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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.07.019 Byline: Jun Nozawa (a), Katsuo Tsukamoto (a), Hidekazu Kobatake (a)(b), Junya Yamada (a), Hisao Satoh (a)(c), Ken Nagashima (a)(d), Hitoshi Miura (a), Yuki Kimura (a) Keywords: Meteorites; Solar nebula; Interplanetary dust Abstract: By means of nanoscale surface observation, we have proposed a new approach for investigating fine crystals of cosmic materials to reveal their origin and growth conditions. Several different morphologies of polyhedral fine olivines with faceted faces have been found in Allende carbonaceous chondrite (4.5byr in geochronological age). In the present work, molecular level topography of the faceted matrix olivine by Atomic Force Microscopy (AFM) has successfully been performed. The matrix olivine found to have preserved growth step pattern on its surface even though quite long time has passed since they formed in the early Solar System. The surface pattern suggests that the faceted matrix olivine could have been condensed from the gas phase, and possibly that these olivine crystals had continued to grow under a rapid cooling condition (0.1-1Ks.sup.-1). The estimated cooling rate agrees well with predictions based on hypothetical rapid heating and cooling events such as shock wave heating. Author Affiliation: (a) Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Japan (b) Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan (c) SERNUC Corporation, Mitsubishi Materials Corporation, 1-297, Kitabukuro, Omiya-ku, Saitama 330-0835, Japan (d) Division of Electrical, Electronic and Information Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamada-Oka, Suita 565-0871, Japan Article History: Received 11 January 2008; Revised 16 June 2009; Accepted 1 July 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2008.06.006 Byline: Hidekazu Kobatake (a)(b), Katsuo Tsukamoto (b), Jun Nozawa (b), Ken Nagashima (b), Hisao Satoh (b), Peter Dold (b) Keywords: Interplanetary dust; Meteorites; Origin; Solar System Abstract: Growth conditions and the resultant morphology of cosmic forsterite and enstatite particles condensed from the vapor were investigated experimentally as a function of growth temperature and supersaturation using flash-heating by CO.sub.2 laser irradiation. Forsterite particles grew dominantly, followed by a few pyroxenes. No silica minerals were observed. The forsterite morphology changed systematically depending on the temperature (T) and the vapor supersaturation (I). As the temperature decreased and the vapor supersaturation increased, the forsterite morphology changed from a bulky type (T=1000-1450a[degrees]C, I Author Affiliation: (a) Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan (b) Faculty of Science, Institute of Mineralogy, Petrology and Economic Geology, Tohoku University, Aoba-ku, Sendai 980-8578, Japan Article History: Received 27 October 2006; Revised 5 June 2008

Accurate prediction of oil dispersion has been challenging due to its highly deformed/dispersed interface as well as small-scale oil-water mixing. In this paper, a refined Incompressible SPH (Smoothed Particle Hydrodynamics)-based method is proposed for simulations of oil spill problems. In the proposed method, the presence of oil is taken into consideration with concentration function and physical properties of computational points (particles), i.e. density and viscosity, are varied based on the concentration of oil. The proposed method incorporates a LES-based turbulence model, namely SPS (Sub-Particle-Scale) turbulence model, in order to capture small-scale turbulence effects. Diffusion equation is further implemented so as to reproduce the sub-particle-scale oil-water mixing effects. Interfacial surface tension is considered through potential-based modeling with consideration of the highly deformed/dispersed interface. A set of previously proposed refined schemes are also applied for accurate/robust simulations. The stability and accuracy of proposed ISPH-based method are investigated by conducting benchmark tests. [ABSTRACT FROM AUTHOR]

Chondrules are submillimeter-sized and spherical-shaped crystalline grains consisting mainly of silicate material observed in chondritic meteorites. We numerically simulated pattern formation of a forsterite (Mg2SiO4)-chondrule in the melt droplet using a phase-field method. Because of the large surface-to-volume ratio, the surface cooling term was introduced in the framework of this method. We reproduced an unique crystal growth pattern inside the droplet composed of two distinguishable parts; the rim that covers whole droplet surface, and dendrite inside the droplet. It was found that the rim was formed when there is a large temperature difference of ∼100 K between the center and surface of the droplet due to the large cooling flux at the surface. In order to obtain the temperature difference, we derived temperature distribution of the droplet analytically, and concluded that the rim was formed only when the droplet cools rapidly at a rate of Rcool∼103 K s-1. However, when the surface cooling was so large as the temperature at the droplet center still remains above the melting point, no dendrite was obtained, though the rim was formed. The double structure captures the distinctive features of barred-olivine textures observed in natural chondrules. [ABSTRACT FROM AUTHOR]

The world's largest-class flywheel energy storage system (FESS), with a 300 kW power, was established at Mt. Komekura in Yamanashi prefecture in 2015. The FESS, connected to a 1-MW megasolar plant, effectively stabilized the electrical output fluctuation of the photovoltaic (PV) power plant caused by the change in sunshine. The FESS uses a superconducting magnetic bearing (SMB) to levitate a heavy weight flywheel rotor without mechanical contact. The SMB consists of high-temperature superconducting coils (HTS coils) made of rare-Earth-Ba2Cu3Oy , superconducting tapes, and high-temperature superconducting plates (HTS plates) made of YBa2Cu3 Oy. The HTS plates in the rotor axis received the levitation forces in the magnetic field generated by the HTS coils in the stator. At first, the SMB was tested alone to check its cooling properties and to measure the levitation force. In the factory test, the SMB was confirmed to levitate the 4000-kg load, and its performance and basic reliability were verified. In the verification test, at Mt. Komekura, the FESS rotor reached a maximum of 2950 r/min, and the FESS was charged and discharged at 300 kW in the PV plant. [ABSTRACT FROM PUBLISHER]

