20,337 research outputs found
Sensing of meteorological variables by laser probe techniques Final report, 1 Aug. 1966 - 30 Jun. 1970
Optical laser sensing of atmospheric parameter
XMM-Newton observation of SN1993J in M81
In April 2001 SN1993J was observed with both the PN and MOS cameras of the
XMM-Newton observatory, resulting in about 7. x 10^4 s of acceptable
observation time. Fit results with both the PN and MOS2 camera spectra studying
different spectral models are presented. The spectra are best fitted in the
energy range between 0.3 and 11 keV by a 2-component thermal model with
temperatures of kT_1 = 0.34+-0.04 keV and kT_2 = 6.54+-4 keV, adopting
ionization equilibrium. A fit with a shock model also provides acceptable
results. Combining the XMM-Newton data with former X-ray observations of the
supernova, we discuss the general trend of L_x propto t^{-0.30} and the bump of
the X-ray light curve as well as former and recent spectral results in the
light of the standard SN model as first proposed by Chevalier in 1982.Comment: 7 pages, 3 figure
Statistical model of the powder flow regulation by nanomaterials
Fine powders often tend to agglomerate due to van der Waals forces between
the particles. These forces can be reduced significantly by covering the
particles with nanoscaled adsorbates, as shown by recent experiments. In the
present work a quantitative statistical analysis of the effect of powder flow
regulating nanomaterials on the adhesive forces in powders is given. Covering
two spherical powder particles randomly with nanoadsorbates we compute the
decrease of the mutual van der Waals force. The dependence of the force on the
relative surface coverage obeys a scaling form which is independent of the used
materials. The predictions by our simulations are compared to the experimental
results.Comment: 18 pages, 9 figures, 1 table, LaTeX; reviewed version with minor
changes, published (Powder Technology
On the recombination in high-order harmonic generation in molecules
We show that the dependence of high-order harmonic generation (HHG) on the
molecular orientation can be understood within a theoretical treatment that
does not involve the strong field of the laser. The results for H_2 show
excellent agreement with time-dependent strong field calculations for model
molecules, and this motivates a prediction for the orientation dependence of
HHG from the N_2 3s_g valence orbital. For both molecules, we find that the
polarization of recombination photons is influenced by the molecular
orientation. The variations are particularly pronounced for the N_2 valence
orbital, which can be explained by the presence of atomic p-orbitals.Comment: 6 pages 7 figure
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