Abstract:A diesel engine exhaust heat recovery system was designed based on organic rankine cycle. Using the thermodynamics model the performance of the system was predicted, and then a diesel engine with and without the exhaust heat recovery system was experimented to validate the performance of the model. The ORC net output power and thermal efficiency were estimated under variable conditions or different working fluid mass flow rates by using the model. The results showed that the net output increased with increasing engine speed. The maximum thermal efficiencies were the same as 12.1% at the different engine speeds, and the best working fluid mass flow rates range for the exhaust heat recovery system was obtained.

Abstract:The combustion pressure characteristics of a turbocharged common rail diesel engine were experimentally investigated when using diesel/methanol compound combustion mode (DMCC). The combustion pressure characteristics were compared with the baseline engine, which including the related parameters such as the combustion pressure, the rate of pressure rise, maximum combustion pressure and combustion heat release rate. The results showed that, compared with the baseline engine, the form of heat release rate was changed significantly with DMCC mode, and the ignition point was simultaneously delayed a lot. Besides, the proportion of premixed combustion increased, and the proportion of diffusion combustion decreased. The results provided the theoretical basis for improving the efficiency and reducing the exhaust emissions of diesel engine by the DMCC mode.

Abstract:An experiment of pyrolysis process of diesel/methanol (M0/5/15) combustion particulate in oxygen was conducted by using the thermogravimetry/difference synchronization analyzer. According to the experiment data, the pyrolysis process, ignition point temperature and burnout characteristic index were calculated. The results showed that the volatile components of diesel/methanol combustion particulate were decreased and the quality of the fixed carbon particles were increased. The peak of pyrolysis rate in the first temperature interval was decreased and increased in the second temperature interval. The activation energy of the particles was reduced, and the pyrolysis performance was enhanced. The ignition point temperature was reduced, and the burning characteristic index and burnout characteristic index were increased. The combustion efficiency of particles were improved with the increase of methanol mixing proportion.

Abstract:Considering high efficient searching ability of PSO and local searching capability of SA, a hybrid PSO algorithm for solving the problem of machining processes balancing was proposed. Aiming at the characteristics of operations order and clamping constraints, an improved way of encoding and decoding was presented, which makes the coding sequence of discrete matches with the iterative evolution of continuous particle position and speed, at the same time, a method of dealing with such operational constraints was also stated, which makes the updated particles always satisfy the constraints, the convergence rate of the algorithm was improved greatly. Finally, a case of diesel engine cylinder block machining production line was illustrated to prove the validity of the proposed method.

Abstract:A six-legged parallel suspension system for tractor cab vibration reduction was designed. Aimed to the problems to determine the physical and geometrical parameters of the tractor cab hexapod parallel suspension system, the 6-DOF dynamic model was established based on the Lagrange Equation. Taken the natural frequency of the suspension system, and the damping and decoupling degrees of cab in six direction as optimize target, multi-objective optimization model was established and the sensitivity method was used in the system optimal design research. Compared with the traditional rubber liner suspension system of tractor cab, the results proved that it had good damping effect, and provided a theoretical basis for parameter selection for passive vibration control and the manufacturing of suspension system prototype.

Abstract:According to the structural characteristics of heavy articulated wheel tractor,a steer-by-wire system of the tractor was set up, consisted of electrical control system, angular displacement sensors, mechanical system and hydraulic steering system. The equivalent mathematical model of hydraulic steering system of the tractor was set up with nonlinear state space method by 12 parameters. Controlled by fuzzy self-tuning PID system, the articulated tractor simulation programs consisted of multi-body dynamics system and hydraulic system were developed, with help of Matlab software. The in-situ steering simulations of the tractor with the steering by wire system were carried out. Experiments on rigid road were carried out, and the results showed that the steering by wire system was suitable to the tractor operation condition when the speed was less than 13 km/h.

Abstract:The mathematical models of the steering, suspension and tires were established, and based on those models, the relationship between yaw velocity and heeling angle was deduced theoretically. In addition, the influence of road surface adhesion and speed on angle input was analyzed. At the same time, the change of yaw velocity and heeling angle were recorded under the different speeds and front wheel corners. Through detailed analysis the change rule of the steady state value was summarized. At last, the result of simulation and experiment showed the correctness of the simulation and the models, and provided a theoretical reference for the lateral and vertical dynamics integrated control. The proposed research ensures the driving safety, enhances the handling stability, and improves the ride comfort.

Abstract:A method is proposed based on CFD to calculate axial force of hydrodynamic coupling. By using the numerical solutions of hydrodynamic coupling inner flow field, which is unsteady, incompressible and viscous two-phase flow, the axial force is calculated. The flow field in working chamber of variable speed hydrodynamic coupling is analyzed in different filling rates under breaking condition, traction condition and rated condition, and the variation low of axial force is obtained. Axial force is measured by experiments in variable speed of high-power hydrodynamic coupling. The comparison of the calculating results with the experimental ones shows that the mean error is 8%, and the calculation method based on CFD is feasible.

Abstract:基于所研制的单活塞式液压自由活塞柴油机原理样机，对缸内气体流动规律进行了数值仿真。研究结果表明，缸内气流运动规律受活塞运动规律的影响，与传统内燃机相比，HFPDE缸内气流运动规律如下：压缩冲程初始阶段，由于活塞运动速度较小，缸内平均气体速度较小；压缩冲程后期，活塞在上止点附近运动速度增大，缸内气体加速径向流出燃烧室，平均径向速度增大，挤流效果增强；膨胀冲程早期，活塞较大的运动速度使得平均径向速度大幅增大，逆挤流效果也明显增强；上止点附近挤流和逆挤流受活塞瞬时速度影响，随着相同活塞位置所对应的活塞运动速度的增大，平均径向速度增大，挤流和逆挤流效果增强。

Abstract:The method that agricultural mobile robot acquire the navigation strategies through autonomous learning was development based on reinforcement learning and fuzzy logic. Firstly, the machine vision was applied to detect obstacles in the navigation environment, and the corresponding direction and distance between the robot and the obstacle was calculated. Then the algorithm of acquiring the more optimal navigation strategies was introduced with the reinforcement learning, so the capability of the mobile robot of adapting the dynamic navigation environment was improved. Finally, the continuous values of the direction and the distance between the obstacles and the mobile robot were discretized with the fuzzy logic rules, and the discrete navigation environment states were obtained, then the Q value table was designed for the reinforcement learning. The experiment was carried out with the wheeled mobile robot, and the experimental results showed that the mobile robot was able to automatically acquire more optimal navigation strategies in the actual environment, and fulfill the expected navigation tasks.

