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DERIVATIVE SAmPLING EXPANSIONS FOR THE LINEAR CANONICAL TRANSFORm:CONVERGENCE AND ERROR ANALYSIS

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Journal of Computational mathematics 2019年第3期37卷 403-418页

作者： mahmoud H.Annaby rashad m.asharabi Department of mathematics Faculty of ScienceCairo University12613 GizaEgypt Department of mathematics College of Arts and SciencesNajran UniversitySaudi Arabia

In recent decades,the fractional Fourier transform as well as the linear canonical transform became very efficient tools in a variety of approximation and signal processing *** are many literatures on sampling expansions of interpolation type for bandlimited functions in the sense of these ***,rigorous studies on convergence or error analysis are *** is our aim in this paper to establish sampling expansions of interpolation type for bandlimited functions and to investigate their convergence and error *** particular,we introduce rigorous error estimates for the truncation error and both amplitude and jitter-time errors.

关键词： Linear canonical transform Sampling theorems Truncation error Amplitude error Jitter-time error

Double sampling derivatives and truncation error estimates

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Applied mathematics(A Journal of Chinese Universities) 2018年第2期33卷 209-224页

作者： rashad m.asharabi Aisha m.Al-Hayzea Department of mathematics College of Arts and Sciences Najran University

This paper investigates double sampling series derivatives for bivariate functions defined on R2 that are in the Bernstein space. For this sampling series, we estimate some of the pointwise and uniform bounds when the function satisfies some decay conditions. The truncated series of this formula allow us to approximate any order of partial derivatives for function from Bernstein space using only a finite number of samples from the function itself. This sampling formula will be useful in the approximation theory and its applications, especially after having the truncation error well-established. Examples with tables and figures are given at the end of the paper to illustrate the advantages of this formula.

关键词： double sampling series truncation error bounds convergence rate

Cost-effective integrated strategy for the fabrication of hard-magnet barium hexaferrite powders from low-grade barite ore

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International Journal of minerals,metallurgy and materials 2016年第9期23卷 991-1000页

作者： m.m.S.Sanad m.m.rashad Central metallurgical R & D Institute

Ultrafine barium hexaferrite（BaFe12O19） powders were synthesized from the metallurgical extracts of low-grade Egyptian barite ore via a co-precipitation route. Hydrometallurgical treatment of barite ore was systematically studied to achieve the maximum dissolution efficiency of Fe（～99.7%） under the optimum conditions. The hexaferrite precursors were obtained by the co-precipitation of BaS produced by the reduction of barite ore with carbon at 1273 K and then dissolved in diluted HCl and FeCl3 solution at pH 10 using NaOH as a base; the product was then annealed at 1273 K in an open atmosphere. The effect of Fe^3＋/Ba^2＋ molar ratio and the addition of hydrogen peroxide（H2O2） on the phase structure, crystallite size, morphology, and magnetic properties were investigated by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. Single-phase BaFe（12）O（19） powder was obtained at an Fe^3＋/Ba^2＋ molar ratio of 8.00. The formed powders exhibited a hexagonal platelet-like structure. Good maximum magnetization（48.3 A×m^2×kg^–1） was achieved in the material prepared at an Fe^3＋/Ba^2＋ molar ratio of 8.0 in the presence of 5% H2O2 as an oxidizer and at 1273 K because of the formation of a uniform, hexagonal-shaped structure.

关键词： chemical process barite ore treatment characterization magnetic properties ferrites

Understanding the low temperature electrochemistry of magnesium-lithium hybrid ion battery in all-phenyl-complex solutions

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Journal of Energy Chemistry 2021年第5期30卷 383-390页

作者： muhammad rashad muhammad Asif School of materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003JiangsuChina Bernal Institute Department of Chemical SciencesUniversity of LimerickLimerick V94 T9PXIreland

magnesium-lithium hybrid ion batteries have emerged as a new class of energy storage systems owing to dendrite free cycling of magnesium anode and possibility of practice of numerous conventional lithium *** present work,we used hybrid ion strategy to analyze the performance of lithium titanate based lithium cathode,magnesium metal anode,and all-phenyl complex(APC)electrolytes at different temperatures(25℃,10℃,0℃,-10℃,and-20℃).The hybrid ion battery exhibited excellent rate performance(228 m Ah g^(-1)/20 m A g^(-1) and 163 mAh g^(-1)/1000 mA g^(-1))with stable voltage plateaus at 0.90 and 0.75 V,which corresponds to specific energy of 178 Wh kg^(-1) at room temperature(25℃).Experimental results revealed that APC-THF solutions have strong potential to suppress the freezing of electrolyte solutions owing to low boiling point of *** low temperature electrochemical testing revealed the reversible capacities of 213.4,165.5,143.8,133.2 and 78.56 mAh g^(-1) at 25,10,0,-10,and-20℃,***,ex-situ XRD,SEm,and EIS tests were carried out to understand the reaction kinetics of both mg2+and Li+ions inside the lithium titanate *** hope this work will shed light on low temperature prospective of electrochemical devices for use in cold environments.

