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The effect of a magnetic field on a 2D problem of fibre-reinforced thermoelasticity rotation under three theories

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Chinese Physics B 2012年第6期21卷 264-275页

作者： Kh.lotfy Department of Mathematics Faculty of ScienceZagazig UniversityZagazigP.O.Box 44519Egypt Department of Mathematics Faculty of Science and ArtsAl-mithnabQassim UniversityP.O.Box 931Buridah 51931Al-mithnabKingdom of Saudi Arabia

In the present paper, we introduce the coupled theory （CD）, Lord-Schulman （LS） theory, and Green-Lindsay （GL） theory to study the influences of a magnetic field and rotation on a two-dimensional problem of fibre-reinforced thermoelasticity. The material is a homogeneous isotropic elastic half-space. The method applied here is to use normal mode analysis to solve a thermal shock problem. Some particular cases are also discussed in the context of the problem. Deformation of a body depends on the nature of the force applied as well as the type of boundary conditions. Numerical results for the temperature, displacement, and thermal stress components are given and illustrated graphically in the absence and the presence of the magnetic field and rotation.

关键词： Lord-Schulman theory Green-Lindsay theory coupled theory reinforcement rotation,magnetic field

The effect of rotation on plane waves in generalized thermo-microstretch elastic solid with one relaxation time for a mode-I crack problem

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Chinese Physics B 2011年第7期20卷 266-278页

作者： Kh.lotfy Mohamed I.A.Othman Department of Mathematics Faculty of ScienceZagazig UniversityP.O.Box 44519ZagazigEgypt Department of Mathematics Faculty of SciencealmithnabQassim UniversityP.O.Box 6666AlmithnabKingdom of Saudi Arabia

The present paper is aimed at studying the effect of rotation on the general model of the equations of the generalized thermo-microstretch for a homogeneous isotropic elastic half-space solid, whose surface is subjected to a Mode-I crack problem. The problem is studied in the context of the generalized thermoelasticity Lord Shulman＇s （L-S） theory with one relaxation time, as well as with the classical dynamical coupled theory （CD）. The normal mode analysis is used to obtain the exact expressions for the displacement components, the force stresses, the temperature, the couple stresses and the microstress distribution. The variations of the considered variables through the horizontal distance are illustrated graphically. Comparisons of the results are made between the two theories with and without the rotation and the microstretch constants.

关键词： Lord-Shulman's theory thermoelasticity microrotation microstretch

Thomson and rotation effects during photothermal excitation process in magnetic semiconductor medium using variable thermal conductivity

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Applied Mathematics and Mechanics(English Edition) 2020年第6期41卷 909-926页

作者： K.lotfy A.K.KHAMIS A.A.EL-BARY M.H.AHMED Department of Mathematics Faculty of ScienceZagazig UniversityZagazig 44519Egypt Department of Mathematics Faculty of ScienceTaibah UniversityAl-Madinah 30002Saudi Arabia Department of Mathematics Faculty of ScienceNorthern Border UniversityArar 91431Saudi Arabia Arab Academy for Science Technology and Maritime TransportAlexandria 1029Egypt

This study investigates a strong magnetic field acting over an elastic rotator semiconductor *** Thomson effect due to the magnetic field during the photothermal transport process is studied,and the thermoelectricity theory is used to explain the behavior of waves in the homogenous and isotropic medium under the effect of variable thermal *** variable thermal conductivity is considered as a linear function of the *** two-dimensional deformation equations are used to describe the overlaps among plasma,electrical,thermal,and magneto-elastic *** charge density of inertia-particles is considered as a function of time for studying the induced electric *** normal mode analysis is used to obtain the exact solutions of the physical field distributions as part of this *** obtain the complete solutions of the physical field quantities,the certain mechanical loads,electromagnetic effects,thermal effects,and plasma recombination process are applied *** results of the physical distributions are graphically depicted and discussed in consideration of the internal heat source,rotation,and Peltier coefficient.

