Small-Amplitude Disturbances In A Radiating And Scattering Grey Medium Ii. Solutions Of Given Real Wave Number <Emphasis Type="BoldItalic">k</Emphasis>     

Noboru?KanekoEmail author  Kazuhiko?Morita  Tetsuya?Satoh  Kimitake?Hayasaki 《Astrophysics and Space Science》2005,299(3):263-306

We study the fundamental modes of radiation hydrodynamic waves arising from one-dimensional small-amplitude initial fluctuations with wave number k in a radiating and scattering grey medium using the Eddington approximation. The dispersion relation analyzed is the same as that of Paper I (Kaneko et al., 2000), but is solved as a quintic in angular frequency ω while a quadratic in k ² in Paper I. Numerical results reveal that wave patterns of five solutions are distinguished into three types of the radiation-dominated and type 1 and type 2 matter-dominated cases. The following wave modes appear in our problem: radiation wave, conservative radiation wave, entropy wave, Newtonian-cooling wave, opacity-damped and cooling-damped waves, constant-volume and constant-pressure diffusion modes, adiabatic sound wave, cooling-damped and drag–force-damped isothermal sound waves, isentropic radiation-acoustic wave, and gap mode. The radiation-dominated case is characterized by the gap between the isothermal sound and isentropic radiation-acoustic speeds within which there is not any acoustic wave propagating with real phase speed. One of the differences between type 1 and type 2 matter-dominated cases is the connectivity of the constant-volume diffusion mode, which originates from the radiative mode in the former case, while from the Newtonian-cooling wave in the latter case. Analytic solutions are derived for all wave modes to discuss their physical significance. The criterion, which distinguishes between radiation-dominated and type 1 matter-dominated cases, is given by Γ₀ = 9, where Γ₀ = C _p ^(tot)/C _V ^(tot) is the ratio of total specific heats at constant pressure and constant volume. Waves in a scattering grey medium are also analyzed, which provides us some hints for the effects of energy and momentum exchange between matter and radiation.  相似文献   

Grade-Tonnage, Ore Value-Tonnage, and Enrichment Ratio-Tonnage Models for Resource Assessment     

Shoji Tetsuya Department of Environment Systems  The University of Tokyo  Tokyo -  Japan 《中国地质大学学报(英文版)》2001,12(1)

I' Grade-tonnage diagrams are one of the most useful tools inthe resource assessment (e. g. St'nger, 1993). One' grade-tonnage diagram is well known as Laskys (1950) e\-7ation, whichdemonstrates the linear relation between average grade (x) andlOgarithms of cumulative ore tonnage (ac above a given gradex(0相似文献   

Seasonal variation in the energy and water exchanges above and below a larch forest in eastern Siberia     

Takeshi Ohta  Tetsuya Hiyama  Hiroki Tanaka  Takashi Kuwada  Trofim C. Maximov  Tetsuo Ohata  Yoshihiro Fukushima 《水文研究》2001,15(8):1459-1476

The water and energy exchanges in forests form one of the most important hydro‐meteorological systems. There have been far fewer investigations of the water and heat exchange in high latitude forests than of those in warm, humid regions. There have been few observations of this system in Siberia for an entire growing season, including the snowmelt and leaf‐fall seasons. In this study, the characteristics of the energy and water budgets in an eastern Siberian larch forest were investigated from the snowmelt season to the leaf‐fall season. The latent heat flux was strongly affected by the transpiration activity of the larch trees and increased quickly as the larch stand began to foliate. The sensible heat dropped at that time, although the net all‐wave radiation increased. Consequently, the seasonal variation in the Bowen ratio was clearly ‘U’‐shaped, and the minimum value (1·0) occurred in June and July. The Bowen ratio was very high (10–25) in early spring, just before leaf opening. The canopy resistance for a big leaf model far exceeded the aerodynamic resistance and fluctuated over a much wider range. The canopy resistance was strongly restricted by the saturation deficit, and its minimum value was 100 s m^?1 (10 mm s^?1 in conductance). This minimum canopy resistance is higher than values obtained for forests in warm, humid regions, but is similar to those measured in other boreal conifer forests. It has been suggested that the senescence of leaves also affects the canopy resistance, which was higher in the leaf‐fall season than in the foliated season. The mean evapotranspiration rate from 21 April 1998 to 7 September 1998 was 1·16 mm day^?1, and the maximum rate, 2·9 mm day^?1, occurred at the beginning of July. For the growing season from 1 June to 31 August, this rate was 1·5 mm day^?1. The total evapotranspiration from the forest (151 mm) exceeded the amount of precipitation (106 mm) and was equal to 73% of the total water input (211 mm), including the snow water equivalent. The understory evapotranspiration reached 35% of the total evapotranspiration, and the interception evaporation was 15% of the gross precipitation. The understory evapotranspiration was high and the interception evaporation was low because the canopy was sparse and the leaf area index was low. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Geochemical evolution of a shallow magma plumbing system during the last 500 years, Miyakejima volcano, Japan: Constraints from U-Th-Ra systematics   总被引：1，自引：0，他引：1  

