Research of the impact of material and flow properties on fluid-structure interaction in cage systems

Mehmet Emin Özdemir,Murat Yaylacı 한국풍공학회 2023 Wind and Structures, An International Journal (WAS Vol.36 No.1

This paper investigates the mechanical behavior of full-scale offshore fish cages under hydrodynamic loads. To simulate different cases, different materials were used in the fish cage and analyzed under different flow velocities. The cage system is studied in two parts: net cage and floating collar. Analyses were performed with the ANSYS Workbench program, which allows the Finite Element Method (FEM) and Computational Fluid Dynamics (CFD) method to be used together. Firstly, the fish cage was designed, and adjusted for FSI: Fluid (Fluent) analysis. Secondly, mesh structures were created, and hydrodynamic loads acting on the cage elements were calculated. Finally, the hydrodynamic loads were transferred to the mechanical model and applied as a pressure on the geometry. In this study, the equivalent (von Mises) stress, equivalent strain, and total deformation values of cage elements under hydrodynamic loads were investigated. The data obtained from the analyses were presented as figures and tables. As a result, it has been shown that it is appropriate to use all the materials examined for the net cage and the floating collar.

Can Cochlear Nerve Size Assessment With Magnetic Resonance Enhance the Understanding of Idiopathic Sudden Sensorineural Hearing Loss?

Arslan Hande,Özdemir Meltem,Kavak Rasime Pelin,Keseroğlu Kemal,Mutlu Murad,Korkmaz Mehmet Hakan 대한청각학회 2024 Journal of Audiology & Otology Vol.28 No.1

Background and Objectives: Idiopathic sudden sensorineural hearing loss (ISSHL) is a rapid loss of hearing, exceeding 30 dB in at least 3 consecutive frequencies within 3 days, without any identifiable cause despite thorough investigations. Currently, the etiology and pathogenesis of ISSHL have not been fully elucidated. This study aimed to assess the size of the cochlear nerve in patients with ISSHL and explore its relationship with pretreatment audiograms and treatment response.Subjects and Methods: A total of 125 patients (59 [47.2%] women; mean age 47.7±13.8 years [minimum-maximum: 21-76]) and 60 healthy participants (27 [45%] women; mean age 45.7±16.8 years [minimum-maximum: 20-76]) as a control group were included in this study. The size of the cochlear nerve was assessed on the affected side, compared to the control group, as well as on the unaffected side. Pretreatment and posttreatment audiological values were also analyzed.Results: The cross-sectional area (CSA), vertical diameter (VD), and horizontal diameter (HD) of the CN were found to be smaller on the affected side of ISSHL patients compared to the control group (p<0.01; p=0.04; p=0.02, respectively). In the study group (affected side of ISSHL patients), there were no significant differences in VD, HD, and CSA values between pretreatment audiogram types (p=0.23; p=0.53; p=0.39, respectively), and initial hearing levels (p=0.16; p=0.22; p=0.23, respectively). Furthermore, there were no significant differences in VD, HD, and CSA values between the recovery groups according to Furuhashi criteria (p=0.18; p=0.37; p=0.27, respectively).Conclusions: The size of the CN may be a risk factor for ISSHL, but it does not affect the type of audiogram curves and was not prognostic in terms of treatment response.

Determination of Thermal Conductivities of Solid and Liquid Phases for Rich-Sn Compositions of Sn-Mg Alloy

Fatma Meydaneri,Mehmet Gündüz,Mehmet Özdemir,Buket Saatçi 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.1

The variations of thermal conductivities of solid phases versus temperature for pure Sn and Sn-1 wt% Mg,Sn-2 wt% Mg, and Sn-6 wt% Mg binary alloys were measured with a radial heat flow apparatus. Thermal conductivity variations versus temperature for pure Sn and Sn-1 wt% Mg, Sn-2 wt% Mg, and Sn-6 wt% Mg binary alloys were found to be 60.60 ± 3.63, 61.99 ± 3.71, 68.29 ± 4.09, and 82.04 ± 4.92 W/Km, respectively. The thermal conductivity ratios of liquid phase to solid phase for pure Sn and eutectic Sn-2 wt% Mg alloy at their melting temperature were found to be 1.11 and 1.08, respectively, with a Bridgman type directional solidification apparatus. Thus the thermal conductivities of liquid phases for pure Sn and eutectic Sn-2 wt%Mg binary alloy at their melting temperature were evaluated to be 67.26 ± 4.03 and 73.75 ± 4.42 W/Km,respectively, by using the values of solid phase thermal conductivities and the thermal conductivity ratios of the liquid phase to the solid phase.

