Uçak Gövde ve Motor Bakımı - Makale Koleksiyonu

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https://hdl.handle.net/20.500.12695/313

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CFD study of jet fuel with ammonia - Hydrogen mixtures in a jet engine: Emissions and combustion characteristics analysis
(Elsevier, 2025) Alabaş, Hüsamettin Alperen
The growth of the aviation industry and the rapid increase in global transportation demand have further emphasized the importance of global efforts to reduce pollutant emissions. In this context, taking strategic and technological steps to lower greenhouse gas emissions in aviation has become inevitable to ensure environmental sustainability and effectively combat climate change. At the centre of these efforts lies the pursuit of environmentally friendly alternatives to hydrocarbon-based aviation fuels. In this study, the impacts of blending alternative fuels such as hydrogen and ammonia with kerosene in a GTM-120 mini gas turbine engine on flame temperature, CO, CO2, and NOX emissions were analysed. In the constant thermal power scenarios, the kerosene ratio was limited to a maximum of 50 %, while the ammonia-hydrogen mixture was applied in varying proportions ranging from 5 % to 45 %. CFD simulations conducted under non-premixed combustion conditions revealed that the introduction of hydrogen increases flame temperature and propagation speed. However, this also negatively affects combustion stability, and CO emissions could not be sufficiently reduced. In contrast, as the proportion of ammonia in the mixture increased, CO emissions decreased significantly, with average values dropping from 0.74 ppm to 0.0158 ppm. Ammonia, being an efficient hydrogen carrier, initially caused an increase in NOX emissions when combined with hydrogen due to the effect of the fuel NOX mechanism. At 50 % kerosene - %45 hydrogen - 5 % ammonia case, NOX emissions reached as high as 344.5 ppm. However, as the ammonia ratio in the fuel mixture increased, the flame temperature decreased, suppressing thermal NOX formation and reducing the average NOX emissions at the outlet to 14.26 ppm. Moreover the addition of ammonia reduced flame speed, which led to a significant decrease in incomplete combustion product CO emissions while increasing the amount of CO2 as a product of complete combustion. At the highest ammonia ratio, CO2 emissions reached up to 3.21 %. In conclusion, ammonia, which is low-cost and easy to store, when used together with hydrogen and kerosene in gas turbine engines, provides significant advantages with respect to emission control and combustion efficiency. This study presents a novel contribution to the literature by comprehensively evaluating the environmental performance and flame temperature of ammonia-hydrogen-kerosene ternary fuel blends under real engine conditions - an area that has mostly been addressed separately in previous studies. Thus, it offers valuable insight for the development of next-generation low-emission fuel strategies in gas turbine engine applications.
Convergence of iterative algorithm for G-nonexpansive mapping with digraph: application on G-variational inequality problem and signal recovery
(Taylor Francis, 2025) Yolaçan, Esra
The Halpern iteration method is among the most extensively studied approaches in the literature concerning the approximation of fixed points of G-nonexpansive mappings. In recent years, numerous extensions and modifications of this method have been proposed in various abstract settings. Among these, the formulation introduced by Tiammee et al., which adapts Halpern's iterative scheme to the context of Hilbert spaces endowed with a digraph structure, has garnered particular attention. This study investigates the convergence properties of G-nonexpansive mappings on a Hilbert space equipped with a digraph, thereby extending and enhancing the results previously obtained by Suzuki, Pang & Naraghirad and Tiammee et al. Moreover, a numerical example implemented in MATLAB R2016a is provided to illustrate and support the theoretical findings. Finally, by employing the concept of the G-variational inequality, as introduced by Kangtunyakarn in 2020, we illustrate the effectiveness of the proposed algorithm in the field of signal recovery, thereby highlighting its potential for real-world implementation.
Investigating The Modified UO-iteration process in Banach spaces by a digraph
(De Gruyter Brill, 2025) Yolaçan, Esra
Graph theory (GT) is a highly captivating area of study within applied mathematics. Over the last 50 years, the number of mathematicians contributing to research in this field has consistently risen. This surge in interest can largely be attributed to its vast potential for practical applications. It has found uses in various disciplines such as engineering, physical sciences, genetics, computer science, sociology, operations research and economics. Driven and encouraged by these points, we introduce and analyze the convergence theorems for the modified UO-iterative sequences applied to G-nonexpansive mapping in Banach spaces via a graph. In addition, the modified UO-iterative algorithm’s applications to image deblurring and signal enhancement are demonstrated.
