Abstract:Multi-dimensional simulation was conducted on a small high intensified diesel engine. The influence mechanism of the interaction of intake swirl and spray angle on the in-cylinder mixture distribution, fuel evaporation, mixing and heat release processes was analyzed. Optimum matching criteria was finally acquired. The results showed that increasing and decreasing the intake swirl and spray angle could accelerate the fuel evaporation rate before and after TDC respectively. Swirl could accelerate the process of mixing fuel and air, but if spray angle was too large, the mixing rate in the later part of injection could be retarded. When the swirl ratio and spray angle were matched appropriately, the mixture would be more uniform and the SMD would be smaller, which could significantly optimize the premixed combustion process.

Abstract:The flow characteristics of solenoid valve region of electronic unit pump (EUP). EUP was rebuilt by using optical visualization observation. A diaphanous glass window was designed in the pump, and the transient flow in the solenoid valve outlet was observed by a high-speed camera. By gray processing of pictures, the brightness curve within the control valve region was acquired. Results showed that cavitation occurred in control valve of EUP and formed the two phase flow phenomenon. The formation of cavitation had two factors, one was due to flow region in control valve where high-speed fuel flow within was quiet narrow, another reason was that the control valve hit the baffle which caused vibration and impingement, hence the fuel was extruded.

Abstract:Based on the law of conservation of energy, the energy model in each cycle of the free-piston generator was established. The energy conversion in one cycle was obtained and the transfer process in continuous cycles was analyzed. The rules of influence of different compress ratios on energy and performance were attained. The results showed that the brake efficiency of the free-piston generator could be 40% ideally. The loss in the combustion, scavenging and heat release was the big part of the whole. In the continuously running, much energy at the end of the power stroke in one cylinder was transferred into the other cylinder as the compress energy. It affected the next combustion. The effects with the compress ratio varying on energy conversion and brake efficiency were different. Keeping the compress energy stable was important for the operation control.

Abstract:In order to improve the particle spatial distribution, promote the mixing of oil and gas, and enhance airflow movement in a combustion chamber, a swirl chamber combustion system in direct injection diesel was investigated. The mixture formation and combustion progress in the combustion chamber were simulated, including different nozzle hole cone angles with 146°, 150° and 154°. The results showed that in view of the fuel/air equivalence ratio distribution, the uniformity of mixture on nozzle hole cone angle of 146°was better than others. The combustion swirl and anti-squish swirl have effect on temperature distribution in the combustion chamber. NO emission was lowest with nozzle hole cone angle of 154°, while soot emission was lowest with nozzle hole cone angle of 146°. The emission performance was better than others with nozzle hole cone angle of 150°.

Abstract:According to the physicochemical property complementarity of bio-ethanol, biodiesel and petroleum diesel, a multi-component fuel (BED fuel for short) with bio-ethanol, biodiesel and petroleum diesel was mixed. The compatibility and stability of the BED fuel were studied under four temperature (0℃、10℃、15℃、20℃) environments. The relation between the engine performance and emissions and the six groups of BED fuel in different proportions were studied with the experiments. The results indicated that, the engine power with BED fuel greatly reduced at high loads in intermediate speed and the reducing amplitude raised with the increasing proportion of ethanol and bio-diesel components, the drop ratio was up to 10.2% compared with diesel. The equivalent brake specific fuel consumption (EBSFC for short) was lower than that of pure diesel. The change of EBSFC with BED fuel in different proportions did not show regularity at low loads, while the EBSFC reduced with the increasing oxygen content in BED fuel, the drop ratio was up to 9.2% compared with diesel. The CO emissions decreased significantly at high-loads and the biggest ratio was up to 70.1%. The Nox emissions rose with the increasing of bio-diesel component and reduced with the increasing ethanol component, the biggest raised ratio was up to 29% at rated working conditions. The THC emissions reduced with the increasing bio-diesel component and rose with the increasing ethanol component, the biggest decreasing ratio was up to 32.6% at rated working conditions.

Abstract:With the aim to reveal the difference of combustion and heat release process in cylinder of engine fueled with soya methyl ester and petroleum diesel, high speed photography was used to catch combustion flame images in cylinder and thereafter the pressure indicator diagram was collected to compute the heat release rate. The combustion processes of biodiesel and petrolic diesel were illustrated in the crank angle coordinate with the direct flame images combined with analysis of heat release. Due to the contribution of bigger bulk modulus and higher cetane number of biodiesel, the beginning of injection for biodiesel was 0.7°CA earlier than that for diesel, and the ignition time of biodiesel occurred earlier 1.5°CA than that of diesel, under the unimproved conditions of fuel supply system. During the rapid combustion period, both the brightness and its lasting time of biodiesel were less than that of diesel. The heat released by the chemical reactions without obvious flame at the end of combustion only accounted for 2%~3% of the total cycle heat energy released by fuel.

