最新刊期
卷 28 ， 期 9 ， 2000
- 摘要：Under the prerequisite that the statistics of both signal and noise are not known a priori,the Dopplerlet transform realized by using the adaptive pyramidal matching projection algorithm can perform effectively the denoising and interference cancellation.Moreover,the philosophy of signal restoration and the experimental results are provided.关键词：signal restoration;Dopplerlet transform;adaptive pyramidal matching projection algorithm2|1186|6更新时间：2025-07-16
- 摘要：We propose a QoS (quality of service) control mechanism which is end-to-end to improve quality of voice in IPhone system.This control system creates/maintains the flow states for time-sensitive voice streams to reserve the network resources and guarantees the statistical traffic characteristics through the virtual round robin algorithm during data transmission according to the result of admission control.This paper firstly describes the architecture of QoS control system,secondly gives the admission control algorithm and traffic control algorithm,finally discusses the effect of QoS control according the analysis of the test data.关键词：integrated service (Intserv);differential service (Diffserv);QoS;resource ReSerVation Protocol (RSVP)2|1143|0更新时间：2025-07-16
- 摘要：A method of embedding a color digital watermark into a gray-level image is proposed.By still image compression coding technique,the color digital watermark is encoded into a series of binary ID numbers for watermarking.The algorithm can extract the watermark without the original image because the embedding process is based on the relationship between the discrete cosine transform (DCT) coefficients of the original image.Experimental results show that the proposed technique is robust against some image processing operations and joint photographic experts group (JPEG) lossy compression.关键词：copyright protection;digital watermarking;discrete cosine transform2|2378|13更新时间：2025-07-16
- 摘要：It is pointed out that it is important to consider the case with active adversaries,as well as that with passive ones.Based on this knowledge,an improvement on Kailar logic is proposed for analysis of both fairness and accountability in electronic commerce protocols.关键词：electronic commerce protocol;accountability;fairness;formal analysis2|1192|8更新时间：2025-07-16
- 摘要：In this paper,the method of moments is used to compute sleeve monopole antennas.A new efficient and accurate modeling for moderately thick cylindrical wire antennas with a so-called 'equal length dividing method’ and a constant gap voltage source model is established to greatly improved the accuracy.By using the sinusoidal interpolate basis and Daubechies discrete wavelet transform,the computing time is considerably reduced.Finally,a practical sleeve antenna,with the VSWR less than 3.0 in 200~700MHz frequency band,is designed.The calculated results of these three antennas are all in good agreement with the experimental results.关键词：sleeve monopole antennas;method of moment;efficient and accurate modeling for moderately thick cylindrical wire antenna;sinusoidal interpolate basis;daubechies discrete wavelet transform2|1534|6更新时间：2025-07-16
- 摘要：This paper presents a novel adaptive method to predict the next point of target on-line by means of general wavelet neural network.The scaling function and wavelet constructed by the sigmoid function are used as the active function in the network.The number of hidden units is determined by the number of wavelet decomposition and the dimension of input signal.The local connection is used in the output layer to destroy the influence of multi-dimension signal processing.It is proved that the robust property of the wavelet network is better than that of BP network in certain conditions.Simulation shows that the computational cost of this method does not increase with the complexity of the model of moving target.Moreover,the method has the higher tracking accuracy for the moving targets with variable acceleration and quick turn in a corner.关键词：radar;tracking;wavelet neural networks2|778|0更新时间：2025-07-16
- 摘要：In ultra-wideband synthetic aperture radar (UWB-SAR),the radio frequency interference (RFI) suppression capacity can be greatly improved by putting an adaptive predictive error filter before the process of image formation.This paper proposes a fast and efficient method for RFI suppression,which gives the model order by spectral peaks and uses the Tank-Hopfield (TH) neural network to compute the coefficients of the filter.The method obtains higher computing efficiency with satisfactory results on interference suppression.关键词：ultra-wideband synthetic aperture radar (UWB-SAR);radio frequency interference (RFI);AR model;Tank-Hopfield (TH) neural network2|1100|4更新时间：2025-07-16
