最新刊期
卷 ， 期 1 ， 1999
- 摘要：In this paper,an edge detector based on a B spline smoothing formula of image is proposed.Firstly,a smoothing surface with perfect information of the digital image is presented by using the uniform B spline function.Since the B spline is a locally supported function,the smoothing formula can be strictly limited in some neighborhood of a point,i.e., S（x,y）=∑（i,j）∈N k,l （x,y）f（i,j）Ω k（x-i）Ω l（y-j） The surface is smooth,and it has the same convexity as that of the original image.secondly,the edge point is detected by either computing the local extreme of the directional derivative or computing zero crossing of the second order directional derivative of the smoothing surface.Finally,and example of the detector performance is given.The numerical experiment suggests that our detection scheme may be used in computer vision,such as feature extraction,segmentation of image,and texture synthesis.关键词：edge detection;feature extraction;computer vision;Smoothing splines5|191|36更新时间：2025-12-08
- 摘要：In the paper the speech recognition system is developed based on private automatic branch exchange（PABX）.This system can recognize speaker independent continue speech commands over telephone channel based on medium and small vocabulary（<1000 words）.Statistics of the different sentence pattern of speech commands has been done and the corresponding recognition networks has been established.The system uses enhancive training combined with a embedded composite model which concatenate the sub word models,and improved token passing Viterbi algorithm,which improve the recognition accurate of the system.In the paper recognition accurate are compared according to different speech characteristic parameters and the state numbers of Hidden Markov Model.The rejecting recognition algorithm are studied.The recognition accurate is over 88% without rejection and over 95% with 20%rejection of utterances.关键词：speech recognition;Hidden Markov model （HMM）2|123|11更新时间：2025-12-08
- 摘要：Accuracy,continuity and stability are the main problems in speech pitch analysis.In this paper,a new Mandarin pitch contour estimation methodlogy is proposed.First,AMDF is substituted by LVAMDF （Length Varied AMDF）for higher accuracy and better time resolution.Second,the concept of Vowel Clarity is introduced according to the characteristics of Mandarin speech signals.Based on LVAMDF and Vowel Clarity,a series of methodologies are developed,including Vowel Center Location,Multi period to Single period Pitch Adjustment,Pitch Neighborhood Searching,etc.,which has gained much higher accuracy,continuity and stability than standard Mandarin pitch estimation methods.关键词：Pitch estimation;Mandarin pitch estimation2|252|46更新时间：2025-12-08
- 摘要：Based on the waveform of linear prediction residual（LPR） within a pitch period,a simple and effective approach of variable dimension vector quantization （VDVQ） of LPR spectrum is proposed.The shape vector of spectral magnitude of LPR is vector quantized by using the universal codebook having fixed dimension.The combination of the universal codebook and structured VQ reduces storage and computational complexity,delivers a high quantization efficiency and enhances the perceptual quality of the coded speech.The results of computer simulation have shown that a speech coder designed by using this VDVQ technique operating at 2400 bps led to a high synthesized speech quality.关键词：speech coding;linear prediction;Variable dimension vector quantization（VDVQ）2|78|13更新时间：2025-12-08
- 摘要：Based on semitransparent effect,direct volume rendering method can display the small and poorly defined features of the 3D dataset.But since all voxels participate in the generation of image,rendering time is long.The quality of surface based rendering image is not very good when the segmentation is not very accurate and the topology of the suface is complex.Presented here is a algorithm which absorbs the ideas of the two above method.Firstly,we choose the opacity mapping function carefully to enhance the effect of boundary on the final image.Secondly,rendering time is reduced since only the voxels in fuzzy surface participate in the rendering process and layer is used to visualizing the human brain cortex.Results show the algorithm is good enough to rendering the complex gyrus and sulci structure of the brain cortex.关键词：Medical visualization;Direct volume rendering;Fuzzy surface;Opacity mapping;Accelerated algorithm2|61|7更新时间：2025-12-08
