“Wing Performance at the Scale of Birds”
Presented by Professor Geoffrey Spedding, Aerospace and Mechanical Engineering, University of Southern California
Aeronautics is a mature and powerful discipline, and great success has been achieved in predicting flows and designing aircraft configurations at quite large scales, where the effects of viscosity can be modeled as minor modifications to basically inviscid dynamics. That is not the case at smaller scales, those of the new generation of drones, and of smaller birds and bats. Here the competing inertial and viscous terms lead to a delicate balance in solutions that have extreme sensitivity to variations in boundary and initial conditions. In this talk we will show how, in a Reynolds number regime that is only now becoming of practical interest, nominally simple problems do not necessarily have simple solutions, and how seemingly modest computational and experimental goals remain elusive.
Geoffrey Spedding received his Ph.D. in 1981 from the University of Bristol, England. He began work as a Research Associate in the Department of Aerospace Engineering at the University of Southern California in the same year, where he worked on models of insect wings and models of atmospheres and oceans. He became a full Professor in 2005, and Chair of the Aerospace and Mechanical Engineering Department in 2010. His current research has three themes: (i) Geophysical Fluids: particularly the evolution of turbulence in oceans and atmospheres, and its relation to the persistence of wakes of islands and submarines; (ii) Advanced imagining and data analysis including accurate particle imagining velocimetry (PIV) techniques and novel 2D wavelet transforms and interpolation routines for scattered data; (iii) Aerodynamics of small flying devices, especially those where birds and bats coexist in engineering design space. In 2010 he was elected Fellow of the American Physical Society. In 2013 he was awarded the Chaire Joliot at ESPCI, Paris.
“Advanced 3D/4D Bioprinting and Nanomaterials for Complex Tissue Regeneration”
Presented by Professor Lijie Grace Zhang, Department of Mechanical and Aerospace Engineering, the George Washington University
As an emerging tissue manufacturing technique, 3D bioprinting offers great precision and control of the internal architecture and outer shape of a scaffold, allowing for close recapitulation of complicated structures found in biological tissue. In addition, 4D bioprinting is a highly innovative additive manufacturing process to fabricate pre-designed, self-assembly structures with the ability to transform from one state to another directly off the bioprinter. The term “4D” refers to the time-dependent dynamic process triggered by specific stimulation according to predesigned requirements. However, current 3D/4D bioprinting based additive manufacturing technologies are hindered by the lack of advanced smart “inks”. Therefore, the main objective of our research is to develop novel biologically inspired nano or smart inks and advanced 3D/4D bioprinting techniques to fabricate the next generation of complex tissue constructs (such as vascularized tissue, neural tissue and osteochondral tissue). For this purpose, we designed and synthesized innovative biologically inspired nanomaterials (i.e., self-assembly materials, and conductive carbon nanomaterials) and smart natural materials. Through 3D/4D bioprinting in our lab, a series of biomimetic tissue scaffolds were successfully fabricated. Our results show that these bioprinted nano or smart scaffolds have not only improved mechanical properties but also excellent cytocompatibility properties for enhancing various cell growth and differentiation, thus promising for complex tissue/organ regeneration.
Dr. Lijie Grace Zhang is an associate professor in the Department of Mechanical and Aerospace Engineering at the George Washington University. She obtained her Ph.D. in Biomedical Engineering at Brown University. Dr. Zhang joined GW after finishing her postdoctoral training at Rice University and Harvard Medical School. She is the director of the Bioengineering Laboratory for Nanomedicine and Tissue Engineering at GW. She has received the ASME Sia Nemat-Nasser Early Career Award, NIH Director’s New Innovator Award, Young Innovator in Cellular and Molecular Bioengineering, John Haddad Young Investigator Award by American Society for Bone and Mineral Research, and Early Career Award from the International Journal of Nanomedicine, etc. Her research interests include 3D/4D bioprinting, nanobiomaterials, complex tissue engineering and breast cancer bone metastasis. Dr. Zhang has authored 3 books, over 109 journal papers, book chapters and conference proceedings, 6 patents and has presented her work on over 280 conferences, university and institutes. She also serves as the Editor of Materials Science and Engineering C: Materials for Biological Applications; Associate Editor-in-Chief of International Journal of Nanomedicine; and Associate Editor of ASME Journal of Engineering and Science in Medical Diagnostics and Therapy.