- 摘要：The clutter and noise correlation matrix estimated from system received data almost comprises the entire information about clutter and noise.An eigenvalue division(EVD) of the matrix can provide an eigenspace and within the space one can rank the power of the clutter and noise according to the metrics of eigenvalues whose eigenvectors are statistically independent and orthogonal to each other.Studies on adaptive processing especially on reduced-rank processing based on eigenspace can help probing the optimum approach in theory.The cross spectral method(CSM),minimum power eigencanceler(MPE) and minimum norm eigencanceler(MNE) are discussed respectively in this paper and the intrinsic relationship among them from the view of eigenstructure is revealed as well.Finally,the clutter suppression performance is compared by means of simulation.关键词：space time adaptive processing(STAP);cross spectral method(CSM);minimum power eigencanceler (MPE);minimum norm eigencanceler (MNE);clutter suppression2|1104|3更新时间：2025-07-16
- 摘要：In this paper,the P.O.method is used to predict the near field and far field of a monopulse ring-focus antenna with arbitrary polarization.By use of the Fourier series expansion,the radiation integral is simplified,respectively,from four dimensions to three dimensions for near field or two dimensions for far field.The formulae and codes developed have been tested by an experiment,and good agreement has been obtained.关键词：monopulse;circular ring-focus;near field distribution;pattern;polarization2|1159|1更新时间：2025-07-16
- 摘要：To detect a moving point target that is submerged in noisy background is a very difficult problem.A new approach to moving target detection based on multiscale geometric technique is proposed in this paper.A 4-D scale spatio-temporal space is constructed by multiscale approach using Gaussian as a filtering kernel.A motion constraint equation for moving target is derived by the first order geometric features.A technique for solving the problem of motion detection and velocity estimation based on the velocity identity and pixel connectivity of the target image is described.A coarse-fine search algorithm of the clustering point or area for constrainted straight lines on the velocity plane is outlined.An accuracy measure for precisely how to search an optimal scale of Gaussian is given.The experimant and comparison results are presented to support the research.关键词：noisy background;point target detection;multiscale approach;motion constraint equation;motion detection2|1229|1更新时间：2025-07-16
- 摘要：With information gain obtained by information entropy and evolution of information entropy which characterize uncertainty of target search location,an optimizing algorithm of detection and classification used in multisensors and multitargets is put forward.Namely,information entropy of current sampling time is computed and information entropy of next sampling time is predicted for each detection cell.The detection cell of maximum information gain is the next one to search.The effectiveness of algorithm is testified by simulation results.关键词：Information fusion;sensor management;information entropy;information gain2|1362|24更新时间：2025-07-16
- 摘要：The configuration of the amplifier for recording the ionic channel current of the cell is described here.The measured currents vary from 1 pA to nanoampers,and the output voltage is required to be processed by the computer.Therefore,the amplifier must be constructed in multistages.The key point for designing this amplifier is the low noise technique,especially for the headstage.The background noise of the main components and devices are particularly analyized with power density spectrum SI(f) and Sv(f) to characterize their characteristics.The test results of the designed patch clamp amplifier model PC-Ⅱ satisfy the practical requirement and the experimental data are given.关键词：patch clamp;current-voltage converter;background noise;low noise design2|1593|2更新时间：2025-07-16
