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Georgia Tech

1. Dykes, John William. TEMPUS: A methodology for model-based robust-optimal design of time-dynamic system identification experiments using variational asymptotic expansions.

Degree: PhD, Aerospace Engineering, 2016, Georgia Tech

The development of appropriate flight tests has proven to be a critical element in the development process of many revolutionary next-generation aerospace vehicles. For example, in the case of hypersonic vehicles with air-breathing SCRAMjet engines, sophisticated computational analyses have been developed which require extensive validation and calibration with physical test data. The current state of hypersonic ground testing facilities has not yet been able to accommodate these demands due to the inability to replicate hypersonic flow conditions with sufficient accuracy. These deficiencies have put increased demand and pressure on hypersonic flight testing experiments which have historically proven to produce the highest quality results but at the potential price of extreme complexity and expense. In the case of hypersonic flight testing for SCRAMjet vehicles, the combination of high expense, high complexity, and high modeling uncertainties has led to conservative, risk-averse experiments. These efforts have historically yielded little gain in knowledge, observing only marginal improvements to prediction confidence in the computational models. There is an entire discipline devoted to the process of design and information extraction from aerospace-type experiments known as aircraft system identification (SysID) which combines three interdependent topics: (i) computational modeling and simulation, (ii) experimental design methods, and (iii) statistical estimation techniques. Essentially, SysID attempts to develop time-dynamic experiments so that statistical estimation techniques can most effectively be used to identify high-confidence physics-based models. An implicit limitation to this process lies within the topic of dynamic experiment design, often posed as a mixed parameter optimization/optimal control problem for the concurrent design of aircraft maneuver inputs, instrumentation system parameters, flight conditions, test duration, etc. Here, Fisher information-based optimality criterion are sought to be used for the quantification of information quality; however, these metrics can only be accurately computed if the true values of the unknown model parameters (e.g. SCRAMjet aero-propulsive-elastic stability and control coefficients, vehicle mass/inertia parameters, etc.) are known prior to conducting an actual experiment, which is often not the case. This is commonly referred to as the circulatory problem in statistics literature, suggesting that dynamic optimal experiment design (DOED) requires an augmented robust-optimization approach (DROED) to account for modeling uncertainties. This research focuses on the design of flight-dynamic experiments from the perspective of an integrated system for the concurrent design of information-dense flight experiments which are robust with respect to model parameter uncertainties. The proposed methodology is called TEMPUS, which stands for Time-dynamic Experiment design using a Model-based approach to Propagate Uncertainty for System identification. By using the top-down… Advisors/Committee Members: Mavris, Dimitri N. (advisor), de la Llave, Rafael (committee member), Zumberge, Jon (committee member), Domercant, Charles (committee member), Schrage, Daniel (committee member), Sankar, Lakshmi (committee member).

Subjects/Keywords: Variational asymptotic expansions; System identification; Information experiments; Robust-optimal dynamic experiment design; Model-based; Hypersonic flight testing; SCRAMjet; Generic hypersonic vehicle model

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Dykes, J. W. (2016). TEMPUS: A methodology for model-based robust-optimal design of time-dynamic system identification experiments using variational asymptotic expansions. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/59120

Chicago Manual of Style (16th Edition):

Dykes, John William. “TEMPUS: A methodology for model-based robust-optimal design of time-dynamic system identification experiments using variational asymptotic expansions.” 2016. Doctoral Dissertation, Georgia Tech. Accessed October 15, 2019. http://hdl.handle.net/1853/59120.

MLA Handbook (7th Edition):

Dykes, John William. “TEMPUS: A methodology for model-based robust-optimal design of time-dynamic system identification experiments using variational asymptotic expansions.” 2016. Web. 15 Oct 2019.

Vancouver:

Dykes JW. TEMPUS: A methodology for model-based robust-optimal design of time-dynamic system identification experiments using variational asymptotic expansions. [Internet] [Doctoral dissertation]. Georgia Tech; 2016. [cited 2019 Oct 15]. Available from: http://hdl.handle.net/1853/59120.

Council of Science Editors:

Dykes JW. TEMPUS: A methodology for model-based robust-optimal design of time-dynamic system identification experiments using variational asymptotic expansions. [Doctoral Dissertation]. Georgia Tech; 2016. Available from: http://hdl.handle.net/1853/59120

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