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51.
K. Kobayashi S. Tsuneta T. Tamura K. Kumagai Y. Katsukawa M. Kubo Y. Sakamoto N. Kohara T. Yamagami Y. Saito K. Mori 《Solar physics》2008,250(2):431-441
Spectroscopic observation of solar flares in the hard X-ray energy range, particularly the 20 ∼ 100 keV region, is an invaluable
tool for investigating the flare mechanism. This paper describes the design and performance of a balloon-borne hard X-ray
spectrometer using CdTe detectors developed for solar flare observation. The instrument is a small balloon payload (gondola
weight 70 kg) with sixteen 10×10×0.5 mm CdTe detectors, designed for a 1-day flight at 41 km altitude. It observes in an energy
range of 20−120 keV and has an energy resolution of 3 keV at 60 keV. The second flight on 24 May 2002 succeeded in observing
a class M1.1 flare. 相似文献
52.
Various types of endocrine disruptors or environmental hormones flow from their sources down into harbours through rivers and other watercourses, and are accumulated in sediment on the sea bottom. Tributyltin, which has been used as paint for ship bottoms, is considered one of the endocrine disruptors.In close cooperation with the other ministries and agencies, the Ports and Harbours Bureau of the Ministry of Land, Infrastructure and Transport carried out an investigation in 1999 to determine the actual condition of 12 endocrine disruptors in the sediment of 39 harbours, in order to gather fundamental data to be used in future examinations of policy. Furthermore, in 2000 the bureau chose seven harbours out of the above 39 harbours as subjects of an additional investigation regarding the surface distribution of endocrine disruptors in the harbour areas and the synchronistic change of accumulation of dioxin and other substances. As the result of the investigation regarding the surface distribution of endocrine disruptors accumulated in seven harbours, relatively high concentrations were measured in the innermost parts of harbours and the mouths of rivers. Synchronistic changes in the amount of dioxin and other substances accumulated in sediments of five harbours were determined. Small amounts of dioxin and other substances, including an especially small amount of coplanar-PCBs, were found in the layers formed before or around 1950. Relatively large amounts of these substances were measured in the upper layers formed during roughly 1960-1990, though no significant yearly differences in concentration could be identified. This result coincides with the facts that, during roughly 1960-1980, PCP and CNP were used as agricultural chemicals and full-scale production of PCBs started in 1960. 相似文献
53.
We report systematic noble gas variation within a regional scale in an area that is well separated from all hotspots surrounding a remarkable ridge-ridge-ridge type triple junction—the Rodriguez Triple Junction of the Indian Ocean. We applied a newly established technique to select basaltic glass samples from the Mid-Oceanic Ridge Basalt (MORB) suite from the studied area. Samples were selected to create regular spacing along the ridge axis for investigating the magma system beneath the ridge axis. All samples show a typical isotope signature as MORB regardless of moderate contributions of an atmospheric component. Remarkably, uniform isotope ratios were found even for Ne and Ar in each segment. Such ratios had not been recognized in any magmatic system in Mid-Oceanic Ridges. Elemental abundances of samples are controlled both by mixing with the atmospheric component and by degassing. Contribution of atmospheric components is controlled strongly by a high temperature reaction caused by equilibration of dissolved noble gases between magma and seawater. Of the three models of the magma system around the Rodriguez Triple Junction, controlled contamination without mechanical mixing in a magma chamber presents the most likely scenario. 相似文献
54.
Organized structures in developing turbulent flow within and above a plant canopy,using a Large Eddy Simulation 总被引:10,自引:9,他引:1
A Large Eddy Simulation (LES) model representing the air flow within and above a plant canopy layer has been completed. Using this model, the organized structures of turbulent flow in the early developmental stages of a crop are simulated and discussed in detail.The effect of the drag due to vegetation is expressed by a term added to the three-dimensional Navier-Stokes equation averaged over the grid scale. For the formulation of sub-grid turbulence processes, the equations for the time-dependent SGS (Sub-Grid-Scale) turbulence energy equation is used, which includes the effects of dissipation (both by viscosity and leaf drag), shear production and diffusion.The organized structure of turbulent flow at the air-plant interface, obtained numerically by the model, yields its contribution to momentum transfer. The three-dimensional large eddy structures, which are composed of spanwise vortices (rolls) and streamwise vortices (ribs), are simulated near the air-plant interface. They are induced by the shear instability at inflection points of the velocity profile. The structure clearly has a life cycle. The instantaneous image of the structure is similar to those observed in the field observations of Gaoet al. (1989) and in the laboratory flume experiments of Ikeda and Ota (1992). These organized structures also account for the well known fact that the sweep motion of turbulence dominates momentum transport within and just above a plant canopy, and the motion of ejection prevails in the higher regions. 相似文献
55.
