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ON THE TESTING FOR ALPHA-STABLE DISTRIBUTIONS OF ETHERNET NETWORK TRAFFIC

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Journal of electron.cs(China) 2003年第4期20卷 309-312页

作者： Ge Xiaohu Zhu Guanxi Zhu Yaoting (electron. & info. eng. dept., Huazhong Univ. of Sci. & Tech., Wuhan 430074) electron. & info. eng. dept. Huazhong Univ. of Sci. & Tech. Wuhan

The modeling of network traffic is important for the design and application of networks, but little is known as to the characteristics of distribution of packets in network traffic. In this letter the distribution of ... 详细信息

关键词： Alpha-stable distributions Self-similar Maximum likelihood method Network traffic

Research on a Fast-Closing Switch Based Fault Current Limiter with Series Compensation

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Journal of Donghua University(eng.ish Edition) 2002年第3期19卷 23-27页

作者：陈金祥邹积岩董恩源石晶 dept. of Elec. eng. Huazhong Univ. of Sci. and Technol. Wuhan 430070 China dept. of Elec. and electron. eng. Dalian Univ. of Technol. Dalian 116023 China

A new type of fault current limiter (FCL) with series compensation based fast-closing switch is proposed. It is composed of a capacitor bank and a reactor in series. The main control component is a fast-closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. When fault occurs, the switch closes and bypasses the capacitors, and the fault is limited by the reactor then. Simulated analysis and experiments show that it is feasible to develop the FCL with low cost and high reliability. The effectiveness of transient stability for power system is evaluated by digital simulation.

关键词： fault current limiter(FCL), series compensation,fast-closing switch, system stability.

A NEW METHOD FOR DETERMINING THE LOCATION AND Leng.H OF A THIN CYLINDRICAL TARGET WITH RANGE DIFFERENCE OF A MULTISTATIC RADAR SYSTEM

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Journal of electron.cs(China) 2000年第2期17卷 139-145页

作者： Wei Chongyu Xu Shanjia Wang Dongjin (dept. of electron. eng. and info. Sci., Univ. of Sci. and Technol. of China, Hefei 230027) dept. of electron. eng. and info. Sci. Univ. of Sci. and Technol. of China Hefei

This paper describes a short range target location system based on the range difference info.mation of a T-R4 multistatic radar system with FMCW signal. A new method is proposed to determine the location and leng.h of a thin cylindrical target making use of the high resolution of wide band FMCW signal and the spectrum characteristics of the target echo. Formulae are derived for target location and its leng.h estimation being independent of the transmitter position. System performances are simulated with the proposed algorithm and the results are given for various situations.

关键词： Multistatic radar Target location Range difference FMCW

EFFECT OF THE OPEN CRACK ON THE PULL-IN INSTABILITY OF AN ELECTROSTATICALLY ACTUATED MICRO-BEAM

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Acta Mechanica Solida Sinica 2012年第6期25卷 627-637页

作者： Asadollah Motallebi Mohammad Fathalilou Ghader Rezazadeh Mech. eng. dept. Islamic Azad University Mech. eng. dept. Urmia University

In this paper, the effects of the open crack on the static and dynamic pull-in volt- ages of an electrostatically actuated fixed-fixed and cantilever micro-beam are investigated. By presenting a mathematical modeling, the governing static and dynamic equations are solved by SSLM and Galerkin-based Reduced Order Model, respectively. Then, each single-side open crack in the micro-beam is modeled by a massless rotational spring and the cracked mode shapes and corresponding natural frequencies are calculated by considering the boundary and patching con- ditions and using transfer matrix methods. Finally, the effects of the crack dept. ratio, crack position and crack number on the pull-in voltage of the micro-beams are studied. It is shown that beside the residual stresses created in the machining process, the crack（s） can be initiated, growth and consequently change the pull-in voltage of the system by decreasing the natural frequencies. The results show that the crack position is effective beside the crack dept. ratio in decreasing the pull-in voltage. Also it is shown that in the fixed-fixed micro-beam there are several points for the crack location in which, the pull-in voltage is extremum.

关键词： MEMS open crack electrostatic pull-in instability

Poincaré and Poincaré-Cartan integral invariants of a generalized Hamiltonian system

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Communications in Nonlinear Science and Numerical Simulation 2001年第1期6卷 45-49页

作者： Yongxin GUO, Liyan JIANG and Ying YU (Department of Physics, Liaoning University, Shenyang 110026, China Department of electron.cs and info.mation eng.neering, Dandong Advanced Academy, Dandong 118000, China School of Science, Shenyang University of Te Department of Physics Liaoning University Shenyang 110036 China dept. of electron.cs and info. eng. Dandong Advanced Academy Dandong 118000 China School of Science Shenyang University of Technology Shenyang 110023 China

Without Darboux’s transformation, the traditional Hamiltonian formulation of dynamical systems is only suitable to conservative systems or self-adjoint systems. Based on an extension of dynamic space of Birkhoffian systems to a generalized phase space by intro- ducing dummy variables, a generalized Hamiltonian canonical formulation of general systems is constructed, which admits symplectic structure. There exist integral invariants of Poincare and Poincare-Cartan’s type for such systems.

