Showing papers by "University of Electronic Science and Technology of China published in 1993"
TL;DR: In this paper, the authors considered the transient scattering of an electrically polarized, two-dimensional, pulsed wave by a two-dimensionally inhomogeneous, lossy dielectric cylinder embedded in free space.
Abstract: We consider the transient scattering of an electrically polarized, two-dimensional, pulsed wave by a two-dimensionally inhomogeneous, lossy dielectric cylinder embedded in free space. The problem is formulated in terms of a contrast-source domain integral equation over the interior of the cylinder. This integral equation is solved numerically, with the aid of the "marching-on-in-frequency" method recently proposed in [1]. To this end, a new discretization procedure is introduced, which is more accurate than the usual piecewise-constant moment-method approach. This discretization preserves the convolution-type structure of the continuous equation, which enables the repeated application of the "conjugate-gradient FFT" method. The initial estimates required in this method are generated by marching on in frequency, using a special extrapolation scheme. Numerical results are presented and compared with the results obtained by applying alternative techniques.
38 citations
TL;DR: In this article, the target erosion pattern was studied by the symmetrical magnet magnetron sputtering method and three cathodes with different inner magnets were used respectively, and the results showed that the target erasure pattern had a close relationship with the magnetic field distribution.
16 citations
TL;DR: In this article, a spherical wave function theory for bounded homogeneous elastic anisotropic media is developed, which is solved exactly by using the method of plane-wave angular spectrum expansions.
Abstract: A spherical-wave-function theory of bounded homogeneous elastic anisotropic media is developed. The anisotropic elastodynamic wave equations are solved exactly by using the method of plane-wave angular spectrum expansions. The series, integral representations, and addition theorems of the spherical wave functions of the first, second, third, and fourth kind for homogeneous elastic anisotropic media (HEAM) are presented. Weyl's method for the scalar Green's functions in isotropic media is generalized to the study of the dyadic Green's functions in HEAM. The series representations of Green's functions are of the form of separated variables. These representations are well suited to imposing a boundary condition when dealing with waves in spherically layered HEAM.
9 citations
TL;DR: In this article, an analysis of a thin wraparound microstrip antenna is presented, based on the cavity model and the equivalence principle, where formulas for the far zone electric field are obtained by considering the equivalent magnetic current radiation in the presence of a cylindrical surface.
Abstract: An analysis of a thin wraparound microstrip antenna is presented. Based on the cavity model and the equivalence principle, formulas for the far zone electric field are obtained by considering the equivalent magnetic current radiation in the presence of a cylindrical surface. The radiation patterns for the TM/sub 01/ mode are in agreement with other results. However, its formula is much more compact than the others. Finally, numerical results are given to illustrate the effect of curvature on the radiation patterns. >
8 citations
TL;DR: In this article, a new type of cathode-sputtering apparatus with one inner annular magnet and two outer annular magnets facing each other has been developed, which not only deposit films at high rate but also greatly improve the target utilization.
7 citations
TL;DR: An expression of the RCS of a partially coated scatterer to evaluate the effects of absorbent materials and the deviation from physical similarity between models and prototype for lack of requiring absorbent material in model testing has been given as discussed by the authors.
Abstract: An expression of the RCS of a partially coated scatterer to evaluate the effects of absorbent materials and the deviation from physical similarity between models and prototype for lack of requiring absorbent materials in model testing has been given. A comparison between theoretical and experimental values for a conducting cylinder partially coated with absorbent materials has shown good agreement. © 1993 John Wiley & sons, Inc.
6 citations
TL;DR: Riblet's rectangular line with off-center strip inner conductor is changed into one with a vertically sliding symmetrical cross as an inner conductor as mentioned in this paper, which is a modification of the line with a rectilinear inner conductor.
Abstract: Riblet's rectangular line with off-center strip inner conductor is changed into one with a vertically sliding symmetrical cross as an inner conductor. © 1993 John Wiley & sons, Inc.
5 citations
TL;DR: In this paper, the capacitance of an insulated conductor of arbitrary shape is calculated using very simple mathematics, and simple but accurate enough formulas are found to calculate the capacitation of the conductor.
Abstract: This article will employ very simple mathematics to calculate the capacitance of an insulated conductor of arbitrary shape. Simple but accurate enough formulas are found. As examples, three cases are given in this article. © 1993 John Wiley & sons, Inc.
