Abstract:Cycle fuel injection quantity fluctuation of electronic unit pump (EUP) determines the coherence and stability of the EUP fuel injection system. The simulation model of EUP was established in the AMESim environment, and the method of simulation experiment was designed by using the design of experiments (DOE) method. The result obtained by the simulation revealed the variation law of correlation under parameters interaction or not respectively in the overall operating conditions. The result shows that the EUP system is a complex nonlinear system. In the overall operating conditions the characteristic parameters such as fuel supply pressure, cam profile velocity, control valve lift, injector opening pressure, and injector needle lift as well as the injector flow coefficient have remarkable correlation with the cycle fuel injection quantity when there is no interaction between parameters. The second order factors under self interaction of parameters are the most remarkable second order factors when the interaction between parameters is considered.

Abstract:The driving mode of Peak & Hold current shape is adopted in common rail diesel electronic control injector driving circuit. The requirements of current change are different in different stages. In order to meet the changes in the injection process, the state responses characteristics of the circuits to optimize the circuit and improve the response speed of electronic valve were analyzed theoretically. The driving circuit was designed based on the bootstrap circuit. The results showed that the fluctuations amplitude of the current in the hold stage reduced by 50% under the same driving parameters in the optimized circuit, and the response time was only 20μs in the injector closing process, which realized the purpose of precise control of the injection quantity and injection timing.

Abstract:In order to quickly calibrate SCR controller, space-falling experiment design was applied to get 130 optimization operation points while developing SCR system for a type of diesel engine, which reduced the experimental workload for two-thirds. The target diesel engine emission model and SCR catalyst model were developed by using neural network based on diesel emission characteristic experimental database and catalyst characteristic experimental database. Multi-objective optimization arithmetic was applied to gain urea dosing map based on SCR catalyst model. ESC (Europe steady cycle) experiment validated that the precision of urea dosing map satisfied the requirement of SCR control.

Abstract:An experiment was carried out on a four-cylinder spark-ignited (SI) gasoline engine to investigate the effect of hydrogen addition on the engine performance at low idle speed conditions. The engine was run at three idle speeds of 800r/min, 700r/min and 600r/min. At the specified idle speed and stoichiometric conditions, the hydrogen volumetric fraction in the total intake was gradually increased from 0 to about 6%. The experimental results showed that the engine fuel energy flow rate was reduced from 30.8MJ/h at the idle speed of 800r/min and a hydrogen volumetric fraction in the intake of 0 to 18.6MJ/h at the idle speed of 600r/min and a hydrogen volumetric fraction in the intake of 6.0%. For different idle speeds, the engine combustion duration was shortened, cyclic variation was eased and HC, CO and NOx emissions were decreased with the increase of hydrogen volumetric fraction in the intake. All in all, the addition of hydrogen was effective for enhancing the engine performance at low idle speed conditions.

Abstract:In order to make better use of waste heat energy from engine exhaust gas, the waste heat recovery system based on organic Rankine cycle (ORC) was presented, a single screw expander was used as the power output device, R245fa was used as working fluid, the concept and calculating method of waste heat recovery utilization rate was introduced. On the basis of engine test results, the effects of working fluid evaporating pressure and engine speed on the ORC system performance were analyzed and discussed, and then the optimal value of working fluid evaporating pressure was selected. According to the research results, when the working fluid evaporating pressure is 3.0MPa, ORC waste heat recovery system can work properly over the whole range of engine speed, the maximum of net power is 12.1kW, the maximum of first law efficiency is 11.27%, the maximum of second law efficiency is 25.8%, the maximum of waste heat recovery utilization rate is 8.9%, waste heat energy from engine exhaust gas can be recovered effectively.

Abstract:Considering the regulating and structural characteristics of electric-hydraulic speed governor, an optimization study on elastic connecting plates was conducted. Firstly, on the basis of accurate force analysis, static analysis was done for the initial design of connecting plates by using the finite element method. Then, the mathematical model of the optimization design was established, which took several geometrical dimensions near the connecting plate’s middle rabbets as design variables, larger deformation displacement of the middle part as the optimization objective, and high reliability and good response as the constraint condition. Finally, an optimization analysis was carried out for different configurations by using COSMOSWorks/OPTSTAR, the actual working condition of the connecting plate was simulated and the calculation precision of the finite element method was verified through the experiments. The analysis of the result revealed that after optimization, the connecting plate increased Z-axial deformation displacement of the connecting plate, which can effectively improve the plate’s regulating sensitivity and reliability in the system.

