Archives—October 2014

ME-EM Graduate Seminar: Cavitation-Induced Damage in Brain Tissue and Surrogates: Relevance to TBI

oct30The ME-EM Graduate Seminar speaker on Thursday, October 30th at 4:00 in 103 EERC will be Dr. Ghatu Subhash from the University of Florida, Gainesville.

The title of his presentation will be ‘Cavitation-Induced Damage in Brain Tissue and Surrogates: Relevance to TBI’.

Traumatic brain injury (TBI) has reached epidemic proportions in US. Around 1.7 million people are diagnosed with TBI each year. While a majority of these injuries are due to physical blows that may occur because of a fall or during an athletic activity, blast-induced mild traumatic brain injury (bmTBI) is specific to soldiers who are exposed to frequent improvised explosive device (IED) blasts in a hostile environment. A blast wave consists of a high pressure front followed by a negative pressure tail. It is commonly believed that only the high pressure front causes significant damage to the brain tissue. In recent years, new evidence has emerged revealing that extensive cavitation indeed occurs in brain tissue due to the negative pressure that immediately follows the high pressure front in the blast wave. The negative pressure initiates cavitation bubbles which collapse and release shock waves, and cause significant local neuronal and astrocyte damage in sensitive areas of the brain. The current research focusses on investigating this specific phenomena in brain tissue and surrogates (e.g., gels). The first goal of this research is to develop an experimental facility to characterize cavitation in a simulated brain environment and measure associated deformation during bubble growth and collapse on a tissue surrogate. The second goal is to quantify the neuronal and astrocyte injury when a brain tissue is exposed to blast waves. A novel experimental facility has been developed to visualize controlled cavitation under high-rate stress wave loading, whose pressure profile mimics that of a blast shock wave, i.e., it contains a high pressure component followed by a negative pressure component. Highly sensitive pressure sensor measures the pressure inside the fluid filled chamber where a single air bubble is introduced at a specified location. Upon arrival of the pressure wave the bubble grows rapidly and collapses. Negative pressure magnitude, which dictates bubble growth rate and its final size, can be controlled. A high speed digital camera with frame rates up to 300,000 per second was employed to capture the tissue deformation characteristics. Digital Image Correlation (DIC) technique was employed on the gel tissue to capture the time varying strain field during the bubble growth, collapse, and subsequent generation of local shock wave. The relationships between the incident pressure, cavitation bubble dynamics, and induced deformation within a tissue surrogate during shock loading are investigated. In the next step, live brain tissue slices extracted from rats were tested with specified areas (e.g. Hippocampus) exposed to single bubble cavitation. Postmortem histological studies have been performed to quantify neuronal and astrocyte damage as a function of shock pressure. Our experiments have shown that the shock-induced cavitation bubble growth and collapse can be captured using this experimental facility and the results indicate that sensitive tissue damage indeed occurs due to the shock wave generated by cavitation bubble collapse.

Professor Subhash obtained his MS and PhD degrees from University of California San Diego and conducted post-doctoral research at California Institute of Technology, Pasadena, CA. He joined the faculty of Michigan Technological University (MTU) in 1993 and then moved to University of Florida (UF) in 2006. He has received numerous awards for excellence in teaching, research and professional service, including the ‘Significant Contribution Award’ American Nuclear Society – Materials Science and Technology Division (2014), Fellow of Society of Experimental Mechanics (2014) ‘Technology Innovator Award’ University of Florida (2014), UF Research Foundation Professor (2013), College of Engineering Teacher/Scholar of the year (2013), ‘2011 Researcher of the Year’ Mechanical and Aerospace Engineering Department, Second Place of the Best paper Awards at the 31st Annual American Ceramic Society meeting (2008), Michigan Tech Distinguished Research Award (2005), ASME Fellow (2004), ASME Student Section Advisor Award (2003), Society of Automotive Engineers (SAE) Ralph R. Teetor Educational Award (2000), American Society of Engineering Education (ASEE) Outstanding New Mechanics Educator Award(1996), and Distinguished Teaching Award at MTU (1994). He is an Associate Editor of Mechanics of Materials, Journal of the American Ceramic Society, Experimental Mechanics and ASME Journal of Engineering Materials and Technology. He has graduated 21 PhD students and is currently advising 12 PhD students in various fields related to processing, microstructural characterization and multiaxial behavior of advanced materials including ceramics, metals, composites, gels and brain tissue. He has authored around 150 peer reviewed journal papers and 70 conference proceedings. He has filed for 8 patent applications in various fields of material processing, mechanical testing, food packaging, and protective helmet design. His recent invention on fluid filled energy absorbing cushions for protective equipment has received widespread attention from major TV networks (Fox , CBS and 40 other local TV channels), and radio stations (including NPR) and articles by Reuters, ASEE morning bell and many local newspapers. He has given numerous invited lectures and seminars at many universities and international conferences.

