Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 78

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

JAEA Reports

Preparation of Computational Science Simulation Code SPLICE for Laser Manufacturing Process; Research activities on FY2019

Muramatsu, Toshiharu

JAEA-Research 2019-008, 111 Pages, 2019/11

JAEA-Research-2019-008.pdf:8.64MB

A general-purpose three-dimensional thermohydraulics numerical simulation code SPLICE (residual Stress control using Phenomenological modeling for Laser welding repair process In Computational Environment) was designed to deal with gas-liquid-solid consolidated incompressible viscous flows with a phase change process in various laser applications. Main features of the SPLICE code are as follows: (1) A multi-scale model is used to simulate complicated phenomena, such as welding to solidification of metal materials, thermal and mechanical interactions among gas, liquid and solid phases, etc., (2) SPLICE code is applicable for the evaluation of welding, cutting, piercing, coating, additive manufacturing, etc. and (3) A graphic user interface (GUI) is prepared for users to easy utilization of the SPLICE code. This report describes the details of the mathematics, physics, numerics, sample applications of the SPLICE code.

Journal Articles

Provision of laser irradiation conditions for melting and solidification processes using computational science simulation code SPLICE

Muramatsu, Toshiharu

Sumato Purosesu Gakkai-Shi, 8(1), p.4 - 8, 2019/01

no abstracts in English

Journal Articles

Interpretation of thermal desorption spectra of hydrogen from aluminum using numerical simulation

Ebihara, Kenichi; Yamaguchi, Masatake; Tsuru, Tomohito; Itakura, Mitsuhiro

Keikinzoku, 68(11), p.596 - 602, 2018/11

Hydrogen embrittlement (HE) is considered as one cause of stress corrosion cracking. HE is a serious problem in the development of high strength aluminum alloy as with steels. For understanding HE, it is inevitable to know hydrogen trapping states in the alloys and it can be identified using thermal desorption spectrometry of H. In this study, we numerically simulated thermal desorption spectra of hydrogen in aluminum for a cylindrical and a plate specimens and interpreted the desorption peaks included in them on the basis of the trap site concentration and the trap energy. As a result, we found that the peak at the lowest-temperature side can result from grain boundaries and confirmed that the reported interpretation for other peaks is reasonable. We also obtained the result showing the possibility that the trap site concentration of defects changes during heating the specimens. This result may give a suggestion for the interpretation of temperature desorption spectra of steels.

Journal Articles

Study on simulation of thermal desorption spectra for a tempered martensitic steel with vacancies induced by hydrogen and strain

Ebihara, Kenichi; Saito, Kei*; Takai, Kenichi*

"Suiso Zeika No Kihon Yoin To Tokusei Hyoka" Kenkyukai Hokokusho, p.57 - 61, 2018/09

no abstracts in English

Journal Articles

Numerical simulation of hydrogen thermal desorption profile under assumption of two kinds of trap sites for tempered martensitic steel

Tsuchida, Yutaka*; Ebihara, Kenichi

Tetsu To Hagane, 103(11), p.653 - 659, 2017/11

 Times Cited Count:0 Percentile:100(Metallurgy & Metallurgical Engineering)

A single peak in thermal desorption profiles of hydrogen, which are measured in low-temperature thermal desorption spectrometry (L-TDS) for a very thin plate specimen of tempered martensitic steel, was reproduced successfully by the superposition of two Gaussian distributions. Then, the parameters concerning the detrapping rate constants for both peaks, which are trap energy and pre-exponential factor, were calculated using the Choo-Lee plot. We confirmed that Kissinger model incorporating the obtained parameters could simulate the two peaks. In addition, we reproduced the single peak well using the reaction-diffusion equation incorporating the obtained parameters and the appropriate trap site concentration. From the results, we interpreted that the one peak corresponds to dislocation and the other to grain-boundary.

Journal Articles

Report of lecture course for "Guideline for Credibility Assessment of Nuclear Simulations 2015"

Tanaka, Masaaki

Nihon Genshiryoku Gakkai Keisan Kagaku Gijutsu Bukai Nyusu Reta (Internet), (27), p.9 - 15, 2017/03

In this report, the outline of the contents in the lecture course for "Guideline for Credibility Assessment of Nuclear Simulations 2015" published in June, 2016 from the Atomic Energy Society of Japan (AESJ) and the result of the lectures held in Tokyo and Osaka are introduced with the results of the questionnaires from the audience.

