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Öğe Coupled cylindrical quantum well wires in broken symmetry: effects of intense laser field on the harmonic generations(Springer Nature, 21.10.2024) Alaydin Behçet Özgür; Ozan Öztürk; Didem Altun; Emine ÖztürkThis study explores the high harmonic generations in GaAs/AlxGa1-xAs asymmetric coupled cylindrical quantum well wires (CCQWWs) under varying intense laser fields (ILFs). The structural parameters and theoretical framework are detailed, including the Schrödinger equation for the CCQWW heterojunction and the Floquet method to model ILF effects. Numerical simulations reveal alterations in the confinement potential and energy states of CCQWWs with increasing ILF intensity. Notably, significant changes occur in the potential well shape, influencing the localization of energy states. Transition energies and dipole moment matrix elements are analyzed, highlighting shifts in resonance peaks and their intensities. The study identifies blue-shift points at α0 (ILF parameter) values of 4.4 nm, 4.7 nm, and 3.7 nm for transition energies E21, E31/2, and E41/3, respectively, followed by red-shift trends as α0 increases further. Maximum enhancements are observed in the second harmonic generation coefficient at ILF α0 = 6 nm and the third harmonic generation coefficient at α0 = 8 nm, which is 1000 times higher than at α0 = 0 nm. These findings underscore the potential for enhancing semiconductor device production through optimized ILF induced high harmonic generation.Öğe CH4 production potential of autotrophic nitrification bacteriaproduced in the submerged nitrification bioreactor in thelaboratory and kinetic analysis(07.07.2024) Alhraishawi, AliIn this study, CH4 production capacity of nitrification bacteria (NB) obtainedfrom the submerged biofilter in the laboratory was investigated. Biochemicalmethane potential (BMP) test was carried out with the NB amount of zero(control, CR), 5% (R1), 10% (R2), and 15% (R3) at a temperature of about 37 ±0.5°C. Compared to the CR, significantly higher cumulative CH4 volume ofabout 290, 490, and 715 mL were determined in the R1, R2, and R3, respec-tively. All the applied kinetic models gave good results (R2 ≥0.97), while theTransference Function and First-order models provided the better R2 values.The delay phase (λ) was not observed in the AD process, and CH4 productionstarted immediately on the first day of operation. The predicted k value of0.133 day−1 was high in CR, while it was approximately between 0.078 and0.112 day−1 for the higher amount of NB containing BMP units, which indi-cated that the AD required long reaction time.Öğe Effects of microwave irradiation at various temperatures onbiosludge disintegration(18/06/2024) Alhraishawi, AliThe waste biological sludge disintegration by using microwave irradiationwas investigated at a ramping rate of 2°C/min and 5 min holding time atvarious target temperatures. Significant disintegration of biosludge wasobserved and the highest disintegration degree was determined about82% at the temperature of 110°C. Increase of target temperature elevatedthe energy needs to 98, 123 and 148 kWh/kg TS at the temperatures of75°C, 90°C and 110°C, respectively. The gradual increase of sugar andprotein in the sludge slurry with increasing temperatures indicates suc-cessful degradation. The microwave pretreatment increased the specificsurface area of the sludge by particle size reduction. The specific surfacearea of raw sludge was 70 m2/kg and rose to approximately 253.7 m2/kg at110°C with an increment ratio of 260%. Although a significant NH4–Nrelease was not observed, PO4–P concentrations increased from 11.0 mg/Lto 16.3, 20.7 and 29.2 mg/L at the temperatures of 75°C, 90°C, 110°C,respectively. While the specific filter resistance of waste biological sludgewas about 1.0 × 1013, increasing the microwave target temperature, theability of dewatering decreased and the highest SFR value of 5.1 × 1014was observed at the temperature of 110°C.