Search results for "granularity"
showing 10 items of 40 documents
Fine Grained Tensor Network Methods.
2020
We develop a strategy for tensor network algorithms that allows to deal very efficiently with lattices of high connectivity. The basic idea is to fine-grain the physical degrees of freedom, i.e., decompose them into more fundamental units which, after a suitable coarse-graining, provide the original ones. Thanks to this procedure, the original lattice with high connectivity is transformed by an isometry into a simpler structure, which is easier to simulate via usual tensor network methods. In particular this enables the use of standard schemes to contract infinite 2d tensor networks - such as Corner Transfer Matrix Renormalization schemes - which are more involved on complex lattice structu…
Intergrain Effects in the AC Susceptibility of Polycrystalline LaFeAsO_{0.94}F_{0.06}
2010
The AC susceptibility, chi, at zero DC magnetic field of a polycrystalline sample of LaFeAsO_{0.94}F_{0.06} (Tc ≈ 24 K) has been investigated as a function of the temperature, the amplitude of the AC magnetic field (in the range Hac = 0.003 Oe - 4 Oe) and the frequency (in the range f = 10 kHz - 100 kHz). The chi(T) curve exhibits the typical two-step transition arising from the combined response of superconducting grains and intergranular weak-coupled medium. The intergranular part of chi strongly depends on both the amplitude and the frequency of the AC driving field, from few Kelvin below Tc down to T = 4.2 K. Our results show that, in the investigated sample, the intergrain critical cur…
Coarse-graining dipolar interactions in simple fluids and polymer solutions: Monte Carlo studies of the phase behavior
2009
In this paper we investigate the phase diagram of pure dipolar substances and their mixtures with short alkanes, using grand canonical Monte Carlo simulations of simplified coarse-grained models. Recently, an efficient coarse-grained model for simple quadrupolar molecules, based on a Lennard-Jones (LJ) interaction plus a spherically averaged quadrupolar potential, has been shown to be successful in predicting single-component and mixture phase diagrams. Motivated by these results, we investigate the phase diagrams of simple dipolar molecules (and their mixtures with alkanes) using a spherically averaged potential. First, we test the model on pure components. A generalized (state-dependent) …
A Tsetlin Machine with Multigranular Clauses
2019
The recently introduced Tsetlin Machine (TM) has provided competitive pattern recognition accuracy in several benchmarks, however, requires a 3-dimensional hyperparameter search. In this paper, we introduce the Multigranular Tsetlin Machine (MTM). The MTM eliminates the specificity hyperparameter, used by the TM to control the granularity of the conjunctive clauses that it produces for recognizing patterns. Instead of using a fixed global specificity, we encode varying specificity as part of the clauses, rendering the clauses multigranular. This makes it easier to configure the TM because the dimensionality of the hyperparameter search space is reduced to only two dimensions. Indeed, it tur…
Bank-specific shocks and aggregate leverage: Empirical evidence from a panel of developed countries
2020
International audience; This paper investigates the link between shocks in the banking sector and aggregate leverage measured by the credit-to-GDP gap. Using a balanced panel of 15 countries for the period 1989–2016, we exploit the approach due to Gabaix (2011) and consider banking granular shocks as an indicator of banking distress. Using methods that account for potential endogeneity, we find that banking shocks Granger-cause aggregate leverage. In particular, banking shocks tend to increase the level of leverage and cause departures of the credit-to-GDP ratio from its long-term trend.
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…
Force probe simulations using an adaptive resolution scheme
2021
Molecular simulations of the forced unfolding and refolding of biomolecules or molecular complexes allow to gain important kinetic, structural and thermodynamic information about the folding process and the underlying energy landscape. In force probe molecular dynamics (FPMD) simulations, one pulls one end of the molecule with a constant velocity in order to induce the relevant conformational transitions. Since the extended configuration of the system has to fit into the simulation box together with the solvent such simulations are very time consuming. Here, we apply a hybrid scheme in which the solute is treated with atomistic resolution and the solvent molecules far away from the solute a…
Influence of the parameters molecular structure and granularity on the compactibility of a powder
1995
Drug Dev. Ind. Pharm. ISI Document Delivery No.: RP128 Times Cited: 3 Cited Reference Count: 14 Andres, c ndiaye, a thomas, c tromelin, a chaillot, b pourcelot, y; International audience; The aim of this study was to determine whether it is possible to obtain better characterization of materials in order to find out if these one are suitable in Quality Assurance for direct tableting. We tried to show that a methodological approach combining chemical, physical and technological aspects could control the direct compression process. We chose orthoboric acid as a study model for the direct compression. From a chemical point of view, our findings show only one crystalline molecular structure (RX…
Development of Structured Scintillator Tiles for High-Granularity Calorimeters
2020
Calorimeters with a fine 3-D segmentation are considered to be a very promising technology for future high-energy physics experiments, since they provide in combination with particle flow algorithms excellent jet energy resolution and particle identification capabilities. Depending on the size, millions of individual channels consisting of a photosensor coupled to a scintillator tile have to be assembled. The usage of structured plastic scintillators with optically separated segments simplifies the mass production. We present the design, production, and performance of a 36 cm × 36 cm scintillator tile divided into 144 segments matching the geometry of the SiPM-based calorimeter frontend dev…
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.