Abstract:Optimization of regional ecological security pattern is the basis of regional ecological security. It is of great significance to analyze and optimize the regional ecological security pattern by using proper models and methods. The optimization of regional ecological security pattern requires the integration of multi-disciplinary synthesis, multi-perspective analysis and the combination of various means. It is generally based on the understanding of the relationship between different landscape types, landscape spatial pattern, landscape process and function. Typically, the impact ways of landscape pattern on the process are found first. Then, a mathematical model is built based on the principles of landscape ecology to optimize land use and local ecological security pattern from multi-level, multi-perspective and multi-disciplinary views. Based on the analysis of domestic and foreign research progress, a summary of the concept development, the evolution of the research content and the optimization methods of regional ecological security pattern was made. And the future research trend of regional ecological security pattern was obtained, including organic integration of multi model, multi method and multi technology, quantitative exploration of regional ecological security standards, public participation mechanism and management methods of interest coordination.

Abstract:An agricultural automatic navigation system was designed on Dongfanghong X-804 tractor to improve the navigation control of agricultural machinery by using RTK-DGPS and double closed-loop steering control. The makeup of the whole navigation system and working principle were presented, among which their main features were: RTK-DGPS could offer positioning data, including heading, roll and pitch parameters, which were acquired from AHRS500GA, and the electro-hydraulic steering controller was developed for automatic steering control. Then, the system control strategy was analyzed and the control transfer function model was developed for trajectory tracking, with a double closed-loop control algorithm for steering system designed according to characteristic of the system nonlinear. The implementation description on an ARM9E-based embedded control system was provided in terms of electronics hardware design. Tests were conducted to examine the navigation system, including a straight line driving test on uneven road, which was to verify the effectiveness of the correction model. The test results showed that the proposed positioning and orientation evaluation algorithm could eliminate the effects of uneven field condition on GPS positioning and the average error of GPS positioning was reduced to 0.43°. Then a test of steering control system was carried out to verify the performance of double closed-loop control algorithm. Test results showed that the steering control system solved the control overshoot well and the average error was 0.40°. Finally, the field test results showed that the performance of automatic navigation system was improved, with average route tacking error was less than 0.019m, average steering angle tracking error was 0.43° and standard deviation was less than 0.041m. The field test results indicated that the proposed positioning evaluation algorithm and double closedloop steering control algorithm on uneven field were appropriated to Dongfanghong X-804 tractor. 

Abstract:Lane detection and tracking algorithm based on active contour model was proposed to solve the poor robustness and realtime problem for vision navigation under factory or agricultural nonlinear illumination conditions. First of all, it was illustrated that navigation problem was equivalent to calculation of polynomial curve parameters, which could describe the navigation lanes. Secondly, the external energy function of active contour model was investigated, including three energy terms. The first energy term was about the Euclidean distance between lane colors and colors on one side of polynomial curve, by minimizing the first energy term could attract polynomial curve to navigation lanes. The second energy term was about the edge features, which could attract polynomial curve to lane edges. The third energy term was about the position difference of polynomial curve between adjacent frames, which could limit curve to change abruptly. Finally, the energy function was simplified to a nonlinear least squares problem, and the Gauss-Newton method as well as the Armijo-Goldstein inexact line search method were used to solve this problem. Home video and independent car were tested, the result showed that the algorithm achieved a navigation accuracy of 98.96% for both the straight lane and bending lane under nonlinear illumination, with average processing time of 40.18ms, and the independent car could walk along the navigation lane successfully. Experiment result showed that the algorithm was robust and real-time.

Abstract:根据玉米定向播种对种粒的要求，设计了一种基于机器视觉的玉米种粒实时精选装置。阐述了装置的组成和工作原理，设计了不合格种粒吹除装置及吹除方案，提出了种粒图像动态检测方法，根据种粒图像RGB颜色特征，提取出种粒区域及其各颜色区域，结合种粒形态特征建立了周长、面积等20个检测指标，并通过测试统计确定了其合格范围，最终据此分析和完成了尖端露黑色胚部、小型、圆形、虫蚀破损、霉变等不符合定向播种种粒的判断。依据种粒粘连处两分界点沿轮廓线较近一侧的距离与两分界点间直线距离之比，大于单一种粒轮廓线上任意两点的对应值，来判断种粒粘连性。试验表明，合格性检测准确率为96%，粘连性判断准确率为99%，不合格种粒有效吹除率为98%。

Abstract:In order to achieve small agricultural automated guided vehicle (AGV) which could navigate autonomously between corn rows, a method was proposed which could quickly and accurately extract the centerlines of middlelate corn rows as the innovative methods of navigation baseline of agricultural robot in field environment. The algorithm was improved by the traditional 2G-R-B algorithm so that it could obtain the characteristics of green plants in real-time and also improve the robustness of image pre-processing. According to the vertical projection of corn crop’s line, points of profile features of corn roots were generated. Using the detection algorithm of peak points, the backup location points of corn roots were obtained and then the location points of corn roots were got after the second judgment and detection. The least square method was used for fitting the location points of corn roots and two lines of crop rows were generated. The actual navigation baseline was calculated based on the formula angle bisector after the line slopes of two crop rows were generated respectively. In addition, the camera calibration process was simplified so that the image pixel coordinates could be converted into world coordinates quickly. The extracted angle and lateral deviation of navigation baselines were used as input parameters of navigation to control agriculture AGV. The experimental results showed that the method had strong robustness which could adapt to different environments and the accuracy of navigation baselines by detecting was more than 90%. The average processing time of a 700 pixels × 350 pixels color image was less than 185 ms which had a better real-time. The results provided a reliable reference method for autonomous navigation of the agricultural AGV in middle-late corn field.

Abstract:When the traditional maize seeder works in the field, the power of seed metering device comes from ground steel. Aiming at the problem that the field conditions are so complicated that the ground steel will skid easily, then the miss index will be increased, an electronic maize sowing control system was designed. The police traffic radar collected the sowing operation speed when the sowing was started, then the control system will calculate the seed metering device rotational speed combined with the theoretical particle distance. The rotary encoder collected the seed metering device rotational speed, then the controller would process speed based on control strategy and obtained the last speed. The optimal process of control strategy can improve the accuracy. The results of the field test showed that when the electronic control seed metering device was working in the field, the average qualified index was 92.40%, which was increased by 3.63 percentage points compared with the traditional sowing. The average miss index was 4.82% and it was reduced by 2.04 percentage points compared with the traditional sowing. The variability of seedspaces was less than 4.20% and the sowing effects were much more than the national standard. When the speed of sowing was more than 10km/h, the effects was worse than other cases, therefore some improvement on the structure to improve the accuracy. The design of the electronic control maize seed metering device provided some definite reference for study of sowing control system. 

Abstract:As one of the key technologies of conservation tillage, subsoiling has been widely promoted in northern China, while the large traction resistance and high energy consumption of subsoiling is the main problem of subsoiling. The structural parameters of subsoiler, which included spade shape, penetrating angle and wingspan angle, had significant effects on the soil property of subsoiling trench and the traction resistance of subsoiler. In order to investigate the effect on the soil physical properties (bulk density, soil porosity and cone index) of subsoiling trench in 0~40cm depth, calculate the subsoiling trench crosssectional area (TCA) and the traction resistance of subsoilers, and make optimization for the key structural parameters of subsoiler, the chiselshape subsoiler (CS), arrowheadshape subsoiler (AS) and wingshape subsoiler (WS) were designed and tested under notillage conditions. Orthogonal experiment was conducted in spring maize ridgetillage area which was located in Zhangwu county, Liaoning province in Northeast China. The trench specific resistance (TSR) of the above three subsoilers had also been calculated. The results indicated that penetrating angle α and wingspan angle β had no significant effect on the change of soil physical properties, TCA and TSR, while the change of α had a significant influence on the traction resistance, and it would be the minimum subsioler when α was 21°. The spade shape of subsoilers affected soil physical properties, TCA, traction resistance and TSR significantly. The soil disturbance extent of subsoiling and TCA were increased in accordance with the order of CS, AS and WS. TCA for WS was greater than those for CS and AS by 49.8% and 30.0%, respectively, and TCA for AS was greater than that for CS by 15.3%（P＜0.05）. However, the traction resistance for WS was greater than those for CS and AS by 123.6% and 36.6%, respectively, and the traction resistance for AS was greater than that for CS by 63.7%（P＜0.05）. TSR was significantly affected by the spade shape, and it was increased with the order of CS, AS and WS. TSR for CS was less than those for AS and WS by 42.4% and 50.2%, respectively, and TSR for AS was less than that for WS by 5.4%. The analysis result showed that if it was just to get relatively more soil disturbance, WS would be the best choice when its penetrating angle αwas 21°. While taking subsoiling trench’s soil properties, TCA and traction resistance, especially TSR into consideration, the relatively best subsoiler was chisel shape subsoiler (CS) when its penetrating angle α was 21°.