Öğe Imidazole-Derived Alkyl and Aryl Ethers: Synthesis, Characterization, In Vitro Anticancer and Antioxidant Activities, Carbonic Anhydrase I–II Inhibition Properties, and In Silico Studies(03/05/2024) Faris, Mays; Özcan, İbrahim; Erdoğan, Taner; Tahtacı, HakanImidazole derivatives display extensive applicationsin pharmaceutical chemistry and have been investigated asbioactive compounds for medicinal chemistry. In this study,besides the starting materials (3a−c and 4a−c), synthesis,characterization, and biological activity studies were conductedon a total of 18 compounds, nine of which are known and the othernine are original. The compounds investigated in the study are aseries of alkyl (7−15) and aryl (16−24) ether derivatives bearingsubstituted phenyl and imidazole rings, which were characterizedusing various methods including 1H NMR, 13C NMR, FT-IRanalysis, elemental analysis, and mass spectroscopy. Computer-aided drug design studies have been carried out to predict the biological activities of compounds. Besides DFT calculations, thebinding affinities of the compounds to EGFR, VEGFR2, FGFR1, HSP90, hCA I, and hCA II were investigated. Additionally, drug-likeness and ADME analyses were performed on the compounds. Anticancer, antioxidant, and enzyme inhibition activity tests wereperformed in biological activity studies on the synthesized compounds. Among the synthesized compounds, compounds 17 and 19−24 generally exhibited inhibition profiles against the widespread cytosolic hCA I isozyme with IC50 values ranging from 4.13 to 15.67nM and cytosolic hCA II isozyme with IC50 values ranging from 5.65 to 14.84 nM. L929 (mouse fibroblast cell line) was used as thecontrol healthy cell line, and MCF7 (breast cancer), C6 (rat glioblastoma), and HT-29 (colon cancer) cells were used in cell culturestudies as cancer cell lines. Before the study on cancer cells, all compounds were examined on healthy cells, and their cytotoxicity wasdetermined. As a result of these data, studies continued with six compounds determined to be nontoxic. On cancerous cells, it wasdetermined that compounds 3a, 3b, 4a, 4b, 4c, and 7 had cytotoxic effects on both colon cancer and brain tumors. It was found thatcompound 3b had a more toxic effect than cisplatin on the glioma cell line with an IC50 value of 10.721 ± 0.38 μM, and compound3a had a more toxic effect on the colon cancer cell line with an IC50 value of 20.88 ± 1.02 μM. However, it was determined that thesame compounds did not have a statistically significant effect on breast cancer. Flow cytometry studies also showed that when theIC50 dose of compound 3b was applied to the C6 cell line, the cells tended to early and late apoptosis. Additionally, it has beenshown by flow cytometry that the cell cycle stops in the G0/G1 phase. A similar effect was observed in the colon cancer cell line withcompound 3a. Compound 3b caused early and late apoptosis of the colon cancer cell line with the applied IC50 dose and stopped thecell cycle in the G0/G1 phase. Finally, the FRAP method studied all synthesized compounds’ antioxidant effects. According to themeasured antioxidant power results, it was determined that no compound had a more effective reducing power than vitamin E.Öğe Methane Production and Nutrient Recovery After Applying Microwave Technology in Sewage Sludge Pretreatment(24/03/2024) Alhraishawi, AliThis study investigates the effect of microwave treatment on the disintegration of municipal activated sludge. Sludge samples underwent heating at a targeted temperature of 90 °C for 35 min, with a 5-min retention time. Soluble chemical oxygen demand, sugars, proteins, nitrogen, and phosphorus exhibited notable increases compared to untreated samples. Results indicate a substantial (42–45%) rise in CH4 production during the anaerobic digestion process of the disintegrated sludge compared to the untreated counterpart CH4 production was estimated using a transference model, which showed the best fit compared to other models. Further experimentation involved testing digested sludge with excess soluble NH4–N and PO4–P for the recovery of struvite at a 1.50/1/1 (Mg/N/P) ratio. The findings reveal that up to 90.1% and 90.4% of PO4–P and NH4–N, respectively, can be efficiently removed from the solution. Despite the increased CH4 output, the energy recovered was insufficient to offset the electrical energy used by the microwave. There was a significant deterioration in sludge filter resistance due to the increase in fine particles and bound water after anaerobic digestion of the pretreated sludge.