56.
Phytoplankton community reorganization driven by eutrophication and warming in Lake Biwa 总被引:1,自引:0,他引:1
Chih Hao Hsieh Kanako Ishikawa Yoichiro Sakai Toshiyuki Ishikawa Satoshi Ichise Yoshimasa Yamamoto Ting Chun Kuo Ho Dong Park Norio Yamamura Michio Kumagai 《Aquatic Sciences - Research Across Boundaries》2010,72(4):467-483
We compiled and analyzed long-term data, including chemical, physical and phytoplankton community data, for the Lake Biwa
ecosystem from 1962 to 2003. Analyses on environmental data indicate that Lake Biwa had experienced intensified eutrophication
(according to total phosphorus concentration) in the late 1960s and returned to a less eutrophic status around 1985, and then
exhibited rapid warming and thus increased water column stability since 1990. Total phytoplankton cell volume largely followed
the trend of total phosphorus concentration, albeit short-term fluctuations existed. However, phytoplankton community shifted
dramatically in response to those changes of environmental states. These shifts were cause by changes in trophic status driven
by phosphorus loadings and physical properties in the water column driven by warming. Moreover, most phytoplankton species
did not show a strong linear correlation with environmental variables, suggesting nonlinear transitions among different states. 相似文献
57.
58.
Mikio Shimizu 《Earth, Moon, and Planets》1979,20(3):317-319
The finding of36A excess on Venus by the mass-spectroscopic measurement of the Venus Pioneer appears to endorse the more rapid accretion theory of Venus than the Earth and the secondary origin of the terrestrial atmosphere. 相似文献
59.
60.
Interpretation of landslide distribution triggered by the 2005 Northern Pakistan earthquake using SPOT 5 imagery 总被引:7,自引:4,他引:7
Hiroshi P. Sato Hiroyuki Hasegawa Satoshi Fujiwara Mikio Tobita Mamoru Koarai Hiroshi Une Junko Iwahashi 《Landslides》2007,4(2):113-122
The 2005 northern Pakistan earthquake (magnitude 7.6) of 8 October 2005 occurred in the northwestern part of the Himalayas.
We interpreted landslides triggered by the earthquake using black-and-white 2.5-m-resolution System Pour l’Observation de la Terre 5 (SPOT 5) stereo images. As a result, the counts of 2,424 landslides were identified in the study area of 55 by 51 km. About
79% or 1,925 of the landslides were small (less than 0.5 ha in area), whereas 207 of the landslides (about 9%) were large
(1 ha and more in area). Judging from our field survey, most of the small landslides are shallow rock falls and slides. However,
the resolution and whitish image in the photos prevented interpreting the movement type and geomorphologic features of the
landslide sites in detail. It is known that this earthquake took place along preexisting active reverse faults. The landslide
distribution was mapped and superimposed on the crustal deformation detected by the environmental satellite/synthetic aperture
radar (SAR) data, active faults map, geological map, and shuttle radar topography mission data. The landslide distribution
showed the following characteristics: (1) Most of the landslides occurred on the hanging-wall side of the Balakot–Garhi fault;
(2) greater than one third of the landslides occurred within 1 km from the active fault; (3) the greatest number of landslides
(1,147 counts), landslide density (3.2 counts/km2), and landslide area ratio (2.3 ha/km2) was found within Miocene sandstone and siltstone, Precambrian schist and quartzite, and Eocene and Paleocene limestone and
shale, respectively; (4) there was a slight trend that large landslides occurred on vertically convex slopes rather than on
concave slopes; furthermore, large landslides occurred on steeper (30° and more) slopes than on gentler slopes; (5) many large
landslides occurred on slopes facing S and SW directions, which is consistent with SAR-detected horizontal dominant direction
of crustal deformation on the hanging wall. 相似文献