Coupling behavior of shear deformation and end rotation of elastomeric seismic isolation bearings          下载免费PDF全文

Ken Ishii  Masaru Kikuchi  Takuya Nishimura  Cameron J. Black 《地震工程与结构动力学》2017,46(4):677-694

This paper presents a mechanical model for predicting the behavior of elastomeric seismic isolation bearings subject to combined end rotations and shear deformation. The mechanical model consists of a series of axial springs at the top, mid‐height and bottom of the bearing to vertically reproduce asymmetric bending moment distribution in the bearings. The model can take into account end rotations of the bearing, and the overall rotational stiffness includes the effect of the variation of vertical load on the bearing and the imposed shear deformation. Static bending tests under various combinations of vertical load and shear deformation were performed to identify the mechanical characteristics of bearings. The test results indicate that bearing rotational stiffness increases with increasing vertical load but decreases with increasing shear deformation. Simulation analyses were conducted to validate the new mechanical model. The results of analyses using the new model show very good agreement with experimental observations. A series of seismic response analyses were performed to demonstrate the dynamic behavior of top‐of‐column isolated structures, a configuration where the end rotations of isolation bearings are typically expected to be larger. The results suggest that the end rotations of elastomeric bearings used in practical top‐of‐column isolated structures do not reduce the stability limit of isolation system. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Self-affinities of landforms and folds in the Northeast Honshu Arc, Japan     

Kazuhei Kikuchi  Kazutoshi Abiko  Hiroyuki Nagahama  Hiroshi Kitazato  Jun Muto 《Acta Geophysica》2013,61(6):1642-1658

A method to analyze self-affinities is introduced and applied to the large scale fold geometries of Quaternary and Tertiary sediments or geographical topographies in the inner belt of the Northeast Honshu Arc, Japan. Based on this analysis, their geometries are self-affine and can be differently scaled in different directions. We recognize a crossover from local to global altitude (vertical) variation of the geometries of folds and topographies. The characteristic length for the crossover of topographies (landforms) is about 25 km and is related to the half wavelength of the crustal buckling folds or possible maximum magnitude of inland earthquakes in the Northeast Honshu Arc. Moreover, self-affinity of the folds and topographies can be connected with the b-value in Gutenberg-Richter℉s law. We obtain two average Hurst exponents obtained from the self-affinities of folds in the Northeast Honshu Arc. This indicates that there are two possible seismic modes for the smaller and larger ranges in the focal regions in the Northeast Honshu Arc.  相似文献   

Intensity variations of the postnoon auroral bright spots observed at Zhongshan Station, Antarctica on August 8, 1999     

艾勇  邓晓华  刘瑞源  杨惠根 《极地研究(英文版)》2002,13(1)

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅａｆｔｅｒｎｏｏｎｒｅｇｉｏｎ (ａｐｐｒｏｘｉｍａｔｅｌｙ 1 4 0 0ｔｏ 1 60 0ＭＬＴ)ｈａｓａｓｐｅｃｉａｌｓｉｇｎｉｆｉｃａｎｃｅｆｏｒａｖａｒｉｅｔｙｏｆｍａｇｎｅｔｏｓｐｈｅｒｉｃｐｈｅｎｏｍｅｎａ.Ｉｔｓｐｒｏｘｉｍｉｔｙｔｏｍａｇｎｅｔｉｃｎｏｏｎｓｕｇｇｅｓｔｓｔｈａｔｔｈｅａｕｒｏｒａｌｐｈｅｎｏｍｅｎａｏｂｓｅｒｖｅｄｍａｙｂｅｒｅｌａｔｅｄｔｏｄａｙｓｉｄｅｍａｇｎｅｔｏｓｐｈｅｒｉｃｐｒｏｃｅｓｓｅｓ ,ａｎｄｉｎｄｅｅｄａｖａｒｉｅｔｙｏｆｓｔｕ…  相似文献   

Bimodal representation of the tropical intraseasonal oscillation   总被引：2，自引：1，他引：1  

Kazuyoshi Kikuchi  Bin Wang  Yoshiyuki Kajikawa 《Climate Dynamics》2012,38(9-10):1989-2000