关键词： photothermal thermal conductivity Thomson effect rotation magnetic field Peltier coefficient

Thermomagnetic effect with microtemperature in a semiconducting photothermal excitation medium

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Applied Mathematics and Mechanics(English Edition) 2018年第6期39卷 783-796页

作者： K.lotfy R.KUMAR W.HASSAN M.GABR Department of Mathematics Faculty of ScienceZagazig University Department of Mathematics Kurukshetra University Mathematics and Physics Department Faculty of EngineeringPort Said University

The main goal of this paper is to focus on the investigation of interaction between a magnetic field and elastic materials with microstructure, whose microelements possess microtemperatures with photothermal excitation. The elastic-photothermal prob- lem in one-dimension is solved by introducing photothermal excitation at the free surface of a semi-infinite semiconducting medium （semiconductor rod）. The integral transform technique is used to solve the governing equations of the problem under the effect of the microtemperature field. The analytical expressions for some physical quantities in the physical domain are obtained with the heating boundary surface and free traction. The numerical inversion technique is used to obtain the resulting quantities in the physical domain. The obtained numerical results with some comparisons are discussed and shown graphically.

关键词： photothermal theory carrier density magnetic field microtemperature Laplace transform

An Enhanced Automatic Arabic Essay Scoring System Based on Machine Learning Algorithms

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Computers, Materials & Continua 2023年第10期77卷 1227-1249页

作者： Nourmeen lotfy Abdulaziz Shehab Mohammed Elhoseny Ahmed Abu-Elfetouh Department of Information Systems Faculty of Computers and Information ScienceMansoura UniversityMansoura35516Egypt Department of Information Systems College of Computer and Information SciencesJouf UniversitySakakaSaudi Arabia College of Computing and Informatics University of SharjahSharjahUnited Arab Emirates

Despite the extensive effort to improve intelligent educational tools for smart learning environments,automatic Arabic essay scoring remains a big research *** nature of the writing style of the Arabic language makes the problem even more *** study designs,implements,and evaluates an automatic Arabic essay scoring *** proposed system starts with pre-processing the student answer and model answer dataset using data cleaning and natural language processing ***,it comprises two main components:the grading engine and the adaptive fusion *** grading engine employs string-based and corpus-based similarity algorithms *** that,the adaptive fusion engine aims to prepare students’scores to be delivered to different feature selection algorithms,such as Recursive Feature Elimination and ***,some machine learning algorithms such as Decision Tree,Random Forest,Adaboost,Lasso,Bagging,and K-Nearest Neighbor are employed to improve the suggested system’s *** experimental results in the grading engine showed that Extracting DIStributionally similar words using the CO-occurrences similarity measure achieved the best correlation ***,in the adaptive fusion engine,the Random Forest algorithm outperforms all other machine learning algorithms using the(80%–20%)splitting method on the original *** achieves 91.30%,94.20%,0.023,0.106,and 0.153 in terms of Pearson’s Correlation Coefficient,Willmot’s Index of Agreement,Mean Square Error,Mean Absolute Error,and Root Mean Square Error metrics,respectively.

关键词： Arabic corpus-based similarity correlation machine learning string-based similarity text similarity

Reduced differential transform and Sumudu transform methods for solving fractional financial models of awareness

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Applied Mathematics(A Journal of Chinese Universities) 2023年第3期38卷 338-356页

作者： A.M.S.Mahdy K.A.Gepreel Kh.lotfy A.El-Bary Department of Mathematics and Statistics College of ScienceTaif UniversityP.O.Box 11099Taif21944Saudi Arabia Department of Mathematics Faculty of ScienceZagazig UniversityP.O.Box 44519ZagazigEgypt Arab Academy for Science Technology and Maritime Transport1029AlexandriaEgypt

In that paper,we new study has been carried out on previous studies of one of the most important mathematical models that describe the global economic movement,and that is described as a non-linear fractional financial model of awareness,where the studies are represented at the steps following:One:The schematic of the model is ***:The disease-free equilibrium point(DFE)and the stability of the equilibrium point are ***:The stability of the model is fulfilled by drawing the Lyapunov exponents and Poincare ***:The existence of uniformly stable solutions have ***:The Caputo is described as the fractional ***:Fractional optimal control for NFFMA is discussed by clarifying the fractional optimal control through drawing before and after ***:Reduced differential transform method(RDTM)and Sumudu Decomposition Method(SDM)are used to take the resolution of an ***,we display that SDM and RDTM are highly identical.

