最新刊期
卷 28 ， 期 7 ， 2000
- 摘要：Two-scale IR imaging model of sea surface based on rigid object is built in this paper.The radiant properties of sea surface are discussed from the aspect of passive imaging.The emulational results based on this model shown that it is a good model to explain the effect on IR passive imaging of sea surface by wind.关键词：sea surface;IR imaging;passive imaging;radiancy;emissivity0|2|0更新时间：2025-07-02
- 摘要：The time-variant fractal surface is adopted to describe regional dynamical feature of natural rough surface.Under three rational assumptions on electromagnetic scattering,the time-domain property of scattering field is analyzed qualitatively by applying Kirchhoff solution,and the fractal model of clutter from natural rough surface is deduced.According to the fact that wavelet detail coefficients of random fractal signal are approximately uncorrelated,the method based on wavelet-based whitening filter and correlation detection is proposed with detailed theory.Theoretical analysis and experimental results prove that the clutter matches the fractal model and the proposed method is effective on detecting target.关键词：natural rough surface;clutter;fractal model;whitening filter;correlation detection0|2|0更新时间：2025-07-02
- 摘要：An extension of Equivalent Small Parameter(ESP) method to analysis of PWM feedback controlled power converter systems,together with its basic principle and derivation of solutions,is presented in detail.The symbolic expressions of steady-state DC outputs,duty cycle and output ripples are given,which can be used to explain the relationships among duty cycle,ripples and switching frequency.It is confirmed by the examples that the proposed method offers the advantages of both simplicity and accuracy.关键词：switching power converter;closed-loop systems;symbolic analysis0|2|1更新时间：2025-07-02
- 摘要：Conventional multiuser interference canceling is always done in the uplink.In this paper,a novel multiuser processing scheme used in the downlink of TDD-CDMA (Time division dupler-code division multiple access) systems is proposed.In TDD-CDMA systems,the downlink multipath channel parameter can be estimated from the uplink.In this paper,we use the instantaneous channel parameter to calculate the spreading spectrum code and despreading code for different users.We present the optimal criterion of the generation of the spreading code and despreading code,so that the multiple access interference can be greatly reduced.Numerical results show that our scheme can geratly increase the signal to interference and noise ratio,compared with conventional CDMA systems which use Gold sequence as the spreading code.关键词：TDD-CDMA;multiuser;multipath;signal to interference and noise ratio0|2|1更新时间：2025-07-02
- 摘要：This paper proposes a new kind of sub-rating channel assignment strategy in cellular mobile communication systems——the Sub-Rating Compact Pattern based Channel Borrowing assignment strategy (SRCPCB).This strategy introduces the concept of sub-rating channel to CPCB(Compact pattern based channel borrowing),and significantly reduces the forced termination probability at the expenses of temporarily degrading the voice of quality of partial calls.Through the simulation on various traffic loads,we obtain some system parameters of performance,such as blocking probability,forced termination probability and degradation of voice quality.The simulation results show that,the SRCPCB overall performance outperforms that of FCA(Fixed channel assignment),DCA(Dynamic channel assignment),BCO,BDCL,CPDCA,CPCB and some other strategies.It will be very important to alleviate the problem of spectrum limitation and enhance the performance in cellular mobile communication systems.关键词：cellular mobile communication;sub-rate;compact pattern;channel borrowing;channel allocation0|2|7更新时间：2025-07-02
- 摘要：The way of bandwidth consummation by ABR (Available bit rate) service in ATM (Asynchronous transfer mode) networks is analyzed,and some charging schemes in literature are summarized in this paper.A new charging scheme for ABR service,a fairness definition for bandwidth allocation and a corresponding bandwidth allocation algorithm are presented.Simulation result shows that this scheme is not only easy to implement,but also overcomes the drawbacks of other schemes,such like bad fairness and poor flexibility.关键词：charging scheme;bandwidth allocation algorithm;ABR service;ATM networks0|2|0更新时间：2025-07-02
- 摘要：In this paper,KM sequence is presented as a potentially spreading code for CDMA (Code division multiple access) system with RAKE receiver.First,based on a RAKE receiver modeling,the performance of CDMA system with RAKE receiver is analyzed,and the properties of PN sequences that are suited to the CDMA system with RAKE receiver are showed.Next,the advantages and disadvantages of KM sequences as spreading codes for CDMA system with RAKE receiver are analyzed systematically.Finally,the cross-correlation functions between m sequence and KM sequence,and the average bit error probability (BEP) corresponding to both the sequences and Gold sequence under correlating receiver and RAKE receiver,are compared.The feasibility of KM sequence as spreading codes for CDMA system with RAKE receiver is verified.关键词：KM sequence;CDMA system;RAKE receiver;cross-correlation;average bit error probability0|2|15更新时间：2025-07-02
