阳宗海表层沉积物中的重金属生态风险评估

对从阳宗海湖底表层采集的25组沉积物样品中的10种重金属质量比进行分析,结果表明,Ti、Mn、Zn、V、Cr、Cu、Ni、Co、Pb和As的质量比平均值均超过了当地土壤背景值。而重金属系统聚类分析表明,Zn、Cr、Pb、As高度相关,其污染主要由于人类活动造成;Ti、Mn、V、Cu、Ni、Co的分布特征相似,其污染原因以岩石风化等自然因素为主。单因子富集系数评价表明,阳宗海10种重金属均达到了中度富集程度,其中As、Cu、Cr富集程度较为突出。用Hakanson潜在生态风险指数法评价阳宗海表层沉积物中重金属的生态风险,结果表明,阳宗海表层沉积物中重金属的生态风险总体属轻微程度,阳宗海南岸局部区域达到中等生态风险程度。几种重金属对阳宗海生态风险的贡献由大到小依次为As、Cu、Co、Ni、Pb、Cr、V、Zn、Mn、Ti,其中,As是阳宗海最突出的生态风险因子。     

金鸡滩水利枢纽悬挂式清污机设计

金鸡滩水利枢纽的悬挂式清污机是一种新型的清污机械,可以根据水电站的要求进行配套设计,能有效地解决拦污栅污物堵塞的问题,水下工作可靠,应用广泛,是老水电站清除拦污栅前污物堆积的升级改造设备。     

基于自由搜索的水库入库含沙量预测模型

水库泥沙淤积问题直接关系到水库的规模、寿命以及综合经济效益的发挥。入库水流含沙量是影响水库调度运行以及水库泥沙淤积的主要因素,目前国内结构简单、实用性较强的含沙量预测模型不多。以水库的入库站流量及上游站至入库站的区间流量为研究对象,提出了基于两个水文站流量的水库入库含沙量的预测模型,采用改进的自由搜索算法率定模型参数,并将模型应用于龚嘴水库的入库含沙量的预测。研究结果表明,构建的模型结构简单,参数率定便捷,预测含沙量的精度较高,为水库入库含沙量预测提供了一种简便适用的方法。     

Where to park? A behavioural comparison of bus Park and Ride and city centre car park usage in Bath,UK

Integrating car parking facilities with public transport in Park and Ride (P&R) facilities has the potential to shorten car trips, contributing to more sustainable mobility. There is an ongoing debate about the actual effects of P&R on the transport system at the subregional level. A key issue is the relative attractiveness of city centre car parks (CCCP), P&R and public transport. The paper presents the findings of a comparative empirical case-study based on a field survey of CCCP and P&R users conducted in the city of Bath, UK. Spatial and statistical analyses are applied. Radial distance to parking, availability of P&R sites in the direction of travel, gender, age, income and party-size are found to be important factors in a binary logistic regression model, explaining the revealed-preference of parking type. Stated analysis of foregone parking alternatives suggests more use of public transport and walking/cycling would likely occur without first-best parking alternatives. The policy implications and possible planning alternatives to P&R at the urban fringes for achieving greater sustainability goals are also discussed.     

The trade-off between fixed vehicle costs and time-dependent arrival penalties in a routing problem

This paper introduces the vehicle routing problem with soft time windows (VRPSTW) in which problem definition differs from ones previously defined in literature. Branch-and-price approach is employed, resulting in a set partitioning master problem and its new subproblem. Novel techniques are consequently developed to solve this new subproblem. Experimental results report the comparisons of these solution techniques under the branch-and-price framework. The VRPSTW solutions have further been compared to the state-of-the-art literature, signifying the superiority of the VRPSTW on this issue.     

