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Review Citation - WoS: 7Citation - Scopus: 8Stereotactic Radiosurgery After Subtotal Resection of Critically-Located Grade I Meningioma: a Single-Center Experience and Review of Literature(Turkish Neurosurgical Soc, 2021) Karaaslan, Burak; Celtikci, Emrah; Bulduk, Erkut Baha; Borcek, Alp Ozgun; Kurt, Gokhan; Kaymaz, Memduh; Emmez, HakanAIM: To analyze the results of stereotactic radiosurgery in 295 patients with residual Grade I meningiomas located at parasellar region, petroclival region, cerebellopontine angle and parasagittal region. MATERIAL and METHODS: A total of 295 patients with Grade 1 residual Meningiomas (197 women, 98 men), who were treated by adjuvant radiosurgery in Gazi University Gamma Knife Center between 2004-2015 were analyzed. WHO Grade 2 and 3 meningiomas were not included in our study. Minimum radiological follow-up was 24 months. The median follow-up was 54 months. The tumor volume, location, treatment dose, morbidity, progression free survival and tumor control rate were analyzed. RESULTS: The median tumor volume was 5.2 cm(3) (0.04-39.7), median age was 50 (20-80), median dose was 14 Gy and tumor control rate was 94.5% (stationary in 85.0%, volume reduction in 9.5%). Increase in tumor volume was seen in 16 patients (5.5%) and re-operation was performed in 5 of them (1.6%). Stereotactic radiosurgery was performed again for 8 patients (2.7%).The location of the tumors was as follows: 39.3% parasellar region, 20% cerebellopontine angle, 13.6% petroclival and 27.1% was parasagittal, falcine or convexity. Major morbidities were detected in 6 (2%) patients. Minor morbidities were detected in 18 (6.1%) patients. CONCLUSION: Stereotactic radiosurgery is an effective and safe treatment modality for residual Grade I meningiomas.Article Experimental Study and Theoretical Investigation of High Temperature Proton Exchange Membrane Fuel Cell Micro-Cogeneration Application(Turkish Soc thermal Sciences Technology, 2018) Devrim, Yilser; Ozgirgin Yapici, Ekin; Energy Systems EngineeringIn this study, a house hold micro-cogeneration system is designed using high temperature proton exchange membrane (HTPEM) fuel cell. HTPEM type fuel cells gain the highest interest lately, due to their advantages in terms of increasing efficiency and power quality, reducing harmful emissions and flexibility of operation with respect to the other fuels. The micro-cogeneration system involves producing both electrical energy and hot water and/or vapor together in an economical way, utilizing single fuel (HTPEM fuel cells) for household applications. During the operation of the fuel cell, for high efficiency and stable power production, the access heat of the stack should be removed constantly and the temperature of the stack should be held stable. Heat recovered from the designed innovative cooling system is used for acquiring energy for heating water. This way, thermal efficiency is almost doubled compared to simple cycle. In the scope of this study, 225 W HTPEM fuel cell stack is designed and tested at 160 degrees C operation temperature with hydrogen gas and air. During operation, for homogenous distribution of temperature among the cells, for a short start up period leading to a fast required steady state temperature and for constantly removing the access heat produced in the cell, the cell stack is cooled by using a cooling fluid (Heat Transfer Oil 32- Petrol Ofisi). Selection of insulation material type and thickness for the cell stack is done using natural convection and radiation loss calculations. For the most efficient operating conditions, micro-cogeneration system water inlet and exit temperatures, water and cooling fluid flow rates, convenient pipe diameter and pump power calculations are done to finalize the design. With the cogeneration system designed during the studies, by recovering the access heat of the insulated HTPEM cell stack, district water with initial temperature of 15-20 degrees C is heated around 50 degrees C. Data gathered during studies indicate that fuel cell micro-cogeneration application is highly viable.Article Citation - WoS: 2Citation - Scopus: 2Enhancing Classification Modeling Through Feature Selection and Smoothness: a Conic-Fused Lasso Approach Integrated With Mean Shift Outlier Modelling(Amer inst Mathematical