Email alert
1990 Vol. 12, No. 4
Display Method:
1990, 12(4): 337-343.
Abstract:
Linear octrees offer a volume representation of 3-Dobjects, which is quite compact and lends itself to traditional object processing operations. However, the linear octree structure for generating the representation of 3-D objects from three orthogonal views by using the volume intersection technique is dependent on viewpoints. The recognition achieved from matching object representations to model representations requires that the representalions of objects are independent on viewpoints. In order to obtain independent representations on viewpoint, the three principal axes of the object should be found frm the moment of inertia matrix by computing its eigenvectors. The linear octree is projected onto the image planes of the three principal views (along the principal axes) to obtain the three nomalized linear quadtrees. The object marching procedure has two phases: the first phase is to mtch the normalized ,linear quadtrees of the unknown object to a subset of models contained in .a library, utilizing a measure of symmetric difference; the second phase is to generate the normalized linear octrees of the object and these selected models and then match the normalized linear octree of the unknown object to the model with the minimum symmetric difference.
Linear octrees offer a volume representation of 3-Dobjects, which is quite compact and lends itself to traditional object processing operations. However, the linear octree structure for generating the representation of 3-D objects from three orthogonal views by using the volume intersection technique is dependent on viewpoints. The recognition achieved from matching object representations to model representations requires that the representalions of objects are independent on viewpoints. In order to obtain independent representations on viewpoint, the three principal axes of the object should be found frm the moment of inertia matrix by computing its eigenvectors. The linear octree is projected onto the image planes of the three principal views (along the principal axes) to obtain the three nomalized linear quadtrees. The object marching procedure has two phases: the first phase is to mtch the normalized ,linear quadtrees of the unknown object to a subset of models contained in .a library, utilizing a measure of symmetric difference; the second phase is to generate the normalized linear octrees of the object and these selected models and then match the normalized linear octree of the unknown object to the model with the minimum symmetric difference.
1990, 12(4): 344-351.
Abstract:
Starting from an index mapping for one to multi-dimensions, a general in-place and in-order prime factor FFT algorithm is proposed. Comparing with existing prime factor FFT algorithms, this algorithm saves about half of the storage and possesses a higher efficiency. In addition, this algorithm can easily implement the DFT and 1DFT in a single subroutine.
Starting from an index mapping for one to multi-dimensions, a general in-place and in-order prime factor FFT algorithm is proposed. Comparing with existing prime factor FFT algorithms, this algorithm saves about half of the storage and possesses a higher efficiency. In addition, this algorithm can easily implement the DFT and 1DFT in a single subroutine.
1990, 12(4): 352-360.
Abstract:
A new generalized measurement equation for multi-port lossless network is developed. In two-port case, it is reduced as a triangle function in the paper [1]. As an example, expefemental data are given for a H-plane T three-port network.
A new generalized measurement equation for multi-port lossless network is developed. In two-port case, it is reduced as a triangle function in the paper [1]. As an example, expefemental data are given for a H-plane T three-port network.
1990, 12(4): 361-368.
Abstract:
The calculation formulas of monostatic radar cross-section (RCS) of arbitrary reflectors with arbitrarily polarized plane-wave incidence are derived, where the specular field is obtained by geometrical optics and the edge-diffracted field is calculated by the method of equivalent currents (MEC). Some typical results calculated are given by means of RCS spatial graphs. For both horizontal and vertical polarizations, the theoretical results obtained in this paper agree very well with the experimental results as well as the results from uniform theory of diffraction.
The calculation formulas of monostatic radar cross-section (RCS) of arbitrary reflectors with arbitrarily polarized plane-wave incidence are derived, where the specular field is obtained by geometrical optics and the edge-diffracted field is calculated by the method of equivalent currents (MEC). Some typical results calculated are given by means of RCS spatial graphs. For both horizontal and vertical polarizations, the theoretical results obtained in this paper agree very well with the experimental results as well as the results from uniform theory of diffraction.
1990, 12(4): 369-377.
Abstract:
A new type of current model, defined as node nuit current model, for calculating current distribution on arbitrary shape conductors is presented. By using this model, the number of unknowns necessary for MM solution of current distribution is decreased greatly. The current solutions for typical problems are given. They are in agreement with those obtained by exact formulas and other approaches.
A new type of current model, defined as node nuit current model, for calculating current distribution on arbitrary shape conductors is presented. By using this model, the number of unknowns necessary for MM solution of current distribution is decreased greatly. The current solutions for typical problems are given. They are in agreement with those obtained by exact formulas and other approaches.
