King Abdelaziz University

Jeddah, Saudi Arabia

King Abdelaziz University

Jeddah, Saudi Arabia
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Khidr S.,King Abdelaziz University | Khidr S.,Beni Suef University | Abdelkader O.,Minia University
Complex Analysis and Operator Theory | Year: 2014

In this paper, we study the global boundary regularity of the ∂̄- equation on an annulus domain Ω between two strictly q-convex domains with smooth boundaries in ℂn for some bidegree. To this finish, we first show that the ∂̄ -operator has closed range on L2 r,s(Ω) and the ∂̄-Neumann operator exists and is compact on L2 r,s(Ω) for all r ≥ 0, q ≤ s ≤ n - q - 1. We also prove that the ∂̄-Neumann operator and the Bergman projection operator are continuous on the Sobolev space Wk r,s(Ω), k ≥ 0, r ≥ 0, and q ≤ s ≤ n - q - 1. Consequently, the L2-equation on such domain is established. As an application, we obtain a global solution for the ∂̄ equation with Hölder and Lp-estimates on strictly q-concave domain with smooth C2 boundary in ℂn, by using the local solutions and applying the pushing out method of Kerzman (Commun Pure Appl Math 24:301-380, 1971). © 2013 Springer Basel.

El-Mossalamy E.H.,King Abdelaziz University | Mahmoud W.E.,King Abdelaziz University | Al-Owais A.,King Saud University | Arafa H.M.,University of Tabuk
Chemistry and Technology of Fuels and Oils | Year: 2011

The dielectric parameters of polyvinyl alcohol containing 0-0.8 wt. % vanadium pentoxide are studied in the temperature range 20-150 °C at different frequencies: the dielectric constant, dielectric losses, and tangent of the angle of dielectric losses. Cole-Cole plots are used to determine the static dielectric constant and the dielectric constant at infinitely high frequency. The relaxation time is determined at different frequencies as a function of the tangent of the angle of dielectric losses versus the temperature. It is found that the relaxation properties follow the Arrhenius equation, the activation energy decreases with the vanadium pentoxide content in polyvinyl alcohol. An investigation of the dielectric relaxation as a function of temperature at constant frequency revealed two types of relaxation processes: dipole-segmented motion (α-relaxation) and side-chain dipole group motion (β-relaxation). The ac conductivity in the system polyvinyl alcohol - vanadium pentoxide is explained on the basis of the correlated barrier hopping model. © 2011 Springer Science+Business Media, Inc.

Ng J.,University of Alberta | Dubljevic S.,University of Alberta | Aksikas I.,University of Alberta | Aksikas I.,King Abdelaziz University
2011 19th Mediterranean Conference on Control and Automation, MED 2011 | Year: 2011

This paper presents a model predictive control (MPC) formulation for the Czochralski (CZ) crystal growth which is given by the discrete finite-dimensional system representation of a class of parabolic partial differential equations (PDEs) with time-varying features. The motivation behind this work is to address the problem of stabilizing, infinite horizon, linear quadratic regulator synthesis for PDEs with time-dependent parameters which affect the dynamics of the underlying system and appear in the state-space representation. The modal decomposition of the PDE facilitates its approximation by a finite-dimensional linear state-space system. A receding horizon regulator is proposed which incorporates the time-dependence of the PDE parameters and numerical simulations are carried out which demonstrate the optimal stabilization of the process under state and input constraints. © 2011 IEEE.

Habib H.S.,King Abdelaziz University
Journal of Pediatric Neurology | Year: 2013

Moyamoya disease is a progressive vascular disease associated with steno-occlusion of the terminal portions of the internal carotid arteries and with several congenital and acquired conditions, including ischemic stroke in young children. This case report describes the discovery of an unusual association between moyamoya disease and type 1 diabetes mellitus in a 9-year-old child presenting with stroke-associated diabetic ketoacidosis. Discovery of this case highlights the importance of considering stroke as well as cerebral edema, the more likely etiology, in the differential diagnosis of neurological deterioration in children with diabetic ketoacidosis, as well as considering moyamoya syndrome in the diagnosis of diabetic children presenting with stroke. © 2013 - IOS Press and the authors. All rights reserved.

Ng J.,University of Alberta | Dubljevic S.,University of Alberta | Aksikas I.,King Abdelaziz University
Proceedings of the American Control Conference | Year: 2012

There are many industrial and biological reaction-diffusion systems which exhibit time-varying features where certain parameters of the system change during the process. The underlying transport-phenomena are often modelled using parabolic partial differential equations (PDEs) with time-varying coefficients which describe the dynamics of the process. Often it is of interest to control this dynamical behaviour such as the regulation of temperature or concentration, and one approach is the use of infinite-dimensional systems theory to represent the PDE models, with time-varying process parameters, as abstract nonautonomous evolution equations on appropriately defined function spaces. In contrast to timeinvariant control problems, the theory for controllability and observability for time-varying systems is less well established. In this work, we consider some pertinent aspects regarding the controllability and observability of nonautonomous infinite-dimensional systems. An example is considered for which the conditions for exact, null, and approximate controllability and observability are verified, and some observations regarding the influence of time-varying input and measurement operators are provided. © 2012 AACC American Automatic Control Council).

