检索结果-南通市图书馆

Design and performance analysis of orthogonal coding signal in MIMO-SAR

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Information sciences) 2011年第8期54卷 1723-1737页

作者： ZOU Bo,DONG Zhen & LIANG DianNong school of Electronic science and technology,national University of defense technology,Changsha 410073,china 1. school of Electronic science and technology National University of Defense Technology Changsha 410073 China

Multi-input multi-output (MIMO) radar which has evident advantages in many applications is a new radar *** the MIMO technique to the earth observing synthetic aperture radar (SAR) system offers effective ways for the improvement of high resolution and wide swath imaging and ground moving target indication (GMTI) *** the optimal orthogonal waveform is a crucial problem in the research on MIMO ***,the index definition of synthetic integrated side-lobe level ratio (ISLR) is proposed by focusing on the SAR application and considering the cross-correlation energy influences between orthogonal coding signals with the same frequency ***,it is theoretically demonstrated that the performance of synthetic ISLR of orthogonal coding signals with the same frequency band cannot meet the demands of SAR imaging,which has been proved by one-dimensional numerical simulation. Third,it has been shown through numerical simulation that the performance of synthetic ISLR of orthogonal coding signals still cannot be improved by dealing with the mismatched ***,a set of orthogonal phase coding signals are designed for multiple MIMO-SAR *** conclusions are verified through MIMO-SAR imaging and InSAR simulation experiments.

关键词： MIMO-SAR waveform design orthogonal coding signal synthetic ISLR

A type of M2 -transmitter N2 -receiver MIMO radar array and 3D imaging theory

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Information sciences) 2011年第10期54卷 2147-2157页

作者： ZHU YuTao & SU Yi school of Electronic science and Engineering,national University of defense technology,Changsha 410073,china 1. school of Electronic science and Engineering National University of Defense Technology Changsha 410073 China

With two-dimensional synthetic apertures,a wideband radar array can realize 3D imaging of air targets,but this needs large numbers of antenna ***,when the transmitting frequency is very high,the interval of array elements makes it hard to fit the available space,which makes the imaging resolution *** paper proposes a type of M 2 -transmitter N 2 -receiver multiple-input multiple-output (MIMO) radar,which is equivalent to a rectangular radar array with (M N) 2 T/R antenna elements based on phase center approximation theory,and which can realize the 3D imaging of air *** 3D imaging theory and MIMO inverse synthetic aperture radar (MIMO-ISAR) 3D imaging theory are also proposed in this paper,and two simulations are given to show their validity.

关键词： MIMO radar array phase center approximation 3D imaging ISAR

Focusing transform-based direction-of-arrival method exploiting multi-cycle frequencies

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2005年第6期15卷 491-495页

作者： HUANG Zhitao*, JIANG Wenli and ZHOU Yiyu(school of Electronic science and Engineering, national University of defense technology, Changsha 410073, china) school of Electronic science and Engineering National University of Defense Technology Changsha 410073 China

When single cycle frequency is employed, the existing spectral correlation-signal subspace fitting (SC-SSF) algorithms usually contain two disadvantages: those single-cycle estimators cannot reach the best performance; it is inconvenient to be applied in practice since the right cycle frequency has to be selected. Based on the Jacobi-Anger expansion and the idea of focusing transform, a new approach exploiting multi-cycle frequencies of cyclostationary signal is discussed in this paper. Simulation results demonstrate the effectiveness of the new method.

关键词： cyclostationary signal direction-of-arrival multi-cycle frequencies focusing transform.

Sidelobe reduction based on spectrum reshaping in microwave imaging

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Information sciences) 2011年第1期54卷 204-212页

作者： WANG HuaiJun,SU Yi,XU HongBo & ZHU YuTao school of Electronic science and Engineering,national University of defense technology, Changsha 410073,china 1. school of Electronic science and Engineering National University of Defense Technology Changsha 410073 China

Sidelobe artifacts are a common problem in image reconstruction from finite-extent Fourier data obtained by microwave imaging *** order to enhance the image quality,sidelobe reduction must be *** the sidelobe reduction in microwave imaging as the research subject,this paper presents Fourier imaging technique *** the point spread function is obtained through Fourier inversion of rectangular spectral support data and the changing effect of sidelobe direction due to reshaping spectral support is *** reshaping makes that the sidelobes of two Fourier images do not *** on the idea of separating sidelobes from mainlobe,a nolve method that reduces sidelobe levels while maintaining the imaging resolution is *** performance of this method is ***,the simulated and measured data of typical microwave imaging systems such as synthetic aperture radar(SAR),inverse synthetic aperture radar(ISAR)and real aperture radar are used to demonstrate the validity of the proposed method.

