最新刊期
卷 39 ， 期 3 ， 2011
- 摘要：Different time scales are often found between control systems and their environments.When these systems are modeled as timed automata,such difference can lead to fragmentation of the symbolic state space in the process of applying symbolic model checking techniques to the validation of them.Exact acceleration addresses the fragmentation problem without any side-effect to the reachability properties of the system under consideration.To address the fragmentation problems caused by the acceleratable cycles,this paper introduces an exact acceleration technique based on parking cycle.The length of the parking cycle is constant,without dependency on the window of the acceleratable cycles,and so makes the constructed acceleration simpler,the process of the exact acceleration faster,and both the time cost and the space cost of exact acceleration can be greatly reduced.关键词：model checking;timed automata;acceleratable cycle;exact acceleration;parking cycle2|1318|2更新时间：2025-07-16
- 摘要：The security of filter generators is provided by the filter function.For the resistance to algebraic attack,functions with maximum algebraic immunity were used for designing filter functions.We find that the existing algebraic immune functions have a strong property of rotation symmetry and present a rotation-symmetric attack on the filter functions.We also discuss the rotation-symmetric property of filter functions and its influence on the rotation-symmetric attack.After the survey of the vulnerability of algebraic immunity function to the rotation-symmetric attack,we give a new criterion for the choice of filter function.关键词：cryptography;filter generator;rotation-symmetric function2|999|0更新时间：2025-07-16
- 摘要：We introduce symbolic representation for quantum circuit,and show how n-qubit circuit can be described as a control qubit symbolic vector and a lower-order controlled gate,instead of the representation of higher-order unitary matrix.We extend the loopless Gray code binary generation algorithm and propose n elements k position binary generation algorithm.Besides,a fast quantum simulation algorithm (FQSA) is presented,it divides a qubit state vector into several operand groups,each group is multiplied by the same unitary matrix,and then the output can be given quickly.In contrast to any other state vector based algorithm,FQSA requires less memory,and has an optimal time complexity.The experimental result of QFT indicates that FQSA is more time-efficient and it can provide more qubits circuit simulation under the same condition.关键词：quantum circuit;simulation technique;state vector;Gray code generation;fast quantum simulation algorithm2|1032|1更新时间：2025-07-16
- 摘要：Due to the difficulty in association and estimation of multi-target tracks in the presence of data association uncertainty,clutter,noise and miss-detection.In this paper,a novel data association probability hypothesis density (PHD) filter for multi-target tracking based on Rao-Blackwellized particle filter (RBPF) algorithm is proposed.Firstly,the Gaussian mixture probability hypothesis density (GMPHD) filter has been proposed to estimate the set of all targets at every time step.Secondly,the data-association functionalities of RBPF can be incorporated with the PHD filter to produce the track-valued estimates of individual targets.Simulation results show that the proposed algorithm is more robust and accurate than Label-PHD algorithm which is very prevalent in the PHD tracking domains,also the proposed algorithm can estimate and distinguish each target more effective.关键词：Rao-Blackwellized particle filter;multi-target tracking;probability hypothesis density filter (PHD);track-to-track association2|1417|2更新时间：2025-07-16
- 摘要：A two stage hybrid reduced rank STAP method is proposed for severely non-homogeneous environment in MIMO radar.It firstly suppresses the clutter and then rejects isolated interferers.In the first stage,forward/backward temporal smoothing technique is applied to the limited secondary samples to gain more samples from which clutter covariance matrix is estimated.And then 3DT or 3CAP method is used for clutter suppressing.In the second stage,upon applying forward/backward temporal smoothing technique to the sample obtained from the range gate of interest,the covariance matrix of isolated interferers can be estimated.Subsequently 3DT method is also made use of to reject isolated interferers.The presented method possesses small spatial temporal aperture loss,well robustness to errors and makes good use of statistical information.Computer simulations verify its validity and robustness.关键词：STAP (Space-Time Adaptive Processing);MIMO (Multiple Input Multiple Output) radar;non-homogeneous clutter2|1259|11更新时间：2025-07-16
