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Synergistic and Antagonistic Effects of Hybridization and MWCNT Reinforcement on the Solid Particle Erosion of Glass/Carbon Fiber Composites
No full textA systematic investigation into the solid particle erosion (SPE) of monolithic, sandwich-type hybrid and multi-scale (Multi Wallet Carbon Nanotube (MWCNT)-reinforced) glass/carbon fiber composites was performed confirming to the ASTM G76-18 standard, utilizing angular alumina erodent (similar to 600 mu m) at 34 m/s across key impingement angles of 30 degrees, 45 degrees, 60 degrees, and 90 degrees. The analysis reveals a profound performance dichotomy dictated by the governing wear mechanism. At the shear-dominated 30 degrees angle, where maximum material loss was observed, hybridization consistently enhanced erosion resistance relative to both monolithic benchmarks. This synergy, however, contrasts sharply with the nuanced behavior under the 90 degrees impact-dominant regime; here, although strategically hybridizing a brittle CFRP with tougher glass fibers reduced the erosion rate (ER) by a remarkable similar to 50%, this benefit was compromised by the matrix embrittlement induced by MWCNT incorporation. This work clarifies the difference between shear-dominated erosion in the ductile regime and fracture toughness under impact-dominated conditions
Data Augmentation for Text Classification Using Autoencoders
No full textDeep learning models have greatly improved various natural language processing tasks. However, their effectiveness depends on large data sets, which can be difficult to acquire. To mitigate this challenge, data augmentation techniques are employed to artificially expand the training data by generating synthetic samples. By enriching the dataset, data augmentation enhances model generalization, reduces overfitting, and improves model performance. This paper investigates the effectiveness of employing autoencoders for text data augmentation to enhance the performance of text classification models. The research compares four types of autoencoders which are Traditional Autoencoder (AE), Adversarial Autoencoder (AAE), Denoising Adversarial Autoencoder (DAAE), and Variational Autoencoder (VAE). Basic text preprocessing techniques, which are lowercasing, removal of non-alphanumeric characters and removal of stop words, are applied to all documents. Additionally, label-based filtering is applied, where the outputs of autoencoders that contradict the predictions of BERT are eliminated. The experiments are conducted using the SST-2 sentiment classification dataset, which consists of 7,791 training instances and 1,821 test instances. To better analyze the impact of data augmentation methods, experiments are also performed on smaller subsets of 100, 200, 400, and 1,000 instances. Data augmentation is applied at ratios of 1:1, 1:2 and 1:4 for these subsets. The results demonstrate that AE-based data augmentation methods, particularly at a 1:1 ratio, achieve better accuracy than the baseline models. This underscores the potential of autoencoders in improving text classification outcomes in NLP tasks
Deep Learning Based Dynamic UAV Positioning System Design
No full textMevcut İHA konumlandırma yöntemleri genellikle statik veya kural tabanlıdır, bu da değişen çevresel koşullara ve kullanıcı taleplerine hızlı bir şekilde yanıt verme yeteneklerini sınırlamaktadır. Bu tez çalışmasında, dinamik ortamlarda İnsansız Hava Araçları (İHA) için derin öğrenmeye dayalı dinamik bir konumlandırma sistemi geliştirilmesi amaçlanmaktadır. İHA kapsama alanını optimize etmek ve yanıt sürelerini iyileştirmek için bir Derin Öğrenme algoritması kullanılacaktır. Sistem, afet müdahalesi, gözetim ve iletişim ağları gibi dinamik adaptasyonun kritik öneme sahip olduğu senaryolarda etkili bir performans gösterecek şekilde tasarlanacaktır. Simülasyon ortamında geliştirilecek model, kullanıcı talepleri ve çevresel faktörlere dayalı olarak İHA'ların konumlarını gerçek zamanlı olarak sürekli optimize edecektir. Sistemin performansı, kapsama alanı genişliği, yanıt süresi ve