Seismic response controlled structure with Active Variable Stiffness system     

Takuji Kobori  Motoichi Takahashi  Tadashi Nasu  Naoki Niwa  Katsura Ogasawara 《地震工程与结构动力学》1993,22(11):925-941

The Active Variable Stiffness (AVS) system is proposed as a seismic response control system. It actively controls structural characteristics, such as stiffness of a building, to establish a non-resonant state against earthquake excitations, thus suppressing the building's response. It consumes a relatively small amount of energy and maintains the safety of the building in moderate to severe earthquakes. In order to accumulate practical data and investigate them, a building has been constructed as a trial. This paper describes the applied system, the control algorithm, verification of stiffness selection, results of tests for verifying system characteristics, some observed earthquake records and simulation analyses. Responses in controlled and uncontrolled states have been compared to show the effectiveness of the proposed system.  相似文献   

An evaluation of the apparent dissociation constants of carbonic acid in seawater     

Taro Takahashi  Peter Kaiteris  Wallace S. Broecker  Arnold E. Bainbridge 《Earth and Planetary Science Letters》1976,32(2):458-467

The internal consistency of five sets of apparent dissociation constants of carbonic acid in seawater obtained by Buch (1951), Lyman (1956), Edmond and Gieskes (1970), Hansson (1973) and Mehrbach et al. (1973) have been tested using the GEOSECS Atlantic data for the total alkalinity, the total CO₂ concentration and the partial pressure of CO₂. As a measure of the consistency for each of the five sets of the dissociation constants with the data, the 77 measured values of the partial pressure of CO₂ have been compared with those calculated from the alkalinity and total CO₂ values determined for these samples. It has been found that: (1) the apparent dissociation constants of Lyman (1956), Hansson (1973) and Mehrbach et al. (1973) appear to be internally consistent with the data, whereas those of Buch (1951) and of Edmond and Gieskes (1970) appear to be markedly inconsistent with the GEOSECS data; and (2) on the basis of a statistical analysis of the data grouped in three temperature ranges, the dissociation constants of Lyman (1956) and of Mehrbach et al. (1973) appear to be most satisfactory.  相似文献   

Thermal history of iherzolite xenoliths—I. Petrology of iherzolite xenoliths from the ichinomegata crater,oga peninsula,northeast Japan     

Eiichi Takahashi 《Geochimica et cosmochimica acta》1980,44(11):1643-1658

The thermal history of four spinel lherzolites (Lhz-13. Lhz-28, Lhz-29 and Lhz-53) from tuff breccia of the Ichinomegata crater, northeast Japan, has been studied in detail. Lhz-13 and Lhz-53 showed nearly perfect chemical homogeneity of the constituent minerals, and increase of Ca near the rim of olivine is the only disequilibrium evidence observed. In addition to the Ca zoning in olivine, Lhz-28 and Lhz-29 revealed compositional zoning in the Mg/Mg + Fe ratio and Ca content in ortho- and clinopyroxenes. Lhz-13 and Lhz-53 equilibrated at about 800°C in the upper mantle, based on Fe/Mg partitioning between olivine/spinel and olivine/clinopyroxene, and on the mutual solubility of Ca between olivine and pyroxenes. Lhz-28 and Lhz-29 also equilibrated originally at about 800°C, but were preheated at about 1000°C prior to their entrapment by the ascending host magma. The Fe/Mg partitioning between olivine /spinel and olivine/clinopyroxene reequilibrated during the preheating event: however, the Ca solubility did not reequilibrate. Olivine alone has rehomogenized with a high-Ca content but pyroxenes were compositionally zoned with Ca. The preheating event, indicated by the high-Ca content in the core of olivine, is recognized from about a half of the Ichinomegata Iherzolites (50 xenoliths were studied).The duration of heating during the transport of the xenolith by the magma (estimated from the width of the Ca zoning in the rim of olivine) ranges between several hours to a year depending on the rock specimen. From the requirement to reset olivine core compositions, the duration of the preheating event was estimated as greater than 1000 yr.  相似文献   