Journal Articles

Validation of measured microwave absorption and temperature change for development of a single-mode-type microwave heating thermogravimetry apparatus

Karisma, A. D.*; Hamaba, Taishu*; Fukasawa, Tomonori*; Huang, A.-N.*; Segawa, Tomoomi; Fukui, Kunihiro*

Review of Scientific Instruments, 88(2), p.024101_1 - 024101_8, 2017/02

 Times Cited Count:1 Percentile:87.78(Instruments & Instrumentation)

Microwave heating direct denitration method is used in the nuclear fuel reprocessing process. In order to develop a single-mode-type microwave heating thermogravimetry apparatus which can perform detailed analysis of the characteristics of microwave heating, the temperature dependence of microwave absorption is verified. The temperature distribution, microwave absorption efficiency, and dielectric properties of a CuO pellet that was heated by the microwave irradiation were investigated. The temperature distribution in the CuO pellet due to one-way travel of the microwave in the apparatus was accurately reproduced by a three-dimensional numerical simulation of the electromagnetic field. The numerically determined temperature dependency of the CuO absorption efficiency was found to be in very good agreement with published data.

Journal Articles

Determination of detrapping and trapping rate constants for hydrogen based on experimental thermal desorption spectra

Ebihara, Kenichi; Saito, Kei*; Takai, Kenichi*

Proceedings of 2016 International Hydrogen Conference (IHC 2016); Materials Performance in Hydrogen Environments, p.470 - 477, 2017/00

For understanding hydrogen (H) embrittlement of steels, it is necessary to infer the state that defects trap H in the steels. Thermal desorption spectra of H obtained by the thermal desorption spectrometry (TDS) are used for inferring such a state. Because the thermal desorption spectra include the influence of experimental conditions and hydrogen diffusion as well as information of the defects trapping H, it is necessary to interpret the spectra using the numerical simulation. In the presentation, we determined the detrapping and the trapping rate constants which are necessary for the simulation from the experimental spectra obtained for plate specimens which is so small that H diffusion is ignorable. Then we confirmed that the model using the obtained rate constants can simulate the spectra of larger cylindrical specimens, so that it was found that the rate constant for small specimens can be used for the simulation of the spectra for specimens of different shape or size.

Journal Articles

Study on modeling of thermal desorption spectra of hydrogen including variation of vacancy-type trap sites

Ebihara, Kenichi; Saito, Kei*; Takai, Kenichi*

"Suiso Zeika No Kihon Yoin To Tokusei Hyoka Kenkyukai Chukan Hokokukai" Shimposium Yokoshu (USB Flash Drive), p.30 - 35, 2016/09

no abstracts in English

Journal Articles

Expectations for corrosion science and technology from the viewpoint of long-term prediction

Taniguchi, Naoki

Zairyo To Kankyo, 65(9), p.363 - 364, 2016/09

no abstracts in English

Journal Articles

Numerical reproduction of hydrogen thermal desorption spectra of tempered martensitic steel based on experimental data

Ebihara, Kenichi; Saito, Kei*; Takai, Kenichi*

"Suiso Zeika No Kihon Yoin, Kaiseki To Hyoka" Shimposium Yokoshu (USB Flash Drive), p.27 - 33, 2015/09

The thermal desorption spectra which reflect the H segregation state can be obtained by heating a specimen including H at a constant rate. However, the simulation of spectra needs to extract information of the H segregation state because spectra is affected by experimental conditions and H diffusion. The detrapping activation energy E$$_a$$ and the pre-exponential factor of detraping rate constant which are simulation parameters are fixed from the data previously reported or by fitting experimental spectra. Instead, we evaluated both of them from the experimental spectra of the specimen in which the H diffusion effect can be ignored, and simulated the spectra using them. As a result, in the case of iron, we could simulate spectra better than by the previous parameters. In the case of tempered martensitic steel, we could simulate spectra by the value obtained by adjusting the evaluated p$$_0$$ along with the evaluated E$$_a$$.

Journal Articles

Benchmark analysis of thermal striping phenomena in planar triple parallel jets tests for fundamental validation of fluid-structure thermal interaction code for sodium-cooled fast reactor

Tanaka, Masaaki; Nagasawa, Kazuyoshi*

Proceedings of 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16) (USB Flash Drive), p.6650 - 6663, 2015/08

For the fundamental validation of fluid-structure thermal interaction code (MUGTHES), numerical simulations for the planar triple parallel jets tests in WAJECO and PLAJEST have been conducted as the benchmark analysis. In comparison between the numerical results and the provided experimental results, thermal mixing process and large-scale eddy structures generated in the triple jets mixing and the relation between temperature fluctuation generation and large-eddy structures were revealed. And also, the attenuation process of temperature fluctuation from the fluid to the structure was indicated.

