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排序方式: 共有37条查询结果,搜索用时 15 毫秒
1.
Tadao Minami 《地震工程与结构动力学》1987,15(6):697-709
Earthquake observations and microtremor measurements were conducted on a 12-storey steel-reinforced concrete building just after its completion. Marked stiffness deterioration was observed over the following five-year period, during which time several earthquakes were recorded and two additional series of microtremor measurements were made. The large contribution made by non-structural elements (especially the curtain walls that cover all sides of the building) to the apparent stiffness of the entire building was lost during this period. Both ageing effects and stiffness reductions depend greatly on the amplitude of the structural response of this building. 相似文献
2.
Tadao Nishiyama Hibiki Eguchi Dai Shiosaki Akira Yoshiasa Nobutatsu Mochizuki Yasushi Mori Kazumasa Sugiyama Hiroshi Arima Kunio Yubuta 《Island Arc》2021,30(1):e12382
Spinifex-like textured metaperidotites from the Higo Metamorphic Rocks (HMR), west-central Kyushu, Japan, may be formed by high-pressure dehydration of antigorite, and may indicate deep subduction of serpentinite reaching a pressure–temperature condition of 1.6 GPa and 740–750 °C. Three rock types have been identified based on mineral assemblage and rock texture: Type I (L) consisting of medium-grained (1–5 cm long) olivine + enstatite + chromite ±tremolite with secondary talc and anthophyllite that occurs in low-grade metamorphic rocks of the biotite zone, Type I (H) of coarse-grained (up to 10 cm long) olivine + enstatite (with clinoenstatite lamella) + chromite ±tremolite with secondary talc that occurs in high-grade metamorphic rocks of the garnet-cordierite zone, and Type II composed of Al-spinel + chlorite + olivine + apatite + ilmenite with minor sodic gedrite in the garnet-cordierite zone together with Type I (H). Olivines in all rock types are mostly serpentinized during exhumation. The chromite-olivine thermometer gives 560–690 °C for Type I (L) rocks, and the spinel-olivine thermometer gives 610–740 °C for Type II rocks. The peak metamorphic pressure will be higher than 1.6 GPa based on the location of the experimentally determined invariant point (P = 1.6 GPa and T = 670 °C) of antigorite + forsterite + enstatite + talc + H2O. This estimate is consistent with the occurrence of chlorite in Type II rocks, which is stable up to 890 °C at 2.0 GPa. The spinifex-like textured metaperidotites occur as small bodies in the low P/T type gneisses, implying tectonic juxtaposition of them probably during exhumation of the HMR. Recent findings of medium pressure (0.9–1.2 GPa) granulites and gneisses from the HMR may indicate that the HMR has a deep root into the wedge mantle from which the spinifex-like textured metaperidotites have derived. 相似文献
3.
Tadao Mitsui 《Earth, Moon, and Planets》2006,99(1-4):265-273
As a possible design of a future geoneutrino detector, a KamLAND-type, monolithic, liquid scintillator detector with a thicker
veto and a method for particle identification to reject neutron and 9Li background from cosmic-ray muon spallation is considered. Assuming such a detector, the possibility for geoneutrino observation
at a depth of around 300 meters of water equivalent is investigated. 相似文献
4.
Kunihiro T Miyazaki T Uramoto Y Kinoshita K Inoue A Tamaki S Hama D Tsutsumi H Ohwada K 《Marine pollution bulletin》2008,57(1-5):68-77
We monitored seasonal changes of the abundance and composition of microorganisms in the fish-farm sediment in Kusuura Bay, Amakusa, Japan, using the quinone profiling technique, during bioremediation by introducing cultured colonies of polychaete, Capitella sp. I. In November 2004, approximately 9.2 million cultured worms were transferred to the fish-farm sediment, which increased rapidly, and reached 458.5 gWW/m(2) (528,000 indiv./m(2)) in March 2005. During this fast-increasing period of Capitella, the microbial quinone content of the surface sediment (0-2 cm) also increased markedly, and reached 237 micromol/m(2) in January 2005, although the water temperature decreased to the lowest levels in the year. Particularly, the mole fraction of ubiquinone-10 in total quinones in the sediment, indicating the presence of alpha subclass of Proteobacteria, increased by 9.3%. These facts suggest that the bacterial growth was enhanced markedly by the biological activities of worms in the sediment, and the bacteria played an important role in the decomposition of the organic matter in the sediment. 相似文献
5.
Abstract We carried out hydrothermal experiments in the system dolomite‐quartz‐H2O to track the temporal change in reaction rates of simultaneous reactions during the development of reaction zones. Two types of configurations for the starting materials were prepared: dolomite single crystals + quartz powder + water and quartz single crystals + dolomite powder + water, both sealed separately in gold capsules. Runs at 0.1GPa and 600°C with cold seal pressure vessels gave the following results. (i) In short duration (45–71 h) runs metastable layer sequences involving wollastonite and talc occur in the reaction zone, whereas they disappear in longer duration (168–336 h) runs. (ii) The layer sequence of the reaction zones in short duration runs differs from place to place on the dolomite crystal even in the same run. (iii) The diversity of layer sequences in the short duration runs merges into a unique layer sequence in the longer duration runs. (iv) The reaction zone develops locally on the dolomite crystal, but no reaction zone was observed on the quartz crystal in any of the runs. The lines of evidence (i)–(iii) show that the system evolves from an initial transient‐ to a steady‐state and that the kinetic effect is important in the development of reaction zones. A steady diffusion model for the unique layer sequence Qtz/Di/Fo + Cal/Dol + Cal/Dol shows that the Dol + Cal layer cannot be formed by diffusion‐controlled process and that the stability of the layer sequence Qtz/Di/Fo + Cal/Dol depends not only on L‐ratios (a = /LCaOCaO and b = /LMgOMgO) but also on the relative rate P = (−2ξ1 − ξ2)/(–ξ1 − 2ξ2) of competing reactions: Dol + 2Qtz = Di + 2CO2 (ξ1) and 2Dol + Qtz = Fo + 2Cal + 2CO2 (ξ2). For smaller P the stability field will shift to higher values of a and b. The steady diffusion model also shows that the apparent‐non‐reactivity on the quartz surface can be attributed to void formation in a large volume fraction in the diopside layer. 相似文献
6.
