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71.
72.
Estimation procedures for exchangeable Marshall copulas with hydrological application 总被引:1,自引:1,他引:0
Fabrizio Durante Ostap Okhrin 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(1):205-226
Complex phenomena in environmental sciences can be conveniently represented by several inter-dependent random variables. In order to describe such situations, copula-based models have been studied during the last year. In this paper, we consider a novel family of bivariate copulas, called exchangeable Marshall copulas. Such copulas describe both positive and (upper) tail association between random variables. Specifically, inference procedures for the family of exchangeable Marshall copulas are introduced, based on the estimation of their (univariate) generator. Moreover, the performance of the proposed methodologies is shown in a simulation study. Finally, an illustration describes how the proposed procedures can be useful in a hydrological application. 相似文献
73.
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75.
Infrastructure owners and operators, or governmental agencies, need rapid screening tools to prioritize detailed risk assessment and retrofit resources allocation. This paper provides one such tool, for use by highway administrations, based on Bayesian belief network (BBN) and aimed at replacing so‐called generic or typological seismic fragility functions for reinforced concrete girder bridges. Resources for detailed assessments should be allocated to bridges with highest consequence of damage, for which site hazard, bridge fragility, and traffic data are needed. The proposed BBN based model is used to quantify seismic fragility of bridges based on data that can be obtained by visual inspection and engineering drawings. Results show that the predicted fragilities are of sufficient accuracy for establishing relative ranking and prioritizing. While the actual data and seismic hazard employed to train the network (establishing conditional probability tables) refer to the Italian bridge stock, the network structure and engineering judgment can easily be adopted for bridges in different geographical locations. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
76.
77.
Andrea Zanchi Paolo D’Adda Stefano Zanchetta Fabrizio Berra 《Swiss Journal of Geoscience》2012,105(1):19-38
The lateral continuity of the E?CW trending thrust sheets developed within the Lower to Middle Triassic cover of the central Southern Alps (Orobic belt) is disturbed by the occurrence of several N?CS trending transverse zones, such as the poorly known Grem?CVedra Transverse Zone (GVTZ). The GVTZ developed during the emplacement of the up to six S-verging thrust sheets consisting of Lower to Middle Triassic units, occurring immediately south of the Orobic Anticlines. The transverse zone, active during thrust emplacement related to the early Alpine compressions which pre-date the Adamello intrusion, includes three major vertical shear zones, the Grem, Pezzel and Zuccone faults. The major structure of the transverse zone is the dextral Grem fault, forming a deep lateral ramp between thrust sheets 3 and 5. A similar evolution also occurred along the Zuccone and Pezzel faults, which show a left-lateral displacement of syn-thrust folds. The Grem fault was later reactivated as an oblique tear fault during the emplacement of the Orobic Anticlines, due to back-thrusting along out-of-sequence thrust surfaces (Clusone fault). Transpressional deformations along the fault zone are recorded by the rotation of major syn-thrust folds, which also suggest a horizontal offset close to 0.5?km. Records of the first stage of evolution of the Grem fault are better preserved along its northern segment, and structural relationships suggest that it propagated southward and downward in the growing thrust stack. The study of the meso and megascopic structures developed along the GVTZ constrains the evolution of the transverse zone, illustrating the complex deformational phenomena occurring in a transpressional regime. The GVTZ probably reflects the existence of pre-existing tectonic lineaments with a similar orientation. Evidence of pre-existing structures are not preserved in the exposed units, nevertheless the N?CS extensional fault systems that characterize the Norian to Jurassic rifting history of the Lombardian basin are valid candidates. 相似文献
78.
Paola Bordoni John Haines Giuliano Milana Sandro Marcucci Fabrizio Cara Giuseppe Di Giulio 《Bulletin of Earthquake Engineering》2011,9(3):761-781
This is the first part of a study on the seismic response of the L’Aquila city using 2D simulation and experimental data.
We have studied two velocity-depth models with the aim of outlining the behavior of a velocity reversal in the top layer,
which is associated with the stiff Brecce de L’Aquila unit (BrA). In this setting, the SMTH model is topped by a layer with
about 2:1 impedance contrast with the underlying layer while the NORV model has no velocity reversal. We have simulated the
propagation of SH and P-SV wavefields in the range 0–10 Hz for incidence 0°–90°. Earthquake spectral ratios of the horizontal
and vertical components at six sites in L’Aquila downtown are compared to corresponding synthetics spectral ratios. The vertical
component of P-SV synthetics enables us to investigate a remarkable amplification effect seen in the vertical component of
the recorded strong motion. Sites AQ04 and AQ05 are best matched by synthetics from the NORV model while FAQ5 and AQ06 have
a better match with synthetics spectral ratios from the SMTH model. All simulations show this behavior systematically, with
horizontal and near-horizontal incident waves predicting the overall pattern of matches more clearly than vertical and near-vertical
incidence. The model inferences are in agreement with new geological data reporting lateral passages in the top layer from
the stiff BrA to softer sediments. Matches are good in terms of frequency of the first amplification peak and of spectral
amplitude: the horizontal components have spectral ratio peaks predominantly at 0.5 Hz in the simulations and at 0.7 Hz in
the data, both with amplitudes of 4, while the vertical component spectral ratios reach values of 6 at frequencies of about
1 Hz in both data and simulations. The vertical component spectral ratios are very well matched using Rayleigh waves with
incidence at 90°. The NORV model without the velocity reversal predicts spectral ratio peaks for the horizontal components
at frequencies up to 6 Hz. The reversal of velocity acts as a low-pass frequency filter on the horizontal components reducing
the amplification effect of the sediment filled valley. 相似文献
79.
