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Related papers: Photon (Non)Conservation in the Reduced Speed of L…

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I show that the Reduced Speed of Light (RSL) approximation, when used properly (i.e. as originally designed - only for the local sources but not for the cosmic background), remains a highly accurate numerical method for modeling cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-14 Nickolay Y. Gnedin

The reduced speed of light approximation (RSLA) has been employed to speed up radiative transfer simulations of reionization by a factor of $\gtrsim 5-10$. However, it has been shown to cause significant errors in the HI-ionizing background…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-20 Christopher Cain

The reduced speed of light approximation is used in a variety of simulations of the epoch of reionization and galaxy formation. Its popularity stems from its ability to drastically reduce the computing cost of a simulation, by allowing the…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-19 P. Ocvirk , D. Aubert , J. Chardin , N. Deparis , J. Lewis

Coupled radiative-hydrodynamics simulations of the epoch of reionization aim to reproduce the propagation of ionization fronts during the transition before the overlap of HII regions. Many of these simulations use moment-based methods to…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-13 Nicolas Deparis , Dominique Aubert , Pierre Ocvirk , Jonathan Chardin , Joseph Lewis

Quantum speed limit (QSL) under noise has drawn considerable attention in real quantum computational processes and quantum communication. Though non-Markovian noise is proven to be able to accelerate quantum evolution for a damped…

Quantum Physics · Physics 2014-03-18 Z. Y. Xu , S. Q. Zhu

The radiation transport problem in the plane-parallel medium with the large velocity gradient is considered. The Sobolev approximation is used. The effects of continuum absorption and line overlap are taken into account. The photon loss…

Astrophysics of Galaxies · Physics 2021-02-03 Aleksandr Nesterenok

Non-line-of-sight (NLOS) imaging seeks to reconstruct hidden objects by analyzing reflections from intermediary surfaces. Existing methods typically model both the measurement data and the hidden scene in three dimensions, overlooking the…

Computer Vision and Pattern Recognition · Computer Science 2025-08-05 Yijun Wei , Jianyu Wang , Leping Xiao , Zuoqiang Shi , Xing Fu , Lingyun Qiu

We present a novel, easy-to-use method based on the photon-mapping technique to simulate photometric images of moving targets. Realistic images can be created in two passes: photon tracing and image rendering. The nature of light sources,…

Instrumentation and Methods for Astrophysics · Physics 2021-10-13 Junju Du , Shaoming Hu , Xu Chen , Hai Cao , Yuchen Jiang

Boson sampling is a well-defined task that is strongly believed to be intractable for classical computers, but can be efficiently solved by a specific quantum simulator. However, an outstanding problem for large-scale experimental boson…

It is demonstrated that non-constant kernel solution, that can fit the spatial variations of the kernel can be obtained with minimum computing time. The CPU cost required with this new extension of the image subtraction method is almost the…

Astrophysics · Physics 2007-05-23 C. Alard

A reduced-speed-of-light (RSOL) approximation is a useful technique for magnetohydrodynamic (MHD)-particle-in-cell (PIC) simulations. With a RSOL, some "in-code" speed-of-light $\tilde{c}$ is set to much lower values than the true $c$,…

High Energy Astrophysical Phenomena · Physics 2022-09-20 Suoqing Ji , Philip F. Hopkins

Many astrophysical phenomena exhibit relativistic radiative flows. While velocities in excess of $v \sim 0.1c$ can occur in these systems, it has been common practice to approximate radiative transfer to $\cO(v/c)$. In the case of neutrino…

Astrophysics · Physics 2007-05-23 Christian Y. Cardall , Eric J. Lentz , Anthony Mezzacappa

The excursion set reionization framework is widely used, due to its speed and accuracy in reproducing the 3D topology of reionization. However, it is known that it does not conserve photon number. Here, we introduce an efficient, on-the-fly…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-05 Jaehong Park , Bradley Greig , Andrei Mesinger

Recently it has been shown that precise dose control and an increase in the overall acquisition speed of atomic resolution scanning transmission electron microscope (STEM) images can be achieved by acquiring only a small fraction of the…

We present a fast and simple technique to convert images into a radiance surface-based scene representation. Building on existing radiance volume reconstruction algorithms, we introduce a subtle yet impactful modification of the loss…

Photons are elementary particles of light in quantum mechanics, whose dynamics can be difficult to gain detailed insights, especially in complex systems. Simulation is a promising tool to resolve this issue, but it must address the curse of…

Quantum Physics · Physics 2024-02-21 Junpei Oba , Seiji Kajita , Akihito Soeda

Images taken in a low light condition with the presence of camera shake suffer from motion blur and photon shot noise. While state-of-the-art image restoration networks show promising results, they are largely limited to well-illuminated…

Image and Video Processing · Electrical Eng. & Systems 2023-04-07 Yash Sanghvi , Zhiyuan Mao , Stanley H. Chan

The Varying Speed of Light (VSL) model describes how the speed of light in a vacuum changes with cosmological redshift. Despite numerous models, there is little observational evidence for this variation. While the speed of light can be…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-06 Cheng-Yu Zhang , Wei Hong , Yu-Chen Wang , Tong-Jie Zhang

We show that numerical simulations of reionization that resolve the Lyman Limit systems (and, thus, correctly count absorptions of ionizing photons) have converged to about 10% level for 5<z<6.2 and are in reasonable agreement (within 10%)…

Astrophysics · Physics 2010-11-11 Nickolay Y. Gnedin , Xiaohui Fan

Most image super-resolution (SR) methods are developed on synthetic low-resolution (LR) and high-resolution (HR) image pairs that are constructed by a predetermined operation, e.g., bicubic downsampling. As existing methods typically learn…

Image and Video Processing · Electrical Eng. & Systems 2021-09-09 Sanghyun Son , Jaeha Kim , Wei-Sheng Lai , Ming-Husan Yang , Kyoung Mu Lee
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