Abstract:In order to improve the navigation accuracy and control precision, some related study on the autonomous navigation of agricultural robot control was carried out. Firstly, the Sage_Husa self-adaptive filtering and strong tracking Kalman filtering were introduced. The former has the characteristics of high precision but huge computation, the latter has strong adaptive capacity, but the filtering accuracy is low. So combined the advantage of these two filtering algorithms and used the strict convergence criterion, an improved self-adaptive Kalman filtering algorithm was proposed. This filtering algorithm can effectively reduce the state error of system, restrain the signal divergence, so it can guarantee the real-time and stability of the system, and has better filtering convergence and precision. By the simulation experiment, the results show that the proposed filtering algorithm was flexible and reliable. Secondly, in order to prevent the PID controller integral saturation phenomenon, the method of variable structure switch was introduced, and the variable structure PID (VSPID) controller was proposed. By the simulation experiment, the results show that the VSPID can quickly withdrew from the saturation state, and it can quickly reach the expectations and maintain this state. The problem of controller supersaturated was solved effectively. It can greatly improve the control efficiency, and maintain the good tracking performance. Thirdly, combining the improved self-adaptive filtering with anti-windup VSPID controller, the stability and precision of navigation system was improved. The results of simulation experiment show that proposed method makes the system quickly withdrew from the saturated zone, and with a better tracking performance. Finally, the proposed method was applied to the mobile robot navigation system and the field experiments on the school playground. The experimental results show that the proposed method can improve GPS positioning precision and enhance the antiinterference capability, after further adjusting parameters and tracking the given path reaches the desired effect. It demonstrates that the proposed method greatly improves the capability of restraining filtering divergence, anti-interference and control precision.

Abstract:A method for calculating navigation parameters via RTK— DGPS fusing inertial sensor was proposed in order to improve the navigation precision of agricultural vehicle. The key for calculating the lateral deviation was the compensation of the lever-arm effect error via the geometric transformation with the attitude angles form the inertial sensor. Test results showed that the mean error compensated by this method was 0.08m when the pitch and roll was existed. Benefit from the compensation, we got more accurate lateral deviation by the enhanced positioning accuracy. The error of the heading deviation calculated by the inertial sensor will be larger when there is magnetic interference around the working environment. Therefore, another method to calculate the heading deviation was proposed, which is using least-square method to fit the travel path with the dynamic positioning points measured by RTK—DGPS. Test results showed that when the vehicle was steered along a straight line, a circle and a curve, the mean errors were 0.9636°, 3.6418°and 2.7562° between two methods which were measured and calculated by RTK—DGPS and the inertial sensor. So it was proved that the heading deviation could be calculated by RTK—DGPS effectively. Two methods can enhance the adaptability of the system, the heading deviation can be got by RTK—DGPS instead of the inertial sensor under the environment with magnetic interference.

Abstract:Orchard vehicle is not only a modernized orchard management platform, but also a fruit-transit station. Its lifting platform can reconcile the needs of working on the ground and in the air to meet all kinds of actual requirements. But working conditions in orchard are complicated (like uneven and rolling ground) and the lifting platform has a relatively high mass center and a changing load, which are easy to cause rollover and pitch accidents. Aiming at the high frequency of vehicle rollover accident and the serious consequence it may bring about, this paper first developed two simplified linear dynamic models to analyze the force situation in rollover and pitch, then an orchard vehicle active steering control model was established based on dynamic orchard vehicle model and tyre model. After that, in Matlab/SimMechanics modular, applying control law, the orchard vehicle body model, tyre model, ground model and control model were constructed individually, and combining all the models with the orchard vehicle active steering PID simulation control model. Finally, comparative experiments of scaled orchard vehicle model and simulation analysis model were conducted to validate the practicability of Matlab/SimMechanics simulation model. Results show the SimMechanics model is sufficiently realistic to simulate the vehicle’s motion and the control law is capable to enhance the stability of orchard management platform, which provides references for follow-on study on stability control of orchard vehicle.

Abstract:In order to accurately track Ochotona curzoniae in natural habitat environment, an object tracking method based on Meanshift algorithm was proposed. Considering the object tracking method of kernel Meanshift algorithm based on RGB color histogram usually has the deformation of inaccurate tracking or lose of target in the scenario that the color is similar between the background and the object. In view of the problem that the color between the Ochotona curzoniae and the background is similar in the object tracking process in natural habitat environment, a visual descriptor named as the local texture difference operator (LTDC) was proposed to reflect the subtle differences between the Ochotona curzoniae and background. The LTDC operator was combined with color information to characterize the object model and the object model was embedded into the Meanshift tracking framework for the object tracking of Ochotona curzoniae. The experimental results show that the proposed method for characterizing the object has a strong difference ability of target and background. The object can be accurately positioned in the color similar scenario of the object and the background. Compared with the FLBP algorithm, the average iteration number of proposed method is 79.04% of the average iteration number of the FLBP algorithm, the average tracking total time of proposed method is 8235% of the average tracking total time of the FLBP algorithm, the average tracking speed of proposed method is 1.22 times of the average tracking speed of the FLBP algorithm.

Abstract:This variable rate fertilizer applicator based on crop canopy real-time spectral information (normalized differential vegetation index) was designed to realize real-time variable fertilization in the field. By accessing the real-time normalized differential vegetation index via six spectrum sensors, and the speed of the tractor via velocitymeasuring system, the expert system of applicator could ascertain the rate of fertilizer based on the fertilization algorithm. The expert system of applicator adjusted fertilizing to attain precision fertilization according to the feedback fertilizer flow. The system design, working principle and experiments of the applicator were explained. The experimental results indicated that the inherent spatial variability of wheat growth within a field was considerable, and wheat canopy normalized differential vegetation index could resolve this difference. The fertilization precision could reach above 90%, and variable rate fertilizer applied more nitrogen (28kg/hm2) than quantitative fertilization. Therefore, the control system of the rate fertilizer applicator was favorable, and the applicator could achieve precise fertilization in the precision agriculture.

Abstract:The seeds often suck on the sucking hole when the sucking plate rotates. The area between the sucked seeds and sucking hole is smaller than the area between the normal sucked seeds and sucking hole, which leaded to a shortage of suction. As the suction is less than a sum of external forces, sucked seeds will be separated from the seed sucking hole and do a parabolic movement with a particular velocity. This phenomenon is called “early dropping seeds”. To avoid this and increase the stability of seed sowing and the performance of hill formation of rice pneumatic metering device, a shield device was designed. Shield device was fixed on seed chamber shell through bolted connections. It was able to stop the seeds flying to the second half of sucking process after the parabolic movement drove by “early dropping seeds”. Indic hybrid peizataifeng was taken as research subjects, of which the water content was 21.1%. “Early dropping seeds” phenomenon was observed by means of high-speed photography technology, which enabled moving process of sucked seed to be clearly photographed. The probability of “early dropping seeds” was studied by using multi-factor experiment under different negative pressures for seeds sucked, rotation rates and shield device. Precision of seed metering was also counted, as shield devices were installed on the metering device. The experimental results showed the “early dropping seeds” phenomenon and precision of seed metering were improved with a shield device. The optimized condition was that the sucking plate rotation speeds of 25~40r/min and the negative pressure for seeds sucked of 1.6kPa. The probability of 1~3 seeds was 93%~97%. In the experiment, a shield device on the metering device could control the “early dropping seeds”, and improve the stability of seed sowing and the performance of hill formation.

