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Johannes Blaschke

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Johannes Blaschke
Application Performance Specialist
Mobile: (510) 570 7748
1 Cyclotron Road
M/S 59R4010
Berkeley, CA 94720 US

Biographical Sketch

I am an application performance specialist, engaging with scientists to help them optimize their software for large-scale high-performance computing (HPC) environments. I am passionate about helping science teams tackle the problem of deploying their existing algorithms on emergent,  highly heterogeneous hardware.

My interests also include new high-productivity HPC programming models for distributed programs and hardware accelerators; developing cross-facility workflows; and applying novel simulation techniques to broad range of complex systems, as well as inverse problems.

Before coming to NERSC, I worked as a postdoc on developing fluid-structure interaction codes for fluctuating hydrodynamics and active matter simulations. This work was conducted at the Technical University of Berlin, and later the Center for Computational Sciences and Engineering (at LBL).


I lead the NESAP for Data project. NESAP for Data addresses data-intensive science pipelines that process massive datasets from experimental and observational science (EOS) facilities like synchrotron light sources, telescopes, microscopes, particle accelerators, or genome sequencers.

I am a liaison for the ExaFEL project. This project aims to perform near real-time reconstruction of x-ray scattering data using NERSC's systems. X-ray scattering experiments pose a novel use case for cross-facility HPC workflows: near-complete data analysis is needed to effectively use limited beamtime. This brings with it new challenges for HPC: how to move data between experiment and NERSC, and analyze this data in mere minutes. In this project I am helping scientists optimize their codes to make efficient use of emerging Exascale hardware -- and future NERSC systems.

Journal Articles

Weiqun Zhang, Ann Almgren, Vince Beckner, John Bell, Johannes Blaschke, Cy Chan, Marcus Day, Brian Friesen, Kevin Gott, Daniel Graves, Max P. Katz, Andrew Myers, Tan Nguyen, Andrew Nonaka, Michele Rosso, Samuel Williams, Michael Zingale, "AMReX: a framework for block-structured adaptive mesh refinement", Journal of Open Source Software, 2019, 4:1370, doi:

Felix Ruehle, Johannes Blaschke, Jan-Timm Kuhr, Holger Stark, "Gravity-induced dynamics of a squirmer microswimmer in wall proximity", New J. Phys., 2018, 20:025003,

Jan-Timm Kuhr, Johannes Blaschke, Felix Ruehle, Holger Stark, "Collective sedimentation of squirmers under gravity", Soft Matter, 2017, 13:7548--7555,

Johannes Blaschke, Maurice Maurer, Karthik Menon, Andreas Zoettl, Holger Stark, "Phase separation and coexistence of hydrodynamically interacting microswimmers", Soft Matter, 2016, 12:9821-9831, doi: 10.1039/C6SM02042A

Klaus Roeller, Johannes Blaschke, Stephan Herminghaus, Juergen Vollmer, "Arrest of the flow of wet granular matter", Journal of Fluid Mechanics, 2013, 738:407--422, doi: 10.1017/jfm.2013.587

Johannes Blaschke, Juergen Vollmer, "Granular Brownian motors: Role of gas anisotropy and inelasticity", Phys. Rev. E, 2013, 87:040201, doi: 10.1103/PhysRevE.87.040201

Johannes Blaschke, Tobias Lapp, Bjoern Hof, Juergen Vollmer, "Breath Figures: Nucleation, Growth, Coalescence, and the Size Distribution of Droplets", Phys. Rev. Lett., 2012, 109:068701, doi: 10.1103/PhysRevLett.109.068701

Paul Martinsen, Johannes Blaschke, Rainer Kuennemeyer, Robert Jordan, "Accelerating Monte Carlo simulations with an NVIDIA graphics processor", Comput Phys Commun, 2009, 180:1983--1989, doi: 10.1016/j.cpc.2009.05.013