Thermal equilibration between two quantum systems

Two identical finite quantum systems prepared initially at different temperatures, isolated from the environment, and subsequently brought into contact are demonstrated to relax towards Gibbs-like quasi-equilibrium states with a common temperature and small fluctuations around the time-averaged expectation values of generic observables. The temporal thermalization process proceeds via a chain of intermediate Gibbs-like states. We specify the conditions under which this scenario occurs and corroborate the quantum equilibration with two different models.Comment: 10 pages, 9 figures, including supplementary materia

Mathematical model of composite fibre-glass aramide-wired cord rheological properties

This paper describes the rheological properties of composite fibre-glass aramide-wired cords which, in its turn, are applied in large-sized structures for space systems. Based on experimental data a new mathematical model describing creeping and relaxation of composite cords is proposed. This model defines the operation time of the composite cords to be 15 years

Calculation method for cable-beam shell structures

This paper presents a calculation method suitable for cable-beam shell structures. It is based on both nonlinear finite element and force density methods. The main idea is to define the solution sequence for stress - strain state problem of above mentioned structures by nonlinear finite element method. Every successive solution involves the previous one as an initial estimate in convergent domain. To find an initial estimate for the first solution a force density method is used. The proposed method is tested on a new large space umbrella reflector

Thermomechanical analysis of large deployable space reflector antenna

In this article results of large reflector thermal condition forecast using modern numerical simulation methods are presented. The results of thermal analysis are complemented with stress-strain analysis results of the whole structure under thermal loads

Quantum machine using cold atoms

For a machine to be useful in practice, it preferably has to meet two requirements: namely, (i) to be able to perform work under a load and (ii) its operational regime should ideally not depend on the time at which the machine is switched-on. We devise a minimal setup, consisting of two atoms only, for an ac-driven quantum motor which fulfills both these conditions. Explicitly, the motor consists of two different interacting atoms placed into a ring-shaped periodic optical potential -- an optical "bracelet" --, resulting from the interference of two counter-propagating Laguerre-Gauss laser beams. This bracelet is additionally threaded by a pulsating magnetic flux. While the first atom plays a role of a quantum "carrier", the second serves as a quantum "starter", which sets off the "carrier" into a steady rotational motion. For fixed zero-momentum initial conditions the asymptotic carrier velocity saturates to a unique, nonzero value which becomes increasingly independent on the starting time with increasing "bracelet"-size. We identify the quantum mechanisms of rectification and demonstrate that our quantum motor is able to perform useful work.Comment: simplified notations, extended figure captions; 16 pages, 6 figure

The applicability of acoustic emission method to modeling the endurance of metallic construction elements

Acoustic emission method is the most effective nondestructive inspection technique of construction elements. This paper considers the expanded applicability of acoustic emission method to modeling the damage and the remaining operational life of building structures, including the high-ductile metals. The modeling of damage accumulation was carried out to predict endurance using acoustic emission method

Numerical conjugate problem solution algorithm for fluid-deformable body system

This paper describes the numerical conjugate problem solution algorithm for fluid-deformable body system. It is based on respective subtasks according to physical principals. To solve these subtasks, independent "black box" program modules are used. These modules are connected by conjugate conditions. Fluid phase domain boundary interface is discrete movable i.e. it is not movable on the integration time step, but its position is adjusted on the next time step

Stress-strain state simulation of large-sized cable-stayed shell structures

This paper studies the opportunities for applying framed cable-stayed shell structures to generate innovative structures in civil engineering. Numerical solution methods for stress-strain state problems of these kinds of geometrically nonlinear structures were developed. Developed methods efficiency is presented by a range of large-dimensional space antenna reflectors

Spacecraft reflectors thermomechanical analysis

In this article, thermo-mechanical analysis results of the composite reflectors for the use on the geostationary Earth orbit possibility studies are described. The behavior of two different space reflector structures manufactured on composite materials is investigated. The estimates of reflecting surfaces RMS deviations for the two extreme cases orbital inclinations are presented