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The dispersive motion of surface waves is now routinely used to remotely measure the currents close beneath the surface of oceans and other natural flows. The current manifests as wavelength-dependent Doppler shifts in the spatiotemporal…

Atmospheric and Oceanic Physics · Physics 2024-08-27 Stefan Weichert , Benjamin K. Smeltzer , Simen Å. Ellingsen

In this chapter we review methods by which near--surface ocean currents can be measured remotely using images of the water surface, as obtained by X-band radar in particular. The presence of a current changes the dispersive behavior of…

Fluid Dynamics · Physics 2022-05-12 Benjamin K. Smeltzer , Simen Å. Ellingsen

A new inversion method for determining near-surface shear currents from a measured wave spectrum is introduced. The method is straightforward to implement and starts from the existing state-of-the-art technique of assigning effective depths…

Atmospheric and Oceanic Physics · Physics 2020-02-19 Benjamin K. Smeltzer , Eirik Æsøy , Anna Ådnøy , Simen Å. Ellingsen

Doppler radars are routinely used for the remote sensing of oceanic surface currents and atmospheric wind profiles. Even though they operate at different frequencies and address different media, they follow very similar processing for the…

Atmospheric and Oceanic Physics · Physics 2021-02-02 Baptiste Domps , Julien Marmain , Charles-Antoine Guérin

We report experimental observations of two canonical surface wave patterns --- ship waves and ring waves --- skewed by sub-surface shear, thus confirming effects predicted by recent theory. Observed ring waves on a still surface with…

Fluid Dynamics · Physics 2019-08-12 Benjamin K. Smeltzer , Eirik Æsøy , Simen Å. Ellingsen

There is a bias in the inference pipeline of most diffusion models. This bias arises from a signal leak whose distribution deviates from the noise distribution, creating a discrepancy between training and inference processes. We demonstrate…

Computer Vision and Pattern Recognition · Computer Science 2023-10-25 Martin Nicolas Everaert , Athanasios Fitsios , Marco Bocchio , Sami Arpa , Sabine Süsstrunk , Radhakrishna Achanta

The spectrogram is a classical DSP tool used to view signals in both time and frequency. Unfortunately, the Heisenberg Uncertainty Principal limits our ability to use them for detecting and measuring narrowband signal modulation in wideband…

Information Theory · Computer Science 2014-01-22 Ray Maleh , Frank A. Boyle

Spectrographs nominally contain a degree of quasi-static optical aberrations resulting from the quality of manufactured component surfaces, imperfect alignment, design residuals, thermal effects, and other other associated phenomena…

Instrumentation and Methods for Astrophysics · Physics 2021-07-28 Eric B. Bechter , Andrew J. Bechter , Justin R. Crepp , Jonathan Crass

As wireless networks transition toward 6G, high mobility, clustered scattering, and hardware impairments increasingly challenge classical assumptions on channel sparsity, resolvability, and stationarity. In these regimes, performance…

Signal Processing · Electrical Eng. & Systems 2026-05-05 Hamza Haif , Abdelali Arous , Huseyin Arslan

Any frequency selective device with an ongoing drift will cause observed spectra to be variously and simultaneously scaled in proportion to their source distances. The reason is that detectors after the drifting selection will integrate…

General Physics · Physics 2008-12-05 V. Guruprasad

Sample selection is a necessary preparation for weak lensing measurement. It is well-known that selection itself may introduce bias in the measured shear signal. Using image simulation and the Fourier_Quad shear measurement pipeline, we…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-04 Hekun Li , Jun Zhang , Dezi Liu , Wentao Luo , Jiajun Zhang , Fuyu Dong , Zhi Shen , Haoran Wang

We investigate energy-leaky modes induced by incomplete measurements of the scattering matrices of complex media. Due to the limited numerical apertures of an optical system, it is experimentally challenging to access theoretically…

Optics · Physics 2016-03-23 Hyeonseung Yu , KyeoReh Lee , YongKeun Park

We derive general equations for non-linearity corrections and statistical uncertainty (variance) estimates for data acquired with near-infrared detectors employing correlated double sampling, multiple correlated double sampling (Fowler…

Astrophysics · Physics 2009-11-10 W. D. Vacca , M. C. Cushing , J. T. Rayner

Quantum phase estimation is an important component in diverse quantum algorithms. However, it suffers from spectral leakage, when the reciprocal of the record length is not an integer multiple of the unknown phase, which incurs an accuracy…

Quantum Physics · Physics 2022-05-17 Yifeng Xiong , Soon Xin Ng , Gui-Lu Long , Lajos Hanzo

Estimation of near-wall turbulence in channel flow from outer observations is investigated using adjoint-variational data assimilation. We first consider fully resolved velocity data, starting at a distance from the wall. By enforcing the…

Fluid Dynamics · Physics 2025-04-09 Mengze Wang , Tamer A. Zaki

Optical spectroscopy is a fundamental tool in numerous areas of science and technology. Much effort has focused on miniaturizing spectrometers, but thus far at the cost of high spectral resolution and broad operating range. Here, we…

Process of the nonlinear deformation of the shallow water wave in a basin of constant depth is studied. The characteristics of the first breaking are analyzed in details. The Fourier spectrum and steepness of the nonlinear wave is…

Exactly Solvable and Integrable Systems · Physics 2007-05-23 Narcisse Zahibo , Irina Didenkulova , Andrey Kurkin , Efim Pelinovsky

In non-destructive evaluation guided wave inspections, the elastic structure to be inspected is often embedded within other elastic media and the ensuing leaky waves are complex and non-trivial to compute; we consider the canonical example…

Numerical Analysis · Mathematics 2024-07-04 Evripides Georgiades , Michael J. S. Lowe , Richard V. Craster

Network theory and inverse modeling are two standard tools of applied physics, whose combination is needed when studying the dynamical organization of spatially distributed systems from indirect measurements. However, the associated…

Data Analysis, Statistics and Probability · Physics 2015-01-30 Vincent Wens

Polarimetric observations are affected by leakage of unpolarized light into the polarization channels, in a way that varies with the angular position of the source relative to the optical axis. The off-axis part of the leakage is often…

Astrophysics · Physics 2015-05-13 R. I. Reid , A. D. Gray , T. L. Landecker , A. G. Willis
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