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  • 1.
    Andersson, Anders
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering. Swedish National Road and Transportation Research Institute.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Models for Distributed Real-Time Simulation in a Vehicle Co-Simulator Setup2013In: Proceedings of the 5th International Workshop on Equation-Based Object-Oriented Modeling Languages and Tools; April 19, University of Nottingham, Nottingham, UK / [ed] Henrik Nilsson, Linköping: Linköping University Electronic Press, 2013, Vol. 84, p. 131-139Conference paper (Refereed)
    Abstract [en]

    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.

    Download full text (pdf)
    Models for Distributed Real-Time Simulation in a Vehicle Co-Simulator Setup
  • 2.
    Andersson, Niclas
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    Comparative Evaluation and Industrial Application of Code Generator Generators1992Conference paper (Other academic)
    Abstract [en]

    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.

  • 3.
    Andersson, Niclas
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    Generating Parallel Code from Object Oriented Mathematical Models1995In: PPOPP 1995, 1995, p. 48-57Conference paper (Refereed)
    Abstract [en]

    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.

  • 4.
    Andersson, Niclas
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    Object Oriented Mathematical Modelling and Compilation to Parallel Code1997In: Parallel Computing in Optimization / [ed] Athanasios Migdalas, Panos M. Pardalos and Sverre Storøy, Kluwer Academic Publishers, 1997Chapter in book (Other academic)
    Abstract [en]

    The current state of the art in programming for scientific computing is still rather low-level. The mathematical model behind a computing application usually is written using pen and paper, whereas the corresponding numerical software often is developed manually in Fortran or C. This is especially true in application areas such as mechanical analysis, where complex non-linear problems are the norm, and high performance is required. Ideally, a high-level programming environment would provide computer support for these development steps. This motivated the development of the ObjectMath system. Using ObjectMath, complex mathematical models may be structured in an object oriented way, symbolically simplified, and transformed to efficient numerical code in C++ or Fortran.

    However, many scientific computing problems are quite computationally demanding, which makes it desirable to use parallel computers. Unfortunately, generating parallel code from arbitrary mathematical models is an intractable problem. Therefore, we have focused most of our efforts on a specific problem domain where the main computation is to solve ordinary differential equation systems where most of the computing time is spent in application specific code, rather than in the serial solver kernel. We have investigated automatic parallelisation of the computation of ordinary differential equation systems at three different levels of granularity: the equation system level, the equation level, and the clustered task level. At the clustered task level we employ domain specific knowledge and existing scheduling and clustering algorithms to partition and distribute the computation.

  • 5.
    Andersson, Niclas
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Overview and industrial application of code generator generators1996In: Journal of Systems and Software, ISSN 0164-1212, E-ISSN 1873-1228, Vol. 32, no 3, p. 185-214Article in journal (Refereed)
    Abstract [en]

    During the past 10 to 15 years, there has been active research in the area of automatically generating the code generator part of compilers from formal specifications. However, little has been reported on the application of these systems in an industrial setting. This paper attempts to fill this gap, in addition to providing a tutorial overview of the most well-known methods. Four systems for automatic generation of code generators are described in this paper. CGSS, BEG, TWIG and BURG. CGSS is an older Graham-Glanville style system based on pattern matching through parsing, whereas BEG, TWIG, and BURG 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 allocations within automatically generated code generators are described, and some solutions are proposed. In addition, the specification of a full code generator for SUN SPARC with register windows using the BEG system is described. 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 and instruction scheduling with instruction selection, when both are generated from declarative specifications.

  • 6.
    Aronsson, Peter
    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.
    A Task Merging Technique for Parallelization of Modelica Models2005In: 4th International Modelica Conference, 2005, p. -128Conference paper (Refereed)
    Abstract [en]

    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.

    Download full text (pdf)
    fulltext
  • 7.
    Aronsson, Peter
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    Automatic Parallelization in OpenModelica2004Conference paper (Refereed)
  • 8.
    Aronsson, Peter
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Multiprocessor Scheduling of Simulation Code from Modelica Models2002Conference paper (Refereed)
  • 9.
    Aronsson, Peter
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    Parallel Code Generation in MathModelica / An Object Oriented Component Based Simulation Environment2001In: Proceedings of Workshop on Parallel/High Performance Object-Oriented Scientific Computing (POOSC’01), 2001Conference paper (Refereed)
    Abstract [en]

    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.

    Download full text (pdf)
    fulltext
  • 10.
    Aronsson, Peter
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Task Merging and Replication using Graph Rewriting2003Conference paper (Refereed)
  • 11.
    Aronsson, Peter
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Saldamli, Levon
    Linköping University, Department of Computer and Information Science.
    Bunus, Peter
    Linköping University, Department of Computer and Information Science.
    Incremental declaration handling in Open Source Modelica2002Conference paper (Refereed)
  • 12.
    Aronsson, Peter
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Saldamli, Levon
    Linköping University, Department of Computer and Information Science.
    Bunus, Peter
    Linköping University, Department of Computer and Information Science.
    Nyström, Kaj
    Linköping University, Department of Computer and Information Science.
    Meta Programming and Function Overloading in OpenModelica2003Conference paper (Refereed)
  • 13.
    Asghar, Adeel
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pfeiffer, Andreas
    DLR Institute of System Dynamic and Control, Wessling, Tyskland.
    Palanisamy, Arunkumar
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Mengist, Alachew
    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, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Automatic Regression Testing of Simulation Models and Concept for Simulation of Connected FMUs in PySimulator2015In: Proceedings of the 11th International Modelica Conference: Versailles, France, September 21-23, 2015 / [ed] Peter Fritzson, Hilding Elmqvist, Linköping, 2015, p. 671-679Conference paper (Refereed)
    Abstract [en]

