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Dynamical Behaviors of Nonlinear Coronavirus (COVID-19) model with Numerical studies

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Computers, materials & Continua 2021年第4期67卷 675-686页

作者： Khaled A.Gepreel mohamed s.mohamed Hammad Alotaibi amr m.s.mahdy Department of mathematics College of ScienceTaif UniversityTaif21944Saudi Arabia Department of mathematics Zagazig UniversityZagazig44519Egypt Department of mathematics Al-Azher UniversityNasr City11884Egypt

The development of mathematical modeling of infectious diseases is a key research area in various elds including ecology and *** aim of these models is to understand the dynamics of behavior in infectious *** the new strain of coronavirus(COVID-19),there is no vaccine to protect people and to prevent its spread so ***,control strategies associated with health care,such as social distancing,quarantine,travel restrictions,can be adopted to control the pandemic of *** article sheds light on the dynamical behaviors of nonlinear COVID-19 models based on two methods:the homotopy perturbation method(HPm)and the modied reduced differential transform method(mRDTm).We invoke a novel signal ow graph that is used to describe the COVID-19 *** our mathematical studies,it is revealed that social distancing between potentially infected individuals who are carrying the virus and healthy individuals can decrease or interrupt the spread of the *** numerical simulation results are in reasonable agreement with the study *** free equilibrium and stability point for the COVID-19 model are ***,the existence of a uniformly stable solution is proved.

关键词： Nonlinear COVID-19 model equilibrium point stability existence of uniformly stable signal ow graph homotopy perturbation method reduced differential transform method

An Approximate Numerical methods for mathematical and Physical studies for Covid-19 models

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Computer systems science & Engineering 2022年第9期42卷 1147-1163页

作者： Hammad Alotaibi Khaled A.Gepreel mohamed s.mohamed amr m.s.mahdy Department of mathematics College of ScienceTaif UniversityTaif21944Saudi Arabia

The advancement in numerical models of serious resistant illnesses is a key research territory in different fields including the nature and the study of disease *** of the aims of these models is to comprehend the elements of conduction of these *** the new strain of Covid-19(Coronavirus),there has been no immunization to protect individuals from the virus and to forestall its spread so *** things being equal,control procedures related to medical services,for example,social distancing or separation,isolation,and travel limitations can be adjusted to control this *** article reveals some insights into the dynamic practices of nonlinear Coronavirus models dependent on the homotopy annoyance strategy(HPm).We summon a novel sign stream chart that is utilized to depict the Coronavirus *** the numerical investigations,it is uncovered that social separation of the possibly tainted people who might be conveying the infection and the healthy virus-free people can diminish or interrupt the spread of the *** mathematical simulation results are highly concurrent with the statistical *** free balance and dependability focus for the Coronavirus model is discussed and the presence of a consistently steady arrangement is demonstrated.

关键词： Covid-19 model optimal control existence of uniformly stable signal stream chart homotopy perturbation technique

Describe the mathematical model for Exchanging Waves Between Bacterial and Cellular DNA

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Computers, materials & Continua 2021年第9期68卷 3615-3628页

作者： mohamed s.mohamed sayed K.Elagan saad J.Almalki muteb R.Alharthi mohamed F.El-Badawy amr m.s.mahdy Department of mathematics College of ScienceTaif UniversityTaif21944Saudi Arabia microbiology and immunology Department Faculty of PharmacyUniversity of Sadat CityMenoufiya GovernorateEgypt

In this article,we have shown that bacterial DNA could act like some coils which interact with coil-like DNA of host *** decreasing the separating distance between two bacterial cellular DNA,the interaction potential,entropy,and the number of microstates of the system ***,the system gives its energy to the medium and the temperature of the host body *** could be seen as fever in *** emitting some special waves and changing the temperature of the medium,the effects of bacterial waves could be reduced and bacterial diseases could be *** investigators have shown that bacterial DNA could emit or absorb electromagnetic *** of the main experiments about bacterial waves has been done by montagnier and his *** have shown that the genomic DNA of most pathogenic bacteria includes sequences that are able to emit electromagnetic *** results have shown that wave affects the crucial physicochemical processes in both Gram-positive and Gram-negative *** emphasis in this survey is on the development of controlling model equations and computer emulation of the model equations rather than on mathematical methods for solving the model equations and differential equations of epidemics.

