Abstract: Dermal scales appeared early in the evolutionary history of vertebrates, most notably in fishes. Their remarkable multi-functional roles include protection from predatory attacks, enhancement of locomotion, camouflaging and thermal regulation. This has led to a tremendous variation in scale type, material, shape, size and organization among species (e.g. fishes, snakes) as well as within species (different types of fish scales). This has led to a great deal of interest in their material properties. Less investigated is the role of the scales themselves as geometric units of high performance.  Interestingly, many remarkable behaviors lie in the geometrical form and distribution of the scales. Discretely segmented, geometrically pronounced units emanating from softer, slender substrates allows for a rich interplay of deformation, geometry and functions at multiple length scales underscoring structure-property synergy. Therefore, the primitive scale topology (exoskeleton form) appears across a much wider range of critical biological structures such as papillae on feline tongue, where they dramatically enhance gripping capacity and combine it with fluid wicking properties or on the surface of animal furs, where nanoscale scaly features are known to reduce microbial fouling, or aid in aerodynamic functions. Testament to their remarkable structure-properties enhancements, it is difficult to find slender biological structures that do not exploit some type of concerted external surface texture. These features result in a number of unusual mechanical behavior such as small strain reversible nonlinearities and quasi-rigid locking behavior in bending and twisting deformations even when friction is negligible. When friction is significant, unexpected dissipation and damping behaviors arise. Furthermore, stiff plate like scales on a soft substrate can give rise to perceptible change in indentation response, which can quickly transition away from the Hertzian regime. Since the main sources of such nonlinearities are geometry and interface dictated, such extreme mechanical behaviors can be easily programmed and functionally graded using additive manufacturing, which can be exploited for diverse applications such as multifunctional structures, robotic exoskeletons, prosthetics, flexible electronics and protective coatings.

Biographical Sketch: Dr. Ranajay Ghosh is an Assistant Professor in the department of Mechanical and Aerospace Engineering (MAE) and the Center for Advanced Turbine and Energy Research (CATER) at UCF. He directs the Complex Structures and Mechanics of Solids (COSMOS) Laboratory. His research focuses on the behavior of deformable solids and computational mechanics particularly focusing on modeling multiscale and multiphysics phenomena in heterogeneous and topological solids. Prior to his appointment at UCF, Dr. Ghosh earned his PhD from Cornell University, Ithaca, NY where he was awarded the Harriet-Davis doctoral fellowship. During his PhD he also carried out research at the General Electric’s (GE) Global Research Center at Niskayuna, New York where he was the recipient of GE’s global recognition award for outstanding performance. He subsequent carried out postdoctoral research at the Rensselaer Polytechnic Institute and Northeastern University.  Dr. Ghosh’s research work has led to over 45 peer reviewed journal publications including several cover arts and media coverage in Discovery, Newsweek and the New York Times.  Dr. Ghosh’s research is primarily funded by Siemens Energy, the US Department of Energy (DoE) and the National Science Foundation (NSF).

Abstract: Demand of batteries keeps increasing as electronic devices get widespread and fossil-based systems are being replaced by electricity-based systems. Lithium-ion battery has been considered one of the most promising power sources for mobile and transportation systems, but it faces challenging issues of high cost, low capacity (i.e. short operation hours or driving ranges), and safety issues. Therefore, it is necessary to find the break-through technologies to resolve those issues. In this talk, two promising electrochemical systems will be introduced: aluminum-air battery and multi-valent catalytic flow battery. Aluminum is cheap and abundant, benign to the environment, and stable in moisture. But, due to the problems of self-corrosion and formation of inert oxide film on the surface of aluminum during cell operation, the Al-based rechargeable battery could not reach commercialization stage. Ionic liquid which is a molten salt in liquid form at room temperature is getting intense attention recently as a promising electrolyte to resolve those issues. In this talk, discussion will be made about the effect of the oxide film on performance of the ionic-liquid based Al-air battery and how to control the film with results of research conducted in Dr. Cho’s group at Northern Illinois University (NIU) through experiment and physic-based modeling.Redox flow battery (RFB) is enjoying a renaissance with substantial achievement of research, altering it ultra-high performing and high energy dense system. And also, the excellent feature of RFB decoupling energy from power has been applied as a key design factor to overcome the challenging issues of conventional battery systems. In this talk, new promising “redox-mediated bromate based flow battery” which has theoretical energy density greater than lithium ion battery will be introduced, and characteristic “auto-accelerated” catalytic electrochemical reaction coupled with chemical reaction will be discussed in detail.