关键词： financial of awareness stability Lyapunov exponents Poincare map fractional optimal control Hamiltonian

Mode-I crack in a two-dimensional fibre-reinforced generalized thermoelastic problem

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Chinese Physics B 2012年第1期21卷 244-253页

作者： Kh.lotfy Department of Mathematics Faculty of ScienceZagazig UniversityZagazig P.O.Box 44519Egypt Department of Mathematics Faculty of Science and ArtsAl-mithnabQassim UniversityP.O.Box 931Buridah 51931Al-mithnabKingdom of Saudi Arabia

A general model of the equations of the Lord-Sulman theory including one relaxation time and the Green-Lindsay theory with two relaxation times, as well as the classical dynamical coupled theory, are applied to the study of the influence of reinforcement on the total deformation for an infinite space weakened by a finite linear opening mode- I crack. We study the influence of reinforcement on the total deformation of rotating thermoelastic half-space and their interaction with each other. The material is homogeneous isotropic elastic half space. The crack is subjected to prescribed temperature and stress distributions. The normal mode analysis is used to obtain the exact expressions for displacement components, force stresses, and temperature. The variations of the considered variables with the horizontal distance are illustrated graphically. Comparisons are made with the results obtained in the three theories with and without rotation. A comparison is also made between the two theories for different depths.

关键词： mode-I crack Lord -Sulman theory thermoelasticity normal mode analysis.

Effective participation of wind turbines in frequency control of a two-area power system using coot optimization

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Protection and Control of Modern Power Systems 2023年第1期8卷 230-244页

作者： Mahmoud Hussain El-Bahay Mohammed Elsayed lotfy Mohamed A.El-Hameed Electrical Power and Machines Department Faculty of EngineeringZagazig UniversityZagazig 44519Egypt ECEN Department Faculty of EngineeringA’Sharqiyah University400 IbraOman

In this paper,load frequency control is performed for a two-area power system incorporating a high penetration of renewable energy sources.A droop controller for a type 3 wind turbine is used to extract the stored kinetic energy from the rotating masses during sudden load *** auxiliary storage controller is applied to achieve effec-tive frequency *** coot optimization algorithm(COA)is applied to allocate the optimum parameters of the fractional-order proportional integral derivative(FOPID),droop and auxiliary storage *** fitness function is represented by the summation of integral square deviations in tie line power,and Areas 1 and 2 frequency *** robustness of the COA is proven by comparing the results with benchmarked optimizers including:atomic orbital search,honey badger algorithm,water cycle algorithm and particle swarm *** assessment is confirmed in the following four scenarios:(i)optimization while including PID controllers;(ii)optimization while including FOPID controllers;(iii)validation of COA results under various load disturbances;and(iv)validation of the proposed controllers under varying weather conditions.

关键词： Coot optimizer FOPID Load frequency control Photovoltaic Variable speed wind turbine

Influences of poly (vinyl alcohol) molecular weight and carbon nanotubes on radiation crosslinking shape memory polymers

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Progress in Natural Science:Materials International 2017年第3期27卷 316-325页

作者： Aamer A.M.Alfayyadh S.lotfy A.A.Basfar Mutasim I.Khalil Radiation Technology Center Nuclear Science Research InstituteKing Abdulaziz City for Science and Technology(KACST) Polymer Chemistry Department National Center for Radiation Research and TechnologyAtomic Energy Authority Department of Chemistry Faculty of ScienceKing Saud University

Polyvinyl alcohol（PVA） of two molecular weights was used to prepare shape memory polymers based on chemical-crosslinking by *** chemical-crosslinking was done in the presence of 2-carboxyethvl acrylate oligomers（CEA） and nano-filler[multi-wall carbon nanotubes（MWCNT） and functionalized carbon nanotubes（MWCNT-NH;）]followed by radiation-induced *** analysis of the material revealed an increase in the gel fraction and a significant reduction in swelling of the nanocomposite material that was crosslinked with both glutaraldehyde and ionizing *** radiation crosslinked nanocomposites demonstrated approximately a 90%gelation over a range of 50-300 kGy irradiation *** scanning electron microscopy（SEM） analysis showed a homogeneous distribution of nanocomposites in the composite *** thermal properties of radiation crosslinked（PVA/CEA） and（PVA-CEA）-nano-fillers were investigated by a thermogravimetric analysis（TGA）.The mechanical properties were examined via dynamic mechanical analysis（DMA） which showed significant variation because of the addition of *** radiation crosslinked materials show good shape memory behavior that may be useful in many applications based on the range of temperatures at which Tan 8 appears.

关键词： Shape memory polymers Radiation Poly(vinyl alcohol) Nanocomposite materials