor networks, a clustering fusion method based on arithmetic mean and batch estimation for the cold chain temperature monitoring of agricultural products was proposed, Firstly, the mistake errors of the collected data was eliminated, and then the data which were sent from the cluster member nodes were merged by the mean and the batch estimation method. Secondly, the cluster head node used the adaptive weighting algorithm to further analyze the fusion data of the member nodes. The experimental results showed that the network lifetime of the cold chain monitoring system based on the data fusion method was 34.2% higher than that of the traditional method, and the stability period was 11.4% higher than that of the traditional low power adaptive cluster clustering protocol. Compared with the traditional arithmetic average method, the accuracy of data fusion was improved by 7.6%, the system energy consumption was decreased by about 32.5% per round, which can not only reduce the influence of redundancy and less reliable data on the measurement results, but also reduce the unnecessary data transmission loss, as well as reduce the cost of cold chain logistics and improve the degree of informatization of cold chain logistics to a certain extent.

Abstract:Phase change materials (PCMs) have been a main topic in research in recent years, but although the information is quantitatively enormous, it is widely spread in the literature. The storage of latent heat in organic matters could provide a great density of energy storage with a small temperature difference between storing and releasing heat. Six kinds of organic matters, including tetradecane, lauric acid, methyl laurate, decanoi, decanoic acid and ethyl salicylate were selected as experimental materials for development of phase-change coolant for non-freezing cold chain. The thermodynamic formula was used to calculate the onset temperature and latent heat of designed compounds. DSC and stability tests were used for the selected compounds with the appropriate onset temperature and high latent heat. DSC was used commonly and it was the most authoritative method of determining phase change properties until now. The results showed that decanoic acid/methyl laurate, decanoic acid/decanoic, lauric acid/tetradecane, methyl laurate/lauric acid had onset temperature range of 0~4℃, latent heat of 150~210J/g, which met the requirement of non-freezing cold chain at low temperature. In these PCMs, lauric acid/tetradecane (mass ratio 3.12∶96.88) had the optimal performance, with onset temperature of 4.03℃ and phase change latent heat of 207.05J/g;lauric acid/tetradecane (mass ratio of 6.17∶93.83) and decanoic acid/tetradecane had a good performance in thermal properties and cost, with onset temperature of 3.89℃ and 3.19℃ and phase change latent heat of 192.61J/g and 189.21J/g, respectively;decanoic acid/decanoic (mass fraction of decanoic acid was 34.51%~47.24%) was selected for its relatively wide range of adjustable onset temperature. The above PCMs owned broad application prospects.

Abstract:With the aim to validate and accurately evaluate the applicability of time-temperature indicator (TTI) application at variable temperatures, a prediction method based on the fuzzy reasoning was built. The method was on the basis of quality experience equation of the monitored products at constant temperature experiment, which could be chosen from polynomial equation, the n-th reaction kinetic equations or other equations according to the fitting coefficients. The key of this method was to build exact membership functions between arbitrate effective temperature and the constant temperature in order to obtain the predicted value at arbitrate effective temperature. The method was analyzed about Muscat Hamburg grape, Vitsab M25-2 and OnVu TTI through two fluctuant temperature experiments simulating temperature characteristics of table grape cold chain logistics. Triangle membership function was chosen in the prediction based on the fuzzy reasoning. The table grape quality predicted values based on the fuzzy reasoning and the kinetics model were compared with the actual measured values. Results showed that the TTI prediction method based on fuzzy reasoning at low fluctuant temperature made improvements (6.03 percentage points and 2.70 percentage points) vs TTI prediction method based on the reaction kinetics equations, whereas made no improvements at high fluctuant temperature. Therefore, TTI prediction method based on fuzzy reasoning could be chosen at low temperature based on the principle of merit.

