最新刊期
卷 39 ， 期 6 ， 2011
- 摘要：Parameter errors of the interferometric synthetic aperture radar (InSAR) system influence the vertical accuracy significantly.In this paper,the error sources of the InSAR system is analyzed and classified according to their properties,then the height error model is derived.Using the ground control points(GCPs) and the height error model,a systematic height error arrangement in the whole swath can be obtained with the least-squares method.Based on the error properties,the systematic height error contributions of constant systematic error and slowly changed systematic error can be abstracted from the whole systematic height error,and the baseline error can be derived.The simulation demonstrates the validity of this method.关键词：interferometric synthetic aperture radar (InSAR);systematic height error;error classification;height error model;baseline estimation2|1826|2更新时间：2025-07-16
- 摘要：A new near-field source parameter estimation method based on the combination array is proposed,which can provide the reliable prior information for the noise sources localization and identification.The form of the array is a uniform pressure sensor array,in whose center there is one three-dimensional vector hydrophone.By utilizing this combination array,the three-dimensional parameters of the near-field sources including the azimuth angle,the elevation angle and the distance can be achieved.This method only uses the second-order statistics information,and transforms the three-dimensional parameter estimation problem into several one-dimensional search problems,so it reduces the computational complexity and does not need additional parameter pairing algorithm.关键词：vector hydrophone;directivity sharpening;near-field source parameter estimation;generalized ESPRIT3|1055|1更新时间：2025-07-16
- 摘要：PSO can easily suffer from the premature convergence when solving complex multimodal problems.It is an important method for relieving the premature convergence to control the population diversity by adjusting the inertia weight and acceleration coefficients.However,the setting of the inertia weight and acceleration coefficients is dependent on the design of experiments and lack of the support of the theory.To solve this problem,the new method is proposed in which the change of the prospective population diversity is used to adjust the setting of learning parameters in this paper.Firstly,the expression of the population diversity at the next time step is computed in the condition of the known current population state.Then the mathematic relationship between the inertia weight,acceleration coefficients and the population diversity at the next time step is presented by the extremum theory on multivariate function,which provides a theoretical foundation to control the population diversity by learning parameters.2|1337|10更新时间：2025-07-16
- 摘要：A new STAP method is proposed suitable for multi-channel SAR system:the frequency-Doppler domain wideband long CPI STAP method.The introduced method can adapt to the range walk along slow time and space dimension,so it can make use of both long CPI and long baseline.By utilizing the large bandwidth of the SAR system,the proposed method can eliminate the blind speed introduced by long sparse baseline.The introduced method can detect moving targets even with small non-zero range velocities or non-zero azimuth velocities,and can estimate their range and azimuth velocities.关键词：GMTI;multi-channel SAR;STAP wideband long CPI;frequency Doppler domain2|1641|3更新时间：2025-07-16
- 摘要：For products whose failures are defined in terms of performance characteristics exceeding their critical values,reliability assessment can be based on degradation measurements by using degradation models.Since the time-to-failure depends on the level of critical value,more life data can be obtained by tightening the critical value.This paper presents a method for the estimation of life distribution for long life products by using life data from degradation measurements.The relationship between life and critical value and stress is modeled and used to estimate the life distribution at a usual critical value design stress.The model parameters are estimated by using maximum likelihood and least square method.At last,an example is used to illustrate the validity of the method.关键词：accelerated degradation tests(ADT);degradation model;long-life products;reliability assessment;tightened critical values2|1054|2更新时间：2025-07-16
- 摘要：The MUSIC-like beamforming method (MBM) is presented to improve the wideband direction of arrival (DOA) estimation performance of the frequency domain beamforming method.The wideband signal is first disparted to several narrowband signals in the frequency domain.Then the summation of the MBM spectrum at each narrowband is taken as the estimated spatial spectrum.Consequently,the peak locations provide us the wideband DOA estimation.The MBM deserves a frequency-invariant beampattern in a wide frequency band with equivalent computation load compared with that of the conventional beamforming (CBF).The simulation results show that the wideband DOA estimation performance and resolution ability of the MBM fall in between the incoherent CBF and incoherent MUSIC.关键词：direction of arrival;wideband signal;beamforming;MUSIC2|2427|21更新时间：2025-07-16
