Penn Engineering Events

ASSET Seminar: Using Large Language Models to Build Explainable Classifiers, Chris Callison-Burch (University of Pennsylvania)
2023-02-08 12:00 - 13:30 (America/New_York) | Levine 307, 3330 Walnut Street, Philadelphia, PA, 19104, United States
ABSTRACT:
I’ll present research on using large language models (LLMs) to build explainable classifiers. I will show off work from my PhD students and collaborators on several recent research directions:

Image classification with explainable features (https://arxiv.org/abs/2211.11158)
Text classification with explainable features (work in progress)
The importance of faithfulness in explanations (https://arxiv.org/abs/2209.11326)
(Time permitting) A faithful “chain of thought” LLM reasoner that produces code in its explanations (https://arxiv.org/abs/2301.13379)

Here’s an example of the automatically generated concepts that we use for image classification in the first
The papers that I’ll present are joint work with:
Adam Stein, Ajay Patel, Ansh Kothary, Artemis Panagopoulou, Daniel Jin, Delip Rao, Eric Wong, Harry Li Zhang, Kathleen McKeown, Marianna Apidianaki, Mark Yatskar, Shenghao Zhou, Shreya Havaldar, Veronica Qing Lyu, Yue Yang, and othe

Spring 2023 GRASP Seminar: Henry Fuchs, UNC Chapel Hill, "Augmented Reality Glasses: a 50-year Adventure"
2023-02-07 15:00 - 16:00 | Raisler Lounge (Room 225), Towne Building, 220 South 33rd Street, Philadelphia, PA, 19104, United States
This is an in-person only event with attendance in Raisler Lounge (Towne 225). The presenter will be in-person as well.
ABSTRACT
Many of us foresee of a future in which AR eyeglasses are worn all day, replacing of our current prescription eyewear. That future may not arrive for a while and predicting its benefits and problems may be as premature as early predictions about the use of mobile phones or about “a helicopter in every garage.” Nevertheless, a few sample applications seem both obvious and promising, 1) continuous physiological monitoring for sudden and long-term health changes, and 2) virtually embodied avatars for guidance in navigation, exercise, and training. I will also talk about the rocky history of head-worn AR systems, which in contrast to the amazing, continuous advances in Integrated Circuit fabrication technology, has gone through multiple bust and boom cycles. I will talk about a few of the historic obstacles and how some were overcome and others side-stepped. I will summarize a few of the remaining problems, possible paths to their solution, and describe several of our projects in these areas.

MEAM Seminar: "Designing Interfacial Phenomena for Water, Energy, and Sustainability"
2023-02-07 10:00 - 11:30 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Solid/water interfacial phenomena are pervasive in both natural and built environments. Heat exchangers, membrane pores, and packed bed reactors are all examples of solid/water interfaces where interfacial phenomena and small-scale fluid physics can have outsized influences on process efficacy and sustainability. Even innocuous surfaces such as reactor walls are not inert and can actively interact with aqueous solutions and thereby create inefficiencies. Surface properties are crucial in controlling and reducing such inefficiencies. New tools and techniques in the fields of micro/nano-fabrication, thin film deposition, and soft matter physics have enabled unprecedented capability to manufacture engineered interfaces. By precisely designing the composition, chemistry, and microscopic geometry of interfaces, it is possible to go beyond simply selecting the best available material for a given application. Instead, we can specifically design surfaces and processes for fine-tuned control over interfacial phenomena to achieve drastic reduction, or even complete elimination, of inefficiencies. Here, three examples in which interfacial engineering can enable new paradigms for water, energy, and sustainability will be presented. I will show that composite liquid/solid surface can eliminate mineral fouling for improved material resilience, that nano-engineered materials can induce ejection of foulant crystals with potential application for heat transfer and waste brine management, and that multiphase microfluidics with controlled pore geometries can enable new separation processes.

P.E.S.T.L.E. Orientation - February 3
2023-02-03 16:00 - 17:00 | https://upenn.zoom.us/j/96715197752
Join P.E.S.T.L.E. for our Zoom Orientation session on Friday, February 3 at 4:00 pm! Please email us at pestle@seas.upenn.edu if you have any questions.

