最新刊期
卷 39 ， 期 7 ， 2011
- 摘要：Considering the serious Inter-Carrier Interference (ICI) in Orthogonal Frequency Division Multiplexing (OFDM) wireless systems with high frequency,a low complexity frequency-domain linear equalization algorithm based on pre-processing is proposed.The new algorithm first extracts a time-variant factor from every channel response.Consequently,one-dimensional filtering pre-processing in time-domain can be achieved at the receiver.As for the time-variant channel after time-variant factor extraction,Banded structure is used to approximate its frequency response matrix,which achieves low complexity frequency-domain linear equalization at the receiver.The analysis and simulation results show that,the proposed algorithm can reduce the complexity to 10% or less at the cost of 1-2dB performance,relative to MMSE algorithm;the proposed algorithm can obtain at least 5dB relative performance gain with the same complexity,compared to the existing low complexity algorithm which discards part channel information.关键词：OFDM;ICI;Linear Time-Variant (LTV) Channel;Frequency-domain Linear Equalization(FDLE);Pre-processing2|1072|0更新时间：2025-07-16
- 摘要：The effects of the platform swinging on HASP-CDMA system are analyzed to complete the study on the HAPS instability,the intercell and intracell interference factors caused by the platform swinging are defined,and the capacity algorithm of the HAPS-CDMA swinging model is given.Then a novel user access solution is presented,namely the mechanisms of the signals from the users in the edge of the center reference cell in the swinging direction received by both of the two adjacent base stations to avoid the "pingpong handover".From numerical results it is observed that the algorithms can balance the system capacity and the resource well,and improve the system performance significantly.关键词：HAPS(High Altitude Platform Stations);beam forming;platform swinging;system capacity;interference factor3|1349|1更新时间：2025-07-16
- 摘要：This paper proposes a kind of acquisition algorithm for Direct Sequence Spread Spectrum (DS-SS) signal,which can overcome the adverse impact of the non-coherent data modulation effectively.In the algorithm,the received signal is multiplied by its delay conjugate result to eliminate the impact of the data transition.Then the Fast Fourier Transform (FFT) is used to calculate the circular correlation to estimate the PN code phase.After that,we use the estimate result of the PN code phase to despread the received signal and get the estimate of the Doppler frequency,which is achieved by frequency spectrum analysis with FFT.Theoretical analysis and simulation results show that,compared with the traditional algorithms,the proposed algorithm is not sensitive with the moment the data transition occurs and it saves the acquisition time significantly.The algorithm proposed in this paper can be applied to capture high-speed non-coherent data modulated signals.关键词：non-coherent data modulation;fast Fourier transform (FFT);delay conjugate multiply;acquisition time;signal to noise ratio(SNR) loss2|1452|4更新时间：2025-07-16
- 摘要：We mainly study on the design of noncoherent space-time code based on Grassmannian with algebraic method.First of all,we present a new family of full-rate and full-diversity coherent space-time codes with arbitrary number of transmit antennas and coherent time.Then our noncoherent space-time codes can be built from the coherent space-time codes via a non linear map called exponential map.With the same number of transmit antennas,the new noncoherent space-time code have better performance than the present code.关键词：space-time code;Grassmann manifold;unitary matrix;exponential map;degree of freedom2|1296|1更新时间：2025-07-16
- 摘要：Blind equalization algorithms based on high order statistics (HOS) are suitable to single input single output (SISO) systems,but HOS algorithms need large amount of data and cannot meet the time-varying requirements in high-speed signal transmission systems and have not enough ability to detect blindly high-order quadrature amplitude modulation (QAM) signals.A novel cost function is constructed using support vector regression by structural risk minimization principle whose empiric risk is composed by the cost functions of constant modulus algorithm (CMA) and constellation match error (CME),and the epsilon-insensitive loss function is adopted,all of which transform the blind equalization problems of high-order QAM signals into solving an unconstrained optimization problem.Finally,64-QAM signal is used to simulate and analyze the performance of the novel algorithm and the results show that the burden of algorithm and the data requirements are superior to those existing HOS algorithms.关键词：wireless communication;blind equalization;SVR(support vector regression);QAM(quadrature amplitude modulation);CME(constellation match error)2|1555|7更新时间：2025-07-16
