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1992 Vol. 14, No. 4
Display Method:
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 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
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...
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...
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...
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...
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 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.
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.
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.
