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Digital filters for recursively computing the discrete Fourier transform (DFT) and estimating the frequency spectrum of sampled signals are examined, with an emphasis on magnitude-response and numerical stability. In this tutorial-style…

Systems and Control · Computer Science 2015-08-26 Hugh L. Kennedy

Let $\operatorname{St}^{n}_{k}\subset\mathbb{R}^{n\times k}$ be the set of all $n\times k$ matrices whose columns are mutually orthogonal and of unit Euclidean length, and let $\mu_{n,k}$ be the surface measure corresponding to this…

Classical Analysis and ODEs · Mathematics 2021-11-18 Nikolaos Chatzikonstantinou

Based on the discrete fractional random transform (DFRNT), we present the discrete fractional random cosine and sine transforms (DFRNCT and DFRNST). We demonstrate that the DFRNCT and DFRNST can be regarded as special kinds of DFRNT and…

Mathematical Physics · Physics 2009-11-11 Zhengjun Liu , Qing Guo , Shutian Liu

Coherent control has enabled various novel phenomena in wave scattering. We introduce an effect called coherent orthogonal scattering, where the output wave becomes orthogonal to the reference output state without scatterers. This effect…

Optics · Physics 2024-08-13 Cheng Guo , Shanhui Fan

Unidirectional reflectionless propagation (or transmission) is an interesting wave phenomenon observed in many $\mathcal{PT}$-symmetric optical structures. Theoretical studies on unidirectional reflectionless transmission often use simple…

Optics · Physics 2019-11-13 Lijun Yuan , Ya Yan Lu

We propose a new set of rotationally and translationally invariant features for image or pattern recognition and classification. The new features are cubic polynomials in the pixel intensities and provide a richer representation of the…

Computer Vision and Pattern Recognition · Computer Science 2011-11-09 Risi Kondor

Scalar diffraction calculations such as the angular spectrum method (ASM) and Fresnel diffraction, are widely used in the research fields of optics, X-rays, electron beams, and ultrasonics. It is possible to accelerate the calculation using…

This preliminary report addresses the expressive power of unit resolution regarding input data encoded with partial truth assignments of propositional variables. A characterization of the functions that are computable in this way, which we…

Artificial Intelligence · Computer Science 2011-06-20 Olivier Bailleux

In this paper, a new fractional operator of variable order with the use of the monotonic increasing function is proposed in sense of Caputo type. The properties in term of the Laplace and Fourier transforms are analyzed and the results for…

Statistical Mechanics · Physics 2017-07-18 Xiao-Jun Yang , J. A. Tenreiro Machado

State-of-the-art fully intrinsic networks for non-rigid shape matching often struggle to disambiguate the symmetries of the shapes leading to unstable correspondence predictions. Meanwhile, recent advances in the functional map framework…

Computer Vision and Pattern Recognition · Computer Science 2022-04-29 Nicolas Donati , Etienne Corman , Maks Ovsjanikov

We propose a new Fourier-transform spectroscopy technique based on the rotational Doppler effect. The technique offers an application for optical vortex frequency combs, where each frequency component carries a unique amount of orbital…

Optics · Physics 2024-10-28 Santeri Larnimaa , Markku Vainio

Inverse scattering is the process of estimating the spatial distribution of the scattering potential of an object by measuring the scattered wavefields around it. In this paper, we consider reflection tomography of high contrast objects…

Signal Processing · Electrical Eng. & Systems 2020-12-17 Ajinkya Kadu , Hassan Mansour , Petros T. Boufounos

It was shown recently that the anomalous scaling of simultaneous correlation functions in turbulence is intimately related to the breaking of temporal scale invariance, which is equivalent to the appearance of infinitely many times scales…

chao-dyn · Physics 2016-08-31 David Daems , Siegfried Grossmann , Victor S. L'vov , Itamar Procaccia

We consider the scattering of time-harmonic electromagnetic waves by a penetrable thin tubular scattering object in three-dimensional free space. We establish an asymptotic representation formula for the scattered wave away from the thin…

Analysis of PDEs · Mathematics 2020-10-05 Yves Capdeboscq , Roland Griesmaier , Marvin Knöller

We give a definition of scattering matrices based on the asymptotic behaviors of generalized eigenfunctions and show that these scattering matrices are equivalent to the ones defined by wave-operator approach in long-range $N$-body…

Mathematical Physics · Physics 2018-11-20 Sohei Ashida

Real life signals are in general non--stationary and non--linear. The development of methods able to extract their hidden features in a fast and reliable way is of high importance in many research fields. In this work we tackle the problem…

Numerical Analysis · Mathematics 2018-10-26 Antonio Cicone , Haomin Zhou

We present the Evolving Graph Fourier Transform (EFT), the first invertible spectral transform that captures evolving representations on temporal graphs. We motivate our work by the inadequacy of existing methods for capturing the evolving…

Machine Learning · Computer Science 2024-04-19 Anson Bastos , Kuldeep Singh , Abhishek Nadgeri , Manish Singh , Toyotaro Suzumura

We develop a scattering theory for perturbations of powers of the Laplacian on asymptotically Euclidean manifolds. The (absolute) scattering matrix is shown to be a Fourier integral operator associated to the geodesic flow at time \pi on…

Analysis of PDEs · Mathematics 2007-05-23 T. J. Christiansen , M. S. Joshi

An integrated photonic circuit architecture to perform a modified-convolution operation based on the Discrete Fractional Fourier Transform (DFrFT) is introduced. This is accomplished by utilizing two nonuniformly-coupled waveguide lattices…

Optics · Physics 2025-02-25 Kevin Zelaya , Mohammad-Ali Miri

This paper addresses the task of anomaly diagnosis when the underlying data generation process has a complex spatio-temporal (ST) dependency. The key technical challenge is to extract actionable insights from the dependency tensor…

Machine Learning · Computer Science 2023-05-30 Jokin Labaien , Tsuyoshi Idé , Pin-Yu Chen , Ekhi Zugasti , Xabier De Carlos