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We present a comprehensive analysis of the 21 cm intensity mapping (IM) data from the Tianlai Cylinder Pathfinder Array (TCPA), focusing on multi-scale foreground mitigation and three-dimensional power spectrum estimation. Utilizing 20 days…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-01 Yikai Deng , Shifan Zuo , Jixia Li , Yougang Wang , Xuelei Chen

Twenty-one centimeter tomography is emerging as a powerful tool to explore the end of the cosmic dark ages and the reionization epoch, but it will only be as good as our ability to accurately model and remove astrophysical foreground…

Astrophysics · Physics 2008-11-26 Xiaomin Wang , Max Tegmark , Mario Santos , Lloyd Knox

Tracing of the magnetic field with Velocity Gradient Technique (VGT) allows observers to probe magnetic field directions with spectroscopic data. In this paper, we employ the method of Principal Component Analysis (PCA) to extract the…

Astrophysics of Galaxies · Physics 2018-07-25 Yue Hu , Ka Ho Yuen , A. Lazarian

To mitigate the severe information loss arising from widely adopted linear scale cuts in constraints on modified gravity parameterisations with Weak Lensing (WL) and Large-Scale Structure (LSS) data, we introduce a novel alternative method…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-10 C. M. A. Zanoletti , C. D. Leonard

We present a new straightforward principal component analysis (PCA) method based on the diagonalization of the weighted variance-covariance matrix through two spectral decomposition methods: power iteration and Rayleigh quotient iteration.…

Instrumentation and Methods for Astrophysics · Physics 2014-12-16 Ludovic Delchambre

Mapping the distribution of neutral atomic hydrogen (HI) in the Universe through its 21 cm emission line provides a powerful cosmological probe to map the large-scale structures and shed light on various cosmological phenomena. The Baryon…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-20 Albin Joseph , Rajib Saha

Principal component pursuit (PCP) is a state-of-the-art approach for background estimation problems. Due to their higher computational cost, PCP algorithms, such as robust principal component analysis (RPCA) and its variants, are not…

Computer Vision and Pattern Recognition · Computer Science 2017-07-04 Aritra Dutta , Xin Li , Peter Richtárik

Principal Component Analysis (PCA) is a widely utilized technique for dimensionality reduction; however, its inherent lack of interpretability-stemming from dense linear combinations of all feature-limits its applicability in many domains.…

Machine Learning · Computer Science 2025-04-01 Loc Hoang Tran

Ground-based observations at thermal infrared wavelengths suffer from large background radiation due to the sky, telescope and warm surfaces in the instrument. This significantly limits the sensitivity of ground-based observations at…

Instrumentation and Methods for Astrophysics · Physics 2018-03-16 Silvan Hunziker , Sascha P. Quanz , Adam Amara , Michael R. Meyer

Recent works in self-supervised learning have shown impressive results on single-object images, but they struggle to perform well on complex multi-object images as evidenced by their poor visual grounding. To demonstrate this concretely, we…

Computer Vision and Pattern Recognition · Computer Science 2023-06-27 Aishwarya Agarwal , Srikrishna Karanam , Balaji Vasan Srinivasan

Purpose: Introducing "compensated variable-prephasing" (CVP), a phantom-based method for gradient waveform measurements. The technique is based on the "variable-prephasing" (VP) method, but takes into account the effects of all gradients…

Medical Physics · Physics 2024-09-12 Hannah Scholten , Tobias Wech , Istvan Homolya , Herbert Köstler

Zero-Shot Anomaly Detection (ZSAD) leverages Vision-Language Models (VLMs) to enable supervision-free industrial inspection. However, existing ZSAD paradigms are constrained by single visual backbones, which struggle to balance global…

Computer Vision and Pattern Recognition · Computer Science 2026-01-21 Chenhao Fu , Han Fang , Xiuzheng Zheng , Wenbo Wei , Yonghua Li , Hao Sun , Xuelong Li

We introduce a novel algorithm that computes the $k$-sparse principal component of a positive semidefinite matrix $A$. Our algorithm is combinatorial and operates by examining a discrete set of special vectors lying in a low-dimensional…

Machine Learning · Statistics 2014-05-09 Dimitris S. Papailiopoulos , Alexandros G. Dimakis , Stavros Korokythakis

Support Vector Machines (SVMs) are a relatively new supervised classification technique to the land cover mapping community. They have their roots in Statistical Learning Theory and have gained prominence because they are robust, accurate…

Machine Learning · Computer Science 2007-11-20 Gidudu Anthony , Hulley Gregg , Marwala Tshilidzi

Singular Spectrum Analysis (SSA) or Singular Value Decomposition (SVD) are often used to de-noise univariate time series or to study their spectral profile. Both techniques rely on the eigendecomposition of the cor- relation matrix…

Signal Processing · Electrical Eng. & Systems 2018-07-30 A. M. Tomé , D. Malafaia , A. R. Teixeira , E. W. Lang

Capturing patterns of variation present in a dataset is important in exploratory data analysis and unsupervised learning. Contrastive dimension reduction methods, such as contrastive principal component analysis (cPCA), find patterns unique…

Machine Learning · Computer Science 2021-04-19 Robin Tu , Alexander H. Foss , Sihai D. Zhao

The Singular Value Decomposition (SVD) is one of the most important matrix factorizations, enjoying a wide variety of applications across numerous application domains. In statistics and data analysis, the common applications of SVD such as…

Mathematical Software · Computer Science 2020-09-03 Drew Schmidt

We compare various foreground removal techniques that are being utilised to remove bright foregrounds in various experiments aiming to detect the redshifted 21cm signal of neutral hydrogen from the Epoch of Reionization. In this work, we…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-17 Ian Hothi , Emma Chapman , Jonathan R. Pritchard , F. G. Mertens , L. V. E Koopmans , B. Ciardi , B. K. Gehlot , R. Ghara , A. Ghosh , S. K. Giri , I. T. Iliev , V. Jelić , S. Zaroubi

Singular Value Decomposition (SVD) has become an important technique for reducing the computational burden of Vision Language Models (VLMs), which play a central role in tasks such as image captioning and visual question answering. Although…

Computer Vision and Pattern Recognition · Computer Science 2026-04-06 Haiyu Wang , Yutong Wang , Jack Jiang , Sai Qian Zhang

We introduce a unified framework for evaluating dimensionality reduction techniques in spatial transcriptomics beyond standard PCA approaches. We benchmark six methods PCA, NMF, autoencoder, VAE, and two hybrid embeddings on a…

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