Abstract:An agricultural machine path tracking method irrelevant to travel speeds, aiming at the path tracking control problem in autonomous operations of intelligent agricultural machines, was presented. The method was robust to changes in travel speeds of agricultural machines. Firstly, the space parameter driven nonlinear relative kinematics model between the agricultural machine and the tracked path was deduced and the rationality and feasibility of designing control method based on the model was proved. Secondly, the paper dealt with the model by input state linearization and utilized the optimal control method to stabilize the linear model obtained by feedback linearization, and an agricultural machine path tracking control law irrelevant to travel speeds was then obtained. Finally, path tracking experiments of an agricultural machine were carried out. The experimental results showed that the precision of straight path tracking and curve path tracking were 4cm and 7cm respectively and not affected by changes in travel speeds. Therefore the effectiveness and robustness of the proposed method were verified.

Abstract:Envelop grasping model based on 3-DOF fingers driven by a flexible pneumatic actuatordirectly was proposed. Based on the principle of equalization, the interaction forces between the object and knuckle was optimized. The static model of the pressured air in FPAs and the positive pressure on knuckle or correlative friction force was built. The measure model about the positive pressure and its position, based on leverage principle depending on two touch-force sensors, was obtained. Using a series dual loops control method and the compensator about friction force, the positive pressure could be controlled precisely. In order to filtrate the high-frequency noise, the feedback signal of the pressured air in FPA was processed by different analysis. The experimental results showed that dynamic response time of the positive pressure was about 1s and the steady-state deviation was less than ±0.5N.

Abstract:Light changing and targets overlapped each other were main reasons of affecting fruit recognition accuracy under natural condition. In order to reduce both effects, a kind of fruit recognition algorithm based on multi source images fusion was studied. On the basis of image registration, H component image and amplitude image were selected as source images for fusion. The use of fuzzy logic in pixel level fusion was related to the weighted averaging approach where the weights were determined by using the fuzzy inference system (membership function and fuzzy rules). According to the law of fruit area distribution in the fused image, an head threshold detection algorithm based on histogram was presented，so as to get the best fruit segmentation results. According to statisitical properties of range image, a solution for overlapped fruits recognition using layer segmentation algorithm was designed. The experimental results showed that information on multi-source image fusion was used for fruit recognition and location more accurately and robustly than single image, overlapped fruit recognition rate was from 83.67% to 94.22%.

Abstract:Vegetable mechanized harvesting technology has attracted much more attention in recent years in China. The features of vegetable harvesters were analyzed. In the sort of leaf vegetable, root vegetable and fruit vegetable, the research progress and development of cabbage harvester, carrot harvester and tomato harvester etc in domestic and overseas were reviewed respectively. In consideration of the development and the extension, some problems in vegetable harvesters were analyzed. The main research fields were presented, including the analysis of vegetable mechanical properties, the combination of agronomy and machinery, the optimization design of mechanical structure, the improvement of harvester generality and the intelligent system of machinery-electric- hydraulic admixture.

Abstract:In order to investigate the relation between the seeding performance of precision spade punch planter of maize and the vibration caused by the simple harmonic excitation of field roughness, a mathematic vibration model between steady state responses of precision spade punch planter of maize and real seed displacement was established. The mathematic model gave the conclusion that the uniformity of sowing seed of planter was mainly decided by next factors, such as structure properties of planter, work velocity of planter, distance between the seed metering device of planter and the surface of till soil, surface conditions, and the adhere of till soil. The comparasion results between theoretical seed distance and experimental seed distance indicated the distributed trend between both distances above. It was proved that the mathematic model could be used to predict and analyze the uniformity of sowing seed.

Abstract:The structure and working principle of a magnetic plate precision seed-metering device were introduced. In order to understand the seed-filling performance, the single-row permanent magnet metering elements were made as the research object and the simulation model was established by using particle discrete element method. The seed box moving speed, the magnetic suction surface magnetic field intensity, and the effect of filling position angle on seed-filling performance were simulated, and the best combination of all factors was obtained. The simulation results showed that the main factor influence filling properties was the surface magnetic field intensity of permanent magnet, and the second was the seed box moving speed. Both prototype test and simulation test showed that the metering device had good performance under these conditions of the permanent magnet magnetic field strength 150 mT,seed box moving speed 0.08 m/s, and the filling the position angle 110°. The simulation test value of the single seeding rate was 89.57%, and the actual test value was 87.93%. Simulation and test results were consistent. The results proved that it was feasible using discrete element method to analyze the performance of magnetic plate seed metering device, and the magnetic plate precision seed metering device could be used for small particles of vegetable seeds.

Abstract:An online detector of pesticide mixing mass concentration was developed based on the fact that different concentrations of solution had different refractive index. A 650 nm diode laser was used as the light source and a PSD as the light spot position detector. A PMMA triangular detector tube and a signal adjustment circuit based on OPA4277 chip were designed and manufactured. The experimental results showed that at the flow of 4.7, 5.4 and 6.1 L/min, the determination coefficient of position/concentration fitted curves were all above or equal to 0.983 1, and it increased with the flow decreased. At the flow of 6.1 L/min, the maximum deviation was 0.075 1 g/L and the average relative error was 8.99%, which showed that the developed detector could be applied to mixing mass concentration online detection.

