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111.
The stability limit of coplanar hierarchical triple systems is numerically studied. Systems we investigated consist of two equal mass bodies initially on a circular orbit and third body with various masses, which at the maximum are equal to the mass of the binary. In order to estimate the stability limit, we use an empirically-found fact that the system is quasi-periodic if the initial eccentricity of the outer binary is less than some critical value, otherwise the third body eventually escapes. We make an analytical expression for the stability limit in terms of the ratio of the orbital radii and find that the expression improves the previous criteria. The resultant expression also suggests that the ratio of the orbital radii rapidly approaches to a certain value (e.g. $\sim $ 2, in an initially circular outer binary) as the mass of the third-body tends to zero. 相似文献
112.
M. M. Saito K. Tanikawa V. V. Orlov 《Celestial Mechanics and Dynamical Astronomy》2012,112(3):235-251
The stability of hierarchical triple system is studied in the case of an extrasolar planet or a brown dwarf orbiting a pair
of main sequence stars. The evolution of triple system is well modelled by random walk (RW) diffusion, particularly in the
cases where the third body is small and tracing an orbit with a large eccentricity. A RW model neglects the fact that there
are many periodic orbits accompanied by stability islands, and hence inherently overestimates the instability of the system.
The present work is motivated by the hope to clarify how far the RW model is applicable. Escape time and the surface section
technique are used to analyse the outcome of numerical integrations. The analysis shows that the RW-like model explains escape
of the third body if the initial configuration is directly outside of the KAM tori. A small gap exists in (q
2/a
1, e
2)-plane between locations of the stability limit curves based on our numerical study and on RW-model (the former is shifted
by –1.4 in q
2/a
1 direction from the latter). 相似文献
113.
Microbes are ubiquitous in groundwater systems, and they play an important role in the redox state of groundwater and especially
on the fate of organic contaminants. In this context, numerical simulations that couple microbial processes to reactive transport
models are becoming more popular. In the present work, we revisit the mathematical ground of microbial redox reactions and
perform a benchmark analysis of the simulation of aerobic benzene degradation in a shallow and oxidizing aquifer. Numerical
results indicate that the two codes tested (one using the finite elements approach and the other using the finite differences
approach) lead to very similar results. In addition, the coupling of heterogeneous geochemical reactions to the benchmarked
example problem provides a solid basis for the understanding of the redox reactions and the changes on the carbon system triggered
by the aerobic degradation of benzene. 相似文献
114.
Satoshi Saito Makoto Arima Takashi Nakajima Kenichiro Tani Takashi Miyazaki Ryoko Senda Qing Chang Toshiro Takahashi Yuka Hirahara Jun-Ichi Kimura 《Contributions to Mineralogy and Petrology》2012,163(4):611-629
The Miocene Kaikomagatake pluton is one of the Neogene granitoid plutons exposed in the Izu Collision Zone, which is where
the juvenile Izu-Bonin oceanic arc is colliding against the mature Honshu arc. The pluton intrudes into the Cretaceous to
Paleogene Shimanto accretionary complex of the Honshu arc along the Itoigawa-Shizuoka Tectonic Line, which is the collisional
boundary between the two arcs. The pluton consists of hornblende–biotite granodiorite and biotite monzogranite, and has SiO2 contents of 68–75 wt%. It has high-K series compositions, and its incompatible element abundances are comparable to the average
upper continental crust. Major and trace element compositions of the pluton show well-defined chemical trends. The trends
can be interpreted with a crystal fractionation model involving the removal of plagioclase, biotite, hornblende, quartz, apatite,
and zircon from a potential parent magma with a composition of ~68 wt% SiO2. The Sr isotopic compositions, together with the partial melting modeling results, suggest that the parent magma is derived
by ~53% melting of a hybrid lower crustal source comprising ~30% Shimanto metasedimentary rocks of the Honshu arc and ~70%
K-enriched basaltic rocks of the Izu-Bonin rear-arc region. Together with previous studies on the Izu Collision Zone granitoid
plutons, the results of this study suggest that the chemical diversity within the parental magmas of the granitoid plutons
reflects the chemical variation of basaltic sources (i.e., across-arc chemical variation in the Izu-Bonin arc), as well as
a variable contribution of the metasedimentary component in the lower crustal source regions. In addition, the petrogenetic
models of the Izu Collision Zone granitoid plutons collectively suggest that the contribution of the metasedimentary component
is required to produce granitoid magma with compositions comparable to the average upper continental crust. The Izu Collision
Zone plutons provide an exceptional example of the transformation of a juvenile oceanic arc into mature continental crust. 相似文献
115.
