Search results for "THERMODYNAMICS"
showing 10 items of 2774 documents
Surface tension and density of binary mixtures of monoalcohols, water and acetonitrile: equation of correlation of the surface tension
2009
Measurements of the surface tension (σ) and density (ρ) of binary mixtures of monoalcohols, water and acetonitrile at 298.15 K and at atmospheric pressure, as a function of mole fraction (x) have been made. The experimental values of the deviation of surface tension and the excess of molar volume (Δσ, V E) have been correlated by the Redlich–Kister equation. An empirical correlation equation is presented for the study of the surface tension of these mixtures, and comparisons are made of the experimental values of surface tension versus those obtained with the correlation equation and with other models of correlation. Finally, with the purpose of corroborating the validity of the correlation…
Viscosity and density of binary mixtures of alcohols and polyols with three carbon atoms and water: equation for the correlation of viscosities of bi…
2009
Measurements have been made of the viscosity and density of binary mixtures of alcohols and polyols with three carbon atoms and water at 298.15 K and at atmospheric pressure, as a function of the mole fraction. Fits have been made of the experimental values corresponding to the excesses of molar volume (V E), the deviations of viscosity (Δη), and the excesses of Gibbs free energy of activation (G* E), by means of the Redlich–Kister equation. A new correlation equation is presented for studying the viscosity of such mixtures, and comparisons are made of the experimental values of viscosity versus the values obtained by means of the mentioned equation and the models of Heric and McAllister. L…
First-principles nonequilibrium Green's-function approach to transient photoabsorption: Application to atoms
2015
We put forward a first-principle NonEquilibrium Green's Function (NEGF) approach to calculate the transient photoabsorption spectrum of optically thin samples. The method can deal with pump fields of arbitrary strength, frequency and duration as well as for overlapping and nonoverlapping pump and probe pulses. The electron-electron repulsion is accounted for by the correlation self-energy, and the resulting numerical scheme deals with matrices that scale quadratically with the system size. Two recent experiments, the first on helium and the second on krypton, are addressed. For the first experiment we explain the bending of the Autler-Townes absorption peaks with increasing the pump-probe d…
A Mechano-Chemical Coupling for Hydrogen Diffusion in Metals Based on a Thermodynamic Approach
2014
Hydrogen diffusion in metals is still an ongoing topic of research due to its technical relevance (hydrogen embrittlement, hydrogen storage...). In the last decades, significant progress in understanding the time evolution of the hydrogen concentration in solids was completed. This paper presents a modeling of hydrogen diffusion with a general and thermodynamically based diffusion concept coupled with mechanical and chemical aspects. This model was previously used to simulate the oxidation of a metal [1][2]. This concept has been upgraded to offer a thoroughly macroscopic behavior law used to simulate hydrogen diffusion in metal parts under mechanical loadings. The thermodynamic approach of…
Neural Network Approach for Characterizing Structural Transformations by X-Ray Absorption Fine Structure Spectroscopy
2018
AIF acknowledge support by the US Department of Energy, Office of Basic Energy Sciences under Grant No. DE-FG02 03ER15476. AIF acknowledges support by the Laboratory Directed Research and Development Program through LDRD 18-047 of Brookhaven National Laboratory under U.S. Department of Energy Contract No. DE-SC0012704 for initiating his research in machine learning methods. The help of the beamline staff at ELETTRA (project 20160412) synchrotron radiation facility is acknowledged. RMC-EXAFS and MD-EXAFS simulations were performed on the LASC cluster-type computer at Institute of Solid State Physics of the University of Latvia.
Detection of steering direction using EEG recordings based on sample entropy and time-frequency analysis.
2016
Monitoring driver's intentions beforehand is an ambitious aim, which will bring a huge impact on the society by preventing traffic accidents. Hence, in this preliminary study we recorded high resolution electroencephalography (EEG) from 5 subjects while driving a car under real conditions along with an accelerometer which detects the onset of steering. Two sensor-level analyses, sample entropy and time-frequency analysis, have been implemented to observe the dynamics before the onset of steering. Thus, in order to classify the steering direction we applied a machine learning algorithm consisting of: dimensionality reduction and classification using principal-component-analysis (PCA) and sup…
Angular dependence of the emissivity of bare soils in the thermal infrared
2009
Emissivity is one of the main factors to take into account when studying processes that take place in the Earth surface by using radiance measurements in the thermal infrared, such as surface energy balance, land surface temperature (LST) retrieval, classification of different types of surface, etc. For this reason it is necessary to study the factors that can influence the emissivity. The present work evaluates one of these factors: the variation of the emissivity with the zenithal observation angle over bare soils, specifically the variation of the relative emissivity calculated from measurements of radiances, almost simultaneous, at nadir (0o) and at a certain angle (Θ). The measurements…
The helicity matching approach to heavy hadron form factors
1991
Abstract I discuss the helicity matching approach to current-induced transitions among heavy hadrons. This approach provides a simple and intuitively appealing access to the calculation of heavy hadron form factors which is entirely equivalent to the approach of Isgur and Wise and other authors, who use different techniques to obtain the same results. We work out explicit examples in the meson and baryon sectors and discuss possible approximations to the most general approach and some of their implications for future experiments.
Ab Initio Study of BiFeO3: Thermodynamic Stability Conditions
2015
BiFeO3 is investigated intensively, mainly as a multiferroic material. In this paper, the state-of-the-art ab initio hybrid functional approach with atomic basis sets was employed for a study of the stability range of BiFeO3 with respect to its decomposition into binary oxides and elementary metals, as a function of temperature and oxygen partial pressure. The calculated atomic and electronic structure of BiFeO3 was compared with previous LDA+U calculations using plane-wave basis sets. Based on performed calculations, the phase diagram was constructed, which allows us to predict the stability region of stoichiometric BiFeO3.
Sizing of ICE and Lithium-ion battery for series hybrid vehicle over life cycle with battery aging
2013
This paper presents a method to evaluate the volume and weight of the internal combustion engine (ICE) and lithium-ion battery for a series hybrid vehicle that allows to minimize the mean consumption over system life. Individual driving cycles of the car over a total distance of 100 000 km are simulated. The ICE and battery dimensions are approximated; the fuel consumption is evaluated using a general approach. Lithium-ion battery is described including capacity fading and the energy split between ICE and battery system is evaluated using an heuristic approach. Results show a decrease of mean fuel consumption down to 5.1 L/100km.