Abstract:With the aim to realize feeding seedlings stably, accurately and quickly, this paper introduces a feeding-seedling device for the high-speed feeding-seedling device for pot-seedling. This device reduces the moving distance of the seedling box when operating by using a periodic non-uniform lateral shift box. And with the proposed seedling vertical driving device, vertical seedling gains its accuracy and stability as well as high speed. The operational principle of the lateral feeding-seedling device was firstly elaborated, followed by its structure design. Secondly, working principle of the seedling vertical driving device was analyzed and its kinematics model was established. Then a set of feasible parameters was obtained by Matlab and applied in the following device design. Finally, a validation test was carried out. The test result indicates that the seedling box of the proposed lateral feeding-seedling device gains shorter distance when picking seedlings, with a 37% reduction from the traditional one. Moreover, this device achieves error within ±2mm in single feeding and without cumulative error. The proposed feeding-seedling device is able to support pot-seedling speed of 200~250 times/min.

Abstract:In order to get the best parameters of rotary seedling planting mechanism quickly and easily, this paper proposes the requirements of rotary seedling planting mechanism for prefect planting, such as kinematics (trajectory, pose and speed) characteristics of planting nozzle, geometrical characteristics of holes, avoidance of interference and convexity preservation of non-circular gears. According to these requirements, this paper establishes eleven subgoal functions of planting mechanism with planetary eccentric-elliptical gears. By using fuzzy theory, the multi-objective optimization problem was turned into a single objective optimization problem. Then, the parameters satisfied the above perfect requirements were got. According to the parameters which were obtained with optimization, this paper carries out structural design, virtual simulation, test bed machining and the experimental simulation of field planting. The result shows that this mechanism has high seedling erectness rate and the optimization model is correct. The proposed optimization model conquered the defect of trial and error that the simulation software has in the process of parameter design for planting mechanism, improved the optimization efficiency and reduced the demands for people who implement the optimization of parameters.

Abstract:In order to obtain a spatial planetary gear train with higher transmission ratio, which can shorten the large horizontal offset of picking seeding trajectory, a kind of special shaped non-circular bevel gears based on spherical curve was put forward, and a wide-narrow distance transplanting mechanism composed of special shaped non-circular bevel gears and crossed cylindrical gears was obtained. The pitch curve of special shaped non-circular bevel gears was designed by two non-uniform B-splines which had continuous angles and discontinuous radius. The gear pair could continuously and smoothly work after adjusting the height of tooth profile curve in the transition section of two non-uniform B-splines. The theoretical model of wide-narrow distance transplanting mechanism was built up. An optimization program was finished, and the effect of the different shape of special shaped non-circular bevel gears to the widenarrow distance planting trajectory was analyzed. A three-dimensional model was built up by computer, and an actual physical model was processed. The shapes and speeds of the planting trajectory which formed by the two models were compared, and the values of measuring parameters were almost the same. A test with seeding by transplanting mechanism was carried out based on rotary trial soil bin. Speed comparison between the transplanting mechanism composed of special shaped non-circular bevel gears and transplanting mechanism composed of non-circular bevel gears was made, and the result showed that the wide-narrow distance transplanting mechanism composed of special shaped non-circular bevel gears had the advantages in shortening the large horizontal offset of picking seeding trajectory, and the planting trajectory was better.

Abstract:In order to solve the high loss and blockage problem of full-feeding combine harvester harvesting green stem and leafy rice which is difficult to thresh, a tangential-horizontal-horizontal threshing and separating device was developed. On the test bench of tangential-horizontal-horizontal threshing and separating device, the parameters of axial distance of concave fences, the number of cover and axis spacing of cylinders were preferred by using comparison test. The experiments showed that the preferred parameters were the axial distance of concave fences of 10mm, 16mm and 16mm, the number of cover of 4 and 4, and the axis spacing of cylinders of 645mm and 667.5mm. Under the preferred structural parameters, threshing and separating performance experiments using different feed rates, concave clearances and cylinder speeds were carried out on the test bench of tangential-horizontal-horizontal threshing and separating device. The preferred operating parameters were obtained by using fuzzy comprehensive evaluation method and variance analysis. The experiments showed that the preferred operating parameters within the test range were feed rate of 5kg/s, speeds of 550r/min, 600r/min, 750r/min and concave clearances of 40mm, 35mm, 40mm for the first tangential cylinder, the second horizontal cylinder and the third horizontal cylinder. The performance indicators were obtained under the above parameters: un-threshed rate of 0.05%, entrainment loss rate of 0.36%, the total loss rate of threshing 0.41%, power consumption of the first tangential cylinder, the second horizontal cylinder and the third horizontal cylinder were 3.33kW, 21.26kW and 12.58kW. The total power consumption was 37.17kW and the extractions impurity rate was 14.37%.

Abstract:The operating performance of combine harvester is not usually satisfactory because of the subjectivity of parameters design to the fuzzy control system of forward speed. Taking a combine harvester as research objective, the paper constructs the simulation model of multi-parameters fuzzy control system and establishes the optimized objective functions for control performance and harvesting performance to evaluate operating performance of combine harvester. A multi-objective genetic algorithm was used to optimize membership functions and parameters’ factors of conveyer trough, cutting table auger and tangential threshing rotor influenced on forward speed in the fuzzy control system. By comparing to the model simulation and analyzing the two groups of experimental data before and after optimization, the results proved that after the control system optimized, the control performance still presented good under the conditions of external interference, and the average unit loss indexes reduced from 1.45% and 1.26% to 1.12% and 1.14%, respectively. The feeding quantity did not change much, and the whole operating performance was improved.

Abstract:Agricultural machinery is the most important equipment and factor of agricultural production. To study main influencing factors of economic benefit and development strategies of agricultural mechanization in China based on vegetables mechanized production, this paper studies agricultural mechanization status and problems of vegetable production in typical region according to questionnaire survey and on-the-spot investigation, and analyzes vegetable cost-benefit based on statistical data from 1998 to 2012. The results show that selling price and labor cost are the main influencing factors on vegetables net profit per unit area, influencing factors range from higher to lower are as follows: selling price, labor cost, which demonstrates that improving vegetable market mechanisms by policy support is helpful to protect the plant benefits. It also shows that pesticide input and agricultural film input are the main influencing factors on vegetable yield, influencing factors range from higher to lower are as follows: pesticide input, agricultural film input. Input in agricultural mechanization is the main influencing factor on vegetable output value, which demonstrates that the marginal utility of chemical agriculture decreases gradually and agricultural machinery has been playing an increasingly prominent role. The main vegetable varieties are classified into greenhouse solanaceous vegetables, outdoor solanaceous vegetables, and outdoor leaf vegetables according to the input-output indicators. The mechanization needs urgent degrees range from higher to lower are as follows: outdoor solanaceous vegetables, greenhouse solanaceous vegetables and outdoor leaf vegetables. Vegetable comprehensive mechanization level is very low in China, which is different for different operation links, different regional conditions and different species. Meanwhile, policy input, extension system and technology innovation have significant impact on vegetable mechanization technology development. It is important to explore agricultural mechanization technology mode, which combines agricultural machinery with agronomy according to local conditions. The research is meaningful for raising lab productivity and reducing vegetable production cost using labor saving vegetable mechanization production technology.

