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排序方式: 共有490条查询结果,搜索用时 36 毫秒
1.
Yoshio Kubo 《Celestial Mechanics and Dynamical Astronomy》1990,50(2):165-187
Hamiltonian mechanics is applied to the problem of the rotation of the elastic Earth. We first show the process for the formulation of the Hamiltonian for rotation of a deformable body and the derivation of the equations of motion from it. Then, based on a simple model of deformation, the solution is given for the period of Euler motion, UT1 and the nutation of the elastic Earth. In particular it is shown that the elasticity of the Earth acts on the nutation so as to decrease the Oppolzer terms of the nutation of the rigid Earth by about 30 per cent. The solution is in good agreement with results which have been obtained by other, different approaches. 相似文献
2.
The first year of sodium nightglow observations from Natal (6°S, 35°W) are examined. Time variations appear to follow a pattern of their own, different from low latitude results. The major seasonal peak occurs in September-October and the average variation during the night decreases from dusk to dawn. Statistics on cloud coverage show that Natal has roughly only about 3 clear hours per night. The best observing period is April with an average of 5 clear hours per night. 相似文献
3.
4.
Mercury emissions from the incineration of automobile shredder residues (ASRs) were investigated. Continuous monitoring of elemental and reactive gaseous Hg in flue gas was performed in lab-scale and plant-scale ASR incineration. Results of continuous monitoring agreed with those obtained using the JIS K0222 method and Ontario-Hydro method. Before cleaning by air pollutant control devices (APCDs), reactive Hg was the dominant form of that element in both lab-scale and plant-scale results. Emission factors of reactive Hg before APCDs estimated from monitoring results showed large differences between plant-scale and lab-scale emissions. The emission factor in the plant scale was more than 10 times larger than that in the lab-scale, which is explainable by the different Hg contents of ASR. Based on plant-scale monitoring at the stack, emission factors after APCDs were estimated as 0.79 mg-Hg/Mg-ASR for elemental Hg and 6.8 mg-Hg/Mg-ASR for reactive Hg. Using these emission factors, total Hg emissions from ASR incineration were estimated as 2.2 kg/a. An ASR incineration plant investigated in this study used highly effective APCDs. Consequently, these emission factors might result in underestimation of national Hg emissions from ASR incineration. Emission factors estimated from lab-scale monitoring at a fabric filter outlet side might be more appropriate. However, even if emission factors calculated from plant-scale or the lab-scale monitoring are used, estimated emissions are still less than 1.0% of total Hg emissions in Japan. Therefore, Hg emissions from ASR incineration can be evaluated as insignificant. Unless Hg contents of ASR increase extremely, ASR incineration would be a minor source of Hg atmospheric emission in Japan, even if all ASRs were incinerated. 相似文献
5.
Yuhei Yamamoto Yoshio Takahashi Yutaka Kanai Yoshio Watanabe Tomoya Uruga Hajime Tanida Yasuko Terada Hiroshi Shimizu 《Applied Geochemistry》2008,23(8):2452-2461
The uranium LIII-edge XANES spectra for natural rocks at the concentration range of 0.96–124 mg kg−1 were measured using a log spiral bent crystal Laue analyzer (BCLA) combined with a multi-element Ge detector. It was found that the quality of the XANES spectra using the BCLA was greatly improved due to a reduction of interfering fluorescence from major components such as Rb and Sr. The ratio of signal to background intensities in the U LIII-edge XANES spectra increased by a factor of 2.9–17 with the use of the BCLA, which greatly enhanced the detection limit for the speciation of the oxidation states of U or the U(IV)/U(VI) ratio of natural samples. In addition, it was demonstrated that the fluorescence XANES method coupled with the BCLA enable determination of the speciation of U for various natural samples such as acidic igneous rocks, ferromanganese nodules, sediments, and some sedimentary rocks such as shale and limestone. 相似文献
6.
Microbial manganese oxidation in seawater was carried out in enrichment cultures which were obtained from the seawater supply system at the Marine Science Museum, Tokai University (Shimizu-shi, Japan). The manganese oxide formed was well-crystallized todorokite. The major element composition was within the range of marine manganese concretions and the O/Mn molar ratio was 1.8. The conditions for formation of manganese oxide minerals in marine environments are discussed on the basis of these results. 相似文献
7.