Isotopic anomalies of noble gases in meteorites and their origins—VII. C3V carbonaceous chondrites     

Jun-Ichi Matsuda  Roy S. Lewis  Hiroshi Takahashi  Edward Anders 《Geochimica et cosmochimica acta》1980,44(11):1861-1874

Noble gases were measured in bulk samples of the C3V chondrites Grosnaja, Vigarano, and Leoville, and in HF,HCl-insoluble residues before and after etching with HNO₃. The residues were characterized by INAA and SEM. Gas components were determined, directly or by subtraction, for the following fractions: HF,HCl-solubles (?98% of the meteorite), ‘sphase Q’, a poorly characterized trace mineral that is insoluble in HCl-HF but soluble in HNO₃, and an insoluble residue, consisting of ferrichromite, carbonaceous matter, and spinel.Bulk meteorites show some correlation of the noble-gas pattern with McSween's subclasses: two ‘oxidized’ C3V's—Allende (LEWIS et al, 1975) and Grosnaja— have lower Ar/Xe but higher Ne/Xe ratios than the ‘reduced’ C3V's—Vigarano and Leoville—which are transitional to LL3's and C3O chondrites in both respects. An HCl-soluble mineral of high Ar/Xr ratio seems to be responsible. In other respects, the 3 C3V's of this study resemble Allende, with only moderate differences. Phase Q contains most of the Ar, Kr, Xe, but only small amounts of Ne; the etched residues contain planetary Ne ($\text{Ne}{}^{20}\text{Ne}{}^{22}\text{? 8.5}$) and the controversial CCFXe component, enriched in the heavy Xe isotopes ($\text{Xe136}\text{Xe132 ? 0.4–0.5}$). The CCFXe is accompanied by an ‘L-Xe’ component that is enriched in the light Xe isotopes. The proportion of the two is virtually constant in C3V's. as in all other C-chondrites. in contrast to the ~ 2-fold variation in ordinary chondrites.C3V's have systematically higher $\text{Xe}{}^{136}\text{Xe}{}^{132}$ ratios, and hence higher ratios of CCFXe to planetary Xe, than do other chondrite classes. This may reflect some peculiarity in their formation conditions, favoring uptake of CCFXe.  相似文献   

A strategy for the use of bomb-produced radiocarbon as a tracer for the transport of fossil fuel CO₂ into the deep-sea source regions     

Wallace S. Broecker  Tsung Hung Peng  Taro Takahashi 《Earth and Planetary Science Letters》1980,49(2):463-468

Because the equilibration time for CO₂ gas between the surface ocean and atmosphere is an order of magnitude shorter than the equilibration time for the isotopes of carbon, bomb-produced radiocarbon cannot be simply used as a tracer for fossil fuel CO₂. This difference is especially important for the areas of deep water formation. In this paper we derive the relationship between the isotopic equilibration time and chemical equilibration times for carbon between sea and air. We also show that if the distribution of a second transient tracer is measured, it is possible to circumvent the ambiguity associated with this exchange time difference. Tritium, while adequate in purely diffusive models, is not ideal as the second transient in models involving advection (i.e., downwelling). For such models⁸⁵Kr or freon is a much better choice.  相似文献   

Ries impact crater,southern Germany: search for meteoritic material     

John W. Morgan  Marie-josée Janssens  Jan Hertogen  Jacques Gros  Hiroshi Takahashi 《Geochimica et cosmochimica acta》1979,43(6):803-815

