Abstract:In order to realize the servo control of electro-pneumatic clutch actuator in an automated mechanical transmission, an electro-pneumatic clutch actuator system was established. By performing a simple sliding mode control law of dead zone directly on the established system, the tracking control of the electro-pneumatic clutch actuator without unnecessary control chattering was achieved. Meanwhile, the load characteristics of clutch could be estimated indirectly by the pneumatic driving force during trajectory tracking. In theory, the estimation error of load characteristics obtained by this approach is small. So, the clutch load characteristic is closer to the actual value in the trajectory-tracking control. Tests show that the proposed model-based integral sliding-mode controller with the estimation of clutch load characteristic introduced can improve the tracking accuracy to a large extent.

Abstract:Electric power steering (EPS) system driven by permanent magnet synchronous motor (PMSM) has become the future trend of development. In order to adapt the characteristics of AC motor, dynamical-returnability characteristics based on fuzzy rules were designed. The extended Kalman filter (EKF) was introduced to estimate the stator flux and location, and the direct torque control (DTC) was adopted to control PMSM, so as to accelerate the response rate and precision. Referring to the national standard, simulation of this system was carried out on steering portability and return performance, the results show that the effect of the proposed system is significant under PMSM assisting, the steering wheel average operating torque is reduced by 45%, and the wheel self-turning time shortens 50%. Finally the bench test was experimented and shows that the whole system dynamic operates well and can fully complete the power control target.

Abstract:A kind of Hilly power chassis with variable ground clearance and wheel track (VII-HPC) was designed to adapt to hilly terrain and agronomic characteristics of various types of crops. Hydraulic four wheel steering scheme without steering trapezoid has been proposed. To reduce turning radius and achieve same rut steering, the steering strategies are two ipsilateral wheels steering with a reverse and equal angle. The displacement relationship of right and left steering cylinder would be optimized by genetic algorithm to achieve Ackermann steering. The rotation of the steering wheel is not too large to avoid movement interference, which the minimum turning radius of the same wheelbase ordinary tractor was provided a reference. After change ground clearance, the wheel deflected around the kingpin. The relationship between the effective turning angle in the horizontal plane and the displacement of cylinder should be redefined according to the geometric relation. The conditions to meet the Ackermann steering need to be re-discussed because the wheelbase and track of the chassis would be altered after VII-HPC change ground clearance and the track. Experimental results show that the structure of steering system and steering strategy is reasonable and feasible.

Abstract:In order to establish break-up model of multi-hole injection on gasoline direct injection engine, an analysis and evaluation on FIPA model, Huh Gosman model and KH-RT model has been done. The second break-up model was built for gasoline direct injection in cylinder, and the primary break-up particle size distribution formula was also built based on injection pressure. So the break-up model of gasoline direct injection in cylinder was established. At last, by carrying out capacity spray experiments, gasoline free spray experiments were done to verify the reasonability of the established model. It was found that Huh Gosman model has the best simulation results compared with other models. The droplets break relatively too fast with FIPA model and too slowly with KH-RT under the same simulation condition. After modifying Huh Gosman model, the simulation results showed close to the practical ones. At last, free sprays under different injection pressures were simulated with the above established model. Calculation results match well with the experimental results.

Abstract:To improve vehicle engine fuel economy，an organic Rankine cycle (ORC) system was designed to recover waste heat from heavy-duty diesel engines through their exhaust air. R245fa was selected as the working fluid after compared with several other organic fluids. A test platform for waste heat recovery was built, which includes an ORC circuit, an energy conversion and consumption device, a data measure and acquisition unit and a heat supply module. The feasibility of using R245fa as working fluid in the heavy-duty diesel engine ORC system was proved by experiments. The maximum power output of the system is 490W. The experiments indicate that the matching of the expander，the generator and the ORC system is the key factor restricting the power output. The system cycle efficiency increases with the evaporating pressure increase.

Abstract:This essay describes a new method, based on fuel consumption and AFR (Air-fuel ratio) measuring, to acquire the charge efficiency of internal combustion engine. In the method, the fuel consumption and AFR under steady condition are used to calculate the air inlet, and the air charge efficiency is calculated by definition. The equations of air charge efficiency and error analysis were built on fuel consumption and AFR. An injector flux calibration & testing system and a measuring system of fuel consumption and AFR were designed for a ZS157FMI-3 motor equipping with ZH600 engine electronic control system. The charge efficiency was tested through measuring mean and transient fuel consumptions and AFR. The efficiency test result indicates that the two methods of measuring fuel consumption have a good consistence for charge efficiency calculation, and the error estimation of the test results demonstrates that the efficiency results calculated from the fuel consumption and AFR have high accuracy, with the relative error below 0.5%. Since the charge efficiency acquiring way overcomes some inherent drawbacks of the common methods such as pressure wave method and velocity-pressure method, it offers more measure accurate in theory and better adaptability to different fuel types.

Abstract:The paper aims to deal with the numerical simulation of cavitation phenomena inside the centrifugal pump and analyze the development of cavitation based on improved cavitation model, Standard k-ε and RNG k-ε turbulence model. When cavitation flow and non cavitation flow were simulated and analyzed, the pressure of blades under incipient cavitation, developed cavitation and serious cavitation were gotten. The paper also gave the principle of incipient cavitation and divided the region into five cavitation regions based on bubble relative length. The results show that with the decreasing of inlet total pressure, bubble appears firstly in suction surface of the blade, and then moves along the blade profile, and next forms attached cavitation bubble. After this stage, bubble is gradually out of the mainstream movement and close to the pressure surface. Finally, the flow passage is filled with bubble, which hinders the flow. The number σ=0.3067 of incipient cavitation is a greater dimension hierarchy than that of σ=0.0281 under design condition. Seen from the impeller meridian plane, bubble appears firstly in the near the hub, goes towards forward cover plate, and attaches near the front cover. Cavitation in centrifugal pump is subdivided again into the five stages, that are incipient cavitation, critical cavitation, developing cavitation , complete cavitation, broken cavitation.

