134,779 research outputs found
The Astrophysical Multipurpose Software Environment
We present the open source Astrophysical Multi-purpose Software Environment
(AMUSE, www.amusecode.org), a component library for performing astrophysical
simulations involving different physical domains and scales. It couples
existing codes within a Python framework based on a communication layer using
MPI. The interfaces are standardized for each domain and their implementation
based on MPI guarantees that the whole framework is well-suited for distributed
computation. It includes facilities for unit handling and data storage.
Currently it includes codes for gravitational dynamics, stellar evolution,
hydrodynamics and radiative transfer. Within each domain the interfaces to the
codes are as similar as possible. We describe the design and implementation of
AMUSE, as well as the main components and community codes currently supported
and we discuss the code interactions facilitated by the framework.
Additionally, we demonstrate how AMUSE can be used to resolve complex
astrophysical problems by presenting example applications.Comment: 23 pages, 25 figures, accepted for A&
COORDINATION OF LEADER-FOLLOWER MULTI-AGENT SYSTEM WITH TIME-VARYING OBJECTIVE FUNCTION
This thesis aims to introduce a new framework for the distributed control of multi-agent systems with adjustable swarm control objectives. Our goal is twofold: 1) to provide an overview to how time-varying objectives in the control of autonomous systems may be applied to the distributed control of multi-agent systems with variable autonomy level, and 2) to introduce a framework to incorporate the proposed concept to fundamental swarm behaviors such as aggregation and leader tracking. Leader-follower multi-agent systems are considered in this study, and a general form of time-dependent artificial potential function is proposed to describe the varying objectives of the system in the case of complete information exchange. Using Lyapunov methods, the stability and boundedness of the agents\u27 trajectories under single order and higher order dynamics are analyzed. Illustrative numerical simulations are presented to demonstrate the validity of our results. Then, we extend these results for multi-agent systems with limited information exchange and switching communication topology. The first steps of the realization of an experimental framework have been made with the ultimate goal of verifying the simulation results in practice
Predicting the statistics of wave transport through chaotic cavities by the Random Coupling Model: a review and recent progress
In this review, a model (the Random Coupling Model) that gives a statistical
description of the coupling of radiation into and out of large enclosures
through localized and/or distributed channels is presented. The Random Coupling
Model combines both deterministic and statistical phenomena. The model makes
use of wave chaos theory to extend the classical modal description of the
cavity fields in the presence of boundaries that lead to chaotic ray
trajectories. The model is based on a clear separation between the universal
statistical behavior of the isolated chaotic system, and the deterministic
coupling channel characteristics. Moreover, the ability of the random coupling
model to describe interconnected cavities, aperture coupling, and the effects
of short ray trajectories is discussed. A relation between the random coupling
model and other formulations adopted in acoustics, optics, and statistical
electromagnetics, is examined. In particular, a rigorous analogy of the random
coupling model with the Statistical Energy Analysis used in acoustics is
presented.Comment: 32 pages, 9 figures, submitted to 'Wave Motion', special issue
'Innovations in Wave Model
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