- 摘要：Estimation of Rayleigh fading channels using time multiplexed pilot symbols in WCDMA (FDD) is considered.Method of interpolation on a second-order curve using the instantaneous channel estimation of two successive slots based on least square method is presented.It is demonstrated by computer simulations that the channel distortion on data symbols in a slot can be estimated effectively compared to the method using simple linear interpolation,and the performance of the Rake combiner is improved especially in fast moving cases.关键词：the third generation mobile communication;WCDMA;RAKE receiver;least square method0|2|3更新时间：2025-07-02
- 摘要：This paper proposed a new self-healing mechanism based on pre-designed survivable ATM (Code division multiple access) multicast tree,which considers any single link and node failure case.All the links on the multicast tree are included by different protection cycles.The node-neighboring protection cycles are connected by the connecting path which doesn't pass through the common nodes of the neighboring cycles in order to avoid loop.When detecting the failure,the associated protection cycles and connecting paths are active.The simulation results show the efficiency and reliability of the proposed mechanism.关键词：self-healing mechanism;ATM multicast tree;protection cycle0|2|0更新时间：2025-07-02
- 摘要：Two alternate routing algorithms are proposed for dynamic Routing and Assignment of Wavelength (RAW) problem in multi-fiber Wavelength Division Multiplexing (WDM) all optical networks.The RAW problem is equivalent to supporting as many lightpaths as possible in the corresponding layered-graph.By virtue of layered-graph,routing and assignment of wavelength subproblems can be considered simultaneously.Simulation shows that layered-graph-based RAW algorithms perform better than the existing ones.关键词：multi-fiber WDM networks;dynamic RAW;layered-graph;alternate routing algorithm0|2|1更新时间：2025-07-02
- 摘要：In this paper,the general dispersion relation of Magetostatic Surface Wave (MSSW) wide modes propagating in narrow YIG (Yttrium iron garnet) multilayer sample with arbitrary parameters is constructed.The theory is suitable to research all the situations of MSSW dispersion controlled by multilayer films and is better in agreement with the actual situations.The dispersion of MSSW wide mode in 2 period multilayer films with finite width was numerically investigated by applying the theory and high order wide modes in finite sample were derived.Numerical results show that the dispersion of MSSW wide mode can be controlled efficiently by means of changing the parameters of the multilayer and also influenced by sample width.Experiments were performed at frequency range 4.2~5.2 GHz in YIG multilayer samples of different width and the experimental results are coincident with the theoretical analysis.关键词：YIG thin film;magnetostatic surface wave;multilayer films;dispersion;width mode0|2|1更新时间：2025-07-02
- 摘要：The improvement between the balance sequence that achieves Welch's lower bound and the ordinary sequence is estimated in this paper. And we prove that it reduces to zero when the length of the sequence becomes infinite.In addition,the statistical characteristics on the diverse correlation functions are calculated including GMW,No,Bent or OB sequences and their truncated ones.The results indicate that the application of these sequences in the CDMA (Code division multiple access).systems is viable and eligible.关键词：CDMA;correlation property;balance sequence0|2|1更新时间：2025-07-02
- 摘要：Asynchronous transfer mode adaptation layer type 2 has been designed for efficient transport of voice,fax and voiceband data over an ATM (Asynchronous Transfer Mode) virtual circuit.High statistical multiplexing gain can be achieved by applying suitable compression methods on voice,fax and voiceband data and using silence detection and elimination on voice calls.This paper analyzes the deficiencies of the model M/D'/1/K and builds a M'/D/1/K model on the AAL2 (ATM Adaptation layer type2) packet voice multiplexer where M denotes the Poisson process with the state dependent average arrival rates.Its performance is also analyzed.Simulation results show that the M'/D/1/K model works well with the AAL2 packet voice multiplexer with bit dropping at the input port.关键词：AAL2;bit dropping;packet voice;statistical multiplexing0|2|3更新时间：2025-07-02