    The Modelica and FMI tool ecosystem is growing each year with new tools and methods becoming available. The open Modelica standard promises portability but it is important to ensure that a certain model behaves the same in different Modelica tools or in a different version of the same tool. It is also very important (for model evolution) to check that a new version of the same model produces comparable results. Finally, it is desirable to verify that a model exported in FMU form from a Modelica tool gives exactly the same results as the original model. This paper presents a framework for automatic regression testing as part of PySimulator which provides an efficient and concise way of testing if a model or a range of models behaves in the same way in several tools or versions of a tool by checking that the results produced are essentially identical. The FMI standard has been adopted by many tool vendors and is growing in popularity each year. This paper proposes a concept for building and simulating a system made from connected FMUs generated by different tools. The FMUs for Co-Simulation can be connected together using a GUI. The system model built graphically in this way can be saved for later use or simulated directly inside PySimulator. Active development is going on to support simulation of connected FMUs for Model Exchange.

  • 14.
    Asghar, Adeel
    et al.
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Pop, Adrian
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Sjölund, Martin
    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.
    Efficient Debugging of Large Algorithmic Modelica Applications2012Conference paper (Refereed)
    Abstract [en]

    Modelica models often contain functions with algorithmic code. The fraction of algorithmiccode is increasing in Modelica models since Modelica, in addition to equation-based modeling, is also used for embedded system control code and symbolic model transformations in compilers using the MetaModelica language extension. For these reasons, debugging of algorithmic Modelica code is becoming increasingly relevant.

    Our earlier work in debuggers for the algorithmic subset of Modelica used trace-based techniques. These have the advantages of being very portable, but turned out to have too much overhead for very large applications.

    The new debugger is the first Modelica debugger that can operate without trace information. Instead it communicates with a low-level C-language symbolic debugger, the Gnu debugger GDB, to directly extract information from a running executable, set and remove breakpoints, etc. This is made possible by the new bootstrapped OpenModelica compiler which keeps track of a detailed mapping from the high level Modelica code down to the generated C code compiled to machine code.

    The debugger is operational, supports browsing of both standard Modelica data structures and tree/list data structures, and operates efficiently on large applications such as the OpenModelica compiler with more than 100 000 lines of code.

    Download full text (pdf)
    fulltext
  • 15.
    Asghar, Syed Adeel
    et al.
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Tariq, Sonia
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Torabzadeh-Tari, Mohsen
    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.
    Pop, Adrian
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Sjölund, Martin
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Vasaiely, Parham
    EADS Innovation Works, Engineering & Architecture, Hamburg, Germany.
    Schamai, Wladimir
    EADS Innovation Works, Engineering & Architecture, Hamburg, Germany.
    An Open Source Modelica Graphic Editor Integrated with Electronic Notebooks and Interactive Simulation2011In: Proceedings of the 8th International Modelica Conference, March 20th-22nd, Technical Univeristy, Dresden, Germany / [ed] Christoph Clauß, Linköping: Linköping University Electronic Press, 2011, Vol. 63, p. 739-747Conference paper (Refereed)
    Abstract [en]

    This paper describes the first open source Modelica graphic editor which is integrated with interactive electronic notebooks and online interactive simulation. The work is motivated by the need for easy-to-use graphic editing of Modelica models using OpenModelica, as well as needs in teaching where the student should be able to interactively modify and simulate models in an electronic book. Models can be both textual and graphical. The interactive online simulation makes the simulation respond in real-time to model changes, which is useful in a number of contexts including immediate feedback to students.

    Download full text (pdf)
    fulltext
  • 16.
    Auguston, Mikhail
    et al.
    New Mexico State University Las Cruces, USA.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    PARFORMAN - an Assertion Language for Specifying Behavior when Debugging Parallel Applications1996In: International journal of software engineering and knowledge engineering, ISSN 0218-1940, Vol. 6, no 4, p. 609-640Article in journal (Refereed)
    Abstract [en]

    PARFORMAN (PARallel FORMal ANnotation language) is a high-level specification language for expressing intended behavior or known types of error conditions when debugging or testing parallel programs. Models of intended or faulty target program behavior can be succinctly specified in PARFORMAN. These models are then compared with the actual behavior in terms of execution traces of events, in order to localize possible bugs. PARFORMAN can also be used as a general language for expressing computations over target program execution histories. PARFORMAN is based on a precise axiomatic model of target program behavior. This model, called H-space (History-space), is formally defined through a set of general axioms about three basic relations, which may or may not hold between two arbitrary events: they may be sequentially ordered (SEQ), they may be parallel (PAR), or one of them might be included in another composite event (IN). The general notion of composite event is exploited systematic.