Abstract:In order to obtain the variation law of the acoustic emission signals under the centrifugal pump’s cavitation states, the research was based on the centrifugal pump cavitation test. The acoustic emission technology was adopted to collect and analyze the acoustic emission signals. Four typical features were extracted, i.e. event count, ringing count, frequency centroid and root mean square. Their relationships with the net positive suction heads of the centrifugal pump were analyzed in detail. The results show that these typical characteristic parameters change obviously under different stages such as before the occurrence of cavitation, cavitation first appearing and cavitation being fully developed. They firstly fluctuate a little, then increase or decrease substantially, and then there are large reducing or increasing trends respectively. This law can be used as a technical basis for identifying the cavitation conditions of centrifugal pumps with the acoustic emission technique.

Abstract:In order to study the flow characteristics in centrifugal pump at design condition, the inner unsteady flow was simulated based on high-quality structured grid and rapid prototyping technology by using the commercial software CFX．The results indicate that the method of unsteady numerical simulation can accurately predict the performance parameters of the centrifugal pump with the test. The maximum deviation of head and efficiency are less than 4% and 3%, respectively. Impacted by the impeller-volute coupling, the pressure pulsation in volute centrifugal pump has strong periodicity, and the basic frequency is the blade passing frequency. There is a similar pressure field between the impeller passage inlet and the middle of impeller passage, but the pressure distribution near the impeller outlet has a significant difference. Significant secondary flow phenomena exist in the volute and move forward with the mainstream.

Abstract:In order to gain the inner flow field of flow-ejecting self-priming centrifugal pump, a flow-ejecting self-priming centrifugal pump equipped with a jet in the front of impeller inlet was chosen as the study object. The geometric model including all parts was built up by Pro/E software. The turbulence model chosen was RNG k-ε turbulence model and the mesh independence was checked by six meshes with different grid number. The external performances and the inner flow fields under seven different working conditions were simulated by CFX 14.0. The profiles, such as static pressure and velocity, were obtained. Then, the numerical results were compared with the testing results gotten on open test bed. The results show that the errors of head, shift power and efficiency between the simulation and the testing under designed condition are 2.63%, 6.16% and 14.29%, respectively. The simulating and the testing power curves are almost horizontal lines and change slowly when the flow rate is smaller than 3.5m3/h. The absolute velocity distribution between the nozzle and the line segment is axial symmetry. However, between the diffusion section and the impeller inlet, the upper velocity is larger than the lower velocity. And the velocity of the flow entering the impeller inlets is not uniform. The location, L=0.148m, is a critical location where the static pressure is the smallest and the turbulence dissipation rate achieves its maximum value. The numerical results provide a directly theoretical guideline for the pump design.

Abstract:In order to solve the problem of bottom-vortex in the cube type suction passage of pump 4 types of vortex-elimination devices were designed based on the vortex tubes intensity conservation theorem. To verify the validity of these devices, the test-rig was set up for experiment and the high-speed photography was applied to the flow pattern of the suction passage with different types of vortex-elimination devices. The bottom vortices in the original passage were captured successfully under different operation conditions. The effects of 4 new vortex-elimination devices on the hydraulic performance of pump system were analyzed based on the energy test. The results show that the new vortex-elimination device can eliminate the bottom vortex, the flow pattern of flare and the hydraulic performance of pump system can be improved.

Abstract:The scaled model pump of TJ04-ZL-02 hydraulic model, which has been applied on the Tianjin same test-bed for South-to-North Water Transfer Project, was simulated base on fine calculation for tip region flow field and SST k-ω turbulence model, and flow field structure for tip leakage vortex as well as filed dynamic characteristics were studied. Numerical calculations and experimental results show that numerical simulations for clearance leakage and boundary layer flow based on SST k-ω turbulence model are relatively accurate. The power arose from tip leakage vortex is regard as differential pressure between the pressure side and the suction side of blade. For the pressure difference of blade leading edge is the largest, velocity of tip leakage flow is higher. The pressure difference between blade pressure and suction side is increased gradually with the increase of blade chord coefficient λ, and clearance leakage flow velocity as well as leakage vortex strength is decreased gradually. The local low pressure of blade tip region mainly occurs on vortex region of separated vortex near the pressure surface, as well as tip leakage vortex region at the lower part of blade suction side. The local low pressure region of blade suction side is getting further away from blade suction side with the increase of blade chord coefficient λ. The local low pressure region of blade rim near blade pressure side is mainly caused by separated vortex which is induced by blade tip corner， and the low pressure near suction side of blade is resulted from tip leakage vortex, and the process reveals the flow characteristic of tip leakage vortex for axial flow pump.

Abstract:An M-type section had been designed to reduce internal shock losses in the channel of votex pump. The reasonable M section was based on the theory of the same area, with the constant height, section of channel sharped like an M was more in line with law of fluid flow. The nearest distance of the wall of channel and the outlet of blades was 1mm. In order to research the inner flow in channel, computational fluid dynamics software CFX was adopted in the inner flow field analysis. Head, efficiency curve and velocity vector of rectangular and M-type channel were obtained from the simulation. The results show that the head and efficiency have improved; fluid flows more smoothly in the M-type channel; turbulence and small reverse spiral at the outlet of blades is less. However, the friction losses increase with the larger flow area.

