Browsing by Author "Gunal O."

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    COVID-19: vaccination vs. hospitalization
    (Springer Science and Business Media Deutschland GmbH, 2022) Uzun O.; Akpolat T.; Varol A.; Turan S.; Bektas S.G.; Cetinkaya P.D.; Dursun M.; Bakan N.; Ketencioglu B.B.; Bayrak M.; Baris S.A.; Guner R.; Gunal O.; Nural S.; Deniz P.P.; Toprak O.B.; Ozkan G.; Gumus A.; Kerget F.; Ercelik M.; Ataoglu O.; Yuksel A.; Ates G.; Kutsoylu O.E.; Kose N.; Kizilirmak D.; Keskin S.; Gultekin O.; Coskun N.; Yilmaz E.S.; Uslu S.; Basyigit İ.; Ergan B.; Deveci F.; Yakar M.N.; Zuhur C.; Sagcan G.; Yuce Z.T.; Kuluozturk M.; Sezgin M.E.; Sezgin E.N.A.; Havlucu Y.; Cuhadaroglu C.; Kilinc O.; Boyaci H.; Altunay H.; Akti M.; Dursun Z.B.; Kalem A.K.; Isik S.A.; Akyildiz L.; Aykac N.; Almaz M.S.; Kokturk N.; Itil O.
    Objective: Vaccination is the most efficient way to control the coronavirus disease 2019 (COVID-19) pandemic, but vaccination rates remain below the target level in most countries. This multicenter study aimed to evaluate the vaccination status of hospitalized patients and compare two different booster vaccine protocols. Setting: Inoculation in Turkey began in mid-January 2021. Sinovac was the only available vaccine until April 2021, when BioNTech was added. At the beginning of July 2021, the government offered a third booster dose to healthcare workers and people aged > 50 years who had received the two doses of Sinovac. Of the participants who received a booster, most chose BioNTech as the third dose. Methods: We collected data from 25 hospitals in 16 cities. Patients hospitalized between August 1 and 10, 2021, were included and categorized into eight groups according to their vaccination status. Results: We identified 1401 patients, of which 529 (37.7%) were admitted to intensive care units. Nearly half (47.8%) of the patients were not vaccinated, and those with two doses of Sinovac formed the second largest group (32.9%). Hospitalizations were lower in the group which received 2 doses of Sinovac and a booster dose of BioNTech than in the group which received 3 doses of Sinovac. Conclusion: Effective vaccinations decreased COVID-19-related hospitalizations. The efficacy after two doses of Sinovac may decrease over time; however, it may be enhanced by adding a booster dose. Moreover, unvaccinated patients may be persuaded to undergo vaccination. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.
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    Optimization of Laminar Boundary Layers in Flow over a Flat Plate Using Recent Metaheuristic Algorithms
    (MDPI, 2022) Gunal O.; Akpinar M.; Ovaz Akpinar K.
    Heat transfer is one of the most fundamental engineering subjects and is found in every moment of life. Heat transfer problems, such as heating and cooling, where the transfer of heat between regions is calculated, are problems that can give exact solutions with parametric equations, many of which were obtained by solving differential equations in the past. Today, the fact that heat transfer problems have a more complex structure has led to the emergence of multivariate models, and problems that are very difficult to solve with differential equations have emerged. Optimization techniques, which are also the subject of computer science, are frequently used to solve complex problems. In this study, laminar thermal boundary layers in flow over a flat plate, a sub-problem of heat transfer, is solved with recent metaheuristic algorithms. Teaching learning-based optimization (TLBO), sine cosine optimization (SCO), gray wolf optimization (GWO), whale optimization (WO), salp swarm optimization (SSO), and Harris hawk optimization (HHO) algorithms are used in the study. In the optimization problem, the laminar boundary layer thickness, heat flow, and distance from the leading edge are determined. These three models’ minimum, maximum, and target values are found under the specified design variables and constraints. In the study, 540 optimization models are run, and it is seen that HHO is the most suitable optimization technique for heat transfer problems. Additionally, SSO and WO algorithms gave results close to HHO. Other algorithms also set model targets with an average of less than 0.07% and acceptable error rates. In addition, the average problem solution time of all optimization algorithms and all models was 0.9 s. To conclude, the recent metaheuristic algorithms are found to be powerful and fast in solving heat transfer problems. © 2022 by the authors.
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    Determination of Insulation Parameters with Optimization Algorithms
    (Institute of Electrical and Electronics Engineers Inc., 2022) Gunal O.; Akpinar M.; Akpinar K.O.
    Insulation is one of the essential energy efficiency and sustainability topics. While insulation is primarily the subject of buildings, insulation can also be made in pipes and heat exchangers in the factory environment. In the first example of this study, the insulation material that should be used for the specified heat loss in the case of a basic circular heat source being covered with insulation material was determined, while in the second case, the targeted insulation thickness with the accepted maximum heat loss and insulation material coefficient was tried to be determined. The results obtained show that errors were zero in particle swarm optimization (PSO) and artificial bee colony (ABC) algorithms in the first case. In the second case, PSO, ABC, and firefly (FA) optimization algorithms have the lowest average error with 3x10-5%, 1x10-5%, 3x10-5%, respectively. © 2022 IEEE.
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    Performance Evaluation of Metaheuristic Optimization Techniques in Insulation Problem
    (Institute of Electrical and Electronics Engineers Inc., 2022) Gunal O.; Akpinar M.; Akpinar K.O.
    Selection of insulation material and determination of its thickness are the two most important parameters that prevent heat loss. Too much thickness complicates the price and use. The low coefficient of thermal conductivity of the insulation material reduces heat loss and increases the cost. One of the most important factors when determining the material thickness and conductivity coefficient is the price. In this study, two cases were examined under certain conditions, independent of the price. In the first case, the insulation material is determined, whereas the material thickness is determined in the second case. Six different current metaheuristic algorithms were used to calculate the two cases. It has been observed that harris hawks optimization (HHO), salp swarm optimization (SSO), and whale optimization (WO) algorithms determine the global optimum point without any error in determining the targets of the problem while the processing times were short. Overall, it has been seen that all six algorithms can create solutions to heat transfer problems with very low errors. © 2022 IEEE.