Modernization of an experimental installation and a procedure for investigating the anisotropic viscoelastic properties of composite materials at elevated temperatures

The paper describes the process of modernizing the existing installation designed for performing long-term tests of steel and aluminum cylindrical specimens for high-temperature creep. The modernization allowed conducting experimental studies of the anisotropic strength and viscoelastic characteristics of planar composite specimens at elevated temperatures. In order to reach the objective set, a scheme for reconstructing the specimen holders in the experimental installation was proposed, as well as the method of fixing them in the installation. The developed, designed and built automatic temperature control block for the electric furnace allowed maintaining elevated temperature with a sufficiently small error during its long use and controlling the heating temperature in a given range, which was necessary for studying the mechanical properties of composite specimens, as well as regulating the heating temperature in a given range. Conducting the experimental study of the instantaneous and long-term mechanical properties demonstrated the effectiveness of the improvements made for the experimental installation, as applied to the realization of such experiments

Thermal radiation of conducting nanoparticles

The thermal radiation of small conducting particles was investigated in the region where the Stephan-Boltzmann law is not valid and strongly overestimates radiation losses. The new criterion for the particle size, at which black body radiation law fails, was formulated. The approach is based on the magnetic particle polarization, which is valid until very small sizes (cluster size) where due to drop of particle conductivity the electric polarization prevails over the magnetic one. It was also shown that the radiation power of clusters, estimated on the basis of the experimental data, is lower than that given by the Stephan-Boltzmann law.Comment: 12 pages, 5 figures, 1 tabl

УСТАНОВЛЕНИЕ ПРИЧИН РАЗРУШЕНИЯ ПАКЕТОВ ЛОПАТОК ТУРБИН ПРИ ВЫПОЛНЕНИИ СУДЕБНЫХ ЭКСПЕРТИЗ

The technique ofdetermination of rupture sources of the turbine blades packets, which can be used at performance of forensic expertise is suggested. Its distinctive feature is completeness of the account of the various factors concerning different areas of the applied physics, such as gas dynamics, heat conductivity, thermoelasticity, static and dynamic strength. The following series of calculations was made for acknowledgement of rupture sources of bladed disk. I. Calculation of a viscous compressed subsonic current. II. Calculation periodic gas-dynamic loads operating on the blades. III. Calculation of a non-stationary stress-strain state of the bladed disk under the action of periodic forces. The technique is based on use of the numerical methods of gas dynamics and dynamic strength. The steam current through a turbomachine step calculated with the help of model of the viscous, compressedfluid. The forced vibrations of the bladed disk under the action of the aerodynamic loads are analyzed by the numerical integration of the nonlinearfinite elements design model. Four cases are considered for the numerical calculations of the stress-strain state. I. The clearance in the disk slots are not accounted and the vibrations under the action ofgas-dynamic loads from ideal directing device are investigated. II. The clearance in the disk slots are not accounted and the vibrations under the action of gas- dynamic loads from defective directing device are investigated. III. The clearance in the disk slots are taken into account and the vibrations under the action of gas-dynamic loads from ideal directing device are investigated. IV. The clearance in the disk slots are taken into account and the vibrations under the action of gas-dynamic loads from defective directing device are investigated. It’s established that a source of rupture ofworking blades of a regulating step of a compartment of a high pressure of the steam turbine is damage of blades of the directing device.Запропоновано методику встановлення причин руйнування робочих лопаток, яка може використовуватися при виконанні судових інженерно-технічних експертиз. Її відмітною рисою є повнота урахування різних факторів, що належать до різних галузей прикладної фізики, таким як газодинаміка, теплопровідність, термопружність, статична й динамічна міцності. Методика ґрунтується на використанні числових методів газодинаміки й динамічної міцності. Протікання пари через ступені турбомашини розраховувалося на підставі моделі в’язкого середовища, що стискається. Для дослідження вимушених коливань облопаченого диска під дією аеродинамічних навантажень застосовувалося чисельне інтегрування нелінійної скінченно-елементної моделі конструкції

Masses of heavy baryons in the relativistic quark model

The masses of the ground state heavy baryons consisting of two light (u,d,s) and one heavy (c,b) quarks are calculated in the heavy-quark--light-diquark approximation within the constituent quark model. The light quarks, forming the diquark, and the light diquark in the baryon are treated completely relativistically. The expansion in v/c up to the second order is used only for the heavy (b and c) quarks. The diquark-gluon interaction is taken modified by the form factor describing the light diquark structure in terms of the diquark wave functions. An overall reasonable agreement of the obtained predictions with available experimental data and previous theoretical results is found.Comment: 13 pages, 2 figures, version published in Phys. Rev.

