979 research outputs found
Fingerprints of Spin-Orbital Physics in Crystalline O
The alkali hyperoxide KO is a molecular analog of strongly-correlated
systems, comprising of orbitally degenerate magnetic O ions. Using
first-principles electronic structure calculations, we set up an effective
spin-orbital model for the low-energy \textit{molecular} orbitals and argue
that many anomalous properties of KO replicate the status of its orbital
system in various temperature regimes.Comment: 4 pages, 2 figures, 1 tabl
Tidal dwarfs in the M81 group: the second generation?
We derive quantitative star formation histories of the four suspected tidal
dwarf galaxies in the M81 group, HolmbergIX, BK3N, Arp-loop (A0952+69), and
Garland, using Hubble Space Telescope/Wide Field Planetary Camera2 images in
F606W and F814W obtained as part of a Snapshot survey of dwarf galaxies in the
Local Universe. We consider the spatial distribution and ages of resolved
stellar populations in these dwarf irregular galaxies. We use synthetic
color-magnitude diagrams to derive the ages of the major star formation
episodes, star formation rates, and approximate metallicity ranges. All the
galaxies show evidence of continuous star formation between about 20 and 200
Myr ago with star formation rates in the range 7.5*10^(-3)- 7.6*10^(-4)
M(sun)/yr. The metallicity of the detected stars spans a wide range, and have
lower than solar abundance. A possible scenario is that all four dwarf galaxies
were formed from material in the metal-poor outer part of the giant spiral
galaxy M81 after the tidal interaction between M81, M82, and NGC3077 about 200
Myr ago. While we do not directly detect pronounced old stellar populations,
the photometric limits of our data are such that the presence of such a
population is not entirely ruled out
Method of the balanced development of automobile service network on the basis of complex indicators system
In article one of ways of improvement of automobile service quality by balanced development of firm service network is described. The analysis algorithm of network subjects work is done. As criterion of an estimation of network activity performance the estimation integrated indicator of all network and estimation complex indicators of its subjects are offered
Galaxy Flow in the Canes Venatici I Cloud
We present an analysis of Hubble Space Telescope/WFPC2 images of eighteen
galaxies in the Canes Venatici I cloud.
We derive their distances from the luminosity of the tip of the red giant
branch stars with a typical accuracy of ~12 %. The resulting distances are 3.9
Mpc (UGC 6541), 4.9 Mpc (NGC 3738), 3.0 Mpc (NGC 3741), 4.5 Mpc (KK 109), >6.3
Mpc (NGC 4150), 4.2 Mpc (UGC 7298), 4.5 Mpc (NGC 4244), 4.6 Mpc (NGC 4395), 4.9
Mpc (UGC 7559), 4.2 Mpc (NGC 4449), 4.4 Mpc (UGC 7605), 4.6 Mpc (IC 3687), 4.7
Mpc (KK 166), 4.7 Mpc (NGC 4736), 4.2 Mpc (UGC 8308), 4.3 Mpc (UGC 8320), 4.6
Mpc (NGC 5204), and 3.2 Mpc (UGC 8833). The CVn I cloud has a mean radial
velocity of 286 +- 9 km/s, a mean distance of 4.1 +- 0.2 Mpc, a radial velocity
dispersion of 50 km/s, a mean projected radius of 760 kpc, and a total blue
luminosity of 2.2 * 10^{10} L_{\sun}. Assuming virial or closed orbital motions
for the galaxies, we estimated their virial and their orbital
mass-to-luminosity ratio to be 176 and 88 M_{\sun}/L_{\sun}, respectively.
