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Recently, our group developed explicit symplectic methods for curved spacetimes that are not split into several explicitly integrable parts, but are via appropriate time transformations. Such time-transformed explicit symplectic integrators…

General Relativity and Quantum Cosmology · Physics 2024-12-05 Xin Wu , Ying Wang , Wei Sun , Fuyao Liu , Dazhu Ma

Implicit solvers present strong limitations when used on supercomputing facilities and in particular for adaptive mesh-refinement codes. We present a new method for implicit adaptive time-stepping on adaptive mesh refinement-grids. We…

Instrumentation and Methods for Astrophysics · Physics 2014-03-05 Benoit Commercon , Vincent Debout , Romain Teyssier

We propose a novel time stepping method for linear poroelasticity by extending a recent iterative decoupling approach to the second-order case. This results in a two-step scheme with an inner iteration and a relaxation step. We prove…

Numerical Analysis · Mathematics 2025-08-20 R. Altmann , M. Deiml

Dynamic simulation plays a crucial role in power system transient stability analysis, but traditional numerical integration-based methods are time-consuming due to the small time step sizes. Other semi-analytical solution methods, such as…

Systems and Control · Electrical Eng. & Systems 2025-03-14 Kaiyang Huang , Yang Liu , Kai Sun , Feng Qiu

Over the past few years, robotics simulators have largely improved in efficiency and scalability, enabling them to generate years of simulated data in a few hours. Yet, efficiently and accurately computing the simulation derivatives remains…

Robotics · Computer Science 2025-05-21 Quentin Le Lidec , Louis Montaut , Yann de Mont-Marin , Fabian Schramm , Justin Carpentier

Several integration schemes exits to solve the equations of motion of the $N$-body problem. The Lie-integration method is based on the idea to solve ordinary differential equations with Lie-series. In the 1980s this method was applied for…

Astrophysics · Physics 2009-11-13 Andras Pal , Aron Suli

The two-dimensional n-body problem of classical mechanics is a non-integrable Hamiltonian system for n > 2. Traditional numerical integration algorithms, which are polynomials in the time step, typically lead to systematic drifts in the…

Computational Physics · Physics 2009-11-07 Oksana Kotovych , John C. Bowman

Many recently introduced enhanced sampling techniques are based on biasing coarse descriptors (collective variables) of a molecular system on the fly. Sometimes the calculation of such collective variables is expensive and becomes a…

Computational Physics · Physics 2015-09-01 Marco Jacopo Ferrarotti , Sandro Bottaro , Andrea Pérez-Villa , Giovanni Bussi

A key ingredient to achieving intelligent behavior is physical understanding that equips robots with the ability to reason about the effects of their actions in a dynamic environment. Several methods have been proposed to learn dynamics…

Robotics · Computer Science 2020-01-24 David Millard , Eric Heiden , Shubham Agrawal , Gaurav S. Sukhatme

This paper considers an optimization problem for a dynamical system whose evolution depends on a collection of binary decision variables. We develop scalable approximation algorithms with provable suboptimality bounds to provide…

Optimization and Control · Mathematics 2016-10-31 Insoon Yang , Samuel A. Burden , Ram Rajagopal , S. Shankar Sastry , Claire J. Tomlin

Stellarators are a promising route to steady-state fusion power. However, to achieve the required confinement, the magnetic geometry must be highly optimized. This optimization requires navigating high-dimensional spaces, often…

Plasma Physics · Physics 2019-09-25 Elizabeth Paul , Ian Abel , Matt Landreman , William Dorland

We present new splitting methods designed for the numerical integration of near-integrable Hamiltonian systems, and in particular for planetary N-body problems, when one is interested in very accurate results over a large time span. We…

Numerical Analysis · Mathematics 2015-04-10 Sergio Blanes , Fernando Casas , Ariadna Farres , Jacques Laskar , Joseba Makazaga , Ander Murua

Selecting an effective step-size is a fundamental challenge in first-order optimization, especially for problems with non-Euclidean geometries. This paper presents a novel adaptive step-size strategy for optimization algorithms that rely on…

Optimization and Control · Mathematics 2025-10-14 Abbas Khademi , Antonio Silveti-Falls

External effects such as shocks and temperature variations affect the calibration of visual-inertial sensor systems and thus they cannot fully rely on factory calibrations. Re-calibrations performed on short user-collected datasets might…

Robotics · Computer Science 2019-01-23 Thomas Schneider , Mingyang Li , Cesar Cadena , Juan Nieto , Roland Siegwart

This paper presents an algorithm that finds a centroidal motion and footstep plan for a Spring-Loaded Inverted Pendulum (SLIP)-like bipedal robot model substantially faster than real-time. This is achieved with a novel representation of the…

Robotics · Computer Science 2024-09-17 Tara Bartlett , Ian R. Manchester

In this paper we address the challenging problem of designing globally convergent estimators for the parameters of nonlinear systems containing a non-separable exponential nonlinearity. This class of terms appears in many practical…

Dynamical Systems · Mathematics 2022-11-17 Romeo Ortega , Alexey Bobtsov , Ramon Costa-Castello , Nikolay Nikolaev

The three-step alternating iteration scheme for finding an iterative solution of a singular (non-singular) linear systems in a faster way was introduced by Nandi {\it et al.} [Numer. Algorithms; 84 (2) (2020) 457-483], recently. The authors…

Numerical Analysis · Mathematics 2023-05-09 Vaibhav Shekhar , Punit Sharma

The core of every orbit determination process is the comparison between the measured observables and their predicted values, computed using the adopted mathematical models, and the minimization, in a least square sense, of their…

Instrumentation and Methods for Astrophysics · Physics 2019-08-22 Marco Zannoni , Paolo Tortora

One of the fundamental aspects of statistical behaviour in many-body systems is exponential divergence of neighbouring orbits, which is often discussed in terms of Liapounov exponents. Here we study this topic for the classical…

Astrophysics · Physics 2015-06-24 P. Hut , D. C. Heggie

We present a strategy for selecting the values of elasticity parameters by comparing walk-away vertical seismic profiling data with a multilayered model in the context of Bayesian Information Criterion. We consider $P$-wave traveltimes and…