231 research outputs found
Virtual Communication Stack: Towards Building Integrated Simulator of Mobile Ad Hoc Network-based Infrastructure for Disaster Response Scenarios
Responses to disastrous events are a challenging problem, because of possible
damages on communication infrastructures. For instance, after a natural
disaster, infrastructures might be entirely destroyed. Different network
paradigms were proposed in the literature in order to deploy adhoc network, and
allow dealing with the lack of communications. However, all these solutions
focus only on the performance of the network itself, without taking into
account the specificities and heterogeneity of the components which use it.
This comes from the difficulty to integrate models with different levels of
abstraction. Consequently, verification and validation of adhoc protocols
cannot guarantee that the different systems will work as expected in
operational conditions. However, the DEVS theory provides some mechanisms to
allow integration of models with different natures. This paper proposes an
integrated simulation architecture based on DEVS which improves the accuracy of
ad hoc infrastructure simulators in the case of disaster response scenarios.Comment: Preprint. Unpublishe
Extending the DEVS Formalism with Initialization Information
DEVS is a popular formalism to model system behaviour using a discrete-event
abstraction. The main advantages of DEVS are its rigourous and precise
specification, as well as its support for modular, hierarchical construction of
models. DEVS frequently serves as a simulation "assembly language" to which
models in other formalisms are translated, either giving meaning to new
(domain-specific) languages, or reproducing semantics of existing languages.
Despite this rigourous definition of its syntax and semantics, initialization
of DEVS models is left unspecified in both the Classic and Parallel DEVS
formalism definition. In this paper, we extend the DEVS formalism by including
an initial total state. Extensions to syntax as well as denotational (closure
under coupling) and operational semantics (abstract simulator) are presented.
The extension is applicable to both main variants of the DEVS formalism. Our
extension is such that it adds to, but does not alter the original
specification. All changes are illustrated by means of a traffic light example
The DEVStone Metric: Performance Analysis of DEVS Simulation Engines
The DEVStone benchmark allows us to evaluate the performance of
discrete-event simulators based on the DEVS formalism. It provides model sets
with different characteristics, enabling the analysis of specific issues of
simulation engines. However, this heterogeneity hinders the comparison of the
results among studies, as the results obtained on each research work depend on
the chosen subset of DEVStone models. We define the DEVStone metric based on
the DEVStone synthetic benchmark and provide a mechanism for specifying
objective ratings for DEVS-based simulators. This metric corresponds to the
average number of times that a simulator can execute a selection of 12 DEVStone
models in one minute. The variety of the chosen models ensures we measure
different particularities provided by DEVStone. The proposed metric allows us
to compare various simulators and to assess the impact of new features on their
performance. We use the DEVStone metric to compare some popular DEVS-based
simulators
Understanding the Elements of Executable Architectures Through a Multi-Dimensional Analysis Framework
The objective of this dissertation study is to conduct a holistic investigation into the elements of executable architectures. Current research in the field of Executable Architectures has provided valuable solution-specific demonstrations and has also shown the value derived from such an endeavor. However, a common theory underlying their applications has been missing.
