Nouvelle méthode intégrée pour résoudre le problème de planification et d'ordonnancement

2 pagesInternational audienceUne nouvelle méthode pour résoudre de manière intégrée le problème de planification et d'ordonnancement de la production dans des systèmes multi-niveaux est présentée. Des contraintes de capacité détaillées et de nomenclature sont inclues dans le modèle de planification, de manière à garantir des solutions réalisables. Une heuristique Lagrangienne et une heuristique de lissage sont utilisées pour résoudre le problème

New Integrated Approach For Solving Multi-level Lot Sizing and Scheduling problems

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Smoothing Procedures for an Integrated Approach for Multi-Level Lot Sizing and Detailed Scheduling

International audienceThe integration of production planning and scheduling decisions represents an important challenge in production management. Typical Enterprise Resource Planning (ERP) systems, using Manufacturing Resource Planning (MRP-II) technique for capacity management, cannot guarantee feasible procurement and production plans at the operational level (short term planning horizon). In this paper we study the integrated multi-level lot-sizing and job-shop scheduling problem. We analyze various smoothing procedures that "repair" the relaxed capacity and Bill-Of-Materials (BOM) constraints in the Lagrangian heuristic of a recent approach

Improvements of An Integrated Approach for Lot Sizing and Detailed Scheduling

4 pagesInternational audienceIn a previous work, we developed an integrated approach for determining optimal feasible production plans, i.e. lot sizes for which there is at least one schedule in which lots are completed on time. Based on the limitations of this approach, we propose various improvements in di fferent parts. The most relevant improvements are summarized in this extended abstract

In-building waste water heat recovery: urban-scale methods for the characterisation of water streams and the assessment of energy savings and costs

Residential domestic hot water (DHW) energy consumption represented 16% of the EU household heating demand in 2013. With the improvement of the building envelop, DHW contribution to energy consumption is expected to increase signi cantly, with values between 20% to 32% in single family buildings, and between 35% to almost 50% in multifamily buildings. This energy, currently lost to the environment, can be recovered by waste water heat recovery (WWHR) systems inside buildings (in-building solution). However, the characterisation of residential grey water streams at urban scale has barely been addressed. Also, the impact of such solutions on the total heating consumption and the related costs has not been assessed in detail for di erent types of residential buildings or for urban systems. The characterisation and geoallocation method of grey water streams as to mass ow and tem- perature level is therefore addressed. A method to quantify the energy saving potential and costs at urban scale of in-building WWHR systems in residential buildings is also proposed. These methods are applied in two case-studies, rst as retro tting solution in a city in Luxembourg and, second, as optimisation measure for high e ciency residential buildings. Grey water heat recovery would reduce the residential fuel consumption of the city by 6.3%. An integrated approach combining grey water heat recovery for hot water preheating and a heat pump yields up to 28% and 41% electricity savings for passive single family houses and multifamily buildings, respectively. With the detailed characterisation of various grey water streams in function of inhabitant number and end-use occurrence, the quanti cation of the energy savings and costs through heat recovery is improved. The outcomes of urban energy and cost assessments concerning grey water heat recovery are more speci c, as the results at building level are aggregated to the considered geographical scope. The proposed method therefore complements current urban energy and cost assessments with the detailed integration of in-building grey water heat recovery systems

A solution procedure for an integrated lot-sizing and scheduling problem

2 pagesInternational audienceAn integrated approach for solving single-level lot sizing and scheduling problems is presented. A Lagrangian heuristic and a smoothing procedure are combined, guaranteeing that detailed capacity constraints are respected in the lot sizing mathematical model

Characterisation of domestic hot water end-uses for integrated urban thermal energy assessment and optimisation

Former integrated urban energy assessments and optimisation have modelled domestic hot water (DHW) demand as a single stream, as space heating, currently, is the main energy demand in buildings and a detailed DHW modelling was therefore not required. However, the characterisation of energy saving measures (e.g. grey water heat recovery) and the selection of optimal heating utility in buildings with low temperature space heating would benefit from a differentiation of the various DHW end-uses at urban scale (building blocks, streets, districts, city). To this end, a new method characterising the main DHW appliances in households, hotels and nursing homes at urban level, is proposed. A review of European publications characterising water uses is conducted and utility load and energy consumption equations are developed. A specific model for district heating heat exchangers without thermal storage for integrated urban energy optimisation is proposed. The DHW-related energy consumption results are confirmed by literature values in a real urban case-study. Showering represents more than 80% of the DHW energy demand, and more than 97% of the total DHW heat use is required up to 40°C. The proposed method contributes to urban energy assessments and optimisation by improving the level of detail of the outcomes and by strengthening their integrated approach

Minimizing the Makespan for the Flow Shop Scheduling Problem with Availability Constraints

Article dans revue scientifique avec comité de lecture. internationale.International audienceThis paper deals with the scheduling of a flow shop with availability constraints (FSPAC). In such a problem, machines are not continuously available for processing jobs due to a preventive maintenance activity. A small number of solution methods exists in the literature for solving problems with at most two machines and to the author's knowledge only a few of them make use of the non-preemptive constraint. In this paper, two variants of the non-preemptive FSPAC with an arbitrary number of machines and an arbitrary number of unavailability periods on each of them are considered. In the first variant, starting times of maintenance tasks are fixed while in the second one the maintenance tasks must be performed on given time windows. Since the FSPAC is NP-hard in the strong sense, a heuristic approach based on a genetic algorithm and a tabu search is proposed to approximately solve the makespan minimization problem. Computational experiments are performed on randomly generated instances to show the efficiency of the proposed approaches