- 摘要：The basic method to improve efficiency of the BP(Back-Projection) algorithm is the sub-aperture’s way.Choosing the length of sub-apertures and the resolution of sub-images becomes the most crucial step that decides the computation efficiency.The condition that limits the image resolution is analyzed taking the bandwidth and the range error into account.Then a same result presenting the relationship between the sub-aperture length and the resolution is received.A method for dividing the sub-aperture and choosing the image resolution in UWB signal’s circumstance is presented based on the former result.Besides the Multi-Stage Multi-Resolution Back Projection (MSMRBP) algorithm is presented to suit the nonuniform aperture condition.At last the outside experiment’s results are presented to support the former conclusion.关键词：sub-aperture;imaging in polar coordinates;nonuniform aperture;FFBP;motion compensation2|1507|7更新时间：2025-07-16
- 摘要：For capturing various shapes and blurry margins of tumors,a new mass detection method based on Morphological Component Analysis (MCA) and adaptive histogram threshold searching is proposed in this paper.Firstly,MCA method is introduced to restrain the influence of blood vessels and fibrous structures in mammograms.Then,an adaptive threshold searching method is designed according to the histograms of breast region.Finally,following the Gaussian-like growing feature of masses,the suspicious regions are effectively detected according to the adaptive thresholds and multi-intensity concentric layer methods.The experimental results on mammograms illustrate that the proposed method could effectively detect different types of masses with acceptable false positives,and could be a useful tool for assisting doctors.关键词：computer-aided detection;mass detection;morphological component analysis;adaptive threshold searching;multiple intensity layers2|1093|2更新时间：2025-07-16
- 摘要：The Ultra WideBand(UWB) Radar is a promising candidate for detecting human bodies in many fields such as urban-warfare,counter-terrorism and calamity rescue scenarios.Conventional UWB imaging algorithm can not meet the demand in the capability of targets recognition and calculation efficiency.This paper proposed a novel algorithm based on high-speed SEABED algorithm for UWB radar systems in which walking motion was used to replace antenna scanning by assuming a system model.The effectiveness and feasibility of the algorithm is demonstrated via simulated and experimental results.It is shown that the proposed algorithm features simple hardware requirement,low calculation,and high imaging precision,and it can be used to estimate the velocity,image and track walking human bodies.关键词：ultra wideband (UWB) radar;boundary scattering transform (BST);SEABED algorithm;target shape imaging;moving targets tracking2|1947|7更新时间：2025-07-16
- 摘要：Signal reconstruction from finitely number of non-uniform samples on a interval is considered in the frame of shift invariant space.We derive a new interpolation method that is approximately optimal at min-max criterion for signals in a shift invariant space,and can regain Yen’s interpolator for band-limited signals.Based on the derived interpolator,we also propose an effective non-iterative algorithm for min-max signal reconstruction.Some numerical examples are given to show the effectiveness of the new method.关键词：non-uniformly sampling;interpolation;scaling function;shift-invariant space;min-max reconstruction4|1077|0更新时间：2025-07-16
- 摘要：Network traffic anomaly detection is crucial to guarantee stable and effective network operation.Nowadays,although PCA-based network-wide anomaly detector plays an important role,it cannot detect anomalous network traffic effectively in face of poison attacks.In order to solve poison attack problem aiming at PCA-based anomaly detector,poison attack strategies are investigated and classified,two metrics for quantifying poison traffic are proposed and three novel poison attack strategies are put forward.A robust PCA-based anomaly detection algorithm (for short RPCA) is proposed to resist poison attacks.Simulation experiment results show that RPCA algorithm can still perform very well in face of poison attacks,obviously superior to PCA-based anomaly detector,and its running time can satisfy the need of practical network anomaly detection.关键词：anomaly detection;poison attacks;defense strategy;principal component analysis;robustness2|1414|5更新时间：2025-07-16
- 摘要：Compton back-scattering (CBS) is a new technology for ray security inspection,that can enhance accuracy of explosive detection,such as organic contraband.For this task,contraband segmentation of image is very important.One new approach for Compton back-scattering (CBS) image filtering and segmentation using CNN is proposed in this paper.Furthermore,one new way for eliminating isolated point based on CNN and morphologic method is also described.Some detailed analyses and practical results are presented,which demonstrates the successful operation of the proposed algorithm.This new approach is very affordable to parallelism and analog VLSI implementation,which allowing the security inspection of CBS image processing to be performed in real-time.关键词：cellular neural networks (CNN);compton back-scattering (CBS);image segmentation2|1473|1更新时间：2025-07-16
