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Search Results: 1 - 10 of 252512 matches for " V. K. Turchaninov "
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Novel Technology for Chlorination of Niobium and Tantalum Oxides and Their Low-Grade Ore Concentrates  [PDF]
B. A. Shainyan, Yu. S. Danilevich, Yu. L. Garmazov, A. L. Finkelstein, T. S. Aisueva, V. K. Turchaninov
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2008, DOI: 10.4236/jmmce.2008.72013
Abstract: A novel energy-economic and environmentally benign technological procedure for chlorination of niobium and tantalum oxides as well as their low-grade ore concentrates was elaborated. The process is based on using carbon tetrachloride or silicon tetrachloride as a chlorinating agent under pressure. It proceeds at moderate temperatures and is free from the shortcomings of conventional carbochlorination processes such as the use of chlorine gas at very high temperatures and formation of toxic products and ozone depleting agents (phosgene, carbon monoxide, chlorohydrocarbons).
Properties of observed Ly-$α$ forest
M. Demianski,A. Doroshkevich,V. Turchaninov
Physics , 2000, DOI: 10.1046/j.1365-8711.2000.03862.x
Abstract: The main observed properties of Ly-$\alpha$ absorbers are investigated on the basis of theoretical model of formation and evolution of DM structure elements. This model is generally consistent with simulations of absorbers formation and with statistical description of structure evolution based on the Zel'dovich theory. The analysis of redshift variations of comoving linear number density of absorbers was performed in our previous paper. We show that the observed characteristics of Doppler parameter can be related to the size of DM structure elements what allows us to explain the observed distribution of Doppler parameter. This distribution is found to be consistent with the Gaussian initial perturbations. The observed characteristics of entropy and column density, $N_{HI}$, confirm that merging of pancakes is the main evolutionary process at redshifts $z\geq 2$. The observed sample of absorbers characterizes mainly the matter distribution within large low density regions and therefore it is difficult to reconstruct the density field from the distribution of absorbers.
Redshift distribution of {\bf Ly-$α$} lines and metal systems
M. Demianski,A. G. Doroshkevich,V. Turchaninov
Physics , 2000, DOI: 10.1046/j.1365-8711.2000.03861.x
Abstract: The observed redshift distribution of Ly-$\alpha$ lines and metal systems is examined in order to discriminate and to trace the evolution of structure elements observed in the galaxy distribution, at small redshifts, and to test the theoretical description of structure evolution. We show that the expected evolution of filamentary component of structure describes quite well the redshift distribution of metal systems and stronger Ly-$\alpha$ lines with $\log(N_{HI})\geq$14, at $z\leq$ 3. The redshift distribution of weaker Ly-$\alpha$ lines can be attributed to the population of poorer structure elements (Zel'dovich pancakes), which were formed at high redshifts from the invisible DM and non luminous baryonic matter, and at lower redshifts they mainly merged and dispersed.
Statistical characteristics of observed Ly-$α$ forest and the shape of initial power spectrum
M. Demiański,A. Doroshkevich,V. Turchaninov
Physics , 2002, DOI: 10.1046/j.1365-8711.2003.06328.x
Abstract: Properties of $\sim$ 5000 observed Ly-$\alpha$ absorbers are investigated using the model of formation and evolution of DM structure elements based on the Zel'dovich theory. This model is generally consistent with simulations of absorbers formation, accurately describes the Large Scale Structure observed in the galaxy distribution at small redshifts and emphasizes the generic similarity of the LSS and absorbers. The simple physical model of absorbers asserts that they are composed of DM and gaseous matter and it allows us to estimate the column density and overdensity of DM and gaseous components and the entropy of the gas trapped within the DM potential wells. The parameters of DM component are found to be consistent with theoretical expectations for the Gaussian initial perturbations with the WDM--like power spectrum. We demonstrate the influence of the main physical factors responsible for the absorbers evolution. The analysis of redshift distribution of absorbers confirms the self consistence of the assumed physical model and allows to estimate the shape of the initial power spectrum at small scales what in turn restricts the mass of dominant fraction of DM particles to $M_{DM}\approx 0.6 - 2$ keV. Our results verify the redshift variations of intensity of the UV background by about $4 - 6$ times and indicate that, perhaps, the available observations underestimate the intensity of this background.
The evolution of groups and clusters
S. Gottloeber,A. Klypin,A. V. Kravtsov,V. Turchaninov
Physics , 1999,
Abstract: Using high resolution N-body simulations we have studied the formation and evolution of clusters and groups in a LCDM cosmological model. Groups of galaxies have been formed already before z=4. The total number of small bound systems and the total number of galaxies in these small systems rapidly decreases after z=1.5. The fraction of isolated galaxies remains approximately constant after z =1, whereas the fraction of galaxies in groups decreases. Merging of groups and accretion leads to cluster formation at z < 2. Some of the groups merge into large isolated halos.