Abstract:In order to study the effect of operating parameters on the heat release models calculation result of compressed natural gas (CNG) engine and confirm the models application conditions, Gatowski et al model, Apparent heat release model and R—W model were used to calculate heat release rate and mass fraction burned based on the cylinder pressure and crank angle data measured from a spark ignition CNG engine. The effect of engine operating parameters on the calculate results of different heat release models were discussed. The results show that the difference of heat release rate and mass fraction burned calculated between Apparent heat release model and R—W model is not obvious, which indicates that the two models can be in common use. The three models are affected slightly by ignition advance angle and excess air ratio. Difference among three models calculation results is not huge with small throttle opening. Compared with the other two models, the calculation results of Gatowski et al model are affected significantly by engine speed. The three models substitutes mutually under the condition of small throttle opening or high engine speed. Gatowski et al model is more accurate and suitable for slow engine speed compared with the other two models.

Abstract:In order to study the response characteristics of variable cam phaser (VCP) under each operating parameter, a test bench was built up, and the methods for calculating the dynamic response time of VCP were put forward. The response time of the maximal VCP advance and retard position, under operating parameter include engine speed, hydraulic oil’s pressure and temperature, can be measured. The experimental results indicate that response speed under the advance direction regulating of VCP is less than retard direction. Engine speed doesn’t have much prominent effect on VCP response speed. As the increase of oil’s temperature, the response speed become faster, but the rate of change is decreasing when the temperature higher than 70℃. The response speed augments as the oil’s pressure increases, especially in low pressure (lower than 0.4MPa).

Abstract:Small diesel engines have weak dynamic performance and emit black smoke when working overload in a short time. With the aim to solve that problem, a kind of electric temporary turbocharger was designed. The system includes a supercharger driven by DC brushless motor, power supply system on board and a switch. The system is powered by a 24V battery and does not consume too much power due to its short running time. Bench test showed that the supercharging ratio of the electric temporary turbocharger was between 1.014 and 1.020. The power of diesel engine increased by 5.0%~9.1%. The fuel consumption decreased by 8.5%~14.0%. The smoke exhaust problem was improved. Test results indicated that the electric temporary turbocharger could meet requirement when the small diesel engines were weak dynamic performance temporarily.

Abstract:Pedotransfer function was established to predict soil water retention curve by using the feed-forward neural networks methods. The prediction performance and application uncertainty of pedotransfer function were analyzed according to the error statistics index and Hydrus-1D water dynamics model. The results showed that mean absolute error value of θ1000, θ10000, θ15000（soil water retention θ1000, θ10000, θ15000 at soil water suction equal to 1000cm, 10000cm and 15000cm, respectively） using pedotransfer functions with particle size distribution, bulk density, θ60 as predictor was 42.86%,23.87% and 26.15% lower than the value of PTF1 using particle size distribution as predictor. Mean absolute error of θ100,θ10000,θ15000 using pedotransfer function which added θ15000 as predictor was 8.67%,16.96% and 15.95% lower than pedotransfer function using θ60(soil water θ60 at soil water suction equal to 60cm) as predictor. The parameters of van Genuchten equation were predicted using pedotransfer function were used to simulate soil water, the MAE value of PTF using θ60 as predictor was 11.11% lower than PTF using particle size distribution as predictor. Therefore, adding additional θ15000 cannot reduce the uncertainty of pedotransfer function application comparing with the pedotransfer function using particle size, bulk density θ60 as predictor.

Abstract:Using Yucheng county with soil salinization as a typical area of the north China plain, spatial variability of maize yields was described and influence of the terrain attributes on maize yields were discussed by space interpolation techniques based on measuring maize yields in field and extracting terrain information. The results showed that maize yields gradually increased along the northeast to southwest of the county with increasing the elevation. Although terrain undulated very slightly, the increasing trend of the elevation was agreement with the distribution of yields from low to high. A very significantly positive correlation (R=0.263, p<0.01) existed between maize yields and elevation. Meanwhile, a significantly negative correlation (R=-0.245, p<0.05) existed between maize yields and plane curvature, indicating that the bigger plane curvature, the easier saline accumulation leading to decreased maize yields. The combined effects of elevation and plane curvature explained 12.4% of the observed variability of maize yields.

