Results 111 to 120 of about 180,050 (282)

An Inverse Extremal Eigenproblem for Bordered Tridiagonal Matrices Applied to an Inverse Singular Value Problem for Lefkovitch-Type Matrices

Mathematics
This paper focuses on the inverse extremal eigenvalue problem (IEEP) and a special inverse singular value problem (ISVP). First, a bordered tridiagonal matrix is constructed from the extremal eigenvalues of its leading principal submatrices and an ...
Hubert Pickmann-Soto, Susana Arela-Pérez, Cristina Manzaneda, Hans Nina   +3 more
doaj   +1 more source

An inverse eigenvalue problem for an arbitrary multiply connected bounded region in R2

International Journal of Mathematics and Mathematical Sciences, 1991
The basic problem is to determine the geometry of an arbitrary multiply connected bounded region in R2 together with the mixed boundary conditions, from the complete knowledge of the eigenvalues {λi}j=1∞ for the Laplace operator, using the asymptotic ...
E. M. E. Zayed
doaj   +1 more source

Shape Derivatives of the Eigenvalues of the De Rham Complex for Lipschitz Deformations and Variable Coefficients: Part I

Mathematical Methods in the Applied Sciences, EarlyView.
ABSTRACT We study eigenvalue problems for the de Rham complex on varying three‐dimensional domains. Our analysis includes the Helmholtz equation as well as the Maxwell system with mixed boundary conditions and non‐constant coefficients. We provide Hadamard‐type formulas for the shape derivatives under weak regularity assumptions on the domain and its ...
Pier Domenico Lamberti, Dirk Pauly, Michele Zaccaron   +2 more
wiley   +1 more source

Asymptotics for the Spectrum of the Laplacian in Thin Bars with Varying Cross Sections

Mathematical Methods in the Applied Sciences, EarlyView.
ABSTRACT We consider spectral problems for the Laplace operator in 3D rod structures with a small cross section of diameter O(ε)$$ O\left(\varepsilon \right) $$, ε$$ \varepsilon $$ being a positive parameter. The boundary conditions are Dirichlet (Neumann, respectively) on the bases of this structure, and Neumann on the lateral boundary.
Pablo Benavent‐Ocejo, Delfina Gómez, Maria‐Eugenia Pérez‐Martínez   +2 more
wiley   +1 more source

A uniqueness theorem on the inverse problem for the Dirac operator

Electronic Journal of Differential Equations, 2016
In this article, we consider an inverse problem for the Dirac operator. We show that a particular set of eigenvalues is sufficient to determine the unknown potential functions.
Yu Ping Wang, Murat Sat
doaj  

High Relative Accuracy Computations With Covariance Matrices of Order Statistics

Mathematical Methods in the Applied Sciences, EarlyView.
ABSTRACT In many statistical applications, numerical computations with covariance matrices need to be performed. The error made when performing such numerical computations increases with the condition number of the covariance matrix, which is related to the number of variables and the strength of the correlation between the variables. In a recent work,
Juan Baz, Pedro Alonso, Juan Manuel Peña, Raúl Pérez‐Fernández   +3 more
wiley   +1 more source

Linear Toroidal‐Inertial Waves on A Differentially Rotating Sphere with Application to Helioseismology: Modeling, Forward and Inverse Problems

Mathematical Methods in the Applied Sciences, EarlyView.
ABSTRACT This paper develops a mathematical framework for interpreting observations of solar inertial waves in an idealized setting. Under the assumption of purely toroidal linear waves on the sphere, the stream function of the flow satisfies a fourth‐order scalar equation.
Tram Thi Ngoc Nguyen, Damien Fournier, Laurent Gizon, Thorsten Hohage   +3 more
wiley   +1 more source

A pilot variational coupled reanalysis based on the CESAM climate model

Quarterly Journal of the Royal Meteorological Society, EarlyView.
Variational data assimilation of in‐situ and satellite ocean data and reanalysis atmospheric data into an intermediate complexity Earth system model is possible by adjusting the surface fluxes and internal model parameters. This pilot application requires nearly complete information on the atmospheric state for synchronization.
Armin Köhl, Iuliia Polkova, Guokun Lyu, Frank Lunkeit, Abhirup Banerjee, Silke Schubert, Detlef Stammer   +6 more
wiley   +1 more source

The non‐hydrostatic option of the ECMWF global weather forecast model: Improvements for kilometre‐scale modelling

Quarterly Journal of the Royal Meteorological Society, EarlyView.
This study presents improvements to the non‐hydrostatic version of the European Centre for Medium‐Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS), enabling stable global simulations at 1.4‐km resolution. A systematic comparison with the hydrostatic version at resolutions from 9 to 1.4 km shows that non‐hydrostatic effects emerge in ...
Jozef Vivoda, Inna Polichtchouk, Michail Diamantakis, Filip Váňa   +3 more
wiley   +1 more source

The solvability conditions for the inverse eigenvalue problem of normal skew J-Hamiltonian matrices. [PDF]

J Inequal Appl, 2018
Zhao J, Zhang J.
europepmc   +1 more source