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Tsinghua Science and Technology

Issue 3 • Date June 2002

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Displaying Results 1 - 25 of 28
  • [Front cover]

    Publication Year: 2002, Page(s): c1
    IEEE is not the copyright holder of this material | PDF file iconPDF (60 KB)
    Freely Available from IEEE
  • Contents

    Publication Year: 2002, Page(s): 1
    IEEE is not the copyright holder of this material | PDF file iconPDF (155 KB)
    Freely Available from IEEE
  • Boltzmann equations with quantum effects (1): Long time behavior of spatial decay solutions

    Publication Year: 2002, Page(s):215 - 218
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (348 KB)

    The Boltzmann equations for Fermi-Dirac particles and Bose-Einstein particles, both in the absence of external force fields, are combined into a more general form called the Boltzmann equation with quantum effects (BQE). It is assumed that the initial data f(x, v, 0) satisfies 0 ≤ f(x, v, 0) < cΦ(x, v, 0) for a positive constant c and certain types of control functions Φ... View full abstract»

    Open Access
  • Boltzmann equations with quantum effects (2): Entropy identity, existence and uniqueness of spatial decay solutions

    Publication Year: 2002, Page(s):219 - 222
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (346 KB)

    A previous study[l] is continued by investigating the Boltzmann equation for particles with quantum effects (BQE). First, the corresponding entropy identity is proved, then if the initial data f(x, v, 0) satisfies 0 ≤ f(x, v, 0) ≤ CΦ (x, v, 0) for a constant 0 < C < ∞ and function Φ(x, v, t), we prove the existence and uniqueness of spat... View full abstract»

    Open Access
  • Two ARCH models and their limitations as diffusion processes

    Publication Year: 2002, Page(s):223 - 227
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (424 KB)

    Two typical ARCH models: the ASDARCH model and the APARCH model are analyzed. Let Yk, and σ2k denote the log returns and the volatility. When the time interval h goes to zero, (Yk; σ2k), as a discrete time Markov chain system, weakly converges to a continuous time diffusion process. The continuous time approximation of... View full abstract»

    Open Access
  • Mixed finite element method and higher-order local artificial boundary conditions for exterior 3-D Poisson equation

    Publication Year: 2002, Page(s):228 - 234
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (502 KB)

    The mixed finite element method is used to solve the exterior Poisson equations with higher-order local artificial boundary conditions in 3-D space. New unknowns are introduced to reduce the order of the derivatives of the unknown to two. The result is an equivalent mixed variational problem which was solved using bilinear finite elements. The primary advantage is that special finite elements are ... View full abstract»

    Open Access
  • Generalization of Hopf functional equation

    Publication Year: 2002, Page(s):235 - 242
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (501 KB)

    This paper generalizes the Hopf functional equation in order to apply it to a wider class of not necessarily incompressible fluid flows. We start by defining characteristic functionals of the velocity field, the density field and the temperature field of a compressible field. Using the continuity equation, the Navier-Stokes equations and the equation of energy we derive a functional equation gover... View full abstract»

    Open Access
  • RCC arch dam structure on the Taxi River and Water storage measure during construction

    Publication Year: 2002, Page(s):243 - 250
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (628 KB)

    The new structure of roller compacted concrete (RCC) arch dams is presented for extremely cold and earthquake prone areas. The influence of construction plans and improved materials on the stresses in the Taxi River dam is also given. Earlier impoundment of water is shown to not only benefit the engineering design but also improve the stresses during construction in winter. Low cement content in t... View full abstract»

    Open Access
  • Experimental study of turbulent wake behind a sine shaped Island in a Shallow-Water layer layer

    Publication Year: 2002, Page(s):251 - 253
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1261 KB)

    A series of experiments is conducted to study shallow-water flow in the wake of a sine shaped island. Digital particle imaging velocimetry (DPIV) is used to measure velocities in the turbulent wake behind a sine shaped island for different characteristic coefficients S. Flow streamlines are given for the wake flows. The measured results show that the characteristic coefficient S is uniquely relate... View full abstract»