Öğe Coupled cylindrical quantum well wires in broken symmetry: effects of intense laser field on the harmonic generations(21.10.2024)This study explores the high harmonic generations in GaAs/AlxGa1-xAs asymmetric coupled cylindrical quantum well wires (CCQWWs) under varying intense laser fields (ILFs). The structural parameters and theoretical framework are detailed, including the Schrödinger equation for the CCQWW heterojunction and the Floquet method to model ILF effects. Numerical simulations reveal alterations in the confinement potential and energy states of CCQWWs with increasing ILF intensity. Notably, significant changes occur in the potential well shape, influencing the localization of energy states. Transition energies and dipole moment matrix elements are analyzed, highlighting shifts in resonance peaks and their intensities. The study identifies blue-shift points at α0 (ILF parameter) values of 4.4 nm, 4.7 nm, and 3.7 nmfor transition energies E21, E31/2, and E41/3, respectively, followed by red-shift trends as α0 increases further. Maximum enhancements are observed in the second harmonic generation coefficient at ILF α0 6 nm and the third harmonic generation coefficient at α0 8 nm, which is 1000 times higher than at α0 0 nm. These findings underscore the potential for enhancing semiconductor device production through optimized ILF induced high harmonic generation.Öğe Zaman Gecikmeli Kesir Dereceli Kaotik Sistemlerin Senkronizasyonu ve FPGA Uygulaması(Black Sea Journal of Engineering and Science, 15.07.2024) Değirmen, Semih CanElektronik tabanlı sistemlerin kontrolü, geliştirilmesi ve birçok işletme hatasının tespiti için matematiksel olarak ifade edilebilmesi oldukça önemlidir. Matematiksel olarak ifade edilebilen sistemlerde, geliştirilebilmesinin yanında birçok problemin tespit edilmesini de kolaylaştırır. Özellikle haberleşme sistemleri ve bu sistemlerdeki taşıyıcı sinyallerin, haberleşme protokollerinin matematiksel modellenmeleri ve geliştirilmesi ile ilgili çalışmalar son dönemde artmaktadır. Özellikle karmaşık yapısı ile dikkat çeken kaotik tabanlı sistemlerin haberleşme sistemlerinde kullanılmasıyla bilgi sinyallerinin güvenilirliği artırılmıştır. Ancak kaotik sistemlerin tam dereceli olarak modellenmesi, özellikle kullanıldığı haberleşme sistemlerindeki hatalı bit sayılarını artırmakta ve zaman gecikmelerinden kaynaklı uzun senkronizasyon sürelerine neden olmaktadır. Bu nedenle kaotik sistemlerin kesir dereceli olarak modellenmesinin yanında verici-alıcı sitemlerin mümkün olan en kısa sürelerde senkronize olmaları için sistemler arasındaki zaman gecikmelerinin de dikkate alınması gereklidir. Bu çalışmada haberleşme sistemlerinde kullanılan kaotik bir sistemin kesir dereceli olarak elde edilmesi, daha sonra ise bir kontrolör ile zaman gecikmelerinden kaynaklı senkronizasyon gecikmelerinin azaltılması amaçlanmıştır. Yapılan çalışmada Charef yaklaşım metodu kullanılarak kesir dereceli kaotik sistem tasarımı yapılmış ve bulanık mantık tabanlı bir kontrolör ile zaman gecikme sürelerinden kaynaklı senkronizasyon süresi azaltılmıştır. Neticede, kesir dereceli olarak gerçek sistem davranışı elde edilen bir kaotik sitemin bir kontrolör ile senkronizasyon sürelerinin azaltılabildiği gösterilmektedir. Yapılan çalışma önce bilgisayar benzetimi ile daha sonra ise FPGA kullanılarak deneysel uygulaması gerçekleştirilmiş ve doğrulanmıştır.Öğe LSTM Deep Learning Techniques for Wind Power Generation Forecasting(Journal of Soft Computing and Artificial Intelligence, 15.06.2024) Ahmed Babiker Abdalla, IbrahimWind power generation forecasting is crucial for the optimal integration of renewable energy sources into power systems. Traditional forecasting methods often struggle to accurately predict wind energy production due to the complex and nonlinear relationships between wind speed, weather parameters, and power output. In recent years, deep learning techniques have emerged as promising alternatives for wind power forecasting. This conference paper provides a comprehensive review of deep learning techniques, with a specific focus on Long Short-Term Memory (LSTM) networks, for short-term wind power generation forecasting. Leveraging insights from recent research and empirical evaluations, this paper explores the effectiveness of LSTM networks in capturing temporal dependencies in wind data and improving prediction accuracy. The review highlights the potential of LSTM-based models to enhance the integration of wind energy into power systems and provides guidance for future research in this area.