Technical Sessions – Monday July 11

TD-09 IFORS 2011 - Melbourne
Iron & steel production can be divided into multiple stages, it is important to
coordinate the production in each stage in order to satisfy the material requirement
for each production line and reduce the total production cost. Then the
supply chain coordinating problem is proposed to determine the supply quantity
and the destination production line for each production line in the preceding
stage. To describe the problem, a mixed integral programming model is formulated.
Then dynamic programming based algorithm is developed to solve the
problem whose efficiency is verified by experiment.
3 - Modelling Unidirectional Transshipments from a Retail
Network to Support a Virtual Store
Thomas Archibald, Business School, University of Edinburgh,
29 Buccleuch Place, EH8 9JS, Edinburgh, United Kingdom,
T.Archibald@ed.ac.uk, Jiaqi Zhang
We consider a multi-location inventory system in which demand at one of the
locations can be met by local stock or by transshipment from any of the other
locations. This situation arises, for example, in a retail company which has a
branch network and a virtual store. Under the assumption of independent continuous
review replenishment with fixed lead time at each location, we model
the system as a semi-Markov decision process. Using decomposition, we develop
an effective heuristic transshipment policy.
� TD-09
Tuesday, 17:00-18:30
Meeting Room 108
VRP II
Stream: Vehicle Routing
Invited session
Chair: Vinícius Armentano, Faculdade de Engenharia Elétrica e de
Computação, Universidade de Campinas, FEEC-UNICAMP, Av.
Albert Einstein 400, 13083-852, Campinas, São Paulo, Brazil,
vinicius@densis.fee.unicamp.br
1 - Estimation of an Activity-based Demand Model as a
Class of Vehicle Routing Problems using Inverse Optimization
Joseph Chow, Institute of Transportation Studies, University of
California, Irvine, 4000 Anteater Instruction and Research Bldg
(AIRB), 92697, Irvine, CA, United States,
joseph.chow@gmail.com, Will Recker
Inverse optimization is used to estimate unknown coefficients of the utility
function of activity-based travel demand models formulated as vehicle routing
problems that are based on a utility maximizing behavioral framework, as well
as for estimating coefficients of multiple objectives based on observed patterns.
The household activity pattern problem is presented as one such model. The
inverse household activity pattern problem with soft time windows is estimated
using a cutting plane algorithm and tested with the 2001 California Household
Travel Survey.
2 - Routing with Multiple Deliverymen
Reinaldo Morabito, Dept. of Production Engineering, Federal
University of São Carlos, CP 676, 13565-905, Sao Carlos, Sao
Paulo, Brazil, morabito@ufscar.br, Vitória Pureza
In real life distribution of goods, relatively long service times may make it
difficult to serve all requests during regular working hours, particularly when
the beginning of the service in each site must occur within a time window,
and violations of routing time restrictions are highly undesirable. We address
this situation with a variant of the vehicle routing problem with time windows
for which a number of extra deliverymen can be assigned to each route. We
present a mathematical programming formulation for the problem and a tabu
search heuristic for obtaining minimum cost routes.
3 - Fleet Deployment Optimization for Tramp Shipping
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Vinícius Armentano, Faculdade de Engenharia Elétrica e de
Computação, Universidade de Campinas, FEEC-UNICAMP, Av.
Albert Einstein 400, 13083-852, Campinas, São Paulo, Brazil,
vinicius@densis.fee.unicamp.br, Rodrigo Branchini
We address a tactical planning problem faced by many tramp shipping companies
that have cargo contracts that they are committed to carry, while trying to
serve optional spot cargoes to increase its revenue over medium-term horizon.
The decisions include the number and type of vessels deployed, the assignment
of vessels to contractual and spot voyages and the determination of vessel
routes and schedules in order to maximize the profit. This problem is modeled
as a mixed integer programming which is solved using COIN-OR open source
platform. Computational results are reported.
� TD-10
Tuesday, 17:00-18:30
Meeting Room 111
Planning Railway Rapid Transit
Stream: Public Transit
Invited session
Chair: Juan A. Mesa, University of Seville, 41092, Sevilla, Spain,
jmesa@us.es
1 - Recovery of Disruptions in Rapid Transit Networks
Luis Cadarso, Matemática Aplicada y Estadística, Universidad
Politécnica de Madrid, Pz. Cardenal Cisneros, 3, 28040, Madrid,
Spain, luis.cadarso@upm.es, Ángel Marín, Gabor Maroti
This paper focuses on disruption management of Rapid Transit Rail Networks;
such networks feature frequent train services and heavy passenger loads. In
current practice, the timetable (TT) and the rolling stock (RS) are rescheduled
sequentially. Here we propose an integrated multiobjective model for TT and
RS recovery to minimize the recovery time, the passenger inconvenience and
the incurred system costs. The model is validated by a simulation tool of the
passenger flows during the disruption. The computations are based on realistic
problem instances of the Spanish rail operator RENFE.
2 - A Path-relinking Algorithm for the Railway Network Design
Problem
Federico Perea, Estadística e Investigación Operativa Aplicadas
y Calidad, Universidad Politécnica de Valencia, 46021, Valencia,
Spain, perea@us.es, Antonio J. Lozano, Juan A. Mesa
Our railway network design problem in the presence of a competing transportation
mode consists of choosing a set of stations and links so that the number
of passengers that find the railway network more attractive than an already
operating transportation mode is maximized. Due to the NP-hardness of this
problem, heuristics are needed. In this presentation a path-relinking algorithm
is proposed.
3 - A Review of Railway Rapid Transit Planning
Juan A. Mesa, University of Seville, 41092, Sevilla, Spain,
jmesa@us.es, Gilbert Laporte, Francisco A. Ortega, Federico
Perea
During last 30 years there has been an important increase in the number of
metro and commuter systems all over the world. On the one hand, construction
of such systems requires large investments and on the other hand the quality of
the service is an important social issue thus motivating the application of scientific
tools. Planning such systems gives rise to several mathematical problems
such as network and line planning, timetable, scheduling, crew rostering and
disruption management, among others. In this talk, the literature on analytical
methods for solving these problems is reviewed.
4 - A Frequency Setting Model for Auxiliary Bus Lines on
Disrupted Rapid Transit Networks
Esteve Codina, Statistics and Operational Research, UPC, Edifici
C5, Desp 216 Campus Nord, 08034, Barcelona, Spain,
esteve.codina@upc.edu, Ángel Marín, Francisco Lopez
A model is presented for dimensioning the number of services in bus lines
intended for alleviating disruption situations of regular services in metro and
Rapid Transit networks. The coordination between disrupted services and convoys
of the auxiliary bus system is taken into account and the effects of congestion
due to high levels of demand are also modeled. The model is formulated as
an nonlinear mixed integer programming problem and results of ad hoc heuristics
as well as classical methods are shown for medium size networks.