Seminars are on Fridays at 12:00 pm in Engineering East Hall, Room E3229 or Engineering West Hall, Room 106 (as specified). Refreshments are typically provided. Please see the schedule below for our list of seminars.

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Spring 2018

Additional details to be determined

John Fortner, Ph.D.
International Center for Engergy, Environment and Sustainability
Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis

Professor Michael Czabaj, Ph.D.
University of Utah

The NBSR: Celebrating 50 Years of Neutron Research
Robert Williams, Ph.D.
Nuclear engineer at the NIST Center for Neutron Research

12:00 - 1:00 P.M.
Friday, April 13
Engineering East Hall, Room E3229

Fifty years ago, December 7, 1967, the National Bureau of Standards Reactor, the NBSR, was made critical for the first time. The bureau had just completed the move to its new campus in Gaithersburg, Maryland from its cramped laboratories in Washington, DC. The reactor was one of three state of the art neutron sources to start up at about the same time; the HFBR at Brookhaven and the HFIR at Oak Ridge were the other two. The NBSR was initially licensed to operate at 10 MW by the Atomic Energy Commission, and then relicensed in 1984 by the Nuclear Regulatory Commission with a power increase to 20 MW. It was again relicensed in 2009 for 20 more years.

The reactor was designed with a very large thimble, 55 cm ID, to accommodate a D2O cold neutron source, installed in 1987, and the success of which led to the construction of the guide hall and eventually to the establishment of the NIST Center for Neutron Research, NCNR. The facility has grown tremendously in the years since the first cold neutrons were directed to the guide hall in 1990. A liquid hydrogen cold source replaced the D2O source in 1995 with a six-fold gain in flux, and within a few years there were about 15 instruments on the 7 original guides. A second expansion project was launched in 2007 that has added a new guide hall with 5 more guides, and a second LH2 cold source in one of the thermal beam tubes for the Multi-Axis Crystal Spectrometer. Through it all, the NBSR has provided beams of thermal and cold neutrons for research in materials science, fundamental physics and nuclear chemistry. NCNR has become a world-class research facility operating 28 instruments, 22 of them using cold neutrons.

A brief history of the NBSR, a description of the NCNR facility, and prospects for the future will be presented. An excellent account of the growth of the NCNR from the early days to the present was written by Jack Rush and Ron Cappelletti.

Since 1989, Dr. Williams has been employed at the NIST Center for Neutron Research, working in the areas of reactor physics and cold neutron source development. He leads the team responsible for the design, fabrication, installation, testing and operation of the two liquid hydrogen cold sources in the NIST research reactor, the NBSR. Computer simulations of neutron and gamma-ray transport were needed to optimize the cold source performance and estimate the nuclear heat load on the cryogenic refrigerator. The MCNP models of the NBSR were also used in physics and safety analyses presented to the NRC in support of license renewal, and more recently, to study the conversion to low-enrichment uranium fuel. He received his Ph. D. in Nuclear Engineering from the University of Illinois.

Airway structure and function of the human airways studied via 3D imaging and 3D printing
Filippo Coletti, Ph.D.
Assistant Professor; University of Minnesota

12:00 - 1:00 P.M.
Friday, April 6
Engineering West Hall, Room W106

The details of the air motion through the lungs critically affect our respiration. Understanding the influence of the patient-specific airway anatomy on the inspiratory flow features is therefore necessary for treating pathological airway disease, designing more effective mechanical ventilators and inhalers, and predicting the effect of exposure to airborne pollutants. The available information is, however, scarce. The representation and modeling of the human bronchial tree is often based on classic but dated morphometric studies. Complex vortical air motions are believed to ensue in the bronchi due to their curvature and bifurcations, but their intensity and persistence is debated. Given the costs and technical difficulties associated to in vivo clinical studies, much of what we know comes either from experiments in highly idealized airway models, or from numerical simulations.

