Earthquake resistant design of offshore building structures     

Ozaki  M. Hayashi  S. 《Oceanic Engineering, IEEE Journal of》1978,3(4):152-162

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Origin of the Moon — Capture by gas drag of the Earth's primordial atmosphere     

Kiyoshi Nakazawa  Teruyoshi Komuro  Chushiro Hayashi 《Earth, Moon, and Planets》1983,28(3):311-327

We propose a new scenario of the lunar origin, which is a natural extension of planetary formation processes studied so far by us in Kyoto. According to these studies, the Earth grew up in a gaseous solar nebula and, consequently, the sphere of its gravitational influence (i.e., the Hill sphere of the Earth) was filled by a gas forming a dense primordial atmosphere of the Earth. In the later stages, this atmosphere as well as the solar nebula was dissipated gradually, owing to strong activities of the early-Sun in a T Tauri-stage.In the present and the subsequent papers, we study a series of dynamical processes where a lowenergy (i.e., slightly unbound) planetisimal is trapped within the terrestrial Hill sphere, under the above-mentioned circumstances that the gas density of the primordial atmosphere is gradually decreasing. It is clear that two conditions must be satisfied for the lunar origin: first, an unbound planetesimal entering the Hill sphere have to dissipate its kinetic energy and come into a bound orbit before it escapes from the Hill sphere and, second, the bound planetisimal never falls onto the surface of the Earth.In this paper we study the first condition by calculating the oribital motion of a planetesimal in the Hill sphere, which is affected both by solar gravity and by atmospheric gas drag. The results show that a low-energy planetisimal with the lunar mass or less can be trapped in the Hill sphere with a high probability, if it enters the Hill sphere at stages before the atmospheric density is decreased to about 1/50 of the initial value.In the subsequent paper, the second condition will be studied and it will be shown that a tidal force, among other forces, is very important for a trapped planetesimal to avoid collision with the Earth and stay eternally in the Hill sphere as a satellite.  相似文献   

Gust and downward momentum transport in the atmospheric surface layer     

Taiichi Hayashi 《Boundary-Layer Meteorology》1992,58(1-2):33-49

The intermittent structure of the turbulent wind field in the atmospheric surface layer is investigated by conditional sampling methods. The results show that downward momentum can be transported efficiently during a peak gust. The horizontal structure of the gust is also revealed by observing the spatial structure of wind speed fluctuations from a network of 28 anemometers. The high wind region consists of a gust front with a sudden increase of wind speed at the front and a slow decrease to its rear. The development of the gust front is related closely to the momentum flux during the short time of passage of the gust.  相似文献   

A Late Cretaceous-Paleogene cauldron cluster: the Nôhi Rhyolite,central Japan     

Yoshimitsu Koido 《Bulletin of Volcanology》1991,53(2):132-146

The Nôhi Rhyolite now occupies an area of about 5000 km² in central Japan. It is the largest cluster of volcanic piles of Late Cretaceous to Paleogene age on the Inner Side of SW Japan. It unconformably overlies Paleozoic to Jurassic rocks and is intruded by Paleogene granitic intrusions in its southern and northern parts. The Nôhi Rhyolite consists chiefly of rhyolitic to rhyodacitic welded-tuff sheets with subordinate amounts of volcaniclastic sedimentary rocks. Each welded-tuff sheet is usually 200 to 700 m thick, extends laterally 20 to 60 km, and is composed of nearly homogeneous densely welded tuff. Six volcanic sequences (I–VI) are recognized in the southern and central parts of the Nôhi Rhyolite. Each sequence generally comprises successive accumulations of welded-tuff sheets and volcaniclastic sedimentary layers underlying the sheets. Sequence I, III and V volcanism was derived from zoned magma bodies and was accompanied by granodiorite porphyries. Sequence II, IV and probably VI volcanism was derived from homogeneous magma bodies and was not accompanied by granodiorite porphyries. The estimated total volume is of the order of 300–700 km³ for Sequences I, II and IV, 1600 km³ for Sequence III, and 50 km³ or less for Sequences V and VI. The volume of Sequence III is one of the largest volumes of ashflow tuffs so far recognized. One or more polygonal cauldrons, each 15–40 km across and 400–1000 m deep, formed during each of Sequence I through IV. These cauldrons were generally formed by two successive depressions. The first depression in each sequence is of the Motojuku-type, characterized by collapse prior to the principal eruption. The second depression was formed during the principal eruption. The cauldron of Sequence V has an unusual shape and was probably formed during or after the eruption. The development of a cauldron in Sequence VI is uncertain. The Nôhi Rhyolite is elongate in a NW direction and contains a cluster of seven or eight cauldrons. These cauldrons formed in a tension field trending N and NE, and their volcanism migrated northward. The main regional tectonic framework controlling the cauldrons resulted from uplifting of the basement, which is ascribed to the ascent of a large volume of magma in Late Cretaceous to early Paleogene time.  相似文献   

