Analysis of tubular steel bridge piers     

Toshiki Ishizawa  Masashi Iura 《地震工程与结构动力学》2005,34(8):985-1004

A one‐dimensional model is proposed for the static and dynamic analysis of tubular steel bridge piers subjected to strong ground motions. The present formulation does not require experimental results nor shell analysis to obtain the constitutive equation of the model, which shows strength deterioration. The material properties and dimensions of bridge piers are required for static and dynamic analysis of the present model. The present analysis consists of two steps. The first step is to obtain the stress and strain relationship of the base plastic‐hinge region, where local inelastic buckling is observed. The modified Shanley's model and fiber elements are used to establish the compressive skeleton curve. The strength deterioration is taken into account in the resulting constitutive model. The second step is to analyze static and dynamic responses of tubular steel bridge piers. For overall analysis, the base plastic‐hinge region is discretized in the circumferential direction by using fiber elements whose constitutive equation was obtained in the first step. The validity of the present model has been confirmed through comparisons with existing experimental results. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Incorporation of Be isotopes and other trace metals into marine ferromanganese deposits     

Masashi Kusakabe  Teh-Lung Ku 《Geochimica et cosmochimica acta》1984,48(11):2187-2193

Two-to threefold inward increase of ¹⁰Be, ⁹Be, Cu and Ni have been found in surface layers of marine ferromanganese deposits. We interpret this phenomenon as reflecting the manner in which the Be isotopes and probably other trace metals (e.g. Cu and Ni) are incorporated. On reaching the sea floor exchangeable Be is released from its carrier phase to the pore water of the ferromanganese deposits, diffuses inward and gets fixed into the deposits. The fixation process may be related to the mineralogical reorganizations suggested by previous studies. We have modeled this concept and applied it to a Mn crust on which detailed analyses of Cu, Ni and natural decay-series nuclides, as well as Be isotopes are made. Post-depositional fixation of Th isotopes may also occur. The redistributions of Be and Th isotopes are confined to regions very close to the surface of the deposits. For all practical purposes, they will not affect growth rate determinations conventionally done using these isotopes. The “linearly” extrapolated ${}^{10}\text{Be}{}^9\text{Be}$ ratio to the surface from deep layers of a Mn deposit does not necessarily represent that ratio in sea water.  相似文献   

A nonlinear parametric model based on a power law relationship for predicting the coastal tsunami height     

Yoshikawa  Masashi  Igarashi  Yasuhiko  Murata  Shin  Baba  Toshitaka  Hori  Takane  Okada  Masato 《Marine Geophysical Researches》2019,40(4):467-477

When a subduction-zone earthquake occurs, the tsunami height must be predicted to cope with the damage generated by the tsunami. Therefore, tsunami height prediction methods have been studied using simulation data acquired by large-scale calculations. In this research, we consider the existence of a nonlinear power law relationship between the water pressure gauge data observed by the Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) and the coastal tsunami height. Using this relationship, we propose a nonlinear parametric model and conduct a prediction experiment to compare the accuracy of the proposed method with those of previous methods and implement particular improvements to the extrapolation accuracy.

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A possible substellar companion to the intermediate-mass giant HD 175679     

Liang Wang  Bun＇ei Sato  Gang Zhao  Yu-Juan Liu  Kunio Noguchi  Hirovasu Ando  Hideyuki Izumiura  Eiji Kambe  Masashi Omiya  Hiroki Harakawa  Fan Liu  Xiao-Shu Wu  Yoichi Takeda  Michitoshi Yoshida  Eiichiro Kokubo 《天体物理学报》2012,(1):84-92

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Performances of Landfill Liners under Dry and Wet Conditions     

Saravanan Mariappan  Masashi Kamon  Faisal Haji Ali  Takeshi Katsumi  Tomoyuki Akai  Toru Inui  Masaki Nishimura 《Geotechnical and Geological Engineering》2011,29(5):881-898

This paper addresses the study conducted on the performance of landfill liner interface parameters. Interface shear strength parameters for various combinations of 9 different lining materials were studied and presented in this paper. This comprehensive testing program covers the interfaces between: (1) soil and compacted clay liner (CCL), (2) geomembrane (HDPEs or PVC) and soil, (3) geosynthetic clay liner (GCL)/CCL and soil, (4) geomembrane and geotextile, (5) geotextile and soil, (6) geotextile and GCL/CCL, and (7) geomembrane and GCL/CCL. The experiments were conducted for both at dry or optimum moisture condition and at saturated or wet condition. The interface performance under both conditions were compared to access the material performances. Tabulated summaries of interface test data under dry or optimum moisture condition (OMO) and saturated or wet condition are presented in the paper.  相似文献   

Formation and evolution of the Magellanic Clouds – I. Origin of structural, kinematic and chemical properties of the Large Magellanic Cloud     

