Abstract:The stretching separation and coalescence are only considered in the O’Rourke model while the bounce, reflexive separation and the secondary breakup under high Weber collision are ignored. Furthermore, the influences of droplet property and collision condition on the collision regimes are not included in the O’Rourke model so that the predicted critical Weber numbers are underestimated. In the composite collision model, the collision regimes were revised to consider the influence of droplet viscosity and environmental pressure, and the bounce, coalescence, reflexive separation, stretching separation and the secondary breakup under high Weber collision were also considered. Moreover, the influences of droplet viscosity and environmental pressure on the spray collision were investigated based on the composite collision model. The results showed that the probability of bounce was increased due to the increasing of environmental pressure while the probability of coalescence was decreased. However, the probability of coalescence was increased with the increasing of droplet viscosity while the probability of collision separation was reduced.

Abstract:The main components and properties of physics and chemistry of Jatrapha curcasl oil were analyzed. The characteristics of performances, combustion and exhaust emissions of a ZH1115 diesel engine using different fuels were measured. It is found that when the engine using Jatrapha curcasl oil, the cylinder pressure, the pressure rise rate, emissions of NOx and HC, and the exhaust temperature were all lower than using diesel, the smoke was at equivalent level; however, the CO emissions was higher. The cylinder pressure and pressure rise rate and its NOx emission increased, but when the advance angle of fuel supply increased, the exhaust temperature decreased a little, the CO emission had little change, and HC emission reduced.

Abstract:There is close connection between vibration signal and combustion status before peak pressure. Comparison was carried out among the vibration acceleration signal, cylinder pressure, rate of pressure rise and pressure rise acceleration before peak pressure. Based on the similar trend waveform, a novel method using inflection of vibration acceleration to estimate combustion process feature points was proposed. Contrast was also carried out among cylinder pressure, rate of pressure rise, time domain waveform and frequency component amplitude of vibration acceleration and pressure rise acceleration. Results showed that the maximum time domain fluctuation and frequency component amplitude of vibration acceleration are closely related with combustion status and the information can be used as characteristic parameters to reflect combustion status. Experiments were carried out and the result verified that the characteristic parameters were feasible.

Abstract:Based on nonlinear time-delay mean value idling mode of GDI engine, aiming at torque interfere generated by auto accessories using of electricity under idling mode, the delay-dependent H∞ state feedback controller was designed. It did not only guarantee the closed-loop control system asymptotic stability, but also met suppression ability as γ about the output to disturbance input. The delay included induction-to-torque delay under steady state of engine, delay between time of air input controlled by air throttle to actual time of this section into the cylinder under transient state of engine, also included delay of the action of the air throttle. The time-delay which was discussed was all uncertain time-invariant, but each had a constant upper bound. Finally, the modeling correctness and validity of control method was verified by using the exact engine model established by en-DYNA software. Compared with control effects of controller without considering delay and delay-independent controller which was designed with considering the time-delay problem，the integrated control effects of delay-dependent controller designed by this research is the best .

Abstract:With the aim to improve the accuracy in transient A/F control for spark ignition engines, fuel film model was widely used. The traditional identification methods of the fuel film model were reviewed. To faster parameters identification process, a decoupling auto-identification method was presented. The result of simulation showed that the proposed method was valid. Finally, a theoretic two-equation algorithm, which could calculate the fuel film model parameters directly, was introduced. 

Abstract:With the simulation of the flow in hydraulic machinery, experiments of cavitation, silt abrasion and their synergism on hydrofoil in the converging-diverging testing section were performed, and microscopic appearance along the damage surface was observed and depth distribution of damage was measured. The cavitation appearance shows like normal approximate round, and distributes randomly. According to the difference of action parameter on surface, silt abrasion appearance registers as wedging，relieving，ploughing, and cutting, etc. On the high particle content, the appearance of synergism mostly appears as particle wear in extreme angles (90° or 0°), and scale character on hydrofoil surface becomes more and more large than silt abrasion appearance along the position, and the depth of macro-damage is obviously bigger than single wear. On the low particle content, the microstructure probably appears as the coexistence of cavitation and silt abrasion.