Variation of chemical compositions in volcanic gases and water at Kusatsu-Shirane Volcano and its activity in 1976     

J. Ossaka  T. Ozawa  T. Nomara  T. Ossaka  J. Hirabayashi  A. Takaesu  T. Hayashi 《Bulletin of Volcanology》1980,43(1):207-216

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Improved techniques for studies of mass balances and fractionations among families of metals within terrestrial ecosystems     

Robert W Elias  Todd K Hinkley  Yoshimitsu Hirao  Clair C Patterson 《Geochimica et cosmochimica acta》1976,40(6):583-587

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Effects of ground water exchange on the hydrology and ecology of surface water   总被引：11，自引：0，他引：11  

Hayashi M  Rosenberry DO 《Ground water》2002,40(3):309-316

Ground water exchange affects the ecology of surface water by sustaining stream base flow and moderating water-level fluctuations of ground water-fed lakes. It also provides stable-temperature habitats and supplies nutrients and inorganic ions. Ground water input of nutrients can even determine the trophic status of lakes and the distribution of macrophytes. In streams the mixing of ground water and surface water in shallow channel and bankside sediments creates a unique environment called the hyporheic zone, an important component of the lotic ecosystem. Localized areas of high ground water discharge in streams provide thermal refugia for fish. Ground water also provides moisture to riparian vegetation, which in turn supplies organic matter to streams and enhances bank resistance to erosion. As hydrologists and ecologists interact to understand the impact of ground water on aquatic ecology, a new research field called "ecohydrology" is emerging.  相似文献   

Expansion of the Nishinomiya Built Environment Database     

Kohiyama  Masayuki  Yamashita  Norihiko  Sato  Tadanobu  Hengjian  Lu  Maki  Norio  Tanaka  Satoshi  Hayashi  Haruo 《Natural Hazards》2003,29(3):501-522

The Nishinomiya Built Environment Database, which can be used to analyze the disaster process of the 1995 Hanshin-Awaji Earthquake Disaster in Nishinomiya City, has been expanded with new data entries. The database contains the following very detailed datasets: (1) the urbanization area base map, (2) casualty data, (3) three sets of building damage data surveyed by the Nishinomiya City, the Architectural Institute of Japan and the City Planning Institute of Japan, and the Kobe University, (4) building property data based on the real estate tax roll, (5) photographs of the damaged buildings with the information on the place and orientation of the picture, and (6) the estimated distribution of the seismic ground motion. The seismic ground motion was simulated for the southern part of Nishinomiya City and two verification sites in Kobe City and Amagasaki City. In the simulation, the borehole data of public facilities were used to model the surface soils as one-dimensional layers, taking into consideration the fact that the spatial distribution of the sediment/basement interface forms a slope. The model of the fault rupture process simulated the characteristics of the seismic motion at basement level, and amplification effects of the surface layers were evaluated based on multiple reflection theory. The distribution of peak ground acceleration and peak ground velocity was estimated from acceleration response spectra at each borehole point. In addition, the relationship between simulated seismic ground motion and building damage was studied based on newly proposed band-passed spectrum intensity using the expanded database. This confirmed that detailed categorization is necessary in order to evaluate the fragility functions, especially for reinforced concrete structures. The database should provide fundamental information for identifying the relationship between the ground motions and the extent and pattern of building damage, or the pattern of the occurrence of casualties.Presently  相似文献   

Effective time-domain soil-structure interaction analysis based on FFT algorithm with causality condition     