- 摘要：A block feature matching algorithm using predictive search （BFMPS） algorithm that is used for motion estimation in such the international standards as H.261,H.263,MPEG1,MPEG2,and HDTV,is proposed in this paper.Based on the spatial characteristics of center biased distance between motion vector and corresponding prediction vector and temporal correlation of motion vectors,this method can significantly reduces the search times.The BFMPS method uses the simple and effective block feature matching function for block matching,and thus the corresponding complexity of block matching computation,data fetching,and memory management is greatly reduced.Simulation results show that the proposed BFMPS algorithm is efficient to reduce search times and computational complexity of motion estimation.Comparisons of BFMPS with other fast search algorithms are also given in detail.关键词：motion estimation;MPEG1;MPEG2;H.261;H.263;HDTV;video coding2|273|26更新时间：2025-12-08
- 摘要：This paper suggests an algorithm of multiresolutional Classified Vector Quantization for Image Coding,in according to the correlation among the various scales and different orientation bands after wavelet transformation.This algorithm rearranges the coefficients from various resolution level and orientation and gets a vector of 64 dimensions which then is classified and quantized.Meantime,we design an efficient classifier,and give the experiment results and data under different conditions.Compaered with other methods,it proved that the algorithm not only improves the image quality,but also decreases the computation complexity.关键词：wavelet transformation;Multiresolution;Classified vector quantization;Bits distribution;variance3|96|7更新时间：2025-12-08
- 摘要：We expounded that one given signal can be approximated in arbitrary accuracy by a finite sub family of a frame.And suggested an adaptive algorithm of representation for images based on nonorthogonal basis functions.The algorithm may efficiently represent the local features and the energy distribution.关键词：Basis functions;Frame;Adaptive representations;Gaussian function;Truncation operators2|101|2更新时间：2025-12-08
- 摘要：A array pairs and a autocorrelation functions of the array pairs are proposed,and the perfect binary array pairs are difined.The sizes,the transform characters and a class of the perferc binary array pairs are discussed,and the necessary condition for the perfect binary array pairs is given.The perfect binary array pairs for a small sizes are listed.关键词：information theory;Perfect binary arrays;array pairs;signal theory6|256|195更新时间：2025-12-08
- 摘要：In this paper,we propose a new VBR video model,a double first order autoregressive Gamma sequence with a three state Markov chain （2 GAR（1））.First,its characteristic of Gamma distribution can follow the bit rate of a VBR video source better.Second,the model’s coefficients determined by the autocorrelation function can explain the function’s behavior better.Third,the modeling of video source is accomplished using the three state Markov chain including the effects of scene change.We analyze the model in detail.Also,we give the methods to determine the parameters,and reach some important conclusions.关键词：ATM networks;VBR video service;Traffic modeling;Gamma distribution;Markov chain2|41|2更新时间：2025-12-08
- 摘要：Co channel transmission can dramatically increase channel capacity in wireless digital communication.In this paper,a recursive neural network is proposed for separating non ideal cochannel digital signals arriving at an antenna array.The received signals of the antenna array can be thought as the outputs of a linear mixing transmission system driven by N independent sources.Since the channels are not ideal,each element of the mixing array is a linear sub system instead of a constant.To recover the transmitted signals,the recursive neural network is used to realize signal separation and channel equalization.Learning algorithm of the neural network is presented and its stability is discussed.Simulation results demonstrate its good convergence property and anti noise performance in recovering both PAM and QAM signals.关键词：blind separation;Co channel digital signal;Non ideal channel;antenna array2|113|12更新时间：2025-12-08
- 摘要：In this paper a new expanded recycle dilated Banyan network（ERDBN）is proposed.Without input buffers,ERDBN can fully reuse the wasted capacity of pure dilated Banyan network and decrease the network complexity.We also discuss the out of sequence pheonomenon of ERDBN and present an algorithm to guarantee the cell sequence.An alalytical model of ERDBN and a study of network performance are presented.关键词：Telecommunication system;Switch;ATM;Banyan2|38|0更新时间：2025-12-08
- 摘要：The effects of three different ON OFF sources,periodic ON OFF,exponential ON OFF and Pareto ON OFF,on the performance of ABR services are studied and compared in this paper.A bigger buffer should be used to store the backlogged ABR cells accumulated during ON period of Pareto ON OFF sources.An algorithm is proposed to smooth the traffic flow of Pareto ON OFF sources and develop the performance of ABR services.The experimental results are explained by theoretical analysis.关键词：Pareto distribution;ON OFF sources;ABR services;ATM network2|59|10更新时间：2025-12-08
