Gaz Türbini Pallerindeki Akış Ayrılmasına İz Ve Pürüzlülük Etkilerinin DNS Yöntemiyle İncelenmesi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013Bu çalışmada, düşük-basınçlı gaz türbini pallerinin emme yüzeyindeki akışa benzer, düz bir levhada ters-basınç etkisiyle oluşan laminer ayrılma bölgesine, yüzey pürüzlülüğünün ve bir önceki kanadın ardizinin etkisi direk sayısal çözümleme yöntemi ile incelenmiştir. İz ve pürüzlülük etkilerinin birlikte incelendiği durum için alınan sonuçlara göre laminar ayrılma baloncuklarının boyutlarında düşüş olduğu görülmektedir. Fakat, bu iki etkinin sınır tabaka gelişimine etkisi iz ve pürüzlülüğün ayrı ayrı etkilerinin yanında ihmal edilecek kadar düşük kaldığı görülmektedir. Anahtar Kelimeler : Direk Sayısal Benzetim, Ters Basınç Gradyeni, Akış Kontrol, TürbülansIn this study, the combined effects of surface roughness and wake passing frequency to the laminar seperated region in a flat plate, similar to the suction side of the low pressure turbine blade, are investigated using Direct Numerical Simulation approach with adverse pressure gradient. For the case of the combined effects of surface roughness and wake passing frequency a decrease is observed in the size of the laminar separated bubble. However, the combined effects of the surface roughness and wake passing frequency to the development of the boundary layer is negligible compared to the individual effects of surface roughness and wake passing frequency. Keywords: Direct Numerical Simulation, Adverse Pressure Gradient, Flow Control, Turbulenc

Stress coupling between earthquakes in Northwest Turkey and the North Aegean Sea

Peer reviewe

CAST: Recent results & future outlook

Çetin, Serkant Ali (Dogus Author) -- Ezer, Cemile (Dogus Author) -- Yıldız, Süleyman Cenk (Dogus Author) -- Conference full title: 6th Patras Workshop on Axions, WIMPs and WISPs, PATRAS 2010; Zurich; Switzerland; 5 July 2010 through 9 July 2010.The CAST (CERN Axion Solar Telescope) experiment is searching for solar axions by their conversion into photons inside the magnet pipes of an LHC dipole. The analysis of data taken so far has shown no signal above the background, thus implying an upper limit to the axion-photon coupling of ga < 0.85 × 10-10GeV -1 at 95% CL for ma < 0.02 eV/c2. Ongoing measurements, with the magnet bores filled with a buffer gas (3He), are improving the sensitivity of the experiment for higher axion masses towards 1 eV/c2. Recent results, new ideas for Axion-Like Particle (WISPs) searches with CAST in the near future and the prospects of a new generation Helioscope are presented here

IL-6 and IL-1 beta responses to a carbohydrate-electrolyte drink in orienteering athletes

Background: This study was conducted to determine acute effects of carbohydrate-electrolyte (CHO-E) found in sports drinks, ingested just before an orienteering competition, on the levels of plasma IL-6 and IL-1 beta cytokine.Material and methods: The study was conducted in a randomized, double-blind design, including 23 elite orienteering athletes who volunteered to participate. Following the collection of resting specimens of blood, the experimental group (n = 12) was administered a sports drink containing CHO-E, while the placebo group (n = 11) was administered 500 ml of plain water. The subjects were asked to finish the orienteering competition.Result: IL-1 beta level in the 24th hour after the competition was found to be significantly lower than in precompetition and 2 hours after the competition in the placebo group (p 0.05).Conclusion: A drink containing CHO-E might have stopped muscle contraction-associated cytokine production by increasing the tissue stability of the muscles, compensating the loss of fluid and electrolytes from athletes' bodies

