Impact Buckling and Post-Buckling of Elasto-Viscoplastic Cylindrical Shell Under Torsion

The dynamic torsional buckling and post-buckling of elasto-plastic circular cylindrical shell isstudied.By the usage of the Bodner-Partom constitutive relation,the present visco-plastic problem is treat-ed as an orthotropic elastic problem.Based on the nonlinear large deflection shell therory,the governingdynamic buckling equation is solved by the Runge-Kutta method,and the critical buckling stress is deter-mined by the B-R criterion.The present paper is mainly focused on the imperfection sensitivity,the strainrate sensitivity,and the dynamic post-buckling characters for the shell loaded dynamically with a constantshear strain rate.Numerical results show that the critical shear stress and imperfection sensitivity will in-crease with the increase of strain rate.It is found that the elastic buckling stress is more sensitive toimperfection than the visco-plastic buckling.The present research also reveals some dynamic post-bucklingcharacters for the cylindrical shell,and it is shown that the shell will vibra     

加入WTO对中国旅游业的影响及应对措施

加入WTO必然对中国旅游业的发展产生重大影响，既包括创造机遇，也包括提出挑战。对此，应采取加快体制改革、留住高素质的旅游经营管理与服务人才、积极学习和借鉴国际旅游业先进的经营管理模式和经验、适时调整旅游业的产业对策，宣传中华民族文化、抓住奥运旅游的机遇，创造中国旅游的新品牌等应对措施，使得中国旅游业步入按国际惯例办事的轨道。     

开发胶东温泉地热水对环境的影响

根据地热水中阴离子的组分与温泉水类型，指出其中Ⅱ＿１、Ⅱ＿２：型水温高，日采水量大，矿化度高，水质复杂，相应的环境效应明显．提出地热水的大规模开采以及尾水的大量排放，对温泉周边的生态环境、工程环境、土壤及地下水等方面有明显的影响．     

Abundance of the introduced seastar, Asterias amurensis, and spatial variability in soft sediment assemblages in SE Tasmania: Clear correlations but complex interpretation

The northern Pacific seastar, Asterias amurensis, was first collected in southeast Tasmania in 1986. Mistaken for the endemic asteroid Uniophora granifera, its true identity was not realised until 1992. It is now a conspicuous predator in soft sediment habitats in this region, and is considered a major threat to native assemblages and commercial species. We examined the structure of soft sediment assemblages at different spatial scales in southeast Tasmania, and correlated spatial variation in community composition with seastar abundances. We found that the structure of soft sediment assemblages is highly variable at a range of spatial scales from metres to tens of kilometres. Clear differences in the composition of assemblages and abundances of major taxa were detected between areas with and without seastars and between areas with low and high seastar densities. However, the nature of these patterns suggests that they are more likely due to differences in sediment characteristics than due to impacts of the seastar. Thus, spatial differences in soft sediment assemblages might have been erroneously attributed to seastars without detailed information on important physical factors such as sediment characteristics. A second survey, using larger sampling units (1 m²) but across a more limited spatial extent, targeted bivalves and heart urchins that were identified as important prey of the seastar in observations of feeding and in experimental studies. Large-scale patterns of abundance and size structure were consistent with seastar effects anticipated from small-scale experimental and feeding studies for some, but not all, species. While the field survey ultimately provided evidence about the presence or absence of seastar impacts at large-scales, the identification of key ecological variables in experimental and feeding studies proved crucial to both the design and interpretation of patterns observed in the large-scale surveys. Overall, this work highlighted the necessity to consider multiple lines of evidence rather than relying on a single ‘inferential’ test, in the absence of pre-impact data.     

南四湖湖内浅槽工程施工对水环境的影响及控制措施

南四湖湖内工程是沂沭泗河洪水东调南下续建工程的单项工程,工程区位于山东省省级自然保护区内;挖泥船施工将对湖内水环境产生一定影响。本文从排泥场回水污染物、生产废水和生活污水三个方面阐述了工程施工对水环境的影响程度,并且提出了相应的控制措施。     

胶州湾泛亚码头疏浚方案优选及悬浮物影响预测

采用有限元分步杂交方法,在已建潮流场的基础上,建立了胶州湾疏浚物悬浮泥沙的二维输运-扩散模型,并应用于胶州湾前湾港区泛亚码头工程疏浚区的疏浚物输运扩散的数值模拟预测。根据预测结果分析了泛亚码头疏浚区施工期间悬浮泥沙对附近海域水环境和生态环境的影响,并对不同的疏浚方案进行了优选。