Experience

National Institute of Standards and Technology

Materials Science and Engineering Division • Gaithersburg, MD

Research Engineer • 2017 — Present

Maintained 70-node HPC cluster and data storage; improved research reproducibility by centralizing software builds; alleviated filesystem resource contention through workflow analysis and user education. Orchestrated democratic elections for High Performance Computing Carpentry, leading to incubation as a Carpentries Lesson Program.

Postdoctoral Associate • 2015 — 2017

Implemented phase-field model for solid-state transformation in alloy systems with three components and four phases, analogous to Inconel 625, to simulate microstructure evolution during heat treatment of additively manufactured parts. Produced thermodynamic models through simplification of quantitative CALPHAD databases while retaining key phase diagram features, using computer algebra systems to accurately generate expressions and multivariable derivatives.

DayStar Technologies

Materials Development Group • Clifton Park, NY

Process Engineer (part-time during M.S.) • 2009 — 2011

Process Engineer • 2009 — 2009

Process Technician • 2006 — 2008

Achieved 72× scaleup in CdS deposition area with only 6× increase in waste generation. Researched alternatives to chemical bath deposition of CdS thin films, including nontoxic materials and novel reactor geometries. Traveled to Helsinki, Finland, to evaluate an atomic layer deposition reactor and reported back to senior management.

Education

Rensselaer Polytechnic Institute

Doctor of Philosophy, Materials Engineering • Troy, NY • 2011 — 2015

Thesis: "Bias in Polycrystal Topology Caused by Grain Boundary Motion by Mean Curvature"

Performed large-scale phase field simulations of normal isotropic grain growth on high performance computing clusters including AMOS, an IBM Blue Gene/Q supercomputer. Designed and implemented algorithms to reconstruct polyhedral grain topology (faces, edges, and vertices) from diffuse interfaces in 2D and 3D phase field datasets. Found the process of triangular face elimination responsible for biasing topology in populations of polyhedral grains in synthetic, simulated, and real metal microstructures.

Master of Science, Materials Engineering • Troy, NY • 2009 — 2011

Thesis: "Effects of Magnesium(II) on Zinc Oxide Nanorod Growth From Aqueous Solution"

Designed experiments to deposit ZnO on glass substrates using a novel flow-through aqueous chemical reactor. Found minor effects of Mg2+ ions on ZnO film stress and lattice parameters.

Bachelor of Science, Chemical Engineering • Troy, NY • 2002 — 2006

Publications

A. Reid, A. O'Cais, T. Keller, W. Purwanto, and A. Alim Rasel. "HPC Carpentry: A scalable, peer-reviewed training program to democratize HPC access." Journal of Computational Science Education 15 (2024) 32—34. DOI: 10.22369/issn.2153-4136/15/1/6.

D. Wheeler, T. Keller, S. DeWitt, A. Jokisaari, D. Schwen, J. Guyer, L. Aagesen, O. Heinonen, M. Tonks, P. Voorhees, and J. Warren. "PFHub: The Phase-Field Community Hub. " Journal of Open Research Software 7 (2019) 29. DOI: 10.5334/jors.276.

T. Keller, G. Lindwall, S. Ghosh, L. Ma, B. Lane, F. Zhang, U. Kattner, J. Heigel, E. Lass, Y. Idell, M. Williams, A. Allen, J. Guyer, and L. Levine. "Application of finite element, phase-field, and CALPHAD-based methods to additive manufacturing of Ni alloys. " Acta Materialia 139 (2017) 244—253. DOI: 10.1016/j.actamat.2017.05.003.

T. Keller, B. Cutler, E. Lazar, and D. Lewis. "Comparative grain topology. " Acta Materialia 66 (2014) 414—423. DOI: 10.1016/j.actamat.2013.11.039.

T. Keller, B. Cutler, M. Glicksman, and D. Lewis. "Enumeration of polyhedra for grain growth analysis. " In Proceedings of the First International Conference on 3D Materials Science (Seven Springs, PA: 2012) 97—106. DOI: 10.1007/978-3-319-48762-5_15.

Recognition

U.S. Department of Commerce

Bronze Medal Award • 2021

"The group is recognized for leading a stakeholder community to establish benchmarks for evaluating and validating phase field simulation software useful to the design and manufacture of advanced materials. The group convened and led 10 workshops since 2015 to establish eight distinct benchmark challenges, and to determine stakeholder needs for a benchmark repository and database. The resulting digital infrastructure that the group built, PFHub, is used by scientists worldwide and is broadly recognized as the world’s authoritative resource for validating phase field simulation software and results."

National Institute of Standards and Technology

Material Measurement Laboratory Accolade • 2018

"For exceptional contribution to the field of metal additive manufacturing with a focus on developing integrated simulation methods to predict microstructure evolution based on phase-field models, computational thermodynamics, and finite element analysis."

Acta Materialia and Scripta Materialia

Outstanding Reviewer Award • 2017 and 2018

Presentations*

2020

2019

2018

2017

2016

2014

2013

2012

*Presenter's name is underlined.

Posters*

  • T. Keller and D. Lewis. "Trijunction drag affects grain topology." NIST Chapter of Sigma Xi, Annual Postdoctoral Poster Session. Gaithersburg, MD: February 19, 2016.
  • T. Keller and D. Lewis. "Grain topology from 3D phase-field simulations." Eastern New York Chapter of ASM International, Spring Symposium. Troy, NY: November 18, 2014.
  • T. Keller, B. Cutler, G. Yauney, and D. Lewis. "Grain topologies in synthetic, simulated, and real microstructures." Rensselaer Moves into Petascale Computing: Celebration & Workshop. Troy, NY: October 3, 2013.
  • T. Keller, B. Cutler, G. Yauney, and D. Lewis. "Topological distributions in synthetic microstructures and grains." 8th International Conference on Porous Metals and Metallic Foams (MetFoam). Raleigh, NC: June 23-26, 2013.
  • D. Lewis, G. Saunders, S. Rock, T. Keller, J. Mao, M. Muench, J. Symons, D. Hoffman, M. Oullette, and C. LaBarre. "Development of an automated serial sectioning system." CATS/CEG Advanced Manufacturing Conference. Troy, NY: April 22, 2013.
  • T. Keller, G. Yauney, B. Cutler, and D. Lewis. "Grain populations in topological space." Eastern New York Chapter of ASM International, Spring Symposium. Troy, NY: December 5, 2012.

*Presenter's name is underlined.

Skills

Scientific Computing

  • Teaching as a Carpentries Instructor: Python, Unix Shell, Version Control.
  • Programming languages: C, C++, Python, shell (bash); CUDA, MPI-2/MPI-IO, OpenMP.

Experimental Techniques

  • Metallographic polishing and etching: Fe, Cr, Cu, Ni, Ti, and Zn alloys
  • Scanning electron microscopy (SEM) of metal and semiconductor specimens
  • X-ray diffractometry of semiconducting thin films
  • UV-visible light spectrophotometry of semiconducting thin films
  • Contact profilometry of metal, metalloid, and semiconductor thin films

Project Links