2013 Seminar Archive


Spring, 2013

A Taste of SUGAR (Subsonic Ultra Green Aircraft Research)
Results of the Boeing Study for NASA for Future Commercial Aircraft Concepts & Technologies

Marty Bradley

Technical Fellow
The Boeing Company
Long Beach, CA

This seminar summarizes the work accomplished by the Boeing Subsonic Ultra Green Aircraft Research (SUGAR) team in a NASA study looking at future concepts and technologies for commercial aircraft in the 2030-2035 timeframe.

The team developed a comprehensive future scenario for world-wide commercial aviation, selected baseline and advanced configurations for detailed study, generated technology suites for each configuration, conducted detailed performance analysis, calculated noise and emissions, assessed technology risks and payoffs, and developed technology roadmaps for key technologies.

Advanced aircraft configurations evaluated in the study included high span strut-braced wings and blended wing bodies (BWB’s). A wide portfolio of technologies was identified and evaluated to address the NASA goals. High payoff technologies included hybrid-electric gas turbine battery propulsion, low-NOx combustors, biofuels, advanced air traffic management, noise treatments, laminar flow, and materials.

Compared to today’s aircraft, fuel burn reductions of up to 55% were achieved. The additional of hybrid electric propulsion may allow reductions of up to 90%. Significant reductions in emissions, noise, and runway length were also achieved and will be discussed.

Wednesday, November 10, 2010
3:30 PM
Stauffer Science Lecture Hall, Room 100 (SLH 100)

Refreshments will be served at 3:15 pm.

Modeling the Internal Weather in Lakes

Larry G. Redekopp

Professor
Department of Aerospace & Mechanical Engineering
University of Southern California
Los Angeles, CA

This lecture will address issues pertaining to the modeling of the internal (subsurface) weather in enclosed, or semi-enclosed, basins under mid-summer conditions. An understanding of, and an ability to predict, the internal dynamics of stratified lakes is central to the management of many water resources, particularly the quality of potable and recreational resources. The internal bio-geochemical quality of a lake depends crucially on the hydrodynamic processes whereby energy input at the basin scale via solar insolation and surface wind stresses is transferred down to mixing and dissipation scales. It is important to build tools that model the internal weather in closed basins with reasonable fidelity for purposes of both gaining a general qualitative understanding of lake hydrodynamics and for providing quantitative estimates of space-time scales for energy transfer routes and particulate transport paths.

The lecture will address several ‘rapid-simulation’ models relevant to small and moderate sized, stratified lakes in which an evolving, energetic, internal wave field is excited by surface wind events. Models of the degeneration of the wind-driven, basin-scale, internal seiche into a field of bi-directional, propagating internal waves for several lake configurations will be discussed, including the role of the evolving internal wave field in both the stimulation of benthic boundary eruptions and the dispersion of toxic spills in a moderately-sized lake.

Wednesday, January 30, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Nanoparticles: Transport Theory, Flame Synthesis and Selected Applications

Hai Wang

Professor
Department of Aerospace & Mechanical Engineering
University of Southern California
Los Angeles, CA

Synthesis of metal oxide nanoparticles in premixed stagnation flames offers significant advantages over other flame methods. Particles produced usually have good crystallinity, high phase purity, and narrow and controllable size distributions. Past studies have shown that when the stagnation surface is translated relative to the flame sheet, particle synthesis and film deposition can be achieved in a single step. The technique enables high-throughput film deposition and is scalable with respect to the deposition area. The first part of this talk will be on the stagnation flame technique for preparation of phase-pure titania nanoparticle films for applications in dye sensitized solar cells and for conductometric CO sensing.

It was recognized that a fine control of the particle property requires a rather precise knowledge about the time-temperature history of the particles behind the flame. Determined by the drag and thermophoretic forces acting on the growing cluster and nanoparticles, this history dictates the particle nucleation and size growth environment and time. This motivated us to re-examine the transport theories of nanoparticles in dilute gases. Through a gas-kinetic theory analysis, we obtained mathematical formulations for these forces in two limiting models of gas-particle interactions: specular and diffuse scattering. It has been shown that our expressions are more fundamental than the earlier Epstein expressions, and they offer the possibility of a unified description of particle transport, from molecules to cluster and nanoparticles. The origin of diffuse scattering has been explained by molecular dynamics. The remaining problem lies in a missing first-principle based description for the transition from elastic specular scattering to inelastic diffuse scattering at several nanometers of particle size, as will be discussed in detail.

Wednesday, February 6, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

How to Build a Jellyfish: Translating Biological Mechanisms for Fluid Transport to Engineered Materials

Janna Nawroth

Postdoctoral Researcher
California Institute of Technology
Pasadena, CA

Insights into biological mechanisms for fluid transport have the potential to advance technology for robotics and medical implants. A major challenge is to link structure to function, i.e., to understand and replicate the dynamic interactions between living cells, elastic substrates, and the fluid environment. My approach is to learn from the design of simple aquatic invertebrates that pump, filter, and mix fluid across a wide range flow regimes. In a proof-of-concept study I have reverse-engineered a juvenile jellyfish, a model system for muscle powered pumps at intermediate Reynolds numbers. Using an iterative optimization strategy, I identified key determinants of propulsive and feeding performance in jellyfish, including actuator layout, substrate elasticity, and body geometry, and translated them to tissue-engineered materials. Constructs were assembled by seeding rat cardiac muscle cells onto flow-optimized silicone bodies. Guided by microfabricated surface cues, the cells self-organized into a swimming muscle capable of synchronous contraction. Optimally designed constructs achieved propulsion and generated “feeding” currents quantitatively and qualitatively comparable to real jellyfish. I will summarize the design lessons learned in the process and discuss general implications for tissue-engineering and soft robotics.

