Abstract:Control strategy of DPF regeneration based on inner diesel engine-based machine is developed, which enhances the exhaust temperature by using of inner machine measures to change the combustion of diesel engines. This method can achieve safe and effective DPF regeneration without making any changes and adding auxiliary systems in the diesel engine. Firstly, technical program and monitoring system of DPF regeneration based on inner diesel engine-based machine is proposed and designed. Secondly, soot loading model based on differential pressure, engine speed and load is established to improve the accuracy and consistency of DPF regeneration. Finally, the measures model of exhaust temperature containing the diesel engine speed and load factors, as well as the regeneration temperature model, is designed to ensure process of DPF regeneration is effective and safe. The experimental result shows that the process of DPF regeneration is effective and safe by using of this regeneration method.

Abstract:SCR post-processing technology had more advantages than other technology which applied to Euro Ⅳ/Ⅴ diesel engine. In order to develop control strategy of SCR post-processing system, methods of experiment and simulation were employed. Firstly coordination control strategy was designed and tested in matlab based on the state machine theory, then raw emission model, NH3 target coverage rate estimation model and mass ratio calculation model of NH3 and NOx chemical reaction from SCR catalyst were calibrated by bench test, finally correction algorithm for heat hysteresis of catalyst substrate and NH3 leak control strategy in the transient operation condition were fulfilled, which improved the SCR control system robustness. The dosing control unit using above control strategy was adopted in the target engine, which made NOx conversion efficiency achieve 60 percent and average NH3 leak equal to 1×10 -5 . Emission NOx value of ESC and ETC was 3.01g/(kW·h)和3.15g/(kW·h), which validated the heavy duty diesel engine can satisfy Euro Ⅳ emissions regulations.

Abstract:The experimental study on the effects of structural parameters of combustion chamber and injector, as well as EGR on combustion process, performance and emissions, was conducted on a common-rail heavy-duty(HD) diesel engine matched with two-stage turbocharger. The results of numerical simulation show that compared with CR17.5, CR16.8 and 16.2 can enhance in cylinder turbulent kinetic energy, promote the mixture of air and fuel and lead to more homogeneous mixtures. The tested results show that compared with CR17.5 and CR16.2, CR16.8 can reduce BSFC because it can enhance burning rate, shorten combustion duration. CR16.2 will lead to an increase in BSFC due to its much lower compression ratio. The results of numerical simulation and test demonstrate that NOx and soot emissions of CR17.5 are highest of all at a given EGR rate under high load conditions. However, the final soot level of CR17.5 is lower than that of CR16.2. Compared with other combustion chambers, CR16.8 can reduce soot and improve the trade-off of NOx soot due to its higher turbulent kinetic energy. The tested results concerning fuel injector matching show that relative to the fuel injector with straight holes, soot can be reduced and the trade off of NOx soot can be improved greatly via using S4 and S5, both of which have taper holes.

Abstract:The three-dimensional numerical simulation of gas-liquid two-phase flow in diesel nozzle with convergent conical orifice（CDN）was carried out by using the mixed multiphase cavitation flow model, and the effects of injection pressure, injection back pressure and needle valve movement on the cavitating distribution, the turbulent kinetic energy distribution, the mean flow velocity at outlet(MFVO) and the discharge coefficient were analysed. The results show that the increasing in the injection pressure or the needle valve`s open velocity will enhance the cavitation effect, strengthen the flow disturbance, improve MFVO and the cycle fuel injection quantity, which are beneficial to the performance of diesel engine, the fuel injection and atomization; with the increase of the injection back pressure, the discharge coefficient of CDN is increased slightly, but the cavitation effect, the flow disturbance and MFVO are decreased gradually; under the same injection condition or needle valve lift, the cavitation effect of CDN is weaker than that of diesel nozzle with cylindrical orifice, MFVO and the discharge coefficient of CDN are higher than those of diesel nozzle with cylindrical orifice.

Abstract:In order to investigate the evolution law of structure and chemical components of diesel engine particulates during passing through diesel oxidation catalyst (DOC) and diesel particulate filter (DPF), particulates samples emitted from an electronic control high pressure common rail, turbocharged, inter-cooler diesel engine with exhaust after-treatment device were collected on the glass fiber filters. Raman spectrums at different points were measured, and characterizations of the spectrums were compared. The results showed that the Raman spectrum of engine particulates was composed of five peaks and the Raman shift of the peaks changed within a very small range. Every characterization parameter describing the structure and components of particulates varied with the different measuring points, i. e. as the measuring point shifted backward, the ID1 /IG decreased, ID2 /IG increased, ID3 /IG ,ID4 /IG and IALL /IG had the trend of first increase and then decrease, which indicated that the changing process of structure and components of the particulates was not only a physical process but also a chemical one. On behalf of the degree of graphitization of the particulates of ID1 /IG increased with the backward shift of the measuring point, but the organic fractions in the particulates reached maximum.

Abstract:Tests were conducted by using TSI EEPS3090 particle size spectrometer to study the effect of fuel with different physical and chemical properties on particle size distribution in common rail diesel engine. For the fuels of different cetane number, the particle size was mostly between 5nm and 300nm and the particle size distributions were unimodal with peaks at 30nm with medium or small load. Increasing cetane number appropriately could make the ignition delay period shorter and the sustained combustion period longer, which would drop the number of nuclei mode particles. Meanwhile，the number of nucleation mode particles increased with more sulphur in the fuel. With the cetane number increased, the percentage of SOF decreased and the percentage of DS increased.

