ANFIS model for assessing near-miss risk during tanker shipping voyages

Adaptive neuro-fuzzy inference system (ANFIS) was applied to predict the risk of near-miss incidents during tanker shipping voyages. Firstly, near-miss incidents recorded by a global tanker shipping management company were analysed. Four variables—type of operation, vessel’s location, on-board position, and harm potential were selected to train and predict the risk levels of near-miss incidents. The selected variables were found to be correlated with the observed frequency at three risk levels, namely low, medium and high. Gravity factor (GF) was calculated using the frequency of the categories in each variable and their associated risk levels. The calculated GF values and the risk levels of near-miss incidents were used as input values in the ANFIS model. Triangular, Trapezoidal and Gaussian membership functions were used. Subsequently, fuzzy logical theory and artificial neural networks were applied to train the data. Causal factors in terms of direct contributory factors, indirect contributory factors and root contributory factors to the near-miss incidents were analysed. Risk control measures were also proposed to improve safety during tanker shipping.     

动态载荷作用下焊接点线弹性裂纹的弯曲扩展路径的预测(英文)

利用二阶摄动方法研究了动态载荷作用下结构线弹性断裂裂纹的弯曲延伸扩展问题并求解了动态应力强度因子。利用二阶摄动方法研究了动载荷作用下裂纹路径预测时的应力准则与能量准则之间的关系。就均匀物质而言,在二阶摄动分析理论的框架内,两种准则指明了相同的动态裂纹路径。但在具有非均匀断裂韧度的物质中,能量准则优越于应力准则。作为二阶摄动方法的实际运用,研究了焊接结构中动态线弹性裂纹的形态特征和弯曲扩展路径问题,综合考虑了诸如远场动态作用应力、焊接残余应力、局部物质衰变以及不同尺寸的缺陷的存在等因素,绘制出动态载荷作用下退化区域中裂纹弯曲扩展的临界轨迹曲线。     

基于环境因素和基准化原理的信息资源配置研究

针对维修信息资源特点,以装备维修系统投入、产出为双目标,兼顾决策者偏好,引入环境背景值及针对多阶段过程的时间窗,建立装备维修信息资源优化配置DEA模型,并采用基准化思想评价资源配置效率。算例分析结果符合实际,最优结果和效率评价分析为决策者提供决策支持,利于提高装备维修保障效用,充分发挥装备维修资源作用。     

农村公路二灰碎石基层平整度影响因素与控制措施

二灰碎石基层平整度问题,是公路工程普遍存在的技术难题。探索二灰碎石基层平整度控制措施,解决困绕农村公路建设的技术难题,是各地交通公路部门正在着力研究的重要课题。本文从工程实践的角度出发,认真分析影响二灰碎石基层平整度指标的各种因素,探讨提高路面基层平整度的改进措施,提出了有效控制二灰碎石基层平整度的施工方法。     

项目经理工作绩效的控制

从理性角度出发,分析了影响项目经理工作绩效的主要因素,并着重分析了项目经理岗位竞争程度、薪酬收入和个人声誉影响三种因素;并基于此,构建了一个描述项目经理工作绩效的多参数方程组数学模型,并进行了分析讨论;最后,还对如何提高项目经理的工作绩效控制效果提出了一些对策建议。     

三体船耐波性预报

应用三维势流理论,计算了三体船在不同航速下垂荡、纵摇、横摇运动频率响应函数。预报了三体船在不规则波中各种海况下航行时的运动和加速度有义值,同时分析了三体船在西北太平洋海区一定海况下的运动特征和规律,最终根据舰船耐波性衡准要求,确定了三体船适合航行的海况与航速,为三体船耐波性方面得出了有价值的参考。     

沥青混凝土路面平整度探析

如何保证沥青混凝土路面的平整度,提高路面工程的质量,是高等级公路建设中的难点、重点。分析影响路面平整度的因素,从基础处理、材料控制、施工工艺等方面提出改善路面平整度的措施。     

大型舰船平台购置费影响因素及其预测技术方法研究

在分析大型舰船平台建造特点的基础上,研究了大型舰船平台购置费的影响因素,以此构筑了大型舰船平台购置费预测的基本要素。针对大型舰船没有国内以往费用数据样本可供参考的特点,在其生命周期的前两个阶段：论证阶段提出了基于等工程价值比的购置费预测技术方法;方案阶段借用费用风险因子方法的思想,结合风险评估中的技术成熟度,提出了基于费用风险因子和技术成熟度的类比预测方法。依据建立的大型舰船购置费预测技术方法思路,利用国外大型舰船以及国内外驱护舰的费用数据资料,可具体开展大型舰船平台购置费的预测工作,为大型舰船的立项决策以及方案选择提供理论支撑。     

Numerical Calculation of Marine Propeller Hydrodynamic Characteristics in Unsteady Flow by Boundary Element Method

In this paper, a low-order potential based on surface panel method is used for the analysis of marine propellers in unsteady flow.A linear propeller wake model is employed and its geometry is assumed to be independent of the time.The calculation in time domain is carried out from a moment when the rotation of the propeller becomes steady instead of from the moment when the rotation strats from stationary condition.At every time step a linear algebraic equation established on a key blade is solved numerically combined with the Kutta pressure conditon.The calculated results by developed code indicate good convergency and effrctiveness of present algotithm for conventional propellers and highly skewed propellers.     

Stress concentration factors at welds in pipelines and tanks subjected to internal pressure and axial force

In this paper, analytical expressions for stress concentration factors in pipes subjected to internal pressure and axial force are derived for a number of design cases based on classical shell theory. The effect of fabrication tolerances in simple butt welds is assessed. Analyses based on classical mechanics are compared with results from axisymmetric finite element analyses for verification of the presented methodology. Stress concentration factors are presented for circumferential butt welds in pipes welded together from pipes with different thicknesses, welds at buckling arrestors, welds at flanged connections in pipelines, and welds at ring stiffeners on the inside and the outside of the pipes. It also includes stress concentration factors at end closures in pipes for gas storage. Larger pipes are fabricated from plates with a longitudinal weld. This fabrication process introduces out-of-roundness in the pipes. The actual out-of-roundness is a function of internal pressure. An analytical expression for the bending stress in the pipe wall due to this out-of-roundness is presented. The derived stress concentration factors can be used together with a hot spot stress S–N curve for calculation of fatigue damage.