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Improved Approaches Toward Analysis of Electromagnetic Processes in Electrodynamical Devices Based on the Theory of Electromagnetic Field

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Chinese Journal of Electrical Engineering 2023年第4期9卷 88-106页

作者： Yaroslav Kovivchak Department of Automated Control Systems Lviv Polytechnic National UniversityLviv 79013Ukraine

In the course of designing and developing different-purpose electrodynamical devices,electromagnetic processes in movable and immovable media need to be calculated simultaneously.The solution for such tasks based on the electromagnetic field theory is associated with the emergence of significant theoretical and practical difficulties.The problems that arise during the calculation of electromagnetic processes in movable and immovable media of electrodynamical devices using the electromagnetic field theory are examined in this study.Improved approaches toward the calculation of electromagnetic processes in electrodynamical devices using Maxwell’s equations are suggested.Notably,calculating electromagnetic processes in movable and immovable media using Maxwell’s equations necessitates consideration of the systems of coordinates where the electromagnetic phenomena are analyzed.Theoretically substantiated methods of calculating electromagnetic processes in movable and immovable media based on the principles of electromagnetic field theory are proposed.The methods consider the systems of coordinates where the analysis of electromagnetic phenomena is conducted.The effectiveness of the suggested methods for example in calculating electromagnetic processes in movable and immovable media of the turbogenerator is illustrated.

关键词： Theory of electromagnetic field movable and immovable media systems of coordinates mathematical modelling electrodynamical

Optimal COVID-19 epidemic strategy with vaccination control and infection prevention measures in Thailand

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Infectious Disease modelling 2022年第4期7卷 835-855页

作者： Adison Thongtha Chairat Modnak Department of Mathematics Faculty of ScienceNaresuan UniversityPhitsanulok65000Thailand

COVID-19 is a severe acute respiratory syndrome caused by the Coronavirus-2 virus(SARS-CoV-2).The virus spreads from one to another through droplets from an infected person,and sometimes these droplets can contaminate surfaces that may be another infection pathway.In this study,we developed a COVID-19 model based on data and observations in Thailand.The country has strictly distributed masks,vaccination,and social distancing measures to control the disease.Hence,we have classified the susceptible individuals into two classes:one who follows the measures and another who does not take the control guidelines seriously.We conduct epidemic and endemic analyses and represent the threshold dynamics characterized by the basic reproduction number.We have examined the parameter values used in our model using the mean general interval(GI).From the calculation,the value is 5.5 days which is the optimal value of the COVID-19 model.Besides,we have formulated an optimal control problem to seek guidelines maintaining the spread of COVID-19.Our simulations suggest that high-risk groups with no precaution to prevent the disease(maybe due to lack of budgets or equipment)are crucial to getting vaccinated to reduce the number of infections.The results also indicate that preventive measures are the keys to controlling the disease.

关键词： COVID-19 epidemics mathematical modelling Stability analysis Global stability Optimal control problem Infectious disease

Seroprevalence and infection attack rate of COVID-19 in Indian cities

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Infectious Disease modelling 2022年第2期7卷 25-32页

作者： Yiming Fei Hainan Xu Xingyue Zhang Salihu S.Musa Shi Zhao Daihai He Department of Math and Stats The Hang Seng UniversityHong KongChina Department of Math and Stats McMaster UniversityCanada Department of Applied Mathematics The Hong Kong Polytechnic UniversityHong KongChina Department of Mathematics Kano University of Science and TechnologyWudilNigeria JC School of Public Health and Primary Care Chinese University of Hong KongHong KongChina CUHK Shenzhen Research Institute ShenzhenChina

Objectives:Serological surveys were used to infer the infection attack rate in different populations.The sensitivity of the testing assay,Abbott,drops fast over time since infection which makes the serological data difficult to interpret.In this work,we aim to solve this issue.Methods:We collect longitudinal serological data of Abbott to construct a sensitive decay function.We use the reported COVID-19 deaths to infer the infections,and use the decay function to simulate the seroprevalence and match to the reported seroprevalence in 12 Indian cities.Results:Our model simulated seroprevalence matchs the reported seroprevalence in most of the 12 Indian cities.We obtain reasonable infection attack rate and infection fatality rate for most of the 12 Indian cities.Conclusions:Using both reported COVID-19 deaths data and serological survey data,we infer the infection attack rate and infection fatality rate with increased confidence.

