Search results for "SIMULATION"
showing 10 items of 5095 documents
Spectroscopic ellipsometry applied to phase transitions in solids: possibilities and limitations
2009
The possibilities of in situ spectroscopic ellipsometry applied to phase transitions investigation in oxide thin films and crystals are examined in this work, along with the use of various parameters calculated from ellipsometric data (band gap energy Eg, refractive index n and surface roughness) together with the directly measured main ellipsometric angles psi and Delta, for the detection of phase transitions. The efficiency of spectroscopic ellipsometry on "surface" phase transition and its sensitivity to surface defects are also demonstrated.
Water-Hydrophobic Zeolite Systems
2012
Water intrusion-extrusion in hydrophobic microporous AFI, IFR, MTW and TON pure silica zeolites (zeosils) has been investigated through molecular dynamics (MD) simulations. It was found that intruded water volumes correlate with the free volume of the zeosil unit cells. Calculated adsorption isotherms allowed us to estimate the amounts of water intruded, and deviations from experiments (lower experimental with respect to calculated intrusion pressures) have been;explained in terms of connectivity defects in the synthesized materials. Water phase transitions in defectless zeosils occur in a narrow range at high pressure. On the basis of a simple model, we derived a thermodynamic equation tha…
Vibrational Analysis of Paraelectric–Ferroelectric Transition of LiNbO3: An Ab-Initio Quantum Mechanical Treatment
2021
FSG acknowledges the CINECA award under the ISCRA initiative (HP10BJO47B) for the availability of high-performance computing resources and support.
Polymer mixtures in confined geometries: Model systems to explore phase transitions
2005
While binary (A,B) symmetric polymer mixtures ind = 3 dimensions have an unmixing critical point that belongs to the 3d Ising universality class and crosses over to mean field behavior for very long chains, the critical behavior of mixtures confined into thin film geometry falls in the 2d Ising class irrespective of chain length. The critical temperature always scales linearly with chain length, except for strictly two-dimensional chains confined to a plane, for whichT; c ∝N; 5/8 (this unusual exponent describes the fractal contact line between segregated chains in dense melts in two spatial dimensions, d = 2). When the walls of the thin film are not neutral, but preferentially attract one …
Quine and the Contemporary Debate on Mindreading
2012
Abstract The paper examines some of the questions emerging from the debate on mindreading regarding Quine’s legacy and contribution to a new agenda on the issue. Since mindreading is an exercise in folk-psychology, a) which role folk psychology has to play according to Quine? b) was Quine’s account of mindreading closer to theory-theory, simulation theory or hybrid theory? c) was Quine a rationality theorist? d) are hybrid-theory and rationality theory incompatible as many would suggest? On the score of the answers to these questions, the paper tries to suggest a Quinean inspired blend of rationality-based and hybrid view-based strategies to explain mindreading.
Subsurface treatment of a contact subjected to a hertz pressure
2013
Abstract The study proposes an approach allowing the favorable modification of the stresses field of a structure subjected to a Hertzian contact. It is based on the study of a classic Hertzian contact in the presence of subsurface circular defects. The idea is to limit the field of tangential stresses without large increasing of the global stress (Von Mises) of the system. The location of the defects is made according to the mechanical parameters of the contact (Fn, has, z). The results of the numerical calculations (FEM) are compared with photoelastic measurements and highlight an excellent correlation. The location of the defect on the symmetry axis (x=0) is the dominating parameter for t…
A critical assessment of automatic photoelastic methods for the analysis of edge residual stresses in glass
2014
The measurement of residual stresses is of great importance in the glass industry. The analysis of residual stresses in the glass is usually carried out by photoelastic methods since the glass is a photoelastic material. This article considers the determination of membrane residual stresses of glass plates by digital photoelasticity. In particular, it presents a critical assessment concerning the automated methods based on gray-field polariscope, spectral content analysis, phase shifting, RGB photoelasticity, “test fringes” methods and “tint plate” method. These methods can effectively automate manual methods currently specified in some standards.
Automated photoelasticity in white light: Influence of quarter-wave plates
1995
This paper deals with the influence of optical retarders on the isochromatic fringes obtained by automated white light photoelasticity using methods such as those based on spectral content analysis (SCA) and on primary colour (red, green and blue) analysis. In the following the light intensity equations of dark- and light-field polariscopes with both crossed and parallel optical retarders are reviewed. In particular, it is shown that the retardance error of the quarter-wave plates produces an attenuation of the maximum intensity in dark field and an increase of minimum intensity in light field. Experimental evidence of the influence of optical retarders is also shown.
A review of automated methods for the collection and analysis of photoelastic data
1998
Photoelasticity is one of the most widely used full-field methods for experimental stress analysis. However, the collection of photoelastic parameters can be a long and tedious process. The advent of automated photoelastic systems has allowed the experimentalists to speed up the rate of analysis and to perform more complex investigations. This paper provides a survey of recent methods of automated photoelasticity developed in the last 20 years, i.e. methods of the fringe centres, half-fringe photoelasticity, phase-stepping photoelasticity, methods based on the Fourier transform, spectral content analysis (SCA) and RGB (red, green, blue) photoelasticity.
Nitrogen-doped carbon dots embedded in a SiO2 monolith for solid-state fluorescent detection of Cu2+ ions
2017
We describe the simple fabrication of SiO2 sol-gel monoliths embedding highly luminescent carbon nanodots (CDs) sensitive to metal ions. The pristine CDs we synthesize display an intense dual emission consisting in two fluorescence bands in the green and violet region, and we demonstrate that this photoluminescence is substantially unchanged when the dots are incorporated in the SiO2 matrix. The emission of these CDs is quenched by interactions with Cu2+ ions, which can be used to detect these ions with a detection limit of 1 μM. The chromophores remain accessible to diffusing Cu2+ ions even after embedding CDs in the sol-gel monolith, where their detection capabilities are preserved. Such …