最新刊期
卷 31 ， 期 9 ， 2003
- 摘要：This paper focuses on the SAR image understanding on the basis of feature extracting,and proposes a system which can be used to evaluate some man-made targets' hitting effect.This system includes four modules:target detection;target selection;features extracting;two-level hitting effect evaluation.The selection and extraction of features of special targets,such as buildings,are analyzed.After proper improvement this system can be used to evaluate a variety of man-made targets' hitting effect and work as an ATR system.The simulation results show that this system is feasible and effective.关键词：SAR image understanding;features selecting and extracting;hitting effect evaluation2|1654|5更新时间：2025-07-16
- 摘要：This paper introduces a clutter tracking technique used for airborne PD radar.Combining the clutter feature of airborne PD radar and characteristic of local entropy algorithm,we apply this algorithm to the clutter tracking.We propose the judging criteria of similarity to maximum local entropy that is used to segment the simulated data after local entropy filter.The hybrid filter,which is composed of K-nn filter and local entropy filter,has been used to get clutter edge detection.This scheme has been verified to be successful in several typical experiments.关键词：PD radar;clutter tracking;image processing;local entropy;K-nn filter;expert system.2|1368|6更新时间：2025-07-16
- 摘要：We proposed a method on detection of moving object using a fusion algorithm based on segmentation of optical flow field and edge extracted by Canny's operator in the image sequence acquired by a moving camera.This method can be preformed with three steps.In the first step,the segmentation of object area was finished and segmentation map was obtained using motion epipolar constraint and C-Mean value cluster algorithm.In the second step,edge map of object area was established by Canny's edge operator.In the third step,a whole object was detected by a novel fusion method based on segmentation map and edge map.The experiments have shown encouraging results using two sequences of natural images with complex backgrounds.关键词：C-Mean cluster;edge fusion;epipolar constraint;focus of expansion;optical flow3|3450|26更新时间：2025-07-16
- 摘要：According to the process of adaptive finite element analysis,a multigrid implementing method based on hierarchical basis is proposed.It can be implemented much easily due to rather simple form of the restrictor operator R used in the analysis.A test example shows that the present method possesses high computing efficiency.关键词：multigrid method;adaptive refine;hierarchical basis2|1675|2更新时间：2025-07-16
- 摘要：A shaped beam base station antenna is realized with the unequal spacing array using an optimization technique based on genetic algorithms.Antenna model have been evaluated by using the Method of Moment (MoM).During the antenna optimization process,an appropriate fitness function is used to suppress the sidelobe in interference zone,fill the null points in service zone and control the back lobe,to get satisfactory pattern shape in the whole frequency band.As a result of this optimization,a practical shaped beam antenna with suppressed sidelobe smaller than -18.32dB and backlobe -26dB,filled null point larger than -14.71dB was achieved.The proposed method is closer to reality compared with previous methods and can be used to optimize complicated antennas.The result is very useful for engineering and theoretic analysis.关键词：genetic algorithm;shaped beam;base station;method of moment;sidelobe suppression;null filling2|1817|4更新时间：2025-07-16
- 摘要：The middleware for the heterogeneous distributed systems is one of the hotspots for research.And it is also fearfully focused in the electric power field.The article concludes that it is valid to integrate the respective advantages of JAVA and CORBA to implement the middleware,which is applied to the heterogeneous distributed systems in the electric power control center.That is the first time to be attempted in national electric power field.The crust of the middleware is JAVA and the kernel is CORBA.This idea is proved to be correct in practice.And the middleware for the data exchanging can be suitably applied to the electric power control center.At last,the keys of the project are discussed.关键词：distributed systems of heterogeneity;middleware;the capability of Input/Output;connection pool2|938|2更新时间：2025-07-16
- 摘要：Because of the FPGA's parallel pipelining processing features,this paper designed and implemented the real time CIF format image DCT using Exilinx Company's 500000 gate grade chip XCV400E.Using ping-pong model,C×F×CT is implemented only by designing one fast algorithm model (F×CT).Digital video signal is input to FPGA line by line.Controlling by horizontal sync and vertical sync,every group data of 8 pixels as a vector is input and is multiplied CT i.e.(F×CT).The computed results are stored as transform format.Each pixel needs one (1×8)×(8×8) matrix operations.Each line needs 352×(1×8)×(8×8) times matrix operations.44times (1×8)×(8×8) matrix operations results need storing as transform format (HT=(F×CT)T).When next 8 line data are input,they are processed with the same way as the above.For the last 8 line's first processed results (F×CT),they are read out and processed as (HT×CT).The final results are output as transform format (GT=C×H).Therefore,the continuous real-time whole field pix DCT transform C×F×CT is finished.Function and timing simulation and the successful connection with TMS320C62X system verified the design and implement.关键词：DCT;ping-pong model;parallel pipelining process3|1806|11更新时间：2025-07-16
