分析研究基于小波分析与谱分析提高重力异常的分辨能力   总被引：5，自引：14，他引：5       下载免费PDF全文

邱宁  何展翔  昌彦君 《地球物理学进展》2007,22(1):112-120

重力数据是所有地下场源产生的重力场的叠加，探测对象经常被淹没在区域背景场之中，因此剩余异常的分离对于重力资料研究至关重要，而近来被引入位场领域的小波算子作为了滤波器和场源分析工具，在这里我们分析研究基于小波分析与谱分析的二维离散小波变换用于提高重力异常的分辨能力，再现出由简单形状场源描述密度不均匀的几何特征.本文先介绍二维多分辨率分析小波的基本理论及其提升算法，利用对数功率谱估计平均深度方法理论，接着对理论模型数据进行多尺度异常分解，估计地质体的形状、大小和深度，最后又对实测重力数据进行分析，并与传统常规方法进行比较分析，结果表明对于实际数据分析其方法也是具有可行性的.  相似文献   

基于提升格式小波包变换的SAR图像去噪     

王文波  费浦生  羿旭明  张建国 《武汉大学学报(信息科学版)》2007,32(7):585-588

基于信号和噪声在提升格式小波分解中呈现出的不同特性，提出了一种新的小波包去噪算法。该算法采用提升格式小波对SAR图像进行最优小波包分解，并计算每个子频带的能量范数，然后根据软阈值法和能量范数区分信号和噪声，达到去除噪声的目的。试验结果表明，该算法对SAR图像具有较好的去噪效果，不仅可以去除图像中的大部分噪声，而且可以较好地保留图像纹理的细节信息。与传统小波包算法相比，其计算速度快了一倍左右。  相似文献   

第2代双正交小波的上升型构造及其应用   总被引：1，自引：1，他引：1  

张建军施全杰  耿则勋 《测绘学院学报》2003,20(2):106-109

介绍了双正交小波分解的基本理论，并用数字滤波器的观点分析了双正交小波函数所满足的条件；讨论了双正交小波函数及滤波器的上升型构造方案，在此基础上从最简单的Haar小波基出发，通过上升型步骤构造出具有不同特性的第2代双正交小波数字滤波器；最后给出了基于第2代双正交小波变换的图像放大算法及实验结果。  相似文献   

青藏铁路基础桩孔施工用旋挖钻具的研究   总被引：3，自引：0，他引：3  

于好善 《探矿工程》2003,30(4):1-3

根据青藏铁路采用旋挖钻进施工的特点，研制出适应青藏铁路各种地层条件的旋挖钻具，并制定出一套科学的旋挖钻进工艺，从而解决了青藏铁路桥桩基础施工这一世界难题，也为实现旋挖设备和钻具国产化打下良好基础。  相似文献   

Analysis of Meteorological and Terrain Features Leading to the Izmir Flash Flood, 3–4 November 1995     

Kömüşçü  Ali Mümran 《Natural Hazards》1998,18(1):1-25

Flash floods associated with heavy precipitation has become a hazardous phenomenon along the Mediterranean coasts of Turkey in recent years. During 3 and 4 November 1995 heavy and intense rainstorm activity over the Aegean coast led to flash flooding in the city of zmir. Damage exceeded $50 million and 61 people died as a result of the flood. The Karyaka district suffered the most severe damage. This study presents an analysis of the meteorological settings that led to the development of these intense storms and describes the role of the terrain features involved in the zmir flood.The important mesoscale features which initiated the severe weather outbreak included pronounced low-level advection, positive vorticity and strong upper level divergence. A surface low centered over the Aegean Sea enhanced the advection of warm and moist unstable air masses coming from the southwest over the Mediterranean Sea along a southwesterly low level jet (LLJ). A squall line oriented NE-SW over the Aegean Sea also contributed to the storm development, and intensity of the storms was further enhanced by the orographic effect. The presence of a frontal system, the stability indices associated with the event, and other meteorological features are all reminiscent of the synoptic type flash floods identified by Maddox. While the pressure and moisture patterns were favorable for severe storm activity, nonmeteorological factors including the topography, geomporphology, and and land-use contributed to the flooding to a great extent. Settling in the flood-prone zone, insufficient floodwater structures, and the lack of channel improvements in the creeks enhanced flood damage to the city. Many of the deaths occurred in the settlements located in the flood-prone zone of the Ilca and Dallk creeks.  相似文献   

