Browsing by Author "Garro, Alfredo"

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Distribution, Reuse and Interoperability of simulation models in heterogeneous distributed computing environments
(2017-07-26) Falcone, Alberto; Garro, Alfredo; Crupi, Felice
Modeling and Simulation (M&S) is gaining a central role in several industrial domains such as automotive, e-science and aerospace, due to the increasing complexity of system requirements and thus of the related engineering problems. Specifically, M&S methods, tools, and techniques can e↵ectively support the analysis and design of modern systems by enabling the evaluation and comparison of di↵erent design choices against requirements through virtual testing; this opportunity becomes even crucial when complete and actual tests are too expensive to be performed in terms of cost, time and other resources. Moreover, as systems result from the integration of components which are often designed and manufactured by di↵erent organizations belonging to di↵erent engineering domains (including mechanical, electrical, control, and software), great benefits can derive from the possibility to perform simulations which involve components independently developed and running on di↵erent and possibly geographically distributed machines. Indeed, distributed simulation promotes an e↵ective cooperative, integrated and concurrent approach to complex systems analysis and design. Although M&S o↵ers many advantages related to the possibility of doing controlled experiments on an artificial representation of a system, its practical use requires to face with important issues such as, (i) difficulties to reuse simulation models already made; (ii) lack of rules and procedures by which to make interoperable models created with di↵erent simulation environments; and, (iii) lack of mechanisms for executing simulation models in distributed and heterogeneous environments. Indeed, there are di↵erent simulation environments both commercial and noncommercial highly specialized that allow the design and implementation of simulation models in specific domains. However, a single simulation environment is not able to manage all the necessary aspects to model a system when it is composed of several components. Typically, the modeling and simulation of such systems, whose behavior cannot be straightforwardly defined, derived and easily analyzed starting from the behavior of their components, require to identify and face with some important research issues.
Model-based and simulation-driven methods for the reliability and safety analysis of systems
(2013-11-28) Tundis, Andrea; Greco, Sergio; Garro, Alfredo
In several industrial domains such as automotive, railway, avionics, satellite, health care and energy, a great variety of systems are currently designed and developed by organizing and integrating existing components (which in turn can be regarded as systems),that pool their resources and capabilities together to create a new system which is able to o er more functionalities and performances than those o ered by the simple sum of its components. Typically, the design and management of such systems, whose properties cannot be immediately de ned, derived and easily analyzed starting from the properties of their parts when they are considered in stand-alone, require to identify and face with some important research issues. In particular, the integration of system components is a challenging task whose criticality rises as the heterogeneity and complexity of the components increase. Thus, suitable engineering methods, tools and techniques need to be exploited to prevent and manage the risks arising from the integration of system components and, mainly, to avoid their occurrence in the advanced phases of the system development process which may result in a signi cant increase in the entire project costs. To overcome these issues the adoption of the Systems Engineering approach represents a viable solution as it provides a wide set of methods and practices which allow the de nition of the system architecture and behavior at di erent abstraction level in terms of its components and their interactions. Moreover, systems requirements are constantly traced during the di erent system development phases so to clearly specify how a system component concurs to the ful llment of the requirements. However, in the Systems Engineering eld, even though great attention has been devoted to functional requirements analysis and traceability, there is still a lack of methods which speci cally address these issues for non-functional requirements. As a consequence, the analysis concerning if and how non-functional requirements are met by the system under development is not typically executed contextually to the design of the system but still postponed to the last stages of the development process with a high risk of having to revise even basic design choices and with a consequent increase in both completion tim and development costs. Among all system requirements, Reliability and Safety are important non-functional requirements. Especially for mission-critical systems, there is a strong demand for new and more powerful analysis tools and techniques able not only to verify the reliability indices and safety of a system but also to exibly evaluate the system performances and compare di erent design choices. In this context, the research aimed to promote the use of exible methods for the analysis of non-functional requirements by focusing on the de nition of: (i) model-based method for system reliability analysis centered on popular SysML/UML-based languages for systems modeling and on de-facto standard platforms for the simulation of multi-domain dynamic and embedded systems (Mathworks Simulink); (ii) a methodological