Salalah, Oman
Salalah, Oman

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Jabeur N.,Arab Open University | Zeadally S.,University of the District of Columbia | Sayed B.,Dhofar University
Communications of the ACM | Year: 2013

The latest advances in mobile computing, hardware, and software empower end users worldwide through a range of mobile devices with improved and novel capabilities. The result is intense competition among providers of online social services for mobile users regardless of location and profile, along with numerous mobile social networking (MSN) applications in which billions of people use their mobile devices to tap a spectrum of instant, relevant, high-quality services. MSN applications are social structures consisting of individuals or organizations connected through specific types of interdependency similar to online social networking sites (OSNS). They are based on a variety of architectures depending on whether they are extensions of existing OSNS, designed for mobile devices, focused on mobile users, or data- or service-oriented.

Eltayeb T.K.,Dhofar University | Zailani S.,Universiti Sains Malaysia | Ramayah T.,Universiti Sains Malaysia
Resources, Conservation and Recycling | Year: 2011

The relationship between green supply chain initiatives and performance outcomes has been subject to numerous studies but the results are not conclusive. This study tries to assess the actual environmental, economic and intangible outcomes resulting from the adoption of green supply chain initiatives. This study used a structured questionnaire derived from the literature and employing a mail survey to collect responses form a group of 569 ISO 14001 certified firms in Malaysia. The results of testing the hypotheses that predicted that green supply chain initiatives have positive effect on the outcomes showed that eco-design have significant positive effect on the four types of outcomes (environmental outcomes, economic outcomes, cost reductions, and intangible outcomes). Reverse logistics was found to have significant positive effect on cost reductions only. However, green purchasing was not found to have significant effect on any of the four types of outcome. Through designing environmentally friendly products and taking back products and packaging, business organizations can generate benefits to the environment, in the form of reduced waste and better resource utilization, in addition to economic benefits and cost reductions to the organizations. © 2010 Elsevier B.V. All rights reserved.

Abu Abdo A.M.,Dhofar University
Road Materials and Pavement Design | Year: 2012

Asphalt pavement designers have been using the dynamic modulus (|E*|) as a fundamental parameter to reflect the hot-mix asphalt (HMA) performance, and since |E*| is considered as an essential input in the new AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG), many models were developed for evaluating and/or predicting this property for HMA. This article focuses on the verification of a newly developed model to predict |E*| by utilising robust sensitivity analyses through tornado plots and extreme tail analyses, which are used to identify the relative importance of the input variables on the predicted |E*|. Results showed that the binder dynamic shear modulus (|G*|) has the most significant effect, followed by the air void content, on the predicted |E*|, and both properties contributed largely to the extreme predicted values. © 2012 Taylor & Francis.

Horchani R.,Dhofar University
Frontiers of Physics | Year: 2016

Optical pumping techniques using laser fields combined with photo-association of ultracold atoms leads to control of the vibrational and/or rotational population of molecules. In this study, we review the basic concepts and main steps that should be followed, including the excitation schemes and detection techniques used to achieve ro-vibrational cooling of Cs2 molecules. We also discuss the extension of this technique to other molecules. In addition, we present a theoretical model used to support the experiment. These simulations can be widely used for the preparation of various experiments because they allow the optimization of several important experimental parameters. © 2016, Higher Education Press and Springer-Verlag Berlin Heidelberg.

Wazwaz A.,Dhofar University | Al-Salaymeh A.,University of Jordan
Energy Conversion and Management | Year: 2013

The alternate and reverse periodic plating techniques were used to prepare the selective absorber samples. The glazed type-flat plate collector was used for photothermal testing. The calculated absorptivity of the selective absorbers (before degradation) falls in the range 92.0-97.0% and after degradation falls in the range 88.3-92.2%; while emissivity (before degradation) falls in the range 11.0-22.5% and after degradation falls in the range 11.6-23.4%. The maximum calculated net collective flux (before degradation) is in the range 590-699 W/m-2 and after degradation is in the range 566.4-664.1 W/m-2. The conversion efficiency (before degradation) is in the range 0.73-0.78 and after degradation falls in the range 0.70-0.74. Degradation testing carried out in air at different temperatures: 100 °C, 200 °C, 250 °C, and 300 °C. The degradation process leads to a decrease in the solar absorptivity and increase in the thermal emissivity of the films especially at 300 °C. Different parameters are discussed concerning the photothermal and the degradation testing. © 2012 Elsevier Ltd. All rights reserved.

