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101.
We measured the electrical resistivity of face-centered-cubic (fcc) structured iron hydrides at high pressures up to 65 GPa and high temperatures in a laser-heated diamond anvil cell. The results indicate that the resistivity of stoichiometric fcc FeHx (x ~ 1.0) is smaller than that of fcc Fe at the same pressure and temperature conditions. The same behavior was also observed in fcc FeNiHx (x ~ 1.0). On the other hand, hydrogen-poor fcc FeHx (x < 0.77) showed a resistivity comparable to that of the fcc phase of pure iron. Therefore, we conclude that the stoichiometric fcc Fe (–Ni) hydride is more conductive than Fe (–Ni) with the same crystal symmetry, and the impurity resistivity of hydrogen in Fe is vanishingly small. Even if hydrogen is the major light element in the Earth's core, it would have little influence on the electrical and thermal conductivity of Fe–Ni alloys, and hence the thermal evolution of the core. 相似文献
102.
Bao‐Lin Xue Zhanling Li Xin‐An Yin Tieliang Zhang Shin'ichi Iida Kyoichi Otsuki Takeshi Ohta Qinghua Guo 《水文研究》2015,29(6):1017-1026
A larch forest in eastern Siberia was characterized by the presence of two distinct storeys, the overstorey with a small leaf area index (LAI) and a dense understorey with a relatively large LAI. To understand the roles of the overstorey and understorey in forest–atmosphere water exchange, canopy conductance (Gc), a critical parameter used in determining the energy and mass exchange, was calculated on the basis of latent heat flux above the overstorey and understorey, measured separately. Results showed that Gc for the overstorey (Gco) and understorey (Gcu) experienced different seasonal fluctuations. Gco was smaller than Gcu during periods of leaf expansion and leaf fall and showed an increasing trend until 1 month after the onset of leaf expansion. In contrast, a sharp decrease in Gco was observed immediately before onset of leaf fall. Furthermore, Gco was slightly larger than Gcu during the fully foliated period. A simple model using solar radiation and vapour pressure deficit (D) as inputs successfully reproduced the Gc in fully foliated periods with acceptable accuracy. Furthermore, both the understorey and overstorey in this study have a large reference Gc (Gc at D = 1 KPa) than their counterparts of other boreal forests and would not be able to sustain a constant leaf–soil water potential difference as D increases. We speculated that this confers the forest with an advantage allowing it to be able to sustain carbon assimilation during large D days and thus provides for the survival of the ecosystem during the short growing season at this site. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
103.
Daisuke Inazu Tadahiro Sato Satoshi Miura Yusaku Ohta Kazuyuki Nakamura Hiromi Fujimoto Christopher F. Larsen Tomoyuki Higuchi 《Journal of Oceanography》2009,65(3):335-347
An accurate prediction of ocean tides in southeast Alaska is developed using a regional, barotropic ocean model with a finite
difference scheme. The model skill is verified by the observational tidal harmonics in southeast Alaska including Glacier
Bay. The result is particularly improved in Glacier Bay compared to the previous model described by Foreman et al. (2000). The model bathymetry dominates the model skill. We re-estimate tidal energy dissipation in the Alaska Panhandle
and suggest a value for tidal energy dissipation of 3.4 GW associated with the M2 constituent which is 1.5 times the estimation of Foreman et al. (2000). A large portion of the M2 energy budget entering through Chatham Strait is dissipated in the vicinity of Glacier Bay. Moreover, it is shown that the
developed model has the potential to correct the ocean tide loading effect in geodetic data more efficiently than the model
of Foreman et al. (2000), especially around Glacier Bay. 相似文献
104.
Michinori Honda Shintaro Ohno Atsushi Iizuka Katsuyuki Kawai Hideki Ohta 《Geotechnical and Geological Engineering》2011,29(2):171-180
An evaluation method for the mechanical behavior of unsaturated soils is studied in this paper. Although the mechanical behavior
of unsaturated soils is complicated, a simple modeling is preferable in practice. This is because the soil properties are
not homogeneous and ground data is limited when structures are being designed. In addition, in order to evaluate the reliability
of the design, the physical meanings of the parameters applied in the prediction model should be clear. Firstly, the authors
study the relationship between compaction curves and compression indexes in the unsaturated state that is used in the proposed
constitutive model. Based on the constitutive model, the stress paths for constant volume shear tests are formulated under
a constant void ratio condition and the stress paths for undrained shear tests are calculated under a constant water content
condition. In the case of unsaturated specimens, the volume of these specimens changes with the shear deformation and the
stress paths depend on the initial degree of saturation. The results of the calculation qualitatively describe the test results
by considering the changes in effective confining pressure in the undrained condition and the water retention curves. 相似文献
105.
