liu.seSearch for publications in DiVA
Change search
Refine search result
1 - 8 of 8
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Order onlineBuy this publication >>
    Tinnerholm, John
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    A Composable and Extensible Environment for Equation-based Modeling and Simulation of Variable Structured Systems in Modelica2022Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Modeling and Simulation are usually used to solve real-world problems safely and efficiently by constructing digital models of Cyber-Physical Systems. The models can be simulated and analyzed with respect to requirements, and decisions about their design can be based on this analysis. In the latest years, the field of Modeling and Simulation has grown massively and is tackling systems with increased complexity. Thus, the process of modeling and simulating Cyber-Physical systems is becoming more and more complex. This increase requires modeling languages that can express systems with increasing complexity.

    Modelica is an open-standard declarative equation-based object-oriented language used to model various systems expressed using equations. Modelica tools can read the models, process them, and simulate them. However, the Modelica language and tools cannot express some concepts such as structural changes to the components or behavior of Cyber-Physical Systems during Simulation.

    In this thesis, we propose extensions of the Modelica language to support modeling so-called variable structure systems, that is, systems where the structure of the system varies during Simulation. The full Modelica language and the new extensions are supported by a novel composable programming environment framework called OpenModelica.jl written in the Julia language. The proposed Modelica language extensions can handle explicit and implicit modeling of variable structure systems by introducing new operators and, consequently, new semantics to the Modelica language.

    The explicit modeling is based on extensions that switch at runtime between continuous modes of operations with operators similar to the ones used in the specification of Modelica state-machines. The implicit modeling supports reconfiguration during runtime via recompilation. A Just-in-time compiler was implemented to handle the new semantics using the symbolic-numeric programming language Julia.

    We investigate the performance of our new framework and compare it with existing state-of-the-art Modelica tools on models with thousands of equations and variables. The results show that our extensions and proposed runtime framework is viable for simulating both usual Modelica models and models with variable structure systems.

    The conclusion is that the Modelica language can be extended further to support systems with variable structures with the addition of a few operators and JIT enhanced runtime system support. Based on the result of this thesis, we propose several directions for future work.

    Download full text (pdf)
    fulltext
    Download (png)
    presentationsbild
  • 2.
    Tinnerholm, John
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pop, Adrian
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Sjölund, Martin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    A Modular, Extensible, and Modelica-Standard-Compliant OpenModelica Compiler Framework in Julia Supporting Structural Variability2022In: Electronics, E-ISSN 2079-9292, Vol. 11, no 11, article id 1772Article in journal (Refereed)
    Abstract [en]

    Nowadays, industrial products are getting increasingly complex, and time-to-market is significantly shorter. Modeling and simulation tools for cyber-physical systems need to keep up with the increased complexity. This paper presents OpenModelica.jl, a modular and extensible Modelica compiler framework in Julia targeting ModelingToolkit.jl and supporting Variable Structured Systems. We extended the Modelica language with three new operators to support continuous-time mode-switching and reconfiguration via recompilation at runtime. Therefore, our compiler supports the Modelica language and variable structure systems via the aforementioned extensions. To our knowledge, there are no other Modelica tools available that support both standard Modelica and variable structure systems. We evaluated our framework using a standardized benchmark suite, in terms of simulation, compilation and recompilation performance. The results concerning compilation and simulation time performance were compared with the results of running the existing OpenModelica compiler with the same set of models. A custom benchmark was devised to estimate the cost in terms of recompilation when simulating variable structure systems. The performance experiments showed that OpenModelica.jl is currently about four times slower in terms of compilation time when compiling a transmission line model with tens of thousands of equations and variables. The difference in simulation performance between the two compilers was negligable. Furthermore, the impact of recompilation during the simulation was usually small compared with the simulation time for long simulations. The results are promising for a prototype, and we outline approaches to further improve both compilation and simulation performance as future research. 

    Download full text (pdf)
    fulltext
  • 3.
    Tinnerholm, John
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Casella, Francesco
    Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Italy.
    Pop, Adrian
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Towards Modeling and Simulation of Dynamic Overconstrained Connectors in Modelica2022In: Proceedings of Asian Modelica Conference 2022, Tokyo, Japan, November 24-25, 2022 / [ed] Prof. Tielong Shen, Dr. Rui Gao and Dr. Yutaka Hirano, Linköping University Electronic Press, 2022, p. 35-44Conference paper (Refereed)
    Abstract [en]

    Cyber-Physical Systems are ever-increasing in complexity and new methods and tools for developing them are needed. To support these highly dynamic systems, increasing the flexibility of the modeling languages is desirable. This paper proposes and examines a Modelica language extension to support dynamic overconstrained graphs with reconfiguration at runtime. Two applications of this new feature are also discussed: synchronous AC power systems and incompressible fluid networks. Reported findings suggest that supporting dynamic overconstrained graphs might yield performance benefits and provide the possibility of simulating systems that can not currently be simulated in existing Modelica tools.

