Showing papers by "University of Electronic Science and Technology of China published in 1998"
TL;DR: A sufficient condition related to the existence of unique equilibrium point and its robust stability is derived and a novel interval dynamic Hopfield neural network (IDHNN) model is derived.
Abstract: The conventional Hopfield neural network with time delay is intervalized to consider the bounded effect of deviation of network parameters and perturbations yielding a novel interval dynamic Hopfield neural network (IDHNN) model. A sufficient condition related to the existence of unique equilibrium point and its robust stability is derived.
275 citations
TL;DR: In this paper, axonal signal transmission delay is introduced into BAM model yielding a class of generalized BAM networks, which have leading significance in the design and application of B AM networks.
Abstract: Bi-directional associative memory models are two-layer heteroassociative networks. In this paper, axonal signal transmission delay is introduced into BAM model yielding a class of generalized BAM networks. Conditions for the existence of equilibrium points, boundedness of trajectories and global stability are emphatically discussed for BAM with above-mentioned time delay. Circuit architecture of BAM with time delay is given. Correctness for our results is verified by using some examples and computer simulations. The obtained results have leading significance in the design and application of BAM networks. © 1998 John Wiley & Sons, Ltd.
173 citations
TL;DR: The Composite Buffer layer (CB-layer for short) as mentioned in this paper is a voltage-sustaining layer for power devices, which consists of alternating n- and p-type regions that are parallel to the direction of the applied electric field.
110 citations
TL;DR: An overview of various different ways of running IP across an ATM network and an assessment on these proposed schemes are given.
28 citations
TL;DR: In this paper, the numerical analysis is made to compare the DBIM and the Born iterative method (BIM), and a hybrid BIM is presented to improve the solution stability in later iterations.
Abstract: With its fast convergence, the distorted Born iterative method (DBIM) has been widely used in low-frequencg inverse scattering analysis, however its inherent drawback, sensitive-to-noise disturbance, may greatly limit its practical applications. In this paper, the numerical analysis is made to compare the DBIM and the Born iterative method (BIM). Then a hybrid BIM is presented. In this method, the DBIM is employed to speed the solution convergence in the initial several iterations and the BIM is used to improve the solution stability in the later iterations. The switch condition is also given. The simulation results show that the method is valid for the inverse scattering solution.
20 citations
15 Jul 1998
TL;DR: This paper presents the framework for representing the patterns and a set of mechanisms for navigating within the repository of patterns in a WWW environment.
Abstract: This work addresses the issues of defining (a) the structure of a knowledge repository of good business practices for managing change in organisations and (b) a Web based tool for providing a simple means for accessing this knowledge. Following the proposal made within the ESPRIT project ELEKTRA*, the expression of best business practices is done in terms of generic patterns. The term ‘pattern’ refers to such knowledge that may be repeatable from one situation to another, and shareable by many different users. The knowledge encapsulated in patterns is expressed in terms of the concepts of the EKD methodology (Enterprise Knowledge Development) such as enterprise goals, enterprise processes etc.. This paper presents the framework for representing the patterns and a set of mechanisms for navigating within the repository of patterns in a WWW environment.
10 citations
TL;DR: In this article, the authors studied the stability of matrices using technologies of special matrices analysis and obtained simple criteria for the stability for the matrix A=(aij)∈Cn×n, which is not diagonally dominant, by aid of simple algebraic conditions of aij only.
9 citations
8 citations
TL;DR: In this paper, a new kind of YAG (yttrium aluminum garnet) phosphor screen for projection cathode ray tubes is reported, which is fabricated by depositing phosphor powder on a YAG faceplate.
Abstract: A new kind of YAG (yttrium aluminum garnet) phosphor screen for projection cathode ray tubes is reported. The 3 in YAG phosphor screen is fabricated by depositing phosphor powder on a YAG faceplate. Owing to the YAG characteristic of higher heat conductivity than the conventional glass faceplate, the YAG phosphor screen obtains very high brightness, good contrast ratio and high resolution, and hence realises large-screen projection displays.
8 citations
TL;DR: In this article, a high-power x-band coaxial relativistic backward wave oscillator has been conceptually designed and analyzed, and the TMon dispersion relations in the coaxial corrugated cylindrical waveguide used in the device was calculated.