Abstract:Relationship between spatial variability of soil water content, soil electrical conductivity, sand content, clay content, slit content, fractal dimension of soil particle-size distribution, bulk density and organic matter content in 0~20cm soil layer and their spatial variabilty in 20~40cm soil layer at multiple scale was studied with joint multifractal. The results showed that changing ration for spatial variability of slit content and organic matter content was the largest, the one for spatial variability of soil electrical conductivity, clay content and fractal dimension of soil particle-size distribution was the least, and the one for spatial variability of sand content, soil water content and bulk density lay between the two in 20~40cm soil layer compared with spatial variability of corresponding variables in 0~20cm soil layer; at multiple scale, relationship between spatial variability of soil water content, bulk density, organic matter content, clay content, sand content, soil electrical conductivity, fractal dimension of soil particle size distribution and slit content in 0~20cm soil layer and corresponding soil properties in 20~40cm soil layer decreased gradually.

Abstract:Monofractal and multifractal analysis were combined to quantitatively investigate soil particle size distribution (PSD) in hilly and gully areas of the Loess Plateau, and the effect of land uses on PSD parameters was analyzed. The results indicated that the PSD showed heterogeneous distribution, had multifractal feature, and multifractal spectrum functions f(α)-α were asymmetrical convex curve. There was no significant relationship between capacity dimension (D0) and soil particle contents. Clay contents were positively correlated with the entropy dimension (D1), correlation dimension (D2) and the width of multifractal spectra Δα(P<0.01). The clay contents, silt contents, sand contents and dimension of silt domain (Dsilt) values were significantly influenced by land uses (P<0.01). The multifractal analysis provided an accurate method to characterize the PSD.

Abstract:The relationship between the fractal dimension for soil water retention curve of the disturbed and undisturbed soil was studied in greenhouse soil. It was showed that on the condition of the same soil texture, fractal dimensions increased with the increasing of soil bulk density. There was significant linear relationship between the fractal dimension of the disturbed soil and that of the undisturbed soil. Based on the fractal dimension of soil weight distribution and soil water retention curve of Brook-Corey model, water retention curves of the disturbed and undisturbed soil were predicted. The results show that the predicted values of soil water retention curves fit the measured data. So, it is feasible to estimate soil water retention curve of the undisturbed soil based on the fractal dimension of the disturbed soil in the greenhouse soil.

Abstract:Take the drought remote sensing for winter wheat in He’nan province as an example, the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), leaf area index (LAI) and land surface temperature (ST) data from MODIS/AQUA were applied to analyze NDVI—ST space and EVI—ST space. It was discovered that NDVI—ST and EVI—ST spaces were double parabola as compared with NDVI—ST, EVI—ST and LAI—ST triangle or trapezoidal space. The relationship between TVDI and soil moisture was analyzed with the obtained TVDI derived from the spaces. The results show that the NDVI—ST double parabola space is better than the others to reflect the 10cm-depth soil moisture. Based on the TVDI obtained from the NDVI-ST double parabola space, the drought situation in He’nan province, from February 26, 2011 to May 16, 2011 was evaluated. Compared with the raining data observed by local weather stations, the general spatio-temporal features of the drought situation of winter wheat in He’nan in the spring of 2011 was revealed.

Abstract:CFD was used to study the mechanism of the performance curve instability of the mixed flow pump with vane diffuser characterized by the positive slop of the head-flow curve. The two parts of performance curve instability including the dramatically head drop and a slightly rise of the head when the flow rates decreased further. The reason of the two parts was that the decreasing of the effective diameter of the impeller blade TE was caused by the appearance of the vortices in the tip of the impeller outlet which was caused by the reverse flow. The flow separation and the flow pattern of the tested pump shifted to the centrifugal pump which led to the strong vortices in the impeller hub respectively and it was got by steady simulation. The unsteady simulation was used to study the reason of reverse at hub of impeller outlet and it was found that the stall is the main reason for the mixed flow pump shifting to the centrifugal pump. It was also found that asymmetry of pressure at vane inlet is the main reason of the stall for its propagation.