Abstract:Based on the observation data, including net radiation flux, latent heat flux, sensible heat flux, soil heat flux, etc., which were surveyed at the stage of rice growth in 2013 at Kunshan Irrigation and Drainage Experiment Station with eddy covariance method, this article analyzes the features and distribution characteristics of energy balance components in the typical sunny day and cloudy day, as well as the diurnal and monthly variations of energy fluxes in rice season. The ratios of energy balance components to the net radiation and the energy closure degree of paddy field in different temporal scales were also discussed. The results illustrated that the monthly averaged diurnal variations of energy balance components, which were observed in typical sunny day in southern subtropical monsoon region at the stage of rice growth, obviously presented as the singlet trend of inverted “U” shape. The daily mean value and peak value of energy balance components in typical sunny day were smaller than that in cloudy day, but it also presented as the trend of singlet variation. The difference between latent heat flux and sensible heat flux appeared apparently. The ratios of the above two to the net radiation were anti-connected and the values were 86.2% and 0.8%, respectively. The ratio of the soil heat flux to the net radiation was 1.3%. As a result, the latent heat flux was the main component of net radiation in different temporal scales. Due to out-sync of energy transformation, turbulent fluxes lagged behind the net radiation about 0.5h, and the hysteresis of surface soil heat flux was about 1.5~2.5h. Energy balance components in different time spots were corresponding incompletely as to the impact to the short-term energy closure rate. But compared with other ecosystems, there was a better energy balance closure in water-saving irrigation paddy field, which suggested the flux data measured by eddy covariance method was capable to act as an effective judgment for evaluating the availability of energy flux features.

Abstract:With the purpose of evaluating the development degree of preferential flow under dry and wet farmland in Three Gorges Reservoir Area, the statistical sample variability analysis method and morphological image processing technology were used to analyze variability of the preferential flow areas in the field scale soil profile dyed images. The results showed that soil wetting front infiltration rate and soil dyeing image parameters, including wetting front infiltration rate, dye coverage, uniform infiltration depth, preferential flow fraction and length index, changed in the characterization development degree of preferential flow wet farmlands were higher than those of dry farmlands. The preferential flow evaluation method was proposed according to the comparison with soil dyeing image parameters. The same result showed the accuracy of preferential flow area dyed image variability analysis method to analyze the development degree of preferential flow. The new method is simpler than the others, and can improve the accuracy of the visual evaluation dyed images. It is also better to combine statistics and morphology to quantitatively analyze the development degree of soil preferential flow.

Abstract:The residual of plastic film in soil continuously increased with the large application of agricultural plastic film during the last few decades. It destroyed the soil structure and seriously influenced the migration of soil water movement and solute. Saturated hydraulic conductivity and soil water characteristic curve are very important parameters for evaluating infiltration properties and simulating soil water and solute. Five residual film treatments (0, 5,100,200,400kg/hm2) were conducted to study the effects of different amounts of residual film on soil water infiltration and soil water retention ability and also to analyze the influences of residual film on soil structure based on CT images. The results showed that saturated hydraulic conductivity was significantly exponentially decreased with increase of residual film (p<0.05). When residual film reached 200kg/hm2, the saturated hydraulic conductivity reduced to 12% of non-residual film treatment. However, the soil was easily dehydrated and water retention ability was lowered with increase of residual film under high suction condition (>100kPa). There were good relationships between suction and soil water based on either van Genuchten model or Gardner model, and the parameters showed regular variation with the increase of residual film. The threshold CT images showed that black spot area clearly increased with the increase of residual film, and there was proportional relation between black spot area and residual film amount. The black spot areas were 19 times than non-residual film treatment, and the residual film significantly increased in soil.

Abstract:The Hargreaves (HG）equation, McClound (M—C) equation, Makkink (M—K) equation and Priestley—Taylor (P—T) equation were amended against the FAO 56 Penman—Monteith（PM）by using the observed meteorological data from 1970 to 2011 at Xinxiang City. Then, the calibrated equation and weather forecast data were used to predict the 10d ET0. The precision of weather forecast and forecast ET0 was evaluated, and an analytical method was developed to translate daily weather forecast message into the variables needed by estimation ET0. The results showed that the mean accuracy of calibration HG (HG—M) equation, P—T equation, M—C equation and M—K equation were relatively higher. However, the maximum and minimum air temperature, wind speed, hours of sunshine tended to decline with the increasing forecast horizon; the accuracy of minimum air temperature forecast was higher than that of the maximum air temperature. The mean accuracy of P—T model was the highest (95.06%) among all models, meanwhile, the HG—M equation, M—K model, PMT1 model were in turn. The prediction accuracy of selected four models were higher than other models, but the P—T and HG—M models could satisfy the requirement of higher accuracy and simplify the calculating procedure. So for ET0 middle and short term forecast, the P—T and HG—M models could make a great contribution to improve the accuracy of irrigation forecast.

Abstract:To provide a method for measuring soil moisture content in mass based on frequency domain reflectometry, a tube-pin type soil mass moisture content probe, consisting of a tube and a pin, was designed. Lou soil was used as sample to test the probe’s performance in measuring bulk density. At 50, 100, 150, 300 and 500MHz of the signal frequency, the influence of mass moisture content from 2.58% to 21.43%, bulk density from 0.80g/cm3 to 1.30g/cm3 and temperature from 10℃ to 50℃ on voltage ratio at probe to source signal were studied. Mathematical models describing the voltage ratio as functions of moisture content, temperature and bulk density were established. The feasibility of the models in predicting moisture content from voltage ratio, moisture content and temperature were analyzed. The results indicated that the absolute error of probe in measuring soil’s bulk density was within -0.129~0.016g/cm3. Soil moisture content, temperature, bulk density and signals’ frequency had obvious effects on voltage ratio. At 50, 100 and 150MHz, moisture content had obvious influence on voltage ratio. The model at 150MHz was better than the others at 0.01 significance level with the coefficient of determination of 0.8496. The absolute error between calculated voltage ratio and actual voltage ratio was within -0.166~0.159. The absolute error between calculated soil moisture content and actual moisture content was within -3.440%~4.039%.

Abstract:A typical irrigation area was selected as objective study area which has more than forty years history with wastewater irrigation in northeast China. Acquiring relevant data and model parameters, the soil—air exchange of organochlorine pesticides and its fractionation effect were deeply disscussed with application of fugacity approach. The results show that, in the certain cases of soil organic matters, the difference of soil—air partition coefficient (KSA) between HCHs and DDTs has one order of magnitude at daily average maximum temperature higher than at daily average minimum temperature; HCHs released into environment for secondary distribution more easily than DDTs. The rate of change of KSA value is different when every 1% enhanced in soil organic matter and gradually stabilizing with enhanced soil organic matter content. There is a negative correlationship between octanol-air partition coefficient (KOA) and fugacity fraction (ff ) of soil—air exchange, the correlation coefficients are: R=-0.743 (P<0.05),R=-0.763 (P<0.05), R=-0.776 (P<0.05) when soil organic matters are 1%, 2% and 3%, respectively. Application of ratio between soil and air concentration (Cs/a), in the constant cases of other parameters, the soil and air concentration will affect the soil—air exchange of HCHs and DDTs. The primary and secondary fractionation effect of HCHs and DDTs further suggested that the soil properties and physical—chemical properties will affect their fractionation effect.

