Abstract:The simulation model and hysteresis compensation control method of proportional relay valve of EBS for commercial vehicle were proposed focused on the hysteresis characteristic. First, the mathematic model for proportional relay valve was established, which reflected the hysteresis characteristic. Then, the response characteristic and hysteresis characteristic were simulated using that model in Matlab/Simulink environment, and the correctness and reliability of the model were validated through opened loop test. After that, a control method for proportional relay valve was developed by which the hysteresis characteristic could be compensated. Finally the effectiveness of this control method was validated through the off line simulation and the HIL test. Simulation and test results show that the hysteresis compensation control method proposed can improve the control characteristic and vehicle active safety.

Abstract:Projection-to-plane model of the Steering linkage has low accuracy. Multi-body dynamics model is inconvenient to use complex optimization algorithm. To deal with these difficult problems, a spatial structural nonlinear modeling of the steering linkage in an 8×4 type heavy duty truck was developed using the rotation vector method of the spatial RSSR four-rod mechanism. The steering-wheel angle was the model input, and the steering wheel deflection was the model output. The steering linkage was broken up into six spatial RSSR four-rod mechanisms according to the angular displacement transfer path. Through establishing each RSSR mechanism model and then integrating them, the angle relationship between the steering-wheel and steering wheels was acquired. The simulation and test results showed that the Ackerman deflection errors of the right steering wheels of the first and second steering axles reduced 50% and 28.6% respectively in the spatial model comparing with the projection-to-plane model. The results also showed that the maximal deflection error of the spatial model in all the steering wheels was 1.8° relative to the test results, while the error of the projection-to-plane model was 3.9°. In the whole steering-wheel angle, the spatial model had high accuracy. The spatial model described the mathematical relationship of each moving component in the steering linkage distinctly. The model may provide theoretical foundation for analyzing the moving interaction between the suspension and steering linkage and the optimal design of the steering linkage.

Abstract:Aiming at a car modified as SUV, the layout of the front Macpherson steering suspension system needs to be redesigned after raising the car body. As a result, the toe-in of front wheel changes towards a positive rate in the process of the wheel jounce, which causes the vehicle tends to over steer. And Ackerman deviation is large which makes severe tire wear in progress of turning around. According to the structure characteristics of Macpherson suspension mechanism, the kinematics of suspension is analyzed based on space geometry method when it has or not has the steering linkage. And the influences on the amount of toe-in and camber of steering linkage are found. The optimization model is set up based on the influences on toe-in of steering linkage and space limitation of splitting point, which is calculated with Matlab. After optimization, the toe-in deterioration is eliminated, and Ackerman deviation is effectively reduced. As a result, the handling and stability of the vehicle and tire wear are improved in progress of turning around.

Abstract:In order to get the accurate and real-time vehicle state variables in running, a new kind of model adaptive update particle filter method is proposed. The non-Gaussian and non-linear tire noise vehicle dynamics model is established. High frequency sub-band is used to estimate real-time measurement noise variance of sensors based on the wavelet transform. The real fitting degree of observation likelihood function is improved and the degradation phenomenon of particle weight is improved to a certain extent by the combination of the adaptive auto regression model of the whole vehicle system state. Virtual experiment based on ADAMS/Car and real vehicle experiment verify the validity of the proposed method. Experiment results show that the estimation precision and anti-noise performance of the proposed method are superior to those of the commonly used method, and can satisfy the requirements of vehicle state estimation.

Abstract:This paper presents a real-time measurement method of vehicle transmission shaft dynamic torque, which was based on two single-port SAW resonators. Using three-point equidistantly and symmetrically arranged signal transceiver antenna, the diffraction of signal was eliminated. The control circuit of signal transmitting and receiving sequence was achieved with PWM signal, therefore, the hardware circuit was simplified. Modeling of SAW torque sensor measurement with frequency difference was introduced into this measurement system,, and the influence of temperature or other factors was reduced and the measuring accuracy was improved. Theoretical and experimental results were compared and the results showed good agreement and supported the validity of the SAW torque sensor model. Obtained measurement sensitivity was 1.15 kHz/(N·m), and a feasible solution for vehicle transmission shaft dynamic torque measuring was provided.

Abstract:Aiming at the non-electronically controlled single-cylinder diesel mainly applied for agricultural machinery, the electronically controlled CNG gas supply system was only increased to modify the engine but maintaining the original mechanical part. Theoretical analysis and experimental measurement of instantaneous speed for single-cylinder diesel were conducted. The law of single-cylinder instantaneous speed variation was summarized, and based on the law a position determination strategy was proposed. An experimental scheme for CNG-diesel dual-fuel single-cylinder diesel was designed. After implemented the strategy and CNG injection driver on microcontroller, bench tests were carried out. The results showed that position determination based on this strategy achieved good accuracy and the engine ran stably, both under stable and variable engine conditions.

Abstract:Aimed at the problem of low processing speed and poor anti-interference in existing algorithms for the visual navigation, an algorithm based on improved genetic algorithm (IGA) was designed for navigation line detection. Since the trend of crop row in image was approximate to a line, two points from the bottom and top sides of image were randomly selected to code as chromosome. By multiple genetic evolutions, the highest fitness individual was chosen as the crop row line, so as to obtain the navigation line. To increase search efficiency and accuracy, IGA adopted the method of combination of probability preservation and optimal preservation strategy as the selection operator. The probabilities of crossover and mutation were adjusted automatically to improve the convergence speed and global search ability. The experimental results showed that, compared with Hough transform and Generic algorithm, IGA had the advantages of rapid detection and strong anti-interference. When the velocity of the vehicle was 0.6m/s, the maximum lateral deviation and average lateral deviation were 76 mm and 33.1 mm respectively, which could meet the requirement of farm machinery navigation.

