Abstract:In China, agricultural production still mainly based on manpower, while agricultural labor population continuously declining, low agricultural resource efficiency, average agricultural resource shortage, low average age of new generation farmers and population aging in practical agricultural labor are the main troubles in developing agriculture. Research of intelligent devices and models to realize precise agriculture is a criticle approach to solve the problems and realize modernlization agriculture in China. IoT (Internet of things) in agriculture is an advanced technology aims at digging agricultural productivity potential, intelligentize agricultural equipment and realizing intelligent production, it includes agricultural information perception, agricultural information transmission and intelligent information processing technologies, IoT in agriculture focusing on applying in field planting, facility horticulture, livestock feeding, aquaculture and agricultural products logistics according to individual requirements. The progress of IoT in agriculture was concluded in last three years, which mainly focused on important breakthroughs of agricultural individual identification technologies, agricultural sensing theories and crafts, low-power wide-area network (LPWAN) technologies, agricultural big data technologies and artificial intelligent technologies. A framework of IoT in agriculture was proposed that agricultural operational control was based on agricultural operational models and self managed device network, according to the framework, the role of human was consumer of real-time data and valuable information, the labor output was based on IoT drived intelligent equipment. Furthermore, restriction factors were summarized by contrasting IoT applications in China and in advanced agricultural countries, the development strategy was raised for the development of IoT in Chinese agriculture, and finally the perspectives and main research issues of IoT were concluded in Chinese agriculture.

Abstract:In order to realize the function of tractor cruise control system, the tractor acceleration was controlled precisely. Due to the non-linear, road slope and vehicle quality changes caused by longitudinal dynamic system tractor mounted implement, wind resistance and other external interference factors existing, the control system robustness become the focus of the controller design. The longitudinal dynamic model of the tractor was established by using modular mechanism modeling methods and combining with the experimental data, and this model was realized in Simulink, compared with the real vehicle platform, the validation of the model met the demand. According to the nonlinear characteristics of the tractor longitudinal power transmission system, the longitudinal dynamic model of the tractor was linearized by the inverse model method. Based on the linearized model, the frequency response characteristic data of each working point and the working condition of the lower control object were obtained. The transfer function of the lower level object was identified by the frequency response experiment and the least square method. According to the transfer function and the nonlinear characteristics of longitudinal acceleration response, a sliding mode variable structure controller was designed. Compared with the PID control, the simulation results showed that the controller can effectively improve the robust performance of the system to nonlinear characteristics and external disturbances.

Abstract:The pure pursuit model is widely used in the path tracking control system of agricultural machinery. However, system oscillations occur easily at high speed. Aiming to improve the stability of the trajectory tracking system of automatic rice transplanter, a path tracking method based on fuzzy control was proposed to adjust the lookahead distance of pure pursuit model. Firstly, the kinematic model of the transplanter was established by considering the automatic steering system as firstorder model. Secondly, by linearizing the kinematic model, the stability condition of pure pursuit model was analyzed while tracking a straight line. Based on the stability condition, fuzzy control model was established to adjust the lookahead distance of pure pursuit model, with taking the speed and lateral deviation as inputs and the lookahead distance as output. To construct the experimental platform, automatic transformation was carried on with Yanmar VP6E rice transplanter. Finally, to verify the availability of proposed method at different speeds, the experiments were carried out at high speed of 1.0m/s and low speed of 0.3m/s. Compared with the traditional pure pursuit model with fixed lookahead distance, the method proposed can avoid oscillation at high speed and track the target path quickly at low speed. It was proved that this method can effectively improve the stability of the pure pursuit path tracking system.

Abstract:Aiming at mechanized picking of litchi fruits with low damage and high efficiency, an end-effector integrated clamping and cutting of litchi picking robot with single power source drive was designed firstly. Secondly, the cutting mechanical model and the stabilized clamping mechanical model of the litchi serial fruit mother branch were constructed. Thirdly, the force sealing of clamping module was analyzed, on this basis, the normal pressure computation model of stabilized clamping with three points contact was derived. At last, the physical prototype of end-effector was manufactured and the work performance tests were executed. The performance tests included picking test, load test and anti-occlusion interference test. The experiment results indicated that the litchi picking end-effector well preformed in weight clamping with maximum dynamic weights of 1.33kg and 3.01kg when the diameters of fruit mother branches were 3mm and 7mm, respectively. What’s more, the litchi fruit was stably clamped and the branch was cut quickly when picking with average time of clamping and cutting of 2s. The success rate was 100% when the diameters of the fruit mother branches were lower than 5mm. The average success rate was 70% when the diameters of the fruit mother branches were between 6mm and 7mm. Besides, the end-effector had medium picking ability of antiocclusion interference.

Abstract:In the past, spatial feature extraction of hyperspectral image was usually limited to one feature extraction, and the more comprehensive spatial feature was not obtained. An improved scheme was put forward according to existent methods. An algorithm of classification (BFRF-SVM) was proposed, which was combined with spatial information obtained by Beltrami flow and domain transform recursive filter. Firstly, the spatial feature was extracted by Beltrami flow on hyperspectral data whose dimensions were reduced by principal component analysis (PCA), and the spatial correlation feature was obtained by domain transform recursive filter for all bands. Secondly, the two kinds of feature were combined, which were classified by SVM. The BFRF-SVM classification method was implemented on the hyperspectral data of Indian Pines and Pavia. The following results were obtained. In the first place, the overall accuracy (OA) of Indian Pines was 96.01% and that of Pavia was 97.46%, which were 12~15 percentage points higher than that of SVM, 12~16 percentage points higher than that of PCA-SVM, 2~12 percentage points higher than that of SGB-SVM, SBL-SVM and SGD-SVM, 4~5 percentage points higher than that of EPF, 1~3 percentage points higher than that of IFRF, and 2~6 percentage points higher than that of SMP-SVM, respectively, showing very good performance in hyperspectral classification. In the second place, although the training samples were only 7% of Indian Pines and 3% of Pavia, the OA of both can reach 96.01% and 97.46%, respectively, which removed the salt and pepper noise in the classification map obviously. In the last place, although the training samples were reduced to 4% and 0.5% for Indian Pines and Pavia, the OA can be over 91% and 90%, respectively. When the training samples were increased to 10% and 4.5%, the OA can exceed 97% and 98%, respectively. The effectiveness of BFRF-SVM was fully verified in the hyperspectral classification with good stability. The experiments showed that the BFRF-SVM algorithm was better than original SVM with the pure spectrum information, dimensionality reduction, the spatial-spectral information, the method of edge-preserving filtering and recursive filtering, and the morphological feature based method. The performance of hyperspectral image classification algorithm, i.e. BFRF-SVM, was greatly improved, and the effectiveness of the method was fully verified. The method can be applied into the field of classification and identification for agriculture and forest.

Abstract:Yellow feather chicken is a kind of traditional poultry in China. In recent years, labor shortages and diseases are two factors that affect production and health of yellow feather chicken. Using machine vision instead of manual monitoring of chickens and rapid identification of diseased chickens is a new research direction to solve the plight of poultry breeding. The symptoms of a diseased chicken mainly occurred in the eyes and comb which were mainly in the head. A method to recognize diseased chickens based on the head features was proposed. At first, totally 500 images of the healthy chickens and 236 images of the diseased ones were separately captured from the videos taken in the actual feeding environment composed the graphic base for the experiment. From each image, 10 chicken areas with 10 pixels×10 pixels, three comb areas with 5 pixels×5 pixels and 10 background areas with 10 pixels×10 pixels were selected to form the sample sets. The R,G,B and H component values of each pixel in the sample sets were obtained to get color difference threshold of the background and H threshold of the comb and chicken. Segmentation of the yellow feather chicken could be completed by using the color difference threshold for removing the background and the H thresholds for the object regions. Combs and eyes and their contours were also obtained in HSV color model by the H threshold. Then distance d1 between any two points on the different contours of the combs was calculated. The points if d1 was less than the maximal side of the external rectangle of each comb were connected to make the two combs to be a whole. The external rectangle of the connected combs included the chicken head. A correcting method was to extend this external rectangle to both sides until the width of the rectangle was larger than the height to improve the integrity of the chicken head recognition. Co-occurrence matrix of H component was calculated from the comb to get the color feature and the texture feature including ASM，COR，IDM，Ent 6 geometry features including A，P，R，E，C and A/P were computed from the eye contour. All these 10 features formed characteristic vector of the chicken head. Average recognition accuracy (ARA) was adopted to select the best feature set (ASM，Ent，E and A/P). At last, SVM was trained by 420 healthy images and 200 diseased images, and then tested by 80 healthy chicken images and 36 diseased chicken images. Accuracy of the identification of diseased ones was 92.5%. The test results indicated that the proposed method was feasible and valuable to identify diseased chickens by head features using machine vision.

