Spencer Quiel is an Assistant Professor in the Department of Civil and Environmental Engineering at Lehigh University. His research focuses on resistance to extreme loads.
In recent years, blast hazards due to acts terrorism have resulted in significant damage to several structures, including the Murrah Federal Building in Oklahoma City in 1995 and the Khobar Towers in 1996. Accidental blasts, such as a 2011 gas utility explosion in Allentown, PA, have also caused significant damage to neighboring buildings and other infrastructure. Though relatively infrequent, blast hazards can cause extensive amounts of property damage and, more importantly, loss of human life. The design of structures to resist the effects of blast due to an explosive detonation is performed using a variety of analysis tools to simulate dynamic structural response to a blast-induced shock wave. The most common method in the current state-of-practice is the Single-Degree-of-Freedom (SDOF) method, which has also been used to model structural response to other dynamic loading such as earthquake-induced vibration. An SDOF system is a mathematical model in which a structural element is collectively represented as a single mass, spring, and damper to which a force time history is applied. A representative SDOF model for a blast-loaded column is shown below.
For blast threats at large standoff distances, previous experimental and computational studies have shown that the static bending shape assumption used by SDOF analysis is reasonable. However, experimental data and advanced analysis tools have shown that the SDOF method has difficulty in accurately capturing blast effects that are close range but not close enough to cause breach (or “punching”) damage. These “intermediate” range blast threats constitute a significant portion of the design-basis threats that are considered in current practice, and therefore the applicability of SDOF analysis for these cases is of great interest to the industry.
Paolo Bocchini is a an Assistant Professor of Structural Engineering at Lehigh University and Javier Buceta is an Associate Professor of Chemical Engineering at Lehigh University. Their research synergy, together with Graziano Fiorillo, a Postdocoral Research Associate in Dr. Bocchini’s and Dr. Buceta’s labs, led them to begin developing models for predicting ebola outbreaks.
What is the chance that two structural engineers and a physicist team up to fight one of the deadliest diseases in the history of humankind? Well, it looks like the plot of a Dan Brown novel, but it really happened, and it all started literally by “chance”, probability.
In 2014 a group of us, Lehigh University faculty, noticed that our university has a high density of researchers interested in Probabilistic Modeling and its applications to engineering and science, spread across various departments and colleges. For this reason, we decided to start coordinating our graduate courses to create a better synergy. But you know how it works: if you put two or more professors in the same room, they start talking about their research. So, at some point, Javier described his innovative way to model the non-homogeneous migration of bats infected by Ebola, which seems to be the main mechanism in which the virus travels for hundreds of miles triggering outbreaks in cities that did not see it coming and are completely unprepared for it, with devastating effects. Then Paolo noticed that the mathematical formulation and the type of uncertainties in the model that Javier used for infected bat migration have strong similarities with the way in which he addresses the uncertain propagation of seismic waves over a large region. It was (scientific) love at first sight. Paolo and Javier immediately saw the potential of combining Paolo’s novel hazard models and the rigorous framework that civil engineers use for catastrophe modeling, with the cutting-edge technique that Javier was developing to capture the disease spreading. The outcome is a comprehensive tool that can predict (in a probabilistic sense) the risk of Ebola outbreaks over a region as broad as the entire African continent and, in this way, drive preemptive allocation of limited resources in the most effective way, to fight promptly outbreaks if they happen to occur.
With this idea, we (Paolo and Javier) submitted a Collaborative Research (CORE) proposal that was funded (thank you Lehigh!) and allowed us to hire a postdoc and bootstrap this new line of research. As you may imagine, it wasn’t easy to find a person with the right competences and enough curiosity to join us in this adventure at the boundary of several disciplines. Luckily, we found Graziano, who with his expertise in probabilistic modeling applied to engineering problems and his proficiency with high-performance computing has been the perfect scholar to carry on this project. With enthusiasm, our “bold trio” started working against Ebola in early 2016 (some people make fun of us saying that we are rather a “bald trio”).
Nik Nikolov is an Assistant Professor of Art, Architecture and Design at Lehigh University.