Abstract:A new thermal cycle called 2-phase working fluid thermal cycle for diesel engine was proposed, which consists of the dual cycle and Rankin cycle. The noble cycle was analyzed by thermodynamic method and the forums to calculate performance indexes were deduced. Take water as the phase-changing fluid for example, the influence rules between injection parameters and cycle performance were studied. The result demonstrates that the injection of water could alleviate heat load and enhance the power of engine, while the efficiency would be decreased compared with the traditional dual cycle. When the injection mass of water and fuel are equal at one cycle, the efficiency drops by 5.79% and the power rises by 6.36%.

Abstract:In order to study the influences of different turbulence models on the hydraulic performance prediction of the mixed-flow pump, the mixed-flow pump model with a specific speed of 465 was selected and numerical calculation was processed by employing the standard k-ε, RNG k-ε, k-ω, SST k-ω turbulence models respectively based on SIMPLEC algorithm and unstructured tetrahedral grids. The head coefficient, the efficiency and the shaft power were predicted by the simulation and then compared with the test data. In addition, the pressure and the relative velocity distributions were also analyzed. The results showed that the performance curves predicted based on the four selected turbulence models had basically consistent trends with the test data curves. Among the obtained results, the prediction results based on the standard k-ε and RNG k-ε model were more close to each other and the prediction results based on the k-ω and SST k-ω model were more close to each other. For the head coefficient and the efficiency, the prediction results based on the k-ω and SST k-ω model were more accurate under （0.6~ 0.9）Qd and the prediction results based on the standard k-ε and RNG k-ε model were more accurate under （0.9~1.3）Qd . For the mixed-flow pump model designed, it could be ensured that the performance prediction accuracy was within ±5%, which could meet the requirements of engineering calculation, by choosing k-ω model under （0.7~0.9）Qd and the standard k-ε model under （0.9~1.2）Qd .

Abstract:The unsteady full flow fields at shut off condition in a centrifugal pump with specific-speed of 86.44 were simulated by unsteady Reynolds averaged Navier-Stokes approach and SST model. The head of the pump at SOC was predicted based on CFD results. Through the comparison and analyses, it was concluded that the average head prediction errors was 4.7% compared with test result. There were two eddies in impeller flow passage No.1 and the rotation direction was opposite. The velocity at volute diffusion part was very small. The high speed area of the pressure surface in impeller flow passage No.1 increased first and then decreased. The pressure distribution in the volute changes evidently, and the high pressure area of the pressure surface in impeller flow passage No.1 at the exit area constantly decrease as the impeller rotates. There are always six different sizes of vortexes at the impeller inlet and the vortexes nearly block the whole impeller passage.

Abstract:Three-dimensional simulation was performed for the solid-liquid two-phase turbulent flow in centrifugal pumps with particle model and inhomogeneous model separately by ANSYS-CFX software. k-ε turbulence model was applied to predict the liquid-phase, and an algebraic equation known as the dispersed phase zero equation was adopted to predict the solid-phase. All wall boundaries were set as free slip wall conditions. Under the fraction volume of 0.1, the effect of the different diameters (0.1mm，0.25mm，0.5mm and 0.75mm) of solid particles on the slip velocity on the wall of flow-passage parts was studied. The results show that the slip velocity of solid particles increases along with the increase of the particle diameter. And solid particles gradually accumulate near the wall of press surface. There are three places where slip velocity of solid particles is larger and erosion of wall is more serious, such as the head of blade and the blade trailing edge, also the shroud part close to the back pressure side of blade.

Abstract:The unsteady flow of the low specific speed centrifugal pump with curvature blade was simulated numerically by software Fluent, RNG k-ε turbulence model and sliding mesh technology. Three indicator points near tongue with impeller and volute were monitored and pressure fluctuation of those points was gotten. Then, the calculating values were compared with test values. The results show that splitter blades restrain the flow separation. The performance of the pump, the pressure distributions of the pump and jet-wake region are improved deeply. The pressure pulsation amplitude of the indicator points near the tongue is proportional to the distance between the volute tongue and points.

Abstract:In order to study how the leakage flow affect the vibration characteristics of rotors in centrifugal pump and calculate the rotordynamic forces from the unsymmetrical pressures acting on the shroud, the front cavity leakage flow was modeled, and an analysis of numerical simulation of rotordynamic forces arising from the front cavity leakage flow was presented in a centrifugal pump. Firstly, numerical simulation of whole flow field was conducted on a centrifugal pump. Secondly, the simulated results was used as the initial conditions of numerical simulation of the front cavity, and the velocity and pressure distributions of the interior flow field of the front cavity passage were obtained and analyzed. Both normal and tangential rotordynamic forces for various whirl frequency ratios were calculated. Last, rotordynamic forces and all six rotordynamic coefficients were calculated via a second order curve fit, and the results showed that numerical simulation could accurately calculate the rotordynamic forces arising from the front cavity leakage flow.

Abstract:Based on turbulence model of shear stress transport(SST) k-ω, homogeneous multiphase model, and Zwart cavitation model, numerical simulations for high specific speed axial flow pumps with three difference blade number impellers were conducted. External characteristic curves and head performances of cavitation were obtained. Through the analysis, critical NPSHc of three impellers, whose blade number were 3, 4, 5, was respectively 6.19m, 5.122m and 4.765m. In severe cavitation area, the more blades the impeller had, the faster head declined with NPSH reducing. Aiming at the two cavitation type in axial flow pump: fixed cavitation on suction side and vortex cavitation in tip region, the cavitating distribution rule in different NPSH value was found. Compared among three impellers, in the same NPSH, the five blades impeller got smaller cavitating distribution on suction side, which meant lower cavitation degree. However, this impeller would get a sharp head decline when it came to severe cavitation area. Low pressure zone caused by tip leakage vortex moved and expanded to upstream with the decreasing number of impeller blades. Moreover, cavitating volume in the impeller with smaller blade number was larger than the others, and it indicated that this impeller’s cavitation degree was severer than others. So the effect of blades number on different cavitation types and different NPSH was not the same.