A BRIEF STUDY CONCERNING RATIONAL TYPE CONTRACTION VIA A DIGRAPH AND DEFORMATION OF AN ELASTIC BEAM
(European Journal of Mathematics and Applications, 2024) Yolaçan, Esra
In this paper we firstly bring forward some findings for certain rational type expression in the sense of metric space with a digraph. Secondly, utilizing the proposed results, we assert a solution of elastic beam equations. Our results generalize the conclusions given by Banach, Kannan, Chatterjee, Fabiano so on.
On Prime Counting Functions Using Odd K-Almost Primes
(2024) Yolaçan, Esra
This work takes an interesting diversion, revealing the extraordinary capacity to determine the precise number of primes in a space tripled over another. Exploring the domain of K-almost prime numbers, this paper provides a clear explanation of the complex idea. In addition to outlining the conditions under which odd K-almost prime numbers must exist, it presents a novel method for figuring out how often odd numbers are as 2-almost prime, 3-almost prime, 4-almost prime, and so on, up to a specified limit n. The work goes one step further and offers useful advice on how to use these approaches to precisely calculate the prime counting function, ?(n). Essentially, it offers a comprehensive exploration of the mathematical fabric, where primes reveal their mysteries in both large and small spaces.
SOME RESULTS ON G?CONTRACTION WITH PROPERTY (M)
(Uzbek Mathematical Journal, 2023) Yolaçan, Esra
Based on the results of Berinde and P ?acurar, we present the notion of GC? modified Reich contractions with property (M) in Banach spaces (curtly BS) including a graph. Our outcomes enlarge varied comparable consequences in the existing litterateur.
An Analysis of Dalaman International Airport's (LTBS) Noise Prediction Model and Assessment of its Noise Impact
(Emeral Publishing, 2023) Kafalı, Haşim; Güçlü, İbrahim
Purpose: In this context, this study aims to obtain information about the noise levels emitted to the environment by modeling the noise map of Dalaman Airport and correlating these noise values according to the END (Environmental Noise Directive) and WHO (World Health Organization) limits. Methodology: Dalaman Airport AIP (Aeronautical Information Publication) and 2022 flight data from the airport were analyzed. The noise levels exposed to schools and health institutions were determined using the Cnossos-Eu calculation method. Findings: Maximum noise levels were obtained as Lden 92.29 dB(A), Lday 85.24 dB(A), Levening 89.00 dB(A), and Lnight 85.23 dB(A) according to the noise indicators. Limit values recommended by END and WHO according to noise indicator types and measurement results were correlated and evaluated. Originality: In the noise modeling of Dalaman Airport, there has previously been no evaluation of the noise limits recommended according to END or WHO in the literature.
A Study on (?,?) Weakly Contractive Mapping via (F,h) Upper Class
(Journal of the Institute of Science and Technology, 2023) Yolaçan, Esra
Branciari reorganized the notion of metric to attain a novel distance function by replacing the triangular inequality with the quadrilateral inequality. The reorganized metric function was said rectangular metric in some resources, or general metric in some others. Ansari introduced a more general function so-called upper class. Inspired and motivated by this facts, we give an extansion of weakly contractive mapping via upper class type II in the setting of Branciari metric space. An application is given here to prove new fixed point results for graphic weakly contractive mappings in Branciari metric space endowed with a graph. Moreover, we derive an example in support of our main results.
Convergence of a Four-Step Iteration Process for G-nonexpansive Mappings in Banach Spaces with a Digraph
(Fundamentals of Contemporary Mathematical Sciences, 2023) Yolaçan, Esra
This review reckons with iterative scheme of Thianwan to approximate a common fixed point for four G-nonexpansive mappings (tersely G-nm). We verify several convergence results for in this way mappings in Banach space by dint of a digraph.
ITERATION SCHEME FOR APPROXIMATING FIXED POINTS OF G-NONEXPANSIVE MAPS ON BANACH SPACES VIA A DIGRAPH
(Kütahya Dumlupınar Üniversitesi, 2023) Yolaçan, Esra
In this writing, an influential modified multistep iterative process for finding a common fixed point of G-nonexpansive maps is presented. Some convergence theorems are constructed by Property P for the recommended schema on Banach spaces by which digraph. Two numerical examples are given to illustrate the convergence behavior and the validity of the process. The achieved conclusions enlarge, generalise and complement some well-known fixed point results from the literature.
