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Hazır gı yı m tedarı k zı ncı rı nde tedarı kçı seçı mı ı çı n entegre temel bı leşen analı zı ve çok krı terlı karar verme yaklaşımı
No full textLisansüstü Eğitim Enstitüsü, Endüstri Mühendisliği Ana Bilim DalıTedarik zinciri yönetiminin önemli aşamalarından biri de tedarikçi seçimidir. Tedarikçi seçimi işletmelerin karşılaştığı en temel sorunlardan biridir. Günümüzde artan rekabet sebebiyle işletmeler tedarikçi seçimi problemlerine önem vermeye başlamıştır. Uzun vadede sürdürülebilir ilişkiler sağlamak için çeşitli çalışmalara odaklanmaktadırlar. Bu çalışma, hazır giyim sektöründe en uygun tedarikçiyi seçmek için hibrit bir yaklaşım sunmaktadır. Öncelikle kriter azaltmak için Temel Bileşenler Analizi (PCA) yöntemi uygulanmıştır. Daha sonra entropi ile kriter ağırlıkları hesaplanmıştır. Son olarak İdeal Sonuç Odaklı Çok Ölçütlü Karar Verme (TOPSIS) yöntemi ile kriterler sıralanmıştır. Sıralamaya göre en uygun tedarikçi seçilmiştir. Ağırlıklara bağlı olarak kriterlerdeki değişikliklerin etkisini değerlendirmek için duyarlılık analizi kullanılmıştır. Kriter azaltma yapılmadan EWM-TOPSIS ve Çok Kriterli Karar Verme İçin Karmaşık Sıralama (VIKOR) yöntemi ile karşılaştırılmıştır. Önerilen model ile hazır giyim üreticilerinin işletmeleri için birçok yönden daha uygun tedarikçiyi belirleme fırsatı sunacaktır.One of the important stages of Supply Chain Management (SCM) is supplier selection. SS is one of main problems encountered by businesses. Due to increasing competition today, businesses have begun to attach importance to SS problems. They focus on various studies to ensure sustainable relationships in the long term. This study presents a hybrid approach to selecting the most suitable supplier in the garment industry. First, the Principal Component Analysis (PCA) method was applied to reduce the criterion. Then, the criterion weights were calculated with entropy. Finally, the criteria were ranked with the Technique for Order Preference by Similarity to An Ideal Solution (TOPSIS) method. The most suitable supplier was selected according to the ranking. Sensitivity analysis was employed to assess the impact of criteria changes depending on the weights. It was compared with EWM-TOPSIS and VIseKriterijumsa Optimizacija I Kompromisno Resenje, Elimination and Choice Translating Reality (VIKOR) method without criteria reduction. The proposed model will provide the opportunity to determine a more suitable supplier in many aspects for businesses of garment manufacturers
The link between electricity consumption and stock market during the pandemic in Türkiye: a novel high-frequency approach
No full textThis article examines the relationship between electricity consumption and the stock market in the Turkish economy during the COVID-19 pandemic. A novel high-frequency model is used, incorporating the hourly energy consumption and Borsa Istanbul (BIST) National stock market index variables. To determine the effect of electricity consumption on the stock market index and vice versa, a high-frequency VAR-based spillover approach, time-varying Granger causality, and time-varying Bayesian VAR analysis are employed. The findings reveal a positive and weak relationship between electricity consumption and the stock market but it has a time-varying nature in an emerging market context in the post-COVID-19 period in the Turkish economy.Adana Alparslan Turkes Science and Technology UniversityNo Statement Availabl
Geniş giriş voltaj aralığına sahip DC-DC konvertörün taşınabilir ev aletlerinde uygulanması
