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    Conference Object
    Citation - WoS: 5
    Citation - Scopus: 6
    Investigation of the Effects of Axial Ultrasonic Vibrations on Chatter Stability in Milling with Bull Nose Cutters
    (Elsevier Science BV, 2023) Namlu, Ramazan Hakki; Kilic, Zekai Murat; Lorain, Raphael; Kilic, Sadik Engin
    Ultrasonic vibrations-assisted machining has positive effects on the chatter stability and surface integrity of the process. Radial vibration-assisted milling is effective but it needs an advanced control of vibration trajectory hence is not easy to implement. The aim of this paper is to investigate the effects of axial ultrasonic vibrations on stability through disturbing the chip regeneration. A simple way of predicting the stability increase is proposed using missed-cut effect that reduces the effective number of teeth in cut. The axial vibrations are shown to introduce radial runout such that a regular cutter will show the characteristics of a serrated tool. For a 2-tooth bull nose cutter, the proposed method was verified by milling of Ti-6Al-4V material. The results showed that the axial ultrasonic vibrations increased limit axial depth of cut by more than 40%. Therefore, applying axial vibrations would be a simple solution to improve chatter resistance in machining difficult-to-cut materials while avoiding the cost and complexity of serrated rounded edges. The attention on using axial ultrasonic vibrations in milling is increasing, hence further research on modelling the machining dynamics combined with the velocity effects will be needed following this study. (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)
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    Article
    Usability Assessment of Scholarly Publishers' Online Journal Interfaces
    (Springernature, 2023) Peker, Serhat; Dalveren, Gonca Gokce Menekse
    A well-designed and user-friendly online journal interface not only enhances researchers' satisfaction but also bolsters the reputation of academic publishers within the scholarly community. Consequently, the present study undertakes an examination of the usability aspects pertaining to online journal interfaces offered by five prominent academic publishers: Wiley, Sage, Elsevier, Springer, and Taylor & Francis. This investigation encompasses a combination of user testing and post-questionnaire methodologies, aiming to accrue both quantitative and qualitative data concerning user task execution and satisfaction. The research findings spotlight the varying degrees of usability across major academic publishers and emphasize the critical role of design in enhancing researchers' experiences. By identifying both usability strengths and weaknesses, along with offering actionable areas for improvement, this study adds a valuable perspective to the enhancement of academic journal interfaces.
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    Effect of Tool Cavity Conditions on Damping, Chatter Mitigation, and Surface Quality in Internally Cooled Milling Tools
    (Elsevier B.V., 2025) Namlu, R.H.; Dogan, H.; Ozsoy, M.
    Chatter is a critical factor limiting productivity and efficiency in machining processes. Cutting tools significantly impact chatter stability, as they often serve as the most flexible component. The influence of cutting tools on chatter varies depending on their design and cooling mechanisms. Internally cooled cutting tools, commonly used in industrial applications, have the potential to exhibit distinct damping characteristics due to the presence of internal cavities, differentiating them from conventional solid tools. This study explores the effects of internally cooled milling cutting comparing an empty cavity cutting tool with a tool filled with viscous fluid. The primary objective is to evaluate how these conditions influence the damping of the machining system and their subsequent impact on surface quality, a key outcome sensitive to chatter. Surface topography and roughness measurements were taken after the experiments to assess changes in surface quality. The findings offer valuable insights into the role of internal cooling and fluid properties in not only chatter but also vibration suppressions in milling operations, highlighting their potential to enhance machining performance. © 2025 The Author(s).