  • 17.
    Auguston, Mikhail
    et al.
    University of Latvia, Riga.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    PARFORMAN - an Assertion Language for Specifying Behaviour when Debugging Parallel Applications1993In: Parallel and Distributed Processing, 1993, IEEE , 1993, p. 150-157Conference paper (Refereed)
    Abstract [en]

    PARFORMAN (PARallel FORMal ANnotation language) is a specification language for expressing the intended behaviour or known types of error conditions when debugging or testing parallel programs. The high-level debugging approach which is supported by PARFORMAN is model-based. Models of intended or faulty behaviour can be succinctly specified in PARFORMAN. These models are then compared with the actual behaviour in terms of execution traces of events, in order to localize possible bugs. PARFORMAN is based on an axiomatic model of target program behaviour. This model, called H-space (history-space), is formally defined through a set of general axioms about three basic relations between events. Events may be sequentially ordered, they may be parallel, or one of them might be included in another composite event. The notion of an event grammar is introduced to describe allowed event patterns over a certain application domain or language. Auxiliary composite events such as snapshots are introduced to be able to define the notion “occurred at the same time” at suitable levels of abstraction. In addition to debugging and testing, PARFORMAN can also be used to specify profiles and performance measurements

  • 18. Bachmann, Bernhard
    et al.
    Aronsson, Peter
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Robust Initialization of Differential Algebraic Equations2006Conference paper (Refereed)
  • 19.
    Bachmann, Bernhard
    et al.
    Dept. Mathematics and Engineering, University of Applied Sciences, Bielefeld, Germany.
    Ochel, Lennart
    Dept. Mathematics and Engineering, University of Applied Sciences, Bielefeld, Germany.
    Ruge, Vitalij
    Dept. Mathematics and Engineering, University of Applied Sciences, Bielefeld, Germany.
    Gebremedhin, Mahder
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Fritzson, Peter
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Nezhadali, Vaheed
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Sivertsson, Martin
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Parallel Multiple-Shooting and Collocation Optimization with OpenModelica2012In: Proceedings of the 9th International MODELICA Conference; September 3-5; 2012; Munich; Germany, Linköping University Electronic Press, 2012, p. 659-668, article id 067Conference paper (Refereed)
    Abstract [en]

    Nonlinear model predictive control (NMPC) has become increasingly important for today’s control engineers during the last decade. In order to apply NMPC a nonlinear optimal control problem (NOCP) must be solved which needs a high computational effort.

    State-of-the-art solution algorithms are based on multiple shooting or collocation algorithms; which are required to solve the underlying dynamic model formulation. This paper describes a general discretization scheme applied to the dynamic model description which can be further concretized to reproduce the mul-tiple shooting or collocation approach. Furthermore; this approach can be refined to represent a total collocation method in order to solve the underlying NOCP much more efficiently. Further speedup of optimization has been achieved by parallelizing the calculation of model specific parts (e.g. constraints; Jacobians; etc.) and is presented in the coming sections.

    The corresponding discretized optimization problem has been solved by the interior optimizer Ipopt. The proposed parallelized algorithms have been tested on different applications. As industrial relevant application an optimal control of a Diesel-Electric power train has been investigated. The modeling and problem description has been done in Optimica and Modelica. The simulation has been performed using OpenModelica. Speedup curves for parallel execution are presented.

  • 20.
    Bilos, Rober
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    Experience from a Token Sequence Representation of Programs, Documents, and their Deltas1988Conference paper (Refereed)
    Abstract [en]

    A primary goal with this work has been to investigate the consequences of a token-based program and document representation. This representation lies between plain text and trees in complexity.We have found that a program or a document represented as a token sequence saves on the average 50 representation. Another advantage is that deltas between program versions stored in source code control systems become insensitive to changes in whitespace or formatting style. Statistics from version-handling, computation of deltas, and storage is presented in the paper.

  • 21.
    Broman, David
    et al.
    Linköping University, Department of Computer and Information Science.
    Aronsson, Peter
    MathCore Engineering.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Design Considerations for Dimensional Inference and Unit Consistency Checking in Modelica2008Conference paper (Refereed)
    Abstract [en]

    The Modelica language supports syntax for declaring physical units of variables, but it does not yet exist any defined semantics for how dimensional and unit consistency checking should be carried out. In this paper we explore different approaches and new constructs for improved dimensional inference and unit consistency checking in Modelica; both from an end-user, library, and tool perspective. A proposal for how dimensional inference and unit checking can be carried out is outlined and a prototype implementation is developed and verified using several examples from the Modelica standard library.

  • 22.
    Broman, David
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Aronsson, Peter
    MathCore Engineering.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap.
    Design Considerations for Dimensional Inference and Unit Consistency Checking in Modelica2008In: Proceedings of the 6th International Modelica Conference, Bielefeld, Germany: Modelica Association , 2008, p. 3-12Conference paper (Refereed)
    Abstract [en]

    The Modelica language supports syntax for declaring physical units of variables, but it does not yet exist any defined semantics for how dimensional and unit consistency checking should be carried out. In this paper we explore different approaches and new constructs for improved dimensional inference and unit consistency checking in Modelica; both from an end-user, library, and tool perspective. A proposal for how dimensional inference and unit checking can be carried out is outlined and a prototype implementation is developed and verified using several examples from the Modelica standard library.