Abstract:Ditching fertilization is one of the important links of fruit planting, which is done artificially with large labor intensity but low efficiency, failing to satisfy the requirement of high quality fertilization for modern orchard. The disc-type ditcher is a kind of continuous earthmoving machinery followed by the chain ditcher, which is characterized by high efficiency and convenient operation, and widely used in the farmland water construction and orchard ditching fertilization, etc. But the existing ditching blade has the problems of large power consumption and poor stability of ditch depth. A sine-exponential curve ditching blade was designed through analyzing the advantages and disadvantages of existing blade, using the rotary tillage theory and experimental analysis. Through the analysis of tractor forward speed, rotating speed of the cutter, as well as the influence of their interaction on power consumption and ditch depth stability, the optimal working parameters of the sine-exponential curve ditching blade were as following: tractor forward speed was 1 m/s, rotating speed of cutter was 200r/min. The optimal structure parameters of the sine-exponential curve ditching blade were determined through the three-factor four-level orthogonal test with bending angle and bending radius in B and bending angle in C of the sineexponential curve ditching blade as impact factors, and power consumption and groove depth stability as response value: bending angle in B was 95°, bending angle in C was 140°, and bending radius was 9mm. Through comparing the sine-exponential curve ditching blade with existing blade, it was showed that under the same working parameters and ditching depth, the power consumption of the sine-exponential curve ditching blade was decreased by 3.29kW and ditching depth stability was increased by 8.83 percentage points compared with the existing blade. Index of the technical specifications for the sine-exponential curve type ditching blade is higher than the national standard. The research results provided a theoretical basis for the sine-exponential curve type furrowing blade optimization design. 

Abstract:According to multiarea operations, a kind of overall route planning algorithm for plant protection UAVs was developed in order to reduce flight distance in multi-area operations and operating sequence of each area was reasonable allocation to improve operational efficiency and reduce energy consumption of the UAVs. The algorithm was divided into three parts, namely, single area route planning, operating sequences of areas and dispatching route planning among areas. After analyzing a variety of covering operation modes in aspects of operation distance, extra coverage and missed coverage, the UAVs operation mode in single area was determined. Optimized operation sequences of areas were planned based on genetic algorithm and traveling salesman problem (TSP). Dispatching routes among areas were planned based on improved genetic algorithm with binary coding, finally the overall route planning algorithm was achieved. The simulation was performed in an operation of five different irregular areas, numbers of each area were set as A, B, C, D and E. Operation route of each area was planned by using the previously proposed algorithm of route planning algorithm based on operation path angle in irregular, achieving operation start point, end point and node point coordinates of each area. Operation sequences of areas were achieved based on genetic algorithm and TSP, dispatching routes among areas were planned based on the improved genetic algorithm, of which the code was a random five-digit binary sequence, each digit represented arrangement of start point and end point of each area. The simulation result proved feasibility of the multiarea route planning algorithm. Nowadays, unmanned operations becomes trend, this multiarea route planning algorithm not only saves manpower required by route planning, but also makes operation management easier, and it is suitable for autonomous unmanned aerial vehicles and can be widely used in the area of precision agriculture.

Abstract:When sprayer works in the field, boom movement seriously affected the spray distribution, suspension system is the key device to control the dynamic behavior of boom. The response of a boom suspension should be such that it isolates the boom from high frequency roll of vehicle as it travels over bumpy ground, while transmitting low frequency roll so that the boom can follow undulating and sloping ground. In order to solve the dynamics and control problems of double pendulum active and passive suspension mechanism, considering the coupling effect of vehicle body motion, change of terrain slope, friction of moving pair, etc., a higher order differential equation group was established to describe the dynamic behavior of boom by using the second kinds of Lagrange dynamics equation. Based on this, the dynamic characteristics of the passive suspension were studied, and the effects of these factors, such as damping, friction and pendulum length on the response characteristics were analyzed. A Matlab/Simulink simulation model of active suspension based on hydraulic proportional control was established, and then the influence of gain coefficient, time constant and suspension structure parameters on the boom response and tracking error was revealed. By using Stewart six degree of freedom motion simulation platform and dynamic testing system, step response test and frequency response test were conducted on a spray boom with pendulum suspension, the root mean square error between frequency response test value and the mathematical model predictive value was 0.087. It was demonstrated that the model could be used in the design of a suspension to give a specified response to the rolling motion of the spray vehicle，and the results showed that the model can be used to predict the dynamic response characteristics of the boom, and guide the design of large boom suspension.

Abstract:In order to simulate fixed spray-plate sprinkler water distribution and Christiansen uniformity (CU) under open field conditions, the method for calculating water distribution was proposed by applying droplet size distribution, simulation of droplet distribution utilize droplet trajectory computations and wind-distored model. The accuracy of water distributions of Nelson D3000 spray sprinkler was validated by comparing simulated with observed patterns, it was found that the software appeared to be an effective predictor of sprinkler performance in wind. Under this premise, the water distribution was simulated at different wind speeds with 4.76mm nozzle diameters (24#), the factors, including wind speed, wind direction, sprinkler spacing, working pressure and riser height, which may affect CU, the wind drift and evaporation losses (WDEL) under different working conditions were analyzed. The results showed that sprinkler spacing had the most important influence on CU at 95% confidence interval, and it was followed by riser height and working pressure, wind speed and wind direction did not significantly affect CU. Increasing wind speed, working pressure or riser height indicated an increase in the OWDEL, and working pressure can dramatically affect the OWDEL on account of smashing large water droplet to pieces. Using this sprinkler, the lateral moving irrigation system can attain a high uniformity coefficient at 2.13~3.14m sprinkler spacing along the lateral when the wind speed was lower than 6m/s, and with this range of mounting spacing, increasing sprinkler riser height or working pressure cannot promote a higher CU distinctly, low working pressure was recommended considering little cost in the design of the sprinkler irrigation system. In addition, decreasing the riser height can reduce WDEL effectively, in order to increase water use efficiency, low height cooperated with plant height was reasonable.

Abstract:In recent years, the rapid growth of wine industry in China is promoting the increase of vineyards. However, the wine grapes are harvested entirely depending on hand picking in China with high cost. The old harvesting method restricts the widespread popularization and planting of wine grapes. Research on picking machine and picking mechanism of wine grapes is in its infancy in China. A study was conducted to change the artificial harvesting status of wine grapes, promote the mechanization of wine grapes thread mechanism, and establish the theoretical guidance and design basis for the picking machine of wine grapes under Chinese national conditions. In previous studies, single bunches of grapes threaded by flexible bow teeth had been certificated to be feasible. As the process of harvesting is quite complex, it needs to be studied further. Therefore, kinematic and dynamic analyses of the harvesting process were carried out to further study on threshing mechanism, and there were three factors, including rotating speed, helix angle and travel speed, which were proved to be important to harvesting. Then the walking ability test bench of indoor harvesting which could be used to study a variety of potential effective factors and new type of threshing devices was designed and orthogonal experiment was conducted. The evaluating indicators of this test were threshing rate and breakage rate, the factors of this test were rotating speed, helix angle and travel speed, and the samples of this test were the Cabernet Sauvignon. The test result showed that only rotating speed and travel speed can influence the threshing rate to a certain extent. With the increase of rotating speed from 200 r/min to 300 r/min, the threshing rate was increased from 75.7% to 92%. With the increase of travel speed, the threshing rate was decreased from 94.7% to 78%. Moreover, for the breakage rate, the effects of three factors were not significant and the breakage rate was maintained at about 20%. This study provided a reference for design and improvement of the flexible comb.

Abstract:The whole stalk cutting-placementing machine of staminate plant was designed to improve the mechanical level during the seed corn cultivation. The machine consisted of cutting mechanism, stalk conveying mechanism and hydraulic driving system. The cutting mechanism was featured with a supportless revolving cutting design with an inclination cutting angle. To fully cut the plant, the revolving angel velocity of blade was figured out by considering the parameter of flat blade. A blade kinematic study was conducted to work out the conditions that preventing omitting, and the reasonability of blade structure was proved. Stalk conveying mechanism was constituted of round conveying chain with long and short clamping device installed and compression bar. The test on stalk forcing and conveying kinematic analysis showed that the technical parameters were obtained while stalk could be steadily held and conveyed effectively. Stubble height can be adjusted by a parallelogram design drived by hydraulic cylinder. Blade and conveying chain were motivated by the loadsensing hydraulic system. Field experiment proved that the whole stalk cutting-placementing machine of staminate plant was reliable and highly efficient with a 100% cutting ratio and the orderliness ratio was higher than 95%, which sufficiently met the staminate plant cutting requirement. 

Abstract:As one of the most important working components of harvester, the cutting performance of cutter directly affects the quality of crops harvest and the subsequent transportation effectiveness. The reciprocating cutter structural parameters of the selfdesigned Artemisia selengensis orderly harvester and the physical parameters of Artemisia selengens is were studied, the three dimensional entity model of cutter and flexible simplified model of crop stem were built by software Pro/E, and the coupled dynamics simulation analysis was proceeded through dynamic analysis software ADAMS according to the parameters acquired. The cutting speed vg, cutting angle α and working speed vm of the cutting system were selected as factors, the cutting force F and recutting ratio γwere selected as evaluating indicators to design a virtual orthogonal experiment with three factors and three levels. The response surface methodology (RSM) regression analysis and variance analysis were applied to analyze the results, and compared with the test results of field experiment. The results showed that RSM optimum combination was vg=1.6 m/s, α=15°,vm=1.0m/s, cutting force F and recutting ratio γ were effectively reduced with this combination, the comparison results showed that the cutting force error was less than 10.9% and the recutting ratio error was 11.3%, indicating the effectiveness of the simulation analysis and regression forecasting model. The study illustrated that the reciprocating cutter designed could satisfy the demands of Artemisia selengens is orderly harvest, and had a certain reference value.

