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Bruggemann Teorisi Temelli Metal ve Polimer Melez Izgaralarının Optik Polarizasyon Tepkisi
No full textMevcut literatürde ızgara tasarımlarının farklı metaller ve polimerler içeren kompozisyonları yeterince ele alınmamıştır. Çalışmamız, değişen malzeme kompozisyonlarının polarizasyon özellikleri üzerindeki etkisini araştırarak bu boşluğu doldurmayı amaçlamaktadır. Bu sorunu ele almak için, Bruggeman Teorisi'ni kullanarak altın, gümüş ve poli(dimetil siloksan) (PDMS) karışımlarının kırılma indisleri hesaplanmış, bu melez malzemelerden yapılan ızgaraların optik geçirgenliği ve yansıması simüle edilmiştir. Analizimiz, çeşitli malzeme oranları için farklı dalga boylarında polarizasyon oranında belirgin tepe noktaları ortaya koymuştur. Özellikle, simülasyon sonuçlarımız, polarizasyon oranının 450-1000 nm aralığında ayarlanması potansiyelini göstermektedir. Dahası, simülasyon ortamında hem 0 hem de 1 polarizasyon oranlarına ulaşılabildiği gösterilmiştir. Bu sonuçlar, belirli dalga boylarını hedefleyen optik filtreler ve polarizörler tasarlanmasına olanak sağlayacaktır
Development of Buckwheat Starch-Capric Acid Complex-Based Film: Process Optimization and Film Characterization
No full textTo overcome the limitations of starch usage alone, the film formation ability of the buckwheat starch-capric acid complex (BS-CA) was optimized, and the films were characterized. Significant models were obtained for tensile strength (TS) and Young's modulus (YM) of BS-CA film (p < 0.0001). The glycerol/starch ratio, temperature, and their interactions were significant in the YM model (R-2 is 0.9851). The BS-CA film had a better water vapor barrier (0.463 +/- 0.02 g mm/m(2) h kPa), with lower water solubility (WS) (34.18 +/- 1.70%) and moisture content (MC) (16.87 +/- 0.09%) than the buckwheat starch (BS) film (p < 0.05). It had lower thickness (0.073 +/- 0.00 mm) and TS (0.624 +/- 0.04 MPa) but higher elasticity (114.60 +/- 3.12%). The non-covalent interactions were determined between BS and CA, since new peaks were not observed in the film's FTIR spectrum. BS-CA film had a typical V-type crystalline structure and had slightly lower decomposition temperatures than the BS film. Contact angle measurements (55.19 degrees +/- 1.7), and images of AFM topography and SEM showed that the BS-CA film surface was hydrophilic; height and average roughness values were 1014 and 276 nm, respectively, which were quite higher than those of BS film. The results reveal that starch modification with fatty acid is a promising way to develop starch-based films to be used in practical applications.Turkish Scientific and Technological Research Council (TUBITAK); [119O031]The authors would like to acknowledge the financial support of the Turkish Scientific and Technological Research Council (TUBITAK) (Project Number: 119O031)
Investigating Strain Rate Effects on Damage Mechanisms in Hybrid Laminated Composites Using Acoustic Emission
No full textDemirbas, Munise Didem/0000-0001-8043-6813; Caliskan, Umut/0000-0002-8043-2799; Zafar, Hafiz Muhammad Numan/0000-0001-7122-4974;Hybrid composites, which combine distinct fiber types such as carbon, basalt, and aramid, provide a synergistic balance of strength, stiffness, impact resistance, and energy dissipation, making them appealing for critical applications in aerospace, automotive, and other high-performance industries. Monitoring damage progression in these composites is vital for ensuring structural integrity and preventing catastrophic failures. Acoustic emission (AE) serves as a powerful, noninvasive technique for real-time structural health monitoring, capturing the transient stress waves generated when damage events occur. This study utilizes AE to examine the influence of strain rate on damage modes in carbon/basalt/aramid hybrid composites under three-point bending. An unsupervised feature selection based on Laplacian scores is employed to identify the most relevant AE features with damage modes, while SHapley Additive Explanations (SHAP) are used to evaluate the correlation between AE features and strain rates. The correlation analysis results indicate that peak frequency (PF) serves as a key indicator, demonstrating significant shifts at higher strain rates. Gaussian Mixture Model (GMM) clustering is used to analyze hybrid composites by examining clustered AE signals based on selected features identified through Laplacian scores, with Silhouette scores employed to determine the optimal number of clusters. This study highlights the role of AE in understanding fiber interactions and damage evolution, offering valuable insights into the mechanical performance and optimization of carbon/basalt/aramid hybrid composite structures
