Search results for "General Computer Science"
showing 10 items of 895 documents
Short notes: Some Properties of the Rotation Lattice of Binary Trees
1988
Solving a large multicontainer loading problem in the car manufacturing industry
2017
Abstract Renault, a large car manufacturer with factories all over the world, has a production system in which not every factory produces all the parts required to assemble a vehicle. Every day, large quantities of car parts are sent from one factory to another, defining very large truck/container transportation problems. The main challenge faced by the Renault logistics platforms is to load the items into trucks and containers as efficiently as possible so as to minimize the number of vehicles sent. Therefore, the problem to be solved is a multicontainer loading problem in which, besides the usual geometric constraints preventing items from overlapping and exceeding the dimensions of the c…
Bidirectional labeling for solving vehicle routing and truck driver scheduling problems
2020
Abstract This paper studies the vehicle routing and truck driver scheduling problem where routes and schedules must comply with hours of service regulations for truck drivers. It presents a backward labeling method for generating feasible schedules and shows how the labels generated with the backward method can be combined with labels generated by a forward labeling method. The bidirectional labeling is embedded into a branch-and-price-and-cut approach and evaluated for hours of service regulations in the United States and the European Union. Computational experiments show that the resulting bidirectional branch-and-price-and-cut approach is significantly faster than unidirectional counterp…
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, …
The Multi-period Multi-trip Container Drayage Problem with Release and Due Dates
2021
Abstract The Container Drayage Problem (CDP) aims at routing a fleet of trucks, based at a common terminal, to serve customers while minimizing the total travel distance. Each trip starts from and ends at the terminal, and handles a subset of customers. Each customer requires either that a container is picked up or delivered. We introduce a more realistic variant, i.e., the Multi-trip Multi-period CDP with Release and Due Dates (MM-CDP-RDD), in which the planning horizon is composed of several periods (days). On each day, each truck may perform more than one trip respecting the Release and Due Dates (RDD) associated with customer services, corresponding to the first and the last day on whic…
High-accuracy approximation of piecewise smooth functions using the Truncation and Encode approach
2017
Abstract In the present work, we analyze a technique designed by Geraci et al. in [1,11] named the Truncate and Encode (TE) strategy. It was presented as a non-intrusive method for steady and non-steady Partial Differential Equations (PDEs) in Uncertainty Quantification (UQ), and as a weakly intrusive method in the unsteady case. We analyze the TE algorithm applied to the approximation of functions, and in particular its performance for piecewise smooth functions. We carry out some numerical experiments, comparing the performance of the algorithm when using different linear and non-linear interpolation techniques and provide some recommendations that we find useful in order to achieve a hig…
Inmigración y globalización: Acerca de los presupuestos de una política de inmigración
2003
Javier.de-Lucas@uv.es En la UE la política de inmigración supone la negación misma del inmigrante, pues no se acepta que venga aquí en otra calidad que la de trabajador. Debido a esta visión instrumental del inmigrante, el modelo de gestión de la inmigración parece sólo orientado a la lucha contra la inmigración ilegal. Se trata, por tanto, de un modelo policial de gestión de la inmigración. En España se plantean especiales problemas de política migratoria debido a la rapidez del proceso de nuestra transformación de país de emigración a país de destino, junto a la ausencia de dispositivos adecuados para gestionar esta transformación. Los principales problemas son la vinculación entre delinc…
Towards an Assessment of Public Library Value
2010
PurposeThis paper aims to present a methodology, early findings, possible applications of results and lessons learned from the research study “Public libraries: value, trust and satisfaction”, which has been conducted within the public library development project ‘Father's Third Son’ in Latvia.Design/methodology/approachA combination of quantitative and qualitative methods was used (although the findings reported here are largely drawn from the quantitative study) drawing on various theories of information behaviour and use‐oriented information service evaluation.FindingsThe study gives a good picture of user information needs in Latvia, the sources they use to fulfil them and the role of p…
2021
In COVID-19 related infodemic, social media becomes a medium for wrongdoers to spread rumors, fake news, hoaxes, conspiracies, astroturf memes, clickbait, satire, smear campaigns, and other forms of deception. It puts a tremendous strain on society by damaging reputation, public trust, freedom of expression, journalism, justice, truth, and democracy. Therefore, it is of paramount importance to detect and contain unreliable information. Multiple techniques have been proposed to detect fake news propagation in tweets based on tweets content, propagation on the network of users, and the profile of the news generators. Generating human-like content allows deceiving content-based methods. Networ…
Secure, dependable and publicly verifiable distributed data storage in unattended wireless sensor networks
2010
Published version of an article from the journal : Science in China, Series F: Information Sciences. The original publication is available at Spingerlink. http://dx.doi.org/10.1007/s11432-010-0096-7 In unattended wireless sensor networks (UWSNs), sensed data are stored locally or at designated nodes and further accessed by authorized collectors on demand. This paradigm is motivated by certain scenarios where historical or digest data (e.g., average temperature in a day), instead of real-time data, are of interest. The data are not instantly forwarded to a central sink upon sensing, thereby saving communication energy for transmission. Such a paradigm can also improve data survivability by m…