In the first part of this talk, I will present an analysis of the bronchial tree morphology obtained by X-ray computed tomography from a cohort of healthy subjects, highlighting several results that challenge the commonly assumed anatomical canons. I will also discuss measurements of the volumetric flow in 3D printed subject-specific airway replicas obtained by Magnetic Resonance Imaging. These enable direct testing of fundamental relationships between structure (anatomy) and function (airflow) employed in many analytical models of the respiratory activity. In the second part of the talk, I will use the same tools to compare anatomy and airflow features in smoking subjects with comparable respiratory functionality, but who later developed very different pulmonary capacity due to obstructive disease. The results indicate that the bronchial anatomy and the consequent respiratory flow features are correlated with the progression of the airway disease, possibly due to the fate of inhaled particles. On the one hand, this suggests that imaging-based biomarkers may allow pre-symptomatic diagnosis of disease progression. On the other, it paves the way to designing patient-specific strategies for inhalation drug delivery and ventilation.

Filippo Coletti is Assistant Professor of Aerospace Engineering & Mechanics at the University of Minnesota, where he has been since 2014. Previously he was postdoctoral fellow at Stanford University, and performed his doctoral studies at the von Karman Institute (Belgium) and at the University of Stuttgart (Germany) where he obtained his PhD in 2010. He is the recipient of the NSF CAREER Award, the 3M Non-Tenured Faculty Award, and the McKnight Land-Grant Professorship. His research interests revolve around the transport of particles in turbulent and vortical flows, leveraging a wide spectrum of experimental approaches and with applications to both biomedical and environmental problems. His research is funded from the National Science Foundation, the National Institute of Health, the Army Research Office, the Office of Naval Research, the State of Minnesota, and industry partners.

Dynamic Assembly and Active Propulsion of Asymmetric Particles under Externally Applied Fields: A Path Towards Functional Materials and Intelligent Colloidal Robots
Ning Wu, Ph.D.
Associate professor, Colorado School of Mines

12:00 - 1:00 P.M.
Friday, March 30
Engineering West Hall, Room W106

Colloids are important for our daily life and modern technologies. Among which colloidal particles with asymmetric properties in geometry, surface functionality, and chemical composition emerge as an important family of the colloidal genome. Scientifically, both in-and far-from-equilibrium behaviors of these micro/nano-particles are fundamentally different from conventional particles because of their broken symmetry in particle properties, colloidal interactions, and surrounding hydrodynamic flow. Technologically, synthetic motors based on asymmetric particles that can actively sense the environment, capture targets, and deliver cargoes could revolutionize many modern technologies including targeted drug delivery, cell manipulation, intelligent sensors, and miniaturized surgeons. In this talk, we will report our recent studies of dynamic assembly and active propulsion of asymmetric colloids that are driven by externally applied electric or magnetic fields. The new assembled structures and propulsion mechanisms revealed here not only provide insights in the non-equilibrium physics for active soft matter but also suggest new routes for making colloidal-based robots for cargo capture and delivery within a wide range of solution conditions.

Dr. Ning Wu joined Colorado School of Mines (CSM) as an Assistant Professor of Chemical Engineering in fall 2010 and was promoted to associate professor with tenure in 2016. He holds a B. Eng. in Chemical Engineering from the National University of Singapore, and a Ph. D in Chemical Engineering from Princeton University. Before joining CSM he worked at Harvard University as a postdoctoral researcher. His research interest lies in controlling the structures of colloidal particles at different length scales, which are important for emergent dynamics of out-of-equilibrium colloidal systems, multi-functional micro-motors, development of efficient photovoltaics, novel colloidal emulsifiers, as well as biomedical diagnostic/therapeutic systems. He received National Science Foundation CAREER award in 2015. His recent work have been published on PNAS and PRL, featured on the cover of Advanced Functional Materials, and selected in spotlights in JACS.

