最新刊期
卷 44 ， 期 2 ， 2016
- 摘要：As more and more execution units are integrated in the digital signal processor(DSP) with single instruction multiple data stream(SIMD) extension, the flexibility and bandwidth efficiency of parallel memory access have significant effects on its whole practical performance.Based on detailed analysis of the memory access problems for radix-2 fast Fourier transform(FFT) algorithm in general SIMD DSP, this paper used parts of the address bit XOR logic to realize memory access address translation, and achieved conflict-free parallel SIMD memory accesses for FFT computation.Then several memory access instructions with special shuffle modes were brought forward, which could completely eliminate extra shuffling instruction operations of radix-2 FFT algorithm in the SIMD architecture.Finally, the vector memory(VM) in 16-way SIMD DSP YHFT-Matrix2 was optimized by above methods.The test results show that the optimized VM can realize fully pipelined conflict-free memory accesses and 100% parallel memory access bandwidth utilization with increase of 18% area overheads.Compared with the design before optimization, the performance of different points radix-2 FFT can achieve speedup ranging from 1.32 to 2.66.关键词：FFT;SIMD;low-order interleave;parallel memory;access conflict;data shuffle480|1278|2更新时间：2025-07-16
- 摘要：With the development of the Internet of Things (IoT), it accelerates the process of the informatization of all industries.Information service is an important service in the IoT.However, massive and heterogeneous data of the IoT brings the storage huge challenges to the information service.This paper proposes an IoT information service system to solve the current problem of the performance shortfalls and the difficulty of data sharing, which is based on NoSQL, REST and NIOT (National IOT id management and public service platform).The work focuses on improving the performance of the system and exploring the expression of storage and the sharing mechanism of the heterogeneous data.The test result shows that the solution proposed by this paper significantly enhanced the system performance.The relevant achievements of this paper provide reference for facilitating the development of the IoT information service system.关键词：Internet of Things;massive and heterogeneous data;information service system;data storage;data sharing3|3170|9更新时间：2025-07-16
- 摘要：Trustworthy service composition in service-oriented mobile social networks suffers from the opaque characteristics of service components, the subjective interpretation of trust requirements, and the opportunistic connectivity of social participants.To tackle these issues, we propose a trust-based decentralized service-composition approach.The proposed approach decentralizedly evaluates the trustworthiness of target services at both component and composite levels based on a lattice-based trust model to prevent data from being transmitted to untrustworthy counterparts.Moreover, by analyzing the dependency relationships, service are selected satisfied both global and local constraints specified by service consumers and vendors respectively.Finally, based on Monte Carlo method, a trustworthy social path selection, optimization and fault-tolerant approach is developed to deliver service evaluation and invocation information.Experimental results demonstrate its practical suitability of service composition for service-oriented mobile social networks, which leads to low cost for service evaluation, as well as high success rate and aggregated trust value for path selection.关键词：trust;decentralized service evaluation;path selection;service composition;service-oriented mobile social networks2|1628|7更新时间：2025-07-16
- 摘要：Relay system can improve the secrecy of a wireless communication with physical layer security algorithms.Most of these algorithms include two stages:during the first stage, the source node sends coded messages to the relays, and during the second stage, the relays forward the received messages to the destination node.Usually, there is no protection during the first stage, thus most of the secrecy analysis is based on the assumption that there is no direct channel between the source and the eavesdropper.In a practical system, when the eavesdropper is located near the source, the secrecy rate of all these algorithms is down to zero.In this paper, a novel three-stage algorithm with hybrid signals is proposed, which can offer full protection on a relay system.The algorithm results in a non-convex optimal problem, and a sub-optimal solution with low computational complexity is proposed.The theoretical analysis and simulation results show that the proposed scheme can achieve much better secrecy performance than traditional algorithms when the eavesdropper is near the source node.关键词：wireless communication;physical layer security;relay network3|956|5更新时间：2025-07-16
