Static Analysis of Collision Strength of Offshore Platform     

Li Runpei Chen Weigang Gu Yongning Professor  Shanghai Jiao Tong University  Shanghai Assistant  Shanghai Jiao Tong University  Shanghai 《中国海洋工程》1996,(1)

In this paper a numerical analysis method combining FEM incemental technique with limit analysis concept is proposed for the study of the static strength of offshore platform in collision. Large deformation and plasticity are accounted for and the limit yield surface expressed by generalized stress for a tubular section is derived. The modified stiffness matrix of space beam element is formulated by Plastic Node Method. The buckling behavior of beam columns can also be taken into account. It can trace the generation of plastic hinges during loading and finally the ultimate strength of offshore platform against collision is obtained.  相似文献   

煤层气开采对环境的影响   总被引：3，自引：0，他引：3  

严群  ;王庆伟  ;李金海 《中国煤炭地质》2008,(12):57-59

煤层气是一种廉价、洁净、高效的新型能源,其开发利用可以弥补常规天然气和燃油的不足,750m^3煤层气可顶替1t标准煤。煤层气开发对环境的影响主要是减少了煤矿甲烷气体的排放,降低温室效应。其负面影响是在钻探、压裂、回注水和提纯过程中会造成煤层和煤层气中杂质气体和有毒有害物质富集,对大气和地下水造成污染。  相似文献   

Global climatic change – the latest scientific understanding     

Bruce A. Callander 《GeoJournal》1997,42(1):55-63

IPCCs statement in its 1995 report (IPCC 1996) that a human influence was discernible in global climate has been widely quoted but often misunderstood. The character of the evidence underpinning this detection statement is explained so that its strengths and weaknesses can be better understood and the subtleties of its message better appreciated. To demonstrate the close linkage between the government-approved summary and the underlying chapters of the IPCC report the detailed evolution of the detection statement from first draft through to the form finally approved by the IPCC is described.  相似文献   

非加温型四连栋塑料温室内外温湿度关系研究   总被引：7，自引：1，他引：7  

李军  杨秋珍  吴元中 《气象》2005,31(8):22-24

根据1999年12月～2002年8月典型天气（晴天、多云、阴天）下非加温型四连栋塑料温室中间1．5m高度气温、相对湿度的观测数据，应用逐步回归分析方法建立了冬季、春秋季、夏季典型天气下温室内日平均气温、日最高气温、日最低气温、日平均相对湿度与气象站气象要素间的关系式，为温室蔬菜品种筛选、蔬菜标准化栽培、无公害蔬菜生产和病虫害防治提供小气候方面的技术数据。  相似文献   

Analyzing CO2 emissions mitigation by technology improvement in Central and Eastern Europe     

Diana Ürge-Vorsatz  Adam Szeszler 《GeoJournal》2002,57(3):211-226

As a legacy of the centrally planned economy, the economies in transition of Central and Eastern Europe (CEE) have a unique potential to reduce their greenhouse gas emissions through the improvement in their high energy intensities. Since much of this `low-hanging fruit' in energy-efficiency improvements can be highly cost-effective, many developed countries facing difficulties in meeting their greenhouse gas (GHG) emission targets domestically are eager to find such opportunities in the CEE region. Therefore, studies analysing the potentials and costs of carbon dioxide reduction through technology improvement in the region have come into the limelight. While there are a few excellent studies in the region aimed at analysing climate change abatement potentials, they all embark on different assumptions, methodologies and boundary conditions. It is hence difficult, if not impossible, to compare and analyse the results of these studies across different authors, countries or time horizons. Consequently, the purpose of this paper is to place four leading studies on GHG mitigation through technology improvement from the CEE region into an internationally comparable framework. Four studies were selected from three countries, Poland, Hungary and Estonia, which are all the results of major national and international efforts to assess costs and potentials of GHG reduction. The paper places their assumptions, methods and final results into a framework which enables policy-makers and project designers to compare these across geographical and technological boundaries. Since other studies from around the globe have been analysed in this framework in the literature, this paper provides a vehicle for the findings of these four studies to be compared to others worldwide. In addition, the paper highlights a few areas where similar studies to be completed in the future in the region may be enhanced by incorporating features used in GHG mitigation research in other parts of the world. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

