最新刊期
卷 36 ， 期 3 ， 2008
- 摘要：This paper presents clutter space-time modeling method of bistatic space based radr(B-SBR).We analyze the bistatic geometry and obtain the analytic resolutions of clutter isorange contours.New Doppler frequency induced by earth’s rotation is considered.Finally,clutter angle-doppler traces for some scenarios are plotted and discusses based on the model.The clutter model can be used to analyze clutter space-time characteristics for different bistatic configurations,and develop clutter suppression methods.关键词：bistatic space based radar(B-SBR);earth rotation;clutter0|2|9更新时间：2025-07-02
- 摘要：Compared with the monostatic synthetic aperture radar(SAR)case,the situation in the bistatic SAR case is more complex.First,the geometry of the bistatic SAR is more complex.Second,both the deviations of the transmitter and the deviations of the receiver will introduce motion errors.These lead to an increased complexity for motion compensation of the bistatic data.This paper presents a method for estimating and compensating the motion errors of the bistatic data.Based on the motion error model of the bistatic SAR,an analytic expression that shows the variation of the motion error in the line of sight(LOS)direction with range is derived.Then,the estimated doppler rate and the image contrast are used to calculate the motion parameters.Finally,the motion compensation are implemented separately in the LOS direction and in the along track direction.By using this method,the three dimentional motion errors of the transmitter and receiver can be compensated effectively,and furthermore,the requirement for the inerial navigation system can be decreased.Results on the simulated data and the real data are provided to show the effectiveness of this method.关键词：bistatic synthetic aperture radar;motion compensation;motion error extraction;radar imaging0|2|2更新时间：2025-07-02
- 摘要：Ocean retracking is an important step for the 1B data processing of ocean radar altimeter.We can obtain precise estimates of ocean parameters by ocean retracking.It is important to use point target response(PTR)and weight window to correct these estimates.This paper proposes a new approach to perform ocean retracking for radar altimeter with PTR and weight window,which are used to reconstruct the waveform model of ocean retracking.We processed the data of SZ-4 radar altimeter with the new approach and compared with those of ERS-2 and buoys in the same period.The results show that our approach is effective for improving the accuracy of the estimates.关键词：radar altimeter;retracking;parameter estimating;point target response;weight window0|2|1更新时间：2025-07-02
- 摘要：The conventional methods for aircraft targets imaging often require that the correlation of the radar returns is high enough,thus,the SNR level of the radar returns should be high enough.However,due to the existence of the sea clutter and the noise,the SNR level of the radar returns may be low.In this paper,a novel method is proposed for airborne radar imaging of ship targets at the low SNR level.To eliminate the second order coupling between the range frequency and the slow time,the slow time scaling transformation is first applied on the raw data.Then,based on the minimum entropy criterion,the slope of the envelope is searched,leading to an accurate correction of the residual range walk.And then,the fractional Fourier transformation is used to estimate the parameters of the scatters.After that,the instantaneous image of the ship targets is obtained.The analysis and the imaging results of real data show that,for the processing of the data with a low SNR,the performance of the proposed method is better than that of the conventional one.关键词：synthetic aperture radar;low SNR;radar imaging;parameter estimation;fractional Fourier transformation0|2|0更新时间：2025-07-02
- 摘要：In order to improve the robustness against the array steering vector mismatch,the norm constraint on the weight vector is used.By the complete investigation on the norm inequality constraint Capon beamformer(NICCB),the existence of its solution is analyzed in detail,the choice of the norm inequality constraint parameter for NICCB is analyzed and the selecting bound is given.Since the norm equality constraint is stronger than the norm inequality constraint,the robustness of the norm equality constraint Capon beamformer(NECCB)is more excellent than NICCB,and the NECCB is proposed and solved efficiently.Numerical examples attest the correctness of the theory,and show that when the norm constraint parameter is selected in the allowable bound,the performances of the optimal NICCB and NECCB vary unobvious respectively,but NECCB has the better performance than NICCB.关键词：Capon beamformer;steering vector mismatch;norm constraint;diagonal loading;negative loading0|2|7更新时间：2025-07-02
- 摘要：The rational function approximation technique (RFAT) is applied to the hybrid finite-element/boundary-integral/multilevel fast multipole algorithm (FE/BI/MLFMA) to acquire wide-band and wide-angle backscatter radar-cross-section (RCS) by complex targets in this paper.The two approaches of utilizing the rational function approximation technique,asymptotic waveform evaluation (AWE) and model-based parameter estimation (MBPE),both have been investigated and compared by theoretical analysis and numerical experiments.The numerical results acquired by the developed computing algorithm of integrating the hybrid FE/BI/MLFMA with the RFAT are presented in the paper,demonstrating that the rational function approximation technique can greatly speed up the hybrid FE/BI/MLFMA to acquire wide-band and wide-angle backscatter radar-cross-section (RCS) by complex targets.0|2|1更新时间：2025-07-02