- 摘要：To solve the dilemma that a high bit generation rate and a low probability of bit disagreement can't be achieved simultaneously in current physical layer key extraction schemes, a high-speed random key extraction scheme based on vector quantization (HRVQ) which just employs the RSS of Wi-Fi signal is proposed.First, the inconsistent RSS measurements between the two communication parties were reduced by inconsistency removal to achieve low bit disagreement rate.Then, the vector quantization was introduced to accelerate the extraction of bit streams from channel information and achieve high bit generation rate.Last, fuzzy extractor was employed to achieve adequate randomness and zero bit disagreement rate.The result of experiments indicates that our scheme outperforming the best scheme of the state-of-the-art can reach a 284% bit generation rate with a zero bit disagreement rate and a guaranteed randomness.关键词：physical layer security;information theory security;key extraction;vector quantization;fuzzy extractor3|1113|2更新时间：2025-07-16
- 摘要：Based on multi-objective optimization, a service access control algorithm is proposed, which can be applied to the environment of heterogeneous wireless networks.An optimized multi-objective control model adopting improved membership function is designed, in which the minimum total occupied resources of distribution services, the minimum service blocking rate and the maximum network load balancing degree of each candidate network are taken as objective functions.The objective membership function, composed of gaussian and upper limit functions is used to obscure each objective function, then the fuzzy satisfaction maximum-minimum technique is adopted to reformulated this multi-objective optimization problem into a single objective nonlinear programming problem, and the optimal service access strategy is obtained by genetic algorithm.Simulation results show that the algorithm can guarantee the system resource utilization and the service access reliability, as well as decrease the system call blocking probability compared to the reference algorithms.关键词：heterogeneous wireless networks;access control;load balancing;multi-objective optimal control2|1052|7更新时间：2025-07-16
- 摘要：Linear network coded cooperation (LNCC) is a technology that integrates linear network coding into cooperative communication.It can improve the spectrum efficiency and decrease outage probability of data transmissions.In this paper, the outage probability of the two-slots LNCC with M(M≥2) users is theoretically analyzed, tight approximated outage.Monte Carlo simulations are conducted to verify the theoretical analyses.Moreover, the asymptotic outage probability and the diversity order of two-slots M-users LNCC are also studied.In order to demonstrate the benefits introduced by linear network coding to cooperative communication, the performance comparison between the two-slots M-users LNCC and the traditional M-users Decode-and-Forward cooperation with the same diversity order is carried out.The results show that given the same effective spectrum efficiency, the outage probability of two-slots M-users LNCC is greatly lower than that of the latter.关键词：cooperative communications;linear network coding;outage probability;multiuser2|1026|1更新时间：2025-07-16
- 摘要：Compared with traditional fountain codes, fountain codes with feedbacks can decrease the decoding overhead effectively.The degree distribution has a very important influence on the decoding efficiency of fountain codes.This paper proposes a new scheme of degree distribution under partial information and we use it in fountain codes with feedback.In the first place, we present an optimum monomial degree distribution with less decoding overhead, and then we combine it with shifted robust soliton distribution (SRSD).At last, we get the improved SRSD (ISRSD) through parameter adjustment.Simulations verify the encoding performance of fountain codes under parity information using ISRSD is greatly improved compared with traditional SRSD.关键词：fountain codes;LT codes;belief propagation decoder;shifted robust soliton distribution212|1289|4更新时间：2025-07-16
- 摘要：In this paper, the utility model is introduced into power control of wireless sensor network and a utility model-based distributed power control scheme (abbreviated UMDPC) is presented.This scheme establishes the correspondence between the transmission power of sensor nodes and utility model, and optimizes the link reliability and energy consumption with a unified network utility optimization (NUM) framework.Then this NUM problem is proved to be a convex optimization problem.A distributed optimization algorithm is proposed to calculate the optimal transmission power of each node by using dual decomposition techniques.Finally, experiments are performed to evaluate the performance of the proposed scheme.Simulation results show that UMDPC scheme can maximize network utility and improve energy utilization efficiency.关键词：wireless sensor network;utility;power control277|1675|3更新时间：2025-07-16
- 摘要：An orthogonal array based topology transparent MAC(Media Access Control) protocol named MIMO_O_TTMA(MIMO Supported Orthogonal Array Based Topology Transparent Multiple Access) is proposed for MIMO(Multiple Input Multiple Output) Ad Hoc networks.The protocol utilizes the orthogonal arrays to assign slots for network nodes, in each assigned slot, the transmitters determine the number of streams to be used by exchanging the RTS/CTS(Request To Send/Clear To Send) packets with their destination nodes, in this way, the nodes can opportunistically use the spatial multiplexing(SM) of MIMO to enhance the network performances.In addition to ensuring at least one collision-free slot in a frame for each node, the MIMO_O_TTMA allows the frame length to be flexibly chosen in certain range, which provides favorable conditions for optimizing the protocol performances.To evaluate the performance the MIMO_O_TTMA, a probability method is used to analysis the throughput of the protocol.Numerical results show that, compared with the existing topology transparent MAC, MIMO_O_TTMA can effectively improves the network throughputs.关键词：MIMO(Multiple Input Multiple Output);Ad Hoc networks;MAC(Media Access Control) protocol;orthogonal arrays201|882|1更新时间：2025-07-16