- 摘要：Low frequency jitters and wanders caused by pointer adjustments in SDH networks have been found to be a big obstacle for the interconnection between SDH and non-SDH networks.This problem can be solved or improved by using a very narrow bandwidth Phase-Locked Loop for jitter and wander suppression at the output tributary interface in SDH systems.An all digital Phase-Locked Loop characterized with a very narrow bandwidth and a wide frequency capture range is presented in this paper.With a simple structure,this PLL is quite feasible for multi-PLL integration for E1 interfaces in an SDH system.关键词：AN;SDH;PLL;jitter;wander0|2|1更新时间：2025-07-02
- 摘要：In fully digitized QPSK (Quadrature phase shift Keying) demodulator,sometimes there exists a rather large frequency-offset so that the demodulator can not work normally.This paper proposes a novel algorithm to solve this challenging problem.Instead of estimating frequency-offset directly,we estimate the period of some new sequence,resulting in a good statistic for frequency-offset estimating.The algorithm is less expensive computationally in rectifying frequency-offset,and has been applied to a multi-channel QPSK demodulation system,which is implemented with a single DSP(Digital signal processing) of TMS320C6201.关键词：frequency-offset estimate;fully digitized receiver;QPSK demodulation0|2|3更新时间：2025-07-02
- 摘要：The paper investigates a new blind multiuser detector based on higher order cumulants.First,a new optimizing criterion is proposed and proven to have the global minimal value,while the minima satisfy the decorrelating conditions.Thereby,a new scheme for the blind multiuser detection can be obtained.Then,by means of an unconstrained equivalent form of the criterion,a blind adaptive algorithm is given.The simulation results show that the method possesses stronger capability of suppressing interference.关键词：CDMA (Code division multiple access);blind multiuser detection;higher order cumulant0|2|6更新时间：2025-07-02
- 摘要：Based on Fuzzy Neural Networks (FNN),a sliding mode adaptive control methodology is presented for a class of nonlinear systems represented by input-output models.There are two parts in the controller design:one is the design of the Fuzzy Neural Networks Sliding Mode Controller(FNNSMC) and the other is the design of the linear feedback system.The FNNSMC,where the FNN is used to fulfil the sliding mode control,can eliminate the chattering by smoothing the control signal while the bounds of the uncertainties and the disturbances of the systems are not known in the controller design.By the Lyapunov's stability theory,we have proved that the system is globally stable and the tracking error can be converged to the neighborhood of zero.关键词：nonlinear systems;fuzzy neural networks;sliding mode control;adaptive control0|2|9更新时间：2025-07-02
- 摘要：In this paper,we propose a novel architecture of active networks based on plug-in,with which services can be introduced rapidly and flexibly.We also propose a new model for ticket order service over Internet.The simulation result indicates that using active networks,both the latencies of networks and the load of servers are reduced.关键词：active networks;service;capsule;plug-in0|2|1更新时间：2025-07-02
- 摘要：In low earth-orbiting (LEO) satellite mobile communication systems,frequent handover requests exist because of the relative motions between the satellites and the mobile users.In order to decrease the handover requests for systems saving,two access schemes besides the distance-prioritized scheme are proposed in this paper.One judges the priorities by estimating the overlaid time,the other scheme additionally considering the elevation angle performance.A non-uniform distributed global traffic model is also constructed.By emulating the global traffic service through a LEO satellite mobile communication system under different access schemes,the performance of the networks are analyzed.关键词：satellite mobile communication;handover;access scheme;traffic model1|2|0更新时间：2025-07-02
- 摘要：In wire rope test,an important characteristic is to identify the features of wire rope flaw signals in frequency domain.Based on wavelet transform techniques,a new demarcation method in space domain and a new frequency feature extractive method for local wire rope flaw signals are proposed in the paper.Furthermore,the types of wire rope flaws can also be identified by the wavelet network quantitatively.The experimental results show that the proposed method can clearly distinct the noise and flaws in wire rope flaw signals.Using proposed method in this paper,the performance of wire rope flaw detective instrumentation can remarkably improved.关键词：wavelet transform;feature extraction;wire rope;local flaw signal;wavelet network0|2|170更新时间：2025-07-02
- 摘要：A new interpretation of the membership degree of the fuzzy C-means algorithm is presented on the basis of competitive learning and then a new algorithm called rival checked fuzzy C-means algorithm is developed.The theoretical analysis and experimental results show that the new algorithm improves the convergence speed of the fuzzy C-means algorithm.关键词：fuzzy c-means algorithm;membership degree;competitive learning4|2|1更新时间：2025-07-02
