Spring 2024 seminar

ABSTRACT

High-Temperature Gas-Cooled Reactors (HTGRs) play an important role in efforts to expand the nuclear power user energy domain from “just electricity production” to most of the industrial, transportation, and commercial energy consumption demand sectors.  Generation IV HTGRs are also attractive because of their inherent passively-safe characteristics—so much so—that some companies advertise their designs as “walk-away safe.”  Finally, some designers claim possible thermal cycle efficiencies ~50% higher than LWRs with lower electricity generation costs, a significantly reduced environmental impact, high proliferation resistance and superior radionuclide retention for long-term spent fuel disposal.  These “virtues” of the HTGR designs will be discussed in the context of HTGR research. 

BIO

Formerly the Principal Investigator responsible for definition and conduct of the experimental validation experiment program for the Next Generation Nuclear Plant and HTGRs based on NRC historically-accepted code adequacy guidelines at the Idaho National Laboratory. 

Position history:

·       Research Professor: Idaho State University, Dept of Nuclear Engineering—2014--Present

·       Professor of Practice: Texas A&M University, Dept of Nuclear Engineering—2012-2019

·       Distinguished Researcher: Idaho National Laboratory—1976-2014

·       Research Engineer:  General Electric Atomic Power Equipment Division

Education:  Ph.D. Nuclear Science & Engineering, Idaho State University, 2010; Mechanical Engr: B.Sc Univ of Florida, 1967; M.Sc. Rensselaer Polytechnic Institute, 1971

ABSTRACT

Extreme rainfall in the Indian summer monsoon can be destructive and deadly.  Although El Niño events in the equatorial Pacific make dry days and whole summers more likely throughout the subcontinent, their influence on daily extremes is not well established.  Using observational data spanning 1901-2020, we show that El Niño increases extreme daily rainfall likelihoods within monsoonal India (by 44\% at the 99.99th rain intensity percentile).  This uptick is concentrated in the summer's core rainy areas---the broad Central Monsoon Zone (+53\%) and the narrow Western Ghats southwestern coastal band (+70\%)---whereas extremes are broadly suppressed in the drier southeast and far northwest.  Except in the Western Ghats, all these signals appear driven by corresponding ones in extreme daily values of lower-free-tropospheric subsaturation; for the Ghats increases in right-tail subcloud undilute instability predominate.  This buoyancy-based framework for rainfall extremes could be extended to other monsoons, other variability modes, and to trends and projections of hourly and daily extremes under global warming throughout the tropics.

BIO

Spencer Hill is an Assistant Professor in the Department of Earth and Atmospheric Sciences at CCNY.  His research falls along two main tracks: (1) monsoon circulations and their rainfall, and (2) climate and weather impacts on New York City.  Hill got his B.S. from UCLA and his Ph.D. from Princeton.

ABSTRACT

Robotic manipulation has advanced numerous application domains such as home, manufacturing, warehouses, surgery, and space. Yet it is still challenging to perform complex and delicate manipulation tasks in an environment with uncertainty. In this talk, I will present our recent progress on three highly applied research projects that leverage robotic manipulation: (i) aquaculture, (ii) causality extraction, and (iii) minimally invasive surgery.

Aquaculture has been the fastest-growing source of animal protein. However, United States remains a relatively minor aquaculture producer. There is huge potential for offshore aquaculture. As part of a collaborative research project titled “Ocean-Powered Robots for Autonomous Offshore Aquaculture”, I will present our work on underwater free-floating manipulation using bio-inspired continuum arms.

Robotic manipulation in search-and-rescue missions is a promising force-multiplier in the future operations. Manipulating human beings in fast-changing and dynamic environments remains a challenging task due to the fact that (a) humans are highly deformable bodies, and (b) it is difficult to generate an accurate injury model of bodies as the result of physical Human-Robot-Interaction. I will present our work on the first step: a digital simulation framework for planning and controls of casualty extraction using a biomechanically accurate digital human model.

Surgical soft continuum robots allow for deep access to the anatomy while providing inherent safety. Real-time estimation of their shapes is crucial to ensure accurate task execution and to discern physical interactions between the robot and environments. I will present our work on model-based stochastic shape estimation framework for continuum robots.

BIO

Long Wang, who joined Stevens Institute of Technology in August 2019, is an assistant professor of mechanical engineering. His research interest lies in modeling, sensing, and control of robots, with a focus on building robots and intelligent machines to assist manipulation effort in challenging environments.The applications that Long is most interested in include robotic surgery and remotely operated manipulation tasks. These applications are embedded with research problems such as novel compliant robot mechanisms, advanced control algorithms for robot interactions with environments, and physical human-robot interactions. Long’s research is sponsored by USDA NIFA, NSF, and DHA.

