Report of the International Symposium of IGCP-440 and LEGENDS Proposal in Sri Lanka, March-April 2003     

Masaru Yoshida  Yasuhito Osanai  Masaaki Owada  Nobuhiko Nakano  Wilbert K.W. Kehelpannala 《Gondwana Research》2003,6(4):939-941

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Proterozoic East Gondwana: Supercontinent Assembly and Breakup     

M. Yoshida  B.F. Windley  S. Dasgupta 《Gondwana Research》2003,6(4):960

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Evidence for fullerenes in solid bitumen from pillow lavas of Proterozoic age from Mítov (Bohemian Massif, Czech Republic)     

Jan Jehli?ka  Aleš Svatoš  Filip Uhlík 《Geochimica et cosmochimica acta》2003,67(8):1495-1506

Andesitic pillow lavas containing biogenic, solid bitumen (SB) are a constituent of a Neoproterozoic volcanosedimentary sequence (Teplá-Barrandian unit, Bohemian Massif) in the Mítov area of the Czech Republic. A black shale formation that is crosscut by these andesitic basalts is 565 Ma old. Carbon disulfide extracts of two powdered samples of SB contain 0.2 and 0.3 ppm of C₆₀, respectively, as determined by high-pressure liquid chromatography. The peak assignment based on retention time is fully supported by high-resolution electron ionization mass spectrometry (EI-MS). No C₇₀ was detected, nor was C₆₀ found in two other SB samples from this locality. Other investigated carbonaceous samples from Bohemia (coals and anthracites of Upper Paleozoic age and anthraxolite, graphitoids, and graphite of Upper Proterozoic age) did not contain fullerenes at concentrations above the detection limit of 0.01 ppm. The absence of C₆₀ in these samples was confirmed by EI-MS. The proposed mechanism of fullerene formation involves a primary algal phase, generation of a hydrocarbonaceous mixture in the course of thermal evolution of the sedimentary series, and their high-temperature transformation related to the extrusion of basalt. An important feature for fullerene conservation was the enclosure of fullerenes in SB with a structure similar to glasslike carbon, where the fullerene was protected against oxidation.  相似文献   

Aquatic chemistry: 3rd ed. by W. Stumm and J. J. Morgan. A Wiley-Interscience Publication, John Wiley & Sons, Inc., 1996, xvi + 1022p., US $29.95 (ISBN 0-471-51184-6)     

Tomas Pa?es 《Geochimica et cosmochimica acta》1996,60(24):5158-5159

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Quantitative methods in the earth sciences     

A. F?rster  D. F. Merriam 《Mathematical Geology》1997,29(2):315

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Simulation of normal distributed smooth fields by Karhunen-Loéve expansion in combination with kriging     

Nils-Otto Kitterr?d  Lars Gottschalk 《Stochastic Hydrology and Hydraulics》1997,11(6):459-482

Simulation of multigaussian stochastic fields can be made after a Karhunen-Loéve expansion of a given covariance function. This method is also called simulation by Empirical Orthogonal Functions. The simulations are made by drawing stochastic coefficients from a random generator. These numbers are multiplied with eigenfunctions and eigenvalues derived from the predefined covariance model. The number of eigenfunctions necessary to reproduce the stochastic process within a predefined variance error, turns out to be a cardinal question. Some ordinary analytical covariance functions are used to evaluate how quickly the series of eigenfunctions can be truncated. This analysis demonstrates extremely quick convergence to 99.5% of total variance for the 2nd order exponential (‘gaussian’) covariance function, while the opposite is true for the 1st order exponential covariance function. Due to these convergence characteristics, the Karhunen-Loéve method is most suitable for simulating smooth fields with ‘gaussian’ shaped covariance functions. Practical applications of Karhunen-Loéve simulations can be improved by spatial interpolation of the eigenfunctions. In this paper, we suggest interpolation by kriging and limits for reproduction of the predefined covariance functions are evaluated.  相似文献   

Interactive behavior of soil–pile-superstructure system in transient state to liquefaction by means of large shake table tests     

