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61.
In this paper, the application of an efficient, transparent and accurate kinematic-cyclic constitutive model based on the fuzzy-set concepts and incremental plasticity theory is presented to show its capability in modeling cyclic mobility of saturated granular soil. The nature and kinematic mechanism of the membership functions in the fuzzy-set constitutive model are illustrated. The model’s capability of modeling soil dilatancy is investigated. Important features of volume change and pore water pressure build-up related to soil cyclic mobility are captured. The formulation of the proposed model is relatively simple and it can be readily implemented in finite element codes. The enhanced fuzzy-set model is capable of simulating ground motion problems particularly related to cyclic mobility, soil liquefaction, and spreading behavior. 相似文献
62.
Black dimensional stones: geology, technical properties and deposit characterization of the dolerites from Uruguay 总被引:1,自引:1,他引:0
Manuela Morales Demarco Pedro Oyhantçabal Karl-Jochen Stein Siegfried Siegesmund 《Environmental Earth Sciences》2011,63(7-8):1879-1909
Dimensional stones with a black color occupy a prominent place on the international market. Uruguayan dolerite dikes of andesitic and andesitic–basaltic composition are mined for commercial blocks of black dimensional stones. A total of 16 dikes of both compositions were studied and samples collected for geochemical and petrographical analysis. Color measurements were performed on different black dimensional stones in order to compare them with the Uruguayan dolerites. Samples of the two commercial varieties (Absolute Black and Moderate Black) were obtained for petrophysical analysis (e.g. density, porosity, uniaxial compressive strength, tensile strength, etc.). Detailed structural analyses were performed in several quarries. Geochemistry and petrography determines the intensity of the black color. The Uruguayan dolerite Absolute Black is the darkest black dimensional stone analyzed in this study. The petrophysical properties of Uruguayan dolerites make them one of the highest quality black dimensional stones. Structural analyses show that five joint sets have been recognized: two sub-vertical joints, one horizontal and two diagonal. These joint sets are one of the most important factors that control the deposits, since they control the block size distribution and the amount of waste material. 相似文献
63.
Noriko T. Kita Qing‐Zhu Yin Glenn J. MacPherson Takayuki Ushikubo Benjamin Jacobsen Kazuhide Nagashima Erika Kurahashi Alexander N. Krot Stein B. Jacobsen 《Meteoritics & planetary science》2013,48(8):1383-1400
High‐precision bulk aluminum‐magnesium isotope measurements of calcium‐aluminum‐rich inclusions (CAIs) from CV carbonaceous chondrites in several laboratories define a bulk 26Al‐26Mg isochron with an inferred initial 26Al/27Al ratio of approximately 5.25 × 10?5, named the canonical ratio. Nonigneous CV CAIs yield well‐defined internal 26Al‐26Mg isochrons consistent with the canonical value. These observations indicate that the canonical 26Al/27Al ratio records initial Al/Mg fractionation by evaporation and condensation in the CV CAI‐forming region. The internal isochrons of igneous CV CAIs show a range of inferred initial 26Al/27Al ratios, (4.2–5.2) × 10?5, indicating that CAI melting continued for at least 0.2 Ma after formation of their precursors. A similar range of initial 26Al/27Al ratios is also obtained from the internal isochrons of many CAIs (igneous and nonigneous) in other groups of carbonaceous chondrites. Some CAIs and refractory grains (corundum and hibonite) from unmetamorphosed or weakly metamorphosed chondrites, including CVs, are significantly depleted in 26Al. At least some of these refractory objects may have formed prior to injection of 26Al into the protosolar molecular cloud and its subsequent homogenization in the protoplanetary disk. Bulk aluminum and magnesium‐isotope measurements of various types of chondrites plot along the bulk CV CAI isochron, suggesting homogeneous distribution of 26Al and magnesium isotopes in the protoplanetary disk after an epoch of CAI formation. The inferred initial 26Al/27Al ratios of chondrules indicate that most chondrules formed 1–3 Ma after CAIs with the canonical 26Al/27Al ratio. 相似文献
64.