Abstract:With the development of rice harvesting with large scale in China, high-efficiency of combine is more and more important. In order to satisfy the urgent demand of high-efficiency combine, the overall structure of a new crawler type combine with a feed rate of 4~5 kg/s was proposed and the combinational threshing and separating unit with a transverse tangential cylinder and axial rotor was designed. The design focused on the designing process of structural and operational parameters of tansverse tangential cylinder tangential concave, transition section between tansverse tangential concave and rotor concave, axial rotor and concave. Field test showed that the total loss was 1.47% and the damage rate was 0.2%, when the feed rate was 4.86 kg/s, which met the demands of the design.

Abstract:The discrete element method (DEM) simulation model of centrifugal metering device was established, and the simulation analysis was conducted on the motion processes of rapeseeds during the centrifugal metering device working. The law of rapeseeds movement was determined, and the relationships between rapeseeds weight inside the cone and critical speed, rotational speed and seeding quantity were also studied, respectively. The simulation results showed that with the increase of rapeseeds weight in the cone, the critical speed had a decreasing trend, and the seeding quantity had an increasing trend with the increase of rotational speed. The simulation results were consistent with the test results. It showed that using DEM to analyze the performance of the centrifugal metering device was feasible.

Abstract:The cavitation flow field in the axial flow model pump with tip clearance δ=0.5 mm was simulated based on modified SST k-ω turbulence model and cavitation model. The cavitation bubble distributions at different circumferential sections, meridional velocity distribution at impeller outlet and cavitation volume fraction were analyzed. Numerical and experimental results showed that the NPSH curve and tip region cavitation flow were predicted successfully. Cavitation inception in axial flow pump occured in the tip region, including blowing vortex cavitation, leakage flow cavitation, rolling region cavitation and tip leakage vortex cavitation. In the condition of cavitation number σ=0.451, the tip leakage vortex induced obvious cavitation cloud. The cavitation range of rolling region expanded with the decreasing of cavitation number gradually, and merged with the leakage flow cavitation area, and finally extended the cavitation bubble cloud to the entire suction side of the blades. The meridional velocity at impeller outlet near the gap region decreased gradually, in the influence of the gap leakage flow, and was further declined with the decreasing cavitation number. In different cavitation conditions, the circumferential section cavitation area coefficient of the blade, ranging from the hub to the tip, increased primarily, nd decreased afterwards. In the tip region, cavitation area coefficient bursted to the peak and dropt rapidly.

Abstract:The action mechanism of elastic dentations was analyzed using elastic dentations-roller-type sugarcane leaf sheath-stripping device. The tearing and stripping of leaf sheath were studied by further kinematic analysis of elastic dentations. The virtual prototyping experiment was carried out using ADAMS software to analyze the contacting situation between elastic dentations and sugarcane stalk. The impact of velocity changes of elastic dentations and center distance between two leaf stripping rollers on leaf sheath-stripping was obtained. The results of kinematic and simulation analysis were verified by high-speed photography test and physical prototype leaf-stripping experiments, which contained the single factor experiments of center distance between two rollers and rotate speed of leaf-stripping rollers. The results showed that when the center distance between two rollers was 310 mm, in the process of elastic dentations contacting sugarcane stalk, the elastic dentations slided down along the surface of sugarcane under the action of linear velocity difference in y direction Δvy=3.91~5.87 m/s, which was conducive to make leaf sheath tear along the direction of fiber. Meanwhile, the elastic dentations slided along the axis of stalk similarly because of linear velocity difference in x direction Δvx=4.61~7.54 m/s, which could make it scrape from the stalk. The result of the comprehensive leaf-stripping experiment proved that the impurity rate was less than 7% and the stalk broken rate was less than 15%. When the elastic dentations separated from the stalk, the linear velocity difference exerted on leaf sheath by elastic dentations increased as four to five times, which could help leaf sheath strip.

Abstract:Since ditch plow of direct rapeseed seeder would directly affect ditch quality and power consumption, a ditch plow and an optimized plow were designed and studied comparatively. The basic structure of the ditch plow was investigated and the characteristic of the digging-type surface of ditch plow and the smashing-type surface of the optimized plow were comparatively analyzed. Furthermore, taking traction resistance, plowing specific resistance, and power consumption as the evaluation indices, the experimental research on the impact factors of forward speed, ditch depth, ditch width, soil firmness were conducted by the high speed digitized soil bin platform. The experimental results showed that the greatest impact factor on traction resistance and plowing specific resistance was ditch depth, and the greatest impact factor on power consumption were forward speed and ditch depth. The traction resistance, plowing specific resistance, power consumption of the optimized plow were all only 35%~50% of the ditch plow’s respectively. The research conclusion had great theoretical value and practical significance to the optimization of ditch plow and the power consumption reduction of precision rapeseed planter.

Abstract:Acting force of soil is a complicated variable under vibrating working condition. In order to study the effect of penetration angle, amplitude and vibration frequency on acting force of soil and traction resistance, the soil was taken as viscoelastic material. The mechanics model for vibratory subsoiler and soil system was established considering piecewise acting force of soil. It adopted asymptotic method and numerical integral to solve and analyze this model, and the results showed that when the penetration angle was 45°, the amplitude was 0.001 m and the vibration frequency was 10 Hz, acting force of soil was relatively small. A vibratory subsoiler was tested in site to verify the correctness of the model through comparison of the simulation data and experimental data. The analysis further shows that the vibration can be used to reduce acting force of soil and traction resistance of tractor and improve quality of soil subsoiling.