Janna Nawroth completed her undergraduate studies in Molecular Biotechnology and Bioinformatics at the University of Heidelberg, Germany. Prior to joining the PhD program in biology at Caltech, she spent two years at the Yale school of Medicine conducting master’s degree research in neuroscience. She received her PhD degree in 2012 from Caltech where she was co-advised by both John Dabiri at Caltech and Kit Parker at Harvard University while conducting cross-disciplinary research on design and fabrication of muscle-powered fluid pumps. She is currently a post-doctoral researcher in the Dabiri lab, working on neuronal control and fluid transport in marine invertebrates such as squid and jellyfish.

Wednesday, February 13, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Micron-Scale Carpets: The Optimal Hydrodynamics of Cilia

Eric Lauga

Associate Professor
University of California, San Diego
Department of Mechanical and Aerospace Engineering
La Jolla, CA 92093-0411

The world of self-propelled low-Reynolds number swimmers is inhabited by a myriad of microorganisms such as bacteria, spermatozoa, ciliates, and plankton. In this talk, we focus on the locomotion of ciliated cells. Cilia are short slender whiplike appendages (a few microns long, one tenth of a micron wide) internally actuated by molecular motors (dyneins) which generate a distribution of bending moments along the cilium length and produce time-varying shape deformations. In most cases cilia are not found individually but instead in densely packed arrays on surfaces. In this talk we will ask the question: can the individual and collective dynamics of cilia on the surface of an individual microorganism be rationalized as the solution to an optimization problem? We first address the deformation of individual cilia anchored on surfaces before characterizing the locomotion and feeding by surface distortions of swimmers covered by cilia array. We demonstrate, as solution to the optimization procedure, the appearance of the well-known two-stroke kinematics of an individual cilium, as well as waves in cilia array reminiscent of experimentally-observed metachronal waves.

Wednesday, February 27, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Manipulating Light with Novel Optical Materials and Structures

Jie Yao

Postdoctoral Researcher
Materials Science and Engineering Department
Stanford University
Stanford, CA

Manipulation of light is of great importance for both research and industrial applications. It is realized through the interaction between light and matter. Therefore investigation of the interaction mechanism and design of novel optical materials and structures have become a vital part of scientific and engineering research. Here I will demonstrate my discoveries of the first visible light negative refraction, 3-dimensional deep-subwavelength optical cavity and extraordinary optical transmission based on different categories of novel optical materials, including metamaterials, naturally formed 2D structures. On the other hand, conventional materials with innovative structural designs can also provide new opportunities. I will discuss my work on silicon nanostructures that greatly improved the light trapping capability for energy harvesting purposes. Novel designs of optical materials and structures are enhancing our understanding of light–matter interaction mechanism and leading to new applications of light manipulation.

Jie Yao is a Postdoctoral Researcher in the Materials Science and Engineering Department at Stanford University. He holds a PhD in Applied Science and Technology from UC Berkeley. His research interests include metamaterials design and applications, light management for energy conversion, optomechanics and optical nano-cavities. He has demonstrated for the first time the negative refraction of visible light in bulk metamaterials, which promotes the research of metamaterials and potential applications such as invisible cloaks. He also designed and demonstrated the world’s smallest three-dimensional indefinite optical cavities. His work was among the top 10 scientific discoveries of the year 2008 selected by TIME magazine.

Wednesday, March 6, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

NanoEngineering for High Performance Devices and Highly Efficient Energy Systems

Yongjie Hu

Postdoctoral Fellow
Department of Mechanical Engineering
Massachusetts Institute of Technology

In our everyday devices, about 60% of the primary energy is lost when converted from one form to another during operation. Nanotechnology holds the promise of dramatically improving device performance and energy efficiency. In this talk, I will discuss our efforts in engineering fundamental energy carriers at the nanoscale, in particular, for solid-state energy conversion, high-performance electronics and coherent quantum computation. First, I will present our recently developed hybrid nanostructures engineered to characterize nanoscale thermal transport. I will discuss how we can independently control the heat flow in a rationally designed path and selectively detect the local temperature. Coupling the system with ultrafast optical spectroscopy and modeling, we determined the mean free path dependent thermal conductivity in different materials. Our approach can serve as generic metrology for high throughput screening of energy materials and as a guidance tool for next-generation energy device design through phonon engineering.