Abstract:The liquid-solid transition of low acyl gellan (LA) and sodium caseinate (SC) mixtures were investigated by using rheological measurements. The liquid-solid transition temperatures were determined from two criteria: the crossover of storage modulus G′ and loss modulus G″, and the Winter’s criterion. The results showed that the Winter’s criterion was more suitable to determine the sol-gel transition temperature. For LA/SC mixtures, there was a critical SC concentration (0.005g/mL ratio of mass to volume). The concentration of sodium caseinate almost had no influence on the gelation temperature of LA/SC mixtures at or below concentration of 0.005g/mL. While above 0.005g/mL, the gelation temperatures of LA/SC mixtures were decreased linearly with the increase of SC concentration. The relaxation critical exponent n can be determined by the Winter’s criterion. There was no universal n for the gelation in LA/SC mixed solutions, indicating that this gelation belonged to the cross-linking of existing macromolecules. And n increased with the increase of SC concentration until SC concentration reached a critical level, after which further increase in SC concentration resulted in a reduction of n. The fractal dimension df was calculated from n without the screened hydrodynamic interaction or the excluded volume effect and the trend of the change of the df was opposite to that of n. Using a non-isothermal kinetics model, active energy (Ea) during gelation was calculated. However, a discontinuity was observed in the activation energy plots. Based on this, two gelation mechanisms were presumed-association of low acyl gellan gum and sodium caseinate molecules and aggregation of polymer strands.

Abstract:Pseudomonas spp. is the main bacteria involved chicken degradation which ultimately affects the meat quality and the potential of posing health public health threats. The use of near infrared spectroscopy (NIRS) for rapid identification and monitoring of four strains of Pseudomonas spp. in degrading chicken was attempted. Initially, four Pseudomonas strains namely Pseudomonas gessardii, Pseudomonas psychrophila, Pseudomonas fragi and Pseudomonas fluorescens were isolated from samples of degrading chicken and identified via polymerase chain reaction (PCR) technology. The different isolated Pseudomonas spp. were cultured in trypticase soy broth (TSB) and incubated at 30℃ for 12 h to growth. The four isolates of Pseudomonas spp. and their combined mixture in equal proportions were all prepared from the incubated inoculum by using 100mL∶5mL and each replicated 40 times. The preprocessed data outcomes of the 200 samples using standard normal variable transformation (SNV) exhibited superiority compared with other deployed data preprocessing algorithms such as multiplicative scatter correction (MSC), calibration standard score, first derivative (DB1) and second derivative (DB2). Synergy interval partial least squares (SiPLS) was employed to select relevant characteristics wavelengths such as 3999.64～4597.46cm-1, 6406.37～7004.19cm-1, 8211.41～8805.38cm-1 and 8809.24～9403.20cm-1. Principal component analysis (PCA) was performed prior to the model development with loadings of 97.02% in PC1, 2.47% in PC2 and 0.27% in PC3 which indicated the possibility of developing models for the classification of the different samples of Pseudomonas spp. The recognition rates for KNN (65.00%, 63.75%), SVM (91.67%, 86.25%) and BP-ANN (99.17%, 95.00%) were obtained in the training and prediction sets. The model results obtained for SVM was sufficiently high and may be combined with NIRS system for the possible Pseudomonas spp. classification. However, the best result was obtained with BP-ANN built model. These high recognition rates implied near-infrared spectroscopy combined with BP-ANN can be deployed for the rapid detection of different Pseudomonas spp. strains in chicken for the purpose of safeguarding its deteriorating chicken quality.

