Atılım Academic Archive (Atılım University)
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Age replacement policies for discrete and continuous heterogeneous <i>k</i>-out-of-<i>n</i> systems
No full textEryilmaz, Serkan/0000-0002-2108-1781This paper studies age replacement policy for the k-out-of-n system that consists of independent but nonidentical components. Both continuously and discretely distributed components' lifetimes are considered. The failed components are replaced by new components and non-failed components are rejuvenated. Because the components are non-identical, the acquisition and rejuvenation costs of the components are chosen differently. The policy and the associated optimization problem are presented for general k and n, and 2-out-of-3 systems are studied in detail. The findings of the present paper extend the results in the literature from parallel systems to k-out-of-n systems.Science Citation Index Expande
Supply chain resilience in the tourism and hospitality industry: A comprehensive examination of driving and restraining forces
No full textBenli, Tolga/0000-0003-1028-8573Supply chain disruptions and a lack of resilient supply chains have adverse impact on the global economy. Particularly, complex nature of the tourism and hospitality industry makes it even more susceptible to failure when supply chain resiliency is rather low or does not exist. However, despite its significance, a comprehensive and systematic examination of building resilience in tourism and hospitality supply chains (THSCs) is lacking in the extant literature. The purpose of this study is to develop a comprehensive framework that outlines the driving and restraining forces for building resilient THSCs. The decision framework proposed in this study integrates rough interval valued neutrosophic (RIVN) force field theory of change with RIVN-ISM-MICMAC methodology. The results showed that the restraining forces, such as lack of effective regulations and incentives and effective organizational and supply chain policies are the primary factors that constrain improving resilience in THSCs. Theoretical and practical implications are discussed.Social Science Citation Inde
Design and Implementation of a Sampling System for Solid Flow on Conveyor Belts in Industry
No full textEndüstriyel üretim tesislerinde, üretilen malzemenin kalitesinin belirlenmesi çok büyük bir önem taşır. Malzemenin içeriğini ve kalitesini incelemek için yapılan iki tür yöntem vardır. Bu yöntemler fiziksel ve kimyasal analizlerdir. Tesislerin bu kalite kontrollerinin yapılabilmesi için bir takım test analiz laboratuvarları vardır. Bu laboratuvarlarda, üretilen her bir ürün için ham halinden başlayarak belirli aşamalarda numuneler alınır ve sonra testler ve analizler yapılır. Yapılan bu testler sırasında malzemenin içeriği ve kalitesi gözlemlenir. Test ve analizler sonucunda çıkarılan veriler tesislerin üretim kalitelerini arttırmalarına, üretim maliyetlerini düşürmelerine, enerji maliyetlerini düşürmelerine, doğru ürün üretimine katkıda bulunurlar ve böylece firmaların güvenilirliklerinin artmasını sağlarlar. Bu hususların gerçekleştirilebilmesi için üretim esnasında gerekli görülen her aşamada malzemeyi fiziksel ve kimyasal olarak tam temsil edebilecek şekilde numune alınmalıdır. Endüstride birçok türde numune alma teknikleri uygulanmaktadır. Bu aşamada, doğru numune alma noktasına, doğru tekniği uygulamak alınan numunenin tüm ürünü temsil etmesi açısından son derecede önemlidir. Bu çalışmada, gözlemler, teorik çalışmalar ve hesaplamalar sonrasında bir prototip üretilmiştir. Üretilmiş olan bu prototip üzerinde birçok test yapılmış ve yapılan bu testler sonrasında, kullanılması gereken parametreler kararlaştırılmıştır. Bu yeni numune alma makinesi ile çok daha iyi performansta çalışan, en az seviyede bakım isteyecek, alınan numunenin tüm ürünü tam temsil edebileceği bir numune alma sistemine ulaşılması hedeflenmiştir.In industrial production facilities, determining the quality of the produced material is of great importance. There are two types of methods to examine the content and quality of the material. These methods are physical and chemical analyses. The facilities have test analysis laboratories to perform these quality control processes. In these laboratories, starting from the