- 摘要：Range-dependence compensation for bistatic STAP on the condition of range ambiguity was studied.Firstly a clutter model for this background was built,the difference between range ambiguity and no range ambiguity was analyzed,and the existing bistatic STAP range-dependence compensation method's deficiency was pointed.Secondly a new method named range-dependence compensation based on data separation was proposed according to the different range gates' clutter character analyses.At last data simulation shows that the new method's signal-to-noise upgrading performance is better than the RBRDC's.关键词：bistatic STAP;range-dependence compensation;space-time likelihood spectra2|1117|2更新时间：2025-07-16
- 摘要：Protecting the Quality-of-Service (QoS) of the primary user is very important in cognitive radio networks.In this paper,a practical constraint is considered that the available spectrum for the secondary users is limited in opportunistic spectrum sharing.An optimal pricing function is derived,which can provide QoS-guaranteed for the primary users and more revenue for the primary service provider.Moreover,some practical environment parameters (such as channel quality,traffic fluctuation) are taken into account in spectrum pricing.In dynamic scenarios,the price can converge to the optimal value by iteration.Simulation results show that the QoS of the primary user can be guaranteed in the proposed pricing,while the profit is not less than that in market-equilibrium-based price.关键词：cognitive radio;opportunistic spectrum sharing;pricing function;QoS2|1294|8更新时间：2025-07-16
- 摘要：An approach of cooperative hunting for multiple mobile targets by multi-robot is presented in an unknown environment,which divides the pursuit process into creating the environment map,forming the pursuiting teams and capturing the targets.The abstract sensor model is designed to search obstacles for hunters.The data sets of attribute relationship is built by consulting all of factors about capturing evaders,then the association rule data mining is used to build the pursuit groups.Through doping out the positions of targets,the puisuit game can be transformed into multi-robot path planning problems.The best path can be found in the environment map.The simulation results show that the mobile evaders can be captured effectively and efficiently,and prove the feasibility and validity of the given algorithm under dynamic environment.关键词：multi-robot;pursuit game;target search;data mining;association rule;path planning2|1157|1更新时间：2025-07-16
- 摘要：An accurate method based on the automatic identification of starmap is put forward in this paper to calibrate optical systems.The basic procedure is to obtain the star's coordinates in image space by processing starmap and calculating the centroid of a star,accurately calculate the star's apparent position,correct the atmospheric refraction,and obtain the the star's coordinates in object space by automatic celestial body identifying techniques,then calculate the lens aberration and the internal and external parameters of an optical system.关键词：starmap;identification;optical system;calibrating method2|1214|5更新时间：2025-07-16
- 摘要：To adapt the character of evolving over time and real-time of sensor data in location tracing service based on RFID,we present an adaptive evolving particle filtering algorithm-AMUR(an adaptive measuring algorithm of underlying uncertainty for RFID data).AMUR adaptively changes the number of samples on the basis of K-L distance,introduces an improved PSO (particle swarm optimization) method to enhance the efficiency of resampling phase of conventional particle filter(SIRPF).Meanwhile,to detect the most optimal samples among candidate sample set,AMUR defines a fitness function based on CWA(conventional weighted aggregation) for PSO which balances the importance between priori density and likelihood densitys.It provides a reliable measure of confidence for initial tuple in the probability RFID database.Experimental comparison of current algorithms shows,AMUR outpreforms current methods in terms of measurement of underlying uncertainties over RFID data,particle degradation and particle depletion.关键词：RFID;Internet of Things;uncertainty;particle filter;adaptive;particle swarm optimization2|1152|3更新时间：2025-07-16