Abstract:After structural modification of a submersible sewage pump with a specific speed (ns ) of 60, an experimental study combined with numerical simulation and PIV measurements was carried out in order to analyze the internal flow of the volute. The calculated region was spitted by structure grid and the numerical simulation of whole flow field was performed. The results showed that due to the mouth ring leakage, turbulent kinetic energy was the greatest near this region, and the turbulent kinetic energy in the volute was greater than one in the impeller at the design condition. In addition, comparisons between experiment results of pump performance, PIV test results and CFD computations showed that they were in good agreement, which also validated the numerical result. At last the following conclusions were obtained: affected by the fact that the angle between relative velocity and circumferential direction was became larger with the increasing of the flow rate, when the flow rate was 0.6 Qopt and Qopt , partial fluid in the eighth section return to the first section through the volute, so, there were great velocity and velocity gradient in the region between the tongue and volute inlet. For 1.4 Qopt , this phenomenon disappeared, and at the region near the eighth section, its velocity was maximum, which leaded to a larger velocity gradient. Besides, at the flow rate of 1.4 Qopt , in the region between the first section and the fifth section, three high-speed wake regions from the impeller outlet could be obviously observed.

Abstract:In order to study the design method of high performance compact pump, a high specific speed mixed-flow pump was designed with axial pump configuration by solving the 3-D inverse design equations and the full viscid flow iteratively. Firstly, the performance of the high specific speed mixed-flow pump was calculated using RANS simulation, the results of CFD simulation and test data were presented and discussed briefly. The errors of the mixed-flow pump power between the CFD simulation and pump test data were below 3% in the whole calculating region. Secondly, based on the axial pump configuration, the pump was redesigned by using 3-D inverse design method and CFD simulation iteratively. The final design result indicated that the pump had high efficiency of 0.927 on the design point and the flow within the pump was smooth without any separation and cavitation. In the end, the performance of the mixed-flow pump and the redesigned compact pump were compared, which indicated that the efficiency of the redesigned compact pump was higher than the mixed flow pump by 3%, and the transom size of the redesigned compact pump was smaller than the mixed-flow pump by 38%. The redesigned pump had compact size and excellent performance.

Abstract:he resistance characteristics of air-water flow in spiral pipe were studied experimentally. The influences of mass flow rate and mass quality on pressure drop were analyzed. The empirical formula of the pressure drop was built up based on the method of dimensional analysis and the linear regression with experimental data tested at different conditions. The results showed that the pressure drop increased with the increase of gas-liquid mass flow rate and mass quality. The calculated value of the empirical formula was in good agreement with the experimental data and the formula was accurate enough to calculate the pressure drop of gas-liquid two-phase flow in spiral pipe.

Abstract:In order to meet the requirements of planting techniques of dry-land corn whole plastic-film mulching on double ridges in northwest China, to solve the problems about picked film and tore film and kind of holes with seedlings dislocation caused by the traditional film seeding machine, a direct insert corn precision hill-seeder with whole plastic-film mulching on double ridges was designed. It adopted cam-crank connecting rod mechanism and motion amplification mechanism to control the hole-former sowing and force open in fixed-point. Simulation analysis and field experiment showed that when the direct insert corn precision hill-seeder was planting operation with whole plastic-film mulching on double ridges, the hole-former horizontal velocity component was zero in sowing period and excavating period, the planting distance could be adjusted within a certain range, the arrangement of the soil hole and the hole-former motion trajectory were all reasonable, which met the requirements of agronomic techniques of dry-land corn furrow seeder with whole plastic-film mulching on double ridges.

Abstract:The concentrations of heavy metals Cu, Zn, Cr, Ni, As, Pb, and Cd in pig manure and feed samples were analyzed by randomly collecting pairs of pig feeds and manures samples from 64 pig farms in different regions of Shannxi province, China. The results indicated that the 7 target heavy metals were detected in the pig feed and manure samples. The contents of investigated heavy metals in pig feed and manure samples varied among different farms in different regions. The highest amount of Cu and Zn occurred in pig manure and feeds samples, with the mean contents of 38.33~805.61mg/kg and 90.69~1208.19mg/kg in feeds and 78.99~1543.28mg/kg and 68.72~3011.72mg/kg in manure, respectively. The maximum contents of Cu, Zn, Cr, Ni, As, Pb, and Cd in pig feeds were in 5.44, 34.27, 0.98, 0.08, 10.86, and 7.67 times than the limits in the national standards and are the main source of heavy metals in pig manure. The addition of heavy metals such as Cu, Zn and Cd etc. in pig feeds could lead the serious ecological environmental hazards and would forbid the organic fertilizer farmland application. The farmland heavy metals pollution risk evaluation indicated was conducted by geoaccumulation index method, and the result that farmlands in Shannxi provience have received overloaded manure Cd with the application of pig manures in farmlands.

Abstract:Different water treatments（80%，70% and 60% of field water holding）of summer maize crop coefficient under conventional furrow irrigation and controlling alternative furrow irrigation by using single crop coefficient method FAO recommended were studied. The results showed that irrigation pattern correction coefficient was available to be indicated by the relative amount transpiration and having a good relationship of 6 times a function with the days after sowing. With different furrow irrigation ways，single crop coefficient showed the same pulse fluctuations trend，but in alternative furrow irrigation crop coefficient was smaller than conventional furrow irrigation. The crop water requirement deviations between that calculated by using single crop coefficient method and the measured value were less than 10%，which was in good agreement.