dinamik koşullarda uyarlanabilirlik gibi kriterler üzerinden değerlendirilecektir. Bu araştırma, literatürdeki statik ve kural tabanlı yaklaşımların sınırlamalarını gidermeyi ve derin öğrenme teknikleri kullanarak daha etkili bir İHA konumlandırma sistemi sağlamayı hedeflemektedir.Existing UAV positioning methods are often static or rule-based, which limits their ability to respond quickly to changing environmental conditions and user demands. This thesis aims to develop a deep learning based dynamic positioning system for Unmanned Aerial Vehicles (UAVs) in dynamic environments. A Deep Learning algorithm will be used to optimize UAV coverage and improve response times. The system will be designed to perform effectively in scenarios where dynamic adaptation is critical, such as disaster response, surveillance and communication networks. The simulation model will continuously optimize the position of UAVs in real-time based on user demands and environmental factors. The performance of the system will be evaluated based on criteria such as coverage, response time and adaptability in dynamic conditions. This research aims to overcome the limitations of static and rule-based approaches in the literature and provide a more effective UAV positioning system using deep learning techniques
Evaluation Of Multiple Factors in Pediatricians‘ Antibiotic Selection
No full textObjective: The pediatrics department frequently uses antibiotics. Understanding factors influencing antibiotic prescribing can enhance treatment success. This study aimed to explore these factors, highlighting their role in antibiotic selection and overall treatment effectiveness. Material and Methods: Primary data was used in the study. The scope of the research consisted of pediatricians working in Konya province and its districts. The sample size of the research was calculated according to the snowball sampling method. The sample size started by selecting a pediatrician who met the research criteria, and other pediatricians were reached with the help of the selected pediatrician. The pediatrician was told to recommend someone or people with the same characteristics. Thus, 50 pediatricians were reached in the study by using the sampling method in question. In this study, the opinions of experts working in public institutions and organizations were taken to determine the multiple factors in pediatric physicians’ choice of antibiotics. The data obtained by the researchers by conducting a face-to-face survey of pediatricians on a voluntary basis was analyzed using the Entropy and TOPSIS method. Results: The first antibiotic agent preferred by the physicians was amoxicillin and clavulanic acid. While azithromycin was in the second place, clarithromycin was in the third place, the last two places were shared by cefdinir and cefixime. In the study, it was observed that the results obtained in terms of factors related to the physician and the parent were the same as the general results. While the results of drug-related factors, cost and reimbursement conditions were the same, azithromycin took the first place in these results. In all sub-solutions, the second-place option and the last two orders were the same. According to the sex of the physicians, the order of preferences of five male pediatric physicians was amoxicillin clavulanic acid > azithromycin > clarithromycin > cefdinir > cefixime, while 15 female physicians’ preferences were determined to be azithromycin > amoxicillin clavulanic acid > clarithromycin > cefdinir > cefixime. Azithromycin was preferred first. Conclusion: Multiple factors influence both diagnosis and treatment, affecting antibiotic selection and improving treatment success. © 2025 Elsevier B.V., All rights reserved.Selçuk Üniversitesi, S
Particle Swarm Optimization-Based Determination of Hydraulic Jump Location in Sluice Gate Flows