Shintaro Yao  Koichi Kobayashi  Nozomu Yoshida  Hiroshi Matsuo 《Soil Dynamics and Earthquake Engineering》2004,24(5):572-409

Shaking table tests were conducted by means of a large-scale laminar box with 4 m in length, 2 m in width and 2 m in height in order to investigate behavior of a soil-pile-superstructure system in liquefiable ground. A model two-storey structure, supported by a pile group, was set in a saturated sand deposit, and subjected to a sinusoidal base motion with increasing amplitude. Discussions are focused on the transient behavior until soil liquefaction occurs. Main interests are characteristics of springs used in a sway-rocking model and a multi-freedom lumped mass (MFLM) model that are frequently used in soil–pile interaction analysis. The spring constant in the sway-rocking model is represented by restoring force characteristics at the pile head, and that in the MFLM system is represented by an interaction spring connecting the pile to the free field. The transient state prior to soil liquefaction is shown to be important in the design of a pile because dynamic earth pressure shows peak response in this state. The reduction of the stiffness due to excess porewater generation and strain dependent nonlinear behavior is evaluated.  相似文献   

Structure and tectonics of convergent plate margins     

Aleš Špi?ák  Ond?ej ?adek  E.Robert Engdahl 《Physics of the Earth and Planetary Interiors》2004,141(4):241

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Influence of the zone of weakness on dip angle and shear heating of subducted slabs     

Martin Kuka?ka  Ctirad Matyska 《Physics of the Earth and Planetary Interiors》2004,141(4):243-252

We study the importance of the zones of weakness and the pattern of downgoing flow in steady-state models of subducting lithosphere, which interacts mechanically and thermally with the ambient mantle. The non-linear system of governing equations consists of (i) the momentum equation in stream function formulation and (ii) the steady-state heat transfer equation including conduction and advection of heat and dissipation. A finite element method has been applied to this system. We consider the viscosity to be a non-linear function of both the temperature and the stream function. In steady-state two-dimensional (2D) flow, the stream function isolines follow material trajectories. They are used to follow the top of the subducting slab, which because of its possible increase in water content, is assumed to have a lower viscosity. The zone of weakness has been thus obtained in the self-consistent fashion since the stream function as well as the temperature are the output from our modeling and no a priori assumptions about the shape of the bending lithosphere are taken into account. It was shown that several orders decrease of viscosity in the zone of weakness is required to obtain the dip angle of about 45°. If the decrease of viscosity is not sufficient enough, the subducted slab either sinks almost vertically or does not exhibit a plate-like behavior. We have also demonstrated that shear heating can unrealistically increase at the zone of weakness for fast subductions if decrease of viscosity is underestimated.  相似文献   

Strain field measurements of rubber by image analysis and design criteria for laminated rubber bearings (LRB)     

Chamindalal Sujeewa Lewangamage  Masato Abe  Yozo Fujino  Junji Yoshida 《地震工程与结构动力学》2004,33(4):445-464

Although seismic isolation rubber bearings in bridges and buildings have proven to be a very effective passive method for reducing earthquake‐induced forces, a detailed mechanical modeling of the rubber that is used in bearings under large strains has not been established. Therefore, a 3D model of failure behavior and the design criteria for the safety evaluation of seismic isolation bearings have not yet been developed. This paper presents: (1) correlation‐based template‐matching algorithms to measure large strain fields of continua; (2) a failure criterion for rubber; and (3) the design criteria for the safety evaluation of laminated algorithms, data‐validation algorithms were developed and implemented to eliminate possible unrealistic displacement vectors present in the measured displacement field. The algorithms were successfully employed in the strain field measurement of LRB and rubber materials that are subjected to failure. The measured local strains for rubber material at failure were used to develop a failure criterion for rubber. The validity of the proposed criterion was evaluated by applying it to the LRB; the criterion was introduced into a 3D finite element model of LRB, compared with the experimental results of bearings failure, and verified. Finally, design criteria are proposed for LRB for the safety evaluation. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献