AGU GCRIS Premium Database (Abdullah Gül University)
Not a member yet
2706 research outputs found
Sort by
SUPS-Based Computational Investigation of Heat Transfer in a Nanofluid-Filled Cubic Enclosure With a Spherical Obstacle
No full textThis study investigates natural convection heat transfer through numerical simulations. The computational domain consists of a cubic enclosure filled with an Al2O3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}\end{document}-H2O\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}\end{document} nanofluid, containing a concentric sphere that may be either heated or cooled. Various configurations are analyzed by varying the Rayleigh number (103 3 \le \text {Ra} \le 105\end{document}) and the nanoparticle volume fraction (0.01 <=phi <= 0.1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}0.01 \le \phi \le 0.1\end{document}). The governing equations comprise the unsteady incompressible Navier-Stokes equations coupled with the heat transport equation. The Boussinesq approximation is employed, treating the density as constant except in the buoyancy term. To mitigate numerical instabilities inherent in the classical Galerkin finite element method (GFEM), a stabilized finite element formulation, known as the SUPS, is implemented. This formulation incorporates the streamline-upwind and pressure-stabilizing mechanisms. The proposed computational framework and in-house parallel incompressible flow solvers are validated against established benchmark cases, demonstrating good agreement despite using unstructured tetrahedral meshes without adaptive refinement. For the considered flow domain, the stabilized method ensures accurate solution profiles without significant spurious oscillations while substantially reducing computational cost, as linear interpolation functions are sufficient. Findings indicate that increasing the nanoparticle volume fraction enhances velocity magnitudes and the overall heat transfer rate around the sphere. Additionally, a slight reduction in the average number of nonlinear iterations is observed, suggesting improved computational efficiency. These results emphasize the effectiveness of stabilized finite element formulations in accurately and efficiently simulating convection-driven flow phenomena
Defence Industry Policies of Small and Medium Powers: An Introduction to the Challenges and Prospects
No full textThe urgency to better understand small and middle powers’ defence industrial activities is growing, both from a scholarly and a practitioner’s perspective. Few states today possess the defence industrial capabilities to produce all, or even most, of their armaments domestically. With rising development costs, greater complexity inherent in modern military technology, and intensified global market competition, the prospects for states aspiring to build up domestic defence industries, or sustain the ones they already have, look increasing poor. In the face of these strong headwinds many small- and medium-sized powers continue to pursue domestic arms production. What drives them to do so? In this introductory essay to the special issue, we provide an overview of some of the most significant developments in global arms production and how this shapes the choices states are making about their defence industries. © 2025 Elsevier B.V., All rights reserved
Enhanced Photoluminescence via Plasmonic Gold Nanoparticles and Improved Stability of Perovskite Nanocrystals in Macroporous (Polydimethylsiloxane) PDMS Matrices
No full textIn this work, we report a simple and cost-effective method for improving both the environmental stability and photoluminescence quantum efficiency (PLQY) of perovskite nanocrystals (PNCs). Through their embedding in a specially designed macroporous polydimethylsiloxane (MPDMS) matrix and incorporation of plasmonic gold nanoparticles (Au NPs), remarkable improvements are achieved. The resulting MPDMS@PNC composites are seen to retain near-unity quantum efficiency even after 24-h immersion in water and are observed to retain over 85% of the original efficiency even at 75 degrees C, displaying excellent thermal stability. More interestingly, by incorporating Au NPs and subjecting the material to mechanical pressure, the lifetime of the PNCs gets further increased. This is due to the more intimate spatial arrangement of Au NPs in the porous matrix, enhancing localized surface plasmon resonance (LSPR) coupling and thereby enhancing the photoluminescence (PL) of the PNCs. In general, this approach offers a scalable and robust route to designing stable, high-performance perovskite-based materials for next-generation optoelectronic applications.TUBITAK [20AG026]TUBITAK, 20AG026, Evren Mutlugu