关键词： COVID-19 Pandemic Seroprevalence Attack rate mathematical modelling

Meteorological indicators of dengue epidemics in non-endemic Northwest Argentina

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Infectious Disease modelling 2022年第4期7卷 823-834页

作者： Javier Armando Gutierrez Karina Laneri Juan Pablo Aparicio Gustavo Javier Sibona Departamento de Física-FCE-Universidad Nacional de Salta SaltaArgentina Grupo de Física Estadística e Interdisciplinaria CONICETCentro Atòmico Bariloche-CNEASan Carlos de BarilocheRío NegroArgentina Instituto de Investigaciones en Energía no Convencional(INENCO)Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET)-Universidad Nacional de Salta Av.Bolivia 51004400SaltaArgentina Simon A.Levin mathematical Computational and Modeling Sciences Center Arizona State UniversityPO Box 871904TempeAZ85287-1904USA IFEG-CONICET and Fa.M.A.F.-Universidad Nacional de Cordoba CordobaArgentina

In the last two decades dengue cases increased significantly throughout the world,giving place to more frequent outbreaks in Latin America.In the non-endemic city of San Ramòn de la Nueva Orán,located in Northwest Argentina,large dengue outbreaks alternate with several years of smaller ones.This pattern,as well as the understanding of the underlying mechanisms,could be essential to design proper strategies to reduce epidemic size.We develop a stochastic model that includes climate variables,social structure,and mobility between a non-endemic city and an endemic area.Climatic variables were input of a mosquito population ecological model,which in turn was coupled to a meta-population,spatially explicit,epidemiological model.Human mobility was included into the model given the high border crossing to the northern country of Bolivia,where dengue transmission is sustained during the whole year.We tested different hypotheses regarding people mobility as well as climate variability by fitting numerical simulations to weekly clinical data reported from 2009 to 2016.After assessing the number of imported cases that triggered the observed outbreaks,our model allows to explain the observed epidemic pattern.We found that the number of vectors per host and the effective reproductive number are proxies for large epidemics.Both proxies are related with climate variability such as rainfall and temperature,opening the possibility to test these meteorological variables for forecast purposes.

关键词： mathematical modelling Dengue Outbreak Mosquitoes population

Understanding the impact of disease and vaccine mechanisms on the importance of optimal vaccine allocation

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Infectious Disease modelling 2023年第2期8卷 539-550页

作者： Isobel R.Abell James M.McCaw Christopher M.Baker School of Mathematics and Statistics The University of MelbourneMelbourneAustralia Melbourne Centre for Data Science The University of MelbourneMelbourneAustralia Centre for Epidemiology and Biostatistics Melbourne School of Population and Global HealthThe University of MelbourneMelbourneAustralia Peter Doherty Institute for Infection and Immunity The Royal Melbourne Hospital and the University of MelbourneMelbourneAustralia Centre of Excellence for Biosecurity Risk Analysis The University of MelbourneMelbourneAustralia