Abstract:In order to investigate the influence of dividing pier on the hydraulic performance of a low-lift axial-flow pumping system，CFD method was used to simulate the three-dimensional internal flow of a low-lift pumping system with different outlet passages. The performance of the pumping system was estimated，and was compared with test data. Focusing on analyzing of the influence of dividing pier on the hydraulic performance of outlet passages and external characteristic of the pumping system, flows in two channels of the outlet passage are unequal to each other，the flow imbalance problem and the influence of velocity circulation on the hydraulic performance were analyzed as well. Results show that the dividing pier has great influence on the performance of the low-lift pumping system and should be avoided. Protrusive dividing pier makes the hydraulic loss of outlet passages increased and flow distribution more unequal. Backward extension of dividing pier does not influence the flow distribution, but makes hydraulic loss of outlet passage increase which induces degradation of the performance of the pumping system. Under the condition of zero velocity circulation, the hydraulic loss of outlet passage is in proportion to the square of flow, and the hydraulic loss is larger than that with velocity circulation and the flow is more complex. The internal and external performance of outlet passages has the relationship with the running condition of the pumping system，so it should avoid calculating the flow patterns of a separated outlet passage.

Abstract:Geo-statistics combined with classical statistics were applied to analyze the spatial distribution of soil nitrogen (N) and phosphorus (P) content under three different land uses in Chahe watershed at the lower Yangtze River. The results showed that soil N and P content distribution varied significantly in paddy, upland, and vacant land, while the coefficient of variation also varied greatly among the three land uses. All spatial distributions of N and P content values were anisotropic and directions of most long axes were northwest-southeast. Major ranges in topsoil were between 750~950m with the order of total P(TP)>ammonia N (AN)>total N (TN)>available P (AP)>nitrate N (NN). Higher content of TN was mainly concentrated in the southern part of the small watershed and the gradient direction was consistent with the direction of surface runoff, while distribution of TP was significantly affected by farming and soil particle movement, and the high level of TP was appeared in the accumulation area of the south of small watershed and the north of arid region. TN and TP showed similar structural characteristics under the three farmland types, while both the autocorrelation scales in paddy land were larger than those in upland. Variation of spatial autocorrelation scales showed good consistency with the coefficient of variation. Research results provided a scientific basis for the control of N and P losses in agricultural production and the establishment of non point source pollution model.

Abstract:There are some problems, such as how to use advanced methods, how to make less work, economical and reasonable experimental design and how to make representative sampling points during soil analysis. The above-mentioned problems are becoming research difficulties and hotspots in recent years. A research on spatial variability of soil hydraulic parameters basin scale in Jinghui Irrigation, Shaanxi Province was made based on GPS and Google Earth methods. The results showed that saturated soil moisture content and saturated hydraulic conductivity moderate variation in the regional scale show out moderate variability and strong spatial dependence. The best-fitting models for saturated soil moisture content and saturated hydraulic conductivity are spherical model and exponential model, respectively. As for the above two, the sample spacing of 2.38km and 7.14km are recommended.

Abstract:As the main reason for soil water erosion, the overland flow process should be simulated precisely to understand the mechanism of slop soil erosion process. Developed based on the kinetic theory, Lattice Boltzmann method has advantages of concise programming, parallel computing and complex geometric adaptability, etc. So its application in field of fluid motion becomes more and more extensively. The detailed steps about applying Lattice Boltzmann method to the movement of overland flow was given firstly, and then its validity was verified through artificial simulated rainfall experiment. The results indicate that if the time is processed by multi-scale approach and the space is not, the equilibrium distribution function is determined by the method of undetermined coefficients and multi-scale analysis, the distribution function about nodes of the upper boundary is replaced by the equilibrium distribution function through regarding the macroscopic upper boundary conditions as limiting conditions, and the distribution function about nodes of the lower boundary is set by extrapolation format of distribution function, Lattice Boltzmann method will successfully become a motion equation solver. The errors of runoff depth are within ±11%.

Abstract:A model simulating the transport of water and nitrate in soil under mulched drip irrigation of cotton was established and solved numerically by using the HYDRUS-2D package. The model was calibrated and validated by the field experiments conducted in Urumqi, Xinjiang Uygur Autonomous Region, China, during the cotton growing seasons of 2010 and 2011. The emitter discharge rates that progressively decreased from the inlet to the distal end along the dripline were discretized as a series of sequential segments each having an equal discharge rate. Assuming no lateral exchange of water in soil between adjacent segments, the model, which had been verified, was used to evaluate the effect of drip system uniformity and soil spatial variability on the distributions of water and nitrate in soil under arid conditions. The results indicated that the uniformity coefficients of soil water content and nitrate were observed in downward trend for drip system uniformity coefficients (Cu) of 0.60 and 0.80, while a relatively stable variation pattern was observed for Cu=0.95; the lower system uniformity the greater decrease in the uniformity coefficient of soil water content and nitrate following an irrigation event was observed. The uniformity coefficient of soil nitrate, which varied from 0.35 to 1.00, was substantially lower than that of soil water content. Meanwhile, the soil spatial variability in the experimental field increased the nonuniform distributions of the soil water and nitrate.

Abstract:The ecological restoration area in the west part hill area of the Loess Plateau was chosen for the object in this work. Neutron probe was used to test the moisture change in Pinus tabulaeformis forest soil under different rainwater harvesting and water conservation measures. The dynamic characteristics of soil moisture under different rainwater harvesting and water conservation measures, the deficit and compensation of soil moisture before and after rainy season were analyzed. Results show that soil moisture storage capacity under different rainwater harvesting and water conservation measures is significant different. The soil moisture under slope water harvesting measure is greater than those with other measures.The soil water storage deficit is alleviated under seven measures in July. Soil water storage deficit from 0～100cm is alleviated under slope water-harvesting and slope water-harvesting with water harvesting groove reversed. Results of this study indicate that slope water-harvesting has a significant effect on the effective use of precipitation. Film mulches mulch has a negative impact on the recovery of the surface soil moisture，but has an obvious effect on water conservation of deep soil moisture.Wallow-tail type runoff collecting pit is ineffective in increasing the efficiency of precipitation use and compensation of soil water storage deficit.

