最新刊期
卷 38 ， 期 3 ， 2010
- 摘要：The semantic properties of logic systems MTL induced by regular implication operators were disscussed, the integral truth degree theory of formulas on [0,1] can be founded in MTL. However, the logic pseudo-metric space defined by the integral similarity degree between formulas cannot always be constructed. Moreover, those logic systems which could construct such pseudo-metric spaces have the same properties, i.e. all the logic operators are continuous in terms of pseudo-metric, then a possible framework about approximate reasoning is formed in those logic systems.关键词：regular implication operator;measurable;integral truth degree;logic pseudo-metric space;continuity of operator2|1090|22更新时间：2025-07-16
- 摘要：In non-Gaussian background ,it is not easy to obtain the radar target likelihood-ratio detection statistics usually. To solve this problem, a radar target likelihood-ratio detection model based on particle filtering is given. And resampling step has been used in the statistics detection based on particle filtering in order to solve the detection performance degressive problem which caused by the inevitable particle degeneracy. Simulation results show that the detection performance has been improved through the using of resampling. By applying the proposed method for the Swerling Case 2 radar targets detection in different clutter models, the efficiency of the given method has been proved.关键词：particle filtering;statistical detection;radar target detection;particle degeneracy;resampling2|1618|4更新时间：2025-07-16
- 摘要：This paper proposed a multi-channel ink jet printer characterization algorithm by printer color gamut partition and subspace color calibration. First, a printer model is created, then spectral redundancy of the high dimensional colorant space and feasibility of gamut space partition is analyzed. After that, gamut partition method is designed to divide the printer’s gamut into several parts and color calibration is done in each partition. Partition reduces the data dimension and eliminates color redundancy. This method has the advantage of wide-use and no limitation to ink channel numbers.
关键词：color management;color characterization;space partition;high fidelity;color gamut2|1690|17更新时间：2025-07-16 - 摘要：X waves may be used in ultrasound imaging to obtain very high frame rate. But the spatial resolution of the image with a linear imaging mode decreases as compared to conventional focused imaging. The nonlinear fields of limited-diffraction X waves are calculated and studied by solving the KZK equation using a time-domain numerical method. The result indicates that the nonlinear fields of broadband and band-limited X waves are both limited-diffraction beams. Moreover, the second harmonic component has narrower mainlobe and lower sidelobes than the fundamental field. Utilizing the second harmonic of X waves in ultrasound imaging, higher spatial resolution would be obtained throughout the entire imaging range. A theoretical analysis verifies the numerical calculation result.关键词：X waves;KZK (Khokhlov-Zabolotskaya-Kuznetsov) equation;second harmonic2|1217|1更新时间：2025-07-16
- 摘要：The combined effects of mutual coupling, gain-phase errors and sensor position errors of an array degrade severely its performance of the direction finding. Aimed at the uniform circular array(UCA), a novel active calibration algorithm for array errors is presented based on the eigenstructure method. The algorithm is given in alternative iterative style, and its target function is built on the properties of signal subspace. It is suitable for the situation when the calibration sources exist at the same time. The necessary condition for uniqueness of the parameter estimation is also given in this paper. The simulation experiments show the effectiveness of the novel algorithm.
关键词：array calibration;mutual coupling;gain-phase errors;sensor position errors;complex symmetric circular Toeplitz matrix2|1777|3更新时间：2025-07-16 - 摘要：By means of emulating human auditory, γ-Tone filter-banks models based on the auditory system in human cochlea are presented. The speech to be detected goes through the γ-Tone filter-banks, thereby multi-dimension eigenvectors are obtained. By PCA (principal component analysis) and DCT (discrete cosine transform), it is yielded to represent a speaker’s γ-Tone coefficients, γ-Tone filter-banks cepstral coefficients respectively and their derivative features as well. Compared to the ordinary Mel-frequency cepstral coefficients, the speaker recognition system presented turns out to have better recognition rate and robustness characteristics.
