Abstract:In order to solve the uneven wear problem of frictional disks of HVD clutch and improve its response speed, a new HVD clutch with double piston structure is proposed, and its working principle is analyzed. Based on mathematics model of frictional disks, the oil dynamic balance function and transfer function for the new HVD clutch are obtained, and its dynamic characteristics is studied by theory analysis and simulation. The results show that compared with the ordinary HVD clutch with singular piston, the new HVD clutch has a faster response speed. The response time can reduce from 52s to 22s when the output speed is given as 80rad/s.

Abstract:Charging characteristics of accumulator play an important role in the safety and reliability of hydraulic braking system. The charging characteristics of an electro hydraulic braking system and its key structural element, priority unloading valve, were studied. In the charging process of accumulator of the braking system, the mechanisms of the priority unloading valve and its system components were analyzed to establish the mathematical model for it and to build the simulation and test platform for the charging system. The dynamic characteristics of the accumulator charging system were studied; the changing laws of the parameters such as pressure, flow and time, were gained; and the response law of the priority valve to accumulator charging characteristics was revealed. The research results show that the designed priority unloading valve can meet the requirements of accumulator charging characteristics.

Abstract:Conventional optimization theory cannot work without the optimal solution. In order to improve this situation, a mathematic model for the design of semi active suspension (SAS) and electric power steering (EPS) integrated control system was established based on satisfactory optimization theory. Then the satisfactory optimization method of SAS and EPS integrated control system was proposed. On this basis, SAS and EPS integrated control system and real vehicle road test system were designed. Real vehicle road test was conducted based on the simulation and then the effect on the dynamic performance of car was analyzed. The results show that the theoretical research is consistent with the test results. The peak value and the standard deviation of the front suspension deflection are reduced by 14.00% and 14.56%, respectively, meaning that the impact of suspension on the car body become smaller. The peak of tire displacement is reduced by 1134% so that the tire ground performance is increased. The peaks of the suspension yaw acceleration and the roll angle are decreased by 13.60% and 14.41%, respectively. And their standard deviations are decreased by 15.80% and 16.08%, respectively, which means that the car`s handling stability is greatly enhanced.

Abstract:In order to study the application of fractional calculus in the control of semi active air suspensions, a 4-DOF nonlinear dynamic model of semi active air suspension system was built. A modified-Oustaloup filter algorithm was adopted to simulate fractional calculus. The simulation model of semi active suspension with fractional-order sky-hook damping was developed. And its simulation results were compared with those of passive suspension and semi-active suspension with integral-order sky-hook damping. The comparison results indicate that in contrast to passive suspension, when the car is running at the speed of 20m/s on grade B road, the integral-order and fractional-order sky-hook damping control strategies reduce weighted RMS (root-mean-square) values of vehicle body vertical acceleration by 31.9% and 43.9%, and decrease RMS values of pitching angular acceleration by 23.1% and 30.7%. The results further show that the semi-active control based on fractional calculus could suppress vehicle body resonance more effectively.

Abstract:In order to achieve engineering application for a new 8 speed automatic transmission, a simplified dynamic model for hydraulic automatic transmission was built and key control parameters that affect shift quality were analyzed. For the four basic shift types, the ideal curves of shift clutch and engine control were set up. Based on torque estimation method, PI slip control algorithm and engine coordinated control theory, the control model and transmission controller were developed for three shift phases which included rapid fill phase, torque phase and speed phase. In rapid fill phase the command pressure at oncoming clutch was set as the kiss point at which point the oncoming clutch just transmits torque , in torque phase the torque change rate at off going clutch was controlled as similar as oncoming clutch based on torque estimation, in speed phase the engine torque reduction control was added to reduce the shift jerk. An environment of the rig and vehicle tests was built and the testing results obtained in extreme conditions can verify the accuracy and feasibility of this shift control strategy. The peak jerk during shift process was reduced significantly and the smooth gearshift was obtained. The strategy has high value for engineering application.

Abstract:A test bench composed by induction motor and dc motor is proposed to test the performance of power source on EVs. The test bench is a complex electromechanical coupling system with mechanical, electrical and magnet fields. The electromechanical coupling model of the system was built. The nonlinear system was linearized with the help of α order integration inverse system. The adaptive fuzzy neural network control was applied to the system based on the inverse system control. That also leads to a better decoupling simulation and experimental results. Both of the feedback of AC motor speed and DC motor torque follow the targets. The variations of voltage, current and power on the DC bus of the battery connected with induction motor can be observed, which provides the theoretical foundation for the research on the hybrid energy storage system.

Abstract:Magnetic circuit parts as key components in GDI injector require highly processing technology, but the traditional metal cutting exists the problems of low efficiency, low precision, low material utilization rate and unstable performance, so the metal injection molding technology (MIM technology) was introduced into the GDI injector production. According to the forming characteristics of GDI injector and the performance requirements of the MIM technology, the Fe based nanocrystalline soft magnetic alloy powder Fe73.5Cu1Nb3Si13.5B9 was selected as the molding material of GDI injector magnetic circuit parts, and the structures of the magnetic circuit parts were optimized. Through tracking test of the whole sample production process, the advantages of the MIM technology compared with the traditional technology were analyzed. The MIM technology has advantages in manufacture, physicochemical properties, soft magnetic properties. The characteristics of the GDI injector based on different molding technique were compared by the method of 3D electromagnetic finite element simulation and experiment. The results show that, the simples which were processed by the MIM technology effectively reduce the influence of the skin effect and eddy current loss, accelerate the starting current rise rate, shorten the dynamic response time, increase the dynamic injection quantity and expand the linear range of dynamic fuel injection quantity. The comprehensive performance of GDI injector is improved significantly. 

Abstract:A transplanting robot aiming at the new spiral culture column was developed. The electromagnet type and structure parameters of the double-needle electromagnet driven end effector were decided with geometrical and force-balance analyses. The coordinated motion simulations of plug tray seedling transplanting robot for column cultivation were carried out on a virtual prototype to find out the optimal structure parameters of the manipulator, the optimal layout of the system and the time sequence of coordinated motions of different components. And the flow diagram of coordinated motion was constructed. Tests of the real prototype indicate that the horizontal and vertical positioning errors of the manipulator are 2.24 and 0.63mm, respectively, and the success rate of transplanting achieves 94.7%. The working efficiency of transplanting to columns no higher than 1.2m achieves 750 hills per hour, and the seedling picking-up time is only 0.2s, which can meet the practical requirements of automatic transplanting of column cultivation.

