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1993 Vol. 15, No. 1
Display Method:
1993, 15(1): 1-6.
Abstract:
The problem considered in this paper is that of interpolating a virtual uniform linear array from a real two-dimensional array with arbitrary geometry via an interpolation matrix. Central to this problem is how ro place these virtual sensors. It is shown that the virtual uniform linear array should have the same mainlobe beam pattern as the real array over an angular sector of interest. Simulation results are presented to illustrate the application. of virtual array in direction finding.
The problem considered in this paper is that of interpolating a virtual uniform linear array from a real two-dimensional array with arbitrary geometry via an interpolation matrix. Central to this problem is how ro place these virtual sensors. It is shown that the virtual uniform linear array should have the same mainlobe beam pattern as the real array over an angular sector of interest. Simulation results are presented to illustrate the application. of virtual array in direction finding.
1993, 15(1): 7-16.
Abstract:
The logical feature of no-cary operations over GF(2m) and their logical network are discussed, on which generalized S arle operations are defined. The operations are applied to logical fast Walsh transformation over GF(2m), which facilitates further applications of Searle operations in sequence theory.
The logical feature of no-cary operations over GF(2m) and their logical network are discussed, on which generalized S arle operations are defined. The operations are applied to logical fast Walsh transformation over GF(2m), which facilitates further applications of Searle operations in sequence theory.
1993, 15(1): 17-25.
Abstract:
There are many kinds of special relationships between multiple-valued logical functions and their variables, and it is difficult to be judged from their expressions . In this paper, some sufficient and necessary conditions of the independence and statistical indepenndence of multiple-valued logical functions from their variables are given. Some conditions of algebraic independence of multi-valued logical functions from some of their variables and the way to degenerate a function to the greatest extent are proposed, and some applications of these results are indicated. All the results are studied by using Chrestenson spectral techniques.
There are many kinds of special relationships between multiple-valued logical functions and their variables, and it is difficult to be judged from their expressions . In this paper, some sufficient and necessary conditions of the independence and statistical indepenndence of multiple-valued logical functions from their variables are given. Some conditions of algebraic independence of multi-valued logical functions from some of their variables and the way to degenerate a function to the greatest extent are proposed, and some applications of these results are indicated. All the results are studied by using Chrestenson spectral techniques.
1993, 15(1): 26-32.
Abstract:
On the basis of target transfer function with the early-time and later-time responses together, a method for solving the target feature coefficients is investigated by utilizing the approximation theory and method. Then, the feature coefficients are classified by the minimum distance criterion to recognize the target automatically.
On the basis of target transfer function with the early-time and later-time responses together, a method for solving the target feature coefficients is investigated by utilizing the approximation theory and method. Then, the feature coefficients are classified by the minimum distance criterion to recognize the target automatically.
1993, 15(1): 33-37.
Abstract:
The Lindell formulation based on the generalized variational principle is derived, and an accurate variational analytical result of the measurement of the complex dielectric constant by the Rayleigh-Ritz method is obtained when the loss is small. The concept of the complex frequency is introduced in a com non case, and also touched on the stationarity of the solution, then compared the results with he pertubational result. It is demonstrated with these results that it is necessary to pay attention to the Theortical error of pertubational method.
The Lindell formulation based on the generalized variational principle is derived, and an accurate variational analytical result of the measurement of the complex dielectric constant by the Rayleigh-Ritz method is obtained when the loss is small. The concept of the complex frequency is introduced in a com non case, and also touched on the stationarity of the solution, then compared the results with he pertubational result. It is demonstrated with these results that it is necessary to pay attention to the Theortical error of pertubational method.
1993, 15(1): 38-44.
Abstract:
The characteristics of the cyclotron autoresonance maser with a large-orbit electron ring in a partially dielectric-loaded waveguide have been analyzed by making use of the linearized Vlasov- Maxweil equations. The results show that the dielectric liner can reduce the energy of ekctron beam, and a novel radiation source can be made in the millimeter and submilimeter waveband by using this method.
The characteristics of the cyclotron autoresonance maser with a large-orbit electron ring in a partially dielectric-loaded waveguide have been analyzed by making use of the linearized Vlasov- Maxweil equations. The results show that the dielectric liner can reduce the energy of ekctron beam, and a novel radiation source can be made in the millimeter and submilimeter waveband by using this method.
1993, 15(1): 45-51.
