Search results for "THERMODYNAMICS"
showing 10 items of 2774 documents
Quantum geometry and microscopic black hole entropy
2006
9 pages, 6 figures.-- PACS nrs.: 04.60.Pp, 04.70.Dy.-- ISI Article Identifier: 000242448900013.-- Published online on Nov 28, 2006.
Unsteadiness and transition to turbulence in woven spacer filled channels for Membrane Distillation
2017
To characterize the performance of Membrane Distillation (MD) modules, channels filled with woven spacers were investigated by Computational Fluid Dynamics (including Direct Numerical Simulations and the use of the SST k-Ï turbulence model) and by parallel experiments with Thermochromic Liquid Crystals. The cases considered here regard mutually orthogonal filaments with a spacer pitch to channel height ratio P/H=2, two spacer orientations θ with respect to the main flow (0° and 45°), and bulk Reynolds numbers Re from â¼200 to â¼2000, an interval of great interest in practical MD applications. For both values of θ, CFD predicted steady-state flow for Re up to â¼300, and chaotic flow …
Effect of electrolytical hydrogenation on the thermal stability and crystallization kinetics of METGLASS MBF-50
2007
The effect of electrolytical hydrogenation on both the surface and volume crystallization kinetics and thermal stability of amorphous alloy METGLASS MBF-50 has been investigated. The surface crystallization has been investigated by the exoelectron emission (EEE) technique, whereas the volume crystallization has been followed by differential thermal analysis (DTA). It has been found that both the surface and volume crystallization of investigated material occur in two stages. The surface crystallization occurs at temperature lower and with activation energy distinctly smaller than the volume crystallization. Hydrogenation of the investigated metallic glass enhances its thermal stability by i…
Devitrification of the Kob-Andersen glass former: Competition with the locally favored structure
2018
Abstract Supercooled liquids are kinetically trapped materials in which the transition to a thermodynamically more stable state with long-range order is strongly suppressed. To assess the glass-forming abilities of a liquid empirical rules exist, but a comprehensive microscopic picture of devitrification is still missing. Here we study the crystallization of a popular model glass former, the binary Kob-Andersen mixture, in small systems. We perform trajectory sampling employing the population of the locally favored structure as order parameter. While for large population a dynamical phase transition has been reported, here we show that biasing towards a small population of locally favored s…
Damping by bulk and shear viscosity for confined acoustic phonons of a spherical virus in water
2007
International audience; A sphere-like virus in water is modeled as a homogeneous isotropic elastic continuum sphere in contact with an infinite viscous compressible Newtonian fluid. The frequencies and damping of the confined vibrational modes of the sphere are calculated for the material parameters of a virus in water. While the effects of viscosity are found to be negligible for a virus-like sphere of macroscopic size, for nanoscale viruses both the frequency and damping of the vibrational modes are significantly affected by the viscosity of the water. Furthermore, both shear viscosity and bulk viscosity play an important role.
Equilibrium and nonequilibrium many-body perturbation theory: a unified framework based on the Martin-Schwinger hierarchy
2013
We present a unified framework for equilibrium and nonequilibrium many-body perturbation theory. The most general nonequilibrium many-body theory valid for general initial states is based on a time-contour originally introduced by Konstantinov and Perel'. The various other well-known formalisms of Keldysh, Matsubara and the zero-temperature formalism are then derived as special cases that arise under different assumptions. We further present a single simple proof of Wick's theorem that is at the same time valid in all these flavors of many-body theory. It arises simply as a solution of the equations of the Martin-Schwinger hierarchy for the noninteracting many-particle Green's function with…
Thermal activated carrier transfer between InAs quantum dots in very low density samples
2010
In this work we develop a detailed experimental study of the exciton recombination dynamics as a function of temperature on QD-ensembles and single QDs in two low density samples having 16.5 and 25 dots/¼m2. We corroborate at the single QD level the limitation of the exciton recombination time in the smallest QDs of the distribution by thermionic emission (electron emission in transient conditions). A portion of these emitted carriers is retrapped again in other (larger) QDs, but not very distant from those emitting the carriers, because the process is limited by the diffusion length at the considered temperature.
Infrared Microspectroscopy study of insulin crystals at high pressure
2012
During the last years the coupling of high pressure techniques and infrared spectroscopy has proven to be a very powerful tool in the study of conformational changes of proteins. Protein unfolding and monomerization are events that are expected to take place at high pressure due to the peculiarity of pressure to shift the system towards the state that occupies the minimum volume. We observed the growth of apparently cubic crystals at a pressure of about 4 kbar, subjecting to high pressure a solution of misfolded insulin. Even if high pressure is commonly used to tune the growth rate of crystals, protein crystallization at high pressure is not a well known process and no evidences of the par…
Relations between the cohesive energy, atomic volume, bulk modulus and sound velocity in metals
2011
By analysing the experimental data available in the literature, it has been found that the bulk modulus B of metals is proportional to the cohesive energy density Ec/V. For metals which start to melt having the close packed structure A1 or A3 the proportionality factor in the forementioned correlation is distinctly greater than that for metals melting from the A2 type structure. The existence of the correlation between the bulk modulus and the cohesive energy density leads to another, hitherto unrevealed correlation between the sound velocity, cohesive energy and the molar mass of metals: u2 ~ Ec/μ.
Error and Uncertainty Analysis of the Residual Stresses Computed by Using the Hole Drilling Method
2010
: The hole-drilling method is one of the most used techniques for the experimental analysis of the residual stresses in mechanical components. For both through-thickness uniform and non-uniform residual stress distributions, its application is standardised by the ASTM E837-08. In accordance with the ASTM limitations, the analysis of uniform residual stresses, to which the present work deals with, leads in general to results with a maximum bias of about 10%. Unfortunately, in general the user does not have appropriate procedures to estimate the actual stress error; consequently, if one or more of the experimental influence parameters fall out of the corresponding standard limitations, the c…