Crack detection in folded plates with back-propagated artificial neural network

Oguzhan Das,Can Gonenli,Duygu Bagci Das 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.3

Localizing damages is an essential task to monitor the health of the structures since they may not be able to operate anymore. Among the damage detection techniques, non-destructive methods are considerably more preferred than destructive methods since damage can be located without affecting the structural integrity. However, these methods have several drawbacks in terms of detecting abilities, time consumption, cost, and hardware or software requirements. Employing artificial intelligence techniques could overcome such issues and could provide a powerful damage detection model if the technique is utilized correctly. In this study, the crack localization in flat and folded plate structures has been conducted by employing a Backpropagated Artificial Neural Network (BPANN). For this purpose, cracks with 18 different dimensions in thin, flat, and folded structures having 150 , 300 , 450 , and 600 folding angle have been modeled and subjected to free vibration analysis by employing the Classical Plate Theory with Finite Element Method. A Four-nodded quadrilateral element having six degrees of freedom has been considered to represent those structures mathematically. The first ten natural frequencies have been obtained regarding healthy and cracked structures. To localize the crack, the ratios of the frequencies of the cracked flat and folded structures to those of healthy ones have been taken into account. Those ratios have been given to BPANN as the input variables, while the crack locations have been considered as the output variables. A total of 500 crack locations have been regarded within the dataset obtained from the results of the free vibration analysis. To build the best intelligent model, a feature search has been conducted for BAPNN regarding activation function, the number of hidden layers, and the number of hidden neurons. Regarding the analysis results, it is concluded that the BPANN is able to localize the cracks with an average accuracy of 95.12%.

Long-Term Substance Use Can Cause Irreversible Photopic Vision Changes in Substance Use Disorder in Remission

Oguzhan Bekir Egilmez,Mehmet Hamdi Orum,Ali Kustepe,Ayse Sevgi Karadag,Aysun Kalenderoglu 대한신경정신의학회 2020 PSYCHIATRY INVESTIGATION Vol.17 No.10

Objective Substance use has such effects on pupil diameter. Although there is knowledge about the acute effects of substances on pupils, studies showing their chronic effects are limited. The aim of the present study was to evaluate the effect of long-term substance use on scotopic, mesopic, and photopic vision.Methods The present study with cross-sectional desgn was conducted at the Adiyaman Training and Research Hospital for Psychiatry in Adiyaman. This study involved 110 substance use disorder (SUD) patients and 46 healthy volunteers as the control. The parameters were measured and recorded automatically by a device.Results The mean age was 23.44±5.53 years in the SUD group and 24.26±5.38 years in healthy controls (p=0.420). The mean age of onset of the substance was 17.74±3.89 years and the mean duration of substance use was 3.54±2.9 years. It was determined that the patients had not used any substance for a mean of 121.73±117.49 days. There was no significant difference between patient and control groups in terms of scotopic and mesopic measurements of both eyes (p>0.05). Photopic measurements were significantly higher in the patient group than in the control group (p<0.05). Photopic measurements were significantly higher in the opioid, cannabis, ecstasy, and multiple substance use groups than in the control group (p<0.05).Conclusion The most important topic of this study is that photopic vision is permanently impaired in patients with a history of chronic substance use. This was attributed to disrupted sympathetic-parasympathetic hierarchy.

Development of a cold wire-feed additive layer manufacturing system using shaped metal deposition method

Oguzhan Yilmaz,Adnan A. Ugla 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.4

Shaped metal deposition (SMD) method would be an alternative way to traditional manufacturing methods, especially for complex featured and large scale solid parts and it is particularly used for aerospace structural components, manufacturing and repairing of die/molds and middle-sized dense parts. This method is implemented by depositing continuous cold or hot-water melted via welding arc plasma heat. This paper presents the designing, constructing, and controlling of an additive manufacturing system using TIG plus wire based Shaped metal deposition (TW-SMD) method. The aim of the current study is to design and develop an integrated system which is able to reduce time consuming and boring task of deposition process. The developed additive system is capable of producing near net shaped components of sizes not exceed 400 mm in 3 directions directly from CAD drawing. The results showed that the developed system succeeded to produce near net geometries and error-free depositions for various features of SS308LSi components. Additionally, workshop tests have been conducted in order to verify the capability and reliability of the developed AM system.

