Steel slit shear walls with double‐tapered links capable of condition assessment          下载免费PDF全文

Masahiro Kurata  Liusheng He  Masayoshi Nakashima 《地震工程与结构动力学》2015,44(8):1271-1287

The concept of using a hysteretic damper as a condition assessment device that functions immediately after a damaging earthquake is realized by making use of the residual out‐of‐plane deformation of links that are arranged in slit shear walls. According to the proposed inspection procedure, the maximum drift ratio experienced by the slit wall is estimated based on the number of torsionally deformed links whose dimensions are determined so that the links would exhibit notable torsional deformation at the target deformations. The adoption of a double‐tapered shape for the links enables us to significantly increase the amount of out‐of‐plane deformation. The relationship between the dimensions and the torsional deformation of the links is established using numerical simulations. The effectiveness of the proposed condition assessment scenario is verified by using a series of cyclic loading tests for individual links and groups of links. As a hysteretic damper, the strength and stiffness of the links predicted by design equations matched well with test results. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Laboratory measurements of ‘porosity‐free’ intrinsic Vp and Vs in an olivine gabbro of the Oman ophiolite: Implication for interpretation of the seismic structure of lower oceanic crust          下载免费PDF全文

Satoshi Saito  Masahiro Ishikawa  Makoto Arima  Yoshiyuki Tatsumi 《Island Arc》2015,24(2):131-144

In order to determine ‘porosity‐free’ intrinsic ultrasonic compressional (Vp) and shear wave (Vs) velocities and Vp/Vs of an olivine gabbro from the Oman ophiolite, we developed a new experimental system using a piston‐cylinder type high‐pressure apparatus. The new system allowed us to measure velocities at pressures ranging from 0.20 to 1.00 GPa and at temperatures up to 300°C for Vp and 400°C for Vs. At room temperature, the Vp and Vp/Vs increase rapidly with pressure up to 0.40 GPa, while between 0.45 and 1.00 GPa the increase is more gradual. The change in increasing rate is attributed to closure of porosity at pressures above 0.45 GPa. Based on the linear regression of data obtained at higher pressures (0.45–1.00 GPa) and extrapolation to the lower pressures, combined with temperature derivatives of velocities of the sample measured at 1.00 GPa, we determined the intrinsic Vp and Vs of the sample as a function of pressure (P, in GPa) and temperature (T, in °C). The intrinsic velocities can be expressed as Vp (km/s) = 7.004 + 0.096 × P ? 0.00015 × T, and Vs (km/s) = 3.827 + 0.007 × P ? 0.00008 × T. We evaluated the intrinsic Vp and Vs of the olivine gabbro at oceanic crustal conditions and compared them with a velocity depth‐profile of the borehole seismic observatory WP‐2 area in the northwestern Pacific Basin. Although the intrinsic Vp (～7.0 km/s) and Vs (～3.8 km/s) for the olivine gabbro studied are comparable to those of seismic layer 3 in the WP‐2 area, the estimated vertical gradients of intrinsic velocities are significantly smaller than those reported from layer 3. These results suggest that velocity profiles of layer 3 in the WP‐2 area may reflect the presence of a minor porosity in lower oceanic crust, which closes with increasing depth and/or continuous changes in mineralogy of layer 3 rocks.  相似文献   

Sensitive determination of enzymatically labile dissolved organic phosphorus and its vertical profiles in the oligotrophic western North Pacific and East China Sea     

Fuminori Hashihama  Shinko Kinouchi  Shuhei Suwa  Masahiro Suzumura  Jota Kanda 《Journal of Oceanography》2013,69(3):357-367

Trace concentrations of labile dissolved organic phosphorus (LDOP) in oligotrophic seawater were measured by use of an enzymatic procedure and a nanomolar phosphate analytical system consisting of a gas-segmented continuous flow analyzer with a liquid waveguide capillary cell. LDOP, defined as DOP hydrolyzed by alkaline phosphatase (AP) from Escherichia coli, was quantified as the difference between the phosphate concentrations of the seawater sample with and without AP treatment. For sensitive measurement of LDOP, we found that phosphate contamination derived from commercially available AP must be corrected, and azide treatment before AP treatment proved effective in removing biological effect that occurs during DOP hydrolysis. Field observations at six stations of the western North Pacific and the East China Sea during the boreal summer revealed that, in the upper 200 m of the water column, LDOP concentrations ranged from the detection limit (3 nM) to 243 nM, and phosphate concentrations ranged from 5 to 374 nM. The spatial distribution patterns of LDOP were similar to those of phosphate. Most of the depth profiles for LDOP and phosphate showed concentrations were extremely low, <25 nM, between the surface and the deep chlorophyll maximum layer (DCML) and increased below the DCML. Strongly depleted LDOP and phosphate above the DCML suggest that LDOP is actively hydrolyzed under phosphate-depleted conditions and utilized by microbes.  相似文献   