Second, I will present a novel material system achieved through bottom-up chemical synthesis and band structure engineering design. I will discuss our work in building high-performance electronics and integrated circuits, where the developed transistors outperformed the state-of-the-art MOSFETs and can also be applied for nano-bio interfaces. I will then talk about our development of a highly sensitive charge sensor integrated with coupled quantum dots, and show that we demonstrated full control and detection over charge dynamics, inter-coupling and lifetimes with GHz pulse manipulations. Finally, I will show that we developed the first long coherent Quantum Bit in Group-IV materials, which encodes information in the smallest energy quanta, spin, for next generation of efficient computation. We believe our efforts in developing new functional nanomaterials and structures will lead to advanced energy-conversion and device-operation paradigm in the future.

Yongjie Hu is currently the Battelle/MIT Postdoctoral Fellow in the Mechanical Engineering Department of the Massachusetts Institute of Technology with Professors Gang Chen and Mildred Dresselhaus, focusing on material optimization and device design for thermal transport and solar energy conversion. He obtained his M.A. (2006) and Ph.D. (2010) from Harvard University with a research focus in the areas of nanotechnology, including nanomaterials synthesis, structure characterization, high-performance devices and transport physics under the supervision of Professor Charles M. Lieber. Dr. Hu is a recipient of Micro & Nano: Heat Transfer Division Award from ASME (2012), Battelle/MIT Fellowship from MIT (2012), China’s National Award for Outstanding Students Studying Abroad (2011) and Fieser Fellowship from Harvard University (2004, 2005).

Monday, March 11, 2013
3:30 PM
Hedco Neurosciences Building, Room 100 (HNB 100)

Refreshments will be served at 3:15 pm.

Design, Fabrication, and Control of Flapping-Wing Flying Artificial Insects

Néstor O. Pérez-Arancibia

Postdoctoral Fellow
Harvard University
Cambridge, MA

In this talk, I will discuss the theoretical and experimental challenges that arise in the design, fabrication, and control of biologically inspired at-scale flapping-wing flying robotic insects. In the course of the research presented in this talk, analytical and experimental tools were developed for extracting the relevant dynamics of flapping-wing mechanisms from a systems-and-control perspective. Then, the estimated dynamics were used for developing new robotic designs and fabrication methods in order to obtain better flying prototypes, and for devising flight control strategies in one degree of freedom (altitude). Finally, the proposed approach was extended to other degrees of freedom and to the multiple-input-multiple-output case with the purpose of creating the flying prototypes and control strategies that allowed us to achieve the first unconstrained controlled flight of a flapping-wing artificial insect of this size (< 100 mg).

Néstor O. Pérez-Arancibia is a postdoctoral fellow with the Microrobotics Laboratory and with the Wyss Institute for Biologically Inspired Engineering at Harvard University. His current research focuses on the design and development of control systems for biologically inspired at-scale flying robotic insects. Since April of 2010, he has been part of the team working on the design, fabrication, and control of flapping-wing microrobots, toward the goal of creating a completely autonomous sub-gram flapping-wing flying robot by 2014, as part of the NSF Expeditions in Computing RoboBees project. Dr. Pérez-Arancibia received his Ph.D. from the Mechanical and Aerospace Engineering Department at the University of California, Los Angeles (UCLA) in 2007. From October 2007 to March 2010 he was a Postdoctoral Scholar with the Laser Beam Control Laboratory and also with the Mechatronics and Controls Laboratory at UCLA.

Wednesday, March 13, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Non-Equilibrium Plasma-Assisted Combustion for Advanced Energy Conversion and Propulsion

Wenting Sun

Postdoctoral Researcher
Mechanical and Aerospace Engineering
Princeton University
Princeton, NJ

About 85% of the energy in the world is produced by the combustion of fossil fuels. However, the growing concerns about emissions, and the development of advanced energy conversion and propulsion systems have pushed traditional combustion technology to challenging limits. To continue to develop these technologies, it is critical to develop new approaches to improve the performance of combustion. This presentation will discuss controlling combustion kinetics using non-equilibrium plasmas – plasma-assisted combustion. Plasma introduces new chemical pathways into the combustion process. This plasma chemistry occurs on very different time scales compared to conventional combustion chemistry and also introduces a large number of new species and reactions which have not been previously considered in combustion research.

The kinetic enhancement mechanisms of non-equilibrium plasmas on combustion are investigated through plasma-flame interactions in counterflow systems. It is found that the radical production from the plasma can dramatically modify the reaction pathways of combustion to create a new flame region at low temperatures. Advanced laser diagnostic techniques are used to quantify radical (atomic O and OH) productions from plasmas. Both experimental and simulation results show that atomic O is critical in controlling fuel oxidation at low temperature conditions.

Wenting Sun is currently a postdoctoral researcher of Mechanical and Aerospace Engineering at Princeton University. He received his B.E/M.E degrees from Tsinghua University, Department of Engineering Physics in 2005 and 2007, respectively, and Ph.D degree from Princeton University, Department of Mechanical and Aerospace Engineering in 2013. His current research focuses on plasma-assisted combustion, laser diagnostics, and combustion kinetics for advanced energy conversion and propulsion systems. He also works on numerical modeling of reacting flows, chemical kinetic mechanism reduction, and high pressure plasma technology. He has been awarded the Bernard Lewis Fellowship from the Combustion Institute, the Britt and Eli Harari Fellowship and the Guggenheim Fellowship from Princeton University, and Distinguished Paper Award at the 33rd International Symposium on Combustion.

