The effects of deformation inertia (kinetic energy) in the orbital and spin evolution of close-in bodies     

A. C. M. Correia  C. Ragazzo  L. S. Ruiz 《Celestial Mechanics and Dynamical Astronomy》2018,130(8):51

The purpose of this work is to evaluate the effect of deformation inertia on tide dynamics, particularly within the context of the tide response equations proposed independently by Boué et al. (Celest Mech Dyn Astron 126:31–60, 2016) and Ragazzo and Ruiz (Celest Mech Dyn Astron 128(1):19–59, 2017). The singular limit as the inertia tends to zero is analyzed, and equations for the small inertia regime are proposed. The analysis of Love numbers shows that, independently of the rheology, deformation inertia can be neglected if the tide-forcing frequency is much smaller than the frequency of small oscillations of an ideal body made of a perfect (inviscid) fluid with the same inertial and gravitational properties of the original body. Finally, numerical integration of the full set of equations, which couples tide, spin and orbit, is used to evaluate the effect of inertia on the overall motion. The results are consistent with those obtained from the Love number analysis. The conclusion is that, from the point of view of orbital evolution of celestial bodies, deformation inertia can be safely neglected. (Exceptions may occur when a higher-order harmonic of the tide forcing has a high amplitude.)  相似文献   

Numerical analysis of an embankment built on soft soil reinforced with deep mixing columns: Parametric study     

Paulo J. Venda Oliveira  João L.P. Pinheiro  António A.S. Correia 《Computers and Geotechnics》2011

The behaviour of an embankment built on normally consolidated soft soil reinforced with deep mixing columns is studied using a coupled soil–water formulation. The numerical predictions are analysed in terms of settlements, increments in vertical effective stresses and excess pore pressures. Firstly, the effectiveness of the use of deep mixing columns is studied. Afterwards, a parametric analysis is performed to study the influence on the soil-columns system of the replacement ratio (columns’ spacing), the deformability of the embankment and columns, and the coefficient of vertical permeability of the columns.  相似文献   

Reconstruction of remote climate change from borehole temperature measurement in the eastern part of Morocco     

A. E. Barkaoui  A. Correia  Y. Zarhloule  A. Rimi  J. Carneiro  M. Boughriba  M. Verdoya 《Climatic change》2013,118(2):431-441

Data from temperature measurements in boreholes are indicators of the temperature variations associated with past climate change. This paper is a contribution to reconstruct the ground surface temperature history (GSTH) from geothermal data in the eastern part of Morocco. From a set of several temperature logs, measured in the study area, only two were found suitable for estimating the ground surface temperature history (GSTH). In order to reconstruct the surface temperature past changes the functional space inversion method (FSI) was used. The inversion reveals a recent warming in the last century with respective amplitude of 0.1 °C and 1 °C for the boreholes 2952 in Oujda and 1624 in Berkane. These results can be confirmed by the air temperature record of the meteorical station in Oujda despite the scarceness of data beyond 1959.  相似文献   

The VLTI – A Status Report     

A. Glindemann  J. Algomedo  R. Amestica  P. Ballester  B. Bauvir  E. Bugueño  S. Correia  F. Delgado  F. Delplancke  F. Derie  Ph. Duhoux  E. di Folco  A. Gennai  B. Gilli  P. Giordano  Ph. Gitton  S. Guisard  N. Housen  A. Huxley  P. Kervella  M. Kiekebusch  B. Koehler  S. Lévêque  A. Longinotti  S. Ménardi  S. Morel  F. Paresce  T. Phan Duc  A. Richichi  M. Schöller  M. Tarenghi  A. Wallander  M. Wittkowski  R. Wilhelm 《Astrophysics and Space Science》2003,286(1-2):35-44

The Very Large Telescope (VLT) Observatory on Cerro Paranal (2635 m) in Northern Chile is approaching completion. After the four 8-m Unit Telescopes (UT) individually saw first light in the last years, two of them were combined for the first time on October 30, 2001 to form a stellar interferometer, the VLT Interferometer. The combination in pairs of all four UTs was completed in September 2002. In this article, we will describe the subsystems of the VLTI and the planning for the following years. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Comparison of centroid computation algorithms in a Shack–Hartmann sensor     

S. Thomas  T. Fusco  A. Tokovinin  M. Nicolle  V. Michau  G. Rousset 《Monthly notices of the Royal Astronomical Society》2006,371(1):323-336

Analytical theory is combined with extensive numerical simulations to compare different flavours of centroiding algorithms: thresholding, weighted centroid, correlation, quad cell (QC). For each method, optimal parameters are defined in function of photon flux, readout noise and turbulence level. We find that at very low flux the noise of QC and weighted centroid leads the best result, but the latter method can provide linear and optimal response if the weight follows spot displacements. Both methods can work with average flux as low as 10 photons per subaperture under a readout noise of three electrons. At high-flux levels, the dominant errors come from non-linearity of response, from spot truncations and distortions and from detector pixel sampling. It is shown that at high flux, centre of gravity approaches and correlation methods are equivalent (and provide better results than QC estimator) as soon as their parameters are optimized. Finally, examples of applications are given to illustrate the results obtained in the paper.  相似文献   

Complete spin and orbital evolution of close-in bodies using a Maxwell viscoelastic rheology     

