Search results for "Production proce"

2014

This paper presents a mathematical model for robust production planning. The model helps fashion apparel suppliers in making decisions concerning allocation of production orders to different production plants characterized by different lead times and production costs, and in proper time scheduling and sequencing of these production orders. The model aims at optimizing these decisions concerning objectives of minimal production costs and minimal tardiness. It considers several factors such as the stochastic nature of customer demand, differences in production and transport costs and transport times between production plants in different regions. Finally, the model is applied to a case study.…

Scheduling in a continuous galvanizing line

2009

In this paper we address a sequencing problem in a Continuous Galvanizing Line of a Spanish Steel Company. Production scheduling in this context is an extremely complex task which needs to take into account many constraints. We present a conceptually simple model and a Tabu Search (TS) algorithm that efficiently solves it. The TS moves are defined in order to repair non-satisfied constraints, leading to smaller and more efficient neighbourhoods. The TS co-ordinates several intensification and diversification procedures guided by an evaluation function based on a shifting penalty strategy. This function reinforces the anticycling mechanism and makes the algorithm avoid already visited soluti…

Teaching programming by emphasizing self-direction: How did students react to the active role required of them?

2013

Lecturing is known to be a controversial form of teaching. With massed classrooms, in particular, it tends to constrain the active participation of students. One of the remedies applied to programming education is to use technology that can vitalize interaction in the classroom, while another is to base teaching increasingly on programming activities. In this article, we present the first results of an exploratory study, in which we teach programming without lectures, exams, or grades, by heavily emphasizing programming activity, and, in a pedagogical sense, student self-direction. This article investigates how students reacted to the active role required of them and what issues emerged in …

Determinants of elimination decisions in the activity scheduling process

2016

[EN] This paper presents an analysis on the determinants related to a particular rescheduling decision in the activity-travel scheduling process: elimination decisions, which consist in the non-execution of pre-planned activity-travel episodes. Data used come from an in-depth computer-assisted telephone interview (CATI) follow up survey carried out during the implementation of the first wave of an activity scheduling process panel survey. Open-ended answers related to the reasons associated to changes between pre-planned and executed agenda are studied. First, an interpretative qualitative method based on analytic induction (AI) is used to cope with the complex nature of the rescheduling de…

Autonomous agent system using dispatching rules in the negotiation protocol

2002

In this paper, the most important results obtained by the simulated application of autonomous agent paradigms to a. real factory are presented. The classical rules of dispatching are compared with the autonomous agents approach. In particular, the possibility of redesigning the negotiation rules in terms of currency in order to take into account even non-time-related costs is considered. Finally, a new project on the effective application of the autonomous agent system to a test bed, modelling a simplified firm, is proposed.

Partially Renewable Resources

2014

In recent years, in the field of project scheduling the concept of partially renewable resources has been introduced. Theoretically, it is a generalization of both renewable and non-renewable resources. From an applied point of view, partially renewable resources allow us to model a large variety of situations that do not fit into classical models, but can be found in real problems in timetabling and labor scheduling. In this chapter we define this type of resource, describe an integer linear formulation and present some examples of conditions appearing in real problems which can be modeled using partially renewable resources. Then we introduce some preprocessing procedures to identify infe…

A hierarchic approach to production planning and scheduling of a flexible manufacturing system

1999

Abstract The paper deals with the problem of improving the machine utilization of a flexible manufacturing cell. Limited tool magazine space of the machines turns out to be a relevant bottleneck. A hierarchic approach for this problem is proposed. At the upper level, sets of parts that can be concurrently processed (batches) are determined. At the lower levels, batches are sequenced, linked, and scheduled. Methods taken from the literature are used for the solution of the latter subproblems, and an original mixed integer programming model is formulated to determine batches. The proposed methods are discussed on the basis of computational experience carried out on real instances.

Managing electrical energy storage systems and shiftable loads with an innovative approach in energy districts

2014

In this work, a power dispatch problem for a system composed of an aggregate of loads and an electrical energy storage system is considered. The approach to solve the optimal dispatch is innovative and shows good performances in limited calculation times. According to the more recent indications coming from the European distributors, the architecture for energy dispatch at distribution level will be hierarchical. The 'Aggregator' is the interface between groups of loads and the energy distributor and sends the individual consumers the desired load profiles, following which the user may gets a discount on the energy bill. On the other hand, the energy tariff may follow a given daily profile …

Simultaneous Airline Scheduling

2008

Currently, there are no solution approaches available to construct and optimize airline schedules within a single model. All existing approaches decompose the problem into smaller and less complex subproblems and solve those subproblems separately. This chapter presents a metaheuristic for simultaneous airline scheduling where several different subproblems are integrated into one single optimization model, except for crew scheduling. The problem-specific metaheuristic uses an adaptive procedure for operator selection to allow an efficient choice between a variety of different operators. Experiments are conducted as proof-of-concept and to calibrate free parameters. Comparing different searc…

Integrated Production and Predictive Maintenance Planning based on Prognostic Information

2019

International audience; This paper address the problem of scheduling production and maintenance operation in predictive maintenance context. It proposes a contribution in the decision making phase of the prognostic and health management framework. Theprognostics and decision processes are merged and an ant colony optimization approach for finding the sequence of decisions that optimizes the benefits of a production system is developed. A case study on a single machine composed of several components where machine can have several usage profiles. The results show thatour approach surpasses classical condition based maintenance policy.