Monday, March 25, 2013
3:30 PM
Hedco Neurosciences Building, Room 100 (HNB 100)

Refreshments will be served at 3:15 pm.

Part I: Aquatic Propulsion and Wake Signatures at Re = [1,1000]

Jeannette Yen

Director
Center for Biologically Inspired Design
Georgia Institute of Technology
Atlanta, GA

Plankton are aquatic organisms that form the base of the aquatic food web and therefore, aquatic ecosystem balance depends on their survival. Plankton operate at intermediate Reynolds numbers, generating watery signals that can be attenuated by viscosity and confused with small-scale turbulence. Yet messages are created, transmitted, perceived and recognized. These messages guide essential survival tasks of aquatic organisms. At the small-scale where biologically-generated behavior differs from physically-derived flow, we find plankton self-propel themselves, are aware of each other, and evolve in response to the fluid environment in surprising ways.

Jeannette Yen is the Director of the Georgia Institute of Technology’s Center for Biologically Inspired Design (CBID). The goals of CBID are to bring together a group of interdisciplinary faculty who seek to facilitate interdisciplinary research and education for innovative products and techniques based on biologically-inspired design solutions. The participants of Georgia Tech’s CBID believe that science and technology are increasingly hitting the limits of approaches based on traditional disciplines, and Biology may serve as an untapped resource for design methodology, with concept-testing having occurred over millions of years of evolution. Experiencing the benefits of Nature as a source of innovative and inspiring principles encourages us to preserve and protect the natural world rather than simply to harvest its products. Jeannette team-teaches the interdisciplinary course in biologically inspired design.

Part II: What Do Crabs Know, and What Can They Teach Us?

Marc Weissburg

Professor of Biology and Co-Director of CBID
Center for Biologically Inspired Design
Georgia Institute of Technology
Atlanta, GA

We currently lack strategies by which we can implement autonomous chemically-guided navigation in remotely operated or fully independent vehicles. Although this ability would be useful for a variety of purposes, a primary stumbling block is we don’t have robust, computationally efficient and adaptive algorithms for encoding information in turbulent chemical plumes. Animals, of course, do this extremely well. I will describe how we have used 3D laser fluorescence measurements around freely navigating animals to analyze the information content of turbulent chemical plumes and understand strategies to encode this information. I will discuss current efforts to develop adaptive and robust algorithms using biological principles and present some tests of our ideas on both hardware and simulations.

Marc Weissburg is Professor of Biology and Co-Director of the Center for Biologically Inspired Design. He is an ecologist/sensory biologist who examines the mechanisms and consequences of information transfer via aquatic chemical signals. He uses multidisciplinary approaches and field ecological investigations to study the structure of aquatic plumes and the dynamics of fluids in the marine environment and to behaviorally analyse the sensory strategies of aquatic organisms and their capability to rely on turbulent chemical plumes for guidance and navigation. He has used biological principles to devise artificial sensory processing strategies for autonomous navigation in chemical plumes. He has applied principles of ecological organization to human infrastructure in his search for more sustainable practices. He has co-taught Biologically Inspired Design for seven years to a variety of audiences ranging from undergraduates to professional engineers and scientists.

Wednesday, March 27, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Understanding Materials Dynamics under Rapid Impulsive Loading

Yogendra M. Gupta

Regents Professor of Physics
and
Director of Institute for Shock Physics
Department of Physics and Institute for Shock Physics
Washington State University
Pullman, WA 99164

Dynamic compression experiments (~5 to 200 GPa) subject materials to large compressions, deformations, and high temperatures on very short time scales (ps to μs) resulting in a rich array of physical and chemical changes. Credibly linking and understanding the dynamic response of materials in real-time across different length scales constitutes the major scientific challenge in the field. After a brief introduction about shock wave compression, this talk will summarize recent research activities, experimental developments, and future opportunities to understand condensed matter dynamics at high stresses and short times.

Yogendra M. Gupta, Regents Professor in the Department of Physics and Director of the Institute for Shock Physics, has been a faculty member at Washington State University (WSU) since 1981. Prior to his appointment at WSU, he spent nearly seven years at the Stanford Research Institute (now SRI International) preceded by two years of postdoctoral research. Since 1970, Gupta has been engaged in experimental and theoretical research related to shock wave and high pressure compression of condensed matter. His work has emphasized real-time examination and understanding of microscopic processes using a variety of time-resolved measurements and related analyses (optical spectroscopy, x-ray diffraction, and several continuum methods) in a wide range of materials. Gupta and his collaborators have worked on a broad range of condensed matter phenomena: structural transformations, chemical reactions, and deformation and fracture. These studies have resulted in over 275 publications. Currently, Professor Gupta is leading a major experimental effort to establish the Dynamic Compression Sector at the Advanced Photon Source (Argonne), a DOE/NNSA supported user facility. Since joining WSU, he has supervised the work of more than 100 graduate students and research associates. Professor Gupta is a Fellow of both the American Physical Society (1991) and the American Association for the Advancement of Science (2002), and has served on numerous committees related to U.S. national security programs. In 2001, he received the American Physical Society’s Shock Compression Science Award, the premier award in the field. In 2005, he was the recipient of Washington State University’s highest faculty recognition, the Eminent Faculty Award.

