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‘Ayn al ‘Arab, Syria

Adeka M.,University of Bradford | Shepherd S.,University of Bradford | Abd-Alhameed R.,University of Bradford | Ahmed N.A.S.,Azzaytuna University
2015 Internet Technologies and Applications, ITA 2015 - Proceedings of the 6th International Conference | Year: 2015

The Versatile and Ubiquitous Secret Sharing System, a cloud data repository secure access and a web based authentication scheme. It is designed to implement the sharing, distribution and reconstruction of sensitive secret data that could compromise the functioning of an organisation, if leaked to unauthorised persons. This is carried out in a secure web environment, globally. It is a threshold secret sharing scheme, designed to extend the human trust security perimeter. The system could be adapted to serve as a cloud data repository and secure data communication scheme. A secret sharing scheme is a method by which a dealer distributes shares of a secret data to trustees, such that only authorised subsets of the trustees can reconstruct the secret. This paper gives a brief summary of the layout and functions of a 15-page secure server-based website prototype; the main focus of a PhD research effort titled 'Cryptography and Computer Communications Security: Extending the Human Security Perimeter through a Web of Trust'. The prototype, which has been successfully tested, has globalised the distribution and reconstruction processes. © 2015 IEEE. Source

Baqar M.,Case Western Reserve University | Baqar M.,Azzaytuna University | Agag T.,Case Western Reserve University | Agag T.,Tanta University | And 4 more authors.
Macromolecules | Year: 2012

The polymerization mechanism of methylol-functional benzoxazine monomers is reported using a series of monofunctional benzoxazine monomers synthesized via a condensation reaction of ortho-, meta-, or para-methylol-phenol, aniline, and paraformaldehyde following the traditional route of benzoxazine synthesis. A phenol/aniline-type monofunctional benzoxazine monomer has been synthesized as a control. The structures of the synthesized monomers have been confirmed by 1H NMR and FT-IR. The polymerization behavior of methylol monomers is studied by DSC and shows an exothermic peak associated with condensation reaction of methylol groups and ring-opening polymerization of benzoxazine at a lower temperature range than the control monomer. The presence of methylol group accelerates the ring-opening polymerization to give the ascending order of para-, meta-, and ortho-positions in comparison to the unfunctionalized monomer. Furthermore, rheological measurements show that the position of methylol group relative to benzoxazine structure plays a significant role in accelerating the polymerization. © 2012 American Chemical Society. Source

Almradi A.M.,Azzaytuna University | Dianat S.A.,Rochester Institute of Technology
International Journal of Business Data Communications and Networking | Year: 2012

This paper discusses the problem of Non Data Aided (NDA) Signal to Noise Ratio (SNR) estimation of Binary Phase Shift keying (BPSK) modulated signals using the Expectation Maximization (EM) Algorithm. In addition, the Cramer-Rao Lower Bounds (CRLB) for the estimation of Data Aided (DA) and Non Data Aided (NDA) Signal to Noise Ratio (SNR) estimation is derived. Multiple Input Single Output (MISO) channels with Space Time Block Codes (STBC) is used. The EM algorithm is a method that finds the Maximum Likelihood (ML) solution iteratively when there are unobserved (hidden or missing) data. Extension of the proposed approach to other types of linearly modulated signals in estimating SNR is straight forward. The performance of the estimator is assessed using the NDA CRLBs. Alamouti coding technique is used in this paper with two transmit antennas and one receive antenna. The authors' assumption is that the received signal is corrupted by additive white Gaussian noise (AWGN) with unknown variance, and scaled by fixed unknown complex channel gain. Monte Carlo simulations are used to show that the proposed estimator offers a substantial improvement over the conventional Single Input Single Output (SISO) NDA SNR estimator due to the use of the statistical dependences in space and time. Moreover, the proposed NDA SNR estimator works close to the NDA SNR estimator over Single Input Multiple Output (SIMO) channels. Copyright © 2012, IGI Global. Source

Elfallagh F.A.,Azzaytuna University
Advanced Structured Materials | Year: 2014

The stresses around the Vickers indents in alumina [surface orientation ð11 _ 0 2Þ] were investigated by Cr3+ fluorescence spectroscopy, measuring the shifts in the Cr3+ R1 and R2 luminescence lines. Changes in R1 peak position can be related directly to changes in residual stress of the alumina in the sampled volume, and changes in R1 peak width arise from local stress variations due to microstructural defects such as cracks and dislocations. The intensity of the R1 and R2 fluorescence peaks was observed to decrease with increasing proximity to the indent centre due to increased scattering from residual surface and microstructural damage such as dislocations, cracks and surface debris. © Springer International Publishing Switzerland 2014. Source

Elmehdi A.,Azzaytuna University | Momen A.,University of Idaho | Johnson B.K.,University of Idaho
2014 North American Power Symposium, NAPS 2014 | Year: 2014

Line commutated current source converter-based (LCC) HVDC systems are being considered for the transfer of power from remote wind resources to existing ac transmission systems. The rectifier terminals of these systems are connected to weak ac systems. A modified CIGRE HVDC benchmark model implemented in the PSCAD/EMTDC program is used to study the impact of varying amounts of dynamic reactive compensation on performance during rectifier operation. Determination of the amount of dynamic reactive compensation needed at the rectifier terminal is based on the following dynamic parameters: the magnitude of the first peak of the temporary overvoltages (TOVs) of the rectifier ac voltage following disturbance and time for the dc system to reach 80% of pre-disturbance dc power transfer after the clearing an ac fault. An effective short circuit ratio (ESCR) for best operation will be calculated based on the selected value of the dynamic reactive power compensation rating. © 2014 IEEE. Source

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