Technical Sessions – Monday July 11

TC-17 IFORS 2011 - Melbourne
1 - Hybrid Simulation Models for Healthcare
Israel Vieira, School of Mathematics, Cardiff University,
Senghennydd Road, CF24 4AG, Cardiff, United Kingdom,
itvieira@hotmail.com
Healthcare systems are embedded into the community they serve, they integrate
a large network of service providers and exhibit dynamic, detailed and
behavioural complexity. Effective and sustainable decision making in healthcare
requires tools that can encompass complexity, handle variability and foresee
the consequences of actions. In this talk we evaluated the extent to which
hybrid models can capture the dynamics of complex healthcare systems, review
existing tools supporting the development of multi-method models, and define
best practice for combining methodologies into one model.
2 - The Case for Combining: Developing Designs for Integrating
System Dynamics (SD) and Discrete Event Simulation
(DES) in Healthcare
Jennifer Morgan, Management Science, University of
Strathclyde, Graham Hills Building, 40 George St, G1 1QE,
Glasgow, United Kingdom, jennifer.s.morgan@strath.ac.uk
SD and DES have been extensively applied to a range of situations in many
ways, and can provide complementary insights into a system. This research
considers the value of combining these approaches and presents proposals for
their integration within healthcare. Designs for linking and a framework for
undertaking mixed modelling interventions are proposed, providing a toolkit
of interaction options. The impact of applying this framework and designs to
facilitate integration in practice is considered. Models developed with an oncology
unit are discussed and proposed practices are reflected upon.
3 - Assessing the Effectiveness of Infection Control Policies
for MRSA in Different Hospital Settings using a
Multiscale Modelling Framework
Rosemarie Sadsad, University of New South Wales, Centre for
Health Informatics, 2052, Sydney, New South Wales, Australia,
r.sadsad@student.unsw.edu.au
Infection control policies have mixed results for MRSA due to differences in
context. A range of policies were simulated to study their impact on MRSA for
different hospital settings. The model is based on a multiscale modelling framework
and validated with two Australian hospitals. The incidence of MRSA
was different across ward types and bed locations. The prevalence of MRSA
responded to hand washing policies only. The incidence of MRSA responded
to hand washing, staffing and cohorting policies. Models that consider context
help identify appropriate hospital policies for particular settings.
4 - Decision Support in Pre-hospital Stroke Care Operations:
Improving Eligibility of Acute Stroke Patients for
Thrombolysis Treatment with Simulation
Leonid Churilov, The University of Melbourne, Neurosciences
Bld, 300 Waterdale Rd, Austin Health, Repat Campus, 3083,
Heidelberg Heights, VIC, Australia,
leonid.churilov@gmail.com, Andrew Flitman, Helen Dewey
There is a need for a solution capable of simultaneous systemic evaluation of
multi-factorial interventions in pre-hospital acute care systems aimed at increasing
patients’ eligibility for stroke thrombolysis. We propose an OR solution
in the form of a simulation model that provides clear measure of the
relative benefit of alternative potential interventions, thus demonstrating how
OR modelling can be used for providing decision support in pre-hospital stroke
care operations.
� TC-17
Tuesday, 15:00-16:30
Meeting Room 214
Network Optimisation
Stream: Network Optimisation and Telecommunications
Invited session
Chair: Francisco Saldanha-da-Gama, CIO/DEIO, University of
Lisbon, FCUL-DEIO, Bloco C6, Piso 4, 1749-016, Lisbon, Portugal,
fsgama@fc.ul.pt
1 - A Flow-dependent Quadratic Steiner Tree Problem in
the Euclidean Plane
Charl Ras, Department of Electrical and Electronic Engineering,
University of Melbourne, Grattan Street, 3010, Parkville,
56
Victoria, Australia, cjras@unimelb.edu.au, Doreen Thomas,
Marcus Brazil
We introduce a flow-dependent version of the quadratic Steiner tree problem.
An instance of the problem on a set of sources and a sink asks for a directed
tree spanning these nodes and a bounded number of Steiner points, such that
the sum of products of the edge-flows and the squares of the edge-lengths is a
minimum. Our motivation for studying this problem is as a model for relayaugmentation
of wireless sensor networks. We prove geometric results on the
structure of optimal and locally optimal solution-trees and describe a geometric
linear-time algorithm for fixed-topology construction.
2 - Dual Decomposition for Computational Optimization
of Minimum-Power Shared Broadcast Tree in Wireless
Networks
Di Yuan, Department of Science and Technology, Linköping
University, SE 601 74, Norrköping, Sweden, diyua@itn.liu.se,
Dag Haugland
We consider the problem of constructing a minimum-power shared broadcast
tree (SBT) in wireless communication networks. We approach SBT using dual
decomposition method applied to an integer linear programming formulation.
As a feature of the formulation, the relation between some of the variables is
preferably formulated implicitly. The decomposition scheme is coupled with a
fast local search algorithm. We report computational results demonstrating the
effectiveness of the proposed approach. In average, the optimality gap is less
than three percent.
3 - Models and Algorithms for N-k Survivable Network Design
Richard Chen, Quantitative Modeling and Analysis, Sandia
National Laboratories, P.O. Box 969 MS 9155, 3806 Picard Ave.,
94551, Pleasanton, CA, United States, rlchen@sandia.gov
We present general bilevel and trilevel optimization models to identify vulnerabilities
in a network and plan expansion and defensive measures. We describe
a new decomposition-separation algorithm for finding an optimal solution to
the trilevel model. We illustrate the applicability of trilevel optimization to the
N-k problem in power system design. Given a power system represented by a
network with equations governing power flow, power generation and consumption,
how do you optimally enhance the system to survive the simultaneous
failure of k or fewer components?
4 - Hub Location Problems with Multiple Flow Categories
Francisco Saldanha-da-Gama, CIO/DEIO, University of Lisbon,
FCUL-DEIO, Bloco C6, Piso 4, 1749-016, Lisbon, Portugal,
fsgama@fc.ul.pt, Isabel Correia, Stefan Nickel
In this paper, a unified modeling framework is proposed for capacitated hub
location problems with multiple flow categories. At most one hub (dedicated
or not) can be located in each node. The capacity constraints refer to the nonprocessed
incoming flow to the hubs. The framework includes several situations
of practical interest. A mixed-integer linear programming formulation
enhanced with several sets of additional inequalities is proposed as well as a
reformulation yielding tighter lower bounds. A computational analysis is presented
using data derived from the well-known AP data set.
� TC-18
Tuesday, 15:00-16:30
Meeting Room 215
Applications of DEA
Stream: Data Envelopment Analysis
Invited session
Chair: Arash Aliakbari, Parto Novin Modiriat Iranian (Penco
Consulting Group ), Flat 4, No 22 , Unit 22 Separ St, Africa Blvd.,
Tehran, Iran, Islamic Republic Of, arashaliakbari@yahoo.com
1 - DEA Applications of Human Capital Investment to
Achieve Knowledge-Based Economy in ASEAN5
Elsadig Ahmed, Faculty of Business and Law, Multimedia
University, 75450, Melaka, Malaysia, elsadigmusa@yahoo.com