Search results for "1103"
showing 10 items of 538 documents
A Branch-and-Cut Algorithm for the Single Truck and Trailer Routing Problem with Satellite Depots
2016
International audience; In the single truck and trailer routing problem with satellite depots (STTRPSD), a truck with a detachable trailer based at a main depot must serve the demand of a set of customers accessible only by truck. Therefore, before serving the customers, it is necessary to detach the trailer in an appropriate parking place (called either a satellite depot or a trailer point) and transfer goods between the truck and the trailer. This problem has applications in milk collection for farms that cannot be reached using large vehicles. In this work we present an integer programming formulation of the STTRPSD. This formulation is tightened with several families of valid inequaliti…
Branch-and-Price-and-Cut for the Truck-and-Trailer Routing Problem with Time Windows
2018
In this paper, we present a new branch-and-price-and-cut algorithm to solve the truck-and-trailer routing problem with time windows (TTRPTW) and two real-world extensions. In all TTRPTW variants, the fleet consists of one or more trucks that may attach a trailer. Some customers are not accessible with a truck-and-trailer combination, but can however be serviced by one if the trailer is previously detached and parked at a suitable location. In the first extension, the planning horizon comprises two days and customers may be visited either on both days or only once, in which case twice the daily supply must be collected. The second extension incorporates load transfer times depending on the …
Mathematical models for multicontainer loading problems
2017
Abstract This paper deals with the problem of a distribution company that has to serve its customers by putting first the products on pallets and then loading the pallets onto trucks. We approach the problem by developing and solving integer linear models. We start with basic models, that include the essential features of the problem, such as respecting the dimensions of the truck, and not exceeding the total weight capacity and the maximum weigh capacity on each axle. Then, we add progressively new conditions to consider the weight and volume of pallet bases and to include other desirable features for the solutions to be useful in practice, such as the position of the center of gravity and…
Branch-and-Price-and-Cut for the Active-Passive Vehicle-Routing Problem
2018
This paper presents a branch-and-price-and-cut algorithm for the exact solution of the active-passive vehicle-routing problem (APVRP). The APVRP covers a range of logistics applications where pickup-and-delivery requests necessitate a joint operation of active vehicles (e.g., trucks) and passive vehicles (e.g., loading devices such as containers or swap bodies). The objective is to minimize a weighted sum of the total distance traveled, the total completion time of the routes, and the number of unserved requests. To this end, the problem supports a flexible coupling and decoupling of active and passive vehicles at customer locations. Accordingly, the operations of the vehicles have to be s…
Mathematical models for Multi Container Loading Problems with practical constraints
2019
Abstract We address the multi container loading problem of a company that serves its customers’ orders by building pallets with the required products and loading them into trucks. The problem is solved by using integer linear models. To be useful in practice, our models consider three types of constraints: geometric constraints, so that pallets lie completely inside the trucks and do not overlap; weight constraints, defining the maximum weights supported by a truck and by each axle, as well as the position of the centre of gravity of the cargo; and dynamic stability constraints. These last constraints forbid empty spaces between pallets to avoid cargo displacement when the truck is moving, …
Singular Neumann (p, q)-equations
2019
We consider a nonlinear parametric Neumann problem driven by the sum of a p-Laplacian and of a q-Laplacian and exhibiting in the reaction the competing effects of a singular term and of a resonant term. Using variational methods together with suitable truncation and comparison techniques, we show that for small values of the parameter the problem has at least two positive smooth solutions.
A value sensitive ABM of the refugee crisis in The Netherlands
2019
We develop an agent based model to characterize the wellbeing of newcomers (i.e. asylum seeking refugees) in the context of asylum logistics using Schwartz’s theory of values. The model produces recommendations for decision-makers with respect to avoiding catastrophic outcomes and maximizing best case outcomes. We conduct analysis to show that while a relatively simple set of conditions is necessary to avoid catastrophic outcomes, these conditions are insufficient to maximize the best case outcomes. Furthermore, the conditions that maximize one best case outcome do so at the expense of another. The result is a platform for decision-makers to understand tradeoffs in policies for government a…
Dual Inequalities for Stabilized Column Generation Revisited
2014
Column generation (CG) models have several advantages over compact formulations: they provide better linear program bounds, may eliminate symmetry, and can hide nonlinearities in their subproblems. However, users also encounter drawbacks in the form of slow convergence, also known as the tailing-off effect, and the oscillation of the dual variables. Among different alternatives for stabilizing the CG process, Ben Amor et al. [Ben Amor H, Desrosiers J, Valério de Carvalho JM (2006) Dual-optimal inequalities for stabilized column generation. Oper. Res. 54(3):454–463] suggest the use of dual-optimal inequalities (DOIs) in the context of cutting stock and bin packing problems. We generalize th…
Assessment of genetically modified cotton GHB614 × T304‐40 × GHB119 for food and feed uses, import and processing under Regulation (EC) No 1829/2003 …
2018
International audience; The three-event stack cotton GHB614 x T304-40 x GHB119 was produced by conventional crossing to combine three single events, GHB614, T304-40 and GHB119. The genetically modified organisms (GMO) Panel previously assessed the three single cotton events and did not identify safety concerns. No new data on the single cotton events that could lead to modification of the original conclusions on their safety were identified. Based on the molecular, agronomic, phenotypic and compositional characteristics, the combination of the single cotton events and of the newly expressed proteins in the three-event stack cotton did not give rise to food and feed safety concern. The GMO P…
Part C notification (reference C/NL/13/01) from Suntory Holdings Limited for the import, distribution and retailing of carnation SHD-27531-4 cut flow…
2015
Requestor: European CommissionQuestion number: EFSA-Q-2015-00126; The Scientific Panel on Genetically Modified Organisms of the European Food Safety Authority (EFSA GMO Panel) has evaluated the overall safety of genetically modified (GM) carnation SHD-27531-4 cut flowers to be imported into the European Union (EU) for ornamental use. The genetic modification results in the flowers having purple petals. The stability of the new colour trait was observed over multiple vegetative generations. The purple colour of the petals comes from the altered expression levels of anthocyanins, common pigments found in edible fruits and vegetables. Considering the intended use of the GM carnation and the po…