Akademik Arşiv / Academic Archive
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Publication An Evolutionary Clustering Analysis of Social Media Content and Global Infection Rates During the COVID-19 Pandemic(World Scientific Pub Co Pte Lt, 2021-06-19) Ibrahim Arpaci; Shadi Alshehabi; Ibrahim Mahariq; Ahmet E. TopcuThis study investigates the impact of global infection rates on social media posts during the COVID-19 pandemic. The study analysed over 179 million tweets posted between March 22 and April 13, 2020 and the global COVID-19 infection rates using evolutionary clustering analysis. Results showed six clusters constructed for each term type, including three-level [Formula: see text]-grams (unigrams, bigrams and trigrams). The frequent occurrences of unigrams (“COVID-19”, “virus”, “government”, “people”, etc.), bigrams (“COVID 19”, “COVID-19 cases”, “times share”, etc.) and trigrams (“COVID 19 crisis”, “things help stop” and “trying times share”) were identified. The results demonstrated that the unigram trends on Twitter were up to about two times and 54 times more common than the bigram terms and trigram terms, respectively. Unigrams like “home” or “need” also became important as these terms reflected the main concerns of people during this period. Taken together, the present findings confirm that many tweets were used to broadcast people’s prevalent topics of interest during the COVID-19 pandemic. Furthermore, the results indicate that the number of COVID-19 infections had a significant effect on all clusters, being strong on 86% of clusters and moderate on 16% of clusters. The downward slope in global infection rates reflected the start of the trending of “social distancing” and “stay at home”. These findings suggest that infection rates have had a significant impact on social media posting during the COVID-19 pandemic.Publication Modeling of Heart Rate Variability Using Time-Frequency Representations(Computers, Materials and Continua (Tech Science Press), 2021) Ghaylen Laouini; Ibrahim Mahariq; Thabet Abdeljawad; Hasan Aksoy; Aksoy, HasanPublication Technical Design and Economic Investigations for Reducing CO2 Emission considering Environmental Protection Agency Standards by Employing an Optimum Grid-Connected PV/Battery System(Hindawi Limited, 2022-04-18) Habib Forootan Fard; Morteza Fahim Alavi; Hassan Sharabaty; Milad Ahmadzadeh; Ibrahim Mahariq; Mamdouh El Haj AssadPollutant emission is one of the most important problems the world faces. Using sustainable energies is among the best solutions which can be employed to reduce CO2 and other pollutants as in Environmental Protection Agency (EPA) standards. In this study, a case study region located in the south of Iran, including 100 households, is studied to find practical methods of investment to partially replace the required energy by renewables where the total emission is confined to the EPA standards. The solar irradiant of the region is 5.36 kWh/m2/day which causes high energy consumption (3000 kWh/day). If the government invests $495705, which is equal to the social penalty that has to be paid for emissions in 20 years, a 230 kW PV with a vertical tracker can be implemented to reduce 36% of the total emission that will be produced through the current system. The payback period for the proposed system will be around 11 years. Using an optimized hybrid system instead of a system without any renewables modeled in HOMER software in which the initial capital is limited reduces the cost of energy (COE) and the total net present cost (NPC) by 16% and 11%, respectively. The COE and NPC for the current system without any renewables are 0.121 ($/kWh) and 2.28 M ($), respectively. Although the acceptable Renewable Fraction (RF) is about 55%, using 38.5% RF can significantly fulfill the EPA standards and consider the plan's economic and executional conditions.Publication Numerical Inverse Laplace Transform Methods for Advection-Diffusion Problems(MDPI AG, 2022-12-01) Farman Ali Shah; Wael Hosny Fouad Aly; Hasan Aksoy; Fahad M. Alotaibi; Ibrahim Mahariq; Aksoy, HasanPartial differential equations arising in engineering and other sciences describe nature adequately in terms of symmetry properties. This article develops a numerical method based on the Laplace transform and the numerical inverse Laplace transform for numerical modeling of diffusion problems. This method transforms the time-dependent problem to a corresponding time-independent inhomogeneous problem by employing the Laplace transform. Then a local radial basis functions method is employed to solve the transformed problem in the Laplace domain. The main feature of the local radial basis functions method is the collocation on overlapping sub-domains of influence instead of on the whole domain, which reduces the size of the collocation matrix; hence, the problem of ill-conditioning in global radial basis functions is resolved. The Laplace transform is used in comparison with a finite difference technique to deal with the time derivative and avoid the effect of the time step on numerical stability and accuracy. However, using the Laplace transform sometimes leads to a solution in the Laplace domain that cannot be converted back into the real domain by analytic methods. Therefore, in such a case, the Laplace transform is inverted numerically. In this investigation, two inversion techniques are utilized; (i) the contour integration method, and (ii) the Stehfest method. Three test problems are used to evaluate the proposed numerical method. The numerical results demonstrate that the proposed method is computationally efficient and highly accurate.