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Predicting uniaxial compressive strength of tuff after accelerated freeze-thaw testing: Comparative analysis of regression models and artificial neural networks

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Journal of Mountain Science 2024年第10期21卷 3521-3535页

作者： Ogün ozan VAROL Department of Mining Engineering Faculty of EngineeringVan Yuzuncu Yil UniversityVan 65080Türkiye

Ignimbrites have been widely used as building materials in many historical and touristic structures in the Kayseri region of Türkiye. Their diverse colours and textures make them a popular choice for modern construction as well. However, ignimbrites are particularly vulnerable to atmospheric conditions, such as freeze-thaw cycles, due to their high porosity, which is a result of their formation process. When water enters the pores of the ignimbrites, it can freeze during cold weather. As the water freezes and expands, it generates internal stress within the stone, causing micro-cracks to develop. Over time, repeated freeze-thaw (F-T) cycles lead to the growth of these micro-cracks into larger cracks, compromising the structural integrity of the ignimbrites and eventually making them unsuitable for use as building materials. The determination of the long-term F-T performance of ignimbrites can be established after long F-T experimental processes. Determining the long-term F-T performance of ignimbrites typically requires extensive experimental testing over prolonged freeze-thaw cycles. To streamline this process, developing accurate predictive equations becomes crucial. In this study, such equations were formulated using classical regression analyses and artificial neural networks (ANN) based on data obtained from these experiments, allowing for the prediction of the F-T performance of ignimbrites and other similar building stones without the need for lengthy testing. In this study, uniaxial compressive strength, ultrasonic propagation velocity, apparent porosity and mass loss of ignimbrites after long-term F-T were determined. Following the F-T cycles, the disintegration rate was evaluated using decay function approaches, while uniaxial compressive strength (UCS) values were predicted with minimal input parameters through both regression and ANN analyses. The ANN and regression models created for this purpose were first started with a single input value and then dev

关键词： Ignimbrite Uniaxial compressive strength Freeze-thaw Decay function Regression Artificial neural network

Partitioning Anatolian Kinematics into Tectonic Escape and Slab Rollback Dominated Domains

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Journal of Earth Science 2024年第3期35卷 758-768页

作者： Jiannan Meng Timothy M.Kusky Erdin Bozkurt Hao Deng ozan Sinoplu State Key Laboratory of Geological Processes and Mineral Resources Center for Global TectonicsSchool of Earth SciencesChina University of GeosciencesWuhan 430074China Badong National Observatory and Research Station for Geohazards China University of GeosciencesWuhan 430074China Department of Geological Engineering Middle East Technical University06800 AnkaraTurkey Department of Geosciences Auburn UniversityAuburn AL 36849USA

Anatolia is the global archetype of tectonic escape,as witnessed by the devastating 2023 Kahramanmaraş Earthquake sequence,and the 2020 Samos Earthquake,which show different kinematics related to the framework of the escape *** Positioning System(GPS)motions of the wedge-shaped plate differ regionally from northwestwards to southwestwards(from east to west).Anatolia was extruded westward from the Arabian-Eurasian collision along the North and East Anatolian fault systems,rotating counterclockwise into the oceanic free-faces of the Mediterranean and Aegean,with dramatic extension of western Anatolia in traditional ***,which is the dominant mechanism for this change in kinematics,extrusion related to the Arabia/Eurasia collision or rollback of the African slab beneath western Anatolia is still *** assess the dominant driving mechanisms across Anatolia,we analyze recent GPS velocity datasets,and decomposed them into N-S and E-W components,revealing that westward motion is essentially constant across the whole plate and consistent with the slip rates of the North and East Anatolia fault zones,while southward components increase dramatically in the transition area between central and western Anatolia,where a slab tear is *** phenomenon is related to different tectonic driving *** ArabiaEurasia collision drives the Anatolian Plate uniformly westwards while western Anatolia is progressively more affected by the southward retreating African subducting slab west of the Aegean/Cypriot slab tear,which significantly increases the southward component of the velocity field and causes the apparent curve of the whole modern velocity *** 2020 and 2023 earthquake focal mechanisms also confirm that the northward colliding Arabian Plate forced Anatolia to the west,and the retreating African slab is pulling the upper plate of western Anatolian apart in *** propose that the Anatolian Plate is moving westwards as

关键词： tectonics neotectonics tectonic escape slab rollback Anatolian Plate GPS velocity field geodynamics.

