Examination of contact problem between functionally graded punch and functionally graded layer resting on elastic plane

Alper Polat 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.2

In this study, continuous contact problem in the functionally graded (FG) layer loaded with a FG flat punch resting on the elastic semi-infinite plane was analyzed by the finite element method (FEM). It was assumed that the shear modulus and density of the layer and punch varied according to exponentially throughout their depth. FG layer’s weight was included to the problem and additionally all surfaces were considered as frictionless. Analysis of FG materials was performed with a special macro which was added to the ANSYS program. Firstly, the shear modulus of the punch was considered to be very rigid and the results of initial separation load (λcr) and distance (xcr) were compared with the analytical solution. Afterwards, results obtained from the contact analysis made according to the inhomogeneity parameters (β, γ) between FG punch-FG layer which had been unprecedented in the literature were discussed. As a result, FG punch’s stress values at the punch edges where stress accumulations occurred were found to be smaller than the rigid punch. The security of the structure, longer life of the material and ease of production are directly related to the reduction of the stress values. The results obtained in this study are important in this respect. Also this work is the first study that investigates the effect of FG punch on the FG layer.

Anti-tank impact absorption with a reinforced concrete plate design

Berivan Yilmazer Polat,Sedat Savas,Alper Polat Techno-Press 2023 Advances in concrete construction Vol.15 No.4

Anti-tank weapons are among the infantry weapons used by the armies of many countries. Anti-tank rockets and explosives such as TNT, generally used for armour piercing, are also frequently used in terrorist attacks. These attacks damage the protection facilities built from reinforced concrete. Rockets or similar explosives' rapid speed and burst temperatures pierce reinforced concrete during strikes, resulting in casualties and damage to crucial strategic structures. This study aimed to devise an economic and applicable reinforced concrete plate that could absorb the impact of anti-tank rockets and Trinitrotoluene (TNT) type explosives. Therefore, 5 different samples, produced from C50 reinforced concrete and 150×150 cm in size, were formed by combining plates of different numbers and thicknesses. Also, a sample, which was a single thick plate, was prepared. In destructive testing, Rocket Propelled Grenade (RPG-7) was used as the anti-tank rocket launcher. As a result of this study, the impact damage was reduced with hollow concrete plate geometries, and recommendations were developed for complete prevention.

Standardized Uptake Values Highly Correlate with Tumor Size and Fuhrman Grade in Patients with Clear Cell Renal Cell Carcinoma

Polat, Emre Can,Otunctemur, Alper,Ozbek, Emin,Besiroglu, Huseyin,Dursun, Murat,Ozer, Kutan,Horsanali, Mustafa Ozan Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.18

Background: We investigated the correlation between standardized uptake value (SUVmax), tumor size and Fuhrman grade in patients with renal cell carcinoma (RC). Materials and Methods: We retrospectively analyzed the data of 54 patients with clear cell renal cell carcinoma histopathologically diagnosed who underwent fluorine-18 fluoro-2 deoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) between January 2005 and March 2014. Results: Avarage tumor sizes were $5.64{\pm}1.85$, $6.85{\pm}2.24$ and $7.98{\pm}2.45$ in low, medium and high SUVmax groups, respectively. The Spearman's correlation coefficient between the tumor size and SUVmax was 0.385 (p=0.004) and between the Fuhrman grade and SUVmax was 0.578 (p<0.001). Conclusions: SUVmax appears highly correlated with tumor size and Fuhrman grade in patients with histopathologically confirmed clear cell RC. Multicenter studies are needed to provide larger series for more accurate results.