Stress and Damage Distribution Analysis of Steel Reinforced Geopolymer Concrete Beams: Finite Element Method and Experimental Comparison Under Varying Design Parameters
No full textOzbayrak, Ahmet/0000-0002-8091-4990; Kucukgoncu, Hurmet/0000-0001-5148-8753;Geopolymer concrete (GPC) is a sustainable and eco-friendly alternative to ordinary Portland cement-based concrete (OPC). However, its application in reinforced concrete structures remains limited due to insufficient research on structural performance. This study examines the effects of tensile reinforcement ratio, sodium silicate/sodium hydroxide ratio, and curing method on GPCreinforced concrete (GPC-RC) beams. Experimental and numerical bending tests were performed on GPC and OPC beams with similar tensile reinforcement and strength properties. Load- displacement and moment-curvature relationships were obtained and compared, while stress and stiffness behaviors were analyzed numerically. The results show that curing methods and reinforcement ratios significantly influence GPC beam behavior. In GPC samples, numerical and experimental displacement and load values differed by approximately 10 % at both yield and ultimate points. For OPC, these differences were 35 % and 14 % at the yield point and 17 % and 25 % at the ultimate point. GPC exhibited distinct stress and damage distribution characteristics compared to OPC. The finite element models were statistically validated, confirming their consistency with experimental results. These findings contribute to the understanding of GPC's structural behavior and provide guidance for its design and optimization in reinforced concrete applications.TUBITAK (The Scientific and Technological Research Council of Turkiye) [121M236]This research was supported by TUBITAK (The Scientific and Technological Research Council of Turkiye) under grant number 121M236
Effect of Yttrium/Lanthanum-Doped Ultrasonically Assisted Nano-Hydroxyapatite on Remineralization and Bracket Bond Strength in Artificial Enamel Lesions
No full textBackground This in vitro study aimed to evaluate the remineralization efficacy of ultrasonically assisted yttrium fluoride-doped (Ult-YF3-nHAP) and lanthanum fluoride-doped (Ult-LaF3-nHAP) nano-hydroxyapatite (nHAP) on artificially induced enamel lesions (aWSLs), and to compare their performance with acidulated phosphate fluoride (APF) gel, fluoride varnish, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and resin infiltrant (ICON). Methods This in vitro study followed a four-phase design: enamel lesion creation, application of remineralization agents, a 14-day treatment protocol, and post-treatment analyses using QLF, Micro-CT, SEM-EDX, and SBS testing. This study included 168 extracted human premolars, divided into eight experimental groups (n = 21 per group): (1) Demineralized control (no remineralization treatment), (2) Acidulated phosphate fluoride (APF) gel, (3) Fluoride varnish, (4) Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), (5) Ultrasonically assisted nHAP (Control nHAP), (6) Ult-YF3-nHAP, (7) Ult-LaF3-nHAP, and (8) Resin infiltrant (ICON). The aWSLs were created under laboratory conditions. Brackets were bonded to the teeth with composite material, and aWSLs were created under laboratory conditions. After lesion formation and at the end of the experimental process, micro-computed tomography (Micro-CT) and laser-assisted quantitative light fluorescence (QLF) analysis were performed to assess lesion progression and remineralization. Additionally, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and shear bond strength (SBS) tests were conducted at the end of the study. Statistical analysis was performed using one-way ANOVA, Kruskal-Wallis, and Mann-Whitney U tests, with a significance level of p < 0.05. Results The bracket bond strength test data showed no significant differences between the groups (p = 0.156). Significant differences were found among groups for QLF fluorescence recovery (Delta F, p < 0.001), with the Ult-YF3-nHAP group showing the greatest increase (median: +0.5, IQR: -1.4 to + 0.7), while the control group showed the greatest decrease (median: -12.1, IQR: -12.4 to -10.2). Micro-CT analysis also revealed significant differences between groups (p = 0.008). The APF Gel group showed values comparable to those of all other experimental groups. The highest remineralization values were recorded in the Ult-YF3-nHAP group (6.87 +/- 3.03 mm(3)), whereas the lowest values were found in the Varnish group. The demineralized control group had significantly higher values than the Varnish group, but lower than the Ult-LaF3-nHAP group. SEM-EDX analysis revealed that fluoride weight was significantly lower in the