24,435 research outputs found
Statistical characteristics of formation and evolution of structure in the universe
An approximate statistical description of the formation and evolution of
structure of the universe based on the Zel'dovich theory of gravitational
instability is proposed. It is found that the evolution of DM structure shows
features of self-similarity and the main structure characteristics can be
expressed through the parameters of initial power spectrum and cosmological
model. For the CDM-like power spectrum and suitable parameters of the
cosmological model the effective matter compression reaches the observed scales
20 -- 25Mpc with the typical mean separation of
wall-like elements 50 -- 70Mpc. This description can be
directly applied to the deep pencil beam galactic surveys and absorption
spectra of quasars. For larger 3D catalogs and simulations it can be applied to
results obtained with the core-sampling analysis.
It is shown that the interaction of large and small scale perturbations
modulates the creation rate of early Zel'dovich pancakes and generates bias on
the SLSS scale. For suitable parameters of the cosmological model and reheating
process this bias can essentially improve the characteristics of simulated
structure of the universe.
The models with give the best description of the
observed structure parameters. The influence of low mass "warm" dark matter
particles, such as a massive neutrino, will extend the acceptable range of
and .Comment: 20pages, 7 figures, MNRAS in pres
Statistical characteristics of MST radar echoes and its interpretation
Two concepts of fundamental importance are reviewed: the autocorrelation function and the frequency power spectrum. In addition, some turbulence concepts, the relationship between radar signals and atmospheric medium statistics, partial reflection, and the characteristics of noise and clutter interference are discussed
Study to define unsteady flow fields and their statistical characteristics
Preliminary estimates of space shuttle fluctuating pressure environments were made based on analyses of wind tunnel data, and empirical prediction techniques. Particular emphasis was given to the external tank and solid rocket boosters for the transonic speed regime during launch of a parallel-burn space shuttle configuration. Predicted environments are presented as space-averaged zonal profiles with progressive shading from zone to zone to illustrate spatial variations in the magnitude of the fluctuating pressure coefficient over the surfaces of the external tank and solid rocket boosters. Predictions are provided for the transonic Mach number range from 0.8 equal to or less than M sub infinity equal to or less than 1.5, and for supersonic Mach numbers of 2.0 and 3.0
Description and texts for the auxiliary programs for processing video information on the YeS computer. Part 3: Test program 2
The functions were discribed and the operating instructions, the block diagram and the proposed versions are given for modifying the program in order to obtain the statistical characteristics of multi-channel video information. The program implements certain man-machine methods for investigating video information. It permits representation of the material and its statistical characteristics in a form which is convenient for the user
Apparatus for statistical time-series analysis of electrical signals
An apparatus for performing statistical time-series analysis of complex electrical signal waveforms, permitting prompt and accurate determination of statistical characteristics of the signal is presented
Universal Probability Distribution Function for Bursty Transport in Plasma Turbulence
Bursty transport phenomena associated with convective motion present
universal statistical characteristics among different physical systems. In this
letter, a stochastic univariate model and the associated probability
distribution function for the description of bursty transport in plasma
turbulence is presented. The proposed stochastic process recovers the universal
distribution of density fluctuations observed in plasma edge of several
magnetic confinement devices and the remarkable scaling between their skewness
and kurtosis . Similar statistical characteristics of variabilities have
been also observed in other physical systems that are characterized by
convection such as the X-ray fluctuations emitted by the Cygnus X-1 accretion
disc plasmas and the sea surface temperature fluctuations.Comment: 10 pages, 5 figure
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