Abstract:Taking mobile targets, such as agricultural vehicles and mining equipments, as the research object, the position and pose tracking technology is proposed under three-axis accelerometer and three-axis gyroscope aimed at realizing autonomic movement in unknown environment. Firstly, dynamic characteristics and kinematic model are built. Secondly, using three-axis accelerometer, the position and pose of mobile target are resolved based on the multi-parameters. Then, a prototype system for verifying the proposed position and pose method is developed. The estimation results indicate that the mean errors of roll, pitch and yaw are 0.33°, 0.26°and 0.38° respectively under static state, while the dynamic errors of pose detection are 1.01°, 0.64° and 0.83° respectively. The mean errors of position estimation are 0.76, 0.52 and 0.56 m respectively under static state. Meanwhile, the accumulation error caused by three-axis accelerometer can be eliminated under the aid of zero-velocity update, which can effectively track the trajectory.

Abstract:Agricultural aerial spraying is an effective guarantee to achieve food security and ecological security in China. In this article, the research status of agricultural aerial spraying technology in China was reviewed and summarized. Three aspects such as models of agricultural airplane, key technologies of aerial spraying and supporting equipments in aerial spraying were elaborated, and then the prospect of China's agricultural aerial spraying was expected through comparing the current situation of aerial spraying with developed countries. It will provide progress reference for scientific research and development of domestic research institutions and enterprises.

Abstract:A platform was built up to collect the pressure data near the nozzle. The instantaneous flow data was calculated based on the relationship between pressure and flow by using Kalman filtering algorithm, and the average spray flow rate was obtained by integrating over the instantaneous flow, then an automatic piecewise linear fitting method was designed after considering the relationship between the duty cycle of PWM signal and the average spray flow rate. In order to verify the control effects of the spray flow rate model, the PWM spray flow rate models based on Kalman filtering were established under the spray pressure of 0.2, 0.3 and 0.4MPa, respectively, and the experiments of spray flow rate control accuracy were performed under the same conditions. The results showed that the coefficient of determination (R2) in the models above were all more than 0.995 under the three spray pressures, and the spray flow rate control error was within ±6%. This method provides a reference of building spraying control model for rapid and online use.

Abstract:Aerial spraying may easily lead to loss of droplets with the wind from crosswinds and influence of spray effect. This article analyzes related factors which influence spray drift behavior, and sets up the motion equations of the droplet in three-dimensional coordinate system. A prediction model of droplet drift under crosswind condition is received so that the droplet drift distance can be predicted by calculating. Spray drift experiments are done under different flow and spray conditions by using wind tunnel with the droplet concentration testing method. Actual droplet drift distance in the wind tunnel conditions are obtained through simulation of the linear regression method. Experimental results show that as the air velocity increases, spray drift distance increases significantly, and droplets with diameters less than 200 μm under crosswind are more prone to drift. For the large droplets with diameters bigger than 250 μm, although the drift along downwind direction of the wind tunnel still happen, the drift distance is shorter since the kinetic energy of the vertical direction is relatively larger. Through analyzing and comparing droplet drift distance from prediction model with the results of calculating and estimates, it is observed that the results meet the requirements. It is concluded that the motion model of droplet as the dominant expression of spray drift behavior is feasible.

Abstract:The reliability of high clearance boom sprayer chassis was studied by simulation and experiment. The stress distribution and the weak positions of the chassis were simulated by software ANSYS. According to the finite element results, the relation equations between the load of testing points and weak positions were obtained. The load spectrum measurement experiments of spray machine chassis were carried out under typical using conditions. In data statistics processing, the rain-flow method was adopted. By means of the Miner’s rule, the cumulative damages of weak positions of the chassis under various typical conditions were calculated. According to the actual use of the spray machine, the real life of the chassis was calculated by a weighted average of the damage under various typical conditions. The research method and the analysis results can provide guidance for reliability design of agricultural machinery.

Abstract:Centrifugal fan is one of the important parts of the combine harvester, and study on its internal flow field distribution is of great importance for the structural design of the fan. Single duct centrifugal fan is commonly used in air-and-screen cleaning device of the existing full-feed rice combine. And it has the problems of unstable internal flow field, uneven outlet velocity and fast wind speed attenuation. In order to solve those problems, the channel model of the fan was established by using Solidworks software. Meshing it with ICEM software and simulating it in Fluent software, the internal flow field in centrifugal fan was simulated. The results showed that the wind speed at upper outlet and external rim of impeller was larger, and the pressure of impeller runner increased along radial direction. The wind speed of lower outlet Ⅰand Ⅱ and Ⅲ increased successively, and the decline rate decreased, which was useful for the air flow covering the whole sifter. Transverse air flow was nearly layered distribution on the upper outlet. Transverse air flow of middle outlet among three lower outlets was the largest, and that of other two outlets were symmetric. Maximum value of wind speed, air quantity and pressure of upper outlet and lower outlet Ⅱ and Ⅲ increased with fan speed increasing. Maximum value of each outlet’s air quantity and wind speed decreased with inlet diameter decreasing and the change of lower outletⅠwas more obvious. Variation of upper and lower separating board angle had a great change on wind speed and air quantity of lower outlet. The research of this paper provides basis for designing double outlet and multi-duct centrifugal fan.

Abstract:Taking a tangential-axial combine harvester as a research object, a fuzzy adaptive control system of forward speed based on model reference was put forward, and the multivariate fusion reference models under adaptive control and the fuzzy control rules were established. Then, the control device of forward speed for the combine harvester was developed, and the field harvesting tests of rice were made to verify the feasibility of the device. The results proved that the model reference fuzzy adaptive control system could implement the adaptive control function of the forward speed for the combine harvester compared with the ordinary fuzzy control system, which effectively reduced the labor strength and increased the harvesting efficiency.

Abstract:In order to reduce the working resistance of soil compaction and the problem of tractor tire caused by crop stubble, a kind of cultivating combined front-stubble-breaking, post-subsoil and rear-rotary-tilling was design based on single and combined work of cultivating machines, and the field test was carried out. The experimental results showed that 1ZQHF350/5 front-stubble-breaking, post-subsoil and rear-rotary-tilling combined cultivating could enhance the stability of the tractor. The energy saving was about 6.2% and the ratios of pulverizing soil and stubble-breaking were improved above 2.3% and 5.8%, respectively. The problems and measures were analyzed in the process of application and promotion, which provided reference for study of large agricultural implements.

