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Investigation of the Mechanical Properties of Composite Parts Produced Using a New Hybrid Manufacturing Technology
No full textThe production of composites with improved mechanical properties is an area of significant importance, with the aim of reducing production times and costs. In this study, a hybrid manufacturing technology was employed by combining FDM additive manufacturing technology with a vacuum-assisted injection method. Three-dimensional (3D) parts with a 10% infill rate were printed using FDM additive manufacturing technology and PLA material. The production parameters included the use of glass fibers with lengths of 2, 3, and 4 mm as well as epoxy, polyester, and polyurethane polymer resins. Accordingly, glass fiber-reinforced polymers (GFRP) were produced with varying production parameters. The mechanical properties of the 3D printed parts produced by FDM were improved by injecting the GFRP prepared into the hollow structures of the parts. Tensile and flexural testing and scanning electron microscopy analysis were conducted on the produced parts to determine the effects of the production parameters on their mechanical properties. The epoxy GFRP composite with 3 mm fiber length was found to exhibit the highest tensile strength of 25.30 MPa and the highest bending strength of 68.53 MPa. Maximum tensile and flexural strengths were achieved by all GFRP hybrid composites at a critical fiber length of 3 mm. The experimental results indicated that the epoxy GFRP composite demonstrated superior tensile and flexural strengths compared with the polyurethane GFRP and polyester GFRP composites
Effects Of Folic Acid Versus Nicotine On Bone Development
No full textPurpose: Nicotine exposure during pregnancy directly or indirectly harms not only the mother but also the fetal tissues. The aim of this study is to investigate the possible effects of folic acid given against nicotine used during pregnancy on bone development of fetuses. Materials and Methods: 18 adult female rats were divided into control, low-dose nicotine (LDN), high-dose nicotine (HDN), low-dose nicotine + folic acid (LDN + FA), high-dose nicotine + folic acid (HDN + FA), and folic acid (FA) group equally. During 20 days, 1 ml/kg serum physiologic (SP) solution to the control group, 3 mg/kg nicotine to LDN, 6 mg/kg nicotine to HDN, 3 mg/kg nicotine and 400 µg/kg FA to LDN+FA, 6 mg/kg nicotine and 400 µg/kg FA to HDN+FA, 400 µg/kg FA to the FA group was administered. Bones of fetuses taken by cesarean section on the 20th day of pregnancy were stained with the bilateral skeleton staining technique. The stained anterior and posterior extremity bones were photographed under a stereomicroscope. Bone length, extent of ossification and percentage of ossification were measured. Statistical data were evaluated using the R programming language (v. 3.2.3). Results: The bone development of LDN and HDN groups was significantly lower and LDN+FA and HDN+FA groups was close to the control group (p<0.05). Conclusion: While nicotine used during pregnancy decreases the bone development of fetuses, FA may decrease this effect and increase ossification
Electro-thermal dynamics in superconducting generators: An In-Depth investigation of AC losses and cooling techniques for a 10 MW rotor coil system
No full textIn the pursuit of optimizing superconducting generator systems, a comprehensive understanding of their electrothermal behaviors is crucial. This study builds upon previous research on an 8-pole, 10 MW superconducting generator by Inanir et al. (2022, Journal of Superconductivity and Novel Magnetism, 35(11), 3189) and focuses on an in-depth electro-thermal analysis of the rotor coil system. The emphasis is on assessing the AC losses experienced during transitory current changes. By simultaneously solving Ampere's equation and the heat conduction equation under specific boundary conditions, the research provides a detailed insight into the interaction between electrical and thermal dynamics within the rotor coils. The paper highlights the importance of temperature dynamics in various cooling and current conditions. The results demonstrate that achieving an optimal balance in cooling, particularly with the use of liquid nitrogen, is critical for efficient operation. This study not only advances the understanding of superconducting generators but also highlights potential strategies for improving their reliability and efficiency