Abstract:To replace the high-intensitive manual paving work of substrate for elevated cultivation，an automatic mobile paver was developed. This paver can realize the integration operation of inter-row substrate transporting, in-bin upward discharging, double-sided blanking and evenly paving. It was found by measurement that inter-row road was too narrow to vehicle driving. And both width of inter-row road and height of elevated cultivation bed had fairly big errors, so profiling paving operation was necessary. It was found from test of substrate flow characteristic that static accumulation angle of the substrate was about 37° and the sliding angle was about 40°, it was easy to cause conical piling in binning operation, arching in in-bin discharging operation and blocking when filling into bed. Therefore, an integrated automatic mobile substrate paver with tiny telecontrolled intervention was developed to fulfill the task of mobile double-sided floating paving operation for elevated cultivation. The in-bin L-type scraper upward discharging unit, double-sided floating blanking unit, bed-edge profiling paving unit and other key components were designed, and parameter optimization of key components, parameter matching and motion coordination of different components were performed. Test results indicated that this prototype can enter the inter-row road and start mobile double-sided paving by remote control, and then perform all coordinated actions automatically. It can guarantee the compensation of 100mm height error and 40mm width error of cultivation bed in double-sided profiling paving, and the working efficiency reached 330m2/h. Relative errors of in-bed substrate depth were 7.72%, 6.75%, 9.33% and 9.66%, respectively, and substrate depth difference among four beds was only 2.01mm, which indicated that equational and stable paving was achieved. This development may provide a good equipment support for mechanized production of elevated cultivation.

Abstract:Under the influence of medium and high power tractor driving the sowing machine, high-speed precise seeding technology has become an important direction of corn seeder development. So the corn metering device which is the core component of corn seeder attracted many experts and scholars to study. And the results dedicates that the existing pneumatic metering device existed inaccurate sowing precision and the mechanical metering device owns poor adaptability for high-speed operation. According to the above practical problems, a declined disk corn metering device was designed which owned advantages such as simple structure and good seeding performance. The declined dick metering device used angle strengthen sufficient effect and type hole plate to reduce the damage of seeds. The key parameters such as the inclination of the seed metering device and the main structure of the type hole plate were analyzed and determined. Based on the results of the orthogonal rotational combination experiment on the metering device test bed JPS-12, the performance of the metering device was analyzed and the regression equation was obtained between working parameters (the declination angle, number of the type hole, velocity of the type hole plate) and metering performance index. Then the optimized calculation was carried out. According to the optimization results, the speed adaptability test was carried out, the results showed that when the declination angle was 39°, the number of type hole was 30, the speed of the plant was 8.2~11.9km/h, the metering device qualified rate was more than 90%, the leakage rate was less than 3% and the replanting rate was less then 8%, which could completely meet the requirement of technical specifications of quality evaluation for drills in China.

Abstract:As people pay more and more attention to food safety issues, chemical weeding is increasingly limited. Compared with chemical weeding and artificial weeding, mechanical weeding has the advantage of less pollution and high efficiency, which conforms to the trend of sustainable agricultural development. However, the traditional cultivation can only remove interstage weeds and cannot remove weeds between plants. In order to meet the requirements of mechanical intra-row weeding for maize in China, a cam rocker swing intra-row weeding device was designed. The overall structure and working principle of the weeding device were illustrated and analyzed. The key components of weeding device were designed, such as the cam rocker mechanism and the weeding knife. The factors that affected the effect of weeding were got based on the kinematic and force analysis of weeding device. For the performance of weeding device, the forward speed, spring stiffness coefficient and weeding knife rotating speed were taken as experimental factors, and weeding rate and injury rate were taken as test indexes. The orthogonal test L9 (34) was conducted in the indoor soil bin for getting test factors affect the performance of weeding device work. Test results showed that the order of the various affecting factors were the spring stiffness coefficient, forward speed and weeding knife rotating speed;the best combination was as follows: the spring stiffness coefficient was 60 N/mm, forward speed was 0.6m/s, weeding knife rotating speed was 130r/min. To the optimal level combination of verification experiment: weeding rate was 89.8%, and injury rate was 2.1%.

Abstract:Aiming at the problems such as serious soil adhesion, large traction resistance, a press device in mechanical type reducing adhesion and resistance was designed according to the method of terrain machines reducing adhesion and resistance. The movement process of press device was analyzed. The suppression device, scraping angle to take off the soil, and soil compaction mechanism analysis were done. The mechanism analysis can provide theoretical basis for the design of the press device, and based on that the key components of press device was designed. For the study performance of press device in mechanical type reducing adhesion and resistance, the spring stiffness coefficient, speed and scraping angle were taken as experimental factors, traction resistance, soil adhesive quality were taken as test indexes. The orthogonal test L9(34) was conducted in the indoor soil bin for getting test factors affecting the performance of press device work. Test results showed that the order of the various factors affecting were as follows: the spring stiffness coefficient, scraping angle and speed;the best combination: the spring stiffness coefficient was 40N/mm, scraping angle was 30°, and speed was 7km/h. To the optimal level combination of verification experiment: traction resistance was 39.6N, and soil adhesive quality was 43.24g. Compared with the traditional repressive device, the results showed that the press device based on scrape and vibration principle can reduce the traction resistance by 17.8% and the soil adhesion can be reduced by 34.8%.

Abstract:In order to improve the efficiency of rind-pith separation for corn stalks, a kind of roller-teeth husking roller was designed. It firstly achieved elastic-plastic deformation of rind and pith in the feeding and compaction process, meanwhile, the shearing device cut corn stalks into segments to realize rind and pith separation. Based on this principle, a roller-teeth husking roller device was designed by applying the solid isotropic microstructures with penalization （SIMP）method, and a finite element simulation analysis was made on the husking roller, and the following data for the husking roller were obtained as follows: radius of husking roller was 33mm, height of toothed blade was 2mm, toothed blade thickness was 2mm and blade angle was 30°. To find out the optimal parameter combination, a quadratic regression rotation-orthogonal combination design test was made by taking rind and pith separation rate as the test index, and rotating speed of the husking roller, toothed blade clearance, cutting length of stalk segments as test factors. After test data treatment and analysis with the software Design-Expert, a mathematical model on test index and factors was set up. After parameter optimization, the optimal parameter combination for the rind and pith separation husking roller device was obtained: the rotating speed of the roller was 295r/min, roller-teeth clearance was 5mm, length of stalk segments was 22mm, and the separation rate was 85%. The test proved that the results could basically meet the working requirements, which were in line with the analysis results. Conclusions can be drawn that the roller-teeth husking roller had good adaptability. Reference for the design of the roller-teeth husking roller can be provided.

Abstract:To explore the hydraulic performance of the impact water turbine of JP75 hose reel irrigation machine, experimental investigations were conducted by replacing the load of the machine with the baking torque of an eddy-current brake. The internal flow characteristics of the turbine were also investigated numerically based on the SST k-ω turbulence model. On this basis, orthogonal numerical experiments were made to determine the main factors affecting the hydraulic performance of the turbine. The results showed that the power and head loss of the turbine were increased as a parabola with the increase of the flow rates, but the maximum efficiency of the turbine under different conditions was less than 35%. A recirculation zone was found downstream of the inlet nozzle exit, which reduced jet velocity of the nozzle, resulting in the reduction of torque produced by the turbine. The flows out of the nozzle passed the impeller mainly through a mainstream impeller passage, and the pressure on the pressure side of the blade in the mainstream passage was higher than pressure in other areas of the impeller. The flow velocity in the annular channel downstream the trailing edge of the blades was relatively high, which blocked the flow inside the impeller and resulted in the recirculation in the impeller passages. The diameter of nozzle orifice and the blade tip clearance had significant influence on the hydraulic performance of the water turbine. An improved water turbine, with a novel nozzle and appropriate blade cutting and axial impeller-casing clearance was obtained based on the numerical orthogonal tests. The best efficiency of 52.21% was achieved for the modified model optimized by numerical orthogonal experiments. Compared with the original model, the modified model showed a significant overall reduction in head loss (20%~30%), an improvement in output power (10%~15%) and an efficiency increment of 12~17 percentage points under different operating conditions.

Abstract:Agricultural spraying unmanned aerial vehicles (UAV) become a new hot spot in intelligent agricultural machinery field. It has a lot advantages over traditional spraying method like manual spraying and machine spraying. There is an urge need of UAV spraying technology. Meanwhile, since UAV onboard spraying takes a lot of time to prepare and is highly risky because for now there was a lack of customized flight controller for agriculture spraying. The development of an UAV aerial spraying simulation system was described. This system was developed for aerial spraying theory and methods test so as to shorten experiment cycle and motivate new spraying methods to be optimized. The system was designed and developed as a high precision, highly automated unmanned aerial vehicle (UAV) simulation platform to perform UAV indoor test. The system mechanical precision was maximum 2mm error for horizontal, maximum error 1mm for vertical, maximum load weight 50kg. MFC-based upper machine software was designed and it was communicated with the main control board to realize the horizontal and vertical directions movement. CAN bus was used for communication between main control board and the far end spraying unit controller. The far end spraying controller controlled spray flow control and rotor speed. This system can effectively reduce the spraying test vehicle costs, reduce the risk, and promote the UAV spraying technology development and testing. The system can be expanded to the agricultural plant protection spray test area in many places.