Abstract: A high-power x-band coaxial relativistic backward wave oscillator has been conceptually designed and analyzed. The TMon dispersion relations in the coaxial corrugated cylindrical waveguide used in the device was calculated. MAGIC,an electronmagnetic particle-in-cell code, is being used to investigated the nonlinear beam-wave interaction and other design optimization issues. Preliminary simulation results shows that the coaxial BWO can generate 2. 2 GW peak power microwave at 10. 15GHz in the TM02 mode driven by a 600-KV 20-KA electron beam, the peak power efficiency is about 18%.
8 citations
TL;DR: In this article, the authors derived the electrostatic energy of a charged rectangular coaxial line by transforming the field area by conformal mapping method and employing the principle of virtual work and the elliptic integrals.
01 Oct 1998
TL;DR: In this paper, the dispersion equation and interaction impedance of the ridge-loaded ring-plane slow-wave structure are obtained, by application of the Ritz-Galerkin method.
Abstract: The dispersion equation and interaction impedance of the ridge-loaded ring-plane slow-wave structure are obtained, by application of the Ritz-Galerkin method. Numerical results are given in terms of k-/spl nu//sub p/ curves and impedance diagrams. The influence of several geometrical dimensions on the dispersion characteristic and interaction impedance are discussed. This kind of slow-wave circuit can operate at a high power level over a relatively wide microwave-frequency range. To get higher power and broader bandwidth for this circuit the optimum opening angle and a smaller radius of the loaded ridge must be chosen. The paper provides the theoretical basis for designing this type of slow-wave circuit for high-power travelling-wave tubes.
TL;DR: In this article, a method for estimating the terrain height of interferometric synthetic aperture radar is proposed, where errors in height estimation due to the curvature of the Earth's surface are analysed and simulated.
Abstract: A method for estimating the terrain height of interferometric synthetic aperture radar is proposed. Errors in height estimation due to the curvature of the Earth's surface are analysed and simulated. By using L band SIR-C data for the ‘Three-Gorge’ area in China, the terrain height is obtained by employing the method. A method for estimating the parameters of the baseline is also presented. Simulations show that, under certain conditions, good results can be obtained.
21 Apr 1998-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The experimental results of the Smith-Purcell free-electron maser (orotron) developed at University of Electronic Science and Technology of China (UESTC) were reported in this article.
Abstract: This paper reports the experimental results of the Smith–Purcell free-electron maser (orotron) developed at University of Electronic Science and Technology of China (UESTC). The output powers from this FEM are 200 and 1200 mw, respectively, at 3 and 4 mm wavelengths.
TL;DR: In this article, the authors experimentally demonstrated the possibility of measuring refraction distribution in nonhomogeneous translucent objects using Shack-Hartmann sensors using holographic micro-lens matrix of 13 X 19 lenses with diameter 0.5 mm and focal length 80 mm.
Abstract: Possibility is experimentally demonstrated of measuring refraction distribution in non-homogeneous translucent objects using Shack-Hartmann sensors. Holographic micro-lens matrix of 13 X 19 lenses with diameter 0.5 mm and focal length 80 mm operating with simple market available CCD array resulted in the sensitivity to wave front measurements corresponding to 0.01 (lambda) .
TL;DR: In this paper, the authors applied the finite difference time domain (FDTD) method to the full-wave analyses of the electrical properties of millimeter wave coaxial to waveguide adapters.
Abstract: The finite-difference time-domain (FDTD) method is applied to the full-wave analyses of the electrical properties of millimeter wave coaxial to waveguide adapters. The results are useful for the design of wideband coaxial to waveguide adapter.
TL;DR: In this article, the approximate and much simple matching method of the fields of the half-circular structure of the helical groove structure is presented, and the more general expressions of the dispersion characteristic and coupling impedence, in which the fastwave modes and slow-wave modes are considered simultaneously, are obtained.
Abstract: As a new type all-metal slow-wave structure of the millimeter wave TWT, The helical groove has a lot of advantages: large power handling capability, large sizes, high precision and moderate bandwidth. Of the helical groove structure, the half-circular helical groove can achieve wider passband than the rectangular helical groove can do. The approximate and much simple matching method of the fields of the half-circular structure is presented in this paper. The more general expressions of the dispersion characteristic and coupling impedence, in which the fast-wave modes and slow-wave modes are considered simultaneously, are obtained. It is indicated from the results of the numerical calculation that choosing suitable dimensions of the structure and suppessing the backward wave osillation, this kind of slow-wave structure can operate over 50% ‘hot’ relative bandwidth.
TL;DR: In this paper, the power transmission problem of a coaxial line probe-to-circular waveguide for TM 0n multimodal excitation is rigorously treated using the conservation of complex power technique.