No full textThe hydraulic jump is a critical phenomenon in open channel hydraulics, and understanding its behavior is essential for the design and safety of hydraulic structures. In this study, 96 experiments were conducted using five different gate openings to model the location of hydraulic jumps in an open channel. The Particle Swarm Optimization (PSO) algorithm, a metaheuristic optimization technique, was employed to develop both linear and nonlinear predictive models. Experimental data from gate openings (e) of 2.5 cm, 3.5 cm, 4 cm, and 5 cm were used to train the models, while data from a e=6 cm gate opening were used for testing. The results demonstrated that the PSO algorithm effectively modeled the hydraulic jump location, yielding high accuracy and consistency with experimental observations. Model performance was evaluated using the Coefficient of Determination (R2), Nash-Sutcliffe Efficiency (NSE), and Mean Squared Error (MSE). The linear model outperformed the nonlinear model, achieving NSE = 0.954, R2 = 0.983, and MSE = 0.022. Furthermore, the upstream total head (H) and gate opening (e) were identified as the most influential parameters affecting the hydraulic jump location
A Study on Local People's Perception of Conservation in Protected Areas: The Case of Ihlara Valley
No full textThis thesis investigates how the coexistence of multiple conservation statuses in the Ihlara Valley impacts the local community's daily life, socio-cultural and economic activities, as well as their perceptions of and participation in conservation processes, by revealing the institutional and administrative challenges encountered in planning and conservation practices. Although conservation policies shaped within multi-actor governance models aim to ensure the sustainable protection of natural and cultural heritage, their implementation on the ground often gives rise to various socio-economic and managerial problems for local communities. In the case of the Ihlara Valley, the presence of overlapping conservation statuses complicates the establishment of administrative coherence due to fragmented planning processes, a lack of inter-institutional coordination, and ambiguous distributions of authority. This situation reduces the effectiveness of conservation practices and undermines the trust relationship between local residents and public institutions. Moreover, the legal and administrative restrictions imposed by these conservation statuses directly affect the traditional land-use practices and livelihood strategies of the local population, leading to transformations and tensions in their ways of life. Against this backdrop, this study aims to explore the knowledge levels of the Ihlara Valley's residents regarding the existing conservation statuses, their perceptions and attitudes toward conservation policies and planning processes, their degree of participation in decision-making mechanisms, and their assessments of the problems they encounter. Qualitative and quantitative data were collected through semi-structured in-depth interviews, surveys, and discussions with relevant institutional representatives, enabling a comprehensive analysis of the social dimensions of conservation processes. The findings indicate that the local community predominantly perceives conservation statuses as restrictive and exclusionary mechanisms. However, they also seek to benefit from these processes through alternative economic models such as ecotourism, sustainable agriculture, and cultural heritage-based entrepreneurship. Nevertheless, bureaucratic obstacles encountered during the implementation of conservation policies, uncertainties regarding property rights, and limited involvement in decision-making processes foster a critical distance between the community and conservation initiatives. By centering on the perceptions, attitudes, and expectations of the local population in multi-layered conservation areas, this thesis offers recommendations aimed at enhancing the social acceptability and administrative sustainability of conservation policies. Ultimately, the study aspires to inform the planning and management of similar natural and cultural heritage areas in Turkey, drawing on insights derived from the case of the Ihlara Valley.Bu tez çalışması, farklı koruma statülerinin bir arada bulunduğu Ihlara Vadisi'nde, planlama