- 摘要：It is well known that the Particle Swarm Optimization (PSO) algorithm easily falls into the local optimal solution.In this paper,we defined a concept of PSO particle-search center,and analyzed the probability density of the center between global and local optimal solutions in random state.A uniform searching particle swarm optimization (UPSO) algorithm whose particle-search center uniformly distributed between local and global optimal solutions is proposed based on that analysis.By analyzing the comparative experiments between UPSO and PSO algorithm with seven benchmark functions,we found that the UPSO and its improved algorithms are more stable and can improve the convergence efficiency in function optimization,especially in non-uniformly multimodal function optimization.关键词：particle swarm optimization;optimization algorithm;uniform search2|2213|37更新时间：2025-07-16
- 摘要：Memory subsystem plays a vital role in embedded systems.Since it’s hard to obtain increasingly capacity for traditional memory systems,NAND Flash based SSM (solid state memory),especially heterogeneous SSM with RAM (read only memory),is becoming more and more widely used.Corresponding to low speed problem in SSM,cache and parallel technologies are commonly used for optimization.However,it poses a significant challenge to integrate them into a single solution in most applications.This article presents a mechanism based on cyclic buffer and integrates caches with parallel technologies.Cache and Storage modules are connected through a switch-matrix.A unified buffer is introduced to handle errors.Benefiting from dual bus infrastructure,also flexible addressing and scheduling strategies,this approach can largely improve data level parallelism.Verification and empirical experiment results demonstrate the concept with high speed and satisfactory performance.Prototyping system shows the feasibility of the placement layout and routing within circuit board.关键词：heterogeneous memory system;switch matrix;cache scheduling2|1199|5更新时间：2025-07-16
- 摘要：Due to the sparsity of inverse synthetic aperture imaging lidar (ISAIL) echoes in range-Doppler (R-D) plane,a phase adjustment algorithm for ISAIL is proposed.The sparsity is used as a global constraint condition for phase adjustment,then the regularization method is brought in to solve this optimization problem.Hadamard multiplication and fast Fourier transform are applied to improve the computation efficiency.Compared with the traditional ISAIL imaging algorithm,image of target is well focused by our method under the condition of low SNR or lack of echoes.The ISAIL imaging experiments with numerical and measured data validate the feasibility and effectiveness of the proposed algorithm.关键词：inverse synthetic aperture imaging lidar;phase adjustment;sparsity;regularization2|1090|1更新时间：2025-07-16
- 摘要：In view of histogram equalization regarded as typical ill-posed problem,the adjustable histogram equalization method is explaned by regularization theory,and its improvement is proposed in order to obtain the better effect of image enhancement.Firstly,the objective function of adjustable histogram equalization method is simplified and explaned by means of information energy as a regular item.Secondly,in consideration of the dual relationship between information entropy and information energy,the new adjustable histogram!equalization model based on information entropy as regularization is obtained.Thirdly,the regular item coefficient choosing method of adjustable histogram equalization is presented by means of information entropy or energy of gray levels probability distribution.Finally,the adjustable histogram equalization improvement method based on modifying cumulative probability of gray levels is proposed in order to improve the image enhancement effect of traditional histogram equalization method.Experimental results show that the improvement method of adjustable histogram equalization is effective.关键词：image enhancement;histogram equalization;ill-posed problem;information energy2|1589|9更新时间：2025-07-16
- 摘要：A baton handover strategy which is applied to integrated services (voice/data) in TD-SCDMA mobile communication system is proposed.This strategy reserves channels for voice handover calls,defines different handover priorities according to voice user’s attribution,and gives voice handover calls and new voice calls preemptive priority over channels serving for data calls.Simulation results show that this strategy reduces blocking probabilities of VIP voice handover calls and high-speed handover calls by at least 50% when the system voice traffic is heavy.Furthermore,this strategy reduces the data call blocking probability and queue length while the system has heavy data traffic.Besides,data call transmission delay is decreased by nearly 0.01s.So it improves the overall system QoS.关键词：TD-SCDMA;baton handover;channel reservation;preemptive priority2|1180|2更新时间：2025-07-16
- 摘要：An algorithm for wideband direction of arrival (DOA) estimation based on chirped Z transform (CZT) is proposed.According to the ideally focusing condition of uniform linear array (ULA),an idea in the wave vector space to solve focusing matrices and the corresponding solution are presented:A row vector in the focusing matrix at the focusing frequency is chosen,as for the focusing matrix of an arbitrary sub-band,the spectrum of the row vector at same position is calculated with CZT,and all vectors are obtained by inverse fast Fourier transform (IFFT).With this method,any value within the signal frequency range can be chosen as the focusing frequency,and good asymptotic unbiased performance can be acquired without any pre-estimated DOA.The validity of these conclusions is validated with computer simulations and pool experiments.关键词：wideband direction of arrival (DOA) estimation;coherent signal subspace method (CSM);chirped Z transform (CZT);CSM based on CZT with Invariable Aperture (CZTIA)2|1215|1更新时间：2025-07-16