No full textLisansüstü Eğitim Enstitüsü, Elektrik ve Elektronik Mühendisliği Ana Bilim Dalı, Elektrik Elektronik Mühendisliği Bilim DalıBu çalışmada geniş giriş voltaj aralığına sahip Zeta Konvertör'ün (ZK), çıkış voltajının istenilen seviyede sağlanmasındaki önemi ve uygulamalardaki performansı araştırılmıştır. Literatürde ZK'ün teorisi ve uygulaması üzerine az sayıda makale ve tez çalışmaları bulunmaktadır. Bu akademik kaynaklar arasında yapılan araştırmalarda, matematiksel denklemlerde ve ZK'ün devre eleman değerlerinin hesaplanmasında hatalara rastlanılmıştır. ZK'ün hem matematiksel teorisinin hem de uygulamasının literatürde detaylı olarak ilk kez bu tez çalışmasında sunulmuştur. MATLAB programının benzetim özelliği kullanılarak 5V–24V arasında giriş aralığına ve 12V çıkışa sahip bir ZK benzetim modeli önerilmiştir. ZK'ın çıkış voltajını istenilen seviyede sabit tutmak için Oransal-Inegral (OI) kontrol yöntemi kullanılmıştır. Elde edilen çıkış voltajı, sinüzoidal darbe-genişlik modülasyon (SDGM) yöntemi kullanılarak H-köprü evireç ile 12V alternatif gerilime dönüştürülmüş ve tek faz trafo kullanılarak gerilim seviyesi 220V değerine çıkarılmıştır. Tez kapsamında çeşitli benzetim durum çalışmaları sunulmuş ve bu çalışmaların sonuçlarında önerilen ZK'ün performansı değerlendirilmiştir.In this study, the importance and performance of the Zeta Converter (ZK) with a wide input voltage range in maintaining the output voltage at the desired level were investigated. In the literature, there are few articles and theses on the theory and application of ZK. During the research conducted among these academic sources, errors were found in the mathematical equations and in the calculation of the ZK circuit component values. This thesis presents, for the first time in detail, both the mathematical theory and the application of ZK in the literature. A ZK simulation model with an input range of 5V–24V and a 12V output was proposed using the simulation feature of MATLAB. A Proportional-Integral (PI) control method was employed to keep the output voltage of the ZK stable at the desired level. The obtained output voltage was converted to 12V alternating voltage using the H-bridge inverter with the Sinusoidal Pulse-Width Modulation (SPWM) method, and the voltage level was increased to 220V using a single-phase transformer. Various simulation case studies were presented within the scope of the thesis, and the performance of the proposed ZK was evaluated based on the results of these studies
Investigation of the cytotoxic activity of astaxanthin on glioblastoma cells
No full textFen Bilimleri Enstitüsü, Biyomühendislik Ana Bilim DalıGlioblastoma, beyin tümörlerinin en agresif ve zorlu formlarından birini temsil eder; hızlı ilerleyişi, invaziv doğası ve geleneksel tedavilere direnci ile karakterize edilir. Cerrahi, radyasyon ve kemoterapi gibi tedavi yöntemlerinde önemli ilerlemelere rağmen, glioblastoma hastalarının prognozu hala kötüdür ve genel sağkalım oranlarında sınırlı iyileşmeler vardır. Glioblastoma'nın kompleks moleküler ve hücresel heterojenliği, yüksek derecede infiltratif doğası ve bağışıklık gözetiminden kaçabilme yeteneği, etkili tedavi stratejileri geliştirmekte önemli zorluklar oluşturur. Astaxanthin, anti-inflamatuar, antioksidan ve antikanser etkileri de dahil olmak üzere çeşitli farmakolojik aktiviteleri nedeniyle dikkat çekmektedir. Astaksantinin umut verici terapötik potansiyeline rağmen, nispeten az sayıda çalışma özellikle glioblastoma hücreleri üzerinde sitotoksik aktivitesini araştırmıştır. Bu bağlamda, mevcut çalışmada, güçlü antioksidan özelliklere sahip doğal bir bileşik olan astakansantin Astaksantinin glioblastoma hücrelerine karşı tek başına ve kemoterpötik ilaçlarla (Etoposide) birlikte sierjistik sitotoksik aktivitesi araştırılmışdır.. Hücre canlılığı analizleri, koloni oluşumu deneyleri ve moleküler analizler gibi çeşitli in vitro deneylerin kombinasyonunu kullanarak, Astaksantinin glioblastoma hücrelerindeki sitotoksik etkilerinin ve altta yatan mekanizmalarının aydınlatılması ve Astaksantin ile etoposidin potansiyel sinerjistik etkilerini değerlendirmesi amaçlamıştur Ayrıca, bu çalışmada Astaksantinin anti mikrobiyal etkinliği araştırılmış lup bu dai alanda az sayıda çalışma yapılmış olmasından dolayı bir ek bakış açısı sunmaktadır. Bu çalışmanın bulguları, Astaksantin, etoposid ve bunların kombinasyonu ile doza bağlı olarak hücre canlılığında azalmaları göstermiştir, bulgular IC50 değerlendirmeleri tarafından desteklenmiştir. Astaksantin ve etoposid ayrıca U87MG hücrelerinde klonojenik potansiyeli inhibe etmiş ve morfolojik değişiklikler oluşturmuş, aynı zamanda survivin ve c-Myc'in düzeylerini düşürmüş