关键词： DNA bacteria diseases inductor magnetic field

magneto-Photo-Thermoelastic Excitation Rotating semiconductor medium Based on moisture Diffusivity

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Computer modeling in Engineering & sciences 2024年第10期141卷 107-126页

作者： Khaled Lotfy A.m.s.mahdy Alaa A.El-Bary E.s.Elidy Department of mathematics Faculty of ScienceZagazig UniversityZagazig44519Egypt Department of mathematics Faculty of ScienceTaibah UniversityMadinah42353Saudi Arabia Department of mathematics and statistics College of ScienceTaif UniversityTaif11099Saudi Arabia Arab Academy for science Technology and Maritime TransportAlexandria1029Egypt

In this research,we focus on the free-surface deformation of a one-dimensional elastic semiconductor medium as a function of magnetic field and moisture *** problem aims to analyze the interconnection between plasma and moisture diffusivity processes,as well as thermo-elastic *** study examines the photothermoelasticity transport process while considering the impact of moisture *** employing Laplace’s transformation technique,we derive the governing equations of the photo-thermo-elastic *** equations include the equations for carrier density,elastic waves,moisture transport,heat conduction,and constitutive *** stresses,thermal conditions,and plasma boundary conditions are used to calculate the fundamental physical parameters in the Laplace *** employing numerical techniques,the Laplace transform is inverted to get complete time-domain solutions for the primary physical domains under ***,thermoelastic,and thermoelectric characteristics are employed in conjunction with a graphical analysis that takes into consideration the effects of applied forces on displacement,moisture concentration,carrier density,stress due to forces,and temperature distribution.

关键词： moisture diffusivity semiconductor photothermoelastic rotation thermomechanical waves laplace transform

Evaluating transient behaviour of large-scale photovoltaic systems during lightning events using enhanced finite difference time domain method with variable cell size approach

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High Voltage 2024年第3期9卷 636-647页

作者： Ibrahim Hetita Diaa-Eldin A.mansour Yang Han Ping Yang Congling Wang mohamed m.F.Darwish matti Lehtonen amr s.Zalhaf school of mechanical and Electrical Engineering University of Electronic Science and Technology of China(UESTC)ChengduChina Electrical Power and machines Engineering Department Faculty of EngineeringHelwan UniversityCairoEgypt Electrical Power and machines Engineering Department Faculty of EngineeringTanta UniversityTantaEgypt Department of Electrical Power Engineering Faculty of EngineeringEgypt-Japan University of Science and TechnologyAlexandriaEgypt Department of Electrical Engineering Faculty of Engineering at ShoubraBenha UniversityCairoEgypt Department of Electrical Engineering and Automation School of Electrical EngineeringAalto UniversityEspooFinland

Photovoltaic(PV)arrays are usually installed in open areas;hence,they are vulnerable to lightning strikes that can result in cell degradation,complete damage,service disruption,and increased maintenance *** a result,it is imperative to develop an effective and efficient lightning protection system by evaluating the transient behaviour of PV arrays during lightning *** aim is to evaluate the transient analysis of large-scale PV systems when subjected to lightning strikes using the finite difference time domain(FDTD)*** overvoltages are calculated at various points within the mounting *** optimise the FDTD method's execution time and make it more suitable for less powerful hardware,a variable cell size approach is ***,larger cell dimensions are used in the earthing system and smaller cell dimensions are used in the mounting *** FDTD method is utilised to calculate the temporal variation of transient overvoltages for large-scale PV systems under different scenarios,including variations in the striking point,soil resistivity,and the presence of a metal *** results indicate that the highest transient overvoltages occur at the striking point,and these values increase with the presence of a PV metal frame as well as with higher soil ***,a comparison is performed between the overvoltage results obtained from the FDTD approach and the partial element equivalent circuit(PEEC)method at the four corner points of the mounting systems to demonstrate the superior accuracy of the FDTD ***,a laboratory experiment is conducted on a small-scale PV system to validate the simulation *** calculated overvoltages obtained from the FDTD and PEEC methods are compared with the measured values,yielding a mean absolute error of 5%and 11%for the FDTD and PEEC methods,respectively,thereby confirming the accuracy of the FDTD simulation model.