Abstract:In order to judge fruit quality real timely, three conditions of litchi fruit, immature, mature and appearance rot after mature, were analyzed by using the fruit images of different growth periods in natural environment. The YCbCr color space model was selected and the exploratory analysis method was used to analyze and estimate the Cr component of litchi images of different parts, different illuminations and different growing periods, and the threshold ranges of Cr components of mature and immature litchi fruits was determined; for mature litchi, the fruit edge detection and Hough circle fitting processing were carried out on the Cr component diagram to mark litchi fruits. And then the texture statistics and the method that combining the color feature and area ratio of different parts of litchi fruit were used to judge litchi fruit deterioration. Finally, the vision intelligent judgment for the immature, mature and appearance rot of litchi fruit was realized and an intelligent system to identify litchi fruit quality was built. The test results show that the accuracy of identify litchi fruit quality is 93%.

Abstract:In order to detect cotton position on a plant, an infrared distance measurement device and the computer image processing technology, combined with the growth characteristics of cotton, were used to measure the distance of single cotton. The infrared measurement model was established in the distance of 0.7m to 1.6m. The distance image of plant surface point cloud was obtained with the measurement accuracy of 0.008 5 m. The Gaussian filter size was designed with the standard deviation of 0.65. 1D Gaussian filter was used to smooth the plant image and 2D Gaussian filter was used to obtain the gradient image. With the strong threshold of 0.2m and the weak threshold of 0.08m, the closed loop edge was constructed based on Canny edge detection operator. The image of cotton area was extracted by morphological operations, and the cotton sticks background was removed. Peak filter was used to weaken the adhesion and overlap of the cotton image. The cotton distance image was segmented based on watershed algorithm to extract the single cotton image and obtain the distance. The results show that the image recognition rate of single cotton on the plant is 91.3% and the correlation coefficient between the infrared and artificial measurement results is 0.992 2, which provides parameters for cotton picker robot to plan motor path.

Abstract:An intelligent controller using adaptive neuro-fuzzy inference system was developed to control the force of gripping fruits and vegetables of an agricultural robot. The inputs of the controller are the current griping force and the detail coefficients of discrete wavelet transform of the signal from slipping sensor fixed on the robotic end effector. The output of the controller is the displacement of fingers of the end effector. Firstly, a subtractive clustering was applied to generate a fuzzy model, and the radius of the clustering was adjusted to optimize the fuzzy rules. Then methods of sampling training data were introduced, and a hybrid training algorithm consisting of the gradient descent and least square algorithms was implemented to tune antecedent parameters and consequent part of the model. Finally, the experiments of controlling the griping force were carried out. It shows that the controller is able to adapt itself to differences of the fruits and vegetables in mass and surface friction characteristics. Moreover the controlling overshoot of griping force is restrained successfully and less than 0.8N, which prevented the grasping of fruits and vegetables from mechanical destruction.

Abstract:Heuristic dynamic programming (HDP) design for autonomous mobile robot was put forward to solve the goal seeking with obstacle avoidance problem. A method of sensor detecting was proposed, and the method for system normalizing the sensors’ inputs information was discussed. The input/output signal and reinforcement signal were defined, and a self learning strategy for robot seeking the goal with obstacle avoidance was proposed. A continuous reinforcement signal to improve the systems preferential decision between goal seeking and obstacle avoidance was designed. To verify the learning ability of our algorithm, three different simulation experiments were designed: same goal with different initial points and directions, same initial states with different goals, moving goal. The simulation results show that the HDP approach presents an effective learning ability for autonomous mobile robot on goal seeking with obstacle avoidance problem.

Abstract:A leveling control system is necessary for keeping the plow level during the laser controlled paddy field leveler’s operation. A nonlinear double closed loop control scheme is proposed to minimize the overshooting in the controlled inclination angle, where the angular speed control and inclination angle of the plow are controlled in the inner and outer loop, respectively. The overshooting minimization is achieved by manipulating the angular speed of the plow according to the remaining path nonlinearly to the level position so that the plow approaches to the level position with zero angular speed. Also included are the hydro mechanical plant’s transfer function analysis for the leveler and the overall control system design. Such an control system was implemented incorporating AHRS(heading and heading reference system) and TMS320F28035 microcontroller, and lab and field tests with a prototype paddy land leveler show that the plow would respond to leveling error quickly, returning to the level position asymptotically with a maximum leveling deviation within ±1°.

Abstract:A finite element code ABAQUS/Explicit was used to model three-dimensional soil compaction process. Drucker-Prager Cap (DPC) model was used as soil constitutive model. The behavior of the soil bionic press roller interface was investigated and compared with a conventional roller. Simulation results show that the artificial strain energy is approximately 0.1% of the internal energy, indicating that hourglassing exerted very little influence on the simulation results. For the conventional press roller and bionic press roller, the relative error of traction resistance between the simulation and soil bin test results are 11.47% and 2.38%, respectively. The simulation results agree well with the experimental results. It proves that the finite element model is reliable. The Mises stress nephogram, the contact area between soil and press roller and the displacement nephogram are adopted to compare the simulation results of the two press rollers. The simulation results show that contact stress between the bionic roller and soil is significantly higher than that of conventional roller, which is beneficial for crushing clods. The contact area between bionic roller and soil is 79.05% lower than that of conventional roller, which is helpful to reduce soil adhesion. Also this result is proved by the soil bin test results, which shows that the bionic roller can reduce 52.78% of soil adhesion. Adjacent ridge structures of the bionic roller can properly constrain the flow of soil, thus avoiding the hilling phenomenon in compaction process. The two press rollers show little variance in vertical displacement and have similar compaction resistance, but bionic roller is more conducive to compact topsoil. The soil displacement in the direction of roller width caused by the conventional roller is greater than that of the bionic roller, which makes the conventional roller consume more power. The soil bin test results show that the bionic roller lowers the resistance by 28.66% as compared with conventional roller.