- 摘要：For suppression of nonhomogeneous clutter which is induced by array's non-side looking placement in airborne radar,this paper presents a class of STAP methods using array elevation information.Firstly,we analyzed the clutter components of the tested range cell for non-side looking array,and put forward the idea that near clutter induced by sidelobe of elevation leads to the clutter range dependence.Then the conclusion is achieved that the elevation information of antennas help to suppress the nonhomogeneous clutter based on above analysis,and a hybrid STAP method for nonhomogeneous clutter suppression is presented.Furthermore,we present the internal mechanism of how 3D STAP effectively solve the range dependent clutter nonhomogeneity problem.Finally,the simulation results illustrate the effectiveness of the elevation-based STAP methods for nonhomogeneous clutter suppression.关键词：airborne radar;nonhomogeneous clutter;elevation information;space-time adaptive processing2|1213|9更新时间：2025-07-16
- 摘要：Taking nonholonomic wheeled mobile robot as the research objective,this paper makes a deep study of point stabilization problem.Based on the posture error model in polar coordinate and model of wheeled mobile robots,a asymptotic point stabilization controller is designed by the integration of neural dynamics and Backstepping.This control strategy can solve the velocity and torque jump problem produced by initial error,and make the robot converge to target point quickly.Computer simulations validate the effectiveness of the proposed approach.关键词：nonholonomic mobile robot;point stabilization;posture error model;Backstepping;neural dynamics2|1112|3更新时间：2025-07-16
- 摘要：An algorithm for joint estimation of angle and gain-phase error for bistatic MIMO radar is presented.Array manifolds associated with transmit and receive arrays in the presence of gain-phase errors can be obtained by tri-iterative least-square method.According to the orthogonality of the signal- and noise-subspace,the direction-of-arrivals (DOAs) and direction-of-departures(DODs) of targets are estimated by exploiting MUSIC-like algorithm without any priori knowledge of gain-phase error,and automatically paired.Based on the unique features of array aperture extension,the gain-phase errors are calculated by utilizing the data of the first transmit sensor and the first receive sensor respectively.Compared with the algorithm available,the bearing estimation precision is independent of the gain-phase errors.The gain-phase errors can be solved in closed-form.Performance simulations demonstrate the tolerance limit of the method proposed,as well as its effectiveness and superiority.关键词：gain-phase error;bistatic MIMO radar;multitarget localization;MUSIC-like;closed-form;tolerance limit2|1498|13更新时间：2025-07-16
- 摘要：For the problem of infrared target tracking,we propose a mixture observation model,which can describe both the gradual intensity variation and sudden disappearance of target pixels,and use an online EM algorithm to update the model parameters.The proposed adaptive observation model is incorporated with the interacting multiple model particle filter (IMM-PF) for target tracking.Finally,we extend the algorithm to multiple targets tracking by introducing a likelihood function based on the probabilistic exclusion principle.Experimental and simulation results demonstrate the robustness of our algorithm.关键词：adaptive observation model;interacting multiple model;particle filter;target tracking5|1271|8更新时间：2025-07-16
- 摘要：In terms of the transmission theory of the arrayed waveguide grating,by using Fluoropolymer(PFS-co-GMA),the parameter optimization is performed for a 17×17 AWG multiplexer.In the fabrication of the polymeric arrayed waveguide grating (AWG) device,the cores of the channels and the arrayed waveguides exhibit trapezoid cross-sections instead of originally designed rectangular ones after the reactive ion etching and the stean-redissolution,causes the phaeshift of the light propagating in the AWG,results in the shift of the transmission spectrum,and bring about the variation of the crosstalk.In this paper,by employing the equivalent energy flow method,the AWG parameters have been fixed,and a polymer AWG multiplexer with flat have been designed and fabricated.Measured results show that the central wavelength is 1550.865nm,3-dB bandwidth is about 0.478 nm,insertion loss is 10.5 dB,crosstalk is about -21.5dB.关键词：integrated optics;arrayed waveguide grating;phaeshift;trapezoid cross-sections;equivalent energy flow;crosstalk2|1018|0更新时间：2025-07-16
- 摘要：a method for unsupervised terrain classification of POLSAR imagery is proposed.At first,the polarimetric entropy is utilized to divide terrain scattering into three cases,i.e.high entropy,medium entropy and low entropy.Then surface scattering,double scattering and volume scattering similarities are computed for initially classifying POLSAR image into ten classes.Finally,the initial classification map defined training sets for reclassification based on a new defined parameter to measure the deference degree between two targets.As surface scattering,double scattering and volume scattering are the inherent characteristics of terrain physical scattering,the scattering classified results are more accord with real terrain scattering;the automatic determination of scattering type with scattering similarity overcomes the deficiency of the present scattering classification;the simple computation of the deference degree speeds up the above reclassification.The experiment results with real POLSAR image demonstrate the validity of the proposed method.关键词：scattering similarity;unsupervised terrain classification;deference degree2|1150|4更新时间：2025-07-16
