Now showing items 339-358 of 1055

• #### Fast 2.5D Finite Element Simulations of Borehole Resistivity Measurements ﻿

(Computational Geosciences, 2018-05-29)
We develop a rapid 2.5-dimensional (2.5D) finite element method for simulation of borehole resistivity measurements in transversely isotropic (TI) media. The method combines arbitrary high-order $H^1$ - and $H$ (curl)-conforming ...
• #### Fast algorithm for smoothing parameter selection in multidimensional P-splines ﻿

(Statistics and Computing, 2015-12-31)
A new computational algorithm for estimating the smoothing parameters of a multidimensional penalized spline generalized model with anisotropic penalty is presented. This new proposal is based on the mixed model representation ...
• #### Fast estimation of multidimensional adaptive P-spline models ﻿

(2016-10-21)
A fast and stable algorithm for estimating multidimensional adaptive P-spline models is presented. We call it as Separation of Overlapping Penalties (SOP) as it is an extension of the Separation of Anisotropic Penalties ...
• #### Fast inversion of logging-while-drilling resistivity measurements acquired in multiple wells ﻿

(Geophysics, 2016-10)
This paper introduces a new method for the fast inversion of borehole resistivity measurements acquired in multiple wells using logging-while-drilling (LWD) instruments. There are two key novel contributions. First, we ...
• #### Fast One-dimensional Finite Element Approximation of Geophysical Measurements ﻿

(2018)
There exist a wide variety of geophysical prospection methods. In this work, we focus on resistivity methods. We categorize these resistivity prospection methods according to their acquisition location as (a) on the surface, ...
• #### Fast simulation of through-casing resistivity measurements using semi-analytical asymptotic models. Part 1: Accuracy study ﻿

(EAGE Workshop on High Performance Computing for Upstream 2014, 2014-12-31)
When trying to obtain a better characterization of the Earth's subsurface, it is common to use borehole through-casing resistivity measurements. It is also common for the wells to be surrounded by a metal casing to protect ...
• #### Fast smoothing parameter separation in multidimensional generalized P-splines: the SAP algorithm ﻿

(Statistics and Computing, 2014-12-31)
A new computational algorithm for estimating the smoothing parameters of a multidimensional penalized spline generalized linear model with anisotropic penalty is presented. This new proposal is based on the mixed model ...
• #### A FEniCS-HPC framework for multi-compartment Bloch-Torrey models ﻿

(Proceesings of ECCOMAS Congress 2016 VII European Congress on Computational Methods in Applied Sciences and Engineering, 2016-11-30)
In diffusion nuclear magnetic resonance (NMR) and diffusion magnetic resonance imaging (MRI), the multi-compartment Bloch-Torrey equation plays an important role in probing the diffusion characteristics from a nanometer ...
• #### FEniCS-HPC: Automated predictive high-performance finite element computing with applications in aerodynamics ﻿

(Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 2016-01-01)
Developing multiphysics finite element methods (FEM) and scalable HPC implementations can be very challenging in terms of software complexity and performance, even more so with the addition of goal-oriented adaptive mesh ...
• #### Fine structure of spectral properties for random correlation matrices: An application to financial markets ﻿

(Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 2011-12-31)
We study some properties of eigenvalue spectra of financial correlation matrices. In particular, we investigate the nature of the large eigenvalue bulks which are observed empirically, and which have often been regarded ...
• #### Finite element approximation of electromagnetic fields using nonfitting meshes for Geophysics ﻿

(SIAM Journal on Numerical Analysis, 2018-07)
We analyze the use of nonfitting meshes for simulating the propagation of electromagnetic waves inside the earth with applications to borehole logging. We avoid the use of parameter homogenization and employ standard edge ...
• #### Finite Element Simulations of Logging-While-Drilling and Extra-Deep Azimuthal Resistivity Measurements using Non-Fitting Grids ﻿

(Computational Geosciences, 2018-04-27)
We propose a discretization technique using non-fitting grids to simulate magnetic field-based resistivity logging measurements. Non-fitting grids are convenient because they are simpler to generate and handle than fitting ...
• #### Finite Element Simulations of Two-phase Flow and Floating Bodies Using FEniCS-HPC ﻿

(13th World Congress in Computational Mechanics WCCM, New York, USA, 2018-07)
We present a variational multiscale stabilized finite element method to solve the variable density incompressible Navier-Stokes equations for the simulation of two-phase flow. We introduce a level-set method based on the ...
• #### Finite time blow-up and condensation for the bosonic Nordheim equation ﻿

(Inventiones mathematicae, 2014-12-31)
The homogeneous bosonic Nordheim equation is a kinetic equation describing the dynamics of the distribution of particles in the space of moments for a homogeneous, weakly interacting, quantum gas of bosons. We show the ...
• #### Finite time blow-up for the bosonic Nordheim equation ﻿

(Inventiones mathematicae, 2015-12-31)
The homogeneous bosonic Nordheim equation is a kinetic equation describing the dynamics of the distribution of particles in the space of moments for a homogeneous, weakly interacting, quantum gas of bosons. We show the ...
• #### Finite-energy Lévy-type motion through heterogeneous ensemble of Brownian particles ﻿

(Journal of Physics A: Mathematical and Theoretical, 2019-02-01)
Complex systems are known to display anomalous diffusion, whose signature is a space/time scaling $x \sim t^\delta$ with $\delta \neq 1/2$ in the probability density function (PDF). Anomalous diffusion can emerge jointly ...
• #### Fire-spotting generated fires. Part I: The role of atmospheric stability ﻿

(Applied Mathematical Modelling, 2019-02)
This is the first part of two papers concerning fire-spotting generated fires. In this part we deal with the impact of macroscale factors, such as the atmospheric stability, and in the second part we deal with mesoscale ...
• #### Fitting second-order acyclic marked markovian arrival processes ﻿

(Proceedings of the International Conference on Dependable Systems and Networks, 2013-12-31)
Markovian Arrival Processes (MAPs) are a tractable class of point-processes useful to model correlated time series, such as those commonly found in network traces and system logs used in performance analysis and reliability ...
• #### Fitting the data from embryo implantation prediction: Learning from label proportions ﻿

(Statistical Methods in Medical Research, 2016-01-01)
Machine learning techniques have been previously used to assist clinicians to select embryos for human-assisted reproduction. This work aims to show how an appropriate modeling of the problem can contribute to improve ...
• #### Flexible geostatistical modeling and risk assessment analysis of lead concentration levels of residential soil in the Coeur D'Alene River Basin ﻿

(Environmental and Ecological Statistics, 2015-12-31)
Soil heavy metals pollution is an urgent problem worldwide. Understanding the spatial distribution of pollutants is critical for environmental management and decision-making. Children and adults are still routinely exposed ...