Wednesday, April 3, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Control of Multi-Vehicle Systems

Dušan M. Stipanović

Associate Professor
Department of Industrial and Enterprise Systems Engineering
and
Control and Decision Group at the
Coordinated Science Laboratory
University of Illinois at Urbana-Champaign
Urbana-Champaign, IL

In this talk, a number of control designs for controlling multi-vehicle systems will be presented. These control designs highly depend on the type of vehicles which are controlled such as differential drives, cars, helicopters or quadrotors. They also depend on the information that is available to vehicles and vehicles’ objectives to be accomplished as well as various uncertainties including perturbations and delays. In addition to some simulation results a number of experimental results including autonomous and semi-autonomous (that is, teleoperated) ground vehicles (conducted in Mechatronics and Robotics Laboratories at the University of Illinois) and aerial vehicles (in collaboration with the Boeing Company) will be presented.

Friday, April 5, 2013
2:00 PM
Kaprillian Hall, Room 144 (KAP 144)

Computational Modeling of Amorphous and Crystalline Materials

Eric R. Homer

Assistant Professor
Dept. of Mechanical Engineering
Brigham Young University
Provo, UT

While the atomic-level processes regarding material behavior are often known, translating this knowledge to understand and predict material behavior at the macroscale can be a significant challenge. As such, computational materials modeling has emerged as a particularly useful tool to aid in the advancement of engineering materials. The work to be presented includes efforts to elucidate the phenomena controlling the mechanical behavior of amorphous metals as well as a method to simulate coupled compositional-microstructural evolution in crystalline materials.

Amorphous metals exhibit mechanical properties superior to their crystalline counterparts in many cases, but suffer from an inherent lack of ductility. This work provides new understanding of the shear localization process that ultimately leads to catastrophic failure. The insight is achieved through a through a new mesoscale model of amorphous metals that is capable of accessing experimentally relevant timescales. Additionally, a new Potts-Phase Field model for coupled composition-microstructure evolution is presented. The coupled model provides simultaneous evolution of grain structure and composition in a computationally efficient manner and promises to provide new insight into nuclear fuels research.

Eric R. Homer is an assistant professor in the Department of Mechanical Engineering at Brigham Young University. He received B.S. and M.S. degrees in Mechanical Engineering from Brigham Young University in 2006 and a Ph.D. in Materials Science & Engineering from Massachusetts Institute of Technology in 2010. Prof. Homer then spent one year as a postdoctoral appointee in the Computational Materials Science & Engineering at Sandia National Laboratories, Albuquerque, NM. He has 13 publications in the areas of the mechanical behavior of amorphous metals, microstructure characterization, atomic simulations and microstructural modeling.

Wednesday, April 17, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Oscillators, Synchronization and Signal Processing

Prashant Mehta

Dept. of Mechanical Science & Engineering
Coordinated Science Laboratory
University of Illinois at Urbana-Champaign
Urbana, IL

Inference (prediction) is believed to be a fundamentally important computational function for biological sensory systems. For example, the Bayesian model of sensory (e.g., visual) signal processing postulates that the cortical networks in the brain encode a probabilistic belief about reality. The belief state (modeled as a posterior distribution in the Bayes’ formalism) is updated based on comparison between the novel stimuli (from senses) and the internal prediction.

A natural question to ask then is whether there is a rigorous methodology (and algorithms) to implement complex forms of prediction (via Bayes theorem) at the level of neurons—the computing elements of the brain? In this talk I will provide a qualified answer to this question based on a coupled oscillator feedback particle filter model. A single oscillator is a simplified model of a single spiking neuron, and the coupled oscillator model solves an inference problem. The methodology will be described with the aid of a model problem involving estimation of a “walking gait cycle.”

The talk will also delve into some recent algorithmic advances in the area of nonlinear filtering (estimation), which may be of independent interest to signal processing and control theory aficionados.

This work is the result of collaboration with Professor Sean Meyn, and with several students at the University of Illinois.

Prashant Mehta is an Associate Professor in the Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign. He received his Ph.D. in Applied Mathematics from Cornell University in 2004. Prior to joining Illinois, he was a Research Engineer at the United Technologies Research Center (UTRC). His research interests are at the intersection of dynamical systems and control theory, including nonlinear filtering, mean-field games, model reduction, and nonlinear control.

He has received several awards including an Outstanding Achievement Award for his research contributions at UTRC, several Best Paper awards with his students at Illinois, and numerous teaching and advising honors at Illinois.

