In this paper we study the spectra of bounded self-adjoint linear operators that are related to finite Hilbert transforms and . These operators arise when one studies the interior problem of tomography. The diagonalization of has been previously obtained, but only asymptotically when . We implement a novel approach based on the method of matrix Riemann-Hilbert problems (RHP) which diagonalizes explicitly. We also find the asymptotics of the solution to a related RHP and obtain error estimates.
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http://dx.doi.org/10.1007/s13324-020-00371-6 | DOI Listing |
J Phys Condens Matter
January 2025
School of Physical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S.C. Mullick Road, Jadavpur, Kolkata, Kolkata, West Bengal, 700032, INDIA.
Periodically driven closed quantum systems are expected to eventually heat up to infinite temperature ; reaching a steady state described by a circular orthogonal ensemble (COE). However, such finite driven systems may exhibit sufficiently long prethermal regimes; their properties in these regimes are qualitatively different from that of their corresponding infinite temperature steady states. These, often experimentally relevant, prethermal regimes host a wide range of phenomena; they may exhibit dynamical localization and freezing, host Floquet scars, display signatures of Hilbert space fragmentation, and exhibit time crystalline phases.
View Article and Find Full Text PDFEntropy (Basel)
December 2024
Institute of Control & Computation Engineering, University of Zielona Góra, Licealna 9, 65-417 Zielona Góra, Poland.
Infinite-dimensional systems play an important role in the continuous-variable quantum computation model, which can compete with a more standard approach based on qubit and quantum circuit computation models. But, in many cases, the value of entropy unfortunately cannot be easily computed for states originating from an infinite-dimensional Hilbert space. Therefore, in this article, the unified quantum entropy (which extends the standard von Neumann entropy) notion is extended to the case of infinite-dimensional systems by using the Fredholm determinant theory.
View Article and Find Full Text PDFAppl Math Mod Chall
March 2024
Department of Mathematics University of Southern California Los Angeles CA 90089-2532, USA.
The utility of newly developed wearable biosensors for passively, non-invasively, and continuously measuring transdermal alcohol levels in the body in real time has been limited by the fact that raw transdermal alcohol data does not consistently correlate (quantitatively or temporally) with interpretable metrics of breath and blood across individuals, devices, and the environment. A novel method using a population model in the form of a random abstract hybrid system of ordinary and partial differential equations and linear quadratic tracking control in Hilbert space is developed to estimate blood or breath alcohol concentration from the biosensor-produced transdermal alcohol level signal. Using human subject data in the form of 270 drinking episodes, the method is shown to produce estimates of blood or breath alcohol concentration that are highly correlated and thus good predictors of breath analyzer measurements.
View Article and Find Full Text PDFSci Rep
November 2024
Sichuan Highway Planning, Survey, Design and Research Institute Ltd, Chengdu, China.
Vibratory rollers are generally used in the process of highway subgrade compaction. In the paper, the vibratory roller-subgrade finite element model was established to simulate the field construction by using ABAQUS. We used Hilbert-Huang Transform to analyze the compaction in the field test from the time-frequency domain.
View Article and Find Full Text PDFJ Imaging
November 2024
National Institute for Applied Sciences (INSA Rouen Normandie), Laboratoire de Mathématiques de l'INSA, LMI-UR 3226, 76000 Rouen, France.
In this paper, we propose a global modelling for vector field approximation from a given finite set of vectors (corresponding to the wind velocity field or marine currents). In the modelling, we propose using the minimization on a Hilbert space of an energy functional that includes a fidelity criterion to the data and a smoothing term. We discretize the continuous problem using a finite elements method.
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