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Detailed schedule
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Thursday 7 February:
Thursday 11:15-12:30 TA-1: COMEX Decision Making Room C.611 - Chair: B. Fortz
Thursday 11:15-12:30 TA-2: Production 1 Room C.601 - Chair: E.h. AGhezzaf
Thursday 11:15-12:30 TA-3: Global Optimization Room C.602 - Chair: D. Claeys
Thursday 11:15-12:30 TA-4: Transportation 1 Room C.603 - Chair: C. Vanovermeire
Thursday 14:00-15:40 TB-1: COMEX Health Room C.611 - Chair: G. Vanden Berghe
Thursday 14:00-15:40 TB-2: Routing Room C.601 - Chair: G.K. Janssens
Thursday 14:00-15:40 TB-3: Meta-Heuristics Room C.602 - Chair: P. Vansteenwegen
Thursday 14:00-15:40 TB-4: Transportation 2 Room C.603 - Chair: F.C.R Spieksma
- Optimisation model for empty container repositioning. (PDF)
Frederic Salmon (HEC-ULg QuantOM) Co-authors: S.Limbourg
- The Red-Blue Transportation Problem (PDF)
Wim Vancroonenburg (KU Leuven - KAHO Sint-Lieven) Co-authors: Federico Della Croce, Dries Goossens, Frits Spieksma
- The ship placement problem: Decision support through exact decomposition (PDF)
Jannes Verstichel (KU Leuven - KAHO Sint-Lieven) Co-authors: Patrick De Causmaecker, Greet Vanden Berghe
- The lockmaster's problem: a computational study (PDF)
Ward Passchyn (KU Leuven) Co-authors: S. Coene; F. C. R. Spieksma; G. Vanden Berghe; D. Briskorn; J. L. Hurink Abstract: Transportation of goods by ship is a promising alternative for transport over land. We focus on transport by ships over inland waterways and transport by sea ships entering a harbor/waterway network by passing through one or multiple locks. Locks are needed to control the water level so that large and heavy ships can continue to access the corresponding waterways. The lockmaster's problem concerns the optimal strategy for operating such a lock.
We describe a very basic situation that will act as our core problem. Consider a lock consisting of a single chamber. Ships arrive both upstream and downstream of the lock at known arrival times. The lockage duration T is the time between closing the lock for entering ships, and opening the lock so that ships can leave. We assume that all data are integral and that the lockage duration is constant. Our goal is to find a feasible lock-strategy that minimizes total waiting time of all ships. Thus, we need to determine at which moments in time the lock should move and transport ships to the other side.
The optimal solution is obtained by finding a shortest path in a graph. We first note that in an optimal schedule, all lock moves start at the arrival of a ship or at the arrival of the lock. We define a block as a sequence of consecutive up and down movements followed by a waiting period of less than 2T time units. It is shown that an optimal schedule exists that is a sequence of blocks. We build the graph by adding an edge for each of these possible blocks with a weight equal to the waiting time of the ships in this block. This gives an acyclic graph with O(n^2) edges where n is the total number of ships. The shortest s-t path then corresponds to a solution with the lowest possible waiting time. A straightforward implementation of this graph yields an algorithm with O(n^3) time complexity. A further speed-up of the algorithm can be achieved to O(n^2).
This algorithm can also be used to solve certain single machine batch scheduling problems more efficiently than the current algorithms from literature do. Relevant extensions that take into account the lock's capacity, the different priorities of ships, the water usage of a lock, and the possibility of multiple chambers, can be dealt with by slightly modifying the basic algorithm. Further, we prove that the problem with multiple non-identical chambers is strongly NP-hard when the number of chambers is part of the input.
A computational study is performed to evaluate some basic heuristics and the optimal solution algorithm developed here. The heuristics are a number of straightforward strategies to operate the lock, assuming near complete lack of information. A lock operator knows only the number of ships waiting on either side of the lock. We use a set of problem instances from literature for similar lock scheduling problems.
Thursday 16:10-17:25 TC-1: COMEX Routing Room C.611 - Chair: K. Sôrensen
Thursday 16:10-17:25 TC-2: Sets, Relations and Rankings Room C.601 - Chair: B. De Baets
Thursday 16:10-17:25 TC-3: Logistics Room C.602 - Chair: S. Demeyer
Friday 9:00-10:15 FA-1: COMEX Logistics Room C.611 - Chair: Y. Crama
- The cooperative facility location problem (PDF)
Lotte Verdonck (Hasselt University, Research Foundation Flanders (FWO)) Co-authors: Patrick Beullens, An Caris, Katrien Ramaekers, Gerrit K. Janssens
- Two- and three-dimensional strip packing: a shaking procedure (PDF)
Tony Wauters (CODeS, KAHO Sint-Lieven) Co-authors: Jannes Verstichel, Greet Vanden Berghe
- Multiperiod vehicle loading with stochastic release dates (PDF)
Thierry Pironet (University of Liège) Co-authors: Y. Arda, Y. Crama, D. Kronus, Th. Pironet, P. Van Hentenryck
Friday 9:00-10:15 FA2: Production 2 Room C.611 - Chair: D. Tuyttens
Friday 9:00-10:15 FA-3: MIP Room C.603 - Chair: T. Dokka
Friday 14:00-15:40 FB-1: COMEX automatic tuning and organization Room C.611 - Chair: T. Stützle
Friday 14:00-15:40 FB2: Disaster, Water and Biology Room C.602 - Chair: L. Porretta
Friday 14:00-15:40 FB-3: Decision Making Room C.603 - Chair: D. Goossens
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