10 research outputs found
Self-charge and self-cycling energy storage devices with the ferroelectric 'Braga' glass electrolyte
Joana E. Oliveira, M. Helena Braga, "Self-charge and self-cycling energy storage devices with the ferroelectric 'Braga' glass electrolyte". MSE 2020, Highlight lectur
Scaling of cosmological domain wall networks with junctions
We describe the results of the largest and most accurate three-dimensional
field theory simulations of domain wall networks with junctions. We consider a
previously introduced class of models which, in the limit of large number
of coupled scalar fields, approaches the so-called `ideal' model (in terms of
its potential to lead to network frustration). We consider values of
between N=2 and N=20. In all cases we find compelling evidence for a gradual
approach to scaling, with the quantitative scaling parameters having only a
mild dependence on . These results strongly support our no-frustration
conjecture.Comment: 4 pages, 2 figure
Intelligence in Mobile Battery Applications Desk Research Report
https://www.project-albatts.eu/Media/Publications/4/Publications_4_20200930_12811.pdf
236 page
Structural Batteries: A Review
Structural power composites stand out as a possible solution to the demands of the modern transportation system of more efficient and eco-friendly vehicles. Recent studies demonstrated the possibility to realize these components endowing high-performance composites with electrochemical properties. The aim of this paper is to present a systematic review of the recent developments on this more and more sensitive topic. Two main technologies will be covered here: (1) the integration of commercially available lithium-ion batteries in composite structures, and (2) the fabrication of carbon fiber-based multifunctional materials. The latter will be deeply analyzed, describing how the fibers and the polymeric matrices can be synergistically combined with ionic salts and cathodic materials to manufacture monolithic structural batteries. The main challenges faced by these emerging research fields are also addressed. Among them, the maximum allowable curing cycle for the embedded configuration and the realization that highly conductive structural electrolytes for the monolithic solution are noteworthy. This work also shows an overview of the multiphysics material models developed for these studies and provides a clue for a possible alternative configuration based on solid-state electrolytes
The role of domain wall junctions in Carter's pentahedral model
The role of domain wall junctions in Carter's pentahedral model is
investigated both analytically and numerically. We perform, for the first time,
field theory simulations of such model with various initial conditions. We
confirm that there are very specific realizations of Carter's model
corresponding to square lattice configurations with X-type junctions which
could be stable. However, we show that more realistic realizations, consistent
with causality constraints, do lead to a scaling domain wall network with
Y-type junctions. We determine the network properties and discuss the
corresponding cosmological implications, in particular for dark energy.Comment: 6 pages, 6 figure
Understanding Domain Wall Network Evolution
We study the cosmological evolution of domain wall networks in two and three
spatial dimensions in the radiation and matter eras using a large number of
high-resolution field theory simulations with a large dynamical range. We
investigate the dependence of the uncertainty in key parameters characterising
the evolution of the network on the size, dynamical range and number of spatial
dimensions of the simulations and show that the analytic prediction compares
well with the simulation results. We find that there is ample evidence from the
simulations of a slow approach of domain wall networks towards a linear scaling
solution. However, while at early times the uncertainty in the value of the
scaling exponent is small enough for deviations from the scaling solution to be
measured, at late times the error bars are much larger and no strong deviations
from the scaling solution are found.Comment: 11 pages, 16 figure
Generalized Global Defect Solutions
We investigate the presence of defect structures in generalized models
described by real scalar field in space-time dimensions. We work with
two distinct generalizations, one in the form of a product of functions of the
field and its derivative, and the other as a sum. We search for static
solutions and study the corresponding linear stability on general grounds. We
illustrate the results with several examples, where we find stable defect
structures of modified profile. In particular, we show how the new defect
solutions may give rise to evolutions not present in the standard scenario in
higher spatial dimensions.Comment: RevTex, 10 pages, 2 figures; version to appear in EPJ
Assessing the viability of successful reconstruction of the dynamics of dark energy using varying fundamental couplings
We assess the viability of successful reconstruction of the evolution of the
dark energy equation of state using varying fundamental couplings, such as the
fine structure constant or the proton-to-electron mass ratio. We show that the
same evolution of the dark energy equation of state parameter with cosmic time
may be associated with arbitrary variations of the fundamental couplings.
Various examples of models with the same (different) background evolution and
different (the same) time variation of fundamental couplings are studied in the
letter. Although we demonstrate that, for a broad family of models, it is
possible to redefine the scalar field in such a way that its dynamics is that
of a standard quintessence scalar field, in general such redefinition leads to
the breakdown of the linear relation between the scalar field and the variation
of fundamental couplings. This implies that the assumption of a linear coupling
is not sufficient to guarantee a successful reconstruction of the dark energy
dynamics and consequently additional model dependent assumptions about the
scalar field responsible for the dark energy need to be made.Comment: 7 pages, 2 figures, published versio
Thermal activation of a ferroelectric based glass-electrolyte energy storage cell
M. Helena Braga, Joana E. Oliveira, Thermal activation of a ferroelectric based glass-electrolyte energy storage cell, MSE 2020, From: Darmstadt, Germany. Online. Keynot