ORBEL 24

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Detailed schedule

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Thursday 28, 2010
8:30-9:00Registration - Welcome coffee
9:00-9:30Welcoming session - Room 030
9:30-10:30Plenary session: P. Baptiste
Sustainable Development: How can we help

Room 030
10:30-11:00Coffee break
11:00-12:40Parallel sessions
  Timetabling in education and sport
Chair: G. Vanden Berghe
Room: 126
Transportation management
Chair: F. Semet
Room: 130
Networks
Chair: B. Fortz
Room: 138
Nonconvex optimization 1
Chair: F. Bach
Room: 035
12:40-14:00Lunch (and board meeting)
14:00-15:40Parallel sessions
  Constraint programming models 1
Chair: Y. Deville
Room: 126
Vehicle routing
Chair: S. Limbourg
Room: 130
Combinatorial optimization and IP applications
Chair: Q. Louveaux
Room: 138
Nonconvex Optimization 2
Chair: R. Sepulchre
Room: 035
15:40-16:10Coffee break
16:10-17:50Parallel sessions
  Constraint programming models 2
Chair: P. Schaus
Room: 126
Performance modeling
Chair: G. Janssens
Room: 130
Scheduling
Chair: K. Sorensen
Room: 138
Planning under uncertainty
Chair: R. Leus
Room: 035
17:50-General Assembly (Room 138)
18:45-Conference dinner

Friday 29, 2010
9:00-10:40Parallel sessions
  Metaheuristics
Chair: J. Teghem
Room: 126
Production and distribution (9:25)
Chair: Y. Arda
Room: 130
Multiple criteria
Chair: R. Bisdorff
Room: 138
Stochastic models (9:25)
Chair: L. Esch
Room: 035
10:40-11:00Coffee break
11:00-12:40Parallel sessions
  Constraint programming and Supply Chain Management
Chair: Y. Deville
Room: 126
OR in health management
Chair: P. De Causmaecker
Room: 130
Rankings and importance indices
Chair: JL. Marichal
Room: 138
Queueing
Chair: S. Wittevrongel
Room: 035
12:40-14:00Lunch
14:00-15:00Plenary session: M. Goemans
The Power of Matroids

Room 030
15:10-16:00Parallel sessions
  Optimization software
Chair: E. Loute
Room: 126
Integrated operations planning
Chair: B. Raa
Room: 130
Cycles in graphs
Chair: F. Spieksma
Room: 138
 
16:00-16:35Plenary session: ORBEL award and closing session
Room 030
16:35-...Coffee break
Show all the abstracts
Thursday 11:00:00 Timetabling in education and sport
Room 126 - Chair: G. Vanden Berghe

Thursday 11:00:00 Transportation management
Room 130 - Chair: F. Semet

Thursday 11:00:00 Networks
Room 138 - Chair: B. Fortz

Thursday 11:00:00 Nonconvex optimization 1
Room 035 - Chair: F. Bach

Thursday 14:00:00 Constraint programming models 1
Room 126 - Chair: Y. Deville

Thursday 14:00:00 Vehicle routing
Room 130 - Chair: S. Limbourg

Thursday 14:00:00 Combinatorial optimization and IP applications
Room 138 - Chair: Q. Louveaux