Abstract:The perforated plastic mulch affects soil water movement in the heterogeneous field. Especially when soil water repellency degrees are different, the soil water movement process tends to be more complicated. Soil column evaporation experiments were conducted for Lou soil layered by sand and sand layered by Lou soil at various hydrophobic degrees under the controlled open-hole-ratio conditions. The soil water evaporation and soil moisture profiles at different conditions were measured and analyzed. The results showed that the curves of cumulative evaporation and time for full plastic mulch were obviously low, the corresponding soil moisture profile for ten days of evaporation was closed to the initial moisture profile, and this characteristic was more suitable to Lou soil layered by sand. When the open-hole-ratio increased, the cumulative evaporation of the two types of layered soil increased obviously compared with the full plastic mulch condition, showing the decreasing of mulching effects for conserving water even at small open-hole-ratios. When the water repellency degree increased, the cumulative evaporation decreased slightly, indicating the hydrophobicity of soils slowed down the water movement speed. When soil was seriously hydrophobic, hydrophobicity affected soil water movement more than open-hole-ratios. Logarithmic functions fit well for describing cumulative evaporation and time of various hydrophobic degrees of Lou soil layered by sand, while power functions and logarithmic functions were selected for sand layered by various hydrophobic degrees of Lou soils.

Abstract:Characteristics and dynamic changes of soil water infiltration under different soil bulk density and different stabilizer content were analyzed by one-dimensional vertical infiltration experiments. The results showed that soil bulk density had significant influences on infiltration capacity of stabilized soil from 1.2～1.4g/cm3 of soil bulk density ranged. The influences of soil bulk density on infiltration rate were stable and constituent. With increasing soil bulk density, cumulative infiltration decreased. Stabilizer amendment amount had effects on cumulative infiltration and wetting front under the same soil bulk density. Cumulative infiltration were the highest at 0.05%～0.1% amendment amount of EN—1 stabilizer, and were higher the control. There was good linear relationship between the amount of cumulative infiltration and the wetting front distance. With increasing amendment amount of EN—1 stabilizer, cumulative infiltration and wetting front had trend of increase first and decrease then. Fitting the relationship between infiltration rate and time with Philip model, Kostiakov empirical formula and index formula, the results showed Kostiakov formula was more accurate than other models and fitted values of its had the best results at higher soil bulk density.

Abstract:The soil with application of water retention agent was taken as an object to establish a model of porosity change, and the parameters of the model were calculated and verified by measuring the porosity of the soil under different moisture conditions. The model was found to have better simulation effects. On this basis, water-swelling property and porosity change of the soil with application of water retention agent were analyzed. The results show that the more water retention agent is applied, the more the soil swells and the more the porosity increases.

Abstract:The experiment was conducted to study the effects of regulated deficit irrigation on these parameters of the Korla fragrant pear tree.The water deficit applied before the fruit enlargement stage included: slight water deficit, the trees were irrigated with 60% of US Class A pan evaporation (Ep); severe water deficit, the trees were irrigated with 40% of Ep. During the fruit enlargement stage, both water deficit treatments were irrigated with 80% of Ep. The control was irrigated with 80% of Ep during the whole growth season. The results indicated that the leaf photosynthesis rate, transpiration rate and stomatal conductance were significantly reduced by the soil water deficit. After full irrigation resumed, the leaf photosynthesis rate, transpiration rate and stomatal conductance restored rapidly to some extent, the physiological parameters of slight water deficit reached the control level in the middle August, however, those of the severe water deficit were always lower than the control. As compared with the photosynthesis, the transpiration was more sensitive to the soil water deficit, resulting in the improvement of the leaf water use efficiency.

Abstract:The experimental area located in Mizhi experimental station in loess plateau of China. According to the meteorological data observed by automatic weather station of Mizhi experimental station and using FAO Penman—Montieth equation, the crop reference evapotranspiration was calculated consequently in jujube’s growth period. Additionally, combined with crop evapotranspiration of jujubes under sufficient irrigation, the crop coefficient of drip-irrigation jujubes was studied. The water requirements and crop coefficient was determined in each growing period of jujube. Water requirements (crop evapotranspiration) in sprout-leaf development period, flowering and fruit-setting period, fruit development period and fruit development period was 68.1mm, 117.4mm, 224.4mm and 66.2mm, respectively. Crop coefficient in each growth period was as follows: 0.496 in sprout-leaf development period, 0.681 in flowering and fruit-setting period, 1.262 in fruit development period，and 0.944 in fruit mature period. A function relationship was established between crop coefficient and leaf area index, and the results demonstrated that there was a quadratic curve relationship between crop coefficient and leaf area index.

Abstract:Based on indoor and field experiments, velocity distribution properties of U-shaped open channel were analyzed. Exponent formula for horizontal velocity distribution properties and two-power law for vertical velocity distribution properties were established. The methods to define the parameters were given. Then the midline three-point for flow measurement of open channel was put forward based on the velocity distribution properties of U-shaped channel. The fractional errors of flow velocities calculated by the midline three-point method in indoor experiment under different operating conditions and field experiment were within ±4% and ±5%, respectively. Validations showed that the midline three-point method increased the computational accuracy of flow measurement in open channel. In addition, the workload of the flow measurement by the midline three-point method was substantially reduced by more than 60% compared with velocity-section method which needed nine measuring points.

