Abstract:In order to solve the problem of low picking efficiency of harvesting robot under the target fruit oscillation condition, a recognition and location method of oscillating fruit based on monocular vision and ultrasonic testing was proposed. Firstly, the acquired sequential images of oscillating fruit were segmented by using Otsu algorithm based on R-G color component; morphological operation was employed to eliminate residual noise; and the region of target fruit was separated from backgrounds. Secondly, the region of target fruit was filled with gray threshold. Thirdly, the processed sequential images were superimposed and a composite image was obtained, and the 2-D centroid coordinates of the oscillating fruit were extracted from the fruit oscillating region in the composite image. Fourthly, the picking manipulator was controlled to move and its end was pointed to 2-D centroid coordinates, at the same time, the depth information of the target fruit was acquired through ultrasonic testing, and the peak-to-peak value of ultrasonic echo signal was extracted for recognition of fruit and tree. Finally, the end-effector of picking manipulator was started to grab the fruit when it was within valid range and the manipulator was stopped motion. The experiments results showed that the success rate of picking can reach 86%. This method is universal and suitable for apple, citrus, pears and other spherical fruits. The research can provide a reference for realization of harvesting robot practicability.

Abstract:Due to complex and changeful environment, the image segmentation of fruits with diseases in natural scenes is a difficult problem. A logarithmic similarity constraint Otsu and level set active contour (LSAC) based image segmentation approach of fruits with diseases was proposed in this paper. Considering the complexity and changeableness in natural scenes, the constraint Otsu method for segmenting logarithmic similarity image between diseased fruits and samples was introduced to distinguish diseased fruits and background; because of the local optimality of LSAC, improved distance regularization level set evolution (DRLSE) with adaptive expansion coefficient was used to lead contour to actual position. Firstly, the sample color of fruits with diseases, which included not only health area but also diseases area, was modeled using Gaussian mixture model (GMM), and then the logarithmic similarity between the image of fruits with diseases and model was obtained. Secondly, logarithmic similarity image was segmented with constraint Otsu and then morphology operator was used to filter out noise and interference. Thirdly, leastsquares ellipse fitting method was employed to further removal interference and get initial contour for LSAC. Finally, the contour of fruits with diseases was evolved to the actual position taking use of improved DRLSE with adaptive expansion coefficient. The experimental results show that the actual contour of fruits with disease in complex natural scenes can be obtained and the proposed method can provide the basis for the subsequent diseases density estimation and prevention of fruit diseases.

Abstract:In order to provide useful information for grasping of agricultural robot via perceiving surface roughness of fruits and vegetables, we designed and produced a PVDF tactile sensor, perceiving surface roughness via processing of tactile signal. With the mechanical analysis by ANSYS, we could determine the effective area and the reasonable location of sensor model. Four PVDF piezoelectric films and the resistance strain chips were randomly arranged in the model of fingers. The random distribution of the sensor elements would make tactile sensor as much as possible to obtain a wealth of information about the work environment. We built up a platform of tactile information detection to process data collection from three different roughnesses of fruits through multi channels data acquisition program. After extracting the sample characteristics, the maximum value, the minimum value and the difference between the maximum and minimum values of the signal were calculated as the tactile sensor characteristics. The differences between the maximum value and the minimum value of the signal were used as the pressure sensor characteristics. Then the SVR algorithm model was established to test the surface roughness of the fruits and vegetables. Experimental results were consistent with the actual setting of roughness class, which proved that the tactile sensor can detect surface roughness characteristics of fruits and vegetables.

Abstract:Global navigation satellite system for localization of agricultural machineries has been successfully used for many years in a broadacre environment. However, it will fail to work in a close planting orchard because navigation satellite signals are often interfered by dense tree canopies. Moreover, localization by only odometers can lead to a large accumulated error. Therefore, firstly the position of an agricultural robot before entering interrow of the close planting orchard was taken as an original point and a world coordinate system was established. A laser radar was applied to scan trunks on the both sides of the robot and the center points of trunks were extracted through circular clustering. The position values of these center points were saved in the world coordinate system. Then during the moving of the robot, the center points of trunks detected by the laser radar in real time were matched with those which had been saved previously in the world coordinate system. Matching results were applied to correct the robot position and heading angle which had been measured with only odometers. In this way the agriculture robot was able to locate itself accurately in the interrow of the close planting orchard. Repeated experimental results showed that the robot localization standard errors in both x and y directions in the world coordinate system were about 0.08m. The localization accuracy can meet requirements when the agricultural robot is applied in the close planting orchard. Moreover, the successful interrow localization is the premise of global positioning and navigation of the robot working in the orchard.

Abstract:To achieve super rice seeding according to the numbers of seeds per bunch, it requires precise detect the seeding quantity per bunch in the potted seeding tray. The traditional detection method based on the area and average gray has low detection precision, which could not accurately identify the number of seeds per bunch and reduce adult seedling rate. There is a close relationship between the shape features of seeds in single connected region and the seeding quantity. In this article，a method base on the improved shape factor was presented to detect the seeding quantity per bunch in the potted seedling tray. Firstly，the RGB weighting method was used to gray the color image, the Otsu algorithm was used to binary image processing，morphological filtering algorithm was used to remove the image noise. Secondly, the small image of seeds per punch in potted seedling tray was extracted by the masked locationbased technology and the single connected region on the small image was detected. Thirdly，the shape features of each seed were extracted，such as the area and perimeter of single connected region and area of the minimum enclosing circumscribing convex polygon. Then，the improved shape factor was computed according to shape features of each seed. Lastly, the improved shape factor and the area of single connected region were used to classify seed connected regions into cavity (including impurities), one particle, two particles, three particles, or four particles and above. After adding up the particles of each bunch, the seedling tray seeding quantity can be obtained. The result showed that the detection accuracy of the number of seeds between zero particle and three particles in every single connected region was up to 95% and the detection accuracy of the number of seeds more than four particles in every single connected region was up to 90%. The detection accuracy of the number of seeds in every bunch was up to 93%. Each image was processed less than 0.518 seconds. It’s proved that the method of potted seedlings tray sowing quantity detection meets the requirement of automated rice sowing test line. The research result can provide reference for the follow-up work of reseed.

Abstract:According to back-to-back traversal of plant protection UAV, a kind of working area decomposing method based on grid method was used to extract the UAV working path. A route planning algorithm with the minimum return number was proposed in order to reduce the ineffective energy consumption in non-operate situation. The spraying amount and return points of the sorties were reasonably allocated to improve operational efficiency. The simulation results show that using this algorithm in an area of 15600m2, compared to the return route in the liquid exhaustion situation, energy consumption of the UAV was reduced by 5.99%; while in an area of 42000m2, energy consumption of the UAV was even reduced by 12.89%. When the operation area was larger, the energysaving effect was more obvious, which proved the feasibility of route planning algorithm. Field tests in an area of 2500m2 proved that there were deviations between theory and practical routes. The possible reasons were GPS positioning error, wind and center of gravity in liquid. So the GPS positioning accuracy needs to be improved, and the flight control system needs to be further improved. This flight route planning algorithm was proposed for automatic UAVs in unmanned operation, thus the flight routes were set before operation, and the energy consumption of UAVs and flight sorties can be estimated in advance. Nowadays, the unmanned operation becomes a new trend, and this flight route planning algorithm can be widely used in precision agriculture.

Abstract:In order to discuss the feasibility of longitudinal seedling feeding mechanism for rice pot seedling transplanting with ratchet gear, the working principle of longitudinal seedling feeding mechanism and the transmission characteristics of ratchet gear mechanism were analyzed. Considering that the pot seedling feeding mechanism of high-speed rotary pot seedling transplanting machine must meet the requirements of steady transmission, accurate transmission ratio, good working reliability, no accumulated error in operation as well as low vibration and noise, the longitudinal seedling feeding mechanism for rice pot seedling transplanting with ratchet gear was designed. The mathematical models of some important geometrical parameters in the design of structure were built and then these parameters were optimized. Besides, the virtual model was also built by using CAD/CAE software. At last, the bench test was carried out. The test result showed that the proposed longitudinal seedling feeding mechanism could meet the working demands of highspeed rotary pot seedling transplanting machine, which provides theory and implement basis for developing this kind of transplanting mechanism.

Abstract:In order to overcome the shortages of complex structure and too much parameters of double five-bar transplanting which are difficult to be solved by traditional analytical method, the working principle and kinematics model of rape pot seedling were analyzed. Also a multi-objective optimization design model was established. The calculation and parameter analysis were carried out with Matlab software. And the kinematics characteristics of double five-bar transplanting mechanism were analyzed, which matched with the solving results of the multi-objective optimization design model. The consistency verification experiment was carried out by high speed photography system. The result showed that both of transplanting spacing and locus height of the rape pot seedling transplanter were 300mm, with the forward speed of 0.3m/s and transplanting frequency of 60 seedlings per minute. The displacement between buried locus and unearthed locus was less than 0.91mm with the transplanting depth within the range of 60~100mm, which revealed the good verticality and coincidence between them. The horizontal velocity of duckbill-type planting unit was 0.04m/s at the lowest point of the transplanting locus, and the swinging angle was in the range of -2.3°~ 2.3° at planting stage, which were benefit for planting. In falling stage, the swinging angle of duckbill-type planting unit was in the range of -2.4°~2.2° and the vertical velocity was less than 0.7m/s, so that the vertical displacement was too small to catch the seedling for duckbill-type planting unit. The demands of rapeseed mechanized transplanting could be met with proposed method.

