Search results for "Neural Networks"
showing 10 items of 599 documents
Size effects in micro- and nanoscale indentation
2006
Abstract The indentation size effect (ISE) has been studied in single crystals, polycrystals and amorphous solids using the Vickers microhardness test. The ISE is clearly present in single crystals but is absent in fine-grained polycrystals. A size-dependent hardness for amorphous solids is observed only in the sub-micrometre surface layer. The behaviour of the ISE in single crystals for micro- and nanoindentation is compared. Estimates of the surface hardness are made by the extrapolation of the experimental hardness–indentation depth curves. The extrapolated hardness in the surface region reaches values corresponding to the theoretical shear strength. The results confirm the multifarious …
Monte Carlo modelling of the polymer glass transition
1993
We are proposing a lattice model with chemical input for the computer modelling of the polymer glass transition. The chemical input information is obtained by a coarse graining procedure applied to a microscopic model with full chemical detail. We use this information on Bisphenol-A-Polycarbonate to predict it's Vogel-Fulcher temperature out of a dynamic Monte Carlo Simulation. The microscopic structure of the lattice model is that of a genuine amorphous material, and the structural relaxation obeys the time temperature superposition.
Role of thermal history on quiescent cold crystallization of PET
2002
8 pags., 9 figs.
Artificial neural network based particle size prediction of polymeric nanoparticles.
2017
Particle size of nanoparticles and the respective polydispersity are key factors influencing their biopharmaceutical behavior in a large variety of therapeutic applications. Predicting these attributes would skip many preliminary studies usually required to optimize formulations. The aim was to build a mathematical model capable of predicting the particle size of polymeric nanoparticles produced by a pharmaceutical polymer of choice. Polymer properties controlling the particle size were identified as molecular weight, hydrophobicity and surface activity, and were quantified by measuring polymer viscosity, contact angle and interfacial tension, respectively. A model was built using artificia…
Aging as dynamics in configuration space
1999
The relaxation dynamics of many disordered systems, such as structural glasses, proteins, granular materials or spin glasses, is not completely frozen even at very low temperatures. This residual motion leads to a change of the properties of the material, a process commonly called aging. Despite recent advances in the theoretical description of such aging processes, the microscopic mechanisms leading to the aging dynamics are still a matter of dispute. In this Letter we investigate the aging dynamics of a simple glass former by means of molecular dynamics computer simulation. Using the concept of the inherent structure we give evidence that aging dynamics can be understood as a decrease of …
Magnetic properties of Cd–Mg–Tb quasicrystal
2004
Abstract The magnetic properties of an icosahedral Cd–Mg–Tb quasicrystal were studied by dc magnetization and thermoremanent magnetization time decay measurements. An unusual temperature dependence of the susceptibility below freezing temperature can be attributed to the inhomogeneous sample structure. In addition to the quasicrystalline portion which exhibits a spin-glass transition at 12.5 K a part of the sample behaves like a paramagnet. During aging of the sample in air the spin-glass part transforms into the paramagnetic one. The linear M ∝ H dependence of the thermoremanent magnetization time decay on magnetic field is quite different as compared to canonical spin glasses.
Coarsened Lattice Model for Random Granular Systems
1998
In random systems consisting of grains with size distributions the transport properties are difficult to explore by network models. However, the concentration dependence of effective conductivity and its critical properties can be considered within coarsened lattice model proposed that takes into account information from experimentally known size histograms. For certain classes of size distributions the specific local arrangements of grains can induce either symmetrical or unsymmetrical critical behaviour at two threshold concentrations. Using histogram related parameters the non-monotonic behaviour of the conductor-insulator and conductor-superconductor threshold is demonstrated.
Slow dynamics in ion-conducting sodium silicate melts: Simulation and mode-coupling theory
2005
A combination of molecular-dynamics (MD) computer simulation and mode-coupling theory (MCT) is used to elucidate the structure-dynamics relation in sodium-silicate melts (NSx) of varying sodium concentration. Using only the partial static structure factors from the MD as an input, MCT reproduces the large separation in relaxation time scales of the sodium and the silicon/oxygen components. This confirms the idea of sodium diffusion channels which are reflected by a prepeak in the static structure factors around 0.95 A^-1, and shows that it is possible to explain the fast sodium-ion dynamics peculiar to these mixtures using a microscopic theory.
Light-induced ionic processes in optical oxide glasses
1991
Abstract The density of optical glasses is changed by the influence of light capable of generating color centers in these materials. Such defect generation is not only an electronic process, but an atomic displacement is also necessary. The strong localization of electronic and vibrational excitations in the glass network leads to the high efficiency of sub-threshold defect generation. Secondary ionic processes lead to the changes of basic glass properties (light refractive index, density, mechanical strength, etc.); thus, it is possible to use optical glasses as light detectors for appropriate wavelengths.
Statics and dynamics of colloid-polymer mixtures near their critical point of phase separation: A computer simulation study of a continuous Asakura–O…
2008
We propose a new coarse-grained model for the description of liquid-vapor phase separation of colloid-polymer mixtures. The hard-sphere repulsion between colloids and between colloids and polymers, which is used in the well-known Asakura-Oosawa (AO) model, is replaced by Weeks-Chandler-Anderson potentials. Similarly, a soft potential of height comparable to thermal energy is used for the polymer-polymer interaction, rather than treating polymers as ideal gas particles. It is shown by grand-canonical Monte Carlo simulations that this model leads to a coexistence curve that almost coincides with that of the AO model and the Ising critical behavior of static quantities is reproduced. Then the …