The dynamics of the de Sitter resonance     

Alessandra Celletti  Fabrizio Paita  Giuseppe Pucacco 《Celestial Mechanics and Dynamical Astronomy》2018,130(2):15

We study the dynamics of the de Sitter resonance, namely the stable equilibrium configuration of the first three Galilean satellites. We clarify the relation between this family of configurations and the more general Laplace resonant states. In order to describe the dynamics around the de Sitter stable equilibrium, a one-degree-of-freedom Hamiltonian normal form is constructed and exploited to identify initial conditions leading to the two families. The normal form Hamiltonian is used to check the accuracy in the location of the equilibrium positions. Besides, it gives a measure of how sensitive it is with respect to the different perturbations acting on the system. By looking at the phase plane of the normal form, we can identify a Laplace-like configuration, which highlights many substantial aspects of the observed one.  相似文献   

Tidal effects on the LAGEOS–LARES satellites and the LARASE program     

Giuseppe Pucacco  David M. Lucchesi 《Celestial Mechanics and Dynamical Astronomy》2018,130(10):66

The effects of solid and ocean tides have been computed on the right ascension of the ascending node of the two LAGEOS and LARES satellites and on the argument of pericenter of LAGEOS II. Their effects—together with the possible mis-modeling related to systematic errors in the estimate of the tidal coefficients, especially in the case of ocean tides—are quite important to be well established for the key role of the LAGEOS satellites, as well as of the newly LARES, in space geodesy and geophysics as well as in fundamental physics measurements. In the case of the measurement of the Lense–Thirring effect, the mis-modeling of long-period tides may mimic a secular effect on the cited orbital elements, thus producing a degradation in the measurement of the relativistic precession. A suitable combination of the orbital elements of the three satellites can help in avoiding the effects of the long-period tides of degree \(\ell =2\) (as for the Lunar solid tides with periods of 18.6 and 9.3 years) and \(\ell =4\), but other long-period tides, as the ocean \(K_1\) tide, which has the same periodicities of the right ascension of the ascending node \(\varOmega \) of the satellites, may strongly influence the measurement, especially if it is performed over a relatively short time span. These results are particularly important in the case of LARES, since they are new and because of the role that the orbit of LARES, and especially of its ascending node right ascension, will have in a new measurement of the Lense–Thirring effect by the joint analysis of its orbit with that of the two LAGEOS.  相似文献   

Water–gas dynamics and coastal land subsidence over Chioggia Mare field, northern Adriatic Sea     

Pietro Teatini  Domenico Baú  Giuseppe Gambolati 《Hydrogeology Journal》2000,8(5):462-479

A major development programme comprising 15 gas fields of the northern Adriatic Sea has recently been submitted to the Ministry of the Environment, VIA Committee for the assessment of the environmental impact, by ENI-Agip, the Italian national oil company. One of the largest reservoirs is Chioggia Mare, located about 10 km offshore of the Venetian littoral, with a burial depth of 1000–1400 m. The planned gas production from this field is expected to impact the shoreline stability with a potential threat to the city of Venice, 25 km northwest of the center of Chioggia Mare. To evaluate the risk of anthropogenic land subsidence due to gas withdrawal, a numerical model was developed that predicts the compaction of both the gas-bearing formations and the lateral/bottom aquifer (water drive) during a 13-year producing and a 12-year post-production period, and the transference of the deep compaction to the ground surface. To address the uncertainty of a few important hydromechanical parameters, several scenarios are simulated and the most pessimistic predictions obtained. The modeling results show that at most 1 cm of land subsidence over 25 years may be expected at the city of Chioggia, whereas Venice is not subject to settlement. If aquifer drawdown is mediated by water injection, land subsidence is arrested 5 km offshore, with the Chioggia littoral zone experiencing a rebound of 0.6–0.7 cm. Electronic Publication  相似文献   

Correlation between eruptions of Mount Etna, Sicily, and regional earthquakes as seen in historical records from AD 1582     

Alastaif D. L. Sharp  Giuseppe Lombardo  Paul M. Davis 《Geophysical Journal International》1981,65(2):507-523

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Populating a cluster of galaxies – I. Results at         

Volker Springel  Simon D. M. White  Giuseppe Tormen  Guinevere Kauffmann 《Monthly notices of the Royal Astronomical Society》2001,328(3):726-750

We simulate the assembly of a massive rich cluster and the formation of its constituent galaxies in a flat, low-density universe. Our most accurate model follows the collapse, the star formation history and the orbital motion of all galaxies more luminous than the Fornax dwarf spheroidal, while dark halo structure is tracked consistently throughout the cluster for all galaxies more luminous than the SMC. Within its virial radius this model contains about     dark matter particles and almost 5000 distinct dynamically resolved galaxies. Simulations of this same cluster at a variety of resolutions allow us to check explicitly for numerical convergence both of the dark matter structures produced by our new parallel N -body and substructure identification codes, and of the galaxy populations produced by the phenomenological models we use to follow cooling, star formation, feedback and stellar aging. This baryonic modelling is tuned so that our simulations reproduce the observed properties of isolated spirals outside clusters. Without further parameter adjustment our simulations then produce a luminosity function, a mass-to-light ratio, luminosity, number and velocity dispersion profiles, and a morphology–radius relation which are similar to those observed in real clusters. In particular, since our simulations follow galaxy merging explicitly, we can demonstrate that it accounts quantitatively for the observed cluster population of bulges and elliptical galaxies.  相似文献   

