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Publisher: Elsevier B.V.Scopus Q: Q2

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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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    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
    Citation - Scopus: 6
    A Generalization of the Meir–keeler Type Contraction
    (Elsevier B.V., 2012) Chi,K.P.; Karapinar,E.; Thanh,T.D.
    In this paper, we prove a fixed point theorem which has applications on maps called T-contractions which include a class that satisfies the Meir–Keeler type contractive condition. We also present an example that illustrates that T-contractions are a natural extension of the Meir–Keeler type contraction. © 2012
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    Article
    The Effect of Two Different Types of Daily Disposable Monofocal Contact Lenses on Ocular Wavefront Aberrations
    (Elsevier B.V., 2025) Yakar, K.
    Background: To compare the effect of two daily disposable soft contact lenses on ocular wavefront aberrations. Methods: This study included 34 eyes from 17 patients aged 18 to 40 years (mean age: 27.12±8.3 years) with identical myopic refractive errors in both eyes without astigmatism and requesting contact lens use. Initially, wavefront aberrations; total, tilt, high, total coma, total trefoil, total 4.foil, sphere, high astigmatism, RMS (3 mm/5 mm) were measured using Nidek OPD Scan II aberrometer/topograph in both eyes without contact lenses. Acuvue Oasys with HydraLuxe 1-Day (senofilcon A) daily disposable contact lenses were applied to the right eye, while Precision 1 (verofilcon A) daily disposable contact lenses were applied to the left eye based on refractive errors. Wavefront aberration measurements were repeated 60 min later with contact lenses, and aberrations were compared to baseline and fellow eyes' measurements. The magnitudes of aberration changes after contact lens application were analyzed. Results: Both types of daily disposable contact lenses reduced total wavefront aberrations. Acuvue Oasys with HydraLuxe 1-Day contact lenses showed a significant increase in total trefoil aberration (p = 0.048). Precision 1 contact lenses showed a significant increase (p = 0.034) only in total tilt aberrations compared to baseline. No significant differences were found between the lenses regarding changes in all wavefront aberrations. Conclusion: Both daily disposable lenses effectively reduced total wavefront aberrations, though they increased certain subtypes of high-order aberrations in young adult myopes. © 2025 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC license. http://creativecommons.org/licenses/by-nc/4.0/