  • 23.
    Broman, David
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Abstract Syntax Can Make the Definition of Modelica Less Abstract2007In: Proceedings of the 1st International Workshop on Equation-Based Object-Oriented Languages and Tools, Berlin, Germany, 2007, p. 111-126Conference paper (Refereed)
    Abstract [en]

    Modelica is an open standardized language used for modeling and simulation of complex physical systems. The language specification defines a formal concrete syntax, but the semantics is informally described using natural language. The latter makes the language hard to interpret, maintain and reason about, which affect both tool development and language evolution. Even if a completely formal semantics of the Modelica language can be seen as a natural goal, it is a well-known fact that defining understandable and concise formal semantics specifications for large and complex languages is a very hard problem. In this paper, we will discuss different aspects of formulating a Modelica specification; both in terms of what should be specified and how it can be done. Moreover, we will further argue that a “middle-way” strategy can make the specification both clearer and easier to reason about. A proposal is outlined, where the current informally specified semantics is complemented with several grammars, specifying intermediate representations of abstract syntax. We believe that this kind of evolutionary strategy is easier to gain acceptance for, and is more realistic in the short-term, than a revolutionary approach of using a fully formal semantics definition of the language.

  • 24.
    Broman, David
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap.
    Abstract Syntax Can Make the Definition of Modelica Less Abstract2007In: Proceedings of the 1st International Workshop on Equation-Based Object-Oriented Languages and Tools, Berlin, Germany, 2007, p. 111-126Conference paper (Refereed)
    Abstract [en]

    Modelica is an open standardized language used for modeling and simulation of complex physical systems. The language specification defines a formal concrete syntax, but the semantics is informally described using natural language. The latter makes the language hard to interpret, maintain and reason about, which affect both tool development and language evolution. Even if a completely formal semantics of the Modelica language can be seen as a natural goal, it is a well-known fact that defining understandable and concise formal semantics specifications for large and complex languages is a very hard problem. In this paper, we will discuss different aspects of formulating a Modelica specification; both in terms of what should be specified and how it can be done. Moreover, we will further argue that a “middle-way” strategy can make the specification both clearer and easier to reason about. A proposal is outlined, where the current informally specified semantics is complemented with several grammars, specifying intermediate representations of abstract syntax. We believe that this kind of evolutionary strategy is easier to gain acceptance for, and is more realistic in the short-term, than a revolutionary approach of using a fully formal semantics definition of the language.

  • 25.
    Broman, David
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Higher-Order Acausal Models2008In: EOOLT 2008 / [ed] Peter Fritzson, François Cellier, David Broman, Linköping University Electronic Press , 2008, p. 59-69Conference paper (Other academic)
    Abstract [en]

    Current equation-based object-oriented (EOO) languages typically contain a number of fairly complex language constructs for enabling reuse of models. However, support for model transformation is still often limited to scripting solutions provided by tool implementations. In this paper we investigate the possibility of combining the well known concept of higher-order functions, used in standard functional programming languages, with acausal models. This concept, called Higher-Order Acausal Models (HOAMs), simplifies the creation of reusable model libraries and model transformations within the modeling language itself. These transformations include general model composition and recursion operations and do not require data representation/reification of models as in metaprogramming/metamodeling. Examples within the electrical and mechanical domain are given using a small research language. However, the language concept is not limited to a particular language, and could in the future be incorporated into existing commercially available EOO-languages.

  • 26.
    Broman, David
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    High-Order Acausal Models2009In: Simulation news europe, ISSN 0929-2268, Vol. 19, no 1Article in journal (Refereed)
  • 27.
    Broman, David
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap.
    High-Order Acausal Models2009In: Simulation News Europe, ISSN 0929-2268, Vol. 19, no 1Article in journal (Refereed)
    Abstract [en]

    Current equation-based object-oriented (EOO) languages typically contain a number of fairly complex language constructs for enabling reuse of models. However, support for model transformation is still often limited to scripting solutions provided by tool implementations. In this paper we investigate the possibility of combining the well known concept of higher-order functions, used in standard functional programming languages, with acausal models. This concept, called Higher-Order Acausal Models (HOAMs), simplifies the creation of reusable model libraries and model transformations within the modeling language itself. These transformations include general model composition and recursion operations and do not require data representation/ reification of models as in metaprogramming/metamodeling. Examples within the electrical and mechanical domain are given using a small research language. However, the language concept is not limited to a particular language, and could in the future be incorporated into existing commercially available EOO-languages.

  • 28.
    Broman, David
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Ideas for Security Assurance in Security Critical Software using Modelica2005Conference paper (Refereed)
    Abstract [en]

    Due to the increasing number of vulnerabilities in software systems and customers- need to trust the producers- development process, third party security evaluations, such as Common Criteria (CC), are today commonly used to provide assurance of security critical software. Modelica is a modern, strongly typed, declarative, and object-oriented language for modeling and simulation of complex systems. In this paper we sketch two ideas for improving security assurance, by expanding the scope of Modelica into also becoming a declarative modeling language for other application areas than simulation.

