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271.
Toru Kobari Hiroyasu Akamatsu Masato Minowa Toshihiro Ichikawa Kazuo Iseki Ryuji Fukuda Masataka Higashi 《Journal of Oceanography》2010,66(5):673-684
Seasonal changes in the shape and size composition of fecal pellets were investigated with sediment trap samples from 50 and
150 m in Kagoshima Bay to evaluate how the mesozooplankton community affects fecal pellet flux. Deep vertical mixing was evident
in March, and thermal stratification was developed above 50 m in June, August and November. Chlorophyll a, suspended particulate organic carbon (POC) and copepod abundance were uniform throughout the water column during the seasonal
mixing and concentrated above 50 m in the stratified seasons. Calanoids were the most predominant copepods in March and poecilostomatoids
composed more than 45% of the copepod community in June, August and November. Fecal pellet fluxes at 50 and 150 m were the
highest in March, nearly half of POC flux. The relative contribution declined considerably in the other months, especially
for less than 4% of POC flux in August. The decline was corresponded to the predominance of cyclopoids and poecilostomatoids.
Cylindrical pellets dominated the fecal matters at both depths throughout the study period, while larger cylindrical pellets
nearly disappeared at 150 m in June, August and November. Copepod incubation revealed that cylindrical and oval pellets were
egested by calanoids and the other copepods, respectively. We suggest that cylindrical fecal pellets produced by calanoid
copepods contribute to feces flux but the predominance of poecilostomatoids and/or cyclopoids decreases feces flux via the
increase of oval pellets and fragmentation of larger cylindrical pellets. 相似文献
272.
N. Tamura G. J. Murray P. Luke C. Blackburn D. J. Robertson N. A. Dipper R. M. Sharples J. R. Allington-Smith 《Experimental Astronomy》2003,15(1):1-12
We present results from cryogenic tests of a Volume-Phase Holographic(VPH) grating at 200 K measured at near-infrared wavelengths.
The aims of these tests were to see whether the diffraction efficiency and angular dispersion of a VPH grating are significantly
different at a low temperature from those at a room temperature, and to see how many cooling and heating cycles the grating
can withstand. We have completed 5 cycles between room temperature and 200 K, and find that the performance is nearly independent
of temperature, at least over the temperature range which we are investigating. In future, we will not only try more cycles
between these temperatures but also perform measurements at a much lower temperature (e.g., ∼80 K). 相似文献
273.
The center-to-limb variation of the excess intensity in faculae was obtained for 266 active regions with an accuracy of 10–3. For this observation full-disk images were obtained with a rotating one-dimensional diode array whose rotation axis was set at the disk center, at the wavelength of 5450 Å with a bandpass of 400 Å. From the center-to-limb variation of excess intensity of active regions the excess effective temperature was found to be 6.4 K on the average where the mean longitudinal magnetic field is 65 G as measured by 5233 Å line. In other words the ratio of the excess radiative flux to the total flux was 0.44% on the average for the present measurements of low spatial resolution of 20.The average excess intensity for 60 active regions near the disk center was found to be 4 × 10–4 of the quiet Sun intensity. This very low excess brightness averaged over the whole active region, in contrast to the reported high excess brightness of facular points (diameter 0.2) of 0.4, leads to a hypothesis that the background in between facular points in the active region is darker than the true quiet photosphere by 1%. It is further surmised that the inferred darkness of intra facular points is due to partial compensation for excess total irradiance of facular points. This interpretation is also consistent with previous observations of the contrast of facular points near the limb. 相似文献
274.
A method to cover a tunnel lining with a soft and thin coating is discussed herein as a possible measure for mitigating seismic damage to tunnels. Long‐term earthquake observations at different tunnel sites within a variety of alluvial soil deposits have demonstrated that a circular tunnel is liable to deform in such a way that its two diagonal diameters crossing each other expand and contract alternately. Narrowing down vibration modes, in order to discuss this particular and the most important mode, any of the essential items of the soil–tunnel system, namely the soil, the coating and the tunnel lining, has only one degree of freedom, allowing the coating effect to be simply evaluated in terms of a limited number of key parameters. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
275.
We have measured polarization of the 1.1 mm and 0.8 mm continuum emission for 3 pre-T Tauri stars and 2 T Tauri stars. Positive detections were made for NGC 1333 IRAS 4 and IRAS 16293-2422, while L1551 IRS 5 and HL Tau were only marginally detected. For GG Tau we measured a 2 upper limit of 3%. The polarization is interpreted in terms of thermal emission by magnetically aligned dust grains in circumstellar disks or envelopes. We have found a definite geometrical relation between the polarization and other circumstellar structure. 相似文献
276.
Shigeru Aoki Kazuo Shibuya Akihiro Masuyama Taku Ozawa Koichiro Doi 《Journal of Oceanography》2002,58(3):519-523
Global Positioning System (GPS) measurements of the vertical displacement of fast ice near Syowa Station, Antarctica, were
conducted between April and December 1998 to evaluate measurements of sea level variation derived with a conventional bottom
pressure gauge (BPG). The BPG-derived sea level revealed a seasonal variation of about 0.13 m, with a high in April–June and
a low in November–December. The GPS-derived sea level, combined with observed sea ice thickness, supported the BPG result,
with an RMS error of 0.007 m. Our result also demonstrates that GPS is a powerful technique for monitoring sea level variations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
277.
278.
Shinjiro Mizuno Kazuo Kawatate Tomoki Nagahama Tsunehiro Miita 《Journal of Oceanography》1989,45(6):375-384
The Tushima Current in the east channel was measured in a site of the strong current between Tushima and Iki Islands for 43 days of the winter in 1986. The primary results are:First, it was highly barotropic and flowed northeastward with a mean speed of about 20 cm sec–1. Second, it was decelerated by northeast winds rather than by northwest winds in a frequency range of 0.3 and 0.4 cpd. Third, the scale analysis showed that the Tushima Current is approximately in geostrophic balance. The best empirical relationship between the measured Tushima Current and cross-channel adjusted sea level difference is given by
相似文献
279.
Computation of wave-making resistance of a catamaran in deep water using a potential-based panel method 总被引:1,自引:0,他引:1
This paper presents a potential-based boundary element method for solving a nonlinear free-surface flow problem for a Wigley catamaran moving with a uniform speed in deep water. Since the interior flow of each monohull of the catamaran is different from the exterior flow, both monohulls must be considered as lifting bodies. The pressure Kutta condition is imposed at the trailing-edge of the lifting body by determining the dipole distribution, which generates required circulation on the lifting part. The effects of wave interference and hull separation on the hydrodynamic characteristics of the catamaran hull are analyzed and the validity of the computer scheme is examined by comparing the wave resistance with the numerical results of others. The present method could be a useful design tool for screening the suitable combinations of hull parameters and hull spacing at the preliminary design stage of catamaran hull. 相似文献
280.
The annual net and gross primary production by phytoplankton in Akkeshi Bay Hokkaido, are estimated to be 146±25 g C m–2y–1 and 416±53 g C m–2y–1, respectively. The annual means of the net and gross efficiency between primary production and solar radiation are estimated to be 0.26 % and 0.79 %, respectively. 相似文献
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