- 摘要：The segmentation of synthetic aperture radar (SAR) images is greatly complicated due to the presence of speckle.A SAR image segmentation method robust to speckle is proposed in this paper.Spatial information,containing the edge information and the relative location and intensity information of neighboring pixels across scales,is incorporated into the similarity measure of fuzzy c-means (FCM) algorithm,which enhances the robustness of the method to speckle.The FCM algorithm is spatially adjusted by the particle swarm optimization (PSO) algorithm to obtain appropriate adjustment parameters that can provide better segmentation results.The proposed method is not sensitive to initial segmentation result and is robust to speckle.Experimental results on the MSTAR dataset demonstrate that the proposed method is capable of effectively segmenting SAR images and achieving better results than the improved FCM (IFCM) algorithm.关键词：synthetic aperture radar (SAR) image segmentation;multi-scale analysis;fuzzy c-means (FCM) clustering;particle swarm optimization (PSO) algorithm0|2|10更新时间：2025-07-02
- 摘要：For estimating spectrum with high resolution based on the singular sample covariance matrix,a spectral estimator without diagonally loading is proposed with dynamic constraint.On the one hand,according to the structure of the singular sample covariance matrix,the proposed method adjusts the constraint of the error of the steering vector projection on its range subspace,and then the narrow filter with low noise gain is obtained.On the other hand,the method utilizes the correlation among the snapshots to form the Capon weight.The designed narrow filter,which is centered on the frequency of interest,and the corresponding Capon weight are applied on the data matrix to obtain the amplitude estimate at the frequency.Simulation and experimental results show that:in case of sample covariance matrix singular,the proposed spectral estimator has better estimation accuracy and resolution than the other estimators,which employ the singular sample covariance matrix for estimating spectrum,the estimated spectrum also efficiently maintains the raw structure of spectrum.Therefore,the proposed estimator is an efficient spectral estimation method with utilizing the singular covariance matrix.关键词：radar data processing;spectral estimation;matched filter0|2|2更新时间：2025-07-02
- 摘要：A high accuracy estimation algorithm of joint direction-of-arrival (DOA) and polarization for broadband signals is presented in this paper.The L-shaped sparse uniform crossed-dipoles are exploited in proposed method,whose element spacing is larger than wavelength of input signals carrier.The ESPRIT method is employed to estimate the ambiguous spatial phase.In order to resolve the conflict between array aperture and angle ambiguity,the direction information involved in the crossed-dipoles is used to implement disambiguation.This approach can improve the precision of estimation without element loss.Through computer simulations,the estimate performance versus signal-noise-ratio (SNR),the ability of extended array aperture and estimate performance under the condition of signals carrier wave with 2-18GHz frequency range are analyzed.关键词：array signal processing;broadband;DOA;polarization;sparse array0|2|2更新时间：2025-07-02
- 摘要：Aiming at the turntable-arc-orbit measurements method,a super-resolution algorithm for the 3-D scattering centers extraction is presented based on the 2D MEMP method.The method estimates the signal parameters correctly by utilizing the structure of a Hankel matrix and the space invariance technology,and needs no additional pairing step.The numerical simulations of a cube model with 8 scattering centers in its vertex indicate that the method estimates the parameters correctly and is much robust to noise.The method is further extended to the N-dimensional case and a general expression for estimation is given.关键词：radar;scattering centers extraction;super-resolution;singular value decomposition(SVD)0|2|3更新时间：2025-07-02
- 摘要：Due to the complexity of the nonlinear moment approximation equations,a higher order sigma points design algorithm based on the characteristics of the probability density function is proposed.The correspondence of the extremum of higher order derivatives of the Gaussian density function and the location of the sigma points are exploited.Thus the extremum of higher order derivatives of the Gaussian density function are selected to be the location of the sigma points that can improve the estimation precision.It is corroborated in the theoretical analysis and the simulation that the proposed algorithm can easily derive higher order unscented filters with high efficiency.关键词：nonlinear;unscented transformation;moment approximation;sigma points0|2|1更新时间：2025-07-02