Structural Magnetostrictive Alloys: From Flexible Sensors to Energy Harvesters and Magnetically Controlled Auxetics
Alison Flatau, Ph.D.
Professory and Associate Chair, University of Maryland

12:00 - 1:00 P.M.
Friday, March 23
Engineering West Hall, Room W106

Novel sensors and energy harvesting transducers take advantage of the significantly expanded design space made possible by recent advances in structural magnetostrictive alloys. These alloys can be machined and welded, have high fracture toughness, and can actuate, sense, and carry load while subjected to tension, compression, and bending. The talk includes an introduction to magnetostrictive materials and transduction, and a discussion on the use of low-cost rolling and annealing methods in lieu of more costly crystal growth methods for making bulk iron-gallium (Galfenol) and iron-aluminum (Alfenol) alloys. The process of using magnetostrictive materials to convert mechanical energy into magnetic energy and then into electrical energy is explained and demonstrated using sensors and energy harvesting devices as examples. Examples of magnetostrictive devices include prototypes ranging in size from nanowire-based pressure sensors to huge structures floating in the ocean that convert wave energy into electrical power for “community-scale” energy needs. The recent discovery of a particularly unique attribute of these alloys, their auxetic behavior, will also be discussed. In both Galfenol and Alfenol, both strain and magnetic fields can produce simultaneous increases in lateral and longitudinal dimensions, with measured values of the resulting Poisson ratio being not only negative, but also as low as −2 in some cases. Mechanical, aerospace, and civil engineers should find the discussion on the use of magnetic fields to control auxetic behavior quite interesting.

Alison B. Flatau received the bachelor’s degree in chemical engineering from the University of Connecticut, Storrs, CT, USA, and the M.S. and Ph.D. degrees in mechanical engineering from the University of Utah, Salt Lake City, UT, USA. She taught engineering mechanics at Iowa State University, Ames, IA, USA, for eight years.

She served as the Program Director for the Dynamic Systems Modeling, Sensing, and Control Program at the National Science Foundation during 1998–2002. She joined the Department of Aerospace Engineering, University of Maryland, College Park, MD, USA, in 2002, where she was the Associate Dean of research for the Clark School of Engineering during 2009–2015. She was with the National Small Wind Systems Test Center (now the National Renewable Energy Laboratory), Golden, CO, USA, for four years, where she was a Senior Research Engineer of the Wind Energy Conversion Systems Test Program. She was an ADVANCE Professor with the University of Maryland during 2011–2013. Her current research interests include smart materials and structures, with emphasis on magnetostrictive actuator and sensor technologies, from the nano- to the macroscale. Prof. Flatau received the Clark School of Engineering’s Faculty Service Award in 2009, the Women in Aerospace Aerospace Engineering Educator of the Year Award in 2010, the SPIE Smart Structures and Materials Lifetime Achievement Award in 2010, and the American Society of Mechanical Engineers (ASME) Adaptive Structures and Materials Systems Prize in 2013. She was a Dresden Fellow while on sabbatical with the Technical University of Dresden, Germany, in 2016. She became a fellow of the ASME in 2006 and the American Institute of Aeronautics and Astronautics in 2013.

Bridging Computational Materials Science and Structural Mechanics: A New Paradigm for Predictive Simulation
Caglar Oskay, Ph.D.
Associate Professor, Vanderbilt University, Nashville, TN

12:00 - 1:00 P.M.
Friday, March 16
Engineering West Hall, Room W106

Over the past couple of decades, tremendous effort has been devoted to the development of multiscale computational modeling and simulation strategies for physics-based prediction of structural response. Among these strategies, concurrent multiscaling holds great potential in effectively bridging the “material” response to that of the “structure”. Yet these approaches are so computationally intensive that they remained within the academic realm, and have yet to make impact on realistic engineering problems.

