http://www.sciencedirect.com/science/article/pii/S1674987114001108     

Masaki Yoshida 《地学前缘(英文版)》2015,6(1):1-2

<正>About three decades after the establishment of the plate tectonics theory in the late 1960s,Maruyama(1994)proposed the"plume tectonics"theory based on whole-mantle seismic tomography image(Fukao,1992;Fukao et al.,1994).According to this theory,the earth's interior is divided into three regimes:the earth's surface region governed by lateral motions of tectonic plates,the mantle governed by vertical motions of"superplumes"(i.e.,large-  相似文献   

Frost heaving in ballast railway tracks     

Satoshi Akagaw  Michiaki Hori 《寒旱区科学》2015,7(5):632-636

Frost heaving is a well-known phenomenon in cold regions, which may occur in wet clayey grounds during winter. Railway track upheaval occurring in cold regions during the winter is generally understood as frost heaving in the subgrade layer. However, it has been confirmed that upheaval due to frost heaving sometimes occurs in the ballast layer. This understanding has been observed in active railways in northern Japan. The samples collected from ballast and subgrade layers have been examined for frost heave susceptibilities and confirmed that ballast layers which contain fines may heave.  相似文献   

The inner solar system cratering record and the evolution of impactor populations   总被引：1，自引：0，他引：1  

Robert G.Strom  Renu Malhotra  Zhi-Yong Xiao  Takashi Ito  Fumi Yoshida  Lillian R Ostrach 《天文和天体物理学研究(英文版)》2015,(3):407-434

We review previously published and newly obtained crater size-frequency distributions in the inner solar system. These data indicate that the Moon and the terrestrial planets have been bombarded by two populations of objects. Population 1,dominating at early times, had nearly the same size distribution as the present-day asteroid belt, and produced heavily cratered surfaces with a complex, multi-sloped crater size-frequency distribution. Population 2, dominating since about 3.8–3.7 Gyr,had the same size distribution as near-Earth objects(NEOs) and a much lower impact flux, and produced a crater size distribution characterized by a differential –3single-slope power law in the crater diameter range 0.02 km to 100 km. Taken together with the results from a large body of work on age-dating of lunar and meteorite samples and theoretical work in solar system dynamics, a plausible interpretation of these data is as follows. The NEO population is the source of Population 2 and it has been in near-steady state over the past ～ 3.7–3.8 Gyr; these objects are derived from the main asteroid belt by size-dependent non-gravitational effects that favor the ejection of smaller asteroids. However, Population 1 was composed of main belt asteroids ejected from their source region in a size-independent manner, possibly by means of gravitational resonance sweeping during orbit migration of giant planets;this caused the so-called Late Heavy Bombardment(LHB). The LHB began some time before ～3.9 Gyr, peaked and declined rapidly over the next ～ 100 to 300 Myr,and possibly more slowly from about 3.8–3.7 Gyr to ～2 Gyr. A third crater population(Population S) consisted of secondary impact craters that can dominate the cratering record at small diameters.  相似文献   

Detection of large color variation in the potentially hazardousasteroid （297274） 1996 SK     

Chien-Hsien Lin  Wing-Huen Ip  Zhong-Yi Lin  Fumi Yoshida  Yu-Chi Cheng 《中国天文和天体物理学报》2014,(3):311-318

Low-inclination near-earth asteroid(NEA)(297274) 1996 SK,which is also classified as a potentially hazardous asteroid,has a highly eccentric orbit.It was studied by multi-wavelength photometry within the framework of an NEA color survey at Lulin Observatory.Here,we report the finding of large color variation across the surface of(297274) 1996 SK within one asteroidal rotation period of4.656 ± 0.122 hours and classify it as an S-type asteroid according to its average colors of B- V = 0.767 ± 0.033,V- R = 0.482 ± 0.021,V- I = 0.801 ± 0.025and the corresponding relative reflectance spectrum.These results might be indicative of differential space weathering or compositional inhomogeneity in the surface materials.  相似文献   

Scatterer density estimation in the crust by seismic array processing     

Satoshi Matsumoto 《Geophysical Journal International》2005,163(2):622-628

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Instruments, Detectors and the Future of Astronomy with Large Ground Based Telescopes     

Douglas A. Simons  Paola Amico  Dietrich Baade  Sam Barden  Randall Campbell  Gert Finger  Kirk Gilmore  Roland Gredel  Paul Hickson  Steve Howell  Norbert Hubin  Andreas Kaufer  Ralf Kohley  Philip MacQueen  Sergej Markelov  Mike Merrill  Satoshi Miyazaki  Hidehiko Nakaya  Darragh O'Donoghue  Tino Oliva  Andrea Richichi  Derrick Salmon  Ricardo Schmidt  Hongjun Su  Simon Tulloch  Maria Luisa García Vargas  R. Mark Wagner  Olivier Wiecha  Binxun Ye 《Experimental Astronomy》2005,19(1-3):15-44