- 摘要：Independent component analysis (ICA) is one of the most important methods for blind source separation (BSS),in which the pre-whitening procedure of the observed signals plays an important role.Usually,principle component analysis (PCA) is employed for this preprocessing task.In practice,the observed signals of a passive radar system are usually corrupted by strong noise and outliers,which greatly reduces the performance of BSS methods.However,this problem is rarely taken into account in the whitening step of traditional BSS methods.We focus on this problem and propose a new whitening framework for noisy BSS.The idea is that the noise variance is removed from the covariance matrix of the observed signals before whitening.The experiments show that the BSS performance is greatly improved using the proposed whitening framework.关键词：independent component analysis (ICA);blind source separation (BSS);pre-whitening;passive radar system;weak signal extraction2|1353|7更新时间：2025-07-16
- 摘要：To resolve the problem of 2D ISAR imaging of rotating micro-motion targets,firstly,this paper analysis the range-slow-time echo characteristics of rotating micro-motion and rigid parts.The Sine-Demodulation RWT based imaging algorithm for rotating micro-motion parts is proposed.The position parameters of rotating micro-motion scatters are estimated and their echoes are removed.The remained echoes,based on RWT,are used to reconstruct the rigid signals and ISAR imaging for rigid parts is performed by RD algorithm.Finally,simulation results have proved the validity of the proposed algorithm.关键词：inverse synthetic aperture radar(ISAR);micro-motion target imaging;Radon-Wigner transformation(RWT)2|1054|5更新时间：2025-07-16
- 摘要：The space-borne polarimetric interferometric synthetic aperture radar (POLinSAR) working at UHF/VHF,P and L bands are sensitive to the ionospheric effects such as phase perturbation,Faraday rotation,etc.which will cause POLinSAR system performance deterioration in imaging and geophysical parameter inversion.This paper analyzed the image defocusing and polarization rotation decorrelation induced by ionospheric irregularities and Faraday rotation.In addition,simulations with typical system parameters and ionosphere conditions were analyzed.The results show that the ionospheric effects can both introduce decorrelations and limit the polarimetric vector space of POLinSAR systems on coherence optimization which affect POLinSAR applications significantly.关键词：ionosphere;decorrelation;Faraday rotation;ionospheric irregularities2|1536|3更新时间：2025-07-16
- 摘要：This paper introduces the problem of virtual network mapping on network virtualization technology,reviews the previous studies and analyzes the shortage of existing mapping algorithms.A new mapping algorithm PBMC is proposed,which is based on path based multi-commodity problem model to resolve the problem of hop count limit and network resource distribution balance.Simulation results indicate that compared with traditional multi-commodity based algorithm,PBMC performs better in virtual network request acceptance ratio and resource utilization ratio.关键词：network virtualization;virtual network;mapping algorithm;multi-commodity problem2|1512|9更新时间：2025-07-16
- 摘要：A novel robust space-time adaptive processing (STAP) method is proposed to eliminate clutter in airborne radar with conformal antennas array.This method filters the target information of range cell under test based on the phase characteristic of target.Then the clutter characteristic are described by constructing AR model and the subspace,which is orthogonal to the clutter and jamming space,is obtained to eliminate clutter.Compared with conventional Doppler compensation methods,direct data domain methods and parametric methods,the proposed method is more robust because its performance can’t be influenced by radar working mode and outliers,and it can be applied for arbitrary array.The simulation results demonstrate its effectiveness.关键词：space-time adaptive processing;conformal antennas array;AR model;clutter suppression2|1663|5更新时间：2025-07-16
- 摘要：Hybrid filtering algorithm based on triangle modulus operator makes fusion decision about the boundary point,and performs hybrid filtering based on the fusion results.Accordingly,this algorithm improves performance of hybrid filter.However,there is an inevitable shortcoming in this hybrid filtering algorithm,which implements filtering at pixel domain only with single liner or nonlinear filtering,while it makes fusion decision about the boundary point.In this paper,in order to overcome the shortcoming,a new fusion filter algorithm based on triangle modulus fusion operator was proposed.The proposed algorithm improves filter performance with information fusion.The experiment results show the validity of this new algorithm.Moreover,the proposed algorithm provides a novel approach to image filter technology.关键词：triangle module criterion;hybrid filtering;fusion filtering2|1014|0更新时间：2025-07-16