- 摘要：The linear canonical transform (LCT),which is a generalization of the Fourier transform and the fractional Fourier transform,has been used in many fields of optics and signal processing.The short-time Fourier transform (STFT) is a kind of linear Time-Frequency Representations (TFRs).Compared with many bilinear TFRs,the STFT does not have the cross-term problem.Because of this advantage,the STFT becomes an important time-frequency analysis tool.Starting with the LCT's definition and its properties,many useful relations between the LCT and the STFT have been derived.Based on these relations,we present a new time-frequency signal analysis method,which has no cross-terms problem.It can be used to realize interference suppression of chirp signals and separate components from a time-frequency signal.Finally the simulation results illustrate the validity of the proposed method.关键词：the linear canonical transform;the short-time Fourier transform;time-frequency analysis;interference suppression;signal separation2|2011|5更新时间：2025-07-16
- 摘要：Error-Correcting Output Codes as a unifying framework for studying the multiclass categorization problems can reduce them to multiple binary problems effectively,thus simplifying the problem.But when generating component classifiers,we usually need to face the contradiction between the diversity among the component classifiers and the consistency of learning between the component classifiers and the ensemble classifiers.We call this contradiction consistent-diverse balance problem.How to reduce the error ratio caused by the inconsistency under diversity big enough is the breakthrough of the balance problem.Using weighted decoding,we can reduce the classification error caused by the learning inconsistency through relearning for weight coefficient matrix.In the proposed algorithm,by using GA to learn the weight coefficient matrix and taking the final generalization error of the ensemble classifiers as the fitness function,we can get the weight coefficient matrix of which the error of the training samples is minimum.The experiments respectively on artificial data sets and UCI data sets have proved that the algorithm is better than others for the consistent-diverse balance problem.关键词：error-correcting output codes;multiclass categorization;weighed decoding;genetic algorithms2|1411|5更新时间：2025-07-16
- 摘要：In view of the characteristics of Wireless Mesh Network (WMN),this paper investigates the relationship between the ideal optimal density of replicas over the space and the popularity spatial distribution of the media segments together with the capacity and reliability of the nodes,and then proposes a reliability repairing based replication optimization algorithm.Accordingly,to timely and accurately understand the characteristics of the nodes at various locations,this paper proposes a reliability estimation algorithm base on analyzing the age distribution of media segments and nodes.Further on,an implementation of full-distributed lightweight replication strategy is presented.These estimation algorithms and caching strategies only employ the handy information without adding complex infrastructure or suffering too much overhead,not only maintain the WMN scalability and flexibility,but also take into account the computing power and resource constraints.关键词：wireless mesh;streaming media replication;online estimation2|1171|0更新时间：2025-07-16
- 摘要：Optimal eliminating cycles in Information flow of authorization policies is an important prerequisite to the success of migrating important information systems to multi-level security systems.This paper firstly proves it is a NP-hard problem,then presents optimization algorithm based on dynamic programming and approximate optimization algorithm based on genetic algorithm.Computational complexity analysis and experiments show that the former is fast to find the optimal solution in small-scale environment,the latter is effective to find the approximate optimal solution in large-scale environment.关键词：access control policy;information flow;cycle;NP-hard;dynamic programming;genetic algorithm2|1282|1更新时间：2025-07-16
- 摘要：Recurrent fuzzy neural networks,which is usually trained by gradient descent,have some inherent shortcomings such as inefficiency of training process,local minimum.In this paper,we proposed a novel fuzzy neural network based on Echo state network and TS fuzzy model,called fuzzy echo state network (FESN),which is a generality of both TS modal and ESN.FESNs consist of several fuzzy IF-THEN rules,each of which has a ESN as consequent part.We illustrate that FESNs have some interesting characteristics,such as better nonlinear mapping capacity,local feedback and stable learning,which results in that FESNs can deal with dynamics of nonlinear system.Furthermore,similar to the TS model and ESN,parameters of the FESNs can be determined by solving a linear regression problem,which dramatically reduce the computing burden of the training process.Experiments shows that FESN can effectively enhance the accuracy of modeling dynamical system at the expense of not using excessive additional time compared with TS model and ESN.关键词：echo state networks;reservoir;TS model;modeling dynamical system2|1396|4更新时间：2025-07-16