- 摘要：In lateral aberrations of an imaging electron optical system,the paraxial lateral aberrations exit widespread in the whole image plane and that is also the main aberrations which effect image quality of central image and determine limiting image resolution of system.In the present paper,the paraxial lateral aberrations expressed in general form have been derived emphatically by using asymptotic solutions of paraxial equation for imaging electron optics.By using a bi-electrode electrostatic concentric spherical system model,the analytical forms of two special solutions of paraxial rays expressed by asymptotic and accurate solutions have been deduced and tested.The paraxial sphero-chromatic aberrations of second and third order,as well as the paraxial chromatic aberration of magnification of third order,have been deduced.Result completely proves that the approach based on asymptotic solutions to solve the paraxial lateral aberrations is accurate enough and practicable.A simple and clear form for expressing paraxial lateral aberrations of imaging electron optical systems is suggested for practical use,which will have practical significance for study of aberrations of imaging electron optics and for design of image tubes.关键词：electron optical imaging systems;electrostatic cathode lenses;aberration theory of electron optics;paraxial lateral aberrations;paraxial chromatic aberration of magnification2|1514|2更新时间：2025-07-16
- 摘要：A model of clutter of airborne multiple-input multiple-output (MIMO) radar in nonhomogeneous environment is formulated based on spherically invariant random vectors (SIRV).The modified asymptotical maximum likelihood (MAML) method is proposed to estimate the singular normalized covariance matrix of clutter and the modified asymptotical generalized likelihood ratio test (MAGLRT) detector is developed based on it.Simulation results reveal that the MAGLRT detector has a great advantage over conventional Gaussian modeled detector,meanwhile the MIMO radar has better detection performance compared with SIMO radar.关键词：multiple-input multiple-output (MIMO) radar;nonhomogeneous clutter;spherically invariant random vectors (SIRV);modified asymptotical generalized likelihood ratio test (MAGLRT)2|1198|5更新时间：2025-07-16
- 摘要：A rectangular coupled-cavity was proposed as the slow-wave structure (SWS) for the extended interaction oscillator (EIO) in terahertz (THz) wave.Due to the complexity of the SWS,the equivalent circuit method (ECM) was adopted to calculate the dispersion of the SWS.The circuit parameters of the cavity and the coupling slot have been studied in detail.The dispersion of the SWS,which includes different dimension with a round or a rectangular beam tunnel at the frequency 0.12THz and 0.225THz,was theoretically calculated.Specified electromagnetic software was utilized to simulate the dispersion,the coupling impedance and the characteristic impedance of the SWS.By comparison,the theoretical results of the dispersion agree well with the simulation results.关键词：Terahertz (THz);rectangular coupled-cavity;slow-wave structure (SWS);equivalent circuit method (ECM);dispersion2|1131|7更新时间：2025-07-16
- 摘要：A high fidelity wideband radar signature prediction model for space objects with precession is developed,where the micro-motion model,electromagnetic scattering calculation and linear frequency modulated (LFM) radar signal model are integrated.The fidelity of the model is demonstrated by comparing both the radar cross section (RCS) and high-resolution range profile time sequences with anechoic chamber measured data.Wideband LFM radar returns of dynamic space object are simulated and analyzed based on the proposed model,considering the limitations of ideal point scatterers model for the precession target signature simulation and the radar imaging distortions impact of paired echoes.关键词：space objects;precession;wideband radar;signature signal;simulation2|1786|12更新时间：2025-07-16
- 摘要：Existing personalized information services methods have poor adaptability of user interest change.Based on the hierarchy of needs theory,this paper analyzed and classified the reasons of interest change,proposed hierarchical motivations analysis mechanisms of information categories and behaviors,and proposed the personalized information service model.The model analyses the user behavior records,provides diverse recommendations,and sets a feedback monitoring to cope with the interest change actively.Experiments show that the system service supported by the model has a higher quality of personalized service.关键词：personalized service;behavior motivation;Maslow’s hierarchy of needs;requirement change2|1329|9更新时间：2025-07-16
