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Titarenko, Yu. E.*; Batyaev, V. F.*; Pavlov, K. V.*; Titarenko, A. Yu.*; Malinovskiy, S. V.*; Rogov, V. I.*; Zhivun, V. M.*; Kulevoy, T. V.*; Chauzova, M. V.*; Khalikov, R. S.*; et al.

Nuclear Instruments and Methods in Physics Research A, 1026, p.166151_1 - 166151_9, 2022/03

Times Cited Count：0 Percentile：0.02(Instruments & Instrumentation)The paper presents the Hg production cross-sections measured by the direct gamma-spectrometry technique in the samples of lead enriched with isotopes 206, 207 and 208, as well as in the samples of natural lead and bismuth, irradiated by protons of 11 energies in the range from 0.04 to 2.6 GeV. The obtained experimental results are compared with the previous measurements, with the TENDL-2019 data-library evaluations and the simulated data by means of the high-energy transport codes MCNP6.1 (CEM03.03), PHITS (INCL4.6/GEM), Geant4 (INCL++/ABLA) and the nuclear reaction code TALYS.

Kawano, Toshihiko*; Cho, Y. S.*; Dimitriou, P.*; Filipescu, D.*; Iwamoto, Nobuyuki; Plujko, V.*; Tao, X.*; Utsunomiya, Hiroaki*; Varlamov, V.*; Xu, R.*; et al.

Nuclear Data Sheets, 163, p.109 - 162, 2020/01

Times Cited Count：53 Percentile：99.67(Physics, Nuclear)Nishida, Akemi; Matsubara, Hitoshi; Tian, R.; Hazama, Osamu; Suzuki, Yoshio; Araya, Fumimasa; Nakajima, Norihiro; Tani, Masayuki; Kondo, Makoto

Nihon Genshiryoku Gakkai Wabun Rombunshi, 6(3), p.376 - 382, 2007/09

Unexpected accidents such as oil-tank fires caused by the earthquake and breakage of pipes of nuclear plants have occurred over the past several years. Higher reliability is thus now increasingly expected to maintain the safety of infrastructures. We have been intensely focused on the construction of an analysis system called the "three-dimensional virtual vibration testbed," which is a numerical simulation system for a nuclear plant which considers the interconnection of machines, pipes, buildings, and their foundations under real operating conditions. In this paper, the "part-wise analysis method" is proposed in which each structural component is treated independently and analyzed as an assembly structure. Further, the system configurations in a parallel distribution environment are described. This study shows one of the successful examples of the application of this method to a nuclear-plant cooling system that has tens of millions of degrees of freedom.

Tian, R.; Yagawa, Genki

International Journal for Numerical Methods in Engineering, 71(4), p.473 - 503, 2007/07

Times Cited Count：16 Percentile：69.91(Engineering, Multidisciplinary)Rewards of using non-matching meshes are great in many aspects: sub-meshing a complex structure in a sub-structure-wise manner separately; selective local refinement; unlimited scalability guarantee for generating meshes, etc. However, when meshes do not match, a gluing algorithm is required to enforce inter-domain continuity. The non-matching mesh issue is avoidable or does not exist in a node-based or meshless discretization in meshless methods. Motivated by this, a gluing algorithm is developed based on meshless interpolation. The gluing is accomplished by continuous trial and test functions across non-matching meshes constructed using nodes only. Compared with Lagrange multiplier gluing - one of the most common approaches - the current algorithm has two significant benefits: (1) easier implementation in any dimension and (2) positive definite banded system matrices, not acting against equation solvers, and hence better suited for large-scale finite element analysis.

Tian, R.; Yagawa, Genki

International Journal for Numerical Methods in Engineering, 69(4), p.837 - 858, 2007/01

Times Cited Count：19 Percentile：73.72(Engineering, Multidisciplinary)A simplification of the 1984 Allman triangle is presented. It is found that this old element takes a typical form of the partition of unity approximation. The Allman's rotation presented in the partition of unity form offers merits and convenience in formulation and practical applications. The stiffness matrix of the 1984 Allman triangle, which is originally computed from the linear strain triangular element, can be obtained instead in a cheaper way from that of the constant strain triangular element. The constraint of the rotational terms during essential boundary treatment, which remains equivocal and ambiguous, is understood to be mandatory. The partition of unity notion enables a straightforward extension of the Allman's rotational dof to meshfree approximations.

