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Relaying Selection with Network-coded Cooperative Protocols in Aeronautical Communications

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Chinese Journal of Aeronautics 2010年第1期23卷 75-83页

作者： Du Bing,Zhang Jun School of electronics and information engineering,beijing university of Aeronautics and Astronautics,beijing 100191,china School of electronics and information engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China

In this article, we exploit the idea of network-coded cooperative protocol in aeronautical communications which combines different source nodes＇ information at the relay and joint decoding at the destination. Recently, the network coding in cooperative communications has been categorized into two mainstreams, bit-level and signal-level combinations, which are both discussed in the article. And to be exclusively,multiple access relay channel（MARC） is adopted. The mutual information expressions of both above-cited network-coded protocols are deduced, which prove that without proper selected relays to perform network coding, the spatial diversity of the proposed protocol cannot be obtained. This then leads to search for the selection and grouping algorithms. An adjacency matrix is defined to describe the connectivity of the nodes in one radio contact disk, so that, the selection and grouping of algorithm is equivalent to constructing this adjacency matrix to minimize the system outage probability evaluated in term of the mutual information. Besides, a network-coded cooperative protocol requires the acyclic network, of which the construction is to avoid loop-4 in the matrix. The article ends with simulations to demonstrate the viability of the proposed algorithms.

关键词： communication network coding outage probability mutual information bit-level signal-level

Compressive sensing SAR range compression with chirp scaling principle

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Science china(information Sciences) 2012年第10期55卷 2292-2300页

作者： XIAO Peng,YU Ze & LI ChunSheng School of electronics and information engineering,beihang university,beijing 100191,china School of electronics and information engineering Beihang University Beijing China

Compressive sensing(CS) techniques offer a framework for the detection and allocation of sparse signal with a reduced number of *** paper proposes a novel SAR range compression,namely compressive sensing with chirp scaling(CS-CS),achieving the same range resolution as conventional SAR approach,while using fewer range *** order to realize accurate range cell migration correction(RCMC),chirp scaling principle is used to construct reference matrix for compressive sensing ***,error diagrams are designed for measurement of the performance of CS-CS,and some experiments of using real data are performed to deal with the errors caused by three conditions:SNR,sparsity and sampling.

关键词： synthetic aperture radar compressive sensing range cell migration correction error radar signal processing

Statistical approach to weak signal detection and estimation using Duffing chaotic oscillators

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Science china(information Sciences) 2011年第11期54卷 2324-2337页

作者： JIN Tian & ZHANG Hua School of Electronic information engineering,beihang university,beijing 100191,china School of Electronic information engineering BeiHang University Beijing China

In this paper,we describe the statistical characteristics of weak signal detection by a chaotic Duffing oscillator,and present a new method for signal detection and estimation using the largest Lyapunov *** research has shown that weak signals can be detected by a chaotic *** researchers use the Lyapunov exponent to flag the detection of a chaotic state,but our research shows that the Lyapunov exponent follows statistical characteristics,and therefore more factors should be considered in flagging chaotic weak ***,we analyze the statistical characteristics inherent in the Lyapunov exponent calculation steps,and build up a statistical model for different chaotic states based on simulation ***,we provide expressions for false-alarm and detection probabilities,selection of driving force threshold and detection of ***,we summarize the method of signal amplitude *** research indicates that the performance of the detection system is related to sampling times and intervals,in accord with the theory of statistical signal detection.

