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Applied Mathematics and Mechanics(English Edition) 2005年第4期26卷 470-475页

作者： hamdy M.youssef Mathematical Department Faculty of Engineering Umm Al_Qura UniversityMakkah Al_Mokaramah P.5555 Saudi Arabia

The equations of generalized thermoelasticity with one relaxation time with variable modulus of elasticity and the thermal conductivity were used to solve a problem of an infinite material with a spherical *** inner surface of the cavity was taken to be traction free and acted upon by a thermal shock to the surface. Laplace transforms techniques were used to obtain the solution by a direct *** inverse Laplace transforms was obtained *** temperature,displacement and stress distributions are represented graphically.

关键词： thermoelasticity generalized thermoelasticity modulus of elasticity thermal conductivity

State-space approach to vibration of gold nano-beam induced by ramp type heating

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Nano-Micro Letters 2010年第3期2卷 139-147页

作者： hamdy M.youssef Khaled A.Elsibai Mathematical Department-Faculty of Education-Alexandria University-Egypt Mathematics Department Faculty of ScienceMansoura University

In the nanoscale beam,two effects become *** is the non-Fourier effect in heat conduction and the other is the coupling effect between temperature and strain *** the present study,a generalized solution for the generalized thermoelastic vibration of gold nano-beam resonator induced by ramp type heating is *** solution takes into account the above two ***-space and Laplace transform methods are used to determine the lateral vibration,the temperature,the displacement,the stress and the strain energy of the *** effects of the relaxation time and the ramping time parameters have been studied.

关键词： Thermoelasticity Euler-Bernoulli equation Gold nano-beam Ramp type heating

On the Application of the Adomian’s Decomposition Method to a Generalized Thermoelastic Infinite Medium with a Spherical Cavity in the Framework Three Different Models

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Fluid Dynamics & Materials Processing 2019年第5期15卷 597-611页

作者： Najat A.Alghamdi hamdy M.youssef Mathematics Department Faculty of ScienceUmm Al-Qura UniversityMakkahSaudi Arabia Mathematics Department Faculty of EducationAlexandria UniversityAlexandriaEgypt Mathematics Department Faculty of EngineeringUmm Al-Qura UniversityMakkahSaudi Arabia

A mathematical model is elaborated for a thermoelastic infinite body with a spherical cavity.A generalized set of governing equations is formulated in the context of three different models of thermoelasticity:the Biot model,also known as“coupled thermoelasticity”model;the Lord-Shulman model,also referred to as“generalized thermoelasticity with one-relaxation time”approach;and the Green-Lindsay model,also called“generalized thermoelasticity with two-relaxation times”*** Adomian’s decomposition method is used to solve the related mathematical *** bounding plane of the cavity is subjected to harmonic thermal loading with zero heat flux and *** results for the temperature,radial stress,strain,and displacement are represented *** is shown that the angular thermal load and the relaxation times have significant effects on all the studied fields.

关键词： Adomian’s decomposition method generalized thermoelasticity relaxation time iteration method

Study on the SEIQR model and applying the epidemiological rates of COVID-19 epidemic spread in Saudi Arabia

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Infectious Disease Modelling 2021年第1期6卷 678-692页

作者： hamdy youssef Najat Alghamdi Magdy A.Ezzat Alaa A.El-Bary Ahmed M.Shawky Mechanical Engineering Department College of Engineering and Islamic ArchitectureUmm Al-Qura UniversityMakkahSaudi Arabia Department of Mathematics Faculty of Applied ScienceUmm Al-Qura UniversityMakkahSaudi Arabia College of Science and Arts Qassim UniversityAl BukairiyahAl QassimSaudi Arabia Arab Academy for Science Technology and Maritime TransportP.O.Box 1029AlexandriaEgypt Science and Technology Unit(STU) Umm Al-Qura UniversityMakkahSaudi Arabia National Committee for Mathematics Academy of Scientific Research and TechnologyEgypt

This article attempts to establish a mathematical epidemic model for the outbreak of the new COVID-19 coronavirus.A new consideration for evaluating and controlling the COVID-19 outbreak will be constructed based on the SEIQR Pandemic *** this paper,the real data of COVID-19 spread in Saudi Arabia has been used for the mathematical model and dynamic *** the new reproductive number and detailed stability analysis,the dynamics of the proposed SEIQR model have been *** local sensitivity of the reproduction number has been *** domain of solution and equilibrium based on the SEIQR model have been proved using a Jacobian linearization *** state of equilibrium and its significance have been proved,and a study of the integrity of the disease-free equilibrium has been carried *** Lyapunov stability theorem demonstrated the global stability of the current model *** SEIQR model has been numerically validated and projected by contrasting the results from the SEIQR model with the actual COVID-19 spread data in Saudi *** result of this paper shows that the SEIQR model is a model that is effective in analyzing epidemic spread,such as *** the end of the study,we have implemented the protocol which helped the Saudi population to stop the spread of COVID-19 rapidly.

关键词： COVID-19 Jacobian matrix Lyapunov stability Reproduction number SEIR model SEIQR model

Two Temperature Heat Flux of Semi Infinite Piezoelectric Ceramic Rod

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Engineering（科研） 2013年第3期5卷 277-291页

作者： Essam Bassiouny Refaat Sabry hamdy youssef Faculty of Science and Humanitarian Studies Salman Bin Abdulaziz University Al-Kharj KSA Mechanical Engineering Department Faculty of Engineering and Islamic Architecture Umm Al-Qura University Mecca KSA

The theory of two-temperature generalized thermoelasticity is used to solve the problem of heating a semi-infinite rod made of a piezoelectric ceramic material within the framework of generalized thermopiezoelasticity theory by supplying the rod a certain amount of heat uniformly distributed over a finite time period to the finite end of the rod. The Laplace transform formalism is used to solve the proposed model. Inverse Laplace transforms are computed numerically using a method based on Fourier expansion techniques. The physical parameters (i.e., conductive temperature, dynamical temperature, stress, strain, and displacement distributions) are investigated graphically.