Yasuhiro Hayashi  Hiroshi Katukura 《地震工程与结构动力学》1990,19(5):693-708

We propose an effective and reliable time-domain substructure technique which takes soil-structure interaction effects into account and uses the flexibility coefficients of unbounded soil obtained in the frequency domain. Compared with previous methods, the frequency points to calculate flexibility coefficients, and computational loads in the calculation of time-domain interaction forces, are reduced. In the formulation, we have assumed the flexibility coefficient to be a periodic function, obtained within the bandlimited frequency range, which also includes the predominant frequencies of the structure and incident wave. Then we simulate the periodic flexibility coefficients using discrete impulse responses in the time-domain analyses. However, the real and imaginary parts of the bandlimited flexibility coefficients do not form a Hilbert transform pair; the discrete impulse responses should be modified to be causal for the time-domain analyses. We present various discrete impulse responses which have been obtained from only the real part, only the imaginary part and from both the real and imaginary parts of the frequency-domain flexibility coefficients by FFT with causality conditions. Through a numerical example the relationship between the modified discrete impulse responses and the validity of the time-domain substructure method is presented.  相似文献   

Geology, Wall-rock Alteration and Vein Paragenesis of the Bilimoia Gold Deposit, Kainantu Metallogenic Region, Papua New Guinea     

Joseph Onglo Espi    Ken-Ichiro Hayashi    Kosei Komuro    Hiroyasu Murakami  Yoshimichi Kajiwara 《Resource Geology》2007,57(3):249-268

The Bilimoia deposit (2.23 Mt, 24 g/t Au), located in the eastern Central Mobile Belt of mainland Papua New Guinea, is composed of fault‐hosted, NW–NNW‐trending Irumafimpa–Kora and Judd–Upper Kora Au‐quartz veins hosted by Middle–Late Triassic basement that was metamorphosed to medium‐grade greenschist facies between Middle–Late Triassic and Early–Middle Jurassic. Mineralizing fluids were introduced during crustal thickening, rapid uplift, change of plate motions from oblique to orthogonal compression, active faulting and S₃ and S₄ events in an S₁–S₄ deformation sequence. The Bilimoia deposit is spatially and temporally related to I‐type, early intermediate to felsic and late mafic intrusions emplaced in Late Miocene (9–7 Ma). Hydrothermal alteration and associated mineralization is divided into 10 main paragenetic stages: (1) chlorite–epidote‐selvaged quartz–calcite–specularite vein; (2) local quartz–illite–pyrite alteration; (3) quartz–sericite–mariposite–fuchsite–pyrite wall‐rock alteration that delimits the bounding shears; (4) finely banded, colloform‐, crustiform‐ and cockade‐textured and drusy quartz ± early wolframite ± late adularia; (5) hematite; (6) pyrite; (7) quartz ± amethyst‐base metal sulfides; (8) quartz–chalcopyrite–bornite–Sn and Cu sulfides–Au tellurides and Te ± Bi ± Ag ± Cu ± Pb phases; (9) Fe ± Mn carbonates; and (10) supergene overprint. Fluid inclusions in stage 4 are characterized by low salinity (0.9–5.4 wt% NaCl equivalent), aqueous–carbonic fluids with total homogenization temperatures ranging from 210 to 330°C. Some of the inclusions that homogenized between 285 and 330°C host coexisting liquid‐ and vapor‐rich (including carbonic) phases, suggesting phase separation. Fluid inclusions in quartz intergrown with wolframite have low salinity (0.9–1.2 wt% NaCl equivalent), aqueous–carbonic fluids at 240–260°C, defining the latter’s depositional conditions. The ore fluids were derived from oxidized magmatic source initially contaminated by reduced basement rocks. Wall‐rock alteration and involvement of circulating meteoric waters were dominant during the first three stages and early part of stage 4. Stage 5 hematite was deposited as a result of stage 4 phase separation or entrainment of oxygenated groundwater. Gold is associated with Te‐ and Bi‐bearing minerals and mostly precipitated as gold‐tellurides during stage 8. Gold deposition occurred below 350°C due to a change in the sulfidation and oxidation state of the fluids, depressurization and decreasing temperature and activities of sulfur and tellurium. Bisulfides are considered to be the main Au‐transporting complexes. The Bilimoia deposit has affinities that are similar to many gold systems termed epizonal orogenic and intrusion‐related. The current data allow us to classify the Bilimoia deposit as a fault‐controlled, metamorphic‐hosted, intrusion‐related mesothermal to low sulfidation epithermal quartz–Au–Te–Bi vein system.  相似文献