- 摘要：Because of large amount of stochastic and uncertain factors in semiconductor wafer fabrication (SWF),we often meet with all kinds of disruptions which make the former optimal scheduling scheme lose superiority.Considering the advantage of the fuzzy Petri-net (FPN) on the knowledge expression and logical reasoning,a releasing control policy for SWF based on FPN is proposed.According to the releasing FPN –reasoning model and the real-time data collected from the line,the control method can help to take the feasible releasing action to adopted to different conditions.With the releasing strategy,the throughput of the wafer fabrication can be maximized and the system can be optimized to a large extent.Finally,the effectiveness of this proposed method is confirmed by simulation.关键词：semiconductor wafer fabrication;releasing strategy;fuzzy Petri nets2|1284|4更新时间：2025-07-16
- 摘要：Distributed source coding (DSC) is applied to hyperspectral image compression due to its low complexity and error resilience.In the framework of typical scalar coset coding based distributed compression method (s-DSC),it is pointed out in this paper that the infinity-norm minimization should be the best criterion for prediction,and a sub-optimal prediction method based on search for L∞ minimum is proposed to approach the criterion.In addition,the compression scheme is extended to near-lossless compression.The experimental results show that the lossless compression bitrate of the proposed method is reduced by about 0.25bpp compared to s-DSC and the near-lossless compression outperforms JPEG-LS significantly.Owing to the advantages of low complexity,high performance and error resilience,the proposed method is quite suitable for onboard compression.关键词：hyperspectral images;lossless and near-lossless compression;distributed source coding;coset coding;prediction;infinity-norm2|1382|11更新时间：2025-07-16
- 摘要：This paper mainly focuses on the structure tensor based image modeling approaches,including partial differential equations (PDE) and variational functionals.A type of corner shock filter is designated based on measures of corner strength and the theory of level-set evolution to enhance the corner structures.The filtering behavior of structure tensor based anisotropic PDE's is subsequently analyzed based on the edge shock filter and our proposed corner shock filter.The analysis comes to the conclusion that,Weickert's anisotropic PDE corresponds to a kind of smoothing-enhancing,and corner-preserving filtering mechanism,while Tschumperlè's trace-based PDE is the reduced version of Weickert's PDE,corresponding to a kind of smoothing filtering scheme but not corner-preserving.With the above conclusion,conditions of corner- preservation are intuitively proposed for structure tensor based variational functionals.Finally,a kind of unified regularization PDE framework is proposed for different image applications.The filtering behavior on homogeneous regions,edge,and corner structures can be described by our unified framework more intuitively and efficiently.Experimental results on image magnification demonstrate the efficiency of the unified PDE framework.关键词：variational functional;partial differential equation (PDE);shock filtering;structure tensor;corner preserving;image interpolation2|1451|4更新时间：2025-07-16
- 摘要：A novel non-subsampled Contourlet transform denoising scheme based on the normal inverse Gaussian prior (NIG) and Bayesian estimation has been proposed.Normal inverse Gaussian model is used to describe the distributions of the image coefficients of each subband in non-subsampled Contourlet transform domain,corresponding threshold function is derived from the model using Bayesian maximum a posteriori probability estimation theory.This scheme achieves enhanced estimation results for images that are corrupted with additive Gaussian noise over a wide range of noise variance.The simulation results indicate that the proposed method can remove Gaussian white noise effectively,improve the peak signal-to-noise ratio of the image,and keep better visual result in edges information reservation as well.关键词：denoising;non-subsampled Contourlet transform;normal inverse Gaussian model;Bayesian estimation2|1749|9更新时间：2025-07-16
- 摘要：An new algorithm based on localized Multi-Channel active contour model is proposed for image segmentation.For the images with obvious texture,Gabor texture features are constituted multiple channels of active contour model together with image intensity information.Considering that intensity and texture characteristics are inconsistent in the interior and exterior of the evolution curve,localized energy idea is introduced,the minimum energy is calculated in the specific local area around each pixel on the evolution curve.Our model combined with the shape prior is used to segment the shadowed objects.The proposed algorithm is exemplified on various images objects and its superiority over state of the art variational segmentation techniques is demonstrated.关键词：image segmentation;active contour model;level set;Gabor filter2|1358|8更新时间：2025-07-16