A series of measurements of winds and wind-waves were carried out in wind-wave flumes. A data analysis based on the hypothesis
of local equilibrium yielded a new empirical formula on the controversial quantity of roughness heightz
0 over the water surface:
, where the nondimensional roughness height
is defined bygz
0/u
*
2 and the wave-wind parameterũ byω
p
u
*/g, g being the gravitational acceleration,u
* the friction velocity of air,ω
p
the peak frequency of wind-wave spectra. The obtained formula is compared with Charnock's (1955) and Toba's (1979) proposals;
is constant in the former and inversely proportional toũ in the latter. As in Toba's, this formula immediately leads to a practically important conclusion that the drag coefficientC
d
depends not merely on the usual variableU
10 (wind velocity at 10m height over the water surface), but also on the surface state represented by wind-waves. An explicit
expression is provided for the drag coefficient incorporating the wave-wind parameter; it covers the range ofC
d
calculated from most of the previous drag formulas, by varying the wave-wind parameter. 相似文献
7.
Wind-wave spectra measured in a wind-flume are analyzed according to the hypothesis of local equilibrium. The gross relation between the wave height and the frequency is reexamined to yield the basic validity of the 3/2-power law of Toba orE~? in the range of 0.4≦?≦1, where? is the wave-wind parameter defined by?=ω p u */g; ω p denotes the peak frequency of the wind-wave spectra,u * the friction velocity andg the gravitational acceleration. Noticeable deviation is found, however, for?<0.4 or?>1. In particular, the data for large? suggest the existence of an upper limit of the wave nonlinearityE at about 5×10?2, whereE=Eω p 4 /g2 withE the total power of the wind wave spectrum. Then, the spectral form is investigated in detail. As? decreases, the normalized spectrum becomes more gradual as a whole, but its forward (low frequency) part tends to show a steeper profile. In the high frequency region ( \(\tilde \omega \) >2.6), the spectrum is found to have a functional form likeu * 2 ω ?3, which differs from the usualω-dependence asω ?5 orω ?4. It suggests weak dependence of the high-frequency spectra on the gravitational accelerationg and on the peak frequencyω p ; spectral density at high frequencies may be saturated, so that its magnitude may be dominated by the frequencyω, the friction velocityu *, the surface tension and the viscosity. 相似文献
8.
Water surface elevations(t), vertical surface velocities
and vertical surface acceleration
of wind-generated waves have been measured in a laboratory wind wave channel by using resistance-type wave gauges combined with an electronic differentiation circuits. Probability distributions of the values of(t),
, and
have been determined from the wave records.In an initial stage of wave generation,i.e., when wind waves are generated at short fetches and low wind speeds, the observed distributions for(t),
and
are appreciately good fit to the distributions given by successive sum of a Gram-Charlier series, which has been derived following the formulation ofLonguet-Higgins (1963), by taking the weakly nonlinear effect into account.However, when wind waves develop with increasing wind speeds and fetches, the observed distributions deviate gradually from the Gram-Charlier series. Particularly, the deviations are remarkable for the distribution of
.When the wind speed increases, the observed distributions of(t),
and
show the following characteristics: (i) the skewnesses of the distributions of(t) and
decrease slightly, (ii) the skewness of
changes, at some wind speed, from positive small values to relatively large negative values, (iii) the kurtosis of the distribution of(t) decreases slightly but that of
increases slightly and these characteristics seem to depend not so much on fetches, (iv) the kurtosis of the distribution of
increases rapidly. 相似文献
9.
Effects of structural walls on the elastic–plastic earthquake response of short- to medium-height reinforced concrete buildings were investigated. The analytical model consists of independent lumped mass systems representing walls and frames connected at each floor. The wall structure undergoes flexural as well as shear deformation and fails in shear at relatively small story drifts, the frames deforming only in shear. As a measure of structural damage, the ductility factor responses of frame structures were calculated for different combinations of base shear coefficients for the frames and walls. In buildings with relatively weak frames, the installation of structural walls did not improve the large plastic response of the frames up to the point where the walls were unfailed in shear and the ductility factors of the frame structure were suddenly reduced to a very small number. For relatively strong frames, however, the response displacements decreased gradually as the number of walls increased, whether or not the walls failed. Empirical formulas for the required base shear coefficients of the walls and frames which gave a target ductility factor response also were derived for two particular groups of accelerograms. These equations should be of practical use in designing frame-wall type buildings and in retrofitting damaged buildings. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
10.