| 1. |
- Andersson, Anders, 1983-, et al.
(författare)
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Models for Distributed Real-Time Simulation in a Vehicle Co-Simulator Setup
- 2013
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Ingår i: Proceedings of the 5th International Workshop on Equation-Based Object-Oriented Modeling Languages and Tools. - Linköping : Linköping University Electronic Press. - 9789175196176 - 9789175196213 ; , s. 131-139
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Konferensbidrag (refereegranskat)abstract
- A car model in Modelica has been developed to be used in a new setup for distributed real-time simulation where a moving base car simulator is connected with a real car in a chassis dynamometer via a 500m fiber optic communication link. The new co-simulator set-up can be used in a number of configurations where hardware in the loop can be interchanged with software in the loop. The models presented in this paper are the basic blocks chosen for modeling the system in the context of a distributed real-time simulation, estimating parameters for the powertrain model, the choice of numeric solver, and the interaction with the solver for real-time properties.
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| 2. |
- Andersson, Niclas, et al.
(författare)
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Comparative Evaluation and Industrial Application of Code Generator Generators
- 1992
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The past ten to fifteen years has seen active research in the area of automatically generating the code generator part of compilers from formal specifications. However, less work has been done on evaluating and applying these systems in an industrial setting. This paper attempts to fill this gap.Three systems for automatic generation of code generators are evaluated in this paper: CGSS, BEG and TWIG. CGSS is an older Graham-Glanville style system based on pattern matching through parsing, whereas BEG and TWIG are more recent systems based on tree pattern matching combined with dynamic programming. An industrial-strength code generator previously implemented for a special-purpose language using the CGSS system is described and compared in some detail to our new implementation based on the BEG system. Several problems of integrating local and global register allocation within automatically generated code generators are described, and some solutions proposed. We finally conclude that current technology of automatically generating code generators is viable in an industrial setting. However, further research needs to be done on the problem of properly integrating register allocation with instruction selection, when both are generated from declarative specifications.
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| 3. |
- Andersson, Niclas, et al.
(författare)
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Generating Parallel Code from Object Oriented Mathematical Models
- 1995
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Ingår i: PPOPP 1995. - New York, NY, USA : ACM. - 0897917006 ; , s. 48-57
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Konferensbidrag (refereegranskat)abstract
- For a long time efficient use of parallel computers has been hindered by dependencies introduced in software through low-level implementation practice. In this paper we present a programming environment and language called Object-Math (Object oriented Mathematical language for scientific computing), which aims at eliminating this problem by allowing the user to represent mathematical equation-based models directly in the system. The system performs analysis of mathematical models to extract parallelism and automatically generates parallel code for numerical solution.In the context of industrial applications in mechanical analysis, we have so far primarily explored generation of parallel code for solving systems of ordinary differential equations (ODEs), in addition to preliminary work on generating code for solving partial differential equations. Two approaches to extracting parallelism have been implemented and evaluated: extracting parallelism at the equation system level and at the single equation level, respectively. We found that for several applications the corresponding systems of equations do not partition well into subsystems. This means that the equation system level approach is of restricted general applicability. Thus, we focused on the equation-level approach which yielded significant parallelism for ODE systems solution. For the bearing simulation applications we present here, the achieved speedup is however critically dependent on low communication latency of the parallel computer.
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| 4. |
- Aronsson, Peter, et al.
(författare)
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A Task Merging Technique for Parallelization of Modelica Models
- 2005
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Ingår i: 4th International Modelica Conference. ; , s. -128
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Konferensbidrag (refereegranskat)abstract
- This paper presents improvements on techniques of merging tasks in task graphs generated in the ModPar automatic parallelization module of the OpenModelica compiler. Automatic parallelization is performed on Modelica models by building data dependency graphs called task graphs from the model equations. To handle large task graphs with fine granularity, i.e. low ratio of execution and communication cost, the tasks are merged. This is done by using a graph rewrite system(GRS), which is a set of graph transformation rules applied on the task graph. In this paper we have solved the confluence problem of the task merging system by giving priorities to the merge rules. A GRS is confluent if the application order of the graph transformations does not matter, i.e. the same result is gained regardless of application order. We also present a Modelica model suited for automatic parallelization and show results on this using the ModPar module in the OpenModelica compiler.
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| 7. |
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| 8. |
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| 9. |
- Aronsson, Peter, et al.
(författare)
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Parallel Code Generation in MathModelica / An Object Oriented Component Based Simulation Environment
- 2001
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Ingår i: Proceedings of Workshop on Parallel/High Performance Object-Oriented Scientific Computing (POOSC’01).
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Konferensbidrag (refereegranskat)abstract
- Modelica is an a-causal, equation based, object oriented modeling lan- guage for modeling and efficient simulation of large and complex multi domain systems. The Modelica language, with its strong software component model, makes it possible to use visual component programming, where large complex physical systems can be modeled and composed in a graphical way. One tool with support for both graphical modeling, textual programming and simulation is MathModelica. To deal with growing complexity of modeled systems in the Modelica language, the need for parallelization becomes increasingly important in order to keep sim- ulation time within reasonable limits. The first step in Modelica compilation results in an Ordinary Differential Equa- tion system or a Differential Algebraic Equation system, depending on the spe- cific Modelica model. The Modelica compiler typically performs optimizations on this system of equations to reduce its size. The optimized code consists of simple arithmetic operations, assignments, and function calls. This paper presents an automatic parallelization tool that builds a task graph from the optimized sequential code produced by a commercial Modelica compiler. Var- ious scheduling algorithms have been implemented, as well as specific enhance- ments to cluster nodes for better computation/communication tradeoff. Finally, the tool generates simulation code, in a master-slave fashion, using MPI.
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