Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Comparative Analysis of Modulation Shapes on Laser Diode Performance with a High-Efficiency LLC Resonant Converter Driver(Wiley, 2026-02-06) Yigit, Hayri; Rifat boynuegri, Ali; Tekgun, Burak; Rifat Boynuegri, AliHigh-power laser diodes (LDs) are key components in laser-based wireless power transfer (WPT) systems, where end-to-end efficiency is one of the most critical performance metrics. This study investigates the driving performance of an LD powered by a high-efficiency LLC resonant converter under three distinct excitation waveforms-sinusoidal, triangular, and rectified-sine-using a MATLAB/SIMULINK model and an experimental setup designed to reproduce real-world operating conditions. Each waveform is synthesized through frequency modulation of a full-bridge inverter stage and filtered at the output. The analysis examines the impact of modulation shape on output current ripple, converter efficiency, and overall LD efficiency. Experimental validation confirms the simulation trends, underscoring the trade-offs between waveform smoothness, implementation complexity, and efficiency. Beyond confirming that constant-current operation yields the highest LD efficiency, this study explicitly quantifies how low-frequency current ripple induced by different modulation waveforms propagates through the LLC resonant converter, alters RMS current stress, and translates into measurable efficiency degradation at both the driver and LD levels. By experimentally correlating waveform symmetry, ripple magnitude, and loss mechanisms, the work establishes practical design boundaries for waveform-modulated laser drivers in WPT systems.Article Looking for Stability in Chaos: A Scoping Review of Relational Turbulence Theory from a Dyadic Perspective(Wiley, 2025-11-21) Lagap, Adar Cem; Gungor, DuyguThe current scoping review overviews articles that apply the relational turbulence model/theory to guide the implementation of actor-partner interdependence modeling within a structural equation modeling framework. Sixteen studies are examined in the final synthesis of the review. Research themes center on communication strategies and social connection, dispositional and situational factors, and, lastly, mental and physical health. Current work illustrates that scholars are primarily interested in sources of relational uncertainty and its intrapersonal and interpersonal consequences. Sources of partner influence and their implications for relational dynamics are also examined across the synthesized studies. Overall, more actor effects than partner effects were statistically significant. Commercial statistical programs appear preferred for analyzing dyadic data, and assessments of fit indices are reported to evaluate proposed analytic models in this body of research. Methodological and theoretical limitations are highlighted, and implications for future research are discussed.Article Citation - WoS: 1A Comprehensive Analysis of Acoustic Emission Signals To Distinguish the Different Damage Types for Fiber-Reinforced Polymers: A Review(Wiley, 2025-12-03) Yilmaz, CagatayFiber-reinforced polymers (FRP) attract the attention of key industries, such as aerospace, wind energy, and automotive, as they can reduce the weight of structural components without compromising their mechanical properties. Due to FRP's anisotropic and non-homogeneous structure, their failure under different loading conditions and the corresponding failure mechanisms must be investigated. One method that progressively monitors the failure of FRP underload is Acoustic Emission (AE). AE can register the elastic stress waves in the form of digitized waveforms, released by the discontinuous events that occur in the FRP under load. These discontinuities can be clustered and identified as transverse cracking, fiber/matrix interface debonding, delamination, and fiber failure by analyzing the AE waveforms. Recently, numerous clustering approaches using machine learning algorithms, along with the varying features of AE waveforms, have been developed and are being used. These algorithms include supervised and unsupervised clustering, deep learning algorithms, and neural network methods, among others. While supervised algorithms require a training dataset to classify AE signals, unsupervised algorithms can perform clustering without training datasets. Deep learning and neural network algorithms can train themselves to cluster data, but they may require a significant amount of computer power when the dataset is large. This review paper provides comprehensive information on the clustering algorithm, along with