Abstract:Singular point distribution method is an important approach in axial blade design for computing and shaping midline of axial impeller airfoils on a developed flow plane. The principle involved in this method is to place continuous vortices along the midline to replace airfoils, to induce a plane velocity field meeting the requirement of specified pump performance, and, finally, to form the required microbending airfoil midline. A proper strength function of vortex sheet is a primary to realize this object. It is found that the commonly defined strength function is only suitable for flow conditions in runner plane airfoils. We presented a new vortex strength function differing from the traditional one and justified the reasonableness of the new theorem by potential flow theories: the resultant velocity normal to the sheet is zero, in compliance with the fact that the flow can’t penetrate the solid airfoil; the computed velocities at the front and rear points of the airfoil in a uniform stream indicate these two points are in agreement with Kutta-Chaplygin conditions. The paper formulates a new way for axial airfoil design.

Abstract:With the aim to optimize the centrifugal pump load matching characteristics with a photovoltaic system, a method to estimate the system configurations was established at first. In sunny conditions, the basic parameters of centrifugal pumps in the highest solar radiation level were obtained through this method. Several sets of centrifugal pumps with different ratios between rated flow and maximum flow were matched with the PV system, and the system performances in different conditions were analyzed. According to the results of comparisons, a group of load characteristic parameters were selected for selecting pump model and testing. Results show that the more oblique of the characteristic curve of centrifugal pumps, the more suitable for the PV system. The efficiency of this system increases with the ratio between maximum flow and rated flow, and is higher when the ratio is between 1.1~1.2. This study provides a reference for PV centrifugal pumps load model selection and optimization.

Abstract:For the study of screw pump internal flow and pressure pulsation characteristics, ICEM-CFD was applied to structure mesh generation for flow components, and the steady and unsteady simulations were carried out by CFX software to get the pump internal flow and the pressure pulsations of the monitoring points. The results are as follows: under 0.8Q condition, there is local high pressure area and whirlpools existing at the junction of the hub and the blade, which gradually decrease and eventually disappear as the flow rate increasing; under the design condition and 12Q condition, the internal pressure and velocity distributions gradually become uniform, the flow is stable and the inflow is smooth. The pressure coefficient fluctuation amplitudes of the inlet and outlet of guide vane are significantly greater than that of the impeller and have obvious peaks and troughs; the pressure pulsation mainly generates in the low frequency region, reduces with a cyclical trend, and its amplitudes are generated at the frequencies that are the whole number multiple of the natural frequency. Among the monitoring points, the pressure pulsation amplitude of the inlet is the largest, and the amplitude of blade rim side is larger than that of the hub side. Pressure fluctuation amplitudes of monitoring points at the outlet are uniform and small. In the whole process of pump operation, the smooth downward flow head curve and power curve are obtained, and there is no saddle area and overload phenomenon occurred. These meet the design requirements. Prediction curves are basically consistent with the experimental curves. It indicates that the numerical simulation is accurate and has certain value for spiral axial flow pump design.

Abstract:Based on COMSOL (35), two dimensional transient cross sectional models were used to investigate water and solute transport in the soil column coupled with variable sand column forms, with “a” denoting no sand column, “b” with one vertical middle sand column, “c” with one long slanged sand column, “d” with two long slanged X shaped sand columns. The results showed that sand column obviously increased the transport efficiency of water and salt, which may attribute to the higher hydraulic conductivity and higher diffusion coefficients in sand columns than clay loam coastal saline. The efficiency of sand column depends on its position and its angle accordingly. The slanted columns were overall superior to the vertical ones in transport efficiency. Generally, “d” is the best type, “c” is the second best and “b” is the third, according to the efficiency of salt leaching and the efficiency of the utilization of water resources.

Abstract:In order to define the spatial distribution of soil air permeability and do correlation analysis of its impact factors in basin scale, researches in Jinghui irrigation district at the middle of Shaanxi province were made. Based on the spatial analysis function of geographic information systems, the results show that the optimal fitting model for air permeability is an exponential model, and the statistical method is suitable to simulate the spatial structure and variation characteristics of soil air permeability. The bulk density, saturated moisture content, saturated degree and soil air permeability’s spatial autocorrelation C/(C+C0) are all greater than 0.9. It shows the spatial heterogeneity induced by the autocorrelation has a strong degree in the spatial heterogeneity of the study scale. Recommend sampling distances of air permeability is 7.5km. Significant correlation is found between bulk density and soil air permeability, and the absolute value of Pearson correlation coefficient is 0.595. High correlation is found between soil air permeability and saturated degree, and the absolute value of Pearson correlation coefficient is 0.959. The bulk density and the saturated degree are proved to be the main impact factors by interactive correlation analysis between air permeability and soil physical parameters. The influence ranges of bulk density and soil saturation degree on air permeability are both from -20km to 20km at 95% confidence level.

Abstract:Fuzzy c means clustering was used to define soil nutrient management zones. Remote sensing (RS) data, soil sampling data, and a combination of both were tested to identify which data source was the best for partitioning optimum zones, using a geographical information system and various statistical techniques. The study area was a region of large scale drip irrigated cotton cultivation in China. For all three data sources, the area was portioned into three zones. With the aim to confirm the resulting zones, the coefficient of variation of the nutrient index was calculated for the RS data, soil data, and combination of both types of data. There was no significant difference among the results calculated using the three data types. The least spatial variation in soil nutrient content was found within the same management zones, with larger variation between zones. The highest degree of conformity (91.36%) with zones derived using actual cotton production data was found for the management zones defined using the combination of RS and soil data. Using soil nutrient data alone, the degree of conformity was lower, at 84.40%. The lowest conformity (75.46%) was found for the zones based on the RS data alone (using the normalized difference vegetation index). The method proposed here, using fuzzy c means clustering and a combination of RS and soil sampling data, can be useful in determining zones for optimal fertilizer application and resource management in cotton systems.

Abstract:Taking farmland of oasis in Xinjiang Manas as the example, in order to timely, accurately and dynamically monitor water and salinity of saline soils,the partial least squares regression (PLSR) for model was applied to model the moisture and salt content of different moistures and salt soils based on hyperspectral analysis technique, the stability and predictive ability of the model was validated. The results show that the prediction precision of soil salinity and moisture were effectively improved through continuum removal (CR) and the logarithm of first order differential (lgR)′ in 12 kinds of data transformation. The prediction models were better when soil salt content was less than 819dS/m, R2cal were greater than 079, R2val were greater than 064, with no significant difference between RMSEP. The prediction precision was poor when soil salt content was greater than 10dS/m with R2val less than 045 in the moisture prediction models. The better prediction accuracy when the moisture is less than 15%, R2cal were greater than 077, R2val were greater than 064,with RMSEP less than 46. The model prediction accuracy was poor when soil moisture greater than 15%. It was concluded that the large soil moisture, salt content will have a significant impact on salt water prediction model.