- 摘要：Image perceptual quality assessment is a key problem in image processing engineering.According to the perceptual characters of Human Visual System (HVS),a Just Noticeable Distortion (JND) threshold model is constructed using contourlet transform,which can well qualify spatial frequency sensitivity,orientation sensitivity,contrast masking and neighborhood masking effects of HVS.As a result of taking account of neighborhood masking additionally,this JND model can distinguish the different masking intensity of smoothness,edge and texture domain,and implement more accurate JND threshold.Based on our JND threshold model,the perceptual error between contourlet coefficients is defined,and then a quantitative perceptual quality metric HVSNR is proposed.Experiments demonstrate that our metric can provide quality evaluation well correlated with those given by human observers.关键词：quality assessment;contourlet;HVS;JND;neighborhood masking2|1223|5更新时间：2025-07-16
- 摘要：We propose a CMP oriented variable-way hybrid cache mechanism,named CMP-VH,based on V-Way Cache.CMP-VH turns the last level cache into an optimized private/shared organization.The tag array is private,while the data array is private and shared organized.In CMP-VH,we use reuse information for cache line replacement,and provide implicit and explicit partitioning mechanisms for shared data region.The simulation result of parallel workload SPLASH-2 shows that CMP-VH excelled the pure private or shared cache.关键词：chip multiprocessors;hybrid cache organization;reuse replacement2|1088|1更新时间：2025-07-16
- 摘要：In order to improve the performances of software receiver,an ultra-tight Micro-Inertial Measurement Unit (MIMU)/software receiver integration method is studi ed.The nonlinear tracking loop filter and integrated navigation filter are desig ned by analyzing the nonlinear characteristics of receiver tracking loop and MIM U.The performance of closed-loop ultra-tight integrated system is evaluated by experimental software receiver and Micro-Electro-Mechanical Systems (MEMS) in ertial data collected in real dynamic environments.The results show the improvem ent in the performance of the tracking loop in this ultra-tight aided configura tion under faintish In-phase/Quadra-phase conditions.关键词：ultra-tight integration;software receiver;MIMU;nonlinear filter2|1416|3更新时间：2025-07-16
- 摘要：In this paper,an effective strategy of point multiplication scheduling and an improved algorithm of dual-field high radix Montgomery modular multiplication are proposed. Based on them,a new high-performance scalable public-key cipher coprocessor architecture for RSA and ECC computing acceleration is designed,which is implemented using the 0.18 μm 1P6M standard CMOS technology.The coprocessor has strong scalability and flexibility,which can support the modular exponentiation up to 2048 bit and the dual-field elliptic curve scalar multiplication up to 576 bit by enlarging the high-speed memory on chip and using the radix-length as processing base.The measured result shows that the coprocessor chip has high performance for accelerating the computation of RSA and ECC and can perform one 1024-bit modular exponentiation only in 197 μs ,one the prime field 192-bit scalar multiplication only in 225 μs and the binary field 163-bit scalar multiplication only in 200.7 μs.关键词：coprocessor;elliptic curve cryptography(ECC);Montgomery multiplication;scalability2|1580|3更新时间：2025-07-16
- 摘要：There are choice collusion attack,random collusion attack and linear collusion attack in CPK.The user’s private key of this algorithm was generated by multiplying the basic private key with the inverse of the assistant private key.The basic private key and the assistant private key was the result of combining the elements of the basic private key matrix and the assistant private key matrix separately.The relationship among user’s private keys is nonlinear.By analyzing,this algorithm can defend from the choice collusion attack and random collusion attack that existed in CPK.The size of assistant key matrix can be chose according to need;the security of the system can be controlled.关键词：CPK;collusion attack;ECC2|1216|5更新时间：2025-07-16
- 摘要：Soft errors,caused by the radiation of cosmic rays,are one of the top challenges for space computing.With the continuously progress of integrated circuits,the dependability of modern processors is increasingly affected by soft errors.Currently,few works analyze the impact of soft errors from the perspective of software.This paper presents a quantitative approach,named PRASE,which is able to analyze the effect of soft errors to the reliability of a given program.Moreover,the analytical performance is increased significantly with the help of the basic block analysis and three arithmetic laws.The experiments show that the reliability of a program has a connection with its native structure.Furthermore,the analytical results also identify the vulnerabilities of a given program under the occurrence of soft errors.These contributions are in favor of implementing the high efficient algorithms for tolerating soft errors.关键词：soft error;single event upset;program reliability analysis;error propagation2|1280|5更新时间：2025-07-16