A short note on Hardy-Rogers contractive conditions
(The Aligarh Bulletin of Mathematics, 2022) Yolaçan, Esra
In this writing, we give some theorem in metric space under cyclic coupled Hardy-Rogers contractive conditions. Also, we offer a different perspective on this condition in metric space involving a graph.
The preparation of chitosan membrane improved with nanoparticles based on unsaturated fatty acid for using in cancer-related infections
(SAGE, 2020) Kızıloğlu, Abdullah; Kılıçay, Ebru; Karahaliloğlu, Zeynep; Hazer, Baki; Denkbaş, Baki Emir
This study includes the design of a chitosan membrane decorated with unsaturated fatty acid–based carrier system for cancer treatment and antibacterial application. For this, polystyrene-graft-polyoleic acid-graft-polyethylene glycol was prepared by free radical polymerization and characterized. Nanoparticles and caffeic acid–loaded nanoparticles were prepared by solvent evaporation technique and optimized. The short-term stability of nanoparticles was investigated at 4°C. Drug encapsulation and loading efficiency were evaluated. The chitosan membrane and caffeic acid–loaded nanoparticles embedded into chitosan membrane were fabricated. The caffeic acid loaded nanoparticles embedded into chitosan membrane showed controlled release. The mechanical properties of all samples were investigated. The caffeic acid–loaded nanoparticles embedded into chitosan membranes indicated excellent antibacterial properties against the Escherichia coli and Staphylococcus aureus. The anticancer activity of all the samples was evaluated against SaOS-2 human primary osteogenic sarcoma and MC3T3-E1 pre-osteoblast cell lines by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay, the flow cytometry and double staining methods. As a result, the designed carrier system showed great potential to cancer-associated infections treatment in bone cancer cases.
Electrospinning of Fatty Acid-Based and Metal Incorporated Polymers for the Fabrication of Eco-Friendly Fibers
(Wiley, 2022) Erdem, Çağlar; Işık, Tuğba; Horzum, Nesrin; Hazer, Baki; Demir, Mustafa M.
Accumulation of plastic wastes occupies large space in gyres of the oceans called the 7th continent. This high-level concentration of toxic plastic wastes causes harmful consequences for marine life, therefore petroleum-originated plastics must be replaced (or at least partially) with natural resources. The environmental trends in material preparation promote the utilization of greener methods and materials when the limited primary sources are considered. Starting from the fatty acid macroperoxide initiators, synthesis of bio-based polymers using less commercial chemicals and stepwise green synthesis schemes could be possible in the near future. In this research, autoxidized vegetable oil initiators (castor, limonene, and soybean oil) containing metal nanoparticles (silver, platinum, and gold) are employed for free radical polymerization of vinyl monomers. The metal loaded and vegetable oil-based polymers are processed by electrospinning and end up with the successful fabrication of continuous fibers. Ag-loaded ricinoleic acid based polymers show notable antibacterial activity against Escherichia coli. This approach offers a remarkable minimization of the initiator consumption in the synthesis of such synthetic macromolecules as well as nanoparticle containing polymer composites while still maintaining the ease of processing. Transforming the obtained graft copolymers to electrospun nanofibers facilitates the use as support materials for antibacterial surfaces.
One-Pot Preparation of Electroactive Shape Memory Polyurethane/Carbon Black Blend
(Springer, 2021) Uranbey, Leyla; Unal, Halil Ibrahim; Çaliş, Gökçe; Gümüş, Ömer Yunus; Katmer, Şükran; Karataş, Çetin
Shape memory polymers are the materials that can recover their original shape after a large deformation when exposed to an external stimulus such as electric field, pH, temperature, light, magnetism or humidity. With these properties, it is possible to use them in many areas in the industry. In this study, a shape-memory polymer compound was developed which is capable of changing its shape when subjected to an external voltage. Electroactive shape memory polymer compound was prepared by mixing commercially available and economically viable thermoplastic shape memory polyurethane (SMPU) with carbon black (CB), which has low cost and high electrical conductivity, by adding at various proportions. Conductivity, structural, morphological, homogeneity, thermal, rheological and shape memory characterizations of the SMPU/CB blend were carried out by four-probe measurements, ATR-FTIR spectroscopy, x-ray diffraction analysis, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analyses, melt flow index (MFI), and a thermal camera imaging methods, respectively. The effects of CB loading ratios on these characteristics of SMPU/CB blends were investigated. It was concluded that SMPU/20CB blend can be used as a commercial material having shape memory characteristics.
