MEAM Seminar Series Fall 2015
For Summer 2015 Seminars, click here.
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).
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September 1: Special Seminar
Jaydev Desai, Professor, Department of Mechanical Engineering, University of Maryland at College Park
"Flexible Meso-scale Robotic Systems for Image-Guided Neurosurgery"
This talk will focus specifically on two areas within image-guided robot-assisted neurosurgery, namely: a) MINIR: Minimally Invasive Neurosurgical Intracranial Robot and b) Neurosurgical Intracerebral Hemorrhage Evacuation (NICHE) robot.
Brain tumors are among the most feared complications of cancer occurring in 20–40% of adult cancer patients. Though there have been significant advances in treatment, the prognosis of these patients is poor. Whether there is a primary malignancy or a secondary malignancy, whenever the brain of the cancer patient is involved in treatment, there is a significant impact on their overall quality of life. While the most optimal treatment currently for most brain tumors involves primary surgical resection, many patients may not be able to undergo that treatment plan due to either their poor general health or an unfavorable location (either deep inside the brain or inaccessibility of the tumor) of the lesion. Hence, this is a significant healthcare problem. Similarly, spontaneous intracerebral hemorrhage (ICH) occurs in about 2 million people worldwide. The 30-day mortality rate is about 32-50% and functional independence after 6 months is achieved in only about 20-25% of the individuals who survive such hemorrhages. Removal of the blood clot and decreasing the recurrence of re-hemorrhage using robotic techniques could potentially help with effective management of ICH. In both cases, traditional approaches are limiting, since they do not provide visualization beyond the direct line-of-sight.
This talk will focus on our progress on the development of flexible meso-scale image-guided robotic systems for these two National Institutes of Health (NIH) funded projects involving innovative design of the robots and the associated kinematics, magnetic resonance imaging (MRI) compatible actuation, adaptive backbone stiffening of the flexible robot, and evaluation of these systems under the appropriate imaging environment.
Dr. Jaydev P. Desai is currently a Professor in the Department of Mechanical Engineering and a Member of the Maryland Robotics Center at the University of Maryland, College Park (UMCP). He completed his undergraduate studies from the Indian Institute of Technology, Bombay, India, in 1993. He received his M.A. in Mathematics in 1997, and M.S. and Ph.D. in Mechanical Engineering and Applied Mechanics in 1995 and 1998 respectively, all from the University of Pennsylvania. He was also a Post-Doctoral Fellow in the Division of Engineering and Applied Sciences at Harvard University. He is a recipient of several NIH R01 grants, NSF CAREER award, and was also the lead inventor on the “Outstanding Invention of 2007 in Physical Science Category” at UMCP. He is also the recipient of the Ralph R. Teetor Educational Award. He has been invited to give a talk at the National Academy of Sciences “Distinctive Voices” seminar series on the topic of “Robot-Assisted Neurosurgery” and also attend the National Academy of Engineering’s U.S. Frontiers of Engineering Symposium. He has over 150 publications, is the founding Editor-in-Chief of the Journal of Medical Robotics Research, and Editor-in-Chief of the Encyclopedia of Medical Robotics (currently in preparation). His research interests are primarily in the area of image-guided surgical robotics, rehabilitation robotics, grasping, and cancer diagnosis at the micro-scale. He is a Fellow of the ASME and a Senior Member of the IEEE.
Rebecca Pierce, PhD Candidate, University of Pennsylvania
Advisor: Katherine Kuchenbecker
2:00 pm, Levine 307
"Increasing Transparency and Presence in Teleoperation Through Human-Centered Design"
Teleoperation allows a human to control a robot to perform dexterous tasks in remote, dangerous, or unreachable environments. A perfect teleoperation system would enable the operator to complete such tasks at least as easily as if he or she was to complete them by hand. This ideal teleoperator must be perceptually transparent, meaning that the interface appears to be nearly nonexistent to the operator, allowing him or her to focus solely on the task environment, rather than on the teleoperation system itself. Furthermore, the ideal teleoperation system must give the operator a high sense of presence, meaning that the operator feels as though he or she is physically immersed in the remote task environment. This dissertation seeks to improve the transparency and presence of robot-arm-based teleoperation systems through a human-centered design approach, specifically by leveraging scientific knowledge about the human motor and sensory systems.
