90 research outputs found
Carbon nanotubes based transistors composed of single-walled carbon nanotubes mats as gas sensors: A review
A template-based methodology for the specification and automated composition of performability models
Dependability and performance analysis of modern systems is facing great challenges: their scale is growing, they are becoming massively distributed, interconnected, and evolving. Such complexity makes model-based assessment a difficult and time-consuming task. For the evaluation of large systems, reusable submodels are typically adopted as an effective way to address the complexity and to improve the maintainability of models. When using state-based models, a common approach is to define libraries of generic submodels, and then compose concrete instances by state sharing, following predefined “patterns” that depend on the class of systems being modeled. However, such composition patterns are rarely formalized, or not even documented at all. In this paper, we address this problem using a model-driven approach, which combines a language to specify reusable submodels and composition patterns, and an automated composition algorithm. Clearly defining libraries of reusable submodels, together with patterns for their composition, allows complex models to be automatically assembled, based on a high-level description of the scenario to be evaluated. This paper provides a solution to this problem focusing on: formally defining the concept of model templates, defining a specification language for model templates, defining an automated instantiation and composition algorithm, and applying the approach to a case study of a large-scale distributed system69129330
Stochastic Activity Networks Templates: Supporting Variability in Performability Models
Model-based evaluation is extensively used to estimate performance and
reliability of dependable systems. Traditionally, those systems were small and
self-contained, and the main challenge for model-based evaluation has been the
efficiency of the solution process. Recently, the problem of specifying and
maintaining complex models has increasingly gained attention, as modern systems
are characterized by many components and complex interactions. Components share
similarities, but also exhibit variations in their behavior due to different
configurations or roles in the system. From the modeling perspective,
variations lead to replicating and altering a small set of base models multiple
times. Variability is taken into account only informally, by defining a sample
model and explaining its possible variations. In this paper we address the
problem of including variability in performability models, focusing on
Stochastic Activity Networks (SANs). We introduce the formal definition of
Stochastic Activity Networks Templates (SAN-T), a formalism based on SANs with
the addition of variability aspects. Differently from other approaches,
parameters can also affect the structure of the model, like the number of cases
of activities. We apply the SAN-T formalism to the modeling of the backbone
network of an environmental monitoring infrastructure. In particular, we show
how existing SAN models from the literature can be generalized using the newly
introduced formalism
Governance & Autonomy: Towards a Governance-based Analysis of Autonomy in Cyber-Physical Systems-of-Systems
Engineering Functional Safety Requirements for Automotive Systems: A Cyber-Physical-Social Approach
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