A Model-Based System Engineering Approach to Support System Architecting Activities in Early Aircraft Design

The aviation industry aims to reduce its environmental footprint and meet ambitious environmental targets, prompting the exploration of novel aircraft concepts and systems, such as hybrid-electric or distributed propulsion. These emerging technologies introduce complexity to aircraft system architectures, requiring innovative approaches to design, optimization, and safety assessment, particularly for system architecting. Several aspects of system architecting specification and evaluation are typically performed separately, using different people and a mix of manual and model-based processes. Connecting these activities has the potential to make the design process more efficient and effective. This thesis explores how a Model-Based Systems Engineering (MBSE) specification environment can be structured and enriched to enable a better bridge to Multidisciplinary Design Analysis and Optimization (MDAO) and Model-Based Safety Assessment (MBSA) activities. The proposed MBSE approach focuses on enhancing system specifications, particularly for unconventional system architectures, which typically feature greater variability in early design stages. Using the ARCADIA/Capella MBSE environment, a multi-level approach is proposed to structure the system architecture specification and the Property Value Management Tool (PVMT) add-on is used to facilitate the bridge to other system architecting activities. In addition, a catalogue of modeling artifacts is established to facilitate the development of various hybrid-electric system configurations. The MDAO link mechanism is demonstrated with an example from the collaborative AGILE4.0 project. Two test cases demonstrate the implementation of the approach: a hybrid-electric propulsion system and associated sub-systems for the overall approach and the landing gear braking system for the model-based Functional Hazard Analysis (FHA), as an example of an MBSA activity. Overall, this thesis helps improve the integration and collaboration between engineers working on MBSE, MDAO, and MBSA. This better integration will help to reduce the development time and risk. Therefore, the presented thesis contributes to a more efficient aircraft development process, enabling the industry to tackle the emerging needs of unconventional aircraft systems and their integration

Proposed extension of specification approach to meet needs of RCA

This document is deliverable D10.2, describing extensions of the MBSE specification approach to needs of future Functional Railway System Architectures within Task 10.3 of work package WP10 Formal Methods for Functional Railway System Architecture, within the X2Rail-5 project. This deliverable is concerned with a specification approach meeting the needs in ongoing and future developments of ERTMS, and the European initiatives RCA and EULYNX. This is a rather large scope, whose general high-level goal may be formulated as: Determine a suitable approach to specify, verify, and validate system requirements, that can meet the needs of initiatives and projects RCA and EULYNX that define a future system architecture

Design techniques to support aircraft systems development in a collaborative MDO environment