Abstract:In order to avoid the disadvantages of cumbersome, error-prone, long cycle of shaft strength calculation by traditional method, a multi-stage centrifugal pump shaft strength calculation program was developed based on parametric design language APDL. By transferring script file of the self model program and executing the command SOLVE to calculate, parametric automatic modeling, load application and solution, and the results of 3-D parametric display under zero-flow conditions and design point conditions were realized. The stress distribution of the shaft at different conditions on different sections and dangerous position were clearly described, and the accurate calculation of the shaft strength can be performed. Application examples showed that the design and development application program was used friendly and can get accurate calculations with visual results. This program of shaft strength calculation greatly improved the computational efficiency of shaft strength and reduced the analysis cost.

Abstract:The flow section area was controlled by increasing thickness of centrifugal impeller blade, so as to realize the non-overload characteristics of low specific speed sewage pump. It was shown from the external characteristic experimental results of prototype when the flow section area changed gently, the extreme point of shaft power curve appeared, and the units showed an obvious non-overload performance after the flow rate attained to 1.5 times of the designed flow. The experiments and prediction were also conducted to the section which perpendicular to the axis and passing by neutral position of impeller outlet. The experimental results showed that under the designed working conditions, the external characteristic experimental results were not only consistent with the computational results, but the PIV experimental data also had very good agreement with the internal flow field computation. At the same time, in the impeller channel, the relative velocity of pressure side was less than suction side due to the Coriolis effect, the flow field distributed uniformity with no obvious flow separation and vortex. The flow of each impeller channel was not in absolutely axial symmetrical distribution because of the rotor stator interaction between the impeller and volute.

Abstract:In order to research the relationship between the size of impeller cutting of super-low specific speed centrifugal pump and the changing pump performance, centrifugal pump IS 50—32—250 was chosen as the research object. By using commercial software Fluent to conduct numerical simulation of three-dimensional flow field, the distributions of pressure and velocity in the impellers and pump bodies under different impeller diameters were calculated. By comparison of calculated results of different diameters, the influence of the size of impeller cutting on pump performance was obtained: when the size of impeller cutting was 0.03, the efficiency raised suddenly; when the size of impeller cutting was 0.09, the efficiency decreased slightly; when the size of impeller cutting was 0.15, the efficiency sudden dropped dramatically. The size of impeller cutting could not be bigger than 0.15 in the practical application, otherwise, the performance of pump dropped dramatically.

Abstract:To solve subsequent treating problems of chicken farm biogas project slurry, a research was carried out on treatment processes of anaerobically digested effluent of chicken manure for meeting the discharging standard—a case study of treatment of CSTR fermentation tank effluent of a biogas project. Based on the characteristics of anaerobically digested effluent of chicken manure, bio-chemical treatment combined with physical-chemical process was used to treat the biogas slurry. In addition, effects of three different processes combination method were investigated. First, bench scale experiment was carried out to determine the optimal operation parameters, and then pilot scale devices were introduced to examine the effect of the process. Results showed when using struvite—SBR—coagulation process treating anaerobically digested effluent of chicken manure, CODCr decreased from 9200mg/L to 280mg/L, NH+4N decreased from 3200mg/L to 36mg/L, TP decreased from 270mg/L to 3.3mg/L, finally the effluent met the standard GB 18596—2001. To remove NH+4N in chicken manure slurry, pretreatment is essential. Because of inhibition of free ammonia to microorganism, NH+4N removal rate is less than 30% while using SBR directly treating chicken manure slurry. Biodegradability of anaerobically digested effluent of chicken manure is good, but the amount of refractory CODCr is considerable. Using bio-chemical treatment combined with physical-chemical advanced process can meet the discharging standard with lower cost.

