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Investigation of mechanical and interface behaviors of natural fiber reinforced polymer matrices
No full textKompozit malzemeler günümüzde hemen hemen tüm endüstriyel ve teknolojik alanlarda yaygın olarak kullanılmaktadır. Bu malzemeler ağırlıklı olarak sentetik elyaf takviyeleri ve termoset bazlı matris sistemleri kullanılarak üretilmektedir. Ancak termoset bazlı malzemelerin kürlendikten sonra geri dönüştürülemediği iyi bilinmektedir. Son yıllarda, sürdürülebilirlik ve çevresel etkinin azaltılması konusundaki küresel farkındalık, doğal elyaf takviyeli termoplastik kompozit malzemelere olan ilginin artmasına yol açmıştır. Bu ilgi, elektrikli araç pazarının genişlemesine paralel olarak bu tür malzemelere giderek daha fazla yönelen otomotiv endüstrisinde özellikle belirgindir. Bu tez kapsamında takviye elemanı olarak kenevir elyafı seçilirken, matris malzemesi olarak polipropilen iplik ve polipropilen granülleri kullanılmıştır. Polipropilen, hibrit iplik, kumaş ve granül formunda kullanılmış ve sıcak pres kalıplama yöntemi kullanılarak üç farklı kompozit plaka üretilmiştir. Elde edilen kompozit numuneler, ISO standartlarına uygun olarak üç nokta eğilme, Izod darbe, çekme ve darbeli delinme testlerine tabi tutulmuş ve elde edilen veriler buna göre analiz edilmiştir.Composite materials are widely used in almost all industrial and technological fields today. These materials are predominantly produced using synthetic fiber reinforcements and thermoset-based matrix systems. However, it is well known that thermoset-based materials are non-recyclable once cured. In recent years, global awareness of sustainability and the reduction of environmental impact has led to a growing interest in natural fiber-reinforced thermoplastic composite materials. This interest is particularly evident in the automotive industry, which is increasingly turning to such materials in parallel with the expansion of the electric vehicle market. In the scope of this thesis, hemp fiber was selected as the reinforcing element, while polypropylene yarn and polypropylene granules were used as the matrix material. Polypropylene was utilized in the form of hybrid yarn, fabric, and granules, and three different composite plates were produced using the hot press molding method. The resulting composite samples were subjected to three-point bending, Izod impact, tensile, and drop-weight impact tests in accordance with ISO standards, and the obtained data were analyzed accordingly.ELVİN TEKSTİ
Investigation of seam performance and biodegradability of organic cotton clothes for their sustaıinability
No full textIn recent years, it has become important for a sustainable environment that clothes are biodegradable, and that unused clothing does not pollute the environment by decomposing in nature. Cotton, especially organic cotton, can decompose very quickly in nature. Since organic clothing production has become important in recent years, the seam performance and biodegradability of these products, unlike conventional products, are important in creating new data for the textile and clothing industry. This paper presents an experimental study of the seam performance and biodegradability properties of organic clothes for their sustainability. In this study, six groups of fabrics with a plain weave structure were produced to examine the seam performance and biodegradability of clothes made of organic cotton woven fabrics. Each group includes three different samples of the fabric: conventional cotton fabric dyed with reactive dyes, organic cotton fabric dyed with reactive dyes, and organic cotton fabric dyed with natural dye. Therefore 18 samples having different properties were obtained. Fabric breaking strength, seam strength, seam efficiency and biodegradability tests of these fabric samples were determined. Sample women's blouses were sewn from the fabric samples used in the experimental study, and the blouse appearances were visually presented on the mannequin
Enhancing techno-mathematical literacy and ai self-efficacy in engineering education through artificial intelligence applications
No full textIn recent years, the rapid development of artificial intelligence technologies has been transforming the nature of engineering education and reshaping the skill sets expected from students. In this context, techno-mathematical literacy (TmL) stands out as a critical competence that enables engineering candidates to use both technology and mathematical thinking in an integrated manner. This study was conducted to examine the effect of artificial intelligence applications performed by engineering candidates on the development of their techno-mathematical literacy and to determine their self-efficacy levels regarding these applications. The study was designed with a quasi-experimental single group pre-test-post-test model from quantitative research approaches. The study group consists of 156 students, selected by simple random sampling method, studying in different programs at the engineering faculty of a state university. The data were collected with the Techno-Mathematical Literacy