Abstract:In order to investigate the law of ammonia volatilization and nitrogen infiltration in the process of biogas slurry surface application, the rules of ammonia volatilization of soil surface and the infiltration of total nitrogen, ammonia nitrogen, nitrate nitrogen and water in vertical soil profile were systematically explored by soil column experiments at room temperature. The experimental results show that the ammonia volatilization mainly happened in the first five days, which accounts for 97% of total amount. And the maximum daily ammonia volatilization is 93.24mg/(L〖DK〗·d), which appeared from the second day to the third day. The infiltration rate of ammonia nitrogen lagged behind the water infiltration. The distributions of water, ammonia nitrogen and total nitrogen mainly exist in 0~5cm soil. And the distribution area of nitrate nitrogen is 0~15cm, bigger than that of ammonia nitrogen. The variation of ammonia nitrogen of topsoil has a high to low trend. And the whole variant trend of nitrate nitrogen of topsoil is opposite to the ammonia nitrogen.

Abstract:Hetao irrigation district in Inner Mongolia was selected as the study site. The domination principle of synergetic was used for analysis. Order parameters were established in three subsystems of the plantation system: resources environment, socio economic and plantation structure subsystem, respectively. The order degree and coordination degree of the system from 1960 to 2008 were calculated by a system identification model based on synergetic theory. Furthermore, the changes on the coordinating degree were analyzed as well as the synergy and difference features. The threshold values were then put forward for informing reasonable plantation structure. The results show that the coordination degree of the plantation system presents fluctuation changes, but the changes are relatively low. Particularly, a break occurred in 2004 and shows significantly difference characteristics. Finally, a reasonable threshold interval of proportion for crop plantation was put forward. It is grain (47.82%，62.66%) and economic crops (24.64%，43.49%). 

Abstract:As a kind of advanced oxidation technology, ozone aeration has been widely used in wastewater treatment and disinfection. Ozone aeration of piggery wastewater also significantly affects the forms of phosphorus and effectiveness, which have important effects on the utilization of pigfarm effluent regeneration in farmland. In order to study the influences of different durations of ozone aeration on the phosphorus content and form transformation in anaerobic swine wastewater, the experiment, sampling and measuring the content of phosphorus in different forms, was conducted on self designed apparatus, with five different durations of ozone aeration, 0min, 10min, 20min, 40min, 60min, respectively. The results show that different durations of ozone aeration remarkably affect the content of phosphorus in different forms in wastewater system. Specifically, the contents of total soluble phosphorus, soluble inorganic phosphorus, total organic phosphorus and particulate organic phosphorus show decline trends with the magnitudes of 30.28%, 41.80%, 34.92% and 79.53% at the end of aeration lasted for 60min, respectively. By the contrary, the contents of soluble organic phosphorus, total particulate phosphorus and particulate inorganic phosphorus show upward trend, which increase by 105.11%, 46.74% and 123.86% at the end of 60min （P<0.05), respectively. Meanwhile, the loss of gaseous phosphorus is also detected in the absorbing liquid with trace amount, which only occupying 0.38% of the total phosphorus. The total phosphorus content in the wastewater system is basically unchanged. The loss of available phosphorus and the recovery of particulate phosphorus in the swine wastewater after ozone aeration should be taken into consideration.

Abstract:Considering the main problems of the small working volume, less functional on real time monitoring and feedback control of current experimental composting reactor system, an experimental type of aerobic composting reactor system was designed and manufactured on the basis of existing research. According to the principle of statics and thermodynamics, the key functional units of the composting reactor system were optimized. Automatic control system for the aerobic composting reactor was introduced for a better control of composting process. Testing experiments were carried out to check the usability of the designed composting reactor system. The period of composting temperature higher than 50℃ lasted 8.1, 7.2 and 4.8 days for each layer in the reactor system, respectively. The final pH value is less than 8 for composting materials of all layers. The final germination index (GI) for composting product of each layer are higher than 85%, respectively. All the three results show that the composting reactor performs well.

Abstract:Accurate calculation and prediction of food freezing process is important for product quality control, device design and energy cost reduction. However, it is a great challenge to find a general method to describe and forecast this process because of its complex mechanism. With the development of computer performance, the application of numerical simulation has gained more and more attention in study of food freezing process. Based on the analysis of food freezing process mechanism，the development of numerical simulation methods and their applicationsin food freezing processes were summarized, so as to provide some guidance for the further research and application of this technology.

Abstract:The effects of packaging on food freezing was investigated using both modeling and experimental methods. First, CFD method was employed to model the freezing condition of food in freezing chamber, including air temperature, air velocity and turbulent intensity, which was then used to calculate the surface heat transfer coefficient of food product. Empirical relations for free convection and radiation were used to simulate the heat transfer inside the air layer between food and packaging material. Fourier formula was applied to model the heat transfer inside food. Finally, an iteration scheme was used to combine all parts together. Freezing experiments were conducted in a small freezer to verify the model, which showed encouraging agreements on freezing curves of food at different locations. Packaging has a big influence on food freezing, food with different packaging differs greatly in freezing process. The thermal resistance of air layer in packaging changes in a reverse trend of food temperature drop.

Abstract:In order to scientifically monitor sensory quality changes of chilled pork during cold chain logistics, the sensory characteristics of pork samples from distribution center, short distance supermarket and long distance supermarket during the progress of cold chain logistics were investigated, including odor, color, springiness, cooking odor and overall acceptability of pork samples. The distribution and the probability of different sensory indicators scores were studied by normality test. The key evaluation indicators was obtained by using sensitivity analysis and regression analysis, then according to its data distribution characteristics and its diagnostic value to overall acceptability, the control charts were designed to visualize the fluctuation of sensory characteristics distinctly. The results showed that: overall, there were significant difference in the sensory quality of pork samples from distribution centers, short distance supermarket and long distance supermarket; color is the sensitive indicator to evaluate overall acceptability, and its mean standard deviation control chart were designed; there were more sensory quality fluctuations in distribution center, and its process capability index was lower, thus it was need to improve quality management. The product quality fluctuation and its qualified ratio were distinctly visualized by mean standard deviation control chart, and it would provide scientific management method for monitoring pork appearance changes in cold chain logistics.