- 摘要：The detection performance of the Moving Target Detection (MTD) method of the radar target descends badly in complex sea clutter background, Also, The Locally Optimum Detector only works well for the weak target in the low signal clutter ratio background, Therefore, a fractional lower order matched filter detection method is proposed, which is obtained based on the fractional lower order statistics.The proposed method suppresses the non-Gaussian clutter by the signed power and whitens the correlated clutter by decomposing the clutter fractional lower order covariance matrix, at last the matched filter is used to get higher signal clutter ratio.Simulations and real data results show that, the detection performance of the proposed method obviously outperforms the MTD and LOD method in non-Gaussian correlated clutter background.关键词：non-Gaussian correlated clutter;signed power;fractional lower order covariance;clutter whitening228|1148|7更新时间：2025-07-16
- 摘要：Collaborative simulation of complex systems need Run Time Infrastructure (RTI) software to solve the problem of data exchange between heterogeneous models and heterogeneous simulation software.But the TCP/IP communication mechanism of RTI cannot make HPC High Speed Network in the simulation which is the strongest advantages of Infiniband (IB).To solve this problem, this research designs the RTI network optimization based on RDMA communication mechanism, which through the module decomposition and network optimization of CERTI software in open source HLA project, made the IB-CERTI software which run on IB.Eventually, in the experiment of comparison RTI software network performance under different network environment, the experiment results show the efficiency of the IB-CERTI software under simulation communication, especially the larger amount of interactive data between simulation federates, the more efficiency in improving simulation data transmission.关键词：Infiniband network;remote direct memory access (RDMA);CERTI;high level architecture (HLA);high performance computer (HPC)372|1554|1更新时间：2025-07-16
- 摘要：For long-code direct sequence spread spectrum (DSSS) signals in non-cooperative communication systems, a semidefinite relaxation approach to spreading waveform estimation is proposed, and the Cramer-Rao lower bound (CRB) for the spreading waveform estimation is also derived under the deterministic signal model.We first derive the maximum likelihood estimate (MLE) of spreading waveform.Then, due to the MLE problem being a non-convex combinatorial optimization problem, we approximate it as a semidefinite programming problem which features polynomial worst-case complexity by relaxing the constraints.The simulation results demonstrate that the proposed estimator significantly outperforms the existing estimators and can achieve the CRB as the signal-to-noise ratio increases.关键词：long-code DSSS signals;maximum likelihood estimate;semidefinite relaxation;spreading waveform estimation;Cramer-Rao lower bound177|856|4更新时间：2025-07-16
- 摘要：In this paper, a novel approach is presented to evaluate the call blocking probability in downlink of cellular Orthogonal Frequency Division Multiple Access (OFDMA) networks.Based on this analysis, call blocking probability in downlink of two-hop-relay OFDMA cellular networks is evaluated.Capacity analysis of traditional cellular networks like GSM and CDMA cellular networks cannot be applied to OFDMA cellular networks because for the latter every incoming call requires a random number of sub-carriers.In this paper, incoming calls are divided into classes according to their requirement for sub-carrier.Then, the traditional and relay OFDMA cellular network are modeled as the multi-dimensional Markov chain and their call blocking probability in downlink are evaluated.Finally, through numerical calculation, the impact of the various parameters on the performance is analyzed.This analysis shows that the capacity of OFDMA cellular networks which added relays has been greatly improved.关键词：orthogonal frequency-division multiple access(OFDMA);two-hop-relay;downlink;call blocking probability;Markov chains232|1138|0更新时间：2025-07-16
- 摘要：According to the experimental measurement results, combining with the technology computer aided design (TCAD) simulations, the hot-carrier degradations of 1.8V pMOS under different gate voltages are investigated in this paper.The results show that, with the gate voltage increasing, the electron injection mechanism changes to the hole injection mechanism, leading to the increases of the saturation drain current (Idsat), linear drain current (Idlin) and threshold voltage (Vth).However, because there is not any carrier injection, the degradation trend begins to change at Vgs=90%*Vds.Moreover, the study also discovers that the generated interface states have more impact on the hole mobility in the depletion region than that in the non-depletion region.As a result, the degradation of forward Idsat is bigger than the degradation of reverse Idsat.However, the degradations of forward Idlin and reverse Idlin are same since the whole channel is not depleted under Idlin condition.关键词：hot-carrier;different gate voltage stresses;forward and reverse degradations194|1678|1更新时间：2025-07-16