Abstract: The power transmission problem of a coaxial line probe-to-circular waveguide for TM0n multimodal excitation is rigorously treated using the conservation of complex power technique. The overall scattering matrix of the coaxial line probe-circular waveguide is deduced. Computed results for the reflection coefficient of the coaxial line probe are then compared with the experimental results, and they agree well. The power distribution of various order modes excited in a circular waveguide is investigated as a function of the probe length. Analysis shows that the power of the highest order TM0n propagation mode excited in the circular waveguide is usually the largest. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 19: 225–227, 1998.
TL;DR: In this paper, the normal modes in overmoded plasma waveguide coated with a lossy material are analyzed, particularly for the variation of its propagation properties with plasma parameters, coating materials, dimensions of the waveguide and frequencies.
Abstract: The normal modes in overmoded plasma waveguide coated with a lossy material are analyzed, particularly for the variation of its propagation properties with plasma parameters, coating materials, dimensions of the waveguide and frequencies. The separate characteristic equations of normal modes are derived, and their relevant approximate solutions are given. The limit results are consistent with those given in literature. The analysis shows that the propagation properties of the overmoded plasma circular waveguide can be controlled by choosing proper plasma parameters, coating materials and waveguide dimensions.
01 Jan 1998
TL;DR: In this article, a gas-filled free-electron laser pumped by a relativistic backward-wave oscillator without magnetic field was used for experiments with argon pressure between 2.3 mTorr to 15mTorr.
Abstract: Experimental studies of a gas-filled free-electron laser pumped by a relativistic backward-wave oscillator without magnetic field were performed. Radiation power from FEL and BWO both were observed for argon pressure between 2.3 mTorr to 15 mTorr, with maximum power at 5.3 mTorr. Theoretical studies of the radiation mechanism are underway.
TL;DR: In this article, a simple method using the magnetic vector potential to directly analyse a radial-line/coaxial-line junction is presented, where the admittance of the junction as seen from the coaxial line is obtained by the TEM approximation where the radial line is perfectly matched.
Abstract: A simple method using the magnetic vector potential to directly analyse a radial-line/coaxial-line junction is presented. The admittance of the junction as seen from the coaxial line is obtained by the TEM approximation where the radial line is perfectly matched. The result is equivalent to previously published results.
TL;DR: The results illustrate that the delay performance of the CBR services is satisfactory in the ATM DQDB MAN if the network is not overloaded seriously.
15 Jul 1998
TL;DR: The Diagram Markup Language (DML) is designed for describing the structure of diagrams, and a tool is implemented, called Diagram Drawer&Browser (DD&B), for supporting visual information processing on the WWW.
Abstract: Diagram techniques are widely used in visual information processing, hyperlink mechanism used successful in HTML can flexibly link related information, and Java applets can dynamically put diagram into Web pages that makes Web applications with more lively visual display. By combining these three techniques, we have designed the Diagram Markup Language (DML) for describing the structure of diagrams, and implemented a tool, called Diagram Drawer&Browser (DD&B), for supporting visual information processing on the WWW. This paper presents the implementation of DD&B, introduces the DML, and gives an application example.
TL;DR: In this article, a new transformation of modified Bessel function is built in order to integrate it, then a general integral formula involving the products two terms, each of them can be expressed a sum of any two modified bessel functions, is obtained by means of applying a theorem on calculus to this transformation smartly.
Abstract: In the evaluation of the power flow in some millimeter RF structures, a new kind of integrals of the type \(\int {^r } [A\zeta _
u (kr) + B\zeta _{ -
u } (kr)][A'\zeta _
u (kr) + B'\zeta _{ -
u } (kr)]\frac{{dr}}{r},\) in which ζ±ν(kr) denotes arbitrary Bessel functions of real order ±ν, is met. In order to integrate it, a new transformation of modified Bessel function is build in this paper: then a general integral formula involving the products two terms, each of them can be expressed a sum of any two modified Bessel function, is obtained by means of applying a theorem on calculus to this transformation smartly, Furthermore, making use of the characteristics of modified Bessel function and the definition of Bessel function, the analytical expression of the above integral is derived.
01 Jan 1998
TL;DR: In this paper, the superposition and splitting characteristics of fields in rectangular stepped waveguide are analyzed with the way of matched field by using numerical method, the relationship between distribution of fields and the transmission distance is studied.
