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21.
To determine depth dependence of permeability in various geologic deposits, exponential models have often been proposed. However, spatial variability in hydraulic conductivity, K, rarely fits this trend in coarse alluvial aquifers, where complex stratigraphic sequences follow unique trends due to depositional and post-depositional processes. This paper analyzes K of alluvial-fan gravel deposits in several boreholes, and finds exponential decay in K with depth. Relatively undisturbed gravel cores obtained in the Toyohira River alluvial fan, Sapporo, Japan, are categorized by four levels of fine-sediment packing between gravel grains. Grain size is also analyzed in cores from two boreholes in the mid-fan and one in the fan-toe. Profiles of estimated conductivity, $ \overline{K} $ , are constructed from profiles of core properties through a well-defined relation between slug-test results and core properties. Errors in $ \overline{K} $ are eliminated by a moving-average method, and regression analysis provides the decay exponents of $ \overline{K} $ with depth. Moving-average results show a similar decreasing trend in only the mid-fan above ～30-m depth, and the decay exponent is estimated as ≈0.11 m?1, which is 10- to 1,000-fold that in consolidated rocks. A longitudinal cross section is also generated by using the profiles to establish hydrogeologic boundaries in the fan. 相似文献
22.
The thermal inertia values of Saturn’s main rings (the A, B, and C rings and the Cassini division) are derived by applying our thermal model to azimuthally scanned spectra taken by the Cassini Composite Infrared Spectrometer (CIRS). Model fits show the thermal inertia of ring particles to be 16, 13, 20, and 11 J m−2 K−1 s−1/2 for the A, B, and C rings, and the Cassini division, respectively. However, there are systematic deviations between modeled and observed temperatures in Saturn’s shadow depending on solar phase angle, and these deviations indicate that the apparent thermal inertia increases with solar phase angle. This dependence is likely to be explained if large slowly spinning particles have lower thermal inertia values than those for small fast spinning particles because the thermal emission of slow rotators is relatively stronger than that of fast rotators at low phase and vise versa. Additional parameter fits, which assume that slow and fast rotators have different thermal inertia values, show the derived thermal inertia values of slow (fast) rotators to be 8 (77), 8 (27), 9 (34), 5 (55) J m−2 K−1 s−1/2 for the A, B, and C rings, and the Cassini division, respectively. The values for fast rotators are still much smaller than those for solid ice with no porosity. Thus, fast rotators are likely to have surface regolith layers, but these may not be as fluffy as those for slow rotators, probably because the capability of holding regolith particles is limited for fast rotators due to the strong centrifugal force on surfaces of fast rotators. Other additional parameter fits, in which radii of fast rotators are varied, indicate that particles less than ∼1 cm should not occupy more than roughly a half of the cross section for the A, B, and C rings. 相似文献
23.
Zhao Kai Zhao Haikun Raga Graciela B. Yoshida Ryuji Wang Weiqiang Klotzbach Philip J. 《Climate Dynamics》2021,56(1-2):515-535
Climate Dynamics - This study examines extended boreal summer (May–October) tropical cyclogenesis events (TCGEs) associated with large-scale flow patterns (LFPs) over the western North... 相似文献
24.
Simulations of dense planetary rings: IV. Spinning self-gravitating particles with size distribution
Previous self-gravitating simulations of dense planetary rings are extended to include particle spins. Both identical particles as well as systems with a modest range of particle sizes are examined. For a ring of identical particles, we find that mutual impact velocity is always close to the escape velocity of the particles, even if the total rms velocity dispersion of the system is much larger, due to collective motions associated to wakes induced by near-gravitational instability or by viscous overstability. As a result, the spin velocity (i.e., the product of the particle radius and the spin frequency) maintained by mutual impacts is also of the order of the escape velocity, provided that friction is significant. For the size distribution case, smaller particles have larger impact velocities and thus larger spin velocities, particularly in optically thick rings, since small particles move rather freely between wakes. Nevertheless, the maximum ratio of spin velocities between the smallest and largest particles, as well as the ratio for translational velocities, stays below about 5 regardless of the width of the size distribution. Particle spin state is one of the important factors affecting the temperature difference between the lit and unlit face of Saturn's rings. Our results suggest that, to good accuracy, the spin frequency is inversely proportional to the particle size. Therefore, the mixing ratio of fast rotators to slow rotators on the scale of the thermal relaxation time increases with the width of the particle size distribution. This will offer means to constrain the particle size distribution with the systematic thermal infrared observations carried by the Cassini probe. 相似文献
25.