First, this dissertation aims to improve the efferent teleoperation control channel, which carries information from the human operator to the robot. The traditional method of calculating the desired position of the robot's hand simply scales the measured position of the human's hand. This commonly used motion mapping erroneously assumes that the human's produced motion identically matches his or her intended movement. Given that humans make systematic directional errors when moving the hand under conditions similar to those imposed by teleoperation, we propose a new paradigm for determining data-driven human-robot motion mappings for teleoperation: the human operator mimics the target robot as it autonomously moves its arm through a variety of trajectories in the horizontal plane. Three data-driven motion mapping models are described and evaluated for their ability to correct for the systematic motion errors made in the mimicking task. Individually-fit and population-fit versions of the most promising motion mapping model are then tested in a teleoperation system that allows the operator to control a virtual robot. Results of a user study involving nine subjects indicate that the newly developed motion mapping model significantly increases the usability of the teleoperation system.
Second, this dissertation seeks to improve the afferent teleoperation control channel, which carries information from the robot to the human operator. We aim to increase the presence experienced in a teleoperation system by providing the operator with multiple novel modalities of haptic (touch-based) feedback. We describe the design and control of a wearable haptic device that provides kinesthetic grip-force feedback through a geared DC motor and tactile fingertip-contact-and-pressure and high-frequency acceleration feedback through a pair of voice-coil actuators mounted at the tips of the thumb and index finger. Each included haptic feedback modality is known to be fundamental to direct task completion and can be implemented without great cost or complexity. A user study involving thirty subjects investigated how these three modalities of haptic feedback affect an operator's ability to control a real remote robot in a teleoperated pick-and-place task. This study's results strongly support the utility of grip-force and high-frequency acceleration feedback in teleoperation systems and show more mixed effects of fingertip-contact-and-pressure feedback.
Ron Schoff, Technology Innovation Program, Electric Power Research Institute
"Power System Transformation in an Era of Increasing Distributed Generation, Dynamic Power Delivery, and Interactive Use of Electricity"
The electric power industry is changing at a pace that is unprecedented in its history. The inherently intermittent nature of variable generation (wind and solar), which is growing at a faster rate than any other form of generation, poses challenges for reliable power system operation. Consumers in large numbers are installing photovoltaic panels, as well as purchasing plug-in electric vehicles, smart appliances, and equipment that enables them to better manage their electricity use. Recent severe weather events, a high-profile physical attack on a west coast substation, and other high-impact, low-frequency events are forcing utilities to enhance their resiliency. The Internet of Things and predicted explosive propagation of connectivity across consumer devices and power system devices will also drive change, while helping to address some of these challenges. EPRI’s R&D portfolio is evolving to enable and support the needed revolutionary power system transformation that must take place to address these challenges. This seminar will summarize changes in the power system and EPRI’s plan for working closely with stakeholders to develop innovative solutions to develop an Integrated Grid.
Ronald Schoff is the manager of the Technology Innovation (TI) program at the Electric Power Research Institute (EPRI).
His responsibilities include managing the five core components of the TI Program: Thought Leadership, Innovation Scouting, Strategic Programs, Breakthrough Technologies and the Polaris Initiative. The program’s cross-cutting research, development and demonstration (RD&D) projects portfolio scouts, influences, and builds on early-stage work across the global science and technology communities to capture innovations for application-oriented development and demonstration by EPRI.
Before joining TI, Schoff worked in EPRI’s CoalFleet for Tomorrow™ program, managing evaluations of advanced power generation technologies, including coal gasification combined-cycle (IGCC), ultrasupercritical pulverized coal (USCPC), natural gas-fired combined cycles (NGCC), and power cycles incorporating carbon dioxide capture and sequestration (CCS). In addition, Schoff has been active in developing long-range technology roadmaps.
Prior to joining EPRI, Schoff worked as an engineer for Parsons Corporation’s Research and Development Group in Pittsburgh, where he focused on thermodynamic power plant performance and capital cost estimation of advanced fossil power plants and a variety of other conventional and novel processes.
Schoff holds a Bachelor of Science degree in chemical engineering from the University of Pittsburgh and a Master of Science degree in chemical engineering from Villanova University. He is a senior member of the American Institute of Chemical Engineers and a registered engineer-in-training. He has published numerous papers and given talks at various technical conferences worldwide.