ve Caspase-3 ekspresyonunu artırmıştır, bu da güçlü apoptotik etkileri işaret etmektedir. Ek olarak, Astaksantin Bacillus subtilis, Bacillus, Staphylococcus aureus ve Escherichia coli'ye karşı antimikrobiyal aktivite göstermiştir.Glioblastoma is well known among cancer cells to be one of the most formidable and highly proliferative forms of brain tumors. Despite the fact that there are numerous significant milestones in treatment that include chemotherapy, surgery, and radiation, its rapid progression , invasive nature and resistance to conventional therapies characteristics make it difficult to manage the spread of this disease and to enhance the several rates in total. In other words, glioblastoma is thought to have a very complex cellular and molecular heterogeneity coupled with highly infiltrative nature and ability to control immune system mechanisms which present obstacles in achieving suitable treatment approaches. Astaxanthin (ASX) has received much attention for its anticancer, antioxidant, anti-inflammatory, and anti-aging properties. However, the studies that explore the cytotoxic effects of ASX on glioblastoma cells remain poor. To address this gab, this study aims to investigate the cytotoxic potential of ASX against glioblastoma cells as a standalone treatment and in combination with the chemotherapeutic drug Etoposide. In order to perform this , a series of in vitro experiments that include cell viability tests, colony formation assays, and molecular analyses was done. Additionally, it was examined whether combining ASX with Etoposide enhances the cytotoxic effects against these cancer cell lines. Furthermore, this research further study the antimicrobial properties of ASX to expand our understanding of its potential applications as relatively few studies were conducted in this area. The findings of this study indicated dose-dependent reductions in cell viability with ASX, etoposide, and their combination, supported by IC50 assessments. ASX and etoposide also prevented clonogenic potential and caused morphological changes in U87MG cells, while downregulating survivin and c-Myc and upregulating Caspase-3 expression, indicating potent apoptotic effects. Moreover, the antimicrobial activity of ASX against Bacillus subtilis, Bacillus, Staphylococcus aureus, and Escherichia coli, was demonstrated suggesting further studies into its antimicrobial effectiveness and mechanisms of action. Overall, this thesis offers new perspective in the use of ASX in treating glioblastoma, highlighting its therapeutic potential importance as a natural substance with promising anticancer properties
Optimal Pencere Boyutu Yaklaşımı ile Endüstriyel Arıza Tespiti ve Sınıflandırması
No full text32nd IEEE Signal Processing and Communications Applications Conference (SIU) -- MAY 15-18, 2024 -- Tarsus Univ Campus, Mersin, TURKEYVarious important issues in industrial production processes such as product quality, process safety and supply continuity are diretly related to machine faults that occur in production and distribution stages. In addition to economic losses, machine faults also result in industrial accidents. Early diagnosis of possible faults would cut down possible losses. To date, various solutions on fault detection has been proposed. Existing solutions either detect faults after they occur or misdiagnose them due to complexity caused by operating over multiple measurements. In this study, to the best our knowledge, we propose a supervised model that optimally determines the window size for both fault detection and classification problems. Additionally, in order to determine the features that are more heavily related with the problem, we apply the binary version (BCS) of the nature-inspired Cuckoo Search Algorithm (CSA) for feature selection. Our results indicate that determining the window size appropriately has a significant impact on accuracy and feature selection increases the F-score roughly around 13%.IEEE,IEEE Turkey,Koluman & Berdan,Loodos,Figes,Turkcell,Yildirim Elec
Does hemimicelle concentration (HMC) coincide with critical aggregation concentration (CAC) in flotation?
