Showing papers in "Journal of Electronics (china) in 1989"
TL;DR: In order to handle the problem that the contrast decreases in the dark region caused by underexposure, this detector uses a self-adjusting threshold, so that it can detect the edge in regions of different grey background correctly.
Abstract: This paper presents a new edge detector using 5×5 mask, which can reduce noise efficiently but not increase the width of the detected edge which always happens in the case of using the 5×5 window edge detector. Besides, in order to handle the problem that the contrast decreases in the dark region caused by underexposure, this detector uses a self-adjusting threshold, so that it can detect the edge in regions of different grey background correctly
8 citations
TL;DR: In this article, the eigenvalue problem of a multilayer dielectric waveguide consisting of arbitrary number of layers is solved by the microwave network method, and a general program with the function of computer graphics has been developed for analyzing the dispersion characteristics and the electromagnetic field distributions of an N layer dielectoric waveguide.
Abstract: In this paper, the eigenvalue problem of a multilayer dielectric waveguide consisting of arbitrary number of layers is solved by the microwave network method. A general program with the function of computer graphics has been developed for analyzing the dispersion characteristics and the electromagnetic field distributions of anN layer dielectric waveguide. As an example of practical applications, the procedure of mode conversion and mode separation in dielectric branching wavegu i des is vividly demonstrated through analyzing the field distributions of asymmetric multilayer dielectric structures and the general rules of mode conversion are discussed.
2 citations
TL;DR: Zhang et al. as mentioned in this paper introduced a specific image processing software for GaAs material, called ZHIMAG (ZHang IMAGe) and its application to GaAs wafer.
Abstract: A new method is applied to characterize the defects in GaAs material (e. g. the absorption of EL2 centres). The method consists of transmitting a laser beam (λ=1.1–1.5 μm) through the GaAs wafer of 4–8 mm thickness and 50 mm diameter. The image is received by the TOSHIBA 8844, camera and entered into the DATASUD computer image processing system. This image is displayed on a monitor permitting to observe the inhomogeneity (like cross, cells and volutes) of the EL2 and dislocation defects. This paper will introduce a specific image processing software for GaAs material, called ZHIMAG (ZHang IMAGe) and its application to GaAs wafer. The software can be also applied to any other types of image processing.
1 citations
TL;DR: In this article, the capacitances of rectangular shielded lines with offset inner conductors were calculated using the partial charge simulation method, which can improve the accuracy by increasing the term number of series.
Abstract: The partial charge—simulation method is presented for calculating the capacitances of rectangular shielded lines with offset inner conductors. The capacitances calculated by using this method are in good agreement with those of other available methods. This method can improve the accuracy by increasing the term numberN of series.
1 citations
TL;DR: In this article, the boundary element method is used to find the cut-off frequencies of two-dielectric layered waveguides. But the method is of an appreciable precision.
Abstract: This paper diseusses the general principle of finding the cut-off frequencies in two-dielectric layered waveguides by using the boundary element method, based on the fundamental solution of a two dimensional Helmholtz equation. In terms of the formulae given in the paper, some numerical results are obtained for two commonly used configurations. The fimal results show that the method is of an appreciable precision.
1 citations
TL;DR: In this article, the effects of a beam thickness and a conducting wall in a free electron laser with a linearly polarized wiggler magnetic field and an axial magnetic field are investigated within the framework of fluid-Maxwell equations.
Abstract: The effects of a beam thickness and a conducting wall in a free electron laser with a linearly polarized wiggler magnetic field and an axial magnetic field are investigated within the framework of fluid-Maxwell equations. The growth rate of free electron laser instability is obtained, in which the nonlinear bulk and surface current density are simultaneously considered. The numerical calculations indicate that the bulk coupling is dominant. There is an optimum beam thickness and separation between the conducting walls for which the growth rate is maximum.
1 citations
TL;DR: In this article, a broadband two-port feeding technique based on the principle of reactance compensation is suggested. But it is not shown that this technique enables the VSWR bandwidth to be broadened to 2-3 or more times that of a conventional design for both linear and circular polarization operation.
Abstract: In order to broaden the bandwidth of a microstrip patch antenna, a broadband two-port feeding technique based on the principle of reactance compensation is suggested. The principle and some design guidelines are presented; the calculating model of a practical configuration as well as its parameter optimization is demonstrated, followed by several kinds of test models with their experimental results. It is shown that this technique enables the VSWR bandwidth to be broadened to 2–3 or more times that of a conventional design for both linear and circular polarization operation.
1 citations
TL;DR: In this paper, the authors used canonical piecewise linear analysis method to analyze nonlinear DC fault circuits and solve for the values of the test port voltages which are selected beforehand.
