672 research outputs found
Business Process Simulation: A Systematic Literature Review
Business process simulation marks an essential Business Process Management technique for analysing business processes and for reasoning about process improvement. Despite its importance, literature is lacking a comprehensive, updated overview of research contributions to the field of business process simulation. In this systematic literature review, we assess the present state of research on business process simulation including prior work between 1990 and 2016. Results reported in the present study assist in advancing the discussion on future research on business process simulation by compiling and analysing prior work. The present literature review focuses on prior research involving conceptual business process models, e.g., BPMN models, with a graphical model representation as a starting point for business process simulation and excludes other foundations to build simulation models
Engineering framework for service-oriented automation systems
Tese de doutoramento. Engenharia InformĂĄtica. Universidade do Porto. Faculdade de Engenharia. 201
Executable system architecting using systems modeling language in conjunction with Colored Petri Nets - a demonstration using the GEOSS network centric system
Models and simulation furnish abstractions to manage complexities allowing engineers to visualize the proposed system and to analyze and validate system behavior before constructing it. Unified Modeling Language (UML) and its systems engineering extension, Systems Modeling Language (SysML), provide a rich set of diagrams for systems specification. However, the lack of executable semantics of such notations limits the capability of analyzing and verifying defined specifications. This research has developed an executable system architecting framework based on SysML-CPN transformation, which introduces dynamic model analysis into SysML modeling by mapping SysML notations to Colored Petri Net (CPN), a graphical language for system design, specification, simulation, and verification. A graphic user interface was also integrated into the CPN model to enhance the model-based simulation. A set of methodologies has been developed to achieve this framework. The aim is to investigate system wide properties of the proposed system, which in turn provides a basis for system reconfiguration --Abstract, page iii
An agile and adaptive holonic architecture for manufacturing control
Tese de doutoramento. Engenharia Electrotécnica e de Computadores. 2004. Faculdade de Engenharia. Universidade do Port
Evaluating Resilience of Cyber-Physical-Social Systems
Nowadays, protecting the network is not the only security concern. Still, in cyber security,
websites and servers are becoming more popular as targets due to the ease with which
they can be accessed when compared to communication networks. Another threat in
cyber physical social systems with human interactions is that they can be attacked and
manipulated not only by technical hacking through networks, but also by manipulating
people and stealing usersâ credentials. Therefore, systems should be evaluated beyond cy-
ber security, which means measuring their resilience as a piece of evidence that a system
works properly under cyber-attacks or incidents. In that way, cyber resilience is increas-
ingly discussed and described as the capacity of a system to maintain state awareness for
detecting cyber-attacks. All the tasks for making a system resilient should proactively
maintain a safe level of operational normalcy through rapid system reconfiguration to
detect attacks that would impact system performance. In this work, we broadly studied
a new paradigm of cyber physical social systems and defined a uniform definition of it.
To overcome the complexity of evaluating cyber resilience, especially in these inhomo-
geneous systems, we proposed a framework including applying Attack Tree refinements
and Hierarchical Timed Coloured Petri Nets to model intruder and defender behaviors
and evaluate the impact of each action on the behavior and performance of the system.Hoje em dia, proteger a rede nĂŁo Ă© a Ășnica preocupação de segurança. Ainda assim, na
segurança cibernética, sites e servidores estão se tornando mais populares como alvos
devido Ă facilidade com que podem ser acessados quando comparados Ă s redes de comu-
nicação. Outra ameaça em sistemas sociais ciberfisicos com interaçÔes humanas é que eles
podem ser atacados e manipulados não apenas por hackers técnicos através de redes, mas
também pela manipulação de pessoas e roubo de credenciais de utilizadores. Portanto, os
sistemas devem ser avaliados para além da segurança cibernética, o que significa medir
sua resiliĂȘncia como uma evidĂȘncia de que um sistema funciona adequadamente sob
ataques ou incidentes cibernĂ©ticos. Dessa forma, a resiliĂȘncia cibernĂ©tica Ă© cada vez mais
discutida e descrita como a capacidade de um sistema manter a consciĂȘncia do estado para
detectar ataques cibernéticos. Todas as tarefas para tornar um sistema resiliente devem
manter proativamente um nĂvel seguro de normalidade operacional por meio da reconfi-
guração råpida do sistema para detectar ataques que afetariam o desempenho do sistema.
