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August 30,2011
Volume 4,Issue 16
Pages -
Subject Area:Electrical Engineering,Engineering Thermophysics

Title: Analysis on nonlinear factors of doubly fed wind turbine generator system based on double PWM coordinated control

Authors: ZHANG Hao, YE Yuguang, SHAO Guoqing
PP: 1525-1530
Abstract: Based on a variable speed constant frequency doubly fed wind turbine generator model, which is controlled by double pulse-width modulation (PWM) converter, a comparative analysis on a doubly fed induction generator’s mathematical model under three-phase static coordinate system and two-phase synchronization reference frame was carried out in this paper. It pointed out the nonlinear factors which exist in the variable speed constant frequency wind generator, and found that the nonlinear factors can be obviously decreased by coordinate transformation. Further more, by an analysis on a mainstream control scheme of AC-excited power supply for the wind turbine generator, it pointed out that the nonlinear factors which exist in doubly fed wind turbine generator can’t be completely solved by using vector control system’s linear control theory. Finally, some nonlinear decoupling control strategies were discussed and the method for further optimization of variable speed constant frequency doubly fed wind power generator system’s function was pointed out.
Keywords: electric work; doubly fed wind turbine generator system; coordinate transformation; vector control; nonlinear decoupling control; nonlinear factors

Title: Hydrogen production by steam reforming of methanol in a reactor with comby fractal micro-channel network

Authors: SHEN Yinqi, DU Xiaoze, YANG Lijun
PP: 1515-1524
Abstract: According to the catalytic reaction of methanol steam reforming in a micro-channel reactor, a steady-state multi-component transport reaction model in the form of three-dimension was established. By numerical simulations, the reactions in rectangular parallel micro-channels and in comby fractal micro-channel network with catalyst Zn_Cr/CeO2/ZrO2 were studied. Based on the dual-rate model, the effect of the operating condition on the transport law of methanol steam reforming in these micro-channels was investigated, which reflected that these two micro-channels were conducive to the increase of the methanol conversion and the hydrogen production. Meanwhile, compared to the rectangular parallel micro-channels, comby fractal micro-channel network possesses several advantages. For example, its required pump power is much smaller. And under the same heating area, it is able to absorb more heat. Also, comby fractal micro-channel is more conducive to the uniformity of temperature distribution, in turn enhancing methanol conversion and reducing CO. Therefore, it is an ideal channel for hydrogen production in proton exchange membrane fuel cell (PEMFC).
Keywords: engineering thermophysics; micro-channel; methanol reforming; proton exchange membrane fuel cell

Title: Experimental investigation on a new flat-plate type capillary pumped loop

Authors: LIU Zhichun, LIU Bo, GAI Dongxing, CHEN Binbin, LIU Wei
PP: 1509-1514
Abstract: An improved flat-plate type capillary pumped loop (CPL) system is proposed, fabricated and tested in this paper, which aims to eliminate the influence of non-condensed gas (NCG) on system operation. And the qualitative analysis of the influence of NCG on system is conducted. A series of startup and operation capability experiments are carried out under gravity assisted and non-gravity assisted conditions. The experiment results show that, under the gravity assisted condition, CPL could start up smoothly when heat load is in the range of 100 W to 800 W (heat flux up to 2.05 W/cm2); under the non-gravity assisted condition, CPL could start up smoothly when heat load is in the range of 100 W to 500 W (heat flux up to 1.28 W/cm2). The results of operation capability experiments show that the CPL system has the capability of well bearing mutative heat load. The effects of the reservoir set temperature and gravity are also studied in this paper.
Keywords: engineering thermophysics; capillary pumped loop; startup performance; stability; experimental investigation

Title: The design of leakage protection device based on MCU

Authors: JI Wei, ZHANG Jianwen
PP: 1503-1508
Abstract: This paper introduced the characteristics of leakage current in low-voltage power supply system and analyzed the application difference of leakage protection device in different system. It designed a leakage protection device based on micro control unit (MCU) for terra terra (TT) system. The device can detect the phase and amplitude of leakage current, measure the line temperature, prevent fire and link the fire control and handle the fault circuit according to feedback signal. The device can quickly analyze the fault phase, and make appropriate treatment measures based on information fusion technology to achieve intellectualization of leakage protection device. Using Matlab and Protues software to simulate the characteristics of single-phase, two-phase leakage current waveform of TT system and operationally simulate the microcontroller. The results show that the design meets the pratical application requirements.
Keywords: electric power system and automation; leakage protection; analysis of leakage current; micro control unit; Matlab