Abstract:In the process of rice growth, the weeds will decrease the quality and yield of rice. At present, both herbicide and manual weed control have many shortages. Chemical weed control causes environmental pollution, reduces crop nutrition and increases weed drug resistance. Manual weed control is laborintensive, lowefficient and bounds labor. Mechanical weed control is helpful to protect environment and the high efficient will be an irresistible trend. In order to improve the weeding rate and reduce the damage rate of rice seedlings while weeding, the mechanism analysis and improvement of paddy field weeding device was were done. The weeding device was symmetrically installed on the two groups of spring tooth disc (left and right). The two groups of spring tooth disc rotated to complete the weeding by flexible shaft. According to kinematics analysis of the key components of spring tooth disc and the strength analysis of rice seedlings and barnyard grass, the kinematics model of spring tooth disc and stress model of paddy rice seedlings and barnyard grass were established. According to the stress analysis, the strength condition of rice seedlings and barnyard grass were presented. According to physical characteristics of rice seedlings and barnyard grass and the basic parameters of spring tooth disc, the variation range of rotating angular velocity and teeth number of spring tooth disc were obtained. Through various testing on the compaction device, the optimum working parameters of the compaction device were obtained. The test showed that rotating angular velocity was 25.1rad/s and teeth number was 5. Performance testing in field was carried out for the paddy weeding device. The results showed that weeding rate was 80% and injury rate was 4.5%. The weeding machine had good quality, and had met the agronomic technical requirements when rotating angular velocity was 25.1rad/s and teeth number was 5.

Abstract:In order to satisfy the performance requirements of spatial cam mechanism in rotary converter of liquid fertilizer applicator, such as stable working and precise liquid fertilization, a mathematical model of spatial cam was established. The software for optimizing the spatial cam was developed by using Visual Basic 6.0. The average radius of cylinder was got as 37mm and curve profile of spatial cam was obtained. Threedimensional model and kinematics simulation of spatial cam mechanism were established by using Pro/E software, which verified the design reasonability of spatial cam mechanism. Finally, the mechanism was tested on the testbed. The result showed that when the pump pressure is 0.4MPa and the output shaft speed is 69.75r/min, the fertilizer consumptions are almost the same at different measurement time, and the picking hole mechanism only sprays liquid fertilizer on the rise to fall travel process of converters spatial cam. The results show that the proposed spatial cam mechanism could work smoothly that meets the design requirements of spatial cam. 

Abstract:Aiming at the existing problems of big hole and bad verticality of picking hole mechanism, a kind of picking hole mechanism of noncircular gear planetary system for deep liquid fertilizer was designed. To make picking hole mechanism satisfy the agronomic required verticality when it gets into and out of the soil, the reverse design and kinematics simulation analysis of picking hole mechanism of noncircular gear planetary system were presented based on Matlab GUI development platform. Through the finetuning of a small amount of date points on static trajectories which were generated in the inverse design and kinematics simulation, a set of optimal parameters were obtained. The picking hole mechanism model was established by applying Pro/E software. And with the ADAMS software, the trajectory curves were got. Finally, this picking hole mechanism was tested on the testbed, and the results showed that when the hole width was 30.3mm and the hole distance was 221.9mm, the proposed picking hole mechanism could meet the design requirement, that means, good verticality and small hole when it gets into and out of the soil.

Abstract:In order to optimize the integrated water and fertilizer fertigation machine and improve its fertigation performance, the working principle of Venturi injector was analyzed. According to the table of economic flow rate, the frictional loss and local loss of pipeline system as well as fertigation machine were taken into consideration. Taking flow of fertilizer absorption as evaluation index, single factor optimization experiment was carried out on some main parameters in Venturi injector which is the key component in the system by using CFD numerical calculation, including tapered angle α, divergent angle β and throat diameter d0. The influence rule of three parameters above on fertigation performance was obtained. Then through the orthogonal test with 3factors and 3levels, the combination of optimal structure parameters was got with CFD numerical calculation, that means, tapered angle α=20°, divergent angle β=8° and throat diameter d0=6mm. And the best fertigation performance was got when the angle between the absorption tube and the main pipe of Venturi was around 40°. Comparing with the simulated data and actual operation data of integrated water and fertilizer fertigation machine, it indicated that the fertigation absorption flow of Venturi was increased by about 38.6% after CFD numerical optimization, and the overall fertilizer absorption flow was increased by about 47.6% with fertigation machine matched with the fuzzy automatic control system. The energy saving effect is remarkable.

Abstract:In order to solve the problem of yield monitoring during peanut harvesting, aiming at 4HBLZ-2 type selfpropelled peanut combine harvester, an intelligent yield monitoring system was designed. Hardware part included Beidou satellite positioning system, the single chip microprocessor, weight sensor and German ACO contact online moisture sensor; it was connected to the host computer through CAN bus interface. Weighing controller adopted 24bit A/D converter with high precision and digital filter algorithm to ensure the accuracy of weighing data working under vibration environment in the field. Quantitative weighing and mesh subdivision technique were applied to harvester yield monitoring field in this system for the first time, compared with impactbased yield monitoring system, it could reduce more accumulative error caused by peanut harvester vibration working in the field. Software part adopted crossplatform application Qt to achieve the data realtime reception and storage of different sensors, then Beidou data and yield data were processed, and it adopted the way of accumulating different harvesting block yields to establish the mathematical model. The software could query yield data in arbitrary setting blocks, and also realize plane displaying and 3D stereoscopic gradient color displaying. In order to test the stability of yield monitoring system of peanut harvester under working state, yield monitoring system performed vibration test under five different conditions. The absolute relative error of yield was below 2% in condition No.4 in laboratory and below 5% in field.

Abstract:In order to further study the operational principle of all forms of peanut picker and picking component, explore the peanut pods damage mechanism, distribution regularity and peanut plant dynamics situation, and then optimize the structure and parameters of peanut picker, a multifunctional modular fullfeeding peanut picking testing device was designed. It mainly composed of frame, motor, transmission system, picking system, cleaning system, variable speed and control system as well as pod distribution test system. As a peanut picking testing device, it has the following functions: by changing and controlling the moving direction of the peanut plants, seven different kinds of feeding and picking program with tangential and axial cylinder could be achieved, which are tangential flow single cylinder, axial flow single cylinder, tangential flow doublecylinder, tangentialaxial flow doublecylinder, tangential flow doublecylinder, double tangentialhorizontal axial flow three cylinders and tangential double axial flow three cylinders. And the picking cylinders and the speed between them could be adjusted through the speed regulating of the inverter drive combined with mechanical transmission. In addition, the distribution of peanut pods in each picking mechanism would be studied with the divided material collection box. Besides, it showed that the device could be used to carry out the performance tests of picking with different picking parts and the combination of tangential and axial cylinders. And the main parameters were as follows, rotational speed of 200~800r/min, picking gap of 25~50mm, and the maximum feeding quality of 5kg/s.

Abstract:Crop model has been becoming a powerful tool for agricultural water and nitrogen management and implementation of watersaving irrigation. This study was to explore the accuracy of CERES-Maize model for its simulations of summer maize growth, development, yield, and soil moisture under different scenarios of water stress. Field experiments were conducted under a rainout shelter for summer maize growing under water stresses at different growth stages in two consecutive growth seasons (2013 and 2014). The whole growth season of maize was divided into four stages (seeding, jointing, tasseling, and grain filling). Water stress occurred at every single stage, while irrigations were applied at the other three stages. Thus, there were four different levels of water stress period (D1~D4). Two irrigation levels of 70mm (I1) and 110 mm (I2) were applied according to the average rainfall during growth season of summer maize in 56 years. Consequently, there were a total of 8 treatments, with 3 replicates for each. The plots followed a split-plot experiment design. An extra control treatment with irrigation at all four stages was arranged nearby. The experimental data were used to calibrate and validate the CERES-Maize model with two parameter estimation tools of GLUE (Generalized likelihood uncertainty estimation) and PEST (Parameter ESTimation). Additionally, an overall evaluation was made with cross validation method for the prediction accuracy of the CERES-Maize model. Results showed that both GLUE and PEST had good stability and convergence for the estimation of genetic parameters of CERESMaize model. The parameters values separately estimated with GLUE and PEST were very close. However, PEST had higher efficiency since it consumed much less time than the GLUE. CERES-Maize model can precisely simulate the growth, development, yield, and soil moisture of summer maize under full irrigation condition, since the absolute relative error (ARE) and relative root mean squared error (RRMSE) values of model calibration and verification were only between 6% and 8%. Anthesis and maturity dates of summer maize were different when water stresses occurred at different growth stages, but CERES-Maize model failed to simulate such kind of phenology differences caused by water stresses. In cross-validation, model simulation errors became bigger when water stresses occurred at early stages, especially at jointing stage. CERES-Maize model failed to correctly simulate the influences of water stresses at early growth stages on the final grain yield of summer maize, which was probably caused by the underestimation of LAI under such conditions. Lower estimated LAI values then made the simulations of ET incorrect. In general, CERES-Maize model was proved to be limited to simulate the growth, yield, and soil moisture of summer maize when under serious water stresses at early growth stages. It is necessary to modify accordingly the CERES-Maize model if it will be used in the simulation of agro-ecological systems of summer maize in arid and semi-arid areas of China.