Spring 2023 GRASP Seminar: GRASP Panel on Future Challenges and Big Problems
2023-02-03 10:30 - 11:45 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
This is a hybrid event with in-person attendance in Wu and Chen and virtual attendance via Zoom. This week’s panelists will be in-person as well.
PANEL DISCUSSION
Please join us for a lively panel discussion featuring GRASP Faculty members including Dr. Nadia Figueroa, Dr. Dinesh Jayaraman, and Dr. Marc Miskin. This panel will be moderated by Penn Engineering SEAS Dean Dr. Vijay Kumar.

CIS Seminar: "Proofs, Cryptography and Quantum Information"
2023-02-02 15:30 - 16:30 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Many cryptographic protocols will be rendered insecure if sufficiently powerful quantum computers are built. While this remains at least a few decades away, there is another, more immediate, problem: many widely-used security analysis techniques rely on properties of classical information that do not hold in the quantum setting, rendering the security of many schemes unclear even against today’s quantum computers. In this talk I will present techniques I have developed to address both of these challenges.

MSE Seminar: "Metamaterials: From Invisibility Cloak to Future Extended Reality Displays"
2023-02-02 10:30 - 11:30 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
The invisibility cloak in Harry Potter and the dreams of invisibility as a superpower are no longer fiction. With the invention of metamaterials, they are theoretically and experimentally possible in real life. Metamaterials — materials that are engineered to have properties that are not found in naturally-occuring materials — allow us to overcome physical limitations. Scientists around the world are researching metamaterials that can be used in diverse sectors, including healthcare, optical display, and military affairs. For example, metalenses, which can exceed the physical limitations of light, may facilitate leaps in biology and chemistry. The development of metamaterials has just begun, but their potential is limitless. In this talk, I will give a brief overview of metamaterials and metasurfaces: principles, applications and manufacturing methods towards their science-to-technology transition.

BE/Genetics Seminar: “A network-based blueprint for understanding condensates in health and disease” (David W. Sanders, Princeton University)
2023-02-01 13:00 - 14:00 | https://upenn.zoom.us/j/96715197752
PENN GENETICS SPECIAL SEMINAR | David Sanders, PhD
“A network-based blueprint for understanding condensates in health and disease”

David W Sanders, PhD
Postdoctoral Fellow
Chemical and Biological Engineering
Princeton University

Zoom Link
Contact Info:
For more information, please contact Sadie Robinson at sarahjr@upenn.edu
This is a joint seminar between the Departments of Genetics and Bioengineering

ASSET Seminar: The marriage of logic and learning: will it be a happily ever after?, Jyotirmoy Deshmukh (University of Southern California)
2023-02-01 12:00 - 13:30 | Levine 307, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Presentation Abstract:
Huge strides have made in the widespread adoption of autonomous and human-in-the-loop cyber-physical systems (CPS), partly fueled by dramatic improvements in learning-based techniques. An important aspect of such CPS applications is that they are safety-critical: any undesirable behavior by such systems can cause serious harm to human lives or property. The formal methods community has been an advocate of using logic and automata as specifications for safety-critical CPSs, and the past few decades have seen significant strides in algorithms for their verification, testing, and automated synthesis. A new challenge now is the presence of learning-enabled components (LECs) in CPSs, and in this talk, we will review some recent work on using logic and learning-based techniques to provide guarantees for CPS applications using LECs. The happiness of this marriage between logic and learning depends on the applicability and scalability of these techniques to real-world systems; we will discuss success stories as well as challenges that need to be solved.

MEAM Seminar: "3D Printing Active Electronic Devices"
2023-01-31 10:00 - 11:30 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
The ability to three-dimensionally pattern semiconducting electronic and optoelectronic materials could provide a transformative approach to creating active electronic devices without the need for a cleanroom or conventional microfabrication facilities. This could enable the generation of active electronics on-the-fly, using only source inks and a portable 3D printer to realize electronics anywhere, anytime, including directly on the body. Indeed, interfacing active devices with biology in 3D could impact a variety of fields, including biomedical devices, wearable electronics, bioelectronics, smart prosthetics, and human-machine interfaces. Developing the ability to 3D print various classes of materials possessing distinct properties will enable the freeform generation of active electronics in unique functional, interwoven architectures. Yet, achieving seamless integration of these diverse materials via 3D printing is a significant challenge which requires overcoming discrepancies in material properties in addition to ensuring that all the materials are compatible with the 3D printing process. We will present a strategy for three-dimensionally integrating diverse classes of materials using a custom-built 3D printer to create fully 3D printed device components built around active electronics. As proof of concept, we have 3D printed quantum dot-based light-emitting diodes (QD-LEDs), polymer-based photodiodes on curvilinear surfaces, flexible displays, and skin-interfaced hybrid devices. These results represent a series of critical steps toward the 3D printing of high performance, active electronic materials and devices.

