ABSTRACT
In this article, the authors introduce a mathematical model of the critical Coronavirus Disease (Covid-19) situation in Thailand during March 2021 to August 2021. The work is divided into three parts. Firstly, the model is formulated with a description of the parameters defined in the model, the we compute the basic reproduction number (R0) and study the locally asymptotically stability of its disease free equilibrium point, the existence of endemic equilibrium point, and locally and globally asymptotically stability of its endemic equilibrium point. Secondly, we present a strategy using fixed point iterative methods for solving a nonlinear dynamical problem in form of Green's function for analysis of the parameters, the existence and convergence theorems of solutions are shown by the fixed point theorem techniques. Finally, the authors show the numerical to predict the future situation of coron-avirus disease in Thailand contain R0 and give the conclusion of this work. © 2022, Thammasat University. All rights reserved.
ABSTRACT
Turkey reported the first case of COVID-19 on 11 March 2020 since the outbreak of the deadly coronavirus pandemic. COVID-19 spread rapidly in Turkey, where about a total of 3,208,173 cases of infected persons were registered by 29 March 2021 with 2,957,093 cases of recovered persons and 31,076 reported deaths. A new mathematical COVID-19 model containing six classes is presented. Also, the positive invariant region of the solutions, basic reproductive number, disease-free equilibrium, and its stability are highlighted. Afterward, the disease-free equilibrium is locally asymptotically stable when R0 < 1. Moreover, the proposed model was further generalized to the fractional-order derivative in the AtanganaBaleanu (ABC) context for a more successful realization. Besides, the existence and uniqueness of solutions via techniques of Schaefer's and Banach fixed point theorems were established. Based on the publicly recorded number of infected people from 1-31 July 2020 in Turkey and least-squares curve fitting techniques with fminsearch function the fractionalorders model has been validated and can better fit the data compared with the integer-order model. Also, using the Atangana-Toufik scheme, numerical solutions, as well as simulations, are presented for different values of fractional order. © 2022, Thammasat University. All rights reserved.
ABSTRACT
A new inclusion called total inclusion relation has improved the existing dissimilarity measure for q-rung orthopair fuzzy sets (qROFSs). For qROFSs, the modified axiomatic definition of dissimilarity measure is proposed. The modified Hamming and Euclidean dissimilarity measures are defined. An algorithmic procedure for a robust VIKOR method based on modified dissimilarity measures is established. The application of the robust VIKOR method in Mass Vaccination Campaigns (MVCs) in the COVID-19 situation is given.
ABSTRACT
The whole world is still shaken by the new corona virus and many countries are starting opting for the lockdown again after the first wave that already killed thousands of people. New observations also show that the virus spreads quickly during the cold period closer to winter season. On the other side, the number of new infections decreases considerably during hot period closer to summer time. The geographic structure of our planet is such that when some countries (in a hemisphere) are in their winter season, others in the other hemisphere are in their summer season. However, we have observed in the world some countries undertaking national lockdown during their summer time, which result in their economy to be hugely hit. Other factors, beside the lockdown, have also impacted negatively the socio-economic situation in affected countries. These include, among others, the human immunodeficiency virus (HIV) susceptible to combine to the new corona virus. The new corona virus is indeed recent and many of its effect and impact on the society are still unknown and are still to be uncovered. Hence we use here the of Atangana-Baleanu fractional derivative to mathematically express and analyses a model of HIV disease combined with COVID-19 to assess the pandemic situation in many countries affected, such as South Africa, United Kingdom (UK), China, Spain, United States of America (USA), and Italy. A way to achieve that is to perform stability and bifurcation analysis. It is also possible to investigate in which conditions the combined model contains a forward and a backward bifurcation. Moreover, utilizing the techniques of Schaefer and Banach fixed point theorems, existence and uniqueness of solutions of the generalized fractional model were presented. Also, the Atangana-Baleanu fractional (generalized) HIV-COVID-19 con-infection model is solved numerically via well-known and effective numerical scheme and a predicted prevalence for the COVID-19 is provided. The global trend shown by the numerical simulation proves that the disease will stabilize at a later stage when adequate measures are taken. © 2021 THE AUTHORS