About

I am a full Professor of Computer Science at Yale, and also an affiliate of American Studies and Ethnicity, Race & Migration (ER& M). I co-direct the Critical Computing Initiative and co-lead the Computer Graphics Group. My research focuses on physics-based simulation, including fire, water, and humans, as well as the history of computer graphics and Asian Americans & STEM.

Research topics

• Computer Science
• Political Science
• Computer graphics (images)
• Engineering
• Data Mining
• Data science
• Artificial Intelligence
• Physics
• Sociology
• Mathematical analysis
• Human–computer interaction
• Theoretical computer science
• Applied mathematics
• Gender studies
• Programming language
• Structural engineering
• Mathematical optimization
• Operating system
• Classical mechanics
• Law
• Optics
• Mechanical engineering
• Mathematics
• Combinatorics

Selected publications

• Hyper-Dimensional Deformation Simulation

  2025-07-23

  articleOpen accessSenior author
  PublisherOA PDFDOI

• Modélisation numérique de l'étendard d'une plume, une membrane fortement anisotrope

  HAL (Le Centre pour la Communication Scientifique Directe) · 2024-05-13

  articleOpen accessSenior author

  National audience

  Publisher

• Curly-Cue: Geometric Methods for Highly Coiled Hair

  2024-12-03 · 5 citations

  articleOpen accessSenior author
  PublisherOA PDFDOI

• The Life and Legacy of Bui Tuong Phong

  2024-07-18 · 1 citations

  articleOpen access1st authorCorresponding

  We examine the life and legacy of pioneering Vietnamese American computer scientist Bùi Tường Phong, whose shading and lighting models turned 50 last year. We trace the trajectory of his life through Vietnam, France, and the United States, and its intersections with global conflicts. Crucially, we present evidence that his name has been cited incorrectly over the last five decades. His family name is Bùi Tường, not Phong. By presenting these facts at SIGGRAPH, we hope to collect more information about his life, and ensure that his name is remembered correctly in the future.

  PublisherOA PDFDOI

• Into the Portal: Directable Fractal Self-Similarity

  2024-07-12 · 3 citations

  articleSenior author

  We present a novel, directable method for introducing fractal self-similarity into arbitrary shapes. Our method allows a user to directly specify the locations of self-similarities in a Julia set, and is general enough to reproduce other well-known fractals such as the Koch snowflake. Ours is the first algorithm to enable this level of general artistic control while also maintaining the character of the original fractal shape. We introduce the notion of placing “portals” in the iteration space of a dynamical system, bridging the aesthetics of iterated maps with the fine-grained control of iterated function systems (IFS). Our method is effective in both 2D and 3D.

  PublisherDOI

• Global Routes and Hidden Labor in the American Mathematical Society’s Cold War Chinese Mathematics Translation Program

  Historical Studies in the Natural Sciences · 2024-06-01 · 1 citations

  articleSenior author

  This article argues that the first important comprehensive efforts by US mathematicians to survey, translate, and disseminate the work of Chinese mathematicians resulted from Cold War geopolitical and scientific competition and economic pressures that emerged in the 1950s and 1960s. The success of the American Mathematical Society’s (AMS) translation program and its journal Chinese Mathematics depended less on official diplomatic channels and more on an informal network of Chinese American mathematicians and librarians in the United States, which provided the infrastructure and hidden labor necessary for transnational mathematical exchange and translation. The history of the Chinese translation project demonstrates the importance of moving beyond the biographies and work of established mathematicians to capture the broader transpacific social history of Chinese American mathematical research and technical labor in the early Cold War. Moreover, the article demonstrates the importance of bringing Asian American history and the history of Cold War science together, as the mathematical and linguistic expertise and labor required came from recently immigrated Chinese American mathematicians caught at the nexus of Cold War anticommunist politics and the incomplete repeal of Chinese exclusion. Historians of mathematics have mostly narrated the late 1940s and early 1950s as a time of anti-communist purges that impacted the lives of Chinese scientists and derailed US–China scientific exchange. Meanwhile, the 1960s have remained unexamined. Instead, we see the ways in which the AMS’s translation program generated important mathematical exchanges that widely impacted mathematics and adjacent fields.