Abstract:
To solve the problem of reconstructing profiles of layered media (RPLM), at first a new time-domain mathematical model for EM wave propagation in lavered media is presented. Secondly, the problem for RPLM is reduced to a paramerer identification one with distributed parameter system. Then a new effective method of RPLM is presented. The method is better than the reconstruction method using reflection coefficient or impluse response to inverse its potential function. A fast identification algorithm is obtained by making use of the step-gradient layered inversion method. Finally, a digital simulation example shows the feasibility of the algorithm.
To solve the problem of reconstructing profiles of layered media (RPLM), at first a new time-domain mathematical model for EM wave propagation in lavered media is presented. Secondly, the problem for RPLM is reduced to a paramerer identification one with distributed parameter system. Then a new effective method of RPLM is presented. The method is better than the reconstruction method using reflection coefficient or impluse response to inverse its potential function. A fast identification algorithm is obtained by making use of the step-gradient layered inversion method. Finally, a digital simulation example shows the feasibility of the algorithm.
1993, 15(1): 52-59.
Abstract:
Formulas for the elastic and coherent inelastic scattering be an arbitrary body uniformly filled with active molecules are presentd with the method of eigenfunction expansion in the integral equation for scattering by dielectric body Agreement between the formulas obtained for the elastic scattering by an arbitrary body and those in the previous literatures illustrates the formulas here are not restricted tc the situation of weak scatterring. Some numerical results for the coherent inelastic scattering by an ellipsoid uniformly filled with active mole- cules are given here.
Formulas for the elastic and coherent inelastic scattering be an arbitrary body uniformly filled with active molecules are presentd with the method of eigenfunction expansion in the integral equation for scattering by dielectric body Agreement between the formulas obtained for the elastic scattering by an arbitrary body and those in the previous literatures illustrates the formulas here are not restricted tc the situation of weak scatterring. Some numerical results for the coherent inelastic scattering by an ellipsoid uniformly filled with active mole- cules are given here.
1993, 15(1): 75-78.
Abstract:
It is an active researching area to reconstruct the model of 3-dimensional object from cross-sectional images and to display its visible surfaces. In this paper, the theory and the method of reconstructing the model of 3-D object and displaving its visible surface from X-CT imaqes are studied. Giving the number of segment points, a polygonal approximation method is presented. Then a fast contour interpolating method is introduced. The reconstructed liver voxel set is displayed with the depth-only shading method and the depth gradient shading method, the result is satisfactory. The software is written in C language and runs on PC-VISION image processing system.
It is an active researching area to reconstruct the model of 3-dimensional object from cross-sectional images and to display its visible surfaces. In this paper, the theory and the method of reconstructing the model of 3-D object and displaving its visible surface from X-CT imaqes are studied. Giving the number of segment points, a polygonal approximation method is presented. Then a fast contour interpolating method is introduced. The reconstructed liver voxel set is displayed with the depth-only shading method and the depth gradient shading method, the result is satisfactory. The software is written in C language and runs on PC-VISION image processing system.
1993, 15(1): 79-82.
Abstract:
A nonideal second current conveyer (NCCII) is described. The circuit of NCCII constructed with operational transconductance amplifers (OTA) only is proposed. The current conveyer of this used as a circuit building block to realize capacitor and resistance converters is also reported.
A nonideal second current conveyer (NCCII) is described. The circuit of NCCII constructed with operational transconductance amplifers (OTA) only is proposed. The current conveyer of this used as a circuit building block to realize capacitor and resistance converters is also reported.
1993, 15(1): 83-87.
Abstract:
Based on L. F. Wei s work (1984), the generalized trellis diagram oftrellis codes is defined, then the properties of rotationally invariant trellis codes with two-dimensional QAM constellations are discussed, and all the unequivalent signal assignments are given. Finally, rotationally invariant trellis codes are designed easily.
Based on L. F. Wei s work (1984), the generalized trellis diagram oftrellis codes is defined, then the properties of rotationally invariant trellis codes with two-dimensional QAM constellations are discussed, and all the unequivalent signal assignments are given. Finally, rotationally invariant trellis codes are designed easily.
1993, 15(1): 88-91.
Abstract:
Modified Cassegrainian antenna with polarization rotator has been widely used in the airborne radar systems because of its electrical and structural advantages. Up to now, however, the scattering aspect of this antenna has not been systematically investigated theroe-tically and experimentally. In this paper, the radar cross-section (RCS) of this antenna under the incidence of EM waves of various frequencies and polarizations is evaluated based on antenna scattering theory. The numerical results show that this kind of antenna contributes a substantial RCS in the nose-on region, and it will be quite a difficult task to reduce its RCS contribution without- degradation of antenna performances.