No full textFlotation recoveries of oxide, silicate, and salt-type minerals when plotted against collector concentration exhibit a break point followed by a sharp increase. This threshold point called hemimicelle concentration (HMC) has been traditionally characterized by the formation of two-dimensional surfactant patches on the solid surface. The condensed phases have been identified by a variety of techniques since their inception in the early 1960s. Conversely, in another hypothesis, this breakthrough point was ascribed to surface precipitation of collector species on the mineral surface. Despite these controversies, a clear understanding of this issue has not been agreed upon. In fact, both occurrences are thermodynamically indistinguishable as they represent a similar property of surfactant deposition on the surface. In this context, the same researchers have stated that surface precipitation occurs way below the appearance of bulk precipitates. This issue of threshold point is a logical phenomenon and well documented in flotation literature. However, the alternatives discussed above have been usually taken for granted due to a lack of sufficient evidence. The objective of this paper is to present an alternative vision to the flotation literature. In this paper, we are proposing a third mechanism in which the threshold point is shown to correspond to the critical aggregation concentration (CAC) of particles in the bulk. Micro-flotation, zeta potential, and aggregation studies along with Fast-Cam recordings illustrate that aggregation of particles from this critical breakthrough point onward accelerates due to the formation of both hemimicelles and surface precipitates and particles undergo more intensive assemblage leading to higher flotation kinetics. The XDLVO calculations also confirm these findings.Scientific and Technological Research Council of Turkey (TUBITAK) [117M659]This study is supported by The Scientific and Technological Research Council of Turkey (TUBITAK) with Project Number 117M659
Askeri kara araçlarında kullanılacak yüksek gizlilik teknolojisine sahip gelişmiş radar soğurucu PANI/YIG/CB destekli kamuflaj boyasının incelenmesi
No full textLisansüstü Eğitim Enstitüsü, Nanoteknoloji ve Mühendislik Bilimleri Ana Bilim DalıGizlilik teknolojisi son yıllarda yoğun olarak çalışılan bir tür savunma teknolojisidir. Buradaki amaç hedef nesnenin radar kesit alanını (RCS) azaltarak radar görünürlüğünü engellemektir. Radar görünürlüğünü azaltmak için ya nesnenin geometrisi ile gelen elektromanyetik (EM) dalganın saçtırma ya da nesnede kullanılan malzemenin EM dalgaları soğurma özelliğine sahip olması gerekmektedir. Radar soğurucu malzemeler, dielektrik ve/veya manyetik kayıp mekanizması ile malzeme içerisine giren EM dalgaların enerjisini azaltarak hedef nesnenin radar görünürlüğünü azaltmaya çalışırlar. Bu tez çalışması kapsamında, radar soğurucu malzemeler üzerine kapsamlı bir çalışma gerçekleştirilmiştir. Mikrodalga soğurucu bir malzeme olan Y3Fe5O12 (kısa adı YIG) manyetik tozlar sol-jel yöntemi kullanılarak sentezlendi. Burada farklı ısıl işlem süreçleri uygulanarak yapı içerisinde ara yüzeyler oluşturuldu ve EM dalga soğurma karakteristikleri incelendi. Daha sonra, YIG ve karbon siyahı (CB) malzemeleri ile YIG1-x/CBx (0,00?x?1,00, 0,25 artışla) kompozitleri katıhal rekaisyon yöntemi ile üretildi. Üretilen kompozitlerin kristal yapıları, manyetik özellikleri ve EM dalga soğurma karakteristikleri incelendi. Son olarak bu kompozitlerin yüzeyleri iletken polimer olan polianilin ile yerinde polimerizasyon yöntemi ile kaplanarak PANI@YIG1-x/CBx (0,00?x?1,00, 0,25 artışla) hibrit kompozitleri sentezlendi. Hibrit kompozitlerin mikrodalga soğurma performanslarının tatmin edici düzeyde olduğu görülerek potansiyel askeri kara uygulamalarında kullanılabileceği görülmüştür. Anahtar Kelimeler: Elektromanyetik dalga soğurma, hibrit kompozit, karbon siyahı, radar soğurucu, YIG.Recently, stealth technology, which is a type of defense technology, has been studied intensively. The stealth technology aims to prevent radar