Abstract:A hydrogen fueled constant volume combustion simulation apparatus was designed. By means of Schlieren method, combustion characteristics of hydrogen-air pre-mixture were studied in the apparatus on the condition of no adaptor and built-in one. The result showed that it was able to simulate the auto-ignition of the pre-mixture. Under the experimental conditions, there was a jet of flames on both sides of the spherical flame respectively in the test with no adaptor; the auto-ignition of unburned gas appeared firstly in the angle between the spherical flame front and the chamber wall. In the test with built-in adaptor, it could achieve auto-ignition through both plans. The second plan can effectively prevent the flame propagation from the upper chamber to the lower one, and the unburned gas was auto-ignited.

Abstract:A novel double eigen angle-based steady-state flow test rig to comprehensively investigate port generated air flow inside a 4-valve EFI gasoline engine cylinder head was developed. The concept of eigenvector was introduced and the eigenvector path of the in-cylinder tumble flow was protracted; besides, the eigenvector table under different valve lifts in the dummy cylinder was shown to get a macroscopical reflection of the intensity, the tested plane, the vector direction and the distribution of the inclined swirl. In the process of the optimizing the intake system of the engine, a new methodology and comprehensive data basis were provided to organize the optimization the regional and the strength of the appropriate in-cylinder air movement, and improve the performance of the engine.

Abstract:The influences of intake flow on spray and wall-film were studied by using numerical simulation and test-bed experiment. Some results were received and they showed that the intake flow was useful for liquid fuel evaporation before impinged on the wall and could increases the spay penetration and deflect the spray in the direction of the intake flow. Meanwhile, the momentum of the spray droplets was strengthened and more small droplets could be received by the intake air flow which can enlarge the wall-film area and improve the evaporation of wall-film. If the engine body temperature was low, the effect of intake flow on engine performance was obvious while it had no difference under wide throttle open angle for high engine temperature.

Abstract:A 3-D combustion model considered the characteristics of Jatropha curcas oil was established, the combustion process of diesel engine fueled with Jatropha curcas oil was simulated. Simulation results of the cylinder pressure fitted well with the results of test. The flow field, temperature field, and mean temperature in cylinder were analyzed by the simulation. It is found that the injection timing is advanced when the engine fueled with Jatropha curcas oil. The timing of combustion is advanced, the peak premixed combustion is also advanced, and the combustion duration is longer than the engine fueled with diesel fuel.

Abstract:A dual diesel particulate filter system was developed by using the heat resistant filter bag as filtering element. The intake fresh air of the diesel engine was used to blow off the deposited particulate matters (PM) and send them back to the cylinder. The blow-off PM in the filter was assisted by high-pressure air scanning reverse flow. The PM burning in the cylinder realized the regeneration of the filter. The verification tests were performed in the dynamometer test bed with a single-cylinder diesel engine. Under the steady operating condition, and the filtering time span was equaled to the regeneration time span, the resistance of intake and exhaust of bag-type-filter rehabilitated thoroughly. It showed that the intake process of the intake fresh air and high-pressure air could blow off the deposited PM on the outer surface of the bag, ensure the successful regeneration of the bag-type-filter with filtering efficiency of 82%～94%.

Abstract:In order to study the heat and power conversion efficiency of diesel engine with different coolant temperatures, an engine and cooling system co-simulation model was built based on the first law of thermodynamics. This model was established by GT—Suite software to simulate the interaction of engine and cooling system performance parameters. A heat balance experiment of DEUTZ TCD8V2015 diesel engine was designed and executed, and the model was verified by the experimental data. Based on that, the coolant temperature influence of conversion efficiency was researched on the modified model, some rules and tends between the coolant temperature and the heat transfer in the cylinder were obtained. Results indicated that the power conversion efficiency would increase by 2%~3% with coolant temperature raised by 20℃ on 30% load of diesel engine.

