影响船体爬壁除锈效率的参数试验研究

为提高超高压水射流船体爬壁除锈作业效率,对影响除锈效率的参数,应用正交设计方案,对行进速度、射流压力、喷嘴转速及喷嘴口径等关键参数,进行了正交设计匹配研究,同时,为进一步提高除锈效率,进行了影响除锈效率关键参数的优化匹配。     

破损船体的剩余极限强度分析

基于ABS和DNv规范关于剩余强度规范要求,对船舶碰撞与搁浅的破损部位和范围的假定,考虑了发生碰撞与搁浅破损后,其船体梁剩余有效剖面的非对称性和可能发生不同程度倾斜的情况,采用结构共同规范(CSR)中的逐步破坏分析方法和船体梁非对称剖面计算模型,分别计算了散货船和油船破损船体在两种破损模式和不同倾斜情况下的剩余极限强度,并对不同破损范围的影响进行了分析和比较。研究结果为协调结构共同规范(HCSR)的制定提供了有价值的参考。     

大型集装箱船绑扎桥结构优化设计

为有效降低大型集装箱船的空船重量,针对绑扎桥结构轻量化设计进行研究。以某14500TEU集装箱船为研究对象,根据船级社规范要求针对结构设计方案进行有限元计算分析,依次从剪力墙布置、立柱设置和局部尺寸优化等三个层次对原始方案进行优化设计。研究结果表明,优化方案在满足船级社规范要求、保证堆重指标的同时有效降低了绑扎桥的结构重量。本文的设计思路和优化方法可以为今后大型集装箱船绑扎桥的结构设计提供一定参考。     

Prioritizing road extension projects with interdependent benefits under time constraint

Since transportation projects are costly and resources are limited, prioritizing or sequencing the projects is imperative. This study was inspired by a client who asked: “I have tens of approved road extension projects, but my financial resources are limited. I cannot construct all the projects simultaneously, so can you help me prioritize my projects?” To address this question, the benefits and costs of all the possible scenarios must be known. However, the impacts (or benefit) of road extension projects are highly interdependent, and in sizable cases cannot be specified thoroughly. We demonstrate that the problem is analogous to the Traveling Salesman Problem (TSP). Dynamic change in travel demand during construction is another aspect of the complexity of the problem. The literature is yet to provide efficient methods for large cases. To this end, we developed a heuristic methodology in which the variation of travel demand during the construction period is considered. We introduce a geometrical objective function for which a solution-finding policy based on “gradient maximization” is developed. To address the projects’ interdependency, a special neural network (NN) model was devised. We developed a search engine hybridized of Ant Colony and Genetic Algorithm to seek a solution to the TSP-like problem on the NN based on gradient maximization. The algorithm was calibrated and applied to real data from the city of Winnipeg, Canada, as well as two cases based on Sioux-Falls. The results were reliable and identification of the optimum solution was achievable within acceptable computational time.     

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.     

Simplified buckling-and-contact-based expansion method for assessment of crashworthiness of double-hulled ship structure

Ship-to-ship collision events can have severe consequences such as loss of life and environmental degradation. For this reason, modern ship designs are required to incorporate a double-hulled structure to prevent inner-hull damage from such events. Using the experimental or numerical method to analyze the crashworthiness of double-hulled ship structures entails much effort, for which reason neither method is easy to adopt at the early design stage. In this paper, an existing simplified method called Ito's method is improved by a new buckling-and-contact-based expansion method. This method can be applied to double-hulled-structure or outer-hull-local-rupture failure mode. The perpendicular bow-to-side collision scenario is assumed for a conservative estimation of damage to a double-hulled structure. The method was verified in the present study by numerical ship collision simulations of several cases. The results for the buckling-and-contact-based expansion method and numerical simulation were similar for a blunt shape of striking body but different for a sharp shape.     

正常成人神经传导远端复合肌肉动作电位参数值正常范围的建立

目的确定正常成人神经传导远端复合肌肉动作电位(CMAP)末端潜伏时和波幅的正常值范围,为诊断周围神经病提供依据。方法对245例正常健康志愿者的正中神经、尺神经、胫神经及腓总神经进行常规神经传导速度测定,分析其末端潜伏时和波幅,其结果按照不同年龄段、性别、体重、左右侧肢体分别进行统计学分析。结果性别、体重、左右侧肢体对远端CMAP参数值的影响无明显统计学差异。年龄是最主要的影响因素,40岁前后变化最大,主要影响的是各神经远端CMAP的波幅和正中神经末端潜伏时,表现为随着年龄的增大,波幅逐渐减低,末端潜伏时逐渐延长。结论正常成人远端CMAP各参数的正常值范围按40岁前后两个年龄段确定比较合理和实用。     

波浪作用下库岸防护块体稳定分析

针对浪高不大的深水库,通过有、无波浪作用下库岸防护块体的抗滑、抗倾、抗浮稳定性对比分析,表明波浪作用下防护块体的稳定性显著降低,主要体现在波浪水流回落时刻引起的浮托力,并提出了砼板护面厚度的计算方法.     

基于UC3842的开关电源短路或过载保护的研究

通过分析基于UC3842的单端反激式开关电源典型电路,指出其"打嗝"方式的过载或短路保护的不足.针对不足之处,对典型电路进行修改,提出"关断保护"的过载或短路保护方式,并分析了此种保护方式的工作原理和优点.     

桥面平整度对连续梁桥动力响应的影响分析

不同等级桥面平整度对连续粱桥各特征截面的动力响应有一定的影响。相关研究表明，桥面平整度是车辆对桥梁产生冲击的一个重要因素，现行桥梁规范中的冲击系数公式仅适用于桥面状况比较良好的情况。