Charged perfect fluid stellar structures with Bardeen model

2020 ◽  
Vol 35 (18) ◽  
pp. 2050083 ◽  
Author(s):  
M. Farasat Shamir ◽  
G. Mustafa ◽  
Quresha Hanif
Keyword(s):  
Electric Field ◽  
Perfect Fluid ◽  
Maxwell Equations ◽  
Graphical Analysis ◽  
Physical Parameters ◽  
Symmetric Model ◽  
Speed Of Light ◽  
Suitable Form ◽  
Model Geometry ◽  
Spherically Symmetric Model

This paper is devoted to study static spherically symmetric model in the presence of charged perfect fluid. This is the generalization of neutral perfect fluid (when there is no charge) through the solution of Einstein Maxwell equations. For this purpose, we consider a suitable form of gravitational potential [Formula: see text] and the electric field [Formula: see text], already used in the literature. The value of mass-radius ratio or compactness [Formula: see text], which depends upon the chosen model exceeds the value [Formula: see text] corresponding to neutral stars. The most important feature of the current study is to use the Bardeen model geometry instead of usual Reissner–Nordström model for the matching conditions. In this case the energy density and pressure remain positive, bounded and monotonically decreasing whereas electric field is monotonically increasing. Also the causality condition, i.e. the magnitude of speed of sound must be less than the speed of light, is satisfied. Moreover, the behavior of all the physical parameters at the center and on surface of star of mass [Formula: see text] and for Her X-1 are tabulated. All the results by graphical analysis and tabular information suggest that Bardeen model provides physically realistic stellar structures.

scholarly journals A charged perfect fluid model with high compactness

2019 ◽  
Vol 65 (4 Jul-Aug) ◽  
pp. 382 ◽  
Author(s):  
G. Estevez-Delgado ◽  
J. Estevez-Delgado ◽  
M. Pineda Duran ◽  
N. Montelongo García ◽  
J.M. Paulin-Fuentes
Keyword(s):  
Electric Field ◽  
Perfect Fluid ◽  
Maxwell Equations ◽  
Fluid Model ◽  
Stellar Model ◽  
Compact Stars ◽  
Charged Fluid ◽  
Charge Parameter ◽  
Positive Functions ◽  
Increasing Function

A relativistic, static and spherically symmetrical stellar model is presented, constituted by a perfect charged fluid. This represents a generalization to the case of a perfect neutral fluid, whose construction is made through the solution to the Einstein-Maxwell equations proposing a form of gravitational potential  $g_{tt}$ and the electric field. The choice of electric field implies that this model supports values of compactness$u=GM/c^2R\leq 0.5337972212$, values higher than the case without electric charge ($u\leq 0.3581350065$), being this feature of relevance to get to represent compact stars. In addition, density and pressure are positive functions, bounded and decreasing monotones, the electric field is a monotonously increasing function as well as satisfying the condition of causality so the model is physically acceptable. In a complementary way, the internal behavior of the hydrostatic functions and their values are obtained taking as a data the corresponding to a star of $1 M_\odot$,for different values of the charge parameter, obtaining an interval for the central density $\rho_c\approx (7.9545,2.7279) 10^{19}$ $ Kg/m^3$ characteristic of compact stars.

Factors Controlling Electropermeabilisation of Cell Membranes

2002 ◽  
Vol 1 (5) ◽  
pp. 319-327 ◽  
Author(s):  
M. P. Rols ◽  
M. Golzio ◽  
B. Gabriel ◽  
J. Teissié
Keyword(s):  
Cell Surface ◽  
Electric Field ◽  
Pulse Duration ◽  
Cell Membranes ◽  
Physical Parameters ◽  
Local Exchange ◽  
Physical Mechanisms ◽  
A Cell

Electric field pulses are a new approach for drug and gene delivery for cancer therapy. They induce a localized structural alteration of cell membranes. The associated physical mechanisms are well explained and can be safely controlled. A position dependent modulation of the membrane potential difference is induced when an electric field is applied to a cell. Electric field pulses with an overcritical intensity evoke a local membrane alteration. A free exchange of hydrophilic low molecular weight molecules takes place across the membrane. A leakage of cytosolic metabolites and a loading of polar drugs into the cytoplasm are obtained. The fraction of the cell surface which is competent for exchange is a function of the field intensity. The level of local exchange is strongly controlled by the pulse duration and the number of successive pulses. The permeabilised state is long lived. Its lifetime is under the control of the cumulated pulse duration. Cell viability can be preserved. Gene transfer is obtained but its mechanism is not a free diffusion. Plasmids are electrophoretically accumulated against the permeabilised cell surface and form aggregates due to the field effect. After the pulses, several steps follow: translocation to the cytoplasm, traffic to the nucleus and expression. Molecular structural and metabolic changes in cells remain mostly poorly understood. Nevertheless, while most studies were established on cells in culture ( in vitro), recent experiments show that similar effects are obtained on tissue ( in vivo). Transfer remains controlled by the physical parameters of the electrical treatment.