the AE wave features, the range of features for different damage types, and the type of reinforcer.Article Citation - WoS: 1Citation - Scopus: 1A Comprehensive Review on the Extraction and Recovery of Lithium from Primary and Secondary Sources: Advances Toward Battery-Grade Materials(Wiley, 2025-10-20) Top, Soner; Kursunoglu, Sait; Altiner, MahmutLithium-ion battery (LIB) technologies have become indispensable to modern energy systems, driving global demand for high-purity lithium compounds. This review focuses on lithium recovery and purification strategies for battery-grade lithium carbonate (Li2CO3) and lithium hydroxide (LiOH), addressing both primary sources (brines and minerals) and secondary sources (waste materials). Industrially established processes, such as evaporation-based brine treatment and conventional metallurgical methods, are discussed alongside emerging techniques, including membrane separation, solvent extraction, and CO2-assisted precipitation. Particular attention is given to lithium precipitation mechanisms, the behaviour of co-existing ions during extraction, and the specific quality requirements for cathode material synthesis. By evaluating process scalability, environmental impact, and product purity, this review provides a comprehensive understanding of current practices and future directions. Additionally, it highlights the growing importance of lithium in the context of accelerating electric vehicle (EV) adoption, underscoring the bright and expanding future of the lithium industry.Article Citation - WoS: 1Citation - Scopus: 1Unhappiness Among the Unemployed: The Roles of Descriptive Norms, Injunctive Norms and Personal Beliefs(Wiley, 2025-05-19) Ugur, Zeynep B.; Durak, AysenurThis study explores the influence of social norms and individual beliefs on the well-being of unemployed individuals in Turkey, a context marked by both chronic unemployment and a high societal valuation of employment. Using province-level representative data from the 2013 Life Satisfaction Survey, encompassing 196,203 observations, we analyse how descriptive norms (prevalence of unemployment) and injunctive norms (social pressures due to unemployment) at the province level affect the happiness of the unemployed. We utilized people's perception of employment for being respected in social life and personally feeling social pressure as a measure of individual beliefs. Multilevel regression results reveal that descriptive norms can modestly alleviate the adverse impact of unemployment, particularly for the short-term unemployed, while injunctive norms slightly intensify the unhappiness of being unemployed, especially in the short term. The unemployed's personal beliefs about the value of employment matter for their happiness. These findings underscore the theoretical implications of social norms in shaping the well-being of the unemployed and highlight the importance of individual beliefs in moderating these effects.Article Citation - WoS: 6Citation - Scopus: 6Uncovering Nanoclusters in Amorphous AlN: An Ab Initio Study(Wiley, 2014-12-22) Durandurdu, MuratAmorphous AlN (a-AlN) is modeled by melt-and-quench technique using ab initio molecular dynamic simulations. For the first time, three-dimensional hexagonal-like nanoclusters embedded in amorphous matrix are proposed for a-AlN. The model is chemically ordered and dominantly fourfold coordinated, but its short-range order is partially different from the crystalline morphology due to the nanoclusters. The model is semiconducting with a theoretical band gap of 1.7eV.Article Citation - WoS: 6Citation - Scopus: 6Two Successive Amorphous-to Phase Transformations in TiO2(Wiley, 2017-05-22) Durandurdu, MuratBased on constant pressure ab initio simulations, we propose, for the first time, two successive amorphous-to-amorphous phase transformations for TiO2. The first one is a gradual phase transformation from a low-density amorphous phase to a high-density amorphous phase, whereas the second one is a first-order phase transformation from the high-density amorphous phase to a very high-density amorphous phase. The low-density amorphous to high-density amorphous phase change is irreversible, whereas the high-density amorphous to very high-density amorphous phase transformation is reversible. The high-density amorphous and very high-density amorphous phases consist of differently coordinated configurations. The sevenfold and ninefold-coordinated arrangements formed in amorphous TiO2 under pressure are similar to the main building motif of the baddeleyite and cotunnite polymorphs of TiO2, respectively, while the eightfold-coordinated configuration