P.E.S.T.L.E. Orientation - January 27
2023-01-27 16:00 - 17:00 | https://upenn.zoom.us/j/96715197752

PICS Seminar: "Computational fluid dynamics for slurry rheology in flow battery and underlying drag-reduction mechanisms in turbulent flow control"
2023-01-27 14:00 - 15:00 | https://upenn.zoom.us/j/96715197752
Email jnespos@seas.upenn.edu for the Zoom link.
This talk will start by introducing diverse fluid-mechanics research conducted in the Park research group, including complex fluids, electrokinetics, biofluids, transition-to-turbulence, and turbulent flow. I will then focus on two projects at very different flow regimes. For both projects, the modeling, analysis, and computation will be presented along with their engineering applications. The first project is dedicated to a creeping flow or Stokes flow, where dynamics and rheology of highly conductive particle suspensions in an electric field are investigated to help design flow battery slurries. Notably, the negative particle pressure is found to arise at high concentrations, which could be considered a first-of-its-kind in such particle systems. The second project is dedicated to a high-speed flow or turbulent flow, where three flow-control methods are investigated to elucidate their underlying drag-reduction mechanisms. These methods include imposing an external body force, adding long-chain polymers, and utilizing slip surfaces. A temporal analysis based on high- and low-drag periods is employed, showing that the polymer and slip methods exhibit a similar mechanism, while the body force method is different. I will conclude by providing the implications of these different drag-reduction mechanisms.

MSE Seminar: "Bio-inspired Design, Mechanics, and Manufacturing of Architected Cementitious Materials"
2023-01-27 12:00 - 13:00 | LRSM Reading Room, 3231 Walnut St., Philadelphia, PA, 19104, United States
Dr. Moini’s research is focused on bio-inspired design and development of architected materials using novel additive manufacturing processes and automated robotic technologies for applications in civil and energy infrastructure. His work is motivated by the intellectual challenge of understanding the mechanics of intrinsically brittle engineering materials and the development of ductile and flaw-tolerant responses using biomimetic design principles and new material assemblies. Such materials can provide advanced functionality and damage-tolerant behaviors and allow for asking interesting questions about the interplay between desired materials properties such as toughness and strength. Dr. Moini’s other areas of research include integrated multi-component autonomous manufacturing, early-age deformations of colloidal materials in additive processes, packing and solidification of particulate systems, and applying interior tomography techniques to understand the processing-structure-function relationships in architected and additively manufactured brittle ceramic and cement-based materials.

Spring 2023 GRASP on Robotics: Frank Dellaert, Georgia Tech, "Factor Graphs for Perception and Action"
2023-01-27 10:30 - 11:45 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
This is a hybrid event with in-person attendance in Wu and Chen and virtual attendance via Zoom. This week’s presenter will be virtual.
ABSTRACT
Factor graphs have been very successful in providing a lingua franca in which to phrase robotics perception and navigation problems. In this talk I will re-visit some of those successes, also discussed in depth in a recent review article. However, I will focus on our more recent work in the talk, centered on using factor graphs for *action*. I will discuss our efforts in motion planning, trajectory optimization, optimal control, and model-predictive control, highlighting SCATE, our recent work on collision avoidance for autonomous spacecraft.

BE Doctoral Dissertation Defense: "Quantitative Methods for Improving Neurostimulation Therapy in Epilepsy" (Brittany Scheid)
2023-01-26 10:00 - 12:00 | Glandt Forum, Singh Center for Nanotechnology, 3205 Walnut Street, Philadelphia, PA, 19104, United States
The Department of Bioengineering at the University of Pennsylvania and Dr. Brian Litt are pleased to announce the Doctoral Dissertation Defense of Brittany Scheid.

Title: QUANTITATIVE METHODS FOR IMPROVING NEUROSTIMULATION THERAPY IN EPILEPSY

Date: January 26th, 2023
Time: 10am
Location: Glandt Forum, Singh Center

Zoom Link: https://upenn.zoom.us/j/92066299273

The public is welcome to attend.