Vaccination is an important epidemic intervention strategy.However,it is generally unclear how the outcomes of different vaccine strategies change depending on population characteristics,vaccine mechanisms and allocation objective.In this paper we develop a conceptual mathematical model to simulate strategies for pre-epidemic vaccination.We extend the SEIR model to incorporate a range of vaccine mechanisms and disease characteristics.We then compare the outcomes of optimal and suboptimal vaccination strategies for three public health objectives(total infections,total symptomatic infections and total deaths)using numerical optimisation.Our comparison shows that the difference in outcomes between vaccinating optimally and suboptimally depends on vaccine mechanisms,disease characteristics,and objective considered.Our modelling finds vaccines that impact transmission produce better outcomes as transmission is reduced for all strategies.For vaccines that impact the likelihood of symptomatic disease or dying due to infection,the improvement in outcome as we decrease these variables is dependent on the strategy implemented.Through a principled model-based process,this work highlights the importance of designing effective vaccine allocation strategies.We conclude that efficient allocation of resources can be just as crucial to the success of a vaccination strategy as the vaccine effectiveness and/or amount of vaccines available.

关键词： mathematical modelling Epidemiology

modelling and Simulation of Hydro-gel Growth Mechanism by Analysis of Experimental Data

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Chinese Journal of Polymer Science 2014年第3期32卷 350-361页

作者： Priyadarshi Majumdar Jyotinagar Bidyasree Niketan H.S.School GET IIT-JEE BE 89SEC:ISalt Lake CityKolkata 700064India

We have experimentally studied the growth process of a water-absorbing polymer commonly known as hydro-gel. We took a number of spherical beads, immersed them in pure water, measured their diameters at regular intervals of time and plotted graphs showing the change in volume with the time of immersion, to analyze their swelling properties. We have formulated a dynamical model on the basis of curve-fitting to our experimental data. Our mathematical modelling is devoted solely towards the explanation of the swelling of spherical hydro-gels and we have interpreted our observations on these basis. And finally evaluating the constants of the process, we have shown that the results obtained from our modelling and numerical simulation exactly match the experimental data. The justification of this new approach lies in its successful application for the complete explanation of our observations through numerical and analytical ways.

关键词： Hydro-gel Experimental growth study mathematical modelling Numerical analysis.

Review on modelling of corrosion under droplet electrolyte for predicting atmospheric corrosion rate

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Journal of Materials Science & Technology 2021年第3期62卷 254-267页

作者： Bangalore Gangadharacharya Koushik Nils Van den Steen Mesﬁn Haile Mamme Yves Van Ingelgem Herman Terryn Vrije Universiteit Brussel Research Group Electrochemical and Surface Engineering(SURF)Pleinlaan 21050 BrusselsBelgium Vrije Universiteit Brussel Eenheid Algemene Chemie(ALGC)Pleinlaan 21050 BrusselsBelgium

Atmospheric corrosion of metals is the most common type of corrosion which has a significant impact on the environment and operational safety in various situations of everyday life.Some of the common examples can be observed in land,water and air transportation systems,electronic circuit boards,urban and offshore infrastructures.The dew drops formed on metal surface due to condensation of atmospheric moisture facilitates corrosion as an electrolyte.The corrosion mechanisms under these droplets are different from classically known bulk electrolyte corrosion.Due to thin and non-uniform geometric thickness of the droplet electrolyte,the atmospheric oxygen requires a shorter diffusion path to reach the metal surface.The corrosion under a droplet is driven by the depletion of oxygen in the center of the droplet compared to the edge,known as differential aeration.In case of a larger droplet,differential aeration leads to preferential cathodic activity at the edge and is controlled by the droplet geometry.Whereas,for a smaller droplet,the oxygen concentration remains uniform and hence cathodic activity is not controlled by droplet geometry.The geometry of condensed droplets varies dynamically with changing environmental parameters,influencing corrosion mechanisms as the droplets evolve in size.In this review,various modelling approaches used to simulate the corrosion under droplet electrolytes are presented.In the efforts of developing a comprehensive model to estimate corrosion rates,it has been noted from this review that the influence of geometric evolution of the droplet due to condensation/evaporation processes on corrosion mechanisms are yet to be modelled.Dynamically varying external factors like environmental temperature,relative humidity,presence of hygroscopic salts and pollutants influence the evolution of droplet electrolyte,making it a complex phenomenon to investigate.Therefore,an overview of available dropwise condensation and evaporation models which describes the formation and the evolution of droplet g

