Email alert
2000 Vol. 22, No. 4
Display Method:
2000, 22(4): 529-535.
Abstract:
Quasar Objects (QSOs) are detectable at very large distance,with broad,red-shifted emission lines,strong ultraviolet and strong time variability of the optical light.QSOs play an important role in the research of the universe.The main purposes of quasar recog-nition are to identify the emission peaks in an observable quasar spectrum and to determine the observable quasars redshift value.Due to the inherent extremely noisy characteristics of quasar spectrums and the limitation of observable conditions,automatic quasar recognition is a hard problem to tackle,and the commonly used direct matching approaches based on rules are ineffective.This paper introduces a stratified approach based on Hough transform and neural network which is shown to be simple,efficient,robust and easy to generalize.
Quasar Objects (QSOs) are detectable at very large distance,with broad,red-shifted emission lines,strong ultraviolet and strong time variability of the optical light.QSOs play an important role in the research of the universe.The main purposes of quasar recog-nition are to identify the emission peaks in an observable quasar spectrum and to determine the observable quasars redshift value.Due to the inherent extremely noisy characteristics of quasar spectrums and the limitation of observable conditions,automatic quasar recognition is a hard problem to tackle,and the commonly used direct matching approaches based on rules are ineffective.This paper introduces a stratified approach based on Hough transform and neural network which is shown to be simple,efficient,robust and easy to generalize.
2000, 22(4): 536-542.
Abstract:
A fast algorithm is proposed for tracking low observable point-source targets of unknown position and velocity in a digital image sequence.It combines genetic algorithms and multistage hypothesis tracking method.The simulation results show that it can detect and track targets computational efficiently with SNR2.According to the difficulties of tracking point source targets with low SNR,coding and genetic operation are designed for this problem.Eligible points retaining as a new genetic operation is proposed here.
A fast algorithm is proposed for tracking low observable point-source targets of unknown position and velocity in a digital image sequence.It combines genetic algorithms and multistage hypothesis tracking method.The simulation results show that it can detect and track targets computational efficiently with SNR2.According to the difficulties of tracking point source targets with low SNR,coding and genetic operation are designed for this problem.Eligible points retaining as a new genetic operation is proposed here.
2000, 22(4): 543-548.
Abstract:
Spatial inspection and tracking are two important objects in the array signal processing field. A fast and robust tracking method for 2-D moving signals, which combines beamform and spectral peak searching is proposed. In the method, several spatial signals can be processed simultaneously. Furthermore, the effectiveness is demonstrated by computer simulation.
Spatial inspection and tracking are two important objects in the array signal processing field. A fast and robust tracking method for 2-D moving signals, which combines beamform and spectral peak searching is proposed. In the method, several spatial signals can be processed simultaneously. Furthermore, the effectiveness is demonstrated by computer simulation.
2000, 22(4): 549-554.
Abstract:
In recent years, estimation in cumulant domains was studied mainly in the aspect of asymptotic performance, including asymptotic unbiased estimation and asymptotic covariance. Unbiased estimation performance for finite snapshots is discussed in this paper. Simulation results demonstrate that performance of DOA unbiased estimation is better than that of biased for low SNR.
In recent years, estimation in cumulant domains was studied mainly in the aspect of asymptotic performance, including asymptotic unbiased estimation and asymptotic covariance. Unbiased estimation performance for finite snapshots is discussed in this paper. Simulation results demonstrate that performance of DOA unbiased estimation is better than that of biased for low SNR.
2000, 22(4): 555-559.
Abstract:
In this paper an excellent performance spectrum estimation algotithm based on wavelet transform is given. Because of the joint time-frequency localization characteristic of wavelet transform,this algotithm is also used in the spectrum estimation of short data series. The results of computer simulation illustrate that this method achieves high resolution, high accuracy, and low SNR threshold.
In this paper an excellent performance spectrum estimation algotithm based on wavelet transform is given. Because of the joint time-frequency localization characteristic of wavelet transform,this algotithm is also used in the spectrum estimation of short data series. The results of computer simulation illustrate that this method achieves high resolution, high accuracy, and low SNR threshold.
2000, 22(4): 560-567.
Abstract:
Study of congestion control for multipoint-to-point connections are still in early phases.So far the related works focus on extending point-to-point algorithms to multipoint-to-point environment,which can implement source-based fairness easily.But source-based fairness means no fairness between VCs at all.So VC/source based fairness may be the better choice.In this paper,issues about designing VC/source based congestion control algorithms are deeply studied.A set of design principles and a congestion control algorithm are proposed in the first time.Simulation results show that this algorithm can implement VC/source based fairness,converge fast to steady state,and have high link utilization.