Abstract:Aimed to the problem of measurement error influence of soil profile moisture sensor caused by variation of soil physical and chemical properties, the soil profile moisture sensor was firstly designed based on high frequency capacitor. And then the analysis was made through the experiments of sensor output voltage influenced by variation of soil physical and chemical properties such as soil temperature, electrical conductivity and bulk density. Thirdly, the soil moisture correction model based on the influence of temperature was established through statistics regression processing method. The performance of sensor was tested at last. The experiment results showed that the sensor output voltage linearly increased with soil temperature changes ranged from 5℃ to 45℃, and it decreased with electrical conductivity increasing when the electrical conductivity was greater than 2mS/cm. Moreover, the sensor output voltage showed a decreasing trend with bulk density increasing. The largest measuring absolute error was 4.70%, root-mean-square error was 0.02524 and correlation coefficient R2 was 0.9679 through comparing the measuring value between sensor and traditional drying method at normal temperature.

Abstract:High-accuracy measuring system of soil temperatures was designed. Thermocouple was used as temperature sensors. Under the control of the micro-controller, high-accuracy and automatic detection was achieved to analyze the impact of soil temperature on water and heat of soil. The system was studied from three aspects, such as hardware circuit, software and curve fitting. By using the electric bridge method for temperature acquisition, least squares method was used to piecewise fit samples values and temperature. Their relationship curve was described. The measurement error was compensated and corrected to ensure the measurement precision. The result showed that the experimental absolute error was less than 0.02℃.

Abstract:The drainage pressure difference of self-cleaning screen filter was calculated, and the total value of pressure difference for 80 mesh and 120 mesh was also calculated respectively at first. Contrasting with measured value, the result indicated that the calculated value and measured value were substantial identical. Then, the law of pressure difference was analyzed particularly, which influenced by restriction condition as flow, sand and time, etc. Finally, the variation curve of clean and muddy head loss acquired by the experiments, under the condition that the head loss could not ascend sharply, the best drainage pressure difference for two kinds of mesh was put forward, which could provide reference for the pressure difference calculation of screen filter.

Abstract:Motion of tracer particles in the centrifugal pump was calculated by discrete phase model. In this model, the fluid field of the centrifugal pump was solved by the two-equation RNG k—ε turbulence model. The pump performance curves were simulated to check the calculation accuracy by comparing with the experimental performance curves. Based on the result of the flow field, the tracks of tracer particles with different densities and diameters in various conditions were achieved by using Lagrange method. Through comparing particle trajectory with fluid streamline and analyzing the particle speed changed in the relationship with the spatial scale, the particles tracking characteristics were studied. Numerical simulation results showed that tracking characteristics of different densities, particles were significantly different when their diameters were greater than 50μm. While diameters were less than 20μm, densities were very low impact on the following performance. It was very important when the particle density was equal to the density of fluid. In the channel with unstable flow such as the vortex flow, the particle trajectory line was closed to the fluid flow line when the tracer particle with smaller diameters and the density was the same with the fluid density. Changing with spatial scale, the particle’s speed was closed to the fluid velocity when the particle’s diameter was under 20μm. Finally, taking the particle scattering characteristics into account, it was recommended that 20μm polystyrene should be chosen as tracer particles for this centrifugal pump.

Abstract:According to the formula of the ratio K of the maximal axle power to the rated axle power of the non-overload centrifugal pumps, K was expressed as the function of specific speed, impeller outlet angle and number of blades by calculating the formula. The three-dimensional image of K and contours about specific speed and impeller outlet angle of K under different numbers of blades were drawn based on the function. K is not close to the number of blades; while the impeller outlet angle and specific speed have a greater effect on K . Under the same K , the higher the specific speed was, the bigger the impeller outlet angle would be. Reasonable impeller outlet angle can be chosen according to the specific speed and K from the contours. The example showed that the method can make the design of non-overload centrifugal pumps successfully and quickly, and can avoid the blindness in choosing the impeller outlet angle with the traditional method.

Abstract:The advantages and disadvantages of several commonly turbulence model in centrifugal pump inner flow simulation were analyzed. Two new models based on SST k—ω turbulence model were improved with considering the effects of rotation and curvature. The procedures of new models were implemented on the open source code OpenFOAM. Simultaneously, the new turbulence models were adopted to simulate the inner flow in a centrifugal pump with different specific speeds under different operating points. Lastly, comparisons were made with experimental results and the numerical results from the original and modified models. The results showed that the modified models could calculate the inner flow of centrifugal pump successfully, and energy performance by new models was closer to experimental results than that of original model.

