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1995 Vol. 17, No. 3
Display Method:
1995, 17(3): 225-231.
Abstract:
The Multilayer feedforward network is used for image segmentation. The procedure of achieving learning patterns and the method of improving the leaning rate are discussed. The experiment shows that using the multilayer feedforward network for image segmentation can get good results.
The Multilayer feedforward network is used for image segmentation. The procedure of achieving learning patterns and the method of improving the leaning rate are discussed. The experiment shows that using the multilayer feedforward network for image segmentation can get good results.
1995, 17(3): 232-237.
Abstract:
This paper gives a simple analysis of the method of using the Hop-field s optimization neural network to solve the DOA estimation problem. Although the method can avoid the eigendecomposition of data autocorrelation matrix and the orthogonality search of parameter space, theoretical analysis and simulation results show that the construction of the DOA cost function is incorrect on the condition that there is no constraint on the number of outputs of the network.
This paper gives a simple analysis of the method of using the Hop-field s optimization neural network to solve the DOA estimation problem. Although the method can avoid the eigendecomposition of data autocorrelation matrix and the orthogonality search of parameter space, theoretical analysis and simulation results show that the construction of the DOA cost function is incorrect on the condition that there is no constraint on the number of outputs of the network.
1995, 17(3): 238-242.
Abstract:
Theoretical bounds are given for the number and period of nonrepea, ting Frequency Hopping (FH) sequences in asynchronous frequency hopping multiple access, with a guaranteed maximum number of pairwise hits. Practical constructions for families of nonrepeating sequences which reach the theoretical bounds are also given in this paper.
Theoretical bounds are given for the number and period of nonrepea, ting Frequency Hopping (FH) sequences in asynchronous frequency hopping multiple access, with a guaranteed maximum number of pairwise hits. Practical constructions for families of nonrepeating sequences which reach the theoretical bounds are also given in this paper.
THE FOURTH-ORDER CUMULANTS BASED SPECTRAL ESTIMATION METHOD AND ITS APPLICATION TO DIRECTION-FINDING
1995, 17(3): 243-249.
Abstract:
Traditional approaches of spatial spectral estimation are usually based on the second-order statistics. The higher-order cumulants and the poly-spectrum have more information and are capable to reduce the Gaussian noises. In this paper, a kind of spectrum estimation method for direction-finding is presented based on the eigen-structure analysis of the fourth-order cumulants. The algorithm is derived and its performance is illustrated by both the computer simulations and the experiments of the direction-finding system. The obtained results demonstrate that the fourthorder cumumlant-based method outperforms the traditional direction-finding method, especially when the noise is unknown coloured one.
Traditional approaches of spatial spectral estimation are usually based on the second-order statistics. The higher-order cumulants and the poly-spectrum have more information and are capable to reduce the Gaussian noises. In this paper, a kind of spectrum estimation method for direction-finding is presented based on the eigen-structure analysis of the fourth-order cumulants. The algorithm is derived and its performance is illustrated by both the computer simulations and the experiments of the direction-finding system. The obtained results demonstrate that the fourthorder cumumlant-based method outperforms the traditional direction-finding method, especially when the noise is unknown coloured one.
1995, 17(3): 250-255.
Abstract:
A systematic study of matrix prediction method for signal-pole estimation and equations of forward, backward and forward-backward matrix prediction are presented. The relationship between matrix prediction method and linear prediction method is proposed further. The simulation results are shown for illustrating the efficiency of matrix prediction method.
A systematic study of matrix prediction method for signal-pole estimation and equations of forward, backward and forward-backward matrix prediction are presented. The relationship between matrix prediction method and linear prediction method is proposed further. The simulation results are shown for illustrating the efficiency of matrix prediction method.
1995, 17(3): 256-260.
Abstract:
This paper improves the model of Chirp Scaling (CS) SAR imaging algorithm. Based on the theoretical analysis, the exact formulation of point target in two-dimensional frequency domain and the phase error are obtained. According to the characteristics of the CS algorithm, a hardware architecture to realize its realtime imaging processing is provided.
This paper improves the model of Chirp Scaling (CS) SAR imaging algorithm. Based on the theoretical analysis, the exact formulation of point target in two-dimensional frequency domain and the phase error are obtained. According to the characteristics of the CS algorithm, a hardware architecture to realize its realtime imaging processing is provided.
1995, 17(3): 261-267.