On Potential Spectroscopic Detection of Microfossils on Mars     

Giuseppe A. Marzo  Romolo Politi  Armando Blanco  Rosario Brunetto  Sergio Fonti  Vincenzo Orofino 《Earth, Moon, and Planets》2007,101(3-4):127-140

There is much evidence about the ancient presence of water on Mars and it is reasonable to suppose that simple forms of life may have developed during the geological evolution of the planet. In such a case traces of this extinct life could still be present on the planet in form of microfossils included into some geological layer. The rover payloads planned for the next decades will include spectrometers in order to accomplish various scientific tasks. In this respect, we have developed a quantitative model for microfossil inclusions into a crystalline matrix. Such a method foresees some visible effects on measurements obtained via spectroscopic techniques such as infrared reflectance and Raman spectroscopy. In this work we present the quantitative model of the fossilization process and the effects that the microfossil inclusions should have in the real spectra, evaluated by means of computer simulations. Preliminary measurements, in order to provide examples of future model testing, have been performed on samples of homogeneous composition, but with detectable microfossils content, collected at the K–T sequence placed near Gubbio (Italy). The preliminary results are presented and discussed in order to investigate the potential application of such spectroscopic techniques for the detection of extinct life.  相似文献   

Precision measurement of the Sun's gravitational field by means of the twin probe method     

Bruno Bertotti  Giuseppe Colombo 《Astrophysics and Space Science》1972,17(1):223-237

An accurate measurement of the gravitational field of the Sun, needed for the verification of the theories of gravitation, requires the use of a geodesic test body. To eliminate the effect of non-gravitational forces (mainly the solar radiation pressure) we propose to use two twin space probes, whose surface has identical geometrical and optical properties, but with different mass. Their differential motion leads to the determination of the motion of an ideal geodesic point. We discuss in detail the various conditions which are needed to ensure the required degree of identity and submit as a possible solution two cylindrical probes, whose sides are covered by cavities to make them absorbing, rotating at a fast rate around an axis orthogonal to the ecliptic plane. We discuss briefly also the accuracy in the determination of the parameters of the metric field of the Sun obtainable from range measurements.Work done at the European Space Research Institute, Frascati, Italy  相似文献   

The 1538 Monte Nuovo eruption (Campi Flegrei,Italy)     

Mauro Di Vito  Lucio Lirer  Giuseppe Mastrolorenzo  Giuseppe Rolandi 《Bulletin of Volcanology》1987,49(4):608-615

On 29 September 1538 a week-long eruption began in Campi Flegrei forming a new volcano, Monte Nuovo. From contemporary accounts of the eruption, it has been possible to reconstruct the main phases of activity. These phases may be correlated with different depositional units identified in the field. The eruption opened with a hydromagmatic phase, during which a large amount of external water (meteoric or sea water) was able to interact with the magma. The exhaustion of the water supply and decrease in volatile content initiated a change in the dynamic conditions of eruption, which became more purely magmatic in character and less explosive.  相似文献   

Some considerations on the measurements and calculations relating to the European calibration line     

Luigi Solaini  Giuseppe Inghilleri 《Journal of Geodesy》1963,37(3):235-238

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La conducibilità termica di alcune rocce italiane     

Mario Bossolasco  Giuseppe Cicconi  Claudio Eva 《Pure and Applied Geophysics》1963,54(1):64-76

Riassunto Il lavoro riguarda una serie di misure su campioni di 5 tipi diversi di rocce italiane aventi lo scopo di determinare la rispettiva conducibilità termica. Dopo la descrizione dell'apparecchiatura usata, vengono esposti i risultati ottenuti, analizzando in dettaglio l'influenza della scistosità. In base alle misure fatte su campioni di ardesia questa influenza può esprimersi con la formola:k =k ₉₀+m cos , dove è l'angolo fra la direzione del flusso termico ed il piano di stratificazione, mentrem è una costante caratteristica della scistosità.

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Summary Experiments made for obtain the thermal conductivity of different kinds of italian rocks are described and discussed. The effect of schistosity was derived for slate rocks and it can be represented with the formula:k =k ₉₀+m cos , where is the angle between the direction of thermal flux and the plain of stratification, whereasm is a constant characterizing the schistosity.

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Lavoro eseguito con un contributo del Consiglio Nazionale delle Ricerche (Comitato per la Geologia).  相似文献