- 摘要：This paper presents a recognition method of Chinese continuous speech,in which phonetic and prosodic features are integrated in terms of 3-Dimension Viterbi search.The phonetic information is modeled by 60 phonemic HMMs and the prosodic information by 8 tone HMMs.Both recognitions are synchronized based on 3-Dimension Viterbi search.A frame-synchronous parsing algorithm for CFG based on a top-down strategy is used for parsing processing.The task is related to the hotel reservation process,of which the perplexity is 27.3.For 1070 utterances produced by each of ten speakers,the average sentence recognition rate was 94.4%.关键词：recognition of Chinese continuous speech;phonemic HMM;tone HMM;3-Dimension Viterbi search0|2|1更新时间：2025-07-02
- 摘要：In this paper,we present a new method on X-CT image reconstruction from finite angle projections data.In this way, firstly characteristic parameters are extracted from X-CT finite angle project data,then some truncated singularity functions are constructed using those characteristic parameter,and finally X-CT images are reconstructed by those truncated singularity functions.Thus non truncated artifacts X-CT image from finite angle project data can be gained.Experimental and simulated results show that this method gives much better reconstructed image than available methods.关键词：truncated singularity function;singularity points;truncated spectrum0|2|0更新时间：2025-07-02
- 摘要：Based on analyses of GA's properties,a novel algorithm,the immune algorithm—IA,is proposed with analogies to the concept and the theory of immunity in biotic science.The core of the algorithm lies on constructing the immune operator that is realized by vaccination and immune selection.IA is approved theoretically convergent.The strategies and the methods of selecting and constructing a vaccine for TSP are given in this paper.A simulation test of 75-city TSP is done with IA,and its computational process is compared with that of canonical genetic algorithms.The results show that IA can evidently alleviate the undulate phenomenon at the end of the evolutionary process,therefore increases the convergent speed.关键词：the immune algorithm;antibody;convergence;TSP0|2|4更新时间：2025-07-02
- 摘要：This paper proposes the method to measure perceptual quality of compressed video which is based on human visual features,video contents and Fuzziness.The key of the method is to compute the visibility threshold.The paper analyses the visual features and the video features which are related to quality metric for compressed video.We design the architecture for measuring perceptual video quality.The elevation factors for visibility threshold are calculated based on fuzzyiness.Perceptual PSNR is proposed for measure of compressed video.关键词：visual features;video features;compressed video quality0|2|20更新时间：2025-07-02
- 摘要：In this paper,the formulae are indicated firstly to design artificial reverberator.After analyzing the properties of two reverberators,a connection in series all-pass reverberation system has been addressed in detail.This system is designed based on the artificial reverberation formulae,as well as the operation complexity.The simulation of echo density,which is the crucial reverberation factor,is analyzed.At last,the principles to design the system parameters and the solution to reckon the reverberation time are proposed.Experimental results confirmed that not only coloration and flutter had been eliminated completely but also the echo density is consistent to the room acoustics,and the natural reverberation effect could be simulated vividly.关键词：early reflection;subsequent reverberation;comb filter;coloration;flutter0|2|0更新时间：2025-07-02
- 摘要：A new classification of video signal processors based on parallelism is first presented in this paper.Then an overview of parallel architectures of video signal processors is given and the future development of parallel architectures is pointed out.关键词：parallel architecture;parallelism;video signal processor0|2|1更新时间：2025-07-02
- 摘要：Micro Satellite has attracted people's interests because of its particular fascination.This paper analyzes the technical characters of micro satellite according to its present research situation and summaries some design strategies based on its characters.At the end,some viewpoints for development direction of micro satellite are presented.关键词：micro-satellite;multifunctional structures;MEMS (micro electronic mechanical system);satellite network0|2|1更新时间：2025-07-02
- 摘要：WLAN(Wireless local area network),an integration technology of Internet and mobile communication,is one of the solutions to realize "the last mile".This paper presents four kinds of location management of WLAN to analyze their performance with wireless distribution system and wire distribution system respectively.The results prove that strategies a and d are suitable for wire distribution system and strategy d is the best method for wireless distribution system.关键词：WLAN;MAC(Medium access control);distribution system;wireless media;wire media0|2|2更新时间：2025-07-02
