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61.
Yukiyoshi Iwata Tomoyoshi Hirota Masaki Hayashi Shinji Suzuki Shuichi Hasegawa 《水文研究》2010,24(13):1755-1765
Despite the potential impact of winter soil water movements in cold regions, relatively few field studies have investigated cold‐season hydrological processes that occur before spring‐onset of snowmelt infiltration. The contribution of soil water fluxes in winter to the annual water balance was evaluated over 5 years of field observations at an agricultural field in Tokachi, Hokkaido, Japan. In two of the winters, soil frost reached a maximum depth of 0·2 m (‘frozen’ winters), whereas soil frost was mostly absent during the remaining three winters (‘unfrozen’ winters). Significant infiltration of winter snowmelt water, to a depth exceeding 1·0 m, occurred during both frozen and unfrozen winters. Such infiltration ranged between 126 and 255 mm, representing 28–51% of total annual soil water fluxes. During frozen winters, a substantial quantity of water (ca 40 mm) was drawn from deeper layers into the 0–0·2 m topsoil layer when this froze. Under such conditions, the progression and regression of the freezing front, regulated by the thickness of snow cover, controlled the quantity of soil water flux below the frozen layer. During unfrozen winters, 13–62 mm of water infiltrated to a depth of 0·2 m, before the spring snowmelt. These results indicate the importance of correctly evaluating winter soil water movement in cold regions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
62.
Hidekazu Yoshida Koshi Yamamoto Yuki Murakami Nagayoshi Katsuta Toru Hayashi Takeshi Naganuma 《Environmental Geology》2008,55(6):1363-1374
Takashikozo is a phenomenon of Quaternary sediments in Japan. They are cylindrical Fe-oxyhydroxide nodules that form as plaques round
plant roots, where Fe is preferentially concentrated to develop a solid wall. Structural features suggest that after the roots
have decayed, the central space where the roots were situated acts as a flow path for oxidized water. Analysis of microbial
16S rDNA extracted from the nodules identified iron-oxidizing bacteria encrusted round the roots where they are the likely
initiators of nodule formation. Direct microscopic observation revealed an accumulation of Fe-oxyhydroxides that fill the
pore spaces and is also likely to be linked with the encrusting microbial colonies. Geological history and nanofossil evidence
suggest that these Fe-nodules may have been buried at a depth of up to several tens of meters for at least 105 years in reducing Quaternary sediments. Thus Fe-oxyhydroxide nodules that have formed in a geological environment at the
interfaces between water and rock by microbial mediation can persist under reducing conditions. If this is the case, the phenomenon
is significant as an analogue of post-closure conditions in radioactive waste repositories, since it could influence nuclide
migration. 相似文献
63.
Saeko S. Hayashi 《Astrophysics and Space Science》1995,224(1-2):479-480
Diffraction-limited imaging in the near-IR (with the aid of adaptive optics) to middle-IR wavelengths will be a major breakthrough with 8m IR-optical telescopes. Special interest is on the scale of planet formation, that is, within 100 AU of the embedded sources in the nearby Taurus or Ophiuchus clouds. In this report, we demonstrate the sensitivity of a telescope with a virtual instrument that covers a wide spectral range. 相似文献
64.
Summary Stress concentration at the bottom of a borehole due to the corners with small radius of curvature in an axial section and
its effect on the azimuth of breakout was studied. To this end, a 3-D finite element analysis was conducted and the stress
around the borehole was examined for boreholes arbitrarily oriented to three principal axes of remote stress. Results show
that, in the case of high strength rock, compressive failure resulting in spalling of a borehole may occur only at the bottom
of the borehole. The spalling can occur continuously with drilling, and results in continuous spalling with depth, i.e., a
breakout. This type of breakout tends to form on one side of the borehole and its orientation is approximately perpendicular
to the orientation of standard breakouts, inferred from the stress concentration due to the cylindrical shape of the borehole. 相似文献
65.
Kohiyama Masayuki Yamashita Norihiko Sato Tadanobu Hengjian Lu Maki Norio Tanaka Satoshi Hayashi Haruo 《Natural Hazards》2003,29(3):501-522
The Nishinomiya Built Environment Database, which can be used to analyze the disaster process of the 1995 Hanshin-Awaji Earthquake Disaster in Nishinomiya City, has been expanded with new data entries. The database contains the following very detailed datasets: (1) the urbanization area base map, (2) casualty data, (3) three sets of building damage data surveyed by the Nishinomiya City, the Architectural Institute of Japan and the City Planning Institute of Japan, and the Kobe University, (4) building property data based on the real estate tax roll, (5) photographs of the damaged buildings with the information on the place and orientation of the picture, and (6) the estimated distribution of the seismic ground motion. The seismic ground motion was simulated for the southern part of Nishinomiya City and two verification sites in Kobe City and Amagasaki City. In the simulation, the borehole data of public facilities were used to model the surface soils as one-dimensional layers, taking into consideration the fact that the spatial distribution of the sediment/basement interface forms a slope. The model of the fault rupture process simulated the characteristics of the seismic motion at basement level, and amplification effects of the surface layers were evaluated based on multiple reflection theory. The distribution of peak ground acceleration and peak ground velocity was estimated from acceleration response spectra at each borehole point. In addition, the relationship between simulated seismic ground motion and building damage was studied based on newly proposed band-passed spectrum intensity using the expanded database. This confirmed that detailed categorization is necessary in order to evaluate the fragility functions, especially for reinforced concrete structures. The database should provide fundamental information for identifying the relationship between the ground motions and the extent and pattern of building damage, or the pattern of the occurrence of casualties.Presently 相似文献
66.
