47 research outputs found
The evolution of peasant economy in the industrial center of Russia at the end of the XIXth - beginning of the XXth century: (according to the Zemstvo statistical data)
Die Kontroverse um den russischen Agrarkapitalismus ist ein Jahrhundert alt. Der vorliegende Beitrag analysiert die Faktoren, die die Evolution der Landwirtschaft im industriellen Zentrum Rußlands um die Jahrhundertwende determinieren. Eingegangen wird dabei auf die Arbeitsmarktstrukturen, unternehmerische Aktivitäten hinsichtlich industrieller Produktion und die Verteilung und Nutzung landwirtschaftlicher Flächen. Die Daten von 27 Verwaltungsbezirken (uyezds) werden mittels einer Komponentenanalyse, einem Regressionsmodell und der Methode additiver fuzzy-sets analysiert. (pmb)'The dispute on Russian agrarian capitalism is a century old. The author's aim is to reveal and to analyse the factors which determined the evolution of peasant economy in the Industrial Center on the turn of the century. The conditions for the development of the hiring of labourers, industrial activity and peasant land in use were also brought to light. The research was carrried out on the uyezds results of Zemstvo statistics. The methods used are: principal components analysis, regression models on the principal components and one of the new methods - the method of additive fuzzy types.' (author's abstract
Elliptic Flow and Dissipation in Heavy-Ion Collisions at E_{lab} = (1--160)A GeV
Elliptic flow in heavy-ion collisions at incident energies
(1--160)A GeV is analyzed within the model of 3-fluid dynamics (3FD). We show
that a simple correction factor, taking into account dissipative affects,
allows us to adjust the 3FD results to experimental data. This single-parameter
fit results in a good reproduction of the elliptic flow as a function of the
incident energy, centrality of the collision and rapidity. The experimental
scaling of pion eccentricity-scaled elliptic flow versus
charged-hadron-multiplicity density per unit transverse area turns out to be
also reasonably described. Proceeding from values of the Knudsen number,
deduced from this fit, we estimate the upper limit the shear
viscosity-to-entropy ratio as at the SPS incident energies.
This value is of the order of minimal observed in water and liquid
nitrogen.Comment: 10 pages, 7 figures, version accepted by Phys. Rev.
Local video-positioning system for industrial GPR
This article presents a local positioning system working with the industrial GPR OKO-2 (LOGIS) in the process of radio measurements. Here we discuss principles of the positioning system and the method of transferring location data into the GPR system as satellite data. The location uses a video recording of special tapes, which limit the scanning area. Tapes contain the special periodic pattern. A pair of video cameras are placed directly on the GPR body, cameras will register images of the limiting tapes. Results of experimental approbation of the GPR complex confirm the applicability of the system
Nonequilibrium effects in hadronic fireball expansion
We consider a spherical volume of hot and dense hadronic matter (fireball)
expanding into a vacuum. It is assumed that initially the fireball matter is in
local thermal and chemical equilibrium with vanishing collective velocity. The
time evolution of the fireball is studied in parallel within the GiBUU
transport model and an ideal hydrodynamic model. The equation of state of an
ideal hadronic gas is used in the hydrodynamic calculation. The same set of
hadronic species is used in transport and fluid-dynamical simulations. Initial
coordinates and momenta of hadrons in transport simulations have been randomly
generated by using the Fermi and Bose distributions for (anti)baryons and
mesons. The model results for radial profiles of densities and collective
velocities of different hadronic species are compared at different times. We
find that two considered models predict essential differences in time evolution
of hadron abundances, which are especially pronounced for hyperonic species.