Abstract:In order to solve the problem of congestion in subsurface drip irrigation and to promote application of subsurface drip irrigation to forest or fruit industry, the design principle and the design requirements of model anti-clogging of subsurface drip irrigation system were proposed. These data of the system were obtained that the system pressure was 15~25kPa and the plughole spacing was 300mm, and that the distance between inner wall of protective tube and out wall of capillary was 40mm and the irrigation uniformity is more than 85% through experiment. Effects on the growth of Cabernet Sauvignon by the system show that anti-clogging subsurface drip irrigation (SDI) and drip irrigation under plastic film (MDI) compared with conventional drip irrigation (DI) can maintain the stability of soil moisture content in 20~60cm, and increase ratio of root to shoot and the effective root surface area, so as to accelerate root turnover and renewal, and enhance the absorptive capacity of plant roots to soil moisture and nutrient.

Abstract:Three kinds of biochar-based nitrogenous fertilizer(BBNF), which were composited with ammonium nitrate by simple-blending process, adsorbent process and reactive process, respectively, were produced. After that properties of the new BBNF were determined and their sustained release characteristics were evaluated. The results show that the pH values of all the three BBNF are all lower than that of the raw biochar. The BBNF prepared by reactive process loads maximum ammonium nitrate, followed by the BBNF prepared by adsorption process; the least is the BBNF prepared by blending process. The retention capacity of BBNF prepared by reactive process is better than the other two. The cumulative release rate of the three BBNF in aqueous solution is in line with the “S”-type release model. Compared with ammonium nitrate, all of the three BBNF have effectively controlled-release effect on nitrogen, and the BBNF produced by reactive process has the best effect.

Abstract:The object was to explore the efficient water-saving method of arabica coffee seedling, experiment of three levels of super absorbent polymer (SAP), i.e. high SAP (SH), low SAP (SL) and no SAP (SN), and three levels of irrigation, i.e. high water (WH), middle water (WM) and low water (WL), was designed, and the effect of SAP and irrigation on physiology, growth, dry mass accumulation and water consumption of arabica coffee seedling was studied. Results showed that, compared with SN, SL increases chlorophyll (Chl), carotenoid and root activity by 11.8%, 13.4% and 52.2%, but reduces soluble sugar (SS), malondialdehyde (MDA) and proline(Pro) by 24.9%, 24.3% and 55.8%, and also increases total dry mass and water use efficiency (WUE) by 31.0% and 35.9%, respectively; however, SH reduces Chl, carotenoid, MDA and root activity by 3.1%, 2.4%, 13.5% and 6.3%, and reduces total dry mass by 21.3% as well, but increases SS, MDA and WUE by 3.7%, 75.1% and 8.6%. Compared to WL, WM increases total dry mass, water consumption and WUE by 89.8%, 44.5% and 33.2%, while WH increases total dry mass, water consumption and WUE by 172.8%, 104.8% and 34.0%. Compared to CK (SNWL), SLWM has the largest increase of WUE by 112.7%, and increases total dry mass by 158.9%, as well as leaf relative water content, Chl, carotenoid and root activity by 24.4%, 19.5%, 25.8% and 149.9%, whereas reduces SS, MDA and Pro by 38.3%, 36.4% and 68.7%. Considering high efficiency water saving, SLWM is the optimum experiment combination.

Abstract:It is the primary factor to influence the completion and utilization efficiency of water and fertilizer for the root distribution in strip intercropping field. The effects of 3 treatments of high, middle and low irrigation quotas on soil water of different positions and root distribution were studied, and the characteristics of root distribution in different growth period were investigated, as well as the pattern of root distribution in vertical and horizontal direction based on cumulative root distribution curves. The results show that the average soil water in tomato side is obviously higher than corn side, and the soil water under mulch is also obviously higher than that under outside mulch; however, there is no significant difference for the soil water of different positions under mulch. With crop growth, there are the pattern of “no cross—small cross—full cross—small cross” for roots of tomato and corn; 60%~70% root concentrates in 0~30cm soil, and the quantity of total roots and the roots in 0~30cm soil are all increasing with the soil water, whatever root length density, root surface area density, root volume density and root weight density, yet there is the inverse for root distribution in 40~100cm soil. The cumulative root distribution curves show that the root grows down with the soil water increase and the root grows to the district among crops with crop growth except for corn in the last stage. The root distribution is large variation in different growth periods, and the soil water is also main factor to influence root distribution in strip intercropping field.

Abstract:The sensor for soil moisture measurement should have broad adaptability, and the soil moisture can be measured by the sensor upon the determination of the relationship between soil moisture and relevant variable. Five typical soils from different geographic locations of China were sampled for soil moisture measurement test with the near infrared sensor designed with 1940nm as measuring wavelength and 1800nm as reference wavelength. The reflectance of those two wavelengths was transformed to relative absorbance depth to minimize the influencing factors. The results indicate there existing strong linear correlation between soil moisture and relative absorption depth for different soils. Independent data sets were used to validate the calibration model, and the root mean square error is less than 6% except for the red soil from southern China. The research shows the adaptability of the sensor for different soils and the calibration steps.

Abstract:By using a laser profiler, the roughness of ploughed soil surface was obtained. 3D fractal interpolation method was used to interpolate several kinds of reduced measured surface data which were reduced from the original measured ploughed soil surface elevation data in different reduction rates. Also fractal and statistical characteristic parameters were used to compare the original data and the interpolated data. The results show that 3D ploughed soil surface model can be obtained efficiently by the 3D fractal interpolation method with the reduction rate below 80% and the fractal non scale spacing of the dimensions was deduced: the transverse and longitudinal spacing were 23mm and 459mm, respectively. The result provided a theory for choosing the minimum measurement spacing of the ploughed soil and a method for reconstruction of ploughed soil surface.