Abstract:Leaf area index (LAI) is an important parameter for evaluating the growth status and yield prediction of winter wheat. Spectral reflectance of leaves and concurrent LAI parameters of samples in Tongzhou and Shunyi Districts, Beijing City, China, were acquired during 2008/2009 winter wheat growth season. The correlation coefficient (|r|) Akaike’s information criterion (AIC), grey relational analysis (GRA)AIC, variable importance for projection (VIP)AIC, VIPpredictive residual error sum of square (PRESS) were integrated with partial least squares regression for estimating LAI, and the estimation models of optimal LAI were presented by using AIC and compared with traditional PRESS function. The results indicated that the R2 of |r|-PLS-AIC, GRA-PLS-AIC, VIP-PLS-AIC and VIP-PLS-PRESS models were 0.72, 0.67, 0.73 and 0.70, respectively. The VIP-PLS-AIC had higher predictive ability for winter wheat LAI than VIP-PLS-PRESS. Considering time domain characteristics of LAI, the relevant data acquired in Tongzhou and Shunyi Districts, Beijing City, China, during 2009/2010 winter wheat growth seasons were used to validate the models in different years. The results showed that VIP-PLS-AIC with RMSE of 081 had higher predictive ability than |r|-PLS-AIC with RMSE of 0.87, GRA-PLS-AIC with RMSE of 0.96 and VIP-PLS-PRESS with RMSE of 0.83. The results indicated that AIC could not only obtain the estimation model of optimal LAI at the same year, but also could be applied to the LAI detection in different years.

Abstract:The Guanzhong Plain of Shaanxi Province is one of the major regions of wheat production in China. Farmers believe that the more nitrogen is applied, the higher yield is obtained. In fact, the excessive application of nitrogen fertilizer does not increase the yield of wheat synchronously, but cause a series of environmental issues. A simple but effective technique for crop nitrogen estimation can lower the production cost and improve the ecological environment. The critical nitrogen concentration can be used to diagnose the crop nitrogen status. Previous researchers mainly developed the critical nitrogen dilution curve based on the aboveground dry matter, whilst the leaf dry matter was used to establish the curve in this study. The field experiments were conducted between 2013 and 2015 to construct and validate the critical nitrogen dilution curve based on leaf dry matter in the vegetative stage in winter wheat. In this study, we selected six winter wheat varieties and set four nitrogen levels N0（0）,N1（105kg/hm2）,N2（210kg/hm2） and N3（315kg/hm2）. Results showed that there were negative power relationships between the critical nitrogen concentration and the maximum leaf dry matter. The nitrogen nutrition index derived from the critical nitrogen dilution curve could be used to evaluate the nitrogen nutrition status of winter wheat. The nitrogen nutrition index increased with the nitrogen rate, with the values between 0.57 and 1.21. The relation between nitrogen nutrition index and relative yield indicate that 105~210kg/hm2 was the optimal nitrogen rate for winter wheat in the Guanzhong Plain. The critical nitrogen dilution curves based on leaf dry matter were successfully used to assess of the nitrogen nutrition status of winter, which can be used for guiding scientific application and diagnose of nitrogen in Guanzhong Plain.

Abstract:The simulative crop coefficients in each growth period of winter wheat were calculated by the potential and actual evapotranspiration of winter wheat during the whole growth period that both simulated with crop growth model. These simulative crop coefficients were compared with the standard crop confidents at different growth stages provided by FAO and the comparison results verified the accuracy of their values and trends. The experience logarithmic model was built based on the leaf area index obtained by both point-based measurement and remote sensing inversion method. The continuous daily regional crop coefficient could be calculated by remotely sensed leaf area index. The ratio of simulated crop coefficient and daily regional crop coefficient could be used as an optimization factor for evapotranspiration model and the evapotranspiration results of simulative crop coefficient before and after optimization in the whole growth period during 2013—2014 in Guanzhong Plain were obtained. Compared with the point-based measured data, it was found that the maximum relative error was reduced to 9.89% from 14.36% after optimization. So the optimized evapotranspiration reversion model was more accurate than the model without optimization, especially under the condition of low plant coverage. The accuracy showed a significant improvement.

Abstract:Based on the experimental factors like soil moisture, air temperature, relative humidity and solar radiation, a composite quadratic orthogonal regressive rotation design of four factors and five levels was adopted to characterize the co-ordination of environmental factors in driving and regulating transpiration rate of greenhouse grown muskmelon. Soil moisture was maintained by using weighing method, and environmental factors were controlled by the chamber of a portable photosynthesis system (Li-6400; LI-COR). Transpiration rate and stomatal conductance were measured under different combinations of environmental factors. Characterizations of main effect, single effect and marginal effect for each environmental factor were determined by using the environmental data. The results showed that: all of the environmental factors were positively correlated with transpiration rate except relative humidity. Correlation between transpiration rate and soil moisture, temperature can be described in a linear function, respectively. But solar radiation and relative humidity exhibited parabolic functions with transpiration rate. Soil moisture and temperature showed a stable positive marginal effect on transpiration rate with increasing treatment levels, while solar radiation and relative humidity showed linear functions with a positive and negative slope, respectively. Marginal effects of solar radiation and relative humidity were divided into positive and negative with threshold treatment levels of -0.69 and -1.49. Considering the tight coordination between environmental factors in regulating transpiration rate, a quantitative framework was presented to characterize and quantify pathways of each environmental factor. Vapour pressure deficit (VPD) was an important intermediary factor in modulating driving force of other environment factors, which performed a dominant role in determining leaf transpiration rate at the instantaneous scale.

Abstract:In this paper, high voltage electrostatic field (HVEF) was applied to agricultural production. The experimental equipment of HVEF was designed. To explore the effect of HVEF on physiological characteristics and yield of hydroponic tomato, illustrate the influence mechanism of HVEF on the tomato seedlings, tomato seedlings were cultivated in greenhouse. The seedlings with two true leaves and the same height were transplanted to experimental lab and gone on the treatment of HVEF. The seedlings were cultivated in nutrient solution mode. Three different high voltage electrostatic fields of 2.00, 2.25, 2.50kV/cm were adjusted and the seedlings between the two parallel-electrode plates were treated under this condition for 8 h. After finishing the treatments of HVEF, some of the seedlings were continued to be cultured by using of inorganic matrix and nutrient solution culture in greenhouse. Then, the stem diameter, fresh weight, chlorophyll content and root morphological characteristics of tomato seedlings, as well as ultimate yield of tomato were studied. In addition, root activities and membrane permeability of other seedlings, and the changes of ion concentration of uptake solution as soon as HVEF treatment was finished, were analyzed. The results show that the high voltage electrostatic field, compared with the control (without electric field), changes the growth characteristics of tomato, and the electric field intensity of 2.25kV/cm increases stem diameter, fresh weight and chlorophyll content, and promotes the effect of the optimal root morphology. As a result, the yield is increased by 23% in contrast with the control.

Abstract:This study mainly assesses land use ecosystem service values in Beijing City during the year of 1993, 2001 and 2007. It calculated the gravity center changes of ecosystem service values based on the torque balance point method, and also analyzed the spatial and temporal variation of ecosystem service value distribution in Beijing City. The results indicate that: the ecosystem service value in Beijing City increases from 29.769 billion Yuan in 1993 to 29.905 billion Yuan in 2001, and then the value decreases to 29.212 billion Yuan in 2007. The transmission of gravity center in ecosystem service values is due to the changes of land use. The central values of cultivated land, grassland, wetland have moved from south to north during 1993—2007, which enhanced the change of the total value of gravity center. For instance, the gravities of park green land and forest were always changed from north to south. The changes of gravity for different functional values of ecosystem services illustrate that the gravity center values from waste material, climate regulation, gas regulation, food production, soul formation and conservation, and entertainment culture, move from south to north, and the gravity of raw materials is opposite. For biological diversity protection, the gravity center shifts from west to east. For water conservation, the center goes from north to south and then to north again during the threeyear period. The paper provides accurate information for municipal government decisionmaking, and formalises ecological and environmental protection related policies in Beijing City.