  • 29.
    Broman, David
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap.
    Ideas for Security Assurance in Security Critical Software using Modelica2005Conference paper (Refereed)
    Abstract [en]

    Due to the increasing number of vulnerabilities in software systems and customers- need to trust the producers- development process, third party security evaluations, such as Common Criteria (CC), are today commonly used to provide assurance of security critical software. Modelica is a modern, strongly typed, declarative, and object-oriented language for modeling and simulation of complex systems. In this paper we sketch two ideas for improving security assurance, by expanding the scope of Modelica into also becoming a declarative modeling language for other application areas than simulation.

  • 30.
    Broman, David
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    Type Safety of Equation-Based Object-Oriented Modeling Languages2006Conference paper (Refereed)
  • 31.
    Broman, David
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Type Safety of Equation-Based Object-Oriented Modeling Languages2006Other (Other (popular science, discussion, etc.))
  • 32.
    Broman, David
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Furic, Sébastien
    Imagine, France.
    Types in the Modelica Language2006Conference paper (Other academic)
    Abstract [en]

     

    Modelica is an object-oriented language designed

    for modeling and simulation of complex physical

    systems. To enable the possibility for an engineer

    to discover errors in a model, languages and com-

    pilers are making use of the concept of types and

    type checking. This paper gives an overview of

    the concept of types in the context of the Model-

    ica language. Furthermore, a new concrete syntax

    for describing Modelica types is given as a starting

    point to formalize types in Modelica. Finally, it is

    concluded that the current state of the Modelica

    language specification is too informal and should

    in the long term be augmented by a formal defin-

    ition.

     

  • 33.
    Broman, David
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap.
    Furic, Sébastien
    Imagine, France.
    Types in the Modelica Language2006In: Proceedings of the Fifth International Modelica Conference, 2006, p. 303-315Conference paper (Refereed)
    Abstract [en]

    Modelica is an object-oriented language designed for modeling and simulation of complex physical systems. To enable the possibility for an engineer to discover errors in a model, languages and compilers are making use of the concept of types and type checking. This paper gives an overview of the concept of types in the context of the Modelica language. Furthermore, a new concrete syntax for describing Modelica types is given as a starting point to formalize types in Modelica. Finally, it is concluded that the current state of the Modelica language specification is too informal and should in the long term be augmented by a formal definition.

     

  • 34.
    Broman, David
    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, Software and Systems. Linköping University, The Institute of Technology.
    Hedin, Görel
    Lund University, Sweden.
    Åkesson, Johan
    Lund University, Sweden.
    A comparison of two metacompilation approaches to implementing a complex domain-specific language2012In: Proceedings of the 27th Annual ACM Symposium on Applied Computing, Association for Computing Machinery (ACM), 2012, p. 1919-1921Conference paper (Refereed)
    Abstract [en]

    Operational semantics and attribute grammars are examples of formalisms that can be used for generating compilers. We are interested in finding similarities and differences in how these approaches are applied to complex languages, and for generating compilers of such maturity that they have users in industry.

    As a specific case, we present a comparative analysis of two compilers for Modelica, a language for physical modeling, and which contains numerous compilation challenges. The two compilers are OpenModelica, which is based on big-step operational semantics, and JModelica.org, which is based on reference attribute grammars.

  • 35.
    Broman, David
    et al.
    Linköpings universitet, PELAB - Laboratoriet för programmeringsomgivningar.
    Fritzson, Peter
    Linköpings universitet, Programvara och system.
    Hedin, Görel
    Lund University, Sweden.
    Åkesson, Johan
    Lund University, Sweden.
    A comparison of two metacompilation approaches to implementing a complex domaispecific language2012In: Proceedings of the 27th Annual ACM Symposium on Applied Computing (SAC), 2012, p. 1919-1921Conference paper (Refereed)
    Abstract [en]

    Operational semantics and attribute grammars are examples of formalisms that can be used for generating compilers. We are interested in finding similarities and differences in how these approaches are applied to complex languages, and for generating compilers of such maturity that they have users in industry.

    As a specific case, we present a comparative analysis of two compilers for Modelica, a language for physical modeling, and which contains numerous compilation challenges. The two compilers are OpenModelica, which is based on big-step operational semantics, and JModelica.org, which is based on reference attribute grammars.

  • 36.
    Broman, David
    et al.
    Linköping University, Department of Computer and Information Science.
    Nyström, Kaj
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Determining Over- and Under-Constrained Systems of Equations using Structural Constraint Delta2006Conference paper (Other academic)
    Abstract [en]

    Computer aided modeling and simulation of complex physical systems, using components from multiple application domains, such as electrical, mechanical, and hydraulic, have in recent years witnessed a significant growth of interest. In the last decade, equation-based object-oriented (EOO) modeling languages, (e.g. Modelica, gPROMS, and VHDL-AMS) based on acausal modeling using Differential Algebraic Equations (DAEs), have appeared. With such languages, it is possible to model physical systems at a high level of abstraction by using reusable components.A model in an EOO language needs to have the same number of equations as unknowns. A previously unsolved problem concerning this property is the efficient detection of over- or under-constrained models in the case of separately compiled models.This paper describes a novel technique to determine over- and under-constrained systems of equations in models, based on a concept called structural constraint delta. In many cases it is also possible to locate the source of the constraint-problem. Our approach makes use of static type checking and consists of a type inference algorithm. We have implemented it for a subset of the Modelica language, and successfully validated it on several examples.

