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1992 Vol. 14, No. 4

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Articles
IMPROVEMENT OF THE ALGORITHM PRINCIPLE FOR MINIMIZATION OF MULTI-OUTPUT FUNCTIONS
Chen Su, Xu Daorong
1992, 14(4): 337-343.
Abstract:
The application of extraction principle for logic function minimization to multiple-output cases is studied. The defect in original algorithm in dealing with multi-output extremals is complemented, and three kinds of less-than terms in different conditions are defined. In addition, three kinds of generations for the definition of less-than terms are given, so as to more efficiently find out the coverage with minimal number of terms and irredundant function outputs. Finally, an algorithm MOSE based on the work is presented.
ANALYSIS OF MULTI-TONE INTERFERENCE SUPPRESSION IN HF SERIAL DATA TRANSMISSION SYSTEMS
Tang Jun, Li Zhengang, Li Leming
1992, 14(4): 344-353.
Abstract:
The multi-tone interferences suppression in HF serial data transmission systems is analysed. Analytic expressions for the tap weights and minimum mean square errors of adaptive equalizer in HF serial systems are obtained. The rate of convergence of equalizer in the presence of multi-tone interferences is analysed. The analytic and simulated results indicate that the equalizer in HF serial systems can not only track the rapid variation of HF channel but also suppress the multi-tone interferences perfectly.
A NEW ADAPTIVE EQUALIZER STRUCTURE FOR NONLINEAR CHANNELS
Wang Yongde
1992, 14(4): 354-360.
Abstract:
Based on analysis of non-linear channel models, a new connectionist model adaptive equalizer is constructed. Comparing with the connectionist model using the Volterra series to extend the input vector space, the number of weights with new structure is reduced significantly. It is shown by simulations that the weight values of the new scheme converge to the optimal values closely for nonminimum phase channels as well as minimum phase channels, if the channel noise is small enough, Testing results of the BER (Bit Error Rate) show that the new adaptive equalizer for non-linear channels is superior to the linear equalizer in the equalization performances.
ANALYSIS OF CLASS E TUNED POWER AMPLIFIER WITH ANTIPARALLEL DIODE AT SWITCH
Qu Ming, Xie Aiguo
1992, 14(4): 361-370.
Abstract:
A general approach to analysis of class E tuned power amplifier with anti-parallel diode at switch is presented. First, the determination of diode active angle is discussed. Then the amplifier output response, along with performance evaluation, is derived and expressed in the closed form Fourier series by combining Fourier analysis and state equation technique. Applications to several amplifiers with varying param eters show that the method is fast and robust. The proposed approach affords an effective means to the exact analysis and design of class E tuned power amplifier with parallel diode at switch.
RECONSTRUCTION OF ONE-DEMENSIONAL MULTIPLE-LAYERED MEDIUM USING A TIME-DOMAIN S1GNAL-FLOWGRAPH TECHNIQUE
Cui Tiejun, Liang Changhong
1992, 14(4): 371-378.
Abstract:
A new method to reconstruct multiple-layered medium is first proposedby using a time-domain signal-flow graph (TDSFG) technique. With the equivalent network of the medium, a concept of TDSFG is given, and its rules are derived. Furthermore, the reflection principles in time domain are analysed, and a reconstruction method is establshed.
L CALIBRATION FOR DUAL-SIX-PORT NETWORK ANALYZER AND ANALYSIS OF SYSTEM MEASURING ERROR
Shen Dongya, Ruan Chengli, Lin Weigan
1992, 14(4): 379-384.
Abstract:
A new method-L calibration technique for calibrating the duali-six-port network analyzer is proposed. Usinf this method a section of transmission line is needed only, and its length is not necessary to be known accurately. The measuring errors introduced by non-ideal isolators are discussed, and the degree of isolation needed for the system working in the quasi-ideal condition is given.
THEORY OF CIRCULAR FREE ELECTRON LASER WITH AN INTENSE RELATIVISTIC NONNEUTRAL ELECTRON RING
Yin Yuanzhao
1992, 14(4): 385-389.
Abstract:
The working properties of a circular free electron laser with an intenserelarivistic nonneutral electron ring have been investigated with in the framework of the Vla-sov-Maxwell equations. The results show that the space charge of intense electron beam can enhance the radiation growth rate and frequency
THE RELATIONSHIP BETWEEN THE EM ENERGY ABSORPTION OF HUMAN BODY AND THE INCIDENT DIRECTION AND POLARIZATION OF PLANE WAVE
Wang Changqing, Zhu Xili
1992, 14(4): 390-395.
Abstract:
The problems of EM energy absorption of human body irradiated by plane wave are discussed by using the Finite-Difference Time-Domain (FD-TD) method. The local SAR (Specific Absorption Rare), the whole-body-averaged SAR and the layer-averaged SAR for the inhomogenous block model of human body with different incident direction and different polarization of the incident waves are calculated. The results show that the appearance of maximum EM energy absorption is not always at the situation of the front inciden...
HIGH-ORDER FINITE-ELEMENT ANALYSIS OF VARIOUS COAXIAL LINES WITH ARBITRARY CROSS-SECTIONS
Xu Shanjia, Sheng Xinqing
1992, 14(4): 396-403.
Abstract:
The high-order finite-element method is used for analyzing the characteristic impedances of the coaxial lines with arbitrary cross-sectons. A standard program with second order element analysis for calculating the characteristic impedances of various coaxial lines is developed. A computer automatic division technique is proposed to faciliate the development of the general program. As a result, the whole analysis procedure becomes simple and the solusion efficency raises tremendously. The calculations of the...