Twenty-three samples from the Ries crater, representing a wide range of shock metamorphism, were analyzed for seven siderophile elements (Au, Ge, Ir, Ni, Os, Pd, Re) and five volatile elements (Ag, Cd, Sb, Se, Zn). Taking Ir as an example, we found siderophile enrichments over the indigenous level of 0.015 ppb Ir occur in only eight samples. The excess is very modest; even the most enriched samples (a weakly shocked biotite gneiss and a metal-impregnated amphibolite) have Ir, Os corresponding to ~4 × 10^?4 C1 chondrite abundances. Of five flädle glasses analyzed only one shows excess Ir. Suevite matrix and vesicular glass have slight enrichment, but homogenous glass from the same rock does not. In flädle glasses, Ni and Se are strongly correlated and apparently reside in Ir, Os-poor Sulfides [pyrrhotite, chalcopyrite, pentlandite(?)]of terrestrial, probably sedimentary, origin. The Ir, Os and Ni enrichments of the metal-bearing amphibolite are compatible with chondritic ratios, but these are ill-defined because of uncertainty in Ni. In the other samples enriched in siderophiles Ir(Os), Ni and Se are mutually correlated; $\text{Ni}\text{Ir}$ and $\text{Ni}\text{Os}$ ~ 11 × C1 and are much higher than any chondritic ratios; $\text{Se}\text{Ni}\text{~ 2 × C1}$ and suggests a sulfide phase, rather than metal may be the host of the correlated elements. Lacking a plausible local source, this material is apparently meteoritic in origin. The unusual elemental ratios, coupled with the very low enrichments, tend to exclude chondrites and most irons as likely projectile material. Of the achondrites, aubrites seem slightly preferable. Ratios of excess siderophiles in Ries materiel match tolerably those of an aubrite (possibly atypical) occurring as an inclusion in the Bencubbin meteorite, Australia. The Hungaria group of Mars-crossing asteroids may be a source of aubritic projectiles.  相似文献   

Petrologic model of the crust and upper mantle of the Japanese Island arcs     

E. Takahashi 《Bulletin of Volcanology》1978,41(4):529-547

Mafic and ultramafic xenoliths, in the Holocene calc-alkali andesite of Ichinomegata(1) crater in Oga peninsula and those in the Plio-Pleistocene alkali-olivine basalts of Oki-Dōgo island in the Japan Sea, have been studied in detail. Based on geothermometry and geobarometry, and relative abundance of the rock types of the xenoliths, petrologic models of the crust and upper mantle beneath these two areas were constructed. The crust and upper mantle beneath Ichinomegata crater are characterized by hydrous and relatively low temperature conditions. On the other hand, the crust and upper mantle beneath Oki-Dōgo island are characterized by nearly anhydrous and high temperature conditions, and presence of thick lavers of peridotite and pvroxenite cumulates in the uppermost mantle. The crust and upper mantle of the western part of the Northeast Honshū Arc can be considered as similar to those beneath Ichinomegata crater, because of the common occurrence of similar mafic xenoliths from many andesite volcanoes in this area. The crust and upper mantle of the northern part of the Southwest Honshū Arc, in the same way, can be regarded as similar to those beneath Oki-Dōgo island. Differences in amount of hydrous minerals of deep-seated rocks between the two areas can be interpreted as due to the presence of migrating water derived from the subducting Pacific plate in the Northeast Honshū Arc. Difference in slope of the geotherm may be due to the difference in temperature of the partial melt zones beneath these two areas. Bulk chemical compositions of the lower crustal materials of the Japanese island arcs, 85 mafic inclusions from 15 volcanoes, are listed, and it is concluded that they are cumulates or metamorphosed cumulates in the lower crust.  相似文献   

Melting kinetics of a plagioclase feldspar     

Akira Tsuchiyama  Eiichi Takahashi 《Contributions to Mineralogy and Petrology》1983,84(4):345-354

Partial melting experiments on plagioclase feldspar have been carried out to investigate textures and kinetics of the melting. A labradorite single crystal was heated at one atmosphere pressure and temperatures within its melting interval as a function of time. So called honeycomb, fingerprint, or sieve textures were produced except for the runs just below the liquidus. The melting was initiated by heterogeneous nucleation of melt at the surface and/or interior (cracks and possively dislocations) of the crystal. The pattern of the melt is dendritic with a few μm arm spacing. After the melt develops throughout the crystal, the volumes of melt and residual crystal become larger and smaller, respectively, without changing the arm spacings. The melt is homogeneous and has the approximate temperature dependent liquidus composition irrespective of the time. There are compositional gradients in the residual crystal after short periods of melting. The An content of the crystals increases with increasing time until it finally reaches equilibrium with the melt after several thousands minutes of heating. It is concluded that the enlargement of the melt, the main process of the melting, is controlled by diffusion in the crystal. The fact that partial melts have the composition of the equilibrium liquidus even from the first several minutes strongly suggests that the local equilibrium at the crystal-liquid interface is satisfied during the melting. Some of the honeycomb, fingerprint, and sieve textures found in xenoliths and phenocrysts of sodic plagioclase in volcanic rocks would be caused by heating events (such as magma mixing) during which temperatures of magmas were temporarily higher than the solidus of some of the minerals.  相似文献   