A modified method for estimating vertical profiles of turbulent dissipation rate using density inversions in the Kuril Straits     

Masahiro Yagi  Ichiro Yasuda 《Journal of Oceanography》2013,69(2):203-214

To address the lack of directly measured turbulence data in the Kuril Straits, an existing method was modified to indirectly estimate continuous vertical profiles of turbulent energy dissipation rate ε by using density inversions. A linear relationship was confirmed between directly measured ε and indirectly estimated ε from the existing method, where most of the detected density inversions were discarded as noise. The existing method thus yielded large gaps in the vertical profiles, and the gaps were much greater than the observed mean autocorrelation vertical length scale of about 10 m. To reduce these gaps and produce reasonable estimates for vertical ε profiles, the quality tests were carefully re-examined with directly measured ε data, and one of the quality tests (the water mass test) was excluded because the test rejects real density inversions even with large ε. With this modification, and interpolation and smoothing of the indirectly estimated ε with the mean correlation length scale, continuous vertical ε profiles were obtained. These profiles have an error factor of 3.3 corresponding to one standard deviation of the ratio between directly observed and estimated data, and 95 % of the data were within a factor of 10.5, with the overall correlation coefficient between smoothed directly measured ε and estimated ε equal to 0.80. This method could be useful for areas where 10^?9 < ε < 10^?6.5 W/kg, and where vertical distances between adjacent density inversions are mostly less than the mean autocorrelation scale.  相似文献   

Fast and slow timescales in the tropical low-cloud response to increasing CO2 in two climate models     

Masahiro Watanabe  Hideo Shiogama  Masakazu Yoshimori  Tomoo Ogura  Tokuta Yokohata  Hajime Okamoto  Seita Emori  Masahide Kimoto 《Climate Dynamics》2012,39(7-8):1627-1641

To obtain physical insights into the response and feedback of low clouds (C _l ) to global warming, ensemble 4?×?CO₂ experiments were carried out with two climate models, the Model for Interdisciplinary Research on Climate (MIROC) versions 3.2 and 5. For quadrupling CO₂, tropical-mean C _l decreases, and hence, acts as positive feedback in MIROC3, whereas it increases and serves as negative feedback in MIROC5. Three time scales of tropical-mean C _l change were identified—an initial adjustment without change in the global-mean surface air temperature, a slow response emerging after 10–20?years, and a fast response in between. The two models share common features for the former two changes in which C _l decreases. The slow response reflects the variability of C _l associated with the El Ni?o-Southern Oscillation in the control integration, and may therefore be constrained by observations. However, the fast response is opposite in the two models and dominates the total response of C _l . Its sign is determined by a subtle residual of the C _l increase and decrease over the ascending and subsidence regions, respectively. The regional C _l increase is consistent with a more frequent occurrence of a stable condition, and vice versa, as measured by lower-tropospheric stability (LTS). The above frequency change in LTS is similarly found in six other climate models despite a large difference in both the mean and the changes in the low-cloud fraction for a given LTS. This suggests that the response of the thermodynamic constraint for C _l to increasing CO₂ concentrations is a robust part of the climate change.  相似文献   

An empirical probabilistic approach for constraining the uncertainty of long-term solute transport predictions in fractured rock using in situ tracer experiments     

Masahiro Uchida  William Dershowitz  Glori Lee  Dawn Shuttle 《Hydrogeology Journal》2009,17(5):1093-1110

Although radionuclide tracer tests have been carried out for over 30  years, the role of tracer tests in radioactive waste repository performance assessment (PA) has been questioned due to the differences between the time scales for tracer tests and PA. The possibility of using in situ tracer tests to constrain PA time scale (over 10,000  years) solute transport has been demonstrated using a systematic “microstructural model” approach to define advective and retentive materials. A series of simulations were conducted of the “TRUE-1” sorbing solute transport experiments in a well-characterized block of fractured granite. These experiments were then used to constrain the uncertainty of long-term transport on the same pathways, using a gradient several orders of magnitude smaller. The comparison of uncertainty of this long-term transport, with and without this conditioning step, provided a measure of the ability of tracer tests to reduce PA time-scale uncertainty. Although this approach for quantifying uncertainty reduction is somewhat empirical, it does indicate the potential usefulness of tracer experiments in reducing the uncertainty of the key PA time-scale transport parameters such as the flow wetted surface, provided that immobile zone properties such as sorption (Kd), porosity and diffusivity are available.  相似文献   

