Comparative Studies on the Harm Characteristic of Hot-dry wind and High Temperature Heat Waves     

Deng Zhenyong  Zhang Qiang  Xu Jinfang  Chen min  Qin Sanjie  Zhang Shuyu 《地球科学进展》2009,24(8):865-873

This paper summarized six aspects such as the harm characteristics, type and index, climatic characteristics, causes, responding to globe changes, protecting technology and answering tactics of hot-dry wind and high temperature heat wave. There is distinction and relationship between hot dry wind and high temperature heat wave. This includes that both of hot-dry wind and high temperature heat wave belong to serious shorter time scale weather disasters. Lower humidity and higher temperature are their main characteristics. The two causes of abnormal circulation characteristics and impacts of the disasters from climate change are basically the same. The disasters may occur in the same area during the same period. Arid season is helphul for their development and aggravation damage. There are differences on harm characteristics, type and index, climatic characteristics, protecting technology and answering tactics in this two weather disasters in that the high temperature heat wave is the comprehensiveness meteorological disasters and dry-hot wind is the agrometeorological disasters.  相似文献   

河西内陆河流域水资源可持续利用研究     

陈文 《地下水》2009,31(6):71-73

河西内陆河流域水资源短缺、水污染和生态环境恶化已成为经济社会可持续发展的重要制约因素。通过分析研究河西内陆河流域水资源现状、水资源特点、水资源需求变化过程以及社会经济发展对水资源的需求,提出实现水资源可持续利用的措施和对策,为河西地区经济社会可持续发展提供水资源保障。  相似文献   

退耕还林还草研究之进展   总被引：14，自引：4，他引：10  

孙霞  尹林克  孟林  白根本  王雷涛 《干旱区地理》2004,27(2):221-224

在综合阐述我国自实行退耕还林还草以来有关退耕的研究成果及存在的问题之时,比较分析了中外退耕还林还草实践中的退耕目的、基础及政策方面的差异。并针对目前国内退耕研究存在的问题和不足,提出应加强除坡耕地以外的其他类型耕地的退耕和对退耕适宜性评价的研究,大尺度区域范围内采用先进的遥感和地理信息技术的研究方法和手段将是今后退耕还林还草规划和决策分析的重要手段。  相似文献   

中国中部农区企业集群的竞争优势研究--以河南省虞城县南庄村钢卷尺企业集群为例   总被引：17，自引：3，他引：14  

李小建  李二玲 《地理科学》2004,24(2):136-143

中国中部农区企业集群的竞争优势来源既具有一般企业集群的共性——它是规模经济、分工经济和网络联系三者共同作用的结果,又具有其特殊的个性——模仿创新的普遍发生、中原文化背景、制度扶持和较低的劳动力、土地等要素成本起决定作用。以河南省虞城县南庄村钢卷尺企业集群为例,详细分析了中国中部农区企业集群竞争优势的内在来源。  相似文献   

中国大陆地壳运动的GPS观测及相关动力学研究   总被引：12，自引：6，他引：6  

熊熊  滕吉文  郑勇 《地球物理学进展》2004,19(1):16-25

现代空载大地测量技术的发展极大地改变了传统大地测量学的观测手段、研究内容和范围,促进了地球动力学领域的研究．本文回顾过去近二十年来在中国大陆进行的全国及区域性GPS观测和取得的成果,重点评述在GPS相关动力学领域的研究进展和存在的问题,对我国GPS观测及动力学研究今后的发展提出初步见解．  相似文献   

非饱和土热力学参数确定的探讨   总被引：2，自引：1，他引：1  

卢应发  吴延春  杨丽平  崔玉军 《岩土力学》2008,29(7):1747-1752

研究非饱和土热力学的力学性质,必须建立能量守恒方程,表征能量的两个基本物理力学参数（体积比热系数和热传导系数）的确定是求解能量守恒方程的重要因素。对于不同颗粒组成的土体,对其干燥颗粒有效热力学参数进行了分析,对固体、液体和气体三相共存的热力学参数进行了研究,并对计算结果进行了对比分析,在此基础上,提出了较适合计算热传导系数的方法,并将此方法和体积平均法、自洽法及Hashin-Strikman方法进行了比较。经与试验结果对比表明：提出的方法能较好地描述非饱和土的热力学参数特性。  相似文献   

