70 research outputs found

    Enabling Assurance in the MBSE Environment

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    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

    Motivations and Experiences of Female Expatriate Educators Teaching in Saudi Arabia

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    There is a significant gap in the literature regarding women\u27s lived experiences and work motivation in Saudi Arabia. In order to address this gap, this qualitative study explored the lived experiences of female expatriates who chose to teach and live in Saudi Arabia for longer than 1 year. Using Moustakas\u27 phenomenological method, a purposive sample of 10 female educators who worked in Saudi Arabian higher education institutions were recruited and interviewed. Although English teachers were not targeted, all of the participants recruited were primarily English teachers (5 North Americans, 5 Europeans). With Deci and Ryan\u27s self-determination theory as the conceptual framework, 12 themes were summarized in terms of motivation elements including autonomy, support, competence, and motivation. Themes related to teaching experiences in Saudi Arabia included job autonomy, job routines, supportive work environments, supportive supervisors, work competence, and work performance. Themes related to motivations to stay in Saudi Arabia included cultural adjustment, spiritual motivations, social connectedness, family life, unforgettable teaching moments, and women’s empowerment. The essence of teaching and living in Saudi Arabian institutions were provided. The results of this study will be used to empower female expatriate educators by increasing awareness about their experiences, offering motivation workshops, and advancing higher education accreditation policies resulting in positive social change. Future research should explore developing higher education standards related to monitoring the effects of student performance and post-Covid19 regulations on expatriate faculty motivation to live in the Middle East

    A state machine architecture for aerospace vehicle fault protection

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    Because of their complexity and the unforgiving environment in which they operate, aerospace vehicles are vulnerable to mission-critical failures. In order to prevent these failures, aerospace vehicles often employ Fault Detection, Isolation, and Recovery (FDIR) systems to sense, identify the source of, and recover from faults. Typically, aerospace systems use a rule-based paradigm for FDIR where telemetry values are monitored against specific logical statements such as static upper and lower limits. The model-based paradigm allows more complex decision logic to be used for FDIR. State machines are a particular tool for model-based FDIR that have been explored by industry but not yet widely adopted. This study develops a generic and modular state machine FDIR architecture that is portable to flight software. The study will focus on FDIR for the Guidance, Navigation, & Control subsystem, but it will be presented in a manner that is applicable to all vehicle subsystems. The state machine formulation is applied for on-board model-based fault diagnosis. Two specific case studies are employed to demonstrate the architecture. The first is a terrestrial application of unmanned aerial vehicles for 3D scanning and mapping, which is validated through flight testing. The second is a space-based application of automated close approach and capture for a Mars sample return mission, which is validated through software-in-the-loop testing with flight-like software components.Ph.D

    Armstrong Flight Research Center Research Technology and Engineering Report 2015

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    I am honored to endorse the 2015 Neil A. Armstrong Flight Research Centers Research, Technology, and Engineering Report. The talented researchers, engineers, and scientists at Armstrong are continuing a long, rich legacy of creating innovative approaches to solving some of the difficult problems and challenges facing NASA and the aerospace community.Projects at NASA Armstrong advance technologies that will improve aerodynamic efficiency, increase fuel economy, reduce emissions and aircraft noise, and enable the integration of unmanned aircraft into the national airspace. The work represented in this report highlights the Centers agility to develop technologies supporting each of NASAs core missions and, more importantly, technologies that are preparing us for the future of aviation and space exploration.We are excited about our role in NASAs mission to develop transformative aviation capabilities and open new markets for industry. One of our key strengths is the ability to rapidly move emerging techniques and technologies into flight evaluation so that we can quickly identify their strengths, shortcomings, and potential applications.This report presents a brief summary of the technology work of the Center. It also contains contact information for the associated technologists responsible for the work. Dont hesitate to contact them for more information or for collaboration ideas