Study of congestion control for multipoint-to-point connections are still in early phases.So far the related works focus on extending point-to-point algorithms to multipoint-to-point environment,which can implement source-based fairness easily.But source-based fairness means no fairness between VCs at all.So VC/source based fairness may be the better choice.In this paper,issues about designing VC/source based congestion control algorithms are deeply studied.A set of design principles and a congestion control algorithm are proposed in the first time.Simulation results show that this algorithm can implement VC/source based fairness,converge fast to steady state,and have high link utilization.
2000, 22(4): 568-572.
Abstract:
This paper proposes a nonlinear descision feedback interference suppressor (DFIS)used both in the estimation of filter reference input and the weight update to suppress multi-tone interference in CDMA.Structure of DFIS is simpler.Two kinds of estimation filter;I.e.,single-side prediction filter and two-side tapped filter are used.Expressions of the SNR improvement are derived.The results of simulation with comparison to the theoretical analysis for two estimation filters are presented on the rejection performance.
This paper proposes a nonlinear descision feedback interference suppressor (DFIS)used both in the estimation of filter reference input and the weight update to suppress multi-tone interference in CDMA.Structure of DFIS is simpler.Two kinds of estimation filter;I.e.,single-side prediction filter and two-side tapped filter are used.Expressions of the SNR improvement are derived.The results of simulation with comparison to the theoretical analysis for two estimation filters are presented on the rejection performance.
2000, 22(4): 573-578.
Abstract:
The problem of optimal coherent detection of M-ary frequency-shift keying (MFSK) signals transmitted over an additive colored Gaussian noise channel with imbalance gains in different frequencies (IGDF-ACGN channel) is studied. The structure of the optimal coherent detector is derived. Theoretical analysis and computer simulation results show that the detector is optimum in either additive colored Gaussian noise environment or additive white Gaussian noise environment.
The problem of optimal coherent detection of M-ary frequency-shift keying (MFSK) signals transmitted over an additive colored Gaussian noise channel with imbalance gains in different frequencies (IGDF-ACGN channel) is studied. The structure of the optimal coherent detector is derived. Theoretical analysis and computer simulation results show that the detector is optimum in either additive colored Gaussian noise environment or additive white Gaussian noise environment.
2000, 22(4): 579-584.
Abstract:
This paper points out some flaws in BAN-logic, and presents a modified version of the BAN-logic, which has a sound semantics and correct loigc rules. It is concluded that, if the initial condition is right, the result from this logic is right as well.
This paper points out some flaws in BAN-logic, and presents a modified version of the BAN-logic, which has a sound semantics and correct loigc rules. It is concluded that, if the initial condition is right, the result from this logic is right as well.
2000, 22(4): 585-590.
Abstract:
This paper studies a method using wavelet transform to estimate the signals spec-trum.The method is applied to the practical MMW radar targets echo signals,and on the condition of the same sampling frequency and sampling data length,it can achieve one dimen-sional range profile with profiles resolution superior to FFTs,so the one dimensional range profile of targets can be analyzed with high resolution,there is certain significance in the prac-tice.
This paper studies a method using wavelet transform to estimate the signals spec-trum.The method is applied to the practical MMW radar targets echo signals,and on the condition of the same sampling frequency and sampling data length,it can achieve one dimen-sional range profile with profiles resolution superior to FFTs,so the one dimensional range profile of targets can be analyzed with high resolution,there is certain significance in the prac-tice.
2000, 22(4): 591-596.
Abstract:
The effect of target motion on a synthetic range profile produced by a hopped-frequency radar is analyzed,and then a method for optimal estimation of motion parameter of targets is presented based on the least waveform entropy rule.Simulation results indicate that the method can accomplish accurate estimation of motion parameter of targets with a good anti-noise performance.
The effect of target motion on a synthetic range profile produced by a hopped-frequency radar is analyzed,and then a method for optimal estimation of motion parameter of targets is presented based on the least waveform entropy rule.Simulation results indicate that the method can accomplish accurate estimation of motion parameter of targets with a good anti-noise performance.
2000, 22(4): 597-606.
Abstract:
Principally the raw data of the space-borne synthetic aperture radar is two-dimensional Two-dimensional filters must be used to fulfill the transformation from the raw radar data to the focused image.A large memory space will be needed in the two-dimensional processing,and much computing time will be consumed.As a result,its implementation is very tedious in traditional computers.In this paper,the two-dimensional imaging processing is analyzed in detail based on parallel processing systems and the result shows that the processing time is short.
