Statistics on the vertical structure of rainshowers

A large sample of summertime data from the McGill Radar Weather Observatory was analyzed to determine the variation with altitude of the horizontal extent of individual rainshowers. For echoes defined by a reflectivity factor of 39 dBz (equivalent to a rainfall rate of about 10 mm/h) it was found that the mean area of the total population of echoes decreases linearly with altitude from approximately 20 km² at 2 km to 11 km² at 8 km. Subsets of the total population were investigated, consisting of only the echoes penetrating the altitudes of 6, 7, and 8 km. On the average these relatively tall echoes are much greater in horizontal extent than the total population. Whereas the sizes of the total population of echoes at any altitude are distributed approximately exponentially in terms of the square root of area, the sizes of the “survivors” that extend to high altitudes may be described by the gamma distribution with a mean value decreasing approximately linearly with height above 3 km and a dispersion of 0.55. Some characteristics are also reported for echoes defined by reflectivities of 31 dBz and 47 dBz. Estimates are given of the fraction of the total area in a horizontal plane that contains echoes in each of these categories.     

Hypotheses for earthquake occurrences

Very little work has been done in generating alternatives to the Poisson process model. The work reported here deals with alternatives to the Poisson process model for the earthquakes and checks them using empirical data and the statistical hypothesis testing apparatus. The strategy used here for generating hypotheses is to compound the Poisson process. The parameter of the Poisson process is replaced by a random variable having prescribed density function. The density functions used are gamma, chi and extended (gamma/chi). The original distribution is then averaged out with respect to these density functions. For the compound Poisson processes the waiting time distributions for the future events are derived. As the parameters for the various statistical models for earthquake occurrences are not known, the problem is basically of composite hypothesis testing. One way of designing a test is to estimate these parameters and use them as true values. Momentmatching is used here to estimate the parameters. The results of hypothesis testing using data from Hindukush and North East India are presented.     

局部重磁场源全方位成像理论概要(续)

作者近年来首创了"复杂条件下局部重磁场源全方位成像"理论体系。在本文中,概要阐述该理论体系中下延有限二度体复重磁场级数正演通式、复场模值全方位延拓和全方位反演等。     

新形势下测绘保密工作的思考

在《中华人民共和国测绘成果管理规定》及其相关的管理规定中 ,对基础测绘成果保密等级的划分、调整和解密都作了详细的规定。但是在新形势下 ,现行保密法规的对象发生了变化 ,传统的保密管理方式已不适用 ,因此 ,应在保守国家核心机密的前提下 ,重新审定各种地理信息产品的密级 ,最大限度地扩大流通服务范围 ,使地理信息能更多更好地为国民经济建设服务     

建设数字地震 促进防震减灾

本文提出了“数字地震”的概念 ,讨论它的主要内容和问题 ,并对建设“数字地震”提出若干建设性意见。     

中小震近场地震动估计中地震动衰减关系的适用性分析

核工程场地设计基准地震动确定中涉及弥散地震的地震动估计，这导致中小震近场地震动估计成为被关注的研究课题。本文基于一些中小震近场地震动记录资料，分析和探讨了国内外多种地震动衰减关系对中小震近场地震动估计的适用性问题，并结合我国几个核工程地震问题研究工作的实践对中小震近场地震动衰减关系确定的思路和原则提出了建议。     

地震定位研究及应用综述

地震定位是地震学中最经典、最基本的问题之一，提高定位精度也一直是地震学应用研究的重要课题之一。本文就目前各种地震定位方法进行了大体分类并概述了基本原理及其应用，介绍了目前在国内各实时地震观测系统中应用的台网定位方法，同时将部分台网方法应用于黑龙江省绥棱爆破的定位。     

土木工程结构的双层多重调谐质量阻尼器控制策略

为能得到用尽可能少的调谐质量阻尼器(TMD)组成有效性和鲁棒性高的多重调谐质量阻尼器控制系统，本文提出了一种适用于土木工程结构的新控制策略——双层多重调谐质量阻尼器(DMT—MD)。使用定义的优化目标函数，评价了双层多重调谐质量阻尼器(DMTMD)的控制性能。数值结果表明，双层多重调谐质量阻尼器(DMTMD)比多重凋谐质量阻尼器(MTMD)具有更好的有效性和对频率调谐的鲁棒性。DMTMD比双重调谐质量阻尼器(DTMD)具有更好的有效性，而DMTMD和DT—MD对频率调谐的鲁棒性近似相同。因此，双层多重调谐质量阻尼器是一种先进的结构控制策略。     

油气储运系统钢结构设备地震火灾效应研究

预防和减轻油气储运系统地震火灾危险性是防震减灾中的重要课题。本文论述了油气储运系统的地震火灾特征及防火要求，对钢结构的防火涂料在遭到破坏和平时情况下的抗火性能进行了对比分析，并应用有限元法对油气储运系统中典型钢结构设备在地震火灾荷载作用下的抗火性能进行了数值模拟。研究结果表明，防火涂料遭到强地震荷载破坏后，钢结构的抗火性能大大降低。     

印尼8.7级地震前银川台形变数字化观测资料短临异常特征分析

采用形变观测资料分析方法中比较常用的形态法、差分法、消除潮汐改正和零漂法，处理了银川台形变数字化观测资料，发现在印尼8．7级地震前出现了一些短临异常情况，并对异常的变化特征做了相应的分析。