different manufacturing enterprises use regularly scheduling algorithms in order to help meeting demands over time and reducing operational costs. nowadays, for a better useofresources and manufacturingin accordance withcustomer needs and given the level ofcompetitionbetweencompanies, employing asuitablescheduling programhasa double importance. conventional productionmethods are constantly subs...

In this paper we describe a two-stage optimization model for determining robust rolling stock circulations for passenger trains. Here robustness means that the rolling stock circulations can better deal with large disruptions of the railway system. The two-stage optimization model is formulated as a large Mixed-Integer Linear Programming model. We first use Benders decomposition to determine op...

A hyper-heuristic often represents a heuristic search method that operates over a space of heuristic rules. It can be thought of as a high level searchmethodology to choose lower level heuristics. Nearly 200 papers on hyper-heuristics have recently appeared in the literature. A common theme in this body of literature is an attempt to solve the problems in hand in the following way: at each deci...

This paper presents a hyper-heuristic approach which hybridises lowlevel heuristics to improve constructed timetables. The constructed timetable is analysed and the exams causing a soft-constraint violation are identified. It is observed that both the type of move performed and the order in which exams are rescheduled in the timetable affect the quality of the solution produced. After testing d...

We study the strategic problem of locating tugboats along Norwegian coast to optimize maritime preparedness. The is formulated as a two-stage stochastic program. In first stage, we locate such that nominal coverage requirements are satisfied, whereas deploy located in second stage order assist vessels distress. objective minimize sum costs publicly operated emergency towing service and expected...

This paper considers a three-stage assembly flowshop scheduling problem with sequence-dependent setup < /div> times at the first stage and blocking times between each stage in such a way that the weighted mean completion time and makespan are minimized. Obtaining an optimal solution for this type of complex, large-sized problem in reasonable computational time using traditiona...

The paper considers the 2-stage flow shop problem with parallel dedicated machines. In such a situation, each job can only be processed on a pre specified subset of machines. A mathematical model for this problem is proposed to minimize the maximum completion time among all jobs commonly known as the makespan or the Cmax. Furthermore, two approximate methods are proposed. The first one is a heu...

Traditional optimization techniques such as Dynamic Programming(DP), Linear Programming(LP), and MixedInteger Programming(MIP) have been used to solve complex optimization problems in many diverse fields. Shortcomings of these classical techniques and the rapid development of affordable, powerful computing technology have led to the creation of new classes of heuristic-based optimizing techniqu...

This paper studies a periodic-review, serial inventory system in which echelon r nQ T policies are implemented. Under such a policy, each stage reviews its inventory in every T period and orders according to an echelon r nQ policy. Two types of fixed costs are considered: one is associated with each order batch Q, and the other is incurred for each inventory review. The objective is to find the...