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    Article
    Synthesis, Photophysical Properties, and Photodynamic Therapy Efficacies of Meso-Pyridine Bodipys and Their Ruthenium Complexes
    (Wiley, 2025) Aksoy, Burcu Topaloglu; Ozcan, Emrah; Bulut, Onur; Kazan, Hasan Huseyin; Cosut, Bunyemin
    Photodynamic therapy (PDT) is a candidate approach for cancer treatment. In PDT applications, a fluorescent molecule, called photosensitizer (PS), induces light-directed production of reactive species, resulting in cytotoxicity. Having tunable fluorescence and easy derivatization properties, the BODIPY core is widely used as a PS. To further increase the light-induced toxicity, studies have shown the conjugation of heavy metals to the BODIPY core. However, such complexes are still needed to fully figure out their potential. In the current study, as part of an ongoing one, two novel ruthenium-BODIPY complexes were synthesized and characterized by structural, photophysical, and biological methods. To obtain complex structures between ruthenium dimers and BODIPY units, [RuCl2(p-cymene)](2) dimers, and non-iodo and di-iodo BODIPY derivatives were reacted in methanol-tetrahydrofuran (THF) medium. Photophysical properties, fluorescence lifetime, molar extinction coefficient, photostability, and capability of singlet oxygen generation were determined using absorption and/or fluorescence spectroscopy. Besides, the structures of the complexes were further clarified by the single-crystal X-ray technique. The cytotoxicity of compounds was examined against the human cervical cancer cell line, HeLa, and breast cancer cell line, MDA-MB-231, both in the dark and by light irradiation. Accordingly, both precursors and their ruthenium complexes were light-dependent toxic; nevertheless, di-iodinated meso-pyridine-substituted BODIPYs displayed light-independent toxicity by long-term treatments. Moreover, the effects of the complexes were cell-specific and the toxicities of di-iodinated BODIPY complexes were inversely correlated with the concentrations, underlying a possible aggregation and/or unpredicted cellular interaction pattern. These results emphasize that further functionalization and molecular characterization of BODIPY-ruthenium complexes are still required for PDT applications.
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    Erratum
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    Citation - WoS: 18
    Citation - Scopus: 23
    An Experimental Study on Surface Quality of Al6061-T6 in Ultrasonic Vibration-Assisted Milling with Minimum Quantity Lubrication
    (Elsevier Science BV, 2022) Namlu, Ramazan Hakki; Yilmaz, Okan Deniz; Lotfisadigh, Bahram; Kilic, S. Engin
    Al6061-T6 is frequently used in the automotive and aerospace industries, where milling is an essential process, due to its high strength-to-weight ratio. In order to achieve improved surface quality in milling, Ultrasonic Vibration-Assisted Milling (UVAM) has been introduced recently. Besides, Minimum Quantity Lubrication (MQL) is another advanced method to enhance the surface properties of the cutting by improving the coolant performance. However, the effects of simultaneous implementation of UVAM and MQL methods has not yet been studied sufficiently. This paper investigates the effects of applying UVAM in tandem with MQL in cutting of Al6061-T6. The results showed that surface quality enhanced with this combination. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)
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    Citation - WoS: 9
    Citation - Scopus: 10
    Multi-Axial Ultrasonic Vibration-Assisted Machining of Inconel 718 Using Al2O3-CuO Hybrid Nanofluid MQL
    (Elsevier Science BV, 2024) Namlu, Ramazan Hakki; Lotfi, Bahram; Kilic, Sadik Engin
    Inconel 718 is a widely used superalloy in the aerospace industry, owing to its exceptional creep and corrosion resistance, as well as its ability to retain strength at elevated temperatures. However, its machinability presents challenges due to its low thermal conductivity and high work hardening rate during conventional machining, resulting in inadequate surface quality. To address this issue, a recent technique known as Ultrasonic Vibration-Assisted Machining (UVAM) has emerged. UVAM involves applying high-frequency, low-amplitude vibrations to the cutting tool or workpiece. Additionally, Minimum Quantity Lubrication (MQL) has been considered as an alternative cooling technique to enhance machining performance. Optimizing the performance of UVAM can be achieved by employing various vibration axes. Additionally, the effectiveness of MQL can be enhanced through the utilization of nanofluids. This study investigates the combined application of multi-axis UVAM and Al2O3-CuO added Hybrid Nanofluid MQL (HNMQL) during the milling of Inconel 718. The evaluation parameters include surface roughness, topography, burr formations, and cutting forces. The results demonstrate that the simultaneous use of multi-axis UVAM and HNMQL significantly improves the machining performance of Inconel 718. This combination leads to better surface quality and overall process efficiency, offering promising prospects for the aerospace industry and other applications involving difficult-to-cut materials. (c) 2024 The Authors. Published by Elsevier B.V.
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    Article
    Citation - Scopus: 8
    Software Product System Model: a Customer-Value Oriented, Adaptable, Devops-Based Product Model
    (Springer, 2022) Altunel, H.; Say, B.