An economic–geographic assessment of the potential for a new air transport hub in post-Gaddafi Libya

Post-war Libya is faced with the challenge of adopting an air transport strategy for the future. One issue is how to address projects inaugurated under the Gaddafi government, such as the terminal extension at Tripoli International Airport. Additionally, the state-owned Afriqiyah Airlines had been establishing a niche hub in Tripoli before the 2011 war, but this development has subsequently been stalled.Against this background, we analyse the prospects of an air transport hub operation in Libya, focusing on traffic between Africa and Europe, from a bird’s-eye economic–geographic view. First, a literature review is undertaken to identify general success factors for air transport hubs. Second, a weighted average distance penalty (WADP) indicator is developed and applied to Tripoli as a potential hub location. This indicator considers all 4755 O&Ds between Europe and Africa with more than 100 passengers in 2012. For sensitivity reasons, alternative WADPs are estimated for the 3209 traffic flows not including North Africa and for (forecasted) future air traffic demand in 2020. The results for Tripoli International Airport are benchmarked against competing hub locations, such as Algiers, Cairo, and the major European airports. We conclude by discussing the implications of the current and anticipated future security and economic situation in the country.     

山溪坝后式取水及明渠弯道除沙方式研究

随着我国水利水电工程建设的发展,水电站分布越来越集中于偏远山区,供水系统往往需自行建设。为了解决工程建设施工及生活用水问题,通常是将工程附近水源水质较好的山溪作为取水点,并经简单沉沙处理后投入使用。传统的坝前式山溪取水及大型沉沙池除沙普遍面临着汛期取水头部易被泥石流淤积、山溪内施工部位狭窄等问题,根据弯道环流原理,结合杨房沟水电站供水系统取水头部设计及运行使用经验,研究验证了坝后式取水代替传统的坝前式取水,以及明渠除沙代替大型沉沙池除沙方式的实际效果。实践表明,新的取水方式可以满足抗淤能力强、施工占地少,同时除沙能力理想的要求,可为今后类似情况下山溪取水及除沙方式的选择提供参考。     

Flagging out in road freight transport: a strategy to reduce corporate costs in a competitive environment: Results from a longitudinal study in Austria

Following the example of maritime transport, the relocation of fleets abroad – referred to as flagging out – has become an important cost reduction strategy for road freight transport companies. Particularly after the EU Eastern Enlargement in 2004, many Austrian road freight transport companies took advantage of both the freedom of services and the lower costs in New Member States. This paper shows the results of four waves of surveys of Austrian road hauliers, describing developments, attitudes, motives and impacts of the phenomenon. There is also a discussion about the significance of the problem, which was seldom referred to in the scientific literature.     

Sustainability in the Transport and Logistics Sector: Lacking Environmental Measures

Sustainability as part of the development of companies' business strategies is gaining in importance. Due to its impact on the environment, this is particularly essential for companies of the transport and logistics sector. This paper explores several factors that influence the environmental behaviour of transport and logistics companies in Austria. It discusses the importance of the economic impact on environmental management decision in detail and analyses the sector's specific characteristics in terms of environmental behavior. A case‐based approach involving multiple field studies with face‐to‐face expert interviews and secondary data analysis was used to evaluate environmental performance and specific practices. Using selected cases, we will demonstrate how environmental measures contribute to overall business performance and draw general conclusions regarding the transport and logistics sector. Furthermore, suggestions are given as to how the government can further support transport and logistics companies in this regard. Copyright © 2013 John Wiley & Sons, Ltd and ERP Environment.     

Socio-technical transition governance and public opinion: The case of passenger transport in Finland

As a governance perspective, transition management views the engagement of a wide variety of stakeholders in policy development as a necessary element in furthering sustainability through enhanced social learning. Yet as a literature it has paid relatively little attention to public consultation on socio-technical change. Here we set transition management in the context of longstanding debates in science and technology studies, technology assessment and deliberative democracy. Empirically, we use national survey data on Finnish public opinion of state support for future transport options. Showing how transport practices and attitudes to transport innovation policy vary with both demography and geography, we argue that these differences have implications for policy legitimacy. We suggest that, both given and despite the practical difficulties of deliberative democracy, use of participative opinion surveying to better understand social groups with needs and interests that differ from national averages, may help to enhance policy legitimacy and hence the success of transition management.