Further evidence of normal mode Rossby waves     

Toshihiko Hirooka  Isamu Hirota 《Pure and Applied Geophysics》1989,130(2-3):277-289

Further observational evidence of normal mode Rossby waves with higher meridional mode numbers is presented with the aid of global data from the troposphere to the stratosphere over the period November 1979 through April 1986.It is shown, without using ana priori assumption of meridional structure, that the third antisymmetric modes of zonal wavenumbers 1 and 2,i.e., (1,4) and (2,4) modes, substantially exist in the real atmosphere. These modes are, however, easily influenced by the nonuniform background field even in the equinoctial season; amplitude submaxima near the equator are apt to be dubious in the upper stratosphere so that the prototype meridional structure becomes obscure. The period of the (1,4) mode often falls into that of the (1,3) mode, about 16 days. Hence, these two modes cannot be classified simply by their periods, but the separation is made by their meridional structure.An appearance calendar of various modes is also presented for the analysis period. It is found that each mode appears irregularly throughout the year and that the year-to-year variation is fairly large.  相似文献   

Multiple-rind structure in pillow lava as an indicator of shallow water     

Yosuke Kawachi  Ian J. Pringle 《Bulletin of Volcanology》1988,50(3):161-168

Multiple-rind structure is common among shallow-water pillows with diameters larger than about 1 m in Oamaru, New Zealand, on the Columbia Plateau (USA), and elsewhere. A rind consists of sideromelane, tachylyte, and tachylytic basalt. A multiple rind is a concentric set of repeated rinds in various forms, e. g., a portion of a broken rind thrust under another part, a series of short and detached subparallel rinds, or a pouch-shaped depression. Transitions and combinations of these three forms are common. Multiple-rind structure develops at any part of the pillow perimeter, but does not cover the pillow completely. It is always accompanied by a rupture in the outermost rind. Up to 13 rinds have been observed, but two to four rinds are most common. The multiple-rind structure is formed by implosion resulting from condensation of exsolved H₂O. When H₂O condenses, a pressure difference between the interior and exterior of a pillow is created. Above a certain threshold pressure difference, the outer skin of a pillow is torn at weak points, such as radial joints, and thrusts under the neighboring skin, buckles to form a pouch-shaped depression, or produces some variation of these. One set of multiple rinds is thus formed. Further exsolution and condensation of H₂O in solidifying pillows may cause development of additional rinds. H₂O exsolution and condensation and subsequent implosion are limited to low-pressure environments so that multiple-rind structure is characteristic of shallow-water pillow lava.  相似文献   

The period–luminosity relation for type II Cepheids in globular clusters     

Noriyuki Matsunaga  Hinako Fukushi  Yoshikazu Nakada  Toshihiko Tanabé  Michael W. Feast  John W. Menzies  Yoshifusa Ita  Shogo Nishiyama  Daisuke Baba  Takahiro Naoi  Hidehiko Nakaya  Takahiro Kawadu  Akika Ishihara  Daisuke Kato 《Monthly notices of the Royal Astronomical Society》2006,370(4):1979-1990

We report the result of our near-infrared observations ( JHK _s) for type II Cepheids (including possible RV Tau stars) in galactic globular clusters. We detected variations of 46 variables in 26 clusters (10 new discoveries in seven clusters) and present their light curves. Their periods range from 1.2 d to over 80 d. They show a well-defined period–luminosity relation at each wavelength. Two type II Cepheids in NGC 6441 also obey the relation if we assume the horizontal branch stars in NGC 6441 are as bright as those in metal-poor globular clusters in spite of the high metallicity of the cluster. This result supports the high luminosity which has been suggested for the RR Lyr variables in this cluster. The period–luminosity relation can be reproduced using the pulsation equation     assuming that all the stars have the same mass. Cluster RR Lyr variables were found to lie on an extrapolation of the period–luminosity relation. These results provide important constraints on the parameters of the variable stars.
Using Two Micron All-Sky Survey (2MASS) data, we show that the type II Cepheids in the Large Magellanic Cloud (LMC) fit our period–luminosity relation within the expected scatter at the shorter periods. However, at long periods (   P > 40  d, i.e. in the RV Tau star range) the LMC field variables are brighter by about one magnitude than those of similar periods in galactic globular clusters. The long-period cluster stars also differ from both these LMC stars and galactic field RV Tau stars in a colour–colour diagram. The reasons for these differences are discussed.  相似文献   