However, the CVn I cloud is characterized by a crossing time of 15 Gyr, and is
thus far from a state of dynamical equilibrium. The large crossing time for the
cloud, its low content of dSph galaxies ( %), and the almost
``primordial'' shape of its luminosity function show that the CVn I complex is
in a transient dynamical state, driven rather by the free Hubble expansion than
by galaxy interactions.Comment: 23 pages, 6 figures, A&A in preparation. The version does not include
Figure 2. High resolution figures 1 and 2 (11311k) are available at
http://luna.sao.ru/~sme/figsCVn.tar.g
System approach at risk management of the autoservice enterprise
In the article methods of control over risks of the service enterprises during creation of customer-oriented firm service system are analyzed. It is shown that system approach to risk management ensures the adoption of science-based solutions, minimizes consequences of risk situations. One of ways to calculate an integrated indicator of the risk of loss of the service enterprise competitiveness is described. Variants of the risk as-sessment to reduce the effectiveness of service enterprises by monitoring indicators based on the results of their monitoring are given
Automotive enterprises flow production improvement based on the management process intellectualization
© 2018 IEEE. The analysis of optimization methods of the flow organization of technological assembly processes, shows that the problem should be solved in a complex manner. The scheme of interaction of decision support system (DSS) modules for the automotive enterprise is presented. The simulation model of the process of installing a pre-starting liquid engine heater (PLEH) is developed. The adequacy assessment of the developed simulation model is carried out based on the average values of the model and system responses. The optimization of the simulation model based on the number of distributed workers in positions is made. The average installation time of one PLEH decreased by 12%, the maximum time - by 9.5%
Local galaxy flows within 5 Mpc
We present Hubble Space Telescope/WFPC2 images of sixteen dwarf galaxies as
part of our snapshot survey of nearby galaxy candidates. We derive their
distances from the luminosity of the tip of the red giant branch stars with a
typical accuracy of ~12%. The resulting distances are 4.26 Mpc (KKH 5), 4.74
Mpc (KK 16), 4.72 Mpc (KK 17), 4.66 Mpc (ESO 115-021), 4.43 Mpc (KKH 18), 3.98
Mpc (KK 27), 4.61 Mpc (KKH 34), 4.99 Mpc (KK 54), 4.23 Mpc (ESO 490-017), 4.90
Mpc (FG 202), 5.22 Mpc (UGC 3755), 5.18 Mpc (UGC 3974), 4.51 Mpc (KK 65), 5.49
Mpc (UGC 4115), 3.78 Mpc (NGC 2915), and 5.27 Mpc (NGC 6503). Based on
distances and radial velocities of 156 nearby galaxies, we plot the local
velocity-distance relation, which has a slope of H_0 = 73 km/(c * Mpc) and a
radial velocity dispersion of 85 km/s. When members of the M81 and CenA groups
are removed, and distance errors are taken into account, the radial velocity
dispersion drops to sigma_v=41 km/s. The local Hubble flow within 5 Mpc exibits
a significant anisotropy, with two infall peculiar velocity regions directed
towards the Supergalactic poles. However, two observed regions of outflow
peculiar velocity, situated on the Supergalactic equator, are far away (~50
degr.) from the Virgo/anti-Virgo direction, which disagrees with a spherically
symmetric Virgo-centric flow. About 63% of galaxies within 5 Mpc belong to
known compact and loose groups. Apart from them, we found six new probable
groups, consisting entirely of dwarf galaxies.Comment: 22 pages, 7 figures. A&A Accepted. High resolution Figures 1 and 2
(9616k) are available at http://www.sao.ru/~sme/figs.tar.g
Features of shear transformation texture in seamless pipes
Microstructure and texture in seamless 0.08C-Cr-Mo-V, 0.25C-Cr-Mo-V-Nb, 0.08-13Cr-3Ni-Mo-V-Nb, and 18Cr-9Ni steel pipes are studied in the as-rolled and heat-treated states using orientation EBSD microscopy. It has been found that all types of microstructure (ferrite, martensite, and bainite) in products, both after hot rolling and after heat treatment, have well-defined axial crystallographic texture, where the direction is predominately perpendicular to the pipe surface. It is demonstrated that texture formation in heat-treated states is inherited due to the following factors important for the rules of orientation selection during the γ→α phase transformation: 1) occurrence of stable orientation of austenite grains resulted from straining; 2) special misorientation (boundaries) of austenite grains where transformation starts; 3) orientation relationships known for phase transformation; 4) thermal stresses in a product, formed during cooling. The latter can be considered as factor determining special texture in seamless steel pipes. © 2018 Author(s)
First-Principles Study of Substitutional Metal Impurities in Graphene: Structural, Electronic and Magnetic Properties
We present a theoretical study using density functional calculations of the
structural, electronic and magnetic properties of 3d transition metal, noble
metal and Zn atoms interacting with carbon monovacancies in graphene. We pay
special attention to the electronic and magnetic properties of these
substitutional impurities and found that they can be fully understood using a
simple model based on the hybridization between the states of the metal atom,
particularly the d shell, and the defect levels associated with an
unreconstructed D3h carbon vacancy. We identify three different regimes
associated with the occupation of different carbon-metal hybridized electronic
levels:
(i) bonding states are completely filled for Sc and Ti, and these impurities
are non-magnetic;
(ii) the non-bonding d shell is partially occupied for V, Cr and Mn and,
correspondingly, these impurties present large and localized spin moments;
(iii) antibonding states with increasing carbon character are progressively
filled for Co, Ni, the noble metals and Zn. The spin moments of these
impurities oscillate between 0 and 1 Bohr magnetons and are increasingly
delocalized.
The substitutional Zn suffers a Jahn-Teller-like distortion from the C3v
symmetry and, as a consequence, has a zero spin moment. Fe occupies a distinct
position at the border between regimes (ii) and (iii) and shows a more complex
behavior: while is non-magnetic at the level of GGA calculations, its spin
moment can be switched on using GGA+U calculations with moderate values of the
U parameter.Comment: 13 figures, 4 tables. Submitted to Phys. Rev. B on September 26th,
200
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