提高水上沉桩正位率的几点认识

通过调查分析,找出影响水上沉桩偏位的因素:地质地貌、水文气象、船机设备、水下障碍物、人员责任心和经验、测绘仪器的误差、过往船只,等等。针对其中影响桩跑位和桩倾斜的主要原因,即:1)起帽后桩倒伏大;2)桩架不垂直;3)碎石层上沉桩;4)挖泥泥面起伏大,总结出一套控制水上沉桩偏位行之有效的方法。     

原油流量计系数的使用及超差量的处理

流量计具有计量精度高、便于在线检定、容易实现自动化等优点,其作为原油计量交接的主要器具已经得到广泛应用.但在应用过程中,还存在许多需要改进和规范的方面.研究的目的是促进原油计量站更多地使用流量计系数方法,使计量交接更准确;规范流量计出现超差时超差量的处理办法.根据多年来在流量计使用方面的经验,通过总结分析、图表描述和实...     

浅埋黄土隧道土石分界高度对初期支护结构安全性的影响分析

为获得浅埋黄土隧道土石分界高度对初期支护结构安全性的影响,文章以临县隧道为工程背景,采用数值模拟的方法研究了浅埋土石分界高度及土石分界面位置对隧道初期支护结构安全性的影响。结果表明:土石分界致使隧道初期支护结构安全系数发生突变,分界面倾斜时安全系数分布不对称。同一种埋深条件下,随着土石分界面位置的下移,土石分界面以上部分偏压减弱,分界面以下的部分偏压增强。同一界面深度条件下,隧道初期支护结构左右断面偏压情况随着埋深增加而增大。当土石分界面分别位于隧道上导坑和中下导坑、分界面倾角为10°时,可通过增加20%隧道左侧荷载或减小20%右侧抗力系数来进行荷载计算。     

船舶回转性能分析

在对船舶作回转性能分析时，采用战术直径表征其他回转特征量，计算出不同舵角、航速、纵倾及排水体积下的回转圈战术直径。衡量各因素对战术直径的影响程度，总结战术直径随各因素变化的规律，得到不同排水量之间战术直径的简化算法，为试航回转试验的特征量从设计吃水转化为满载吃水提供了一种较简捷的近似换算方法。     

试析母语思维影响下的大学英语写作教学

本文着重分析影响大学英语写作的两个主要因素——母语思维与文化冲突,并结合多种教学方法展开论述,总结出相对应的学习方法.研究表明这些学习方法在培养学生写作能力方面有显著成效,促使学生养成良好的英语思维习惯,具备较强的自主学习能力.     

有限元分析在船舶轴系设计中的应用

使用Abaqus软件建立船舶轴系中间轴的模型，通过有限元方法计算轴法兰过渡处的应力集中系数，分析应力集中系数与轴系扭振计算结果之间的关系。相比于单圆弧过渡，三段式圆弧过渡将应力集中系数减小了20%，持续运转扭振许用应力提高了38%，瞬时运转扭振许用应力提高了17%。运用有限元分析方法检验校核了船舶轴系设计的合理性。     

索赔风险的模糊综合与辨识模型的应用

对工程各涉及方来讲,索赔风险的发现与识别既是索赔管理的首要任务,也是一个难点问题。运用索赔风险的模糊综合与辨识模型分析索赔风险,可以迅速而准确地解决这一难题。     

Fatigue damage induced by vortex-induced vibrations in oscillatory flow

Vortex-induced vibration (VIV) of a flexible cylinder in oscillatory flow was experimentally investigated in an ocean basin. An intermittent VIV was confirmed to have occurred during the tests. The fatigue damage caused by VIV was calculated based on rainflow counting and a standard S–N curve. There are 3 main observations for fatigue damage from VIV in oscillatory flow: 1) the damage varied significantly with the KC number, which is a unique feature for VIV in oscillatory flow. 2) Fatigue damage at small KC number cases was found to be larger compared to those at large KC numbers owing to the fact that number of vortex shedding cycles per half of the motion cycle is low, and damping within half of the motion cycle will hence become low. The fact that vortices from the previous cycle still are active during the next may also contribute to the large response at small KC numbers. 3) ‘Amplitude modulation’ and ‘mode transition’, two specific features for VIV in oscillatory flow, were found to have a strong influence on fatigue. Fatigue damage has also been calculated by an empirical VIV prediction model assuming that all cases have steady flow at an equivalent velocity. Finally, a simplified method for calculating fatigue damage from VIV in oscillatory flow based on steady flow conditions is proposed. A modification factor diagram is presented, but the scope of the present study is too limited to provide a good basis for a general model for this factor. A general model for how to apply results from constant current analysis to predict fatigue in oscillatory flow will therefore need further research.