Biographical Sketch: Dr. Kyu Taek Cho is an assistant professor of mechanical engineering at Northern Illinois University, Dekalb, IL. He has around 20-year experience in the electrochemical system through works in national lab, industry, and academy. He had worked at Lawrence Berkeley National Lab as a postdoc and then a research staff before he joined NIU in 2014. He also has industrial experience as a research engineer at Hyundai Motor Company, S. Korea to develop a fuel stack for the application to vehicle. Dr. Cho has Ph.D. achieved from Pennsylvania State University under guidance of Professor Matthew Mench. Dr. Cho is a director of Electrochemical Energy Lab at NIU to conduct the fundamental research of advanced electrochemical and thermal energy systems.

Abstract: In standard seakeeping simulations of a ship in irregular seas, the rigid body motions of the ship are computed using a set of semi-analytic integro-differential equations, which model the response of the ship including non-linear and history dependent forces.    Using this type of model allows one to model the response of the ship in incident irregular waves, corresponding to a sea state defined by its significant wave height, H_s, peak spectral period, T_p, dominant wave direction, θ₀, and spectrum type, while allowing fairly quick simulation of the response using standard numerical integration methods.  In this work, we develop and apply such a model to compute ship motions for a large number of sea states. Then, we perform the inverse problem of determining the governing sea state parameters by training a Neural Network, based on the time histories of ship response in roll, pitch, and heave computed with the model. The estimator is then validated against physical model test experiments conducted using irregular waves generated in a towing tank to demonstrate that the numerical model is sufficient for training the Neural Network using simulated data.  The main rationale for this work is to develop a low-cost method for small vessels to estimate local sea state conditions in order to avoid operations in dangerous sea states, however the same techniques could be applied in general to transiting vessels to obtain local and continuous sea state measurements for general science purposes or other uses. 

Biographical Sketches: Jason M. Dahl is an Associate Professor in the Department of Ocean Engineering at the University of Rhode Island.  Dr. Dahl (PhD, Ocean Engineering, MIT; B.S., Naval Architecture and Marine Engineering, Webb Institute) is an expert in fluid-structure interactions and floating body dynamics, with particular expertise in the flow-induced vibration of underwater structures. Dr. Dahl has extensive experience as an experimentalist with towing tank operations, dynamic testing, and quantitative flow visualization.

Stephan T. Grilli is a Distinguished Professor and Chair, in the Department of Ocean Engineering at the University of Rhode Island.  Dr. Grilli (PhD, Ocean Engineering, M.S. Physical Oceanography, M.S. Civil Engineering, University of Liège) has a broad background in Computational Fluids Dynamics related to free surface and wave-structure interaction problems in coastal, naval and ocean engineering, and oceanography. Dr. Grilli has over 30 years of experience with developing higher-order boundary element models and viscous simulations for the solution of free surface potential flows for wave propagation and wave-structure interactions including the modeling of tsunami wave propagation, ship seakeeping in waves, wave breaking, and wave energy systems.

Abstract: Several studies have documented the importance of metabolism to osteoarthritis. This seminar will discuss recent advances in understanding how chondrocytes alter their metabolism in response to in vitro mechanical loading.  Furthermore, metabolomic studies of osteoarthritic  synovial  fluid  will  be  discussed in the  context  of  early  detection  and  phenotypes  of osteoarthritis.