  PublisherDOI

• Generalised tangent stabilised nonlinear elasticity: An automated framework for controlling material and geometric instabilities

  arXiv (Cornell University) · 2024-09-26 · 1 citations

  preprintOpen access

  Tangent stabilised large strain isotropic elasticity was recently proposed by Poya et al. [1] wherein by working directly with principal stretches the entire eigenstructure of constitutive and geometric/initial stiffness terms were found in closed-form, giving fresh insights into exact convexity conditions of highly non-convex functions in discrete settings. Consequently, owing to these tangent eigenvalues an analytic tangent stabilisation was proposed bypassing incumbent numerical approaches routinely used in nonlinear finite element analysis. This formulation appears to be extremely robust for quasi-static simulation of complex deformations even with no load increments and time stepping while still capturing instabilities automatically in ways that are infeasible for path-following techniques in practice. In this work, we generalise the notion of tangent stabilised elasticity to virtually all known invariant formulations of nonlinear elasticity. We show that, closed-form eigen-decomposition of tangents is easily available irrespective of invariant formulation or integrity basis. In particular, we work out closed-form tangent eigensystems for isotropic Total Lagrangian deformation gradient (F )-based and right Cauchy-Green (C)-based as well as Updated Lagrangian left Cauchy-Green (b)-based formulations and present their exact convexity conditions postulated in terms of their corresponding tangent and initial stiffness eigenvalues. In addition, we introduce the notion of geometrically stabilised polyconvex large strain elasticity for models that are materially stable but exhibit geometric instabilities for whom we construct their initial stiffness in a spectrally-decomposed form analytically. We further extend this framework to the case of transverse isotropy where once again, closed-form tangent eigensystems are found for common transversely isotropic invariants.

  PublisherOA PDFDOI

• More Than Killmonger Locs: A Style Guide for Black Hair (in Computer Graphics)

  2024-07-27 · 3 citations

  articleSenior author

  We will cover recent advances and ongoing challenges in the depiction of Black hair, otherwise known as kinky, or Afro-textured hair. In computer graphics, the majority hair research has been in the depiction straight or wavy hair. As a result, many aspects of the aesthetics and mechanics of Black hair remain poorly understood. To help fill this gap, we will present Code My Crown, a free guide to creating Black digital hairstyles that we co-authored in collaboration with a community of game artists and Dove. We also cover styling guidelines for 3D models in the Open Source Afro Hair Library, and present Lifted Curls, our strand simulation technique specifically designed for Afro-textured hair. Finally, we will suggest future directions for hair research.

  PublisherDOI

• Generalised tangent stabilised nonlinear elasticity: An automated framework for controlling material and geometric instabilities