  • 4.
    Alegroth, Emil
    et al.
    Blekinge Inst Technol, Sweden.
    Borch Petersen, Eline
    Linköping University, Department of Clinical and Experimental Medicine, Division of Speech language pathology, Audiology and Otorhinolaryngology. Linköping University, Faculty of Medicine and Health Sciences.
    Tinnerholm, John
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    A Failed attempt at creating Guidelines for Visual GUI Testing: An industrial case study2021In: 2021 14TH IEEE CONFERENCE ON SOFTWARE TESTING, VERIFICATION AND VALIDATION (ICST 2021), IEEE COMPUTER SOC , 2021, p. 340-350Conference paper (Refereed)
    Abstract [en]

    Software development is governed by guidelines that aim to improve the codes qualities, such as maintainability. However, whilst coding guidelines are commonplace for software, guidelines for testware are much less common. In particular, for GUI-based tests driven with image recognition, also referred to as Visual GUI Testing (VGT), explicit coding guidelines are missing. In this industrial case study, performed at the Swedish defence contractor Saab AB, we propose a set of coding guidelines for VGT and evaluate their impact on test scripts for an industrial, safety-critical system. To study the guidelines effect on maintenance costs, five representative manual test cases are each translated with and without the proposed guidelines in the two VGT tools SikuliX and EyeAutomate. As such, 20 test scripts were developed, with a combined development cost of more than 100 man-hours. Three of the tests are then maintained by one researcher and two practitioners for another version of the system and costs measured to evaluate return on investment. This analysis is complemented with observations and interviews to elicit practitioners perceptions and experiences with VGT. Results show that scripts developed with the guidelines had higher maintenance costs than scripts developed without guide-lines. This is supported by qualitative results that many of the guidelines are considered inappropriate, superfluous or unnecessary due to the inherent properties of the scripts, e.g. their natural small size, linear flows, natural separation of concerns, and more. We conclude that there are differences between VGT scripts and software that prohibit direct translation of guidelines between the two. As such, we consider our study as a failure but argue that several lessons can be drawn from our results to guide future research into guidelines for VGT and GUI-based test automation.

  • 5.
    Tinnerholm, John
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pop, Adrian
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Andreas, Heuermann
    Faculty of Engineering and Mathematics, Bielefeld University of Applied Sciences, Germany,.
    Sjölund, Martin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    OpenModelica.jl: A modular and extensible Modelica compiler framework in Julia targeting ModelingToolkit.jl2021In: Proceedings of the 14th International Modelica Conference / [ed] Martin Sjölund, Lena Buffoni, Adrian Pop and Lennart Ochel, Linköping: Linköping University Electronic Press , 2021, p. 109-117Conference paper (Refereed)
  • 6.
    Fritzson, Peter
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pop, Adrian
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Abdelhak, Karim
    Department of Engineering and Mathematics, Fachhochschule Bielefeld, Bielefeld, Germany.
    Asghar, Adeel
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Bachmann, Bernhard
    Department of Engineering and Mathematics, Fachhochschule Bielefeld, Bielefeld, Germany.
    Braun, Willi
    Department of Engineering and Mathematics, Fachhochschule Bielefeld, Bielefeld, Germany.
    Bouskela, Daniel
    Electricit´e de France, (EDF Lab), Chatou, France.
    Braun, Robert
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Buffoni, Lena
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Casella, Francesco
    Dip. Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy.
    Castro, Rodrigo
    Dept. Computer Science, Universidad de Buenos Aires, Argentina.
    Franke, Rüdiger
    ABB AG, Mannheim, Germany.
    Fritzson, Dag
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Gebremedhin, Mahder
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Heuermann, Andreas
    Department of Engineering and Mathematics, Fachhochschule Bielefeld, Bielefeld, Germany.
    Lie, Bernt
    University of South-Eastern Norway, Porsgrunn, Norway.
    Mengist, Alachew
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Mikelsons, Lars
    Linköping University.
    Moudgalya, Kannan
    Dept. of Chemical Engineering, IIT Bombay, Mumbai, India.
    Ochel, Lennart
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Palanisamy, Arunkumar
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Ruge, Vitalij
    Department of Engineering and Mathematics, Fachhochschule Bielefeld, Bielefeld, Germany.
    Schamai, Wladimir
    Danfoss Power Solutions GmbH & Co. OHG, Offenbach, Germany.
    Sjölund, Martin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Thiele, Bernhard Amadeus
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Tinnerholm, John
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Östlund, Per
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    The OpenModelica Integrated Environment for Modeling, Simulation, and Model-Based Development2020In: Modeling, Identification and Control, ISSN 0332-7353, E-ISSN 1890-1328, Vol. 41, no 4, p. 241-295Article in journal (Refereed)
    Abstract [en]

