Now showing items 1-20 of 779

• #### Goal-oriented adaptivity using unconventional error representations for the multi-dimensional Helmholtz equation ﻿

(International Journal for Numerical Methods in Engineering, 2017-06-27)
In goal‐oriented adaptivity, the error in the quantity of interest is represented using the error functions of the direct and adjoint problems. This error representation is subsequently bounded above by element‐wise error ...
• #### Refined Isogeometric Analysis for a Preconditioned Conjugate Gradient Solver ﻿

(Computer Methods in Applied Mechanics and Engineering, 2018-06-15)
Starting from a highly continuous Isogeometric Analysis (IGA) discretization, refined Isogeometric Analysis (rIGA) introduces $C^0$ hyperplanes that act as separators for the direct LU factorization solver. As a result, ...
• #### On numerical quadrature for $C^1$ quadratic Powell-Sabin 6-split macro-triangles ﻿

(Journal of Computational and Applied Mathematics, 2018-08-01)
The quadrature rule of Hammer and Stroud [16] for cubic polynomials has been shown to be exact for a larger space of functions, namely the $C^1$ cubic Clough-Tocher spline space over a macro-triangle if and only if the ...
• #### Defects in Nematic Shells: a Gamma-convergence discrete-to-continuum approach ﻿

(Archive for Rational Mechanics and Analysis, 2018-07)
In this paper we rigorously investigate the emergence of defects on Nematic Shells with a genus different from one. This phenomenon is related to a non-trivial interplay between the topology of the shell and the alignment ...
• #### Hölder equivalence of complex analytic curve singularities ﻿

(Bulletin of the London Mathematical Society, 2018-08-06)
We prove that if two germs of irreducible complex analytic curves at $0\in\mathbb{C}^2$ have different sequence of characteristic exponents, then there exists $0<\alpha<1$ such that those germs are not $\alpha$-H\"older ...
• #### Spacecraft Trajectory Optimization: A review of Models, Objectives, Approaches and Solutions ﻿

(Progress in Aerospace Sciences, 2018)
This article is a survey paper on solving spacecraft trajectory optimization problems. The solving process is decomposed into four key steps of mathematical modeling of the problem, defining the objective functions, ...
• #### Multi-stage splitting integrators for sampling with modified Hamiltonian Monte Carlo methods ﻿

(Journal of Computational Physics, 2018-07-17)
Modified Hamiltonian Monte Carlo (MHMC) methods combine the ideas behind two popular sampling approaches: Hamiltonian Monte Carlo (HMC) and importance sampling. As in the HMC case, the bulk of the computational cost of ...
• #### On the regularity of solutions to the k-generalized korteweg-de vries equation ﻿

(Proceedings of the American Mathematical Society, 2018-07)
This work is concerned with special regularity properties of solutions to the k-generalized Korteweg-de Vries equation. In [Comm. Partial Differential Equations 40 (2015), 1336–1364] it was established that if the initial ...
• #### Variational multiscale stabilization for compressible flow ﻿

(Computer Methods in Applied Mechanics and Engineering, 2018)
This paper presents a variational multiscale stabilization for the finite element numerical solution of the Euler and Navier-Stokes equations of compressible flow. All the components of the dual operator are considered in ...
• #### Absence of eigenvalues of two-dimensional magnetic Schroedinger operators ﻿

(2018-01-01)
By developing the method of multipliers, we establish sufficient conditions on the electric potential and magnetic field which guarantee that the corresponding two-dimensional Schroedinger operator possesses no point ...
• #### Asymptotics in Fourier space of self-similar solutions to the modified Korteweg-de Vries equation ﻿

(2018-07-06)
We give the asymptotics of the Fourier transform of self-similar solutions to the modified Korteweg-de Vries equation, through a fixed point argument in weighted $W^{1,\infty}$ around a carefully chosen, two term ansatz. ...
• #### On the improvement of the Hardy inequality due to singular magnetic fields ﻿

(2018-07-12)
We establish magnetic improvements upon the classical Hardy inequality for two specific choices of singular magnetic fields. First, we consider the Aharonov-Bohm field in all dimensions and establish a sharp Hardy-type ...
• #### A computational model integrating brain electrophysiology and metabolism highlights the key role of extracellular potassium and oxygen ﻿

(Journal of Theoretical Biology, 2018-02-26)
The human brain is a small organ which uses a disproportional amount of the total metabolic energy pro- duction in the body. While it is well understood that the most significant energy sink is the maintenance of the ...
• #### Transitions between bursting modes in the integrated oscillator model for pancreatic β-cells ﻿

(Journal of Theoretical Biology, 2018-06-20)
Insulin-secreting $\beta$-cells of pancreatic islets of Langerhans produce bursts of electrical impulses, resulting in intracellular Ca$^{2+}$ oscillations and pulsatile insulin secretion. The mechanism for this bursting ...
• #### Regularity of fractional maximal functions through Fourier multipliers ﻿

(2018)
We prove endpoint bounds for derivatives of fractional maximal functions with either smooth convolution kernel or lacunary set of radii in dimensions $n \geq 2$. We also show that the spherical fractional maximal function ...
• #### Variable coefficient Wolff-type inequalities and sharp local smoothing estimates for wave equations on manifolds ﻿

(2018)
The sharp Wolff-type decoupling estimates of Bourgain--Demeter are extended to the variable coefficient setting. These results are applied to obtain new sharp local smoothing estimates for wave equations on compact Riemannian ...
• #### Sparse bounds for pseudodifferential operators ﻿

(Journal d'Analyse Mathématique, 2018)
We prove sparse bounds for pseudodifferential operators associated to H\"ormander symbol classes. Our sparse bounds are sharp up to the endpoint and rely on a single scale analysis. As a consequence, we deduce a range of ...
• #### Spectral stability of Schrödinger operators with subordinated complex potentials ﻿

(Journal of Spectral Theory, 2018-06-28)
We prove that the spectrum of Schroedinger operators in three dimensions is purely continuous and coincides with the non-negative semiaxis for all potentials satisfying a form-subordinate smallness condition. By developing ...
• #### On the Relationship between the One-Corner Problem and the $M-$Corner Problem for the Vortex Filament Equation ﻿

(Journal of Nonlinear Science, 2018-06-28)
In this paper, we give evidence that the evolution of the vortex filament equation (VFE) for a regular M-corner polygon as initial datum can be explained at infinitesimal times as the superposition of M one-corner initial ...
• #### On intermediate-scale open-sea experiments on floating offshore structures: Feasibility and application on a spar support for offshore wind turbines ﻿

(Marine Structures, 2018-06-28)
Experimental investigation of floating structures represents the most direct way for achieving their dynamic identification and it is particularly valuable for relatively new concepts, such as floating supports for offshore ...