Browsing by Author "Onal O."
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Item Microstructure - Macro property model proposal(2011) Ozturk A.U.; Onal O.; Baradan B.A relationship between the microstructure formation and compressive strength of cement mortars has been established within this study. Microstructure properties such as pore area ratio, total pore length, total dendrite length and average roundness of pore phases were determined by microstructural investigations. In addition, the hydrated part area, calcium hydroxide phase area and unhydrated part area ratios were calculated based on image analysis. Six parameters (pore area ratio, total pore length, total dendrite length, average roundness, hydrated part area ratio and unhydrated part area ratio) were correlated to the compressive strength values of different mixtures. Multiple linear regression investigations indicated that determination of only two parameters (total dendrite length and hydrated part area ratio) is sufficient enough to represent the relationship of microstructural formation-compressive strength confidently. This analysis indicates that the connected channel system of pore phase is more effective on strength than the amount of pore phase. © 2011 Thomas Telford Ltd.Item Effects of micro pore characteristics on strength of cement mortar using artificial neural network(Nova Science Publishers, Inc., 2011) Ozturk A.U.; Onal O.Cementitious materials comprise a great part in construction process of structures such as buildings, bridges, roads and dams. The most expected properties of structural members prepared with cement mortar or concrete, are strength and durability. These structural members are supposed to have strength values determined in the structural analysis and to be durable against aggressive media in their service life. These characteristics are the most effective criteria in civil and material engineering. Therefore, these two parameters depend mainly on the pore structure and its characteristics of structural members. Nowadays, scientists and engineers are using new computer technologies, simulations and experimental techniques try to perform to characterize the inner structure of structural materials in order to define microstructural formations and the effects of microstructural phases such as pores on macro properties. New image capturing tools and their improved magnification capacity induced researchers to have an expanded view on investigation of microstructures. In addition, the results of these studies are simply not enough to realize the simulation of effects of inner structure. Some numerical and statistical methods performed by computers are needed at this stage. Artificial neural network (ANN) is one of these methods. In last decades, artificial neural network applications have become more considerable issue in engineering applications. In the scope of this chapter, pore area ratio values represent total pore area amount in a polished section of cement mortars were determined. Also, some pore characteristics representing the probability of channels between pores are investigated. The pore amounts and these pore characteristics are related to compressive strength values of cement mortars in order to establish a microstructure - macro property relationship. Thus, nondestructive methodologies and artificial neural network have been used in the prediction of a macro property, which only be determined by destructive testing techniques. © 2011 by Nova Science Publishers, Inc. All rights reserved.Item Identification of water/cement ratio of cement pastes, basing on the microstructure image analysis data and using artificial neural network(2013) Ozturk A.U.; Onal O.Artificial Neural Network (ANN) analysis has been established to forecast the Water/Cement (w/c) ratio values of cement pastes by using image analysis techniques in the scope of this study. W/c ratio values have reasonably great effects on the performance of cement based structural members. The service life or ultimate performances such as strength and durability characteristics are strongly affected by w/c ratios of cementitious materials. In this study, the relationship between microstructural phases such as unhydrated cement part, hydration products, capillary porosity, and w/c ratios predicted by ANN analysis, has been established. The predicted values are compared with estimated values obtained by proposed method in the literature. The study indicated that, using a contemporary data analysis technique, which is capable of searching nonlinear relationships more thoroughly, would result in more realistic prediction of the w/c ratios compared to the proposed method. © 2013 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg.Item Push and Pull Factors of Why Medical Students Want to Leave Türkiye: A Countrywide Multicenter Study(Routledge, 2024) Eser E.; Cil E.; Sen Gundogan N.E.; Col M.; Yildirim Ozturk E.N.; Thomas D.T.; Sunter A.T.; Arslan H.N.; Citil R.; Onder Y.; Picakciefe M.; Dede B.; Demirel C.; Aydin N.; Caglayan C.; Aker A.A.; Borlu A.; Durmus H.; Can G.; Siddikoglu E.; Sumer E.H.; Uygun T.; Alkoy S.; Aktas Aycan K.; Koruk İ.; Kuzan R.; Demir L.S.; Hacilar E.; Sari H.; Kilinc Z.; Onal O.; Dogan E.; Emek M.; Terzioglu R.; Yapici G.; Erdal D.; Eser S.; Ayhan Akman E.; Kosan Z.; Yilmaz S.; Ayoglu F.N.; Acikgoz B.; Musal B.; Suner A.F.; Erdogan A.; Cilburunoglu İ.; Saygun M.; Daymaz D.; Arslantas D.; Onsuz M.F.; Beyhun N.E.; Ustundag M.G.; Ekuklu G.; Ozder Tas F.; Abacigil F.; Oncu S.; Hıdıroğlu S.; Ozaydin A.N.; Pirincci E.; Bulut I.; Tozun M.; Eskiocak M.; Gunel P.; Torun S.D.; Yavuz M.; Hasde M.; Camur D.; Gunes G.; Kurt B.; Guler Baysoy N.; Bakirci N.; Demir F.; Catak B.; Ozyurda F.; Turan M.Phenomenon: Physician immigration from other countries is increasing as developed countries continue to be desirable destinations for physicians; however, the determinants of Turkish physicians’ migration decisions are still unclear. Despite its wide coverage in the media and among physicians in Türkiye, and being the subject of much debate, there is insufficient data to justify this attention. With this study, we aimed to investigate the tendency of senior medical students in Türkiye to pursue their professional careers abroad and its related factors. Approach: This cross-sectional study involved 9881 senior medical students from 39 different medical schools in Türkiye in 2022. Besides participants’ migration decision, we evaluated the push and pull factors related to working, social environment and lifestyle in Türkiye and abroad, medical school education inadequacy, and personal insufficiencies, as well as the socioeconomic variables that may affect the decision to migrate abroad. The analyses were carried out with a participation rate of at least 50%. Findings: Of the medical students, 70.7% had emigration intentions. Approximately 60% of those want to stay abroad permanently, and 61.5% of them took initiatives such as learning a foreign language abroad (54.5%) and taking relevant exams (18.9%). Those who wanted to work in the field of Research & Development were 1.37 (95% CI: 1.22–1.54) times more likely to emigrate. The push factor that was related to emigration intention was the “working conditions in the country” (OR: 1.89, 95% CI: 1.56–2.28) whereas the “social environment/lifestyle abroad” was the mere pull factor for the tendency of emigration (OR: 1.73, 95% CI: 1.45–2.06). In addition, the quality problem in medical schools also had a significant impact on students’ decisions (OR: 2.20, 95% CI: 1.83–2.65). Insights: Although the percentage of those who want to emigrate “definitely” was at the same level as in the other developing countries, the tendency to migrate “permanently” was higher in Türkiye. Improving working conditions in the country and increasing the quality of medical faculties seem vital in preventing the migration of physicians. © 2023 Taylor & Francis Group, LLC.