ON THE PHASE CENTER OF ELECTROMAGNETIC HORNS
Yi Yihong, Li Sifan
1992, 14(4): 404-408.
Abstract:
The characteristics of the phase centers of electromagnetic horns holdingnearly symmetric pattern are presented analytically. It is proved that the phase center on the = 45 plane coincides with the average phase center, and if a single plane phase center is used to define the horn phase center approximate y, the = 45 plane phase center will be the best choice.
ON OSCILLATIONS IN HIGH POWER KLYSTRONS
Ding Yaogen
1992, 14(4): 409-415.
Abstract:
Two different types of oscillations observed in S-band 20 MW high power klystron and S-band 1.5 MW broadband klystron are described in detail. Experiments and theoretical analysis show that one type of oscillation is diode oscillation happened in the ele-ctron gun region, and the other is -mode monotron oscillation caused by the first high order mode TM011 of the klystron cavities. In order to suppress the diode oscillation, the geometry of the electron gun has been redesigned for destroying the phase condition of the oscillation. In order to overcome the -mode monotron oscillation, the QL of cavities is decreased t0 300- 400 by plasma coating the microwave attenuation material on the interior surface of cavjties. The research work on these types of oscillations provides valuable theoretical and experimental design basis for high peak and high average power klystrons with good performance, high stability and reliability.
ON STABILITY STUDY OF NEURAL NETWORKS WITH RANDOM PERTURBATION
Liao Guisheng, Jiao Lichen, Bao Zheng
1992, 14(4): 416-419.
Abstract:
Based on the theory of stochestic differential equation, the stability of a kind of generalized continuous-time Hopfield neural network with white noise perturbation is studied, and the related stability criteria and design requirements of neural networks are established.
AN IMPROVEMENT OF THE RECURSIVE CLOSED-FORM ALGORITHM FOR NON-MINIMUM PHASE FIR SYSTEM IDENTIFICATION
Liang Yingchang, Wang Shuxun, Dai Yisong
1992, 14(4): 420-423.
Abstract:
An improved algorithm which is based on the recursive closed-form algorithm for non-minimum phase FIR system identification via higher order statistics is presented. In order to increase the parameter estimation accuracy, the improved algorithm uses the optimal iterative method for nonlinear least-square solition. Finally the simulation examples are also given.
THRESHOLDING OF IMAGES USING AN EFFICIENT c-MEAN CLUSTERING ALGORITHM
Liu Jianzhuang, Tu Yuqing
1992, 14(4): 424-427.
Abstract:
Otsu s method (1979) is considered as a good thresholding method for image segmentation. In this paper, an efficient c-mean calustring algorithm which is suitable for image segmentation is proposed. It yields th came results as Otsu s method, but its computational time is about one order of magnitude less than that of Otsu s method.
A MODELLING SYSTEM FOR ELECTRONIC STRUCTURES OF MOLECULES
Wu Jing, Zhu Minhui, Ye Xueqi
1992, 14(4): 428-431.
Abstract:
A practical electronic structural modelling system is presented. This system can be used to study the distribution of intermolecular microscopic properties, such as electron densities and intermolecular potentials. It includes calculation and representation of molecular properties. Display of map is represented as isometric 3D mesh surface and fuzzy cloud dot map. This system has been used to study the anti-tumor drug, and some results are obtained.
AN ACCURATE FORMULA FOR CUTOFF VALUES OF TE WAVES ON NONLINEAR SLAB OPTICAL WAVEGUIDE
Chen Zhihao, Chen Xiyao, Lai Heng, Dai Yihuan
1992, 14(4): 432-435.
Abstract:
An accurate formula is derived for cutoff values of TE modes in the symmetric slab optical waveguide with a nonlinear thin film. Two examples are given. Computed results are in agreement with exact results in literatures.
WAVEGUIDE JUNCTION AND GUIDE-HORN RADIATOR ANALYSIS-GUIDED-WAVE NUMERICAL BOUNDARY CONDITIONS AND THEIR APPLICATIONS
Fan Desen, Wang Yuanxun
1992, 14(4): 436-440.
Abstract:
As an important aspect of partial differential equation solutions of open-region electromagnetic field problems, the concept and algorithm of guided-wave global numerical boundary conditions are presented. Emphasis is placed on the two-dimensional guided-wave scattering and radiation analysis in the waveguides with plate-conducting boundaries. This analysis method can be readily expanded to cover many other guided-wave systems, leading to a new theoretical approach to the guide-horn like radiator analysis.
ARRAYS OF UNEQUAL DIPOLES WITH SIMILAR INPUT IMPEDANCES
Chen Wei
1992, 14(4): 441-444.
Abstract:
The dependence of input impedance of a dipole element on the current distribution is studied, and a method for synthesizing a given radiation pattern from a new type of array of unequal dipoles is described. The input impedances of the elements are extremely similar to each other and the lengths of the dipoles are not equal.
THE DEVELOPMENT OF A NEW WAVEGUIDE PHASE SHIFTER
Pan Zongda
1992, 14(4): 445-448.
Abstract:
By the aid of the phase shift-frequency characteristic, the conformal transformation and the perturbation theory, a new kind of compact, broadband waveguide phase shifter is developed. It is used in the satellite earth station and achieves very nice performances. The experimental data coincide with the theoretical results.