Abstract:At present, many studies are carried out on influencing factors of soil moisture evaporation (SME), mechanism and controlling technology of SME at non-freezing period. However, the researches about SME during freeze-thaw period are few because the monitoring on SME is difficult. In order to reveal the influence of groundwater level depth and soil texture on SME during seasonal freeze-thaw period, based on two successive freeze-thaw period monitoring of soil water content and temperature of the lysimeter, SME of sandy loam and loamy sand under four kinds of groundwater level depths (0.5m, 1.0m, 1.5m, 2.0m) was simulated by using SHAW model. The results show that the soil is thawing in day and freezing at night, and then liquid water is more during unsteady freezing stage and thawing stage. SME of sandy loam and loamy sand are more than 91.7% and 81.8% respectively during freezing and thawing periods. SME was increasing with the increase of groundwater level depth while it was lower than 0.31mm during steady freezing stage. SME was 47.28mm for sandy loam and 25.60mm for loamy sand when the groundwater level depth was 0.5m. SME decreases exponentially with the increasing groundwater level depth during freeze-thaw period, and the decreasing amplitude of SME for loamy sand is more obvious for its larger soil particle diameter.

Abstract:The recent progress of multifunctional catalysts, such as microbes, bacterium, enzymes, microelements, adsorbents, foaming agents, chelating agents, dyes, inhibitors and so on, used in the anaerobic fermentation was reviewed. This paper also emphasized the roles of the biocatalysts in the process of anaerobic fermentation, discussed the several critical issues in the fermenting methane bacterium, process control, waste disposal using a systematic processing and highlighted the advantages of the use of catalysts for fermenting methane. Also, the perspective of the biocatalysts in anaerobic fermentation was given. The biogas production can not only make biomass resources deeply developed and recycled, but also cause the waste harmlessly treated and effectively utilized, transforming the trash into treasure and making the harm to benefit, which are of great practical significance to solve the present energy crisis and environmental pollution problems.

Abstract:The anaerobic digestion fiber for producing ethanol was conducted. The effects of different temperatures and total solid concentrations of anaerobic fermentation conditions on producing ethanol characteristic of anaerobic digestion fiber were investigated. The results showed that for the anaerobic digestion fiber obtained at medium temperature and low concentration fermentation (37℃, 6%), the loss of cellulose in pretreatment process was lower, and glucose conversion was higher in enzymatic hydrolysis, 33.17%. The ethanol production could reach to 41g/kg. In order to improve the ethanol yield, the conditions of pretreatment were optimized and methods of acid and alkaline pretreatment were compared. The results showed that alkaline pretreatment was more favorable. Under the mild temperature (60℃) condition, the weight loss rate decreased to 22%~56% and the recovery rate of cellulose was more than 80% after 1%~3% of NaOH pretreatment for 6~24h. Moreover, the glucose conversion increased during enzymatic hydrolysis, and ethanol yield was significantly improved. By optimizing the pretreatment parameters, the conditions of 3% NaOH, 60℃ and 6h obtained maximum ethanol yield, 87g/kg.It effectively improved the efficiency of digested fiber for ethanol production.

Abstract:Evaporation was applied to concentrate biogas slurry. The effects of low temperature evaporation, atmospheric evaporation and vacuum evaporation on biogas slurry concentration were investigated. Results showed that the low temperature evaporation (room temperature, 25℃, 35℃, 45℃, 55℃, 65℃, 75℃, 85℃) had a great impact on the ammonia nitrogen concentration of biogas slurry, and almost all ammonia (98%) were lost, which has disadvantages on the recovery of nutrients. It showed that when the initial pH value was less than 4 in atmospheric evaporation, the water quality of the effluent (ammonia is lower than 41.0mg/L) could meet the demand of Discharge Standard of Pollutants for Livestock and Poultry Breeding (GB18596—2001). Experimental results of the vacuum evaporation showed that vacuum degree（-0.03～-0.08MPa） had little influence on evaporation results. Vacuum evaporation of biogas slurry with different initial pH value showed that compared with the atmospheric evaporation, vacuum evaporation could reduce the content of ammonia nitrogen and chemical oxygen demand (COD) in effluent and improve quality of effluent. When the initial pH value of biogas slurry in vacuum evaporation process was less than 5, the effluent (ammonia is lower than 61.8mg/L) could meet the discharge standard. Therefore, the most effective operation for the whole system is vacuum evaporation.

Abstract:To discuss the quality of fermentation caragana powder for substrate production, the randomized block design was adopted. Taking caragana powder as main raw material, dried chicken manure, cake and urea as nitrogen sources, and cellulose degrading bacteria as exogenous microorganisms, the effects of type and proportion of nitrogen on fermentation performance parameters of caragana powder for substrate production were studied. The results showed that the type and proportion of nitrogen sources had a significant impact on caragana powder matrix fermentation composting decomposed velocity and products. With 75% organic fertilizer+25% chemical fertilizer and 50% organic fertilizer +50% chemical fertilizer treatment of caragana powder pile faster, duration of high temperature was long (>50℃, reached to 10d and 9d, respectively,>55℃, reached to 6d), accumulated temperature was high, and maturity of powder caragana time was short. The total organic carbon were 355.54g/kg and 359.86g/kg, total nitrogen were 22.36g/kg and 0.385g/kg, nitrate nitrogen were 22.21g/kg and 0.337g/kg, ammonium nitrogen were 0.049g/kg and 0.051g/kg, carbon and nitrogen rate was 14.69% and 14.35% respectively. The cellulose and hemicelluloses degradation rate were over 44%, lignin degradation rate was over 37%, humic acid content were 37.12% and 37.08% respectively. The decomposition of organic matter caragana powder and cellulose degradation was accelerated. The composting of total nitrogen and nitrate content was improved. The nitrogen loss was effectively controlled. The fertility of caragana powder after maturity was ensured. The physical and chemical properties of substrate after maturity meet the requirements of an ideal substrate and the substrate extract will not produce toxic effects on seed. But considering the root growth, plant protection, fixed exchange with the outside air, water holding capacity and retention capacity of substrate, nitrogen sources of 75% organic fertilizer +25% fertilizer and 50% organic fertilizer +50% fertilizer caragana powder maturity substrate are considered to be more suitable for cultivation of vegetable crops.

Abstract:The mixing scheme of biomass constituents, including cellulose, hemicellulose and lignin, was designed by using simplex-lattice mixture design (SLMD) method. The pyrolysis characteristics of biomass constituents were observed by using a thermo-gravimetric analyzer and the kinetic parameters were calculated. In addition, a prediction model for kinetic parameters was established and the model was verified by test. The results showed that the reaction order n, activation energy E and frequency factor A of cellulose were 1.20, 134.50kJ/mol and 3.49×1012s-1, respectively. Pyrolysis of cellulose was much rapider and more violent than the other two components. The value of n, E.and A for hemicellulose were 1.30, 33.51kJ/mol and 9.43×103s-1 and that for lignin were 1.32, 19.98kJ/mol and 107s-1. Pyrolysis of hemicellulose and lignin were relatively slow. Furthermore, three components in the mixed pyrolysis had interaction effect. Effects on the activation energy and the frequency factor of cellulose were significant while effect on the reaction order of hemicellulose and lignin was remarkable. The kinetic model is precision and it can effectively predict the biomass pyrolysis kinetic parameters.

