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Fan Type Inducer for a Centrifugal Pump by Wire Arc Additive Manufacturing and Machining
Shinichiro Ejiri 한국유체기계학회 2023 International journal of fluid machinery and syste Vol.16 No.2
The wire arc additive manufacturing (WAAM) is one of the metal additive manufacturing technologies. WAAM can be additive manufactured to existing parts, and when combined with machining, has a high affinity for the fabrication of blades, which are important parts of turbomachinery. However, almost all related research has been limited to the fabrication of parts such as turbine blade or propeller while investigations have not been conducted by incorporating the fabricated parts into turbomachinery. In this study, a fan type inducer made of stainless steel was developed using WAAM and machining. The developed inducer was installed to a centrifugal pump, and pump performance tests were conducted to investigate the advantage of this fabrication process to turbomachinery.
Neutrinoless double beta decay and neutrino mass
Vergados, J. D.,Ejiri, H.,Š,imkovic, F. World Scientific 2016 International Journal of Modern Physics E Vol.25 No.11
<P>The observation of neutrinoless double beta decay (DBD) will have important consequences. First it will signal that lepton number is not conserved and the neutrinos are Majorana particles. Second, it represents our best hope for determining the absolute neutrino mass scale at the level of a few tens of meV. To achieve the last goal, however, certain hurdles have to be overcome involving particle, nuclear and experimental physics. Particle physics is important since it provides the mechanisms for neutrinoless DBD. In this review, we emphasize the light neutrino mass mechanism. Nuclear physics is important for extracting the useful information from the data. One must accurately evaluate the relevant nuclear matrix elements (NMEs), a formidable task. To this end, we review the recently developed sophisticated nuclear structure approaches, employing different methods and techniques of calculation. We also examine the question of quenching of the axial vector coupling constant, which may have important consequences on the size of the NMEs. From an experimental point of view it is challenging, since the life times are extremely long and one has to fight against formidable backgrounds. One needs large isotopically enriched sources and detectors with good energy resolution and very low background.</P>
Shiu, S. H.,Kohri, H.,Chang, W. C.,Ahn, D. S.,Ahn, J. K.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Gohn, W.,Hicks, K.,Hotta, T.,Hwang, S. H.,Imai, K.,Ishikawa, T.,Joo, American Physical Society 2018 Physical Review C Vol.97 No.1
<P>We report the measurement of the gamma p -> K+Lambda and gamma p -> K+Sigma(0) reactions at SPring-8. The differential cross sections and photon-beam asymmetries are measured at forward K+ production angles using linearly polarized tagged-photon beams in the range of E-gamma = 1.5-3.0 GeV. With increasing photon energy, the cross sections for both gamma p -> K+Lambda and gamma p -> K+Sigma(0) reactions decrease slowly. Distinct narrow structures in the production cross section have not been found at E gamma = 1.5-3.0 GeV. The forward peaking in the angular distributions of cross sections, a characteristic feature of t-channel exchange, is observed for the production of Lambda in the whole observed energy range. A lack of similar feature for Sigma(0) production reflects a less dominant role of t-channel contribution in this channel. The photon-beam asymmetries remain positive for both reactions, suggesting the dominance of K* exchange in the t channel. These asymmetries increase gradually with the photon energy, and have a maximum value of +0.6 for both reactions. Comparison with theoretical predictions based on the Regge trajectory in the t channel and the contributions of nucleon resonances indicates the major role of t-channel contributions as well as non-negligible effects of nucleon resonances in accounting for the reaction mechanism of hyperon photoproduction in this photon energy regime.</P>
Extension of the operational regime of the LHD towards a deuterium experiment
Takeiri, Y.,Morisaki, T.,Osakabe, M.,Yokoyama, M.,Sakakibara, S.,Takahashi, H.,Nakamura, Y.,Oishi, T.,Motojima, G.,Murakami, S.,Ito, K.,Ejiri, A.,Imagawa, S.,Inagaki, S.,Isobe, M.,Kubo, S.,Masamune, S IOP 2017 Nuclear fusion. Fusion nucléaire. &n.Illiga Vol.57 No.10