Abstract:In order to real-time and accurately obtain the multi-point wind speed of all the key regions and rotate speed of the big and small mesh rollers during running of the mesh roller-type unginned cotton and film remnant separator, the automatic monitor system was designed and developed based on virtual instrument technology combining with a variety of sensors. Finally, the value acquired by system was compared with the measured data of the handheld laser tachometer and the four-channel intelligent pressure data collecting instrument for wind speed and volume. Experimental results showed that the maximum relative error of rotate speed of the big and small mesh roller was 0.68%, and the maximum relative error of wind speed was 8.95%. The result indicated that the monitor system met the measurement requirements for collecting wind speed and rotate speed and the system was reasonable and practical.

Abstract:Directed sowing corn can make the corn growthconsistent, increasing core planting density and yield of crops. Corn directional sowing tapes was one of the methods to realize the directional seeding. In order to ensure that seed direction deflection did not occur in the process of adsorption, we designed the seed adsorption arranging mechanism, and established the mechanical model of joint adsorption of seed. Software Fluent was used to make simulated analysis of the seed suction airflow field. Taking suction cone angle, hole spacing, and lateral plate width as three factors, an orthogonal experiment was carried out, and the directional absorption-arranging of corn seeds was determined. The best suction model parameters were as following, suction cone angle was 60°, hole spacing was 1.5 mm, lateral plate width was 4 mm, and air velocity was 6~8 m/s.

Abstract:There are a lot of problems in deep application-type liquid fertilizer such as large energy loss, low efficiency, transporting liquid fertilizer hose winding, etc, because of intricate piping in splitter and fertilization institutions of deep application-type liquid fertilizer. Hence, we designed a rotor type liquid fertilizer converter by theoretical analysis and Adams simulation method in order to solve the above problems. Using the converter, which could replace original splitter and any original tubing of fertilization institutions, we designed the pipe system of transporting liquid fertilizer. We used the new pipeline system with the converter in an anti-winding test. We also used the new one and the original pipeline for a comparative fertilization experiment. When finished the anti-winding experiment we found that when the sun gear and the planetary gear ratio was 3∶1 and the sun gear and the planet carrier speed ratio was 2∶3, the converter applications could better solve the transporting liquid fertilizer hose winding problem of fertilization institutions. When finished the comparative fertilization experiment we found that the new pipeline system efficiency was 2.63 times of the original pipeline system when fertilizer was 20.32 mL/time and pump pressure was 0.31 MPa.

Abstract:Two-year (2011—2013) field experiment was carried out to investigate the effects of straw pretreatment (comminuted or ammoniated) on soil moisture dynamics (0~100 cm depth) in the whole growth period of winter wheat, crop water consumption, water use efficiency (WUE) and precipitation use efficiency (PUE). The results showed that the changes in soil water storage (0~100 cm depth) under all experimental treatments were similar in the whole winter wheat growing period in 2 -consecutive-year. The ammoniated straw application increased soil water storage (0~100 cm depth) by 4.95% and 1.82% at the maturity stage significantly in two years respectively more than conventional straw mulching, and by 4.24% and 1.75% more than unammoniated straw application. In terms of crop water consumption, conventional straw mulching, compared with conventional straw incorporation, effectively reduced the total water consumption in the growing periods of winter wheat. In addition, the comminuted-ammoniated straw application, compared with unammoniated straw application, also observably reduced the total water consumption at the late growth stage of winter wheat, which promoted the use of irrigation and precipitation by winter wheat. Pretreatment (comminuted-ammoniated) straw application, compared with conventional straw mulching, significantly increased the grain yield of winter wheat by 9.07% and 11.42% in 2 years respectively, which improved winter wheat WUE and PUE significantly as well.

Abstract:Parameter sensitivity analysis is crucial to the process of model localization. In this study, both the Morris and EFAST (extended Fourier amplitude sensitivity test) methods were applied to test the sensitivities of outputs of CERESWheat model to its cultivar and ecotype parameters. The wheat crop planted during 2007—2010 was simulated under the potential, attainable and actual yield level at Yangling, Shaanxi Province. CERESWheat outputs of interest included anthesis date, maturity date, yield and above-ground biomass. The results showed that the anthesis and maturity dates were highly influenced by photoperiod response (P1D), accumulated temperature in the duration of emergence stage to terminal spike differentiation stage (P1), accumulated temperature in the duration of terminal spike differentiation stage to flag leaf stage (P2), and vernalization effect (VEFF). Moreover, maturity date was sensitive to grain filling phase duration (P5). Yield and above-ground biomass were highly influenced by PAR before and after flag leaf stage (PARUE, PARU2), P1D, P1 and P2. Moreover, biomass was sensitive to standard kernel size (G2) and kernel number per unit canopy weight at anthesis (G1). The correlation coefficient between the Morris mean and the EFAST total sensitivity index was high, indicating that the Morris method with less computation could be used to select the sensitive model parameters.

Abstract:Lattice Boltzmann method is applied extensively in the field of fluid motion for concise programming, parallel computing, and dealing with complex geometrical boundary easily and so on. As the main force of soil water erosion process, accurate simulation of the process of overland flow has important significance for analyzing the mechanism of slope erosion and building the physical process of soil erosion model. However, there is less research on the application of the lattice Boltzmann method to overland flow at present. In this paper, lattice Boltzmann method with D1Q5 velocity model is applied in motion equation of overland flow, in which, only time is considered in the process of multiple scales, and undetermined coefficient method is adopted to determine the equilibrium distribution function by means of multi-scale analysis. And then using analytical solution as a standard, lattice Boltzmann method and Preissmann four-point implicit scheme method are compared through ideal numerical example. The results indicate that the calculation precision of lattice Boltzmann method using D1Q5 velocity model is higher than that of Preissmann four-point implicit scheme method in simulating the variations of water depth and discharge per unit width at the bottom of slope, especially in the stage of recession flow, and in describing the distribution of water depth and discharge per unit width along the slope length before equilibrium time. But after equilibrium time, the calculation precision of lattice Boltzmann method using D1Q5 velocity model is lower in calculating the distribution of water depth and discharge per unit width along the slope length because at the point of x=1 m, a large relative error occurs. The relaxation time is recommended to be taken in ［1, 1.2］ s when lattice Boltzmann method is applied to solve the motion equation of overland flow.