Abstract:In view of the situation that the kinetic model which is necessary for the traditional time temperature indicator (TTI) selection method is complex and inaccurate for the multiple regressions, a convenient and intuitive method based on the contour lines was proposed. The method is demonstrated in theory, and analyzed with the traditional method through an experiment about Muscat Hamburg grape and four kinds of TTI. The result shows that the TTI of Vitsab M25-2 could be considered as the best candidate to monitor firmness losses of Muscat Hamburg, and this is similar to the result from the traditional kinetic model. Meanwhile, the differences of the contour lines between the grape and TTIs are positive correlated with the differences between the activation energy of them, which confirms the reliability of the TTI selection method based on contour lines.

Abstract:Taking a cold store as the experimental objective, the inside environment, air curtain and outside environment of the cold store were simulated by a 3D coupled model. The unsteady simulation of the flow field of the air curtain was performed by using a CFD software and the temperature field inside the cold store was measured. The effects of the supply velocity, supply angle and jet width of the air curtain on its isolation ability were analyzed under the condition that the door and the air curtain were opened simultaneously. The results show that there is an optimal supply velocity and angle to make the air curtain has its best isolation performance and the temperature field inside the cold store has the smallest fluctuation. However, the jet width should not be too large. The optimal supply velocity, angle and jet width of the air curtain for this cold store are 8m/s, 15° and 0.04m, respectively.

Abstract:The effect of aggregate characteristics on rheological properties of soy protein dispersions was studied. Aggregated protein was produced by heating a solution of soybean protein isolate (SPI) at 0.04g/mL and 0.09g/mL. The higher protein concentration resulted in a larger aggregate size with a higher intrinsic viscosity and a higher accessibility of thiol groups. The protein fraction in native SPI had the smallest size and the lowest intrinsic viscosity. The same trend was observed for the shear viscosity after concentrating the suspensions containing aggregates to around 0.14g/mL. Suspensions containing aggregates that were produced from a higher concentration possessed a higher viscosity. After reheating the concentrated suspensions, the suspension from the 0.09g/mL aggregate system produced the weakest gel, followed by the one from 0.04g/mL, while the native SPI yielded the strongest gel. Our results prove that the process of soybean protein aggregation opens a new door to manipulate the gel strength of concentrated protein systems, without having to alter the concentration of the protein.

Abstract:The aim of this work was to study substrate speciflcity and inhibition kinetics of ascorbic acid, 4-hexylresorcinol, L-cysteine and citric acid on PPO obtained from honeysuckle. The results show that the best substrate is chlorogenic acid because of the lowest Km value 0.0059mmol/L; ascorbic acid, 4-hexylresorcinol and L-cysteine demonstrate reversible inhibition, and their IC50 values are 0.062，0.053，0.140mmol/L. Citric acid shows irreversible inhibition to PPO with IC50 value of 0.048mmol/L. Lineweaver-Burk plotting show that ascorbic acid, 4-hexylresorcinol and L-cysteine are mixed type, non competitive and anti competitive inhibitors, with the inhibition constants KI of 1.620, 4.587, 0mmol/L, and KIS of 1.995, 0, 3.780mmol/L, respectively.

Abstract:With the aim to clarify the film-forming characteristics of fish skin gelatin at high temperature, the effect of protein concentration of film forming solution on the properties of edible films based on the tilapia skin gelatin was investigated. The gelatin was extracted from tilapia skins which were obtained from fresh fish during fillet processing. The obtained gelatin were swollen in distilled water for 30min and then dissolved at 60℃ to obtain the film-forming solutions (FFS). Glycerol as a plasticizer was added at the concentration of 20% of gelatin, and the concentration of gelatin dry basis in FFS was adjusted to 5%, 10%, 20%, 30% and 40%. Air bubbles in FFS were removed by a hybrid mixer. Subsequently, the FFS was cast onto a rimmed silicone resin plate (50mm ×50mm) and dried at 100℃ for 30min, and the obtained films were then conditioned at (25±0.5)℃ and (50±5)% RH for 48h. After having been peeled off, the resulting gelatin films were used for the determination of mechanical properties, water resistance properties and heat shrinkage (HS). Furthermore, the formation mechanism of skin gelatin films was elucidated by electrophoretic analysis, differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT/IR). As a result, the tensile strength (TS) and HS of gelatin films prepared at 25℃ (Control) could reach up to 67.72MPa and 48.75%, with the matter solubility (MS) and protein solubility (PS) of films was 22.97% and 15.59%, respectively. When film-forming solution with protein concentration of 5% was dried at 100℃, the TS and HS of the resulting films was decreased to 8.99MPa and 8.13%, while the MS and PS was increased to 33.36% and 37.47%, respectively. However, the values above were all gradually close to those of the control with increasing the protein concentration to 40% in the film-forming solution. On the other hand, based on the analyses with DSC and FT/IR for the gelatin films, it was found that the triple helical structure of tilapia skin gelatin was destroyed when the film-forming solution with lower protein concentration was dried at high temperature, resulting in the gelatin films obtained with poor mechanical properties and water resistance ability.

Abstract:Ventilation resistance characteristic of grain layer is the key influence factor to the drying uniformity and energy consumption, is also the theoretical foundation parameter for layer design and fan selection. The traditional empirical formulas of ventilation resistance of grain layer are low precision and ignore the complicated changes and nonlinear uncertainty problems of grain layer porous media. The pressure loss factors were discussed based on the traditional Ergun model. By testing the airflow resistance on test platform, dividing the air velocity into subsections by the exploratory analysis method, and introducing an error influence factor λ, a new pressure field model of variable layer was derived based on the Ergun model. The optimal resistance characteristic curve was given, and the relationship between the ventilation resistance and layer thickness was built. The results show that when the air velocity is less than 0.2m/s, the λ is 1; when the velocity is between 0.2m/s and 0.4m/s, the λ is 0.89; and when the velocity is between 0.4m/s and 0.6m/s, the λ is 0.79.

