Analysis,Modeling and Simulation of the Phase shift Full Bridge Zero-Voltage-Switched PWM Converter

Based on the analysis of the phase shift Full Bridge Zero Voltage Switched PWM Converter(FB ZVS PWM converter),a smal signal model is derived,and simulation results of frequency domain and time domain are given.[WT5HZ]     

Numerical Simulation on Confluence of the Two Rivers in Chongqing City

Flows of the confluence of Yangtze River and Jialing River in the city of Chongqing are numerically simulated by using Delft3D Model with staggered grids and ADI integral method. The water level, flow velocity and drogue trace are studied. Comparing the numerical results with observed data shows good agreement. Therefore the computational model and the simplified parameters are of good accuracy and have practical meaning. The results show that the contamination will linger near the Caiyuanba area and drift to Chaotianmen and the right bank of Yangtze River upstream. The results can be used to forecast flood, inspect contamination and management of riverway in the city.     

Modelling and Simulation of Anoxic Biofilter for Municipal Wastewater Treatment

For a further understanding of biofilter, a mathematical model is developed based on the analysis of the main effects on the up flow anaerobic biofilter(UFAB), which can characterize not only the substrate removal dynamics but also the gradual biofilter clogging. The model considers three aspects: the biological reaction, deep filtration and hydrodynamics, and consists of flow rate of UFAB, the substrate and suspend solid concentration in the influent, and diameter, surface area, porosity of support medium. By applying the model to the experimental UFAB, and contrasting the simulated and experimental data, the authors prove the model can simulate availably the performance of the biofilter, which is operated on different loading and environment. The model can be used as an effective tool for the wastewater treatment plants operation management and the biofilter optimizing design accurately.     

The Conversion Calculation and Graph Simulation about Engineering CAD of CNC Pipe Bender

Some conversion calculation formulas from the XYZ axises to PRB axises of CNC Pipe Bender are set up.The calculation model of graph simulation about moving process of Pipe Bender is set up.Finaly a CAD software is programmed.     

One-dimensional Water Flow Modeling for Chongqing Region at Two Typical Storage Levels in the Three-Gorges Reservoir

The one-dimensional flow model based on Saint-Venant equation is developed.Then,it is applied to calculate the holistic hydraulic characteristics in the natural condition of the Three Gorges Reservoir in Chongqing region,which is the 500 km-long mainstream beginning at Cuntan and ending at the boundary of Chongqing.Further,the model is applied to predict the hydraulic characteristics of the calculating zone at the time of the second stage of the dam construction(156 m storage level at the dam) and the completion of the project(175 m storage level at the dam).When the reservoir is operated at the storage level of 156m,the river-width of most corss-section increasing 2 times and the cross-section average velocity is reduced by 2/3 compared with these in the natural condition.When the reservoir is operated at the storage level of 175 m,the river-width of most cross-section increasing 2.5 times and the cross-section average velocity is reduced by 3/4 compared with these in the natural condition.The validating result indicates that the model properly reflectes the holistic hydraulic characteristics.This model is an effective tool for the assessment of the environmental impacts of the Three Gorges operated at the different storage level.     

Simulation for the Power System of Fuel Cell/battery Electric Vehicle

The developmemt and research of taking fuel cell /battery as electric vehicle power is a new direction in abroad. A real-time simulation model for power driving system of a fuel cellbattery powered electric virtual vehicle is established. This electric vehicle powered primarily by 30 kw proton exchange membrane (PEM)fuel cells, with Lead-acid battery as assistant power, and with focus classis as virtual vehicle classis.The electric vehicle is simulated on the advisor platform, and the NEDC driving pattern simulation results show that the electric vehicle can satisfy the need of performance.     