- 摘要：Nix-Vector routing mechanism is improved and MTree-Nix routing is presented.MTree-Nix maintains variable number of spanning trees as the base routing table,and uses Nix-Vector routing to compute on demand the routing states that cannot be covered by any of the spanning trees.Through analyzing space and time complexity,we obtain the constraint condition of the optimized trade-off between space and time requirement in MTree-Nix.Experimental results show that MTree-Nix can reduce the simulation time for about 85%.关键词：network simulation;routing mechanism;Nix-Vector;spanning tree0|2|6更新时间：2025-07-02
- 摘要：Based on the definition of wavelet spectrum of the maximal overlap discrete wavelet transform,we propose a novel algorithm for determining the local singularity exponents,which provides the local scaling information of interest,and construct a singularity-spectrum-like histogram to describe the global statistical distribution of the local singularity strengths.The validity and efficiency are verified by numerical experiment and application to real heart rate data.关键词：singularity spectrum;local hlder exponents;wavelet transform0|2|0更新时间：2025-07-02
- 摘要：By utilizing the frequency-response-masking (FRM) technique,a novel approach for the design of efficient sharp finite-impulse-response (FIR) digital filters was presented based on a neural-networks optimal design algorithm.The main idea is to minimize the squared-error function in the frequency-domain to obtain FRM filter coefficients.Algorithmic details for the design of basic and multistage FRM filters were presented,the stability theorem was also proved to illustrate the validity of the proposed algorithm,and the implementation of the approach was described together with some design guidelines.Some simulations were included and the results show that the proposed algorithm can design better FRM filters than conventional methods.关键词：frequency-response-masking;FIR digital filter;optimal design;stability theorem0|2|1更新时间：2025-07-02
- 摘要：A multi-resolution fusion method to enhance a multispectral image by merging with a high spatial resolution image is developed,which introduces the correlative restriction into the statistical mode.Using the method,the interrelated spatial information is well enhanced,and the spectral information of multi-spectral images is effectively kept.The validity of the method is proved by experiment for real remote sensing images.关键词：multispectral images;image fusion;multi-resolution analysis0|2|3更新时间：2025-07-02
- 摘要：One of the most challenging research issues in content-based image retrieval (CBIR) is how to bridge the significant semantic gap between the low-level image features and the high-level semantic concepts.The well-known solutions are relevance feedback and regions of interest (ROIs) detection;however both are subjective and time-consuming.We propose the visual information is a new feature that can objectively interpret the high-level concepts and effectively reduce the semantic gap in image retrieval.We also make a survey on the research progresses and key technologies of visual perception.The research issues of image retrieval based on visual perception are introduced as well from four aspects:ROIs detection,image segmentation,relevance feedback and personalized retrieval.关键词：visual perception;image retrieval;semantic gap;region of interest;relevance feedback0|2|19更新时间：2025-07-02
- 摘要：Among the various particle filtering (PF) evolutions,the bootstrap PF (BPF) is the most classical and popular algorithm.However,it is subject to severe sample impoverishment after resampling.To overcome the above problem,the fission BPF (FBPF) algorithm is proposed,in which the preprocess including weights sorting,particle reproducing by fission,and weights normalizing is inserted before the original resampling step as soon as the importance weights degenerate severely.The results of Monte Carlo simulations about a typical severely nonlinear filtering problem with bimodal posterior density have demonstrated that compared to the BPF,the more robust FBPF can escape successfully from the sample impoverishment problem as well as preserve the estimation accuracy and computation burden.关键词：recursive nonlinear filtering;extended kalman filtering;particle filtering;bootstrap particle filtering;reproduction by fission;fission bootstrap particle filtering0|2|33更新时间：2025-07-02
- 摘要：Side peaks of digital video broadcasting-terrestrial (DVB-T) signal ambiguity function may cause false alarms in DVB-T based passive radar.Based on deducing the side peak positions and analyzing the causes of the side peaks,a method for suppressing the side peaks is proposed in this paper.Experimental results show that the proposed method can avoid false alarms of the side peaks and increase the target detection ability.关键词：digital video broadcasting-terrestrial signal;passive radar;ambiguity function;side peaks suppression0|2|17更新时间：2025-07-02
