Search results for "SIMULATION"

The effect of a liquid CTBN rubber modifier on the thermo-kinetic parameters of an epoxy resin during a pultrusion process

2003

Abstract Rheo-kinetic behaviour of an epoxy resin, coupled with an anhydride hardener, with different CTBN liquid rubber concentration (0–15 phr), used in fibre reinforced plastics, was analysed comparing experimental data with theoretical models. The modelling of technological pultrusion process for thermoset matrix composites, developed through a numerical code realised with MATLAB, is reported, too. The model includes conduction and cure heat, degree of cure and viscosity evolution during the curing within the die. Considerable differences in process condition, using different rubber amount, are obtained. The numerical modelling of process conditions shows that the CTBN rubber presence i…

Numerical simulation of heat transfer problem for layered gypsum products exposed to fire

2018

A grain-scale model for high-cycle fatigue degradation in polycrystalline materials

2018

Abstract A grain-scale three-dimensional model for the analysis of fatigue intergranular degradation in polycrystalline materials is presented. The material microstructure is explicitly represented through Voronoi tessellations, of either convex or non-convex domains, and the mechanics of individual grains is modelled using a boundary integral formulation. The intergranular interfaces degrade under the action of cyclic loads and their behaviour is represented employing a cohesive zone model embodying a local irreversible damage parameter that evolves according to high-cycle continuum damage laws. The model is based on the use of a damage decomposition into static and cyclic contributions, a…

From Behavior of Water on Hydrophobic Graphene Surfaces to Ultra-Confinement of Water in Carbon Nanotubes

2021

In recent years and with the achievement of nanotechnologies, the development of experiments based on carbon nanotubes has allowed to increase the ionic permeability and/or selectivity in nanodevices. However, this new technology opens the way to many questionable observations, to which theoretical work can answer using several approximations. One of them concerns the appearance of a negative charge on the carbon surface, when the latter is apparently neutral. Using first-principles density functional theory combined with molecular dynamics, we develop here several simulations on different systems in order to understand the reactivity of the carbon surface in low or ultra-high confinement. …

On the blue phase structure of hydrogen-bonded liquid crystals via 19F NMR

2018

Abstract 19 F NMR spectra are simulated for blue phase I of FPHG( St 1.5 ∗ Ap 1.5 ) based on a model of a double-twisted substructure inside cylinders that form a body-centred cubic lattice. A kinetic matrix is included to describe jump processes over quarter pitch lengths. Though the lines in the NMR spectra are broad and featureless, changes in the widths and positions with temperature are well described by the blue phase model structure. The spectra in the chiral nematic N∗ phase are also simulated. Dynamics in the BP I are found to be slower than in the N∗ phase.

Photo-switching in a hybrid material made of magnetic layered double hydroxides intercalated with azobenzene molecules.

2014

Financial support from the EU (Projects HINTS FP7-263104-2 and SpinMol Advanced Grant ERC-2009-AdG-20090325), the Spanish Ministerio de Economia y Competitividad (Projects with FEDER cofinancing MAT 2009-14528-C02-01, MAT2011-22785, MAT2012-38567-C02-01, CTQ-2011-26507, Consolider-Ingenio in Molecular Nanoscience CSD2007-00010, Consolider-Ingenio 2010-Multicat CSD2009-00050, and Severo Ochoa Program SEV-2012-0267), Generalitat Valenciana (PROMETEO and ISIC-Nano programs), and VLC/Campus Microcluster "Functional Nanomaterials and Nanodevices" is gratefully acknowledged. C. M. G. thanks the Spanish MINECO for a Ramon y Cajal Fellowship (RYC-2012-10894). We also acknowledge P. Atienzar and J. …

Relaxation of wet paper by simulations and laboratory-scale experiments

2009

Numerical studies of fiber networks and experiments on wet paper show that tensile force relaxes linearly as a function of logarithmic time. Relaxation rate is faster for wet than dry paper. Simulated permanent deformation after relaxation is clearly higher than that measured in wet paper.

Multiscale modeling of polymers at interfaces

2009

A brief review of modeling and simulation methods for a study of polymers at interfaces is provided. When studying truly multiscale problems as provided by realistic polymer systems, coarse graining is practically unavoidable. In this process, degrees of freedom on smaller scales are eliminated to the favor of a model suitable for efficient study of the system behavior on larger length and time scales. We emphasize the need to distinguish between dynamic and static properties regarding the model validation. A model which accurately reproduces static properties may fail completely, when it comes to the dynamic behavior of the system. Furthermore, we comment on the use of Monte Carlo method i…

Ion conduction in the KcsA potassium channel analyzed with a minimal kinetic model.

2004

We use a model by Nelson to study the current-voltage and conductance-concentration curves of bacterial potassium channel KcsA without assuming rapid ion translocation. Ion association to the channel filter is rate controlling at low concentrations, but dissociation and transport in the filter can limit conduction at high concentration for ions other than ${\mathrm{K}}^{+}$. The absolute values of the effective rate constants are tentative but the relative changes in these constants needed to qualitatively explain the experiments should be of significance.

Assembly and Speed in Ion-Exchange-Based Modular Phoretic Microswimmers.

2017

We report an experimental study on ion-exchange-based modular microswimmers in low-salt water. Cationic ion-exchange particles and passive cargo particles assemble into self-propelling complexes, showing self-propulsion at speeds of several micrometers per second over extended distances and times. We quantify the assembly and speed of the complexes for different combinations of ion-exchange particles and cargo particles, substrate types, salt types and concentrations, and cell geometries. Irrespective of the experimental boundary conditions, we observe a regular development of the assembly shape with increasing number of cargo. Moreover, the swimming speed increases stepwise upon increasing…