This gives an evidence of a strong deviation from chemical equilibrium in
expanding hadronic matter.Comment: 23 pages, 12 figure
Collective mechanism of dilepton production in high-energy nuclear collisions
Collective bremsstrahlung of vector meson fields in relativistic nuclear
collisions is studied within the time-dependent Walecka model. Mutual
deceleration of the colliding nuclei is described by introducing the effective
stopping time and average rapidity loss of baryons. It is shown that
electromagnetic decays of virtual omega-mesons produced by bremsstrahlung
mechanism can provide a substantial contribution to the soft dilepton yield at
the SPS bombarding energies. In particular, it may be responsible for the
dilepton enhancement observed in 160 AGev central Pb+Au collisions. Suggestions
for future experiments to estimate the relative contribution of the collective
mechanism are given.Comment: 6 page
Dilepton production by bremsstrahlung of meson fields in nuclear collisions
We study the bremsstrahlung of virtual omega mesons due to the collective
deceleration of nuclei at the initial stage of an ultrarelativistic heavy-ion
collision. It is shown that electromagnetic decays of these mesons may give an
important contribution to the observed yields of dileptons. Mass spectra of
positron-electron and muon pairs produced in central Au+Au collisions are
calculated under some simplifying assumptions on the space-time variation of
the baryonic current in a nuclear collision process. Comparison with the CERES
data for 160 AGev Pb+Au collisions shows that the proposed mechanism gives a
noticeable fraction of the observed lepton pairs in the intermediate region of
invariant masses. Sensitivity of the dilepton yield to the in-medium
modification of masses and widths of vector mesons is demonstrated.Comment: 14 page
Evolution of Baryon-Free Matter Produced in Relativistic Heavy-Ion Collisions
A 3-fluid hydrodynamic model is introduced for simulating heavy-ion
collisions at incident energies between few and about 200 AGeV. In addition to
the two baryon-rich fluids of 2-fluid models, the new model incorporates a
third, baryon-free (i.e. with zero net baryonic charge) fluid which is created
in the mid-rapidity region. Its evolution is delayed due to a formation time
, during which the baryon-free fluid neither thermalizes nor interacts
with the baryon-rich fluids. After formation it thermalizes and starts to
interact with the baryon-rich fluids. It is found that for =0 the
interaction strongly affects the baryon-free fluid. However, at reasonable
finite formation time, =1 fm/c, the effect of this interaction turns out
to be substantially reduced although still noticeable. Baryonic observables are
only slightly affected by the interaction with the baryon-free fluid.Comment: 17 pages, 3 figures, submitted to the issue of Phys. of Atomic Nuclei
dedicated to S.T. Belyaev on the occasion of his 80th birthday, typos
correcte
Equation of state of hadron resonance gas and the phase diagram of strongly interacting matter
The equation of state of hadron resonance gas at finite temperature and
baryon density is calculated taking into account finite-size effects within the
excluded volume model. Contributions of known hadrons with masses up to 2 GeV
are included in the zero-width approximation. Special attention is paid to the
role of strange hadrons in the system with zero total strangeness. A density-
dependent mean field is added to guarantee that the nuclear matter has a
saturation point and a liquid-gas phase transition. The deconfined phase is
described by the bag model with lowest order perturbative corrections. The
phase transition boundary is found by using the Gibbs conditions with the
strangeness neutrality constraint. The sensitivity of the phase diagram to the
hadronic excluded volume and to the parametrization of the mean-field is
investigated. The possibility of strangeness-antistrangeness separation in the
mixed phase is analyzed. It is demonstrated that the peaks in the kaon to pion
and lambda to pion multiplicity ratios can be explained by a nonmonotonous
behavior of the strangeness fugacity along the chemical freeze-out line.Comment: 40 pages, 31 figure
Temperature dependent sound velocity in hydrodynamic equations for relativistic heavy-ion collisions
We analyze the effects of different forms of the sound-velocity function
cs(T) on the hydrodynamic evolution of matter formed in the central region of
relativistic heavy-ion collisions. At high temperatures (above the critical
temperature Tc) the sound velocity is calculated from the recent lattice
simulations of QCD, while in the low temperature region it is obtained from the
hadron gas model. In the intermediate region we use different interpolations
characterized by the values of the sound velocity at the local maximum (at T =
0.4 Tc) and local minimum (at T = Tc). In all considered cases the temperature
dependent sound velocity functions yield the entropy density, which is
consistent with the lattice QCD simulations at high temperature. Our
calculations show that the presence of a distinct minimum of the sound velocity
leads to a very long (about 20 fm/c) evolution time of the system, which is not
compatible with the recent estimates based on the HBT interferometry. Hence, we
conclude that the hydrodynamic description is favored in the case where the
cross-over phase transition renders the smooth sound velocity function with a
possible shallow minimum at Tc.Comment: 6 pages, 3 figures, talk given at SQM'07 Levoca, Slovaki