Free vibration and buckling analyses of curved plate frames using finite element method

Oguzhan Das,Hasan Ozturk,Can Gonenli 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.86 No.6

This study investigates the free vibration and buckling analyses of isotropic curved plate structures fixed at all ends. The Kirchhoff-Love Plate Theory (KLPT) and Finite Element Method (FEM) are employed to model the curved structure. In order to perform the finite element analysis, a four-node quadrilateral element with 5 degrees of freedom (DOF) at each node is utilized. Additionally, the drilling effect (θz) is considered as minimal to satisfy the DOF of the structure. Lagrange's equation of motion is used in order to obtain the first ten natural frequencies and the critical buckling values of the structure. The effects of various radii of curvatures and aspect ratio on the natural frequency and critical buckling load values for the single-bay and twobay curved frames are investigated within this scope. A computer code based on finite element analysis is developed to perform free vibration and buckling analysis of curved plate frames. The natural frequency and critical buckling load values of the present study are compared with ANSYS R18.2 results. It has been concluded that the results of the present study are in good agreement with ANSYS results for different radii of curvatures and aspect ratio values of both single-bay and two-bay structures.

Finite element vibration analysis of laminated composite parabolic thick plate frames

Oguzhan Das,Hasan Ozturk,Can Gonenli 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.1

In this study, free vibration analysis of laminated composite parabolic thick plate frames by using finite element method is introduced. Governing equations of an eigenvalue problem are obtained from First Order Shear Deformation Theory (FSDT). Finite element method is employed to obtain natural frequency values from the governing differential equations. The frames consist of two flat square plates and one singly curved plate. Parameters like radii of curvature, aspect ratio, ply orientation and boundary conditions are investigated to understand their effect on dynamic behavior of such a structure. In addition, multi-bay structures of such geometry with different stacking order are also taken into account. The composite frame structures are also modeled and simulated via ANSYS to verify the accuracy of the present study.

Elevated Neutrophil-to-Lymphocyte Ratio in Squamous Cell Carcinoma of Larynx Compared to Benign and Precancerous Laryngeal Lesions

Kum, Rauf Oguzhan,Ozcan, Muge,Baklaci, Deniz,Kum, Nurcan Yurtsever,Yilmaz, Yavuz Fuat,Gungor, Volkan,Unal, Adnan Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.17

Background: Laryngeal carcinogenesis is a multifactorial process that has not been fully elucidated. Despite extensive research, reliable markers with diagnostic and prognostic value are still lacking. It was recently reported that an elevated preoperative neutrophil-to-lymphocyte ratio (NLR) may correlate with an increased risk of recurrence, tumor aggressiveness and poorer prognosis in various malignancies. The aim of this study was to examine whether NLR could be used as an inflammatory marker to differentiate laryngeal squamous cell carcinoma (LSCC) patients from benign laryngeal lesion (BLL) and precancerous laryngeal lesion (PLL) patients. Materials and Methods: This retrospective study was performed on 209 patients admitted to a tertiary referral center with laryngeal lesions and undergoing biopsies to establish their histopathological diagnosis. We reviewed the patient files for their clinical, histopathological and laboratory data. The patients were divided into three groups according to their histopathological findings, as BLL, PLL and LSCC groups. The patients in the PLL group were also divided into three subgroups as mild, moderate and severe dysplasia/carcinoma in situ (CIS) subgroups. The groups were compared for NLR and the other laboratory data. Results: The mean NLRs of the BLL, PLL and the LSCC groups were $2.12{\pm}0.86$, $2.32{\pm}0.68$ and $3.46{\pm}1.51$, respectively, and the difference was statistically significant (p=0.001). The mean NLRs of the patients with PLL and LSCC were significantly higher than the patients with BLL (p=0.031 and p=0.001, respectively). The mean NLRs were similar among mild dysplasia, moderate dysplasia and severe dysplasia / CIS groups (p>0.05). Conclusions: To our knowledge, this is the first study investigating NLR in BLL, PLL and LSCC. NLR is an inexpensive, reproducible and widely available blood test, and could be a useful inflammatory marker to differentiate LSCC from BLL and PLL.

Free vibration analysis of plates resting on elastic foundations using modified Vlasov model

Ayvaz, Yusuf,Oguzhan, Celal Burak Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.28 No.6

An application is presented of a modified Vlasov model to the free vibration analysis of plates resting on elastic foundations. The effects of the subsoil depth, the ratio of the plate dimensions, the ratio of the subsoil depth to the plate dimension in the longer direction, and the value of the vertical deformation parameter within the subsoil on the frequency parameters of plates on an elastic foundation are investigated. This analysis has been caried out by the aid of a computer program. The first ten frequency parameters are presented in tabular and the graphical forms to evaluate the effects of the parameters considered in this study. Then mode shapes corresponding to the first six of the frequency parameters are given in graphs. It is concluded that the effect of the subsoil depth on the frequency parameters of the plates on an elastic foundation is generally larger than those of the other parameters considered in this study.