Abstract:Hydrogeological survey and geochemical technology were used to investigate the relationship among recharge, runoff and discharge and hydrochemical characteristics of the groundwater in the Wuwei basin of the Shiyang River. And the response of hydrochemical evolution law to water circulation update was discussed. The results indicated that the TDS (total dissolved solids) values were between 131 and 1 750 mg/L, gradually increasing along the flow direction. The hydrochemical types showed an obvious zonation from the upper reaches to lower, which gradually changed from HCO-3-SO2-4-Ca2+-Mg2+ to SO2-4-HCO-3-Mg2+-Ca2+. Kriging interpolation of GIS was used to simulate the variation of the TDS of the survey region from 1989 to 2009. The results showed that the TDS in the south basin gradually increased as time went by, while there was an increasing trend at the earlier years, followed by a drop in the north basin. The TDS increased gradually along the flow direction from the piedmont to tail. As a result of the runoff leakage supply to the groundwater, the salinity along the bank of the Shiyang River was significantly low. The formation cause of the chemical components of the groundwater was due to the dissolution of halite, plaster, dolomite and calcite, also influenced by evaporation, ion exchange and sedimentary. Decline rate of groundwater storage capacity and groundwater depth was 3.04×108 m3/a and 0.47 m/a, respectively. With the increase of groundwater depth, the TDS value showed a trend of decrease and the drop rate was between 11.12~50.41 mg/(L·a).

Abstract:In order to study the spatial parameters of the distributive hydrological models among the ecological influences of regional farmland under the condition of water-saving practices in large scale irrigation district, the Bayesian neural networks and back-propagation artificial neural network models were applied to establish regional pedotransfer function models. Based on the relationship of measured soil characteristic contents, soil particle percentage, organic matter and bulk density, the adaptability of these two kinds of ANN models were evaluated through simulated and predicted values statistically, accompanied with the SWRC figures. Results indicated that the BP and BNN were both feasible PTFs methods. The training simulated accuracy of traditional BP model was better than that of BNN. However, the predicted accuracy of BNN model generally was better than the BP model. Furthermore, the predictive accuracy of BP model was significantly influenced by the number of input factor groups. But there were little influences on different input factors of BNN model. So, the BNN showed good robustness for the simple inputs. Besides, the predicted SWRC was better fitted with measured and VG fitted curve than that of ANN. Thus, the BNN model was better than the traditional artificial neural network model. It had better adaptability in the pedotransfer function establishment when only soil particle distribution was used. All showing that the BNN method was a practical method for regional pedotransfer function establishment.

Abstract:The lettuce yield and root distribution were studied in four cultivation substrates under drip and micro-sprinkler irrigation. And the vertical distribution model, lettuce yield and root length density model, and the differences and the similarities of root density relative distribution on profile were analyzed. The obtained results showed that the substrate moisture mainly distributed in lower level and evenly in 0~15 cm respectively under drip irrigation and micro-sprinkler irrigation. The lettuce root length density cultivated in compound substrates were higher 27% at least than that in pure vinegar cultivation. More than 71% of the root system was mainly distributed in shallow substrates(0~6 cm) under micro-sprinkler irrigation. The lettuce yield cultivated in compound substrates were higher 10% at least than that in pure vinegar cultivation, and was higher 22% at least than micro-sprinkler irrigation in spring, while it was lower 11% at least in summer.

Abstract:The leaf area index (LAI) and specific leaf area (SLA) simulation model of processing tomato with drip irrigation were developed based on the accumulated physiological development time after emergence (PDT). Then a simulation of leaf area, dry matter production and accumulation of processing tomato with drip irrigation was developed based on physiological and ecological processes of photosynthesis and dry matter production simulation model. The results showed that when using the model based on PDT, the coefficient of determination (R2), root mean squared error (RMSE) and modelling efficiency indexes (ME) between simulated and measured leaf area index based on the 1∶1 line were 0.926 5, 12.87% and 0.972 4, respectively. However, when using the model based on SLA, the R2, RMSE and ME between simulated and measured LAI based on the 1∶1 line were 0.675 8, 42.24%, and 0.712 4, respectively. When using the model based on PDT, the R2, RMSE and ME between simulated and measured aboveground dry matter weight based on the 1∶1 line were 0.990 3, 11.91% and 0.990 1, respectively. However, when using the model based on SLA, the R2, RMSE and ME between simulated and measured aboveground dry matter weight based on the 1∶1 line were 0.895 6, 31.29% and 0.750 4, respectively. Compared with the SLA method, PDT method to improve the processing tomato leaf area index prediction accuracy while also improving the prediction accuracy of the aboveground dry matter weight.

Abstract:Runoff and sediment data from 1987 to 2010, 143 flood events of Qiaozi East watershed (QE) on the loess plateau were used to investigate the relationships among rainfall, runoff and suspended sediments. K-means clustering of different rainstorm patterns was used to differentiate watershed runoff and sedimentation features and to quantify the impacts of erosion control practices on runoff and sediment production. The results indicated that the precipitation (P) and the maximal 30 minutes rainfall intensity (I30max) were the most relevant factors to runoff and sediment responses. The rainfall events were divided into four rainstorm patterns, as Pattern Ⅰ (low P and low I30max), Pattern Ⅱ (high P and high I30max), Pattern Ⅲ (high P and low I30max) and Pattern Ⅳ (low P and high I30max). The runoff generated by the storms, in term of peak discharges from low to high were in the order of Pattern Ⅱ storms, Pattern Ⅳ, Pattern Ⅲ and Pattern Ⅰ. Pattern Ⅱ, though the fewest in occurrences, produced the most sediments while Pattern Ⅳ, Pattern Ⅲ and Pattern Ⅰ storms produced limited sediments with no significant differences. The soil and water conservation practices significantly reduced runoff and sediment of the watershed, especially for the highest sediment production events of Pattern Ⅱ.