CBE/BE Seminar: "Targeting Sugars for Immunotherapy in Cancer and Beyond" (Jessica Stark, Stanford)
2023-01-25 15:30 - 16:30 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Co-hosted by the Departments of Chemical and Biomolecular Engineering & Bioengineering.
New paradigms to harness the immune system are urgently needed to address unmet needs in human health. I am working to understand and engineer glycoimmunology – the roles of sugars, or glycans, in the immune system – to bridge this gap. During my PhD, I developed a platform called iVAX for rapid and portable production of conjugate vaccines, a class of FDA-approved vaccines that use glycans to elicit antibacterial immunity. I showed that iVAXderived conjugate vaccines protected mice against lethal pathogen challenge. My iVAX approach has the potential to accelerate development and distribution of vaccines to address emerging drug-resistant bacteria. As a postdoctoral fellow, I designed antibody-lectin (AbLec) chimeras to target glycans that act as immune checkpoints in cancer. I showed that AbLecs potentiated tumor killing by binding and blocking tumor-associated glycans that otherwise inhibit anti-cancer immune responses. AbLecs represent a new modality of cancer immunotherapy that promises to increase the fraction of patients who benefit from treatment. My independent group will work to realize the full potential of glycoimmunology for human health, by developing new immunotherapy modalities and uncovering new drug targets.While we will initially focus on fundamental questions and therapeutic applications in cancer, in the long term we will apply our synergistic platform technologies to additional therapeutic contexts, including autoimmunity, infection, and neurodegeneration.

ASSET Seminar: What makes learning to control easy or hard?, Nikolai Matni (University of Pennsylvania)
2023-01-25 12:00 - 13:30 | Levine 307, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Presentation Abstract:
Designing autonomous systems that are simultaneously high-performing, adaptive, and provably safe remains an open problem. In this talk, we will argue that in order to meet this goal, new theoretical and algorithmic tools are needed that blend the stability, robustness, and safety guarantees of robust control with the flexibility, adaptability, and performance of machine and reinforcement learning. We will highlight our progress towards developing such a theoretical foundation of robust learning for safe control in the context of two case studies: (i) characterizing fundamental limits of learning-enabled control, and (ii) developing novel robust imitation learning algorithms with sample-complexity guarantees. In both cases, we will emphasize the interplay between robust learning, robust control, and robust stability and their consequences on the sample-complexity and generalizability of the resulting learning-based control algorithms.

ESE Spring Seminar - "3D Functional Mesostructures: From Neural Interfaces to Environmental Monitors"
2023-01-24 12:30 - 13:30 | Raisler Lounge (Room 225), Towne Building, 220 South 33rd Street, Philadelphia, PA, 19104, United States
Complex, three dimensional (3D) micro/nanostructures in biology provide sophisticated, essential functions in even the most basic forms of life. Compelling opportunities exist for analogous 3D structures in man-made devices, but existing design options are highly constrained by comparatively primitive capabilities in fabrication and growth. Recent advances in mechanical engineering and materials science provide broad access to diverse, highly engineered classes of 3D architectures, with characteristic dimensions that range from nanometers to centimeters and areas that span square centimeters or more. The approach relies on geometric transformation of preformed two dimensional (2D) precursor micro/nanostructures and/or devices into extended 3D layouts by controlled processes of substrate-induced compressive buckling, where the bonding configurations, thickness distributions and other parameters control the final configurations. This talk reviews the key concepts and focuses on the most recent developments with example applications in areas ranging from mesoscale microfluidic/electronic networks as neural interfaces, to bio-inspired colorimetric microfliers as environmental sensing platforms.