Coupling fluvial processes and landslide distribution toward geomorphological hazard assessment: a case study in a transient landscape in Japan   总被引：1，自引：0，他引：1  

Ching-Ying Tsou  Masahiro Chigira  Yuki Matsushi  Narumi Hiraishi  Noriyuki Arai 《Landslides》2017,14(6):1901-1914

This study quantified the relationship among deep-seated gravitational slope deformations (DGSDs), landslides, and river rejuvenation in the upper reaches of the Kumano River in the Kii Mountains of Japan, an area of frequent bedrock landslides. River profiles and hillslope landforms were examined, and high-resolution digital elevation models (DEMs) were used to identify DGSDs and landslides. Many of the deep-seated landslides were associated with rainstorms in 1889 and 2011. Landslide volumes were related to landslide areas on the basis of 52 deep-seated landslides that failed during the 2011 rainfall, providing basic data for landscape denudation and sediment yield. River rejuvenation occurred stepwise, incising moderate relief paleosurfaces and forming two series of knickpoints and V-shaped inner gorges that are up to 400-m deep. More than 65% of DGSDs and 75% of the landslides were located in association with the incised inner gorges along the peripheries of the paleosurfaces or were entirely contained within the inner gorges. DGSDs and landslides associated with the incised inner valley slopes tended to be larger than those developed within the paleosurfaces and may be long-term transient hillslope responses to river incision. Hillslope undercutting caused by rejuvenated river incision may play an important role in long-term slope stability and distribution of mass movements, and could serve as an indicator of landslide hazard.  相似文献   

Determination of Abundances of Fifty‐Two Elements in Natural Waters by ICP‐MS with Freeze‐Drying Pre‐concentration     

Que D. Hoang  Tak Kunihiro  Chie Sakaguchi  Masahiro Yamanaka  Hiroshi Kitagawa  Eizo Nakamura 《Geostandards and Geoanalytical Research》2019,43(1):147-161

To precisely determine the abundances of fifty‐two elements found within natural water samples, with mass fractions down to fg g^?1 level, we have developed a method which combines freeze‐drying pre‐concentration (FDC) and isotope dilution internal standardisation (ID‐IS). By sublimation of H₂O, the sample solution was reduced to < 1/50 of the original volume. To determine element abundance with accuracy better than 10%, we found that for solutions being analysed by mass spectrometry the HNO₃ concentration should be > 0.3 mol l^?1 to avoid hydrolysis. Matrix‐affected signal suppression was not significant for the solutions with NaCl concentrations lower than 0.2 and 0.1 cg g^?1 for quadrupole ICP‐MS and sector field ICP‐MS, respectively. The recovery yields of elements after FDC were 97–105%. The detection limits for the sample solutions prepared by FDC were ≤ 10 pg g^?1, except for Na, K and Ca. Blanks prepared using FDC were at pg‐levels, except for eleven elements (Na, Mg, Al, P, Ca, Mn, Fe, Co, Ni, Cu and Zn). The abundances of fifty‐two elements in bottled drinking water were determined from five different geological sources with mass fractions ranging from the fg g^?1 to μg g^?1 level with high accuracy.  相似文献   

Partitioning of heavy metals into mineral and organic fractions in a sediment core from Tokyo Bay     

Yasushi Kitano  Masahiro Sakata  Eiji Matsumoto 《Geochimica et cosmochimica acta》1980,44(9):1279-1285

Sediment core was collected from Tokyo Bay. The surface enrichment of heavy metals due to human activities is recognized in the sediment. Partitioning of Cu, Zn, Fe and Mn into sulfide, carbonate, organic and silicate fractions has been determined with selective chemical leaching techniques for ²¹⁰Pb-dated sediment core samples. The heavy metal contents of silicate fractions without exchangeable sites are almost constant against depth in sediment core. However, the Cu, Zn and Mn contents of sulfide, carbonate and organic fractions vary with depth. Most Cu and Zn in the polluted sediment layer are associated with the iron sulfide fraction.  相似文献   

Thermal diffusivity of stishovite     

Masahiro Osako  Yoji Kobayashi 《Physics of the Earth and Planetary Interiors》1979,18(2):P1-P4

The thermal diffusivity of synthetic polycrystalline stishovite was determined by the Ångstrom method in the temperature range 300–550 K at 1 atm. The calculated thermal conductivity of stishovite at 300 K is 0.086 W cm^?1 K^?1 which is comparable to that for TiO₂-rutile but much lower than for GeO₂ and SnO₂. The observed thermal conductivities of rutile-structure oxides increase systematically with increasing density, in contrast with the expected behavior for isostructural compounds.  相似文献