Abstract:Hydrothermal treatment (HTT) of biomass is a technique which using hot, pressurized water to convert biomass for yielding a solid, coallike product. Therefore, the treatment and utilization of HTT liquid products has a key effect on its commercial application. This current research work mainly focuses on the effects of products on characteristic from HTT which using recycled process water for multiple process cycles. The hydrothermal experiments were carried out in an autoclave using wheat-straw as raw materials at temperature 220℃ for residence time 120min with a 30∶1 water and biomass mass ratio. The micro-structure, chemical composition and thermal stability of solid products were characterized by using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Thermogravimetric analyzer (TGA) with differential scanning calorimetry (DSC). The results show that with successive recycling, the mass yield and sequestering carbon rate in the solid gradually increased. Compared with the initial HTT, mass yield and sequestering carbon rate after six recycles rose to 78.7% and 92.4%. Upon increasing recycling, the level of structural order in the solid increased, which suggested that the solid tended to further aromatize/graphitize. At the same time, the functional group and aliphatic structure decreased. The TGA analysis results indicated that the thermal stability of solid also increased as the number of cycles increased. Water recirculation during hydrothermal treatment of wheat straw could increase the HTT solid yields and improve their physical and chemical characteristics. 

Abstract:Cattle manure is a kind of complicated biomass mainly consisting of hemicellulose, cellulose, and lignin. In order to study the pyrolysis characteristics and interaction among these constituents, Van Soest method was adopted to effectively segregate hemicellulose, cellulose, lignin, extractives and ash. The obtained detergent fibers and cattle manure original samples were investigated by using scanning electron microscopy to analyze their microscopic structures. The results showed that the apparent morphology of cattle manure and detergent fibers was changed from surface compression without cracks and holes to a honeycomb structure with numerous cracks and holes along with the washing process. Furthermore, those samples were also addressed by dynamic thermogravimetry and derivate thermogravimetry (TG-DTG) method. Thermogravimetric experiments showed that the pyrolyis rate of acid detergent fiber mainly including cellulose had the largest value among the detergent fibers, e.g. 14.310%/min, and the strong acid detergent fiber at the smallest one with the value of 1.615%/min. The pyrolysis processes of the different components were intrinsically interacted with each other. Hemicellulose inhibited extremely the devolatilization of cellulose, resulting in the volatile rate of cellulose was decreased from 14.310%/min to 7.617%/min. For the presence of the neutral detergent dissolved matter, the starting temperature of pyrolysis of cattle manures was reduced, and the thermal degradation rates of hemicellulose and cellulose were also restrained.

Abstract:An cellulase hydrolysis process and an anaerobic fermentation process to produce hydrogen from four kinds of common straw biomass were investigated. The hydrolysis of four kinds of common straw biomass and capacity of their hydrogen production were experimented by using fractal-like kinetic. And the correlation between the ability of biological hydrogen production and the growth of photosynthetic bacteria was analyzed. As a result, the kinetic equations of straw biomass hydrolysis and hydrogen production were got. The experimental results show that the effect of straw biomass hydrolysis and the capacity of hydrogen production from large to small are wheat straw, corn straw, sorghum straw and cotton stalk. With the enzymatic degradation, the reduction sugar content are 19.88g/L, 15.72g/L,14.04g/L and 9.41g/L. The cumulative amounts of hydrogen production are 515.7mL, 362mL, 194.8mL and 123.95mL. In this period, the hydrogen production rate reaches maximum in exponential phase of photosynthetic bacteria. Meanwhile, the fractal-like kinetic brings out the direct proportion among the straw biomass hydrolysis kinetic parameter, the reduction sugar content and the cumulative amount of hydrogen production. It lays a reference for further improving the process theory and technology of hydrogen production with straw biomass.

Abstract:This study mainly investigated the effect of acid and alkaline pretreatment on Platanus orientalis (known as the French phoenix) leaves, and also the simultaneous saccharification and photo-hydrogen production from the leaves were pretreated with acid and alkali of different concentrations. Taking cumulative hydrogen production and hydrogen production rate as assessment indicators, the photo-hydrogen production capabilities from leaves with different pretreatments were compared and the modified Gompertz equation was used to analyze hydrogen production process. The results showed that H2SO4 pretreatment could effectively improve the performance of photo-hydrogen production comparing with Ca(OH)2 pretreatment, and the 4% H2SO4 pretreatment was the best pretreatment. The maximum hydrogen concentration, the cumulative hydrogen production and the highest specific hydrogen production yield rate were 66.34%, 369mL, 11.03mL/h, respectively. The exploratory research was carried out about the dilute acid treatment liquid for recycling and reducing the cost of preprocessing.

Abstract:Charcoals were derived from cotton stalk pyrolysis in a fixed-bed reactor at different temperatures (400℃, 600℃, 800℃, the samples are labeled as CS—400, CS—600, CS—800, respectively). The charcoals were characterized by elemental analysis, nitrogen adsorptiondesorption isotherms, Boehm titration and Fourier-transform infrared spectroscopy. The results show that cotton stalk charcoal obtained at 400℃ has a large number of organic groups on its surface and poor pore structure. With the increase of pyrolysis temperature, oxygenic organics in cotton stalk decompose further, which leads to the reduction of acidic functional groups on charcoals surface, and the increase of the pyrone structures of the basic groups, meanwhile, pore structure is improved significantly and the surface area is increased, especially for the micropores. The H/C mole ratio, surface acid and basic functional groups of cotton stalk charcoals are the main factors that influence the removal efficiency of furfural. The increase of pyrolysis temperature promotes removal of furfural onto cotton stalk charcoal. With the increase of carbonization degree, the basic functional groups increase, while the acidic functional groups decrease, which results in the increase of π—π dispersion between the surfaces of cotton stalk charcoals and furfural molecular, therefore the best removal efficiency of furfural is obtained by cotton stalk charcoal pyrolyzed at 800℃.

Abstract:For photo-hydrogen production offers the possibility of being renewable and carbon neutral, it has promising prospects in the clean energy future. The microorganisms from several natural sludge pools where has plenty of sunlight and with high organic load were used as samples. The mixed culture of photosynthetic bacteria (PSB) was cultivated by using selective medium method. Bacteria partial reflux device was employed for screening and optimization of mixed culture. The hydrogen production characteristics of mixed culture of PSB using cattle manure wastewater were also investigated. The results showed that, the mixed PSB culture grew fast and stable, and the conditions for its growth and hydrogen production were less strict than that of pure PSB. The optimum conditions for bacterial reflux were cell reflux time of 36h and cell reflux volume of 30%. The maximum hydrogen production rate was 28.3mL/(L·h), and mean concentration of H2 was 55%. When using cattle manure wastewater as substrate for biohydrogen production by mixed PSB, the hydrogen production duration was up to 216h, the average hydrogen production rate was 11.65mL/(L·h), substrate utilization ratio was 71.48%, and the average substrate conversion rate was 52.60mL/g. 

