Search results for "Operations Research"
showing 10 items of 1297 documents
Statistics-driven Development of OBD Systems: An Overview
2006
Automotive on-board diagnostic (OBD) systems are designed to keep critical components under control during vehicle functioning, and to alert the driver in case of severe malfunctions. OBD systems aimed at reducing polluting emissions are mandatory on new motor vehicles. Some research projects conducted in cooperation between universities and the automotive industry have been quite successful in terms of knowledge advancement and industrial gain. An updated overview of the adopted methodologies and results obtained are given in this article. Such results can be valuable for both theorists and practitioners, since they witness the use of statistics as a powerful catalyst of technical progress…
Advances in vehicle routing and logistics optimization
2019
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A multiblock PLS-based algorithm applied to a causal model in marketing
2012
A statistical monitoring approach for automotive on-board diagnostic systems
2007
The current generation of vehicle models are increasingly being equipped with on-board diagnostic (OBD) systems aimed at assessing the ‘state of health’ of important anti-pollution subsystems and components. In order to promptly diagnose and fix quality and reliability problems that may potentially affect such complex diagnostic systems, even during advanced development prior to mass production, some vehicle prototypes undergo a testing phase under realistic conditions of use (a mileage accumulation campaign). The aim of this work is to set up a statistical tool for improving the reliability of the OBD system by monitoring its operation during the mileage accumulation campaign of a new vehi…
An optimization approach for communal home meal delivery service
2009
Abstract: This paper is the first to discuss the communal home meal delivery problem. The problem can be modelled as a multiple travelling salesman problem with time windows, that is closely related to the well-studied vehicle routing problem with time windows. Experimental results are reported for a real-life case study from Central Finland over several alternative scenarios using the SPIDER commercial solver. The comparison with current practice reveals that a significant savings potential can be obtained using off-the-shelf optimization tools. As such, the potential for supporting real-life communal routing problems can be considered to be important for VRP practitioners.
Estimation des modèles dynamiques à erreurs composées avec autocorrélation par la méthode des variables instrumentales
1996
In this paper, we consider a dynamic error-components models with autocorrelated disturbances. We analyse the efficient estimation procedure of autocorrelation parameter and we try to find out whether moment conditions of a dynamic model without autocorrelation are valid when the model includes autocorrelation. We propose two efficient estimation methods of autocorrelation parameter in addition to Baltagi and Li (1994) estimator. We show that all moment conditions of a dynamic model without autocorrelation are not valid in dynamics errors-components models with autocorrelated disturbances.
Behaviour of common estimators in dynamic error-components models with autocorrelated disturbances
1997
The purpose of this paper is to make a presentation of the properties of a set of estimators comprising the within, between, OLS and GLS estimators in the study of dynamic error - components models with autocorrelated disturbances. We underline in this study the importance of the statistical distribution governing the initial values for the process and the structure of xit variable for the limiting values of the estimators when the temporal dimension is fixed but the individual dimension N grows indefinitly.
External knowledge sourcing in different national settings: a comparison of electronics establishments in Britain and France
2004
04001; International audience; In a detailed comparison of matched samples of electronics establishments in Britain and France, this paper finds that the two samples of establishments were operating in distinctively different national labour markets for engineers and scientists, reflecting structural differences in national higher education systems and a far higher level of individual mobility between enterprises in Britain than is found in France. These differences were found to have very little effect on quantitative measures of establishments' external research interactions which tended to reflect other national-institutional differences such as continued government support for public la…
Energy saving in WWTP: Daily benchmarking under uncertainty and data availability limitations
2016
Efficient management of Waste Water Treatment Plants (WWTPs) can produce significant environmental and economic benefits. Energy benchmarking can be used to compare WWTPs, identify targets and use these to improve their performance. Different authors have performed benchmark analysis on monthly or yearly basis but their approaches suffer from a time lag between an event, its detection, interpretation and potential actions. The availability of on-line measurement data on many WWTPs should theoretically enable the decrease of the management response time by daily benchmarking. Unfortunately this approach is often impossible because of limited data availability. This paper proposes a methodolo…
Constraint qualifications and Lagrange multipliers in nondifferentiable programming problems
1994
In this paper, we present several constraint qualifications, and we show that these conditions guarantee the nonvacuity and the boundedness of the Lagrange multiplier sets for general nondifferentiable programming problems. The relationships with various constraint qualifications are investigated.