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Khan A.D.,Sarhad University of Science and Information Technology | Khan S.D.,University of Milan Bicocca | Khan R.U.,Sarhad University of Science and Information Technology | Ahmad N.,Northern Borders University
Plasmonics | Year: 2014

The presence of plasmonic Fano-like resonances in the optical response of isolated and dimer metal-dielectric-metal nanostructures are investigated theoretically. The nanostructures are engineered in such a way to support multiple Fano-like resonances that are induced by the interference of bright and dark plasmon modes. It is found that the dimer resonators exhibit different types of Fano resonances for both the transverse and longitudinal polarizations unlike conventional nanodimers. Several configurations of the dimer Fano resonator are analyzed with special emphasis on the Fano spectral line shape. Breaking the symmetry of the dimer nanostructure in various directions control the asymmetric line shape and provides different kinds of unique Fano resonances. In certain cases, the Fano resonators exhibit multiple Fano resonances that are particularly significant for plasmon line shaping and can serve as platforms for multi-wavelength sensing applications. © Springer Science+Business Media New York 2013.

Aljahdali M.,Northern Borders University | Aljahdali M.,King Abdulaziz University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

The ternary complexes of Cu(II), Zn(II), Ni(II) and Cd(II) with 2-aminomethylbenzimidazole (AMBI) and glycine as a representative example of amino acids have been isolated and characterized by elemental analyses, IR, ESR, UV-vis, magnetic moment, molar conductance and 1H NMR spectra. AMBI behaves as neutral bidentate ligands with coordination through imidazole and amino group nitrogens while the glycine amino acid behaves as a monodenate anion with coordination involving the amino group and carboxylate oxygen after deprotonation. The magnetic and spectral data indicates a square planar geometry for both Cu2+ and Ni2+ complexes and a tetrahedral geometry for both Zn2+ and Cd2+ complexes. The isolated chelates have been screened for their antifungal and antibacterial activities using the disc diffusion method. A cytotoxicity of the compounds against colon (HCT116) and larynx (HEP2) cancer cells have been studied. The stability constants of ternary M-AMBI-Gly complexes were determined potentiometrically in aqueous solution at I = 0.1 mol dm-3 NaCl. © 2013 Elsevier B.V. All rights reserved.

Dehouche N.,Northern Borders University
2015 International Conference on Cloud Computing, ICCC 2015 | Year: 2015

Cloud computing is an emerging form of distributed computing that enables a reliable on-demand access to critical Information Technology (IT) services. This flexible access generally allows organizations to improve both their productivity and profitability compared to previous ownership-based computing paradigms. On the other side of the coin, the IT sector as a whole and data centers used in cloud computing infrastructures in particular, are responsible for a significant contribution to global carbon dioxide emissions. Energy consumption and carbon imprints of Cloud infrastructures have thus become a key environmental concern, and several approaches have been proposed with the aim of increasing their energy-efficiency, both within individual data centers and at the level of the infrastructure as a whole. Among these approaches, low-carbon routing algorithms offer operational solutions, which consist in dynamically routing connection requests in order to maximize the use of renewable energy or, equivalently, minimize the use of non-renewable energy. The main claim of this paper is that the existing body of methods suffers from some practical limitations due to the fact that they consider a single objective, at the possible expense of other important aspects such as Quality of Service and cost. Therefore, we propose a bi-criteria routing model, in which both carbon reduction and quality of service, in the form of data transmission delay, are considered as objectives to optimize. Under this model, which to the the best of our knowledge is the fist bi-criteria formulation of the dynamic routing problem in Cloud computing environments, We describe an algorithm to compute efficient supported and non-supported solutions in order to dynamically route connection requests. The application of our algorithm is illustrated through a case study simulated under the same conditions as a previously published work considering a single criterion approach and comparison results are drawn. © 2015 IEEE.

Abdelaziz T.H.S.,Helwan University | Abdelaziz T.H.S.,Northern Borders University
IET Control Theory and Applications | Year: 2013

This paper considers the robust pole assignment problem using combined velocity and acceleration feedbacks for matrix second-order linear systems. The necessary and sufficient conditions which ensure solvability are derived. Based on recently developed parametric solution to the eigenstructure assignment problem by velocity-plus-acceleration feedback, a new technique is described to perform robust pole placement for second-order systems. The available degrees-of-freedom offered by the velocity-plus-acceleration feedback in selecting the associated eigenvectors are utilised to improve robustness of the closed-loop system. The main advantage of the described approach is that the problem is tackled in the second-order form without transformation into the first-order form. Finally, several examples are introduced to demonstrate the effectiveness of the proposed approach. © The Institution of Engineering and Technology 2013.