Results of a survey of instrumentation and detector systems, either currently deployed or planned for use at telescopes larger than 3.5 m, in ground based observatories world-wide, are presented. This survey revealed a number of instrumentation design trends at optical, near, and mid-infrared wavelengths. Some of the most prominent trends include the development of vastly larger optical detector systems (> 10⁹ pixels) than anything built to date, and the frequent use of mosaics of near-infrared detectors – something that was quite rare only a decade ago in astronomy. Some future science applications for detectors are then explored, in an attempt to build a bridge between current detectors and what will be needed to support the research ambitions of astronomers in the future.  相似文献   

Exponential instability of collision orbit in the anisotropic Kepler problem     

Haruo Yoshida 《Celestial Mechanics and Dynamical Astronomy》1987,40(1):51-66

The straight-line collision solution in the anisotropic Kepler problem is extended to a periodic solution by means of Sundman's analytic continuation. It is shown that this collision periodic solution is always exponentially unstable.  相似文献   

Microscopic filamentation due to electrothermal instability and plasma heating in time-dependent solar transition layer     

Satoshi Hinata 《Solar physics》1988,116(2):239-258

We have investigated nonlinear equilibrium states of a microscopic current filamentation (electrothermal instability) in solar atmosphere. The microscopic filamentation instability will develop for transition zone ion temperature plasmas, provided T _e/T_i > 1, where T _e and T _i are the electron and ion temperatures, respectively. Since the temperature radio for a steady-state solar atmosphere is approximately unity, the electrothermal instability will develop only in a time-dependent solar atmosphere. Indeed, such a condition is provided by time-dependent currents, which seem to exist in many magnetic loops as recent analysis by Porter et al. (1987) indicates. When the onset condition for the electrothermal instability is satisfied, the instability drives a current filamentation to a nonlinear equilibrium state with a spatially periodic electron temperature variation with the wavelength comparable to several ion-Larmor radii. The amplitude of the periodic temperature variation may be so large that the transition layer temperature and coronal temperature plasmas may exist within several Larmor radii — coexistence of the transition zone and corona within the same macro-volume.  相似文献   

A note on Kowalevski exponents and the non-existence of an additional analytic integral     

Haruo Yoshida 《Celestial Mechanics and Dynamical Astronomy》1988,44(4):313-316

In Hamiltonian systems with a homogeneous rational potential and two degrees of freedom, the presence of imaginary Kowalevski exponents implies the non-existence of an additional analytic integral, i.e., non-integrability of the system.  相似文献   

Geochemical and isotopic characteristics of the Cretaceous Orikabe Plutonic Complex,Kitakami Mountains,Japan: magmatic evolution in a zoned pluton and significance of a subduction-related mafic parental magma     

Masumi?Ujiie?MikoshibaEmail author  Satoshi?Kanisawa  Yukihiro?Matsuhisa  Shigeko?Togashi 《Contributions to Mineralogy and Petrology》2004,146(4):433-449

The Orikabe Plutonic Complex, northeast Japan, is a zoned pluton and one of the Cretaceous intrusions in the Circum-Pacific area. In the Main body, K-rich calc-alkaline rocks composed of marginal gabbro and a large amount of monzodiorite–quartz monzonite–monzogranite are intruded successively by innermost calc-alkaline rocks of granodiorite. The gabbro and monzodiorite–monzogranite have a continuous chemical variation, while the granodiorite has lower concentrations of K, Rb, Y, Zr, Nb and F at the same SiO₂ content. The gabbro and monzodiorite–quartz monzonite have a Rb-Sr whole-rock age of 119±12 Ma with an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.70392±0.00007. The initial ⁸⁷Sr/⁸⁶Sr ratio of the innermost granodiorite is estimated to be about 0.7042. The ¹⁸O values of fresh rocks range from +6.7 to +8.3, indicating a positive correlation with SiO₂ contents. The K-rich calc-alkaline rocks were derived through fractional crystallization from a mafic parental magma with a slightly high ¹⁸O value, implying a major contribution of a sub-arc mantle at a continental margin. Trace element modeling indicates that the source could have been a fertile lherzolite enriched in LILE and depleted in HFSE. The innermost granodiorite was the differentiation product of a distinct parental magma, suggesting the involvement of a small amount of crustal component in the source and partial melting under a more hydrous condition.Editorial responsibility: J. Hoefs  相似文献