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We present TREVR2 (Tree-based REVerse Ray Tracing 2), a fast, general algorithm for computing the radiation field, suitable for both particle and mesh codes. It is designed to self-consistently evolve chemistry for zoomed-in astrophysical…

Instrumentation and Methods for Astrophysics · Physics 2024-01-18 James W. Wadsley , Bernhard Baumschlager , Sijing Shen

The treatment of radiative transfer with multiple radiation sources is a critical challenge in simulations of star formation and the interstellar medium. In this paper we present the novel TreeRay method for solving general radiative…

Instrumentation and Methods for Astrophysics · Physics 2021-06-30 Richard Wünsch , Stefanie Walch , František Dinnbier , Daniel Seifried , Sebastian Haid , Andre Klepitko , Anthony P. Whitworth , Jan Palouš

We describe a novel adaptive ray tracing scheme to solve the equation of radiative transfer around point sources in hydrodynamical simulations. The angular resolution adapts to the local hydrodynamical resolution and hence is of use for…

Astrophysics · Physics 2009-11-07 Tom Abel , Benjamin D. Wandelt

We have developed an algorithm for transferring radiation in three-dimensional space. The algorithm computes radiation source and sink terms using the Fast Fourier Transform (FFT) method, based on a formulation in which the integral of any…

Astrophysics · Physics 2009-11-07 Renyue Cen

In this paper, we investigate adaptive nonlinear regression and introduce tree based piecewise linear regression algorithms that are highly efficient and provide significantly improved performance with guaranteed upper bounds in an…

Machine Learning · Computer Science 2013-12-30 N. Denizcan Vanli , Suleyman S. Kozat

Implicit Neural Representations for Videos (NeRV) have emerged as a powerful paradigm for video representation, enabling direct mappings from frame indices to video frames. However, existing NeRV-based methods do not fully exploit temporal…

Computer Vision and Pattern Recognition · Computer Science 2025-04-18 Jiancheng Zhao , Yifan Zhan , Qingtian Zhu , Mingze Ma , Muyao Niu , Zunian Wan , Xiang Ji , Yinqiang Zheng

In view synthesis, a neural radiance field approximates underlying density and radiance fields based on a sparse set of scene pictures. To generate a pixel of a novel view, it marches a ray through the pixel and computes a weighted sum of…

Computer Vision and Pattern Recognition · Computer Science 2024-03-05 Nikita Morozov , Denis Rakitin , Oleg Desheulin , Dmitry Vetrov , Kirill Struminsky

We present a ray-tracing technique for radiative transfer modeling of complex three-dimensional (3D) structures which include dense regions of high optical depth like in dense molecular clouds, circumstellar disks, envelopes of evolved…

Astrophysics · Physics 2009-11-11 J. Steinacker , A. Bacmann , Th. Henning

In this paper we analyze the performance of time-reversal (TR) techniques in conjunction with various Ground Penetrating Radar (GPR) pre-processing methods aimed at improving detection of subsurface targets. TR techniques were first…

Geophysics · Physics 2017-10-11 Vinicius R. N. Santos , Fernando L. Teixeira

We present a new method for estimating the Neural Reflectance Field (NReF) of an object from a set of posed multi-view images under unknown lighting. NReF represents 3D geometry and appearance of objects in a disentangled manner, and are…

Computer Vision and Pattern Recognition · Computer Science 2022-10-11 Xiu Li , Xiao Li , Yan Lu

The simulation of electrical discharges has been attracting a great deal of attention. In such simulations, the electric field computation dominates the computational time. In this paper, we propose a fast tree algorithm that helps to…

Computational Engineering, Finance, and Science · Computer Science 2018-07-04 Chijie Zhuang , Yong Zhang , Xin Zhou , Rong Zeng , Jinliang He , Lei Liu

In this work, we present the tree tensor network Nystr\"om (TTNN), an algorithm that extends recent research on streamable tensor approximation, such as for Tucker and tensor-train formats, to the more general tree tensor network format,…

Numerical Analysis · Mathematics 2024-12-10 Alberto Bucci , Gianfranco Verzella

Radiation is an important contributor to the energetics of the interstellar medium, yet its transport is difficult to solve numerically. We present a novel approach towards solving radiative transfer of diffuse sources via backwards ray…

Instrumentation and Methods for Astrophysics · Physics 2023-02-15 A. Klepitko , S. Walch , R. Wünsch , D. Seifried , F. Dinnbier , S. Haid

We implement machine learning algorithms to nuclear data. These algorithms are purely data driven and generate models that are capable to capture intricate trends. Gradient boosted trees algorithm is employed to generate a trained model…

Nuclear Theory · Physics 2019-07-24 Nishchal R. Dwivedi

We present a new numerical scheme to solve the transfer of diffuse radiation on three-dimensional mesh grids which is efficient on processors with highly parallel architecture such as recently popular GPUs and CPUs with multi- and many-core…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 Satoshi Tanaka , Kohji Yoshikawa , Takashi Okamoto , Kenji Hasegawa

We present a numerical implementation of radiative transfer based on an explicitly photon-conserving advection scheme, where radiative fluxes over the cell interfaces of a structured or unstructured mesh are calculated with a second-order…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Margarita Petkova , Volker Springel

Non-LTE radiative transfer is a key tool for modern astrophysics: it is the means by which many key synthetic observables are produced, thus connecting simulations and observations. Radiative transfer models also inform our understanding of…

Solar and Stellar Astrophysics · Physics 2025-11-12 Christopher M. J. Osborne , Alexander Sannikov

Learning vector representations for programs is a critical step in applying deep learning techniques for program understanding tasks. Various neural network models are proposed to learn from tree-structured program representations, e.g.,…

Software Engineering · Computer Science 2023-01-10 Wenhan Wang , Kechi Zhang , Ge Li , Shangqing Liu , Anran Li , Zhi Jin , Yang Liu

We present RAYTHEIA, a high-performance reverse ray-tracing algorithm designed to efficiently solve three-dimensional direction-dependent equations in astronomical simulations. The algorithm uses a dual-grid framework in which the native…

Instrumentation and Methods for Astrophysics · Physics 2026-05-12 Zhengping Zhu , Thomas G. Bisbas , Xuefei Tang , Brandt A. L. Gaches , Tianwei Zhang , Huaxi Chen

Our universe is homogeneous and isotropic, and its perturbations obey translation and rotation symmetry. In this work we develop Translation and Rotation Equivariant Normalizing Flow (TRENF), a generative Normalizing Flow (NF) model which…

Cosmology and Nongalactic Astrophysics · Physics 2022-08-03 Biwei Dai , Uros Seljak
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