Papers by STEFANO BARBATI
Reliability and Failure Mode Analysis of a 10MW Offshore Wind Turbine
In this paper, investigations regarding the reliability on a typical 10MW offshore wind turbine h... more In this paper, investigations regarding the reliability on a typical 10MW offshore wind turbine have been carried out; in particular, different analysis methods and failure modes are considered. Moreover, the effect of propagation of each functional failure through the wind turbine is accounted. It has to be underlined that an onshore 5MW wind turbine data-base has been used; thus in order to convert the data from a 5MW onshore wind turbine into 10 MW offshore wind turbine, a proper conversion factor has been used. The reliability and availability of the whole offshore wind turbine have been calculated through the Reliability Prediction and Reliability Block Diagram (RBD). In addition, a failure mode analysis is done through FMECA, in order to pointed out the most important terms in a risk priority order. The reliability analysis has been developed using PTC Windchill Quality Solution tool
Road safety is well known to rely on a combination of the components of man, vehicle and the envi... more Road safety is well known to rely on a combination of the components of man, vehicle and the environment. The latter plays an important role through the geometric design of the infrastructure, but the road markings and signs are also highly strategic in reducing accidents, especially in the more unfavourable driving conditions, such as with low night-time visibility, or when it is raining or foggy. As part of a study on the contribution to road safety of high-visibility road markings with dropped-on materials, a new test protocol has been defined for verifying the surface friction requirements, at the same time studying which parameter might be most effective and representative of the in situ performances of the products, depending on the maintenance state of the pavement. This has led to the identification of more effective criteria of judgement than those reported in the current European standards (EN 1436:2008).
Laboratory Performance-Based Evaluation of Cold Bituminous Mixtures for Patching Applications
This paper describes how a flexible pavement under repeated loading cycles and environmental cond... more This paper describes how a flexible pavement under repeated loading cycles and environmental conditions is subjected to progressive deterioration and aging. For local roads, two of the main surface distresses on bituminous pavement are raveling and localized depression, which leads rapidly to potholes. Since these localized-hazardous failures compromise safety and pavement serviceability, they must be repaired as soon as they occur. Usually, the temporary rehabilitation of local roads subjected to potholes is managed by public administration as emergency treatment or planned maintenance, by using cold bituminous mixtures that are often not able to guarantee a long-lasting pavement repair. In this sense, innovative and high-performance cold bituminous mixtures have been recently optimized, replacing the traditionally used bituminous emulsion with special bitumen, resins, anti-stripping agents and several additional ingredients. This paper improves the knowledge of these products used...
MARE-WINT, 2016
In this chapter, the authors explain how to perform the core analysis of a Reliability Centered M... more In this chapter, the authors explain how to perform the core analysis of a Reliability Centered Maintenance (RCM) process for an offshore wind turbine. The aim is to provide an engineering guide which can improve the maintenance of the system, and consequently increases its availability and the production of energy. The initial investigations have been carried out using a database for an onshore 5 MW wind turbine; the data has then been converted using a proper conversion factor, so that it can be used for a 10 MW offshore turbine case. The reliability and availability of the entire offshore wind turbine have been calculated through Reliability Prediction and a Reliability Block Diagram (RBD). In addition, a failure mode analysis is done using FMECA, in order to identify the most important failure modes in a risk priority order, and to the note the effect of propagation of each functional failure. The maintenance part of the RCM analysis has also been studied, to facilitate the creation of an optimum packaging of preventive maintenance tasks, which can help to avoid the functional failures of items throughout the system.
Use of the Ground Penetrating Radar (GPR) for the Distress Evaluation of Flexible Pavements
Acoustic Absorption Potential of Porous Wearing Course Mixtures
In this paper the Authors present the results obtained in an experimental investigation which was... more In this paper the Authors present the results obtained in an experimental investigation which was carried out to evaluate sound absorption properties of porous bituminous mixtures. By making use of a previously developed standing wave impedance tube, tests were performed on gyratory compacted specimens of various mixtures, characterized by different aggregate structure, binder content and compaction level. Due to the non-homogeneous mass and textured surface of the specimens, acoustic tests were carried out in a number of configurations, with the subsequent calculation of minimum, average and maximum values of the frequency-dependent sound absorption coefficient α. Information extracted from such absorption spectra proved to be coherent with physical expectations and volumetric properties of the mixtures.
