4,629 research outputs found
Emergence of the second law out of reversible dynamics
Abstract If one demystifies entropy the second law of thermodynamics comes out as an emergent property entirely based on the simple dynamic mechanical laws that govern the motion and energies of system parts on a micro-scale. The emergence of the second law is illustrated in this paper through the development of a new, very simple and highly efficient technique to compare time-averaged energies in isolated conservative linear large scale dynamical systems. Entropy is replaced by a notion that is much more transparent and more or less dual called ectropy. Ectropy has been introduced before but we further modify the notion of ectropy such that the unit in which it is expressed becomes the unit of energy. The second law of thermodynamics in terms of ectropy states that ectropy decreases with time on a large enough time-scale and has an absolute minimum equal to zero. Zero ectropy corresponds to energy equipartition. Basically we show that by enlarging the dimension of an isolated conservative linear dynamical system and the dimension of the system parts over which we consider time-averaged energy partition, the tendency towards equipartition increases while equipartition is achieved in the limit. This illustrates that the second law is an emergent property of these systems. Finally from our large scale linear dynamic model we clarify Loschmidt’s paradox concerning the irreversible behavior of ectropy obtained from the reversible dynamic laws that govern motion and energy at the micro-scal
Evolutionary and Pulsational Properties of Ultra-massive White Dwarfs. The Role of Oxygen-Neon Phase Separation.
The 21st European Workshop on White Dwarfs was held in Austin, TX from July 23rd to 27th of 2018Ultra-massive hydrogen-rich white dwarf stars are
expected to harbour oxygen/neon cores resulting
from semidegenerate carbon burning when the
progenitor star evolves through the super asymptotic
giant branch (S-AGB) phase. These stars are
expected to be crystallized by the time they reach
the ZZ Ceti domain. We show that crystallization
leads to a phase separation of oxygen and neon in
the core of ultra-massive white dwarfs, which impacts
markedly the pulsational properties, thus offering
a unique opportunity to infer and test the
process of crystallization and phase separation in
white dwarf stars.Astronom
Filter Cleaning Using Gas Injection
A filter cleaning process using gas injection is considered. An estimate for the minimum mass flow rate out of the gas injector and the corresponding injector/filter geometry is found. The estimates are based on a similarity solution for a free turbulent jet. The minimum mass flow rate and geometry is worked out for a specific example
Faune du Calcaire carbonifère de la Belgique. III (Avec un atlas de 21 planches in-folio). Gastéropodes
Faune du Calcaire carbonifère de la Belgique. IV (Avec un atlas de 36 planches in-folio). Gastéropodes (suite et fin)
Strategic and tactical decision making in a dedicated transportation service in the chemical cluster of Rotterdam:a business model
Faune du Calcaire carbonifère de la Belgique. V (Avec un atlas de 41 planches in-folio). Lamellibranches
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