5 citations
01 Jan 1993
TL;DR: In this paper, the theoretical problems of gyrotron pump for free electron laser with electro-magnetic wiggler (EMW-FEL) are studied, such as the azimuthal polarization of EMW, and the relation between the transient properties of gyroron and the working conditions.
Abstract: Some theoretic problems of gyrotron pump for free electron laser with electro- magnetic wiggler(EMW-FEL)are studied,such as the azimuthal polarization of EMW,and the relation between the transient properties of gyrotron and the working conditions.These prob- lems make a remarkable influence on EMW-FEL system.In this paper,the numerical calcula- tions and analysis are given for TE_13 mode.
4 citations
28 Jun 1993
TL;DR: In this article, the eigenvalues are expressed explicitly in terms of the mutual coupling and correlation coefficient in the presence of two sources, and simulation shows that mutual coupling between elements improves the adaptive array's eigenvalue behavior.
Abstract: In adaptive arrays using control loops, the rate of convergence is governed by eigenvalues of the covariance matrix. In cases where the eigenvalues are widely different, the convergence is very slow. In the present work, the eigenvalues are expressed explicitly in terms of the mutual coupling and correlation coefficient in the presence of two sources. Simulation shows that the mutual coupling between elements improves the eigenvalue behavior, and that the improvement is maximum for the adaptive array with about half-wavelength spacing. >
4 citations
TL;DR: In this article, a reverse-time migration method for elastic wave imaging was developed based on the one-way method for acoustic waves and a newly derived separation formula for transverse and longitudinal waves.
Abstract: SUMMARY A one-way reverse-time migration method is developed for elastic wave imaging in this paper. It is based on the one-way method for acoustic waves and a newly derived separation formula for transverse and longitudinal waves. Numerical experiments confirm the efficiency of the method.
TL;DR: In this paper, the authors derived the formulas of harmonic spontaneous emission power density, small-signal gain of this new type of undulator free-electron laser and the coupling coefficient between electrons and radiation field.
12 Feb 1993
TL;DR: In this paper, a 40K X 8 bit pixels/sec diode laser imaging system was authenticated by specialists last year, and the performance comparison of receiving is evaluated for detection type and operation state.
Abstract: Diode laser imaging is one of the advanced sensors. It is best suited for the aerospace flight environment. We have developed a 40K X 8 bit pixels/sec diode laser imaging system, and this system was authenticated by specialists last year. This paper describes several important problems for intensity imaging which include improving laser power utilization ratio and receiving sensitivity in a laser imaging system. Improvement SNR of an imaging system is a criterion of analysis and comparison. Waveform design of both the maximum power limited and average power invariant are analyzed separately. In order to understand avalanche gain contribution to receiver SNR, performance comparison of receiving is evaluated for detection type and operation state. The comparison includes intensity modulated (IM)/coherent detection (CD) and IM/Direct detection (DD) for different avalanche gain values and different photodetector load resistance values. According to the relations between receivable return power and SNR, a series of curves are calculated by computer. These curves clearly show the best detecting type for various receiver power levels. These results of analyses provide the theoretical basis of transmitter and high sensitivity receiver design. These analyses also show that in intensity imaging system correct waveform selection can make 4 dB improvement on SNR and reasonable receive trade-off design can make about 30 dB improvement on SNR.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this paper, the scale factor q2 is not always proportional to the geometrical scale factor p2, but to p to the powers of 2-4 for a variety of shaped scatterers, provided their characteristic dimensions are much greater than the working wavelength.
Abstract: For scale-model measurement of the RCS of a lossy target, it is difficult to meet all the requirements of physical similarity [1], especially in the constitutive parameters of the absorbent materials because of their frequency dependence. One often avoids this problem by keeping the wavelength of incident radiation fixed with the sizes of the target scaled down. In this case, the scale factor to evaluate the RCS of prototype from that of a scale model must be found. This article gives brief expressions of the RCS and the scale factors for simply shaped scatterers by means of a PO approximation and the method of stationary phase. It is found that the physical scale factor q2 is not always proportional to the geometrical scale factor p2, but to p to the powers of 2-4 for a variety of shaped scatterers, respectively, provided their characteristic dimensions are much greater than the working wavelength. © 1993 John Wiley & sons, Inc.
TL;DR: In this paper, a CARM oscillator with axisymmetrical quasi-optical cavity of oblique rotation at arbitrary angle (AQCORAA) was studied using the kinetic theory.
