FIR-RD快视算法方位向二维频谱匹配流程的改进

为了实现星载SAR快视处理的实时性,根据星载SAR数据FIR-RD快视成像算法的特点,分析了距离徙动校正对方位向匹配的影响.针对快视成像最耗时的方位向匹配流程,根据方位向匹配矩阵参考函数的特点,提出了方位向二维匹配处理的改进方法.实验结果表明,运算量降为优化前运算量的1/10,实现了快视系统的实时处理.     

星载高分辨聚束模式SAR数据干涉处理

数字高程模型（DEM）在很多地形应用,如三维地形图绘制、区域建设、环境保护和灾害预防方面起着越来越重要的作用。长期以来DEM的获取依赖于人工或光学方法进行测量,但这受到测绘区域、测绘时间和天气状况等诸多因素的制约。合成孔径雷达（SAR）的出现极大地帮助解决了上述的制约问题。通过合成孔径雷达会获取SAR图像进行干涉测量可以较为方便地得到待测场景的高程信息,特别是聚束SAR模式（spotlight SAR mode）解决了传统条带模式下低分辨率的问题。然而,通过传统的干涉处理方法处理聚束SAR会带来方位向残余条纹和大量的相位无解区域影响DEM生成。针对传统的SAR干涉处理方法无法解决高分辨聚束模式下的DEM反演问题,就此提出了一种新的基于多普勒中心频率估计进行配准和联合相位解缠的星载高分辨聚束模式SAR数据干涉处理方法,通过新的处理方法对TerraSAR-X高分辨聚束模式的数据进行处理,详细阐述了从数据配准到地理编码的各个处理环节,并将处理结果与传统处理方法的结果进行比较,显示出了较好的DEM反演结果。     

对聚束和滑动聚束模式下星载合成孔径雷达的旁瓣侦察比较研究

聚束模式是合成孔径雷达常用的工作模式,聚束模式的精度高,在军事上发挥着很大的作用。滑动聚束模式是一种新兴的工作模式,它有着比条带模式分辨率高,比聚束模式成像区域大的优点,因此受到广泛的利用和研究,文章在此基础上,根据合成孔径雷达的特点,展开了对合成孔径雷达的侦察研究,并比较分析了星载合成孔径雷达工作模式的侦察,仿真实验验证了可行性。     

基于ENCS的FMCW SAR俯冲聚束成像方法

针对弹载调频连续波合成孔径雷达FMCW SAR俯冲聚束成像的特点,通过构造全时间距离走动校正函数,完成了距离走动校正;采用谱分析的方法进行方位多普勒解模糊处理,消除方位向频谱混叠;在方位向处理中,提出一种改进的非线性调频变标算法,补偿方位空变相位误差,实现了方位向的精确聚焦.点目标仿真实验验证了理论分析与所提成像方法的有效性.     

大椭圆轨道SAR滑动聚束模式设计及斜距模型

针对大椭圆轨道合成孔径雷达存在大偏心率,时变轨道高度及时变卫星速度等特性,首次开展了大椭圆轨道SAR滑动模式设计研究.对大椭圆轨道SAR滑动聚束模式设计,考虑了不同轨道位置处不同分辨率改善因子、地面波束足迹一致性、天线扫描角度、天线扫描角速度等.对大椭圆轨道SAR滑动聚束模式回波斜距模型研究.仿真分析结果表明大椭圆轨道SAR滑动聚束模式参数需要随轨道位置变化进行调整,为了满足成像需求斜距模型需要展开到三阶.      

综合因素下的星载SAR模糊函数分析

综合考虑地球自转、地球曲率以及卫星轨道等因素,建立了星载合成孔径雷达（synthetic aperture radar,SAR）卫星绕地飞行模型,推导了星载SAR模糊函数的表达式。通过对模糊函数进行分析,表明模糊函数与地球自转、地球曲率及卫星轨道因素有关。为验证理论推导结果,对卫星位于不同赤纬(卫星与地心连线和赤道面的夹角)照射地面目标情况进行了仿真分析,仿真结果表明：对比传统模糊函数,地球自转和卫星观测位置会使星载SAR的模糊函数分辨单元轴有一定的偏转,而地球曲率和卫星圆轨道会影响星载SAR模糊函数所表示的分辨率,在合成孔径时间较长或卫星侧视角较大的情况下表现得更为明显。     

星载合成孔径雷达实时快视成像系统

给出了一种基于多数字信号处理(DSP)并行处理技术的星载合成孔径雷达(SAR)快视成像系统设计,比较了多种星载SAR成像算法.针对某星载SAR参数提出了优化的实时算法流程,系统实现了对L波段星载SAR距离向1/4降分辨率和方位向四视实时成像处理.通过仿真和实测数据,分析和验证了系统成像结果.     

机载聚束式SAR的实时成像算法

聚束式SAR适用于小场景成像,目前聚束式SAR的成像算法有很多,基于实际系统中实时性的要求,可采用S-RD算法来完成对目标的成像．由于成像区域较小,距离徙动的影响较小,成像算法可分维处理．在距离维,采用去斜技术对回波进行处理,实现脉冲压缩;在方位维,用方位向匹配函数实现方位向聚焦,最后计算该算法的运算量．试验结果表明：该算法步骤简单,运算量小,可被应用于实际系统中完成对目标的实时成像．     

基于SSC的星载SAR有源干扰方法

 不同干扰方式对星载SAR的干扰效果主要取决于干扰信号与SAR回波信号的相似度,即干扰信号在信号结构和特征方面与星载SAR回波的相似程度。通过提出一种基于散射统计特性（SSC）的星载SAR有源干扰方法,构建用于干扰星载SAR的类杂波信号数学模型,分析该信号与星载SAR回波信号的散射统计特性相似度,并进行了仿真分析。仿真结果表明该方法在相同的干信比下有更好的干扰效果,具有较好的应用前景。     

一种新的双基阵纯方位机动目标跟踪算法

针对方位测量方程的非线性问题，提出了一种基于改进的自构建神经模糊网络（SONFIN）的双基阵纯方位机动目标跟踪算法。该算法首先利用目标方位角信息，对其进行目标特征提取，然后利用小波基函数所具有的时频局部分析能力，提出了用小波基函数来代替高斯基函数这一策略。仿真结果表明，神经模糊网络可实现双基阵纯方位机动目标的实时跟踪，并且改进后的网络跟踪性能要优于高斯基网络。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to