Title: Innovative design of a tipping institution for self-tipping wagon

Authors: GUO Meiling, CHEN Xiaoliang, ZHOU Yan
PP: 1499-1502
Abstract: This paper has provided a new idea of a tipping institution for self-tipping wagon so that while a hydraulic cylinder is driving the wagon lifting, the door of compartment is opening. In this idea the tipping institution adopts a planar 4-linkage mechanism, through a rod which drives the lift of the wagon, thus realizing a 90-degree turn of the connecting rod. And with the use of a parallelogram linkage consisting of the connecting rod and the door, the rotation of the connecting rod drives the door opening, realizing the unloading of the tipper. The tipping institution is simple in structure and principle, and provides a new design idea of tipper.
Keywords: mechanical design; tipping institution for self-tipping wagon; planar 4-linkage mechanism; Pro/ENGINEER

Title: Study on seal performance of dustproof seal ring based on ANSYS

Authors: ZHANG Qingkui, GAO Xinling, YANG Fan
PP: 1493-1498
Abstract: By using ANSYS software, aiming at the large deformation and nonlinear characteristics of type A dustproof seal ring, established nonlinear finite element analysis model of type A dustproof seal ring with three kinds of rubber and plastic materials, namely fluorine rubber, butyl rubber, polyurethane rubber, the maximum contact stress, the average contact stress and the stress distribution of three kinds of materials were analyzed and contrasted. The result has certain theoretical significance and guiding role for improving the study and design level of type A dustproof seal ring with different materials, and improving seal performance.
Keywords: mechanical design; A type dustproof seal ring; constitutive model; contact problem; nonlinear finite element

Title: The non-resonant design and simulation of apertured conical amplitude transformer in ultrasonic gear honing

Authors: LI Qingfen, LV Ming, WANG Shiying
PP: 1487-1492
Abstract: To study the non-resonant design method of vibration system of ultrasonic gear honing, the frequency equation and the amplification factor formulas of the vibration system are derived based on the wave equation of longitudinal vibration in slender rod and the displacement equation of bending vibration in thin disk, and according to the non-resonance nature and boundary condition of the amplitude transformer. A set of design parameters is obtained by the software of Matlab, the relationship of the frequency equation error, the length of the horn and the vibration frequency of the amplitude transformer is discussed, and the effect of the middle hole in the horn on the amplification factor is studied. From the model analysis of ANSYS, it is concluded that the frequency of the amplitude transformer is consistent with the design results and the non-resonant design method is feasible.
Keywords: mechanical design; ultrasonic gear honing; amplitude transformer; non-resonance; amplification factor; modeling analysis

Title: Dynamic model based on PFC of asphalt concrete cutting process and optimization of tools installation

Authors: XING Guo, ZHOU Liqun, WANG Zhen, TANG Juan
PP: 1481-1486
Abstract: In this paper, based on the superiority of the simulation of the asphalt concrete’s rheological properties with the discrete element method, milling machine cutting process of asphalt concrete was simulated, which overcomes the limitations of the macro continuity hypothesis based on traditional continuum mechanics model, and can make this cutting process visible from microcosmic angle. The research results indicated that the model checked by uniaxial compression test, gets change rule of cutting force and friction force in different cutting angle on cutting knife surface of cutting tools, and gets the conclusion that 5-20 degrees cutting angle in installation work is good to tools’ life.
Keywords: mechanical manufacture and automation; asphalt concrete; discrete element method; cutting force; friction force; optimization of tools installation

Title: Study on control of step motor based on Galil card

Authors: ZHANG Wenchao, LU Hong, WANG Yang, MA Hui, LI Xiangyi
PP: 1476-1480
Abstract: The paper introduces the constructing process of the stepping motor control system，and obtains some optimization methods of the motor control curve. The operation of the stepper motor is controlled by pulse. When the stepper motor driver receives a pulse signal, it drives the stepper motor rotate into a fixed angle in a direction step by step. With the number of pulses, movement control card can control the angular displacement. With the pulse frequency, it can also control the motor rotation speed and acceleration.
Keywords: mechanical manufacture and automation; control curve; Galil; stepper motor; pulse

Title: A silicon wafer optical prealignment method based on shape center method

Authors: LIU Renqiang, LIU Pinkuan, HUANG Chunxia
PP: 1469-1475
Abstract: A wafer prealignment method is designed based on shape center measurement method. The wafer’s shape center is measured by laser displacement sensor from wafer’s radial direction, and the orientation of wafer is measured by notch angle detection using photoelectric laser sensor that detects the position of the wafer’s periphery as a rotation stage rotates. Dynamic error compensation method is applied to eliminate the radial runout effect using two inductance sensor measure the rotation stage’s rotation center. The wafer’s desired position and orientation is obtained from two steps: firstly, coarse alignment is made by adjusting the wafer’s shape center to be concentric with rotation stage’s rotation center and notch angle point to desires orientation, then precise measurement and adjustment is made on the wafer’s notch angle. The experimentation has proved that the use of the runout compensation method has improved the prealignment precision of notch angle orientation to 30 micradians and wafer center to 1 micron.
Keywords: mechanical manufacture and automation; microelectronics manufacture; optical prealignment; shape center of silicon wafer; error compensation