Abstract:The pressure fluctuation experiment was conducted and the entire flow field of mixed-flow pump was simulated by large eddy simulation (LES) with standard Smagorinsky subgrid scale model to investigate pressure fluctuations and mixedflow pump inner flow under low flow conditions. The experimental results indicated that the multiples of pressure fluctuation at the impeller inlet was the highest and it was increased when the flow rate was decreased. the main pressure fluctuation frequencies at the impeller inlet，impeller outlet and vanes inlet were blades passing frequency under different conditions, however, the main pressure fluctuation frequencies at the vanes outlet was changed under different conditions. The large eddy simulation results indicated that the flow conditions at impeller inlet was better and axial velocity was changed small under 0.8Qopt(Qopt, operating condition). Under 0.4Qopt, however, the flow conditions at impeller inlet became complicated, therefore, the axial velocity was changed significantly. The angle of attack of the fluid on the blades was increased and affected by tip leakage flow. The flow separation was generated at the leading edge of suction surface at t* =0.0416, when the impeller was rotated from t*=0.0416 to t*=0.1249, the flow separation was intensified and the swirling strength of the separation vortex was gradually increased, so the static pressure of the leading edge of suction surface was decreased, the adverse pressure gradient was increased which promoted the generation of backflow. When the backflow reached the leading edge, the static pressure of leading edge was gradually restored，therefore the flow separation was an important reason that making the multiples of pressure fluctuation increased.

Abstract:Two-direction tubular pump device can be adopted to meet the drainage and water transfer, so it was often used along Yangtze River and sea area. The analysis of hydraulic performance and internal flow becomes research hotspot. The twodirection tubular pump device consists of inlet flow passage, two-direction impeller, straight blade guide vane and outlet flow passage. In order to analyze the effect of guide vane position on hydraulic performance and flow pattern, the CFX14.5 was used to obtain the steady flow field in pump device of six different guide vane positions under positive and reverse conditions. The SST model was chosen, and mass flow rate and total pressure were set at inlet and outlet, respectively. The interfaces between inlet flow passage and impeller, and between impeller and guide vane were set as “Frozen Rotor”. The interface between guide vane and outlet flow passage was set as “None”. In addition, a smooth wall condition was used for the wall function. The results showed that good agreements between simulated and experimental results can be obtained, and the maximum relative error was less than 5%. Under positive rotation, for part-load condition, the efficiency was declined with the increase of guide vane position S and the maximum loss value in diffuser passage can be observed when S was 40mm. However, for over-load condition and design condition, the efficiency was increased with the increase of S and the minimum loss value in diffuser passage can be obtained when S was 100 mm.Under negative rotation, the effect of guide vane position on hydraulic performance was not obvious. In summary, the guide vane position S with value of 100mm was optimal. The results can provide reference opinion for two-direction tubular pump device.

Abstract:With rapid urbanization and industrialization, rural work forces have migrated to cities, leading to remarkable reduction in rural poulation. So large amounts of arable lands have been abandoned in China in recent years. Abandoned arable lands in under development region of China have seriously affected the redline of arable land and national food security, which has become a major practical problem facing urban-rural integration. Multispectral remote sensing has the advantage of wide range and high speed in terms of data acquisition. It has great potential in the study of lands use. A new research approach and technical roadmap were proposed for abandoned land information extraction based on remote sensing, geographic information system, support vector machines and landscape ecological index. The study area, Zilu town, Henan province, China, is a typical underdevelopment region. Four scenes Landsat-8 OLI data from 2013 to 2015 were used to extract abandoned arable land, and its spatialtemporal distribution was analyzed based on landscape metrics. Furthermore, analysis of driving factors was conducted, such as terrain, traffic, irrigation conditions and farming radius in terms of the impact of abandoned arable lands in the study area. The results showed that the accuracy of extracting abandoned arable lands using RS was above 90%. The area of abandoned arable lands was divided into seasonal and perennial abandoned, and the former was more severe. The factors of terrain, traffic, irrigation conditions and farming radius affected the spatial-temporal distribution of abandoned arable lands, and the slope of the terrain had the greatest impact. The results can provide technical support for spatial information extraction of abandoned arable land in underdevelopment region, and can be applied to establishment of regional sustainable development policy.

Abstract:Analyzing the characters of spatial distribution in cultivated land quality of Beijing-Tianjin-Hebei region is important to protect and coordinate the development of regions. The mean grade in each index area was calculated with annual database of 2013 about the cultivated land quality by using the weighted average method. Moreover, the deviation between grades was calculated by mean dichotomy method and grade dispersions in each counties by variance. The results showed that the mean grades were under 8 and the cultivated land qualities were lower than the national average of 9.8. Particularly, the average grade of Beijing was slightly higher than those of Tianjin and Hebei. Physical quality grade deviation was ranged from -3.08 to 4.90, and utilization quality grade was ranged from -5.97 to 5.16, economic quality composition grade was ranged from -5.99 to 4.24.The deviation of cultivated land quality grade for more than 80% of the region was within ±2. The utilization quality grade variance was ranged from 0 to 6.13. The plain areas had large variances and the plateau areas had small changes. The results of space difference analysis showed that the physical quality of cultivated land was slightly better than that of plain areas, but its utilization level and economic efficiency were obviously different. The western mountains area, northern mountains area and Bashang Plateau area had high potential to increase the cultivated lands qualities, although the natural condition and infrastructure should be enhanced. The mean dichotomy was proposed to set cultivated land quality goals after land consolidation. And the variance was put forward to divide land consolidation region, which can be a reference for choosing priority zoning. The research could be referred for well-facilitated farmland construction, improvement of medium or low-yield cultivated land and selection of priority zone.

Abstract:Land consolidation can excavate the potential of arable land quality effectively. In order to calculate the potential of arable land quality scientifically and reasonably and guide corresponding land consolidation projects, a new method was proposed based on limiting factors and hot spot analysis. Zhuozhou city was chosen as the study area for experiment with space grid as basic unit. Firstly, element association method was used to analyze factors influencing arable land natural quality. Secondly, an index system was established to response to arable land utilization level and calculated one by one, and then hot spot analysis was adopted to find low values cluster area. Thirdly, land consolidation projects were carried out to figure out the influence of changes of limiting factors and improvement of indicator values. Eventually, potential of arable land quality was calculated to examine the effects after limiting factors changing and indicator values improving. The results showed that physical quality grade index could be improved by an average of 408. Irrigation was the top limiting factor of arable land natural quality and the overall utilization levels of arable lands in Zhuozhou city were varied widely with the characteristics of both eastern and western areas being higher than that of the central region. It was put forward to carry out water-saving irrigation in low irrigation areas and to carry out corresponding measures in cold spot cluster areas, such as building arable land roads, arable land shelterbelts and irrigation systems. Statistically significant cold spots of arable land space form score located in north-central areas, these areas should strengthen arable land leveling. Statistically significant cold spots of rural roads located in northern and western areas, these areas should be recommended to strengthen the construction of roads. Statistically significant cold spots of ditches throughout the central region of Zhuozhou, from south to north, these areas should strengthen the construction of ditch. The method proposed was helpful to determine the limiting factors，divide zones of arable land consolidation and provide relevant measures. The result was an important gist for regional land consolidation planning, land consolidation project as well as land consolidation zone dividing.

Abstract:In order to further promote the overall planning and coordination configuration of arable land in Beijing-Tianjin-Hebei region, the space control and comprehensive upgrading mechanism is implemented about arable land quality, and the demand of coordinated development of arable land resource needs to be ensured. Fractal characteristics of spatial distribution of arable land quality in Beijing-Tianjin-Hebei region and its mechanism were studied by the combining means of GIS, fractal theory and grey relational grade analysis. Main conclusions can be drawn as: in Beijing-Tianjin-Hebei region, the quality of arable land showed a trend with certain regularity in space with the characteristics of obvious differences between the north and the south, which was high in south and low in north, low in regional edge, and high in middle region. There was less arable land but good quality in Beijing and Tianjin and a large number of arable land in Hebei; but the quality was generally not high. The fractal theory can be used to study the structural characteristics of the spatial distribution of arable land quality, fractal features represented the spatial form complexity and spatial occupation of arable land quality in Beijing-Tianjin-Hebei region. The spatial structure of Beijing-Tianjin-Hebei region was the simplest with the most stable form and the highest quality, and its space occupying was the highest at the natural quality level. While at the economic quality level it was remained the lowest; the spatial structure and stability of medium land were in the middle, but the space occupying was the largest; spatial structure complexity, the stability of space form and the space occupying of low quality arable land were opposite to the higher quality arable land. The main factors that affected the fractal characteristics of arable land quality were the natural conditions, such as light, temperature and climate, based on this, agricultural production conditions and socio-economic conditions disturbed its fractal characteristics further.