Abstract:The movement patterns of droplets on a UAV spray platform are quite different from those on a ground spray system because of its height from the target plants and the influence of the down-wash airflow. Few publications have mentioned how the UAV flying height influenced the spray width. Based on XV-2 UAV, by means of flow simulation and iteration calculation and experiments, the velocity characteristics of the rotor down-wash airflow and the movement patterns of droplets as influenced by the down-wash airflow were analyzed. The simulation results revealed that the velocity discrepancy from the middle to the outwards of the down-wash airflow led to an expanding tendency of airflow and thus an expansion of the spraying width. The spraying width was basically proportional to the flying height. The curling airflow around the rotor led to two peak values of droplet deposition within the spray width, which might also lead to an increase of spray drift. The experiment result showed that the effective spray width was 10m at a flying height of 6m and 12m at a flying height of 8m. The uniformities of deposition distribution were almost the same between each flying height. Considering the uniformities of deposition distribution, efficient spray deposition, spray drift caused by cross wind and injury of plants caused by down-wash airflow, the flying height of the UAV should be correctly chosen from a proper range based on its type and load. The experiment result was consistent with the simulation result. Therefore, the research result explained the influence of UAV rotor down-wash airflow on spray width and it can provide reference for the design of UAV spraying system and the choice of working parameters of UAV spraying.

Abstract:Double suction centrifugal pump has characteristics of large flow rate and high head. It is widely used in agricultural irrigation and water delivery and other projects. The volute and the impeller in double suction pump have rotor-stator interaction. The match between the two will have an impact on the hydraulic performance of double suction centrifugal pump. Therefore, it is very important to study the matching relationship between the volute and the impeller. The CFD numerical simulation was combined with the experimental data. By studying the impact on the hydraulic performance with different specific speeds, the optimal volute area ratio and its regular pattern were obtained. The findings were as follows: when the volute area ratio was increased, the maximum efficiency point was shifted to the large flow rate. The head and efficiency were decreased, and the average efficiency of the high efficiency area was reduced. When the area ratio was reduced, the head and efficiency were increased in a certain range, and the maximum efficiency point was moved to the small flow condition. However, when it was reduced to a certain extent, the head and efficiency showed a rapid decline. Finally, based on the summary of the optimal volute area ratio of the double suction pump with different specific speeds, it was found that with the increase of the specific speed, the optimal volute area ratio was increased, and the range of the high efficiency area was widened gradually. The results provided a reference for the reasonable selection of the volute area ratio in double suction centrifugal pump and improved the hydraulic performance of double suction pump.

Abstract:The impeller of a single-blade centrifugal pump has an asymmetric characteristic, and the secondary flow vortex is easy to form in the spiral volute, which will induce high pressure fluctuation and affect the safety and stability of the pump system. In order to reveal the unsteady characteristics of the secondary flow inside the spiral volute, a single-blade centrifugal pump was chosen as the research object to investigate by numerical simulation. The SST k-ω model was applied to simulate the three-dimensional unsteady viscous incompressible flow in the centrifugal pump. The predictions of the numerical model were compared with experimental results, and it showed good agreement between the simulation and experiment results. The pressure fluctuation characteristics of single-blade centrifugal pump under multiple conditions were studied. The results showed that the flow field in the pump presented obvious pressure fluctuation characteristics under different flow conditions. The pressure fluctuation intensity of the first section of the volute was the lowest, and the pressure fluctuation intensity of the second section was the highest. The dominant frequency of pressure fluctuations was the blade pass frequency. With the increase of the flow rate, the amplitude of the dominant frequency was decreased. Then the secondary flow inside the spiral volute of the single-blade centrifugal pump was further analyzed. Under the three flow rate conditions, the secondary flow vortex appeared in the volute, the shape of which showed obvious periodicity. The magnitude of cross flow velocity was decreased firstly and then increased with the increase of the flow rate. It was relatively small under the design flow condition while it was increased significantly under off-design condition. The research can provide theoretical basis for the safe and stable operation of single-blade centrifugal pumps.

Abstract:In order to obtain the cavitation performance and force on runner of pump-turbine in pump mode, the model pump-turbine in a pumped storage power station was selected as the study object. Based on SST k-ω turbulence model and Zwart cavitation model, the numerical simulation was carried out for fully-three-dimensional unsteady flow field with different cavitation coefficients and compared with the experiment results. Turbulent kinetic energy distribution on the middle stream surface of runner and guide vanes, the vapor volume and loading distribution on blades was discussed, and then force on runner was quantitatively analyzed. Results showed that the numerical analysis results can be used to capture development of the cavitation;with the decrease of the total pressure in draft inlet, the turbulent kinetic energy was increased gradually in outlet of the runner and decreased gradually in outlet of guide vanes, vapors generated at suction side of blade near the leading edge at first and then extended to the exit of runner and pressure side of blade;due to rotorstator interaction about runner and guide vanes and asymmetry of the volute’s shape, periodicity and symmetry of variation of radial force on the runner was gradually destroyed. The research findings can reveal the cause of operation became worse for pump-turbine in pump mode.

Abstract:Fixed and mobile global navigation satellite system (GNSS) reference stations are the main differential positioning resources for automated steering system in China at current stage. However, with the rapid increase in GNSS reference stations usage, there is an increasing trend of serious radio frequency interference, which mainly due to deficiency of technical and management coordination. To solve this problem, a cloud based architecture that achieved regional GNSS reference stations management and information sharing for agricultural applications was proposed. Shihezi, a district of Xinjiang, was selected as the study area. The accurate information (i.e., name, position, and frequency) of 84 fixed reference stations from three enterprises was collected, based on which the difference of distance (ΔD) and the difference of frequency (ΔF) between each two reference stations were calculated. By using ΔD and ΔF, redundancy and frequency interference were analyzed, coordinate adjustment of two stations were conducted, and the prototype system and an APP were developed for reference station management and agricultural applications. The results showed that the 84 reference stations occupied 26.7MHz frequency band with 47 frequencies, and 30 of which were independent frequency. In addition, there were 18 couples of stations using the same frequencies and 29 pairs of stations using near frequencies（ΔF≤25kHz） within 40km in northeast of Shihezi. The average redundancy was 263.2%, and the redundancy of central area was even worse. To benefit from the redundancy information, it was utilized to adjust the coordinate of the GNSS reference station in order to improve the reliability of differential signal access. Three stations were tested and the precision to millimeter level and centimeter level for longitude and latitude respectively, which meant the coordinate adjustment can improve the accuracy of GNSS reference stations. The prototype system and APP achieved the functions such as stations recording, interference detection, station construction assistance, and frequency recommendation, and it can improve the management efficiency of GNSS reference stations and reduce radio frequency interference.

Abstract:Leaf area index is one of the important parameters to describe the canopy structure of corn, which determines the biophysical processes of corn canopy photosynthesis, respiration, transpiration and carbon cycle. Therefore, retrieval of leaf area index is of great significance to corn growth monitoring. The Sentinel-2 remote sensing image and LAI-2000 ground synchronous data were used to retrieve the leaf area index of corn canopy. Normalized difference spectral index (NDSI) and ratio spectral index (RSI) were extracted to build the univariate and multivariate empirical models. The best LAI retrieving models were identified based on the best combinations of coefficient of determination (R2) and root mean square error (RMSE). Finally, spatial distributions of LAI in the study area were mapped through the optimal retrieve model. Results showed that all spectral indices tested were significantly correlated with LAI of corn, and the correlation between spectral indices built with red-edge bands and LAI was higher than that built without red-edge bands. Validation analysis result indicated that although the accuracy of the multivariate empirical model was high, its ability to predict LAI was poor. Linear regression model of NDSI（783,705） most accurately explained retrieval of LAI of corn, with R2 of 0.5342 and RMSE of 0.2885. Therefore, linear regression model of NDSI（783,705） was recommended as the most legible model for estimating LAI of corn. The red-edge bands confirmed from Sentinel-2 remote sensing image improved the accuracy of retrieving the LAI of corn. Moreover, the results also provided a powerful evidence to develop the Sentinel-2 remote sensing image and red-edge bands application in retrieving the LAI of corn.

Abstract:Farmland shelterbelt is a major component of land reclamation, farmland protection and the engineering construction of ecological environmental protection. And the information acquisition of farmland shelterbelt is an important approach to supervising engineering, such as land reclamation and so on. The automatic recognition method of farmland shelterbelts was explored by taking full advantages of the spectral and morphological features in high spatial resolution remote sensing data based on GeoEye-1 satellite remote sensing image (0.5m-resolution). Firstly, the classification decision tree was established by making use of the normalized difference vegetation index (NDVI) and two-dimensional entropy of GeoEye-1 satellite remote sensing image. Secondly，the preliminary extraction results of farmland shelterbelts were found out by combining with the auxiliary data. Thirdly, the preliminary extraction results were processed by morphology operations, including expansion, hole filling, de-noising and thinning, to get the continuous and refined extraction results. The partial region of the oasis in the southern margin of Badain Jaran Desert in Linze County, Gansu Province was taken as a typical study area for instance validation, which is located in the central Hexi Corridor. The experimental result indicated that by using the method the automatic recognition precision of farmland shelterbelts were all above 92% and the average accuracy reached 92.97%, the spatial coincidences were all above 86% and the average anastomosis reached 93.13%. So it can satisfy the actual demand in supervising engineering, such as land reclamation and so on. The method can provide scientific support for the farmland shelterbelts construction and the related engineering supervision.