This research project investigated the problems, workflow, and feasibility of designing a small topologically optimized structure and its fabrication in polymer-extruding large area 3d printer. Topology optimization (TO) as an architectural design tool is largely unexplored, in contrast to its wide use in the field of mechanical engineering. As big area additive manufacturing (BAAM) finally enters the realm of full-scale single-build structural design, research like the one proposed holds a significant potential for design innovation in addressing structural expression in buildings of varying scales.
The work was presented at the ACSA Fall Conference: Between the Autonomous & Contingent Object, October 8-10, 2015 at Syracuse University, Syracuse, NY and was accepted for journal publication and presentation at the 2016 International Conference on Structures and Architecture June 19-21, Guimaraes, Portugal. Additionally the work was part of a NSF grant application (Directorate of Engineering, PD 15-1637, proposal title “Development of Binder Jet 3D Printing of Concrete Components for Structural and Architectural Applications”) with prof Clay Naito, co PI.
Justin Jaworski and Keith Moored are Co-PIs and both Assistant Professors of Mechanical Engineering and Mechanics at Lehigh University. They were assisted by graduate student Nathan Wagenhoffer. Below they discusses their research on how noise is created.
Aerodynamic noise generation is important to many engineering applications, such as wind turbines and aircraft, where noise annoyance to the public is critical. Excessive noise explains in part why most airports are located well outside of city limits and major highways are flanked by traffic noise barriers; people don’t like noise. The generation of noise is found by analyzing how the air or fluid around objects is disturbed. For our purposes, we identify noise generation in two broad senses: scattered noise and radiated noise. Scattered noise results from a sound wave encounters a solid body and is amplified and bounces off. Radiated noise is made by vibratory motion of the body. If we can find a way to model acoustic disturbances in air, for example, then we can find how these motions can generate noise. In a concerted effort to identify the noise from arbitrary solid bodies, we have developed a two-dimensional (2D) acoustic field solver. The 2D model allows us to simplify problems to their essentials, while still ascertaining where and how the noise is generated for a specific body. We simply need to define how does the pressure around a body behaves and then a resulting acoustic field can be found.
But finding the pressure field around an airfoil, for instance, is not a straightforward task. To accurately find the pressure on a moving airfoil, one actually has to solve the equations of fluid flow for the body. We choose to describe our fluids problem with the similar mathematical treatment as the acoustics section. This allows for us to use the same to perform the analysis on the exact same geometry and exploit any speed up algorithms on both problems. The fluid solver finds how the airfoil makes vorticity, or local spinning of a region of fluid, due to its movement. Vorticity is responsible for most sound generated created at low speeds, so a coupling of this flow solver with the acoustic solver is natural. The motion of a vortex, a coherent region of vorticity, produces a greater pressure than its surrounding area.
Continue reading Using computation to understand noise production and reduction
All stars are not created equal. When you look out into the night sky, you are seeing all sorts of unique and interesting objects. Some stars are small and cool (at least, compared to our Sun), and live for many billions of years. Others have evolved and inflated to enormous sizes- even over 1,000 times the size of our sun. There is a class of bright, blue stars called “Classical Be stars” that are between about 5 – 20 times more massive than the sun, and spin so quickly that they are nearly torn apart by the resulting centrifugal force. These stars also have disks that grow and shrink, appear and disappear. Classical Be stars are unique in astronomy, because their disks originate from the stars themselves. Material from the surface of the star is flung outward with so much speed (and angular momentum) that it is launched into orbit, and then settles into a disk in an event called an “outburst”. Lehigh physics professor Joshua Pepper and graduate student Jonathan Labadie-Bartz are studying these objects because there is still much that is unknown, especially regarding the physical mechanisms behind outbursts. The header image shows an artist’s rendition of a Be star and its disk.
