Abstract:The accuracy of HEV (hybrid electrical vehicle) engine control cannot be guaranteed because of the uncertain fuel consumption characteristic is a difficult problem. It can be resolved by the efficiency model of engine used by HEV. The theory that using the air exchange equivalent loss and the air exchange experience equivalent loss as the general efficiency model of naturally aspirated port fuel injection gasoline engine used by HEV was presented in order to determine the dynamically varied high efficient working region by theoretical analysis and by a lot of experimental investigation to a LJ491QE1 gasoline engine and a DA4G18—AA gasoline engine. The air exchange experience equivalent loss which only used two parameters of an intake pressure and an exhaust pressure could determine the dynamically varied high efficient working region of the engines and it has better responsiveness than the air exchange equivalent loss.

Abstract:The spray characteristics of biodiesel and diesel were studied in a constant volume combustion bomb by using high speed photography under high injection pressure. The effects of background pressure, background temperature, and injection pressure on the spray characteristics were studied by means of CFD code. The results indicated that the penetration of biodiesel decreased with the increase of backpressure; penetration of biodiesel increased with the increase of injection pressure; with the increase of background temperature, penetration of biodiesel began to fluctuate due to the high evaporation rate.

Abstract:A series of La2Cu1-xFexO4 catalysts were prepared by sol-gel, the samples were characterized by XRD、NO—TPD and H2—TPR, temperature-programmed test was used to evaluate the activity of the catalyst. It is found that La2Cu07Fe03O4 has a good PM—NO removal activities. So CDPF was prepared by La2Cu07Fe03O4 for the steady-state condition of the engine bench research, and by adjusting ECU to control fuel injection. When the crank angle between main injection and post injection was 70°CA, there was so much HC emission to significantly increase the conversion rate of NOx.

Abstract:The thermo-gravimetric properties of PM treated by non-thermal electro-discharge were studied by the experimental method. A non-thermal electro-discharge reactor was designed to trap PM based on the electrostatic theory, and a test rig for comparison and analysis was built. The content of soluble organic and solid carbon particles in PM was compared and analyzed by thermo gravimetric technology. The test and the analysis result concluded that non-thermal electro-discharge reaction can make soluble organic fraction produce incompleteness chemistry reaction. Voltage change of non-thermal electro-discharge is the key factor to affect the PM composition. Collection efficiency of PM for non-thermal electro-discharge reactor increased and the content of soluble organic fraction in PM decreased along with the voltage increase of non-thermal electro-discharge.

Abstract:The optimized design of orifices in the electro-hydraulic control valve actuator will affect the response and the impact of valve in the camless engine, and thus affect all aspects performance of engine. The mathematical model of the orifices in the valve actuator was designed, and the effects of the orifice’s diameter to the velocity during opening and landing were analyzed. The model of the camless electro-hydraulic valve actuator was built by using AMESim, the analysis of the influence to the diameter and related position of the valve orifices was done, the results showed that the orifice diameter decreased or the related position of damping chamber orifice increased resulted in the delay of opening time, and the orifice diameter decreased or the related position of main line orifice decreased resulted in the delay of closing time. The parameters of orifices diameter and position were optimized, and the demand of the valve was met by the optimized parameters through the experiments.

Abstract:The research of combined operation system of automobile gas heater and LNG engine can solve the problem of starting difficulty of the heavy truck using LNG. The stability of the combined operation and the effect of the combined operation on the cold starting performance of the LNG engine were studied through the combined operation tests. The experimental results showed that the automobile gas heater started smoothly and burned stably, and the cold starting performance of the LNG engine was improved significantly through the heating of the cooling liquid by the automobile gas heater. Therefore, adopting combined operation can improve the starting performance of the LNG engine in cold area effectively. 

Abstract:The changes of flow field and temperature field of underhood before and after the closure of the back door opening of a bus engine cabin were studied by the numerical simulations and experiments. The results indicated that after the closure of the back door opening, there are no notable changes of the flow field inside the engine cabin. In addition, the closure does not lead to the decrease of the cooling capacity of the cooling system. However, the temperatures near the former opening of the back door and the clutch increased slightly. Nevertheless, the closure of the opening of the back door cannot cause adverse impact to the performance of the bus.