Abstract:Life cycle assessment of biodiesel produced from microalgae showed that the pure energy output was negative by the route of biodiesel (FAME), if the biodiesel was produced from high moisture content microalgae slurry by dry, cell disruption, solvent extraction of lipids, and transesterification. Therefore, passive choices are that mathane or bioethanol is obtained by anerobic digestion of microalgae slurry or their hydrolysate, or microalgae based bio-oils are obtained by fast pyrolysis and microwave assisted pyrolysis of dried microalgae biomass, or microalgae based bio-oils or syngas by hydrothermal treatment of microalgae slurry. Although the high heating value（HHV）of microalgae based bio-oils are much higher than lignocellulosic bio-oils, it can still not meet the demand of transportation liquid fuel due to its high nitrogen content, high oxygen content and instability. Possessing superiority of dehydration, oil extraction, protein and polysaccharide separation, or even in situ biodiesel production from high moisture content microalgae slurry, subcritical water treatment may become the prior research field of downstream processing technology for microalgae biofuels today. The most challenging research field is to know how to extract lipids, separate cytochrome, protein, polysaccharide from high moisture content microalgae slurry simultaneously under very mild reaction condition of enzymolysis, so that most of the functional components of the microalgae will be saved for value added comprehensive utilization. Last and key technology that may guide microalgae fuel to commercialization is how to manufacture renewable and high quality hydrocarbon diesel effectively from microalgae oil or its soap by microwave polarization decarboxylation.

Abstract:In order to improve the performance of saccharification of Jerusalem artichoke stalk in bioethanol production, the hydrothermal pretreatment of stalk with H2SO3 catalysis and high-substrate consistency enzymatic hydrolysis were performed. Based on this work, the suitable pretreatment conditions, the high substrate consistency potential and the enzymes input lowering potential were determined. The results indicate that the suitable pretreatment should be carried out at 180℃ with 2% H2SO3 catalysis, by which the hemicellulose in stalk could be completely removed. Consequently, the maximum hydrolysis ratio of 90.0% could be achieved with 2.0% substrate consistency, 20FPU/g cellulose loading and 40CBU/g cellobiase loading. The high substrate consistency potential of pretreated Jerusalem artichoke stalk was suggested as 12% for enzymatic hydrolysis. The cellulase and the cellobiase input at this consistency could be lowered to 15FPU/g and 20CBU/g, by which the hydrolysis ratio of 88.3% could be achieved, with only 1.8% decrease compared with the maximum hydrolysis ratio. Correspondingly, the cellulase and the cellobiase loading is reduced by 25% and 50%, respectively.

Abstract:Shii-take cultivation waste (SCW) was used as rich carbon material for anaerobic digestion under the mesospheric condition as (35±1)℃. Orthogonal test and regression analysis L9(33) were employed to determine the effects of the three factors including pretreatment period, inoculums concentration and total solids (TS) on biogas production. The optimal combination of the three factors has been achieved. The high-carbon content material was proved to be not an ideal feedstock for biogas production. However, after a certain period of pretreatment, the high carbon feedstock biogas production was improved a lot. The biogas production reached to 0.16L/g(TS), increased by 128.57% compared with the control sample. The sequence of factors effecting SCW anaerobic fermentation is pretreatment period (evident), TS (evident), and inoculums concentration (less evident). A multiple regression equation was established and can be used for biogas production prediction under different conditions.

Abstract:The flow fields in cyclone at various model gases with ρ=0.6125~2.4500kg/m3 and μ=4.4735×10-6~4.4735×10-5kg/(m〖DK〗·s) were simulated by the computational fluid dynamics (CFD) software package, FLUENT 6.3. The influences of density and viscosity of gases on the dimensionless tangential velocity and pressure drop were performed respectively by single factor analysis. The result indicated that the dimensionless tangential velocity of gas flow in cyclone increases as the viscosity increase, while decreases with the increase of viscosity. Both density and viscosity have logarithmic function relations with the dimensionless maximum tangential velocity. The drag coefficient is not only influenced by the geometric parameters of the cyclone, but also affected by the viscosity of gases; there is a logarithmic regression between the pressure drop and viscosity of gas. Moreover, a fitting bivariate polynomial equation between the dimensionless tangential velocity and the factors was obtained.

Abstract:The blade dynamic stall behavior of a vertical axis wind turbine with high height to radius ratio was studied using a numerical method. The numerical modeling technique reliability was validated through a comparison of the computational results with the wind tunnel measurement. Below constant wind condition 8m/s, combined with the velocity vector and vorticity contours, the dynamic stall behavior and the rotor power performance were investigated with different tip speed ratios and variant turbine configurations. Illustrated by the simulation, lowering the tip speed ratio and increasing the rotor cord to radius ratio and the blade number will enhance the vortex generation and the flow separation on blades, leading to significant degradation of turbine performance. It can be concluded from the numerical analysis, a vertical axis wind turbine with high height to radius ratio applied in urban area will experience a better performance when operating in the optimal tip speed ratio, with rotor cord to radius ratio between 0.2 and 0.4, and 3 or 4 blades.

Abstract:The technology of swirling combustion and a new kind of wood briquette fuel swirling burner were proposed to improve thermal efficiency and reduce pollution emissions of the wood briquette heating stove. Numerical simulation on combustion processing of different excess air coefficient and different inclination between the secondary air inlet and grate wall in the heating stove was considered, aiming to solve the velocity, temperature and concentration field. The results reveal that high temperature backflow zone coming out through rotational flow secondary wind effectively strengthened combustion and improved the furnace using area; combustion efficiency is the highest and pollution is the lowest, when excess air coefficient is 1.5 and inclination angle is 30°.

Abstract:In order to improve energy efficiency and to relieve shortage of fossil energy and environmental problems, a biogas combined cooling heating and power (CCHP) system driven by internal combustion engine was designed, and its energy flow was presented. As a case study, the biogas CCHP system for a hotel in Beijing, about 10000m2, was analyzed and compared in two operation modes: following the electrical loads (FEL) and following the thermal loads (FTL). The equipment configuration, fuel consumption and supplementary power and the energy, economic and emission performances were calculated and compared in the two operation modes. The results indicate that the primary energy rate (PER) of the CCHP system in FEL is 4.3% higher than in FTL; the investment payback period is 1.4 years shorter; and the CO2 emission reduction is 254.9t less. The biogas CCHP system in FTL has more environmental benefit and in FEL is more efficient and economical.

