Computational Physics on Graphics Processing Units

The use of graphics processing units for scientific computations is an emerging strategy that can significantly speed up various different algorithms. In this review, we discuss advances made in the field of computational physics, focusing on classical molecular dynamics, and on quantum simulations for electronic structure calculations using the density functional theory, wave function techniques, and quantum field theory.Comment: Proceedings of the 11th International Conference, PARA 2012, Helsinki, Finland, June 10-13, 201

Excited-State Electronic Structure with Configuration Interaction Singles and Tamm–Dancoff Time-Dependent Density Functional Theory on Graphical Processing Units

Excited-state calculations are implemented in a development version of the GPU-based TeraChem software package using the configuration interaction singles (CIS) and adiabatic linear response Tamm–Dancoff time-dependent density functional theory (TDA-TDDFT) methods. The speedup of the CIS and TDDFT methods using GPU-based electron repulsion integrals and density functional quadrature integration allows full ab initio excited-state calculations on molecules of unprecedented size. CIS/6-31G and TD-BLYP/6-31G benchmark timings are presented for a range of systems, including four generations of oligothiophene dendrimers, photoactive yellow protein (PYP), and the PYP chromophore solvated with 900 quantum mechanical water molecules. The effects of double and single precision integration are discussed, and mixed precision GPU integration is shown to give extremely good numerical accuracy for both CIS and TDDFT excitation energies (excitation energies within 0.0005 eV of extended double precision CPU results)

Global evolution of a substorm-associated DP2 current system observed by superDARN and magnetometers

This paper deals with an evolution of the electric field in the dayside auroral and equatorial ionosphere during asubstorm on July 16, 1995. A southward turning of the IMF detected by WIND (171 Re) caused enhancements in the auroral electrojet intensity in the 7–10 MLT and 15.5–18.5 MLT sectors as observed by the IMAGE (74-56 cgmlat) and CANOPUS (70-58 cgmlat) magnetometer chains. SuperDARN detected an equatorward motion of the radar scattering region at speeds of several −10 degs/hour in the dayside (05–17 MLT), suggesting an increase in the flux of the open magnetic field in the polar cap. Furthermore, coherent magnetic variations are observed at subauroral to equatorial latitudes simultaneously with the auroral magnetic variations within a temporal resolution of 10 s. This suggests that the electric field increase during the growth phase is established instantaneously around the convection reversal in the 15.5–18.5 MLT sector, and furthermore penetrates instantaneously to mid and low latitudes. SuperDARN detected a continuous equatorward motion of the auroral oval during the expansion phase around the cusp, which implies a continuous magnetic merging at the day-side magnetopause during the expansion phase. A rapid decrease in the electric field is inferred from coherent auroral and equatorial magnetic field decreases during the recovery phase, which may have been caused by northward turning of the IMF. This magnetic field decrease resembles the change in magnetic field of the counter-electrojet at the dip equator in the afternoon sector

CHAMP PhaseB - Executive Summary

The small satellite mission CHAMP was initiated and is primarily funded by the German Space Agency (DARA) as a lead project for the East German space industry. It is defined in its main mission goals by researchers of the GeoForschungsZentrum Potsdam (GFZ), and is conducted under lead of GFZ in cooperation with the German Aerospace Establishment (DLR) and the industry. After completion of an initial feasibility study (Phase A) and of the project's definition/specification phase (Phase B), followed by a two months redesign phase (Phase #DELTA#B), CHAMP is supposed to enter into Phase C/D in late 1996. CHAMP as a geoscientific mission with a multi-purpose and complementary payload shall substantially contribute to one of the basic research objectives of studies of planet Earth, that is, to the determination of the composition, structure, and dynamics of the solid planet, its oceans and atmosphere, and its surrounding envelope of charged particles and fields. CHAMP being one element in a timely sequence of Earth observations and platforms, satellites, and mini-satellites could be a contributor to the acquisition of global, synoptic and long-term measurements of global processes through space and ground instrumentation. CHAMP shall fulfil the criteria of a small satellite mission, i.e., only a few years of development time through the usage of existing sensors and commercial spacecraft subsystem components, and reduced costs through protoflight approach, reduced quality standards and test efforts. The most challenging parts of the CHAMP mission are the variety of payload components especially the accelerometer and the magnetometers, each one with demanding environmental requirements. It is designed to observe both the gravitational as well as the magnetic potential from one platform in order to get a complementary scientific payback. The GPS-receiver on-board CHAMP being employed for gravity field recovery, simultaneously will perform atmosphere and ionosphere profiling by Earth limb sounding. It is also for the first time a three-axes accelerometer will be flown to measure with a required accuracy of 10"-"8 m/s"2 the non-gravitational forces, e.g. air drag, perturbing the satellite's motion. (orig.)SIGLEAvailable from TIB Hannover: RR 6134(96/13) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Dynamic regulation and differential compartmentaliztion of C-type lectin receptors in the dendritic cell membrane

Dendritic cells (DCs) are important antigen-presenting cells in the immune system. They are responsible for the recognition and internalization of pathogens, followed by the induction of antigen specific CD4+ and CD8+ T cell responses, but also for the maintenance of peripheral T cell tolerance

Exascale deep learning for climate analytics

We extract pixel-level masks of extreme weather patterns using variants of Tiramisu and DeepLabv3+ neural networks. We describe improvements to the software frameworks, input pipeline, and the network training algorithms necessary to efficiently scale deep learning on the Piz Daint and Summit systems. The Tiramisu network scales to 5300 P100 GPUs with a sustained throughput of 21.0 PF/s and parallel efficiency of 79.0%. DeepLabv3+ scales up to 27360 V100 GPUs with a sustained throughput of 325.8 PF/s and a parallel efficiency of 90.7% in single precision. By taking advantage of the FP16 Tensor Cores, a half-precision version of the DeepLabv3+ network achieves a peak and sustained throughput of 1.13 EF/s and 999.0 PF/s respectively