1,020 research outputs found
Influence of Turbulence Model for Wind Turbine Simulation in Low Reynolds Number
In designing a wind turbine, the validation of the mathematical model’s result is normally carried out by comparison with wind tunnel experiment data. However, the Reynolds number of the wind tunnel experiment is low, and the flow does not match fully developed turbulence on the leading edge of a wind turbine blade. Therefore, the transition area from laminar to turbulent flow becomes wide under these conditions, and the separation point is difficult to predict using turbulence models. The prediction precision decreases dramatically when working with tip speed ratios less than the maximum power point. This study carries out a steadiness calculation with turbulence model and an unsteadiness calculation with laminar model for a three-blade horizontal axis wind turbine. The validation of the calculations is performed by comparing with experimental results. The power coefficients calculated without turbulence models are in agreement with the experimental data for a tip speed ratio greater than 5
Cosmic Galaxy-IGM HI Relation at Probed in the COSMOS/UltraVISTA deg Field
We present spatial correlations of galaxies and IGM HI in the
COSMOS/UltraVISTA 1.62 deg field. Our data consist of 13,415 photo-
galaxies at with and the Ly forest absorptions in
the background quasar spectra selected from SDSS data with no signature of
damped Ly system contamination. We estimate a galaxy overdensity
in an impact parameter of 2.5 pMpc, and calculate the Ly
forest fluctuations whose negative values
correspond to the strong Ly forest absorptions. We identify weak
evidence of an anti-correlation between and with a Spearman's rank correlation coefficient of suggesting
that the galaxy overdensities and the Ly forest absorptions positively
correlate in space at the confidence level. This positive
correlation indicates that high- galaxies exist around an excess of HI gas
in the Ly forest. We find four cosmic volumes, dubbed
-, that have extremely large (small) values of () and (), three
out of which, -, significantly depart from the correlation,
and weaken the correlation signal. We perform cosmological hydrodynamical
simulations, and compare with our observational results. Our simulations
reproduce the correlation, agreeing with the observational results. Moreover,
our simulations have model counterparts of -, and suggest
that the observations pinpoint, by chance, a galaxy overdensity like a
proto-cluster, gas filaments lying on the sightline, a large void, and
orthogonal low-density filaments. Our simulations indicate that the significant
departures of - are produced by the filamentary large-scale
structures and the observation sightline effects.Comment: 14 pages, 12 figures. Accepted for publication in Ap
Small Angle X-Ray Scattering Imaging of Soft Tissue by Using Laue Diffraction Optical System
We performed a feasibility study of Small angle X-ray scattering imaging under the condition of X-ray bright field imaging by Laue crystal diffraction optics of X-ray dark-field imaging that works as an angular analysis. Collagen in chicken tibia containing abundant soft fibrous tissue was chosen as a specimen. In traditional Small angle X-ray scattering optical system, we can derive the structure information of sample by calculating q value which is available from a scattering pattern. Thus it is usually necessary to conduct a 2D scan in order to obtain scattering image. In this paper it is described by a method by which not only small angle X-ray scattering imaging is available directly but also bright-field imaging and dark-field imaging can be obtained at the same time. As the first step, the feasibility of the imaging method should be confirmed by taking pictures of the samples with known periodic length. The preliminary test showed that the collgan’s lattice spacing d is 65.1 nm that was also taken photos by scanning electron microscopy. By rotating Laue angular analyzer by 112 arcseconds small angle X-ray scattering image appeared in bright-field
Persistent Amplification of DNA Damage Signal Involved in Replicative Senescence of Normal Human Diploid Fibroblasts
Foci of phosphorylated histone H2AX and ATM are the surrogate markers of DNA double strand breaks. We previously reported that the residual foci increased their size after irradiation, which amplifies DNA damage signals. Here, we addressed whether amplification of DNA damage signal is involved in replicative senescence of normal human diploid fibroblasts. Large phosphorylated H2AX foci (>1.5 μm diameter) were specifically detected in presenescent cells. The frequency of cells with large foci was well correlated with that of cells positive for senescence-associated β-galactosidase staining. Hypoxic cell culture condition extended replicative life span of normal human fibroblast, and we found that the formation of large foci delayed in those cells. Our immuno-FISH analysis revealed that large foci partially localized at telomeres in senescent cells. Importantly, large foci of phosphorylated H2AX were always colocalized with phosphorylated ATM foci. Furthermore, Ser15-phosphorylated p53 showed colocalization with the large foci. Since the treatment of senescent cells with phosphoinositide 3-kinase inhibitor, wortmannin, suppressed p53 phosphorylation, it is suggested that amplification of DNA damage signaling sustains persistent activation of ATM-p53 pathway, which is essential for replicative senescence
Effects of safflower seed extract on arterial stiffness
Safflower seed extract (SSE) contains characteristic polyphenols and serotonin derivatives (N-( p-coumaroyl) serotonin and N-feruloylserotonin), which are reported to inhibit oxidation of low-density lipoprotein (LDL), formation of atherosclerotic plaques, and improve arterial stiffness as assessed by pulse wave analysis in animal models. The effects of long-term supplementation with SSE on arterial stiffness in human subjects were evaluated. This doubleblind, placebo-controlled study was conducted in 77 males (35–65 years) and 15 postmenopausal females (55–65 years) with high-normal blood pressure or mild hypertension who were not undergoing treatment. Subjects received SSE (70 mg/day as serotonin derivatives) or placebo for 12 weeks, and pulse wave measurements, ie, second derivative of photoplethysmogram (SDPTG), augmentation index, and brachial-ankle pulse wave velocity (baPWV) were conducted at baseline, and at weeks 4, 8, and 12. Vascular age estimated by SDPTG aging index improved in the SSE-supplemented group when compared with the placebo group at four (P = 0.0368) and 12 weeks (P = 0.0927). The trend of augmentation index reduction (P = 0.072 versus baseline) was observed in the SSE-supplemented group, but reduction of baPWV by SSE supplementation was not observed. The SSE-supplemented group also showed a trend towards a lower malondialdehyde-modified-LDL autoantibody titer at 12 weeks from baseline. These results suggest long-term ingestion of SSE in humans could help to improve arterial stiffness
Measuring effective orifice area of bileaflet mechanical valves in patients after aortic valve replacement using phase-contrast cine MR imaging
POSTER PRESENTATION2011 SCMR/Euro CMR Joint Scientific Sessions / Nice, France / 3-6 February 201
- …