raw state of each product,, samples are taken and then, tested and analyzed at certain stages. During these tests, the content and quality of the material are observed. The results of these tests and analyses contribute to the increasing of the production quality, to the reduction of production costs and energy costs, to the production of the desired products and therefore help increasing the reliability of companies. In order to achieve this, at each stage of the production phase, samples must be taken in such a way that can fully represent the material physically and chemically. There are many types of sampling techniques available in the industry. At this stage, applying the correct technique to the correct sampling point is extremely important to ensure that the sample taken represents the entire product. In this study, a prototype was produced after observations, theoretical studies and engineering calculations. Many tests were carried out on this prototype and after these tests, the parameters to be used were decided. With this new sampling machine, it is aimed to achieve a sampling system that works with a better performance, requires minimal maintenance whilst the sample taken can fully represent the entire product
Existence, Uniqueness and Successive Approximations for (λ, Ψ)-Hilfer Fractional Differential Equations
No full textThe focus of this paper is on investigating a particular type of nonlinear (lambda, psi)-Hilfer fractional differential equations, and analyzing their existence results. Our approach involves utilizing Banach's fixed point theorem, and we also explore the global convergence of successive approximations to provide additional insights into the topic. To further illustrate our findings, we provide some examples that supplement our main results.Science Citation Index Expande
Evaluating Anterior Segment Stability and Corneal Endothelium After Prolene Gonioscopy Assisted Transluminal Trabeculotomy (gatt) in Open-Angle Glaucoma
No full textAribas, Yavuz Kemal/0000-0001-5516-0747Introduction This study investigates the short-term effects of prolene gonioscopy-assisted transluminal trabeculotomy (GATT) on anterior segment parameters and corneal endothelium in patients with open-angle glaucoma. Methods This retrospective study included 30 eyes from 30 patients who underwent GATT surgery. Demographic data, ophthalmological examination findings, and intraocular pressure (IOP) measurements using a Goldman applanation tonometer were recorded. Scheimpflug images were acquired at the pre-operative stage, as well as on the 1st day, 1st week, and 1st month postoperatively. Corneal endothelial cell counts were obtained via specular microscopy. Results The mean age of patients was 60.3 +/- 15.5 years. Anterior chamber depth and central corneal thickness increased on the 1st postoperative day (p:0.002, p < 0.001, respectively). Changes in anterior chamber depth values at the postoperative 1st week and 1st month compared to baseline were not statistically significant. Central corneal thickness decreased significantly at the 1st postoperative month compared to baseline (p:0.007). Corneal endothelial cell counts at the 1st month were comparable to baseline values (p:0.936). Conclusion Our findings reveal that prolene gonioscopy-assisted transluminal trabeculotomy induces temporary changes in anterior segment parameters but preserves corneal endothelial cell count within the first month, suggesting a promising profile for GATT in glaucoma management.Science Citation Index Expande
An Investigation of Recycled Rubber Composites Reinforced With Micro Glass Bubbles: an Experimental and Numerical Approach
Get PDFRecycled rubber is widely used for its lightweight and cost-effective properties but often has limited mechanical strength, restricting its applications. This study enhances the mechanical performance of devulcanised recycled rubber by reinforcing it with micro glass bubbles (GBs) featuring a density of 0.65 g/cm(3) and an elastic modulus of 3.5 GPa, offering a high strength-to-density ratio. Uniaxial compression tests were conducted on samples with GB volume fractions of 5%, 10%, and 15%. Results were validated through finite element analysis (FEA) in ABAQUS/Standard, incorporating randomised GB distributions. A 2D representative volume