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Khan S.A.,Salalah College of Technology
Physics Teacher | Year: 2010

Spherometers are instruments designed to measure the radius of curvature of spherical surfaces.1,2 They are particularly useful in situations where only a portion of the spherical surface is available, for example, for measuring the radii of curvature of spherical lenses.3 A spherometer can be easily modified so that it can also be used to measure the radius of curvature of a right circular cylinder. The resulting device is called a cylindrometer (also known as the cylindrospherometer). The idea is quite old4 but is seldom mentioned in introductory laboratory courses. This paper describes the device and its operation.


Prasad V.R.,Madanapalle Institute of Technology and Science | Gaffar S.A.,Salalah College of Technology | Beg O.A.,Gort Engovation Research
Journal of Thermophysics and Heat Transfer | Year: 2015

Buoyancy-driven laminar free-convection flow, heat, and mass of a non-Newtonian nanofluid from a horizontal circular cylinder to a micropolar fluid have been investigated numerically using an implicit finite difference scheme. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. A nonsimilarity solution is presented that depends on the Prandtl number Pr, Schmidt number Sc, Brownian motion parameter Nb, thermophoresis parameter Nt, material parameter K, and buoyancy ratio parameter N. It is observed that increasing the Brownian motion parameter increases the temperature, Sherwood number, and wall couple stress but decreases the velocity, concentration, angular velocity, skin friction, and Nusselt number. An increase in the thermophoresis parameter is observed to accelerate the velocity, concentration, angular velocity, skin friction, and Nusselt number, whereas it decreases the temperature, the reduced Sherwood number, and wall couple stress. The velocity, angular velocity, Nusselt number, and wall couple stress are reduced with increasing material parameters, whereas the temperature, concentration, skin friction, and Sherwood number are enhanced. It is also observed that increasing material parameters increases velocity, angular velocity, skin friction, Nusselt number, and Sherwood number but decreases temperature, concentration, and wall couple stress. The model finds applications in energy systems and the thermal enhancement of industrial flow processes. Copyright © 2014 by the American Institute of Aeronautics and Astronautics, Inc.


Al-Azzo W.F.,Dhofar University | Al-Azzo W.F.,Salalah College of Technology | Ali B.M.,University Putra Malaysia
World Academy of Science, Engineering and Technology | Year: 2011

This paper addresses the problem of peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. It also introduces a new PAPR reduction technique based on adaptive square-rooting (SQRT) companding process. The SQRT process of the proposed technique changes the statistical characteristics of the OFDM output signals from Rayleigh distribution to Gaussian-like distribution. This change in statistical distribution results changes of both the peak and average power values of OFDM signals, and consequently reduces significantly the PAPR. For the 64QAM OFDM system using 512 subcarriers, up to 6 dB reduction in PAPR was achieved by square-rooting technique with fixed degradation in bit error rate (BER) equal to 3 dB. However, the PAPR is reduced at the expense of only -15 dB out-ofband spectral shoulder re-growth below the in-band signal level. The proposed adaptive SQRT technique is superior in terms of BER performance than the original, non-adaptive, square-rooting technique when the required reduction in PAPR is no more than 5 dB. Also, it provides fixed amount of PAPR reduction in which it is not available in the original SQRT technique.


Ramachandra Prasad V.,Madanapalle Institute of Technology and Science | Gaffar S.A.,Salalah College of Technology | Anwar Beg O.,Gort Engovation Research Aerospace
Journal of Applied Fluid Mechanics | Year: 2016