ve koruma süreçlerinde ortaya çıkan kurumsal ve yönetsel sorunların; yerel halkın günlük yaşamı, sosyo-kültürel ve ekonomik faaliyetleri ile koruma süreçlerine dair algı ve katılımı üzerindeki etkilerini ortaya koymayı amaçlamaktadır. Çok aktörlü yönetişim modelleri çerçevesinde şekillenen koruma politikaları, doğal ve kültürel mirasın sürdürülebilir şekilde korunmasını hedeflese de bu politikaların sahadaki uygulamaları çoğu zaman yerel topluluklar açısından çeşitli sosyo-ekonomik ve yönetsel sorunları da beraberinde getirmektedir. Ihlara Vadisi'nde bir arada bulunan farklı koruma statüleri, yetki paylaşımı, kurumlar arası eşgüdüm eksikliği ve planlama süreçlerindeki parçalanma nedeniyle yönetimsel bütünlüğün sağlanmasını güçleştirmekte; bu durum koruma uygulamalarının etkinliğini azaltarak yerel halk ile kamu kurumları arasındaki güven ilişkisini zedeleyebilmektedir. Ayrıca koruma statülerinin getirdiği hukuki ve idari kısıtlamalar, yerel halkın geleneksel arazi kullanımı ve geçim stratejileri üzerinde doğrudan etkiler yaratarak, toplulukların yaşam biçimlerinde dönüşümlere ve çeşitli gerilimlere yol açmaktadır. Bu bağlamda çalışma, Ihlara Vadisi'nde yaşayan yerel halkın koruma statülerine dair bilgi düzeylerini, koruma politikalarına ve planlama süreçlerine yönelik algı ve tutumlarını, karar alma mekanizmalarına katılım düzeylerini ve karşılaştıkları sorunlara ilişkin değerlendirmelerini ortaya koymak amacıyla yürütülmüştür. Araştırmada yarı yapılandırılmış derinlemesine görüşmeler, anket uygulamaları ve ilgili kurum temsilcileriyle yapılan görüşmeler aracılığıyla nitel ve nicel veriler toplanmış; böylece koruma süreçlerinin toplumsal boyutu kapsamlı şekilde analiz edilmiştir. Elde edilen bulgular, yerel halkın koruma statülerini çoğunlukla yaşamı kısıtlayan ve dışlayıcı mekanizmalar olarak algıladığını; ancak aynı zamanda ekoturizm, sürdürülebilir tarım ve kültürel miras temelli girişimler aracılığıyla bu süreçlerden fayda sağlama arayışında olduklarını göstermektedir. Bununla birlikte koruma politikalarının uygulanmasında yaşanan bürokratik engeller, mülkiyet haklarına ilişkin belirsizlikler ve karar alma süreçlerine sınırlı katılım, halkın koruma uygulamalarına yönelik eleştirel bir mesafe geliştirmesine yol açmaktadır. Bu tez, çoklu koruma statülerine sahip alanlarda yerel halkın algı, tutum ve beklentilerini merkeze alarak, koruma politikalarının toplumsal kabul edilebilirliği ile yönetsel sürdürülebilirliğine katkı sağlayacak öneriler sunmakta; Ihlara Vadisi örneği üzerinden elde edilen sonuçların, Türkiye'de benzer doğal ve kültürel miras alanlarının planlanması ve yönetimine yönelik politikalara yol gösterici olması hedeflenmektedir
Electrochemical Polymerization of O-Phenylenediamine in the Presence of Metal Salts: Influence of Cu(No3)2 and AgNo3 on Spectroelectrochemical Properties and Morphology
No full textIn this study, the effects of adding Cu(NOinf>3/inf>)inf>2/inf> and AgNOinf>3/inf> metal salts to the polymerization medium on the electrochemical and spectroelectrochemical properties of poly(o-phenylenediamine) (PoPD) were investigated. It was observed that the presence of Cu(NOinf>3/inf>)inf>2/inf> or AgNOinf>3/inf> during polymerization increased the rate of current peak growth, indicating an acceleration of the polymerization process in the presence of metal ions. The cyclic voltammetry responses of the metal/polymer composites differed significantly from those of the pure polymer, confirming the formation of metal/polymer composites. FTIR and UV–vis absorption spectra were analyzed to explore the chemical structure of PoPD, PoPD/Cu, and PoPD/Ag polymer films. SEM and AFM analyses revealed distinct morphological differences between the polymer synthesized in the presence of metal salts and the pure polymer. Spectroelectrochemical analyses demonstrated that the polymer films exhibited reversible color changes from light copper to green, with distinct optical intensities in the UV–vis spectra. The absorbance and current values changed reversibly with the applied potential, with response times of approximately 10 s. Colorimetric analysis based on the CIE system showed unique variations in brightness (L), magnitude (a), and intensity (b) for PoPD, PoPD/Ag, and PoPD/Cu, confirming distinct colorimetric shifts during redox transitions. This study highlights the impact of Cu and Ag salts on the spectroelectrochemical and electrochromic performance of PoPD, revealing potential applications for PoPD composites in advanced electrochromic devices. © 2025 Elsevier B.V., All rights reserved