Abstract:The guide vanes were designed by using the axial flow pumps isolated blade design method based on Gottingen airfoil blade. The experimental studies on the basic rule and the regulatory mechanisms of prewhirl regulation for the centrifugal pump were made. Comparison experiment tests showed that the inlet guide vane installed with long-string side close to the center axis on the improvement of the external characteristics of centrifugal pump was better than the other. Also the inlet guide vane installed with long-string side close to the center axis has enlarged the high efficiency scope and improved the hydraulic performance of the centrifugal pump. When compared with the performance of the centrifugal pump without inlet guide vane, the peak value of efficiency was enhanced by 2.3% after the guide vane was installed. This method improved efficiency and saved energy for the centrifugal pump.

Abstract:According to the different movement characters of screw segment and centrifugal segment of liquid-solid two-phase flow in the screw centrifugal impeller and the structure characters of screw centrifugal pump impeller, the vane profile parameter equation group for variable-dip screw centrifugal pump was derived. The meridian velocity distribution can be changed though changing some parameters of the vane profile parameter equation group. Thus the better meridian velocity distribution could be found by using this method. Using the parameter equation group, the CAD and numerical simulation of 3-D flow field were also facilitated for screw centrifugal pump.

Abstract:The recirculation flow exists at the inlet of the impeller when the axial-flow pumps operate at the low flow rate. At this condition, the pump efficiency falls down and the pump system vibrates seriously, sometimes leads to structural damage, so the pump should avoid operating at this unstable condition. Five schemes with different baffles at the inlet of axial-flow pump impeller were presented. 3-D incompressible flow fields, for different baffle schemes, were simulated by using the commercial software ANSYS CFX. The computed results showed that the distance between the baffles and the impeller was the key factor that influences the performance of axial-flow pumps at the condition of low flow rate. Among these five schemes, scheme No.3 was the preferred plan. The flow field at the meridional plane shows that baffles could reduce the backflow at the inlet of axial-flow pump, reduce the pressure at the suction side and increase the lift of the blade, so as to increase the efficiency of axial-flow pumps at the condition of low flow rate.

Abstract:Combined with the characteristics of multi-stage submersible pump, the pump with sloping impeller and space guide vane was optimized using efficiency as optimization object. To improve the accuracy of numerical simulation, parametric fitting for sloping impeller and space guide vane was carried out. In the process of optimization, the blade inlet and outlet angle of the impeller and guide vane were considered as the control parameters. The range of angle was increased ±20°compared with the original model. Based on the successive flow field check, the optimal impeller model was obtained in the variation range of control parameters searching the optimum value of objective function based on genetic algorithm. The optimal model was obtained when inlet angle at the bottom of the blade was 35.53° and the outlet angle was 27.32°, the inlet angle of the guide vane was 15.48° and outlet angle was 61.75°. The pump efficiency increased by 4.12%, and the single stage head increased 1.449m. The range of high efficiency has been extended, the stability of pump operation is improved, and the performance of the pump is optimized.

Abstract:Co-pretreatment of wheat straw by urea and microorganism was conducted. The effects of supplement dose of microorganism in biological pretreatment of wheat straw on its anaerobic digestion for biogas production were investigated by using a self-made anaerobic digestion device with pretreated wheat straw as raw materials. Results showed that the total yield of biogas reached the maximum of 7968mL, which was 23.11% higher than the control, when the urea concentration, pH value of biological pretreatment and ratio of Phanerochaete chrysosporium to Trichoderma reesei added into the wheat straw were 35g/L, 4, and 1∶1, respectively. The values of VFA, CH4 and pH value were located in normal range. The maximum CH4 content was 51.33%, which was 6.01% higher than that of control. The fermentation time was shortened to 23d during the whole experiment.

Abstract:Under mesophilic temperature (35℃), the component changes of rice straw before and after anaerobic fermentation were compared. Results show that gas production of amination pretreatment straw is the largest, and VS gas production is 356.80mL/g, 11.70% higher than the control group; the maximum of methane is achieved 70% above, which shows no significant difference between each group. Lignocellulose content presented down trend after anaerobic fermentation, and degradation rate is proportional to the gas production. Compared with the original rice straw, cellulose, hemicellulose and lignin degradation rates of amination pretreatment straw are 28.49%, 51.73% and 7.13% respectively.

Abstract:Refer to the shortage of current recall model which can only optimize recalled size, the batch dispersion model was analyzed. The quality property was added to the bath dispersion model. The constraint condition based on the size proportion and quality weight of raw material-component-finished product was given. The joint optimization model of recalled size and product quality was proposed. The computing consumption was discussed. Results of algorithm analysis and optimization examples showed that the model could reduce the recalled size on the basis of improved quality of the finished product.