关键词： mg ion battery mg-Li hybrid ion batteries Electrochemical properties Low temperature Energy storage

Investigation on high-volume fly ash pastes modified with micro-size metakaolin subjected to high temperatures

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Journal of Central South University 2020年第1期27卷 231-241页

作者： Alaa m rashad Building materials Research and Quality Control Institute Housing & Building National Research Center (HBRC) Civil Engineering Department College of engineering Shaqra University

Portland cement(PC) containing high-volume fly ash(HVFA) is usually used to obtain economical and more sustainable merits, but these merits suffer from dramatically low compressive strength especially at early ages. In this work, the possibility of using micro-size metakaolin(mSK) particles to improve the compressive strength of HVFA paste before and after subjecting to high temperatures was studied. To produce HVFA paste, cement was partially substituted with 70% fly ash(FA), by weight. After that, FA was partially substituted with mSK at ratios fluctuating from 5% to 20% with an interval of 5%, by weight. The effect of mSK on the workability of HVFA mixture was measured. After curing, specimens were subjected to different high temperatures fluctuating from 400 to 1000 ℃ with an interval of 200 ℃ for 2 h. The results were analyzed by different techniques named X-ray diffraction(XRD), thermogravimetry(TGA) and scanning electron microscopy(SEm). The results showed that the incorporation of mSK particles into HVFA mixture exhibited a negative effect on the workability and a positive effect on the compressive strength before and after firing.

关键词： high-volume fly ash micro-size metakaolin high-temperature property workability remaining compressive strength

tRNA cleavage: a new insight

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Neural Regeneration Research 2020年第1期15卷 47-52页

作者： Sherif rashad Kuniyasu Niizuma Teiji Tominaga Department of Neurosurgery Tohoku University Graduate School of MedicineSendaiJapan Department of Neurosurgical Engineering and Translational Neuroscience Tohoku University Graduate School of MedicineSendaiJapan Department of Neurosurgical Engineering and Translational Neuroscience Graduate School of Biomedical EngineeringTohoku UniversitySendaiJapan

Over the past decades,tRNA was found to be a rich hub of RNA modifications such as 1-methyladenosine and 5-methycytosine modifications and others,holding more than half of all modifications occurring in RNA ***,tRNA was discovered to be a source of various small noncoding RNA species,such as the stress induced angiogenin cleaved tRNA halves(tiRNA)or the miRNA like tRNA derived *** cleavage under stress was fist discovered in bacteria and later was found to be conserved across different species,including *** cellular stress conditions,tRNA undergoes conformational changes and angiogenin cleaves it into 3′and 5′halves.5′tiRNA halves were shown to repress protein *** cleavage is thought of to be a cytoprotective mechanism by which cells evade apoptosis,however some data hints to the opposite;that tiRNA are cytotoxic or at least related to apoptosis *** cleavage also was shown to be affected by tRNA modifications via different enzymes in the cytosol and *** this review,we will highlight the biology of tRNA cleavage,show the evidence of it being cytoprotective or a marker of cell death and shed a light on its role in disease models and human diseases as well as possible future directions in this field of RNA research.