Abstract:Air temperature within canopy reflects the growing condition of plants objectively. Simulation of air temperature within canopy can assist in better understanding of microclimate dynamic change characteristics, and can also provide a scientific basis for monitoring late frost injury of winter wheat. A field experiment was conducted in Shangqiu City, Henan Province to observe the winter wheat growth and ambient environmental factors. Based on the localization，coupled WOFOST and SHAW models were applied to simulate dynamic characteristics of air temperature hourly within winter wheat canopy from 0cm to 80cm at after-jointing stage in 2016, and the simulation results were compared with measured data. The results suggested that for coupled WOFOST and SHAW models, model efficiency of the simulated and measured values at different heights within winter wheat canopy was greater than 0.90, and over 75% of absolute errors of simulated values were in the range of -1.5~2.5℃，showing a high accuracy in simulating air temperature within winter wheat canopy as a whole. For daily lowest values of air temperature within winter wheat canopy, model efficiency of coupled WOFOST and SHAW models was about 0.86, and the simulation values of daily lowest values of air temperature within winter wheat canopy were 0.53℃ greater than measured values，showing an excellent conformity between simulated and measured values. And the simulation values could precisely reflect daily lowest values of air temperature below 0℃ within winter wheat canopy where the late frost injury occurred easily. Therefore, coupled WOFOST and SHAW models can simulate air temperature within winter wheat canopy well, increase applicability of SHAW model, and provide a reference for monitoring late frost injury.

Abstract:With the increase of non-point source pollution emissions, the degree of eutrophication in water source is becoming seriously increase. Turbidity is an important parameter of water quality assessment, as an indicator of eutrophication. A discrete binary particle swarm optimization-partial least squares (PLS) model was proposed to reduce modeling uncertainty of turbidity retrieval using PLS and improve retrieval accuracy. A discrete binary particle swarm optimization was used to select original spectral reflectance and normalized spectral reflectance of concurrent HJ-1A HSI hyperspectral data with the turbidity obtained from October, 2015 in Weishan Lake as the input of partial least squares model. OSR-PLS and NSR-PLS model retrieving turbidity were developed by using original spectral reflectance and normalized spectral reflectance in full spectrum (HJ-1A HSI B26-B105 with 518nm to 870nm (central wavelength)). Meanwhile, the OSR-DBPSO-PLS and NSR-DBPSO-PLS models were developed to retrieve turbidity by using the selected original spectral reflectance and normalized spectral reflectance. The influence of spectral normalized and the characteristic band optimized on PLS model retrieval accuracy were analyzed based on the four models’ elevation. Finally, the highest accuracy model was used to retrieve the turbidity distribution in Weishan Lake. The results indicated that the accuracy of NSR-PLS (R2=0.91) model was better than that of OSR-PLS model (R2=0.50). The normalization of reflectance can improve PLS accuracy of turbidity retrieval. DBPSO can identify the optimal original and normalize spectral reflectance. The number of bands required for turbidity PLS modelling was reduced from 80 to 44 (OSR) and 36 (NSR), respectively. The OSR-DBPSO-PLS (R2=0.96) and NSR-DBPSO-PLS (R2=0.97) modelling based on 44 OSR and 36 NSR, respectively, had high accuracies, which were significantly higher than the OSR-PLS and NSR-PLS modelling by full spectrum. The NSR-DBPSO-PLS model with minimal comprehensive error was selected to retrieve turbidity in Weishan Lake, which was suitable for inland water turbidity retrieval based on HJ-1A HSI data.

Abstract:The aims were to determine the efficiency and its temporal-spatial evolvement characteristics by using data envelopment analysis (DEA), Malmquist index and exploratory spatial data analysis (ESDA) in 20 main producing provinces of maize in China during an 11 years period (2005—2015). The results showed that the average value of scale efficiency, comprehensive and pure technical efficiency of maize production in the study areas were unproductive. The high comprehensive technical efficiency was positively correlated with production methods. With an annual decrement of 6.7% in total factor productivity, mainly due to the lack of effective application of the production technology. The difference of the comprehensive technical efficiency between the provinces was mainly affected by the mode of agricultural production (especially technology, etc.), the scale of operation and the proportion of agricultural production. The provinces with high efficiency had both higher technical efficiency and scale efficiency, while the difference between the technical efficiency and the scale efficiency was relatively large for the provinces with lower efficiency. Lack of regional application of advanced production technology led to the reduction of total factor productivity. Various input elements of maize production were unreasonable, which can all be saved by using advanced and applicable production mode. The comprehensive technical efficiency in study areas showed obvious spatial clustering, while the spatial clustering of similar efficiency was not strengthened during the past 11 years, which was weakened in some years, the spatial differences were also expanded in each area. There were significant positive correlations in the northern area and Huang-Huai-Hai area of China. Improving the effective use of regional applicable technology and scale of operation were keys to improve the production efficiency of maize. Simultaneously, optimizing the spatial layout in main producing provinces of maize to achieve the “H-H” types was essential to improve the efficiency and competitiveness of maize production in China.

Abstract:It is a pivotally strategic measure for China to carry out the rural land consolidation and construct a large-scale well-facilitied farmland which gives stable production despite drought or excessive rain. Because of the different topography, landform, specific factors that restrict agricultural production, the key to solve the well-facilitied farmland construction is also different. Therefore, the most urgent and the prominent obstacle factors that affect the improvement of soil fertility in the well-facilitied farmland construction project must be grasped, so as to eliminate the barrier factors and solve the main problems in the process of land consolidation. The research on the diagnosis of farmland construction obstacle factors was carried out based on Xinzheng City. The research was based on the theory of ecological niche. In the process of diagnosis, the niche suitability evaluation model and the thought of index deviation degree were combined to construct disorder factor diagnosis model based on ecological niche. The index deviation from the optimal niche and the niche deviation of each evaluation factor were calculated by using the model, and the barrier degree of each index was got. Then, the obstacle degree of each evaluation unit was obtained according to the Shefold restriction law. Finally, the factor of the barrier factor value Oi more than 0.4 of each evaluation unit in the region was screened out. The frequency of these factors was calculated and sorted according to the order from large to small, so as to dig out the main obstacle factors affecting the construction of well-facilitied farmland in Xinzheng City. The model not only overcame the limitations of the subjective weighting in the current diagnosis model of obstacle factors, but also replaced the 100% values in the index deviation model with the optimal niche value, providing theoretical and scientific basis to determine the 100% degree model values of deviation. The model made up for the deficiency of the barrier factor diagnostic model, and made the barrier factor diagnosis model more scientific and reasonable. It provided a new approach for the diagnosis of obstacle factors, and expanded the application of niche theory at the same time. The results showed that the overall obstacle degree was not so high in Xinzheng City. The total farmland area below obstacle degree score of 0.5 was 22741.14hm2, which accounted for 41.98% of the total farmland area in the study area;the total farmland area whose obstacle degree score was in interval of ［0.51,0.65] was 22493.79hm2, which accounted for 41.53% of the total farmland area in the study area;the total farmland area whose obstacle degree score was in interval of ［0.66,0.8] was 3873.96hm2, and the total farmland area above obstacle degree score of 0.8 was 5059.05hm2, separately accounted for 7.15% and 9.34% of the total farmland area in the study area. The overall natural endowment of cultivated land in Xinzheng City was pretty good, so the main limiting factors to well-facilitied farmland construction in Xinzheng City were guaranteed rate of irrigation and drainage conditions as well as part of low soil organic matter and high soil pollution index. By using this model, the spatial distribution information of main barrier factors of well-facilitied farmland construction in Xinzheng City was obtained, which was consistent with the results of field investigation and analysis, so that the validity of the model was verified. The model reliably provided a basis for the design of well-facilitied farmland construction plan.

Abstract:The stability and suitability of reclaiming dryland soil into paddy soil in Suixi County were analyzed, and a selecting construction method was provided based on the coupling coordination degree model and hotspot analytical skill. The results showed that Suixi County had more potential to reclaim dryland soil into paddy soil. The high and medium suitable area were 81.08% of the total cultivated area, mostly were distributed in eastern villages and towns. The stability and suitability had distinct spatial distribution. The high stable areas were located in Beipo Town and Guangqian Company and some other towns. Yanggan Town, Beipo Town, Jiepao Town and Guangqian Company were easier to be reclaimed, which accounted for 41.04% of the total remodel area. Those places had abundant natural resources and well-constructed infrastructures, and enjoyed a perfect distance of the public traffic highways. Finally, most hotspots that were suitable and stable for reclaiming were located in Yanggan Town, Beipo Town, Jiepao Town and Guangqian Company, which had more priority in reclaiming process. The total constructional area for land reclaiming was 462.75hm2 in Suixi County during the 13th Five-year Plan. This research provided methodological reference for further scientific selection and reclaiming dryland soil into paddy soil distribution.

