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排序方式: 共有107条查询结果,搜索用时 15 毫秒
41.
Tae-Soo Pyo Masahiko Hayashi Naoto Kobayashi Alan T. Tokunaga Hiroshi Terada Miwa Goto Takuya Yamashita Yoichi Itoh Hideki Takami Naruhisa Takato Yutaka Hayano Wolfgang Gaessler Yukiko Kamata Yosuke Minowa Masanori Iye 《Astrophysics and Space Science》2003,287(1-4):21-24
We present high angular resolution spectra taken along the jets from L1551 IRS 5 and DG Tau obtained with the Subaru Telescope. The position-velocity diagrams of the [Fe II] λ 1.644 μmemission line revealed remarkably similar characteristics for the two sources, showing two distinct velocity components separated from each other in both velocity and space with the entire emission range blueshifted with respect to the stellar velocity. The high velocity component (HVC) has a velocity of –200 ––300 km s-1 with a narrow line width, while the low velocity component (LVC) is around –100 km s-1 exhibitinig a broad line width. The HVC is located farther away from the origin and is more extended than the LVC. Our results suggest that the HVC is a well-collimated jet originating from the region close to the star, while the LVC is a widely-opened wind accelerated in the region near the inner edge of the accretion disk. 相似文献
42.
Recovery of entire shocked samples in a range of pressure from ~100 GPa to Hugoniot elastic limit
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Keita Nagaki Toshihiko Kadono Tatsuhiro Sakaiya Tadashi Kondo Kosuke Kurosawa Yoichiro Hironaka Keisuke Shigemori Masahiko Arakawa 《Meteoritics & planetary science》2016,51(6):1153-1162
We carried out laser shock experiments and wholly recovered shocked olivine and quartz samples. We investigated the petrographic features based on optical micrographs of sliced samples and found that each recovered sample comprises three regions, I (optically dark), II (opaque), and III (transparent). Scanning electron microscopy combined with electron backscattered diffraction shows that there are no crystal features in the region I; the materials in the region I have once melted. Moreover, numerical calculations performed with the iSALE shock physics code suggest that the boundary between regions II and III corresponds to Hugoniot elastic limit (HEL). Thus, we succeeded in the recovery of the entire shocked samples experienced over a wide range of pressures from HEL (~10 GPa) to melting pressure (~100 GPa) in a hierarchical order. 相似文献
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Gatot E. Susilo Koichi Yamamoto Tsuyoshi Imai Yoshiyuki Ishii Hiroshi Fukami Masahiko Sekine 《水文科学杂志》2013,58(3):539-548
Abstract The effect of the El Niño Southern Oscillation (ENSO) on rainfall characteristics in the tropical peatland areas of Central Kalimantan, Indonesia, is demonstrated. This research used rainfall data collected between 1978 and 2008. The results suggest a relationship between ENSO events and the trend in rainfall observed in the study area. Further analyses show that El Niño events have a stronger effect on the rainfall compared to La Niña events. El Niño events were also correlated to the increase in the number of days with less than 1 mm of rainfall in the dry season. The analysis reveals that the impact of El Niño events on rainfall in dry seasons is intensifying annually. Furthermore, ENSO events are not the only factors affecting rainfall trends in the observed area. Other factors, such as deforestation, may also affect the trend. Editor Z.W. Kundzewicz Citation Susilo, G.E., Yamamoto, K., Imai, T., Ishii, Y., Fukami, H., and Sekine, M., 2013. The effect of ENSO on rainfall characteristics in the tropical peatland areas of Central Kalimantan, Indonesia. Hydrological Sciences Journal, 58 (3), 539–548. 相似文献
45.
At the head of Tokyo Bay, coastal upwelling of oxygen-depleted bottom water, induced by northeasterly wind-driven circulation, sometimes leads to the deaths of many shellfish and other aquatic animals across large areas, resulting in substantial economic losses to coastal fisheries. One of the chemical actions associated with this dynamic process is the oxidation of hydrogen sulfide in the bottom water into a colloidal sulfur substance. When sunshine reflects off surface water containing these sulfur particles, the seawater appears milky blue. This phenomenon has been termed “Aoshio.” One of the most important issues to address concerning upwelling in relation to Aoshio is to accurately predict when it will occur as well as its area and scale. In the preliminary study described here, we propose criteria for the occurrence of wind-driven upwelling associated with Aoshio on the southeast shore of Tokyo Bay using two analytical solutions. These two solutions were derived based on some specific assumptions in the context of a two-layered fluid. Comparison with observation data suggested that the criteria were valid. The results of analyses of the sensitivity of the solutions to all of the parameters incorporated into them were also found to be in accord with our qualitative understanding of this phenomenon. 相似文献
46.