Thursday 14:00:00 Nonconvex Optimization 2
Room 035 - Chair: R. Sepulchre

Thursday 16:10:00 Constraint programming models 2
Room 126 - Chair: P. Schaus

Thursday 16:10:00 Performance modeling
Room 130 - Chair: G. Janssens

Thursday 16:10:00 Scheduling
Room 138 - Chair: K. Sorensen

Thursday 16:10:00 Planning under uncertainty
Room 035 - Chair: R. Leus

Friday 09:00:00 Metaheuristics
Room 126 - Chair: J. Teghem

Friday 09:25:00 Production and distribution (9:25)
Room 130 - Chair: Y. Arda

Friday 09:00:00 Multiple criteria
Room 138 - Chair: R. Bisdorff

Friday 09:25:00 Stochastic models (9:25)
Room 035 - Chair: L. Esch

Friday 11:00:00 Constraint programming and Supply Chain Management
Room 126 - Chair: Y. Deville
  • A CLP engine for product configuration
    Dario Campagna (University of Perugia)
  • Just-In-Time Scheduling with Constraint Programming
    Jean-noël Monette (Université catholique de Louvain)
    Co-authors: Yves Deville, Pascal Van Hentenryck
  • Tank allocation for liquid bulk vessels using a hybrid constraint programming approach
    Rowan Van Schaeren (Antwerp Maritime Academy)
    Abstract:
    The chemical industry is characterized by a very strong competitive environment. This leads to an increased pressure on providing consistent quality, fast delivery and cost-cuttings. Chemicals are transported all over the world in special, dedicated vessels. These chemical tankers form an important aspect of this liquid bulk chemicals trade and the number of chemical tankers available on the market increases steadily. Chemical tankers distinguish themselves from other tankers in the large number of separate cargo tanks available to load cargo. Some chemical tankers have over 30 individual tanks. This allows for many different cargoes to be transported simultaneously, but requires that each cargo tank has its own pump and piping system to connect with the shore in order to prevent mixing or contaminating individual cargoes. This also has an important impact on the planning of cargoes on board of these chemical tankers as cargo interactions can result in dangerous situations. Almost all chemical products can be considered dangerous one way or the other (being labeled as e.g. corrosive, marine pollutant, toxic ...). These products must therefore be stored in accordance with stringent regulations. Concerning stowage the most important criterion is segregation. Segregation is not only important between the different products themselves (certain products like e.g. caustic soda and sulfuric acid cannot be stowed in adjacent tanks) but also with respect to the tank coatings that protect the tanks from products stored in them. In addition to this, the vessel's stability constraints complicate the capacity planning even further. Because of the computational complexity of mathematically optimizing the problem, loading plans are generally generated manually by the vessel planners and checked by a stability program afterward. Because of the multitude of constraints, regulations and ``good practices'', it is very difficult to generate high quality loading plans manually. Optimization methods capable of handling these side constraints and generating high quality solutions can therefore greatly support vessel planners and free up time for handling non-standard scheduling issues. Academic literature on the tank allocation problem (TAP) or operational planning is limited. Most of the conducted research considers both the load planning and vessel routing of chemical tankers. However, only a few deal with segregation and stability constraints simultaneously in their load planning, which are essential in real-life applications. The literature review illustrates the difficulties of simultaneously addressing both planning and routing aspects for loading chemical vessels even if no or only simplified ship stability constraints are taken into account. As this research aims at modeling the stability of chemical tankers in full detail, we start by focusing on the load planning part of the problem. Although the loading aspect of chemical vessels can be addressed successfully by mixed integer programming, constraint programming (CP) looks more promising for developing an integrated model in the future, in which both the scheduling of several ports aspect and the load planning of cargo aspect are combined. In the proposed model, CP is used for making the allocations of cargo to the tanks and LP is dynamically used as a final constraint checker for the ship stability at the potential solution nodes of the search tree. More precisely, at a potential solution node of the CP search tree, every tank is empty or is allocated to a cargo ensuring that there is enough volume for each cargo while satisfying segregation constraints. The LP is then called as a subroutine to check and optimize the stability constraints deciding how many tons of the cargo will be allocated to each tank by considering the cargo allocation as given. If the stability requirements cannot be satisfied by the LP the node is simply discarded. This simple hybridization between CP (Master) and LP (slave) is used in a Branch and Bound scheme to maximize the unused free space of the tanks. Computational results with Comet show that this hybrid CP-LP approach is an interesting path for solving the operational planning problem of chemical tankers (load planning and scheduling). Computational times prove to be operationally acceptable with the proposed model. Our current research focuses on finding a good CP search algorithm, as this is critical concerning computation times. Integrating the ship routing and scheduling into the operational planning will be the topic of future research.
  • Effective Estimation-based Stochastic Local Search Algorithms for Stochastic Routing Problems
    Thomas Stützle (Université Libre de Bruxelles (ULB) )
    Co-authors: Prasanna Balaprakash, Mauro Birattari, Marco Dorigo

Friday 11:00:00 OR in health management
Room 130 - Chair: P. De Causmaecker

Friday 11:00:00 Rankings and importance indices
Room 138 - Chair: JL. Marichal

Friday 11:00:00 Queueing
Room 035 - Chair: S. Wittevrongel

Friday 15:10:00 Optimization software
Room 126 - Chair: E. Loute

Friday 15:10:00 Integrated operations planning
Room 130 - Chair: B. Raa

Friday 15:10:00 Cycles in graphs
Room 138 - Chair: F. Spieksma

 
 
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