Abstract:Experiments were carried out to investigate anaerobic fermentation hydrogen production process and its metabolic regulation ways with taking Enterobacter aerogenesenes as pure strains and using glucose as substrate. The experiments were conducted to study at different temperatures (25℃,30℃,35℃,38℃), initial pH values (3.5,4.5,5.5,6.5), mass ratio of glucoses (G) and protease digestion (2,3,6). The results showed that Enterobacter aerogenesenes had a certain acid-resisting in the pH value range of 7.0 to 4.5. Moreover, fermentative hydrogen production cycles of Enterobacter aerogenes was very variable (between 68 h to 156 h) under different technical conditions. The optimum conditions of the shortest fermentative hydrogen production cycle of 68 h were as follows:the temperature was 35℃,the pH value was 6.5, meanwhile, the carbon-nitrogen ratio was 3. Based on these conditions, hydrogen production rate and hydrogen conversion rate could reach to the value of 261.5 mL/g and 2.1 mol/mol.

Abstract:Ａ laboratory scale of multi layer bed fermentation reactor was designed to study the influences of the layering and thickness on biogas characteristic of dry anaerobic fermentation using pig manure as fermentation substrates and straw as regulate material under the leachate recirculation conditions. The results showed that the bed layer anaerobic fermentation had significant impacts on cumulative gas production, the highest Nissan’s volume, and methane content in the gas characteristics of raw materials. When the thickness of bed layer changed from 250 mm to 150 mm, the cumulative gas production rate increased from 135.7 L/kg to 172.1 L/kg, increased by 26.8%. The highest Nissan’s volume increased from 97.4 L to 111.9 L, arose 14.9%, but had no obvious influences in average daily gas production. The highest methane content could be increased by 9% and the time of highest methane content had been advanced with the decreasing of thickness of bed layer significantly. Stratification of fermentation bed had a significant effect on leachate pH and COD value. With the increases of bed thickness, the pH value of three different groups of thickness treatment, 250, 200 and 150 mm, increased by 8.6%, 6.5% and 4.8% respectively from the initial value and the COD dropped by 21.0%, 15.0% and 14.0%. The thickness of bed layer affected leachate infiltration and backflow effect significantly.

Abstract:Rheological curves of pig manure with different solid holdup and temperatures were measured by a rotational viscometer. The effects of solid holdup and temperatures on the rheological behaviors were studied. The results indicated that pig manure behaved like pseudoplastic fluid and followed the power law model. The apparent viscosity showed an “upward growth” trend with the increase of solid holdup, but the temperature had little influence on it. There were some critical points on viscosity and solid curves, and they could be used as the standard of non-Newtonian fluid (pig manure) regarded as Newtonian approximately. There were also some critical D values on viscosity and shear rate curves, proposing that they could be used as definition of dead zone. The mechanism for temperature affecting apparent viscosity was discussed. Finally, the relationship between analyzed apparent viscosity and solid holdup and shear rate with the help of multiple nonlinear regression were analyzed, and a mathematical model was established and fittted well with experimental results, which provided the relationship of physical parameters in the functional form for process design and optimization involving non-Newtonian fluid (pig manure).

Abstract:The abnormal egg, blood-egg, has the internal optically active anomalies blood spots. A detection system based on Vis/NIR spectroscopy was designed for eggs’ internal quality inspection. Then, spectra data of 40 brown normal eggs and 60 artificial abnormal eggs obtained by injecting a small amount of blood ingredient were collected. Three analytical methods: the traditional discrimination method using blood value, discriminant partial least squares analysis (DPLS) and least squares support vector machine (LS-SVM) combined with spectral information and eggshell color information were compared for discrimination analysis. The final results showed that the discrimination rate based on LS-SVM method was 90.0% for normal eggs and that was 91.7% for blood-spot eggs, better than the results using traditional discrimination analysis methods. The results suggested that LS-SVM was an effective analytical tool in detecting blood-spot eggs with brown eggshell.

Abstract:Orthogonal experiments were designed to study the effects of temperature and velocity on the mechanical characteristics of brown rice, and the crack additional percentage of brown rice changing with drying condition and moisture content. The results showed that the modulus of elasticity was effected by both moisture content and drying conditions. The crack additional percentage of brown rice dried by superheated steam was closed to that of brown rice dried by hot air. Compared with conventional hot air drying, the crack additional percentage of brown rice dried with superheated steam was not worsen although the high temperature used, which had the advantages of higher drying rate and lower energy consumption. It was concluded that the superheated steam drying was a potential technology for drying rice.

Abstract:An online detection system based on dynamic weight measurement and graphic processing skill was developed. The developed system weighted dynamically the mass of egg sample using strain gauge weight and calculated major-minor-axis of egg through image generation. Comparison of the egg long axis and egg mass by different methods proved that the online system had a strong robust. Sample of 117 eggs were used to check the system, with mass error of ±1 g, minor-axis error of -0.5~0.7 mm and major-axis error of ±0.6 mm. The correct classification rate of XL grade, L grade, M grade and S grade were 100%,100%,93.84% and 100%. The detection velocity was 4 eggs per second. Experiments show that the online detection system meets corresponding standards.

Abstract:The overall structure and working principle of multiple sources microwave combining with hot-air fluidized drying test device were described. The design of microwave drying chamber, the coupling transmission position of six magnetrons, and the vibrating fluidized device system were analyzed in detail, and their specific structure and main parameters were confirmed. The total mode number and quality factor of the microwave drying chamber were 106 and 1 398 respectively. The microwave field of six magnetrons single-side radiating microwave energy was more uniform, and the frequency of vibration motor could be adjusted to led materials uniform fluidized for different shapes and sizes of materials, so that the materials more uniformly absorbed the hot-air and microwave energy. The results of carrots performance experiment proved that the moisture contents difference of dried carrots was within 1.22%, and the dried product rate of maintaining carrot original color, smell and taste reached 88.63%.