David L. Goldsby, Associate Professor, Department of Earth and Environmental Science,
University of Pennsylvania
"Experimental Constraints on the Flow of Ice: Evidence from Greenland and Ganymede"
Abstract: The mechanical and rheological behavior of ice is important for understanding and predicting the behavior of glaciers, ice sheets, and icy planetary bodies. The rheology of glaciers and ice sheets is canonically described using the empirical Glen law, a power law between strain rate and stress with a value of the stress exponent (n) of 3, attributed to dislocation creep. Here I demonstrate that the classic Glen law represents the transition between two creep mechanisms, dislocation creep proper (n=4) and ‘superplastic flow’ (n=2), the latter a mechanism wherein dislocation slip is accommodated by grain boundary sliding (GBS). The GBS creep mechanism, which is markedly dependent upon grain size, is revealed by creep experiments on ice specimens of small (sub-200 m) grain size. Scaling the flow law for GBS creep to the larger grain sizes characteristic of glaciers and ice sheets, and comparing it against creep data from glacier field studies, indicates that this mechanism dominates their flow at all but the highest stresses (~0.1 MPa), at which a transition occurs to dislocation creep. Thus, modeling flow of glaciers, ice sheets and icy moons over the full range of relevant stresses requires a composite flow law containing parallel contributions of GBS creep and dislocation creep. Implications of this new description of ice flow - for terrestrial glaciers and ice sheets; for the composition of Mars’ South Polar Ice Cap; for the existence of an internal ocean on Europa; and for crater retention ages and the origins of grooved terrain on Ganymede - will be presented.
Bio: David Goldsby is an Associate Professor in the Department of Earth and Environmental Sciences at the University of Pennsylvania. He is an ‘experimental geophysicist’ with research interests in materials science, tribology, rock mechanics, glaciology and earthquake mechanics, with an emphasis on the rheological behavior of planetary materials. Dr. Goldsby applies experimental methods and theories from materials science to understand deformation mechanisms in Earth materials that control large-scale geophysical phenomena, such as the nucleation of earthquakes and the motion of Earth’s great ice sheets. Examples of this ‘Earth materials science’ approach include hot isostatic pressing of fine-grained samples to explore creep mechanisms involving grain boundary sliding, and atomic force microscopy and nanoindentation to explore the frictional behavior of Earth materials at atomic to microscopic scales. Deformation experiments at ambient and elevated confining pressures, at high temperatures in the case of mantle minerals like olivine and cryogenic temperatures in the case of ice and other cryomaterials, are conducted in the Experimental Geophysics Lab at Penn. One focus of Dr. Goldsby’s research is ‘superplastic flow’ of materials, a creep behavior involving grain boundary sliding. This flow behavior dominates the creep rate of a material at lower stresses than does dislocation creep, and can therefore control the rheological behavior of materials in low-deviatoric-stress natural settings, such as within glaciers, ice sheets and icy moons, as well as in the interiors of Earth and other planets.
Dr. Goldsby completed his PhD in Geophysics at the University of Minnesota in 1997, and was an Associate Professor (Research) at Brown University until 2014. He is a longtime member of the American Geophysical Union and the Southern California Earthquake Center, and Facilities Chair of the new rock mechanics consortium DEFORM (Deformation Experimentalists at the Frontier Of Rock and Mineral Research).
Piotr Marszalek, Professor, Department of Mechanical Engineering and Materials Science, Duke University
"The Nanomechanics of Polysaccharides, Nucleic Acids, and Proteins Beyond the Entropic Elasticity Regime"
Compared to other single-molecule techniques, AFM uses rather stiff force transducers (cantilevers) and therefore it may apply small and large stretching forces to molecules. Thus, AFM is uniquely capable to determine a molecule’s high energy conformations that cannot be examined by other techniques such as X-ray crystallography or NMR. In my talk, I will present our AFM studies, supported by computer simulations that are aimed at unraveling the fundamental relationships between structural and mechanical properties of individual polysaccharides, proteins, and DNA. AFM stretching measurements on polysaccharides reveal that their elasticity frequently deviates from the simple entropic elasticity of other polymers and that it is governed by force-induced conformational transitions within the sugar rings (such as forced chair-boat transitions) and within the polysaccharide backbone. Our DNA force spectroscopy measurements and simulations are aimed at unraveling the fundamental relationships between the canonical structures of single- and double-stranded DNA and the mechanisms of their molecular elasticity that critically affects its biology. AFM measurements of mechanical unfolding and refolding reactions of repeat and large multi-domain proteins under vectorial conditions, similar to those experienced by the nascent polypeptide chain, can contribute to elucidating the mechanism of co-translational protein folding in vivo.
