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21.
Junichi Sakai Shigeki Unjoh 《地震工程与工程振动(英文版)》2006,5(1):103-110
1 Introduction Since the 1971 San Fernando earthquake, a signi?cant amount of research has been conducted on the ductility capacity of reinforced concrete bridge columns, resulting in signi?cant advances in the seismic design of bridges. Since most tests have been done in static or quasistatic conditions and unidirectional loading conditions, however, no method that properly evaluates the effect of multidirectional dynamic loading has been developed, and design recommendations on this effect a… 相似文献
22.
The apparent stability constants for chloride and sulfate ions with Co (II) at ionic strength of 0.67 were determined by the cation exchange method. The value of the stability constant
1 for chloride ion with Co (II) ion was 0.79±0.055. The stability constants
1,
2 and 3 for sulfate ion with Co (II) ion were 12.0±0.27, 91.5±11.4 and l,110±250, respectively. The chemical species of Co (II) in seawater was estimated at the pH of 8.0 to be present as Co2+ (63%), CoCl+ (27%) and CoSO4
0 (8.6%) using the known value of dissociation constant of Co (II), and under the assumption that only major inorganic anions are responsible for the chemical equilibrium of Co (II). 相似文献
23.
Shigeki?HosodaEmail author Shang-Ping?Xie Kensuke?Takeuchi Masami?Nonaka 《Journal of Oceanography》2004,60(5):865-877
The North Pacific Central Mode Water (CMW) is a water mass that forms in the Kuroshio-Oyashio Extension (KOE) region with
characteristic low potential vorticity. Recent studies have suggested that the CMW, as low potential vorticity water, plays
an important role in the adjustment of the subtropical gyre and subsurface variability on decadal to interdecadal timescales.
We have forced a realistic ocean general circulation model (OGCM) with observed wind stress and sea surface temperature (SST)
forcing to investigate the decadal variations of the CMW. Associated with the large atmospheric changes after the mid-1970s
climate regime shift, the upper thermocline experiences a cooling as negative SST anomalies in the central North Pacific are
subducted and advected southward. In addition to this thermodynamic response, the CMW’s path shifts anomalously eastward in
response to anomalous Ekman pumping. This eastward shift of the core of the CMW produces a lowering of the isotherms, and
a consequent warming, on the path of the CMW core. This warming partially counteracts the cooling associated with subducted
surface anomalies, and it may be responsible for the reduced temperature variations at the climatological position of the
CMW when both anomalous wind and heat fluxes are given. Lateral induction across the sloping bottom of the winter mixed layer
in the KOE is critical to the formation of the low potential vorticity CMW. Coarse resolution models, which are widely used
in climate modeling, underestimate the horizontal gradient of the mixed layer depth and form only a weak CMW or none at all.
We have conducted a coarse resolution experiment with the same OGCM, showing that the subsurface response is much reduced.
In particular, there is no dynamic warming in the CMW and the thermodynamic response to the SST cooling dominates. The resultant
total response differs substantially from that in the finer resolution run where a strong CMW forms. This sensitivity to the
model resolution corroborates the important dynamical role that the CMW may play with its distinctive low potential vorticity
character and calls for its improved simulation. 相似文献
24.
Kazuo Konagai Shigeki Takatsu Tetsuo Kanai Tomohiro Fujita Takaaki Ikeda Jörgen Johansson 《Soil Dynamics and Earthquake Engineering》2009
Earthquakes in active-folding zones often trigger long-lasting landform changes. Since an underground structure closely follows the motion of its surrounding soils and rocks even after it was damaged in an intense earthquake, experts in charge of reconstruction have to wait until they are convinced that the soils and rocks have been stabilized. Kizawa tunnel was seriously cracked during the 23 October 2004 Mid-Niigata Earthquake. The upper half of the tunnel's cross-section near the north mouth shifted about 0.5 m sideways. Since a ring-shaped cross-section of a tunnel sustains the surrounding soil pressure, this crack pattern seemed to be serious. The authors collaborated with the Nagaoka Regional Development Bureau, Niigata Prefectural Government, in investigating the causes of the damage and in conducting long-term observation of the soils and rocks. This paper summarizes some findings for rational rehabilitations through the investigations. 相似文献
25.