- 摘要：A single S-parameter is sufficient for small-signal networks analysis,but more mathematical tools are needed to describe and interpret the data resulted from large-signal networks analysis.In this article,a novel describing function is adopted to describe nonlinear characteristic of RF power components:nonlinear scattering function.The nonlinear scattering function can build accurate model of RF power components under large signal.关键词：nonlinear scattering function;RBF neural network;black-box model in frequency domain2|1286|2更新时间：2025-07-16
- 摘要：The small-scale artifacts generated by aliasing noise existing everywhere in an image,bring difficulties to some applications,such as target identification.Eliminating aliasing noise algorithm used in push-broom CCD image gathering system is derived and optimized.The strategies for CCD push-broom scanning and the novel methods for data processing are proposed.Aliasings in image are eliminated although CCD array can only move in one direction in remote sensing imaging system.The relative scan error must be less than 1/4 of CCD interval.The results of images processing experiments verify the validity of aliasing noise processing methods.关键词：aliasing noise;CCD linear detector array;remote sensing;spatial frequency2|865|2更新时间：2025-07-16
- 摘要：An efficient implement for Algebraic Reconstruction Technique (ART) is presented in this paper.The coefficient matrix in the original ART is split into radial matrix and the coefficient matrix of the radial.The slope and intercept of each radial are kept in the radial matrix.The coefficient matrix of the radial is calculated before iteration,and considering the correlation of the lines with the same projection angle it can be computed iteratively,with much time saved.The experiments using Shepp-logan phantom show that the results of this method are as good as the traditional one with great reduction of memory.关键词：algebraic reconstruction technique;image reconstruction;memory optimization;iterative algorithm2|1236|5更新时间：2025-07-16
- 摘要：A three-channel real-time clutter simulator for Doppler radar is developed by applying a new real-time signal reconstruction and modulation technic.Windowing and overlapping the series time domain sequence instead of simple combination,the ratio of signal to noise increases from 30 dB to 60 dB.At the same time,we refrain mirror frequency effectively with the method of digital quadrature modulation (DQM).关键词：pulse Doppler radar;clutter simulation;signal reconstruction;DQM2|1012|1更新时间：2025-07-16
- 摘要：A miniature stereo vision machine to generate high-resolution dense depth maps has been developed for application to portable intelligent robots and smart visual interface.The machine uses multiple cameras,each with a very wide field of view,to synchronously capture stereo image sequences,and then computes dense depth maps in real time. The whole algorithm,including radial distortion correction,LoG filtering,correspondence finding,and dense depth map computation,is compactly implemented in a single FPGA.The machine,running at 60Mhz,could achieve more than 30 fps for building dense disparity maps with 320×240 pixels in 64-pixel disparity search range and 8-bit depth precision.关键词：stereo vision;dense depth map;FPGA;real-time computing;miniature system2|1141|4更新时间：2025-07-16
- 摘要：Cache affects RAID performance very much.Considering disk parameter and channel performance,we use queue theory and Petri model to calculate RAID performance,and analyze influences of disk and Cache parameters in theory,then provide some methods to improve RAID performance.关键词：RAID;cache;I/O response time;throughout2|1185|4更新时间：2025-07-16
- 摘要：Based on the analysis of the internal relation between learning ability and generalization ability of the overfitting of BP neural network,by the introduction of mulit-correlative coefficient to manifest the complexity of the function,a quantitative uncertainty relation between the fitting relative error of training sample sets and the testing relative error of verifying sample sets,which describe the learning ability and the generalization ability of BP network,respectively,was revealed in the overfitting of BP neural network.Tests of numerical simulation for multi-kinds of different functions were carried out to determine the value distribution (0.007~0.07)of overfitting parameter q in the relation.Based on the quantitative relation,the training method for the improvement of generalization ability in the training process of sample sets using BP neural network was given.关键词：BP neural network;learning ability;generalization ability;overfitting relation3|1057|6更新时间：2025-07-16
