最新刊期
卷 ， 期 6 ， 1999
- 摘要：Two tracking techniques-Track-While-Scan and Track-and Search are studied from the aspet of basic concepts and the performance prediction in this paper. The similarities and differences of these two techniques in phased array radar and of track-while-scan technique in phased array radar and mechanical scanning radar are compared. The methods to calculate the performance index of the two techniques in phased array radar are proposed, including accuracy, target capacity,utilization rate of rare and reaction time. The performance of the two techniques is compared.关键词：Track-while-scan;Track-and-search;phased array radar;Mechanical scanning radar2|774|5更新时间：2025-12-08
- 摘要：In this paper,procedure of the absolute calibration of radar scatterometer is presented. Effects of the far field criterion for the calibration are analyzed. After converting the effect of curvature of spherical wavefront and the amplitude and phase nonuniformity of the incident field to the variation of the radar cross section, the concept of effective radar cross section （ERCS） is introduced to unify the calibration formula for near field region and far field region measurement, Using the new formula,a practical near field region absolute calibration scheme is proposed. Absolute calibrations of four scatterometers of S,C,X and Ku band show the validity of the given method.关键词：scatterometer;Absolute Calibration;Far Field Criterion;Near Field Region2|143|2更新时间：2025-12-08
- 摘要：When a current loop rounding on a multicylindrically layered mandrel is located in multicicular media, the expressions of eletromagnetic fields are derived analytically. The dielectric constants, conductivities and permeabilities of the mandrel and the media are taken into account simultaneously so the formulae are of universal significance. Solutions of the fields are expressed as some generalized integrals whose integrands contain Bessel functions with complex arguments. When the conductivity of the mandrel is replaced by zero in the programme, the electromagnetic fields of a loop rounding on an insulated mandrel can be calculated whose differences contrasted with that of a point magneitc dipole are generally less than 1%.In such way, the reliability of the expressions and the algorithm has been examined. Finally, the influence of a metallic mandrel has been discussed.关键词：Current loop;Mandrel;Multicircularly layeral medium;electromagnetic field2|78|1更新时间：2025-12-08
- 摘要：A method for real-time reconstruction of the beam spot profiles in the shadow mask CRT is proud in this paper. The deflection system that provides the micro tranSlation for the spot reconstruction is described in detail. The method for calibrating the deflection sensitivity is the provided. The original beam spot profile that is separated by the shadoW mask is obtained from the masked beam spot on the screen.关键词：CRT （Cathode ray tube）;Shadow Mask CRT;The Measurement of Beam Profiel （the Resolution Measurement）2|34|1更新时间：2025-12-08
- 摘要：The equation of electron space trajectory in drifting tube filled with on plasma is given in this paper. The space is divided into three areas; the equation is numerically solved under relativistic and unelativistic condition; the transmission properties are studied and some parameters affecting the transmission properties are discussed in detail. The study shows that efficient transmission of magntically Self-focussing beam can be reached by choosing the plasma filling factor and the voltage.关键词：Magnetically Self-focussing;electron beam;plasma;Space trajectory;Transmission2|74|3更新时间：2025-12-08
- 摘要：Spatial resolution improvement of digital images has significant applications in remote sensing and computer vision. Some former algorithms were （or supposed to be） almost for multiframe images of same spatial resolution and without geometric distortion. In this paper, a general method of interpolation and simulated sampling for spatial resolution improvement from multiframes of undersampled digital images is proposed based on the iterative metheds for signal reconstruction fain nonuniform sampling and the methods of projection onto convex sets （POCS）. The method can tackle multiframe images of various spatial resolutions,different image radiance, ralative geometric distortion, additive random noise, and so on. An idea of varying weights in iteration of parallel POCS methods is also discussed. Some experiments with resolution test pattern and multiangular remote sensing images show the convergence and effectiveness of the algorithms.关键词：Projection onto Convex Sets （POCS） method;Bandlimited signal reconstruction;Signal temporal resolution;Spatial resolution;Spatial resolution improvement2|225|1更新时间：2025-12-08
- 摘要：Chua’s chaotic synchronized system and its main properties are investigated and a multistage chaotic synchronized system for secure communication is proposed. It is shown that the message signal hidden in chaotic drier of the system can be perfectly reconstructed, and the bandwidth, the characteristic of distortion, and the level of security are improved. Examples of speech and still image communication are presented by using the system. level of security are improved.Examples of speech and still image communication are presented by using the system.关键词：Chaotic synchronized system;Chua’s system;Perfect reconstruction;secure communication2|208|4更新时间：2025-12-08
