Dominance-Based Heuristics for One-Machine Total Cost Scheduling Problems

International audienceWe study the one-machine scheduling problem with release dates and we look at several objective functions including total (weighted) tardiness and total (weighted) completion time. We describe dominance rules for these criteria, as well as techniques for using these dominance rules to build heuristic solutions. We use them to improve certain well-known greedy heuristic algorithms from the literature. Finally, we introduce a Tabu Search method with a neighborhood based on our dominance rules. Experiments show the effectiveness of our techniques in obtaining very good solutions for all studied criteria

The anonymous subgraph problem

In this work we address the Anonymous Subgraph Problem (ASP). The problem asks to decide whether a directed graph contains anonymous subgraphs of a given family. This problem has a number of practical applications and here we describe three of them (Secret Santa Problem, anonymous routing, robust paths) that can be formulated as ASPs. Our main contributions are (i) a formalization of the anonymity property for a generic family of subgraphs, (ii) an algorithm to solve the ASP in time polynomial in the size of the graph under a set of conditions, and (iii) a thorough evaluation of our algorithms using various tests based both on randomly generated graphs and on real-world instances

Markers of physiological stress during exercise under conditions of normoxia, normobaric hypoxia, hypobaric hypoxia and genuine high altitude.

Purpose To investigate whether there is a differential response at rest and following exercise to conditions of genuine high altitude (GHA), normobaric hypoxia (NH), hypobaric hypoxia (HH) and normobaric normoxia (NN). Method Markers of sympathoadrenal and adrenocortical function (plasma normetanephrine [PNORMET], metanephrine [PMET], cortisol), myocardial injury (highly sensitive cardiac troponin T [hscTnT]) and function (N-terminal brain natriuretic peptide [NT-proBNP]) were evaluated at rest and with exercise under NN, at 3375 m in the Alps (GHA) and at equivalent simulated altitude under NH and HH. Participants cycled for 2 hours {15 minute warm-up, 105 minutes at 55% Wmax (maximal workload)} with venous blood samples taken prior (T0), immediately following (T120) and 2 hours post-exercise (T240). Results Exercise in the three hypoxic environments produced a similar pattern of response with the only difference between environments being in relation to PNORMET. Exercise in NN only induced a rise in PNORMET and PMET. Conclusion Biochemical markers that reflect sympathoadrenal, adrenocortical and myocardial responses to physiological stress demonstrate significant differences in the response to exercise under conditions of normoxia versus hypoxia while NH and HH appear to induce broadly similar responses to GHA and may therefore be reasonable surrogates

Ordonnancement sur machines parallèles: minimiser la somme des coûts.

We study four parallelmachines scheduling problems. These problems are different by the criterion to minimize : the total completion time, the total weighted completion time, the total tardiness or the total weighted tardiness. Jobs can not be processed before release dates and preemption is forbidden. We have proposed several dominance rules for these problems. A complete study of lower bounds, existing and new ones, is also provided.Finally, we have presented a Branch&Bound method to solve exactly those problems, which takes advantage of lower bounds and dominance rules.Nous étudions quatre problèmes d'ordonnancement sur machines parallèles. Ces quatre problèmes diffèrent par le critère que l'on cherche à minimiser : la somme des dates de fin, la somme pondérée des dates de fin, le retard total ou le retard total pondéré. Les jobs à ordonnancer sout soumis à des dates de disponibilité. Nous avons proposé pour ces quatres problèmes plusieurs règles de dominance. Une étude des bornesinférieures a également été réalisée. Enfin, nous avons proposé une méthode de résolution exacte utilisant les règles de dominance ainsi que les bornes inférieures

Ordonnancement sur machines parallèles (minimiser la somme des coûts)

Nous étudions quatre problèmes d'ordonnancement sur machines parallèles. Ces quatre problèmes diffèrent par le critère que l'on cherche à minimiser: la somme des dates de fin, la somme pondérée des dates de fin, le retard total ou le retard total pondéré. Les jobs à ordonnancer sont soumis à des dates de disponibilité. Nous avons proposé pour ces quatre problèmes plusieurs règles de dominance. Une étude des bornes inférieures a également été réalisée. Enfin, nous avons proposé une méthode de résolution exacte utilisant les règles de dominance ainsi que les bornes inférieures.We study four parallel machines scheduling problems. These problems are different by the criterion to minimize : the total completion time, the total weighted completion time, the total tardiness or the total weighted tardiness. Jobs can not be processed before release dates and preemption is forbidden. We have proposed several dominance rules for these problems. A complete study of lower bounds, existing and new ones, is also provided. Finally, we have presented a Branch&Bound method to solve exactly those problems, which takes advantage of lower bounds and dominance rules.COMPIEGNE-BU (601592101) / SudocSudocFranceF

A 0-1 integer linear programming approach to schedule outages of nuclear power plants

International audienceWe address the problem of planning outages of nuclear power plants submitted by EDF (Électricité De France) as the challenge EURO/ROADEF 2010. As our team won the first prize of the contest in the senior category, our approach may be of interest: it is conceptually simple, easy to program and computationally relatively fast. We present both our method and some ideas to improve it

Three upper bounds for the speed meeting problem.

International audienc