Abstract:Wastewater irrigation test under biological swimming bed and biological filter was done to study biofilm growth situation in emitters. Results showed that biofilm growth experienced three periods of attachment period, growth period and maturity period, and biofilm was at a dynamic equilibrium state in maturity period. Biofilm was attached fast, growth fast and was the thickest on the inlet of emitters. Detached biofilm deposited on the inside flow or the outlet, which was embodied on the flow changes. The average flow changes of emitter lagged growth change of biofilom. When biofilm reached maturity period, it was detached repeatedly to grow, and this was high-risk period of emitter clogging when the average flow of emitter was declining. After 184h, acid and chlorine can be added to flush emitter.

Abstract:In order to better understand the causes and the processes of clogging for labyrinth-path emitters, the influences of sediment concentration, sediment particle size distribution and water temperature on emitter clogging were investigated through the intermittent drip irrigation method. The result showed that smaller particles tended to cause emitter be clogged during the irrigation when the particle sized in muddy water were less than 0.1mm, and the degree of clogging increased remarkably as sediment concentrations increased. The degree of emitter clogging was also impacted by water temperature. Emitters were less likely clogged by muddy water with higher temperature. It was found that in the summer when water temperature was relatively high labyrinth-path emitters were prone to clogging by sediment with particle sizes below 0.031mm.

Abstract:With the aim to raise measure accuracy of double-depth measuring water content tactics in precision irrigation control system, by integration research of water content sensor, dual-layer composite soil water content sensor was worked out. Compared with the traditional two sensors’ tactics, using dual-layer composite soil water content sensor, the measurement result can be more accurate, and energy consumption was reduced. In order to achieve optimal irrigation amount of green land plant, ensure the irrigation not be wasted and satisfy plant’s normal need, the experiments were carried out by taking tall fescue for an example. On the basis of aggregately analyzing the tall fescue’s growth requirement, soil water content and parts of meteorological dates, the result was gained, that is the optimal irrigation amount of tall fescue is 12mm.

Abstract:The factors that have obvious effects on spatial variability at the different scales were identified with joint multifractal, and pedotransfer functions of van Genuchten model parameters which considered scale effect at small and large scale were established based on the above educed conclusion, furthermore, feasibility that concluded and educed at small scale with joint multifractal and applied at large scale was explored. The results showed that root mean square error of forecasted soil water content based on pedotransfer functions of van Genuchten model parameters in 0~20cm and 20~40cm soil layers at small scale was 0.0386 and 0.0473 respectively, and RMSE of forecasted soil water content based on pedotransfer functions of van Genuchten model parameters in 0~20cm and 20~40cm soil layers at large scale was 0.0270 and 0.0304 respectively; conclusions educed at small scale with joint multifractal could be applied at large scale, and pedotransfer functions based on these conclusions had strong theoretical foundation and high precision.

Abstract:Various particle-size fractions of soil aggregates were obtained with the wet-screening method from the soil of a long-term stationary fertilization experimental field of Beijing Yanqing Lvfulong organic vegetables farms to analyze the effect of microbial communities on carbon distribution in brown soil aggregates under different fertilizations with sequence analysis by 16SrDNA-PCR-DGGE technology. Results showed that with different fertilization treatments, treatments OF(organic fertilizer) increased 0.25~2mm water stable aggregates by 109.0%; compared to CK (unfertilized), 0.053~0.25mm and 0~0.053mm particle aggregates decreased by 31.9% and 142.1%, respectively. Treatments OF significantly increased carbon content in aggregates of all particle sizes by 15.2%~46.9% compared to CK, and in the >2mm aggregates by 46.9%. The content of brown soil carbon was positively related to the content of the >2mm aggregates; significantly positive related to the content of the 0.25~2mm aggregates, but significantly negative related to the content of the 0.053~0.25mm aggregates; negative related to the content of the 0~0.053mm aggregates.

Abstract:With the aim to solve the problem of shape distortion when generating the finite element mesh of parametric surfaces, mapping method was used. But mapping method could generate distortion elements which lead to poor quality meshes easily. Based on the Riemannian metric, a combined advancing front technique (AFT) and Delaunay triangulation（DT） method were applied. In this algorithm, Riemannian metric was considered, and background grids of parametric space were generated by improved AFT. When background grids of parametric space were refined to counteract mapping distortion, the traditional Delaunay incremental insertion kernel was replaced by inserting the center of triangle circumscribed ellipse, and the algorithm for locating ellipse center and judging whether nodes within ellipse. The mapping distortion and algorithm efficiency were considered by the algorithm by introducing Riemannian metric and reasonable background mesh. Examples show that the new method is easy to implement. The mesh which has good stability and high quality can be generated.

