1,721,614 research outputs found
Effects of the cross-section on the driver's behaviour approaching bicycle crossroads
No full textThis paper reports on the results of field surveys conducted at the approaching section of two bicycle crossroads in urban environment. The crossing roads are characterised by different cross-sections (one-lane and two-lane configurations) having a same marking scheme. The aim of the surveys was to evaluate the effectiveness of the specific marking scheme for the two different cross-sections and to provide relevant insight to improve the cyclist safety, based on the observed drivers’ behaviours. More specifically, the data analysis was aimed at: (i) studying the yielding behaviour of the drivers on the two bicycle configurations and evaluating the effects of the observed vehicle dynamics constraints in approaching phases; (ii) analysing drivers’ braking during the interaction with cyclist; (iii) defining a logistic regression model for predicting the drivers’ likelihood of yielding as a function of the variables describing his behaviour and the cross-section configurations. Results have stressed out a more critical driver yielding behaviour and braking performance when approaching the bicycle crossroad on the two-lane configuration. The logistic regression model have pointed out the cross-section variable to have the strongest effect on the logit of drivers yielding, determining a significant reduction of the likelihood of yielding if the interaction driver-cyclist occurs in the two-lane configuration. Overall, the obtained outcomes highlight a higher risk exposure of the cyclist crossing the two-lane configuration. The obtained outcomes imply that the same marking scheme on the two different cross-section configurations is inappropriate. It fails to induce proper driver behaviour when he/she approaches the bicycle crossing on the two-lane configuration in order to limit the cyclist's risk exposure to the values observed on the one-lane configuration. Eventually, several measures and recommendations have been defined to reduce the risk conditions identified in two-lane configuration
Radon groundwater monitoring at underground laboratories of Gran Sasso (Italy)
No full textAn automatic multiparametric equipment (groundwater temperature, electrical conductivity, pH. - Rn) has been planned and realized to study thee correlations between the variations of radon with the strain processes of the rock and transport properties related to the groundwater geochemistry. The monitoring activity at underground laboratories of Gran Sasso with a groundwater sampling period of twelve hours has been started from May 1996. From geochemical data recorded during the first year a high dynamic behaviour of shallow aquifer has been emphasized due to high permeability of the cretaceous limestones that form part of the Gran Sasso massif. Also, the residual time series analysis of the geochemical parameters has emphasised pre-co seismic in randon current in groundwater related to local seismicity
Factors affecting motorcyclists’ behavior in car-following condition
No full textCar-following (CF) maneuver plays an important role in both traffic flow analysis and road safety assessment. However, many studies on this issue have focused on the drivers’ behaviour, neglecting the different driving behaviour of the motorcycle riders and the vulnerability of this type of user. The aim of the present paper is to analyse the factors affecting the riders’ behaviour in CF condition, by using two surrogate safety indicators, Time Headway (TH) and Time To Collision (TTC). A field experiment was conducted to collect data. Twenty young motorcyclists participated in the study driving their own motorcycles, which were instrumented with a camera and a global positioning system device (GPS). A digital image processing algorithm was used to obtain CF related indicators. The results of the study showed that Time Headway (TH) and Time To Collision (TTC) are independent of each other, extending the result obtained in the literature for the four wheeled vehicles to the motorcycles. TTC and TH were therefore analyzed separately. As for TTC, it was observed that only in few cases (0.8%) the riders were found in risky condition (TTC < 5 s), confirming the role of this parameter for the detection of an impending risk. On the other hand, TH gives information about a potentially risky situation, and 99% of the riders were found in such condition (TH < 2 s). Due to the few cases in TTC risky conditions, only TH was further modelled by using the hazard-based duration analysis. Accelerated Failure Time (AFT) model specification was used, and the Weibull distribution provided the best fit of the data. The model identified four covariates affecting TH and all of them had the effect of reducing TH, increasing the collision risk. The time spent on CF condition, the speed of the motorcycle, the willingness of overtaking and the engine size of the motorcycle were the factors that reduced TH. The findings of this study could be considered in the development of microsimulation models; the factors that were found affecting the motorcyclists’ behavior in car-following condition could be considered for a more realistic simulation of the riders’ choice of Time Headway
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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