Shilling Attacks Against Memory-Based Privacy-Preserving Recommendation Algorithms

( Ihsan Gunes ),( Alper Bilge ),( Huseyin Polat ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.5

Privacy-preserving collaborative filtering schemes are becoming increasingly popular because they handle the information overload problem without jeopardizing privacy. However, they may be susceptible to shilling or profile injection attacks, similar to traditional recommender systems without privacy measures. Although researchers have proposed various privacy-preserving recommendation frameworks, it has not been shown that such schemes are resistant to profile injection attacks. In this study, we investigate two memory-based privacy-preserving collaborative filtering algorithms and analyze their robustness against several shilling attack strategies. We first design and apply formerly proposed shilling attack techniques to privately collected databases. We analyze their effectiveness in manipulating predicted recommendations by experimenting on real data-based benchmark data sets. We show that it is still possible to manipulate the predictions significantly on databases consisting of masked preferences even though a few of the attack strategies are not effective in a privacy-preserving environment.

Renal Cell Carcinoma is More Aggressive in Turkish Patients with the Metabolic Syndrome

Ozbek, Emin,Otunctemur, Alper,Sahin, Suleyman,Dursun, Murat,Besiroglu, Huseyin,Koklu, Ismail,Polat, Emre Can,Erkoc, Mustafa,Danis, Eyyup,Bozkurt, Muammer Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.12

Background: Metabolic syndrome (MetS) is a multifactorial disease characterized by impaired glucose tolerance/diabetes, obesity, high triglyceride levels, low HDL levels, and hypertension. In this study we evaluate the relationship between tumor size and grade, and presence of the metabolic syndrome in patients with renal cell carcinoma. Materials and Methods: Between 2007-2013, radical nephrectomy was performed for 310 patients with renal tumors in our clinic and those with pathology reported renal cell carcinoma were enrolled and divided into two groups, with and without metabolic syndrome diagnosed on the basis of the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) criteria. The relationship between tumor size and grade of the two groups (Fuhrman nuclear degree) was evaluated statistically. Results: The metabolic syndrome was found in 70 patients, with a mean age of 65.5 (40-87), as compared to 58.8 (31-84) years in the non-metabolic syndrome group. Tumor size over 7 cm was found in 54% and 33%, respectively, and tumor grade over Fuhrman 3 in 56% and 32% of patients. Patients with metabolic syndrome had significantly higher tumor size and grade (p<0.05). In the presence of hypertension, diabetes and high triglyceride levels, significant assocations were again observed (p<0.05). Tumor size and degree also increased with increasing body mass index but this was not statistically significant (p>0.05). Conclusions: Renal cancer is more aggressive in patients with metabolic syndrome. Lifestyle and risk factors were revealed to be significant influences in renal cancer patients.

Long-term outcomes of intraoperative and perioperative albendazole treatment in hepatic hydatidosis

Kagan Karabulut,G. Selcuk Ozbalci,Tugrul Kesicioglu,Ismail Alper Tarim,Gokhan Lap,Ayfer Kamali Polat,Ilhan Karabıcak,Kenan Erzurumlu 대한외과학회 2014 Annals of Surgical Treatment and Research(ASRT) Vol.87 No.2

Purpose: The aim of this study was to evaluate long-term outcome of the intraoperative and perioperative albendazole (ALB) treatment on the recurrence and/or secondary hydatidosis. Methods: One hundred and one patients with hepatic hydatidosis were treated intraoperatively and perioperatively with ALB, in addition to surgery. Perioperative ALB treatment was given in a dose of 12?15 mg/kg/day. The ALB treatment was started 13.27 ± 14.34 days before the surgery, and it was continued for 4.39 ± 3.11 months postoperatively. A total of 1.7 mg/mL of ALB solution was used as a protoscolidal agent. The follow-up period was 134.55 ± 51.56 months. Results: Four patients died, with only one death was secondary to hydatid disease (cerebral eccinococcus). There was only one recurrence (1%) of hepatic hydatidosis. Early and late morbidity rates were 8.91% and 7.92%, respectively. Conclusion: Our results suggest that intraoperative and perioperative ALB is effective for the prevention of hepatic hydatidosis recurrence and/or secondary hydatidosis.