Principally the raw data of the space-borne synthetic aperture radar is two-dimensional Two-dimensional filters must be used to fulfill the transformation from the raw radar data to the focused image.A large memory space will be needed in the two-dimensional processing,and much computing time will be consumed.As a result,its implementation is very tedious in traditional computers.In this paper,the two-dimensional imaging processing is analyzed in detail based on parallel processing systems and the result shows that the processing time is short.
2000, 22(4): 607-612.
Abstract:
A new application of the ambiguity function is given in this paper to resolve the problem of moving targets imaging of SAR.It is well known that the SAR echo can be considered as a linear FM signal,so does the echo of moving targets.The square modulus of linear FM signal has high energy centrality in the ambiguity domain.Its peaks represent straight lines whose slopes equal to the Doppler rates of the moving targets echo signals.The parameters of moving targets can be estimated by applying the Radon transform to the ambiguity function.In this way,the moving targets can be easily detected and imaged.The simulation results prove the effectiveness and feasibility of this new method.
A new application of the ambiguity function is given in this paper to resolve the problem of moving targets imaging of SAR.It is well known that the SAR echo can be considered as a linear FM signal,so does the echo of moving targets.The square modulus of linear FM signal has high energy centrality in the ambiguity domain.Its peaks represent straight lines whose slopes equal to the Doppler rates of the moving targets echo signals.The parameters of moving targets can be estimated by applying the Radon transform to the ambiguity function.In this way,the moving targets can be easily detected and imaged.The simulation results prove the effectiveness and feasibility of this new method.
2000, 22(4): 613-617.
Abstract:
This paper discusses the characteristics displayed by long-and-thin conductive ob-jects in radar images.The results show that the objects may be displayed as strong signals if their axes are parallel with the incident electric field,otherwise they will be displayed as weak signals.
This paper discusses the characteristics displayed by long-and-thin conductive ob-jects in radar images.The results show that the objects may be displayed as strong signals if their axes are parallel with the incident electric field,otherwise they will be displayed as weak signals.
2000, 22(4): 618-625.
Abstract:
This paper proposes a new algorithm based on conformal mapping and FDTD method,and derives the numerical stability and numerical dispersion equations of conformal mapping FDTD algorithm.As an example,the relative errors of numerical wavelengths for TE modes in a circular waveguide in different cell number are calculated.The errors for different propagation constants and for different radius semicircle electric wall approaches to singularity at origin are analyzed.By selecting cell number appropriately,high accuracy can be obtained.
This paper proposes a new algorithm based on conformal mapping and FDTD method,and derives the numerical stability and numerical dispersion equations of conformal mapping FDTD algorithm.As an example,the relative errors of numerical wavelengths for TE modes in a circular waveguide in different cell number are calculated.The errors for different propagation constants and for different radius semicircle electric wall approaches to singularity at origin are analyzed.By selecting cell number appropriately,high accuracy can be obtained.
2000, 22(4): 626-631.
Abstract:
A new hybrid method based on the generalized network principle is proposed to deal with the electromagnetic scattering of a large body with cracks.Using the equivalence theorem,the total scattered field can be regarded as the summation of two parts,the scattering of the large body and that of the cracks.The former is calculated by using iterative physical optical (IPO) method directly and the latter can be computed as follows:First,the admittance matrix of the crack is extracted by using the FDTD method,thus the generalized network representation of the crack can be set up on the aperture.Then the equivalent magnetic current on the crack aperture can be computed by network principles.According to the reciprocity theorem,the scattering from the crack can be obtained finally.Some numerical results show the feasibility and efficiency of the proposed method.
A new hybrid method based on the generalized network principle is proposed to deal with the electromagnetic scattering of a large body with cracks.Using the equivalence theorem,the total scattered field can be regarded as the summation of two parts,the scattering of the large body and that of the cracks.The former is calculated by using iterative physical optical (IPO) method directly and the latter can be computed as follows:First,the admittance matrix of the crack is extracted by using the FDTD method,thus the generalized network representation of the crack can be set up on the aperture.Then the equivalent magnetic current on the crack aperture can be computed by network principles.According to the reciprocity theorem,the scattering from the crack can be obtained finally.Some numerical results show the feasibility and efficiency of the proposed method.
2000, 22(4): 632-638.
Abstract:
Suspended coplanar waveguides have the advantage of both finline and suspended stripline.In this paper suspended coplanar waveguides are analyzed using conformal mapping techniques,and the exact solutions are obtained.Analytic closed-form expressions for the effective dielectric constant,the capacitance per unit length and the characteristic impedance of the suspended coplanar waveguides with finite thickness of dielectric substrate are given.
