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Inertia
About: Inertia is a research topic. Over the lifetime, 12006 publications have been published within this topic receiving 164291 citations.
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TL;DR: In this article, the authors compare three approaches to increase the critical time step: micro-inertia formulations from continuum mechanics, inertia penalties which are used in computational mechanics, and mass scaling techniques that are mainly used in structural dynamics.
Abstract: Explicit time integration is a popular method to simulate the dynamical behaviour of a system. Unfortunately, explicit time integration is only conditionally stable: the time step must be chosen not larger than the so-called "critical time step", otherwise the numerical solution may become unstable. To reduce the CPU time needed to carry out simulations, it is desirable to explore methods that increase the critical time step, which is the main objective of our paper. To do this, first we discuss and compare three approaches to increase the critical time step: micro-inertia formulations from continuum mechanics, inertia penalties which are used in computational mechanics, and mass scaling techniques that are mainly used in structural dynamics. As it turns out, the similarities between these methods are significant, and in fact they are identical in 1D if linear finite elements are used. This facilitates interpretation of the additional parameters in the various methods. Next, we derive, for a few simple finite element types, closed-form expressions for the critical time step with micro-structural magnification factors. Finally, we discuss computational overheads and some implementational details.
39 citations
39 citations
TL;DR: An Inertia Calculation Application (ICA), which could be implemented as part of a Wide Area Monitoring Protection and Control scheme, is presented and has been validated by using computer simulations, under laboratory conditions and by using real-life data recorded by a transmission system operator.
39 citations
01 Jan 1995
TL;DR: Einstein Geometrodynamics and Inertia: The Initial-Value Problem in Einstein Geometroynamics as discussed by the authors and the Gravitomagnetic Field and its Measurement.
Abstract: PrefaceChart of Main Topics1A First Tour12Einstein Geometrodynamics133Tests of Einstein Geometrodynamics874Cosmology, Standard Models, and Homogeneous Rotating Models1855The Initial-Value Problem in Einstein Geometrodynamics2696The Gravitomagnetic Field and Its Measurement3157Some Highlights of the Past and a Summary of Geometrodynamics and Inertia384Mathematical Appendix403Symbols and Notations437Author Index445Subject Index of Mathematical Appendix455Subject Index461Fundamental and Astronomical Constants and Units493
39 citations
11 Dec 2006
TL;DR: In this paper, the authors describe a novel identification technique of the moment of inertia and the viscous friction coefficient for a servo drive system based on the basic dynamic equation of a mechanical system, and it uses the torque reference of a speed controller and actual rotating speed of machine for the identification.
Abstract: This paper describes a novel identification technique of the moment of inertia and the viscous friction coefficient for a servo drive system. It is developed based on the basic dynamic equation of a mechanical system, and it uses the torque reference of a speed controller and the actual rotating speed of machine for the identification. Regardless of the simplicity of the techniques it is robust to external disturbances such as measurement noise, coulomb friction, mechanical resonance of the drive system. The identified inertia and friction can be used for auto-tuning of the gains in the speed controller and the disturbance observer. The effectiveness of the proposed method is proved by the computer simulation and experimental results.
39 citations