Abstract:To solve the shortcomings of non-intelligent, non-integrated and low efficiency of traditional method for measuring diameter at breast height (DBH), tree height and forest stand spatial structure parameters, a laser photogrammetric instrument for measuring forest based on the principle of photogrammetry, image processing technology, sensor technology and forest measurement was designed. The instrument was composed of CCD sensor, laser, LED flashlight, self-developed PDA and shell. There were three modular procedures which were compiled in the Java language and developed in Android Studio 2.2 systems development environment. The three modules were DBH measurement, tree height measurement and forest stand spatial structure parameters measurement. These three functions were achieved by obtaining parameters such as dip angle, azimuth and image information. The experiment of measuring DBH, tree height with 21 trees as samples and measuring forest stand spatial structure parameters with 15 reference trees in a plot as samples. Compared with the traditional measurement method, the mean absolute value of the relative error of DBH measurement was 2.55%, the tree height was 2.82%, the uniform angle index was 2.50%, the dominance was 2.86% and the measurement of the mingling was consistent with the traditional measurement method. The measurement accuracy of the instrument can meet the requirements of forestry survey. The method of using the laser photogrammetric instrument for measuring forest to measure the forest stand spatial structure parameters can be done which only required one person. Compared with the traditional measurement method, this method saved a half of labor and 31% of the working time. The instrument had a good prospect in the field of forestry basic investigation and forest stand spatial structure.

Abstract:In order to investigate the response of photosynthetic characteristics of spring wheat under water deficit and plastic mulching conditions in Northwest China, field experiment was conducted with four treatments, including full irrigation without mulching (W1M0), full irrigation with mulching (W1M1), deficit irrigation without mulching (W2M0) and deficit irrigation with mulching (W2M1). The light response curves were monitored with five different light response curve models which were compared. The influences of field mulching and water deficit on photosynthesis of spring wheat were discussed and the applicability of the light response models were evaluated. The results showed that water deficit can reduce the main characteristic parameters, including maximum net photosynthesis rate (Pmax), apparent quantum efficiency (AQY), dark respiration rate (Rd), while light compensation point (LCP) was increased. However, treatments of mulching can slow down the decrease of spring wheat photosynthetic rate effectively. There were obvious differences for treatment W2M0 in the simulation results of the five models, where only Ye Zi-Piao model could well fit the actual values, and especially for the high photosynthetic active radiation section, with the coefficient of determination (R2) greater than 0.9, while the fitting effects of the rectangular hyperbolae model, the non-rectangular hyperbolae model, the exponential model and the kinetics model were poor, which were only about 0.7. Their determination coefficients were in the descending order as Ye Zi-Piao model, non-rectangular hyperbolae model, exponential model, rectangular hyperbolae model and kinetics model.

Abstract:In order to investigate the effect of rhizosphere aeration on NH+4-N and NO-3-N absorption and metabolism of red globe grape seedlings, the experiment was done by taking 2-year old red globe grape seedling as test material, through subsurface drip irrigation（SDI） with tanks technique and 15N tracer technique to study effect of the rhizosphere aeration treatment on plant growth and NH+4-N and NO-3-N absorption, distribution and utilization. The results showed that rhizosphere aeration under SDI with tanks could promote the growth of new shoots, increase the stem diameter, and especially significantly increase the dry matter accumulation of new shoots and fine roots. In the same irrigation period, rhizosphere aeration under SDI with tanks increased the SPAD value and net photosynthetic rate of the leaves, but it had negative effects on the instantaneous water use efficiency of the plant leaves. The nitrogen isotope tracer results showed that grape new organs on the NO-3-N Ritchie ability, absorption and utilization efficiency were significantly higher than that of NH+4-N under aeration treatment and without aeration treatment, and the results showed that rhizosphere aeration under SDI with tanks did not affect the nitrate preference of grape plants. The results also showed that gas injection treatment can significantly promote the absorption of nitrate uptake and utilization of new organs, inhibition of ammonium nitrogen, which suggested that nitrate nitrogen should be selected as nitrogen source under the condition of rhizosphere aeration under SDI with tanks.

Abstract:To explore the effects of different irrigation quotas and irrigation frequencies on winter wheat yield and grain quality under center pivot irrigation system, a field experiment on fertigation of winter wheat was carried out in 2014—2016 at Shunyi District, Beijing. Three irrigation treatments (W1, W2 and W3) were investigated with irrigation quotas of 135mm, 112.5mm and 90mm in 2014—2015, and 154.5mm, 132mm and 109.5mm in 2015—2016, respectively. Irrigations were applied at recovering-jointing stage, jointing-heading stage and heading-grain filling stage respectively, as the soil water content reached 70%, 75% and 75% of the field capacity, respectively. Each irrigation was sprayed at one time (C1) or at two times (C2) with equal irrigation amount at 9 d interval. The results showed that both the total water consumption and the average daily consumption of winter wheat from jointing to heading stage were the largest, and the highest yield was achieved under W1 treatment. The effects of the irrigation quota and irrigation frequency on water use efficiency were not significant in 2015—2016. The water use efficiency was decreased with the increase of irrigation quota, and the largest water use efficiency was 2.28kg/m3 at W3 treatment. Under the treatments of W1 and W2, the irrigation at two times can improve the spike number, yield and bulk density of winter wheat. The maximum yield was 9286.4kg/hm2 under the treatment of W1C2. The irrigation quota had more effect on wheat yield than irrigation frequency. Comprehensively, an effective method of irrigation was suggested for winter wheat in Beijing at recovering-jointing, jointing-heading and heading-grain filling stages with 45mm, 55.5mm and 54mm, respectively. Each irrigation could be applied equally at two times under center pivot irrigation system.

Abstract:Estimating heavy metal bioavailability, mobility and transfer is important to environmental and food safety. A greenhouse study was conducted by using Brassica chinensis to investigate the movement of chromium (Cr) from soil to plants and predict the main factors influencing Cr bioavailability. The result showed that soil organic carbon (OC) content, pH value and total Cr content had a significant impact on Cr uptake. The plant Cr contents were positively correlated to total soil Cr contents and negatively correlated to soil OC and pH value. Stepwise multiple linear regression (SMLR) (pH value, OC and total soil Cr contents) relationships (R2 was 0.927) could more accurately estimate Cr bioavailability relative to single-factor (total soil Cr contents) equations (R2 was 0.861). The maximum bioconcentration factor (BCF) was measured in acidic soils. The most accurate Freundlich equation for estimating Cr bioavailability was developed by using data from combined CK, Cr1 and Cr2 treatments (R2was 0.927, RMSE was 0.12, n was 45) compared with the Freundlich equation developed by using the date CK treatment alone (R2was 0.572, RMSE was 0.25, n was 15) and using data from only combined Cr1 and Cr2 treatments (R2 was 0.745, RMSE was 0.17, n was 30). The results can be used to predict Cr transfer from soil to plant systems.

Abstract:There are randomness and fuzziness to a large extent in soil nutrient synthetic evaluation. In order to effectively solve the uncertain transformation problem between the qualitative concepts and evaluation indexes, which are described by membership function, based on the cloud theory and fuzzy mathematics theory, a fuzzy synthetic evaluation method was presented based on the cloud model. Taking Da’an City in Jilin Province as the research object, totally 7 soil nutrient elements contents were selected such as organic matter in the cultivated layer as evaluation, and the weight of each index was determined by using entropy method. The cloud model was applied to the comprehensive evaluation of soil nutrients, and the soil nutrient fuzzy comprehensive index of each evaluation unit was obtained (cloud fuzzy comprehensive index, CFCI). In addition, COK was used to get the interpolation of CFCI, and a distribution map of soil nutrients CFCI grade was formed. The results showed that the evaluation results from the data characteristics of the study area, CFCI was in the range of 2.43 ~ 4.89, the average value was 3.78, the standard deviation was 0.45, coefficient of variation was 11.85%, which was in moderate degree of variation;from the perspective of spatial distribution pattern of the evaluation results, the comprehensive level of soil nutrients in Da’an City was decreased gradually from north to south, and the higher concentration of cultivated land was, the higher the level of soil nutrient comprehensive was.

Abstract:Information about the concentrations of heavy metals in pig manure from large-scale pig farms was collected from 21 provinces and cities in China, and information about the concentrations of heavy metals in pig feeds was collected from 11 provinces and cities. The data were analyzed systematically to evaluate the total amount of pig manure and heavy metals produced in each province. The period over which the pig manure could safely be applied to agricultural land was assessed by calculating the total amount of heavy metals found in the manure produced and the total land available for application in each province and city. The results indicated that in the 21 provinces and cities, 20 of them had pig manure samples that were over the recommended concentration limit for Cu, 18 of them were over the limit for Zn, six of them were over the limit for As, four of them were over the limit for Cd and one of them was over the limit for Cr. Moreover, in 10 provinces 100% of the pig feed samples were over the national standard for Cu (13.2~49.0 times of the standard) and in one province 75% were over the standard. On average, for Zn concentrations the pig feeds were 1.3~9.5 times of the national standard. There were significant positive correlations for Cu and Zn between pig manures and feeds (p<0.01). The main limitations to the land application of the pig manure were due to the amounts of Cu, Zn and Cd. For example, in Jilin, Liaoning and Shandong Provinces, the concentrations of Cd in soils would exceed the environmental quality standards for soils after 16, 23 and 91 years, respectively, if the manure was applied to land in these provinces at the current rate. Additionally, the concentrations of Cu and Zn in soils in Beijing would exceed the standards in 65 and 51 years, respectively, while in Tianjin the soil standards for Cu and Zn would be exceeded in 53 and 91 years, respectively. This analysis suggested that it was important to control the rates of pig manure application in agriculture and reduce the amounts of Cu and Zn in pig feeds.

