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Analysis of cascade vapor compression refrigeration system using nanorefrigerants: Energy, exergy, and environmental (3E)
No full textNanorefrigerants are considered the most efficient heat transfer fluids for improving heat transfer properties in the refrigeration and air conditioning equipment. For the first time in this study, energy, exergy, and environmental evaluation (3E) analyses were performed by the addition of different nanoparticles to a low GWP refrigerant pair such as R290/R1233ZDE in a cascade refrigeration system. CNT, CuO, and, TiO 2 nanoparticles were added to the refrigerant. The effect of nanoparticles on the cascade refrigeration system was analyzed using a model based on density changes. A detailed thermodynamic analysis was performed of the cascade refrigeration system at different evaporator temperatures and mass ratios. The power consumption of the compressor decreases as the evaporator temperature increases for all types of nanoparticles, resulting in an increase in COP values. The analyses showed that CuO nanoparticles had the highest performance. It has been observed that the energy and exergy efficiency increase as compressor work decreases with increasing mass ratios in all nanorefrigerants. In addition, the results indicated that all nanorefrigerants emit lower monthly CO 2 emissions compared to the pure refrigerants. The nanorefrigerants play a crucial role in reducing energy consumption and promoting environmental protection compared to traditional refrigerants
Ekonomik ve kültürel bağlam okuma başarısında önemli mi? Okuma başarısı ile ilişkili öğrenci, okul ve ülke düzeyi değişkenlerin incelenmesi
No full textBu araştırmada, dördüncü sınıf öğrencilerinin okuma başarısını etkileyen öğrenci, okul ve ülke faktörlerinin incelenmesi amaçlanmıştır. Bu doğrultuda PIRLS 2021’de yer alan veriler arasından öğrenci ve okul düzeyindeki değişkenler belirlenmiş ve bu değişkenlerle ilgili veriler analize dahil edilmiştir. Ayrıca, ülkelerin gelirlerinin bireylere dağılımları ile ilgili GINI, gayri safi milli hasılanın eğitime ayrılan yüzdesi (EDGDP) ve Hofstede’nin kültürel boyut teorisinden hareketle eğitimle ilişkili olan alt boyutlar da ülke düzeyinde değişkenler olarak ele alınmıştır. Ülke, okul ve öğrenci düzeyi ile ilgili çeşitli değişkenlerin okuma başarısıyla ilişkisini incelemek amaçlandığından araştırmada yöntem olarak ilişkisel tarama modeli benimsenmiş ve veriler hiyerarşik bir yapıda olduğu için istatistiksel analizlerde hiyerarşik lineer modelleme tekniği kullanılmıştır. Analizler sonucunda öğrenci düzeyi boyutunda öğrenci zorbalığı, okumayı sevme, kendinden emin okuma, öğrenme için ev kaynakları ve evdeki dijital araçlar değişkenlerinin okuma başarısını yordadığı bulgulanmıştır. Bu değişkenlere ilaveten okul düzeyinde değişkenlerin eklenmesi ile yapılan analizler sonucunda ise akademik başarı üzerine okulun etkisi ve okul disiplini değişkenlerinin okuma başarısını yordadığı tespit edilmiştir. Öğrenci ve okul düzeyi ile ilgili değişkenler eklenerek ülke düzeyinde ele alınan değişkenlerden de ülkelerin uzun dönem-kısa dönem ve belirsizlikten kaçınma düzeyleri okuma başarısını yordadığı belirlenmiştir
THE EFFECT OF TECHNOLOGY-BASED MATHEMATICS TEACHING ON MATHEMATICS PERFORMANCE: A SECOND-ORDER META-ANALYSIS
No full textIt is mentioned that all types of technological supports used in the mathematics instruction process have positive impacts on student mathematics performance without analyzing their educational dimension of them. In this context, the purpose of this research is to analyze the impact of technology-based mathematics instruction on the mathematics performance of students. 22 meta-analyses about the effects of technology-based mathematics instruction on student performance were carried out between 2017 and 2022; 27 impact sizes collected from these researches are combined with second-order meta-analyses. It is found that technology- based instruction’s impact on mathematics performance is medium-level. On the other hand, in studies about technology-based instruction, it is determined that the location and quality of the article caused important improvements in the mathematics performance of students. On the other hand, technology-based instruction, performance type, grade level, bias status, report type, and year range moderator variables didn’t cause statistical differences. It is determined that technology-based instruction methods increase the mathematics performance of students; however, Digital Tools Based Instruction and Software Based Instruction models are more efficient when compared to the other learning methods. Suggestions based on the research results are presented in the study
SOCIAL VISIBILITY OF CONSUMPTION AS A PHENOMENON DRIVING THE SELF-EXPRESSION AND TRAVEL INTENTION OF MUSLIM TOURISTS
