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MHD SIMULATIONS OF A MOVING SUB CLUMP WITH HEAT CONDUCTION
ASAI NAOKI,FUKUDA NAOYA,MATSUMOTO RYOJI The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.5
High resolution observations of cluster of galaxies by Chandra have revealed the existence of an X-ray emitting comet-like galaxy C153 in the core of cluster of galaxies A2125. The galaxy C153 moving fast in the cluster core has a distinct X-ray tail on one side, obviously due to ram pressure stripping, since the galaxy C153 crossed the central region of A2125. The X-ray emitting plasma in the tail is substantially cooler than the ambient plasma. We present results of two-dimensional magnetohydrodynamic simulations of the time evolution of a sub clump like C153 moving in magnetized intergalactic matter. Anisotropic heat conduction is included. We found that the magnetic fields are essential for the existence of the cool X-ray tail, because in non-magnetized plasma the cooler sub clump tail is heated up by isotropic heat conduction from the hot ambient plasma and does not form such a comet-like tail.
Kawakatsu Takashi,Fukuda Naoya 한국원예학회 2023 Horticulture, Environment, and Biotechnology Vol.64 No.4
Ginseng is a deciduous, perennial herb with diverse pharmacological properties. The usual method for raising seedlings has many problems due to instabilities by the natural environment and diseases. A plant factory system with artifi cial light (PFAL) can potentially overcome the problems. However, there is a limited understanding of optimal cultivation conditions for raising ginseng seedlings in PFAL. We evaluated the eff ects of air temperature, photosynthetic photon fl ux density (PPFD), electric conductivity (EC) of the nutrient solution, and planting density on the growth and physiological traits of ginseng grown in a closed environment. Root weight at 20 °C was signifi cantly higher than that at 25 °C. Root weight increased under PPFD of 130 μmol m −2 s −1 compared to 30 μmol m −2 s −1 ; however, there was no diff erence in root weight between PPFD of 230 μmol m −2 s −1 and 130 μmol m −2 s −1 . The PPFD of 370 μmol m −2 s −1 decreased Fv/Fm and root growth. Dense planting increased the specifi c leaf area and SPAD under PPFD of 220 μmol m −2 s −1 , suggesting that competition for light occurred. However, the number of good seedlings (> 0.94 g) per pot increased in proportion to planting density with a higher EC (1.5 dS m −1 ). In addition, the higher planting density increased the number of available seedlings (0.68 to 0.94 g) regardless of light intensity or EC. Therefore, a plant density higher than the density usually employed for cultivation can be applied to achieve high productivity for the growth of seedlings in PFAL.
The Development of a Power System of the Combination of Diesel Generator and UPS
Dawei Qiu,Satoshi Uda,Hironori Kashihara,Yuki Fukuda,Naoya Okazaki,Shoji Nishimura,Yoshinori Kawasaki 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
This paper shows the development of a power supply system to solve the anomalous voltage sag, power failure and peak cut demand. This power supply system includes an UPS (Uninterruptible Power Supply), a standby generator and a Hybrid Switch, which is the integration of mechanical switches and IGBTs with good performance of low conducting loss and fast opening time. The results of a real-time simulation demonstrate its voltage compensation can perform within 2 ms response time when power failure occurs and transfer without voltage down between micro grid operation and gird-connected operation. Also, they are successfully validated by using a prototype system.