The coastal undercurrent— A role of longshore scales in coastal upwelling dynamics     

Kozo Yoshida 《Progress in Oceanography》1980,9(2):83-131

A simple three-dimensional model of a time-dependent coastal upwelling is discussed for time scales of several days to a week, with the linear, two-layer, flat-bottom and $\text{?-}\text{plane}$ approximation. Emphasis is placed on the effects of longshore scales determined by the longshore variabilities in the wind stress distributions. The responses of the inshore motions are shown to depend critically on the longshore scales. For a certain wide range of the scales, the system reveals dominantly baroclinic responses and a full development of the poleward coastal undercurrent without β effect. Somewhat detailed discussions are given on the coastal upwelling, the coastal jet and the poleward undercurrent, which are interpreted simply as the orbital velocities of the forced Kelvin-type waves.  相似文献   

Some thoughts on the Cold Eddy south of Enshunada     

Henry Stommel  Kozo Yoshida 《Journal of Oceanography》1971,27(5):213-217

On the basis of the results confirmed in the new volume Kuroshio, a figure is presented on subsurface temperature arranged chronologically for the selected one-degree square to clearly document the bimodal state of the Kuroshio in this area. To extend this analysis of the state further into the non-documented past, a preliminary survey is attempted with the data on air and sea-temperatures at Hachijojima of these 45 years. As may be anticipated, those data are found to bear little in-phase correlation with the Cold Eddy, though they might prove useful after further analysis. Some ideas of analyzing tree-rings on Hachijojima and shallow sea sediments are also discussed in this connection.  相似文献   

Wide field X-ray monitor on board the High Energy Transient Experiment (HETE)     

A. Yoshida  M. Matsuoka  N. Kawai  F. Tokanai  E. E. Fenimore  J. J. M. In 'T Zand  M. Galassi  M. Yamauchi  K. Takagishi  I. Hatsukade 《Astrophysics and Space Science》1995,231(1-2):463-466

The High-Energy Transient Experiment (HETE) is designed for the multiwavelengths study of Gamma-Ray Bursts (GRBs) in UV, X-ray and gamma-ray range with three scientific instruments. The X-ray instrument, Wide-field X-ray Monitor (WXM), consists of four units of one-dimensional position sensitive gas proportional counters and two perpendicularly oriented one-dimensional coded apertures. The WXM has a wide FOV of 1.5 steradian together with the capability to locate GRBs with 10 arcmin accuracy, and covers photon energies of 2 to 25 keV with an energy resolution of typically 18 % at 6 keV, measuring wide band spectra together with the gamma-ray spectrometer (FREGATE). The coded X-ray image will be deconvolved on board and the GRB location will be provided to the UV camera within 1 sec . GRB locations will also be broadcast in real time to ground-based observers for follow-up observations.  相似文献   

Strain and stress changes in the Tokai region of central Japan expected from a 3D subduction model     

Hidekuni Kuroki  Hidemi M ItoAkio Yoshida 《Physics of the Earth and Planetary Interiors》2003,135(4):231-252

Using a 3D simulation model with a rate- and state-dependent friction law, Kuroki et al. (2002) discussed a process of a hypothetical great earthquake in the Tokai region, where the Philippine Sea plate subducts beneath the Eurasian plate. One of the main concerns was characteristic changes in volumetric strain and displacement on the ground surface which are caused by the evolution of the coupling between the two plates, i.e. evolution of a strongly coupled region between the plates which results in a preslip of the earthquake.In the present paper we discuss other observable phenomena which might help us to identify the stage of the coupling. The preslip of the earthquake could be more effectively detected by using full information about the change of strain rather than volumetric strain alone; the change in rotation angle of principal strain axes should amount to several tens of degrees while the order of the change in volumetric strain is 10⁻⁸ to 10⁻⁷ for 1 day before the earthquake. The spatial pattern of the displacement field on the ground surface provides us with information on the intermediate-term precursory changes in the plate coupling. Information given by micro-earthquakes is less direct. The seismicity should change considerably when a highly shear-stressed ring on the plate interface passes nearby, and ups and downs of seismicity rate will be estimated by Coulomb failure stress. On the other hand, focal mechanisms are rather insensitive to the progress of plate subduction. The changes may be not significant even at the time of the preslip. The interplate coupling yields a stress field that should produce reverse fault type mechanisms, but the stress field is modulated by a curved shape of the plate interface. Superposition of a regional tectonic stress to this field explains observed spatial distribution of focal mechanisms in the Tokai region which involve large strike-slip components.  相似文献   

