380,688 research outputs found
Review on Multi-Scale Models of Solid-Electrolyte Interphase Formation
Electrolyte reduction products form the solid-electrolyte interphase (SEI) on
negative electrodes of lithium-ion batteries. Even though this process
practically stabilizes the electrode-electrolyte interface, it results in
continued capacity-fade limiting lifetime and safety of lithium-ion batteries.
Recent atomistic and continuum theories give new insights into the growth of
structures and the transport of ions in the SEI. The diffusion of neutral
radicals has emerged as a prominent candidate for the long-term growth
mechanism, because it predicts the observed potential dependence of SEI growth.Comment: 8 pages, 4 figure
Geometric Modeling of Cellular Materials for Additive Manufacturing in Biomedical Field: A Review
Advances in additive manufacturing technologies facilitate the fabrication of cellular materials that have tailored functional characteristics. The application of solid freeform fabrication techniques is especially exploited in designing scaffolds for tissue engineering. In this review, firstly, a classification of cellular materials from a geometric point of view is proposed; then, the main approaches on geometric modeling of cellular materials are discussed. Finally, an investigation on porous scaffolds fabricated by additive manufacturing technologies is pointed out. Perspectives in geometric modeling of scaffolds for tissue engineering are also proposed
Review of the Synergies Between Computational Modeling and Experimental Characterization of Materials Across Length Scales
With the increasing interplay between experimental and computational
approaches at multiple length scales, new research directions are emerging in
materials science and computational mechanics. Such cooperative interactions
find many applications in the development, characterization and design of
complex material systems. This manuscript provides a broad and comprehensive
overview of recent trends where predictive modeling capabilities are developed
in conjunction with experiments and advanced characterization to gain a greater
insight into structure-properties relationships and study various physical
phenomena and mechanisms. The focus of this review is on the intersections of
multiscale materials experiments and modeling relevant to the materials
mechanics community. After a general discussion on the perspective from various
communities, the article focuses on the latest experimental and theoretical
opportunities. Emphasis is given to the role of experiments in multiscale
models, including insights into how computations can be used as discovery tools
for materials engineering, rather than to "simply" support experimental work.
This is illustrated by examples from several application areas on structural
materials. This manuscript ends with a discussion on some problems and open
scientific questions that are being explored in order to advance this
relatively new field of research.Comment: 25 pages, 11 figures, review article accepted for publication in J.
Mater. Sc
Thermophysical Phenomena in Metal Additive Manufacturing by Selective Laser Melting: Fundamentals, Modeling, Simulation and Experimentation
Among the many additive manufacturing (AM) processes for metallic materials,
selective laser melting (SLM) is arguably the most versatile in terms of its
potential to realize complex geometries along with tailored microstructure.
However, the complexity of the SLM process, and the need for predictive
relation of powder and process parameters to the part properties, demands
further development of computational and experimental methods. This review
addresses the fundamental physical phenomena of SLM, with a special emphasis on
the associated thermal behavior. Simulation and experimental methods are
discussed according to three primary categories. First, macroscopic approaches
aim to answer questions at the component level and consider for example the
determination of residual stresses or dimensional distortion effects prevalent
in SLM. Second, mesoscopic approaches focus on the detection of defects such as
excessive surface roughness, residual porosity or inclusions that occur at the
mesoscopic length scale of individual powder particles. Third, microscopic
approaches investigate the metallurgical microstructure evolution resulting
from the high temperature gradients and extreme heating and cooling rates
induced by the SLM process. Consideration of physical phenomena on all of these
three length scales is mandatory to establish the understanding needed to
realize high part quality in many applications, and to fully exploit the
potential of SLM and related metal AM processes
Quasi-static imaged-based immersed boundary-finite element model of human left ventricle in diastole
SUMMARY:
Finite stress and strain analyses of the heart provide insight into the biomechanics of myocardial function and dysfunction. Herein, we describe progress toward dynamic patient-specific models of the left ventricle using an immersed boundary (IB) method with a finite element (FE) structural mechanics model. We use a structure-based hyperelastic strain-energy function to describe the passive mechanics of the ventricular myocardium, a realistic anatomical geometry reconstructed from clinical magnetic resonance images of a healthy human heart, and a rule-based fiber architecture. Numerical predictions of this IB/FE model are compared with results obtained by a commercial FE solver. We demonstrate that the IB/FE model yields results that are in good agreement with those of the conventional FE model under diastolic loading conditions, and the predictions of the LV model using either numerical method are shown to be consistent with previous computational and experimental data. These results are among the first to analyze the stress and strain predictions of IB models of ventricular mechanics, and they serve both to verify the IB/FE simulation framework and to validate the IB/FE model. Moreover, this work represents an important step toward using such models for fully dynamic fluidâstructure interaction simulations of the heart
Near-infrared optical properties and proposed phase-change usefulness of transition metal disulfides
The development of photonic integrated circuits would benefit from a wider
selection of materials that can strongly-control near-infrared (NIR) light.