- 摘要：By employing the Fourier-Bessel theorem to plane wave functions and through a series of deduction and inverse Fourier transform,one kind of series expansions of the product of Bessel functions and sine/cosine function in Cartesian coordinates is obtained.This expression can be used to compute the rectangular to circular waveguide junction and to analytically deduce its generatized S-parameters,which are in good agreement with results from other papers and HFSS.The coupling coefficient of rectangular iris with thickness are computed in Ku and Ka band,and numerical evaluations are presented,which show close agreement with experimental data and other paper.As a consequence,a 6th-order quasi-elliptic function filter in Ku band is realized through rigorous calculation of the coupling iris dimensions,and the measured data agree well with the predicted values.关键词：Bessel functions;series expansions;waveguide junction of rectangular to circular;coupling aperture (iris);rigorous calculation;quasi-elliptic function;filter2|1382|4更新时间：2025-07-16
- 摘要：Ray path tracing is a key step to apply geometrical theory of diffraction in solving the problems of high-frequency electromagnetic scattering and radiating.The paper introduces a dynamic programming method and gives the algorithm model for ray tracing on any convex surfaces.The algorithm model is tested by tracing the ray path on infinite cylinder.The method can be applied to trace the ray path on arbitrary convex surface with inhomogeneous media.关键词：ray path tracing;dynamic programming;geometrical theory of diffraction;discretization;convex surface2|1246|2更新时间：2025-07-16
- 摘要：Requiring a large number of arithmetic operations,the optimal video integrator for scanning radars is difficult to implement in real time.A new FIR video integrator,namely interpolated FIR video integrator,is proposed.Compared with the optimal integrator,the proposed integrator is computationally efficient and has reduced roundoff noise.Moreover,the new integrator has nearly the same performances as the optimal integrator.Therefore,the proposed integrator is practical.关键词：video integrator;SNR;interpolation;decimation2|910|0更新时间：2025-07-16
- 摘要：An improved maximum model distance approach was proposed to train HMM.By adopting a more realistic model distance definition,discriminative information contained in the training data could be used to improve the performance of recognizer.HMM parameter adjustment rules were induced.Both isolated word and continuous speech recognition experiments on TIMIT database showed that significant error reduction could be achieved by the improved approach.关键词：Hidden Markov Model (HMM);training approach;discriminative information2|979|1更新时间：2025-07-16
- 摘要：This paper first points out which is the main error affecting the performance of ultra wide band quadrature demodulation receiver.Then a method correcting the amplitude and phase errors of UWB quadrature demodulation receiver using complex coefficients digital FIR filters and an algorithm designing the complex coefficients FIR filters is presented,followed by a practical example.关键词：UWB;amplitude and phase correction;FIR filter2|1541|6更新时间：2025-07-16
- 摘要：Jointly tracking the time-varying parameters of array incident signals is the chief problem that our troops efficiently carry out electronic defense and offense in modern electronic war(EW).Aiming at the problem that the methods to estimate time-invariant parameters don't adapt themselves to the situation to track time-varying parameters,this paper has probed into the method to jointly track time-varying parameters of array signals based on the plane rotation(Givens rotation).The computer simulation results proved the effectivity of proposed method.关键词：array signal;subspace update;plane rotation;jointly tracking parameters2|856|0更新时间：2025-07-16
- 摘要：A novel DOA estimation algorithm based on the largest eigenvalue of the covariance matrix is presented.It mainly applies to the pencil beam smart antenna in DS-CDMA systems.Different from other DOA estimation algorithms,it only picks up the main path signal of the target user.Thus it can get a high resolution with lower computational requirements.Theoretical analyses and simulation results show that this method has quite good stability and robustness,especially under severe multipath propagation circumstances.关键词：smart antenna;code division multiple access;direction of arrival estimation2|1173|2更新时间：2025-07-16
- 摘要：A new cumulate extrema-based algorithm,for blind deconvolution of the sandwich nonlinear system,is developed.By introducing the intermediate variable as hidden variable,the learning of deconvloution system is fulfilled with an iteration learning process of two parts.The first part is a conventional learning of the post nonlinear system (PNS) with complete training sets,and the second part is in fact equivalent to blind deconvolution of a linear system.Compared with the other algorithm,the new algorithm has a faster convergence speed.关键词：blind deconvolution of nonlinear system;cumulants extrema;hidden variables2|1099|1更新时间：2025-07-16