- 摘要：This paper presents spline time frequency method for processing signal with three frequency bands.The method can separate and process signal by frequency characters automatically.Equal theorem of optimal space and consistent theorem of approximate space are proved.Applying this method to process the measured tracking signal of trajective missile,we successfully separate true trajective,draft error and random error.关键词：signal processing;Time frequency analysis;Spline function;Non linear regressive model2|114|25更新时间：2025-12-08
- 摘要：The design problem of cosine modulated QMF banks satisfying the perfect reconstruction property has been formulated as a quadratic constrained least squares（QCLS）optimization problem whose constrained matrices are symmetric and positive definite.In order to efficiently solve this kind of QCLS optimization problems,we construct a cost function which is a convex function of our desired prototype filter coefficients.So a global minimum of this problem can be easily obtained.Results of two digital design examples are presented to support our derivatives and analyses in this paper.关键词：Cosine modulated quadrature mirror filter（CM QMF） banks;signal processing;Multirate signal processing;filter bank;global optimization;Penalty function approach（PFA）2|143|9更新时间：2025-12-08
- 摘要：By utilizing a hybrid self healing algorithm,the queue models are established for several typical implementation schemes of self healing function in VP switches.A large amount of computer simulations are made,and detailed analysis is presented to the effect of implementation schemes of self healing function and some architecture parameters in VP switches on self healing performance.The analytic results are useful to choose a reasonable implementation scheme of self healing function and architecture parameters in VP switches for the best self healing performance.关键词：ATM network;VP switch;Self healing algorithm2|21|0更新时间：2025-12-08
- 摘要：The Hamming correlation property of recently proposed chaotic frequency hopping sequences is not good enough.In this paper the authors present the construction of completely random hopping sequences by chaotic maps.The Hamming correlation is reduced significantly and is shown to be Poissondistributed.The system capacity of chaotic hopping sequences is almost identical to conventional hopping sequences in frequency hopping/code division multiple access（FH/CDMA） systems.关键词：chaos;Frequency hopping sequence;Hamming correlation function4|379|86更新时间：2025-12-08
- 摘要：In this paper,we propose the maximum likelihood sequence estimation of phase modulated diversity combining system without knowledge of channel parameter,together with a suboptimum modified Viterbi algorithm using this principle.The algorithm is applied to RAKE receiver without channel estimation,and the simulation results show near optimum performance for uncoded DQPSK and coded QPSK signals,which recovers the power loss due to differential reception.关键词：diversity;RAKE receiver;Viterbi algorithm2|90|1更新时间：2025-12-08
- 摘要：The characteristic of a new type of HF ALE modem,CHIRP modem is introduced first.Then the algorithm of soft decision decoding of Golay （24,12） used in this modem is discussed.We synthesized some techniques to design a fast and flexible scheme of soft decision decoding.The decoding time and coding gain of this scheme are tested under on HF channel simulator,and the result of test is satisactory.We also raised a new scheme to evaluate PBER,one of the most important we analyzed the characteristic of PBER evaluation according to the simulation results and discussed some schemes to improve the performance of PBER evaluation.关键词：Short wave;Automatic link establishment;Channel evaluation;soft decision;Pseudo bit error ratio2|109|3更新时间：2025-12-08
- 摘要：This paper presents an algorithmto observe frequency deviation （FD） for QAM signal reception.It can be used in an all degital receiver where the synchronizer no longer employs any PLL.This paper first presents the algorithm of the FD observer,and then introduces 1st order FD Kalman filtering algorithm,at last combines the FD observer and thd FD Kalman filter to form an FD estimator,which provides a practical solution for carrier synchronization in mobile communication channel.关键词：Frequency deviation observer;Frequency deviation estimation;carrier synchronization;Kalman filtering;All digital receiver2|793|82更新时间：2025-12-08
- 摘要：In this paper,we study capacity performance of Random Access Multi Code CDMA （RAMC CDMA） in Nakagami frequency selective multipath fading and nosy channels （MFNC）.The transmitters adopt BPSK modulation and the coherent RAKE receivers are assumed.Having built the system model,we analyze conditional probability distribution and average error probability of output.Also,in Rayleigh（one example of Nakagami） multipath channels,the numerical results of capacity are evaluated.It is proved that RAMC CDMA can transport higher bit rate services without extra bandwidth than general DS CDMA system,and the capacity is not too low.关键词：code division multiple access;Multi code code division multiple access;Media access control;multipath fading;Capacity of communication system2|75|1更新时间：2025-12-08