Abstract:Calibration model for firmness of Agaricus bisporus during storage was developed based on near-infrared (NIR) diffuse reflectance spectroscopy quantitative analysis techniques. Partial least squares (PLS) regression was carried out to analyze the spectroscopy. Four different spectral pretreatment methods (first derivative, second derivative, SNV, SMC) were used to compare calibration results for firmness. The result showed that the best calibration models，in the selected wavelength range of 5000~10000cm-1，could be obtained by the second derivative spectrum with the determination coefficient of calibration of 0.9471, and the determination coefficient of prediction of 0.8261. The results indicated that the detection method based on near-infrared diffuse reflectance spectroscopy was simple, and could be used for non-destructively evaluating the changes of firmness in Agaricus bisporus during storage in time.

Abstract:Using flat sweeping frequency ultrasonic technology, degradation of dimethoate in aqueous solution under ultrasonic field at different ultrasonic frequencies, fixed/sweeping modes, radiate solution volumes, radiate time were investigated. Radical mechanism under ultrasonic field was studied. The results showed that degradation efficiency at sweeping frequency ultrasound mode was proved to be superior to that at fixed mode, and the efficiency of double ultrasonic plats was better than the simple plat. The better treatment system of ultrasonic degradation operating parameters were frequency 68kHz, power 80W (corresponding to the processing volume of 8L), sweeping period 100ms, frequency combination of 68kHz with 68kHz, radiate time 180min. Under these conditions, the degradation rate of dimethoate with initial concentration 3mg/L reached 71%. Mechanism study results indicated that the degradation of dimethoate in aqueous solution by ultrasonic was partly caused by free radical oxidation.

Abstract:The physical and chemical indexes of the squeezing white sesame oil from different areas were determined, including the refraction index, saponification number and unsaponifiable matter content, etc. The fatty acid compositions of white sesame oil were analyzed by using gas chromatography. The relatively content of unsaturated fatty acids was more than 84%. The method of pancreatic enzyme selective hydrolysis was used to analyze the triacylglycerols molecular structures in the squeezing white sesame oils. The LOL (sn-2-oleic acid-1,3-two linoleic acid glyceride) relatively content was the highest (22.98%～25.62%). The vitamin E and sesamin contents of the sesame oil were 13.73～54.43mg/(100g) and 60.14～69.10mg/(100g) respectively which were analyzed by using HPLC. The oxidative stability of the squeezing white sesame oil of different areas were measured. The results showed that the oxidative stability of white sesame oil (No.4) was relatively good.

Abstract:Effects of the air velocity in heat exchanging pipes on heat exchanging and water vapor transformation was studied in double-film covering greenhouse during heating at night in winter. The temperature and humidity in inlet and outlet of heat exchanging pipes, floor temperature in heat storage greenhouse and outside temperature were measured at different air velocities in the heat exchanging pipes. The humidity ratio, enthalpy of inlet and outlet of heat exchanging pipes and the power for heating were computed. The results showed that the temperature and enthalpy of cold air with high humidity flowing through heat exchanging pipes increased apparently and the humidity reduced when the air velocities in heat exchanging pipes were respectively 0.6m/s, 1.0m/s, 1.5m/s, 2.0m/s, 2.5m/s and 2.8m/s during heating at night after heat saving in clear days. The power for heating was enhanced with the increase of the air velocity in heat exchanging pipes. The average power for heating is 1.0kW, 1.6kW, 3.2kW, 6.4kW, 7.2kW and 7.7kW respectively. The heating effects is not distinct when the air velocity in heat exchanging pipes is less than 2m/s, while the continuity for heating is poor when the air velocity in heat exchanging pipes is higher than 2.5m/s. Therefore the rational air velocity in heat exchanging pipes is 2.0m/s for heating at night when the temperature satisfies the growing requirements of the crops.

Abstract:Multi-span plastic greenhouses mainly depend on solar heat storage. In winter, greenhouse is closed for prolonged periods for thermal insulation to avoid indoor heat being lost. Therefore, this would lead to indoor high humidity and consequently the occurrence of crop diseases. For making a good compromise between dehumidification effectiveness and indoor heat loss prevention, a full-scale computational fluid dynamics (CFD) model was developed based on an 11-span plastic greenhouse. Firstly, the model was validated by comparing experimental humidity with CFD simulations under roof ventilation. CFD simulations had similar trends to those of the experiments, with less than 5% difference. Then, the validated model was used to investigate the influences of vent configurations (i.e. side, roof and side plus roof) on the airflow pattern and humidity field inside the greenhouse. Simulations showed that roof ventilation tended to be the best. With the roof ventilation, dehumidification in the crop canopy could be achieved in 3 min. After dehumidification, relative humidity was reduced from 92% to 68% and indoor humidity homogeneity was good. Moreover, responding heat loss was less. Therefore, this ventilation mode is able to meet the requirements of thermal insulation and dehumidification under winter climate conditions.