Abstract:In order to solve the overlarge radial hydraulic forces on the impeller of screw-type centrifugal pump with single blade, splitter blade was added. Based on Navier—Stokes equations and k—εturbulent model, three-dimensional unsteady flow field of the pump was simulated numerically to the screw-type centrifugal pump with and without splitter blade. Pressure fluctuations in the outlet of pump, radial hydraulic forces on the impeller and volute were obtained at different flow rates. The analysis results indicated that the pressure wave in the outlet of pump, radial hydraulic forces wave on the impeller and volute were always periodic in the two models, impeller blade passing frequency was the dominant frequency. Compared with the result without splitter blade at different flow rates, the period decreased to a half, the amplitudes of pressure fluctuations in the outlet of pump was smaller, the radial hydraulic forces on the impeller decreased a lot, the distribution of radial hydraulic forces on the impeller vector coordinates were more symmetry, and almost ellipses, the radial hydraulic forces on volute increased a little, but the amplitudes of which was decreased, and the high-frequency components were also fewer. The analysis results indicate that the adding of splitter blade in impeller of screw-type centrifugal pump with single blade can not only decrease the radial hydraulic forces on the impeller, but also decrease oscillations in volute as well.

Abstract:An optimization design method based on three-dimensional inverse design method and CFD was developed by combining design of experimental method, response surface method and simulated annealing optimization calculation. The shape parameters of meridional channel and blade were taken as optimization design parameters, and the impeller efficiency was setting as the optimization object. The shape parameters of the blade were expressed by velocity circulation distribution parameters through three-dimensional inverse design method. The optimization method was applied to a centrifugal fan impeller with the efficiency improved by 3.3%. The effects of the meridional channel shape parameters, circulation parameters and their interaction effects on the impeller efficiency were analyzed according to the constructed response surface between the design parameters and the impeller efficiency. It is shown that the lean angle of the blade leading edge on meridional channel played an important role on the impeller efficiency. Compared with the hub, the shape curve and the circulation distribution shape on the shroud have more influences on the efficiency.

Abstract:The phase transformation in cavitation flow field was calculated by the full cavitation model considering the pressure and velocity turbulent fluctuation of the fluid, as well as the influence of noncondensable gas based on the homogeneous flow assumption. The turbulence viscosity coefficient was modified by the density function. A computation model and calculation method was proposed for the steady cavitation. The steady cavitation flow field of ALE15 hydrofoil was numerical simulated for the cavitation numbers of 2.3 by using the computation model and calculation method according to the conditions in the experiment. The calculated velocity distributions on different profiles agreed well with the experiment data, which validated the reliability of this computation model and calculation method. The velocity far away from the hydrofoil section was close to the velocity in the main flow region, and gradually decreased along the flow direction for the reason that the cavity acted as an obstacle. There is a large vortex zone in the cavity rear, and the velocity near the hydrofoil section is negative, both caused by the re-entrant jet. 

Abstract:The stress and deformation of centrifugal pump impeller have certain impacts on the velocity and pressure fields. A solution for the flow field of centrifugal combined with structure response of impeller was implemented by using two-way coupling method to investigate the effect of FSI of impeller on flow field. By using this method, various flow rate conditions were calculated. The results showed that the stress of the impeller was markedly uneven and the local stress concentration appeared in each operation condition. The back cover board of impeller outlet had large deformation deviating from the design value, which affected the impeller velocity, made the shunt parts in the volute to move export, led to severe unsymmetry phenomena and instability of pressure in impeller outlet. Pressure of every monitoring point changed obviously.

Abstract:Diffuser can improve the performance of tubular pump to a certain extent. Three dimensional laser Doppler velocimetry (3D-LDV) technique was used to measure the flow field in guide vane of tubular pump, and the velocity distribution inside the diffuser was obtained. The circumferential velocity gradually decreased from inlet to outlet, the axial velocity distributed like U-shaped, the velocity close to the wall was low, and the velocity of middle area was relatively high, the radial velocity distribution velocity was also relatively high speed. The flow field between experimental and numerical results agreed well with each other. It showed that the distribution of circumferential velocity and axial velocity were similar, but the radial velocity deviation between the LDV results and the CFD ones was big.