Abstract: This paper uses canonical piecewise—linear analysis method to analyze nonlinear DC fault circuits and solve for the values of the test port voltages which are selected beforehand. The method needs less memory storages, obtains the results in finite steps and has high efficiency in computation. It can be applied to the circuits containing multiport nonlinear elements. It is a good method of pre—test analysis for fault circuits in simulation—before—test aproach in analogue circuit diagnosis.
1 citations
TL;DR: In this paper, a theoretical formula for measuring the power-law spectrum with interferometer is presented for the study of ionosphere, and the results of theoretical calculation agree well with the measurements.
Abstract: A theoretical formula for measuring the power—law spectrum with interferometer is presented in this paper for the study of ionosphere. The results of theoretical calculation agree well with the measurements. The radio scintillation power—law spectrum index which is caused by the irregularities in the ionosphere is determined to bep=3.5 from the results.
TL;DR: In this paper, the normal and abnormal cylindrical vector wave functions are constructed and some important conversion relations in circular, elliptic, and parabolic CVC coordinate systems are discussed in detail.
Abstract: The normal and abnormal cylindrical vector wave functions are constructed. Some important conversion relations in circular, elliptic and parabolic cylindrical coordinate systems are discussed in detail, where the result in circular cylindrical coordinate system is the same as the one given by the author (1984).
TL;DR: The authors have proved that, in the case of radix 2, the RCFA is exactly equivalent to the twiddle factor merged frequency-decimal FFT algorithm, and can be replaced by the more efficient algorithm—the twiddleFactor merged FFT algorithms, with exactly the same external property and the similar internal structure.
Abstract: Martens proposed a highly efficient and simply formed DFT algorithm—RCFA whose efficiency is comparable with that of WFTA or that of PFA, and whose structure is similar to that of FFT. The authors have proved that, in the case of radix 2, the RCFA is exactly equivalent to the twiddle factor merged frequency-decimal FFT algorithm. The twiddle factor merged time-decimal FFT algorithm is provided in this paper. Thus, in any case, the FFT algorithm used currently can be replaced by the more efficient algorithm—the twiddle factor merged FFT algorithm, with exactly the same external property and the similar internal structure. Also in this paper, the software for implementing the twiddle factor merged FFT algorithm (TMFFT) is provided.
TL;DR: With this method a computer program in FORTRAN language is realized on the computers FELIX C-512 and IBM-PC, and good results are obtained in practical operations.
Abstract: Some new concepts of effective incidence matrix, ascending order adjacency matrix and end-result vertex are introduced, and some improvements of the maximum weight matching algorithm are made. With this method a computer program in FORTRAN language is realized on the computers FELIX C-512 and IBM-PC. Good results are obtained in practical operations.
TL;DR: In this article, the properties of coherent radiation of millimeter waves generated by an intense rotating annular relativistic electron beam (E-layer) which is from a cusp magnetic field are investigated.
Abstract: Properties of coherent radiation of millimeter waves generated by an intense rotating annular relativistic electron beam (E-layer) which is from a cusp magnetic field are investigated. The linearized Vlasov- Maxwell equations are used to analyze the interaction between E- layer and resonators of the magnetron. The dispersion relation is deduced and numerical calculation is made. The results show that the frequency of microwave radiation isωτ (ωω=lΩ‖ where Ω‖ is the electron relativistic cyclotron frequency in the axial magnetic field;l is the azimuthal mode number,l=n+mN;N is the number of side resonators,n=0,1,2,…N/2,m is any integer). The growth rate of radiation is still large enough even ifl is large. It is good for generating a millimeter wave radiation at low axial magnetic field. If the modes can be controlled well, a tunable, high power millimeter wave device can be made.
TL;DR: In this article, the optimal magnetizing fields of the variable polarization effects of ferrite are studied by using the coupling-wave(cw) theory, vaiational principle and optimization techniques.
Abstract: The optimal magnetizing fields of the variable polarization effects of ferrite are studied by using the coupling-wave(cw) theory, vaiational principle and optimization techniques. Several kinds of shapes of the magnetic line of force and some valuable results of the optimal magnetizing field are given. The theoretical calculations are in good agreement with the experimental results.
TL;DR: In this paper, a new approach to the EM scattering problem of an inhomogeneous lossy dielectric body is proposed, where the entire interior electric field distribution can be obtained from the measured exterior field distribution by simple recurrence relations.
Abstract: A new approach to the EM scattering problem of an inhomogeneous lossy dielectric body is proposed. It is shown that the entire interior electric field distribution can be obtained from the measured exterior field distribution by simple recurrence relations. Detailed derivations of these recurrence relations for the field distribution inside the scattering body are presented, and the results obtained by computer simulations are given.
