30 research outputs found
Evolution of Near-Sun Solar Wind Turbulence
This paper presents a preliminary analysis of the turbulence spectrum of the
solar wind in the near-Sun region R < 50 Rs, obtained from interplanetary
scintillation measurements with the Ooty Radio Telescope at 327 MHz. The
results clearly show that the scintillation is dominated by density
irregularities of size about 100 - 500 km. The scintillation at the small-scale
side of the spectrum, although significantly less in magnitude, has a flatter
spectrum than the larger-scale dominant part. Furthermore, the spectral power
contained in the flatter portion rapidly increases closer to the Sun. These
results on the turbulence spectrum for R < 50 Rs quantify the evidence for
radial evolution of the small-scale fluctuations (</= 50 km) generated by
Alfven waves.Comment: 8 pages, 5 figures, To appear in "Magnetic Coupling between the
Interior and the Atmosphere of the Sun", eds. S.S. Hasan and R.J. Rutten,
Astrophysics and Space Science Proceedings, Springer-Verlag, Heidelberg,
Berlin, 200
Calculation of Navigation Corrections for a Single-Frequency GNSS Receiver Based on Satellite Radio Occultation Data
Highly active and stable bimetallic IR/Fe-USY catalysts for direct and NO-assisted N20 decomposition
The current research investigated N2O decompositions over the catalysts Ir/Fe-USY, Fe-USY and Ir-USY under various conditions, and found that a trace amount of iridium (0.1 wt%) incorporated into Fe-USY significantly enhanced N2O decomposition activity. The decomposition of N2O over this catalyst (Ir/Fe-USY-0.1%) was also partly assisted by NO present in the gas mixture, in contrast to the negative effect of NO over noble metal catalysts. Moreover, Ir/Fe-USY-0.1% can decompose more than 90% at 400 °C (i.e. the normal exhaust temperature) under simulated conditions of a typical nitric acid plant, e.g. 5000 ppm N2O, 5% O2, 700 ppm NO and 2% H2O in balance He, and such an activity can be kept for over 110 h under these strict conditions. The excellent properties of bimetallic Ir/Fe-USY-0.1% catalyst are presumably related to the good dispersion of Fe and Ir on the zeolite framework, the formation of framework Al–O–Fe species and the electronic synergy between the Ir and Fe sites. The reaction mechanism for N2O decomposition has been further discussed on the temperature-programmed desorption profiles of O2, N2 and NO2