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21.
This paper shows an explanatory tool (a FORTRAN program linked to GIS software), called VCM (Variable Clumping Method), for
detecting statistically significant `multi-level clumps' in the distribution of points. The multi-level clumps imply a set
of clumps whose clumping radius varies from a small radius to a large radius (in spirits, VCM is similar to the K-function method). Compared with the ordinary (fixed radius) clumping method, VCM can detect overall significant clumps in
the distribution of points.
Received: 8 March 1999/Accepted: 17 September 1999 相似文献
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Ario Ceccotti Carmen Sandhaas Minoru Okabe Motoi Yasumura Chikahiro Minowa Naohito Kawai 《地震工程与结构动力学》2013,42(13):2003-2021
Multi‐storey buildings made of cross‐laminated timber panels (X‐lam) are becoming a stronger and economically valid alternative in Europe compared with traditional masonry or concrete buildings. During the design process of these multi‐storey buildings, also their earthquake behaviour has to be addressed, especially in seismic‐prone areas such as Italy. However, limited knowledge on the seismic performance is available for this innovative massive timber product. On the basis of extensive testing series comprising monotonic and reversed cyclic tests on X‐lam panels, a pseudodynamic test on a one‐storey X‐lam specimen and 1D shaking table tests on a full‐scale three‐storey specimen, a full‐scale seven‐storey building was designed according to the European seismic standard Eurocode 8 and subjected to earthquake loading on a 3D shaking table. The building was designed with a preliminary action reduction factor of three that had been derived from the experimental results on the three‐storey building. The outcomes of this comprehensive research project called ‘SOFIE – Sistema Costruttivo Fiemme’ proved the suitability of multi‐storey X‐lam structures for earthquake‐prone regions. The buildings demonstrated self‐centring capabilities and high stiffness combined with sufficient ductility to avoid brittle failures. The tests provided useful information for the seismic design with force‐based methods as defined in Eurocode 8, that is, a preliminary experimentally based action reduction factor of three was confirmed. Valid, ductile joint assemblies were developed, and their importance for the energy dissipation in buildings with rigid X‐lam panels became evident. The seven‐storey building showed relatively high accelerations in the upper storeys, which could lead to secondary damage and which have to be addressed in future research. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
23.
X-ray CT based numerical analysis of fracture flow for core samples under various confining pressures 总被引：1，自引：0，他引：1
Noriaki Watanabe Takuya Ishibashi Yutaka Ohsaki Yoshihiro Tsuchiya Tetsuya Tamagawa Nobuo Hirano Hiroshi Okabe Noriyoshi Tsuchiya 《Engineering Geology》2011,(4):338
The X-ray CT based numerical analysis of fracture flow for core samples, recently developed by the authors, was applied to two granite core samples having either a mated artificial or a mated natural fracture at confining pressures of 5 to 50 MPa. A third-generation medical X-ray CT scanner was used to image the samples within a core holder consisting of an aluminum liner and a carbon fiber overwrap. Fracture models (i.e., aperture distributions) were obtained by the CT images, the resolution of which was coarser than the apertures, and a single-phase flow simulation was performed using a local cubic law-based fracture flow model. Numerical results were evaluated by a fracture porosity measurement and a solution displacement experiment using NaCl and NaI aqueous solutions. These numerical results coincided only qualitatively with the experimental results, primarily due to image noise from the aluminum liner of the core holder. Nevertheless, the numerical results revealed flow paths within the fractures and their changes with confining pressure, whereas the experimental results did not provide such results. Different stress-dependencies in the flow paths were observed between the two samples despite the similar stress-dependency in fracture porosity and permeability. The changes in total area of the flow paths with confining pressure coincided qualitatively with changes in breakthrough points in the solution displacement experiment. Although the data is limited, the results of the present study suggest the importance of analyzing fluid flows within naturally fractured core samples under in situ conditions in order to better understand the fracture flow characteristics in a specific field. As demonstrated herein, X-ray CT-based numerical analysis is effective for addressing this concern. Using a multi-phase flow model, as well as a core holder constructed of an engineered plastic, should provide a useful, non-destructive, and non-contaminative X-ray CT-based fracture flow analysis for core samples under in situ conditions in future studies. 相似文献