关键词： weak signal detection Lyapunov exponent chaos Duffing oscillation statistical signal process

A GTD model and state space approach based method for extracting the UWB scattering center of moving target

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Science china(information Sciences) 2011年第1期54卷 182-196页

作者： WANG Jun,WEI ShaoMing,SUN JinPing & MAO ShiYi School of Electronic and information engineering,beihang university,beijing 100191,china School of Electronic and information engineering Beihang University Beijing China

Movements of the scattering center on the condition of ultra-wideband(UWB)will impact the extraction of *** paper presents an approach for extracting the moving targets’UWB scattering center parameters based on the geometrical theory of diffraction(GTD)model and the state space approach. Firstly,the UWB GTD scattering model is transformed into state-space equations in order to estimate the range and range rate through the singular value ***,the type parameter in the whole bandwidth is indicated dimension-reducedly by orthonormalized basis and estimated by traversal algorithm and minimumnorm ***,the intensity of scattering center is worked out based on the least square *** paper provides the Cramer-Rao bound(CRB)for parameter *** effectiveness of the approach is verified by computer *** approach can estimate range,range rate,reflection intensity and type parameter simultaneously in order to improve the track of scattering centers and the target identification.

关键词： scattering center extraction GTD model state space approach ultra-wideband Doppler processing

Adaptive control for autonomous rendezvous of spacecraft on elliptical orbit

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Acta Mechanica Sinica 2009年第4期25卷 539-545页

作者： Shan Lu Shijie Xu School of Astronautics, beihang university,100191 beijing, china School of Astronautics Beihang University Beijing China

A strategy for spacecraft autonomous rendezvous on an elliptical orbit in situation of no orbit information is developed. Lawden equation is used to describe relative motion of two spacecraft. Then an adaptive gain factor is introduced, and an adaptive control law for auton- omous rendezvous on the elliptical orbit is designed using Lyapunov approach. The relative motion is proved to be ultimately bounded under this control law, and the final relative position error can achieve the expected magnitude. Simulation results indicate that the adaptive control law can realize autonomous rendezvous on the elliptical orbit with relative state information only.

关键词： Autonomous rendezvous Elliptical orbit Lyapunov approach Adaptive control Gain factor

A novel spaceborne SAR wide-swath imaging approach based on Poisson disk-like nonuniform sampling and compressive sensing

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Science china(information Sciences) 2012年第8期55卷 1876-1887页

作者： SUN JinPing,ZHANG YuXi,TIAN JiHua&WANG Jun School of Electronic and information engineering,beihang university,beijing 100191,china School of Electronic and information engineering Beihang University Beijing China

Since the range swath width in the conventional single channel spaceborne synthetic aperture radar(SAR)is restricted by the system parameters,there is a trade-off between the azimuth resolution and the swath width in order to satisfy the Nyquist sampling *** this paper,we propose a novel spaceborne SAR wide-swath imaging scheme based on compressive sensing(CS)for the sparse *** proposed method designs a Poisson disk-like nonuniform sampling pattern in the azimuth direction,which meets the demand of wider swath by restricting the smallest time interval between any two azimuth samples,with the conventional sampling pattern preserved in the range *** a similar way to the processing procedure of spectral analysis(SPECAN)algorithm,the linear range migration correction(RMC)is realized while carrying out range compression,which can meet the demand for focusing with middle level *** reduce the computation load of CS reconstruction,we propose a novel fast reconstruction algorithm based on nonuniform fast Fourier transform(NUFFT),which greatly reduces the computation complexity from O(2M N)to O(4N log N).Experiment results validate the effectiveness of the proposed methods via the point target simulation and the Radarsat-1 raw data processing in F2 mode.

关键词： SAR wide-swath imaging compressive sensing NUFFT

A Linear Domain System Identification for Small Unmanned Aerial Rotorcraft Based on Adaptive Genetic Algorithm

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Journal of Bionic engineering 2010年第2期7卷 142-149页

作者： Xusheng Lei,Yuhu Du School of the Instrumentation Science and Opto-Electronic engineering,beihang university,beijing 100191,P.R.china School of the Instrumentation Science and Opto-Electronic engineering Beihang University Beijing P. R. China

This paper proposes a new adaptive linear domain system identification method for small unmanned aerial *** the flash memory integrated into the micro guide navigation control module, system records the data sequences of flighttests as inputs (control signals for servos) and outputs (aircraft’s attitude and velocity information).After data preprocessing, thesystem constructs the horizontal and vertical dynamic model for the small unmanned aerial rotorcraft using adaptive *** identified model is verified by a series of simulations and *** between flight data and the one-stepprediction data obtained from the identification model shows that the dynamic model has a good estimation for real unmannedaerial rotorcraft *** on the proposed dynamic model, the small unmanned aerial rotorcraft can perform hovering,turning, and straight flight tasks in real flight tests.

