Results 31 to 40 of about 103,519 (218)

Dirac-Krein systems on star graphs [PDF]

, 2016
We study the spectrum of a self-adjoint Dirac-Krein operator with potential on a compact star graph $\mathcal G$ with a finite number $n$ of edges. This operator is defined by a Dirac-Krein differential expression with summable matrix potentials on each ...
Adamyan, Vadym, Langer, Heinz, Tretter, Christiane, Winklmeier, Monika   +3 more
core   +2 more sources

Stability Bounds for the Generalized Kadanoff‐Baym Ansatz in the Holstein Dimer

Contributions to Plasma Physics, EarlyView.
ABSTRACT Predicting real‐time dynamics in correlated systems is demanding: exact two‐time Green's function methods are accurate but often too costly, while the Generalized Kadanoff‐Baym Ansatz (GKBA) offers time‐linear propagation at the risk of uncontrolled behavior. We examine when and why GKBA fails in a minimal yet informative setting, the Holstein
Oscar Moreno Segura, Yaroslav Pavlyukh, Riku Tuovinen   +2 more
wiley   +1 more source

On the limit spectrum of a degenerate operator in the framework of periodic homogenization or singular perturbation problems

Comptes Rendus. Mathématique, 2022
In this paper we perform the analysis of the spectrum of a degenerate operator $A_\varepsilon $ corresponding to the stationary heat equation in a $\varepsilon $-periodic composite medium having two components with high contrast diffusivity.
Sili, Ali
doaj   +1 more source

Some remarks on quasi-Hermitian operators [PDF]

, 2013
A quasi-Hermitian operator is an operator that is similar to its adjoint in some sense, via a metric operator, i.e., a strictly positive self-adjoint operator.
Antoine J.-P., Barut A. O., Camillo Trapani, Dieudonné J., Dunford N., Hoover T. B., Jean-Pierre Antoine, Mackey G. W., Reed M., Reed M., Sz.-Nagy B.   +10 more
core   +1 more source

Governing Positive Energy Districts: The Role of Legitimation and Identity Across Residential and Industrial Contexts

Environmental Policy and Governance, EarlyView.
ABSTRACT Increasing electricity demand from data centres, industrial applications, electric vehicles and domestic heating is creating pressure to develop electricity systems in many parts of the world, but especially in Western countries. In response to challenges such as grid congestion, interconnection queues and climate‐related hazards, network ...
Jussi Valta, Tuomas Vanhanen, Tuomo Joensuu, Saku Mäkinen   +3 more
wiley   +1 more source

On the product of the self-adjoint operators

International Journal of Mathematics and Mathematical Sciences, 1982
A proof is given for the fact that the product of two self-adjoint operators, one of which is also positive, is again self-adjoint if and only if the product is normal. This theorem applies, in particular, if one operator is an orthogonal projection.
Wulf Rehder
doaj   +1 more source

A Class of Singular Sturm–Liouville Problems with Discontinuity and an Eigenparameter-Dependent Boundary Condition

Mathematics, 2022
In this paper, we study a singular Sturm–Liouville problem with an eigenparameter-dependent boundary condition and transmission conditions at two interior points.
Jinming Cai, Zhaowen Zheng, Kun Li
doaj   +1 more source

A dilemma in representing observables in quantum mechanics [PDF]

, 2002
There are self-adjoint operators which determine both spectral and semispectral measures. These measures have very different commutativity and covariance properties.
Ali S T, Busch P, Busch P, Busch P, Cassinelli G, Cassinelli G, D A Dubin, Davies E B, Dubin D, Dubin D A, Galindo A, Garrison J, Holevo A S, Holevo A S, Holevo A S, J P Pellonp  , Ludwig G, M A Hennings, Mackey G, Mlak W, P Lahti, Peres A, Riesz F   +22 more
core   +3 more sources

Efficient First‐Principles Inverse Design of Nanolasers

Laser &Photonics Reviews, EarlyView.
This article introduces a first‐principles inverse‐design framework for nanolasers that directly incorporates nonlinear lasing physics. By unifying steady‐state ab‐initio laser theory (SALT) with topology optimization, it reveals how spatial hole burning, gain saturation, and cavity‐emitter coupling shape laser performance, enabling efficient discovery
Beñat Martinez de Aguirre Jokisch, Alexander Cerjan, Rasmus Ellebæk Christiansen, Jesper Mørk, Ole Sigmund, Steven G. Johnson   +5 more
wiley   +1 more source

Third Order Trace Formula

, 2012
In (J. Funct. Anal. 257, 1092-1132 (2009)), Dykema and Skripka showed the existence of higher order spectral shift functions when the unperturbed self-adjoint operator is bounded and the perturbations is Hilbert-Schmidt.
Chattopadhyay, Arup, Sinha, Kalyan B.
core   +1 more source