Articles by Katharine Bailey

STE||AR Spotlight: Patrick Diehl

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Patrick Diehl is a research scientist here in the STE||AR Group at CCT – LSU. He is definitely one of our most active members!  In addition to his extensive research activities and numerous publications, Patrick also teaches in the LSU Math Department and has organized several workshops and events.

Before joining LSU, Patrick was a postdoctoral fellow at the Laboratory for Multiscale Mechanics at Polytechnique Montreal. He received his diploma in computer science at the University of Stuttgart and his Ph.D. in Applied Mathematics from the university of Bonn.

Patrick created and hosted the virtual CAIRO colloquium series in the Spring.  Speakers from across the country, and even internationally, joined to discuss various AI (artificial intelligence) topics.  The series was an overall success and will continue in the Fall.

Patrick is the liaison for universities in Louisiana for the Texas and Louisiana section of the Society for Applied and Industrial Mathematics (SIAM). He is a topic editor for the Journal for Open Source Software (JOSS) for computational fracture mechanics, applied mathematics, C++, asynchronous and task-based programming.

Patrick also cohosts a podcast – FLOSS For Science – with episodes that showcase free, libre and open source software uses in science with the aim to advocate for the usage of Open Source software in academia and higher education.

Patrick’s main research interests are:

Computational engineering with the focus on peridynamic material models for the application in solids, like glassy or composite materials

High performance computing, especially the asynchronous many task system (ATM), e.g. the C++ standard library for parallelism and concurrency (HPX) for large heterogeneous computations.

In addition, Patrick has a deep interest in the usage of Open Source software to enhance the openness of Science. With respect to teaching, he is interested to develop tools to easily introduce C++ and parallel computing to non-computer science students.

Patrick lives in Baton Rouge with his wife Sylvia and their young daughter Ava.  Aside from all the great work he does at LSU, he’s an active family man and enjoys trips to the park and gymnastics lessons for Ava.  Some of their favorite activities are enjoying the local Cajun food and visiting the amazing BREC parks.

GSoC 2021 Participants Announced!

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It is time to announce the participants for in the STE||AR Group’s 2021 Google Summer of Code! We are very proud to announce the names of the 2 students this year who will be funded by Google to work on projects for our group.

These recipients represent the very best of the many excellent proposals that we had to choose from. For those unfamiliar with the program, the Google Summer of Code brings together ambitious students from around the world with open source developers by giving each mentoring organization funds to hire a set number of participants. Students then write proposals, which they submit to a mentoring organization, in hopes of having their work funded.

Below are the students who will be working with the STE||AR Group this summer listed with their mentors and their proposal abstracts.

Participant:

Akhil J Nair, Army Institute Of Technology ( Savitribai Phule Pune University)

Mentors:

Giannis Gonidelis

Hartmut Kaiser

Project: Adapting algorithms to C++ 20 and Ranges TS

I’m Akhil J Nair, a third year undergrad studying computer engineering at AIT, Pune. I’ll be working with the STE||AR group this summer, focusing on the algorithms part of HPX, working on tasks such as adapting the parallel algorithms to C++ 20, adding range overloads, sentinel overloads etc. The algorithms would be adapted to use the tag_invoke customization point mechanism and the C++ 20 overloads will be added according to the C++ 20 Standard. The ranges overloads will also be added as proposed in the C++ extensions to ranges. Adding sentinel overloads and separating the segmented algorithms for the few remaining algorithms will also be done. I’m hoping this would serve as an entry point for me to HPX and the wider world of HPC in general and I look forward to contributing and learning a lot over the coming months.

Participant:

Srinivas Yadav, Keshav Memorial Institute of Technology, Hyderabad, India

Mentors:

Nikunj Gupta

Patrick Diehl

Project:  Add vectorization to par_unseq implementations of Parallel Algorithms

I am Srinivas Yadav currently pursuing my Bachelors in Computer Science at KMIT, Hyderabad, India. I will be working with STE | | AR group for HPX this summer in the area of vectorization for parallel algorithms. Current hpx parallel algorithms do not support vectorization. Vectorization allows the algorithms to use the cpu vector registers and hence performance may be improved by utilising most of the cpu resources and allows us to exploit another level of parallelism. This project aims to implement the support for parallel algorithms with explicit vectorization with new `simd` execution policy by using the c++ experimental simd extensions. I hope contributing to HPX would serve me as a stepping stone to the world of HPC and I am looking forward to learning and contributing more over the coming months.