In this article, we investigate the nonlinear steady boundary layer flow and heat transfer of an incompressible Tangent Hyperbolicnon-Newtonian fluid from a vertical porous plate. The transformed conservation equations are solved numerically subject to physically appropriate boundary conditions using a second-order accurate implicit finite-difference Keller Box technique. The numerical code is validated with previous studies. The influence of a number of emerging non-dimensional parameters, namely the Weissenberg number (We), the power law index (n), Prandtl number (Pr), Biot number (γ), and dimensionless local suction parameter(ξ)on velocity and temperature evolution in the boundary layer regime are examined in detail. Furthermore the effects of these parameters on surface heat transfer rate and local skin friction are also investigated. Validation with earlier Newtonian studies is presented and excellent correlation achieved. It is found that velocity, Skin friction and Nusselt number (heat transfer rate) are reduced with increasing Weissenberg number (We), whereas, temperature is enhanced. Increasing power law index (n) enhances velocity and Nusselt number (heat transfer rate) but temperature and Skin friction decrease. An increase in the Biot number (γ) is observed to enhance velocity, temperature, local skin friction and Nusselt number. An increasing Prandtl number, Pr, is found to decrease both velocity, temperature and skin friction but elevates heat transfer rate (Nusselt number). The study is relevant to chemical materials processing applications.


Palit S.,Judges Bagan | Palit S.,Salalah College of Technology
International Journal of ChemTech Research | Year: 2012

The vision of environmental engineering is wide, varied and unparalled. The changing world has prompted scientists to target towards green chemistry and green engineering. Green engineering encompasses environmental engineering. The path of success is visionary. Environmental engineering along with dye degradation techniques is ushering in a new era and new vision environmental pollution control. Conventional and traditional textile wastewater and effluent treatment procedures are a challenge to environmental engineers and environmental scientists because of the restrictions on effluent quality by the environmental pollution control authorities. Dyes cannot be destroyed by primary and secondary treatments. Primary treatment encompasses coagulation and flocculation while secondary treatment involves activated sludge process. Both of these treatments do not successfully degrade textile dyes and the dyes are recalcitrant to these treatments. So the need for tertiary treatment process-advanced oxidation process such as ozonation. Bubble column reactor is an efficient and visionary alternative to the environmental pollution problem. The present aim and objective is to present and project effectively the importance of bubble column reactor and ozonation of dyes as the reaction medium in it. The vision of advanced oxidation process will move towards a newer direction if science and technology surges in this new visionary area.


Alami M.,Salalah College of Technology
International Journal of Applied Linguistics and English Literature | Year: 2016

Given that a systematic treatment of Persian Discourse Markers (hereafter DMs) is almost absent in modern Persian linguistics and to bridge this gap, the audio-recorded data comprising 14 face to face casual conversations involving two-party and multi-party interactions among family members, acquaintances and close friends are used to shed light on these ‘frequently used’ but ‘frequently unnoticed’ linguistic elements. To document a list of the most common DMs typically used in Tehrani dialect of Persian language and to have a detailed description of their discoursal functions in talk, Brinton’s (1996) binary classification of DMs functions (textual and interpersonal) was developed to provide an empirically-supported account of the functions and position of Persian DMs in interaction among Tehrani speakers. The present account of DMs which is basically ‘analytical description’ provides the reader with the knowledge about how Persian DMs operate in actual usage. The findings are built upon a 3105-word corpus including 14 audio-recorded conversations among 50 participants. Altogether 34 tokens of Persian DMs with an overall 254 occurrences were identified among which na/na baba (no/no daddy) with the total of 33 (12.84%) occurrences were the most frequently used Persian DM in the data which are followed by dige (no English equivalent), aare/ba’ale (yep/yes), yani (I mean), vali (but), haalaa/ alaan (now), bebin/nega kon (look) and aslan (by no means/ never).To the author, research on the functions and distributional patterns of Persian DMs will broaden our knowledge of their discoursal behavior in language in general and contribute to the already growing cross-linguistic body of work on DMs. © 2016, Australian International Academic Centre PTY LTD. All rights reserved.


