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101.
On the treatment of uncertainties in the development of fragility functions for earthquake loss estimation of building portfolios 下载免费PDF全文
State‐of‐the‐art methods for the assessment of building fragility consider the structural capacity and seismic demand variability in the estimation of the probability of exceeding different damage states. However, questions remain regarding the appropriate treatment of such sources of uncertainty from a statistical significance perspective. In this study, material, geometrical and mechanical properties of a number of building classes are simulated by means of a Monte Carlo sampling process in which the statistical distribution of the aforementioned parameters is taken into consideration. Record selection is performed in accordance with hazard‐consistent distributions of a comprehensive set of intensity measures, and issues related with sufficiency, efficiency, predictability and scaling robustness are addressed. Based on the appraised minimum number of ground motion records required to achieve statistically meaningful estimates of response variability conditioned on different levels of seismic intensity, the concept of conditional fragility functions is presented. These functions translate the probability of exceeding a set of damage states as a function of a secondary sufficient intensity measure, when records are selected and scaled for a particular level of primary seismic intensity parameter. It is demonstrated that this process allows a hazard‐consistent and statistically meaningful representation of uncertainty and correlation in the estimation of intensity‐dependent damage exceedance probabilities. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
102.
Gervásio Annes Degrazia Umberto Rizza Franciano Scremin Puhales Antônio Gledson Goulart Jonas Carvalho Guilherme Sausen Welter Edson Pereira Marques Filho 《Boundary-Layer Meteorology》2009,131(2):277-292
A variable vertical mesh spacing for large-eddy simulation (LES) models in a convective boundary layer (CBL) is proposed.
The argument is based on the fact that in the vertical direction the turbulence near the surface in a CBL is inhomogeneous
and therefore the subfilter-scale effects depend on the relative location between the spectral peak of the vertical velocity
and the filter cut-off wavelength. From the physical point of view, this lack of homogeneity makes the vertical mesh spacing
the principal length scale and, as a consequence, the LES filter cut-off wavenumber is expressed in terms of this characteristic
length scale. Assuming that the inertial subrange initial frequency is equal to the LES filter cut-off frequency and employing
fitting expressions that describe the observed convective turbulent energy one-dimensional spectra, it is feasible to derive
a relation to calculate the variable vertical mesh spacing. The incorporation of this variable vertical grid within a LES
model shows that both the mean quantities (and their gradients) and the turbulent statistics quantities are well described
near to the ground level, where the LES predictions are known to be a challenging task. 相似文献
103.
Comparative energetics of ERA-40, JRA-25 and NCEP-R2 reanalysis, in the wave number domain 总被引:1,自引:0,他引:1
The European Centre for Medium-Range Weather Forecasts 40-year Reanalysis (ERA-40), the Japan Meteorological Agency and Central Research Institute of Electric Power Industry 25-year Reanalysis (JRA-25), and the National Centers for Environmental Prediction and Department of Energy AMIP-II Reanalysis (NCEP-R2) are intercompared through a global energetics analysis for all seasons.Overall, the Lorenz energy cycle is consistent among the three datasets. The flow of energy and the peaks and slopes in the spectra of the various components agree between the three reanalysis. Additionally, the temporal variability of the energy cycle terms shows consistency between the three reanalysis. Most differences between the three reanalysis are related to the magnitudes of energy forms and energy conversion/transfer rates at each wave number, generally following the relation ERA−40>JRA−25>NCEP−R2, and mainly located in the Southern Hemisphere. The best agreement between the three datasets is found for northern winter. Differences between the three datasets are greater for the other seasons, being greatest for northern summer. In general, these discrepancies are fairly modest, being likely due to the different model biases and resolutions, and the different data assimilation methods used by the respective reanalysis systems. The energetics of the three reanalysis become closer to each other in more recent years, which is likely due to the increase in the number of observations assimilated in the reanalysis.The NCEP-R2 reanalysis spectrum is smoother than those of ERA-40 and JRA-25, likely due to filtering and to its lower resolution model. The spectra show a rapid decrease for short waves in NCEP-R2 (n=36) and ERA-40 (n=63), as a consequence of filtering. The energy source in the nonlinear wave–wave interactions of kinetic energy, L(n), has a narrower spectral range in NCEP-R2 than in the other datasets. Energetics from the newer JRA-25 reanalysis is generally closer to that of ERA-40, with some exceptions as is the case of zonal–wave interactions of kinetic energy, M(n), for synoptic waves, or for eddy available potential energy, AE, in the lower troposphere, for which JRA-25 is closer to NCEP-R2. 相似文献
104.
