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LOWER BOUNDs FOR sUP+INF AND sUP*INF AND AN EXTENsION OF CHEN-LIN REsULT IN DIMENsION 3

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Acta Mathematica scientia 2008年第4期28卷 749-758页

作者： samy skander Bahoura Department of Mathematics Patras University

We give two results about Harnack type inequalities. First, on Riemannian surfaces, we have an estimate of type sup ＋ inf. The second result concern the solutions of prescribed scalar curvature equation on the unit ball of Rn with Dirichlet condition. Next, we give an inequality of type （supK ^u）^2s-1 × infπu ≤ c for positive solutions of △u = V u^5 on Ω belong toR^3, where K is a compact set of Ω and V is s-Holderian, s ∈] - 1/2, 1]. For the case s = 1/2 and Ω = s3, we prove that, if minΩ u 〉 m 〉 0 （for some particular constant m 〉 0）, and the H¨olderian constant A of V tends to 0 （in certain meaning）, we have the uniform boundedness of the supremum of the solutions of the previous equation on any compact set of Ω.

关键词： sup × inf sup + inf Harnack inequality moving-plane method

EULER sCHEME FOR FRACTIONAL DELAY sTOCHAsTIC DIFFERENTIAL EQUATIONs BY ROUgH PATHs TECHNIQUEs

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Acta Mathematica scientia 2019年第3期39卷 747-763页

作者： Johanna gARZON samy TINDEL soledad TORREs Departamento de Matematicas Universidad Nacional de ColombiaBogota D.C.Colombia Department of Mathematics Purdue University150 N.University StreetW.LafayetteIN 47907USA Facultad de Ingenierza CIMF AV Universidad de ValparaisoCasilla 123-V4059 ValparaisoChile

In this note, we study a discrete time approximation for the solution of a class of delayed stochastic differential equations driven by a fractional Brownian motion with Hurst parameter H ∈(1/2,1). In order to prove convergence, we use rough paths techniques. Theoretical bounds are established and numerical simulations are displayed.

关键词： Fractional Brownian motion stochastic differential equations rough paths,discrete time approximation

Monitoring and analysing the Emirate of Dubai’s land use/land cover chang.s.an integrated,low-cost remote sensing approach

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International Journal of Digital Earth 2018年第11期11卷 1132-1150页

作者： samy Ismail Elmahdy Mohamed Mostafa Mohameda Civil and Environmental Engineering Department College of Engineering United Arab Emirates UniversityAl-AinUnited Arab Emirates Irrigation and Hydraulics Department Faculty of EngineeringCairo UniversityGizaEgypt

This study presents a modified low-cost approach,which integrates the spectral angle mapper and image difference algorithms in order to enhance classification maps for the purpose of monitoring and analysing land use/land cover change between 2000 and 2015 for the Emirate of *** approach was modified by collecting 320 training.s.mples from QuickBird imag.s.with a spatial resolution of 0.6 m,as well as carrying out field observations,followed by the application of a 3×3 soble filter,sieving classes,majority/minority analysis,and clump classes of the obtained classification *** accuracy assessment showed that the targeted 2000,2005,2010 and 2015 classification maps have 88.1252%,89.0699%,90.1225%and 96.0965%accuracy,*** results showed that the built-up area increased by 233.721 km^(2)(5.81%)between 2000 and 2005 and continues to increase even up and till the present *** assessment of chang.s.in the periods 2000–2005 and 2010–2015 confirmed that net vegetation area losses were more pronounced from 2000 to 2005 than from 2010 to 2015,dropping from 47,618 to 40,820 km^(2),*** study is aimed to assist urban planners and decision-makers,as well as research institutes.

关键词： Dubai change detection image difference sAM algorithm

Heat Transfer and Fluid Flow of Nanofluids in Laminar Radial Flow Cooling.s.stems

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Journal of Thermal science 2005年第4期14卷 362-367页

作者： gilles ROY samy Joseph PALM Cong Tam NgUYEN Faculty of Engineering Universite de MonctonMonctonNBCanadaElA 3E9

Nanofluids are considered as interesting alternatives to conventional coolants. It is well known that traditional fluids have limited heat transfer capabilities when compared to common metals. It is therefore quite conceivable that a small amount of extremely fine metallic particles placed in suspension in traditional fluids will considerably increase their heat transfer performances. A numerical investigation into the heat transfer enhancement capabilities of coolants with suspended metallic nanoparticles inside a radial, laminar flow cooling configuration is presented. Temperature dependant nanofluid properties are evaluated from experimental data available in recent literature. Results indicate that considerable heat transfer increases are possible with the use of relatively small volume fractions of nanoparticles. generally, however, these are accompanied by considerable increases in wall shear-stress. Results also show that predictions obtained with temperature variable nanofluid properties yield greater heat transfer capabilities and lower wall shear stresses when compared to predictions using constant properties.

关键词： nanofluids nanoparticles heat transfer laminar flow confined radial flow.