Abstract:The influence of relationship between wrap angle of impeller on performance of a pump was analyzed with the same main dimensions of centrifugal pumps unchanged. Blades were shaped using Hermite interpolation method. The wrap angle of impellers used in this investigation is 90°, 120°, 150°and 180° respectively. The result of numerical simulation indicates that the wrap angle changes the head and power characteristics by changing the relative velocity angle in impeller outlet. The effect of the different wrap angles is similar to that of the different impeller outlet blade angles. The bigger the wrap angle is, the smaller the separation and vortex in impeller passages are. With the wrap angle increases, the streamlines and blade profiles are getting similar, but the friction loss in impeller passages is getting large. So there exists an optimum wrap angle that corresponds to the highest efficiency of a centrifugal pump.

Abstract:The research was conducted for the purpose of studying the rules of pressure fluctuation under different positions in a centrifugal pump, and to find their relationships. The frequency spectra of pressure signal located at the pump was obtained with CFD. The results showed that the blade passing frequency dominated the pressure fluctuations at the design and large flow rate condition, and at the small flow rate condition the axis frequency became dominative in the pressure fluctuations. The amplitude of the pressure fluctuation was different at the varied flow rates, and the amplitude became higher at inlet and outlet of the passage.

Abstract:An experimental system was established for the performance test of the developed prototype of electric motor pump. The parameters consisting of the electric power input, hydraulic power output, rotor speed and internal pressure in the electric motor pump were measured. The characteristic of the rotor speed, noise, power and efficiency changing with the outlet pressure of the prototype was obtained. Compared with the traditional hydraulic power unit which has the same power as the prototype, the volume of the prototype was reduced by 50%, the dimension in axial direction shortened 61% and the noise level lowered 7dB, and the speed of rotor in the prototype decreased apparently with the increased of the output pressure. Furthermore, the bubble separation as a result of the narrow channels and the extra leakage due to the ineffectual seal in the prototype were discussed, and the corresponding solutions were proposed. 

Abstract:The application of the BP and RBF artificial neural networks in energy characteristics prediction of centrifugal pumps was summarized. The structure and characteristics of the two artificial neural networks were introduced in detail. The models of BP and RBF artificial neural network were established respectively to predict the centrifugal pump energy characteristics. The characteristics data of 57 centrifugal pumps were used to train the two models, and the data of the other 6 centrifugal pumps were used to test the two models. The study shows that the prediction results of the two networks are closer and the trends of prediction results are the same for the two networks. The precision of BP network is a little higher than that of RBF network. The head average prediction discrepancy for BP network is 3.85% and the efficiency average discrepancy is 1.39% points. The head average prediction discrepancy for RBF network is 4.79% and the efficiency average discrepancy is 3.43% points. The prediction time of RBF network is only half the time of BP network.

Abstract:The experiments on changing the axial location of impeller and measurement of flow field in volute with five-hole probe were conducted on a self-built vortex pump (32WB8-12). Based on the experiments, the qv-H, qv-P, qv-η, qv-NPSHc curves and the absolute velocity v, the circumferential velocity vu, the radial velocity vr, the axial velocity vz and the flow static pressure ps were obtained. The experimental results proved that the qv-NPSHc curve showed opposite tendency in the operating conditions of small charge compared with centrifugal pump and anti-cavitation were improved with the increase of the scale S that impeller was inserted into volute. The investigation also showed that the axial vortex was dominant flow in volute but with back-flow existing at the same time. The relationship between performance and parameters of the internal flow and the suction, head formation principles of vortex pump was explained. 