Abstract:Up-scaling method for inferring spatial information from a pixel scale to a basic unit scale has significant effects on aggregating results and decision-making. Therefore, developing appropriate methods to accurately up-scale spatial data is the key to infer useful drought information. The time series of vegetation temperature condition index (VTCI) drought monitoring results in Guanzhong Plain from early March to late May in the years from 2008 to 2013 were spatially transformed from a pixel scale to a basic unit scale by using the dominant class variability-weighted method (DCVW), arithmetic average variability-weighted method (AAVW) and median pixel variability-weighted method (MPVW) in the distributed mode and aggregated mode to obtain the aggregated VTCIs. The weighted VTCIs of winter wheat in main growth period were calculated, and the regression analysis between the weighted VTCIs and winter wheat yields was applied as references to evaluate up-scaling methods. The results showed that the regression analysis results of the three methods in the distributed up-scaling mode were generally better than those in the aggregated upscaling mode. The regression analysis results in the distributed up-scaling mode also indicated that the computing accuracy was high by DCVW and AAVW and was low by MPVW. DCVW in the distributed up-scaling mode was the most accurate method with the highest determination coefficient and the lowest estimated standard error, which were 0.64 and 289.97kg/hm2, respectively. The estimation yields of winter wheat which obtained by DCVW were very close to the levels of statistics yearbook of Shaanxi Province, indicating that the estimation precision of DCVW mehtod was high, and the method was robust. Overall, the method of DCVW in distributed up-scaling mode was the most reasonable approach to up-scale VTCIs in Guanzhong Plain from a pixel scale to a basic unit scale.

Abstract:It is an important way to understand the change of land resources and the environment by studying vegetation dynamic change and spatial-temporal evolution, which has important sense to improve the ecological environment scientifically. The spatial-temporal variation of vegetation cover in the Yellow River Basin was analyzed with mean method, variation coefficient method, trend analysis method and Hurst index, based on GIMMS-NDVI time series data (1982—2013). The results showed that the peaks of monthly average NDVI over the last 32 years were occurred mainly in the period of May to September from 1982 to 2013 in the Yellow River Basin, and the maximum was 0.546 in August. In annual variation, the vegetation cover had an increasing trend at the rate of 0.018/(10a). In the NDVI variation, the low fluctuation of NDVI was in leading position in the Yellow River Basin during 1982—2013, the area with variation coefficient less than 0.1 accounted for 53.88% of the total area. In spatial distribution of annual average of NDVI, the vegetation distribution pattern presented a stepped increasing trend from north to south. The area with mean annual of NDVI less than 0.4 accounted for 24.65% of the total area in the Yellow River Basin, and about 45.73% in better vegetation cover with mean annual of NDVI more than 0.6. In changing trend, as a whole, the vegetation cover showed a trend towards improvement over the last 32 years in the Yellow River Basin. Areas showing a trend towards improvement accounted for about 59.49% of the total area, and the area with no change accounted about 33.96%. In sustainable changes, the future changing type of vegetation cover would be unchanged and continuously improved, which accounted for 33.56% and 58.81% of the total area in the Yellow River Basin, respectively.

Abstract:Point cloud obtained from terrestrial laser scanner contains detailed, high precision three-dimensional(3D) surface coordinates, which is of special importance for forest parameter estimation and accurate reconstruction of plant model. An improved method for tree branching structure reconstruction was proposed based on the fact that a clean partition of branches and leaves form tree point cloud was very difficult if it was not impossible. Firstly, principal direction at each point was estimated with chord and normal vectors (CAN), and point cloud from the branches and leaves was separated by using both the similarity of principal direction between neighboring points and distribution density of points. Secondly, skeleton nodes and corresponding radii were computed from main branches by using level sets and least square method. For the leaves, the crown volume was divided into equal-sized voxels, all the points in a voxel were represented by the voxel’s centroid, and all centroid points formed feature points of the crown. Finally, tree model was reconstructed by cylinder fitting based on the topology of skeleton nodes and feature points. Segmentation results accuracy analysis and four different tree species model reconstruction examples were introduced. Segmentation accuracy analysis and model reconstruction quality evaluation showed that the approach was robust and insensitive to noise; the reconstructed tree models were in good agreement with the point cloud. The method was also able to extract structural parameters, including tree height, diameter at breast height (DBH) and volume parameters.

Abstract:Downy mildew is one of the most common diseases suffered by greenhouse cucumbers, which may decrease the quality of greenhouse cucumbers and cause great economical loss to the farmers. In order to increase the accuracy of downy mildew diagnosis for greenhouse cucumbers, a downy mildew diagnosis system for greenhouse cucumbers was designed based on image processing. Focusing on the disease spots images captured in greenhouse field, the conditional random fields (CRF) based on segmentation method was utilized for the system to achieve disease spots images. When building the CRF model, decision tree model was used to extend unary potential function, which could effectively improve the accuracy of segmentation. The post-segmentation images and the disease spots images were transferred to HSV color space, and then 25 features, including color, texture and morphology features, were extracted. A subset of features was generated by rough set method. Finally, the RBF based SVM was used for the system to identify the greenhouse cucumber downy mildew. Taking cucumber downy mildew images obtained in greenhouse from agricultural innovation base of institute of plant protection, Tianjin academy of agricultural sciences as an example, the system was tested. The results showed that the segmentation method used by the system could effectively segment the disease spots images, which managed to overcome the noise caused by the illumination and complex background. A subset of 12 features was obtained by rough set method from the original feature set of 25 features, which improved the efficiency of the system. The identification accuracy of cucumber downy mildew reached 90%, which indicated that the downy mildew diagnosis system could meet the requirement of identification for greenhouse cucumbers.

Abstract:In order to detect rice blast rapidly and accurately, chlorophyll fluorescence spectra of early rice blast were analyzed on leaf level, and the identification models of rice blast were established. Rice leaves were inoculated with rice pear spore first, and chlorophyll fluorescence spectra were achieved respectively at three stages of inoculation before (0h), gley period (48h) and disease spots early appearance (7d). Meanwhile, variation characteristics of chlorophyll fluorescence spectra at three stages were analyzed, Savitzky-Golay (SG) and the first derivative transform (FDT) were applied to reduce the noises and obtain the characteristics of chlorophyll fluorescence spectra. Then the method of Gaussian function fitting (GFF) was used to achieve the dimension reduction on spectral information, and multiple feature vectors of each band were extracted. Furthermore, the spectral data were divided into calibration set and validation set. Taking three stages of early disease as rice blast levels, and comparing four classic kernel function，support vector classification (SVC) models were established respectively with full bands feature vectors and composite bands feature vectors based on calibration set, and the models were tested with validation set. The results indicated that chlorophyll fluorescence spectra of blue green region, red and farred region were changed with the change of severity of early disease, GFF-SVC model with SG-FDT pretreatment for three stages disease had the highest classification accuracy rate, and the recognition results of different bands combination of primary spectrum, SG spectrum, SG-FDT spectrum were different for rice blast.

Abstract:Behavior of livestock in a pasture needs to be detected, and motion path and location information of livestock need to be collected in the intelligent pasture management, the acquisition of the above information can be realized by using the pasture Internet of things. The system architecture based on wireless sensor network can meet the communication requirements between different sampling nodes. However, because the location of a pasture is generally remote and network environment is complex, interruption and packet loss often appear in the connection with Internet. Using the traditional network connection mode can lead to a large number of data loss. In order to reduce the loss of sampled data in connection with Internet, a data transmission scheme based on opportunistic network is presented. Moreover, the communication status of sensors in a pasture environment is analyzed and three communication ways between sensors are summed up, which are modeled and analyzed respectively. Under the premise of the sensor limited storage capacity, the calculation method of accessing point density is put forward by using the principle of opportunistic network, and the relationship between livestock movement speed, sensor node storage capacity and data transmission loss rate is summarized, so as to ensure the system data loss in the design to allow for the range. Finally, an experimental evaluation and validation of the theoretical results of the method is given to prove the correctness of this program.

Abstract:In order to achieve high-precision prediction of temporal and spatial distribution of the groundwater level in shallow groundwater cones region, a model was constructed firstly based on extreme learning machine (ELM). By choosing different combination factors of groundwater recharge and discharge as the input parameters of model and observing data of 28 wells as predicted target in Shijiazhuang plain, the error of spatial distribution trend was analyzed by using ArcGIS software. The results showed that the ELM model based on the water balance theory could accurately reflect the non-linear relationship of groundwater system under the influence of human and nature activity. The root mean square error (RMSE) of model under the condition without exploitation or precipitation as input factor was two times higher than that under the condition without other factors, and the coefficient of efficiency (Ens) and coefficient of determination (R2) were further reduced. Compared with the BP model, the RMSE of ELM model was reduced by 43.6%, and the scope of error was reduced by 46.4%. Ens and R2 were improved to 0.99. The tendency of error distribution showed that it was decreased from the south and southeast to the central. The RMSE of ELM model was obviously lower than that of BP model in all the regions. The accuracy of ELM model (RMSE was less than 1.82m, Ens was higher than 0.95) was higher than that of BP model (RMSE was more than 3.00m, Ens was less than 0.85) in southern high error region. Therefore, exploitation and precipitation were the main impact factors on the groundwater dynamic in the model. Meanwhile, the stability, accuracy and space uniformity of ELM model were better than those of BP model. And the transplantation results of ELM model were more satisfactory. The model could be used to forecast groundwater level of other unknown wells based on given data. Therefore, the ELM model could be used as a recommended model for predicting groundwater level under conditions of missing hydrogeological and groundwater recharge data.

