运用灾害熵浅析沙尘暴强度   总被引：5，自引：3，他引：5  

李向军  陈亚宁  欧阳辉 《干旱区地理》2002,25(4):350-353

以信息熵原理为基础，引入灾害熵概念，评价自然灾害的发生的不确定性和根据各致灾因子的强弱，确定灾害事件的重要性因子，构建灾害信息量计算模型。并以新疆境内达坂城、精河、哈密、吐鲁番、鄯善等五个地区的多年沙尘暴灾害统计数据为研究实例，计算分析了灾害次数、灾害熵。经过分析得出：哈密地区的沙尘暴灾害不仅灾害强度最烈，致灾因子亦最为活跃。通过应用灾害熵及其相应的修正模式，可以定量的确定灾害的影响强度，定性地说明致灾因子的多寡。  相似文献   

Chlorinated pesticides in mussels from Guanabara Bay, Rio de Janeiro, Brazil     

Xavier de Brito AP  De Andrade Brüning IM  Moreira I 《Marine pollution bulletin》2002,44(1):79-81

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Late Maastrichtian litho- and ecocycles from hemipelagic deposits of eastern Sinai, Egypt     

Sebastian Lüning  Akmal M. Marzouk  Jochen Kuss 《Journal of African Earth Sciences》1998,27(3-4)

A biostratigraphical and palaeoecological survey employing calcareous nannofossils and planktonic and benthonic foraminifera has been carried out in four sections of hemipelagic marls and chalks of the Late Maastrichtian Abathomphalus mayaroensis Zone of eastern Sinai, in order to evaluate the mechanisms controlling the composition of the well preserved microfauna and nannoflora.The Abathomphalus mayaroensis Zone in eastern Sinai can be easily identified by the wide occurrence of the index fossil A. mayaroensis and can be further subdivided by the first occurrences of Plummerita reicheli (ex. P. hantkeninoides) and Micula prinsii. Microfossil abundances and lithologies are characterised by pronounced repetitive distribution patterns. These include low and high frequency fluctuations of the planktonic/benthonic (P/B) foraminiferal ratio, repetitive changes in the abundance of calcareous nannofossils and benthonic foraminifera, as well as the development of chalk-marl couplets and thinning upward chalk packets. both microfossil distribution patterns and the occurrence of rhythmites are attributed to changes in primary palaeoproductivity. Semiquantitative investigations of calcareous nannofossils and a few selected benthonic foraminifera yield evidence of the presence of high (HP) and low (LP) productivity assemblages.The interpreted HP assemblage is dominated by Glaukolithus diplogrammus, Manvitella pemmatoidea, Microrhabdulus decoratus and Micula murus and the benthonic foraminifera Neoflabellina jarvisi; the LP assemblage is characterised by Lithraphidites quadratus and Bolivinoides draco. However, further quantitative studies are necessary to reconstruct the exact composition of these assemblages and to explain deviatory developments. The chalk-marl couplets, thinning-upward chalk packets and the high frequency P/B patterns are interpreted to reflect productivity changes related to orbital forcing. These hemipelagites were deposited during the latest phase of the southern Tethyan upwelling system, which was active from the Santonian to the Late Maastrichtian with a peak in the Campanian. Termination of upwelling just before the K/T boundary also provides a good explanation for the change towards a palaeobathymetric control on foraminiferal distribution, as observed for the Palaeocene of central east Sinai.  相似文献   

浮式生产储油船船体疲劳计算   总被引：2，自引：0，他引：2  

刘建成  马廷德等 《海洋工程》2001,19(2):50-55

船体结构的疲劳问题一直是船舶设计者十分关注的问题，特别是高强度钢在船体结构中的广泛使用，使船体结构的疲劳破坏问题更加突出。本文以一大型浮式生产储油船（Floating Production and Storage and Offilading)为例，系统地介绍了一种基于S－N曲线和Miner线性疲劳累积损伤原理，计算船体在局部结构应力热点处的疲劳寿命。该方法考察了船舶运营期内的实际工况和海况条件，船体局部应力热点的焊接情况，几何形状，受载形式以及尺寸效应等因素。计算中借助了DNV船级社的SESAM程序系统的部分模块。  相似文献   

大亚湾拟菱形藻水华及其在生物群落中的生态地位   总被引：5，自引：1，他引：5  

陈菊芳  齐雨藻  徐宁  江天久  吕颂辉 《海洋学报》2005,27(1):114-119

对2000年4~5月藻类水华高发期大亚湾澳头海域的拟菱形藻进行逐日调查,并对其与浮游植物、浮游动物的相关关系进行分析.调查初期,整个生物群落的种类组成数量都相对贫乏;拟菱形藻数量急剧增长,最高的测站密度可达2.93×106个/dm3.拟菱形藻水华的组成种类有拟极细拟菱形藻和尖刺拟菱形藻两种,以尖刺拟菱形藻稍占优势.水华形成中其他种类硅藻和甲藻在种类组成和数量上也有一定程度的增加.分析表明,拟菱形藻在浮游植物群落的种间竞争中具有优势,并成为春季硅藻水华的最重要的组成者.桡足类等浮游动物对拟菱形藻的下行控制并不能明显抑制拟菱形藻的增长及水华的产生,这与其偏爱以其他种类藻类为食有关.以上因素外加拟菱形藻对环境的广泛适应性促使其在该水域成为最常见的赤潮生物之一.  相似文献   

