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Bijalwan N.,Freelancer
Astrophysics and Space Science | Year: 2012

We show in this article that charged fluid with pressure derived by Bijalwan (Astrophys. Space. Sci. doi:10. 1007/s10509-011-0691-0, 2011a) can be used to model classical electron, quark, neutron stars and pulsar with charge matter, quasi black hole, white dwarf, super-dense star etc. Recent analysis by Bijalwan (Astrophys. Space. Sci., 2011d) that all charged fluid solutions in terms of pressure mimic the classical electron model are partially correct because solutions by Bijalwan (Astrophys. Space. Sci. doi:10. 1007/s10509-011-0691-0, 2011a) may possess a neutral counterpart. In this paper we characterized solutions in terms of pressure for charged fluids that have and do not have a well behaved neutral counter part considering same spatial component of metric e λ for neutral and charged fluids. We discussed solution by Gupta and Maurya (Astrophys. Space Sci. 331(1):135-144, 2010a) and solutions by Bijalwan (Astrophys. Space Sci. doi:10. 1007/s10509-011-0735-5, 2011b; Astrophys. Space Sci. doi:10. 1007/s10509-011-0780-0, 2011c; Astrophys. Space Sci., 2011d) such that charged fluids possess and do not possess a neutral counterpart as special cases, respectively. For brevity, we only present some analytical results in this paper. © 2011 Springer Science+Business Media B.V. Source


Bijalwan N.,Freelancer | Gupta Y.K.,Indian Institute of Technology Roorkee
Astrophysics and Space Science | Year: 2012

In the present article models of well behaved charged superdense stars with surface density 2×10 14 gm/cm 3 are constructed by considering a static spherically symmetric metric with t = const hypersurfaces as spheroids and hyperboloids. Maximum mass of the star is found to be 7. 66300M Θ with radius 19. 35409 km for spheroids case while 1. 51360M Θ with radius 13. 72109 km for hyperboloid case satisfying ultra-relativistic conditions. The solutions thus found satisfy all the reality and causality conditions. For brevity we don't present a detailed analysis of the derived solutions in this paper. © 2011 Springer Science+Business Media B.V. Source


Madjdi F.,Freelancer | Husig S.,University of Regensburg
Telecommunications Policy | Year: 2011

This paper examines how three incumbent mobile network operators (MNOs) in Germany responded in terms of their strategy to the emergence of the wireless local area network (W-LAN) technology and how they interpreted this potentially disruptive technology in their own strategic context. Additionally, prior empirical results and forecasts on the limited disruptive potential of W-LAN for the German MNOs lacked persuasive firm-level evidence to distinguish the real reason for the presented observations and analysis. So far it was unclear whether the observations were caused by successful response strategies of incumbent MNOs or by the inherent limited disruptive potential of the W-LAN technology. For this purpose case studies of three major MNOs in Germany were performed to assess and compare their respective response strategies. Using the theoretical framework of disruptive technology, the results were evaluated in a cross-case analysis to study how these firms interpreted and reacted to the potential disruptiveness of W-LAN. The results indicate significant differences for the respective MNOs between their perception of W-LAN as a potential disruptive technology, their strategic development processes inside the organisation to understand the potential impact of W-LAN on their respective business model, and to enforce an appropriate response strategy and structural implementation. This incumbent heterogeneity depends primarily on their idiosyncratic strategic and structural context. These findings reveal that the incumbent MNOs in Germany were aware of the disruptive technology concept but did not react in a theory-conform way. However, since W-LAN had a sustaining impact on the MNOs and their response strategies followed sustaining reaction patterns, earlier studies, which show a limited disruptive potential of W-LAN for the German MNOs, are supported. © 2011 Elsevier Ltd. All rights reserved. Source


Bijalwan N.,Freelancer
International Journal of Theoretical Physics | Year: 2012

General exact higher-dimensional (n+2), n > 2 solutions in general theory of relativity of Einstein-Maxwell field equations for spherically symmetric distribution of charged pressure perfect fluid are expressed in terms of pressure extending 4-dimensional solutions presented by Bijalwan (Astrophys. Space Sci. 2011, doi:10.1007/s10509-011-0691-0). Subsequently, metrics (eλ and eυ), matter density and electric intensity are expressible in terms of pressure. Consequently, Pressure is found to be an invertible arbitrary function of ω (=c1+c2r2), where c1 and c2 (≠0) are arbitrary constants, and r is the radius of star, i. e. p=p(ω). We present a general solution for charged pressure fluid in terms for ω. We list and discuss some old and new solutions which fall in this category. Also, these solutions satisfy barotropic equation of state relating the radial pressure to the energy density. But we noticed that none of these solutions in terms of pressure for charged fluids has a well behaved neutral counter part for a spatial component of metric eλ i. e. choosing same spatial component for charged and neutral fluid. To illustrate the approach, we discovered a new solution for extended charged analogues of Schwarzschild interior solution in higher dimensions which is found to be well behaved only for n=2. The maximum mass found to be 1. 512 MΘ with linear dimension 14. 964 km. Physical quantities pressure, energy density, red-shift, velocity of sound and p/c2ρ are well behaved and monotonically decreasing towards the surface while adiabatic index and charge density are monotonically increasing. For brevity we don't discuss the numerical results in detailed. © 2011 Springer Science+Business Media, LLC. Source


Bijalwan N.,Freelancer
Astrophysics and Space Science | Year: 2011

Recently, Bijalwan (Astrophys. Space Sci., doi: 10.1007/s10509-011-0691-0, 2011a) discussed charged fluid spheres with pressure while Bijalwan and Gupta (Astrophys. Space Sci. 317, 251-260, 2008) suggested using a monotonically decreasing function f{hook} to generate all possible physically viable charged analogues of Schwarzschild interior solutions analytically. They discussed some previously known and new solutions for Schwarzschild parameter, a being radius of star. In this paper we investigate wide range of u by generating a class of solutions that are well behaved and suitable for modeling Neutron star charge matter. We have exploited the range u≤0.142 by considering pressure p=p(ω) and, where to explore new class of solutions. Hence, class of charged analogues of Schwarzschild interior is found for barotropic equation of state relating the radial pressure to the energy density. The analytical models thus found are well behaved with surface red shift zs≤0. 181, central red shift zc≤0.282, mass to radius ratio M/a≤0.149, total charge to total mass ratio e/M≤0.807 and satisfy Andreasson's (Commun. Math. Phys. 288, 715-730, 2009) stability condition. Red-shift, velocity of sound and p/c2ρ are monotonically decreasing towards the surface while adiabatic index is monotonically increasing. The maximum mass found to be 1.512 MΘ with linear dimension 14.964 km. Class of charged analogues of Schwarzschild interior discussed in this paper doesn't have neutral counter part. These solutions completely describe interior of a stable Neutron star charge matter since at centre the charge distribution is zero, e/M≤0.807 and a typical neutral Neutron star has mass between 1.35 and about 2.1 solar mass, with a corresponding radius of about 12 km (Kiziltan et al., arXiv:1011.4291 [astro-ph. GA], 2010). © 2011 Springer Science+Business Media B.V. Source

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