Sviluppo di metodologie di prova per la misura del coefficiente di assorbimento acustico dei conglomerati bituminosi
The Effect of a Temporary Work Zone on Traffic Flow and Driving Speed in a Rural Two-Lanes Road
The paper presents a study aimed at identifying atypical driver behavior along a (provincial) rur... more The paper presents a study aimed at identifying atypical driver behavior along a (provincial) rural road with road works. The work area is a temporary site, 50 metres long, located at the edge of the roadway, for the construction of a cycle track. All the work is done in daytime at the side of the carriageway, which remains entirely free of obstacles. The main objective of the study is to analyze the relationship between the position of the road works and the variation of driving speed. Speed was measured at the side of the carriageway, by means of surveillance points where a video camera was positioned out of sight of the drivers. These points were identified taking into account the previous speed analysis developed by means of a driving simulator where the same track was reconstructed. The pavement was quite new and had a good texture, free of distresses or cracks. The experimental investigation was carried out without adverse weather conditions, during the daytime. The results sh...
The Human Factor in the Evaluation of a Road Layout in a Virtual Environment: A Case Study
ICSDC 2011, 2012
The paper discusses the mechanisms based on visual stimuli that influence driver behavior and, su... more The paper discusses the mechanisms based on visual stimuli that influence driver behavior and, subsequently, vehicle speed and trajectory. Road layout (i.e. the alternation of curves and tangents) must be designed in regard to a correct perception of the perspective sight. In order to consider the road from this point of view, experimental surveys have been conducted in a virtual environment (driving simulator), where real layouts have been reproduced and submitted to changes in their geometry (radii, tangent length, etc). Driver reaction in different environments has been monitored. Attention was particularly paid to the vehicular speed (always higher than the legal speed), because this parameter modifies the sight and hides layout variations, inducing a poor understanding of the limits of the occupied lane. The driving simulator proved to be a tool that can be used for the laboratory reproduction of risk situations.
Long term performance of road markings on rural roads: guide-lines for maintenance management
A lot of data has been collected concerning road marking properties deterioration in order to dev... more A lot of data has been collected concerning road marking properties deterioration in order to develop performance prediction models for correct infrastructure management. In Italy, two types of road markings are mainly used, paint or thermoplastic, based on several components (thermoplastic binder systems, paint, epoxy, methyl-methacrylate, polyester, polyurea, waterborne paint, modified urethane). Vehicle tyres are abrasive and remove paint and thermoplastic markings, but these have different service life, due to their different surface adhesion and skid resistance properties. In the last years, the budget for transport infrastructure has been heavily cut and this has led to a decrease in monitoring and maintenance activities. Thus, road markings have been left in place longer than scheduled. Monitoring of the long-term performance of horizontal markings began in 2008, on behalf of some Italian road authorities, with the aim of focusing on wearing course surface deterioration, carr...
Experimental Investigation on Road Marking Distress Evolution: Beyond Testing, Quality Assurance and Maintenance Improvement
Advanced Materials Research, 2013
Road markings should always be visible, readable and effective. Their performance is related to t... more Road markings should always be visible, readable and effective. Their performance is related to the quality of materials, their application and textural characteristics of the road pavement. The evolution of properties (visibility, skid resistance, color and durability) also depends on the product, its resistance to traffic abrasion, the application technique and adhesion between coating and substrate. This paper analyzes the results of a wide campaign of tests (over more than 4,000 km of lines) on road marking performances, with the purpose of evaluating a model for design and maintenance management. Mainly post-sprayed coatings are investigated with regard to quality controls, their frequency and protocols, according to the standards in force.
An evaluation of use of synthetic waxes in warm mix asphalt
Advanced Testing and Characterization of Bituminous Materials, 2009
Advances in Human-Computer Interaction, 2011
Driving is the result of a psychological process that translates data, signals and direct/indirec... more Driving is the result of a psychological process that translates data, signals and direct/indirect messages into behavior, which is continuously adapted to the exchange of varying stimuli between man, environment and vehicle. These stimuli are at times not perceived and at others perceived but not understood by the driver, even if they derive from tools (vertical signs, horizontal marking) specifically conceived for his safety. The result is unsafe behavior of vehicle drivers. For this reason, the road environment needs to be radically redesigned. The paper describes a research, based on real and virtual environment surveys, aimed to better understand drivers' action-reaction mechanisms inside different scenarios, in order to gain informations useful for a correct organization (design) of the road space. The driving simulator can help in developing, from road to laboratory, the study of new road design tools (geometrical, compositional, constructive ones, street furniture, etc.)...
Procedia - Social and Behavioral Sciences, 2012
The paper presents the results of a study developed in order to highlight the effect of a visual ... more The paper presents the results of a study developed in order to highlight the effect of a visual stimulus on driving behavior. One bidirectional route and three different lighting conditions were monitored: a reference scenario with light evenly spread; a second and a third scenario, with an attenuation of light. The results highlighted the role of the environmental brightness on driving behavior, all other conditions being equal. In particular, the effect of darkness on drivers' actions displayed the difficulties that arise in the interpretation of volumes, spaces and distances when the perception of the road environment worsens.
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Papers by STEFANO BARBATI