Silica sol-gel materials with metal and semiconductor nanoparticles: synthesis, structure and optical features

Recent achievements on fabrication, structure and optical features of the metal- and semiconductor-doped silica sol-gel materials are reviewed. The nanoparticles of copper and copper compounds (oxides, sulfides and selenides) have been produced by means of the modified silica-based sol-gel technique within the two types of materials: amorphous silica films and monolithic glasses. The features of optical absorption are discussed in dependence on chemical composition. They are variable by stoichiometry of the compounds, size of particles, their concentration and localization in the matrix. These factors determine optical properties of mate- rials and open pathways of their application, in particular, as switching and beam-controlling elements in near-IR lasers. The quantum confinement and a partial surface chemical modification of the nanoparticles are considered as possible reasons for occurrence of the optical features specific for the copper multivalent compounds

A search for gamma-ray point sources with the Carpet shower array

A search for super-high energy gamma-ray point sources has been carried out. The well known source Cyg X-3 was observed first and preliminary results of data analysis are presented. There is not positive excess of showers from the source region, but phase analysis discovers a small pulse at phase 0.6 which corresponds to the integral flux (6 + or - 3) X 10 to the minus 14th power cm-2 sec-1 at E sub gamma 3x10 to the 14th power eV

Invariant Sets and Explicit Solutions to a Third-Order Model for the Shearless Stratified Turbulent Flow

We study dynamics of the shearless stratified turbulent flows. Using the method of differential constraints we find a class of explicit solutions to the problem under consideration and establish that the differential constraint obtained coincides with the well-known Zeman--Lumley model for stratified flows.Comment: arxiv version is already officia

New global stability estimates for monochromatic inverse acoustic scattering

We give new global stability estimates for monochromatic inverse acoustic scattering. These estimates essentially improve estimates of [P. Hahner, T. Hohage, SIAM J. Math. Anal., 33(3), 2001, 670-685] and can be considered as a solution of an open problem formulated in the aforementioned work

Analysis of Numerical Errors in the DSMC Method

Abstract. The direct simulation Monte Carlo (DSMC) method is one of the most popular numerical methods used to model rarefied gas environment flows. In order to predict the accuracy of a solution obtained by the DSMC method we have to be able to estimate its accuracy. In the work presented here we have developed a technique to estimate the numerical accuracy of the DSMC method. This paper presents a derivation of expressions of the variance of the DSMC estimators of number density and translational temperature, and the corresponding comparison with the empirical variance. A discussion of the deterministic numerical errors corresponding to typical DSMC parameters such as the time step, cell volume, and total number of simulated particles is given. Moreover, a comparison of two different DSMC schemes, No Time Counter (NTC) and Majorant Frequency (MF), is made

Large-Scale Sidereal Anisotropy of Galactic Cosmic-Ray Intensity Observed by the Tibet Air Shower Array

We present the large-scale sidereal anisotropy ofgalactic cosmic-ray intensity in the multi-TeV region observed with the Tibet-IIIair shower array during the period from 1999 through 2003. The sidereal daily variation of cosmic rays observed in this experiment shows an excess of relative intensity around $4\sim7$ hours local sidereal time, as well as a deficit around 12 hours local sidereal time. While the amplitude of the excess is not significant when averaged over all declinations, the excess in individual declinaton bands becomes larger and clearer as the viewing direction moves toward the south. The maximum phase of the excess intensity changes from $\sim$7 at the northern hemisphere to $\sim$4 hours at the equatorial region. We also show that both the amplitude and the phase of the first harmonic vector of the daily variation are remarkably independent of primary energy in the multi-TeV region. This is the first result determining the energy and declination dependences of the full 24-hour profiles of the sidereal daily variation in the multi-TeV region with a single air shower experiment.Comment: 13 pages, 3 figures, 1 table. Accepted for publication in ApJ

Observation by an Air-Shower Array in Tibet of the Multi-TeV Cosmic-Ray Anisotropy due to Terrestrial Orbital Motion Around the Sun

We report on the solar diurnal variation of the galactic cosmic-ray intensity observed by the Tibet III air shower array during the period from 1999 to 2003. In the higher-energy event samples (12 TeV and 6.2 TeV), the variations are fairly consistent with the Compton-Getting anisotropy due to the terrestrial orbital motion around the sun, while the variation in the lower-energy event sample (4.0 TeV) is inconsistent with this anisotropy. This suggests an additional anisotropy superposed at the multi-TeV energies, e.g. the solar modulation effect. This is the highest-precision measurement of the Compton-Getting anisotropy ever made.Comment: 4 pages, 2 figures, includes .bbl fil

High Altitude Plume Simulations for a Solid Propellant Rocket

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76644/1/AIAA-2007-1013-267.pd