Piotr E. Marszalek is a Professor of Mechanical Engineering and Materials Science from Duke University. His research focuses on investigating relationships between structural and mechanical properties of biopolymers (polysaccharides, DNA, proteins), which he studies at the single-molecule level. His main approaches are experimental scanning probe microscopy techniques and computational methods involving Molecular Dynamics simulations and ab initio quantum mechanical calculations. The ultimate goal of this research is to understand the above-mentioned relationships at an atomic level and to apply the knowledge gained towards elucidating basic phenomena such as: molecular recognition that mediates interactions between proteins and sugars, mechanotransduction that underlies mechanical sensing and hearing in all organisms, and protein folding that is fundamental to all biology. His DNA research is aimed at exploiting atomic force microscopy techniques to develop new ultra-sensitive assays for detecting and examining DNA damage, the process underlying carcinogenesis, and to increase our mechanistic understanding of DNA damage and repair processes. This research, in addition to its basic science aspects, will lay a foundation for the future use of AFM technologies in the nanoscale DNA diagnostics with a potential to directly benefit human health.
Dr. Marszalek received his PhD in Electrical Engineering in 1991 from the Electrotechnical Institute in Warsaw, Poland. From 1998 to 2002 he served as an Assistant Professor of Biophysics at the Mayo Clinic. From 2002 to 2009 he was an Associate Professor of Mechanical Engineering at Duke University, becoming full Professor in 2009.
Guruswami Ravichandran, John E. Goode, Jr., Professor of Aerospace and Professor of Mechanical Engineering; Director, Graduate Aerospace Laboratories, California Institute of Technology
"Adhesion: Elasticity, Heterogeneity, and Peeling"
Peeling is a ubiquitous process, which is important to many applications in engineering and biology. The peeling of homogeneous elastic tape from a rigid substrate has been studied widely. While there is a good understanding of the homogenized behavior of heterogeneous materials concerning properties such as the overall elastic moduli that are characterized by a variational principle, much remains unknown concerning those properties that are characterized by evolutionary processes such as fracture. This talk will discuss the process of peeling a heterogeneous adhesive tape from a rigid substrate as a case study to demonstrate the complexities that can arise in this situation. Specifically, it is shown through experimentation and theoretical analysis that one can dramatically enhance the overall adhesive strength by patterning the elastic modulus of the tape. It is also shown that by patterning the adhesive, asymmetry can be induced where the force needed to peel the membrane depends not only on the direction but also the sense of the peel. Remarkably, these modifications in peeling strength come from variations in the energy associated with bending of the tape near the peeling front which is negligible compared to the overall energy in the system. This illustrates that in evolutionary processes, perturbations with apparently negligible energy can have an anomalously large macroscopic effect. The talk will conclude with broader lessons for other phenomena including fracture, dislocations, phase boundaries and wetting fronts.
Guruswami (Ravi) Ravichandran is John E. Goode, Jr. Professor of Aerospace and Professor of Mechanical Engineering and Director of the Graduate Aerospace Laboratories (GALCIT) at the California Institute of Technology. He received his B.E. (Honors) in Mechanical Engineering from University of Madras, Sc.M. in Engineering and Applied Mathematics, and Ph.D. in Solid Mechanics and Structures from Brown University. He is a member of the National Academy of Engineering, European Academy of Sciences and Arts, and International Academy of Engineering. He is a Fellow of the American Society of Mechanical Engineers, Society for Experimental Mechanics and American Academy of Mechanics (AAM). He was named Chevalier de l'ordre des Palmes Academiques by the Republic of France. His awards include A.C. Eringen Medal from SES, Warner T. Koiter Medal from ASME and William M. Murray Lecture Award from SEM. His research interests are in mechanics of materials, dynamic deformation, damage and failure, active materials, biomaterials and experimental methods.