Ken Arai Shigeki Wada Koichi Shimotori Yuko Omori Takeo Hama 《Journal of Oceanography》2018,74(1):39-52
Dynamics of fluorescent dissolved organic matter (FDOM) in ocean environments has received attention over the past few decades. Although it has appeared that in situ production of oceanic FDOM is mainly due to bacteria, the production and bio- and photodegradation processes of bacterial FDOM have not been elucidated. In this study, a culture experiment with bacteria was carried out to assess the production and biodegradation processes of bacterial FDOM. Photodegradation of bacterial FDOM and dissolved organic carbon (DOC) was also examined by exposure to a solar simulator. Bacterial FDOM consists of six components which were determined by parallel factor analysis (PARAFAC). Fluorescence intensities of protein-like FDOM increased with the bacterial biomass, but the increases of humic-like FDOM lagged behind the protein-like FDOM by 5–10 days. Exposure to simulated sunlight caused significant decreases in fluorescence intensities of all components; 52–94% of the initial intensities were lost during 24 h. While, the DOC concentration exhibited a small decrease through the experiment (1.9–11.1%). These results showed that photodegradability of bacteria derived DOC was much less than the fluorescence, indicating that the lifetime of bacteria-derived DOC is much longer than the length estimated by the fluorescence. The role of photobleached FDOM derived from bacteria may be significant in the biogeochemical cycle at the surface layer. 相似文献
26.
Malarvannan G Takahashi S Ikemoto T Isobe T Kunisue T Sudaryanto A Miyagi T Nakamura M Yasumura S Tanabe S 《Marine pollution bulletin》2011,63(5-12):541-547
Two species of fishes (n=52; tilapia and mullet) from industrialized and urbanized areas of Okinawa Island (Manko-Noha river, Hija river and Shikaza river) and from a remote area of Ishigaki Island (Anparu mudflat), Japan were collected between August 2005 and July 2006, and analyzed for five organochlorine compounds (OCs), viz., DDTs, PCBs, CHLs, HCHs and HCB. Concentrations and the contamination patterns of OCs in fishes varied between locations. Considerable residue levels of OCs, especially CHLs and DDTs were found in both fishes from the main Okinawa Island. These levels were relatively higher than the reported values for seafood from Japanese coasts, indicating that even now pollution sources of these contaminants still exist in this region. On the other hand, lower concentrations of OCs were detected in fishes from Ishigaki Island waters than those of other Japanese coastal waters, suggesting that this region is less contaminated by OC contaminants. 相似文献
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28.
In this paper, we propose a numerical simulation procedure of moored ship motions due to initial attack of large-scaled tsunamis and investigate the effects on the motions and mooring loads. The effect of methodology on selection of tsunami wave components and of the drag forces are then considered by using the numerical simulation method, applying to several case studies for LNG-carrier. Large ship motions and excessive mooring loads beyond the safe working loads are induced by the resonant tsunami wave components in the sway and surge motions and drag forces. 相似文献
29.
Journal of Oceanography - The authors examine small-scale spatiotemporal variability of the layer nearly 2000-m depth, which is the “bottom” of the present Argo observation system,... 相似文献
30.
Kurosegawa Terrane in Southwest Japan: Disrupted Remnants of a Gondwana-Derived Terrane 总被引：1，自引：0，他引：1
The Kurosegawa Terrane is an anomalous, disrupted, Paleozoic and Mesozoic lithotectonic assemblage characterized by fragments of continent and continental margins. It is located in Southwest Japan where it lies between two Mesozoic subduction complex terranes. The Kurosegawa Terrane is an exotic and far-travelled geologic entity with respect to its present position. Limestones of the Kurosegawa Terrane formed along a continental margin yield fusulinacean fossils Cancellina, Colania and Lepidolina. Accordingly, the Kurosegawa Terrane was once situated within the Colania-Lepidolina territory in the East Tethys-Panthalassa region at a palaeo-equatorial latitude, possibly close to the eastern margin of the South China and/or Indochina-East Malaya continental blocks. These blocks had rifted from Gondwana by late Devonian. They drifted northwards, passing through the Colania-Lepidolina territory in mid-Permian time, and amalgamated with the proto-Asian continent during the late Triassic. Subsequently, during the Cretaceous, parts of the allochthonous continental blocks and their associated tectonic collage were transpressed, dispersed, and displaced from the southeastern periphery of Asia towards the north. As a result, the Kurosegawa Terrane is formed as a disrupted allochthonous terrane, characterized by a serpentinite melange zone, lying between the adjoining Mesozoic subduction complex terranes. 相似文献