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Cosmological observables rely heavily on summary statistics such as two-point correlation functions. In many practical cases (e.g. the weak-lensing cosmic shear), those correlation functions are estimated from a finite, discrete sample of…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-24 Pierre Fleury

Source position time series produced by International VLBI Service for Geodesy and astrometry (IVS) Analysis Centers were analyzed. These series was computed using different software and analysis strategy. Comparison of this series showed…

Instrumentation and Methods for Astrophysics · Physics 2015-05-26 Zinovy Malkin

The 21 cm radiation of neutral hydrogen provides crucial information for studying the early universe and its evolution. To advance this research, countries have made significant investments in constructing large low-frequency radio…

Instrumentation and Methods for Astrophysics · Physics 2025-08-04 Ming-wei Qin , Rui Tang , Ying-hui Zhou , Chang-jun Lan , Wen-hao Fu , Huan Wang , Bao-lin Hou , Zamri , Jin-song Ping , Wen-jun Yang , Liang Dong

Characterising the noise of an airborne electromagnetic (AEM) system is critical in correctly imaging the earth's subsurface conductivity. Deterministic and probabilistic geophysical inversion algorithms require foreknowledge of the system…

Geophysics · Physics 2026-05-06 Tim Scarr , Anandaroop Ray , Ross C. Brodie

Anomaly detection in time series data, to identify points that deviate from normal behaviour, is a common problem in various domains such as manufacturing, medical imaging, and cybersecurity. Recently, Generative Adversarial Networks (GANs)…

Machine Learning · Computer Science 2025-05-27 Md Abul Bashar , Richi Nayak

We propose in this paper an original technique to predict global radiation using a hybrid ARMA/ANN model and data issued from a numerical weather prediction model (ALADIN). We particularly look at the Multi-Layer Perceptron. After…

Neural and Evolutionary Computing · Computer Science 2012-01-10 Cyril Voyant , Marc Muselli , Christophe Paoli , Marie Laure Nivet

In this work the significance of treating a set of measurements as a time series is being explored. Time Series Analysis (TSA) techniques, part of the Exploratory Data Analysis (EDA) approach, can provide much insight regarding the…

Data Analysis, Statistics and Probability · Physics 2012-03-01 Dimitra Georgakaki , Chris Mitsas , Hariton Polatoglou

Astrometry provides the foundation for astrophysics. Accurate positions are required for the association of sources detected at different times or wavelengths, and distances are essential to estimate the size, luminosity, mass, and ages of…

Instrumentation and Methods for Astrophysics · Physics 2015-06-18 M. J. Reid , M. Honma

Recent advances in Visual Anomaly Detection (VAD) have introduced sophisticated algorithms leveraging embeddings generated by pre-trained feature extractors. Inspired by these developments, we investigate the adaptation of such algorithms…

Astronomical time series from large-scale surveys like LSST are often irregularly sampled and incomplete, posing challenges for classification and anomaly detection. We introduce a new framework based on Neural Stochastic Delay Differential…

Machine Learning · Computer Science 2026-04-03 YongKyung Oh , Seungsu Kam , Dong-Young Lim , Sungil Kim

Since their first detection in 2015, gravitational wave observations have enabled a variety of studies, ranging from stellar evolution to fundamental physics. In this chapter, we focus on their use as "standard sirens", describing the…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-04 Antonella Palmese , Simone Mastrogiovanni

Variability of radio-emitting active galactic nuclei can be used to probe both intrinsic variations arising from shocks, flares, and other changes in emission from regions surrounding the central supermassive black hole, as well as…

High Energy Astrophysical Phenomena · Physics 2015-01-21 Hayley Bignall , Steve Croft , Talvikki Hovatta , Jun Yi Koay , Joseph Lazio , Jean-Pierre Macquart , Cormac Reynolds

The aim of this paper is to describe a novel non-parametric noise reduction technique from the point of view of Bayesian inference that may automatically improve the signal-to-noise ratio of one- and two-dimensional data, such as e.g.…

Instrumentation and Methods for Astrophysics · Physics 2023-07-07 Pablo M Sanchez-Alarcon , Yago Ascasibar Sequeiros

Gravitational wave detectors like the Einstein Telescope and LISA generate long multivariate time series, which pose significant challenges in spectral density estimation due to a number of overlapping signals as well as the presence of…

General Relativity and Quantum Cosmology · Physics 2024-09-23 Jianan Liu , Avi Vajpeyi , Renate Meyer , Kamiel Janssens , Jeung Eun Lee , Patricio Maturana-Russel , Nelson Christensen , Yixuan Liu

Pulsar timing-array correlation measurements offer an exciting opportunity to test the nature of gravity in the cosmologically novel nanohertz gravitational wave regime. The stochastic gravitational wave background is assumed Gaussian and…

General Relativity and Quantum Cosmology · Physics 2022-11-23 Reginald Christian Bernardo , Kin-Wang Ng

The effect of noise on the Inverse Synthetic Aperture Radar (ISAR) with sparse apertures is a challenging issue for image reconstruction with high resolution at low Signal-to-Noise Ratios (SNRs). It is well-known that the image resolution…

Signal Processing · Electrical Eng. & Systems 2024-06-18 Mohammad Roueinfar , Mohammad Hossein Kahaei

Many types of anomaly detection methods have been proposed recently, and applied to a wide variety of fields including medical screening and production quality checking. Some methods have utilized images, and, in some cases, a part of the…

Computer Vision and Pattern Recognition · Computer Science 2018-10-08 Minori Narita , Daiki Kimura , Ryuki Tachibana

In this paper we consider estimating the system parameters and designing stable observer for unknown noisy linear time-invariant (LTI) systems. We propose a Support Vector Regression (SVR) based estimator to provide adjustable asymmetric…

Systems and Control · Electrical Eng. & Systems 2022-05-17 Xuda Ding , Han Wang , Jianping He , Cailian Chen , Xinping Guan

Reaching the thermal noise at low frequencies with the next generation of instruments (e.g. SKA, LOFAR etc.) is going to be a challenge. It requires the development of more advanced techniques of calibration compared to those used from the…

Instrumentation and Methods for Astrophysics · Physics 2010-08-31 Emanuela Orrú , Huib Intema

A variety of statistical methods for understanding variability in the time domain for low count rate X-ray and gamma-ray sources are explored. Variability can be detected using nonparametric (Anderson-Darling and overdispersion tests) and…

Instrumentation and Methods for Astrophysics · Physics 2023-05-24 Eric D. Feigelson , Vinay L. Kashyap , Aneta Siemiginowska