Fragility-based rapid earthquake loss assessment of precast RC buildings in the Marmara region

Ali Yesilyurt,Oguzhan Cetindemir,Seyhan O. Akcan,Abdullah C. Zulfikar 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.1

Seismic risk assessment studies are one of the most crucial instruments for mitigating casualties and economic losses. This work utilizes fragility curves to evaluate the seismic risk of single-story precast buildings, which are generally favored in Marmara’s organized industrial zones. First, the precast building stock in the region has been categorized into nine sub-classes. Then, seven locations in the Marmara region with a high concentration of industrial activities are considered. Probabilistic seismic hazard assessments were conducted for both the soil-dependent and soil-independent scenarios. Subsequently, damage analysis was performed based on the structural capacity and mean fragility curves. Considering four different consequence models, 630 sub-class-specific loss curves for buildings were obtained. In the current study, it has been determined that the consequence model has a significant impact on the loss curves, hence, average loss curves were computed for each case investigated. In light of the acquired results, it was found that the loss ratio values obtained at different locations within the same region show significant variation. In addition, it was observed that the structural damage states change from serviceable to repairable or repairable to unrepairable. Within the scope of the study, 126 average loss functions were presented that could be easily used by non-experts in earthquake engineering, regardless of structural analysis. These functions, which offer loss ratios for varying hazard levels, are valuable outputs that allow preliminary risk assessment in the region and yield sensible outcomes for insurance activities.

Effect of laparoscopic cholecystectomy techniques on postoperative pain

Huseyin Yilmaz,Oguzhan Arun,Seza Apiliogullari,Fahrettin Acar,Husnu Alptekin,Akın Calisir,Mustafa Sahin 대한외과학회 2013 Annals of Surgical Treatment and Research(ASRT) Vol.85 No.4

Purpose: Minimally invasive surgical technics have benefits such as decreased pain, reduced surgical trauma, and increased potential to perform as day case surgery, and cost benefit. The primary aim of this prospective, randomized, controlled study was to compare the effects of single incision laparoscopic cholecystectomy (SILC) and conventional laparoscopic cholecystectomy (CLC) procedures regarding postoperative pain. Methods: Ninety adult patients undergoing elective laparoscopic cholecystectomy were included in the study. Patients were randomized to either SILC or CLC. Patient characteristics, postoperative abdominal and shoulder pain scores, rescue analgesic use, and intraoperative and early postoperative complications were recorded. Results: A total of 83 patients completed the study. Patient characteristics, postoperative abdominal and shoulder pain scores and rescue analgesic requirement were similar between each group except with the lower abdominal pain score in CLC group at 30th minute (P = 0.04). Wound infection was seen in 1 patient in each group. Nausea occurred in 13 of 43 patients (30%) in the SILC group and 8 of 40 patients (20%) in the CLC group (P > 0.05). Despite ondansetron treatment, 6 patients in SILC group and 7 patients in CLC group vomited (P > 0.05). Conclusion: In conclusion, in patients undergoing laparoscopic surgery, SILC or CLC techniques does not influence the postoperative pain and analgesic medication requirements. Our results also suggest that all laparoscopy patients suffer moderate and/or severe abdominal pain and nearly half of these patients also suffer from some form of shoulder pain.

Relationship between SSRIs and Metabolic Syndrome Abnormalities in Patients with Generalized Anxiety Disorder: A Prospective Study

Murat Beyazyuz,Yakup Albayrak,Oguzhan Bekir Egilmez,Neslihan Albayrak,Elmas Beyazyuz 대한신경정신의학회 2013 PSYCHIATRY INVESTIGATION Vol.10 No.2

Objective-SSRIs are some of the most widely prescribed medications in the world. In addition to their effectiveness, SSRIs were reported to be associated with the side effects of weight gain, sexual dysfunction, drug interactions, extrapyramidal symptoms and discontinuation symptoms. However, the effects of SSRIs on metabolic parameters are poorly understood. Methods-This study aims to describe the effects of SSRIs on the metabolic parameters of drug-naive first episode patients with generalized anxiety disorder. Ninety-seven female patients aged 20-41 years without any metabolic or psychiatric comorbidity were included in the study. Fluoxetine, sertraline, paroxetine, citalopram and escitalopram were randomly given to the patients. Metabolic parameters, including BMI, waist circumference and the levels of fasting glucose, total cholesterol, triglyceride, HDL, LDL and blood pressure, were measured before and after 16 weeks of treatment. Results-In the paroxetine group, there was a significant increase in the parameters of weight, BMI, waist circumference, fasting glucose, total cholesterol, LDL and triglyceride after 16 weeks of treatment. There were significant increases in the levels of triglyceride in the citalopram and escitalopram groups. In the sertraline group, the total cholesterol level increased after treatment. In the fluoxetine group, there were significant reductions in the parameters of weight, total cholesterol and triglyceride. Conclusion-To our knowledge, this study is the first to prospectively describe metabolic syndrome abnormalities in patients with first episode generalized anxiety disorder. Although the effectiveness of the different SSRIs is similar, clinicians should be more careful when prescribing SSRIs to patients who have cardiac risk factors. Larger and lengthier controlled clinical trials are needed to explore the associations between SSRI use and metabolic syndrome.