The aircraft design is a complex multidisciplinary and collaborative process. Thousands of disciplinary experts with different design competences are involved within the whole development process. The design disciplines are often in contrast with each other, as their objectives might be not coincident, entailing compromises for the determination of the global optimal solution. Therefore, Multidisciplinary Design and Optimization (MDO) algorithms are being developed to mathematically overcome the divergences among the design disciplines. However, a MDO formulation might identify an optimal solution, but it could be not sufficient to ensure the success of a project. The success of a new project depends on two factors. The first one is relative to the aeronautical product, which has to be compliant with all the capabilities actually demanded by the stakeholders. Furthermore, a “better” airplane may be developed in accordance with customer expectations concerning better performance, lower operating costs and fewer emissions. The second important factor refers to the competitiveness among the new designed product and all the other competitors. The Time-To-Market should be reduced to introduce in the market an innovative product earlier than the other aeronautical industries. Furthermore, development costs should be decreased to maximize profits or to sell the product at a lower price. Finally, the development process must reduce all the risks due to wrong design choices. These two main motivations entail two main objectives of the current dissertation. The first main objective regards the assessment and development of design techniques for the integration of the aircraft subsystems conceptual design discipline within a collaborative and multidisciplinary development methodology. This methodology shall meet all the necessities required to design an optimal and competitive product. The second goal is relative to the employment of the proposed design methodology for the initial development of innovative solutions. As the design process is multidisciplinary, this thesis is focused on the on-board systems discipline, without neglecting the interactions among this discipline with all the other design disciplines. Thus, two kinds of subsystems are treated in the current dissertation. The former deals with hybrid-electric propulsion systems installed aboard Remotely Piloted Aerial Systems (RPASs) and general aviation airplanes. The second case study is centered on More and All Electric on-board system architectures, which are characterized by the removal of the hydraulic and/or pneumatic power generation systems in favor of an enhancement of the electrical system. The proposed design methodology is based on a Systems Engineering approach, according to which all the customer needs and required system functionalities are defined since the earliest phase of the design. The methodology is a five-step process in which several techniques are implemented for the development of a successful product. In Step 1, the design case and the requirements are defined. A Model Based Systems Engineering (MBSE) approach is adopted for the derivation and development of all the functionalities effectively required by all the involved stakeholders. All the design disciplines required in the MDO problem are then collected in Step 2. In particular, all the relations among these disciplines – in terms of inputs/outputs – are outlined, in order to facilitate their connection and the setup of the design workflow. As the present thesis is mainly focused on the on-board system design discipline, several algorithms for the preliminary sizing of conventional and innovative subsystems (included the hybrid propulsion system) are presented. In the third step, an MDO problem is outlined, determining objectives, constraints and design variables. Some design problems are analyzed in the present thesis: un-converged and converged Multidisciplinary Design Analysis (MDA), Design Of Experiments (DOE), optimization. In this regard, a new multi-objective optimization method based on the Fuzzy Logic has been developed during the doctoral research. This proposed process would define the “best” aircraft solution negotiating and relaxing some constraints and requirements characterized by a little worth from the user perspective. In Step 4, the formulation of the MDO problem is then transposed into a MDO framework. Two kinds of design frameworks are here considered. The first one is centered on the subsystems design, with the aim of preliminarily highlighting the impacts of this discipline on the entire Overall Aircraft Design (OAD) process and vice-versa. The second framework is distributed, as many disciplinary experts are involved within the design process. In this case, the level of fidelity of the several disciplinary modules is higher than the first framework, but the effort needed to setup the entire workflow is much higher. The proposed methodology ends with the investigation of the design space through the implemented framework, eventually selecting the solution of the design problem (Step 5). The capability of the proposed methodology and design techniques is demonstrated by means of four application cases. The first case study refers to the initial definition of the physical architecture of a hybrid propulsion system based on a set of needs and capabilities demanded by the customer. The second application study is focused on the preliminary sizing of a hybrid-electric propulsion system to be installed on a retrofit version of a well-known general aviation aircraft. In the third case study, the two kinds of MDO framework previously introduced are employed to design conventional, More Electric and All Electric subsystem architectures for a 90-passenger regional jet. The last case study aims at minimizing the aircraft development costs. A Design-To-Cost approach is adopted for the design of a hybrid propulsion system

A Quantitative Research Study on Probability Risk Assessments in Critical Infrastructure and Homeland Security

This dissertation encompassed quantitative research on probabilistic risk assessment (PRA) elements in homeland security and the impact on critical infrastructure and key resources. There are 16 crucial infrastructure sectors in homeland security that represent assets, system networks, virtual and physical environments, roads and bridges, transportation, and air travel. The design included the Bayes theorem, a process used in PRAs when determining potential or probable events, causes, outcomes, and risks. The goal is to mitigate the effects of domestic terrorism and natural and man-made disasters, respond to events related to critical infrastructure that can impact the United States, and help protect and secure natural gas pipelines and electrical grid systems. This study provides data from current risk assessment trends in PRAs that can be applied and designed in elements of homeland security and the criminal justice system to help protect critical infrastructures. The dissertation will highlight the aspects of the U.S. Department of Homeland Security National Infrastructure Protection Plan (NIPP). In addition, this framework was employed to examine the criminal justice triangle, explore crime problems and emergency preparedness solutions to protect critical infrastructures, and analyze data relevant to risk assessment procedures for each critical infrastructure identified. Finally, the study addressed the drivers and gaps in research related to protecting and securing natural gas pipelines and electrical grid systems

Metagenomic Applications in Virus Discovery, Ecology, and the Surveillance of Australian Wildlife