Abstract:In order to better understand the effects of tillage erosion on carbon cycle in the sloping farmland, responses of soil organic carbon and aggregate associated carbon to soil erosion were explored in a mountainous region of northern Sichuan Basin, southwest China, with 137Cs tracer and laboratory analysis method. The results showed soil loss was found in upslope where 137Cs concentrations were lower (soil erosion rates were greater), whereas soil deposit occurred in the bottom of sloping farmland where 137Cs concentrations were higher (soil erosion rates were less). Not only water erosion but also tillage erosion contributed to soil losses. Tillage erosion played an important role in sloping farmland soil redistribution, average tillage erosion rate in upslope was 63.22t/(hm2·a）, occupying 94.61% of total soil erosion. Soil deposit rate was 23.94t/(hm2·a）in low positions. Soil erosion resulted in the lowest ＞2000μm, 250～2000μm and 53～250μm size aggregates, and created the highest ＜53μm aggregate fraction in upslope. Meanwhile, soil organic carbon and aggregate associated carbon content and stock were significantly lower in upslope positions than these in bottom slope positions. There was significant correlation between soil organic carbon, content of aggregate associated carbon and 137Cs inventory, suggesting that soils were more fertile in bottom positions than in top positions due to soil redistribution by soil erosion. Therefore, fertilization management strategies should involve spatial variation of soil properties in purple soil of hilly sloping farmland.

Abstract:Due to the widely existence of soft rock and the exploitation of coal resource, serious ecological and environmental problems occurred in the contiguous areas of Shanxi, Shaanxi and Inner Mongolia in China. In order to restore regionally ecological environment, this study was conducted to improve sandy soil using soft rock in the energy communities, and realize the transformation of soft rock into available resources. Previous research found that soft rock could improve hydraulic properties of sandy soil. But there are few researches about the nutrient availability of soft rock distributed into sandy soil. Soft rock was mixed in sandy soil with seven ratios: 0，10%，25%，50%，75%，90% and 100%. Adsorption kinetic were determined and fitted with Freundlich，Langmuir，Temkin and DubininRadushkevich models. Adsorption isotherms were measured and modeled with Pseudofirstorder, Pseudosecondorder, Biconstant and Intraparticle diffusion models. This study was conducted to understand the effects of different additive proportions of soft rock amended sandy soils on the adsorption of NH+4 N, and to select the optimal adsorption model of improved soil. The results can be used to guide reasonable fertilization of nitrogenous and improve the utilization efficiency of fertilize. The results showed that: with the extension of reaction times and the increase of equilibrium concentration, the NH+4 N adsorption capacity was increased in improved soil. Reaching to the adsorption equilibrium, sandy soil needs 4 hours and soft rock needs 16 hours. Adsorption capacity of NH+4 N was the largest in sandy soil and the least in soft rock, the maximum adsorption of NH+4 N in soft rock was 20 times of sand soil. With the increase of the soft rock proportion in improved soil, NH+4 N optimal adsorption was increased linearly. Soft rock could improve the NH+4 N adsorption capacity of sandy soil. The pseudosecondorder kinetic model and the Freundlich isotherm model could well describe NH+4 N absorption in improved soil. NH+4 N adsorption is a spontaneous process and a favorable adsorption.

Abstract:The soil macropores development and distribution in the field play an key ecological role in soil ecosystems, because of the complex interaction of soil’s structures, moisture condition, stress level and biological activities. However, few researchers have used the ecological method to study the spatial structures of the soil macropores. This paper presents a new method (i.e., combining with the ecology and morphology) to quantitatively investigate the spatial structure characteristics of macropores in purple sandstone regions the typical three land use types in Three Gorges Reservoir Area, with the stand spatial structure analysis method and image processing technology. The results demonstrated that the shapes and spatial structures of the soil macropores of three land use types were highly complicated. The soil macropores were mainly represented a gradual tendency of clumped distribution pattern and community structures (i.e., composing of the same pore size macropore with increasing soil depth), especially the grassland. The development degree of macropores in three land use types gradually decreased with the increase of soil depth. Three land use types’ development degrees of the preferential flow were in this order from high to low: grassland, orchard and farmland. The spatial connectivity, the development degree and water conductivity of different preferential flow paths in same land use type were in this order from high to low: for grassland, \[5.0mm, ∞), \[2.5mm, 5.0mm), \[1.0mm, 2.5mm), (0, 1.0mm), however, for farmland and orchard, \[10mm, 2.5mm), \[2.5mm, 5.0mm), (0, 1.0mm), \[5.0mm, ∞). The analysis results of stand spatial structure analysis method were compared with distribution density of the soil macropore, variability, complexity and previous research methods. The same result proved the accuracy and applicability of stand spatial structure analysis method used to analyze the spatial structures of macropores. This new method provides an effective, convenient, rapid and more economical method for studying spatial structures of macropores, and gives us more spatial structure information from the viewpoint of ecology. Meanwhile, it compensates for the deficiency of the current methods （e.g., dye tracer, visual liquid latex, water breakthrough curves analysis and CT technique） based on physical and chemical analysis about theoretical analysis of macropores structures, and further reveals the reasons about the formation and distribution of spatial structure of the soil macropores.

Abstract:In drip irrigation design, calculation method of emitter local resistance coefficient is different with different arrangements and the local resistance interaction is existed under some conditions. Local resistance interaction of emitters was appeared when the emitter spacing was less than a critical value, at this time, the emitter local resistance was different from local resistance in independent emitters. Local resistance coefficient would be calculated separately with different methods and different emitter spacings.Based on this, water filling tests of 16 drip pipe with six kinds of emitters spacings were conducted to investigate the interaction of local resistance in trickle laterals of online emitters. Meanwhile, the CFD software was applied on numerical simulation and verification. On this basis, 20 drip pipeswere simulated. The results showed that the simulatedvalues were in agreement with the experimental values for local resistance interactive coefficient of emitters. The local resistance interactive coefficient reduced with the decreasing emitters spacing. The changes of disturbance range and velocity distribution near the emitters were the main reasons for local resistance interaction in trickle laterals. Local resistance interaction of emitters should be taken into account when the emitter spacing was less than 0.5m. In this case, the values of interactive coefficient were varied from 0.9 to 1.0.

Abstract:Glucose is one of main intermediate components and final aqueous product from biomass hydrothermal carbonization (HTC). To explore the effects of glucose on reaction processing and hydrochars formation, wheat straw was hydrothermally treated in different concentrations of glucose solution, and the process and products were analyzed. All the experiments were carried out in a 2L autoclave at temperature of 220℃ for residence time of 120min. The results show that with increasing concentration of glucose, the yields and carbon content of hydrochars increase slightly. However, the hydrogen and oxygen contents of hydrochars are not substantial. When the added glucose mass is 0.4 times as much as the wheat straw mass, the yield of hydrochars reaches 68.56%. Glucose could cause an increase of mass transfer resistance for sugar monomers produced from hemicelluloses and cellulose degradation to enter the liquid phase. The precipation of glucose could impede the degradation and carbonization reaction of biomass during the HTC process. Thus, the aromatic characteristic peaks of hydrochars in Fourier transform infrared (FTIR) spectra weaken, and the diffraction peak intensity of cellulose in Xray diffraction (XRD) spectra decreases. Moreover, the thermal stability of hydrochars also decreases. During reutilization of the HTC processing water, the dissolvable sugars could be extracted. 〖JP2〗When the wheat straw is cotreated with glucose under hydrothermal conditions, degradation of glucose is possible the main pathway. When compared with liquid products from the wheat straw HTC using pure water, the concentrations of furfural, 5hydroxymethylfurfural (5HMF) and acetic acid increase. The concentration of 5HMF increases to 20.21g/L when the ratio of glucose to wheat straw is 0.4.

Abstract:As a high value-added platform chemical in biorefinery, 5-hydroxymethylfurfural (HMF) can undergo conversion to various fine chemicals and high quality liquid fuels. Glucose decomposition in liquid-phase system is the conventional route for HMF production. To get insights into the effects of different solvents on HMF formation, the conversion of glucose in three different solvents, including water, dimethylsulfoxide (DMSO), and water-DMSO mixture, was performed over the temperature range of 100℃ to 200℃. The results showed that the yield of HMF in water-DMSO mixture at 175℃ was up to 20.7%, which was much higher than that in pure water (11.86%) and DMSO (10.0%). A reaction model involving the formation pathways of HMF, levulinic acid (LA) and humin was used to analyze the kinetics of glucose decomposition, and the obtained kinetic parameters predicted experimental results very well. It was found that DMSO altered the path of glucose isomerization, resulting in the formation of fructose and galactose. Compared with the enhancement of HMF activity in water, DMSO suppressed the further reaction of HMF to form LA and humin. Moreover, the properties of the humins generated in the three solvents were characterized, and the corresponding formation mechanisms were discussed.

