437 research outputs found
THECOMPARISON OF TWO DIFFERENT SPORTING EVENTS BASEDONTHETYPICALBEHAVIOROFTHEACTIVE SPECTATORS AND GRANDSTAND VIBRATIONS INDUCED BY THEM
The paper describes especially the typical behavior of two active spectators crowds involved in two substantially different sporting events, namely, ice hockey games and a biathlon world cup competition. In both cases, spectators behavior was observed together with grandstand structure dynamic response to their cheering activities. The experimental results obtained during both events were mutually compared and discussed whether the dynamic loading and its effects on the grandstand structures are similar for the two compared spectators crowds
WHICH FANS ARE THE BIGGEST ACCELERATION OF THE GRANDSTAND?
The fans of AC Sparta Prague and SK Slavie Prague have been arguing about the fact whose fans support their team better since the end of 20th century. There have been made many experiments on the intensity of vibrations at football stadiums during matches. Altogether 11 matches were watched. Frequencies caused by the fans leadinng to vibrations and the size of those vibrations were provided from the results. Based on those facts the question about the bigger intensity of fans' support was answered
Continuum Pumping of [Fe II] in the Orion Nebula
This paper presents detailed comparisons between numerical simulations of Fe II emission spectra and recent high-resolution and signal-to-noise spectra of the Orion Nebula. We have identified 40 [Fe II] lines in the spectrum, allowing extensive comparisons between theory and observations. The identifications are based on predictions of a realistic model of the Fe II atom, which includes the lowest 371 levels (all levels up to 11.6 eV). We investigate the dependence of the spectrum on electron density and on pumping by the stellar continuum. Orion is important because it provides a relatively simple environment in which to test complex simulations. We have identified the pumping routes that are responsible for the observed emission. Our theoretical model of Fe II emission is in good agreement with the observational data
Explorations on anisotropic regularisation of dynamic inverse problems by bilevel optimisation
We explore anisotropic regularisation methods in the spirit of [Holler & Kunisch, 14]. Based on ground truth data, we propose a bilevel optimisation strategy to compute the optimal regularisation parameters of such a model for the application of video denoising. The optimisation poses a challenge in itself, as the dependency on one of the regularisation parameters is non-linear such that the standard existence and convergence theory does not apply. Moreover, we analyse numerical results of the proposed parameter learning strategy based on three exemplary video sequences and discuss the impact of these results on the actual modelling of dynamic inverse problems
Scattering by Interstellar Dust Grains. II. X-Rays
Scattering and absorption of X-rays by interstellar dust is calculated for a
model consisting of carbonaceous grains and amorphous silicate grains. The
calculations employ realistic dielectric functions with structure near X-ray
absorption edges, with resulting features in absorption, scattering, and
extinction.
Differential scattering cross sections are calculated for energies between
0.3 and 10 keV. The median scattering angle is given as a function of energy,
and simple but accurate approximations are found for the X-ray scattering
properties of the dust mixture, as well as for the angular distribution of the
scattered X-ray halo for dust with simple spatial distributions. Observational
estimates of the X-ray scattering optical depth are compared to model
predictions. Observations of X-ray halos to test interstellar dust grain models
are best carried out using extragalactic point sources.Comment: ApJ, accepted. 27 pages, 12 figures. Much of this material was
previously presented in astro-ph/0304060v1,v2,v3 but has been separated into
the present article following recommendation by the refere
TRMM-related research: Tropical rainfall and energy analysis experiment
The overall science objective of the participation in TRMM is the determination of daily rainfall and latent heating in the tropical atmosphere using TRMM and complementary spacecraft observations. The major focus these first three years has been to extend, in space and time, the TRMM satellite observations of rainfall. Observations from TRMM active and passive microwave radiometers will provide the fundamental observations for understanding the hydrological cycle of the tropics. Due to the orbit of the TRMM satellite and the extreme variability of convective rain systems, the TRMM observations provide rainfall estimates representative of a one month period. Monthly mean rainfall rates provide valuable information; however, this time scale limitation neglects the great value of the data towards a better understanding of the physics of tropical convection. Many tropical periodicities will not be characterized by these monthly averages, e.g. diurnal cycles, the 4-6 day easterly waves, and the 30 to 60 day cycle. In the spatial domain, due to its orbit, the TRMM satellite will over-fly many convective systems only once. Indeed, some precipitating systems will not be sampled at all. Observations from geostationary satellites can be used to extend the TRMM observations to smaller time and space scales. Although geostationary satellites cannot probe the interiors of precipitating systems, they do observe their life cycles. To acquire information on cloud water content and rain rate, it is proposed to combine geostationary and other satellite observations with the TRMM satellite measurements
Prediction for the He I 10830A Absorption Wing in the Coming Event of Eta Carinae
We propose an explanation to the puzzling appearance of a wide blue
absorption wing in the He I 10830A P-Cygni profile of the massive binary star
Eta Carinae several months before periastron passage. Our basic assumption is
that the colliding winds region is responsible for the blue wing absorption. By
fitting observations, we find that the maximum outflow velocity of this
absorbing material is ~2300 km/s. We also assume that the secondary star is
toward the observer at periastron passage. With a toy-model we achieve two
significant results. (1) We show that the semimajor axis orientation we use can
account for the appearance and evolution of the wide blue wing under our basic
assumption. (2) We predict that the Doppler shift (the edge of the absorption
profile) will reach a maximum 0-3 weeks before periastron passage, and not
necessarily exactly at periastron passage or after periastron passage.Comment: 15 pages, 6 figures. Accepted for publication in MNRA
Chandra Phase-Resolved Spectroscopy of the Crab Pulsar
We present the first phase-resolved study of the X-ray spectral properties of
the Crab Pulsar that covers all pulse phases. The superb angular resolution of
the Chandra X-ray Observatory enables distinguishing the pulsar from the
surrounding nebulosity, even at pulse minimum. Analysis of the pulse-averaged
spectrum measures interstellar X-ray extinction due primarily to photoelectric
absorption and secondarily to scattering by dust grains in the direction of the
Crab Nebula. We confirm previous findings that the line-of-sight to the Crab is
underabundant in oxygen, although more-so than recently measured. Using the
abundances and cross sections from Wilms, Allen & McCray (2000) we find [O/H] =
(3.33 +/-0.25) x 10**-4. Analysis of the spectrum as a function of pulse phase
measures the low-energy X-ray spectral index even at pulse minimum -- albeit
with large statistical uncertainty -- and we find marginal evidence for
variations of the spectral index. The data are also used to set a new (3-sigma)
upper limit to the temperature of the neutron star of log T(infinity) < 6.30.Comment: 20 Pages including 7 figures. Accepted for publication in the
Astrophysical Journa
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