Daniel Brown Keiko Saito Meng Liu Robin Spence Emily So Michael Ramage 《Bulletin of Earthquake Engineering》2012,10(3):741-764
The M7.9 Wenchuan earthquake on May 12th, 2008 was the most destructive in China since 1976. The event caused huge damage and loss of life and exposed weaknesses both in the formulation and implementation of the regulations governing building in the affected provinces. Following the earthquake a massive relief and recovery operation was mounted by the Chinese government. The authors took part in field studies in the affected area which took place 5 and 11?months after the event, at which time recovery operations were well-advanced. The aims of the study were to assess the effects caused by the earthquake to the built environment and society, to collect information on the ongoing recovery efforts and future plans, and to demonstrate the use of tools that allow the collection of spatially referenced damage and recovery data. Based on available satellite imagery supplemented by ground observation, geodatabases were constructed containing information on damage and recovery in several parts of the affected area. The paper gives an overview of the recovery process, describes the methods used to construct these geodatabases, and offers some analysis of the data obtained. It is argued that such databases have great potential for the management of post-disaster recovery and for creating a permanent record of the recovery process. 相似文献
116.
新疆乌恰县乌拉根铅锌矿床地质特征和S-Pb同位素组成 总被引:5,自引:0,他引:5
乌拉根矿床是喀什中新生界凹陷内新近勘查的具超大型远景的铅锌矿床。铅锌矿体呈板状,顺层分布于乌拉根向斜南、北两翼,容矿地层为下白垩统克孜勒苏群第五岩性段(K1kz5)褪色灰白色砂砾岩及古新统阿尔塔什组(E1a)泥质白云岩。矿石具块状、微细浸染状、细脉状、团斑状等构造及胶结结构、交代反映边结构等。乌拉根矿床硫化物δ34S值为-27.9‰~14.6‰,指示相邻层位中石膏、天青石等硫酸盐提供硫,同时有机物的热分解也可能作为硫的来源,硫的还原可能包括生物还原与有机质热化学还原两种模式。硫化物的206Pb/204Pb、207Pb/204Pb、208Pb/204Pb分别为18.528~18.663、15.611~15.669、38.616~38.839,极为均一,指示上地壳和造山带剥蚀区是成矿金属的来源。综合分析乌拉根铅锌矿床地质、地球化学特征,并与已有成因认识进行对比,判定乌拉根矿床是与盆地流体活动相关的砂岩型铅锌矿床。 相似文献
117.
Yuko Suto Sosuke Saito Ken-ichi Osada Hiroshi Takahashi Hideaki Motoyama Yoshiyuki Fujii Yoichi Tanaka 《Polar Science》2008,2(1):15-26
A next-generation drilling system, equipped with a thermal drilling device, is proposed for glacier ice. The system is designed to penetrate glacier ice via melting of the ice and continuously analyze melt-water in a contamination-free sonde. This new type of drilling system is expected to provide analysis data in less time and at less cost than existing systems. Because of the limited number of parameters that can be measured, the proposed system will not take the place of conventional drilling systems that are used to obtain ice cores; however, it will provide a useful method for quickly and simply investigating glacier ice.An electro-thermal drilling device is one of the most important elements needed to develop the proposed system. To estimate the thermal supply required to reach a target depth in a reasonable time, laboratory experiments were conducted using ice blocks and a small sonde equipped solely with heaters. Thermal calculations were then performed under a limited range of conditions. The experiments were undertaken to investigate the effects of the shape and material of the drill head and heater temperature on the rate of penetration into the ice. Additional thermal calculations were then performed based on the experimental results.According to the simple thermal calculations, if the thermal loss that occurs while heat is transferred from the heater to ice (in melting the ice) is assumed to be 50%, the total thermal supply required for heaters in the sonde and cable is as follows: (i) 4.8 kW (sonde) plus 0 W (cable) to penetrate to 300 m depth over 10 days into temperate glacier ice for which the temperature is 0 °C at all depths and to maintain a water layer along 300 m of cable; (ii) 10 kW (sonde) plus 19–32 kW (cable) to penetrate to 1000 m depth over 1 month into cold glacier ice for which the temperature is −25 °C at the surface and 0 °C at 1000 m depth and to maintain a water layer along 1000 m of cable; and (iii) 19 kW (sonde) plus 140–235 kW (cable) to penetrate to 3000 m depth over 2 months into an ice sheet for which the temperature is −55 °C at the surface and 0 °C at 3000 m depth and to maintain a water layer along 3000 m of cable. The thermal supply required for the cable is strongly affected by the thickness of the water layer, cable diameter, and the horizontal distance from the ice wall at which the ice temperature was maintained at its initial temperature. A large thermal supply is required to heat 3000 m of cable in an ice sheet (scenario (iii) above), but penetration into glacier ice (scenarios (i) and (ii) above) could be realistic with the use of a currently employed generator. 相似文献
118.