Wednesday, April 24, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Optogenetic Control of Epileptic Seizures

Andrew J. Szeri

Professor
Center for Neural Engineering and Prostheses
Department of Mechanical Engineering
University of California, Berkeley
Berkeley, CA
and
Dean of the Graduate Division
University of California, Berkeley

We begin with a brief introduction to the subject. Then, using a mesoscale, stochastic, partial differential equation mathematical model of cortical dynamics, we investigate the potential for various control strategies to ameliorate seizures for patients with epilepsy that does not respond well to pharmacological treatment. The modalities we explore in this talk include our prior work on use of charge balanced electrical feedback control, and new work on the use of actuation by optical stimulation of neurons that have expressed light-activated ion channels in the cell membrane as a consequence of genetic manipulation. We study the ways these approaches work through control of bifurcations in the underlying mathematical models.

Andrew J. Szeri earned his PhD at Cornell University in 1988. Following post-doctoral appointments at CalTech and UC Santa Barbara, and a faculty position at UC Irvine, he moved to Berkeley in 1997. Professor Szeri’s research interests include convective/diffusive transport and nonlinear dynamics, with applications principally drawn from medical treatments and devices. Recent work has focused on nonlinear dynamics of sleep and seizures, high intensity focused ultrasound (HIFU) treatment of blood clots in the brain, anti-HIV vaginal microbicides, shock wave lithotripsy and oxygen transport in blood substitutes.

Wednesday, May 1, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.


Fall, 2013

Cancer Metabolism and the Origin of Multicellularity

Luis Cisneros

Postdoctoral Scholar
Center for the Convergence of Physical Science and Cancer Biology
Arizona State University
Tempe, AZ

Cancer represents a breakdown of the normal relationship between somatic and germ cells. It has been suggested (Rainey and Kerr, 2010) that the transition from a single-celled world to reproductive assemblages is facilitated by the onset of defectors that flourish at the expense of the collective. If so, cancer could be a fundamental process, a necessary part in the profound relationship between selfish cells and cooperating communities leading to this momentous evolutionary step. Therefore cancerous “cheats” may play a major role in the origin of cooperative aggregates and the subsequent emergence of fully multicellular life. We use an agent-based model of interacting cells that switch between a reproductive phase and a non-reproductive cooperative phase to explore this hypothesis. Individual dynamics of cells are defined by their metabolic strategies, simplified in a model that captures the tradeoff between rate and efficiency of energy production and anabolic growth. Mode selection depends on the conditions of the local environment but also ultimately modify it. The transition to cooperative behavior, consisting of the formation of aggregates that have a primitive reproductive capacity, emerges as a product of the environmental feedback and selection for fast replication or longevity at different time scales.

Wednesday, September 4, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Numerical Modeling of Complex Fluids With a Geological Perspective

Louis Moresi

Professor
School of Mathematical Sciences
Monash University
Clayton, Australia

Geological materials (rocks), deform on very long timescales as viscoelastic/plastic solids, particularly in the upper 100km of the Earth where the temperature is relatively low. Strain localisation is ubiquitous—though many different underlying mechanisms may be responsible. Furthermore, rocks capture their strain-history for very long times (even as much as a billion years).

The surface evolution of the Earth is driven by loss of deep heat which drives very large scale convection currents and movement of the surface tectonic plates. To understand this basic geological process demands large-scale numerical models with some unusual techniques.

I will describe the background computational methodology for planetary-scale fluid / solid mechanics and explain how such techniques could be useful in diverse fields such as mould-filling, food processing, civil engineering, and geomechanics.

Wednesday, September 11, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Harder, Cheaper, Greener: the Design and Deployment of Alloy Coatings with Stabilized Nanocrystalline Structures

Christopher A. Schuh

Danae and Vasilis Salapatas Professor of Metallurgy
and
MacVicar Fellow
Department of Materials Science and Engineering
Massachusetts Institute of Technology
Cambridge, MA

When the grain size of a metal is refined to a scale on the order of just a few nanometers, its strength, hardness, wear resistance, and other properties improve in dramatic ways. There is therefore significant interest in designing and deploying such nanocrystalline alloys for structural applications. However, refining the grain structure is a struggle against equilibrium, and nanocrystalline materials are often quite unstable; the grains grow given time even at room temperature, and the associated property benefits decline over time in service. In this talk, our efforts to design a stable family of nanocrystalline alloys will be described. We rely on selective alloying as a method to lower the energy of grain boundaries, bringing the nanocrystalline structure closer to equilibrium. Using analytical thermodynamic mixing calculations and Monte Carlo simulations, we identify desirable alloying elements for a given base metal, and assess the relative stability of nanocrystalline structures against grain growth. We then transition these modeling principles to the laboratory, produce materials, and experimentally validate the modeling results. Finally, the talk will review the connection between theory, experiment, and engineering application, and describe a suite of commercial products based on this research.

Wednesday, September 18, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Not Just Noise: Suppressing Separation with Sound

Chiara Bernardini

Visiting Scholar
Department of Mechanical and Aerospace Engineering
The Ohio State University
Columbus, OH

The natural shear layer instability occurring in separating flows can be exploited as an effective mechanism for flow control. Acoustic excitation is a suitable tool to study the control effectiveness of single frequency perturbations with no local introduction of momentum into the boundary layer.