- 摘要：Most economical service-oriented flows calculation mechanism is introduced during structure learning for dynamic Bayesian networks and a coordination decomposing model for service flows oriented dynamic bayesian network (SFO-DBNs) is presented.In this model,a complex flow-calculation for large system may be dynamically decomposed into several sub-service flows that can be respectively modeling,which extends algorithm Ford-Fulkerson to multi-sources and multi-sinks and joins the time slice t factors on the service flow stability constraint.Simulating for digital gas fields pipe-net emergent scheduling plan and pick-convey balance analysis illustrate that the method of SFO-DBNs is effective and efficient.关键词：dynamic Bayesian networks;digital gas field;service-oriented flow5|1143|1更新时间：2025-07-16
- 摘要：Prof.Ye Dongyi has pointed out in his paper that the reduction approach proposed by Hu Xiaohua et al.will lead to wrong results under some circumstances.In this paper,we find out through analysis that Ye’s approach is actually positive region reduction,whereas Hu’s approach is to make sure that the boundary regions are kept unchanged.The main difference between the two approaches is that each use a different standard,thus there is no ground to judge which one is correct or wrong.What is more,we clarify the relationship among various reduction standards for decision table,and we also give the relationship between reduction results when there is a strong-week correlation between two reduction standards.关键词：rough set;decision table;reduction standard;discernibility function2|1020|2更新时间：2025-07-16
- 摘要：A novel method related to diffraction tomography is presented for imaging two-dimensional weak-scattering objects embedded in a lossy background with phaseless data.The proposed method requires only intensity measurements.Based on the information of the total field magnitudes the pseudo Fourier transformation of the object function can be determined,which is distributed along a fixed arc in the complex space.After expanding the object function by Fourier series the pseudo Fourier spectrum can be represented by the Fourier coefficients,which can be written in a form of system of equations.By means of regularization the ill-posed matrix can be solved and the object function is reconstructed.Numerical simulation results presented have proven the validity of the proposed method.Since this reconstruction algorithm needs only intensity information to rebuild the geometric and electromagnetic properties of objects embedded in a lossy background,it circumvents the difficulty of direct phase measurement.关键词：electromagnetic inverse scattering;DT (diffraction tomography);lossy background;phase-less measurements;weak scattering2|874|0更新时间：2025-07-16
- 摘要：Considering from the law of gravity,the influence between particles includes distance and direction.After discussing the vector influence between data objects,it is applied in clustering algorithm.Vector influence function is presented from the scalar influence function and direction influence function.Two methods—similarity and sum are introduced to compute the direction influence.The algorithm deals with the core point by getting the projection of the points in its neighborhood to judge whether it is uniformity influence.Only uniformity influence points can be expanded to form clusters.The theoretical analysis and experimental results indicate that the algorithm can discover clusters with arbitrary shape and can effectively eliminate noise such as boundary sparse points.It solves the difficulties of clustering high dimensional spatial data such as the spatial distribution of the data,not obvious boundary between clusters,too many noise data points and the phenomenon that the distance between the nearest and farthest neighbors of a data point goes to zero etc.The algorithm improves the accuracy of clustering and offers better results of clustering on various data sets.It executes effectively and efficiently.The algorithm is scalable and general.While transforming the semi-structure data into Euclid space,it will always appear boundary sparse objects,VICA can deal with the noise effectively.Therefore,the algorithm is proper with the high dimension data set,and also can be applied in the semi-structure data clustering.关键词：vector influence;clustering;projection points;sparse influence points;uniformity influence neighborhood2|975|0更新时间：2025-07-16
- 摘要：This paper proposes a new method for estimating the direction-of-arrival (DOA) of wideband signal,which employs particle filters to track array manifold at different frequency bands.Compared with the coherent signal-subspace method (CSM),the proposed method utilizes the current observed data and does not require the estimated covariance matrix,thus it performs better while considering a small sample set.In the meantime,this method does not require the preliminary DOA estimates.Moreover,the proposed method can localize completely correlated sources as it is based on the idea of maximum likelihood.Simulation results show that the performance of the propose method is better than CSM when the sample set is small,the signal to noise ratio (SNR) is low and the signal sources are correlated.关键词：wideband signal;particle filters;DOA estimation;CSM3|1051|4更新时间：2025-07-16
