Formation and Its Mechanism of High-speed Micro-grooving on Metal Surface by Angled CW Laser Irradiation

In general, pulsed lasers with high peak power have been used for the micro-groove formation. However, the processing speed is limited by the pulse repetition rate. On the other hand, CW laser can be expected to perform the high-speed processing by continuous energy input. The mechanism of micro-groove formation by CW laser was investigated by high-speed observation and the thermal fluid analysis. In the perpendicular irradiation of CW laser, the molten metal flows symmetrically around the keyhole to the backward direction, and micro-grooves remain at both edges of molten region. In contrast, in the angled irradiation, the molten metal at the reflection-side scatters as spatters. The remained molten metal flows from the reflection-side to the incident-side through the bottom of keyhole, since the recoil pressure is generated from the reflection-side to the incident-side. In addition, high-speed scanning contributes to keeping the sufficient time and force to move the molten metal in the backward direction. Then, the micro-groove remains at the reflection-side, while the upheaval is formed at the incident-side by gathering the molten metal from the reflection-side and the front of keyhole. Asymmetrical behavior of molten metal flow in angled irradiation of CW laser can create micro-groove in the reflection-side

Wind- and Operation-Induced Vibration Measurements of the Main Reflector of the Nobeyama 45 m Radio Telescope

As deformations of the main reflector of a radio telescope directly affect the observations, the evaluation of the deformation is extremely important. Dynamic characteristics of the main reflector of the Nobeyama 45 m radio telescope, Japan, are measured under two conditions: The first is when the pointing observation is in operation, and the second is when the reflector is stationary and is subjected to wind loads when the observation is out of operation. Dynamic characteristics of the main reflector are measured using piezoelectric accelerometers. When the telescope is in operation, a vibration mode with one nodal line horizontally or vertically on the reflector is induced, depending on whether the reflector is moving in the azimuthal or elevational planes, whereas under windy conditions, vibration modes that have two to four nodal lines are simultaneously induced. The predominant mode is dependent on the direction of wind loads.Comment: Accepted for publication in Journal of Vibration Engineering & Technologie

Characterization of sensitivity and responses of a 2-element prototype wavefront sensor for millimeter-wave adaptive optics attached to the Nobeyama 45 m telescope

We report the results of the performance characterization of a prototype wavefront sensor for millimetric adaptive optics (MAO) installed on the Nobeyama 45 m radio telescope. MAO is a key component to realize a future large-aperture submillimeter telescope, such as Large Submillimeter Telescope (LST) or Atacama Large Aperture Submillimeter Telescope (AtLAST). The difficulty of MAO is, however, real-time sensing of wavefront deformation with ~10 um accuracy across the aperture. Our wavefront sensor operating at 20 GHz measures the radio path length between a certain position of the primary mirror surface to the focal point where a 20 GHz coherent receiver is placed. With the 2-element prototype, we sampled two positions on the primary mirror surface (at radii of 5 m and 16 m) at a sampling rate of 10 Hz. Then an excess path length (EPL) between the two positions was obtained by differentiating the two optical paths. A power spectral density of the EPL shows three components: a low-frequency drift (1/f^n), oscillations, and a white noise. A comparison of EPL measurements under a variety of wind conditions suggests that the former two are likely induced by the wind load on the telescope structure. The power of the white noise corresponds to a 1sigma statistical error of 8 um in EPL measurements. The 8 um r.m.s. is significant with respect to the mirror surface accuracy required by the LST and AtLAST (~20-40 um r.m.s.), which demonstrates that our technique is also useful for the future large-aperture submillimeter telescopes.Comment: 10 pages, 9 figures. Published in SPIE Pro

The Relationship between Generic Competency and Music-Specific Attributes and Abilities: Experimental Schools of the Ministry of Education, Culture, Sports, Science and Technology

The current study examined experimental schools of the Ministry of Education, Culture, Sports, Science and Technology, which were set up to research generic competency. The current study sought to clarify the relationships between generic competency and music-specific ability in theses experimental schools. All of the schools and kindergartens examined in the current study aimed to foster generic competency in new domains and new subjects, and showed a clear connection between other existing subjects including music and these new domains and/or subjects. We founded the attributes, abilities, aims and content in music were connected to generic competency. Music was not just a tool to foster generic competency. As mentioned above, in all of the schools we examined, competency in specific subjects was not the focus. The current results raised several important suggestions for improving curriculum management

Related polymorphic F-box protein genes between haplotypes clustering in the BAC contig sequences around the S-RNase of Japanese pear

Most fruit trees in the Rosaceae exhibit self-incompatibility, which is controlled by the pistil S gene, encoding a ribonuclease (S-RNase), and the pollen S gene at the S-locus. The pollen S in Prunus is an F-box protein gene (SLF/SFB) located near the S-RNase, but it has not been identified in Pyrus and Malus. In the Japanese pear, various F-box protein genes (PpSFBB-α–γ) linked to the S-RNase are proposed as the pollen S candidate. Two bacterial artificial chromosome (BAC) contigs around the S-RNase genes of Japanese pear were constructed, and 649 kb around S4-RNase and 378 kb around S2-RNase were sequenced. Six and 10 pollen-specific F-box protein genes (designated as PpSFBB4-u1–u4, 4-d1–d2 and PpSFBB2-u1–u5, 2-d1–d5, respectively) were found, but PpSFBB4-α–γ and PpSFBB2-γ were absent. The PpSFBB4 genes showed 66.2–93.1% amino acid identity with the PpSFBB2 genes, which indicated clustering of related polymorphic F-box protein genes between haplotypes near the S-RNase of the Japanese pear. Phylogenetic analysis classified 36 F-box protein genes of Pyrus and Malus into two major groups (I and II), and also generated gene pairs of PpSFBB genes and PpSFBB/Malus F-box protein genes. Group I consisted of gene pairs with 76.3–94.9% identity, while group II consisted of gene pairs with higher identities (>92%) than group I. This grouping suggests that less polymorphic PpSFBB genes in group II are non-S pollen genes and that the pollen S candidates are included in the group I PpSFBB genes