Abstract:Agricultural internet of things (Ag-IoT) is the highly integrated and comprehensive application of the new generation of information technology in agricultural field. Ag-IoT is playing an important leading role in the agricultural informationization of China. It has changed the traditional agricultural production mode, and it is also promoting the transformation from the traditional agriculture to intelligent and precision agriculture. The concept of Ag-IoT and its technical system framework were firstly introduced. Then the research status and advances of sensing technologies, communicating technologies and key application technologies used in Ag-IoT were reviewed in detail. The challenges and problems existing in the development of Ag-IoT in China were further analyzed. Based on the analysis, countermeasures for the applications and development of Ag-IoT of China in many aspects were proposed, such as research priorities, development layout, advancing directions, application models and mechanisms for sustainable development.

Abstract:The field experiment was carried out in three cotton growing seasons from 2011 to 2013. Cotton canopy normalized difference vegetation index (NDVI) was obtained by GreenSeeker at full bud stage, flowering stage, full boll stage, early wadding stage. Yields, from different nitrogen application rates, were collected at harvest stage and compared with each other. Canopy NDVI, changing with nitrogen application level and growth period, were analyzed, separately. Furthermore, the correlation analysis was done between yield and canopy NDVI. Yield estimation models were established for cotton based on NDVI value. Results indicate that, in the four growth stages, with N rates increasing, canopy NDVI value presents a trend of “low high low”. And the correlation coefficient between canopy NDVI and yield is 0.7137，0.8479，0.8979，0.6926, respectively, and significantly positive correlative at flowering stage(P=0.0034) as well as full boll stage (P=0.0008). Regression between predicted yield and measured yield values of the year of 2013 shows that the correlation coefficient is maximum at full boll stage (R2=0.9082), and the root mean square error(RMSE) is 301.67kg/hm2, while the relative error (5.15%) is minimum. The results suggest that it is especially feasible to use canopy NDVI to estimate yield of cotton at the full boll stage.

Abstract:A hybrid method for small river-water extraction using TM images, covering Hengshan County in Shaanxi Province and acquired in August 20, 2010 and August 2, 1986, is proposed. After the pretreatment of the original image data, WFS feature space is built. Then, WFS is segmented to remove the influence of background spectral interference by aid of overlay analysis with thematic maps, such as present land use map, topographic map and drainage map. Next, the multispectral images containing the preliminary water distribution information are processed with LBV transformation and object oriented segmentation. Further, the precise extraction of river water can be achieved by using SVM supervised classification and mathematical morphology open close operator. Finally, water dynamic analysis is accomplished by adopting the precise water change information acquired from the above results. Results show that using the method provided can get precise water distribution information in Hengshan County, especially can improve the identification accuracy for small river. The map accuracy of water extraction results in 1986 and 2010 are 0.921 and 0.875, respectively, and the user’s accuracy are 0.913 and 0.862, respectively. The hierarchical extraction method proposed is feasible and reliable for small river-water extraction, can reduce the error of loess hilly and gully region identification, significantly.

Abstract:The Xylosma racemosum forest located in Huairou District of Beijing was chosen as research objects, texture parameters as well as derivative texture indices of different window sizes from ALOS fusion imagery with resolution of 2.5m were measured. Stepwise multiple regression models were developed to describe the relationship between textures (including texture parameters and derivative texture indices) and field measurements of stand volume. The main objective was to compare estimation accuracy between model established by texture parameters and that by derivative texture indices, select the most effective Xylosma racemosum stand volume estimate model and select the most effective window size. Results indicate that the value of adjusted R2 of fitting models established by derivative texture indices were better than those of texture parameters at the same window size, the value of adjusted R2 of stand volume model could be improved significantly by combination of texture parameters and derivative texture indices at the same window size, the optimal estimation model of Xylosma racemosum stand volume was obtained when all of the texture parameters and derivative texture indices of all window sizes were introduced into stepwise multiple regression, 11×11 was the optimal window size with the largest adjusted R2 for fitting Xylosma racemosum stand volume by texture parameters and derivative texture indices generated at one single window size.

Abstract:Light use efficiency of rice leaves were analyzed using chlorophyll fluorescence spectra in the present research. First of all, photosynthetic rate (net CO2 assimilation rate) of individual leaves and incident photosynthetic active radiation were accessed, and photosynthetic light use efficiency was calculated with them. Meanwhile, laser induced chlorophyll fluorescence emission spectra of leaves of rice under different light use efficiency were measured using a compact fiber-optic fluorosensor with a solid-state laser at 473nm as exciting source and an integrated fiber optic spectrometer at ambient temperature. Then, specific fluorescence spectral bands of leaves were selected to analyze light use efficiency. Significant relations of light use efficiency with F685， F732 and the fluorescence ratio F685/F732 were found, thus indicating functional relations among these parameters. The results show that the precision of the function based on the fluorescence ratio F685/F732 is higher. The assimilation process of CO2 is affected by stomatal conductance and the temperature of leaves is a signature of stomatal conductance. An inverse relation was also found between light use efficiency and temperature of leaves. So measured fluorescence spectra were fitted with a linear combination of regression function corrected by the temperature of leaves to predict light use efficiency，R2=0.885.

Abstract:With the aim to deploy wireless sensor networks and accommodate to application in a peach garden, the frequency of 2.470MHz was selected, a distance of 40m was defined as a reliable communication distance based on the monitoring of variance of packet deliver rate in long term, the result and analysis of short term monitoring of packet delivery rate showed that quality of wireless links changed greatly in short term and there were no significant correlation between them. Then a communication protocol was designed based on the requirement of application and the characteristics of links:with the aim to reduce power consumption of listening ,the flooding time synchronization protocol was improved and flooding-stable root time synchronization protocol was designed; as the link quality changes greatly in short time the collection tree protocol was improved to enhance the packet deliver efficiency, a comparatively complete communication protocol was designed by combining these two protocols above. After that the protocol was implemented with nesC language in TinyOS, finally field tests were carried out in the peach garden, the result shows that the time synchronization errors are less than 10ms in the whole net, the packet delivery rate of communication protocol is 8%~15% higher than that of communication protocol based on MultihopLQI. A TelosB node can run 264d, with the supply power of two AA batteries, indicating that the communication protocol achieves very low power consumption.