Abstract:The development process of air biomass gasification in a down-draft fixed bed gasifier was analyzed by using multi-dimensional numerical simulation method firstly and was proved to be feasible by the experimental results. Then based on the research above, the influence of the equivalence ratio RER on the temperature distribution over the entire gasifier and gas composition of the biomass gasification were investigated and predicted by numerical simulation, respectively. The results indicate that RER has significant influence on the gasification characteristics and the best range of RER is 0.24～0.28.

Abstract:The LS—SVM (least square supporting vector machine) model of combined tar removal process in pine block gasification was established according to the experimental data. On the basis of condition optimizing for tar removal in the furnace, multi-objective optimization function for catalytic activity was put forward, and then the Pareto-optimal solutions were gained after optimization. The results showed that the tar content from gasifier outlet was less than 2g/m3, which met the requirements of inlet tar content for catalytic cracker. The tar content at the entrance of tar catalytic cracker was between 0.126g/m3 and 0.340g/m3.The gas heating value was more than 4MJ/m3, met the engineering requirements, so after condition optimization, the gas quality is better than that of the experimental results.

Abstract:Desorption and adsorption isotherms of macadamia nut shell at 25℃ were determined. Non-linear regression analysis was used to evaluate the fitness of the six commonly used models based on the experimental data, and to determine the best models and their parameters. The results showed that the obtained desorption and adsorption isotherms were of type Ⅰ, according to IUPAC’s classification. The hysteresis loop was of type H3. GAB model was the best fitted for desorption and adsorption isotherms. The parameters A, B and C of GAB model for desorption isotherm were 9.693, 0.605 and 8.378 respectively, and those for adsorption isotherm were 9.695, 0.635 and 3.268. The results provided fundamental data for macadamia nut preservation and processing.

Abstract:In order to explore the effective technique of extending storage period and improving commodity value in Mopan persimmon, effects of 1-MCP treatment and freezing point storage on fruit storage quality, senescence and browning indexes were studied. Results showed that 1-MCP combined with controlled freezing point storage effectively delayed the losses of fruit firmness, vitamin C, total soluble solids, titratable acidity and soluble tannin content, better kept fruit intrinsical nutrition constituents, restrained the rise of MDA, membrance relative conductance and PPO activity during later storage period, fruit senescence process and the occurrence of fruit browning were delayed, and the storage period was extended by about 60d compared with the control group. Therefore, 1-MCP combined with controlled freezing point storage is an effective integrated freshness-keeping technique for extending storage life.

Abstract:Effects of different concentrations of 1-MCP on freshness of harvested Younai (Prunus salicina Lindl. cv. Younai）fruits were investigated. The harvested fruits were treated with 0, 0.3, 0.6, 0.9, 1.2μL/L 1-MCP for 12h, respectively, and then stored at （25±1）℃. During storage, the changes of respiration rate and cell membrane relative leakage rate of fruits, hue angle（h°）value of fruit surface, content of pericarp chlorophyll, fruit firmness, contents of total soluble solids and titratable acid of fruit, healthy fruit percentage, weight loss and organoleptic evaluation of quality of fruit were determined. The results showed that compared with the control fruits, the treatments with 1-MCP lowered respiration rate and respiratory peak, delayed the increase of cell membrane relative leakage rate , inhibited the decrease of hue angle（h°）value of fruit surface, kept higher fruit firmness, and kept higher contents of titratable acid in fruit and chlorophyll in pericarp, retarded the change of apparent color of fruit, and decreased fruit weight loss and fruit decay. Among the 1-MCP treated ones, the fruits treated with 1.2μL/L 1-MCP could keep best fruit quality. After storage at（25±1）℃ for 20d, the fruits still maintained fresh green with 87% as healthy fruit percentage, crisp and hard flesh, properly sour-sweet taste and rich aroma. It can be concluded that treatment with 1.2μL/L 1-MCP for 12h can be used as the optimum condition for maintaining fruit quality and prolonging storage life of Younai fruits during storage at (25±1)℃.