Abstract:Differential scanning calorimetry was used to determine the glass transition temperature (Tg) of vacuum-dried yacon powder with (yacon:maltodextrin total solid mass ratio of 1〖∶1) and without addition of maltodextrin (MD). GAB model and Gordon-Taylor equation were fitted to the sorption isotherms and Tg data, respectively. The state diagram was constructed to clarify the effect of MD on the critical water activity (CWA) and critical water content (CWC) of YP and YP-MD. The results showed that Tg decreased with increasing water content. Tg decreased from 15.8℃ to -72.6℃ as water content of YP increased from 5.95% to 30.88%. Tg decreased from 30.5℃ to -53.5℃ as water content of YP-MD increased from 5.11% to 27.66%. Addition of MD significantly increased the Tg of yacon powders. At temperature of 25℃, the CWC and CWA of YP and YP-MD were 0.045 5 g/g, 0.12, and 0.072 3 g/g, 0.27, respectively. Therefore, the addition of MD could significantly increase the CWC and CWA, and then improved the storage stability of yacon powder.

Abstract:The objectives of this study were to use the combining osmotic dehydration pre-treatment with freezing technique to improve the quality of frozen mangos. Based on mass transfer of mangos during osmotic dehydration, glucose was chosen as the osmotic agent and mangoes were osmosed in glucose solution at 30℃ for 60 min prior to freezing. The experiments indicated that the osmo-dehydrofrozen samples obtained much better results than that of the conventionally frozen samples with shorter freezing time, lower melting point and higher freezing rate. The quality assessment showed that the osmotic dehydration pretreatment significantly improved the quality attributes of frozen mango in terms of color, hardness, drip loss, vitamin C content and other physical properties compared to the untreated or the blanched ones. In addition, the osmo-dehydrofreezing could inhibit the polyphenol oxidase activity and improve the peroxidase activity.

Abstract:The improvement of esters content in cider by adding the nutrients into the apple juice during fermentation was investigated. By conducting the Plackett Burman experiment design, the factors affected 〖JP2〗the production of esters significantly, were selected, i.e. leucine, glutamine, pyridoxine and zincchloride. Subsequently, the steepest accent design was conducted to determine the central points of the four selected factors. The central points were 35 mg/L for leucine, 90 mg/L for glutamine, 0.3 mg/L for pyridoxine and 1.25 mg/L for zincchloride. The factors were optimized further by conducting the quadratic rotating combined design experiment. The optimizing condition was that adding 34.8 mg/L of leucine, 84 mg/L of glutamine, 0.24 mg/L of pyridoxine and 1.30 mg/L zincchloride to the fermentation liquor. Under this optimizing condition, the content of esters in the final cider achieved 5.29 mg/L.

Abstract:The effects of superfine grinding on physicochemical properties and hypoglycemic activities in vitro of dietary fiber of balsam pear (DFBP) processed by extrusion were studied. Soluble dietary fiber content，water holding capacity and swell ability of superfine grinded dietary fiber of balsam pear (SGDFBP) in different time were analyzed. Glucose diffusion，α-amylase and α-glucosidase activity were also analyzed to assess the hypoglycemic activities of SGDFBP. The results showed that the soluble dietary fiber content，water holding capacity and swelling capacity of SGDFBP were 17.04%，16.29 mL/g，and 17.20% respectively, when the d50 of SGDFBP was 20 μm. X-ray diffraction pattern showed that the ratio of non crystalline area of SGDFBP increased during superfine grinding. Inhibition of glucose diffusion and reduction in enzymatic effect of α-amylase and α-glucosidase induced by DFBP were intensified by superfine grinding. Different ingredients of SGDFBP had different functions in hypoglycemic activity, especially pectin had better one. Superfine grinding processing could effectively improve the physicochemical properties and hypoglycemic activity in vitro of DFBP.

Abstract:Vegetation temperature condition index (VTCI) takes the effects of NDVI and LST into account, and is applicable to drought monitoring in the Guanzhong Plain, Shaanxi, China. VTCI provides a scientific basis for drought relief and crop yield estimation in the plain. Based on the research of correlation of the weighted VTCI and winter wheat yield, and SARIMA drought forecasting results, the winter wheat yield forecasting models were developed at intervals of 1 ten-day, 2 ten-day and 3 ten-day before the harvest. The results showed that the yield forecasting results and yield monitoring results had a good agreement. The forecasting accuracy was reduced with the increase of the forecasting interval and the maximum relative error of the yield forecasting results of the 3 ten day was 3.27%, which indicated that the developed models could be used to forecast winter wheat yield at 30 days before the harvest.

Abstract:The winter wheat early growth period consists of reviving stage, early jointing stage and later joint stage, which is the most important period for precision management. It is significance to understand the growth status of winter wheat and provide accurate and scientific data for precision agriculture in the early growth period. The general model used to describe the canopy reflectance and chlorophyll of early growth period was necessary. The linear regression models, which used character wavelength as independent variable, were constructed. The PLS(partial least square) algorithm was applied to construct multiple regression models, which used the vegetation index as the independent variables. All models were used to predict the chlorophyll content in the same period and different periods. The better general model was found according to the predictive effect. According to the curve of correlation between reflectance and chlorophyll content, the curve ranged from 500 nm to 600 nm contained the extreme values. The linear regression independent variable was 550 nm selected from this range. The linear regression model of the reviving stage predicted accurately in the early jointing stage and poorly in the later jointing stage. In contrast, the multiple regression prediction model of the reviving stage had more versatile. It showed the satisfactory predication in early and later jointing stage. In order to improve the accuracy of predication in different stages, MPRI(mobil PRI) was developed to construct the multiple model with NDVI(normalized differential vegetation index) and RVI(ration vegetation index), instead of TCARI. The test results proved that MPRI was simpler than TCARI on the parameter and the structure. The multiple model, made by MPRI，NDVI and RVI was general for the winter wheat growth periods.