关键词：speech signal processing;gammatone filter;auditory feature extraction;cepstral coefficients2|1804|22更新时间：2025-07-16 - 摘要：An analytical solution to the problem of two-dimensional scattering by a homogeneous anisotropic elliptic cylinder is derived. With the aid of an integral equation based on a plane wave representation of the field and the series expansions in terms of Mathieu functions, the transmitted fields of the elliptic cylinder and radar cross sections per unit length under a transverse-electric illumination are obtained. Some numerical results are presented, the effect of electric size and material of elliptic cylinders on the radar cross sections is discussed. The data are in agreement with those available as expected when the elliptic cylinder degenerates to a homogeneous anisotropic circular one.
关键词：electromagnetic scattering;elliptic cylinders;homogeneous anisotropic material;Mathieu functions2|1676|8更新时间：2025-07-16 - 摘要：
To address the selfishness issue in Data-driven overlay network (DONet), a selfishness-aware DONet (SA-DONet) is proposed in this paper. SA-DONet allows each node associative with an altruism value for its contributions to peers. Based on the altruism value, segment requesting and sending algorithms are designed to ensure the more altruistic nodes will have more chances to be served. The primary characteristic of our mechanism lies in three aspects. Firstly, SA-DONet can discover the selfish nodes in a decentralized manner and adjust the segment sending and requesting strategy dynamically. Secondly, selfish assessment (altruism value) comes from the node’s history and doesn’t require any extra probe and measuring packets. Lastly, our algorithms remain comparable computing complexity to DONet. Simulation results show that compared with DONet, even with a significant portion of nodes being selfish, SA-DONet can improve the streaming quality of global multicast session with low control overhead.
关键词：altruism value;application-layer multicast;data-driven;distributed algorithm;selfishness2|1022|0更新时间：2025-07-16 - 摘要：System-on-Chip (SoC) task allocation with memory size information can improve the data storage and transfer efficiency. Nowadays, the methods of memory size estimation often adopt the single granularity and run at slow speed. Therefore, the space exploration of multi-granularity task allocation cannot be supported well. For SoC task allocation, this paper proposes a fast, multi-granularity approach of memory size estimation. The approach estimates the memory size at three granularities. The technique of data domain partition is introduced into the time-consuming process of memory size estimation at loop granularity, which greatly accelerates the analysis processing.
关键词：system-on-chip (SOC);task allocation;memory size estimation;polyhedron model2|1254|5更新时间：2025-07-16 - 摘要：The capacity of wireless mesh networks can be significantly improved by multi-channel communications；channel assignment is an important issue in multi-channel Mesh network. We propose a novel distributed channel assignment algorithm CBLA（Cluster-Based Load-Aware）, which takes advantage of both static and dynamic channel assignment approaches. CBLA uses clustering to reduce the complexity of channel assignment problem, estimates the traffic load by low-overhead statistic information of local packets. Adaptive dynamic channel assignment results in a better link load equilibrium. We also introduce a new routing metric, which combines hop count, channel diversity and cluster information together. A detailed performance evaluation shows that CBLA significantly improves aggregated throughput and reduces average packet delay.
关键词：wireless mesh networks;multi-channel;channel assignment;clustering;load-aware2|1134|2更新时间：2025-07-16 - 摘要：The reasons and influence of receive buffer blocking in Concurrent Multipath Transfer (CMT) environment are studied. A modeling method which is suitable for analyzing the throughput of CMT is also proposed. This model can be used to estimate the throughput according to the drop rate, round trip time and other parameters. It considers whether the fast retransmission is applied and the relationship between the size of congestion window and the volumes of receive buffer. Comparing with the simulation results, the model can predict the variation of throughput very well when the parameters of network are changed.
关键词：concurrent multipath transfer;throughput model;receive buffer blocking;round trip time3|1617|4更新时间：2025-07-16 - 摘要：Former DPA(Dynamic Programming Algorithm) has problems of low efficiency in energy accumulation with single point and could not detect entrance target in time. Focus on the problems we improved the DPA in three aspects and applied it in space small target detection. First, the recursive equation was improved to avoid information loss, which caused by manual defocus in the project, by multi-point accumulation. Second, the calculation of multi-velocity plane was simplified as velocity update to reduce the computational complexity. Third, special process was used to solve the problem of entrance targets. The contrastive experiment with real space images proved the validity of our improvements.