This dissertation develops and explores a method for holistically developing an Executable Architecture Specification (EAS), i.e., a meta-model containing both semantic and syntactic information, using a conceptual framework for guiding data coding, analysis, and validation. Utilization of this method resulted in the description of the elements of executable architecture in terms of a set of nine information interrogatives: an executable architecture information ontology. Once the detail-rich EAS was constructed with this ontology, it became possible to define the potential elements of executable architecture through an intermediate level meta-model. The intermediate level meta-model was further refined into an interrogative level meta-model using only the nine information interrogatives, at a very high level of abstraction
Toward composing variable structure models and their interfaces: a case of intensional coupling definitions
In this thesis, we investigate a combination of traditional component-based and variable structure modeling. The focus is on a structural consistent specification of couplings in modular, hierarchical models with a variable structure. For this, we exploitintensional definitions, as known from logic, and introduce a novel intensional coupling definition, which allows a concise yet expressive specification of complex communication and interaction patterns in static as well as variable structure models, without the need to worryabout structural consistency.In der Arbeit untersuchen wir ein Zusammenbringen von klassischer komponenten-basierter und variabler Strukturmodellierung. Der Fokus liegt dabei auf der Spezifikation von strukturkonsistenten Kopplungen in modular-hierarchischen Modellen mit einer variablen Struktur. DafĂĽr nutzen wir intensionale Definitionen, wie sie aus der Logik bekannt sind, und fĂĽhren ein neuartiges Konzept von intensionalen Kopplungen ein, welches kompakte gleichzeitig ausdrucksstarke Spezifikationen von komplexen Kommunikations- und Interaktionsmuster in statischen und variablen Strukturmodellen erlaubt
Executable Architecture Research at Old Dominion University
Executable Architectures allow the evaluation of system architectures not only regarding their static, but also their dynamic behavior. However, the systems engineering community do not agree on a common formal specification of executable architectures. To close this gap and identify necessary elements of an executable architecture, a modeling language, and a modeling formalism is topic of ongoing PhD research. In addition, systems are generally defined and applied in an operational context to provide capabilities and enable missions. To maximize the benefits of executable architectures, a second PhD effort introduces the idea of creating an executable context in addition to the executable architecture. The results move the validation of architectures from the current information domain into the knowledge domain and improve the reliability of such validation efforts. The paper presents research and results of both doctoral research efforts and puts them into a common context of state-of-the-art of systems engineering methods supporting more agility
xDEVS: A toolkit for interoperable modeling and simulation of formal discrete event systems
Employing Modeling and Simulation (M&S) extensively to analyze and develop complex systems is the norm today. The use of robust M&S formalisms and rigorous methodologies is essential to deal with complexity. Among them, the Discrete Event System Specification (DEVS) provides a solid framework for modeling structural, behavior and information aspects of any complex system. This gives several advantages to analyze and design complex systems: completeness, verifiability, extensibility, and maintainability. DEVS formalism has been implemented in many programming languages and executable on multiple platforms. In this paper, we describe the features of an M&S framework called xDEVS that builds upon the prevalent DEVS Application Programming Interface (API) for both modeling and simulation layers, promoting interoperability between the existing platform-specific (C++, Java, Python) DEVS implementations. Additionally, the framework can simulate the same model using sequential, parallel, or distributed architectures. The M&S engine has been reinforced with several strategies to improve performance, as well as tools to perform model analysis and verification. Finally, xDEVS also facilitates systems engineers to apply the vision of model-based systems engineering (MBSE), model-driven engineering (MDE), and model-driven systems engineering (MDSE) paradigms. We highlight the features of the proposed xDEVS framework with multiple examples and case studies illustrating the rigor and diversity of application domains it can support
An Object-Oriented Framework for Designing Reusable and Maintainable DEVS Models using Design Patterns
Design patterns are well practices to share software development experiences.
These patterns allow enhancing reusability, readability and maintainability of
architecture and code of software applications. As simulation applies
computerized models to produce traces in order to obtain results and
conclusions, designers of simulation explored design patterns to make the
simulation code more reusable, more readable and easy to maintain, in addition
to design complex software oriented simulation modeling.
In DEVS (Discrete Event System specification), the designers have
successfully designed simulations, frameworks, tools, etc. However, some issues
remain still open and should be explored like how a piece of code that
implements a set of states, events and transitions may be reused to design a
new DEVS model? How may a DEVS model be extended to a new formalism? Etc.
In this paper, we address these issues and we propose a set of patterns that
may serve as guidelines to designers of DEVS models and its extensions and may
contribute to the design of an operational simulation framework. These patterns
are inspired partly by the available designs of DEVS community and software
engineering developers
An Extended Interoperability Framework for Joint Composability
Interoperation of systems is defined by the aspects of integratability, interoperability, and composability. It is therefore needed, to address all levels of interoperation - from conceptual models via implemented systems to the supported infrastructure - accordingly in an interoperation framework.
Several candidates are available and provide valuable part solution. This paper evaluates the Base Object Models (BOMs), Discrete Event Simulation Specifications (DEVS), Unified Language Model (UML) artifacts as used within the Test and Training Enabling Architecture (TENA), the Object-Process Methodology (OPM), and Conceptual Graphs (CG) regarding their contribution.
Using the Levels of Conceptual Interoperability Model (LCIM), an extended interoperability framework based on the contributions of BOM, DEVS, UML/TENA, OPM, and CG will be proposed and gaps in support of joint composability are indentified
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