Abstract:In order to improve the segmentation accuracy and reduce the segmentation running time of Gaussian mixture model used on wheat lesion images, a segmentation method based on PCA and Gaussian mixture model was proposed. Firstly, in order to completely use the color information of an image, three primary color channels of the image were obtained through the principal component analysis (PCA) method from R, G, B orH, S, Vcolor channels of this image. Secondly, the image was divided into many blocks, which were then sorted according to their mean pixel values. After sorting, those blocks lying in the front and the rear were selected to comprise a new pixel set by the Gaussian mixture model, and further, the corresponding Gaussian model parameters were obtained. Finally, the proposed method traveled all pixels in the image and classified each pixel into the corresponding Gaussian model category. Experimental results show that the proposed method has gained better promotions in segmentation error rate and running time compared with the traditional segmentation method and is effective for wheat leaf rust lesion segmentation.

Abstract:Discrimination of crop’s nitrogen level can contribute to reasonable and effective fertilization. Lettuces of various nitrogen levels were planted in three soilless nutrient solutions of different nitrogen concentrations. In the rosette stage, 84 lettuce leaves of each nitrogen level were collected and scanned by the hyperspectral imaging acquisition system. In every hyperspectral image of lettuce leaf, four different positions of 60×60pixel were selected as regions of interest (ROI). The average spectral data of the ROI were used as the original spectra of the leaf samples. The original spectra were preprocessed by the standard normal variate correction (SNV), and their dimensionalities were reduced through principal component analysis (PCA). ELM algorithm was used to establish model for the training samples, and then was compared with BP algorithm model and SVM algorithm model. The results show that the running time of ELM model is 0.62304s and its classification accuracy rate is 100%. During the same running time, the classification accuracy rate of ELM model is higher than that of SVM model. At the same classification accuracy rate, the running time of ELM model is shorter than that of BP model.

Abstract:The demand for precise positioning manipulators with a large workspace has increased dramatically due to their role in semiconductor manufacturing, medical surgery and automatic micro assembly. In this paper, a planar parallel manipulator (PPM) actuated by three linear ultrasonic motors (LUSMs) for high accuracy positioning is designed. With the aim to realize accurate trajectory tracking control of the proposed 3 PRR PPM, a model and contour error based controller is developedaccording to the dynamic model of the parallel manipulator. The dynamic modeling procedure is as follows: firstly, based on the closed loop constraints of the parallel structure, kinematic analysis of the manipulator is carried out, and the inverse kinematics solution is obtained. Then thevelocities and accelerations of each part, such as rigid linkage, sliders of the motor, and the moving platform, are analyzed in order to derivethe corresponding Jacobian matrices between different coordinates.Finally, the dynamic model of the parallel manipulator is developed using virtual work principle. In a motion trackingtask, it is much more important to minimize the component of the error vector that is the normal with respect to the reference trajectory. This component of the error vector is referred to as the contour error. According to contour error theory, minimizing independent axial errors may not minimize the contour error and conversely, it is possible to have a small contour error while having large axial errors. Hence the contour error based control method is adopted to achieve precise motion tracking in this paper. The contour errorsof three planar degrees of freedom are formulated based on tangential approximation approach, and then a model and contour error based controller is developed using the feedback linearization principle. The stability of the proposed control law is proved based on Lyapunov theory. To guarantee the accuracy of the proposed control algorithm, a kinematic calibration is performed to obtain the real kinematic parameters before the control experiment. The actual position of the moving platform is captured by the CCD camera, and the error cost function is optimized by the particle swarm optimization (PSO) algorithm. Experimental results show that, the trajectory tracking errors of X and Y axes can be reduced to 15μm using the proposed controller, which improves the motion tracking accuracy of the moving platform. The results also present that the tangential approximation approach has the better ability to approximate the real contour error.

Abstract:The hysteresis of giant magnetostrictive actuator has the property of rate dependence. A new model for the rate dependent hysteresis was proposed by using hybrid modeling method. The model is composed of a linearity element and a rate dependent hysteresis element. First, the rate independent hysteresis of the system was modeled by modified PI model when 2Hz sinusoidal signal was employed to excite the system. Second, the coupling response of the linearity and the hysteresis elements was decoupled by the method of combining the inversion of the rate independent hysteresis model and fitting method when 100Hz sinusoidal signal was employed to excite the system. Then, a new rate dependent hysteresis model was proposed and implemented on the above bases. At last, the hybrid rate dependent hysteresis model was obtained by connecting the linearity element and the rate dependent hysteresis element in series. Compared with rate independent hysteresis model and hybrid rate independent hysteresis model, the proposed hybrid model is more accurate than other models.

Abstract:The thermal load and heat transfer performance of heavy vertical lathe rotary table was numerically investigated by adopting fluid solid interaction (FSI) method which makes external boundary conditions into internal. Flow field of air and temperature distributions of workbench, base and hydrostatic oil film were presented in the velocity range of 5~50r/min. The simulation results show that the velocity rising not only causes temperature of oil film increasing significantly, but also causes its carrying capacity decreased. What’s more, the velocity rising strengthens the convection of cooling surfaces and the heat dissipation of base is undervalued above 25r/min, so the temperature of cooling surface is not significantly increased which aggravates heat concentration. FSI method turns the external heat transfer boundary conditions into internal boundary conditions, which makes the simulation more close to actual situation. Meanwhile, numerical simulation results are consistent with the results of infrared thermal imager temperature measurement, which validate the numerical simulation, expand the application domain of FSI method, also lead lathe cooling situation analysis more reliable and accurate.

Abstract:The pose registration between 3D measured data and freeform surface design model is the key to complex surface machining and inspection. In order to realize fast and accurate surface registration, a method based on the maximum entropy principle was proposed. A unified mathematics model was developed based on the analyses of machining localization and the registration problem of quality evaluation of parts. The efficient numerical algorithm for the unified model was researched. Based on the maximum entropy principle, the registration problem established on the min max criterion was converted to a perturbed problem with the entropy function as the perturbation. As a result, the non differentiable object function is perfectly substituted with the maximum entropy function. This provides a possibility to improve the efficiency of solving registration problems. Experimental results about the allowance distribution and the error inspection show the validity and practicability of the method.