Transition metal dichalcogenides (TMDs) have been explored extensively for
visible spectrum opto-electronics, but the NIR properties of these layered
materials have been less-studied. The measurement of optical constants is the
foremost step to qualify TMDs for use in NIR photonics. Here we measure the
complex optical constants for select sulfide TMDs (bulk crystals of MoS2, TiS2
and ZrS2) via spectroscopic ellipsometry in the visible-to-NIR range. Through
Mueller matrix measurements and generalized ellipsometry, we explicitly measure
the direction of the ordinary optical axis. We support our measurements with
density functional theory (DFT) calculations, which agree with our measurements
and predict giant birefringence. We further propose that TMDs could find use as
photonic phase-change materials, by designing alloys that are thermodynamically
adjacent to phase boundaries between competing crystal structures, to realize
martensitic (i.e. displacive, order-order) switching.Comment: supplementary at end of document. 6 main figure
Chemistry in Disks. IX. Observations and modeling of HCO+ and DCO+ in DM Tau
We present resolved Plateau de Bure Array observations of DM Tau in lines of
HCO+ (3-2), (1-0) and DCO+ (3-2). A power-law fitting approach allowed a
derivation of column densities of these two molecules. A chemical inner hole of
~50 AU was found in both HCO+ and DCO+ with DCO+ emission extending to only 450
AU. An isotopic ratio of R_D = N(DCO+) / N(HCO+) was found to range from 0.1 at
50 AU and 0.2 at 450 AU. Chemical modeling allowed an exploration of the
sensitivity of these molecular abundances to physical parameters out with
temperature, finding that X-rays were the domination ionization source in the
HCO+ molecular region and that R_D also is sensitive to the CO depletion. The
ionization fraction, assuming a steady state system, was found to be x(e-) ~
10. Modeling suggests that HCO+ is the dominant charged molecule in the
disk but its contribution to ionization fraction is dwarfed by atmoic ions such
as C+, S+ and H+.Comment: 13 pages with 8 figures, to be published in A&A, accepted 29/12/1
The physical and chemical properties of planet forming disks
VLT instruments and ALMA have revolutionized in the past five years our view
and understanding of how disks turn into planetary systems. They provide
exquisite insights into non-axisymmetric structures likely closely related to
ongoing planet formation processes. The following cannot be a complete review
of the physical and chemical properties of disks; instead I focus on a few
selected aspects. I will review our current understanding of the physical
properties (e.g. solid and gas mass content, snow and ice lines) and chemical
composition of planet forming disks at ages of 1-few Myr, especially in the
context of the planetary systems that are forming inside them. I will highlight
recent advances achieved by means of consistent multi-wavelength studies of gas
AND dust in protoplanetary disks.Comment: accepted for IAUS345 "Origins: From the Protosun to the First Steps
of Life" proceeding
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