Yoshio Takasugi Akira Hoshika Hideaki Noguchi Terumi Tanimoto 《Journal of Oceanography》1994,50(1):65-80
The strong tidal current (tidal jet) in straits generates tidal vortices with a scale of several kilometers. The role of the vortices in material transport was investigated in the Neko Seto Sea, located in the western part of the Seto Inland Sea of Japan. A clockwise vortex with a diameter of about 0.8 km was observed in Nigata Bay (lying between two straits, the Neko Seto Strait and the Meneko Seto Strait). It was concluded that the clockwise vortex was the tidal vortex which was generated by the tidal jet in the Meneko Seto Strait. The vortex moved into the bay with the tide, but tended to stay on the sand bank in the bay. It was confirmed by current measurement with an ADCP and turbidity measurement that the secondary convergent flow was generated in the bottom layer of the vortex. This secondary flow seemed to contribute to the formation of the sand bank. It was suggested that tidal vortices may play an important role in the sediment transport and formation of topography in and around straits. 相似文献
8.
Tetsuo Yanagi Satoru Takahashi Akira Hoshika Terumi Tanimoto 《Journal of Oceanography》1996,52(5):539-552
Seasonal variation in the transport of suspended matter across the East China Sea is investigated with the use of results of field observations and diagnostic numerical experiments. Suspended matter is transported from the shelf edge to the inner shelf in summer and from the inner shelf to the shelf edge in autumn and winter due to the vertical circulation mainly induced by the monsoon wind. The maximum transport of suspended matter from the inner shelf to the shelf edge occurs in autumn. 相似文献
9.
Yutaka W. Watanabe Yoshiyuki Takahashi Takashi Kitao Koh Harada 《Journal of Oceanography》1996,52(3):301-312
Concentrations of total carbonate, alkalinity and dissolved oxygen were obtained near the 1973 GEOSECS stations in the North Pacific subpolar region north of 40°N along 175°E between 1993 and 1994. A difference of excess CO2 content between the GEOSECS and our expeditions was estimated. The maximum difference in water column inventory of excess CO2 has increased by about 280 gC m–2 above 2000 m depth which apparently means an uptake of excess CO2 taken from air to sea during the last two decades. An averaged value of the annual flux of excess CO2 at 75–1000 m depth was 8.63±2.01 gC m–2yr–1 in the North Pacific subpolar region. By introducing the annual flux of excess CO2 into a two-box model for the North Pacific subpolar region, a penetration factor of excess CO2 from air to sea was obtained to be 1.08×10–2 gC m–3ppm–1 in the North Pacific subpolar region. Based on this factor, the surface concentration of excess CO2 in the North Pacific subpolar region was estimated to be 68 mole I–1, suggesting that the North Pacific subpolar region absorbed atmospheric excess CO2 more than the saturated concentration of excess CO2. Total amount of excess CO2 taken from the North Pacific subpolar region by 1993 was estimated to be 36.2×1015 gC, which was equal to about one tenth of that released by human activities after the preindustrial era. 相似文献
10.
Yusuke Okazaki Osamu Seki Takeshi Nakatsuka Tatsuhiko Sakamoto Minoru Ikehara Kozo Takahashi 《Journal of Oceanography》2006,62(5):639-648
Cycladophora davisiana, a radiolarian species dwelling at mesopelagic depths, is known as a representative glacial fauna due to its unique distribution
during glacial periods. In the present ocean, abundant production of C. davisiana is only observed in the Okhotsk Sea, indicating an adaptation of C. davisiana for seasonal sea-ice covered conditions. We found pronounced abundant production of C. davisiana during the early to middle Holocene in the Okhotsk Sea, suggesting more favorable conditions for C. davisiana than the present Okhotsk Sea. In order to clarify the reason, oceanographic conditions during the Holocene were reconstructed
based on biomarkers, lithogenic grains including ice-rafted debris (IRD), biogenic opal, and total organic carbon (TOC) in
two sediment cores from the Okhotsk Sea. These indicators suggest that the pronounced C. davisiana production may be attributed to: 1) a supply to mesopelagic depths under intensified stratification of fine organic particles
derived from coccolithophorids, bacteria, and detrital materials; and 2) cold, well-ventilated intermediate water formation. 相似文献