Technical reliability of the Greek coastal passenger fleet     

《Marine Policy》2005,29(1):85-92

Ship reliability is a vital component of quality in passenger shipping, since serious shipboard equipment failures hinder ship seaworthiness and inevitably lead to delays with apparent detrimental effects upon the “value-of-time” and “just-in-time” properties of this transportation system. Throughout the history of modern Greece, the Greek coastal passenger system constituted the most vital mode of transport for the national economy and integrity. Furthermore, at a time such as the forthcoming 2004 Summer Olympics, Greek coastal passenger shipping will be called upon to play a major role in the success of the Games and in the promotion of the international image of the host country.The present work focuses on the reliability of the Greek coastal passenger fleet, through reference to a period of transition (1996–2002) and lines (Piraeus, Rafina, Lavrio) of acknowledged significance. In this respect, it attempts to capture the influence of various factors upon the reliability of the fleet, through the presentation and analysis of data and results relevant to reported shipboard equipment failures, fleet characteristics and transport work performed.The results generally reveal a steady trend of fleet reliability improvement, amidst a continually increasing transport demand. However, the influence of the observed fleet renewal and certain network characteristics allow for further improvement through the implementation of appropriate policy measures.  相似文献   

Second-Order Potentials and Forces for Two-Dimensional Diffraction Problem of Finite Water Depth     

Duan Wenyang  He Wuzhou Graduate student 《中国海洋工程》1994,(3)

-In this paper, an analytical solution in the outer region of finite water depth is derived for the second-order diffraction potential, which gives a clear physical meaning of the wave transmission and reflection characteristics in the far field. A numerical method-simple Green's function technique-for calculating the second-order diffraction potential in the inner region is also described. Numerical results are provided for the second-order wave forces on a semi-submerged cylinder. It is found that the contribution of second-order diffraction potential to second-order wave forces is important. The effect of water depth and submerged depth on the wave force is also discussed.  相似文献   

组合基础隔震在建筑工程中的应用   总被引：2，自引：1，他引：2  

魏陆顺  周福霖  刘文光 《地震工程与工程振动》2007,27(2):158-163

隔震作为一种新的抗震技术,已广泛应用于新建和加固的建筑工程,同时,许多新型式的支座得到了开发和应用。组合基础隔震是一种新的隔震设计思想,能充分应用不同类型隔震支座的特性,有效降低上部结构地震反应。本文介绍了组合基础隔震在某一工程中的应用,工程中使用的支座包括普通橡胶隔震支座、铅芯橡胶隔震支座和弹性滑板支座三种类型,对全部使用支座进行了常规检测,结构计算采用等效线性法、能量包络法和时程反应分析等方法,计算结果表明:组合基础隔震能有效降低上部结构的反应,隔震层的变形控制在安全范围之内。  相似文献   

时间推移地震反演的连续模型与算法   总被引：5，自引：2，他引：5       下载免费PDF全文

陈勇  韩波 《地球物理学报》2006,49(4):1164-1168

针对时间推移地震反演问题建立了依赖勘探时间的数学模型，并在此基础上设计了全局收敛的连续型及逐次递归算法.将同伦方法与Tikhonov正则化方法相结合，设计了初次勘探反演的同伦-正则化方法.以三维时间推移地震为例，在连续型及逐次递归算法的基础上构造了快速的局域化反演算法.数值模拟结果说明了上述方法都是有效的.  相似文献   

浅埋圆柱形弹性夹杂附近等腰三角形凸起地形引起的SH波的散射   总被引：4，自引：0，他引：4  

刘刚  刘殿魁  杜永军  陈海涛 《地震工程与工程振动》2006,26(4):1-8

文章利用“契合”思想,给出了地下弹性夹杂与地面上的等腰三角形凸起地形引起的SH波散射问题的解析解答。利用复平面下坐标移动,通过区域Ⅰ和区域Ⅱ以及区域Ⅱ和区域Ⅲ的“公共边界”位移应力连续条件,建立起求解该问题的无穷代数方程组并截断有限项进行求解,最后通过具体算例及结果分析得出相应结论。  相似文献   

