977 research outputs found
Charged Cylindrical Collapse of Anisotropic Fluid
Following the scheme developed by Misner and Sharp, we discuss the dynamics
of gravitational collapse. For this purpose, an interior cylindrically
symmetric spacetime is matched to an exterior charged static cylindrically
symmetric spacetime using the Darmois matching conditions. Dynamical equations
are obtained with matter dissipating in the form of shear viscosity. The effect
of charge and dissipative quantities over the cylindrical collapse are studied.
Finally, we show that homogeneity in energy density and conformal flatness of
spacetime are necessary and sufficient for each other.Comment: 19 pages, accepted for publication in Gen. Relativ. Gra
Dynamics of Viscous Dissipative Plane Symmetric Gravitational Collapse
We present dynamical description of gravitational collapse in view of Misner
and Sharp's formalism. Matter under consideration is a complicated fluid
consistent with plane symmetry which we assume to undergo dissipation in the
form of heat flow, radiation, shear and bulk viscosity. Junction conditions are
studied for a general spacetime in the interior and Vaidya spacetime in the
exterior regions. Dynamical equations are obtained and coupled with causal
transport equations derived in context of Mller Israel Stewart
theory. The role of dissipative quantities over collapse is investigated.Comment: 17 pages, accepted for publication in Gen. Relativ. Gra
Dynamics of Non-adiabatic Charged Cylindrical Gravitational Collapse
This paper is devoted to study the dynamics of gravitational collapse in the
Misner and Sharp formalism. We take non-viscous heat conducting charged
anisotropic fluid as a collapsing matter with cylindrical symmetry. The
dynamical equations are derived and coupled with the transport equation for
heat flux obtained from the Mller-Israel-Stewart causal thermodynamic
theory. We discuss the role of anisotropy, electric charge and radial heat flux
over the dynamics of the collapse with the help of coupled equation.Comment: 15 pages, accepted for publication in Astrophys. Space Sc
Emergence of communities on a coevolutive model of wealth interchange
We present a model in which we investigate the structure and evolution of a
random network that connects agents capable of exchanging wealth. Economic
interactions between neighbors can occur only if the difference between their
wealth is less than a threshold value that defines the width of the economic
classes. If the interchange of wealth cannot be done, agents are reconnected
with another randomly selected agent, allowing the network to evolve in time.
On each interaction there is a probability of favoring the poorer agent,
simulating the action of the government. We measure the Gini index, having real
world values attached to reality. Besides the network structure showed a very
close connection with the economic dynamic of the system.Comment: 5 pages, 7 figure
Diseño de un modelo de datos de redes para el transporte multimodal
Esta comunicación tiene por objeto el análisis de las relaciones entre redes de transporte y paisaje. Se aborda el
análisis de la estructura de la red y su caracterización, para dar soporte a la modelización de distintos escenarios, lo
que implica un complejo modelo de datos en el que se trabaja con una red multimodal conformada por los siguientes
modos: transporte por carretera, ferroviario, peatonal y náutico. Se hace hincapié en el transporte combinado que
emplea los diferentes modos, como ocurre frecuentemente con el viaje turÃstico. El territorio en el que se construye el
modelo, a partir de los mapas topográficos 1:5000 y 1.000, que se complementan con ortofotografÃa, es la isla de
Tenerife.This paper explores the relationship between transport networks and landscape. The network structure and its
characteristics are studied in order to support the modeling of different scenarios. This implies a complex data model
which works with a multimodal network. It is composed by different features: roads, railroads, pedestrian paths and
nautical tracks. A combined transport system (the touristic travel) employing different modalities is the focus of
interest. Tenerife Island acts as a reference of this transport system. Base maps in 1:5000 and 1:1000 scales and a
rectified photo are used
Data on the working population in Spain related to training, workplace conditions and accident rates
Obtaining data on worker accident rates is necessary in order to analyze the causes and variables involved in the occurrence of said accidents. The majority of these data, collected after the accident occurs, do not consider the employee's working conditions. Here are presented the data on workplace accidents and the conditions of the workers by analyzing the generic data supplied as part of the 7th National Survey of Workplace Conditions (EWCS) in Spain, conducted in 2011. These data will yield the variables needed to determine if the information on workplace risks provided by the survey respondents has an appreciable effect on the occurrence of occupational accidents in the working population, and will also be used to explore other variables