Şekil hafızalı poliüretanın enjeksiyonla kalıplanmasında parça kalitesi
(2021) Katmer, Şükran; Karataş, Çetin
Akıllı malzemenin bir türü olan şekil hafızalı polimerler (ŞHP) son yıllarda endüstriyel uygulamalarda yaygınlaşmaktadır. Şekil hafızalı polimerlerin bir türü olan termoplastik şekil hafızalı poliüretan (ŞHPU) kolay kalıplanabilme ve tekrar kullanılabilme özellikleri ile ilgi çekmektedir. Mevcut termoplastiklerde olduğu gibi ŞHPU’dan üretilen parçaların da kalıcı şekillerinin verilmesinde enjeksiyon kalıplamanın yaygın kullanılması beklenmektedir. Bu çalışmada, enjeksiyon kalıplamayla kalıcı şekilleri verilmiş ŞHPU numunelerde parça kalitesi; eksik baskı, hava sıkışması ve parça ağırlığı üzerinden araştırılmıştır. Enjeksiyon basıncı, enjeksiyon sıcaklığı, kalıp sıcaklığı, ütüleme basıncı ve süresi, soğutma süresi parametreleri ile kalıpta eksik baskı, hava sıkışması ve numune ağırlığı arasındaki ilişkiler deneysel olarak incelenmiştir. Deney tasarımı, Taguchi L27 ortogonal dizilim ile hazırlanmış, deneysel veriler varyans analiziyle değerlendirilmiştir. Eksik baskı oluşumuna enjeksiyon sıcaklığı ve basıncının etkileri istatistiksel yönden anlamlı bulunurken, hava sıkışması ise enjeksiyon basıncı ve kalıp sıcaklığından etkilenmiştir. Numune ağırlığı üzerinde en etkili parametrelerin ise sırasıyla enjeksiyon basıncı ve sıcaklığı, kalıp sıcaklığı ve ütüleme basıncı olduğu bulunmuştur.
Synthesisof Biobased Block Copolymers Using A Novel Methacrylated Methyl Salicylate and Poly (3-Hydroxybutyrate)
(Chemistry Europe, 2022) Hazer, Baki; Subramaniyan, Sathiyaraj; Zhang, Baozhong
A novel biobased vinyl monomer was synthesized by the reaction of methyl salicylate with methacrylic anhydride. The resulting salicylate based monomer was polymerized by reversible addition fragmentation transfer(RAFT) polymerizations using two or three trithiocarbonate functionalizedpoly(3-hydroxybutyrate) macroagents. The molecular structures of the obtained polymers were confirmed by NMR spectroscopyand GPC analysis.The resulting block copolymers showed glass transition temperature (Tg) at 5°C and melting temperature (Tm) at 160°C according to DSCresults .Compared to PHB, the obtained block copolymers displayed enhanced thermal stabil-ity according to TGA results.
Beech (Fagus orientalis) wood modification through the incorporation of polystyrene-ricinoleic acid copolymer with Ag nanoparticles
(Springer, 2022) Can, Ahmet; Sivrikaya, Hüseyin; Hazer, Baki; Palanti, Sabrina
Cellulose is an international journal devoted to the dissemination of research and scientific and technological progress in the field of cellulose and related naturally occurring polymers. The journal is concerned with the pure and applied science of cellulose and related materials, and also with the development of relevant new technologies. This includes the chemistry, biochemistry, physics and materials science of cellulose and its sources, including wood and other biomass resources, and their derivatives. Coverage extends to the conversion of these polymers and resources into manufactured goods, such as pulp, paper, textiles, and manufactured as well natural fibers, and to the chemistry of materials used in their processing. Cellulose publishes review articles, research papers, and technical notes.
