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Traffic-Aware Channelization Medium Access Control for Wireless Ad Hoc Networks

China Communications 2013年第4期10卷 88-100页

作者：史春光赵海涛张少杰马东堂魏急波 College of Electronic Science and Engineering National University of Defense Technolog Department of Technology Taiyuan Satellite Launch Center State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System

Existing multi-channel Medium Access Control (MAC) protocols have been demonstrated to significantly increase wireless network performance compared to single channel MAC protocols. Traditionally, the channelization structure in IEEE 802.11 based wireless networks is pre-configured, and the entire available spectrum is divided into subchannels and equal channel widths. In contrast, this paper presents a Traffic-Aware Channelization MAC (TAC-MAC) protocol for wireless ad hoc networks, where each node is equipped with a single half duplex transceiver. TAC-MAC works in a distributed, fine-grai-ned manner, which dynamically divides variable-width subchannels and allocates subchannel width based on the Orthogonal Frequency Division Multiplexing (OFDM) technique according to the traffic demands of nodes. Simulations show that the TAC-MAC can significantly improve network throughput and reduce packet delay compared with both fixed-width multi-channel MAC and single channel 802.11 protocols, which illustrates a new paradigm for high-efficient multi-channel MAC design in wireless ad hoc networks.

关键词： wireless ad hoc networks multi-channel MAC TAC IEEE 802.11

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Dual-PWM variable frequency control system of mine hoist

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Journal of Computational Information systems 2013年第6期9卷 2131-2137页

作者： Zhang, Liwei Zheng, Guoqiang Li, Jishun School of Electronic Information Engineering Henan University of Science and Technology Luoyang 471003 China Henan Key Laboratory for Machinery Design and Transmission System Henan University of Science and Technology Luoyang 471003 China

Aimed to problems that exist in the regeneration energy feedback technology of the mine hoist, a novel dual-PWM variable frequency control system was proposed for three-phase AC motor in this paper. Compared to the uncontrollable AC-DC-AC topological structure, it was used to achieve the four-quadrant operation, eliminate the harmonic pollution at the grid side and improve the dynamic response of the motor. Direct power control (DPC) is applied to the system rectifier, and direct torque control (DTC) is applied to the inverter. Then the system scheme is modeled and simulated in Matlab/Simulink environment. Simulation results indicate that the dual-PWM converter system can work normally with all performance parameters satisfactory. Copyright © 2013 Binary Information Press.

关键词： Mine hoists

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Direct Power Control strategy of three-phase PWM rectifier

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Journal of Information and Computational science 2013年第9期10卷 2807-2813页

For traditional Direct Power Control (DPC), the switching frequency is not fixed and the characteristics in steady state are not well. In order to solve these problems, a proposed DPC strategy based on virtual flux is designed. Firstly, the mathematical model of three-phase PWM rectifier is presented. Then, the virtual flux estimator is established to calculate the active and reactive power. Finally, the system model is built and simulated in Matlab/Simulink. The electrical waveforms show that the control effect is excellent. The proposed DPC system has simple structure and algorithm, rapid dynamic response, high power factor, fixed switching frequency and low harmonic distortion, and so on. Copyright © 2013 Binary Information Press.

关键词： Reactive power

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A 3-transistor CMOS active pixel with in-pixel correlated double sampling

A 3-transistor CMOS active pixel with in-pixel correlated do...

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IEEE Conference on Electron Devices and Solid-State Circuits

作者： Shaohua Liu Lai Jiang Hang Yu Yan Li Dao ming xi Qingguo Xie Shenzhen City Key Laboratory of Embedded System Design College of Computer Science and Software Engineering Shenzhen University Shenzhen China Shenzhen City Key Laboratory of Embedded System Design College of Computer Science and Software Engineering Shenzhen University Shenzhen China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology HUST Wuhan China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan China

This paper presents a 3-transistor CMOS active pixel structure with in-pixel correlated double sampling. designed in a standard 0.18 μm CMOS process, the structure effectively suppresses temporal noise and fixed pattern noise (FPN), thanks to the shared correlated double sampling circuit inside the pixel. Fill factor is also improved while maintaining pixel performance. Validation by Spectre simulator shows that the proposed structure suppresses 100 mV input offset to the microvolt range, and the pixel readout time is ~90 ns. The average power consumption of each pixel is 18 μW.

关键词： CMOS integrated circuits

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A CMOS time-to-digital converter for multi-voltage threshold method in positron emission tomography

A CMOS time-to-digital converter for multi-voltage threshold...