- 摘要：The derivation mistake of clustering center and the related wrong conclusion in Gao’s fuzzy maximum scatter difference discriminant criterion based clustering algorithm (FMSDCA) are pointed out.A new clustering algorithm based on fuzzy maximum scatter difference discriminant criterion (FMSDC),called as fuzzy compactness and separation clustering algorithm based on fuzzy maximum scatter difference discriminant criterion (FMSDC-FCS),is proposed.FMSDC-FCS make use of the FMSDC to generate optimal projection vector and make use of the fuzzy compactness and separation (FCS) algorithm to cluster the reduced-dimensional data set.The projection vector and clustering result are optimized by alternately running FMSDC in the original data space and FCS in the projection space,and the original data is clustered by clustering the reduced-dimensional data.The experimental results demonstrate that the overall performance of FMSDC-FCS surpasses that of original FCS algorithm,FMSDCA and classical fuzzy c-means algorithm.关键词：fuzzy clustering;fuzzy maximum scatter difference discriminant criterion;feature extraction;fuzzy compact and separation algorithm2|1236|1更新时间：2025-07-16
- 摘要：A new method is introduced for designing microstrip dual-mode bandpass filters by using different notch positions.By using this method,dual-mode bandpass filter with a pair of transmission zeros or with no transmission zeros can be realized.After analyzing the influence of the notch position to the dual modes in the resonator,the topology structure of the dual mode filter is established.Using full-wave EM software,two kinds of filters with center frequency of 2.05GHz and bandwidth of 100MHz are designed based on different notch positions.Both simulated and measured results are in good agreement.关键词：bandpass filter;dual mode resonator;coupling matrix2|1008|2更新时间：2025-07-16
- 摘要：Due to suppression the influence of impulsive noise spikes (outliers) from desired signal direction of arrival in GPS signals,the Householder multistage wiener filter is improved,and the sample selected Householder multistage wiener filter is proposed.The enhanced algorithm is adopted in space-time anti-jamming processing in GPS receiver.The method has the ability of avoiding the influence of impulsive noise spikes (outliers) to weights calculation,and to the desired signal waveform.Simulation results indicate the algorithm achieves favorable anti-jamming performance.关键词：array signal processing;global positioning system(GPS);low complexity;anti-jamming(AJ);space-time(ST)2|1329|2更新时间：2025-07-16
- 摘要：Based on the basic mechanism and characteristics,the development history and current status of skywave over-the-horizon radar has been addressed.Due to the military requirement and hotspot in the new era,the situation and functions of skywave radar in strategic warning system has been illuminated,including air defense,anti-missile and surface surveillance.In research fields such as system design,signal processing and data processing,the research trends and key techniques have been reviewed.Current research interests and hotspots in skywave radar have been proposed and some technical approaches have been discussed.Finally the development of skywave over-the-horizon radar has been prospects.关键词：skywave over-the-horizon radar;strategic warning;air defense and anti-missile warning;anti-stealth6|5745|41更新时间：2025-07-16
- 摘要：LOO (Leave One Out) is commonly used to evaluate the generalization performance of an SVM (Support Vector Machine),the disadvantage of which is time consuming.In order to decrease the time cost,several LOO bounds are proposed.The most famous bounds are Joachims bound and Jaakkola-Haussler bound.Based on the two bounds,the generalization performance of an SVM can be evaluated properly with decreased time cost.This paper gives the proof of the equivalence of the two bounds in an SVM with RBF (Radial Basis Function) kernel,analyzes the two bounds theoretically,proposes an advanced Joachims bound,compares the LOO error,Joachims bound,Jaakkola-Haussler bound and the advanced Joachims bound by simulated experiments.Results show that the advanced Joachims bound is closer to the LOO error,and is a better method to evaluate the generalization performance of an SVM.关键词：support vector machine;radial basis function kernel;evaluation of the generalization performance;advanced Joachims bound2|1130|1更新时间：2025-07-16
- 摘要：The relationship between the rows of Walsh and m sequence matrix is presented depending on the polynomial produce phase shift of m sequence.By using a mapping relation between Gold sequences and Walsh sequences,a fast algorithm is proposed to deal with the problems lying in fast correlation of Gold sequence.The algorithm utilizes the shift accumulator to reduce the computation cost.A consecutive frame correlation method is investigated to solve the influence of data bit transition on correlation.A multi-satellite code acquisition method is presented according to the characteristic of the GPS C/A codes,which reduces the calculation operation of the subsequent satellite acquisition based on the acquisition result of the first satellite code.关键词：acquisition;fast walsh transform;GPS C/A code2|1147|4更新时间：2025-07-16
- 摘要：Space-time adaptive processing (STAP) is an effective tool for detecting moving target in airborne radar system.However,in actual clutter environment,the performance of conventional STAP algorithms will degrade a lot for lacking sufficient independent identically distributed training samples.By exploiting the intrinsic sparsity of the clutter distribution in the angle-Doppler domain,an algorithm called SR-STAP is proposed to obtain super-resolution space-time spectrum as well as the clutter covariance matrix with much less training samples.The results of both Mountaintop real data and simulations have proved that SR-STAP can obtain fast convergence rate and achieve better clutter suppression performance than conventional method in actual clutter scenario.关键词：space-time adaptive processing;low sample support;sparse recovery3|1488|23更新时间：2025-07-16
