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Tzamaras, S., Adam, S. & Taha, W. (2021). Intelligent Techniques and Hybrid Systems Experiments Using the Acumen Modeling and Simulation Environment. In: Maglogiannis I.; Macintyre J.; Iliadis L. (Ed.), IFIP Advances in Information and Communication Technology: . Paper presented at 17th IFIP WG 12.5 International Conference on Artificial Intelligence Applications and Innovations, AIAI 2021, Virtual, Online, 25-27/06, 2021 (pp. 531-542). Cham: Springer, 627
Open this publication in new window or tab >>Intelligent Techniques and Hybrid Systems Experiments Using the Acumen Modeling and Simulation Environment
2021 (English)In: IFIP Advances in Information and Communication Technology / [ed] Maglogiannis I.; Macintyre J.; Iliadis L., Cham: Springer, 2021, Vol. 627, p. 531-542Conference paper, Published paper (Refereed)
Abstract [en]

Hybrid systems are dynamical systems of both continuous and discrete nature and constitute an important field of control systems theory and engineering. On the other hand, intelligent data processing has become one of the most critical devices of modern computer based systems as these systems operate in environments featuring increasing uncertainty and unpredictability. While these two approaches set completely different objectives, modern cyber-physical systems, taken as variants of hybrid systems, seem to constitute a field of increasing interest for applying intelligent techniques. Moreover, the examples of, not so recent, intelligent control systems are suggestive for considering a study on getting intelligent techniques close to hybrid systems. In this paper we present the experimental investigation we undertook in this direction. More specifically, we present and discuss the experiments carried out using Acumen a hybrid systems modeling and simulation environment. Without urging towards setting and solving questions of conceptual order we tried to figure out whether it is possible to represent intelligent behavior using a tool for modeling dynamical systems focusing on the study of its ability to permit the representation of both continuous and discrete intelligent techniques, namely, Reinforcement Learning and Hopfield neural networks. The results obtained are indicative of the problems related to the specific computational context and are useful in deriving conclusions concerning the functionality that needs to be provided by such modeling and simulation environments, in order to allow for the coexistence of hybrid systems and intelligent techniques. © 2021, IFIP International Federation for Information Processing

Place, publisher, year, edition, pages
Cham: Springer, 2021
Series
IFIP Advances in Information and Communication Technology (IFIPAICT), ISSN 1868-4238, E-ISSN 1868-422X ; 627
National Category
Control Engineering
Identifiers
urn:nbn:se:hh:diva-46087 (URN)10.1007/978-3-030-79150-6_42 (DOI)2-s2.0-85111887917 (Scopus ID)978-3-030-79149-0 (ISBN)978-3-030-79150-6 (ISBN)
Conference
17th IFIP WG 12.5 International Conference on Artificial Intelligence Applications and Innovations, AIAI 2021, Virtual, Online, 25-27/06, 2021
Available from: 2021-12-10 Created: 2021-12-10 Last updated: 2021-12-10Bibliographically approved
Buffoni, L., Ochel, L., Pop, A., Sjölund, M., Fritzson, P., Fors, N., . . . Taha, W. (2021). Open source languages and methods for cyber-physical system development: Overview and case studies. Electronics, 10(8), Article ID 902.
Open this publication in new window or tab >>Open source languages and methods for cyber-physical system development: Overview and case studies
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2021 (English)In: Electronics, E-ISSN 2079-9292, Vol. 10, no 8, article id 902Article in journal (Refereed) Published
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. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Place, publisher, year, edition, pages
Basel: , 2021
Keywords
Cyber-physical systems, Equation-based, Modeling languages, Open source, Simulation
National Category
Computer Sciences
Identifiers
urn:nbn:se:hh:diva-45952 (URN)10.3390/electronics10080902 (DOI)000644022500001 ()2-s2.0-85103821011 (Scopus ID)
Funder
VinnovaSwedish Foundation for Strategic Research
Available from: 2021-11-29 Created: 2021-11-29 Last updated: 2021-11-29Bibliographically approved
Moggi, E., Taha, W. & Thunberg, J. (2020). Sound over-approximation of probabilities. Acta Cybernetica, 24(3), 269-285
Open this publication in new window or tab >>Sound over-approximation of probabilities
2020 (English)In: Acta Cybernetica, ISSN 0324-721X, Vol. 24, no 3, p. 269-285Article in journal (Refereed) Published
Abstract [en]