- 摘要：By definition,for targets located in a spherically stratified （horizontally homogeneous） lower atmosphere or ionosphere, this paper derives the residual error medels[Formulae （14） and （20）; （24） and （27）; （57） and （59）, （63） and （65）] of elevation angle refraction errors, range refraction errors and range rate refraction errors corresponding to monopulse radar and trilateration radar. In comparison with existing models, the derived models possess higher accuracy, are applicable to high and low elevation angles and targets located in lower atmosphere and ionosphere, have no restriction of range, do not involve the problem of apparent elevation angle rate and are convenient in practice.关键词：Atmospheric refraction error;Residual error model2|197|2更新时间：2025-12-08
- 摘要：In this paper,Cameron correction algorithm on target’s polarization scattering matrix is studied in connection with radar target’s reciprocity correction. The optimization of this algorithm is proved in a quite broad sense.关键词：target;polarization scattering matrix;correction on reciprocity2|71|2更新时间：2025-12-08
- 摘要：An approach to blind adaptive beamforming is presented based on the property of Doppler signals. The weights of the beamformer are Selected according to a new optimization Objective, which consists of minimizing the mean square error between the array output and a unit complex exponential. It is demonstrated via analysis and simulations that this method is close to MVDR with array manifold known exactly, which has maximum SINR, and has the advantage of small computation and rapid convergence rate.关键词：Blind adaptive beamforming;adaptive signal processing;Phased array doppler radar2|199|5更新时间：2025-12-08
- 摘要：This paper studies the three-aperture interferometic synthetic aperture radar （INSAR） detecting and imaging processing technique of the moving groUnd targets, which uses three-port clutter suppression interferometry （CSI） processing to cancel ground clutter, to detect the moving ground targets and simultaneously determine their true azimuth location and radial ground speed and to form the focus moving ground targets’ images. This paper describes in detail the principle of the three-port clutter suppresion interferometry processing, studies the approach to detect the moving ground targets and determine the true azimuth location and radial ground speed and presents a kind of method using INSAR to form the focus moving ground targets’ images. Finally, some typical computer simulation results are presented, which illustrate this technique’s availability.关键词：INSAR technology;Detecting of moving targets;Imaging of moving targets2|311|9更新时间：2025-12-08
- 摘要：The obtaining of velocity vector of the targets by using the distances and the Doppler speeds in multi-radar system is discussed in this paper, and the precision of velocity vector is analyzed. Finally the paper points out that the velocity vector has an important role in tracking maneuvering targets.关键词：Multiple site rdar system;Velocity vector;Error disassembling;target tracking2|163|2更新时间：2025-12-08
- 摘要：A study has been made on near-field effect of extended target scattering in ground-bed active microwave remote sensing. The analysis is started from path-different-only coherent scattering case. The results show the predicted Fresnel zone interfering phenomenon. This somewhat explains why different measurement results may occur from different platform altitudes. Based on this analysis,we introduced the semi-rough scattering concept to cover more general practical cases.Results of this study may be a foundation for sensors calibration and ground-based accurate measurement in case of coherent extended targets.关键词：Microwave remote sensing;Near-field effect;Fresnel zone2|112|1更新时间：2025-12-08
- 摘要：This paper studies a multi-channel synthesis pulse compression method of an UWB radar based on intersection of frequency spectrum,and analyzes its performance in detail. This method effectively solves the problem of direct A/D conversion of the UWB radar signals up to several GHz.Compared with the existing methods, it can be applied to not only LFM signals but also non-inear frequency modulation signals.关键词：pulse compression;Intersection of frequency spectrum;Polynomial interpolation;Delay resolution constant2|434|7更新时间：2025-12-08
- 摘要：The defects classification and their forming processes of TFT-LCDs are analysed. Short tester.open tester and display tester are developed. The laser repair technique and redundant technique are described. An addition repair process using subtraction laser repair system is developed.关键词：Active matrix liquid cyrstal display;Defect test;Laser repair;Redundant technique2|121|3更新时间：2025-12-08
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The Dispersion Characteristics of a New Type Helical Circular-Arc-Chaped Grooved Slow-Wave Structure