1990, 12(4): 378-384.
Abstract:
An improved perturbation procedure is used for analysing the radiation characteristics of the millimeter wave dielectric leaky wave grating antenna. The electromagnetic fields are described in terms of a transverse transmission line network, which brings considerable physical insight into the overall behavior of the antenna. The analysis is simple and practical. Its accuracy is as high as the rigorous method.
An improved perturbation procedure is used for analysing the radiation characteristics of the millimeter wave dielectric leaky wave grating antenna. The electromagnetic fields are described in terms of a transverse transmission line network, which brings considerable physical insight into the overall behavior of the antenna. The analysis is simple and practical. Its accuracy is as high as the rigorous method.
1990, 12(4): 385-392.
Abstract:
A system is presented in which the equivalent lumped circuit approach and S parameter approach are in conjunction with the electromagnetic field analysis on dielectric resonator (DR) coupling with microstrip. Theoretical calculations agree well with experimental results. Some discussion on optically controlled DR oscillator and box are also given.
A system is presented in which the equivalent lumped circuit approach and S parameter approach are in conjunction with the electromagnetic field analysis on dielectric resonator (DR) coupling with microstrip. Theoretical calculations agree well with experimental results. Some discussion on optically controlled DR oscillator and box are also given.
1990, 12(4): 393-401.
Abstract:
A new method, termed netwok model decomposition method, is presented for the evaluation of cut-off frequencies of an arbitrary shaped waveguide with arbitrary filling. Through discreting the region studied, a topological model and the corresponding network model are established based on the differential orms in electromagnetic field theory. A general algorithm for evaluating the cut-off frequenciess of an arbitrary shaped waveguide with arbitrary filling is constructed by using the diakopti node analysis in electrical network theory. The algorithm is applied to several typical waveguides with the validity and effectiveness of the method demonstrated.
A new method, termed netwok model decomposition method, is presented for the evaluation of cut-off frequencies of an arbitrary shaped waveguide with arbitrary filling. Through discreting the region studied, a topological model and the corresponding network model are established based on the differential orms in electromagnetic field theory. A general algorithm for evaluating the cut-off frequenciess of an arbitrary shaped waveguide with arbitrary filling is constructed by using the diakopti node analysis in electrical network theory. The algorithm is applied to several typical waveguides with the validity and effectiveness of the method demonstrated.
1990, 12(4): 402-414.
Abstract:
The misalignment assembling error effect of lenses and deflectors and its evaluation in electron beam focusing and deflection systems are discussed. First the electrostatic and magnetic field expression in electron beam systems due to the misaligned lenses and deflectors are derived. Then the formulae for evaluating the changes of the optical properties caused by the misalignment assembling errors (i.e. the additional image shifting and additional aberrations) are given by the derived field expression and the general ray equation. A set of programs based on the fromulae given is developed, and some illustrative examples are also shown as the spot-diagrams. It can be reflected that the numerical computation of the misalignment assembling error effect plays important role in both designing and assembling electron beam focusing and deflection systems.
The misalignment assembling error effect of lenses and deflectors and its evaluation in electron beam focusing and deflection systems are discussed. First the electrostatic and magnetic field expression in electron beam systems due to the misaligned lenses and deflectors are derived. Then the formulae for evaluating the changes of the optical properties caused by the misalignment assembling errors (i.e. the additional image shifting and additional aberrations) are given by the derived field expression and the general ray equation. A set of programs based on the fromulae given is developed, and some illustrative examples are also shown as the spot-diagrams. It can be reflected that the numerical computation of the misalignment assembling error effect plays important role in both designing and assembling electron beam focusing and deflection systems.
1990, 12(4): 415-417.
Abstract:
C-V and I-V characteristics of ultratllin metal/LB insulating films/semiconductor structure are studied. Theoretical analysis are well in accord with experimental results. The results indicate that: (1) Ultrathin MLS structure has normal C-V and I-V characteristics; (2) It is possible to modify the barrier height of Schottky devices by using LB thin films as insulators.
C-V and I-V characteristics of ultratllin metal/LB insulating films/semiconductor structure are studied. Theoretical analysis are well in accord with experimental results. The results indicate that: (1) Ultrathin MLS structure has normal C-V and I-V characteristics; (2) It is possible to modify the barrier height of Schottky devices by using LB thin films as insulators.
1990, 12(4): 418-423.