Safety analysis of high confidence systems requires guaranteed bounds on the probabilities of events of interest. Establishing the correctness of algorithms that aim to compute such bounds is challenging. We address this problem in three steps. First, we use monadic transition systems (MTS) in the category of sets as a framework for modeling discrete time systems. MTS can capture different types of system behaviors, but we focus on a combination of non-deterministic and probabilistic behaviors that often arises when modeling complex systems. Second, we use the category of posets and monotonic maps as a setting to define and compare approximations. In particular, for the MTS of interest, we consider approximations of their configurations based on complete lattices. Third, by restricting to finite lattices, we obtain algorithms that compute over-approximations, i.e., bounds from above within some partial order of approximants, of the system configuration after n steps. Interestingly, finite lattices of “interval probabilities” may fail to accurately approximate configurations that are both non-deterministic and probabilistic, even for deterministic (and continuous) system dynamics. However, better choices of finite lattices are available. © 2020 University of Szeged, Institute of Informatics. All rights reserved.

Place, publisher, year, edition, pages
Szeged: University of Szeged, Institute of Informatics, 2020
Keywords
Digital control systems, Discrete time control systems, Probability, Complete lattices, Discrete - time systems, Guaranteed bounds, Interval probability, Probabilistic behavior, System behaviors, System configurations, Transition system, Approximation algorithms
National Category
Control Engineering
Identifiers
urn:nbn:se:hh:diva-43653 (URN)10.14232/ACTACYB.24.3.2020.2 (DOI)000526957200002 ()2-s2.0-85085269748 (Scopus ID)
Funder
Knowledge FoundationELLIIT - The Linköping‐Lund Initiative on IT and Mobile Communications
Note

Additional funder: NSF CPS project. Grant number: 1136099

Available from: 2020-12-07 Created: 2020-12-07 Last updated: 2020-12-08Bibliographically approved
Chamberlain, R., Taha, W. & Törngren, M. (Eds.). (2019). Cyber Physical Systems. Model-Based Design: 8th International Workshop, CyPhy 2018, and 14th International Workshop, WESE 2018, Turin, Italy, October 4–5, 2018, Revised Selected Papers (1ed.). Cham: Springer
Open this publication in new window or tab >>Cyber Physical Systems. Model-Based Design: 8th International Workshop, CyPhy 2018, and 14th International Workshop, WESE 2018, Turin, Italy, October 4–5, 2018, Revised Selected Papers
2019 (English)Conference proceedings (editor) (Refereed)
Abstract [en]

This book constitutes the proceedings of the 8th International Workshop on Design, Modeling, and Evaluation of Cyber Physical Systems, CyPhy 2018 and 14th International Workshop on Embedded and Cyber-Physical Systems Education, WESE 2018, held in conjunction with ESWeek 2018, in Torino, Italy, in October 2018. The 13 full papers presented together  with 1 short paper in this volume were carefully reviewed and selected from 18 submissions. The conference presents a wide range of domains including Modeling, simulation, verification, design, cyber-physical systems, embedded systems, real-time systems, safety, and reliability. © 2019 Springer Nature Switzerland AG. Part of Springer Nature.