上覆岩层组合运动的力学解析特征研究   总被引：2，自引：0，他引：2  

刘开云  乔春生  滕文彦 《工程地质学报》2003,11(4):372-377

运用弹性薄板理论和复合材料力学的层合板理论,讨论了在覆岩运动中起决定作用的组合关键层的应力,为计算组合关键层的整体强度提供了途径;并且从控制开采沉陷工程实际入手,将结构塑性极限分析理论运用于组合关键层的失稳最大荷载计算,解析得出了充分采动情况下关键层塑性极限荷载的表达式,从另一个角度得到了一种判别关键层位置的新方法,为实施离层带注浆减沉提供参考。  相似文献   

全球增暖的另一可能原因初探   总被引：14，自引：1，他引：14       下载免费PDF全文

李崇银  翁衡毅  高晓清  钟敏 《大气科学》2003,27(5):789-797

太阳是地球流体(大气和海洋等)运动的最终能量源,地球环境,尤其是气候的变化不能不与太阳活动有关.目前,普遍将全球增暖归结为温室气体含量增加所导致的温室效应的加剧,这无疑是有一定依据和有道理的.但从科学上来讲,人类活动所引起温室气体增加的影响,并非是唯一原因.基于已有的一些研究结果,从太阳活动的观点所进行的初步分析表明,太阳活动也可能是引起近世纪全球增暖的另一个重要原因.太阳活动的影响主要包括太阳辐射的直接影响和引发地磁场变化的间接影响两个方面,地球磁场的变化将可通过动力过程和热力过程而影响大气环流和气候的变化.  相似文献   

内蒙古草原温室气体排放日变化规律研究   总被引：11，自引：0，他引：11  

胡玉琼  王跃思  纪宝明  王明星  杜睿 《南京气象学院学报》2003,26(1):29-37

采用静态值－气相色谱法研究内蒙古草原温室气体N2O、CO2、CH4与大气交换的日变化规律。CO2日排放变化形式基本相同，和大气交换的总结果是向大气排放，影响草原N2O排放日变化形式的关键是土壤含水量和表层土壤理化特性，日温变化主要影响其日变化强度；影响草原CH4日变化形式的关键因子是土壤水分和供氧状况，而温度和植物的生长状况则影响吸收强度，利用内蒙古草原温室气候排放相对固定的日变化形式，可以对相同生产季内每周1次的观测结果进行矫正。  相似文献   

日光温室低温寡照灾害指标   总被引：27，自引：4，他引：27       下载免费PDF全文

魏瑞江 《气象科技》2003,31(1):50-53

文章根据1965～2000年河北省日光温室试验观测资料及各地历年低温寡照对蔬菜的影响程度，确定了低温寡照灾害等级指标，分析了低温寡照的时空分布规律，20世纪80年代以后，河北省各市低温寡照发生次数比60、70年代明显增多；随着纬度增高，河北省低温寡照发生次数明显减少，危害程度明显减轻。  相似文献   

慢地震慢前兆的机制研究   总被引：12，自引：1，他引：12  

许昭永  杨润海  胡毅力  许峻  王赟赟 《地震》2003,23(2):12-20

通过岩石高温高压破裂实验与有机玻璃破裂试验的应力—应变曲线对比、地震波形记录(观测资料)与试样破裂波形(实验资料)对比、地震前后定点应变与主破裂前后应变形态变化的对比，认为慢地震是临界或亚临界破裂或预先滑动所致，是低频应变波动。它是材料屈服、弱化或塑性变化的必然结果。而慢前兆则是临近大地震(大破裂)前出现的诸如形变、低频地震波(破裂弹性波)等的短期及临震前兆现象，它比较可靠。但由于许多岩石主破裂前并无明显的临界破裂或预滑动现象，也并非所有岩石都一定出现明显屈服，所以也并非每个地震前都有慢地震，因此，也就不一定都出现低频波动。从而，也并不一定都出现相同的短期、临震前兆现象。  相似文献