Abstract: The superposition and splitting characteristics of fields in rectangular stepped waveguide are analyzed with the way of matched field. By using numerical method, the relationship between distribution of fields and the transmission distance is studied. And the process of one TE10 wave beam splitting to two is modeled by computer. The theoretical results not only are useful for devising relevant devices, but also offer preparation for further work in studying FEM system in China.
TL;DR: In this paper, the effect of the Miniature Stirling Cooler on the noise of a photo-voltaic QD has been investigated and the results showed that the Stirling cooler will cause additionalnoises to the QD it cooled, but the increasing noise can be reduced if some means are taken.
Abstract: In this paper, an experimental research on the effect of the Miniature Stirling cooler on the noise of a photo-voltaic QD hasbeen fulfilled. Based on strictly implements, the noise power spectrum densities of the QD under Stirling cooling have beenmeasured and compared with that of Liquid N2 cooling. The results showed that the Stirling Cooler will cause additionalnoises to the QD it cooled, but the increasing noise can be reduced if some means are taken.Key words noise power spectrum density, Miniature Stirling cooler, photo-voltaic QD, Stirling cooler/infrared detectorassembly 1. INTRODUCTION Infrared detectors have gotten wide applications in the optical systems such. as thermal imaging, laser communications, laser radar and laser distance measurement et al. Many high performance detectors, especially those worked in the long wavelength, are needed to be deep cooled. There are many methods to cool the detectors, such as Liquid N2 cooling, J-Tcooling, they all inconvenient for the engineering application. In the resent years, Miniature Stirling cooler has gotten themost extensive uses in the field of infrared systems for its advantages of high thermal efficiency, light weight, simpleoperation and wide range of cooling temperatureE'H4]. In some applications, the coolers have been assembled with somekinds of infrared detector and formed matured assemblies as the one used in this work.However, Stirling cooler has two main disadvantages in infrared applications. Firstly, as a kind of mechanical cooler, itcauses vibration; Secondly, the compressor contains electro-magnetic elements such as engine, temperature control circuitand position sensor, they may induce alter-electromagnetic radiation. Those two factors will surely increase the noises of thedetectors mounted on the cold finger as well as the system, thus degenerate the performance ofthe infrared detection systems.This has been a serious problem to infrared engineers for years long, and it has verified by our resent experiments.Commonly, Liquid N2 has been the most convenient cooling method in the laboratory and has little influence to the detectorsand systems it cooled, in spite of its inconvenience in engineering applications. So, in this paper, we compared the noisepower spectrum density of the photo-voltalc QD cooled by Stirling cooler with that of cooled by Liquid N2 to study theeffects that Stirling cooler done to the detector.In our previous publications61171, we have presented the Noise effects of miniature Stirling cooler on the infrared detectors asSPRITE and multi-elements conductive detectors. In this paper, we will further study the noise effects of Stirling cooler on a
03 Nov 1998
TL;DR: In this article, the authors reported the thermal blooming effect induced by a group of water particles absorbing energy of CW Ar+ laser propagating, which is induced by an aerosol box, some right-angle-reflectors, and some water droplets in the box.
Abstract: In propagation of high power laser through atmosphere, the affection to thermal blooming by aerosol is a research field. Thispaper reports the experiment result of thermal blooming effect, which is induced by a group of water particle absorbingenergy of CW Ar+ laser propagating. Our system includesan aerosol box, some right-angle-reflectors. By mean of increasingof the absorption of the particle, we observed the thermal blooming phenomenon of laser interacting with aerosol. When thedensity of droplet in the box increases, the laser beam outputting from the box moves down. And the size at the verticaldirection becomes small because of the convection of air heated by the aerosol absorbing laser energy. When the density ofparticles decreases, the beam will go back to the initial location. The experiment shows that aerosol can induce the thermalblooming of high power laser.Key Words: thermal blooming, aerosol, laser, Ar+, beam 1. INTRODUCTION When the laser beam propagates through the atmosphere, especially near the ground, the affection of aerosol is a mostimportant factor influencing the quality ofpropagating laser. Aerosol will absorb and scatter laser energy. When the power oflaser is high enough, the particle will get a lot of heat energy, and its temperature will rise higher. Because heat transfereffect of conduction of air exists, the heat energy will be transfer into air from the particle, and air will be heated. Then laserwill be influence by air heated. The shape and the direction of laser beam will change. And the thermal blooming action isformed, which is similar to the gas absorption. In order to describe this effect induced by aerosol, the effective absorptioncoefficient of aerosol 1,2,3,4 is used, and the scattering cross-section of air heated by absorbing particle is calculated5'6.