Abstract:Effects of flow rate and opening rate under brackish water film hole furrow irrigation on soil water salt distribution and irrigation performance were studied through a field experiment. Results show that surface water flow advance time and distance conforms to a power function distribution, water advance speed is effected by flow rate and opening rate. Film hole furrow irrigation can effectively regulate soil water salt distribution of 0~40cm by reducing evaporation, inhibiting salt to the surface, soil salt leaching is significant. Ea increases with the opening rate, with the changes of flow rate is not obvious. Ed decreases with the increase of flow rate and the opening rate. With the increase of opening rate, Es increases first then decreases, with the change of flow rate is not obvious. Through variance analysis influence factors of irrigation performance sorting, optimization technology combinations for experimental zone was preliminary obtained.

Abstract:In order to improve the utilization rate of agricultural irrigation water, according to the agricultural irrigation water use, two-steps irrigation was used. The strategy of first stockpile water and then irrigation was applied. Before irrigation every time, in accordance with the DTW-ILC algorithm, the irrigation water was calculated and then stored in the irrigation tank. The calculated irrigation water stored in pool was modified repeatedly close to the actual water consumption in agricultural irrigation. At the same time, the next irrigation water stored in the reservoir could be useful for preventing anhydrous irrigation. The simulation results showed that the actual water use in agriculture irrigation could be tracked well after several times of irrigation process.

Abstract:In order to improve the measurement accuracy of T-TDR sensor and optimize its structure parameters, the rules of the thermocouple node embedded positions and size to its sensitivity and accuracy were studied. Based on the node in the probe middle, midpoint moving down 2mm and reducing the volume thermocouple nodes by spot welding, three kinds of T-TDR sensors and their measuring system were designed. The five different water content of each sandy, sandy loam and clay loam were tested to measure the thermal characteristic curves and calculate its water content. Oven drying method was used to test accuracy. The results showed that the thermocouple on the probe midpoint moving down 2mm and spot welding junction was more sensitive to the radiant heat of the 〖JP3〗intermediate probe than the other sensors. The measurement value of moisture content had good correlation (R2 of 0.981, RMSE of 0.0152) between drying method. The measurement accuracy was higher than traditional structural parameters.

Abstract:For the low efficiency and instability of anaerobic digestion of food waste, the effect of trace elements including iron, cobalt, nickel, selenium, molybdenum and tungsten on anaerobic digestion of food waste was investigated under mesophilic condition (37±1)℃ using CSTR reactors. The results showed that when hydraulic retention time was 40d, organic loading rate was 3g/(L·d), daily methane yield of the reactor with trace elements and control reactor reached to 7.1L/d and 6.7L/d, respectively. The methane concentration in two reactors was 62.7% and 61.6%, respectively. When organic loading rate increased to 4g/(L·d), the methane concentration of the control reactor decreased to 19.5%. However, it could keep stable at around 60% in the reactor with trace elements. Moreover, pH value in the control reactor dropped to 5.24 rapidly which demonstrated the failure of anaerobic digestion process, but it could perform stably at around 7.2 in the reactor with trace elements. A conclusion could be easily drawn that trace elements could improve the methane production efficiency and stability of anaerobic digestion process of food waste under the investigated conditions.

Abstract:Chicken manure, swine manure, wheat straw and corn straw were selected as raw materials for optimization of anaerobic co-digestion based on mixture design and central composite design. Three raw materials in mixture design were independent variables. The ratio of chicken manure and swine manure and the ratio of carbon and hydrogen in central composite design were independent variables. The methane potential was the response variable. The results indicated that the methane potential under co-digestion of three materials performed better than single and two components. The synergy effect of several materials improved the methane potential. Under optimized proportions, the actual methane potential was 1.62, 1.70, 1.66 and 1.73 higher than the expected value. Both mixture and central composite design were suitable for optimization the proportions of raw materials, but central composite design was more appropriate.

Abstract:For the low productivity, high energy consumption and low briquette quality of biomass briquetting machine, the principle of vertical ring die was used. A biomass briquetting machine was developed. A ring mold with heating resistor and cooling waterways was designed. The crushed corn straw was taken as raw materials for the experiment. The experiment result showed that the production rate was 2.1t/h. Tons of power consumption was 35.6kW· h/t. Machine noise was 82dB (A). The molding rate was 95.4%. The forming density was 1.1g/cm 3 . The indicators could reach the design and standard requirements. It could shorten the pre run time by 50min to 65min by using the heating resistor. The ring mold takes cooling device. The temperature of the fuel could be reduced by 20℃ to 30℃ and the production can be increased by 5% than non adopted in normal production.

Abstract:By analysis on influence of machine technical parameters and material parameters on equipment capacity and energy consumption, a theoretical basis for product seriation design can be provided. Capacity and the energy consumption modeling were done, and isolines of capacity and energy consumption at different equipment technical parameters and material properties were drawn, based on the analysis of forming process and mechanics. Isoline distribution show that the greater mould diameter and mould rotation speed are, the more obvious influences of them on capacity and energy consumption become. Compared with other parameters, the frictions coefficient between material and roller as well as between material and circular mould have greater influence on equipment capacity, it can enhance the equipment capacity to improve the surface structure or surface material of the roller and circular mould ; the influence of diameter ratio of roller to circular mould on the equipment capacity was larger than its influence on the energy consumption, the larger the parameter is, the lower the energy consumption for certain capacity becomes, so it is necessary to enlarge the parameter as much as possible.

Abstract:The continuous and highly intergrown CoAPSO-5 membranes were synthesized on the α-Al2O3 substrates by in situ crystallization, which was studied focused on effect of Co content. According to the characterization of scanning electron microscopy (SEM), X-ray diffraction (XRD) and inductive coupled 〖JP2〗plasma emission spectrometer (ICP), the zeolite membranes were composed of well-intergrown CoAPSO-5 crystals, which lost their own morphology and tightly covered on the α-Al2O3 substrate in random orientation. Meanwhile, the Co content of the CoAPSO-5 crystal and its influence on the morphology, the thickness and the completeness of CoAPSO-5 membranes were studied. The gas permeation measurement revealed the resulting membranes were of high-quality with few non-zealitic pores.