John Spletzer is an Associate Professor of Computer Science and Engineering at Lehigh University. Below he details the
The inspiration for this project came during my sabbatical at Love Park Robotics, LLC (LPR) in 2015. LPR is a robotics startup doing work in industrial perception, and the primary project I worked on was a vision-based pallet detection system for use by Automated Guided Vehicles (AGVs). AGVs are autonomous vehicles operating in warehouse environments. Think “robot forklift,” and you have the right idea. To estimate their position and orientation, AGVs typically rely upon 2D LIDAR (laser scanner) based localization systems that track reflector targets surveyed into the warehouse. The approach is very effective, and can provide sub-centimeter levels of accuracy. However, the process of installing the targets is both time consuming and expensive. Furthermore, it needs to be repeated any time the warehouse is reconfigured. Conversations with Tom Panzarella, CEO of LPR, lead us to investigate an alternative approach. Our hypothesis was that recent advances in 3D LIDAR systems would allow us to estimate AGV pose by tracking natural features already existing in the warehouse. This would eliminate the need for retroreflector targets all together. We refer to this technology as AGV-3D. From my NSF CAREER research, my lab had already demonstrated that a smart wheelchair system using a similar approach could reliably navigate in an urban environment without GPS. You can see an early video from the project here:
Jill McDermott is an Assistant Professor in the Department of Earth and Environmental Sciences at Lehigh University. Her research is taking her to the high Arctic to explore for new volcanic activity and ecosystems on the seafloor. Follow along live on the cruise blog.
NASA’s mission to the ice-covered ocean of Jupiter’s moon Europa will launch in the 2020s. About a decade from today the first data return may arrive, but in the meantime there is plenty to do on our own planet. This week, I join a rare mission on the German icebreaker Polarstern to do the next best thing – a search for submarine hydrothermal vents in the Arctic Ocean. Our goal is to reveal the chemical signatures that accompany life on the seafloor, and track these signals upward through the ocean water to the overlying ice-water interface, and into the ice itself. The idea is to discover an extreme ecosystem living below the Arctic ice to understand how to design a mission for a future space lander. This well-informed lander will make similar measurements while looking for life on Europa’s icy surface.
At 87°N 61°E in the Arctic, two of Earth’s tectonic plates diverge along an underwater volcanic mountain chain called the Gakkel Ridge, which stretches for 1,100 miles off Greenland towards Siberia. The plate motion here is the slowest in the world, spreading apart only 0.4 inches per year, at a rate 3 times slower than your fingernails grow. Due to this low tectonic activity, it seemed unlikely that the Gakkel would host hydrothermal vents – places where seawater circulating through fractures in the seafloor rock extracts heat derived from volcanic activity, and rises up to the seafloor in scalding plumes of mineral-laden water. These vents deliver chemicals to the seafloor that provide energy and building materials for specialized ecosystems, a process called ‘chemosynthesis.’ In 2003, however, a team of shocked scientists discovered chemical signatures in the water indicating multiple regions of hydrothermal activity along the Gakkel Ridge.
All scientific research requires patient dedication, and this expedition builds on years of risks, set-backs, and successes of many colleagues. The deep ocean is harsh. The freezing waters of the Arctic are even less forgiving than the mid-latitudes, and little is known about the seafloor ecosystems that are living there, undetected for tens of millions of years. In the coming weeks, I may be among the fortunate few to collect the first samples at the seafloor at one of the Gakkel vent sites.
We are aiming for a particular location in the Arctic, the Karasik Massif, an underwater mountain that rises rapidly from 15,400 feet depth to 1,850 feet depth. The Karasik Massif lies along a fault, a break in the seafloor rock that cuts through thin ocean crust into underlying ‘ultramafic’ rocks that formed deeper in Earth’s mantle.
The ultramafic geologic setting makes this site an exciting target for exploration due to the geochemistry that arises when circulating fluids interact with iron-rich rocks at high temperatures and pressures. Similar conditions exist at two other known hydrothermal fields in the Atlantic Ocean, Lost City and Rainbow, where vent fluids expelled at the seafloor are rich in dissolved hydrogen gas. The enrichment in hydrogen gas means there is great potential for the chemical, or ‘abiotic’ formation of organic molecules like methane and formic acid – possible precursors to the prebiotic compounds from which life on Earth emerged. There are only a few well-characterized seafloor ultramafic vent sites, however, and every one is different. This expedition is vital to understand the full range of chemical and biological diversity possible around Earth’s chemosynthetic ecosystems.