- 摘要：The paper presents an improved adaptive interference cancellation algorithm filtering nonstationary random signal.The complex electromagnetic radiation signal is decomposed to some signals with different frequency by the Empirical Mode Decomposition(EMD) method.An improved least mean square(LMS) algorithm is applied to the adaptive interference cancellation.Computer simulation and experimental results show that the method has better noise cancellation capability than the traditional adaptive noise cancellation.At the same time,the adaptive interference cancellation improves the speed and precision of electromagnetic radiation measurement.So it can be introduced to the engineering application.关键词：electromagnetic radiation measurement;empirical mode decomposition;adaptive interference cancellation;least mean square;filtering2|1899|5更新时间：2025-07-16
- 摘要：This paper describes how to construct a class specific hyper-graph (CSHG) model from a large corpus of multi-view images using local invariant features and their spatial configuration.As the first step of this method,each image is represented with a graph,which is constructed from a group of selected robust SIFT features.Secondly,a similarity propagation based graph clustering (SPGC) method is then proposed.Using this clustering method,the positive example graphs of a specific class accompanied with a set of negative example graphs are clustered into one or more clusters,which minimize an entropy function with a restriction defined on the F-measure.Based on SPGC and the rules of minimizing an entropy function,each cluster is simplified into a tree structure composed of a series of irreducible graphs.Finally,a recognition oriented class specific hyper-graph is generated from the given graph set.Using a trained CSHG model,object recognition can be implemented.Experimental results demonstrate the scalability and recognition performance of the method.关键词：object recognition;class specific hyper graph;attributed graph;local invariant feature;SIFT(Scale Invariant Feature Transform)2|952|2更新时间：2025-07-16
- 摘要：As a representative of hierarchy-based protocol in wireless sensor network,LEACH is an elegant solution for energy efficiency.However,LEACH still has some deficiencies such as the great cluster and small cluster coexist;unreasonable cluster head selection while the nodes have different energy;the node still consumes energy after the death of the cluster head.We propose a new energy-efficient LEACH-based protocol that employed cluster member threshold and merged the tiny cluster to avoid the great cluster and small cluster existing at the same time;estimated cluster head’s energy to reduce unnecessary energy consumption.Analysis and simulation results show that our proposed algorithm provides more uniform energy consumption among nodes and can prolong network lifetime compared to LEACH.关键词：wireless sensor network;great cluster;small cluster;cluster member threshold;energy estimate2|2130|18更新时间：2025-07-16
- 摘要：For different signal structures,the degradation of tracking performance caused by CWI (continuous wave interference) is different.The traditional analyses and the corresponding results are obtained with the assumption that the CWI complies with the Gaussian distribution and the effect of PRN (Pseudo-Random Noise) on performance is ignored.With the consideration of the effect of discrete spectrum line of PRN code,the expression of the maximum code tracking error of the non-coherent early-minus-late power discriminator for infinite front-end bandwidth case under CWI is provided and the validation of the expression by computer simulation is performed.The maximum tracking error,average tracking error,and relative tracking error are used to evaluate the anti CWI performance of the GNSS (global navigation satellite system) signal.The comparison of the tracking performance between the coherent early-minus-late and the non-coherent early-minus-late power discriminators under CWI shows that their performance difference is obvious under low signal-to-interference ratio and the performance difference depends on the modulation types.At last,the evaluation of the anti CWI performance among all GPS C/A codes and the comparison of the performance among BPSK(1),BOC(1,1),and MBOC(6,1,1/11) under CWI are performed,respectively.关键词：global positioning system;signal structure;error analysis;continuous wave interference;non-coherent delay lock loop;code tracking error3|1922|14更新时间：2025-07-16
- 摘要：An iterative attitude estimation algorithm was proposed to solve multiplicative stochastic matrix in satellite attitude determination system.Based on the principle of linear minimum-variance and projection formula,the attitude iterative filter algorithm was deduced.By linearizing and iterating two times respectively for state equation and measure equation,the algorithm can reduce the influence of linearization error to the attitude determination precision.The algorithm enlarges the application range of EKF in the state estimation of nonlinear systems with multiplicative noise.Simulation results indicate that the proposed algorithm provides effective performance in the presence of multiplicative stochastic matrix.关键词：multiplicative noise;nonlinear system;EKF (extended Kalman filter);particle filter;attitude determination2|1512|5更新时间：2025-07-16