Abstract:Experimental results are presented on the gasification of pine sawdust pellets using high temperature steam as the gasification agent. Downdraft gasifier was adopted as reactor, the reactor temperature was varied from 700℃ to 950℃, and steam to biomass ratio (S/B) was changed from 0.3 to 1.0. Based on biomass gasification technology, the gasification characteristics of pine sawdust pellets were deeply discussed. In addition, numerical computation using Gibbs free energy minimization was applied and compared with the experimental results. The results show that hydrogenrich gas could be effectively produced by high temperature steam in downdraft gasifier, and the carbon layer played an important role in preparation of hydrogenrich gas, in which steam reforming reaction and tar cracking were taken place. H2 and CO yields would rise at higher temperature, and H2 volume fraction would reach the peak when reactor temperature raised some value，H2 fraction would decline if the temperature was continued to raise. The increase of S/B could develop H2 content of product gas, temperature of material bed would be dropped by some endothermic reactions, and the increase of H2 volume fraction was restrained. In the test, the peak value of H2 volume fraction was 47.67% with S/B of 1.0 and temperature of 900℃. These results also provide the operating law for downdraft gasifier with high temperature steam.

Abstract:The aim of this study was to investigate the effect of micronization on the physicochemical properties of corn stover. With the decrease of powders in four different particle sizes, the bulk density changed from 0.11g/mL to 0.41g/mL, the surface area increased to 1.05m2/g, and the angle of repose and slide of corn straw powder increased to varied degrees. Changes of the microstructure and physicochemical characteristics of different powders were assessed by using scanning electron microscopy and X-ray diffractometry. Compared to general powders, with the agglomerates in ultrafine grinding powder and increased size distributions, the ultrafine grinding reduced the particle size and crystallinity of the wheat straw significantly, that means the ultrafine powder diameter was reduced to 15.54μm, and the crystallinity was reduced from 44.72% to 13.68%. Both of the microwave-assisted and general oil bath heating were carried out in alcolhol liquefaction. With the microwave heating, the liquefied yield of ultrafine powder was 90.37% within 5min, however it needed around 1h with oil bath heating, which indicated the effectivity of microwaves. With the general oil bath heating, the liquefied yield of ultrafine powder was 95.30% with in 120min, which was higher than that of common powder (＜025mm). The results showed that ultrafine grinding technology could increase the liquefaction extent and rate. In addition, ultrafine grinding could impove liquefied yield by reducing the particle size and crystallinity of the corn stover.

Abstract:The research on the growth of the foodborne pathogen in the single cell level is popular and necessary for its random and variability, which is different from it in the population level. Based on the related research literatures, the observation methods of the pathogen single cell are summarized as indirect and direct methods. The indirect method is based on the turbidity method and theoretical hypothesis, meanwhile,the direct method is using the optical devices to record the division process of the cells. For the character of the growth in single cell level, the single cell growth prediction model should be built on the stochastic model rather than the deterministic model used in the traditional predictive microbiology. Modelling the stochastic division process by the individualbased method makes it possible to explain the relations between the single cell and its living environments. The observation and prediction for foodborne pathogen single cell is the foundation to control the risk of the food with lowcontamination. Analysis indicates that the pathogen single cell growth prediction tends to be combined with food risk assessment.

Abstract:China is the biggest apple juice concentrate producer in the world, while some security problems, especially patulin still occur in apple juice concentrate industry. These problems are obstacle to produce high quality apple juice concentrate in China. In order to reduce the content of patulin and improve the safety of apple juice, the kinetics of ultrasonic degradation of patulin in apple juice was studied. The pseudofirst order kinetics models were established to investigate the effect of ultrasonic power, frequency and temperature on the degradation of patulin. The results showed that the ultrasonic power was coincided with the pseudofirst order kinetics models in patulin degradation process. The biggest degradation rate was obtained at a power of 490W. The power degradation constant kP value increased with the enhancing power. The power degradation constant kP and the ultrasonic power P was kP=6×10-5P-0.0117. The ultrasonic frequencies were consitent with the pseudo-first order kinetics models in patulin degradation process. The results indicated that 45kHz was the optimal frequency. The frequencies degradation constant kf and the ultrasonic frequencies f was kf=-8×10-4f2+01119f-2.5126. The temperature was coincided with the pseudofirst order kinetics models in patulin degradation process. The results suggested that 30℃ was the optimal temperature. The temperature degradation constant kT and the temperature T was kT=-1×10-4T2+0.0061T-0.0769. The study of patulin degradation kinetics will resolve the pollution problem of patulin and provide the theoretical basis for industry controlling of patulin in the producing of cloudy apple juice and apple jam.

Abstract:Effects of different saccharides, viz. sugar, inulin and trehalose on the glass transition temperature and state diagram of Penaeus vannamei meat (PV) were investigated to improve the storage stability of Penaeus vannamei meat. Moisture adsorption isotherms of PV and Penaeus vannamei meat with addition (w/w) of 10% sugar (PV-S), 10% inulin (PV-I) and 10% trehalose (PV-T) were determined at 25℃ by using the gravimetric method. Differential scanning calorimetry was employed to determine the glass transition temperature (Tg) and freezing point (TF) of samples equilibrated at various water activities. The state diagram was composed of the glass transition line and freezing curve, which were fitted according to Gordon-Taylor model and Clausius-Clapeyron model, respectively. 〖JP3〗The results showed that the adsorption behaviour of Penaeus vannamei meat (PV, PV-S, PV-I and PV-T) 〖JP〗displayed type III isotherms. The GAB model statisfactory described the adsorption behavior of PV, PV-S, PV-I and PV-T. The equilibrium moisture content of PV, PV-S, PV-I and PV-T increased with increasing water activity (aw). Moisture content of PV-S, PV-I and PV-T at a given aw was lower than that of PV. The monolayer moisture content decreased with the addition of saccharides. Tg of PV, PV-S, PV-I and PV-T decreased with increasing moisture content. Tg increased with the addition of saccharides. The state diagram yielded maximallyfreezeconcentrated solutes at 73.2%, 73.4%, 72.6% and 73.4% solids with the characteristic temperature of glass transition being -71.35℃, -64.76℃, -58.36℃ and -59.36℃ for PV, PV-S, PV-I and PV-T, respectively. The corresponding unfreezable waters for PV, PV-S, PV-I and PV-T were 26.8%, 26.6%, 27.4% and 26.6%, respectively. The storage stability and shelf life of meat can be markedly improved by addition of saccharides especially inulin and trehalose.

Abstract:Real-time detection of sugar content plays a crucial role in the estimation of Hetao melon quality. To reduce the effect of size on the diffuse transmittance spectra, an on-line detection testing system based on diffuse transmittance spectra and image information was designed for the evaluation of sugar content of melon. Two main parts (hardware and software) were involved in this device. The hardware includes delivery device, spectrum detection device, image capture device and control system. The software system was designed based on Microsoft Visual C ++ 6.0 language and combined with the software of Omni Driver, FlyCapture2 and OpenCV. With the proposed system, firstly, the spectrum and images of melon were automatically obtained, displayed and saved. Secondly, the sensitive spectrum, color (R, G, B) and volume value of melon were derived by processing spectra and image information. Finally, the sugar content of melon was obtained according to the model of diffuse transmission spectrum and image information fusion. In conclusion, this device could automatically calculate the amount of melon, timely display and save the color value, volume value and sugar content of melon in computer, and detect a sample within 1.2s with root mean square errors of 1.22 for sugar content. The proposed system was showed to be a promising tool for implementing on-line detection of Hetao melon sugar content.

Abstract:Hyperspectral imaging, an emerging analytical technology for quality and safety inspections of agricultural and sideline products, combines the advantages of digital image or computer vision with spectroscopy technology in the whole system. Hyperspectral imaging can simultaneously acquire both spatial and spectral information, which deliver chemical, structural and functional information from the samples. In this work, hyperspectral imaging technology was applied to determine a classifier that can be used for nondestructive defection of the defective features in “No.9 of Zhongyou” nectarine fruit. There were 400 samples from a nectarine planting garden in the Wanan Village in Yuncheng City of Shanxi Province, China, including: crack(50), peel spots(50), malformation(50), hidden damage(50) and normal(200) samples. Hyperspectral imaging technology covered the range of 420~1000nm was employed to detect defects (crack, peel spots, malformation and hidden damage) of nectarine fruit. 400 RGB images were acquired through a total of 400 samples, which included four types of defective features and sound samples. After acquiring hyperspectral images of nectarine fruits, the spectral data were extracted from region of interest (ROI). Using Kennard-Stone algorithm, all kinds of samples were randomly divided into training set (280) and testing set (120). First of all, based on the calculation of partial least squares regression (PLSR), 10 wavelengths at 497nm, 534nm, 657nm, 677nm, 696nm, 709nm, 745nm, 823nm, 868nm and 943nm were selected as the optimal sensitive wavelengths (SWs), respectively. Subsequently, the image of the 876nm wavelength was named as the feature image, then principal component analysis (PCA), mask process, “Sobel” edge detector and “region grow” algorithm were carried out among defective and normal nectarines to extract the defective region. Moreover, ten principal components (PCs) were selected based on PCA, and seven textural feature variables (mean, contrast, correlation, energy, homogeneity and entropy) were extracted by using gray level cooccurrence matrix (GLCM), respectively. Finally, the ability of hyperspectral imaging technique was tested by using the extreme learning machine (ELM) models. The ELM classification model was built based on the combination of PCs and textural features. The results show the correct discrimination accuracy of defective samples was 91.67%, and the correct discrimination accuracy of normal samples was 100%. The research revealed that the hyperspectral imaging technique is a promising tool for detecting defective features in nectarine, which could provide a theoretical reference and basis for designing classification system of fruits in further work.