Jamal Yagoobi, George I. Alden Professor and Department Head, Department of Mechanical Engineering, Worcester Polytechnic Institute
"Electrohydrodynamically Driven Two-Phase Heat Transport Devices for Space and Ground Applications"
Abstract: Electrohydrodynamic (EHD) conduction pumping of a dielectric liquid arises from the interaction of the induced electric fields and flow fields via the Coulomb force. The required free charges come from the dissociation and recombination of neutral electrolytes present in the fluid. When the external electric field exceeds a threshold, the rate of dissociation exceeds that of recombination. There is a non-equilibrium heterocharge layer that forms in the vicinity of each electrode due to ion motion caused by the Coulomb force. The attraction of the ions present within the heterocharge layers to the adjacent asymmetric electrodes of a given pair causes bulk fluid motion in the desired direction.
This presentation will illustrate the EHD conduction pumping mechanism and its resultant transport characteristics. Specifically, the heat and mass transport resulting from EHD conduction pumping of a dielectric fluid in macro-, meso-, and micro-scales in the presence and absence of phase change (liquid/vapor) will be described. The recent results of two-phase heat transport experiments that were conducted on board variable-gravity parabolic flights will be presented. Furthermore, the EHD conduction driven liquid film boiling experiment that is scheduled for the International Space Station will be briefly presented.
From an application perspective, the EHD conduction pumping technology is expected to provide technological advances that will support NASA's various missions. EHD pumps are simple in design, light weight, non-mechanical, free of vibrations and noise, and they allow for effective active control of heat transfer and mass transport. EHD pumps require minimal electric power to operate. The resultant heat transport capacity is typically three orders of magnitude larger than the electric input power.
Yagoobi received his PhD degree from the University of Illinois at Urbana-Champaign in mechanical engineering. After receiving his PhD, he worked for Westvaco Corporation as a research engineer before joining Texas A&M University (TAMU). At TAMU, he was the Paul John Faculty Fellow as well as the TEES Senior Fellow. Yagoobi joined the Illinois Institute of Technology (IIT) in 2002 as the Chair of the Mechanical, Materials and Aerospace Engineering Department until 2011. In 2012, he joined WPI as the George I. Alden Professor and Head of Mechanical Engineering department.
Yagoobi’s research specialties are in enhancement of heat and mass transfer with EHD in small and large scales in the presence and absence of gravity, heat and mass transfer in porous media, and enhancement of heat transfer with phase-change materials. He has over 300 journal publications, book chapters, and peer-reviewed conference publications along with eight licensed patents. He is a fellow ASME, a fellow IEEE, and has received numerous national and international awards. Yagoobi is currently the associate editor of IEEE-IAS Transactions and was the associate editor for ASME Journal of Heat Transfer and Drying Technology journal.
Yagoobi sits on a number of international and national boards and panels including the Advisory Board of the Energy Engineering and Systems Analysis Directorate of Argonne National Laboratory. He is also a member of the Alumni Board, Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign.
Patrick Phelan, Emerging Technologies Program Manager, Building Technologies Office, Energy Efficiency and Renewable Energy, United States Department of Energy
"DOE’s Building Technologies Office: R&D Directions and Opportunities"
The US Department of Energy’s Building Technologies Office (BTO) supports R&D, deployment, and regulatory programs aimed at reducing primary (source) energy consumption in US buildings. The Emerging Technologies Program within BTO supports R&D activities across a wide range of end uses, including HVAC, lighting, windows, the opaque envelope, water heating, appliances, and sensors & controls, and in addition supports the development of modeling tools such as EnergyPlus and OpenStudio. Funding is provided both through direct support for the national labs and through Funding Opportunity Announcements (FOAs) that are generally open to all interested stakeholders. An overview is provided here of current research directions, as well as significant opportunities and priorities for future R&D support.
