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Voiland College of Engineering and Architecture School of Mechanical and Materials Engineering

MME Seminar Series Welcomes Dr. Yogendra Joshi, Georgia Institute of Technology

Dr. Yogendra Joshi

G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology

Held in ETRL 101
Refreshments served in ETRL 119 at 10:30 am

Thermal Management and Design Approaches to

Enable Heterogeneous 3D Integration

Abstract

With the recent end of the International Technology Roadmap for Semiconductors, which has guided research on thermal packaging of microprocessors for nearly a quarter century, significantly different challenges are on the horizon.  Heterogeneous integration promises to bring in multiple functionalities in highly compact form factors via interposer based (2.5D) and three-dimensional (3D) stacked chip approaches.  Compared to planar integrated circuits (ICs), 3D stacked ICs as an emerging technology have significant advantages, including shorter interconnection length, smaller power consumption, and higher computation speed. However, chip stacking poses great challenges to thermal management.  Increased chip temperatures can degrade the reliability and performance, and increase the leakage power that constitutes a significant part of the total chip power. To mitigate these undesirable effects, advanced thermal management, such as microfluidic cooling can be employed. Very few experimental demonstrations of CMOS chips with integrated microfluidic cooling currently exist. In this presentation, inter-tier microfluidic cooling will be explored as a promising approach for future 3D stacked ICs due to its superior thermal performance and scalability. I will discuss ongoing research on microfluidic single phase and two phase cooling to address the high heat fluxes, and localized hot spots in these applications.  Examples of thermal/electrical co-design, which is essential for successful use of this technology will be presented for high performance and mobile applications. For the latter, thermal management and energy conservation must be simultaneously considered.  To fully utilize microfluidic cooling, reliable fluid delivery systems and good heat transfer fluids are required. It is concluded that extensive research on integration of inter-tier microfluidic cooling of 3D stacked ICs is still needed.

 

Biography

With the recent end of the International Technology Roadmap for Semiconductors, which has guided research on thermal packaging of microprocessors for nearly a quarter century, significantly different challenges are on the horizon.  Heterogeneous integration promises to bring in multiple functionalities in highly compact form factors via interposer based (2.5D) and three-dimensional (3D) stacked chip approaches.  Compared to planar integrated circuits (ICs), 3D stacked ICs as an emerging technology have significant advantages, including shorter interconnection length, smaller power consumption, and higher computation speed. However, chip stacking poses great challenges to thermal management.  Increased chip temperatures can degrade the reliability and performance, and increase the leakage power that constitutes a significant part of the total chip power. To mitigate these undesirable effects, advanced thermal management, such as microfluidic cooling can be employed. Very few experimental demonstrations of CMOS chips with integrated microfluidic cooling currently exist. In this presentation, inter-tier microfluidic cooling will be explored as a promising approach for future 3D stacked ICs due to its superior thermal performance and scalability. I will discuss ongoing research on microfluidic single phase and two phase cooling to address the high heat fluxes, and localized hot spots in these applications.  Examples of thermal/electrical co-design, which is essential for successful use of this technology will be presented for high performance and mobile applications. For the latter, thermal management and energy conservation must be simultaneously considered.  To fully utilize microfluidic cooling, reliable fluid delivery systems and good heat transfer fluids are required. It is concluded that extensive research on integration of inter-tier microfluidic cooling of 3D stacked ICs is still needed.

 

 

 

 

MME Seminar Series Welcomes: Dr. Tao Xing, University of Idaho

Held  in ETRL 101

Refreshments served in ETRL 119 at 10:30 am

Dr. Tao Xing, Ph.D., P.E.