Sciences-aims, 2025) Yerlikaya-Ozkurt, Fatma; Taylan, PakizeOutlier detection and variable selection are among main objectives of statistical analysis. In our study, we address the outlier problem for classification by using the Mean Shift Outlier Model (CLMSOM). Since the MSOM has more coefficients than the linear regression model, the complexity of the model MSOM is high. Therefore, we consider feature selection for MSOM by using fused Lasso (FLasso), which is beneficial and helpful in the cases where the number of explanatory variables or features is greater than the sample size. FLasso is penalizing both the coefficients and their successive differences by the L-1-norm, and it allows sparsity for both of them, while Lasso only allows the coefficients by considering a nonsmooth optimization problem. In this study, we take into account Iterated Ridge approximation which enables us to use a smooth optimization for FLasso problem. Generated smooth optimization problem is solved by using one of continuous optimization techniques called Conic Quadratic Programming (CQP), which is enabling the utilization of interior point methods. The newly developed method is called Conic FLasso for classification by MSOM (C-FLasso-CLMSOM) and is applied to real world data set to show its performance.Article Citation - WoS: 66Citation - Scopus: 77Generalized δ-shock model via runs(Elsevier Science Bv, 2012) Eryilmaz, SerkanAccording to the delta-shock model, the system fails when the time between two consecutive shocks falls below a fixed threshold delta. This model has a potential application in various fields such as inventory, insurance and system reliability. In this paper, we study run-related generalization of this model such that the system fails when k consecutive interarrival times are less than a threshold delta. The survival function and the mean value of the failure time of the system are explicitly derived for exponentially distributed interarrival times. We also propose a new combined shock model which considers both the magnitudes of successive shocks and the interarrival times. (C) 2011 Elsevier B.V. All rights reserved.Article Citation - WoS: 1Citation - Scopus: 1Sub-Linear Oscillations via Nonprincipal Solution(Editura Acad Romane, 2018) Ozbekler, Abdullah; MathematicsIn the paper, we give new oscillation criteria for forced sub-linear differential equations with "oscillatory potentials" under the assumption that corresponding linear homogeneous equation is nonoscillatory.Article Citation - WoS: 4Citation - Scopus: 4Simulation of Through-Hardening of Sae 52100 Steel Bearings - Part Ii: Validation at Industrial Scale(Wiley-v C H verlag Gmbh, 2016) Evcil, G. E.; Mustak, O.; Simsir, C.In this study, the material dataset presented in part I of this article is validated at industrial scale in batch through-hardening of bearing races. The material dataset acquired is implemented in a commercial heat treatment simulation software. Heat transfer coefficients for the oil and salt bath are determined by using a commercial standard quench probe. Zone temperatures and transfer times of the roller-belt furnace are measured directly from the system. Through-hardening of inner ring (IR) of 6813 bearing in oil and salt bath is simulated considering most of the industrial details. Finally, predicted dimensional changes are compared with the coordinate measurement results and a good agreement is achieved. It is concluded that determined material and process data, idealizations and simulation procedure can be considered "validated" for further improvement of the industrial process.Article 19. Yüzyılda Osmanlı ve Rus İmparatorluklarında Yerel Yönetim Reformu: 1864 Zemstvo Kanunu ve 1864 Vilayet Nizamnamesi Üzerine Karşılaştırmalı Bir Analiz(2022) Gülseven, Aslı YiğıtOsmanlı ve Rus İmparatorluklarının 19. yüzyılına damga vuran modernleşme süreci her iki devlette de kapsamlı bir reform hareketi başlatmıştı. 