    Scalable Verification of Linear Controller Software

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    We consider the problem of verifying software implementations of linear time-invariant controllers against mathematical specifications. Given a controller specification, multiple correct implementations may exist, each of which uses a different representation of controller state (e.g., due to optimizations in a third-party code generator). To accommodate this variation, we first extract a controller\u27s mathematical model from the implementation via symbolic execution, and then check input-output equivalence between the extracted model and the specification by similarity checking. We show how to automatically verify the correctness of C code controller implementation using the combination of techniques such as symbolic execution, satisfiability solving and convex optimization. Through evaluation using randomly generated controller specifications of realistic size, we demonstrate that the scalability of this approach has significantly improved compared to our own earlier work based on the invariant checking method

    LADEE Flight Software: Verification Techniques

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    Organisational transparency in South African banking : an institutional field discourse analysis

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    Abstract in English with Zulu and SeTswana translationsThis thesis examines organisational transparency in South African banking after the financial crisis of 2007-2009. The crisis upset the global economy and resulted in general mistrust in banks and the global financial system. In addition to poor governance standards, inadequate transparency was identified as a key issue to be addressed in order to prevent future crises. The nature and consequences of banking transparency became a matter of worldwide debate. While the extant literature focuses mainly on banking transparency in the context of accounting, this study uses a communication perspective, examining transparency as a dynamic social and organisational phenomenon that is constituted through and reflected in organisational discourse, with both symbolic and practical implications. The primary objective of this study was to establish how the discourse in the institutional field of banking in South Africa after the Financial Crisis shaped the construction of the meaning of transparency in banking, and consequently how organisational field level discourse contributed to the institutionalisation of transparency practices in South African banking. The study adapted several conceptual frameworks previously used in discourse studies in order to analyse a banking field discourse at meso-level. From the data analysis perspective, the qualitative content analysis was performed with the aid of ATLAS.ti 8 software. The sample for the study comprises 76 purposively selected documents produced by the actors within the institution field of banking from the onset of the Financial Crisis until 2018. This study underlines the importance of the discourse within the institutional field of banking in South Africa and the construction of what is normal, acceptable and expected in terms of banking transparency, and its institutionalisation, thus highlighting the historical and social embeddedness of banking transparency. The data analysis identifies the main discursive strands within the banking discourse: one that is focused on market conduct transparency and the other, which addresses the importance of banks’ transparency in maintaining stability in the financial system. The results also reveal multiple meanings of transparency in South African banking and draw attention to the historical and discursive events that trigger change in institutional fields.Le thesisi iphenya ukusebenza shashalazi kwenhlangano eNingizimu Afrika ngemuva kwenhlekelele yezimali ukusukela ngo 2007 ukufika ngo 2009. Le nhlekelele yaguqula isimo somhlaba kwezomnotho yaze yadala izinga lokungasathembeki kwamabhangi nohlelo lwezimali emhlabeni wonke. Ukwengeza phezu kwamazinga angagculisi okuphathwa kwamabhizinisi, ukungasebenzi shashalazi ngokwanele kuye kwabonwa njengodaba oluyinkinga okufanele luxazululwe ukugwema izinkinga esikhathini esizayo. Ubunjalo besimo kanye nemiphumela yohlelo olushashalazi lwemboni yezamabhangi kugcine sekuba wudaba oluxoxwa umhlaba wonke. Njengoba umbhalo wobuciko okhona ugxile kakhulu