oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 46 )

2019 ( 319 )

2018 ( 372 )

2017 ( 378 )

Custom range...

Search Results: 1 - 10 of 269211 matches for " R; Silva "
All listed articles are free for downloading (OA Articles)
Page 1 /269211
Display every page Item
The relativistic statistical theory and Kaniadakis entropy: an approach through a molecular chaos hypothesis
R. Silva
Physics , 2006, DOI: 10.1140/epjb/e2007-00029-3
Abstract: We have investigated the proof of the $H$ theorem within a manifestly covariant approach by considering the relativistic statistical theory developed in [G. Kaniadakis, Phy. Rev. E {\bf 66}, 056125, 2002; {\it ibid.} {\bf 72}, 036108, 2005]. As it happens in the nonrelativistic limit, the molecular chaos hypothesis is slightly extended within the Kaniadakis formalism. It is shown that the collisional equilibrium states (null entropy source term) are described by a $\kappa$ power law generalization of the exponential Juttner distribution, e.g., $f(x,p)\propto (\sqrt{1+ \kappa^2\theta^2}+\kappa\theta)^{1/\kappa}\equiv\exp_\kappa\theta$, with $\theta=\alpha(x)+\beta_\mu p^\mu$, where $\alpha(x)$ is a scalar, $\beta_\mu$ is a four-vector, and $p^\mu$ is the four-momentum. As a simple example, we calculate the relativistic $\kappa$ power law for a dilute charged gas under the action of an electromagnetic field $F^{\mu\nu}$. All standard results are readly recovered in the particular limit $\kappa\to 0$.
The $H$-theorem in $κ$-statistics: influence on the molecular chaos hypothesis
R. Silva
Physics , 2005, DOI: 10.1016/j.physleta.2005.11.056
Abstract: We rediscuss recent derivations of kinetic equations based on the Kaniadakis' entropy concept. Our primary objective here is to derive a kinetical version of the second law of thermodynamycs in such a $\kappa$-framework. To this end, we assume a slight modification of the molecular chaos hypothesis. For the $H_{\kappa}$-theorem, it is shown that the collisional equilibrium states (null entropy source term) are described by a $\kappa$-power law extension of the exponential distribution and, as should be expected, all these results reduce to the standard one in the limit $\kappa\to 0$.
Relativistic statistical theory and generalized stosszahlansatz
R. Silva
Physics , 2006,
Abstract: We have investigated the proof of the $H$ theorem within a manifestly covariant approach by considering the relativistic statistical theory developed in [Phy. Rev. E {\bf 66}, 056125, 2002; {\it ibid.} {\bf 72}, 036108 2005]. In our analysis, however, we have not considered the so-called deformed mathematics as did in the above reference. As it happens in the nonrelativistic limit, the molecular chaos hypothesis is slightly extended within the $\kappa$-formalism, and the second law of thermodynamics implies that the $\kappa$ parameter lies on the interval [-1,1]. It is shown that the collisional equilibrium states (null entropy source term) are described by a $\kappa$ power law generalization of the exponential Juttner distribution, e.g., $f(x,p)\propto (\sqrt{1+ \kappa^2\theta^2}+\kappa\theta)^{1/\kappa}\equiv\exp_\kappa\theta$, with $\theta=\alpha(x)+\beta_\mu p^\mu$, where $\alpha(x)$ is a scalar, $\beta_\mu$ is a four-vector, and $p^\mu$ is the four-momentum. As a simple example, we calculate the relativistic $\kappa$ power law for a dilute charged gas under the action of an electromagnetic field $F^{\mu\nu}$. All standard results are readly recovered in the particular limit $\kappa\to 0$.
Effect of Trisodium Citrate on the Properties of Electrodeposited Cu2ZnSnS4 (CZTS) Layers on ZnS Thin Films Using a 2-Electrode Method  [PDF]
Gustavo A. Silva Hernandez, Ajith R. Weerasinghe
Advances in Materials Physics and Chemistry (AMPC) , 2018, DOI: 10.4236/ampc.2018.88021
Abstract: Electrodeposition of CZTS thin films on ZnS was carried using a 2-electrode method to fabricate superstrate structure solar cells. A comprehensive study was performed on the effects of trisodium citrate on the CZTS electrolyte bath. In the present investigation, it is demonstrated that using a CZTS electrolyte with a concentration of 0.2 M trisodium citrate yields CZTS thin films with an electronic bandgap of 1.52 eV, a p-type nature, and good uniformity, which are all results desired for the fabrication of thin film solar cells. Characterization was performed using UV-Vi-IR optical absorption, SEM imaging, Raman spectrometry, and photoelectrochemical cells conducted for electronic bandgap, morphology, chemical composition, and semiconductor conductivity, respectively.