- 摘要：Based on the structural characters of printed circuit board (PCB),a topology optimization model of PCB structure is established.The model consists of two parts,i.e.the supporting part and the PCB component part.The supporting part is simulated by elastic material with no mass,while the PCB component part is refined by condensation method of degree of freedom to reduce computation amount.Based on the model,the sensitivity coefficient for element removal is derived by evolutionary structural optimization (ESO) algorithm,and then an ANSYS-based computational method is presented.Meanwhile,the influence of stiffness of support material on the maximal frequency of structure is studied.In the end,a typical case is illustrated as an optimization example,which demonstrates that the optimization method is reasonable and effective in engineering projects.关键词：method of substructure;PCB (Printed Circuit Board) component;condensation of degree of freedom;natural frequency;supporting position layout optimization2|1436|1更新时间：2025-07-16
- 摘要：A novel estimation technique of DOA of multiple waves incident on antenna array is proposed in this paper.This technique can resolve the problem that the number of signals cannot be more than the number of array elements that MUSIC and ESPRIT algorithms meet.With this technique,computational burden is reduced and accuracy is increased.It is suitable for antenna array of any geometry.At same time,signal frequency estimation is obtained and automatically paired 2-D estimation is also obtained for plane array.By use of responding techniques,estimating DOA of correlated signal sources is done.This paper takes an example of estimating 2-D angle (elevation and azimuth) of multiple plane waves of more than number of array elements incident on uniform circular array (UCA) and simulates.Finally,computer simulation result is given to confirm its practicability and effectiveness.关键词：DOA;spectrum estimation;uniform circular array(UCA);ESPRIT3|1263|2更新时间：2025-07-16
- 摘要：Considering surface’s random error and systematic error of reflector antenna,the difference of both errors is discussed by comparing Ruze formula,best-fit paraboloid and mechanical-electromagnetic-field coupling model.Since the deformation error is not concerned in Ruze formula,reflector’s precision is required too high sometimes so that the difficulty of antenna’s design and manufacturing is increased considerably.In contrast,the precision of the reflector required by the developed coupling model could be decreased.For the same surface precision,the higher electronic performance could be obtained by the coupling model than by Ruze formula.The experimental results of three antennas respectively are given to demonstrate the difference between them.In addition,the coupling model also paves a road for realization of mechatronics design of reflector antenna in engineering.关键词：reflector antenna;random error;systematic error;Ruze formula;coupling model2|1560|5更新时间：2025-07-16
- 摘要：This paper presents a constrained multi-objective particle swarm optimization algorithm with few control parameters to solve constrained multi-objective optimization problems.In this algorithm,a Gaussian distribution based on the global/local best positions is developed to update the particles’ positions.It makes unnecessary to perform fine tuning on such control parameters as inertia weight and acceleration coefficients.Using an infeasible archive to save infeasible solutions,an improved update method of the infeasible archive is proposed.In order to balance the algorithm’s capabilities to exploit known feasible regions and to explore unknown feasible regions,a linear decreasing strategy is introduced to assign the probability,based on which the particles select their global best positions from the infeasible archive.Finally,feasibility of the proposed algorithm is validated by simulation results.关键词：multi-objective optimization;constraint;particle swarm optimization;Gaussian distribution2|1434|10更新时间：2025-07-16
- 摘要：In order to classify the target samples of diverse importance much more precisely according to the predefined importance of samples in antimissile system,a technique for target recognition based on intuitionistic fuzzy kernel matching pursuit (IFKMP) is proposed.With the help of the advantages of kernel matching pursuit (KMP) and least-squares loss function,intuitionistic fuzzy kernel matching pursuit learning machine (IFKMPLM) is devised and built based on least-squares loss function,which is expanded to any non-squares loss function,following with IFKMPLM based on that build.Ascribing to transforming intuitionistic fuzzy parameter into a renewed form of intuitionistic fuzzy function,the algorithm for ascertaining intuitionistic fuzzy function is also presented,serving for the appointed important target samples possessing much more precise.An extensive experimental comparison among KMP,FKMP,and IFKMP performed on linear and homocentric circle samples,respectively,shows its superiority over others,moreover,the recognition results of the practical target samples prove the high efficiency of the proposed technique.关键词：target recognition;kernel matching pursuit;intuitionistic fuzzy sets;loss function2|1445|16更新时间：2025-07-16
