Kinematic Self-Similar Plane Symmetric Solutions

This paper is devoted to classify the most general plane symmetric spacetimes according to kinematic self-similar perfect fluid and dust solutions. We provide a classification of the kinematic self-similarity of the first, second, zeroth and infinite kinds with different equations of state, where the self-similar vector is not only tilted but also orthogonal and parallel to the fluid flow. This scheme of classification yields twenty four plane symmetric kinematic self-similar solutions. Some of these solutions turn out to be vacuum. These solutions can be matched with the already classified plane symmetric solutions under particular coordinate transformations. As a result, these reduce to sixteen independent plane symmetric kinematic self-similar solutions.Comment: 29 pages, accepted for publication in Classical Quantum Gravit

Spherically Symmetric Gravitational Collapse

In this paper, we discuss gravitational collapse of spherically symmetric spacetimes. We derive a general formalism by taking two arbitrary spherically symmetric spacetimes with $g_{00}=1$. Israel's junction conditions are used to develop this formalism. The formulae for extrinsic curvature tensor are obtained. The general form of the surface energy-momentum tensor depending on extrinsic curvature tensor components is derived. This leads us to the surface energy density and the tangential pressure. The formalism is applied to two known spherically symmetric spacetimes. The results obtained show the regions for the collapse and expansion of the shell.Comment: 12 pages, 4 figures, accepted for publication in Mod. Phys. Lett.

E-government evaluation: Reflections on three organisational case studies

The deployment of e-Government continues at a significant cost and pace in the worldwide public sector. An important area of research is that of the evaluation of e-Government. In this paper the authors report the findings from three interpretive in-depth organisational case studies that explore e-Government evaluation within UK public sector settings. The paper elicits insights to organisational and managerial aspects with the aim of improving knowledge and understanding of e- Government evaluation. The findings that are extrapolated from the analysis of the three case studies are classified and mapped onto a tentative e-Government evaluation framework and presented in terms lessons learnt. These aim to inform theory and improve e- Government evaluation practice. The paper concludes that e-Government evaluation is an under developed area and calls for senior executives to engage more with the e- Government agenda and commission e-Government evaluation exercises to improve evaluation practice

E-Government Evaluation: Reflections on two Organisational studies

Senior executives in public sector organisations have been charged with delivering an e-Government agenda. A key emerging area of research is that of the evaluation of e-Government, given that economic factors have traditionally dominated any traditional ICT evaluation process. In this paper the authors report the findings from two interpretive in-depth case studies in the UK public sector, which explore e-Government organisational evaluation within a public sector setting. This paper seeks to offer insights to organisational and managerial aspects surrounding the improvement of knowledge and understanding of e-Government evaluation. The findings that are elicited from the case studies are analysed and presented in terms of a framework derived from organisational analysis to improve e-Government evaluation, with key lessons learnt being extrapolated from practice. The paper concludes that e-Government evaluation is both an under developed and under managed area, and calls for senior executives to engage more with the e-Government agenda and for organisations to review e-Government evaluation to improve evaluation practice

Phantom Energy Accretion by Stringy Charged Black Hole

We investigate the dynamical behavior of phantom energy near stringy magnetically charged black hole. For this purpose, we derive equations of motion for steady-state spherically symmetric flow of phantom energy onto the stringy magnetically charged black hole. It is found that phantom energy accreting onto black hole decreases its mass. Further, the location of critical points of accretion is explored, which yields mass to charge ratio. This ratio implies that accretion process cannot transform a black hole into an extremal black hole or a naked singularity, hence cosmic censorship hypothesis remains valid here.Comment: 7 pages, no figur