Abstract:With multiple nozzles and high head Pelton turbines, the increasing of nozzles will lead to mutual interference of flows in the runner, which reduces the efficiency of Pelton turbine. The working pressure at the root of bucket will increase obviously, and the safety factor of the hydropower station will be reduced. UG software was used to establish the model of runner bucket. By using CFD technique, the internal flow of a Pelton turbine with six nozzles was numerically simulated. ANSYS software was used to analyze the stress on the bucket. The runner bucket and profile line at the root were optimized. The problem of mutual interference among jets and internal flows was solved after the increasing of nozzles. The intensity and hydraulic performance of Pelton turbines were guaranteed. The designed unit has the characteristics of stable operation and high efficiency.

Abstract:Different moisture treatments （80%, 70% and 60% of field water holding）of summer maize soil evaporation were studied by using the conventional furrow irrigation and alternative furrow irrigation. The results showed that conventional furrow irrigation evaporation and whole growth period evaporation were greater than the alternative furrow irrigation. Within a short period after irrigation the surface soil with high moisture content, soil evaporation is larger; under the condition of meeting crop transpiration water consumption, alternative furrow irrigation reduced irrigation wetted area and thus reduced the invalid evaporation. With different furrow irrigation ways, soil evaporation and soil surface water content presented pulse fluctuations, while the deep soil moisture fluctuation is weaker; surface soil moisture content and leaf area index of soil evaporation effect are obvious, the two and the relative soil evaporation have a good relationship with exponential function. Moisture control is suitable, with alternative furrow irrigation, evaporation and transpiration water consumption decreased significantly and it is a suitable irrigation way for summer maize.

Abstract:In order to study the effects of regulated water deficit irrigation on soil moisture and temperature regimes in summer corn field of North China under subsurface drip irrigation, soil moisture and temperature, as well as canopy temperature, plant height, leaf area index, yield of summer corn in the whole growth stage were analyzed on the basis of a field experiment in Beijing. The results showed that the treatments, except for severe water deficit treatment, kept soil moistures in 20~60cm soil layer within a high and stable range; soil moistures for the well-watered control were higher than that for other water deficit treatments in 60~100cm soil layer; in all different soil layers, soil moistures had little differences for low and moderate water deficit treatments. Influenced by the degree of crop cover and water deficit, differences of soil temperatures and canopy temperatures among treatments were remarkable in the jointing stage; in upper soil layers (30~50cm), soil temperatures for the well-watered control were lower than those for other water deficit treatments before the jointing stage, but the differences among treatments were reduced after that; in deeper soil layers (80cm), the higher the deficit degree was, the higher the soil temperature would be. Finally, low water deficit treatment had higher corn yields, and moderate water deficit treatment greatly raised irrigation water use efficiency. 

Abstract:The experiment included four levels of the soil water deficit (threshold of soil water potential before irrigation) applied in the middle period of fragrant pear growth: slight (-100kPa), moderate (-200kPa),severe (-300kPa) water stress and the control (-50kPa). The irrigation system was surface drip irrigation. The results indicated that the water stress irrigation significantly reduced the summer pruning weight, improved the yield. Under full irrigation, the root length density (RLD) decreased with the increment of distance from the tree row, and root development in the wetted zone of drip irrigated pear tree was enhanced. The RLD at 0.5m from the tree row decreased with the depth; however, the RLD in the range from 1m to 1.5m from the tree row increased with the depth; in the non-irrigated zone at 2m from the tree row, the differences of RLD among the depths were not obvious. The RLD in the wetted and non-irrigated zone adjusted significantly due to the water stress in the wetted zone, as compared to the control. Increase of RLD due to the moderate soil water deficit showed some positive effects to the yield improvement.