- 摘要：We propose an improved model that changes those parameters by Kullback-Leibler(KL) distance and global region by local neighborhood near the curve.Validation is implemented by experiments on mass clinical images.Take manual segmentation by a medical expert as a standard,we show that the new model improves the segmentation results compared to traditional CV model.The function has better convergence speed and stability.关键词：Chen-Vese(CV) model;Kullback-Leibler(KL) distance;local neighborhood information;medical image segmentation2|1352|6更新时间：2025-07-16
- 摘要：This paper presents a miniaturized wideband DSPSL hybrid coupler with phase inverter;the open-stubs are also introduced to further reduce the size of the hybrid coupler.The design strategies and procedures of the hybrid coupler are presented at first.A prototype operating at 1GHz is fabricated for verification.The experimental results show that the size of the proposed hybrid is reduced to 11% of the conventional hybrid coupler.The relative operating bandwidth is greater than 80%,return loss at the central operating frequency is less than -20dB,while the isolation is less than -30dB.关键词：hybrid coupler;wideband;phase inverter;double-sided parallel strip line (DSPSL)2|1006|3更新时间：2025-07-16
- 摘要：Low-rate denial of service(LDoS)is a new class of DoS attack,which exploits the deficiencies of the minimum RTO of TCP to send out attack packets about 10%-20% of normal traffic in short periodic pulses to a victim.It is hard to be detected through traditional detection mechanism.In this paper,an approach of detecting LDoS attack based on the model of small signal is proposed.The proposed approach takes statistics on the packets arriving in 30 seconds (sampling time is 10ms,total of 3000 sampling points),and compares the statistical result with the characteristic judging value,which is settled as a threshold to indicate the difference between normal and attack flow.An eigenvalue-estimating matrix is established to estimate the attack period after LDoS attack being detected.Simulation results in NS-2 environment show that the proposed approach can detect the LDoS attack effectively.关键词：low-rate denial of service (LDoS);small signal;detection;multiple sampling averaging based on missing sampling (MSABMS)2|1280|6更新时间：2025-07-16
- 摘要：The isolation between the transmitted signal and the reception one of SAR(Synthetic Aperture Radar) jammer is a bottleneck for many DRFM(Digital Radio Frequency Memory) based jammers.This problem is especially important for SAR azimuth deceptive jamming and also for measures against waveform agile SAR ECCM(Electronic Counter-Counter Measures) where SAR jammers need to receive and transmit signal simultaneously within the same pulse.In order to get the jammer’s coupling signal model caused by isolation problem,the mathematical series are employed to describe the specific working process of SAR jammer.Considering the LFM(Linear Frequency Modulation) signal’s time-frequency property and its non-ideal waveform in real application,a method to decouple LFM’s time-frequency coupling and also to compensate the non-ideal waveform is proposed here,which makes the harmful trans-reception coupling component and the useful received signal much easier to be distinguished.This suggests that the jammer’s trans-reception isolation problem can be solved in a much easier way now by only employing filtering and other signal processing technologies.Finally,our method is proved both by the simulation and the data analysis to be effective.关键词：SAR(Synthetic Aperture Radar);isolation;LFM(Linear Frequency Modulation);time-frequency characteristics2|1397|1更新时间：2025-07-16
- 摘要：The impact of time synchronization errors on the spaceborne/airborne hybrid bistatic SAR (SA-BSAR) is analyzed on the basis of several existing results applied to the spaceborne bistatic SAR or the airborne bistatic SAR.Quantitative error analysis,uniquely for the SA-BSAR system,is performed using an existing model for time synchronization errors.Several simulation experiments were carried out and the results indicate that in the SA-BSAR system,taking the practical accuracy and stability of the current oscillator into consideration,the impact of the pulse repetition frequency (PRF) jitter is trivial and the linear time synchronization error is proved to be the major error source.At last,the requirement on the residual errors is derived.关键词：bistatic synthetic aperture radar (BSAR);spaceborne/airborne hybrid bistatic SAR (SA-BSAR);time synchronization errors;error analysis2|1328|4更新时间：2025-07-16
- 摘要：In order to meet the acquisition requirement of aerospace spread spectrum TT&C system,a FFT-based code acquisition method was proposed which could reduce the spectrum peak degradation and get high frequency estimation accuracy.It integrated the data weighted by hanning window in the partial matched filter to reduce the spectrum peak degradation.Interpolated FFT was adopted to estimate the Doppler frequency in order to enhance the frequency estimation accuracy.According to the acquisition characteristics in different TT&C conditions,two interpolation methods such as parabolic interpolation and improved Rife were analyzed.Both analysis and simulation demonstrate that the proposed method can reduce the spectrum peak degradation and improve the Doppler frequency estimation accuracy.2|1783|8更新时间：2025-07-16
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