Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 3Citation - Scopus: 3Nonlocal Static Modeling of Laminated Composite Shells Using Peridynamic Differential Operator in a Higher-Order Shear Deformation Framework(Elsevier Ltd, 2025) Bab, Yonca; Dorduncu, Mehmet; Kutlu, Akif; Markert, BerndThis study investigates the flexural behaviour of the laminated composite shells in the framework of Higher-Order Shear Deformation Theory (HSDT) and Peridynamic Differential Operator (PDDO), namely PD-HSDT, for the first time. Laminated composite shell structures are widely used in aerospace, automotive, and marine industries due to their high strength-to-weight ratio and design flexibility. Therefore, understanding their mechanical behavior under various loading conditions is crucial for ensuring structural reliability and performance optimization. However, such structures may possess complex curvatures and highly heterogenous laminate stackings, leading to inaccurate numerical stress analyses. The HSDT successfully captures displacement and stress distributions as well as cross-sectional warping through higher-order functions exist in the kinematics. Moreover, the PDDO represents the local derivatives in their nonlocal form, making it well-suited for problems involving higher-order derivatives and discontinuities. The governing equations and boundary conditions of the HSDT are solved by using the PDDO to accurately achieve the stress and displacement fields in the laminated composite shells. The robustness of the PD-HSDT is established by considering various loading and boundary conditions. The proposed approach demonstrates high accuracy in stress and displacement predictions when validated against reference solutions available in existing literature. This indicates strong potential for extending the methodology to more complex loading scenarios and damage mechanisms in future studies.Article Citation - WoS: 3Citation - Scopus: 3A Novel Hybrid Thin Jacketing Method for Seismic Retrofitting of Substandard Reinforced Concrete Columns(Elsevier Ltd, 2025) Narlitepe, Furkan; Kian, Nima; Demir, Ugur; Demir, Cem; Ilki, AlperThis paper introduces a novel hybrid thin jacketing method for seismic strengthening of substandard reinforced concrete (RC) columns for which structural repair mortar along with carbon fiber reinforced polymer (CFRP) and longitudinal steel bars are utilized. The method involves three application phases comprising a) removing the cover concrete, b) re-forming the cover concrete with structural repair mortar just after installing extra longitudinal steel bars c) transverse wrapping of CFRP sheets. The effect of using different types of structural repair mortar and its application process are other test parameters taken into account in this study. To evaluate the efficacy of the proposed method, a comprehensive experimental program was conducted, consisting of six largescale RC column specimens with square and rectangular cross-sections. For all of the specimens tested under a simultaneous constant axial load and reversed cyclic lateral loading, three main properties representing existing substandard RC columns such as a) insufficient transverse reinforcement, b) high axial load ratio (0.75) and, c) relatively high shear force corresponding to moment capacity to shear capacity ratios between 0.60 and 0.80, were considered. The responses of specimens were specified in terms of the lateral load-displacement curves, stiffness variation, ductility ratios, damage progression, and energy dissipation. The experimental results demonstrated that in case the retrofitting method is properly applied, the strengthened columns exhibit satisfactory performance in terms of strength and ductility with a remarkable improvement with respect to the substandard columns. Furthermore, a numerical study was conducted to validate the experimental results by using the OpenSees framework.Article Influence of Fluorine on Structural and Electrical Properties of VO2 Thin Films Deposited by Magnetron Sputtering(Elsevier Ltd, 2025) Akyurek, Bora; Cantas, Ayten; Demirhan, Yasemin; Ozyuzer, Lutfi; Aygun, GulnurThis study investigates whether fluorine-based thermal gel used during electrical measurements of vanadium oxide (VO2) films influences the structural, morphological, or compositional integrity of the films. High-quality VO2 films with a resistance ratio change of about 10(4) for metal-insulator transition were deposited by magnetron sputtering. During electrical characterization, VO2 film was heated from room temperature to similar to 370 K with a fluorine-based thermal gel usage to achieve better heat contact between the film and substrate holder. Structural and chemical properties were assessed through XRD, Raman, XPS, SEM, and energy dispersive spectroscopy imaging. XRD revealed diffraction peaks consistent with monoclinic VO2 confirming that the crystal lattice remains the same although fluorine based thermal gel was used. Raman spectra exhibited vibrational modes indicating that the phonon structure of VO2 was preserved despite fluorine gel usage. XPS results showed only a minor F 1s signal (2.8%) limited only to the film surface. SEM and EDS analyses further confirmed that surface morphology and elemental composition remained belonging to VO2 film. These findings demonstrate that the usage of fluorine-based thermal gel results in only a minimal surface interaction, thereby preserving intrinsic material properties of VO2 and supporting a potential usage for future device fabrication