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Journal Articles

Estimation of planes of a rock mass in a gallery wall from point cloud data based on MD PSO

Matsuura, Yuto*; Hayano, Akira; Itakura, Kenichi*; Suzuki, Yukinori*

Applied Soft Computing, 84, p.105737_1 - 105737_9, 2019/11

 Times Cited Count:1 Percentile:16.64(Computer Science, Artificial Intelligence)

LiDAR (laser imaging detection and ranging) has been developed to obtain a high-resolution point cloud data indicating the detailed 3D shapes of an object. To identify discontinuities in a rock mass of a tunnel gallery wall, it is necessary to approximate the rock mass surface with small planes. Normal vectors of the planes are important to identify discontinuities. We developed an algorithm for estimation of planes based on multi-dimensional particle swarm optimization (MD PSO) from point cloud data. Point cloud data were segmented into bounding boxes and grouped into clusters by MD PSO. Planes were estimated using the least squares method for point cloud data in the respective clusters. The newly developed MD PSO algorithm was evaluated using point cloud data obtained from a gallery wall. Evaluation was carried out in comparison with the previous developed variable-box segmentation (VBS) algorithm. The MD PSO-based algorithm showed a 7% higher accuracy than that of the VBS algorithm.

Journal Articles

Diffusion behavior of methanol molecules confined in cross-linked phenolic resins studied using neutron scattering and molecular dynamics simulations

Shudo, Yasuyuki*; Izumi, Atsushi*; Hagita, Katsumi*; Yamada, Takeshi*; Shibata, Kaoru; Shibayama, Mitsuhiro*

Macromolecules, 51(16), p.6334 - 6343, 2018/08

 Times Cited Count:9 Percentile:49.31(Polymer Science)

Journal Articles

Feasibility study of nuclear transmutation by negative muon capture reaction using the PHITS code

Abe, Shinichiro; Sato, Tatsuhiko

EPJ Web of Conferences, 122, p.04002_1 - 04002_6, 2016/06

 Times Cited Count:0 Percentile:0.06

Nuclear transmutation has been investigated to reduce long-lived fission products (LLFPs) in high level radioactive wastes. However, the nuclear transmutation is difficult for some LLFPs (e.g., $$^{90}$$Sr, $$^{126}$$Sn and $$^{137}$$Cs) having small cross-sections of fission and neutron capture. Negative muon is examined to be applied for the nuclear transmutation. Low energy negative muon is captured on an atom, and then it can decay or be further captured on its nucleus. When negative muon is captured on nucleus, some light particles and residual nucleus are produced. Negative muon capture process has been implemented into latest version of PHITS. In this study, we studied the feasibility of nuclear transmutation by negative muon capture reaction for LLFPs using PHITS. Negative muon capture reaction on 90Sr is simulated. It is found that 94% of negative muons are captured on nucleus, and 66% of $$^{90}$$Sr become stable nuclides or radioactive nuclides having less than 20 days. It is also found that 15% of $$^{90}$$Sr become $$^{87}$$Rb having longer half-life than that of $$^{90}$$Sr.

Journal Articles

Hydrodynamics driven by ultrashort laser pulse; Simulations and the optical pump - X-ray probe experiment

Inogamov, N. A.*; Zhakhovsky, V. V.*; Hasegawa, Noboru; Nishikino, Masaharu; Yamagiwa, Mitsuru; Ishino, Masahiko; Agranat, M. B.*; Ashitkov, S. I.*; Faenov, A. Y.*; Khokhlov, V. A.*; et al.

Applied Physics B, 119(3), p.413 - 419, 2015/06

 Times Cited Count:6 Percentile:40.44(Optics)

Journal Articles

Atomic and molecular data activities for fusion research at JAERI

Kubo, Hirotaka; Sataka, Masao; Shirai, Toshizo

Journal of Plasma and Fusion Research SERIES, Vol.7, p.352 - 355, 2006/00

no abstracts in English

Journal Articles

Study of light output and response function of liquid organic scintillator for high-energy neutron spectrometry

Satoh, Daiki; Sato, Tatsuhiko; Endo, Akira; Matsufuji, Naruhiro*; Sato, Shinji*; Takada, Masashi*; Ishibashi, Kenji*

Nuclear Science Symposium Conference Record, 2005 IEEE, Vol.3, p.1288 - 1290, 2005/10

The response functions of a BC501A liquid organic scintillator have been measured for incidence of various charged particles to investigate the relationship between the kinetic energy of the charged particles and the light output of BC501A. The experiment was performed at Heavy-Ion Medical Accelerator in Chiba (HIMAC) utilizing spallation reactions by heavy ion bombardment on a graphite target. Charged particles incidental on BC501A were identified with the two-dimensional scatter plot of the time-of-flight and the light output. The light output of the BC501A scintillator was deduced as a function of the kinetic energy of the charged particles, and was compared with the semi-empirical formula. While the experimental data showed a good agreement with the formula for proton and deuteron, the data gave slightly larger values compared with the systematic trend for alpha particle.