ME-EM Graduate Seminar: Local Aggregation Characteristics and Visualization of Intermediate Layers during Evaporation of Nanofluid Droplets

oct23The ME-EM Graduate Seminar speaker on Thursday, October 23rd at 4:00 in 103 EERC will be Dr. Dong Hwan Shin a post doc in the Mechanical Engineering Department at Michigan Tech.

The title of his presentation will be ‘Local Aggregation Characteristics and Visualization of Intermediate Layers during Evaporation of Nanofluid Droplets’.

Recently, nanofluids (NF) are of substantial interest because of their potentials in exhibiting improved thermal performance. Thus, nanofluids are expected as the next generation of cooling fluids for automobiles and electronic devices. One of Dr. Shin’s research interests is about characterization of nanofluid droplet evaporation by using confocal and regular inverted microscopic systems. This presentation will introduce his recent work regarding the nanofluid droplet evaporation: Evaporation characteristics of nanofluid droplets with various volume fractions of 50 nm alumina (Al2O3) particles are experimentally examined. The effect of particle concentrations on droplet evaporation rates is examined. The corresponding wettability changes and the total evaporation time are also examined. Besides, he will also introduce the spatial non-uniformity of suspended nanoparticles in the droplet caused by the local aggregation visualized by using the inverted microscope system. The results show that the effective thermal conductivity should be changed according to the non-uniform distribution of nanoparticles inside a droplet on the surface. Next, the contact lines of nanofluids droplets during evaporation are visualized using a high-speed reflected mode slit-confocal. The present work deals with a challenging issue on the experimental visualization of the intermediate layer because the conventional optical approach cannot visualize this layer due to the optical limitation. The intermediate layer thickness varies with time during evaporation, which is observed based on the fringe pattern analysis. Those results show the feasibility of using fringe patterns of contact lines can provide instability of a contact-line region in the thin film and further explain heat and mass transfer in this region.

Dr. Dong Hwan (DH) Shin is a post-doctoral research scholar of Mechanical Engineering-Engineering Mechanics at Michigan Technological University. He received his B.S., M.S. and Ph.D in Mechanical Engineering in Chung-Ang University (CAU) in 2008, 2010 and 2014, respectively. He has already been to MTU as a visiting scholar three times in 2010, 2012 and 2013. His research interests are nanofluids and its applications, micro-droplet evaporation and its applications, flame spray and its applications, and computational fluid dynamics. He has published 17 journal papers and 22 proceedings.

ME-EM Graduate Seminar: Automotive Powertrain Control: Opportunities and Challenges

oct16The ME-EM Graduate Seminar speaker on Thursday, October 16 at 4:00 in 103 EERC
will be Dr. Chen-Fang Chang of GM Global Research & Development.

The title of his presentation will be ‘Automotive Powertrain Control: Opportunities and Challenges’.

Advanced powertrain systems are being introduced into passenger vehicles to meet regulatory and customer demands, simultaneously increasing fuel economy, reducing emissions and enhancing driveability. As the powertrain systems become more sophisticated, it will force a dramatic increase in control complexity and calibration effort. This presentation will detail the challenges facing automotive control community and the approaches a control engineer can take to confront these challenges. IC engine controls will be used to exemplify a whole engine controller development cycle. Future outlook will also be provided.