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IEEE Conference on Electron Devices and Solid-State Circuits

作者： Yan Li Hang Yu Lai Jiang Zhen Ji Jun Zhu Ming Niu Peng Xiao Shenzhen City Key Laboratory of Embedded System Design College of Computer Science and Software Engineering Shenzhen University Shenzhen China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781467325240

Avoiding use of traditional high-speed analog-to digital converters (ADCs) and constant fraction discriminators, multi-voltage threshold (MVT) method is able to digitally sample positron emission tomography (PET) scintillation pulse with reasonable cost. As the key component of the MVT method, a time-to-digital convertor (TDC) with high resolution and large dynamic range is presented in this work. The TDC architecture uses a delay locked loop (DLL) to generate the fast clock edges from a 100 MHz clock, and a 32-stage Vernier delay lines (VDL) is used to achieve the 40pS timing resolution. The proposed TDC is designed using the standard 0.25 μm CMOS technology with 2.5V normal supply voltage. The power consumption of the TDC is ~70 mW.

关键词： CMOS integrated circuits Delays Image edge detection CMOS technology Pulse measurements Cities and towns

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Implicit generalized predictive control for electrical heating box with multi-loop control

Implicit generalized predictive control for electrical heati...

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Chinese Control Conference (CCC)

作者： Fang Yang Zhao-hui Yuan Henan University of Science and Technology Henan Key Laboratory for Machinery Design and Transmisson System China Northwestern Nontechnical University School of Automation China

Electrical heating box with multi -loop control has several features as great inertia and coupling. It is a type of multi-variable system. To solve the problem, a kind of decoupling designed implicit generalized predictive control (IGPC) method is discussed. The Multi-variable IGPC based on decoupling design. Using decentralized objective function and feedforward decoupling, the decoupling IGPC is achieved to control a multi -variable system. According to input and output data, the parameters of optimal control law could be identified through use of Recursive Least Squares (RLS). This method avoids solving Diophantine equations by online. The IGPC is used for control electrical heating box with three multi-loops through simulation study. In the test process, compared with the IGPC effect and traditional PID control effect and analyzed the control effect through changing softness parameter. The test results show that the IGPC could eliminate the coupling between loops and have good control stability.

关键词： Predictive control Electronic mail Resistance heating Educational institutions Couplings Mathematical model Laboratories

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Eddy current pulsed thermography for fatigue evaluation of gear

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AIP Conference Proceedings 2014年第1期1581卷 1652-1662页

作者： Gui Yun Tian Aijun Yin Bin Gao Jishan Zhang Brian Shaw School of Automation Engineering University of Electronic Science and Technology of China Chengdu Sichuan 611731 P. R. China and School of Electrical and Electronic Engineering Newcastle University Newcastle upon Tyne NE1 7RU United Kingdom State Key Laboratory of Mechanical Transmission College of Mechanical Engineering Chongqing University P. R. China and School of Electrical and Electronic Engineering Newcastle University Newcastle upon Tyne NE1 7RU United Kingdom Design Unit School of Mechanical Engineering and System Newcastle University Newcastle upon Tyne NE1 7RU United Kingdom

The pulsed eddy current (PEC) technique generates responses over a wide range of frequencies, containing more spectral coverage than traditional eddy current inspection. Eddy current pulsed thermography (ECPT), a newly developed non-destructive testing (NDT) technique, has advantages such as rapid inspection of a large area within a short time, high spatial resolution, high sensitivity and stand-off measurement distance. This paper investigates ECPT for the evaluation of gear fatigue tests. The paper proposes a statistical method based on single channel blind source separation to extract details of gear fatigue. The discussion of transient thermal distribution and patterns of fatigue contact surfaces as well as the non-contact surfaces have been reported. In addition, the measurement for gears with different cycles of fatigue tests by ECPTand the comparison results between ECPT with magnetic Barkhausen noise (MBN) have been evaluated. The comparison shows the competitive capability of ECPT in fatigue evaluation.

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The effect of battery temperature on total fuel consumption of fuel cell hybrid vehicles

The effect of battery temperature on total fuel consumption ...