    Open Access
  • Stochastic boundary element analysis of concrete gravity dam

    Publication Year: 2002, Page(s):254 - 257
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (331 KB)

    Stochastic boundary integral equations for analyzing large structures are obtained from the partial derivatives of basic random variables. A stochastic boundary element method based on the equations is developed to solve engineering problems of gravity dams using random factors including material parameters of the dam body and the foundation, the water level in the upper reaches, the anti-slide fr... View full abstract»

    Open Access
  • Dimensional synthesis design of novel parallel machine tool

    Publication Year: 2002, Page(s):258 - 262
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (400 KB)

    This paper presents dimensional synthesis design theory for a novel planar 3-DOF (degrees of freedom) parallel machine tool. Closed-form solutions are developed for both the inverse and direct kinematics. The formulation of the dexterity and the definitions of the theoretical workspace and the valid workspace are used to analyze the effects of the design parameters on the dexterity and workspace. ... View full abstract»

    Open Access
  • Optimal nonlinear filter for INS alignment

    Publication Year: 2002, Page(s):263 - 269
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (501 KB)

    All the methods to handle the inertial navigation system (INS) alignment were sub-optimal in the past. In this paper, particle filtering (PF) as an optimal method is used for solving the problem of INS alignment. A sub-optimal two-step filtering algorithm is presented to improve the real-time performance of PF. The approach combines particle filtering with Kalman filtering (KF). Simulation results... View full abstract»

    Open Access
  • Experimental and theoretical study of Young modulus in micromachined polysilicon films

    Publication Year: 2002, Page(s):270 - 275
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (905 KB)

    The elastic modulus is a very important mechanical property in micromachined structures. Several design issues such as resonant frequencies and stiffness in the micromachined structures are related to the elastic modulus. In addition, the accuracy of results from finite element models is highly dependent upon the elastic modulus. In this study, the Young modulus of micromachined thin polysilicon f... View full abstract»

    Open Access
  • Casimir force correction between parallel polysilicon plates

    Publication Year: 2002, Page(s):276 - 280
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (494 KB)

    Both the size of the components and the separation between them in some microelectromechanical systems (MEMS) are already in the sub-micrometer regime, where quantum mechanical effects such as the Casimir effect will need to be considered. This paper theoretically analyzes the roughness, electrical conductivity, and temperature corrections due to the Casimir force between two parallel polysilicon ... View full abstract»

    Open Access
  • Optimal configuration of a redundant robotic arm: Compliance approach

    Publication Year: 2002, Page(s):281 - 285
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (361 KB)

    Applications of robots in tasks where the robot's end-effector bears loads, such as manipulating or assembling an object, picking-and-placing loads, grinding or drilling, demand precision. One aspect that improves precision is the limitation, if not elimination, of manipulator compliance. This paper presents a manipulator compliance optimization approach for determining an optimal manipulator conf... View full abstract»

    Open Access
  • Numerical simulation model of laminar hydrogen/air diffusion flame

    Publication Year: 2002, Page(s):286 - 290
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1580 KB)

    A numerical simulation model is developed for a laminar hydrogen/air diffusion flame. Nineteen species and twenty chemical reactions are considered. The chemical kinetics package (CHEMKIN) subroutines are employed to calculate species thermodynamic properties and chemical reaction rate constants. The flow field is calculated by simultaneously solving a continuity equation, an axial momentum equati... View full abstract»

    Open Access
  • Acoustic signal feature extraction of vehicle targets

    Publication Year: 2002, Page(s):291 - 293
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (218 KB)

    Acoustic signal feature extraction is an important part of target recognition. The mechanisms for producing acoustic signals and their propagation are analyzed to extract the features of the radiated noise from different targets. Analysis of the acoustic spectra of typical vehicle targets acquired outdoors shows that the vehicles can be classified based on the acoustic spectra and amplitudes. View full abstract»

    Open Access
  • Modeling of a cooperation environment in a virtual enterprise

    Publication Year: 2002, Page(s):294 - 298
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (377 KB)