- 摘要：It discusses the multicast routing problem with QoS constraints and describes a network model that is suitable to research such routing problem.The paper mainly presents a dynamic QoS multicast routing protocol(DQMRP).The DQMRP can operate on top of the unicast routing protocol.It only requires the local state information of the link(or the node),but does not require any global network state to be maintained.The DQMRP can significantly reduce the overhead for constructing a multicast tree with QoS constraints.In DQMRP,a multicast group member can join or leave the multicast session dynamically.The protocol can search multiple feasible tree branches,and select the optimal or near-optimal branch for connecting the new receiver to the multicast tree if it exists.The proof of correctness and complexity analysis of the DQMRP are given,and the performance measures of the protocol are evaluated using simulation.The study shows that DQMRP provides an available approach to multicast routing with QoS constraints.关键词：QoS routing;multicast routing;protocol;dynamic multicast routing;QoS constraints;NP-complete2|993|17更新时间：2025-07-16
- 摘要：Information technology security evaluation criteria GB 17859 represents the security metrics of information systems as different ratings and defines the security elements set for the security metrics evaluation.The concepts of composition independent security element,composition complementary security element and composition correlated security element are introduced to discriminate between the various characters of the security elements presented in the process of security metrics assessment.The formal evaluation model for information system security metrics and its implementation are also introduced based on the definitions of access path,regular path and the relationship between components.关键词：security metrics;evaluation;composition independent security element;composition complementary security element;composition correlated security element;access path4|1776|11更新时间：2025-07-16
- 摘要：In recent years,researches of ship detection using synthetic aperture radar (SAR) images have received considerable attentions in the area of marine remote sensing.The origin and development of ship detection in SAR imagery is reviewed.The physical factors that would affect ship and wake are analyzed.The ship detection algorithms and wake detection algorithms are reviewed,summarized and contrasted respectively.The future direction of research and development is viewed.关键词：synthetic aperture radar;Target Detection;automatic target recognition3|4159|26更新时间：2025-07-16
- 摘要：Recent developments in microfabrication have produced new opportunities in vacuum electronics.The variety of microfabrication applications in vacuum electronics is steadily growing.The impressive achievements are field emitter arrays(FEAs) for cold cathodes.A new class of microfabricated vacuum electron devices or "μVED" will make the microwave/millimeter wave tubes miniature and low costs.They will also work in terahertz frequency with power output up to 1W.关键词：microfabrication;vacuum microelectronics;terahertz technique2|1603|16更新时间：2025-07-16
- 摘要：Coaxial-to-rectangular waveguide transition of end launcher has been analyzed and computed detailedly.But the coaxial-to-rectangular waveguide is rarely used as a radiation element for it is difficult to match with free space.This paper applies both loop coupling approach and FDTD method to analyze the three-dimension non-even antenna element,not only reduces computing time and volume,but also improves the accuracy,then gets the radiation pattern and VSWR characteristic figure,proves it with experiment,and solves the match problem of free space.The research proves that this phased array radar element has characters of broadband、big scanning angle,which can be used in ground、airborne and satellite phased array radar or communication system.关键词：coaxial-to-rectangular waveguide end launcher;loop coupling approach;FDTD method2|1554|0更新时间：2025-07-16
- 摘要：Prohibitive computation resources and too much time are needed for EMC analysis of complicated EM environment.To overcome this drawback,a parallel algorithm that combined MoM with MPI functions is studied,and performance of parallel MoM on PC clusters is measured.Numerical results show that the parallel MoM on PC clusters can be efficiently employed to analyze EM feature of complex targets at very low cost because no special workstation is needed.关键词：PC clusters;Parallel MoM2|870|5更新时间：2025-07-16
- 摘要：A four-beam-switched antenna is analyzed and designed.Firstly,a microstrip Butler matrix is used as the beamforming network,in which the 90° hybrid is realized by a 3dB directional coupler.The S parameters of the network are computed and measured.Then,the planar array used to obtain the desired beam pattern is analyzed and synthesized.Finally,the experimental results of the prototype antenna are given.关键词：switched-beam antenna;microstrip Butler matrix;planar array2|1548|4更新时间：2025-07-16
- 摘要：The conclusion is derived that the LPDA has no strictest phase center but has an approximate phase center .Approximate phase centers can be defined by computing the local curvature of a far-field constant-phase surface on the antenna's principal lobe.The phase centers computed from each pattern are situated in the radiation section of LPDA and ,moreover,track differently with frequency.关键词：log periodic dipole arrays;approximate phase center2|1997|7更新时间：2025-07-16
- 摘要：This paper proposes a novel chaotic ADC,which is a kind of non-pipeline ADC based on nonlinear map,and the circuit design based on switch-capacitance for this ADC is also proposed.The theoretic analysis and simulated results show that the ADC proposed overcomes the problems of the gain mismatches between stages and the mismatches between A/D and D/A in single stage in the pipeline ADC,which severely infect the precision of ADC,and is not sensitive to noises and the requirements in precision for some components used for the system.Therefore,with this approach we may achieve a conversion at high speed and precision.关键词：chaos;symbolic sequence;A/D converter2|930|0更新时间：2025-07-16