No full textThis study aims to empirically predict the relationship between social visibility of consumption and word-of-mouth communication (e-WOM) and travel intention, with self-expression as the mediator variable. Survey data obtained from 483 tourists who follow the Halal Booking online travel agency on Facebook and Instagram was analyzed Structural Equation Modeling SEM. Results revealed that the social visibility of consumption among Muslim tourists positively affected self-expression (spiritual and social), e-WOM and travel intention. This research was able to promote ways on how social media can best promote travel destinations among Muslim travelers. © 2024 Editura Universitatii din Oradea. All rights reserved
The effect of social media marketing on word-of-mouth communication and purchase intention in food and beverage establishments: The mediating role of brand awareness
No full textLisansüstü Eğitim Enstitüsü, İşletme Ana Bilim Dalı, İşletme Bilim DalıBu araştırmanın amacı, yiyecek içecek işletmelerinde sosyal medya pazarlama aktivitelerinin ağızdan ağıza iletişim ve satın alma niyetine etkisinde marka farkındalığının aracılık rolünü incelemektir. Nicel araştırma yönteminin kullanıldığı araştırmanın evrenini, Türk menşeili yiyecek içecek işletmelerini Instagram üzerinden aktif olarak takip eden kullanıcılar oluşturmaktadır. Araştırmada kolayda örnekleme yöntemi kullanılmış ve araştırma verileri 511 katılımcıdan çevrimiçi anket yoluyla elde edilmiştir. Elde edilen verilerin analizi için SPSS 18.0 ve Yapısal Eşitlik Modellemesi (AMOS 24.0) kullanılmıştır. Analiz sonucunda, yiyecek içecek işletmelerinde sosyal medya pazarlama aktivitelerinin tüketicilerin ağızdan ağıza iletişimleri, satın alma niyeti ve marka farkındalığı üzerinde anlamlı bir etkiye sahip olduğu saptanmıştır. Ayrıca marka farkındalığının tüketicilerin ağızdan ağıza iletişimleri ve satın alma niyeti üzerinde anlamlı bir etkiye sahip olduğu belirlenmiştir. Son olarak, ağızdan ağıza iletişimin tüketicilerin satın alma niyeti üzerinde de anlamlı bir etkiye sahip olduğu saptanmıştır. Araştırmanın bir diğer önemli sonucu ise marka farkındalığının tüketicilerin satın alma niyetleri üzerinde aracılık etkisine sahip olduğudur.The purpose of this study is to examine the mediating role of brand awareness in the effect of social media marketing activities on word-of-mouth communication and purchase intention in food and beverage businesses. The population of the study, in which quantitative research method was used, consists of users who actively follow Turkish food and beverage businesses on Instagram. Convenience sampling method was used in the study and research data were obtained from 511 participants via online survey. SPSS 18.0 and Structural Equation Modelling (AMOS 24.0) were used to analyse the data obtained. As a result of the analysis, it was found that social media marketing activities in food and beverage businesses have a significant effect on consumers' word-of-mouth communication, purchase intention and brand awareness. In addition, brand awareness has a significant effect on consumers' word-of-mouth communication and purchase intention. Finally, word-of-mouth communication was also found to have a significant effect on consumers' purchase intention. Another important result of the study is that brand awareness has a mediating effect on consumers' purchase intentions
FR2/mmWave, N258 and N261 Bands, 5G Frequency-Compatible Ultra-Thin Metamaterial Absorber with Polarization Insensitivity for EMI shielding Applications
No full textSince adopting 5G technology, a notable rise in the prevalence of electromagnetic (EM) waves in the environment has become a significant concern. To reduce EM interference, broadband metamaterial absorbers offer an alternative solution for protecting devices in defense, communication, and healthcare applications, unlike their narrowband counterparts. This article presents a numerical investigation of an ultra-thin, polarization-insensitive metamaterial absorber (MMA) that uses metasurfaces and provides electromagnetic interference (EMI) reduction, covering the FR2/mmWave licensed N258 and N261 bands with an oblique incidence angle of up to 15 degrees. Comprehensive simulations are performed within the CST Studio Suite S2 2023 to examine the absorber's performance. Under normal incidence, the proposed MMA exhibits a wideband absorbency response exceeding 90% within the frequency range of 24.30-28.12 GHz. Moreover, the physical absorption mechanism is explained with electric and magnetic field distributions, including surface current distributions. Confirmation of the lack of mutual interaction among neighboring unit cells is established through testing with 1 x 2 and 2 x 2 arrays. An equivalent circuit model is also developed to confirm the EM simulation findings. The notable features of the proposed MMA make it an exceptional candidate for EM shielding applications, providing EMI reduction and covering the N258 and N261 bands. The developed metamaterial absorber, resulting in an ultra-thin, polarization insensitivity, and partially incidence angle insensitivity, achieves over 90% absorption within the supplementary 5G spectrum, covering the licensed bands N258 and N261. This absorber also provides effective EM interference (EMI) shielding against radiation from 5G base stations, ensuring the protection of sensitive equipment across diverse sectors, such as industry, research, and medical, addressing concerns related to security/privacy. imageBayburt University Scientific Research Projects Coordination Department [2023/69002-04]This research has been supported by the Bayburt University Scientific Research Projects Coordination Department. Project Number: 2023/69002-04