Encapsulation Protocol for Flexible Perovskite solar Cells Enabling.s.ability in Accelerated Aging Tests

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Energy & Environmental Materials 2023年第5期6卷 432-439页

作者： Taimoor Ahmad shyantan Dasgupta samy Almosni Alina Dudkowiak Konrad Wojciechowski saule Technologies Wroclaw Technology Park11 Dunska StreetSigma Building 54-130 WrocławPoland Department of Electronics Engineering University of Rome"Tor Vergata"Via del Politecnico 100133 RomeItaly saule Research Institute Wroclaw Technology Park11 Dunska StreetSigma Building54-130 WrocławPoland Faculty of Materials Engineering and Technical Physics Poznan University of TechnologyPiotrowo 360-965 PoznanPoland

Flexible perovskite solar cells(f-PsCs)offer attractive commercial prospects in the near future,enabled by new value propositions,such as mechanical flexibility,or high specific *** long-term reliability of these devices requires appropriate encapsulation to prevent degradation caused by environmental ***,a lamination protocol is developed,incorporating adhesive materials,barrier foils,and edge sealants,which results in a robust device *** applying the developed procedure to three different perovskite solar cell configurations(p-i-n with carbon,p-i-n with silver,and n-i with carbon),fabricated with large active areas(1 cm^(2)),the universality of this approach is *** best devices preserved over 85%of the initial performance after a sequence of accelerated aging tests based on industry standards(compliant with the IEC 61215 and IEC 61646)comprised of 1400 h of damp heat,50 thermal cycles,and 10 cycles of the humidity-freeze test.

关键词： encapsulation flexible photovoltaics perovskite solar cell stability

global solutions to Nonconvex Problems by Evolution of Hamilton-Jacobi PDEs

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Communications on Applied Mathematics and Computation 2024年第2期6卷 790-810页

作者： Howard Heaton samy Wu Fung.s.anley Osher Typal Research Typal LLCLos AngelesUSA Department of Applied Mathematics and statistics Colorado School of MinesGoldenUSA Department Mathematics UCLALos AngelesUSA

Computing tasks may often be posed as optimization *** objective functions for real-world scenarios are often nonconvex and/or ***-of-the-art methods for solving these problems typically only guarantee convergence to local *** work presents Hamilton-Jacobi-based Moreau adaptive descent(HJ-MAD),a zero-order algorithm with guaranteed convergence to global minima,assuming continuity of the objective *** core idea is to compute gradients of the Moreau envelope of the objective(which is"piece-wise convex")with adaptive smoothing *** of the Moreau envelope(i.e.,proximal operators)are approximated via the Hopf-Lax formula for the viscous Hamilton-Jacobi *** numerical examples illustrate global convergence.

关键词： global optimization Moreau envelope Hamilton-Jacobi Hopf-Lax-Cole-Hopf Proximals Zero-order optimization

Preparations and spectroscopic studies on the Three New strontium(Ⅱ),Barium(Ⅱ),and Lead(Ⅱ)Carbocysteine Complexes

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光谱学与光谱分析 2021年第9期41卷 2975-2979页

作者： samy M.El-Megharbel Moamen s.Refat Department of Chemistry College of ScienceTaif UniversityP.O.Box 11099Taif 21944Saudi Arabia

Carbocisteine,also known as carbocysteine,is a mucolytic that reduces the viscosity of sputum and thus can be used to help relieve symptoms of chronic obstructive pulmonary disorder and bronchiectasis by allowing the sufferer to expel sputum more easily.A total of three new metal complexes of carbocysteine,HCcy with the metal ions sr(Ⅱ),Ba(Ⅱ),and Pb(Ⅱ)have been successfully prepared in alkaline medium in situ H_(2)O/CH_(3)OH(50/50 w/w).The complexes obtained are characterized quantitatively and qualitatively by using micro elemental analysis,FTIR spectroscopy,UV-Vis spectroscopy,X-ray powder diffraction spectroscopy,^(1)H-NMR,and conductivity *** the spectral study,all the synthesized Ccy complexes obtained as monomeric structure and the metals center moieties are six-coordinated except lead(Ⅱ)complex which existed as a four-coordinated respectively,sugg.s.ing formulas[sr(Ccy)(H_(2)O)_(2)],[Ba(Ccy)(H_(2)O)_(2)]and[Pb(Ccy)]in neutral ***,regarding both sr(Ⅱ)and Ba(Ⅱ)complexes,the aquo groups are existed inside the coordination *** infrared assignments reveal that HCcy ligand act as a bidentate ligand with the metal ions through oxygens of the deprotonated carboxylic COOH *** 1H-NMR spectrum of the[Ba(Ccy)(H_(2)O)_(2)]complex has an absent of the proton of-COOH groups upon the deprotonated of carboxylic group.