Abstract:The initial soil infiltration rate affects and determines rainfall runoff, hydrological processes and soil erosion process. A new experimental method and device were suggested to test the initial infiltrability of soil under ring infiltrometer. The water distribution in the soil profile as made by the initial infiltrated water was visually observed and the initial process of soil infiltration was estimated. The specially constructed ring could be disassembled into two halves so as to conveniently observe the distribution of the infiltrated water. The detailed structure of the special designed ring and its application methodologies were detailed. An infiltration ring made of plexiglass was used to comparatively observe the 1-D infiltration process with refilled soil of the same density. The diameter of the disassemble ring was 35 cm, as the standard. A series of infiltration experiments were conducted with silt loam taken from Beijing. The experiment involved three soil bulk densities, 1.2 g/cm3, 1.3 g/cm3, and 1.4 g/cm3 and three hammering energy levels, determined by the weights of hammers of 1 kg, 2 kg, 4 kg, freely falling down from 1 m height. Two liters of water were used for the observations in every experiment, with two replicates. The wetted soil volume in the ring showed that the actually wetted soil column by the infiltrated water consisted of the radial/horizontal infiltration caused by the gaps between the ring wall and soil and the vertical infiltration from the ground surface. The preferential flow between the ring wall and the soil significantly influenced the accuracy of the measured infiltration rate. The errors increased with the increase of soil bulk density. The observed initial infiltration, in terms of the radial infiltration width and the vertical infiltration depth was approximately equal. The depth of vertical infiltration was 1.001 times of radial infiltration width. The initial infiltration rate measured was 3.3 times of the simulated 1-D initial infiltration rate. This study will supply a method for assessing soil infiltration rate measured by ring infiltrometer.

Abstract:Based on the sample data of agricultural soil profile, the locally-developed pedo-transfer function (PTF) of agricultural soil saturated hydraulic conductivity (Ks) in Daxing district was established using multiple regression with the independent variables, including constant and the monomials with variables of Si content, Cl content, and organic matter content. The PTF was validated simultaneously using multi-fold cross-validation method. The performance of Daxing District PTF built in this paper was compared with other three existing PTFs in predicting Ks. The PTF from this study was used in regional prediction of Ks in depth of 0~80 cm. The results showed that the root-mean-square error, average absolute relative error, and coefficient of determination of multiple regression function for predicting Ks in depth of 0~100 cm were 40.525 cm/d, 204.738%, 0.544, respectively, which were much lower than that of other three PTFs. The Ks was of great spatial variability in the top layer soil of 0~20 cm, and was relative small along the Yongding River in the north and southwest of Daxing district. The PTF from this study also performed well in the characterization of layered Cl loam in depth of 60~80 cm in Caiyu. It can be used in regional evaluation of Ks in Daxing district.

Abstract:A 0-1 programming model was proposed to optimize the deficit irrigation schedule. It is based on the concept of field water balance and the crop water production function, and introduces a 0-1 variable to describe the irrigation decision in possible irrigation periods. Microsoft Excel solver is applied for finding the solution. This model was applied in the irrigation schedule optimization of winter wheat in Xiaohe irrigation district in Shanxi Province. The result compares well with a previous developed simulation based optimization model, while the present model is much simpler in the solving procedure. Results demonstrate that the key period for winter wheat irrigation is the later jointing stage in early May. If the initial soil water content is low, the suitable irrigation time should be earlier in order to achieve higher crop yield. The evapotranspiration and relative crop yield increase with the irrigation volume, while the marginal yield decreases with the irrigation volume.

Abstract:Saline water irrigation is one of the effective measures for relieving the crisis of agricultural water utilization. Sand and saline-alkali soils were selected and were added with hydrophobic materials. CaCl2 solution with mineral degrees of 0, 1, 3 and 6 g/L were used for laboratory column infiltration experiments, in order to compare the effects of irrigation water quality on the distributions of soil water, soil salt and soil water repellency. The results showed that the curves of cumulative infiltration, wetting front and infiltration rate for sand 1 and wettable saline-alkali soil were all smooth after saline water irrigation. But those for sand 2 and hydrophobic saline-alkali soil were not so smooth, and their infiltration process were much slower than those of sand 1 and wettable saline-alkali soil. The increase of irrigation water mineral degree affected the infiltration process of saline-alkali soil more than that of sand. Philip model and Kostiakov equation were both good for fitting the infiltration curves of wettable soils. After saline water irrigation, the water drop penetration time (WDPT) along the profile increased both for sand 1 and san 2, but the maximal increment was only 3.6 s. The increment of WDPT for saline-alkali soil was obvious and the maximal increment value was 19 s. The increase of irrigation mineral degrees affected electrical conductivity, concentration of Ca2+ and concengtration of Cl-. In conclusion, this study indicated that saline water irrigation affected not only the distributions of soil water and salt, but also that of hydrophobicity.

Abstract:Long-term fertilization has a significant impact on soil organic carbon (SOC) stock. However, fertilization impact on physical fractions of SOC is still poorly understood on sloping upland of purple soil in the central Sichuan Basin, southwestern China. Therefore, this study assessed the impact of long-term different fertilization on soil aggregates distribution and its organic carbon factions under an intensive wheat (Triticum Aestivium L.)-maize (Zea mays L.) cropping system through four fertilization treatments, no fertilizer (CK), applied mineral fertilizer (NPK), pig manure matched with mineral fertilizer (OMNPK), and crop straw residue matched with mineral fertilizer (RSDNPK). Soil samples from 0～20 cm soil layer were separated into four soil aggregations (>2 mm large macroaggregates-LM, 0.25～2 mm small macroaggregates-SM, <0.25 mm microaggregates-M and <0.053 mm slit-clay microaggregates-SC) by using wet sieving method. LM and SM were further separated into particulate organic matter (POM), microaggregates (mM) and the silt-plus-clay fraction (SC). The results showed that the mass percent, organic carbon content and contribution of LM and SM under organic amendments combined with mineral fertilizer (OMNPK and RSDNPK) were significantly increased compared with NPK treatment, indicating that SOC was enriching towards larger soil aggregates under long-term application of organic fertilizer. Furthermore, organic carbon content and storage of POM, mM and SC in large aggregates were significantly enhanced by OMNPK and RSDNPK treatment. In comparison with NPK treatment, OMNPK and RSDNPK treatments significantly increased contributions of POM while decreased contribution of SC in large soil aggregates. The results also showed that it was greatly helpful to enhance POM sequestration and accumulation in large aggregates by long-term application of organic fertilizer. Additionally, the soil organic carbon storage in the whole soil and larger aggregates were dominated by SC fraction, which was helpful to enhance organic carbon sequestration, especially for crop straw return practice on sloping upland of purple soil.