Diamond-bearing carbonate rocks from Kumdy-Kol, Kokchetav massif, Kazakhstan, were strongly altered by fluids flowing through fractures and infiltrating along grain boundaries during exhumation. Alteration includes retrogradation of high-grade silicate assemblages by hydrous minerals, replacement of diamond by graphite and of dolomite by calcite. Diamond-bearing carbonate rocks are among the most intensely altered isotopically with δ18OVSMOW values as low as +9‰, δ13CVPDB=−9‰, and 87Sr/86Sr as high as 0.8050. Evidence of isotopic equilibration between coexisting dolomite and high-Mg calcite during ultrahigh-pressure metamorphism (UHPM) is preserved only rarely in samples isolated from infiltrating fluids by distance from fractures. Isotopic heterogeneity and isotopic disequilibrium are widespread on a hand-specimen scale. Because of this lack of homogeneity, bulk analyses cannot provide definitive measurements of 13C/12C fractionation between coexisting diamond and carbonate. Our study adequately documents alteration on a scale commensurate with observed vein structures. But, testing the hypothesis of metamorphic origin of microdiamonds has not fully succeeded because our analytical spatial resolution, limited to 0.5 mm, is not small enough to measure individual dolomite inclusions or individual diamond crystals. 相似文献
106.
Yasunori Mahara Tomoko Ohta Tomochika Tokunaga Hiroyuki Matsuzaki Eiji Nakata Yuki Miyamoto Yukihiro Mizuochi Toshiharu Tashiro Masahiro Ono Toshifumi Igarashi Keisuke Nagao 《Applied Geochemistry》2012
Fifty-three samples, including brines associated with oil and natural gas reservoirs and groundwater samples from deep boreholes, were collected from the Pacific and Japan Sea coastal regions in Japan. The 129I/127I and 36Cl/Cl ratios, and stable isotopes (δD and δ18O) are compared to investigate differences related to the geotectonic settings of the two regions. The δD and δ18O data indicate that brine and groundwater from the Pacific coastal region reflect mixing of meteoric water with connate seawater in the pores of sedimentary rocks. On the other hand, brine and groundwater from the Japan Sea coastal region have been hydrothermally altered. In particular, brines associated with petroleum accumulations at Niigata and Akita showed the same isotopic characteristics as fluids found in the Kuroko deposits of the Green Tuff region in northeastern Japan. There is little difference in the 36Cl/Cl ratios in brine and groundwater from the Pacific and Japan Sea coasts. Most brine and some deep groundwater, except those from the Pleistocene Kazusa Group, have already reached the average secular equilibrium ratio of 9.9 ± 2.7 × 10−15 for their mudstone and sandstone reservoirs. There was no correlation between the 36Cl/Cl ratios and differences in geotectonic setting between the Pacific and the Japan Sea coast. The molar I/Br ratio suggests that the I in all of water samples was of biogenic origin. The average 129I/127I ratio was 290 ± 130 × 10−15 to 294 ± 105 × 10−15 in both regions, showing no relationship to the different geotectonic settings. The uncontaminated brine and groundwater samples are likely to have retained the original 129I/127I ratios of marine I released from the old organic matter stored in sedimentary rock. 相似文献
107.
K. Ohta S. Takano S. Kagaya H. Yamada H. Minakami 《International journal of geographical information science》2013,27(6):687-698
To improve the geographical accessibility of neurosurgical emergency hospitals for elderly people, we developed several alternative site plans for a new neurosurgical emergency hospital in Sapporo, Japan. Hospitals, population data, routes, and the numerical information for the Analytic Hierarchy Process computations were input into a Geographical Information System. Pairwise comparison revealed the following weights which were assigned to each of the four criteria: 0.674 for availability of hospital beds; 0.169 for the maximum road distance of the shortest routes; 0.101 for the elderly population within a 3‐km radius; and 0.056 for the median road distance of the shortest routes. The alternative proposed could cover 4000 more elderly people in the 3‐km radius of the hospitals. The integration of Geographical Information Systems and the Analytic Hierarchy Process constitutes a powerful tool for analysing traffic conditions in mid‐sized cities and for suggesting city planning to improve prognosis of stroke. 相似文献
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