First, exploitation of linear instability mechanisms for separation control is experimentally investigated by means of acoustic excitation on a front-loaded low-pressure turbine blade experiencing a separation bubble at low Reynolds numbers. Acoustic forcing at the most unstable frequency of the separating shear layer is able to overcome separation with small excitation amplitude due to linear amplification of perturbations. However this mechanism fails to significantly reduce separation loss when applied to large open separation due to a strong adverse pressure gradient. Nevertheless another efficient mechanism can be exploited by single frequency excitation, which is shown to be non-linear vortex merging promoted by forcing in the range of the subharmonic of the fundamental frequency of the shear layer.

Acoustic excitation is then used to understand the role of instabilities in flow control by pulsed jets. The physics of control by pulsed blowing on a NACA 643-618 natural laminar flow airfoil is studied using hot film anemometry. Measurements in the uncontrolled separated shear layer indicate that vortex shedding is taking place due to the Kelvin-Helmholtz type inviscid instability. Steady and pulsed external acoustic excitation is used as well to decouple frequency content of the perturbation from the vorticity introduced by the jet. Acoustic control introduces either the most unstable frequency or harmonics of carrier frequency in the most unstable range, which amplify exponentially in the separation region yielding a significant delay of the separation location. Experimental data suggests that pulsed jets introduce higher order harmonics of the low frequency pulsing as well, amplifying natural disturbances in the laminar separation. Phase averaged wavelet analysis is used to study the control physics within a single pulsing period.

Chiara Bernardini obtained her PhD at the Department of Energy Engineering, University of Florence, Italy, focusing on computational fluid dynamics for turbomachinery. Since 2011 she has been a visiting scholar at the Department of Mechanical and Aerospace Engineering at The Ohio State University, working under the supervision of Dr. J. P. Bons and Dr. J.-P. Chen. She is carrying out experimental research on flow control for turbomachinery and airfoils.

Wednesday, September 25, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

3D Printing: From Rapid Prototyping to Rapid Manufacturing and Future Opportunities

Yong Chen

Associate Professor
Epstein Department of Industrial and Systems Engineering
University of Southern California
Los Angeles, California

The advent of 3D printing/additive manufacturing and its use in rapid prototyping has drastically changed the design and manufacturing landscape by enabling companies to prototype and produce products faster and cheaper. With the price of these technologies dramatically dropping in recent years, their accessibility is on the increase. However, significant challenges remain to be addressed in the future 3D printing development in order to achieve direct digital manufacturing for future engineering systems. This talk will provide an overview of 3D printing technology and discuss some of its benefits including unlimited geometric capability and heterogeneous material property. Some limitations and challenges of the technology for rapid manufacturing will be discussed. Recent research work for addressing them will also be discussed. The talk will conclude with remarks and thoughts on future research opportunities and potential applications.

Yong Chen obtained his Ph.D. degree in Mechanical Engineering from Georgia Institute of Technology in 2001. Prior to joining USC in 2006, he was a senior engineer at 3D Systems Inc. His research focuses on digital design and manufacturing and related modeling, analyzing, synthesizing, and optimizing methods. He received the NSF CAREER Award and multiple Best/Outstanding Paper Awards in major design and manufacturing journals and conferences.

Wednesday, October 2, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Granular Flows and Martian Gullies

Jim McElwaine

Professor
Department of Earth Sciences
University of Durham
Durham, England

Dense granular flows occur frequently in both nature and industry, yet, despite their prevalence, they remain poorly understood. Most theories are empirically based and are unreliable when applied outside their narrow range of validity. For terrestrial phenomena this is only an inconvenience as more detailed experiments always be performed. For extra-terrestrial phemomena however this is largely impossible and likely to remain so. For this reason it is essential to develop physically based theories that can be applied throughout the solar sytems where gravity, air pressure and temperature may have very different values. I report on chute and drum experiments of granular flows and explain how these observations are applicable in interpreting observations. As a case study I focus on the flow of carbon dioxide blocks down Martian dunes.

Wednesday, October 16, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

State-of-the-Art Experiments to Solve Problems in Combustion, Propulsion, and Environmental Systems

Subith S. Vasu

University of Central Florida
Orlando, FL

The first part of this talk will describe using shock tube and laser absorption methods to investigate the oxidation of various hydrocarbon fuels that are relevant to advanced combustion and propulsion systems under practical conditions. The strategy of using shock tubes provide an ideal device for acquiring ignition delay times and species concentration time-histories, while laser-based diagnostic studies are non-intrusive, provide in-situ measurements (e.g., concentration of individual species including trace species, and temperature), and have fast-time response (micro-second). Recent measurements during butanol combustion, a very important emerging biofuel, will be discussed. The second part of the talk will present state-of-the-art experimental tools – photoionization mass spectrometry using tunable vacuum-ultraviolet synchrotron radiation – to the combustion of next-generation biofuels that may be efficiently produced from biomass by endophytic fungi. The collaborative biofuel development framework in which the PI is an active member, synthetic biologists develop and engineer a new platform for drop-in fuel production from lignocellulosic biomass, using several endophytic fungi including Gliocladium roseum. The combustion researchers investigate the fundamental chemistry of compounds produced by synthetic biologists and recommend potential candidates to test in clean high-efficiency advanced homogeneous charge compression (HCCI) engines. This information is then used to construct predictive combustion chemistry models to guide the optimization towards high-performance compounds and recommendations are provided for the bioengineering scale-up of specific metabolic pathways. The third part of the talk will focus on a recent breakthrough research achievement in solving the mysterious Criegee intermediates — carbonyl oxides – which are implicated in autoignition chemistry and are pivotal atmospheric reactants, but only indirect knowledge of their reaction kinetics had previously been available. Although decades of theoretical studies and indirect experimental evidence support the importance of Criegee radicals in the troposphere, the quantitative effects of their chemistry remained uncertain (until this landmark work) because it had been impossible to make direct measurements of Criegee reactions with key atmospheric species.