Recycling of suspended particulates by the interaction of sea-land breeze circulation and complex coastal terrain     

H. Choi  Y. H. Zhang  S. Takahashi 《Meteorology and Atmospheric Physics》2004,87(1-3):109-120

Summary The dispersion of recycled particulates in the complex coastal terrain surrounding Kangnung city, Korea was investigated using a three-dimensional non-hydrostatic numerical model and lagrangian particle model (or random walk model). The results show that particulates at the surface of the city that float to the top of thermal internal boundary layer (TIBL) are then transported along the eastern slope of the mountains with the sea breeze passage and nearly reach the top of the mountains. Those particulates then disperse eastward at this upper level over the coastal sea and finally spread out over the open sea. Total suspended particulate (TSP) concentration near the surface of Kangnung city is very low. At night, synoptic scale westerly winds intensify due to the combined effect of the synoptic scale wind and land breeze descending the eastern slope of the mountains toward the coast and further seaward. This increase in speed causes development of internal gravity waves and a hydraulic jump up to a height of about 1km above the surface over the city. Particulate matter near the top of the mountains also descends the eastern slope of the mountains during the day, reaching the central city area and merges near the surface inside the nocturnal surface inversion layer (NSIL) with a maximum ground level concentration of TSP occurring at 0300 LST. Some particulates are dispersed following the propagation area of internal gravity waves and others in the NSIL are transported eastward to the coastal sea surface, aided by the land breeze. The following morning, particulates dispersed over the coastal sea from the previous night, tend to return to the coastal city of Kangnung with the sea breeze, developing a recycling process and combine with emitted surface particulates during the morning. These processes result in much higher TSP concentration. In the late morning, those particulates float to the top of the TIBL by the intrusion of the sea breeze and the ground level TSP concentration in the city subsequently decreases.  相似文献   

Thermal equation of state of majorite with MORB composition     

Yu Nishihara  Ichiro Aoki  Eiichi Takahashi  Ken-ichi Funakoshi 《Physics of the Earth and Planetary Interiors》2005,148(1):73-84

In situ synchrotron X-ray diffraction experiments were conducted using the SPEED-1500 multi-anvil press at SPring-8 on majoritic garnet synthesized from natural mid-ocean ridge basalt (MORB), whose chemical composition is close to the average of oceanic crust, at 19 GPa and 2200 K. Pressure-volume-temperature data were collected using a newly developed high-pressure cell assembly to 21 GPa and 1273 K. Data were fit to the high-temperature Birch-Murnaghan equation of state, with fixed values for the ambient cell volume (V₀ = 1574.14(4) Å³) and the pressure derivative of the isothermal bulk modulus (K^′T = 4). This yielded an isothermal bulk modulus of K_T0 = 173(1) GPa, a temperature derivative of the bulk modulus (∂K_T/∂T)_P = −0.022(5) GPa K⁻¹, and a volumetric coefficient of thermal expansivity α = a + bT with values of a = 2.0(3) × 10⁻⁵ K⁻¹ and b = 1.0(5) × 10⁻⁸ K⁻². The derived thermoelastic parameters are very similar to those of pyrope. The density of subducted oceanic crust compared to pyrolitic mantle at the conditions in Earth's transition zone (410-660 km depth) was calculated using these results and previously reported thermoelastic parameters for MORB and pyrolite mineral assembledges. These calculations show that oceanic crust is denser than pyrolitic mantle throughout the mantle transition zone along a normal geotherm, and the density difference is insensitive to temperature at the pressures in lower part of the transition zone.  相似文献