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Papers by Gökhan Akyol

Research paper thumbnail of Ultrasound : ICA 2016-741 An ultrasonic waveguide sensor for monitoring alcohol concentration in water-alcohol mixtures

In this study, a sensor system that can measure the alcohol concentration of a mixture composed o... more In this study, a sensor system that can measure the alcohol concentration of a mixture composed of ethanol and water using guided ultrasonic waves is presented. The complexity of the problem arises from the fact that ethanol-water mixtures can constitute acoustic velocities higher than the individual acoustic velocities of water and ethanol. A measured acoustic velocity may correspond to two different compositions, requiring both acoustic velocity and density of the mixture to be measured simultaneously to identify the alcohol concentration of the mixture. The sensor system, utilizing Scholte waves, enables measurements inside a closed container through a waveguide, without the mixture exposed to air. Following a detailed dispersion analysis, Scholte waves are employed using mode conversion from Lamb waves utilizing a piezoelectric transducer attached to a thin wave-guiding plate to measure the acoustic velocity and density of such mixtures.

Research paper thumbnail of Çok Katmalı Yapıların Bozulma Analizi Için Yarı-Analitik Sonlu Eleman Modellenmesi

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2017Includes bibli... more Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2017Includes bibliographical references (leaves: 65-68)Text in English; Abstract: Turkish and EnglishUltrasonic guided waves are frequently employed for Non-destructive tests (NDT), and Structural Health Monitoring (SHM) applications in the industry. Several analytical and numerical approaches have been developed in order to investigate guided wave behavior on multilayered structures. In this thesis, guided waves were investigated using the Semi-Analytical Finite Element (SAFE) approach on planar (plate like) structures. The guided wave theory and dispersive behavior in bounded structure were presented for Lamb waves for isotropic elastic plate model first. The numerical method to solve the SAFE problem was developed using the Matlab 2014b in order to obtain dispersion curves. The curves were compared with the Disperse Software, which utilizes global matrix approach for analytical solution of the same pro...

Research paper thumbnail of Effect of mechanical vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migration

Eye, 2002

vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migr... more vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migration Abstract Purpose To investigate keratocyte apoptosis and polymorphonuclear (PMN) cell infiltration to the corneal stroma after mechanical epithelial scraping and chemical de-epithelialization with 18% ethanol solution. Methods Twelve New Zealand Albino rabbits (24 eyes) were randomly divided into three groups. Group A was the control group with no epithelial removal. Group B underwent a 7.5-mm mechanical epithelial removal with a blunt spatula. Group C underwent 7.5-mm chemical deepithelialization with 18% ethanol-balanced salt solution. Corneas were stained with terminal deoxyribonucleotidyl transferasemediated dUTP-digoxigenin nick-end labeling (TUNEL) assay after 24 h. Only nuclear staining in keratocytes was counted. Polymorphonuclear (PMN) leukocyte densities were also assessed by light microscopy. Results Mechanical de-epithelialization (group B) and chemical de-epithelialization with 18% ethanol (group C) showed no difference in keratocyte apoptosis compared with the control group. There was also no difference between groups B and C. Group B showed no difference in PMN leukocyte counts compared with the control group. But the number of PMN leukocytes observed in group C was significantly higher than those encountered in the corneas of the control group (P Ͻ 0.05) and group B (P Ͻ 0.05). Conclusions Dilute alcohol induces more PMN cell infiltration when compared with mechanical de-epithelialization although there is no difference in the apoptosis rates.

Research paper thumbnail of Effect of mechanical vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migration

Eye, 2002

vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migr... more vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migration Abstract Purpose To investigate keratocyte apoptosis and polymorphonuclear (PMN) cell infiltration to the corneal stroma after mechanical epithelial scraping and chemical de-epithelialization with 18% ethanol solution. Methods Twelve New Zealand Albino rabbits (24 eyes) were randomly divided into three groups. Group A was the control group with no epithelial removal. Group B underwent a 7.5-mm mechanical epithelial removal with a blunt spatula. Group C underwent 7.5-mm chemical deepithelialization with 18% ethanol-balanced salt solution. Corneas were stained with terminal deoxyribonucleotidyl transferasemediated dUTP-digoxigenin nick-end labeling (TUNEL) assay after 24 h. Only nuclear staining in keratocytes was counted. Polymorphonuclear (PMN) leukocyte densities were also assessed by light microscopy. Results Mechanical de-epithelialization (group B) and chemical de-epithelialization with 18% ethanol (group C) showed no difference in keratocyte apoptosis compared with the control group. There was also no difference between groups B and C. Group B showed no difference in PMN leukocyte counts compared with the control group. But the number of PMN leukocytes observed in group C was significantly higher than those encountered in the corneas of the control group (P Ͻ 0.05) and group B (P Ͻ 0.05). Conclusions Dilute alcohol induces more PMN cell infiltration when compared with mechanical de-epithelialization although there is no difference in the apoptosis rates.