A copy of Dr. Phelan's presentation may be found here
Patrick (Pat) Phelan received his BS degree from Tulane University in New Orleans, his MS degree from MIT, and his PhD from UC Berkeley, all in mechanical engineering. Following a two-year post-doctoral fellowship at the Tokyo Institute of Technology, he started his academic career as an Assistant Professor at the University of Hawaii in 1992. In 1996 he moved to Arizona State University (ASU), where he is a Professor of Mechanical & Aerospace Engineering, and a Senior Sustainability Scientist. While on leave from ASU he served as the Director of the NSF Thermal Transport Processes Program from 2006 to 2008. He is again on leave from ASU, and is now the Program Manager for Emerging Technologies in the Building Technologies Office, Energy Efficiency and Renewable Energy, U.S. Department of Energy.
David Hu, Associate Professor, Department of Fluid Mechanics, Georgia Institute of Technology
"Ants That Can Flow Like A Fluid, or Spring Back Like A Solid"
Abstract: The wetlands of Brazil can be a dangerous place, especially if you are a fire ant. To keep their colonies together during flash floods, fire ants link their bodies together to build waterproof rafts. Ten thousand ants can build a raft in under two minutes. The cluster of ants can flow like a fluid, or bounce back like a coiled spring, depending on the situation. We use time-lapse photography, CT-scanning and rheological force measurement to elucidate how ants perform these feats. Understanding how ants can actively change their material properties may inspire the design of new kinds of modular robots and synthetic materials.
A video of this work is in the NY Times here
Bio: Dr. David Hu is a mechanical engineer who studies the movement of animals. He is an Associate Professor of Mechanical Engineering and Biology and Adjunct Professor of Physics at Georgia Institute of Technology. His degrees were in mechanical engineering and mathematics at M.I.T. and his postdoctoral work was at the Courant Institute of Mathematical Sciences at New York University. Dr. Hu has been awarded the National Science Foundation CAREER award, Lockheed Inspirational Young Faculty award, and best paper awards from SAIC, Sigma Xi, ASME, as well as awards for science education such as the Pineapple Science Prize. He has published in Nature, Science, Nature Materials, PNAS, and his work has been featured in The Economist, The New York Times, Good Morning America, and in the film Fire Ants 3D: The Invincible Army. He is the author of the new book The Science of Animal Motion, to be published by Princeton University Press in 2016. He lives in Atlanta with his wife Jia and children, Harry and Heidi. More can be found at hu.gatech.edu.
John Martin, PhD Candidate, University of Pennsylvania
Advisor: Robert Mauck
2:00 pm, Reunion Hall, John Morgan Building
"Nanofibrous Disc-Like Angle Ply Structures for Total Disc Replacement in a Small Animal Model"
Lower back pain will affect 85% of individuals at some point of their lives and carries a socioeconomic price tag of $100 billion USD per year; intervertebral disc repair is the most common reason for orthopaedic surgery. Degeneration of the lumbar intervertebral discs leads to loss of normal spine function, is ubiquitous in the general population, and is strongly implicated as a causative factor in back pain. For these reasons, our lab has developed what we call disc-like angle ply structures (DAPS) for total disc arthroplasty; using an electrospinning procedure, the ordered hierarchical structure of the native annulus fibrosus can be replicated and then combined with a hydrogel nucleus pulposus replacement.
My global hypothesis for this work is that disc replacement with an engineered biologic substitute can restore function to the spine. Here, I describe a rat caudal spine (tail) model of total disc replacement as a platform to evaluate DAPS in vivo; I found that an external fixation system that immobilized caudal vertebrae at the site of implantation was required for DAPS retention and confirmed implant position by fluoroscopically tracking DAPS fabricated from a radiopaque scaffold. A detailed analysis of DAPS in vitro growth trajectory was then performed to select the best timepoint for implantation, and cell-seeded DAPS were subsequently implanted in the rat tail and evaluated by histological, mechanical, and MRI analyses. We found that DAPS successfully restored the mechanical properties of the native motion segment and identified adaptations of the implant to the in vivo environment; there was a depletion in glycosaminoglycan after implantation, structural modifications to the NP material that suggested degradation, and no evidence of vertebral integration. In tackling the first of these issues, I developed a pre-culture strategy that best primed DAPS for the in vivo environment; using a rat subcutaneous model, I found that implant phenotype was best imprinted using a media formulation consisting of a transient high dose of TGF-b3. In this work, the most promising finding was that DAPS replicated motion segment mechanical properties after implantation, qualifying my global hypothesis that engineered biological disc replacement is a real possibility.