Title: Research on programming and simulation technologies for NC machining planar enveloping hourglass worm

Authors: HU Zihua, WANG Yongxin, GE Chuanzhi, KUANG Zheng, TANG Liang
PP: 1462-1468
Abstract: A five-axis computer numerical control (CNC) flank milling process plan for the planar enveloping hourglass worm is proposed in this paper. Some specific researches are done for the key technologies including solid modeling, pre-processing, post processing and machining simulation of the five-axis flank milling programming by using UG and its development tools, VC++ and VERICUT. The simulation results indicate the feasibility and effectiveness of the proposed five-axis CNC flank milling process plan for the planar enveloping hourglass worm.
Keywords: mechanical manufacture and automation; planar enveloping hourglass worm; five-axis numerical control flank milling; numerical control programming; machining simulation

Title: The study of auto-programming CNC system for tufting machine based on PMAC

Authors: YE Suping, LI Guolong
PP: 1455-1461
Abstract: Based on the PC+NC structure, a processing control system of auto-programming computer numerical control (CNC) for tufting machine was built by the introduction of programmable multi-axis controller (PMAC). It can design the patterning in the AutoCAD, and the computer aided design (CAD)/computer-aided manufacturing (CAM) design platform can be set up by the use of the secondary development of AutoCAD, based on which the coordinates information of the object patterning can be extracted and the NC code can be generated automatically. Combined with the PComm 32 dynamic link library, the Visual C++ was invited to act as the programming language in the CNC’s operating software, thanks to which, the communication between the Windows and PMAC was realized and the Windows’ management capability and the numeric controller’s power were fully explored. Finally, the automatic machining carpet with complex patterning was achieved.
Keywords: electromechanics engineering; computer numerical control system; programmable multi-axis controller; AutoCAD secondary development; tufting machine; auto-programming

Title: Research on the application of thermodynamic theory in cutting system

Authors: WAN Yi, SHAO Fang
PP: 1448-1454
Abstract: Thermodynamic system of cutting was developed with non-equilibrium thermodynamic theory based on local equilibrium hypothesis and conservation equation. In this system, non-equilibrium processes include heat conduction, diffusion, adherence, viscosity plastic flow and chemical reaction. Entropy flow and entropy generation were employed to describe the change in those non-equilibrium processes. Furthermore, interactions among sub-processes were studied with non-equilibrium thermodynamic theory and Curie principle. The results indicate that there is no coupling among sub-processes, while influences still exist through changes of system structure and elements.
Keywords: cutting tool technology; thermodynamic system of cutting; thermodynamics; entropy; entropy generation

Title: Design of industrial accumulator working state remote monitoring system

Authors: LI Hongbo, SUN Peiyan
PP: 1442-1447
Abstract: This paper designs a remote monitoring system for industrial accumulator state measurement by means of controller area network (CAN) bus and MAX232 serial communication. The design can transfer the measured signal to PC computer in the monitoring room, and it is convenient for the operator to supervise. In addition, the serial data acquisition and graphical user interface (GUI) display by Matlab are used. The function of serial data acquisition is supported by Matlab 6.X or Matlab 7.0 and their higher version. Based on the powerful computational capability and the function of visible interface operations, together with its open extensible environment, Matlab software supports different kind of toolbox oriented to various applications, the most typical toolbox is neural network toolbox, so the system could monitor the state of charge in theory. According to the test results, the system, which adapts to the monitor of different environment, has good accuracy, reliability and expansibility.
Keywords: measuring and testing technologies and instruments; industrial accumulator; state remote monitoring; micro control unit; Matlab GUI

Title: The influence of physical defects on the load capacity of hot rolling H-beam

Authors: ZANG Yong, TIAN Shuotao, QU Weizhuang, YUAN Pengju
PP: 1436-1441
Abstract: There are many physical defects which include residual stress and non-uniform material in hot rolling H-beam. In this paper, the residual stress distribution and non-uniform material in hot rolling H-beam are obtained mainly with the measurement method. Based on the stability theory and taken FEA software ANSYS as working platform, the extent of the influence of the physical defects on the ultimate load capacity of H-beam is discussed, and some reference thoughts for the design, production and use of the H-beam are provided.
Keywords: mechanical strength; ultimate load capacity; physical defects; residual stress; H-beam

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