The tropical intraseasonal oscillation (ISO) shows distinct variability centers and propagation patterns between boreal winter and summer. To accurately represent the state of the ISO at any particular time of a year, a bimodal ISO index was developed. It consists of Madden-Julian Oscillation (MJO) mode with predominant eastward propagation along the equator and Boreal Summer ISO (BSISO) mode with prominent northward propagation and large variability in off-equatorial monsoon trough regions. The spatial–temporal patterns of the MJO and BSISO modes are identified with the extended empirical orthogonal function analysis of 31?years (1979–2009) OLR data for the December–February and June–August period, respectively. The dominant mode of the ISO at any given time can be judged by the proportions of the OLR anomalies projected onto the two modes. The bimodal ISO index provides objective and quantitative measures on the annual and interannual variations of the predominant ISO modes. It is shown that from December to April the MJO mode dominates while from June to October the BSISO mode dominates. May and November are transitional months when the predominant mode changes from one to the other. It is also shown that the fractional variance reconstructed based on the bimodal index is significantly higher than the counterpart reconstructed based on the Wheeler and Hendon’s index. The bimodal ISO index provides a reliable real time monitoring skill, too. The method and results provide critical information in assessing models’ performance to reproduce the ISO and developing further research on predictability of the ISO and are also useful for a variety of scientific and practical purposes.  相似文献   

南极中山站午后极光强度与太阳风参数的关系          下载免费PDF全文

胡红桥  刘瑞源  杨惠根  王敬芳  Natsuo Sato  Masayu kiKikuchi  李升贵 《极地研究》2001,13(3):151-158

本文利用1997年和1998年南极中山站多通道扫描光度计的地面观测数据和WIND卫星在弓激波上游对太阳风参数的观测数据，对午后高纬极光强度与太阳风等离子体密度、动压以及太阳风速度之间的相关性进行了定量研究。研究表明，午后极光630．0nm的强度与太阳风等离子体参数之间有较好的相关，630．0nm的强度表现出随太阳风等离子体密度、动压和速度的增大而增加的趋势，其相关系数分别为0．84、0．88和0．61；而557．7nm极光的强度与太阳风等离子体参数之间的相关较差。午后557．7nm极光的强度与太阳风等离子体参数之间的相关较差。午后557．7nm和630．0nm对太阳风参数的不同响应表明太阳风对630．0nm影响更直接，而557．7nm受到了磁层动力学过程的影响。  相似文献   

Organizations and the interior characteristics of winter monsoon clouds by dual-polarization Doppler radar observation in Hokuriku, Japan     

Yoshio Asuma  Katsuhiro Kikuchi  Hiroshi Uyeda 《Atmospheric Research》1997,43(4):297-314

To understand the characteristics of winter monsoon clouds, dual-polarization Doppler radar observations were carried out at Mihama, Hokuriku, Japan. A series of organized disturbances associated with the passage of a cyclonic circulation was analyzed. The following scenario was proposed. Environmental circumstances, for example, temperature and wind profiles, surface heat and moisture fluxes, etc., determine the organizational style of mesoscale convections. This organization regulates the convection interior flow pattern including the location and intensity of updrafts. Subsequently, it influences interior microphysical properties, for example, the types of precipitation particles, their growth and distributions, their electrification, etc. In this paper, an observational example following this scenario is presented.  相似文献   

A decade of the Super Dual Auroral Radar Network (SuperDARN): scientific achievements, new techniques and future directions   总被引：2，自引：0，他引：2  

G. Chisham  M. Lester  S. E. Milan  M. P. Freeman  W. A. Bristow  A. Grocott  K. A. McWilliams  J. M. Ruohoniemi  T. K. Yeoman  P. L. Dyson  R. A. Greenwald  T. Kikuchi  M. Pinnock  J. P. S. Rash  N. Sato  G. J. Sofko  J.-P. Villain  A. D. M. Walker 《Surveys in Geophysics》2007,28(1):33-109

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High Ash Content in Net-Plankton Samples from Shallow Coastal Water: Possible Source of Error in Dry Weight Measurement of Zooplankton Biomass   总被引：2，自引：0，他引：2  

Norio Nagao  Tatsuki Toda  Kazutaka Takahashi  Koji Hamasaki  Tomohiko Kikuchi  Satoru Taguchi 《Journal of Oceanography》2001,57(1):105-107

Annual examination of net-plankton biomass in dry weight, ash-free dry weight, organic carbon, and nitrogen weight at the Manazuru harbor, central Japan revealed that net-plankton samples from shallow coastal water contained considerable amount of ash (53±13% of dry weight) which would be caused by contamination of inorganic materials from re-suspendion of sediments, terrestrial runoff and chain-forming diatoms. Therefore, in coastal water, dry weight is inadequate fro determination of zooplankton biomass in volving the possibility of over-estimation. Practical estimation of net-plankton biomass in shallow coastal waters, ash-free dry weight, organic carbon, and/or nitrogen are more adequate.  相似文献   

Mineralogical and Geochemical Characteristics of the Utanobori Gold Deposit in Northern Hokkaido,Japan     