Jeffrey Kysar, Professor of Mechanical Engineering and Chair, Department of Mechanical Engineering, Columbia University
"Two-Dimensional Materials: Mechanical Stiffness, Strength, and Reliability"
Two-dimensional materials are planar molecules of arbitrary extent that consist of one or possibly a few atomic layers. Graphene, the archetypal two-dimensional material, consists of a single close-packed array of carbon atoms. Another, molybdenum disulfide, consists of three atomic layers: a close-packed array of molybdenum atoms sandwiched between two close-packed arrays of sulfur atoms. Two-dimensional materials have many potential applications due to their unique electronic, optical and mechanical properties. The focus of this talk is on the mechanical properties of graphene and molybdenum disulfide. We will discuss methods to isolate two-dimensional materials via mechanical exfoliation and subsequently to make single crystal specimens via nanofabrication methods. An atomic force microscope or a nanoindenter is used to indent a freestanding circular film. The experimental results suggest the mechanically exfoliated single crystal materials to be free of defects. Thus, the breaking strengths of graphene and molybdenum disulfide represent their respective intrinsic strengths, or the maximum stress that a material theoretically can support. In fact the mechanical strength exhibited by graphene is in excess of 100 GPa, making it the strongest material ever characterized. We will also discuss a multiscale model of the stress-strain constitutive parameters of graphene and molybdenum disulfide based upon ab initio Density Functional Theory (DFT) calculations. The theory is implemented into the finite element method to validate the multiscale model against experiments. Finally we will discuss graphene grown by Chemical Vapor Deposition (CVD) using industrially scalable processes. The CVD grown graphene is polycrystalline, yet upon optimization of the CVD parameters, the strength of the polycrystalline graphene can achieve a very high fraction of the intrinsic strength of defect-free single crystal graphene.
Jeffrey W. Kysar is Professor and Chair of Mechanical Engineering at Columbia University. He received his B.S. degree from Kansas State University and his Ph.D. from Harvard University. He has been a Visiting Associate Professor at the École Nationale Supérieure des Mines de Paris.
His current research interests are in the field of mechanical properties of small-scale materials from a combined experimental, computational and analytical perspective. Recent projects by his research group include: experimental characterization and theoretical development of the non-linear elastic properties of graphene and other monatomic thin film materials such as molybdenum disulfide; fabrication of crack-free blanket films of nanoporous gold onto silicon wafers for incorporation into micro-electro-mechanical systems (MEMS); fundamental study of the deformation mechanisms of monazite (lanthanum phosphate) which is a ceramic that deforms plastically; as well as the development of novel methods to characterize the spatial variation of material defects within metals that are deformed plastically. In addition, he works in the field of Otolaryngology to develop surgical tools to access the cochlea intended to treat hearing and balance disorders.
In 2012 he received the International Journal of Plasticity Young Researcher Award. In 2010 Science Watch recognized him and his coauthors for “the most-cited chemistry report published in the last two years, excluding reviews”. In 2006, he received the Presidential Early Career Award for Scientists and Engineers (PECASE) at the White House. That same year he also was awarded the Early Career Scientist and Engineer Award from the Department of Energy (DOE) Office of Defense Programs. In 2001 he received the Faculty Early Career Development (CAREER) Award from the National Science Foundation.
November 17NO SEMINAR
Thursday, November 19: Special Seminar
10:45 a.m., Towne 337
Josue Sznitman, Assistant Professor, Department of Biofluids, Technion – Israel Institute of Technology
"Unravelling the Mysteries of Respiratory Flows in Deep Pulmonary Airways"
Over the past decades, our understanding of respiratory fluid mechanics characterizing the pulmonary acinar region of the lungs has been fundamentally revisited. Here, we discuss our current knowledge of respiratory airflows in the deep alveolated regions of the lungs and specifically their role in influencing the transport and fate of inhaled aerosols. We will characterize alveolar flow phenomena and the range of complex flow topologies that exist across alveolar cavities including the convective mechanisms known to generate kinematic irreversibility in the acinus, despite low-Reynolds-number respiratory flows. Using experimental microfluidic-based platforms mimicking the pulmonary acinar structures, in conjunction with computational fluid dynamics (CFD) simulations, we shed some new light on the intricate coupling that arises in the deep acinar airways between diffusive, convective and sedimentation mechanisms for aerosol deposition. Our novel microfluidic-based experimental approaches give new insight in resolving in vitro respiratory acinar airflows and aerosol dynamics at the real scale, with the aim of predicting the deposition of inhaled particles across the acinar region.