Characterisation of aluminum alloys by octopus fluidity test
No full textAim Determination of fluidity and tensile property characteristics of A206, A201 and A380 alloy with new octopus design Design & Methodology Melting and casting of alloys into sand moulds. Measurement of fluidity length and tensile properties Originality New fluidity test mould design where different cross section thicknesses are used to characterise the alloy properties Findings A356 has the lowest fluidity. A201 has lower fluidity compare to A206 but has the highest strength. A380 has similar characteristics with A201 Conclusion A380 can be an alternative choise for A201 alloy Declaration of Ethical Standards The authors of this article declare that the materials and methods used in this study do not require ethical committee permission and/or legal-special permission.Research Fund of the Istanbul Technical University [MOA-2019-42309]This work was supported by Research Fund of the Istanbul Technical University. Project Number MOA-2019-42309
Investigation of the consciousness and perception levels of secondary school 8th grade students about society scientific issues
No full textLisansüstü Eğitim Enstitüsü, Matematik ve Fen Bilimleri Eğitimi Ana Bilim Dalı, Fen Bilgisi Eğitimi Bilim DalıBu çalışmada, ortaokul 8. sınıf öğrencilerinin sosyobilimsel konular hakkındaki görüşleri ile bu konular hakkındaki bilinç ve algı düzeylerinin derinlemesine incelenmesi amaçlanmıştır. Araştırmada, nitel araştırma yöntemlerinden biri olan durum çalışması kullanılmıştır. Bu çalışma, Bayburt ili Merkez ilçesinde bulunan bir devlet okulunda öğrenim görmekte olan ortaokul öğrencileri ile gerçekleştirilmiştir. Çalışma grubu 2021-2022 eğitim öğretim yılının ikinci döneminde ortaokul 8. sınıfta öğrenim gören 46 öğrenciden oluşmaktadır. Veriler, araştırmacı tarafından geliştirilen sosyobilimsel konulara yönelik hazırlanan; Kelime İlişkilendirme Testi (KİT), Senaryo Tabanlı Anket Formu ve Yarı Yapılandırılmış Görüşme Formu ile toplanmıştır. Çalışmada yer alan sosyobilimsel konular; aşı, termik santral, uzay kirliliği, kan bağışı, kimya endüstrisi ve tarım ilacıdır. Öğrencilerden sosyobilimsel konularla ilgili altı anahtar kavramdan oluşan kelime ilişkilendirme testini doldurmaları istenmiştir. Test sonucunda elde edilen veriler kullanılarak frekans tablosu oluşturulmuştur. Bu frekans tablosuna göre öğrencilerin bilinç ve algı düzeylerini ortaya çıkaran kavram ağları çizilmiştir. Kavram ağlarından ortaya çıkan ilişkilere göre veriler analiz edilerek yorumlanmıştır. Çalışmanın sonucuna göre öğrencilerin verilen anahtar kavramlardan en çok aşı (242) ve kan bağışı (228) anahtar kavramlarını; en az ise uzay kirliliği (188) ve kimya endüstrisi (156) anahtar kavramlarını ilişkilendirdikleri görülmüştür. Senaryo tabanlı anket formundan elde edilen veriler, içerik analizi yöntemi ile analiz edilmiştir. Çalışmanın sonucuna göre çoğu öğrencinin; kan bağışı konusunda duyarlı oldukları, aşı konusunda farkındalıklarının olduğu, tarım ilacı kullanılmasına olumlu baktıkları ve termik santral kurulmasını destekledikleri belirlenmiştir. Ayrıca çoğu öğrencinin; boya fabrikası kurulumunu desteklemedikleri ve uzaya araç gönderilmesine olumsuz baktıkları belirlenmiştir. Son olarak 7 gönüllü öğrenci ile yarı yapılandırılmış görüşmeler yapılmıştır. Görüşmeler sonunda elde edilen veriler içerik analizi yöntemi ile çözümlenmiştir. Çalışma sonucuna göre, öğrencilerin günlük hayatta en çok karşılaştıkları sosyobilimsel konunun aşı olduğu görülmüştür. Ayrıca öğrencilerin sosyobilimsel konuların fen bilimleri dersindeki diğer konulardan farkını tanımlayabildikleri ve fen bilimleri derslerinde daha fazla sosyobilimsel konuların yer almasını istedikleri belirlenmiştir. Çalışmanın sonuçları doğrultusunda önerilerde bulunulmuştur.This study aimed to examine in depth the opinions of 8th grade secondary school students on socio-scientific issues and their levels of awareness and perception about these issues. In the research, case study, one of the qualitative research methods, was used. This study was conducted with secondary school students studying at a public school in the Central district of Bayburt province. The study group consists of 46 students studying in the 8th grade of secondary school in the second semester of the 2021-2022 academic year. The data were prepared for socio-scientific issues developed by the researcher; It was collected using the Word Association Test (WAT), Scenario-Based Survey Form and Semi-Structured Interview Form. Socio-scientific issues