Search results for "modeling"
showing 10 items of 4489 documents
Analytical and Numerical Investigation of 3D Multilayer Detachment Folding
2013
Multilayer detachment folding, in which a sequence of sedimentary layers is compressed above a weaker salt layer, is a common mode of deformation in thin-skinned fold-and-thrust belts. Here, we investigate the dynamics of multilayer detachment folding with three different viscosities: lower detachment or salt layer, overlying weak layers and competent layers. A semi-analytical solution, based on thick plate analysis of multilayer systems, is used to create mechanical phase diagrams of folding dominant wavelength and growth rate as a function of material parameters. The validity of the phase diagrams is tested and confirmed beyond the nucleation stages of folding by performing several 2D and…
Interface and Surface Properties of Short Polymers in Solution: Monte Carlo Simulations and Self-Consistent Field Theory
2000
We investigate the structure and thermodynamics of inhomogeneous polymer solutions in the framework of a coarse-grained off-lattice model. Properties of the liquidvapor interface and the packing of...
An approach to evaluation of sheet bending force under successive multiaxial stress condition
2009
A new bending under tension test is presented in this paper. This method tries to evaluate bending forces in sheet under successive multiaxial stress condition. This test is carried out in only one step with a pinned cylinder over a material that has been previously deformed to pure shear condition. Due to that, the bending process is made under higher back tension forces than the ones involved in the common methods previously studied in the literature. This entails high pressure values in the sheet-bending tool contact that affects the corresponding friction process. Material is strongly strengthened as a consequence of the deformation practiced in it, and as a result of that, bending forc…
Monte Carlo simulations of polymer dynamics: Recent advances
1997
A brief review is given of applications of Monte Carlo simulations to study the dynamical properties of coarse-grained models of polymer melts, emphasizing the crossover from the Rouse model toward reptation, and the glass transition. The extent to which Monte Carlo algorithms can mimic the actual chain dynamics is critically examined, and the need for the use of coarse-grained rather than fully atomistic models for such simulations is explained. It is shown that various lattice and continuum models yield qualitatively similar results, and the behavior agrees with the findings of corresponding molecular dynamics simulations and experiments, where available. It is argued that these simulatio…
Periodic orbits of single neuron models with internal decay rate 0 < β ≤ 1
2013
In this paper we consider a discrete dynamical system x n+1=βx n – g(x n ), n=0,1,..., arising as a discrete-time network of a single neuron, where 0 < β ≤ 1 is an internal decay rate, g is a signal function. A great deal of work has been done when the signal function is a sigmoid function. However, a signal function of McCulloch-Pitts nonlinearity described with a piecewise constant function is also useful in the modelling of neural networks. We investigate a more complicated step signal function (function that is similar to the sigmoid function) and we will prove some results about the periodicity of solutions of the considered difference equation. These results show the complexity of …
Power-law hereditariness of hierarchical fractal bones
2013
SUMMARY In this paper, the authors introduce a hierarchic fractal model to describe bone hereditariness. Indeed, experimental data of stress relaxation or creep functions obtained by compressive/tensile tests have been proved to be fit by power law with real exponent 0 ⩽ β ⩽1. The rheological behavior of the material has therefore been obtained, using the Boltzmann–Volterra superposition principle, in terms of real order integrals and derivatives (fractional-order calculus). It is shown that the power laws describing creep/relaxation of bone tissue may be obtained by introducing a fractal description of bone cross-section, and the Hausdorff dimension of the fractal geometry is then related …
A theoretical approach of the propagation through geometrical constraints in cardiac tissue
2007
International audience; The behaviour of impulse propagation in the presence of non-excitable scars and boundaries is a complex phenomenon and induces pathological consequences in cardiac tissue. In this article, a geometrical con¯guration is considered so that cardiac waves propagate through a thin strand, which is connected to a large mass of cells. At this interface, waves can slow down or even be blocked depending on the width of the strand. We present an analytical approach leading to determine the blockade condition, by introducing planar travelling wavefront and circular stationary wave. Eventually, the in°uence of the tissue geometry is examined on the impulse propagation velocity.
Modeling of interactions between xenobiotics and cytochrome P450 (CYP) enzymes
2015
The adverse effects to humans and environment of only few chemicals are well known. Absorption, distribution, metabolism, and excretion (ADME) are the steps of pharmaco/toxicokinetics that determine the internal dose of chemicals to which the organism is exposed. Of all the xenobiotic-metabolizing enzymes, the cytochrome P450 (CYP) enzymes are the most important due to their abundance and versatility. Reactions catalyzed by CYPs usually turn xenobiotics to harmless and excretable metabolites, but sometimes an innocuous xenobiotic is transformed into a toxic metabolite. Data on ADME and toxicity properties of compounds are increasingly generated using in vitro and modeling (in silico) tools.…
Searching for exceptional points and inspecting non-contractivity of trace distance in (anti-) PT -symmetric systems
2022
Non-Hermitian systems with parity-time ($\mathcal{PT}$) symmetry and anti-$\mathcal{PT}$ symmetry give rise to exceptional points (EPs) with intriguing properties related to, e.g., chiral transport and enhanced sensitivity, due to the coalescence of eigenvectors. In this paper, we propose a powerful and easily computable tool, based on the Hilbert-Schmidt speed (HSS), which does not require the diagonalization of the evolved density matrix, to detect exactly the EPs and hence the critical behavior of the (anti-)$\mathcal{PT}\!-$symmetric systems, especially high-dimensional ones. Our theoretical predictions, made without the need for modification of the Hilbert space, which is performed by …
Diagrammatic approach to quantum search
2014
We introduce a simple diagrammatic approach for estimating how a randomly walking quantum particle searches on a graph in continuous-time, which involves sketching small weighted graphs with self-loops and considering degenerate perturbation theory's effects on them. Using this method, we give the first example of degenerate perturbation theory solving search on a graph whose evolution occurs in a subspace whose dimension grows with $N$.