Abstract:In the intelligent greenhouse environment control system using wireless sensor networks, the crops growing is usually affected by various factors from the environment. The greenhouse control system makes inappropriate decisions based on the received measurements of wireless sensor networks, which will lead to go against the growth of crops. In view of this, a novel decisionmaking framework based on Dempster-Shafer (D-S) evidence theory was established to meet practical requirements of the greenhouse environment control system. Moreover, two approaches of the data preprocessing and the decision fusion were proposed, respectively. Firstly, the measuring outliers data were detected by using the box-plot, and then an effective approach was proposed to correct them adaptively, which overcame the disadvantage of directly removing the outlier data in existing approaches. The corrected measuring data were also clustered by using the weighted average distance. Finally, a novel basic probability assignment approach was proposed to make correct decisions for the control of greenhouse environment based on the D-S evidence theory. Experimental results demonstrated that the outliers detection rate of the box-plot was more accurate than that of the Dixon criterion (nearly 19.2%). Compared with existing approaches, the fusion performance of the uncertainty was reduced by 1~2 order-of-magnitude in the proposed basic probability assignment approach, which not only increased precision of environmental indicators for the greenhouse control, but also accelerated the convergence process and reduced the risk of decision-makings effectively.

Abstract:High concentrations of particulate matter (PM) emitted from animal feeding operations (AFOs) may adversely affect the health of the farmers and welfare of animals. Large quantities of PM released to the atmosphere can be transported away from sources causing environmental problem and health issues of people living in the vicinity of farms as well. PM characterization was mainly talked about inside and outside of the mechanical ventilation of caged laying hen house which used the fan to release PM outside of the house, and the propagation law of PM was studied as well. Results showed that the concentration of fine PM, which was the most harmful to the human body, was mainly derived from the inside and outside of the house, and the concentration of the PM outside was up to 55.2%, which mainly came from inside;the smaller the PM size was, the farther the distance was away from the air, which was more likely to affect the health of the vicinity of the farms;by analyzing the concentration inside and outside of daily variation of PM, it was found that the inner staff activities and feeder disturbance inner deposition of PM led to the laying hen activity enhanced which would increase the concentration inside and outside. At the same time, indoor and outdoor PM concentrations were increased with the age of laying hen and air humidity;meanwhile, to control the indoor PM concentrations and using the appropriate measures to remove the indoor PM would help to ensure the health of staffs and welfare of animals, and reduce the hazards of PM to the surrounding environment.

Abstract:In order to extend the plucking period of spring tea and improve its yield, the shading cultivation experiment was carried out. Three treatments with different shading rates and shading heights were applied as 60% shading rate with shading height of 2.0m（T1）, 40% shading rate with shading height of 2.0m（T2）, 40% shading rate with shading height of 2.5m（T3）and none-shading（CK）. The experiment period was divided into early, middle and late stages from final harvesting period. The differences of temperature, relative humidity, growth status and tea quality among all treatments were analyzed. Compared with CK, the results showed that after shading, maximum daily air temperature around canopy was decreased significantly with the maximum temperature drop of 3.85℃ and average minimum relative humidity around canopy was increased with the maximum increase of 9.01% from 08:00 to 17:00;the new twig length and the stem thickness of T1 were increased by 22.3% and 13.5%, respectively;as shading rate was increased, relative chlorophyll content（SPAD）and water content of leaves and buds were increased;the average photosynthetic rate of leaves of T1 was increased, while those of T2 and T3 were decreased;as for T3, water extract, polyphenols and the ratio of polyphenols to amino acid were increased, but amino acid was decreased, leading to the tea tasted thicker and bitter;as for T1, its caffeine was increased, while water extract and the ratio of polyphenols to amino acid were decreased significantly during the early stage. Therefore, shading cultivation with shading rate of 60% was of significance to maintain the quality of spring tea, extend the plucking period and increase yield during final harvesting period.

Abstract:The depleting stocks of fossil fuels have forced researchers to investigate renewable fuels and chemicals as an alternative to petrochemical products. Recently, more and more attentions have been paid to lignin for product bio-fuels. However, lignin as a by-product of black liquor discharged from industrial pulping process has not been used reasonably. It is the only renewable resource that can direct provide aromatic ring in nature. Lignin is an amorphous and highly branched polymer through C—O or C—C bonds, and the polymer molecular structure of lignin is very difficult to be degraded into phenyl propane monomers. Therefore, the selective depolymerization of lignin structure into smaller molecular units is the major challenge for converting it to value-added chemicals. In order to study the catalytic depolymerization mechanism of ethanol organosolv lignin (EOL) by raney nickel, the pyrolysis experiment of pure EOL and raney nickel loading EOL were investigated by a Fourier transform infrared spectrometry (TG-FTIR). Then the effect of raney nickel on the thermogravimetric characteristics and the releasing ways of the volatiles products were analyzed. The results suggested that the raney nickel catalysis improved the breakage of ether bond between lignin structure unite, and then led to the formation of phenols, hydrocarbons and CO2 products increased and the release of CH4 and ketones products decreased. Meanwhile, the DTG peak temperature of raney nickel loading EOL was 50℃ lower than that of pure EOL, while the formation temperature of CH4 was increased.

Abstract:The pyrolysis characteristics of fermentation residue of corn stover was analyzed. The pyrolysis kinetics were studied with FWO and Starink methods. The most probable mechanism function of pyrolysis also was evaluated by Malek method. The effect of anaerobic digestion on corn stover was deduced by comparing with the untreated corn stover. The results of proximate and ultimate analysis showed that the volatile content of fermentation residue was decreased by 19.48% compared with the untreated corn stover and the fixed carbon content was increased by 27.87%. The oxygen content was decreased by 24.25%, which was an advantage for pyrolysis. The analysis of lignocellulose illustrated that cellulose and hemicellulose were decreased by 39.94% and 30.96%, respectively, while the lignin was increased by 109.14%, which contributed to the maximum weight loss rate of fermentation residue decreasing and the carbon yield was much higher after pyrolysis. The results of pyrolysis kinetics showed the activation energy of fermentation residue was 91~130kJ/mol，which was lower than that of corn stover. The mechanism function curve of two samples had similar trends, which can be divided into two parts. When the conversion ratio (α) was less than 0.6, they can be illustrated by order of reaction (n=2) mechanism model. When the conversion ratio (α) was more than 0.6, the pyrolysis of corn stover was in accord with the cylindrical symmetric three-dimensional diffusion mechanism (D4), while fermentation residue was more inclined to the spherical symmetric three-dimensional diffusion mechanism (D3). The research result can provide a theoretical basis for optimization of process conditions and industrial application of fermentation residue turning to bio-fuel.

Abstract:Waterless and low temperature keeping alive transportation is considered as a kind of promising technology to improve aquatic animals’ survival and save the transport costs, and monitoring biological signal is useful to improve the transparency and traceability of transportation process. A monitoring method of glucose was presented, which consisted of three components: a signal conditioning circuit, a software digital filter and a prediction method. The signal conditioning circuit was responsible to sense glucose signal by the implantable glucose sensor and signal pretreatment by a hardware filters;the software digital filter can filter and smooth the amplified signal to provide reliable data for the dynamic character analysis. The time series method served to predict change of glucose. Sturgeons were selected as experimental objectives to validate the reliability of the method. The experiment result showed that the implanted glucose sensor can sense data accurately with sensitivity of 27.047mV/nA, the zero drift of 722.83mV and signal output fitting of 0.9608 after signal conditioning circuit;the average absolute error between the predicted value by autoregressive integrated moving average model（ARIMR）and the real sensed value was -0.014mmol/L, and the average relative error was -0.117%, which indicated that the ARIMR model had advantages in prediction accuracy and smoothness compared with other prediction models;the proposed monitoring method can be adopted as a reference value to monitor the change of glucose and obtain the change of biological nutrients during waterless keeping alive transportation of the aquatic product.