Abstract:One of the problems that exists in substrate culture is salt accumulation in root zone, and adequate management of nutrient solution is the primary method to control it. In order to achieve scientific management of nutrient solution, salt accumulation characteristics in root zone need to be studied. A greenhouse experiment was carried out to determine the influence of two systems (open and closed) on electrical conductivity, ion constitution of root solution, nutrient uptake, yield and fruit quality of tomato and nutrient use efficiency. Results showed that electrical conductivity of root solution was increased with the growth of tomato, the highest electrical conductivity in open and closed systems were 11.9 mS/cm and 17.2 mS/cm, respectively. The salt ions in root zone of the two systems were mainly NO3-, K+, Ca2+, Mg2+,SO42- and H2PO4-. The ion imbalance was found in both the open and closed systems, ratios of K+,Ca2+ and H2PO4- concentrations to total ion concentration were decreased from the initial while the ratios of Mg2+, NO-3 and SO42- were increased. The yield of tomato was decreased with high electrical conductivity in open and closed systems, while the blossom-end rot (BER) of fruit was increased with high electrical conductivity and ion imbalance degree. At the end of the trial, the BER in open and closed systems were 29.7% and 36.6%, respectively. Compared with open system, closed system improved the nutrient use efficiency, the nutrient use efficiencies of N, P, K, Ca, Mg and S were increased by 11.6%, 19.6%, 18.9%, 11.8%, 37.3% and 15.9%, respectively. In conclusion, the salt accumulation and ion imbalance existed in open and closed systems. Increasing the input of K and P while controlling the use of Mg, N and S could help to keep the ion balance of root solution. The closed system was a more promising way to realize environment-friendly, water-saving and fertilizer-saving in substrate culture.

Abstract:Water transport through soil-plant-atmosphere continuum was a complex process, which was regulated at a variety of organizational and time scales. Quantification of the relationship between environmental factors, biophysical regulation and transpiration was critical for improving water use efficiency. Taking soil moisture, air temperature, relative humidity and photosynthetic active radiation as experimental factors, a composite quadratic orthogonal regressive rotation design of four factors and five levels was applied to characterize the coordination between environmental factors that driving and regulating transpiration of muskmelon. Soil moisture was maintained by weighing method and environmental factors were controlled by growth chambers. Transpiration and physiological parameters were determined under different combinations of environmental factors. According to stomatal behavior and vapour diffusion, a transpiration rate model was developed. Stomatal conductance was simulated by using Jarvis model with multiple environmental factors as model inputs. The proposed transpiration model had satisfactory performance with only meteorological input requirements, and thus it was an effective approach for calculating crop transpiration for greenhouse grown muskmelon. Characterization of main effect, single effect and marginal effect of environmental factors was determined. All of the environmental factors were positively correlated with transpiration rate except relative humidity. Correlation between transpiration and soil moisture, temperature can be described in linear functions with positive slopes. Whereas photosynthetic active radiation exhibited parabolic functions with transpiration rate. Relative humidity was negatively linked with transpiration. The present results demonstrated that environmental factors were tightly coupled with water transport. Coupling effects between two environmental factors were quantified by regression model, with other factors were uniformity maintained at a constant level. Individual contribution of soil moisture and air temperature in improving transpiration was enhanced by their coupling effects, which may be attributed to the larger driving force for water transport caused by the enhanced water potential gradients between soil and atmosphere. Therefore, transpiration was maximized, with increased soil moisture and air temperature. Relative humidity was negatively linked with vapor pressure deficit, thus the driving force of water flow at leafatmosphere interface was suppressed with the relative humidity. Physiological roles of soil moisture or air temperature in promoting water flow were significantly suppressed when coupled with relative humidity. Photosynthetic active radiation was not significantly correlated with other environmental factors in mediating water transport through soil-plant-atmosphere continuum. Coordination between hydraulic conductivity and stomatal sensitivity performed significant roles in maintaining a balance between vapour and liquid phase water transport. Hydraulic conductivity and stomatal conductance followed similar patterns with the increase of soil moisture, temperature and photosynthetic active radiation. Hydraulic conductivity and stomatal conductance were at maximum values when leaves were exposed to optimal ranges of environmental factors. It was demonstrated that the response of plant transpiration to environmental factors was not only determined by its individual function, coupling effects between environmental factors and physiological regulatory systems also performed significant roles in modulating water driving force. These observations provided novel information for improving water use efficiency of greenhouse grown muskmelon. Mechanism of environmental factors in regulating plant transpiration was explored under controlled environment by using growth chamber, which needed a further examination under greenhouse growth condition.

Abstract:To study the effects of long-term conservation tillage (no-tillage and subsoiling) on nitrogen accumulation and translocation characteristics of winter wheat, a ten year (2006—2016) field experiment was carried out, and the effects of different tillage treatments, including traditional tillage, no-tillage and subsoiling on the soil water content in 0~100cm during the key winter wheat growth stages were analysed. The results showed that long-term no-tillage and subsoiling treatments significantly increased the soil water content in 0~100cm and no-tillage treatment was superior to subsoiling treatment in the dry year. The nitrogen distribution ratio in stem and leaf was gradually decreased, while it was gradually increased in wheat are from flowering to harvesting stage under three tillage treatments. Compared with conventional tillage treatment, average nitrogen accumulation amounts in stem, leaf and ear under 2-year continuous notillage treatment were increased by 44.3%, 80.5% and 70.9%, respectively, and there was no significant increase under 2-year continuous subsoiling treatment at flowering stage. At harvesting stage, no-tillage and subsoiling treatments significantly decreased the nitrogen accumulation in stem, while significantly increased its ear accumulation amount compared with conventional tillage treatment. Moreover, notillage treatment significantly increased the nitrogen translocation amount of winter wheat vegetative organs, translocation ratio, contribution ratio to grain (P<0.05), while subsoiling treatment was non-sustainable to increase nitrogen translocation amount and ratio. In general, long-term effect of no-tillage treatment on nitrogen translocation of winter wheat was superior to that of subsoiling treatment, especially in the dry year.

Abstract:For a long time, the soil of artificial forest land in the loess hilly-gully region was continued to be dry, which had serious impact on the subsequent vegetation. Studying on jujube growth in the dry soil had important significance to realize forestry sustainable development in this region. Four different initial soil volumetric water content levels were set for the experiment in the open air, and the same water-saving type pruning was used to keep consistent specifications. Soil moisture, jujube growth and yield for two consecutive years were tested under a completely natural rainfall condition. Results showed that the soil moisture was tended to be a fixed value for different initial soil moisture contents under natural rainfall. And this value was depended on rainfall. Normal precipitation year soil moisture was steady at (13.83±0.22)% in 2014, partial drought year soil moisture was steady at (9.46±0.32)% in 2015. Different initial soil drying degrees would significantly inhibit the growth of branches and jujube fruit number. Jujube growth under the same dry soil was depended on rainfall. The yield under water-saving type pruning technology was 36%～41% higher than that of conventional dwarf pruning, water use efficiency was increased by more than 3.6 times. Water-saving pruning techniques would improve jujube water use efficiency. This research can solve dry jujube soil water shortage in the loess hilly-gully region and provide new basis for achieving sustainable development. This research had the important theoretical significance and value in practice.

Abstract:In order to obtain the optimum geometrical parameters for improving the anti-clogging performance of labyrinth flow path of drip emitter,16 kinds of flow paths were designed according to the structural parameters such as angle, height, upper base, offset and width. An Eulerian-Lagrange liquid-solid multiphase turbulence model combined with the kinetic theory of granular flow was used to carry out simulation based on coupled CFD-DEM water-sand two-phase flow in drip irrigation emitter, which analyzed the pass rate of sand group, the percentage decrease in speed of sand, the movement and distribution regulars and force and so on. The result indicated that the clogging performance of labyrinth channel could be expressed by the pass rate of sand. There existed a negative relationship between the pass rate and percentage drop of sand group speed . The speed descending of sand movement was the key factor that affected the sand pass rate in labyrinth channel. The angle and width were the main structural parameters of flow passage that affected the water flow characteristics. The speed of sand particles depended on the flow characteristics of the flow channel, and the angle had a significant influence on sand speed. Sand was always drawn by drag force from water flow in the optimum structure. Most of the sand ran in the mainstream area, so they maintained high movement speed. Little sand lost kinetic energy, thereby it reduced the blocking probability. This method was applied to analyze movement and distribution of sand group, understand the movement of sand from micro-view perspective, and it had become an efficient technique in structural design of labyrinth channel.

