Ejection and collision orbits of the spatial restricted three-body problem     

Jaume Llibre  J. Martínez Alfaro 《Celestial Mechanics and Dynamical Astronomy》1985,35(2):113-128

We begin by describing the global flow of the spatial two body rotating problem, =0. The remainder of the work is devoted to study the ejection and collision orbits when >-0. We make use of the blow up techniques to show that for any fixed value of the Jacobian constant the set of these orbits is diffeomorphic to S²×R. Also we find some particular collision-ejection orbits.  相似文献   

The recreational use of beaches and consequences for the development of new trends in management: the case of the beaches of the Metropolitan Region of Barcelona (Catalonia, Spain)     

Françoise Breton  Jaume Clapés  Alfons Marquès  Gerda K. Priestley 《Ocean & Coastal Management》1996,32(3):153-180

This article offers some reflections on beach management, on the basis of the results of a survey on the recreational use of beaches and beach users' perception, which was carried out in the Metropolitan Region of Barcelona in 1992. The first part outlines the situation of the beaches, recent metropolitan beach policy and the organization of administrative bodies responsible for beach management. Survey objectives and methods are also explained briefly. In the second part, the principal results of the survey are presented and different beaches are compared in an attempt to analyse the types of users, the uses they make and the perception they have of the beaches. The conclusions identify new emerging social needs which demonstrate that new trends in beach management are also needed. Practical recommendations, related to this emerging perception of beaches as natural systems, are suggested.  相似文献   

On the central configurations of the planar 1 + 3 body problem     

Montserrat Corbera  Josep Maria Cors  Jaume Llibre 《Celestial Mechanics and Dynamical Astronomy》2011,109(1):27-43

We consider the Newtonian four-body problem in the plane with a dominat mass M. We study the planar central configurations of this problem when the remaining masses are infinitesimal. We obtain two different classes of central configurations depending on the mutual distances between the infinitesimal masses. Both classes exhibit symmetric and non-symmetric configurations. And when two infinitesimal masses are equal, with the help of extended precision arithmetics, we provide evidence that the number of central configurations varies from five to seven.  相似文献   

Spatio-temporal analysis of rockfall pre-failure deformation using Terrestrial LiDAR   总被引：2，自引：2，他引：0  

Manuel Jesús Royán  Antonio Abellán  Michel Jaboyedoff  Joan Manuel Vilaplana  Jaume Calvet 《Landslides》2014,11(4):697-709

We present a long-term spatio-temporal analysis of rock slope evolution using a Terrestrial LiDAR aiming to improve our understanding of the link between pre-failure deformation and the spatial prediction of rockfalls. We monitored the pilot study area located at the Puigcercós cliff (Catalonia, Spain) over a period of 1,705 days and detected the deformation of nine different cliff regions together with a high rockfall activity. An exact match was observed between the progressively deformed areas and the regions recently affected by three of the highest magnitude rockfall events, demonstrating a causal relationship between pre-failure deformation and rockfall occurrence. These findings allowed us to make a forward spatial prediction of future failures, hypothesizing a high probability of failure in the six remaining regions. We observed an exponential acceleration of the deformation close to failure, in accordance with tertiary creep theory. However, the temporal analysis of the deformed areas showed a complex and variable behavior, so no exact prediction of the date of failure can yet be made. Our findings have broadened our understanding of the pre-failure behavior of rockfalls and have clear implications for the future implementation of early warning systems.  相似文献   

Selenium and iodine anomalies in soils and health     

Jaume Bech  Elena Korobova  Carmen Pérez-Sirvent 《Journal of Geochemical Exploration》2010

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On the existence of central configurations of <Emphasis Type="Italic">p</Emphasis> nested regular polyhedra     

Montserrat Corbera  Jaume Llibre 《Celestial Mechanics and Dynamical Astronomy》2010,106(2):197-207

In this paper we prove, for all p ≥ 2, the existence of central configurations of the pn-body problem where the masses are located at the vertices of p nested regular polyhedra having the same number of vertices n and a common center. In such configurations all the masses on the same polyhedron are equal, but masses on different polyhedra could be different.  相似文献   

New constraints on the Messinian sealevel drawdown from 3D seismic data of the Ebro Margin,western Mediterranean     

Roger Urgeles  Angelo Camerlenghi  Daniel Garcia‐Castellanos  Ben De Mol  Miquel Garcés  Jaume Vergés  Ian Haslam  Martin Hardman 《Basin Research》2011,23(2):123-145

We present new 3D seismic and well data from the Ebro Margin, NW Mediterranean Sea, to shed new light on the processes that formed the Messinian Erosion Surfaces (MES) of the Valencia Trough (Mediterranean Sea). We combine these data with backstripping techniques to provide a minimum estimate of the Messinian sea level fall in the EBRO Margin, as well as coupled isostasy and river incision and transport modeling to offer new constraints on the evolution of the adjacent subaerial Ebro Basin. Four major seismic units are identified on the Cenozoic Ebro Margin, based on the seismic data, including two major prograding megasequences that are separated by a major unconfirmity: the MES. The 3D seismic data provide an unprecedented view of the MES and display characteristic features of subaerial incision, including a drainage network with tributaries of at least five different orders, terraces and meandering rivers. The Messinian landscape presents a characteristic stepped‐like profile that allows the margin to be subdivided in three different regions roughly parallel to the coastline. No major tectonic control exists on the boundaries between these regions. The boundary between the two most distal regions marks the location of a relatively stable base level, and this is used in backstripping analysis to estimate the magnitude of sea level drop associated with the Messinian Salinity Crisis on the Ebro Margin. The MES on the Ebro Margin is dominated by a major fluvial system, that we identify here as the Messinian Ebro River. The 3D seismic data, onshore geology and modeling results indicate that the Ebro River drained the Ebro Basin well in advance of the Messinian.  相似文献   

    

Jaume Llibre  Daniel Pa&#;ca 《Celestial Mechanics and Dynamical Astronomy》2007,98(3):217

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Periodic orbits for a class of galactic potentials     

Felipe Alfaro  Jaume Llibre  Ernesto Pérez-Chavela 《Astrophysics and Space Science》2013,344(1):39-44

In this work, applying general results from averaging theory, we find periodic orbits for a class of Hamiltonian systems H whose potential models the motion of elliptic galaxies.  相似文献   

Impacts of climate change on water resources in the Mediterranean Basin: a case study in Catalonia,Spain   总被引：1，自引：0，他引：1  

Diana Pascual  Eduard Pla  Joan A. Lopez-Bustins  Javier Retana  Jaume Terradas 《水文科学杂志》2013,58(12):2132-2147

Abstract

Most climate change projections show important decreases in water availability in the Mediterranean region by the end of this century. We assess those main climate change impacts on water resources in three medium-sized catchments with varying climatic conditions in northeastern Spain. A combination of hydrological modelling and climate projections with B1 and A2 IPCC emission scenarios is performed to infer future streamflows. The largest reduction (34%) in mean streamflows (for 2076–2100) is expected in the headwaters of the two wettest catchments, while lower decreases (25% of mean value for 2076–2100) are expected in the drier one. In all three catchments, autumn and summer are the seasons with the most notable projected decreases in streamflow, of 50% and 30%, respectively. Thus, ecological flows in the study area might be noticeably influenced by climate change, especially in the headwaters of the wet catchments.  相似文献