A mathematical description of the liquid flows inside blast furnaces

The knowledge of liquid flows in blast furnaces may play an important role in controlling the blast furnace process. Appropriate assumptions are given to represent the main characteristics of the liquid flow in blast furnaces, such as liquid streams being composed of unwetting liquid droplets, inertial force having little effect on the liquid flows, and mass exchange existing along the direction perpendicular to liquid flow. A mathematical model is built to predict the distribution of the liquid flow rate and the liquid flow range in packed beds. The scale of the numerical grid used to solve this model may not necessarily be reduced to the particle level. The predicted results of this model accord well with the observed data. This model is an alternative theory for the simulation of blast furnaces     

Simulation Modeling and Simulation Analysis for the Boiler Attached to 360 MW Unit

Using modular simulation technique,a mathematical model for the combustion and air/gas system of the W shape flame boiler is presented.The experimental resulats show that.The dynamic process accords with the mechanism process of the object.     

旱地玉米双相覆盖技术在太原地区的增产效果与机理

玉米双相覆盖技术在太原生态区增产率为１４．４８％。具有苗期适宜增温促发、中期保墒促长的土壤环境效应。增产机理是：玉米地上部和地下部协调增长，叶面积大，茎秆还原糖贮量多，干物质积累也多；具持续高强度灌浆特性，加快了物质运转速度     

Dynamic Modeling and Simulation of 440 t/h Steam-cooled Cyclone Separator for CFB Boiler

A dynamic mathematical model of the steam-cooled cyclone separator in a 440 t/h CFB boiler has been established.Based on the mathematical model,simulation model of the cyclone separator is created with the advanced continuous simulation language(ACSL).The validity of this model has been verified by the simulation experiments and analysis.This model can provide a theoretical guidance for operation and optimal design of the cyclone separator.     

Effect of Fabrication Technology on the Performance and Structure of Stearic Acid/Attapulgite Composite Phase Change Materials

Two kinds of stearic acid (SA)/ attapulgite (ATTP) composite phase change materials (PCMs) were prepared for the latent heat thermal energy storage (LHTES) in buildings or other area by the methods of fusion and immersion, using SA as PCMs and ATTP supplied by Linze of Gansu province as supporting material. The structure, thermal properties, thermal reliability and heat storage or release performance of the composite PCMs were determined by scanning electron microscope (SEM), fourier transformation infrared (FTIR), differential scanning calorimetry (DSC) and thermal cycling test analysis technique. The results indicate that the preparation method has no effect on the structure and morphologies of the composites. Two kinds of composites have same structure due to the SA adsorbed in the surface of ATTP by physical reaction. The results also show that two form-stable composites PCMs have the optimal effect for preventing SA leak from the composite emerges when the maximum load proportion of SA in the composites were 38.64wt% and 29.13wt%. The latent heats and phase change temperature were measured as 68.71 J/g and 57.3℃ for the composite which was prepared by fusion method and 51.79 J/g and 55.2℃ for the composite fabricated by immersion method, respectively. The results of DSC, FTIR and thermal cycling test are all showing that two kinds of composites have good heat storage property but the composite prepared by fusion method has a better thermal and chemical stability.     

Modeling and Simulation Analysis of the Electromechanical Coupling Facts about Precision Transmission System

Electro-mechanical coupling facts about transmission system influence dynamic characteristic and response characteristic of servo system. The coupling factors of precision transmission system are put forward, and the modelling methods of electro-mechanical system are analyzed. Based on the large-scale precise horizontal machining center, the dynamic chart of servo feed system is gained through analyzing mathematical model of the taehes, and the influence on transmission stiffness and transmission error is simulated in precision transmission system. Through changing parameters in servo feed system, the influence on dynamic characteristic and response characteristic is analyzed, so it provides a mathematical model for parameter optimization.     

Critical Phase Transition of the Two-dimensional Microcanonical Ising Model by Cellular Automata Q2R Method

The authors construct a microcanonical ensemble system and analyzes the phase change of the two-dimensional Ising model Cellular Automata Q2R/WQ2R method. The result indicates that the numerical value simulation can show the spontaneous magnetization of two-dimensional crystal lattice in isolated system. The authors have observed the critical phase transition phenomenon and gotten the critical energy. The simulation of three-dimensional Ising model can be grounded on the method that this article establishes.     

