F2+ defect based model for tunable laser activity and interaction of atomic halogens (F, Cl and Br) at the low coordinated surfaces of LiH: ab initio calculations

A. S. Shalabi 한국물리학회 2002 Current Applied Physics Vol.2 No.3

The twofold potential ofFþ2 sorption properties for atomic halogens is examined using ab initio calculations.Based on Stokes shifts of the examined clusters, theFþ2 laser activity was very weak, but increases signicantly as the coordination number decreases from 5 (at) to 4 (edge) to 3 (H.corner).The corner site is the least probable for relaxed excited state orientational destruction ofFþ2 .The exciton (energy) transfersurfaces of LiH.TheFþ2 color center change the nature of halogensurface interaction from physical adsorption to chemical ad-sorption.The halogensurface interactions were monotonically increasing functions of the electronegativity of the halogen and theamount of charge transferred between the halogen and the surface.The ‘‘covalent spin pairing’’ mechanism play the dominant rolein the course of adsorbatesubstrate interactions.. 2002 Elsevier Science B.V. All rights reserved.

FA(Ga+, In+, Tl+) tunable laser activity and interaction of halogen atoms (F, Cl, Br, I, At) at the (001) surface of KCl crystal:ab initio calculations

A.S.Shalabi,T.F.El-Essawy,M.M.Assem,S.Abdel-Aal,A.M.El-Mahdy 한국물리학회 2002 Current Applied Physics Vol.2 No.2

An attempt has been made to examineFA(Gaþ ;Inþ ;Tlþ ) tunable laser activity and adsorptivity of halogen atoms (F;Cl;Br;I;At)at the (001) surface of KCl crystal using an embedded cluster model, CIS and density functional theory calculations with eectivecore potentials. The ion clusters were embedded in a simulated Coulomb eld that closely approximates the Madelung eld at thehost surface. The nearest neighbor ions to the defect site were then allowed to relax to equilibrium. Based on the calculated strengthFA(Tlþ ) center was found to be the most laser active inagreement with the experimental observation that the optical emissions ofFA(Inþ ) and FA(Gaþ ) centers were strongly quenched.The disappearance of the anisotropy and np splitting observed in the absorption ofFA(Gaþ ;Inþ ;Tlþ ) centers were monotonicallyincreasing functions of the size of the impurity cation. TheFA(Gaþ ;Inþ ;Tlþ ) defect formation energies followed the orderFAðGaþ Þ> FAðInþ Þ> FAðTlþ Þ. The GlasnerTompkins empirical relationship between the principal optical absorption ofFcentersin solids and the fundamental absorption of the host crystal was generalized to include the positive ion species. As far as the ad-sorptivity of the halogen atoms is concerned, theF and FA(Inþ ;Tlþ physical adsorption to chemical adsorption. The adsorption energies were monotonically increasing functions of the electroneg-ativity of the halogen and the amount of charge transferred from the defect-free surface. The calculated adsorption energies wereexplainable in terms of the electron anity, the eective nuclear charge and the electrostatic potentials at the surface. The spinpairing mechanism played the dominant role in the course of adsorbatesubstrate interactions and the KCl defect-free surface can bemade semiconducting byF or FA(Inþ ;Tlþ ) surface imperfections.. 2001 Elsevier Science B.V. All rights reserved.

The role of type II FB (I):Tl+ defect in laser light generation and color image formation at the low coordination surface sites of AgBr: ab initio calculations

A.S. Shalabi,A.S. Algaber,N.K. Madi,Kh.M. Eid,Z.M. Fathy 한국물리학회 2006 Current Applied Physics Vol.6 No.1

The role of type IIFB (I):Tl+ color center at low coordination surface sites of AgBr thin lms in providing tunable laser activitystructure calculations. Clusters of variable sizes were embedded in simulated Coulomb elds that closely approximate the Madelungelds of the host surfaces, and ions that are the nearest neighbors to theFB defect site were allowed to relax to equilibrium in eachcase. The calculated Stokes shifted optical transition bands suggest that laser activity is relatively weak and fades quickly as thecoordination number of the surface ions decreases from 5 (at) to 4 (edge) to 3 (corner). An attempt has been made to explain thesesurfaces were deep below the lower edges of the conduction bands of the ground-state defect-free surfaces indicating that type IIFB(I):Tl+ is suitable laser defect. The probability of orientational destruction of the two centers, attributed to the assumed saddlepoint ion congurations along theh110i axis, was found to decrease as the coordination number of the surface ions decreases. Thepossibility of exciton (energy) transfer between sites of dierent coordination numbers was claried. The GlasnerTompkins empir-ical relation was generalized to include type IIFB (I):Tl+ doped surfaces. As far as photographic sensitization is concerned, a super-sensitizer increases the sensitizing capabilities of the two examined dye molecules by increasing the relative yield of quantumeciencyU.FA sensitizes the low coordination surface sites of the defect free AgBr by lowering the bottoms of the conductionbands. The dierence in the sensitizing capabilities between the two examined dyes was estimated by calculating the quasi Fermilevels.