Öğe A beetroot-based beverage produced by adding Lacticaseibacillus paracasei: an optimization study(2024) Durukan Gamze; Sari FerdaThe present study aimed to optimize the production conditions of a beetroot-based beverage using Lacticaseibacillus paracasei. The experiment was meticulously planned and executed using the Box–Behnken design in Response Surface Methodology (RSM), which provided 17 different combinations. The independent variables in this study included the heat treatment temperature (60–80℃, the heat treatment time (10–30 s), and the incubation temperature (24–36℃). The variables evaluated in this study included pH, total acidity (TA), total phenolic content (TPC), total betalain content (TBC), yellow color (OD420), general acceptance (GA), and total count of lactic acid bacteria (LAB). The samples were determined to have TPC ranging from 67.90 to 437.15 mg GA/L and TBC ranging from 147.52 to 747.21 mg/L. The samples subjected to incubation temperatures of 30℃ and 36℃ were typically favored by the panelists and exhibited better results in terms of chemical analysis compared to the samples incubated at 24℃. According to RSM, heat treatment at 60°C for 22 min and an incubation temperature of 31°C were the optimum production conditions. Under these optimal conditions, RBJ has maximum TBC, total LAB, and GA scores, indicating nutrient-dense and appealing to consumers.Öğe Production of red beetroot juice by different methods: Kinetics of microbial growth, sugar consumption, and acid production(2024) Duyar Sura Melisa; Sari Ferda; Karaoglan Hatice Aybükemanufacturing, although spontaneous methods have been employed since ancient times. The objective of this study was to investigate the effect of different production methods on red beetroot juice (RBJ). For this purpose, as a starter culture, the probiotic Lactibasillus paracasei (Lc. paracasei) was inoculated into the RBJ samples after pasteurization. Also, the growth of cells, acid production, and substrate utilisation were monitored throughout the fermentation process of RBJ under two different methods of fermentation. The samples produced by the addition of Lc. paracasei demonstrated a slightly lower decrease in pH values in comparison to the samples obtained by the spontaneous method. The concentration of lactic acid (LA) and acetic acid (AA) at the end of fermentation reveals that Lc. paracasei exhibits a greater capacity for both LA and AA generation compared to the spontaneous method. The ratios of LA and AA molar concentrations of RBJ were determined to be 1.7 and 3.6 for the samples produced by adding Lc. paracasei and the spontaneous method, respectively. The samples produced by adding Lc. paracasei exhibited a greater consumption of sucrose. Both fermentation methods provide LAB counts exceeding 8 log CFU/mL at the end of fermentation. Time demonstrated a significant correlation with LA and AA in the method by adding Lc. paracasei (r = 0.942 and 0.745), respectively (p < 0.01). In both methods, it was demonstrated that while sucrose content decreased during the fermentation period, fructose and glucose content remained constant (p < 0.05).Öğe Linear and nonlinear optical properties of a superlattice with periodically increased well width under electric and magnetic fields(Micro and Nanostructures, Nisan 2022) Altun, Didem; Öztürk, Ozan; Alaydin, Behçet Özgür; Öztürk, EmineIn this paper, we have studied the electronic and optical properties of GaAs/AlxGa1-xAs superlattice with periodically increased well width. Under effective mass approximation, the finite element method is used to obtain wavefunctions and corresponding energy eigenvalues for several electric field (F) and magnetic field (B) values. We have shown that the increasing well width has a major effect on the localization of the first two energy states. The direction of the applied