Laser Surface Texturing of Co–Cr–Mo Alloy for Biomedical Applications:A Case Study for the Effects of Process Parameters on Surface Properties

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Journal of Bionic Engineering 2023年第5期20卷 1967-1984页

作者： Şefika Kasman İbrahim can Uçar Sertan ozan Department of Mechanical Engineering Dokuz Eylul UniversityIzmir35397Turkey Department of Mechanical Engineering Yozgat Bozok UniversityYozgat66100Turkey

This study presents a comprehensive approach to applying texturing processes created by engraving on the surface of CoCr28Mo alloy workpieces using a 20 W pulsed nanosecond fiber *** hatch strategy and distance,frequency,and scan speed were control parameters for texturing *** effectiveness of the parameters in terms of roughness and contact angle of the texturized surface was *** roughness and contact angle were analyzed using variance analysis to identify each variable's *** has been determined that the roughness of the texture defined by the hatch strategy plays a decisive role in the wettability behavior of the surface;however,the scan speed,frequency,and hatch distance which are among the laser surface texturing conditions are influential in the roughness and contact *** scan speed and hatch distance while decreasing frequency resulted in smoother surfaces,increasing the contact *** having rough surfaces produced with different processing conditions exhibit a super hydrophilic *** contact angle is most sensitive to the hatch distance;however,the frequency has the least influence on the contact *** most and least efficient surface roughness parameters are revealed to be scan speed and hatch distance,respectively.

关键词： Laser surface texturing Co-Cr-Mo alloy Surface roughness Wettability Bionic

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CES Transactions on Electrical Machines and Systems 2024年第3期8卷 241-243页

作者： Tayfun GUNDOGDU Udochukwu B.AKURU Zhongze WU Guven KOMURGOZ Erkan MESE Okan OZGONENEL ozan KEYSAN Mehmet Onur GULBAHCE Department of Electrical Engineering Tshwane University of Technology South Africa Southeast University Istanbul Technical University Ege University Ondokuz Mayis University Middle East Technical University

AS the world embarks on a path toward electrification and strives to achieve net-zero greenhouse gas emissions,the role of electrical machines becomes increasingly vital across various *** urgent need for decarbonization and improved energy efficiency has directed attention to rare-earth-free electrical machines as a promising *** technologies offer a sustainable alternative to permanent magnet-based machines,which rely heavily on rare earth materials like neodymium and *** extraction and processing of these materials result in hazardous by-products that cause significant ecological harm,particularly near mining sites and refineries.

关键词： solution rare earth

A case of solid pseudopapillary tumor of the pancreas

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World Journal of Gastroenterology 2006年第38期12卷 6239-6243页

作者： ozan Karatag Gulden Yenice Huseyin Ozkurt Muzaffer Basak can Basaran Banu Yilmaz Department of Radiology Sisli Etfal Education and Research Hospital Istanbul Turkey Department of Surgery Sisli Etfal Education and Research Hospital Istanbul Turkey Department of Pathology Sisli Etfal Education and Research Hospital Istanbul Turkey

We present ultrasound, computed tomography and magnetic resonance imaging findings in a case with pancreatic solid pseudopapillary tumor and their correlations with histopathology. Ultrasound revealed a hypoechogenic mass, and computed tomography revealed a hypodense mass at the pancreatic head minimally enhanced after intravenous contrast agent administration. Magnetic resonance imaging showed a hypointense mass on unenhanced Tl-weighted images including a hyperintense focus representing the hemorrhage. The lesion was hyperintense on T2- weighted images. On the postcontrast images the lesion showed peripheral thin contrast enhancement in arterial phase and enhanced slightly diffusely in venous and equilibrium phases. The patient underwent elective resection of the mass and pancreatoduodenectomy with jejunostomy tube placement. A final diagnosis of solid pseudopapillary tumor was made histoPathologically. Solid pseudopapillary tumor is a rare pancreatic tumor. It is important to make the diagnosis preoperatively because with an adequate surgical resection the prognosis is good. A multimodalitary approach, especially magnetic resonance imaging can suggest the diagnosis without the need for biopsy.

关键词： Pancreas Solid pseudopapillary tumor Magnetic resonance imaging Computed tomography Ultrasound

Casting properties of ASTM A128 Gr.E1 steel modified with Mn-alloying and titanium ladle treatment

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China Foundry 2021年第3期18卷 199-206页

作者： Uğur Gürol Erdal Karadeniz ozanÇoban Süleyman can Kurnaz Gedik Welding Company Ankara Caddesi34906İstanbulTurkey Sakarya University Engineering FacultyDepartment of Metallurgical&Materials EngineeringEsentepe Campus54187SakaryaTurkey Sakarya University Engineering FacultyDepartment of Mechanical EngineeringEsentepe Campus54187SakaryaTurkey Istanbul Gedik University Engineering FacultyDepartment of Metallurgical&Materials Engineering34876IstanbulTurkey