- 摘要：In the stepped-frequency radar system,motion introduces additive high order phase terms,which results in distortion of range profile.The phase modulation effect is analyzed and a novel ISAR imaging method is proposed for uniformly accelerative target,which based on predesigned waveform and phase cancellation.The pulse repetition time is predesigned to eliminate the high order phase terms introduced by velocity of the target.Then the high order phase terms introduced by acceleration are removed by phase cancellation.For a uniformly accelerative target,the velocity and acceleration are not need to estimate in the proposed method,so the computation burden is greatly reduced.Simulations with synthetic data demonstrate the performance of the new method.The results confirm its effectiveness.关键词：inverse synthetic aperture radar (ISAR);phase cancellation;stepped frequency waveform;motion compensation2|1364|1更新时间：2025-07-16
- 摘要：As the two most common forms of interference in synthetic aperture radar (SAR).Narrow-band interference (NBI) and wide-band interference (WBI) significantly reduce the quality of SAR images.Based on the analysis of the time-frequency concentration of NBI and WBI,an interference suppression algorithm for SAR is proposed.In the algorithm,SAR echo data is transformed into the short time Fourier transform spectrum domain,and then it is transformed into the wavelet domain.In the wavelet domain,the constant false alarm rate (CFAR) algorithm is employed to operate interference identification and suppression.After that,a clear and noninterference SAR image can be obtained by using a conventional SAR imaging algorithm.This algorithm brings less loss to useful data during interference suppression,and can efficiently suppress the time-varying NBI and WBI.The processing results of the simulation and the real measured data prove the effectiveness of this alaorithm.关键词：synthetic aperture radar (SAR);narrow-band interference (NBI);wide-band interference (WBI);interference suppression;wavelet transform (WT);short time Fourier transform (STFT)2|1470|4更新时间：2025-07-16
- 摘要：The measure of track correlation uncertainty was defined and was compared with the Shannon entropy measure and Hartley measure of information uncertainty.Then,the usage of track correlation uncertainty was expressed.Lastly,the requirements and a mathematic model for evaluating the track correlation uncertainty were proposed.Simulation results show that the track correlation uncertainty is measurable and can be correctly evaluated.The proposed evaluation method can quantitatively describe the effects of target separations,sensor measurement errors,correctness of track correlation,etc.to the track correlation uncertainty very well.Moreover,to the same input of correlation results,the proposed evaluating method can output almost the same evaluating results of track correlation uncertainty for the same correlated track pairs,no matter the sensors have systematic errors or not.关键词：multi-sensor;data fusion;uncertainty evaluation;track correlation3|1319|3更新时间：2025-07-16
- 摘要：We introduce a novel classification algorithm for gene expression data based on the Laplacian spectra of graphs.The class center is obtained by computing the average of each class in the traning set,and the Laplacian matrices of complete graphs so called normal graphs are constructed on some samples with the minimum Euclidean distance between the class center.The sum of matched points are calculated by replacing points of standard image with test samples.The test sample is divided into the biggest one of the total matched points of the class.The effectiveness of this algorithm has been verified through the leaving-one experiments using Leukemia data and Colon cancer data.关键词：classification;gene expression data;laplace spectra3|1456|2更新时间：2025-07-16
- 摘要：Based on Fibonacci sequence,the article discusses a method of digital watermarking about anti-JPEG compression.The algorithm constructs the Fibonacci quantification table Q of quantified DCT coefficients and the coefficient modification table M of embedded in the watermark by means of the Fibonacci sequence,Fibonacci integer sequences,as well as the rabbit sequence S.It can be used to solve the conflict between image compression quality and the robustness of watermarking by changing the threshold value N of constructed M table.As the Fibonacci number increases progressively in the form of the golden section and the main principle of the JPEG compression is DCT transform,this algorithm has a very good robustness for anti-JPEG compression through constructed quantification table and the coefficient modified table to modify the DCT of DC component embed the watermark.The experimental results showed that when the threshold value of structured M table N=7,the image compression quality IQ=40%,and the correct rate of the watermark extraction using the algorithm can reach more than 90%.关键词：Fibonacci sequence;watermarking;rabbit sequence;DCT (discrete cosine transform)2|1281|2更新时间：2025-07-16