- 摘要：This paper proposes a new beamforming approach,against arbitrary algebraically-tailed impulsive noise of otherwise unknown statistics. (This includes all symmetric alpha stable noises). This new beamformer minimizes the "geometric power" error between the beamformer’s output and the reference signal. This "geometric power" error is defined in terms of the logarithmic moment. The iteratively re-weighted least squares (IRLS) algorithm is adopted to calculate the proposed beamformer weights. Relative to costmary fractional lower order errors based beamformer,the proposed beamformer offers advantages such as: simpler computationally;needing no prior information nor estimation of the numerical value of the impulsive noise’s effective characteristic exponent,applicable to a wider class of impulsive noises;and improving the performance in terms of lower estimation errors. Computer simulation results verify the efficacy of the proposed beamformer.关键词：impulsive noise;beamforming;geometric power;logarithmic moment;symmetric alpha stable distribution0|2|6更新时间：2025-07-02
- 摘要：The near orthogonal hierarchical vector basis functions are used for solving three-dimensional time-domain electromagnetic integral equations (TDIE) of the metallic object.This basis functions are defined on the bilinear quadrilateral,and not require the patches conform which will make the geometry modeling easy.Those bases are implemented with Galerkin’s method in space and point match in time domain for the solution of TDIE,and the implicit matching on time method is used in this paper.Simulation results are given to show the high accuracy,efficiency and stability of this method.关键词：higher order method;higher order hierarchical vector basis functions;time-domain electromagnetic integral equations0|2|5更新时间：2025-07-02
- 摘要：A fast parallel algorithm via vector finite element method/multilevel fast multipole algorithm (vector-FEM/MLFMA) is introduced. In this algorithm the calculation of vector-FEM part can be finished at elementary level and no need to form the global coefficient matrix,so the CPU time and memory can be reduced significantly. For the MLFMA part,by expanding the basis functions and testing functions with Dirac functions on different position,the integration calculation of impedance can be simplified and all the transformation procedure can be calculated by fast Fourier transformation (FFT). Some other improved measure about MLFMA is introduced simultaneously. The numerical results show the effectiveness of the presented parallel algorithm.关键词：vector finite element method;multilevel fast multipole;electromagnetic scattering;parallel algorithm0|2|0更新时间：2025-07-02
- 摘要：An algorithm for image enhancement based on the nonsubsampled contourlet transform and adaptive threshold is proposed.The coefficients in different scales and different directions are obtained by image decomposition using the nonsubsampled contourlet transform.With these coefficients,thresholds and the enhancement functions are adaptively set.After the enhancement and then reconstruction of these coefficients,image enhancement is implemented.Compared with other algorithms,this algorithm can get better effect.关键词：nonsubsampled contourlet transform;adaptive threshold;image enhancement0|2|24更新时间：2025-07-02
- 摘要：An unsupervised classification method is proposed for fully polarimetric SAR data.The total backscattering power SPAN combined with the entropy H,the α angle and the anisotropy A is used to initialize the polarimetric SAR data.An agglomerative hierarchical clustering algorithm is introduced to reduce the number of clusters.The experimental results show that the SPAN has the additional information that is not contained in the H/ α /A,and this information is important for the initialization.It is also shown that the proposed classification algorithm provides better performance than the general Wishart H/ α /A classification.关键词：Cloude-Pottier decomposition;agglomerative hierarchical clustering;unsupervised classification;polarimetric SAR0|2|12更新时间：2025-07-02
- 摘要：As a new sparse signal representation algorithm,SBL (sparse Bayesian learning) method has no structural error as BP and has much fewer local minima than FOCUSS.ISAR imaging problem can be transformed into a sparse signal representation problem,therefore in the paper SBL is first applied in ISAR imaging.Imaging results of real data show SBL is a more effective ISAR imaging algorithm than BP and FOCUSS.关键词：ISAR(inverse synthetic aperture radar);sparse signal representation;SBL(sparse Bayesian learning);BP(Basis Pursuit);Focal underdetermined system solver1|2|6更新时间：2025-07-02
- 摘要：A method for calibrating the gain,phase and location of the transmit array based on FFT is presented,where the features of bistatic Sythetic Impulse and Aperture Radar (SIAR),the received direct wave and the receiver direction measured by Global Position System (GPS) are employed.One receiver direction is necessary for the gain and phase calibration,while three directions are needed for the gain,phase and location calibration.A discussion is made of the requirement for the three directions and the calibration in the presence of moving receiver and multi-path.The effect of GPS measurement uncertainty is analyzed.The computer simulation shows that the performance of the calibration method is high.The method can also be easily implemented owing to its small amount of computation and no need for accurate auxiliary antenna or auxiliary sources.关键词：bistatic;sythetic impulse and aperture radar(SIAR);transmit array calibration;direct wave0|2|1更新时间：2025-07-02