    Virtual enterprises (VEs) are the most promising structure for future enterprises. The cooperative environment of VEs is investigated in this paper. The cooperation in a VE is a process and the depth of the cooperation and the information transparency change in different phases of the cooperation. A tri-layered cooperative structure pattern is discussed with a tri-layered cooperative process model... View full abstract»

    Open Access
  • Hierarchical least squares identification and its convergence for large scale multivariable systems

    Publication Year: 2002, Page(s):299 - 304
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (413 KB)

    The recursive least squares identification algorithm (RLS) for large scale multivariable systems requires a large amount of calculations, therefore, the RLS algorithm is difficult to implement on a computer. The computational load of estimation algorithms can be reduced using the hierarchical least squares identification algorithm (HLS) for large scale multivariable systems. The convergence analys... View full abstract»

    Open Access
  • Dispersion compensation of 180-km 10-Gb/s transmission system using chirped fiber grating

    Publication Year: 2002, Page(s):305 - 308
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (375 KB)

    Many methods have been suggested to reduce dispersion in optical fiber communication. Among these methods, chirped fiber grating (CFG) is a promising scheme. This paper describes a linearly chirped fiber grating with 95% reflectivity and 0. 3 nm bandwidth written using a double exposure method with a uniform phase mask. The CFG resonant wavelength is 1554. 5 nm and dispersion is 1700 ps/nm. Disper... View full abstract»

    Open Access
  • Bi-spectrum scattering model for conducting randomly rough surface

    Publication Year: 2002, Page(s):309 - 316
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (580 KB)

    A scattering model is developed to predict the scattering coefficient of a conducting randomly rough surface by analyzing the randomly rough surface in the spectral domain using the bi-spectrum method. For common randomly rough surfaces without obvious two-scale characteristics, a scale-compression filter can divide the auto-correlation spectrum into two parts with different correlation lengths. T... View full abstract»

    Open Access
  • Image mosaicing algorithm for rolled fingerprint construction

    Publication Year: 2002, Page(s):317 - 321
    Cited by:  Patents (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1492 KB)

    Fingerprint identification is one of the most important biometric authentication methods. However, current devices for recording digital fingerprints can only capture plain-touch fingerprints. Rolled fingerprints have much more information for recognition, so a method is needed to construct a rolled fingerprint from a series of plain-touch fingerprints. This paper presents a novel algorithm for im... View full abstract»

    Open Access
  • In-plane elastic buckling of arch

    Publication Year: 2002, Page(s):322 - 325
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (318 KB)

    The in-plane elastic buckling behavior of arches is investigated using a new finite-element approach for the nonlinear analysis. The linear buckling, nonlinear primary buckling, and secondary bifurcation buckling behavior of arches are compared taking into account the large deformation and the effects of initial geometric imperfections or perturbations. The theoretical investigation emphasizes the... View full abstract»

    Open Access
  • Large eddy simulation of flow field in vector flow clean-room

    Publication Year: 2002, Page(s):326 - 330
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (428 KB)

    The turbulent large eddy simulation (LES) technique and the finite element method (FEM) of computational fluid dynamics (CFD) are used to predict the three-dimensional flow field in a vector flow clean-room under empty state and static state conditions. The partly expanded Taylor-Galerkin (TG) discretization scheme is combined with implicit stream-upwind diffusion in the finite element formulation... View full abstract»

    Open Access
  • Prof. Gavriel Salvendy: On the publication of Tisinghua science and technology

    Publication Year: 2002, Page(s): 222
    IEEE is not the copyright holder of this material | PDF file iconPDF (120 KB)
    Open Access

Aims & Scope

Tsinghua Science and Technology (Tsinghua Sci Technol) aims to highlight scientific achievements in computer science, electronic engineering, and other IT fields. Contributions all over the world are welcome.

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Meet Our Editors

Editor-in-Chief
Professor Jiaguang Sun
School of Software
Tsinghua University
Beijing  100084 China
journal@tsinghua.edu.cn
Phone:86-10-62771385