Browsing by Author "Ilhan, Ö"

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    A Numerical Approach Technique for Solving Generalized Delay Integro-Differential Equations with Functional Bounds by Means of Dickson Polynomials
    Kürkçü, OK; Aslan, E; Sezer, M; Ilhan, Ö
    In this study, we have considered the linear classes of differential-(difference), integro-differential-(difference) and integral equations by constituting a generalized form, which contains proportional delay, difference, differentiable difference or delay. To solve the generalized form numerically, we use the efficient matrix technique based on Dickson polynomials with the parameter-a along with the collocation points. We also encode the useful computer program for susceptibility of the technique. The residual error analysis is implemented by using the residual function. The consistency of the technique is analyzed. Also, the numerical results illustrated in tables and figures are compared.
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    Non-Synchronized Nasal Intermittent Positive Pressure Ventilation (NIPPV) Versus Nasal Continuous Positive Airway Pressure (NCPAP) After Extubation in Preterm Infants with Respiratory Distress Syndrome
    Ilhan, Ö; Özdemir, SA; Akbay, S; Kanar, B; Memur, S; Bor, M; Özer, EA
    Objective: To determine whether non-synchronized nasal intermittent positive pressure ventilation (NIPPV) reduces the rates of extubation failure, compared to nasal continuous positive airway pressure (NCPAP), in preterm infants with respiratory distress syndrome (RDS). Method: This retrospective study included a total of 49 premature infants who were born at <32 gestational weeks with a birth weight of <1.500 g and required intubation due to RDS. The patients were followed up with NIPPV or NCPAP after extubation. The primary outcome was extubotion failure within 48 hrs of extubotion, while the secondary outcome was neonatal morbidities. Results: A total of 23 patients received NCPAP and 26 patients NIPPV following extubation. Demographic characteristics were similar in both NCPAP and NIPPV groups. Extubation failure was observed in five (21.7%) NCPAP, and in nine (34.6%) NIPPV patients, although any statistically significant intergroup difference was not detected (p=0.32). There were no significant intergroup differences as for post-extubation atelectasis, pneumothorax. Neonatal morbidities and mortality rates. However, the incidence of patent ductus arteriosus was statistically significantly higher in the NIPPV group (p<0.05). In none of the patients gastric or intestinal perforations were observed. Conclusion: It was concluded that NIPPV is not superior to NCPAP performed in preterm infants after extubation in reducing the incidence of reintubation and respiratory morbidities, including pneumothorax and post-extubation atelectasis.
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    Prediction of Flow Behavior and Deformation Analysis of AA5754 Sheet Metal at Warm and Hot Temperatures
    Sen, N; Civek, T; Ilhan, Ö; Yurt, ÖE; Çetin, MH; Simsir, H
    The utilization of lightweight materials such as AA5754 aluminum alloys in the inner body panel parts of vehicles has been significantly important for automotive manufacturers to minimize the high fuel consumption by reducing the overall weight. In this study, the flow behavior of AA5754 sheet metal has been discussed by conducting uniaxial tensile tests at five different temperatures (RT, 200, 250, 300, 350 degrees C) and three strain rates (0.001, 0.01, 0.05 s(-1)). Additionally, the capability of Fields and Backofen (F&B) and Voce hardening rules in describing the flow behavior of AA5754 at different temperatures and strain rates has been investigated by conducting uniaxial tensile tests in finite element analysis. It has been found that the main deformation mechanisms for the AA5754 are the strain hardening mechanism up to 250 degrees C, strain hardening and dynamic recovery mechanisms at 300 degrees C, dynamic recrystallization and strain hardening mechanisms at 350 degrees C. While the F&B hardening rule has been able to successfully capture the flow behavior of AA5754 up to 250 degrees C with a 14.36% error, its capability has significantly reduced after 250 degrees C due to its incapability of describing the effects of dynamic recovery and recrystallization. Voce hardening model has been better able to describe the flow behavior of AA5754 at all the temperature levels than F&B model due to its saturation behavior.