Scale (TMLS) and the Artificial Intelligence Self-Efficacy Scale (AILS). The data obtained from the pre-test and post-test applications were analysed with descriptive statistics, paired sample t-test, independent sample t-test, and ANOVA through SPSS 27 software. Also, the effect size was calculated. At the end of the six-week implementation process, it was found that artificial intelligence applications significantly increased the techno-mathematical literacy levels and artificial intelligence self-efficacy perceptions of engineering candidates. In addition, there was no significant difference in techno-mathematical literacy level and perception of artificial intelligence self-efficacy in terms of gender, but significant differences were found according to the department variable
Effect of aging and plasma nitriding on frequency-dependent fatigue behaviour of 17-4 ph stainless steel
No full textThis study investigated the effect of aging and plasma nitriding on frequency-dependent fatigue behaviour of 17-4 PH stainless steel. For this purpose, solution annealed, aged, and plasma nitrided specimens were compared in terms of microstructure, phase analysis, hardness, fatigue strength, and fracture surface. Aging of the 17-4 PH stainless steel was performed at 485 °C, and plasma nitriding was carried out at 390 and 450 °C for 36 h. Microstructural and phase analysis were performed using an optical microscope and X-ray diffraction (XRD). Hardness was measured by the Vickers method. The fatigue behaviour of the specimens was conducted using a rotating bending test under loading frequencies of 23.33 Hz and 46.67 Hz. The fracture surfaces were examined using a scanning electron microscope (SEM). The plasma nitrided specimens at 450 °C exhibited the highest core hardness (453 HV) and surface hardness (1069 HV), without exhibiting overaging in the core. Aging improved fatigue strength by more than 30%, and both nitriding and aging by more than 40%. Plasma nitriding shifted crack initiation beneath the surface, improving fatigue strength. The difference in fatigue strength between the loading frequencies for all specimens was found to be less than 5%, which is not significant. Cette étude a examiné l’effet du vieillissement et de la nitruration au plasma sur le comportement en fatigue en fonction de la fréquence, de l’acier inoxydable 17-4 PH. À cet effet, on a comparé des échantillons hypertrempés, vieillis et nitrurés au plasma en termes de microstructure, d’analyse de phase, de dureté, de résistance à la fatigue et de la surface de rupture. On a réalisé le vieillissement de l’acier inoxydable 17-4 PH à 485°C et l’on a effectué la nitruration au plasma à 390°C et 450°C pendant 36 heures. On a effectué l’analyse microstructurale et l’analyse de phase en utilisant un microscope optique et la diffraction des rayons X (DRX). On a mesuré la dureté par la méthode Vickers. On a étudié le comportement en fatigue des échantillons en utilisant un essai de flexion rotative sous des fréquences de chargement de 23.33 Hz et 46.67 Hz. On a examiné les surfaces de rupture à l’aide d’un MEB. Les échantillons nitrurés au plasma à 450°C présentaient la dureté du cœur (453 HV) et de surface (1069 HV) les plus élevées, sans survieillissement au cœur. Le vieillissement a amélioré la résistance à la fatigue de plus de 30%, et la combinaison de la nitruration et du vieillissement, de plus de 40%. La nitruration au plasma a déplacé l’initiation des fissures sous la surface, améliorant la résistance à la fatigue. Il s’est avéré que la différence de résistance à la fatigue entre les fréquences de chargement pour tous les échantillons était inférieure à 5%, ce qui n’est pas significatif
Relationship between optic nerve length and interoptic angle in the prediction of optic chiasm location
No full textIntroduction and objectives: The sellar region is an area in the base of the skull that is among the most common sites for tumors of the central nervous system. Surgical interventions are currently performed via different routes. While the optic chiasm occupies its expected position in 70% of the population, it can deviate from this position. In such cases, surgery involving this region becomes more difficult as the known surgical routes are narrowed. Advance awareness of these variations can help surgeons to identify the optimal route for safe surgical intervention in the sellar region. By performing simple measurements of both the lengths of the optic nerves and the angle between them, a surgeon can predict the location of the chiasm. Materials and methods: Twenty specimens collected from autopsies performed at Bursa Forensic Medicine İnstitute were examined to determine the optic chiasm types and the relationships between the surrounding subchiasmal structures. Results: Among the 20 specimens, we found two prefixed (10%), 10 normo-fixed (50%), and eight postfixed chiasms (40%). The mean interoptic angle was 81.03 (±17.41)⁰. Prefixed chiasms had angles in the range 115.36°–124.76 ° (mean 120.06 [±6.65]⁰), normo-fixed chiasm angles were between 83.11° and 97.53 ° (mean 86.07 [±6.73]⁰), and postfixed chiasms ranged between 53.01 ° and 78.71 ° (mean 69.20 [±9.13]⁰). The length of the right optic nerve ranged between 6.95 and 13.83 mm (mean 10.25 [±1.81] mm), and the length of the left between 7.25 and 12.51 mm (mean 10.40 [±1.47] mm). Obtuse angles indicated that the chiasm was prefixed, and acute angles were indicative of a postfixed chiasm. There was a strong negative correlation between optic nerve lengths and the interoptic angle; thus, as the length of the nerves increases, the interoptic angle becomes more acute. Conclusions: We have proposed a simple measurement of the optic nerve lengths and the angle between them to predict the relative location of the OC, which can be done easily on MRI
