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Seminar Series

Each semester the Department of Industrial Engineering hosts a seminar series to educate our students, faculty, alumni, and partners. The department invites guest presenters from prominent industrial engineering programs as well as features the research of our own faculty and students.

Seminar Series - Fall 2015

Industrial Engineering Distinguished Leader Seminar Series

Date  Time Location Speaker
October 9 1:25pm - 2:15pm Freeman Auditorium Edwin Romeijn
H. Milton and Carolyn J. Stewart School Chair and Professor
Georgia Institute of Technology

Title: A column generation based approach to treatment plan optimization for Volumetric Modulated Arc Therapy

Abstract: We study the treatment plan optimization problem for Volumetric Modulated Arc Therapy (VMAT). We propose a new column generation based algorithm that takes into account bounds on the gantry speed and dose rate, as well as an upper bound on the rate of change of the gantry speed, in addition to MLC constraints. The algorithm iteratively adds one aperture at each control point along the treatment arc. In each iteration, a restricted problem optimizing intensities at previously selected apertures is solved, and its solution is used to formulate a pricing problem, which selects an aperture at another control point that is compatible with previously selected apertures and leads to the largest rate of improvement in the objective function value of the restricted problem. Once a complete set of apertures is obtained, their intensities are optimized and the gantry speeds and dose rates are adjusted to minimize treatment time while satisfying all machine restrictions. Comparisons of treatment plans obtained by our algorithm to idealized IMRT plans of 177 beams on 5 clinical prostate cancer cases demonstrate similar quality with respect to clinical dose-volume criteria. For all cases our algorithm yields treatment plans that can be delivered in around 2 minutes. Implementation on Graphics Processing Unit (GPU) allows for solution times that enable clinical implementation in an adaptive treatment planning setting. View Full Abstract & Bio »

November 16 1:25pm - 2:15pm Freeman Auditorium G. Don Taylor
Charles O. Gordon Professor and Department Head
Grado Department of Industrial and Systems Engineering
Virginia Tech

Title: Emerging and Continuing Trends in Worldwide Logistics

Abstract: The field of logistics affects all aspects of modern life.  Annual expenditures on transportation and inventory alone accounts for approximately 8.2 of the gross domestic product of the United States and an even larger percentage in many other countries.  In spite of the magnitude of modern logistics problems, the field of global supply chain logistics is changing rapidly, and the recent recession has increased the pace of change in unanticipated ways.  Five major trends that are expected to continue to shape global logistics in the coming decade will be discussed; the U.S. reliance on imported consumer goods and the emergence of China as the world's manufacturer, the availability and price of energy, the continuing rise of the internet, growing environmental concerns, and increasing governmental debt.  After establishing the significance of these trends, attention will be turned to the great logistics challenges that we now face, and discussion will focus on the need for innovation in niche areas, the need for efficiency gains in general, and the need to think big. View Full Abstract & Bio »

Industrial Engineering Technical Innovation Seminar Series

Date Time Location Speaker
November 20 1:25pm - 2:15pm Freeman Auditorium Harsha Gangammanavar
Postdoctoral Fellow
Department of Industrial Engineering
Clemson University

Title: Sampling-based Stochastic Programming Algorithms for Power Systems Applications

Abstract: In this talk we will present a class of sampling-based stochastic programming (SP) algorithms that do not rely on a-priori characterization of uncertainty through scenarios or distributions. These algorithms can be used directly with data streams generated using state-of-the-art simulators. In the first part of the talk, we will present an algorithm for two-stage SP setups and its application to the sub-hourly economic dispatch problem. Computational results will compare our stochastic approach to deterministic point-forecast method, which is the ongoing practice. In the second part of the talk, we will describe a dynamic extension of our sampling-based algorithm to multistage setups. We will mention the traditional sequential decision approaches like stochastic dual dynamic programming, and showcase the distinguishing features of our algorithm. We will provide asymptotic convergence results, and methods to extract policies in a data-driven manner. Computational experiments involving control of distributed storage devices in power systems will also be presented. Finally, we will discuss ongoing research initiatives in this area and some new applications. View Full Abstract & Bio »

December 4

1:25pm - 2:15pm Freeman Auditorium Merve Bodur
Postdoctoral Researcher
Department of Industrial and Systems Engineering
Georgia Tech

Title: Improved Decomposition Algorithms for Two-Stage Stochastic Integer Programs

Abstract: Many practical planning, design and operational problems involve making decisions under uncertainty. Also, most of them include some integer decisions. Stochastic programming is a useful tool for dealing with uncertainty and integrality requirements in optimization problems. We consider two-stage stochastic integer programs, where the decision maker must take some (integer) decisions before the uncertainty is revealed, then can observe the realizations and take recourse actions.

These problems yield to large-scale mixed integer programs, which are computationally very challenging, thus decomposition methods are used. The most common solution approach is Benders decomposition. However, standard Benders decomposition algorithm usually fails due to the weakness of the linear programming relaxations. We propose two methods to strengthen Benders decomposition algorithm with integrality-based cuts. We present numerical results on integrated service system staffing and scheduling, capacitated facility location and network interdiction problems that demonstrate the computational efficiency of the proposed approaches.  View Full Abstract & Bio »