Abstract:High performance liquid chromatography-coulometric electrochemical array detection (HPLC-ECD) could be used to detect with electrochemical active substances. Meanwhile, these substances are the sensory substances of Chinese spirits, particularly in sensory evaluation. A method using HPLC-ECD on Chinese spirits was established for the first time. Under the optimal chromatographic conditions, when using 8 channels, 102 characteristic peaks in Chinese spirits could be identified. All peaks were well separated with high stability and precision. The method was direct injection without pretreatment, and it did not need to qualitatively and quantitatively analyze the detected substances, which meant this method was simple, fast, low cost and high efficiency. Using this method, the Chinese spirits produced by traditional fermentation and the Chinese spirits produced by alcohol blending could be distinguished. A variety of active substances in these two kinds of Chinese spirits could be detected, the fingerprint information was rich, and there were obvious differences between the two kinds of Chinese spirits. Cluster analysis was also used for the detection of data processing, and it could achieve an accurate distinction between these two kinds of Chinese spirits. Furthermore, the method was used to analyze the liquor with different blending ratios, and the results were accurate. The liquor was divided into four groups accurately: the proportion was divided into 10%, 15%, 75% and 100%. All these data showed that this method was suitable for classification and determination of Chinese spirits.

Abstract:The drift is the inherent behavior of gas sensor, so it is more generality to reveal drift phenomena with no-load data. In order to remove the drift effectively, under the no-load condition, a drift removal method based on wavelet packet decomposition was proposed. Firstly, wavelet packet decomposition was employed to decompose the no-load data of the E-nose, and the approximation coefficient set of wavelet packet decomposition could be obtained. After the discrete analysis of the approximation coefficient set was carried out, a threshold function based on no-load data of the E-nose was constructed. And then the drift threshold function based on the sample data (loaded data) was obtained by extending the threshold function based on no-load data;furthermore, a drift elimination method for sample data was given. To test the effectiveness and practicability of the above method, it was applied to identify four kinds of white spirit samples by using the E-nose. The E-nose data of the four kinds of samples were divided into training set and test set according to the test time sequence, the identification results of linear Fisher discriminant analysis (FDA) indicated that the identification correction rates of training set and test set were all improved after their data were processed by the above drift removal method, and the minimum improvement was 23.65%, which showed that the method can effectively enhance the detection ability of the E-nose. At the same time, in order to further test the performance of the drift removal method, the nonlinear BP neural network was used to identify the four kinds of samples, and its identification results displayed that after treatment with the method, the identification correction rate of the training set was from 65.5% up to 100%, and the identification correction rate of the test set was also up to 97.5%. This not only showed that the identification of the four kinds of white spirit samples was a complicated nonlinear classification problem, but also showed that the proposed drift removal method was very effective. In addition, the drift removal method was proposed according to the no load data of the E-nose, thus it was considered to be general.

Abstract:Rice cracking occurring in the hot air drying of rice kernels reduced its quality and economic values. The reason for the rice cracking is due to the local drying stress of the kernel exceeds its resistance. The drying stress includes the stresses induced by temperature and water gradient, so the temperature and water gradient is basis for predicting drying stress. The purpose was to predict the heat and mass transfer process inside the rice kernel. The image processing technology was applied to construct a three-dimensional body-fitted grid for the rice kernel. The governing equations and relative boundary conditions were developed for the heat and mass transfer processes respectively. New measuring technology (TPS) was used to measure the properties of rice kernel such as the heat conduction and mass diffusion coefficient. Finally, the Comsol Multiphysics software was applied to solve the mathematical model. The simulation results were compared with the experimental data and the difference was less than 8%, indicating high model accuracy. The temperature and water distribution gradients in the rice kernel along the radial direction (short axis) were larger than those along the axial direction (long axis), and the duration time of water gradient existence was longer than temperature gradient existence. The moisture gradient in the radial direction from the outer surface to the one-third of center was larger than that in other parts of the radial direction, which was consistent with the cracking phenomena observed in experiments—the crack extended from the surface inward. The image processing technology was applied to construct three-dimensional body-fitted grid for the rice kernel. New measuring technology (TPS) was used to measure the properties of rice kernel.

Abstract:Aiming at the problems of labor intensity, low efficiency and poor working environment, a system of poultry slaughtering robot based on machine vision was designed. The system consisted of four parts, which included a rectangular coordinate manipulator body, poultry carcass suspension conveyor, PLC control system and machine vision system. Collecting poultry carcass and poultry muzzle images online through the visual system, the carcass image was pretreated by median filter and grayscale enhancement, and then the image was binarized by using the total fixed threshold, after setting the area threshold and obtaining the binary image which cut off the poultry wings and legs through the closed operation and hole filling. Finally, the binary image contour was calculated, the center of mass coordinates was got. In order to obtain the coordinates of center of muzzle, the poultry muzzle was positioned by the maximum internal circle method. The center of the maximum internal circle was the center of muzzle. Combining the coordinates of the center of mass with the coordinates of the center of muzzle, and then converting the coordinates information to digital information, the data of digital information would be transmitted to the PLC controller, to guide the manipulator to complete the work of the evisceration. The results of the experiment showed that the accuracy of the coordinates of poultry profile contour centroid and muzzle center was ±1.6 pixel and ±1.52 pixel. The eviscerating manipulator can accurately grasp the internal organs, the residual viscus in the body was 7.63%, and the breaking rate was 23%.

Abstract:A kind of fresh food packaging machine based on the negative pressure type was designed in view of high labor intensity and low production efficiency due to artificially packaging. The packaging machine consisted of transverse sealing device, cutting mechanism, film feeding mechanism, vertical sealing device, and so on, which was suitable for many kinds of fresh food packaging. And the structure and working parameters of the device for negative pressure type fresh food packaging machine was studied. According to the FLUENT analysis of the inner flow field of rear air suction box, the box adopted cross section of rectangular box type. And the cross sectional parameters were 25mm and 64mm. The belt conveyor was adjusted by the eccentric roller to ensure that there was sufficient pressure between the upper belt and the lower belt. Meanwhile, by using the virtual prototype of ADAMS, the influence of main parameters on motion of the mechanism was obtained. The prototype test showed that the packaging speed was 49.4pack/min, the packaging rate was 99.4%, and the swell rate was 5%, which indicated that the fresh food packaging machine could satisfy operation demand of the enterprises engaged in processing fresh food. The fresh food packaging machine with negative pressure type met the design requirement and anticipated goal.

Abstract:In order to optimize the structural parameters of automatic suction cup feeding device in egg processing line, as well as to fix the sync location of the key parts in prototype installation, a structural analysis and movement simulation was made for the core part of this device，i.e., combined suction cup swing arm mechanism. Results indicated as follows: the DOF (degree of freedom) of suction cup swing arm combination which were made up of crank, gears and timing belts in series was 1. The crank was in full rotation, rocker was reciprocating and swinging at 60°, swing arm was reciprocating and swinging at 180°;the synchronization had the angular compensation in order that suction cup parts would always be in the horizontal state when the swing arm was swinging at 180° so as to guarantee horizontal handling and transport of eggs. The curve change of swing arm end displacement, velocity as well as acceleration indicated that when the rocker swung to the accessories where the extreme position angles were 146° and 206°, swing arm had a vertical up-and-down motion whose horizontal speed was 0, respectively corresponding to crank 84°~108° and 252°~312°, in order to ensure vertical movement of suction cup in process of sucking and putting down the eggs. In order to ensure the synchronous and coordinated motion of this device, when carrying out the prototype installation, the crank must be at 96°, the rocker arm should be at 146°, and the swing arm should be at 174°. The prototype testing indicated that the theoretical analysis and simulation results were in good accordance with the measured value.

Abstract:In order to study the transmission characteristics of electric control transfer in 4WD vehicle, through reading the relevant literature at home and abroad, and obtain the form of actuator, the current research progress of electric control transfer in enterprises and academia, the chain splitter with electronically controlled clutch structure was taken as research object, and a performance prediction method was proposed based on genetic PID control. Firstly, the test bench of electronic actuator was built, including the engine, clutch, transmission, transfer, universal joint, load motor, and other components. The transmission characteristic prediction model of electric control transfer device was constructed by analyzing the power loss of the components of transfer, such as Sprockets, bearings, friction plates and other components. Secondly, the influence of parameters such as clutch friction number, friction plate inner diameter and lubricating oil viscosity on its performance transfer was discussed. The performance test was carried out on the electronically controlled transfer test stand. By completing the test of the engine at different speeds and different torques, the correctness of the test bed was verified. Finally, on the basis of the model of electric control transfer, combined with the seven-degree-of-freedom vehicle model, the PID parameters of the splitter controller were optimized by genetic algorithm, and the driving characteristic prediction model of the electric control transfer in 4WD vehicle during the running process was constructed and simulated under the specific working conditions. The results showed that the model can predict transmission characteristics of transfer during the running process, the friction plate was a key component of the electric control transfer, and the PID control based on the genetic method can suppress the slipping of the wheel, reduce the overall power loss of the car and improve the fuel economy of the automobile. The result can provide theoretical basis for the design of post-control system.