Journal Articles

Numerical simulation of turbulent heat transfer behind a spacer with small-ribs in a subchannel

Takase, Kazuyuki

Proceedings of OECD/NEA & IAEA Workshop on Application of CFD/CMFD Codes to Nuclear Reactor Safety and Design and their Experimental Validation (CFD4NRS-5) (Internet), 11 Pages, 2014/09

When devising the thermal design of supercritical water reactors, it is necessary to develop an analysis method that correctly predicts the turbulent heat transfer characteristics in subchannels of fuel bundles. Spacers are set into the subchannels to maintain the distances between adjacent fuel rods. The turbulent heat transfer is generally enhanced by the spacers' reduction of the cross-sectional area in the subchannels. However, since the thermophysical properties of supercritical fluids drastically change in the vicinity of a pseudocritical point, the enhancement of the turbulent heat transfer depends on the thermal design. To this end, the Japan Atomic Energy Agency is developing an analysis method that will predict the thermal-hydraulic characteristics of supercritical fluids. The heat transfer calculations were performed using a newly developed code under conditions of a subchannel with a spacer. The enhancement of the turbulent heat transfer coefficient in the subchannels with spacers was analyzed numerically.

Journal Articles

Development of a meta-computing infrastructure for parallel coupled simulations

Hazama, Osamu; Nakajima, Norihiro; Hirayama, Toshio; Post, P.*; Wolf, K.*

IWACOM, P. 161, 2004/11

The numerical methods and computational hardware of today allow for studies on multi-disciplinary simulations. We have been developing an "integrated numerical simulation system" to solve coupled simulation problems under meta-computing environments. The system aims to construct a competent coupler for carrying out multi-disciplinary simulations by allowing concurrent execution of arbitrary simulation codes on different computers in parallel. The effectiveness of this system infrastructure is illustrated through its applications to fluid-structure interactive problems.

Journal Articles

Unknown characteristic frequency of a multibubble system in a sound field; Theoretical prediction and numerical verification using an improved CIP-CUP

Ida, Masato

Proceedings of 6th World Congress on Computational Mechanics in conjunction with 2nd Asian-Pacific Congress on Computational Mechanics (CD-ROM), p.1 - 11, 2004/09

The existence of the "transition frequencies" of two acoustically coupled gas bubbles has been verified by direct numerical simulation. The theory described by Ida [Phys. Lett. A 297 (2002) 210] predicted that a bubble in the double-bubble system has three transition frequencies, some of which makes the phase difference between the bubble's volume oscillation and an external sound $$pi/2$$ without accompanying resonance response of the bubble. In a more recent paper [Ida, Phys. Rev. E 67 (2003) 056617], it was suggested theoretically that one of the transition frequencies may cause the sign reversal of the secondary Bjerknes force acting between pulsating bubbles. In the present study, we employ a direct numerical simulation technique that uses the compressible Navier-Stokes equations with a surface-tension term as the governing equations to investigate the transition frequencies of two coupled bubbles. The numerical results clearly exhibit the existence of the theoretically predicted characteristic frequency.

Journal Articles

Practical integrated simulation systems for coupled numerical simulations in parallel

Hazama, Osamu; Guo, Z.

Proceedings of International Conference on Supercomputing in Nuclear Applications (SNA 2003) (CD-ROM), p.119 - 120, 2003/09

In order for the numerical simulations to reflect textquotedblleft real-worldtextquotedblright phenomena and occurrences, incorporation of multidisciplinary and multi-physics simulations considering various physical models and factors are becoming essential. However, there still exist many obstacles which inhibit such numerical simulations. For example, it is still difficult in many instances to develop satisfactory software packages which allow for such coupled simulations and such simulations will require more computational resources. A precise multi-physics simulation today will require parallel processing which again makes it a complicated process. Under the international cooperative efforts between CCSE/JAERI and Fraunhofer SCAI, a German institute, a library called the MpCCI, or Mesh-based Parallel Code Coupling Interface, has been implemented together with a library called STAMPI to couple two existing codes to develop an textquotedblleft integrated numerical simulation systemtextquotedblright intended for meta-computing environments.

Journal Articles

Development of an integrated numerical simulation infrastructure for fluid-structure coupled problems

Hazama, Osamu; Guo, Z.

Keisan Kogaku Koenkai Rombunshu, 8(2), p.759 - 760, 2003/05

no abstracts in English

Journal Articles

Present status and future prospect on System for Prediction of Environmental Emergency Dose Information, SPEEDI

Chino, Masamichi; Adachi, Takeo

Nippon Genshiryoku Gakkai-Shi, 45(5), p.296 - 301, 2003/05

no abstracts in English

Journal Articles

Dynamical matching of Josephson vortex lattice with sample edge in layered high-${it Tc}$ superconductors; Origin of the periodic oscillation of flux flow resistance

Machida, Masahiko

Physical Review Letters, 90(3), p.037001_1 - 037001_4, 2003/01

 Times Cited Count:58 Percentile:11.43(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Evaluation of power history during power burst experiments in TRACY by combination of $$gamma$$-ray and thermal neutron detectors

Yanagisawa, Hiroshi; Ono, Akio

Journal of Nuclear Science and Technology, 39(6), p.597 - 602, 2002/06

 Times Cited Count:2 Percentile:81.85(Nuclear Science & Technology)

no abstracts in English

78 (Records 1-20 displayed on this page)