61 research outputs found
Large scale stochastic inventory routing problems with split delivery and service level constraints
A stochastic inventory routing problem (SIRP) is typically the combination of stochastic inventory control problems and NP-hard vehicle routing problems, which determines delivery volumes to the customers that the depot serves in each period, and vehicle routes to deliver the volumes. This paper aims to solve a large scale multi-period SIRP with split delivery (SIRPSD) where a customer’s delivery in each period can be split and satisfied by multiple vehicle routes if necessary. This paper considers SIRPSD under the multi-criteria of the total inventory and transportation costs, and the service levels of customers. The total inventory and transportation cost is considered as the objective of the problem to minimize, while the service levels of the warehouses and the customers are satisfied by some imposed constraints and can be adjusted according to practical requests. In order to tackle the SIRPSD with notorious computational complexity, we first propose an approximate model, which significantly reduces the number of decision variables compared to its corresponding exact model. We then develop a hybrid approach that combines the linearization of nonlinear constraints, the decomposition of the model into sub-models with Lagrangian relaxation, and a partial linearization approach for a sub model. A near optimal solution of the model found by the approach is used to construct a near optimal solution of the SIRPSD. Randomly generated instances of the problem with up to 200 customers and 5 periods and about 400 thousands decision variables where half of them are integer are examined by numerical experiments. Our approach can obtain high quality near optimal solutions within a reasonable amount of computation time on an ordinary PC
Desorption electrospray ionization (DESI) mass spectrometry and tandem mass spectrometry (MS/MS) of phospholipids and sphingolipids: Ionization, adduct formation, and fragmentation
The UEFA Champions League seeding is not strategy-proof since the 2015/16 season
Fairness has several interpretations in sports, one of them being that the
rules should guarantee incentive compatibility, namely, a team cannot be worse
off due to better results in any feasible scenario. The current seeding regime
of the most prestigious annual European club football tournament, the UEFA
(Union of European Football Associations) Champions League, is shown to violate
this requirement since the 2015/16 season. In particular, if the titleholder
qualifies for the first pot by being a champion in a high-ranked league, its
slot is given to a team from a lower-ranked association, which can harm a top
club from the domestic championship of the titleholder. However, filling all
vacancies through the national leagues excludes the presence of perverse
incentives. UEFA is encouraged to introduce this policy from the 2021-24 cycle
onwards.Comment: 11 pages, 1 figure, 1 tabl
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Stability Characterization of a Polysorbate 80-Dimethyl Trisulfide Formulation, a Cyanide Antidote Candidate
Solving multi-product inventory ship routing with a heterogeneous fleet model using a hybrid cross entropy-genetic algorithm: a case study in Indonesia
The effect on home advantage when a team changes from grass to artificial turf – a worldwide study in professional football
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