Dr. Chang is currently the Lab Group Manager of the Propulsion Control Systems Group at GM Global R&D. Since joining GM in 1994, he has worked on cylinder-pressure-based engine controls, diesel aftertreatment controls, HCCI engine controls, and, most recently, information-rich propulsion controls. Dr. Chang received his Ph.D. degree in Mechanical Engineering with minor in Electrical Engineering from Stanford University. He holds 43 US patents and has numerous technical publications. He is the recipient of 2013 ASME Rudolf Kalman Award and 2001 SAE Arch T. Coldwell Merit Award.

ME-EM Graduate Seminar: Space Tethers, Small Satellites, and System Engineering

oct9The ME-EM Graduate Seminar speaker on Thursday, October 9 at 4:00 in 103 EERC will be Dr. Nestor Voronka, Principal, M42 Technologies.

The title of his presentation will be ‘Space Tethers, Small Satellites, and System Engineering’.

This seminar will present an overview of space tether technology, its applications, and the
results of space tether missions to date. Space tethers present interesting system engineering challenges and in particular when integrated into small satellites. System engineering challenges
of both large and small spacecraft systems will be discussed along with some lessons learned and recommendations.

Dr. Nestor Voronka is the Principal of M42 Technologies, which develops, advanced technologies, provides alternative and relevant solutions to space and aerospace challenges and is currently focused on developing project solutions and flight systems for the DoD, NASA and commercial space customers. From 2003 to 2013 Mr. Voronka served as the Chief Technologist and VP of Tethers Unlimited, Inc where he led various product and technology development efforts designing space tether systems, nanosatellite components, propulsion systems, RF systems, spacecraft antennas, 3D printable radiation shielding, and UAV towed sensor systems. Mr. Voronka was the lead engineer responsible for the design, development, testing, and delivery, and operations of the MAST 3U CubeSat experiment that launched in April 2007. From 1996 to 2003, Mr. Voronka was Chief Engineer at Cybernet Systems Corp. where he was led the development of products and technologies in a number of areas including computer networking, force feedback devices, motor control, motion capture, machine vision, electro-optics, inertial navigation, aviation systems, and medical devices. While at the UM-Space Physics Research Lab 1991-1996 first as a student and then a staff engineer, Mr. Voronka worked the Tethered Satellite System (TSS-1R) that flew on the Space Shuttle Columbia STS-75 flight in February of 1996. Mr. Voronka has two Master’s degrees from the University of Michigan in Electrical Engineering in the areas of electromagnetics, and Signal/Image Processing.

Michigan Tech students join in international PACE contest

PAMDMichigan Tech students participated with other university students in an multi-year international competition to design a Portable Assisted Mobility Device (PAMD) through the Partners for the Advancement of Collaborative Engineering Education (PACE) program. There were 7 international teams and 45 universities from around the world involved, showing the “collaborative engineering” purpose of the PACE program. At the 2014 PACE Global Annual Forum in Turin (Italy) the projects were evaluated by an international team of judges including GM/Opel, Siemens, PLM Software, Autodesk, Oracle, and HP.
The winning PAMD team included RWTH Aachen University, TU Darmstadt (both in Germany), Michigan Technological University, the University of Cincinnati and the ITESM Estado de Mexico.   Continue reading

ME-EM Research Shown

IMG_1686dSeveral examples of the diverse research at Mechanical Engineering-Engineering Mechanics department were shown at the R.L. Smith Building on Tuesday, Sept. 30. MEEM faculty and graduate students presented posters describing on-going and future research activities.

Some of the examples of projects included nonlinear and autonomous vehicles research, agile ankle-foot prosthesis, an award winning portable assisted mobility device, ultra low sulfur and green diesel fuel comparison, and interdisciplinary research in geology and mechanical engineering on shock waves generated during explosive volcanic eruptions. Continue reading