Journal Articles

Development of dose monitoring system applicable to various radiations with wide energy ranges

Sato, Tatsuhiko; Satoh, Daiki; Endo, Akira; Yamaguchi, Yasuhiro

Journal of Nuclear Science and Technology, 42(9), p.768 - 778, 2005/09

 Times Cited Count:16 Percentile:74.09(Nuclear Science & Technology)

A new inventive radiation monitor, designated to DARWIN (Dose Assessment system applicable to various Radiations with WIde energy raNges), has been developed for monitoring doses at workspaces of high energy accelerator facilities and on ground. Characteristics of DARWIN were studied by both calculation and experiment. The calculated results indicate that DARWIN gives reasonable estimations of doses at most radiation fields. It was found from the experiment that DARWIN has an excellent property of measuring doses from all particles that significantly contribute to the background dose - photon, muon and neutron with wide energy ranges.

Journal Articles

Influence of multidimensionality on convergence of sampling in protein simulation

Metsugi. Shoichi

Journal of the Physical Society of Japan, 74(6), p.1865 - 1870, 2005/06

 Times Cited Count:0 Percentile:0.01(Physics, Multidisciplinary)

We study the problem of convergence of sampling in protein simulation originating in the multidimensionality of protein's conformational space. Since several important physical quantities are given by second moments of dynamical variables, we attempt to obtain the time of simulation necessary for their sufficient convergence. We perform a molecular dynamics simulation of a protein and the subsequent principal component (PC) analysis as a function of simulation time T. As T increases, PC vectors with smaller amplitude of variations are identified and their amplitudes are equilibrated before identifying and equilibrating vectors with larger amplitude of variations. This sequential identification and equilibration mechanism makes protein simulation a useful method although it has an intrinsic multidimensional nature.

Journal Articles

Study on response function of organic liquid scintillator for high-energy neutrons

Satoh, Daiki; Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Takada, Masashi*; Ishibashi, Kenji*

AIP Conference Proceedings 769, p.1680 - 1683, 2005/05

Response function of liquid organic scintillators is essential to derive the accurate neutron spectrum. Experimental data above 100 MeV, however, are very scarce. The existing Monte Carlo codes, SCINFUL and CECIL, are often used for estimation of the response function instead of the experimental data. These codes are known to reproduce well the response function for incidences below 100 MeV. Unfortunately, the codes are not applicable to the calculation in the higher energy region. In order to determine the response functions above 100 MeV, a new Monte Carlo code, designated as SCINFUL-QMD, has been developed. In the comparison with the experimental data up to 800 MeV, the validation of SCINFUL-QMD was confirmed. The results of SCINFUL-QMD agreed with the experimental data better than those of other calculation codes.

Journal Articles

Development of dose assessment method for high-energy neutrons using intelligent neutron monitor

Satoh, Daiki; Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Takada, Masashi*

NIRS-M-180, p.263 - 264, 2005/05

Response functions of NE213 liquid organic scintillator have been measured to develop a dose assessment method for high-energy neutrons. Spallation reactions by 800 MeV/u Si ions and 400 MeV/u C ions incident into thick carbon targets were utilized for the production of high-energy neutrons. Kinetic energies of neutrons were determined by the time-of-flight (TOF) method. $$gamma$$-ray and charged particle events were eliminated from experimental data in off-line analysis. The measured response functions were used for validation of the simulation by the SCINFUL-QMD code, which is utilized for calculation of the G-function that converts the scintillator response to neutron dose. It was found from the results that SCINFUL-QMD has a good ability to reproduce the response functions.

