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Showing papers by "University of Electronic Science and Technology of China published in 1999"


Journal ArticleDOI
TL;DR: In this article, the influence of a soliton on the properties of the Mossbauer effect resulting from the gamma-active nuclei situated at lattice sites in quasi-one-dimensional anharmonically organic molecular chains, in which the active nuclei emit gamma-photons, has been theoretically studied by a quantum vibrational model.
Abstract: The influence of a soliton on the properties of the Mossbauer effect resulting from the gamma-active nuclei situated at lattice sites in quasi-one-dimensional anharmonically organic molecular chains, in which the active nuclei emit gamma-photons, has been theoretically studied by a quantum vibrational model. An expression for the gamma-radiated Mossbauer transition probability as a function of the temperature and non-linear interaction has been obtained. Finally we give some new properties of this effect from numerical calculation in such a case, which present a way to experimentally confirm the soliton existence in molecular crystals.

38 citations


Journal ArticleDOI
01 Dec 1999-Polymer
TL;DR: The layer-by-layer self-assembly of polyaniline (PAN) and polyacrylic acid (PAA) has been accomplished via the alternate spontaneous adsorption of base-type PAN from its dilute N-methylpyrrolidinone solution and PAA from its aqueous solution as discussed by the authors.

30 citations


Journal ArticleDOI
TL;DR: In this article, a self consistent nonlinear theoretical model for a complex cavity gyrotron with abrupt transitions is presented, which accounts for mode conversion in the transition region of the complex cavity through the general theory of modal expansion techniques.
Abstract: A self consistent nonlinear theoretical model for a complex cavity gyrotron with abrupt transitions is presented in this paper. The model accounts for mode conversion in the transition region of the complex cavity through the general theory of modal expansion techniques. The interaction between the electron beam and TE/sub 61//TE/sub 62/ RF field in the step cavity for a third-harmonic gyrotron is simulated; many calculations are carried out under different electron beam parameters.

19 citations


Journal ArticleDOI
TL;DR: In this article, X-ray fluorescence spectrometry is applied to the determination of trace elements in fruit juice characterized by a high content of sugar and other soluble solid substances, and the synthesis of standards is described in detail.

19 citations


Journal ArticleDOI
TL;DR: In this article, a multipole theory (MT) method is presented for calculating two-dimensional (2-D) Helmholtz equation problems, and the general MT formula and its applied laws are derived.
Abstract: A new approach, the multipole theory (MT) method, is presented for calculating two-dimensional (2-D) Helmholtz equation problems. By the mathematical deduction, the general MT formula and its applied laws are derived. The new approach has been applied to compute the cutoff wavenumbers of a rectangular waveguide, as analytical results are available for this problem. In order to further verify the accuracy of this method, the MT method has also been applied to compute the TE and TM modes of two high power waveguides and a square offset line. Comparison of accuracy is made whenever data is available. It has been proven that the MT method is an effective approach for calculating 2-D Helmholtz equation problems.

17 citations


Journal ArticleDOI
01 Feb 1999
TL;DR: A method based on adaptive regularisation for range super-resolution that can simultaneously estimate the number and time delays of the overlapping echoes, whereas determining the number of echoes in ML-type algorithms is difficult is presented.
Abstract: A method based on adaptive regularisation for range super-resolution is presented. The method is computationally efficient and has low SNR threshold close to that of the maximum likelihood (ML) method. The method can simultaneously estimate the number and time delays of the overlapping echoes, whereas determining the number of echoes in ML-type algorithms is difficult. Numerical simulation results demonstrate the performance and show that the method is capable of simply and effectively achieving enhanced range resolution.

11 citations


Journal ArticleDOI
TL;DR: In this paper, a Cherenkov oscillator operating simultaneously at two different wave bands (3cm and 8mm) is described, and the measured output power is 10 MW at 3cm wave band, and 1MW at 8mm wave band.
Abstract: A Cherenkov oscillator operating simultaneously at two different wave bands (3cm and 8mm) is described in this paper. Experimental results from the oscillator are reported. The measured output power is 10 MW at 3cm wave band, and 1MW at 8mm wave band. The operating modes for BWO and R-orotion are E01 and E13, respectively.

10 citations


Journal ArticleDOI
TL;DR: A multilayer perceptron neural network (MLPNN) is used to model the gap discontinuities in stripline circuits, electromagnetically developed with a set of training data produced by the full-wave finite-difference time-domain (FDTD) method.
Abstract: Gap discontinuities appear in many stripline circuits, such as the multilayer microwave monolithic ICs and the interconnect systems in high-speed digital circuits. In this paper, a multilayer perceptron neural network (MLPNN) is used to model the gap discontinuities in stripline circuits. The MLPNN is electromagnetically developed with a set of training data that are produced by the full-wave finite-difference time-domain (FDTD) method. The full-factor design of experiments is used for determining the size of the training data.