Space-Time Geography
No full textThis is a definition of space-time geography in the Thematic Encyclopedia of Regional Science. This thematic Encyclopedia explores the multifaceted world of regional science, presenting a systematic and coherent overview of its central topics. It highlights the interdisciplinary nature of the field, examining the wide range of concepts, theories, methods and models that shape spatial-oriented approaches to the social sciences. Contributions from expert scholars delve into key aspects of regional science, from urban poverty and natural resource management to smart cities and AI. Highly accessible entries cover the definition, history, theoretical background, and applications of each topic, as well as avenues for future research. © 2025 Elsevier B.V., All rights reserved
Maintaining the Power in the Therapy Room: A Conceptual Model of Social Dominance Orientation, Medicalization and Overpathologizing
No full textBu tez, psikoterapide hiyerarşiye yönelik yönelimleri ifade eden Sosyal Baskınlık Yönelimi (SBY) ve sosyal normların ne ölçüde tıbbi açıklamalar yönünde değişmesi gerektiğine ve toplumun bu açıklamalar aracılığıyla ne kadar düzenlenmesi gerektiğine ilişkin görüşleri içeren medikalizasyon inançlarının aşırı patolojikleştirme üzerindeki rolünü incelemektedir. Bu çerçevede, çalışmanın modeli SBY'nin medikalizasyon inançları aracılığıyla terapistlerin aşırı patolojikleştirme eğilimlerini etkilediği yönündeki varsayımı test etmektedir. Çalışma 1'de çevrim içi bir platformda yer alan 1.675 ruh sağlığı uzmanına yönelik danışan şikâyeti analiz edilmiştir. Şikâyetler, aşırı patolojikleştirme içerip içermediğine göre kodlanmış ve aşırı ilaç yazma, aşırı tanı koyma, kötümser prognoz ve zorlayıcı tedavi temaları altında kategorize edilmiştir. Bulgular, aşırı patolojikleştirmenin mesleki pratikte de ortaya çıktığını göstermiştir. Çalışma 2'de, SBY'yi manipüle ederek, medikalizasyon inançlarını ve dolayısıyla aşırı patolojikleştirme eğilimlerini artırıp artırmayacağını test etmek amacıyla çevrim içi bir vinyet deneyi yürütülmüştür. Deney ve kontrol grupları arasında SBY, medikalizasyon inançları veya aşırı patolojikleştirme açısından anlamlı bir fark gözlenmemiştir. Ancak, medikalizasyon inançları ile aşırı patolojikleştirme arasında pozitif bir ilişki bulunmuş; medikalizasyonu daha güçlü benimseyen terapistlerin danışanları aşırı patolojikleştirme eğiliminde oldukları görülmüştür.This thesis examines how therapists' orientation towards social hierarchies and their medicalization beliefs shape the risk of overpathologizing in psychotherapy. Drawing on Social Dominance Orientation (SDO), it develops a conceptual model in which SDO influences clinical judgement through medicalizations, understood as an ideological framework that legitimizes expert authority. Study 1 analyzed 1,675 naturally occurring client complaints from a public platform using large language model-based text classification. The complaints were coded for overpathologizing and grouped into the themes of overprescribing, overdiagnosis, pessimistic prognosis, and coercive treatment, providing ecological evidence that overpathologizing is a repeated problem in professional practice. Study 2 employed an online vignette experiment designed to activate SDO would increase medicalization beliefs and, in turn, overpathologizing tendencies. The manipulation produced no group differences, but medicalization beliefs were positively associated with overpathologizing, and post hoc analyses suggested an indirect pathway from SDO to overpathologizing via medicalization. Together, these findings emphasize overpathologizing as both an empirical reality and a theoretically explicable bias rooted in hierarchy-maintaining ideologies. Positioning clinical judgement within broader dynamics of power and legitimizing discourse, the thesis advances a framework for understanding how institutional authority can subtly translate into client harm, underscoring the ethical imperative for power-aware psychotherapy
Development and Radiation Test of a Secondary Emission Ionization Calorimetry Module
