MEAM Seminar Series Fall 2011

Seminars are held on Tuesday mornings, with coffee at 10:30 am in the Levine Hall Mezzanine and the seminar beginning at 10:45 am in Wu and Chen Auditorium (unless otherwise noted).

To be added to the MEAM Events mailing list (which sends notifications regarding all departmental seminars and events) please email us at meam-events@lists.seas.upenn.edu.


September 13

Gregory S. Chirikjian, Professor of Mechanical Engineering, Johns Hopkins University
"Stochastic Models in Robotics and Structural Biology "

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Abstract: Many stochastic problems of interest in engineering and biology involve random rigid-body motions. These include the statistical mechanics of DNA and other biopolymers, mobile robot path planning, and robot-arm kinematics. These topics will be reviewed and will lead to a discussion of our current work on multi-robot team-diagnosis and repair, information fusion, and self-replicating robots. In order to quantify the robustness of such robots, measures of the degree of environmental uncertainty that they can handle need to be computed. The entropy of the set of all possible arrangements (or configurations) of spare parts in the environment is such a measure, and has led us to study problems at the foundations of statistical mechanics and information theory, which we have in turn brought back to model problems in structural biology, including the modeling of Brownian-motion-induced motions of end-constrained DNA. Our work on class averaging methods in electron microscopy will also be discussed as time permits.

Speaker Biography: Gregory S. Chirikjian received undergraduate degrees from Johns Hopkins University in 1988, and the Ph.D. degree from the California Institute of Technology, Pasadena, in 1992. Since 1992, he has been on the faculty of the Department of Mechanical Engineering, Johns Hopkins University, where he has been a full professor since 2001. From 2004-2007 he served as department chair. His research interests include robotics, applications of group theory in a variety of engineering disciplines, and the mechanics of biological macromolecules. He is a 1993 National Science Foundation Young Investigator, a 1994 Presidential Faculty Fellow, and a 1996 recipient of the ASME Pi Tau Sigma Gold Medal. In 2008 he became a Fellow of the ASME, and in 2010 he became a Fellow of the IEEE. He is the author of more than 180 journal and conference papers and primary author on two books: Engineering Applications of Noncommutative Harmonic Analysis (2001) and Stochastic Models, Information Theory, and Lie Groups, Vol. 1. (2009).

September 20

Robert E. Ecke, Director, Center for Nonlinear Studies, Los Alamos National Laboratory
Energy Futures: From carbon sequestration to the smart grid of tomorrow

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The challenges of maintaining energy supply, harnessing intermittent renewable energy resources,
and mitigating the effects of carbon dioxide emissions on global climate are daunting.  At the same
time, problems at the intersection of energy and climate offer great opportunities for the application
of science and technology for the benefit of society.  I will discuss two problems in this general area:
an experimental study of mass transport efficiency in porous media to gauge the potential effectiveness
of sequestering carbon dioxide in porous media aquifers. We use several laboratory analogs to evaluate
the fundamental mass transfer efficiency of gravitationally unstable fluid layers.  The first experiment
consists of a layer of water over a layer of propylene glycol confined to a Hele-Shaw cell (closely
spaced vertical walls).  The second is the same fluids in a cylindrical 3D geometry. In the second
part of my talk, I will present an overview of the types of problems one is faced with in modifying
the existing power grid to incorporate renewable energy sources such as wind and solar power.  This
class of problems relies on optimization and control approaches that help address the issues caused
by the intermittent nature of renewable energy.

September 27 - JOINT CBE/MEAM Seminar

John J. McGrath

Division Director - Chemical, Bioengineering, Environmental and Transport Systems Directorate for Engineering, National Science Foundation

"Overview of NSF, the Engineering Directorate & the CBET Division"

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The goals of this presentation are to provide the audience with useful information about NSF and for the speaker to learn more about University of Pennsylvania engineering faculty perspectives of NSF. Priorities, budget information and funding opportunities that span from the CBET division level, up through the Engineering Directorate and across NSF will be described. Budget information for FY2011 and FY2012 will be described. The speaker will offer a view of “What’s Happening Now at NSF” as well as a glimpse of emerging issues. This, along with sharing some thoughts on challenges NSF is facing should provide background for an interesting discussion.