关键词： microwave imaging Fourier imaging sidelobe reduction spatial spectrum point spread function

Parallel Algorithm in Surface Wave Waveform Inversion

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural sciences 2001年第Z1期6卷 574-578页

作者： Cao Xiao lin, Song Jun qiang school of Computer science, national University of defense technology, Changsha 410073, china school of Computer science National University of Defense Technology Changsha China

In Surface wave waveform inversion, we want to reconstruct 3D shear wave velocity structure, which calculation beyond the capability of the powerful present day personal computer or even workstation. So we designed a high paralleled algorithm and carried out the inversion on Parallel computer based on the partitioned waveform inversion (PWI). It partitions the large scale optimization problem into a number of independent small scale problems and reduces the computational effort by several orders of magnitude. We adopted surface waveform inversion with a equal block(2 o×2 o) discretization.

关键词： surface wave waveform inversion parallel algorithm partitioned waveform inversion

Trajectory Estimation with Multi-range-rate System Based on Sparse Representation and Spline Model Optimization

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2010年第1期23卷 84-90页

作者： Liu Jiying,Zhu Jubo,Xie Meihua Department of Mathematics and Systems science,national University of defense technology,Changsha 410073,china [a] Department of Mathematics Systems science National University of Defense Technology Changsha 410073 China

The classic state methods for trajectory estimation in boost phase with multi-range-rate system include method of point-by-point manner and that of spline-model-based manner. Both are deficient in terms of model-approximation accuracy and systematic error determination thus resulting in the estimation errors well beyond the requirements, especially, concerning the maneuvering trajectory. This article proposes a new high-precision estimation approach based on the residual error analysis. The residual error comprises three components, i. e. systematic error, model truncation error and random error. The approach realizes self-adaptive estimation of systematic errors in measurements following the theory of sparse representation of signals to minimize the low-frequency components of residual errors. By taking median- and high-frequency components as indexes, the spline model-approximation is improved by optimizing node sequence of the spline function and the weight selection for data fusion through iteration. Simulation has validated the performances of the proposed method.

关键词： tracking radar systematic errors truncation error sparse representation splines

Data fusion techniques for incomplete measurement of trajectory

在线全文

学校读者我要写书评

暂无评论

Chinese science Bulletin 2001年第8期46卷 627-630页

作者： ZHU JuboDepartment of Mathematics & System science, national University of defense technology, Changsha 410073, china Department of Mathematics & System science National University of Defense Technology Changsha China

This paper focuses on data processing for incomplete measurement of trajectory (IMT) in aerospace measurement and control. The IMT means that the principal equipment loses the measured data during some intervals so that trajectory parameters (position, velocity, etc.) cannot be determined independently. Based on a joint model for trajectory estimation with reduced parameter, a fusion way is put forth by making full use of measured data from auxiliary equipment with lower precision. In the superposition intervals of measurement between principal and auxiliary equipment, the technique of diagnosing and estimating system errors is applied to improving the estimate precision of trajectory parameters (TP) and determining the precision after data fusion. In practical test, this method operates so successfully that it can not only provide complete TP but improve their precision remarkably. Meanwhile, this way is also applicable to other problems of incomplete measurement.

关键词： incomplete measurement of trajectory data fusion re- duced parameter model error diagnose.

Jamming de-chirping radar using interrupted-sampling repeater

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2011年第10期54卷 2138-2146页

作者： FENG DeJun ,TAO HuaMin,YANG Yong & LIU Zhong school of Electronic science and Engineering,national University of defense technology,Changsha 410073,china 1. school of Electronic science and Engineering National University of Defense Technology Changsha 410073 China

Interrupted-sampling repeater jamming (ISRJ) is a novel jamming mode for pulse compression radar in *** this paper,a jamming approach of applying ISRJ to de-chirping radar is *** principles of ISRJ are expounded,and the ways to achieve a train false target for de-chirping radar are *** characteristics of false target,including time-domain characteristic,frequency-domain characteristic and amplitude characteristic,are *** on this,the power requirement for jammer is put forward and the key elements that determine the space distribution location between true and false targets are discussed in *** last,simulation results are presented and *** work is beneficial to the jamming design and use of ISRJ.

关键词： interrupted-sampling repeater de-chirping wideband radar linear frequency modulated signal

Prediction of Enthalpies of Fusion for Divalent Rare Earth Halides Based on Modeling by Artificial Neural Networks and Pattern Recognition

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 24-26页

作者： Yimin Sun Zhiyu Qiao Minghong He(Applied science school, University of science & technology Beijing, Beijing 100083, china)(national Natural science Foundation of china, Beijing 100083, china) Applied science school University of Science and Technology Beijing Beijing 100083 China national Natural science Foundation of china Beijing 100083 China

The artificial neural network (ANN) and the pattern recognition were applied to study the correlation of enthalpies of fusion for divalent rare earth halides with their microstructural parameters,such as ionic radius and electronegativity. The model,represented by a back-propagation netal network, was trained with a 12 set of published data for divalent rare earth halides and then was used to predict the unknown ones. Also the criterion equations were ptesented to determine the enthalpies of fuSion for divalent rare earth halides using pattern recognition in mis work. The results from the model in ANN and criterion equations are in very good agreement with reference data.

关键词： BP neural network pattern recognition enthalpy of fusion divalent rare earth halides microstructural parameters