3D Helmholtz resonator with two close point-like windows: Regularisation for Dirichlet case

2021 ◽  
pp. 2150153
Author(s):  
Anna G. Belolipetskaya ◽  
Anton A. Boitsev ◽  
Silvestro Fassari ◽  
Igor Y. Popov
Keyword(s):  
Explicit Form ◽  
Helmholtz Resonator ◽  
Dirichlet Condition ◽  
Model Solution ◽  
Proper Choice ◽  
Pontryagin Space ◽  
Close Point ◽  
Model Parameter ◽  
Window Width ◽  
Symmetric Operators

In this paper, a model of 3D Helmholtz resonator with two close point-like windows is considered. The Dirichlet condition is assumed at the boundary. The model is based on the theory of self-adjoint extensions of symmetric operators in Pontryagin space. The model is explicitly solvable and allows one to obtain the equation for resonances (quasi-eigenvalues) in an explicit form. A proper choice of the model parameter leads to the coincidence of the model solution with the main term of the asymptotics (in the window width) of the realistic solution, corresponding to small windows. A regularization is suggested to obtain a realistic limiting result for two merging windows.

scholarly journals Dissipative eigenvalue problems for a Sturm–Liouville operator with a singular potential

2000 ◽  
Vol 130 (6) ◽  
pp. 1237-1257 ◽  
Author(s):  
Bernhard Bodenstorfer ◽  
Aad Dijksma ◽  
Heinz Langer
Keyword(s):  
Liouville Operator ◽  
Eigenvalue Problems ◽  
Dirichlet Condition ◽  
Continuous Functions ◽  
Dirichlet Boundary Conditions ◽  
Interface Condition ◽  
Associated Functions ◽  
Sturm Liouville ◽  
Bari Basis ◽  
Symmetric Operators

In this paper we consider the Sturm–Liouville operator d2/dx2 − 1/x on the interval [a, b], a < 0 < b, with Dirichlet boundary conditions at a and b, for which x = 0 is a singular point. In the two components L2(a, 0) and L2(0, b) of the space L2(a, b) = L2(a, 0) ⊕ L2(0, b) we define minimal symmetric operators and describe all the maximal dissipative and self-adjoint extensions of their orthogonal sum in L2(a, b) by interface conditions at x = 0. We prove that the maximal dissipative extensions whose domain contains only continuous functions f are characterized by the interface condition limx→0+(f′(x)−f′(−x)) = γf(0) with γ∈C+∪R or by the Dirichlet condition f(0+) = f(0−) = 0. We also show that the corresponding operators can be obtained by norm resolvent approximation from operators where the potential 1/x is replaced by a continuous function, and that their eigen and associated functions can be chosen to form a Bari basis in L2(a, b).

Quantification of Dextrose in Model Solution by H MR Spectroscopy at 1.5T

2002 ◽  
Vol 46 (1) ◽  
pp. 1
Author(s):  
Kyung Hee Lee ◽  
Jung Hee Lee ◽  
Soon Gu Cho ◽  
Yong Seong Kim ◽  
Hyung Jin Kim ◽  
...  
Keyword(s):  
Mr Spectroscopy ◽  
Model Solution

On a technique for deriving explicit transfer matrices of orthotropic layers

2015 ◽  
Vol 37 (4) ◽  
pp. 303-315 ◽  
Author(s):  
Pham Chi Vinh ◽  
Nguyen Thi Khanh Linh ◽  
Vu Thi Ngoc Anh
Keyword(s):  
Wave Propagation ◽  
Explicit Form ◽  
Half Space ◽  
Transfer Matrix ◽  
Rayleigh Waves ◽  
Secular Equation ◽  
Transfer Matrices ◽  
Orthotropic Layer ◽  
Wave Propagation Problem ◽  
Arbitrary Thickness

This paper presents  a technique by which the transfer matrix in explicit form of an orthotropic layer can be easily obtained. This transfer matrix is applicable for both the wave propagation problem and the reflection/transmission problem. The obtained transfer matrix is then employed to derive the explicit secular equation of Rayleigh waves propagating in an orthotropic half-space coated by an orthotropic layer of arbitrary thickness.

ENDOGENOUS GROWTH MODEL WITH HUMAN CAPITAL ON THE CIRCLE

2020 ◽  
pp. 4-9
Author(s):  
А.В. Королев
Keyword(s):  
Human Capital ◽  
Spatial Structure ◽  
Endogenous Growth ◽  
Explicit Form ◽  
Growth Model ◽  
Main Attention ◽  
Endogenous Growth Model ◽  
Central Plan ◽  
Special Case

В статье рассматривается модель эндогенного роста с человеческим капи-талом на простой пространственной структуре (окружности). Особое вни-мание уделено специальному случаю - комбинации параметров, при кото-рой удаётся получить решение задачи центрального планировщика на окружности в явном виде, что другим авторам не удавалось. In this article the endogenous growth model with human capital on the simple spatial structure (the circle) is considered. We pay main attention to a special case of a combination of parameters for which we were able to solve the central plan-ner problem on the circle in an explicit form, which other authors did not suc-ceed to do.

On compressions of self-adjoint extensions of a symmetric linear relation with unequal deficiency indices

2019 ◽  
Vol 16 (4) ◽  
pp. 567-587
Author(s):  
Vadim Mogilevskii
Keyword(s):  
Hilbert Space ◽  
Boundary Conditions ◽  
Linear Relation ◽  
Deficiency Indices ◽  
Space Extension ◽  
Limit Value ◽  
Abstract Boundary ◽  
Symmetric Linear Relation ◽  
Symmetric Operators

Let $A$ be a symmetric linear relation in the Hilbert space $\gH$ with unequal deficiency indices $n_-A <n_+(A)$. A self-adjoint linear relation $\wt A\supset A$ in some Hilbert space $\wt\gH\supset \gH$ is called an (exit space) extension of $A$. We study the compressions $C (\wt A)=P_\gH\wt A\up\gH$ of extensions $\wt A=\wt A^*$. Our main result is a description of compressions $C (\wt A)$ by means of abstract boundary conditions, which are given in terms of a limit value of the Nevanlinna parameter $\tau(\l)$ from the Krein formula for generalized resolvents. We describe also all extensions $\wt A=\wt A^*$ of $A$ with the maximal symmetric compression $C (\wt A)$ and all extensions $\wt A=\wt A^*$ of the second kind in the sense of M.A. Naimark. These results generalize the recent results by A. Dijksma, H. Langer and the author obtained for symmetric operators $A$ with equal deficiency indices $n_+(A)=n_-(A)$.

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