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Clustering is essential in data analysis and machine learning, but traditional algorithms like $k$-means and Gaussian Mixture Models (GMM) often fail with nonconvex clusters. To address the challenge, we introduce the Flexible Bivariate…

Machine Learning · Computer Science 2025-02-28 Yung-Peng Hsu , Hung-Hsuan Chen

We introduce a new method for robust beamforming, where the goal is to estimate a signal from array samples when there is uncertainty in the angle of arrival. Our method offers state-of-the-art performance on narrowband signals and is…

Signal Processing · Electrical Eng. & Systems 2024-06-25 Nakul Singh , Coleman DeLude , Mark A. Davenport , Justin Romberg

We present a novel maximum a posteriori estimator to jointly estimate band-powers and the covariance of the three-dimensional power spectrum (P3D) of Lyman-alpha forest flux fluctuations, called MAPLE. Our Wiener-filter based algorithm…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-27 Benjamin Horowitz , Roger de Belsunce , Zarija Lukic

Oscillating shapes of the primordial bispectrum are present in many inflationary models. The Planck experiment has recently published measurements of oscillating shapes, which were however limited to the efficient frequency range of the…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-22 M. Münchmeyer , F. Bouchet , M. Jackson , B. Wandelt

It is crucial to learn the shared structures among functional predictors, as these structures characterize how predictor components exert common effects and, more generally, how predictors are homogeneously associated with the response.…

Methodology · Statistics 2026-04-27 Shuhao Jiao , Hernando Ombao , Ian W. McKeague

Recent progress in high sensitivity Cosmic Microwave Background (CMB) polarization experiments opens up a window on large scale structure (LSS), as CMB polarization fluctuations on small angular scales can arise from a combination of LSS…

Cosmology and Nongalactic Astrophysics · Physics 2018-06-20 Chang Feng , Gilbert Holder

Triple sum-frequency (TSF) spectroscopy is a recently-developed methodology that enables collection of multidimensional spectra by resonantly exciting multiple quantum coherences of vibrational and electronic states. This work reports the…

Optics · Physics 2018-08-23 Darien J. Morrow , Daniel D. Kohler , Kyle J. Czech , John C. Wright

The direct evaluation of manifestly optimal, cut-sky CMB power spectrum and bispectrum estimators is numerically very costly, due to the presence of inverse-covariance filtering operations. This justifies the investigation of alternative…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-01 H. F. Gruetjen , J. R. Fergusson , M. Liguori , E. P. S. Shellard

Conventional algorithms for galaxy power spectrum estimation measure the true spectrum convolved with a survey window function, which, for parameter inference, must be compared with a similarly convolved theory model. In this work, we…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-12 Oliver H. E. Philcox

Censored quantile regression (CQR) has become a valuable tool to study the heterogeneous association between a possibly censored outcome and a set of covariates, yet computation and statistical inference for CQR have remained a challenge…

Statistics Theory · Mathematics 2022-10-25 Xuming He , Xiaoou Pan , Kean Ming Tan , Wen-Xin Zhou

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 introduce a new estimator of the CMB lensing power spectrum, together with its likelihood, based on iterative lensing reconstruction. Despite the increased complexity of the lensing maps, this estimator shares similarities with the…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-17 Louis Legrand , Julien Carron

Transformer-based models are at the forefront in long time-series forecasting (LTSF). While in many cases, these models are able to achieve state of the art results, they suffer from a bias toward low-frequencies in the data and high…

Machine Learning · Computer Science 2026-05-13 Elisha Dayag , Nhat Thanh Van Tran , Jack Xin

The bispectrum is the leading non-Gaussian statistic in large-scale structure, carrying valuable information on cosmology that is complementary to the power spectrum. To access this information, we need to model the bispectrum in the weakly…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-12 Tobias Baldauf , Mathias Garny , Petter Taule , Theo Steele

Nonlinearities in the gravitational evolution, galaxy bias, and redshift-space distortion drive the observed galaxy density fields away from the initial near-Gaussian states. Exploiting such a non-Gaussian galaxy density field requires…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-04 Joseph Tomlinson , Donghui Jeong , Juhan Kim

The characterization of exoplanet atmospheres using direct imaging spectroscopy requires high-contrast over a wide wavelength range. We study a recently proposed focal plane wavefront estimation algorithm that exclusively uses broadband…

Instrumentation and Methods for Astrophysics · Physics 2021-08-19 Susan F. Redmond , Laurent Pueyo , Leonid Pogorelyuk , James Noss , Scott D. Will , Iva Laginja , N. Jeremy Kasdin , Marshall D. Perrin , Remi Soummer

Estimation of the mean vector and covariance matrix is of central importance in the analysis of multivariate data. In the framework of generalized linear models, usually the variances are certain functions of the means with the normal…

Methodology · Statistics 2023-01-25 Anupam Kundu , Mohsen Pourahmadi

This paper studies two spectrum estimation methods for the case that the samples are obtained at a rate lower than the Nyquist rate. The first method is the correlogram method for undersampled data. The algorithm partitions the spectrum…

Statistics Theory · Mathematics 2013-11-25 Mahdi Shaghaghi , Sergiy A. Vorobyov

The classical structure-function (SF) method in fully developed turbulence or for scaling processes in general is influenced by large-scale energetic structures, known as infrared effect. Therefore, the extracted scaling exponents…

Fluid Dynamics · Physics 2015-06-18 Y. X. Huang

Time-resolved femtosecond stimulated Raman spectroscopy (FSRS) is a powerful tool for investigating ultrafast structural and vibrational dynamics in light absorbing systems. However, the technique generally requires exposing a sample to…

Instrumentation and Detectors · Physics 2018-07-10 Matthew N. Ashner , William A. Tisdale