ABSTRACT

With the development of functional materials and structural engineering, wearable electronics are transitioning from rigid gadget-based wearables to soft second-skin-like interfaces. In this seminar, I will present our efforts in applying functional materials and smart structures to achieve skin-like sensors and soft actuators. In specific, I will present our recent progress in skin-attachable sensors and skin-integrated haptic interfaces for human activity tracking and human-machine interactions. Our research aims to provide new solutions and explore new applications in personal healthcare, activity tracking, rehabilitation, soft robotics, and entertainment, through combined innovations in materials engineering, mechanical design, and multi-scale manufacturing and integration.

BIO

Dr. Shanshan Yao is an assistant professor in the Department of Mechanical Engineering at Stony Brook University. She received her B.S. and M.S. from Xi'an Jiaotong University. She received her Ph.D. degree in Mechanical Engineering from North Carolina State University in 2016. Before joining Stony Brook University, she was a postdoc at North Carolina State University from 2017 to 2019. Her research primarily lies in smart structures, wearable sensors, haptic interfaces, soft robotics, and integration techniques for wearable systems. Dr. Shanshan Yao was a recipient of the Faculty Early Career Development (CAREER) award from the National Science Foundation (NSF).

ABSTRACT

There is great interest in the automotive and aerospace industries to replace mechanical joints with adhesive joints because of their numerous advantages. In this study, we consider the static and dynamic (ballistic) performance of joints bonded with an ambient cure adhesive. The effects of primer and adhesive thickness are evaluated. First, the joints are subjected to static loads to determine their strength. The results are compared with those obtained for previously studied adhesives. A finite element model is developed to simulate the experimental results. Next, the bonded joints are subjected to ballistic impact loads, and the critical failure speeds are determined. The results are again compared with those obtained for previously studied adhesives. A finite element model is developed, and the energy absorbed by the adhesive is calculated. It was observed that the ambient cure adhesive under dynamic loads may absorb more energy than other adhesives studied previously. 

BIO

Yesim Kokner is a Ph.D. student in the Department of Mechanical Engineering at CCNY. She received her bachelor's degree in 2017 from Kocaeli University (Turkey), and her Master’s degree from CCNY in 2022. She passed the qualifying exam in Aug 2023 and is currently working on her thesis in the area of bonded structural patch repairs under fatigue load. Her research interests encompass adhesively bonded multi-material joints, 3D-printed carbon-reinforced materials, and composites. Her academic contributions include presentations and publications at conferences.

Gizem Derya Demir is a Ph.D. candidate in the Department of Mechanical Engineering at CCNY. She graduated from MEF University (Istanbul, Turkey) in 2020. She joined the PhD program at CCNY in August 2020. She passed the qualifying exam in August 2021 and the 2nd exam in November 2023. Currently, she is working on adhesively bonded multi-material joints including 3D-printed metals subjected to static and dynamic loads . Her research interests include adhesively bonded joints, 3D-printed metals, and composites. She has presented and published her research results at conferences.

ABSTRACT

Reacting/high-speed flow investigation with non-intrusive optical techniques permits researchers to probe fluid flows in harsh or otherwise previously inaccessible environments. New insight into the flow physics of the problems in supersonic and hypersonic flows can be had with the clever application of recent advances in laser, camera, and electronics technologies. In this talk, two examples of such efforts will be discussed. First, new data on hypersonic turbulence with tagging velocimetry will be presented. Then, new drop aerobreakup and impact data pertaining to the multiphase flow in high-speed-vehicle/weather interactions will be presented. 

BIO

Nick’s current research interests include high-speed and reacting flows, chemical-thermodynamics, and heat transfer with applications in the fields of defense and energy/sustainability. Current projects include novel methods of high-speed flow velocimetry, hypersonic boundary-layer instability, shock-wave/boundary-layer interaction, multiphase flows, biomass to bio-oil conversion, and nitrogen-based fuels research. Nick received his BS in Mechanical Engineering from SUNY Binghamton in 2008, then received his MS and PhD degrees in 2009 and 2013 from the Caltech Graduate Aerospace Laboratories (GALCIT). In 2013, he was a PostDoc at Caltech and then a Visiting Assistant Professor at Stevens in the Mechanical Engineering Department at Stevens Institute of Technology in Hoboken, New Jersey. Nick was an Assistant Professor (2014-2020) and is currently an Associate Professor (2020-present). Nick spent four summers, from 2014-2017, as an Air Force Summer Faculty Fellow at AEDC White Oak in Silver Spring, MD.

ABSTRACT

Particle suspensions can fracture into intricate patterns as they are pushed out of equilibrium. We probe the fracture and relaxation characteristics of a dense aqueous cornstarch suspension that exhibits discontinuous shear-thickening behavior. Air injection into three-dimensional bulk suspensions can lead to smooth bubbles that rise upwards under the action of buoyancy or to sharp cracks that remain attached to the injection nozzle. We link the shape and the relaxation dynamics of the air cavity to the cornstarch rheology. In a second example, we report the crack dynamics and morphology occurring as drops of aqueous nanoparticle suspensions evaporate on a glass surface and leave behind a solid particle deposit. We show that in the final stage of drying, the stresses in the deposit can be released in two distinct ways: by bending out of plane or by forming a second generation of cracks.