Abstract:The effects of equivalence ratio (RER) and steam/biomass (S/B) ratio on gasification performances such as temperature distribution, gas composition and gasification stability were investigated in a pilot-scale fluidized bed gasifier with different feedstocks (sawdust, rice husk, wood pellet and straw pellet). The results showed that typical product gas percentage components from gasification were as follows: H2 27.1%～30.4%, CO 29.7%～32.6%, CO2 25.3%～27.9%, CH4 4.9%～5.8%. The uniformity of temperature distribution increased with RER and S/B ratio. More uniform temperature distribution was obtained in the case of sawdust and rice husk gasification. In the downstream direction of the dense phase zone, H2 and CO increased significantly whereas CO2 and O2 decreased considerably. In the dilute phase zone, the components of product gas varted slightly. Increasing the moisture content of sawdust will deteriorate the gasification stability. An abrupt increase of temperature in the bottom of gasifier was observed during the rice husk gasification. A consistent increase of temperature drop and pressure drop was observed in the dense phase zone in the case of wood pellet and straw pellet gasification.

Abstract:Microwave irradiation was employed as pretreatment for rice straw. The effects of microwave on enzymatic saccarification and lignocellulosic structure of rice straw, as well as its adsorption ability of enzyme, were investigated under the optimal conditions of pretreatment. The chemical composition analysis and structural properties determination by Fourier transform infrared spectroscopy and atomic force microscopy further confirmed that microwave pretreatment could disrupt the silicified waxy surface, break down lignin-hemicellulose complex and partially remove silicon and lignin, which could be favorable for the enhancement of enzymatic saccharification of rice straw and reduction of its adsorption of enzymes. However, X-ray diffraction analysis revealed that microwave irradiation had no significant influence on crystalline structure of cellulose.

Abstract:It can provide a theoretical basis for quantitatively analyzing the force on mechanism and energy consumption to build model of material molding process for vertical circular mould straw briquetting machine. On the basis of analysis on structure and working principle of core work unit on vertical circular mould straw briquetting machine, the models of forces on roller and molding energy consumption are established, and the load distribution curves and molding energy consumption curves are drawn under different technical parameters, and finally, the optimization method of technical parameters is proposed. Theoretical analysis results show that the eccentric design of molding hole can improve load distribution of the rollers, and reduce the energy consumption per ton of material. The eccentric angle of molding hole is related to the friction coefficient between equipment and materials as well as diameter ratio of roller to circular mould. The optimal eccentric angle of molding hole is greater when the friction coefficient between equipment and materials and diameter ratio of roller to circular mould are greater. The eccentric design of molding hole can reduce energy consumption from 0.29% to 3.58%. Finally, through the device comparison test, the above conclusions are confirmed. The research provides a theoretical reference for the design of key technical parameters.

Abstract:The mixed culture of photosynthetic bacterial was screened from activated sludge to carry out the experiment of hydrogen production. The effect of different nitrogen sources on the growth and hydrogen production of photosynthetic bacteria was studied, and the utilization pattern of nitrogen source in the process of hydrogen production by photosynthetic bacterial was also analysed. The results showed that: the photosynthetic bacteria had a significant selectivity in the process of growth to utilize nitrogen source. Inorganic nitrogen sources, especially ammonium salts was the most vulnerable to be used by photosynthetic bacteria, and organic nitrogen sources followed. Using (NH4)2SO4 as nitrogen source for growth, the best added concentration was obtined, which was 7 mmol/L. The maximum utilization appeared in 24~48 h of cultivated time, and the top consumption rate was 0.105 mmol/L. The impact of different nitrogen type on photosynthetic hydrogen production was not significant and the organic nitrogen was slighely better than inorganic nitrogen. When photosynthetic bacteria utilized (NH4)2SO4 as nitrogen source for hydrogen production and the added concentration was set as 3.5 mmol/L, the photosynthetic bacteria showed better activity of hydrogen production. The nitrogen source was only consumed during 0~48 h in the process of hydrogen production, and the cell no longer utilized the nitrogen source once the cell went into the period of hydrogen-producing peak.

Abstract:To improve detection precision and reliability of the porosimeter for particle materials, a constant volume porosimeter and an automatic control system were developed based on the ideal gas state equation and gas displacement method. In 0.1~0.4 MPa, the results showed that the higher the inflation pressure, the better the repeatability and precision of porosimeter when stainless steel balls, prisms, pebbles and fine stones were used in the test. The equation of error compensation was proposed through the calibration experiment using standard stainless steel balls and cylinders in the standard condition. The porosity of the samples were 16.02%, 25.14%, 35.57%, 49.05%, 58.42%, 67.79%, 76.57%, 85.36%, 94.14% respectively. In the inflation pressure limit of 0.4 MPa, with 13.5% wet basis of paddy porosity, the test results showed that the range of porosity was 0.3%, when filling rates of sample were 25%,50%,75%,100% respectively. The reliability of measurement was proved by the results.

Abstract:A new type of capacitive grain moisture on-line measuring device was designed based on the measuring principle of non-contact parallel plate floating capacitor, which was suitable to continuous dryer under severe environment. The static batching measurement was used to improve the repeated accuracy of the measurement. Positioned filling device was designed to eliminate the measuring error caused by the variation of porosity and different way of filling. Wireless communication technology was adopted to achieve real-time data transmission from client sensors to computer and overcome the poor drying conditions, which could affect data transmission. The relationship among moisture, temperature, and capacitance of corn was calibrated and the system was tested on a continuous dryer. The results showed that the correlation coefficient between results of oven method and results of online measuring system was 0.992, and the absolute error of measurement was less than ±0.4%, while the working temperature was 15~50℃, relative humidity was 80%~100%, drying temperature was 70℃, and the corn moisture content range was 14%~21%. It proved that the online measuring system meet the design requirement of poor drying conditions.