  • 37.
    Broman, David
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Sweden.
    Nyström, Kaj
    Linköpings universitet, Institutionen för datavetenskap, Sweden.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Sweden.
    Determining Over- and Under-Constrained Systems of Equations using Structural Constraint Delta2006In: Proceedings of the 5th International Conference on Generative Programming and Component Engineering, 2006, p. 151-160Conference paper (Refereed)
    Abstract [en]

    Computer aided modeling and simulation of complex physical systems, using components from multiple application domains, such as electrical, mechanical, and hydraulic, have in recent years witnessed a significant growth of interest. In the last decade, equation-based object-oriented (EOO) modeling languages, (e.g. Modelica, gPROMS, and VHDL-AMS) based on acausal modeling using Differential Algebraic Equations (DAEs), have appeared. With such languages, it is possible to model physical systems at a high level of abstraction by using reusable components.A model in an EOO language needs to have the same number of equations as unknowns. A previously unsolved problem concerning this property is the efficient detection of over- or under-constrained models in the case of separately compiled models.This paper describes a novel technique to determine over- and under-constrained systems of equations in models, based on a concept called structural constraint delta. In many cases it is also possible to locate the source of the constraint-problem. Our approach makes use of static type checking and consists of a type inference algorithm. We have implemented it for a subset of the Modelica language, and successfully validated it on several examples.

  • 38.
    Buffoni, Lena
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Ochel, Lennart
    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.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Fors, Niklas
    Lund Univ, Sweden.
    Hedin, Gorel
    Lund Univ, Sweden.
    Taha, Walid
    Halmstad Univ, Sweden.
    Sjölund, Martin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Open Source Languages and Methods for Cyber-Physical System Development: Overview and Case Studies2021In: Electronics, E-ISSN 2079-9292, Vol. 10, no 8, article id 902Article in journal (Refereed)
    Abstract [en]

    Industrial cyber-physical system products interleave hardware, software, and communication components. System complexity is increasing simultaneously with increased demands on quality and shortened time-to-market. To effectively support the development of such systems, we present languages and tools for comprehensive integrated model-based development that cover major phases such as requirement analysis, design, implementation, and maintenance. The model-based approach raises the level of abstraction and allows to perform virtual prototyping by simulating and optimizing system models before building physical products. Moreover, open standards and open source implementations enable model portability, tool reuse and a broader deployment. In this paper we present a general overview of the available solutions with focus on Modelica/OpenModelica, Bloqqi, and Acumen. The paper presents contributions to these languages and environments, including symbolic-numeric modeling, requirement verification, code generation, model debugging, design optimization, graphical modeling, and variant handling with traceability, as well a general discussion and conclusions.

    Download full text (pdf)
    fulltext
  • 39.
    Buffoni-Rogovchenko, Lena
    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.
    Nyberg, Mattias
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Garro, Alfredo
    University of Calabria, Italy.
    Tundis, Andrea
    University of Calabria, Italy.
    Requirement Verification and Dependency Tracing During Simulation in Modelica2013In: EUROSIM '13, IEEE Press, 2013, p. 561-566Conference paper (Refereed)
    Abstract [en]

    Requirement verification is an important part of the development process, and the increasing system complexity has exacerbated the need for integrating this step into a formalized model driven development process, providing a dedicated methodology as well as tool support. In this paper the authors propose an extension for Modelica, an equation-based language for system modeling, that will allow to represent system requirements in the same formalism as the design model, thus reducing the need for transformations between different specialized formalisms, lowering maintenance and modification costs, and benefitting from the expression and simulation capabilities, as well as extensive tool support of Modelica. The object-oriented nature of the approach provides the advantages of modular design and hierarchical structuring of the requirement model. This paper also illustrates, with the help of an example, how requirement verification can be used alongside the simulation process to trace the components responsible for requirement violations. To this end, we introduce a formalism for expressing relationships between components and requirements, as well as a tracing algorithm.

  • 40.
    Bunus, Peter
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Engelson, Vadim
    Linköping University, Department of Computer and Information Science. 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.
    Mechanical Models Translation and Simulation in Modelica2000Conference paper (Refereed)
  • 41.
    Bunus, Peter
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    A Debugging Scheme for Declarative Equation Based Modeling Languages2002In: Practical Aspects of Declarative Languages / [ed] Shriram Krishnamurthi (Editor),‎ C.R. Ramakrishnan (Editor) Be the first to review this item, Springer Berlin/Heidelberg, 2002Conference paper (Refereed)
    Abstract [en]

    This paper concerns the static analysis for debugging purposes of programs written in declarative equation based modeling languages. We first give an introduction to declarative equation based languages and the consequences equation based programming has for debugging. At the same time, we examine the particular debugging problems posed by Modelica, a declarative equation based modeling language. A brief overview of the Modelica language is also given. We also present our view of the issues and solutions based on a proposed framework for debugging declarative equation based languages. Program analysis solutions for program understanding and for static debugging of declarative equation based languages, based on bipartite graph decomposition, are presented in the paper. We also present an efficient way to annotate the underlying equations in order to help the implemented debugger to eliminate the heuristics involved in choosing the right error fixing solution. This also provides means to report the location of an error caught by the static analyzer or by the numeric solver, consistent with the user’s perception of the source code and simulation model.

