Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Comprehensive 4E Analysis, Multi-Objective Optimization, and Feasibility Study of Five Natural Gas Liquefaction Processes With a Case Study for Iran(Elsevier Sci Ltd, 2026) Basmenj, Farhad Rahmdel; Tabriz, Zahra Hajimohammadi; Aghdasinia, Hassan; Mohammadpourfard, MousaNatural gas (NG) is increasingly vital as a cleaner energy source due to its lower carbon emissions compared to other fossil fuels. Liquefaction facilitates efficient long-distance transportation. While numerous studies address NG liquefaction's technical aspects, holistic research remains limited. This study presents a comprehensive evaluation of five conventional natural gas (NG) liquefaction processes (including SMR-Linde, SMR-APCI, C3MRLinde, DMR-APCI, and MFC-Linde) through a 4E framework: energy, exergy, exergoeconomic, and exergoenvironmental analyses. Addressing limitations in prior research, it incorporates environmental considerations and introduces production volume-independent metrics to ensure equitable comparisons. Multi-objective optimization, based on exergoeconomic and exergoenvironmental criteria, is employed to identify Pareto-optimal operating conditions. To accelerate this complex process, neural networks are utilized. The study concludes with a feasibility assessment of large-scale LNG production in Iran, offering practical insights for optimizing process selection and enhancing the economic and environmental viability of LNG technologies. Simulations show that the MFC-Linde cycle as the most efficient regarding specific energy consumption (0.2563 kWh/kgLNG), coefficient of performance (3.184), and exergy efficiency (52.32 %). It also demonstrates the lowest unit exergy cost (3.67$/GJ) and exergy unit environmental impact (5271.86mPts/GJ). Multi-objective optimization, considering both exergetic-economic and exergetic-environmental criteria, using neural networks and genetic algorithms in MATLAB identifies Pareto-optimal conditions for all processes. For the MFCLinde, as the most efficient process, optimal operating conditions in the exergetic-economic trade off scenario are: Exergy efficiency of process = 51.45% and Exergy cost rate of LNG = 82, 162.15$/h; at Pressure of NG feed = 5, 925.32kPa, Pressure drop in valve = 5, 831.99kPa, and NG side temperature in heat exchanger = -168.34 degrees C. Finally, a feasibility study for large-scale LNG (Liquefied Natural Gas) production in Iran shows promising results, with a return on investment of 32.24 %/year and a payback period of 2.34 years, indicating the project's potential success in regions with abundant NG reserves.Article Enhanced Wear Resistance of Epoxy Composites Through the Incorporation of Diatom Frustules: a Multi-Objective Optimization Approach(Springer Heidelberg, 2025) Gulturk, E.; Aydin, L.; Sahin, A. E.; Sinmazcelik, T.; Guden, M.The present work investigates the enhancement of wear resistance in epoxy composites through the incorporation of calcined and natural diatom frustules (CDFs and NDFs) as reinforcing fillers. The CDFs, pre-calcined at 1200 degrees C during manufacturing to improve structural integrity and eliminate organic matter, were supplied in processed form. Both CDFs and NDFs were subsequently wet-sieved (below 325 mesh) and dried at 120 degrees C for 2 h to ensure particle uniformity and moisture removal. Epoxy composites were prepared with 5-20 wt% frustule content. The fillers were ultrasonically dispersed in the epoxy matrix to improve uniformity and reduce agglomeration, followed by vacuum degassing and thermal curing. Wear performance was initially evaluated for all samples at a fixed 1000-cycle duration. Based on preliminary results, composites with 15 wt% and 20 wt% filler content which showed the highest wear resistance, were further tested under varying sliding distances corresponding to 300-1000 cycles to examine long-term behavior. Tests were conducted under dry sliding conditions using a block-on-ring tribometer at 50 N load. Using a systematic modeling-design-optimization framework, the study defines diatom weight fraction, sliding test duration, and frustule type as design variables. The experimental process was modeled through multiple nonlinear neuro-regression analyses, selecting the most realistic model based on Rtraining2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R_{{{\text{training}}}}<^>{2}$$\end{document}, Rtesting2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R_{{{\text{testing}}}}<^>{2}$$\end{document}, Radjusting2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R_{{{\text{adjusting}}}}<^>{2}$$\end{document}, and stability evaluations from 13 functional structures, with a second-order trigonometric nonlinear type model (SOTN) as the highest predictive performance. Stochastic optimization methods-including Modified Differential Evolution (MDE), Modified Nelder-Mead (MNM), Modified Simulated Annealing (MSA), and Modified Random Search (MRS)-were employed under three design scenarios to determine optimal wear parameters. The results revealed that epoxy composites containing 15 wt% NDFs exhibited the most substantial improvement, with a 95% reduction in specific wear rate (SWR) compared to neat epoxy and a 60% reduction relative to CDF-filled composites. The lowest optimized specific wear rate achieved was 1.086 x 10-5 mm3/N<middle dot>m. This work offers a comprehensive framework integrating material processing, statistical modeling, and stochastic optimization for the design of high-performance, wear-resistant epoxy composites.