MEAM Seminar: "Toward Physics-informed Machine Intelligence via Graph Discovery"
2023-01-24 10:00 - 23:30 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Advances in machine learning and reduced-order modeling are rendering construction of digital twins for complex systems possible. We are using these tools to perform scientific discovery, design optimization, and data-informed decision making in diverse applications. In this talk we (1) show how graphs may be used to build robust digital twins in high-consequence engineering settings and (2) present ongoing work developing them to perform AI-enhanced scientific discovery. The long-term objective of this work is to use ML not just to identify patterns/surrogates from data, but to emulate human-like cognition linking physics to interpretable causal mechanisms.
First, ML-accelerated multiphysics models require mathematical foundations (stability/accuracy/structure-preservation) to reliably couple component models together into a digital twin. We introduce a finite element exterior calculus to discover structure-preserving Whitney forms. This learning framework reveals physically-relevant control volumes with accompanying integral balance laws which naturally encode physical structure in terms of a graph. The resulting models provide speedups of 10000x for multiscale problems while providing stability and conservation guarantees associated with traditional finite element-based simulation. With a predictive digital twin in hand, we next sketch how they can be used to reveal causal relationships in large multimodal datasets. Multimodal scientific data may be combined and embedded into directed acyclic graphs which encode interpretable causal relationships. Unsupervised discovery of causal graphs provide a means of identifying exploitable scientific relationships or precursors to failure/rare events.

P.E.S.T.L.E. Orientation - January 20
2023-01-20 16:00 - 17:00 | https://upenn.zoom.us/j/96715197752

PICS/MEAM Seminar: "A Low Rank Tensor Approach for Nonlinear Vlasov Simulations"
2023-01-20 14:00 - 15:00 | PICS Conference Room 534 – A Wing , 5th Floor, 3401 Walnut Street, Philadelphia, PA, 19104, United States
In this work, we present a low-rank tensor approach for approximating solutions to the nonlinear Vlasov equation. Our method takes advantage of the tensor-friendly nature of the differential operators in the Vlasov equation to dynamically and adaptively construct a low-rank solution basis through the discretization of the equation and an SVD-type truncation procedure. We utilize finite difference WENO and discontinuous Galerkin spatial discretizations, along with a second-order strong stability preserving multi-step time discretization. To preserve conservation properties, we develop low-rank schemes with local mass, momentum, and energy conservation for the corresponding macroscopic equations. The mass and momentum are conserved using a conservative SVD truncation, while the energy is conserved by replacing the energy component of the kinetic solution with one obtained from a conservative scheme for the macroscopic energy equation. We employ hierarchical Tucker decomposition for high-dimensional problems, and demonstrate the high-order convergence, efficiency, and local conservation properties of our algorithm through a series of linear and nonlinear Vlasov examples.

BE Seminar: "Tissue Architecture Driven by Immune Cells" (John Hickey, Stanford University)
2023-01-19 15:30 - 16:30 | Glandt Forum, Singh Center for Nanotechnology, 3205 Walnut Street, Philadelphia, PA, 19104, United States
“Tissue Architecture Driven by Immune Cells”
John has developed multiplexed spatial omics techniques and computational tools to decode critical interactions within the multidimensional data (e.g., multiscale models and deep learning algorithms). He applied these tools to understand spatial relationships of cells within the healthy human intestine, inflammation induced cancers (esophageal cancer), and in T cell therapy for cancer. His lab will bridge spatial-omics technology, computational algorithm development, and engineering biology, to resolve spatiotemporal mechanisms governing multiple scales of biology, with a first application in cell therapies. His interdisciplinary training enables him to “speak” multiple scientific languages to facilitate critical collaborations across scientific disciplines.

POSTPONED - MSE Seminar: “Additive Manufacturing of Intermetallic: A Designer’s Approach”
2023-01-19 10:30 - 11:30 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Modern materials contain extraordinary levels of complexity, with components spanning a hierarchy of length scales. Designing materials with complex microstructures and demonstrating unique behaviors would be difficult solely using a reductionist approach to materials development. A powerful utility in this endeavor is using multiple, correlative, and scaffolding computational tools. This talk focused on using an integrated materials design approach spanning electronic structure calculations to thermodynamics modeling and paired with combinatorial experimental methods to produce a high-temperature aluminum-based intermetallic for additive manufacturing.

Spring 2023 GRASP SFI: Michael Johnson, Philadelphia Robotics Coalition "Building STEM Equity through Robotics"
2023-01-18 15:00 - 16:00 | Levine 307, 3330 Walnut Street, Philadelphia, PA, 19104, United States
This is a hybrid event with in-person attendance in Levine 307 and virtual attendance via Zoom.
ABSTRACT
Philadelphia Robotics Coalition founder, and School District of Philadelphia engineering teacher Michael Johnson discusses how Philadelphia public schools are using the competitive FIRST robotics programs to build STEM equity in our city. With the goal to inspire and prepare the next generation of STEM leaders in Philadelphia, the Coalition provides training, support, and resources for 180 robotics teams so that students in any neighborhood can access the learning, experiences, and networks surrounding them in the Philadelphia STEM community. Michael will also explain ways that GRASP students and researchers can get involved in this effort in a meaningful way across a continuum of time commitment levels.

