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Kotsifakis, David

Publications and source records attributed to Kotsifakis, David.

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2020

NASA Quality Assurance in an MBSE world

Over the past decade or so, the emergence of Model Based Systems Engineering (MBSE) has demonstrated its desirability and value in terms of 1) being a single source of truth, 2) unambiguous definitions and relationships, and 3) after representation, the ability to explore/extract any sets of data on demand. While much work has been done in showing the value to the system engineering discipline in these areas, how does that value translate to the Safety and Mission Assurance (S&MA) world? This paper provides a vision of a very desirable future of NASA S&MA after it is fully integrated into the MBSE framework. We explore the impact and consequences of the MBSE Value items discussed above and how they impact the disciplines of quality assurance, reliability and maintainability, system safety, and software assurance. We provide insight into how the MBSE modeling tools can be used to define S&MA processes (ideally as a result of Use Case [1] elaboration of processes represented in MagicDraw®), produce S&MA products (ViewEditor output of various items), and represent S&MA disciplines (S&MA inside of MagicDraw). We also provide insight into the degree to which some elements can be directly integrated into a SysML® model and when, as often happens, an interface to some external source must be provided. The desirability of this future is part of the reason for the NASA Office of Safety and Mission Assurance’s (OSMA) recent creation of a Model Based Mission Assurance (MBMA) Program [2] and the MBMA annual workshops. We briefly summarize the efforts to date to generate S&MA Use Cases for eventual deployment into pilot and project efforts. Even simple use of the SysML modeling tools can be used to capture quality assurance tasks and integrate them with the systems engineering and produce products that are easy to use by quality practitioners that are unfamiliar with these methods. We anticipate finding opportunities to pilot and implement various Quality Assurance (QA) Use Cases in FY20. The MBMA Program is focused on implementation; the NASA Office of the Chief Engineer's Community of Practice, as well as the SmallSat communities, are very interested in the integration of S&MA. Finally, as projects move forward utilizing whatever efficiency increases they can find in a cost-constrained environment, the S&MA community cannot be caught unawares and needs to continue preparing for the ever-growing implementation of MBSE across NASA and our government and commercial partners.

Evans, John W↗
NASA NTRS2020

NASA quality assurance in an MBSE world

We explore the impact and consequences of the MBSE Value items discussed above and how they impact the disciplines of quality assurance, reliability and maintainability, system safety, and software assurance. We provide insight into how the MBSE modeling tools can be used to define S&MA processes (ideally as a result of Use Case [1] elaboration of processes represented in MagicDraw®), produce S&MA products (ViewEditor output of various items), and represent S&MA disciplines (S&MA inside of MagicDraw). We also provide insight into the degree to which some elements can be directly integrated into a SysML® model and when, as often happens, an interface to some external source must be provided.

Evans, John W.↗
NASA NTRS2020

Enabling Assurance in the MBSE Environment

A number of specific benefits that fit within the hallmarks of effective development are realized with implementation of model-based approaches to systems and assurance. Model Based Systems Engineering (MBSE) enabled by standardized modeling languages (e.g., SysML®) is at the core. These benefits in the context of spaceflight system challenges can include [1]: • Improved management of complex development • Reduced risk in the development process • Improved cost management • Improved design decisions With appropriate modeling techniques the assurance community also can improve early oversight and insight into project development. NASA has shown the basic constructs of SysML in an MBSE environment offer several key advantages, within a Model Based Mission Assurance (MBMA) initiative [2, 3]. These include the following: • Model viewpoints that promote rapid and systematic assessment of requirements coverage, hazard tagging and risk management • Embedded safety assessments for launch vehicles • Deployment of model assisted development of reliability products - Failure Modes and Effects Analyses (FMEAs) and Fault Trees • Test Planning • Validation and Verification of complex functions • Support of Assurance Case development for complex systems In addition, while there are benefits to be harvested, there is a realization that these do not come without effort and cost. Enabling model-based approaches requires structure, not only in an organizational context, but in a modeling context as well. There can be a steep learning curve and costs associated to train skilled modelers. But, on the other hand, not all of the assurance community need to be modelers. Models themselves must conform to ontologies that enable assurance. This places constraints upon the models and modelers. Optimums have yet to be developed where resources and constraints on modeling must be traded off in the organization and modeling efforts for projects. A number of barriers need to be overcome, as well, which pose challenges to the developers of the software that supports MBSE/MBMA. Information and data must be made to flow seamlessly through the life cycle. Because there is a wide variety of tools used in the community, to avoid the problems of the past of silos, delays, and diverging interests, information should flow among these tools to support the “single source of truth” paradigm of MBSE. This will greatly facilitate MBMA and advancement of assurance functions.

Evans, John W.↗
NASA NTRS2019

Enabling Assurance in the MBSE Environment

A number of specific benefits that fit within the hallmarks of effective development are realized with implementation of model-based approaches to systems and assurance. Model Based Systems Engineering (MBSE) enabled by standardized modeling languages (e.g., SysML®) is at the core. These benefits in the context of spaceflight system challenges can include: Improved management of complex development, Reduced risk in the development process, Improved cost management, Improved design decisions. With appropriate modeling techniques the assurance community can improve early oversight and insight into project development. NASA has shown the basic constructs of SysML in an MBSE environment offer several key advantages, within a Model Based Mission Assurance (MBMA) initiative.

Evans, John W.↗