Browsing by Author "Tawfik, A."

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Calibrated fair measure of particle physics publications: indices to quantify an individual's scientific research output
(CANADIAN SCIENCE PUBLISHING, 2015) Tawfik, A.
Do existing ways of measuring scientific quality reflect the disadvantages of not being part of giant collaborations? How could possible discrimination be avoided? We propose indices defined for each discipline (subfield) and which count the plausible contributions added up by collaborators, while maintaining the spirit of interdependency. Based on the growing debate about defining potential biases and detecting unethical behavior, a standardized method to measure contributions of the astronomical number of co-authors is introduced.
Cosmological Consequences of QCD Phase Transition(s) in Early Universe
(AMER INST PHYSICS, 2009) Tawfik, A.
We discuss the cosmological consequences of QCD phase transition(s) on the early universe. We argue that our recent knowledge about the transport properties of quark-gluon plasma (QGP) should thraw additional lights on the actual time evolution of our universe. Understanding the nature of QCD phase transition(s), which can be studied in lattice gauge theory and verified in heavy ion experiments, provides an explanation for cosmological phenomenon stem from early universe.
Dynamical fluctuations in baryon-meson ratios
(IOP PUBLISHING, 2013) Tawfik, A.
The event-by-event dynamical fluctuations in kaon-proton and proton-pion ratios have been studied as a function of the center-of-mass energies of nucleon-nucleon collisions root s. Based on the changing phase space volume which apparently is the consequence of the phase transition(s) from hadrons to a quark-gluon plasma at large root s, the single-particle distribution function f is assumed to be modified. Varying f and the phase space volume are implemented in the grand-canonical ensemble, especially at root s > 17 GeV, so that the hadron resonance gas model, when taking into account the experimental acceptance A and the quark phase space occupation factor gamma, turns out to be able to reproduce the dynamical fluctuations in (K+ + K-)/(p + (p) over bar) and (p + (p) over bar)/(pi(+) + pi(-)) ratios over the entire range of root s. It seems that the applied thermodynamic statistics could come up with a new modification to the Tsallis statistics. Both non-extensivity and changing the phase space are suggested and utilized in the present work.
Emergence of cosmic space and minimal length in quantum gravity: a large class of spacetimes, equations of state, and minimal length approaches
(INDIAN ASSOC CULTIVATION SCIENCE, 2016) Tawfik, A.; Diab, A.
We argue that the modified Landau-Raychaudhuri equations should first be analysed in a large class of spacetimes and in dependence on various equations of states, before endorsing any conclusion about (non) singular Big Bang. From the corrected entropy-area law in a large class of metrics, the generalized uncertainty principle (GUP) and the modified dispersion relation (MDR) approaches, and various equations of states, the modified Friedmann equations are derived. They are applied on Landau-Raychaudhuri equations in emergence of cosmic space framework from fixed point method. We show that any conclusion about (non) singular Big Bang is simply badly model-dependent, especially when utilizing GUP and MDR approaches, which can not replace a good theory for quantum gravity. We conclude that the various quantum gravity approaches, metrics and equations of state lead to different modifications in Friedmann and Landau-Raychaudhuri equations and thus to different (non) singular solutions for Big Bang theory.
Enhancement of piezoelectric properties for [poly (vinylidene fluoride)/barium zirconate titanate] nanocomposites
(SPRINGER, 2017) Hemeda, O.M; Tawfik, A.; El-Shahawy, M.M.; Darwish, K.A.
Poly (vinylidene fluoride) / barium zirconate titanate nanocomposite samples with the formula [x (PVDF) / (1 - x) BZT] (where x = zero, 0.2, 0.4, 0.6, 0.8 and 1) are prepared using the hot pressing method. The BZT is prepared using the tartrate precursor method. The properties of these nanocomposites are characterized by X-ray diffraction (XRD), scan electron microscope (SEM), transmission electron microscope (TEM) and Fourier transformed infrared (FTIR) at room temperature. The XRD patterns indicate that the average crystallite size ranges from 7.5 to 23.8 nm. The grain size is estimated from SEM micrograph and lies between 263 and 186 nm, whereas the average crystallite size has a distribution between 14 and 70nm from TEM images. The FTIR spectra illustrate the absence of any absorption band related to the (gamma) phase, but the absorption bands characteristic for (alpha), and (beta) phases of PVDF are observed. The fraction of the (beta) phase of PVDF increases by increasing the BZT content, which is very useful in industrial applications, such as sensors, actuators and transducers. The high value of the piezoelectric coefficient d(33) is measured for the PVDF/BZT nanocomposites
FLRW Cosmology with Horava-Lifshitz Gravity: Impacts of Equations of State
(SPRINGER/PLENUM PUBLISHERS, 2017) Tawfik, A.; Abou El Dahab, E.
Inspired by Lifshitz theory for quantum critical phenomena in condensed matter, Horava proposed a theory for quantum gravity with an anisotropic scaling in ultraviolet. In Horava-Lifshitz gravity (HLG), we have studied the impacts of six types of equations of state on the evolution of various cosmological parameters such as Hubble parameters and scale factor. From the comparison of the general relativity gravity with the HLG with detailed and without with non-detailed balance conditions, remarkable differences are found. Also, a noticeable dependence of singular and non-singular Big Bang on the equations of state is observed. We conclude that HLG explains various epochs in the early universe and might be able to reproduce the entire cosmic history with and without singular Big Bang.
Sort-Mid tasks scheduling algorithm in grid computing
(ELSEVIER, 2015) Reda, Naglaa M.; Tawfik, A.; Marzok, Mohamed A.; Khamis, Soheir M.
Scheduling tasks on heterogeneous resources distributed over a grid computing system is an NP-complete problem. The main aim for several researchers is to develop variant scheduling algorithms for achieving optimality, and they have shown a good performance for tasks scheduling regarding resources selection. However, using of the full power of resources is still a challenge. In this paper, a new heuristic algorithm called Sort-Mid is proposed. It aims to maximizing the utilization and minimizing the makespan. The new strategy of Sort-Mid algorithm is to find appropriate resources. The base step is to get the average value via sorting list of completion time of each task. Then, the maximum average is obtained. Finally, the task has the maximum average is allocated to the machine that has the minimum completion time. The allocated task is deleted and then, these steps are repeated until all tasks are allocated. Experimental tests show that the proposed algorithm outperforms almost other algorithms in terms of resources utilization and makespan. (C) 2014 Production and hosting by Elsevier B.V. on behalf of Cairo University.