Search results for " transportation"

Semantic infrastructure system with feedback: Application on traffic

2012

The Semantic Web is a powerful approach used by some intelligent applications to manage complex information in many different fields. Nevertheless, there are not standard tools to design and built the applications, therefore each problem need to be analysed separately in order to meet the requirements. In this paper is presented an overview of a system based on a semantic approach with the goal of managing real-time information. The paper studies the application of this system on ITS (Intelligent Transport Systems) as an example of a typical real-time information system. The system gathers real information from the users and the environment, making intelligent decisions and delivering real-…

Rail access charges and internal competition in high speed trains

2016

Abstract This paper develops an ex ante analysis of the introduction of on-track competition in High Speed Rail (HSR) lines. The distinctive elements of our analysis are the consideration of: (i) the vertical structure of the rail sector, (ii) operators that compete in prices and number of services, and (iii) access charges for the use of the rail infrastructure that are endogenous. We provide simulation results for three Spanish HSR routes. The socio-economic viability of entry is found to depend on whether infrastructure and rail operations are integrated or separated, and also on the policy rule to set rail access charges. Firstly, separation without entry is not an appropriate good poli…

An integrated environmental indicator for urban transportation systems: description and application

2015

A simplified version of the ecological footprint method is proposed for assessing the environmental performances of urban transportation systems. The method, starting from the knowledge of the composition of the running vehicular fleet, is here applied to a southern Italian province. It represents a synthetic indicator of the environmental pressure exerted by the system also matching the pollutant emissions with the carrying capacity of the site. Particularly, the forested area needed to absorb the CO2 emissions of the system is compared with the total forested area of the province. The results of the case-study indicates the yearly maximum distance that each vehicle of the fleet can cover …

A new procedure to determine the rheological properties of RAP binder and corresponding bituminous blends

2017

Abstract In this paper, a new and simple approach to estimate the rheological properties of Reclaimed Asphalt Pavement (RAP) binder is proposed to overcome the limitations of the conventional extraction procedure. This method is based on Dynamic Shear Rheometer tests performed on mortars composed of RAP fine fraction and virgin binder, together with a new back-calculation solution. The properties of the bituminous blends of virgin and RAP binders are obtained with a modified Nielsen model. The Voigt model is then successfully used to estimate complex modulus and phase angle of the RAP binder from the properties of the back-calculated binder blend. This procedure would prevent the need of RA…

The facility layout problem approached using a fuzzy model and a genetic search

2005

The problem of facility layout design is discussed, taking into account the uncertainty of production scenarios and the finite production capacity of the departments. The uncertain production demand is modelled by a fuzzy number, and constrained arithmetic operators are used in order to calculate the fuzzy material handling costs. By using a ranking criterion, the layout that represents the minimum fuzzy cost is selected. A flexible bay structure is adopted as a physical model of the system while an effective genetic algorithm is implemented to search for a near optimal solution in a fuzzy contest. Constraints on the aspect ratio of the departments are taken into account using a penalty fun…

The Multiple Multidimensional Knapsack with Family-Split Penalties

2021

Abstract The Multiple Multidimensional Knapsack Problem with Family-Split Penalties (MMdKFSP) is introduced as a new variant of both the more classical Multi-Knapsack and Multidimensional Knapsack Problems. It reckons with items categorized into families and where if an individual item is selected to maximize the profit, all the items of the same family must be selected as well. Items belonging to the same family can be assigned to different knapsacks; however, in this case, split penalties are incurred. This problem arises in resource management of distributed computing contexts and Service Oriented Architecture environments. An exact algorithm based on the exploitation of a specific combi…

The fuzzy p-median problem

2004

In many location models, the strong crisp assumptions, like known demands and distances, are not realistic in most cases. The fuzzy p-median problem relaxes this hypothesis giving to the decision maker a necessary degree of freedom to solve real-world problems. It allows a decision maker to improve an optimal covering of a location problem by considering partially feasible solutions in which some demand is left uncovered. Here we revise the main facts and results about this problem emphasising different specific algorithms of resolution. Finally we show that this fuzzy version can be used to analyse the global structure of a given instance of the crisp problem.

Soft-computing based heuristics for location on networks: The p-median problem

2011

We propose a genetic algorithm for the fuzzy p-median problem in which the optimal transport cost of the associated crisp problem is unknown. Our algorithm works with two populations: in one, the solutions with a better crisp transport cost are favored by the selection criterion, whereas in the second one, solutions with a better fuzzy satisfaction level are preferred. These populations are not independent. On the contrary, the first one periodically invades the second one, thus providing new starting points for finding fuzzy improvements. Our computational results also reveal the importance of choosing adequate functions for selecting the parents. Our best results are obtained with functio…

2021

One of the problems that hinder emergency in developing countries is the problem of monitoring a number of activities on inter-urban roadway networks. In the literature, the use of control points is proposed in the context of these countries in order to ensure efficient monitoring, by ensuring a good coverage while minimizing the installation costs as well as the number of accidents across these road networks. In this work, we propose an optimal deployment of these control points from several optimization methods based on some evolutionary multi-objective algorithms: the non-dominated sorting genetic algorithm-II (NSGA-II); the multi-objective particle swarm optimization (MOPSO); the streng…

An exact algorithm for the fuzzy p-median problem

1999

In this paper we propose a fuzzy version of the classical p-median problem. We consider a fuzzy set of constraints so that the decision-maker will be able to take into account solutions which provide significantly lower costs by leaving a part of the demand uncovered. We propose an algorithm for solving the problem which is based on Hakimi's works and we compare the crisp and the fuzzy approach by means of an example.