Tooth Mousse and Varnish groups compared to the other experimental groups (p < 0.001). Ca/P ratio was significantly lower in the demineralized control, Varnish, and Ult-YF3-nHAP groups than in other experimental groups (p = 0.002). Conclusion Ult-YF3-nHAP showed higher efficacy in remineralization of aWSLs compared to fluoride-based treatments, CPP-ACP, and resin infiltrant. The highest remineralization was detected in the Ult-YF3-nHAP group by micro-CT and QLF analysis, while fluoride varnish gave the lowest result.Bilimsel Arastirma Projeleri, Erciyes niversitesiWe would like to thank the Proofreading & Editing Office of the Dean for Research at Erciyes University for the copyediting and proofreading service for this manuscript
Quenchable Amorphous Diamond: A Novel High-Pressure Route to Tetrahedral Amorphous Carbon
No full textThis study presents a groundbreaking theoretical prediction: the high-pressure transformation of amorphous graphite into a high-fraction sp3-bonded amorphous diamond phase. Employing ab initio molecular dynamics simulations, it is demonstrated that under extreme pressures, amorphous graphite undergoes an irreversible transition to an amorphous diamond phase. Thermodynamic analysis confirms the first-order nature of this sp2-to-sp3 transformation, with the transition predicted to occur at approximate to 33 GPa under experimental conditions. This transformation offers a novel pathway toward the synthesis of amorphous carbon with a high fraction of sp3 bonding, a long-standing challenge in materials science. This work expands understanding of carbon's high-pressure behavior and provides a compelling theoretical foundation for future experimental investigations aimed at synthesizing and characterizing this novel material.Abdullah Gul University Support FoundationThe author sincerely thanks Prof. David Drabold and his research group for providing their a-GC models. Additionally, the author expresses gratitude to the Abdullah Gul University Support Foundation for their support. The computing resources and time generously provided by TUB & Idot;TAK ULAKB & Idot;M High Performance and Grid Computing Center (TRUBA) are also gratefully acknowledged
Efficient Relative Localization and Coordination System for Unmanned Ground Vehicle Formations Under Directed Graph Structure
No full textOnboard localization for multi-robot systems stands as a critical area of research with wide-ranging applications. This paper introduces an innovative framework for multi-robot localization, uniquely characterized by its onboard capability, thereby negating the dependency on external infrastructure. Our approach harnesses the inherent capabilities of each robot, enabling them to localize and synchronize their movements independently. The integration of cooperative localization algorithms with formation control mechanisms empowers a group of robots to sustain a predefined formation while following a linear trajectory. The efficacy of our framework is substantiated through comprehensive simulations and real-world experimental validations. We rigorously assess the system's resilience to localization inaccuracies and external disturbances, demonstrating its adaptability and consistency in maintaining formation under diverse conditions. Furthermore, we explore the scalability of our approach, highlighting its potential to manage varying numbers of robots and its applicability in tasks such as collaborative transportation.TUBITAK [118C348]This work was supported by the 2232 International Fellowship for Outstanding Researchers Programme of TUBITAK (Grant No: 118C348
Optimal Decision-Making for Operations of Smart Grids and Microgrids
No full textYenilenebilir enerji kaynaklarının artan entegrasyonu ve elektrik üretiminin merkeziyetsizleşerek dağıtık hale gelmesi, güç sistemlerinde koordinasyon ve sistem güvenilirliği açısından önemli zorlukları beraberinde getirmiştir. Bu çalışma, akıllı enerji toplulukları için, olasılıksal modelleme, merkezî optimizasyon ve uyarlanabilir kontrol yaklaşımlarını bir araya getiren çok katmanlı bir metodolojik çerçeve sunmaktadır. İlk aşamada, meteorolojik değişkenler arasındaki karmaşık doğrusal olmayan ilişkileri modelleyebilen ve rüzgâr enerjisi potansiyelini belirsizlik altında değerlendirebilen, kopula teorisi, derin öğrenme ve karar ağaçlarını birleştiren hibrit bir yöntem geliştirilmiştir. İkinci aşamada, farklı hane yapılarını içeren bir şebekede, dağıtık enerji kaynaklarının zamanlaması ve eşler arası (P2P) enerji ticaretinin optimizasyonu için Karışık Tamsayılı Doğrusal Programlama (MILP) tabanlı model tasarlanmıştır. Son aşamada ise, kural tabanlı karar verme yapısı, Derin Deterministik Politika Gradyanı (DDPG) algoritması ile