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The SANET Toolbox: New Methods for Network Spatial Analysis 总被引：3，自引：0，他引：3
This paper describes new methods, called network spatial methods, for analyzing spatial phenomena that occur on a network or alongside a network (referred to as network spatial phenomena). First, the paper reviews network spatial phenomena discussed in the related literature. Second, the paper shows the uniform network transformation, which is used in the study of non‐uniform distributions on a network, such as the densities of traffic and population. Third, the paper outlines a class of network spatial methods, including nearest neighbor distance methods, K‐function methods, cell count methods, clumping methods, the Voronoi diagrams and spatial interpolation methods. Fourth, the paper shows three commonly used computational methods to facilitate network spatial analysis. Fifth, the paper describes the functions of a GIS‐based software package, called SANET, that perform network spatial methods. Sixth, the paper compares network spatial methods with the corresponding planar spatial methods by applying both methods to the same data set. This comparison clearly demonstrates how different conclusions can result. The conclusion summarizes the major findings. 相似文献
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Yoshimasa Toyota Shiro Okabe Satoru Kanamori Yasushi Kitano 《Journal of Oceanography》1983,38(6):357-361
A simple and rapid coprecipitation method for the determination of several trace metals in seawater is presented. These metals are coprecipitated with lanthanum hydroxide, the precipitate is dissolved, and then the metals are determined by atomic absorption spectrometry. Lanthanum hydroxide was chosen as a coprecipitant for the following reasons, (a) lanthanum hydroxide has a sufficiently low solubility and forms an easily filterable flocculate at about 80C, and (b) lanthanum has an absorption wavelength that is sufficiently separated from those of the other elements to be analysed, i.e., Mn, Fe, Ni, Cu and Zn. Experimental results show that these metals are coprecipitated by the present method with excellent recoveries. 相似文献
29.
The behavior of transition metals (Co, Ni, Cu and Zn) on precipitation of manganese oxides from seawater pumped up from a
well at the site of the Marine Science Museum, Tokai University, and collected from several tanks along the water supply system
to an aquarium was investigated. The distribution coefficients of cobalt and nickel between manganese oxides and seawater
were different at different sampling points along the water supply system. At sampling points with high rates of manganese
oxide precipitation, the distribution coefficients were about one order of magnitude smaller than those at the points with
low precipitation rates, while there were no remarkable differences in the distribution coefficients of copper and zinc among
the sampling points. The distribution coefficients of minor transition metals, with the exception of copper, observed at the
points with low precipitation rates were comparable to those measured experimentally using manganese dioxides. 相似文献
30.
Speciation Study of Cr in a Geochemical Reference Material Sediment Series Using Sequential Extraction and XANES Spectroscopy 
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下载免费PDF全文 Atsuyuki Ohta 《Geostandards and Geoanalytical Research》2015,39(1):87-103
Speciation of Cr in geochemical reference materials was characterised by sequential extraction and X‐ray absorption near‐edge structure (XANES) spectroscopy to identify Cr(III) resulting from the reduction of pollutant Cr(VI). Sequential extraction suggested that the amount of Cr associated with an acetic acid soluble fraction was low; Cr associated with a reducible phase and an oxidisable phase was extracted at 5–10% of the total Cr concentration, and the residual phase was found to be the dominant Cr‐containing fraction. Cr speciation in soil artificially doped with Cr(VI) and sediment samples collected from highly populated and industrialised areas was different from that in naturally occurring materials. Substantial Cr was extracted as a reducible phase (15–30%) and an oxidisable phase (30–60%) for these samples. Through subsequent XANES spectroscopy analysis, the reducible phase was explained by Cr bound to Fe hydroxide, while the oxidisable phase was a mixture of Cr bound to humic substances and Cr hydroxides. That is, Cr(VI) present as a contaminant in sediments and soils was reduced to Cr(III), which then bound to Fe hydroxide and humic substances, precipitating as a hydroxide. Thus, a combination of sequential extraction and XANES spectroscopy allows for effective identification and quantification of the chemical forms of Cr in sediments and soils. 相似文献