关键词： transient behaviour finite

High-Order spatial FDTD solver of maxwell’s Equations for Terahertz Radiation Production

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Journal of Applied mathematics and Physics 2024年第4期12卷 1028-1042页

作者： Abdelrahman mahdy Department of Physical sciences College of Science Jazan University Jazan Kingdom of Saudi Arabia

We applied a spatial high-order finite-difference-time-domain (HO-FDTD) scheme to solve 2D maxwell’s equations in order to develop a fluid model employed to study the production of terahertz radiation by the filamentation of two femtosecond lasers in air plasma. We examined the performance of the applied scheme, in this context, we implemented the developed model to study selected phenomena in terahertz radiation production, such as the excitation energy and conversion efficiency of the produced THz radiation, in addition to the influence of the pulse chirping on properties of the produced radiation. The obtained numerical results have clarified that the applied HO-FDTD scheme is precisely accurate to solve maxwell’s equations and sufficiently valid to study the production of terahertz radiation by the filamentation of two femtosecond lasers in air plasma.

关键词： The Finite-Difference-Time-Domain Terahertz Radiation Production Filamentation of Femtosecond Laser maxwell’s Equations solution

multi-timescale modeling and Dynamic stability Analysis for sustainable microgrids:state-of-the-art and Perspectives

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Protection and Control of modern Power systems 2024年第3期9卷 1-35页

作者： mingyue Zhang Yang Han Yuxiang Liu amr s.Zalhaf Ensheng Zhao Karar mahmoud mohamed m.F.Darwish Frede Blaabjerg the school of mechanical and Electrical Engineering University of Electronic Science and Technology of ChinaChengdu 611731China IEEE 不详 the University of Electronic science and Technology of China(UEsTC) ChengduChina Aswan University the school of Electrical Engineering Aalto UniversityFinland the Department of Electrical Engineering Faculty of Engineering at ShoubraBenha University the Department of EEA School of Electrical EngineeringAalto University

The increasing trend for integrating renewable energy sources into the grid to achieve a cleaner energy system is one of the main reasons for the development of sustainable microgrid(mG)*** typical power-electronized power systems,mGs make extensive use of power electronics converters,which are highly controllable and flexible but lead to a profound impact on the dynamic performance of the whole *** with traditional large-capacity power systems,mGs are less resistant to perturbations,and various dynamic variables are coupled with each other on multiple timescales,resulting in a more complex system instability *** meet the technical and economic challenges,such as active and reactive power-sharing,voltage,and frequency deviations,and imbalances between power supply and demand,the concept of hierarchical control has been introduced into mGs,allowing systems to control and manage the high capacity of renewable energy sources and ***,as the capacity and scale of the mG system increase,along with a multi-timescale control loop design,the multi-timescale interactions in the system may become more significant,posing a serious threat to its safe and stable *** investigate the multi-timescale behaviors and instability mechanisms under dynamic inter-actions for AC mGs,existing coordinated control strategies are discussed,and the dynamic stability of the system is defined and classified in this ***,the modeling and assessment methods for the stability analysis of multi-timescale systems are also ***,an outlook and discussion of future research directions for AC mGs are also presented.

关键词： sustainable microgrid hierarchical control modeling model simplification multi-timescale dynamic stability analysis timescale decomposition.

New Antenna Array Beamforming Techniques Based on Hybrid Convolution/Genetic Algorithm for 5G and Beyond Communications

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Computer modeling in Engineering & sciences 2024年第3期138卷 2749-2767页

作者： shimaa m.Amer Ashraf A.m.Khalaf amr H.Hussein salman A.Alqahtani mostafa H.Dahshan Hossam m.Kassem Electronics and Communications Engineering Department Higher Institute of Engineering and TechnologyKafr ElsheikhEgypt Electronics and Electrical Communications Engineering Department Faculty of EngineeringMinia UniversityMiniaEgypt Electronics and Electrical Communications Engineering Department Faculty of EngineeringTanta UniversityTantaEgypt Electronics and Electrical Communications Engineering Department Faculty of EngineeringHorus University EgyptNew DamiettaEgypt Department of Computer Engineering College of computer and Information SciencesKing Saud UniversityRiyadh11543Saudi Arabia school of Computing Mathematics and EngineeringCharles Sturt UniversityBathurstNSW2795Australia