Tian, R.; Matsubara, Hitoshi; Yagawa, Genki

International Journal for Numerical Methods in Engineering, 68(12), p.1209 - 1231, 2006/12

Times Cited Count：30 Percentile：79.9(Engineering, Multidisciplinary)Tetrahedral elements are indispensable to complex finite element structural analysis. Two existing and two newly developed advanced 4-node tetrahedrons are studied in this paper. The existing elements that use complicated displacement fields are significantly simplified. The spurious zero-energy modes typical of all these elements are identified to be rigid-body-alike modes and are found to be naturally suppressible, making it possible to avoid any stabilization techniques and unknown parameters in formulation. Through the simplified form, we connect these four tetrahedrons and view them in a general framework of the partition-of-unity-based approximation. This general view allows us to reveal many promising features of the newly developed tetrahedrons by comparing them with their existing counterparts: the newly developed tetrahedrons have straightforward formulation.

Hazama, Osamu; Suzuki, Yoshio; Matsubara, Hitoshi; Tian, R.; Nishida, Akemi; Tani, Masayuki; Nakajima, Norihiro

Proceedings of 7th MpCCI User Forum, p.132 - 136, 2006/00

Nuclear power plants are large in scale and functionally very complex structures. For safety precautions, they are maintained under very strict rules. Yet, no controlled experiments are possible to deal with full-scale nuclear reactors and its cooling systems in its entirety. In order to maintain the safety of these nuclear power plants against extra-large earthquakes and aging, Japan Atomic Energy Agency (JAEA) is currently constructing a fully three-dimensional virtual earthquake testbed on the ITBL Grid infrastructure. Currently, we have developed a high-performance finite element elastostatic simulation system based on component and part-wise assembly. Using the program, we were able to construct a finite element model of an experimental high-temperature gas reactor (HTGR) called HTTR, or High Temperature engineering Test Reactor.

Tian, R.; Nakajima, Norihiro; Yagawa, Genki

Keisan Kogaku Koenkai Rombunshu, 10(1), p.393 - 396, 2005/05

A known problem of partition of unity-based generalized finite element methods (referred to as GFEM) is the linear dependence problem, which leads to singular global (stiffness) matrices. Thus far, attempts to eliminate the linear dependence problem have been unsuccessful. Numerical experiments are carried out among several GFEMs to investigate the problem. Based on the numerical experiments, simple but effective approaches to eliminating the linear dependence problem are suggested.

Tian, R.; Nakajima, Norihiro; Yagawa, Genki

Keisan Kogaku Koenkai Rombunshu, 10(1), p.397 - 400, 2005/05

An attempt is made to treat boundary conditions in EFGM through only nodal arrangements. One of major merits of the proposed nodal arrangement scheme is its straightforwardness in implementation. The accuracy of this nodal arrangement boundary treatment and its influence on convergence are assessed by comparing with the Lagrange multiplier and penalty methods using one- and two- dimensional problems. The nodal arrangement scheme shows a same performance as the Lagrange multiplier and penalty methods in the one-dimensional tests, but it evidently outperforms the penalty method in the two-dimensional tests.

Chung, J.-H.*; Proffen, T.*; Shamoto, Shinichi; Ghorayeb, A. M.*; Croguennec, L.*; Tian, W.*; Sales, B. C.*; Jin, R.*; Mandrus, D.*; Egami, Takeshi*

Physical Review B, 71(6), p.064410_1 - 064410_11, 2005/02

Times Cited Count：72 Percentile：89.93(Materials Science, Multidisciplinary)LiNiO (S=1/2) forms a triangular lattice with the possible magnetic frustration, but the exact state of spin correlation has not yet been known. While there is no signature of long-range Jahn-Teller distortion, local JT distortion has been suspected. We have performed neutron diffraction and atomic pair-density function analyses up to unprecedented large distances to discover a number of unusual features, such as anomalous peak broadening, local JT distortion, sharp oxygen-oxygen distance correlations, and inverted temperature dependence of medium range correlation. These observations are best explained by local orbital ordering of Ni ions into three sublattices. This orbital ordering, however, cannot develop into long-range order because of the strain field it generates, and domains of about 10 nm in size are formed. Domains are susceptible to random pinning by impurities ssite disorderd resulting in the loss of structural long-range order. We suggest that this local orbital ordering is the basis for the complex magnetic properties observed in this compound.

