Search results for "Thermodynamic"
showing 10 items of 2971 documents
Pore scale modelling of calcite cement dissolution in a reservoir sandstone matrix
2019
E3S Web of Conferences 98, 05010 (1-5) (2019). doi:10.1051/e3sconf/20199805010
Experimental study of Si–Al substitution in calcium-silicate-hydrate (C-S-H) prepared under equilibrium conditions.
2009
International audience; C-A-S-H of varying Al/Si and Ca/(Al+Si) ratios have been prepared introducing C-S-H (Ca/Si=0.66 and 0.95) at different weight concentrations in a solution coming from the hydration of tricalcium aluminate (Ca3Al2O6) in water. XRD and EDX (TEM) analyses show that using this typical synthesise procedure, pure C-A-S-H is obtained only for calcium hydroxide concentrations below 4.5 mmol L−1. Otherwise, calcium carboaluminate or strätlingite is also present beside C-A-S-H. The tobermorite-like structure is maintained for C-A-S-H. A kinetic study has shown that the formation of C-A-S-H is a fast reaction, typically less than a few hours. The Ca/(Al+Si) ratio of C-A-S-H mat…
Third International Conference on the Biochemistry and Molecular Biology of Nitric Oxide
1998
Abstract Nitric Oxide Volume 2, No. 2, April 1998, contained abstracts for the Third International Conference on the Biochemistry and Molecular Biology of Nitric Oxide. The abstracts are not available on IDEAL.
CLASSIFICATION THEORY FOR PHASE TRANSITIONS
1993
A refined classification theory for phase transitions in thermodynamics and statistical mechanics in terms of their orders is introduced and analyzed. The refined thermodynamic classification is based on two independent generalizations of Ehrenfests traditional classification scheme. The statistical mechanical classification theory is based on generalized limit theorems for sums of random variables from probability theory and the newly defined block ensemble limit. The block ensemble limit combines thermodynamic and scaling limits and is similar to the finite size scaling limit. The statistical classification scheme allows for the first time a derivation of finite size scaling without reno…
Driven Brownian particle as a paradigm for a nonequilibrium heat bath: Effective temperature and cyclic work extraction
2017
We apply the concept of a frequency-dependent effective temperature based on the fluctuation-dissipation ratio to a driven Brownian particle in a nonequilibrium steady state. Using this system as a thermostat for a weakly coupled harmonic oscillator, the oscillator thermalizes according to a canonical distribution at the respective effective temperature across the entire frequency spectrum. By turning the oscillator from a passive "thermometer" into a heat engine, we realize the cyclic extraction of work from a single thermal reservoir, which is feasible only due to its nonequilibrium nature.
Finite-size scaling in a microcanonical ensemble
1988
The finite-size scaling technique is extended to a microcanonical ensemble. As an application, equilibrium magnetic properties of anL×L square lattice Ising model are computed using the microcanonical ensemble simulation technique of Creutz, and the results are analyzed using the microcanonical ensemble finite-size scaling. The computations were done on the multitransputer system of the Condensed Matter Theory Group at the University of Mainz.
Basic Notions of the Theory of Heat
2016
This chapter summarizes some basic notions of thermodynamics and defines the empirical variables which are needed for the description of thermodynamic systems in equilibrium. Empirical temperature and several scales used to measure temperature are defined. The so-called “zeroth law of thermodynamics” is formulated which says that systems which are in mutual equilibrium have the same temperature. Thermodynamic ensembles corresponding to different macroscopic boundary conditions are introduced and are illustrated by simple models such as the ideal gas. Also, entropy appears on the scene for a first time, both in its statistical and its thermodynamical interpretation. Gibb’s fundamental form i…
Rate Theory for Electrocatalytic Systems: Fixed Potential Formulation for General, Electron Transfer, and Proton-Coupled Electron Transfer Reactions
2019
Atomistic modeling of electrocatalytic reactions is most naturally conducted within the grand canonical ensemble (GCE) which enables fixed chemical potential calculations. While GCE has been widely adopted for modeling electrochemical and electrocatalytic thermodynamics, the electrochemical reaction rate theory within GCE is lacking. Molecular and condensed phase rate theories are formulated within microcanonical and canonical ensembles, respectively, but electrocatalytic systems described within the GCE require extension of the conventionally used rate theories for computation reaction rates at fixed electrode potentials. In this work, rate theories from (micro) canonical ensemble are gene…
Unified Rate Theory of Electrochemistry and Electrocatalysis: Fixed Potential Formulation for General, Electron Transfer, and Proton-Coupled Electron…
2019
Atomistic modeling of electrocatalytic reactions is most naturally conducted within the grand canonical ensemble (GCE) which enables fixed chemical potential calculations. While GCE has been widely adopted for modeling electrochemical and electrocatalytic thermodynamics, the electrochemical reaction rate theory within GCE is lacking. Molecular and condensed phase rate theories are formulated within microcanonical and canonical ensembles, respectively, but electrocatalytic systems described within the GCE require extension of the conventionally used rate theories for computation reaction rates at fixed electrode potentials. In this work, rate theories from (micro)canonical ensemble are gener…
Influence of Component Temperature Derivation from Dual Angle Thermal Infrared Observations on TSEB Flux Estimates Over an Irrigated Vineyard
2015
A two-source model for deriving surface energy fluxes and their soil and canopy components was evaluated using multi-angle airborne observations. In the original formulation (TSEB1), a single temperature observation, Priestley–Taylor parameterization and the vegetation fraction are used to derive the component fluxes. When temperature observations are made from different angles, soil and canopy temperatures can be extracted directly. Two dual angle model versions are compared versus TSEB1: one incorporating the Priestley–Taylor parameterization (TSEB2I) and one using the component temperatures directly (TSEB2D), for which data from airborne campaigns over an agricultural area in Spain are u…