    OpenModelica is a unique large-scale integrated open-source Modelica- and FMI-based modeling, simulation, optimization, model-based analysis and development environment. Moreover, the OpenModelica environment provides a number of facilities such as debugging; optimization; visualization and 3D animation; web-based model editing and simulation; scripting from Modelica, Python, Julia, and Matlab; efficient simulation and co-simulation of FMI-based models; compilation for embedded systems; Modelica-UML integration; requirement verification; and generation of parallel code for multi-core architectures. The environment is based on the equation-based object-oriented Modelica language and currently uses the MetaModelica extended version of Modelica for its model compiler implementation. This overview paper gives an up-to-date description of the capabilities of the system, short overviews of used open source symbolic and numeric algorithms with pointers to published literature, tool integration aspects, some lessons learned, and the main vision behind its development.

    Download full text (pdf)
    fulltext
  • 7.
    Tinnerholm, John
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pop, Adrian
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Sjölund, Martin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Heuermann, Andreas
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Abdelhak, Karim
    Faculty of Engineering and Mathematics, Bielefeld University of Applied Sciences, Bielefeld, Germany.
    Towards an Open-Source Modelica Compiler in Julia2020In: Proceedings of Asian Modelica Conference 2020, Tokyo, Japan, October 08-09, 2020 / [ed] Dr. Rui Gao and Dr. Yutaka Hirano, Linköping: Linköping University Electronic Press, 2020, p. 143-151Conference paper (Refereed)
    Abstract [en]

    Recently the Julia language has become an option for scientific computing. As of 2020, efforts exist to provide libraries that emulate the equation-based modeling features provided by Modelica or otherwise provide such functionality in Julia. The issue with these approaches is that investment in standardization and libraries would be lost unless standard-complacency is guaranteed. We believe that it is possible to combine features from both by implementing such a compiler in Julia. We argue that this approach would open additional opportunities. One such being the handling of variable structure systems (VSS) within the framework of a Modelica standard-compliant compiler. The other being a proposed compiler architecture reminiscent of LLVM for equation-based object-oriented languages. Using the OpenModelica Compiler as a baseline, we verified the fidelity of our implementation by simulating a selected set of models. While there are performance penalties, we argue that improvements to the frontend would mitigate these issues.

    Download full text (pdf)
    fulltext
  • 8.
    Tinnerholm, John
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Sjölund, Martin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pop, Adrian
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Computer and Information Science, Software and Systems.
    Towards introducing just-in-time compilation in a Modelica compiler2019In: EOOLT '19: Proceedings of the 9th International Workshop on Equation-based Object-oriented Modeling Languages and Tools / [ed] Association for Computing Machinery, New York, NY, United States: ACM Press, 2019, p. 11-19Conference paper (Refereed)
    Abstract [en]

    We are investigating ways of introducing just-in-time compilation in a standard-compliant Modelica compiler, the Open-Modelica compiler (OMC). The main motivations are enabling extensions to support dynamically varying model structure, faster compilation, and faster recompilation of models after changes. We are investigating two approaches.

    The first approach is to adapt the low-level OpenModelica intermediate representation (IR) before code generation to be compatible with LLVM. In that way we can avoid generating intermediate C-code and instead generate LLVM IR in memory for just-in-time compilation (JIT).

    The second approach is to translate OMC itself written in MetaModelica to Julia, and thereby gain access to the JIT capabilities of LLVM. Another benefit of the second approach is the access to the Julia ecosystem, including a rich set of libraries for numerical computing.

    We have done a preliminary investigation of both approaches, with measurements on a selected sample of algorithms, and discovered that compilation-time of generated Julia code is slower compared to generating LLVM IR directly. We conclude that providing a standard-compliant Modelica compiler which supports a dynamically varying model structure is feasible and possible, and we believe that such a compiler can be provided by using Julia or MetaModelica.

1 - 8 of 8
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf