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Tsinghua Science and Technology

Issue 4 • Date Dec. 2000

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Displaying Results 1 - 25 of 29
  • [Front cover]

    Publication Year: 2000, Page(s): c1
    IEEE is not the copyright holder of this material | PDF file iconPDF (7227 KB)
    Freely Available from IEEE
  • Contents

    Publication Year: 2000, Page(s): 1
    IEEE is not the copyright holder of this material | PDF file iconPDF (198 KB)
    Freely Available from IEEE
  • Dynamic modeling and parameter identification of power systems

    Publication Year: 2000, Page(s): 408
    IEEE is not the copyright holder of this material | PDF file iconPDF (191 KB)
    Open Access
  • Development of the field of flexible AC transmission systems (FACTS)

    Publication Year: 2000, Page(s): 413
    IEEE is not the copyright holder of this material | PDF file iconPDF (169 KB)
    Open Access
  • Atomic ionization by electron impact

    Publication Year: 2000, Page(s):339 - 342
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (911 KB)

    The field of atomic ionization by electron impact is several decades old. In that period of time significant progress has been made in several aspects of the problem and we have learned a lot about ionizing collisions as a result of this work. Over the years both the experiments and theories have improved dramatically. Experiments are now able to measure absolute triple differential cross sections... View full abstract»

    Open Access
  • Spin effects in collisions of electrons with atoms and molecules

    Publication Year: 2000, Page(s):343 - 353
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (2408 KB)

    Some recent experimental and theoretical work on spin-dependent electron-atom and electron-molecule collisions is reviewed. The spin is involved in such collisions by explicit spin-dependent interactions such as the spin-orbit interaction of the continuum electron — Mott scattering but also by exchange which in conjunction with the Pauli principle gives rise to observable spin exchange effe... View full abstract»

    Open Access
  • One-dimensional anisotropic band gap structure

    Publication Year: 2000, Page(s):354 - 359
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1060 KB)

    The band gap structure of one-dimensional anisotropic photonic crystal has been studied by means of the transfer matrix formalism. From the analytic expressions and numeric calculations we see some general characteristics of the band gap structure of anisotropic photonic crystals each band separates into two branches and the two branches react to polarization sensitively. In the practical case of ... View full abstract»

    Open Access
  • Mathematical model of extrinsic blood coagulation cascade dynamic system

    Publication Year: 2000, Page(s):360 - 364
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (964 KB)

    The blood coagulation system is very important to life. This paper presents a mathematical blood coagulation model for the extrinsic pathway. This model simulates clotting factor VIII which plays an important role in the coagulation mechanism. The mathematical model is used to study the equilibrium stability orbit structure attractors and global stability behavior with conclusions in accordance wi... View full abstract»

    Open Access
  • Wavelet-galerkin method for the singular perturbation problem with boundary layers

    Publication Year: 2000, Page(s):365 - 369
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (955 KB)

    A Wavelet-Galerkin method is proposed to solve the singular perturbation problem with boundary layers numerically. Because there are boundary layers in the solution of the singular perturbation problem the approximation spaces with different scale wavelets and boundary bases are chosen. In addition the computation of the inner integrals is transformed to an eigenvalue problem. Therefore a high acc... View full abstract»

    Open Access
  • Lower bound for ideal class numbers of real quadratic function fields

    Publication Year: 2000, Page(s):370 - 371
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (465 KB)

    In this paper the theory of continued fractions of algebraic functions will be used to give a general theorem on lower bounds for class numbers of real quadratic function fields K = k (\sqrt {D}) . The bounds are given more explicitly for six types of real quadratic function fields. As a consequence six classes of real quadratic function fields with ideal cl... View full abstract»

    Open Access
  • Ideal class groups and subgroups of real quadratic function fields

    Publication Year: 2000, Page(s):372 - 373
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (455 KB)

    In this paper we study the real quadratic function fields K = k (\sqrt {D}) , given a necessary and sufficient condition for the ideal class group H K of any real quadratic function field K to have a cyclic subgroup of order n and obtained eight series of such fields. The ideal class numbers h(Ok) of K in the series all have a factor n. View full abstract»

    Open Access
  • Nonlinear time series model for shape classification using neural networks

    Publication Year: 2000, Page(s):374 - 377
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (812 KB)

    A complex nonlinear exponential autoregressive CNEAR model for invariant feature extraction is developed for recognizing arbitrary shapes on a plane. A neural network is used to calculate the CNEAR coefficients. The coefficients which constitute the feature set are proven to be invariant to boundary transformations such as translation rotation scale and choice of starting point in tracing the boun... View full abstract»

    Open Access
  • Determination of mechanical properties of micromembranes with compressive residual stress

    Publication Year: 2000, Page(s):378 - 382
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1246 KB)

    A novel model of a load-deflection method to determine the mechanical properties of micromembranes with compressive residual stress is described. Since thin film structures are frequently used in micro devices characterisation of mechanical properties of thin films is desired by the design and fabrication of micromachines. In this paper the mechanical properties of thin micromembranes under compre... View full abstract»

    Open Access
  • Optimal nesting for continuous shape stamping processes

    Publication Year: 2000, Page(s):383 - 390
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1441 KB)

    This paper discusses the optimal nesting problem for minimizing the scrap in continuous shape stamping processes. The shape sliding technique is used to propose a new approach OVERLAP-and-ESCAPE to solve the problem of continuously nesting shapes onto a metal coil of fixed or selectable width. The approach is used to construct the objective function of the mathematical model of the problem using t... View full abstract»