- 摘要：Two-dimensional prime sequence codes for synchronous fiber-optic CDMA (Code division multiple acess) network is derived from modified prime sequence codes.The bit error probability performance of the proposed system using an avalanche photodiode (APD) is analyzed where the Gaussian approximation of the APD output is employed and the effect of the APD noise,thermal noise,and multiple access interference are considered.Numerical results reveals that the performance of 2-D FO(Fiber optic)-CDMA system is much better than that of 1-D FO-CDMA system and the bandwidth occupied by 2-D FO-CDMA system is relatively small.关键词：fiber-optic CDMA;prime sequence codes;two-dimensional optical orthogonal code0|2|1更新时间：2025-07-02
- 摘要：The performance surface of an adaptive filter has some useful geometrical characteristics.According to those characteristics,we present an FIR.Adaptive Geometrical Center Method (FIRAGCM) firstly in this paper,then we get a globally convergent IIR method based on the AGCM,named IIRAGCM,by transforming the performance surface of an IIR filter.Being different from the gradient algorithm,the FIRAGCM algorithm needs not to choose a step size,requires far less storage,and also has fast convergence.The IIRAGCM algorithm inherits all the advantages of the FIRAGCM one,and the convergence quality is greatly improved.Simulation results illustrate that the performances of the two algorithms are excellent.关键词：adaptive filtering;echo cancellation;FIRAGCM;IIRAGCM0|2|4更新时间：2025-07-02
- 摘要：Starting from the two most basic independent integral forms equations of field theory,the most general equation of loop current method in both non-linear and linear network could be deduced strictly and simply,meanwhile the general relation of self-complex impedance of a loop and mutual complex impedance between loops with complex electrical impedance,including the sign rule,was also given.关键词：non-linear network;loop current method;general equation;deduction by field theory0|2|1更新时间：2025-07-02
- 摘要：Associated with ITU-T recommendation G.983 about ATM based passive optical network (APON),a new frame structure and a medium access control (MAC) protocol are presented in this letter.The length of the frame is 125μs,which is very favorable to access STM(Synchronous transfer mode) services.For voice service,because it is sensitive to time delay and has very low bit rate,we adopt fixed bandwidth allocation.But for other services,we use dynamic bandwidth allocation.The CD (cell delay) and CDV (cell delay variation) characteristics of this MAC protocol are analyzed under several service scenarios through computer simulation.关键词：ATM based passive optical network;medium access control;cell delay;cell delay variation0|2|10更新时间：2025-07-02
- 摘要：We address the problem of computing a multipath,to transmit data over a computer network while ensuring given bandwidth requirement and/or end-to-end delay constraint.The proposed scheme combines advantages of single path routing and multiple paths routing.We consider four generic routing problems within the framework wherein the bandwidth can be reserved and guaranteed (once reserved),and propose polynomial-time approximate solutions.关键词：multiple paths;QoS (Quality of service) routing;bandwidth reservation0|2|6更新时间：2025-07-02
- 摘要：In this paper,a fuzzy control system based on genetic algorithms is presented under the background of applying electromagnetic light valve.The coding mode of its subject function,the fitness function and the selecting strategy of the fuzzy control system are analyzed.The Learning algorithm of optimizing control formula is given on the base mentioned above.Indicated by the experiments,the electromagnetic light valve based on adaptive fuzzy control has more superiority,and has applied in the 3DLCS.关键词：fuzzy control;genetic algorithms;electromagnetic light valve0|2|1更新时间：2025-07-02
- 摘要：Scalability is one most promising function which is required in MPEG-4 visual coding algorithm.In this document,sub-band/wavelet based scalable structures are proposed to support spatial scalability,temporal scalability and hybrid scalability.关键词：scalability;sub-band/wavelet decomposition;video object plane(VOP)0|2|5更新时间：2025-07-02
- 摘要：In this paer,a method constructing generalized ELGamal type blind signature schemes utilizing affine transform with two variables is developed.We show that among the 18 secure generalized ELGamal type schemes presented in [3] only twelve of them can be converted into strong blind signature schemes while the rest are weak ones.关键词：digital signature;blind digital signature;discrete logarithm0|2|1更新时间：2025-07-02
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