Journal Articles

Simulation of transitions between "Pasta" phases in dense matter

Watanabe, Gentaro*; Maruyama, Toshiki; Sato, Katsuhiko*; Yasuoka, Kenji*; Ebisuzaki, Toshikazu*

Physical Review Letters, 94(3), p.031101_1 - 031101_4, 2005/01

 Times Cited Count:86 Percentile:91.85(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

XAFS and spectroscopic characterization for the structure and electronic structure of Ce-DMDPhPDA complexes in methanol

Yaita, Tsuyoshi; Shiwaku, Hideaki; Suzuki, Shinichi; Okamoto, Yoshihiro; Shimada, Asako*; Assefa, Z.*; Haire, R. G.*

Physica Scripta, T115, p.302 - 305, 2005/00

The structural parameter and the electronic structure of the complex between cerium and N,N'-dimethyl-N,N'-diphenylpyridine-2,6-carboxyamide(DMDPhPDA) was investigated by XAFS, photo luminescence and excitation spectra. The DMDPhPDA is one of the promising ligands for separation of trivalent actinides from lanthanides. The Ce-K XAFS spectra were measured at BL11XU of SPring-8. The bond distances between the carbonyl oxygens and cerium, and between the pyridyl nitrogen and cerium are 253pm and 264pm, respectively. The bond angle of the plane consisting of the two carbonyl oxygens and nitrogen with cerium was about 180 degree. This complex was a yellow color unique for the DMDPhPDA-lanthanide complexes. The photo absorption peak for the complex was extremely broad, and the peak position was at a higher wavenumber as compared with those for the other lanthanide complexes. The peak in the highest wavenumber of this band may be attributed to the transition between f and d orbitals, which are greatly influenced by the ligand field of the DMDPhPDA. The XANES spectrum of the cerium complex clearly showed that cerium was trivalent.

Journal Articles

Possibility analysis of Cu(InGa)Se$$_{2}$$ thin-film solar cells for space use

Kawakita, Shiro*; Shimazaki, Kazunori*; Imaizumi, Mitsuru*; Kuwajima, Saburo*; Yoda, Shinichi*; Oshima, Takeshi; Ito, Hisayoshi

Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.151 - 154, 2004/10

no abstracts in English

Journal Articles

Molecular dynamics of 8-oxoguanine lesioned B-DNA molecule; Structure and energy analysis

Pinak, M.; O'Neill, P.*; Fujimoto, Hirofumi; Nemoto, Toshiyuki*

AIP Conference Proceedings 708, p.310 - 313, 2004/05

The multiple nanosecond molecular dynamics simulations of DNA mutagenic oxidative lesion - 7,8-dihydro-8-oxoguanine (8-oxoG), complexed with the repair enzyme - human oxoguanine glycosylase 1 (hOGG1) in a physiological aqueous environment, were performed in order to describe the structural and energy changes in DNA and the dynamical process of DNA-enzyme complex formation. In complex the N-terminus of arginine 324 was found located close to the phosphodiester bond of the nucleotide with 8-oxoG enabling chemical reaction(s) between the amino acid and the lesion. The recognition of lesion on DNA, its recognition by repair enzyme and the formation of stable DNA-enzyme complex are necessary conditions for the onset of the successful enzymatic repair process.

Journal Articles

Theoretical study on the alloying behavior of $$gamma$$-uranium metal; $$gamma$$-uranium alloy with 3d transition metals

Kurihara, Masayoshi*; Hirata, Masaru; Sekine, Rika*; Onoe, Jun*; Nakamatsu, Hirohide*

Journal of Nuclear Materials, 326(2-3), p.75 - 79, 2004/03

 Times Cited Count:11 Percentile:61.05(Materials Science, Multidisciplinary)

We have investigated the alloying behavior of g-uranium with 3d transition metals (TMs) using the relativistic discrete-variational Dirac-Fock-Slater (DV-DFS) method. The d-orbital energy (Md) as an alloying parameter well reproduces the alloying behavior of g- uranium metal with TMs: (1) in the case of a large Md value (Ti,V,Cr), the solubility of these TM elements in g-uranium becomes large; (2) in the case of a middle Md value (Mn,Fe,Co), the tendency to form a uranium intermetallic compound with these elements becomes stronger; (3) in the case of a small Md value (Cu), the alloying element is insoluble in g-uranium. The alloying behavior of g-uranium with TMs is also discussed in terms of other parameters such as electronegativity and metallic radius.