Voltage compensation and power factor correction in distribution networks with DVR
The stability analysis and voltage regulation in distribution systems, as well as power quality problems such as voltage sags, swells, due to connection and disconnection of large loads, short circuits and the presence of non-linear loads, require of the consideration of adequate technical solutions. In this paper, a Dynamic Voltage Restorer ( DVR ) model based on a power converter scheme for voltage compensation due to the presence of sags of amplitude since 0.1pu to 0.9pu and swells with amplitude from 1.1pu to 1.9pu, and power factor correction in distribution networks is proposed. The results are verified through MATLAB & Simulink
Space-time inhomogeneity, anisotropy and gravitational collapse
We investigate the evolution of non-adiabatic collapse of a shear-free
spherically symmetric stellar configuration with anisotropic stresses
accompanied with radial heat flux. The collapse begins from a curvature
singularity with infinite mass and size on an inhomogeneous space-time
background. The collapse is found to proceed without formation of an even
horizon to singularity when the collapsing configuration radiates all its mass
energy. The impact of inhomogeneity on various parameters of the collapsing
stellar configuration is examined in some specific space-time backgrounds.Comment: To appear in Gen. Relativ. Gra
Dynamics of Charged Plane Symmetric Gravitational Collapse
In this paper, we study dynamics of the charged plane symmetric gravitational
collapse. For this purpose, we discuss non-adiabatic flow of a viscous fluid
and deduce the results for adiabatic case. The Einstein and Maxwell field
equations are formulated for general plane symmetric spacetime in the interior.
Junction conditions between the interior and exterior regions are derived. For
the non-adiabatic case, the exterior is taken as plane symmetric charged Vaidya
spacetime while for the adiabatic case, it is described by plane
Reissner-Nordstrm spacetime. Using Misner and Sharp formalism, we
obtain dynamical equations to investigate the effects of different forces over
the rate of collapse. In non-adiabatic case, a dynamical equation is joined
with transport equation of heat flux. Finally, a relation between the Weyl
tensor and energy density is found.Comment: 21 pages, accepted for publication Gen. Relativ. Gra
Geochemical and geochronological constraints on the geologic evolution of the western Sonobari Complex, northwestern Mexico
In the southern Sierra Sonobari, NW Mexico, U-Pb and 40Ar/39Ar geochronology studies allowed to define the provenance and maximum depositional age of the Francisco Gneiss basement of the Sonobari terrane, and to establish the age of some magmatic events in that area. The youngest zircon cluster in paragneisses of the Francisco Gneiss indicates a maximum depositional age of 509 ± 29Ma. The main peaks of the relative probability plot yield ages of 1690 and 1404Ma with minor peaks at 1156, 921, and 517Ma. Major peaks suggest that the main source of sediments was the Paleo- and Mesoproterozoic crust of Laurentia. Orthogneiss from the Francisco Gneiss yields a U-Pb zircon upper intercept age of 248 ± 28Ma, which is interpreted as the crystallization age. Crosscutting dykes of metabasite yield an 40Ar/39Ar age of 67 ± 5Ma, which is interpreted as indicating cooling after either a latest Early Cretaceous orogenic event or Late Cretaceous contact metamorphism. Granodiorite intruding the Francisco Gneiss yields a U-Pb age of 64 ± 1Ma, which is interpreted as a magmatic age. The hornblende-plagioclase Macochin Gabbro yields 40Ar/39Ar isochron ages of 54 ± 10Ma and 47 ± 5Ma, which are interpreted as cooling ages after the gabbro intrusion. Geochemical data indicate that the mafic rocks of the Francisco Gneiss correspond to subalkaline basalts of tholeiitic affinity with concentrations of high field strength elements similar to oceanic basalts, suggesting an asthenospheric upper mantle source. However, according to the variation in Th/Yb and U/Yb, the amphibolites display a significant influence of the upper continental crust. The Macochin Gabbro also has a geochemical signature characteristic of subalkaline basalt with tholeiitic affinity, and high field strength elements similar to oceanic basalts. Tectonic discrimination diagrams and elemental distribution suggest that the mafic rocks of both the Francisco Gneiss and Macochin Gabbro were emplaced during rifting in a back-arc setting
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