Thomas T. Sorulen  Ryohei Takahashi  So Tanaka  Kana Suzuki  Akira Imai  Yasushi Watanabe  Shingo Kikuchi 《Resource Geology》2019,69(4):402-429

The Utanobori gold deposit is a low‐sulfidation, epithermal vein‐type deposit located in northern Hokkaido, Japan. The deposit is hosted by conglomerate, sandstone, and tuff of the Middle to Late Miocene Esashi Formation. These rocks were hydrothermally altered. Silica sinters and quartz‐adularia veins are common in the deposit. The quartz‐adularia veins either contain a ginguro band, which corresponds to the main gold‐bearing vein (Type 1 Veins), or do not contain a ginguro band but contain minor adularia (Type 2 Veins). Type 1 Veins are divided into three stages with 12–14 substages. Ore minerals identified include electrum, naumannite, chlorargyrite, bromargyrite, an unidentified Fe‐Sb mineral, and an Fe‐(Sb)‐As mineral. These ore minerals formed in the main mineralization stages I (bands I‐b and I‐d) and II (band II‐a). Scanning electron microscopy with cathodoluminescence images show that cathodoluminescence‐dark microcrystalline quartz exhibiting colloform (ghost‐sphere) texture is closely associated with ore minerals in the Type 1 Vein and Type 2 Vein, and the Al and K contents of such quartz are commonly >1000 ppm. This indicates that the ore minerals were crystallized from alkaline, silica‐saturated fluids at temperatures <200°C, which initially deposited amorphous silica that was recrystallized to microcrystalline quartz. The average Au content of electrum is 52.5 at% Au (n = 10), 65.7 at% Au (n = 20), and 55.5 at% Au (n = 5) in bands I‐b, I‐d, and II‐a, respectively, of Type 1 Veins. The δ³⁴S_CDT values of two fine‐grained disseminated pyrites in the altered conglomerate and bedded tuff in the argillic altered zone are ?4.3 and ?4.2‰. Ar‐Ar dating on adularia yielded 13.6 ± 0.06 Ma, 13.6 ± 0.07 Ma, and 13.6 ± 0.06 Ma for the stages I, II, and III of the Type 1 Vein, respectively. K‐Ar ages determined on adularia in the silica sinter and on whole‐rock of glassy rhyolite of the Esashi Formation are 15.0 ± 0.4 Ma and 14.6 ± 0.4 Ma, respectively. These radiometric ages indicate that silica sinter associated with the rhyolitic volcanic rocks formed prior to the main gold mineralization.  相似文献   

Estimation of the apertures of water-saturated fractures by nuclear magnetic resonance well logging   总被引：1，自引：0，他引：1  

Yoshito Nakashima  Tsuneo Kikuchi 《Geophysical Prospecting》2007,55(2):235-254

Fracture aperture is an important transport property in subsurface hydrology because it influences well productivity and the volume of the water resource. Nuclear magnetic resonance (NMR) well logging measures the hydrogen‐bearing fluid molecules in porous or fractured strata, and the NMR signal intensity increases with the amount of fluid in the sensed region of the NMR sonde. Fluid confined in a large fracture of >>0.2 mm in aperture has T2 (i.e. spin‐spin relaxation time) values as long as those of the bulk fluid. The bulk‐fluid porosity (i.e. porosity calculated using this long T2 component in a T2 histogram data) increases linearly with aperture. Therefore, NMR logging enables quantitative estimation of fracture apertures of >>0.2 mm using the bulk‐fluid porosity data if the calibration of the NMR sonde is performed adequately. We applied NMR logging to a borehole in a Holocene andesite lava at Sumikawa, Japan, to estimate the aperture of open fractures within the lava. A test well of 100 m depth and 20 cm diameter, filled with bentonite drilling mud, was scanned with an NMR sonde to obtain a profile of the porosity and the T2 histogram of the andesite. The bulk‐fluid porosity was calculated from the T2 histogram data, as the porosity at which the T2 value is larger than or equal to a threshold T2 of bulk bentonite mud. The bulk‐fluid porosity of a specific inclined fracture responsible for the total loss of circulation at 61.2 m depth during drilling was calculated assuming a threshold or T2 cut‐off of 33 ms, and again for a cut‐off of 100 ms. Calibration of the NMR sensor in a laboratory and measurement of the fracture dip angle by electrical microimaging logging enabled us to estimate the fracture aperture as 1.7 cm, assuming a T2 cut‐off of 33 ms, or 1.6 cm for a T2 cut‐off of 100 ms. The method of aperture determination described in this study is independent of fluid species and lithology, and is applicable to various hydrogen‐bearing borehole fluids (clean water, mud and oil) and geological settings.  相似文献