DSpace collection:
http://ria.ua.pt:80/handle/10773/5870
Mon, 16 Jul 2018 06:53:53 GMT2018-07-16T06:53:53ZStatistical analysis of the occurrence and severity of crashes involving vulnerable road users
http://ria.ua.pt:80/handle/10773/22152
title: Statistical analysis of the occurrence and severity of crashes involving vulnerable road users
authors: Vilaça, Mariana; Silva, Nélia; Coelho, Margarida C.
abstract: Cities have been often organized in terms of planning with special attention to motor vehicles and not well prepared for
pedestrians and cyclists. In order to privilege active modes, there is the need to ensure the safety of these vulnerable road users.
The main objective of this paper is to implement a statistical analysis to assess the occurrence and severity of road crashes
involving vulnerable road users. This research is focused on analyzing the trends and causes of road crashes involving cyclists
and pedestrians and what are the main difficulties that people using active modes do face in their journeys. In order to reach this
objective, a database of crashes registrations involving motor vehicles and vulnerable road users from Aveiro, Portugal, between
2012 and 2015 was created. This analysis intends to evaluate the evolution of the number of crashes and to create patterns of risk
factors such as weather conditions, specific locations and singularities that might represent additional risk, profile of pedestrian or
cyclist involved. Regarding the analyzed variables that characterize crashes participations, the dependent variables considered
were: meteorological conditions, location, proximity to a pedestrians’ crosswalk and gender of the VRU.
The probability of the vulnerable road user being a pedestrian increases by 2.7 times if the crash occurs on a urban street
segment, 10.6 times if the crash occurs at a pedestrians’ crosswalk, and 3.5 times if the VRU is a female.Sun, 01 Jan 2017 00:00:00 GMThttp://ria.ua.pt:80/handle/10773/221522017-01-01T00:00:00ZColored Ray Configurations
http://ria.ua.pt:80/handle/10773/21978
title: Colored Ray Configurations
authors: Fabila, Ruy; Garcia, Alfredo; Hurtado, Ferran; Jaume, Rafel; Perez-Lantero, Pablo; Saumell, Maria; Silveira, Rodrigo; Tejel, Javier; Urrutia, Jorge
abstract: We study the cyclic sequences induced at infinity by pairwise-disjoint colored rays with apices on a given balanced
bichromatic point set, where the color of a ray is
inherited from the color of its apex. We derive a lower bound on the number of color sequences that can be realized from any fixed point set. We also examine sequences
that can be realized regardless of the point set and exhibit negative examples as well. In addition, we provide algorithms to decide whether a sequence is realizable from a given point set on a line or in convex position.Wed, 01 Jan 2014 00:00:00 GMThttp://ria.ua.pt:80/handle/10773/219782014-01-01T00:00:00ZA faster algorithm to compute the visibility map of a 1.5D terrain
http://ria.ua.pt:80/handle/10773/21971
title: A faster algorithm to compute the visibility map of a 1.5D terrain
authors: Loffler, Maarten; Saumell, M.; Silveira, Rodrigo
abstract: Given a 1.5D terrain, i.e., an x-monotone polygonal line in R 2 with n vertices, and 1 ≤ m ≤ n viewpoints
placed on some of the terrain vertices, we study the problem of computing the parts of the terrain that are
visible from at least one of the viewpoints. We present an algorithm that runs in O(n + m log m) time. This improves over a previous algorithm recently proposed.Wed, 01 Jan 2014 00:00:00 GMThttp://ria.ua.pt:80/handle/10773/219712014-01-01T00:00:00ZRegion-based approximation of probability distributions (for visibility between imprecise points among obstacles)
http://ria.ua.pt:80/handle/10773/21863
title: Region-based approximation of probability distributions (for visibility between imprecise points among obstacles)
authors: Buchin, Kevin; Kostitsyna, Irina; Loffler, Maarten; Silveira, Rodrigo
abstract: Let p and q be two imprecise points, given as probability
density functions on R 2, and let R be a set
of n line segments in R
2
. We study the problem of
approximating the probability that p and q can see
each other; that is, that the segment connecting p
and q does not cross any segment of R. To solve this
problem, we approximate each density function by a
weighted set of polygons; a novel approach to dealing
with probability density functions in computational
geometry.Wed, 01 Jan 2014 00:00:00 GMThttp://ria.ua.pt:80/handle/10773/218632014-01-01T00:00:00Z