applications.Article Citation - WoS: 4Citation - Scopus: 2Elastic and Anelastic Behavior Associated With Structural Transitions in CsPbBr3(Amer Chemical Soc, 2025) Luo, Pingjing; He, Zhengwang; Yang, Dexin; Aktas, Oktay; Ding, Xiangdong; Zhang, XuefengStrain coupling and relaxation dynamics critically influence the photovoltaic and photoluminescent performances of metal halide perovskites. Here, resonant ultrasound spectroscopy is employed to study the elastic and anelastic properties associated with the octahedral tilting transitions in the optoelectronic semiconductor CsPbBr3 over the temperature range 303-468 K. The cubic-to-tetragonal transition near 405 K is marked by pronounced elastic softening accompanied by a sharp increase in acoustic loss. High anelastic loss below this transition reveals the presence of mobile ferroelastic twin walls that become pinned by lead vacancies at a temperature interval near 380 K in the tetragonal phase. The elastic softening in the cubic phase is strongly correlated to dynamic effects such as the local polar fluctuations. This local disordered effect is further verified by the anomalously high attenuation in the orthorhombic structure, in which the ferroelastic twin walls might become mobile.Article Citation - WoS: 2Citation - Scopus: 2Experimental Integration of Stone Topologies To the Simplified Micro-Modeling for the Seismic Response of Masonry Walls: a Novel Insight(Springer Heidelberg, 2025) Demir, UgurThis study aims to explore the impact of stone typologies on the in-plane seismic behavior of stone masonry buildings. The present study aims to quantify the strength and deformability parameters such as lateral load capacity, ductility, energy dissipation capacity and stiffness degradation of frequently used sandstone and limestone masonry, which will intentionally contribute to the core body of knowledge on their original structural design, seismic safety evaluation and intervention design. The innovative aspect of this research lies in the holistic methodology that integrates field surveys to classify local stone masonry units, experimental characterization of the chemical and mechanical properties of these units to capture variability, and finite element modeling of the in-plane cyclic behavior of stone masonry walls using experimental data. A novel simplified micro-modeling approach is implemented within a standard finite element software, eliminating the need for user-defined subroutines. This approach significantly reduces computational efforts compared to conventional methods, making it particularly suitable for analyzing large-scale stone masonry structures. The study investigates the impact of chemical composition (sandstone or limestone), applied axial stress (0.25 MPa, 0.50 MPa, or 1 MPa), and wall aspect ratios (height-to-length ratios of 1.0 or 1.5) on wall performance. The modeling approach is validated against experimental results from the literature, demonstrating good agreement. Finally, the study assesses wall performance in terms of deformation limits in current seismic codes. The findings provide critical insights for developing innovative design strategies to enhance the structural integrity of stone masonry walls and improve the seismic assessment of existing structures.Article Byzantine Wall Paintings in the Archaeological Sites of Aigai, Olympos, and Anaia (Turkey): Techniques and Material Characteristics(Routledge Journals, Taylor & Francis Ltd, 2025) Şerifaki, K.; Böke, H.The aim of this study is to determine the material characteristics of the paint layers and techniques of paintings executed in Late Roman and Byzantine churches located in the archaeological sites of Aigai, Olympos, and Anaia (Turkey) in order to select compatible materials prior to conservation treatments of the paintings and to establish the technical aspects of the paintings in relation to coeval Western examples. In this context, the execution technique, microchemical characteristics, stratigraphy of paintings, and mineralogical and chemical composition of the pigments were determined by polarized light microscopy (PLM), scanning electron microscopy coupled with X-ray energy dispersive spectroscopy (SEM-EDX), and Fourier transform infrared spectroscopy (FTIR). The analysis results indicated that wall paintings were executed by fresco, secco or fresco-secco techniques on a thin plaster layer that is composed of pure lime, straw, fine marble, brick, and sand aggregates. The ground layers of the paintings are composed of kaolin, calcite, and carbon black. The color compositions of the paintings were obtained by applying successive layers of paint on the ground layers. The pigments used in the paintings are mainly iron oxides for the red and yellow, green earth in celadonite and glauconite forms for greens, and lapis lazuli and Egyptian blue for blues. The present study demonstrates that the techniques and materials employed in the execution of wall paintings in Byzantine churches in Western Anatolia are analogous to those utilized in the Balkans, Crete, and Cyprus, with the exception of the presence of a clay-based ground. © The International Institute for Conservation of Historic and Artistic Works 2025.Article Citation - WoS: 1Tourist Guides Versus the Technology Threat(Routledge Journals, Taylor & Francis Ltd, 2025) Nazli, M.The study aims to understand the technology threat to the jobs of tourist guides and the way they perceive technology’s impact. An email interview method is preferred while collecting the data from 25 