Plastic mechanism analysis of structural performances for stiffeners on bottom longitudinal web girders during a shoal grounding accident

A theoretical model is introduced in this paper for structural performance of stiffeners on double-bottom longitudinal girders in a shoal grounding accident. Major emphasis is placed on establishing the characteristic deformation mechanism of stiffeners and identifying major energy dissipation patterns. Numerical simulations using the LS-DYNA nonlinear finite-element program were carried out to examine thoroughly the progressive deformation process during sliding deformation. Stiffener deformations were observed to fall into two categories: stiffeners fully contacted with the indenter, and stiffeners subjected to indirect deformation due to energy transfer from attached girders. Grounding performance of stiffeners is substantially influenced by that of the attached plating, and therefore a review of the existing deformation models of longitudinal girders (i.e. Simonsen 1997, Midtun 2006 and Hong 2008) was included. Hong's model of bottom girders was found not capable of representing the effects of stiffeners, and a new model of girders was thus developed. Based on observation of the numerical deformation process and the new analytical girder model, a kinematically admissible model of stiffeners on bottom longitudinal girders was built. Using the methods of plastic mechanism analysis, simplified analytical expressions for energy dissipation by girder-attached stiffeners, both fully contacted and noncontacted, were formulated, and equations for grounding resistance were subsequently obtained. The theoretical expressions agree favorably with results from nonlinear finite-element simulations and capture two significant characteristics of the problem: that energy varies little with indentation for stiffeners that fully contacting the indenter, and that energy is independent of slope angle for indirectly deformed stiffeners. The proposed theoretical model helps to predict analytically shoal grounding performance of stiffeners on longitudinal girders with reasonable accuracy.     

搭铁异常分析及设计优化

由于电路搭铁连接异常,调节音响音量造成搭铁电阻动态变化,使得车门控制器工作电压变化导致车门异常打开的故障。     

有效预防荆江河段船舶搁浅事故的探讨

船舶搁浅是荆江河段主要事故险情之一。造成船舶搁浅既有水文、航道等客观方面的原因，更与船员素质、安全意识等密不可分。近年来，荆州海事局结合荆江河段特点采取了一系列强有力措施，成效显著。但要从根本上解决这些问题，必须从标准化、规范化入手，把创造良好通航环境与严格监管有机结合起来，从而达到有效预防预控的目的。     

RANS simulation of a container ship using a single-phase level-set method with overset grids and the prognosis for extension to a self-propulsion simulator

Steady flow simulations for the Korean Research Institute for Ships and Ocean Engineering (KRISO) container ship (KCS) were performed for towing and self-propulsion. The main focus in the present article is on the evaluation of computational fluid dynamics (CFD) as a tool for hull form design along with application of state-of-the-art technology in the flow simulations. Two Reynolds-averaged Navier-Stokes (RANS) equation solvers were employed, namely CFDShip-Iowa version 4 and Flowpack version 2004e, for the towing and self-propulsion cases, respectively. The new features of CFDShip-Iowa version 4 include a single-phase level-set method to model the free surface and an overset gridding capability to increase resolution in the flow and wave fields. The new features of Flowpack version 2004e are related to a self-propulsion scheme in which the RANS solver is coupled with a propeller performance program based on the infinitely bladed propeller theory. The present work is based on a close interaction between IIHR-Hydroscience and Engineering of the University of Iowa and Osaka Prefecture University. In the following article, overviews are given of the present numerical methods and results are presented and discussed for the KCS in towing and self-propulsion modes, including comparison with available experimental fluid dynamics (EFD) data. Additional evaluation is provided through discussion of the recent CFD Workshop Tokyo 2005, where both methods appeared to yield very promising results.     

青藏铁路格拉段防雷接地技术的研究

青藏铁路格拉段是世界上海拔最高的高原铁路，雷击过电压保护面临高原和冻土两大难题。针对雷击过电压的影响因素，在分析格拉段雷暴活动情况及沿线高原冻土地区地质特点的基础上，提出铁路沿线防雷接地工程的实施办法。结合高原冻土地区的特点，探讨了格拉段防雷接地技术的新思路和急需解决的问题。     

青藏铁路发电车DC600 V供电系统接地方式的比较

对比了青藏铁路发电车DC600 V供电系统的2种接地方式,最终确定了零线对地绝缘接地方式。     

整车线束设计及搭铁策略分析

在整车线束设计中，很大一部分工作是在验证熔断器与线型选择是否合理、线束布置是否得当以及搭铁点的选择是否可靠。本文通过实例介绍整车线束设计中的一些基本方法。     

氢氧非平衡等离子体法直接合成过氧化氢

在常温常压下,利用介质阻挡放电反应器,通过氢气和氧气的气相等离子体反应直接合成出过氧化氢.考察了反应器结构对过氧化氢合成的影响.结果表明.反应器结构是过氧化氢合成的重要影响参数.在优化条件下,用氢氧等离子体气相反应可获得54%的过氧化氢收率和61%的过氧化氢选择性.     

无碴轨道综合接地系统方案的探讨

随着无碴轨道在客运专线上的大量采用，钢轨对大地的漏泄电阻值将会有较大提高，为防止钢轨电位急剧升高引起人身设备安全问题，相关专业应加强综合接地系统工程的探讨研究。     

船舶搁浅的模糊概率计算

目前，计算船舶搁浅的概率时常采用故障树和事件树方法，以确定的概率数表示底事件的发生概率，这种方法的一个不利之处在于无法考虑基本事件发生概率的不确定性，所以无法了解船舶搁浅概率的不确定性，本文引入了合适的模糊数表示基本事件的发生概率，通过模糊计算算法得到了船舶搁浅的模糊概率，并进行了敏感分析，确定了减小船舶搁浅事故发生的措施，与其他方法的计算结果比较表明，本文采用的方法更有利于了解船舶搁浅的概率分布规律。