| 1. |
- Hansson, Hans
(författare)
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ARTES - A network for Real-Time research and graduate Education in Sweden 1997-2006
- 2006
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This book summarizes the results of the Swedish national real-time systems research initiative ARTES and provides a few representative examples of the science and scientific results that have emerged from ARTES. ARTES was supported by the Swedish Foundation for Strategic Research (SSF) with totally 95 million SEK from 1998 to 2006. ARTES has united and enforced the Swedish research community in real-time and embedded systems, and has been instrumental in advancing Sweden's international position in this area. ARTES has provided a catalytic effect and loose coordination of a total research effort many times larger than the funding provided by SSF. This has created important synergies between disciplines, enforced industrial relevance in the research, and provided important academic and industrial networking for approximately 100 senior researchers and some 200 post-graduate students.
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| 2. |
- Eden, Amnon H., et al.
(författare)
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Towards a Mathematical Foundation for Design Patterns
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We identify a compact and sufficient set of building blocks which constitute most design patterns of the GoF catalog: uniform sets of classes or functions, function clans, class hierarchies, and regularities (morphisms) thereof. The abstractions observed are manifested within a model in symbolic logic and defined in LePUS, a declarative, higher order language. LePUS formulae concisely prescribe design patterns in a general, complete, and accurate manner. We provide a natural, condensed graphic notation for every LePUS formula and demonstrate how design patterns are faithfully portrayed by diagrams in this notation. We conclude by defining refinement (specialization) between patterns by means of predicate calculus and illustrate how the logical formalism of LePUS facilitates tool support for the recognition and implementation of design patterns.
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| 3. |
- Gustavsson, Andreas, et al.
(författare)
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Formalizing the Intent of Design Patterns. An Approach Towards a Solution to the Indexing Problem
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The intent section of a pattern description is written in easily understood, natural language, which unfortunately has the drawback of being too imprecise and unstructured for certain applications of the intent section.We will in this essay try to formalize the intent section of a pattern description. Our aim will be to find a structure within the intent description that will reduce ambiguities and at the same time make the classification of patterns easier. The classifications of patterns addresses the problem of "labeling" patterns into one of the following categories: Creational, Structural or Behavioural. Succeeding in classifying patterns by the intent does require that enough information for doing so is contained in the one to two sentences that make up the intent. Whether this is the case or not will be discussed in the essay.A formalized intent section of a pattern description can not replace the understandability of the natural language description but can be thought of as a complement to the standard structure to patterns today.
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| 4. |
- Jakobsson, Andreas, et al.
(författare)
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Two-Dimensional Capon Spectrum Analysis
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We present a computationally efficient algorithm for computing the 2-D Capon spectral estimator. The implementation is based on the fact that the 2-D data covariance matrix will have a Toeplitz-Block-Toeplitz structure, with the result that the inverse covariance matrix can be expressed in closed form by using a special case of the Gohberg-Heinig formula that is a function of strictly the forward 2-D prediction matrix polynomials. Furthermore, we present a novel method, based on a 2-D lattice algorithm, to compute the needed forward prediction matrix polynomials and discuss the difference in the so-obtained 2-D spectral estimate as compared to the one obtained by using the prediction matrix polynomials given by the Whittle-Wiggins-Robinson algorithm. Numerical simulations illustrate the clear computational gain in comparison to both the well-known classical implementation and the method recently published by Liu et al.
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| 5. |
- Jansson, Anders, et al.
(författare)
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Trafiksäkerhet och informationsmiljö i tågförarsystemet. Litteraturöversikt och olycksfallsanalyser
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This literature survey focuses on studies of the train driver system and its connections to other parts of the larger train traffic system. The main part of the studies concern Swedish conditions, but other references are included as well.In the first part, different ways of analysing accidents are discussed, including organisational aspects. In the second part, research results from different areas, all assumed to be relevant to the train driver task, are aggregated into a body of knowledge about the train driver system. Comparisons are made between the train driver task and other operator tasks. Further, the effects of a higher degree of automation are discussed.The task of driving a train is modelled as a dynamic decision task, where the driver's mental representation of the technical system and the optic flow of information are assumed to be important parts of the train driver task.In the last part of the literature survey, the content of 40 accident reports is discussed. Further, an analysis and a classification of Swedish train accidents are made by using CREAM (Hollnagel, 1998). The content of the reports, as well as the CREAM-method are evaluated, and different classification criteria are discussed.
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| 6. |
- Lin, Huimin, et al.
(författare)
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A Proof System for Timed Automata
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A proof system for timed automata is presented, based on a CCS-style language for describing timed automata. It consists of the standard monoid laws for bisimulation and a set of inference rules. The judgements of the proof system are \emphconditional equations of the form \phi\rhd t=u where ϕ is a clock constraint and t, u are terms denoting timed automata. It is proved that the proof system is complete over the recursion-free subset of the language. The completeness proof relies on the notion of \emphsymbolic timed bisimulation. Two variations of the axiomatisation are also discussed, one on timed automata by associating an invariant constraint to each node and the other on bisimulation by abstracting away delay transitions.
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| 7. |
- Lundqvist, Kristina, et al.
(författare)
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A Formal Model of a Ravenscar-Compliant Run-Time Kernel and Application Code
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Ravenscar tasking profile for Ada95 has been designed to allow implementation of safety critical systems in Ada. Ravenscar defines a tasking run-time system with deterministic behaviour and low complexity. We provide a formal model of the primitives provided by Ravenscar. This formal model can be used to verify safety properties of applications targeting a Ravenscar-compliant run-time system. As an illustration of this, we model a sample application and formally verify its correctness using the real-time model checker UPPAAL.
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| 8. |
- Söderström, Torsten, et al.
(författare)
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Parameter Estimation for Diffusion Models
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In many applications, for example in heat diffusion and in flow problems, it is important to describe the process behavior inside the particular medium. An example can be the strive for estimating certain parameters related to the material. This paper describes how the diffusion, modeled by a partial differential equation, can be solved using numerical methods and how results from the field of system identification can be utilized in order to estimate the parameters of interest.
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| 9. |
- Brus, Linda
(författare)
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Nonlinear identification of a solar heating system
- 2005
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Ingår i: Proceedings of the 2005 IEEE International Conference on Control Application. - : Dept. of Information Technology. - 0780393546 ; , s. 1491-1497
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Konferensbidrag (refereegranskat)abstract
- The use of solar heating systems is a way of exploiting the clean and free energy from the sun. To optimize the energy gain from such a system, where the main input, the solar insolation, is an uncontrollable variable, good models of the system dynamics are required. Identification methods are often either highly specialized for the application or require an extensive amount of data, especially when the dynamics studied are nonlinear. This paper shows that by application of a new recursive system identification technique, a small scale solar heating system can be modeled with very little data, without having to tailor the model structure to the application.
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| 10. |
- Brus, Linda
(författare)
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Nonlinear identification of an anaerobic digestion process
- 2005
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Ingår i: Proceedings of the 2005 IEEE International Conference on Control Applications. - : Dept. of Information Technology. - 0780393546 ; , s. 137-142
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Konferensbidrag (refereegranskat)abstract
- Anaerobic digestion in bioreactors is an important technology for environmental friendly treatment of organic waste. To optimize and control such processes accurate dynamic models of the process are needed. Unfortunately, modeling of anaerobic digestion often results in high order nonlinear models with many unknown parameters, a fact that complicates controller design. This paper attempts to circumvent this problem, by application of new recursive system identification techniques, thereby radically reducing the degree of the models and the number of parameters. Experiments show that a second order nonlinear model is sufficient for accurate modeling of the system.
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