This work aims to produce a high manganese steel with more refined austenite grains and better wear resistance without sacrificing the toughness and tensile properties by Mn alloying and Ti ladle treatment in comparision to ASTM A128 Gr.E1 steel (1.0C-13Mn) that is mostly used in the mining *** 1.0C-17Mn-xTi alloys (x=0,0.05 and 0.1,in wt.%) were prepared.A relationship was established between the microstructures and mechanical properties of the as-cast and solution annealed *** Ti content increases the stable Ti(CN) phase on and beside the grain boundaries and decreases up to 37% the austenite grain size of the as-cast alloy with 0.10wt.% ***,after solution annealed,optimized titanium content (0.05wt.%) results in significant improvements in wear resistance,hardness,elongation,yield and tensile strengths by 44%,31%,30%,8% and 12%,respectively,except 9% decrease in impact toughness compared to ASTM A 128 Gr.E1 steel without *** results show that 1.0C-17Mn-0.05Ti alloy can be used for parts exposed to high load wear and applied in conditions where relatively high tensile properties with sufficent ductility is needed.

关键词： high manganese steel hadfield steel ladle treatment grain refinement microstructure mechanical properties

Flow structure at the downstream of a one-line riparian emergent tree along the floodplain edge in a compound open-channel flow

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Journal of Hydrodynamics 2018年第3期30卷 470-480页

作者： Ayse Yuksel ozan Civil Engineering Department Engineering Faculty Adnan Menderes University

This study focuses on the effects of one-line emergent natural tree（Cupressus Macrocarpa） planted at the edge of the floodplain in a compound open-channel flow. The flow velocity and water level are measured and used to analyze the flow structure. The time averaged and depth-averaged streamwise velocity distributions with root mean square（rms） and time series of streamwise velocity distrbution are analyzed. The velocity distribution considerably changes along the compound channel. The streamwise velocity distribution fits with logarithmic distribution in the non-vegetated case, but for vegetated cases, the streamwise velocity distribution shows S shaped profile at the 1/3 part of floodplain（/3）B_f and main channel（/3）B_m close to the boundary between floodplain and main channel. Additionally, it is obtained that the presence of tree line increases turbulence intensity over the compound open-channel. Moreover, an oscillation period is obtained in the flow caused by tree line by analyzing time series of the streamwise velocity distribution. The oscillation is present everywhere in the floodplain and present at almost/3 B_m part of the main channel which is close to the junction between floodplain and main channel.

关键词： Floodplain natural vegetation open channel flow compound channel velocity profile

Simulations of mass attenuation coefficients for shielding materials using the MCNP-X code

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Nuclear Science and Techniques 2017年第7期28卷 43-46页

作者： Huseyin ozan Tekin Tugba Manici Vocational School of Health Service Radiotherapy Department Uskudar University 34672 Istanbul Turkey Medical Radiation Research Center (USMERA) Uskudar University 34672 Istanbul Turkey

In this paper,mass attenuation coefficients of concrete,bricks and cement plaster,as shielding materials,are calculated at 59.5,356,662,1173,1274 and 1333 keV by using the MCNP-X(version 2.4.0) *** numerical simulation results are compared with previous Monte Carlo studies,experimental results and XCOM *** effects of barite on mass attenuation coefficients are *** mass attenuation coefficients increase with the barite ***,our results agree well with experimental studies on gamma ray shielding of *** is flexible for the MN method to change the barite rates in material by small increments,which is experimentally ***,modeled geometry can be used for future approaches such as new designs and new structures especially in investigating new barite-containing materials to build nuclear reactors or high-energy radiation therapy facilities.

关键词：质量衰减系数屏蔽材料数值模拟代码几何结构重晶石水泥砂浆蒙特卡罗

Performance evaluation of waste electrical and electronic equipment disassembly layout configurations using simulation

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Frontiers of Environmental Science & Engineering 2017年第5期11卷 65-75页

作者： ozan Capraz Olcay Polat Askiner Gungor Department of Industrial Engineering Naxmk Kemal University Corlu/Tekirdag 59860 Turkey Department of Industrial Engineering Pamukkale University Pamukkale/Denizli 20160 Turkey

Recycling of waste electrical and electronic equipment （WEEE） is crucially important since it handles hazardous waste according to ever tightening laws and regulations and it adds benefits to economy and sustainable environment. Disassembly is one of the most important processes performed during the recovery of WEEE. The overall goal of disassembly is to maximize the retrieval of various metals and plastics contained in WEEE in order to reduce their negative effects on human health and environmental sustainability and to increase economic gains. This study aims to evaluate alternative layout configurations for WEEE disassembly systems （WDS）. In this context, various configurations were compared in terms of pre-defined performance criteria, such as the total number of disassembled WEEE and the total revenue from sales, using simulation models. The results of this study show that the perfomaance of a WDS was significantly affected by output transfer systems along with the specialization of operators on certain types of WEEE.

关键词： WEEE Recovery Disassembly Layout planning Simulation