Metagenomic next-generation sequencing (mNGS), particularly total RNA sequencing (“meta-transcriptomics”), has led to a revolution in virus discovery, veterinary diagnostics and virus evolution. Wildlife naturally harbour a diverse assemblage of infectious microorganisms and these can be a source of novel, and often poorly studied, diseases of humans and other animals. Many mortality and morbidity events in wildlife are long-standing, neglected and unsolved. These include wobbly possum disease, black and white bird disease, clenched claw syndrome and bearded dragon respiratory disease. To provide a new understanding of these diseases and identify pathogens in diseased wildlife with unknown aetiology across different taxa, I developed and applied a meta-transcriptomic-based pipeline that was used in combination with retrospective clinical metadata, histopathology, phylogeny, and molecular assays. Accordingly, novel viruses were identified from a wide range of virus families, including the Circoviridae, Chaphamaparvoviridae, Flaviviridae, Astroviridae, Picornaviridae, Paramixoviridae, Adenoviridae, and Polyomaviridae, greatly extending our knowledge of virus diversity in wildlife, including marsupials, birds, and reptiles from both the wild and captive environments. Similarly, through exploiting meta-transcriptomic approaches and mining the Sequence Read Archive, I discovered four novel hepatitis delta-like viruses from fish, amphibians and termites, thereby rejecting the concept that hepatitis delta viruses are only associated with humans. In sum, my work highlights a successful combination of metagenomics with traditional tools to transform veterinary clinical diagnostics and disease surveillance. In doing so, it sheds light on the enormous diversity of viruses, elucidating their origins and evolutionary history, and allowing the discovery of pathogens from wildlife biodiversity diseases within a One Health perspective

I am not your Student-Athlete: An Investigation of Social Identity Complexity as a Stereotype Threat Mitigation Strategy and Individual Differences that may moderate the effect

Collegiate athletes must contend with negative stereotypes during their academic career (Comeaux, 2012). Such stereotypes depict student-athletes as unintelligent (Yopyk & Prentice, 2005) and overlook the benefits and variability of the collegiate athletic experience. Student-athletes are multifaceted and more than their sport. Unfair depictions can influence student-athletes’ behavior, especially in the classroom. Research shows that student-athletes’ academic performance is affected by stereotype threat (Riciputi & Erdal, 2017); which is the apprehension of confirming a negative stereotype about one’s social group (Steele & Aronson, 1995). Currently, there is no published evidence-based research on stereotype threat mitigation strategies tailored to student-athletes. Expanding the work of Gresky et al. (2005), this study explored a self-concept map activity, based on the social identity complexity theory, as one potential strategy for collegiate athletes (exploring multiple social identities). Division I student-athletes (N = 70) were randomly assigned to one of three experimental conditions: 1) threat-no mitigation, 2) threat-mitigation, and 3) no threat-no mitigation (control). Factorial ANOVA was employed to assess differences in participants’ scores on an SAT-style examination (writing/language and mathematics) across conditions. Academic self-concept, gender identity, and race/ethnicity served as grouping variables and potential moderators. Results showed no significant differences in overall test performance across experimental conditions, or between gender identity (female and male). Results revealed several main effects of academic self-concept and race/ethnicity on components of performance, especially on difficult test items. Specific to the main hypothesis, a marginally significant (p = .052) interaction effect of condition by race/ethnicity was observed on the difficult math items. Post-hoc analyses showed that African American student-athletes had significantly poorer scores in the control condition than Caucasian student-athletes (p = .010), and in the threat condition than did Caucasian (p = .001) and Hispanic (p = .004) student-athletes. There was no difference between these groups in the mitigation condition. African American participants’ performance on difficult math items in the mitigation condition was significantly better than their performance in the threat condition (p = .02). These results suggest that stereotype threat mitigations may work, but strategies should be culturally-specific and tailored to the challenge of the academic tasks

University of San Diego News Print Media Coverage 2007.02

Printed clippings housed in folders with a table of contents arranged by topic.https://digital.sandiego.edu/print-media/1049/thumbnail.jp