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Spectral estimators are fundamental in lowrank matrix models and arise throughout machine learning and statistics, with applications including network analysis, matrix completion and PCA. These estimators aim to recover the leading…

Statistics Theory · Mathematics 2025-02-17 Hao Yan , Keith Levin

Quantum algorithms are well-suited to calculate estimates of the energy spectra for spin lattice systems. These algorithms are based on the efficient calculation of the discrete Fourier components of the density of states. The efficiency of…

Quantum Physics · Physics 2009-11-07 Cyrus P. Master , Fumiko Yamaguchi , Yoshihisa Yamamoto

Exact analytical expressions for the cross-section correlation functions of chaotic scattering sys- tems have hitherto been derived only under special conditions. The objective of the present article is to provide expressions that are…

Chaotic Dynamics · Physics 2016-10-19 Torleif Ericson , Barbara Dietz , Achim Richter

In this paper, a new method based on Greens function theory and Fourier transform analysis has been proposed for calculating band structure with high accuracy and low processing time. This method utilizes sampling of potential energy in…

Materials Science · Physics 2012-07-13 Milad Khoshnegar , Amir Hossein Hosseinia , Nima Arjmandi , Sina Khorasani

The variation with energy of the total cross section for elastic electron scattering from atoms of several elements is caused primarily by shape resonances corresponding to the formation of temporary negative ions. It is shown that such…

Atomic Physics · Physics 2007-05-23 Peter Nicoletopoulos

We have carried out a timing analysis of Cyg X-1 and GRS 1915+105 using more than 5 years worth of data from the All Sky Monitor (ASM) on board RXTE. We have obtained for the first time power density spectra, colour-colour and…

Astrophysics · Physics 2009-11-07 P. Reig , I. Papadakis , N. D. Kylafis

We investigate the impact of limited data on training pairwise energy-based models for inverse problems aimed at identifying interaction networks. Utilizing the Gaussian model as testbed, we dissect training trajectories across the…

Machine Learning · Computer Science 2025-06-06 Giovanni Catania , Aurélien Decelle , Cyril Furtlehner , Beatriz Seoane

Electronic structure calculations based on many-body perturbation theory (e.g. GW or the random-phase approximation (RPA)) require function evaluations in the complex time and frequency domain, for example inhomogeneous Fourier transforms…

Spread-spectrum signals are increasingly adopted in fields including communications, testing of electronic systems, Electro-Magnetic Compatibility (EMC) enhancement, ultrasonic non-destructive testing. This paper considers the synthesis of…

Data Analysis, Statistics and Probability · Physics 2014-12-22 Sergio Callegari

The need to Fourier transform data sets with irregular sampling is shared by various domains of science. This is the case for example in astronomy or sismology. Iterative methods have been developed that allow to reach approximate…

Numerical Analysis · Mathematics 2024-01-23 Guy Perrin

Efficient estimators of Fourier-space statistics for large number of objects rely on Fast Fourier Transforms (FFTs), which are affected by aliasing from unresolved small scale modes due to the finite FFT grid. Aliasing takes the form of a…

Cosmology and Nongalactic Astrophysics · Physics 2017-10-09 Emiliano Sefusatti , Martin Crocce , Roman Scoccimarro , Hugh Couchman

Quantum chaotic and integrable systems are known to exhibit a characteristic $1/f$ and $1/f^{2}$ noise, respectively, in the power spectrum associated to their spectral fluctuations. A recent work [R. Riser, V. A. Osipov, and E. Kanzieper,…

Quantum Physics · Physics 2019-09-17 A. L. Corps , A. Relaño

A method is presented for investigating the periodic signal content of time series in which a number of signals is present, such as arising from the observation of multiperiodic oscillating stars in observational asteroseismology. Standard…

Astrophysics · Physics 2007-05-23 Frank P. Pijpers

We carry out a systematical study of the spectral lag properties of 50 single-pulsed Gamma-Ray Bursts (GRBs) detected by Fermi/GBM. By dividing the light curves into multiple consecutive energy channels we provide a new measurement of the…

High Energy Astrophysical Phenomena · Physics 2017-08-09 Lang Shao , Bin-Bin Zhang , Fu-Ri Wang , Xue-Feng Wu , Ye-Hao Cheng , Xi Zhang , Bang-Yao Yu , Bao-Jia Xi , Xue Wang , Huan-Xue Feng , Meng Zhang , Dong Xu

We investigate the X-ray variability characteristics of hard X-ray selected AGNs (based on Swift/BAT data) in the soft X-ray band using the RXTE/ASM data. The uncertainties involved in the individual dwell measurements of ASM are critically…

Astrophysics of Galaxies · Physics 2011-02-11 V. R. Chitnis , J. K. Pendharkar , D. Bose , V. K. Agrawal , A. R. Rao , R. Misra

We present experimental studies of the power spectrum and other fluctuation properties in the spectra of microwave networks simulating chaotic quantum graphs with violated time reversal in- variance. On the basis of our data sets we…

Chaotic Dynamics · Physics 2016-11-03 Malgorzata Bialous , Vitalii Yunko , Szymon Bauch , Michal Lawniczak , Barbara Dietz , Leszek Sirko

We consider an error model for phased array with gain errors and phase errors, with errors dependent on the phase applied and the antenna index. Under this model, we propose an algorithm for measuring the errors by selectively turning on…

Signal Processing · Electrical Eng. & Systems 2021-07-21 Joyson Sebastian , Pranav Dayal , Kee-Bong Song , Walid AliAhmad

Partial sum rules are widely used in physics to separate low- and high-energy degrees of freedom of complex dynamical systems. Their application, though, is challenged in practice by the always finite spectrometer bandwidth and is often…

Other Condensed Matter · Physics 2009-11-13 A. B. Kuzmenko , D. van der Marel , F. Carbone , F. Marsiglio

We examine the effect of a threshold bias on the power spectrum and the bispectrum in an ensemble of numerical simulations (Gaussian initial perturbations with power law spectra P(k) \sim k^n, n=+1, 0, -1, -2) and compare our results with…

Astrophysics · Physics 2015-06-24 J. N. Fry , Adrian L. Melott , Sergei F. Shandarin

We describe a non-perturbative method for computing the energy band structures of one-dimensional models with general point potentials sitting at equally spaced sites. This is done thanks to a Bethe ansatz approach and the method is…

Other Condensed Matter · Physics 2010-04-05 V. Caudrelier , N. Crampe
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