Abstract:In order to configure wireless sensor networks system and node deployment in greenhouse, this paper researched propagation characteristics of 2.4 GHz wireless channel at different directions and heights in greenhouse of green peppers. Received signal strength and packet loss numbers were investigated by field testing measurements at three directions and two heights. Regression analysis results showed that the radio channel propagation characteristics in different directions and heights of green peppers accorded with logarithm distance path loss model, and the fitting correlation coefficients between computational values and measurement values were between 0.900 7 and 0.947 3. Different heights of sensor nodes in the green peppers determined the radio wave propagation characteristics. Besides, validation results showed that it was the best to deploy the sensor nodes antennas at the top of green peppers canopy or above of it in greenhouse. This research can provide technical support for WSN application in greenhouse.

Abstract:In order to judge the degree of plant disease stress effectively and determine disease situation, according to plant acoustic emission phenomenon, cylindrical and spherical non-conformal acoustic holography experiment model was established based on the distributed source boundary point method near-field acoustic holography technology. Single sound source and double sound sources were simulated respectively. The parameters, such as the holographic cylindrical radius, the number of measuring points on the holographic face, the number of nodes on the reconstructed spherical surface, the distance from fictional special point sound source to nodes on the reconstructed spherical surface and so on should be adjusted to obtain the practicable experimental parameters. The simulation results showed that the method could identify and locate the position of the acoustic emission source accurately. According to the experimental parameters, the signal acquisition acoustic holography experiment system was established based on DSP, signal was analyzed and processed based on LabView software platform.

Abstract:It is important to construct virtual plant model based on the interaction between plant and environment for greenhouse environment control. Taking the greenhouse cucumber growth as an example, it would obtain plant environment interaction information with data pre-processing and association analysis method. According to the crop development theory model, the information response model as well as information feedback model could be established. Moreover, the models could be coupled with the plant development process. The plant topological model and organ morphological model would be founded using regularization method and object-oriented technology, and the virtual plant model could be constructed. The experimental verification results indicated that the goodness of fit of models could be up to 95%, and improved that the presented method was effective in simulating the plant development under the interaction of environment, which also provided valuable evidences for dynamical control and prediction of greenhouse environment conditions fitting to plant growth.

Abstract:Since the current agricultural image sensor was low resolution and lack of adjustable control function, a high-resolution agricultural image capture node was designed based on ARM, OV hardware platform, and embedded Linux operating system. Both the hardware and software architecture of the image capture node were designed, the node could be controlled easily. It had better control function than traditional image sensor, which had five kinds of white balance control mode, seven levels of brightness, five levels of contrast and five levels of contrast and five levels of saturation effects. It could satisfy the needs to control image acquisition, and provided a convenient remote dynamic application in different scenarios to adjust image capture effects. Experimental results showed that the node could capture the 2 048 pixels×1 536 pixels of image. It also had the advantages of small volume and low cost. This node could be widely used in agricultural image capture, particularly suitable for wireless image sensor networks, crop images and video in real time monitoring.

Abstract:The number of wheatears in each square meter is a main parameter of grain production estimate. In order to intelligently calculate the number of wheatears in certain parts, a in-field wheatear counting method based on image analysis technique was designed. Firstly, several color features such as normalized difference index were analyzed to get suitable features, which were used to extract wheatear from original image. Secondly, a comparison of the five texture features (energy, contrast, homogeneity, entropy and relation) was performed and the appropriate features were selected to segment wheat images. Finally, the number of ears was calculated. In this step, erosion and dilation operations in binary mathematical morphology were performed so as to clear impurities and awns. Hole filling algorithm and thinning algorithm were used to get unbroken wheatear and its skeleton. Corner detection algorithm was selected to get the corners of skeleton with the purpose of estimating the wheatear number of connected region. The advantages and disadvantages of the color segmentation and texture segmentation were deeply analyzed. Twenty images with 71×92 pixels were used to evaluate the run-time of color segmentation and texture segmentation. The former took 16.97 ms and the latter took 17.76 s. To validate the effectiveness of the designed method, 35 drilling wheat images and 35 broadcasting wheat images were tested, and the average counting accuracy data for drilling wheat and broadcasting wheat were 95.77% and 96.89%, respectively.The experimental results showed that the color feature and the texture feature could be used to extract wheatear from original wheat image, and the color segmentation was faster than texture segmentation but less environmental adaptability. The corners of skeleton had close relationship with the number of wheatears in connected region.

Abstract:Extracting boundary curves of holes from point based models is one of the basic and key technologies in the research field of digital geometry processing. An algorithm was presented for extracting the boundary curves based on the properties of point clouds and deriving a combined criterion for automatic hole detection. First, the k-neighboring points for each point were collected in a given point-based model and then the normal of the point-set surface at the point is evaluated. For each point, several essential criteria were combined, such as the largest angle criterion, half-disc criterion and shape criterion respectively, into a weighted blended probability. Finally, the boundary curves of holes were constructed by searching the nearest point strategy and the boundary points were connected by a poly-line to generate the boundary curves. Experiments show that this algorithm can run stably and robustly, and can extract various hole boundary curves from point cloud models.

Abstract:In order to improve the commonality of research findings in the mechanical joint properties, the equivalent material properties of the mechanical joints were proposed. Based on GW contact model and Hertz-Mindilin contact theory, the Young’s modulus and the Poisson’s ratio of the equivalent material properties were deduced by the stiffness per unit area in the joint, which was obtained by the experiment. A bolted structure was taken as the example. The deformation of the structure was measured and analyzed under the different loads, which including the deformation of the structure’s joints. The comparison between the results of calculation and experiment validated the feasibility and effectiveness of the equivalent materical properties of the mechanical joints.