Abstract:Bamboo charcoal obtained from pyrolysis was introduced as adsorbent to adsorb model compounds of bio-oil in solution. Single-, double- and four-component of bio-oil was investigated to evaluate the adsorption behavior. The results showed that the adsorption characteristics of each component were different. For single-component adsorption in 24h, the adsorption capacity of each component by bamboo charcoal in declining order was furfural, acetic acid, phenol and glucose. When adsorption equilibrium achieved, the adsorption capacity of phenol would exceed that of acetic acid. In double-component of furfural and glucose system, furfural was showed strongly selective adsorption characteristics by bamboo charcoal. In four-component system, the adsorption capacity of each component was declined especially for acetic acid. Further more, concentration mutation was presented among acetic acid and some component which suggested that the well adsorbed furfural displaced some of the weak adsorbate. The adsorption capacity of glucose was little under all the experimental operating conditions.

Abstract:As a novelty bionic technology, the electronic nose has attracted attention in detection of food and agricultural by-products. Literatures have been reported in the applications of wine, tea, beverage, grain, oil, meat, dairy, vegetables, fruits and so on, showing a well application prospect in food and agricultural byproducts detection by using electronic nose. With the deepening of relevant researches and constantly emerging of new technologies, the electronic nose technology has also been improved. The emergence of new sensor technologies helps to develop electronic noses with completely novelty mechanisms. A more comprehensive detection could be realized integrating the electronic nose with other analytical instruments. A combination of electronic nose and the wireless communication technology, overcoming the limitation that a traditional electronic nose can not be applied to the on-site and mobile environments, expands the scope of applications of electronic nose. This paper aims at making comprehensive discussions and analyses from these three aspects respectively, then summarizing as a reference for the subsequent researches.

Abstract:The object was the short distance transportation refrigerated truck, which belonged to current mainstream in Beijing. A computational model was established for solving the temperature field distribution of the refrigerated truck. The model took the wind speed at the air conditioning outlet, air temperature, cars wall and cargo area temperature of the refrigerated truck as the initial boundary conditions. The unsteady shear stress transport (SST) k-ω model of computational fluid dynamics (CFD) was used to simulate the temperature field distribution on different boundary conditions and stack methods in the refrigerated truck. Under specific boundary conditions with alternating the wind speed in the outlet and the cargo stack mode, the model could determine the best outlet wind speed and stack way of cargo through comparative analysis. The results showed that when the wind speed was 5m/s and stack methods was void in the middle and two sides, the temperature field distribution in the refrigerated truck was the best uniform. The tests showed that the simulated values were in a sound agreement with the measured ones and the average absolute error of the temperature was not higher than 1℃.

Abstract:Using N2 as drying media to replace air partially has the potential of getting a more rapid drying process and a better product quality. The N2 -air mixed gas state parameters were calculated and a humidity-enthalpy chart relating all the relevant variables was developed. Heat transfer coefficient and mass transfer coefficient parameters were predicted according to theoretical calculation. State parameters and mass transfer coefficient for the N2 -air mixed gas were found to increase with increasing N2 content, whereas heat transfer coefficient decreased with an increase in N2 content.

Abstract:In order to design the high-oxygen modified atmosphere packaging in mushroom (Agaricus bisporus), Weibull model and Logistic model were applied to study in-package O2 and CO2 concentration and predict the respiration of mushroom. The results showed that O2 concentration in high oxygen package decreased from initial 80kPa to 50kPa after 50h, while it declined slowly in control. The CO2 concentration under both treatments increased gradually, and it reached the maximum value at the end of storage. The predicted concentration of O2 and CO2 fitted well with the experimental value. The respiration of mushroom under high oxygen was well described by the CO2 production rate.

Abstract:With the aim to improve the efficiency of hot-air drying, a dryer of hot-air drying combined power ultrasound was explored according to the advantages of ultrasound on enhancing heat and mass transfer and the acoustic impedance of flexural vibrating plate. In this dryer, ultrasound could work effectively in air. The results of mushroom slices drying showed that the drying time using hot-air drying combined power ultrasound at 20kHz, 150W and diameter 20cm plate was shorter as 50% as that using hot-air drying and the energy consumption per kilogram of water evaporation reduced by 22%. The mechanism of ultrasound which enhanced hot-air drying was discussed. It was possible attributed to ultrasound mechanical actions to enhance the moisture diffusion controlling step in the drying processing.

Abstract:Aimed at the problem of litchi drying performance is restricted by its shell pore structure, each side of the shell pore shape was observed by electron microscopy and its average porosity was calculated by Image-Pro software. Through building a model of water evaporation at high temperature, heat and mass transfer coupling for litchi multi-layer structure, using the Fluent software to simulate the temporal variations of temperature, pressure and velocity in litchi drying process, the difference between simulation result of water volume fraction in this process and experimental value was compared. The results show that the pore structure exists a self similarity in each surface of litchi shell, average porosity is 0.516±0.032; when litchi is dehydrated at 70℃, temperature of the fruit body conducts from shell towards its interior and reaches the equilibrium state gradually; a negative pressure is gradually increasing on its inner surface; water vapor on the flesh surface is with low velocity and small pressure difference, but with the time increase of loss water, the fluctuation of vapor velocity and differential pressure increase too. It’s showed that the simulation result can be better corresponded with the experimental value. These research results would provide a reference for other multi-layer structure fruit drying process.