Abstract:In order to study internal flow variation when centrifugal pump cavitations occur, three-dimensional modeling was used for centrifugal pumps internal flow through three-dimensional software Pro/E. Based on the Reynolds-averaged N—S equations with the RNG k—εturbulence model and SIMPLEC algorithm, the full-cavitation model was used considering effects on cavitations when the gas was not dissolved in the water. By using the computational fluid dynamics software CFX, the numerical simulation calculation of vapor-liquid two-phase turbulence within whole flow passage of centrifugal pump was conducted and the laws of the unsteady flow when centrifugal pump cavitations occur were analyzed. The results show that within this range from the newborn to the critical cavitations NPSH, the gas volume fraction mainly begins from dimensionless radial position 0.2, and the gas volume fraction density correspondingly increases with the lower of NPSH. Affected by asymmetry distribution under the effect of the impeller and volute coupling, in the newborn of cavitations, impeller pressure fluctuations were sinusoidal periodic variation. With the lower of NPSH and gas volume fraction increasing, impeller pressure is changing irregularly. From the beginning of the tongue, along the impeller rotating direction, pressure fluctuation gradually declines.

Abstract:The flow in end wall region of axial-flow impeller has an important impact on flow structure, energy transfer and hydraulic efficiency. The hydraulic axial-flow pump models with different tip clearance sizes were simulated based on CFD technology and high-quality structured grid. The influence of tip clearance on the meridional velocity and circulation distributions in impeller inlet and outlet were discussed, and the leakage vortex generation mechanism and its structure were analyzed as well. The numerical results were compared with high-speed photography experimental results. The investigation results showed that tip clearance led to non-uniform meridional velocity distribution in impeller inlet and secondary flow in end wall region occurred, meridional velocity near tip clearance in impeller outlet decreased, and the bigger the gap was, the bigger decline of meridional velocity would be. The secondary recirculation near the wheel led to circulation of impeller inlet, when the gap increased to 2mm, about 50% of the whole flow passage appeared circulation which impacted by the tip leakage vortex. The trajectory and structure of tip leakage vortex in the numerical simulation showed agreement with the experimental results. Under the small flow rate conditions, the leakage vortex strength and the influence regional scale were increased.

Abstract:For a typical 150QJ20 type deep-well centrifugal pump, three positions of the impeller inlet edge were designed. The whole flow field of the deep-well centrifugal pump was simulated with Fluent code based on standard k—εturbulence model and the SIMPLEC arithmetic. The static pressure and turbulent flow field were compared, the impact of the position of impeller inlet edge on the hydraulic performance was analyzed. The results showed that appropriate extend the impeller inlet edge could reduce the turbulence intensity of impeller exports and improve the flow field, also could reduce the impeller inlet diameter and increase the hydraulic performance of deep-well centrifugal pump.

Abstract:In order to research pressure fluctuation of unsteady flow in screw-type centrifugal pump with small blade, three-dimensional unsteady flow field of the pump was simulated numerically to the screw-type centrifugal pump with and without small blade based on Navier—Stokes equations and k-εturbulent model. Pressure fluctuations in the outlet of pump and in the volute were obtained at different flow rates. The analysis results indicated that the pressure wave in the pump was always periodic in the two models, and impeller blade passing frequency was the dominant frequency. Compared with the result of single blade at different flow rates, the period decreased to half, and the amplitudes of pressure fluctuations in the pump was smaller, the high-frequency components were also fewer. The analysis results indicate that the adding of small blade in impeller of screw-type centrifugal pump with single blade can not only decrease the pressure fluctuation of unsteady flow in the pump, but also decrease oscillations in volute.