FA1:La2+ and FA2:Sc2+ color center lasers and color image sensitization at the low coordination (0 0 1)surface of AgBr by ab initio calculations

A.S.Shalabi,I.A.Z.Al-Ansari,K.Kh.Al-Naimi,M.M.Shalaby,W.S.Abdel Halim 한국물리학회 2004 Current Applied Physics Vol.4 No.5

Using Remote Sensing and Spatial Modeling Approaches for Land Evaluation in Dry Wadis, Eastern Desert, Egypt

Belal A.A,Mohamed E.S.,Shalaby A. 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Parametric study of shear strength of CFRP strengthened end-web panels

Haitham A. Shalaby,Maha M. Hassan,Sherif S. Safar 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.2

Strengthening of civil infrastructure with advanced composites have recently become one of the most popular methods. The use of Fiber Reinforced Polymer (FRP) strips plates and fabric for strengthening of reinforced concrete structures has well established design guidelines and standards. Research on the application of FRP composites to steel structures compared to concrete structures is limited, especially for shear strengthening applications. Whereas, there is a need for cost-effective system that could be used to strengthen steel high-way bridge girders to cope with losses due to corrosion in addition to continuous demands for increasing traffic loads. In this study, a parametric finite element study is performed to investigate the effect of applying thick CFRP strips diagonally on webs of plate girders on the shear strength of end-web panels. The study focuses on illustrating the effect of several geometric parameters on nominal shear strength. Hence, a formula is developed to determine the enhancement of shear strength gained upon the application of CFRP strips.

The Effect of Feeding Mannan-Oligosaccharides (Bio-MOS) on the Performance of Meat Chickens under Two Different Vaccination Programs

Shafey, T.M.,Al-Mufarej, S.,Shalaby, M.I.,Jarelnabi, A.J. Asian Australasian Association of Animal Productio 2001 Animal Bioscience Vol.14 No.4

The effects of feeding a mannan oligosaccharide (Bio-Mos) from 0 to 3 g/kg diet and vaccination program on 1- to 35-day performance (growth and feed efficiency), metabolizable energy, nitrogen utilization and carcass composition of meat chickens were investigated. A general vaccination program was used against IB, IBD and ND with half of the birds per diet receiving a booster dose of IB and ND vaccines at 12 days of age. Dietary supplementation of Bio-Mos (BM) did not influence body weight gain, feed efficiency and nutrient utilization. The highest dietary BM (3 versus 1.5 or 0 g/kg) increased carcass abdominal fat and reduced the proportion of drumstick in the carcass of meat chickens. The booster dose reduced the performance of birds. It was concluded that the addition of BM to the diet of chickens did not significantly influence the performance and nutrient utilization of meat chickens.

Effect of β-Blocker Inhibitors on Aluminum Corrosion

Fouda, A. S.,El-Ewady, G. Y.,Shalabi, K. Korean Chemical Society 2011 대한화학회지 Vol.55 No.2

베타 차단제 억제제(atenolol, propranolol, timolol and nadolol)의 존재와 부존 하에서 0.1M HCl 용액에 담긴 알루미늄의 부식작용을 연구하였다. 이 연구에 무게감량, 변전위 편극, 전기화학 임피던스 분석법이 사용되었다. 억제 효과는 억제제의 농도 증가에 따라 증가하였으며, 온도가 증가함에 따라 감소하였다. 모든 억제제들은 Frumkin 등온을 따르는 알루미늄 표면에 흡착되었다. 부식반응은 전하이동과정에 의해 조절됨을 발견하였다. 억제 효과 측정을 위해 사용된 실험방법 들에 대해 조사한 결과 모두 억제효과가 우수하였다. Corrosion of aluminum in 0.1 M HCl solution in the absence and presence of ${\beta}$-blocker inhibitors (atenolol, propranolol, timolol and nadolol) was investigated using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The inhibition efficiency increased with inhibitor concentration and decreased with rise of temperature. Potentiodynamic polarization curves revealed that they acted as cathodic inhibitors. Some thermodynamic parameters were calculated and discussed. All inhibitors were adsorbed on Al surface obeying Frumkin isotherm. All EIS tests exhibited one capacitive loop which indicates that the corrosion reaction is controlled by charge transfer process. The inhibition efficiencies of all test methods were in good agreement.

Assessment of Wind Energy based on Optimal Weibull Parameters Estimation using Bald Eagle Search Algorithm: Case Studies from Egypt

Abou El-Ela Adel A.,El-Sehiemy Ragab A.,Shaheen Abdullah M.,Shalaby Ayman S. 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.6

As the wind speed is intermittent and unpredictable, statistical distribution approaches have been used to describe wind dates. The Weibull distribution with two parameters is thought to be the most accurate way for modeling wind data. This study seeks wind energy assessment via searching for optimal parameter estimation of the Weibull distribution. For this target, several analytical and heuristic methods are investigated. The analytical methods such as maximum likelihood method, moment method, energy pattern factor method (EPFM), and empirical method (EM) are used to find these optimal parameters. Also, these parameters are obtained by four heuristic optimization algorithms called particle swarm, crow search, aquila optimizer, and bald eagle search optimizers. The simulation results of analytical and heuristics are assessed together to identify the best probability density function (PDF) of wind data. In addition, these competitive models are submitted to find the most appropriate model to represent wind energy production. In all methods, the error between actual and estimated wind energy density is computed as the target fitness function. The simulation tests are carried out based on per year real data that are collected from Zafaranah and Shark El-Ouinate sites in Egypt. Also, different indicators of fitness properties are assessed such as the root mean square error (RMSE), determination coefficient (R2), mean absolute error (MAE), and wind production deviation (WPD). The simulation results declare that the proposed bald eagle search optimization algorithm offers greater accuracy than other analytical and heuristic algorithms in estimating the Weibull parameters. Besides, statistical analysis of the compared methods demonstrates the high stability of the BES algorithm. Moreover, the BES algorithm presents the fastest convergence compared to the others. Furthermore, different models are analyzed to deduce the nonlinear relationship between the wind output power and the regarding speed where the error of wind energy density between actual and estimated is greatly minimized using the cubic model at least values of statistical indicators.