Abstract:This paper designed an intelligent on-line hierarchical device to grade apple according to its sugar content on the basis of the principle of spectroscopy, and mainly studied the stray light problem of the on-line equipment with receiver at the top of the line. By analyzing the diagram of light path, we analyzed the influence of three different laying ways of Fuji apples on the stray light and put forward a shading treatment to reduce the noise of stray light. The models for on-line predicting soluble solids content (SSC) of Fuji apples were built respectively by using the partial least squares (PLS) regression. The results proved that, for online equipment with receiver at the top of the line, the laying way of apple and the shading treatment were very important. Among these laying ways, “peduncle up and shading treatment” was the best. The parameters of the model are pretty good, with RMSEC of 0.60, RC of 0.94, RMSEP of 0.67, and RP of 0.87. It’s able to achieve the demands of grading apples on-line in practical production.

Abstract:Water absorption influences the germination and metamorphosis of seed. A continuous longterm investigation of germination process and water distribution can help to reveal the water absorption mode of winter wheat (Triticum aestivum L.) seed and lay a theoretic foundation for rational water management during seed germination. The nuclear magnetic resonance (NMR) technique can be used on probe water distribution of seed in a noninvasive and nondestructive way and has been broadly used in the studies on seed and water relationship. The techniques of magnetic resonance imaging (MRI) and T2 relaxation spectrum of NMR were used to continuously investigate the water distribution and variation in a germinating seed of winter wheat for 72h. Images of longitudinal and transverse sections of wheat seed were obtained every hour after the starting of imbibition and used to observe water distributions in different seed tissues. When the seed soaked, its volume increased rapidly at the beginning of seed imbibition (0~6h). Some localized hydrations were already evident in the embryo, coat, and nucellar projection. During the germination prepare phase (6~22h), water content of the coat was higher than that of the endosperm and there was a clear boundary between the bran and the endosperm in the images. Although water accumulated in the coat surrounding the endosperm, there was no evident movement of water directly across the coat and into the underlying starchy endosperm. The water content of nucellar projection was also higher than that of endosperm. Only the water from the nucellar projection gradually diffused into the endosperm. This proved that it was through the nucellar projection rather than the coat and embryo, the water entered into wheat seed. This finding is different from the description in some current textbooks. In this process, the water content of embryo increased and the volume of embryo was increasing at the same time. It showed that embryonic cells began to divide and elongate, and the volume of root sheath became remarkably larger than before. In the stage of germination, the root sheath emerged from a breaking hole in seed coat at 22h and the radicle grew smoothly out at 24h. Thereafter, the volume of shoot sheath started to increase and the seed sprouted at 27h. From then on, seed imbibed water through the radicle and hole in the coat. Water content of endosperm increased and endosperm was activated from bottom to top. Nutrients stored in the aleurone cells near the embryo began decomposing and moved to the central area gradually. The above processes of water transfer and distribution could not be visually detected from the outside with traditional methods. The results of T2 relaxation spectrum analysis showed that there were three distinct phases of wateruptake during the germination of a mature dry seed of winter wheat. During the first phase, water-uptake was rapid initially and then became stable. In the second phase, water absorption rate increased slowly, which was different from the traditionally observed period of stagnation. This phenomenon was probably due to the temperature change effect and magnetic biological effect on plant growth during the NMR detection. In the third phase, water absorption rate oscillated remarkably. This kind of oscillation was probably caused by the periodic water absorption by plant roots. When roots grew over time, their ability to absorb water was enhanced. Thus, the amount of water involved in metabolic activity became larger. When the seed needed a large amount of water for metabolism, the root had to absorb enough water to meet the metabolic demand. After that, the water absorption rate of roots reduced appropriately until the seed required plenty of water for metabolism again. Hence, the water absorption rate of wheat seed oscillated sharply, but with an overall increase in the third phase. In general, the techniques of NMR can help to reveal the water dynamics and distribution in germinating seed more continuously and precisely. The study also realized the direct inside measurement of water content variation in wheat seed, which could not be detected directly with traditional methods. The results will help lay a theoretic foundation for the study and management of germination and water consumption of winter wheat.

Abstract:Effect of wavelength selecting method on the predictive ability of NIR spectroscopy models was studied. Predictive models for 1000grain weight of paddy based on near infrared (NIR) spectra were developed using partial least square (PLS) regression in the wavelength region between 600nm and 1100nm. The resultant standard error of crossvalidation and standard error of prediction were 1.809 and 1.756, respectively, with corresponding coefficients of determination of 0.714 for crossvalidation and 0.659 for prediction. The wavelength regions in which the calibrations for 1000grain weight would be developed were optiminized using six methods: the regression coefficient, mutual information, regression, uninformative variables elimination, genetic algorithm and interval partial least square before establishing the calibrations. Then the NIRprediction models for 1000grain weight were developed based on the selected wavelength regions in the same way as the above. Experimental results showed that, after wavelength optimization, the wavelength regions used in model developing significantly decreased, and SEP reduced while Rv2 and Rp2 increased. Of them, after the wavelength selection was carried out by using the genetic algorithm, the developed model was of the highest Rv2 and Rp2. Moreover, the SEP were decreased by 9.50% and 5.72%, respectively. This suggested that predictive ability of the NIR models for 1000grain weight prediction can be improved after wavelength optimization.

Abstract:To ensure the quality and safety, and extend storage and shelf life of horticultural products across the entire coldchain, a critical step in the postharvest cold chain is rapid precooling after harvest to remove field heat. This work established a threedimensional mathematical model of airinflow and heat transfer for analyzing the aerodynamic and thermal forcedconvection cooling of vented packages simultaneously. A direct model that uses the explicit geometry of stacked products in boxes was developed earlier and was used to study the local and average airinflow through stacks of horticultural products (the package wall, trays and apples). This study is based on an existing twolayer corrugated box for precooling fresh apples. We accounted for the heat of respiration, transpiration, condensation and convective heat flow inside the produce zone. The results show that a reasonable increasing cooling rate and uniformity are obtained with an increase in airinflow velocity to 2.5m/s; any further increase in airinflow velocity simply wastes energy because it leads to a relatively low increase in cooling rate and uniformity. The model was verified by comparing its results to those of experiments. The predicted results were consistent with the measured results. The maximum temperature deviation was less than 1.5℃, and the maximum root mean square error and average relative error for produce temperature were 1.179℃ and 13.6%, respectively. This research thus provides a reliable theoretical basis for improving air-inflow and produce-temperature uniformity and minimizing energy consumption during forcedconvection cooling of produce.

Abstract:As the nighttime replenishment engine, root pressure is one of the most important plant water physiological indices. But root pressure measurement is still a technical problem needed to be resolved. Especially for little plants or herbaceous plants, they are not allowed to be measured invasively. Thus it is a greater technical challenge. On the basis of the combined measurement of stem diameter and sap flow, we attempted to measure the plant root pressure by changing the algorithm orders of the Steppe water flow and storage model. Three greenhouse eggplant samples were selected in the experiment and two groups of five consecutive days of experimental data, which were independent, were displayed. The results showed that from night to dawn, the sap flow rate was zero and the stem grew slowly. Meanwhile, the root pressure began to appear. In the sunny days, the transpirations of eggplant samples were more intensive, the sap flow rates were higher and the stem shrank more significantly. Accordingly, the root pressure increased faster at night. On the contrary, when it was cloudy, the root pressure amplitudes of the eggplant samples were smaller. Obviously，the dynamics of the root pressure were fully consistent with the interpretation for the dynamics of the sap flow rate and the stem diameter,the influence of meteorological data and the known plant physiological water adaptability law. Therefore, it’s feasible to observe the root pressure dynamics of the eggplant samples nondestructively by changing the algorithm orders of the Steppe water flow and storage mathematical model. It allows conducting the similar experiments for other plants.

Abstract:In order to measure the rice flag leaf angle rapidly and nondestructively, a portable system for measuring rice flag leaf angle based on Android smart phone was developed. The rear camera of the smartphone was used for flag leaf images acquisition, and the flag leaf angle was obtained through image preprocessing, lines detection, K-means clustering and vector method. The interfaces and function modules of system software were designed by using the Android programming technology, which realized the extraction algorithm of rice flag leaf angle using JNI and Android NKD to call OpenCV database in the Android platform. It can complete the operational flows of new test establishing, material information inputting, flag leaf images obtaining, angle value outputting as well as interface saving. 80 plants of rices in four varieties were tested to verify the system performance. The test results demonstrated that, comparing with the measurement results of protractors, the average absolute error of this system was 1.34°, the relative error was 2.7%, and the correlation coefficient between the observed values and actual values was 0.997. It was indicated that the proposed system could effectively measure the rice flag leaf angles.

