Browsing by Author "Jimeno, Sergio"

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    Enabling interactive safety and performance trade-offs in early airframe systems design
    (AIAA, 2020-01-05) Jimeno, Sergio; Riaz, Atif; Guenov, Marin D.; Molina-Cristobal, Arturo
    Presented is a novel interactive framework for incorporating both safety and performance analyses in early systems architecture design, thus allowing the study of possible trade-offs. Traditionally, a systems architecture is first defined by the architects and then passed to experts, who manually create artefacts such as Fault Tree Analysis (FTA) for safety assessment, or computational workflows, for performance assessment. The downside of this manual approach is that if the architect modifies the systems architecture, most of the process needs to be repeated, which is tedious and time consuming. This limits the exploration of the design space, with the associated risk of missing better architectures. To overcome this limitation, the proposed framework automates parts of the safety and performance analysis in the context of the Requirement, Functional, Logical, and Physical (RFLP) systems engineering paradigm. Safety analysis is carried out by automatic creation of FTA models from the functional and logical flow views. Regarding performance analysis, computational workflows are first automatically created from the logical flow view, and then executed for a set of flight conditions over the range of the mission in order to determine the most demanding condition. Finally, performance characteristics of the subsystems, such as weights, power offtakes, ram drag etc. are evaluated at the most demanding flight condition, which enables the architect to compare architectures at aircraft level. The framework is illustrated with a representative example involving the design of an environmental control system of a civil aircraft, where the safety and performance trade-off is conducted for multiple ECS architectures.
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    Incorporating safety in early (airframe) systems design and assessment
    (AIAA, 2019-01-14) Jimeno, Sergio; Molina-Cristobal, Arturo; Riaz, Atif; Guenov, Marin D.
    Presented is a novel framework for incorporating safety analysis in early systems architecture design.Traditionally, a systems architecture is first defined by the architects and then passed to safety experts, who manually create artefacts such as Function Hazard Analysis (FHA) or Fault Tree Analysis (FTA) for safety assessment. The problem with this manual approach is that if the architect modifies the systems architecture, then the whole safety assessment process needs to be repeated, which is tedious and time consuming. To overcome this limitation, the proposed framework automates the creation of safety models such as FHA and FTA by utilizing the Requirement, Functional, Logical, and Physical (RFLP) systems engineering paradigm. The framework supports three main activities. First, the safety targets are determined by performing a FHA of the architecture and the Requirements view is updated. Second, compliance with the safety requirements is analyzed using dynamic fault trees, automatically generated from the Logical view. Interactive visualization techniques are proposed to interpret the safety results, e.g. highlighting the greatest contributors to the probability of failure. Third, an algorithm is developed that enables the designer to interactively improve the architecture’s safety by introducing more reliable components or increasing redundancy. The concept is illustrated with a representative example, where the environmental control system of a civil aircraft is studied from a safety point of view.