Abstract:In accordance with the characteristics of a long water pipe supply system with water hammer, the analysis of the protecting devices combined with the air valve, pressure relief valve and slowly closed plate valve was carried out for the transient process caused by accidental pump-stop based on the theory of water hammer and the method of characteristics. The pressure of water hammer and relative cavitating volume along the pipeline were obtained simultaneously. The evolvement of pressure of water hammer against time was achieved. The numerical results showed that the present water hammer protections to the pipeline system were necessary, which restrained not only the continuously rising up but also the excessively decreasing of water hammer pressure and were helpful to suppress the occurrence of water column separation. However, the results also showed the cavitations in local raised position of pipeline. The optimization of the position about air valves should be implemented further. 

Abstract:For the sake of rational exploitation and utilization of shallow layer underground saline water, through laboratory infiltration experiment in Nanpi Ecological Experimental Station of Chinese Academy of Science, soil moisture content, salinity, desalting efficiency and cation distribution were analyzed with saline water of 3g/L. Its purpose was to study the soil infiltration characteristics irrigated with saline water in North China. The results showed that under the vertical one-dimensional ponding infiltration with saline water of 3g/L, matric potential was the main driving force of water movement when the infiltration amount was comparatively small; gravity potential gradually replaced the matric potential to become major driving force for water movement when infiltration amount became lager; upper soil would be desalted and soil salt content would increase to reach maximum infiltrated with saline water of 3g/L; relationship between soil salt content in wetting front and infiltration amount according with the exponential function, desalting efficiency of active rooting zone negatively correlated with cumulative infiltration. In short, with saline water was used in farm irrigation, both the effect of salt leaching and the desalting efficiency must be considered to make soil used sustainably.

Abstract:In view of the existing low efficiency of method problems about the optimization of water allocation of canal system, a multi-objective model about optimization water allocation was established to acquire the highest increased yield benefit and water income of the irrigation district under the basic of soil moisture and the water production function. The information of land use and soil moisture in irrigation area was gained easily by RS technology. The optimization water allocation in each branch under the condition of multi-objective could be obtained by the model solution with ant colony algorithm in GIS system of each the image pixeles. The result accorded with the practical situation of water use in irrigation area. Therefore, this model can be widely used for decision makers to optimize water resources distribution. 

Abstract:Evaluation of comprehensive benefit was conducted in greenhouse muskmelon under aeration irrigation by applying comprehensive evaluation method, which associated entropy information method based on objective weighting with subjective weighting method. Results showed that the comprehensive benefit order in every treatment was once per two days, once per day, none aeration, once per three days, twice per day, and furrow irrigation treatment. Aeration irrigation could improve yield and quality of greenhouse muskmelon differently, but the comprehensive benefit of some aeration treatments decreased because of the investment of electricity, drip facility, et al. The comprehensive benefit of greenhouse muskmelon in subsurface irrigation treatment was better than in furrow irrigation treatment. 

Abstract:Using SWAP (soil-water-atmosphere-plant) model and dual crop coefficient approach presented in the FAO irrigation and drainage paper 56 (FAO-56, 1998, crop evapotranspiration, guidelines for computing crop water requirement), the evapotranspiration of the natural vegetation in Otindag Sandy Area was calculated. The main results indicate that SWAP model and dual crop coefficient approach can be used to simulate evapotranspiration. SWAP model can simulate soil profile soil volumetric moisture. 

Abstract:A new burner, named PB-20 biomass pellet fuel burner, was developed at the Chinese Academy of Agricultural Engineering to solve the problem of easy flameout and slagging of burner during pellet combustion as there were higher ash and lower ash melting temperature in the pellet made of crop straw in China. The double combustion cylinder efficient device which adopted multi-level wind principles, a helix device breaking slagging and cleaning ash were designed. Combustion experiment with the corn straw pellet fuel and larch wood pellet was conducted after this pellet burner was made. The results showed the burner worked well and the ash and slagging were expelled because of double combustion cylinder efficient and helix device. The slagging rate is 23% and the combustion efficiency is up to 91%. The slagging rate of PB-20 biomass pellet fuel burner decreased by 25.94% and combustion efficiency increased by 9% compared with burner made from Sweden. 