摘要：The belieal circular-arc-shaped groovd structure, a new type slow-wave system for high power TWT, is presented in this paper,and the dispersion equation of this circuit is obtained by means of an approximate field theory. The dispersion characteristics of the fundamental wave are discussed and the influence of various circuit parameters on dispersion relations is also investigated. The results of the numerical calculation show that it is very useful for improving the bandwidth by diminishing the pitch angle or increasing the arc angle. The present analysis will be helpful on further study and design of this kind RF system used in high power TWT.关键词：High power TWT;Helical circular-arc-shaped groove slow wave structure;dispersion characteristics2|57|1更新时间：2025-12-08 - 摘要：In this paper a millimeter wave active cylindrical conformable microstrip array antennas at ka band is proposed, which integrate the oscillators and the antenna-fed systems at a single chip. Using FDTD method in the cylindrical coordinates, calculation and theoretical analysis for the system have been executed.关键词：Finite-Difference Time-Domain method （FDTD）;Millimeter wave technique;Active conformal array antenna2|457|1更新时间：2025-12-08
- 摘要：Extracting retinal vessels from the retinal image is important to the diagnosis of hypertension and arteriosclerosis in clinic. This paper presents a method which can segment retinal vessels effectively with a group of nonlinear image processing algorithms. The procedures of the whole operation are: 1 )Adaptive image enhancement with image’s statistic features.2)Adaptive image segment based on blood model. and 3)Extracting vessels’ centerlines via distance transform. The results of .experiment indicate that the method is really suited for non-fluorescence retinal image.关键词：Retinal image;Image segment;Nonlinear image processing2|523|6更新时间：2025-12-08
- 摘要：Piezoelectric ceramics transformer electrostatic field of high voltage effect on the root tip cell of Pisum Sativum L.was tested. In strong electric field case, a potential barrier penetrating model was electal and distortion mechanism of plant cells ware studial in electron level.关键词：Electric field effect;DNA;Potential barrier penetrating2|97|12更新时间：2025-12-08
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- 摘要：Taking Hankel operator as example,this paper studies the sparse matrices of a wide class of integral operators expanded under square and rectangular two-dimensional wavelet bases, respectively. Our conclusions are verified by numerical results obtained.关键词：Integral operators;Hankel operators;Orthonomal wavelet transform2|64|0更新时间：2025-12-08
- 摘要：This paper presents a method for computing K-terminal reliability of RBN, the probability that any two nodes of set K can communicate with each other. Because K-terminal reliability problem of RBN is an NP-hard problem,the existing algorithms are only approximate for general RBN and only accurate for some restricted RBN, and little is known about accurate algorithm for general RBN. This paper, by conjugating with the new reliability-preserving reduction we present and applying pivotal decomposition theorem for some special nodes,presents an effective algorithm for computing K-terminal reliability of RBN.关键词：Radio-broadcast network;reliability;algorithm;Reliability-preserving reduction;Privotal decomposition theorem2|89|1更新时间：2025-12-08
- 摘要：The problem on building context dependent model in continuous mandarin speech recognition in order to avoid coarticulatory effects is descussed in detail in this paper. On the basis of information theory, the distance metric of the traditional clustering algorithm is first studied,which is the divergence of the model distribution and the difference in entropy result from model merging or splitting. Then the clustering algorithm based on decision tree is presented, which makes full use of the phonological rules. The model obtained from it is easy to be generalized, and this method demonstrates especially better when many triphones emerge that are not covered in the training material. In addition, the clustering and training procedure is discussed. At last, the speaker independent large vocabulary continuous speech recognition experiment shows that, if the recognition material is different from the training material, the recognition model obtained from the decision-tree-based clustering algoyithm reduces the error rate by 7. 95 %. However, the recognition model obtained from the traditional merge algorithm reduces the error rate only by 2. 63 %.关键词：continuous speech recognition;Context dependent;decision tree;clustering algorithm2|252|3更新时间：2025-12-08
- 摘要：In this paper we propose a two-stage tandem queue model for a two-link striping system in packetswitched networks. By using the matrix-geometric solution, we derive the avenge packet delay time and the link utilization ratio in exact form. Through the numerical examples, the effects of the link difference, the buffer size, the packet arrival rates,and the input burstiness on key performance measures are discussed.关键词：communication networks;Inverse multiplexing;Dispersion routing;Striping;Bursty arrivals2|53|1更新时间：2025-12-08
- 摘要：This paper, from the characteristics of the mobile satellite ground track, discusses a design method of mobile satellite constellations with common ground track, and also uses the method on the China area design by computer simulation and specialized satellite communication tool. By choosing the satellite orbit period as one fourth of the sidereal day, the eccentricity as 0. 158, the orbital plane inclination as 63 .4 degrees,ouly four satellites with common ground track can cover China mainland almost almos seamlessly,while the average elevation angle is greater than 50 degrees.关键词：Mobile satellite communication;Constellation;Common ground track;Coverage capability2|204|12更新时间：2025-12-08