TL;DR: In this paper, a new kind of Ba-W dispenser cathode impregnated with barium ytterbate has been developed, which has good properties; high coefficient of secondary emission, strong ability of resisting oxygen poisoning, high thermionic emission current density and more uniform emission on the cathode surface.
Abstract: A new kind of Ba- W dispenser cathode impregnated with barium ytterbate has been developed. It has good properties; high coefficient of secondary emission, strong ability of resisting oxygen poisoning, high thermionic emission current density and more uniform emission on the cathode surface. The cathode is suitable for using as an electron emitter for microwave tubes, especially magnetrons.
TL;DR: In this paper, the scattering and propagation integral equations for solving the problems of discontinuous dielectric structure are obtained from the mode-matching method, by doing some transforms and derivations, the necessary and sufficient condition for the existence of solution of propagating equations is given.
Abstract: From the mode-matching method, by doing some transforms and derivations, the scattering and propagation integral equations for solving the problems of discontinuous dielectric structure are obtained. The necessary and sufficient condition for the existence of solution of propagating equations is given. It is really the dispersion equation of the dielectric structure. As an example, a succinct solution of one-step discontinuous dielectric structure is derived.
TL;DR: In this paper, an approximate formula of space charge field of orotron in rectangular coordinate system is derived, when one of the boundaries is infinite, and the effect of this charge on the performance of the device is discussed.
Abstract: An approximate formula of space charge field of orotron in rectangular coordinate system. when one of the boundaries is infinite, is derived. Using this model the self-consistant large signal interaction of orotron with space charge is calculated, and the effect of this charge on the performance of the device is discussed.
TL;DR: In this article, a new modeling and filtering approach for tracking maneuvering targets is presented, which makes optimal estimate for the model with the random variable possible, depends on random step modeling of target maneuvers.
Abstract: A new modeling and filtering approach for tracking maneuvering targets is presented in this paper. The approach, which makes optimal estimate for the model with the random variable possible, depends on random step modeling of target maneuvers. In the new model, the unknown target acceleration is treated as a random variable and then estimated directly. A detector is designed to find out the target maneuvers and the estimation algorithm will be restarted when the maneuvers occur. Combination of three—dimention Kalman filter with a detector, forms a tracker for maneuvering targets. The new tracking scheme is easy to implement and its capability is illustrated in two tracking examples in which the new approach is compared with Mooses' on the performance.
TL;DR: In this paper, a new method for measuring ocean wave length and direction from SEASAT Synthetic Aperture Radar (SAR) remote sensing image is presented, where an ocean wave image is sampled in certain directions, the samples are then analyzed by using one dimensional Fourier Transformation to calculate the ocean wave correlation function.
Abstract: A new method for measuring ocean wave length and direction from SEASAT Synthetic Aperture Radar (SAR) remote sensing image is presented in the paper. In the new method, an ocean wave image is sampled in certain directions, the samples are then analyzed by using one dimensional Fourier Transformation to calculate the ocean wave correlation function. Finally the ocean wave length and direction are determined from the ocean wave correlation function. The new method is better than the traditional two-dimensional Fourier Transformation method in both consuming time and precision.
TL;DR: A novel method that adopts the Voltage Control Voltage Source (VCVS)equalized transformation to revise the original LC ladder filter and induce it into 16 basic sections and the extend the principle of the LT in order to fit active and 3 port networks and give out switched-capacitor circuits corresponding to the 16basic sections.
Abstract: This paper presents a novel method that is applied to realize the Linear Transformation (LT) Switched-Capacitor Filter (SCF). It adopts the Voltage Control Voltage Source (VCVS)equalized transformation to revise the original LC ladder filter and induce it into 16 basic sections and the extend the principle of the LT in order to fit active and 3 port networks and give out switched-capacitor circuits corresponding to the 16 basic sections, which can realize all four kinds of filters—LP, HP, BP, BS filters. Designed examples are given here. An Nth order filter only requires N amplifiers and the circuit is insensitive to parasitic capacitances. The experimental results of a 3rd order elliptic LP and a 6th order elliptic BP are given and agree with the theory.
TL;DR: In this article, the spontaneous radiation from a single pulse electron beam in Free Electron Lasers is dealt with by solving one-dimensional wave equations, and the obtained results show that there is the long pulse effect as well as the well-known short pulse effect.
Abstract: The spontaneous radiation from a single pulse electron beam in Free Electron Lasers is dealt with by solving one-dimensional wave equations. The obtained results show that there is the long pulse effect as well as the well-known short pulse effect.
Abstract: On the basis of a work of Wu Jianqiang et al. (1987), by making use of the linear kinetic theory, the gyromonotron with a combining periodic magnetic field and a coaxial cyclotron electron beam has been analysed in detail. And the formulas of the electron beam to wave interaction power, frequency shift and starting current, etc. have been derived.