- 摘要：Designing MDS matrices is one of the most important methods to construct diffusion layer for block ciphers,and Cauchy matrices generated by ordered-array is a basic kind of MDS matrices.This paper provides the necessary and sufficient condition of two distinct ordered-arrays generating one same Cauchy matrix.We show the count value of Cauchy matrices over finite field,and predicate that a Cauchy matrix could never be a cyclic-shift matrix.Further,this paper provides the necessary and sufficient condition of Cauchy matrices with minimum number of entries,and supplies the construct method of Cauchy matrix with minimum number of entries and maximum number of occurrences of 1.Additionally,this paper provides a construction for involution Cauchy matrices.关键词：block cipher;diffusion layer;MDS(maximum distance separable) matrices;Cauchy matrices;involution matrices2|1306|1更新时间：2025-07-16
- 摘要：CLEFIA is a block cipher proposed in FSE (Fast Software Encryption) 2007 by SONY Corporation.Some 5-round distinguishers of CLEFIA are presented according to study an equivalent structure of CLEFIA.Based on the 5-round distinguishers,some meet-in-the-middle attacks can be made on 6/7/8-round CLEFIA.The attack complexities are low enough and the key of 6/7-round CLEFIA can be recovered within one second in the ordinary PC.Moreover,the 8-round attack can be also implemented in the high-performance computer.关键词：block cipher;CLEFIA;meet-in-the-middle attack;real-world attack2|1306|5更新时间：2025-07-16
- 摘要：Idea Functionality is the core and basic unit of Universally Composable (UC) security protocols.The first step of designing the protocols,within the UCsecurity framework,is to extract an ideal functionality from the expected functionalities of the protocols.To appropriately define an ideal functionality we should not only protect the security of the definition,but also consider the realizability.This study investigates the security of identity-based signature (IBS) within the UCframework,defines a realizable identity-based signature functionality FIBS,proves that UC-secure IBS is equivalent to conventionally-secure (EUF-CMIA -secure) IBS.As a result,we are able to make sure that the EUF-CMIA scheme can be a module in designing a complex protocol that satisfies the UCrequirement.关键词：universally composable (UC) security;ideal functionality;identity-based signature(IBS);existential unforgery for adaptive chose-message and identity attack (EUF-CMIA)2|1751|5更新时间：2025-07-16
- 摘要：An efficient approach of member revocation in group signature is verifier-local revocation.In this approach,revocation messages are only sent to signature verifiers,while signers have no involvement.However,mostly provably secure group signature relied on the random oracle model that are out of reach in the real world,the designing of provably secure group signature in the standard model is also a hot topic of research in modern cryptography.Based on Boyen-Waters group signature scheme,we propose a group signature scheme with verifier-local revocation,which is proven to be secure in the standard model.The performance of the proposed scheme is analyzed;under the condition of 80-bit AES,our scheme is superior to the existing verifier-local revocation group signatures in the standard model both in the number of signature elements and the length of signature.关键词：group signature;verifier-local revocation;random oracle model;standard model2|1753|6更新时间：2025-07-16
- 摘要：We give a new labeling algorithm for sliding windows--a fair adaptive labeling algorithm on congestion control mechanism.The algorithm approximately identifies TCP and UDP flows,moderately distinguishes labels,and avoids the impact of congestion control mechanism on fairness.Based on the fine-grained description and prediction of the network congestion problem,the paper presents the self-adaption of the ratio of yellow package infused by each flow,and gives consideration to the impact on fairness caused by the state of network congestion.Compared with other labeling algorithms of sliding window,simulation experiment results show that FCA-ItswTCM has better effects on ensuring fairness between TCP and UDP flows and raising resource utilization and system stabilization.关键词：DiffServ;labeling algorithm;fairness2|1205|1更新时间：2025-07-16
- 摘要：A selective Bayesian classifier based on change of class relevance influence (CCRI SBC) was proposed by introducing a regulator factor into an attribute selection method,namely maximum relevance and minimum redundancy (mRMR).The regulator factor was used to change the influence degree of class relevance on the attribute selection,which can avoid the existence of redundant attributes in mRMR.In addition,a Bayesian information criterion was used to determine the optimal number of attributes automatically,which can overcome the randomness of classification results that easily caused by the setting number of attributes manually.In order to further make the CCRI SBC is applicable for continuous data,a discretization method,i.e.,equal frequency class attribute interdependent maximization was proposed,which has advantages of high classification correct rate and short discretization time.Experimental results on UCI datasets show that the proposed method can deal with the classification problem for discrete or continuous and high-dimensional data effectively.关键词：selective Bayesian classifier;attribute selection;maximum relevance and minimum redundancy;Bayesian information criterion;discretization2|1208|5更新时间：2025-07-16
