Evaluation of fundamental performance of JAEA's new supercomputer system

Sakamoto, Kensaku; Shimizu, Futoshi; Tsuruoka, Takuya*; Nemoto, Toshiyuki*; Ishikawa, Naota*

JAEA-Testing 2011-005, 88 Pages, 2011/11

JAEA-Testing-2011-005.pdf:5.16MB

A new supercomputer system was deployed at JAEA in March 2010. The system is mainly composed of a large scale Linux cluster system (PRIMERGY BX900: 200Tflops) and a lead off system of RIKEN's K computer (FX1: 12Tflops), whose purposes are to deliver a high-performance parallel computing environment and application code development environment for the K computer, respectively. In this report, we present results of the evaluation of fundamental performance of the system.

Theory of shear banding in metallic glasses and molecular dynamics calculations

Shimizu, Futoshi; Ogata, Shigenobu*; Li, J.*

Materials Transactions, 48(11), p.2923 - 2927, 2007/11

https://doi.org/10.2320/matertrans.MJ200769

Shear bands form in most bulk metallic glasses (BMGs) within a narrowrange of uniaxial strain . We propose this critical condition corresponds to embryonic shear band (ESB)propagation, not its nucleation. To propagate an embryonic shear band, the far-field shear stress must exceed the quasi steady-state glue traction glue of shear-alienated glass until the glass-transition temperature is approached internally due to frictional heating, at which point ESB matures asa runaway shear crack. The magnitude of is governed by recovery, which are extremely fast downhill dissipative processes of timescale comparable to atomic vibrations, which molecular dynamics (MD) simulations can well capture. We model 4 metallic glasses: a binary Lennard-Jones (LJ) system, twobinary embedded atom method (EAM) potential systems, and a quinternary EAM system. Despite vast differences in the structure and interatomic interactions, the glue values from the four MD calculations give predictions in the range of . Large-scale MD simulations of a binary LJ system reveal ESB as shear transformation zones coalesced. Under the condition , ESB is seen to develop into mature shear bands with approaching , while if , ESB does not propagate, becomes diffuse, and eventually dies.

Molecular dynamics study on the formation of stacking fault tetrahedra and unfaulting of Frank loops in FCC metals

Kadoyoshi, Tomoko; Kaburaki, Hideo; Shimizu, Futoshi; Kimizuka, Hajime*; Jitsukawa, Shiro; Li, J.*

Acta Materialia, 55(9), p.3073 - 3080, 2007/05

https://doi.org/10.1016/j.actamat.2007.01.010

Critical conditions have been determined for intrinsic transformation of a vacancy Frank loop into a stacking fault tetrahedron in a face centered cubic metal by the molecular dynamics method. We found that a stacking fault tetrahedron can be formed from the scalene hexagonal vacancy Frank loops of wide range of sizes due to the dissociation of dislocations. We have also found atomistically the dynamical process in which vacancy and interstitial faulted Frank loops transform into perfect loops by the application of the external shear stress or by raising the temperature. We have determined numerically the critical shear stress and temperature for the initiation of unfaulting. The simulation results clearly unveiled the important role of temperature in the unfaulting mechanism of an interstitial Frank loop.

Yield point of metallic glass

Shimizu, Futoshi; Ogata, Shigenobu*; Li, J.*

Acta Materialia, 54(16), p.4293 - 4298, 2006/09

https://doi.org/10.1016/j.actamat.2006.05.024

Shear bands form in most bulk metallic glasses (BMGs) within a narrowrange of uniaxial strain . We proposethis critical condition corresponds to embryonic shear band (ESB)propagation, not its nucleation. To propagate an embryonic shearband, the far-field shear stress must exceed the quasi steady-state glue traction of shear-alienated glass until the glass-transition temperature is approached internally due to frictional heating, atwhich point ESB matures as a runaway shear crack. The incubationlengthscale necessary for this maturation is estimatedto be nm for Zr-based BMGs, below which size sample-scaleshear localization does not happen. In shear-alienated glass, the lastresistance against localized shearing comes from extremely fastdownhill dissipative dynamics (DDD) of timescale comparable to atomicvibrations, allowing molecular dynamics (MD) simulations to capturethis recovery process which governs . We model4 metallic glasses: a binary Lennard-Jones system, two binaryembedded-atom (EAM) potential systems, and a quinternary EAMsystem. Despite vast differences in the structure and interatomicinteractions, the four MD calculations give predictions of and respectively.