关键词： Two Temperatures Generalized Thermoelasticity Thermopiezoelasticity Thermal Waves Ceramics Piezoelectric Materials—Heat Flux

Vibration of Nano Beam Induced by Ramp Type Heating

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World Journal of Nano Science and Engineering 2011年第2期1卷 37-44页

作者： hamdy M. youssef Khaled A. Elsibai 不详

The non-Fourier effect in heat conduction and the coupling effect between temperature and strain rate, became the most significant effects in the nano-scale beam. In the present study, a generalized solution for the generalized thermoelastic vibration of a bounded nano-beam resonator induced by ramp type of heating is developed and the solutions take into account the above two effects. The Laplace transforms and direct method are used to determine the lateral vibration, the temperature, the displacement, the stress and the energy of the beam. The effects of the relaxation time and the ramping time parameters have been studied with some comparisons.

关键词： Thermoelasticity Nano-Beam Ramp-Type Heating Non-Fourier Heat Conduction

Fractional Order Generalized Thermoelastic Infinite Medium with Cylindrical Cavity Subjected to Harmonically Varying Heat

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Engineering（科研） 2011年第1期3卷 32-37页

作者： hamdy M. youssef Eman A. Al-Lehaibi 不详

In this work, a mathematical model of an elastic material with cylindrical cavity will be constructed. The governing equations will be taken into the context of the fractional order generalized thermoelasticity theory (youssef 2010). Laplace transform and direct approach will be used to obtain the solution when the boundary of the cavity is exposed to harmonically heat with constant angular frequency of thermal vibration. The inverse of Laplace transforms will be computed numerically using a method based on Fourier expansion techniques. Some comparisons have been shown in figures to present the effect of the fractional order parameter and the angular frequency of thermal vibration on all the studied felids.

关键词： Thermoelasticity Generalized Thermoelasticity Fractional Order Cylindrical Cavity Harmonically Heat

Vibration of Gold Nano-Beam with Variable Young’s Modulus Due to Thermal Shock

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World Journal of Nano Science and Engineering 2015年第4期5卷 194-203页

作者： Eman A. N. Al-Lehaibi hamdy M. youssef Mathematics Department College of Science and Arts-Sharoura Najran University Najran KSA Mechanics Department Faculty of Engineering Umm Al-Qura University Makkah KSA

In this paper, we will study the most important effects in the nano-scale resonator: the coupling effect of temperature and strain rate, and the non-Fourier effect in heat conduction. A solution for the generalized thermoelastic vibration of nano-resonator induced by thermal loading has been developed. The Young’s modulus is taken as a linear function of the reference temperature. The effects of the thermal loading and the reference temperature in all the studied fields have been studied and represented in graphs with some comparisons. The Young’s modulus makes significant effects on all the studied fields where the values of the temperature, the vibration of the deflection, stress, displacement, strain, stress-strain energy increase when the Young’s modulus has taken to be variable.

关键词： Thermoelasticity Euler-Bernoulli Equation Goldnano-Beam Young’s Modulus

Generalized Thermoelasticity Problem of Material Subjected to Thermal Loading Due to Laser Pulse

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Applied Mathematics 2012年第2期3卷 142-146页

作者： hamdy M. youssef Ahmed S. Al-Felali Mathematical Department Faculty of Sciences Umm Al-Qura University Makkah Saudi Arabia Mechanical Department Faculty of Engineering and Islamic Architecture Umm Al-Qura University Makkah Saudi Arabia

This work is devoted to a study of the induced temperature and stress fields in an elastic half space in context of clas-sical coupled thermoelasticity and generalized thermoelasticity in a unified system of equations. The half space is con-sidered to be made of an isotropic homogeneous thermoelastic material. The bounding plane surface is heated by a non-Gaussian laser beam with pulse duration of 2 ps. An exact solution of the problem is first obtained in Laplace transform space. Since the response is of more interest in the transient state, the inversion of Laplace transforms have been carried numerically. The derived expressions are computed numerically for copper and the results are presented in graphical form.

关键词： Thermoelasticity Coupled Thermoelasticity Generalized Thermoelasticity Non-Gaussian Laser Pulse

Rapid Identification of Methicillin Resistant <i>Staphylococcus aureus</i>Using Real Time PCR

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Advances in Infectious Diseases 2013年第1期3卷 44-49页

作者： Said Abbadi hamdy youssef Dalal Nemenqani Ahmed S. Abdel-Moneim Microbiology Department College of Medicine Taif University Al-Taif Saudi Arabia Pathology Department College of Medicine Taif University Taif University Al-Taif Saudi Arabia

Screening for colonization with methicillin resistant Staphylococcus aureas (MRSA) is a key aspect of infection control to limit the nosocomial spread of this organism. Current methods for the detection of MRSA in clinical microbiology laboratories using conventional methods is time consuming. In this research we are trying to evaluate the use of real time PCR for the detection of MRSA. The PCR assay was evaluated in clinical isolates of MRSA (n = 45) and methicillin susceptible Staphylococcus aureas MSSA (n = 10). The diagnostic values of the assay showed high sensitivity and specificity. This real-time PCR assay proved to be a fast, sensitive and specific tool for MRSA detection in a routine microbiological laboratory. Real-time PCR now is available in all laboratories so its use in identification of MRSA will help in shortening the period for MRSA identification and will help in the success of infection control programs in hospitals.

关键词： Diagnosis MRSA Rapid Detection Real-Time PCR Staphylococcus aureus