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A fundamental bimodality of galaxies in the local Universe is apparent in many of the features used to describe them. Multiple sub-populations exist within this framework, each representing galaxies following distinct evolutionary pathways.…

Microclimate models are essential for linking climate to ecological processes, yet most physically based frameworks estimate temperature independently for each spatial unit and rely on simplified representations of lateral heat exchange. As…

Machine Learning · Computer Science 2026-03-17 Idan Sulami , Alon Itzkovitch , Michael R. Kearney , Moni Shahar , Ofir Levy

Application of K-Means algorithm is restricted by the fact that the number of clusters should be known beforehand. Previously suggested methods to solve this problem are either ad hoc or require parametric assumptions and complicated…

Machine Learning · Computer Science 2019-12-05 Sukavanan Nanjundan , Shreeviknesh Sankaran , C. R. Arjun , G. Paavai Anand

By utilizing large-scale graph analytic tools implemented in the modern Big Data platform, Apache Spark, we investigate the topological structure of gravitational clustering in five different universes produced by cosmological $N$-body…

Cosmology and Nongalactic Astrophysics · Physics 2020-03-04 Sungryong Hong , Donghui Jeong , Ho Seong Hwang , Juhan Kim , Sungwook E. Hong , Changbom Park , Arjun Dey , Milos Milosavljevic , Karl Gebhardt , Kyoung-Soo Lee

We suggest a novel method of clustering and exploratory analysis of temporal event sequences data (also known as categorical time series) based on three-dimensional data grid models. A data set of temporal event sequences can be represented…

Databases · Computer Science 2015-05-07 Dominique Gay , Romain Guigourès , Marc Boullé , Fabrice Clérot

We present the mass-X-ray observable scaling relationships for clusters of galaxies using the XMM-Newton cluster catalog of Snowden et al. Our results are roughly consistent with previous observational and theoretical work, with one major…

High Energy Astrophysical Phenomena · Physics 2015-05-14 Adrienne M. Juett , David S. Davis , Richard Mushotzky

Evolution of the cluster temperature function is extremely sensitive to the mean matter density of the universe. Current measurements based on cluster temperature surveys indicate that Omega_M ~ 0.3 with a 1-sigma statistical error ~0.1,…

Astrophysics · Physics 2009-10-31 G. M. Voit

Galaxy clusters exhibit regular scaling relations among their bulk properties. These relations establish vital links between halo mass and cluster observables. Precision cosmology studies that depend on these links benefit from a better…

Astrophysics · Physics 2009-11-13 David A. Ventimiglia , G. Mark Voit , Megan Donahue , S. Ameglio

The k-means algorithm is a partitional clustering method. Over 60 years old, it has been successfully used for a variety of problems. The popularity of k-means is in large part a consequence of its simplicity and efficiency. In this paper…

Computer Vision and Pattern Recognition · Computer Science 2013-06-11 Ognjen Arandjelovic

We discuss statistical techniques for detecting and quantifying bimodality in astronomical datasets. We concentrate on the KMM algorithm, which estimates the statistical significance of bimodality in such datasets and objectively partitions…

Astrophysics · Physics 2009-10-22 Keith M. Ashman , Christina M. Bird , Steven E. Zepf

The large amount of data on galaxies, up to higher and higher redshifts, asks for sophisticated statistical approaches to build adequate classifications. Multivariate cluster analyses, that compare objects for their global similarities, are…

Cosmology and Nongalactic Astrophysics · Physics 2011-06-22 Didier Fraix-Burnet

Global Climate Models (GCMs) are the primary tool to simulate climate evolution and assess the impacts of climate change. However, they often operate at a coarse spatial resolution that limits their accuracy in reproducing local-scale…

Atmospheric and Oceanic Physics · Physics 2023-08-04 Jose González-Abad , Álex Hernández-García , Paula Harder , David Rolnick , José Manuel Gutiérrez

We study the problem of clustering sequences of unlabeled point sets taken from a common metric space. Such scenarios arise naturally in applications where a system or process is observed in distinct time intervals, such as biological…

Data Structures and Algorithms · Computer Science 2017-10-17 Tamal K. Dey , Alfred Rossi , Anastasios Sidiropoulos

Air pollution is a major global health hazard, with fine particulate matter (PM10) linked to severe respiratory and cardiovascular diseases. Hence, analyzing and clustering spatio-temporal air quality data is crucial for understanding…

Methodology · Statistics 2025-06-02 Luca Aiello , Raffaele Argiento , Sirio Legramanti , Lucia Paci

Incremental K-means and DBSCAN are two very important and popular clustering techniques for today's large dynamic databases (Data warehouses, WWW and so on) where data are changed at random fashion. The performance of the incremental…

Databases · Computer Science 2014-06-19 Sanjay Chakraborty , N. K. Nagwani , Lopamudra Dey

Understanding and representing complex climate variability is essential for both scientific analysis and predictive modeling. However, identifying meaningful climate regimes from raw variables is challenging, as they exhibit high noise and…

Machine Learning · Computer Science 2026-04-28 Lívia Meinhardt , Dário Oliveira

We consider panel data models with group structure. We study the asymptotic behavior of least-squares estimators and information criterion for the number of groups, allowing for the presence of small groups that have an asymptotically…

Econometrics · Economics 2025-08-22 Mikihito Nishi

We develop new econometric methods for the comparison of nonparametric time trends. In many applications, practitioners are interested in whether the observed time series all have the same time trend. Moreover, they would often like to know…

Econometrics · Economics 2022-09-23 Marina Khismatullina , Michael Vogt

Clustering real world data often faced with curse of dimensionality, where real world data often consist of many dimensions. Multidimensional data clustering evaluation can be done through a density-based approach. Density approaches based…

Databases · Computer Science 2010-12-30 Rahmat Widia Sembiring , Jasni Mohamad Zain

In cluster analysis, a common first step is to scale the data aiming to better partition them into clusters. Even though many different techniques have throughout many years been introduced to this end, it is probably fair to say that the…

Machine Learning · Computer Science 2023-05-30 Eduardo J. Aguilar , Valmir C. Barbosa