Abstract:The experiments of pressure shift freezing (PSF) and conventional freezing were conducted on beef, and the thermal behaviors and ice crystal properties in freezing process were analyzed. The PSF experiments at 100MPa (-9℃), 150MPa (-15℃) and 200MPa (-20℃) were performed as well as conventional air freezing (CAF) and liquid immersion freezing (LIF) at -20℃ and 0.1MPa. The results show that most of the ice crystals formed in conventional freezing is extracellular, the size is large and non uniform, and severe strain and mechanical injuries has happened on the tissue cells. The crystals formed in PSF have smaller and more uniform size and spread more evenly in samples than that in conventional freezing. And the higher the pressure was, the more crystals formed in intracellular spaces and the less cell injuries happened. The freezing time in CAF is 85min, in LIF is 5.5min, and is 2.47, 1.22 and 0.83min when subjecting to 100, 150 and 200MPa PSF treatments; the degree of supercooling formed in depressurization increases with pressure increasing. However, the freezing point drops with and the freezing time needed reduces with the pressure increasing.

Abstract:In order to develop the design method of automatic orientation of eggs according to the pointed end and the blunt end, the mechanism of turnover motion of eggs on the convey rollers was analyzed and verified under the conditions of different verities of eggs and different diameter, center distance of convey rollers. Results show that the turnover motion of eggs on convey rollers was accordance with the principle of the cam. The transmission model of the egg, convey rollers and guide rod was built; and theoretical calculation method of the rolling distance of egg and the action distance of guide rod were developed. The design and calculation methods of the processing aisle width and bending length of guide rod were also proposed. The results of theoretical calculation were consistent with the test results. The rolling distance of egg and the action distance of guide rod had a positive liner correlation with the center distance of convey rollers and had a positive liner correlation with the diameter of convey rollers. The determination coefficients were all above 0.94. It is feasible and correct to use principle of the cam to analysis the mechanism of turnover motion of eggs on convey rollers.

Abstract:Measurement of freezing point temperature for living tissue of fruits and vegetables plays an important role for study on chilling, freezing injury mechanism and freezing process of fruits and vegetables. The freezing point temperature obtained by traditional measurement methods is difficult to be used to direct industrial process, because the temperature is from fruit and vegetable juice temperature, has great difference with the freezing point of living tissue, and is greatly influenced by the shapes and sizes of fruits and vegetables by putting the thermocouple or thermal resistor into fruit and vegetable tissues. The measurement system for freezing point of living tissue of fruits and vegetables was developed based on one dimension unsteady state semi-infinity heat conduction theory. The results show clearly that this measurement is convenient and reliable for determining freezing point of living tissue of fruits and vegetables. It is convenient, time saving, samples saving and environment thermal disturbance less. It has a good application prospect in determining freezing point of fruits and vegetables.

Abstract:Collagen was extracted from pollock bones and hydrolyzed with trypsin. An enzymatic hydrolysis prediction model of pollock bone collagen was established based on artificial neural network. It shows that the viscosity of collagen and its hydrolysates is decreased with the increasing of temperature. With the hydrolysis degree increasing, the peptide chain length, the molecular weight decrease, and the intrinsic viscosity decrease. In addition, it exhibited a one to one mapping relationship between the hydrolysis degree and the intrinsic viscosity. Using the intrinsic viscosity and the temperature as input parameters and the degree of hydrolysis as output parameter, a neural network was trained and simulated by 51 samples. The value of R2 is 0.9916 and the average relative error is only 2.5%, which indicates a good relevance between the sample actual value and the simulation value. Then three verification tests were performed using the prediction model, and the theoretical value is in agreement with the experimental value. The relative error is in range of 1.06%~4.32%. Therefore, the model can predict and monitor the hydrolysis of pollock bone collagen.

Abstract:Heavy mental ionsin plants always have complex chelation with the organic molecular groups that have the near-infrared spectral (NIRS) absorptions. Therefore heavy mental ions in plants can be indirectly detected by using INRS technique basing on the chelation. An application of near infrared spectral technology fast detecting heavy metal lead (Pb) in vetiver grass leaves was analyzed. Combined with partial least squares (PLS), different preprocessing methods including smoothness, standard normal variate, baseline correction, multiplicative scatter correction, first derivative and second derivative were compared, model parameters were optimized by different wavelength selection methods including genetic algorithm, interval partial least square and successive projections algorithm, established the fast detection models of heavy metal Pb in vetiver grass leaves. The results showed that the external validation determination coefficient (R2) and root mean square error of prediction (RMSEP) was 0.87 and 0.18 separately. The study shows that the fast detection of heavy metal Pb in vetiver grass leaves using INRS technique is feasible.

Abstract:Automation and industrialization is the trend of pig industry. Real time detection of parturition is one of the key technologies of sow automation farming. Video image features of sows parturition were analyzed to detect sows parturition by recognizing piglet. The moving objects were detected based on the improved single Gaussian model. Disturbance of sow moving was removed by the arithmetic of matching semi circle. According to the color and size characteristics of newborn piglets, targets were recognized. Test results showed that the sow object could be recognized effectively by the proposed approach. The moving objects detection method based on the improved single Gaussian model detected the slow moving piglet completely after eliminate interference.

Abstract:In order to improve the detection sensitivity of brucella antibody and discover diseased livestock earlier for reducing economic losses, a disposable label-free immunosensor for rapid and quantitative detection was prepared. It was made by modification of cysteamine onto screen printed gold electrode surface and immobilization of antigens. By the method of cyclic voltammetry, it was shown that there is a linear relationship between the changes of peak current and the different brucella antibody concentrations within the range of 10-5~10-3IU/mL, the relevant correlation coefficient is 0.9999 and the lower detection limit is 2.8×10-5IU/mL. Furthermore, semi-differential transformation was applied to all of the cyclic voltammograms, the correlation between the changes of semi-differential values and the corresponding concentration of brucella antibody has been established, the correlation coefficient is 0.9929 and the lower detection limit is 2.7×10-6IU/mL in the range of 10-5~10-3IU/mL, and the correlation coefficient is 0.9992 in the range of 10-2~1IU/mL. It was shown that the detection range and the lower detection limit were improved greatly by the semi-differential transformation.