Eco-Friendly Green Synthesis of Co3O4-NiO Nano Catalysts From Papaver Somniferum Biomass for Efficient NaBH4 Hydrolysis: Advancing Circular Bioeconomy and Clean Hydrogen Energy Conversion
No full textHydrogen generation via renewable and sustainable pathways is critical for clean energy transition and decarbonization efforts. In this study, we report the first-time development of a high-performance Co-Ni nanocatalyst synthesized through a green approach utilizing Papaver somniferum extract for efficient hydrogen generation via NaBH4 hydrolysis. The catalyst was comprehensively characterized using FTIR, XRD, FE-SEM/EDX, BET, TEM, and XPS, revealing its well-defined -morphological, structural, and compositional properties. The hydrogen generation rate (HGR) was optimized by systematically varying the catalyst loading, NaOH and NaBH4 concentrations, and reaction temperature. Under optimal conditions, the catalyst achieved a remarkable HGR of 2286.85 ml g(cat)(-1) min(-1) at 30 degrees C demonstrating superior catalytic efficiency compared to conventional Co-Ni catalysts. Kinetic analysis using the Langmuir-Hinshelwood model revealed an activation energy of 47.26 kJ mol(-1), a reaction rate order of 0.1 and an enthalpy change (Delta H) of -31.21 kJ mol(-1), highlighting the favorable thermodynamics of the reaction. FE-SEM analysis revealed a relatively uniform particle distribution, with an average size of similar to 200 nm and minimal agglomeration. The catalyst reusability studies demonstrated sustained activity over five consecutive cycles, confirming its long-term stability and practical viability for renewable hydrogen generation. These findings highlight the potential of green-synthesized nanocatalysts for sustainable hydrogen energy applications, particularly in fuel-cell technologies and hybrid renewable energy systems
Cyclic Oxidation Behavior and Protective Oxide Scale Formation in Stainless-Steel Alloys for High-Temperature Exhaust Valve Applications
No full textAs internal combustion engine (ICE) systems are increasingly exposed to severe thermal and oxidative environments, the oxidation resistance and structural integrity of exhaust valve materials have become critical for maintaining long-term engine reliability and efficiency. This study presents a comparative evaluation of the cyclic oxidation behavior of two candidate valve steels, 1.4718 (ferritic stainless steel) and 1.4871 (austenitic stainless steel), under service-temperature conditions. The specimens were exposed to repeated oxidation at 550 degrees C, 650 degrees C and 750 degrees C for 25 cycles in ambient air. The surface and cross-sectional morphologies of the oxide layers were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to investigate oxide scale composition, thickness, and growth characteristics. The oxidation behavior of both alloys proceeded in two distinct stages: an initial phase marked by accelerated oxidation, followed by a slower, more stable growth period. The extent of oxidation intensified with increasing temperature. The 1.4718 alloy developed relatively porous but compositionally stable oxide layers consisting primarily of Fe- and Cr-based spinels such as FeCr2O4 and Cr2SiO4. In contrast, the 1.4871 alloy formed a dense, adherent, dual-layered oxide scale composed of an outer Mn2O3-rich layer and an inner Cr2O3-rich layer, attributable to its high Mn and Cr content. The results underscore the critical influence of elemental composition, particularly Cr, Mn and Si, on oxide scale stability and spallation resistance, demonstrating the superior cyclic oxidation resistance of the 1.4871 alloy and its potential suitability for exhaust valve applications in thermally aggressive environments.Research Institute Supporting Program (RICSP-25-1), King Saud University, Riyadh, Saudi Arabia.King Saud University, Riyadh, Saudi Arabia; [RICSP-25-1