J. Stein E. Richard J. P. Lafore J. P. Pinty N. Asencio S. Cosma 《Meteorology and Atmospheric Physics》2000,72(2-4):203-221
Summary ?Simulations of two heavy rainfall events south of the Alps have been conducted with a non-hydrostatic model at horizontal
resolutions ranging from 40 to 2.5 km. Emphasis is placed on the assessment of two recent model developments: a detailed explicit
mixed phase microphysical scheme and a two-way interactive grid nesting method. In the high-resolution simulations, the impact
of the ice phase was found to be quite substantial, accelerating the propagation of the surface front and modifying the spatial
distribution of the rainfall. Simulations carried out with two-way interactive grid nesting yielded more realistic overall
precipitation patterns, particularly at the finest horizontal resolution.
Received March 22, 1999/Revised June 28, 1999 相似文献
65.
Ruediger Stein 《International Journal of Earth Sciences》2000,89(3):447-449
66.
Towards global space geodetic mapping of the dynamic deformation field after great earthquakes
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GPS systems can be used as seismometers by sampling ground positions to detect travelling seismic waves. Data from dense geodetic networks near large earthquakes have been used to improve magnitude estimates, for tsunami warning, and to better understand the rupture processes. Here, we present 1 Hz GPS records of the March 11th, 2011, Mw = 9.0 Tohoku earthquake at unprecedented teleseismic distances. The spatial and temporal variations of the three‐dimensional GPS displacement vector field show various body waves, Love and Rayleigh surface waves along the direct path, and Love waves from the more than 31 000 km long major arc path. These results suggest that seismic wavefields can be mapped at teleseismic distances globally using space geodesy and could thus be used for source and structural studies. Data from numerous real‐time kinematic GPS networks could be combined to show the displacement field, giving unparalleled views of Earth's response to large earthquakes. 相似文献
67.
ALAN M. Stein 《Basin Research》1988,1(2):107-119
Abstract The Hebridean basins are part of a compartmentalized half-graben developed in the hanging wall of the partially reactivated Outer Isles Fault. The importance of geological inheritance in the development of these basins can be demonstrated clearly using the widespread exposure of metamorphic basement around the basin margins. The basement structures have been analysed using thematically mapped Landsat images in conjunction with selective field studies. Results of such studies have been integrated with maps generated from the interpretation of offshore multichannel seismic reflection profiles to produce an architectural framework for basin development.
It can be demonstrated that the principal basement faults originated in the early Proterozoic as mid-crustal shear zones and that they have subsequently been partially reactivated during post-Caledonian basin development beginning in the Carboniferous and probably also during an earlier period of basin development in the late Proterozoic (the Torridonian). It is the geometry of the pre-existing basement structures that has controlled the three-dimensional shape of the sedimentary basins and the spatial and temporal distribution of the basin fill. 相似文献
It can be demonstrated that the principal basement faults originated in the early Proterozoic as mid-crustal shear zones and that they have subsequently been partially reactivated during post-Caledonian basin development beginning in the Carboniferous and probably also during an earlier period of basin development in the late Proterozoic (the Torridonian). It is the geometry of the pre-existing basement structures that has controlled the three-dimensional shape of the sedimentary basins and the spatial and temporal distribution of the basin fill. 相似文献
68.
A GIS‐based multi‐criteria seismic vulnerability assessment using the integration of granular computing rule extraction and artificial neural networks
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This study proposes multi‐criteria group decision‐making to address seismic physical vulnerability assessment. Granular computing rule extraction is combined with a feed forward artificial neural network to form a classifier capable of training a neural network on the basis of the rules provided by granular computing. It provides a transparent structure despite the traditional multi‐layer neural networks. It also allows the classifier to be applied on a set of rules for each incoming pattern. Drawbacks of original granular computing (GrC) are covered, where some input patterns remained unclassified. The study was applied to classify seismic vulnerability of the statistical units of the city of Tehran, Iran. Slope, seismic intensity, height and age of the buildings were effective parameters. Experts ranked 150 randomly selected sample statistical units with respect to their degree of seismic physical vulnerability. Inconsistency of the experts' judgments was investigated using the induced ordered weighted averaging (IOWA) operator. Fifty‐five classification rules were extracted on which a neural network was based. An overall accuracy of 88%, κ = 0.85 and R2 = 0.89 was achieved. A comparison with previously implemented methodologies proved the proposed method to be the most accurate solution to the seismic physical vulnerability of Tehran. 相似文献
69.