Abstract:Taking the physical model of downdraft biomass gasifier as the research object, fluid simulation software Fluent was used, the pressure field of the gasifier that in the condition of single-layer air-distribution and double-layer air-distribution was comparatively analyzed. By means of multi-point pressure measurement experiment, the simulation results were verified. The Euler-Lagrange model was used to analyze the cold characteristics flow field distribution of gasification. The reason of diversification in pressure field by Bernoulli’s equation was discussed. The results showed that the deviation value of simulation and experimental results was under 2.5%. Different air-distribution condition should lead to the changes of flow field in biomass gasifier. Double-layer air-distribution condition made the average pressure in oxidation area of 14.98kPa, higher than that in the condition of single air-distribution. And also the axial direction pressure distributed equally. 

Abstract:Definition and characteristics of distributed combined cooling, heating and power system (CCHP) were briefly summarized. The principle of biomass gasification system was mainly introduced, and several application modes of CCHP based on biomass gasification (BGCCHP) were discussed. At last, the advantages and difficulties of developing BGCCHP in China were analyzed. BGCCHP could realize the cascade utilization of energy coming along with social, economic and environmental benefits and it is an efficient and comprehensive way for biomass resource exploitation and application. 

Abstract:The change law of dielectric properties on Fuji apple superficial scald which stored at constant temperature was investigated. The mechanisms that reflected internal quality of fruit using dielectric properties were discussed so as to provide a new theoretical basis for nondestructive inspection and research methods to distinguish between diseased and normal fruits based on electrical properties. The fruits’ dielectric properties, which embraced the impedance, reactance, conductance, capacitance and loss coefficient, were determined with going up frequency from 100Hz to 3.98MHz at (20±1)℃ by applying LCR electronic measure instrument. The results showed that with the frequency increasing, fruit impedance and reactance were decreased; the capacitance and dielectric loss coefficient were changed irregularly, while the conductance was increased in spiral form under same storage times. There was a significantly positive correlation between impedance and reactance, the value of capacitance were significantly different (P<0.01) between the diseased and normal fruits from 100Hz to 3.98MHz. The research revealed that the capacitance could reflect the quality of apples in some extent. 

Abstract:To study the influence of sesame protein isolate on cheese system, the characteristics of microstructure and thermal properties of cheese contained sesame protein isolate were investigated. Cheeses made from mixture milk with 0, 4%, 8%, 12% protein substituted by sesame protein isolates in total milk protein were prepared. Adding sesame protein isolate in cow milk resulted fat globular smaller and more regular, showed the emulsifying and homogeneous properties of sesame protein isolate. DSC analysis showed the thermodynamic properties were influenced by sesame protein isolate, one new absorption peak was detected and the peak temperature varied with sesame protein isolate content. The interact mode of sesame protein isolate and casein based on the present results were discussed and the research results were published. 

Abstract:In order to determine the effectiveness of O3 on lignification of bamboo shoot (Phyllostachys pubescens Mazel), the bamboo shoots were exposed to either 100μL/L, 200μL/L or 300μL/L for 30min before stored at (1±1)℃ for 30d. The effect of O3 treatment on lignification and related enzyme activity were investigated. The results indicated that O3 treatment inhibited firmness from increasing, while decreasing the respiration rate and ethylene production. O3 treatment also retarded the activities of phenylalanine ammonia lyase (PAL), peroxidase (POD) and polyphenol oxidase (PPO) increasing. The cellulose and lignin content were 8%~14% and 7%~12% lower than that of control, and the dacay rate was 71%~84% lower than that of control. Therefore, O3 treatment has potential use in delaying lignification of bamboo shoot. 