Abstract:To increase the energy-efficient performance, a forming machine with geared-roller annular mould was proposed. Based on the analysis of mechanism kinematics, the motions of geared roller and annular mould were non-interference with each other. Compared with normal annular mould, a larger grab angle in the structure was good for enhancing the production efficiency. Particles of locust, of which moisture content were 8%～20%, were taken as raw materials. The experimental results showed that the specific energy consumption was 56.82kW·h/t and the formation density was 1.085g/cm3. Correspondingly, the output was improved by 3.36%～6.25%, the energy consumption was decreased by 5.77% and the density was increased by 3.33%. Meanwhile, the energy consumption was 50.3kW·h/t with the moisture content of 16% and speed of 200r/min.

Abstract:China is the biggest concentrated apple juice producer in the world with a production of millions of tons of apple pomace every year. It is an important comprehensive utilizing approach by separating of polyphenols from apple pomace. A nano-material for adsorption of polyphenols from apple pomace was prepared. The moulding condition and preparation process of methylacrylic acid nano-materials was optimized by changing the dosage of methylacrylic acid(MAA), ethylene glycol dimethacrylate(EDMA), azodiisobutyronitrile(AIBN) and acetonitrile, using chemical precipitation method and field emission scanning electron microscopy, and conducting the experiments of adsorbing of polyphenols from apple pomace by the prepared nano-material, so as to provide reference for the comprehensive utilization of apple residue. The results showed that the best preparation condition of this material was methylacrylic acid of 2.5mmol, ethylene glycol dimethacrylate of 2.5mmol, azodiisobutyronitrile of 1.00mmol and acetonitrile of 20mL, under which the adsorption capacity of obtained nano-material to polyphenols could achieve to 33.42mg/g, and the desorption rate was 61.13% at the same time. 

Abstract:Random forest (RF) regression algorithm was utilized for determination of protein content in fishmeal samples based on near-infrared (NIR) spectrometry. Considering the randomness of RF method, the optimized models were selected by tuning the two vital modeling parameters of the number of decision trees (ntree) and the number of split variables (nsv). The descending of Gini coefficient (G) is taken as the indicator performing the modeling importance of NIR valuables. It was used to select the informative wavelengths for NIR analysis of fishmeal, with an aim to improve the accuracy of quantitative models. According to statistical theory, we tried to select equivalent optimal model with relatively low computational complexity. The optimized RF model needed to construct 471 decision trees and randomly select 103 wavelength variables for node splitting when the decision trees grow. Simultaneously, 52 NIR informative wavelengths can be selected out according to the average of G descending values based on the trees in the forest. The equivalent optimized RF model output the root mean square error (RMSEv) and correlation coefficient (Rv) of validation set were 3.970% and 0.943, respectively. The optimized model was further evaluated by using the prediction samples that were excluded from modeling process, with the RMSEp of 5.271%, and the Rp of 0.906. Results showed that RF regression combined with G coefficients for wavelength selection is feasible and effective to improve the NIR predictive ability for quantitative determination of fishmeal protein.

Abstract:A semi-supervised classification algorithm named DE-self-training for hyperspectral remote sensing images was proposed. Firstly, taking a few labeled samples as initial training set, the initial classification model was constructed by using improved Self-training algorithm to classify unlabeled samples. Then, partial samples and corresponding labels were selected randomly as a proportion from classification results into training set, and the augmented training set was used to retrain the model to classify the unlabeled samples. Then, the algorithm continued the process of training-classifying-picking out samples to augment training set iteratively. During this process, in order to ensure the training set’s quality and the correct labeling of new increased samples, the algorithm edited and purified mislabeled samples by using data editing strategy based on the nearest neighbor rule. Finally, the proposed algorithm trained classification model iteratively to get a more accurate result until the unlabeled samples set was empty. In the experiments, AVIRIS Indian Pines and Hyperion EO—1 Botswana data were used to test the algorithm. According to the comparison with SVM classification results, the DE-self-training algorithm can get higher accuracy and Kappa coefficients by utilizing unlabeled samples information under limited labeled samples.

Abstract:The multi-kernel support vector regression (MK—SVR) was used to construct remote sensing monitoring algorithmic models for estimating leaf area index (LAI) in wheat. The experiment was carried out during 2010—2013 in Jiangsu Province, China. Based on LAI in wheat and synchronous China’s domestic HJ—CCD multi-spectral data at jointing stage, booting stage and anthesis stage respectively, the relationships between LAI and eight vegetation indices were analyzed at corresponding period. Taking these vegetation indices which were significantly related to LNC at 0.01 level as input parameters, the remotely estimating model was established based on MK—SVR to invert LAI, named the MK—SVR—LAI model. Meanwhile, in order to evaluate the MK—SVR—LAI model, single kernel support vector regression (SK—SVR）and partial least squares (PLS) were employed to establish models at each period, named the SK—SVR—LAI and PLS—LAI models. Comparing predicted LAI by model with actual measured LAI, the coefficient of determination (R2) and root mean square error (RMSE) were used to evaluate models. The results showed that the lowest RMSE and the highest R2,were obtained by using MK—SVR—LAI model at each stage, of which the RMSE and the R2 were 0.2931 and 0.7624 at jointing stage, 0.4668 and 0.8018 at booting stage, 0.5486 and 0.6689 at anthesis stage, respectively.

Abstract:Drought and flood disasters are the main meteorological disasters in China. For the vegetation index and land surface temperature retrieved by optical remote sensing data for drought and flood disaster monitoring has a lag in time, precipitation data can reflect the surface dry and wet state more timely and intuitively. Current methods for monitoring drought and flood disasters based on precipitation extremerely primarily on point-based in situ meteorological stations. Tropical rainfall measurement mission (TRMM) microwave remote sensing offers the possibility of quantifying drought and flood conditions over large spatial extents. This research used scale of 12 standardize precipitation index (SPI12) to explore the spatial and temporal characteristics of flood and drought in Jiangsu Province based on the TRMM 3B43 monthly precipitation data from 1998 to 2014. The month-to-month changes and spatial distributions of SPI12 were got from 1999 to 2014 in Jiangsu Province. It concludes that: the probability of drought and flood disasters happened in Jiangsu Province is 34.08% during 16 years, and the drought (16.74%) is closed to the flood (17.34%). Jiangsu Province is easily influenced by drought and flood disasters in every season of the year, and drought and flood disasters happened alternately. Extreme drought or flood disasters in Jiangsu Province happened many times from 1999 to 2014. Also, central of Jiangsu Province is easily affected by drought and flood disasters. At the same time, this research shows that the TRMM data can be used to monitor the flood and drought disasters in large spatial extents effectively.

Abstract:Regional locust does great harm to agricultural production. Real-time monitoring of the development of locust is of great significance for the locust control. We took three counties in northern Chifeng City of Inner Mongolia as the study area. Firstly, we classified locust host plants by using the sophisticated remote sensing classification algorithm on the Landsat8 OLI data, overlapped with prior locust distribution regions, and distinguished the locust suitable bases regions. Then, we retrieved some important locust habitat parameters, such as leaf area index, land surface temperature and soil moisture by using Landsat8 satellite data. Meanwhile, the synchronous investigation data, land cover data, historical locust hazard data were combined for analysis and modeling. Finally, we used stepwise regression analysis to obtain the relationship between locust density and leaf area index, land surface temperature and soil moisture. The model results showed a high accuracy with R2 of 0.50 and RMSE of 3.17. It is indicated that the Landsat8 satellite data has a certain potential in locust remote sensing monitoring, and the research provides an important reference for similar studies.