Matteo Alvaro Fernando Cámara M. Chiara Domeneghetti Fabrizio Nestola Vittorio Tazzoli 《Contributions to Mineralogy and Petrology》2011,162(3):599-613
A natural Ca-poor pigeonite (Wo6En76Fs18) from the ureilite meteorite sample PCA82506-3, free of exsolved augite, was studied by in situ high-temperature single-crystal
X-ray diffraction. The sample, monoclinic P21/c, was annealed up to 1,093°C to induce a phase transition from P21/c to C2/c symmetry. The variation with increasing temperature of the lattice parameters and of the intensity of the b-type reflections (h + k = 2n + 1, present only in the P21/c phase) showed a displacive phase transition P21/c to C2/c at a transition temperature T
Tr = 944°C, first order in character. The Fe–Mg exchange kinetics was studied by ex situ single-crystal X-ray diffraction in
a range of temperatures between the closure temperature of the Fe–Mg exchange reaction and the transition temperature. Isothermal
disordering annealing experiments, using the IW buffer, were performed on three crystals at 790, 840 and 865°C. Linear regression
of ln k
D versus 1/T yielded the following equation:
ln k\textD = - 3717( ±416)/T(K) + 1.290( ±0.378); (R2 = 0.988) \ln \,k_{\text{D}} = - 3717( \pm 416)/T(K) + 1.290( \pm 0.378);\quad (R^{2} = 0.988) . The closure temperature (T
c) calculated using this equation was ∼740(±30)°C. Analysis of the kinetic data carried out taking into account the e.s.d.'s
of the atomic fractions used to define the Fe–Mg degree of order, performed according to Mueller’s model, allowed us to retrieve
the disordering rate constants C
0
K
dis+ for all three temperatures yielding the following Arrhenius relation:
ln( C0 K\textdis + ) = ln K0 - Q/(RT) = 20.99( ±3.74) - 26406( ±4165)/T(K); (R2 = 0.988) \ln \left( {C_{0} K_{\text{dis}}^{ + } } \right) = \ln \,K_{0} - Q/(RT) = 20.99( \pm 3.74) - 26406( \pm 4165)/T(K);\quad (R^{2} = 0.988) . An activation energy of 52.5(±4) kcal/mol for the Fe–Mg exchange process was obtained. The above relation was used to calculate
the following Arrhenius relation modified as a function of X
Fe (in the range of X
Fe = 0.20–0.50):
ln( C0 K\textdis + ) = (21.185 - 1.47X\textFe ) - \frac(27267 - 4170X\textFe )T(K) \ln \left( {C_{0} K_{\text{dis}}^{ + } } \right) = (21.185 - 1.47X_{\text{Fe}} ) - {\frac{{(27267 - 4170X_{\text{Fe}} )}}{T(K)}} . The cooling time constant, η = 6 × 10−1 K−1 year−1 calculated on the PCA82506-3 sample, provided a cooling rate of the order of 1°C/min consistent with the extremely fast late
cooling history of the ureilite parent body after impact excavation. 相似文献
80.
Paolo D’Adda Andrea Zanchi Maria Bergomi Fabrizio Berra Marco G. Malusà Annalisa Tunesi Stefano Zanchetta 《International Journal of Earth Sciences》2011,100(5):1095-1113
The Triassic succession of the central Southern Alps (Italy) is stacked into several units bounded by south-verging low-angle
thrust faults, which are related to two successive steps of crustal shortening. The thrust surfaces are cut by high-angle
extensional and strike-slip faults, which controlled the emplacement of hypabissal magmatic intrusions that post-date thrusts
motions. Intrusion ages based on SHRIMP U–Pb zircon dating span between 42 ± 1 and 39 ± 1 Ma, suggesting close time relationships
with the earliest Adamello intrusion stages and, more in general, with the widespread calc-alkaline magmatism described in
the Southern Alps. Fission-track ages of magmatic apatites are indistinguishable from U–Pb crystallization ages of zircons,
suggesting that the intrusion occurred in country rocks already exhumed above the partial annealing zone of apatite (depth < 2–4 km).
These data indicate that the central Southern Alps were already structured and largely exhumed in the Middle Eocene. Although
we describe minor faults affecting magmatic bodies and local reactivations of older structures, no major internal deformations
have occurred in the area after the Bartonian. Neogene deformations were instead concentrated farther south, along the frontal
part of the belt. 相似文献