1,028 research outputs found
The determination of the thermal properties of unconsolidated materials
Heat transfer in a composite cylindrical region is considered. An approximate analytical solution of the direct problem is obtained. It is shown that, beginning at the instant t > t , the relative error of the solution obtained does not exceed 1%. On the basis of this, algorithms are constructed which enable inverse problems to be solved effectively. Examples of the use of the algorithms to determine the thermal properties of unconsolidated materials are presented. © 2012 Springer Science+Business Media, Inc
Features of periodic temperature profiles in filtrating capillary porous media
The behavior of temperature profiles is examined in filtrating capillary porous media which are subjected to periodic heating. Reasons are described for amplitude shift in the temperature oscillations versus the fluid filtration rate. © 1992 Plenum Publishing Corporation
Measurement of the speed of sound by observation of the Mach cones in a complex plasma under microgravity conditions
We report the first observation of the Mach cones excited by a larger
microparticle (projectile) moving through a cloud of smaller microparticles
(dust) in a complex plasma with neon as a buffer gas under microgravity
conditions. A collective motion of the dust particles occurs as propagation of
the contact discontinuity. The corresponding speed of sound was measured by a
special method of the Mach cone visualization. The measurement results are
incompatible with the theory of ion acoustic waves. The estimate for the
pressure in a strongly coupled Coulomb system and a scaling law for the complex
plasma make it possible to derive an evaluation for the speed of sound, which
is in a reasonable agreement with the experiments in complex plasmas.Comment: 5 pages, 2 figures, 1 tabl
Freezing and melting of 3D complex plasma structures under microgravity conditions driven by neutral gas pressure manipulation
Freezing and melting of large three-dimensional complex plasmas under
microgravity conditions is investigated. The neutral gas pressure is used as a
control parameter to trigger the phase changes: Complex plasma freezes (melts)
by decreasing (increasing) the pressure. Evolution of complex plasma structural
properties upon pressure variation is studied. Theoretical estimates allow us
to identify main factors responsible for the observed behavior.Comment: Phys. Rev. Lett. (in press); 4 pages, 4 figure
A search for J^{PC}=1^{-+} exotic mesons in the pi- pi- pi+ and pi- pi0 pi0 systems
A partial wave analysis (PWA) of the pi-pi-pi+ and pi-pi0pi0 systems produced
in the reaction pi- p -> (3pi)-p at 18 GeV/c was carried out using an isobar
model assumption. This analysis is based on 3.0M pi-pi0pi0 events and 2.6M
pi-pi-pi+ events and shows production of the a2(1320), pi2(1670) and \pi(1800)
mesons. An earlier analysis of 250K pi-pi-pi+ events from the same experiment
showed possible evidence for a J^{PC}=1^{-+}$ exotic meson with a mass of 1.6
GeV/c^2 decaying into rho pi. In this analysis of a higher statistics sample of
the (3pi)- system in two charged modes we find no evidence of an exotic meson.Comment: 4 pages, 5 figures, added comment about the negative reflectivity
exotic wave
Fluid-solid phase transitions in 3D complex plasmas under microgravity conditions
Phase behavior of large three-dimensional complex plasma systems under
microgravity conditions onboard the International Space Station is
investigated. The neutral gas pressure is used as a control parameter to
trigger phase changes. Detailed analysis of structural properties and
evaluation of three different melting/freezing indicators reveal that complex
plasmas can exhibit melting by increasing the gas pressure. Theoretical
estimates of complex plasma parameters allow us to identify main factors
responsible for the observed behavior. The location of phase states of the
investigated systems on a relevant equilibrium phase diagram is estimated.
Important differences between the melting process of 3D complex plasmas under
microgravity conditions and that of flat 2D complex plasma crystals in ground
based experiments are discussed.Comment: 13 pages, 10 figures; submitted to Phys. Rev.
Dynamics of lane formation in driven binary complex plasmas
The dynamical onset of lane formation is studied in experiments with binary
complex plasmas under microgravity conditions. Small microparticles are driven
and penetrate into a cloud of big particles, revealing a strong tendency
towards lane formation. The observed time-resolved lane formation process is in
good agreement with computer simulations of a binary Yukawa model with Langevin
dynamics. The laning is quantified in terms of the anisotropic scaling index,
leading to a universal order parameter for driven systems.Comment: 4 pages, 3 figures, movies available at
http://www.mpe.mpg.de/pke/lane-formation
Hardware and Software for Determining the Thermal Properties of Rocks Under Close to Stratified Conditions
An instrument for determining the nonlinear thermal properties of rocks under natural conditions is proposed. Software is developed for processing the temperature readings, obtained from the instrument sensors, using mainly the theory of the solution of inverse problems for a parabolic-type nonlinear equation. Practical examples of the determination of the nonlinear thermal properties of some materials are presented. © 2014 Springer Science+Business Media New York
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