Numerical study of electric field effects on the deformation of two-dimensional liquid drops in simple shear flow at arbitrary Reynolds number

2009 ◽  
Vol 626 ◽  
pp. 367-393 ◽  
Author(s):  
STEFAN MÄHLMANN ◽  
DEMETRIOS T. PAPAGEORGIOU
Keyword(s):  
Steady State ◽  
Shear Flow ◽  
Electric Field ◽  
Electric Fields ◽  
Simple Shear ◽  
Simple Shear Flow ◽  
Physical Parameters ◽  
Shear Stresses ◽  
Two Dimensional ◽  
Liquid Drops

The effect of an electric field on a periodic array of two-dimensional liquid drops suspended in simple shear flow is studied numerically. The shear is produced by moving the parallel walls of the channel containing the fluids at equal speeds but in opposite directions and an electric field is generated by imposing a constant voltage difference across the channel walls. The level set method is adapted to electrohydrodynamics problems that include a background flow in order to compute the effects of permittivity and conductivity differences between the two phases on the dynamics and drop configurations. The electric field introduces additional interfacial stresses at the drop interface and we perform extensive computations to assess the combined effects of electric fields, surface tension and inertia. Our computations for perfect dielectric systems indicate that the electric field increases the drop deformation to generate elongated drops at steady state, and at the same time alters the drop orientation by increasing alignment with the vertical, which is the direction of the underlying electric field. These phenomena are observed for a range of values of Reynolds and capillary numbers. Computations using the leaky dielectric model also indicate that for certain combinations of electric properties the drop can undergo enhanced alignment with the vertical or the horizontal, as compared to perfect dielectric systems. For cases of enhanced elongation and alignment with the vertical, the flow positions the droplets closer to the channel walls where they cause larger wall shear stresses. We also establish that a sufficiently strong electric field can be used to destabilize the flow in the sense that steady-state droplets that can exist in its absence for a set of physical parameters, become increasingly and indefinitely elongated until additional mechanisms can lead to rupture. It is suggested that electric fields can be used to enhance such phenomena.

SOLITARY WAVES OF THE NONLINEAR KLEIN-GORDON EQUATION COUPLED WITH THE MAXWELL EQUATIONS

2002 ◽  
Vol 14 (04) ◽  
pp. 409-420 ◽  
Author(s):  
VIERI BENCI ◽  
DONATO FORTUNATO FORTUNATO
Keyword(s):  
Electromagnetic Field ◽  
Solitary Wave ◽  
Electric Field ◽  
Solitary Waves ◽  
Maxwell Equations ◽  
Gordon Equation ◽  
Klein Gordon ◽  
Klein Gordon Equation

This paper is divided in two parts. In the first part we construct a model which describes solitary waves of the nonlinear Klein-Gordon equation interacting with the electromagnetic field. In the second part we study the electrostatic case. We prove the existence of infinitely many pairs (ψ, E), where ψ is a solitary wave for the nonlinear Klein-Gordon equation and E is the electric field related to ψ.

Seismic energy efficiency of underground nuclear detonations

1969 ◽  
Vol 59 (6) ◽  
pp. 2311-2323
Author(s):  
R. A. Mueller
Keyword(s):  
Energy Efficiency ◽  
Elastic Waves ◽  
Energy Equation ◽  
Seismic Energy ◽  
Symmetric Model ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Field Radiation ◽  
Radiation Zone ◽  
Spherically Symmetric Model

abstract The amount of energy going into the formation of elastic waves in the far field radiation zone was determined for the underground nuclear explosions Boxcar, Benham, Salmon, Schooner, Shoal and Sterling. The method is based on Sharpe's spherically symmetric model. The analytical solution of Sharpe's problem is developed into an energy equation and applied to the experimental results. The results obtained in this manner are in the same range found by other investigators. A basic conclusion is that seismic energy efficiency appears to be significantly lower for cratering events than for contained events.

