C-RECS （Creative Repository of Electro-Communications)
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Elucidation of the boiling characteristics in the subcooled flow boiling at low pressures
Get PDF電気通信大学博士（工学）2024doctoral thesi
単一磁束量子パルス周波数変調型D/A変換器のGHz信号生成回路への応用
Get PDF単一磁束量子(Single Flux Quantum: SFQ)回路の応用の一つとして交流電圧標準がある．これを実現するために，交流ジョセフソン効果で定義された高精度な電圧を生成するパルス周波数変調型D/A 変換器(Digital/Analog Converter: DAC) の開発が行われている．“sum of Selected Bit Sequences (-SBS)”型と呼ばれるDAC はその一つであり，生成電圧の精度の高さを保ちながら，取り扱うSFQ パルス列周波数が120 GHz 程度に達する高速動作性を有する．本研究では，-SBS DAC の高速動作性を活かしてマイクロ波を生成する回路を設計し，数値計算により動作検証並びに動作可能範囲の探索を行った．結果として，目標であった周波数1 GHz の両極性疑似正弦波に相当するSFQ パルス列の周波数変調を達成した．また，回路の生成できる正弦波の周波数は10 MHz–1 GHz であった．journal articl
B-Doped Fullerene as a Potential Metal-Free Catalyst Material for CO Reduction Reaction
Get PDFReducing carbon monoxide (CO) plays an essential role in the goal of C1 chemistry. This study aims to design and develop B-doped fullerenes as the electrocatalyst for the CO reduction reaction using first-principles calculations based on density functional theory. The computational hydrogen electrode model has been employed to evaluate the catalytic properties of B-doped fullerene. It has been confirmed that the CO molecule adsorbs stably on C59B with an adsorption energy of −0.35 eV. When an external voltage of 0.39 V, the overvoltage, is applied, all reactions proceed downhill, selectively producing methane in an acidic environment. This value is sufficiently lower than previously reported values on metal surfaces. The reaction process to determine the overvoltage is the initial hydrogenation process, *CO → *CHO. On the other hand, the CO molecule does not adsorb on a flat B-doped graphene nanocluster, implying that the curvature of the carbon network plays an important role in CO adsorption. Thus, we have investigated the dependence of the radius of the curvature on the adsorption energy and the overvoltage using a different size of fullerene, C69B. The reaction site with a radius of curvature of 4.86 Å for C69B has a minimum overvoltage of 0.26 V. However, the adsorption energy of CO molecules is −0.12 eV, higher than that of C59B. This suggests the existence of an optimal radius of curvature for various applications. The curvature of the fullerene surface plays an important role as a catalyst for the CO reduction. This research will pave the way for developing catalytic properties of surfaces with curvature.journal articl
Effects of Rhythm and Accent Patterns on Tempo-Keeping Property of Finger Tapping
Get PDFTempo of music performance is often accelerated irrespective of players’ intention. Though the characteristics of the tempo deviation phenomenon have been investigated using a finger-tapping task, most such studies dealt with tapping with a fixed interval and intensity; few studies considered the effects of rhythm and accent, both important factors of music performance. Here, we asked how different rhythm and accent patterns affected the tempo-keeping property using a synchronization-continuation task paradigm: Participants were asked to keep tapping with reproducing the given rhythm/accent patterns designated by the target tones. Tapping tempo was significantly deviated depending on rhythm/accent patterns, but their magnitudes were only several percent in 150 s, much smaller than those in real music performance. We also ran experiments in the conditions that participants need not reproduce the accent patterns but only response tones were accented. These auditory modulations affected the tempo deviation, implying that perceptual processes induced by the auditory feedback also influence the tempo maintenance. Inter-tap intervals (ITIs) were modulated by the accent pattern, but no clear relationship was observed between ITI fluctuations and long-term tempo deviation, suggesting that different mechanisms are involved. In sum, the present finding shows that non-uniform motor actions required for music articulation can disturb the long-term tempo maintenance but their effect is rather small. We also reported the tempo deviation when the response tone was modulated by loudness (crescendo vs. diminuendo) or pitch (ascending vs. descending).journal articl
Panel discussion “Medium- and long-term strategies for training the next generation”
Get PDFTraining young people who will lead the future is important in any field including academic activities. In this panel discussion, we will introduce the efforts that six science and engineering societies (The Japan Society for Aeronautical and Space Sciences, The Institute of Electronics, Information and Communication Engineers, Information Processing Society of Japan, The Physical Society of Japan, The Japan Society of Mechanical Engineers, and The Astronomical Society of Japan) are conducting for juniors. We will discuss what the academic societies should do for the next generation.conference pape