关键词： small unmanned aerial rotorcraft dynamic space model model identification adaptive genetic algorithm

Matrix calculation of high-dimensional cross product and its application in automatic recognition of the endmembers of hyperspectral imagary

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Science china(information Sciences) 2011年第1期54卷 197-203页

作者： GENG XiuRui1,ZHAO YongChao1,LIU SuHong2 & WANG FuXiang3 1Key Laboratory of Technology in Geo-spatial information Processing and Application System, Institute of electronics,Chinese Academy of Sciences,beijing 100080,china 2State Key Laboratory of Remote Sensing Science,Jointly Sponsored by beijing Normal university and the Institute of Remote Sensing Applications of Chinese Academy of Sciences, School of Geography,beijing Normal university,beijing 100875,china 3School of electronics and information engineering,beihang university,beijing 100191,china Key Laboratory of Technology in Geo-spatial information Processing and Application System Institute of Electronics Chinese Academy of Sciences Beijing China State Key Laboratory of Remote Sensing Science Jointly Sponsored by beijing Normal university and the Institute of Remote Sensing Applications of Chinese Academy of Sciences School of Geography Beijing Normal University Beijing China School of electronics and information engineering Beihang University Beijing China

This paper gives the definition of the high-dimensional cross product and its calculation by extending the 3-D cross product definition into the high-dimensional vector *** on the properties of the cross product,the volume variance index(VVI)is proposed to be used in extracting automatically the endmembers of the hypherspectral imagery which eliminates the shortcoming of the traditional method of using simplex only where the extraction results were easily impacted by the abnormal pixels.A case study of endmembers extraction experiment using the VVI method with the AVIRIS data for Cuprite has shown a very good result.

关键词： endmember simplex hyperspectral imagery cross product

Large field of view computed laminography with the asymmetric rotational scanning geometry

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Science china(Technological Sciences) 2010年第8期53卷 2261-2271页

作者： FU Jian 1,2 ,JIANG BaiHong&LI Bin 1 School of Mechanical engineering and Automation,beihang university,beijing 100191,china 2 Research Center of Digital Radiation Imaging and Biomedical Imaging,beihang university,beijing 100191,china School of Mechanical engineering and Automation Beihang University Beijing China Research Center of Digital Radiation Imaging and Biomedical Imaging Beihang University Beijing China

X-ray computed laminography(CL)is used in the fields of industrial inspection and medical *** can provide the internal structure three-dimensional(3D)information of a region of the objects *** is important to the clinical diagnosis and the quality control of flat objects like printed circuit boards,aircraft wings and satellite solar *** the restriction that the imaging region must be within the X-ray beam formed by the X-ray source and the detector,the imaging field of view of CL is limited by the size of detector.A new CL method with an asymmetric rotational cone-beam scanning geometry,called large field of view CL,is presented to overcome the existing *** can extend the imaging region when the imaging spatial resolution keeps the same as that of the conventional *** can also improve the imaging spatial resolution when the imaging region keeps the same as that of the conventional *** asymmetric configuration can be achieved by offsetting the detector from the conventional symmetric *** does not,however,require new detectors and X-ray source nor alter the scanning mechanical *** filtered back-projection(FBP)reconstruction algorithm and the data truncation smoothing functions have been deduced to reconstruct the images directly from the data acquired with this asymmetric *** performed numerical studies and experiments to demonstrate and validate the proposed approach. Results in these studies and experiments confirm that the proposed method can enlarge the imaging region and improve the spatial *** proposed approach may find applications in the CL system with the rotational scanning geometry.

关键词： computed laminography image reconstruction reconstruction algorithm imaging field of view imaging spatial resolution