关键词：DPA;small targets detection;multi-points accumulation;entrance target.4|1575|7更新时间：2025-07-16 - 摘要：
It is computationally intensive for high frequency algorithms to predict wide band radar signal of large complex targets. A fast novel method combining SBR and EEC techniques with radar signal processing is presented. The fast method gives an order of magnitude speedup in computation time. With the wide radar signal results obtained by this method are presented, to validate the accuracy and efficiency of the fast method.
关键词：radar echo simulation;large time-bandwidth product signal;SBR;EEC2|1679|8更新时间：2025-07-16 - 摘要：This paper presents a multibias optimizing parameter extraction technique for Heterojunction Bipolar Transistor (HBT) small-signal model. The corresponding equations for intrinsic and extrinsic elements have been established in according with small-signal HBT model through formula derivation. A multibias decomposition-based optimization method is discussed. Robustness and accuracy of optimization method are tested on measured S-parameters of GaInP/ GaAs HBT device. Results show that the extracted parameters have the characteristics of exclusive astringency and accuracy with a different set of random starting values, and the relative error between the simulated results and the values measured is less than 1%.
关键词：heterojunction bipolar transistor (HBT);parameter extraction;small-signal equivalent model2|1766|0更新时间：2025-07-16 - 摘要：H-alpha decomposition is modified for dual-polarization SAR data applications. The boundary of the feasible region in H-a plane for dual-polarization cases is derived. It is different from full polarization that the boundary is symmetrical with respect to alpha being 45 derees. Performance of scattering mechanism identification is analyzed using the modified H-a decomposition for HH-VV, HH-HV, and HV-VV SARs, and a feasible division of HH-VV H-alpha plane is obtained. It is demonstrated theoretically that only HH-VV SAR can distinguish three basic scattering mechanisms from an isotropic surface, a dipole, and an isotropic dihedral. Experimental results using real data, acquired by the NASA/JPL AIRSAR and DLR E-SAR, illustrate that eight scattering mechanisms inside the feasible region in H-a plane can be identified on the whole by HH-VV SAR, and only low entropy and high entropy scatterings can be divided by HH-HV and HV-VV SARs.
关键词：polarimetry;synthetic aperture radar (SAR);scattering mechanism;identification2|1120|2更新时间：2025-07-16 - 摘要：
Based on the architecture of a popular parallel platform and properties of extremely large targets, a high-performance parallel multilevel fast multipole algorithm (MLFMA) is proposed and implemented. A detailed description of the proposed parallel MLFMA is presented by a style of multilevel development from a coarser to finer consideration. Along with numerical experiments to analyze numerical performance of each part of the algorithm, the efficiency, accuracy and capability of the parallel MLFMA are well demonstrated. This high-performance parallel MLFMA has successfully computed scatterings by targets with over 310 millions unknowns and more than 2000 wavelengths in sizes.
关键词：multilevel fast multipole algorithm (MLFMA);parallel;scattering2|1804|7更新时间：2025-07-16 - 摘要：The non-linear manifold structure property of inverse synthetic aperture radar (ISAR) images is analysed intensively, and it is pointed that the ISAR images can be viewed as a non-linear manifold of high-dimensional ISAR image space controlled by a few parameters, such as position, attitude and scale. The idea of non-linear manifold learning is introduced into ISAR target recognition, a new feature extraction and recognition method for 2-D ISAR images based on Locality Preserving Projections (LPP) algorithm and k-nearest neighbor classification is proposed. Firstly, the LPP algorithm is used to reduce the dimensionality of the ISAR images, and then four kinds of aircraft target are classified by k-nearest neighbor classification with rejection capability in the low-dimensional subspace. The simulated experiment results suggest that the LPP algorithm has the capability of finding the low-dimensional manifold structure embedded in the high-dimensional ISAR image space, and a higher recognition rate is acquired with the low-dimensional feature obtained by LPP.