Abstract:A wireless intelligent image sensor node was designed. The hardware processing platform combined chip CC2430 and LPC1766. Image frame, which was collected by the serial camera, was divided into many packets which were transmitted through ZigBee protocol one by one. The experiment results showed that the node’s maximum communication distance was 160m, and the node packet loss rate was low. In addition, the JPEG format image acquired by camera was about 10kB which takes 135s to transmit via ZigBee. The designed node, with compact structure, stability work condition and low power consumption, could realize acquisition and transmission of the greenhouse environment information. So, it can meet the need of the greenhouse environment monitoring.

Abstract:According to locust’s response characteristic stimulated by light, sound and vibration, the experiment of locust’s phototactic response stimulated by light-sound-vibration coupling effect was carried out by using the designed experimental equipment. The results showed that light sound vibration coupling stimulated locust’s phototactic effect. The stimulation effect of its pull-push and drive could realize locust’s phototactic induction effectively. The illumination of combined spectrum decided locust’s phototactic aggregation. The illumination increased by 10 times, the effect of locust’s phototactic aggregation stimulated by light-sound-vibration coupling increased by 25%. Within a certain range, light-sound-vibration stimulated locust’s phototactic direction response effectively. The regulative spectrum illumination leaded to locust’s phototactic response. Vibration decided the driving stimulation of locust’s phototactic response. The audio frequency played the important role in gain motivation. Light-sound-vibration signal stimulated locust’s multiple receptors and generated the superimposition effect contributing to locust’s phototactic aggregation, so locust’s phototactic induction effect could be enhanced effectively through combining different audio frequency mode, regulatory mode of spectral illumination and circulating vibration mode.

Abstract:A modified Freeman chain code algorithm to determine the number of overlapped regions in citrus binary images was proposed. Three components, including S, 8, and 9, were inserted in the original Freeman code. During the identification process, the improved chain code was first obtained. Then the appeared times of code “8” was computed. The number of fruits in the overlapped regions can be obtained according to the outline of the fruits. The improved chain code algorithm was applied to evaluate the citrus images. The experimental results showed that the proposed algorithm was effective in identifying the overlapped fruits when the number of overlapped regions was between 2 and 3 where it achieved accuracy of 100%.

Abstract:With the demanding of morphological features recognition in picking robot machine-vision system, preference artificial immune net (aiNet) was used as the image recognition algorithm, mainly modified the structure of the algorithm to promote the accuracy rate. The algorithm was modified according to picking environment and real-time require. The simulation proved the clustering accuracy of preference aiNet reached to 81.67% in the sunny day and 87.69% in the cloudy day. The modified algorithm has certain meaning in the next research of picking robot.

Abstract:In order to overcome the limitation of image segmentation methods based on 2-D histogram and modality in threshold techniques, a method based on the combination of the histogram concavity and the sum of the neighborhood differences was proposed. In addition, the comparative experiment was done when the proposed method and 2-D histogram methods were applied in segmentation on X-ray images of chestnuts, apples and kiwifruits. The results showed that the image segmentation error of the proposed method was less than 2.1%, and its biggest segmentation error was only 23.7% of that of 2-D histogram method. The proposed method could get the fruits’images more precisely.

Abstract:The application system of real-time image recognition and variable spraying was designed based on the virtual image real-time controller CVS—1456. The original images, which contained pea seedlings, soil background, weed of cephalanoplos segetum, etc, were collected in normal sunlight. The color models of original images were analyzed and real-time weed recognition was realized based on R—B color features by using LabVIEW software and IMAQ Vision toolbox. The Canny algorithm was employed to detect weed edges, and three characteristic parameters of target weed, namely area, density, centroidal position, were extracted to provide positioning evidences for variable spraying. The random tests verified the accuracy and reliability of the purposed cephalanoplos segetum recognition method from complex background images based on R—B color features, in which the average right recognition rate was 83.5%, mean square deviation 0.066.

Abstract:Based on the technology of personal computer and wireless transmission, a kind of self-propelled precise feeding machine control system for single dairy cow was designed．This kind of control system can realize the precise feeding of single dairy cow based on their physiological characteristics by using the technology of RFID and MCU．Using this system, the intelligent identification for single dairy cow and the information transmitted from personal computer to MCU by air were realized. The dual-mode moving and accurate feeding was achieved. The experimental results showed that the best rate of the precise feeding machine was 0.6m/s. The response time of the machine was 0.4s. The control system can identify 96% of the single dairy cow correctly. The feeding error was controlled at below 2%.