Abstract:Totally 4 farm roads, i.e. the bare unpaved road, the stone covered road, the stone and grass covered road and the grass covered road, were selected on the representative area named Jiangxi Eco-science Park of Soil and Water Conservation. Twelve rainfall simulation experiments with an intensity of 3.0mm/min were carried out on the selected roads. The results indicated that runoff from the farm roads was recorded less than 2min. The runoff rate increased quickly and reached steady level in the first 2~6min. The runoff coefficient was above 65%. The erosion rate was high at the beginning of the rainfall and then decreased due to the loss of fine soil surface particles and porosity changes. At later period, the erosion rate of the bare unpaved road increased to some extent due to the appearance of rill and micro-gully. Compared with the bare unpaved road, the stone covered road, the stone and grass covered road and the grass covered road can all change the runoff hydraulic characteristics, so to protect the farm roads and decrease sediment yield. The lowest benefit of sediment reduction was up to about 40% among them, and the grassed road had the best benefit of soil and water conservation.

Abstract:Six main winter wheat cultivars planted in Shaanxi Province were used as test crops to study their differences in yield and nutrient use efficiency at different nutrient inputs by a two-year field experiment in Northwest China. The obtained results showed that winter wheat yield and biomass increased significantly with the increase of nutrient inputs, and the high-yielding varieties were more sensitive to the nutrient inputs than the low-yielding varieties. Analyzing yield components revealed that, in the low nutrient inputs condition, the yield depended on panicles per unit area and grain number per spike, but panicles per unit area dominated the yield in high nutrient inputs condition. In the low nutrient inputs condition, nitrogen recovery efficiency, agronomic use efficiency and partial factor productivity of the high-yielding varieties were 6.3%～61.6%, 52.1%～122% and 9.8%～25% respectively, higher than those of the low-yielding varieties. Phosphorus recovery efficiency, agronomic use efficiency and partial factor productivity of the high-yielding varieties were 31.2%～33.3%, 58.9%～126.3%, 7.0%～24.9% respectively, higher than those of the low-yielding varieties. Nitrogen and phosphorous partial productivity significantly decreased with the increase of nutrient inputs, and the low-yielding varieties were more sensitive to fertilization input than the high-yielding varieties.

Abstract:A wireless hot-film wind speed profiler as well as its data acquisition and processing system were developed in order to avoid large measuring errors and inconvenience of moving by using conventional pressure differential wind profiler. The tested system was calibrated in soil-erosion wind tunnel. The system can implement multi-points data acquisition and wireless transmission, with the advantages of simple construction, reliable performance, easy carry and installation, anti-contamination and wide range of speed measurement. The experimental result showed that for the calibrated wireless hot-film wind speed profiler, the calibrated error is less than 0.3798m/s, and the measured wind velocity profiler is in exponential distribution, which is in accordance with the characteristic of wind speed perpendicular distribution at near soil surface.

Abstract:Fast pyrolysis experiments of pine and corncob were conducted in the fluidized bed reactor with a feed rate of 1kg/h, and bio-oils with different properties were obtained by spray condensation. Effect of condensing temperature on properties of bio-oils was investigated. The results of experiments showed that yields of bio-oils from pine and corncob were reduced by 23.1% and 20.8% respectively, and water contents were also decreased by 11% and 18% respectively, while viscosities went up by 181cSt and 10cSt respectively, and heat values also increased by 6.23MJ/kg and 5.04MJ/kg respectively when condensing temperature rose from 25℃ to 75℃. The chemical compositions and structures of bio oil were analyzed by gas chromatography/mass spectrometry (GC/MS) and nuclear magnetic resonance spectroscopy (NMR). From the GC/MS spectra it was observed that the contents of anhydrosugar significantly increased in bio-oil from pine, while the contents of most light components decreased with the rise of condensing temperature. In bio-oil from corncob contents of anhydrosugars and phenols were both slightly enhanced, while contents of organic acids, aldehydes and ketones were reduced in bio-oil from corncob. The 13C spectra revealed that the content of alkyl carbon decreased, while the content of aromatic carbon increased in bio-oils with the rise of condensing temperature, and thus aromaticity of bio-oil was raised.

