1995 Vol.17 No.3, Published: 19 May 1995
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Wu Xiaopei; Chai Xiaodong; Zhang Delong
THE APPLICATION OF MULTILAYER FEEDFORWARD NETWORK FOR IMAGE SEGMENTATION
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1995 Vol. 17 (3): 225-231
[Abstract]
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1425 )
[PDF 1497KB]
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502
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DOI:
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.
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Lin Sheng; Yin Qinye
SIMPLE ANALYSIS OF THE NEURAL OPTIMIZATION METHOD FOR DOA ESTIMATION
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1995 Vol. 17 (3): 232-237
[Abstract]
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1468 )
[PDF 1112KB]
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626
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DOI:
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.
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Mei Wenhua
THEORETICAL BOUNDS ON FAMILIES OF NONREPEATING FH SEQUENCES
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1995 Vol. 17 (3): 238-242
[Abstract]
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1408 )
[PDF 837KB]
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553
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DOI:
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.
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Wei Ping; Xiao Xianci; Li Lemin
THE FOURTH-ORDER CUMULANTS BASED SPECTRAL ESTIMATION METHOD AND ITS APPLICATION TO DIRECTION-FINDING
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1995 Vol. 17 (3): 243-249
[Abstract]
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1650 )
[PDF 1171KB]
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634
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DOI:
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.
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Wang Weidong; Ke Youan
STUDY ON MATRIX PREDICTION METHOD FOR SIGNAL-POLE ESTIMATION
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1995 Vol. 17 (3): 250-255
[Abstract]
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1682 )
[PDF 1086KB]
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542
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DOI:
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.
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Wu Yirong; Hu Donghui; Peng Hailiang
CHIRP SCALING SAR IMAGING ALGORITHM AND ITS IMPLEMENTATION
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1995 Vol. 17 (3): 256-260
[Abstract]
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1668 )
[PDF 1606KB]
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727
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DOI:
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.
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Kong Junbao①; Liu Mengzhou②
A NEW METHOD FOR IMAGE-VELOCITY COMPUTATION
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1995 Vol. 17 (3): 261-267
[Abstract]
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1537 )
[PDF 1200KB]
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491
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DOI:
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.
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Zhang Linrang; Bao Zheng; Zhang Yuhong
EFFECT OF INTERCHANNEL MISMATCH ON THE SIDELOBE LEVEL OF A DBF ARRAY
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1995 Vol. 17 (3): 268-275
[Abstract]
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1694 )
[PDF 1239KB]
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509
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DOI:
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.
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Yin Wenyan①;Wang Wenbing②
STUDY ON THE CHARACTERISTICS OF HYBRID MODES IN CIRCULAR WAVEGUIDES PARTIALLY FILLED WITH BIANISOTROPIC MEDIUM
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1995 Vol. 17 (3): 276-282
[Abstract]
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1820 )
[PDF 1061KB]
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556
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DOI:
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.
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Yin Liansheng; Hua Guang; Yin Jun
DEVELOPMENT OF TWO WAY ROTARY JOINT WITH WIDE FREQUENCY BAND
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1995 Vol. 17 (3): 291-297
[Abstract]
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1552 )
[PDF 1181KB]
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541
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DOI:
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 λ/4. The structure is simple. Its fabrication and adjustment are easy. And it is light and small. The specified small size requirment is satisfied.
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Lin Shichang①; Zhang Yansheng①; Zhang Guobing②; Wang Yangyuan②
THE GROWTH OF MONOCRYSTALLINE SILICON THIN FILM ON INSULATOR (SOI) BY SCANNING ELECTRON BEAM
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1995 Vol. 17 (3): 298-303
[Abstract]
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1669 )
[PDF 2073KB]
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641
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DOI:
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 200×25μm2.
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Bao Jingfu; Zhu Junfan; Chen Yusheng
STUDY OF Ka-BAND PLL SYSTEM
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1995 Vol. 17 (3): 311-314
[Abstract]
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1627 )
[PDF 676KB]
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661
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DOI:
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.
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Fang Jian; Lin Weigan; Zhao Yushen
NUMERICAL SOLUTION OF THE PARABOLIC EQUATION REPRESENTING ELECTROMAGNETIC WAVE PROPAGATION IN THE TROPOSPHERE USING BOX METHOD
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1995 Vol. 17 (3): 315-320
[Abstract]
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1924 )
[PDF 845KB]
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511
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DOI:
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.
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Feng Dengguo; Xiao Guozhen
CHARACTER OF LINEAR STRUCTURES OF BOOLEAN FUNCTIONS
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1995 Vol. 17 (3): 324-328
[Abstract]
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1545 )
[PDF 780KB]
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520
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DOI:
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.
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Teng Zhimeng; He Ye; Tong Qinyi
THE CROSSWIND EFFECT AND THE SG SCHEME
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1995 Vol. 17 (3): 329-333
[Abstract]
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1537 )
[PDF 913KB]
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514
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DOI:
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.
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