青海高原器测时期降水、气温的突变分析     

杨昭明 《成都信息工程学院学报》1998,(2)

对遍及青海高原３８个气象台站器测时期降水和气温分别进行聚类分析,得出３种不同变化类型的降水区域和３种气温区域,然后用ＭＫ突变分析方法和最优二级分割方法对各区域降水和气温气候序列进行均值和方差突变检测得出：青海高原大部分地区在６０年代末出现了降水突变现象,８０年代中后期普遍产生气温突变。  相似文献   

Superwaves and superfloods: The bombardment hypothesis and geomorphology     

R. J. Huggett 《地球表面变化过程与地形》1989,14(5):433-442

The bombardment of the oceans by asteroids and comets leads to the propagation of very large waves—superwaves. On approaching continental margins, superwaves may grow to heights large enough to spill on to the land, flooding extensive areas of continental lowland. The waters from these superfloods, in running back to the sea, would be capable of carrying out enormous amounts of work, possibly diverting rivers, cutting gorges, forming valley meanders, and leading to the widespread aggradation of coarse deposits produced by incoming superwaves stripping the soil and regolith cover and denuding weathered bedrock. Calculations of the magnitude and frequency of superfloods, based on current asteroidal impact rates, indicate that the superflooding of continental margins, including the British Isles, could have occurred several times since the start of the Pliocene. Thus, there seems to be a case for reviving some of the views of the old diluvialists, and exploring the worth of neodiluvialism as a system of Earth surface history.  相似文献   

酒泉地区1937～2001年气候演变及突变分析     

田庆明  马廷德  岳平 《干旱气象》2002,20(3):4-6

利用酒泉地区敦煌、酒泉两气象站 1937～ 2 0 0 1年气温、降水资料 ,分析了酒泉地区气候演变趋势和气候突变期 ,为该区气候决策服务提供参考  相似文献   

基于结构类型和使用功能的建筑分类及其应用     

景冰冰  李小军  陈苏  刘辰  熊政辉 《震灾防御技术》2019,14(2):293-303

基于结构类型的建筑分类是抗震设计和地震灾害分布调查的基础,也是开展建筑结构地震易损性研究所依据的分类形式,而在社会管理中则更注重基于使用功能的建筑分类。上述2种建筑分类方法难以给出恰当的经济损失评估结果,因此在面向地震巨灾保险研究与应用时存在一些不足。首先,传统的建筑分类将建筑的使用功能与结构类型平行处理,未考虑建筑结构类型和建筑使用功能的耦合影响;其次,随着经济社会的发展,建筑结构形式和使用功能均不断地变化,需要发展适用性强大的非固定类型分类方法。本文针对地震巨灾保险业务中建筑分类这一核心问题,结合中国建筑形式和使用功能,从建筑结构分类出发,进一步考虑建筑的使用功能,形成了基于结构类型-使用功能多因素耦合的建筑分类模型,并以北京市典型区域为例,对所提出的建筑分类模型开展应用示范。同时,本文提出的建筑分类模型结合网络信息技术,可解决传统分类应用于具体目标区域时分类指标体系不具备可变性的问题,满足了地震巨灾保险的数据需求。  相似文献   

Regime shifts: Can ecological theory illuminate the mechanisms?   总被引：2，自引：0，他引：2  

Jeremy S. Collie  Katherine Richardson  John H. Steele 《Progress in Oceanography》2004,60(2-4):281

