Search results for " technologies."
showing 10 items of 2689 documents
Irregular packing problems: a review of mathematical models
2020
Abstract Irregular packing problems (also known as nesting problems) belong to the more general class of cutting and packing problems and consist of allocating a set of irregular and regular pieces to larger rectangular or irregular containers, while minimizing the waste of material or space. These problems combine the combinatorial hardness of cutting and packing problems with the computational difficulty of enforcing the geometric non-overlap and containment constraints. Unsurprisingly, nesting problems have been addressed, both in the scientific literature and in real-world applications, by means of heuristic and metaheuristic techniques. However, more recently a variety of mathematical …
Determining the best shipper sizes for sending products to customers
2014
A distribution company has to send products, packed into shippers, from the warehouse to retail shops. The number of different shipper types is regarded as a parameter given by the user, who is looking for a balance between transportation costs and stock and procurement costs. The problem is to decide the sizes of the shipper types to keep at the warehouse so as to minimize the cost of meeting the forecasted demand over the planning horizon. In this paper, we describe an integer linear programming formulation for the problem and obtaining feasible solutions. Other models, based on multiknapsack and p-median and facility location models, are for obtaining lower bounds. We study several ways …
The Chinese Postman Problem with Load-Dependent Costs
2018
[EN] We introduce an interesting variant of the well-known Chinese postman problem (CPP). While in the CPP the cost of traversing an edge is a constant (equal to its length), in the variant we present here the cost of traversing an edge depends on its length and on the weight of the vehicle at the moment it is traversed. This problem is inspired by the perspective of minimizing pollution in transportation, since the amount of pollution emitted by a vehicle not only depends on the travel distance but also on its load, among other factors. We define the problem, study its computational complexity, provide two mathematical programming formulations, and propose two metaheuristics for its soluti…
The Split Delivery Vehicle Routing Problem with Time Windows and Customer Inconvenience Constraints
2019
In classical routing problems, each customer is visited exactly once. By contrast, when allowing split deliveries, customers may be served through multiple visits. This potentially results in substantial savings in travel costs. Even if split deliveries are beneficial to the transport company, several visits may be undesirable on the customer side: At each visit the customer has to interrupt his primary activities and handle the goods receipt. The contribution of the present paper consists in a thorough analysis of the possibilities and limitations of split delivery distribution strategies. To this end, we investigate two different types of measures for limiting customer inconvenience (a m…
Activity Report of the French Transport Geographers
2007
International audience; The 2007 Répertoire des Géographes Français shows 97 geographers (on a total of 2084 listed people) working in the transportation field. The Commission de Géographie des Transports meets every year in mid-September for a thematic conference: Cergy-Pontoise in 2004 (transportation nodes), Besançon in 2005 (inter-regional transportation networks), Chambéry in 2006 (tourism and transportation, co- organized with the Commission de Géographie du Tourisme). In addition, the main theme of the 2005 Festival de Géographie in Saint Dié-des-Vosges, "World in networks", allowed many transportation geographers to present their research to a wide audience reaching outside of acade…
Donald Friedman's Interviews : Writers as Visual Artists
2018
With Volume 39, “Gestures and their Traces” INTERFACES, now an on-line journal, began its third iteration. In volume 40, we welcome Donald Friedman, novelist, essayist, and preeminently the author of The Writer’s Brush, Paintings, Drawings, and Sculpture by Writers, as a regular contributor to the journal. In the process of researching The Writer’s Brush, he video interviewed a number of contemporary writers; he is editing these tapes and these will begin a new feature of the journal. The fir...
A practical approach to estimate the degree of binder activity of reclaimed asphalt materials
2019
Using Reclaimed Asphalt (RA) in new asphalt mixtures can reduce the amount of new material required thereby saving money and natural resources. In addition, asphalt mixtures with RA have shown comparable properties and performance to that generally associated with asphalt mixtures made with 100% virgin material. However, RA content in pavement surface layers is still limited due to specification and technical limitations. For higher contents, the aged RA binder must be analysed to accurately determine the requirements for virgin binders and additives while the degree of blending (DOB) between the RA binder and the virgin binder also needs to be quantified. This is not a simple process and g…
Schedule-Based Integrated Intercity Bus Line Planning via Branch-and-Cut
2018
This work addresses integrated line planning for intercity bus lines, which differs in several respects from line planning in public transit. Passengers in intercity transportation decide on specific timetabled services to get to their destination. This is a contrast to an urban setting with higher frequencies, where it is generally sufficient to choose a line. Furthermore, intercity bus transportation in deregulated markets is usually characterized by fierce competition within and across modes. Customers are highly sensitive to price, time of day, duration, convenient access to stations, and service quality. Hence, bus line operators need to decide thoroughly on every single timetabled se…
Branch-and-Price-and-Cut for the Periodic Vehicle Routing Problem with Flexible Schedule Structures
2019
This paper addresses the periodic vehicle routing problem with time windows (PVRPTW). Therein, customers require one or several visits during a planning horizon of several periods. The possible visiting patterns (schedules) per customer are limited. In the classical PVRPTW, it is common to assume that each customer requires a specific visit frequency and offers all corresponding schedules with regular intervals between the visits. In this paper, we permit all kinds of schedule structures and the choice of the service frequency. We present an exact branch-and-price-and-cut algorithm for the classical PVRPTW and its variant with flexible schedules. The pricing problems are elementary shortes…
Cimo: An efficient 2-phases calculator of multimodal itineraries for real trans-territories based on a dynamic programming
2015
In this work we propose an exact solution for calculating multimodal itinerary. This solution is named Cimo (Calculateur d'Itineraires Multimodaux Ordonnes). Cimo is an exact optimal itineraries' calculator wherein itineraries are sorted, multimodal, and trans-territorial. The solution is based on a dynamic programming algorithm "cut", "price" and "share". This solution is multi-objectives and multi-constraints. Several versions of this algorithm are proposed following a methodological approach that enables evaluation of efficiency and complexity's gain : through theoretical calculus and benchmarks. In the first version of realistic problem, we propose a solution with itineraries calculated…