Abstract:To perceive long-term leaf area index, foliage clumping index and canopy density index data of forest canopy structure parameters, an automatic instrument was designed. With this instrument, an effective solution was provided to obtain canopy structural parameter for forest management plan and to collect long-term data for scientific research. The instrument was made up of measuring vehicle, designed orbit and solar energy system. The measuring vehicle was controlled by single chip microcomputer to complete the assigned tasks, such as collecting intensity distribution data of orbital light and obtaining probability distribution function of light spots in different lengths. A large flare elimination method and Bell's Law were used to calculate the forest canopy structure parameters. Leaf area index was measured via a non-destructive optical method, which was applied to crown canopy leaf area index long-term measurement, and then gain the long time serial data. The leaves of 32 plots of experimental forest were tested to measure the accuracy and solver of this method. Results showed that the effective leaf area index obtained via this instrument was similar to LAI-2200 measurement with correlation coefficient of 0.8325, and canopy density index was consistent with what traditional methods did.

Abstract:Network interworking is a key technological bottleneck for the acquisition of mobile video. To solve this problem, based on the studies of video segmentation, compression, annotation and retrieval, the network interworking gateway for mobile video acquisition was designed which can eventually achieve the acquisition of mobile video of vegetables harmed by pests. Firstly, the 3G-324M and H.323 network protocol of video telephone network and IP network were analyzed in detail. Then, an interworking gateway of 3G-324M and H.323 was designed, which included signal gateway and media gateway. Signal gateway is responsible for handling the signal and realizing the control and communication of call level and system level between video telephone network and IP network. Media gateway is responsible for data transmission, realizing the control and communication of media level and data level between video telephone network and IP network. Finally, based on the previous research foundation and the network interworking gateway designed in this paper, a mobile acquisition model was built, and the mobile video acquisition of vegetables harmed by pests was realized. The comparative experiment was carried out on the video acquisition model. Comparing with the traditional methods, it proved that the proposed network interworking gateway and video acquisition model processed theoretical and practical value.

Abstract:In order to monitor the real-time soil moisture, temperature and rainfall in remote area where GPRS communication is not accessible, a real-time soil moisture monitoring system was designed by using Iridium communications, real-time information acquisition and Internet technology. The “Internet of Things” architecture was founded and the self-developed Iridium transparent transmission module as well as real-time data acquisition module were designed based on the terminal module 9602 in short burst data (SBD) transceiver. It implemented intelligent, network-based real-time soil moisture monitoring, as well as historical data querying, downloading and text message alarming according to the preset threshold values. Functions such as sensors and communication failure alarm made it possible for safe, steady, reliable communications. Since August 2011, the system came into operation in Shandong Province, Beijing City and other places. System could be safe, stable and reliable to obtain the soil moisture content, temperature and rainfall. The running result indicated that the data transmission system had the advantages of high reliability, low communication fees and wide coverage. The data receiving rate could reach to 97.2 %, and the communication fee was ￥200 Yuan per month, which achieved the aim of longterm monitoring of soil moisture, temperature and rainfall.

Abstract:Urban-rural land use plan is the foundation of healthily and orderly sustainable development of urbanization and the monitoring of plan implementation is considered as the guarantee. The association of remote sensing and GIS is one of rapid and effective monitoring method for urban-rural land use plan implementation which strongly strengthens the dynamic management of land use plan implementation. We used high spatial resolution remote sensing imagery—WorldView2 with resolution of 0.5m and the objectoriented image analysis method to achieve the classification. The features and thresholds were determined with CART decision tree in objectoriented rule classification. On the basis of classification results, the completion rate of land plan for each plan patch was computed with the monitoring and evaluation of land use plan implementation. Finally, a subdistrict of Fangshan District,Beijing City was taken as the study area to illustrate the method. The results showed that the final overall accuracy of classification was 089 and Kappa coefficient was 0.87. The proposed classification algorithm can meet the basic needs of urbanrural land use plan monitoring. The implementation of land use plan in northeast study area is better than that in the west. The public green land and water area need to be investigated and monitored further as the key objects, at the same time, the density of second type residential building is a little high, while the green landrate is low.

Abstract:Nurse grunting of lactating sows, as a signal to attract piglet sucking, the frequency of which has a fixed relationship with the motive of sows milk secretion, will benefit for building a feeding pattern between the sow and its’ piglets. As an important trait of good maternal behavior, nurse grunting can be one of the criterion in maternal behavior. However, the noises from environment and piglets screams often disturb the recognition and extraction of time and frequencydomain characteristics. The nurse grunting of Xiaomeishan sows combining with the noises from environmental interference noise and piglets’ screaming calls were used in this study. Firstly, according to the energy of noise is evendistributed in the frequency domain, which corresponds to the maximum entropy characteristics, the layers of wavelet packet was selected, and the entropy of corresponding wavelet packet coefficient was calculated. Secondly, the power ratio was calculated to distinguish the types of noise. Finally, the different denoising methods in sound signal with different kinds of noise were compared. The results showed that the main frequency range of a nurse grunting was ranged from 0Hz to 800Hz, while the frequency of piglets’ screaming calls was ranged from 1000Hz to 8000Hz, and the frequency of other interference noise was distributed from 0Hz to 8000Hz. The power ratios of 0Hz to 1000Hz in pure nurse grunting without noise, with environmental noise, and with screaming calls were 1, between 0.85 to 0.97, and between 0 to 0.8, respectively. Meanwhile, with db10 as a wavelet packet basis, the 5 layers and 3 layers wavelet packet transform were used, the main noise ranging from 0Hz to 8000Hz and residual noise ranging from 1000Hz to 8000Hz can be removed. Therefore, the reconstructed signal can be used to analyze the feature of nurse grunting in Xiaomeishan sows.

Abstract:Trends analysis method, wavelet analysis, Mann-Kendall abrupt change test and temporal GIS were used to analyze the spatial distribution characteristics and temporal trends of precipitation based on the annual precipitation observed data from 1952 to 2012 in Sanjiang Plain. The analysis results showed that there was no obvious change trend during the whole time span with several internal variation trends for annual precipitation in five administrative areas, which meant that it existed four main periods of 28, 22, 15 and 6 years for annual precipitation series. For the whole series of precipitation in the Sanjiang Plain, there were no obvious change trends with the following internal variation trends, that was, there was a downward trend from 1955 to 1979, after then an upward trend until 1997, and then there was a downward trend in the remained annual precipitation series. There was an obvious spacial variation for precipitation. It showed that the precipitation in the middle of Sanjiang Plain was more than that in the two sides where from the north to the south during 1952 to 1954, while there was less precipitation in the middle than that in both sides where from the north to the south during 1955 to 1978, and then there was a trend of more precipitation in the north and east, and less precipitation in the south and west in Sanjiang Plain during 1979 to 2012. In addition, for both the whole Sanjiang Plain and each administrative area, the annual average precipitation amounts during 1952—1954 and 1997—2012 were more than that during 1955—1996.

Abstract:Seasonal drought is a main disaster for agricultural production in Guanzhong Plain, and research on spatial distribution characteristics and variation patterns of droughts under the global climate change is of great theoretic significance and applied value. Based on time series of drought monitoring results of vegetation temperature condition index (VTCI) from early March to late May during 2003 to 2014, the structural similarity (SSIM) was applied to analyze spatial characteristics of the time series of VTCI in the plain, and impact factors which affecting the spatial characteristics were analyzed as well. The results showed that the spatial characteristics of VTCI in Guanzhong Plain had distinctive regional variations and spatial heterogeneity, and the structural factor was the main factor affecting the variations. In general, the spatial variations of VTCI were influenced by the distribution pattern of water and heat conditions and terrain, as well as the microtopography, the underlying surface and the human factor. The variations were highly correlated and very sensitive to the changes in the microtopography, the underlying surface or the human factor when they became the dominant factors. Compared with other analytical methods that used some indexes as the indicators of droughts or made statistical models, the SSIM which has the structure information of images was a better approach for indicating the spatial characteristics of the droughts and their variations quantitatively, accurately and conveniently.

Abstract:Agricultural-pastoral area of Northern China is a ecologically fragile belt. Climate change has increased the risk of ecological vulnerability in this region. Besides, it has made the ecological vulnerability more serious because of the pattern of alternant farming and animal husbandry. Therefore, the aim of this paper was to study the responses of vegetation to the change of meteorological factors in agricultural-pastoral areas of Northern China during 2001—2013, using correlation analysis method. First, temporal and spatial variation rules of vegetation growing were explored based on NDVI (Normalized differential vegetation index) and GPP (Gross primary productivity) data. Then, variation rules of temperature and precipitation were found. Finally, we analyzed the responses of vegetation to the change of meteorological factors of different vegetation types using Pearson correlation coefficient method. The results showed that in the research area, vegetation ecological situation was negatively correlated with temperature and positively correlated with precipitation in growing season, while the correlations were on the contrast in nongrowing season. The vegetation ecological situation was positively correlated with temperature and negatively correlated with precipitation. Because the higher temperature will inhibit the vegetation growth than the optimum temperature, while the precipitation in semiarid area could promote the growth of vegetation. However, temperature was very low in nongrowing season, so the increase in temperature promotes vegetation ecological situation obviously and the response of vegetation to precipitation was not obvious because precipitation was not the main factor influencing the vegetation ecological situation in this period.