9 citations


Journal ArticleDOI
01 Apr 1999
TL;DR: In this paper, a voltage-sustaining structure with embedded oppositely doped islands is proposed, where the compensation of the field induced by these regions can be made larger than that in a conventional voltage sustaining layer with the same breakdown voltage, and therefore the on-voltage can be reduced.
Abstract: A voltage-sustaining structure with embedded oppositely doped islands is proposed. Due to the compensation of the field induced by these regions, the doping density of the voltage-sustaining layer can be made larger than that in a conventional voltage-sustaining layer with the same breakdown voltage, and therefore the on-voltage can be reduced. The theory of design for such structures is found to be in good agreement with the results of full 2-dimensional simulation. The on-state performance, the transient behaviour and the potential applications of this structure in power devices are also discussed.

9 citations



Journal ArticleDOI
TL;DR: In this paper, a multipole theory (MT) method is presented for calculating two-dimensional (2D) Laplace equation boundary-value problem, by the mathematical deduction, the generalized MT series formula and its applied laws are derived.
Abstract: A new approach, the multipole theory (MT) method, is presented for calculating two-dimensional (2-D) Laplace equation boundary-value problem. By the mathematical deduction, the generalized MT series formula and its applied laws are derived. The numerical analysis procedure and application of the MT method in electromagnetic engineering have been discussed. In order to verify the accuracy of this method, the MT method is applied to calculate the characteristic impedances of transmission lines of various cross-section configurations. The results obtained by the MT method are compared with exact data reported in the literature. It has been proven that the MT method is an effective approach for calculating 2-D Laplace equation boundary-value problems.

Journal ArticleDOI
TL;DR: In this paper, a two and one half dimensional particle-in-cell code MAGIC has been used to investigate the nonlinear beam-wave interaction in a coaxial relativistic backward wave oscillator (RBWO) and optimize the dependence of the output power on electron beam nature parameter, slow wave structure geometry and magnetic guide field.
Abstract: A two and one half dimensional particle-in-cell code MAGIC has been used to investigate the nonlinear beam-wave interaction in a coaxial relativistic backward wave oscillator(RBWO) and optimize the dependence of the output power on electron beam nature parameter, slow wave structure geometry and magnetic guide field. The optimum conditions for the coaxial RBWO were obtained. The simulation results show: the coaxial RBWO can generate 3.2GW peak output power at 10.2GHz in the TM02 made when an annular electron beam of 20KA is accelerated across a diode potential of 600KV and guided through a section of uniform coaxial corrugated waveguide by an axial magnetic field of 25KG, the peak efficiency is about 27% . A novel coaxial master oscillator–power amplifier was presented in this paper.

Journal ArticleDOI
Abstract: The plasma filled dielectric Cerenkov maser considering the effect of the plasma grating has been studied. The plasma grating is formed by the modulation of the strong fields. According to the plasma-grating model, An equivalent model is constructed. The modified dispersion relation has been derived .The numerical results show that when the modulation over the background plasma increases, the operation frequency also increases, however, the growth rate varies slightly. Compared with the calculation results obtained by treating the plasma as uniform fluids, the calculation results with the equivalent model describe the bounded bandwidth of the dielectric oscillator more precisely.

Journal ArticleDOI
TL;DR: Bend as one type of the stripline discontinuities will be modeled in this paper as a multilayer perceptron neural network (MLPNN) is used to model the bend discontinUities in striplines.
Abstract: Stripline discontinuities are basic elements of many stripline circuits, such as the multilayer microwave monolithic ICs and the interconnect systems in high-speed digital circuits. Bend as one type of the stripline discontinuities will be modeled in this paper. A multilayer perceptron neural network(MLPNN) is used to model the bend discontinuities in stripline circuits. The MLPNN is electromagnetically developed with a set of training data that are produced by the full-wave finite-difference time-domain (FDTD) method. The full-factor design of experiments is used to determine the size of the training data.

Journal ArticleDOI
TL;DR: In this paper, a new family of pentagonal waveguides is proposed for high-power microwave transmission Conformal Mapping combined Finite Difference Method (CMFD) is used to analyze the propagation characteristic of the waveguide.
Abstract: In this paper a new family of pentagonal waveguides is proposed for high-power microwave transmission Conformal Mapping combined Finite Difference Method (CMFD) is used to analyze the propagation characteristic of the waveguide. A novel means of experiment for measuring cutoff frequencies of the waveguides with arbitrary cross section is also proposed and applied successfully.