Abstract:
A new method for image-velocity computation is described. If the image area is known, then by using a set of intersecting delay lines, the two perpendicular components of image velocity can be analysed and computed, but if the image area is not knows, then two sets of intersecting delay lines are required. This method is a suitable tool for simulating very large-scale integrated circuits.
A new method for image-velocity computation is described. If the image area is known, then by using a set of intersecting delay lines, the two perpendicular components of image velocity can be analysed and computed, but if the image area is not knows, then two sets of intersecting delay lines are required. This method is a suitable tool for simulating very large-scale integrated circuits.
1995, 17(3): 268-275.
Abstract:
This paper discusses the effect of impulse response aberration between channels on the sidelobe level of a DBF array, and then derives the relationship between the frequency response mismatch and the impulse response aberration of a channel, by which the effect of frequency response mismatch between channels on the antenna sidelobe level is acquired. It shows that frequency response mismatch degrades sidelobe considerablely. Finally, the results by computer simulations are demonstrated.
This paper discusses the effect of impulse response aberration between channels on the sidelobe level of a DBF array, and then derives the relationship between the frequency response mismatch and the impulse response aberration of a channel, by which the effect of frequency response mismatch between channels on the antenna sidelobe level is acquired. It shows that frequency response mismatch degrades sidelobe considerablely. Finally, the results by computer simulations are demonstrated.
1995, 17(3): 276-282.
Abstract:
A new kind of bianisotropic waveguide structure is introduced. In such complex waveguide, the transverse field components can also be expressed in terms of their longitudinal electric and magnetic fields, and a set of coupled mode equations is derived. The bifurcation effect, dispersion characteristics as well as field distribution of hybrid modes in bianisotropic central loaded-metallic circular waveguide are investigated. The numerical results show that because of the introducing of many electromagnetic parameters, bianisotropic waveguides possess some features, which can be used to design novel microwave, millimeter wave and optical devices.
A new kind of bianisotropic waveguide structure is introduced. In such complex waveguide, the transverse field components can also be expressed in terms of their longitudinal electric and magnetic fields, and a set of coupled mode equations is derived. The bifurcation effect, dispersion characteristics as well as field distribution of hybrid modes in bianisotropic central loaded-metallic circular waveguide are investigated. The numerical results show that because of the introducing of many electromagnetic parameters, bianisotropic waveguides possess some features, which can be used to design novel microwave, millimeter wave and optical devices.
1995, 17(3): 283-290.
Abstract:
A new method, the optimized simulated image method in combination with conformal mapping, is introduced to calculate the characteristic impedance of arbitrarily shaped coaxial transmission lines. It is of small calculating amount and high accuracy, and the error range can also be estimated. The calculating results of the characteristic impedances of nine coaxial lines, such as concentric, eccentric circular inner and square outer conductors, strip inner and circular outer conductors, are tabulated and compared with data from other papers.
A new method, the optimized simulated image method in combination with conformal mapping, is introduced to calculate the characteristic impedance of arbitrarily shaped coaxial transmission lines. It is of small calculating amount and high accuracy, and the error range can also be estimated. The calculating results of the characteristic impedances of nine coaxial lines, such as concentric, eccentric circular inner and square outer conductors, strip inner and circular outer conductors, are tabulated and compared with data from other papers.
1995, 17(3): 291-297.
Abstract:
A wide frequency band two-way rotary joint (in the same frequency band) is described. Its VSWR is less than 1.3 over the frequency range from 0.7 GHz to 1.4GHz, its insert loss is less than 0.50dB, its isolation is better than 40dB. The rotary joint uses two symmetic excitation points and muff structure, and its length is shorter than /4. The structure is simple. Its fabrication and adjustment are easy. And it is light and small. The specified small size requirment is satisfied.
A wide frequency band two-way rotary joint (in the same frequency band) is described. Its VSWR is less than 1.3 over the frequency range from 0.7 GHz to 1.4GHz, its insert loss is less than 0.50dB, its isolation is better than 40dB. The rotary joint uses two symmetic excitation points and muff structure, and its length is shorter than /4. The structure is simple. Its fabrication and adjustment are easy. And it is light and small. The specified small size requirment is satisfied.
1995, 17(3): 298-303.
Abstract:
An experiment for preparation of SOI films by using scanning electron beam to modify polycrystalline silicon on SiO2 is presented. This method takes on the lateral epitaxial growth of liquid phase crystallon to form monocrystal Si films. The effects of beam power density, scanning velocity, temperature of substrates and the construction of samples on the quality of the monocrystalline silicon films were discussed. A good experimental result has been obtained, the mono-crystalline silicon zone is nearly 20025m2.