Igneous formations associated with massive sulphide deposits in the Iberian Pyrite Belt (IPB) are essentially composed of
basic lavas and dolerites, and dacitic to rhyolitic volcanites; intermediate lavas are subordinate. The basic rocks show variable
geochemical characteristics: lavas and dolerites comparable to recent within-plate alkaline basalts seem restricted to the
western and southern parts of the IPB, whereas basic rocks comparable to continental tholeiites or arc-related basalts occur
across the whole belt. The felsic rocks are classified as calc-alkaline and belong to the “low-Al2O3 and high-Yb type”. At given SiO2, Al2O3 and TiO2 contents, they show variable Zr, Nb, and HREE contents. Heavy-rare-earth element fractionation decreases from the dacites
to the rhyolites ([Gd/Yb]N ∼ 1), whereas the negative Eu-anomaly becomes more pronounced. The characteristics of the rhyolites are typical of sulphide-fertile
volcanic packages. Trace-element modelling suggests that the felsic rocks evolved from a dacitic parent magma through fractional
crystallization of hornblende and plagioclase. Partial melting of an amphibolite protolith, which appears as the most probable
model for the origin of this dacitic magma, requires a high T/P gradient in the crust. The occurrence of alkaline basalts and continental tholeiites is consistent with formation of the
IPB in a tensional tectonic setting. However, the associated island-arc tholeiites suggest a location in a domain of plate
convergence. Emplacement in a fore-arc basin over a recently accreted crustal segment is envisaged as a possible hypothesis
to account for the geological and petrological constraints. A high geothermal gradient and eruption in a submarine tensional
basin could have been two key ingredients for the development of massive sulphide deposits within the IPB.
Received: 3 March 1996 / Accepted: 7 April 1997 相似文献
Resumen (translated by E. Pascual) Las formaciones ígneas asociadas con los depósitos de sulfuros masivos de la Faja Pirítica Ibérica (IPB) se componen esencialmente de doleritas y lavas básicas y de rocas volcánicas dacíticas a riolíticas; las lavas intermedias son poco abundantes. Las rocas básicas muestran caracteres geoquímicos variables: lavas y doleritas comparables a basaltos alcalinos intraplaca recientes parecen hasta ahora restringidos a las partes W y S de la IPB, mientras que rocas básicas de caracteres comparables a las de toleítas continentales o basaltos relacionados con arcos aparecen en toda la zona. Las rocas ácidas se clasifican como calcoalcalinas del tipo “low-Al2O3, high-Yb”. Para un contenido dado en SiO2, Al2O3 y TiO2, muestran contenidos variables en Zr, Nb y REE. El contenido en tierras raras pesadas decrece de dacitas a riolitas ([Gd/Yb]N ∼ 1), al tiempo que la anomalía de Eu se hace más pronunciada. La modelización de elementos trazas sugiere que las rocas evolucionaron a partir de un magma parental dacítico mediante cristalización fraccionada de hornblenda y plagioclasa. La fusión parcial de un protolito anfibolítico, que parece el modelo más plausible para el origen del magma dacítico, requiere un elevado gradiente T/P en la corteza. La existencia de basaltos alcalinos y de toleítas continentales es congruente con la formación de la IPB en un entorno tectónico distensivo. El emplazamiento en una cuenca “fore-arc”, en un segmento cortical de reciente acreción, se contempla como una hipótesis posible para explicar los caracteres geológicos y petrológicos. Un alto gradiente térmico, junto con la erupción en una cuenca submarina extensional, pueden haber sido los dos ingredientes clave en el desarrollo de los depósitos de sulfuros masivos en la IPB.
Received: 3 March 1996 / Accepted: 7 April 1997 相似文献
70.
Universal cokriging is used to obtain predictions when dealing with multivariate random functions. An important type of nonstationarity is defined in terms of multivariate random functions with increments which are stationary of orderk. The covariance between increments of different variables is modeled by means of the pseudo-cross-covariance function. Criteria are formulated to which the parameters of pseudo-cross-covariance functions must comply so as to ensure positive-definiteness. Cokriging equations and the induced cokriging equations are given. The study is illustrated by an example from soil science. 相似文献