countries. The findings reveal that although many guides mentioned the essentiality of human touch in guidance, they are aware of the influence of AI, the metaverse and smart technologies. Loss of jobs is very much possible, according to the vast majority of guides. They believe that without training and adapting themselves to novel technologies like the metaverse, they will not attract new generations and guides may lose jobs due to a lack of applying new technology to their own ways of doing business. The study enlightens the tour guidance field and the metaverse perceptions of guides influencing jobs. © 2025 Informa UK Limited, trading as Taylor & Francis Group.Article Citation - WoS: 2Citation - Scopus: 1A Novel Framework for Droplet/Particle Size Distribution in Suspension Polymerization Using Physics-Informed Neural Network (PINN)(Elsevier Science Sa, 2025) Turan, Meltem; Dutta, AbhishekA Machine Learning (ML) based neural network can capture the complex evolution of polymer chain distributions, accounting for factors such as initiation, propagation, and termination steps in a suspension polymerization process, by integrating stagewise molar balance model (MBM) and population balance model (PBM) with Physics-Informed Neural Network (PINN). The integrated PINN framework is proposed to efficiently solve these equations, incorporating known physical laws as constraints and minimizing errors in both the distribution and dynamics of the polymer chains. By optimizing the neural network parameters such as weight matrices and bias vector, the model reproduces the moments of the polymer molecular weight distribution in close alignment with numerical solutions, and it generates population balance solutions that exhibit excellent agreement with their analytical counterparts. Sensitivity analyses for the depth of the neural network architecture to quantify how structural choices affect model fidelity has been performed. The resulting MBM-PINN and PBM-PINN integrated framework demonstrates robustness and versatility in accurately capturing (96-97%) droplet/particle dynamics. The proposed methodology has the capability to provide a powerful tool for faster and scalable simulations of polymerization reactions, enabling better prediction of product properties which could be used for optimizing reaction conditions in industrial applications.Article Citation - WoS: 3Citation - Scopus: 3Analysis of Microplastic Flux From the Gediz River To the Aegean Sea: a Modeling Study for Environmental Management(Academic Press Ltd- Elsevier Science Ltd, 2025) Kazanci, Yigithan; Alyuruk, Nefise; Alpergun, Cumana; Kara, Nursena; Baycan, Neval; Gunduz, OrhanIt is critical to determine the abundance of microplastics in terrestrial inland waters, understand their fate and transport mechanisms, and reveal their status in aquatic environments. This study aimed to develop and calibrate a mathematical model to simulate microplastic (MP) pollution in the Gediz River Basin, T & uuml;rkiye, which focused on MP fate and transport under existing conditions and various management scenarios. The baseline scenario revealed that, despite a ninefold difference in flow rates, the midstream and upstream parts of the basin also exhibited significant contamination, with an average concentration of 25 n/L compared to the downstream average of 29 n/L. The model was later simulated to test the effects of various mitigation scenarios including but not limited to reducing MP discharges from wastewater treatment plants (WWTPs) and implementing vegetative barriers in tributaries. Scenario 4, which involves reducing MP concentrations in upstream tributaries with vegetative barriers, achieved the highest average reduction across all segments (32 %) and specifically in the downstream area (47 %). In contrast, Scenario 1, aimed at reducing wastewater discharges from urban and industrial WWTPs through water reclamation, and Scenario 2, which focused on eliminating MP in Organized Industrial Zone (OIZ) discharges by changing industrial inputs, achieved the most effective MP reductions in the upper basin, with reductions of 20 % and 17 %, respectively. Scenario 3, targeting flow reduction and accumulation through constructed wetlands, had minimal impact, with reductions close to 0 % in most areas. These results highlight the need for comprehensive approaches to effectively reduce MP pollution, particularly in managing upstream and tributary sources.Article Citation - WoS: 2Citation - Scopus: 2Sintering Under High Heating Rates(Annual Reviews, 2025) Karacasulu, Levent; Maniere, Charles; Vakifahmetoglu, Cekdar; Marinel, Sylvain; Biesuz, MattiaRapid sintering using a high heating rate is growing in technological and scientific interest. This is motivated by the promise of reducing the carbon footprint of sintering and developing materials with properties and microstructures different from those achievable by conventional heating. For instance, rapid heating can induce suppression of grain growth, the possibility of obtaining modified space charges and elemental segregations, and the development of out-of-equilibrium materials. Severe challenges still exist for the industrial exploitation of rapid sintering technologies, and, nowadays, only fast firing can be considered mature. Most of these limitations are related to the homogeneity of the sample and the possibility of obtaining complex shapes. This review investigates developments in rapid sintering by comparing different processes, suggested mechanisms, and future challenges.