The improvement rates in disc height and lordotic angle following anterior cervical discectomy and fusion with disc prosthesis
No full textAim: The objective of this study is to illustrate the impact of disc prosthesis instrumentation in the intervertebral disc space following discectomy on cervical lordosis (CL) as observed in radiographic images by measuring the Cobb angle and cervical disc height taken before and after surgery. Furthermore, the study seeks to evaluate the functionality of the disc prosthesis employed. The objective was to evaluate the functionality of the surgical procedure and the type of disc prosthesis employed. Materials and Methods: A total of 106 patients with cervical disc herniation who underwent surgical intervention using cervical disc prostheses were included in the study. Pre- and post-surgical lateral direct radiographic evaluations were obtained from each patient. The following variables were recorded for evaluation: preoperative Cobb angles, cervical disc height, surgical level, age, and gender. Results: The most frequent site of cervical disc operation was the C5-6 level. There was a significant increase in the cervical Cobb angle after surgery, as well as a significant increase in postoperative disc height in comparison to preoperative values. The change in Cobb angle and disc height was found to be statistically significant (p<0.05). Conclusion: A variety of cervical interbody grafts are currently in use. The use of cervical disc prostheses in cervical disc herniation surgery allows achieving optimum lordotic angulation. There is a continued need for new studies to support our physical examination findinds on the long-term clinical follow-up
Öğretmen Adaylarının Web 2.0 Araç Kullanım Yetkinlikleri ve Siber Aylaklık Eğilimleri Arasındaki İlişki
No full textBu çalışmanın amacı, öğretmen adaylarının web 2. Araçları kullanım yetkinlikleri ile siber aylaklık etkinlikleri arasındaki ilişkiyi ve bu değişkenlerin bazı demografik özelliklere göre ayrışma durumlarının araştırılmasıdır. Bu amaç doğrultusunda 2023-2024 eğitim-öğretim yılında lisans düzeyinde eğitim fakültesinde öğrenim gören 259’u kadın (%74) 91’i erkek (%26) olmak üzere toplam 350 öğretmen adayı ile yürütülmüştür. Veri toplama aracı olarak “Web 2.0 Araçları Kullanım Yetkinliği Ölçeği” ve “Siber Aylaklık Etkinlikleri Ölçeği” kullanılmıştır. Çalışma bulgularına göre web 2.0 araçları kullanım yetkinliği ile siber aylaklık etkinlikleri arasında negatif yönlü düşük düzeyde bir ilişki saptanmıştır
TÜRKİYE’DE İNSAN KAYNAKLARI YÖNETİMİ ALANINDA YAZILMIŞ LİSANSÜSTÜ TEZLERİN İÇERİK ANALİZİ
No full textBu araştırmada, insan kaynakları yönetimi konusunda güncel yönelimi belirlemek ve bunun sonucunda ileride yapılacak araştırmaların ne yönde olacağını saptamak için Türkiye’de 2023 yılında insan kaynakları yönetimi konusunda yazılmış lisansüstü tezler betimsel içerik analizi kullanılarak incelenmiştir. Bu yönde, Yükseköğretim Kurumu Ulusal Tez Merkezi veri tabanında tarama yapılmış ve 2023 yılında yazılan 55 adet doktora ve yüksek lisans tezi analiz edilmiştir. Analizler Maxqda 18 nitel veri analiz programı kullanılarak yapılmıştır. Analiz edilen tezlerin 16’sı doktora, 39’u yüksek lisans seviyesindedir. Bulgulara göre, doktora ve yüksek lisans tezlerinde daha çok nicel yöntem kullanılmıştır. Tezlerde anahtar kelime olarak en fazla kullanılan “insan kaynakları yönetimi/uygulamaları’’dır. Doktora tezi en çok Sosyal Bilimler Enstitüsü bünyesinde, yüksek lisans tezi ise Lisansüstü Eğitim Enstitüsü’nde tamamlanmıştır. Ayrıca doktora tezleri ile yüksek lisans tezlerinin arasında enstitü, ana bilim dalı ve konu açısından bazı farklılıkların olduğu saptanmıştır
Immediate effects of manual therapy on respiratory functions in healthy young individuals: a randomized controlled trial
