Search results for " Process"
showing 10 items of 17204 documents
System Dynamics in the Predictive Analytics of Container Freight Rates
2021
This study proposes a two-tier cross-validation and backtesting procedure, including expanding and rolling-window test metrics in predictive analytics of container freight rates by utilizing the system dynamics approach. The study utilized system dynamics to represent the nonlinear complex structure of container freight rates for predictive analytics and performed univariate and multivariate time-series analysis as benchmarks of the conventional approach. In particular, the China containerized freight index (CCFI) has been investigated through various parametric methodologies (both conventional time-series and system dynamics approaches). This study follows a strict validation process cons…
Applying particle swarm optimization to the motion-cueing-algorithm tuning problem
2017
The MCA tuning problem consists in finding the best values for the parameters/coefficients of Motion Cueing Algorithms (MCA). MCA are used to control the movements of robotic motion platforms employed to generate inertial cues in vehicle simulators. This problem is traditionally approached with a manual pilot-in-the-loop subjective tuning, based on the opinion of several pilots/drivers. Instead, this paper proposes applying Particle Swarm Optimization (PSO) to solve this problem, using simulated motion platforms and objective indicators rather than subjective opinions. Results show that PSO-based tuning can provide a suitable solution for this complex optimization problem.
Using AHP methodology for prioritizing the actions in the transport sector in the frame of SECAPs
2020
The drafting of the Sustainable Energy and Climate Action Plan, required for the local authorities joining the Covenant of Mayors initiative, is an opportunity to plan actions reducing greenhouse gas emissions in the transport sector. Choosing the measures to implement requires the application of a methodology that compares them, considering costs and impacts in terms of energy consumption, emissions reduction, and social benefits. The paper aims to develop a method based on the typical approach of the Analytical Hierarchy Process, supporting decisions in the transport sector in the frame of the drafting of SECAP. The method allows determining the priority actions and the optimal allocation…
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…
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…
Transport Logistics and Modal Split of Spanish Exports to Europe: Empirical Evidence
2006
This article attempts to find the determinants of mode choice decisions for Spanish shipments to Europe and North Africa in four productive sectors that presents differentiated transport logistics. To this end, exhaustive fieldwork was carried out and a database constructed, including 1251 observations collected from transport decision-makers. A mixed logit is used to estimate a modal choice model, consistent with economic theory of modal choice in a price-time reliability framework. The main findings are that quality attributes of service influence modal choice only for the relatively high-value sectors whereas relatively low-value sectors are mainly affected by transport costs. In terms o…
A Lexicon-based Approach for Sentiment Classification of Amazon Books Reviews in Italian Language
2016
We present a system aimed at the automatic classification of the sentiment orientation expressed into book reviews written in Italian language. The system we have developed is found on a lexicon-based approach and uses NLP techniques in order to take into account the linguistic relation between terms in the analyzed texts. The classification of a review is based on the average sentiment strenght of its sentences, while the classification of each sentence is obtained through a parsing process inspecting, for each term, a window of previous items to detect particular combinations of elements giving inversions or variations of polarity. The score of a single word depends on all the associated …
Mafia Methods, Extortion Dynamics and Social Responses
2016
This chapter is devoted to exploring both the empirical results and the policy proposals produced by the GLODERS project. Based on 631 cases of extortions, the Sicily and Calabria extortion database represents a relevant achievement in the field of the research on extortion racket and it is one of the main results of the GLODERS project. Gathering a great amount of information, our empirical analysis revealed the existence of several differences in the extortive conducts carried on within these two regions, which are presented. Moreover, the chapter introduces the legislation related to the crime of extortion. Social and legal responses to the phenomenon are then discussed.
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…
Social interaction in management group meetings: a case study of Finnish hospital.
2016
Purpose – The purpose of this paper is to understand the role of management group meetings (MGMs) in hospital organization by examining the social interaction in these meetings. Design/methodology/approach – This case study approaches social interaction from a structuration point of view. Social network analysis and qualitative content analysis are applied. Findings – The findings show that MGMs are mainly forums for information sharing. Meetings are not held for problem solving or decision making, and operational coordinating is limited. Meeting interaction is very much focused on the chair, and most of the discussion takes place between the chair and one other member, not between members…