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141.
142.
Mamoru Saitō Shusaku Kawabata Keiich Saijo Hideo Sato 《Astrophysics and Space Science》1984,99(1-2):269-272
Epsilon Aurigae has been observed during ingress and totality between 1982 and 1983 at Okayama. Analyses of profiles of H line and of radial velocities of neutral hydrogen and metals show that the secondary component consists of at least three parts in structure.Paper presented at the Lembang-Bamberg IAU Colloquium No. 80 on Double Stars: Physical Properties and Generic Relations, held at Bandung, Indonesia, 3–7 June, 1983. 相似文献
143.
Studies are made on the structural damage at the Ashiyahama residential high‐rise steel building complex due to the Hyogo‐ken Nanbu Earthquake (Kobe Earthquake), which occurred on 17 January 1995. The axial breakage of very thick‐plated steel columns of the mega‐structure is unprecedented and has been attracting the special attention of structural engineers. The cause of the damage is first investigated from numerical computation with recourse to an explicit method of dynamic analysis based on a continuous medium. The numerical result is compared with that obtained from a conventional multi‐mass lumped stiffness model combined with an equivalent lateral‐force procedure. By comparing both the numerical results, the latter conventional method is shown to be inadequate for achieving earthquake‐resistant capability. The destructive power of the ground motion is found to have exceeded the horizontal earthquake‐resistant capacity that is prescribed in the structural design criteria. Great axial stresses are produced in columns by combined action of bending moment and axial force due to overturning moment. The fracture of heavy steel columns is caused from only the horizontal component of seismic ground motion. Actual locations of significant damage are closely related to the occurrence of plastic hinges in the analysis. It is emphasized as a warning to avoid yielding concentration in particular storeys. Lastly, recommendations to enhance earthquake‐resistant design are proposed from a practical point of view. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
144.
We have examined the vertical distributions of planktonic bivalve larvae, particularly the clam Ruditapes philippinarum and the mussel Musculista senhousia which are common and abundant on tidal flats of eastern Ariake Bay, southern Japan. Submersible pumping gear was used to
take samples at 2 stations every 2 hours during the spring tide over a whole tidal cycle and/or through daytime and nighttime.
Water samples were pumped up from 3 to 5 depths from the surface to sea bottom. Regardless of tidal cycles, D-shaped larvae
were concentrated near the surface, while umbo larvae were found at the surface to intermediate depths. On average, these
larval densities were significantly higher at the station close to the shore than the offshore station, with no significant
difference between daytime and nighttime and between flood and ebb tides at each station. The velocity and direction of water
movement at both stations revealed remarkable difference between the surface and bottom waters. The larvae at the surface
may quickly disperse and be transported elsewhere, while those in water close to the sea bottom may tend to be retained. 相似文献
145.
Hideo Kawai 《Journal of Oceanography》1985,41(3):157-166
To area-average the horizontal divergence and the vertical component of vorticity, three methods are proposed and examined. The polygon method is based on deformations of a polygon made by connecting drifters. They are deployed at widely different scales of 1 cm– 1,000 km and tracked using various procedures. The loop method is adopted when a drifter completes at least two loops of trajectory in a tidal vortex, a ring or a gyre. Even if data for a drifter completing only one loop is available, the vorticity can be calculated. The crossing method is applied to the GEK data on the circumference of a Kuroshio ring. The data which will be used to calculate them in Part 2 are summarized in tables. Offset dispositions of positive and negative divergences or vorticities on a horizontal plane and in a water column are shown. Probably, the vertical offset of vorticities does not occur in general. The area-turnover of a polygon of drifters are discussed. Sampling time-intervals, appropriate to the scale of the area, for the polygon and loop methods are examined. A first impression of Rhines' (1979) sketch has produced a misunderstanding that the polygon method would be useless because a limited number of drifters cannot follow such a complicated deformation of the material line over a long period. It is shown that adopting a short time-scale appropriate to the length scale furnishes a practical solution to the problem. 相似文献
146.
Hideo Nakajima 《Journal of Oceanography》1984,40(5):367-370
Spectral characteristics of rapid-changing random data in the ocean are discussed. Analysis shows that, if records are approximated by saw-toothed random series 1 and step series 2, 1 and 2 generally have spectral ranges of the –4th power and –2nd power, respectively, with respect to frequency (or wave number). 相似文献
147.