Abstract:When trying to analyze water resources supply and demand balance under climate change for river basin and irrigation district, the annual runoff of river and its monthly distribution in representative hydrological years are necessary and basic data to evaluate the available surface water supply. In order to predict the impacts of future climate change on runoff of Jinghe River, a SWAT model was developed by collecting and processing large amounts of data such as the hydrological, geological and meteorological data. The model was calibrated and validated by using 11 years monthly runoff data from Zhangjiashan hydrological station and evaluated with two targets (the Nash-Sutcliffe coefficient (Ns) and determination coefficient (R2)). Values of Ns and R2 in calibration and validation stages were both greater than 0.7, which meant that the model was capable of simulating runoff responses to climate change. Three representative hydrological years were chosen after analyzing and calculating the precipitation frequency, which were the wet year (25%), normal year (50%) and dry year (75%). Two future climate change scenarios were developed based on previous study, in which precipitation and temperature trends of future three periods (2020s, 2050s and 2080s) in Jinghe River were predicted by statistically downscaling the output data of HadCM3 under A2 and B2 scenarios, and the river annual runoff and its monthly distribution for representative hydrological years in three future periods were forecasted. The results showed that the annual runoff of representative hydrological years in three future periods of both scenarios were decreased, comparing with base years. The changing rates were 26%～42% and 25%～35%, respectively in wet year, 23%～37% and 21%～25% in normal year, 23%～38% and 20%～31% in the dry year. Under both scenarios, the distributions of monthly runoff of representative hydrological years in three future periods had the same trends as base years. And the changing trends of monthly runoff were basically conformed to the tendencies of monthly precipitation in corresponding scenarios and times. The major amplitudes of monthly runoff were appeared in the peak. In scenarios A2 and B2, the changing rates of peak value in three future periods respectively were 41%, 43%, 61% and 34%, 37%, 56% in August of the wet year, 15%, 23%, 38% and 21%, 18%, 31% in July of the normal year, 20%, 36%, 46% and 24%, 31%, 28% in June of the dry year. But the monthly runoff of February in three future periods under scenario B2 was increased from 17.71m3/s to 24.93m3/s, 38.79m3/s and 63.63m3/s, respectively. By calculating the nonuniform coefficient of the runoff annual distribution (Cvy), it was showed that the value of Cvy in wet year was decreased from 1.06 to 0.71 (scenario A2) and 0.74 (scenario B2).

Abstract:In order to investigate the optimal scheme of irrigation and nitrogen application for winter oilseed rape (Brassica napus L.), two-year (2013—2014 and 2014—2015) barrel experiments were conducted to evaluate the effects of different irrigation and nitrogen applications on aboveground dry matter and nitrogen accumulation during reproductive growth stage, seed yield, evapotranspiration (ET) and water use efficiency (WUE), and then determine the yield response factor (Ky) of winter oilseed rape. The experiments included three irrigation levels (W0: (50%~60%)FC, FC denoted field capacity; W1: (60%~70%)FC; W2: (70%~80%)FC) and three nitrogen levels (N0:0g; N1: 1.2g;N2: 2.4g).The results showed that W1N1 could obviously improve aboveground dry matter and nitrogen accumulation during reproductive growth phase, seed yield, and WUE of winter oilseed rape. However, excessive irrigation or nitrogen (W1N2,W2N1 and W2N2) would not significant increase the aboveground dry matter and nitrogen accumulation, seed yield, and WUE in comparison with W1N1. W2N1 achieved the highest seed yield across the two years, while W1N1 obtained the highest WUE. Though no significant differences of seed yield and WUE were found between W1N1 and W2N1, the ET in W1N1 was significantly lower than that in W2N1. In addition, seed yield and WUE were all showed a significant quadratic parabola relationship with ET, and the Ky of winter oilseed rape was 1.36. In comprehensive consideration of seed yield, water and fertilizer conservation, W1N1 treatment was recommended as an appropriate irrigation and nitrogen application schedule for winter oilseed rape in the study area.

Abstract:A field experiment was conducted to investigate the effect of varying supply methods of nitrogen and irrigation on dynamics and distribution of soil nitrate nitrogen during maize (Zay mays L., cv. Gold northwestern 22) growth in Northwest China. Irrigation methods included alternate furrow irrigation (AI), fixed furrow irrigation (FI) and conventional furrow irrigation (CI). Nitrogen supply methods included alternate nitrogen supply (AN), fixed nitrogen supply (FN) and conventional nitrogen supply (CN), which were applied at each irrigation. Maize rows were established in west-east direction. Soil nitrate nitrogen content in south and north of the plant was measured in 0~100cm soil depth (20cm as an interval) before planting and at 6 collars, 12 collars, tasseling, filling and maturity stages. The results showed that spatial-temporal distribution of soil nitrate nitrogen in south and north of the plant was influenced more by varying methods of nitrogen supply and irrigation compared with that under the plant, so did that in 0~40cm soil depth compared with that in 40~100cm. At filling stage, soil nitrate nitrogen of irrigated side was moved down to 60~100cm soil depth for FI coupled with FN when nitrogen and water were applied within the same furrow, and that of nonwater supply side was gathered in 0~40cm soil depth for FI coupled with FN when nitrogen and water were applied to different furrows. Compared with CI, AI reduced soil nitrate nitrogen under the plant in 40~80cm soil depth by 9.9%~14.4% for different nitrogen supply methods. Compared with the other treatments, AI coupled with CN or AN maintained soil nitrate nitrogen in 0~40cm soil depth for a longer time during maize growth. Soil residual nitrate nitrogen in 0~100cm soil depth at harvest was comparable between AI coupled with CN and AI coupled with AN, and the residual of them was reduced by 11.7%~27.3% compared with those of the other treatments. Therefore, alternate furrow irrigation coupled with conventional or alternate nitrogen supply brought a relatively reasonable spatial-temporal distribution of soil nitrate nitrogen during maize growth, and lowered soil residual nitrate nitrogen at harvest.

Abstract:Anaerobic digestate of pig manure has the characteristics of continuous and quantitative poly. The effluent of anaerobic digestate contains a large amount of ammonia nitrogen. The processing capacity of the two stage air-recirculation stripping process is difficult to meet industrial requirements for treatment of anaerobic digestate of pig manure. Gas flow rate, liquid flow rate and gas-liquid ratio were chosen as running parameters of continuous air-recirculation process. The running parameters were studied and the process was optimized by response surface methodology. The initial ammonia nitrogen concentration of anaerobic digestate was (1444±37)mg/L. Ammonia nitrogen removal rate could reach (66.81±0.24)% when the gas flow rate, liquid flow rate and gas-liquid ratio were 530L/h, 445 mL/h and 2036, respectively, which was the best optimal parameters combination. The model optimized by response surface methodology could well analyze and predict ammonia nitrogen removal efficiency of continuous air-recirculation process for treating anaerobic digestate of pig manure. Gas-liquid ratio was the limiting factor for the process of continuous air-recirculation stripping process. According to perturbation plots of ammonia removal efficiency, the influence order from large to small of the three selected parameters for removal ability of ammonia nitrogen was gas-liquid ratio, liquid flow rate and gas flow rate. The process could be used to strip and recover ammonia nitrogen from anaerobic digestate of pig manure. It could reduce foaming tendency of treated fluid and the foams could be broken more quickly than the two stage air-recirculation stripping process. The process could reduce the height of stripping tower and investment of engineering. The result can provide some references for the continuous processing for anaerobic digestate of pig manure.

Abstract:Simultaneous nitrogen and phosphorus removal performance of a kind of biomembrane process integrated with partial circulatory aeration and two-stage treated water returning alternately was studied by utilizing the technology to treat typical decentralized wastewater from Modern Agricultural Science and Technology Innovation Base in Tianjin. The system with a total effective volume of 234m3 was composed of collecting tank, hydrolysis acidification balance tank, partial aerobic tank, secondary sedimentation tank and circulation tank. Sewage pumps in collecting tank were controlled by PLC automatic control system. Sludge pumps in secondary sedimentation tank worked 10min every 2h controlled by PLC automatic control system. Circulating water pumps in circulation tank controlled by PLC automatic control system could maintain necessary water flowing when inflowing and sludge returning were simultaneously stopped. The nominal air delivery of clover roots blowers in equipment room was 2.0m3/h. Hydrolysis acidification balance tank and partial aerobic tank were both filled with combined biocarrier at a filling height of 2m and the filling percentage and hydraulic load of the two tanks were 60%, 1.25m3/(m3·d) and 70%, 20m3/(m3·d), respectively. The operation of the whole system was controlled by PLC. Pumps for inflow worked intermittently and total time of it’s working was 6h every day. Aeration was continuous and partial. Since June, 2013, the test running was completed, the system was always operating formally in the way of intermittent inflow, partial aeration and alternate wastewate return. The raw decentralized wastewater was discharged from office buiding, research activities building, expert floor, restaurant, guest house and industry incubator and except for those from restaurants and toilets, which were firstly discharged into oil separation tank and septic tank for pretreating, the most was discharged directly into the system to treat. The designed treating capacity of this system was 150m3/d and the maximum influent quantity, minimum influent quantity and average influent quantity in reality was 140m3/d, 80m3/d and 100m3/d, respectively. The return ratio was controlled at 2∶1 by PLC. Through long tem operation of two years, the results showed that the average removal percentages for BOD5, NH3-N, TN and TP were 71.6%, 64.4%, 45.5% and 72.0%, respectively, and the average effluent concentrations of BOD5, NH3-N, TN and TP were 15.3mg/L, 9.2mg/L, 17.2mg/L and 0.8mg/L,respectively. It was indicated that the quality of treated effluent was up to “Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant” level 1B and treated water can be used as irrigation water. Nitrogen and phosphorus removal function was also well established when treating decentralized wastewater with high fluctuation and high loading. And it was further observed that removal percentages for BOD5, NH3-N and TP were increased with the increase of BOD5/TN and removal percentage for TN was decreased with the increase of BOD5/TN and BOD5/TP, while TN/TP was not one of main contributors to affecting removal percentage of BOD5, NH3-N, TN and TP.