关于防震减灾信息和辅助决策系统的安全性问题     

金波  陶夏新  高光伊 《世界地震工程》2006,22(1):27-31

根据防震减灾信息和辅助决策系统安全性的特点,具体分析了保证系统安全性的步骤和方法,并结合某分布式防震减灾信息和辅助决策系统框架,对其进行了安全性分析和安全性规划,制定了相应的安全性策略和措施,并介绍了可以进行安全性认证的国家权威机构,最后指出了防震减灾系统发展的趋势和存在的隐忧。  相似文献   

Rupture directivity and hanging wall effect in near field strong ground motion simulation   总被引：1，自引：0，他引：1  

陶夏新  王国新 《地震学报(英文版)》2003,16(2):205-212

A random synthesis procedure based on finite fault model is adopted for near field strong ground motion simulation in this paper.The fault plane of the source is divided into a number of sub-sources,the whole moment magnitude is also divided into more sub-events.The Fourier spectrum of ground motion caused by a sub-event in given sub-source,then can be derived by means of taking the point source spectrum,attenuation with distance,energy dissipation,and near surface effect,into account.A time history is synthesized from this amplitude spectrum and a random phase spectrum,and being combined with an envelope function.The ground motion is worked out by superposition of all time histories from each sub-event in each sub-source,with time lags determining by the differences between the triggering times of sub-events and ddistances of the sub-sources.From the example of simulations at 21 near field points in a scenario earthquake with 4 dip angles of the fault plane,it is illustrated that the procedure can describe the rupture directivity and hanging wall effect very well.To validate the procedure,the response spectra and time histories recorded at three near fault stations MCN,LV3 and PCD during the Northridge earthquake in 1994,are compared with the simulated ones.  相似文献   

THE PRELIMINARY STUDY ON THE PRECIPITATION CHEMISTRY AT THE CHINESE GREAT WALL STATION, ANTARCTICA IN 1998^*          下载免费PDF全文

TANG Jie  YU Xiaolan  SHI Yufeng  CHENG Hongbing  WANG Guogui 《Acta Meteorologica Sinica》2003,17(3):364-375

This paper reports the analysis results (including pH,conductivity and ion concentrations) of the precipitation samples collected at the Chinese Great Wall Station,Antarctica (62°13'S, 58°58'W,ASL10.0 m) in 1998.The average pH value and conductivity were 5.62 and 85.16 μS/cm,respectively.The pH value and conductivity of precipitation were higher during autumn, but lower during other seasons.The major ions in the precipitation were Cl^- and Na⁺,followed by SO₄^2-,Mg²⁺,Ca²⁺,K⁺,NO₃^-,NH₄⁺ with the lower concentrations in order.The positive correlation significantly existing between the major ions,except NO₃^- and NH₄⁺,indicated that those major ions might come from same sources.The fact that the relative abundances of ions in precipitation were very close to that of seawater of Antarctic Ocean indicated that marine aerosol was the dominant source of the ions of precipitation.However,there were yet other sources which may contribute to Ca²⁺ ion in the precipitation.The precipitation at the area was characterized by marine type chemically.  相似文献   

Relationship between earthquake and volcanic eruption inferred from historical records     

陈洪洲  高峰  吴雪娟  孟宪森 《地震学报(英文版)》2004,17(4):500-506

Introduction From the records of Wudalianchi volcanic group eruption in 1720~1721 obtained from the Man ethnic group files of Heilongjiang General Yamen in Qing Dynasty (WU, 1998; CHEN, WU, 2003), we have discovered the eruption time, state, material and scale of Laoheishan and Hu-oshaoshan volcanoes, as well as numerous seismic records. These historical materials are discov-ered for the first time although the study on Wudalianchi volcanic group has a long history. These earthquakes co…  相似文献   

从历史记录看地震与火山喷发关系   总被引：2，自引：1，他引：2       下载免费PDF全文

陈洪洲  高峰  吴雪娟  孟宪森 《地震学报》2004,26(4):448-453

史料记载表明，五大连池火山1720~1721年喷发期间有大量地震活动.本文从描述这些地震活动的文字记录入手，并结合国际火山地震研究的新成果，探讨了地震类型及地震与火山喷发关系，指出震群是火山喷发的重要前兆指标，强调火山地震的监测对火山喷发预报的意义.   相似文献