Tetsuya Yokoyama  Takeshi Kuritani  Eizo Nakamura 《Geochimica et cosmochimica acta》2006,70(11):2885-2901

In order to unravel magma processes and the geochemical evolution of shallow plumbing systems beneath active volcanoes, we investigated U-series disequilibria of rocks erupted over the past 500 years (1469-2000 AD) from Miyakejima volcano, Izu arc, Japan. Miyakejima volcanic rocks show ²³⁸U-²³⁰Th-²²⁶Ra disequilibria with excess ²³⁸U and ²²⁶Ra, due to the addition of slab-derived fluids to the mantle wedge. Basaltic bombs of the 2000 AD eruption have the lowest (²³⁰Th/²³²Th) ratio compared to older Miyakejima eruptives, yielding the youngest ²³⁸U-²³⁰Th model age of 2 kyr. This reinforces our previous model that fluid release from the slab and subsequent magma generation in the mantle wedge beneath Miyakejima occur episodically on a several-kyr timescale. In the last 500 years, Miyakejima eruptives show: (1) a vertical trend in a (²³⁰Th/²³²Th)-(²³⁸U/²³²Th) diagram and (2) a positive linear correlation in a (²²⁶Ra/²³⁰Th)₀ − 1/²³⁰Th diagram, which is also observed in lavas from some of the single eruptions (e.g., 1940, 1962, and 1983 AD). The variations cannot be produced by simple fractional crystallization in a magma chamber with radioactive decay of ²³⁰Th and ²²⁶Ra, but it is possibly produced by synchronous generation of melts in the mantle wedge with different upwelling rate or addition of multiple slab-derived fluids. A much more favorable scenario is that some basaltic magmas were intermittently supplied from deep in the mantle and injected into the crust, subsequently modifying the original magma composition and producing variations in (²³⁰Th/²³²Th) and (²²⁶Ra/²³⁰Th)₀ ratios via assimilation and fractional crystallization (AFC). The assimilant of the AFC process would be a volcanic edifice of previous Miyakejima magmatism. Due to the relatively short timescales involved, the interaction between the assimilant and recent Miyakejima magmatism has not been recorded by the Sr-Nd-Pb isotopic systems. In such cases, Th isotopes and (²²⁶Ra/²³⁰Th) ratio are excellent geochemical tracers of magmatic evolution.  相似文献   

Plume-lithosphere interaction beneath Mt. Cameroon volcano, West Africa: Constraints from U-Th-Ra and Sr-Nd-Pb isotope systematics     

Tetsuya Yokoyama  Festus T. Aka  Minoru Kusakabe 《Geochimica et cosmochimica acta》2007,71(7):1835-1854

Precise measurements of ²³⁸U-²³⁰Th-²²⁶Ra disequilibria in lavas erupted within the last 100 yr on Mt. Cameroon are presented, together with major and trace elements, and Sr-Nd-Pb isotope ratios, to unravel the source and processes of basaltic magmatism at intraplate tectonic settings. All samples possess ²³⁸U-²³⁰Th-²²⁶Ra disequilibria with ²³⁰Th (18-24%) and ²²⁶Ra (9-21%) excesses, and there exists a positive correlation in a (²²⁶Ra/²³⁰Th)-(²³⁰Th/²³⁸U) diagram. The extent of ²³⁸U-²³⁰Th-²²⁶Ra disequilibria is markedly different in lavas of individual eruption ages, although the (²³⁰Th/²³²Th) ratio is constant irrespective of eruption age. When U-series results are combined with Pb isotope ratios, negative correlations are observed in the (²³⁰Th/²³⁸U)-(²⁰⁶Pb/²⁰⁴Pb) and (²²⁶Ra/²³⁰Th)-(²⁰⁶Pb/²⁰⁴Pb) diagrams. Shallow magma chamber processes like magma mixing, fractional crystallization and wall rock assimilation do not account for the correlations. Crustal contamination is not the cause of the observed isotopic variations because continental crust is considered to have extremely different Pb isotope compositions and U/Th ratios. Melting of a chemically heterogeneous mantle might explain the Mt. Cameroon data, but dynamic melting under conditions of high D_U and D_U/D_Th, long magma ascent time, or disequilibrium mineral/melt partitioning, is required. The most plausible scenario to produce the geochemical characteristics of Mt. Cameroon samples is the interaction of melt derived from the asthenospheric mantle with overlying sub-continental lithospheric mantle which has elevated U/Pb (>0.75) and Pb isotope ratios (²⁰⁶Pb/²⁰⁴Pb > 20.47) due to late Mesozoic metasomatism.  相似文献   

Ultra-rapid earth rotation determination with VLBI during CONT11 and CONT14     

Rüdiger Haas  Thomas Hobiger  Shinobu Kurihara  Tetsuya Hara 《Journal of Geodesy》2017,91(7):831-837

