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  • 1.
    Fritzson, Peter
    et al.
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Aronsson, Peter
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Lundvall, Håkan
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Nyström, Kaj
    Linköping University, Department of Computer and Information Science.
    Pop, Adrian
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Saldamli, Levon
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Broman, David
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    The OpenModelica Modeling, Simulation, and Development Environment2005Conference paper (Refereed)
    Abstract [en]

    Modelica is a modern, strongly typed, declarative, and object-oriented language for modeling and simulation of complex systems. This paper gives a quick overview of some aspects of the OpenModelica environment – an open-source environment for modeling, simulation, and development of Modelica applications. An introduction of the objectives of the environment is given, an overview of the architecture is outlined and a number of examples are illustrated.

  • 2.
    Fritzson, Peter
    et al.
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Engelson, Vadim
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Idebrant, Andreas
    MathCore Engineering AB, Linköping, Sweden.
    Aronsson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Lundvall, Håkan
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Bunus, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Nyström, Kaj
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Modelica - A Strongly Typed System Specification Language for Safe Engineering Practices2004In: Proceedings of the SimSAFE Conference, Karlskoga, Sweden, June 15-17, 2004, 2004Conference paper (Other academic)
    Abstract [en]

    Recent years have witnessed a significant growth of interest in modeling and simulation of engineering application systems. A key factor in this growth has been the development of efficient equation-based simulation languages, with Modelica as one of the prime examples. Such languages have been designed to allow automatic generation of efficient simulation code from declarative specifications. A major objective is to facilitate reuse and exchange of models, model libraries, and simulation specifications.

    The Modelica language and its associated support technologies have achieved considerable success through the development of domain libraries in a number of technical areas. By using domain-libraries complex simulation models can be built by aggregating and combining submodels and components from various physical domains.

    The concept of safe engineering practices has been one of the most important guidelines when designing Modelica. This made it natural to make Modelica a statically strongly typed language, which allows the compiler to check the consistency of a design before it is executed, in contrast to dynamically typed languages such as Matlab.

    The ability of static checking has also influenced the design of conditional equations and the ongoing the design of variant handling features in Modelica. Moreover, the language allows support for standardized physical units, thus enabling tools for unit checking of relationships and connections between interfaces. A third possible level of checking is through design rules within application-specific libraries, which can be enforced via assert statements. These properties taken together gives a good foundation for safe engineering practices, even though more work is needed to further increase the safety quality level.

  • 3.
    Fritzson, Peter
    et al.
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Pop, Adrian Dan Iosif
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Lundvall, Håkan
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Aronsson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Nyström, Kaj
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Saldamli, Levon
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Broman, David
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Sandholm, Anders
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    OpenModelica - A Free Open-Source Environment for System Modeling, Simulation, and Teaching2006In: Proceedings of the2006 IEEE International Conference on Control Applications (CCA)2006 IEEE Conference on Computer-Aided Control Systems Design (CACSD)2006 IEEE International Symposium on Intelligent Control (ISIC), Munich, Germany: IEEE , 2006, p. 1588-1595Conference paper (Refereed)
    Abstract [en]

    Modelica is a modern, strongly typed, declarative, and object-oriented language for modeling and simulation of complex systems. This paper gives a quick overview of some aspects of the OpenModelica environment - an open-source environment for modeling, simulation, and development of Modelica applications. An introduction of the objectives of the environment is given, an overview of the architecture is outlined and a number of examples are illustrated.   

  • 4.
    Lundvall, Håkan
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Automatic Parallelization using Pipelining for Equation-Based Simulation Languages2008Licentiate 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.

    List of papers
    1. Automatic Parallelization of Models using Pipeline Extraction from Combined RHS and Inlined Solvers
    Open this publication in new window or tab >>Automatic Parallelization of Models using Pipeline Extraction from Combined RHS and Inlined Solvers
    2009 (English)In: the 14th Workshop on Compilers for Parallel Computing, 2009Conference paper, Published paper (Other scientific)
    Abstract [en]

    In this work we report preliminary results from a new integrated method of automatically generating parallel code from equationbased object-oriented mathematical models by combining parallelization at two levels of abstraction. Performing inline expansion of a Runge-Kutta solver combined with fine-grained automatic parallelization of the resulting RHS opens up new possibilities for generating high performance code, which is becoming increasingly relevant when multi-core computers are becoming commonplace. We have introduced a new way of scheduling the task graph generated from the simulation problem which utilizes knowledge about locality of the simulation problem and generates a computation pipeline such that processors early in the pipeline can carry on with subsequent time steps while the end of the pipeline still computes the current step. A prototype implementation has been developed as part of the OpenModelica compiler, which has been used for preliminary measurements.

    Keywords
    Modelica, automatic parallelization, equation-based modeling
    Identifiers
    urn:nbn:se:liu:diva-12438 (URN)
    Note
    Submitted, but not yet accepted.Available from: 2008-09-04 Created: 2008-09-04 Last updated: 2013-06-12
    2. Automatic Parallelization of Object Oriented  Models Across Method and System
    Open this publication in new window or tab >>Automatic Parallelization of Object Oriented  Models Across Method and System
    2007 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    In this work we report preliminary results of automatically generating parallel code from equation-based models together at two levels: Performing inline expansion of a Runge-Kutta solver combined with fine-grained automatic parallelization of the resulting RHS opens up new possibilities for generating high performance code, which is becoming increasingly relevant when multi-core computers are becoming common-place.We have introduced a new way of scheduling the task graph generated from the simulation problem which utilizes knowledge about locality of the simulation problem. The scheduling is also done in a way that limits communication, to the greatest extent possible, to neighboring processors thus avoiding expensive global synchronization. Preliminary tests on a PC-cluster show speedup that is better than what was achieved in previous work where parallelization was done only at the equation system level.