Abstract:In the cold PIV (particle image velocimetry) system of the laminar entrained flow reactor, the relative position between the camera and the measuring tube was an important condition to ensure accurate test data. To make the PIV operation more convenient, accurate, and fast in the test, two-dimensional PIV automatic control system was designed. And the reliability of the system was tested in the cold simulation equipment of laminar flow furnace, compared with no using two-dimensional PIV automatic control system, the results showed that in different sections of the measuring tube, the particle speed of the axial center achieves a smooth transition, and eliminates the jump change; when collection distance is 350mm and main air flow rate is 1.5m3/h, the relative error of particle residence time is 9.218%; and the operation saves time and effort in the test process. These suggested that the two-dimensional PIV automatic control system could satisfy the cold test of the laminar entrained flow reactor needs, achieve uniform and continuous test, reduce human error and improve the accuracy of test data.

Abstract:Two layers of air distribution were designed to actively control the agent feed in down-draft fixed bed biomass gasifier. The pressure and velocity distribution inside the gasifier were studied by simulation analysis. The pressure field displayed the law of step distribution and obvious boundaries. The velocity pattern was higher from top to down with high level of uniformity in the same section. Experiments were done to test the pressure and temperature distribution in the gasifier by using corn stalk as materials. The results showed that it had an important effect of active air distribution on promoting the reaction uniformity. The temperature kept stability at the same section with little changes of the gas components, and calorific value kept above 5 500kJ/m3.This method can provide a new way to improve the working performance of the fixed gasifier.

Abstract:The correlation between six electrical parameters such as impedance and twelve physiological parameters such as firmness of fruits were analyzed in order to study the relationship between electric properties and physiological properties of “Qinmei” kiwifruit stored at room temperature (20℃) and to explore the feasibility of nondestructive testing of physiological characteristics by using electric parameters. The results showed that Z can quantify eight physiological parameters such as firmness of fruits, Cp can quantify seven physiological parameters, inductance (Lp) can not quantify any physical parameters. The correlation between impedance angle (θ) and physical parameters (TA content, relative electrical conductivity, starch content, cellulose content and Xyl activity) was generally high at twenty-four frequencies, so it is reliable to useθto quantize above physiological indexes. All physiological parameters can be quantified by sensitive electrical parameters except amylase activity, PE activity, PG activity and Cx activity.

Abstract:Dried distillers’ grains were rich in nutrition, which used as protein feed materials, and could give some benefit to supplement feed deficit and reduce feed cost. Totally 78 dried distillers’ grains samples were collected from 21 provinces of China. Crude fiber, crude ash and crude protein contents were detected in laboratory by standard methods. The statistic analysis showed that the distribution range of crude fiber, crude ash and crude protein contents were 1.60%~37.54%, 0.74%~26.85% and 12.01%~38.69%, respectively, the standard distribution value of them were 8.33%, 5.21% and 7.11%, respectively. The big differences in components content were mainly caused by the remaining rice hull during drying and separating process. Quantitative evaluation models were established to determinate crude fiber, crude ash and crude protein content of dried distillers’ grains by NIRS methods. The results of NIRS analysis showed that this method could provide rapidly quantitative prediction for crude fiber, crude ash and crude protein contents in dried distillers’ grains, the coefficient of determination in calibration were 0.98, 0.91 and 0.96, respectively; the standard error in calibration were 1.19%, 1.58% and 1.61%, respectively; the coefficient of determination in validation were 0.98, 0.92 and 0.96, respectively; the standard error in validation were 1.20%, 1.57% and 1.60%, respectively, and the ratio of performance to standard deviation were 7.38, 3.75 and 4.98, respectively. The prediction values of these models are accurate.

Abstract:Totally 180 samples coming from one orchard were divided into calibration set with 150 samples and prediction set with 30 samples. Field Spec3 spectrometer was used for collecting spectra data of 180 fresh jujube samples separately. Then successive projection algorithm and stepwise regression analysis combined with spectral theory were used to process the spectral data after MSC pretreatment. Characteristic wavelengths of 150 samples in calibration set were selected by using SPA and SRA, and the partial least square (PLS) and LS—SVM methods were used to establish models of the fresh jujube soluble solids with the whole spectrum and characteristic wavelengths selected by using SPA and SRA. At last, the models of MSC—PLS model, MSC—LS—SVM model, the MSC—SPA—PLS model, the MSC—SPA—LS—SVM model, the MSC—SRA—PLS model and the MSC—SRA—LS—SVM model were used to predict the soluble solids of 30 samples in the prediction set. The results showed that the correlation coefficient and the root mean square error of prediction of MSC—PLS model for full band are 0.8874 and 1.0889 and that is the best. The correlation coefficient and the root mean square error of prediction of MSC—SPA—PLS model and MSC—SRA—PLS model are 0.7990, 1.4078 and 0.8224, 1.3851, and they are less precise than the MSC—PLS model. The correlation coefficient and the root mean square error of prediction of MSC—SPA—LS—SVM model are 0.7963 and 1.1458, and that is more precise than the MSC—LS—SVM model. The precision of MSC—SRA—LS—SVM model is very low and is not suitable.