Abstract:Multi-objective fuzzy matter element method was put forward to optimize the sensor quantity. Fuzzy matter element matrix was constructed by means of center effect measure, and the monitoring point was optimized according to the comprehensive correlative degree. Twenty-seven sensors was reduced to 7 in the refrigerator car, which reduced the costs of cold-chain transportation. The statistical analysis method and the temperature field analysis were applied to validate the rationality of the optimization algorithm. The measurement data of sensors had more than 95% of confidence level and the similarity rate of temperature field distribution between before and after optimization reached over 90%, which achieved the dual requirements of cost savings and accurate monitoring in cold chain transportation.

Abstract:Total water content is an important quality attribute for consumer satisfaction, and a more accurate pre-detecting method is necessary. The conventional method of partial least squares regression (PLSR) has been widely used in meat water content forecasting. In this study, the cluster analysis of particle swarm optimization algorithm was carried out and calibrated as one of the optimization methods of PLSR with the goal of reducing computation complexity and enhancing the prediction precision. Based on the novel method above, a predicting model of beef water content was developed in wavelength range of 900~2 300 nm, and the best predicting result with Rc=0.920 5 and Rv=0.919 1 was obtained in wavebands of 900~1 400 nm. The samples used in the experiment were beef longissimus collected from the supermarket in that day, and the water contents of samples were detected according to the national standard. Spectra of samples were acquired in reflectance spectral detection system and pre-treated procedure was carried out by means of multiplication scatter correlation method before model construction.

Abstract:The effect of hypobaric storage under different pressures on the energy metabolism of juicy peach fruit were studied. The pressures were controlled at (10±5) kPa and (80±5) kPa, respectively with air storage as control. Contents of ATP, ADP, AMP and energy charge, and the activities of mitochondria respiratory metabolism-related enzyme H+-ATPase, Ca2+-ATPase, succinic dehydrogenase (SDH), cytochrome C oxidase (CCO) were determined during storage. The results indicated that the hypobaric storage significantly maintained higher H+-ATPase, Ca2+-ATPase, SDH and CCO activities, and inhibited the decreases of contents of ATP and energy charge level. Hypobaric storage under (10±5) kPa pressure was more conducive to maintain energy level and the activities of mitochondria respiratory metabolism-related enzyme. These results suggested that the benefits of hypobaric storage associated with energy metabolism.

Abstract:In order to explore suitable quick-frozen preprocessing techniques of hami melon (Cucumis melo var. saccharinus), hot water blanching (temperature 80℃, 90℃, 100℃; time 0.5~4 min), 100℃ steam blanching ( time 0.5~4 min ) and high pressure processing ( pressure 100 MPa, 200 MPa, 300 MPa; time 1~9 min) were adopted to study the effect of different preprocessing ways on quality of hami melon. Futhermore, the effect of hardness maintenance in different concentrations of CaCl2 solution was evaluated. The polyphenol oxidase (PPO) and peroxidase (POD) activity of hami melon extract was inhibited effectively by hot water blanching, while the hardness and vitamin C content decreased significantly with increasing temperature and time of blanching. High pressure processing at 100~300 MPa could barely suppress PPO and POD activity of hami melon, and under certain conditions the enzyme activity was even activated, meanwhile the texture was seriously damaged. Vitamin C content also decreased significantly. However, 100℃ steam blanching inhibited PPO and POD activity effectively and also performed better than hot water blanching and high pressure processing in keeping hami melon texture and vitamin C. Therefore, 100℃ steam blanching at 1 min was chosen to preprocess hami melon, and in this condition PPO and POD residual activity levels were 55.5% and 46.0% respectively. Compared with the fresh hami melon, hardness maintained 80% and vitamin C lost only 13%. On this basis, soaking in 1.0% (m/m) CaCl2 solution improved hami melon hardness and vitamin C content by 7.6% and 6.8%, respectively.

Abstract:This study presents a new impregnation technique for brining four kinds of vegetables based on Na+ and Cl- ion current generated by the electromagnetic induction. Saline concentration, processing time and porosity were identified as main variables, which influenced pickling efficiency. Based on the principle of Box-Benhnken central composite design, response surface analysis was applied to obtain the regression model to estimate the salt content of vegetables in the porosity range from 5.4%~8.2%. The results showed that the efficiency of magnetic energy converting to electrical energy increased along with increasing the concentration of solution. With a thickness of 24 mm and a porosity of more than 6% of the vegetables tissue, the sample were immersed in saline solutions subjected to ion current under the influence of the static magnetic field for 30 min, the salt content reached 5% approximately. The regression model provided reliable prediction of the salt content in eggplant with the porosity of 7.3%.

Abstract:The information of individual animal husbandry mainly includes estrus information, delivery information, behavior information, weight information and health information. Automatic and intensive farming is the development trend of husbandry, and accurately and efficiently monitoring individual animal information is useful for analyzing animal physiology, health and welfare, and the foundation of automated health farming and meat traceability. At present, the method of monitoring the information of individual animal husbandry in China mainly relies on the artificial observation, which has the shortage of strong subjectivity and time-consuming. The present study and application of some key technologies, including estrus information, delivery information, behavior information, weight information and health information, and monitoring of the animal husbandry information, are discussed. The research direction of the intelligent technology for individual animal husbandry information monitoring in the future is put forward.

Abstract:Using the object-oriented JAVA language, a WebGIS-based system for evaluating the technical efficiency of broiler production was designed and developed. The system had multiple functions including the collection and storage of broiler breeding data (spatial and attribute data), calculation of technical efficiency, analysis of time spatial characteristics, analysis of the determinants of technical efficiency and visual displays of the evaluation results. The application of the system shows that it can provide a simple, rapid and comprehensive information query function, and serves as an intelligent and integrative tool for management of spatial data and the evaluation of dynamic technical efficiency and determinants.