Place, publisher, year, edition, pages
Cham: Springer, 2019. p. 231 Edition: 1
Series
Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349 ; 11615
Keywords
Modeling, Simulation, Cyber-Physical Systems
National Category
Computer Sciences
Identifiers
urn:nbn:se:hh:diva-41303 (URN)10.1007/978-3-030-23703-5 (DOI)978-3-030-23703-5 (ISBN)978-3-030-23702-8 (ISBN)
Funder
Knowledge Foundation
Available from: 2019-12-24 Created: 2019-12-24 Last updated: 2020-01-15Bibliographically approved
Marchand, J., Puissochet, G., Lithén, T. & Taha, W. (2019). MicroITS: A scaled-down ITS platform. In: Lecture Notes in Computer Science: . Paper presented at 8th International Workshop on Design, Modeling, and Evaluation of Cyber Physical Systems, CyPhy 2018 and 14th International Workshop on Embedded and Cyber-Physical Systems Education, WESE 2018, held in conjunction with ESWeek 2018; Turin; Italy; 4 October 2018 through 5 October 2018 (pp. 214-221). Springer
Open this publication in new window or tab >>MicroITS: A scaled-down ITS platform
2019 (English)In: Lecture Notes in Computer Science, Springer, 2019, p. 214-221Conference paper, Published paper (Refereed)
Abstract [en]

Intelligent Transportation Systems (ITS) are an excellent illustration of the types of challenges that future technologists must address. In previous work we presented a course designed to engage students with theoretical aspects of embedded and cyber-physical systems. In this paper we present MicroITS, a platform addressing applied aspects. We articulate the design goals that we believe are needed to achieve engagement in an educational setting, and describe the platform and its baseline functionality. We briefly describe example projects that can be realized using MicroITS. Our hope is that this report will encourage the development of a community of educators and students interested in the use and the continued development of the platform. © Springer Nature Switzerland AG 2019.

Place, publisher, year, edition, pages
Springer, 2019
Series
Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349 ; 11615
Keywords
Cyber Physical System, Education computing, Intelligent systems, Intelligent vehicle highway systems, Students, Design goal, Educational settings, Intelligent transportation systems, Theoretical aspects, Embedded systems
National Category
Other Computer and Information Science
Identifiers
urn:nbn:se:hh:diva-41548 (URN)10.1007/978-3-030-23703-5_13 (DOI)2-s2.0-85069196047 (Scopus ID)9783030237028 (ISBN)
Conference
8th International Workshop on Design, Modeling, and Evaluation of Cyber Physical Systems, CyPhy 2018 and 14th International Workshop on Embedded and Cyber-Physical Systems Education, WESE 2018, held in conjunction with ESWeek 2018; Turin; Italy; 4 October 2018 through 5 October 2018
Funder
Knowledge Foundation
Available from: 2020-02-03 Created: 2020-02-03 Last updated: 2022-01-10Bibliographically approved
Moggi, E., Farjudian, A. & Taha, W. (2019). System analysis and robustness. In: CEUR Workshop Proceedings: Volume 2504. Paper presented at 20th Italian Conference on Theoretical Computer Science (ICTCS 2019), September 9-11, 2019 (pp. 1-7). CEUR-WS
Open this publication in new window or tab >>System analysis and robustness
2019 (English)In: CEUR Workshop Proceedings: Volume 2504, CEUR-WS , 2019, p. 1-7Conference paper, Published paper (Refereed)
Abstract [en]

Software is increasingly embedded in a variety of physical contexts. This imposes new requirements on tools that support the design and analysis of systems. For instance, modeling embedded and cyberphysical systems needs to blend discrete mathematics, which is suitable for modeling digital components, with continuous mathematics, used for modeling physical components. This blending of continuous and discrete creates challenges that are absent when the discrete or the continuous setting are considered in isolation. We consider robustness, that is, the ability of an analysis of a model to cope with small amounts of imprecision in the model. Formally, we identify analyses with monotonic maps between complete lattices (a mathematical framework used for abstract interpretation and static analysis) and define robustness for monotonic maps between complete lattices of closed subsets of a metric space. Copyright © 2019 for this paper by its authors.