    DevOps pipelines have brought notable advantages, such as fast and frequent software delivery to software production paradigms, but dynamically dealing with quality attributes desired by the customer employing a DevOps pipeline remains a challenge. This work aims to define the design of a systems thinking inspired model, called Software Product System Model (SPSM), applying a customer-value oriented, holistic approach for implementing quality requirements, and its application and evaluation in a large software house. The main features include dynamic control of quality gates, the parameters of which are driven by customer requirements and feedback from surveys. All of the inputs are collected in a product backlog and fed forward to the quality gates over the DevOps pipeline. SPSM was successfully deployed in a large software house extending a DevOps pipeline with an accompanying improvement of customer-value oriented key performance indicators for projects. In a 2-year-long case study, security and code quality were the main quality attributes, with the metrics on security vulnerabilities and unit test coverage. At the end of the 2020, the DevOps pipeline within SPSM provided a 69.50% decrease of security vulnerabilities of all software products, and a 29.43% increase in unit test coverage for the whole code base for increasing code quality. At the end of 2020, the project completion ratio was measured to be 99.50% and the Schedule Performance Index (SPI) was measured to be 99.78% as the average of 762 projects delivered. The flexibility of SPSM allowed the software house to adapt to changing customer expectations. A checklist is provided for the replicability of the model application. © The Author(s), under exclusive licence to Springer Nature Singapore Pte Ltd 2021.
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    Citation - Scopus: 1
    Enhancing Sustainable Machining of Inconel 718 Using Multi-Walled Carbon Nanotubes and TiO2based Nanofluid Minimum Quantity Lubrication
    (Elsevier B.V., 2025) Namlu, Ramazan Hakkı; Kaftanoĝlu, Bılgın
    Inconel 718 is extensively utilized especially in the aerospace sector due to its outstanding resistance to creep and corrosion, along with its capability to maintain strength at high temperatures. However, its high work hardening rate and low thermal conductivity present significant challenges in machining processes, including the need for extensive use of coolants, shortened tool life, and the necessity for post-processing operations for adequate surface quality, all of which hinder sustainable manufacturing. To address these issues, an innovative cooling/lubrication method, Nanofluid Minimum Quantity Lubrication (NMQL), aims to enhance the sustainable machining of Inconel 718 by minimizing these problems. NMQL involves the aerosolized delivery of nanoparticle-enriched nanofluid oil with compressed air to the cutting zone. In this way, NMQL utilizes the nanoparticles' cooling and lubrication abilities, resulting in lower cutting forces, reduced surface roughness, and decreased tool wear compared to other cooling/lubrication conditions, thereby improving machining performance. This study compares the performance of NMQL in terms of cutting forces, surface roughness and topography, and subsurface microhardness, using Multi-Walled Carbon Nanotubes (MWCNT) and TiO2nanoparticles, with Conventional Cutting Fluids (CCF), aiming to achieve more sustainable machining of Inconel 718. Also, a sustainability assessment was done using Pugh Matrix Approach in order to find the most sustainable cooling option. © 2025 Elsevier B.V., All rights reserved.
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    Article
    Basin Evolution in the Gulf of Çandarlı Through Seismic Mapping, Aegean Sea, Offshore Türkiye
    (Springer Nature, 2025) Kılıç, B.O.; Uluğ, A.; Aydemir, A.
    Early Miocene lacustrine deposits possessing source rock and reservoir properties are characterised by seismic mapping in the Foça-Çandarlı Basin of the Turkish sector of the Aegean Sea. A similar petroleum system has also been recognised in the adjacent onshore Gediz and Bakırçay grabens. In this study, 800 km of seismic data acquired in 1975 and 1985 have been interpreted. Miocene and Pliocene horizons were mapped, and possible hydrocarbon traps were identified. In this context, the tectonic evolution of the Foça-Çandarlı Basin has been determined. The Foça-Çandarlı Basin opened under NE and SE extension during the Late Oligocene to Early Miocene. The tectonic regime shifted to a transpressional state due to the westward tectonic escape of Anatolia during its collision with the Aegean Block. As a consequence of this tectonic reversal, we observe a clockwise rotation in the compressional deformation along the southern margin of the basin. In contrast, the change may have involved a counterclockwise rotation in the north since the end of the Early Miocene. Faults at the basin boundaries were inverted, and the basin began to close from the west during the Mid-Late Miocene and Pliocene. The seismic mapping accurately demonstrates all these changes. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.