visibility by reducing the radar cross section (RCS) of target object. To reduce radar visibility, the geometry of the object must either scatter the incoming electromagnetic (EM) wave or the material used in the object must have the ability to absorb EM waves. Radar absorbing materials try to decrease radar visibility of the target object by reducing the energy of EM waves entering the material through a dielectric and/or magnetic loss mechanism. Within the scope of this thesis, a comprehensive study on radar absorbing materials was carried out. Y3Fe5O12 (short name YIG) magnetic powders, a microwave absorbing material, were synthesized using the sol-gel method. Here, interfaces were created within the structure by applying different heat treatment processes and EM wave absorption characteristics were examined. Then, YIG1-x/CBx (0.00?x?1.00, 0.25 increment) composites with YIG and carbon black (CB) materials were produced via solid state reaction method. The structural and magnetic properties and EM wave absorption characteristics of the produced composites were examined. Finally, PANI@YIG1-x/CBx (0.00?x?1.00, 0.25 increment) hybrid composites were synthesized by coating the surfaces of these composites with the conductive polymer polyaniline by in-situ polymerization method. The microwave absorption performances of hybrid composites are at a satisfactory level and can be used in potential military land applications. Keywords: Electromagnetic wave absorption, hybrid composite, carbon black, radar absorber, YIG
Theoretical investigation of mixed-metal metal-organic frameworks as H2 adsorbents: insights from GCMC and DFT simulations
No full textMolecular hydrogen (H-2) is a renewable energy carrier, however, its practical applications are limited due to the challenges of developing safe and efficient H-2 storage devices. Metal Organic Frameworks (MOFs) containing at least two different metal ions in their structures are called as mixed-metal MOFs (MM-MOFs) and they could adsorb H-2 in higher amounts compared to structures containing single metal nodes. We theoretically examined the H-2 storage capacities of 26 MM-MOFs having various physical and chemical properties applying Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT) simulations. H-2 adsorption isotherms were calculated using a five-site anisotropic H-2 model. QIXSOG, YOMVIG, OSOYUR, Cu-Mg-BTC, Fe-Mg-BTC, and Cr-Mg-BTC were selected as top-performing MM-MOFs maximising H-2 adsorption gravimetrically and volumetrically at near-ambient conditions (233 K and 100 bar), approaching the DOE targets. YOMVIG has the largest H-2 adsorption enthalpy, calculated as -9.93kJ/mol at 233 K and 100 bar. DFT simulations have been conducted to analyse preferable H-2 adsorption sites as well as identify guest-host interactions. Electron density difference analysis showed that adsorbed H-2 molecules in the OSOYUR, Cr-Mg-BTC, Cu-Mg-BTC, and Fe-Mg-BTC are polarised. Our study challenges existing literature by identifying promising MM-MOFs as potential next-generation hydrogen storage adsorbents at near-ambient conditions.Scientific and Technological Research Council of Turkiye (TuBiTAK) [120Z160]Y.G acknowledges The Scientific and Technological Research Council of Turkiye (TuBiTAK) for funding through 1002 Short Term Support Module, grant agreement No: 120Z160. The calculations reported in this paper were performed using TRUBA computing resources, based in Turkiye
A Novel Triple-Band Microstrip Patch Antenna for Breast Cancer Detection Systems Fabricated with Recyclable Filaments