phezu kohlelo olushashalazi lwamabhangi kweze-accounting, lolu cwaningo lusebenzisa umqondo wezokuxhumana, luhlola uhlelo olushashalazi njengohlelo lwenhlangano yomphakathi oluguqukayo futhi olwakhekayo, kanti lolu hlelo lubonakala njengodaba lwenhlangano, ngendlela yophawu nangendlela ephathekayo. Inhloso yokuqala yalolu cwaningo kwabe kukuthola indlela lesi sifundo emkhakheni weziko lezamabhangi eNingizimu Afrika ngemuva kokuthi iziNhlekelele zeZimali zishintshe isakhiwo sencazelo yegama lokusebenza shashalazi kwezamabhangi, bese ekugcineni ingabe udaba lwezinga lomkhakha wenhlangano lube negalelo elinjani ekwakhiweni kwezingqubo zohlelo olushashalazi embonini yezamabhangi eNingizimu Afrika. Ucwaningo luguqule izakhiwo zegama ezimbalwa ebezisetshenziswa esikhathini esedlule ezifundweni zocwaningo ukuhlaziya udaba lomkhakha wezamabhangi ezingeni lomhlaba. Ngokomqondo wokuhlaziywa kwedatha, ukuhlaziywa ngendlela egxile kwingxoxo yolwazi olumumethwe kwenziwa ngosizo lwe-ATLAS.ti 8 software. Isampula yocwaningo iqukethe imibhalo engama-76 ekhethwe ngenhloso ekhiqizwe ngabadlali abangaphakathi komkhakha weziko lezamabhangi ngesikhathi sokuqala kweNhlekelele yeZezimali ukufika ngonyaka ka 2018. Ucwaningo lugcizelela ukubaluleka kwesifundo esingaphakathi komkhakha weziko lezamabhangi kanye nokwakhiwa kwalokho okuthathwa ukuthi kujwayelekile, kuyamukeleka futhi kulindelwe mayelana nohlelo lokusebenza shashalazi kwamabhangi, kanye nokkwakhiwa kwalolu hlelo, ngakho-ke lokhu kuveza umlando kanye kanye nabantu ohlelweni lokusebenza shashalazi kwezamabhangi. Ukuhlaziywa kwedatha kwenze ukuthi kuphawuleke izimpawu ezibalulekile ezidukisayo ngaphakathi kohlelo lwezamabhangi; olunye lugxile phezu kohlelo olushashalazi mayelana nokuziphatha kwamabhangi, kanti olunye lubhekene nokubaluleka kohlelo olushashalazi kwezamabhangi ngenhloso yokugcina ingqubo ezinzile ohlelweni lwezezimali. Imiphumela nayo iveza izincazelo eziningi zohlelo lokusebenza shashalazi kwamabhangi eNingizimu Afrika kanye nokuxwayisa ngomlando nangezehlakalo ezidukisayo eziphembelela ukuthi kube nezinguquko emikhakheni yamaziko.Phuputso ena e hlahloba ponaletso ya mokgatlo lekaleng la dibanka tsa Afrika Borwa kamora koduwa ya ditjhelete ya ho tloha 2007 ho isa ho 2009. Koduwa ena e ile ya ferekanya moruo wa lefatshe mme ya fella ka ho se tsheptjwe ha dibanka le tsamaiso ya ditjhelete ya lefatshe. Ntle le maemo a mabe a puso, ponaletso e sa lekanang e ile ya hlwauwa e le taba ya mantlha e lokelang ho rarollwa ho thibela mathata a kamoso. Sebopeho le ditlamorao tsa ponaletso ya dibanka ebile taba ya puisano ya lefatshe ka bophara. Leha dingodilweng tse fumanehang hona jwale di shebile ponaletso ya dibanka haholo-holo maemong a ho boloka dibuka, phuputso ena e sebedisa pono ya puisano, e lekolang ponaletso e le taba e matla ya phedisano le mokgatlo e hlophisitsweng ka, mme e bontshitswe puong ya mokgatlo, ka diphello tsa matshwao le tse sebetsang ka bobedi. Morero wa mantlha wa phuputso ena e ne e le ho tiisa hore na puo lefapheng la dibanka Afrika Borwa kamora Koduwa ya Ditjhelete e thehile kaho ya moelelo wa ponaletso dibankeng jwang, le hore na puo ya boemo ba mokgatlo e kentse letsoho jwang ho hlophiseng mekgwa ya ponaletso dibankeng tsa Afrika Borwa. Phuputso e ile ya hlophisa meralo e mmalwa e neng e sebedisitswe diphuputsong tse fetileng tsa dipuo e le ho manolla puo ya lekala la dibanka maemong a bohareng. Ho latela pono ya manollo ya lesedi, manollo ya boleng ba dikateng e entswe ka thuso ya software ya ATLAS.ti 8. Sampole ya phuputso e na le ditokomane tse kgethilweng ka boomo tse 76 tse hlahisitsweng ke ba amehang lefapheng la dibanka ho tloha qalong ya Koduwa ya Ditjhelete ho fihlela 2018. Phuputso ena e totobatsa bohlokwa ba puo kahare ho lefapha la dibanka Afrika Borwa le kaho ya se tlwaelehileng, se amohelehang le se lebelletsweng mabapi le ponaletso ya dibanka, le tlhophiso ya yona ka hona ho totobatsa ho kenella ha nalane le phedisano ho ponaletso ya dibanka. Manollo ya lesedi e hlwaya dikarolwana tse ka sehloohong tse ka hare ho puo ya banka: e nngwe e shebane le ponaletso ya boitshwaro ba mmaraka, ha e nngwe e bua ka bohlokwa ba ponaletso ya dibanka ho boloka botsitso tsamaisong ya ditjhelete. Diphetho di boetse di senola ditlhaloso tse ngata tsa ponaletso dibankeng tsa Afrika Borwa le ho lebisa tlhokomelo diketsahalong tsa nalane le tse amanang le puo tse bakang phetoho makaleng a ditsi.Communication ScienceD. Phil. (Communication