- 摘要：The matching result is very easy to be wrong due to the uncertainty of searching scope on disparity during stereo matching.A novel stereo matching algorithm is developed,whose criterion is the minimum of absolute disparity combined with gray correlation multi-peak value method.It is pointed out that the corresponding point with maximum of gray normalized correlation coefficient is not the correct matching point completely by analyzing maximum of gray normalized correlation coefficient matching approach,so gray correlation multi-peak value matching method is mentioned to obtain initial matching aggregation in the paper.Disparity gradient restriction is used to optimize the initial matching aggregation partially.The method,whose criterion is the minimum of absolute disparity,is used to ascertain the only matching point.It is proved that the algorithm proposed in the paper is feasible by 3D reconstruction on an object (deflection yoke,DY)with complex and irregular surface,and a standard piece with given 3D coordinates,which can meet the demands for measuring in non-contact the 3D coordinates of object,such as DY,with irregular surface precisely.关键词：stereo matching;disparity;gray;measurement;searching scope2|915|3更新时间：2025-07-16
- 摘要：A method for planar near-field to far-field transformation based on element current reconstruction is presented and the basic principle of this method is given.The results of computer simulation show that this method does not require the sampling interval to satisfy the Nyquist sampling criteria and only needs few sampling points to attain very high testing precision,so we can improve the testing speed and effectively reduce the truncation error caused by finite scanning plane on the premise of ensuring the testing precision.Therefore,the method presented in this paper is quite suitable for the planar near-field measurements with large phased array antennas.关键词：element current;reconstruction;planar near-field to far-field transformation;array antenna;Nyquist sampling criteria;testing speed;truncation error2|925|0更新时间：2025-07-16
- 摘要：TCP performance in wireless ATM networks is analyzed in this paper.The throughput efficiency formula is induced and the throughput efficiency-CER relationship is demonstrated for several TCP segment length according to the characteristics of wide area networks traffic distribution.By simulations on OPNET,the theoretical analysis is proved to be reasonable and some conclusions are drawn.Furthermore,the optimal TCP segment length is analyzed.Then it is presented that TCP segment value should be adjusted according to CER in order to get the best throughput efficiency.2|974|0更新时间：2025-07-16
- 摘要：The optimal weighted spatial smoothing(WSS)technique proposed in[1]is capable of de-correlating the coherent sources perfectly,with the equivalent sources covariance matrix diagonal.Based on the fact that the optimal weight matrix in[1]is a function matrix of source directions and the array covariance matrix after optimal WSS is Toeplitz,a new cost function is constructed.The bearing estimates can then be achieved by virtue of a genetic-algorithm-based Toeplitz matrix fitting.Compared with[1],the proposed algorithm can be realized without the a priori knowledge about source directions and de-noising preprocessing.The Monte-Carlo simulation results demonstrate that the new algorithm is highly superior to the conventional SS(spatial smoothing)technique in the resolving ability for spatially-closed coherent sources,especially in the case of small array size.Besides,the comparison of new methods with maximum-likelihood methods is also presented.关键词：direction-of-arrival estimation;coherent sources;Toeplitz matrix;matrix fitting;genetic algorithms2|1825|11更新时间：2025-07-16
- 摘要：All backscattering field's intensity from conducting plate can be calculated by complex ray method,especially complex ray paraxial approximation in angle domain through modeling the conducting plate.In the meantime the calculating accuracy of the field's intensity can be controlled by modulating complex ray expansion parameter ξ.Comparison between the numerically calculated result and analytic solution proves that the method used in this paper is efficient and correct and it is applicable to other cases.关键词：EM scattering;conducting plate;complex ray method;complex ray expansion parameter2|842|0更新时间：2025-07-16
- 摘要：This paper is the first one of the paper series on hybrid filter banks based ADC.The operation principle of hybrid filter bank based ADC is presented.A design of ADC based on hybrid filter banks is implemented by using z-s Transform and IFFT,and the HFB has -75dB average aliasing error.And it is derived that time-interleaved ADC is the special case of the hybrid filter bank based ADC.关键词：analysis filters;synthesis filters;hybrid filter banks;spurious free dynamic range2|941|2更新时间：2025-07-16
- 摘要：A method to eliminate the correlation of signal sources is proposed,which can help to estimate the signal sources' DOA through randomly changing the spatial gain.The expense of receivers are separated from the number of the correlative sources in this algorithm which greatly reduces the expense of receivers.The load of calculation is also light.Theoretical analyses and computer simulation verify that the method is practical,effective and easily achieved.关键词：DOA;spectral estimation;correlation2|838|0更新时间：2025-07-16
