La prise de décision affective chez l’enfant

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Estudio en laboratorio sobre licuefacción de arena parcialmente saturada

This experimental study was designed to assess the effects of soil water saturation on the liquefaction of Hostun RF sand. Cyclic undrained triaxial tests were conducted at different soil saturation levels, as given by Skempton’s coefficient, and liquefaction potential curves constructed for each value of this coefficient. Our findings indicate that a lower soil saturation level results in the increased resistance of the sand to liquefaction, in agreement with the tendency observed in other sands. In addition, the variation in sand resistance to liquefaction produced with Skempton’s coefficient was found to be consistent with the semi-empirical relation proposed by Yang et al. (2004).Este estudio experimental fue diseñado para comprobar los efectos de la saturación de agua en suelos bajo la licuefacción de arena RF Hostun. Tests cíclicos de tipo triaxial no drenado fueron elaborados a diferentes niveles de saturación del suelo, como se obtiene por el coeficiente de Skempton, y se obtuvieron curvas de potencial de licuefacción para cada uno de los valores de este coeficiente. Nuestros resultados indican que un nivel de saturación bajo de suelo durante el incremento de la resistencia de la arena a la licuefacción, estando de acuerdo con la tendencia observada en otras arenas. Por otro lado, se observó que la variación de la resistencia de las arenas a la licuefacción producida mediante el coeficiente de Skempton es consistente con la relación semiempírica propuesta por Yang et al. (2004)

The entropy production of stationary diffusions

The entropy production rate is a central quantity in non-equilibrium statistical physics, scoring how far a stochastic process is from being time-reversible. In this paper, we compute the entropy production of diffusion processes at non-equilibrium steady-state under the condition that the time-reversal of the diffusion remains a diffusion. We start by characterising the entropy production of both discrete and continuous-time Markov processes. We investigate the time-reversal of time-homogeneous stationary diffusions and recall the most general conditions for the reversibility of the diffusion property, which includes hypoelliptic and degenerate diffusions, and locally Lipschitz vector fields. We decompose the drift into its time-reversible and irreversible parts, or equivalently, the generator into symmetric and antisymmetric operators. We show the equivalence with a decomposition of the backward Kolmogorov equation considered in hypocoercivity theory, and a decomposition of the Fokker-Planck equation in GENERIC form. The main result shows that when the time-irreversible part of the drift is in the range of the volatility matrix (almost everywhere) the forward and time-reversed path space measures of the process are mutually equivalent, and evaluates the entropy production. When this does not hold, the measures are mutually singular and the entropy production is infinite. We verify these results using exact numerical simulations of linear diffusions. We illustrate the discrepancy between the entropy production of non-linear diffusions and their numerical simulations in several examples and illustrate how the entropy production can be used for accurate numerical simulation. Finally, we discuss the relationship between time-irreversibility and sampling efficiency, and how we can modify the definition of entropy production to score how far a process is from being generalised reversible.Comment: 27 pages of main text, 7 figures, 43 pages including appendix and reference

The compilation of statistical periodicals: a semi-annual bulletin

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Phenylbiguanide-p-Sulfonic Acid as an Analytical Reagent for the Colorimetric Determination of Nickel

Author Institution: Department of Chemistry, University of Toledo, Toledo, Ohi