Energy-Momentum Distribution: A Crucial Problem in General Relativity

This paper is aimed to elaborate the problem of energy-momentum in General Relativity. In this connection, we use the prescriptions of Einstein, Landau-Lifshitz, Papapetrou and M\"{o}ller to compute the energy-momentum densities for two exact solutions of Einstein field equations. The spacetimes under consideration are the non-null Einstein-Maxwell solutions and the singularity-free cosmological model. The electromagnetic generalization of the G\"{o}del solution and the G\"{o}del metric become special cases of the non-null Einstein-Maxwell solutions. It turns out that these prescriptions do not provide consistent results for any of these spacetimes. These inconsistence results verify the well-known proposal that the idea of localization does not follow the lines of pseudo-tensorial construction but instead follows from the energy-momentum tensor itself. These differences can also be understood with the help of the Hamiltonian approach.Comment: 28 pages, accepted for publication in Int. J. Mod. Phys.

A supplier selection strategy within the Malaysian telecommunications industry

The telecommunication industry in Malaysia has grown rapidly over the last 15 years, with effective supply chain management becoming increasing important within the sector. A multitude of providers and part owned Malaysian government companies, vendors and suppliers are involved in generating and creating value-adding products and services within this sector (across wireless, wireline, broadband business and consumer lines of business). This paper describes key challenges facing a major telecoms service provider in Malaysia with regards to drivers involved in the overall procurement and supplier selection with regards to components of performance management, decision-making, selection techniques, quality and cost management, procurement policy and procurement ethics. This paper further focuses on defining and detailing research currently being undertaken to develop a framework for identifying supplier selection drivers that are inherent within the sector and suggests a research approach to investigate and develop strategies for supplier selection for the telecommunications industry in Malaysia

Charged Perfect Fluid Cylindrical Gravitational Collapse

This paper is devoted to study the charged perfect fluid cylindrical gravitational collapse. For this purpose, we find a new analytical solution of the field equations for non-static cylindrically symmetric spacetime. We discuss physical properties of the solution which predict gravitational collapse. It is concluded that in the presence of electromagnetic field the outgoing gravitational waves are absent. Further, it turns out that when longitudinal length reduces to zero due to resultant action of gravity and electromagnetic field, then the end state of the gravitational collapse is a conical singularity. We also explore the smooth matching of the collapsing cylindrical solution to a static cylindrically symmetric solution. In this matching, we take a special choice of constant radius of the boundary surface. We conclude that the gravitational and Coulomb forces of the system balance each other.Comment: 17 pages, 4 figures, accepted for publication in J. Phys. Soc. Jp

Blockchain Vulnerabilities and Recent Security Challenges: A Review Paper

Blockchain is a relatively new technology, a distributed database used for sharing between nodes of computer networks. A blockchain stores all information in automated digital format as a database. Blockchain innovation ensures the accuracy and security of the data record and generates trust without the need for a trusted third party. The objectives of this paper are to determine the security risk of the blockchain systems, analyze the vulnerabilities exploited on the blockchain, and identify recent security challenges that the blockchain faces. This review paper presents some of the previous studies of the security threats that blockchain faces and reviews the security enhancement solutions for blockchain vulnerabilities. There are some studies on blockchain security issues, but there is no systematic examination of the problem, despite the blockchain system’s security threats. An observational research methodology was used in this research. Through this methodology, many research related to blockchain threats and vulnerabilities obtained. The outcomes of this research are to Identify the most important security threats faced by the blockchain and consideration of security recently vulnerabilities. Processes and methods for dealing with security concerns are examined. Intelligent corporate security academic challenges and limitations are covered throughout this review. The goal of this review is to serve as a platform as well as a reference point for future work on blockchain-based security

Dealing with propositional ambiguity in business process improvement

If it is true that people express their views about organisational issues in ambiguous terms then one needs to address this ambiguity instead of the ‘problems’ to find an appropriate methodological approach to resolving or dissolving problem situations in the organisation. This paper highlights and discusses those issues, which therefore relate to ambiguityin relation to decision making tasks within organisations, and the related Soft Systems Methodology / Systems Thinking school of thought, which traditionally constrains such ambiguities. A model of these issues is presented in terms of the Business Process Improvement (BPI) task to highlight these interdependencies