Abstract:The cellulose from wheat straw was pretreated with propionic acid, and the content of glucose at different reaction temperatures was determined. Based on the Saeman model, the kinetics data of cellulose hydrolysis and glucose degradation were calculated. The activation energy was 6.5086×104J/mol and 5.6223×104J/mol, respectively. The analysis results indicated that cellulose has a faster hydrolysis rate, and the glucose formed is easy to degrade. The optimum reaction conditions are 80℃ and 176min, and the content of glucose reached 8.89g/L. The adequacy of the model for predicting is verified effectively by the validation．

Abstract:The plant fiber tableware dry-hot forming process was optimized by response surface methodology. Three independent variables, such as molding pressure, molding temperature and molding time have significant effects on the appearance quality of tableware. A three-factor quadratic regression rotation combination design was employed to study the response, and the interaction of the factors on the appearance quality was also investigated. By analyzing the response surface, a polynomial regression equation was obtained and the optimal conditions of dry-hot forming process were gained, they are: molding temperature of 181℃, molding pressure of 18MPa, and pressure duration time of 9s.

Abstract:In order to improve the performance of vertical axis wind turbine, the variable pitch vertical axis wind turbine (VAWT) was studied. The optimum pitch angles at different azimuth angles were calculated by the blade element theory to maximize the drive moment of blade at any position. After doing dynamic regional UDF (user-defined function) approach on sliding mesh, dynamic mesh and a combination of both, the diverse numerical simulation methods of active control for variable pitch vertical axis wind turbine were built. Finally, the total torque generated as well as the power coefficient were obtained. The reliability of numerical simulation was verified by comparative analysis between the experimental and simulation results about VAWT. The results indicated that the power coefficient of vertical axis wind turbine was improved by the method of variable pitch, especially in the case of low tip speed ratios (TSR), where the capability of self-starting was improved greatly. Compared with the fixed-pitch vertical axis wind turbine, the power was increased by about 90% at the tip speed ratio of 1.5, 2.0 and 2.5.

Abstract:Aiming at the fact of low efficiency packaging to the agricultural products and the poor standardized identification, a kind of agricultural products original habitat anti-counterfeiting identification packaging system was put forward. It integrated the functions of case sealing, identification and dynamic anti-counterfeiting identification. It solved the problem of the present equipments that sealing and labeling must be done separately. It integrated static identification and data inauthenticity. The practice indicates that the system can improve the packaging efficiency and the identification authenticity. 

Abstract:A combined system driven by solar energy and used in vegetable growth and distribution center was designed. This combined system used solar energy as the assistant heat source, water and CO2 as the working fluid. It can provide fit temperature environmental space needed by many different locations such as vegetable growth, pick, wash, pre-cooling, cooling storage (or quick freeze and frozen storage). By calculation and analysis to the combined system driven by solar energy and used in four representative areas selected in China, and the comparison between the combined system driven by solar energy with that driven by full-electricity, the results were obtained. They show that the performances of the combined system driven by solar energy in different areas have obvious differences. In Guangzhou area, the combined system driven by solar energy saved about 69.6% of electricity and the running cost in a year due to the higher environmental temperature. In Lanzhou area, the combined system driven by solar energy economized about 60% of the electricity and running cost in a year owing to the higher solar radiation intension, and in Urumchi area, the combined system driven by solar energy can also reduce about 49.2% of electricity and running cost in a year. However, even though the lower environmental temperature and solar radiation intension in Beijing area, still the electricity and running cost consumption of the combined system driven by solar energy reduced by 7.8% all year round too.

Abstract:The effect of high hydrostatic pressure (HHP) treatment and heat treatment on the stability of Agaricus bisporus mushroom polyphenoloxidase (PPO) was studied. Residual activities of the PPO were investigated after HHP treatment at 100~1600MPa for 0.2~25min and heat treatment at 55~80℃ for 0.2~20min. The HHP and heat inactivation kinetic of mushroom PPO were analyzed by first-order and biphasic model. The results showed that the effect of inactivation was improved with the pressure and temperature increasing, as well as the treatment time increasing. The residual activities were all higher than 88% when treated at pressure lower than 600 MPa, indicated that treatment at pressure lower than 600 MPa had limited influence on the activity of PPO. After HHP treatment at 800, 1000, 1200, 1400 and 1600MPa for 25min, the residual activity reduced to 66.42%, 52.83, 27.20%, 2.20% and 0.01%, respectively. The first-order model was used to analyze the survival curves of heat treatment. All of the coefficients of determination (R2) were higher than 0.960, which proved that the first-order model fit the microbial inactivation kinetics curve well. However, as R2 were all higher than 0.982, the biphasic model was proved to be more suitable than the first-order model to describe the kinetics of PPO inactivation treated by HHP.