- 摘要：A two-norm annular margin classifier is put forward based on two-norm cost function.The classifier defines a margin between two categories of training data with super sphere-structure and maximizes the margin.Experiment shows that the two-norm annular margin classifier improves the effects of classification for both balance and non-balance problems.关键词：pattern classification;support vector data description;two-norm cost function;annular margin2|1147|0更新时间：2025-07-16
- 摘要：Simulation is the major technique used for processor verification.In the late of the verification process,simulation requires a lot of expert time and computer resources to verify residual complicated functional points,which slows down the verification progress.This paper introduces a test generation method based on model checking engine to address this problem.First,an abstract microprocessor model focuses on these uncovered functional points is constructed using local modeling strategy.Second,model checker reads this abstract model and automatically produces test generator directives.Finally,these directives guide random test generator to generate test programs that cover the specified functional points.Experiments on verifying PKUnity UniCore32 microprocessor demonstrated that this method spent little time to cover these uncovered coverage tasks and increased the verification efficiency.关键词：functional verification;model checking;local modeling;test program generation2|1273|2更新时间：2025-07-16
- 摘要：The lower bound to the equivalent variational capacitance of a coaxial step discontinuity was solved with Functional Approximation Methods;the identity between the upper bound and lower bound to the equivalent networks' variational capacitances was proved for several common coaxial discontinuities,basing upon the identity essence of the upper bound and lower bound to the variational capacitance was obtained from the standpoint of eigen mode function.2|1109|0更新时间：2025-07-16
- 摘要：Compressive Sensing(CS) is a new developed theoretical framework for information acquisition and processing,which is based on matrix analysis,statistical probability theory,topological geometry,optimization and opsearch,functional analysis and so on.The high-dimensional signals can be recovered from the low-dimensional and sub-Nyquist sampling data based on the compressibility of signals.It not only inspires us to survey the linear problem again,but also enriches the optimization approaches for signal recovery to promote the combination of mathematics with engineering application.Nowadays the researches on compressive sensing have developed from the earlier concept understanding,numerical simulation,principle verification,and primary system designation,to the deeper researches on theory,development and application of practical system.In this paper,we introduce the basic idea of compressive sensing,and the development history,current and future challenges.关键词：compressive sensing;sparse representation;compressive measurement;optimization recovery77|13678|186更新时间：2025-07-16
- 摘要：In wireless communications,efficient power allocation has the advantage of reducing resource consumption,achieving better quality-of-service (QoS),and reducing network interference.This paper is focus on the power allocation problem in wireless parallel amplify-and-forward relay transmissions.Particularly,the objective is set to minimize the transmit power of the communication nodes while guaranteeing the signal-to-noise ratio (SNR) requirement at the destination node.Firstly,based on the established channel model of wireless relay cooperative communication system,the expression of SNR is derived.Following that,the power allocation problem is modeled as a combinatorial optimization problem.Moreover,using convex optimization theory,this paper proposes a suboptimal power allocation algorithm with low complexity.The simulation results show that the method proposed in this paper is capable of resolving the power allocation problem in wireless relay communication systems with low computational complexity as well as stable performance.关键词：wireless communications;relay;power allocation;amplify-and-forward;signal-to-noise ratio2|1271|4更新时间：2025-07-16
