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Onishi, Hiroaki; Miyashita, Seiji*
JPS Conference Proceedings (Internet), 38, p.011157_1 - 011157_6, 2023/05
Onishi, Hiroaki; Miyashita, Seiji*
Physical Review B, 106(13), p.134436_1 - 134436_13, 2022/10
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)Sakai, Toru; Hijii, Keigo*; Okubo, Susumu*; Ota, Hitoshi*; Nakano, Hiroki*; Miyashita, Seiji*
Applied Magnetic Resonance, 46(9), p.997 - 1002, 2015/09
Times Cited Count：1 Percentile：6.49(Physics, Atomic, Molecular & Chemical)The S=1/2 kagome-lattice antiferromagnet is investigated by the numerical diagonalization of 18-spin finite-size cluster. The matrix elements proportional to the intensity of the singlet-triplet ESR transition are calculated in the presence of the Dzyaloshinsky-Moriya interaction. Some angle-dependent selection rules is also proposed.
Onishi, Hiroaki; Miyashita, Seiji*
Physical Review B, 90(22), p.224426_1 - 224426_11, 2014/12
Times Cited Count：1 Percentile：4.65(Materials Science, Multidisciplinary)
Sn superconducting strands for ITER toroidal field coilsNabara, Yoshihiro; Nunoya, Yoshihiko; Isono, Takaaki; Hamada, Kazuya; Uno, Yasuhiro; Takahashi, Yoshikazu; Nakajima, Hideo; Tsuzuku, Seiji*; Tagawa, Kohei*; Miyashita, Katsumi*; et al.
Teion Kogaku, 47(3), p.140 - 146, 2012/03
no abstracts in English
Kubo, Shinji; Kasahara, Seiji; Sato, Hiroyuki; Imai, Yoshiyuki; Iwatsuki, Jin; Tanaka, Nobuyuki; Miyashita, Reiko*; Tago, Yasuhiro*; Onuki, Kaoru
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/12
A stable hydrogen production via the IS process is relatively difficult because of the unique characteristics of the closed-cycle condition involved. This issue is therefore a high targeted priority when industrializing the process as feasible in a chemical plant. In system of IS process coupled with helium gas heat source, a process control method to maintain mass balance of the process was devised. The method is equipped with measurements of Bunsen reaction composition and allocation of heat for the O
and H production sections in strict proportion. Via computer simulation for closed-cycle and fully multi-section driven by high-temperature helium gas, the system worked automatically to maintain stoichiometric production ratio in response to shifts of helium gas conditions.
Kubo, Shinji; Nakajima, Hayato; Imai, Yoshiyuki; Kasahara, Seiji; Tanaka, Nobuyuki; Okuda, Hiroyuki; Miyashita, Reiko*; Onuki, Kaoru
Proceedings of 17th World Hydrogen Energy Conference (WHEC 2008) (CD-ROM), 4 Pages, 2008/06
A new technique was developed to estimate compositions of Bunsen reaction solution in liquid-liquid phase separation which was targeted on the two solutions in phase equilibrium. In this technique, just two densities measured in the two solution are employed to estimate compositions of two solutions consisting of HI, HSO
, I, HO. The fundamental equations underlying this estimation is relations between densities and compositions. To formulate the relations, densities of simulated Bunsen reaction solutions were measured and regression expressions were formulated. Moreover, relational equations for both phases were set up from measured values by the regression procedure. Through estimations of both compositions from both densities, the calculated values are approximately consistent with titrated values. Because of easily and simply execution, this technique is useful for practical use, especially for plant operation and equipment design.
Onishi, Hiroaki; Miyashita, Seiji*
Physica B; Condensed Matter, 329-333(2), p.874 - 875, 2003/05
Times Cited Count：0 Percentile：0(Physics, Condensed Matter)We investigate a one-dimensional 
antiferromagnetic Heisenberg model coupled to quantum lattice vibration by a quantum Monte Carlo method. For heavy mass, the lattice fluctuation can be regarded to be adiabatic and the system dimerizes at low temperature. On the other hand, for light mass, the lattice takes a uniform configuration on the thermal average and magnetic properties coincide with those of the uniform lattice system. These phenomena can be understood from the difference of the time scale of the motion between the spin and the lattice.
Onishi, Hiroaki; Miyashita, Seiji*
Journal of the Physical Society of Japan, 72(2), p.392 - 398, 2003/02
Times Cited Count：5 Percentile：38.86(Physics, Multidisciplinary)We investigate a one-dimensional antiferromagnetic Heisenberg model coupled to quantum lattice vibration using a quantum Monte Carlo method. We study the ground-state lattice fluctuation where the system shows a characteristic structure factor. We also study the mass dependence of magnetic properties such as the magnetic susceptibility and the magnetic excitation spectrum. For heavy mass, the system shows the same behavior as the case of classical lattice vibration. On the other hand, for light mass, magnetic properties coincide with those of the static uniform chain. We investigate the physical mechanism of this behavior and propose the picture of quantum narrowing.
Kubo, Shinji; Ohashi, Hirofumi; Kanagawa, Akihiro; Kasahara, Seiji; Imai, Yoshiyuki; Fukui, Hiroshi*; Nishibayashi, Toshiki*; Shimazaki, Masanori*; Miyashita, Reiko*; Tago, Yasuhiro*; et al.
no journal, ,
For a stable hydrogen production, essential problems with the closed-cycle operation are declared, and the cycle can ensure these are retained in a steady state in case the H production rate, O production rate and HO supply rate have equivalent values. Process control methods used to maintain the mass balance of the process were devised, involving the installation of accumulators for the total system, techniques to maintain the Bunsen reaction composition and so on. For the plant operation, both controlled and manipulated variables were determined, while computer simulation and the bench scale H production test were used to confirm control methods. For closed cycle operation for water splitting driven by helium gas heat, the method is discussed to allocate heat for the O and H production sections in strict proportion. Finally, the use of computer simulation for the O production system allowed the key to maintaining heat balance within a cascade heat absorption system to be confirmed.
Hijii, Keigo*; Sakai, Toru; Miyashita, Seiji*; Ota, Hitoshi*
no journal, ,
We numerically investigated the dynamical susceptibility of the S=1/2 trimerized quantum spin chain. In order to solve the mechanism of the special feature, which is characteristic of the composite spins different from the single S=3/2, observed in the previous high frequency ESR measurement by Prof. Ajiro, we will report the numerical result of the external field dependence and the temperature dependence of the dynamical susceptibility.
Onishi, Hiroaki; Miyashita, Seiji*
no journal, ,
no abstracts in English
Onishi, Hiroaki; Miyashita, Seiji*
no journal, ,
no abstracts in English
