106,192 research outputs found
59. Hamaguchi Osachi (1870-1931)
No full textIwao Seiichi, Sakamato Tarō, Hōgetsu Keigo, Yoshikawa Itsuji, Akiyama Terukazu, Iyanaga Teizō, Iyanaga Shōkichi, Matsubara Hideichi, Kanazawa Shizue. 59. Hamaguchi Osachi (1870-1931). In: Dictionnaire historique du Japon, volume 7, 1981. Lettre H (1) p. 37
59. Hamaguchi Osachi (1870-1931)
No full textIwao Seiichi, Sakamato Tarō, Hōgetsu Keigo, Yoshikawa Itsuji, Akiyama Terukazu, Iyanaga Teizō, Iyanaga Shōkichi, Matsubara Hideichi, Kanazawa Shizue. 59. Hamaguchi Osachi (1870-1931). In: Dictionnaire historique du Japon, volume 7, 1981. Lettre H (1) p. 37
Multi-Stage Multi-User Detection Assisted Asynchronous Fast-FH/MFSK
No full textA multi-stage Multi-User Detection (MUD) scheme designed for asynchronous fast Frequency-Hopping/Multilevel Frequency-Shift-Keying (fast-FH/MFSK) systems is proposed, in which each signal detection interval is divided into sub-intervals and the MUD is applied to each sub-interval. In our scheme the MUD exploits the explicit knowledge of the hopping addresses assigned to users. The received signal level is attenuated by a constant scaling factor, when it is deemed to be overwhelmed by multi-user interference. For the sake of preventing erroneous detection events, when communicating over frequency-selective fading channels, the scheme advocated also invokes a space diversity technique. In the investigated scenario the achievable Bit Error Rate (BER) of the proposed scheme was reduced by as much as an order of magnitude in comparison to that of a conventional MUD scheme, when transmitting over an AWGN channel. For transmission over a channel exhibiting uncorrelated frequency-domain fading, selection diversity was used for the sake of achieving a reduced BER
Wave dispersion relations in Yukawa fluids
No full textH. Ohta and S. Hamaguchi, Phys. Rev. Lett. 84, 6026, 2000The wave dispersion relations in the fluid phase of Yukawa systems are obtained from molecular dynamics (MD) simulations for a wide range of the parameters. The Yukawa system is a collection of particles interacting through Yukawa (i.e., screened Coulomb) potentials, which can serve as a simple model for dusty plasmas. Our simulations have clearly shown that the transverse wave dispersion has a cutoff at a long wavelength even in the case of weak screening. The MD simulation data are compared with earlier theoretical predictions of the Yukawa dispersion relations and the validity of these theories is clarified. © 2000 The American Physical Society
Molecular dynamics simulation of silicon and silicon dioxide etching by energetic halogen beams
No full textH. Ohta and S. Hamaguchi, Journal of Vacuum Science & Technology A 19, 2373 (2001) https://doi.org/10.1116/1.1385906Molecular dynamics (MD) simulations for silicon and silicon dioxide etching by energetic halogens (F, or Cl), using new sets of interatomic potentials were performed. Sputtering yields for silicon and oxide targets was obtained from the MD simulations. Simultions also showed different target surface structures for fluorine and chlorine beam etching processes, which were accounted for by the difference in atomic size and binding energy between fluorine and chlorine
Classical interatomic potentials for Si-O-F and Si-O-Cl systems
No full textH. Ohta and S. Hamaguchi, J. Chem. Phys. 115, 6679 (2001) https://doi.org/10.1063/1.1400789For Si-O-F and Si-O-Cl systems, Stillinger-Weber (SW)-type potential sets were developed based on interatomic potential energy data obtained from ab initio quantum-mechanical calculations. The aim of the potential development was to perform molecular dynamics (MD) simulations for both silicon and silicon dioxide etching by Cl or F on the same footing. Details of the potential derivation and some sample MD simulation results were also presented
Molecular dynamics evaluation of self-diffusion in Yukawa systems
No full textH. Ohta and S. Hamaguchi, Physics of Plasmas 7, 4506 (2000) https://doi.org/10.1063/1.1316084Self-diffusion coefficients of Yukawa systems in the fluid phase are obtained from molecular dynamics simulations in a wide range of the thermodynamical parameters. The Yukawa system is a collection of particles interacting through Yukawa (i.e., screened Coulomb) potentials, which may serve as a model for charged dust particles in a plasma or colloidal particles in electrolytes. The self-diffusion coefficients are found to follow a simple scaling law with respect to the system temperature, which is consistent with the universal scaling (i.e., temperature scaling independent of the ratio of interparticle distance to screening length) observed by Robbins et al. [J. Chem. Phys. 88, 3286 (1988)] if the fluid system is near solidification. Also discussed is the velocity autocorrelation function, which is in part used to determine the self-diffusion coefficients through the Green-Kubo formula. © 2000 American Institute of Physics
Triple point of Yukawa systems
No full textS. Hamaguchi, R. T. Farouki, and D. H. E. Dubin,Phys. Rev. E 56, 4671, 1997The molecular dynamics simulations of Yukawa (i.e., screened-Coulomb) systems that were applied to the regime of weak screening in an earlier study [S. Hamaguchi, R. T. Farouki, and D. H. E. Dubin, J. Chem. Phys. 105, 7641 (1996)] are extended to the strong screening regime. Transition temperatures at the fluid-solid phase boundary and the solid-solid phase boundary are obtained as functions of the screening parameter [Formula Presented] (i.e., the ratio of the Wigner-Seitz radius [Formula Presented] to the Debye length [Formula Presented]). The resulting phase diagram also covers the triple point—the intersection of the fluid-solid and solid-solid phase boundaries—at [Formula Presented] and [Formula Presented] where Γ is the ratio of the Coulomb potential energy to the kinetic energy per particle (i.e., [Formula Presented] where [Formula Presented] is the charge of each Yukawa particle and [Formula Presented] is the system temperature). Yukawa systems serve as models for plasmas and colloidal suspensions of charged particulates. © 1997 The American Physical Society
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Self-limiting processes in thermal atomic layer etching of nickel by hexafluoroacetylacetone
No full textAbdulrahman H. Basher, Ikutaro Hamada, and Satoshi Hamaguchi. Jpn. J. Appl. Phys. 59 090905.In thermal atomic layer etching (ALE) of Ni, a thin oxidized Ni layer is removed by a hexafluoroacetylacetone (hfacH) etchant gas at an elevated surface temperature, and etching ceases when a metallic Ni surface appears (self-limiting step). However, atomistic details of the self-limiting step was not well understood. With periodic density-functional-theory calculations, it is found that hfacH molecules barrierlessly adsorb and tend to decompose on a metallic Ni surface, in contrast to the case of a NiO surface, where they can form volatile Ni(hfac)2. Our results clarify the origin of the self-limiting process in the thermal ALE
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