One challenge to studying the chemistry of modern vent fluids is that living things now permeate our planet. Organic compounds can also be generated and consumed by life itself, of course, and active microbial communities living in the seafloor around the vents rely on chemical energy from compounds emitted by the vents, such as hydrogen and methane. My goal on this expedition is to collect vent fluids and characterize their geochemistry, including distinguishing abiotic from biotic chemical processes, and how these influence the generation of life-related biogeochemical signatures.
To collect the vent fluids, we will launch the Nereid Under-Ice, a new remotely operated underwater vehicle developed and operated by the Woods Hole Oceanographic Institution . The Nereid UI will first be deployed in free-swimming autonomous mode to make high-resolution seafloor maps and track down the vents by measuring chemical clues, such as particle-rich water and locations where the seawater is relatively rich in hydrogen and methane. Once the exact location of the vent site is known, the Nereid UI will transform and launch again, now tethered by a fiberoptic cable the width of a human hair. I will equip it with titantium syringes that can collect vent fluid samples and maintain seafloor pressures until the samples are back onboard the ship. There my colleagues and I will begin the exciting task of understanding the origin of these fluids, how they sustain life on the Arctic seafloor, and what this means for life detection on other planetary bodies in our solar system and beyond.
Research support includes funding from the National Aeoronautics and Space Administration and the Alfred-Wegener Institute.
Research icebreaker Polarstern: Mario Hoppmann, Alfred Wegener Institute
Mosaic of the Lost City Hydrothermal Field: D. Kelley, University of Washington
Nereid Under-Ice rendering: Woods Hole Oceanographic Institution
Kathy Iovine, an Associate Professor in the Department of Biological Sciences, and Bob Skibbens, a Professor in the Department of Biological Sciences, introduce you to their research on Roberts Syndrome. This work is funded in part by a Faculty Innovation Grant.
Greetings! The purpose of this post is to introduce you to a Faculty Innovation Grant titled Developing a vertebrate model system for Roberts Syndrome. Roberts Syndrome (RBS) is a severe form of birth defects that significantly impacts bone growth (as well as cognition and organ development). In RBS patients, the long bones of the limbs are severely reduced, along with craniofacial abnormalities (cleft palatte, small head size, etc). The syndrome arises due to mutations in a gene named ESCO2, but the basis of the ESCO2 defect remains unknown. An important step forward will be to develop a model system for RBS so that we can ultimately devise clinical therapies.
As part of a collaboration between the Skibbens and Iovine lab groups, we are establishing the zebrafish fin as an RBS model system. Zebrafish fins are an excellent system since amputation results in complete regrowth, and we have the technology to turn down gene function during regrowth (“regeneration”). We found that loss of Esco2 protein causes skeletal defects in the zebrafish regenerating fin (Figure 1 shows a normal fin skeleton). With the ability to assay for Esco2 function in regenerating fins, we are pursuing a new model that Esco2 may cause skeletal defects by regulating the expression of genes. Evidence obtained through this collaboration suggests that Esco2 regulates cs43 – a gene that encodes a protein previously shown by the Iovine lab to impact bone growth (check out Iovine et al., 2005, Developmental Biology) and implicated in a developmental abnormality referred to as Oculodentodigital dysplasia. This research has been published in the journal Developmental Dynamics (Banerji et al., 2016 Developmental Dynamics)!
More recent efforts have been to provide mechanistic insights into how Esco2 regulates the expression of the skeletal gene cx43. The most direct way to show this is to demonstrate that the Esco2 protein, or a protein regulated by the function of Esco2 (i.e. Smc3), associates with the cx43 gene. Esco2 regulates the ability of Smc3 (and others) to associate with DNA. We are now testing if Smc3 physically binds to the DNA surrounging the cx43 gene. Raj Banerji has made important progress showing that she can isolate chromatin (i.e. genomic DNA plus all of the associated proteins) from a fin cell line, AB9. She can also isolate only the parts of the chromatin that are associated with Smc3. She is now testing if cx43 DNA is among the isolated Smc3-bound chromatin.
Keywords: skeletal disease, zebrafish, regeneration, gene expression