Tomoki NAKAMURA Michael ZOLENSKY Minoru SEKIYA Ryuji OKAZAKI Keisuke NAGAO 《Meteoritics & planetary science》2003,38(2):243-250
Abstract— A fine‐grained dark inclusion in the Ningqiang carbonaceous chondrite consists of relatively pristine solar nebular materials and has high concentrations of heavy primordial rare gases. Trapped 36Ar concentration amounts to 6 times 10?6 cc STP/g, which is higher than that of Ningqiang host by a factor of three. Light HF‐HCl etching of the dark inclusion removed 86, 73, and 64% of the primordial 36Ar, 84Kr, and 132Xe, respectively. Thus, the majority of the noble gases in this inclusion are located in very acid‐susceptive material. Based on the elemental composition, the noble gases lost from the dark inclusion during the acid‐treatments are Ar‐rich, and the noble gases remaining in the inclusion are Q and HL gases. Transmission electron microscopy showed that the acid treatments removed thin Si, Mg, and Fe‐rich amorphous rims present around small olivine and pyroxene grains in the dark inclusion, suggesting that the Ar‐rich gases reside in the amorphous layers. A possible origin of the Ar‐rich gases is the acquisition of noble‐gas ions with a composition fractionated relative to solar abundance favoring the heavy elements by the effect of incomplete ionization under plasma conditions at 8000 K electron temperature. 相似文献
26.
The Asian monsoon is one of the largest climatic systems in the world, but age of its onset has been estimated differently ranging from the late Eocene to the Quaternary. We investigated the sedimentology and stable isotopic compositions of the upper Eocene Jiuziyan Formation, a terrestrial limestone unit in the Jianchuan basin, Yunnan Province in China. This limestone formation is restricted in several localities in the central part of the basin. Previously, this has been characterized as palustrine carbonate and the transition to the sublacustrine deposit of the overlying Shuanghe Formation was interpreted as the appearance of wetter climate during the late Eocene. Our observations of macro- and microfacies revealed sedimentary fabrics indicating rapid CaCO3 precipitation, such as dendritic calcite and calcified reed stems, which are unlikely to develop in a simple lacustrine setting. High carbonate content (mostly >90 %) and restricted distribution of the Jiuziyan limestone indicate a depositional setting spatially limited and isolated from clastic influx. These findings, together with clearly higher δ13C values (−0.7 ‰ to +6.9 ‰) and lower δ18O values (−14.6 ‰ to −10.5 ‰) than those of the Shuanghe Formation, indicate that the limestone was mainly travertine, carbonate formed from endogenic spring water. The elevated δ13C resulted from a large amount of CO2 degassing from spring water with high pCO2. In addition, the occurrence of centimeter-scale lamination coupled with cyclic changes in δ13C and δ18O is almost identical with the modern annually-laminated travertine reported from Baishuitai in northern Yunnan Province, implying comparable amplitude of seasonal temperature and precipitation changes to the record of the modern travertine at Baishuitai. Our results do not contradict the previous interpretation of late Eocene wetting and additionally suggest the existence of the late Eocene monsoon climate in the Jianchuan basin. 相似文献
27.
Tsuyoshi Yoshioka Michinobu Furukawa Koji Yoshizaki Ryuji Matsuhashi Yoshikuni Yoshida 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(5):677-683
Recently, energy service providers (ESP) have increased due to deregulation in the power market. They install energy supply
equipment at their own cost and supply the necessary energy to the client. The Tokyo Metropolitan Government started Asia’s
first cap-and-trade program in April 2010. This program caps energy-related carbon dioxide emissions from some 1,330 offices
and factories in Tokyo. Then, ESPs have to manage the many risks of energy service project directly linked to the profits.
In this paper, we describes the risk analysis and investment optimization for energy service projects using financial engineering. 相似文献
28.