关键词：target recognition;ISAR image;non-linear manifold;locality preserving projections2|1809|14更新时间：2025-07-16 - 摘要：In order to solve the premature convergence problem existing in the traditional estimation of distribution algorithm (EDA), based on the analysis of methods for diversity preservation and reasons for premature convergence, an estimation of distribution algorithm with diversity preservation (EDA-DP) is proposed. A chaotic mutation operator is introduced into EDA by taking advantage of the randomness, ergodicity, initial value sensitivity and regularity of chaos. The EDA-DP is able to adjust its mutation radius in an adaptive way according to the fitness value and the distance between each individual. Moreover, the EDA-DP is able to generate its offspring population by making use of the concentration inside the population. The EDA-DP is evaluated on a set of benchmark problems and the experimental results show that the precision of the optimal solutions and the convergence speed are improved, thanks to the EDA-DP effectively overcomes the premature convergence problem.
关键词：estimation of distribution algorithm;diversity;premature convergence;chaotic mutation2|1643|8更新时间：2025-07-16 - 摘要：Current mainstream on-chip bus protocol — AHB has a problem that the bandwidth utilization of memory accesses is quite low. This paper proposes a new optimization design based on the feature that there are massive DMA transfers in SoC. Proposed method adds MCS-DMA modules inside the memory controller and bind MCS-DMA modules to target DMA transfers via software drivers. On the one hand, it prefetches data to increase the bandwidth utilization of single DMA transfer; on the other hand, it makes memory requests pipelined inside the memory controller, which increases the bandwidth utilization of multiple parallel DMA transfers. After applying the design to PKUnity-SK SoC, the bus bandwidth utilization when transferring single DMA increases to 100%. When transferring multiple DMAs in parallel, the bus bandwidth utilization increases from 33.3% to 85.5%. However, the chip area only increases by 2.9%.
关键词：system-on-chip;memory controller;direct memory access (DMA)2|1848|3更新时间：2025-07-16 - 摘要：
Abstract: A novel skin color detection method in JPEG compressed domain has been proposed. Color and texture features of the image blocks are extracted from the entropy decoded DCT coefficients firstly. Then, data mining method is applied to set up the skin color model to describe the relationship between the image block features and the skin detection results, and the initial skin image blocks are detected based on the model. The skin color regions are finally segmented using region growing method. Experimental results show that, compared with the SPM (Skin Probability Map) skin color detection algorithm in pixel domain, the proposed method can achieve higher detection accuracy and faster detection speed.
关键词：skin color detection;compressed domain;data mining;region growing2|1281|2更新时间：2025-07-16 - 摘要：Bistatic Surface-Wave Over-the-Horizon Radar (SWOTHR) uses a coast-located array to transmit signals and a ship-carried omnidirectional antenna to receive echoes. In the transmit array, different element utilizes different carrier frequency. The analysis of the direct-path-interference leads to the conclusion that the direct wave is a kind of interference at a position and with a Doppler frequency. Based on the conclusion the interference suppression in time, range-angle and Doppler domain respectively is presented. These three methods for direct wave suppression are evaluated from the aspects of computation complexity, processing gain and output SINR. Finally the simulation and real data results are given to prove the effectivity of these methods.
关键词：coast-ship bistatic radar;surface-wave over-the-horizon radar;direct-path-interference suppression2|1434|2更新时间：2025-07-16 - 摘要：The electron scattering process of electron beam lithography in the thick resist was simulated by the Monte Carlo method with the optimized electron scattering model, the energy deposition density at the different depths of thick resist was calculated by using of the stratified method, and the three dimensional energy deposition model of the thick resist in the electron beam lithography was established. According to the three dimensional energy deposition mode, we have simulated the exposure of a three dimensional micro-structure of trapezoidal pyramid by the overlapped increment scanning strategy. Theoretical analysis and the simulation results show that the three dimensional energy deposition model based on the stratified method can realize the three dimensional simulation of the electron beam lithography more accurately.