No full textTiras, Emrah/0000-0002-5628-7464; Abubakar, Saleh/0000-0003-1511-2219;The demand for precise, robust, and reliable radiation-resistant particle detectors and ionization calorimeters intensifies due to the escalating luminosity and unprecedented radiation conditions at particle colliders and accelerators. Secondary Emission (SE) Ionization Calorimetry is a novel technology designed to measure the energy of electromagnetic and hadronic particles, particularly in extreme radiation conditions. In this study, we have tested and investigated the development and radiation tests of the novel SE modules. The modules were developed by modifying the conventional Hamamatsu single-anode R7761 Photomultiplier Tubes (PMTs). Three different voltage conditions for the same module were created and the new modules were tested using cosmic and gamma radiation sources, Co-60. The results show that all three modes have good sensitivity to electromagnetic showers, and they are suitable for harsh radiation environments. This study also indicates that the SE module is a promising technology shedding light on future radiation-resistant nuclear and high-energy detectors. Here, we discuss the technical design, test characteristics, and cosmic and particle interaction results of the newly developed SE modules.Scientific Research Projects (BAP) of Erciyes University, Turkiye [FBA-2022-12207, FBG-2022-11499, FDS-2021-11525]; Turkish Academy of Sciences (TUBA)This work was supported by Scientific Research Projects (BAP) of Erciyes University, Turkiye, under the grant contracts of FBA-2022-12207, FBG-2022-11499, and FDS-2021-11525. Dr. Emrah Tiras is thankful for the Turkish Academy of Sciences (TUBA) support under the Outstanding Young Scientists Awards Program (GEBIP) grant. We would like to thank the Office of the Dean for Research for providing the Lab's infrastructure at the ARGEPARK building at Erciyes University. We also would like to thank the Proofreading & Editing Office of the Dean for Research at Erciyes University for this manuscript's copyediting and proofreading service
Test Hızının S2-Cam Elyaf Takviyeli Polimerlerin Düzlem Dışı Mekanik Özelliklerine Etkisi
No full textTest hızları, fiber takviyeli polimerik malzemelerin mekanik tepkisini değiştiren önemli parametrelerdir. Bu çalışma kapsamında, düzlem dışı yükleme koşulu altında farklı test hızları ile S2-cam elyaf takviyeli polimerik malzemelerin eğilme davranışlarını incelenmiştir. Düzlem dışı yükleme koşulu üç noktalı eğilme fikstürüyle sağlanmıştır. 2 mm/dk, 20 mm/dk, 40 mm/dk ve 60 mm/dk olmak üzere dört farklı test hızı bu çalışmada kullanılmıştır. Maksimum yükte sehim miktarı, eğilme modülü ve eğilme mukavemeti test hızına bağlı olarak analiz edilmiştir. Test hızı 2 mm/dk’dan 20 mm/dk ve oradan da 40 mm/dk'ya çıktıkça hem eğilme mukavemetinin hem de eğilme modülünün artış eğilimi gösterdiği bulunmuştur. Bununla birlikte, test hızı 40 mm/dk'dan 60 mm/dk'ya yükseldiğinde eğilme mukavemetinde ve modülde bir düşüş gözlemlenmiştir
Phase-Separated Amorphous Si2BN: A Computational Study
No full textThis study investigates the atomic structure, bonding, and electrical and mechanical properties of amorphous silicon boron nitride (a-Si2BN) using ab initio molecular dynamics simulations. The simulations reveal a distinct phase-separated structure comprising Si-rich and BN-rich domains. BN layers are embedded within the amorphous Si matrix, with only a few bridging atoms linking these regions. The Si-rich region exhibits topological similarities to amorphous silicon, albeit with notable structural distortions. Electronic structure calculations indicate semiconducting behavior with a small bandgap, while mechanical property analysis shows a moderate bulk modulus and Young's modulus, achieving a balance between rigidity and elasticity. These findings position a-Si2BN as a promising material for advanced applications, including flexible electronics, high-temperature semiconductors, and energy storage devices. While the proposed structure is currently hypothetical, its potential experimental realization could open new avenues in material design for emerging technologies.Abdullah Guel UniversityThe author extends gratitude to the Abdullah Guel University Support Foundation for their support. The author acknowledges the computing resources and time generously provided by TUB & Idot;TAK ULAKB & Idot;M High Performance and Grid Computing Center (TRUBA resources)
Optimization of the Recycling Process for Aligned Short Carbon Fiber TuFF Composites
