Showing papers by "University of Electronic Science and Technology of China published in 1989"
01 Jun 1989
TL;DR: The main details of a series of computer programs to implement an optimum design of the E-field distribution are presented in this paper, where the characteristic impedance and electric field are obtained for an asymmetric TEM cell.
Abstract: By using the Green's function/variational formulation with a new form of charge distribution, expressions for the characteristic impedance and electric (E-) field are obtained for an asymmetric TEM cell. The main details of a series of computer programs to implement an optimum design of the E-field distribution are presented in this paper.
35 citations
TL;DR: In this article, the buck resonant switching converter is investigated by use of a new time-averaging equivalent circuit analysis method presented recently by the authors, without a prior knowledge of the d.c. analysis and a.c, small-signal analysis.
Abstract: The sophisticated resonant switching converter is investigated by use of a new time-averaging equivalent circuit analysis method presented recently by the authors. The parameters of the time-averaging equivalent circuit model can easily be determined by the new approach without a prior knowledge of the d.c. solution for the converter. The d.c. analysis and a.c, small-signal analysis can then be performed based on the time-averaging equivalent circuit model. Design formulae for the buck resonant converter together with a numerical approximation example are also given.
25 citations
08 May 1989
TL;DR: In this paper, the main theorem of the time-averaging equivalent circuit approach (ECA) for the modeling and analysis of switching DC-DC converters reported by the authors (1988 IEEE Int. Symp. on Circ., p.1139-42) is extended to include the case in which the condition f/sub s/>>f/sub 0/ is not satisfied.
Abstract: The main theorem of the time-averaging equivalent circuit approach (ECA) for the modeling and analysis of switching DC-DC converters reported by the authors (1988 IEEE Int. Symp. on Circ. Syst., p.1139-42) is extended to include the case in which the condition f/sub s/>>f/sub 0/ is not satisfied, where f/sub s/ is the switchup frequency and f/sub 0/ is the natural frequency. The results obtained by the extended ECA show that the DC-steady-state behavior of switching DC-DC converters is generally dependent on f/sub s/, whereas most of the existing methods for the modeling and analysis of switching DC-DC converters fail to give accurate results in this case. >
10 citations
TL;DR: In this paper, a few coincidence theorems and minimax theorem are given so as to unify and strengthen the corresponding results in [3], [4] and [5].
Abstract: In the present paper a few coincidence theorems and minimax theorems are given so as to unify and strengthen the corresponding results in [3], [4] and [5].
9 citations
TL;DR: In this article, a new theory for analysis of inelastic multiple scattering by active molecules embedded in randomly distributed spherical scatterers is developed, based on the theory of elastic multiple scattering.
Abstract: According to the model of equivalent dipoles for active molecules, the analysis of inelastic EM scattering by active molecules embedded in a sphere is given by the method of dyadic Green's functions at first and then, based on the theory of elastic multiple scattering by randomly distributed spherical scatterers which we have developed recently, a new theory for analysis of inelastic multiple scattering by active molecules embedded in randomly distributed spherical scatterers also is developed.
5 citations
TL;DR: Based on the exact scalar wave equations of bent slab waveguides, locally leaky-mode attenuation constants for both TE and TM modes are derived by using the WKB tunneling theory.
Abstract: Based on the exact scalar wave equations of bent slab waveguides, locally leaky-mode attenuation constants for both TE and TM modes are derived by using the WKB tunneling theory. Changes in propagation constant due to waveguide bending are considered in our calculation. Under some assumptions, our results are found to be identical to other results obtained using entirely different methods.
5 citations
TL;DR: In this paper, the perturbation effect of an incomplete spherical electrode in a uniform electrostatic field was exploited to solve the problem of microwave field problems with incomplete spherical electrodes, where the perturbing effect of the conducting body in the uniform electric field was utilized as on approximate solution.
Abstract: In some microwave field problems we have to utilize the perturbing effect of o conducting body in a uniform electrostatic field as on approximate solution. Here we solve one such problem of an incomplete spherical electrode in a uniform electrostatic field.
4 citations
TL;DR: In this article, an analysis on the dispersion relations and the distributions of the axial electric field components of the waveguide modes, which are important to determine the operating frequency and gain, has been carried out.
Abstract: Waveguides with inner dielectric cylinder(s) for Cerenkov free electron laser are presented. An analysis on the dispersion relations and the distributions of the axial electric field components of the waveguide modes, which are important to determine the operating frequency and gain, has been carried out. The results show that the waveguides can be employed to generate radiations at lower millimeter wavelength with higher gain and larger power output.
3 citations
10 Dec 1989-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: A brief survey of FEL activity in the People's Republic of China is given in this paper, where results obtained from a Raman type FEL are reported and experimental work on a Compton Type FEL is discussed.
Abstract: A brief survey of FEL activity in the People's Republic of China is given. Results obtained from a Raman type FEL are reported and experimental work on a Compton type FEL is discussed. Theoretical studies on the FEL have been carried out.