- 摘要：In this paper,a ranking based adaptive evolutionary operator genetic algorithm（RAOGA） is proposed.RAOGA uses ranking operator to rank the individuals according to their fitness value,and the probabilities of select operator,crossover operator,mutation operator are adapted to ranking value of the individual,in the meantime,the probability of select is adapted to evolving process.Then,we prove its performance of convergence to the global optimum by means of Markov chain analysis.At last,the experimental result shows that the RAOGA converges to the global optimum more rapidly than that of the conventional genetic algorithms.关键词：genetic algorithm;evolution;adaptation;neural network2|305|40更新时间：2025-12-08
- 摘要：In this paper,we propose zero padding as a boundary processing method for orthogonal wavelet transform with compact support.The perfect reconstruction of zero padding is proved and a perfect reconstruction algorithm is suggested;Zero padding method is compared with several other boundary processing methods and three advantages are pointed out:（1）perfect reconstruction of boundaries;（2）construction simplicity of perfect reconstruction sythesis filter bank;（3）good performance of the filter bank on boundaries.关键词：orthogonal wavelet transform;Boundary processing;Zero padding;Perfect reconstruction2|168|14更新时间：2025-12-08
- 摘要：This paper,by means of a new method,the graph theory,reanalyses the stability of antisymmetric discrete Hopfield networks,avoiding the construction of energy function.The nessesary and sufficient conditions for a network to converge to a cycle of length 4 are presented,and the number of cycles of length 4 associated with a p order antisymmetric discrete Hopfield network is discussed,with some suspicions presented.关键词：Discrete Hopfield Network;State graph of the network;Antisymmetry;stability2|97|19更新时间：2025-12-08
- 摘要：User identification and message authentication are two important aspects of network security.In this paper we discuss the identification and authentication schemes and techniques.User authentication schemes and message authentication schemes are the two main themes being introduced and discussed in our survey.Furthermore,advantages and disadvantages of some schemes are also analyzed.关键词：information security;User Authentication;Message Authentication4|859|320更新时间：2025-12-08
- 摘要：In this paper,a speech subband coding system combined with time domain harmonic scaling algorithm has been studied.The filter banks used for splitting subband are designed by employing orthogonal and biothogonal wavelet transform,which are similar to discrimination property of human auditory.Moreover,we provide several quantization techniques at different bands.Our goal is to raise the compression ratio of speech greatly degree while preserves good objective decoding SNR and subjective qualities of reconstucted speech.关键词：Speech compression coding;subband coding;Wavelet filter bankes2|192|9更新时间：2025-12-08
- 摘要：In this paper,after briefly introducing wavelet transform,the theory of the edge detection by using wavelet transform is presented.A method of the edge detetion by using 3 spline wavelet is presented.Finally,some examples are given to demonstrate the effectiveness of the method.关键词：wavelet transform;Multiresolution;Local maximum;Image edges2|405|54更新时间：2025-12-08
- 摘要：This paper presents a new flow control scheme for ATM WANs using fuzzy predictions.The scheme mainly contains two parts:traffic prediction and bandwidth allocation.A set of inference rules and associated membership functions are developed.In bandwidth allocation,we incorporate SER mechanism proposed by the same author ,which guarantees allocation fairness and utilization efficiency.We study the flow control scheme with an ATM network in the presence of rt VBR traffic.关键词：ATM;ABR Flow control;fuzzy logic2|78|16更新时间：2025-12-08
- 摘要：This paper has presented a scalar vector quantizer（SVQ） shaping method across then subchannels using region partition in the DMT modulation system,analyzed and simulated its performance.关键词：DMT modulation;SVQ Shaping;shaping gain;Continuous approximation2|38|0更新时间：2025-12-08
- 摘要：A novel method based on phase quantization is proposed in this paper to do timing synthesis such as timing recovery and jitter synthesis.The optimal performance can be achieved by Viterbi algorithm.Some practical implements of reduced complexity,namely T Viterbi and two order Sigma Delta Modulations（SDM）,are also explored.The simulation results show that the quantization error is much less than conventional simple SDM.We also use this method in jitter generation,which show great advantages.关键词：SDM;Viterbi;Timing synthesis;Phase quantization2|44|1更新时间：2025-12-08