 

October 7 - SPECIAL MEAM Seminar

Gal deBotton, Department of Mechanical Engineering, Ben-Gurion University, Israel

"Electroactive polymer composites - Mechanical response, stability, wave propagation and Band-gaps"

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Gal  deBotton, Gal Shmuel and Stephan Rudykh
Department of Mechanical Engineering, Ben-Gurion University, Beer-Sheva, 84105 Israel

The work deals with the electromechanical response of nonlinearly coupled heterogeneous materials capable of large deformations. The characterization of the deformation of heterogeneous dielectrics due to electrostatic excitation is initially considered. Within the framework of infinitesimal elasticity it is shown that the coupled governing equations at the macroscopic level are identical to the ones at the microscopic level. Application of the results to the class of laminates demonstrates that the electromechanical coupling can be intensified by orders of magnitude. To examine the coupled behavior of composites in finite deformation a finite element code is adapted together with electrostatic and mechanical periodic boundary conditions. In addition, we find that heterogeneity is an origin for instability development. This issue is tackled by superimposing infinitesimal perturbations on the pre-stretched composite. A general criterion for the instability onset is introduced and implemented to a class of anisotropic materials. The significant influence of the microstructure on the stability of the composite is demonstrated. In parallel, we also analyze the propagation of waves in electrically pre-stretched laminates. The dispersion relation, relating between the perturbation frequencies and the wave lengths, is determined by making use of Bloch-Floquet theorem. Band-gaps, which are ranges of frequencies at which waves cannot propagate, are identified.

Some of the results were developed in collaboration with Kaushik Bhattacharya (CALTECH, CA), Massimiliano Gei (University of Trento, Italy) and Gil Uner (Ben-Gurion University, Israel).

October 18

Kaushik Dayal, Assistant Professor of Mechanics, Materials and Computing, Department of Civil and Environmental Engineering, Carnegie Mellon University
"Multiscale methods for Complex Crystals and Nano-/Bio-structures"

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I will talk about two related approaches to develop multiscale atomistic methods for complex materials. First, I will discuss defects in electronic materials such as solid oxides and ferroelectrics. These materials have long-range electrostatic interactions between charges, as well as electric fieldsthat exist over all space outside the specimen. I will describe a multiscale methodology aimed at accurately and efficiently modeling defects in such materials in complex geometries. Our approach is based on a combination of Dirichlet-to-Neumann maps to consistently transform the problem from all-space to a finite domain; the quasicontinuum method to deal with short-range atomic interactions, and rigorous thermodynamic limits of dipole lattices from the literature. We apply the method to understand the electromechanics of a ferroelectric under complexelectrical loading.

Second, I will describe our use of the “Objective Structures” approach to modeling nano-/bio- structures. This approach exploits symmetry-based analogies between crystals and nano-/bio- structures to extend methods developed for crystalline materials. I will describe the use of this idea to non-equilibrium molecular dynamics and equilibrium normal mode analysis of carbon nanotubes, and interpret the results in the framework of continuum thermomechanics. I will also outline preliminary work on applying the framework to the multiscale modeling of lipid membranes.

The research is joint work with PhD students Amin Aghaei and Jason Marshall, whose work received the 2011 USNCCM Best Poster Award for "Multiscale Mechanics with Long-Range Electrostatic Interactions."

Kaushik Dayal Biography

Kaushik Dayal is an Assistant Professor at Carnegie Mellon University in the Mechanics, Materials, and Computing Group of the Department of Civil and Environmental Engineering. He received his B. Tech. at the Indian Institute of Technology Madras in 2000, and his M.S. in Aeronautics and Ph.D. in Mechanical Engineering at the California Institute of Technology in 2007. He spent a year as a Postdoctoral Researcher at the University of Minnesota in the Department of Aerospace Engineering and Mechanics, supported by a Supercomputing Institute Research Scholarship, and moved to Carnegie Mellon in 2008. His research interests are in the area of multiscale methods, particularly with electromagnetic forces and in settings that are away from equilibrium. His work on ferroelectrics was recognized by the Acta Materialia Student Paper Award for 2008.

October 25

Paris R. von Lockette, Associate Professor, Rowan University
"Investigating symmetry classes in magneto-rheological elastomers (MREs)"

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Traditionally, magnetorheological elastomers (MREs) are comprised of soft-magnetic particles in a rubbery matrix. Technologically, the underlying magnetization and spatial alignment of the embedded magnetic particles drives their observed changes in stiffness under a magnetic field (the so called MRE effect). Researchers, focusing on the MRE effect, have developed various active vibration control devices using the material. Other researchers have worked to improve the MRE effect, optimizing particle fractions and particle alignments, while still others have sought to model MRE behavior. Past work, however, has focused almost exclusively on the use of soft-magnetic filler particles ignoring the possible use of hard-magnetic fillers. These hard-magnetic MREs yield little MRE effect but may be used as “free” actuators whereas soft-magnetic MREs may not. The difference in behavior is best understood by examining the role of particle alignment and magnetization symmetries on MRE behavior. Enhanced understanding of the underlying physics will in turn lead to the next generation of MRE materials and devices.