First principles modelling of magnesium titanium hydrides

Mixing Mg with Ti leads to a hydride Mg(x)Ti(1-x)H2 with markedly improved (de)hydrogenation properties for x < 0.8, as compared to MgH2. Optically, thin films of Mg(x)Ti(1-x)H2 have a black appearance, which is remarkable for a hydride material. In this paper we study the structure and stability of Mg(x)Ti(1-x)H2, x= 0-1 by first-principles calculations at the level of density functional theory. We give evidence for a fluorite to rutile phase transition at a critical composition x(c)= 0.8-0.9, which correlates with the experimentally observed sharp decrease in (de)hydrogenation rates at this composition. The densities of states of Mg(x)Ti(1-x)H2 have a peak at the Fermi level, composed of Ti d states. Disorder in the positions of the Ti atoms easily destroys the metallic plasma, however, which suppresses the optical reflection. Interband transitions result in a featureless optical absorption over a large energy range, causing the black appearance of Mg(x)Ti(1-x)H2.Comment: 22 pages, 9 figures, 4 table

Evaluating the effectiveness of agricultural adaptation to climate change in preindustrial society

The effectiveness of agricultural adaptation determines the vulnerability of this sector to climate change, particularly during the preindustrial era. However, this effectiveness has rarely been quantitatively evaluated, specifically at a large spatial and long-term scale. The present study covers this case of preindustrial society in AD 1500–1800. Given the absence of technological innovations in this time frame, agricultural production was chiefly augmented by cultivating more land (land input) and increasing labor input per land unit (labor input). Accordingly, these two methods are quantitatively examined. Statistical results show that within the study scale, land input is a more effective approach of mitigating climatic impact than labor input. Nonetheless, these observations collectively improve Boserup's theory from the perspective of a large spatial and long-term scale.postprin

Resistance to antiangiogenic therapy is directed by vascular phenotype, vessel stabilization, and maturation in malignant melanoma

Angiogenesis is not only dependent on endothelial cell invasion and proliferation, it also requires pericyte coverage of vascular sprouts for stabilization of vascular walls. Clinical efficacy of angiogenesis inhibitors targeting the vascular endothelial growth factor (VEGF) signaling pathway is still limited to date. We hypothesized that the level of vessel maturation is critically involved in the response to antiangiogenic therapies. To test this hypothesis, we evaluated the vascular network in spontaneously developing melanomas of MT/ret transgenic mice after using PTK787/ZK222584 for anti-VEGF therapy but also analyzed human melanoma metastases taken at clinical relapse in patients undergoing adjuvant treatment using bevacizumab. Both experimental settings showed that tumor vessels, which are resistant to anti-VEGF therapy, are characterized by enhanced vessel diameter and normalization of the vascular bed by coverage of mature pericytes and immunoreactivity for desmin, NG-2, platelet-derived growth factor receptor β, and the late-stage maturity marker α smooth muscle actin. Our findings emphasize that the level of mural cell differentiation and stabilization of the vascular wall significantly contribute to the response toward antiangiogenic therapy in melanoma. This study may be useful in paving the way toward a more rational development of second generation antiangiogenic combination therapies and in providing, for the first time, a murine model to study this

Vascular Wall-Resident CD44+ Multipotent Stem Cells Give Rise to Pericytes and Smooth Muscle Cells and Contribute to New Vessel Maturation

Here, we identify CD44(+)CD90(+)CD73(+)CD34(−)CD45(−) cells within the adult human arterial adventitia with properties of multipotency which were named vascular wall-resident multipotent stem cells (VW-MPSCs). VW-MPSCs exhibit typical mesenchymal stem cell characteristics including cell surface markers in immunostaining and flow cytometric analyses, and differentiation into adipocytes, chondrocytes and osteocytes under culture conditions. Particularly, TGFß1 stimulation up-regulates smooth muscle cell markers in VW-MPSCs. Using fluorescent cell labelling and co-localisation studies we show that VW-MPSCs differentiate to pericytes/smooth muscle cells which cover the wall of newly formed endothelial capillary-like structures in vitro. Co-implantation of EGFP-labelled VW-MPSCs and human umbilical vein endothelial cells into SCID mice subcutaneously via Matrigel results in new vessels formation which were covered by pericyte- or smooth muscle-like cells generated from implanted VW-MPSCs. Our results suggest that VW-MPSCs are of relevance for vascular morphogenesis, repair and self-renewal of vascular wall cells and for local capacity of neovascularization in disease processes