Abstract:Pearl barley was used to study the influence of frequency (1~1000kHz), temperature (5~40℃) and moisture content (14.7%~22.7%) on the relative dielectric constant. The reasons for dielectric constant changed with these factors were analyzed. Furthermore, the mathematical model for predicating moisture content of pearl barley based on the dielectric constant and temperature at 100kHz was established, and the model was verified. The results indicated that the dielectric constant of pearl barley increased as moisture content and temperature increasing, decreased with frequency increasing over the frequency range from 1~1000kHz. The relationship between the dielectric constant, temperature and moisture content can be described by cubic polynomial, with the coefficient of determination of 0.9976 at 100kHz. Obvious linear relationship was observed between measured moisture contents and calculated moisture contents, with coefficient of determination of 0.9977.

Abstract:The viscosity, swelling degree, water retention and gelatin textural properties of inulin were explored. When the inulin content was lower than 25%, the viscosity of aqueous solution was low and the increasing was not significant with the content increasing. However, with further increasing in the content, the viscosity increased rapidly. Temperature had significant effects on the swelling degree and the water retention, both of them had the same trend and reached the maximum value at 40℃. The gelling ability of inulin was evaluated by using gel index (VGI) and gelling time. The results showed that inulin could not gelatinize completely unless the content was no less than 35% and the gelling time became shorter as inulin content increased. TPA test showed that hardness, gel strength, adhesiveness, adhesive force and gumminess of gel were improved in the different extents as inulin content increased and storage time prolonged. Hardness, gel strength, adhesiveness and gumminess of gel were improved significantly when the inulin content was above 40%.

Abstract:Fifty Pu-erh tea samples were investigated for acrylamide (AA) contents. The results showed that the AA contents in tea samples were generally low, 2.05～91.95ng/g. Based on the correlation analysis between sugar contents and the amount of AA，it was found there was the highest correlation coefficient between the sucrose content and AA (R2=0.5776), followed by fructose (R2=0.4977), glucose was the least (R2=0.2567). The asparagine contents of wet-stored Pu-erh tea samples could not detected. In combination with literature records, it could be concluded that AA mainly generated through acrolein way during the fermentation of Pu-erh tea. There was a very small contribution of asparagine way.

Abstract:Chardonnay dry white wines from main wine producing districts in China were collected to analyze aroma quality and reveal the mathematic relations between aroma characters and volatiles. Sensory analysis was made by 30 panelists who were trained by using “Le Nez du Vin” wine aroma kit. The sensory data were composed of intensity and by using frequency of characters. SPME—GC—MS was used to identify and quantify aroma compounds in wine. PCA and correlation analysis of sensory data showed six typical aroma characters of the Chinese Chardonnay dry white wines: citric, pineapple, violet, lime, green apple and lemon. Odor active value (OAV) analysis indicated that 25 ones of 64 aroma compounds quantified in sample wines were impact odorants. Six regressive models of typical characters were built by aroma compounds to predict typical aroma intensity. Aroma quality and wine origin could also be estimated by the models. Five models have significance at 0.01 levels on ANOAV. Coefficients and constants of models are also significant at 0.01 level, and the correlation coefficients between the measured and predicted values （R2） are between 0.979 and 0.999. Chinese Chardonnay dry white wines from main producing districts have typical aroma characters. Aroma characters and volatile compounds have obvious relative relations, and some aroma compounds could be used to predict wine aroma characters.