scholarly journals An interior solution with perfect fluid

2020 ◽  
Vol 35 (17) ◽  
pp. 2050141 ◽  
Author(s):  
Joaquin Estevez-Delgado ◽  
Jose Vega Cabrera ◽  
Joel Arturo Rodriguez Ceballos ◽  
Arthur Cleary-Balderas ◽  
Mauricio Paulin-Fuentes
Keyword(s):  
Perfect Fluid ◽  
Speed Of Sound ◽  
Numerical Data ◽  
Index Formula ◽  
Interior Solution ◽  
Radial Coordinate ◽  
Speed Of Light ◽  
Bounded Functions ◽  
The Stability ◽  
Stability Of The Solution

Starting from the construction of a solution for Einstein’s equations with a perfect fluid for a static spherically symmetric spacetime, we present a model for stars with a compactness rate of [Formula: see text]. The model is physically acceptable, that is to say, its geometry is non-singular and does not have an event horizon, pressure and speed of sound are bounded functions, positive and monotonically decreasing as function of the radial coordinate, also the speed of sound is lower than the speed of light. While it is shown that the adiabatic index [Formula: see text], which guarantees the stability of the solution. In a complementary manner, numerical data are presented considering the star PSR J0737-3039A with observational mass of [Formula: see text], for the value of compactness [Formula: see text], which implies the radius [Formula: see text] and the range of the density [Formula: see text] [Formula: see text], where [Formula: see text] and [Formula: see text] are the central density and the surface density, respectively. This range is consistent with the expected values; as such, the model presented allows to describe this type of stars.

MØLLER ENERGY–MOMENTUM COMPLEX FOR HIGHER-DIMENSIONAL SPHERICALLY SYMMETRIC SPACETIME IN GENERAL RELATIVITY

2012 ◽  
Vol 27 (40) ◽  
pp. 1250231 ◽  
Author(s):  
HÜSNÜ BAYSAL
Keyword(s):  
General Relativity ◽  
Momentum Density ◽  
Momentum Tensor ◽  
Symmetric Model ◽  
Spherically Symmetric ◽  
Higher Dimensional ◽  
Energy And Momentum ◽  
Momentum Complex ◽  
Spherically Symmetric Metric ◽  
Spherically Symmetric Model

We have calculated the total energy–momentum distribution associated with (n+2)-dimensional spherically symmetric model of the universe by using the Møller energy–momentum definition in general relativity (GR). We have found that components of Møller energy and momentum tensor for given spacetimes are different from zero. Also, we are able to get energy and momentum density of various well-known wormholes and black hole models by using the (n+2)-dimensional spherically symmetric metric. Also, our results have been discussed and compared with the results for four-dimensional spacetimes in literature.

Effect of Contaminant Flow-rate and Applied Voltage on the Current Density and Electric Field of Polymer Tracking Test

2016 ◽  
Vol 6 (2) ◽  
pp. 819
Author(s):  
F. L. Muhamedin ◽  
M. A. M. Piah ◽  
N. A. Othman ◽  
Nasir Ahmed Algeelani
Keyword(s):  
Electric Field ◽  
Flow Rate ◽  
Current Density ◽  
Applied Voltage ◽  
Fem Simulation ◽  
Surface Discharge ◽  
Physical Parameters ◽  
Insulation Material ◽  
Material Degradation ◽  
Contaminant Flow

<p>Electrical failure due to surface discharge on the insulation material will cause material degradation and eventually lead to system failure. The flow of leakage current (LC) on the insulator surface under wet contamination is used to determine the material degradation level. According to IEC 60587 standard, LC exceeding 60 mA for more than two seconds is considered as failure. In this study, the  electric field and current density distributions on the linear low-density polyethylene (LLDPE) and natural rubber blend material have been analyzed using finite element method (FEM) analysis. The physical parameters used in FEM simulation were applied with voltage and contaminant flow rate, in accordance to contaminant conductivity. Tracking test condition according to IEC 60587 standard has been applied as proposed by the reference work in simulation using QuickField FEM software. The results show that the electric field and current density would become critical in higher applied voltage and contaminant flow rate. The highest average and highest maximum current density and electric field are found in both applied voltage of 6 kV and contaminant flow rate of 0.90 mlmin<sup>-1</sup>.</p>

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