1,720,980 research outputs found
Multiscale methods for traffic flow on networks
Full text linkIn this thesis we propose a model to describe traffic
flows on network by the theory of measure-based
equations. We first apply our approach to the initial/boundary-value problem for the measure-valued
linear transport equation on a bounded interval, which is the prototype of an arc of the network.
This simple case is the first step to build the solution of the respective linear problem on networks:
we construct the global solution by gluing all the measure-valued solutions on the arcs by means of
appropriate distribution rules at the vertices.
The linear case is adopted to show the well-posedness for the transport equation on networks in case of
nonlocal velocity fields, i.e. which depends not only on the state variable, but also on the solution itself.
It is also studied a representation formula in terms of the push-forward of the initial and boundary
data along the network along the admissible trajectories, weighted by a properly dened measure on
curves space. Moreover, we discuss an example of nonlocal velocity eld tting our framework and
show the related model features with numerical simulations.
In the last part, we focus on a class of optimal control problems for measure-valued nonlinear transport
equations describing traffic
ow problems on networks. The objective is to optimize macroscopic
quantities, such as traffic volume, average speed, pollution or average time in a fixed area, by controlling
only few agents, for example smart traffic lights or automated cars. The measure-based approach
allows to study in the same setting local and nonlocal drivers interactions and to consider the control
variables as additional measures interacting with the drivers distribution. To complete our analysis,
we propose a gradient descent adjoint-based optimization method and some numerical experiments in
the case of smart traffic lights for a 2-1 junction
Path functionals over Wasserstein spaces
No full textGiven a metric space we consider a general class of functionals which measure the cost of a path in joining two given points and , providing abstract existence results for optimal paths. The results are then applied to the case when is a Wasserstein space of probabilities on a given set and the cost of a path depends on the value of classical functionals over measures. Conditions to link arbitrary extremal measures and by means of finite cost paths are given
A model for the optimal planning of an urban area
No full textWe propose a model to describe the optimal distributions of residents and services in a prescribed urban area. The cost functional takes into account the transportation costs (according to a Monge-Kantorovich-type criterion) and two additional terms which penalize concentration of residents and dispersion of services. The tools we use are the Monge-Kantorovich mass transportation theory and the theory of nonconvex functionals defined on measures
Asymptotic optimal location of facilities in a competition between population and industries
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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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Congested traffic dynamics, weak flows and very degenerate elliptic equations
No full textAbstractStarting from a model of traffic congestion, we introduce a minimal-flow-like variational problem whose solution is characterized by a very degenerate elliptic PDE. We precisely investigate the relations between these two problems, which can be done by considering some weak notion of flow for a related ODE. We also prove regularity results for the degenerate elliptic PDE, which enables us in some cases to apply the DiPerna–Lions theory
A Benamou-Brenier approach to branched transport
Full text linkSUMMARY The problem of branched transportation aims to describe the movement of
masses when, due to concavity effects, they have the interest to travel
together as much as possible, because the cost for a path of lengt
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