This work defines and examines four classes of MREs based upon permutations of  particle alignment and magnetization symmetries. Particle alignments may be either Isotropic (disordered) or Anisotropic (ordered). Particle magnetizations may also be either Isotropic (soft-magnetic) or Anisotropic (hard-magnetic) which yields A-A, A-I, I-A, and I-I classifications. Traditional MREs comprise only the I-I and A-I classes.  Dynamic shear and static bending experiments differentiate magnetorheological response and actuation capabilities across all for classes.  Class A-A materials are shown to perform best as actuators but poorly as dynamic stiffness elements while I-I and A-I classes perform best as dynamic stiffness elements but are incapable of “free” actuation.  Energy-based and phenomenological analytical models yield predictive equations and quantitative measures of those rheological differences. Results of finite element modeling reinforce the importance of class delineations and highlight the role of magnetization anisotropy in the actuation response across the four material classes.

November 1

Noel Perkins, Donald T. Greenwood Collegiate Professor, Arthur F. Thurnau Professor, Department of Mechanical Engineering, University of Michigan


"Wireless Technology for Analyzing Human Motion and Athletic Skill"

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The combining of MEMS inertial sensors (angular rate gyros and accelerometers) with RF transceivers makes possible the design of miniature, wireless inertial measurement units (IMU’s). When embedded in sports equipment, wireless IMU’s enable one to deduce the three-dimensional, rigid body dynamics of that equipment. For instance, a miniature IMU attached to the knob of a baseball bat yields a highly portable and non-invasive means to measure and analyze the dynamics of the swing.  In this seminar, we will review novel sports training systems that are being developed and commercialized for sports including baseball, basketball, bowling, golf, fly fishing, among others.  An overview will be provided of the wireless IMU hardware and the measurement theory for deducing rigid body motions. How these are used to analyze athletic skill will be highlighted in several examples. We will close by describing other human motion studies that employ this technology for surgeon training, gait analysis, tele-rehabilitation, and the analysis of balance disorders.

 

miniaturizedIMU(transmitterside)

   

Dr. Noel Perkins is presently the Donald T. Greenwood Collegiate Professor of Mechanical Engineering and an Arthur F. Thurnau Professor at the University of Michigan. His research interests include computational and nonlinear dynamics, MEMS inertial sensor applications for human motion, the mechanics of single molecule DNA, and engineering structural dynamics. He serves as the Editor of the ASME Journal of Vibration and Acoustics, is a Fellow of the American Society of Mechanical Engineers, and a recipient of the ASME N. O. Myklestad Award, the General Motors Outstanding Distance Learning Faculty Award, and the Academic Challenge Award from the Technical University of Munich. He remains active in commercialization activities for MEMS-based sports training systems, and is a founding partner of Cast Analysis, LLC that manufactures a fly casting training system for the fly fishing industry.

November 8

Seungmoon Choi, Associate Professor of Computer Science and Engineering and Director, Haptics and Virtual Reality Laboratory, Pohang University of Science and Technology (POSTECH), Korea;

Visiting Associate Professor, Dept of Mechanical Engineering & Applied Mechanics, University of Pennsylvania
"Haptic Augmented Reality – Concept and Research Progress"

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Abstract:
This talk presents the concept and research status of haptic augmented reality. Haptic augmented reality refers to the technology or applications wherein a user in a real environment interacts with real objects with the aid of a haptic interface, while experiencing augmented haptic feels of the real objects. For instance, a virtual apple can be rendered on top of a real desk both visually and haptically, or a virtual tumor can be created inside a real breast in order to practice breast tumor palpation and detection. This exciting new technology allows us to augment real haptic sensations by delivering purely virtual haptic sensations inside a real environment or mixing virtual stimuli with real stimuli, just like changing the color of a real object with the visual augmented reality technology. In addition, other research topics on-going in the speaker’s laboratory at POSTECH are also briefly introduced, including human motor skill modeling and transfer and tactile perception and rendering for mobile devices.