element (RVE) with randomly distributed GBs was modelled, applying periodic boundary conditions to simplify the composite into an equivalent homogeneous material. Numerical simulations assessed the effects of GB diameters (30, 40, and 50 mu m) and inclusion size ranges (20-50 mu m and 10-60 mu m), finding minimal impact on results. The RVE, sized at 238 mu m, accurately represented macroscale composite behaviour. Stress-strain behaviour was analysed using average stress and strain tensors. The strong agreement between experimental and numerical results validates the proposed method, demonstrating its accuracy in predicting the mechanical behaviour of the reinforced composite material.Emerging Sources Citation Inde
Clinic-Oriented Injectable Smart Material for the Treatment of Diabetic Wounds: Coordinating the Release of Gm-Csf and Vegf
No full textBoyacioglu, Ozge/0000-0001-5240-8209Chronic wounds are often caused by diabetes and present a challenging clinical problem due to vascular problems leading to ischemia. This inhibits proper wound healing by delaying inflammatory responses and angiogenesis. To address this problem, we have developed injectable particle-loaded hydrogels which sequentially release Granulocyte-macrophage- colony-stimulating-factor (GM-CSF) and Vascular endothelial growth factor (VEGF) encapsulated in polycaprolactone-lecithin-geleol mono-diglyceride hybrid particles. GM-CSF promotes inflammation, while VEGF facilitates angiogenesis. The hybrid particles (200 -1000 nm) designed within the scope of the study can encapsulate the model proteins Bovine Serum Albumin 65 +/- 5 % and Lysozyme 77 +/- 10 % and can release stably for 21 days. In vivo tests and histological findings revealed that in the hydrogels containing GM-CSF/VEGF-loaded hybrid particles, wound depth decreased, inflammation phase increased, and fibrotic scar tissue decreased, while mature granulation tissue was formed on day 10. These findings confirm that the hybrid particles first initiate the inflammation phase by delivering GM-CSF, followed by VEGF, increasing the number of vascularization and thus increasing the healing rate of wounds. We emphasize the importance of multi-component and sequential release in wound healing and propose a unifying therapeutic strategy to sequentially deliver ligands targeting wound healing stages, which is very important in the treatment of the diabetic wounds.Science Citation Index Expande
Topographic Radioanatomical Analysis of the Singular Canal: Computed Tomography Study
No full textPurpose: The singular canal (SC) is where the singular nerve, a branch of the inferior vestibular nerve, which carries afferent information from the posterior semicircular canal (PSCC), passes and is important in the surgical approach of the presigmoid retrolabyrinthine. This study was carried out to evaluate the visibility of the SC on standard computed tomography (CT) images, its distance to the surrounding structures, and to investigate the variations of its anatomy and its relationship with the meatus acusticus internus.Materials and Methods: The study was carried out retrospectively using images of 194 temporal bones on temporal bone CT scans of 44 men and 53 women aged 18-65. In the study, various measurements were made, especially the presence of the SC, its length, its angle with the internal acoustic canal (IAC), and the distance between the internal acoustic pore (IAP) and the singular foramen. In addition, the presence of the high jugular bulb and PSCC dehiscence images were investigated.Results: The SC was detected in 85.1% of the analyzed images. The mean canal length was 3.93 +/- 1.22 mm, the angle between the SC and the IAC was 22.68 degrees +/- 3.60 degrees, and the distance between the SC and the IAP was 7.70 +/- 0.83 mm. While no difference was found between the sides, it was determined that the length and diameter of the SC did not differ according to gender.Conclusion: Detailed morphometric analysis of the SC and a thorough understanding of its relationship with the IAC, vestibulum, and PSCC will help to accurately define the posterior and lateral borders of the dissection for this region.Science Citation Index Expande
Effect of Aging Treatment on the Microstructure, Cracking Type and Crystallographic Texture of In939 Fabricated by Powder Bed Fusion-Laser Beam