- 摘要：DOA estimation algorithm of coherent sources for MIMO radar is presented by applying the diversity of the transmitted waveform and the symmetry of the transmitting and receiving array.The receiving data samples are reused to increase the number of samples,and obtain the receiving signal of transmitting and receiving virtual sub-arrays.The covariance matrixes of the virtual sub-arrays are derived utilizing the smoothing invariability and the DOA estimation precision is improved.Numerical examples are simulated to verify the effectiveness of the algorithm.关键词：MIMO radar;coherent sources;spatial smoothing;DOA estimation3|1364|10更新时间：2025-07-16
- 摘要：Targets with micro-motions have modulation effects on radar echoes,which vary for different radar waveforms.With high range resolution and Doppler resolution simultaneity,Orthogonal Frequency-Division Multiplexing (OFDM) radar signals can reveal the modulation effects more completely and more profoundly.At the beginning,based on the model of OFDM radar echoes of point-scattering targets with micro-motions,the modulation mechanism is derived,at two aspects of High Resolution Range Profile (HRRP) and micro-Doppler.And then,the relationship between the modulation effects,the parameters of radar and micro-motions is analyzed.It comes to a conclusion that the OFDM radar signals combine the advantage of Linear Frequency Modulated (LFM) signals and Pulse Doppler (PD) radar signals on micro-motion analysis,and they are more favorable for micro-motion feature extraction and target recognition.Finally,the results from simulations and anechoic chamber data prove the validity of the conclusion.关键词：micro-motion;OFDM;high resolution range profile;micro-Doppler;time-frequency transform2|2336|9更新时间：2025-07-16
- 摘要：A new image fusion method for multi-focus image is presented based on multi-level sub-block and iterative method.In order to simulate the system of re-imaging,multi-focus images are convolved with Gaussian functions.Source images and re-imaging images are partitioned into multi-level sub-blocks by different sizes.The gray deviation of the average between source images and re-images is used to judge whether the block is focused.The subjection of image blocks are judged by the principle of consistency.Images are divided into three regions:clear region,fuzzy region and border region,based on iteration method.Finally,the clear regions are merged into the fused image.Experimental results show that the proposed method provides superior performance over conventional fusion methods in improving the quality of fused images.关键词：image fusion;multi-level sub-block;iteration method;multi-focus image2|1371|10更新时间：2025-07-16
- 摘要：Variable size block motion estimation can improve encoding performance,but increases the computational time.A fast motion estimation algorithm based on multi-search centers prediction and dynamic search range adjustment was proposed to speed up the computation.The multi-search centers prediction analyzes motion vectors of spatial and temporal adjacent blocks and results multiple predictive motion vectors which are used as search centers.Compared with the traditional motion vector prediction,the proposed prediction method can improve up to 14.6% prediction accuracy.According to the count and magnitude of the predictive search centers,the search range is dynamically adjusted to further reduce the computational complexity.Experimental results show that the proposed algorithm can reduce about 96.22%,59.50%,and 39.06% computational time separately compared with the fast full search algorithm,UMHS algorithm,and EPZS algorithm in H.264 reference software,while keeping similar rate-distortion performance.关键词：fast motion estimation;multi-search centers;dynamic search range adjustment;variable size block;H.264/AVC2|1120|3更新时间：2025-07-16
- 摘要：As the performance of STAP of airborne bistatic radar is seriously affected by the range ambiguous clutter and the range nonhomogeneous peculiarity of clutter data samples,an orthogonal projection-Doppler warping method was put forward to cancel the range ambiguous clutter and compensate the nonhomogeneity between clutter data samples.Firstly,this method constructed a space and a time orthogonal projection matrix,which based respectively on the space and the time Doppler frequency of the clutter which returned from the nonambiguous range loop,and used these matrixes to form a new clutter data matrix.Secondly,it gave the new clutter data a Doppler warping to reduce the range nonhomogeneous of samples.The simulation indicates that this method greatly improves the performance of STAP under various bistatic geometries.关键词：airborne bistatic radar(ABR);space-time adaptive processing(STAP);range ambiguous;range nonhomogeneous;orthogonal projection(OP);Doppler warping(DW)2|1372|5更新时间：2025-07-16