The role of personality traits and decision-making styles in career decision-making difficulties
No full textCareer decisions are one of the most important decisions individuals make in their lives. These decisions are multifaceted and complex, making them a challenging process, particularly for students. This creates obstacles for students navigating the career choice process. The aim of this study is to examine career decision-making difficulties within the framework of personality traits and decision-making styles. The target group of this study is undergraduate students studying at a public university. For this research, we collected data through online questionnaire forms. The questionnaire comprised demographic questions and three scales: career decision-making difficulties, personality traits, and decision-making styles. A total of 505 students (63.2% female) participated in the questionnaire. The research model was tested using path analysis. We also conducted network analysis in order to better understand and visualize the relationships between the sub-dimensions of the scales. The findings showed significant direct relationships between career decision-making difficulties and personality traits (conscientiousness, openness, neuroticism, and agreeableness) and decision-making styles (rational, dependent, avoidant, and spontaneous). According to the path analysis result, neurotic personality traits were positively correlated with career decision-making difficulties, while openness to experience, agreeableness, and conscientiousness were negatively correlated with them. The relationship between dependent, avoidant, and spontaneous decision-making styles and career decision-making difficulties was positive. These results provide valuable insights into the factors that shape career decisions, helping students make more informed choices and manage their career paths effectively
Fire risk analysis and fire safety design in historical sociocultural buildings
No full textWhile historical buildings play an important role in transferring the socio-cultural values of the period to future generations, fires cause the destruction of cultural sustainability.Aim The aim of the study is to determine the risks encountered in historical buildings and to determine the measures that can be taken.Method The checlist method prepared in accordance with the fire regulations in Turkey and the risk analysis method defined in NFPA 101 A were used together. In this study, fire risk analysis was evaluated on a sample historical theater building in Turkey.Results When the risk-reducing factors are evaluated according to NFPA101A and BYKHY; the locations and characteristics of the floor and vertical shafts in the BYKHY are ignored and not associated with fire risks. In the NFPA101A fire safety assessment system, only the access roads to the building are excluded from the risk analysis.Conclusion In order to reduce the risks in fire safety, the originality of the building should be left in the second place and the sources of ignition and flammable coatings should be located far away and the change of function to the spaces that pose a risk should be limited
Characteristics of pain in patients with nmosd and mogad: Impact on mental health, sleep and quality of life
No full textNeuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein-associated disease (MOGAD) are autoimmune disorders frequently accompanied by chronic, often neuropathic, pain, which significantly impacts the quality of life, sleep, and mental health. This study evaluated the incidence and characteristics of neuropathic pain in 106 patients with NMOSD or MOGAD and assessed its effects on mental health, sleep quality, and overall quality of life. Using clinical evaluation and MRI findings to localize lesions, pain classification revealed that chronic pain was more common in NMOSD patients (78.4%) than in MOGAD patients (52.7%), with a significant impact on both groups. Patients with MOGAD who experienced neuropathic pain reported notably poorer sleep quality and higher anxiety and depression levels. Pain severity was strongly associated with spinal cord lesion length and thoracic location, particularly in MOGAD patients. Current treatments provide insufficient pain relief, highlighting the need for more effective management strategies. This study emphasized that neuropathic pain substantially diminishes both physical and mental well-being in NMOSD and MOGAD patients, highlighting the importance of personalized pain management approaches to improve quality of life and mental health in these populations