Associate Professor, Department of Mechanical Engineering

University of Idaho, Moscow, Idaho

Solution Verification for Large Eddy Simulations
In Computational Fluid Dynamics

Abstract

With the dramatic growth of supercomputers, simulation based design, and ultimately virtual reality, have become increasingly important for the advancement of science and engineering.  Computational fluid dynamics (CFD) provides   computerized solutions for science and engineering problems using modeling, numerical methods, and high-performance computing. In CFD, the continuous partial differential equations are discretized into algebraic equations using numerical methods.  The algebraic equations are assembled and solved to get approximate solutions.  Thus, it is imperative to quantitatively estimate the numerical and modeling errors and associated uncertainties, which can only be achieved through rigorous verification and validation (V&V).  Additionally, guidelines for how to optimize a CFD simulation to obtain a minimum total simulation error are needed.  In this speech, definitions, general methodology and procedures of V&V will be covered. Based on statistical analysis, the “Factor of Safety” method shows advantages over various versions of the grid convergence index method, correction factor method, and least square method for Reynolds-averaged Navier-Stokes (RANS) V&V.  Nonetheless, these methods cannot be applied directly to large eddy simulations (LES) V&V.  Recently, a general framework for LES V&V was developed including a vast number methods based on two Hypotheses, ranging from a sophisticated seven-equation method to a simple single grid method. These methods were evaluated using implicitly filtered LES of periodic channel flows at friction Reynolds number of 395 on eight systematically refined grids. The seven-equation method shows that the coupling error based on Hypothesis I is much smaller as compared to the numerical and modeling errors and therefore can be neglected. The five-equation method based on Hypothesis II is recommended, which shows a monotonic convergence behavior of the predicted numerical benchmark (SC), and provides realistic error estimates without the need of fixing the orders of accuracy for either numerical or modeling errors. Based on the results from seven-equation and five-equation methods, less expensive three and four-equation methods for practical LES applications were derived. It was found that the new three-equation method is robust as it can be applied to any convergence types and reasonably predicts the error trends. It was also observed that the numerical and modeling errors usually have opposite signs in LES, which suggests error cancellation play an essential role in LES. When RANS verification method is applied, it shows significant error in the prediction of SC on coarse meshes. However, it predicts reasonable SC when the grids resolve at least 80% of the total turbulent kinetic energy.

Biography

Dr. Tao Xing earned his Ph.D. in Mechanical Engineering from Purdue University in 2002. He worked as a Postdoctoral    Fellow and Assistant Research Scientist at the Iowa Institute of Hydraulics Research from 2002 to 2008. He was an Assistant Professor from 2009 to 2016. Dr. Xing is currently an Associate Professor at University of Idaho. His research interests focus on both fundamental and applied CFD in multi-disciplines. Fundamental CFD research includes estimation of errors and uncertainties using quantitate solution verification and validation (V&V) method for turbulent flow simulations and entropy generation for bypass transitional boundary layers. For V&V, the “factor of safety method” he developed was evaluated as the most accurate and concise uncertainty estimates for monotonically converged numerical solutions.  He was invited to give 12 lectures including the keynote lecture on verification and validation in the 13th National Congress on Hydrodynamics in China in 2014. In 2015, he developed a general framework for V&V for large eddy simulations and very recently        five-equation and robust three-equation methods for LES V&V. Applied CFD research covers a broad range of disciplines including onshore and offshore wind turbine designs, vehicle aerodynamics, fluid-structure interaction for pulmonary ventilation, ship hydrodynamics, and desalination. Dr. Xing’s teaching interests focus on integration of simulation technology into engineering courses and laboratories, development of effective formative and summative evaluation   methods, and development of innovative teaching modules toward achieving ABET learning outcomes. His Google Scholar h-index and i10-index are 19 and 29, respectively. As a PI or Co-PI, he secured more than 1.8 million dollars funding since he joined the University of Idaho in 2011. He won the “Alumni Award” from the University of Idaho in 2013 and again in 2014. He won the “Outstanding Young Faculty Award” from College of Engineering in 2015. He is a licensed U.S. Professional  Engineer.

 

 

 

MME Seminar Series- Welcomes Dr. Charles Pezeshki, WSU Professor

Dr. Charles Pezeshki

Washington State University Professor, Director- Industrial Engagement

Seminar Starts at 11:00 am in ETRL 101

Refreshments served in ETRL 119 from 10:30 am to 11:00 am

Considering Research Ethics-

How do we develop our perception and truth in our results?
Abstract

Virtually all the graduate students and professors at WSU in engineering are involved in research efforts in one way or another. And while there is quite a bit of guidance on research process — we have internal reviews present in things like the IRB process, as well as conflicts of interest and their disclosure, for example — there’s very little on how we present new results, as well as the appropriate level to assert their truth

Biography

Dr. Pezeshki, or “Dr. Chuck” as he is known, will give a presentation on his work regarding the collective structure of knowledge that we create, as well as how human communities create knowledge, and the level of appropriate assertion of a given truth. Along the way, he’ll tour logical fallacies that the researcher should be aware of, as well giving some perspective on how we should pursue both reliability of results, as well as validity. He’ll end with two case studies, and their consequences, of what happens when researchers did not follow appropriate protocols, and will disclose the long-term consequences of those types of decisions, focusing on the use of sugar in the modern diet, and the Volkswagen emission scandal.