Place, publisher, year, edition, pages
CEUR-WS, 2019
Series
CEUR Workshop Proceedings, ISSN 1613-0073 ; 2504
Keywords
Analyses, Domain theory, Robustness, Blending, Robustness (control systems), Static analysis, Abstract interpretations, Cyber physical systems (CPSs), Design and analysis, Discrete mathematics, Mathematical frameworks, Physical components, Embedded systems
National Category
Computer Systems
Identifiers
urn:nbn:se:hh:diva-41543 (URN)2-s2.0-85076003651 (Scopus ID)
Conference
20th Italian Conference on Theoretical Computer Science (ICTCS 2019), September 9-11, 2019
Available from: 2020-02-04 Created: 2020-02-04 Last updated: 2020-03-20Bibliographically approved
Moggi, E., Amin, F. & Taha, W. (2019). System Analysis and Robustness. In: Tiziana Margaria, Susanne Graf & Kim G. Larsen (Ed.), Tiziana Margaria, Susanne Graf & Kim G. Larsen (Ed.), Models, Mindsets, Meta: The What, the How, and the Why Not?: Essays Dedicated to Bernhard Steffen on the Occasion of His 60th Birthday (pp. 36-44). Cham: Springer
Open this publication in new window or tab >>System Analysis and Robustness
2019 (English)In: Models, Mindsets, Meta: The What, the How, and the Why Not?: Essays Dedicated to Bernhard Steffen on the Occasion of His 60th Birthday / [ed] Tiziana Margaria, Susanne Graf & Kim G. Larsen, Cham: Springer, 2019, p. 36-44Conference paper, Published paper (Refereed)
Abstract [en]

Software is increasingly embedded in a variety of physical contexts. This imposes new requirements on tools that support the design and analysis of systems. For instance, modeling embedded and cyber-physical systems needs to blend discrete mathematics, which is suitable for modeling digital components, with continuous mathematics, used for modeling physical components. This blending of continuous and discrete creates challenges that are absent when the discrete or the continuous setting are considered in isolation. We consider robustness, that is, the ability of an analysis of a model to cope with small amounts of imprecision in the model. Formally, we identify analyses with monotonic maps between complete lattices (a mathematical framework used for abstract interpretation and static analysis) and define robustness for monotonic maps between complete lattices of closed subsets of a metric space. © Springer Nature Switzerland AG 2019

Place, publisher, year, edition, pages
Cham: Springer, 2019
Series
Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349 ; 11200
Keywords
Modeling, Simulation, Hybrid Systems, Cyber-Physical Systems
National Category
Computer Sciences
Identifiers
urn:nbn:se:hh:diva-41304 (URN)10.1007/978-3-030-22348-9_4 (DOI)2-s2.0-85067949429 (Scopus ID)978-3-030-22347-2 (ISBN)978-3-030-22348-9 (ISBN)
Note

Also part of the Theoretical Computer Science and General Issues book sub series (LNTCS, volume 11200)

Available from: 2019-12-24 Created: 2019-12-24 Last updated: 2020-03-25Bibliographically approved
Duracz, A., Moggi, E., Taha, W. & Lin, Z. (2018). A Semantic Account of Rigorous Simulation. In: Marten LohstrohPatricia DerlerMarjan Sirjani (Ed.), Principles of Modeling: Essays Dedicated to Edward A. Lee on the Occasion of His 60th Birthday (pp. 223-239). Amsterdam: Springer Berlin/Heidelberg, 10760
Open this publication in new window or tab >>A Semantic Account of Rigorous Simulation
2018 (English)In: Principles of Modeling: Essays Dedicated to Edward A. Lee on the Occasion of His 60th Birthday / [ed] Marten LohstrohPatricia DerlerMarjan Sirjani, Amsterdam: Springer Berlin/Heidelberg, 2018, Vol. 10760, p. 223-239Chapter in book (Refereed)
Abstract [en]

Hybrid systems are a powerful formalism for modeling cyber-physical systems. Reachability analysis is a general method for checking safety properties, especially in the presence of uncertainty and non-determinism. Rigorous simulation is a convenient tool for reachability analysis of hybrid systems. However, to serve as proof tool, a rigorous simulator must be correct w.r.t. a clearly defined notion of reachability, which captures what is intuitively reachable in finite time. As a step towards addressing this challenge, this paper presents a rigorous simulator in the form of an operational semantics and a specification in the form of a denotational semantics. We show that, under certain conditions about the representation of enclosures, the rigorous simulator is correct. We also show that finding a representation satisfying these assumptions is non-trivial. © 2018, Springer International Publishing AG, part of Springer Nature.