“Control of Wind Turbines and Wind Farms”
Presented by Professor Lucy Pao, Electrical, Computer, and Energy Engineering Department, University of Colorado at Boulder
Wind energy is recognized worldwide as cost-effective and environmentally friendly and is among the world’s fastest-growing sources of electrical energy. However, science and engineering challenges still exist. For instance, in order to further decrease the cost of wind energy, wind turbines are being designed at ever larger scales, especially for offshore installations. We will overview a two-bladed downwind morphing rotor concept that is expected to lower the cost of energy more at wind turbine sizes beyond 13 MW compared to continued upscaling of traditional three-bladed upwind rotor designs. We will highlight some of the control systems issues for such wind turbines at these extreme scales and outline selected advanced control methods we are developing to address these issues. In the second part of the talk, we will discuss the growing interest in the coordinated control of wind turbines on a wind farm. Most wind farms currently operate in a simplistic “greedy” fashion where each turbine optimizes its own power capture. Due to wake interactions, however, this greedy control is actually suboptimal to methods in which the collective wind farm is considered. We will overview recent work in wind farm control and show selected results that demonstrate the performance improvements possible when carefully accounting for the wake interactions in coordinating the control of the wind turbines on the farm. We shall close by discussing continuing challenges and on-going and future research avenues that can further facilitate the growth of wind energy.
Lucy Pao is a Professor in the Electrical, Computer, and Energy Engineering Department at the University of Colorado Boulder. She has completed sabbaticals at Harvard University (2001-2002), the University of California, Berkeley (2008), the US National Renewable Energy Laboratory (2009), the Hanse-Wissenschaftskolleg Institute for Advanced Study in Delmenhorst, Germany (2016-2017) and the ForWind Center for Wind Energy Research at Oldenburg University (2016-2017). She earned B.S., M.S., and Ph.D. degrees in Electrical Engineering from Stanford University. Her research has primarily focused on combined feedforward and feedback control of flexible structures, with applications ranging from atomic force microscopy to disk drives to digital tape drives to megawatt wind turbines and wind farms. She is a Fellow of the International Federation of Automatic Control (IFAC) and the Institute of Electrical and Electronics Engineers (IEEE). Selected recent awards include the 2012 IEEE Control Systems Magazine Outstanding Paper Award (with K. Johnson), the 2015 Society for Industrial and Applied Mathematics (SIAM) Journal on Control and Optimization Best Paper Prize (with J. Marden and H. P. Young), the 2017 Control Engineering Practice Award from the American Automatic Control Council, and the Scientific Award 2017 from the European Academy of Wind Energy. Selected professional society activities include being a Fellow of the Renewable and Sustainable Energy Institute (2009-present), General Chair of the 2013 American Control Conference, member of the IEEE Control Systems Society (CSS) Board of Governors (2011-2013 and 2015), IEEE CSS Fellow Nominations Chair (2016-present), and member of the IFAC Executive Board (2017-2020).
“ENABLING ENGINEERED PROPERTIES VIA ARCHITECTURED MATERIALS”
Presented by Professor Jonathan Hopkins, University of California, Los Angeles
Architectured materials (a.k.a. mechanical metamaterials) achieve properties that derive primarily from their microstructure instead of their composition. Preliminary experimental and simulated results obtained from sub-millimeter-sized architectured-material samples show promise for achieving currently unobtainable combinations of super properties that will enable a host of next-generation technologies. The two most significant barriers preventing the practical implementation of such materials, however, include the following:
Professor Hopkins’ Flexible Research Group has focused much of their efforts at UCLA toward overcoming these challenges. This seminar will provide an overview of the design and fabrication tools generated by the Flexible Research Group in the context of practical architectured-material applications. The group’s design tools leverage the simplified mathematics of the Freedom and Constraint Topologies (FACT) synthesis approach to rapidly search the full design space of both periodic and nonperiodic architectured topologies to achieve desired combinations of properties. The group’s fabrication tools utilize custom-developed components (e.g., a flexure-based micro-mirror array) to generate multiple optical traps that are independently controlled to assemble large numbers of different material micro-particles simultaneously for rapidly constructing desired microstructures.
Jonathan Hopkins is an assistant professor at the University of California, Los Angeles and is the director of the Flexible Research Group. The aim of his group is to enable the creation of flexible structures, mechanisms, and materials that achieve extraordinary capabilities via the deformation of their constituent compliant elements. Prior to coming to UCLA, Jonathan was a postdoc at Lawrence Livermore National Laboratory from 2010 to 2013 and received his Ph.D. (2010), Masters (2007), and Bachelors (2005) degrees all in mechanical engineering at the Massachusetts Institute of Technology. He was honored by President Barack Obama at the White House with a DOE nominated PECASE award for his work involving the design and fabrication of architectured materials. Additionally, he is a recipient of ASME’s 2016 Freudenstein/General Motors Young Investigator Award, the V.M. Watanabe Excellence in Research Award, and the Northrop Grumman Excellence in Teaching Award.