Abstract:The plant resources with inhibitory effect on postharvest pathogenic fungi from citrus fruits were screened so as to provide the theoretical basis for the development of botanical fungicide. The experiments investigated inhibitory effects in vitro with 30 kinds of ethanol extracts from Chinese herbs against P. italicum,P. digitatum and Alternaria. Citri by using mycelial growth rate method, and control effects in vivo and storage effects of Valencia orange with Coptis chinensis ethanol extracts. The results showed that 30 kinds of Chinese herbs ethanol extracts have different effects on mycelial growth of three citrus pathogens, and Coptis chinensis ethanol extracts exhibited the best antifungal effect which reached up to 100%. However, no difference was found between Prochloraz treatment and Coptis chinensis treatment （P>0.05). Minimum inhibitory concentration (MIC) of Coptis chinensis ethanol extracts is 0.025g/mL.Control test showed that the control effect of Coptis chinensis ethanol extracts against the mixtures of three kinds of spores achieved 90.87% after 10 d of treatment, and there was no significant difference（P>0.05) between Coptis chinensis treatment and Prochloraz treatment. Preservation test indicated that Coptis chinensis ethanol extracts could obviously decrease the incidence of rotting rate and molding of Valencia orange fruits, increase the good fruit rate, and retard the losses of titratable acidity and vitamin C in fruits. Compared with Prochloraz treatment, there was no difference （P>0.05). These results indicated that in vitro experiments, control effect and preservation test exhibited a good antifungal effect with Coptis chinensis ethanol extracts. Therefore,Coptis chinensis ethanol extracts may have a possibility to replace chemical fungicides and a new pesticide can be developed.

Abstract:The objective was to investigate the effects of puffing initial moisture content and vacuum drying temperatures on the characteristics of apple slices dried by explosion puffing drying at variable temperatures and pressure difference. The drying kinetics model of explosion puffing drying at variable drying conditions was obtained. Results showed that the drying process of explosion puffing drying at variable temperatures and pressure difference obviously existed increase-rate, constant-rate and falling-rate period. Page model provided better simulation of drying curves for apple slices at different puffing drying conditions. The effective moisture diffusivity of apple slices dried by explosion puffing drying at variable temperatures and pressure difference was among 1.52×10-9～8.87×10-9m2/s. The established model can predict the moisture content change during explosion puffing drying time. Fitting undetermined coefficients k and n of Page model were linear with puffing initial moisture content and vacuum drying temperature. The coefficients of correlation r2 were 0.845 and 0.997, respectively.

Abstract:Taking wet towels as the research object, a far-infrared-assisted heat pump dryer was designed and manufactured. Wet towels were dried by using a heat pump (HP) dryer combined with far-infrared radiation (FIR) with the power of 500, 1000 and 2000W. Changes of drying chamber inlet air temperature, outlet air temperature, inlet air humidity, outlet air humidity, inlet sample temperature, middle sample temperature and outlet sample temperature were all studied. The experiments were conducted under pump drying and far-infrared-assisted drying with different powers. The results showed that compared with the pump drying treatment, the dehumidification capacity was improved effectively, with values of 8.1% to 22.2%. The present data suggested that far-infrared-assisted heat pump drying could shorten the drying time, improve the drying efficiency.

Abstract:After dried by the hot-air dying, the vacuum drying and the vacuum freezing drying, the area shrinkage percentage of North Cordyceps was analyzed by the digital image processing technology, and combined the shearing and the crushing mechanic characteristics, the suitable drying technology was chosen. Considering the powder quantity percent passing through the 200 mesh standard sieve, the processing of the shearing method and the ball milling method were investigated, the optimal processing parameters of the dried North Cordyceps were confirmed. The results show that the area shrinkage percentage, the shearing stress and the crushing stress of the freeze-dried North Cordyceps are the smallest, so the vacuum freeze drying technology is chosen as the suitable drying treatment method. The optimal processing parameters of the shearing grinding are as follows: the grinding time is 3 min, the material filling rate is 25%, the material moisture content is 3%, under these conditions, the grinding efficiency is 68.5g/h, the energy consumption is 0.46kW·h/kg. The optimal ball milling parameters are as follows: the milling speed is 266r/min, the milling time is 60min, the medium filling rate is 23%, the material filling rate is 15%, under these conditions, the grinding efficiency is 36.5g/h, the energy consumption is 2kW·h/kg.