- 摘要：The combination and divergence of multi-target tracks are very common in the engineering practice, which make it more difficult for the track fusion.In this paper, a novel track fusion method with an adaptive sliding mean window is proposed.Meanwhile, the adaptive associated matrix of proposed method is also given here.The proposed method could adaptively measure the effect of history track on the current track for the multi-target, thus judge the track combination and divergence, effectively and accurately.Furthermore, the simulations are performed with two sensors and two targets, have also shown that the proposed method is valid and stable for the track fusion, especially to the track combination and divergence.关键词：OSPA (optimal sub-pattern assignment);track fusion;track combination;track divergence260|1418|2更新时间：2025-07-16
- 摘要：In-network caching schemes in information-centric networking (ICN) often consider the popularity granularity in the content level, which ignores the character that different parts of a content may have different popularity.This paper proposes a segment Level-based Implicit Cooperation cAche (LICA) scheme.LICA assigns a cache router a level based on its location and archives implicit cooperation with tags in interest and data packets.We compare LICA with other caching schemes and the simulation results show that LICA has higher average hit ratio, lower average hop count of content retrieval, and reduces the network traffic than other schemes, which will improve the experience of users in real-time streaming media service.关键词：information centric networking;in-network caching;segment popularity292|1546|1更新时间：2025-07-16
- 摘要：A direct, easy-to-operate and effective evaluation method for building a qualitative and quantitative uncertainty evaluation transformation model is urgently needed for intelligent vehicle evaluation research.It has been a challenging problem facing the researchers.Based on cloud model and variable granularity, this paper describes a measurement method.First, we proposed a set of 4S variable granularity measurement system and the three-level IQ variable granularity evaluation system.Then, we transformed the qualitative assessment over the intelligent driving vehicle into a direct image quantitative evaluation via using the Expectation, the Entropy and the Hyper Entropy of cloud model, thus building an uncertainty transformation model from qualitative to quantitative.The Future Challenge 2013 was used as a case to illustrate the model.The analysis shows that in the qualitative and quantitative evaluation, the Expectation, Entropy and Hyper Entropy based on cloud model is the basis of qualitative-evaluation of quantitative evaluation.Moreover, the intelligent vehicle evaluation based on cloud model and variable granularity can efficiently solve the multi-objective particle size measurement of evaluation and descriptive qualitative evaluation of quantitative evaluation, thereby providing solutions to the evaluation of a class of intelligent vehicle research.关键词：cloud model;variable granularity;intelligent vehicle;evaluation research211|1459|13更新时间：2025-07-16
- 摘要：To detect flip ambiguity for range-based three-dimensional node localization in wireless sensor networks, we have proposed and proved that flip ambiguity detection for three-dimensional node localization is equal to whether there is a plane intersecting with all range error spheres of the reference nodes, which is called the existence of intersecting plane (EIP) problem.To solve EIP problem, we further have proposed two solving algorithms:common tangent plane algorithm (CTP) and orthogonal projection algorithm (OP).CTP adopts the principle of boundary detection, while OP transforms EIP problem into an angle calculation problem and adopts a coordinate transformation method to solve the problem.The simulation experiments demonstrate that CTP has good detection results, but its computational complexity is too high;however, OP has almost the same detection results as CTP and has lower computational complexity.关键词：Wireless sensor networks;three-dimensional node localization;flip ambiguity;common tangent plane;orthogonal projection270|922|5更新时间：2025-07-16