side lobe level reduction(sLL)of antenna arrays significantly enhances the signal-to-interference ratio and improves the quality of service(QOs)in recent and future wireless communication systems starting from 5G up to ***,it improves the array gain and directivity,increasing the detection range and angular resolution of radar *** study proposes two highly efficient sLL reduction *** techniques are based on the hybridization between either the single convolution or the double convolution algorithms and the genetic algorithm(GA)to develop the Conv/GA andDConv/GA,*** convolution process determines the element’s excitations while the GA optimizes the element *** m elements linear antenna array(LAA),the convolution of the excitation coefficients vector by itself provides a new vector of excitations of length N=(2m−1).This new vector is divided into three different sets of excitations including the odd excitations,even excitations,and middle excitations of lengths m,m−1,andm,*** the same element spacing as the original LAA is used,it is noticed that the odd and even excitations provide a much lower sLL than that of the LAA but with amuch wider half-power beamwidth(HPBW).While the middle excitations give the same HPBWas the original LAA with a relatively higher *** the increased HPBWof the odd and even excitations,the element spacing is optimized using the ***,the synthesized arrays have the same HPBW as the original LAA with a two-fold reduction in the ***,for extreme sLL reduction,the DConv/GA is *** this technique,the same procedure of the aforementioned Conv/GA technique is performed on the resultant even and odd excitation *** provides a relatively wider HPBWthan the original LAA with about quad-fold reduction in the sLL.

关键词： Array synthesis convolution process genetic algorithm(GA) half power beamwidth(HPBW) linear antenna array(LAA) side lobe level(sLL) quality of service(QOs)

Engineering of efficient visible light photocatalysts:Ti_(1-x+y)Cu_(x)La_(y)O_(2)(x=0.03;y=0,0.005,0.01) compositions

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Journal of Rare Earths 2024年第3期42卷 497-505,I0003页

作者： s.m.Yakout A.m.Youssef Inorganic Chemistry Department National Research Centre(NRC)El Buhouth StDokkiCairo12622Egypt

In dye-photocatalysis, widening the wavelengths absorption range of catalysts as well as aborting the recombination of the photoexcited charge carriers(electrons-holes pairs) are of paramount *** the current study, we report the photocatalytic characteristics of four compositions composed of TiO_(2),Ti_(0.97)Cu_(0.03)O_(2), Ti_(0.965)Cu_(0.03)La_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)powders for two harmful dyes(Congo red and methylene blue). The X-ray diffraction technique verified the configuration of mixed anatase and rutile phases in pure TiO_(2)and Ti_(0.97)Cu_(0.03)O_(2)powders while Ti_(0.965)Cu_(0.03)La_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)powders possess anatase phase only. The changes of the band gap structure and dimensions of the unit cell volume of TiO_(2)confirm the substitution of Ti^(4+)sites by Cu^(2+)and La^(3+)ions. Remarkable widening of wavelengths absorption with formation of long absorption tails were found in TiO_(2)(3.13 e V) through insertion of La^(3+)plus Cu^(2+)ions. Ti_(0.965)Cu_(0.03)La_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)samples exhibit a visible light band gap of 2.3 and 2.7 e V, respectively. Based on sEm images, incorporation of Cu^(2+)and La^(3+)ions influences the surface morphology of TiO_(2). The resulting Ti_(0.97)Cu_(0.03)O_(2), Ti_(0.965)Cu_(0.03)La_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)powders present enhanced photocatalytic activity towards Congo red dye degradation compared to pure one under natural solar spectrum. The best Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)catalyst exhibits superior photocatalytic activity of 96% for 10 ppm CR dye in 20 min as well as above average photocatalytic efficiency of 63% for 30 ppm CR dye in 120 min. As well, it showed acceptable photodegradation activity of 52% for 30 ppm mB solution in 140 min of sunlight irradiation. The heightened photodegradation efficiency of Ti_(0.96)Cu_(0.03)La_(0.01)O_(2)catalyst can be clarified in terms of higher ch

关键词： semiconductor TiO_(2) Rare earths Congo red methylene blue solar spectrum Photodegradation