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101.
Tommaso Carlà Renato Macciotta Michael Hendry Derek Martin Tom Edwards Trevor Evans Paolo Farina Emanuele Intrieri Nicola Casagli 《Landslides》2018,15(3):489-505
The 10-mile Slide is contained within an ancient earthflow located in British Columbia, Canada. The landslide has been moving slowly for over 40 years, requiring regular maintenance work along where a highway and a railway track cross the sliding mass. Since 2013, the landslide has shown signs of retrogression. Monitoring prisms were installed on a retaining wall immediately downslope from the railway alignment to monitor the evolution of the retrogression. As of September 2016, cumulative displacements in the horizontal direction approached 4.5 m in the central section of the railway retaining wall. After an initial phase of acceleration, horizontal velocities showed a steadier trend between 3 and 9 mm/day, which was then followed by a second acceleration phase. This paper presents an analysis of the characteristics of the surface displacement vectors measured at the monitoring prisms. Critical insight on the behavior and kinematics of the 10-mile Slide retrogression was gained. An advanced analysis of the trends of inverse velocity plots was also performed to assess the potential for a slope collapse at the 10-mile Slide and to obtain further knowledge on the nature of the sliding surface. 相似文献
102.
Pereira Renato Marques Sanches Wanderley Henderson Silva Delgado Rafael Coll 《Natural Hazards》2022,111(1):333-351
Natural Hazards - Understanding the occurrence of natural disasters in regions where the occurrence is high is very important, and it is known that the occurrence of disasters associated with... 相似文献
103.
Roberto Armellin Pierluigi Di Lizia Renato Zanetti 《Celestial Mechanics and Dynamical Astronomy》2016,125(4):435-450
A method to deal with uncertainties in initial orbit determination (IOD) is presented. This is based on the use of Taylor differential algebra (DA) to nonlinearly map uncertainties from the observation space to the state space. When a minimum set of observations is available, DA is used to expand the solution of the IOD problem in Taylor series with respect to measurement errors. When more observations are available, high order inversion tools are exploited to obtain full state pseudo-observations at a common epoch. The mean and covariance of these pseudo-observations are nonlinearly computed by evaluating the expectation of high order Taylor polynomials. Finally, a linear scheme is employed to update the current knowledge of the orbit. Angles-only observations are considered and simplified Keplerian dynamics adopted to ease the explanation. Three test cases of orbit determination of artificial satellites in different orbital regimes are presented to discuss the feature and performances of the proposed methodology. 相似文献
104.
105.
Molinari Daniela Dazzi Susanna Gattai Edoardo Minucci Guido Pesaro Giulia Radice Alessio Vacondio Renato 《Natural Hazards》2021,108(3):3061-3084
Natural Hazards - This paper shows a detailed, advanced procedure to implement cost–benefit analyses (CBAs) in order to assess the effectiveness of flood mitigation measures. The town of Lodi... 相似文献
106.
When performing the seismic risk assessment of new or existing buildings, the definition of compact indexes able to measure the damaging and safety level of structures is essential, also in view of the economic considerations on buildings rehabilitation. This paper proposes two series of indexes, named, respectively, Global Damage Indexes (GDIs), which are representative of the overall structure performance, and Section Damage Indexes (SDIs), which assess the conditions of reinforced concrete (RC) beam‐column sections. Such indexes are evaluated by means of an efficient numerical model able to perform nonlinear analyses of the RC frame, based on the continuum damage mechanics theory and fiber approach. An improvement of a two‐parameter damage model for concrete, developed by some of the authors, which guarantees a better correlation between the Local Damage Indexes (LDIs) and the material's mechanical characteristics, is also presented. For the reinforcement, a specific LDI, named ‘steel damage index’, which takes into account the plastic strain development and the bar buckling effect, is proposed. The numerical model has been employed to simulate several experimental tests, in order to verify the accuracy of the proposed approach in predicting the RC member's behavior. Nonlinear static and dynamic analyses of two RC frames are carried out. The robustness of the method, as well as the effectiveness of the GDIs in assessing the structural conditions, are demonstrated here. Finally, comparisons between the evolution of GDIs and the achievement of the performance levels as proposed in FEMA 356 are reported. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
107.
Francine A. Kalas Renato S. Carreira Stephen A. Macko Angela L. R. Wagener 《Continental Shelf Research》2009
The present work aimed at studying the origin of particulate organic matter in Guanabara Bay and in some rivers of the Guanabara basin by using elemental composition, isotopic ratios (δ13C and δ15N) and molecular markers (sterols) in samples collected in two periods (winter and summer). Elemental and isotopic compositions were determined by dry combustion and mass spectrometry, respectively, while sterols were investigated by GC–FID and GC–MS. Higher sterol concentrations were present in the north-western part of the bay in winter (5.10–23.5 μg L–1). The high abundance of algal sterols (26–57% of total sterols), the elemental composition (C/N=6–8) and the isotopic signatures (δ13C=−21.3‰ to −15.1‰ and δ15N=+7.3‰ to +11.1‰) suggested the predominance of autochthonous organic matter, as expected for an eutrophic bay, although seasonal variation in phytoplankton activity was observed. Coprostanol concentration (fecal sterol) was at least one order of magnitude higher in the particulate material from fluvial samples (4.65–55.98 μg L–1) than in the bay waters (<0.33 μg L–1). This could be ascribed to a combination of factors including efficient particle removal to sediments in the estuarine transition zone, dilution with bay water and bacterial degradation during particle transport in the water column. 相似文献
108.