Journal ArticleDOI
TL;DR: In this paper, the dispersion equation of electromagnetic wave was derived for corrugated waveguide filled with plasma immersed in magnetic field under assumption of small corrugation, and the density spectrum of plasma mode was demonstrated.
Abstract: The dispersion equation of electromagnetic wave is derived for corrugated waveguide filled with plasma immersed in magnetic field under assumption of small corrugation, the dispersion characteristics of low frequency plasma mode are calculated and analyzed, the dense spectrum of plasma mode is demonstrated.

Journal ArticleDOI
TL;DR: A multilayer perceptron neural network (MLPNN) is used to model the double-vias in multilayers stripline circuits using the full-wave finite-difference time-domain method.
Abstract: Multi-vias is a kind of interconnection largely existing in the multi-chip module (MCM) packages for high-speed digital circuits. In this paper, a multilayer perceptron neural network (MLPNN) is used to model the double-vias in multilayer stripline circuits. The MLPNN is electromagnetically developed with a set of training data that are produced by the full-wave finite-difference time-domain (FDTD) method. One type of the designs of experiments, the central composite technique, is used to allow for a minimum number of FDTD simulations that is needed to be performed.

Journal ArticleDOI
TL;DR: In this article, an ANN model for the frequency dependence of a radar cross section (RCS) is proposed and trained by means of the measured data, which can be extended to a lower or higher frequency region.
Abstract: During recent years, the artificial neural network (ANN) has been applied to electromagnetic (EM) engineering as a fast and flexible method for modeling, simulation, and optimization. In this paper, an ANN model for the frequency dependence of a radar cross section (RCS) is proposed and trained by means of the measured data. Using this trained ANN model, the frequency dependence of an RCS can be extended to a lower or higher frequency region. The extended results are in reasonably good agreement with the measured and computed results by the optical model published. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 315–318, 1999.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the corrections for matrix absorption, multiple overlapping interference and background in XRF can be combined in a limited range of wavelengths, using the theories of the scattering internal standard technique and the linear relationship between backgrounds.
Abstract: It is shown that the corrections for matrix absorption, multiple overlapping interference and background in XRF can be combined in a limited range of wavelengths. Two comprehensive correction equations were derived from the theories of the scattering internal standard technique and the linear relationship between backgrounds. The determination of the trace element molybdenum in geological samples is reported as an example of the application of the combination correction technique.

Journal ArticleDOI
TL;DR: A multilayer perceptron neural network (MLPNN) is used to model the electrical properties of the crossover discontinuities in stripline circuits using the full-wave finite-difference time-domain method.
Abstract: Crossover discontinuities between two adjacent orthogonal signal layers often appear in many stripline circuits, such as the multilayer microwave monolithic ICs and the interconnect systems in high-speed digital circuits. In this paper , a multilayer perceptron neural network(MLPNN) is used to model the electrical properties of the crossover discontinuities in stripline circuits. The MLPNN is electromagnetically developed with a set of training data that are produced by the full-wave finite-difference time-domain method. The full-factor design of experiments is used to determine the size of the training data.

Journal ArticleDOI
TL;DR: A multilayer perceptron neural network (MLPNN) is used to model a millimeter wave coaxial to waveguide adapter using the full-wave finite-difference time-domain (FDTD) method.
Abstract: Artificial neural networks provide fast and accurate models for the modeling, simulation, and optimization of microwave and millimeter wave components. In this paper, a multilayer perceptron neural network (MLPNN) is used to model a millimeter wave coaxial to waveguide adapter. The MLPNN is electromagnetically developed with a set of training data that are produced by the full-wave finite-difference time-domain (FDTD) method. One type of the designs of experiments, the central composite technique, is used to allow for a minimum number of FDTD simulations that is needed to be performed. The MLPNN models are useful for the CAD of wideband coaxial to waveguide adapter.

Journal ArticleDOI
TL;DR: In this article, the self-consistent nonlinear theory is employed to analyze the inner-slotted high harmonic gyrotron, it is found that the structure of advantiageus to the interactin, the efficiency of interaction is above 30%.
Abstract: The self-consistent nonlinear theory is employed to analyze the inner-slotted high harmonic gyrotron, it is found that the structure of advantiageus to the interactin, the efficiency of interaction is above 30%.

Journal ArticleDOI
TL;DR: In this paper, a step-loaded groove waveguide is presented and analyzed by means of a field-matching method, and the dispersion equation of this structure is derived by using a field matching method.
Abstract: A new kind of helical groove structure, step-loaded groove waveguide is presented and analyzed in this paper. The dispersion equation of this structure is derived by means of a field-matching method. This equation may be reduced to the dispersion equation of helical ridge-loaded structure and rectangular one. In order to demonstrate the influence of the step on the dispersion properties, the comparison of the dispersion characteristics is made in these helical rectangular and modified rectangular groove structures. Form the analysis, it is shown that the step loading tends to reduce the dispersion of the helical groove circuit and the step-loaded structure has the weaker dispersion compared with the rectangular one or the ridge-loaded one. The effect of the step shape on the wave properties is also discussed under the deep groove case. The theoretical results explicitly indicate that the V-like step-loaded structure has the weakest dispersion in all step-loaded structures.