included in the study; vaccines, thermal power plants, space pollution, blood donation, chemical industry and pesticides. Students were asked to fill out a word association test consisting of six key concepts related to socio-scientific issues. A frequency table was created using the data obtained as a result of the test. According to this frequency table, concept networks that reveal the students' consciousness and perception levels are drawn. The data were analyzed and interpreted according to the relationships emerging from the concept networks. According to the results of the study, the most common key concepts given to students were vaccination (242) and blood donation (228); It was observed that they at least associated the key concepts of space pollution (188) and chemical industry (156). The data obtained from the scenario-based survey form was analyzed using the content analysis method. According to the results of the study, most students; It has been determined that they are sensitive about blood donation, have awareness about vaccination, have a positive view on the use of pesticides and support the establishment of a thermal power plant. In addition, most students; It has been determined that they do not support the establishment of a paint factory and have a negative view on sending vehicles into space. Finally, semi-structured interviews were conducted with 7 volunteer students. The data obtained at the end of the interviews were analyzed using the content analysis method. According to the results of the study, it was seen that the most common socio-scientific issue that students encounter in daily life is vaccination. It was also determined that students were able to identify the difference between socio-scientific issues and other subjects in science courses and that they wanted more socio-scientific subjects to be included in science courses. Suggestions were made in line with the results of the study
Investigation of The Effect of Molding Material Difference on Design in GGG70 Ductile Cast Iron Production
No full textThe casting process involves filling a prepared mould cavity with molten metal, which takes the shape of the container. While the liquid metal takes the shape of the container it is in, the method is attractive, while the volumetric changes during the liquid-solid transformation reveal the importance of moulding design for the manufacture of solid parts. Especially in cast irons, moulds with the same design may produce different results depending on the changing casting and foundry conditions because the volumetric change that occurs during the solidification of ductile cast irons is affected by many parameters and develops differently than in steel and aluminium castings. This study used model wet and resin molding materials to create single and double-riser moulding and castings with different section thicknesses. The importance of the type of mold material used in castings and the number of feeders for the robust production of the cast part was evaluated using experimental and modeling techniques. When the results were examined, it was seen that the shrinkage risk was lower with resin mould than with green sand moulding. In addition, depending on the riser connection point, the importance of the riser neck has emerged
The wound healing effect and DNA damage repair of exopolysaccharide extracted from Weissella cibaria MED17
No full textLactic acid bacteria can synthesize exopolysaccharides (EPSs), and some of these EPSs have pharmaceutical or medicinal properties. However, the wound healing capacities of EPSs have rarely been reported. In this study, EPS extracted from Weissella cibaria MED17 was used to investigate wound healing capacity. MED17 EPS was previously characterized and antioxidant capacity was also demonstrated. The application dose of the compound was determined by the MTT assay. The comet assay was applied to reveal the free radical scavenging activity and protection capacity of MED 17 against DNA damage by inducing oxidative stress and DNA damage with Mitomycin-C (MMC) in the cells. The comet assay showed that 15 mg/ml MED 17 EPS could ameliorate DNA damage by 50%. Moreover, the scratch test investigated the wound-healing effect of MED 17 EPS on HT-29 colon cells. MED 17 EPS could stimulate the migration of HT-29 and ameliorate MMC-induced DNA damage. However, further studies need to be conducted to clarify the mechanisms of the wound-healing process of MED 17.Baskent University Institutional Review Board [DA 22-25]; Baskent University Research Fund [TSA-2023-5314]; Yimath;ldimath;z Technical University Scientific Research Projects [TSA-2023-5314]This study was approved by the Baskent University Institutional Review Board (Project no: DA 22-25) and supported by the Baskent University Research Fund and also funded by Y & imath;ld & imath;z Technical University Scientific Research Projects (BAP) with the project number TSA-2023-5314. A part of the manuscript was presented in 11th International Molecular Biology and Biotechnology Congress