Swelling Behavior of Polyacrylamide Hydrogels near Phase Transition  [PDF]
R. R. Janot Pacheco, M. E. S. R. Silva, R. G. Sousa, R. F. S. Freitas
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.58063
Abstract:
Hydrogels based on acrylamide (AA) and sodium methacrylate (NMA) as ionic monomer were prepared by solution polymerization using N,N’-methylenebis(acrylamide) (MBA) or ethylene glycol dimethacrylate (EGMA) as crosslinkers and Ammonium Persulfate (APS) and N,N,N’,N’-Te-tramethyl-ethylenediamine (TMEDA) as initiators. Swelling behavior was greatly affected by NMA content near phase transition. Increasing ionic monomer concentration compared to total monomer one led to high expansion in water, oscillating around 285 g/g for MBA and 325 g/g for EGMA crosslinker, above 20% of NMA. Dynamic Light Scattering experiments were performed and, for both crosslinkers, the dynamic correlation length (ξ) decreased with increasing NMA content, contributing to diminish hydrogels spatial inhomogeneities.
Copulation of Opisthogonimus fonsecai Ruiz & Le?o, 1942 (Trematoda, Digenea, Plagiorchiidae), parasite of Bothrops moojeni Hoge, 1966 (Serpentes, Viperidae)
Silva, R. J.;
Journal of Venomous Animals and Toxins including Tropical Diseases , 2005, DOI: 10.1590/S1678-91992005000100008
Abstract: copulation in opisthogonimus fonsecai ruiz & le?o, 1942 (trematoda, digenea, plagiorchiidae), parasite of bothrops moojeni hoge, 1966 (serpentes, viperiade), was reported. data on the histology of the cirrus and metraterm of the copulants were presented. morphology of the cirrus was also examined by scanning electron microscopy.
Diet and feeding activity of Acestrorhynchus lacustris (Lütken, 1875) (Characiformes, Acestrorhynchidae) in the water reservoir at Ribeir?o Claro, SP
Silva, AT.;Goitein, R.;
Brazilian Journal of Biology , 2009, DOI: 10.1590/S1519-69842009000400002
Abstract: a. lacustris is a widely distributed species in the s?o francisco and paraná river basins, mainly in lentic waters. specimens were captured monthly, over a whole year in a reservoir built by damming the ribeir?o claro stream (sp). the stomach contents analyses showed a predominantly piscivorous diet. feeding activity showed to be clearly less intense during winter, when all the sampling groups were compared. despite the fact that the diet of a. lacustris presents a high diversity of prey-species, the prey size, their abundance and also behavior possibly determined a certain preference for some of them.
Assessment of body surface temperature in cetaceans: an iterative approach
Silva, R. G.;
Brazilian Journal of Biology , 2004, DOI: 10.1590/S1519-69842004000400021
Abstract: heat transfer from skin surface to ambient water is probably the most important aspect of thermal balance in marine mammals, but the respective calculations depend on knowing the surface temperature (ts), the direct measurement of which in free animals is very difficult. an indirect iterative method is proposed for ts prediction in free cetaceans from deep body temperature, swimming speed, and temperature and thermodynamic properties of the water.
Cosmological constant and polymer physics
Silva, P. R.;
Brazilian Journal of Physics , 2008, DOI: 10.1590/S0103-97332008000500010
Abstract: it is traced out a parallel between the cosmological constant problem and the polymer physics. the time evolution of the universe world line is compared with the growing of a polymer chain. an equivalent flory free energy and a modification of it are used as a means to evaluate two versions for the "radius of gyration" of the universe. it is proposed a link between this radius of gyration and the cosmological constant parameter.
Intera??o forte e eletromagnetismo
Silva, P.R.;
Revista Brasileira de Ensino de Física , 2008, DOI: 10.1590/S1806-11172008005000005
Abstract: the basic structure of the classical electromagnetism is used as a means to study the strong interaction. the strong coupling constant and the strong field (expessed in terms of an equivalent electric field) inside the nucleon (proton or neutron) are estimated. it is also evaluated the vacuum pressure on the boundary of the nucleon. quark confinement is briefly discussed. simplified versions of the mit bag model are also considered in the present treatment.
Page 1 /269211
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.