We present earth rotation results from the ultra-rapid operations during the continuous VLBI campaigns CONT11 and CONT14. The baseline Onsala–Tsukuba, i.e., using two out of the 13 and 17 stations contributing to CONT11 and CONT14, respectively, was used to derive UT1-UTC in ultra-rapid mode during the ongoing campaigns. The latency between a new observation and a new UT1-UTC result was less than 10 min for more than 95% of the observations. The accuracy of the derived ultra-rapid UT1-UTC results is approximately a factor of three worse than results from optimized one-baseline sessions and/or complete analysis of large VLBI networks. This is, however, due to that the one-baseline picked from the CONT campaigns is not optimized for earth rotation determination. Our results prove that the 24/7 operation mode planned for VGOS, the next-generation VLBI system, is possible already today. However, further improvements in data connectivity of stations and correlators as well in the automated analysis are necessary to realize the ambitious VGOS plans.  相似文献   

Verification of vertically generalized production model and estimation of primary production in Sagami Bay,Japan     

Joji Ishizaka  Eko Siswanto  Tetsuya Itoh  Hiroshi Murakami  Yukuya Yamaguchi  Naho Horimoto  Takashi Ishimaru  Shinji Hashimoto  Toshiro Saino 《Journal of Oceanography》2007,63(3):517-524

The Vertically Generalized Production Model (VGPM) was verified by the primary production data of the Sagami Bay, Japan. The VGPM with open ocean parameters including P ^B _opt , maximum primary production per unit of chlorophyll a in the water column, explained only 40% of the variability of integrated primary production. Formulations of the open ocean P ^B _opt showed no correlation with in situ P ^B _opt . Adjustment of the parameters of chlorophyll a and temperature dependent P ^B _opt improved the estimation of integrated primary production to 47% of the variation. Vertical integration parameters of VGPM also have to be adjusted to improve the estimation. Integrated primary production calculated with a stronger light dependency and with the adjusted P ^B _opt model can explain 74% of the variation. This model was used to estimate primary production of the Sagami Bay during 2003 with satellite data. In situ measurements on cloudy days indicate that the use of satellite data from sunny days only overestimates primary production.  相似文献   

A Linearized k-\epsilon Model of Forest Canopies and Clearings     

Antonio Segalini  Tetsuya Nakamura  Koji Fukagata 《Boundary-Layer Meteorology》2016,161(3):439-460

  相似文献   

Effects of climate change on potential habitats of the cold temperate coniferous forest in Yunnan province,southwestern China     

Wang-jun Li  Ming-chun Peng  Motoki Higa  Nobuyuki Tanaka  Tetsuya Matsui  Cindy Q. Tang  Xiao-kun Ou  Rui-wu Zhou  Chong-yun Wang  Hai-zhong Yan 《山地科学学报》2016,13(8):1411-1422

We built a classification tree(CT) model to estimate climatic factors controlling the cold temperate coniferous forest(CTCF) distributions in Yunnan province and to predict its potential habitats under the current and future climates, using seven climate change scenarios, projected over the years of 2070-2099. The accurate CT model on CTCFs showed that minimum temperature of coldest month(TMW) was the overwhelmingly potent factor among the six climate variables. The areas of TMW-4.05 were suitable habitats of CTCF, and the areas of -1.35 TMW were non-habitats, where temperate conifer and broad-leaved mixed forests(TCBLFs) were distribute in lower elevation, bordering on the CTCF. Dominant species of Abies, Picea, and Larix in the CTCFs, are more tolerant to winter coldness than Tsuga and broad-leaved trees including deciduous broad-leaved Acer and Betula, evergreen broadleaved Cyclobalanopsis and Lithocarpus in TCBLFs. Winter coldness may actually limit the cool-side distributions of TCBLFs in the areas between -1.35°C and -4.05°C, and the warm-side distributions of CTCFs may be controlled by competition to the species of TCBLFs. Under future climate scenarios, the vulnerable area, where current potential(suitable + marginal) habitats(80,749 km~2) shift to nonhabitats, was predicted to decrease to 55.91%(45,053 km~2) of the current area. Inferring from the current vegetation distribution pattern, TCBLFs will replace declining CTCFs. Vulnerable areas predicted by models are important in determining priority of ecosystem conservation.  相似文献   

Chert–clastic sequence in the Cretaceous Shimanto Accretionary Complex on the central Kii Peninsula,SW Japan     

Yusuke Shimura  Makoto Takeuchi  Tetsuya Tokiwa 《Island Arc》2020,29(1)

Ocean plate stratigraphy (OPS) within an ancient accretionary complex provides important information for understanding the history of an oceanic plate from its origin at a mid‐ocean ridge to its subduction at a trench. Here, we report a recently discovered chert–clastic sequence (CCS) that comprises a continuous succession from pelagic sediments to terrigenous clastics and which constitutes part of the OPS in the Akataki Complex within the Cretaceous Shimanto Accretionary Complex on the central Kii Peninsula, SW Japan. As well as describing this sequence, we present U–Pb ages of detrital zircons from terrigenous clastic rocks in the CCS, results for which show that the youngest single grain and youngest cluster ages belong to the Santonian–Campanian and are younger than the radiolarian age from the underlying pelagic sedimentary rock (late Albian–Cenomanian). Thus, the CCS records the movement history of the oceanic plate from pelagic sedimentation (until the late Albian–Cenomanian) to a terrigenous sediment supply (Santonian–Campanian).  相似文献