1,995 research outputs found
Apparent horizon and gravitational thermodynamics of Universe in the Eddington-Born-Infeld theory
The thermodynamics of Universe in the Eddington-Born-Infeld (EBI) theory was
restudied by utilizing the holographic-style gravitational equations that
dominate the dynamics of the cosmical apparent horizon and the
evolution of Universe. We started in rewriting the EBI action of the Palatini
approach into the Bigravity-type action with an extra metric . With
the help of the holographic-style dynamical equations, we discussed the
property of the cosmical apparent horizon including timelike,
spacelike and null characters, which depends on the value of the parameter of
state in EBI Universe. The unified first law for the gravitational
thermodynamics and the total energy differential for the open system enveloped
by in EBI Universe were obtained. Finally, applying the
positive-heat-out sign convention, we derived the generalized second law of
gravitational thermodynamics in EBI universe.Comment: 23 pages, 0 figure
Analytical controllability of deterministic scale-free networks and Cayley trees
According to the exact controllability theory, the controllability is
investigated analytically for two typical types of self-similar bipartite
networks, i.e., the classic deterministic scale-free networks and Cayley trees.
Due to their self-similarity, the analytical results of the exact
controllability are obtained, and the minimum sets of driver nodes (drivers)
are also identified by elementary transformations on adjacency matrices. For
these two types of undirected networks, no matter their links are unweighted or
(nonzero) weighted, the controllability of networks and the configuration of
drivers remain the same, showing a robustness to the link weights. These
results have implications for the control of real networked systems with
self-similarity.Comment: 7 pages, 4 figures, 1 table; revised manuscript; added discussion
about the general case of DSFN; added 3 reference
Shortest Path and Distance Queries on Road Networks: An Experimental Evaluation
Computing the shortest path between two given locations in a road network is
an important problem that finds applications in various map services and
commercial navigation products. The state-of-the-art solutions for the problem
can be divided into two categories: spatial-coherence-based methods and
vertex-importance-based approaches. The two categories of techniques, however,
have not been compared systematically under the same experimental framework, as
they were developed from two independent lines of research that do not refer to
each other. This renders it difficult for a practitioner to decide which
technique should be adopted for a specific application. Furthermore, the
experimental evaluation of the existing techniques, as presented in previous
work, falls short in several aspects. Some methods were tested only on small
road networks with up to one hundred thousand vertices; some approaches were
evaluated using distance queries (instead of shortest path queries), namely,
queries that ask only for the length of the shortest path; a state-of-the-art
technique was examined based on a faulty implementation that led to incorrect
query results. To address the above issues, this paper presents a comprehensive
comparison of the most advanced spatial-coherence-based and
vertex-importance-based approaches. Using a variety of real road networks with
up to twenty million vertices, we evaluated each technique in terms of its
preprocessing time, space consumption, and query efficiency (for both shortest
path and distance queries). Our experimental results reveal the characteristics
of different techniques, based on which we provide guidelines on selecting
appropriate methods for various scenarios.Comment: VLDB201
Methyl 3-(4-chlorophenyl)-2-(1,3-dimethyl-2,5-dioxo-4-phenylimidazolidin-4-yl)-3-oxopropanoate
The title compound, C21H19ClN2O5, is a tetrasubstituted hydantoin derivative which contains an imidazolidine-2,4-dione core. The dihedral angle between the aromatic rings is 64.53 (14)°. In the crystal, weak intermolecular C—H⋯O hydrogen bonding is found. An intramolecular C—H⋯O interaction also occurs
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