- 摘要：At present,the low modeling efficiency is a prevalent problem in particle-in-cell (PIC) simulation softwares.The CAD technology was introduced into the design of PIC simulation software to solve this problem.Considering the various complex physical models and numerical conditions in PIC simulation,the whole CAD system was divided into six functional modules and three system layers with object-oriented method.The six functional modules contained basic setting,algorithm setting,structure modeling,probe setting,simulation control and data process.The system layers were user interface layer,data managing layer and computing interface layer.Each of the modules and layers was well analyzed and designed.Finally,after integrating the CAD system and the kernel calculation code,a more practical PIC simulation software was formed and applied to design of high power microwave devices.The results show that the CAD system has very high practicability.关键词：PIC(particle-in-cell)simulation;CAD(computer aided design)technology;object-oriented method0|2|1更新时间：2025-07-02
- 摘要：Improved electric field integral equation(IEFIE) for solving electromagnetic scattering from arbitrary irregular targets is studied in this paper.By extracting the principle value term from the magnetic field integral equation(MFIE),and then adding it to both sides of the conventional electric field integral equation(EFIE),a iterative IEFIE can be obtained.Double iteration processes are needed instead of conventional iteration.It can work well because the current will be continuously updated in the outer iteration process.The IEFIE drastically reduce the condition number compared to the EFIE,and still conserve the merit capable of solving arbitrary irregular targets.For each outer iteration,the current is solved by multilevel fast inhomogeneous plane wave algorithm,which will accelerate the matrix-vector multiplication and thus making the inner iteration efficiently.Numerical results demonstrate the accuracy and efficiency of this method.关键词：electromagnetic scattering;improved electric field integral equation;multilevel fast inhomogeneous plane wave algorithm0|2|1更新时间：2025-07-02
- 摘要：An easily-manufactured large-diameter slow-wave structure (SWS) with inner sinusoidal corrugated conductor is investigated in this dissertation.The cold dispersion equations of the SWS and the coupled impedance of high-frequency field in the SWS are derived,calculated and discussed in detail under considering the effect of structure parameters involved on the density of TM0n mode dispersion curves and coupled impedance of TM02 mode.The results show that the period,the wave depth and the beam average radius have influences on the impedance,and that the SWS has some unique advantages:It may suppress mode competition and operate under a low axial guide magnetic field.关键词：corrugated-inner-conductor SWS(Slow-Wave Structure);mode competition;coupled impedance;low magnetic0|2|0更新时间：2025-07-02
- 摘要：An outlier-resistant space time autoregressive (OR-STAR) algorithm is proposed,which can efficiently detect moving targets under nonhomogeneous environment with outliers.The cause of the outlier worsening the moving target detection (MTD) performance of STAR is analyzed.An approach for determining the outliers’ Doppler frequency is proposed,which is based on the local maximum norm value of the weight-vector.Thus,the outliers can be eliminated in turn according to the estimated Doppler frequency.Theoretical analysis and simulation results are presented to demonstrate that,OR-STAR can efficiently eliminate the effect of the outliers for decreasing the detection performance.This approach has the advantage of very small second sample support,which is a very suitable STAP algorithm for engineering application.关键词：space-time adaptive processing(STAP);space-time autoregressive algorithm(STAR);outlier0|2|2更新时间：2025-07-02
- 摘要：Optimum quantization for signal detection can effectively reduce the complexity of realization.Considering finite precision quantization,we analyze the performance of multi-observation signal detection,and prove that multi-observation accumulation is the optimum statistic in real-world signal environments.Furthermore,we propose a novel approach based on genetic algorithm to design optimum quantizers offline,which optimize figures of merit for signal detection such as the equivalent detectability factor.The approach is applied to the design of multi-frame accumulation for infrared dim target detection.Numerical results show that optimum quantization can cut down the conventional 8-14bitsquantization to 2-4bits,thus effectively reduce the complexity of image processing.关键词：signal detection;optimum quantization;accumulation;genetic algorithm0|2|1更新时间：2025-07-02
- 摘要：There are two important factors that affect the performance of Space-Time Adaptive Processing (STAP),that are steering vector mismatch and covariance matrix mismatch.The robust STAP algorithm is proposed that using the worse-case performance optimization.By the problem formulation,the robust STAP algorithm model is based,and is converted to the loading sample matrix inversion (LSMI) algorithm equivalently,the optimal weight vector is obtained in the closed form,via calculating the Lagrange multiplier λ exactly,the exact loading level of LSMI is given,and the difficult problem of finding the optimal loading level for diagonal loading is solved perfectly.Simulation results attest the correctness and the validity of the proposed algorithm.关键词：space-time adaptive processing;steering vector mismatch;covariance matrix mismatch;diagonal loading0|2|7更新时间：2025-07-02
