Fatigue damage estimation in non-linear systems using a combination of Monte Carlo simulation and the First Order Reliability Method

For non-linear systems the estimation of fatigue damage under stochastic loadings can be rather time-consuming. Usually Monte Carlo simulation (MCS) is applied, but the coefficient-of-variation (COV) can be large if only a small set of simulations can be done due to otherwise excessive CPU time. The reason is that the fatigue damage estimation is very sensitive to the largest values from the simulations. The paper suggests the additional use of the First Order Reliability Method (FORM) to get a better estimation of the tail in the distribution of the estimated fatigue damage and thereby reducing the COV. For a specific example dealing with stresses in a tendon in a tension leg platform the COV is thereby reduced by a factor of three.     

Analysis of structural crashworthiness of double-hull ships in collision and grounding

A conceptual design framework for collision and grounding analysis is proposed to evaluate the crashworthiness of double-hull structures. This work attempts to simplify the input parameters needed for the analysis, which can be considered as a step towards a design-oriented procedure against collision and grounding. Four typical collision and grounding scenarios are considered: (1) side structure struck by a bulbous bow, (2) side structure struck by a straight bow, (3) bottom raking, (4) bottom stranding. The analyses of these scenarios are based on statistical data of striking ship dimensions, velocities, collision angles and locations, as well as seabed shapes and sizes, grounding depth and location. The evaluation of the damage extent considers the 50- and 90-percentile values from the statistics of collision and grounding accidents. The external dynamics and internal mechanics are combined to analyse systematically the ship structural damage and energy absorption under accidental loadings.     

移动式损管训练舱堵漏水循环系统设计

文章通过3ds Max和AutoCAD软件设计出移动式损管训练舱堵漏水循环系统,在系统中完善了堵漏训练所需的配套设施,解决堵漏水的循环利用,使损管堵漏训练能满足海警官兵日常训练要求.     

水泥混凝土路面的病害防止与维修

分析水泥混凝土路面的病害,针对各种病害,提出维修方法。     

A STUDY ON LIMITATION OF HIGH-ENERGY SHOCK WAVE-INDUCED RENAL DAMAGE BY SALVIA MILTIORRHIZAE INJECTION IN RABBIT MODEL

Extracorpealshockwavelithotripsy (ESWL)isanoninvasive ,almostpain freestandardtreatmentmodalityforurolithiasis.However ,ESWLisnotcompletelyfreeofsideeffect.Apartfromlocalhematomasanda potentialriskforhypertensionchanges,alterationsinkidneyfunctionhavebeenreported .SalviaMiltiorrhizaehasthe propertyofpromotingbloodcirculationandresolvingbloodsta sis.Thisstudywasinitiatedtoinvestigatethepo tentialprotectivefunctionofSalviaMiltiorrhizaeeagainsthigh energyshockwaveinducedrenaltoxi city .MATE…     

结构多位置损伤的线性诊断方法

引入了一阶振型变化率的概念，并且证明了一阶振型变化率具有可叠加性，多位置损伤所引起的一阶振型变化率是各单位置损伤引起的一阶振型变化率的线性叠加．以一阶振型变化率为损伤标识量，将结构的多位置损伤状态等价于各单位置损伤状态的叠加．列出了结构多位置损伤的线性损伤诊断方法的实现步骤．以简支梁和四边固支的正方形板的多位置损伤诊断为算例表明，该方法不仅可准确地判定结构的损伤状态，而且损伤诊断的过程简单．     

运营期斜拉桥桥梁承载能力评定

结合对淮安大桥的桥梁承载能力评定,阐述运营期桥梁承载能力评定的一般方法和步骤,通过具体的评定流程,介绍桥梁缺损状况检查、桥梁材质状况及状态参数检测、桥梁结构检算以及最终承载能力评定的内容和方法。     

火灾后桥梁结构的损伤检测及安全性评估

通过对南京长江大桥火灾现场调查和造成的桥梁损伤的检测,分析了钢筋和混凝土构件损伤情况,估计了火灾现场、火灾温度。根据相关资料和荷载试验对桥梁安全状态进行了评估,为桥梁的修复、加固提供依据。     

ONE PROBABLE MECHANISM OF THE LEARNING-MEMORY DAMAGE BY LEAD:THE CHANGES OF NOS IN HIPPOCAMPUS

Leadtoxicityremainsapublicproblemintheworld ,especiallyinthedevelopingcountries.Chronicleadexposurecancauseimpairmentofcog nitivefunctionandsignificantdelaysinbehavioraldevelopment.However ,themechanismsunderly ingtheseimpairmentshavenotbeendefined .Long term potentiation (LTP)isthoughttobeavalidmodeloflearningandmemoryatthelevelofthesynapse[1] .Recently ,nitricoxidesynthase (NOS)hasbeenshowntobeanimportantfactorforforma tionandlastingofLTP[2 ,3 ] .Theremightbesomerelationsamonglead ,LTP…     

正己烷致大鼠脂质过氧化及肝细胞DNA损伤的实验研究

目的研究正己烷(n-hexane)对大鼠的脂质过氧化作用和肝细胞DNA损伤的影响。方法40只雄性SD大鼠随机分成5组,即阴性对照组、75、150、300 mg/kg染毒组和阳性对照组,每组8只。经腹腔注射染毒4周后,检测肝组织匀浆超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)的活力,血清还原型谷胱甘肽(GSH)和丙二醛(MDA)的含量;用彗星试验技术(SCGE)检测大鼠肝细胞DNA的损伤。结果大鼠体重随染毒时间而增加,阴性对照组增加最快;随染毒剂量增加,肝组织匀浆中SOD、GSH-Px活力、血清GSH含量明显降低,而血清MDA含量增大,组间比较有显著性差异(P<0.05或P<0.01);肝细胞SCGE检测彗星尾长、尾DNA(%)、尾矩、Olive尾矩均增大,组间比较有显著性差异(P<0.01),尾矩值与染毒剂量作相关分析,相关系数r为0.981,呈正相关(P<0.05)。结论正己烷可引起或增强机体氧自由基反应,导致脂质过氧化损伤和肝细胞DNA损伤。