Abstract:DPPH自由基的EC50值为0.217g/(100mL)。Protease screening was employed to prepare rice anti-oxidation peptide with enzymolysis method. Scavenging rate of hydrolysate to the DPPH radical was used as an index with rice protein as the raw material. Neutral protease was screened out from the following seven kinds of protease. These kinds of protease were flavor protease, neutral protease, trypsin, complex protease, alkaline protease, papain and pepsin respectively. The optimum hydrolysis conditions obtained from the experiments were as the following: concentration of substrate was 1.0 g/(100mL), ratios of enzyme-substrate was 8%, pH value 6.0, 60℃ and 30min of reaction time. After being diluted 15times, scavenging rate of hydrolysate liquid to the DPPH radical 89.45% could be obtained and EC50 value of hydrolysate scavenging DPPH radical was 0.217 g/(100mL). 

Abstract:Bovine bone was used as the raw material to extract collagen by the high-intensity pulsed electric fields. The optimal processing conditions were acquired by the single-factor experiments and the Box-Behnken experiment. The most yield of dissoluble collagen 16.21mg/mL was achieved under the following conditions: substrate concentration 1.0g/(100mL), pepsin concentration 3%, pH value 2.5, electric field intensity 21.98kV/cm, electric pulse number 7. The extracted collagen was identified by UV spectra that it was the pure collagen protein and did not contain other miscellaneous proteins. 

Abstract:A portable visible (Vis)／near infrared (NIR) spectrometer was performed on pears (Pyrus communis L.) cv ‘Abate’, ‘Conference’ and ‘Wujiuxiang’ for firmness assessment by diffused transmittance technique. One set of 96 pears were used to explore the performance of this technique on developing global firmness models with partial least squares (PLS) and multiple linear regression (MLR) methods. The spectra were treated by 2nd order derivation with Savitsky–Golay (polynomial order 2, data point 25). Genetic algorithms partial least squares (GA-PLS) and regression coefficient method were used to select informative variable for PLS calibration. The global models were obtained by PLS to predict firmness yield the root mean standard error of prediction (RMSEP) of 7.780N and 8.080N, and the relative standard deviation of prediction (RSD) of 26.24% and 29.71%, respectively. The global model for firmness measurement was also obtained by MLR with RMSEP of 7.740N and RSD of 26.10%, respectively. The results highlight the potential of portable Vis/NIR instruments for assessing internal quality of European pear on-site.

Abstract:60min。Using a self-made device of vacuum shelling for chestnut, the research on factors influencing the chestnut vacuum shelling performance was carried out. The results indicated that the size and shape of the chestnut had a significant effect on the vacuum shelling performance. The shelling rate increased with the increase of vacuum. The increase of the vacuum temperature and time, and the preheating chestnut under proper temperature could increase the shelling rate effectively. The optimized technology conditions of the chestnut vacuum shelling were as follows: hemispherical chestnut with the weight ranging from 7.5～10.0g per unit, pre-heating temperature 80℃ and time 40 minutes, vacuum degree 2kPa and shelling temperature 80℃ and time 60 minutes.

Abstract:The laser cutting technique was applied to chestnut shell-cutting process. The chestnut shell-cutting machine was consisted of a vibration feeder, V-shaped belt for chestnut positioning and conveying, motor drive system, laser generator, mirrors for laser reflection and focusing, control panel etc. The experiments of chestnut shell-cutting and shell puffing using laser indicated that the shell puffing rate of chestnut cut increased with increasing of the laser power or decreased with increasing of chestnut delivery speed. When the laser power is 80W and the chestnut delivery speed is 0.12m/s (means that 3 or 4 chestnuts shell could be cut per second) the shell puffing rate of chestnut cut is above 98% and its cutting quality is the best.

Abstract:To establish the extraction technology of cellulase assisted by ultrasonic wave of Momordica charantia polysaccharides (MCP), the optimization was applied to discuss some factors including ultrasound power, enzyme amount, the ratio of solid to liquid, extracting time, pH value, temperature with BoxBehnken centerunited design and the method of response surface analysis (RSM). Through establishing the second regression model, the optimal parameters were conformed as follows: ultrasound power 390W, cellulase amount 3500U/g (enzyme activity was more than 200U/mg), ratio of solid to liquid 1∶38, extracting time 40min, pH value 5, temperature 56℃. Then the yield of crude Momordica charantia polysaccharides is 21.1%, higher 7.8%, 13.5% and 7.7%, respectively, comparing with the specific heat of flooding, ultrasonic wave and cellulase. These results suggested that cellulase assisted by ultrasonic wave extraction technology was one of the effective ways to improve the yield of Momordica charantia polysaccharides. 

