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This paper is devoted to the investigation of inverse problems related to stationary drift-diffusion equations modeling semiconductor devices. In this context we analyze several identification problems corresponding to different types of…

Analysis of PDEs · Mathematics 2020-11-24 M. Burger , H. W. Engl , A. Leitão , P. A. Markowich

We propose Diffusion-Sharpening, a fine-tuning approach that enhances downstream alignment by optimizing sampling trajectories. Existing RL-based fine-tuning methods focus on single training timesteps and neglect trajectory-level alignment,…

Computer Vision and Pattern Recognition · Computer Science 2025-02-18 Ye Tian , Ling Yang , Xinchen Zhang , Yunhai Tong , Mengdi Wang , Bin Cui

In mathematical finance a popular approach for pricing options under some Levy model is to consider underlying that follows a Poisson jump diffusion process. As it is well known this results in a partial integro-differential equation (PIDE)…

Computational Finance · Quantitative Finance 2010-02-11 Andrey Itkin , Peter Carr

Major drawback of studying diffusion in multi-component systems is the lack of suitable techniques to estimate the diffusion parameters. In this study, a generalized treatment to determine the intrinsic diffusion coefficients in…

Materials Science · Physics 2022-08-23 Sangeeta Santra , Aloke Paul

Diffusion model-based inverse problem solvers have demonstrated state-of-the-art performance in cases where the forward operator is known (i.e. non-blind). However, the applicability of the method to blind inverse problems has yet to be…

Computer Vision and Pattern Recognition · Computer Science 2022-11-22 Hyungjin Chung , Jeongsol Kim , Sehui Kim , Jong Chul Ye

We introduce a \textit{non-modal} analysis technique that characterizes the diffusion properties of spectral element methods for linear convection-diffusion systems. While strictly speaking only valid for linear problems, the analysis is…

Computational Physics · Physics 2019-01-30 Pablo Fernandez , Rodrigo Moura , Gianmarco Mengaldo , Jaime Peraire

Modeling metasurfaces with high accuracy and efficiency is challenging because they have features smaller than the wavelength but sizes much larger than the wavelength. Full wave simulation is accurate but very slow. Popular design…

Optics · Physics 2023-04-04 Zhicheng Wu , Xiaoyan Huang , Nanfang Yu , Zongfu Yu

When analyzing cell trajectories, we often have to deal with noisy data due to the random motion of the cells and possible imperfections in cell center detection. To smooth these trajectories, we present a mathematical model and numerical…

Numerical Analysis · Mathematics 2023-04-04 Giulia Lupi , Karol Mikula , Seol Ah Park

Convexity splitting like schemes with improved accuracy are proposed for a phase field model for surface diffusion. The schemes are developed to enable large scale simulations in three spatial dimensions describing experimentally observed…

Numerical Analysis · Mathematics 2019-11-04 Rainer Backofen , Steven M. Wise , Marco Salvalaglio , Axel Voigt

In his monograph Chebyshev and Fourier Spectral Methods, John Boyd claimed that, regarding Fourier spectral methods for solving differential equations, ``[t]he virtues of the Fast Fourier Transform will continue to improve as the relentless…

Numerical Analysis · Mathematics 2023-02-03 Craig Gross , Mark Iwen

This paper investigates the numerical modeling of a time-dependent heat transmission problem by the convolution quadrature boundary element method. It introduces the latest theoretical development into the error analysis of the numerical…

Numerical Analysis · Mathematics 2017-11-08 Tianyu Qiu , Alexander Rieder , Francisco-Javier Sayas , Shougui Zhang

We develop a helioseismic inversion algorithm that can be used to recover sub-surface vertical profiles of 2-dimensional supergranular flows from surface measurements of synthetic wave travel times. We carry out seismic wave-propagation…

Solar and Stellar Astrophysics · Physics 2017-11-29 Jishnu Bhattacharya , Shravan M. Hanasoge , Aaron C. Birch , Laurent Gizon

In this work, a new collocation approach using a combination of a wavelet operational matrix method and the exponential spline interpolation is proposed to solve the time-fractional convection-diffusion equation with variable coefficients.…

Numerical Analysis · Mathematics 2016-09-27 Xiaogang Zhu , Yufeng Nie

Preliminary mission design requires an efficient and accurate approximation to the low-thrust rendezvous trajectories, which might be generally three-dimensional and involve multiple revolutions. In this paper, a new shaping method using…

Robotics · Computer Science 2022-03-02 Di Wu , Tongxin Zhang , Yuan Zhong , Fanghua Jiang , Junfeng Li

Trajectory optimization of low-thrust perturbed orbit rendezvous is a crucial technology for space missions in low Earth orbits, which is difficult to solve due to its initial value sensitivity, especially when the transfer trajectory has…

Instrumentation and Methods for Astrophysics · Physics 2023-05-03 An-yi Huang , Heng-nian Li

We consider the construction of semi-implicit linear multistep methods which can be applied to time dependent PDEs where the separation of scales in additive form, typically used in implicit-explicit (IMEX) methods, is not possible. As…

Numerical Analysis · Mathematics 2020-01-14 Giacomo Albi , Lorenzo Pareschi

In this paper, we propose stochastic structure-preserving schemes to compute the effective diffusivity for particles moving in random flows. We first introduce the motion of particles using the Lagrangian formulation, which is modeled by…

Numerical Analysis · Mathematics 2020-08-24 Junlong Lyu , Zhongjian Wang , Jack Xin , Zhiwen Zhang

In this paper, we present a theoretical and computational workflow for the non-parametric Bayesian inference of drift and diffusion functions of autonomous diffusion processes. We base the inference on the partial differential equations…

Computational Engineering, Finance, and Science · Computer Science 2024-11-05 Maximilian Kruse , Sebastian Krumscheid

We propose a new data analysis approach for the efficient post-processing of bundles of finite element data from numerical simulations. The approach is based on the mathematical principles of symmetry. We consider the case where simulations…

Numerical Analysis · Mathematics 2019-05-23 Rodrigo Iza-Teran , Jochen Garcke

Solving large-scale Generalized Eigenvalue Problems (GEPs) is a fundamental yet computationally prohibitive task in science and engineering. As a promising direction, contour integral (CI) methods, such as the CIRR algorithm, offer an…

Machine Learning · Computer Science 2025-11-05 Yeqiu Chen , Ziyan Liu , Hong Wang