Incidental gallbladder cancer: a retrospective clinical study of 40 cases

Merih Altiok,Hanife Gülnihal Özdemir,Feyzi Kurt,Mehmet Onur Gul,Serdar Gumus 대한외과학회 2022 Annals of Surgical Treatment and Research(ASRT) Vol.102 No.4

Purpose: Cholecystectomy is one of the most common surgeries today due to gallbladder diseases. The most prevalent malignancy of the biliary tract is gallbladder cancer. We aimed to discuss the results of our patients who underwent cholecystectomy for benign reasons in our clinic and who had gallbladder cancer due to pathology. Methods: The results of cholecystectomy performed in General Surgery Clinic of Seyhan Government Hospital were evaluated. Cases diagnosed as gallbladder as a result of histopathological examination were included. Preoperative ultrasonography, laboratory findings, and postoperative pathology results of the patients were reviewed retrospectively. The pathologist repeated histopathological evaluations. Results: Between 2010 and 2019, incidental gallbladder cancer (IGBC) was detected in 40 patients (0.3%) in 11,680 cholecystectomy operations. Of the patients diagnosed with IGBC, 14 (35.0%) were T1a, 11 (27.5%) were T1b, 11 (27.5%) were T2, and 4 (10.0%) were T3. T4 tumor was not seen in any patient. Three patients who were T1b at initial evaluation were identified as T2 at evaluation for the study. The pathology results of 37 patients (92.5%) were adenocarcinoma, 2 (5.0%) were adenosquamous type, and 1 (0.5%) was squamous cell carcinoma. Conclusion: There has been a remarkable increase in the number of IGBCs over the past 20 years. Appropriate staging and histopathological evaluation are essential in guiding the surgeon’s operation. It is crucial to accurately determine the T stage, the most influential parameter on patient survival and residual recurrences. The distinction between pathologic (p) T1a and pT1b should be made carefully. Surgery is the only potentially curative method.

Experimental Determination of Interfacial Energy for Solid Zn Solution in the Sn-Zn Eutectic System

Fatma Meydaneri,Mehtap Payveren,Buket Saatçi,Mehmet Özdemir,Necmettin Marasli 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.1

The grain boundary groove shapes for Zn solid solution in equilibrium with Sn-Zn eutectic liquid were observed with a radial heat flow apparatus. From the observed grain boundary groove shapes, the Gibbs-Thomson coefficient, the solid-liquid and the grain boundary energy for the Zn solid solution in equilibrium with Sn-Zn eutectic liquid were determined to be (2.32 ± 0.13)×10−8Km, (120.87 ± 13.29)×10−3J.m−2and (194.76± 23.37)×10−3J.m−2, respectively. The termal conductivity of the eutectic Sn- 9 wt% Zn solid solution, κS,was obtained as 74.74 W/Km by using a radial heat flow apparatus. The thermal conductivity ratio of the eutectic liquid to the eutectic solid, R = κL/κS was found to be 0.58 with a Bridgman-type directional growth apparatus. Thus, the value of the thermal conductivity of eutectic Sn- 9 wt% Zn liquid solution, κL, was obtained as 43.82 W/Km.

Endocan and Non-Dipping Circadian Pattern in Newly Diagnosed Essential Hypertension

Tolga Çimen,Murat Bilgin,Ahmet Akyel,Mehmet Ali Felekoğlu,Ali Nallbani,Şeyda Özdemir,Gönül Erden,Alpaslan Öztürk,Mehmet Doğan,Ekrem Yeter 대한심장학회 2016 Korean Circulation Journal Vol.46 No.6

Background and Objectives: Non-dipper hypertension is frequently accompanied by endothelial dysfunction and activation. Previous studies suggested that endocan may be a novel endothelial dysfunction marker. This study aims to investigate the association between circadian blood pressure (BP) pattern and plasma endocan levels together with high-sensitivity C-reactive protein (hsCRP) in patients with newly diagnosed untreated hypertension. Subjects and Methods: Twenty-four hour ambulatory blood pressure monitoring was recorded in 35 dipper, 35 non-dipper hypertensives and 35 healthy controls. Endocan levels were measured by enzyme-linked immunosorbent assay. Serum levels of hsCRP were also recorded. Results: Despite similar daytime and 24-hour average BP values between dippers and non-dippers, statistically significant high nocturnal BP was accompanied by a non-dipping pattern (Systolic BP: 132±9 vs. 147±11 mmHg; Distolic BP: 80±7 vs. 91±9 mmHg, respectively, p<0.001 for both). Non-dipper patients demonstrated higher endocan levels compared to dippers and normotensives (367 (193-844) pg/mL, 254 (182-512) pg/mL and 237 (141-314) pg/ml, respectively, p<0.001). HsCRP levels were significantly higher in non-dippers than the other groups (p=0.013). In a multivariate logistic regression analysis, endocan (p=0.021) and hsCRP (p=0.044) were independently associated with a non-dipping pattern. Conclusion: Elevated endocan levels were found in non-dipper groups. Endocan and hsCRP were found to be independently associated with a non-dipping pattern. We suggest that elevated levels of endocan in non-dipper hypertensive patients might be associated with a longer duration of exposure to high BP. These results point to the possible future role of endocan in selection of hypertensive patients at higher risk or target organ damage

