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We show that non-linear optical structures involving a balanced gain-loss profile, can act as unidirectional optical valves. This is made possible by exploiting the interplay between the fundamental symmetries of parity (P) and time (T),…

We consider adaptive control problem in presence of nonlinear parametrization of uncertainties in the model. It is shown that despite traditional approaches require for domination in the control loop during adaptation, it is not often…

Optimization and Control · Mathematics 2007-05-23 Ivan Tyukin , Cees van Leeuwen

We show a result on propagation of the anisotropic Gabor wave front set for linear operators with a tempered distribution Schwartz kernel. The anisotropic Gabor wave front set is parametrized by a positive parameter relating the space and…

Analysis of PDEs · Mathematics 2024-11-20 Patrik Wahlberg

We introduce a Gaussian process-based model for handling of non-stationarity. The warping is achieved non-parametrically, through imposing a prior on the relative change of distance between subsequent observation inputs. The model allows…

Machine Learning · Statistics 2019-12-06 David Tolpin

Gabor transform is one of the performed tools for time-frequency signal analysis. The principal aim of this paper is to generalize the Gabor Fourier transform to the quaternion linear canonical transform. Actually, this transform gives us…

Classical Analysis and ODEs · Mathematics 2019-06-07 Mohammed El Kassimi , Said Fahlaoui

We study existence, stability, and dynamics of linear and nonlinear stationary modes propagating in radially symmetric multi-core waveguides with balanced gain and loss. We demonstrate that, in general, the system can be reduced to an…

We find sufficient conditions on a compactly supported function $g$, $\supp g = [a,b]$ which guarantee that the Gabor system $$\mathcal{G}(g;\alpha,\beta)=\{e^{2\pi i \beta m x}g(x-\alpha n)\}_{m,n\in\mathbb{Z}}$$ is a frame for all $\alpha…

Functional Analysis · Mathematics 2025-12-05 Yurii Belov , Aleksei Kulikov

There is a review of what is known about global non-inertial frames in special and general relativity.

General Relativity and Quantum Cosmology · Physics 2013-10-17 Luca Lusanna

Sparse graphs and their associated matroids play an important role in rigidity theory, where they capture the combinatorics of generically rigid structures. We define a new family called {\bf graded sparse graphs}, arising from generically…

Combinatorics · Mathematics 2011-11-10 Audrey Lee , Ileana Streinu , Louis Theran

This paper deals with the state estimation of non-linear and non-Gaussian systems with an emphasis on the numerical solution to the Bayesian recursive relations. In particular, this paper builds upon the Lagrangian grid-based filter (GbF)…

Signal Processing · Electrical Eng. & Systems 2026-02-20 Jindřich Duník , Jan Krejčí , Jakub Matoušek , Marek Brandner , Yeongkwon Choe

We derive an integral expression for the plane-wave expansion of the time-varying (nonstationary) random field inside a mode-stirred reverberation chamber. It is shown that this expansion is a so-called oscillatory process, whose kernel can…

Optics · Physics 2015-05-18 Luk R. Arnaut

We establish the restricted isometry property for finite dimensional Gabor systems, that is, for families of time--frequency shifts of a randomly chosen window function. We show that the $s$-th order restricted isometry constant of the…

Information Theory · Computer Science 2014-04-29 Götz E. Pfander , Holger Rauhut , Joel A. Tropp

This article introduces a nonparametric approach to spectral analysis of a high-dimensional multivariate nonstationary time series. The procedure is based on a novel frequency-domain factor model that provides a flexible yet parsimonious…

Methodology · Statistics 2019-10-29 Zeda Li , Ori Rosen , Fabio Ferrarelli , Robert T. Krafty

Metaplectic Wigner distributions generalize the most popular time-frequency representations, such as the short-time Fourier transform (STFT) and $\tau$-Wigner distributions, using metaplectic operators. However, in order for a metaplectic…

Analysis of PDEs · Mathematics 2024-03-27 Elena Cordero , Gianluca Giacchi

One of the most remarkable predictions to emerge out of the exact infinite-dimensional solution of the glass problem is the Gardner transition. Although this transition was first theoretically proposed a generation ago for certain…

Statistical Mechanics · Physics 2019-08-30 Ludovic Berthier , Giulio Biroli , Patrick Charbonneau , Eric I. Corwin , Silvio Franz , Francesco Zamponi

We propose a new scenario for glassy dynamics in frustrated systems with no quenched-in randomness, based on jamming of extended dynamical structures near a critical point. This route to a glassy state is demonstrated in a lattice model of…

Statistical Mechanics · Physics 2007-05-23 Dibyendu Das , Jane' Kondev , Bulbul Chakraborty

In the following, we discuss nonlinear simulations of nonlinear dynamical systems, which are applied in technical and biological models. We deal with different ideas to overcome the treatment of the nonlinearities and discuss a novel…

Numerical Analysis · Mathematics 2014-12-01 Juergen Geiser , Vahid Yaghoubi

This paper shows how the theory of nonlinear adaptive observers can be effectively used in the design of internal models for nonlinear output regulation. The theory substantially enhances the existing results in the context of {\em…

Optimization and Control · Mathematics 2007-05-23 Francesco Delli Priscoli , Lorenzo Marconi , Alberto Isidori

Locally adaptive differential frames (gauge frames) are a well-known effective tool in image analysis, used in differential invariants and PDE-flows. However, at complex structures such as crossings or junctions, these frames are not…

Group Theory · Mathematics 2017-01-13 R. Duits , M. H. J. Janssen , J. Hannink , G. R. Sanguinetti

A noncommutative algebra corresponding to the classical catenoid is introduced together with a differential calculus of derivations. We prove that there exists a unique metric and torsion-free connection that is compatible with the complex…

Quantum Algebra · Mathematics 2018-02-14 Joakim Arnlind , Christoffer Holm