Abstract:In order to establish predicting models for beef marbling grade, one hundred and thirty-five beef rib-eye samples were collected from a beef processing factory. A three-grader panel was employed to assign each sample a marbling score according to the official standard cards. Then images of each sample were captured with a CCD camera. The beef marbling images were separated and the indicators such as ratio of fat area, the total number of fat particles and numbers of the big and the small fat particles were obtained by using image processing technologies. After fractal dimensions of marbling images was calculated through the varying megascopic degree method, a multiple linear regression model and a multiple polynomial model for the prediction of marbling score were derived based on the obtained fractal dimensions and image feature parameters. Validation results showed that the correct percentage of the marbling grade predicted by the multiple linear model and by the multiple polynomial model were 75% and 87.5%, respectively, indicating that beef marbling grades can be determined by using fractal dimension and image processing method.

Abstract:Rapid detection the content of chlorophyll a, chlorophyll b, β-carotene and lutein on fresh cucumber leaves by using hyper spectral image and high performance liquid chromatography (HPLC) was done. One hundred and twenty hyper-spectral images of cucumber leaves were collected by near infrared hyper-spectral camera, then using HPLC to accurate detect the content of chlorophyll a, chlorophyll b, β-carotene and lutein. After hyper-spectral images have been corrected, a 50×50 pixels region as region of interest (ROI) was defined. Average spectrum from ROI was extracted and prediction model of partial least squares (PLS) with the content of four pigments was built. In order to advance the stability and prediction accuracy, interval partial least squares(iPLS) , backwards interval partial least squares(BiPLS) and synergy interval partial least squares(SiPLS) algorithm was used to select diagnostic bands of each pigments after optimized the number of spectrum interval. The result showed that using BiPLS and SiPLS would get the best PLS model, the best prediction coefficient of chlorophyll a, chlorophyll b, β-carotene and lutein is 0.8257, 0.8134, 0.8116 and 0.8262, respectively.

Abstract:In view of complex background of lesion images and the difficulty in segmentation, an improved C—V model based on level set and weighted color information was proposed and applied into agricultural lesion image segmentation. The segmentation model of weighted color information based on level set was suitable to different diseases identification and could identify lesion disease automatically. Experimental results show that the proposed model has better property than C—V model, and has many advantages such as anti-noise and scalability properties on 4R—G image model for cucumber pink and 3R—G—B image model for apple rust disease.

Abstract:Aiming at the ambiguity and uncertainty between nutrient deficiency and color characteristic of plant canopy image, a classification decision model based on regularized adaptive fuzzy neural network was set up to diagnose plant nutrition by using the complete rules of inference of fuzzy logic and adaptive of neural network. The “if-then” rules was fully used by the model, and the adaptive selection of law-level nodes and back propagation learning algorithm were given, meanwhile, network inference construction was perfected. The result of diagnosing soybean nutrient deficiency showed that the accuracy can be reach to 100%, meanwhile, the model has many advantages such as fast speed, stable, high precision, good robustness, as well as good adaptability and practical applicability.

Abstract:Camera calibration, image acquisition, stereo rectification, stereo match and depth calculation were developed to research a detection method of various obstacles in farmland by using the methods such as Bouguet algorithm, area match, and triangulation and so on. As a result, five different obstacles and their position information in different environments were got, and open computer vision library OpenCV was used to improve the real time property. The experiment showed that the accuracy rate of the obstacle detection reached 96% and the absolute error of depth was maintained within ±30mm (under 1.5% of the relative error) when the depth was less than 2000mm, and it takes less than 100ms to finish a obstacle detection.

Abstract:A kind of dynamic recognition method under the fruit oscillation condition for the harvesting robot was researched in order to resolve the problem of fruit oscillation influence to its recognition and orientation, and further influence to the harvest efficiency of harvesting robot. Firstly, the acquired oscillation fruit was segmented into two parts: fruit image and background image; secondly, the inter-frame difference method and the minimum enclosing rectangle method in horizontal direction were introduced to label dynamic region of the oscillation fruit for the segmented image; thirdly, the oscillation fruit was identified and located. The harvesting oscillation fruit was selected based on the principle of the nearest to the image center when the image had a lot of oscillation fruits. The test result showed that the oscillating fruit was nicely recognized and the recognition time was less than 0.5s for the most cases under the actual harvesting environment.