Neste trabalho, um novo paradigma de sistemas sociais ciberfisicos Ă© amplamente estu-
dado e uma definição uniforme é proposta. Para superar a complexidade de avaliar a
resiliĂȘncia cibernĂ©tica, especialmente nesses sistemas nĂŁo homogĂ©neos, Ă© proposta uma
estrutura que inclui a aplicação de refinamentos de Ărvores de Ataque e Redes de Petri
Coloridas Temporizadas HierĂĄrquicas para modelar comportamentos de invasores e de-
fensores e avaliar o impacto de cada ação no comportamento e desempenho do sistema
The Impact of Petri Nets on System-of-Systems Engineering
The successful engineering of a large-scale system-of-systems project towards deterministic behaviour depends on integrating autonomous components using international communications standards in accordance with dynamic requirements. To-date, their engineering has been unsuccessful: no combination of top-down and bottom-up engineering perspectives is adopted, and information exchange protocol and interfaces between components are not being precisely specified. Various approaches such as modelling, and architecture frameworks make positive contributions to system-of-systems specification but their successful implementation is still a problem.
One of the most popular modelling notations available for specifying systems, UML, is intuitive and graphical but also ambiguous and imprecise. Supplying a range of diagrams to represent a system under development, UML lacks simulation and exhaustive verification capability. This shortfall in UML has received little attention in the context of system-of-systems and there are two major research issues:
1. Where the dynamic, behavioural diagrams of UML can and cannot be used to model and analyse system-of-systems
2. Determining how Petri nets can be used to improve the specification and analysis of the dynamic model of a system-of-systems specified using UML
This thesis presents the strengths and weaknesses of Petri nets in relation to the specification of system-of-systems and shows how Petri net models can be used instead of conventional UML Activity Diagrams. The model of the system-of-systems can then be analysed and verified using Petri net theory. The Petri net formalism of behaviour is demonstrated using two case studies from the military domain. The first case study uses Petri nets to specify and analyse a close air support mission. This case study concludes by indicating the strengths, weaknesses, and shortfalls of the proposed formalism in system-of-systems specification. The second case study considers specification of a military exchange network parameters problem and the results are compared with the strengths and weaknesses identified in the first case study.
Finally, the results of the research are formulated in the form of a Petri net enhancement to UML (mapping existing activity diagram elements to Petri net elements) to meet the needs of system-of-systems specification, verification and validation
Ninth Workshop and Tutorial on Practical Use of Coloured Petri Nets and the CPN Tools, Aarhus, Denmark, October 20-22, 2008
This booklet contains the proceedings of the Ninth Workshop on Practical Use of Coloured Petri Nets and the CPN Tools, October 20-22, 2008. The workshop is organised by the CPN group at the Department of Computer Science, University of Aarhus, Denmark. The papers are also available in electronic form via the web pages: http://www.daimi.au.dk/CPnets/workshop0
Applications of Bayesian networks and Petri nets in safety, reliability, and risk assessments: A review
YesSystem safety, reliability and risk analysis are important tasks that are performed throughout the system lifecycle to ensure the dependability of safety-critical systems. Probabilistic risk assessment (PRA) approaches
are comprehensive, structured and logical methods widely used for this purpose. PRA approaches include,
but not limited to, Fault Tree Analysis (FTA), Failure Mode and Effects Analysis (FMEA), and Event
Tree Analysis (ETA). Growing complexity of modern systems and their capability of behaving dynamically
make it challenging for classical PRA techniques to analyse such systems accurately. For a comprehensive
and accurate analysis of complex systems, different characteristics such as functional dependencies among
components, temporal behaviour of systems, multiple failure modes/states for components/systems, and
uncertainty in system behaviour and failure data are needed to be considered. Unfortunately, classical
approaches are not capable of accounting for these aspects. Bayesian networks (BNs) have gained popularity
in risk assessment applications due to their flexible structure and capability of incorporating most of the
above mentioned aspects during analysis. Furthermore, BNs have the ability to perform diagnostic analysis.
Petri Nets are another formal graphical and mathematical tool capable of modelling and analysing dynamic
behaviour of systems. They are also increasingly used for system safety, reliability and risk evaluation. This
paper presents a review of the applications of Bayesian networks and Petri nets in system safety, reliability
and risk assessments. The review highlights the potential usefulness of the BN and PN based approaches over
other classical approaches, and relative strengths and weaknesses in different practical application scenarios.This work was funded by the DEIS H2020 project (Grant Agreement 732242)
Proceedings of International Workshop "Global Computing: Programming Environments, Languages, Security and Analysis of Systems"
According to the IST/ FET proactive initiative on GLOBAL COMPUTING, the goal is to obtain techniques (models, frameworks, methods, algorithms) for constructing systems that are flexible, dependable, secure, robust and efficient.