electric field shifts the localization position of the probability density of electrons to the left and right. For B = 0 (according to the parameters used), F = 5 kV/cm (especially for the difference between the first two energy levels (E12)) is a critical value. While the E12 value decreases in the range from 30 kV/cm to 5 kV/cm, it increases for the 5 < F < 30 kV/cm range. This behavior causes a red or blue shift in the optical spectrum. Also, F = 30 kV/cm causes more change in the structure than F = 30 kV/cm. In addition, the localization of the electrons is observed in the center of the superlattice under applied magnetic fields. The optical absorption coefficients and the refractive index changes are affected by applied F and B intensities. We can say that the electro-optical features of the superlattice have changed significantly with the combined effect of F and B values. This is desired for semiconductor optical device applications to have stable performances.Öğe Linear and nonlinear optical properties of a superlattice with periodically increased well width under electric and magnetic fields(Micro and Nanostructures, Nisan 2022) Altun, Didem; Öztürk, Ozan; Alaydin, Behçet Özgür; Öztürk, EmineIn this paper, we have studied the electronic and optical properties of GaAs/AlxGa1-xAs superlattice with periodically increased well width. Under effective mass approximation, the finite element method is used to obtain wavefunctions and corresponding energy eigenvalues for several electric field (F) and magnetic field (B) values. We have shown that the increasing well width has a major effect on the localization of the first two energy states. The direction of the applied electric field shifts the localization position of the probability density of electrons to the left and right. For B = 0 (according to the parameters used), F = 5 kV/cm (especially for the difference between the first two energy levels (E12)) is a critical value. While the E12 value decreases in the range from 30 kV/cm to 5 kV/cm, it increases for the 5 < F < 30 kV/cm range. This behavior causes a red or blue shift in the optical spectrum. Also, F = 30 kV/cm causes more change in the structure than F = 30 kV/cm. In addition, the localization of the electrons is observed in the center of the superlattice under applied magnetic fields. The optical absorption coefficients and the refractive index changes are affected by applied F and B intensities. We can say that the electro-optical features of the superlattice have changed significantly with the combined effect of F and B values. This is desired for semiconductor optical device applications to have stable performances.Öğe Dikey Bir Kanalda Bulunan Farklı Şekilli Elektronik Eleman Çiftinden Olan Taşınım Isı Transferinin Değerlendirilmesi(TMMO, Eylül-Ekim 2024.)Bu çalışmada, birbirine paralel dikey levhaların sol yüzeyi üzerinde iki adet yamuk geometrili sabit ısı akılı elektronik engel bileşenlerinin bulunduğu bir kanalda karışık taşınımla ısı transferi ve engeller etrafındaki akışkan hareketi sayısal olarak incelenmiştir. Sayısal araştırma, zamandan bağımsız, laminer ve iki boyutlu olarak süreklilik, momentum ve enerji denklemlerinin Ansys-Fluent bilgisayar programıyla çözülmesiyle gerçekleştirilmiştir. Akışın kanal içerisindeki ısınmış engel elemanlarına yönlendirilmesi amacıyla kanalın sağ üst yüzeyiyle 30o ve 45o açı yapan akış yönlendirici kanatçıklar yerleştirilmiştir. Kanalın engel elemanları harici diğer yüzeyleri ve akış yönlendiriciler adyabatiktir. Kanalda kullanılan su akışkanı sıkıştırılamaz olup, kanala giriş sıcaklığı 293 K’ dir. Çalışmada kullanılan Reynolds sayısı (Re) değeri 1000 iken; değiştirilmiş Richardson sayısı (Ri*) aralığı 50-150 ve Akış Geçiş Mesafesi (AGM) oranları 3.33 ve 4 olarak alınmıştır. Çalışmanın sonuçları, literatürdeki deneysel ve sayısal sonuçlarla kıyaslanmış ve oldukça uyumlu oldukları görülmüştür. Sonuçlar, Ri* sayısına göre farklı AGM ve kanatçık açılarında engellerin toplam ortalama Nu sayıları (Num), yüzey sıcaklıkları (Ts) ve akışkanın basınç düşüşünün (∆p) değişimleri olarak incelenmiştir. Ayrıca, değişik AGM oranları ve Ri* değerlerinde karışık taşınımın hız ve sıcaklık konturu dağılımları değerlendirilmiştir. AGM’nin 4 ve Ri*=150 olduğu değerler için Num sayısının 45o açılı kanatçıklı durumda kanatçıksız duruma göre %1.54 daha fazla olduğu belirlenmiştir.