Abstract:
The emission and surface characteristics of a dispenser cathode coaled with Re are studied. It is found that the dispenser cathode coated with Re has both higher current density and more uniform distribution of emission than the S type cathode. The Auger images of Ba show tha: the Ba distribution on the surface of the cathode coated with Re is more uniform than that on the surface of the S type cathode. The analytical results by XPS and low energy AES show that the Ba on the surface of the cathode coated with Re has stronger metallic property than thar on the surface of the S type cathode.
The emission and surface characteristics of a dispenser cathode coaled with Re are studied. It is found that the dispenser cathode coated with Re has both higher current density and more uniform distribution of emission than the S type cathode. The Auger images of Ba show tha: the Ba distribution on the surface of the cathode coated with Re is more uniform than that on the surface of the S type cathode. The analytical results by XPS and low energy AES show that the Ba on the surface of the cathode coated with Re has stronger metallic property than thar on the surface of the S type cathode.
1990, 12(4): 424-430.
Abstract:
By introducing a parameter, which is the length of the voltage-current characteristic curve of piecewise-linear resistor, into the description of the characteristics of the resistor, it is possible to analyze a piecewise linear resistive network topologically. By means of the method presented here, some shortcomings of current methods when they are used to analyze a network including neither-voltage-controlled-nor-current-controlled resistors can be avoided.
By introducing a parameter, which is the length of the voltage-current characteristic curve of piecewise-linear resistor, into the description of the characteristics of the resistor, it is possible to analyze a piecewise linear resistive network topologically. By means of the method presented here, some shortcomings of current methods when they are used to analyze a network including neither-voltage-controlled-nor-current-controlled resistors can be avoided.
1990, 12(4): 431-435.
Abstract:
A new texture analysis method on image-fast eigenfiltering method is presented.Based on eigenfilters proposed by Ade, with which the eigenvalues of the real symmetric matrix represent distribution of the eigenvectors related to the matrix, and by using associative law of convolution, the fast eigenfilters are derived. In fast eigenfiltering method, n n eigenfilters in Ade s filtering method merge into one filter, which can speed up the computation and reduces memory space.
A new texture analysis method on image-fast eigenfiltering method is presented.Based on eigenfilters proposed by Ade, with which the eigenvalues of the real symmetric matrix represent distribution of the eigenvectors related to the matrix, and by using associative law of convolution, the fast eigenfilters are derived. In fast eigenfiltering method, n n eigenfilters in Ade s filtering method merge into one filter, which can speed up the computation and reduces memory space.
1990, 12(4): 436-439.
Abstract:
The (n, F, k) system consists of n components. If the number of failed component is more than F, or the number of adjacent failed component is more than K, tken the system fails. A recursive formula for computing reliability of the system is presented, and the up and low bound of reliability of this system are given.
The (n, F, k) system consists of n components. If the number of failed component is more than F, or the number of adjacent failed component is more than K, tken the system fails. A recursive formula for computing reliability of the system is presented, and the up and low bound of reliability of this system are given.
1990, 12(4): 440-445.
Abstract:
The equivalent series reactance and parallel susceptance of a small conclucring foreign body in the rectangular waveguides are derived by using perturbational formula in the rectangular cavity and combining with quasi-static approximation. The expressions of its reflection coefficient, transmission phase displacement and power carrying capacity reduction are also given. The expressions are shown that is satisfactory in experiment.
The equivalent series reactance and parallel susceptance of a small conclucring foreign body in the rectangular waveguides are derived by using perturbational formula in the rectangular cavity and combining with quasi-static approximation. The expressions of its reflection coefficient, transmission phase displacement and power carrying capacity reduction are also given. The expressions are shown that is satisfactory in experiment.
1990, 12(4): 446-448.
Abstract:
In the surface analysis and the manufacture of photocathode the cesium ion source shows some advantages as compared with the neutral cesium source. According to the principle of surface ionization, a cesium ion source is manufactured with porous tungsten and cesium chromate. A tablet of porous tungsten and a nickel tube are welded by a laser beam. The ion source is heated to about 1000K io terms of an indirect heating oven and its experimental results are given.
In the surface analysis and the manufacture of photocathode the cesium ion source shows some advantages as compared with the neutral cesium source. According to the principle of surface ionization, a cesium ion source is manufactured with porous tungsten and cesium chromate. A tablet of porous tungsten and a nickel tube are welded by a laser beam. The ion source is heated to about 1000K io terms of an indirect heating oven and its experimental results are given.