Abstract:The effects of drying temperature, material load and airflow rate on hot-air drying characteristics of the moisture content and dehydrating rate of ginkgo fruit were investigated by applying self-made hot-air drying online testing device. Drying temperature, material load and airflow rate were the influence factors, and moisture content, dehydration rate, average energy consumption of drying process, protein retention rate and sensory quality of dried ginkgo were the experimental indices, and the relationships between the experimental indices and the influence factors were analyzed through the responsesurface analysis method and sub-stepping method. The quadratic regression mathematical models that described the relations between the experimental indices and the influence factors were established. The optimal combination of technological parameters for drying materials was obtained through conducting a multi-objective function optimization by function expected optimization. The hot air drying process of ginkgo is mainly concentrated in constant-speed phase and decelerated phase, and the optimal parameters are as follows: hot-air temperature of 68℃, airflow rate of 1.15m/s, and material load of 15.58kg/m2.Under these conditions, the energy consumption is 11.86kW·h/kg, the dehydration rate is 9.77%/h, protein retention rate is 90.30% and the sensory score is 8.57. The results can provide a theoretical basis for drying and industrialized production of ginkgo fruit.

Abstract:The possibility of using two-stage ultrafiltration technique to separate ovalbumin and lysozyme from chicken egg white was investigated. Based on the mechanism of ultrafiltration, main factors that affecting the permeate flux and total proteins concentration in permeating liquor, such as initial feed concentration, pH value and transmembrane pressure (TMP) were studied. After ascertaining the ultrafiltration time by examining the change of permeate flux, the optimum ultrafiltration conditions were supposed to be as the follows: initial feed concentration, 6.0%; pH value, 2.5; TMP, 0.12MPa. In these optimum conditions, purity and yield of ovalbumin was 85.72% and 51.36% respectively, and that of lysozyme was 87.21% and 62.58% respectively, implying that separation efficiency was satisfied. The experimental results show that it is feasible for two-stage ultrafiltration technique to separate ovalbumin and lysozyme from chicken egg white in bulk and high efficiently.

Abstract:In order to avoid obstacles for fruit harvesting robot, the method of spatial information extraction of tree branch was studied. The method of normalized cross-correlation was used to get the disparity map of stereo image, branch skeleton was extracted and feature points were extracted by multi-segment approximation method. The spatial coordinates of branch feature points were calculated by combining with the disparity map based on binocular stereo vision, the radius of branch feature points were calculated by using the branch range image, in the end, the forked branch was divided into separate section. Rapid model reconstruction for fruit tree was researched: firstly, each branch module was constructed by 12-prism in the coordinate origin; then, every module was set to the correct posture by affine transformation; finally, the complete fruit tree model was restructured. Experiments show that the virtual trees provide the actual environment reference for obstacle avoidance and path planning of fruit picking machine.

Abstract:In order to improve the recognition accuracy, a method of overlapping tomatoes recognition based on curvature analysis of edge points was presented. Edges of tomatoes were extracted from binary image at first. Then curvature values could be acquired after edge points were sorted counterclockwise. The edge points with abnormal curvature values were abandoned. After circle regression for remaining edges, overlapping tomatoes could be recognized. In order to decrease the negative impact on recognition aroused from environmental lighting variation and occlusion caused by leaves and branches, threshold segmentation method based on normalization aberration, 6 rules for edge recognition and 3 rules for circle regression were adopted. The experimental results of 119 images showed that the recognition accuracy for overlapping tomatoes with slight occlusion was 90.9%, it was 76.9% when the occlusion rate was between 25% and 50%, and it was 23% when the occlusion rate was larger than 50%.

Abstract:Pulse coupled neural network (PCNN) and mathematical morphological technologies were employed to separate the mature in-greenhouse cucumber from complex background image. Four geometric feature values and three texture feature values based on gray level co-occurrence matrix (GLCM) of every connected regions in image were extracted, which were the input feature vector of least squares support vector machine (LS—SVM). The trained classifier was used for identifying the cucumber in image. Experimental results showed that 70 cucumber images were used for testing, the average rate of correct identification reach to 82.9% in different conditions, indicating that the method based on PCNN and LS—SVM could be used for in-greenhouse cucumber recognition.

