Exact analytic solutions for the rotation of an axially symmetric rigid body subjected to a constant torque     

Marcello Romano 《Celestial Mechanics and Dynamical Astronomy》2008,101(4):375-390

New exact analytic solutions are introduced for the rotational motion of a rigid body having two equal principal moments of inertia and subjected to an external torque which is constant in magnitude. In particular, the solutions are obtained for the following cases: (1) Torque parallel to the symmetry axis and arbitrary initial angular velocity; (2) Torque perpendicular to the symmetry axis and such that the torque is rotating at a constant rate about the symmetry axis, and arbitrary initial angular velocity; (3) Torque and initial angular velocity perpendicular to the symmetry axis, with the torque being fixed with the body. In addition to the solutions for these three forced cases, an original solution is introduced for the case of torque-free motion, which is simpler than the classical solution as regards its derivation and uses the rotation matrix in order to describe the body orientation. This paper builds upon the recently discovered exact solution for the motion of a rigid body with a spherical ellipsoid of inertia. In particular, by following Hestenes’ theory, the rotational motion of an axially symmetric rigid body is seen at any instant in time as the combination of the motion of a “virtual” spherical body with respect to the inertial frame and the motion of the axially symmetric body with respect to this “virtual” body. The kinematic solutions are presented in terms of the rotation matrix. The newly found exact analytic solutions are valid for any motion time length and rotation amplitude. The present paper adds further elements to the small set of special cases for which an exact solution of the rotational motion of a rigid body exists.  相似文献   

Satellite kinematics – I. A new method to constrain the halo mass–luminosity relation of central galaxies     

Surhud More †  Frank C. van den Bosch  Marcello Cacciato 《Monthly notices of the Royal Astronomical Society》2009,392(2):917-924

Satellite kinematics can be used to probe the masses of dark matter haloes of central galaxies. In order to measure the kinematics with sufficient signal-to-noise ratio, one uses the satellite galaxies of a large number of central galaxies stacked according to similar properties (e.g. luminosity). However, in general, the relation between the luminosity of a central galaxy and the mass of its host halo will have non-zero scatter. Consequently, this stacking results in combining the kinematics of satellite galaxies in haloes of different masses, which complicates the interpretation of the data. In this paper, we present an analytical framework to model satellite kinematics, properly accounting for this scatter and for various selection effects. We show that in the presence of scatter in the halo mass–luminosity relation, the commonly used velocity dispersion of satellite galaxies can not be used to infer a unique halo mass–luminosity relation. In particular, we demonstrate that there is a degeneracy between the mean and the scatter of the halo mass–luminosity relation. We present a new technique that can break this degeneracy, and which involves measuring the velocity dispersions using two different weighting schemes: host weighting (each central galaxy gets the same weight) and satellite weighting (each central galaxy gets a weight proportional to its number of satellites). The ratio between the velocity dispersions obtained using these two weighting schemes is sensitive to the scatter in the halo mass–luminosity relation, and can thus be used to infer a unique relation between light and mass from the kinematics of satellite galaxies.  相似文献   

Modelling galaxy–galaxy weak lensing with Sloan Digital Sky Survey groups     

Ran Li  H. J. Mo  Zuhui Fan  Marcello Cacciato  Frank C. van den Bosch  Xiaohu Yang  Surhud More 《Monthly notices of the Royal Astronomical Society》2009,394(2):1016-1030

We use galaxy groups selected from the Sloan Digital Sky Survey (SDSS) together with mass models for individual groups to study the galaxy–galaxy lensing signals expected from galaxies of different luminosities and morphological types. We compare our model predictions with the observational results obtained from the SDSS by Mandelbaum et al. for the same samples of galaxies. The observational results are well reproduced in a Λ cold dark matter (ΛCDM) model based on the Wilkinson Microwave Anisotropy Probe ( WMAP ) 3-yr data, but a ΛCDM model with higher σ₈, such as the one based on the WMAP 1-yr data, significantly overpredicts the galaxy–galaxy lensing signal. We model, separately, the contributions to the galaxy–galaxy lensing signals from different galaxies: central versus satellite, early type versus late type and galaxies in haloes of different masses. We also examine how the predicted galaxy–galaxy lensing signal depends on the shape, density profile and the location of the central galaxy with respect to its host halo.  相似文献   

Management of non-structural measures in the prevention of flash floods: a case study in the city of Duque de Caxias,state of Rio de Janeiro,Brazil     

Priscila da Cunha Luz Barcellos  Marcello Silva da Costa  Marcio Cataldi  Carlos Alberto Pereira Soares 《Natural Hazards》2017,89(1):313-330

In the last years, natural hazards related to flash floods have caused serious damage and losses to the population of the state of Rio de Janeiro. This research discusses the importance of implementing a methodology for the prevention of flash floods, by comparing the methods applied since 2013 in the city of Duque de Caxias, in the Baixada Fluminense region of the state of Rio de Janeiro, Brazil, and the major prevention actions suggested by the Flash Flood Early Warning System Reference Guide from the National Oceanic and Atmospheric Administration, questioning civil defense professionals about the importance of each method to vulnerable communities. Even without the occurrence of an extreme event that proves the effectiveness of the method between 2014 and 2016, the population will certainly be better prepared to face the risks of disasters in the city in the future. In addition, the study also underscores an approach of approximation between academic studies and operational activities, which is still very incipient in Brazil.  相似文献   

