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481.
Summary The diurnal variations of water vapor in central Japan were investigated with GPS-derived precipitable water (PWV) and surface
meteorological data as classified to three kinds of locations. Twenty-five clear days in central Japan in August 2000 were
investigated to clarify the role of water vapor in the nocturnal maximum in the diurnal cycle of convective rainfall. The
diurnal variations of PWV and some meteorological factors were composite during the selected days at 6 stations. The PWV shows
a clear diurnal cycle with the amplitude of 3.4 mm to 8.8 mm and changes little during the period from the morning to noon.
The daily amplitude of PWV is the largest in basin and smallest in plain although mean of PWV keeps high value in plain. A
typical feature of the diurnal variation in central Japan is a maximum appearing in the evening. The time of maximum is from
1800 LST to 2000 LST, and minima appears at noon nearly in mountainous area and basin, while in early morning in plain. The
diurnal maximum of PWV appears earlier in mountainous region than in plain.
A diurnal cycle of specific humidity can be observed in all locations, and the amplitude in mountainous region is especially
large compared with that in basin and plain. It is important to notice that there are remarkable differences in specific humidity
among the six stations. The results suggest that the diurnal variation of PWV seems to be strongly affected by the local thermal
circulations generated by the topography around these stations. The moisture transport causes the differences in phase of
the diurnal cycle of PWV between different locations as well as the phase difference in precipitation. A very clear diurnal
variation in surface air temperature is similar to that of solar radiation, with a minimum in the morning and a maximum in
early afternoon. Maximum of surface wind speed are corresponded to peak of precipitation very well. It can be concluded that
the amplitude of solar radiation increases with altitude as opposed to the situation of PWV generally.
The precipitation observed frequently in the evening also shows a similar diurnal variation to that of the PWV, indicating
the peak of precipitation appearing in late afternoon or in the evening over central Japan. Meanwhile the PWV reaches its
nocturnal maximum. There is a good relationship between the diurnal cycle of observed precipitation and that of the PWV.
Authors’ addressess: Guoping Li, Department of Atmospheric Sciences, Chengdu University of Information Technology, #3 Section
3, Ren Min Nan Road, Chengdu, Sichuan 610041, P.R. China; Dingfa Huang, Department of Surveying Engineering, Southwest Jiaotong
University, Chengdu, China; Fujio Kimura, Tomonori Sato, Institute of Geoscience, University of Tsukuba, Tsukuba, Japan. 相似文献
482.
Agawa gold prospect, located in Yamaguchi Prefecture, southwestern Japan, is a small prospect, where placer gold has been explored and mined since the 17th century. We investigated the prospect to clarify the genesis of the deposit based on the geology, hydrothermal alteration, geochronology, and ore mineralogy. The main mineralized zone of the prospect has a horizontal and vertical extensions of 500 m and 100 m, respectively, and a width of less than 100 m. Gold mineralization in the prospect occurs as dissemination and stockwork veinlets in the intensely sericitized rocks at the apical part of the Agawa dioritic porphyry intrusion at 86.5–88.5 Ma. Mineralization is typified by at least three stages – an early stage characterized by the occurrence of pyrrhotite and native gold; a middle stage by chalcopyrite; and a late stage by pyrite–bornite. Mineral assemblage and fluid inclusion microthermometry estimation suggest a trend of decreasing temperatures from 400°C to 160°C at a constant sulfur fugacity. The mineralizing fluids formed by the mixing of a hypogene fluid of possibly magmatic origin with an external lower‐temperature and lower‐salinity fluid. The mixing process decreased the temperature and salinity of the fluid, resulting in the precipitation of sulfides, native gold and Bi–Te alloys and sulfosalts. The magnetite‐series signature of the Agawa porphyry and related molybdenite‐bearing mineralization indicate that the plutonism of the San‐in granitoids belt extends to the westernmost end of the Honshu Island. The compiled geochronology and distribution of the metallic deposits in the southwestern Japan arc show that transition from ilmenite‐series to magnetite‐series plutonism started earlier in the west, and shifted eastwards with time during the period from Late Cretaceous to Paleogene. 相似文献
483.
Manganese oxides precipitated from aerated well sea water at the Marine Science Museum, Tokai University, have been analyzed chemically and mineralogically. The ratios are lower in todorokite than in birnessite but these minerals have similar contents of minor transition metals, which can be taken up additionally from sea water after the precipitation of Mn oxides. On the basis of these results, the genesis of Mn minerals is discussed in relation to marine Mn nodules. 相似文献
484.
Viscoelastic (VE) dampers are sensitive to temperature, excitation frequency, and strain level. As they dissipate the kinetic energy from earthquake or wind-induced structural vibrations, their temperature increases from the heat generated, consequently softening their VE materials and lowering their dynamic mechanical properties. Temperature increase can be significant for long-duration loading, but can be limited by heat conduction and convection which depend on damper configuration. The writers analytically explored such effect on the six different dampers by using their previously proposed three-dimensional finite-element analysis method. Results provided better understanding of how heat is generated within the VE material, conducted and stored in different damper parts, and dispersed to the surrounding air. These results also led to characterization of both local (e.g., temperatures, properties, and strain energy density) and global (e.g., hysteresis loops, and stiffness) behavior of VE dampers, and provided a framework for a new simplified one-dimensional (1D) modeling approach for time-history analysis. This new proposed 1D method greatly improves the computation time of the previously proposed long-duration method coupling fractional time-derivatives VE constitutive rule with 1D heat transfer analysis. Unlike the previous method, it idealizes uniform shear strain and VE material property distributions for computational efficiency, but still simulating non-uniform temperature distribution along the thickness direction of the VE material. Despite the approximations, it accurately predicts VE damper global responses. 相似文献