- 摘要：Drude empirical models are frequently used for description of dispersion characteristics of many media, such as plasmas, and metals.Reconstructed electrical properties by directly using wide-band measured data in time domain, are better than those by application of any single-frequency technique, in amount of information, and resolution of generated images.One of difficulties in time-domain reconstruction of dispersive characteristics is their frequency correlation.In order to overcome this difficulty, an electromagnetic (EM) inverse scattering technique in time domain is proposed, in which four kinds of frequency-independence parameters from a Drude model are estimated simultaneously.Main segments for the technology are:(1) formulating the inverse scattering problem as a constrained minimization problem with a term of regularization;(2) transforming resulting problem into an unconstrained minimization one;(3) deriving a set of closed gradients of its cost functional;(4) solving iteratively resulting forward and backward sub-problems by a finite-difference time-domain (FDTD) method and any conjugate gradient (CG) algorithm, respectively.In one-dimensional (1-D) and two-dimensional (2-D) numerical examples, necessary measurements are replaced by simulated fields based on the FDTD method, and it is assumed that they are corrupted by an additive white Gaussian noise (AWGN).Numerical results preliminarily confirm performance of the inversion methodology.关键词：electromagnetic (EM) inverse scattering;Drude dispersive media;regularization;finite-difference time-domain (FDTD) method;conjugate gradient (CG) algorithm236|1263|1更新时间：2025-07-16
- 摘要：Stochastic context-free grammar (SCFG) has a promising application prospect in the field of mode recognition and threat estimation of multi-function radars (MFR).The primary limitation of the existing learning algorithms is their huge computing complexity.A fast learning algorithm for the parameters of MFR grammar is proposed, in which the Cocke-Younger-Kasami(CKY) parsing chart is first pre-computed for each training sequence to delete the rules that are not involved in the signal generation.Finally, the estimation of radar grammar parameters is realized with a modified inside-outside (IO) algorithm.The computing complexity is theoretically analyzed, moreover, simulation experiments are provided to verify the algorithm efficiency.Compared with the conventional IO and Viterbi-score (VS) algorithms, more than half operation time is reduced with our proposed algorithm while the favorable estimation accuracy is maintained.关键词：electronic warfare;Multi-function radar;stochastic context free grammar;parameter learning2|877|4更新时间：2025-07-16
- 摘要：As a mainstream solution for next generation optical access network, the TWDM-PON has the characteristics of high bandwidth, long distance, numerous access users etc.In order to effectively reduce the network delay and promote the fairness of resource allocation, an user-behavior aware dynamic resource allocation strategy is proposed for adapting to the increasing differences of user-behaviors in TWDM-PON.According to the dynamic traffic status brought by user-behaviors, the ONU polling mechanism is adjusted in real-time to satisfy the requirements of ONU service level.And the introduction of traffic sub-cycle can make the different grade service alternately send.Finally, for achieving multi-wavelength transmission of load balance, an efficient data block loading mechanism is designed.The simulation results show that the proposed strategy can reduce packet delay more than 50% and keep better fairness during resource allocation, while the utilization rate of network resource can reach 95%.关键词：TWDM-PON;dynamic resource assignment;user-behaviors;bandwidth utilization;traffic delay;fairness219|1059|2更新时间：2025-07-16
- 摘要：This article puts forward a clustering center selecting algorithm based on quantum harmonic oscillator model (CCSA-QHOM).The algorithm describes the way of data objects finding center of the cluster in clustering problem by taking the change of wave function's probability in the process of high energy level to a lower energy level for theoretical model.It can quickly find the optimal number of clusters and cluster center, computing time has nothing to do with the size of the data set after the dataset being got in grid space.Experiments show that CCSA-QHOM is more suitable for processing the clustering center selection question of dataset in which grid density distribution of each subclass haves a single peak characteristic.关键词：cluster center;quantum harmonic oscillator;number of clusters;grid;peak characteristic208|1279|8更新时间：2025-07-16
- 摘要：It is a problem that the best-effort service model standing for group command transmission causes path competition.To solve the problem, this paper firstly defines effective path statistics network (EPSN) based on Internet, and further describes group multi-constraints multi-objectives optimization problem based on the EPSN.This paper proposes a group command transmission algorithm.The algorithm defines fuzzy ball division, continuous space ant colony optimization and overlapped area solution reliability reduction respectively.The experiment tests validity of the algorithm from service delay rate and transmission success rate.关键词：group command transmission;group multi-constraints multi-objectives optimization problem;path competition;ant colony optimization217|863|1更新时间：2025-07-16
- 摘要：In order to deal with the constraint on accuracy and head movements in natural light, a novel dynamic gaze vector constructed by iris center and inner eye corner is proposed.The gaze vector, which is normalized by iris area to overcome the influences of head movements, is combined with the polynomial mapping model for real-time fixation point calculation, realizing the best mapping relation between the vector and the gaze point.The gaze vector proposed can improve the fixation point estimation precision and eliminate the influences of head movements.关键词：iris;inner eye corner;gaze tracking;natural light226|1510|4更新时间：2025-07-16