Abstract:With the aim to investigate the effect of postharvest dehydration on dielectric properties of grape during cold storage, the dielectric parameters of the Red Globe grape were measured at 0.1kHz，1kHz，10kHz，100kHz and 1MHz by using LCR electronic measure instrument, and the results were compared with those of un-dehydrated grape under the same condition. For the un-dehydrated and dehydrated grapes, both of them have the same trends at same storage day: the impedance, reactance, inductance and resistance were all gradually decreased while the susceptance increased with the increase of the frequency; and the loss tangent, dielectric constant and impendence phase angle firstly decreased with the frequency increasing from 0.1kHz to 100kHz, and then increased at 1MHz. Compared with the un-dehydrated grape, the dehydrated one has higher impedance, reactance, inductance, resistance and lower dielectric constant, impendence phase angle during 45 days storage. All the test results show that postharvest dehydration is a more effective way in keeping the quality of grape during cold storage. 

Abstract:For automatic determination of acid value and peroxide value of edible oils, using edible oils as raw materials, calibrations were developed and validated for determination of acid value and peroxide value by near-infrared spectrometer with continuous samples injection cell. The correlation coefficient R and the root mean square errors of prediction (RMSEP) of the calibration for acid value were 0.9873 and 0.114mg/g in range of 5500～4600cm-1 with baseline correction point at 6524cm-1 and 4823cm-1 and standard normal variant (SNV). The R and RMSEP for peroxide value of calibration were 0.9958 and 0.90mmol/kg in range of 6050～4450cm-1 with first derivative and Norris filter. The results of blind samples validation were good, the calibrations were workable, throughput of 90 samples can be achieved per hour.

Abstract:In order to improve the detecting accuracy rating and stability of total flavonoids content in ginkgo leaves by near infrared spectroscopy technique, a precision model was established by selecting efficient spectral regions combined with different partial least squares (PLS) selecting wavelength regions methods. Three improved partial least squares (PLS) methods, including interval partial least squares (iPLS) selecting wavelength regions method, backward interval partial least squares (biPLS) selecting wavelength regions method and synergy interval partial least squares (siPLS) selecting wavelength regions method were used to find the most informative ranges and build models with better predictive flavonoids content in ginkgo leaves at first. And then the models were compared with PLS model which was developed on the whole wavelength range 4000~8000cm-1. Results showed that the models built by the three improved PLS methods had higher predictive ability than that of PLS method. The optimal model was the one that obtained by siPLS selecting wavelength regions method and it separated the whole spectra into 21 intervals and combined two intervals including interval 7 and interval 12, the RMSECV and RMSEP were 2.9500 and 3.000, calibration and the prediction correlation coefficient were 0.9384 and 0.9437. The conclusion is siPLS method can accurately and rapidly predict flavonoids content in ginkgo leaves.

Abstract:In order to realize the rapid identification of different varieties of pears, principal component analysis (PCA) on the spectral data clustering analysis was used on three different varieties of pears to find the characteristic differences. The principal component analysis showed that the main composition PC1 and PC2 for all the modeling samples score diagrams had very good clustering effect to the different types of pears. Load diagram that got by using principal component analysis can obtain the variety sensitive characteristic wavelengths from pears, and with the characteristic band spectrum as input to build partial least-squares discriminant (DPLS) and least squares support vector machine (LS—SVM) models. Seventy pears of three varieties with 210 in total were used to build DPLS and LS—SVM models respectively. The unknown 24 samples were predicted by the models, the recognition accuracy rate of the LS—SVM model reached to 100%. The calibration and verification results of the DPLS model and the actual classification variables of the correlation coefficient was greater than 0.980. Cross validation root mean square error (RMSECV) and root mean square error of prediction (RMSEP) were less than 0.100. The varieties recognition rate was 100%. The proposed rapid identification method has good classification effects. 