Wednesday, October 23, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Toward Integrated Design Methods for Active Dynamic Systems

James T. Allison

Assistant Professor
Industrial and Enterprise Systems Engineering
University of Illinois at Urbana-Champaign
Urbana, IL

The importance, complexity, and demands on actively controlled engineered systems are increasing rapidly, motivating deeper understanding of how to design these systems successfully. Traditionally, active systems are designed using a sequential process where control system design is performed after physical system design is complete. This compartmentalized approach supports deep design expertise in the physical and control system domains, but cannot fully account for the strong interactions across these domains. As a result, sequential methods cannot generate system-optimal designs. In especially demanding design problems, sequential methods may even fail to meet system design requirements. Conventional sequential design methods may fail to keep pace with the intensifying demands for active and autonomous systems. More integrated approaches are needed that deal directly with the sometimes non-obvious interactions between physical and control system design. Optimization-based co-design methods have emerged as a promising integrated approach, often leading to dramatically improved system performance. This presentation will include discussion of several specific co-design studies, as well as discussion of ongoing research efforts that address new methods for dynamic system architecture design based on generative algorithms.

Prof. James Allison (Industrial and Enterprise Systems Engineering, UIUC) is the director of the Engineering System Design Lab, which concentrates on the development and investigation of quantitative design methodologies for engineering systems, with emphasis on the design of complex dynamic systems. Application domains studied by his research group include sustainable energy systems (wind and wave energy), electric and hybrid electric powertrains, robotics, structural systems, material design, and synthetic biology. Prof. Allison holds a Ph.D. Mechanical Engineering (University of Michigan, 2008). He is the co-author of over 30 publications and the recipient of several awards, including the 2013 ASME Design Automation Young Investigator Award and an NSF Graduate Research Fellowship. Previous experience includes several years of industry experience in the automotive (Ford and GM) and the engineering software (MathWorks) industries, as well as other academic positions (part-time faculty at Tufts University, postdoctoral research fellow at the University of Michigan).

Wednesday, November 6, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Pushing the Boundaries: The Fluid Dynamics and Structural Mechanics of Detonation Wave Reflection

Joseph E. Shepherd

C. L. “Kelly” Johnson Professor of Aeronautics
and
Professor of Mechanical Engineering
and
Dean of Graduate Studies
California Institute of Technology
Pasadena, CA

One of the issues encountered in industrial safety and mechanical design of processing facilities is the propagation of detonation and shock waves inside piping systems filled with explosive gases. Over the last two decades, experimental and computational research has been carried out at Caltech on various aspects of this problem. Following a brief discussion of some motivating issues in nuclear waste storage, processing, and nuclear power plant safety, I will describe some key results of our studies. The emphasis is on physical explanations of experimental findings using ideas from fluid dynamics and structural mechanics. Some basic ideas about explosions and structural response of piping systems will be described followed by an in-depth discussion of the results of our experiments on the elastic and plastic deformation of piping due to detonation reflection from a closed end. Three very surprising experimental results will be presented and explained: 1) the occurrence of a spatially-periodic permanent deformation; 2) an inconsistency in reflected shock wave speed and pressure; 3) differences between the flows resulting from the reflection of shock waves and detonation waves. Additional topics include the interaction of detonations with the surfaces of liquid layers within the piping system; and the response of piping to deflagration-to-detonation transition.

Wednesday, November 13, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.

Biomixing: When Organisms Stir Their Environment

Jean-Luc Thiffeault

University of Wisconsin
Madison, WI

As fish, micro-organisms, or other bodies move through a fluid, they stir their surroundings. This can be beneficial to some fish, since the plankton they eat depends on a well-stirred medium to feed on nutrients. Bacterial colonies also stir their environment, and this is even more crucial for them since at small scales there is no turbulence to help mixing. It has even been suggested that the total biomass in the ocean makes a significant contribution to large-scale vertical transport, but this is still a contentious issue. We propose a simple model of the stirring action of moving bodies through both inviscid and viscous fluids. An attempt will be made to explain existing data on the displacements of small particles, which exhibits probability densities with exponential tails. A large-deviation approach helps to explain some of the data, but mysteries remain. This is joint work with Steve Childress, George Lin, and Peter Mueller.

Wednesday, November 20, 2013
3:30 PM
Seaver Science Library, Room 150 (SSL 150)

Refreshments will be served at 3:15 pm.