Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ueki, Taro
Nuclear Science and Engineering, 194(6), p.422 - 432, 2020/06
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)In Monte Carlo criticality calculation, the convergence-in-distribution check of the sample mean of tallies can be approached in terms of the influence range of autocorrelation. In this context, it is necessary to evaluate the attenuation of autocorrelation coefficients over lags. However, in just one replica of calculation, it is difficult to accurately estimate small ACCs at large lags because of the comparability with statistical uncertainty. This paper proposes a method to overcome such an issue. Its essential component is the transformation of a standardized time series of tallies so that the resulting series asymptotically converges in distribution to Brownian motion. The convergence-in-distribution check is constructed based on the independent increment property of Brownian motion. The judgment criterion is set by way of the spectral analysis of fractional Brownian motion. Numerical results are demonstrated for extreme and standard types of criticality calculation.
Ueki, Taro
Nuclear Science and Engineering, 193(7), p.776 - 789, 2019/07
Times Cited Count：5 Percentile：48.18(Nuclear Science & Technology)It is known that the convergence of standardized time series (STS) to Brownian bridge yields standard deviation estimators of the sample mean of correlated Monte Carlo tallies. In this work, a difference scheme based on a stochastic differential equation is applied to STS in order to obtain a new functional statistic (NFS) that converges to Brownian motion (BM). As a result, statistical error estimation improves twofold. First, the application of orthonormal weighting to NFS yields a new set of asymptotically unbiased standard deviation estimators of sample mean. It is not necessary to store tallies once the updating of estimator computation is finished at each generation. Second, it becomes possible to assess the convergence of sample mean in an assumption-free manner by way of the comparison of power spectra of NFS and BM. The methodology is demonstrated for three different types of problems encountered in Monte Carlo criticality calculation.
Ueki, Taro
Proceedings of International Conference on Mathematics & Computational Methods Applied to Nuclear Science & Engineering (M&C 2017) (USB Flash Drive), 6 Pages, 2017/04
In Monte Carlo criticality calculation, the formation of a confidence interval is based on the central limit theorem for a series of tallies from generations in equilibrium. A fundamental assertion of the theorem is the convergence in distribution (CID) of an interpolated standardized time series (ISTS) of tallies. This article reports a spectral analysis approach to ISTS in order to assess the convergence of tallies in terms of CID. Numerical results are demonstrated for a preliminary model of uranium-concrete debris.
Tanaka, Masaaki; Miyake, Yasuhiro*
Mechanical Engineering Journal (Internet), 2(5), p.15-00134_1 - 15-00134_20, 2015/10
In this study, numerical simulation for the water experiment of a T-junction piping system (T-pipe) was carried out to validate the MUGTHES and to investigate the relation between the mechanism of temperature fluctuation generation and the unsteady motion of large eddy structures. In the numerical simulation, the large eddy simulation (LES) approach with standard Smagorinsky model was employed as eddy viscosity model to simulate large scale eddy motion in the T-pipe. As for uncertainty quantification in the validation process, the modified method of the Grid Convergence Index (GCI) estimation based on the least squire version could successfully quantify uncertainty. Through the numerical simulations, it could be found that the thermal mixing phenomena in the T-pipe were caused by the mutual interaction of the necklace-shaped vortex around the wake from the front of the branch jet, the horseshoe-shaped vortex and the Karman's vortex motions in the wake.
Nuclear Code Evaluation Special Committee of Nuclear Code Research Committee
JAERI-Tech 2003-078, 107 Pages, 2003/11
JAERI-Tech-2003-078.pdf:6.18MB
no abstracts in English
Nomura, Yasushi; Takada, Tomoyuki; Kadotani, Hiroyuki*; Kuroishi, Takeshi
JAERI-Tech 2003-020, 88 Pages, 2003/03
JAERI-Tech-2003-020.pdf:4.31MB
no abstracts in English
Honda, Mitsuru*; Honda, Yasuko*
Astrophysical Journal, 569(1, Part2), p.L39 - L42, 2002/04
Times Cited Count：24 Percentile：53.25(Astronomy & Astrophysics)no abstracts in English
Nuclear Code Evaluation Special Committee of Nuclear Code Research Committee
JAERI-Review 2002-003, 97 Pages, 2002/03
JAERI-Review-2002-003.pdf:8.64MB
no abstracts in English
Miyoshi, Yoshinori; Yamamoto, Toshihiro
Transactions of the American Nuclear Society, 87, p.149 - 150, 2002/00
no abstracts in English
Ikegami, Masanori*
Proceedings of 23rd Linear Accelerator Meeting in Japan, p.390 - 392, 1998/00
no abstracts in English
Yamanishi, Toshihiko; Okuno, Kenji
JAERI-Data/Code 96-028, 32 Pages, 1996/09
JAERI-Data-Code-96-028.pdf:0.89MB
no abstracts in English
; *
Journal of Nuclear Science and Technology, 33(2), p.101 - 109, 1996/02
Times Cited Count：9 Percentile：62.03(Nuclear Science & Technology)no abstracts in English
; C.A.Brebbia*
Kyokai Yosoho Kenkyukai BEM, Tekunoroji, Konfarensu Rombunshu, p.59 - 64, 1993/06
no abstracts in English
Sakamoto, Keishi; *; Kishimoto, Yasuaki; Kawasaki, S.*; Musyoki, S.*; *; *; Ishizuka, H.*;
Physical Review Letters, 70(4), p.441 - 444, 1993/01
Times Cited Count：11 Percentile：63.96(Physics, Multidisciplinary)no abstracts in English
*; Sakamoto, Keishi; *; Musyoki, S.*; *; Ishizuka, H.*; Nagashima, Takashi; Kawasaki, S.*;
JAERI-M 92-109, 68 Pages, 1992/08
no abstracts in English
; C.A.Brebbia*
Engineering Analysis with Boundary Elements, 10, p.345 - 352, 1992/00
Times Cited Count：9 Percentile：73.03(Engineering, Multidisciplinary)no abstracts in English
Sawamura, Masaru; Okubo, Makio; ; Minehara, Eisuke; Sugimoto, Masayoshi; *; Kawarasaki, Yuki; *
Proc. of the 14th Linear Accelerator Meeting in Japan, p.29 - 31, 1989/09
no abstracts in English