Biography:
Seungmoon Choi received the BS and MS degrees in control and instrumentation engineering from Seoul National University in 1995 and 1997, respectively, and the PhD degree in electrical and computer engineering from Purdue University in 2003. He worked as a post-doctoral research associate at Purdue University in 2004-2005. At present, he is an associate professor of computer science and engineering at Pohang University of Science and Technology (POSTECH). He received an Early Career Award 2011 from IEEE Technical Committee on Haptics and several best paper awards from premium international conferences including IEEE Haptics Symposium and IEEE World Haptics Conference. He is a co-chair of IEEE Technical Committee on Haptics, an associate editor of IEEE Transactions on Haptics, and an editorial board member of Virtual Reality. He has also served in the program committee of a number of international conferences on haptics. His research interests lie on haptic rendering and perception, emphasizing on kinesthetic rendering of hardness and texture, tactile rendering, sensorimotor skill modeling and transfer, haptic augmented reality, mobile haptic interface, data haptization, and applied perception. His basic research has been applied to mobile devices, automobiles, virtual prototyping, and motion-based remote controllers.

November 15

No Seminar today

November 22

Julio M. Fernandez, Professor of Biological Sciences, Columbia University
" Mechanical Biochemistry"

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Abstract: The statement that “everything in biology is mechanical” is an obvious exaggeration, but not by much.  Indeed, mechanical forces are the most common perturbation encountered by proteins in vivo.  However, most of our current understanding of protein dynamics comes from bulk chemical or thermal denaturation studies that became standard over the past 50 years.  Unfortunately those studies cannot be used to understand the dynamics of proteins under force.  Fundamentally new approaches are needed.  I will discuss in my lecture the growing use of single molecule force-clamp spectroscopy to study the folding, unfolding and chemical dynamics of proteins placed under force.  In particular I will discuss the use of force spectroscopy to study the dynamics of thiol/disulfide exchange reactions as they occur during oxidative protein folding in the endoplasmic reticulum.  I will describe the use of these novel techniques to study the activity of enzymes such as thioredoxin, protein disulfide isomerase (PDI) and glutaredoxin.  The long-term aim of my studies is to develop a force-spectroscopy approach to study biochemistry, which will provide vital new information on how proteins function in-vivo.

1.- Fernandez, J.M. and Li, H. B. Force-clamp spectroscopy monitors the folding trajectory of a single protein (2004), Science, 303: 1674-1678.

2.- Wiita et al, Probing the chemistry of thioredoxin catalysis with force (2007), Nature, 450:124-7.

3.-Alegre-Cebollada et al, Direct observation of disulfide isomerization in a single protein (2011) Nature Chemistry, 3: 882-887.

Bio: I lead an interdisciplinary group of physicists, chemists and biologists that includes Ph.D. and MD/Ph.D. students and graduates. I have developed techniques to study the effect of a mechanical force on the activity and conformation of proteins. My studies are done at the single protein level. I use these techniques to examine two fundamental biological processes: protein folding and enzyme catalysis. My most recent work uncovered that chemical reactions catalyzed by an enzyme are sensitive to mechanical forces applied to their substrate. We have shown this for thioredoxin and PDI, enzymes that are thought to play important roles in HIV infection and heart disease.

Professional experience: Chairman, Department of Physiology and Biophysics, Mayo Clinic. Chairman, Biophysical Chemistry study section at NIH. Awards: Alexander von Humboldt Senior US scientist award, Biophysical Society US Genomics Award in the field of Single Molecule Biology. 

November 29

Andrea Liu, Professor of Physics, University of Pennsylvania
"Vibrations and Flow defects in Jammed Packings"

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Like liquids, solids can flow under applied shear stresses. Crystalline solids flow via rare rearrangements controlled by a population of lattice defects, namely, dislocations. In disordered solids, rearrangements tend to be localized, but there is no obvious way to identify defects that might control them. Can these rare localized rearrangements occur anywhere, as in a liquid, or do glasses possess a population of ‘‘soft spots,’’ analogous to dislocations in crystalline solids, which are structurally distinct and susceptible to rearrangement?  We have used the low-frequency normal modes of vibration to identify a population of soft spots in a model glass. We find that, as with dislocations in crystals, rearrangements begin at soft spots, that the population of soft spots evolves slowly compared to the time between rearrangements, and that there are structural differences between soft spots and the rest of the system.  Thus, soft spots are good candidates for elementary defects that control the flow of disordered solids.