Abstract: A novel CARM oscillator with axisymmetrical quasi—optical cavity of oblique rotation at arbitrary angle (AQCORAA) is studied using the kinetic theory. By means of the method of local field expansion in the coordinates of the guiding centre and the Laplace transform, the beam—wave interaction power, starting current density and frequency shift are derived. The formulas presented here may have some potential applications for more further studies of the CARM oscillator with AQCORAA.
TL;DR: In this paper, the authors extended the complex ray theory from lossless media into lossy ones and used it in the problems of scattering analysis of objects coated with radar absorbing materials (RAM).
Abstract: With the extension of complex ray theory (CRT) from lossless media into lossy ones, the complex ray analysis in lossy media can be constructed and effectively used in the problems of scattering analysis of objects coated with radar absorbing materials (RAM). This method has some advantages, such as simple calculation procedure, clear physical meaning, wide application area etc. As an example, the radar cross-section (RCS) of conducting flat plates coated with RAM is analyzed. The results show that the theoretical predictions agree very well with the experimental results.
TL;DR: The analytical expressions and the numerical results for the scattering coefficients and the even-odd mode conversion coefficients of the guided modes are given, based on the method of dyadic Green's functions and on the expansions of the modal fields in terms of the vector cylindrical wave functions.
Abstract: By considering active molecules or ions as a collection of induced oscillating dipoles, we treat the problem of Raman or fluorescent scattering by the active molecules or ions embedded in a single-mode optical fiber theoretically. The analytical expressions and the numerical results for the scattering coefficients and the even–odd mode conversion coefficients of the guided modes are given, based on the method of dyadic Green's functions and on the expansions of the modal fields in terms of the vector cylindrical wave functions. We expect to incorporate the treatments into the analysis of a rare-earth-doped fiber amplifier or a fiber Raman amplifier.
TL;DR: An automatic measurement system for the magnitude and orientation of displacement is developed and an image processing method for double-exposure speckle patterns including Speckle noise filtering and fringe center-line extraction is presented.
Abstract: This paper presents an image processing method for double-exposure speckle patterns including speckle noise filtering and fringe center-line extraction. Based on the implementation of this method and basic image processing, an automatic measurement system for the magnitude and orientation of displacement is developed.
TL;DR: From a coincidence theorem in [1] there are derived some interesting applications to many respects such as minimax inequality, fixed point theory, existence of minimizable quasiconvex functions, etc..
Abstract: From a coincidence theorem in [1] there are derived some interesting applications to many respects such as minimax inequality, fixed point theory, existence of minimizable quasiconvex functions, etc..
TL;DR: In this paper, the higher harmonics of the free electron laser (FEL) with a two-wavenumber plane wiggler magnetic field, which may induce a lot of high harmonics, are investigated.
Abstract: The higher harmonics of the free electron laser (FEL) with a two-wavenumber plane wiggler magnetic field, which may induce a lot of higher harmonics, are investigated. Using a two-wavenumber wiggler comprised of two separate periodicities, kw and kw + Δk, numerical simulations show that the higher harmonic may be amplified and the first harmonic may be suppressed in this kind of FEL with an optimized parameter Δk. The coupling coefficient and gain coefficient in low-gain regime of the harmonic are also obtained.
TL;DR: In this paper, an approximate formulation for the scattering response of a biani-sotropk spheroid in the presence of a perfectly electrical conducting (PEC) plane is presented using image theory for bianisotropic bodies.
Abstract: An approximate formulation for the scattering response of a biani-sotropk spheroid in the presence of a perfectly electrical conducting (PEC) plane is presented using image theory for bianisotropic bodies. It is revealed that cross-polarization and copolarization phenomena may occur for certain constitutive parameters, respectively or simultaneously. © 1993 John Wiley & Sons, Inc.
TL;DR: In this paper, a five-channel grating spectrometer for use in millimeter wave band (25∼100GHz) is described with its design theory of optical path, and measured results of insertion loss and resolving power.
Abstract: A five-channel grating spectrometer for use in millimeter wave band (25∼100GHz) is described with its design theory of optical path, and measured results of insertion loss and resolving power.
Journal Article•
TL;DR: In this paper, a hew method to analyse the mode of axially-asymmetric optical resonators is proposed, where the algebraic equations for the sizes and the locations of the beam waists of the ellipse Gaussian beam, as well as the stability condition are obtained.
Abstract: A hew method to analyse the mode of axially-asymmetric optical resonators is proposed. The algebraic equations for the sizes and the locations of the beam waists of the ellipse Gaussian beam, as well as the stability condition are obtained. This method has the advantages of simple, easy and universal validity.