Application of artificial neural networks in the analysis of the continuous contact problem

Ecren Uzun Yaylacı,Erdal Öner,Murat Yaylacı,Mehmet Emin Özdemir,Ahmad Abushattal,Ahmet Birinci 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.1

This paper investigates the artificial neural network (ANN) to predict the dimensionless parameters for contact pressures and contact lengths under the rigid punch, the initial separation loads, and the initial separation distances of a contact problem. The problem consisted of two elastic infinitely layers (EL) loaded by means of a rigid cylindrical punch and resting on a half-infinite plane (HP). Firstly, the problem was formulated and solved theoretically using the Theory of Elasticity (ET). Secondly, the contact problem was extended based on the ANN. External load, the radius of punch, layer heights, and material properties were created by giving examples of different values used at the training and test stages of ANN. Finally, the accuracy of the trained neural networks for the case was tested using 134 new data, generated via ET solutions to determine the best network model. ANN results were compared with ET results, and well agreements were achieved.

Vibration and buckling analyses of FGM beam with edge crack: Finite element and multilayer perceptron methods

Murat Yaylacı,Ecren Uzun Yaylacı,Mehmet Emin Özdemir,Şevval Öztürk,Hasan Sesli 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.4

This study represents a numerical research in vibration and buckling of functionally graded material (FGM) beam comprising edge crack by using finite element method (FEM) and multilayer perceptron (MLP). It is assumed that the material properties change only according to the exponential distributions along the beam thickness. FEM and MLP solutions of the natural frequencies and critical buckling load are obtained of the cracked FGM beam for clamped–free (C-F), hinged–hinged (H-H), and clamped–clamped (C-C) boundary conditions. Numerical results are obtained to show the effects of crack location (c/L), material properties (E2/E1), slenderness ratio (L/h) and end supports on the bending vibration and buckling properties of cracked FGM beam. The FEM analysis used in this paper was verified with the literature, and the fundamental frequency ratio ( ̅) and critical buckling load ratio ( ̅̅̅̅) results obtained were compared with FEM and MLP. The results obtained are quite compatible with each other

Solving the contact problem of functionally graded layers resting on a HP and pressed with a uniformly distributed load by analytical and numerical methods

Murat Yaylacı,Bahar Şengül Şabano,Mehmet Emin Özdemir,Ahmet Birinci 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.82 No.3

The aim of this study is to examine the frictionless double receding contact problem for two functionally graded (FG) layers pressed with a uniformly distributed load and resting on a homogeneous half plane (HP) using analytical and numerical methods. The FG layers are made of a non-homogeneous material with an isotropic stress-strain law with exponentially varying properties. It is assumed that the contact at the FG layers and FG layer-HP interface is frictionless. The body force of the FG layers and homogeneous HP are ignored in the study. Firstly, an analytical solution for the contact problem has been realized using the theory of elasticity and the Fourier integral transform techniques. Then, the problem modeled and two-dimensional analysis was carried out by using the ANSYS package program based on FEM. Numerical results for contact lengths and contact pressures between FG layers and FG layer-HP were provided for various dimensionless quantities including material inhomogeneity, distributed load width, the shear module ratio, and the heights of the FG layers for both methods. The results obtained using FEM were compared with the results found using the analytical formulation. It was found that the results obtained from analytical formulation were in perfect agreement with the FEM study.

Implementation of finite element and artificial neural network methods to analyze the contact problem of a functionally graded layer containing crack

Murat Yaylacı,Ecren Uzun Yaylacı,Mehmet Emin Özdemir,Sevil Ay,Şevval Öztürk 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.4

In this study, a two-dimensional model of the contact problem has been examined using the finite element method (FEM) based software ANSYS and based on the multilayer perceptron (MLP), an artificial neural network (ANN). For this purpose, a functionally graded (FG) half-infinite layer (HIL) with a crack pressed by means of two rigid blocks has been solved using FEM. Mass forces and friction are neglected in the solution. Since the problem is analyzed for the plane state, the thickness along the z-axis direction is taken as a unit. To check the accuracy of the contact problem model the results are compared with a study in the literature. In addition, ANSYS and MLP results are compared using Root Mean Square Error (RMSE) and coefficient of determination (R2), and good agreement is found. Numerical solutions are made by considering different values of external load, the width of blocks, crack depth, and material properties. The stresses on the contact surfaces between the blocks and the FG HIL are examined for these values, and the results are presented. Consequently, it is concluded that the considered non-dimensional quantities have a noteworthy influence on the contact stress distributions, and also, FEM and ANN can be efficient alternative methods to time-consuming analytical solutions if used correctly.