Abstract:The internet of things has become one of the most important data sources of agricultural big data, therefore automatic quality control of observational data is very important to agricultural production analysis and basic scientific data application. To solve the data missing, outliers excluding, perceived sensing failure and long-term prediction problems of the nonstationary time series data observed in agricultural systems, smooth Gaussian prior of weak assumptions on typical agricultural data was utilized; the dynamic system was built which was characterized by state space equations based on Gaussian process model; through the train set learning, the sensed variation models considered noise distribution were formed, and prediction error bar was provided with uncertainty measurement for the prediction data. For the problems of missing data and outliers excluding of raw data, short-term forecasts based on Gaussian process were adopted to fill with missing data, and its uncertainty measurement was used to detect outliers. Therefore, the outliers were removed and replaced with prediction value, and further sensing failure could be determined on the basis of accumulated outliers in certain time slice. The multi-step iterative method based on the uncertainty spread of input data was given for long-term prediction to track the dynamic trajectory of agricultural sensing data, and an uncertainty measurement could be provided for its predictive value. The data analysis of real sensed collection greenhouse microclimate verifies the feasibility of quality control of agricultural time series data based on Gaussian process in server-side.

Abstract:A framework for community vegetable shop to manage the transaction information and trace products was created. In this system, information acquisition was carried out based on barcode traceability electronic scale. The management core of the system was the database of transaction information. A mobile was used as the barcode scanner for tracing. The barcode traceability electronic scale integrated related models to achieve many functions, such as weighting, authentication, label printing and data uploading. To build the transaction management and traceability system of community vegetable shops, the electronic scale’s data transaction and analysis were carried out, and the mobile’s recognition technology of 2-D code which contained multiple pieces of information was improved. By building the simulation environment, the data transmission stability of multiple electronic scales, which were connected with the computer at the same time and the traceability function by scanning 2-D code with a mobile, was tested. The results show that the transmission success rates are above 99% by either real-time transmission or centralized transmission. With the increase of products number in one label, there is a decline in both recognition speed and recognition success rate of different pixel mobile phones. Meanwhile, the mobile phone with 8 million pixels has obvious advantages in recognition speed.

Abstract:Sows are lateral lying when they are willing to lactate, while they will turn into sternal lying or tilt lying as refusing to lactate. So the lateral lying time can be used as an important parameter to evaluate the maternal behavior of sows. Firstly, a set of monitoring nodes with sensor MPU6050 and bluetooth module was designed to monitor the behavior data at their lactation periods (28d). Then, the attitude angle in feeding time was counted, and the deflection angles of nodes were computed to achieve collision correction. Thirdly, combined with numerical features of each posture, the baseline of acceleration curve was extracted by using Haar wavelet method. Finally, the postures were divided into stand, side and tilt with the algorithm of SVM, and 10 ‘Xiaomeishan’ sows were chosen. The results showed that the deflection was reduced by the correction algorithm of node, meanwhile, the data sets were normalized and the interference of energy movement was removed by wavelet transform algorithm. The test results of 392 samples indicated that the recognition rates of lateral lying on the left and on the right were 65.8% and 90.1%, respectively, while the accuracy of lateral posture and sternal lying were 75.4% and 83.3%, respectively. Above all, the analysis of posture can effectively reflect the lactating willing of sows.

Abstract:To characterize plant wilting status, a laser scanner based on triangulation principle was used to obtain 3-D images of zucchini. Four wilting indices (TB_3D, RLWI-2DFT, RTPLA, RS) were developed by using different mathematic methods (differential geometry, 2D Fourier transform, top projected area, standard deviation) to identify the plant wilting. It was observed that the indices were capable of sensing the stress response of zucchini from slight wilting to severe stress levels. Regression results showed that TB_3D had a linear relationship with ambient temperature and global radiation, the decision coefficient were [0.710, 0.721] and [0.513, 0.589], respectively. Besides, TB_3D was also found to be linearly correlated with stem diameter, and R2 was 0.845. Additionally, the correlations of wilting series characterizing by these four wilting indices were analyzed respectively. The R2 of each two indices was larger than 0.736. The results showed that the four wilting indices had the similar effects.

Abstract:In order to improve efficiency of field operation in normal plot investigation, the photograph plot method was studied. The binocular stereo camera was chosen as the main tool. We placed the binocular stereo camera vertically in the center of plot, took twelve 30-degree-shots and got twelve groups of stereo images in turn. The field visual examination was used to check the shielding tree. After the supplementary surveying of the shielding tree, we used forward intersection to obtain the coordinate of homonymy points in the stereo images so as to extract the diameter and relative coordinate of the target tree. The photograph plot was then finished after all the coordinates had been transformed to the same coordinate system by the rotation angle. In order to verify the proposed method, nine fixed sample plots were chosen as examples to make a comparison between the results of photograph plot and the normal method. The results included the diameter and the coordinate of each target tree, the volume of fixed sample plot and the working time of two methods above. The results show that the average fractional error of plot volume is 5.5%, and the maximum error is 8.2%. The comparison results confirmed the feasibility of photograph plot.

Abstract:The sensor of chlorophyll a based on fluorimetry was designed. It can satisfy the long-term and real-time requirement of sea and lake detection. Firstly, this paper introduces the basic principle of fluorimetry’s detecting chlorophyll a based on the former research. The fluorimetry sensor belongs to optical sensor. Optical path design, the key part of hardware, was described as follows: first of all, the optical sensor probe was designed; then the 460nm super bright blue light diode was selected as the fluorescence excitation signal source, because chlorophyll a has the strongest absorption in 430~470nm blue brand. Four sets of super bright blue light emitting LED were used, which suited the characteristic of chlorophyll a’s absorption and had the advantages of low power consumption, small volume, low cost and simple circuit design. For the photosensitive receiver module, there are advantages and disadvantages of different electric converters. Finally, the light-sensitive diode was chosen, as it satisfied the requirement of weak fluorescent signal of chlorophyll a. The sensor was calibrated at last. This paper built the standard curve of sensor and the standard curve based on the direct fluorescent method, the correlation coefficient of sensor meansurement is 0.998, standard deviation is 0.05μg, and limit of detection is 0.25μg/L. 

Abstract:The theoretical research on soft-terrain machine systems has scientific significance and engineering application value to agriculture, forestry, mining and military. Firstly, the development on research of the basic theories and the latest research on soil—wheel interaction relationship of soft-terrain machine systems were reviewed. Then, the anti-adhesion and resistance reduction mechanism of soil animal from morphology, structure and flexibility, as well as the bionic theoretical basis for terrain-machine soil-engaging component were also reviewed. Secondly, the measurement methods for terrain mechanical properties and the soil bin testing equipments for the research were introduced. Moreover, the development on research of numerical simulation methods for the terrain machine systems was analyzed and summarized. Finally, the applications of the terrain machine systems theories and methods for soil-engaging component and vehicle motion mechanism in the future were discussed.