Abstract:A feature extraction and identification method of corn haploid and hybrid kernels was studied. The corn kernels were produced by hybrid induction after importing gene markers to their male parent in corn haploid breeding process. The proposed method made the accurate identification of corn haploid kernels come true. Corn kernels produced by hybrid induction was researched. Firstly, the corn kernels were divided into three parts according to the color distribution, including purple marks, yellow endosperm and white embryo. Then a (G-B)R/B model was proposed by analyzing color features of pixel samples that got from the three parts. This model could extract the purple marks area effectively. A simple and quick identification method of corn haploid kernels was proposed after researching on morphological characteristics of corn kernels and distribution characteristics of purple marks. Experiments finished in the corn haploid sorting platform, they showed the accurate rate of corn haploid identification was above 98.07% by the proposed method, and it met the requirements of dynamic test.

Abstract:By field trials, the canopy hyperspectral reflectance and percentage vegetation cover (PVC) for winter wheat during 2010 and 2011 growth periods were measured. The canopy spectral characteristic of different PVC and the relationship between canopy reflectance and PVC were analyzed in different growth periods. The winter wheat PVC estimation models based on normalized difference vegetation index (NDVI), ratio vegetation index (RVI), wavelet energy coefficients were established in different growth periods. The results showed that the spectral reflectance of winter wheat decreased in visible bands, however, increased in near infrared bands following the PVC increased. The spectral reflectance was negatively correlated with the PVC in visible bands, but the correlation coefficient turned to positive correlation near the red edge. The PVC estimation models based on NDVI was performed better at the regreening stage and elongation stage with determination of coefficient (R2) 0.8359 and 0.8057, respectively. However, the PVC estimation models based on RVI was better at the heading stage, filling stage with R2 0.8031 and 0.8294, respectively.R2 of the PVC estimation models based on high frequency energy coefficient and low frequency energy coefficient were 0.9112, 0.8954, 0.8802, and 0.9275 at the regreening stage, elongation stage, heading stage and filling stage, respectively.

Abstract:A precise light compensating method integrated with real-time environmental monitoring, specific wavelength light complementing and quantitative decisionmaking was proposed. Based on feedback control mechanism, a quantitative decision-making algorithm was put forward. Using a single chip as the central control unit, the light complementing value was accurately calculated based on the environmental temperature and the difference between target and real-time values of light intensity of red and blue light. Light intensity output of LED was adjusted by PWM duty cycle to meet the demand of light complementing. Experimental results show that the system has achieved quantitative multi-waveband light complementing. And it realized the energy saving of 54% and 83% respectively to filament lamp and fluorescent. With the same LED, the system has an average energy saving ability of 30% or more compared to the existed LED light compensating system, and the energy saving rate fluctuated at different light quality thresholds and environment conditions.

Abstract:The random search strategy was substituted by the chaotic traveling strategy in standard simulated annealing algorithm, variance evaluation criteria was appended as a condition to stop searching, a special method was adopted to determine the initial temperature in order to reduce redundant iterations, the improved stimulated annealing algorithm was applied to minimize the total power consumption of the multiple chiller water units which connected in parallel to achieve the purpose of energy saving. The mathematical model of the multiple chiller water units and the energy-saving methods by means of the improved simulated annealing were established. Both the theoretical analysis and the actual results indicated that the energy savings could be realized, and the total energy consumption of all the chillers was reduced by 4% to 11% compared with the usual load distribution strategy.

Abstract:In order to solve reconfiguration and optimal scheduling problems of networked collaborative manufacturing resource, a multiobjective optimization mathematical model was provided with four practical important objectives were considered simultaneously, including minimizing the total production working hours, total production working cost, optimization total production processing quality and resource service quality. A reconfiguration and optimal scheduling method for networked collaborative manufacturing resource was presented based on Pareto multi-objective immune genetic algorithm. In order to ensure the groups variety, prevent the premature convergence problem, some key technologies such as population ranking technique, niche technique, Pareto solution set filter were applied. The genetic operators were improved and self-adaptive crossover and mutation operators were proposed by the algorithm, and immune selection could eliminate semblable individuals. Immune memory was adopted to dynamic search near each approximate optimal solution, so it accelerated search and improved quality of solution. Finally the result of simulation indicated the validity of algorithm.