No full textThis study aimed to investigate the immediate effects of manual therapy (MT) on the respiratory functions of healthy young individuals. The study included 104 participants, consisting of university students (87 females, 17 males, mean age 20.1 +/- 2.2). Participants were randomly assigned to the MT (experimental; n = 52) and sham-MT (control; n = 52) groups. The experimental group underwent thoracic manipulations and mobilizations along with diaphragm mobilization. In the control group, the hands were placed on the same regions, but no specific intervention was applied. All participants underwent respiratory function testing before and after the intervention using a portable spirometer (PEF- Peak expiratory flow; FEV 1- Forced expiratory volume in 1 s; FVC- Forced vital capacity and FEV1/FVC- Tiffeneau index). In the experimental group, there was a significant increase in the mean PEF value following MT application from 296.3 +/- 110.8 to 316.1 +/- 119.1 (p = 0.018). Conversely, the mean PEF value in the control group showed a slight decrease from 337.1 +/- 93.3 to 324.5 +/- 89.2 (p = 0.002). No significant changes were observed in FVC, FEV1, or FEV1/FVC values pre- and post-intervention in either groups. A single MT session led to a significant improvement in PEF in healthy young individuals. Further research is needed to explore the long-term effects of MT on respiratory functions and its potential implications in clinical practice.Trial registration ClinicalTrials.gov: NCT05934240 (06/07/2023)
Ses Kirliliği Konusunun Eğitsel Oyun Yoluyla Öğretimi
No full textEğitim ortamlarında oyunlar bireyin öğrenmesini kolaylaştırmak için kullanılmaktadır. Öğretimi amaçlayan oyunlar eğitsel oyun olarak ifade edilmektedir. Bu çalışmada ilkokul dördüncü sınıf öğrencilerine eğitsel oyunla ses kirliliği konusunun öğretimi gerçekleştirilerek onların farkındalıkları ve bilgi düzeylerinin artırılması amaçlanmıştır. Nitel araştırma yaklaşımı çerçevesinde olgubilim deseninde yürütülen araştırmanın çalışma grubu, ölçüt örnekleme yöntemi ile belirlenmiştir. Çalışma grubu 2022-2023 eğitim öğretim yılı ikinci döneminde, Amasya ilinin Suluova ilçesinde yer alan bir devlet ilkokulunun dördüncü sınıfında öğrenim gören 13 öğrenciden oluşmaktadır. Araştırma verileri araştırmacılar tarafından geliştirilen yarı yapılandırılmış görüşme formu kullanılarak toplanmıştır. Görüşme verileri betimleyici analiz ile çözümlenmiştir. Verilerden öğrencilerin çalışma için geliştirilen ‘Ses Ver, Sus’ isimli eğitsel oyununu olumlu kavramlarla ilişkilendirdikleri belirlenmiştir. Ayrıca öğrencilerin oyununun kurallarını rahatlıkla kavrayabildikleri ve oynayabildikleri belirlenmiştir. Araştırma sonunda ‘Ses Ver, Sus’ oyununun ses kirliliği konusunun öğretimine öğrencilerin anlamasına katkı sağladığı sonucuna ulaşılmıştır
Reconstruction of a pre-service teacher reflection through objective hermeneutics
No full text[No abstract available
Reducing the cost of electricity storage with a novel solar thermal support scenario in pumped thermal energy storage (PTES)
No full textPumped Thermal Electricity Storage (PTES) is a system that allows the conversion of electrical energy into thermal energy and its more cost-effective storage. Thermal integration is one of the methods applied to increase the round-trip efficiency (?rt) of PTES. The disadvantage of TI-PTES systems that use solar energy as a heat source is the need to store hot water with an additional heat storage system due to fluctuations in solar energy. Additional heat storage system significantly increases the cost of energy storage. In this study, a novel solar thermal integration scenario was presented. The novelty in the study has been utilizing the same water tanks for both the thermal storage of electricity and thermal support. Thermal support for PTES was provided by a concentration photovoltaic thermal (CPVT) system. Thus, it was aimed to reduce additional heat storage costs. With the proposed design (STI(CPVT)-PTES), the power supplied to the compressor (?COMP) and round-trip efficiency varied in the range of 0.52–2.6 MW and 41.1–128.3 %, respectively. The overall exergy efficiency of the system varied between 19 % and 42 % depending on solar energy, sunshine duration, and parameter values. The parameter that most economically affected the system was the mass flow rate of the heat source (?hs), and the lowest levelized cost of storage (LCOS) was obtained as 0.227 $kWh?1 at a ?hs of 250 kg/s. With STI(CPVT)-PTES, a reduction in LCOS ranging from 1.3 % to 33.2 % was achieved compared to other thermal integration scenarios. Analysis results revealed that the proposed system has a high potential to be an alternative to other thermally integrated PTES systems. © 2023 Elsevier Lt