The spring diatom bloom characterizes the plankton and nutrient dynamics in the Oyashio region, the westernmost part of the subarctic Pacific. Previous studies have shown that NO3 was not depleted during the spring bloom, and an increase in the consumption ratio of Si(OH)4 to NO3 (ΔSi(OH)4:ΔNO3) was observed as the spring bloom progressed. The increase in ΔSi(OH)4:ΔNO3 has been suggested to be caused by growth stresses of diatoms, e.g. light limitation by self-shading. In the present study, incubation experiments of sea-surface water from the Oyashio region under saturated irradiance showed that NO3 was depleted first and ΔSi(OH)4:ΔNO3 was more or less constant until the NO3 depletion occurred. The increase in ΔSi(OH)4:ΔNO3 was observed after the NO3 depletion had occurred in contrast with the field observation. This result of the increase in ΔSi(OH)4:ΔNO3 under saturated irradiance after NO3 depletion suggests that the in situ increase in ΔSi(OH)4:ΔNO3 before the NO3 depletion might be caused by light limitation for diatoms. Responses to a reduction in irradiance were examined using diatom species isolated from the Oyashio region. Variable responses to a reduced irradiance were observed for cell specific C, N, Si and chlorophyll a (Chl) contents. However, the examined diatom species showed similar tendencies for increases in Si:C and Si:N and decreases in C:Chl ratios with the reduction in irradiance. We conclude that light limitation changes the uptake ratio of nutrients and the elemental composition of diatoms and that light limitation is one of the factors influencing the physiology of diatoms and nutrient dynamics in the Oyashio region during the spring bloom. 相似文献
119.
Victor Vladimirovich Orlov Anna V. Petrova Kiyotaka Tanikawa Masaya M. Saito Alija I. Martynova 《Celestial Mechanics and Dynamical Astronomy》2008,100(2):93-120
The rectilinear equal-mass and unequal-mass three-body problems are considered. The first part of the paper is a review that
covers the following items: regularization of the equations of motion, integrable cases, triple collisions and their vicinities,
escapes, periodic orbits and their stability, chaos and regularity of motions. The second part contains the results of our
numerical simulations in this problem. A classification of orbits in correspondence with the following evolution scenarios
is suggested: ejections, escapes, conditional escapes (long ejections), periodic orbits, quasi-stable long-lived systems in
the vicinity of stable periodic orbits, and triple collisions. Homothetic solutions ending by triple collisions and their
dependence on initial parameters are found. We study how the ejection length changes in response to the variation of the triple
approach parameters. Regions of initial conditions are outlined in which escapes occur after a definite number of triple approaches
or a definite time. In the vicinity of a stable Schubart periodic orbit, we reveal a region of initial parameters that corresponds
to trajectories with finite motions. The regular and chaotic structure of the manifold of orbits is mostly defined by this
periodic orbit. We have studied the phase space structure via Poincaré sections. Using these sections and symbolic dynamics,
we study the fine structure of the region of initial conditions, in particular the chaotic scattering region. 相似文献
120.
Sayaka Sogawa Hiroya Sugisaki Hiroaki Saito Yuji Okazaki Shinji Shimode Tomohiko Kikuchi 《Journal of Oceanography》2013,69(1):71-85
The relationship between euphausiid community structure and water region was studied during a 2-year seasonal survey in the northwestern (NW) Pacific Ocean. The euphausiid community structure and its associated species were analyzed from 38 micronekton samples collected during eight cruises. The euphausiid community structure and its distribution patterns clearly corresponded to physical oceanographic features in the Oyashio region, Oyashio–Kuroshio Mixed Water Region (OKMWR), and Kuroshio region. In contrast, community structure was unrelated to seasonality. The 19 species out of 40 identified in this area were grouped and named after their habitats. The six cold-water species were grouped into three regional types: two coastal Oyashio species, three Oyashio–OKMWR species, and one Oyashio–Kuroshio species. The four species dominating in the OKMWR were categorized into each specific types: Nematoscelis difficilis as OKMWR–Oyashio species, Euphausia gibboides as OKMWR species, Euphausia similis as OKMWR–Oyashio & OKMWR–Kuroshio species, and Euphausia recurva as OKMWR–Kuroshio species. The seven warm-water species were categorized as Kuroshio–OKMWR species or Kuroshio species. The other two species were categorized as cosmopolitan species. In particular, regarding the result in the OKMWR, our study suggest that (1) the OKMWR has high species diversity, and (2) the dominant species, such as Euphausia pacifica, N. difficilis, E. similis, and E. gibboides, are considered to be key species in the food webs in this region. 相似文献