基于小波变换的信号突变检测滤波和瞬态谱研究

该文简述了小波理论产生的背景和发展过程,详细介绍了小波变换的概念、基本特性以及基于小波变换的信号突变检测、滤波及基于小波包变换的瞬态谱研究方法和结果。文后对小波变换在地震信号处理中的应用前景进行了讨论。     

A GIHS-based spectral preservation fusion method for remote sensing images using edge restored spectral modulation

High spatial resolution and spectral fidelity are basic standards for evaluating an image fusion algorithm. Numerous fusion methods for remote sensing images have been developed. Some of these methods are based on the intensity–hue–saturation (IHS) transform and the generalized IHS (GIHS), which may cause serious spectral distortion. Spectral distortion in the GIHS is proven to result from changes in saturation during fusion. Therefore, reducing such changes can achieve high spectral fidelity. A GIHS-based spectral preservation fusion method that can theoretically reduce spectral distortion is proposed in this study. The proposed algorithm consists of two steps. The first step is spectral modulation (SM), which uses the Gaussian function to extract spatial details and conduct SM of multispectral (MS) images. This method yields a desirable visual effect without requiring histogram matching between the panchromatic image and the intensity of the MS image. The second step uses the Gaussian convolution function to restore lost edge details during SM. The proposed method is proven effective and shown to provide better results compared with other GIHS-based methods.     

Equilibrium Structures of Differentially Rotating and Tidally Distorted White Dwarf Models of Stars

In this paper we present a method for computing the equilibrium structures and various physical parameters of a primary component of the binary system assuming that the primary is more massive than the secondary and is rotating differentially according to the law of the w² = b₀ + b₁ × s² + b₂ × s⁴, w being the angular velocity of rotation of a fluid element distant s from the axis of rotation and b₀, b₁, b₂ suitably chosen numerical constants. This method utilizes the averaging approach of Kippenhahn and Thomas (1997) and the concept of Roche equipotentials in a manner earlier used by Mohan et al. (1997) to incorporate the effects of rotation and tidal distortions on the equilibrium structures of certain rotationally and tidally distorted stellar models. The use of the method has been illustrated by applying it to obtain the structures and some observable parameters of certain differentially rotating and tidally distorted binary systems whose primary component is assumed to be a white dwarf star.     

单基准线向量解算法在GPS变形监测中的应用

GPS测量目前在三峡库区变形监测应用较为广泛,但常规数据处理中,网平差这一步骤导致了因某点测量误差偏大而导致的整个监测网中其他监测点测量误差偏大,为解决这一问题,介绍了单基线向量解算法,并利用该方法对长屋滑坡2005年3月-2007年3月的监测点数据进行解算,提出了该方法能减少测量误差和内业工作量,并能运用于实际工程。     

2-D or 3-D interpretation of conductivity anomalies: example of the Rhine-Graben conductivity anomaly

Summary. Evidence of a conductivity anomaly in the Rhine-Graben was first given about 15 years ago and consequently led to the definition of various models of induction in the region for periods ranging from a few minutes to a few hours. These models reflect two antagonistic ways of explaining the observed anomalous variations of the magnetic field: direct induction in a two-dimensional (2-D) structure or static distortion of telluric currents by the resistive crystalline Vosges (France) and Schwarzwalde (Germany) massifs. We discuss the two approaches using a simple formalism. In particular, we show that the self-induction related to the anomalous currents flowing in the Rhine-Graben is negligible for periods larger than 1000 s, and that, even though the static distortion of telluric currents does account for the observed anomaly, 2-D models can explain some of its features. We also show how the channelled currents are induced in the large sedimentary basins surrounding the area under study.
An experimental verification of this result is given.     

On minimum spanning trees and the intergradation of clusters

Cluster analysis groups samples, but does not generally show gradations between clusters. To illustrate these relationships, principal-coordinate analysis and multidimensional scaling can be employed, but these methods may not be appropriate due to structural distortion. A minimum spanning tree (MST) computes a point-to-point path through the original matrix, and clusters are mapped on the MST diagram. The MST linkages, therefore, provide a natural continuum between the clusters, without distortion. Forty-six Silurian Tonoloway Limestone samples were analyzed for 16 sedimentary features indicative of subaerial exposure. Cluster analysis identified nine clusters which were reduced to five final, ordered groups by MST.     

Henry Darcy in his own words

A recently published English translation of the Les Fontaines publiques de la ville de Dijon 1 provides access to Henry Darcy's own words on the importance of water for public sanitation and on questions engineers face in building water supply systems. Written near the end of Darcy's life, the book is a compendium of the water knowledge he had gained over decades and his opinions on these topics reveal his personality. In the 1840s, Darcy built a water supply system to provide water to 120 street fountains for domestic purposes, street washing and firefighting. Surrounded by poverty, Darcy insisted on free water for the poor and on sharing the spring water with towns located along the aqueduct that brought it to Dijon. In the preface to the book, Darcy introduces his experiment on water flow through sand with the modest words “to my knowledge, no one has experimentally demonstrated the laws of water flow through sand.” This article provides a sampling of the book's insights into the personality of this remarkable man.

中国海岸带专用地图投影设计

地图投影是各类海岸带信息的空间定位框架要素之一。通过对目前我国海岸带常用的各种地图投影现状分析,设计并实现全国海岸带专用投影———斜轴等角圆锥投影,该投影不仅使得整个中国海岸带实现无缝的一体化表达,而且使变形达到最小。文中详细阐述该投影的设计思想和设计原理,并将结果与其他各种海岸带投影进行详细的分析比较。     

琅岐闽江大桥测量坐标系统的建立与精度分析

介绍了琅岐闽江大桥的概况,阐述了大桥测量坐标系统建立的原理以及转换参数求解的方法,分析了转换参数的精度,结果证明完全满足设计和施工的要求。