Josué Sznitman joined the Department of Biomedical Engineering at the Technion – Israel Institute of Technology, in October 2010 as a tenure-track Assistant Professor. Sznitman was named a Horev Fellow supported by the Taub Foundation, and was awarded the Marcella S. Geltman Memorial Lectureship Fund.
Sznitman graduated from MIT with a BSc in Mechanical Engineering in June 2002. His Senior Thesis in the field of heat transfer was supervised by Prof. Bora Mikic. Under the supervision of Prof. Thomas Roesgen, he earned a Dipl.-Ing degree in Mechanical Engineering in June 2003, followed by a PhD in December 2007 at the ETH Zurich (Swiss Federal Institute of Technology). For his Master thesis, Sznitman was honored with an ETH Medal (2004); his doctoral work was awarded the ETH Silver Medal for outstanding dissertation as well as the 2008 Research Award from the Swiss Society of Biomedical Engineering (SSBE).
In January 2008, Sznitman came to the University of Pennsylvania as a Postdoctoral Fellow under the supervision of Prof. Paulo Arratia (Dept. Mechanical Engineering & Applied Mechanics). In January 2009, he joined the Dept. of Mechanical & Aerospace Engineering at Princeton University as a Lecturer and Research Associate, appointed by the Princeton Council of Science & Technology. During his appointment at Princeton (Jan 2009 – Aug 2010), Sznitman was mentored by Prof. Alexander J. Smits.
Sznitman’s general research interests lie in small-scale biofluid phenomena, animal locomotion, physiological flows, experimental flow visualization techniques, and image processing. Sznitman has received several honors including a Young Research Award for his contribution to Swiss Pediatric Research (2005) and a Young Scientist Award at the 12th Internal Symposium of Flow Visualization (2006). He is an elected member of Pi Tau Sigma (International Mechanical Engineering Society), Tau Beta Pi (The Engineering Society), and Sigma Xi (The Scientific Research Society). His professional affiliations include the American Physical Society (APS), the American Society of Mechanical Engineering (ASME), the Biomedical Engineering Society (BMES), and the European Society of Biomechanics (ESB).
December 8: Joint MEAM/GRASP Seminar
Robert J. Webster III, Associate Professor, Department of Mechanical Engineering, Vanderbilt University
"Can Needle-Sized Robot Tentacles Help Surgeons Save Lives?"
Thin, flexible robots able to bend and elongate can help surgeons reach deeper and more accurately into the human body than ever before, through increasingly smaller incisions. This talk will cover recent breakthroughs in design, control, and sensing that are rapidly pushing the boundaries of surgical robotics to smaller scales, greater accuracy, and more effective interaction with surgeons. Mechanics-based models of elastic robots provide the basis for these advancements, which in turn provide the raw materials necessary for building effective surgical robotic systems. These systems can offer autonomous, teleoperated, or hand-held surgeon-robot interactions. An important theme of the talk will be the fascinating process of partnering with surgeons to create new robots amenable to use in real-world operating room environments that have the potential to be powerful weapons in the fight against lung disease, brain tumors, hemorrhagic stroke, epilepsy, deafness, and urologic disorders.
Robert J. Webster III received his B.S. in electrical engineering from Clemson University in 2002, and his M.S. and Ph.D. in mechanical engineering from the Johns Hopkins University in 2004 and 2007. In 2008 he joined the mechanical engineering faculty of Vanderbilt University, where he currently directs the Medical Engineering and Discovery Laboratory. He serves on the steering committee for the Vanderbilt Initiative in Surgery and Engineering, which brings together physicians and engineers to solve challenging clinical problems. Prof. Webster's research interests include surgical robotics, medical device design, image-guided surgery, and continuum robotics. He is a recipient of the IEEE Robotics and Automation Society Early Career Award, the National Science Foundation CAREER award, the Robotics Science and Systems Early Career Spotlight Award, and the IEEE Volz award.