关键词： Carbocisteine FTIR XRD ^(1)H-NMR

synthesis and spectroscopic Characterizations of New Mercury(Ⅱ), Cerium(Ⅲ), and Thorium(Ⅳ) Captopril Drug Complexes

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光谱学与光谱分析 2020年第11期40卷 3649-3652页

作者： samy M.El-Megharbel Moamen s.Refat Department of Chemistry College of ScienceTaif UniversityP.O.Box 11099Taif 21944Saudi Arabia Department of Chemistry Faculty of ScienceZagazig UniversityZagazigEgypt Department of Chemistry Faculty of SciencePort Said UniversityPort SaidEgypt

In this article, three types of metal ions with different oxidation state as mercury(Ⅱ), cerium(Ⅲ) thorium(Ⅳ) have been reacted with captopril drug(CAP). The isolated solid complexes were explained using elemental analysis, conductance measurements, infrared and 1H-NMR spectroscopy as well as the thermo gravimetric(Tg/DTg) analysis. The micro analytical and spectroscopic results for all CAP complexes were agreement with the speculated structures. The stoichiometry for divalent Hg^2+, trivalent Ce^3+ and tetravalent Th(4+) metal ions with CAP ligand was established with 1∶2(M(n+):CAP) molar ratio. The qualitative analysis showed that in case of the mercury(Ⅱ) complex, the chloride ions didn't involved in the complexity, sugg.s.ing formula [Hg(CAP)2] in neutral form. However, regarding both Ce(Ⅲ) and Th(Ⅳ) complexes as [Ce(CAP)2(NO3)]·3 H2O and [Th(CAP)2(NO3)2(H2O)]·3 H2O formulas, the nitrate group is existed inside the coordination sphere. The infrared analysis data proved that CAP drug act as a bidentate ligand with the metal ions of Ce(Ⅲ) and Th(Ⅳ) through oxygen carbonyl group C=O and oxygen of the deprotonated carboxylic COOH group, while for the Hg(Ⅱ) complex, the CAP acts as a bidentate ligand through oxygen of C=O group and sulfur atom of the deprotonated -sH group. Thorium(Ⅵ) complex has a nine-coordinate geometry, while Hg(Ⅱ) and Ce(Ⅲ) have a four and six-coordination behaviors respectively. The 1H-NMR data of the CAP compound has a singlet sharp signal at 1.90 ppm due to the proton of -sH group, this peak absent in the spectrum of the Hg(Ⅱ) CAP complex upon the deprotonated of thiol group.

关键词： Captopril drug Metal ions FTIR 1H-NMR

In First Time:synthesis and spectroscopic Interpretations ofManganese(Ⅱ),Nickel(Ⅱ)and Mercury(Ⅱ)Clidinium Bromide Drug Complexes

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光谱学与光谱分析 2021年第10期41卷 3316-3320页

作者： samy M.El-Megharbel Moamen s.Refat Department of Chemistry College of ScienceTaif UniversityP.O.Box 11099Taif 21944Saudi Arabia

Clidinium is a synthetic anticholinergic agent which has been shown in experimental and clinical studies to have an antispasmodic and antisecretory effect on the g.s.rointestinal *** the muscarinic effects of acetylcholine at neurotransmitter sites after parasympathetic *** is used to treat peptic ulcer disease and to help relieve stomach or stomach cramps or cramps due to abdominal cramps,diverticulitis,and irritable bowel *** complexes of the manganese(Ⅱ),nickel(Ⅱ)and mercury(Ⅱ)with clidinium bromide drug(C_(22)H_(26)NO_(3))types[M(C_(22)H_(25)NO 3)_(2)(H_(2)O)_(4)]and[Hg(C_(22)H_(25)NO_(3))_(2)(H_(2)O)_(2)]where M=Mn(Ⅱ)and Ni(Ⅱ),have been synthesized and characterized on the basis of elemental analysis,conductivity measurements,magnetic,electronic,1H-NMR and infrared spectral *** complexes confirm to 1∶2 stoichiometry and are *** clidinium drug ligand(C_(22)H_(26)NO_(3))act as a deprotonated monovalent monodentate chelate coordinating through hydroxyl oxygen where IR spectral bands of clidinium bromide shows a band at 3226 cm^(-1)assigned to the OH group stretching frequency,this bandν(O—H)stretching vibration motion is disappeared in case of the infrared spectra of the Mn(Ⅱ),Ni(Ⅱ),and Hg(Ⅱ)complexes sugg.s.ing the involvement of the oxygen atom of the deprotonated OH group of clidinium ligand in *** band for theν(C—O)of alcoholic group of clidinium that appears at 1240 cm^(-1)has blue shifted after complexity,indicating the participation of the alcoholic group in the coordination.1H NMR spectrum for clidinium bromide show a singlet peak at 3.65 ppm due to proton of OH group which isn’t observed in the spectrum of mercury(Ⅱ)complex referring to the deprotonation of OH group and participated in the *** on electronic spectra,IR spectra and magnetic moment measurements;six coordinated octahedral structures have been proposed for the manganese and nickel(Ⅱ)complexes,while mercury(

关键词： Clidinium bromide Monovalent complex FTIR Electronic spectra XRD