Abstract:Urea selective catalytic reduction (urea-SCR) systems are well known for exhaust gas aftertreatment in power plant applications. Stringent specifications and the dynamic operation mode of such applications demand advanced control strategies. The control purpose of urea-SCR is to simultaneously achieve high NOx conversion efficiency and low ammonia slip. The two emission demands are contradictory. Moreover, owing to the dynamic operation mode of urea-SCR systems, advanced control strategies are required to improve urea injection control. A data-driven predictive controller for urea injection was designed. The input-output data were directly obtained from ETC driving cycle test of the diesel engine bench. The controller was derived by the coupling excitation and separation of the data. Because of the physical characteristics, the input and output constraints were considered explicitly in the problem formulation. In order to obtain offset-free control for the reference input, the predictor equation was gained with incremental inputs and outputs. The experimental test was carried out in ETC and other transient test cycle. The results showed that the controller was able to meet emission control requirements under the excitation test cycle. The closed-loop system had the ability to reject uncertainties caused by uncertainty of working conditions under the non-excitation test cycle.

Abstract:Electrospray technique is one of the reliable approaches to disperse liquid fuels at low flow rate. Heat loss has an important influence on the performance of micro/small scale combustors. Pure ethanol was chosen as liquid fuel, and electrospray technique was applied for fuel dispersion. The combustion and heat loss characteristics were experimentally studied in a small scale combustor with double meshes under the condition of cone-jet mode. The results showed that a round slice flame was anchored near the combustion mesh. Stable combustion was established in the equivalence ratio Φ range of 0.85~1.40. The diameter of the flame was near to the inner diameter of the combustor. The distance between combustion mesh and flame changed with equivalence ratios, which can be seen from the temperature distribution. The larger the equivalence ratio was, the shorter the distance was. Flame temperature and combustion efficiency were all increased firstly, and then decreased as the increase of equivalence ratios. When Φ=1, the highest flame temperature was up to 1197.38K, and the highest combustion efficiency was up to 93.26%. The exhausted gas temperature was decreased and wall heat losses were increased with the increase of equivalence ratio Φ. The exhausted gas temperature was influenced by the distance between combustion mesh and flame. Wall heat losses accounted for 27.25%~33.08% of total heat based on complete combustion of input fuel. Radiation heat loss accounted for about 56% of wall heat losses. Under the condition of Φ≤1, the thermal efficiency of the combustor was near to 69% and then decreased as the increase of Φ. The present combustor with double meshes can realize effective atomization, evaporation and combustion of liquid ethanol at small scale.

Abstract:Aiming to solve the complicated problem of linear driving parallel robot workspace with less study, according to the structure and kinematics model of linear driving parallel robot with the limits of the Hooke joint and the singularity to the workspace, the numerical search method was used to solve the workspace of the parallel robot with the tendency of size, shape, and symmetry of the workspace with respect to the different sets of architectural parameters chosen for the manipulator. A new approach was presented to the architecture optimization of the linear driving parallel robot based on the performance of a weighted sum of global dexterity index and a new performance index-space utility ratio (SUR), and the mathematic model of parameters optimization was set up based on the objective function of this ratio. Particle swarm optimization was used to optimize the parameters of the linear driving parallel robot, the optimal parameters were obtained based on the performance of the space utility index with the global dexterity index in different environments. This method was helpful in designing the linear driving parallel robot and other types of parallel robot. In the end, the laser tracker was used to measure the actual workspace to compare with the theoretical model, which verified the theoretical model of the workspace, laid the foundation for the subsequent optimization of the linear driving parallel robot.

Abstract:Variable stiffness joints are a kind of compliant mechanism to improve the safety of physical human-robot interaction, which has attracted much attention in recent years. Elastic elements are used in the internal kinematic structures of variable stiffness joints. A new mechanically bionic variable stiffness joint using leaf springs was designed. The joint stiffness was adjusted by changing the effective length of leaf springs. By controlling the relative motion of the differential gear train, the position and stiffness of variable stiffness joint can be controlled respectively. Two structures were used in the new joint to exert external forces on the ends of the leaf springs. Based on the elliptic integral solution to large deflection problems of cantilever beams, the effects of two force exertion structures on the joint stiffness property were studied. The simulation results showed that the force exertion structure of the end had great effect on the stiffness during the joint deflection. The joint stiffness was decreased as the increase of joint deflection angle when the force exertion structure was that the external force point was fixed to the joint arm. The stiffness was increased with the increase of deflection angle when the force exertion structure was that the external force point moved relative to the joint arm. The physical experiments of the prototype were conducted to verify the validity of the analysis results. The experimental results showed that the changing range of the joint stiffness was larger. And two force exertion structures can meet the requirements of continuous high stiffness and collision safety respectively.

Abstract:Kinematic and dynamic performances of a robot mechanism is, to some extent, determined by its topological structure, so topological structure analysis and synthesis is an important tool to research and application of robot mechanisms. However, there is still no software for automatic structure analysis of robot mechanisms. The efficiency of manual analysis method is too low and it is difficult to get a complete result. In order to solve this problem, a digital modeling method for topological structure of robot mechanisms was proposed, and the automatic generation algorithm for position and orientation characteristic set (POC) of robot mechanisms was presented. The digital modeling for robot mechanisms was showed, including mathematical description of topological structure elements and the corresponding data structure. Secondly, the essence of POC set was uncovered, and the operation rules of POC for serial and parallel robot mechanisms were formulated based on the theory of linear dependence. Furthermore, the automatic generation algorithms of POC for serial and parallel robot mechanisms were achieved. Finally, five examples were provided to verify the efficiency of the digital modeling method and automatic generation algorithm mentioned above. The digital modeling method for topological structure and automatic generation algorithm of POC presented would be parts of the software being developed for automatic structure analysis and synthesis of robot mechanisms.

Abstract:The development of initial population generation strategy was briefly reviewed. In order to realize the efficient evolution design of customization products, a reasonable model and algorithm was proposed to produce the superior population. Characteristics of the superior population for customized products were discussed. The two remarkable features were that elite individuals should have the similarity of customized requirements and initial genes should be diverse. Based on product gene model, historical product design cases with similar custom genome were obtained by using the angle cosine as clustering statistic, and these cases were used as the initial solution for superior population. Elite individual candidate queue was established by sampling the initial solution members with equal weighted Minkowski distance to achieve uniform population distribution. Difference between the elite individuals genome and the current initial gene library was measured by Jaccard distance. Allele threshold matrix was defined and a diversity allele generation algorithm was built to achieve the diversity of initial population genes. The product fitness evaluation function was established and the dominance of the initial population could be improved according to the feedback result of the evaluation function. The strategy and method were effective in an instance of the product called bridge crane. The experimental results showed that the differentiation of individual queues and the control of multiple gene thresholds could help to avoid premature convergence and obtain high fitness solutions, the proposed approach could take into account both the evolutionary efficiency and the evolutionary quality and increase the success rate of evolution. The strategy was suitable for customized product evolutionary design.

Abstract:A variable-stiffness mechanism using permanent magnet spring was proposed for elastic robots. Due to the motor torque limit, in the case of no increasing in wire tension, strong variable-stiffness was achieved. The permanent magnet variable stiffness mechanism was mainly composed of permanent magnetic spring structure and wire-driven system. The permanent magnetic spring structure was composed of a pair of annular permanent magnets which were arranged in coaxial and the same permanent poles were opposite. The wire-driven system was composed of a movable pulley and two fixed pulleys. The magnetic force of permanent magnetic spring and wire tension of wire-driven system mathematical models were established by virtual displacement method. The magnetic force and wire tension were also measured by experiment. The results of experimental measurement were in good agreement with the calculated results. The calculated and experiment results together showed that the magnetic force, wire tension and stiffness were increased nonlinearly with the decrease of air gap between the permanent magnets, and increased with the increase of axial length and average radius of the permanent magnet. The height of triangle structure of wire-driven system was kept constant, the wire tension and stiffness were increased nonlinearly with the increase of the triangle structure bottom of wire-driven system. Decreasing the radius of the pulley can further increase the range of the wire stiffness.

Abstract:To meet the energy demand of micro-type sensor and real-time condition monitoring system, and reduce the pollution of chemical batteries to water and soil, a piezoelectric airflow energy harvester based on resonant cavity was presented. In order to obtain the vibration state of the fluid in the energy harvester and the deformation characteristics of the piezoelectric transducer when the structure was different, the energy harvesters with different structures were established and simulated by COMSOL, the results showed that the structure of the generator had great influence on the deformation and vibration frequency of the piezoelectric transducer. The influential factors on the harvester properties were analyzed and proof experiments were carried out, the effects of excitation parameters (excitation distance and air pressure) and structural parameters (the length and diameter of the cavity and neck) on the output voltage were obtained. Under other given parameters, there were optimal excitation distance (d*f), length of cavity (l*c) and diameter of hole (d*r) for the voltage to achieve their peaks, besides, l*f/l*c/d*r and the corresponding maximum voltage were increased with the increase of air pressure. In addition, when air pressure was low, there was optimal length of neck to maximize the output voltage, l*r also was decreased with the increase of the air pressure and the corresponding maximum voltage was increased with the increase of the air pressure;on the contrary, when air pressure was high, the output voltage was the maximum without neck, and it was increased with the decrease of length of neck. As a result, the structure and scale of the cavity should be determined according to the air pressure. Under other given parameters, the optimum external resistance (R*) was increased with the increase of the length of neck (lr), and the output power (Pg) was decreased with the increase of the length of neck (lr), the maximum power of the energy harvester was 2.61mW in the process of experiment.