Naji H.S.,King Abdelaziz University | Khalil Khalil M.,King Abdelaziz University
Arabian Journal of Geosciences | Year: 2012

Oil was first discovered in the Masila area of Yemen in the late 1990s, with about 90% of the reserves found in the Lower Qishn Clastic Member of the Qishn Formation. The porosity determinations of the Lower Qishn Clastic are relatively high and the permeability ranges from 103 to 374 md. This paper tries to evaluate the hydrocarbons in the porous zones encountered in the Lower Cretaceous formations, which were penetrated by the eight wells in the study area. The water saturation shows low values, while the hydrocarbon saturation is in a reverse relation, i.e., the hydrocarbon increases where the water saturation decreases. Different cross-plots such as Rho-PHIN, Rho-DTN, and M-N were used in lithological identification for the two studied formations (Saar and Qishn) in the studied wells. Formation evaluation and presentation forms of the obtained petrophysical parameters have frequently proven that the formations have high hydrocarbon saturation in this area and contain many pay zones. On of the main targets of this paper is to build a detailed 3D geological modeling of the Lower Cretaceous Sequence conducted through an integrated study. © Saudi Society for Geosciences 2010.

Alakilli S.Y.M.,King Abdelaziz University
Saudi Journal of Biological Sciences | Year: 2010

In this study, Drosophila melanogaster males were treated with parsley plant extract and the anticancer drug vincristine (VCR) singly and in combined treatments (pre, co and post-treatments) to detect the mutagenic effects by using sex-linked recessive lethal test (SLRL) and estimation of cholinesterase enzyme (ChE) activities in order to compare the sensitivity of the two test systems. A wild type strain Oregon-R (Or-R) male flies of D. melanogaster were reared on a medium containing one concentration of each of VCR and parsley (4 ml/100 ml medium) in each single and combined treatment. Also the activity of ChE was estimated in some insects of the two generations: F1 females, F2 bar eye females (heterozygous) and F2 wild types males. The results indicate that both of parsley and vincristine did not cause significant increases of SLRL test in either the single or combined treatments. In contrast, estimation of ChE activities showed significant increase in all the broods within single and combination treatments, except female of the second generation of spermatid brood which treated with parsley and VCR at the same time. It is concluded that enzyme estimation is more sensitive than SLRL test for detection the mutagenic effect for parsley's extract and vincristine. © 2009.

Ouassila L.,University Mentour | Hassan M.A.,University Mentour | Ahmed Z.,University Mentour | Yacine K.,King Abdelaziz University | Thierry C.,Laboratoire des science Du Genie Chimique
Energy Procedia | Year: 2012

In the present work a new configuration of absorption refrigeration machine based on phase separation has been studied. The main objective is to investigate the performance of this machine, using a number of binary systems (refrigerant absorbent) showing a partial miscibility and having a low critical solution temperature. A computer code has been developed for the calculation of the coefficient of performance (COP) of the machine as well as to study the influence of the operating conditions on this parameter, testing a binary mixture made of methyl diethyl amine (MDEA) as refrigerant and water as absorbent. The obtained results confirm the feasibility of this new cycle which can be regarded as a good alternative to classical cycle with no phase separation. The use of the computer code can be extended to test different working fluids for this machine, for an optimisation of the COP. © 2012 Published by Elsevier Ltd.

Moghadam A.A.,University of Alberta | Aksikas I.,University of Alberta | Aksikas I.,King Abdelaziz University | Dubljevic S.,University of Alberta | Forbes J.F.,University of Alberta
Proceedings of the IEEE Conference on Decision and Control | Year: 2011

This contribution addresses the development of a Linear Quadratic regulator (LQ) for controlling concentration profiles along a catalytic distillation column which is modelled by a set of coupled hyperbolic Partial Differential and Algebraic Equations (PDAEs). The methodology is based on an infinite-dimensional representation of the system and solving the related Operator Riccati Equation (ORE). The performance of the designed control policy is assessed through a numerical simulation. © 2011 IEEE.

PubMed | King Abdelaziz University
Type: Journal Article | Journal: Journal of pediatric neurosciences | Year: 2011

Adhesion molecules play a role in leukocyte recruitment during central nervous system (CNS) inflammation.This study was designed to compare serum, cerebrospinal fluid (CSF) concentrations of adhesion molecules in children with meningitis and sepsis, and to evaluate their sources.This study was carried out at Pediatric Department, King Abdulaziz University Hospital from January 2007 to June 2008.Serum and CSF samples were collected on admission from meningitis (n = 40), sepsis (n = 20) patients, and sera from controls (n = 20).Endothelial (E), leukocyte (L), platelet (P) selectins intercellular cell adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecules-1 (VCAM-1) were measured using ELISA.ANOVA and Spearmans correlations were used. Adhesion molecules with albumin concentration were estimated in CSF/serum to calculate concentration quotients.In meningitis, serum sE-, sL-, sP-selectins sICAM-1, sVCAM-1 levels were higher than controls. Compared to sepsis, serum sE-selectin, sL-selectin, sVCAM-1, CSF-sL-selectin, CSF-sVCAM-1, VCAM-1 ratio and index were higher, while serum sP-selectin was lower than meningitis. sE-selectin ratio, CSF sICAM-1 were higher in meningitis with positive than negative culture. The sE-selectin index was higher in meningitis with neurological complication than those without it. In meningitis, correlation was found between CSF protein and CSF white blood cell counts (WBCs), CSF sICAM-1, CSF sVCAM-1 and between CSF sE-selectin and CSF sICAM-1.This study supports the role of adhesion molecules especially sL-selectin, sVCAM-1 in meningitis and suggests further research to determine their use as biomarkers for meningitis and use of their antagonists as therapeutic for CNS inflammation. The presence of discrepancy of CSF/serum ratios for molecules of same molecular weight suggest intrathecal shedding in addition to diffusion through the blood-CSF barrier.

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