- 摘要：Differential evolution is a global heuristic algorithm, which is simple, easy-to-use and robust in practice.Combining with the constraint-handling techniques, it can solve constrained optimization problems.Machine learning often guides population to evolve in the evolution computation, and is widely applied to unconstrained differential evolution algorithm.However, machine learning is rarely applied to constrained differential evolution algorithm, so this paper proposed a constrained differential evolution algorithm framework using opposition-based learning.The algorithm can improve the diversity and convergence of differential evolution.At last, the proposed algorithm framework is applied to two popular constrained differential evolution variants, that is (μ+λ) -CDE and ECHT-DE.And 18 benchmark functions presented in CEC 2010 are chosen as the test suite, experimental results show that comparing with (μ+λ) -CDE and ECHT-DE, our algorithms are able to improve global search ability, convergence speed and accuracy in the majority of test cases.关键词：opposition-based learning;differential evolution;constrained optimization;convergence246|1375|6更新时间：2025-07-16
- 摘要：One grouping N-ray tracking tree RFID(Radio Frequency Identification) anti-collision algorithm (CBGN, Collision Bit Tracking Tree Algorthm Based on Grouping N-ray) for signals collision caused by RFID(radio frequency identification) tags multiple access of shared channel is proposed.We estimated the number of tags by the maximum likelihood bit estimation method (MLE, Maximum Likelihood Bit Estimation).Based on MLE, we allocated the set of tags into different groups through the tag identification, identified grouped tags via N-ray tree, and reduced recognition time by CBGN under combining grouping and N-ray identify.Finally, we derived the optimal grouping coefficient of different N-ray tree using the average identify tag cost time in communication link, further obtained the optimal N values and the corresponding optimalcoefficient of clusters.Our theoretical analysis and simulation results showed that CBGN algorithm had the characteristics of strong robustness and low communication complexity.关键词：radio frequency identification;anti-collision;N-ray;throughput rate120|1490|4更新时间：2025-07-16
- 摘要：How to determine camera's next best view based on current information is a challenging problem in visual field.A next best view approach was proposed based on the occlusion information of a single depth image.Firstly, to establish the model for occlusion region external surface, the quadrilateral meshes for occlusion region external surface were obtained according to the occlusion information of a depth image in initial view.Secondly, the model for next best view was constructed by considering both the visible quadrangle and the loss information in next view.Finally, the next best view was achieved by solving the model with gradient descent method.Compared with the existing methods, the proposed approach does not limit the camera position on a fixed surface or need the priori knowledge of visual object.Experimental results demonstrate its feasibility and effectiveness.关键词：next best view;depth image;occlusion information;external surface of occlusion region;gradient descent method176|873|1更新时间：2025-07-16
- 摘要：To retain the position relationship of pixels when image analyzing and dimension reducing, we extend the one-dimensional compressive sensing theory to two-dimensional, and establish a two-dimensional compressive measurement model for sparse signal.We study an adaptive gradient descent recursion algorithm for two-dimensional signal, and propose an image hierarchical feature extraction and retrieval method.Firstly, it conducts grid discrete division on the RGB color space, and mapping to the image by hierarchical operator.It defines an extended GLCM based on color grid space, and extracts the hierarchical measurement feature, texture feature and hierarchical color statistical feature by the two-dimensional measurement model.The hierarchical measurement feature of image reflects the position relationship between the image color and pixel, and the extended GLCM reflects the texture feature.Secondly, it calculates the original signal difference and sparse value between images by the AGDR algorithm.Finally, it calculates the overall similarity metrics between images by combining the two hierarchical feature difference, the sparse value and the color statistical feature.The simulation results show that the image retrieval method which applying hierarchical two-dimensional compressive sensing measurement and AGDR algorithm has superior performance on retrieval time, recall and precision, it provides a new idea for the image retrieval.关键词：two-dimensional compressive sensing;image retrieval;image hierarchical feature;texture feature;adaptive gradient descent recursion2|1755|6更新时间：2025-07-16
