New applications of the Poisson distribution in micropalaeontology: relationships between environmental variables and the Ammonia tepida distribution in the south‐western Spanish estuaries     

Francisco Ruiz  María Luz Gonzlez‐Regalado  Manuel Abad  Juan Manuel Muoz  Rafael Pino 《地学学报》2007,19(5):367-372

The application of the Poisson regression to the populations of the benthic foraminifer Ammonia tepida collected in three south‐western Spanish estuaries permits to obtain a quantitative approach between some environmental variables and the number of individuals of this species. Although the three general models are unsatisfactory to predict the observed abundance of this micro‐organism, a partial statistical analysis permits to detect quantitatively the impact of each variable. This analysis indicates an increasing abundance from the high‐salt marshes to the subtidal channels and higher densities in those samples subjected to very euryhaline conditions. Increasing sand percentages show negative effects on the A. tepida abundance, whereas the silt contents do not affect significantly to this species and increasing organic carbon percentages have a small positive effect on the A. tepida densities.  相似文献   

Constructed wetlands increase the taxonomic and functional diversity of a degraded floodplain   总被引：1，自引：0，他引：1  

Cecilia Español  Belinda Gallardo  Francisco A. Comín  M. Rosa Pino 《Aquatic Sciences - Research Across Boundaries》2015,77(1):27-44

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STANOVA: a smoothed-ANOVA-based model for spatio-temporal disease mapping     

Francisco Torres-Avilés  Miguel A. Martinez-Beneito 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(1):131-141

Spatio-temporal disease mapping can be viewed as a multivariate disease mapping problem with a given order of the geographic patterns to be studied. As a consequence, some of the techniques in multivariate literature could also be used to build spatio-temporal models. In this paper we propose using the smoothed ANOVA multivariate model for spatio-temporal problems. Under our approach the time trend for each geographic unit is modeled parametrically, projecting it on a preset orthogonal basis of functions (the contrasts in the smoothed ANOVA nomenclature), while the coefficients of these projections are considered to be spatially dependent random effects. Despite the parametric temporal nature of our proposal, we show with both simulated and real datasets that it may be as flexible as other spatio-temporal smoothing models proposed in the literature and may model spatio-temporal data with several sources of variability.  相似文献   

Computer Simulation of Packing of Particles with Size Distributions Produced by Fragmentation Processes     

Miguel Angel Martín  Francisco J. Muñoz  Miguel Reyes  F. Javier Taguas 《Pure and Applied Geophysics》2015,172(1):141-148

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Effects of site geology on seismic ground motion: early history          下载免费PDF全文

Francisco J. Sánchez‐Sesma  C. B. Crouse 《地震工程与结构动力学》2015,44(7):1099-1113

This is the 6^th contribution in the series of Historical Notes on seminal concepts in earthquake engineering and structural dynamics. It documents the origins and early developments (from the 1880s through 1992) of the effects of site geology on seismic ground motion. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Hybrid simulation of a multi‐span RC viaduct with plain bars and sliding bearings          下载免费PDF全文

Giuseppe Abbiati  Oreste S. Bursi  Philippe Caperan  Luigi Di Sarno  Francisco Javier Molina  Fabrizio Paolacci  Pierre Pegon 《地震工程与结构动力学》2015,44(13):2221-2240

This paper deals with the seismic response assessment of an old reinforced concrete viaduct and the effectiveness of friction‐based retrofitting systems. Emphasis was laid on an old bridge, not properly designed to resist seismic action, consisting of 12 portal piers that support a 13‐span bay deck for each independent roadway. On the basis of an OpenSEES finite element frame pier model, calibrated in a previous experimental campaign with cyclic displacement on three 1:4 scale frame piers, a more complex experimental activity using hybrid simulation has been devised. The aim of the simulation was twofold: (i) to increase knowledge of non‐linear behavior of reinforced concrete frame piers with plain steel rebars and detailing dating from the late 1950s; and (ii) to study the effectiveness of sliding bearings for seismic response mitigation. Hence, to explore the performance of the as built bridge layout and also of the viaduct retrofitted with friction‐based devices, at both serviceability and ultimate limit state conditions, hybrid simulation tests were carried out. In particular, two frame piers were experimentally controlled with eight‐actuator channels in the as built case while two frame piers and eight sliding bearings were controlled with 18‐actuator channels in the isolated case. The remaining frame piers were part of numerical substructures and were updated offline to accurately track damage evolution. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Spatial average aquifer recharge through atmospheric chloride mass balance and its uncertainty in continental Spain   总被引：1，自引：0，他引：1       下载免费PDF全文