“Regime shifts” are considered here to be low-frequency, high-amplitude changes in oceanic conditions that may be especially pronounced in biological variables and propagate through several trophic levels. Three different types of regime shift (smooth, abrupt and discontinuous) are identified on the basis of different patterns in the relationship between the response of an ecosystem variable (usually biotic) and some external forcing or condition (control variable). The smooth regime shift is represented by a quasi-linear relationship between the response and control variables. The abrupt regime shift exhibits a nonlinear relationship between the response and control variables, and the discontinuous regime shift is characterized by the trajectory of the response variable differing when the forcing variable increases compared to when it decreases (i.e., the occurrence of alternative “stable” states). Most often, oceanic regime shifts are identified from time series of biotic variables (often commercial fish), but this approach does not allow the identification of discontinuous regime shifts. Recognizing discontinuous regime shifts is, however, particularly important as evidence from terrestrial and freshwater ecosystems suggests that such regime shifts may not be immediately reversible. Based on a review of various generic classes of mathematical models, we conclude that regime shifts arise from the interaction between population processes and external forcing variables. The shift between ecosystem states can be caused by gradual, cumulative changes in the forcing variable(s) or it can be triggered by acute disturbances, either anthropogenic or natural. A protocol for diagnosing the type of regime shift encountered is described and applied to a data set on Georges Bank haddock, from which it is concluded that a discontinuous regime shift in the abundance of haddock may have occurred. It is acknowledged that few, if any, marine data are available to confirm the occurrence of discontinuous regime shifts in the ocean. Nevertheless, we argue that there is good theoretical evidence for their occurrence as well as some anecdotal evidence from data collection campaigns and that the possibility of their occurrence should be recognized in the development of natural resource management strategies.  相似文献   

基于多租户的高性能地震保险损失评估SaaS云平台设计与实现     

王小东  粟春晨  宋圣楠  冯键  翟亮亮  熊政辉  马腾飞 《震灾防御技术》2021,16(2):253-262

地震巨灾风险的特点是低频高损,历史震害数据缺乏、风险暴露快速变迁等因素导致基于大数定理的费率厘定方法无法针对各区域不同建筑类型的风险暴露进行精细化定价.本文基于"五代图"潜在震源区模型的随机事件集解决观测数据不足的问题;并使用"五代图"所采用的地震动参数衰减关系模型与工程易损性方法计算地震事件对风险暴露造成的损失,从而...  相似文献   

宁苏扬地区500多年来的旱涝趋势及近期演变特征   总被引：3，自引：0，他引：3  

施宁 《气象科学》1998,(1)

本文采用小波分析等多种统计技术研究了宁苏扬地区1470—1995年间旱涝变化的趋势。500多年可划分为差异显著的6个旱涝气候阶段,进一步还揭示出了在各个旱涝阶段内低频振荡的周期和振幅的不同的特征以及最近一个阶段的旱涝演变特征。  相似文献   

台风强度突变的一个简单模式     

刘式适 《海洋预报》1997,14(4):1-10

本文从描写台风水平运动的基本方程组出发，利用流动稳定性及分岔和突变理论，建立了包含惯性，角动量及气压场等因子的非线性运动模型。  相似文献   

Management and Maintenance of Forestry:A Catastrophic Stochastic Analysis     

M. A. Shah  Usha Sharma 《Natural Hazards》2001,23(1):49-64

In this paper, we have carried out a detailedstochastic analysis of the Ludwig-Jones–Holling modelpertaining to the occasional population burst ofthe spruce budworms in the coniferous forests of Canada.Our analysis explains the abrupt burst of the populationin the form of cusp catastrophe. A qualitative recipe hasbeen suggested for avoiding the catastrophe.  相似文献   

Loss estimation: a powerful tool for risk assessment and mitigation     

F. Bendimerad   《Soil Dynamics and Earthquake Engineering》2001,21(5)

Earlier loss estimation studies were limited to investigating particular scenarios and were carried out by highly specialized experts. Today, loss estimation techniques are translated into efficient software applications that are accessible by a large constituency of end-users. These techniques offer a high level of analysis sophistication and enable users to perform various ‘if–then’ scenarios to study the sensitivity of the results, to develop a better understanding of the outcomes and to gain insight on the consequences of the findings and decisions. Functionality of loss estimation models has improved significantly due to advances in information technology such as the introduction of Geographical Information Systems (GIS). GIS allows for easy display of input and output (in standard reports and maps) providing a critical functionality for communication of outcomes to emergency planners and decision-makers.  相似文献