Place, publisher, year, edition, pages
Amsterdam: Springer Berlin/Heidelberg, 2018
Series
Lecture Notes In Computer Science, ISSN 0302-9743, E-ISSN 1611-3349 ; 10760
Keywords
Correctness, Programming languages, Reachability analysis, Computer programming languages, Embedded systems, Hybrid systems, Semantics, Simulators, Denotational semantics, General method, Non Determinism, Operational semantics, Rigorous simulation, Safety property, Uncertainty analysis
National Category
Computer Systems Embedded Systems
Identifiers
urn:nbn:se:hh:diva-38736 (URN)10.1007/978-3-319-95246-8_13 (DOI)2-s2.0-85052713247 (Scopus ID)978-3-319-95245-1 (ISBN)978-3-319-95246-8 (ISBN)
Available from: 2019-01-09 Created: 2019-01-09 Last updated: 2019-01-09Bibliographically approved
Taha, W. (2018). Rigorous simulation. In: Salem, A., Abbas, H. M., Elkharashi, M. W., Eldin, A. M. B., Taher, M., Zaki, A. M. (Ed.), : . Paper presented at 13th International Conference on Computer Engineering and Systems (ICCES 2018) (pp. XXIII-XXIV). Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>Rigorous simulation
2018 (English)In: / [ed] Salem, A., Abbas, H. M., Elkharashi, M. W., Eldin, A. M. B., Taher, M., Zaki, A. M., Institute of Electrical and Electronics Engineers (IEEE), 2018, p. XXIII-XXIVConference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2018
National Category
Computer Sciences
Identifiers
urn:nbn:se:hh:diva-41503 (URN)000465792300002 ()
Conference
13th International Conference on Computer Engineering and Systems (ICCES 2018)
Available from: 2020-02-03 Created: 2020-02-03 Last updated: 2020-02-03Bibliographically approved
Moggi, E., Farjudian, A., Duracz, A. & Taha, W. (2018). Safe & robust reachability analysis of hybrid systems. Theoretical Computer Science, 747, 75-99
Open this publication in new window or tab >>Safe & robust reachability analysis of hybrid systems
2018 (English)In: Theoretical Computer Science, ISSN 0304-3975, E-ISSN 1879-2294, Vol. 747, p. 75-99Article in journal (Refereed) Published
Abstract [en]

Hybrid systems—more precisely, their mathematical models—can exhibit behaviors, like Zeno behaviors, that are absent in purely discrete or purely continuous systems. First, we observe that, in this context, the usual definition of reachability—namely, the reflexive and transitive closure of a transition relation—can be unsafe, i.e., it may compute a proper subset of the set of states reachable in finite time from a set of initial states. Therefore, we propose safe reachability, which always computes a superset of the set of reachable states. Second, in safety analysis of hybrid and continuous systems, it is important to ensure that a reachability analysis is also robust w.r.t. small perturbations to the set of initial states and to the system itself, since discrepancies between a system and its mathematical models are unavoidable. We show that, under certain conditions, the best Scott continuous approximation of an analysis A is also its best robust approximation. Finally, we exemplify the gap between the set of reachable states and the supersets computed by safe reachability and its best robust approximation. © 2018 The Authors

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2018
Keywords
Computational methods, Computer science, Robustness (control systems), Continuous approximations, Domain theory, Reachability, Reachability analysis, Robust approximations, Small perturbations, Transition relations, Transitive closure, Hybrid systems
National Category
Control Engineering Computational Mathematics Embedded Systems
Identifiers
urn:nbn:se:hh:diva-38699 (URN)10.1016/j.tcs.2018.06.020 (DOI)000447571900005 ()2-s2.0-85048949865 (Scopus ID)
Funder
Knowledge FoundationELLIIT - The Linköping‐Lund Initiative on IT and Mobile Communications
Note

Funding: US NSF Grant number: 1736759

Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-01-08Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-3160-9188

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