3 citations
TL;DR: The scalar local field equations are derived from the Maxwell's equation in a bent local coordinate system and the field transformation function for the TM (or the x-polarized) modes in this article.
Abstract: The scalar local field equations are derived from the Maxwell's equation in a bent local coordinate system, and the field transformation function for the TM (or the x-polarized) modes in our recent papers is corrected as well. It is found that no pure geometry birefringence can be produced if the gradient-index term of local field equations is neglected when the waveguide we considered is weakly guiding.
3 citations
TL;DR: The results show that CARM's and nonwiggler free-electron lasers may have higher conversion efficiency of electron-beam kinetic energy than ordinary gyrotrons.
Abstract: This paper derives in detail the Madey-theorem derivation for the gyrotron, the cyclotron autoresonance maser (CARM), and the nonwiggler free-electron laser with traveling-wave mode or standing-wave mode. The results show that CARM's and nonwiggler free-electron lasers may have higher conversion efficiency of electron-beam kinetic energy than ordinary gyrotrons.
19 Jun 1989
TL;DR: In this article, a brief report of both theoretical and experimental works of the electrostatic electron cyclotron resonance maser and electrostatic FEL in the ECC system is presented.
Abstract: This paper is a brief report of both theoretical and experimental works of the electrostatic electron cyclotron resonance maser and electrostatic FEL in the electrostatic centrifugal system, concerning mechanisms and some interesting phenomena.
TL;DR: In this article, a set of coupled equations for electron motion and the dispersion relation of electromagnetic wave (wiggler) in electron beam are studied and the instability of steady-state electron orbits is reduced to the problem of the fourth-order and fifth-order linear ordinary differential equations.
Abstract: A set of coupled equations for electron motion and the dispersion relation of electromagnetic wave (wiggler) in electron beam are studied. The instability of steady-state electron orbits is reduced to the problem of the fourth-order and fifth-order linear ordinary differential equations. It is found that the presence of self-fields plays an important role in determining the behaviour of stable electron orbits.
TL;DR: In this paper, a possible scheme to increase the bandwidth of an optical soliton communication system is proposed, where the split step method and the propagating beam method are equivalent and numerically calculated by the method that the initial equal separation first-order multipulse series propagates in an optical fiber.
Abstract: It is pointed out that the split step method and the propagating beam method are equivalent and numerically calculated by the method that the initial equal separation first-order multipulse series propagates in an optical fiber. A possible scheme to increase the bandwidth of an optical soliton communication system is proposed.
01 Oct 1989
TL;DR: A new method is presented to minimize array output power subject to linear functional inequatity constraints, which takes the frequency bandwidth into account, and has very good wideband performance.
Abstract: This paper presents a new method for the design of wideband array processors based on Semi-Infinite Quadratic Optimization techniques. The method is to minimize array output power subject to linear functional inequatity constraints, which takes the frequency bandwidth into account. Computer simulations and comparisons with Frost's array processors with presteering are given showing that the new method has very good wideband performance. It is also robust to various mismatches, a very desirable feature for implementation.
TL;DR: In this paper, the deformed anisotropic Heisenberg model suggested by Mikhailov and Shabat is discussed from the viewpoint of prolongation theory and the Lax pair associated with this equation is derived.
TL;DR: In this article, an effective dielectric parameter method having higher accuracy is introduced, and the agreement between experimental values and the values calculated by this method is shown to be quite good.
Abstract: The effective dielectric constant method is known for analyzing propagation characteristics of dielectric waveguides. In this paper we discuss the substance of this method. Further, an effective dielectric parameter method having higher accuracy is introduced. The agreement between experimental values and the values calculated by this method is shown to be quite good.
22 Dec 1989
TL;DR: In this article, a nonlinear simulation of the TE2,2,22 mode at the wave-length of 2 mm under the guide of several thousands gauss was presented, where the relativistic electron beam is guided by an axial magnetostatic field under the absence of wiggler.
Abstract: Nonlinear simulation of efficiency is given to the large-orbit non-wiggler free electron lasers,where the relativistic electron beam is guided by an axial magnetostatic field under the absence of wiggler. The influences of the initial parameters are discussed. It is found that 19% may be achieved for the efficiency of TE2,2,22 mode at the wave-length of 2 mm under the guide of several thousands gauss.
28 Aug 1989
TL;DR: In this article, the linear theory of free electron laser (FEL) is provided from the point of view of space-charge waves, and a new kind of hybrid FEL with a slow-wave circuit, which may enhance efficiency with the aid of coupling of the first space harmonic with the space charge wave is presented.
Abstract: The linear theory of free electron lasers (FELs) is provided from the point of view of space-charge waves. The basic equation describing the space-charge waves in FELs is derived and analyzed. A new kind of hybrid free electron laser with a slow-wave circuit, which may enhance efficiency with the aid of coupling of the first space harmonic with the space-charge wave, is presented.