Investigation of the effects of movement training and exergame applications on visual perception and hand-eye coordination skills in preschool children
No full textBu çalışmanın amacı; okul öncesi kademesinde eğitim gören çocuklara uygulanan 10 haftalık hareket eğitim programlarının ve exergame uygulamalarının çocukların görsel algı ve el-göz koordinasyon becerileri üzerine olan etkilerini incelemektir. Araştırmanın evrenini okul öncesinde yer alan öğrenciler oluşturmaktadır. Araştırmanın örneklemini ise Bursa’da yer alan milli eğitim bakanlığına bağlı Anaokulun’da öğrenim görmekte olan 32 öğrenci oluşturmaktadır. Deney grubunda yer alan öğrenciler hareket eğitimi ve exergame uygulamlarına katılmış kontrol grubunda yer alan öğrenciler ise sadece hareket eğitimine katılmışlardır. Çalışmada; öğrencinin yaşı, doğum tarihi, veli ad-soyad ve iletişim bilgilerini içeren kişisel bilgi formu, Granada Üniversitesi tarafından okul öncesi çocuklarının fiziksel uygunluğunu ölçmek ve değerlendirmek için oluşturulan ve geliştirilen, güvenirlik ve geçerlik çalışmalarını 2016’da Cristina Cadenas-Sanchez ve arkadaşları tarafından yapılan Preschool Physical Fitness (PREFIT) Test Bataryası, çocukların görsel algılama becerilerini değerlendirmek amacıyla Frostig (1961) tarafından geliştirilen ve Aral ve Bütün (2016) tarafından Türkçe’ye uyarlanan Frostig Görsel Algı Testi ve çocukların zihinsel gelişme düzeylerini ölçmek üzere, Arnold Gesell tarafından düzenlenen Evirgen ve arkadaşları tarafından güvenirlik çalışmaları yapılan Gessel Gelişim Testi kullanılmıştır. Verilerin normal dağılımı Shapiro- Wilk analizi ile test edilmiştir. Gruplar arası karşılaştırmalarda Bağımsız Örneklemler T Testi, Grup İçi karşılaştırmalarda Paired T Testi kullanılmıştır. Gerçekleştirilen analizler sonucunda 4x10 puanında deney grubunun lehine anlamlı farklılıklar bulunurken grup içi ön test ve son test puanlarına bakıldığında ve testin alt boyutları incelendiğinde, deney grubunda kontrol grubundan farklı olarak el kavrama becerilerinde anlamlı bir farklılık tespit edildiği görülmüştür. Deney grubunda uygulanan müdahalenin el kavrama becerisine olumlu anlamda etkisi olduğu sonucunu çıkartabiliriz. Her iki grupta da fiziksel uygunluk parametrelerinden 4x10 koşu performansı, boy, kilo ve uzun atlama becerilerinde artış görülmüştür. Deney grubuna uygulanan müdahalenin okul öncesinde yer alan çocukların mekânsal ilişkilerin algılanması becerisinde anlamlı derecede farklılık yarattığı görülmüştür. Aynı zamanda deney grubunda gerçekleştirilen müdahalenin çocukların görsel hafıza, el ve göz koordinasyonu ve ince motor becerilerini daha fazla geliştirdiği sonuçları elde edilmiştir.The aim of this study is to investigate the effects of a 10-week movement training program and exergame applications on the visual perception and hand-eye coordination skills of children attending preschool. The population of the study consists of students in preschool education. The sample includes 32 students studying at a kindergarten affiliated with the Ministry of National Education in Bursa. In the study, a personal information form containing the student's name, age, date of birth, parent's name, and contact information was used to obtain the demographic information of the student. The Preschool Physical Fitness (PREFIT) Test Battery, which was validated and tested for reliability by Sanchez and colleagues (2016), was used to measure and evaluate the physical fitness of children in the preschool level.The Frostig Visual Perception Test, developed by Frostig (1961) and adapted into Turkish by Aral and Bütün (2016), was used to assess visual perception skills. Additionally, the Gesell Developmental Test, organized by Arnold Gesell and validated by Evirgen et al. (2015), was used to measure the mental development levels of children. The normal distribution of the data was tested using the Shapiro-Wilk analysis. Independent Samples T-Test was used for comparisons between groups, and Paired T-Test was used for comparisons within groups. As a result of the analyses conducted, significant differences were found in favor of the experimental group in the 4x10 score. When examining the pre-test and post-test scores within the group and analyzing the sub-dimensions of the test, it was observed that there was a significant difference in handgrip skills in the experimental group compared to the control group. We can conclude that the intervention applied to the experimental group had a positive effect on handgrip skills. In both groups, an increase was observed in the physical fitness parameters, including 4x10 running performance, height, weight, and long jump skills. It was found that the intervention applied to the experimental group significantly affected the ability to perceive spatial relationships in preschool children. Additionally, the results indicated that the intervention carried out in the experimental group further improved children's visual memory, hand-eye coordination, and fine motor skills