Abstract:Defatted soybean meal was employed as an original material to get β-conglycinin (7S) through separation and purification. And 7S was grafted with maltodextrin by using ultrasound-assisted to modify its properties. Taking the emulsifying activity (EAI) and emulsion stability (ESI) of the modified products as indexes, Box-Behnken model was used to optimize reaction conditions. In addition, SDS-PAGE electrophoresis and scanning electron microscope (SEM) analysis were also investigated to verify that 7S molecule was grafted with the saccharide molecule. Response surface analysis revealed that the optimized modified conditions were as follows: the amount of maltodextrin of 9.5%, ultrasound time of 30min , ultrasound power of 450W. On these conditions, the emulsifying activity index (EAI) and emulsion stability index (ESI) reached to 1.142 and 27.13min, which were 60.59% and 57.06% times against the native β-conglycinin, respectively.

Abstract:Effects of the pulsed magnetic field on membrane fluidity of Bacillus subtilis were investigated. 1,6-diphenyl-1,3,5-hexatriene (DPH) was used as fluorescence probe to label the membrane of B. subtilis at 35℃ for 45min to determine the changes of fluorescence polarization and fluorescence anisotropy of B. subtilis membrane by fluorescence polarization technique. The results indicated that fluorescence polarization and fluorescence anisotropy increased with the increase of intensity and pulse number of PMF. Compared with the control group, fluorescence polarization increased greatly at 2.0T with 25~30 pulses, 2.5T with 25~30 pulses, 3.0T with 20~30 pulses and 3.3T with 10~30 pulses（P＜0.05）. Fluorescence anisotropy also increased greatly at 2.0T with 30 pulses, 2.5T with 25~30 pulses, 3.0T with 20~30 pulses and 3.3T with 15~30 pulses（P＜0.05）. The membrane fluidity decreased, resulting in the lost of the membrane function, when treated by PMF, which suggested a perhaps mechanisms for the cell death.

Abstract:As one of the key problem for the robotic harvesting, the real-time recognition and localization of fruits and vegetables in field have drawn wide attention. First, the development of common hardware and algorithms for the recognition of fruits and vegetables was reviewed. For the image segmentation of fruits and vegetables, researches on image preprocessing, color feature selecting, image segmentation designing and image post processing were summarized and analyzed. For the recognition of fruits and vegetables, researches on common algorithms, recognition algorithms for clustered objects and for occluded objects were reviewed. Second, active and passive range finder methods which have been used commonly in the localization of fruits and vegetables were analyzed and compared. Moreover, stereo matching methods used in the passive range finder methods for fruits and vegetables were analyzed and compared, too. Finally, existing problems in researches on the recognition and localization for fruits and vegetables in field were analyzed, and research prospects were also presented.

Abstract:A device was developed on the basis of the full investigation of biological culture devices in international space vehicles. According to the plants in different growth stages, the parameters of space culture devices could be adjusted automatically by PC software. The temperature, humidity,carbon dioxide and ethene in plant growth chamber were controlled by using semiconductor heating element. It provided adequate water and nutrients, appropriate light intensity and duration. The image information was acquired. It also had the function of gas exchange and condensate water recovery. System test showed that this method was feasible. The control precision could meet the requirements of plants. The fluctuation of parameters, such as temperature, humidity, ethylene and CO2 , was within the range of plant growth needs.

Abstract:The typical characteristic values of electrical signals in plant from time domain, frequency domain and time-frequency domain were analyzed and the electrical signals in plant were to be as physiological indicators. To establish environment prediction models, typical features of electrical signals and some environmental parameters were chosen to be as input of neural network with the extreme learning machine algorithm characterized by fast learning speed and good generalization. The results showed that the plants electrical signals were the low-frequency weak signals by analysis of the electrical signals in Peperomia tetraphylla leaf on different domains, and by extreme learning machine three prediction models such as temperature, humidity and illumination were established to make plants grow well. Compared with the traditional BP neural network, the root mean square error with ELM algorithm is less than 0.97, while the coefficient of determination is more than 0.92 and each training time is less than 0.03s. This method provided the scientific basis for greenhouse environmental regulating and was verified to be feasible.

Abstract:In order to meet needs of information acquisition and processing of the vehicle-borne system, a crop growth spatial analysis software for vehicle-borne system was developed. The software system was composed of four functional modules: spectrum file management, canopy spectrum analysis, dynamic monitoring and spatial data analysis. It could read a variety of file types. It also could apply two kinds of spatial information analysis methods and had an interface for expert database. The proposed system was set on crop growth spatial platform to verify the effect of growth spatial analysis system for corn. Field test results showed that the system could generate crop and wheat growth distribution map and interpreted working prescription map correctly. It indicated that the system provided good technical support for the precision management of field crops.

Abstract:The plant detection methods were studied by field pictures of rice and image processing. Combined improved normalized difference index of blue-green IDNBG and chromatic model, extracted of plant leaves were extracted by classification, recognition and image threshold segmentation. Forward and reverse morphological operation was used to repair integrity of inside blade. 4-connectivity chain code was used to detect leaf edge and repair smoothly. 40 pictures were taken under the conditions of visible and field. The average correct extraction rate of plant leaves was 83.07%, and the average error extraction rate 3.57%. 90 edge lines were repaired smoothly which resulted in the reduction of correct extraction rate of leaves by 0.63%. The main factors of plant detection were analyzed. It showed that imaging different conditions affected the brightness factor which served as main factor of chromatic model. Morphological dilation operator and forward and reverse filter operator remained some small dew and lesion, so that inside of extracted blade was complete. The chain code could smooth the blade edges and remove some part of correct blades.