Herceptin-conjugated magnetic polystyrene-Agsbox nanoparticles as a theranostic agent for breast cancer
(SAGE, 2022) Karahaliloğlu, Zeynep; Kılıçay, Ebru; Hazer, Baki
Breast cancer is a malignant tumor, which has derived from cells of the breast. Further, a relatively rapid metastasis, and resistance development against all the conventional drug combinations are major clinical issues in breast cancer patients as well as limitations like toxicity, genetic mutation, and metastasis make difficult the use of conventional therapy methods such as chemotherapy, radiotherapy, and local surgery. Therefore, considering the urgent needs, and high death rate in breast cancer cases, the development of new diagnosis and treatment regimens which diagnosed at the early stage and protected normal tissues required for clinical applications. Recently, the combination of tumor diagnosis and treatment within a single platform is a novel perspective, and magnetic nanoparticles are potential candidate owing to their low toxic effect, biocompatibility, biological degradability, superior magnetic properties, and targeting ability to overcome the problems of conventional diagnosis and therapy techniques. Considering these restrictions and requirements, the goal of this research was to investigate the potential of an innovative theranostic agent, which is soybean oil-based polystyrene (PS)-g-soybean oil graft copolymer containing AgNPs (PS-Agsbox) for treatment and MRI-based diagnosis of cancer. Herein, we designed targeted magnetic PS-Agsbox nanoparticles carrying thymoquinone (TQ) that is known for its anticancer potential against breast cancer, and herceptin (HER), which is to bind to the HER2 receptor protein on the surface of HER2-positive tumor cells, and acts by blocking the effects of it. We have successfully demonstrated selective binding, effective uptake of HER-conjugated magnetic PS-Agsbox nanoparticles into MDA-MB-231 (human breast carcinoma cells, a HER2-underexpressing cell line) and SKBR-3 (human breast cancer cells, a HER2-overexpressing breast cancer cell line) cell lines while no effect against L929 (mouse fibroblast cell line). Moreover, the magnetic resonance (MRI) properties of HER-conjugated magnetic PS-Agsbox nanoparticles were also confirmed.
Synthesis of polystyrene-polyricinoleic acid copolymer containing silver nano particles for dispersive solid phase microextraction of molybdenum in water and food samples
(Elseiver, 2022) Tüzen, Mustafa; Altunay, Nail; Hazer, Baki; Afshar Mogaddam, Mohammad Reza
Polystyrene-polyricinoleic acid copolymer containing silver nano particles (AgPSrici) was synthesized and used in separation of molybdenum from different aqueous and foodstuff samples during a dispersive-µ-solid phase extraction approach. The synthesized nano particles were verified using Fourier transform infrared spectroscopy. An electrothermal atomic absorption spectrometry has been used for measurement of the studied ions. AgPSrici amount pH, sample volume, elution solvent kind, and the time of extraction were the effective parameters that were optimized by one-variable-at-one-time method. Analytical data of the method was calculated and limit of detection, relative standard deviation, limit of quantification were 0.022 µg L? 1 , 2.9%, 150, and 0.066 µg L? 1 , respectively. The synthesized adsorption capacity was obtained 170 mg g? 1 . Accuracy of the method was studied by performing the method on certified reference materials and the presence of different interfering ions was studied. Molybdenum content of different water and foodstuffs was determined by the introduced method.
Prevention of urinary infection through the incorporation of silver– ricinoleic acid–polystyrene nanoparticles on the catheter surface
(SAGE, 2021) Koç, Hazal; Kılıçay, Ebru; Karahaliloğlu, Zeynep; Hazer, Baki; Denkbaş, Baki Emir
Nosocominal infections associated with biofilm formation on urinary catheters cause serious complications. The aim of this study was to investigate the feasibility of the polyurethane (PU) catheter modified with tetracycline hydrochloride (TCH) attached Ag nanoparticles embedded PolyRicinoleic acid-Polystyrene Nanoparticles (PU-TCH-AgNPs-PRici-PS NPs) and the influence on antimicrobial and antibiofilm activity of urinary catheters infected by Escherichia coli and Staphylococcus aureus. For this purpose, AgNPs embedded PRici graft PS graft copolymers (AgNPs-PRici-g-PS) were synthesized via free radical polymerization and characterized by FTIR, HNMR and DSC. AgNPs-PRici-PS NPs were prepared and optimized by the different parameters and the optimized size of nanoparticle was found as about 150?±?1?nm. The characterization of the nanoparticles and the morphological evaluation were carried out by FTIR and SEM. Short term stability of nanoparticles was realised at 4°C for 30?days. In vitro release profiles of TCH and Ag NPs were also investigated. The formation of biofilm on PU modified TCH-Ag NPs-PRici-PS NPs, was evaluated and the biocompatibility test of the nanoparticles was realized via the mouse fibroblast (L929) and mouse urinary bladder cells (G/G An1). This is the first time that TCH-AgNPs-PRici-PS NPs used in the modification of PU catheter demonstrated high antimicrobial and antibiofilm activities against the urinary tract infection.

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