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In many imaging applications where segmented features (e.g. blood vessels) are further used for other numerical simulations (e.g. finite element analysis), the obtained surfaces do not have fine resolutions suitable for the task. Increasing…

Analysis of PDEs · Mathematics 2023-09-19 Yiyao Zhang , Ke Chen , Shang-Hua Yang

Finding an $\epsilon$-stationary point of a nonconvex function with a Lipschitz continuous Hessian is a central problem in optimization. Regularized Newton methods are a classical tool and have been studied extensively, yet they still face…

Optimization and Control · Mathematics 2025-11-03 Yuhao Zhou , Jintao Xu , Bingrui Li , Chenglong Bao , Chao Ding , Jun Zhu

This work uses high-order discontinuous Galerkin discretization techniques as a generic, parameter-free, and reliable tool to accurately predict transitional and turbulent flows through medical devices. Flows through medical devices are…

Fluid Dynamics · Physics 2018-11-19 Niklas Fehn , Wolfgang A. Wall , Martin Kronbichler

With the advent of neoclassically optimised stellarators, optimising stellarators for turbulent transport is an important next step. The reduction of ion-temperature-gradient-driven turbulence has been achieved via shaping of the magnetic…

Plasma Physics · Physics 2015-09-16 J. H. E. Proll , H. E. Mynick , P. Xanthopoulos , S. A. Lazerson , B. J. Faber

As an alternative to solving of Poisson equation in Particle-in-Cell methods, a new construction of current density exactly satisfying continuity equation in finite differences is developed. This procedure called density decomposition is…

Computational Physics · Physics 2007-05-23 Timur Zh. Esirkepov

Stark deceleration enables the production of cold and dense molecular beams with applications in trapping, collisional studies, and precision measurement. Improving the efficiency of Stark deceleration, and hence the achievable molecular…

Chemical Physics · Physics 2020-07-22 David Reens , Hao Wu , Alexander Aeppli , Anna McAuliffe , Piotr Wcisło , Tim Langen , Jun Ye

We present a novel method for minimizing the effects of radiative depolarization in electron storage rings by use of vertical orbit bumps in the arcs. Electron polarization is directly characterized by the RMS of the so-called spin orbit…

Accelerator Physics · Physics 2024-03-05 Matthew G. Signorelli , Yunhai Cai , Georg H. Hoffstaetter de Torquat

Resolving numerically Vlasov-Poisson equations for initially cold systems can be reduced to following the evolution of a three-dimensional sheet evolving in six-dimensional phase-space. We describe a public parallel numerical algorithm…

Computational Physics · Physics 2016-06-29 Thierry Sousbie , Stéphane Colombi

Inversions of rotational splittings have shown that there exists at the base of the solar convection zone a region called the tachocline in which high radial gradients of the rotation rate occur. The usual linear regularization methods tend…

Astrophysics · Physics 2007-05-23 T. Corbard , L. Blanc-Feraud , G. Berthomieu , J. Provost

We present recent improvements in the simulation of regolith sampling processes in microgravity using the numerical particle method smooth particle hydrodynamics (SPH). We use an elastic-plastic soil constitutive model for large deformation…

Earth and Planetary Astrophysics · Physics 2017-05-24 Christoph M. Schäfer , Samuel Scherrer , Robert Buchwald , Thomas I. Maindl , Roland Speith , Wilhelm Kley

The capacitance of capacitive energy storage devices can not be directly measured, but can be estimated from the input and output signals expressed in the time or frequency domains. Here the time-domain voltage-charge relationship in…

Applied Physics · Physics 2023-03-08 Anis Allagui , Ahmed Elwakil

The Ryabinkin-Kohut-Staroverov (RKS) and Kanungo-Zimmerman-Gavini (KZG) methods offer two approaches to find exchange-correlation (XC) potentials from ground state densities. The RKS method utilizes the one- and two-particle reduced density…

Chemical Physics · Physics 2024-08-06 Bikash Kanungo , Soumi Tribedi , Paul M. Zimmerman , Vikram Gavini

Single Helical Axis (SHAx) configurations are emerging as the natural state for high current reversed field pinch (RFP) plasmas. These states feature the presence of transport barriers in the core plasma. Here we present a method for…

One aim of dimensionality reduction is to discover the main factors that explain the data, and as such is paramount to many applications. When working with high dimensional data, autoencoders offer a simple yet effective approach to learn…

Machine Learning · Computer Science 2025-08-29 Benjamin Couéraud , Vikram Sunkara , Christof Schütte

Stencil computation is one of the most important kernels in various scientific and engineering applications. A variety of work has focused on vectorization techniques, aiming at exploiting the in-core data parallelism. Briefly, they either…

Distributed, Parallel, and Cluster Computing · Computer Science 2021-03-18 Kun Li , Liang Yuan , Yunquan Zhang , Yue Yue , Hang Cao , Pengqi Lu

In this work we consider the problem of optimizing a stellarator subject to hard constraints on the design variables and physics properties of the equilibrium. We survey current numerical methods for handling these constraints, and…

Plasma Physics · Physics 2024-11-20 Rory Conlin , Patrick Kim , Daniel W. Dudt , Dario Panici , Egemen Kolemen

'Coil design' is an inverse problem in which arrangements of wire are designed to generate a prescribed magnetic field when energized with electric current. The design of gradient and shim coils for magnetic resonance imaging (MRI) are…

Classical Physics · Physics 2010-02-19 Michael Poole , Pierre Weiss , Hector Sanchez Lopez , Michael Ng , Stuart Crozier

We consider a class of nonconvex nonsmooth multicomposite optimization problems where the objective function consists of a Tikhonov regularizer and a composition of multiple nonconvex nonsmooth component functions. Such optimization…

Optimization and Control · Mathematics 2026-03-13 Lingzi Jin , Xiao Wang , Xiaojun Chen

Weighted compact nonlinear schemes (WCNS) [Deng and Zhang, JCP 165(2000): 22-44] were developed to improve the performance of the compact high-order nonlinear schemes (CNS) by utilizing the weighting technique originally designed for WENO…

Computational Physics · Physics 2020-11-30 Huaibao Zhang , Fan Zhang , Chunguang Xu

We have developed a novel Monte Carlo method for simulating the dynamical evolution of stellar systems in arbitrary geometry. The orbits of stars are followed in a smooth potential represented by a basis-set expansion and perturbed after…

Astrophysics of Galaxies · Physics 2014-12-04 Eugene Vasiliev