Research paper thumbnail of Ultrasound : ICA 2016-741 An ultrasonic waveguide sensor for monitoring alcohol concentration in water-alcohol mixtures

In this study, a sensor system that can measure the alcohol concentration of a mixture composed o... more In this study, a sensor system that can measure the alcohol concentration of a mixture composed of ethanol and water using guided ultrasonic waves is presented. The complexity of the problem arises from the fact that ethanol-water mixtures can constitute acoustic velocities higher than the individual acoustic velocities of water and ethanol. A measured acoustic velocity may correspond to two different compositions, requiring both acoustic velocity and density of the mixture to be measured simultaneously to identify the alcohol concentration of the mixture. The sensor system, utilizing Scholte waves, enables measurements inside a closed container through a waveguide, without the mixture exposed to air. Following a detailed dispersion analysis, Scholte waves are employed using mode conversion from Lamb waves utilizing a piezoelectric transducer attached to a thin wave-guiding plate to measure the acoustic velocity and density of such mixtures.

Research paper thumbnail of Çok Katmalı Yapıların Bozulma Analizi Için Yarı-Analitik Sonlu Eleman Modellenmesi

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2017Includes bibli... more Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2017Includes bibliographical references (leaves: 65-68)Text in English; Abstract: Turkish and EnglishUltrasonic guided waves are frequently employed for Non-destructive tests (NDT), and Structural Health Monitoring (SHM) applications in the industry. Several analytical and numerical approaches have been developed in order to investigate guided wave behavior on multilayered structures. In this thesis, guided waves were investigated using the Semi-Analytical Finite Element (SAFE) approach on planar (plate like) structures. The guided wave theory and dispersive behavior in bounded structure were presented for Lamb waves for isotropic elastic plate model first. The numerical method to solve the SAFE problem was developed using the Matlab 2014b in order to obtain dispersion curves. The curves were compared with the Disperse Software, which utilizes global matrix approach for analytical solution of the same pro...

Research paper thumbnail of Effect of mechanical vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migration

Eye, 2002

vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migr... more vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migration Abstract Purpose To investigate keratocyte apoptosis and polymorphonuclear (PMN) cell infiltration to the corneal stroma after mechanical epithelial scraping and chemical de-epithelialization with 18% ethanol solution. Methods Twelve New Zealand Albino rabbits (24 eyes) were randomly divided into three groups. Group A was the control group with no epithelial removal. Group B underwent a 7.5-mm mechanical epithelial removal with a blunt spatula. Group C underwent 7.5-mm chemical deepithelialization with 18% ethanol-balanced salt solution. Corneas were stained with terminal deoxyribonucleotidyl transferasemediated dUTP-digoxigenin nick-end labeling (TUNEL) assay after 24 h. Only nuclear staining in keratocytes was counted. Polymorphonuclear (PMN) leukocyte densities were also assessed by light microscopy. Results Mechanical de-epithelialization (group B) and chemical de-epithelialization with 18% ethanol (group C) showed no difference in keratocyte apoptosis compared with the control group. There was also no difference between groups B and C. Group B showed no difference in PMN leukocyte counts compared with the control group. But the number of PMN leukocytes observed in group C was significantly higher than those encountered in the corneas of the control group (P Ͻ 0.05) and group B (P Ͻ 0.05). Conclusions Dilute alcohol induces more PMN cell infiltration when compared with mechanical de-epithelialization although there is no difference in the apoptosis rates.

Research paper thumbnail of Effect of mechanical vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migration

Eye, 2002

vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migr... more vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migration Abstract Purpose To investigate keratocyte apoptosis and polymorphonuclear (PMN) cell infiltration to the corneal stroma after mechanical epithelial scraping and chemical de-epithelialization with 18% ethanol solution. Methods Twelve New Zealand Albino rabbits (24 eyes) were randomly divided into three groups. Group A was the control group with no epithelial removal. Group B underwent a 7.5-mm mechanical epithelial removal with a blunt spatula. Group C underwent 7.5-mm chemical deepithelialization with 18% ethanol-balanced salt solution. Corneas were stained with terminal deoxyribonucleotidyl transferasemediated dUTP-digoxigenin nick-end labeling (TUNEL) assay after 24 h. Only nuclear staining in keratocytes was counted. Polymorphonuclear (PMN) leukocyte densities were also assessed by light microscopy. Results Mechanical de-epithelialization (group B) and chemical de-epithelialization with 18% ethanol (group C) showed no difference in keratocyte apoptosis compared with the control group. There was also no difference between groups B and C. Group B showed no difference in PMN leukocyte counts compared with the control group. But the number of PMN leukocytes observed in group C was significantly higher than those encountered in the corneas of the control group (P Ͻ 0.05) and group B (P Ͻ 0.05). Conclusions Dilute alcohol induces more PMN cell infiltration when compared with mechanical de-epithelialization although there is no difference in the apoptosis rates.

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