JOPSS - Search Results

Journal Articles

Poincar integral invariant and momentum conservation in symplectic time integration of Hamiltonian partial differential equations

Sasa, Narimasa

Journal of the Physical Society of Japan, 86(7), p.074006_1 - 074006_6, 2017/07

https://doi.org/10.7566/JPSJ.86.074006

Times Cited Count：2 Percentile：21.19(Physics, Multidisciplinary)

The momentum conservation law is investigated in numerical time evolutions of discretized Hamiltonian partial differential equations using symplectic integrators. Our investigation is based on the equivalence between the total momentum and the Poincare integral invariant of the system following our previous work. By introducing a Fourier interpolation method that is a canonical transformation, the total momentum of the system is shown to be an exact conserved quantity if the Hamiltonian possesses a discrete translational invariance and aliasing errors do not appear in the time evolutions. In addition, we perform numerical simulations that demonstrate the validity of our theoretical results under several conditions. Consequently, all symplectic integrators for discretized Hamiltonian partial differential equations are shown to inherit the property of the simultaneous conservation of the total momentum and approximated energy.

Journal Articles

Maximum entropy estimation of electron cyclotron emission spectra from incomplete interferograms in ELMy H-mode tokamak experiment

Isayama, Akihiko; Iwama, Naofumi*; Showa, Takeshi*; Hosoda, Yosuke*; Isei, Nobuaki; Ishida, Shinichi; Sato, Masayasu

Japanese Journal of Applied Physics, Part 1, 42(9A), p.5787 - 5796, 2003/09

https://doi.org/10.1143/JJAP.42.5787

Times Cited Count：3 Percentile：15.63(Physics, Applied)

no abstracts in English

Journal Articles

An Expansion of parallel numerical computing library (PARCEL) to vector-parallel computer, 1; Fast fourier transforms

Hagiwara, Ichiro*; Li, W.*; Nakata, Susumu*; Yamada, Susumu

Keisan Kogaku Koenkai Rombunshu, 61(1), p.205 - 208, 2001/05

no abstracts in English

JAEA Reports

Study of vibrational spectra of interlayer water in Na-Smectite by means of molecular dynamics simulations

Suzuki, Satoru; Kawamura, Katsuyuki*

JNC TN8400 2001-005, 41 Pages, 2001/04

JNC-TN8400-2001-005.pdf:1.1MB

A correlation between molecular structure and a vibrational spectrum of interlayer water in Na-smectite was investigated by means of Molecular Dymamics (MDs) simulations. Detailed comparison of simulation results with IR spectroscopic observations for the water-smectite system indicated good agreement. Internal vibrational spectra of water were obtained by the Fourier transformation of velocty auto-correlation function of hydrogen atom. A stretching vibrational spectrum of interlayer water consisted of a broad band with a peak top around 3400cm $^{-1}$ and a sharp peak around 3650 to 3700cm $^{-1}$ . The fomer broad band was assigned to O-H vibrations between water molecules as bulk water, while the latter band was attributed to O-H ones oriented to siloxane surface through hydrogen bonding. The hydrogen bond distance, determined as the shortest O-O distance by the radial distribution function (RDF), revealed that hydrogen bond distance between water and siloxane surface (O $_{H2O}$ -O $_{clay}$ 3.0 $AA )was larger than that between water molecules (O$_{H2O}$$ -O $_{H2O}$ = ca. 2.8 AA ). These results suggested that interaction between water molecule and siloxane surface weaker than that between water molecules, although they were forced to be oriented.