深层软基加固处理方案试验研究   总被引：1，自引：0，他引：1  

杨建民 《岩土力学》2008,29(7):1981-1986

在软土地区既有铁路线旁修建复线时,为控制施工期沉降与工后沉降,保证既有线路与新建线路的稳定性,对新建复线的深层软基加固区,通过现场试验采用6种方法分7个观察项目进行了对比研究。试验结果表明：无论是沉降分析、稳定分析或是对既有线的影响分析,用粉喷桩加固地基比用砂井、插塑板及土工布加固地基均有着显而易见的优越性,相对来说短而密的粉喷桩较长而疏的粉喷桩加固效果更好。  相似文献   

A parametric and comparative study of different tephra fallout models     

S. Scollo  A. Folch  A. Costa 《Journal of Volcanology and Geothermal Research》2008

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Vesiculation and crystallization under instantaneous decompression: Numerical study and comparison with laboratory experiments     

A. Toramaru  T. Miwa 《Journal of Volcanology and Geothermal Research》2008

Vesiculation and crystallization in ascending magmas are key processes that control the eruption behavior, and they interplay each other through the water exsolution process. We conducted a numerical study in order to quantitatively understand the water exsolution and crystallization processes in natural eruptions (decompression history is unknown) and in laboratory experiments (the amount of decompression is constant with time). The numerical results, which take into account homogeneous or heterogeneous nucleation and growth of bubbles with varying diffusivity of water, viscosity, and the amount of decompression, provide a quantitative understanding of their control on bubble formation and water exsolution in the constant amount of decompression. The bubble nucleation in the homogeneous nucleation can be divided into two regimes – the diffusion control regime and viscosity control regime – depending on the modified Peclet number and the effective supersaturation. In the cases of both homogeneous and heterogeneous nucleations, the bubble growth is controlled by diffusion or viscosity, depending on the modified Peclet number and bubble number density. The water exsolution rate, which is controlled by the modified Peclet number in the viscosity control regime and by the bubble number density and diffusive driving force in the diffusion control regime, acts as an effective cooling rate in a decompression-induced crystallization process. A comparison of the numerical results with the results of laboratory experiments suggests that water exsolution proceeds by the diffusion-limited growth of bubbles under disequilibrium vesiculation through the heterogeneous nucleation of bubbles, and this in turn controls the crystallization kinetics of microlite with the homogeneous nucleation of microlite and the diffusion-limited growth of crystal. The several orders of variation of microlite number density with the amount of decompression in laboratory experiments can be interpreted as the effect of the amount of decompression on the driving force for the diffusive bubble growth that controls the water exsolution rate.  相似文献   

Seismic site effects by an optimized 2D BE/FE method I. Theory, numerical optimization and application to topographical irregularities     

B. Gatmiri  C. Arson  K.V. Nguyen 《Soil Dynamics and Earthquake Engineering》2008,28(8):632-645

This paper deals with the evaluation of seismic site effects due to the local topographical and geotechnical characteristics. The amplification of surface motions is calculated by a numerical method combining finite elements in the near field and boundary elements in the far field (FEM/BEM). The numerical technique is improved by time truncation. In the first part of this article, the accuracy and the relevance of this optimized method are presented. Moreover, parametric studies are done on slopes, ridges and canyons to characterize topographical site effects. The second part deals with sedimentary valleys. The complexity of the combination of geometrical and sedimentary effects is underlined. Extensive parametrical studies are done to discriminate the topographical and geotechnical effects on seismic ground movement amplifications in two-dimensional irregular configurations. Characteristic coefficients are defined to predict the amplifications of horizontal displacements. The accuracy of this quantitative evaluation technique is tested and discussed.  相似文献