2016 INFORMS Annual Meeting Program

WB26

INFORMS Nashville – 2016

WB24

2 - An Optimization Framework For Simultaneous Space Logistics Mission Planning And Spacecraft Design Hao Chen, University of Illinois at Urbana-Champaign, 310 E. Springfield Ave, Champaign, IL, 61820, United States, hchen132@illinois.edu, Koki Ho This paper proposes a network modeling and optimization method for human space exploration campaign-level mission planning. The interplanetary space is discretized into nodes and the space missions are modeled as generalized multi- commodity network flows, where payload, propellant, and spacecraft are considered as separate commodities. This problem results in a mixed-integer nonlinear programming, and we solve this problem with branch-and-bound and gradient-based method (e.g., SQP). The proposed framework enables us to optimize the space mission and its spacecraft design concurrently at a mid-fidelity.

109-MCC Optimization in Radiation Therapy Sponsored: Health Applications Sponsored Session Chair: Omid Nohadani, Northwestern University, 2145 Sheridan Road, Room M233, Evanston, IL, 60208-3119, United States, nohadani@northwestern.edu 1 - Designing Radiation Therapy Criteria With Data-driven Robust Optimization S. Nastaran Shojaei, Northwestern University, 2145 Sheridan Road Room C210, Evanston, IL, 60208, United States, nastaranshojaei@u.northwestern.edu, Seyed M.R. Iravani, Omid Nohadani Radiation therapy planning is an iterative process of optimization and evaluation, making it both time consuming and not reproducible. Often feasibility is not attainable for which planners relax some of the criteria. We present a data-driven robust optimization approach that can provide a new and less sensitive set of criteria which warrant high quality plans despite some constraint violations within a realistic range. A large set of clinical data is used to inform the method. 2 - Multicriteria Optimization For Brachytherapy Treatment Planning Victor Wu, University of Michigan, vwwu@umich.edu, Marina Epelman, Michael Herman, Kalyan Pasupathy, Mustafa Sir, Christopher Duefel High Dose Rate Brachytherapy (HDR-BT) has become a popular mode of radiation therapy for its ability to deliver high dose localized to the tumor, resulting in lower risk of side effects. The goal is to allow the physician to explore trade-offs via an intuitive GUI with respect to multiple dose-volume criteria (also known as value-at-risk) among high quality plans. The underlying problem is non-convex and therefore is not practically solvable. The desire to generate plans quickly, i.e., within the 30 minutes while the patient is under anesthesia, motivates solving convex approximations (based on conditional value-at-risk) instead. Our method is retrospectively tested on various cancer sites. 3 - Automated IMRT Treatment Planning For SBRT Paraspinal Case Using Prioritized Optimization Masoud Zarepisheh, Assistant professor/attending, Memorial Sloan Treatment planning is a patient specific and time consuming task, with plan quality heavily dependent on planners’ skills. In this study, we are employing prioritized optimization (PO) to automate the planning process. PO is a step-wise technique where the highest priority goal (e.g., tumor coverage) is optimized first. At each iteration step the previous objectives are turned into constraints and a new goal is optimized. We integrate our optimization package with the commercial treatment planning system called Eclipse. 4 - Time-dependent Radiation Therapy Optimization Arkajyoti Roy, Bowling Green State University, 4154 Moser Ln, Bowling Green, OH, 43551, United States, aroy@bgsu.edu, Omid Nohadani Low oxygen concentration reduces the radio-sensitivity of cells. Re-oxygenation leads to temporal changes during treatment. However, the re-oxygenation trajectory is unpredictable, leading to uncertain radio-sensitivity. We develop a time-dependent uncertainty set that models the evolution of radio-sensitivity. To reduce over conservativeness at later time-periods, a two-stage robust optimization approach is proposed that can incorporate such uncertainties. For a clinical prostate cancer case, the robust method is compared to current clinical methods. WB25 110A-MCC Logistics II Contributed Session 1 - Coordination Between Shipper And Carrier In City Logistics Gitae Kim, Hanbat National University, Dept. of Industrial Management Engineering, School of Engineering, Daejeon, 34158, Korea, Republic of, gitaekim@hanbat.ac.kr, Juncheul Park In a decentralized system in city logistics, two stakeholders such as shipper and carrier have different their own objectives. Coordination is necessary to obtain the win-win strategy for two parties. This paper investigates contract models between a shipper and a carrier to achieve the coordination in city logistics. Quantity flexibility (number of transportation services) and revenue sharing contract types are formulated by stochastic programming model using options. From the experimental results, we find the efficient frontier for two stakeholders. Kettering Cancer Center, New York, NY, United States, zarepism@mskcc.org, Linda Hong, James Mechalakos, Margie Hunt, Gikas Mageras, Joseph Deasy

WB26 110B-MCC Information Systems I Contributed Session

1 - Designing Referral Policies For Optimal Membership Growth: A Real World Randomized Experiment In An Exclusive Online Dating Site Rodrigo Belo, Assistant Professor, Erasmus University, Mandeville Building T09-20, Burgemeester Oudlaan 50, Rotterdam, 3062 PA Rotterdam, Netherlands, rbelo@rsm.nl, Ting Li We use data from a real-world randomized experiment in an exclusive online dating site to study the effect of member-get-member referral policies on membership growth and online user activity. We find that stricter policies, i.e., policies that require members to invite more friends so that they can continue using the service for free, are more effective at fostering growth in multiple dimensions, including invitations, online user activity, and paid memberships. We discuss the mechanisms that may be at play and implications for business. 2 - Agent Based Simulation For Social Support Networks M. Gisela Bardossy, University of Baltimore, 1420 N. Charles Street, Baltimore, MD, 21201, United States, mbardossy@ubalt.edu, Stefano Za, Eusebio Scornavacca Support networks have benefited from digital and networking tools. In an interconnected world, people depend on each other to achieve their personal and group goals. We model this inter dependency using agent based simulation and test various hypothesis regarding rules of engagement, dissipation of information in the network, discrepancy between reality and beliefs and the updating and correction of beliefs. This information can inform the design of social platforms as the implications of choice characteristics are better understood. Some preliminary results are analyzed and discussed. 3 - Multi-homing Within Platform Ecosystems: The Strategic Role Of Human Capital Vijayaraghavan Venkataraman, Georgia Institute of Technology, 800 West Peachtree NW, Atlanta, GA, 30308, United States, vijayaraghavan.venkataraman@scheller.gatech.edu, Marco Ceccagnoli, Chris Forman Even though there has been considerable research on platform ecosystems, prior literature has focused mostly on the platform owners and their strategies. In this paper, I look at the complementor firms, instead, and try to understand why the incidence of multi-homing, a strategy in which a complementor firm chooses to join multiple platforms rather than one, is often quite low. I build a capability framework based on human capital and test it on micro-level data from the ERP platform ecosystem. The study has important implications for our understanding of platform growth and innovation and contributes toward the literature on platform ecosystems as well as strategic human capital. 4 - The Impact Of Sharing Markets On Product Durability Maryam Razeghian, Ecole Polytechnique Federale de Lausanne, This paper studies the effects of sharing markets on the prices for new products and on product design in terms of durability. In a dynamic economy with overlapping generations, consumers take strategic purchasing decisions, anticipated by a durable-goods monopolist. Without sharing, the optimal durability increases in the production cost. In the presence of sharing, the firm prefers to limit durability for low-cost products, effectively disabling a secondary sharing market. However, all else equal, a peer-to-peer economy never decreases the incentives to provide durability. ODY 4.16, Station 5, Lausanne, 1015, Switzerland, maryam.razeghian@epfl.ch, Thomas A. Weber

403