航空重力确定大地水准面的研究

随着近年来航空重力的发展,航空重力数据的精度和分辨率不断提高,其精度可达1 mGal,分辨率可达10km,这使得用航空重力数据计算精密大地水准面成为可能。本研究介绍利用满足一定条件的稳定、精确的航空重力数据计算大地水准面的一种新途径。它根据布隆公式,分离大地水准面与参考椭球,把航空重力观测值转换为大地水准面上的重力位,从而确定大地水准面。其具体步骤如下: 1.对重力扰动观测数据进行低通滤波,除去高频观测噪声; 2.利用全球重力场模型从低通滤波的重力     

中欧的区域规划:奥地利、德意志联邦共和国、德意志民主共和国和瑞士

区域问题中欧四国和其它发达国家一样存在着一系列区域方面的问题。这四个国家所面临的共同难题是都存在着低收入的边远农业地区的问题。例如,奥地利的东部与高山区,德意志联邦共和国的北部土地贫瘠地区和实际上遍及全国的丘陵地区,德意志民主共和国北部的某些地区以及瑞士的丘陵与山区。这些地区一般的都是地广人稀的。     

Detection of 33.8 Millisecond X-Ray Pulsations in SAX J0635+0533

Recently, detection of discrete features in the X-ray afterglow spectra of GRB 970508 and GRB 970828 was reported. The most natural interpretation of these features is that they are redshifted Fe K emission complexes. The identification of the line emission mechanism has drastic implications for the inferred mass of radiating material and hence the nature of the burst site. X-ray spectroscopy provides a direct observational constraint on these properties of gamma-ray bursters. We briefly discuss how these constraints arise in the context of an application to the spectrum of GRB 970508.     

前寒武纪迭层石的生物地层潜力

引言自化石记录中承认迭层石以来,迭层石在生物地层上的应用具有一定意义。早期的研究者,例如霍尔(Hall,1883)、沃尔科特(Walcott,1914)和芬顿兄弟(Fentons),使用双重命名法来记述迭层石,并出版了古生物资料。早期的研究,例如沃尔科特对于迭层石中保存藻类化石的研究,布莱克(Black,1933)对巴哈马斯(Bahamas)地区现代藻层(mats)的研究,都证明了藻类在造成有机沉积构造中所起的作用。布莱克强     

基于ArcGIS Engine的地震风险预报与评估系统的设计与实现

提出利用ArcGIS Engine技术结合地震相关分析理论进行地震风险预报与评估系统设计,阐述设计原理及优势,并编程实现。系统综合集成地震分析、空间分析、重力分析及统计检验等功能,能有效提高地震风险预测评估一体化程度及震前灾害预警效率,并为地震灾害预警研究提供参考。     

微型顶管中管-土间相互作用的分析

采用物理模型试验和数值模拟的方法对顶管过程中的管一土相互作用进行了分析。在将数值分析与模型试验的结果进行比对校准之后,运用有限元分析程序ABAQUS对顶管过程中的地表沉降、破坏机制和管-土相互作用等问题进行了研究。分析结果表明作用于开挖面上的推力对于顶管是至关重要的：推力过小是造成地表沉降的主要原因;而推力过大则会引成地表隆起。此外,研究结果还表明管道的埋深对于选取合理的推力以及确保开挖面的稳定是十分关键的。     

Data selection using support vector regression

Geophysical data sets are growing at an ever-increasing rate, requiring computationally efficient data selection(thinning)methods to preserve essential information. Satellites, such as Wind Sat, provide large data sets for assessing the accuracy and computational efficiency of data selection techniques. A new data thinning technique, based on support vector regression(SVR), is developed and tested. To manage large on-line satellite data streams, observations from Wind Sat are formed into subsets by Voronoi tessellation and then each is thinned by SVR(TSVR). Three experiments are performed. The first confirms the viability of TSVR for a relatively small sample, comparing it to several commonly used data thinning methods(random selection, averaging and Barnes filtering), producing a 10% thinning rate(90% data reduction), low mean absolute errors(MAE) and large correlations with the original data. A second experiment, using a larger dataset, shows TSVR retrievals with MAE < 1 m s-1and correlations 0.98. TSVR was an order of magnitude faster than the commonly used thinning methods. A third experiment applies a two-stage pipeline to TSVR, to accommodate online data. The pipeline subsets reconstruct the wind field with the same accuracy as the second experiment, is an order of magnitude faster than the nonpipeline TSVR. Therefore, pipeline TSVR is two orders of magnitude faster than commonly used thinning methods that ingest the entire data set. This study demonstrates that TSVR pipeline thinning is an accurate and computationally efficient alternative to commonly used data selection techniques.     

THE STABILITY OF ROCK-VENEERED HILLSLOPES

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