Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Non-equilibrium systems

Slade, L. and Levine, H. A food polymer science approach to structure-property relationships in aqueous food systems non-equilibrium behavior of carbohydrate-water systems. Water Relationships in Foods, H. Levine and L. Slade, eds.. Plenum Publisher Company, New York, pp. 29, 1991. [Pg.612]

It may be noted that in real systems, non-equilibrium phenomena are much more complex which involve multi-processes and complex coupling. [Pg.24]

When a system is not in equilibrium, the mathematical description of fluctuations about some time-dependent ensemble average can become much more complicated than in the equilibrium case. However, starting with the pioneering work of Einstein on Brownian motion in 1905, considerable progress has been made in understanding time-dependent fluctuation phenomena in fluids. Modem treatments of this topic may be found in the texts by Keizer [21] and by van Kampen [22]. Nevertheless, the non-equilibrium theory is not yet at the same level of rigour or development as the equilibrium theory. Here we will discuss the theory of Brownian motion since it illustrates a number of important issues that appear in more general theories. [Pg.687]

Another possibility is that a system may be held in a constrained equilibrium by external forces and thus be in a non-equilibrium steady state (NESS). In this case, the spatio-temporal correlations contain new ingredients, which are also exemplified in section A3.3.2. [Pg.716]

In the other class of experiments, the system, in equilibrium at t = -co, is adiabatically perturbed to a non-eqiiilibriiim state which gets fiilly switched on by t = 0, through the field, t l — S(tAr c t < 0, widi e... [Pg.719]

There are many examples in nature where a system is not in equilibrium and is evolving in time towards a thennodynamic equilibrium state. (There are also instances where non-equilibrium and time variation appear to be a persistent feature. These include chaos, oscillations and strange attractors. Such phenomena are not considered here.)... [Pg.731]

In spectroscopy it is common for transitions to be observed as absorptive lines because the Boltzmaim distribution, at equilibrium, ensures a higher population of the lower state than the upper state. Examples where emission is observed, which are by definition non-equilibrium situations, are usually cases where excess population is created in the higher level by infiising energy into the system from an external source. [Pg.1591]

Bain A D and Martin J S 1978 FT NMR of non-equilibrium states of oomplex spin systems I. A Liouville spaoe desoription J. Magn. Reson. 29 125-35... [Pg.2113]

Most chemically reacting systems tliat we encounter are not tliennodynamically controlled since reactions are often carried out under non-equilibrium conditions where flows of matter or energy prevent tire system from relaxing to equilibrium. Almost all biochemical reactions in living systems are of tliis type as are industrial processes carried out in open chemical reactors. In addition, tire transient dynamics of closed systems may occur on long time scales and resemble tire sustained behaviour of systems in non-equilibrium conditions. A reacting system may behave in unusual ways tliere may be more tlian one stable steady state, tire system may oscillate, sometimes witli a complicated pattern of oscillations, or even show chaotic variations of chemical concentrations. [Pg.3054]

Analogous considerations apply to spatially distributed reacting media where diffusion is tire only mechanism for mixing chemical species. Under equilibrium conditions any inhomogeneity in tire system will be removed by diffusion and tire system will relax to a state where chemical concentrations are unifonn tliroughout tire medium. However, under non-equilibrium conditions chemical patterns can fonn. These patterns may be regular, stationary variations of high and low chemical concentrations in space or may take tire fonn of time-dependent stmctures where chemical concentrations vary in botli space and time witli complex or chaotic fonns. [Pg.3054]

The first term represents the forces due to the electrostatic field, the second describes forces that occur at the boundary between solute and solvent regime due to the change of dielectric constant, and the third term describes ionic forces due to the tendency of the ions in solution to move into regions of lower dielectric. Applications of the so-called PBSD method on small model systems and for the interaction of a stretch of DNA with a protein model have been discussed recently ([Elcock et al. 1997]). This simulation technique guarantees equilibrated solvent at each state of the simulation and may therefore avoid some of the problems mentioned in the previous section. Due to the smaller number of particles, the method may also speed up simulations potentially. Still, to be able to simulate long time scale protein motion, the method might ideally be combined with non-equilibrium techniques to enforce conformational transitions. [Pg.75]

Monte Carlo simulations are commonly used to compute the average thermodynamic properties of a molecule or a system of molecules, and have been employed extensively in the study of the structure and equilibrium properties of liquids and solutions. Monte Carlo methods have also been used to conduct conformational searches under non-equilibrium conditions. [Pg.95]

Because of this heat generation, when adsorption takes place in a fixed bed with a gas phase flowing through the bed, the adsorption becomes a non-isothermal, non-adiabatic, non-equilibrium time and position dependent process. The following set of equations defines the mass and energy balances for this dynamic adsorption system [30,31] ... [Pg.248]


See other pages where Non-equilibrium systems is mentioned: [Pg.516]    [Pg.118]    [Pg.28]    [Pg.998]    [Pg.268]    [Pg.445]    [Pg.105]    [Pg.162]    [Pg.516]    [Pg.118]    [Pg.28]    [Pg.998]    [Pg.268]    [Pg.445]    [Pg.105]    [Pg.162]    [Pg.378]    [Pg.378]    [Pg.388]    [Pg.390]    [Pg.436]    [Pg.664]    [Pg.696]    [Pg.719]    [Pg.731]    [Pg.731]    [Pg.731]    [Pg.733]    [Pg.756]    [Pg.929]    [Pg.929]    [Pg.1499]    [Pg.2383]    [Pg.2615]    [Pg.2668]    [Pg.2859]    [Pg.3055]    [Pg.16]    [Pg.39]    [Pg.40]    [Pg.349]    [Pg.396]    [Pg.234]    [Pg.180]    [Pg.5]    [Pg.90]   
See also in sourсe #XX -- [ Pg.32 ]




SEARCH



Autowaves in non-equilibrium extended systems

Dynamics of a Non-equilibrium Electrochemical System

NON-EQUILIBRIUM PHENOMENA IN CONTINUOUS SYSTEMS

Non-Equilibrium Discharge Conditions and Gas-Phase Plasma-Chemical Processes in the Systems Applied for Synthesis of Diamond Films

Non-equilibrium

Non-equilibrium Molecular Dynamics Simulations of Coarse-Grained Polymer Systems

Non-equilibrium electrochemical systems

Non-equilibrium natural systems

Self-organization in non equilibrium systems

Systems equilibrium

© 2024 chempedia.info