Abstract:A suspension-weighing lysimeter was developed with weighing capacity of 100kg in order to study the evapotranspiration of the potted plants conveniently and effectively. The method of integration and optimization between slave microcontroller and host computer were used. The lysimeter was mainly composed of six parts, weighing sensor, slave microcontroller, host computer, adapting pieces, stand and plant pot. Slave microcontroller of lysimeter includes a microcontroller, data collection and display modules, real time clock, storage module, communication and power modules. The circuits for these parts were designed. Performance tests showed that without human supervision, the slave microcontroller was able to automatically collect, display, store and communicate data through serial interface to the host computer and then the host computer displayed, stored and analyzed the transmitted data. The results showed that the absolute and maximum relative error of lysimeter were 100g and 0.50%, respectively. The ET results of potted plant obtained with the instrument were proved well matched with their actual ET of potted plants with time. It could meet with the requirements of convenience, high accuracy and real time in ET measurement.

Abstract:For the problem of real-time path optimization for picking robot manipulator, an improved artificial potential field method was presented for apple picking robot manipulator to avoid obstacle under unstructured environment. According to the concrete structural characteristics of 5-DOF apple picking robot manipulator and obstacle, the manipulator model and obstacle model were analyzed. On the basis of retaining the merits of the traditional artificial potential field method which had simple structure and easy implement, for some of the shortcomings of its existence, such as local minimum points, the stuck district, combined with the characteristics of obstacles in the apple growing environment, a virtual target point was introduced to help the search process escape local optimal minimum point and obtain an optimization smooth motion curve. This method was applied in the obstacle avoidance path planning experiment for the apple picking robot manipulator, which included end-effector, obstacle and targets position. The experimental result showed that the proposed method was simple and enabled to overcome the shortcoming of traditional artificial potential field method.

Abstract:Mechanical properties of plug seedlings related to auto-transplanting were analyzed by tests of clamping seedling to pull it out, friction tests of the plug seedling bowl and the plane compression tests of the bowl, which provided the basis for mechanism design. Technical design of the auto-picking seedling was carried out in order to acquire the theoretical relationship between pulling force, compressive strength of the bowl, gripping angle, gripping size and friction coefficient for the picking seedling end-effector of two-needle gripping type. The picking seedling end-effector adapting to mechanical properties of plug seedlings was designed according to the mechanical characteristics of plug seedling by using gripping parameters relationship. Gripping forces were studied by the physical prototype testing. Test results showed that there was no significant difference between gripping force testing data and calculated data, which demonstrated the reliability of the theoretical design. When the frequency of picking seedlings was 30 plants per minute, the success rate of picking seelings in the testing moisture contents was up to 95.16%.

Abstract:Aiming at removing complex soil background noise in the corn seedling filed, a color image segmentation algorithm based on MMC (Maximum margin criterion) and CV (Chan-Vese) was proposed. The corn color image was transformed into gray image by using MMC, and the grayscale image was denoised by TV (Total variation) filter. Then filtered image was segmented by the CV model. The results of the experiment by Matlab showed that the algorithm could effectively get the extraction of the objection of corn and noise reduction of weed and moss simultaneously in the image. The misclassification rate and the leakage rate were 4.32% and 9.69% respectively, and the similarity was 86.57%.

Abstract:The application of digital photographic method in the forest has shown great potential for improving the accuracy and efficiency. Image acquired with acommercially available digital camera were used to make measurements on 10 Platanus orientalis stems. Laser spot was used as scale instead of pole. The laser spot was extracted from the background by the 2-D Otsu algorithm. Error studies showed that the laser spot should be set at 1.3m high to improve the measurement accuracy. The accuracy of this method for measuring diameters at breast height was tested by comparing the results with those obtained from caliper. The comparison showed that the photographic method provided a good assessment of standing tree diameters at breast height and the maximum error was 1.22%.

Abstract:To acquire the properties of ear characters in maize automatically, a panorama of the maize ear was captured by using a line scan camera. Then the data was extracted through image processing methods. A part of the original line scan image was selected as a template. The ear image with exactly 360° views was cropped according to the normalized cross correlation of the template with the original image. Otsu method was used to segment the maize kernels, but the kernels on the image borders were split into two parts. The connectivity of those two parts of one kernel on both borders was taken as a clue to merge them into ones. This process improved the counting accuracy of kernel numbers. The row number of the kernel was obtained from the image projection method. The profile of projection was smoothed to solve the extreme points as the row number. Experiment results showed the counting accuracy of kernels numbers and kernel rows numbers were 94.6% and 99.1%, respectively.

Abstract:Dimensionality reduction approach was proposed based on anisotropic kernel diffusion map to extract the features of poplar leaves, in which the kernel parameters were adjusted adaptively. In order to improve the accuracy and efficiency, singularity points were removed and features normalization method was employed to obtain the robust features. The maximum margin criterion method was utilized to obtain anisotropic kernel parameter by gradient descent method. The results show that the anisotropic kernel diffusion map has good performance on efficiency for poplar leaves compared with LE, LTSA and PCA. The comparisons of classification experiments have been conducted, by using SVM (support vector machine) classifier to recognize the water shortage of poplar leaves, and the results validate the accuracy and stability of the proposed method.

Abstract:A quality grading method based on sparse representation was proposed to identify the varieties of tobacco quality. The images of 17 different qualities of tobacco were taken as objects. Ten images of each variety were selected randomly as training samples. The colors, morphological and textural characters of these images were extracted for making up the dictionary of sparse representation. The projection of the test image on the dictionary was calculated. The minimum projection error was regarded as the certain kind of tobacco. The result of the proposed method was compared with basic pursuit algorithm, neural network, SVM and fuzzy processing. The identification accuracy of training samples was 100% and the overall one was 95.7%.