历书激光排版系统     

何玉囡  姚海燕 《紫金山天文台台刊》2000,19(1):47-55

历书激光排版系统研究主要用于《中国天文年历》、《天文测量简历》、《航海天文年历》、《天文普及年历》及各种民用历书计算,编辑,排版和绘图自动化,使出版社可以直接采用激光印字机打印出的书稿照相制版或用记录在软盘上的排版文件直接在照相机上安排。  相似文献   

环境航空测量与评价系统的设计与实现     

韦中亚  邬伦  徐素宁 《地理与地理信息科学》2000,16(4):86-89

基于航空测量、GIS与GPS技术的环境航空测量与评价系统是大面积环境测量与评价的高效、快速、精确的方法。本文介绍环境航空测量与评价系统的软、硬件组成 ,系统功能设计及实现。对国家资源环境数据库的完善 ,对于数字地球、数字中国的建设 ,有一定的现实意义。  相似文献   

硼酸/硼砂与多羟基化合物在水溶液中的反应:pH、电导率、Raman光谱研究          下载免费PDF全文

柏春  刘海宁  刘忠  叶秀深  张慧芳  李军  吴志坚 《盐湖研究》2020,28(2):56-64

与多羟基化合物络合是去除和分离溶液中微量硼的有效手段,但我们对多羟基化合物与硼酸盐的反应缺乏深入认识。本文通过测定硼酸/硼砂与木糖醇、D-果糖、D-山梨醇和D-甘露醇在水溶液中反应的pH、电导率及Raman光谱,综合对比研究了硼酸/硼砂与四种多羟基化合物的络合反应。对于多羟基化合物/硼酸水溶液,随着多羟基化合物浓度的增加,溶液的pH值降低,电导率显著增加。对于多羟基化合物/硼砂水溶液,随着多羟基化合物浓度的增加,溶液的pH值和电导率都是首先明显降低,之后缓慢降低。为使硼酸/硼砂络合完全,多羟基化合物与硼酸的物质量的比要大于2。四种多羟基化合物与硼酸反应后,都出现了新的Raman峰,D-甘露醇与硼酸在溶液中反应后,在1 207 cm~(-1)处出现了较强的Raman峰。在四种多羟基化合物中,D-甘露醇与硼酸/硼砂的反应效果更好。  相似文献   

Coordinated Ocean-ice Reference Experiments (COREs)     

Stephen M. Griffies  Arne Biastoch  Claus Böning  Frank Bryan  Gokhan Danabasoglu  Eric P. Chassignet  Matthew H. England  Rüdiger Gerdes  Helmuth Haak  Robert W. Hallberg  Wilco Hazeleger  Johann Jungclaus  William G. Large  Gurvan Madec  Anna Pirani  Bonita L. Samuels  Markus Scheinert  Alex Sen Gupta  Camiel A. Severijns  Harper L. Simmons  Jianjun Yin 《Ocean Modelling》2009,26(1-2):1-46

Coordinated Ocean-ice Reference Experiments (COREs) are presented as a tool to explore the behaviour of global ocean-ice models under forcing from a common atmospheric dataset. We highlight issues arising when designing coupled global ocean and sea ice experiments, such as difficulties formulating a consistent forcing methodology and experimental protocol. Particular focus is given to the hydrological forcing, the details of which are key to realizing simulations with stable meridional overturning circulations.The atmospheric forcing from [Large, W., Yeager, S., 2004. Diurnal to decadal global forcing for ocean and sea-ice models: the data sets and flux climatologies. NCAR Technical Note: NCAR/TN-460+STR. CGD Division of the National Center for Atmospheric Research] was developed for coupled-ocean and sea ice models. We found it to be suitable for our purposes, even though its evaluation originally focussed more on the ocean than on the sea-ice. Simulations with this atmospheric forcing are presented from seven global ocean-ice models using the CORE-I design (repeating annual cycle of atmospheric forcing for 500 years). These simulations test the hypothesis that global ocean-ice models run under the same atmospheric state produce qualitatively similar simulations. The validity of this hypothesis is shown to depend on the chosen diagnostic. The CORE simulations provide feedback to the fidelity of the atmospheric forcing and model configuration, with identification of biases promoting avenues for forcing dataset and/or model development.  相似文献   

Improvements in turbulence model realizability for enhanced stability of ocean forecast and its importance for downstream components     

Brüning  Thorger 《Ocean Dynamics》2020,70(5):693-700

Ocean Dynamics - The numerical stability of ocean circulation models is of high significance in operational forecasting. A substantial improvement in numerical stability of the 3D-ocean model HBM...  相似文献