Abstract:A method for visual simulating leaf color based on the relative content of chlorophyll was proposed. The mathematical model between cucumber leaf color components and chlorophyll relative content was established according to images acquisited from real field and measuring chlorophyll relative content (SPAD) of the cucumber leaf in normal growth state continuously, and the model was also verified by using root-mean-square error (RMSE). The results showed that the RMSE between the observed values (R, G, B) and simulated vales(R, G, B) in leaf are 13.43%, 8.47%, 7.42% respectively. The rendering for the spatial distribution of apparent color of cucumber leaf was realized by combining with a black and white pigment distribution texture which was a grayscale image before being preprocessed. Then the high level shader language (OpenGL 2.0 Shader Language) was used to realize the rendering of apparent color changing process of cucumber leaf. The above process showed that the method proposed can achieve better realistic rendering results.

Abstract:Taking Fujian province as the research object and basing on the CCD data of HJ-1, four vegetation indices were selected which closely related to LAI. The selected indices included NDVI, RVI, mSAVI and EVI. Meanwhile, data synchronized with LAI of Pinus massoniana was obtained, and then the relationship between the indices and the LAI was built. At last, six kinds of the non linear regression models, between the LAI of Pinus massoniana and the selected index RVI that most closely related to the LAI, was established. It was found that the model based on the Richards distribution function is the best and the relative error of the prediction of mean value is 3.1%. Based on this model, the remote sensing inversion of the LAI of Pinus massoniana in Fujian province was implemented.

Abstract:The investigation proposed a new algorithm to automatize the identification process of pests and insects disease of Citrus reticulata Blanco var. Ponkan, in which multi-fractal spectra of image hue were set as inputs of wavelet neural network model. In the new algorithm, image boundary of damage pattern of Ponkan was extracted with improved watershed algorithm, and discontinuous boundary was processed with boundary following, meanwhile over-segmentation region was merged and boundary was marked, at last, damage pattern image was generated. After the work above, firstly, hue range 0°~120° of damage pattern image was equally segmented into 4 regions to generate 4 binary images. And then these binary images were analyzed by multi-fractal method to calculate the widths and heights of multi-fractal spectra of scale invariance region. In the end, the widths and heights of multi-fractal spectra were set as the inputs of wavelet neural network model to identify the pest and insects disease of citrus fruit. Test results showed that the accurate rate of identification of 5 pests and insects disease is about 87%, which means that widths and heights of multi-fractal spectra are sufficient to characterize the damage pattern of citrus fruit, and this method is applicable in machine automatic recognition for pests and insects disease of citrus fruit.

Abstract:Focusing on the fusion problem of infrared and visible light images in the same scene, a novel multirsensor image fusion algorithm based on the non subsampled Shearlet transform was proposed. Firstly, the NSST was performed on the source images at different scales and directions, thus the low frequency subband coefficients and varieties of directional bandpass subband coefficients were obtained. Secondly, the low frequency subband coefficients of the fused image were selected based on the local structural similarity and local energy of the two source images, and the bandpass subband coefficients of the fused image were selected based on the firing times of the pulse coupled neural network(PCNN), so the NSST coefficients of fused image was got. Finally, the fused image was obtained by performing the inverse NSST on the combined coefficients. Quantitative and qualitative analysis of the experimental results demonstrated that the proposed method performs significantly better than the other five related methods.

Abstract:A novel weed recognition scheme based on fuzzy BP overall neural network is proposed. First, the classification features are blurred to deal with the uncertainty of weed features. Second, the genetic algorithm is used to optimize the network structure so as to improve the network’s convergence and stability. Finally, a feature-level data fusion scheme is used. In weed species identification experiments, neural network consists of the 4 BP sub-networks on color feature, main texture feature, secondary texture feature and spectral feature. The results indicate that the overall recognition rate reaches to a good recognition accuracy of 94.2% for 7 weed species. Besides, experiments were put into effect on the corn and its accompanying weeds. The neural network consists of the 4 BP sub-networks on color feature, main texture feature, height feature and spectral feature. The recognition rate reaches to 96.7% with a better recognition accuracy.

Abstract:Usually machine geometry precision design is preformed depending on human experience but not reference data form design theory. To learn numerical effect an approximate model of relationship between machine geometry precision and product machining precision is provided based on multibody theory. The analysis results by Monte Carlo sampling would deduce geometry precision of each axis in machine. Taking geometry precision design of spiral bevel gear milling machine as an example, the approximate model well explains effect of machine geometry error on gear product surface machining quality by explicit. Then geometry precision of each axis is obtained by mapping from tooth surface machining precision.

Abstract:The design method of real-time Ethernet EtherMAC master based on SMP architecture was proposed, while a field bus oriented motion control engine was developed, which was running in kernel space. To make the procedure of motion control program development easy, a cross-platform programming interface was created by making memory stack in a shared memory for transferring parameters. To reduce the coupling between the motion control engine and the field bus, and to enhance the adaptability of the engine to any other field bus, a bus abstraction layer was proposed and designed. The result from prototype shows that the motion control engine has a better ease of use and a better portability, and indirectly enhances the EtherMAC real-time performance.

Abstract:In order to meet the optoelectronic tracking requirements for a small size floating stabilized platform with small volume and high load inertia, an improved parallel mechanism based on deficient DOF parallel mechanism has been designed. The Jacobian matrix is derived, and the dynamic model has been established by using Lagrange method. Considering the internal coupling, uncertainties and disturbances of the system, a workspace based composite control with disturbance observer is proposed. The disturbance observer is used to observe the disturbance of the system and reduces the upper bound of the disturbance. Based on backstepping method, the sliding mode controller is designed for tracking and residual disturbance suppression. The simulation and experiment results show that the proposed model and method have made tracking error reduced to ±0.08° which is 14.5% of PID, and is suitable for parallel mechanism.

