<?xml version="1.0" encoding="utf-8" standalone="yes"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>Article | Patrick Koller</title><link>https://patch0816.github.io/publication-type/article/</link><atom:link href="https://patch0816.github.io/publication-type/article/index.xml" rel="self" type="application/rss+xml"/><description>Article</description><generator>Hugo Blox Builder (https://hugoblox.com)</generator><language>en-us</language><lastBuildDate>Wed, 15 Apr 2026 00:00:00 +0000</lastBuildDate><image><url>https://patch0816.github.io/media/icon_hu3661d5716fb1fb87a460a392592f4033_20786_512x512_fill_lanczos_center_3.png</url><title>Article</title><link>https://patch0816.github.io/publication-type/article/</link></image><item><title>Irregularly Sampled Time Series Interpolation for Binary Evolution Simulations Using Dynamic Time Warping</title><link>https://patch0816.github.io/publication/2026-dtw/</link><pubDate>Wed, 15 Apr 2026 00:00:00 +0000</pubDate><guid>https://patch0816.github.io/publication/2026-dtw/</guid><description>&lt;p>&lt;a href="https://sites.northwestern.edu/ivpl/people/" target="_blank" rel="noopener">Ugur Demir&lt;/a>, &lt;a href="https://sites.northwestern.edu/ivpl/people/" target="_blank" rel="noopener">Philipp M Srivastava&lt;/a>, &lt;a href="https://www.mccormick.northwestern.edu/research-faculty/directory/profiles/katsaggelos-aggelos.html" target="_blank" rel="noopener">Aggelos K. Katsaggelos&lt;/a>, &lt;a href="https://physics.northwestern.edu/people/faculty/core-faculty/vicky-kalogera.html" target="_blank" rel="noopener">Vicky Kalogera&lt;/a>, &lt;a href="https://sites.northwestern.edu/ivpl/people/" target="_blank" rel="noopener">Santiago L Tapia&lt;/a>, &lt;a href="https://3dim.optics.arizona.edu/author/manuel-ballester/" target="_blank" rel="noopener">Manuel Ballester&lt;/a>, &lt;a href="https://scholar.google.com/citations?user=o5u5qXEAAAAJ&amp;amp;hl=en" target="_blank" rel="noopener">Shamal Lalvani&lt;/a>, &lt;strong>Patrick Koller&lt;/strong>, &lt;a href="https://phys.ufl.edu/people/faculty/jeff-andrews/" target="_blank" rel="noopener">Jeff J Andrews&lt;/a>, &lt;a href="https://sgossage.github.io/" target="_blank" rel="noopener">Seth Gossage&lt;/a>, &lt;a href="https://maxbriel.com/" target="_blank" rel="noopener">Max M Briel&lt;/a>, and &lt;a href="https://scholar.google.com/citations?user=gbFJzbMAAAAJ&amp;amp;hl=en" target="_blank" rel="noopener">Elizabeth Teng&lt;/a>&lt;/p>
&lt;h3 id="abstract">Abstract&lt;/h3>
&lt;p>This research addresses the computational bottleneck of population synthesis by introducing a robust interpolation scheme for binary stars. Unlike single-star evolution, binary tracks are often irregularly sampled and plagued by misaligned evolutionary phases due to mutual interactions.&lt;/p>
&lt;p>By employing Dynamic Time Warping (DTW), we generate a joint alignment that preserves the underlying microphysics across the entire track, enabling the rapid generation of high-fidelity binary models for large-scale simulations like &lt;a href="https://posydon.org/" target="_blank" rel="noopener">POSYDON&lt;/a>.&lt;/p>
&lt;h3 id="bibtex-citation">BibTeX Citation&lt;/h3>
&lt;div class="highlight">&lt;pre tabindex="0" class="chroma">&lt;code class="language-bibtex" data-lang="bibtex">&lt;span class="line">&lt;span class="cl">&lt;span class="nc">@misc&lt;/span>&lt;span class="p">{&lt;/span>&lt;span class="nl">demir2026irregularlysampledtimeseries&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">title&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{Irregularly Sampled Time Series Interpolation for Binary Evolution Simulations Using Dynamic Time Warping}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">author&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{Ugur Demir and Philipp M. Srivastava and Aggelos Katsaggelos and Vicky Kalogera and Santiago L. Tapia and Manuel Ballester and Shamal Lalvani and Patrick Koller and Jeff J. Andrews and Seth Gossage and Max M. Briel and Elizabeth Teng}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">year&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{2026}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">eprint&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{2604.13604}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">archivePrefix&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{arXiv}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">primaryClass&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{astro-ph.SR}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">url&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{https://arxiv.org/abs/2604.13604}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl">&lt;span class="p">}&lt;/span>