关键词： Birkhoffian systems symplectic structure integral invariants

BLIND MULTIUSER DETECTION FOR V-BLAST CODED MULTICARRIER CDMA SYSTEM

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Journal of electron.cs(China) 2006年第1期23卷 14-19页

作者： Deng.Ke Yin Qinye Zhang Hong Inst. of lnfo. eng. School of Electron. and Info. Eng. Xi＇an Jiaotong University Xi＇an 710049 China

Focusing on the space-time coded multiuser mobile communication systems in the frequency-selective fading environment, this paper proposes a Vertical Bell labs LAyered Space-Time (V-BLAST) coded Multicarrier Code-Division Multiple-Access (MC-CDMA) scheme and its blind channel identification algorithm. This algorithm employs an ESPRIT-like method and the singular value decomposition, and the channels between every transmit antenna of every user and every receive antenna of the base station are blindly estimated with a closed-form solution. Based on it, an equivalent Minimum Mean-Squared Error (MMSE) time-domain multiuser detector is derived. Moreover, the proposed scheme exploits the precoding in the transmitter in order to eliminate the constraint of more receive antennas than transmit ones, required by most conventional V-BLAST codec schemes. Computer simulation results demonstrate the validity of this proposed scheme.

关键词： Multicarrier Code-division multiple-access Vertical Bell labs layered space-time code Multiuser detection

Scattering Characteristics of Liquid Droplets Spun Off from Rotating Disk Edge

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Journal of Thermal Science 2012年第1期21卷 42-48页

作者： Mizue MUNEKATA Akira NOGUCHI Jun NISHIYAMA Hiroaki KURISHIMA Hiroyuki YOSHIKAWA dept. of Mech. System eng. Kumamoto University 2-39-1 Kurokami Tokyo electron.Kyushu Ltd. Fukuhara

Scattering characteristics of liquid droplets spun off from a rotating disk edge are experimentally investigated. In the present research, aluminum disks are utilized and ethanol is employed for liquid. Scattering phenomena of the droplets are captured by the high-speed digital camera. Frequency distribution of the droplet diameter is evaluated from these images and distributions of horizontal flying velocity and angle of the droplets were measured by PTV. Liquid filaments are stretched outward from the stagnant liquid layer by centrifugal force and skew complicatedly by aerodynamic force. Some peaks appear in the distribution of the scattered droplet diameter and they are origi- nated from large terminal droplets and small droplets generated from filamentwise breakup. Most of the scattered droplets fly slightly inside in the tangential direction of the disk edge. The droplets spun off from the thin disk scatter widely compared with that from the thick one.

关键词： Rotating disk Scattering droplet Visualization Particle tracking velocimetry

A VISUAL MODEL WEIGHTED COSINE TRANSFORM FOR HIDING WATERMARK IN IMAGES

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Journal of electron.cs(China) 2000年第4期17卷 357-362页

作者： Li Hua Zhu Yaoting Zhu Guangxi(State Education Commission Laboratory for Image Processing and Intelligent Control) (dept. of electron. and info. eng., Huazhong University of Science and Technology, Wuhan 430074) State Education Commission Laboratory for Image Processing and Intelligent Control China dept. of electron. and info. eng. Huazhong University of Science and Technology Wuhan

Watermarking is a technique for labeling digital pictures by hiding secret info.mation into images. Watermark embedding is a method to discourage unauthorized copying and identify the owner or distributor of digital data. In this paper, a new method is proposed. The watermark is processed as a visually recognizable pattern-binary image, which includes more info.mation than the traditional symbol or ID number and is "extracted" instead of only "detected" to characterize the owner. The watermark is hidden in the host image by selectively modifying the middle-frequency part of the host image in conjunction with the human visual system(HVS) and the image discrete cosine transform(DCT). The experimental results show that this method can survive image cropping and image compression, and get better results, this is also a prospective method.

关键词： Digital watermark DCT transform HVS model Radial frequency

Computational Fluid Dynamic Simulation of Liquid-Liquid Mixing in a Static Double-T-shaped Micromixer

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过程工程学报 2008年第6期8卷 1080-1084页

作者： Elmabruk A. MANSUR 王运东戴猷元 The State Key Lab. Chem. eng. Dept. Chem. Eng.Tsinghua University

The laminar flow structure and mixing performance of T-shaped and double-T-shaped micromixers with rectangular cross-section have been investigated using computational fluid dynamic (CFD) simulation. FLUENT software is used to evaluate the mixing efficiency. The numerical simulation results show that the presented double-T-micromixer is highly efficient over T-shaped micromixer. The performance of double-T-micromixer with and without static mixing elements (SME) is also investigated. The enhancement in mixing performance is thought to be caused by the generation of eddies and lateral velocity component when the mixture flows through these elements. Mixing efficiency as higher as 97% is reached within a mixing leng.h of 320 μm downstream from the first T-junction with the enhancement of three SMEs.

关键词：计算方法流体动力学模拟方法液液混合双T形微混合器物理过程