Abstract:A universal type 3P3R manipulator in the facility agriculture environment such as greenhouse was designed. The kinematics and dynamics of the manipulator were analyzed for operating performance and accurately motion control acquired. The Kane’s method and screw theory were applied to set up the kinematics and dynamics models, respectively. Then in accordance with the models for the manipulator and the structure of the prototype robot manipulator, the operating performance of the manipulator was studied in the Mathematica environment. The orientation variation of the end-effectors and all joint driven torques of the system were obtained according to the planning motion. The result indicates that the correctness, simplicity and validity of the model are verified. Therefore, the dynamic requirements of the manipulator are satisfied with high dexterity. And this research established a foundation for trajectory planning and accurately motion control.

Abstract:In order to set up an integrated greenhouse control system including environmental factors, plant growth period and upper index, relevant literatures of greenhouse control system were analyzed and based on control period principle, the literature was divided into three types of control systems: greenhouse environmental factors control system (fast speed time-varying systems), crop growing period control system (middle speed time-varying systems) and upper index control system in year (slow speed time-varying systems). By the multi-time-scale analysis, three types of control systems were found out to have multi-time-scale property. By means of singular perturbation theory, the greenhouse control system was designed hierarchically at first, and then the overall model of control system of greenhouse and the solution of the controller were obtained within such theoretical framework. Finally, the example and simulation results show that the proposed method is simple, effective and convenient for the application.

Abstract:The optimization design model of embedded giant magnetostrictive components (EGMC) was presented with multi-field property of machinery, electric, magnetic and thermal. And the multi-object genetic algorithm was applied to the optimization design of the EGMC. All optimal objects of the model were confirmed by the general design rules and the requirements of non-cylindrical holes in precision processing. The optimal goals of the model were as follows: a suitable flexural rigid of the EGMC, the maximum torsional rigid of the EGMC, the maximum coil efficiency, the maximum magnetic field density inside the coil, the maximum cooling efficiency of the water-cooling cavity, and the maximum magnetic field density in giant magnetostrictive material (GMM) by reducing the magnetic reluctances. The variables needs optimization included the size of GMM, the magnetic permeability of all magnetic materials, the structure of magnetic flux path, coil, and water-cooling cavity. All optimal parameter ranges were determined by application demands. The finest parameters of giant magnetostrictive components were obtained by non-dominated sorting genetic algorithm (NSGA) with space search method, which were proved by the experiments and magnetic field simulations.

Abstract:Aiming at the phenomenon of the production logistics bottleneck shifting because of uncertain manufacturing circumstances in manufacturing shop, the bottleneck shifting factors was firstly categorized into capability factor, requirement factor and capability-requirement factor, a digital description of bottleneck shifting factors was provided through time-capability factor, time-requirement factor and quality assurance capability factor to offer data for the research on the coupling mechanism of bottleneck shifting factors. Markov chain was used to describe the state space and transition probability of different bottleneck shifting factors and to establish contribution function with the aim of realizing the quantitative analysis on coupling mechanism of bottleneck shifting factors. Taking contribution degree and quality assurance capability as parameters, the mathematic model of the Bottleneck index was then built to measure the possibility of the manufacturing cell becoming bottleneck and to provide production process control and make the optimization with technical support in the further way. An example of forecasting and monitoring the production logistics bottleneck in one manufacturing shop was given to prove the validation and practicability of the prediction method.

Abstract:According to the requirements for the compact structure, large torque, fast response and the other performances of driving system in robot, a joint driving system based on electro-hydrostatic actuation (EHA) technology was proposed. Linear motor, pump and load were integrated to provide larger pressure, simple structure and smart configuration. From the analysis in the magnetic circuit, the electromagnetic piston pump model and its equivalent magnetic circuit were developed to describe the magnetic field and its effect caused by piston’s movement in electromagnetic piston pump. Based on character integrated in mechanical, electrical and hydraulic, the working process model of driving system was built to explore relations between load and system current. Simulation and experimental results show that the proposed system can supply the maximum load pressure of 2.5MPa, work stably at 0~2.4MPa, and reach 1.2MPa/s in pressure response. The proposed driving system can meet the requirements in the robot joint driving.