    Download full text (pdf)
    fulltext
  • 42.
    Bunus, Peter
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    An Interactive Environment for Debugging Declarative Equation-based Languages2001Conference paper (Refereed)
    Abstract [en]

    In this paper we present a general framework for debugging declarative equation based languages. This paper uses certain existing bipartite graph based techniques to derive debugging algorithms for the structural diagnosis of simulation models specified in declarative equation based modeling languages. An efficient way of annotating the underlying equations of a simulation model in order to help the user to take error-fixing decisions is also presented. This also provides means to report the location of the error caught bythe extended static analyzer or by the numeric solver, consistent with the user’s perception of the source code and the simulation model. We also present a unified reasoning process in order to relax over-constrained systems and obtain a consistent simulation model that supports an enhanced user interaction. The interactive debugging environment provides to the user a greater confidence in the correctness of the simulation model and helps them to resolve conflicting situations when multiple elimination choices are possible. A prototype debugger is implemented.

    Download full text (pdf)
    fulltext
  • 43.
    Bunus, Peter
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    Application of Graph Decomposition Techniques to Debugging Declarative Equation Based Languages2001Conference paper (Refereed)
    Abstract [en]

    This paper concerns the static analysis for debugging purposes of programs written in declarative equation based modeling languages. We first give an introduction to declarative equation based languages and the consequences equation based programming has for debugging. At the same time, we examine the particular debugging problems posed by Modelica, a declarative equation based modeling language. A brief overview of the Modelica language is also given. We also present our view of the issues and solutions based on a proposed framework for debugging declarative equation based languages. Program analysis solutions for program understanding and for static debugging of declarative equation based languages, based on bipartite graph decomposition, are presented in the paper. We also present an efficient way to annotate the underlying equations in order to help the implemented debugger to eliminate the heuristics involved in choosing the right error fixing solution. This also provides means to report the location of an error caught by the static analyzer or by the numeric solver, consistent with the user’s perception of the source code and simulation model.

    Download full text (pdf)
    fulltext
  • 44.
    Bunus, Peter
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Automated static analysis of equation-based components2004In: Simulation (San Diego, Calif.), ISSN 0037-5497, E-ISSN 1741-3133, Vol. 80, no 7-8, p. 321-345Article in journal (Refereed)
    Abstract [en]

    Mathematical modeling and the simulation of complex physical systems are emerging as key technologies in engineering. The availability of static analyzers and automatic debuggers for detecting structural and numerical inconsistencies in the simulation models is crucial. To address this need, the authors propose a methodology for detecting and repairing overconstrained and underconstrained situations based on graph-theoretical approaches. Components and equations that cause the irregularities are automatically isolated, and meaningful error messages for the user are elaborated. The authors have implemented the AMOEBA (Automatic Modelica Equation-Based Analyzer) environment to support the development and specification of correct equation-based simulation models by applying graph-theoretical approaches and semiautomatic debugging techniques. The implementation architecture and preliminary experiments with a prototype debugger integrated in the symbolic and numeric engine, ModSimPack, of the Modelica language compiler are presented and discussed.

  • 45.
    Bunus, Peter
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    DEVS-Based Multi-Formalism Modeling and Simulation in Modelica2000Conference paper (Refereed)
  • 46.
    Bunus, Peter
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    Semantics guided filtering of combinatorial graph transformations in declarative equation-based languages2002In: Source Code Analysis and Manipulation, 2002, 2002, p. 163-172Conference paper (Refereed)
    Abstract [en]

    This paper concerns the use of static analysis for debugging purposes of declarative object-oriented equation-based modeling languages. We propose a framework where over- and under-constraining situations present in simulation models specified in such languages are detected by combinatorial graph transformations performed on the flattened intermediate code and filtered by the semantic transformation rules derived from the original language. This is powerful enough to statically detect a broad range of errors without having to execute the simulation model. Debuggers associated with simulation environments for such languages can provide efficient error-fixing strategies based on the graph-based representation of the intermediate code. The emphasis, in this paper, is on detecting and debugging over-constraining equations, which are present in some simulation model specifications. We discuss various ways in which we have extended our approach to allow static global analysis of the original modeling source code.

    Download full text (pdf)
    fulltext
  • 47.
    Bunus, Peter
    et al.
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Semi-automatic Fault Localization and Behaviour Verification for Physical System Simulation Models2003Conference paper (Refereed)
  • 48.
    Bunus, Peter
    et al.
    Linköping University, Department of Computer and Information Science. 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.
    The Need for Debugging Tools for Declarative Equation Based Simulation Languages2000Conference paper (Refereed)
  • 49. Bydler, Roger
    et al.
    Björkström, Anders
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Gullberg, Anders
    KTH; Stockholmsforskningen Stockholms stad.
    Schütt, Lars
    Sundblad, Yngve
    KTH.
    Omställning till ett hållbart transport- och mobilitetssystem med människan i centrum2022Report (Refereed)
    Abstract [en]