High temperature bulk superconductors have significant potential for various engineering applications such as a flywheel energy storage system. This system is expected to decrease the energy loss by using bulk superconductors for the bearing. Recently, the authors have developed a new superconducting magnet to realize the large levitation force. The magnet has two coils on the same axis and each coil's current flows to the opposite direction. In this system, the axial component of magnetic field is canceled each other but the radial component of magnetic field is expected to be enhanced. In this paper, the authors measured the levitation force and its time relaxation at different bulk positions in both cases of one and two bulks by using this new magnet. From the results, it was made clear that the levitation force of two bulks was twice as large as that of one bulk and its time relaxation was decreased. In addition, Hall sensors were attached on the sample surface to measure the surface magnetic field distribution. The behavior of the magnetic field was discussed. [ABSTRACT FROM AUTHOR]

Discusses the control of the levitation of bulk Y-Ba-Cu-O superconductors using a Bi-Sr-Ca-Cu-O superconducting electromagnet. Levitation analysis based on the total energy balance; Condition under which stable levitation of superconductors with large dimensions can be achieved.

For EDS-type magnetically levitated trains, magnetic shielding of stray fields produced by superconducting magnets is an important task. We seek the “optimal” thickness distribution (configuration) of magnetic material, which is the lightest and keeps the magnetic field at tolerable levels in the vehicle. In many cases, trial-and-error methods have been adopted for this purpose. In this paper, we propose a new method for preliminary design of the magnetic shielding. In this method, we simplify the magnetic shielding problem, assuming infinite permeability of the magnetic material, and calculate the magnetic flux going into or out of the shield surface. In this case, we can design an optimal magnetic shield (distribution and configuration of the magnetic material) and know the minimum weight of the magnetic shielding. We finally present an example of the magnetic shielding designed by this method and investigate its characteristics in a magnetically levitated train. © 1998 Scripta Technica, Electr Eng Jpn, 124(1): 42–54, 1998 [ABSTRACT FROM AUTHOR]

The surfaces of ice crystals near the melting point are covered with thin liquid water layers, called quasi-liquid layers (QLLs), which play crucial roles in various chemical reactions in nature. So far, there have been many spectroscopic studies of such chemical reactions on ice surfaces, however, revealing the effects of atmospheric gases on ice surfaces remains an experimental challenge. In this study, we chose HNO3 as a model atmospheric gas, and directly observed the ice basal faces by advanced optical microscopy under partial pressure of HNO3 (~10−4 Pa), relevant to those found in the atmosphere. We found that droplets (HNO3-QLLs) appeared on ice surfaces at temperatures ranging from −0.9 to −0.2 °C with an increase in temperature, and that they disappeared at temperatures ranging from −0.6 to −1.3 °C with decreasing temperature. We also found that the size of the HNO3-QLLs decreased immediately after we started reducing the temperature. From the changes in size and the liquid–solid phase diagram of the HNO3-H2O binary system, we concluded that the HNO3-QLLs did not consist of pure water, but rather aqueous HNO3 solutions, and that the temperature and HNO3 concentration of the HNO3-QLLs also coincided with those along a liquidus line. [ABSTRACT FROM AUTHOR]

The hydrogenation of CO over a RhVO4/SiO2 catalyst has been investigated after H2 reduction at 773 K. A strong metal–oxide interaction (SMOI) induced by the decomposition of RhVO4 in H2 enhanced not only the selectivity to C2 oxygenates but also the CO conversion drastically, compared with an unpromoted Rh/SiO2 catalyst. The selectivity of the RhVO4/SiO2 catalyst was similar to those of conventional V2O5 promoted Rh/SiO2 catalysts (V2O5–Rh/SiO2), but the CO dissociation activity (and TOF) was much higher than for V2O5–Rh/SiO2, and hence the yield of C2 oxygenates was increased. [ABSTRACT FROM AUTHOR]

The free growth of ice crystals in supercooled bulk water containing an impurity of glycoprotein, a bio-macromolecule that functions as 'antifreeze' in living organisms in a subzero environment, was observed under microgravity conditions on the International Space Station. We observed the acceleration and oscillation of the normal growth rates as a result of the interfacial adsorption of these protein molecules, which is a newly discovered impurity effect for crystal growth. As the convection caused by gravity may mitigate or modify this effect, secure observations of this effect were first made possible by continuous measurements of normal growth rates under long-term microgravity condition realized only in the spacecraft. Our findings will lead to a better understanding of a novel kinetic process for growth oscillation in relation to growth promotion due to the adsorption of protein molecules and will shed light on the role that crystal growth kinetics has in the onset of the mysterious antifreeze effect in living organisms, namely, how this protein may prevent fish freezing. [ABSTRACT FROM AUTHOR]