  Computer Methods in Applied Mechanics and Engineering · 2024-12-28 · 5 citations

  articleOpen access

  Tangent stabilised large strain isotropic elasticity was recently proposed by Poya et al. (2023) wherein by working directly with principal stretches the entire eigenstructure of constitutive and geometric/initial stiffness terms were found in closed-form, giving fresh insights into exact convexity conditions of highly non-convex functions in discrete settings. Consequently, owing to these newly found tangent eigenvalues an analytic tangent stabilisation was proposed (for common non-convex strain energies that exhibit material and/or geometric instabilities) bypassing incumbent numerical approaches routinely used in nonlinear finite element analysis. This formulation appears to be extremely robust for quasi-static simulation of complex deformations even with no load increments and time stepping while still capturing instabilities (similar to dynamic analysis) automatically in ways that are infeasible for path-following techniques in practice. In this work, we generalise the notion of tangent stabilised elasticity to virtually all known invariant formulations of nonlinear elasticity. We show that, closed-form eigen-decomposition of tangents is easily available irrespective of invariant formulation or integrity basis. In particular, we work out closed-form tangent eigensystems for isotropic Total Lagrangian deformation gradient ( )-based and right Cauchy–Green ( )-based as well as Updated Lagrangian left Cauchy–Green ( )-based formulations and present their exact convexity conditions postulated in terms of their corresponding tangent and geometric stiffness eigenvalues. In addition, we introduce the notion of geometrically stabilised polyconvex large strain elasticity for models that are materially stable but exhibit geometric instabilities for whom we construct their geometric stiffness in a spectrally-decomposed form analytically. We further extend this framework to the case of transverse isotropy where once again, closed-form tangent eigensystems are found for common transversely isotropic invariants. In this context, we augment the recent work on mixed variational formulations in principal stretches for deformable and rigid bodies, by presenting a mixed variational formulation for models with arbitrarily directed inextensible fibres. Since, tangent stabilisation unleashes an unparallelled capability for extreme deformations new numerical techniques are required to guarantee element-inversion-safe analysis. To this end, we propose a discretisation-aware load-stepping together with a line search scheme for a robust industry-grade implementation of tangent stabilised elasticity over general polyhedral meshes. Extensive comparisons with path-following techniques provide conclusive evidence that utilising tangent stabilised elasticity can offer both faster and automated results.

  PublisherDOI

• Modelling a Feather as a Strongly Anisotropic Elastic Shell

  2024-07-12

  articleOpen access

  Feathers exhibit a highly anisotropic behaviour, governed by their complex hierarchical microstructure composed of individual hairs (barbs) clamped onto a spine (rachis) and attached to each other through tiny hooks (barbules). Previous methods in computer graphics have approximated feathers as strips of cloth, thus failing to capture the particular macroscopic nonlinear behaviour of the feather surface (vane). To investigate the anisotropic properties of a feather vane, we design precise measurement protocols on real feather samples. Our experimental results suggest a linear strain-stress relationship of the feather membrane with orientation-dependent coefficients, as well as an extreme ratio of stiffnesses in the barb and barbule direction, of the order of 104. From these findings we build a simple continuum model for the feather vane, where the vane is represented as a three-parameter anisotropic elastic shell. However, implementing the model numerically reveals severe locking and ill-conditioning issues, due to the extreme stiffness ratio between the barb and the barbule directions. To resolve these issues, we align the mesh along the barb directions and replace the stiffest modes with an inextensibility constraint. We extensively validate our membrane model against real-world laboratory measurements, by using an intermediary microscale model that allows us to limit the number of required lab experiments. Finally, we enrich our membrane model with anisotropic bending, and show its practicality in graphics-like scenarios like a full feather and a larger-scale bird. Code and data for this paper are available at https://gitlab.inria.fr/elan-public-code/feather-shell/.

  PublisherDOI

Recent grants

• CAREER: Enabling Efficient Non-Linearities in Biomechanical Simulations

  NSF · $331k · 2013–2017

Frequent coauthors

• Doug L. James

  Stanford University

  10 shared

• Ming C. Lin

  Chinese Center For Disease Control and Prevention

  9 shared

• Florence Bertails-Descoubes

  Centre Inria de l'Université Grenoble Alpes

  7 shared

• Victor Romero

  Université Grenoble Alpes

  7 shared

• A. M. Darke

  University of California, Santa Cruz

  5 shared

• Jean Jouve

  Institut polytechnique de Grenoble

  5 shared

• Rahul Narain

  Indian Institute of Technology Delhi

  4 shared

• Nils Thuerey

  4 shared

Education

• B.S., Computer Science

  Cornell

  2001

• Ph.D., Computer Science

  UNC Chapel Hill

  2006

• M.S.

  IBM TJ Watson Research Center

  2007

• Other

  Cornell University

  2008

• Other

  Cornell University

  2009

• Other

  University of Saskatchewan

  2011

Awards & honors

• SciTech Oscar (2012, 2022)