Abstract:Kinematics based on parallel mechanism of a new bionic-mobile robot with six legs were studied, and the method of coordinate transformation was used to construct kinematic model for parallel mechanism of the bionic-mobile robot; the geometrical relationship among the ends of different branches was applied to solve forward kinematics for the parallel mechanism, and the results of simulation indicate that construction of the kinematic model is right, solution of the forward kinematics is right; geometric modeling and numerical solution can be used to solve the inverse kinematics for parallel mechanism of the bionic-mobile robot and the existences of inverse kinematics for the parallel mechanism was testified.

Abstract:Spatial parallel mechanism of a novel 4—SPS/CU that can perform three-dimensional rotations and translation about Z axis was presented. The parallel mechanism of 4—SPS/CU, with SPS-limp regarded as the driver and CU-limp regarded as the driven, was synthesized. The principles that the mechanism could perform the above motions were analyzed based on the screw theory, and the degree of freedom of the mechanism was calculated. The forward and reverse solutions of position analysis were presented, then the Jacobian matrix of the mechanism was derived and its velocity, acceleration performance, singular configuration and workspace were analyzed.

Abstract:In order to improve dynamic characteristics of high-speed spatial PCMM (parallel coordinate measuring machine), the virtual prototype technology was applied to the elastodynamics optimization design of PCMM. Integrating CAD, CAE and visual technologies, the rigid-flexible virtual prototyping of PCMM was built. The influence law of the mass of moving platform and the diameter of driving limbs on the dynamic behaviors, including kinematics output response and maximum dynamic stress of driving limbs were discussed. On these grounds, the mass of moving platform and the diameter of driving limbs were optimized. The optimal results, which include the mass of moving platform of 80.85kg and the diameter of driving limbs of 44mm, were obtained. The simulation results showed the maximum dynamic stress of driving limbs were decreased to 17.5MPa, the kinematics output response were also reduced, so that the obvious improvement of the dynamics characteristics for PCMM was realized, and the powerful theoretical basis and method were provided.

Abstract:Aimed at achieving real-time evaluation on 3-D surface which is difficult due to the large number of surface information and high computational complexity, a GPU-based fast evaluation method was investigated. Rapid surface quality evaluation was realized by the GPU-based fast evaluation method developed by CUDA. The experimental results indicate that the method can significantly improve the calculation efficiency while ensuring the accuracy. It can meet the requirements of online assessment on 3-D surface quality.

Abstract:Take magnesium alloy car’s wheel hub as the investigated subject, and based on the advanced technology of magnesium alloy car’s isothermal spinning shaping, the equipment of spinning shaping was developed. The continuous and partial plastic deformation process of wheel hub radials were numerically simulated through finite element method, and deformation regulations were also analyzed and process parameters were optimized by orthogonal tests. The results of the experiments showed that this new technology significantly increased the size of continuous deformation zone, made deformation paths reasonable, and greatly improved shaping efficiency and machining accuracy.

Abstract:In order to perfect the theory on the cyclical slit flow of concentricity, the distribution features of the cyclical slit flow were analyzed from stopping to starting and to run procedure on the cylinder by a combination of theoretical analysis and model experiments. It is concluded that the speeds of the cylinders, the gap widths and the discharges have effect on the distribution and magnitude of the cyclical slit flow. The cyclical slit flow velocity increased firstly and then decreased as the gap width enlarged. When the gap width was about 2cm, the cyclical slit flow velocity reached a maximum. The larger the discharge was, the larger the cyclical slit flow velocity would be. The larger the speed of the cylinder was, the larger the cyclical slit flow velocity would be. The cyclical slit flow rate increased to the maximum before the speed of the cylinder, the cyclical slit flow rate and the water velocity in the pipe intersect decreased to the minimum after that. Meanwhile mathematical model of the cyclical slit flow of concentricity under the moving boundary condition was established. The calculated values and experimental values are in substantial agreement and maximum relative error is no more than 8.5%, which showed the mathematical model is rational.