    Building and Using a Small Macroeconometric Model: Klein Model I as an Example

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    This book describes the estimation and use of Klein Model I, including the formation of the individual equations, the data used for its estimation and the methodology of the construction and use of the model involving the MODLER software and an electronic compute

    EVIDENCE FOR TRUSTED DIGITAL REPOSITORY REVIEWS: AN ANALYSIS OF PERSPECTIVES

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    Jonathan David Crabtree: Evidence for Trusted Digital Repository Reviews: An Analysis of Perspectives(Under the direction of Dr. Helen R. Tibbo) Building trust in our research infrastructure is important for the future of the academy. Trust in research data repositories is critical as they provide the evidence for past discoveries as well as the input for future discoveries. Archives and repositories are examining their options for trustworthy review, audit, and certification as a means to build trust within their content creator and user communities. One option these institutions have is to increase and demonstrate their trustworthiness is to apply for the CoreTrustSeal. Applicants for the CoreTrustSeal are becoming more numerous and diverse, ranging general purpose repositories, preservation infrastructure providers, and domain repositories. This demand for certification and the subjective nature of decisions around levels of CORETrustSeal compliance drives this dissertation. It is a study of the review process and its veracity and consistency in determining the trustworthiness of applicant repositories. Several assumptions underlie this work. First, audits and reviews must be based on evidence supplied by the repository under scrutiny; second, and not all reviewers will approach a piece of evidence in the same fashion or give it the same weight. Third, the value and veracity of required evidence may be subject to reviewers’ diverse perspectives and diverse repository community norms. This research used a thematic qualitative analysis approach to identify similarities and differences in CoreTrustSeal reviewers’ responses during semi-structured interviews in order to better understand potential subjective differences among respondents. The participants’ non-probabilistic sample represented a balance in perspectives across three anticipated categories: administrator, archivist, and technologist. Themes converged around several key concepts. Nearly all participants felt they were performing a peer review process and working to help the repository community and the research enterprise. Reviewers were questioned about the various CoreTrustSeal application requirements and which ones they felt were the most important. No clear evidence emerged to indicate that variations in perspectives affected the subjective review of application evidence. The same categories of evidence were often selected and identified as being critical across all three categories (i.e., administrator, archivist, and technologist). Many valuable suggestions from participants were recorded and can be implemented to ensure the consistency and sustainability of this trusted repository review process. These suggestions and concepts were also very evenly distributed across the three perspectives. The balance in perspectives is potentially due to participants’ experience levels and their years of experience in various positions, holding many responsibilities, within the organizations they represented.Doctor of Philosoph
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