Effects of job demands and social interactions on fatigue in short sea cargo shipping

Although fatigue is considered an important problem in shipping, little is known about potential mitigating factors or resources for coping. Adopting a Job Demands–Resources framework, this article examines the effects of both job demands (stressors) and resources on fatigue, focusing on social interactions on board as a potential source of social support. Using an incomplete repeated-measures design, the study combined information from documents with surveys on seven cargo ships. Findings indicated that fatigue levels were highest for those working on deck and for individuals at higher hierarchical levels. Higher numbers of port calls (and to some extent lower numbers of days at sea) also increased fatigue levels. By contrast, night watches and the number of days in port had no effect on fatigue. Supportive social interactions reduced fatigue (main effect), but their effect was weaker when the number of port calls increased (interaction effect). All main effects were mediated by individuals’ perceptions of work pressure. Taken together, findings highlight the importance of considering social interactions on board to advance our understanding of stressors and strain in seafaring.     

基于RHC-GA的多跑道进离场航班多目标动态优化模型

以管制负荷与航班延误总成本最小为目标函数,以尾流间隔、跑道限制与最大位置约束为约束条件,结合中国民航最新运行标准,建立了基于滚动时域控制策略的多跑道进离场航班多目标动态优化模型。针对模型求解规模庞大的特点,结合滚动时域控制策略的动态特性,设计了求解模型的遗传算法,选取中国某大型繁忙机场高峰时段的48个航班数据进行实例验证。仿真结果表明:当重、中、轻3种机型的单位飞行成本分别为25、16、10元·s-1时,采用现有先到先服务的策略,总延误损失为36 098元,管制负荷为32架次;当采用5个滚动时域的控制策略时,总延误损失为28 900元,管制负荷为31架次;当采用4个滚动时域的控制策略时,总延误损失为27 375元,管制负荷为32架次;当采用3个滚动时域的控制策略时,总延误损失为27 194元,管制负荷为33架次。与现有的先到先服务策略相比,提出的模型能动态地优化多跑道进离场航班排序问题,有效减少延误损失,并均衡跑道资源利用状况。     

对加快五凤头桥改建工程进度的有效分析

介绍了五凤头桥改建工程的进度安排和进度保证措施,以及五凤头桥改建工程进度控制在实施中取得的成效。同时从公路工程施工进度控制的基本原理入手,结合洪山口-火石营线五凤头桥改建工程的施工实践,分析了如何处理进度、质量、成本以及安全之间的矛盾。     

装备研制进度风险管理研究

进度风险是新装备研制面临的重要风险之一,它与计划、技术等因素密切相关。该文分析了装备研制进度风险的影响因素,总结了网络计划技术在进度风险评估分析中的应用,并就如何进行风险控制进行了研究。     

Optimization of periodic crew schedules with application of column generation method

We present an alternative approach to the problem of periodic crew scheduling. We introduce the concept of frames which leads us to a modeling approach which suits well the current practice of the majority of European railway operators. It results in a model facilitating column generation techniques resulting in a Dantzig-Wolfe type decomposition, and thus suitable for a parallel implementation in a high-performance computing environment. We exploit the properties of network flow models to avoid several additional integer constraints. We compare two approaches to solve the problem. The first approach consists of solving the original problem by single model. The second approach is our step-by-step column generation. The comparison is based on our implementation which we describe in detail along with its application to certain benchmark instances. The benchmarks originate in real or close-to-realistic problems from railway systems in Slovakia and Hungary. The case studies demonstrate that our model is well-suited for real-life applications.     

Understanding individual travel decisions: results from a commuters survey in Geneva

In this paper, we present the results of an extended traveler behavior survey conducted in Geneva (Switzerland) in March 1994. In this survey, commuters were asked about the impact of various factors, related to individual or household characteristics and situational, contextual and environmental constraints on their basic travel decisions. In particular, the issues of mode, route and departure time choice were investigated, together with the diversion from normal patterns in response to adverse weather conditions. Some cross cultural comparisons are discussed with respect to the results of a similar survey conducted in Brussels (Belgium) in 1992 (Khattak & de Palma 1995, 1997).     

杭州地铁工程进度计划管理

文章结合杭州地铁建设实践，介绍了工程进度计划管理的组织、流程和经验，指出进度管理过程中存在的问题并提出相应的解决方案，最后就如何加快地铁建设提出几点建议，为其他城市地铁进度计划管理提供参考。     

成兰铁路茂县隧道大变形特征及施工技术

针对成兰铁路茂县隧道斜井和正洞挤压性大变形段采用常规控制措施未取得预期效果的问题，从软岩隧道大变形特征和施工技术手段入手，提出锚杆工艺改进措施，并对斜井变形情况、正洞锚杆工艺改进前后隧道变形和施工工期进行分析。结果表明： 1）大变形段水平收敛变形突出，变形时间长、速率大，斜井部分断面变形跳跃式增长； 2）斜井段变形量受断面形状影响最大，变形速率受开挖尺寸和埋深的影响最为明显； 3）锚杆施工质量对大变形控制起关键作用，可从用水量、成孔质量、水灰比和注浆方式等方面对锚杆施工工艺进行改进； 4）锚杆施工工艺调整后，段落平均变形值减小32.11%~58.86%，左右洞工期速度分别提升约172.73%和77.23%。     

Variations in household transport expenditure within major Australian cities

A comparative analysis of intra‐urban variations in household transport expenditure in 1966–68 is undertaken for the two largest Australian cities, Sydney and Melbourne, and one of the smaller State capitals, Adelaide. Regional variations in transport expenditure are found to be greater the larger the city; however residents of small cities are more dependent upon the car for their motorised travel. In the larger cities car dependence is most evident among low‐to‐middle income groups at a relatively early stage in the life cycle, located in outer suburban areas. Consequently high levels of expenditure on transport typically coincide with relatively high levels of financial commitments to home purchase and/or operation. This has significant ramifications for the household budget, the most notable being deficit‐funding, and reduced outlays on other expenditure items such as recreation and education. The distribution of company vehicles and allowances is shown to be of relatively greater benefit to higher income groups, although is not confined to them. Although somewhat dated, the findings suggest that the social impacts of rising prices for energy will almost certainly be regressive.

Note: This paper was presented to the 7th PTRC Summer Annual Meeting held at the University of Warwick in July 1979. The authors gratefully acknowledge the contribution of the Australian Road Research Board in the preparation of the paper. Particular appreciation is expressed to Dr. M. R. Wigan, Mr. K. Sharp and Dr. M. G. Lay for their helpful comments.     

路桥工程中不同施工阶段的管理措施分析

施工阶段的管理内容包括对成本、质量、进度以及安全的管理,只有做好这几方面的管理才可以促进路桥工程施工的进程,实现预期的目的.对路桥工程不同施工阶段的管理进行详细分析,以期为相关的实践提供理论基础.