- 摘要：Multisensor data fusion has played an important role in image processing recently.Traditional image processing is a typical two-dimensional signal processing.The image data fusion belongs to this area as well.For some images from the same scene with different kinds of noise,this paper presents a new kind of image data fusion algorithm based on the one-dimensional self-organizing feature map neural network.This method uses equal gray density figure to determine the number of clusters,and utilizes one-dimensional pixel value to perform two-dimensional image processing.Simulation results demonstrate the effectiveness of the proposed image data fusion method.关键词：image filter;one-dimensional self-organizing feature map neural network;image data fusion6|1250|3更新时间：2025-07-16
- 摘要：Thick diamond films were synthesized on Al2O3 rod using a microwave plasma chemical vapor deposition technique,which can be taken over the traditional BeO rod and used in the wide-band high power TWT to improve the heat dissipation greatly.After material tests and evaluation,parts assembly and tests,we've got the first good results as follows:Thermal conductivity:＞12 W/cm.℃,ten times better than BeO Rod;dielectric constant:ε=5.0~5.5;RF loss:tanδ＜1×10 -3;resistivity:ρ＞10１3Ω/cm;slow wave parts assembly thermal test:3.0 times better than BeO.The first TWT with diamond rods has passed all cold tests and has got following hot test results:Δf=4~8GHz,Pout=95W,G=35db.关键词：microwave plasma;CVD;support rod;diamond;TWT;heat dissipation2|987|2更新时间：2025-07-16
- 摘要：The discrete cosine transform (DCT) is an important mathematical tool in digital image processing and many other fields.In this paper,a new Fourier analysis technique called the arithmetic Fourier transform (AFT) is used to compute DCT.The AFT of even functions is improved in this paper.The improved AFT reduces the samples needed to a half,consequently reduces the additions needed to a half.More importantly,it builds up a direct relationship between AFT and DCT.The algorithm for computing DCT using improved AFT is then deduced.This algorithm has many good performances such as it needs few multiplications (O(N)),it has a unified formula and a simple structure,it can be easily performed in parallel and it is especially suitable for VLSI designing.The algorithm creates a new approach to the fast computation of DCT.关键词：discrete cosine transform(DCT);arithmetic Fourier transform(AFT);discrete Fourier transform(DFT)2|1730|6更新时间：2025-07-16
- 摘要：Genetic algorithms (GAs) are successfully applied to the optimization of microstrip antenna design.This paper discusses some basic problems in this application thoroughly,such as the definition of genetic series,the combination of GAs and method of moment,the design of fitness function and the selection of control parameters.Using GAs,a wide band microstrip antenna is designed,the bandwidth expands from 5% to 16.6%.A dual frequency antenna is also optimized.The ratio of these two frequencies is 1∶1.31 and both frequencies have the same linear polarization.关键词：genetic algorithms;microstrip antennas;moment of method;broadband antenna;dual frequency antenna2|1608|8更新时间：2025-07-16
- 摘要：A 2GHz circularly polarized copper microstrip antenna and a 4.5GHz circularly polarized YBCO microstrip antenna are designed and fabricated.The copper microstrip antenna has a beam-width of 63° and an axial ratio of 1.2dB.The superconducting YBCO antenna has about 3dB gain improvement over the comparable silver antenna at 77K.The beam-width of the superconducting antenna will be larger than 63°,which will make circularly polarized YBCO microstrip antenna more praticable in some space communication fields.关键词：circularly polarization;microstrip antenna;HTS(high temperature superconductor)2|942|0更新时间：2025-07-16
- 摘要：In this paper,it is presented how to use FDTD to analyze the electromagnetic characteristic of the planar periodic structures. The FDTD combined with periodic boundary condition (PBC) and absorber boundary condition (ABC) becomes the accurate and efficient tool for various periodic structures. In order to develop a wide band PBC and correct iteration in time domain , a set of auxiliary elements are introduced and some modification are performed. Finally some examples based on a doubly periodic infinite planar frequency selected surface (FFS) are presented.关键词：periodic structure;periodic boundary condition;FDTD method2|1264|1更新时间：2025-07-16
