Using DIRECT to solve an aircraft routing problem

“The original publication is available at www.springerlink.com”. Copyright Springer DOI: 10.1023/A:1013729320435Peer reviewe

A global optimization approach to solve multi-aircraft routing problems

"This chapter appears in Computational Models, Software Engineering and Advanced Technologies in Air Transportation edited by Dr. Li Weigang and Dr. Alexandre G. de Barros. Chap.12 pp.237-259. Copyright 2009. Posted by permission of the publisher."This paper describes the formulation and solution of a multi-aircraft routing problem which is posed as a global optimization calculation. The paper extends previous work (involving a single aircraft using two dimensions) which established that the algorithm DIRECT is a suitable solution technique. The present work considers a number of ways of dealing with multiple routes using different problem decompositions. A further enhancement is the introduction of altitude to the problems so that full three-dimensional routes can be produced. Illustrative numerical results are presented involving up to three aircraft and including examples which feature routes over real-life terrain data

Implications of HGV charging for the UK

Road transport taxation in Europe is undergoing a major and radical shift away from fixed charges and fuel duties towards pricing according to distance travelled and externalities produced. Implementation is underway in some states, change being led by national schemes for the freight sector only. The UK is considering such a system for implementation by 2008, to use global positioning system technology. The paper reviews the current developments and considers charging scenarios, including a scenario for covering the full external costs of the UK freight industry. Implications for taxation policy are considered, including whether the doctrine of revenue neutrality is consistent with 'sustainable mobility'. Consideration is given to a transition strategy which could bridge between the current level and structure of prices and a future, more economically efficient approach

Any Time? Any Place? The impact on student learning of an on-line learning environment.

Original paper can be found at: http://www.actapress.com/Content_of_Proceeding.aspx?proceedingID=292#pages Copyright ACTA Press [Full text of this paper is not available in the UHRA]An increasing number of HE institutions are adopting virtual and managed learning environments (VLEs and MLEs), which offer flexible access to on-line learning materials all day and every day. There are multiple claims about e-learning enhancing learning and teaching (eg. [1] Britain and Liber, 1999; [2]Conole, 2002; [4]Allen, 2003; [5]Littlejohn and Higginson, 2003) such as supporting active learning, facilitative rather than didactic teaching and increased student motivation but these are not pre determined outcomes. Much depends on how lecturers use the available technology and how students respond to that use. This paper reports on a research project which has evaluated the students' own experience of on-line learning at the University of Hertfordshire. Using its own institution-wide MLE (StudyNet) academic staff at the university have been able to offer students on-line access to their study material from September 2001. Activities available for students using StudyNet include participating in discussion forums, using formative assessment materials and accessing journal articles as well as viewing and downloading courseware for each of their courses. Students were invited to participate in a questionnaire and focus groups to identify the characteristics of the on-line learning environment which benefited their learning

‘Good’ evidence for improved policy making: from hierarchies to appropriateness

Within the field of public health, and increasingly across other areas of social policy, there are widespread calls to increase or improve the use of evidence for policy making. Often these calls rest on an assumption that improved evidence utilisation will be a more efficient or effective means of achieving social goals. Yet, a clear elucidation of what can be considered ‘good evidence’ for policy use is rarely articulated. Many of the current discussions of best practice in the health policy sector derive from the evidence-based medicine (EBM) movement, embracing the ‘hierarchy of evidence’ in framing the selection of evidence – a hierarchy that places experimental trials as preeminent in terms of methodological quality. However, there are a number of difficulties associated with applying EBM methods of grading evidence onto policy making. Numerous public health authors have noted that the hierarchy of evidence is a judgement of quality specifically developed for measuring intervention effectiveness, and as such it cannot address other important health policy considerations such as affordability, salience, or public acceptability (Petticrew and Roberts, 2003). Social scientists and philosophers of knowledge have illustrated other problems in the direct application of the hierarchy of evidence to guide policy. Complex or structural interventions are often not conducive to experimental methods, and as such, a focus on evidence derived from randomised trials may shift policy attention away from broader structural issues (such as addressing the social determinants of health (Solar and Irwin, 2007)), to disease treatment or single element interventions. Social and behavioural interventions also present external validity problems to experimental methods and meta-analyses, as the mechanisms by which an intervention works in one social context may be very different or produce different results elsewhere (Cartwright, 2011). In these cases, policy makers may be better advised to look for evidence about the mechanism of effect, and evidence of local contextual features (Pawson et al., 2005). We argue that rather than adhering to a single hierarchy of evidence to judge what constitutes ‘good’ evidence for policy, it is more useful to examine evidence through the lens of appropriateness. It is important to utilise evidence to improve policy outcomes, yet the form of that evidence should vary depending on the multiple decision criteria at stake. Policy makers must therefore start by articulating their decision criteria in relation to a given problem or policy, so that the appropriate forms of evidence can be drawn on – from both epidemiological and clinical experiments (e.g. for questions of treatment effect), as well as from social scientific, social epidemiological, and multidisciplinary sources (e.g. for questions of complex causality, acceptability, human rights, etc.). Following this selection of types of evidence on the basis of appropriateness, the rigour and quality of the research can be assessed according to the evidentiary best practice standards of the discipline within which the evidence was produced. This approach speaks to calls to improve the use of evidence through ensuring rigour and methodological quality, yet recognises that good evidence is dictated by specific public health or social policy goals