Abstract:Composting treatment is a key method of processing organic solid waste, especially for agricultural organic solid waste. Aiming to study the feasibility of several selected variables from near infrared spectroscopy to quantify humic acid in compost, determine composting fermentation and develop corresponding control equipment to provide theoretical basis by near-infrared diffuse reflection spectrum. Totally 100 composting samples were collected, including 58 samples for calibration and 42 samples for validation. On the one hand, the humic acid of these samples were analyzed by using the International Humic Substances Society standard of humic acid method, on the other hand，those were scanned to obtain near infrared spectra with the wavelength range of 4000~9000cm-1. Both of spectroscopic pre-treatment method and sensitive variables were optimized, and then the model was built by partial least squares regression method．The results indicated that humic acid in compost can be determined by near-infrared(NIR) spectral technique, because they were combined with organic groups with NIR absorption. A method for the determination of humic acid in compost samples was established based on the combination of discrete wavelet transform (DWT) and NIR technique. In the proposed method, the raw NIR data and their wavelet coefficients were used for modeling and prediction of the contents of humic acid in compost by partial least square method (PLS). The model based on wavelet coefficients was better than that based on the full NIR spectral range. With the improved method, accurate prediction can be achieved. 

Abstract:The Fe, Co and Cu modified HZSM-5 zeolites were prepared via impregnation method and the modified catalysts were characterized by XRD, Py-IR and BET methods. Then online catalytic upgrading of rape straw pyrolysis vapors was performed over the modified catalysts to investigate their catalytic upgrading performance and anti coking performance. The results showed that loadings of Fe, Co and Cu were well-distributed, the acid distributions on the HZSM-5 were influenced differently by Fe, Co and Cu, and the channels were modified with the decrease of pore volume. The bio-oil yields were decreased with the increase of physicochemical properties after upgrading by employing the modified HZSM-5. The yield, oxygen content, pH value, dynamic viscosity and high heating value (HHV) of biooil obtained by using Fe, Co and Cu/HZSM-5 were 18.37%~19.03%, 15.13%~17.23%, 5.05~5.12, 5.16~5.22mm2/s and 34.56~36.01 MJ/kg, respectively. The refined bio-oil was composed of a variety of organic compounds which was indicated by many kinds of chemical functional groups, the content of hydrocarbons in refined bio-oil was increased significantly. Aromatization performances of Fe/HZSM-5, Co/HZSM-5 and Zn/HZSM-5 were improved and contents of the polycyclic aromatic hydrocarbons (PAHs) were obviously increased. And after catalytic upgrading by Fe/HZSM-5 and Co/HZSM-5, the contents of the monocyclic aromatic hydrocarbons (MAHs) were relatively high. Resistance performances of Fe/HZSM-5 and Co/HZSM-5 for amorphous coke were relatively strong, while that of Co/HZSM-5 for graphite coke was enhanced obviously.

Abstract:Time temperature indicator (TTI) is an intelligent tool to monitor and record directly the time-temperature history of cold chain and indicate quality of corresponding agriculture produce. Because of the restriction of classic matching condition, TTI has not been widely used in a wide variety of agricultural produces. Even when the TTI satisfies the conditions, the reliability of application is significantly affected by the unstable primary quality of agricultural produces. The application of TTI is expanded through adjusting its parameters, and determining the requirements for matching with agricultural produces and the calibration procedure of TTI. The result deduced through the reaction kinetics equations and contour diagram indicated that the only matching condition was activation energy of TTI should equal to the parameter of agricultural produce, or there existed a proportional relationship between the contour lines of the two products. Besides, an adjusting process of TTI should be used with the new matching condition together. Considering a change of the state of TTI and agricultural produces, the calibration process was divided into two parts: first was the static model with the two produces’ state which were static, and the second was the dynamic model with both of the two produces were in constant change. It provided corresponding theory and methods by using the Arrhenius equations and contour diagram for the two calibration process respectively. These calibration methods can expand the application of TTI and improve the precision and reliability of monitoring the quality of agricultural produces. Finally, the validity and reliability of the calibration theory were illustrated with an example by using two types of enzymatic TTIs, two types of chemical TTIs and Muscat grape.

Abstract:In addition to application in chemical manufacturing processes, epoxyethane is widely used in processes of food fumigating sterilization, particularly of grains and dried fruits. During the last decades, many research works have been focused on epoxidation reactions of ethylene by supported catalysts such as transition metal complexes and metal nanoparticles. In contrast with chemical synthetic methods, the biocatalytic reaction appears to be a mild and simple method. One biocatalytic method for producing epoxyethane is using methane monooxygenase (MMO) to insert oxygen across the carbon double bonds of ethylene. Epoxyethane synthesis by Methylosinus trichosporium IMV 3011 whole cells which contains the MMO has significant application potential as it is performed at normal temperature and pressure and causes no pollution. The process for producing epoxyethane was described. The effect of initial ethylene concentration on production of epoxyethane was studied. Initial concentrations of oxygen, ethylene and nitrogen were 50%, 20% and 30%, respectively. The amount of epoxyethane formed by free biocatalyst was 29μmol/mg in approximately 6h. Moreover, the amount of epoxyethane formed by immobilized biocatalyst was 34μmol/mg in approximately 8h. In a batch reaction system, the regenerated immobilized biocatalyst can be repeatedly used for 8 times and 89% of initial MMO activity was retained, and the amount of epoxyethane formed was 3.4nmol.

Abstract:Enzyme-assisted aqueous extraction processing (EAEP) has long been considered as a promising alternative to traditional solvent oil extraction, which has gained increasing attention recently. After EAEP of soybeans, three distinct layers are formed: cream, skim and residual fraction. The skim fraction contains substantial amount of protein as well as oil, sugar and other impurities. In order to recover value from this liquid fraction, ultrafiltration was employed for protein concentration and isolation. To investigate the interrelationship between operating parameters and membrane flux, Box-Behnken response surface methodology was introduced. The results indicated that the three factors’ effects on membrane flux followed the decreasing order as: solution mass fraction, transmembrane pressure and solution pH value. The improved regression model was fitted with determination coefficient of 0.9975 and optimal factors were as follows: operative pressure of 0.20MPa, solution mass fraction of 5.60%, and solution pH value of 8.50. The permeate flux under above conditions was 7.02L/(m2·h) and protein purity was increased to 88.63%. The infrared spectrum and HPLC analysis showed evidently characteristic peaks of functional groups in soybean protein and remarkable low levels of undigestible oligosaccharides. Besides, the protein extracted from EAEP showed improved solubilities especially at acidic pH value, but it slightly decreased emulsifying activity index and emulsifying stability index. Further improvement can be achieved if industrial fractionation unit was employed and process optimization was conducted. A complete costeffectiveness analysis would also need to be done to estimate the economic viability of this application.

Abstract:In order to investigate the influence of inulin on water migration in wheat dough, the freezable water (loosely bound water and free water) and nonfreezable water (tightly bound water) of wheat dough with different addition proportions (0, 2.5%, 5.0%, 7.5% and 10.0%) of short-chain, natural and long-chain inulin were determined by using differential scanning calorimetric (DSC) and nuclear magnetic resonance (NMR) techniques. The results of DSC showed that inulin with different degrees of polymerization (DP) all decreased freezable water content and increased non-freezable water content. And the effect of long-chain inulin on freezable water content was the most obvious. NMR results showed that with the increase of three kinds of inulin added, the contents of tightly bound water and free water were all increased in the dough, while the loosely bound water content was reduced, suggesting that the addition of three types of inulin all promoted the interaction between protein and water and inhibited the interaction between starch and moisture. The short-chain inulin and natural inulin had more obvious impact on the content of free water of the dough. On the other hand, the long-chain inulin had more significant influence on the content of tightly bound water; three kinds of inulin all had obvious effect on the loosely bound water content. In addition, the results of water state in the dough measured by DSC and NMR were consistent; there was a significant correlation between water migration and inulin addition. The test could provide data references for studying water distribution during the making process of dough and adjusting the product processing technology.

Abstract:In order to remove the deposited particles inside diesel particulate filter (DPF) and realize the DPF regeneration, fuel borne catalyst (FBC) additive is thought to promote diesel particle combustion with the active metal component in fuel. FBC can reduce the particulate ignition temperature, and also decrease the peak temperature of regeneration process. Naphthenic acid cerium solution was selected as FBC, which was blended with diesel by the ratios of 50mg/kg, 100mg/kg, 150mg/kg and 300mg/kg (Ce mass fraction) and marked as F50, F100, F150 and F300, respectively. The particulate physicochemical properties of a common rail engine fueled with Ce-based FBC were studied by using thermosgravimetric analysis, gas chromatography/mass spectrometry (GC-MS), scanning electron microscopy (SEM) and staged sampling particulate system methods. The variations of oxidation susceptibility，soluble organic fraction (SOF) components, size distribution and microstructure of particulate with and without FBC were studied. Results showed that the oxidation reaction of particulate matter (PM) was moved to the low temperature area with the increase of FBC ratio, and the mass fraction of 150mg/kg for Ce was the optimal blending ratio. The ignition temperatures of PM combustion were reduced by 94℃, 131℃, 150℃ and 152℃, and the peak temperatures were reduced by 61℃, 123℃, 146℃ and 161℃ with the four FBC fuels. Before and after adding FBC, the mass fraction of SOF in PM sample were 29.6% and 24.1%, respectively. Compared with pure diesel PM sample, the high number of carbon atoms in SOF was decreased, and the polycyclic aromatic hydrocarbons (PAHs) were decreased by 49.2%. For FBC particle sample the particle sizes were moved towards small size direction, the peak number concentration of accumulation modal particle was decreased by 14.4%, the peak number concentration of nuclear modal particle was increased by 8.9%, and the peak mass concentration was decreased by 14.5%. FBC particle sample, which had porous sponge morphology and low bonding degree, contained 1.23% of Ce element.