No full textRecycling of carbon fibers enables a sustainable feedstock for industrial applications of high-performance composite materials. This allows light weighting with recycled carbon fibers due to their superior mechanical properties while reducing the high embodied energy and cost of virgin carbon fiber composites. This study optimizes a pyrolysis cycle for fiber recovery of an aerospace-grade thermoset prepreg and a cleaning (oxidation) step to minimize fiber degradation and left-over resin residue, enabling dispersion and alignment of the recycled, discontinuous fibers in the Tailorable Universal Feedstock for Forming alignment process. The study balances the influence of the optimized thermal cycle (pyrolysis + oxidation step) on recycled carbon fiber strength retention with the ability to disperse at the filament level to create aligned, recycled carbon fiber composite samples with high fiber volume fraction. The optimized thermal cycle for efficient fiber recovery applied a pyrolysis step at 500 degrees C for 4 h in an inert gas environment and an additional oxidation step at the same temperature for 100 min. This resulted in similar to 20% strength degradation of the fiber compared to the virgin fiber. The processed recycled composite achieved 44% fiber volume fraction with full modulus translation (similar to 128 GPa) compared to the virgin continuous composite with strength translation (similar to 870 MPa), reaching similar to 50%.Humphreys Engineer Center Support Activity; [W912HQ-P-0075]This material is based upon work supported by the Humphreys Engineer Center Support Activity under Contract No. W912HQ-P-0075. Views, opinions, and/or findings contained in this report are those of the author(s) and should not be construed as an official department of defense position or decision unless so designated by other official documentation
Generating Lost Urban Fabric: Exploring Generative Adversarial Networks as a Tool for Urban Design
No full textBu araştırma, Generative Adversarial Networks'ün (GAN'ler) kaybolan kentsel dokuyu yeniden üretmek için bir tasarım aracı olması potansiyelini incelemektedir. Çalışma, 2023 Kahramanmaraş depremleri nedeniyle büyük yapısal kayıplar yaşayan Hatay şehir merkezine odaklanmaktadır ve kentsel dokuları üretmek için Pix2PixHD mimarisini kullanmaktadır. Araştırma, eğitim veri seti olarak afet öncesi kentsel haritaları kullanarak, Hatay'ın mekânsal sürekliliğini yansıtan kentsel dokular üretmeyi hedeflemektedir. Tez, yarı deneysel ve durum çalışması yaklaşımlarını birleştiren hibrit bir metodoloji benimsemektedir. Çalışma, makine öğrenmesinin temel prensipleri ve kentsel çalışmalardaki önemine değinmektedir, ardından modelin eğitim ve doğrulama süreçlerinin ayrıntılı bir şekilde belgelenmesiyle devam etmektedir. Modelin kentsel dokuları yeniden üretme yeteneğini değerlendirmek için Fréchet Inception Distance (FID) skoru ve üretim çıktılarını görsel gerçeklik ile yapısal bütünlüğü değerlendirmek için Structural Similarity Index Measure (SSIM) gibi nicel metrikler kullanılarak analiz edilmektedir. Ayrıca, veri seti ölçeklerinin (1:2000, 1:3000 ve 1:5000) model performansı üzerindeki etkisi araştırılmaktadır. Bu araştırma, Generative Adversarial Networks'ün afet sonrası kentsel tasarımda bir araç olma potansiyelini ortaya koymakta ve veri seti ölçeğinin gerçekçi kentsel desenler üretmedeki başarısı üzerindeki etkisine dair önemli içgörüler sunmaktadır.This research investigates the potential of Generative Adversarial Networks as a design tool for generating the lost urban fabric. Focusing on the city center of Hatay, Türkiye, which experienced extensive structural loss due to the 2023 Türkiye-Syria earthquakes, the study employs a Pix2PixHD architecture to generate urban patterns. Using pre-disaster maps as the training dataset, the research aims to generate urban patterns that reflect Hatay's architectural identity and spatial continuity. The thesis adopts a hybrid methodology, combining quasi-experimental and case study approaches. It begins with an explanation of the fundamentals of Machine Learning and their relevance to urban studies, followed by detailed documentation of the model training and validation processes. The generated outputs are analyzed using quantitative metrics, including the Fréchet Inception Distance (FID) score to evaluate the model's ability to replicate urban patterns, and the Structural Similarity Index Measure (SSIM) to assess visual realism and structural integrity of the outputs. The study further investigates how different training dataset scales (1:2000, 1:3000, and 1:5000) impact the model's performance. This research demonstrates the potential of GANs as a tool for urban design in a post-disaster context and provides insights into how dataset scale influences the success of the model in generating realistic urban patterns