- 摘要：Recently, there is discrepancy in the impact of LRD （Long-Range-Dependence） on modeling and controlling over ATM. In this paper, the influence of the second-order-statistics of LRD process on queue performance is studied. The influence is controlled by other factors-buffer dimension and utilization. First the result is put forward through simulation experiments and is explained by theoretical analysis. Finally, we give the suggestion and conclusion.关键词：LRD;SRD;VBR vided;Network traffic;autocorrelation2|80|1更新时间：2025-12-08
- 摘要：Because of different operation environmnt, wireess ATM cells for protocols difterent from thase of ATM in BISDN. In this paper we discuss the problems in cell format and cell delineation, the possible soutions to thern are given.关键词：wireless ATM;Cel formt;Cell delineation2|47|4更新时间：2025-12-08
- 摘要：In this paper, a convolutional enceded orthogonal sequence multicode CDMA system is proposed so as to transmit user’s high rate data to fit the requirement of the services of the future mobile communication. Similar to multicarrier modulation, the higher rate date transmitted by serial-to-parallel is converted at first, and then the lower rate data streams are convolutionally encoded and spreaded spectrum modulated by a set of orthogonal sequence Being different from multicarrier modulationg, all lower branch data streams use single carrier. The performance of the system over Nakagami fading channel is calculated, and numerical result is analyzed.关键词：Convolutional encoded;Orthogonal sequence multicode CDMA;Nakagami fading channel2|140|2更新时间：2025-12-08
- 摘要：In this paper, the new efficient methods for precise modeling and numerical analysis of EM scattering from 3-dimensional objects with complex structue-fast multipole method （FMM） and multilevel fast multipole （MLFMA）have been introduced. These methods employ various efficient techiques to reduce the calculation complexity and memory requirement in numerical analysis of EM scattering. The theory of FMM and MLFMA is summarized in this paper. Then some new research results of these methods combined with various efficient techniques are presented. Finally some typical application results and prospects of these methods are introduced briefly.关键词：3-dimensional EM scattering;Efficient numerical method;FMM;Asymptotic expansion2|784|29更新时间：2025-12-08
- 摘要：Following the development of micro/nano science and technology,one of the most important technologies in microfabrication and microanalyses, focused ion beam （FIB） technology, is gaining more interests. In this paper, the main functions of FIB technology with liquid metal ion ires （LMIS） is summarized briefly. Its recent applications in the following regions are reviewed in detail: （1） In integrated semiconductor circuits: integrating devices, failure analysis and repair. （2）In integrated optoelectronic circuits: the fabrication of quantum well laser and phase mask for optical fiber, the research of quantum effeCts. （3）the fabrications of superconductor devices and vacuum microelectronic devices. （4）the technology of secondary ion mass spectrometry and the preparation of specimens for transmission electron microscopy.关键词：Focused ion beam;Liquid metal ion source;Microfabrication;Semicondutor integrated circuit;Photonic and optoelectronic integrated circuit;Micro/nano technology2|209|1更新时间：2025-12-08
- 摘要：A new type of conical ultra-wide hand（UWB） antennas ridged by a novel fin-line ed as radiator and receiver of the short pulse are developed, in which, a new UWB fed structure of coplanar waveguide to fin-line is ed initially.The experimental results show the characteristics of high fidelity, high gain compared with some common wide band antennas such as the biconical antennas, V-conical antennas, log-periodic antennas, and the other TEM horns. By using the developedUWB antenna, an ultra-wide band radar （UWBR） laboratory is set up and some simple square cylindrical conductor objects with and without anted absorbing material in its surface are ed to study the transient characteristics of the pulse reflection. The experimental results show that the developed antenna is a practical UWB antenna in the applications of UWBR.关键词：ultra-wide band;antenna2|114|1更新时间：2025-12-08
- 摘要：A mixer-free all digital quadrature demodulation method based on second-order sampling is proposed. This method makes esecond-order sampling of a bandpass signal directly, and produces quadrature basebands by passing the samples through linear-phase-shifting filters. Mixers are omitted in this method. Compared with the methods based on first-order sampling the method we proposed here has more freedom in the selection of sampling rates.关键词：second-order sampling;Bandpass;IF sampling;Quadrature demodulate;Coherent detection2|257|7更新时间：2025-12-08
- 摘要：In this paper, a nonlinear soft-thresholding method based on orthogonal bases of compactly supported wavelets in frequency domain is proposed to recover signal from transient scattered response contaminated by Gaussian white noise. Two poverties of this kind of wavelet basis are responsible for the effectiveness of the proposed method:one is its compact support in frequency domain, the other is its great capability in data compression. The effectiveness of the proposed method is verified with a synthetic transient scattered response,measured response of a sphere and response of a model aircraft B-58 having the scale ratio of 1: 72 with additive Gaussian noise. The results obtained by the method are compared with those of Fourier truncation, spline smoothing, maximum modulus algorithm of wavelet and nonlinear soft-thresholding based on compactly supported wavelet bases in time domain. The superiority of the proposed method is thus demonstrated.关键词：Orthogonal wavelet bases with compact support in frequency domain;transient scattered response;Nonlinear soft-thresholding;Gaussian white noise2|207|7更新时间：2025-12-08
