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151.
A. Collier Cameron D. M. Wilson R. G. West L. Hebb X.-B. Wang S. Aigrain F. Bouchy D. J. Christian W. I. Clarkson B. Enoch M. Esposito E. Guenther C. A. Haswell G. Hébrard C. Hellier K. Horne J. Irwin S. R. Kane B. Loeillet T. A. Lister P. Maxted M. Mayor C. Moutou N. Parley D. Pollacco F. Pont D. Queloz R. Ryans I. Skillen R. A. Street S. Udry P. J. Wheatley 《Monthly notices of the Royal Astronomical Society》2007,380(3):1230-1244
152.
We studied the stability of the restricted circular three-body problem. We introduced a model Hamiltonian in action-angle Delaunay variables. which is nearly-integrable with the perturbing parameter representing the mass ratio of the primaries. We performed a normal form reduction to remove the perturbation in the initial Hamiltonian to higher orders in the perturbing parameter. Next we applied a result on the Nekhoroshev theorem proved by Pöschel [13] to obtain the confinement in phase space of the action variables (related to the elliptic elements of the minor body) for an exponentially long time. As a concrete application. we selected the Sun-Ceres-Jupiter case, obtaining (after the proper normal form reduction) a stability result for a time comparable to the age of the solar system (i.e., 4.9 · 109 years) and for a mass ratio of the primaries less or equal than 10–6. 相似文献
153.
Giannini Leonardo Maria Varone Chiara Esposito Carlo Marmoni Gian Marco Scarascia Mugnozza Gabriele Schilir Luca 《Landslides》2022,19(8):2005-2019
Landslides - Earthquake-induced landslides represent a significant seismic hazard since they can largely increase the damage and losses due to a seismic event, an issue that must be considered in... 相似文献
154.
Hron Karel Menafoglio Alessandra Palarea-Albaladejo Javier Filzmoser Peter Talská Renáta Egozcue Juan José 《Mathematical Geosciences》2022,54(1):71-93
Mathematical Geosciences - It often occurs in practice that it is sensible to give different weights to the variables involved in a multivariate data analysis—and the same holds for... 相似文献
155.
Arianna?Secchiari Alessandra?MontaniniEmail author Delphine?Bosch Patrizia?Macera Dominique?Cluzel 《Contributions to Mineralogy and Petrology》2018,173(8):66
The New Caledonia ophiolite hosts one of the rare examples of crust-mantle sections built in a nascent arc environment, providing the unique opportunity to investigate the first stages of arc magmatism in a subduction setting. The sequence consists of refractory harzburgites, overlain by ultramafic (dunites and wehrlites) and mafic lithologies (gabbronorites). The gabbronorites occur in the upper part of the sequence as decimetre to metre-size sills. They are mainly formed (??55 to 70 vol%) of Ca-rich plagioclase (An up to 96 mol%) and high Mg# (88–92), Al2O3-poor (1.5–2.4 wt%) clinopyroxene (8–20 vol%), often rimmed by interstitial or poikilitic orthopyroxene (6–27 vol%). Mg-rich olivine (3–15 vol%, Fo?=?87–89 mol%) occurs as anhedral, resorbed crystals. Whole rock (WR) compositions exhibit high Mg# (86–92) and strikingly low trace element contents. They own LREE-depleted patterns, with nearly flat (0.82?≤?DyN/YbN?≤?1.00) and low HREE (YbN?=?0.2–0.9) and positive Eu anomalies. Clinopyroxene trace element chemistry mirrors the extreme depletion of the WR. By contrast, FME enrichments are observed for WR and clinopyroxene. Geochemical models show that the gabbronorites crystallized from primitive, ultra-depleted melts bearing evidence of fluid contamination processes, but with significantly different geochemical signatures compared to boninitic rocks worldwide, i.e. lower LREE-MREE, and absence of Nb depletion and Zr–Hf enrichments. Nd isotopes (+?8.2?≤?εNdi?≤?+?13.1), together with radiogenic Pb isotopic ratios, support an origin from a DMM source variably modified by slab fluids. We propose that the geochemical signature of the New Caledonia gabbronorites reflect emplacement of primitive, non-aggregated, magma batches in the lower fore-arc crust, during the first phases of arc formation. 相似文献
156.
Alessandra Celletti Gabriella Pinzari 《Celestial Mechanics and Dynamical Astronomy》2006,95(1-4):327-344
In the framework of the orbital determination methods, we study some properties related to the algorithms developed by Gauss, Laplace and Mossotti. In particular, we investigate the dependence of such methods upon the size of the intervals between successive observations, encompassing also the case of two nearby observations performed within the same night. Moreover we study the convergence of Gauss algorithm by computing the maximal eigenvalue of the jacobian matrix associated to the Gauss map. Applications to asteroids and Kuiper belt objects are considered. 相似文献
157.
158.
The problem of stability of the Lagrangian equilibrium point of the circular restricted problem of three bodies is investigated in the light of Nekhoroshev-like theory. Looking for stability over a time interval of the order of the estimated age of the universe, we find a physically relevant stability region. An application of the method to the Sun-Jupiter and the Earth-Moon systems is made. Moreover, we try to compare the size of our stability region with that of the region where the Trojan asteroids are actually found; the result in such case is negative, thus leaving open the problem of the stability of these asteroids. 相似文献
159.
Francesco Mastrototaro Porzia Maiorano Agostina Vertino Daniela Battista Antonella Indennidate Alessandra Savini Angelo Tursi Gianfranco D'Onghia 《Marine Ecology》2013,34(3):313-320
During a research cruise carried out in April 2010, aimed at updating the knowledge on the biodiversity of the Santa Maria di Leuca (SML) cold‐water coral province (Mediterranean Sea), a facies of the sea pen Kophobelemnon stelliferum (Muller, 1776) was found on mud‐dominated bottoms. This finding represents a new species and a new habitat record from the SML coral province as well as a new bathyal facies in the whole Central Mediterranean Sea. The colonies were collected using an epi‐benthic sledge, at depths between 400 and 470 m. A significant positive relationship between polyp number and colony length was detected. Density of the colonies ranged from 0.003 to 0.038 N·m?2. Differences and affinities between Mediterranean and Atlantic occurrences of K. stelliferum are discussed. 相似文献
160.
Alessandra?CellettiEmail author Letizia?Stefanelli Elena?Lega Claude?Froeschlé 《Celestial Mechanics and Dynamical Astronomy》2011,109(3):265-284
We perform an analysis of the dynamics of the circular, restricted, planar three-body problem under the effect of different
kinds of dissipation (linear, Stokes and Poynting–Robertson drags). Since the problem is singular, we implement a regularization
technique in the style of Levi–Civita. The effect of the dissipation is often to decrease the semi-major axis; as a consequence
the minor body collides with one of the primaries. In general, it is quite difficult to find non-collision orbits using random
initial conditions. However, by means of the computation of the Fast Lyapunov Indicators (FLI), we obtain a global view of
the dynamics. Precisely, we detect the regions of the phase space potentially belonging to basins of attraction. This investigation
provides information on the different regions of the phase space, showing both collision and non-collision trajectories. Moreover,
we find periodic orbit attractors for the case of linear and Stokes drags, while in the case of the Poynting–Robertson effect
no other attractors are found beside the primaries, unless a fourth body is added to counterbalance the dissipative effect. 相似文献