TL;DR: In this article, the AIN films were prepared with a new four-pair facing target type sputtering method at a low substrate temperature, and the deposition rate was about 140 A min −.
TL;DR: In this article, the characteristics of a cavity-backed slot antenna in a lossy medium were given by using the moment method and Dyadic Green's function, and the Poisson summation formula was used to convert the double series of the elements into a more rapidly converging series.
Abstract: The characteristics of a cavity-backed slot antenna in a lossy medium are given by using the moment method and Dyadic Green’s function. The Poisson’s summation formula is used to convert the double series of the elements into a more rapidly converging series, and the integration middle value theorem and elliptic integral are used to simplify the double integral of the elements. Numerical results show the effects of the lossy medium and antenna parameters on the input impedance, which could be used in designing the cavity-backed slot antenna.
15 Oct 1993
TL;DR: In this article, a 10.6m wavelength laser incident on a bulk germanium sample was found to affect the conductivity of the germania, which is attributed to a ultrasonic field excited by change of laser power.
Abstract: The experiment found that 10. 6im wavelength laser incident on a bulk germanium affectsconductivity of germanium. The change of conductivity is ascribed to a ultrasonic field excited bychange of laser power , which scatters carriers in semiconductor and results in a chagne of con—ductivity. Relative change of conductivity X 1O is observed when laser power changes about 1 Watt . Application in mid-infrared laser detection is proposed and discussed. 1. INTRODUCTION In theory of electromagnetism , optic pressure has been stated. However , experimental researches aboutthis phenomenon have been hardly reported in literatures. It was only after laser invention that the effect wasused in research for laser controlled nuclearfusion. It should be employed in more techniques such as in detec-tion of mid-infrared laser. For this range of spectrum, a semiconducting detector based on quantum transitionmust be cooled to a very low temperature. Development of 10. 6m laser radar and free space communication,for examble, are restricted by liquid nitrogen cooled detector. Mechanism of optic pressure should be indepen-dent on wavelength of laser and can operate in room temperature. It relates only to intensity of laser. Further-
11 May 1993
TL;DR: In this article, the Stokes field of a high-power laser was analyzed and the gain expression of the field was shown to decrease as the number of pulses increases, indicating that the memory effect is the most important factor, influencing the gain of Stokes fields.
Abstract: In the transient interaction between the laser and the material, because of the medium memory effect, the transient response of the stimulated Raman scattering (SRS) to the pulse train of high power laser is different from the effect of the single pulse. This paper discusses the SRS of the pulse laser. The gain expression of Stokes field is given. It can be seen that as the interval T increases, the Stokes's gain decrease. When the pulse number N is large enough, the gain of the Stokes pulse arrives at the steady-state value. The memory effect is the most important fact, influencing the gain of the Stokes field. At the edge of each pulse there is the Stokes field.
TL;DR: In this article, a novel multiconductor elliptic cone microstrip lines were rigorously analyzed under the assumption of quasi-TEM mode and the Maxwell's capacitance matrix and characteristic impedance matrix were determined using the method of coordinates trnasformation and conformal mapping.
Abstract: A Novel multiconductor elliptic cone microstrip lines are rigorously analyzed under the assumption of quasi-TEM mode. The Maxwell's capacitance matrix and characteristic impedance matrix are determined using the method of coordinates trnasformation and conformal mapping
TL;DR: In this paper, an analysis for electromagnetic response of a PEC of spherical shape having an uniform concentrical coating of biisotropic medium is rigorously formulated by constructing spherical vector wavefunctions.
Abstract: An analysis for electromagnetic response of a PEC of spherical shape having an uniform concentrical coating of biisotropic medium is rigorously formulated by constructing spherical vector wavefunctions. For the prescribed radius and thickness of the coating, an anisotropic impedance boundary condition at the outer surface of the coating is developed in the spectral domain, which is useful for solving the scattering problem of the biisotropically coated spherical PEC structure.
TL;DR: In this article, a number of existence theorems on simultaneous solutions to fixed point and minimax-type inequality problems and to variational-type inequalities are given. But these results are still simpler in form with simpler proofs.
Abstract: As important applications of minimax-type inequalities for a family of functions in [3], in the present paper there are given a number of existence theorems on simultaneous solutions to fixed point and minimax-type inequality problems and to fixed point and variational-type inequality problems, not only abolishing the paracompactness hypothesis on the underlying space and weakening the others in the results in [1], but also making them still nicer in form with still more concise and straightforward proofs.