    The global warming is the greatest challenge of our time. The first report by the UN climate panel, IPCC, was published 1990. Thus, it is more than 30 years since the research community concluded that a rapid climate change is ongoing. Since then new research has shown that already at 1.5 degrees global warming there are definite risks for environments needed by both humans, animals, and nature. This motivated a large majority of the world’s countries to sign the Paris Agreement at the UN climate conference, COP 21, in 2015. The Paris Agreement states that the countries of the World shall take action to keep the global average temperature increase far below 2.0 degrees and preferably below 1.5 degrees. Despite the fact that it is scientifically shown and generally accepted that human caused emissions is the completely dominating cause of the global warming, the necessary actions to reduce emissions are still missing. The average global temperature increase is now 1.1 degrees Celsius compared to pre-industrial times.       With this as background, the Swedish Climate Parliament (an NGO, www.klimatriksdagen.se) develops a set of proposals for climate policy actions based on Sweden’s commitments according to the Paris Agreement. The CO2 emission budget for Sweden 2020 according to these assumptions show that the Swedish emission budget will be used up latest 2035.

    This report about mobility and transport is an independent report and at the same time input to the Climate Parliament’s comprehensive climate-based transition plan. Domestic transport causes about a third of Sweden’s territorial emission. If we also include emissions from fuels stored in Sweden, bunkered fuels for aircraft and ships, Sweden’s emissions related to transport amounts to about 40 percent. The transport sector is characterized by many interactions to other sectors and requires large investments. The transition to a climate neutral neutral transport section within slightly more than a decade therefore requires powerful and rapidly executed actions.      The goal of an emission free transport sector for Sweden 2035 has been guiding the analysis and choice of actions. By putting this in relation to the situation of today, a number of alternative scenarios with different sets of actions to reach this goal have been developed. This methodology is called back-casting. Emission trajectories for these scenarios illustrate how emission reductions can be distributed over time. Moreover, dynamic system modeling and simulation has also been employed regarding analysis of how and when different actions should be executed.

    In this report we claim that the view of transport and transport planning must be fundamentally changed. Human needs and conditions, high availability, and low resource usage should be long term goals and the transport planning should be included in the general societal planning. A climate friendly mobility pattern must be created. People’s acceptance and engagement will be absolutely crucial for the success of the sustainability transition.    The proposed actions should be viewed in view of the commitments that Sweden has done and the CO2 budget for Sweden that becomes the consequence. Certain proposals may appear to be less popular and therefore difficult to implement. Nonetheless, even these are not enough. This is true especially for air traffic but also for person transport on road and at sea. Over time the proposed actions need to be extended and applied more strictly in order for the CO2 budget of the transport sector to be accommodated within the applicable CO2 budget.

    The introductory part of the report first presents a summary of the conclusions and proposals of the report, followed by the goals that need to be reached at the target year 2035. What will happen and which actions have been realized until the year 2035? Usually visions of the future starts at the current situation today and projects current trends forward in time. This has the drawback that the current situation and trends may lock thinking and prevent necessary actions. However, the climate induced transition will need such large and comprehensive changes that parts of today’s thinking, methodology and tradition have to be abandoned and replaced by new methods and creative solutions. The parts of the report that describe proposed actions are written based on what is applicable today. They should be decided on and executed very soon in order that necessary changes should happen in time. During this process re-evaluation of policies and solutions will need to be done continuously. New conditions and new possibilities will appear. The many solutions and actions and the connections and inter-relations between those that must be fulfilled to get the desired results indicate the complexity of the climate sustainability transition.

    Considerations and conclusions summarized:

    The short time available – since the transition to a climate friendly mobility and transport system needs to take place during a little bit more than a decade – results in requirements on decisions and implementation of powerful and rapidly implemented measures.

    • A fundamentally new point of view, a system perspective, is applied to mobility, transport, and their roles in society. Availability and measures related to different modes of transportation will be coordinated and supported in relation to societal benefits such as availability, equity, reduced climate impact, health, local environment, and biodiversity. The climate related transformation of the transport sector will be seriously begun only if these goals are used as guidance, in relation to available carbon dioxide budgets, abandoning todays’ forecast driven and short term oriented infra structure planning.
    • A digital system for dynamic and differentiated prices on usage of road infra structure – dynamic and differentiated road fees – coordinated with supply and a comprehensive public transport ticket system will influence traffic volumes, choice of transport mode, and create long term financing of public transport. The public investments will be financed from a general governmental fund.
    • Measures for reduced road traffic volumes are combined with actions to stimulate increased mobility on foot, via bicycle, or public transport, and a rapid electrification of motor vehicles.
    • Large scale investments are done within the railway system, public transport, charge infrastructure and broadband. These should be implemented very rapidly to contribute to reduced climate emissions until 2035.
    • The total emissions from the transport sector, including both biogenic and fossil carbon dioxide, are at a such a large order of magnitude that they cannot be completely eliminated to net zero until 2035 using practically available measures.
    • The national carbon dioxide budget for mobility and transport is regionalized at a level where the climate transition can be effectively coordinated in collaboration with affected parties and with support from governmental investment funds.
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  • 50.
    Cellier, François
    et al.
    ETH Zürich.
    Broman, DavidLinköping University, Department of Computer and Information Science.Fritzson, PeterLinköping University, Department of Computer and Information Science.Lee, EdwardUniversity of California, Berkeley.
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