December 6

Celia Reina Romo, Lawrence Fellow, Lawrence Livermore National Laboratory
"Modeling and simulation of damage by nucleation and void growth: a multiscale approach"

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Abstract: Voids are observed to be generated under sufficient loading in many materials, ranging from polymers and metals to biological tissues. Experiments indicate that the voids drastically influence the overall macroscopic response while at the same time, the evolution of these cavities is dependent on the complete deformation history of the material. Tools capable of reproducing the experimental observations are therefore very desirable. 
The work to be presented is concerned with both, the appearance of voids (nucleation process) and the modeling and simulation of materials in the presence of these voids (growth process). The nucleation phenomenon is very material specific and we will therefore restrict our attention to the feasibility of a specific nucleation mechanism in metals subjected to shock-loading conditions. Such mechanism is based on the diffusion of vacancies and their cluster coarsening till the formation of sufficiently large voids for further growth by plastic deformation. The model developed is of multiscale character and allows the computation of the nucleation times as a function of temperature and volumetric deformation. The limits of applicability of the model are discussed and the obtained results are compared to experimental data of spall setting its range of validity. Concerning the void growth process, a variational two-scale continuum model will be presented that is applicable to general materials under arbitrary loading conditions. Specifically, a representative volume element consisting of a hollow sphere is used to describe the microscopic fields and an equivalent homogeneous material is used for the macroscopic behavior. A Ritz-Galerkin method based on spherical harmonics, specialized quadrature rules and exact boundary conditions is employed to discretize individual voids at the microscale. This discretization results in very few degrees of freedom, material-frame indifference and it exactly preserves all material symmetries. The resulting multiscale model is verified extensively and its applicability is shown through several material point calculations and a full two-scale finite element implementation.

Bio: Celia Reina is a Lawrence Postdoctoral Fellow at the Lawrence Livermore National Laboratory. She received her Bachelor's degree in Mechanical Engineering from the University of Seville (Spain) and a Master in Structural Dynamics at Ecole Centrale Paris (France), both in 2006. She then moved to Caltech where she pursued her Master's and Doctoral degree in Aeronautics under the supervision of Pr. Michael Ortiz.  After the completion of her PhD in 2010 she joined the Livermore Laboratory as a postdoc, which she combined with a six-month stay in Bonn (Germany) at the Hausdorff Center for Mathematics working with Pr. Sergio Conti. Celia Reina is the recipient of the William F. Ballhaus Prize for an outstanding doctoral dissertation in Aeronautics at Caltech, the Rolf D. Bühler Memorial Award in Aeronautics for outstanding academic achievement in the Master of Aeronautics at Caltech and the First National Award for the best academic records within the degree of Industrial Engineering in Spain.

December 20

Changchun Liu, Research Associate, Department of Mechanical Engineering, University of Pennsylvania

"Point of Care Diagnostic Devices for Pathogen Detection"

Due to final exams, this seminar will be held in Towne 337

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There is a critical need for rapid and accurate point-of-care diagnostic devices for detecting pathogens, particularly in resource-limited settings. This talk will discuss four microfluidic cassettes for detecting pathogens at the point of care.  In the first part of the talk, I will discuss a self-contained, integrated, disposable, sample-to-answer, pouch-based immunoassay cassette for HIV antibody detection in oral fluids. The cassette stores on-board all required buffers.  On-chip pumping and flow control are provided with a spring-loaded, timer actuator and the sequence of operations is mechanically programmed. In the second part of the talk, I will describe a simple, point of care, inexpensive, single-chamber cassette for the detection of nucleic acids extracted from HIV virus in oral fluids. The cassette utilizes a single reaction chamber for extraction and isothermal amplification of nucleic acids. The chamber is equipped with an integrated, flow-through, cellulose membrane for the isolation, concentration, and purification of DNA and/or RNA. The nucleic acids captured by the membrane are used directly as templates for amplification without a need for elution, thus simplifying the cassette’s flow control. The device provides performance comparable to that of state of the art benchtop equipment. In the third part of the talk, I will discuss a low-cost, non-instrumented, water-activated, self-heating cassette that does not require electric power to operate. The isothermal amplification reaction is activated by adding water to the exothermic reaction chamber, and the test results can be observed by naked eye within one hour without any need for any instrument. The performance of the device was evaluated by detecting E. Coli DNA. In the last part of the talk, I will present a mosquito-in-a-chip device that can perform rapid nucleic acid-based identification of malaria-transmitting vectors. The test results can be observed visually and, if desired, recorded and transmitted with a cell phone camera.