No full textThis study aimed to provide a comprehensive understanding of how aging treatments (namely, HT1 and HT2) affect the microstructure, cracking behavior, and crystallographic texture of IN939 fabricated by powder bed fusion-laser beam (PBF-LB) method. Although both aged samples demonstrated similar grain structure and recrystallization behavior according to the electron backscatter diffraction (EBSD) analysis, as well as the precipitation of bimodal gamma ' phase and MC- and M23C6-type carbides, notable differences were observed in the size and morphology, particularly the gamma ' phase. The HT1 sample displayed coarsened primary gamma ' phase, with sizes reaching up to 2 mu m and exhibiting varied morphologies, including irregular and cuboidal shapes. Additionally, this treatment led to the formation of some gamma '-gamma eutectic regions and plate-like eta phase, along with the decomposition of MC-type carbides into M23C6-type carbides. In contrast, the HT2 sample displayed uniformly distributed spherical primary gamma ' phase with sizes ranging from 70 to 120 nm, accompanied by very fine secondary gamma ' phase. Furthermore, it was found that changes in both aged sample microstructures could result in the formation of strain-age cracks due to the gamma ' phase formation and liquation cracks due to the partial remelting of lower melting point phases. The findings also revealed that with the application of aging treatments, the hardness of the as-fabricated sample (339.8 +/- 3.4 HV) increased to 440.2 +/- 5.6 HV and 508.1 +/- 4.8 HV for the heat treatment of HT1 and HT2, respectively.Science Foundation Ireland (SFI) [16/RC/3872]; European Regional Development FundThis publication has emanated from research supported by a research grant from Science Foundation Ireland (SFI) under grant number 16/RC/3872 and is co-funded under the European Regional Development Fund.Science Citation Index Expande
Design and Development of an Automated Ussd-Based Mobile Payment System for Money Transfer Companies
No full textBu çalışmada para transfer şirketlerine yönelik otomatik bir USSD tabanlı mobil ödeme sistemi tasarlanmış ve geliştirilmiş ve bu sistemin etkilerinin incelenmesi amaçlanmıştır. Çalışma kapsamında otomatik USSD tabanlı mobil ödeme sisteminin finansal işlemler üzerindeki verimliliği, doğruluğu, kullanıcı deneyimi ve genel etkisi incelenmiştir. Nicel bir araştırma yaklaşımı kullanılan bu araştırmada 16 otantik katılımcıdan veri toplanmıştır. Veri toplama aracı olarak bu çalışma kapsamında geliştirilen bir form kullanılmıştır. Elde edilen bulgular, geleneksel sistemlerle karşılaştırıldığında mevcut sistemin işlem hızı ve doğruluğunun daha yüksek olduğunu ve kullanıcıların bu sistemden yüksek düzeyde memnuniyet duyduklarını ortaya koymaktadır. Araştırma aynı zamanda bu teknolojilerin uygulanmasındaki zorluklara ve fırsatlara da değinmekte ve bunların daha geniş finansal katılıma ve ekonomik kalkınmaya nasıl katkıda bulunabileceğine dair öneriler sunmaktadır. Çalışmanın sonuçları özellikle benzer ekonomik ve altyapısal bağlamlara sahip ülkeler için teknolojiden yararlanarak finansal sistemleri geliştirmeye yönelik bir model sunmaktadır.In this study, an automated USSD-based mobile payment system for money transfer companies was designed and developed and it was aimed to examine the effects of this system. Within the scope of the study, the efficiency, accuracy, user experience and overall impact of the automatic USSD-based mobile payment system on financial transactions were examined. In this study, which used a quantitative research approach, data was collected from 16 authentic participants. A form developed within the scope of this study was used as a data collection tool. The findings revealed that the processing speed and accuracy of the current system was higher compared to traditional systems and that users were highly satisfied with this system. The research also addresses the challenges and opportunities in implementing these technologies and offers recommendations on how they can contribute to broader financial inclusion and economic development. The results of the study provide a model for developing financial systems using technology, especially for countries with similar economic and infrastructural contexts