The robust single machine scheduling problem with uncertain release and processing times

In this work, we study the single machine scheduling problem with uncertain release times and processing times of jobs. We adopt a robust scheduling approach, in which the measure of robustness to be minimized for a given sequence of jobs is the worst-case objective function value from the set of all possible realizations of release and processing times. The objective function value is the total flow time of all jobs. We discuss some important properties of robust schedules for zero and non-zero release times, and illustrate the added complexity in robust scheduling given non-zero release times. We propose heuristics based on variable neighborhood search and iterated local search to solve the problem and generate robust schedules. The algorithms are tested and their solution performance is compared with optimal solutions or lower bounds through numerical experiments based on synthetic data

Evaluation of an expanded satellite based mobile communications tracking system

Since the terrorist events in the United States on September 11, 2001, the Federal Motor Carrier Safety Administration has been testing and evaluating cargo tracking technologies to improve the safety, security, and efficiency of commercial motor vehicle operations. While satellite-based systems used for tracking vehicles and cargo provide sufficient geographic coverage in the majority of the United States, there remain several vital regions that are uncovered and difficult to monitor. One such region is Alaska, where officials arc particularly concerned with the hazardous materials shipments that are transported parallel to the Trans-Alaska Pipeline. This article analyzes the risks and benefits associated with adopting an Expanded Satellite-Based Mobile Communications Tracking System to monitor hazardous materials and high-value cargo in Alaska. Technical and acceptance risks are evaluated against the communication, safety, security and real time information benefits that the system provides. The findings indicate that the system provides a significant communications upgrade relative to previously available technology

NEESR-GC: Seismic risk mitigation for port systems

Issued as final reportNational Science Foundation (U.S.

Planning local container drayage operations given a port access appointment system

This paper studies the management of a fleet of trucks providing container pickup and delivery service (drayage) to a port with an appointment-based access control system. Responding to growing access congestion and its resultant impacts, many US port terminals have implemented appointment systems, but little is known about the potential impact of such systems on drayage fleet efficiency. To address this knowledge gap, we develop a drayage operations planning approach based on an integer programming heuristic that explicitly models a port access control system. The approach determines pickup and delivery sequences for daily drayage operations with minimum transportation cost. We use the framework to develop an understanding of the potential productivity impacts of access control systems on drayage firms. Most importantly, we find that it is critical for terminal operators to provide enough access capacity for drayage, since vehicle productivity can be increased by 10-24% when total access capacity is increased by 30%. Furthermore, poor (but not unreasonable) selection of access appointment time slots by drayage firms may result in substantial customer service deficiencies, reducing the number of customers that can be served by up to 4% for a fixed level of total access capacity.Drayage Pickup and delivery