Abstract:Three commonly used two equation turbulence models were adopted. The computed velocity field was compared with the data from corresponding laser Doppler anemometer measurement to analyze the accuracy of these models. By adjusting the model parameters, the simulation data can fit into the experimental result. The optimal viscosity coefficients Cμin these used eddy viscosity models were presented. It is shown that the RNG k-ε model is more sensitive to Cμ, while the results from Standard k-ε model vary almost linearly with the change of the Cμ value. Study on the simulated flow field gives that if the peak of turbulence kinetic energy appears within the radial span, it will affect the velocity distribution along the jet axis; otherwise, it will modify the velocity magnitude. The proposed numerical scheme reduces the physical complexities involved in ultra high pressure injection process so that it can be applied to archive fast production from relevant CAE workflow.

Abstract:Based on theoretical modeling, dynamic test and multi objective optimization technique, a parameter identification method of generalized joints was proposed. The method first considered the double coupling characteristics between joints and machine tool parts, and then constructed the generalized equivalent joint model of linear guideway. By structure condensation technique, more accuracy and higher efficiency of computation were achieved. Finally, the whole structure dynamic model in impedance form under constraint condition was derived. This model combines the theoretical modeling, dynamic test and multi objective optimization problem to identify the joints parameters based on transfer function and impedance information acquisition. The verification examples show that this identification method is effective, the errors of modal frequency and frequency response function are very small, and the identification accuracy is high.

Abstract:A double stator symmetrical type multi pump and multi speed motor is designed based on the principles of existing symmetrical constant pumps and constant motors. In the shell, a rotor is corresponding to two stators, so the multi speed motor can work independently and synchronously. As an example, we describe the structure and working principle of the double acting symmetrical type double stator multi speed motor, define its symbolic representation method, and analyze the output flow features of the multi pump and the output speed and torque features of the multi speed motor. The speed of the multi speed motor under different combinations of multi pump and multi speed motor is analyzed. The results show symmetric type double stator multi speed motor can output many different speeds and torques. The study establishes a basis for applications of double stator multi pump and multi speed motor system on machine tools, mobile machineries and so on.

Abstract:Based on the principle of ultrasonic transmission method with some hypothesis, a relationship model between porosity, the number of layers and the ultrasonic attenuation was established for different CFRP laminates. Firstly, under several assumed conditions, a relationship model between the number of layers and the ultrasonic attenuation was established without porosity. This model can reflect effect of other factors on the ultrasonic attenuation. Then, considering the effect of voids, the model was improved with the factor of porosity. Finally, using the test data of the porosity and ultrasonic attenuation for 5 different laminate test blocks, a fitting porosity mode was given. The analysis and test result show the model has enough precision and can certify the requirement of engineering test. This model can be used to test the porosity of different composite laminates in same bath and doesnt need to prepare too many samples, so it is convenient and fast, as well as cost saving. On the basis, a relationship model between porosity, thickness and ultrasonic attenuation was established by revising the porosity model. As for composites with variable thickness, it is needed to replace the number of layers by thickness. Whats more, refraction phenomenon may occur while the ultrasound propagates at the back wall. So other factors should be revised. The analysis shows that, the included angle between the propagation direction and the normal direction of back wall plays an important part in the model. And the attention will increase rapidly with the angle increases. So the model is suitable for the composites with big curvature radiuses.

Abstract:he hot platen needs to be lifted and descended integrally, and to be kept in horizontal level during the process which was realized by position synchronization control of multiple group hydraulic cylinders. It is a difficult point in control of continuous flat press. In order to solve this problem, a ramp type successive approximation algorithm was proposed. The algorithm can dynamically select one group of hydraulic cylinder as “virtual main system”, and the other groups as “slave system” according to the actual displacement of the hydraulic cylinders in any control cycle. Then the virtual main system can gradually approach the target value step by step with a certain ramp. At the same time the slave system tracks the virtual main system in real time, so that it can be realized that the multiple group hydraulic cylinders move synchronously during the lifting and descending process. The algorithm was simulated in Matlab. Then the algorithm was applied to the continuous flat press production line designed by China Foma (Group)Co., Ltd. Production practice indicates that the algorithm can solve the interaction and influence between the multiple group hydraulic cylinders in movement effectively. The synchronous error of the lifting and descending process is 0.5mm and 0.6mm respectively. The shock of hydraulic components is less, the process is smooth and the control precision can meet technological requirements.

Abstract:Flooding diagnosis is the key issue of PEM fuel cell. Flooding prediction through hydrogen pressure drop is investigated in this study on a two piece PEMFC stack. Pressure drop is a key parameter to diagnose water content of PEM fuel cell. The hydrogen pressure drop is more suitable for flooding prediction because it can reflect not only the content but also the water harm on PEM fuel cell. Furthermore, the ideal hydrogen pressure drop is calculated through the operation conditions. Flooding experiments are organized and a two level characteristic on hydrogen pressure drop is observed. At first, the actual hydrogen pressure drop keeps steady nearly the same as the ideal value, and the voltage is pretty high and constant. Next, the hydrogen pressure drop rises gradually because of the appearance of water droplets. Then, the hydrogen pressure drop performs the second steady level because the water droplets form a liquid film. Finally, the hydrogen pressure drop rises quickly and the voltage drops rapidly as the formation of slug flow. Combining with the visualization results of water droplet accumulation in channels and the tendency of hydrogen pressure drop and voltage, the flooding process can be divided into four continuous periods, which are proper period, humid period, transitional period and flooding period. The growth rate of the hydrogen pressure drop is defined and four groups of flooding experiments are completed, in which the effects of current, temperature, pressure and hydrogen stoichiometry can be discussed. Experiment results show that current and temperature influence little on the growth rate of two levels, while the effect of pressure and hydrogen stoichiometry is remarkable. Increasing the gas pressure can improve the ability for anti flooding in PEMFC, increasing the hydrogen stoichiometry will waste hydrogen as consideration. The hydrogen purge can take a part for a while in the flooding period to prevent the fuel cell from falling into total flooding, while it does not change the operation conditions which lead to flooding. The hydrogen pressure drop should be controlled before the transitional period. The moist section can be planned out in the first half of the humid period based on hydrogen pressure drop. In the moist section, PEM fuel cell is supposed to be far from the occurrence of flooding. Adjusting the fuel cell stack working temperature may be an effective method to realize the flooding prediction.