We present high resolution CS and CO maps of Cep A region made with the 45m telescope at Nobeyama. The CS map shows that a dense cloud surrounding the proto-star cluster extends in the North-South direction and is probably rotating. The bipolar molecular flow apparent in the CO maps is well-collimated along East-West direction within 0.2 pc from the proto-stars. The dense cloud is gravitationally unstable and appears to be in a contracting phase to form a cluster of massive stars.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.NRO, a branch of the Tokyo Astronomical Observatory, University of Tokyo, is a cosmic radio observing facility open for outside users. 相似文献
67.
On the basis of the two-dimensional theory of elasticity, the theoretical analysis of a vertical, fluid-filled crack intersecting and oblique joint has been made for the extraction of geothermal heat from hot, dry rock masses, where the opening of the joint near a point of intersection and the frictional resistance against slips along the joint are taken into account. The stress intensity factors are evaluated for discussing crack kinking at the upper joint tip, and the sufficient conditions on theinclination of the joint and on the length between the upper joint tip and the point of intersection are obtained for keeping a fluid-filled crack stable just beneath a joint. It is also shown that the volume of the stable reservoir created by using a joint is much larger than that of a fluidfilled crack in a jointless rock mass, even if the joint is oblique and is opened up by the fluid pressure. 相似文献
68.
The biomass and production rate of net zooplankton were studied at eight stations in Yatsushiro Bay, Japan, monthly from May
2002 to April 2003. Based on environmental conditions, the bay was divided into three regions, viz. northern (average depth,
salinity and chlorophyll a concentration: 11 m, 31.8 and 6.5 μg l−1, respectively), central (30 m, 32.8 and 3.2 μg l−1, respectively) and southern (43 m, 33.4 and 1.9 μg l−1, respectively). Net zooplankton biomass was high in warm months and low in cold ones, with annual averages of 20.2, 38.8
and 16.4 mg C m−3 in the northern, central and southern regions, respectively. Copepods were the most important constituent (>ca. 70% of net
zooplankton biomass) in all regions. The northern region was characterized by the dominance of Oithona spp. in summer and Acartia spp. in winter-spring. In the central region, Microsetella norvegica was most pronounced in summer-fall. In both central and southern regions, Calanus sinicus and Eucalanus spp. dominated in winter-spring and fall, respectively. The annual average net zooplankton secondary production rate was
4.4, 7.5 and 3.9 mg C m−3d−1 in the northern, central and southern region, respectively. Combining the results from the present study with those from
other collaborative works on microzooplankton allowed us to determine the trophic interactions in Yatsushiro Bay. If the secondary
producers depend entirely on phytoplankton for food, their daily carbon requirement is equivalent to 12.5, 21.6 and 19.1%
of the phytoplankton biomass in the respective regions. 相似文献
69.
Qiuming Pei Shouting Zhang Ken‐ichiro Hayashi Liang Wang Huawen Cao Yu Zhao Xinkai Hu Kairui Song Weiwei Chao 《Resource Geology》2019,69(2):148-166
The recently discovered Xiaobeigou fluorite deposit is situated in the southern part of the Southern Great Xing'an Range metallogenic belt. Fluorite‐bearing veins are rather common over the whole area. So far, 11 mineralized veins have been delineated at the Xiaobeigou deposit. Orebodies of the deposit are mainly hosted in Permian and Jurassic volcano‐sedimentary rocks. The orebodies in this mining district exhibit a well‐developed vertical zonation: from top to bottom, the orebodies can be divided into upper, central, and lower zones. The central zone is the most important part for mining operations, and it shows lateral zonation of fluorite mineralization. Rare earth element (REE) contents of the investigated samples are relatively low (less than 30.2 ppm). Furthermore, the REE contents of the fluorite grains from early to late ore stages exhibit a decreasing trend. All the fluorite samples show no or slightly positive Eu anomalies. Three types of fluid inclusions (FIs) are distinguished in the quartz and fluorite samples, including pure‐liquid single‐phase (PL‐type), liquid‐rich two‐phase (L‐Type), and vapor‐rich two‐phase (V‐type) FIs. The FIs hosted in early‐stage quartz were homogenized at 159.5–260.7°C (mainly 160–240°C); their salinities range from 0.18 to 1.22 wt.% NaCl eqv. The FIs hosted in early‐stage fluorite yield slightly lower homogenization temperatures of 144.4–266.8°C (peaking at 140–220°C), which correspond to salinities of 0.18–0.88 wt.% NaCl eqv. Homogenization temperatures and salinities for the late stage are 132.5–245.8°C (mainly 160–180°C) and 0.18–1.40 wt.% NaCl eqv., respectively. Laser Raman spectroscopy of FIs shows that both the vapor and liquid compositions of the inclusions are dominated by H2O. The H–O isotopic compositions at Xiaobeigou suggest that the ore‐forming fluids are predominantly of meteoric water origin. The Xiaobeigou deposit can be classified as a typical low‐temperature hydrothermal vein‐type fluorite deposit. Combined with regional data, we infer that the fluorite mineralization occurred during the Late Mesozoic in an extensional setting. 相似文献
70.
Asten Michael W. Yong Alan Foti Sebastiano Hayashi Koichi Martin Antony J. Stephenson William J. Cassidy John F. Coleman Jacie Nigbor Robert Castellaro Silvia Chimoto Kosuke Cornou Cécile Cho Ikuo Hayashida Takumi Hobiger Manuel Kuo Chun-Hsiang Macau Albert Mercerat E. Diego Molnar Sheri Pananont Passakorn Pilz Marco Poovarodom Nakhorn Sáez Esteban Wathelet Marc Yamanaka Hiroaki Yokoi Toshiaki Zhao Don 《Journal of Seismology》2022,26(4):757-780
Journal of Seismology - Site response is a critical consideration when assessing earthquake hazards. Site characterization is key to understanding site effects as influenced by seismic site... 相似文献