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SPECTRAL-DIFFERENCE METHOD FOR TWO-DIMENSIONAL COMPRESSIBLE FLUID FLOW

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Journal of Computational Mathematics 1998年第1期16卷 15-26页

作者： Yue-shan Xiong (Department of computer, national university of defense technology, changsha, china) 国防科技大学计算机系湖南长沙

We develop a combined Fourier spectral-finite difference method for solving 2-dimensional, semi-periodic compressible fluid how problem. The error estimation, as well as the convergence rate, is presented.

关键词： spectral-difference method compressible fluid flow error estimation

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A new satellite to satellite tracking algorithm from Doppler-shifted frequency measurements

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Progress in Natural Science:Materials International 2007年第10期17卷 1226-1234页

作者： Li Qiang, Guo Fucheng and Zhou Yiyu(school of Electronic Science & Engineering, national university of defense technology, changsha 410073, china) school of Electronic Science & Engineering National University of Defense Technology Changsha 410073 China

A new satellite to satellite tracking (SST) algorithm from Doppler-shifted frequency measurements is proposed. The estimation principle is demonstrated and the mathematic model of SST is established. The state estimation methods for a user (the cooperative case) and target satellites (the non-cooperative case) are presented based on particle swarm optimization (PSO). The Cramer-Rao lower bounds (CRLB) are deduced as well. Performance of the new algorithm is validated through computer simulations, which proved that the proposed method is effective in terms of the estimation quality compared with CRLB and superior in accuracy to the Bearings-Only (BO) method in almost all simulation cases except for the case that an enough long tracking arc-length is obtained for a user satellite.

关键词： satellite to satellite tracking (SST) Doppler-shifted frequency (DSF) Space Surveillance Network (SSN) particle swarm optimization (PSO).

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

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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

Narrowband imaging method for spatial precession cone-shaped targets

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Science china(Technological Sciences) 2010年第4期53卷 942-949页

作者： DING XiaoFeng1,FAN MeiMei1,WEI XiZhang1,LI Xiang1 & Xiao HuaiTie2 1 Institute of Space Electronics Information technology,national university of defense technology,changsha 410073,china 2 school of Electronic Science and Engineering,national university of defense technology,changsha 410073,china 1. Institute of Space Electronics Information technology National University of Defense Technology Changsha 410073 China2. School of Electronic Science and Engineering National University of Defense Technology Changsha 410073 China

The imaging method of the mid-course missile is the key technique of the missile defense *** of the special precession character of the ballistic missile warhead,the inverse synthetic aperture radar method cannot realize phase compensation with the constant phase offset function,which leads to blurring of the *** this paper,we propose a new narrowband radar imaging method for the precession cone-shaped *** method acquires the Doppler modulation of the precession target's scattering centers with high resolution time-frequency analysis method and extracts the Doppler parameter from the result of the time-frequency analysis with the general Radon transform,then reconstructs the scattering centers positions in the parameter *** experiment results with the anechoic chamber data of the representative cone-shaped object showed the effectiveness of the method.

关键词： narrowband radar imaging time-frequency analysis general Radon transform

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

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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

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

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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.

Device-physics-based analytical model for SET pulse in sub-100 nm bulk CMOS Process

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Science china(Information Sciences) 2012年第6期55卷 1461-1468页

作者： QIN JunRui,CHEN ShuMing,LIU BiWei,LIANG Bin & CHEN JianJun school of computer Science,national university of defense technology,changsha 410073,china 1. school of computer Science National University of Defense Technology Changsha 410073 China

Through revising the process of charge collection for reversed drain-bulk junction,a bias-dependent SPICE model is proposed which includes the bipolar amplification effect that cannot be ignored in *** model can capture the plateau effect,and produce current and voltage pulse shapes and widths that are consistent with TCAD *** the case of connecting load,it is still *** combination and sequential logic circuits,the SET pulsewidths and LET upset threshold from SPICE model are consistent with TCAD simulations.

关键词： SET SEU SPICE modeling parasitic bipolar transistor

SCautz:a high performance and fault-tolerant datacenter network for modular datacenters

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Science china(Information Sciences) 2012年第7期55卷 1493-1508页

作者： HUANG Feng,LU XiCheng,LI DongSheng & ZHANG YiMing national Lab for Parallel and Distributed Processing,school of computer,national university of defense technology,changsha 410073,china 1. national Lab for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha 410073 China

Modular datacenters (MDCs) use shipping containers,encapsulating thousands of servers,as large pluggable building blocks for mega *** MDC’s "service-free" model poses stricter demand on fault-tolerance of the modular datacenter network (MDCN).Based on the "scale-out" principle,in this paper we propose SCautz,a novel hybrid intra-container network for *** comprises a base Kautz topology,created by interconnecting servers,and a small number of COTS (commercial off-the-shelf) ***,each switch connects a specific number of servers forming "clusters",which,as logical nodes,form multiple higher-level logical Kautz ***’s hybrid structure has several ***,it supports multiple running modes for the MDC,while its full structure increases network capacity ***,it retains the throughput for processing one-to-x traffic in the presence of ***,it achieves much more graceful network performance degradation than computation and storage capacity *** from theoretical analysis and simulations show that SCautz is more viable for intra-container networks.

关键词： modular datacenter network container Kautz fault-tolerant

Review on abort trajectory for manned lunar landing mission

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Science china(Technological Sciences) 2010年第10期53卷 2691-2698页

作者： XI XiaoNing1, HUANG WenDe2 & WANG Wei2,3 1 College of Mechatronics Engineering and Automation, national university of defense technology, changsha 410073, china 2 College of Aerospace and Material Engineering, national university of defense technology, changsha 410073, china 3 school of Surveying and Spatial Information System, university of New South Wales, Sydney, NSW 2052, Australia 1. College of Mechatronics Engineering and Automation National University of Defense Technology Changsha 410073 China2. College of Aerospace and Material Engineering National University of Defense Technology Changsha 410073 China3. School of Surveying and Spatial Information System University of New South Wales Sydney NSW 2052 Australia

Abort trajectory is a passage that ensures the astronauts to return safely to the earth when an emergency occurs. Firstly,the essential elements of mission abort are analyzed entirely based on summarizing the existing studies. Then,abort trajectory requirement and rational selection for different flight phases of typical manned lunar mission are discussed specifically. Considering a trade-off between the two primary constrains of an abort,the return time of flight and energy requirement,a general optimizing method for mission abort is proposed. Finally,some suggestions are given for china’s future manned lunar landing mission.

关键词： manned lunar landing mission abort trajectory design free return trajectory

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