Abstract:Due to the friction, serial robots with harmonic drives may appear rough running and control precision deterioration at low speed. To deal with this problem, a desired compensation robust controller (DCRC) with friction compensation was constructed. First, based on the frequency domain analysis of the friction data, a new friction model, which is the combination of Stribeck model and sine/cosine functions, was involved to model the friction of harmonic-drive-based joint. Second, DCRC was designed to handle the effect of joint friction and model uncertainties. In this control scheme, a feed-forward term calculated off-line using desired motion data was designed to avoid introducing measurement noise and improve the real-time performance. In this term, the joint friction compensation was also included. A robust term was designed utilizing the bounds of the uncertainty to guarantee the robustness. In addition, the globally uniformly ultimately bounded stability of the resulting closed-loop system was proved by using Lyapunov theory. Finally, experimental results illustrate that adopting the proposed friction model and controller, stable trajectory tracking at low speed can be achieved, and the average tracking error in joint space is less than 0.005°.

Abstract:In order to get the structural dynamic of the high speed ball screw driven servomechanism, a hybrid modeling method was proposed. The proposed model took the axial, torsional and bending vibrations of the screw into consideration by the Euler-Bernoulli beam elements with axial and torsional theories. The servo subsystems and the other more rigid components were modeled by the lumped parameter method. The flexible ball screw feed drive servomechanism was proposed, including the friction, backlash and the cutting disturbance. Compared with the experimental results, the hybrid model could accurately capture the structural dynamics of ball screw drives. Numerical simulation indicated that the nonlinearities of friction and backlash could cause velocity fluctuations at the low speed. The torsional and axial vibrations made the servo system unstable, especially in the high speed application.

Abstract:The kinematics of a 4-SPS/CU parallel mechanism was analyzed. In order to quantitatively analyze the influence of joint friction acted as non-conservative force on the mechanism dynamics, the calculation of the normal force corresponding to joint friction was important. For simplifying the dynamics model, the driving chain was treated as a rigid body so the driving friction could be seemed as internal force. Based on the “Coulomb + viscous” friction model, the dynamics model with joint friction of up platform, driving chain and driven chain were built respectively by using Newton-Euler formulation, which could obtain the joint constraint forces/torques with giving motion trajectory of the mechanism’s up platform. Subsequently, the driving friction models were established on account of the relationship between the driving chain’s normal forces and joint constraint reactions. The iterative procedure of complicated dynamics equations was formulated for the effective simulation. The research results showed that joint friction forces significantly impacted on the driving forces of the mechanism.

Abstract:In order to solve the problems of kinematics coupling, a method was put forward based on kinematics. Kinematics coupling mechanism of 3-PTT series-parallel machine tool servo feed system was analyzed. Based on hooker and motion characteristics of series, parallel institutions pose decoupling method was used for analysis. The ADAMS and Matlab were used for simulation. The results showed that this analysis could reflect the kinematics coupling of 3-PTT CNC serial-parallel machine. It had high velocity and small coupling error. The research process could effectively solve the problem of series-parallel CNC machine tool servo feed system kinematics coupling.

Abstract:The parallel mechanism of 4-SPS was studied. 2T2R (2 translational and 2 rotational) 4-DOFs (degrees of freedom) parallel mechanism were obtained by configuration evolution of adding and altering the follower-limb. The constraint condition of solving the position and attitude workspace about 4-SPxyz S/PxPzUxz parallel mechanism was built. The set of points was used to calculate dimensional size of workspace. The concept of sensitivity was introduced. The numerical method was used to calculate dimensional size of position workspace and scope of attitude workspace in the solution of different scale.

Abstract:The variable step size database method for the function synthesis of spherical four bar crank slider mechanism was presented. Based on the analysis of input and output function of the spherical four bar crank slider mechanism, the immanent connection between output function and its corresponding harmonic characteristic parameters was discovered. Based on this discovery, a numerical atlas with variable step size database of output angle function, which contains 42185 groups of basic dimensional types, could be created by the harmonic characteristic components and associated basic dimensional type of spherical four bar crank slider mechanism. The best suitable basic dimensional type of spherical four bar crank slider mechanism for prescribed function was decided by using fuzzy identification method and numerical atlas database. Thus the function synthesis of spherical four bar crank slider mechanism was made possible. In order to improve the precision, the result could be optimized by genetic algorithm. The ventilation device of the greenhouse was taken as an example to illustrate the analysis process and application of this method.

Abstract:An approach was proposed for the optimal dynamic design of a 4-DOF palletizing robot with closed-chain. On the basis of rigid body dynamic model, a dynamic optimization objective was proposed to minimize the maximum driven torque based on target trajectory and determined motion law. Based on this, a multi objective planning problem under certain constraining condition was constructed and then through shortest distance ideal point method converted to single-objective optimization problem. An example revealed that the robot’s dynamic performance was great improved by optimizing the robot’s scale parameter. The decreasing range of upper and lower arm’s joint torque peak were 9.782% and 8.207% respectively, which show that the optimal dynamic design method is reasonable and effective.

Abstract:Instead of eccentric wheel vibrator and plane screen, a new design ideal was presented to take parallel mechanism and non-planar screen as drive source and screen, respectively. With the multi-dimensional spatial movement of parallel mechanism and the multi-dimensional permeability of non-planar screen, it can increase the screening efficiency. A parallel kinematics vibration sieve based on single DOF and two loops spatial mechanism was designed, then the topology structure of its main mechanism and kinematics based on the track of screen was analyzed and its dimensions were optimized. The design of non-planar screen and the principles of its multi-dimensional permeability was illustrated and the experimental effects of parallel kinematics vibration sieve and traditional line vibration sieve with planar screen, wave screen and pit screen were compared respectively, which verify that the screening efficiency of parallel kinematics vibration sieve with non-planar screen is as high as 98%, and the permeability is 7.4%, while the screening efficiency and permeability of line vibration sieve with planar screen is just 84% and 5%, respectively. So the efficient screening mechanism and characteristics of this new parallel kinematics vibration sieve can be revealed.