945 research outputs found
Thermodynamics and its CALPHAD Modeling: Review, State of the Art, and Perspectives
Thermodynamics is a science concerning the state of a system, whether it is
stable, metastable, or unstable. The combined law of thermodynamics derived by
Gibbs about 150 years ago laid the foundation of thermodynamics. In Gibbs
combined law, the entropy production due to internal processes was not
included, and the 2nd law was thus practically removed from the Gibbs combined
law, so it is only applicable to systems under equilibrium. Gibbs further
derived the classical statistical thermodynamics in terms of the probability of
configurations in a system. With the quantum mechanics (QM) developed, the
QM-based statistical thermodynamics was established and connected to classical
statistical thermodynamics at the classical limit as shown by Landau. The
development of density function theory (DFT) by Kohn and co-workers enabled the
QM prediction of properties of the ground state of a system. On the other hand,
the entropy production due to internal processes in non-equilibrium systems was
studied separately by Onsager and Prigogine and co-workers. The digitization of
thermodynamics was developed by Kaufman in the framework of the CALPHAD
modeling of individual phases. Our recently termed zentropy theory integrates
DFT and statistical mechanics through the replacement of the internal energy of
each individual configuration by its DFT-predicted free energy. Furthermore,
through the combined law of thermodynamics with the entropy production as a
function of internal degrees of freedom, it is shown that the kinetic
coefficient matrix of independent internal processes is diagonal with respect
to the conjugate potentials in the combined law, and the cross phenomena
represented by the phenomenological Onsager reciprocal relationships are due to
the dependence of the conjugate potential of the molar quantity in a flux on
nonconjugate potentials
Bond graph modelling of exergy in integrated energy systems
Ph. D. Thesis.Integrated municipal or district energy systems are one facet of the effort to support
sustainable energy systems that work towards reducing anthropogenic climate change
emissions. Current energy systems — including electricity, heat, and cooling — operate mostly independently, under the control of domain-distinct industries and regulatory
bodies. Operating these separate systems in a cooperative or integrated manner promises
improvements in efficiency, the ability of networks to absorb renewable energy sources
and storage, emissions reductions and community-based benefits.
The nature of district energy systems is that they cannot easily be modified or built
upon without severe disruption to the communities they serve, so assessments of their
behaviour and performance caused by potential changes must be modelled. This thesis
investigates what methods can model integrated energy systems and develops a bond
graph-based approach to constructing a fully-integrated system model. Although energy
based methods for integrated energy system modelling exist, this thesis demonstrates that
exergy can form the basis of integrated energy system models. Exergy being a measure
of the usefulness of energy allows the equivalence of energy domains in a single model
form, permitting development of a genuine, physically-founded integrated energy system
model.
An integrated model of a residential district supplied by heat and electrical networks,
based on a real UK urban area, is demonstrated in OpenModelica using the developed
modelling approach. The concept of an exergy storage device is introduced to provide
a mechanism for mediating energy flows between the networks. The model is used to
evaluate the performance of the test network, using trial cases to investigate how transferring exergy between energy domains through the mediating storage affects the overall
system energy and exergy efficiencies. Operational regimes that transfer energy from the
electrical to the thermal sub-system using the mediating storage are found to improve the
exergy efficiency of the system.Newcastle University, Siemen
Chemical Kinetics
Chemical Kinetics relates to the rates of chemical reactions and factors such as concentration and temperature, which affects the rates of chemical reactions. Such studies are important in providing essential evidence as to the mechanisms of chemical processes. The book is designed to help the reader, particularly students and researchers of physical science, understand the chemical kinetics mechanics and chemical reactions. The selection of topics addressed and the examples, tables and graphs used to illustrate them are governed, to a large extent, by the fact that this book is aimed primarily at physical science (mainly chemistry) technologists. Undoubtedly, this book contains "must read" materials for students, engineers, and researchers working in the chemistry and chemical kinetics area. This book provides valuable insight into the mechanisms and chemical reactions. It is written in concise, self-explanatory and informative manner by a world class scientists in the field
Computational Modeling of the Time-dependent Behavior of Cementitious Materials
Finite element procedures combined with microstructure development modeling are integrated to quantitatively predict the viscoelastic/viscoplastic relaxation of cement paste due to intrinsic calcium silicate hydrate viscoelasticity/viscoplasticity and microstructure evolution. The combined models are implemented in a computational routine to predict time-dependent stress and strain fields in cement paste. Besides predicting the time-dependent viscoelastic/viscoplastic properties of cement paste, the early-age desiccation shrinkage of cement paste is also computationally simulated utilizing this modeling approach. The model simulations suggest that inherent viscoelastic deformation caused by calcium silicate hydrate might not necessarily be the primary mechanism leading to the overall early-age time-dependent behavior of cement paste. The effect of time-dependent dissolution of load-bearing phases due to either the hydration reaction or the application of stress/strain can be substantial and should be considered as a significant mechanism for the apparent viscoelasticity/viscoplasticity of cement paste
Statistical physics approaches to the complex Earth system
Global climate change, extreme climate events, earthquakes and their
accompanying natural disasters pose significant risks to humanity. Yet due to
the nonlinear feedbacks, strategic interactions and complex structure of the
Earth system, the understanding and in particular the predicting of such
disruptive events represent formidable challenges for both scientific and
policy communities. During the past years, the emergence and evolution of Earth
system science has attracted much attention and produced new concepts and
frameworks. Especially, novel statistical physics and complex networks-based
techniques have been developed and implemented to substantially advance our
knowledge for a better understanding of the Earth system, including climate
extreme events, earthquakes and Earth geometric relief features, leading to
substantially improved predictive performances. We present here a comprehensive
review on the recent scientific progress in the development and application of
how combined statistical physics and complex systems science approaches such
as, critical phenomena, network theory, percolation, tipping points analysis,
as well as entropy can be applied to complex Earth systems (climate,
earthquakes, etc.). Notably, these integrating tools and approaches provide new
insights and perspectives for understanding the dynamics of the Earth systems.
The overall aim of this review is to offer readers the knowledge on how
statistical physics approaches can be useful in the field of Earth system
science
Condensed-Matter-Principia Based Information & Statistical Measures
This book summarizes the efforts of ten papers collected by the Special Issue "Condensed-Matter-Principia Based Information & Statistical Measures: From Classical to Quantum". It calls for papers which deal with condensed-matter systems, or their interdisciplinary analogs, for which well-defined classical–statistical vs. quantum information measures can be inferred while based on the entropy concept. The contents have mainly been rested upon objectives addressed by an international colloquium held on October 2019, in UTP Bydgoszcz, Poland (see http://zmpf.imif.utp.edu.pl/rci-jcs/rci-jcs-4/), with an emphasis placed on the achievements of Professor Gerard Czajkowski, who commenced his research activity with open diffusion–reaction systems under the supervision of Roman S. Ingarden (Toruń), a father of Polish synergetics, and original thermodynamic approaches to self-organization. The active cooperation of Professor Czajkowski, mainly with German physicists (Friedrich Schloegl, Aachen; Werner Ebeling, Berlin), ought to be highlighted. In light of this, a development of his research, as it has moved from statistical thermodynamics to solid state theory, pursued in terms of nonlinear solid-state optics (Franco Bassani, Pisa), and culminated very recently with large quasiparticles termed Rydberg excitons, and their coherent interactions with light, is worth delineating
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