<P>As the finalization of a hydrogen experiment towards the deuterium phase, the exploration of the best performance of hydrogen plasma was intensively performed in the large helical device. High ion and electron temperatures, <I>T</I> <SUB>i</SUB> and <I>T</I> <SUB>e</SUB>, of more than 6 keV were simultaneously achieved by superimposing high-power electron cyclotron resonance heating onneutral beam injection (NBI) heated plasma. Although flattening of the ion temperature profile in the core region was observed during the discharges, one could avoid degradation by increasing the electron density. Another key parameter to present plasma performance is an averaged beta value <img ALIGN='MIDDLE' ALT='$\left\langle \beta \right\rangle $ ' SRC='http://ej.iop.org/images/0029-5515/57/10/102023/nfaa7fc2ieqn001.gif'/>. The high <img ALIGN='MIDDLE' ALT='$\left\langle \beta \right\rangle $ ' SRC='http://ej.iop.org/images/0029-5515/57/10/102023/nfaa7fc2ieqn002.gif'/> regime around 4% was extended to an order of magnitude lower than the earlier collisional regime. Impurity behaviour in hydrogen discharges with NBI heating was also classified with a wide range of edge plasma parameters. The existence of a no impurity accumulation regime, where the high performance plasma is maintained with high power heating >10 MW, was identified. Wide parameter scan experiments suggest that the toroidal rotation and the turbulence are the candidates for expelling impurities from the core region.</P>
Kohri, H.,Wang, S. Y.,Shiu, S. H.,Chang, W. C.,Yanai, Y.,Ahn, D. S.,Ahn, J. K.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Gohn, W.,Hicks, K.,Hosaka, A.,Hotta, T.,Hwang, American Physical Society 2018 Physical review. C Vol.97 No.1
<P>Differential cross sections and photon-beam asymmetries for the (gamma) over right arrowp -> pi(+) n reaction have been measured for 0.6 < cos theta(pi) < 1 and E-gamma = 1.5-2.95 GeV at SPring-8/LEPS. The cross sections monotonically decrease as the photon beam energy increases for 0.6 < cos theta(pi) < 0.9. However, the energy dependence of the cross sections for 0.9 < cos theta(pi) < 1 and E-gamma = 1.5-2.2 GeV (W = 1.9-2.2 GeV) is different, which may be due to a nucleon or Delta resonance. The present cross sections agree well with the previous cross sections measured by other groups and show forward peaking, suggesting significant t-channel contributions in this kinematical region. The asymmetries are found to be positive, which can be explained by rho exchange in the t channel. Large positive asymmetries in the small-vertical bar t vertical bar region, where the rho-exchange contribution becomes small, could be explained by introducing p-exchange interference with the s channel.</P>
Kohri, H.,Shiu, S. H.,Chang, W. C.,Yanai, Y.,Ahn, D. S.,Ahn, J. K.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Gohn, W.,Hicks, K.,Hosaka, A.,Hotta, T.,Hwang, S. H.,Imai, American Physical Society 2018 Physical Review Letters Vol.120 No.20
<P>Differential cross sections and photon-beam asymmetries for the gamma(->)p -> Pi(-)Delta(++)(1232) reaction have been measured for 0.7 < cos Theta(c.m.)(Pi) < 1 and E-gamma= 1.5-2.95 GeV at SPring-8/LEPS. The first-ever high statistics cross-section data are obtained in this kinematical region, and the asymmetry data for 1.5 < E-gamma(GeV) < 2.8 are obtained for the first time. This reaction has a unique feature for studying the production mechanisms of a pure uu quark pair in the final state from the proton. Although there is no distinct peak structure in the cross sections, a non-negligible excess over the theoretical predictions is observed at E-gamma= 1.5-1.8 GeV. The asymmetries are found to be negative in most of the present kinematical regions, suggesting the dominance of n exchange in the t channel. The negative asymmetries at forward meson production angles are different from the asymmetries previously measured for the photoproduction reactions producing a dd(-) or an ss quark pair in the final state. Advanced theoretical models introducing nucleon resonances and additional unnatural-parity exchanges are needed to reproduce the present data.</P>
Interference Effect betweenϕandΛ(1520)Production Channels in theγp→K+K−pReaction near Threshold
Ryu, S. Y.,Ahn, J. K.,Nakano, T.,Ahn, D. S.,Ajimura, S.,Akimune, H.,Asano, Y.,Chang, W. C.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Hasegawa, S.,Hicks, K.,Horie, K.,Ho American Physical Society 2016 Physical Review Letters Vol.116 No.23
<P>The phi-Lambda(1520) interference effect in the gamma p -> K(+)K(-)p reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between phi and Lambda(1520) production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when K+K- pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the root s = 2.1 GeV bump structure in forward differential cross sections for phi photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.</P>