Journal ArticleDOI
TL;DR: In this paper, a 3-in. YAG projection CRT for an HDTV display was developed, which achieved luminances of 1.4 × 105, 6.2 × 104, and 8 × 103 cd/m2 at a cathode current of 0.0 mA and an anode voltage of 29 kV with a half-intensity linewidth of 85 μm.
Abstract: — We have developed a 3-in. YAG (yttrium aluminum garnet) projection CRT for an HDTV display. The densely packed phosphor screen with a multi-layer interference filter is prepared by depositing phosphor on a YAG faceplate using a centrifugal sedimentation method. The tube's envelope is made from a glass whose expansion coefficient is well-matched with that of YAG. The focusing characteristics of an optimally designed pre-focusing electron gun and focusing magnet are improved for a HDTV display application. As a result, the green, red, and blue tubes reached luminances of 1.4 × 105, 6.2 × 104, and 8 × 103 cd/m2 at a cathode current of 1.0 mA and an anode voltage of 29 kV, respectively, with a half-intensity linewidth of 85 μm. An experimental 48-in. rear-projection TV set using the YAG projection tubes achieves more than 1000-TV-lines horizontal resolution and 300-cd/m2 mean white luminance.

Journal ArticleDOI
TL;DR: A new digital modulation recognition method that can significantly improve the recognition performance in lower SNR with better robustness is proposed in this paper.
Abstract: Based on the features extracted from generalized autoregressive (GAR) model parameters of the received waveform, and the use of multilayer perceptron(MLP) neural network classifier, a new digital modulation recognition method is proposed in this paper. Because of the better noise suppression ability of the GAR model and the powerful pattern classification capacity of the MLP neural network classifier, the new method can significantly improve the recognition performance in lower SNR with better robustness. To assess the performance of the new method, computer simulations are also performed.

Journal ArticleDOI
01 Dec 1999-Vacuum
TL;DR: In this article, a new thin film transformer which is composed of an E-shaped CoZrRe magnetic layer and wound with Cu thin film coils fabricated by using a mask vacuum evaporation process has been investigated.

Proceedings ArticleDOI
01 Jan 1999
TL;DR: In this paper, an heuristic algorithm is proposed for the dynamic centralized wavelength assignment problem in fixed-routing WDM networks without wavelength conversion, which performs better than other previously proposed algorithms in most of the cases studied.
Abstract: An heuristic algorithm is proposed for the dynamic centralized wavelength assignment problem in fixed-routing WDM networks without wavelength conversion. Simulation results show that it performs better than other previously proposed algorithms in most of the cases studied.

Journal ArticleDOI
TL;DR: Cell averaging and other statistic CFAR detection of gamma distributed targets against K-distributed clutter in multi-look SAR images are studied and formulated and results in terms of detectability losses due to 'spikiness' of the clutter are discussed.
Abstract: Cell averaging and other statistic CFAR detection of gamma distributed targets against K-distributed clutter in multi-look SAR images are studied and formulated. Two numerical methods for evaluating the performances of the CFAR detectors are described. Numerical results in terms of detectability losses due to 'spikiness' of the clutter are plotted and discussed.

Journal ArticleDOI
TL;DR: In this article, the behavior of a two-stage slotted Gyro-TWT amplifier is evaluated with a self-consistent nonlinear slow-timescale simulation code, where the effects of the sever position and the lengths of the first section, sever, and the second section on beam-wave interaction are discussed.
Abstract: The behavior of a two-stage slotted Gyro-TWT amplifier is evaluated with a self-consistent nonlinear slow-timescale simulation code. The effects of the sever position and the lengths of the first section, sever, and the second section on beam-wave interaction are discussed in this paper. And the influences of the magnetic field and the electron beam's velocity spread on efficiency, gain and bandwidth are also simulated and discussed in detail. The electron beam we employ encircles around the axis of the wave guide.

Proceedings ArticleDOI
01 Nov 1999
TL;DR: In this paper, the wave splitting method is used to analyze a plane wave incident into an infinite inhomogeneous lossless chiral medium, where the permeability, the permittivity and the chiral admittance varies with the depth.
Abstract: This paper introduces the wave-splitting method and it is important that the Green's functions derived by this method are independent of the incident and scattered fields and depend only on the properties of the medium, so we use the functions to analyze a plane wave incident into an infinite inhomogeneous lossless chiral medium, where the permeability, the permittivity and the chiral admittance varies with the depth.