1,720,967 research outputs found
Safety and health at work places. The possibilities of the functional spaces analysis technique for an effective approach to the problem
No full textAn improvement of a fuzzy three-level model to evaluating transport systems sustainability considering decision-maker's attitude
No full textThe concept of sustainable transport has been widely debated in recent years, given its close links with that of sustainable development, by which it can acquire significance.
This paper proposes a fuzzy theory-based methodological approach that leads to the definition of a summary indicator of sustainability, that can be used to evaluate the sustainability of a given action plan for transportation and land-use systems.
This approach, formalising the “three pillars of sustainability” concept with the theory of fuzzy systems, has the capability to deal with non-homogeneous indicators, maintaining the uncertainty associated with their evaluation and the interrelation between the overlapping dimensions of sustainability.
The paper describes the architecture of the proposed model, paying particular attention to the representation of the indicators using fuzzy sets and to the differences with the previous structure of the model
Fuzzy systems approach versus possibility theory approach for representing customers' stated preferences on freight transport services
No full textEveryday companies’ logistic managers have to make the best choice in freight transportation, evaluating alternative services according with their needs.
In the context of a wider research project1 that involved a set of companies localized in the Mechanic district of Northern Vicenza, we investigated, by a “SP” type survey, the propensity towards changing transportation service, focusing on some significant forms of transportation in terms of frequency and quantity of goods transported. The propensity for change, as a function of the choice factors, appeared to be a significant index for directing the decisions of the transport services providers towards options appreciated by users and, at the same time, compatible with future scenarios of the supply system. The objective of the research described in this paper is to find out a ranking of preference on transportation hypothetical alternatives proposed, with the necessity to maintain in the analysis phase the uncertainty associated with evaluations of the semantic type expressed by interviewees. In order to achieve this objective we used two different approaches: the first based on fuzzy sets and possibility theory (only descriptive approach) and the second based on fuzzy systems methodologies (descriptive and interpretative approach)
Fuzzy systems approach versus possibility theory approach for representing customers' stated preferences on freight transport services
No full textEveryday companies’ logistic managers are involved in choice processes addressed to the identification of the “best” solutions as regards freight transportation in supply and distribution; choices are achieved evaluating alternative services according to companies’ needs.
Otherwise transportation services providers (e.g. shipping agents), in order to better answer to the companies’ needs, offer a wide range of transportation services.
The first objective of the research described in this paper is to find out a ranking of preference on transportation hypothetical alternatives proposed, with the necessity to maintain, in the analysis phase, the uncertainty associated with evaluations of the semantic type expressed by interviewees. In order to achieve this objective two different approaches were adopted: the first based on fuzzy sets and possibility theory and the second based on fuzzy systems methodologies.
The second objective is to evaluate the capabilities of the two approaches to predict the behaviour of decision makers in the choice of freight transportation services, making a comparative analysis with the so-called ROC (Receiver Operating Characteristic) curve analysis method
Gap-acceptance behavior at a priority intersection: field observations versus experiments with driving simulator
No full textIn recent years, driving simulators have become an interesting alternative to field studies in order to analyze driving behavior.
The main goal of this work is to validate a driving simulator with reference to gap-acceptance behavior at priority intersections (specifically, the right turn maneuver at a three-leg intersection has been considered). In order to test the driving simulator ability to represent adequately a real situation, a comparison with real behavior has been carried out.
Using both field data and driving simulator data of gap-acceptance, we estimated the mean critical gap. The comparison of these mean critical gaps has been considered as a test to validate the driving simulator. In particular a descriptive analysis and a statistical analysis were performed.
The results obtained appear interesting and confirm that a driving simulator can be used for the representation of driver behavior at intersections
Comparative evaluation of Logit and Fuzzy Logic models of gap-acceptance behavior
No full textIn this study two alternative models of gap-acceptance behavior at unsignalized intersections with priority control
are compared based on their ability to predict actual diver choices. The rst is a probabilistic model of the
Logit type, while the second is a model based on Fuzzy Logic. The explanatory variables included in both models
are the size of the time interval evaluated by drivers in their acceptance/rejection process, the total (queuing
plus stop-line) delay experienced on the controlled approach, and the type of interval being evaluated (gap or
lag). Both models are estimated/identied based on eld observations of actual gap-acceptance behaviour. The
predictive power of the two models is compared using a technique known as ROC (Receiver Operating Characteristic)
curve analysis, which apparently has never been applied before in the area of transport modeling.
Our preliminary results are that the ROC curves suggest a slight superiority of the Logit model over the Fuzzy
Logic model; however, other statistics, computed in order to provide a more complete comparative analysis of
the two models, reveal no clear dominance of either model over the other
Logit model versus fuzzy logic model for representing gap-acceptance behavior
No full textGap-acceptance behavior at unsignalized intersections has been extensively studied in the field of traffic theory and engineering using various methods.
The acceptance or rejection of a certain gap is considered the result of a driver’s
decision process, affected by subjective and imprecise estimates of a set of explanatory variables considered as input. Classical probabilistic models (e.g. Logit models) and fuzzy system theory have been proposed in the past in order to describe
the gap-acceptance behavior. On the basis of experimental data collected at a priority junction, this paper presents a comparative analysis made using the so-called
ROC (Receiver Operating Characteristic) curve analysis. The statistical equivalence
of results indicates that Fuzzy models can be considered an alternative to the use of
Logit models
Using a fuzzy approach for evaluating sustainability of transportation system pollution-reducing policies: a case study
No full textIn recent years a wide debate between stakeholders and experts from different fields has developed about the concept of sustainability and sustainable development. In transportation systems analysis the idea of sustainable mobility has received increasing attention, finding a reference point in the concept of the “three pillars of sustainability”, which considers the idea of sustainability from a three-dimensional perspective (social, economic and environmental).
This paper presents an innovative Fuzzy Multi-Level (FML) model, which formalizes and implements this conceptual approach, using the theory of fuzzy systems, useful as a tool for evaluating sustainability of transportation policies.
The model works on three different levels, starting from a set of indicators used as input variables, and gives a fuzzy indicator of the sustainability offered by the alternative policies analysed; furthermore, intermediate fuzzy inference systems, based on rules formulated by experts, provide information about combined dimensions of sustainability (equity, viability and bearableness).
A comparative analysis of the FML model and the Analytic Hierarchy Process (AHP) method, applied to the evaluation of different pollution-reducing policies, has been developed. The interpretation of results yields information about the use of the FML model as an alternative to traditional methods of sustainability evaluation and suggests further developments of research to improve its effectiveness
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