Matsubara, Hitoshi; Minami, Takahiro; Hazama, Osamu; Nishida, Akemi; Tian, R.; Nakajima, Norihiro; Tani, Masayuki

no journal, ,

A nuclear power plant is made up of numerous components. In previous techniques, structural analyses of entire nuclear power plant have not been achieved because it is assumed to be united structure. In this work, through our new model approach called the assembled-structure analysis, simulation of an entire nuclear power plant by assembling of individual components was made possible.

Tian, R.; Miyazaki, Akemi; Matsubara, Hitoshi; Nakajima, Norihiro; Tani, Masayuki

no journal, ,

A nuclear power plant is made up of numerous components that are interconnected to each other. Upon external load, they act in a certain interactive way to bear the external load. Therefore, it is an important issue to understand the interaction effect and integrated behaviors of these components. At the current stage, a nuclear power plant is assumed to be a unified structure, and hence it is impossible to evaluate the interaction effects among these components. We have recently established a new approach called assembled structure analysis. In this talk, we will give an introduction of the outline of the entire nuclear power plant simulation system and the fundamental system design of the connection effect evaluation methods.

Miyazaki, Akemi; Tian, R.; Matsubara, Hitoshi; Nakajima, Norihiro; Tani, Masayuki

no journal, ,

A nuclear power plant is made up of numerous components that are interconnected to each other. Upon external load, they act in a certain interactive way to bear the external load. Therefore, it is an important issue to understand the interaction effect and integrated behaviors of these components. At the current stage, a nuclear power plant is assumed to be a unified structure, and hence it is impossible to evaluate the interaction effects among these components. We have recently established a new approach called assembled structure analysis. In this presentation, we will demonstrate the static simulation results of stresses/strain of the cooling system of the nuclear power plant, and show the great possibility of modeling the nuclear power plant in entire in near future.

Suzuki, Yoshio; Kushida, Noriyuki; Yamagishi, Nobuhiro; Minami, Takahiro; Matsumoto, Nobuko; Nakajima, Kohei; Nishida, Akemi; Matsubara, Hitoshi; Tian, R.; Hazama, Osamu; et al.

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no abstracts in English

Tian, R.

no journal, ,

In many situations, using a non-matching mesh is convenient even indispensable. However, conventional finite element interpolation fails when meshes do not match and a gluing algorithm is required to enforce inter-mesh continuity. In this paper, a gluing algorithm is developed based on a meshless interpolation. A continuous function is constructed across two non-matching and discontinuous meshes by a meshless interpolation using nodes from both sides to perform the stitch-up. The original meshes are used for such purposes as the integration of weak form and construction of mass matrix in dynamic analyses etc. In this study, a compactly supported radial basis function interpolation is employed. The gluing algorithm developed is tested in static and wave propagation problems. Some numerical evaluation in three dimensions are also provided. Through the numerical samples, superior performance in both accuracy and convergence over traditional approaches are demonstrated. Compared with other gluing algorithms, for example, the Lagrange multipliers, the current algorithm offers (1) straightforward implementation in any dimensions, and (2) banded, positive and definite system matrices, posing no difficulty in equation solvers.

Miyazaki, Akemi; Suzuki, Yoshio; Matsubara, Hitoshi; Tian, R.; Hazama, Osamu; Tani, Masayuki; Nakajima, Norihiro

no journal, ,

Nuclear power plants are large-scale complicated structures comprising many components. The connections between these components are one of the weakest parts of a nuclear power plant. Further, these parts retain many unknown characteristics with respect to the dynamic properties of the connections. To apply a 3D virtual plant vibration simulator to the large-scale structural analysis of a nuclear power plant, a technology to consider the structure as an assemblage of components and to enable whole scale analysis of an extra-large plant by considering the interaction between its parts was developed and implemented on a prototype system on a grid environment. In this report, a system construction on a grid environment of an assembly structure is analyzed; further, an example of an application for the static structure analysis of a cooling system of a high temperature engineering test reactor (HTTR) of The Oarai Research and Development Center, JAEA is shown.

Nakajima, Norihiro; Suzuki, Yoshio; Kushida, Noriyuki; Matsubara, Hitoshi; Nakajima, Kohei; Tani, Masayuki; Miyazaki, Akemi; Tian, R.; Hazama, Osamu

no journal, ,

no abstracts in English