Marion Ferrat Dominik J. Weiss Stanislav Strekopytov Hongyun Chen Youbin Sun Ryuji Tada 《Geochimica et cosmochimica acta》2011,75(21):6374-6399
The Asian Monsoon forms an important part of the earth’s climate system, yet our understanding of the past interactions between its different sub-systems, the East Asian and Indian monsoons, and between monsoonal winds and other prevailing wind currents such as the Westerly jet, is limited, particularly in central Asia. This in turn affects our ability to develop climate models capable of accurately predicting future changes in atmospheric circulation patterns and monsoon intensities in Asia. Provenance studies of mineral dust deposited in terrestrial settings such as peat bogs can address this problem directly, by offering the possibility to examine past deposition rates and wind direction, and hence reconstruct past atmospheric circulation patterns. However, such studies are challenged by several issues, most importantly the identification of proxies that unambiguously distinguish between the different potential dust sources and that are independent of particle size. In addition, a single analytical method that is suitable for sample preparation of both dust source (i.e. desert sand, soil) and receptor (i.e. dust archive such as peat or soil profiles) material is desirable in order to minimize error propagation derived from the experimental and analytical work. Here, an improved geochemical framework of provenance tracers to study atmospheric circulation patterns and palaeomonsoon variability in central Asia is provided, by combining for the first time mineralogical as well as major and trace elemental (Sc, Y, Th and the rare earth elements) information on Chinese (central Chinese loess plateau, northern Qaidam basin and Taklamakan, Badain Juran and Tengger deserts), Indian (Thar desert) and Tibetan (eastern Qinghai-Tibetan Plateau) dust sources.Quartz, feldspars and clay minerals are the major constituents of all studied sources, with highly variable calcite contents reflected in the CaO concentrations. Chinese and Tibetan dust sources are enriched in middle REE relative to the upper continental crust and average shale but the Thar desert has a REE signature distinctly different from all other dust sources. There are significant differences in major, trace and REE compositions between the coarse and fine fractions of the surface sands, with the finest <4 μm fraction enriched in Al2O3, Fe2O3, MnO, MgO and K2O and the <32 μm fractions in Sc, Y, Th and the REE relative to the coarse fractions. The <4 μm fraction best represents the bulk REE geochemistry of the samples. The provenance tracers Y/∑REE, La/Er, La/Gd, Gd/Er, La/Yb, Y/Tb, Y/La, Y/Nd and to a certain extent the europium anomaly Eu/Eu∗ (all REE normalized to post-Archean Australian shale, PAAS) are particle size-independent tracers, of which combinations of Y/∑REE, La/Yb, Y/Tb, Y/La and Eu/Eu∗ can be used to distinguish the Thar desert, the Chinese deserts, the Chinese loess plateau and the Tibetan soils. Their independence upon grain size means that these tracers can be applied to the long-range provenance tracing of Asian dust even when only bulk samples are available in the source region. Combinations of La/Th, Y/Tb, Y/∑REE, Sc/La and Y/Er distinguish the Tibetan soils from the Chinese loess plateau and the Chinese deserts. La/Th and notably Th/∑REE isolate the signature of the Badain Juran desert and the combination of Sc/La and Y/Er that of the Taklamakan desert. The similarity in all trace and REE-based provenance tracers between the northern Qaidam basin and Tengger desert suggests that these two deposits may have a common aeolian source. 相似文献
29.
Ryuji Tateyama Eiji Ohtani Hidenori Terasaki Keisuke Nishida Yuki Shibazaki Akio Suzuki Takumi Kikegawa 《Physics and Chemistry of Minerals》2011,38(10):801-807
The compositional dependence on the density of liquid Fe alloys under high pressure is important for estimating the amount
of light elements in the Earth’s outer core. Here, we report on the density of liquid Fe–Si at 4 GPa and 1,923 K measured
using the sink–float method and our investigation on the effect of the Si content on the density of the liquid. Our experiments
show that the density of liquid Fe–Si decreases from 7.43 to 2.71 g/cm3 non-linearly with increasing Si content (0–100 at%). The molar volume of liquid Fe–Si calculated from the measured density
gradually decreases in the compositional range 0–50 at% Si, and increases in the range 50–100 at% Si. It should be noted that
the estimated molar volume of the alloys shows a negative volume of mixing between Fe and Si. This behaviour is similar to
Fe–S liquid (Nishida et al. in Phys Chem Miner 35:417–423, 2008). However, the excess molar volume of mixing for the liquid Fe–Si is smaller than that of liquid Fe–S. The light element
contents in the outer core estimated previously may be an underestimation if we take into account the possible negative value
of the excess mixing volume of iron–light element alloys in the outer core. 相似文献
30.
Abstract In situ stress was measured close to the fault associated with the 1995 Kobe Earthquake (Hyogo-ken Nanbu earthquake; January 1995; M 7.2) using the hydraulic fracturing method. The measurements were made approximately 2 years after the earthquake. The measured points were approximately 40 m from the fault plane at depths of about 1500 m. The maximum and the minimum horizontal compressive stresses were 45 MPa and 31 MPa, respectively. The maximum compressive stress and the maximum shear stress are very small in comparison with those of other seismically active areas. The azimuth of the maximum horizontal compressive stress was estimated from the observed azimuths of well bore breakouts at depths between 1400 m and 1600 m and was found to be N135° (clockwise). The maximum stress axis is perpendicular to the fault strike, N45°. These features are interpreted in terms of a small frictional coefficient of the fault. The shear stress on the fault was released and dropped almost to zero during the earthquake and it has not yet recovered. Zero shear stress on the fault plane resulted from the perpendicular orientation of one of the principal stress to the fault plane. 相似文献