Aljahdali M.,King Abdulaziz University | El-Sherif A.A.,Cairo University | El-Sherif A.A.,Northern Borders University
Inorganica Chimica Acta | Year: 2013

A combined experimental and computational study of novel mixed ligand Cu(II), Ni(II) and Co(II) complexes of 2-(1-(2-phenyl-hydrazono)-propan-2- ylidene)hydrazine-carbothioamide (TPHP) and 1,10-phenanthroline (1,10-Phen) have been synthesized. The complexes have been characterized by elemental analyses, IR, solid reflectance, magnetic moment, 1HNMR and molar conductance. Spectral data showed that the 1,10-phenanthroline acts as neutral bidentate ligand coordinating to the metal ion through two nitrogen donor atoms and thiosemicarbazone acts as monobasic tridentate coordinating through two imine-N and thiolate sulphur groups. The geometry of the studied M(II) complexes has been fully optimized using parameterized PM3 semiempirical method. It was observed that the M-S bond length is longer than that of M-Cl in the isolated complexes and the M-N bond length is shorter than that of M-Cl. Also, valuable information is obtained from calculations of molecular parameters for all complexes including net dipole moment of the metal complexes, values of binding energy, which proved that the complexes are more stable than the free ligand. The metal chelates have been screened for their antimicrobial activities using the disc diffusion method against different selected types of bacteria (G +: Bacillus subtillis RCMB 010067, Staphylococcus aureus RCMB 010028); G-: Pseudomonas aeuroginosa RCMB 010043, Escherichia coli RCMB 010052)) and fungi (Aspergillus flavus RCMB 02568, Pencicillium italicum RCMB 03924, Candida albicans RCMB 05031, Geotricum candidum RCMB 05097). Finally, structure-activity relationship studies were investigated with the aim to correlate physico-chemical properties that may be related to the antimicrobial action of the studied compounds. Protonation constant of (TPHP) ligand and stability constants of its M(II) complexes were determined by potentiometric titration method in 70%:30% DMSO-water mixture at 0.1 mol dm -3 NaCl. © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

El-Mallawany R.,Northern Borders University
Journal of Non-Crystalline Solids | Year: 2013

Binary tellurite glasses in the form (100 - x)TeO2-xA nOm and AnOm = Nb2O 5 and WO3 oxides have been prepared by the melt quenching technique and x = 4, 10 mol% for Nb2O5 and 20 mol% WO 3. Density and molar volume have been measured and calculated. Differential scanning calorimetric curves of these glasses have been investigated to measure thermal properties of these glasses. The thermal properties were the glass transition temperature Tg (C), the onset of crystallization temperature Tx (C) and the glass stability S = (Tx - Tg) (C). The glass transition temperature has been analyzed according to the average crosslink density that is present in the glass. © 2013 Elsevier B.V.

Kotb A.,Fayoum University | Kotb A.,Northern Borders University
Optoelectronics Letters | Year: 2013

The NAND operation at 250 Gbit/s based on quantum dot-semiconductor optical amplifiers (QD-SOAs) is modeled. By solving the rate equations of SOAs in the form of a Mach-Zehnder interferometer (MZI), the performance of NAND gate is numerically investigated. The model takes the effects of amplified spontaneous emission (ASE) and the input pulse energy on the system's quality factor into account. Results show that NAND gate in QD-SOA-MZI based structure is feasible at 250 Gbit/s with a proper quality factor. The decrease in quality factor is predicted for high spontaneous emission factor (NSP). For an ideal amplifier (NSP = 2), the Q-factor is 17. 8 for 30 dB gain. © 2013 Tianjin University of Technology and Springer-Verlag Berlin Heidelberg.

Kotb A.,Fayoum University | Kotb A.,Northern Borders University
Optical and Quantum Electronics | Year: 2013

The performance of all-optical logic NOR gate based on quantum-dot- semiconductor optical amplifier (QD-SOA) is simulated. By solving the rate equations of QD-SOAs when incorporated in the arms of a Mach-Zehnder interferometer the performance of NOR gate is numerically investigated. The model takes into account the impact of the amplified spontaneous emission, the input pulse energy and the injection current density on the system's quality factor. Results show that NOR gate using QD-SOA is capable of operating at speeds of 250 Gbit/s with proper quality-factor. © 2013 Springer Science+Business Media New York.

Kotb A.,Fayoum University | Kotb A.,Northern Borders University
Optical and Quantum Electronics | Year: 2013

The performance of all-optical logic gate NOR has been simulated. NOR operation is realized by using Mach-Zehnder interferometer utilizing semiconductor optical amplifier (SOA) with quantum-dot (QD) active region. Nonlinear dynamics including carrier heating and spectral hole-burning in the QD-SOA are taken into account together with the rate equations in order to realize the all-optical logic NOR operation. The study is carried out when the effect of amplified spontaneous emission is taken into account in the simulation analysis. Results show that the NOR operation is capable of operating at a data speed of 1 Tb/s with high output quality factor (Q-factor). The dependence of the output Q -factor on QD-SOA parameters is also investigated and discussed. © 2013 Springer Science+Business Media New York.

Northern Borders University | Date: 2015-12-15

Improved buffer overflow protection for a computer function call stack is provided by placing a predetermined ShadowKEY value on a functions call stack frame and copying the ShadowKEY, a caller EBP, and a return pointer are pushed onto a duplicate stack. The prologue of the function may be modified for this purpose. The function epilogue is modified to compare the current values of the ShadowKEY, caller EBP, and the return pointer on the function stack to the copies stored on the duplicate stack. If they are not identical, an overflow is detected. The preserved copies of these values may be copied back to the function stack frame thereby enabling execution of the process to continue. A function prologue and epilogue may be modified during compilation of the program.

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