geliştirilerek, gerçek zamanlı fiyatlandırma ve merkezsiz karar alma yeteneklerine sahip bir operasyonel kontrol ortamı oluşturulmuştur. Geliştirilen model, değişken sistem koşullarına uyum sağlamakta, enerji yönetimini optimize etmekte ve belirsizlik altında uzun vadeli sistem performansını artırmaktadır. Bu çalışma, enerji sistemlerinde kaynak değerlendirmesinden operasyonel kontrole uzanan; deterministik planlamayı gerçek zamanlı, öğrenen yapılarla bütünleştiren kapsamlı bir karar destek mimarisi sunmaktadır. Elde edilen bulgular, dağıtık yenilenebilir kaynakların entegrasyonunu destekleyen, esnek, dayanıklı ve sürdürülebilir enerji sistemlerinin geliştirilmesine katkı sunmaktadır.The rising adoption of renewable energy sources and decentralized electricity production has introduced new challenges in power system coordination, uncertainty management, and reliability. This study presents a multi-stage framework combining probabilistic modelling, centralized optimization, and adaptive control for smart energy communities. First, a hybrid model integrating copula theory, deep learning, and decision trees is developed for probabilistic wind energy assessment. Second, a Mixed-Integer Linear Programming (MILP) model is formulated to optimize distributed energy resource scheduling and peer-to-peer (P2P) energy trading across various household types. Finally, a rule-based control environment is extended with a Deep Deterministic Policy Gradient (DDPG) reinforcement learning algorithm to enable real-time pricing and decentralized decision-making. The proposed model adapts to dynamic conditions, optimizes energy dispatch, and improves long-term system performance under uncertainty. Collectively, this study introduces an integrated paradigm that combines resource evaluation, system optimization, and adaptive control. The findings highlight the potential for intelligent energy management to enhance grid flexibility, encourage decentralized operation, and facilitate the transition towards sustainable and resilient power systems
Evaluation of Diatomite Substitute With Thermal Power Plant Waste Fly Ash in Sustainable Geopolymer Through Life Cycle Assessment
No full textDurak, Ugur/0000-0003-2731-3886;This research demonstrates the potential of diatomite as a fly ash replacement to improve mechanical properties and environmental sustainability and presents it as a viable alternative for sustainable construction. Additionally, a life cycle assessment (LCA) was conducted on the produced mortars to quantitatively compare their environmental impacts using a cradle-to-gate approach. In mixtures, it was used by replacing the diatomite in the ratios of 1%, 2%, 3%, 4%, and 5% by weight of the fly ash. Workability, unit weight, flexural and compressive strength, abrasion resistance, elevated temperature resistance and microstructure analysis were carried out. The results indicated that replacing 1%, 2%, and 3% diatomite increased the compressive and flexural strength of mortars due to their higher specific surface area. Two percent replacement of diatomite provided the best results. FESEM results of 3% diatomite inclusion showed more intense and compact microstructure of geopolymer. Diatomite inclusion increased the abrasion resistance of geopolymer. Since 2% diatomite replacement was found to be optimum, the LCA results showed that geopolymer mortar with 2% diatomite has 25% lower impacts in terms of global warming potential and 10% lower impacts in terms of terrestrial ecotoxicity than conventional Portland cement mortar.Bilimsel Arascedil;timath;rma Projeleri, Erciyes niversitesiWe would like to thank the Proofreading & Editing Office of the Dean for Research at Erciyes University for the copyediting and proofreading service for this manuscript
The Impact of Consumers' Motives for Watching Unboxing Videos on eWOM and Purchase Intentions: The Mediating Role of Ad Involvement
No full textOzer, Serhat/0000-0001-7626-6487;With the rise of social media and influencer marketing, unboxing videos have become key for connecting with customers. Drawing on the Uses and Gratifications Theory (UGT) and Elaboration Likelihood Model (ELM), this study examines how motives for watching unboxing videos influence consumers' purchase and eWOM intentions, and the mediating role of ad involvement. Analyzing survey data from 499 YouTube viewers, the research finds that information-seeking, entertainment, and interpersonal utility motives significantly affect purchase and eWOM intentions, while pass-time motives do not. The study contributes a novel UGT-ELM-based model with consumer-focused insights and discusses its theoretical and practical implications. The study also offers implications for marketing analytics