Abstract:A real-time video capturing system for dairy was designed, and a detection method of breathing rate and abnormity in cows was studied based on the system to acquire the information in breathing. The optical flow method was used to calculate the velocity for each pixel. Breathing points were found out by looping Otsu operation according to the magnitude of velocity. The period was calculated from the curve of direction of velocity to get the breathing rate, and breathing abnormity was detected according the duration of each breath. 72 cows were detected for total 360 minutes to test the methods. The results demonstrated that the accuracy of calculated breathing rate and the recognition ratio of breathing abnormity were 95.68% and 89.06%, respectively, and the error detection of breathing abnormity was 2.53 times per-minute.

Abstract:For deploying a wireless sensor network system and studying the channel characteristics in tomato greenhouse, relationships among radio frequency signal propagation characteristics and communication distances, antenna heights, transmission paths were studied with a 2.4 GHz carrier frequency for configuring wireless sensor network in a tomato greenhouse. The results showed that the attenuation of the received signal strength caused by communication distance accorded with a logarithmic model. When the height was fixed, the strength index of received signal tended to decrease and the packet loss rate fluctuated as the distance of transmitter to receiver increased, which was an overall increasing trend. It was the best to place the antennas at a column of central location in greenhouse, in the top of the tomato or above of it, followed at higher place above 1.5 m. The regression analysis results demonstrated that there was a quadratic relationship between the regression parameter A and the antenna height, and there was also a quadratic regression equation between the environmental factor n and antenna height. Besides, a model used for calculating the received signal strength of 2.4 GHz transmitting through tomato greenhouse was constructed. Validation results showed that the model could better predict the received signal strength at different distance point at different height. This research can provide a reference for WSNs application.

Abstract:The improved LevenbergMarquardt algorithm was used to estimate the parameters of poplar branch and trunk modeling. To achieve a dynamic three-dimensional visualization of poplar, amount of diameters were obtained by measuring different poplars forest age. According to the growth trend of diameters, the function of diameter growth was built using the improved LevenbergMarquardt algorithm. A class of heart-shaped curve equation was proposed, and the relationship function between the main branch length and the depth of the sticks was obtained using the improved Levenberg-Marquardt algorithm. A lot of comparison experiments were carried out, and the results demonstrated that the fitting algorithms and mathematical models selected could better simulate the growth of poplar branches. The three-dimensional visualization of poplar was realized with dynamic simulation equation, and the results validated the effectiveness of poplar growth modeling.

Abstract:In order to realize the automated estimation of orchard yield, we studied on the recognition method of green apple based on machine vision. An image capturing system composed of a color camera and an active lighting system was used to capture images of apple trees at night. A hybrid classifier including an SVM method based on the advantage of H, S and normalized g and a Super-G method was developed to remove the background. The connected apples were found by the area feature and the ratio of major axis to minor axis of the individual regions. Then we used the Euclidean distance transformation method to generate the distance image of the founded connected apple regions. Finally a watershed method was used to separate the connected apples, and the total number of the apples in image were known. The analysis of experimental results regarding 64 images showed that the average rate of correct recognition was 89.30%.

Abstract:The object of this study was to seek a new way to detect the phosphorus levels of tomato rapidly. Taking the tomato grown under different phosphorus levels as the object of the research, SEM (Scanning Electron Microscope) and TEM(Transmission Electron Microscope) were adopted to evaluate the effects of phosphorus levels on micro-structure and ultra-structure of tomato leaf. The results showed that for the control treatment plant ,the thickness of leaf was (124±2.14) μm, the stomatal and trichome density was (233.0±5.5) mm-2 and (34.2±1.33) mm-2 respectively, the height of trichomes was (97.0±2.83) μm, and the size of the stoma was 13.91±0.85 μm. In comparison with the control treatment, the thickness of leave, the density of stomata, the density and the height of trichomes decreased significantly in response to low phosphorus levels, while the changes in stomata size were not significant. The size of stomata, the density of trichomes, the number of vascular bundle were increased in high phosphorus level plants, while the density of stomata, the length of trichomes did not change markedly. At the ultra-structural level, low phosphorus supplied cell contained chloroplast so that it had begun to lose their structural integrity, and high phosphorus supplied cell had thicker cell wall, but the structure did not change observably. Based on the results, a new method to detect phosphorus levels rapidly was proposed.

Abstract:To realize precise and non-destructive determination on moisture content of plant leaves, a moisture detector based on leaf capacitance was designed. Circular parallel plate capacitor was used to detect capacitance values of plant leaves, FSR402 pressure sensor was used to detect pressure on plant leaves given by circular parallel plates, and MSP430 single-chip microcomputer was used as micro-controller. Maize leaves were used as samples to study the influence of moisture content and pressure on obtained capacitance values, and the best pressure for maize leaves’ capacitance determination was obtained. The model describing the relationship between capacitance and moisture content of maize leaves at the best pressure was established and verified. The results showed that the capacitance values of maize leaves increased with moisture content and pressure. The best pressure for obtaining capacitance values of maize leaves was 4 N. The running test indicated that the absolute measurement error of the designed detector for moisture content of maize leaves was -1.2%~1.7% in wet basis when the moisture content was between 55% and 80%, and the response time was within 3 s at oscillation frequency of 8 MHz.

Abstract:Regarding to the inadequacy of traditional soil nutrition detecting techniques, a new soil nutrition on-line detecting equipment based on laser induced breakdown spectroscopy theory is developed. The experiments to analyze feasibility and accuracy of detecting soil potassium nutrient content is carried out with this equipment. Experimental results show that characteristic lines of potassium are 766.49 nm and 769.90 nm respectively, and the relationship of soil potassium nutrient content and characteristic peak value is positive correlation. However, once potassium content in samples is above 0.3%, the relationship of potassium nutrient content and characteristic spectral intensity becomes nonlinear because of the existence of emission spectrum self-absorption phenomenon. To eliminate the detecting matrix effects, lithium element in soil samples is selected to be a internal standard element for correcting potassium element characteristic lines. Using spectral intensity of sensitive characteristic wavelength 766.49 nm and 769.90 nm to estimate soil potassium nutrient content by binary linear model, the determination coefficient (R2) of model reaches 0.933 7, and the relative root mean square error(RRMSE) is only 0.276 1. With current testing conditions, the lowest detection limit of soil potassium content is 212 μg/g. This result indicates that the detecting system can satisfy the requirements of soil potassium nutrient on-line detection preliminarily, but needs to be further improved.