process for supporting the safety analysis, along with an approach for performing the Fault Tree Analysis of cyber-physical systems, mainly based on the Modelica language and OpenModelica simulation environment. Furthermore, in order to support the representation of system requirements and thus enable their veri cation and validation during the design stages, a meta-model for modeling requirements of physical systems as well as di erent approaches for extending the Modelica language have been proposed. Moreover, an algorithm, which allows trace and evaluate requirements violation through simulation, has been de ned. Finally, the e ectiveness of the proposed methods and approaches, especially in the modeling and analysis of both the expected and dysfunctional system behavior, is the result of an intensive experimentation in several industrial domains such automotive, avionics and satellite
Requirements engineering for complex systems
(2017-07-26) Gallo, Teresa; Saccà, Domenico; Furfaro, Angelo; Garro, Alfredo; Crupi, Felice
Requirements Engineering (RE) is a part of Software Engineering and, in general, of System Engineering. RE aims to help in building software which satis es the user needs, eliciting, documenting, validating and maintaining the requirements that a software has to adequately satisfy. During its 30 years of RE history, its importance has been perceived with various degrees, from being the most important activity, well formalized and de ned in big complete documents which were the bible of the software project, to the opposite side where it has been reduced to just an informal activity, volatile, never formalized, not at all maintained, because ever changing. The need for well managing requirements is extremely important, mainly for complex systems which involve great investments of resources and/or cannot be easily substituted. A system can be complex because it is realized by the collaboration of a numerous and heterogeneous set of stakeholders, as for example in a big industrial research project, often co-funded with public resources, where usually many partners, with di erent backgrounds and languages must cooperate for reaching the project goals. Furthermore, a system can be complex because it constitutes the IT system of an Enterprise, which has been grown, along the time, by adding many pieces of software, integrated in many and di erent ways; the IT system is often distributed, ubiquitously interoperates on many computers, and behaves as a whole big system, though developed by many software providers, at di erent times, with di erent technologies and tools. The complexity of these systems is highly considered for several critical industrial domains where features of real-time and fault-tolerance are vital, such as automotive, railway, avionics, satellite, health care and energy; in these domains a great variety of systems are usually designed and developed by organizing and integrating existing components that pool their resources and capabilities to create a new system which is able to o er more functionalities and performances than those o ered by the simple sum of its components. Typically, the design and management of such systems, best known as System of Systems (SoS), have properties not immediately de ned, derived and easily analyzed starting from the properties of their stand-alone parts. For these reasons, SoS requires suitably engineered methods, tools and techniques, for managing requirements and any other construction process phase, with the aim to minimize whichever risk of fail. However, every complex IT system, even though it does not deal with a critical domain, but it supports the core business of an enterprise, must be well governed to avoid the risk of becoming rapidly inadequate to its role. This risk becomes high when many uncontrolled IT developments, aimed at supporting requirements changes, accumulate. In fact, as the complexity grows up, the IT system might become too expensive to maintain and then it should be retired and substituted after some too short time, often with big and underestimated di culties. For these reasons, complex systems must be governed during their evolution, both from the point of view of 'which application is where and why', and from the point of view of the supported requirements, that is 'which need is supported by each application and for whom'. This governance would facilitate the knowledge, the management, the essentialness and the maintenance of the complex systems, by allowing e cient support and a long-lasting system, with the consequence of minimizing waste of costs and inadequacy of the support for core business of the enterprise. This work addresses mainly the issue of governing systems which are complex because either they are the result of the collaboration of many di erent stakeholders (e.g. are big co-funded R&D projects) or they are Enterprise Information Systems (EIS) (e.g. IT system of medium/large enterprises). In this direction, a new goal-oriented requirements methodology, named GOReM, was de ned which has speci c features useful for the addressed issues. In addition a new approach, ResDevOps, has been conceived, that allows to re ne the government of the requirements of an EIS which is continuously improved, and which increases and evolves along the time. The thesis presents the framework of state of the art in which these activities found their collocation, together with a set of case studies which were developed inside some real projects, mainly big projects of R&D which have seen involved the University of Calabria, but also some cases in real industrial projects. The main results were published and were included in international conference proceedings and a manuscript is in press on an international journal.