Statistical characteristics of simulated walls
M. Demianski,A. G. Doroshkevich,V. Mueller,V. Turchaninov
Physics , 2000, DOI: 10.1046/j.1365-8711.2000.03693.x
Abstract: The large scale matter distribution in three different simulations of CDM models is investigated and compared with corresponding results of the Zel'dovich theory of nonlinear gravitational instability. We show that the basic characteristics of wall-like structure elements are well described by this theory, and that they can be expressed by the cosmological parameters and a few spectral moments of the perturbation spectrum. Therefore the characteristics of such elements provide reasonable estimates of these parameters. We show that the compressed matter is relaxed and gravitationally confined, what manifests itself in the existence of walls as (quasi)stationary structure elements with life time restricted by their disruption into high density clouds. The matter distribution is investigated both in the real and redshift spaces. In both cases almost the same particles form the walls, and we estimate differences in corresponding wall characteristics. The same methods are applied to several mock catalogues of 'galaxies' what allows us to characterize a large scale bias between the spatial distribution of dark matter and of simulated `galaxies'.
Large Scale Structures in the Las Campanas Redshift Survey and in Simulations
V. Müller,A. G. Doroshkevich,J. Retzlaff,V. Turchaninov
Physics , 1998,
Abstract: The large supercluster structures obvious in recent galaxy redshift surveys are quantified using an one-dimensional cluster analysis (core sampling) and a three-dimensional cluster analysis based on the minimal spanning tree. The comparison with the LCRS reveals promising stable results. At a mean overdensity of about ten, the supercluster systems form huge wall-like structures comprising about 40% of all galaxies. The overdense clusters have a low mean transverse velocity dispersion of about 400 km/s, i.e. they look quite narrow in redshift space. We performed N-body simulations with large box sizes for six cosmological scenarios. The quantitative analysis shows that the observed structures can be understood best in low density models with $\Omega_m \le 0.5$ with or without a cosmological constant.
Superlarge-Scale Structure in N-body Simulations
A. G. Doroshkevich,V. Müller,J. Retzlaff,V. Turchaninov
Physics , 1999, DOI: 10.1046/j.1365-8711.1999.02531.x
Abstract: The simulated matter distribution on large scales is studied using core-sampling, cluster analysis, inertia tensor analysis, and minimal spanning tree techniques. Seven simulations in large boxes for five cosmological models with COBE normalized CDM-like power spectra are studied. The wall-like Super Large Scale Structure with parameters similar to the observed one is found for the OCDM and LCDM models with Omega_m h = 0.3 & 0.245. In these simulations, the rich structure elements with a typical value for the largest extension of \~(30 - 50) h^-1 Mpc incorporate ~40% of matter with overdensity of about 10 above the mean. These rich elements are formed due to the anisotropic nonlinear compression of sheets with original size of ~(15 - 25) h^{-1} Mpc. They surround low-density regions with a typical diameter ~(50 - 70) h^{-1} Mpc. The statistical characteristics of these structures are found to be approximately consistent with observations and theoretical expectations. The cosmological models with higher matter density \Omega_m=1 in CDM with Harrison-Zeldovich or tilted power spectra cannot reproduce the characteristics of the observed galaxy distribution due to the very strong disruption of the rich structure elements. Another model with a broken scale invariant initial power spectrum (BCDM) shows not enough matter concentration in the rich structure elements.
Gauss--Legendre Sky Pixelization (GLESP) for CMB maps
A. G. Doroshkevich,P. D. Naselsky,O. V. Verkhodanov,D. I. Novikov,V. I. Turchaninov,I. D. Novikov,P. R. Christensen,L. -Y. Chiang
Physics , 2003, DOI: 10.1142/S0218271805006183
Abstract: A new scheme of sky pixelization is developed for CMB maps. The scheme is based on the Gauss--Legendre polynomials zeros and allows one to create strict orthogonal expansion of the map. A corresponding code has been implemented and comparison with other methods has been done.
First Release of Gauss-Legendre Sky Pixelization (GLESP) software package for CMB analysis
A. G. Doroshkevich,P. D. Naselsky,O. V. Verkhodanov,D. I. Novikov,V. I. Turchaninov,I. D. Novikov,P. R. Christensen,L. -Y. Chiang
Mathematics , 2005,
Abstract: We report the release of the Gauss--Legendre Sky Pixelization (GLESP) software package version 1.0. In this report we present the main features and functions for processing and manipulation of sky signals. Features for CMB polarization is underway and to be incorporated in a future release. Interested readers can visit http://www.glesp.nbi.dk (www.glesp.nbi.dk) and register for receiving the package.
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