Farklı En Boy Oranlarına Sahip Dikdörtgensel Prizmatik Cisimler Etrafındaki Akış Yapısının Deneysel Olarak İncelenmesi

Bu çalışmada, farklı en/boy oranlarına sahip dikdörtgenler prizması şeklindeki küt cisimler etrafındaki akış yapısı “parçacık görüntülemeli hız ölçüm tekniği” (PIV) ile deneysel olarak incelenmiştir. Çalışmada farklı en/boy oranlarında yatay kare prizma, küp, dik kare prizma şeklinde (sırasıyla H/L=0.5, H/L=1, H/L=2) akrilik malzemeden üretilmiş dikdörtgenler prizması şeklinde geometriler kullanılmıştır. PIV tekniği kullanılarak anlık olarak elde edilen hız vektörleri ile anlık girdap, akım çizgisi gibi bileşenler hesaplanmış, elde edilen verilere göre zaman ortalama hız değerleri, girdaplık değerleri, akım çizgileri ve hız profilleri belirlenmiştir. Deneylerde model boyutları, akış hızı, akışkanın yoğunluğu ve viskozitesi gibi parametrelere bağlı olarak Re sayısı 26000 olarak hesaplanmıştır. Çalışma sonucunda, incelenen geometrilerin sol üst köşesinde başlayan ve x ekseni boyunca uzanan bir hızlanma bölgesinin oluştuğu ve akış yönündeki hızın maksimum olduğu noktaların bu bölgede olduğu tespit edilmiştir. Dik olarak yerleştirilen H/L=2 (dik) prizmanın, diğer prizmalara göre (H/L=1 kübik ve H/L=0.5 yatay) geometri arkasında oluşan ölü alan bölgesini (≌ 2L) arttırdığı tespit edilmiştir

Thin layer drying of zucchini in solar dryer located in Osmaniye region

In this study, the dehydration behavior of zucchini using solar assisted drying system was examined according to 22 thin layer drying models available in literature. The correlation coefficient (R2), chi-square (χ2) and root mean square error (RMSE) values were calculated to check the suitability of models by non-linear regression analysis. It was found that Cubic and Modified Midilli-1 models were the most suitable equations and their R2 values were calculated as 0.99963. χ2 and RMSE values of related mathematical expressions were 1.89343×10‒5, 1.91692×10‒5 and 0.01685×10‒3, 0.01721×10‒3 respectively. In addition, heat transfer, mass transfer and diffusion coefficients, which were important parameters in design of drying systems were also determined as 5.18124 W/m2°C, 1.57129×10‒7 m/s and 2.335718×10‒9 m2/s respectively

The Analysıs Of Shell-And-Tube Heat Exchanger Usıng Computatıonal Fluıd Dynamıcs

Bu tez çalışmasında eriyik tuz (KNO3-NaNO2-NaNO3) kullanılan gövde borulu ısı değiştiricisinin ısı transfer performansı hesaplamalı akışkanlar dinamiği (HAD) programıyla analiz edilmiştir. Bu çalışma gövde tarafındaki akış üzerine yoğunlaşmıştır. Hesaplamalarda sıcaklık dağılımları, ısı akısı, ısı taşınım katsayısı ve Nusselt sayısı detaylı olarak incelenmiştir. Gövde borulu ısı değiştiricinin boru çapının ve boru sayısının ısı akısına, ısı transfer katsayısına ve Nusselt sayısına etkileri incelenmiştir. HAD analizlerinin sonuçları göz önünde bulundurularak Nusselt sayısı için bir analitik bağıntı elde edilmiştir. Sonuç olarak, bu çalışmada geliştirilen sayısal HAD modeli ısı değiştirici analizlerinde kullanılabilecektir.In this study, heat transfer performance of a shell and tube heat exchanger in which molten salt is used (KNO3-NaNO2-NaNO3) has been analysed by a computational fluid dynamic (CFD) programing. This study is focused on shell side flow phenomena. Temperature distributions, heat flux, heat transfer coefficient and Nusselt number have been investigated in the parametric studies. The effects of tube number and diameter of shell and tube heat exchanger on heat flux, heat transfer coefficient and Nusselt number were investigated. According to the results of the CFD analysis, an analytical correlation is obtained for the Nusselt number. As a result, developed numerical CFD models in this study can be used heat exchanger analysis in future studies

Towards A Comprehensive Simulator For Public Speaking Anxiety Treatment

Public speaking anxiety (PSA) is often cited as the most common social phobia. Virtual reality enables us to overcome PSA with life-like scenarios. This paper first reviews the state-of-the-art in virtual environments as an emerging treatment for public speaking anxiety and presents a comprehensive Virtual Environment (VE). In most of the studies there is a lack in the inclusion of physical and vocal cues. Physical and vocal cues generated by the audience are crucial contributors to PSA. We design a virtual auditorium with an audience exhibiting these physical and vocal cues; a comprehensive VE, helping overcome PSA. Additionally, participants are subjected to the three phases of speech: Anticipation, Performance and Recovery [Cornwell et al. in Biol Psychiatry 59(7):664–666, 2006 1]. The resulting simulator can then be used for training and eventual treatment of PSA in addition to being used as a tool for identifying cues to which speakers are more sensitive to

4-(3,4-dihydroxybenzoyloxymethyl)phenyl-O-β-D-glucopyranoside effect in liver regeneration

Following an injury or resection, the mammalian liver has the capacity to regain its former volume and functioning by restoring itself. Studies have demonstrated that antioxidants play a role in hepatic regeneration. This study investigated the effect of 4-(3,4- dihydroxybenzoyloxymethyl)phenyl-O-ß-D-glucopyranoside (PG) obtained from Origanum micranthum on liver regeneration. Sixty Wistar Albino rats were used. In the sham-operated group, a midline abdominal laparotomy was performed without hepatectomy. In the partial hepatectomy (PHx) group, the median and left lateral lobes were removed. Rats in the PHx group received 20 mg/kg/day PG intraperitoneally before being sacrificed at 24, 48, and 72 hrs, and 7 days later. Liver tissues were collected for immunohistochemical analysis and electron microscopic evaluation. We found an increase in mitotic index, and the numbers of Ki-67 stained hepatocytes in all PHx early stage groups (24 hr, 48hr, 72 hr), but not in 7-day groups. The regeneration mediators eNOS, iNOS, TNF-α and NF-kB were shown to increase in PHx groups. This increase was more prominent dependening on time. In the PHx treatment (PHx+PG) groups, while eNOS was still high, iNOS, TNF-α and NF-kB had decreased. The apoptotic index was markedly high in the PHx groups; this was prevented by PG treatment. These findings were supported by the ultrastructural results. Our findings indicate that PG supports liver regeneration, hepatocyte proliferation, reduced liver damage, and inflammatory mediators following PHx