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Partitioning of large networks is vital for decentralized management and control. This paper presents two algorithms called 'Hierarchical Recursive Progression-1' (HRP-1) and 'Hierarchical Recursive Progression-2' (HRP-2) for partitioning of large networks into subnetworks of limited size with very few interconnections between them. In other words, we are trying to maximize the internal nodes and minimize the external connections of the subnetworks. The restriction on the size and the external connections is obtained by comparison against a user-defined value for the size of the subnetwork and for external connections via a term called density. The density of a subnetwork is defined as the ratio of the number of external connections and the size of the subnetwork. The two algorithms presented in the paper are based on the principle of subnetwork clustering. At the start of the algorithms, the number of subnetworks is equal to the total number of nodes of the network with each subnetwork containing a single node. Later, subnetworks are merged at various runs of the algorithm to form new subnetworks using connectivity, density and size criteria. The algorithms terminate when all the subnetworks satisfy a user-defined size and density limit. The difference between the algorithms HRP-1 and HRP-2 lies in the definition of density of subnetworks and the way through which the subnetworks are grouped at consecutive iterations of the algorithm. Note that the number of nodes inside the subnetworks never violates the size limit, thereby ensuring even distribution of load on the partitions obtained. Finally, the two algorithms are compared and tested on randomly generated graphs and a part of Paris road Network. Journal of the Operational Research Society (2010) 61, 1159-1167. doi: 10.1057/jors.2009.52 Published online 24 June 2009 Keywords: graph partitioning; large networks; distributed computing; load balancing

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2006.11.050 Byline: Gerd Finke (a), Pierre Lemaire (a), Jean-Marie Proth (b), Maurice Queyranne (a) Keywords: Parallel scheduling; Complexity; Minimum number of processors Abstract: In this paper, we present a new objective function for scheduling on parallel machines: minimizing the number of machines for schedules of minimum length. We study its complexity and we prove the NP-completeness of this problem, even if there is no precedences or for unitary execution times. We propose several polynomial algorithms for various particular cases. Author Affiliation: (a) Leibniz-IMAG, 46 Avenue Felix Viallet, 38 031 Grenoble cedex, France (b) INRIA-Lorraine, 615 Rue du Jardin Botanique, B.P. 101, F-54602 Villers-les-Nancy cedex, France Article History: Received 1 May 2005; Accepted 1 November 2006

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2005.06.078 Byline: Satyaveer S. Chauhan (a), Valery Gordon (b), Jean-Marie Proth (c) Keywords: WIP; Scheduling; No-wait Abstract: Successful companies are those that reach at least the two following objectives: reduce their Work-In-Process (WIP) and respond to customer's requirements in real time. The approach proposed in this paper allows to reach these goals by controlling the WIP and providing information about the completion times of customer's demands in real time. The approach we develop in this paper has been integrated in a supply chain environment for flow-shops. This paper extends the approach to assembly systems. Author Affiliation: (a) Bordeaux School of Management, Talence, France (b) National Academy of Sciences, Minsk, Belarus (c) INRIA-SAGEP, UFR Science, Universite de Metz, Ile du Saulcy, 57045 Metz, France Article History: Received 15 October 2004; Accepted 15 June 2005

The scheduling of real-time in minimizing the delays from a single source is examined.

Byline: Cyril Duron (1), Jean-Marie Proth (1) Keywords: Feature selection; [chi].sup.2 analysis; data mining; diagnosis; statistics Abstract: This paper addresses the 0--1 outcome feature selection problem. In such a problem, a set of features leads to an outcome that is 0 or 1, depending upon the values of the features. The aim is to extract subsets of features that characterize at best outcome 1. This kind of problem arises in medical analysis, quality control and, generally, in any domain that requires series of expensive tests to evaluate the state of a system. Author Affiliation: (1) INRIA/SAGEP, UFR Scientifique, Universite de Metz, Ile du Saulcy, 57000, Metz, France Article History: Registration Date: 30/09/2004

Application of heuristics to formulate algorithm for ascertaining cost of material supplied by various manufacturers to single customer, for fulfilment of preexisting demand, is described.

