Evaluating the knowledge of experts in the maritime regulatory field

Regulations are introduced by the International Maritime Organization (IMO) into the maritime industry as the result of safety accidents and/or pollution incidents. When there is lack of historical data, then the IMO appoints experts in order to collect information regarding the costs and benefits generated to a stakeholder of the maritime industry once implementing a maritime regulation. Therefore, the role of experts in providing qualitative and quantitative information is crucial with respect to the quality of the maritime regulatory process within the IMO or other regulatory authorities. In this article, a methodology is proposed involving common criteria in determining the expertise of an individual in the maritime regulatory field. As essential part of the research methodology, analytic hierarchy process (AHP) is utilized to determine the expertise of an individual based on his/her own judgements. The regulatory authorities and other stakeholders of the maritime industry may use this method when selecting experts for decision-making. In this article, a simulation is carried showing the potentials of the AHP methodology in expertise evaluation followed by a case study.     

Urban single-lane roundabouts: A new analytical approach using multi-criteria and simultaneous multi-objective optimization of geometry design,efficiency and safety

Building safe and effective roundabouts requires optimizing traffic (operational) efficiency (TE) and traffic safety (TS) while taking into account geometric factors, traffic characteristics and local constraints. Most existing simulation-based optimization models do not simultaneously optimize all these factors. To capture the relationship among geometry, efficiency and safety, we put forward a model formulation in this paper. We present a new multi-criteria and simultaneous multi-objective optimization (MOO) model approach to optimize geometry, TE and TS of urban unsignalized single-lane roundabouts. To the best of our knowledge, this is the first model that uses the multi-criteria decision-making method known as analytic hierarchy process to evaluate and rank traffic parameters and geometric elements of urban single-lane roundabouts. The model was built based on comprehensive review of the research literature and existing roundabout simulation software, a field survey of 61 civil and traffic expert engineers in Croatia, and field studies of roundabouts in the Croatian capital city of Zagreb. We started from the basis of Kimber’s capacity model, HCM2010 serviceability model, and Maycock and Hall's accident prediction model, which we extended by adding sensitivity analysis and powerful MOO procedures of the bounded objective function method and interactive optimization. Preliminary validation of the model was achieved by identifying the optimal and most robust of three geometric alternatives (V.1-V.3) for an unsignalized single-lane roundabout in Zagreb, Croatia. The geometric parameters in variant V.1 had significantly higher values than in the existing design V.0, while approaches 1 and 3 in variant V.2 were enlarged as much as possible within allowed spatial limits and Croatian guidelines, reflecting their higher traffic demand. Sensitivity analysis indicated that variant V.2 showed the overall highest TE and TS across the entire range of traffic flow demand and pedestrian crossing flow demand at approaches. At the same time, the number of predicted traffic accidents was similar for all three variants, although it was lowest overall for V.2. The similarity in predicted accident frequency for the three variants suggests that V.2 provides the greatest safety within the predefined constraints and parameter ranges explored in our study. These preliminary results suggest that the proposed model can optimize geometry, TE and TS of urban single-lane roundabouts.     

浅埋顶管沉井周边土体的三维破坏形状及沉降研究

为研究顶管沉井及周边土体在顶进力作用下的形变范围与大小，以加固旋喷桩作为沉井周围加固体建立ABAQUS软件计算模型，并将模拟结果与工程实例、PLAXIS 3D软件所得结果进行对比分析。同时，采用广州地区花岗岩残积土进行室内沉井模型试验，并通过试验结果对数值模拟结论进行验证，得出结论如下： 1）在开挖基坑前达到设计强度的旋喷桩能有效减小基坑周边土体塌陷变形、坑底隆起。2）在施加工作顶推力下，前侧主动区首先出现贯通裂缝，竖向位移斜率增大出现明显拐点；继续增大顶推力，土体位移会急剧增大导致地表沉降严重。3）对于后背土体，在顶推力作用下，地表破裂线的切线角度从0°逐渐增大至45°+φ/2，导致破裂范围也不断扩大；达到45°+φ/2处后，继续施加顶推力会导致短轴方向破坏范围扩大的速度较长轴方向的速度更快；三维空间中被动区破坏土体在地表处产生形状为椭圆的破坏面，椭圆长轴方向为顶推轴线方向，被动破坏体呈现为牛角状椭圆楔体。     

基于物元分析法的公路桥梁损伤等级评定研究

在构建桥梁损伤等级评定指标体系的基础上，采用 AHP确定了各指标的权重，运用物元分析的方法建立了桥梁损伤等级评定的数学模型，并利用模型评定结果，得到了某桥梁的损伤等级。     

Travel time estimation oriented freeway sensor placement problem considering sensor failure

Optimal sensor placement on freeway corridor is of great interest to transportation authorities. However, current traffic sensors are easily subject to various failures. Therefore, it is necessary to incorporate sensor failure into the optimal sensor placement model. In this article, a two-stage stochastic model is proposed for the purpose of travel time estimation on freeway corridor. To balance the effectiveness and reliability, a stochastic conditional value at risk (CVaR) model is also proposed. Since both models are too complicated, a customized genetic algorithm is developed. Numerical experiments show that considering sensor failure makes a significant performance improvement in the sensor placement pattern. Sensitivity analysis is also applied to investigate the impact of a number of allowable sensors and different traffic sensor failure probability.     

柴油机气门导管断裂影响因素分析及改进

针对某柴油机气门导管在整机台架试验过程中发生的横断和纵裂失效故障,对气门导管的材料性能、结构应力、微动磨损、热变形、装配工艺等影响因素进行了分析。分析结果表明:材料力学性能差和装配过盈量较大造成的应力集中和微动磨损是气门导管横断的主要原因;液氮人工压装的装配工艺是造成气门导管纵裂的主要原因。据此提出新方案气门导管,并通过了整机台架试验验证。     

罗源洞特大桥变坡空心墩倒模施工技术

介绍了罗源洞特大桥变坡圆端形空心墩施工中采用的分节倒模施工技术,即先立一段墩身模板,完成该段墩身混凝土施工并达一定强度后,保留该段墩身模板的最上一层模板作为下一段模板生根之用,拆除其余墩身模板作为下一个桥墩的第一节模板。施工实践表明,该方法在保证施工质量的前提下可加快施工速度、节省投资。     

浅谈抱箍法盖梁施工

抱箍法作为无支架施工的一种新方法,在施工过程中体现出了其他方案不具备的优势。文章从实例出发,对抱箍的结构形式、受力计算、抱箍施工盖梁工艺等做了详细分析。     

华能曹妃甸煤码头工程陆域宽度优化设计

唐山港曹妃甸港区作为一个新兴港区,港口建设造陆工程对港区潮流、泥沙运动均产生影响,需要谨慎应对,以确保工程建设不对港区潮流和泥沙淤积造成不利影响。本文通过研究华能唐山港曹妃甸港区煤码头工程造陆宽度增加对港区潮流、泥沙运动产生的影响,加宽了堆场造陆宽度,优化了总体工艺设计方案。     

高等职业院校教学资源管理平台搭建初探

本文以高等职业教育教学资源管理平台开发为研究对象,在分析国内外教学资源平台发展状况的基础上,以辽宁省交通高等专科学校教学资源管理平台开发为依据,系统阐述了高等职业院校教学资源管理平台顶层设计内容、1+1+N平台运行模式、五层次用户管理模式、九模块自主添加功能、不公开信息处理功能等内容,对教学资源管理平台的主要功能进行了简明介绍,为高等职业院校教学资源管理平台开发与优化提供了很好的借鉴。