Parallel molecular-dynamics simulation on ITBL

Shimizu, Futoshi; Kadoyoshi, Tomoko; Kaburaki, Hideo; Yamagishi, Nobuhiro*; Hasegawa, Yukihiro*; Higuchi, Kenji

Keisan Kogaku Koenkai Rombunshu, 8(2), p.801 - 804, 2003/05

no abstracts in English

Grid computing supporting system on ITBL project

Higuchi, Kenji; Imamura, Toshiyuki*; Suzuki, Yoshio; Shimizu, Futoshi; Machida, Masahiko; Otani, Takayuki; Hasegawa, Yukihiro*; Yamagishi, Nobuhiro*; Kimura, Kazuyuki*; Aoyagi, Tetsuo; et al.

Lecture Notes in Computer Science 2858, p.245 - 257, 2003/00

Prototype of the middleware for Grid project promoted by national institutes in Japan has been developed. Key technologies that are indispensable for construction of virtual organization were already implemented onto the prototype of middleware and examined in practical computer/network system from a view point of availability. In addition several kinds of scientific applications are being executed on the prototype system. It seems that successful result in the implementation of those technologies such as security infrastructure, component programming and collaborative visualization in practical computer/network systems means significant progress in Science Grid in Japan.

PARCEL; Linear equation solvers

Yamada, Susumu; Shimizu, Futoshi; Kaji, Yoshiyuki; Kaburaki, Hideo

Keisan Kogaku Koenkai Rombunshu, 7(1), p.167 - 170, 2002/05

no abstracts in English

High speed calculation for solid molecular dynamics on vector processors

Itakura, Kenichi; Yokokawa, Mitsuo; Shimizu, Futoshi; Kimizuka, Hajime*; Kaburaki, Hideo

Joho Shori Gakkai Kenkyu Hokoku 2001-HPC-88, p.67 - 72, 2001/10

he Earth Simulator which is under development has 640 processor nodes and its peak performance is 40 Tflop/s. In this study, we have evaluated performance of solid molecular dynamics simulation on an SMP node of the Earth Simulator. In molecular dynamics simulation, each particle is influenced by all particles within a cut-off region and the representation of these pairs of particles is made by a matrix. Two matrix representations, compressed row form and jagged diagonal form, are considered for vectorization. The jagged diagonal form is better than the compressed row form in performance on a vector processor for the force calculation of every pairs, because the vector length of the former is longer than that of the latter. However, computational cost for converting the normal matrix form to the jagged diagonal form is quite expensive and the total performance in using the jagged diagonal form is low. Speedup by parallelization with the compressed row form is 2.4 to 2.7 with 8 vector processors.

PARCEL; Performance evaluation by structural analysis calculation

Yamada, Susumu; Shimizu, Futoshi; Imai, Ryuta*; Kimizuka, Hajime*; Kaji, Yoshiyuki; Kaburaki, Hideo

Keisan Kogaku Koenkai Rombunshu, 6(1), p.233 - 236, 2001/05

no abstracts in English

Parrallel molecular dynamics simulation on elastic properties of solid argon

Shimizu, Futoshi; Kimizuka, Hajime*; Kaburaki, Hideo; Li, J.*; Yip, S.*

Proceedings of 4th International Conference on Supercomputing in Nuclear Applications (SNA 2000) (CD-ROM), 10 Pages, 2000/09

no abstracts in English