关键词： angiogenin apoptosis cell stress RNA modification stress granules stroke tiRNA translation repression tRNA tRNA cleavage

Efect of Thermal Annealing on the Physical Properties of Zn_(1-x)Cu_xSe Thin Films Deposited by Close Spaced Sublimation Technique

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Acta metallurgica Sinica(English Letters) 2013年第6期26卷 699-706页

作者： muhammad Arslan Riaz muhammad Arshad mahmood rashad Rasheed Department of Applied Physics Federal Urdu University of ArtsSciences and Technology National Institute of Lasers and Optronics

Thin films of Zn1-xCuxSe （x= 0.00, 0.05, 0.10, 0.15, 0.20） were grown on glass substrates by closed space sublimation technique. The deposited films were annealed at 200 ~C and 400 ~C in air for 1 h. The annealed samples have been investigated through Rutherford backscattering spectroscopy （RBS）, X-ray diffraction （XRD）, spectroscopic ellipsometer, spectrophotometer and Raman spectroscopy. Through RBS, the composition of the films was calculated and compared with the initial concentration. Structural characteriza- tion including crystal structure, crystal orientation, lattice parameter, grain size, strain and dislocation density were carried out using XRD data. From XRD spectra it was revealed that the as-deposited and annealed films were polycrystalline in nature with zinc-blende structure. However, the crystallinity and the grain size were improved with the increase of annealing temperature. According to Raman spectroscopy, it was observed that as deposited and annealed samples have the same characteristic vibrational modes of ZnSe at low and high frequency optical phonon modes while another mode was observed for 400 ℃ annealed samples at 745 cm-1. Spectroscopic ellipsometer has been used to found annealing effect on the optical properties of ZnSe. The band gap energy has been determined using transmission spectra. It was found that the band gap energy of the film increased with the increase of annealing temperature.

关键词： Closed space sublimation Annealing effect Structural Transmission Band gap Spectroscopic ellipsometer Raman spectroscopy

Conjugate natural convection of non-Newtonian hybrid nanofluid in wavy-shaped enclosure

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Applied mathematics and mechanics(English Edition) 2022年第3期43卷 447-466页

作者： S.HUSSAIN T.TAYEBI T.ARmAGHANI A.m.rashad H.A.NABWEY Department of mathematics Capital University of Science and TechnologyIslamabad 44000Pakistan Lehrstuhl III Department of MathematicsTechnical University of DortmundDortmund 44227Germany Faculty of Sciences and Technology University of Bordj Bou ArreridjEl-Anasser 34030Algeria Department of Engineering West Tehran BranchIslamic Azad UniversityTehran 11365Iran Department of mathematics Aswan UniversityFaculty of ScienceAswan 81528Egypt Department of mathematics College of Science and Humanities in Al-KharjPrince Sattam Bin Abdulaziz UniversityAl-Kharj 11942Saudi Arabia Department of Basic Engineering Science Faculty of EngineeringMenou¯a UniversityShebin El-Kom 32511Egypt

The present study concerns the modelization and numerical simulation for the heat and flow exchange characteristics in a novel configuration saturated with a nonNewtonian Ag-mgO hybrid *** wavy shaped enclosure is equipped with onequarter of a conducting solid *** system of equations resulting from the mathematical modeling of the physical problem in its dimensionless form is discretized via the higher-order Galerkin-based finite element method(GFEm).The dependency of various factors and their interrelationships affecting the hydro-thermal behavior and heat exchange rate are *** numerical experiments reveal that the best heat transfer rate is achieved for the pseudo-plastic hybrid nanoliquid with high Rayleigh number and thermal conductivity ratio and low Hartmann ***,the power-law index has a major effect in deteriorating the heat convection at high Rayleigh number.

关键词： natural convection waved-shaped cavity magnetic field hybrid nanofluid higher order finite element method(FEm)

Activation Functions Effect on Fractal Coding Using Neural Networks

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Intelligent Automation & Soft Computing 2023年第4期36卷 957-965页

作者： rashad A.Al-Jawfi Department of mathematics Faculty of Sciences and ArtsNajran UniversityKSA

Activation functions play an essential role in converting the output of the artiﬁcial neural network into nonlinear results,since without this nonlinearity,the results of the network will be less *** is the mission of all nonlinear functions,except for *** activation function must be dif-ferentiable for backpropagation *** study’s objective is to determine the best activation functions for the approximation of each fractal *** results have been attained using matlab and Visual Basic programs,which indi-cate that the bounded function is more helpful than other *** non-lin-earity of the activation function is important when using neural networks for coding fractal images because the coefﬁcients of the Iterated Function System are different according to the different types of *** most commonly cho-sen activation function is the sigmoidal function,which produces a positive *** functions,such as tansh or arctan,whose values can be positive or negative depending on the network input,tend to train neural networks *** coding speed of the fractal image is different depending on the appropriate activation function chosen for each fractal *** this paper,we have provided the appro-priate activation functions for each type of system of iterated functions that help the network to identify the transactions of the system.

关键词： Activation function fractal coding iterated function system