844 research outputs found
New Schwarzschild-like solutions in f(T) gravity through Noether symmetries
Spherically symmetric solutions for f(T) gravity models are derived by the so
called Noether Symmetry Approach. First, we present a full set of Noether
symmetries for some minisuperspace models. Then, we compute analytical
solutions and find that spherically symmetric solutions in f(T) gravity can be
recast in terms of Schwarzschild-like solutions modified by a distortion
function depending on a characteristic radius. The obtained solutions are more
general than those obtained by the usual solution methods.Comment: 10 pages, to appear in Phys. Rev.
Quantum cosmology of 5D non-compactified Kaluza-Klein theory
We study the quantum cosmology of a five dimensional non-compactified
Kaluza-Klein theory where the 4D metric depends on the fifth coordinate,
. This model is effectively equivalent to a 4D non-minimally
coupled dilaton field in addition to matter generated on hypersurfaces
l=constant by the extra coordinate dependence in the four-dimensional metric.
We show that the Vilenkin wave function of the universe is more convenient for
this model as it predicts a new-born 4D universe on the constant
hypersurface.Comment: 14 pages, LaTe
Introducing box-plate beam-to-column moment connections
Nowadays, using high-ductility structures in the construction and use of significant buildings is highly appreciated. To use more ductile structures, effort has been made in this research to introduce box-plate beam-to-column connections. They underwent hysteretic loading and it was found from their moment-rotation curves that the bending capacity and ductility of the box-plate connection were more than ordinary rigid connection, and those of the latter were more than those of the normal typical one. It was also shown that stress concentration in box-plate connections disappears over the top and bottom flange plates
Correspondence between Jordan-Einstein frames and Palatini-metric formalisms
We discuss the conformal symmetry between Jordan and Einstein frames
considering their relations with the metric and Palatini formalisms for
modified gravity. Appropriate conformal transformations are taken into account
leading to the evident connection between the gravitational actions in the two
mentioned frames and the Hilbert-Einstein action with a cosmological constant.
We show that the apparent differences between Palatini and metric formalisms
strictly depend on the representation while the number of degrees of freedom is
preserved. This means that the dynamical content of both formalism is
identical.Comment: 6 pages, to appear in Mod. Phys. Lett.
Integrated Treatment of Saline Oily Wastewater Using Sono-Electrokinetic Process, Degradation Mechanism, and Toxicity Assessment
Integration of sonication (US) with electrokinetic (EK) oxidation was studied for the treatment of a saline oily wastewater, as well as the effect of operating parameters, including pH, voltage, electrode distance (ED), sonication power, and reaction time on COD removal. A COD removal of 98 % was observed for the sono-electrokinetic (SEK)
process with an applied voltage of 2.5 V, US power of 300 W, initial COD concentration of 3850 mg Lâ1, and reaction time of 9 h. The efficiency of SEK over sonication alone and EK oxidation alone was also confirmed with a higher pseudo-first-order reaction rate constant of 0.43 hâ1, compared to values of 0.13 and 0.01 for alternative processes. In
addition, the biodegradability of effluent was improved based on average oxidation state (AOS) and carbon oxidation state (COS) analysis. Oxygen consumption rate inhibition, dehydrogenase activity inhibition, and growth rate inhibition methods demonstrated the low toxicity of effluent (12â15 %) compared to influent. The current work indicated that SEK is a reliable and efficient technology for the treatment of saline oily wastewaters containing recalcitrant aromatic organics.
This work is licensed under a Creative Commons Attribution 4.0 International License
Families of exact solutions of a 2D gravity model minimally coupled to electrodynamics
Three families of exact solutions for 2-dimensional gravity minimally coupled
to electrodynamics are obtained in the context of theory. It is
shown, by supersymmetric formalism of quantum mechanics, that the quantum
dynamics of a neutral bosonic particle on static backgrounds with both varying
curvature and electric field is exactly solvable.Comment: 13 pages, LaTeX, to be published in JM
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