关键词：electron beam lithography;proximity effect;exposure intensity;three dimensional energy deposition model2|1856|2更新时间：2025-07-16 - 摘要：HF band is a severe electromagnetic environment in which HF backscatter system works. All kinds of interference in this band having a strong impact on the system’s performance must be suppressed. Through analyzing the interference of the measured data of HF backscatter system, we find that some interference appears strong correlativity between adjacent range units.and between adjacent Doppler units, respectively. Aiming at this kind of interference, an interference suppressing method which is based on eigen subspace in Doppler field is proposed. The method is: firstly, interference convariance matrix is constructed in Doppler field, after eigenvalue decomposition of this matrix, the interference subspace is obtained, then the pending units are projected to the orthogonal supplement of the interference subspace, finaly, the interference is excised. The results of applying this method to the measured data show the effectivity of the proposed method.
关键词：HF backscatter system;transient interference;impulse interference;short interference;interference suppressing2|961|2更新时间：2025-07-16 - 摘要：Recently, it becomes difficult for normal radar system to detect the stealth targets and space objects, so the researchers have paid more attention to the MIMO radar. For moving targets, the probability density function of sufficient statistic is analyzed firstly; then, the meaning of four working mode is discussed; finally, based on four working mode, the MIMO radar system’s detection method and performance are development. By theoretical analysis and simulation, we get the conclusions witch are: MISO working mode is suitable for MIMO radar system, and the number of receive station should be 4~6.
关键词：MIMO radar;signal detection;diversity gain;sufficient statistic2|1854|9更新时间：2025-07-16 - 摘要：This paper proposes an orthogonal frequency division multiple access-based resource allocation algorithm for downlink cognitive radio systems, which targets to maximize the data transmission rate under the constraints of total transmit power, bit error rate and interference to the primary users. It includes two steps: firstly, the subcarriers are allocated according to the signal to interference plus noise ratio of each user over each subcarrier; secondly, the optimal bit and power solution is derived in the nonnegative real field and then adjusted into the bit and power allocation results suitable for the practical systems. Simulation results show that the proposed algorithm can provide significant data transmission rate gain comparing with the conventional resource allocation algorithms based on spectrum hole.
关键词：cognitive radio;resource allocation;orthogonal frequency division multiple access2|1257|11更新时间：2025-07-16 - 摘要：Because fuzzy sets exist deficiency on semantic description, much of the current research interest in neuro-fuzzy hybrid systems is focused on how to extend fuzzy neural networks. To deal with this problem, a self-organizing intuitionistic fuzzy networks based on UKF is presented. Firstly, structure of intuitionistic fuzzy networks and meanings of each layer is proposed. Secondly, training algorithm is deduced, and LLS and UKF are used to learn linear and non-linear parameters respectively. Thirdly, guideline of how to generate a new rule is given, and method of error descending rate is used as fuzzy rule pruning strategy, so that rule which plays an unimportant role in the system is deleted. At last, typical experiments of function approximation, system identification and prediction of time-series indicate that a fuzzy network obtained by the proposed algorithm has a more tighten structure and better generalization than other algorithms.
关键词：intuitionistic fuzzy sets;unscented Kalman filter;self-organising fuzzy neural networks (SOFNN);system identification;function approximation;time-series prediction2|1569|9更新时间：2025-07-16 - 摘要：Voice morphing is a technique to modify a source speaker’s speech to sound as if it was spoken by some designated target speaker. The Gaussian mixture model (GMM) based transformations combined with full-band extracted feature parameters have been commonly studied. However, these methods often introduce problems such as artifacts and discontinuities. In order to resolve the problem mentioned above, state-space model (SSM) is first used to describe the relationship between the source speech and the target speech in the spectral domain. Then Discrete Wavelet Transform (DWT) is applied to decompose speech signals into sub-bands in order to improve the quality of the converted speech. Finally, experiments using both objective and subjective measurements are conducted to validate the effectiveness of the proposed method.
.
关键词：voice morphing;Gaussian mixture model;state-space model;full-band conversion;sub-band conversion3|1344|5更新时间：2025-07-16 - 摘要：Integrated Electronic Information System standard applicability decides the accuracy of the system implementation. Combining the standard applicability requirements and characteristics together, the fuzzy AHP method and basic steps in analyzing standard applicability is introduced. Then a study case of standards applicability analysis in Integrated Electronic Information System is discussed and the validity of the method is confirmed. At last, thoughts and suggestions about comprehensive evaluation are given combining work experience.
