基于斜投影算子的雷达有源压制干扰抑制

根据斜投影具有区分位于不同信号子空间中信号成份能力的特点,针对单阵元接收的常规体制脉压雷达,探讨了斜投影算子在雷达抗有源压制式干扰中应用的可行性.借助原子分解的思想,得到了信号模型中的模式矩阵H与S.仿真结果表明该方法可以有效对抗有源压制式干扰.     

斜投影算子Moore-Penrose逆的表示（英文）

基于空间分解的方法和技巧给出了希尔伯特空间中斜投影算子Moore-Penrose逆的矩阵表示.应用该矩阵进一步讨论并得到了两个斜投影算子的差的Moore-Penrose逆的存在条件和矩阵表示,使得斜投影算子的Moore-Penrose逆的结构更加清晰.     

正交投影三维极化滤波

针对干扰和目标极化状态在Poincare球面距离很近的情况下,二维虚拟极化滤波失效的问题,提出了基于正交投影的三维极化滤波方法。该方法在传统三维极化滤波的基础上重新明确了问题的限定条件,给出了干扰抑制准则下干扰正交子空间中的一组完备正交基,这组正交基物理意义清晰,便于算法的深入扩展。在求得的子空间内,得到了干扰抑制准则下,使目标回波接收功率最大的权系数矢量,理论及仿真结果表明,文中所提算法充分挖掘了目标和干扰在极化域与空域的特性差异,算法性能较传统方法有明显改善。     

极化滤波器的性能评估与选择

根据不同的电磁环境合理选择极化滤波器,对于极化滤波效果具有重要的影响. 以信号干噪比极化滤波器为参照标准,提出了极化滤波器性能的度量方法和评价指标. 在此基础上,针对干扰抑制极化滤波器和信号匹配极化滤波器这两种最常见的极化滤波器,提出了优选方案和判别条件.     

斜投影乘积交换性的一些等价刻画

用算子矩阵分块技巧研究复Banach空间上两个斜投影乘积的交换性, 通过两个斜投影的和、 差、 积等几种代数组合的{1}-,{1,5}-,{2,5}-逆和群逆给出两个斜投影乘积可交换的等价刻画.     

一类次正规算子的换位之提升

证明了具有极小酉扩张的次正算子炎换位具有提升，且投影算子可以提升为投影（其中投影算子可以是正交投影，也可以是斜投影）。     

调零天线中的空域极化域联合抗干扰算法

在期望信号功率较小情况下,强同频干扰容易造成系统灵敏度下降,比如卫星导航和卫星通信。采用一个4阵元正交极化阵列,可以通过空域和极化域联合方式对干扰进行抑制。阵列参考阵元位于圆心,其余3个阵元均匀分布在圆周上。自适应滤波采用功率倒置准则下的 LMS算法,该方法调整每个正交极化阵元权系数,使得阵列在干扰极化下等效的极化匹配因子接近为0,实现干扰抑制。算法无需信号空间信息,实现简单,同时使阵列自由度达到6,从而增加抗干扰个数。计算机仿真证明了4个阵元阵列可以有效抑制最多6个干扰,而且,通过极化域处理,即使干扰信号与期望信号入射角度相同,只要极化不同,也可以抑制干扰而保持对期望信号增益。     

煤层槽波的极化特征及其滤波

文章利用多分量数值模拟获得槽波信号及其极化轨迹图,结合槽波信号的本征方程,求取槽波的主极化方向和偏振系数;选取Poline滤波器,采用不同的滤波参数(p,q)对正演模拟信号进行滤波处理,并用极化轨迹图直观地显示出滤波前后差异。由于极化滤波实质是一种振幅加权滤波,滤波参数控制了信号对于其主极化方向的趋近程度,因此极化滤波会造成各分量的能量损失,需综合考虑选择合适的滤波参数。文中利用极化滤波法对实测信号进行了处理,取得了良好的应用效果。     

视觉导航智能汽车路径识别图像处理算法研究

复杂环境下图像快速准确处理是智能汽车稳定运行的前提和保证.该文针对由于光线等因素造成图像对比度不明显问题,提出了线性变换方法处理图像;针对由于图像边缘点的干扰而造成中位数处理失败,提出了中值滤波和T型窗口算法;基于Roberts算子的高精度和Sobel算子的高运算效率,提出了一种融合两种算子的融合算法用以改进边缘检测算法.实际应用表明,上述算法可以过滤边缘噪音,有效地去除干扰噪音,过滤后整幅图像的边缘更连续平滑,融合算法的计算量远远小于单一算子,算法的实时性和准确性大幅提高.     

FIR小波预后滤波器的设计及其性能分析

针对一般双正交紧支撑小波，设计出较简单的ＦＩＲ预后滤波器，并对其逼近性能进行了分析，获得了预滤波算法逼近误差的渐近公式，结果表明，预滤波算法与斜投影具有相同的逼近性能，最后的模拟结果与理论分析是一致的。     

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