Abstract:The normal quaternion method of inverse kinematics of serial mechanisms has the limitation of lacking equations and is difficult to solve. In order to solve these problems and put forward a new method of inverse kinematics of serial mechanisms, a D-H quaternion method for inverse kinematics of serial mechanisms is proposed. The general equation of quaternion transformation including D-H parameters was given first. Two equations of position and posture were obtained by separating the general equation of quaternion transformation. By these two equations, an equation system with seven equations was constructed, which met the number requirement of the equations for inverse kinematics of serial mechanisms with more than four degrees of freedom. In order to lower the difficulty in solving equations, the degree of posture equation was reduced to half by taking half of the trigonometric function in the original posture equation to construct a new posture equation. By using the proposed D-H quaternion method, the inverse kinematics of PUMA robot was analyzed, and eight groups of inverse solutions were obtained. Three dimensional models of PUMA robot were established based on the eight groups of inverse solutions. Measured results of end positions and postures in the three dimensional models are consistent with the given values. The example of PUMA robot shows the correctness and validity of the proposed D-H quaternion method.

Abstract:The aim of this research is to explore the mechanism and the suppression methods of creeping phenomenon in hydraulic cylinder system. The nonlinear time-varying laws and function mechanism of hydraulic spring stiffness and friction were revealed through theory analysis. Then, with the nonlinear dynamics methods, the measured dynamic data were thoroughly analyzed. The “jump phenomenon” caused by the nonlinear time-varying characteristic of hydraulic spring stiffness and the “limit cycle oscillation” caused by the nonlinear time-varying characteristic of friction were revealed. The combined effect of nonlinear hydraulic spring force and nonlinear friction is the main cause for the low-speed creeping of hydraulic cylinder. Moreover, the corresponding suppression measures were proposed to improve the low-speed transmission stability of hydraulic cylinder. The results indicate that the research can make the comprehensive analysis of dynamic characteristics of hydraulic cylinder system more realistic.

Abstract:A simple method for forward displacement analysis of a kind of 5-5 in-parallel robot is presented, after its structural characteristic has been disclosed. First of all, the parallel robot was decomposed into three single-opened chains (SOCs). Secondly, the dimension of its kinematic equations was reduced to the minimum by considering kinematic model of the three single-opened chains. Then, all the real solutions to the kinematic equations were obtained using one-dimension searching algorithm. At last, a numerical example with 20 real solutions was given for the first time and provided to confirm the efficiency of the solution procedure.

Abstract:Two-dimensional high-frequency rotary valve is a kind of rotary valve designed by using spool with two degrees of freedom. When the spool rotates at a high speed, the velocity variation of fluid flowing through the valve ports generates periodic hydraulic torque on the spool, which imposes negative effects on the spool movement or even adversely affects the function of the valve. By calculating the flow fields in the chamber of 2D high-frequency rotary valve with different spool geometrical configurations, the influences of different geometrical dimensions on the average pressure and the average velocity around the notch walls and the flow moment imposed on the spool are presented. The results show that the structure and the layout of No.3 spool unit and No.4 are reasonable, and that the greater the spool groove bottom height h is, the more smoothly the hydraulic moment changes and the greater the flow rate through the valve port is.

Abstract:Aiming at the accurate fluid control and the miniaturization of piezoelectric pump system, a flow self-measurement method for single chamber and single vibrator piezoelectric pump was proposed based on piezoelectric self-sensing and neural network. A bimorph vibrator was applied in piezoelectric pump acting as actuator and sensor simultaneously. Firstly, the influencing factors of flow were analyzed using the pi theorem of hydromechanics. Secondly, the relationship between sensing piezoelectric signal and deformation of the vibrator was studied. Then, the information of flow implicit in the sensing piezoelectric signal was found. Thus, a prototype of the parameter measurement circuit for sensing piezoelectric signal was made, and a BP neural network model for flow prediction was constructed by using the parameters acquired from the circuit as the input vector. Experimental results show that the correlation coefficient between the predicted data and the measured data is above 0.9993, and the maximum relative error is less than 3.46%. the results of prediction are close to the actual data. The method proposed for flow self measurement has a good accuracy.

Abstract:By adopting the concepts of “rise and return travel” and “F/P type mechanism” and dividing the conjugate cam mechanism into main cam and assistant cam mechanism, which were studied respectively, the basic schematic diagram of instantaneous one dimensional linear area of the assistant cam (i.e. P type mechanism) and the curves of vC1-θ1、vC2-θ1 and uK-θ1 were proposed. And the differences between the main cam (i.e. F type mechanism) and the assistant cam (i.e. P type mechanism) were presented. The class Ⅱ synthesis of P type mechanism and conjugate cam mechanism with floating flat face pushrod was resolved.

Abstract:A simultaneous optical visualization experimental system was set up, and a parallel triangle silicon microchannel heat sink was used as the test section. Five platinum film microheaters was etched at the top glass cover surface and located at the microchannel entrance, acting as a seed bubble generator array. The microscale flow boiling instability under different seed bubble frequencies was experimental examined. The results show that the seed bubble frequency is an important parameter to control flow boiling instability. In the single liquid flow region, seed bubbles have negligible effect on flow. In the two-phase flow region, with heat flux increasing, pressure drop increases linearly and the temperature of the heating wall surface increases exponentially. Moreover, higher pressure drop could be approached with lower wall temperatures and higher bubble triggering frequency. With the same heat flux, the seed bubbles triggered with high frequency can completely eliminate flow boiling instabilities, heating wall temperature could be dramatically decreased, and the uniformity of the temperature could be promoted significantly.