Dynamic characteristics of spring sandstorms in 2000   总被引：11，自引：0，他引：11  

周秀骥  徐祥德  颜鹏  翁永辉  王建林 《中国科学D辑(英文版)》2002,45(10):921-930

Systematical analyses of spring sandstorms in 2000 affecting Beijing area are carried out. Results revealed the key dynamic mechanisms of dust storm during its mobilization, lifting, horizontal advection and deposition processes. It turns out that in the processes of sandstorms influencing Beijing area in March–April 2000, the dynamic conditions for dust mobilization are significantly correlated with phenomena, such as cold air-related climatic activities, clay soils area of North China and surface friction velocity anomaly. The characteristics of sandstorm can be described by composite mode of dust particles mobilization-lifting-long-range transport. This paper will provide scientific evidences for further studies, prediction and harness of sandstorms in China.  相似文献   

Laboratory simulation of clast abrasion     

J. Lewin  P. A. Brewer 《地球表面变化过程与地形》2002,27(2):145-164

Experimental abrasion of river‐bed materials has been widely undertaken, producing ‘downstream’ fining rates that generally are believed to be much less than those observed in the field. A conclusion commonly adopted has been that sorting processes are more effective than abrasion processes. A comparative evaluation of results from an abrasion tank and a tumbling barrel are presented, which show that abrasion patterns and rates differ according to the equipment used, clast size and shape, the clast charge (barrel) and water velocity and bed material (tank). Abrasion is a composite process, and the effects achieved appear to be dominated by percussion in the tank and grinding in the barrel. Breakage, crushing and sandblasting are not modelled effectively, nor are effects achieved on clasts when they form part of the bed. Comparisons are made with other equipment used, the very limited amount of direct field abrasion monitoring, and with the probable suite of processes that may occur under field conditions. Also reviewed are the problems that arise when laboratory weight‐loss abrasion coefficients are used or converted into ones of size diminution, as usually derived from field observations of down‐channel trends. It is concluded that field abrasion rates generally have been underestimated, as the processes involved are at best only selectively represented by the experimental equipment so far used, and because the results obtained experimentally are capable of misinterpretation when related to field trends. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

重磁场多尺度分析原理   总被引：1，自引：0，他引：1  

李健  周云轩  卢焱 《世界地质》2000,19(4):379-384,391

介绍了连续小波变换,离散小波变换,框架理论和多分辨分析（多尺度分析）等小波分析的基本方法原理以及第二代小波（升降方案）,以及近年来小波分析在重磁场中的应用成果（包划常识别,异常分离,信号云噪,重磁下延,反演成像等方面）。在对其进行仔细分析的基础上,指出目前小波分析在重磁场领域应用中存在的问题,诸如如何选择一个较优的小波母函数,并提出相应的解决思路－模型小波。  相似文献   

HZ308多功能取心钻具在某金矿区的应用效果          下载免费PDF全文

胡中立 《探矿工程》1995,(2):23-24

通过ＨＺ３０８多功能取心钻具有蚀变岩型和石英脉型金矿地层的应用，提出了防止底喷分流式钻头堵心、减少其损耗的措施。  相似文献   

多功能地质勘察平台关键结构设计与应用   总被引：3，自引：3，他引：0       下载免费PDF全文

宋宝杰  王鲁朝  栾东平  孙晓玉 《探矿工程》2017,44(11):46-49，56

本文结合小型简易式平台、“探海1号”大陆架科学钻探平台等设计建造应用的经验,对多功能地质勘察平台模块化连接、升降模块以及桩靴等关键结构进行设计及应用,创新设计解决了平台建造场地限制、运输、方便安装等问题,提高了平台升降、迁移的效率,以适应短周期、需频繁移动平台的海上工程勘察项目。通过实际应用效果良好。  相似文献