Search results for "Information systems"

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 …

Branch-and-price-and-cut for a service network design and hub location problem

2015

In the context of combined road-rail freight transport, we study the integrated tactical planning of hub locations and the design of a frequency service network. We consider a number of real-world constraints such as multiple transshipments of requests at hubs, transport time limits for requests, request splitting, and outsourcing possibilities. To our knowledge, the combination of problem features we deal with has not been described before. We present a path-based model and solve it with a branch-and-price-and-cut algorithm. Computational experiments show that large realistic instances from a major German rail freight company can be solved close to optimality within one hour on a standard …

The directed profitable rural postman problem with incompatibility constraints

2017

[EN] In this paper, we study a variant of the directed rural postman problem (RPP) where profits are asso- ciated with arcs to be served, and incompatibility constraints may exist between nodes and profitable arcs leaving them. If convenient, some of the incompatibilities can be removed provided that penalties are paid. The problem looks for a tour starting and ending at the depot that maximizes the difference between collected profits and total cost as sum of traveling costs and paid penalties, while satisfying remaining incompatibilities. The problem finds application in the domain of road transportation service, and in particular in the context of horizontal collaboration among carriers …

The periodic rural postman problem with irregular services on mixed graphs

2019

Abstract In this paper, we deal with an extension of the rural postman problem in which some links of a mixed graph must be traversed a given number of times over a time horizon. These links represent entities that must be serviced a specified number of times in some subsets of days (or periods) of the time horizon. The aim is to design a set of minimum-cost tours, one for each day/period of the time horizon, that satisfy the service requirements. We refer to this problem as the periodic rural postman problem with irregular services (PRPP–IS). Some practical applications of the problem can be found in road maintenance operations and road network surveillance, for example. In order to solve …

Using UAV Based 3D Modelling to Provide Smart Monitoring of Road Pavement Conditions

2020

Road pavements need adequate maintenance to ensure that their conditions are kept in a good state throughout their lifespans. For this to be possible, authorities need efficient and effective databases in place, which have up to date and relevant road condition information. However, obtaining this information can be very difficult and costly and for smart city applications, it is vital. Currently, many authorities make maintenance decisions by assuming road conditions, which leads to poor maintenance plans and strategies. This study explores a pathway to obtain key information on a roadway utilizing drone imagery to replicate the roadway as a 3D model. The study validates this by using stru…

Critical realism and ICT4D: editorial introduction to the special issue of EJISDC

2018

Contribución de la comunicación institucional de la investigación a su impacto y visibilidad. Caso de la Universidad Carlos III de Madrid

2020

Institutional offices for the communication and dissemination of science are gaining in importance at Spanish universities, and their activities can contribute to increasing the visibility and reputation of researchers. The objective of this study is to analyze the relations between the institutional communication of research results to the public and the impact and academic visibility of scientific papers. For this purpose, science communication and dissemination undertaken through press releases on R+D+i results from the Science Culture and Innovation Unit (SCIU) at Universidad Carlos III de Madrid (UC3M) were selected as a case study. This SCIU was chosen because it has published yearly …

Perfil sociodemográfico y actitudes políticas de los grupos a favor y en contra de limitar la libre circulación de información durante la pandemia

2020

The Covid-19 pandemic has produced not only a terrible sanitary crisis but also several problems related to the circulation of disinformation in the context of hybrid and increasingly fragmented media systems. In this work, we analyze a polemical question included in the Center for Sociological Research (CIS) survey conducted in April about the appropriateness of limiting free circulation of information to avoid diffusion of fake news and disinformation. The goals are to (1) analyze the sociodemographic traits of those in favor of limiting the free circulation of information, and (2) explore their general political preferences and affiliations, and the association with attitudes regarding f…

El periodista adaptativo. Consultores y directores de innovación analizan las cualidades del profesional de la comunicación

2016

Desde 2014 los medios de comunicación ya no luchan sólo por sobrevivir. Fundan departamentos de innovación y organizan hackatones para desarrollar nuevos productos, iniciativas que demuestran que el periodismo está mudando su piel, y vive un momento de oportunidades. Atraviesan un proceso de transición, y requieren de perfiles profesionales proactivos y flexibles que conversan con la audiencia, producen informaciones multimedia con sus móviles, utilizan puntualmente drones e incluso realizan documentales informativos con realidad aumentada. En este artículo una decena de consultores y directores de innovación que ejercen su actividad en España, Estados Unidos y Latinoamérica analizan las nu…

Eye Movement Analyses for Obtaining Readability Formula for Latvian Texts for Primary School

2017

To determine the difficulty of text, readability formulas can be used. The research was made to find readability formula for Latvian. Readability formulas for English were used as guidelines. The novelty was the use of eye movement tracking during reading to obtain quantitative data that lead to readability formula. Eye fixation durations were gathered during readability measurements. Average values of fixation durations were calculated to characterize texts and readers. 15 texts with various difficulty levels were composed for exposing them to readers. More than 300 children of grades 1 - 4 were participating in measurements. Average values of eye fixation durations of readers from a certa…