Abstract:Enzyme-assisted aqueous extraction processing (EAEP) is an alternative method to extract oil which is safer and more environmental-friendly. EAEP results in four fractions: free oil, oil-in-water emulsion, liquid fraction (skim), and residual fraction. The surplus amounts of residual are the limitation of EAEP. The residue contains a large amount of fiber. EAEP residue fiber based edible films containing citric acid and glycerol was prepared. In the single-factor experiment, the effect of citric acid concentration, glycerol concentration, crosslink time on the tensile strength, elongation at break, water vapor permeability of EAEP residue fiber based edible films was studied. In order to optimize the process parameters and investigate the interrelationship between the three factors and water vapor permeability, response surface methodology was employed. Results indicated that the water vapor permeability was influenced the most by glycerol concentration, crosslink time and the least by citric acid concentration. The optimum conditions were as follows: citric acid concentration of 20%, glycerol concentration of 36% and the crosslink time of 5min. Under the optimum conditions, the water vapor permeability of the EAEP residue based edible film was 1.81g·m/(h·Pa·m2). The scanning electron microscopy showed that the edible film prepared under the optimum process conditions had a relatively smooth surface. The infrared spectrum analysis indicated that crosslink may have taken place between citric acid and the fiber of EAEP residue. Glycerol may affect the reaction between citric acid and the fiber. The results can provide a reference for the production of EAEP residue based edible film.

Abstract:The precision of linear pressure control of solenoid valve, which affects the response precision of hydraulic control in regenerative braking system, is related to the control characteristics of solenoid valve and PV characteristics of wheel cylinder. The control method of linear pressure control of solenoid valve based on PV characteristics of wheel cylinder was proposed. The working principle of the solenoid valve was analyzed, and the demand of control precision of the solenoid valve was given. By analyzing the control mechanism of the solenoid valve, it was pointed out that the linear pressure control of solenoid valve had a linear control range, and it can be also realized by increasing the coil current. By analyzing the PV characteristics of the wheel cylinder, it was pointed out that the wheel cylinder had nonlinear characteristics in low pressure region and approximate linear characteristics in high pressure region. The characteristics of the wheel cylinder pressure changing rate at different current changing rates were analyzed, and the linear pressure control algorithms of the low pressure region and the high pressure region were proposed respectively. dSPACE platform was used to build hardware-in-the-loop test bench, different pressure changing rates of wheel cylinder were tested, which can observe the following results between actual pressure and target pressure. The experimental results showed that the proposed linear pressure control algorithm can satisfy the requirement of the control precision of the solenoid valve, and enrich the linear pressure control theory.

Abstract:In view of the problem that the energy consumption of interconnected suspension is too large and the vibration energy of the suspension cannot be recovered, a new type of hydraulic interconnected power system was presented, which can improve the dynamic performance of the whole vehicle and recover the vibration energy of the suspension. Compared with the passive interconnected suspension, the hydraulic interconnected energy regeneration suspension structure adopted the hydraulic motor to replace the damping valve. The hydraulic rectification bridge was used to rectify the pipeline. On this basis, a constant current control feed circuit was designed. On the one hand, it can be used to recover and store the suspension vibration energy. On the other hand, the constant current value also can be changed to improve the dynamic performance of the whole vehicle. The structure and working principle were introduced, the AMESim dynamic model was established, and the constant current feed energy circuit of the hydraulic interconnected power supply system was designed. A preliminary study on the dynamic performance of the input excitation in sinusoidal and random pavement was studied. On the basis of this, the bench test was carried out，and the experiment and simulation results were basically consistent. Results showed that compared with the hydraulic interconnected energy-regenerative suspension without the control of constant current circuit, the hydraulic interconnected energy-regenerative suspension with the control of constant current circuit had a better overall dynamic performance, the angle acceleration and the vertical acceleration of the vehicle body were decreased, and the recovery of the vibration energy of the vehicle body was realized, which provided a theoretical basis for the mode switching control of the hydraulic interconnected energy-regenerative suspension.