关键词：fuzzy AHP;measures of merit;information systems;standard applicability.4|1699|3更新时间：2025-07-16 - 摘要：Multiple descriptions coding (MDC) has emerged as an attractive framework for robust transmission over unreliable channels and it has recently attracted the interest of many researchers. In order to solve that the parameters of fractal image coding are not suitable to be transmitted over the unreliable channels, the multiple description coding scheme based on fractal image coding (MDFIC) was proposed. The paper improves MDFIC on two aspects, i.e. using the fast fractal image coding algorithm based on FGSE to speed up the coding procedure and the corrections between the means of the closed range blocks to reduce the bit rate. Simulation results show that compared with the traditional scheme, with nearly the same quality of the decoded image, the proposed scheme has higher robustness and can efficiently speed up the encoding process and decrease the bit rate.
关键词：fractal image coding;multiple description coding;fine granularity successive elimination (FGSE)2|1028|0更新时间：2025-07-16 - 摘要：
A particle swarm optimization algorithm with fully communicated information is proposed. To begin with, an information-shared matrix, which provides a platform of information exchange among particles, is built. Then, normal distribution as a tool is used to synthesize information from the information-shared matrix. A method is used to modify particle position aiming to improve the information-shared level. Lastly, by using the method of position disturbance, the ability of utilizing information is enhanced. The obtained results on the benchmark functions show the effectiveness of the proposed algorithm.
关键词：pheromone-shared mechanism;particle swarm optimization;normal distribution;fully communicated information4|1268|8更新时间：2025-07-16 - 摘要：A novel double loop dual-mode bandpass filter is proposed which is composed of a quadrate resonator and a small quadrate loop for the purpose of perturbation. The small quadrate loop has two tunable parameters which increase the degree of freedom of dual modes and make the miniaturization easier. Tapped coupling can be used to change the transmission zeros so that the performance of filter is improved. A prototype filter is designed and fabricated with a measured center frequency of 2.41GHz, 17.77% fractional bandwidth, a low passband insertion loss of 0.67dB ,a high passband return loss of 17dB and a wide stop band with rejection better than 20dB.
关键词：bandpass filter;dual mode;double loop2|1757|2更新时间：2025-07-16 - 摘要：A robust detection method for inverse synthetic aperture radar (ISAR) target using high resolution range profiles (HRRP) is proposed. The proposed detector ,improved robust generalized likelihood rate test (IRGLRT), is derived by estimating signal from every range cell through an improved second order cone programming (SOCP). Furthermore, lower computational complexity is analyzed, constant false alarm rate (CFAR) property is proved and the detection threshold is estimated. Finally, experimental results for measured data of three planes illustrate that IRGLRT achieves a visible performance improvement comparing with conventional generalized likelihood rate test (GLRT), especially in the presence of severe steering vector mismatches.
关键词：inverse synthetic radar target detection;high resolution range profiles (HRRP);second order cone programming (SOCP);constant false alarm rate (CFAR)3|1233|2更新时间：2025-07-16 - 摘要：There is no alias-free FOV when the least space is more than 3.07 wavelengh because of bigger receiver size in 8mm aperture synthesis microwave radiometers. Background cancellation method which can eliminate aliasing in removable object's imaging is no useful when the scene cannot move. This paper give a new starlike array whose visibility samples is half of receiver size, so there is no severity aliasing problem in the new starlike array . The result of the emulate experiment show the imaging quality of starlike array is more higher than the quality of Y array.
关键词：aperture synthesis microwave radiometers;array;visibility samples;starlike array;Y array;baseline2|1196|0更新时间：2025-07-16 - 摘要：
It is known that detecting a high-speed and accelerating target is affected by the range migration and Doppler frequency migration in the linear frequency modulation pulse compression radar. In order to solve this problem, the model of received signal is established and the characteristics of the received signal are analyzed firstly. Then a target detection algorithm based on the scaling processing and the fractional Fourier transform is proposed. With the proposed algorithm, the range migration is compensated via using the scaling processing, and the Doppler frequency migration is compensated by using the fractional Fourier transform. Therefore it is able to improve the detection performance of a high-speed and accelerating target.