- 摘要：It proposes a method based on ACA (ant colony algorithm) to deal with the data association problem for multi-target tracking.On the one hand,it forms the data association into combinational optimisation problem.On the other hand,it proposes the ACA’s use to solve the combinational optimization problem for data association and constructs the algorithm model.The detailed algorithm developed in this paper is given.Experimental results show that this algorithm is efficient in dealing with the data association for multi-target tracking.关键词：target tracking;data association;ant colony algorithm;pheromone2|3|14更新时间：2025-07-02
- 摘要：Low signal-to-noise ratio target track initiation is one of the major problems in dense clutter environment target tracking.To solve the track initiation problem of a class of target with Doppler measurement,a two-hierarchy Hough transform track initiation algorithm is proposed.By introducing the time index of measurement and using the relationship between the Doppler and range measurement,the algorithm converts the track initiation problem in 3D space to the track initiation problem in two 2D spaces.In addition,four theorems concerning the characteristics of the proposed algorithm are given,which provide guidance for the parameter design of the algorithm.Simulation results show the efficacy of the proposed algorithm.关键词：Doppler measurement;track initiation;Hough transform0|2|15更新时间：2025-07-02
- 摘要：As widely application of the frequency synthesizer with high stability(FS-HS) in the sharing transmitter and receiver system and separating transmitter and receiver systems,however,the conventional methods of analyzing the common frequency synthesizer are not applicable to FS-HS,the signal model for FS-HS is modeled.An approach of low close-in carrier phase-noise which is based on the IF sampling technique to measure FS-HS is presented.This method is used to obtain the phase fluctuation of the frequency synthesizer by IF sampling and signal pre-processing firstly,then adopt the matching filters to search and compensate the first-order and second-order frequency deviation of the signal output by the FS-HS,and finally,calculate to obtain medium-short term frequency stability and low close-in carrier phase noise of the FS-HS.At last,the analyzed result of the real measured data of the high-stable digital frequency synthesizer for a radar is presented.关键词：frequency synthesizer with high stability;frequency stability;low close-in carrier phase-noise;second-order frequency deviation1|2|0更新时间：2025-07-02
- 摘要：We simulate the behavior of real 50GHz samplers used in nose-to-nose(NTN) calibrations by developing a "default" SPICE model of the sampling circuit.The NTN simulated impulse response compares well to measurements through designing the parameters of the model.When our simulated results are similar to measured results,we can estimate of the contribution of the sampling circuitry to the phase error of physical samplers which can not be qualified in the practical measurement.In the end,we study convergence to determine the range of valid simulation conditions for this particular mode that is robust enough to accurately perform numerical experiments for a broad range of parametric studies.关键词：broadband sampling circuit;SPICE-simulation;convergence0|2|0更新时间：2025-07-02
- 摘要：detecting the Moving objects,we proposed a method based on 3D orthogonal Gassian-Hermite moments (3D OGHM) which combined both the temporal and the special characteristics of the video sequences.Then we analyzed and optimized our algorithm thoroughly.And the detail steps to implement 3D OGHM on the computer were provided later.Finally,a visual comparison involving similar methods was given.The experimental results show that the moving targets can be effectively detected and extracted from the image sequences of the complex scenes.Compared with the congener methods,ours can not only suppress the noises efficiently but also have a stronger ability to enhance the motion information.And it also has a robust and real-time performance.关键词：visual tracking;moving objects detection;orthogonal Gassian-Hermite moments;signal to noise ratio0|2|4更新时间：2025-07-02
- 摘要：By using a three dimensional Markov chain and M/G/1/K queue,a performance model was proposed for IEEE 802.11 DCF in finite load,which analyzed the impact of different factors,including number of the terminals,traffic loads,the binary exponential back-off mechanism and the finite queue system at the MAC layer.Based on the model,the closed form of optimum minimum contention window maximizing the throughput under finite load was derived.Simulation results show that the model can evaluate validly the performance of the DCF.By adjusting minimum contention window according to various traffic loads,maximized throughput can be obtained.关键词：traffic load;distributed coordination function (DCF);throughout;Packet delay0|2|0更新时间：2025-07-02
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