Search results for "mathematics"
showing 10 items of 22031 documents
Asymmetry matters: Dynamic half-way points in bidirectional labeling for solving shortest path problems with resource constraints faster
2017
Abstract With their paper “Symmetry helps: Bounded bi-directional dynamic programming for the elementary shortest path problem with resource constraints” [Discrete Optimization 3, 2006, pp. 255–273] Righini and Salani introduced bounded bidirectional dynamic programming (DP) as an acceleration technique for solving variants of the shortest path problem with resource constraints (SPPRC). SPPRCs must be solved iteratively when vehicle routing and scheduling problems are tackled via Lagrangian relaxation or column-generation techniques. Righini and Salani and several subsequent works have shown that bounded bidirectional DP algorithms are often superior to their monodirectional counterparts, s…
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…
Using Genetic Algorithms for Optimizing the PPC in the Highway Horizontal Alignment Design.
2016
Various studies have emphasized the interesting advantages related to the use of new transition curves for improving the geometric design of highway horizontal alignments. In a previous paper, one of the writers proposed a polynomial curve, called a polynomial parametric curve (PPC), proving its efficiency in solving several design problems characterized by a very complex geometry (egg-shaped transition, transition between reversing circular curves, semidirect and inner-loop connections, and so on). The PPC also showed considerable advantages from a dynamic perspective, as evidenced by the analysis of the main dynamic variables related to motion (as well as rate of change of radial accelera…
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…
The impact of an urban toll ring on housing prices
2020
Abstract Building on standard urban economics theory we set up a stylized model within which we demonstrate that the imposition of a toll ring leads to higher housing prices within the ring, and lower outside the ring. We examine this prediction empirically by using transaction data for 15,306 dwellings in the Norwegian town of Kristiansand, where since 1992 there has been a toll ring. We find that the toll ring implies 6.9 per cent higher housing prices within the toll ring than outside it. The relationship between toll fees and housing prices seems to be stable over time. The impact of the toll ring on the prices of detached houses, apartments, row houses and twin houses is strikingly dif…
Analysis of Kinematic Parameters and Driver Behavior at Turbo Roundabouts
2018
This study focuses on both vehicle kinematic parameters (speed and acceleration) and behavior parameters (critical interval and follow-up time) of drivers at turbo-roundabouts. Empirical evaluations of such parameters can be helpful in calibrating traffic microsimulation models or assigning behavior parameters to closed-form capacity models in turbo-roundabouts (gap-acceptance capacity models) and are also related to evaluation of vehicles pollutant emissions. The research was based on traffic process observed in the first turbo-roundabout implemented in the city of Maribor in Slovenia. In 2016 a great number of traffic samples were taken with high-frame-rate video recordings [>50 frames pe…
A stochastic dynamical social model involving a human happiness index
2018
[EN] This paper presents a new human happiness index built through five dimensions: development, freedom, solidarity, justice and peace. These five dimensions are evaluated through quantitative variables obtained from the Human Development Reports, World Data Bank and Eurostat. The new happiness index has been built following the guidelines set by the Human Development Reports of the UN for the construction of quality indices, and it has been compared on a set of 13 EU countries with the Overall Life Satisfaction Index, which is used by the UN. Moreover, the new index has been included in a dynamic mathematical model through the demographic rates to study the evolution of the population. Th…
Probabilistic cross-validation estimators for Gaussian process regression
2018
Gaussian Processes (GPs) are state-of-the-art tools for regression. Inference of GP hyperparameters is typically done by maximizing the marginal log-likelihood (ML). If the data truly follows the GP model, using the ML approach is optimal and computationally efficient. Unfortunately very often this is not case and suboptimal results are obtained in terms of prediction error. Alternative procedures such as cross-validation (CV) schemes are often employed instead, but they usually incur in high computational costs. We propose a probabilistic version of CV (PCV) based on two different model pieces in order to reduce the dependence on a specific model choice. PCV presents the benefits from both…
Digital Literacy
2020
Digital literacy is a widely used concept that has become pluralistic, often avoiding a clear definition of what digital literacy actually means. However, acquiring digital literacy is still a global issue. Given the vast potential of digital technology as it grows and evolves, it is essential to understand what the concept of digital literacy is and how it is applied in today's context. The aim of the study was twofold: (a) to analyse the recent literature available in the EBSCO database regarding definitions of digital literacy; and (b) to provide an overview of the concept of digital literacy and related skills. Using a systematic literature review, 45 academic papers were selected, of w…
Videogames and Inclusive Education project in Palermo Secondary School
2017
Attempting to support videogames for education and learning purposes has prompted considerable attention over the last years. The great variety of digital games available has provided much for educators and researchers to explore, resulting in intense disputes that many games have benefits both in and out of the classroom for learners of secondary school. Many games have been revealed as strong educational tools for their design as well as their effective implementation in the classroom. Thus far, research on the impact and outcomes of this pedagogy is somewhat limited, but promising. Further projects and evaluations are required to provide the support needed in order to encourage more teac…