- 摘要：In order to guarantee quality of service (QoS) of different priority bursts and solve the problem of deflection control of deflection algorithm in OBS networks,a deflection routing algorithm based on priority and parameter-tunable in OBS networks is proposed.It intercalates the definition of a tunable-parameter (deflection probability) to control the deflection of contending bursts,and searches the optimum deflection path in terms of the burst loss probability and the deflection path length.When competition occurs,low priority bursts are segmented,and the segmentation part of bursts are deflected to free links.The algorithm selects many candidate routes which the tunable-burst loss probability of the first k priority burst and overall bursts in the deflection path is the least.At last,it chooses the shortest deflection path.Simulations show that the algorithm can reduce the burst loss probability of entire networks and protect the integrity of some high priority bursts.It also can efficiently reduce the delay,and reduce the offset time deficit on QoS guarantee.So the scheme can improve the performance of OBS networks.关键词：Optical Burst Switching (OBS);deflection routing;priority;parameter-tunable;quality of service (QoS)2|1396|3更新时间：2025-07-16
- 摘要：Robustness is divided into connectivity robustness and recovery robustness according to connectivity and recovery.Then we divide connectivity robustness into random-fault robustness and hostile-attacks robustness,and divide recovery robustness into node recovery robustness and edge recovery robustness according to type of network failure,besides we define the concepts of connectivity robustness and recovery robustness.Then these concepts are used to evaluate the degree of robustness of Bernoulli node model,and the conclusion is achieved that the hostile-attacks robustness of hierarchy structure is less robust than planar structure while the random-fault robustness is more robust than planar structure,and that the node recovery robustness of hierarchy structure is more robust than planar structure while edge recovery robustness is less robust than planar structure.关键词：wireless network;connectivity robustness;recovery robustness;Bernoulli node model2|1430|1更新时间：2025-07-16
- 摘要：The opportunistic spectrum access (OSA) techniques in the ad hoc network are researched in this paper.An access scheme is proposed,which can not only suppress the interference between the secondary and the primary users,but also realize the fair and non-conflict resource sharing among secondary users.The solved problems include the spectrum sharing,and the optimal channel selection for secondary users which assure both the interference suppression and the self-optimization.For these purposes,the double selection scheme is built between the secondary users and the available channels.Factors to select channels for secondary users are defined based on the channel available degree.So,the secondary users can select the most appropriate channel according to the service and transfer characteristics.The results prove that the double selection scheme can avoid the conflict and realize the efficient resource sharing.关键词：opportunistic spectrum access;MAC protocol;cross-layer design;spectrum sharing;Ad Hoc network3|1891|0更新时间：2025-07-16
- 摘要：NC (Network Coding) provides an interesting approach to WPRTPs (Wireless Packet ReTransmission Problems) in wireless networks.Existing researches are mostly focused on P-WPRTPs (Perfect WPRTPs) where,for one receiver,a packet is either being requested by or already known to it.Contrastively,no previous efforts focus on IP-WPRTPs (ImPerfect WPRTPs) where,for one receiver,a packet can be neither being requested by nor already known to it.In this paper,we focus on IP-WPRTPs.WPRTP reduction theorem for simplifying WPRTPs is proposed and proved at First.Then,the upper and lower bounds of the number of packet transmissions in optimal linear NC-based solutions to IP-WPRTPs are analyzed.Next,a scheme named as IP-WPRTP-DC (Divide and Conquer based scheme for IP-WPRTPs) is proposed based on WPRTP reduction theorem using a divide and conquer approach.Extensive simulations showed that IP-WPRTP-DC is more effective in saving the number of packet transmissions for solving IP-WPRTPs than traditional schemes not using network coding.关键词：imperfect wireless packet retransmission problems;divide-and-conquer based scheme;problem reduction;optimal scheme;random network coding2|1186|0更新时间：2025-07-16
- 摘要：Now a large number of intermediate nodes face a fact of using drop tail queue management,therefore a random back-off TCP congestion control algorithm named TCP Njust is proposed.When congestion occurs,randomly reduce the congestion window within a certain range,but when congestion avoid,congestion window is randomly increased within certain limits to reduce TCP global synchronization.This algorithm requires a random function on the base of Newreno.Simulation results show that this algorithm performs better than Newreno,and also better than Vegas when a large number of burst data stream occurs in the network,and it's suitable for use in the internet.关键词：network congestion control;global synchronization;random back-off;congestion window;drop tail2|1321|2更新时间：2025-07-16