- 摘要：Linear Diversity Transform（LDRT） is an efficient anti fading technique which was presented recently.In this paper,the performance of LDRT over rician fading channel is studied.When modulation scheme is QPSK,the results of computer simulation show that under the condition that BER（Bit Error Rate） equals to 10 -4 ,LDRT gain can approximate 21dB when K is 0dB;the gain of LDRT would decrease as K increases;the performance of LDRT is 1dB worse than the one of Guassian Channel when K equals to 10dB.The impact of the LDRT matrix order L over the system performance is also discussed.关键词：LDRT;Rician fading channel;BER2|83|0更新时间：2025-12-08
- 摘要：This paper proposes a bandwidth allocation scheme and performance analysis method based on real time guaranteeing probability with LTPB network.The guaranteeing probability has been derived in an exact expression and an applicable approximate closed form expression.关键词：Linear token passing bus;Real time system;bandwidth allocation;Real time guarantee probability2|86|1更新时间：2025-12-08
- 摘要：A 1200/2400bps full duplex modified vocoder based on the multi band excitation（MBE） speech model is presented.It has been used in many communication systems.Diagnostic Rhyme Test（DRT） results show that the speech distinctness at 1200bps and at 2400bps is 91.75 and 92.67 respectively.This paper focuses on the hardware architecture and algorithm implementation.关键词：Multi band Excitation;Vocoder2|128|7更新时间：2025-12-08
- 摘要：The problem of minimal cost routing （MCR） for PSTN/ISDN based video conference networks is addressed in this paper.Even though MCR can be viewed as a special case of well known SPN（Steiner Problem in Networks）,it is still an NP C hard problem.Heuristics algorithm is expected in order to solve the problem in realtime for most of practical applications.One of such algorithms named NJTU algorithm is proposed,which is a modification of the known SPN heuristics algorithms.The performance of NJTU algorithm is evaluated by 28 randomly chosen sample cases.The difference between the results calculated by NJTU algorithm and the optimal solution is minor.Based on the analysis of the algorithm,a routing table method is proposed as well for the applications which has more limited computation capability and/or needs much shorter response time.关键词：SPN;routing;Video conference2|21|0更新时间：2025-12-08
- 摘要：By using the properties of dual distance distribution,the necessary condition ofis proved to be also sufficient for δ =1.Moreover,we have that for （ n,2,ω ）code,being proper is equivalent to being good.Finally,bounds of undetected error probability for （n,2,ω） code are obtained.关键词：Binary nonlinear constant weight code;Undetected error probability;dual distance distribution2|41|2更新时间：2025-12-08
- 摘要：The theoretical throughput of the S ALOHA system is 36%,but meanwhile there’s a large average delay in the system due to frequent retransmission.So it does not fit for the condition that needs real time services.The paper finds that a random access system based on CDMA techniques can achieve the same throughput as ALOHA system,while has a reduced average delay.And with some anti inference methods of CDMA technique,the system performance can be improved.Some numerical results are given.关键词：Aloha;CDMA;Throughput;delay2|157|2更新时间：2025-12-08
- 摘要：This paper discusses the problem on construction of classification hyperplane in hidden space for feedforward neural networks.This problem directly corresponds to the design of the connection weights from hidden to output neurons.The research result shows that the connection weights from hidden neurons to the output neuron can all be +1,and the bias of the output neuron can take only a basic bias of 12 plus an integer in a limited integer range as an auxiliary bias.This results that the hidden to output connection weights and bias do not need to train,which decreases the searching space of network parameters during the training process of the networks,and it is much easier for the hardware realization of the network as there is no need for multiplicator,and the network constructed in this way is somewhat robust to the input data.关键词：Feedforward neural network;Classification hyperplane;Connection weight;Bias of a neuron2|45|10更新时间：2025-12-08
- 摘要：In this paper,we generate binary spreading sequences for DS/CDMA by the Logistic map.The even correlation and odd correlation of such sequences of length N are all Gaussian distributed,with mean 0 and variance N .The system capacity of chaotic spreading sequences is shown to be identical to conventional sequences in CDMA sytems.关键词：chaos;Spreading sequence;Logisic map2|278|70更新时间：2025-12-08
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