Hideo Nakajima 《Journal of Oceanography》1975,31(6):227-234
Based on the observation at the Hayasui Straits, actual conditions of the tidal mixing, of two water masses separated by the strait, are investigated for the time scale shorter than the the tidal period. Analyses show that the tidal mixing of water masses occurs by the disintegration of mutually penetrating small masses of water, which have been produced by the reciprocating tidal motion of the water masses with some topographical effect, especially at the slack water as large tongues. The mutual penetration occurs rather horizontally, and some of these turbulent smaller masses of water keep their own properties for a rather long period of the order of three hours, without mixing even in the violent shear flows. Initial horizontal scale of these turbulent masses is estimated as of the order of three kilometers. These actual conditions reveal themselves as the macroscopic diffusion coefficient. 相似文献
148.
Hideo Kawai 《Journal of Oceanography》2003,59(3):303-315
Distinctive features of the repulsive bifurcation of Kuroshio and Gulf Stream jets, induced from various observations, have
been examined by equations of motion of a 1 1/2 -layer model in natural coordinates, although causes of the bifurcation are
discussed little. From the conservation of volume flux through paths above a main thermocline, we have derived the equation
M
n
K
In + M
s
K
Is = 0 for northern (n) and southern (s), steady-state curved jets, just downstream of the bifurcation from a straight jet, where M is momentum flux through the path and K
I, positive for cyclonic deflection of the streamline, is the curvature of a certain intermediate streamline in the laminar
path. Assuming concentric streamlines in the curved path, which is narrower than 1–0.5 times the radius of curvature of the
center streamline of the path, and symmetric momentum flux through a path element of unit width with respect to the center
streamline, we found that K
I approximates to the curvature averaged across the path, relative errors being <0.25−(0.25)2. Bifurcation starts with a ‘Big Bang’ and the leading turbulent front of a split jet may be unsteady, but the succeeding
laminar part can be regarded as stationary or as translating at a constant velocity, as if frozen. Thus, such features are
described by the equation. A provisional classification is given of various warm extrusions along branches of both Streams,
all of which exemplify the repulsive bifurcation, except for the mainstreams with very narrow (< 30–40 km) branches, possibly
due to misapplication of the model.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
149.
The influence ofNoctiluca's predation on theAcartia population in Ise Bay was examined by taking samples at 27 stations once a month from May to December, 1974.The copepod eggs were found inNoctiluca mainly in May and June. Considering from various spawning types of copepods, the eggs were presumed to beAcartia, the most numerous species of all copepods in the bay.Noctiluca was dominant plankton in May and June whenAcartia was abundantly distributed.Acartia eggs were found in 33.2–39.3% of individuals ofNoctiluca in May and June.Noctiluca was more frequently observed to contain one egg ofAcartia per individual. It was suggested that 55.0 eggs perAcartia female per day were eaten by theNoctiluca population in May wherease 3.5 eggs in June. It was deduced that 74% of the eggs produced byAcartia was preyed on byNoctiluca (about 5% in June). The predation byNoctiluca as well as that by the sand-eel must influence greatly to the production ofAcartia in the bay. 相似文献
150.
Vertical distributions of phyllosoma larvae were examined in waters east of the Philippines or west of the Mariana Islands
(18°56′ N to 19°04′ N; 129°10′ E to 129°35′ E) based on zooplankton samples collected with an Isaacs-Kidd Midwater Trawl on
September 22–24, 1986. Phyllosoma larvae belonged to the two families Scyllaridae and Palinuridae comprising 4 genera and
9 species. Of the collected phyllosoma larvae, those of Scyllarus cultrifer and Panulirus longipes were most abundant and showed similar vertical distributions: (1) both species were collected from the mixed layer at night
but not in the day, (2) their vertical distributions did not change with their stages, and (3) the upper limit of their vertical
distributions during the day accorded with the base of mixed layer. Furthermore, their vertical distributions were similar
to those of lepthocephalus larvae which were collected using the same sampling stations and gear in the present study. Vertical
distributions of phyllosoma larvae were discussed in relation to their horizontal distributions.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献