is different from the local structure of the cubic TiO2 phase. The electronic structure calculations suggest that both dense amorphous phases present a semiconducting character with a band gap energy less than that of the original low-density amorphous phase.Article Citation - WoS: 4Citation - Scopus: 6Traffic Aware Cyclic Sleep-Based Power Consumption Model for a Passive Optical Network(Wiley, 2022-02-28) Butt, Rizwan Aslam; Faheem, Muhammad; Anwar, Muhammad; Mohammadani, Khalid H.; Idrus, Sevia M.For a network, a power consumption model is an important tool to test the performance of a network process for different traffic loads. In a Passive optical network (PON), the optical network unit (ONU) is responsible for the major power consumption of PON. Both IEEE and ITU have standardized a cyclic sleep process (CSP) for ONU energy conservation. In next-generation PON; TWDM and XGS PON, the ONU power contribution has increased further due to higher number of ONUs and ONU being tunable. Therefore, an accurate power consumption model of the CSP process for energy efficiency studies under different traffic conditions is of prime importance. The existing CSP power consumption models do not depict the CSP process accurately especially the inactivity of the ONU in the asleep and sleep aware states are not taken into account which reduce the accuracy of the model. The proposed inactivity aware model (IAM) overcomes these gaps and very accurately models the CSP process, as evident from the results, which are better than earlier model results and quite close to earlier published simulation results. The model is also validated through a simulation-based study and the simulation results are observed to be very close to the model results with only a 5% deviation.Article Citation - WoS: 1Citation - Scopus: 1The Rise of Digital Responsibility: Insights From Türkiye's Banking and E-Commerce Sectors(Wiley, 2025-07-28) Aydogdu, Ceyda Cihan; Karsak, Banu Mujde Baskan; Baskan Karsak, Banu Mujde; Cihan Aydogdu, CeydaThis study examines how the concept of corporate digital responsibility (CDR) principles, such as data security, transparency, and digital inclusivity, is integrated into the corporate structures of the banking and e-commerce sectors in T & uuml;rkiye. The objective is to identify sector-specific key trends, challenges, and strategic approaches related to the adoption of CDR in corporate frameworks. By presenting a comparative analysis of two critical sectors, this research highlights the sectoral differences in understanding and implementing CDR. Employing a qualitative methodology, the research utilizes semi-structured interviews with senior executives, corporate communication directors, IT professionals, and legal experts. The interviews were thematically analyzed and digitized using Python-based coding tools to enhance analytical consistency and depth. The findings indicate that the banking sector demonstrates greater maturity in CDR awareness and an institutionalized approach to CDR, particularly in areas related to data security and regulatory compliance. Conversely, the e-commerce sector shows slower and more fragmented progress, lagging in the adoption and implementation of CDR principles. Both sectors require significant improvements to align with global CDR standards. The study also underlines the importance of cross-sector collaboration, government enforcement mechanisms, and user-driven demands in fostering responsible digital ecosystems. Future studies should employ quantitative methods to evaluate the regulatory and cultural influences on digital responsibility. Furthermore, research that focuses on consumer perspectives, the long-term development of regulatory compliance, and compares different emerging economies will help broaden the current literature on CDR.Article Citation - WoS: 6Citation - Scopus: 6Tetrahedral Amorphous Boron Nitride: A Hard Material(Wiley, 2019-09-25) Durandurdu, MuratWe generate a tetrahedrally coordinated amorphous boron nitride (BN) model by means of first principles molecular dynamics calculations and report its mechanical and electrical properties in detail. The amorphous configuration is almost free from chemical disorder and consists of about 20% coordination defects, similar to tetrahedral (diamond-like) amorphous carbon. Its theoretical band gap energy is about 2.0 eV, less than 4.85 eV estimated for cubic BN. The bulk modulus and Vickers hardness of tetrahedral amorphous BN are computed as 206 GPa and 28-35 GPa, respectively. Based on these findings, we propose that tetrahedral noncrystalline BN can serve as electronic and hard materials as well.