关键词：range migration;Doppler frequency migration;scaling processing;fractional Fourier transform2|1468|14更新时间：2025-07-16 - 摘要：Microwave-induced thermo-acoustic (MITA) Tomography is a promising technique in medical imaging area. It is a combination of the microwave and ultrasound techniques. In this paper, an experimental system of MITA is briefly presented. The mechanism of MITA and some signal processing methods are applied in analyzing the characteristics and affects of the MITA signals. The affects, the irradiated microwave pulse and the geometry of the tissue are studied. Experiment results and theoretic analysis show that the amplitude of the time domain MITA signals are proportional to the intensity of the irradiated microwave pulse and the cross-section of the sample. The spectrum distribution of the MITA signals are not only affected by the spectrum of the irradiated microwave, but also affected by the intrinsic frequency determined by the tissue’s thickness. The center frequency of the MITA signals recorded in experiment accord with this hypothesis.
关键词：microwave-induced thermo-acoustic (MITA);characteristics of signals;temporal and frequency analysis2|1663|0更新时间：2025-07-16 - 摘要：A new type quasi-continuous radar which take a double linearly frequency interrupted modulation signal with large operating duty as the transmitting wave is proposed in order to solve the range-velocity coupling problem in the LFM-CW radar and the short-range blind area problem in LFM pulse radar. In this quasi-continuous radar, two LFM signals whose spectrums are not overlapped are transmitted alternately in the transmitting pulse, and the estimated values of the range and the velocity can be obtained within a pulse repetition interval in the receiver by the separating the transmitted signals, Stretch processing, correlation processing, FFT and the motion compensating. In this paper, the signal model and the principle of range-velocity decoupling are firstly given. And then its performance is analyzed. Finally, some key problems to be solved are discussed in the radar.
关键词：quasi-continuous radar;Stretch processing;range-velocity decoupling;short-range blind area2|1542|2更新时间：2025-07-16 - 摘要：In recent years, outlier detection has gained considerable interest. The identification of outliers is important for many applications such as intrusion detection, credit card fraud, criminal activities in electronic commerce, medical diagnosis and anti-terrorism, etc. The aim of outlier detection is to find small groups of objects who behave in an unexpected way or have abnormal properties when compared with the rest large amount of data. Since the existing methods for outlier detection cannot deal with uncertain and incomplete data. In this paper, we propose a new method for outlier definition and detection, which exploits the basic notion — boundary of rough sets and Knorr’s method about distance-based outliers. We also give an algorithm BDOD to find such outliers within the framework of rough set theory. The effectiveness of our algorithm is demonstrated on publicly clinical diagnosis data sets. Our method gives a new approach to the solution of uncertain and incomplete data in outlier detection.
关键词：data mining;outlier detection;rough sets;uncertain and incomplete data2|2130|18更新时间：2025-07-16 - 摘要：WKB method is often used to calculate the electromagnetic wave propagation in the inhomogeneous plasma, but the coupling effect between the forward wave and backward wave is neglected in the propagation process of the electromagnetic wave in the medium. Making use of the differential transfer matrix methodology, the solution of modified WKB can be improved to the second order approximation and be more accurate than that of WKB for taking into account the coupling effect. Based on this modified WKB method, the waveform of an electromagnetic pulse through an inhomogeneous plasma region is analyzed. The fast Fourier transform algorithm is used to obtain the distortion of the transmission signal waveforms such as the Gaussian pulse signal through a symmetrical plasma distribution and the results show that the amplitude of signal becomes lower under the consideration of coupling effect and so the modified WKB method is suited to analyze the waveform of the transmitted pulse.