An experimental study on Fischer‐Tropsch catalysis: Implications for impact phenomena and nebular chemistry     

Yasuhito SEKINE  Seiji SUGITA  Takafumi SHIDO  Takashi YAMAMOTO  Yasuhiro IWASAWA  Toshihiko KADONO  Takafumi MATSUI 《Meteoritics & planetary science》2006,41(5):715-729

Abstract— Fischer‐Tropsch catalysis, by which CO and H₂ are converted to CH₄ on the surface of transition metals, has been considered to be one of the most important chemical reactions in many planetary processes, such as the formation of the solar and circumplanetary nebulae, the expansion of vapor clouds induced by cometary impacts, and the atmospheric re‐entry of vapor condensate due to asteroidal impacts. However, few quantitative experimental studies have been conducted for the catalytic reaction under conditions relevant to these planetary processes. In this study, we conduct Fischer‐Tropsch catalytic experiments at low pressures (1.3 times 10^?4 bar ≤ P ≤ 5.3 times 10^?1 bar) over a wide range of H₂/CO ratios (0.25–1000) using pure iron, pure nickel, and iron‐nickel alloys. We analyze what gas species are produced and measure the CH₄ formation rate. Our results indicate that the CH₄ formation rate for iron catalysts strongly depends on both pressure and the H₂/CO ratio, and that nickel is a more efficient catalyst at lower pressures and lower H₂/CO ratios. This difference in catalytic properties between iron and nickel may come from the reaction steps concerning disproportionation of CO, hydrogenation of surface carbon, and the poisoning of the catalyst. These results suggest that nickel is important in the atmospheric re‐entry of impact condensate, while iron is efficient in circumplanetary subnebulae. Our results also indicate that previous numerical models of iron catalysis based on experimental data at 1 bar considerably overestimate CH₄ formation efficiency at lower pressures, such as the solar nebula and the atmospheric re‐entry of impact condensate.  相似文献   

Variable stars in the Magellanic Clouds – II. The data and infrared properties     

Yoshifusa Ita †  Toshihiko Tanabé  Noriyuki Matsunaga  Yasushi Nakajima  Chie Nagashima  Takahiro Nagayama  Daisuke Kato  Mikio Kurita  Tetsuya Nagata  Shuji Sato  Motohide Tamura  Hidehiko Nakaya  Yoshikazu Nakada 《Monthly notices of the Royal Astronomical Society》2004,353(3):705-712

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Assessing decarbonization pathways and their implications for energy security policies in Japan     

Ken Oshiro  Mikiko Kainuma  Toshihiko Masui 《Climate Policy》2016,16(4):S63-S77

For countries without sufficient fossil fuel resources such as Japan, climate policies in the mid- to long term need to satisfy requirements not only for decarbonisation but also for energy security in the context of limitations on renewable energies and nuclear power. This study assesses the feasibility of decarbonization pathways to 2050 and their effects on energy security, considering the latest energy and climate policies in Japan using the AIM/Enduse model. The analysis illustrates that deep decarbonization by 2050 is technically feasible even without nuclear power based on three elements: energy efficiency improvements, low-carbon electricity and electrification in end-use sectors. These decarbonization pathways, in the long term, could also contribute to enhanced energy security, reducing import dependency to less than a half of the total primary energy and reducing import bills for fossil fuels by around 70% compared with the current level. Notably, renewable energies could play a strategically significant role in satisfying both climate and energy security requirements. In the mid-term (to 2030), however, although GHG emissions are reduced by 14–20% from 1990 levels, import dependency is relatively stable at today's levels, particularly without the restart of nuclear power. Given the limited potential for renewable energies in the mid-term, it is suggested that the availability of nuclear power will have negative impacts on carbon intensity and energy security, and policies to enhance the security of fossil fuels, including diversification of fuel sources and supply routes, will be required for the foreseeable future.