Relativistic effects in the processes of heavy quark fragmentation

In the framework based on the quasipotential method and relativistic quark model a new covariant expression for the heavy quark fragmentation amplitude to fragment into the pseudoscalar and vector S-wave heavy mesons is obtained. It contains all possible relativistic corrections including the terms connected with the transformation law of the bound state wave function to the reference frame of the moving meson. Relativistic corrections of order {\bf p}^2/m^2 to the heavy quark fragmentation distributions into (\bar c c), (\bar b c) and (\bar b b) states are calculated as functions of the longitudinal momentum fraction z and the transverse momentum p_T relative to the jet axis.Comment: 23 pages, 6 figure

Evidence for moving breathers in a layered crystal insulator at 300K

We report the ejection of atoms at a crystal surface caused by energetic breathers which have travelled more than 10^7 unit cells in atomic chain directions. The breathers were created by bombardment of a crystal face with heavy ions. This effect was observed at 300K in the layered crystal muscovite, which has linear chains of atoms for which the surrounding lattice has C_2 symmetry. The experimental techniques described could be used to study breathers in other materials and configurations.Comment: 7 pages, 3 figure

Theory of muonic hydrogen - muonic deuterium isotope shift

We calculate the corrections of orders alpha^3, alpha^4 and alpha^5 to the Lamb shift of the 1S and 2S energy levels of muonic hydrogen (mu p) and muonic deuterium (mu d). The nuclear structure effects are taken into account in terms of the proton r_p and deuteron r_d charge radii for the one-photon interaction and by means of the proton and deuteron electromagnetic form factors in the case of one-loop amplitudes. The obtained numerical value of the isotope shift (mu d) - (mu p) for the splitting (1S-2S) 101003.3495 meV can be considered as a reliable estimation for corresponding experiment with the accuracy 10^{-6}. The fine structure interval E(1S)-8E(2S) in muonic hydrogen and muonic deuterium are calculated.Comment: 22 pages, 7 figure

Muonic hydrogen ground state hyperfine splitting

Corrections of orders alpha^5, alpha^6 are calculated in the hyperfine splitting of the muonic hydrogen ground state. The nuclear structure effects are taken into account in the one- and two-loop Feynman amplitudes by means of the proton electromagnetic form factors. The modification of the hyperfine splitting part of the Breit potential due to the electron vacuum polarization is considered. Total numerical value of the 1S state hyperfine splitting 182.638 meV in the (mu p) can play the role of proper estimation for the corresponding experiment with the accuracy 30 ppm.Comment: 18 pages, Talk presented at the 11th Lomonosov Conference on Elementary Particle Physics, Moscow State University, August 200

Magnetic moment of the two-particle bound state in quantum electrodynamics

We have formulated the quasipotential method for the calculation of the relativistic and radiative corrections to the magnetic moment of the two-particle bound state in the case of particles with arbitrary spin. It is shown that the g-factors of bound particles contain $O(\alpha^2)$ terms depending on the particle spin. Numerical values for the g-factors of the electron in the hydrogen atom and deuterium are obtained.Comment: Talk presented at Nuclear Physics Department Conference "Physics of Fundamental Interactions" Russian Academy of Sciences, ITEP, Moscow, 27 November-1 December 2000. 11 pages, 1 figure uses linedraw.st

Quark-antiquark potential with retardation and radiative contributions and the heavy quarkonium mass spectra

The charmonium and bottomonium mass spectra are calculated with the systematic account of all relativistic corrections of order v^2/c^2 and the one-loop radiative corrections. Special attention is paid to the contribution of the retardation effects to the spin-independent part of the quark-antiquark potential, and a general approach to accounting for retardation effects in the long-range (confining) part of the potential is presented. A good fit to available experimental data on the mass spectra is obtained.Comment: 20 pages, revtex, 2 Postscript figure