Öğe Investigation of forced convection heat and moisture transfer for semi-circular moist objects by using an impinging hot air jet flow(Elsevier, OCTOBER 2024)Drying is used as a preservation method for berries and greenstuffs. Thanks to the drying process, most of the water in the food is removed, creating an unsuitable environment for the activities of microorganisms. In this study, the heat and mass transfer characteristics of semi-circular moist objects placed at different angles (B) of 0 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees, and at different distances (H/D) of 5, 4, and 3.33 parallel to the impinging hot air jet flow were numerically investigated. Numerical calculations were carried out by solving the forced convection heat and mass transfer equations for two-dimensional, steady, laminar, and incompressible flow using the AnsysFluent program. For drying, moisture transfer equations were also resolved by typing a User-Defined Function (UDF) code in Ansys-Fluent. While the temperature of the jet flow (Tjet) is 323 K, the moist object surface temperature (Ts) is 298 K. Calculations were conducted for different values of Re numbers: 300, 400, and 500. The effects of the placement angles and positions of the moist object on the average Nu number (Nua) were examined for different Re numbers. Additionally, temperature and moisture variations at the midpoint length of the object along the x-axis-(X) were evaluated in detail. However, streamline distributions around moist objects, and temperature and moisture isotherms inside the moist objects were visualized at distinct H/D distances and Re numbers for B = 0 degrees, 45 degrees, and 90 degrees. Velocity and temperature contour distributions were displayed for all B angles and H/D distances for the Re number of 500. The consequences of this work were matched with the computational and empirical consequences of the studies conducted in the literature, and it was noticed that the outcomes were in good agreement with each other. For Re = 500 and H/D = 3.33, an increase in the B from 0 degrees to 30 degrees resulted in a 17.98 % increase in the Nua. Furthermore, the lowest moisture rates were reached at B = 45 degrees - H/D = 3.33, while the highest rates were observed at B = 0 degrees - H/D = 5.Öğe Elmas-Su Nanoakışkanı Kullanılan Kanatçıklı ve Farklı Yükseklikli Birleşik Jet Akışlı Kanallarda Yüzeylerin Soğutulması(Gazi Üniversitesi, 29.02.2024) Karabulut, Koray; Alnak, Doğan EnginÇarpan jet-çapraz akıştan oluşan birleşik jet etkisi elektronik elemanların soğutma performansını artırıcı bir etkiye sahiptir. Bu çalışmada, birleşik jet akışıyla kanatçıksız ve 30o açıya sahip kanatçıklı, N=2D kanatçık mesafeli ve H=3D ve 4D yükseklikli kanallarda su ve %2 hacimsel konsantrasyonlu Elmas-Su nanoakışkanı kullanılmasıyla küp ve yamuk modelli yüzeylerden olan ısı transferi ve performans analizi sayısal olarak incelenmiştir. Sayısal araştırma, sürekli ve üç boyutlu, k-ε türbülans modelli Ansys-Fluent programıyla gerçekleştirilmiştir. Literatürdeki çalışmalar gözetilerek kanal boyutlarına uygun olarak kanallara üçer adet model yerleştirilmiştir. Kanaldaki akışkanların Re sayısı aralığı 5000-9000’ dir. Sonuçlar, literatürdeki deneysel çalışmanın Nu sonuçlarıyla kıyaslanmış ve uyumlu oldukları belirlenmiştir. Çalışmanın sonuçları, kanallardaki her bir model için ortalama Nu sayısı ve yüzey sıcaklığının değişimleri olarak su ve nanoakışkan için kanatçıksız ve kanatçıklı durumlarda farklı kanal yüksekliklerinde karşılaştırmalı olarak incelenmiştir. Ayrıca, birleşik jet nanoakışkan akışının hız ve sıcaklık konturu dağılımları sunulmuştur. Bununla birlikte, kanallardaki her üç model yüzeyinin tümü için farklı Reynolds sayılarında performans değerlendirme sayıları (PEC) ve Re=7000 için ortalama Nu sayısı (Num) ve yüzey sıcaklık değerleri (Tm) değerlendirilmiştir. H=3D ve kanatçıklı kanalda Elmas-Su nanoakışkanının kullanılması kanatçıksız ve su akışkanı kullanılan kanala göre küp ve yamuk modelli yüzeylerde Num değerlerinin sırasıyla %24,14 ve %18,91 daha fazla olmasını sağlamıştır.