Abstract:Fluidization characteristics of drops or ice particles in liquid—liquid circulating fluidized bed (LLCFB) for fluid ice production were experimentally studied by means of image gathering and processing. Four typical fluidization characteristics were defined; they were the diffuseness, convergence, adhesion and coalescence of particles. Particles size distributions along the height of LLCFB were obtained. The relativity was revealed between particles fluidization characteristics and fluidization states of LLCFB based on Froude number, Fr and the range of operating parameters combination was discussed which could achieve particulate fluidization states of LLCFB. The results show that the variations of particles fluidization characteristics and sizes distributions are presented by the effect of the height, operating parameters and their combination. The particles diffuseness firstly happened at the bottom of LLCFB, 0.50m, under the influence of particles phase change which further led to the convergence, adhesion and coalescence of particles at the other heights, but the phenomena that larger particles formed due to the coalescence of particles must occur. Fluidization states were estimated by Fr calculation and directly affected by particles fluidization characteristics, its perfect fluidization states and particulate fluidization were mainly appeared at some range of operating parameters, such as smaller volume flow-rate of dispersive liquid and lower velocities and temperature of cycle liquid coolant.

Abstract:Due to the modeling of CNC machine thermal error has characters of small sample and discrete data, the combined modeling method was presented by integrating grey forecast and least square-support vector machine. According to the experimental data of machine temperature and thermal error, a grey forecast model and a least square-support vector machine were built respectively, and then a combination model was established by using weight coefficients. Taking the increase of the synthetic grey correlation between experimental data and the combined model’s forecast value as the aim, optimization of weight coefficients was done. A modeling test was designed on a viaduct gantry machining center, and the result showed that the optimal weights-based combined modeling was prior to grey forecast, least square-support vector machine and multiple linear regressions on accuracy and generalization. Application of the combined model on the online compensation for CNC machine thermal error can effectively reduce the influence of thermal error on machine’s precision.

Abstract:With the definition of the geometry error and the geometric characteristics of sphericity error, a sphericity error evaluation method with the name of mesh search algorithm was presented. The principle of the algorithm was that with the least-square as the initial reference point, and a series of mesh points were collocated around the periphery of the least-square mad self-alignment according to the certain rules, the radius values of all the measured points were calculated by using each mesh point as the ideal center. By comparison and judgment to obtain corresponding evaluation methods (minimum circumscribed sphere (MCS), maximum inscribed sphere (MIS), minimum zone sphere (MZS)).The principle and the realization process of the mesh search algorithm were described in detail. The examples results show that the sphericity error can be evaluated effectively and exactly by using this algorithm.

Abstract:An useful generation algorithm of five-axis NC tool-path was proposed, which contained the following steps: first, the cutter-location driver points were marked out based on the shape of point cloud; second, the instantaneous process area was obtained based on the dynamic index of point cloud data; third, the corresponding cutter location point of each point in the instantaneous process area was obtained and then the cutter location point which has the highest position in the axis direction as the current cutter location point was selected; forth, the limit error was verified according to the adjacent cutter location points, and the precision of tool-path was controlled by the binary interpolation; ultimately, the NC tool-path was generated which met the accuracy requirements. Examples demonstrated that the algorithm can be used for many kinds of tools and can generate the high-quality five-axis NC tool-path for complex data model of unorganized point cloud.

Abstract:Due to the influence of the electromagnetic field and environment, there are spikes in the measured digital signal of carrier machinery. Eliminating the spike accurately is a key work of the digital signal processing. The algorithm based on the racetrack method of eliminating spike was put forward. This algorithm detects the spike according to the changing trends of the data, distinguishes spike and normal data obviously. Compared with the treatment results with amplitude threshold detection and differential threshold detection, the results show that the algorithm based on the racetrack method of eliminating spike is better than the others.