No full textBreast cancer ranks as the second most common cause of mortality among women globally, with the potential to increase survival rates by 97% through early detection. This study focuses on developing an innovative triple-band microstrip patch antenna designed to operate within the 2-6 GHz frequency spectrum. Simulation tests were conducted to evaluate its efficacy in early breast cancer detection. The antenna, constructed from copper tape and five different substrates (Felt, FR4, PET, PLA, TPU), was chosen considering its advantages for various applications. This design prioritizes wearer comfort while ensuring functionality and allows for producing antenna structures in desired geometries using 3D printing, even in complex configurations. With a general size of 30 x 30 mm2, the antenna underwent analyses on tumor-free models with tumors of different shapes and sizes, and additionally, to evaluate the performance of multiple antennas in detecting cancers, tumor models with 2 and 3 antenna numbers were analyzed in a total of six different breast scenarios. Critical performance parameters such as specific absorption rate (SAR), return loss (S11), and voltage standing wave ratio (VSWR) were obtained for each generated model. Simulation outcomes indicated SAR values within the permissible threshold for medical applications. Moreover, VSWR values maintained acceptability, while variations in return losses were contingent upon tumor dimensions, location, and the number of antennas used. Furthermore, the antenna's adaptability to bending was scrutinized through bending analyses, affirming its robustness, and sustained operational capability. One of the significant contributions of the study is the utilization of recyclable filaments such as PLA, TPU, and Protopasta in experimental investigations, providing a pathway for producing environmentally friendly and flexible antennas and breast phantoms. This study offers a way to develop more sensitive and reliable breast cancer screening and early diagnosis tools
L-proline determination by molecularly imprinted nanoparticles: A potential nanoscale tool for the diagnosis of metabolic disorders
No full textDetecting and quantifying amino acids is vital in biochemical analyses, especially for diagnosing metabolic disorders. L-proline, among these amino acids, holds significant relevance for various metabolic disorders in living organisms, particularly in humans. hyperprolinemia arises when ineffective breakdown of L-proline occurs due to enzyme deficiencies, leading to its accumulation in the body and underscoring the need for precise monitoring. To address this challenge, molecular imprinting offers a reliable single-step technique for detecting target molecules like proteins, peptides, amino acids, or ions with high selectivity. Moreover, nanoparticles, with significant surface area-to-volume ratios, enable high-level mass transfer and binding kinetics, making them ideal for nano-scale sensitive applications. In this study, 2-hydroxyethyl methacrylate-based molecularly imprinted nanoparticles were synthesized via mini-emulsion polymerization, combining the advantages of molecular imprinting technique and nanoparticles for the specific recognition of L-proline, and were well-characterized by Scanning Electron Microscopy, zeta-sizer particle size analysis, and Fourier Transform Infrared Spectroscopy. Based on zeta-sizer analysis, the estimated diameters of L-proline-imprinted and non-imprinted nanoparticles (Pro-MIPs and NIPs) were determined to be approximately 27.51 nm and 20.66 nm, respectively. The adsorption of L-proline onto nanoparticles from aqueous solutions was investigated in a batch system, and the maximum Lproline adsorption capacity was determined to be 26.58 mg/g for Pro-MIPs and 4.65 mg/g for and NIPs. The selectivity of Pro-MIPs was assessed using Liquid Chromatography-Tandem Mass Spectrometry, even in human serum and in the presence of competing molecules (L-histidine and L-phenylalanine). Additionally, Pro-MIPs maintained their adsorption capacity through up to 10 adsorption-desorption cycles without significant decrease.Scientific Research Projects Coordination Unit of Adana Alparslan Turkes Science and Technology University [21303015]The content of this article is based on the Master's thesis titled Designing of L-Proline specific nanoparticles for L-Proline detection from human serum, authored by Mustafa Nergiz, which was funded by the Scientific Research Projects Coordination Unit of Adana Alparslan Turkes Science and Technology University (Grant number: 21303015)