Abstract:A strawberry-picking robot was developed, consisting of a crawler walking mechanism, a machine vision based precision motion positioning mechanism, and an end-effector cutting and gripping strawberry peduncles synchronously, for application to an elevated substrate culture. And the robot was controlled by a layering control system whose kernel was ARM9. The field test in greenhouse indicated that the robot could recognize, locate and pick ripe strawberries in elevated substrate culture with the success rate of 88%, without damaging the fruits, and the execution time of a single pick cycle was 18.54s.

Abstract:The coordination and coupling among agricultural parallel robot’s chains relative to the end actuator became a difficult problem in parallel robot motion control. Aiming at this, a control method that combined synchronization control with sliding mode control was proposed. The simulation results show that the control method has good tracking performance, high speed responsibility, small system error and strong robustness. It satisfied the requirements of the parallel robot control.

Abstract:A new supervised weighted LLE method based on the Fisher projection was proposed. This method utilized the Fisher projection distance to replace the sample’s geodesic distance, and the importance score of each sample was obtained based on this distance, then the importance scores were added into the cost function of LLE. This method can overcome the disadvantage of traditional LLE, an unsupervised learning algorithm which cannot solve the classification problem very well, and can exploit the category information better and reduce the influence of noise points at the same time. The experimental results based on the real-world plant leaf databases show its mean accuracy of recognition is up to 92.36%.

Abstract:A method of recognition weeds during cotton emergence based on principal component analysis (PCA) and support vector machine (SVM) was developed. For the effective classification of the variety of weeds in cotton field, the dimension of feature variable space was reduced by extracting color, shape, texture characteristics and principal component analysis. The experiment of classification for 120 samples of cottons and weeds showed that it was able to reduce training time and increase classification accuracy effectively by the first three principal components obtained by PCA dimensionality reduction. It was found by comparison that the best classification and recognition result was obtained by using the combination of the first three principal components and RBF kernel function SVM. The training time is 91ms and the average correct classification rate is 98.33%.

Abstract:For effective completion of tractor dynamics test and developing its control units, the technology requirements for general sensor installation bracket on tire center position was firstly determined, then the detailed structure was optimized and processed. The designed mass of bracket was 1.815kg and its axial length could be adjusted. The designed structure ensured that the principal plane of bracket was parallel to the tire rotary plane and its rotation center was aligned with the tire rotation center. The finite-element simulation analysis showed that the max deformation of the bracket was less than 0.2mm when loaded with vertical and rotation inertial forces at speed of 90km/h on the worst H level road, so it could not add systematical error on the measurement data. A roadway test system was developed and the reliability of the bracket was verified by the systematical roadway tests. This research provided a general and effective means to study the measurement problem on the rotation tire center, such as tractor assistant driving navigation system for mechanized working in small or medium scale farmland, tractor tire dynamics test, and so on.

Abstract:A method based on Vis/NIR spectral analysis technology was applied to the rapid measurement of pesticide contentration on the leaf. Near infrared spectral data of pesticide concentration on the leaf was acquired by adopting diffuse reflectance spectroscopy. Normalization of standard deviation, moving average smoothing with the segment size 3 and the first derivative combination was the optimal combination pretreatment method. From the seven schemes in contrast, the optimal hands for 350~1900nm were obtained. Partial least squares method was used to develop the quantitative analysis model for pesticide concentration with diffuse reflectance spectroscopy. The correlation coefficient between the prediction values and the truth values in the prediction set was 0.994, the root mean square error of cross-validation of the prediction set was 0.039. The result indicated that it is feasible to measure pesticide concentration on the leaf based on the near infrared (NIR) spectroscopy, and the accurate actual pesticide concentration on the leaf can be obtained after spraying pesticides.

