|
Infrastructure systems and supply chains are at the basis of societal functions and reach into every aspect of modern life. Examples of these vital systems include goods and service distribution networks, emergency services, financial services, transportation and telecommunication networks, electrical power grids and water supply systems among others. Unfortunately, recent world events have demonstrated that even the strongest supply chains or infrastructure systems can be extremely vulnerable to unforeseen events. The World Trade Centre terrorist attack in 2001, the Tsunami in December 2004, and hurricanes Katrina and Rita, which hit the US gulf coast in 2005, are only the most dramatic evidence of the precariousness and vulnerability of our critical infrastructure to natural disasters and terrorist attacks. Other less catastrophic but more frequent incidents, such as plant fires, industrial accidents, labor strikes and power outages, can also have costly and, sometimes, harmful implications, especially if the incapacitated or destroyed supply line provides essential services or goods (e.g., hospitals, drugs, vaccines).In view of all these risks and hazards, there has been a heightened awareness and concern over the past few years for increasing the security and reliability of infrastructure and supply systems that may be subject to potential external disruptions. Planning against possible disruptive acts of nature or terrorism is an enormous financial and logistical challenge, especially if one considers the scale and complexity of today's logistic systems, the increasing interdependence among numerous system elements, the variety of threats and hazards, and the prohibitive costs involved in securing large numbers of system components. Since it is generally impossible to secure all assets, it is important to devise systematic approaches for identifying critical elements, optimize the protection of key system components and even build new systems which are inherently robust. Optimization techniques can play a significant role in this respect.Over the last few years, a few optimization models have been developed for identifying supply chain configurations that are both reliable with respect to disruptions and economically cost-effective in terms of infrastructure investment (design models). Additionally, new models have been proposed recently which can be used to improve the reliability of infrastructure systems that are already in place and for which a complete reconfiguration would be too costly (protection models).The overall objective of this project is to develop a suite of new optimization models in both of these reliability-related research areas. In particular, new modeling approaches will be developed to overcome some of the overly simplified assumptions which characterize existing models, to capture additional complex issues arising in systems reliability planning, and to reflect the diversity of possible application settings. As an example, future modeling efforts should aim at incorporating various combinations of the following issues: (1) different operational protocols of the systems (cost-based vs. standards-based supply models); (2) different types of hazards (expected models for natural disasters vs. worst-case models for premeditated attacks); (3) different underlying models (facility location, network, multi-echelon supply models); (4) stochastic aspects such as random numbers of possible losses and component-specific failure probabilities; (5) different degrees of facility protection (protected components may be completely immune to attacks and failures, have a lower probability of being disrupted, or preserve part of their operational capabilities depending on the level of protection investment); (6) multiple objectives (operational costs, lost-sales cost, system efficiency, coverage, risk level). Both exact and heuristic techniques will also be developed to solve the newly proposed models.
|