The dominant concerns are not those of representing and manipulating data efficiently but rather those of handling the co-ordination and interaction, security, reliability, robustness, failure modes, and control of risk of the entities in the system and the overall design, description and performance of the system itself.
Completely different paradigms of computer science may have to be developed to tackle these issues effectively. The research should concentrate on systems having the following characteristics: âą The systems are composed of autonomous computational entities where activity is not centrally controlled, either because global control is impossible or impractical, or because the entities are created or controlled by different owners.
âą The computational entities are mobile, due to the movement of the physical platforms or by movement of the entity from one platform to another.
âą The configuration varies over time. For instance, the system is open to the introduction of new computational entities and likewise their deletion.
The behaviour of the entities may vary over time.
âą The systems operate with incomplete information about the environment.
For instance, information becomes rapidly out of date and mobility requires information about the environment to be discovered.
The ultimate goal of the research action is to provide a solid scientific foundation for the design of such systems, and to lay the groundwork for achieving effective principles for building and analysing such systems.
This workshop covers the aspects related to languages and programming environments as well as analysis of systems and resources involving 9 projects (AGILE , DART, DEGAS , MIKADO, MRG, MYTHS, PEPITO, PROFUNDIS, SECURE) out of the 13 founded under the initiative. After an year from the start of the projects, the goal of the workshop is to fix the state of the art on the topics covered by the two clusters related to programming environments and analysis of systems as well as to devise strategies and new ideas to profitably continue the research effort towards the overall objective of the initiative.
We acknowledge the Dipartimento di Informatica and Tlc of the University of Trento, the Comune di Rovereto, the project DEGAS for partially funding the event and the Events and Meetings Office of the University of Trento for the valuable collaboration
Software Perfomance Assessment at Architectural Level: A Methodology and its Application
Las arquitecturas software son una valiosa herramienta para la evaluaciĂłn de las propiedades cualitativas y cuantitativas de los sistemas en sus primeras fases de desarrollo. Conseguir el diseño adecuado es crĂtico para asegurar la bondad de dichas propiedades. Tomar decisiones tempranas equivocadas puede implicar considerables y costosos cambios en un futuro. Dichas decisiones afectarĂan a muchas propiedades del sistema, tales como su rendimiento, seguridad, fiabilidad o facilidad de mantenimiento. Desde el punto de vista del rendimiento software, la ingenierĂa del rendimiento del software (SPE) es una disciplina de investigaciĂłn madura y comĂșnmente aceptada que propone una evaluaciĂłn basada en modelos en las primeras fases del ciclo de vida de desarrollo software. Un problema en este campo de investigaciĂłn es que las metodologĂas hasta ahora propuestas no ofrecen una interpretaciĂłn de los resultados obtenidos durante el anĂĄlisis del rendimiento, ni utilizan dichos resultados para proponer alternativas para la mejora de la propia arquitectura software. Hasta la fecha, esta interpretaciĂłn y mejora requiere de la experiencia y pericia de los ingenieros software, en especial de expertos en ingenierĂa de prestaciones. AdemĂĄs, a pesar del gran nĂșmero de propuestas para evaluar el rendimiento de sistemas software, muy pocos de estos estudios teĂłricos son posteriormente aplicados a sistemas software reales. El objetivo de esta tesis es presentar una metodologĂa para el asesoramiento de decisiones arquitecturales para la mejora, desde el punto de vista de las prestaciones, de las sistemas software. La metodologĂa hace uso del Lenguaje Unificado de Modelado (UML) para representar las arquitecturas software y de mĂ©todos formales, concretamente redes de Petri, como modelo de prestaciones. El asesoramiento, basado en patrones y antipatrones, intenta detectar los principales problemas que afectan a las prestaciones del sistema y propone posibles mejoras para mejoras dichas prestaciones. Como primer paso, estudiamos y analizamos los resultados del rendimiento de diferentes estilos arquitectĂłnicos. A continuaciĂłn, sistematizamos los conocimientos previamente obtenidos para proponer una metodologĂa y comprobamos su aplicabilidad asesorando un caso de estudio real, una arquitectura de interoperabilidad para adaptar interfaces a personas con discapacidad conforme a sus capacidades y preferencias. Finalmente, se presenta una herramienta para la evaluaciĂłn del rendimiento como un producto derivado del propio ciclo de vida software
- âŠ