- 摘要：The standard wavelet transform fails to provide an efficient representation due to the spatial isotropy of its basis functions built in the horizontal and vertical directions.In this paper,Directionlet based compression scheme was proposed .Using improved octree segmentation to adaptively partition an image into the smaller segments with a dominant direction.Directionlet is applied on a geometrical regular segment,whose optimal geometrical directions constitute the generator matrix of Directionlet transform,coding the coefficients and directional information respectively.Application of Directionlet transform along the optimal geometrical direction per segment efficiently improves sparse representation for image and enhances the coder performance.Experiments demonstrate the superiority of the proposed approach when compared to the wavelet-based SPIHT and JPEG2000 both in terms of objective compression performance measurements as well as visual quality,especially for those images with geometrical regular features.关键词：image compression;directionlet transform;optimal geometrical direction;geometrical regular image2|1478|1更新时间：2025-07-16
- 摘要：The definitions of the edge density and the segment complexity are given,and a novel algorithm for recognition of bridge without water under it in remote sensing image is proposed.Firstly,the edge is extracted with Canny operator,and the edge density for each pixel is calculated.The image is segmented base on the edge density.Secondly,the suspected bridge area is identified by a series of processing including using Hough transform to extract straight line and calculating segment complexity.Then texture features of the suspected bridge area are extracted to form a feature vector.Finally,each suspected bridge is classified by Back Propagation Neural Network(BPNN) based on this feature vector.The experimental results show that the algorithm can perform well to detect bridge targets.关键词：target recognition;edge density;segment complexity;texture features;BPNN2|1291|6更新时间：2025-07-16
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Nonmonotone Total Variation Minimization Based Projection Restoration for Low-Dose CT Reconstruction
摘要：In order to improve the reconstruction quality of low-dose CT image,a new approach is proposed based on low-dose CT projection restoration in this paper.First,projection data is transformed from Poisson distribution to Gaussian distribution using nonlinear Anscombe transform.Then,the Anscombe transformed data is filtered by an efficient nonmonotone total variation minimization denoising algorithm.Last,the reconstruction is achieved by inverse Anscombe transform and filtered back projection (FBP) method.Simulated and clinical low-dose CT data experimental results demonstrate that a high-quality CT image can be reconstructed.关键词：low-dose CT;nonmonotone total variation;Anscombe transform;projection restoration2|1578|7更新时间：2025-07-16 - 摘要：The scattering phenomenon has an important influence on the reconstructed image in Cone Beam CT (CBCT) imaging systems,and is a hot research on CBCT all the time.Aiming at the scatter artifact in the cone beam CT system,we proposed a new scatter correction method that needed to add an attenuation baffle between the X-ray source and the tested object.This study is based on the Klein-Nishina formulas and Beer theorem.Through subtracting the scatter distribution image from the original projection image,we can acquire the scatter corrected projection Images of the tested object.The result showed that the method can effectively increase the image contrast and increase the quality of the reconstructed slice image.关键词：scatter correction;Compton scatter;attenuation baffle2|1495|6更新时间：2025-07-16
- 摘要：This paper studies on the cone target.Firstly,the modulating function of a precession target on the radar is analyzed.Then,the decomposition method of multi-component sinusoidal frequency modulated signal based on empirical mode decomposition (EMD) is studied.The instantaneous frequency of each intrinsic mode function is gained by using Short Time Fourier Transform (STFT).The precession features of precession period,precession angle,micro-motion range ratio of different scatters and geometry feature of aspect ratio are extracted.Finally,the results of feature extraction by utilizing the darkroom measurement are shown in figures,which validate the ideas.关键词：micro-motion feature extraction;cone target;empirical mode decomposition;instantaneous frequency2|1518|15更新时间：2025-07-16
- 摘要：When acquiring GPS signal,signal strength and noise level is time varying in the environments,indoor,in urban street or in the woods.In the challenging environments,adaptive scheme is considered to be employed in GPS receiver design in this paper.Derived from conventional adaptive structure,a novel method of noise level estimation is proposed which fully considers the characteristic of GPS signal.Furthermore,possible large Doppler shift is seldom considered in existing adaptive structure.Aiming at the possible Doppler shift,a solution based on partial correlation is proposed.In the final part of this paper,simulation is carried out to test this novel structure.The experimental results of the proposed method demonstrate more stable acquisition performance than conventional ones.关键词：constant false alarm rate;GPS signal acquisition;adaptive structure2|1203|2更新时间：2025-07-16
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