We propose the Eigendeformation-based Reduced Order Homogenization Method (EHM) for computationally efficient and accurate concurrent multiscale analysis. We build and demonstrate this method to predict the response of structures made of polycrystalline materials, where crystal plasticity finite element (CPFE) simulations are concurrently coupled to a large scale structural analysis. EHM employs the idea of precomputing certain information on the material microstructure such as the influence functions, localization operators and coefficient tensors through RVE scale simulations, prior to the macroscale analysis. The reduced order modeling is achieved by being selective in what “physics” we choose to embed at the fine scales, as well as by developing sparse and scalable computational algorithms that can very efficiently solve the resulting multiscale systems.

We demonstrate the efficiency of the proposed approach in simulating the response of large structural problems (resolving each grain throughout the domain of the structure!) with modest computational resources. We also demonstrate the ability of the reduced order model to accurately capture the local, grain-scale features (grain level stress, strain, dislocation density evolution) and failure initiation mechanisms in the context of a high-performance titanium alloy (Ti-6242S).

Caglar Oskay is Associate Professor of Civil and Environmental Engineering, and the Mechanical Engineering Departments at Vanderbilt University. He received M.S. in Applied Mathematics, M.S. in Civil Engineering and Ph.D. in Civil Engineering at Rensselaer Polytechnic Institute. His research focuses on nonlinear response of heterogeneous materials and structures using computational modeling and simulation, including characterization of the failure response of systems that involve multiple temporal and spatial scales, and method development for failure analysis of composite systems subjected to impact, blast and other extreme loading and environmental conditions. Prof. Oskay is named Chancellor Faculty Fellow at Vanderbilt University in 2016 and Fellow of the American Society of Mechanical Engineers in 2017. Prof. Oskay also serves as the Associate Editor of the International Journal for Multiscale Computational Engineering.

Space Radiation Engineering
Robert Singleterry, Ph.D.
Research Engineer, NASA

12:00 - 1:00 P.M.
Friday, March 2
Engineering West Hall, Room W106

Space radiation is a broad subject. It include high energy nuclear physics, biology, and engineering. The engineering combines the knowledge gained in physics and biology to design and fly a spacecraft in the radiation fields of space. What are those fields? What is radiobiology tell us? How do materials react to these boundary conditions and end points? All of this leads to how we build a spacecraft to meet requirements of the mission and radiation protection. It’s not as simple as it seems!

Dr. Singleterry received his PhD, MS, and BS degrees in Nuclear Engineering with a PhD Minor in Mathematics from the University of Arizona in 1993, 1990, and 1984. He has worked at the E.I. Hatch Nuclear Power Plant from 84-85 as a Reactor Engineer, E.I. International from 85-89 as a Software Engineer, as a summer student at Argonne National Laboratory West from 89-93, and as a Staff Engineer at Argonne from 93-97. Since 1997, Dr. Singleterry has worked at the NASA Langley Research Center. He is now in the Durability, Damage Tolerance, and Reliability Branch working on space radiation engineering and related issues. He is currently leading innovative ways of computing faster, advanced transport methods, and interfaces from research codes to non-experts. Dr. Singleterry has received many awards for creativity and innovation and performance at NASA.

Jens Rosenberg, Ph.D.
The National High Magnetic Field Laboratory

Muon Detection for 4D Density Overburden Monitoring
Azaree Lintereur, Ph.D.
Assistant Professor, Penn State University

12:00 - 1:00 P.M.
Friday, February 16

Muon detection can be used to image the density of materials through which the muons have travelled. This includes any geological overburden above the detector. Overburden imaging is of interest for a variety of applications, such as monitoring CO2 sequestration reservoirs and tunnel detection. Both of these operations require the use of a detector that can be deployed below ground, which not only constrains the size of the system, but also necessitates a robust design. This talk will discuss the design and development of a detector that can be used to monitor the subsurface muon flux and produce images of the geological overburden.