    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:liu:diva-12429 (URN)
    Conference
    Proceedings of 6th Eurosim Congress, Ljubjana, Slovenia
    Available from: 2008-09-04 Created: 2008-09-04 Last updated: 2018-01-11
    3. Event Handling in the OpenModelica Compiler and Runtime System
    Open this publication in new window or tab >>Event Handling in the OpenModelica Compiler and Runtime System
    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. p. 21
    Series
    Technical reports in Computer and Information Science, ISSN 1654-7233 ; 2
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12431 (URN)
    Available from: 2008-09-04 Created: 2008-09-04 Last updated: 2014-10-08Bibliographically approved
  • 5.
    Lundvall, Håkan
    et al.
    Linköping University, Department of Computer and Information Science.
    Bunus, Peter
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Towards Automatic Generation of Model Checkable Code from Modelica2004Conference paper (Other academic)
  • 6.
    Lundvall, Håkan
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Automatic Parallelization of Mathematical Models Solved with Inlined Runge-Kutta Solvers2007Conference paper (Other academic)
  • 7.
    Lundvall, Håkan
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Automatic Parallelization of Object Oriented  Models Across Method and System2007Conference paper (Refereed)
    Abstract [en]

    In this work we report preliminary results of automatically generating parallel code from equation-based models together at two levels: Performing inline expansion of a Runge-Kutta solver combined with fine-grained automatic parallelization of the resulting RHS opens up new possibilities for generating high performance code, which is becoming increasingly relevant when multi-core computers are becoming common-place.We have introduced a new way of scheduling the task graph generated from the simulation problem which utilizes knowledge about locality of the simulation problem. The scheduling is also done in a way that limits communication, to the greatest extent possible, to neighboring processors thus avoiding expensive global synchronization. Preliminary tests on a PC-cluster show speedup that is better than what was achieved in previous work where parallelization was done only at the equation system level.

  • 8.
    Lundvall, Håkan
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Automatic Parallelization of Object Oriented Models Executed with Inline Solvers2007Conference paper (Other academic)
  • 9.
    Lundvall, Håkan
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Automatic Parallelization using Pipelining for Equation-Based Simulation Languages2009Conference paper (Refereed)
  • 10.
    Lundvall, Håkan
    et al.
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Event Handling in the OpenModelica Compiler and Run-time System2005Conference paper (Refereed)
    Abstract [en]

    The paper gives an introduction to the problem simulating hybrid DAEs with event-handling using the Modelica language. An implementation in the OpenModelica compiler is presented, and some preliminary results are reported.

  • 11.
    Lundvall, Håkan
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Modelling concurrent activities and resource sharing in Modelica2003Conference paper (Refereed)
  • 12.
    Lundvall, Håkan
    et al.
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Bachmann, Bernhard
    Dept. Mathematics and Engineering, University of Applied Sciences, Bielefeld, Germany.
    Event Handling in the OpenModelica Compiler and Runtime System2008Report (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.

  • 13.
    Lundvall, Håkan
    et al.
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Stavåker, Kristian
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Kessler, Christoph
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Automatic Parallelization of Simulation Code for Equation-based Models with Software Pipelining and Measurements on Three Platforms2008In: Proceedings from the First Swedish Workshop on Multi-Core Computing, MCC-08, November 27-28, 2008, Ronneby, Sweden / [ed] Håkan Grahn, Ronneby, Sweden: Blekinge Institute of Technology , 2008, p. 60-69Conference paper (Refereed)
    Abstract [en]

    In this work we report results from a new integrated method of automatically generating parallel code from Modelica models by combining parallelization at two levels of abstraction. Performing inline expansion of a Runge-Kutta solver combined with fine-grained automatic parallelization of the right-hand side of the resulting equation system opens up new possibilities for generating high performance code, which is becoming increasingly relevant when multi-core computers are becoming commonplace. An implementation, in the form of a backend module for the OpenModelica compiler, has been developed and used for measurements on two architectures: Intel Xeon and SGI Altix 3700 Bx2. This paper also contains some very recent results of a prototype implementation of this parallelization approach on the Cell BE processor architecture.

  • 14.
    Lundvall, Håkan
    et al.
    Linköping University, Department of Computer and Information Science.
    Stavåker, Kristian
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Kessler, Christoph
    Linköping University, Department of Computer and Information Science.
    Automatic Parallelization of Simulation Code for Equation-based Models with Software Pipelining and Measurements on Three Platforms.2008In: SIGARCH Computer Architecture News, ISSN 0163-5964, E-ISSN 1943-5851, Vol. 36, no 5Article in journal (Refereed)
    Abstract [en]

    In this work we report results from a new integrated method of automatically generating parallel code from Modelica models by combining parallelization at two levels of abstraction. Performing inline expansion of a Runge-Kutta solver combined with fine-grained automatic parallelization of the right-hand side of the resulting equation system opens up new possibilities for generating high performance code, which is becoming increasingly relevant when multi-core computers are becoming commonplace. An implementation, in the form of a backend module for the OpenModelica compiler, has been developed and used for measurements on two architectures: Intel Xeon and SGI Altix 3700 Bx2. This paper also contains some very recent results of a prototype implementation of this parallelization approach on the Cell BE processor architecture.

1 - 14 of 14
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