Modified Cassegrainian antenna with polarization rotator has been widely used in the airborne radar systems because of its electrical and structural advantages. Up to now, however, the scattering aspect of this antenna has not been systematically investigated theroe-tically and experimentally. In this paper, the radar cross-section (RCS) of this antenna under the incidence of EM waves of various frequencies and polarizations is evaluated based on antenna scattering theory. The numerical results show that this kind of antenna contributes a substantial RCS in the nose-on region, and it will be quite a difficult task to reduce its RCS contribution without- degradation of antenna performances.
1993, 15(1): 92-97.
Abstract:
The Green s functions for electr ic and magnetic vector potentials in a sectoral wave guide and its cavity are derivated by using the separation of variables, Fourier transform and residue theory.
The Green s functions for electr ic and magnetic vector potentials in a sectoral wave guide and its cavity are derivated by using the separation of variables, Fourier transform and residue theory.
1993, 15(1): 98-102.
Abstract:
The measurement of reflection from an open-ended coaxial line is a simple and nondestructive technique of determining the dielectric property of materials. The electromagnetic field in the vicinity of the aperture is studied by means of rigorous field matching method. The reflection coefficient is computed by moment method as a function of the dielectric constant. The validity of the theoretical results is ested by comparing the numerical evaluation with previous paper. Furthermore, a method fo data inversion is provided.
The measurement of reflection from an open-ended coaxial line is a simple and nondestructive technique of determining the dielectric property of materials. The electromagnetic field in the vicinity of the aperture is studied by means of rigorous field matching method. The reflection coefficient is computed by moment method as a function of the dielectric constant. The validity of the theoretical results is ested by comparing the numerical evaluation with previous paper. Furthermore, a method fo data inversion is provided.
1993, 15(1): 103-107.
Abstract:
The applicability of the assumption, the surface photo-voltage is a monotonic function of the surface excess minority carrier density, to epitaxial material is studied by numerical analysis method. It is found that this assumption is unreasonable for epitaxial material in general. Therefore when the minority carrier diffusion length in epitaxial material is measured by the equal-surface-photo-voltage method, the surface excess minority carrier density should not be considered as a constant. In this paper,the condition under which the surface excess minority carrier density may be treated as a constant is also analysed.
The applicability of the assumption, the surface photo-voltage is a monotonic function of the surface excess minority carrier density, to epitaxial material is studied by numerical analysis method. It is found that this assumption is unreasonable for epitaxial material in general. Therefore when the minority carrier diffusion length in epitaxial material is measured by the equal-surface-photo-voltage method, the surface excess minority carrier density should not be considered as a constant. In this paper,the condition under which the surface excess minority carrier density may be treated as a constant is also analysed.
1993, 15(1): 108-112.
Abstract:
The magnetic detector made of aamorphous soft magnetic film cores has better characteristics. Experimental results indicate that the detector has a good linear relation between the double-frequency single voltage output and the magnetic field, a magnetic resolution of 10-10--10-11T, and a temperature coefficient of 0.05%/℃ between －40--120℃, The magnetic resolution of the detector increases with lengthening the core, but it is independent of the width and thickness of the core in a certain range. This kind of detector compared with the detector using polycrystal soft magnetic thin film has many advantages, such as smaller side, better durability, stability and temperature characteristic.
The magnetic detector made of aamorphous soft magnetic film cores has better characteristics. Experimental results indicate that the detector has a good linear relation between the double-frequency single voltage output and the magnetic field, a magnetic resolution of 10-10--10-11T, and a temperature coefficient of 0.05%/℃ between －40--120℃, The magnetic resolution of the detector increases with lengthening the core, but it is independent of the width and thickness of the core in a certain range. This kind of detector compared with the detector using polycrystal soft magnetic thin film has many advantages, such as smaller side, better durability, stability and temperature characteristic.
1993, 15(1): 60-68.
Abstract:
Progress in the research area of photoconductive semiconductor switches is reviewed. The recent development of photoconductive materials, the generation of high-power pulse and its application, the measurement technology using ultrashort electromagnetic pulse are presented.
Progress in the research area of photoconductive semiconductor switches is reviewed. The recent development of photoconductive materials, the generation of high-power pulse and its application, the measurement technology using ultrashort electromagnetic pulse are presented.
1993, 15(1): 69-74.
Abstract:
The field of low-noise elecronics and noise circuit theory are described svntheti-cally. Some imperfections of the current noise circuit theories are pointed out. And the research direction and the methods of development of noise circuit theory and noise performances are also presented.
The field of low-noise elecronics and noise circuit theory are described svntheti-cally. Some imperfections of the current noise circuit theories are pointed out. And the research direction and the methods of development of noise circuit theory and noise performances are also presented.