Öğe Bakır Oksit-Su ve Elmas-Su Nanoakışkanlı Birleşik Jet Akışlı Kanallarda Isı Transferi ve Akış Yapılarının Değerlendirilmesi(Düzce Üniversitesi, 26.01.2024) Karabulut, KorayBu çalışmada, sabit 1000 W/m2 ısı akısına sahip dairesel oyuklu ve yamuk modelli bakır plakalı yüzeylerden olan ısı transferi ve birleşik jet akışlı kanallardaki akış yapıları su, %2 hacimsel konsantrasyonlu CuO-Su (Bakır oksit)-Su ve Elmas-Su nanoakışkanları kullanılarak sayısal olarak incelenmiştir. Sayısal çalışma, sürekli ve üç boyutlu olarak k-ε türbülans modelli Ansys-Fluent programının kullanılmasıyla gerçekleştirilmiştir. Kanallara ayrıca jet girişinden itibaren D jet giriş çapı ölçüsündeki sabit bir uzaklıkta (N) 45o ve 90o açılı kanatçıklar eklenmiştir. Kanal yüksekliği 3D iken; akışkanların Re sayısı aralığı 5000-15000’ dir. Çalışmadan elde edilen sonuçların doğruluğu ve kabul edilebilirliği deneysel araştırmalar sonucu elde edilen eşitlik kullanılarak kanıtlanmıştır. Çalışmanın sonuçları, kanallardaki her bir model için ortalama Nu sayısının değişimleri olarak su ve nanoakışkanlar için kanatçıksız ve kanatçıklı durumlarda karşılaştırmalı olarak değerlendirilmiştir. Ayrıca, CuO-Su nanoakışkanı için birleşik jet akışın hız ve sıcaklık konturu dağılımları farklı kanatçık açıları için sunulmuştur. Bununla birlikte, kanallardaki her üç desenli yüzeyin tümü için farklı Reynolds sayılarında performans değerlendirme sayıları (PEC) ve ortalama Nu sayısı (Num) ve yüzey sıcaklık değerleri (Tm) Re=5000 ve 15000 için analiz edilmiştir. Re=15000 için 90o kanatçıklı kanalda yamuk modelli yüzeyde sırasıyla Elmas-Su ve Bakır oksit-Su nanoakışkanları kullanılması durumları için kanatçıksız ve su akışkanı kullanılan kanallara göre Num sayısında %27,57 ve %26,11’ lik artışlar elde edilmiştir. Bunun yanı sıra, Re=15000 değerinde 90o açılı kanatçıklı kanallarda su akışkanı için PEC sayısı değerlerinin sırasıyla dairesel oyuklu ve yamuk modelli yüzeylerde Elmas-Su ve CuO-Su nanoakışkanlarına göre %1,1-%1,31 ve %0,82-%0,63 daha fazla oldukları tespit edilmiştir.Öğe The effects of rectangular baffle angles and heights on heat transfer and pressure drop performance in cross-triangular grooved rectangular flow ducts(Elsevier, FEB 2024) Karabulut, KorayThe improvements in heat exchangers mainly focus on rising energy efficiency. The cross-grooved rectangular flow ducts are largely used for plate heat exchangers. In this study, to enhance the heat transfer and hydraulic-thermal performance in the cross-grooved rectangular ducts with triangular grooves, rectangular baffles were located in the duct, and the influences of the rectangular baffle angles and heights on the features of the heat transfer and pressure drop were numerically analyzed in detail. The equations of Navier-Stokes and energy were solved by employing the Ansys-Fluent program with the k-ε turbulence model as steady and three-dimensional. Air used as working fluid has an inlet temperature of 293 K while the triangular groove’s wall temperature is 373 K. Rectangular baffles have various angles of 30°, 60°, and 90°, and heights of 0.25H, 0.5H, and 0.75H. The mean Nusselt number (Num), dimensionless temperature (T*), turbulence kinetic energy (TKE*), pressure (p*), and performance evaluation criterion (PEC) number of the ducts with rectangular baffles were evaluated by comparing with the cross-triangular grooved duct without baffle. Also, the contours of turbulence kinetic energy, temperature, and velocity vector were exhibited for the cross-triangular grooved rectangular ducts with different arrangements of baffle angles and heights. Results were matched with experimental and computational outcomes of the study found in the literature, and it was observed that they were fairly compatible. The increment rate of Num at 90° baffle angle and 0.75H height is 197.56 % higher for Re = 6000 compared to 0.25H. Besides, for Re = 1000, the PEC number is 84.50 % higher at 0.25H baffle height and 30° angle than at 90°.