- 摘要：Extending the two most basic independent integral equations of field theory in sinusoidal steady state to the non-sinusoidal cyclic steady state and the most basic law of circuit theory in non-sinusoidal cyclic state was deduced.关键词：non-sinusoidal cyclic steady state;two most basic independent integral equations;basic laws of circuit2|864|1更新时间：2025-07-16
- 摘要：In this paper,the intrinsic qualities of invariant terms in 3D MLFMA are discussed at first.They are αmlm'l's invariance of translation,the central conjugate symmetry of Vs or Vf on space,and the symmetric sparse matrix sparse and equivalency between Vs and Vf while using Galerking method.Using these factors,we can optimize the invatriant terms' calculation in MLFMA program.As a result,the complexity of calculating αmlm'l is reduced from O(Ml(63-33)) to O(73-33) and even to O((73-33)/8),Vs and Vf are reduced from O(KLN) to O(KLN/4),and Aji from O(N) to O(N/2).Numerical results show the validity of optimizing.关键词：MLFMA;translation-invariance;computing complexity2|1266|18更新时间：2025-07-16
- 摘要：Codebook design algorithms based on tabu search (TS) approach are presented for vector quantization (VQ).The key questions of the tabu search are how to define a solution and how to generate neighboring solutions of the current solution.The two optimality criteria of codebook design are nearest neighbor condition and centroid condition,so two corresponding methods to generate new solutions that are called codebook-based tabu search (CB-TS) algorithm and partitioning-based tabu search (PB-TS) algorithm are presented respectively.In order to improve the performance of the tabu search algorithm,simulated annealing technique is introduced.In order to improve the codebook performance,the conventional LBG algorithm is introduced in each iteration of the tabu search algorithm.Tests show that the proposed two algorithms based on the tabu search approach can greatly improve the codebook performance compared to the conventional LBG algorithm.关键词：vector quantization;codebook design;tabu search;simulated annealing2|1097|7更新时间：2025-07-16
- 摘要：SPIHT algorithm yields some of the best compression performance levels as reported in the literature.However,because the location information is alsways interleaved with the quantization information in the output bit stream,SPIHT tends to be highly sensitive to channel noise.In this paper,we propose a new source-channel coding method based on the original SPIHT.It makes use of embedded code stream instead of changing it.The channel coding can be fulfilled at the same time while doing source coding.The method greatly enhances the resilience to channel errors,which is important for using SPIHT in practice especially in wireless applications.关键词：image compression;hybrid coding;noisy channel environments;coding bit rate;PSNR2|972|1更新时间：2025-07-16
- 摘要：A method of suppressing HF sky-wave interference in ground wave OTH radar is put forward,in which three dimension orthogonally polarized receiving antennas are utilized.The new technique can suppress the sky-wave interference which can't be handled in a two dimension orthogonal polarization filter.In order to further improve the interference suppression ability,an optimum weighting method is given.It is proved in theory that the weighting method can effectively decrease polarization loss,increase output SINR and enlarge interference suppression area in polarization domain and space domain.关键词：polarization filter;interference suppression;OTH radar;polarization loss2|1256|9更新时间：2025-07-16
- 摘要：This paper set up a clutter model for airborne early warning radar(AEW radar)with stochastic integral.By this model we realize that when array antenna is broadside,clutter process is a low-pass stationary process,and a snapshot obtained from array antenna is a sampled sequence of it.Under the hypothesis that clutter is Gaussian,we obtain the correlation function and power spectrum of clutter process.At the end of the paper,the model is verified by using the Mountain Top data.关键词：STAP;airborne early warning radar;clutter4|1071|3更新时间：2025-07-16
- 摘要：In this paper,an adaptive learning procedure for constructing and training radial basis function networks is proposed,based on the adaptive projective algorithm.The procedure chooses the centers of radial basis function and the weights of networks one by one until an adequate network has been constructed,providing a simple and efficient means for growing radial basis function networks.This is illustrated by two examples on communication channel equalizer and the prediction of a time series.关键词：radial basis function networks;adaptive projective algorithm;network structure;channel equalization;time series prediction2|952|3更新时间：2025-07-16