Abstract:In order to investigate the effect of high-pressure conditions on the control-valve of common rail injector, a sealing reliability test was carried out in a conventional type of common rail injector, and an unsteady vapor-liquid two-phase flow CFD simulation about the control-valve was performed with AVL—Fire. The displacement measurement of armatur-pin of solenoid-actuator was accomplished for the boundary condition setting of computational dynamic grid. The simulation was validated against the experimental result of fuel backflow measurement in terms of mass flow rate. The reliability test result shows that cavitation damage appears on the conical seat surface of control-valve. The simulation result demonstrates that obvious cavitation phenomenon occurs in the guide-hole of the control-valve when inlet pressure boundary condition is increased to 250MPa level. It also indicates that at three typical inlet pressure levels, viz., 150MPa, 200MPa and 250MPa, the ratio of mass exchange rate of vapor-liquid phases is 1∶1.187∶1.437. With respect to time dimension, the mass exchange rate reaches a peak at the incipient stage of closing course of the control-valve.

Abstract:Taking the flow characteristics of special shaped valve port in proportional valve as the research objects, the structural mathematic models of U-shaped, V-shaped and round & divergent shape valve port were established, and also the referencing simulation and experiments were carried out. The flow characteristics were analyzed under the conditions of different pressure drops and different openmouthed sizes of special shaped valve port. The results show that the round & divergent valve port has satisfied control linearity on flow. At the same time, the similar experiment method was adopted, the proportional valve model was designed by using Reynolds similarity criterion with water selected as medium. The flow field visualization experimental study with 2D—PIV testing technology was adopted to analyze the features of special shaped valve port flow field. The results show that the round & divergent valve port possesses good flow characteristics and reduces the area and intensity of vortex which promisingly causes minor flow loss. This study provides design reference for the structure improvement of valve port in proportional valve.

Abstract:In order to establish the mathematical models of geometric errors of machine tools rapidly and precisely, one parametric modeling approach based on Chebyshev polynomials was proposed. Firstly, according to the measured data of basic geometric errors of machine tools, the displacement of the axis was converted to Chebyshev variable. Secondly, the values of Chebyshev polynomials with different orders were calculated with Chebyshev variable. Then, coefficients of Chebyshev basic functions were calculated by using multiple linear regression methods according to Chebyshev variable and Chebyshev values, and the model about Chebyshev basic functions was obtained. At last, the mathematical models of basic geometric errors were established by inputting the conversation of the displacement of the axis and Chebyshev variable. The modeling was simple and programming; and the high approximating accuracy of Chebyshev polynomials made models precise. The comprehensive mathematical models were established by inputting parametric models of geometric errors into geometric models of machine tools. Then, the geometric error fields of working zone for machine tools were obtained. Taking the MV—5A three-axis machine tool for an example, the parametric models of all geometric errors were inputted to geometric error model of this machine tool to obtain the comprehensive mathematical model of geometric errors. Then, geometric error fields of working zone of this machine tool were computed, which laid the foundation for machine design and the error compensation.

Abstract:The magnetization model of a magnetostrictive force sensor was studied based on Fe-Ga alloy. The magnetic path of the sensor was optimized with 3D finite element method. Simulation results showed that the field distribution became linear when the magnetic path was optimized. In order to analyze the influence of biased field and loaded stress on material magnetization, the magnetization model was developed based on the homogeneous energy equation. The magnetic field and stress were taken as the independent variables in the Gibbs free energy formula thus the model could respond to both field and stress. The model was numerically solved using Newtons iteration method. In order to verify the model, a testing system was developed and both Fe-Ga alloy and Terfenol-D were tested. Comparisons of simulations and experiments showed that the proposed model could predict the changing of the magnetization properly. The influence of the biased field could be predicted as well. Comparisons of Fe-Ga alloy and Terfenol-D showed that Fe-Ga was more sensitive to the biased field and the hysteresis nonlinearity was lower than Terfenol-D. Since there is no annealed stress in Terfenol-D, it is observed negative magnetization when the material is subjected to cyclic stress with low biased field.

Abstract:PEMFC is a complex system which is often affected by many parameters. Its time-varying performance, nonlinear performance and uncertainty lead to its dynamic output unable to be controlled. Taking that into account, the controller based on adaptive prediction control was designed to control the dynamic output of PEMFC. The neural network model of PEMFC system was used as a predictive model of the controller, which could make full use of the nonlinear fitting ability of neural networks. Through optimizing the neural network connection weights and threshold in real time, receding horizon optimization could be realized, which could guarantee the real-time control and the effective electrochemical reaction. During the control process, the control precision and response speed of the system could be improved by the introduction of the negative feedback control to the front of adaptive model and predictive control. The simulation results show that the adaptive prediction controller owns adaptive ability, stronger robustness, stronger learning ability and higher control precision, and it has perfect control effect on the dynamic stability of proton exchange membrane fuel cell output characteristics. 

Abstract:In order to improve the positioning accuracy of micro transmission platform, the geometric errors were mainly analyzed. The mapping relationship between output pose errors of micro transmission platform and geometric errors of structural parameters was built through the method of differential relationship. And then the influence of structural parameters on the micro transmission platform positioning accuracy was analyzed by introducing the error weight coefficient, and the precision compensation model of micro transmission platform was established. Then a simulation calculation through Matlab software and an experiment test on the experimental platform were carried out. The results of simulation and experimental test showed that the error analysis model based on the weight coefficient method is reasonable, and what’s more, through the established precision compensation model, the micro transmission platform’s positioning error descended to 10%~15% after compensating, which was 20%~30% before compensating, and that made the micro transmission platform achieve a higher positioning accuracy.

Abstract:According to the demand of multi-dimensional motion simulation, a class of planar underactuated simulator with cylindrical helical springs was put forward. The workspace of the proposed simulator was restricted by the axial and lateral stiffness of cylindrical helical spring, and 3-DOF of the proposed simulator was driven by only two drive limbs and dynamic coupling effects. The cylindrical helical springs could be seen as an elastic limb Re/Pe/Re, so the simulator can be transformed to an elastic underactuated mechanism, 2RPR/2Re/Pe/Re. The input selection of equivalent mechanism was analyzed by using Grassmann geometry. Based on screws, the kinematics of equivalent mechanism was given. The kinematics can be represented to any frame easily by using the shifting property of the screws. Referring to the influence coefficient and virtual work principles, the statics analysis was performed, and the statics constraint equation was gotten. Finally, the continuous nonlinear compliance model of the mechanism was established, and based on this, the direction stiffness was given.

Abstract:Because of complex size parameters and dynamic performance in high-speed 6—PSS parallel robot, a multi-objective optimization method based on work space was proposed. The aim of this method was to improve the dynamic performance. At first, the kinematic equations of parallel robot were calculated, the dynamics equation was solved by using the Lagrange equations, and the optimize range of size parameters was obtained according to the constraints analysis and work space analysis of parallel robot. Then, the influence trend of various parameters on the critical dynamic performance was analyzed. The optimization objective function was proposed by using comprehensive analysis of the results. At last, the size parameter optimal solution of parallel robot was obtained by using optimized mathematical model. Through the simulation, the dynamic performance values before and after optimization, including the driving force, speed, power, etc. were compared which could prove the correctness of the proposed optimization method. The obtained results showed that the optimization algorithm was correct and effective, which can provide an effective method for optimizing parameters design in high-speed parallel mechanism.