2016-2018 Operations Research Seminar

Welcome to the Web page of the SFU Operations Research Seminar Series. We are associated with:
CORDS (Centre for Operations Research and Decision Sciences), and
The Department of Mathematics, Simon Fraser University.
Our aim is to meet and discuss Operations Research topics.

Unless noted the talks will be at 2:30 on Thursday in Room 2746, SFU Surrey.
Please contact Tamon Stephen if you would like to speak.

Date Speaker Title and Abstract
Dec. 11th

*Monday*

*9:00-10:30*

*SUR 2710*
Bolong He

M.Sc. project presentation

Senior Supervisor: T. Stephen
Analysis of Firefighter Absences and Hiring Schedule Optimization at the Surrey Fire Department

Abstract:
We study staffing issues at the Surrey Fire Department with a view to understanding and optimizing the annual hiring cycle for full-time firefighters. This project begins with a discussion of a previous model used by the Fire Department which predicts absences based on seasonally adjusted historical data and then optimizes the hiring cycle based on a simulation. We extend the analysis of the data to include the age cohort as a variable and compare short-term and long-term absences. We then use time series to predict future absences and use these predictions along with additional constraints to optimize the hiring schedule.
Dec. 4th

*Monday*

*10:30-1:00*

*SUR 3040*
Timothy Yusun

Ph.D. thesis defence

Senior Supervisor: T. Stephen
On the Circuit Diameters of Polyhedra

Abstract:
we develop a framework to study the circuit diameters of polyhedra. The circuit diameter is a generalization of the combinatorial (edge) diameter, where walks are permitted to enter the interior of the polyhedron as long as steps are parallel to its circuit directions. Because the circuit diameter is dependent on the specific realization of the polyhedron, many of the techniques used in the edge case do not transfer easily. We reformulate circuit analogues of the Hirsch conjecture, the d-step conjecture, and the nonrevisiting conjecture, recovering the edge case equivalences in the circuit case. To do this we adapt the notion of simplicity to work with circuit diameter, and so we define C-simplicity and wedge-simplicity. Then, we prove the circuit 4-step conjecture, including for unbounded polyhedra, by showing that the original counterexample U4 to the combinatorial analogue satisfies the Hirsch bound in the circuit case, independent of its realization. This was the first known counterexample to Hirsch, and several families of counterexamples are constructed from U4. In particular, the unbounded Hirsch conjecture could still hold in the circuit case. We also use computational methods to study Q4, the bounded counterpart to U4, and give two realizations with different circuit diameters. It remains open whether Q4 is circuit Hirsch-sharp; however, we are able to lower the distance bound for at least one direction between the two far vertices of Q4. Finally, we present some auxiliary results involving representations of polyhedra and circuit calculations.
Oct. 26th

via COCANA (Kelowna)

Hamid Afshari

University of Manitoba and UBC Okanagan
Improving the Resilience of Energy Flow Exchanges in Eco-Industrial Parks: Optimization Under Uncertainty

Further details available from the COCANA Website.
Sept. 28th

via COCANA (Kelowna)

Gord Lovegrove

UBC Okanagan
Models of Bicycle Rider Perceptions Related to Safety and Comfort

Further details available from the COCANA Website.
Sept. 16th

*Saturday, 8:30-4:00*

*2740*
WCOM

Details of the Fall 2017 West Coast Optimization Meeting here.
Sept. 14th

via COCANA (Kelowna)

Scott Lindstrom

University of Newcastle (Australia)
Douglas-Rachford Method for Non-Convex Feasibility Problems

Further details available from the COCANA Website.


Archives of the 2006-07, 2007-08, 2008-09, 2009-10, 2010-11, 2011-12, 2013-14, 2014-15, 2015-16 and 2016-17 SFU Operations Research Seminars.

Last modified September 12th, 2017.