About

Twenty years of experience in applying computational science, numerical analysis and scientific computing to solve challenging problems in the areas of medical imaging, organizational behavioral modeling, radio antenna and high-speed electronic circuit design, video and image processing, financial analysis, monitoring of manufacturing processes, and performance testing.

What I Do

I design and implement novel tools to route and analyze data, report results, synthesize models, simulate outcomes and make decisions. Parallel algorithms developed by me solve numerical problems of record-breaking scale. Live exploration is a key aspect of the tools I build, supplementing automated analysis and reporting with the ability to transform and review calculations on the fly. I am keenly interested in broadening the applications of numerical and scientific computing into nontraditional applications and offering unique insight into a wide range of problems.

Public Projects

Although much of my professional effort is devoted to proprietary projects, some of my past work and current diversions are available in public software repositories. Many of these are academic projects and, because they were intended to support my own research, are not thoroughly documented.

• pycwp, a Python package that provides routines for computational wave physics, with an emphasis on acoustic waves.

• habis-tools, a Python package that facilitates medical imaging using measurements of acoustic scattering collected by a novel imaging system developed at the University of Rochester.

• fastsphere, a C program designed to simulate the acoustic scattering response of a collection of spherical objects with differing properties.

• afma, C programs for forward and inverse acoustic scattering by arbitrary, inhomogeneous, three-dimensional media; uses MPI and OpenMP to support massively parallel distributed computing systems. This program relies on the ScaleME fast multipole library, which is a project of the University of Illinois.

• gpg_unlock, a Python utility used by the pam_exec.so PAM module to unlock GPG keys on user login.

• duiadns, a Python program to register dynamic host records for the DUIS DNS service.

• bonjour-repeater, a Python utility that repeats mDNS (Bonjour) records with optional transformations. This program was written to convert CUPS shared printer records into a format recognized by iOS as AirPrint printers.

Academic Publications

• A. J. Hesford, J. C. Tillett, J. P. Astheimer, and R. C. Waag, “Comparison of temporal and spectral scattering methods using acoustically large breast models derived from magnetic resonance images”, J. Acoust. Soc. Am. 136, 682–692 (2014). (DOI: 10.1121/1.4887461)

• A. J. Hesford and R. C. Waag, “Reduced-rank approximations to the far-field transform in the gridded fast multipole method”, J. Comput. Phys. 230, 3656–3667 (2011). (DOI: 10.1016/j.jcp.2011.02.016, PMCID: PMC3086302)

• A. J. Hesford and R. C. Waag, “The fast multipole method and Fourier convolution for the solution of acoustic scattering on regular volumetric grids”, J. Comput. Phys. 229, 8199–8210 (2010). (DOI: 10.1016/j.jcp.2010.07.025, PMCID: PMC2936276)

• A. J. Hesford and W. C. Chew, “Fast inverse scattering solutions using the distorted Born iterative method and the multilevel fast multipole algorithm”, J. Acoust. Soc. Am. 128, 679–690 (2010). (DOI: 10.1121/1.3458856, PMCID: PMC2933255)

• A. J. Hesford, J. P. Astheimer, and R. C. Waag, “Acoustic scattering by arbitrary distributions of disjoint, homogeneous cylinders or spheres”, J. Acoust. Soc. Am. 127, 2883–2893 (2010). (DOI: 10.1121/1.3372641, PMCID: PMC2882659)

• A. J. Hesford, J. P. Astheimer, L. F. Greengard, and R. C. Waag, “A mesh-free approach to acoustic scattering from multiple spheres nested inside a large sphere by using diagonal translation operators”, J. Acoust. Soc. Am. 127, 850–861 (2010). (DOI: 10.1121/1.3277219, PMCID: PMC2830261)

• A. J. Hesford and W. C. Chew, “On preconditioning and the eigensystems of electromagnetic radiation problems”, IEEE Trans. Ant. Propag. 56, 2413–2420 (2008). (DOI: 10.1109/TAP.2008.926783)

• A. J. Hesford and W. C. Chew, “A frequency-domain formulation of the Fréchet derivative to exploit the inherent parallelism of the distorted Born iterative method”, Waves in Random and Complex Media 16, 495–508 (2006). (DOI: 10.1080/17455030600675830)

Diversions

In my free time, I contribute to a some open-source projects. My GitHub profile contains forks of some projects I contribute to or find interesting, in addition to those described above.

If you are looking for an operating system, I highly recommend Void Linux.

When I build Linux systems, I rely on OpenZFS for storage because of its excellent and flexible volume management and replication features. The best way to boot a Linux system from ZFS is zfsbootmenu, a project on which I collaborate to bring FreeBSD-style ZFS boot environments to Linux.

Articles on Linux

I’ve written a few articles that describe my Void Linux setup or its use. They are reproduced here for general interest.

• Using ZFS snapshots and zfsbootmenu to bisect a libvirt “regression”

  • local copy or
  • Reddit copy

• Simple backups with zfs-auto-snapshot, zfs-prune-snapshots and zrep

  • local copy or
  • Reddit copy

• Mutt, IMAP and Mail Synchronization with Runit

  • local copy
  • Reddit copy

• A Home Router Built on Void Linux and ZFSBootMenu

  • local copy
  • Reddit copy

Contact

Find me on LinkedIn for more information about my work.

For a more immediate response, find me as ahesford on the #voidlinux freenode IRC channel.