Experimental verification of torsional response control of asymmetric buildings using MR dampers     

Osamu Yoshida  Shirley J. Dyke  Luca M. Giacosa  Kevin Z. Truman 《地震工程与结构动力学》2003,32(13):2085-2105

This paper proposes a semiactive control system to reduce the coupled lateral and torsional motions in asymmetric buildings subjected to horizontal seismic excitations. Magnetorheological (MR) dampers are applied as semiactive control devices and the control input determination is based on a clipped‐optimal control algorithm which uses absolute acceleration feedback. The performance of this method is studied experimentally using a 2‐story building model with an asymmetric stiffness distribution. An automated system identification methodology is implemented to develop a control‐oriented model which has the natural frequencies observed in the experimental system. The parameters for the MR damper model are identified using experimental data to develop an integrated model of the structure and MR dampers. To demonstrate the performance of this control system on the experimental structure, a shake table is used to reproduce an El Centro 1940 N–S earthquake as well as a random white noise excitation. The responses for the proposed control system are compared to those of passive control cases in which a constant voltage is applied to the MR damper. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Fourth Nepal Geological Congress     

Masaru Yoshida  Takeshi Imayama  Ranjan K. Dahal 《Gondwana Research》2004,7(4):1249-1251

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The Central Africa Copperbelt in Southeastern Democratic Republic of Congo: IGCP-450 Field Workshop on Proterozoic Sediment-hosted Base Metal Deposits of West Gondwana     

M. Yoshida  J. Kokonyangi  J. Batumike 《Gondwana Research》2004,7(2):640-643

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The Central Granites-Gneiss-Migmatite Belt (CGGMB) of Madagascar: the Eastern Neoproterozoic Suture of the East African Orogen   总被引：1，自引：0，他引：1  

R.A. Rambeloson  M. Yoshida  V. Ramasiarinoro  L. Le Duc  B. Ralison 《Gondwana Research》2003,6(4):641-651

The northeastern part of Madagascar is characterized by Archaean to early Proterozoic rocks composed principally of Archaean granite and greenstone/amphibolite as well as reworked migmatite with subordinate Proterozoic paragneisses. The southern part is mostly occupied by Proterozoic rocks, composed mostly of Meso to Neo-Proterozoic and less metamorphic metasediments (Itremo Group) in the northwest, para- and ortho-gneisses in most other areas, with minor granitic gneisses with some Archaean components in the southeast. The north-northwest trending Central Granite-Gneiss-Migmatite Belt (CGGMB) is situated at the western margin of the Archaean-early Proterozoic terrain. The CGGMB is composed of granite, gneiss and migmatite with distinct lithologies and structures. They are: i) many types of granites including alkaline to mildly alkaline granites, and calc-alkaline granites; ii) batholitic granites, migmatitic granites and granite dyke swarm, iii) eclogite, and iv) the Ankazobe-Antananarivo-Fianarantsoa Virgation.

The CGGMB was formed by the collision of the palaeo-Dharwar Craton to the east and the East African Orogen to the west at ca. 820-720 Ma and suffered indentation by a part of the western part of the East African Orogen at ca. 530 Ma that produced the Ankazobe-Antananarivo-Fianarantsoa Virgation at the centre of the CGGMB. Thus, the CGGMB is proposed to be the continuation of the eastern suture between the palaeo Dharwar Craton and the East African Orogen, and carries the main feature of the Pan-African collisional event in Madagascar.  相似文献   

A Report of IGCP-368 Activities and its Future Programs     

Masaru Yoshida 《Gondwana Research》1998,1(3-4):421-423

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Boron isotopic composition of fumarolic condensates and sassolites from Satsuma Iwo-jima,Japan   总被引：1，自引：0，他引：1  

Tadao Kanzaki  Minoru Yoshida  Masao Nomura  Hidetake Kakihana  Takejiro Ozawa 《Geochimica et cosmochimica acta》1979,43(11):1859-1863

¹¹B/¹⁰B ratios of the high temperature fumarolic gases (>465°C) of this island were found to be constant within the limits of experimental error (¹¹B/¹⁰B = 4.066). This value may represent the ¹¹B/¹⁰B ratio of boron in the andesite magma. ¹¹B/¹⁰B ratios of the low temperature fumarolic gases (<235°C) were found to vary from 4.053 to 4.077. ¹¹B/¹⁰B ratios of some sassolites were approximately equal to that of the fumarolic condensates and the other ones were slightly enriched in ¹⁰B compared to the fumarolic condensates.  相似文献