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作者： Zheng, C.H. Kim, N.W. Park, Y.I. Lim, W.S. Cha, S.W. Xu, G.Q. Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen University Town 1068 Xueyuan Avenue Shenzhen 518055 China Shenzhen Key Laboratory of Electric Vehicle Powertrain Platform and Safety Technology Shenzhen China School of Mechanical and Aerospace Engineering/SNU-IAMD Seoul National University Bldg. 301 #1505 San 56-1 Daehak-dong Gwanak-gu Seoul 151-742 Korea Republic of Department of Mechanical System Design Engineering Seoul National University of Science and Technology 172 Gongreung 2-dong Nowon-gu Seoul 139-743 Korea Republic of Department of Mechanical and Automotive Engineering Seoul National University of Science and Technology 172 Gongreung 2-dong Nowon-gu Seoul 139-743 Korea Republic of

In order to consider the effect of battery temperature on the total fuel consumption when a Pontryagin's Minimum Principle (PMP)-based power management strategy is applied to a fuel cell hybrid vehicle (FCHV), this paper designates the battery temperature as a second-state variable other than the battery state of charge (SOC) and defines a new costate for the battery temperature in the control problem. The PMP-based power management strategy is implemented in a computer simulation and the relationship among the final values of the two state variables and the total fuel consumption is illustrated based on the simulation results. This relationship is defined as an optimal surface in this research. Using the optimal surface, it can be concluded that considering the battery temperature effect in the PMP-based power management strategy improves the fuel economy of the FCHV. Potential fuel economy gains attributed to consideration of the battery temperature effect are also determined based on the optimal surfaces. Crown Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Fuel economy

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FEA of Biaxial and Triaxial braided composite for effective material property evaluation and effect of braiding angle on the dynamic behavior

FEA of Biaxial and Triaxial braided composite for effective ...

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International Bhurban Conference on Applied sciences & technology, IBCAST

作者： Haris Hameed Mian Gang Wang Rehan Jamshed Muhammad Aamir Raza National Key Laboratory of Science and Technology for Aerodynamic Design and Research School of Aeronautics Northwestern Polytechnical University Xian China CESAT Islamabad Pakistan

ISBN: (纸本)9781467344258

Braided composites are becoming popular especially for structural applications because of their natural tendency to conform to intricate shapes and more balanced properties than unidirectional laminates. In the present work three dimensional finite element analysis (FEA) of Biaxial and Triaxial braided composite have been performed by developing meso-scale model to evaluate the effective material properties of carbon/epoxy materiaal system. A unit-cell based methodology has been adopted to account for the braiding style, matrix and the fiber-matrix interface. The simulations were performed using commercial FEA code ANSYS® and periodic boundary conditions (PBC) has been applied on the unit cells. By varying the braiding angle from 15° to 75°, the effective material properties were predicted and the variation of the engineering constants with the braiding angle was studied. The results obtained were in close agreement with the available experimental data. The technique of developing the meso-mechanical model for analyzing the mechanics of textile composite is very effective. It truly reflects the braided structure and corresponds with the actual pattern of the braided composites. In addition to that the dynamic response of the structure by changing braiding angle was investigated. The vibration analysis showed that the natural frequency of the structure is decreased by increasing the braiding angle.

关键词： Carbon Materials Three-dimensional displays Load modeling Solid modeling Brain modeling

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Analysis of the Propagation of Elastic Wave in Rocks with A Double-Crack Model

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Chinese Journal of Geophysics 2013年第2期55卷 166-176页

作者： Song-Lin XU Yong-Gui LIU Dao-Ying XI Guang-Chang LI Zi-Han TAN CAS Key Laboratory for Mechanical Behavior and Design of Materials University of Science and Technology of China Hefei 230027 China Mengcheng National Geophysical Observatory School of Earth and Space Science University of Science and Technology of China Hefei 230026 China Zhejiang East China Engineering Safety Technology Co. Ltd Hangzhou 310014 China

Rock and rock mass are non-homogeneous medium with complex micro- and meso-scopic structures. Dispersion effect is caused by the interaction between the elastic wave and these micro- and meso-defects in rocks. A double-crack model is used to study the effect of microscopic structures on the dispersion of elastic waves. In the model, the interaction between these two cracks is considered to analyze the effect of multiple scattering. Among these double-crack systems, a linear superposition method is adopted to analyze the localization of the effect of defects in rocks. Mathematically, based on the fundamental solution of wave propagation equation with Green function method, and combined with the boundary integral method, cracks are treated as inner boundaries and dispersion equation is obtained. Furthermore, the difference between these two ways of interaction of cracks is analyzed, and the influence of the micro discontinuity parameters of the double-crack system, pore fluid pressure and unloading on the dispersion of rocks is discussed.

关键词： Rock mass Elastic harmonic wave Dispersion effect Double-crack model Green function solution

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