IDC Seminar by Assistant Professor Rhea P. Liem

27 Nov 2015 12.00 pm to 1.00 pm Lecture Theatre 5, Building 2 Level 5, 2.505

You are cordially invited to a seminar by Assistant Professor Rhea P. Liem.
Aerodynamic  shape and aerostructural  design optimizations that maximize the performance at a single flight condition result in designs with unacceptable off-design performance.  While considering multiple flight conditions in the optimization improves the robustness of the designs, there is a need to develop a rational strategy for choosing the flight conditions and their relative emphases such that multipoint optimizations reflect the true objective function. In addition, there is a need to consider uncertain missions and flight conditions.
In this talk, the strategies to formulate the multipoint objective functions for aerodynamic shape and aerostructural optimization are presented. To determine the flight conditions and their corresponding weights, a novel surrogate-based mission analysis was developed and used to efficiently analyze hundreds of actual mission data, to emulate their flight condition distribution. Using accurate and reliable surrogate models to approximate the aerodynamic coefficients used in the analysis makes this procedure computationally tractable, Professor Rhea developed a mixture of experts (ME) approach to overcome the limitations of conventional surrogate models in modeling the complex transonic drag profile.
The ME approach combines multiple surrogate models probabilistically based on the divide-and-conquer strategy. In this talk, Professor Rhea will briefly describe this ME approach and show that using this model can significantly improve the range estimation accuracy in the mission analysis, as compared  to using other conventional surrogate models. She will then talk about how to use the generated flight-condition distribution in the multipoint objective function formulations. The optimization results clearly demonstrate the merits of performing multipoint optimizations, as opposed to single-point optimizations. Moreover, by using historical flight data to derive the objective function, we ensure that the optimization problem formulation matches with real-world operations.
About the Speaker
Assistant Professor Rhea P. Liem obtained her Bachelor of Engineering degree from the School of Mechanical and Production Engineering, Nanyang Technological University. Her undergraduate study was supported by the Association of Southeast Asian Nations (ASEAN) with a 4-year merit-based full scholarship. She earned Master of Science (S.M.) degrees in Computation for Design and Optimization (supported by the Singapore-MIT Alliance Fellowship Award), and Aeronautics/Astronautics, from the Massachusetts Institute of Technology (MIT). She then pursued her PhD degree in the Multidisciplinary Design Optimization (MDO) Laboratory, University of Toronto Institute for Aerospace Studies (UTIAS), as a Vanier Canada Graduate Scholar. She is also a 2012 Amelia Earhart Fellow.  Professor Liem's main research interest is in aerospace computation, in particular surrogate modeling and optimization with applications in the context of aircraft design.