Mount Etna volcano was shaken during the summer 2001 by one of the most singular eruptive episodes of the last centuries.
For about 3 weeks, several eruptive fractures developed, emitting lava flows and tephra that significantly modified the landscape
of the southern flank of the volcano. This event stimulated the attention of the scientific community especially for the simultaneous
emission of petrologically distinct magmas, recognized as coming from different segments of the plumbing system. A stratigraphically
controlled sampling of tephra layers was performed at the most active vents of the eruption, in particular at the 2,100 m
(CAL) and at the 2,550 m (LAG) scoria cones. Detailed scanning electron microscope and energy dispersive x-ray spectrometer
(SEM-EDS) analyses performed on glasses found in tephra and comparison with lava whole rock compositions indicate an anomalous
increase in Ti, Fe, P, and particularly of K and Cl in the upper layers of the LAG sequence. Mass balance and thermodynamic
calculations have shown that this enrichment cannot be accounted for by “classical” differentiation processes, such as crystal
fractionation and magma mixing. The analysis of petrological features of the magmas involved in the event, integrated with
the volcanological evolution, has evidenced the role played by volatiles in controlling the magmatic evolution within the
crustal portion of the plumbing system. Volatiles, constituted of H2O, CO2, and Cl-complexes, originated from a deeply seated magma body (DBM). Their upward migration occurred through a fracture network
possibly developed by the seismic swarms during the period preceding the event. In the upper portion of the plumbing system,
a shallower residing magma body (ABT) had chemical and physical conditions to receive migrating volatiles, which hence dissolved
the mobilized elements producing the observed selective enrichment. This volatile-induced differentiation involved exclusively
the lowest erupted portion of the ABT magma due to the low velocity of volatiles diffusion within a crystallizing magma body
and/or to the short time between volatiles migration and the onset of the eruption. Furthermore, the increased amount of volatiles
in this level of the chamber strongly affected the eruptive behavior. In fact, the emission of these products at the LAG vent,
towards the end of the eruption, modified the eruptive style from classical strombolian to strongly explosive. 相似文献
109.
Geomorphic influence on small glacier response to post‐Little Ice Age climate warming: Julian Alps,Europe
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Renato R. Colucci 《地球表面变化过程与地形》2016,41(9):1227-1240
The evolution of glaciers and ice patches, as well as the equilibrium‐line altitude (ELA) since the Little Ice Age (LIA) maximum were investigated in the Julian Alps (south‐eastern European Alps) including ice masses that were previously unreported. Twenty‐three permanent firn and ice bodies have been recognized in the 1853 km2 of this alpine sector, covering a total area in 2012 of 0.385 km2, about one‐fifth of the area covered during the LIA (2.350 km2). These features were classified as very small glaciers, glacierets or ice patches, with major contribution to the mass balance from avalanches and wind‐blown snow. Localized snow accumulation is also enhanced in the area due to the irregular karst topography. The ice masses in the region are at the lowest elevations of any glaciers in the Alpine Chain, and are characterized by low dynamics. The ELAs of the two major LIA glaciers (Canin and Triglav) have been established at 2275 ± 10 m and 2486 ± 10 m, respectively, by considering the reconstructed area and digital elevation model (DEM) and using an accumulation area ratio (AAR) of 0.44 ± 0.07, typical of small cirque glaciers. Changes in the ELA and glaciers extension indicate a decoupling from climate. This is most evident in the smallest avalanche‐dominated ice bodies, which are currently controlled mainly by precipitation. The damming effect of moraine ridges and pronival ramparts at the snout of small ice bodies in the Julian Alps represents a further geomorphological control on the evolution of such ice masses, which seem to be resilient to recent climate warming instead of rapidly disappearing as should be expected. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
110.
In this paper, we discuss high‐resolution coherence functions for the estimation of the stacking parameters in seismic signal processing. We focus on the Multiple Signal Classification which uses the eigendecomposition of the seismic data to measure the coherence along stacking curves. This algorithm can outperform the traditional semblance in cases of close or interfering reflections, generating a sharper velocity spectrum. Our main contribution is to propose complexity‐reducing strategies for its implementation to make it a feasible alternative to semblance. First, we show how to compute the multiple signal classification spectrum based on the eigendecomposition of the temporal correlation matrix of the seismic data. This matrix has a lower order than the spatial correlation used by other methods, so computing its eigendecomposition is simpler. Then we show how to compute its coherence measure in terms of the signal subspace of seismic data. This further reduces the computational cost as we now have to compute fewer eigenvectors than those required by the noise subspace currently used in the literature. Furthermore, we show how these eigenvectors can be computed with the low‐complexity power method. As a result of these simplifications, we show that the complexity of computing the multiple signal classification velocity spectrum is only about three times greater than semblance. Also, we propose a new normalization function to deal with the high dynamic range of the velocity spectrum. Numerical examples with synthetic and real seismic data indicate that the proposed approach provides stacking parameters with better resolution than conventional semblance, at an affordable computational cost. 相似文献