Sound Generation by a Turbulent Flow in Musical Instruments - Multiphysics Simulation Approach -

Total computational costs of scientific simulations are analyzed between direct numerical simulations (DNS) and multiphysics simulations (MPS) for sound generation in musical instruments. In order to produce acoustic sound by a turbulent flow in a simple recorder-like instrument, compressible fluid dynamic calculations with a low Mach number are required around the edges and the resonator of the instrument in DNS, while incompressible fluid dynamic calculations coupled with dynamics of sound propagation based on the Lighthill's acoustic analogy are used in MPS. These strategies are evaluated not only from the viewpoint of computational performances but also from the theoretical points of view as tools for scientific simulations of complicated systems.Comment: 6 pages, 10 figure files, to appear in the proceedings of HPCAsia0

アメリカにおけるメディアリテラシー（３）―2000年から2000年代中葉まで―

本稿では２０００年以降のメディアリテラシー教育の発展を考察する。この時 期におけるメディア教育の特徴は，①米政府のこの分野に対する一層の関心の高 まりと，②メディアリテラシーに関する研究組織の設立や教育機関との連携によ る組織的な成長の土台作りの完成の二点に尽きる。この時期のさまざまな動きを 概観しながら，さらにそれと今日のメディア状況との連関にもふれながら論考し たい。 2000年以降のメディア教育の歩みの結果が，大きなメディア転換点とも評価され るべき2016年へとつながるとも言える。2000年以降の概要考察にあたり，大統領 選挙を挟む2016年のアメリカのメディア状況にもふれる

アメリカにおけるメデイアリテラシー(1) …1990年代前半まで

アメリカにおける「メデｲア教育｣がはじまったのは、「メデｲアリテラシー」という概念も用語もまだなかった1960年代とされる。そのような時代にあってもアメリカ各地には、マスメデｲアの持つ可能性とそのもたらすであろう様々な課題をいち早く予感し、次代を担う子供たちにどのようにメデｲアとむかい合わせるのかという問題意識を持った教員や研究者が多く存在した。60年代以降このような人材が次第にこの問題意識を共有し、組織化され今に至る「メデｲアリテラシー」教育へと結実してきた。本編ではアメリカにおける1990年代前半までのメデｲアリテラシーの歴史を概観する

Gauge Theories in Noncommutative Homogeneous K\"ahler Manifolds

We construct a gauge theory on a noncommutative homogeneous K\"ahler manifold, where we employ the deformation quantization with separation of variables for K\"ahler manifolds formulated by Karabegov. A key point in this construction is to obtaining vector fields which act as inner derivations for the deformation quantization. We show that these vector fields are the only Killing vector fields. We give an explicit construction of this gauge theory on noncommutative ${\mathbb C}P^N$ and noncommutative ${\mathbb C}H^N$.Comment: 27 pages, typos correcte

Theoretical Estimation of the Acoustic Energy Generation and Absorption Caused by Jet Oscillation

We investigate the energy transfer between the fluid field and acoustic field caused by a jet driven by an acoustic particle velocity field across it, which is the key to understanding the aerodynamic sound generation of flue instruments, such as the recorder, flute, and organ pipe. Howe’s energy corollary allows us to estimate the energy transfer between these two fields. For simplicity, we consider the situation such that a free jet is driven by a uniform acoustic particle velocity field across it. We improve the semi-empirical model of the oscillating jet, i.e., exponentially growing jet model, which has been studied in the field of musical acoustics, and introduce a polynomially growing jet model so as to apply Howe’s formula to it. It is found that the relative phase between the acoustic oscillation and jet oscillation, which changes with the distance from the flue exit, determines the quantity of the energy transfer between the two fields. The acoustic energy is mainly generated in the downstream area, but it is consumed in the upstream area near the flue exit in driving the jet. This theoretical examination well explains the numerical calculation of Howe’s formula for the two-dimensional flue instrument model in our previous work [Fluid Dyn. Res. 46, 061411 (2014) ] as well as the experimental result of Yoshikawa et al. [ J. Sound Vib. 331, 2558 (2012) ]

Surface smoothing of additively manufactured Ti-6Al-4V alloy by combination of grit blasting and large-area electron beam irradiation

Additively manufactured (AMed) titanium products are typically produced by electron beam melting (EBM), since oxidation of titanium alloy surface can be suppressed in vacuum environment. The surface roughness of AMed titanium products becomes more than 200 µm Rz, and the very rough surface would lead to reduction in fatigue strength. Therefore, a post surface finishing process is required. Abrasive blasting is one of the common surface smoothing processes of AMed metal products. Large surface roughness can be decreased, and compressive residual stress can be introduced to the surface. However, there is a limitation to reduction of surface roughness to several µm Rz. On the other hand, it was recently found that AMed metal surface produced by powder bed fusion with laser beam could be smoothed by large-area electron beam (LEB) irradiation. However, it is difficult to smooth surface with large initial surface roughness, and a tensile residual stress may be generated on the surface. In this study, surface smoothing and change in residual stress of AMed titanium alloy (Ti-6Al-4 V) were proposed by combination of grit blasting and LEB irradiation. Surface roughness of AMed Ti-6Al-4 V alloy significantly decreases from 265 to about 2.0 µm Rz by combination of grit blasting and LEB irradiation. Reduction rate of surface roughness by LEB irradiation linearly increases with decreasing mean width of blasted surface. Influence of the mean width on smoothing effect by LEB irradiation can be explained by thermo-fluid analysis. Moreover, tensile residual stress caused by LEB irradiation can be reduced when LEB is irradiated to blasted surface

Open-architecture Implementation of Fragment Molecular Orbital Method for Peta-scale Computing

We present our perspective and goals on highperformance computing for nanoscience in accordance with the global trend toward "peta-scale computing." After reviewing our results obtained through the grid-enabled version of the fragment molecular orbital method (FMO) on the grid testbed by the Japanese Grid Project, National Research Grid Initiative (NAREGI), we show that FMO is one of the best candidates for peta-scale applications by predicting its effective performance in peta-scale computers. Finally, we introduce our new project constructing a peta-scale application in an open-architecture implementation of FMO in order to realize both goals of highperformance in peta-scale computers and extendibility to multiphysics simulations.Comment: 6 pages, 9 figures, proceedings of the 2nd IEEE/ACM international workshop on high performance computing for nano-science and technology (HPCNano06