- 摘要：This paper presents a phase unwrapping algorithm based on the unscented particle filter (UPF) for synthetic-aperture radar (SAR) interferometry.This method provides independence from noise statistics and is not constrained by the nonlinearity of the problem.This technique performs simultaneously noise filtering and phase unwrapping by the optimal data fusion approach.In addition,the importance density function is integrated with the latest observation information and is more in line with the posterior probability distribution of true phase by using an unscented Kalman filter (UKF) to carry out particle update,which also enhances the accuracy and the efficiency of the proposed method.Simulation and real data processing results validate the effectiveness of proposed method,and show a significant improvement with respect to the EKFPU algorithm and other conventional unwrapping algorithms in some situations.关键词：unscented particle filtering;path-following strategy;SAR interferometry2|1336|6更新时间：2025-07-16
- 摘要：Iris liveness detection is a necessary module for iris recognition because iris recognition systems are easily attacked by fake irises.This paper proposes to prevent fake irises using iris images at 860 nm and 480 nm wavelengths.According to spectral characteristics of human eyes,relative number of conjunctival vessels (RNCV) and entropy ratio of iris textures (ERIT) are extracted.The final detection results are output after the trained support vector machine (SVM) is used to classify these feature vectors.Experimental results on the constructed fake iris database show that our algorithm can effectively exclude printed images,artificial eyes and colored contact lenses and the execution time can meet the requirements of the real-time applications.关键词：multi-spectral images;liveness detection;conjunctival vessel detection;wavelet packet decomposition2|1862|3更新时间：2025-07-16
- 摘要：A definition of multi-secret sharing visual cryptography has been proposed,which supports multiple qualified sets and shares operations.Based on the area marking and the basis matrices of single secret sharing visual cryptography,the procedures of multi-secret sharing and recovering are designed.Furthermore,a scheme is realized.At last,the effectiveness is proved and verified by experiments.关键词：visual cryptography;multi-secret sharing;area marking2|1558|7更新时间：2025-07-16
- 摘要：This paper presents a type of antenna structure,in which a Γ structure is fed by monopole through electromagnetic coupling.Simulation and experimental results show that,compared to the general monopole antenna,the height of this antenna can be cut in half,the relative bandwidth can be broadened to 66%.So this structure achieves miniaturization and broadband of antenna.Signal radiated by this antenna has a linear phase-frequency character and small distortion,so it can be used to send broadband signals.By special designing,we can improve matching and the gain.The VSWR(Voltage Standing Wave Ratio) is less than 2 in the whole working bandwidth,while the gain increases about 2 dBi at the low frequency of the working bandwidth and 1 dBi at the high frequency.关键词：electrically small antenna;Γ structure;miniaturization;broadband2|1332|0更新时间：2025-07-16
- 摘要：Wireless mesh network (WMN) is one of the important candidates for wireless broadband access services.In order to meet the requirements of capacity of wireless broadband access,mesh routers in WMN are often needed to equip with several radio interfaces and uses a number of orthogonal channels.Interference and collisions may be reduced in recent channel allocation schemes,but can not be completely avoided.A centralized inter-cluster scheduled interface-clustered channel assignment (ICCA) scheme is designed to completely eliminate interference and collisions in order to enhance network throughput.It can reduce the transmission delay that is especially fit for real-time services.关键词：wireless mesh network;multiple radio multiple channel;interface-clustered channel assignment2|1420|4更新时间：2025-07-16
- 摘要：A technique for constructing highly nonlinear balanced functions is described.It is shown that a balanced Boolean function with high nonlinearity on even number of variables can be obtained via modifying Maiorana-McFarland type bent functions.A conjecture about the upper bound of the nonlinearity of a balanced Boolean function on even number variables is given.关键词：cryptography;Boolean function;balance;nonlinearity2|1250|3更新时间：2025-07-16
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