Abstract:To meet the needs of modern agricultural machinery management, an agricultural machinery trace monitoring system based on the technology of GPS, GPRS and Google Maps was developed in order to realize the real-time monitoring and scheduling of farm machinery. This system with built-in GPS and GPRS modules, which use wireless network transfer GPS data to remote machine by single-chip microcomputer. With Google Maps API, a Web GIS system was established. An agricultural machinery management by ASP.NET was achieved. Web Service and Ajax technology was used to do such things like trace playback, length measuring, and calculation of land area function.

Abstract:In the discrete manufacturing environment of a job-shop, an optimization method for the resource configuration adjustment in order to minimize its manufacturing and tardiness cost was presented. With the material flow and work flow of a job-shop, a manufacturing process simulation model was first constructed to evaluate the performance of each resource configuration adjustment properly. Then by combining the production simulation method and improved simulated annealing algorithm, a solution algorithm for adjusting the resource amount of work centers and the production routings of products (or the configuration structure and usage way of resources) jointly was designed. In the proposed algorithm, the search and selection of neighbor configuration alternatives was guided by the critical production path analysis, and its convergence rate was then accelerated. It can gain better solution quality and efficiency than the traditional random search method, thus is more suitable for modeling and solving the large-scale resource configuration problem.

Abstract:In order to study the cavitation characteristics of a water hydraulic axial piston pump, cavitating flow in the pump was simulated based on Schnerr—Sauer model. The fluctuations of flow and pressure at the outlet of the pump were analyzed at different inlet pressure conditions. From the simulation results, it is concluded that obvious cavitations occur in the cylinder chambers which are in suction process. Cavitation regions are mainly located in the sides near to the rotation center, and more serious cavitations occur in the piston chamber which contact with the suction side of the portplate. Dynamic pulsation of flow rate and pressure at the outlet of pump are more severe when serious cavitations occur. Cavitations can be reduced if the pressure at the inlet of pump is increased, but excessive pressure at the inlet can induce pressure pulse in piston chamber which in suction region. When cavitations are decreased to some degree, dynamic pulsation of flow rate and pressure of pump can not be impacted obviously by the pressure at the inlet.

Abstract:In order to study nanoscale contact mechanics behavior, taking the rigid hemispherical surface contacted on and pressed in the silicon surface as the research object, the molecular dynamics model of nanoscale contact process was established. State changing of microscopic contact area and variation law of contact force was acquired. Results showed that the adhesion force caused the hemispherical surface and monocrystalline silicon surface to jump-to-contact when the hemispherical surface has not fully contact with monocrystalline silicon substrate surface. With the increase of contact depth, dislocations and sliding of matrix atoms appeared successively. The initial stage of contact was mainly elastic deformation with some dislocations. The later stage of contact was plastic deformation with lots of dislocation accumulation. In the process of disengagement, the substrate material generated some extent elastic recovery. When the hemispherical surface and the matrix surface were completely out of touch, the contact surface still contacted with some matrix atoms due to adhesion phenomenon. Finally, atomic force microscopy was used to finish comparative analysis of the experiment according to the parameter conditions and the contact process of molecular dynamics. The experimental results showed that molecular dynamics simulation was practicable and effective for analysis of the nanoscale contact mechanics behavior. Moreover, molecular dynamics simulation could acquire the microscopic details that not be observed through the experiment.

Abstract:A new method for evaluating the axial stiffness of ball screw at support point was proposed. Based on principle of initial parameter method, the initial parameter matrix equation was established for force and displacement of ball screw. The structural characters, including boundary condition, force balance and displacement compatibility at support point, were used to achieve initial parameter values. As a result, axial force and displacement of every point on ball screw could be obtained. The identification models of axial stiffness were built by analyzing the amplitude changes of ball screw under some load affection employing the knowledge of mechanical vibration and material mechanics. The research results are in good agreement with the results obtained by the available experiments.

Abstract:Stress concentration theory was introduced into study of grinding, and the stress concentration phenomenon in grinding process was analyzed. A single-grit model of grinding force was established based on stress concentration theory. The influence mechanism of grit-wear-area rate on cutting force was clarified with the model. Functions between grinding force and grit-wear-area rate was established. The functions showed the quadratic function relationship between grinding force and grit-wear-area rate, and the increase of the cumulative residual-grinding-thickness results in the rapid increase of normal grinding force. Furthermore, by taking the feature of the grinding wheel in use into consideration, functions of grinding force for multi-grit grinding wheel was established. The validity of the model was verified by the experimental data.