Abstract:A drive system of spherical robot was designed by which the horizontal obliquity of roll axe could be adjusted vertically to control turning and used to identify the roll axe as unique variable. Since only two control variables, the horizontal obliquity of roll axe and the rotate speed of drive motor, were used in the control model, the control strategy could be given without any complex operation. In order to deal with the problem of path tracking, the concept of relative curvature radius was introduced as a turning control index. Based on the existence and uniqueness theorem about plane curve theory in differential geometry, path tracking was actualized by adjusting horizontal obliquity of roll axe so as to make the track and path had the same relative curvature radius in the corresponding points with same arc length from respective original point. The arc length of the track from original point to the present position, needed to choose relative curvature radius in control process, could be obtained from the moving time, and no sensor was needed for measuring. The control strategy was proved to be correct for several especial values of relative curvature radius, and the feasibility of the control strategy was also validated by a simulation result.

Abstract:An automatic matching approach of locator scheme was suggested on the basis of fixture cases. Firstly, in light of the number of locating points, the processing information matching index of locating reference was proposed. Secondly, according of the geometrical and topological relation, the geometrical information matching matrix of workpiece was proposed from three levels of point, line and surface. And then, the fitness index of workpiece and corresponding weight were constructed. Thirdly, the decision function of locator scheme was formulated with combination of the processing information matching index. Finally, some typical examples were used to illustrate the proposed automatic matching approach of locator scheme in detail.

Abstract:In order to quickly establish a pressure control algorithm with good performance for proportional solenoid valve, a compound control algorithm with the combination of open loop control and closed loop control was presented. The algorithm improved the control performance by making full use of the valve response characteristics. Control algorithm design process and control models were established. Unlike the conventional control methods which took the error as the only input, the input of compound control algorithm consisted of both the goal value and the error value. Valve respond characteristics were tested. The open loop control table was established based on the steady-state characteristics of the valve and the saturation in steady-state was eliminated by the open loop control table. The closed loop control value and delay effect compensate value were calculated according to the transient characteristics and the closed loop controller was used to revise the model error and improve the dynamic response. Experiment results showed that the performance of compound control algorithm was accurate, fast response and robust.

Abstract:The new kind of roller pump is the combination of radial ball piston and vane pump. Based on the characteristics analysis of elliptical area and length, the volume formula of double-acting elliptical orbit roller pump was deduced, and the flowing and pulsating of the pump were obtained. At last through the simulation , the effect of the structural dimensions on the flowing and pulsating of the pump was received. The analysis results indicated that the flowing of the pump is the five times of that of radial piston pump, and the 1.5 times of vane pump at the same structural dimensions. And the pulsation rate was slightly increased. There was a phase difference comparing with radial piston pump and vane pump, which was 13° in the article. The pulsation was generally reduced with the increasing of rollers’ number, but it was larger with the number being a multiple of 4. The output characteristics of the analysis results provided a theoretical basis for the roller pump structure optimization and noise and vibration reduction.

Abstract:The intrinsic geometrical quantity of macroscopic soil-engaging surface of bulldozing plate plays a decisive role for its geometrical and dynamic characteristics. Three forms of macroscopic soil-engaging surfaces with the arc, parabola and bionic curve were designed and manufactured. The working resistance was measured with a laboratory soil bin. The intrinsic geometrical quantities of the macroscopic soil-engaging, including the first base quantity (E, F, G) and the second base quantity (L, M, N), were calculated based on the parametric equations of the three macroscopic soil-engaging surfaces. It was discovered that E value in the first class of the base quantity and the value of L in the second class of the base quantity were important factors influencing the working resistances of soil-engaging surfaces. The value of E and L of the bionic soil-engaging surface possessed more complex trend, also obtained lower working resistance accordingly. However, the relatively simple arc bulldozing plate had a relatively large working resistance.

Abstract:Based on the tamping device with hydraulic excitation and independent clamping movement, an electro-hydraulic exciter composed of spin valve and micro-displacement double-functioned hydraulic cylinder is designed. Considering the working principle of the electro-hydraulic exciter, a theoretical model is established according to the two throttles principle and the related experiments are validated. According to the analysis of excited waveforms, the conception of saturation is first proposed. In addition, saturation of excited waveforms is analyzed and optimized through working frequency and axial length of orifice. The results indicate that the waveforms are approximately symmetrical because of inertial force and certain amplitude and slope of triangle wave, and sine wave and trapezoidal wave are achieved through adjusting suitable working frequency and axial length of orifice. Besides, axial length of orifice increasing or working frequency decreasing leads to increase of saturation. Saturation and axial length of orifice are nonlinearly related. Nonlinearity decreases with the increase of working frequency.

Abstract:Particle image velocimetry (PIV) technique was used to test the gas-liquid two-phase flow field dynamics above the membrane approach in six different aeration intensity conditions. The liquid flow field above the membrane approach was tested, and the membrane surface mass transfer, thickness of concentration polarization boundary layer, shear stress and some other mass transfer parameters of membrane surface were calculated. The conclusion shows that the aeration intensity and liquid phase velocimetry strongly influence the characteristic of membrane surface mass transfer, and the aeration intensity increased in a certain range can make the membrane surface mass transfer characteristic strengthen. The paper provides experimental data and research experience for optimization design of membrane bio-reactor.

Abstract:A wind piezoelectric energy harvester based on vortex-induced vibrations was studied. The tandem arrangement of two circular cylinders was designed to enhance the amplitude of the pressure fluctuation. The Helmholtz resonator was used for magnifying the wind pressure in the wake region. The flow energy was converted into electrical energy by piezoelectric conversion with oscillation of a PVDF film. The fluid dynamics behaviors of the internal flow field subjected to different wind speeds were analyzed using computational fluid dynamics(CFD) numerical method. Numerical analysis and experimental results showed that the pressure fluctuation in the case of two circular cylinders could reach up to nearly 2 times as that of a single circular cylinder, when the coupling factor L/D=2.2 and subjected to the same wind speed. As the gas in the cavity induced by the oscillatory flow, the gas pressure increased with the wind speed while the vibration frequency kept the same with the natural frequency of the resonator.