Medium-resolution infrared (1–2.5 μm; Δλ/λ ∽ 0.05) photometry of Triton, Titania, and Hyperion and medium-resolution (1.5–2.4 μm; Δλ/λ ? 0.01) spectroscopy of Triton are presented. Hyperion and Titania have spectra roughly similar to the laboratory spectrum of water frost, while the spectrum of Triton is inconsistent with the spectra of frosts likely to be major surface constituents. 相似文献
105.
106.
J. Marques Monteiro F. Santos R. Graça R. Castro L. Aires-Barros L. Mendes Victor 《Hydrogeology Journal》2001,9(6):584-596
The Vilarelho da Raia-Chaves region, located in northern Portugal adjacent to the Spanish border, is characterized by both
hot and cold CO2-rich mineral waters issuing from springs and drilled wells. The present paper updates the conceptual circulation model of
the Vilarelho da Raia cold CO2-rich mineral waters. Vilarelho da Raia mineral waters, dominated by Na and HCO3 ions, have formed mainly by interaction with CO2 of deep-seated mantle origin. The δ
18O, δ
2H and 3H values indicate that these waters are the result of meteoric waters infiltrating into Larouco Mountain, NW of Vilarelho
da Raia, circulating at shallow depths in granitic rocks and moving into Vilarelho da Raia area. The conceptual geochemical
and geophysical circulation model indicates that the hot and cold CO2-rich mineral waters of Chaves (76 °C) and Vilarelho da Raia (17 °C) should be considered manifestations of similar but not
the same geohydrological systems.
Electronic Publication 相似文献
107.
108.
Gabriel Kuhn Shiraj Khan Auroop R. Ganguly Marcia L. Branstetter 《Advances in water resources》2007,30(12):2401-2423
A quantification of the spatio-temporal dependence among precipitation extremes is important for investigating the properties of intense storms as well as flood or flash-flood related hazards. Extreme value theory has been widely applied to the hydrologic sciences and hydraulic engineering. However, rigorous approaches to quantify dependence structures among extreme values in space and time have not been reported in the literature. Previous researchers have quantified the dependence among extreme values through the concept of (pairwise bivariate) tail dependence coefficients. For estimation of the tail dependence coefficients, we apply a recently developed method [Kuhn G. On dependence and extremes. PhD thesis (Advisor: C. Klüppelberg), Munich University of Technology, 2006] which utilized the multivariate tail dependence function of a subclass of elliptical copulas. This study extends the previous approach in the context of space and time by considering pairs of spatial grids in South America and quantifying the dependence among precipitation extremes based on the time series at each spatial grid. In addition, Kendall’s τ is used to estimate the pairwise copula correlation (for an elliptical copula) of precipitation between all grids in South America. The geospatial–temporal dependence measures are applied to precipitation observations from 1940 to 2005 as well as simulations from the Community Climate System Model version 3 (CCSM3) for 1940–2099. New insights are obtained regarding the spatio-temporal dependence structures for precipitation over South America both with regard to correlation as well as tail dependence. 相似文献
109.
110.
Salt marsh ecosystems provide many critical ecological functions, yet they are subject to considerable disturbance ranging from direct human alteration to increased inundation due to climate change. We assessed emergent salt marsh plant characteristics in the Tuckerton Peninsula, a large expanse (~ 2000 ha) of highly inundated habitat along the southern New Jersey coast, USA. Key salt marsh plant parameters were monitored in the heavily grid-ditched northern segment, Open Marsh Water Management (OMWM) altered central segment, and the shoreline altered southern segment of the peninsula in the summer months of 2011 and 2013. Plant species composition and three metrics of abundance and structure (maximum canopy height, percent areal cover, and shoot density) were examined among marsh segments, along transects within segments, seasonally by month and between years. Despite seasonal or annual variability, the northern segment of the marsh differed in plant species composition from the central and southern segments. This difference was partly due to greater percent areal cover in the northern segment of upper marsh species such as Spartina patens and Distichlis spicata. S. patens also exhibited higher shoot densities in the northern segment than the central segment. Despite the higher abundance of upper marsh species, marsh surface elevations were lower in the northern segment than in the central or southern segments, suggesting the influence of altered hydrology due to human activities. Understanding current variation in the emergent salt marsh vegetation along the peninsula will help inform future habitat change in other coastal wetlands of New Jersey and the mid-Atlantic region subject to natural and anthropogenic drivers. 相似文献