Suspended coplanar waveguides have the advantage of both finline and suspended stripline.In this paper suspended coplanar waveguides are analyzed using conformal mapping techniques,and the exact solutions are obtained.Analytic closed-form expressions for the effective dielectric constant,the capacitance per unit length and the characteristic impedance of the suspended coplanar waveguides with finite thickness of dielectric substrate are given.
2000, 22(4): 639-644.
Abstract:
It is well known that the current distribution along the linear antenna is a key factor in the design of new type antennas.In this paper,a technique for numerical calculation of a dual-cylindrical antenna array is investigated.The admittance matrix of the equivalent network is also presented.A demonstrative calculation using this method is given and the numerical results obtained are good.
It is well known that the current distribution along the linear antenna is a key factor in the design of new type antennas.In this paper,a technique for numerical calculation of a dual-cylindrical antenna array is investigated.The admittance matrix of the equivalent network is also presented.A demonstrative calculation using this method is given and the numerical results obtained are good.
2000, 22(4): 645-652.
Abstract:
Based on multiresolution analysis,a method for computation of TE and TM modes in arbitrary cross sections is described.The method uses expansion in terms of scaling functions to approximate the axial field component (Ez or Hz) and transforms the field equation into a matrix equation by applying a variational formulation.The matrix elements are formulated by dividing the waveguide cross section into rectangles and using third-order B-spline.Numerical examples are provided for various waveguides to show the validity and effectiveness of the method.
Based on multiresolution analysis,a method for computation of TE and TM modes in arbitrary cross sections is described.The method uses expansion in terms of scaling functions to approximate the axial field component (Ez or Hz) and transforms the field equation into a matrix equation by applying a variational formulation.The matrix elements are formulated by dividing the waveguide cross section into rectangles and using third-order B-spline.Numerical examples are provided for various waveguides to show the validity and effectiveness of the method.
2000, 22(4): 653-658.
Abstract:
In this paper,a simple and fast method for calculating Reed-Muller expression is presented by using truth vector of multiple-valued function,and whether a function can be linearly or partially linearly decomposed can be determined.By using typical examples,syntheses of multiple-valued logic functions are shown.The method turns out to be effective.
In this paper,a simple and fast method for calculating Reed-Muller expression is presented by using truth vector of multiple-valued function,and whether a function can be linearly or partially linearly decomposed can be determined.By using typical examples,syntheses of multiple-valued logic functions are shown.The method turns out to be effective.
2000, 22(4): 659-666.
Abstract:
Available defect outline model used for yield prediction and inductive fault analysis of integrated circuits (IC) all model a real defect by replacing its real rugged outlines with circular discs or squares,then great errors were aroused in these models.Based on the idea of fractal interpolation,this paper presents a new model to characterize those real defect outlines.The comparison of the new model with those models available indicates that the new model is a more accurate defect outline model.
Available defect outline model used for yield prediction and inductive fault analysis of integrated circuits (IC) all model a real defect by replacing its real rugged outlines with circular discs or squares,then great errors were aroused in these models.Based on the idea of fractal interpolation,this paper presents a new model to characterize those real defect outlines.The comparison of the new model with those models available indicates that the new model is a more accurate defect outline model.
2000, 22(4): 667-671.
Abstract:
A biorthogonal wavelet transform (BWT) and fuzzy vector quantization (FVQ)based very low bit rate image coding algorithm is proposed.The correlation of the wavelet coefficients in different frequency bands is fully exploited through constructing the band-cross vector,so the high coding efficiency and reconstructed image quality are obtained simulta-neously.In addition,a hybrid vector quantization (VQ) scheme is presented to improve the performance of VQ,which combines the non-linear interpolated vector quantization (NLIVQ)technique with a novel progressive constructive fuzzy clustering algorithm.Simulation results demonstrate that the reconstruction quality is higher than 30dB at a very low bit rate of 0.172bpp.
A biorthogonal wavelet transform (BWT) and fuzzy vector quantization (FVQ)based very low bit rate image coding algorithm is proposed.The correlation of the wavelet coefficients in different frequency bands is fully exploited through constructing the band-cross vector,so the high coding efficiency and reconstructed image quality are obtained simulta-neously.In addition,a hybrid vector quantization (VQ) scheme is presented to improve the performance of VQ,which combines the non-linear interpolated vector quantization (NLIVQ)technique with a novel progressive constructive fuzzy clustering algorithm.Simulation results demonstrate that the reconstruction quality is higher than 30dB at a very low bit rate of 0.172bpp.
2000, 22(4): 672-676.
Abstract:
This paper presents a new algorithm that utilizes wavelet for color image coding.After wavelet decomposing and scalar quantization,Y,Cr,Cb components are coded separately using duplicate tree coding algorithm whicn can compress the high frequency subbands effectively.Experimental results show that the new algorithm is very practical and with good performance for color image coding.