Abstract:Dielectric elastomer actuators are operated in static domain. Aiming at the influence of the material property of dielectric elastomer and the structure of cylindrical actuator on the static characteristic, the main influencing factors on axial force of dielectric elastomer cylindrical actuator were studied. Adopting hyperelastic Yeoh model and simulation software ABAQUS, the axial force change of cylindrical actuator was analyzed under the condition of dielectric elastomer side lateral contraction, circumferential relaxation after convolution and compression between film layers. Compared with the actual actuator dimension, it is found that the circumferential relaxation after convolution is the most influential factor with respect to the axial force of cylindrical actuator, and the error is up to 25.9%. The two latter influence factors were taken into account and the error is less than 5% between the calculated result and the experiment. Finally, the quasi-static stiffness of cylindrical actuators was further studied, and the conclusion was gotten through the experiments that the film layer slippage can not be negligible when cylindrical actuator experiences large displacement.

Abstract:The disadvantage of current compliant pairs used in micro-displacement fields are that they produce micro-deformation rather than macro-scale deformation. In order to solve this problem, a new compliant revolute pair was proposed based on the theory of elastic deformation which can provide macro-scale deformation according to its own elastic deformation. The model of flexibility matrix was established, and rotation error was calculated with Matlab software and analyzed in Ansys. The results showed that the relative rotational stiffness error was 5.6% and relative rotation error was 3.4% according to the two methods. Finally, a test of the compliant revolute pair was carried out to justify the two above-mentioned results. It showed the flexibility analysis is reasonable.

Abstract:Based on two-part cutter head, the mathematical model of epicycloid hypoid gear pair was built through face-hobbing cutting method and generating principle. The relationship between assembly misalignment and meshing behavior was described by the results of tooth contact analysis. In the situation of transmission performance requirements, the parameters of wheel blank and processing parameters were designed. Based on a pair of epicycloid hypoid gears, the influence of each assembly misalignment on the meshing and transmission performance was analyzed.

Abstract:In order to obtain tooth contact quality and adjust the contact area, the tooth contact analysis based on predetermined position was studied based on generation method with tilt of prolate epicycloid bevel gears. The cutting movement was analyzed, and the cutting mathematical model with tilt was established according to the relative position and motion among cutter, cradle and workpiece, and the theoretical tooth surface equation was derived. The tooth testing model with axis position variable was established, the simplified tooth contact analysis algorithm was derived, the solved method about contact ellipse was given, and the solved process about tooth contact analysis based on predetermined position was provided. Finally, a pair of prolate epicycloid bevel gears was analyzed on different predetermined position, and the result shows that the simulation results are in accordance with the testing results, and the effectiveness of tooth contact analysis algorithm is verified.

Abstract:An interface information model for the combination and matching judgment of modules was established, which included six parameters: coding, module attached, type, geometry, critical geometric parameters and function flow direction of interface. Among these six parameters, the type of interface included dynamic interface and static interface, and the functional flow direction included function input and function output. The first two parameters were mainly used for the identification and retrieval of interface, and the other four were used to determine the relationship between modules, including connection and interchangeable. An example was used to illustrate the validity and rationality of the established model.

Abstract:In traditional through transmission ultrasonic detection for curved components with variable thickness, the amplitude of receiving pressure was unsteady and the signal to noise ratio was always low. In order to solve this problem, an acoustic modeling method, called multi-Gaussian beam superposition technique was introduced into the curved component ultrasonic detection system. A receiving pressure model was established to analyze the effect on receiving pressure under different parameters. Analysis and the experiment results showed that the receiving pressure is very sensitive to the probe position and orientation. The angle existed between ultrasonic beam propagating path and probe position and orientation planning by conventional path generation method shouldn’t be ignored. Taking bi-cubic B-spline surface workpiece for example, a new probe position and orientation planning method was proposed based on tracking ultrasonic beam propagation. The triggering probe position and orientation was planned firstly by regular method, then the receiving probe position and orientation was decided by tracking beam propagation form the trigger probe. Compared with the conventional method, practical application showed that the receiving signal is better and the detection results are more accurate by the proposed method.