Ghaith Rabadi | Old Dominion University (original) (raw)

Papers by Ghaith Rabadi

Procedia Computer Science, 2013

World trade has been increasing dramatically in the past two decades, and as a result containers ... more World trade has been increasing dramatically in the past two decades, and as a result containers exchange has grown significantly. Accordingly, container terminals are expanding to meet this increase and new container ports have opened. Ports with one or more container terminals are considered complex systems in which many resources, entities and transporters interact to achieve the objective of safely moving containers delivered by ships inland as well as loading containers delivered by trucks and rail onto ships. Ports with multimodal transportation systems are in particular complex as they typically operate with ships arriving to one or more terminals, multiple quay cranes, rubber tyred gantry cranes, trains, and trucks delivering containers of different types to terminals.

With several resources of different types working and interacting, the system can be so complex that it is not easy to predict the behavior of the system and its performance metrics without the use of simulation. In this paper, a generic discrete-event simulation that models port operations with different resource types including security gates, space, rubber tyred gantry cranes, trains, quay cranes, and arriving and departing ships, trucks, and trains is presented. The analysis will entail studying various scenarios motivated by changes in different inputs to measure their impact on the outputs that include throughput, resource utilization and waiting times.

Procedia Computer Science, 2015

The International Journal of Advanced Manufacturing Technology, 2007

This paper addresses the single machine early/ tardy problem with unrestricted common due date an... more This paper addresses the single machine early/ tardy problem with unrestricted common due date and sequence-dependent setup times. Two algorithms are introduced to reach near-optimum solutions: the SAPT, a heuristic tailored for the problem, and a simulated annealing (SA) algorithm. It will be shown that SA provides solutions with slightly better quality; however, SAPT requires much less computational time. SAPT-SA is a hybrid heuristic that combines both approaches to obtain high quality solutions with low computational cost. Solutions provided by the three algorithms were compared to optimal solutions for problems with up to 25 jobs and to each other for larger problems.

Society for computer …, 2000

In this paper, a Branch-and-Bound (B&B) algorithm is presented to solve the problem of minimizing... more In this paper, a Branch-and-Bound (B&B) algorithm is presented to solve the problem of minimizing the maximum completion time C max on unrelated parallel machines with machine eligibility restrictions when job preemption is not allowed. A customized lower bound, a search and a branching strategy are developed for the B&B. A machine eligibility factor is also introduced to represent the percentage of jobs eligible across all machines. Multiple instances of the problem with different machine, job, and eligibility factor configurations are generated and solved. The B&B algorithm is able to solve up to 8 machines and 40 jobs within a reasonable time. To evaluate the performance of the B&B algorithm, the number of nodes examined is used as a measure of performance. It was established through experimentation that the B&B algorithm's performance increased with increasing eligibility factor.

International Series in Operations Research & Management Science, 2016

In a Just-In-Time (JIT) environment, it is desired to complete the jobs as close as possible to t... more In a Just-In-Time (JIT) environment, it is desired to complete the jobs as close as possible to their due dates. It is obvious that missing a job's due date may result in the loss of a customer, or the need to compensate the customer for the delay in meeting the due date. On the other hand, producing a job much earlier than its due date may result in an increase in holding (inventory) cost or deterioration of products. In this paper, a singlemachine problem is considered. Both earliness and tardiness are minimized when all jobs have a large common due date, penalties for earliness and tardiness are equal, and machine setup time is sequence-dependent. A Branch-and-Bound algorithm to find optimal solutions for the problem is introduced. Extensive computational experience in this paper shows that optimal solutions for problems with up to 25 jobs are obtained within a reasonable time.

—Mega sports events such as the Olympics and the FIFA World Cup are highly attended and countries... more —Mega sports events such as the Olympics and the FIFA World Cup are highly attended and countries compete ferociously to host such events due to their perceived long term positive effects. Inbound tourist forecasting is an important aspect of the hosting decision; however, due to the infrequent occurrence of such events, it is not straightforward to predict the number of tourists who may travel to the host country. We focus in this paper on a regression model known as the Gravity Model to predict the number of inbound tourists between pairs of countries and we extend it to include new predictors and study their impact.

Andres Sousa-Poza, Old Dominion University manufacturing. Choosing the "best" inventory managemen... more Andres Sousa-Poza, Old Dominion University manufacturing. Choosing the "best" inventory management system depends on numerous parameters, among the most important of which are supply chain-related parameters, such as the demand pattern, the demand level, and the inventory costs. In this article, we present a methodology of how to carry out a comparison between these two inventory management systems in order to select the better one.

Abstract¾In this paper we propose a tabu search implementation to solve the unrelated parallel ma... more Abstract¾In this paper we propose a tabu search implementation to solve the unrelated parallel machines scheduling problem with sequence-and machine-dependent setup times to minimize the schedule's makespan. The problem is NP-hard and finding an optimal solution efficiently is unlikely. Therefore, heuristic techniques are more appropriate to find near-optimal solutions. The proposed tabu search algorithm uses two phases of perturbation schemes: the intra-machine perturbation, which optimizes the sequence of jobs on the machines, and the inter-machine perturbation, which balances the assignment of the jobs to the machines. We compare the proposed algorithm to an existing one that addressed the same problem. The computational results show that the proposed tabu search procedure generally outperforms the existing heuristic for small-and large-sized problems.

Proceedings of the 5th Biannual World Automation Congress, 2002

... Acknowledgements The funding for this project was provided through the Space Act Agreement be... more ... Acknowledgements The funding for this project was provided through the Space Act Agreement between NASA/KSC and the University of Central ... 4. Nayani, N., and Mollaghasemi, M., 1998, Validation and Verification of the Simulation Model of a Photolithography Process in ...

Engineering Management Journal, 2006

Engineering Management Journal, 2003

International Journal of Operational Research, 2014

Organization, Operation, and Evolution, 2014