关键词：plasma;WKB;inhomogeneous2|1128|0更新时间：2025-07-16 - 摘要：Transient dynamics is a key issue for optically pumped quantum well THz laser, which is analyzed for the first time in this paper based on an ensemble Monte Carlo simulation (EMC). The prototype designed is a 3-level stepped modulation doped GaAs/GaxAl(1-x)As quantum well. In this EMC there are electron-electron (e-e), electron-optical phonon and electron-acoustic phonon scatterings included, and the electron-ionized impurity scattering can be ignored due to modulation doping. The reported THz prototypes of 3-level stepped quantum well were all based on doping in the deepest quantum well, and inconsistent conclusions were drown about the population inversion. We find that population inversion is found in our designed device prototype with temperature 77K and at certain pumping flux.
关键词：THz laser;modulation doping;asymmetrical stepped quantum well;Monte Carlo method2|1073|0更新时间：2025-07-16 - 摘要：Statistics characteristics of polarimetric scattering from chaff cloud is studied. At first, the more accurate calculation result is given, which tells how the current value varied with the direction of incident electromagnetic. On this basis, polarimetric scattering matrix and RCS matrix of chaff are presented, and their statistics chafteristics are studied. Then PDF function of chaff cloud’s altitude、RCS and polarimetric scattering vector are derived. A series of conclusions are draw at last, such as: the correlation coefficient between the two co-polarized channels is 1/3, the correlation between the co-polarized and cross-polarized channels is zero.
关键词：dipole;chaff cloud;polarization;scattering;statistics characteristics2|1786|9更新时间：2025-07-16 - 摘要：
A strong blind quantum signature protocol was presented based on secret sharing. In this protocol, the three photons of each GHZ (Greenberger-Horne-Zeilinger) triplet are delivered to the message owner Alice, signatory Trent and verifier Bob respectively. Alice measures her photon to blind her message while Trent measures his photon to sign the blinded message, and then Bob verifies the signature according to the measuring results of his photon under the relationship of GHZ states. However, Bob’s actions are restricted by the quantum fingerprints and the audit program. Our protocol ensures that the signature is blind and the message owner is untraceable. Moreover, its security was not influenced by the computational resource of attackers.
关键词：strong blind signature;secret sharing;quantum cryptography2|1488|16更新时间：2025-07-16 - 摘要：A new kind of broadband output circuit of rectangular π-TM310 mode double-gap cavity loaded by coaxial line filter is propounded and its feasibility is demonstrated. Some attention-getting cruxes, such as the influence of adjacent modes on the gap impedances and the power capacity of the coaxial line output circuit, are discussed. Smaller length-width ratio and a concave structure of rectangular cavity are adopted to magnify the frequency interval between the π-TM310 mode and adjacent modes. Then the disturbance from non-working modes can be effectively suppressed. The beam holes are disposed on novel but suitable positions so that the characteristic impedances along different beam holes are more uniform, and remain uniform after the rectangular π-TM310 mode double-gap cavity is loaded by a coaxial line filter. Our research results show that the optimum designed output circuit of rectangular π-TM310 mode double-gap cavity loaded by coaxial line filter has a very wide band. The relative bandwidth in X band reaches 14% or so. But the output power capacity is relatively low, about a few hundreds of kW, because the cavity’s coupling hole with the coaxial line is relatively small, furthermore, in which there is a metal pin. So the output circuit is fit for medium power broadband multi-beam klystrons of X band or higher frequency.
关键词：multi-beam klystron;high order mode;double-gap cavity;broadband output circuit;coaxial line filter2|1287|3更新时间：2025-07-16 - 摘要：The capabilities of neural networks are influenced by the learning algorithms and the topologies. Thus, in order to solve the problem of dynamic topologies, a new design method for dynamic structure of neural network is proposed in this paper. The dynamic design for neural network is based on the sensitivity analysis (SA) of the model output. This algorithm can delete the nodes in the hidden layer whose contribution ratios are too little; and add new nodes to the hidden layer whose ratios are too large relied on the the nearest neighbor interpolation. Finally, This proposed algorithm is used to track the nonlinear functions and predict the nonlinear systems, the results demonstrate the good effect of the dynamic feed-forward neural network (SAFNN).
关键词：neural network;design of dynamic structure;sensitivity analysis of model output2|1432|7更新时间：2025-07-16
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0