&lt;/span>&lt;/span>&lt;/code>&lt;/pre>&lt;/div></description></item><item><title>Learning the Stellar Structure Equations via Self-supervised Physics-Informed Neural Networks</title><link>https://patch0816.github.io/publication/2026-learning-the-stellar-structure-equations-pinn/</link><pubDate>Mon, 06 Apr 2026 00:00:00 +0000</pubDate><guid>https://patch0816.github.io/publication/2026-learning-the-stellar-structure-equations-pinn/</guid><description>&lt;p>&lt;a href="https://3dim.optics.arizona.edu/author/manuel-ballester/" target="_blank" rel="noopener">Manuel Ballester&lt;/a>, &lt;a href="https://sites.northwestern.edu/ivpl/people/" target="_blank" rel="noopener">Santiago Lopez-Tapia&lt;/a>, &lt;a href="https://sgossage.github.io/" target="_blank" rel="noopener">Seth Gossage&lt;/a>, &lt;strong>Patrick Koller&lt;/strong>, &lt;a href="https://sites.northwestern.edu/ivpl/people/" target="_blank" rel="noopener">Philipp M Srivastava&lt;/a>, &lt;a href="https://sites.northwestern.edu/ivpl/people/" target="_blank" rel="noopener">Ugur Demir&lt;/a>, &lt;a href="https://yongseokjo.com/" target="_blank" rel="noopener">Yongseok Jo&lt;/a>, &lt;a href="https://scholar.google.com/citations?user=k3CRBwsAAAAJ&amp;amp;hl=es" target="_blank" rel="noopener">Almudena P Marquez&lt;/a>, &lt;a href="https://www.ost.ch/en/person/christoph-wuersch-8300" target="_blank" rel="noopener">Christoph Würsch&lt;/a>, &lt;a href="https://www.csccm.in/our-team" target="_blank" rel="noopener">Souvik Chakraborty&lt;/a>, &lt;a href="https://physics.northwestern.edu/people/faculty/core-faculty/vicky-kalogera.html" target="_blank" rel="noopener">Vicky Kalogera&lt;/a>, and &lt;a href="https://www.mccormick.northwestern.edu/research-faculty/directory/profiles/katsaggelos-aggelos.html" target="_blank" rel="noopener">Aggelos K. Katsaggelos&lt;/a>&lt;/p>
&lt;h3 id="abstract">Abstract&lt;/h3>
&lt;p>This research introduces a mesh-free approach to solving the fundamental equations of stellar structure using Physics-Informed Neural Networks (PINNs). By enforcing hydrostatic and thermal equilibrium constraints directly within the loss function, we eliminate the need for traditional grid-based discretization used in solvers like &lt;a href="https://docs.mesastar.org" target="_blank" rel="noopener">MESA&lt;/a>.&lt;/p>
&lt;p>Our framework incorporates auxiliary neural surrogates for microphysics (opacities and equation of state), allowing the model to learn continuous, differentiable radial profiles across a wide range of stellar masses.&lt;/p>
&lt;h3 id="bibtex-citation">BibTeX Citation&lt;/h3>
&lt;div class="highlight">&lt;pre tabindex="0" class="chroma">&lt;code class="language-bibtex" data-lang="bibtex">&lt;span class="line">&lt;span class="cl">&lt;span class="nc">@misc&lt;/span>&lt;span class="p">{&lt;/span>&lt;span class="nl">ballester2026learningstellarstructure&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">title&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{Learning the Stellar Structure Equations via Self-supervised Physics-Informed Neural Networks}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">author&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{Manuel Ballester and Santiago Lopez-Tapia and Seth Gossage and Patrick Koller and Philipp M. Srivastava and Ugur Demir and Yongseok Jo and Almudena P. Marquez and Christoph Wuersch and Souvik Chakraborty and Vicky Kalogera and Aggelos Katsaggelos}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">year&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{2026}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">eprint&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{2604.06255}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">archivePrefix&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{arXiv}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">primaryClass&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{astro-ph.SR}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl"> &lt;span class="na">url&lt;/span>&lt;span class="p">=&lt;/span>&lt;span class="s">{https://arxiv.org/abs/2604.06255}&lt;/span>&lt;span class="p">,&lt;/span>
&lt;/span>&lt;/span>&lt;span class="line">&lt;span class="cl">&lt;span class="p">}&lt;/span>
&lt;/span>&lt;/span>&lt;/code>&lt;/pre>&lt;/div></description></item></channel></rss>