Journal Articles

Super radiation tolerance of CIGS solar cells demonstrated in space by MDS-1 satellite

Kawakita, Shiro*; Imaizumi, Mitsuru*; Sumita, Taishi*; Kushiya, Katsumi*; Oshima, Takeshi; Yamaguchi, Masafumi*; Matsuda, Sumio*; Yoda, Shinichi*; Kamiya, Tomihiro

Proceedings of 3rd World Conference on Photovoltaic Energy Conversion (WCPEC-3) (CD-ROM), 4 Pages, 2004/01

The electrical performance of Cu(Ga,In)Se$$_{2}$$ solar cells on MDS-1 which was launched in February 2002 was measured. The CIGS solar cells show superior radiation resistance in space. The short circuit current dose not degrade and the open circuit voltage shows only 1 % degradation after 200 days. On the other hand, in the case of ground test, the recovery of electrical performance of CIGS solar cells are observed at RT. And, the recovery is enhanced by current-injection.

Journal Articles

Effects of pellet expansion and cladding hydrides on PCMI failure of high burnup LWR fuel during reactivity transients

Fuketa, Toyoshi; Sugiyama, Tomoyuki; Nakamura, Takehiko; Sasajima, Hideo; Nagase, Fumihisa

NUREG/CP-0185, p.161 - 172, 2004/00

To provide a data base for the regulatory guide of light water reactors, behavior of reactor fuels during off-normal and postulated accident conditions such as reactivity-initiated accident (RIA) is being studied in the Nuclear Safety Research Reactor (NSRR) program of the Japan Atomic Energy Research Institute (JAERI). A series of experiments with high burnup fuel rods is being performed by using pulse irradiation capability of the NSRR. This paper presents recent results obtained from the NSRR power burst experiments with irradiated PWR fuels with ZIRLO and MDA claddings, and discusses effects of pellet expansion as PCMI (Pellet-Cladding Mechanical Interaction) loading and cladding embrittlement primarily due to hydrogen absorption. Separate-effect studies including tube-burst and ring-tensile tests on Zircaloy cladding also described.

Journal Articles

Electrostatic energy analysis of 8-oxoguanine DNA lesion; Molecular dynamics study

Pinak, M.

Computational Biology and Chemistry, 27(3), p.431 - 441, 2003/07

 Times Cited Count:9 Percentile:46.61(Biology)

One nanosecond molecular dynamics (MD) simulation was performed for two DNA segments each composed of 30 base pairs. The analysis of results was focused on the electrostatic energy that is supposed to be significant factor causing the disruption of DNA base stacking in DNA duplex and may also to serve as a signal toward the repair enzyme informing on the presence of the lesion. This electrostatic potential may signal presence of the lesion to the repair enzyme.

Journal Articles

Computational study of recognition of DNA damages and their repair; 8-oxoguanine oxidative DNA damage with repair enzyme hOGG1

Pinak, M.; Laaksonen, A.

Molecular Mechanisms for Radiation-Induced Cellular Response and Cancer Development, p.266 - 273, 2003/00

The molecular dynamics (MD) simulations of DNA mutagenic oxidative lesion - 7,8-dihydro-8-oxoguanine (8-oxoG), single and complexed with the repair enzyme - human oxoguanine glycosylase 1 (hOGG1), were performed for 1 nanosecond (ns) in order to determine structural changes at the DNA molecule and to describe a dynamical process of DNA-enzyme complex formation. The broken hydrogen bonds resulting in locally collapsed B-DNA structure were observed at the lesion site. In addition the adenine on the complementary strand (separated from 8-oxoG by 1 base pair) was flipped-out of the DNA double helix. In the case of simulation of DNA and repair enzyme hOGG1, the DNA-enzyme complex was formed after 500 picoseconds of MD that lasted stable until the simulation was terminated at 1 ns.

Journal Articles

Calculation of fission reaction in the framework of QMD + SDM

Iwamoto, Osamu; Rong, J.; Fukahori, Tokio; Chiba, Satoshi

Journal of Nuclear Science and Technology, 39(Suppl.2), p.128 - 131, 2002/08

The nucleon induced fission cross section and the fragment distribution are calculated using the Quantum Molecular Dynamics (QMD) plus Statistical Decay Model (SDM) in the nucleon energy range 10 MeV to 10 GeV. The fission cross section is calculated for $$^{197}$$Au, $$^{209}$$Bi and $$^{238}$$U and compared with experiments. The calculation predicts fairly well the experimental values. The mass and charge distribution is calculated for $$^{208}$$Pb and $$^{232}$$Th at 1.6-GeV and 190-MeV proton incident energy, respectively.

71 (Records 1-20 displayed on this page)