- 摘要：In this paper,STAP(space time adaptive processing) for an airborne fire-control radar to detect slowly moving ground targets is discussed.The system of this kind is characterized by its forward looking antenna,short wavelength,high flight velocity and low PRF,which results in the highly ambiguous Doppler frequency of ground clutter and large Doppler bandwidth of mainbeam clutter.Conventional processing can not give good performance of detection.This paper is focused on the features of detection of slowly moving ground targets by use of the airborne fire-control radar,and the cascade processing and joint processing are compared.Finally,simulation results are included to validate the conclusions.关键词：GMTI(ground moving target indication);STAP(Space Time Adaptive Processing);clutter suppression3|1071|3更新时间：2025-07-16
- 摘要：The narrow pulse produced by the race-hazard of clock is used to control the ternary latch,so as to meet the 'non-transparent’ demand.Based on it,a CMOS D-type ternary edge-triggered flip-flop is proposed.This design is proved to have an exact logic function by PSPICE simulation,and it has a simple construction and lower power dissipation at the same time.关键词：multi-valued logic;latch;flip-flop;race-hazard;low power dissipation2|1364|5更新时间：2025-07-16
- 摘要：In this paper,a normalized two-dimensional band-limited Weierstrass fractal function is presented for modeling the rough surface,and an analytic solution of the scattering field from two-dimensional band-limited Weierstrass fractal surface is derived based on Kirchhoff theory.The scattering field,the average scattering coefficient and the variance of scattering intensity are given to study the influence of fractal dimension and other related parameters on the scattering field by theoretical analysis and numerical calculations.关键词：fractal rough surface;Kirchhoff approximation;electromagnetic scattering2|1346|10更新时间：2025-07-16
- 摘要：This paper describes the authorization-controlled cooperative cache mechanism used in the NOW-based parallel file system PARFSNOW++.To solve the problems of current cooperative cache mechanisms,the paper presents a new cache coherence technique and a new data replacement technique.These new techniques can be used to improve the efficiency of the cooperative cache system.Through some test results,this paper also demonstrates that these new techniques indeed improve the performance of PARFSNOW++.关键词：NOW;PFS;cooperative cache;MCS2|941|0更新时间：2025-07-16
- 摘要：This paper presents a new systolic ASIC scheme to implement the undistorted parallel data compression algorithm based on genetic algorithm (GA).In comparison with other traditional sequential or small-scale parallel methods of data compression,the proposed systolic scheme has much higher parallelism,real-time performance and more suitability.The simulation of timing performance and functionality for the ASIC scheme verifies its correctness and effectiveness.3|1397|0更新时间：2025-07-16
- 摘要：In this paper,fast decoding algorithms for convolutional codes,which are based on the genetic algorithm (GA),are presented.They search from one side or both sides of the trellis respectively to implement unidirectional decoding (U-GA) or bi-directional decoding (B-GA).With good diversity,wide search region and global optimal ability of GA,the decoding performance can be improved.The effects of U- and B-GA and population size M on Pb are analyzed.Simulation results show that,with the same decoding computation efforts and at Pb=10-6,B-GA achieves about 0.5 dB coding gains over M- algorithm (MA) for the coding constraint length K=19 code,and 1dB gain over Viterbi algorithm (VA) with the K=7 code.关键词：convolutional code;decoding algorithm;genetic algorithm;performance2|1048|4更新时间：2025-07-16
- 摘要：The dispersion equation of corrugated waveguide filled with plasma under small signal condition is obtained with the ion channel and the beam pulsation taken into account in this paper.The dispersion properties are discussed in detail.The relation between the wave growth rate and plasma density is studied.Because of its consideration on the changes of the system after the beam injection,this method should be more reasonable.关键词：corrugated waveguide;dispersion;linear theory;electron beam;plasma2|1046|0更新时间：2025-07-16
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