Abstract:For hybrid electric vehicles with traction motors installed behind transmission, traction motors can compensate the torque interrupt during gear shifting. Thus engine speed is adjusted to achieve the speed synchronization with AMT so that shifting smoothness is guaranteed without disengaging clutch. Quantitative feedback theory (QFT) combined with Smith predictor (SP) was adopted to achieve engine speed control. Firstly, a high realistic model of naturally aspirated gasoline engine was established in AMESim and the speed characteristic was validated to guarantee the reasonable features. Secondly, the engine nonlinear model was identified under piecewise working conditions so that several linear models with regions of parametric uncertainty were achieved. Thirdly, an optimized Smith predictor model was selected based on two criteria in frequency domain so as to deal with the intaketotorque uncertain time delay. Finally, based on quantitative feedback theory, an engine speed SP-QFT robust controller was designed to guarantee the robust stability and reference tracking. The simulation results showed that the step responses between the minimum and maximum speeds were of 0.75% overshoot, 0.7s settling time and 6r/min steady state error which met the demands of performance requirements of the synchronizer engagement during gear shifting of AMT and obviously improved the system dynamic characteristics compared with QFT controller and PID controller. Moreover, the simple form of SP-QFT controller is convenient to implement in engineering.

Abstract:A static outputfeedback based finite frequency H∞ controller design method was proposed for vehicle active suspension systems. The static output-feedback controller gain matrix was directly derived via a single-step linear matrix inequality (LMI) optimization. As the previous finite frequency H∞ control theorem did not satisfy the sufficient conditions of single-step method and contained some bilinear terms. The static outputfeedback control problem of previous finite frequency H∞ control theorem was infeasible. A new static outputfeedback based finite frequency H∞ control theorem was given by using the generalized Kalman-Yakubovich-Popov (GKYP) lemma. The initial static output-feedback controller gain matrix can be directly solved by a single-step LMI optimization. Compared with the traditional iterative linear matrix inequality (ILMI) and cone complementarity linearization (CCL) algorithms, the design process was greatly simplified. The initial infeasibility issue of the static output-feedback control was resolved by using the state-feedback information. Finally, the effectiveness of the proposed method was validated by numerical and experimental results. The results for different road excitations showed that the finite frequency controlling can improve ride comfort effectively, while keeping suspension dynamic deflection, tire dynamic load and controlling input within allowable values.

Abstract:Aiming to improve the convergence and diversity of multiobjective evolutionary algorithms (MOEAs) for solving complicated high dimensional multi-objective optimization problems, a multi-objective evolutionary algorithm based on orthogonal designing model (MOEA/D-OD) was proposed. Under the framework of multi-objective evolutionary algorithm with decomposition scheme as typical characteristics, the orthogonal designing model (ODM) was incorporated into decomposition mechanism. By utilizing ODM, the good genes carried by the recombinant parents were obtained by offspring to avoid blindness of searching to improve the convergence of the proposed algorithm. The decomposition mechanism was applied to selection to balance exploitation and exploration. MOEA/D-OD was compared with four stateoftheart MOEAs on 18 benchmark testing problems. Experimental results indicated that MOEA/D-OD can obtain good convergence while having uniform distribution and wild coverage for Pareto sets. The searching performance can stay well when solving complex problems with complicated PS. To validate its performance on constraint multiobjective optimization problems, the proposed MOEA/D-OD was applied to solve the I-beam with two conflict objectives. Compared with other algorithms, the uniformly distributed Pareto sets obtained by MOEA/D-OD showed its practicability for engineering problems, which was an effective approach for solving high dimensional and complicated multi-objective optimization problems. 

Abstract:Agricultural machinery professional chassis has many types of parameters and their difference between each other is so large that they cannot be fully compensated without any price. For these characteristics, the classical nearest neighbor algorithm which relies on weight properties in case-based reasoning is unacceptable in practice. Aiming at the situation above, the sorted method ELECTRE, belonging to multiple attribute decision, which was characterized by outranking relationship, was applied to the similarity assessment. In this algorithm, the first step was data preprocessing; then AHP was adopted to determine attributes’ weights; after that harmony and disharmony thresholds were obtained by constantly experimenting adjustment; and then construction and mining of relationships were carried out; the ultimate goal was to accomplish similarity assessment between design case and database cases. After that, crawler of walking system and chassis prototype were used for verification of the algorithm. Compared with the nearest neighbor method, the algorithm not only returned the former models which had higher overall similarity, but also marked the key parameters that affected the order, allowing users to have more followup evaluation. To make the algorithm to be more practical, a prototype interface of CBR was developed and the input of critical parameters and output of results were demonstrated. The overall result was good.

Abstract:Considering the packaging requirements of different sizes of customized cartons, the design method of variable actuated layout for 5R parallel kinematic mechanism was proposed. The kinematic analysis of 5R parallel mechanism was carried out, and different workspace maps were drawn by geometric method. A method of searching the reachable workspace through tracing the motion trajectory was proposed. These provided the basis for configuration application of the carton packaging mechanism. The folding process of carton cover was analyzed, and the 5R mechanism of the two actuated motors with coincident joint was selected as finger prototype to fold the flap. The motion parameters of actuated motors were extracted through the motion simulation, the fitted analytic function was input into the control program of finger mechanism. The experimental results verified that the expected motion trajectory of carton flap and finger mechanism had good controllability. Thus a reconfigurable carton packaging machine was developed to demonstrate the ability to erect different sizes of the cartons, which was different from the production line. By means of restructuring module structure and reconfiguration control program, the end effector was flexibility and controllable. The device had the characteristics of small space occupation and flexible control. It would be helpful for the delivery staff to improve the working efficiency and reduce the workload.

Abstract:Aiming at the dynamical parameter identification for robot manipulator, the artificial bee colony algorithm for identification was proposed. Considering the friction characteristics that the friction model was unable to reappear the behavior of complex dynamic friction at low speeds, the nonlinear robot model contained the nonlinear friction model was deduced by introducing the nonlinear Daemi-Heimann model. Then, the five order Fourier series was designed as exciting trajectory to collect experimental data, which satisfied velocity and acceleration boundary conditions. With the artificial bee colony algorithm, the colony bee was employed as search unit to identify unknown parameters which included 15 minimum inertia parameters and 12 friction parameters in the model through exchanging the information and retaining the superior individual. Finally, the established model was validated and analyzed, and all the results demonstrated that the proposed identification algorithm can accurately identify the dynamical parameters, and it also had highspeed convergence, strong search capability and can achieve the accurate prediction of robot driving torque. Compared with the linear dynamic model, the established nonlinear dynamical model can effectively improve the condition of sudden change about friction torque at the moment of joints commutation and can well reflect the dynamical characteristics of robot.

Abstract:With the widespread application of servo system in major equipment of industrial, military, aerospace and other important areas, there is a great demand for the electro-hydraulic servo flow valve which can response fast under the condition of high pressure and high flow. So the novel design project plan of 2D (two-dimensional) electro-hydraulic servo flow valve was made. The angular displacement of the proportional rotary electromagnet was detected by HALL sensor in this project, and compared with the input control signal to realize closed-feedback of angular displacements signal. Variable transmission ratio lever-fork structure was adopted. In order to enhance the valves control precision and anti-pollution capability, the rotary electromagnet angular displacement was proportionally converted into spool axial displacement by 2D technology which realized a closedfeedback of the chute sensitive channel. The mathematical model of the valve was established, and the simulation analysis was carried out on the whole system. Based on the analysis of the valves mathematical model and system parameters, sample equipment was manufactured and the experimental study was carried out. When the system pressure was 35MPa and the spool displacement was 0.8mm, the valve’s bandwidth was about 120Hz, dynamic response time was about 5ms, and the flow rate of 6mm spool diameter was 60L/min. The valve had a small and simple bodies, its weight was only one third of the same level valves. It also had low power consumption, and easy to realize closed-loop control, its static and dynamic performance was superior; therefore, the research result showed that it worked very well for airborne hydraulic system.

Abstract:A piezoelectric plate array energy harvester was proposed, which was excited by constant mass compressed gas, and the alternate high air pressure can be recovered. The structure of the system and working principle of the presented harvester were introduced, and the theoretical and experiment were analyzed. The theoretical analysis results showed that the piezoelectric plate had high bearing capacity and it can collect the compressed gas energy effectively. The piezoelectric harvester was subjected by various parameters such as compression volume and compression speed. The expected effect can be adjusted by changing different parameters. The diameter and thickness of piezoelectric unimorph were 12mm and 0.2mm, respectively. The diameter and distance of cylinder were 63mm and 150mm and the prototype were fabricated. The test system was built to research the rules and performances of piezoelectric array energy harvester. In the test, the pressure, cycle and flow were adjusted. Experimental results showed that the output voltage was simultaneously increased with the increase of flow when the pressure was fixed. With the increase of parallel number of piezoelectric plates, the output power was increased either. It had optimal effect when the five piezoelectric plates were parallel connected. The optimal load resistance was 3MΩand instantaneous power was 6.53μW under the five piezoelectric plates parallel.