MME Seminar Series Welcomes Mr. Adnan Morshed, PhD Candidate, Washington State University

Mr. Adnan Morshed

PhD Candidate, School of Mechanical and Materials Engineering, Washington State University

Held in ETRL 101

Refreshments served in ETRL 119 at 10:30 am

Modeling of Biomechanical Systems in Microfluidic Device

Abstract

Electrodeformation of vesicles can be used as a useful tool to understand the characteristics of biological soft matter. Microfluidic devices are especially useful in this regard where the vesicles immersed in a fluid medium are subjected to an applied electric field. With minimal effort, a lot of intricate geometry can be imprinted in microfluidic chips which allows to observe the shift in vesicle deformation behavior. Modeling this kind of physical system requires consideration of both electric and hydrodynamic descriptions. The complex response of the vesicle membrane strongly depends on the conductivity of surrounding fluid, vesicle size and shape, and applied electric field. We studied the electrodeformation of vesicles immersed in a fluid media under a short DC electric pulse. An immersed interface method is used to solve the electric field over the domain with conductive or     non-conductive vesicles while an immersed boundary scheme is employed to solve fluid flow, fluid-solid interaction, membrane mechanics and vesicle movement. Force analysis on the membrane surface reveals almost linear relation with vesicle size, but highly nonlinear influence of applied field as well as the conductivity ratios inside and outside of the vesicle. Results also point towards an early linear deformation regime followed by an equilibrium stage for the membranes. Moreover, significant influence of the initial aspect ratio of the vesicle on the force distribution is observed across a range of conductivity ratios.

Biography

Adnan Morshed is in the third year of his PhD program at MME. His primary research interest is in the modeling of micro- and nanoscale biological phenomena. At present, his research is focused on the numerical exploration of experimentally hard to reach terrains in soft biological vesicles and studying key biophysical pathways in cancer propagation. He completed his B.Sc. and M.Sc. in mechanical engineering from Bangladesh University of Engineering and Technology (BUET).

Adnan enjoys computer programming and is fascinated with typography. He loves hiking and exploring the beautiful Northwest.

 

 

MME Seminar Series Welcomes Dr. Georges Ayoub, University of Michigan

Dr. Georges Ayoub

Assistant Professor, Industrial & Manufacturing Systems Engineering, University of  Michigan– Dearborn

Held in the  ETRL 101 Lecture Hall

Refreshments served in ETRL 119 at 10:30 am

Uncovering the deformation mechanisms in Ti/TiN multi layer under compressive, multi axial and nano-indention behavior with MD simulations

 

Abstract

The promising mechanical, physical and chemical properties of nano-scale metal/ceramic multilayers (MCMs) are of high interest for extreme environment applications. Understanding the plastic deformation mechanisms and the variables affecting those properties is therefore essential. The interface characteristics and the plastic deformation mechanisms under compressive, multiaxial and nano-indentation loadings in a Ti/TiN multilayer with a semi-coherent interface are numerically investigated. The interface structure of the Ti/TiN interface and the interface misfit dislocation were characterized using molecular dynamic simulations combined with atomically informed Frank-Bilby method. Three possible atomic stacking interface structures are identified according to the crystallographic analysis of the interface. Upon relaxation, large interface areas are occupied with the energetically stable configuration. Furthermore, the higher energy stacking are transformed into misfit dislocations or dislocation nodes. The Ti/TiN multilayer structure shows high strength and ductility under uniform compression loading. However, low strength and ductility are observed under tensile loading favored by crack initiation and propagation. Unlike typical metal stress-strain curves, metal/ceramic multilayers show two main yield points. Furthermore, the Ti/TiN multilayer structure shows three distinctive peak points for compressive loading normal and parallel to the interface. Furthermore, the misfit dislocation network at the Ti-TiN interface is found to dissociate to partials under driving force on the indenter tip and play an important role in the strengthening of Ti/TiN multilayers. We have observed several deformation mechanisms such as dislocation pile-up on the interface, and movement of misfit dislocations.

