11,358 research outputs found
Simulation of the Gravitational Collapse and Fragmentation of Rotating Molecular Clouds
In this paper we study the process of the subsequent (runaway) fragmentation
of the rotating isothermal Giant Molecular Cloud (GMC) complex. Our own
developed Smoothed Particle Hydrodynamics (SPH) gas-dynamical model
successfully reproduce the observed Cloud Mass-distribution Function (CMF) in
our Galaxy (even the differences between the inner and outer parts of our
Galaxy). The steady state CMF is established during the collapse within a
free-fall timescale of the GMC. We show that one of the key parameters, which
defines the observed slope of the present day CMF, is the initial ratio of the
rotational (turbulent) and gravitational energy inside the fragmented GMC.Comment: 8 pages, 9 EPS figures, special forma.cls class file is use
Periodic variations in the colours of the classical T Tauri star RW Aur A
The classical T Tauri star RW Aur A is an irregular variable with a large
amplitude in all photometric bands. In an extended series of photometric data
we found small-amplitude periodic variations in the blue colours of the star,
with a period of 2.64 days. The period was relatively stable over several
years. The amplitude of the periodic signal is 0.21 mag in U-V, 0.07 mag in
B-V, and about 0.02 mag in V-R and V-I. No periodicity was found in the V
magnitude. The relevance of this photometric period to the recently discovered
periodicity in spectral features of the star is discussed, and the hypothesis
of a hot spot is critically considered.Comment: 5 pages, 8 figures, uses new aa.cls, accepted for publication in
Astronomy and Astrophysic
Worldsheet Matter Superfields on Half-Shell
In this paper we discuss some of the effects of using "unidexterous"
worldsheet superfields, which satisfy worldsheet differential constraints and
so are partly on-shell, i.e., on half-shell. Most notably, this results in a
stratification of the field space that reminds of "brane-world" geometries.
Linear dependence on such superfields provides a worldsheet generalization of
the super-Zeeman effect. In turn, non-linear dependence yields additional
left-right asymmetric dynamical constraints on the propagating fields, again in
a stratified fashion.Comment: 15 pages, 2 figures; minor algebraic correction
Mathematical Models of Video-Sequences of Digital Half-Tone Images
This chapter is devoted to Mathematical Models (MM) of Digital Half-Tone Images (DHTI) and their
video-sequences presented as causal multi-dimensional Markov Processes (MP) on discrete meshes.
The difficulties of MM development for DHTI video-sequences of Markov type are shown. These difficulties are related to the enormous volume of computational operations required for their realization.
The method of MM-DHTI construction and their statistically correlated video-sequences on the basis
of the causal multi-dimensional multi-value MM is described in detail. Realization of such operations
is not computationally intensive; Markov models from the second to fourth order demonstrate this. The
proposed method is especially effective when DHTI is represented by low-bit (4-8 bits) binary numbers
Development of Nonlinear Filtering Algorithms of Digital Half-Tone Images
This chapter is devoted to solving the problem of algorithms and structures investigations for Radio
Receiver Devices (RRD) with the aim of the nonlinear filtering of Digital Half-Tone Images (DHTI)
representing the discrete-time and discrete-value random Markovian process with a number of states
greater than two. At that, it is assumed that each value of the DHTI element is represented by the binary
g-bit number, whose bits are transmitted via digital communication links in the presence of Additive
White Gaussian Noise (AWGN). The authors present the qualitative analysis of the optimal DHTI filtering
algorithm. The noise immunity of the optimal radio receiver device for the DHTI filtering with varying
quantization and dimension levels is investigated
How to measure the Pomeron phase in diffractive dipion photoproduction
The study of charge asymmetry of pions in the high-energy process gamma p ->
pi+ pi- p (e p -> e pi+ pi- p) at very small dipion momenta offers a method to
measure the phase of the forward hadronic (quasi)elastic amplitude gamma p ->
rho p. We estimate potential of such measurements at HERA.Comment: 12 pages, 2 figures; v4: more elaborate parametrizations of dipion
spectra implemented, discussion extende
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