Abstract:10cm。An autonomous navigation system based on self-adapted fuzzy control for agricultural tractor was proposed. PLC, electro-hydraulic switch valve and proportional directional control valves were used to construct the automatic steering control system based on PD control algorithm. A self-adapted fuzzy control algorithm was proposed, GA was adopted to optimize the fuzzy rules and proportion factor of fuzzy output online. It retained the advantages of conventional fuzzy control, and meanwhile, it improved the performance of autonomous navigation control system. Simulation and field experiment indicated that the proposed navigation control algorithm could eliminate the tracking error effectively with rapid response and small overshoot, the navigation system worked stably, the maximum tracking error was less than 10cm.

Abstract:With the aim to recover the lost information of the apple harvesting robot’s vision caused by the branches and leaves, an automatic image inpainting algorithm was proposed. By calculating the so called blocked factor, the area blocked by the branches and leaves was confirmed at first. And then, a Lattice Boltzmann method based on image inpainting algorithm (LBMII) was used to recover the lost information. The examination results show that the LBMII can recover the apple image effectively, and has higher PNSR than the algorithm based on the curvature-driven diffusions. More over, the parallism of the LBMII can be used to build the high speed parallel image processing system for apple harvesting robot. 

Abstract:A binocular vision technology was used in intelligence on the targeting sprayer. Parallel axis camera captured images was used in the experiments, and through the mode of finding feature points in tree images to match the two images to solve comparability problems. Then the distance and its error between camera and the object trees were calculated. The average error was maintained within the range of 8%. Applying this method can make the intelligent pesticide target spraying so as to improve the efficiency.

Abstract:Aiming at the ambiguity and uncertainty of lesion field image border, using inference rule of fuzzy logic and self-adaptive of neural network, the self-adaptive and fuzzy neural network model was proposed to be the decisionsystem for extracting the diseased spots, and the initial values of adjusting parameters were optimized by using genetic algorithm which enhanced the speed of network training, overcame the local minimum of traditional gradient descent method. The experimental result showed that model had many advantages including accuracy, convergence, stability, robustness, and was easy to implement when implied in extracting the diseased spots of potato early blight.

Abstract:95.8%。In order to improve the accuracy and efficiency of weed identification, a method for cotton-weed recognition was proposed by using the combination technique of features optimization and least squares support vector machine (LS-SVM). After a series of image processing such as graying, filtering and threshold segmenting, six geometric shape features and seven Hu moment invariants were extracted from the single plant leaf. Then, using particle swarm optimization (PSO) algorithm, the extracted features were optimized in order to reduce the size of the training data sets. Finally, the weed was identified by using the trained classifier. The experimental results indicate that this method can effectively compact feature subset and maintain a higher accuracy than using the original feature set, the average correct identification rate is 95.8%. 

Abstract:1.1%。Aiming at the existed problem that greenhouse environment control systems can not accurately predict the next stage air temperature inside the greenhouse and provide the basis for the control system to control the temperature optimally, a temperature forecast model based on time series method was developed. The temperature series collected from Jun. 6, 2001 to Sept. 16, 2002 in a hemispherical-roof greenhouse was studied. Firstly, the greenhouse temperature series was annual and first-order differenced in order to get a stationary greenhouse temperature series. Secondly, according to the characteristics of the autocorrelation coefficient and partial correlation coefficient of the first order annual difference series of greenhouse temperature, the ARMA（p，q） model was put forward to fit the greenhouse temperature. Finally, according to the minimum principles of variance estimate and the sum of squares of errors, an ARMA (4,4) model was determined as the 1-step forecast model of greenhouse temperature in summer. The test results show that the most absolute error and relative error of the forecast temperature of the 1-step forecast model are 0.8℃ and 3.2% respectively, and that the average absolute error and relative error are 0.2℃ and 1.1% respectively.

