scholarly journals Storage of Energy in Constrained Non-Equilibrium Systems

Entropy ◽  
2020 ◽  
Vol 22 (5) ◽  
pp. 557
Author(s):  
Yirui Zhang ◽  
Konrad Giżyński ◽  
Anna Maciołek ◽  
Robert Hołyst
Keyword(s):  
Heat Flow ◽  
Ideal Gas ◽  
Steady States ◽  
Distributed Energy ◽  
Energy Delivery ◽  
System A ◽  
Gas System ◽  
Flow Through ◽  
Matter Flow ◽  
Non Equilibrium

We study a quantity T defined as the energy U, stored in non-equilibrium steady states (NESS) over its value in equilibrium U 0 , Δ U = U − U 0 divided by the heat flow J U going out of the system. A recent study suggests that T is minimized in steady states (Phys.Rev.E.99, 042118 (2019)). We evaluate this hypothesis using an ideal gas system with three methods of energy delivery: from a uniformly distributed energy source, from an external heat flow through the surface, and from an external matter flow. By introducing internal constraints into the system, we determine T with and without constraints and find that T is the smallest for unconstrained NESS. We find that the form of the internal energy in the studied NESS follows U = U 0 ∗ f ( J U ) . In this context, we discuss natural variables for NESS, define the embedded energy (an analog of Helmholtz free energy for NESS), and provide its interpretation.

Studies of calcium-45 desaturation from kidney slices in flow-through chambers

1978 ◽  
Vol 234 (1) ◽  
pp. R34-R38
Author(s):  
T. Uchikawa ◽  
A. B. Borle
Keyword(s):  
Kinetic Parameters ◽  
Rat Kidney ◽  
Kidney Cells ◽  
Tissue Slices ◽  
Kidney Slices ◽  
System A ◽  
Order Of Magnitude ◽  
Exponential Equations ◽  
Flow Through ◽  
Best Fit

This paper describes a method to measure calcium fluxes and calcium exchangeable pools in tissue slices by continuous perifusion in flow-through chambers. 45Ca desaturation from rat kidney slices can be analyzed as in an open three-compartment catenary system. A set of equations is given to calculate all the relevant kinetic parameters from the triple exponential equations which best fit the desaturation curves. The results show that the kinetic parameters obtained in kidney slices by this new method are in the same order of magnitude as those previously observed in cultured monkey kidney cells.

scholarly journals Determining the heat flow through the cabinet walls of household refrigerating appliances

2021 ◽  
Vol 121 ◽  
pp. 235-242
Author(s):  
Andreas Paul ◽  
Elmar Baumhögger ◽  
Andreas Elsner ◽  
Lukas Moczarski ◽  
Michael Reineke ◽  
...  
Keyword(s):  
Heat Flow ◽  
Flow Through

scholarly journals Shock interactions in inviscid air and $$\hbox {CO}_2$$–$$\hbox {N}_2$$ flows in thermochemical non-equilibrium

Shock Waves ◽  
2021 ◽  
Author(s):  
C. Garbacz ◽  
W. T. Maier ◽  
J. B. Scoggins ◽  
T. D. Economon ◽  
T. Magin ◽  
...  
Keyword(s):  
Chemical Species ◽  
High Energy ◽  
Ideal Gas ◽  
Shock Interaction ◽  
Interaction Patterns ◽  
Shock Interactions ◽  
Wave Interference ◽  
Type V ◽  
The Impact ◽  
Non Equilibrium

AbstractThe present study aims at providing insights into shock wave interference patterns in gas flows when a mixture different than air is considered. High-energy non-equilibrium flows of air and $$\hbox {CO}_2$$ CO 2 –$$\hbox {N}_2$$ N 2 over a double-wedge geometry are studied numerically. The impact of freestream temperature on the non-equilibrium shock interaction patterns is investigated by simulating two different sets of freestream conditions. To this purpose, the SU2 solver has been extended to account for the conservation of chemical species as well as multiple energies and coupled to the Mutation++ library (Multicomponent Thermodynamic And Transport properties for IONized gases in C++) that provides all the necessary thermochemical properties of the mixture and chemical species. An analysis of the shock interference patterns is presented with respect to the existing taxonomy of interactions. A comparison between calorically perfect ideal gas and non-equilibrium simulations confirms that non-equilibrium effects greatly influence the shock interaction patterns. When thermochemical relaxation is considered, a type VI interaction is obtained for the $$\hbox {CO}_2$$ CO 2 -dominated flow, for both freestream temperatures of 300 K and 1000 K; for air, a type V six-shock interaction and a type VI interaction are obtained, respectively. We conclude that the increase in freestream temperature has a large impact on the shock interaction pattern of the air flow, whereas for the $$\hbox {CO}_2$$ CO 2 –$$\hbox {N}_2$$ N 2 flow the pattern does not change.

