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Event Handling in the OpenModelica Compiler and Runtime System
Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.ORCID iD: 0000-0002-3435-4996
Dept. Mathematics and Engineering, University of Applied Sciences, Bielefeld, Germany.
2008 (English)Report (Other academic)
Abstract [en]

This paper gives an introduction and overview of problems and solutions regarding simulating hybrid DAEs (systems of Differential Algebraic Equations) with event-handling, in the context of producing such equations from models in the Modelica language. Iimplementation and measurements are done in the OpenModelica environment. The basic hybrid DAE solution algorithm is presented, followed by a discussion of handling possibly varying structure of the active part of the hybrid DAE, and how to find consistent initial values at start or restart of simulation. The problem of detecting events during continuous-time simulation is dealt with using crossing functions and an algorithm for proper integration with a numerical solver, here DASRT. Event-related aspects of code generation from models are presented, followed by an example showing how the event mechanism works. Finally, preliminary results from translating and simulating two examples models, the bouncing ball and the full wave rectifier, are presented and compared with those from a commercial simulation tool (Dymola), giving identical results.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2008. , 21 p.
Series
Technical reports in Computer and Information Science, ISSN 1654-7233 ; 2
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-12431OAI: oai:DiVA.org:liu-12431DiVA: diva2:67
Available from: 2008-09-04 Created: 2008-09-04 Last updated: 2014-10-08Bibliographically approved
In thesis
1. Automatic Parallelization using Pipelining for Equation-Based Simulation Languages
Open this publication in new window or tab >>Automatic Parallelization using Pipelining for Equation-Based Simulation Languages
2008 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

During the most recent decades modern equation-based object-oriented modeling and simulation languages, such as Modelica, have become available. This has made it easier to build complex and more detailed models for use in simulation. To be able to simulate such large and complex systems it is sometimes not enough to rely on the ability of a compiler to optimize the simulation code and reduce the size of the underlying set of equations to speed up the simulation on a single processor. Instead we must look for ways to utilize the increasing number of processing units available in modern computers. However to gain any increased performance from a parallel computer the simulation program must be expressed in a way that exposes the potential parallelism to the computer. Doing this manually is not a simple task and most modelers are not experts in parallel computing. Therefore it is very appealing to let the compiler parallelize the simulation code automatically. This thesis investigates techniques of using automatic translation of models in typical equation based languages, such as Modelica, into parallel simulation code that enable high utilization of available processors in a parallel computer. The two main ideas investigated here are the following: first, to apply parallelization simultaneously to both the system equations and the numerical solver, and secondly. to use software pipelining to further reduce the time processors are kept waiting for the results of other processors. Prototype implementations of the investigated techniques have been developed as a part of the OpenModelica open source compiler for Modelica. The prototype has been used to evaluate the parallelization techniques by measuring the execution time of test models on a few parallel archtectures and to compare the results to sequential code as well as to the results achieved in earlier work. A measured speedup of 6.1 on eight processors on a shared memory machine has been reached. It still remains to evaluate the methods for a wider range of test models and parallel architectures.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2008. 25 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1381
Keyword
Equation-Based languages, automatic parallelization, Modelica, simulation, Ekvationsbaserade språk, automatisk parallellisering, Modelica, simulering
National Category
Computer Science
Identifiers
urn:nbn:se:liu:diva-12504 (URN)LIU-TEK-LIC-2008:39 (Local ID)978-91-7393-799-3 (ISBN)LIU-TEK-LIC-2008:39 (Archive number)LIU-TEK-LIC-2008:39 (OAI)
Presentation
2008-09-26, Alan Turing, Hus E, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2008-09-09 Created: 2008-09-09 Last updated: 2014-10-08Bibliographically approved

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Event Handling in the OpenModelica Compiler and Runtime System(260 kB)1412 downloads
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Lundvall, HåkanFritzson, Peter

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