Abstract:Aimed at the voltage-sensitive problem of EC-5 sensor which was suitable for WSN soil moisture acquisition nodes, the sources of detection error was analyzed according to the sensor working principle. It was found that the error would increase with the soil moisture when sensor parameters were determined. Using CC2430 platform as WSN information transmission node, WSN soil moisture acquisition system with multiple nodes based on controller and host computer was established. Taking node voltage u and the real soil moisture θ as parameters, the inverse modeling of nonlinear soil moisture sensor system was performed by neural network, and the compensation of EC-5 sensor detection error caused by supply voltage was implemented in host computer. Experimental results showed that this method could sharply reduce the influence caused by node voltage variation and improve the detection precision. 

Abstract:P-TDR is a new time-domain reflectometry based on the phase detection principle. It measures the travel time of testing signal by detecting phase difference of the incident and reflected waves, and thereby calculates the soil moisture content. The PTDR measurement accuracy of soil moisture content reaches the level of the traditional TDR. But if it is used to measure soil conductivity (σ) by detecting the testing signal reflectivity (ρ), verification is necessary. The measurement method of soil conductivity and the principle of P-TDR were introduced firstly. Then an experiment was arranged. The testing signal reflectivity of P-TDR was measured in 8 sandy loam soil samples, which had different salt contents under five levels of soil moisture content (θ). The relationship between ρ and σ was modeled respectively by using linear and quadratic polynomial model, and the quadratic polynomial was chose for PTDR electrical conductivity measurement model, whose determination coefficient was above 0.812. The experiment results also showed that soil moisture content had greater influence on the electrical conductivity measurement. After the analysis of the relationship between soil moisture and the quadratic polynomial coefficients, the predictive model of soil electrical conductivity, which is the function of ρ and θ, was established. The experiments of in-situ measurements are needed to research the influence of factors such as soil texture on the P-TDR soil conductivity measurement. 

Abstract:On-the-go measurement of soil parameters in field-scale, which managed in a determinate farming and fertilizing mode, was carried out using soil moisture content (MC), electrical conductivity (EC) and mechanical resistance (MR) measuring system and EM38. The correlativity among the soil parameters was investigated based on the soil parameter spatial distribution. The results showed that the combined sensor could response the field MC and EC variation. Soil EC in field scale could be predicted by soil MC, MR and fertilizing information. 

Abstract:Three deformation stages of straightening T-rail’s warpage, including elastic deformation, elastic-plastic deformation and elastic unloading springback, were analyzed according to the elastic-plastic mechanics theory, the load-stroke expressions of three deformation stages were gained through deriving relationships among load, bending moment and stroke, and then the straightening load-stroke model was established. By using the model, the straightening stroke could be calculated directly and accurately according to the initial deflection. In order to verify the model presented, taking T89/B guide rail for example, the straightening experiment was conducted. Comparing the calculation strokes by model with experimental results, the relative errors are less than 10%. It showed the presented model was practical. It will give theoretical support to the development of automatic machines for T-rail’s warpage straightening.

Abstract:A conversion method from cartesian space trajectory to joint trajectory of spray painting robot based on Dijkstra algorithm was presented to meet the requirements of offline programming spray painting robot and characteristics of spray cartesian space trajectory. Through analyzing the relations between the part coordinates and the robot basal coordinates, the spray cartesian space trajectory was converted to the robot basal coordinates by three points calibration of auxiliary feature points. An optimized model was established to obtain the shortest joint motion distance in robot inverse kinematics solutions. The distance between all of the inverse kinematics solutions was described by a directed weighted graph, and the Dijkstra algorithm was employed to obtain the optimal combination of inverse kinematics solution. Finally, the feasibility and efficiency of the method were verified by spray experiment.