Kenji Bekki  Masashi Chiba 《Monthly notices of the Royal Astronomical Society》2005,356(2):680-702

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Evidence of earth catastrophe by anomalous shocked quartz at the K/T boundary     

YASUNORI MIURA  Toshio KATO  Masashi Imai 《Celestial Mechanics and Dynamical Astronomy》1992,54(1-3):249-253

Anomalous shocked quartz with high density (less than 1 % of density-deviation) is considered to be a relict of ultra high-pressure at meteoritic impact. The shocked quartz grains can be found only in terrestrial and artificial impact craters, meteorites and the Cretaceous-Tertiary (K/T) boundary samples. Volcanic activity is considered to be started or accelerated by enormous impact event.  相似文献   

Spatiotemporal characteristics of the displacement field revealed with principal component analysis and the mode-rotation technique     

Masashi Kawamura  Koshun Yamaoka   《Tectonophysics》2006,419(1-4):55-73

Principal component analysis (PCA) was applied to the displacement field recorded at 147 GPS stations in the Kanto-Tokai district, Japan, for the period from January 1999 to February 2003. Some prominent geophysical events occurred during this period. Using PCA, we attempted to decompose the displacement field into some representative spatial modes and their corresponding temporal modes to quantitatively extract the primary geophysical events that have caused rapid crustal deformation in this region. The displacement field was roughly decomposed into modes corresponding to the following three major events: (1) The Miyake-Kozu volcanic event, which occurred in the region south of Tokyo in 2000. It included large-scale dyke intrusion and intensive earthquake swarm between the Miyakejima and Kozushima islands. (2) The Tokai slow-slip event, which is considered to have begun just after the Miyake-Kozu volcanic event and is ongoing as of November 2005. It occurred on the boundary between the subducting Philippine Sea Plate and the overriding Eurasian (Amurian) Plate in the Tokai district. (3) The Boso slow-slip event, which lasted for approximately 10 days in October 2002. It occurred on the boundary between the subducting Pacific Plate and the overriding North American Plate near the Boso Peninsula. In the decomposition process, we combined the mode-rotation technique with ordinary PCA. This is because PCA causes contamination between modes, i.e., a mode obtained with PCA is contaminated by other modes. For example, the first principal mode corresponding to the Miyake-Kozu volcanic event, which is by far the largest in magnitude, was clearly seen in many other modes. In order to remove such contamination, we applied the mode-rotation technique, in which the principal axes derived from PCA are rotated so as to minimize the correlation coefficients between different temporal modes for a time period in which some prominent change occurs. Combining the mode-rotation technique with PCA exhibited a better performance in separating the displacement field.  相似文献   

Ultrasonically enhanced electrokinetic remediation for removal of Pb and phenanthrene in contaminated soils   总被引：5，自引：0，他引：5  

Ha Ik Chung  Masashi Kamon   《Engineering Geology》2005,77(3-4):233-242

Electrokinetic and ultrasonic remediation technologies were studied for the removal of heavy metal and polycyclic aromatic hydrocarbon (PAH) in contaminated soils. The study emphasized the coupled effects of electrokinetic and ultrasonic techniques on migration as well as clean-up of contaminants in soils. The laboratory soil flushing tests combined electrokinetic and ultrasonic technique were conducted using specially designed and fabricated devices to determine the effect of both techniques. The electrokinetic technique was applied to remove mainly the heavy metal and the ultrasonic technique was applied to remove mainly organic substance in contaminated soil. A series of laboratory experiments involving electrokinetic and electrokinetic and ultrasonic flushing tests were carried out. Natural clay was used as a test specimen and Pb and phenanthrene were used as contaminants. An increase in out flow, permeability and contaminant removal rate was observed in electrokinetic and ultrasonic tests. Some practical implications of these results are discussed in terms of technical feasibility of in situ implementation of electrokinetic ultrasonic remediation technique.  相似文献   

Damage assessment after 2001 Gujarat earthquake using Landsat-7 satellite images     

Yalkun Yusuf  Masashi Matsuoka  Fumio Yamazaki 《Journal of the Indian Society of Remote Sensing》2001,29(1-2):17-22

In this paper, we present a method of earthquake damage detection by comparing the optical images with panchromatic bands for the Gujarat, India earthquake, which occurred on January 26, 2001. The data used in this study are optical remote sensing images taken by Landsat-7 satellite on January 8 and February 29, 2001, before and after the earthquake. We have investigated the pre and post-earthquake satellite images calculating the differences in the reflection intensity (digital number) of the two images. The estimated affected area has been subtracted on a pixel unit based on the obtained frequency distributions of the differences in the optical sensor values, which show significant changes in the reflectance due to the earthquake disaster. We have investigated the accuracy of our analysis result using a classification method for the training areas with aerial photographs taken after the earthquake. The two damage detection methods show a very similar result.  相似文献