Power Model of Bond Graph and Dynamic Simulation of Hoist System for Multi-Flow Transmission

The double drive hoist reducer developed in the planetary gear is a new generation of energy saving and environment protecting hoist product. The multi flow transmission system theory of hoist is analyzed. With the theory and method of bond graph,a bond graph model with coupled vibration is established for hoist multi flow transmission system for the first time. The state equation of the system is developed and dynamic simulation analysis is also carried out. The internal changing law and relationship of the system for the state variable are got. Therefore, the dynamic properties and gearing features of this system are revealed comprehensively. The research results can provide the dynamic analysis method and design basis for multi flow transmission system of hoist.     

橡胶树光合与干物质积累模拟模型研究

基于单叶光合速率的光响应模型和冠层光的分布规律,通过积分形式,构建了橡胶树冠层光合作用模拟模型。模型充分量化了光通量密度、温度、叶面积指数、单叶最大光合速率、光合作用特征参数、消光系数、群体反射率等因子对橡胶树冠层光合速率的影响。在分别确定了叶片和木质器官与环境因子作用关系的基础上,构建了橡胶树的群体呼吸作用模型。在橡胶树冠层的光合作用模型和群体呼吸作用模型的基础上,整合成橡胶树干物质积累模拟模型。模型经初步检验,结果表明模拟值与观测值吻合度较好,模型不仅具有较强的机理性而且具有较高的预测性和实用性。     

Macroscopic and Microscopic Coupling Mathematical Model for Solidification Process of Twin-roll Thin Strip

A macroscopic and microscopic coupling mathematical model for solidification process of twin-roll thin strip is developed. In the model, the latent heat is treated by the enthalpy method, and the grid and node are divided by assumed streamline boundary. The heterogeneous nucleation and the columnar-equiaxed transform(CET)model are introduced, together with the revison of the dendrite growth dynamic model of KGT. With the help of solid fraction, the coupling of the macro/micro aspects is realized by using different grid-sizes and time-steps, macro and micro, together with the columnar dendrite front tracing. The columnar dendrite arm spacing and deflection angle calculated by proposed model are in agreement with the experimental ones. Therefore, the model is proved to be reliable, and it can be used to predict the effects of the processing parameters on the solidification structure of twin-roll thin strips.     

Parameter Design for the Power Train and Simulation of the Dynamic Performance of Elctrical Vehicle

The method and principle of the parameter design for the power train of EV is explored and discussed,then the parametersof EV. based on SC7101 are reasonably selected.The method of calculating the SOC of Lead_acid battery is provided and the relation among the electromotive force,the interior resistance, the polarized resistance and the SOC are analyzed. The capacity is compensated according to the relation between the capacity and the temperature, which is the basis on which the energy management system is designed and improved. The dynamic model which reflects the dynamic characteristics of the power train is established,then the dynamic performance of the EV based on SC7101 is simulated, and the factors that affect the continuous mileage of EV are analyzed,the measures to increase the continuous mileage are provided.The result shows that the analysis of the electric characteristics of battery and the dynamic model are correct,and the dynamic performance perfectly meets the need of the design target.     

厅堂侧向能量因子的仿真与实测

侧向能量因子是衡量厅堂空间感的重要客观指标之一。厅堂侧向能量因子通常采用计算机仿真的方法得到。首先采用MKH800电容型传声器在实际厅堂中开展侧向能量因子测试工作。然后,通过ODEON6.5建立厅堂三维仿真模型,计算相同位置处侧向能量因子的模拟值,并将实测值与模拟值进行对比分析。研究结果表明,各点位的仿真值均大于实测值,座席区前部偏差较小,正对舞台中后部区域偏差较大。造成偏差的主要原因是由于ODEON软件中扩散系数的设置与所在面特性无关,同时,软件无法分别定义各频段的扩散系数。因此,在实际工程项目中,为了准确地预测室内音质效果,建议普遍采用缩尺模型实验测量侧向能量因子。