- 摘要：Because the morphological top-hat operator can extract the local optima of an image,this paper applies it to two main fields of multisensor image fusion:multifocus image fusion and panchromatic and multispectral image fusion.In experiments,our methods are compared with the algorithms based on Laplacian pyramid,wavelet transform,and principal component analysis.The results show that our approaches outperform the others,and exploit the application scope of the top-hat operator.关键词：images fusion;mathematical morphology;top-hat operator2|1084|4更新时间：2025-07-16
- 摘要：Radar range/time sidelobe suppression filters are usually designed only to reduce the sidelobe to the level as low as possible,and the loss in process gain (LPG) is not specially considered.In some cases the LPG is large enough to influence the detection of weak signals.The sidelobe suppression filters with LPG arbitrarily given are proposed,and the design approach of optimal integrated sidelobe level filter and optimal peak sidelobe level filter both with constant LPG is given.关键词：range sidelobe;time sidelobe;sidelobe suppression;loss of process gain;binary phase-coded radar2|2021|5更新时间：2025-07-16
- 摘要：Non-repudiation,as one of the basic network security services,must provide mechanisms in which evidence will be generated,collected and maintained to protect the transacting parties against any false denial in which a particular event or action has taken place.In addition,fairness is a desirable requirement such that neither party can gain an advantage by quitting prematurely or otherwise misbehaving during a transaction.Aiming at solving a serious bug: the selective receipt problem in the current ISO/IEC 13888 non-repudiation mechanism,which is induced by unfairness,this paper presents a Fair non-repudiation protocol FNORP and through a strict formal analysis.We show that FNORP possesses the capabilities of non-repudiation,fairness and timely-termination.关键词：non-repudiation;fairness;timely termination;off-line TTP2|847|1更新时间：2025-07-16
- 摘要：Fast and automatic segmentation and tracking of video object is a key technology in object-based video coding.A algorithm for extracting and tracking moving object is proposed.First,a binary motion image is achieved based on high order statistics detection and motion information of multiple frames.Then,an improved watershed algorithm is used to segment motion region and its surrounding areas.Thus the moving object with fine edges can be extracted with the spatial and temporal segmented results.Finally,a new algorithm is proposed to efficiently track moving object.Experimental results show that the proposed algorithm is efficient.关键词：video object segmentation;segmentation of limited region;improved watershed algorithm;motion track3|1151|5更新时间：2025-07-16
- 摘要：Based on the statistical property of the non-line-of-sight(NLOS)propagation in the mobile communication environment ,an effective location method is presented to mitigate the influence of the NLOS propagation.First,the excess delay caused by the NLOS propagation is estimated using the measured time of arrival(TOA)and the statistical property of NLOS propagation; and then the excess delay is removed from the measured TOA to estimate the line of sight(LOS)propagation time and the position location of the mobile station(MS); finally,the position locations of the MS of different time are smoothed to improve the precision of the position location of the MS.The location of the MS estimated by this method is unbiased.The method does not increase the cost.It is a simple and practical method.Its effectiveness is verified by the simulation results.关键词：time of arrival(TOA);position location(PL);non-line-of-sight(NLOS)propagation;maximum-likelihood(ML)estimation3|1894|16更新时间：2025-07-16
- 摘要：In real face recognition systems,face localization is always heavily affected by complex background,uncontrolled lighting condition and low imaging quality.To solve these problems,a novel face localiztion method in natural indoor environment is presented.The main idea is to use the strong symmetry and the three-dimensional property of human face.Firstly,edge map of original image is obtained by using the Gaussian-derivative operator.Secondly,we introduce some novel rules to the generalized symmetry tranform and radial symmetry transform to localize the glabellum,and then to estimate the scale factor.Finally,accurate eyes localization is realized with similar idea.The results of some experiments are also given which show the robustness and effectiveness of this method.关键词：face localization;symmetry transform;Gaussian-derivatives4|1376|2更新时间：2025-07-16
- 摘要：In the summer of 2001,the ground moving target indication (GMTI) of an airborne battlefield reconnaissance radar was first tested in China and the data of two real channels were recorded.This paper presents some processing results,including DBS imaging of ground scene,detection and interferometric location of ground moving targets which fall in sidelobe clutter,space-time adaptive procession for detection of ground moving targets in mainlobe clutter.关键词：ground slowly moving target detection;DBS;space-time adaptive processing(STAP)3|1220|3更新时间：2025-07-16
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