Abstract:An important part in farmland quality evaluation is summarizing the county-level results into provincial result. As the foundation of the national summary, the summary accuracy directly affects the distribution of the national farmland land quality. Because of the summary base map lags behind, a method was proposed for quickly updating summary base map. Meanwhile, the multiple attribute constraint and nearest-neighbour provincial summary method for farmland quality database was proposed, then the summary software was developed for automating provincial summary. Daxing district of Beijing was taken as an example, then the rationality of summary base map process was analyzed and the distribution of farmland land quality before and after summarizing was compared by the standard distance, mean center and standard deviation ellipse indexes. Results showed that except grade 16, the standard distance reduced after summarizing, which meant that the summary result was more gathered than the county level and the process of summary base map was reasonable. Furthermore, by comparing the mean centre and the directional distribution before and after summarizing, the distribution of farmland quality almost had no change, which indicated that the spatial distributions of the province and county farmland quality were in highly consistent.

Abstract:This paper addresses the synthesis problem of Watt-I six-bar linkage motion generation, and introduces a novel and convenient synthesis approach. The coupler link used as end-effector of Watt-I is connected to a coupler plane of a four-bar linkage, so that the designers need to give the task positions of these two coupler planes. With the method, a four-bar linkage is synthesized firstly, and then a dyad is attached to this four-bar linkage to obtain a six-bar linkage. For four-precision-position problems, four-bar motion generation can produce infinite number of solutions. And for any selected four-bar linkage, we can present an equation of pivot curve that each point on this curve can generate a satisfactory dyad. Based on the planar solution region of four-bar linkage, an infinite number of synthesized six-bar linkage solution can be expressed in a finite spatial region. In addition, the paper still puts forward a circuit and branch defects distinguish method for Watt-I six-bar linkage. The feasible spatial mechanism solution regions without any defects are obtained by using the distinguish method. Application of the spatial solution regions makes designers to be able to understand the information of the synthesized six-bar linkages on the whole, and makes it possible to get the optimal solution that attached more design requirements.

Abstract:Considering the limitation of the DH rule when using it to establish coordinate systems for robots, an auxiliary coordinate method was proposed as the extension of the traditional DH rule. The details about how to construct the auxiliary coordinate and how to use the auxiliary coordinate method were stated comprehensively. By the proposed method, any point of a link, not exactly in the joint of two links as usual, can be chosen as the original point of the auxiliary coordinates. The analytical results based on the auxiliary coordinate method were compared with the numerical simulation and it was found that they were in good agreement. It is shown that the method presented is more accurate and flexible when applied to complex robot systems while one or more components are not straight link, for example in L-shape, or t a relative rotation of one link about the axis of the connected previous one.

Abstract:The concept of the couple hydraulic motor is put forward, which is different from the traditional hydraulic motor. Based on the principle of the multi-acting double-stators couple hydraulic motor, the theoretical torque is studied. Through analyzing the pulsating characterize and the influencing factors of the motor, the relationship between the pulsation and the numbers of sliders is obtained. When the number of the rollers and connecting rods equals to 8 or less, the torque pulsation of the hydraulic motor consisted of the even number of the rollers and connecting rods is lower than what number is odd. When the number of the rollers and connecting rods equals to 9 or more, the torque pulsation of the hydraulic motor consisted of the odd number of the rollers and connecting rods is lower than what number is even. Finally, a theoretical basis is provided for the design and experiment of the hydraulic motor.

Abstract:Clearance leakage is the main cause of pump leakage. Aiming at the design and control of the key clearance, which determines the performance of screw pump such as clearance of barrel wall and meshing area, the model of differential pressure flow and shear flow of clearance leakage in pump cavity is established. The mathematical expressions of leakage from different clearance are obtained by analyzing the clearance leakage of barrel wall and meshing area. The influence of the rotation speed and pressure difference between inlet and outlet on flow characteristics and volumetric efficiency characteristics of screw pump is revealed by theoretical calculation and experimental analysis of twin screw pump. Based on these results, the rotor design theory of the screw pump as well as the performance of the screw pump can be improved.

Abstract:The electro-hydraulic position control system, which has the shortcomings of highly nonlinear, time-varying of the internal parameters and disturbance of the external load, seriously affects the static and dynamic control. In order to solve this problem, a compound control strategy combining load compensation with ADRC (auto disturbance rejection controller) was put forward, and the working principle of the composite control strategy was given in this paper. ADRC controller was designed, and the extended state observer was used for observing internal parameters uncertainties and external disturbances, so that the disturbance of the system is suppressed effectively. Load compensation controllerwas designed and the compensation model was derived.They further weakened the adverse effects on the system due to the changes in the external load, and improved the position control accuracy of the system. The composite control strategy was verified on the simulation in Matlab and semi-physical simulation platform, respectively. And the simulation and experimental results show that the electro-hydraulic position control system with ADRC controller could effectively inhibit the interference of external disturbances, and the precise positioning control was realized after introducing the load compensation controller. And then the efficiency of the method presented was verified through simulations.

Abstract:A calculation model of jet hole arrangement ways was established based on the characteristics of single jet hole. With SST kω turbulence model, the drag reduction characteristics of jet surface under the condition of different jet hole arrangement was researched by using the numerical simulation. Then, the impact of jet hole arrangement on surface viscous resistance and drag reduction rate was analyzed, and the maximum drag reduction rate reached 33.65%, which was experimentally validated by using numerical calculation model. The movement characteristics and distribution rules of the shear stress of wall boundary layer, the surface compressive stress, the flow velocity and vortex generating in the downstream of the jet hole were studied. The results showed that wall boundary layer could be well controlled by jet hole arrangement of jet surface, and the drag reduction mechanism of jet surface was also revealed.