19. yüzyılın ortasında patlak veren Kırım Harbi neticesinde, Avrupalı devletlerin baskı ve müdahalelerinden çekinen her iki imparatorlukta da iktisadi refahın sağlanması yolunda idari düzenlemelerin ya-pılması öncelikli hedef haline gelmişti. Buradan hareketle, Osmanlı ve Rus İmparator-luklarında 19. yüzyılda etkin yönetim anlayışı çerçevesinde yerel yönetimlerde bir takım idari düzenlemeler meydana getirildi. Bir yandan yerel yönetimlerin faaliyet ve yetki alanlarının genişletilmesi anlayışı benimsenirken, diğer yandan her iki imparatorlukta da merkezi yönetimin güçlendirilmesi hedeflenmiştir. Bu çalışma, Osmanlı İmparatorlu-ğunda 1864 Vilayet Nizamnamesi ve Rus İmparatorluğunda 1864 Zemstvo Kanununun taşra örgütlenmesine getirdikleri yerel yönetim reformunu ortaya koymayı ve her iki dü-zenlemeyi tarihsel arka plan, içerik, kapsam ve etkinlik yönünden karşılaştırmalı olarak değerlendirmeyi amaçlamaktadır.Article Citation - Scopus: 48Identifying Phishing Attacks in Communication Networks Using Url Consistency Features(Inderscience Publishers, 2020) Azeez,N.A.; Salaudeen,B.B.; Misra,S.; Damasevicius,R.; Maskeliunas,R.Phishing is a fraudulent attempt by cybercriminals, where the target audience is addressed by a text message, phone call or e-mail, requesting classified and sensitive information after presenting himself/herself as a legitimate agent. Successful phishing attack may result into financial loss and identity theft. Identifying forensic characteristics of phishing attack can help to detect the attack and its perpetuators and as well as to enable defence against it. To shield internet users from phishing assaults, numerous anti-phishing models have been proposed. Currently employed techniques to handle these challenges are not sufficient and capable enough. We aim at identifying phishing sites in order to guard internet users from being vulnerable to any form of phishing attacks by verifying the conceptual and literal consistency between the uniform resource locator (URL) and the web content. The implementation of the proposed PhishDetect method achieves an accuracy of 99.1%; indicating that it is effective in detecting various forms of phishing attacks. © 2020 Inderscience Enterprises Ltd.. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 4Insights Into a New Paradigm in Translation Eco-Translation and Its Reflections(John Benjamins Publishing Co, 2020) Aksoy, Nuzhet BerrinThe purpose of this paper is to draw attention to the reflection and recreation of the physical landscape in literary texts and in their translations; to explore in what ways nature is represented and, secondly, to discuss aspects of this process in the light of the translational norms proposed by Toury. The focus is the idea that language and culture, the core of literature, are to be transferred to other linguistic and cultural mediums during translation, and constitute the ecological environment of the text. This undertaking assigns to the translator the task of selecting, adapting and recreating this material in the foreign environment. An ecocritical approach will be adopted to explore how and how far this task is materialized by studying a Turkish author Yasar Kemal's novel Ortadirek translated as The Wind from the Plain. Yasar Kemal is regarded as the most ecologically-minded author of Turkish literature and his novels portray nature as the mental landscapes of man, a force under which the constituents of the text are recreated at every linguistic and culture-bound effort of the author. Hence, the main endeavour of this study will be to bring to the surface, with an eco-critical approach, the translational preferences of the translator of Ortadirek and their significance in the recreation of Kemal's ecological vision in the translation.Article Citation - WoS: 12Citation - Scopus: 13A New Mixed Δ-Shock Model With a Change in Shock Distribution(Springer, 2023) Chadjiconstantinidis, Stathis; Tuncel, Altan; Eryilmaz, SerkanIn this paper, reliability properties of a system that is subject to a sequence of shocks are investigated under a particular new change point model. According to the model, a change in the distribution of the shock magnitudes occurs upon the occurrence of a shock that is above a certain critical level. The system fails when the time between successive shocks is less than a given threshold, or the magnitude of a single shock is above a critical threshold. The survival function of the system is studied under both cases when the times between shocks follow discrete distribution and when the times between shocks follow continuous distribution. Matrix-based expressions are obtained for matrix-geometric discrete intershock times and for matrix-exponential continuous intershock times, as well.