 

 Biography

Dr. Georges Ayoub completed his Ph.D at Lille University of science and technology in north France. Dr. Ayoub obtained his Master’s degree in 2007, also from Lille 1 University. Dr. Ayoub undergraduate work was completed at the Polytechnic Engineering School of the Lille 1 University (Polytech’Lille) in the field of mechanical engineering. Dr. Ayoub also obtained an Undergraduate Diploma in materials science at the University of Rennes 1 with highest distinction.

As a researcher, Dr. Ayoub started his career working in the capacity of a Post-doctoral Research Fellow at Texas A&M University at Qatar. He was promoted, in 2012 to Assistant Research Scientist and took leadership over 3 research projects in Qatar. Since then he has been able to establish his own independent research program and was awarded funding for 3 projects. Between August 2014 and August 2016 Dr. Ayoub worked as assistant professor at the American University of Beirut (AUB) and maintained an affiliation with Texas A&M University at Qatar as a Visiting Associate Research Scientist. Dr. Ayoub joined the University of Michigan Dearborn in September 2016, as assistant professor. His research projects involve experimental testing, characterizing and modeling the behavior of polymers and metal alloys. The research also entails developing algorithms and coupling them with finite element analysis to predict the material behavior under desired temperatures, deformation rates and loading conditions. Dr. Ayoub research has been published in more than 30 journal papers appearing in journals with high impact factors.

 

MME Seminar Series welcomes Dr. Behcet Acikmese, University of Washington

Dr. Behcet Acikmese

William E. Boeing Department of Aeronautics and Astronautics & Department of Electrical Engineering, University of Washington, Seattle

 

Held in ETRL 101

Refreshments served in ETRL 119 at 10:30 am

Everyone is encouraged to attend!

Real-time optimization for Guidance and Control of Autonomous Aerospace Vehicles

Abstract

Many future aerospace engineering applications will require dramatic increases in our existing autonomous control capabilities. These include robotic sample return missions to planets, comets, and asteroids, formation flying spacecraft applications, applications utilizing swarms of autonomous agents, unmanned aerial, ground, and underwater vehicles, and autonomous commercial robotic applications. A key control challenge for many autonomous systems is to achieve the performance goals safely with  minimal resource use in the presence of mission constraints and uncertainties. In principle these problems can be formulated and solved as optimization problems. The challenge is solving them reliably onboard the autonomous system in real time.

Our research has provided new analytical results that enabled the formulation of many autonomous control problems in a convex optimization framework, i.e., convexification of the control problem. The main mathematical theory used in achieving convexification is the duality theory of optimization. Duality theory manifests itself as Pontryagin’s Maximum Principle in infinite  dimensional optimization problems and as KKT conditions infinite dimensional parameter optimization problems. Both theories were instrumental in our developments. Our analytical framework also allowed the computation of the precise bounds of performance for a control system in term of constrained controllability/reachability sets. This proved to be an important step in rigorous V&V of the resulting control decision making algorithms.

This seminar introduces several real-world aerospace applications, where this approach provided dramatic performance improvements over the heritage technologies. An important application is the fuel optimal control for planetary soft landing, whose complete solution has been an open problem since the Apollo Moon landings of 1960s. We developed a novel “lossless convexification” method, which enables the next generation planetary missions, such as Mars robotic sample return and manned missions. Another application is in Markov chain synthesis with “safety” constraints, which enabled the development of new decentralized coordination and control methods for spacecraft swarms.

 

Biography

Behcet Acıkmese is a faculty in Department of Aeronautics and Astronautics and an adjunct faculty in Department of Electrical Engineering at University of Washington, Seattle. He received his Ph.D. in Aerospace Engineering from Purdue University. He was a senior technologist at JPL and a lecturer at Caltech. At JPL, He developed control algorithms for planetary landing, spacecraft formation flying, and asteroid and comet sample return missions. He developed the “flyaway” control algorithms in Mars Science Laboratory (MSL) mission, and the RCS algorithms for NASA SMAP mission. Dr. Acıkmese  invented a novel real-time convex optimization based planetary landing guidance algorithm (G-FOLD) that was flight tested by JPL, which is a first demonstration of a real-time optimization algorithm for rocket guidance. He is a recipient of NSF CAREER Award, several NASA Achievement awards for his contributions to NASA missions and new technology development. He is an Associate Fellow of AIAA, a Senior Member of IEEE, and an associate editor of IEEE Control System Magazine and AIAA JGCD.