The Effect of Different Environmental Conditions on the Mechanical and Thermal Properties of Epoxy-Based Hybrid Composites
No full textIndustrial waste causes environmental problems in our country and around the world. It is believed that by evaluating these wastes in various areas, solutions can be found to address environmental pollution, and valuable inputs can be provided to the national economy. The high strength/density and elasticity modulus/density ratios of composite materials compared to traditional materials have increased the demand for these materials. Thermal pyrolysis of waste tires is an industrially valuable method for material and energy recovery, and pyrolytic carbon black (CB) is considered the secondary main product of this process. This study utilized natural waste eggshell (ChESh) powders containing pyrolytic carbon black (CB) and calcium carbonate as fillers in epoxy-based hybrid composites. The effects of both CB: ChESh ratio (1:1, 1:3, and 3:1 wt ratio) and different environmental environments (water, seawater, hydrothermal, and UV rays) on the mechanical, thermal, dynamic-mechanical, and UV ray resistance properties of composites containing 25% hybrid filler by mass were investigated. A scanning electron microscope (SEM), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), UV absorption, and tensile and hardness tests were used for the characterization of the composites. The maximum weight gain over 30 days in pure water, seawater, and hydrothermal aging conditions was found to be 0.99-1.4%, 0.86-1.18%, and 1.64-2.63% for ER and composites, respectively. In contrast to the unaged composite, the 1:3 hybrid composite had higher tensile strength values under these aging conditions. The mechanical properties were affected the most by hydrothermal aging. In addition, a lower decrease in the glass transition temperature (Tg) values was found for the aged 1:3 hybrid composite. This composite was the most resistant to UV radiation among the composites.Endüstriyel atıklar dünyada olduğu gibi ülkemizde de küçümsenemeyecek boyutlarda çevresel problemlere neden olmaktadır. Bu atıkların çeşitli alanlarda değerlendirilmesiyle çevre kirliliğine bir miktar çözüm sağlanabileceği gibi ülke ekonomisine de girdi sağlanacağı düşünülmektedir. Kompozit malzemelerin geleneksel malzemelerle karşılaştırıldığında dayanım/yoğunluk ve elastisite modülü/yoğunluk oranlarının yüksek olması bu malzemelere talebi arttırmıştır. Atık lastiklerin termal pirolizi, malzeme ve enerji geri kazanımı için endüstriyel açıdan faydalı bir yöntemdir ve pirolitik karbon siyahı (KS) bu sürecin ikincil ana ürünü olarak kabul edilir. Bu çalışmada, pirolitik KS ve kalsiyum karbonat içeren doğal atık malzeme-yumurta kabuğu (YK) tozları epoksi tabanlı hibrit kompozitlerde dolgu olarak kullanılmıştır. Kütlece %25 hibrit dolgu içeren kompozitlerin mekanik, termal, dinamik-mekanik ve UV ışınlarına dayanıklılık özelliklerine hem KS:YK oranının (kütlece 1:1, 1:3 ve 3:1), hem de farklı çevresel ortamların (su, deniz suyu, hidrotermal ve UV ışınları) etkisi incelenmiştir. Kompozitlerin karakterizasyonunda taramalı elektron mikroskobu (SEM), termogravimetrik analiz (TGA), dinamik-mekanik analiz (DMA), UV absorpsiyon, çekme ve sertlik testleri uygulanmıştır. Saf su, deniz suyu ve hidrotermal yaşlandırma koşullarında 30 gün boyunca maksimum ağırlık artışının ER ve kompozitler için %0,99-1,4, %0,86-1,18 ve %1,64-2,63 olduğu bulunmuştur. Yaşlandırılmamış kompozitin aksine, 1:3 hibrit kompozit bu yaşlandırma koşullarında daha yüksek çekme mukavemeti değerlerine sahip olmuştur. Mekanik özellikleri en fazla hidrotermal yaşlandırma etkilemiştir. Ayrıca, yaşlandırılmış 1:3 hibrit kompozit için camsı geçiş sıcaklığı (Tg) değerlerinde daha düşük bir azalma bulunmuştur. Bu kompozit, kompozitler arasında UV ışınlarına en dayanıklı tespit edilmiştir