Öğe Investigation of Heat Transfer Increment in Electronic System Surfaces by Different Air Jet Impingement Applications(PLEIADES PUBLISHING INCPLEIADES HOUSE, 7 W 54 ST, NEW YORK, NY 10019, UNITED STATES, MAR 2024) Karabulut, Koray; Alnak, Doğan EnginThe impinging jet technique is a high-performance cooling technology for microchips which are basic elements of electronic systems and having high heat generation rates in small volumes. In this study, the improvement of heat transfer of the microchips used in all technological products today by air impinging jet has been examined. For this purpose, numerical research has been carried out on the cooling of copper plate surfaces with two different patterns, reverse triangle and reverse semi-circle shaped having 1000 W/m2 constant heat flux in rectangular cross-section ducts with adiabatic surfaces, by one and double air jets with distances of Dh and 2Dh between them. Numerical computation has been performed for energy and Navier-Stokes equations as steady and three-dimensional by employing the Ansys-Fluent computer program with the k-epsilon turbulence model. The obtained results have been compared with the numerical and experimental results of the study in the literature and it has been seen that they are compatible with each other. The results have been presented as the mean Nu number and the variation of surface temperature for each of both patterned surfaces in single and double jet channels with different distances. Streamline and temperature contour distributions of the jet flow along the channel for different H/Dh ratios and jet numbers have been evaluated for both patterned surfaces. In double-jet and 2Dh distance channels compared to Dh, at H/Dh = 12 and Re = 11,000, the Nu number increases of 67% and 65.9% have been observed on the first-row reverse triangle and semi-circular patterned surfaces, respectively.Öğe Heat transfer and thermal-hydraulic evaluations of cross-circular grooved rectangular flow ducts depending on rectangular baffle design parameters(SPRINGER HEIDELBERGTIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANY, MAR 7 2024) Karabulut, KorayThe cross-grooved rectangular flow ducts are largely used for plate heat exchangers. In this work, so as to better the heat transfer in cross-grooved rectangular ducts with circular grooves, rectangular baffles were located in the flow duct, and the influences of the rectangular baffle angles and heights on the features of heat transfer were numerically performed in detail. Equations of Navier–Stokes and energy were resolved by employing a program of Ansys-Fluent with k–ε turbulence model as steady and three-dimensional. Air employed as working fluid has a temperature of inlet 293 K while the circular groove’s wall temperature is 373 K. Rectangular baffles have various angles of 30°, 60°, and 90°, and heights of 0.25 H, 0.5 H, and 0.75 H. The mean Nusselt number (Num), temperature, turbulence kinetic energy (TKE), pressure, and PEC (Performance Evaluation Criterion) number of the flow duct with rectangular baffles were evaluated by comparing it with the cross-circular grooved channel non-baffle. Besides, the contours of velocity, turbulence kinetic energy, temperature, and velocity vector were exhibited for the cross-circular grooved rectangular channels with different baffle angles and height arrangements. Results were matched with experimental and numerical outcomes of the study found in the literature, and it was observed that they were fairly coherent. For Re 6000, the number of Num increases by 180.48% in the duct with a 90° angle and 0.75 H baffle height compared to the duct non-baffle, and for 30° baffle angle, the PEC value at 0.25 H baffle height is 66.88% higher than that in the 0.5 H.Öğe A new 1-D polymeric chains of (C5H6ClN2)[CdCl3H2O].H2O perovskite: Synthesis, Structure, Physico-Chemical Characteristics, theoretical calculations, and biological effects(elsevier, 24.07.2023) Hermi, Sabrine; Mrad, Mohamed Habib; Alotaibi, Abdullah A.; Tüzün,Burak; Bohme, Uwe; Alotaibi, Khalid M.; Hassan, Hamdy A.; Nasr, Cherif BenA novel 1D polymeric chains material (C5H6ClN2)[CdCl3H2O].H2O perovskite was successfully synthesized with the use slow evaporation process. According to the single-crystal X-ray diffraction, the structure was deduced to crystallize in the monoclinic system (space group P21/n, no 14), with the cell parameters a = 17.8596 (9) Å, b = 7.5766 (2) Å, c = 18.2245 (9) Å, and β = 95.068 (4)◦. The crystal packing is composed of infinite polymeric chains of ... .