- 摘要：Iterative method of integral equation is used to de electromagnetic scattering from multiple conducting cylinders in this paper. The fast multipole method （FMM） is used to calculate the interaction between each subscatterer in the iteration process, and it expedites the calculation of matrix-vector multiplication. Meanwhile the biconjugate gradient （BiCG） method instead of the conjugate gradient （CG） method is ed to accelerate the iteration process. The high efficiency of the present method is shown by the numerical results.关键词：Scattering from multi-object;Fast multipole method;Biconjugate gradient2|229|9更新时间：2025-12-08
- 摘要：The structure of the Dry coefficients of a sine wave is analysed. A new accurate frequency estimator for a single sinusoid is proposed by using the information obtained from the phase of the DFT coefficents. Its performance is complemental with Rife algorithm. So that synthetic approach is proposed. The simulation results indicate that this approach is much better than the DFT and some other fast methods at the cost of double FFT which is far less than the MLE in computer time.关键词：frequency estimation;DFT coefficient;Phase information2|1435|35更新时间：2025-12-08
- 摘要：The method of the feature vector extraction of ocean acoustics signals based on the wave structure is presented. Then the structurally adaptive fuzzy-clustering neural network model is applied to design a new classifier for the ocean acoustics signals. The result shows that the presented method of feature vector extraction of ocean acoustics signals and the designed classifier are satisfactory.关键词：Ocean acoustics signals;Wave structure;Structurally adaptive fuzzy-clustering neural network2|462|18更新时间：2025-12-08
- 摘要：High performance CSCW applications（Synchronous distributed CSCW multimedia applications） are most complicated among all kinds of CSCW applications. They require not only multipoint multimedia real-time transmission, but also many control and management issues. ATM network offers many attractive features to multimedia communications, such as flexible bandwidth allocation and QoS control mechanisms. This paper presents a new ATM-based CSCW multimedia group communications architecture in order to effectively exploit all benefits of ATM. The architecture complies with B-ISDN protocol reference model and separates control （signaling）, management and user data platforms. Finally, We introduce the implementation of the CSCW supporting environment based on our architecture.关键词：CSCW;ATM;Group communications;multimedia2|28|1更新时间：2025-12-08
- 摘要：One crucial defense against exposure of private keys is offered by threshold cryptogTaphy where the private key functions are distributed among several parties such that a predetermined nurnber of parties must mperate in order to corrctly perform this operation. An efficient scheme based on peetry which implements （T, N）-threshold RSA cryptosytem is presentetl. In the system, the power to decrypt and to sign is shared by N players such that any subset of T players can collahaate to perform RSA functions, but no subset of fewer than T corrupted players can decrypt a ciphertext of forg a signature.关键词：Threshold cryptogrphy;secret sharing;RSA cryptosystem2|198|2更新时间：2025-12-08
- 摘要：This paper proposes a multilevel key escrow scheme, based on EIGamal public key cryptosystem and multileval secret-sharing protocol, which effectually prevents from subliminal channels attack in "fair public key cryptosystem" and LED （Law Enforcement Decryptor） too much power in [1].关键词：EIGamal public key cryptosystem;Multilevel secret-sharing protocol;key escrow2|59|9更新时间：2025-12-08
- 摘要：This paper proposes three kinds of image process technology based on wavelet transform. First, image data are processed by 2 dimension dispersed wavelet transform. According to the characteristics of high-frequency and low frequency,some other informations are hidden into the two lowest bits of high-frequency,which is called data conceal. Adding harass applies to change lww-frequency so as to disturb quality of restored image. To distingUish image’s true and false, a procession called false prevention is ed to get some eminent sign in high-frenquency by altering some pixels’ value. Because these methods are based on image data processed by wavelet transform, there are approximately no other additional information. So image compression based on wavelet transform also can be used to these processed image.关键词：wavelet transform;Data conceal;Adding harass;False prevention2|89|3更新时间：2025-12-08
- 摘要：In order to transmit high rate data, a MTCM comined with orthogoal sequence multicode CDMA system is proposed. In this paper, the performance of the systern in AWGN channel is calculated, and the results are analyzed and compared.关键词：MTCM;Orthogonal sepuence multicode CDMA;AWGN channel2|35|0更新时间：2025-12-08
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