关键词： Atmospheric corrosion Water droplets mathematical modelling Condensation Evaporation

Studying the efficacy of isolation as a control strategy and elimination of tuberculosis in India:A mathematical model

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Infectious Disease modelling 2023年第2期8卷 458-470页

作者： Archana Singh Bhadauria Hom Nath Dhungana Vinay Verma Stephen Woodcock Tapan Rai Department of Mathematics and Statistics Deen Dayal Upadhyaya Gorakhpur UniversityIndia School of mathematical and Physical Sciences University of Technology SydneyAustralia Faculty of mathematical and Statistical Sciences Institute of Natural Sciences and HumanitiesShri Ramswaroop Memorial UniversityUttar PradeshIndia

India has the highest burden of both tuberculosis(TB)and multidrug-resistant TB(MDRTB)based on the WHO Global TB Report 2019.Although the available data suggest that the total TB incidence has declined,the absolute number of new cases is still increasing.The number of reported TB cases in India in 2018 was 2.2 million,which was 1.5 million in 2009.About 47%increment in TB case notification in India within a decade shows a persistent public health problem.India contributes about 22%of the World's TB burden.Indian National Strategic Plan 2017e2025,sets out the government plans to eliminate TB by 2025.However,the milestone seems unrealistic to achieve the TB eradication goal by 2025.We developed a five-dimensional mathematical model to understand the TB dynamics in India and investigate the possibility of the earliest TB eradication time frame.The model stratifies the entire TB class into three different classes as drug-sensitive(DS),MDR,and isolated classes.The effective reproduction number,equilibrium points,and stability analysis of the model were carried out.This model predicts the total estimated cases of DS-TB and MDR-TB from 2018 to 2035 through numerical simulation and suggests that TB may be eliminated by 2035 in India if the treatment success rate could be achieved to 95%,by contact tracing and isolating at least 50%of MDR-TB.

关键词： Multi-drug resistant Drug-sensitive Isolation Reproduction number mathematical modelling

Kinetic Modeling of Light Naphtha Hydroisomerization in an Industrial Universal Oil Products Penex^(TM)Unit

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Energy Engineering 2023年第6期120卷 1371-1386页

作者： Ramzy S.Hamied Zaidoon M.Shakor Anfal H.Sadeiq Adnan A.Abdul Razak Ammar T.Khadim Department of Petroleum Technology University of TechnologyBaghdadIraq Department of Chemical Engineering University of TechnologyBaghdadIraq Midland Refineries Company Al-Dura RefineryBaghdadIraq

Recently,the isomerization of light naphtha has been increasingly significant in assisting refiners in meeting sternness specifications for gasoline.Isomerization process provides refiners with the advantage of reducing sulfur,olefin,and benzene in the gasoline basin without significantly victimizing the octane.The mathematical modeling of a chemical reaction is a critical tool due to it can used to optimize the experimental data to estimate the optimum operating conditions for industrial reactors.This paper describes light naphtha isomerization reactions over a Pt/Al_(2)O_(3)-Cl catalyst at the Al-Dura Oil Refinery(Baghdad,Iraq)using a newly developed universal mathematical model.The proposed kinetic model involves 117 isomerization reactions and 90 cracking reactions to describe 52 real components graded from methane to n-octane.A Genetic Algorithm stochastic optimization technique applied in MATLAB R2020a software was employed to estimate the optimal set of kinetic parameters.The calculated activation energies for hydrocracking reactions was found to be higher than the other reactions because of hydrocracking reactions occur at higher range of temperatures.By benchmarking between the experimental and theoretical results for all 117 data sets,the mean absolute error was obtained to be 0.00360 for all 52 components.Also,a positive effect of increasing reaction temperatures was recognized on enhancing the research octane number(RON).

关键词： Light naphtha hydroisomerization reactions kinetics mathematical modelling