Abstract:In order to study the anti-lock braking control mechanism of the electromagnetic and frictional integrated brake system and improve the anti-lock braking control performance, the anti-lock braking model was established. And the layered coordinated antilock control method was put forward according to the braking control features of electromagnetic brake and electronic hydraulic brake. The hardware in the loop simulation platform of electromagnetic and frictional integrated brake system was used to verify the validity of this mathematical model. The comparative study which simulated the dry asphalt, ice and snow and docking pavement was carried out on the anti-lock braking performance of electromagnetic and frictional integrated brake system, high-performance and low-performance electronic hydraulic brake system. Conclusions are obtained as follows: using the electromagnetic brake to control the optimal slip ratio in the process of antilock control could fully realize the same anti-lock control effect of high-performance electronic hydraulic brake system with a certain amout of braking intensity provided by low-performance electronic hydraulic brake system. In the design process of the electromagnetic and frictional integrated brake system, the reasonable match of braking performance of electromagnetic brake and electronic hydraulic brake minimizing reliance on the hydraulic control elements of the electronic hydraulic brake would reduce the manufacturing difficulty and cost of the electromagnetic and frictional integrated brake system.

Abstract:In order to promote the overall performance of four wheel drive (4WD) vehicles, its torque distribution was analyzed and a new control strategy was put forward. The 7DOF dynamic model of vehicle was built based on Matlab/Simulink software, including transmission system model, tire model, and submodules, like slip ratio calculation module and tire sideslip angle calculation module. The effects of interaxial torque distribution ratio and intertire torque distribution under the conditions of different roads, speeds and angles on sideslip angle and yaw rate of vehicle were analyzed. The results showed that when the car was steering, the slips of both interaxial torque and intertire torque would have some impacts on the sideslip angle and yaw rate, and the influence of intertire distribution was considerably evident. When the front axle gained more torque, the over steering trend could be improved to a certain extent. When the outside tire gained more torque, the steering ability of vehicle was promoted. When the inside tire gained more torque, the over steering trend could be effectively restrained. Taking the linear 2DOF half vehicle model as the reference object, the torque distribution control system was designed based on the seeker optimization algorithm (SOA) and PID control system. Besides, simulation was carried out with road friction coefficient of 07 and 03, initial speed of 20m/s and front wheel angle of 01rad. The result showed that the proposed control strategy can implement the driver’s steering intention successfully under different road conditions to improve the driving stability of the vehicle. Based on the NI PXI equipment, hardware in the loop (HIL) experiment platform for torque distribution was established. And according to JASO-C-707 and ISO3888-2 vehicle lanechange performance test criteria, the front wheel angle signal was taken as the input of HIL experiment for validating the proposed control system. The result demonstrated that, compared with the ones without control, the peak value of yaw rate and sideslip angle were reduced by 0067rad/s and 0033rad, respectively. Besides, the delayed response was also changed for the better. The experiment result verified the effectiveness of the proposed control system.

Abstract:In order to understand the spray characteristics with methanol temperature and spray pressure changes, a high speed camera and 3D laser phase Doppler particle analyzer(PDPA) was used to research the methanol spray as fuel temperature was 25℃, 50℃, 60℃, 70℃ and 80℃ respectively, and methanol injection pressure was 0.3MPa, 0.4MPa, 0.5MPa respectively. The results show that, with the increase of methanol temperature, the spray atomization quality was improved, the liquid core of methanol jet was reduced, and the spray droplet Sauter mean diameter (SMD) was decreased, meanwhile, the location of main jet zone was expanded from 7mm to 10mm. At the same time, spray penetration and the velocity of droplet was first increased and then decreased with the increase of methanol temperature, and when the methanol temperature reached 70℃, they both had the maximum value. When the temperature of methanol remained the same, the increase of injection pressure can improve the velocity of spray droplets, which contributed to the increase of penetration, moreover, the droplet Sauter mean diameter (SMD) decreased obviously. Thus, in the application of methanol fumigated diesel engine, it is an effective measure to improve methanol atomization by increasing methanol temperature and injection pressure to around 70℃ and 0.5MPa, respectively.

Abstract:Taking into account the strong nonlinearity associated with the dynamics of the electrohydraulic system, a passivity based nonlinear robust control method was developed for it. In the proposed method, the Lyapunov function was designed with the sliding mode of tracking error and the pressure error storage function constructed in the hydraulic passivity theory. Thus the backstepping design process can be decomposed into two cascaded steps: position tracking and pressure tracking. The electrohydraulic system has a redundant dimension, as the two chambers of the hydraulic actuator have different areas. The added internal dynamics of pressure also brought the stability issue. To handle this difficulty, a steady state working point based assignment strategy was presented. This strategy combines force and flow constraint conditions, such that it can assign unique desired pressure for each chamber of the hydraulic actuator. As a result, the nonlinear robust control law was synthesized. Experiments were carried out on a prototype system to validate the effectiveness of the proposed method. The experiment results show that with the developed controller, the electrohydraulic system achieves accurate tracking. The error is no more than 5μm, while tracking constant speed and sinusoidal trajectories. The proposed control method presents good tracking performance and performance robustness. 

Abstract:Hybrid mechanisms have attracted great attention as a robotic mechanism which merges the advantages of serial and parallel mechanisms. In order to obtain structures of hybrid robot, a very simple yet effective method for structural synthesis of hybrid mechanisms was proposed based on GF set. The basic concept and mathematical operation of GF set, and requirements for rotation based on GF set were firstly introduced. Secondly, this paper presents a method for synthesizing hybrid mechanisms by analyzing characteristics of structure composition of hybrid mechanisms. It is shown that structural synthesis of hybrid mechanisms can be developed by the combination of elements of GF set and rotation axis transfer theorem, number synthesis formulas were set up, and a detailed algorithm of type synthesis for hybrid mechanisms was proposed as well. According to the proposed approach, structural synthesis of 3T2R 5DOF hybrid mechanisms was given in detailed. A lot of novel topological structures of hybrid mechanisms were designed. Meanwhile, a method was proposed to analyze kinematic characteristic of hybrid mechanisms synthesized above. Finally, a 3PRP-a-R&RR hybrid mechanism was synthesized to demonstrate the applicability of the novel method of structural synthesis for hybrid mechanisms. The 3PRP-a-R&RR manipulator performs very well with regard to high stiffness and better accuracy and motion transmission capabilities. At the same time a specific application was given. The research provides a general method for hybrid robot mechanism design and the obtained mechanisms do a beneficial supplement to the hybrid mechanism.

Abstract:It is often difficult to achieve further optimization results of machine tool parts in terms of sizes parameters after the topology structure of these parts are determined. Taking the machine bed structure of a horizontal machining center as an object, a twolevel optimization method of the unit structure was proposed, which was based on the analysis and optimization of unit structure, to optimize the whole machine tool bed. Firstly, according to structural features of this machine tool bed, different unit structures were analyzed and compared, and then the round and oval sand hole with original sizes parameters were chosen as the most suitable units to redesign the bed structure. After that, based on response surface method and taking the whole machine tool bed as optimization goal, the secondlevel optimization of unit structure in terms of sizes parameters was achieved. On the premise of minimal change of bed mass, the results of the analysis demonstrate that the twolevel optimization method achieves better dynamic performance of machine tool compared with singlelevel optimization method which only focuses on the optimization of unit structure. To be more specific, the former method can increase the fundamental frequency of this machine tool bed 3 times than the latter method. Besides, when the former method is applied, the biggest resonance peak of this machine tool is reduced by 55.2% in Xdirection, 83.9% in Ydirection, and 82.8% in Zdirection.

Abstract:To suppress grayscale elements in topology optimization for continuum structures, a new doubleSIMP (Solid isotropic microstructures with penalization) method was presented based on standard SIMP approaches. It is found that the SIMP method without sensitivity filter could suppress grayscale elements in the topological structures. Therefore, a twopass method was presented. Firstly, the standard SIMP method with sensitivity filter was employed to generate intermediate design variables; secondly, the SIMP method without sensitivity filter was adopted to update the intermediate design variables again and produce the final solution. Taking simple supported beam as an example, it is successful to apply doubleSIMP method in the topological design of flexible body. According to the results, grayscale elements were suppressed successfully. What is more, the results showed that smaller structural compliance could be obtained through doubleSIMP method. The meshdependence problem of doubleSIMP method was also better. Besides, to suppress the grayscale elements, the standard SIMP method would need to increase the penalty factor. However, the bigger the penalty factor was, the more the iterations were. The doubleSIMP method didnt rely on the penalty factor. Compared with standard SIMP method, there were not extra parameters and constraints in the doubleSIMP method. As a consequence, the applicability is similar between the two kinds of methods.