12,883 research outputs found
Self-Similarity of Friction Laws
The change of the friction law from a mesoscopic level to a macroscopic level
is studied in the spring-block models introduced by Burridge-Knopoff. We find
that the Coulomb law is always scale invariant. Other proposed scaling laws are
only invariant under certain conditions.}Comment: Plain TEX. Figures not include
Efeito do meio de cultura na germinação do pólen de espinheira santa (Maytenus ilicifolia Mart.).
Organizado por Patricia Póvoa de Mattos, Celso Garcia Auer, Rejane Stumpf Sberze, Katia Regina Pichelli e Paulo César Botosso
Pauli-Lubanski scalar in the Polygon Approach to 2+1-Dimensional Gravity
In this paper we derive an expression for the conserved Pauli-Lubanski scalar
in 't Hooft's polygon approach to 2+1-dimensional gravity coupled to point
particles. We find that it is represented by an extra spatial shift in
addition to the usual identification rule (being a rotation over the cut). For
two particles this invariant is expressed in terms of 't Hooft's phase-space
variables and we check its classical limit.Comment: Some errors are corrected and a new introduction and discussion are
added. 6 pages Latex, 4 eps-figure
The walkability of Alvalade neighbourhood for young people: An agent-based model of daily commutes to school
The Alvalade neighbourhood in Lisbon, Portugal, was built in the mid-XX century as low-cost housing for workers,
but it has become inhabited by the middle and upper classes. The neighbourhood is home to a large population of
young people, including children and teenagers who attend the schools located in the area. We present an agent-
based model which aims to investigate the walkability of the neighbourhood for these young people, focusing on
the mobility patterns of children and teenagers as they navigate their daily routines of going to school. We simulate
the pedestrian movement of these young people, considering factors such as the availability of sidewalks,
crosswalks, distance to schools, and the presence of other amenities. Our research reveals the mobility patterns
emerging in this area and compares them across the different schools in the area. These results inform both urban
policies and interventions that promote safe and accessible routes to school.info:eu-repo/semantics/publishedVersio
Random-walk mobility analysis of Lisbon’s plans for the post-1755 reconstruction
The different options for the reconstruction of the city of Lisbon in the aftermath of the 1755 earthquake are studied with an agent-based model based on randomwalks. This method gives a comparative quantitative measure of mobility of the circulation spaces within the city. The plans proposed for the city of Lisbon signified a departure from the medieval mobility city model. The intricacy of the old city circulation spaces is greatly reduced in the new plans and the mobility between different areas is substantially improved. The simulation results of the random-walk model show that those plans keeping the main force lines of the old city presented less improvement in terms ofmobility. The plans that had greater design freedom were, by contrast, easier to navigate. Lisbon's reconstruction followed a plan that included a shift in the traditional notions of mobility. This affected the daily lives of its citizens by potentiating an easy access to the waterfront, simplifying orientation and navigability. Using the random-walk model it is shown how to quantitatively measure the potential that synthetic plans have in terms of the permeability and navigability of different city public spaces.info:eu-repo/semantics/publishedVersio
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