1992 Vol.14 No.4, Published: 19 July 1992
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Chen Su; Xu Daorong
IMPROVEMENT OF THE ALGORITHM PRINCIPLE FOR MINIMIZATION OF MULTI-OUTPUT FUNCTIONS
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1992 Vol. 14 (4): 337-343
[Abstract]
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1849 )
[PDF 1210KB]
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810
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DOI:
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.
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Tang Jun①; Li Zhengang①;Li Leming②
ANALYSIS OF MULTI-TONE INTERFERENCE SUPPRESSION IN HF SERIAL DATA TRANSMISSION SYSTEMS
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1992 Vol. 14 (4): 344-353
[Abstract]
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1385 )
[PDF 1493KB]
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684
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DOI:
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.
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Wang Yongde
A NEW ADAPTIVE EQUALIZER STRUCTURE FOR NONLINEAR CHANNELS
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1992 Vol. 14 (4): 354-360
[Abstract]
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1448 )
[PDF 1289KB]
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770
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DOI:
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.
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Qu Ming①;Xie Aiguo②
ANALYSIS OF CLASS E TUNED POWER AMPLIFIER WITH ANTIPARALLEL DIODE AT SWITCH
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1992 Vol. 14 (4): 361-370
[Abstract]
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1912 )
[PDF 1489KB]
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586
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DOI:
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.
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Shen Dongya①;Ruan Chengli②; Lin Weigan②
"L" CALIBRATION FOR DUAL-SIX-PORT NETWORK ANALYZER AND ANALYSIS OF SYSTEM MEASURING ERROR
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1992 Vol. 14 (4): 379-384
[Abstract]
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1696 )
[PDF 1011KB]
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595
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DOI:
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.
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Wang Changqing; Zhu Xili
THE RELATIONSHIP BETWEEN THE EM ENERGY ABSORPTION OF HUMAN BODY AND THE INCIDENT DIRECTION AND POLARIZATION OF PLANE WAVE
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1992 Vol. 14 (4): 390-395
[Abstract]
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2393 )
[PDF 1146KB]
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1082
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DOI:
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...
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Xu Shanjia; Sheng Xinqing
HIGH-ORDER FINITE-ELEMENT ANALYSIS OF VARIOUS COAXIAL LINES WITH ARBITRARY CROSS-SECTIONS
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1992 Vol. 14 (4): 396-403
[Abstract]
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1517 )
[PDF 1150KB]
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667
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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...
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Yi Yihong; Li Sifan
ON THE PHASE CENTER OF ELECTROMAGNETIC HORNS
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1992 Vol. 14 (4): 404-408
[Abstract]
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1378 )
[PDF 749KB]
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801
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The characteristics of the phase centers of electromagnetic horns holdingnearly symmetric pattern are presented analytically. It is proved that the phase center on the φ = 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 φ = 45° plane phase center will be the best choice.
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Ding Yaogen
ON OSCILLATIONS IN HIGH POWER KLYSTRONS
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1992 Vol. 14 (4): 409-415
[Abstract]
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1395 )
[PDF 1606KB]
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713
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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 π-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 π-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.
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Liao Guisheng; Jiao Lichen; Bao Zheng
ON STABILITY STUDY OF NEURAL NETWORKS WITH RANDOM PERTURBATION
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1992 Vol. 14 (4): 416-419
[Abstract]
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1410 )
[PDF 692KB]
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700
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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.
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Liang Yingchang; Wang Shuxun; Dai Yisong
AN IMPROVEMENT OF THE RECURSIVE CLOSED-FORM ALGORITHM FOR NON-MINIMUM PHASE FIR SYSTEM IDENTIFICATION
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1992 Vol. 14 (4): 420-423
[Abstract]
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1705 )
[PDF 664KB]
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551
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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.
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Liu Jianzhuang; Tu Yuqing
THRESHOLDING OF IMAGES USING AN EFFICIENT c-MEAN CLUSTERING ALGORITHM
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1992 Vol. 14 (4): 424-427
[Abstract]
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1599 )
[PDF 764KB]
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679
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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.
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Wu Jing①; Zhu Minhui①;Ye Xueqi②
A MODELLING SYSTEM FOR ELECTRONIC STRUCTURES OF MOLECULES
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1992 Vol. 14 (4): 428-431
[Abstract]
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1386 )
[PDF 740KB]
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579
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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.
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Fan Desen; Wang Yuanxun
WAVEGUIDE JUNCTION AND GUIDE-HORN RADIATOR ANALYSIS-GUIDED-WAVE NUMERICAL BOUNDARY CONDITIONS AND THEIR APPLICATIONS
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1992 Vol. 14 (4): 436-440
[Abstract]
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1685 )
[PDF 773KB]
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619
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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.
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Chen Wei
ARRAYS OF UNEQUAL DIPOLES WITH SIMILAR INPUT IMPEDANCES
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1992 Vol. 14 (4): 441-444
[Abstract]
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1483 )
[PDF 676KB]
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606
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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.
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Pan Zongda
THE DEVELOPMENT OF A NEW WAVEGUIDE PHASE SHIFTER
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1992 Vol. 14 (4): 445-448
[Abstract]
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1781 )
[PDF 472KB]
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558
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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.
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