Octo-Tiger Breakthrough Article

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Our Octo-Tiger team here in the STE||AR Group are making waves with their newly published journal article in Monthly Notices of the Royal Astronomical Society, “Octo-Tiger: A New, 3D Hydrodynamic Code for Stellar Mergers That Uses HPX Parallelisation,”

The paper investigates the code performance and precision through benchmark testing. The authors, Dominic C. Marcello, postdoctoral researcher; Sagiv Shiber, postdoctoral researcher; Juhan Frank, professor; Geoffrey C. Clayton, professor; Patrick Diehl, research scientist; and Hartmut Kaiser, research scientist, all at LSU — together with collaborators Orsola De Marco, professor at Macquarie University and Patrick M. Motl, professor at Indiana University Kokomo — compared their results to analytic solutions, when known and other grid-based codes, such as the popular FLASH. In addition, they computed the interaction between two white dwarfs from the early mass transfer through to the merger and compared the results with past simulations of similar systems.

The LSU Physics and Astronomy press release was picked up by almost a dozen computer science and other media sites, including Phys.org, and SciTechDaily.  This is an exciting breakthrough as the astrophysics code outlined in the article is able to quickly and accurately simulate the collision of stars.

Understanding stars is fundamental to understanding the smaller planets that orbit them and the large galaxies they inhabit. Stars change over million to billion-year timescales in complex ways, particularly if we consider that many of them are orbited by one or more close companions, with which they exchange mass at different stages during their lives. Recent observations of these mass exchanges as flashes of light, or “transients”, show us a fundamentally new paradigm of stellar evolution, where even well-known phenomena like supernovae need to be understood in a new light. We need to include interacting, multiple stars in our models to explain exploding, outbursting, colliding, and merging stars, to interpret the rapidly increasing number of observations of transients and to ultimately create a new model of stellar evolution.

Octo-Tiger is currently optimized to simulate the merger of well-resolved stars that can be approximated by barotropic structures, such as white dwarfs or main sequence stars. The gravity solver conserves angular momentum to machine precision, thanks to a correction algorithm. This code uses HPX parallelization, allowing the overlap of work and communication and leading to excellent scaling properties, allowing for the computation of large problems in reasonable wall-clock times.

The research outlines the current and planned areas of development aimed at tackling a number of physical phenomena connected to observations of transients.

The video by Sagiv Shriber, found here: https://lsu.app.box.com/s/9g41cbz14l2agk3etx0pxy8ityddknty, shows a simulation of the motion of two white dwarfs in each other’s orbits. We are looking down at these two stars as they begin to merge together.

The collaborative Octo-Tiger project continues, and we look forward to their novel and exciting work in now and in the future.

  • Octo-Tiger is funded by: National Science Foundation Award1814967
  • The following computational sources were utilzed to conduct the research: QueenBee2 at Louisiana Optical NetworkInitiative (LONI); BigRed3 at Indiana University was supported by Lilly Endowment, Inc., through its support for the Indiana University Pervasive Technology Institute; and Gadi from  the  National  Computational  Infrastructure (NCI  Australia), an NCRIS enabled capability supported by the Australian Government.

GSoC 2020: Final Reports

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Please find attached the final reports of our successful GSoC students::

Giannis Gonidelis, Adapt parallel algorithms to C++20: Final Report, Blog

Sayef Sakin, Time Series Updates for Traveler: Final Report/Blog

Weile Wei, Concurrent Data structure Support: Final Report/Blog

Mahesh Kale, Pip Package for Phylanx: Final Report/Blog

Pranav Gadikar, Domain decomposition, load balancing, and massively parallel solvers for the class of nonlocal models: Final Report/Blog