Low-temperature properties of monoalcohol glasses and crystals

We review and jointly discuss both earlier and recent experiments conducted by us on simple aliphatic glass-forming monoalcohols at low temperatures, including specific heat, thermal conductivity, Brillouin scattering and x-ray diffraction experiments. The family of simple monoalcohols constitutes an interesting model system to explore different relevant issues concerning molecular glass-forming liquids, low-temperature universal proper-ties of glasses, and even the glass transition phenomenon itself. More specifically, we discuss the role played by the molecular aspect ratio in vitrification/crystallization kinetics, the reported appearance of particular cases of polymorphism (in ethanol) and polyamorphism (in butanol), and especially the influence of position isomerism and the location of the hydrogen bond on the lattice dynamics and hence on the low-temperature universal prop-erties of glasses

Quantitative evaluation of the effects of positional versus orientational disorder on the scattering of acoustic phonons in disordered matter

The phonon scattering processes in the three solid phases of ethanol are investigated using thermal conductivity, light, and neutron-scattering measurements as well as molecular dynamics simulations on single- crystalline models for two crystalline modifications (fully ordered monoclinic and orientationally disordered bcc phases). The orientationally disordered crystal is found to exhibit a temperature dependence of the thermal conductivity that is remarkably close to that of a structurally disordered solid, especially at low temperatures. This results, together with measurements of Brillouin linewidths as derived from light scattering measurements, emphasize the role of orientational disorder in phonon scattering. The experimental results obtained on polycrystal samples are then discussed with the aid of computer simulations on single-crystalline models of both bcc and monoclinic crystals. Our findings are in good agreement with the wealth of thermodynamic and dynamic data available so far, but at variance with the inferences drawn from inelastic x-ray data on polycrystalline samples, where a common nature for the excitations in all phases is postulated

Lifetime distributions in the methods of non-equilibrium statistical operator and superstatistics

A family of non-equilibrium statistical operators is introduced which differ by the system age distribution over which the quasi-equilibrium (relevant) distribution is averaged. To describe the nonequilibrium states of a system we introduce a new thermodynamic parameter - the lifetime of a system. Superstatistics, introduced in works of Beck and Cohen [Physica A \textbf{322}, (2003), 267] as fluctuating quantities of intensive thermodynamical parameters, are obtained from the statistical distribution of lifetime (random time to the system degeneracy) considered as a thermodynamical parameter. It is suggested to set the mixing distribution of the fluctuating parameter in the superstatistics theory in the form of the piecewise continuous functions. The distribution of lifetime in such systems has different form on the different stages of evolution of the system. The account of the past stages of the evolution of a system can have a substantial impact on the non-equilibrium behaviour of the system in a present time moment.Comment: 18 page

Thermal Conductivity of Methane-Hydrate

The thermal conductivity of the methane hydrate CH4 (5.75 H2O) was measured in the interval 2-140 K using the steady-state technique. The thermal conductivity corresponding to a homogeneous substance was calculated from the measured effective thermal conductivity obtained in the experiment. The temperature dependence of the thermal conductivity is typical for the thermal conductivity of amorphous solids. It is shown that after separation of the hydrate into ice and methane, at 240 K, the thermal conductivity of the ice exhibits a dependence typical of heavily deformed fine-grain polycrystal. The reason for the glass-like behavior in the thermal conductivity of clathrate compounds has been discussed. The experimental results can be interpreted within the phenomenological soft-potential model with two fitting parameters.Comment: 13 pages, 3 figure

Development of risk assessment procedure task environment

В данной статье рассматриваются вопросы связанные с разработкой процедуры оценки опасности складывающейся оперативно-тактической обстановки. Проводится анализ и выбор аппарата формализации, формируется множество признаков для оценки разрабатывается процедура проведения экспертного опроса.У даній статті розглядаються питання пов'язані з розробкою процедури оцінки небезпеки оперативно-тактичної обстановки що складається. Проводиться аналіз і вибір апарату формалізації, формується безліч ознак для оцінки розробляється процедура проведення експертного опитування.This article discusses issues related to the development of the risk assessment procedure evolving operational and tactical situation. The analysis and selection of staff formalization, formed many signs designed to assess the procedure of expert survey