Abstract:Based on magnetoelastic effect, the magnetic circuit of the draft sensor, which was used in electro-hydraulic lifting mechanism of high-power tractor, was learned and designed. According to the analysis of the working condition and the structure of the same type product abroad which used a columnar excitating magnetic core to create the working magnetic field, a new kind of magnetic structure was designed, which changed the excitating magnetic core from columnar to cruciform, so that changed the mechanical dimensions from 2D to 3D. For the design, bear force from horizontal and vertical directions in the same time, which resulted in the shear deformation in both directions, it also made greater change of the magnetic field, and it is more comfortable under actual working conditions. The 3D model was built to show the structure of the draft sensor with cruciform excitating magnetic core, and the mathematical model was built, which could describe the operating principle and working process of the magnetic circuit in detail. Then according to the mathematical model, the simulations of two kinds of draft sensor were made by Matlab/Simulink. By comparing the two simulations, the result showed that the linearity of this new design with a cruciform excitating magnetic core was changed from 1.85% to 0.08%. And the sensitivity was changed from 0.09mV/kN to 0.21mV/kN, which proved that the new design of draft sensor with cruciform excitating magnetic core was more suitable for the force measurement and control of electro-hydraulic lifting mechanism under the condition of heavy load, which can be more adaptable for bad working environment to improve the tillage effect.

Abstract:Traditional direct-drive proportional directional control valve is usually actuated by the proportional solenoid. However, it is very difficult to improve the flow，because of the magnetic saturation of the proportional solenoid itself. Therefore, a new 2D electro-hydraulic proportional directional control valve was proposed. A new ball-screw type axial compression and torsion coupling as an important part was designed in this valve, which was used to amplify the driving force of the solenoid. In the theoretical analysis, the amplification coefficient was 20. It was to overcome the friction force and clamping force or other nonlinear factors. The experimental results showed that the larger helix angles and the force transfer radius of the compression and torsion coupling were, the more obvious the effect of pressure-torsion was;changing of flutter amplitude compared with flutter frequency obviously improved the static characteristics of the valve;the static characteristics of the valve were improved obviously with the increase of the helix angle and the force transfer radius. Under pressure of 7MPa, the maximum hysteresis of the valve did not exceed 3%, and the dead zone was about 0.5%;under pressure of 28MPa, the flow rate was up to 190L/min, the dead zone was about 2.8%, the maximum hysteresis was less than 5%, and pilot level leakage was about 0.2L/min. The theoretical analysis and experimental data indicated that the valve had good static characteristics compared with the traditional valve and practical engineering applications.

Abstract:A kind of 2-DOF spherical parallel mechanism was presented. Based on the mechanism, a type of wheel-legged mobile robot was developed, which had a simple structure and a good obstacle climbing ability. According to the design theory for parallel mechanisms based on position and orientation characteristic equation and the principle for the coupling degree reducing, a novel 2-DOF spherical parallel mechanism was proposed. The inverse kinematics, workspace, velocity and acceleration model of RUPU-RUPR spherical parallel mechanism were modeled by using analytic geometry method and closed loop constraint equation. The workspace, velocity and acceleration solutions were verified by numerical methods. The dynamic equations of RUPU-RUPR spherical parallel mechanism was also established by Newton-Euler formulation. Given the platform moving rules and external forces, the driving torque of the RUPU joint and the constraints torque of the RUPR joint were calculated. A simulation solution of the dynamic model was given. The results illustrated that the spherical parallel mechanism had a simple mechanical structure and large workspace. The research provided a theoretical base for its kinematics and dynamics and workplaces of this spherical parallel mechanism.

Abstract:A new method of solving inverse kinematics of 6R welding robot based on radial basis function（RBF） neural networks was presented to improve the precision of the position and orientation and the accuracy of welding trajectory for the 6R welding robot. The inverse kinematics solution prediction model of the 6R welding robot was established based on RBF neural networks because the inverse kinematics equations were high-dimensionally nonlinear and solving these equations was complex. The work space in which 6R welding robot position and orientation sample parameters were situated was divided based on scale-space theory. After that the training sample set was selected optimally based on uniform design and the cluster theory. The parameters were transformed and normalized according to the Z-Y-Z coordinate conversion principle. The problem of solving the inverse kinematics equations was transformed into six inputs and six outputs prediction system based on RBF neural network. Complex movement trajectory of 6R robot was simulated and the spot welding experiments were done by means of this prediction system. The results of the prediction and welding track accuracy were compared with the inverse kinematics solution based on combinatorial optimization iteration algorithm and back propagation (BP) neural networks. The results showed that the RBF prediction model of solving 6R welding robot inverse kinematics equations was simpler, more accurate and easier to do trajectory planning, and it was proved to be feasible and effective.