This paper presents a new algorithm that utilizes wavelet for color image coding.After wavelet decomposing and scalar quantization,Y,Cr,Cb components are coded separately using duplicate tree coding algorithm whicn can compress the high frequency subbands effectively.Experimental results show that the new algorithm is very practical and with good performance for color image coding.
2000, 22(4): 677-681.
Abstract:
A new method of pilot-symbol-aided(PSA) channel fading estimation is proposed,which uses the data symbols and the pilot symbols to perform channel fading estimation and fading compensation,but normally only pilot symbols are used to estimate the signal distor-tion.The technique has the advantages of simple implementation and short delay time.The simulation based on 16PSK and 16QAM shows the performance of PSA-16QAM is better than that of PSA-16PSK,and the use of PSA technique can improve the performance relative to the differential detection.
A new method of pilot-symbol-aided(PSA) channel fading estimation is proposed,which uses the data symbols and the pilot symbols to perform channel fading estimation and fading compensation,but normally only pilot symbols are used to estimate the signal distor-tion.The technique has the advantages of simple implementation and short delay time.The simulation based on 16PSK and 16QAM shows the performance of PSA-16QAM is better than that of PSA-16PSK,and the use of PSA technique can improve the performance relative to the differential detection.
2000, 22(4): 682-686.
Abstract:
The capacity of the optical pulse-position modulation (PPM) channel without background noise is examined.It is shown that the channel capacity is limited not only by the available time resolution (bandwidth) but also by the available pulse power.In fact,as the PPM slot width decreases infinitely,the channel capacity will approach to zero in the power limited channel.There exist the PPM slot width that optimizes the channel capacity and the PPM alphabet sizes that maximize the efficiencies of throughput and energy.These results provide the basis for designing optimum PPM system parameters.
The capacity of the optical pulse-position modulation (PPM) channel without background noise is examined.It is shown that the channel capacity is limited not only by the available time resolution (bandwidth) but also by the available pulse power.In fact,as the PPM slot width decreases infinitely,the channel capacity will approach to zero in the power limited channel.There exist the PPM slot width that optimizes the channel capacity and the PPM alphabet sizes that maximize the efficiencies of throughput and energy.These results provide the basis for designing optimum PPM system parameters.
2000, 22(4): 687-691.
Abstract:
In this paper,the fire detection is divided into various rules related with the fire characteristic signals,the fuzzy theory and the neural networks are applied to get the rules.The new algorithm combining the fuzzy theory and the neural networks is deduced.The results are manifested:the fuzzy neural network is an effective technology for fire detection.
In this paper,the fire detection is divided into various rules related with the fire characteristic signals,the fuzzy theory and the neural networks are applied to get the rules.The new algorithm combining the fuzzy theory and the neural networks is deduced.The results are manifested:the fuzzy neural network is an effective technology for fire detection.
2000, 22(4): 692-696.
Abstract:
In the light of the target recognition based on MMW/IR fusion,a new neural network algorithm for the decision fusion is presented in this paper.The architecture of this network is novel.It is the thresholds,not the conjunction weights,that are modified,when the network is being trained.The mean correct recognition rate after fusion is higher than that of MMW and IR subsources by 9.7% and 11.3% respectively,which indicates this algorithm is effective and feasible.
In the light of the target recognition based on MMW/IR fusion,a new neural network algorithm for the decision fusion is presented in this paper.The architecture of this network is novel.It is the thresholds,not the conjunction weights,that are modified,when the network is being trained.The mean correct recognition rate after fusion is higher than that of MMW and IR subsources by 9.7% and 11.3% respectively,which indicates this algorithm is effective and feasible.
2000, 22(4): 697-699.
Abstract:
A novel encoder based on interpolation and prediction in multi-resolution levels is proposed,it can compress ocean geophysical exploration echoes and sound-logging data loss-lessly more than 50 per cent.
A novel encoder based on interpolation and prediction in multi-resolution levels is proposed,it can compress ocean geophysical exploration echoes and sound-logging data loss-lessly more than 50 per cent.
2000, 22(4): 700-704.
Abstract:
Based on the analysis of the directivity of the circular array,a symmetrical exponential weighting method which improves the directivity of the circular array is developed in this paper.Using this method,the sidelobe level can be efficiently rejected and the mainlobe width be little widened.
Based on the analysis of the directivity of the circular array,a symmetrical exponential weighting method which improves the directivity of the circular array is developed in this paper.Using this method,the sidelobe level can be efficiently rejected and the mainlobe width be little widened.