ASSET Seminar: Domain Adaptation Under Causally Structured Distribution Shifts, Zachary Lipton (Carnegie Mellon University)
2023-01-18 12:00 - 13:30 | Levine 307, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Presentation Abstract:
Faced with unlabeled data in deployment that is sampled from a different distribution than that which generated the training data, all bets are off. Moreover, while numerous heuristics have been proposed for this vague setting, it remains unclear when any among them are applicable. One way to render these problems identifiable is to impose some (assumed) causal structure, both over how the variables are related to each other, which factors are potentially manipulable (and, complementarily, which are domain-invariant). Unlike conventional problems in causality, where the goal is to estimate the effect of a manipulation (a change in the policy for prescribing the treatment), here the manipulation has already happened, and our goal is to leverage the causal structure to adapt our predictors appropriately. In this talk, I will discuss some structures under which these problems are identifiable and some of the challenges (and solutions) for applying these ideas in deep learning settings.

MEAM Seminar: "Multifunctional Soft Materials for Electronics, Robots, and Adhesives"
2023-01-17 10:00 - 11:30 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
Multifunctional soft materials and interfaces create intriguing new opportunities to enhance performance through programmable and adaptable properties. I will discuss: 1) Novel material architectures of solid-liquid soft composites for electronics, 2) Switchable and programmable materials for adhesion control, and 3) Morphing materials for soft robotics. For soft composites, I will show how liquid metal droplets incorporated into elastomers enables exceptional combinations of soft elasticity and electrical and thermal properties for self-healing and recyclable circuits. For adhesives, I will discuss how we couple switchable, octopus-inspired adhesives with embedded sensing, processing, and control for robust underwater manipulation. This enables a wearable glove where an array of adhesives and sensors creates a biomimetic adhesive skin to manipulate diverse underwater objects. Metamaterial adhesives are also created that exhibit strong and reversible adhesion with spatially selective adhesion strength through programmed cut architectures in adhesive films. These properties are achieved by using cuts to trap adhesive cracks at predetermined locations and then forcing the crack to reverse direction and propagate backwards to separate. By combining active materials with programmed geometry, I will then introduce multifunctional morphing materials with reversible, rapid, and lockable polymorphic reconfigurability. By integrating these materials with onboard control, motors, and power, we can create a soft robotic morphing drone which autonomously transforms from a ground to air vehicle for multiple locomotion modes. These approaches provide model systems to study fundamental material properties while enabling electronic skins, soft robots, and advanced adhesives for a variety of soft matter systems.

P.E.S.T.L.E. - MLK, Jr. Day of Service Information Session
2023-01-16 16:00 - 17:00 | Heilmeier Hall (Room 100), Towne Building, 220 South 33rd Street, Philadelphia, PA, 19104, United States
Join us on Monday, January 16 at 4:00 pm in Towne Heilmeier Hall (Room 100) to discuss the impact community engagement has on the Philadelphia community and its long-lasting effect in our daily lives! Panelists include:
Chanda Jefferson- Director of Community Engagement & Outreach in the Office of Diversity Equity and Inclusion
Emylee Fleshman- Program Coordinator at Penn Foods and Wellness Collaborative
Joel Wilson- Founder & Executive Director of TechCORE2
Ruben Jones, MHS- Executive Director of Frontline Dads
For any questions, email pestle@seas.upenn.edu.

MSE Seminar: “Building With Fluids: A Lazy Approach to Fabrication”
2023-01-12 10:30 - 11:30 | Wu and Chen Auditorium (Room 101), Levine Hall, 3330 Walnut Street, Philadelphia, PA, 19104, United States
In nature, organized arrays of elements arise spontaneously from the interactions between their component parts, e.g. reaction-diffusion problems, clustering colloidal particles and granular media, wrinkling surfaces, propagating cracks and flowing liquids. In the wake of biomimicry, I will discuss several strategies aiming to harness mechanical instabilities in flowing liquids, e.g. coiling, droplet formation, digitation, drainage, capillary suction, and use the regular shapes and universally self-organized patterns they naturally produce as templates for materials design. These flows are “frozen” as the liquids we use solidify into solids, e.g., through curing, cooling or evaporation. The shapes and patterns they form are universal and transcend the traditional divisions between scientific fields or even between living and inert matter. I will show that these similarities result from the mathematical analogies in the rules that govern pattern formation. In turn, I will demonstrate how to compose with these rules to augment our manufacturing capabilities, e.g. in soft robotics.

