2016 INFORMS Annual Meeting Program

MA32

INFORMS Nashville – 2016

3 - Policy Uncertainty And Real Options On Switching Of Peak Power Plants

to capturing marine port behaviors with respect to system operational factors. The procedure utilizes a system dynamic simulation model to analyze port operations under unpredictable and fluctuating loads to isolate significant critical port infrastructure components. The resultant critical components will provide a basis for future public policy decision analysis pertaining to marine port resiliency subject to extreme events. 2 - An Optimal Stopping Approach To Portfolio Risk Measurement Kun Zhang, Mr, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, Hong Kong, 000, Hong Kong, kunzhang6-c@my.cityu.edu.hk, Guangwu Liu, Bingfeng Zhang Portfolio risk measurement under the nested setting involving a two-level simulation procedure is a challenging computational problem. To reduce the computational burden, we propose an optimal stopping approach in which only one observation is required in the inner-level simulation for each outer-level scenario. In particular, we show that conditional value-at-risk (CVaR) of a portfolio can be represented as the solution to an appropriately constructed optimal stopping problem. Then the least squares method is employed to solve it, leading to a fast lower bound algorithm for portfolio CVaR. Numerical results show that this approach works well and produces accurate estimates of portfolio CVaR. 3 - A Simulation Model For Assessing Mitigation Strategies Against Cyber Attacks Soumyo D Moitra, Senior Member of Technical Staff, Software Engineering Institute, 5000 Forbes Avenue, Pittsburgh, PA, 15213, United States, smoitra@sei.cmu.edu Defending information networks from cyber attacks is a major concern. We propose a simulation model that helps analyze the risks involved in different defense strategies. The model considers attack categories, vulnerabilities in target hosts and the probabilities of a negative impact as a function of attack categories and host states. The host states are modeled as functions of mitigation strategies. Thus the effectiveness of alternative mitigation strategies can be estimated. An illustrative example is presented and the advantages of this approach are discussed. 4 - Support Points: A New Method For Compacting Distributions Simon Mak, Graduate Student, Georgia Institute of Technology, North Ave NW, Atlanta, GA, 30332, United States, smak6@gatech.edu In this presentation, we introduce a new method for compacting a continuous distribution into a finite set of representative points, which we call support points. These points not only provide theoretical advantages over both Monte-Carlo (MC) and quasi Monte-Carlo (qMC) methods in integration, but can also be computed for any distribution in practice. To generate support points efficiently in high-dimensions, a blockwise coordinate descent algorithm is proposed which exploits closed-form majorization-minimization updates. Simulation studies and a real-world Bayesian example show that support points provide a sizable reduction in integration error compared to MC and qMC methods. 204-MCC Networks in Healthcare Sponsored: Manufacturing & Service Oper Mgmt, Healthcare Operations Sponsored Session Chair: Itai Gurvich, Kellogg School of Management, Evanston, IL, United States, i-gurvich@kellogg.northwestern.edu 1 - Network Effects In Epidemic Propagation Kimon Drakopoulos, Massachusetts Institute of Technology, kimondr@mit.edu In this paper we analyze data on the evolution and propagation of influenza across the United States and discover that compartmental epidemic models enriched with environment dependent terms have fair prediction accuracy, and that the effect of inter-state traveling is negligible compared to the effect of intra- state contacts. 2 - Distance, Quality, Or Relationship? Interhospital Transfer Of Heart Attack Patients Lauren X Lu, Associate Professor, University of North Carolina, Chapel Hill, NC, United States, lauren_lu@unc.edu, Susan F Lu We empirically investigate the pattern of where heart attack patients are transferred between hospitals. Our conditional logit analysis shows that the relationship of being affiliated with the same multihospital system plays a dominant role in the choice of transfer destinations, compared to distance and quality. When using 30-day readmission rate to evaluate the health outcome of transferred patients, we find that relationship-based transfers are associated with a much higher readmission rate than distance-based and quality-based transfers. MA34

Stein-Erik Fleten, Norwegian University of Science and Technology, stein-erik.fleten@iot.ntnu.no, Marius Johansen, Alois Pichler, Carl J Ullrich We examine empirically how economic factors, government policy, and strategic interactions a ffect managers’ decisions to switch between operating and stand-by states for peaking electric power generators. We model the switching decisions using a structural model of a dynamic optimal decision game. We focus on the power markets in the Northeastern United States, where annual observations of such decisions are available. The results indicate that regulatory uncertainty significantly increases firms’ perception of switching costs, and that large power producers are noticeably more influenced by their economic environment in their decision-making than small firms.

MA32 203A-MCC Scheduling V Contributed Session

Chair: Nermine Harraz, Associate Professor, Alexandria University - Faculty of Engineering, Alexandria, Egypt, nharraz@alexu.edu.eg 1 - Two Stage, Single Lot, Lot Streaming Problem For A 1 + M Hybrid Flow Shop Sanchit Singh, Virginia Tech, 1206 University Terrace, Apt F, Blacksburg, VA, 24060, United States, sanchit@vt.edu This paper considers a single lot, lot-streaming problem for a hybrid flow shop consisting of a single machine at Stage 1 and M identical machines at Stage 2. The aim is to find optimal number, sizes and allocation of sublots to the machines at Stage 2 for minimizing make span. An exact algorithm is developed with polynomial time search to obtain an optimal schedule when the sublot sizes are continuous. A branch-and-bound based method is also developed for the case of integer sublot sizes that employs tight bounds. Its performance is tested against the direct solution of the MIP formulation by CPLEX. 2 - Ideal Schedules Kangbok Lee, City University of New York, York College, 94-20 Guy R Brewer Boulevard, Queens, NY, 11451, United States, kangbok.lee3@gmail.com, Joseph Leung, Michael L Pinedo An ideal schedule is referred to as a schedule minimizing both maximum and total completion times simultaneously and an ideal problem is a problem where every instance of the problem has an ideal schedule. We identify the boundary between ideal and non-ideal problems and investigate the algorithms for ideal schedules under different job characteristics such as processing times, release dates, precedence constraints, and eligibility constraints. 3 - An Exact Model For Solving The Hybrid Flow Shop Scheduling Problem Nermine Harraz, Associate Professor, Alexandria University - Faculty of Engineering, Alexandria, Egypt, nharraz@alexu.edu.eg This work presents a model to solve the hybrid Flow Shop Scheduling problem. The developed Mixed Integer Programming model considers optimizing a dual criteria objective function to minimize a convex sum of makespan and the number of tardy jobs under various constraints. The constraints consider unrelated parallel machines, precedence relations, stage skipping, machine eligibility, operations lag time, machine release times, and sequence dependent anticipatory and non-anticipatory setup times. An exact solution is used to solve the model and to implement it in a real world packaging case. The output shows that the model is efficient and applicable easily under different conditions.

MA33 203B-MCC Simulation I Contributed Session

Chair: Simon Mak, Graduate Student, Georgia Institute of Technology, North Ave NW, Atlanta, GA, 30332, United States, smak6@gatech.edu 1 - Dynamic Simulation Of Marine Port Resiliency Henry Lester, University of South Alabama, PO Box 8172, Mobile, AL, 36689, United States, hlester@southalabama.edu, Raymond L Smith Marine port system resiliency indicates the degree a port can resist and recover from a potential disruption. Essential measures of this port resiliency include operational factors subject to excessive burdens. This paper presents an approach

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