In this paper, the expression "production systems" refers to flow shops, job shops, assembly systems, Kanban systems, and, in general, to any discrete event system which transforms raw material and/or components into products and/or components. Such a system is said to be cyclic if it provides the same sequence of products indefinitely. A schedule of a cyclic production system is defined as soon as the starting time of each operation on the related resource is known. It has been shown that, whatever the feasible schedule applied to the cyclic production system, it is always possible to fully utilize the bottleneck resource. In other words, it is always possible to maximize the throughput of such a system. As a consequence, we aim at finding the schedule which permits to maximize the throughput with a work in process as small as possible. We propose a heuristic approach based on Petri nets to find a near-optimal, if not optimal, solution. We also give a sufficient condition for a solution to be optimal. Index Terms--Cyclic production systems, event graphs, Petri nets, scheduling, work in process (WIP).

A unified framework for addressing common due date assignment and scheduling problems is presented by surveying available operations research literature.

Two dynamic programming-based heuristic methods were suggested to solve different types of industrial cutting stock problems. The HCUS (Heuristic Constraining the Utilisation of the Stored Bars) method is utilized in the sales department, where the time to present a solution is more important than the quality of the solution. The HCUSO (Heuristic Constraining the Utilisation of Stored and Ordered Bars) method, however, focuses on the quality of the solution over time.

A class of Petri nets called Controllable-Output nets or CO nets was utilized to model schedulling in a manufacturing system. The CO nets allows the introduction of a two-stage scheduling algorithm for problems with piecewise constant product flows. The algorithm introduced involves the division of workload among resources and creation of a schedule based on resource workload.

This paper proposes a model and a related algorithm for generating optimal cyclic schedules of hoist moves with time window constraints in a printed circuit board (PCB) electroplating facility. The algorithm is based on the branch and bound approach and requires the solution of a specific class of linear programming problems (LPP's). These LPP's are equivalent to the problems of the cycle time evaluation in hi-valued graphs. Computational experience is presented to compare the results obtained using this new algorithm with the ones proposed in the literature. Index Terms - Bi-valued graph, branch-and-bound, cycle time, hoist scheduling, time window constraints.

Development of heuristics was undertaken to resolve office scheduling problem. Two assignment heuristics created showed effectiveness in terms of assigning tasks to employees and scheduling assigned tasks to resolve previously identified limitations. A developed intuitive heuristic, meanwhile, proved to be efficient in directly creating a viable schedule. A simulated annealing strategy was also employed in scheduling assigned tasks.

Byline: FABRICE CHAUVET (1), NEA'VINE HAFEZ (1), JEAN-MARIE PROTH (2), NATHALIE SAUER (3) Keywords: Logistics; self-service cars Abstract: This paper deals with the problem of self-service cars arising in large companies where cars are at the employees' disposal to travel between different company sites. This problem also occurs in some big cities where electric cars are available for customers to make local journeys. The employee (or the customer) uses the car to travel from one site to another, and leaves it there so that other employees (or customers) can use it. This customer will use another car to travel to another site, if necessary. In this paper, we restrict ourselves to the case where the random variables which generate car requirements in a given site are independent identically distributed (i.i.d.) random variables, and we study the behaviour of the system according to a balancing strategy. Author Affiliation: (1) INRIA-Lorraine, SAGEP Project, Technopo^le Metz 2000, 4 rue Marconi, 57070, Metz, France (2) Institute for Systems Research, University of Maryland, College Park, MD, 20742, USA (3) DeA'partement Automatique et Productique, Ecole des Mines de Nantes, BP 20722, 44307, Nantes Cedex 03 Article History: Registration Date: 09/09/2004

This paper introduces a class of Petri nets which are reversible, live, and can be kept bounded. Furthermore, these Petri nets have output transitions that can be fired independently from each other. These properties are required when modeling manufacturing systems. Another important property is that the integration of models which belong to this class of Petri nets still belongs to the same class, assuming that the integration is performed following rules which reflect common manufacturing practice. As a result, the qualitative properties of the module models are preserved. The results obtained in this paper are expected to shed light on the design, management and control of large scale manufacturing systems since modular approach is a way to cope with complexity. Index Terms - Integration, manufacturing systems, Petri nets.