Gwenaël Boué  Alexandre C. M. Correia  Jacques Laskar 《Celestial Mechanics and Dynamical Astronomy》2016,126(1-3):31-60

In this paper, we present a formalism designed to model tidal interaction with a viscoelastic body made of Maxwell material. Our approach remains regular for any spin rate and orientation, and for any orbital configuration including high eccentricities and close encounters. The method is to integrate simultaneously the rotation and the position of the planet as well as its deformation. We provide the equations of motion both in the body frame and in the inertial frame. With this study, we generalize preexisting models to the spatial case and to arbitrary multipole orders using a formalism taken from quantum theory. We also provide the vectorial expression of the secular tidal torque expanded in Fourier series. Applying this model to close-in exoplanets, we observe that if the relaxation time is longer than the revolution period, the phase space of the system is characterized by the presence of several spin-orbit resonances, even in the circular case. As the system evolves, the planet spin can visit different spin-orbit configurations. The obliquity is decreasing along most of these resonances, but we observe a case where the planet tilt is instead growing. These conclusions derived from the secular torque are successfully tested with numerical integrations of the instantaneous equations of motion on HD 80606 b. Our formalism is also well adapted to close-in super-Earths in multiplanet systems which are known to have non-zero mutual inclinations.  相似文献   

Temporal variation of ophiuroids associated with the macroalga Amphiroa fragilissima on a Southwest Atlantic coral reef     

Maria Lilian F. Lima  Hilda H. Sovierzoski  Monica D. Correia 《Marine Ecology》2013,34(4):420-431

The species of Ophiuroidea that commonly occur on coral reefs can be found on different substrates and associated with other organisms including algae, sponges, and corals. This study evaluated the temporal variability of the ophiuroid fauna associated with the alga Amphiroa fragilissima on the Ponta Verde coral reef on the coast of Maceió in Alagoas, Northeastern Brazil. Replicate samples of algal substrate were collected at low tide during in the dry and rainy seasons, over a 10‐year period, from 1998–2007. Eight species of Ophiuroidea were identified, with a total of 8736 individuals associated with A. fragilissima. The most dominant and frequent species of Ophiuroidea were Amphipholis squamata and Ophiactis savignyi; all other species were rare. Cluster analysis and nMDS detected four groups, with two groups each occurring only in summer or winter periods, as well as other groups occurring in both periods.  相似文献   

Corrigendum to: “Probing the high latitude ionosphere from ground-based observations: The state of current knowledge and capabilities during IPY (2007–2009)”: [J. Atmos. Sol.-Terr. Phys. 70 (2008) 2293–2308]     

Lucilla Alfonsi  Andrew J. Kavanagh  Ermanno Amata  Pierre Cilliers  Emilia Correia  Mervyn Freeman  Kirsti Kauristie  Ruiyuan Liu  Juha-Pekka Luntama  Cathryn N. Mitchell  G.A. Zherebtsov 《Journal of Atmospheric and Solar》2009,71(5):634

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A magneto-telluric deep crustal study in south-central Portugal     

A. Correia  F. W. Jones  G. K. Dawes  V. R. S. Hutton 《Studia Geophysica et Geodaetica》1993,37(4):331-344

Summary A geothermal anomaly reported to exist in southern Portugal and with heat flow density values as high as 160 mW/m² was studied by the magneto-telluric method. The results of the magneto-telluric survey indicate that the study area is divided into several high electrical resistivity, deep-rooted blocks separated by low electrical resistivity zones. These latter zones coincide with the main trends of the faults that cross the region. The high heat flow density values reported for the area are incompatible with the high electrical resistivities observed in the magneto-telluric survey. Furthermore, heat production values calculated for some of the rocks that crop out in the area of the geothermal anomaly cannot explain the high heat flow density valuss. Since no hydrothermal activity is known for the region and recent volcanism is absent, it is suggested that previous heat flow density calculations for the area covered by the magnetotelluric survey are overestimated.Presented at International Meeting on Terrestrial Heat Flow and the Structure of Lithosphere, Bechyn Castle, Czech Republic, September 2 – 7, 1991.  相似文献   

Soil occupation and atmospheric variations over Sobradinho Lake area. Part one: an observational analysis     

M. F. Correia  M. A. F. da Silva Dias  M. R. da Silva Aragão 《Meteorology and Atmospheric Physics》2006,94(1-4):103-113

Summary Sobradinho Lake lies in the S?o Francisco River Basin, in one of the most arid regions in Northeastern Brazil, within a land stretch categorized as the Lower-middle S?o Francisco, situated at about 40 km away from the municipality of Petrolina (09°23′S–40°30′W) in the state of Pernambuco. The dam, in its full capacity, consists of a lake of approximately 4,214 km²; 280 km in length, the width of which varies from 5 to 50 km. The dam storage capacity is that of 34.1 billion m³ of water. Being situated in a semi-arid region, the dam brought about significant development to local irrigated agriculture. The caatinga ecosystem has, for that matter, undergone considerable changes. Statistical analysis techniques applied to data collected before and after the filling of the lake, made it possible both to make an assessment of the impact of the dam construction on the region meteorology and to diagnose the variability of such an impact on environmental conditions. Results showed that the dam has brought about considerable changes to regional meteorology. The alterations were observed to be more significant as regards atmospheric humidity and wind speed.  相似文献