Abstract:To satisfy the health monitoring requirements of the on-state magneto-rheological (MR) semi-active suspension shock absorber and improve the reliability of the damping system, a piezo-resistive acceleration sensor integrated with MR absorber was designed to measure the dynamic acceleration. According to the characteristic of shock absorber and the piezo-resistive acceleration sensor, the concept of integrated acceleration sensor was proposed. Then the design principle of the integrated piezo-resistive sensor was analyzed. Structure selection of the chip was determined on the basis of the principle. In order to ensure the high sensitivity and good dynamic characteristics of the sensor, the main dimension parameters of chip were derived by theoretical analysis and finite element method while the testing range was set as one of the constraints. The layout of the chip, the width and length of the resistor were designed based on the theoretical analysis. Based on the finite element method analysis, the transverse sensitivity was smaller than the vertical sensitivity. Comparing with the vertical acceleration, the effects of transverse acceleration can be ignored. The maximum yield force appeared at the root of beam. Referring to the design requirements, a piezo-resistive acceleration sensor was designed. The single degree of freedom MR suspension with the MR damper integrated acceleration sensor was tested under the sine and random signals. The results showed that the designed acceleration sensor had good precision and dynamic stability which can satisfy the application requirement.

Abstract:LEMs achieve the movement and force transmission through flexure hinges, so it is very important to design flexure hinges. A new type of flexure hinge based on double C-type structure was proposed, named as DCA-LET flexure hinge. The characteristic parameters influencing the performance of the flexure hinge were defined. Based on the simulation analysis of eight examples of different characteristic parameters, the fitting curve of the relationship between the characteristic parameters and the simulation values of the equivalent stiffness was obtained. The theoretical formula of equivalent spring stiffness based on the characteristic parameters of the hinge was deduced and the correction factor was introduced. The correctness of theoretical calculation formula and correction factor was verified by theoretical calculation and finite element simulation of three examples. The bending and tensile properties of three DCA-LET flexure hinges with different characteristic parameters and inside LET flexure hinge were compared, and the results showed that the DCA-LET flexure hinge had better overall performance than the LET flexure hinge. The characteristic parameters can control the bending performance of DCA-LET hinge, and its tensile and compression properties had no significant decrease, which provided an effective method for the design of the flexure hinges.

Abstract:Traditional pump-controlled differential cylinder technology has problems such as complex hydraulic circuit, slow response and high energy consumption. Based on this, a combined control method of displacement and speed was proposed to directly control the differential hydraulic cylinder by using a variable servo pump. Firstly, differential cylinder combined control system was divided into three subsystems based on theoretical analysis of pump-controlled differential cylinder principle. Secondly, the model of the system in which the inner-loop controlled displacement and outer-loop controlled speed was established for simulation. Response speed under hybrid control had better dynamic characteristic than that under constant speed. Thirdly, the test platform was set up for experimental analysis of pump-controlled differential cylinder. The dynamic response of differential cylinder controlled by the system in which the inner-loop controlled displacement and outer-loop controlled speed was faster than that controlled by the system of constant speed, which reduced the time by 13.4%. Under constant pressure mode, the input energy consumption of serve motor was measured. After comparative experiments under different speeds and pressures, the system energy consumption under low speed and large displacement was decreased by 3kW. Simulation and experiment results showed that the response speed of pump-controlled differential cylinder was improved and the energy consumption was reduced effectively under the combined control mode of displacement and speed.