Dr. Azaree Lintereur joined the Mechanical and Nuclear Engineering Department at Penn State University as an Assistant Professor in August 2017 and is establishing a detector development laboratory. Prior to joining Penn State University Dr. Lintereur was at the University of Utah, where she led the development of a radiation detection research program. She did a postdoc at Pacific Northwest National Laboratory where her research focused on 3He alternatives for neutron detection, and pulse shape discrimination methods for neutron-gamma ray sensitive materials. Her research interests include radiation detector development, nondestructive assay techniques, international safeguards, and 3He alternative technologies

Oil-Well Logging – Applications, Challenges, and Solutions
Weijun Guo, Ph.D.
Senior Technical Advisor, Halliburton

12:00 - 1:00 P.M.
Friday, February 9
Engineering East Hall, Room E3229

Oil-well logging is of critical importance for the oil and gas industry. Since the inception of the technology in early 1900s, both long-lasting and newly emerging application challenges have pushed the technology advance in both breadth and depth. The key problem to solve is to optimize hydrocarbon productions with finite amount of capital investment. Across the globe, five different strategic markets are the new norm of the industry. A bulk set of reservoir properties seem to remain to outsize the available logging technologies while we make day-to-day improvements to our portfolio with new ideas and younger physicists joining the industry. Nuclear logging is one of the five primary technologies, and contributes more than one third of the revenues. Statistical uncertainty is one of the most important aspects on nuclear logging. Through this talk, we will navigate through application examples on fundamental theories, challenges and solutions. What is on the horizon? This talk will be concluded in a brainstorming discussion.

Dr. Weijun Guo is a Sr. Technical Advisor for Halliburton. The primary responsibilities include leading LIFECYCLE® multi‐disciplinary projects for new drilling and logging tools and petrophysics software, and developing science competency. Prior to this assignment, he was the technical adviser on nuclear drilling and logging tools, including cased‐hole pulsed neutron tools and open‐hole neutron/density/gamma tools. His technical interest spans through drilling, formation evaluation, and reservoir surveillance applications. Dr. Guo has authored 42 technical papers, and invented 15 US patents. He serves as a technical reviewer for four key industry and academia journals, and is in the review panel for one US national lab project. Dr. Guo earned his Ph.D. in nuclear engineering from the North Carolina State University. He is a SPWLA member and serves in the SPWLA Technology Steering Committee.

Electrospinning: Past, Present and Future
H.Young Chung, Ph.D.
Visiting Scientist, University of Minnesota

12:00 - 1:00 P.M.
Friday, January 26
Engineering East Hall, Room E3229

Electrospinning has been a popular subject as a subspecies of nanotechnology since the publication of seminal Darrel Reneker paper in 1995. However, the history of electrospinning goes back to 1902 with two US patents. History of intervening years will be presented. We will review the history of interaction between aerosol science and electrospinning back to 1930s in Russia. Early paper on electrospinning in 1970s and patents on electrospinning in 1970 will also be shown. The industrial development of filtration products incorporating electrospun nanofibers from 1980s will be described.

The subject of electrospinning has drawn interests from both academia and industry. In academic research, electrospinning became popular because of the word ‘nano’ and ease of setting up experiments. On the other hand, electrospinning draw industrial interest largely due to commercial success of electrospun nanofibers in the air filtration market. The author has been involved in development of electrospinning at Donaldson Company since 1981 (before the publication of the first Reneker papers).

There are various potential applications of electrospinning in industry, for examples, filtration and separation, insulation, drug delivery, light management and cell culture in biotechnology. Only the air filtration application is proven successful commercially. It is partly due to the not-so-apparent collaboration between aerosol science and filtration. The collaboration between Particle Technology Laboratory at University of Minnesota and Donaldson Company will be discussed.

Electrospinning technology has been an essential tool for high efficiency air filtration. The future filtration requiring solutions of avoiding conundrum of smaller diameter-high pressure drop structure will be presented. New applications of elctrospun nanofiber structures will be also given.

Sama Bilbao Y León, Ph.D.
Associate Professor, Director of Nuclear Engineering Programs, Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University

Karla Mossi, Ph.D.
Associate Professor, Graduate Program Director, Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University