An important step when designing a flexible manufacturing system (FMS) using automated guided vehicles (AGV's) is the definition of the number of AGV's to be used in order to reach a given productivity. A way to define this number is to consider several scenarios, to define the minimal number of AGV's required by each scenario, and to keep the maximal of these numbers. In this paper, we propose a branch and bound (B&B) approach to define the minimal number of AGV's required for a scenario. This approach is based on an event graph (EG) formulation. Index Terms - Automated guided vehicles, event graphs, flexible manufacturing systems, modeling, optimization, Petri nets, transportation systems.

Two heuristic procedures for solving flow shop scheduling problems with the objective function of minimizing the total job completion time in O(n2) time are proposed. The first reduces the idle time of a machine while the second, which is known as the smallest process distance rule, minimizes both the machine idle time and the job queue time by computing the distances of all unscheduled jobs. According to numerical experiments, both provide near optimal to optimal solutions with objective cost errors of less than two percent.

We consider a single machine scheduling problem which we studied to improve the efficiency of an automated medical laboratory. In this problem, there are not only chain-structured precedence constraints, but also minimal and maximal times separating successive jobs in the same chain (separation time windows). The criterion to be minimized is the makespan. Potential applications are not restricted to medical analysis. This problem often arises in systems where chemical processes are involved. Therefore the problem studied in this paper is important in practice. We prove that the problem is nonpolynomial (NP)-complete. As a consequence, we propose three heuristics for large size problems and a branch and bound based algorithm for small size problems. Computational results are reported.

A heuristic algorithm for minimizing the makespan or the period to complete a job sequence in flow-shop scheduling problems. The problem, which is represented as n/m/Cmax in the literature, involves the minimization of 'in-process inventory for a given value of the makespan.' This objective function, which is correlated to the transportation requirements, is achieved by a path-based algorithm for minimizing the number of pallets for a given makespan.

In this paper we address the performance evaluation and optimization of a strongly connected event graph with random firing times. We proposed an upper bound and a lower bound for the average cycle time of event graphs knowing the initial marking. We then prove that, under some weak conditions on the firing time distributions, it is possible to reach, on average, a cycle time smaller than any given value [C.sup.*] with a finite marking, assuming that [C.sup.*] is greater than the greatest firing time. Finally, we propose a heuristic algorithm to reach such an average cycle time while minimizing a p-invariant criterion.

Byline: Jean-Marie Proth In this paper, we describe the main characteristics of Supply Chains (SC) and the activities that take place at the strategic and tactical levels. We mention the risks that are specific to SC and show how to measure the performances of an SC at both the strategic and the tactical levels. We also present real-time assignment approaches that are central to control production cycle and Work-In-Process (WIP) level. These methods establish the link between production cycle and WIP level and may be the starting point of a simple evaluation approach of the SC.

This paper presents a low-complexity algorithm for on-line job scheduling at workcenters along a given route in a manufacturing system. At each workcenter, the job has to be processed by any one of a given set of identical machines. Each machine has a preset schedule of operations, leaving out time-windows during which the job's processing must be scheduled. The manufacturing system has no internal buffers and the job cannot wait between two consecutive operations. There is some flexibility in the job's processing times, which must be confined to given time intervals. The scheduling algorithm minimizes the job's completion time, and it is executable in real time whenever the job requirement is generated. Index Terms--No-wait manufacturing, on-line scheduling, time windows.

The 19th Triennial Conference of the International Federation of Operational Research Societies will be held July 10-15, 2011 in Melbourne, Australia. The theme of the conference is: 'World O.R.: Global [...]

Byline: Jean-Marie Proth (1) Author Affiliation: (1) Metz, France Article History: Registration Date: 09/09/2004