Francisco J. Alcalá  Emilio Custodio 《水文研究》2014,28(2):218-236

The atmospheric chloride mass balance (CMB) method allows spatial evaluations of the average diffuse aquifer recharge by rainfall () in large and varied territories when long‐term steady conditions can be assumed. Often, the distributed average CMB variables necessary to calculate have to be estimated from the available variable‐length data series, which may be of suboptimal quality and spatial coverage. This paper explains the use of these data and the reliability of the results in continental Spain, chosen as a large and varied territory. The CMB variables have been regionalized by ordinary kriging at the same 4976 nodes of a 10 km × 10 km grid. Nodal values vary from 14 to 810 mm year^–1, 90% ranging from 30 to 300 mm year^–1. The recharge‐to‐precipitation ratios vary from 0.03 in low‐permeability formations and semiarid areas to 0.65 in some carbonate massifs. Integrated average results for the whole of continental Spain yield a potential aquifer recharge of 64 km³ year^?1, the net recharge over permeable formations (40% of the territory) being 32 km³ year^?1. Two main sources of uncertainty affecting (given by the coefficient of variation, CV), induced by the inherent natural variability of the variables (CV_R) and from mapping (), have been segregated. The average CV_R is 0.13 and could be improved with longer data series. The average is 0.07 and may be decreased with better data coverage. The estimates were compared with other regional and local recharge estimates, being 4% and 1% higher, respectively. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Seasonal dynamics of physical and biological processes in the central California Current System: A modeling study   总被引：1，自引：0，他引：1  

Lin Guo  Fei Chai  Peng Xiu  Huijie Xue  Shivanesh Rao  Yuguang Liu  Francisco P. Chavez 《Ocean Dynamics》2014,64(8):1137-1152

A 3-D physical and biological model is used to study the seasonal dynamics of physical and biological processes in the central California Current System. Comparisons of model results with remote sensing and in situ observations along CalCOFI Line 67 indicate our model can capture the spatial variations of key variables (temperature, nutrients, chlorophyll, and so on) on annual mean and seasonal cycle. In the coastal upwelling system, it is the alongshore wind stress that upwells high nutrients to surface from 60 m and stimulates enhanced plankton biomass and productivity in the upwelling season. As a result, coastal species peak in the late upwelling period (May–July), and oceanic species reach the annual maxima in the oceanic period (August–October). The annual maximum occurs in the late upwelling period for new production and in the oceanic period for regenerated production. From the late upwelling period to the oceanic period, stratification is intensified while coastal upwelling becomes weaker. Correspondingly, the coastal ecosystem retreats from ～300 to ～100 km offshore with significant decline in chlorophyll and primary production, and the oceanic ecosystem moves onshore. During this transition, the decline in phytoplankton biomass is due to the grazing pressure by mesozooplankton in the 0–150 km domain, but is regulated by low growth rates in the 150–500 km offshore domain. Meanwhile, the growth rates of phytoplankton increase in the coastal waters due to deeper light penetration, while the decrease in offshore growth rates is caused by lower nitrate concentrations.  相似文献   

Bio‐Struvite: A New Route to Recover Phosphorus from Wastewater          下载免费PDF全文

Ana Soares  Mamatha Veesam  Francisco Simoes  Elizabeth Wood  Simon A. Parsons  Tom Stephenson 《洁净——土壤、空气、水》2014,42(7):994-997

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Influence of subaqueous processes on the construction and accumulation of an aeolian sand sheet          下载免费PDF全文

Giorgio Basilici  Patrick Francisco Führ Dal' Bó 《地球表面变化过程与地形》2014,39(8):1014-1029

In aeolian sand sheets the interaction between aeolian and subaqueous processes is considered one of the principal factors that controls this depositional environment. To examine the role played by the subaqueous processes on the construction and accumulation of sand sheets, surface deposits and subsurface sedimentary sections of a currently active aeolian sand sheet, located in the Upper Tulum Valley (Argentina), have been examined. On the sand sheet surface, airflows enable the construction of nabkhas, wind‐rippled mantles (flattened accumulations of sand forming wind ripples), megaripples, and small transverse dunes. Subaqueous deposits consist of sandy current ripples covered by muddy laminae. The latter are generated by annual widespread but low‐energy floods that emanate from the nearby mountains in the aftermath of episodes of heavy precipitations. Deposits of subaqueous origin constitute 5% of the accumulated sand sheet thickness. The construction of the sand sheet is controlled by meteorological seasonal changes: the source area, the San Juan river alluvial fan, receives sediment by thaw‐waters in spring–summer; in fall–winter, when the water table lowers in the alluvial fan, the sediment is available for aeolian transport and construction of the sand sheet area. The flood events play an important role in enabling sand sheet accumulation: the muddy laminae serve to protect the underlying deposits from aeolian winnowing. Incipient cement of gypsum on the sand and vegetation cover acts as an additional stabilizing agent that promotes accumulation. Episodic and alternating events of erosion and sedimentation are considered the main reason for the absence of soils and palaeosols. Results from this study have enabled the development of a generic model with which to account for: (i) the influence of contemporaneous subaqueous processes on the construction and accumulation in recent and ancient sand sheets; and (ii) the absence of developed soils in this unstable topographic surface. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献