Abstract:Numerical solution for the roller elastohydrodynamic lubrication (EHL) contacts with longitudinal surface roughness under fully flooded and starved conditions was obtained. The results showed that the lubricating performance in the middle and the end parts of the roller was different. Owing to the side leakage effect, the film thickness at the end parts of the roller was much lower than that in the middle part of the roller. Oscillations of the film thickness and pressure could be caused by the surface roughness. Under pure rolling condition, the wavelength of the film oscillation equaled the wavelength of the surface roughness, while the amplitude was larger than that of the roughness. Surface roughness could reduce the film thickness, especially for the starved EHL contacts. The smaller the thickness of the oil supply layer was, the easier the starvation in the roller contact could be. In addition, when the oil supply quantity is specified, larger amplitude and smaller wavelength are more harmful to the lubricating performance of the roller contacts. 

Abstract:Several photoelastic materials with different ingredient proportions of firming agent were made up. Freezing elastic ratios of materials were measured by the YE2538 programmable static strain gage. According to the elastic modular ratio of the steel-copper worm gears, suitable materials for worm gears photoelastic model were selected. The worm photoelastic model was made in the way of steel mandrel surrounded with epoxy resin tooth, and the gear was made by the method of integral cast. Worm gears photoelastic model was assembled in the reduction box, and the load was applied by a torsion bar, and stress freezing was finished in the oven. Stress-difference line distribution property of sections of worm gear was observed on the photoelasticimeter 409-Ⅰ. At last, the result of photoelastic method and the result of the finite element method (FEM) were compared. The result shows that differences of the maximum fringes value among the meshing teeth are minuteness, and secondary primary stress difference at the dedendum and the addendum of the tooth is larger than that near the pitch. In conclusion, the reliability of the photoelastic experiments of the worm gears is confirmed.

Abstract:The performance of the feed servo system has an important effect on CNC machine tools, including the tracking and position accuracy as well as the surface quality of the machined part. The nonlinear factors such as friction and backlash can induce unstable behaviors such as stick-slip and oscillation of the feed servo system. The mechanical and mathematical models containing friction and backlash were established for the motor direct-connected feed servo system with close loop controller. The effects of friction and backlash on the worktable under low feeding velocity were studied. A few of possible conditions for the stick-slip occurrence of the worktable were obtained. And some means for cancelling the stick-slip behavior of the feed servo system were presented at last. The research results provided a theoretical support for the optimum design and performance forecast of the feed servo system.

Abstract:In view of searching the ideal cone axis for error evaluation of the conicity, a new kind of algorithm of evaluating conicity error, named as mesh searching algorithm, and the mathematical model of conicity error were presented. The algorithm has three steps. Firstly, a certain length square was collocated around the centre of least square circle on the initial section and terminal section. Secondly, a series of mesh points on the initial section and terminal section could be obtained by dividing the certain length square. And a series of lines could be obtained by connecting each mesh point on the initial section to the each mesh point on terminal section. Thirdly, a series of lines were regarded as theoretical cone axis, then the minimum zone conicity error could be calculated according to the definition of conicity error. The principle of the method and the steps of using the mesh searching algorithm to solve the conicity error were described in detail. Results of the calculation example revealed that the conicity error could be evaluated effectively and accurately by using the mesh searching algorithm.

Abstract:A model of chip formation for high-speed machining was proposed. A serial of parameters were built to assess the deformation of the chip segment. Turning experiments were carried out on a kind of high-strength steel, AerMet100, to validate the model. A further discussions were made on the experimental results on which a model of chip formation at different cutting speeds was developed. The mechanisms of chip deformation at the different cutting speeds were studied qualitatively. It was found that with the increase of cutting speed, the material dynamic yield strength, tensile strength would be strengthened and the influence of thermal softening effect, strain hardening effect would be weakened, which could decidedly lead to the onset of serrated chip.