Spin rates of fast-rotating asteroids and fragments in impact disruption     

Toshihiko Kadono  Masahiko Arakawa  Takashi Ito  Keiji Ohtsuki 《Icarus》2009,200(2):694-697

We present a new experimental result of fragment spin-rate in impact disruption, using a thin glass plate. A cylindrical projectile impacts on a side (edge) of the plate. Dispersed fragments are observed using a high-speed camera and the spin rates of fragments are measured. We find that the measured fragment spin-rate decreases with increasing size. Assuming that the rotational energy of fragments is supplied from the residual stress, the spin rate ω decreases with increasing fragment size r as ω∼r−1, which explains the above experimental results. This size-dependence is similar to that of the observed spin rates of small fast-rotating asteroids. Our results suggest that spin rates of fragments of small asteroids immediately after disruption may have a similar size-dependence, and can provide constraints on the subsequent spin-state evolution of small asteroids due to thermal torques.  相似文献   

Editorial Appreciation     

John Leibacher  Takashi Sakurai  Lidia van Driel-Gesztelyi 《Solar physics》2009,255(1):1-2

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Solar Physics Publication Ethics Policies     

John Leibacher  Takashi Sakurai  Lidia van Driel-Gesztelyi 《Solar physics》2009,260(1):1-3

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The impact of radio feedback from active galactic nuclei in cosmological simulations: formation of disc galaxies     

Takashi Okamoto  Rodrigo S. Nemmen  Richard G. Bower 《Monthly notices of the Royal Astronomical Society》2008,385(1):161-180

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Preface: A Topical Issue on the <Emphasis Type="Italic">Hinode</Emphasis> Mission     

Takashi Sakurai 《Solar physics》2008,249(2):165-165

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Development of partial factor design method on bending strength of piles for Japanese Specifications for Highway Bridges     

Toshiaki Nanazawa  Tetsuya Kouno  Gaku Sakashita  Takashi Nakaura 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2019,13(3):176-184

ABSTRACT

This paper describes the development of a partial factor design method on the bending strength of piles for the Japanese Specifications for Highway Bridges. First, uncertainties in mobilised bending moments and yield bending moments were evaluated by Monte Carlo simulations. Second, the reliability of piles designed by the previous specifications were evaluated on the basis of reliability analysis considering uncertainties in the mobilised bending moments, yield bending moments, and other factors. Finally, a partial factor design method utilising a survey subsurface investigation method and ground type was developed to reach target reliability levels determined by the Standards.  相似文献   

Duluth Complex apatites: Age reference material for LA–ICP–MS‐based fission‐track dating     

Hideki Iwano  Tohru Danhara  Takashi Yuguchi  Takafumi Hirata  Masatsugu Ogasawara 《地学学报》2019,31(3):247-256

Anorthositic series apatites of the Duluth Complex, Minnesota, USA, have high spontaneous fission‐track densities of up to ~10⁷ cm^–2 and a homogeneous age of ~900 Ma, allowing high‐precision fission‐track dating based on LA–ICP–MS U analysis. Absolute fission‐track dating, track‐length measurement and chemical composition analysis were performed to evaluate a cooling history, which is essential for age reference materials. Preliminary inverse modelling for a sample with a shortened track‐length distribution yielded a monotonic cooling history from ~100°C at 925 Ma. The apatites incur an over‐etching problem when employing the commonly used etching protocol involving 5.5 M HNO₃.  相似文献   

Best practices for the use of meteorite names in publications     

Philipp R. Heck  Christopher Herd  Jeffrey N. Grossman  Dmitry Badjukov  Audrey Bouvier  Emma Bullock  Hasnaa Chennaoui‐Aoudjehane  Vinciane Debaille  Tasha L. Dunn  Denton S. Ebel  Ludovic Ferrire  Laurence Garvie  Jrme Gattacceca  Matthieu Gounelle  Richard Herd  Trevor Ireland  Emmanuel Jacquet  Robert J. Macke  Tim McCoy  Francis M. McCubbin  Takashi Mikouchi  Knut Metzler  Mathieu Roskosz  Caroline Smith  Meenakshi Wadhwa  Linda Welzenbach‐Fries  Toru Yada  Akira Yamaguchi  Ryan A. Zeigler  Michael Zolensky 《Meteoritics & planetary science》2019,54(7):1397-1400

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Cretaceous tectonic events in the border regions between the Asian continent and the proto-Pacific     

Hakuyu Okada and  Takashi Sakai 《Island Arc》1999,8(3):335-335

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MOS-1/1b MESSR Observations of the Antarctic Sea Ice: Ice Bands and Ice Streamers     

Kunimitsu Ishida  Kay I. Ohshima  Takashi Yamanouchi  Hiroshi Kanzawa 《Journal of Oceanography》1999,55(3):417-426

Meso- or submeso-scale features of the Antarctic sea ice are investigated using the MOS-1/1b MESSR Images (spatial resolution of approximately 50 m) received at Syowa Station. Particular attention is paid to the ice bands and ice streamers in coastal polynyas. In the Antarctic Ocean, ice bands can be often seen not only at the ice edge but also in the ice interior zone throughout the year and they extend for hundreds of kilometers in the latitudinal direction. It is found that the width and spacing of ice bands tend to decrease from winter to summer. The width of ice band is about 2–6 km in August and September, and 0.1–0.7 km in December. The spacing of ice bands is about 3–10 km in August and September, and 0.1–2 km in December. In coastal polynyas, ice streamers, which are composed of new ice, are sometimes observed. In general, the row of the streamers is spaced at 0.5–2 km with a width of 0.1–1.0 km.  相似文献