    Open Access
  • Numerical investigation of separated plug nozzle flow

    Publication Year: 2000, Page(s):391 - 394
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1177 KB)

    Modern analysis techniques that provide improved viability have enabled further investigation of plug nozzle rocket engines as advanced launch vehicle concepts. A plug nozzle for future single-stage-to-orbit vehicles in China has been designed and the flow field in the plug nozzle has been studied numerically for different ambient pressures. Calculations were performed by solving the Navier-Stokes... View full abstract»

    Open Access
  • Numerical investigation of dynamic effects on unsteady flow measurements using a two-dimensional probe

    Publication Year: 2000, Page(s):395 - 399
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1121 KB)

    The dynamic effects in measurements of unsteady flow when using a probe with quasi-steady calibration curves has been investigated in this paper by numerical simulation of the compressible flow around a fixed two-dimensional 3-hole probe. The unsteady velocity and pressure distributions as well as the hole-pressures are calculated for high frequency flow variations. The measurement errors caused b... View full abstract»

    Open Access
  • Numerical investigation of the influence of reynolds number on probe measurements

    Publication Year: 2000, Page(s):400 - 403
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (895 KB)

    The influence of Reynolds number Re on probe measurements was investigated numerically including the effects of the pressure holes and their geometry to obtain accurate hole-pressures. The results indicate that Re influences the probe measurements and cannot be neglected for Re larger than 105 and that the influence increases with Mach number Ma. The calculations show that the pressures... View full abstract»

    Open Access
  • Luminous flame temperature distribution measurement using the emission method

    Publication Year: 2000, Page(s):404 - 408
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (947 KB)

    Flame temperature distribution is one of the most important characteristic parameters in combustion research. The emission method is a good way to measure the luminous flame temperature field. The maximum entropy method is introduced to the temperature distribution measurement of a luminous flame using the emission method. A simplified mathematical model was derived by combining the thermal radiat... View full abstract»

    Open Access
  • Principle and implementation of an MC4044-based phase locked loop for constant speed control

    Publication Year: 2000, Page(s):409 - 413
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1098 KB)

    An inexpensive MC4044-based phase locked loop for constant speed control of a DC motor is discussed. It operates on a principle similar to that of a frequency synthesizer. The paper introduces the system configuration with a detailed description of its operating principle some practical design considerations are discussed with an experimental study to test the control performance of the newly desi... View full abstract»

    Open Access
  • A new method for dressing fine grain diamond wheels the soft-elastic elastic dressing method

    Publication Year: 2000, Page(s):414 - 418
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1041 KB)

    This paper describes a completely new dressing technique the soft-elastic dressing method which can effectively dress fine grain diamond wheels. A rotating and vibrating abrasive belt is used in the soft-elastic dressing method. The principle of the new dressing technique and the soft-elastic dressing equipment are presented. Factors that influence the truing efficiency truing precision and sharpe... View full abstract»

    Open Access
  • Optimization method for turbine airfoil designing using genetic algorithms — CFD and parallel computing

    Publication Year: 2000, Page(s):419 - 423
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (991 KB)

    An optimization method to design turbine airfoils using a Genetic Algorithm • GA design shell coupled directly with a viscous CFD Computational Fluid Dynamics analysis code is proposed in this paper. The blade geometry is parameterized and the optimization method is used to search for a blade geometry that will minimize the loss in the turbine cascade passage. The viscous flow prediction co... View full abstract»

    Open Access
  • Condensation-induced steam bubble collapse in a pipeline

    Publication Year: 2000, Page(s):424 - 427
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1134 KB)

    Steam bubbles often occur in pipelines due to the pipeline structure or operational errors. The water hammer force induced by the steam bubble collapse is a hidden safety concern. This paper experimentally and numerically investigates the conditions for steam bubble formation and collapse. A series of video pictures taken in the laboratory show that steam bubbles form and collapse over several cyc... View full abstract»

    Open Access
  • Induction of apoptosis in protoplasts and suspension cultures of plant cells

    Publication Year: 2000, Page(s):428 - 431
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1587 KB)

    Many studies have showed that apoptosis exists in plants. Our study shows that (1) menadione-VK3 induces apoptosis in suspension cultures of carrot celis; (2) heat shock induces apoptosis in suspension cultures of tobacco cells; and (3) ethrel induces apoptosis in carrot protoplasts. Some important indications of apoptosis were observed including DNA laddering TUNEL-positive reaction condensation ... View full abstract»

    Open Access
  • Feasibility of using chitosan in nerve repair

    Publication Year: 2000, Page(s):432 - 435
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (2505 KB)

    The chemical composition and microstructure of a biocompatible material prepared from chitosan were evaluated using FTIR and SEM techniques. Its mechanical and physical properties were also tested. The materials nerve cell affinity and peripheral nerve repair feasibility were also evaluated. In vitro cytotoxicity tests indicated that both cerebral cortex cells and endothelial cells ECs can attach ... View full abstract»

    Open Access
  • Direct promotion of collagen calcification by alkaline phosphatase

    Publication Year: 2000, Page(s):436 - 438
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (680 KB)

    Alkaline phosphatase promotes hydrolysis of phosphate containing substrates causes a rise in inorganic phosphate and therefore enhances calcification of biological tissues. In this work the calcification of collagen in a model serum was used as a model of collagenous tissue biomaterials to study the possible calcification promotion mechanism of alkaline phosphatase. In the enzyme concentration ran... View full abstract»

    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.

Full Aims & Scope

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