192 research outputs found
On insertion-deletion systems over relational words
We introduce a new notion of a relational word as a finite totally ordered
set of positions endowed with three binary relations that describe which
positions are labeled by equal data, by unequal data and those having an
undefined relation between their labels. We define the operations of insertion
and deletion on relational words generalizing corresponding operations on
strings. We prove that the transitive and reflexive closure of these operations
has a decidable membership problem for the case of short insertion-deletion
rules (of size two/three and three/two). At the same time, we show that in the
general case such systems can produce a coding of any recursively enumerable
language leading to undecidabilty of reachability questions.Comment: 24 pages, 8 figure
Thermalization of coupled atom-light states in the presence of optical collisions
The interaction of a two-level atomic ensemble with a quantized single mode
electromagnetic field in the presence of optical collisions (OC) is
investigated both theoretically and experimentally. The main accent is made on
achieving thermal equilibrium for coupled atom-light states (in particular
dressed states). We propose a model of atomic dressed state thermalization that
accounts for the evolution of the pseudo-spin Bloch vector components and
characterize the essential role of the spontaneous emission rate in the
thermalization process. Our model shows that the time of thermalization of the
coupled atom-light states strictly depends on the ratio of the detuning and the
resonant Rabi frequency. The predicted time of thermalization is in the
nanosecond domain and about ten times shorter than the natural lifetime at full
optical power in our experiment. Experimentally we are investigating the
interaction of the optical field with rubidium atoms in an ultra-high pressure
buffer gas cell under the condition of large atom-field detuning comparable to
the thermal energy in frequency units. In particular, an observed detuning
dependence of the saturated lineshape is interpreted as evidence for thermal
equilibrium of coupled atom-light states. A significant modification of
sideband intensity weights is predicted and obtained in this case as well.Comment: 14 pages, 12 figures; the content was edite
High temperature phase transition in the coupled atom-light system in the presence of optical collisions
The problem of photonic phase transition for the system of a two-level atomic
ensemble interacting with a quantized single-mode electromagnetic field in the
presence of optical collisions (OC) is considered. We have shown that for large
and negative atom-field detuning a photonic field exhibits high temperature
second order phase transition to superradiant state under thermalization
condition for coupled atom-light states. Such a transition can be connected
with superfluid (coherent) properties of photon-like low branch (LB)
polaritons. We discuss the application of metallic cylindrical waveguide for
observing predicted effects.Comment: 8 pages, 2 figure
Slow and fast micro-field components in warm and dense hydrogen plasmas
The aim of this work is the investigation of the statistical properties of
local electric fields in an ion-electron two component plasmas for coupled
conditions. The stochastic fields at a charged or at a neutral point in plasmas
involve both slow and fast fluctuation characteristics. The statistical study
of these local fields based on a direct time average is done for the first
time. For warm and dense plasma conditions, typically , , well controlled molecular dynamics (MD)
simulations of neutral hydrogen, protons and electrons have been carried out.
Relying on these \textit{ab initio} MD calculations this work focuses on an
analysis of the concepts of statistically independent slow and fast local field
components, based on the consideration of a time averaged electric field. Large
differences are found between the results of these MD simulations and
corresponding standard results based on static screened fields. The effects
discussed are of importance for physical phenomena connected with stochastic
electric field fluctuations, e.g., for spectral line broadening in dense
plasmas.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let
Proceedings of the Scientific-Practical Conference "Research and Development - 2016"
This open access book relates to the III Annual Conference hosted by the Russian Federal Ministry of Education and Science in December 2016. This event has summarized, analyzed and discussed the interim results, academic outputs and scientific achievements of the Russian Federal Targeted Programme for Research and Development in priority areas of development of the Russian Scientific and Technological Complex for 2014-2020. It contains 75 selected papers from 6 areas considered priority by the Federal programme: computer science, ecology & environment sciences; energy and energy efficiency; life sciences; nanoscience & nanotechnology; and transport & communications. The chapters report the results of the 3-years research projects supported by the Programme and finalized in 2016
Hydrogen atom in crossed external fields reexemined by the moment method
Recurrence relations of perturbation theory for hydrogen ground state are
obtained. With their aid polarizabilities in constant perpendicular electric
and magnetic fields are computed up to 80th order. The high orders asymptotic
is compared with its quasiclassical estimate. For the case of arbitrary mutual
orientation of external fields a general sixth order formula is given.Comment: 11 pages, LaTeX, 2 figures (eps
High orders of the perturbation theory for hydrogen atom in magnetic field
The states of hydrogen atom with principal quantum number and zero
magnetic quantum number in constant homogeneous magnetic field are
considered. The coefficients of energy eigenvalues expansion up to 75th order
in powers of are obtained for these states. The series for energy
eigenvalues and wave functions are summed up to values of the order
of atomic magnetic field. The calculations are based on generalization of the
moment method, which may be used in other cases of the hydrogen atom
perturbation by a polynomial in coordinates potential.Comment: 16 pages, LaTeX, 6 figures (ps, eps
Kinetics of thermal destruction of highly porous anionexchange resin TOKEM-320Y
Temperature characteristics, stages and thermal effects of the processes occurring during the thermolysis of TOKEM-320Y anion-exchange resin in an atmosphere of air were determined by differential thermal analysis. The activation energies and the orders of reactions of thermal decomposition of the resin were calculated by the Kissinger and Metzger-Horowitz methods using the TG curves obtained at different heating rates of the resin. Models are proposed that most accurately describe the decomposition of TOKEM-320Y in air in the temperature range 25-800 °C
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