Nawayseh N.,Dhofar University | Griffin M.J.,University of Southampton
Journal of Sound and Vibration | Year: 2010

Previous studies have quantified the power absorbed in the seated human body during exposure to vibration but have not investigated the effects of body posture or the power absorbed at the back and the feet. This study investigated the effects of support for the feet and back and the magnitude of vibration on the power absorbed during whole-body vertical vibration. Twelve subjects were exposed to four magnitudes (0.125, 0.25, 0.625, and 1.25 m s-2 rms) of random vertical vibration (0.25-20 Hz) while sitting on a rigid seat in four postures (feet hanging, maximum thigh contact, average thigh contact, and minimum thigh contact) both with and without a rigid vertical backrest. Force and acceleration were measured at the seat, the feet, and the backrest to calculate the power absorbed at these three locations. At all three interfaces (seat, feet, and back) the absorbed power increased in proportion to the square of the magnitude of vibration, with most power absorbed from vibration at the seat. Supporting the back with the backrest decreased the power absorbed at the seat at low frequencies but increased the power absorbed at high frequencies. Supporting the feet with the footrest reduced the total absorbed power at the seat, with greater reductions with higher footrests. It is concluded that contact between the thighs and the seat increases the power absorbed at the seat whereas a backrest can either increase or decrease the power absorbed at the seat. © 2010 Elsevier Ltd. All rights reserved.

Hussain I.,National University of Computer and Emerging Sciences | Gondal M.A.,Dhofar University
Nonlinear Dynamics | Year: 2014

This manuscript is about a modified image encryption algorithm based on coupled map lattices and substitution box transformation. The places of the pixels of image are mix up by using chaotic tent map and after that employing delayed coupled map lattices and S-box transformation to puzzle the association between the original image and the encrypted image. The simulation results validate that the propose technique possesses better strength for realistic image encryption. © 2014 Springer Science+Business Media Dordrecht.

Horchani R.,Dhofar University
European Physical Journal Plus | Year: 2016

A strong asymmetric light transport in a linear chain of spherical and equidistantly spaced silver metal nano-particles (MNPs) located near a substrate is reported. The contrast ratio of the proposed structure is above 0.95. We have studied the propagation of light in the array with respect to the metal and the size of the last nano-particle of the chain and the nature of the substrate. It is shown also that the presence of a copper or gold substrate enhance the guiding properties of the array. This structure opens the possibility to design various optical devices such as broadband antennae and optical diodes. © 2016, Società Italiana di Fisica and Springer-Verlag Berlin Heidelberg.

Al-Waked R.,Dhofar University
International Journal of Thermal Sciences | Year: 2010

Effects of crosswinds on the thermal performance of natural draft wet cooling towers (NDWCTs) have been investigated. A three-dimensional CFD model has been used to determine the effect of crosswinds on NDWCTs performance surrounded by power plant building structures. The three-dimensional CFD model has utilized the standard k-ε turbulence model as the turbulence closure. Two cases have been investigated: a stand-alone NDWCT and two NDWCTs within a proposed power plant structures (PPS). It has been found that regardless of the crosswinds direction, an increase of 1.3 k or more could be predicted at crosswinds speeds greater than 4 m/s. Furthermore, the performance of NDWCTs under crosswinds has been found to be dependent on the three major factors: the structure of the approaching crosswinds and whether it is disturbed or undisturbed, the location of the NDWCT in the wake of the other NDWCT, and the location of the NDWCT in front of/in the wake of the PPS. When comparing results from the stand-alone and from the NDWCTs within PPS simulations, differences in ΔTwo were found to be less than 1 K for the whole span of crosswinds speeds and could be decreased to 0.7 K for speeds less than 8 m/s. Finally, results obtained from the simulation of a stand-alone NDWCT could be used instead of those from NDWCTs within PPS at a certain crosswinds direction for qualitative comparisons. © 2009 Elsevier Masson SAS. All rights reserved.

Khan S.A.,Dhofar University
Journal of Modern Optics | Year: 2016

The way to generalize scalar to wave optics, thus including polarization in the treatment consistent with the Maxwell equations was shown by Mukunda, Simon and Sudarshan for paraxial systems, based on a group theoretical analysis. Here, the Mukunda–Simon–Sudarshan (MSS) theory for the passage from scalar to vector optics is derived by casting the basic formalism in a framework very similar to the Dirac electron theory. The resulting formalism is suitable for extending the MSS-theory beyond the paraxial approximation. © 2016 Informa UK Limited, trading as Taylor & Francis Group

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