MEAM Seminar: "Role of Water in the Mechanics of Cells and Tissues"
2023-01-12 10:00 - 11:30 | Glandt Forum, Singh Center for Nanotechnology, 3205 Walnut Street, Philadelphia, PA, 19104, United States
A large fraction of cell and tissue mass is made of water. The flow of water across the cell surface follows osmotic and hydraulic pressure gradients, and is actively controlled by the cell. This physical fact suggests that the mechanical behavior of cells is intimately connected with cell ionic homeostasis and osmotic control. In this talk, we will describe some of our recent experimental and modeling work on water dynamics in cells. We explore how cells control their cytoplasm water content and therefore the cell size. We will describe how cells can use directional flow of water to propel themselves and migrate, and in the case of epithelia, pump fluid between tissue compartments. In the later case, epithelial pumping of water can strongly influence tissue shape and morphogenesis.

ESE PhD Thesis Defense: "Compositional Methods for Agile Quadrupedal Behaviors"
2023-01-06 15:00 - 17:00 | PERCH 303, Pennovation 3rd Floor, 3401 Grays Ferry Avenue, Bldg 6176, Philadelphia, PA, 19146, United States
The last decade has witnessed a proliferation of legged machines with high power and force densities, as well as a commensurate development of locomotion controllers which achieve impressive empirical demonstrations. Yet, despite showing promise as a means of navigating rough terrain, these machines – and the locomotion controllers which animate them – are still restricted to practical applications where interactions with complex and broken terrain can be avoided or where such features are absent altogether, in spite of the fact these interactions are what distinguish legged platforms from their tracked and wheeled counterparts. Indeed, mastering locomotion over difficult terrain has long been the aim of legged robotics research, and requires the development of controllers which enable a specific machine to interact with and overcome obstacles in a given environment. Recently, state-of-the-art design methods for locomotion controllers have sought to meet this challenge by relying on accurate modeling of the platform, detailed descriptions of the environment, and a preconceived plan as to how the obstacles will be overcome. Often, many of these required data are acquired during design time, and therefore may not be readily applicable to experimental settings which can vary greatly from a designer’s anticipated description. To obtain locomotion behaviors which are broadly applicable across platform, task, and environment, the controllers which constitute them must be synthesized at run time; both to directly utilize environmental features, as well as respond to stimuli and disturbances – all of which are unknown a priori. A much more general framework for producing locomotion behavior is therefore required; one that can be applied to a broad range of machines and in a broad range of environments, and must possess metrics which allow for the evaluation of the applicability of the behavior in nearly real-time.
This thesis work begins the development of behavioral synthesis tools that are generalizable, and that enable the generation of agile and flexible behaviors from a predefined set of composable constituent “symbols”. In turn, these symbols can be tuned and adapted to suit a wide variety of platforms, environments, and tasks. By taking well-established notions of template dynamics Full and Koditschek (1999), sequential compositional techniques Burridge et al. (1999), and parallel compositional techniques pioneered by De and Koditschek (2015), a set of template “letters” which can be composed in parallel are identified, and then combined to form parallel composition “syllables”. These syllables are then assembled sequentially to form behavior “words”, which can be flexibly applied in a wide variety of situations. The utility of these synthesized behaviors is augmented further by making use of an “Extended Ground Reaction Complex” (EGRC) Topping et al. (2017) which provides a simplified representation of the salient features in an environment so that they can be explicitly targeted during behavior design and incorporated into the synthesized actions.
In all, this thesis seeks to offer a valuable and flexible set of tools to the robotic behavior designer. The empirical evidence and conceptual insight presented here offers a companion to the state-of-the-art used in legged locomotion today; offering a simple, flexible, and reusable option to aid in locomotion controller design, and beginning to lay the foundation of a symbolic representation of legged behaviors.