An experiment for preparation of SOI films by using scanning electron beam to modify polycrystalline silicon on SiO2 is presented. This method takes on the lateral epitaxial growth of liquid phase crystallon to form monocrystal Si films. The effects of beam power density, scanning velocity, temperature of substrates and the construction of samples on the quality of the monocrystalline silicon films were discussed. A good experimental result has been obtained, the mono-crystalline silicon zone is nearly 20025m2.
1995, 17(3): 304-310.
Abstract:
A new algorithm of calculating depth information by image sequences acquired from the parallel multi-viewpoints is discussed. By means of orthogonal transformation of image (in this paper, the authors use fast Fourier transformation), the matching problem, which is difficult to solve in time domain, is put into transformation field in frequency domain.
A new algorithm of calculating depth information by image sequences acquired from the parallel multi-viewpoints is discussed. By means of orthogonal transformation of image (in this paper, the authors use fast Fourier transformation), the matching problem, which is difficult to solve in time domain, is put into transformation field in frequency domain.
1995, 17(3): 311-314.
Abstract:
An 8mm wave PLL system is designed and manufactured by use of multi-loops. It is measured that the phase noise of mm-wave PLL source is-78dBc/ Hz (Fourier frequency is 1kHz offset carrier 37.4 GHz), spurious is lower than-60 dBc, output power is higher than 40mW.
An 8mm wave PLL system is designed and manufactured by use of multi-loops. It is measured that the phase noise of mm-wave PLL source is-78dBc/ Hz (Fourier frequency is 1kHz offset carrier 37.4 GHz), spurious is lower than-60 dBc, output power is higher than 40mW.
1995, 17(3): 315-320.
Abstract:
An implicit finite-difference (IFD) scheme of box method is introduced for solving the parabolic equation representing electromagnetic wave propagation in the troposphere. The consistency, stability and convergence of the box method is demonstrated. More accurate results are obtained while the modified refrac-tivity varies both with the height and the distance. Compared with the popular used Fourier split-step method, the box method has the advantage of having more accurate results and solving boundary conditions casier.
An implicit finite-difference (IFD) scheme of box method is introduced for solving the parabolic equation representing electromagnetic wave propagation in the troposphere. The consistency, stability and convergence of the box method is demonstrated. More accurate results are obtained while the modified refrac-tivity varies both with the height and the distance. Compared with the popular used Fourier split-step method, the box method has the advantage of having more accurate results and solving boundary conditions casier.
1995, 17(3): 321-323.
Abstract:
By using electromagnentism relativity transformation method, the propagation properties of EM mode of nonlinear slab optical waveguide in moving were studied. The results in moving reference system and in laboratory reference system were compared.
By using electromagnentism relativity transformation method, the propagation properties of EM mode of nonlinear slab optical waveguide in moving were studied. The results in moving reference system and in laboratory reference system were compared.
1995, 17(3): 324-328.
Abstract:
The linear structures of Boolean functions are discussed using characteristic set of Boolean functions, and a way to find linear structures of Boolean functions is given. Then, the linear structures of Boolean functions are generalized, and r-type linear structures of Boolean functions are presented and studied, meanwhile the cryptological significance of r-type linear structures of Boolean functions is described.
The linear structures of Boolean functions are discussed using characteristic set of Boolean functions, and a way to find linear structures of Boolean functions is given. Then, the linear structures of Boolean functions are generalized, and r-type linear structures of Boolean functions are presented and studied, meanwhile the cryptological significance of r-type linear structures of Boolean functions is described.
1995, 17(3): 329-333.
Abstract:
This paper analyzes the cause of the crosswind effect inherent in the SG scheme and its influence on the SG scheme. It provides the basis for the application of the SG scheme.
This paper analyzes the cause of the crosswind effect inherent in the SG scheme and its influence on the SG scheme. It provides the basis for the application of the SG scheme.
1995, 17(3): 334-336.
Abstract:
The deep levels in electron irradiated CZ silicon single crystal grown in pure nitrogen protective atmosphere has been studied. It is pointed out that there is no measurable deep level related to nitrogen.
The deep levels in electron irradiated CZ silicon single crystal grown in pure nitrogen protective atmosphere has been studied. It is pointed out that there is no measurable deep level related to nitrogen.