Ahmed Khan S.,Salalah College of Technology
Optik | Year: 2011

In their most recent article, Grado-Caffaro et al. have addressed the question of the 'photon velocity'. They have expressed the photon velocity in terms of the wavefunctions of the Klein-Gordon equation (Grado-Caffaro and Grado-Caffaro [4]). In this note, we closely follow their work and explicitly obtain the photon velocity using the free solutions of the Klein-Gordon equation. It is shown that the plane wave solutions give rise to six possible values of the photon velocity. Two of these solutions are the most expected (v=c). The remaining four solutions, the real pair 0.786c and the imaginary pair 1.272ic are difficult to comprehend. © 2010 Elsevier GmbH © 2010 Published by Elsevier GmbH. All rights reserved.


Khan S.A.,Salalah College of Technology
Optik | Year: 2010

Matrix representations of Maxwell's equations have a striking resemblance to the Dirac equation. We exploit this resemblance to build a beam optics formalism from an exact eight-dimensional matrix representation of the Maxwell equations. The Foldy-Wouthuysen iterative diagonalization technique is employed to obtain a Hamiltonian description for a system with varying refractive index. The beam-optical Hamiltonian is shown to have a wavelength-dependent part, resulting in the wavelength-dependent modifications of light beam optics. The present study is the generalization of the traditional and non-traditional prescription of Helmholtz optics. © 2008 Elsevier GmbH. All rights reserved.


Alami M.,Salalah College of Technology
International Journal of Applied Linguistics and English Literature | Year: 2016

Given the fact that English is the language of the latest technological and scientific developments, comprehending English texts has priority for students to gain the knowledge and skills they will need in the future. However, most Omani students are not efficient L2 readers and do not have sufficient competence in reading authentic English texts. There is a variety of factors that might affect Omani students’ ability to read and comprehend English texts effectively. To find out what factors are involved in Omani students’ reading comprehension, in the first place, it is necessary to know what strategies they employ in reading. To this end, the current study attempts to explore Omani students reported use of reading strategies using ‘Metacognitive Awareness of Reading Strategies Inventory’ (MARSI) developed by Mokhtari and Reichard (2002). The self-reported survey completed by 200 students (90 female and 110 male) who enrolled for Advanced Foundation program (level 4) at Salalah College of Technology (SCT). The results show that SCT students’ awareness of metacognitive strategies is at medium level (3.46). Furthermore, the comparison between two gender groups (Males Vs. Females) shows that male students use metacognitive reading strategies moderately (3.28) while female students use them more frequently (3.64). The outcomes of the study contribute to the improvement of SCT students reading ability and can be used by teachers to teach students different strategies to build meaning of the reading material which is among the goals of any educational system. © 2016, Australian International Academic Centre PTY LTD. All rights reserved.


Khan S.A.,Salalah College of Technology
Optik | Year: 2014

An exact treatment of beam optics, starting ab initio from the Maxwell's equations is presented. The starting point of this approach is a matrix representation of the Maxwell's equation in a medium with varying permittivity and permeability. Formal expressions are obtained for the paraxial and leading order aberrating Hamiltonians, without making any assumptions on the form of the varying refractive index. We derive the wavelength-dependent contributions at each order, starting with the lowest-order paraxial Hamiltonian. To illustrate the general theory, we consider the computations of the transfer maps for an axially symmetric graded-index medium. For this system, in the traditional approaches, one gets only six aberrations. In our formalism, we get all the nine aberrations permitted by the axial symmetry. The six aberrations coefficients of the traditional approaches get modified by the wavelength-dependent contributions and the remaining three are pure wavelength-dependent. It is very interesting to note that apart from the wavelength-dependent modifications of the aberrations, this approach also gives rise to the image rotation. The present study is the generalization of the traditional and non-traditional prescription of Helmholtz optics. In the low wavelength limit our formalism reproduces the Lie algebraic formalism of optics. The present study further strengthens the close analogies between the various prescriptions of light optics and charged-particle optics. The new formalism presented here, provides a natural framework to study beam-optics and polarization in a unified manner. © 2013 Elsevier GmbH.

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