- 摘要：This paper surveys the state of the art of schema inference from XML data.First, the formal models based on regular tree grammar for commonly used XML schema languages are presented.Then, the existing works on XML schema inference are summarized and compared from various aspects such as inference methods, target schema languages, supported expressiveness, regular expression types corresponding to the content models, and so on.In addition, inferences of some basic integrity constraints from XML data are also introduced.Finally, this paper points out the defects of current research and discusses some potential future research directions.This paper aims to offer a detail overview, comparison and analysis of the mainstream methods and recent progress in this field, expecting to be beneficial for subsequent research.关键词：XML(Extensible Markup Language);schema inference;regular tree grammar;regular expression163|2133|1更新时间：2025-07-16
- 摘要：In recent years, with the rapid growth of scientific data, large data analysis has become urgent problems. More and more large-data processing methods are modified to perform computation under parallel and distributed computing environment.In this paper, we present a hybrid architecture for large volume data visualization and processing.Various hardware environments and technologies are integrated in this architecture to perform interactive operations on very large volume datasets.All the datasets are stored in a data center with a gigabit network environment.The time-consuming data processing tasks are dispatched to the computing nodes connected to the same network, while the visualization and interaction operations are executed on a high-performance graphics workstation.OpenCL and OpenMP are used to implement volume rendering algorithms for accelerating visualization of a hierarchical volume data structure by both GPU and CPU with multi-cores, and some out-of-core algorithms are also presented to process the large dataset directly.The experimental results and practical application indicate that the hybrid architecture and methods presented in this paper are effective and efficient for the processing and visualization of very large volume datasets.关键词：volume rendering;graphics processing unit(GPU);out-of-core;parallel computing;large data104|1100|1更新时间：2025-07-16
- 摘要：Onset detection of action surface electromyography (sEMG) signals is important since it has great impact on the accuracy of subsequent sEMG analysis such as in prosthetic control, human computer interaction and clinical diagnosis and assessment, etc.This study presents a segment onset detection method based on sample entropy.Firstly, sEMG signals are framed by a fixed-length sliding window and the sample entropy of each frame is calculated.Afterwards, adaptive threshold is set to determine the starting point.Experimental results demonstrate the feasibility of sample entropy to characterize the switching property of action sEMG signals.Meanwhile, compared to moving average and Teager-Kaiser energy operator, the proposed method has advantages in better anti-jamming ability, not only in suppressing short muscular contraction relaxation intervals, but also in suppressing involuntary background spikes.关键词：electromyography;onset detection;sample entropy;Teager-Kaiser energy operator2|2416|12更新时间：2025-07-16
- 摘要：Coordinate Rotation Digital Computer (CORDIC) algorithm for fixed angle of rotation has been widely applied in many fields, including digital signal processing, image processing and robotics.CORDIC algorithm, based on fixed angle of rotation, has an advantage of high data throughput, but it takes up much more hardware resources.To remedy these problems, a hybrid CORDIC algorithm is proposed in this paper, which separates the angle rotation into two steps, unidirectional angle rotations and angle estimation ones.According to the under-damping theory, the unidirectional phase rotations are employed to realize the fixed angle of rotation, which reduces the stage of pipeline and judgment of sign bit.Through the binary representation, the constant factor will be fixed.According to the phase mapping relationship, the high speed and precision fixed angle of rotation is completed.Finally the hybrid algorithm is implemented on a hardware platform and the experimental results show that it can further reduce the number of iterations and resource consumption and obtain high though-put rate.关键词：CORDIC (Coordinate Rotation Digital Computer);fixed angle rotation;pipeline architecture;FPGA(field-programmable gate array)191|1710|11更新时间：2025-07-16
- 摘要：SOQPSK signal has constant envelope and continuous phase, and has high power and spectral efficiency.It will have broad application prospects in satellite communications, deep space communications and aeronautical telemetry systems.To ensure SOQPSK carrier signal can be applied to larger Doppler offset system, this paper presents a SOQPSK signal carrier tracking technology which uses FFT guide COSTAS loop.First, a rough estimate by FFT of the Doppler frequency makes carrier frequency offset be limited to a small range, and then uses the improved COSTAS loop to track carrier residuals and phase error, thus achieving a steady carrier track for SOQPSK signal with large carrier frequency offset.Simulation results show that the proposed algorithm not only is able to track large carrier frequency offset, but also is better to track small frequency offsets than traditional methods.关键词：constant envelope;shaped offset quadrature phase shift keying(SOQPSK);fast Fourier transformation (FFT);COSTAS loop;large frequency offset;carrier tracking224|1277|5更新时间：2025-07-16
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