Continuation of normal doubly symmetric orbits in conservative reversible systems

In this paper we introduce the concept of a quasi-submersive mapping between two finite-dimensional spaces, we obtain the main properties of such mappings, and we introduce “normality conditions” under which a particular class of so-called “constrained mappings” are quasi-submersive at their zeros. Our main application is concerned with the continuation properties of normal doubly symmetric orbits in time-reversible systems with one or more first integrals. As examples we study the continuation of the figure-eight and the supereight choreographies in the N-body problem.     

Potential implications of global warming and barrier island degradation on future hurricane inundation,property damages,and population impacted

Hurricane flooding is a leading natural threat to coastal communities. Recent evidence of sea level rise coupled with potential future global warming indicate that sea level rise will accelerate and hurricanes may intensify over the coming decades. In regions fronted by barrier islands, the protective capacity of these islands may diminish as they are degraded by rising sea level. Here we present a hydrodynamic and geospatial analysis of the relative role of barrier island degradation on potential future hurricane flooding. For the City of Corpus Christi, Texas, USA, hurricane flooding is projected to rise between 20% and 70% by the 2030s, resulting in an increase in property damages and impacted population. These findings indicate that adaptive management strategies should be developed and adopted for mitigating loss of natural barrier islands when these islands act as protective features for populated bayside communities. Finally, this study illustrates a method for applying models to forecast future storm protection benefits of barrier island restoration projects.     

Asteroid 2002NY40 as a source of meteorite-dropping bolides

The existence of asteroidal meteoroid streams capable of producing meteorite-dropping bolides has long being invoked, but evidence is scarce. Recent modelling of previously reported associations suggests that the time-scales to keep the orbital coherence of these streams producing meteorites are too short. We present an unequivocal association between near earth object (NEO) 2002NY40 and at least one bright fireball detected over Finland in 2006 August. Another two additional fireballs recorded from Spain and Finland seem to be related, together producing a fireball-producing stream (β Aquarids). On the basis of historical data, the 2006 finding suggests the existence of a meteoroid complex capable of producing meteorites. Taking into account present time-scales for orbital decoherence, if 2002NY40 has large meteoroids associated with it, such behaviour would be the consequence of a relatively recent asteroidal fragmentation. Supporting our claim, the heliocentric orbits of two recently discovered NEOs, 2004NL8 and 2002NY40, were found to exhibit a good similarity to each other and also to the orbits of the three bolides. The fireball spectra of the two Finish bolides showed that the chemical abundances of these objects are consistent with the main elements found in chondrites. This result is consistent with the probable Low iron, Low metal (LL) chondritic mineralogy of asteroid 2002NY40. Consequently, this asteroid may be delivering LL chondrites to the Earth. Additional fireball reports found in the literature suggest that the associated β Aquarid complex may have been delivering meteorites to the Earth during, at least, the last millennium.     

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

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.     

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

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.     

Effects of site geology on seismic ground motion: early history

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.     

Hybrid simulation of a multi‐span RC viaduct with plain bars and sliding bearings

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.     

Spatial average aquifer recharge through atmospheric chloride mass balance and its uncertainty in continental Spain

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.