Policy relevance

Considering the scarcity of indigenous fossil fuel resources and the uncertain availability of nuclear power in Japan, renewable energy could play a strategically significant role in replacing unabated fossil fuels, which would contribute to satisfying both climate and energy security requirements in the long term. However, the renewable energy potential is insufficient to eliminate the requirement for fossil fuels by 2030; therefore the unavailability of nuclear power would affect energy security considerably. Thus, policies in the mid-term would still require enhancement of the energy security of fossil fuels, including the diversification of fuel sources and supply routes, as well as alleviation of the impacts of price volatility.  相似文献   

Evidence of thermal pressurization in high‐velocity friction experiments on smectite‐rich gouges     

Fabio Ferri  Giulio Di Toro  Takehiro Hirose  Toshihiko Shimamoto 《地学学报》2010,22(5):347-353

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Deep-sea submersible survey in the Suruga, Sagami and Japan Trenches: preliminary results of the 1985 Kaiko cruise, Leg 2     

Guy Pautot  Kazuaki Nakamura  Philippe Huchon  Jacques Angelier  Jacques Bourgois  Kantaro Fujioka  Toshihiko Kanazawa  Yasuo Nakamura  Yujiro Ogawa  Michel Sguret  Akira Takeuchi 《Earth and Planetary Science Letters》1987,83(1-4)

Nine submersible dives were made in three trenches off central Japan, between 2990 and 5900 m of water depth. Our observations confirm the interpretation that Daiichi-Kashima Seamount is a Cretaceous guyot formed on the Pacific plate that has traveled into the Japan Trench. We also confirmed the previous interpretation of a large normal fault that splits the seamount in two halves, the lower one being now subducting beneath the Japan margin. Compressional deformation was identified within the lower part of the inner slope in front of the seamount. The pattern of deformation that affects Quaternary sediments is in agreement with the present kinematics of the convergence between the Pacific plate and Japan. Deep-water (5700 m) clam colonies are associated with advection of fluids, driven by the subduction-related overpressures. In the northern slope of the Boso Canyon, along the Sagami Trough system (Philippine Sea plate-Japan boundary), the deformation affecting a thick upper Miocene to lower Pliocene sequence indicates two directions of shortening: a N175°E direction which is consistent with the present relative motion along the Sagami Trough (N285–N300°E) and a N30°E direction which could be related to a more northerly direction of convergence that occured during the early Quaternary and earlier.  相似文献   

Earthquake design considerations in reinforced concrete columns     

Toshihiko Hisada  Nobutsugu Ohmori  Satoshi Bessho 《地震工程与结构动力学》1972,1(1):79-91

Damages resulting from the Tokachi-Oki earthquake of 1968 demonstrated that many code-designed reinforced concrete columns do not have adequate earthquake resistance. A review of Japanese research revealed that the axial force ratio, the moment arm ratio, and the type and ratio of transverse reinforcement control the resistance and ductility of concrete columns. A recent experimental study at the Kajima Institute of Construction Technology evaluated the resistance of columns with three types of transverse reinforcement and three reinforcement ratios subjected to repeated alternating loads. Tied and spiral columns proved to be superior to hooped columns.  相似文献   

Mesoscale current fluctuations observed in the deep western North Pacific     

Shiro Imawaki  Keisuke Taira  Toshihiko Teramoto 《Journal of Oceanography》1984,40(1):39-45

A set of simultaneous long-term, deep current measurements was taken using a moored array in the mid-ocean of the western North Pacific near 30°N, 146°E. Five current meters at three stations provided good quality records over 84 days. Low-frequency current fluctuations with meridional dominance are clearly seen in the deep layer records. They are consistent with signals of a mesoscale current fluctuation which has a period of about 100 days, an east-west wave length of about 200 km, and a westward phase propagation with a speed of about 2 cm sec^–1. Bottom intensification of the east component of low-frequency current fluctuations is also observed.  相似文献