Now showing items 235-254 of 1021

• #### Determination of convection terms and quasi-linearities appearing in diffusion equations ﻿

(2018-12)
We consider the highly nonlinear and ill posed inverse problem of determining some general expression appearing in the a diffusion equation from measurements of solutions on the lateral boundary. We consider both linear ...
• #### Diagonalizing quadratic bosonic operators by non-autonomous flow equations volker bach ﻿

(Memoirs of the American Mathematical Society, 2016-01-01)
We study a non-autonomous, non-linear evolution equation on the space of operators on a complex Hilbert space. We specify assumptions that ensure the global existence of its solutions and allow us to derive its asymptotics ...
• #### Dicentric dose estimates for patients undergoing radiotherapy in the RTGene study to assess blood dosimetric models and the new Bayesian method for gradient exposure ﻿

(2018-06-01)
The RTGene study was focused on the development and validation of new transcriptional biomarkers for prediction of individual radiotherapy (RT) patient responses to ionising radiation (IR). In parallel, for validation ...
• #### Dimension reduction for the micromagnetic energy functional on curved thin films ﻿

(2016-12-14)
Micromagnetic con gurations of the vortex and onion type have beenwidely studied in the context of planar structures. Recently a signi cant interest to micromagnetic curved thin lms has appeared. In particular, thin ...
• #### Dimensionally adaptive hp-finite element simulation and inversion of 2D magnetotelluric measurements ﻿

(Journal of Computational Science, 2016-09-01)
Magnetotelluric (MT) problems often contain different subdomains where the conductivity of the media depends upon one, two, or three spatial variables. Traditionally, when a MT problem incorporates a three-dimensional (3D) ...
• #### A direct algorithm in some free boundary problems ﻿

(Journal of Numerical Mathematics, 2016-06-28)
In this paper we propose a new algorithm for the well known elliptic obstacle problem and for parabolic variational inequalities like one and two phase Stefan problem and of obstacle type. Our approach enters the category ...
• #### Direct FEM large scale computation of turbulent multiphase flow in urban water systems and marine energy ﻿

(Proceesings of ECCOMAS Congress 2016 VII European Congress on Computational Methods in Applied Sciences and Engineering, 2016-11-30)
High-Reynolds number turbulent incompressible multiphase flow represents a large class of engineering problems of key relevance to society. Here we describe our work on modeling two such problems: 1. The Consorcio de Aguas ...
• #### Direct finite element simulation of turbulent flow for marine based renewable energy ﻿

(Companion paper to F. Wendt, et. al. International energy agency ocean energy systems task 10 wave energy converter modeling verification and validation. In 12th European Wave and Tidal Energy Conference, 2017., 2017)
In this article we present a computational framework for simulation of turbulent flow in marine based renewable energy applications. In particular, we focus on floating structures and rotating turbines. This work is an ...
• #### Direct solvers performance on h-adapted grids ﻿

(Computers and Mathematics with Applications, 2015-12-31)
We analyse the performance of direct solvers when applied to a system of linear equations arising from an $h$-adapted, $C^0$ finite element space. Theoretical estimates are derived for typical $h$-refinement patterns arising ...
• #### Discontinuous high-order finite-volume/finite-element method for inviscid compressible flows ﻿

(53rd AIAA Aerospace Sciences Meeting (2015), 2015-12-31)
The discontinuous, hybrid control-volume/finite-element method merges the desirable conservative properties and intuitive physical formulation of the finite-volume technique, with the capability of local arbitrary high-order ...
• #### Discrete maximum principles for nonlinear parabolic PDE systems ﻿

(IMA Journal of Numerical Analysis, 2012-12-31)
Discrete maximum principles (DMPs) are established for finite element approximations of systems of nonlinear parabolic partial differential equations with mixed boundary and interface conditions. The results are based on ...
• #### Discrete nonnegativity for nonlinear cooperative parabolic PDE systems with non-monotone coupling ﻿

(Mathematics and Computers in Simulation, 2013-12-31)
Discrete nonnegativity principles are established for finite element approximations of nonlinear parabolic PDE systems with mixed boundary conditions. Previous results of the authors are extended such that diagonal dominance ...
• #### Discreteness of transmission eigenvalues for higher-order main terms and perturbations ﻿

(SIAM Journal on Mathematical Analysis, 2016-07-01)
In this paper we extend Sylvester's approach via upper triangular compact operators to establish the discreteness of transmission eigenvalues for higher-order main terms and higher-order perturbations. The coefficients of ...
• #### The Discreteness-driven Relaxation of Collisionless Gravitating Systems: Entropy Evolution in External Potentials, N-dependence, and the Role of Chaos ﻿

(The Astrophysical Journal, 2019-01-10)
We investigate the old problem of the fast relaxation of collisionless N-body systems that are collapsing or perturbed, emphasizing the importance of (noncollisional) discreteness effects. We integrate orbit ensembles in ...
• #### Discretizations of the spectral fractional Laplacian on general domains with Dirichlet, Neumann, and Robin boundary conditions ﻿

(2017-04-28)
In this work, we propose novel discretisations of the spectral fractional Laplacian on bounded domains based on the integral formulation of the operator via the heat-semigroup formalism. Specifically, we combine suitable ...
• #### Dispersion for 1-d Schrödinger and wave equations with bv coefficients ﻿

(Annales de l'Institut Henri Poincare. Annales: Analyse Non Lineaire/Nonlinear Analysis, 2016-01-01)
In this paper we analyze the dispersion for one dimensional wave and Schrödinger equations with BV coefficients. In the case of the wave equation we give a complete answer in terms of the variation of the logarithm of the ...
• #### Dispersion for the Schrödinger equation on networks ﻿

(Journal of Mathematical Physics, 2011-12-31)
In this paper, we consider the Schrödinger equation on a network formed by a tree with the last generation of edges formed by infinite strips. We give an explicit description of the solution of the linear Schrödinger ...
• #### Dispersion-minimizing quadrature rules for $C^1$ quadratic isogeometric analysis ﻿

(Computer Methods in Applied Mechanics and Engineering, 2017-09-20)
We develop quadrature rules for the isogeometric analysis of wave propagation and structural vibrations that minimize the discrete dispersion error of the approximation. The rules are optimal in the sense that they only ...
• #### Dispersive effects of weakly compressible and fast rotating inviscid fluids ﻿

(Discrete and Continuous Dynamical Systems - Series A, 2017-08)
We consider a system describing the motion of an isentropic, inviscid, weakly compressible, fast rotating fluid in the whole space $\mathbb{R}^3$, with initial data belonging to $H^s \left( \mathbb{R}^3 \right), s>5/2$. ...
• #### Dispersive Properties for Discrete Schrödinger Equations ﻿

(Journal of Fourier Analysis and Applications, 2011-12-31)
In this paper we prove dispersive estimates for the system formed by two coupled discrete Schrödinger equations. We obtain estimates for the resolvent of the discrete operator and prove that it satisfies the limiting ...