The availability of an equation to evaluate the influence of multiple scattering in the single scattering process corresponding
to a layer of arbitrary optical thickness was established. In order to confirm the validity of this equation, the radiance
distribution in this layer was computed using a plane–parallel layer model based on the successive order of scattering method.
The relative errors in a radiance distribution computed were evaluated as a function of optical thickness by the derived equation.
It was shown that this equation provides a theoretical background for determining layer thickness using the plane–parallel
layer model. 相似文献
47.
Multispectral satellite remote sensing can predict shallow-water depth distribution inexpensively and exhaustively, but it requires many in situ measurements for calibration. To extend its feasibility, we improved a recently developed technique, for the first time, to obtain a generalized predictor of depth. We used six WorldView-2 images and obtained a predictor that yielded a 0.648 m root-mean-square error against a dataset with a 5.544 m standard deviation of depth. The predictor can be used with as few as two pixels with known depth per image, or with no depth data, if only relative depth is needed. 相似文献
48.
Impact experiments of inhomogeneous targets such as layered bodies consisting of a dense core and porous mantle were conducted to clarify the effect of the layered structure on impact strength. The layered structure of small bodies could be the result of the thermal evolution of planetesimals in the solar nebula. So, the impact disruption of thermally evolved bodies with core-mantle structure is important for the origin of small bodies such as asteroids. We investigated the impact strength of rocky-layered bodies with porous mantle-sintered cores, which could be formed at an initial stage of thermal evolution. Spherical targets composed of soda-lime glass or quartz core and porous gypsum mantle were prepared as an analog of small bodies with a core-mantle structure, and the internal structure was changed. A nylon projectile was impacted at the impact velocity from 1 to 5 km/s. The impact strength of the core-mantle targets decreases with the increase of the core/target mass ratio (RCM) in the specific energy range from 1×103 to 4×104 J/kg. We observed two distinct destruction modes characterized by the damage to the core: one shows a damaged core and fractured mantle, and the other shows an intact core and broken mantle. The former mode was usually observed with increasing RCM, and the boundary condition of the core destruction () was experimentally found to be , where is the specific energy required to disrupt a glass core. From this empirical equation, it might be possible to discuss the destruction conditions of a thermally evolved body with a porous mantle-sintered core structure. We speculate that the impact strength of the body could be significantly reduced with the progress of internal evolution at the initial stage of thermal evolution. 相似文献
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50.
Simulated biogeochemical responses to iron enrichments in three high nutrient, low chlorophyll (HNLC) regions 总被引:1,自引:0,他引:1
To fill temporal gaps in iron-enrichment experimental data and gain further understanding of marine ecosystem responses to iron enrichments, we apply a fifteen-compartment ecosystem model to three iron-enrichment sites, namely SEEDS (the Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study; 48.5°N, 165°E) in the western North Pacific, SOIREE (the Southern Ocean Iron RElease Experiment; 61°S, 140°E) in the Southern Ocean, and IronExII (the second mesoscale iron enrichment experiment; 3.5°S, 104°W) in the Equatorial Pacific. The ecological effects of iron in the model are represented by changing two photosynthetic parameters during the iron-enrichment period. The model results successfully reproduce the observed biogeochemical responses inside and outside the iron patch at each site, such as rapid increases in plankton biomass and biological productivity, and decreases in surface nutrients and pCO2, inside the patch. However, the modeled timing and magnitude of changes differ among the sites because of differences in both physical environments and plankton species. After the iron enrichment, the diatom productivity is strongly controlled by light at SOIREE and by silicate at IronExII and SEEDS. Light limitation due to self-shading by the phytoplankton is significant during the bloom at all sites. Sensitivity analysis of the model results to duration of the iron enrichment reveals that long-term multiple infusions over more than a week would not be effective at SEEDS because of strong silicate limitation on diatom growth. Sensitivity of the model to water temperature shows that export production is higher at lower temperatures, because of slower recycling of particulate organic carbon. Therefore, the e-ratio (the ratio of export production to primary production) is inversely correlated with temperature, and the relationship can be described with a linear function. Through this study, we conclude that ecosystem modeling is a powerful tool to help design future iron-enrichment experiments and observational plans. 相似文献