TL;DR: In this paper, a new general biquadratic SC structure in which the GB effect is reduced is developed, and the structure is stray-insensitive, and has very lowWo andQ sensitivities.
Abstract: In this paper, the problem how to reduce the GB effect in SC filters is discussed. A new general biquadratic SC structure in which the GB effect is reduced is developed. The structure is stray-insensitive, and has very lowWo andQ sensitivities. Using the low-pass SC filter for an example, method of reducing the GB effect has been shown in detail.
TL;DR: In this article, a microcomputerized measurement system was developed to automatically acquire an I-V characteristic curve in 5 seconds with the accuracy of 0.05% FSR (full scale range).
Abstract: A microcomputerized measurement system is developed. This system automatically acquires anI–V characteristic curve in 5 seconds with the accuracy of 0.05% FSR (full scale range). The Schottky extrapolation field-free emission, the inflection point emission, the flection-point emission, the average effective work function, the Richardson work function, the work function distribution at the operation temperature and other important information that reflects properties of cathodes are obtained by this system. The results of analysing four types of cathodes demonstrate that this system is very suitable for measuring the activity changes of the cathode in the processes of activation, ageing, poisoning and life test. It is proved that this system can also be used to monitor the activity of the cathode in the assembled tube by measuring a grid controlled travelling-wave tube.
TL;DR: In this article, a new processing technology and the properties of multialkali antimonide photocathodes are described, which requires an initial antimony layer to be deposited on a fiber-optic window at a suitable temperature.
Abstract: A new processing technology and the properties of multialkali antimonide photocathodes are described. The technique requires an initial antimony layer to be deposited on a fiber-optic window at a suitable temperature. After that, the layer is activated by multialkali and antimonide. Thus, the multialkali photocathodes named “The Modern Multialkali Photocathode” are obtained. It has been found that a photocathode thus processed gives a sensitivity of 200 to 300μA/lm for white light at a color temperature of 2854K. This paper shows the variation of photosensitivity during processing of a Modern Multialkali Photocathode and the variation of spectral sensitivity at different wavelengths. The author discusses the results, gives a supposition of “photoemission center”, and discusses the role of Cs in multialkali photocathodes.
TL;DR: In this article, the scattering properties of the E-plane uniform dielectric posts in rectangular waveguide are numerically analyzed by the moment method, and the higher order modes are considered in calculation, improving the computation accuracy and providing the scattering information of all modes excited as well.
Abstract: Based on the polarization current integral equation with the modified Green's Function as kernel, the scattering properties of the E-plane uniform dielectric posts in rectangular waveguide are numerically analyzed by the moment method. These posts are of arbitrary cross section and post-number. The calculation accuracy and speed are remarkable improved by segmenting the dielectric region into many small rectangular oells and applying local analytic integration. The higher-order modes are considered in calculation, improving the computation accuracy and providing the scattering information of all modes excited as well.
TL;DR: In this article, the principle of an optical method of photocathode processing control, which is one of the most widely used methods for processing photocathodes, has been discussed and a designed monitoring apparatus is described and applied to investigate the optical parameters of multialkali photoemitter during the process of fabrication.
Abstract: The principle of an optical method of photocathode processing control, which is one of photocathode processing monitoring techniques, is discussed. A designed monitoring apparatus is described and has been applied to investigate the optical parameters of multialkali photoemitter during the process of fabrication. Some actual schemes using the method to monitor the preparation of photocathodes are suggested.
TL;DR: In this article, the dispersion characteristics of a class of closed dielectric waveguides are investigated by the method which combines the building-block approach of multimode network theory with the rigorous mode matching procedure.
Abstract: The dispersion characteristics of a class of closed dielectric waveguides are investigated by the method which combines the building-block approach of multimode network theory with the rigorous mode matching procedure. Several numerical examples for different guiding structures have been given by the approach. The same structures are also analyzed with the finite element method and the EDC method for comparison. The calculations show that the present approach yields as highly accurate results as the finite element method while almost retaining the simplicity of the EDC method, and justify the utility of the present method.
TL;DR: The computation shows that the mathematical algorithm and the corresponding programs developed in this paper are relatively simple and accurate enough for the engineering design of single-mode fibers for optical communication systems.
Abstract: This paper describes a method for fast engineering evaluation of the transmission characteristics of single-mode optical fibers. A versatile microcomputer program is presented which can be utilized to analyze mode field characteristics of single-mode fibers with arbitrary refractive index profiles. Our computation shows that the mathematical algorithm and the corresponding programs developed in this paper are relatively simple and accurate enough for the engineering design of single-mode fibers for optical communication systems.