BIO

Irmgard Bischofberger is an experimentalist working in the fields of fluid dynamics and soft condensed matter. She obtained her Ph.D. degree in Physics from the University of Fribourg and has been a postdoctoral fellow in the Physics Department at the University of Chicago. She is an associate professor in the Department of Mechanical Engineering at MIT. Her research interests include the spontaneous pattern formation from fluid instabilities and drying processes and non-equilibrium phenomena in soft gels. Irmgard is passionate about communicating science to a diverse audience and has a longstanding ‘Science and Arts’ collaboration with artists and musicians.

ABSTRACT

The talk will aim to highlight several areas of our research that includes but are not limited to fabrication of nanoscaffold for tissue engineering, development of unique graphene and graphene quantum dots surfaces, biomimetic structures, and engineered brain organoids. We seek to understand the fundamental science process at the interface of engineering and bioscience to come up with biomedical engineering applications.  We will present how nano-scale structures are excellent for useful tissue engineering systems. We will also show the design of graded graphene quantum dots that essentially are instructional surfaces to control DNA attachment. A very early report on vascularized brain organoids structures that may have significant implications toward human cognition will be presented. Some simple but very effective approach on forming 3 D graphene solids for future biomedical devices will be discussed. I will also discuss some of our computational biology/bioinformatics work that complements the experiments.

BIO

Dr. Prabir Patra is an experimentalist working in the fields of Nanobiomaterials and their applications in biomedical engineering and materials science. He obtained his Ph.D. degree in Materials Science from IIT Kharagpur and has been a postdoctoral fellow in the Bioengineering Department at the University of Massachusetts Dartmouth and in the Department Materials Science and Nano Engineering (formerly known as Mechanical engineering and Materials Science) at Rice University. He is Jerome A Gilbert Chair professor and the Chair of the Department of Biomedical Engineering at Marshall University. His research interests include the electrospinning and bioprinting of soft structures and studying structure and properties of materials at a nanoscale to effectively use them in tissue engineering. Prabir is passionate about communicating science to a diverse audience at the intersection between engineering, medicine, and biology.

ABSTRACT

New system-level codes are being developed for advanced reactors for safety analysis and licensing purposes. Thermal-hydraulics of advanced reactors is a challenging problem due to complex flow scenarios assisted by free jets and stratified flows that lead to turbulent mixing. For these reasons, the 0D or 1D models used for reactor plena in traditional safety analysis codes like RELAP cannot capture the physics accurately and introduce a large degree of modeling uncertainty. System-level calculation codes based on the advection-diffusion equation neglect turbulent fluctuations. These fluctuations are extremely important as they introduce higher-order moments, which are responsible for vortex stretching and the passage of energy to smaller scales. Komolgorov hypothesized that the flow velocity field follows a -5/3 scaling in the inertial region where Markovian characteristics can be invoked to model the interaction between eddies of adjacent sizes. This law holds true in the inertial region where the flow is Markovian. For scalar turbulence, the scaling laws are affected by thermal diffusion. If a fluid has a Prandtl number close to one, the thermal behavior is dominated by momentum, so the spectra for velocity and temperature are similar. For small Prandtl number fluids, such as liquid metals, the thermal diffusion dominates the lower scales and the slope of the spectrum shifts from the -5/3 slope to a -3 slope, also called the Batchelor region. System-level thermal hydraulics codes need to be able to capture these behaviors for a range of Prandtl number fluids.

Direct numerical simulations (DNS) are capable of capturing these scale interactions in scalar turbulence, but are computationally expensive for simple geometries and impossible at the system level. An alternative way to model the turbulent fluctuations can be described through a reduced-order model using the principles of statistical mechanics. Statistical mechanics-based methods provide a method for extracting statistics from data and modeling that data using easily represented differential equations. The Kramers-Moyal (KM) expansion method can be used either as a subgrid-scale (SGS) closure for solving the momentum equation or to model velocity and temperature fluctuations directly. This method can be used as a statistical surrogate for use in large-scale systems that captures the scale interactions accurately while being computationally efficient. 

BIO

Molly Ross is a thermofluidic system engineer at Oak Ridge National Laboratory. She obtained her bachelor’s degree in mechanical engineering from Kansas State University in 2017, and will obtain her PhD in nuclear engineering from Purdue University in May, 2024. Her primary research area focuses on developing stochastic closures to turbulent flows and heat transfer models with specific applications in thermal-hydraulic safety analysis. She has also investigated other keynote issues in nuclear engineering. This has included developing a neutron radiography system to provide high resolution void fraction measurements to investigate debris bed coolability as well as developing machine learning algorithms to predict and classify material thermal properties. In her future research career, she plans to extend both stochastic methods and machine learning algorithms to characterize physics in advanced reactors, improve grid-scale planning, and provide a framework to allow better-informed decision making from available sensor information.