Analytical Model for Phase Synchronization of a Pair of Vertical-Axis Wind Turbines

The phase-synchronized rotation of a pair of closely spaced vertical-axis wind turbines has been found in wind tunnel experiments and computational fluid dynamics (CFD) simulations. During phase synchronization, the two wind turbine rotors rotate inversely at the same mean angular velocity. The blades of the two rotors pass through the gap between the turbines almost simultaneously, while the angular velocities oscillate with a small amplitude. A pressure drop in the gap region, explained by Bernoulli’s law, has been proposed to generate the interaction torque required for phase synchronization. In this study, an analytical model of the interaction torques was developed. In our simulations using the model, (i) phase synchronization occurred, (ii) the angular velocities of the rotors oscillated during the phase synchronization, and (iii) the oscillation period became shorter and the amplitude became larger as the interaction became stronger. These observations agree qualitatively with the experiments and CFD simulations. Phase synchronization was found to occur even for a pair of rotors with slightly different torque characteristics. Our simulation also shows that the induced flow velocities influence the dependence of the angular velocities during phase synchronization on the rotation directions of the rotors and the distance between the rotors

アンジオテンシンIIタイプ1レセプター遮断による移植後冠動脈硬化症モデルマウスの冠動脈病変抑制効果に関する研究

京都大学0048新制・課程博士博士(医学)甲第6766号医博第1866号新制||医||661(附属図書館)15838UT51-97-H150京都大学大学院医学研究科内科系専攻(主査)教授 伴 敏彦, 教授 眞崎 知生, 教授 篠山 重威学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDA

Numerical Analysis of the Dynamic Interaction between Two Closely Spaced Vertical-Axis Wind Turbines

To investigate the optimum layouts of small vertical-axis wind turbines, a two-dimensional analysis of dynamic fluid body interaction is performed via computational fluid dynamics for a rotor pair in various configurations. The rotational speed of each turbine rotor (diameter: D = 50 mm) varies based on the equation of motion. First, the dependence of rotor performance on the gap distance (gap) between two rotors is investigated. For parallel layouts, counter-down (CD) layouts with blades moving downwind in the gap region yield a higher mean power than counter-up (CU) layouts with blades moving upwind in the gap region. CD layouts with gap/D = 0.5–1.0 yield a maximum average power that is 23% higher than that of an isolated single rotor. Assuming isotropic bidirectional wind speed, co-rotating (CO) layouts with the same rotational direction are superior to the combination of CD and CU layouts regardless of the gap distance. For tandem layouts, the inverse-rotation (IR) configuration shows an earlier wake recovery than the CO configuration. For 16-wind-direction layouts, both the IR and CO configurations indicate similar power distribution at gap/D = 2.0. For the first time, this study demonstrates the phase synchronization of two rotors via numerical simulatio

Molecular Clouds as a Probe of Cosmic-Ray Acceleration in a Supernova Remnant

We study cosmic-ray acceleration in a supernova remnant (SNR) and the escape from it. We model nonthermal particle and photon spectra for the hidden SNR in the open cluster Westerlund 2, and the old-age mixed-morphology SNR W 28. We assume that the SNR shock propagates in a low-density cavity, which is created and heated through the activities of the progenitor stars and/or previous supernova explosions. We indicate that the diffusion coefficient for cosmic-rays around the SNRs is less than ~1% of that away from them. We compare our predictions with the gamma-ray spectra of molecular clouds illuminated by the cosmic-rays (Fermi and H.E.S.S.). We found that the spectral indices of the particles are ~2.3. This may be because the particles were accelerated at the end of the Sedov phase, and because energy dependent escape and propagation of particles did not much affect the spectrum.Comment: Accepted for publication in ApJ Letter

Responses to depressive symptom items exhibit a common mathematical pattern across the European populations

The theoretical distribution of responses to depressive symptom items in a general population remains unknown. Recent studies have shown that responses to depressive symptom items follow the same pattern in the US and Japanese populations, but the degree to which these findings can be generalized to other countries is unknown. The purpose of this study was to conduct a pattern analysis on the EU population’s responses to depressive symptom items using data from the Eurobarometer. The Eurobarometer questionnaires include six depressive symptom items from the 12-item General Health Questionnaire. The pattern analysis revealed that, across the entire EU population, the ratios between “score = 2” and “score = 1” and between “score = 3” to “score = 2” were similar among the six items and resulted in a common pattern. This common pattern was characterized by an intersection at a single point between “score = 0” and “score = 1” and a parallel pattern between “score = 1” and “score = 3” on a logarithmic scale. Country-by-country analyses revealed that the item responses followed a common characteristic pattern across all 15 countries. Our results suggest that responses to depressive symptom items in a general population follow the same characteristic pattern regardless of the specific country

Clinical efficacy and cytokine network-modulating effects of tacrolimus in myasthenia gravis

取得学位 : 博士（医学）, 学位授与番号 : 医博甲第1924号 , 学位授与年月日 : 平成20年3月22日, 学位授与大学 : 金沢大学, 主査教授 : 和田 隆志, 副査教授 : 向田 直史 , 中尾 眞

Photosynthetic rates of four tree species in the upper canopy of a tropical rain forest at the Pasoh Forest Reserve in Peninsular Malaysia

Measurements of photosynthesis (A) and stomatal conductance (gs) were conducted using the leaves of four tropical tree species (Dipterocarpus sublamellatus, Neobalanocarpus heimii, Ptychopyxis caput-medusae, and Xanthophyllum amoneum) in the canopy of the lowland forest at the Pasoh Forest Reserve in peninsular Malaysia. A canopy walkway was used to reach the canopy of 30- to 40-m-tall trees and diurnal changes in A and gs were determined. The diurnal patterns for A differed between days and between species, though A of the four species were similar but quite low. In general, A increased with increasing photosynthetically active radiation (PAR) before noon, then declined. As well, a linear relationship was detected between gs and A, but no statistically significant correlation could be confirmed between these two factors for D. sublamellatus and P. caput-medusae in November and July. The value of gs decreased with increasing vapor pressure deficit for D. sublamellatus, but the other species did not show this response