Biographical Sketch: Ron June has longstanding research interests in osteoarthritis and biomechanics related to improving human health.  At Dartmouth College he studied Engineering Sciences focused on biomechanics and developed a novel wrist protection strategy, contributed to the design and manufacture of a system for monitoring 3D head accelerations in helmeted sports, and helped to develop a finite element model to understand the biomechanics of spinal pain in rats.  As a graduate student at the University of California, Davis, Dr. June studied cartilage biomechanics.  Specifically, he investigated a novel mechanism of cartilage flow-independent viscoelasticity.  During the course of this project, he discovered novel biomechanical phenomena and made several experimental observations that are consistent with polymer dynamics as a potential physiological mechanism of cartilage viscoelasticity.  As a postdoctoral fellow, Dr. June has implemented a surgical model of  mouse  osteoarthritis  and  studied  protein  transduction.    He  developed  a  pH-sensitive  system  for intracellular delivery of macromolecules and has investigated protein transduction in cartilage and chondrocytes.   Dr. June’s laboratory at Montana State University was completed in March 2012, and his research involves applying modern techniques to advance understanding of osteoarthritis and joint biology. He has applied both targeted and untargeted metabolomic profiling to mechanobiological questions. Dr. June has been named a GAANN Fellow, NIH Kirchstein Fellow, and the Montgomery Street Scholar by the ARCS Foundation.  His long-term research interests lie in understanding cartilage and joint mechanobiology to develop novel therapeutic strategies for joint disease.

Abstract: This presentation will introduce two new ideas for laser diagnostics applicable to combustion and propulsion and two new ideas for high-speed imaging of combustion phenomena in a shock tube.  The first laser diagnostic to be discussed is Spectrally-Resolved Fluorescence, in which a narrow-linewidth wavelength-tunable laser source is rapidly scanned over one or more absorption transitions, allowing collection of a spatially resolved laser-induced fluorescence signal that reflects the strength and shape of the absorption feature.  This diagnostic can potentially provide accurate determinations of temperature, pressure, flow velocity and the concentration of the absorbing species.  The example to be presented will be of OH excited and detected in the ultraviolet (UV).  The second new laser diagnostic utilizes a narrow-linewidth infrared laser source that can be scanned rapidly over a relatively wide wavelength range, thereby enabling acquisition of spectral absorption cross-sections over a full rovibrational absorption band of combustion-relevant species in a short time (a few milliseconds), compatible with the test times available in reflected shock wave experiments.   The goal of the experiments is to generate a unique data base for cross-sections over a wide range of temperature, not feasible in a heated static cell.  Two other experiments will be presented, both based on imaging of shock-heated gases. In the first experiment, high-speed imaging is used to visualize and characterize aspects of inhomogeneous ignition that can occur in reflected shock wave experiments of hydrocarbon fuel ignition; such inhomogeneous ignition is undesirable and can contaminate data sets aimed at providing high-quality information on ignition delay times.  As a second example of imaging in a shock tube, a new experiment will be introduced that measures the burning velocity of a flame produced by laser ignition of combustible gases behind a reflected shock wave.  The objective is to enable flame speed measurements at elevated temperatures not accessible with conventional flame speed techniques.  Such conventional methods are limited by the partial reaction of the mixture that occur during the lengthy period of preparing reactive mixtures, whereas with a shock tube experiment the time interval between shock wave heating and ignition can be adjusted to be quite small.  Results obtained in heptane-air flames provide clear evidence of cool flame effects not previously seen in flame speed experiments.  In current work, the observation of flame speed from the time-resolved position of chemiluminescent emission is also being augmented by various laser absorption diagnostics to additionally characterize the burned gases behind the flame.

Bio Sketch: Professor Hanson received his bachelor’s degree from Oregon State University in mechanical engineering and his doctoral degree from Stanford University where he currently holds the Woodard Chair in Mechanical Engineering.  He has been an international leader in the development of laser-based diagnostic methods for combustion and propulsion, and in the development of shock tube methods for accurate determination of chemical reaction rate parameters needed for modeling combustion and propulsion systems, and together with his students he has made several pioneering contributions that have advanced the pace of propulsion research and development worldwide.  He is a Fellow of AIAA, ASME and OSA, a member of the National Academy of Engineering, and a recipient of gold medal awards from the Combustion Institute, the Institute for Dynamics of Explosions and Reactive Systems, and multiple gold medals from the AIAA. He has published over one thousand papers and advised over 100 doctoral students, including 31 now holding faculty appointments around the world.