Analysis of principal trends of mobility related to location policy, car ownership, supply policy and ageing of population

In transport analysis, we generally have several correlative explanatory variables when we want to explain the evolution of a factor. Therefore the quantification of the contribution of each variable in the evolution of our study object is often problematic. This problem is well known in modelling even if not always well treated. In this case the evolution of the object cannot always be expressed simply (as a sum or a product) from the evolution of the explanatory variables. To take this question into account, we propose a method to break down and measure the effect of each explanatory variable. We have applied this method to two contexts which focus the thematic network on Society, Behaviour and Private/Public Transport.The first one deals with a retrospective analysis of the evolution of car ownership and car use of both elderly people and younger people. This analysis permits to quantify the contribution of different factors: demographic effect, car ownership effect and behaviour effect and their combination to quantify the evolution of the number of car trips in the population. This analysis has been conducted both in Lyon and Grenoble conurbation in south-east of France from several household surveys conducted between 1970 and 1995.The second one analyses the evolution of the share of public transport among motorised trips in the Lyon conurbation. This analysis allows to quantify the contribution of different factors: urban sprawl effect, car ownership effect, public transport supply effect, private transport supply effect and a residual effect which summarised unobserved variables and their combination to quantify the evolution of public transport share among motorised transport. It explains the apparent paradox of a very important increase in public transport supply in Lyon conurbation but a stability of the share of public transport between 1976 and 1995.Both analysis suggest interesting features both in term of prospective and urban policy. It appears that very strong socio-demographic trends act to reduce, when not cancel, the effect of important improvement in public transport supply as we can see in many French conurbation. From the quantification of different effects, we can simulate different future from which it appears that only global and comprehensive policy on all mode of transport and parking and on urbanism are able to reduce use of car in sustainable perspective.Urban mobility ; car ownership ; urban sprawl ; aging of population ; public transport ; trends ; cohort effect ; simulation

Valid inequalities for the single-item capacitated lot sizing problem with step-wise costs

This paper presents a new class of valid inequalities for the single-item capacitated lotsizing problem with step-wise production costs (LS-SW). We first provide a survey of different optimization methods proposed to solve LS-SW. Then, flow cover and flow cover inequalities derived from the single node flow set are described in order to generate the new class of valid inequalities. The single node flow set can be seen as a generalization of some valid relaxations of LS-SW. A new class of valid inequalities we call mixed flow cover, is derived from the integer flow cover inequalities by a lifting procedure. The lifting coefficients are sequence independent when the batch sizes (V) and the production capacities (P) are constant and if V divides P. When the restriction of the divisibility is removed, the lifting coefficients are shown to be sequence independent. We identify some cases where the mixed flow cover inequalities are facet defining. A cutting plane algorithmis proposed for these three classes of valid inequalities. The exact separation algorithmproposed for the constant capacitated case runs in polynomial time. Finally, some computational results are given to compare the performance of the different optimization methods including the new class of valid inequalities.single-item capacitated lot sizing problem, flow cover inequalities, cutting plane algorithm

Single item lot-sizing with non-decreasing capacities

We consider the single item lot-sizing problem with capacities that are non-decreasing over time. When the cost function is i) non-speculative or Wagner-Whitin (for instance, constant unit production costs and non-negative unit holding costs), and ii) the production set-up costs are non-increasing over time, it is known that the minimum cost lot-sizing problem is polynomially solvable using dynamic programming. When the capacities are non-decreasing, we derive a compact mixed integer programming reformulation whose linear programming relaxation solves the lot-sizing problem to optimality when the objective function satisfies i) and ii). The formulation is based on mixing set relaxations and reduces to the (known) convex hull of solutions when the capacities are constant over time. We illustrate the use and effectiveness of this improved LP formulation on a new test instances, including instances with and without Wagner-Whitin costs, and with both non-decreasing and arbitrary capacities over time.lot-sizing, mixing set relaxation, compact reformulation, production planning, mixed integer programming

Capacitated facility location: Valid inequalities and facets

Location Theory;Optimization;Capacity;econometrics

The European Pillar of Social Rights in historical perspective

A special 'Social Summit' is due to be held in Gothenburg on 17 November, where details of the European Pillar of Social Rights (EPSR) are expected to be announced. Philippe Pochet of the European Trade Union Institute has some advice for the European Union as it mounts one of its periodic attempts to recast its Social Union. He urges the EU to rebalance social and economic concerns by mounting an ambitious social programme

Greece: the triumph of an alternative narrative

Phillipe Pochet of the European Trade Union Institute in Brussels sees the recurring Greek debt crisis as emblematic of the conflict between markets and democrac

Le stage 2005 des bibliothécaires du groupe transversal ressources documentaires

Cet article décrit un stage de sept semaines organisé par le groupe transversal "ressources documentaires" de la CUD à l'intention des cadres des bibliothèques partenaires

Towards Sustainable Mobility Indicators: Application to the Lyons Conurbation

This paper applies the theme of sustainable development to the case of urban transport and daily mobility of the inhabitants of a city. A set of indicators which simultaneously takes the three dimensions of sustainability––environmental, economic, and social––into account is suggested. We present here the results of exploratory research funded by Renault Automobile Manufacturers, carried out to verify the feasibility and the usefulness of elaborating such sustainable mobility indicators. Values of the economics, environmental and social indicators are presented for the Lyons case. These estimations are mainly based on the household travel survey held in this city in 1994–1995. In the end, this set of indicators should allow the comparison of different urban transport strategies within an urban area, but also between different urban contexts, and through time. The conditions of generalization of these measurements of indicators are then discussed.Trip distance ; Daily mobility ; Sustainability indicators ; Household travel survey ; Methodology ; Pollutant emissions ; Expenditures ; Global costs