scholarly journals Matrix Product State Simulations of Non-Equilibrium Steady States and Transient Heat Flows in the Two-Bath Spin-Boson Model at Finite Temperatures

Entropy ◽  
2021 ◽  
Vol 23 (1) ◽  
pp. 77
Author(s):  
Angus J. Dunnett ◽  
Alex W. Chin
Keyword(s):  
Finite Temperature ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Steady States ◽  
Matrix Product ◽  
Open Quantum ◽  
Matrix Product State ◽  
Wide Range ◽  
Boson Model ◽  
Non Equilibrium

Simulating the non-perturbative and non-Markovian dynamics of open quantum systems is a very challenging many body problem, due to the need to evolve both the system and its environments on an equal footing. Tensor network and matrix product states (MPS) have emerged as powerful tools for open system models, but the numerical resources required to treat finite-temperature environments grow extremely rapidly and limit their applications. In this study we use time-dependent variational evolution of MPS to explore the striking theory of Tamascelli et al. (Phys. Rev. Lett. 2019, 123, 090402.) that shows how finite-temperature open dynamics can be obtained from zero temperature, i.e., pure wave function, simulations. Using this approach, we produce a benchmark dataset for the dynamics of the Ohmic spin-boson model across a wide range of coupling strengths and temperatures, and also present a detailed analysis of the numerical costs of simulating non-equilibrium steady states, such as those emerging from the non-perturbative coupling of a qubit to baths at different temperatures. Despite ever-growing resource requirements, we find that converged non-perturbative results can be obtained, and we discuss a number of recent ideas and numerical techniques that should allow wide application of MPS to complex open quantum systems.

scholarly journals The Role of Regulators in Promoting the Procurement of Flexibility Services within the Electricity Distribution System: A Survey of Seven Leading Countries

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4073 ◽  
Author(s):  
Karim L. Anaya ◽  
Michael G. Pollitt
Keyword(s):  
Distribution System ◽  
Energy Resources ◽  
Distributed Energy Resources ◽  
Distributed Energy ◽  
Collective Interest ◽  
Regulatory Changes ◽  
System A ◽  
Use Of Resources ◽  
Generating Capacity ◽  
Tariff Structure

This paper identifies and explores regulatory issues that may have an impact on the use of flexibility services by distribution utilities to solve grid constraints. This can be done by flexible distributed energy resources which can be instructed, for instance, to reduce export generating capacity or increasing consumption. We want to identify how regulation can better support the development of the future distribution utility in its role as neutral market facilitator, enabling more competition in local flexibility markets and optimal use of resources. A set of questionnaires were designed to capture the insights around important aspects of the regulation of flexibility markets (utilities’ network incentives, network tariff structure, market design for flexibility markets, etc.). These were sent to distribution utilities, energy regulators, energy marketplaces, energy associations and relevant experts from seven jurisdictions. The responses suggest a collective interest in the procurement of flexibility services by distribution utilities from distributed energy resources. New regulations, the adaptation of current rules and recent consultations reflect this. However, the amount of progress with and preferences for key regulatory changes differ across jurisdictions.

Stochastic pumping of non-equilibrium steady-states: how molecules adapt to a fluctuating environment

2018 ◽  
Vol 54 (5) ◽  
pp. 427-444 ◽  
Author(s):  
R. D. Astumian
Keyword(s):  
Steady States ◽  
Absolute Amount ◽  
Fluctuating Environment ◽  
The Absolute ◽  
Non Equilibrium

Fluctuations favour state B = (B,B′) based on kinetic asymmetry combined with moderate dissipation rather than state A = (A,A′) in which the absolute amount of dissipation is greater but where there is no kinetic asymmetry.

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