First disk-resolved spectroscopy of (4) Vesta     

Benoît Carry  Pierre Vernazza  Marcello Fulchignoni 《Icarus》2010,205(2):473-482

Vesta, the second largest Main-Belt Asteroid, will be the first to be explored in 2011 by NASA’s Dawn mission. It is a dry, likely differentiated body with spectrum suggesting that is has been resurfaced by basaltic lava flows, not too different from the lunar maria.Here we present the first disk-resolved spectroscopic observations of an asteroid from the ground. We observed (4) Vesta with the ESO-VLT adaptive optics equipped integral-field near-infrared spectrograph SINFONI, as part of its science verification campaign. The highest spatial resolution of ∼90 km on Vesta’s surface was obtained during excellent seeing conditions (0.5^″) in October 2004.We observe spectral variations across Vesta’ surface that can be interpreted as variations of either the pyroxene composition, or the effect of surface aging. We compare Vesta’s 2 μm absorption band to that of howardite-eucrite-diogenite (HED) meteorites that are thought to originate from Vesta, and establish particular links between specific regions and HED subclasses. The overall composition is found to be mostly compatible with howardite meteorites, although a small area around 180°E longitude could be attributed to a diogenite-rich spot. We finally focus our spectral analysis on the characteristics of Vesta’s bright and dark regions as seen from Hubble Space Telescope’s visible and Keck-II’s near-infrared images.  相似文献   

Baseline geochemical mapping of Sardinia (Italy)     

B. De Vivo  M. Boni  A. Marcello  M. Di Bonito  A. Russo 《Journal of Geochemical Exploration》1997,60(1):77-90

A total of about 20,000 stream sediment samples from about 13,000 km² were collected in Sardinia and analysed for eleven elements (Ag, Co, Cr, Cu, F, Hg, Mn, Mo, Ni, Pb, Sb and Zn) by Ente Minerario Sardo (EMS), aimed at mineral exploration. We have reutilized 16,890 samples (covering an area of 7987 km²) of the above data to compile geochemical baseline maps for all single elements as well as maps showing the regional variability of factor scores resulting from R-mode factor analysis. This type of maps has a particular relevance to environmental issues, especially in a region such as Sardinia which has been mined since pre-Roman times.  相似文献   

The dependence of asteroid lightcurves on the orientation parameters and the shapes of asteroids     

M. Antonietta Barucci  Marcello Fulchignoni 《Earth, Moon, and Planets》1982,27(1):47-57

The dependence of asteroidal light curves has been derived from the obliquity, aspect and phase angles. The effects of an angle variation are discussed taking into account the possible geometry of an asteroidal body.The amplitude-aspect relation is discussed for different asteroidal shapes.On the basis of this relation a graphical attempt to determine the value of the aspect from the light curves' amplitude is described.  相似文献   

Seasonal changes of the profundal macrobenthic community in a polluted lake     

Marcello Bazzanti  Marco Seminara 《Aquatic Sciences - Research Across Boundaries》1985,47(1):57-63

Late summer and winter structures of the profundal macrobenthos in a polluted lake (Lake Nemi, Central Italy) were compared to verify the relative differences in the faunal structure and the magnitude of the winter recovery of this community. Densities of Oligochaetes and Chironomids did not vary significantly from summer to winter, the latter not showing any recolonization of the profundal zone. Structure and diversity of the total fauna, and Oligochaete/Chironomid ratio were very similar in the two periods. Our results suggest that in a severely polluted lake, with a strong and lasting oxygen deficit in the hypolimnic zone, a lack of recovery of profundal macrobenthos may be expected in improved environmental winter conditions.  相似文献   

Deformation between 1989 and 1997 at Piton de la Fournaise volcano retrieved from correlation of panchromatic airborne images     

Marcello de Michele  Pierre Briole 《Geophysical Journal International》2007,169(1):357-364

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Observing water-level variations from space-borne high-resolution Synthetic Aperture Radar (SAR) image correlation     

Daniel Raucoules  Gonéri Le Cozannet  Marcello de Michele  Sylvain Capo 《国际地球制图》2018,33(9):977-987

The potential of correlating high-resolution Synthetic Aperture Radar images to estimate local water-level variations is analysed based on observing the motions of floating structures. By computing range and azimuth offsets on a COSMO-SkyMed multi-temporal data-set in an area of the French Atlantic Coast, displacement signatures were detected in several harbours of the region. They can be associated with specific floating structures, whose vertical motion is mostly driven by tides. Although the image resolution is not the best achievable for the COSMO-SkyMed sensor, comparison with ground-based tide information revealed that the obtained space-borne measurements are consistent with the tide gauges to a decimetric accuracy. Even if the requirements for traditional users of tidal data are not met by the current revisit time of the COSMO-SkyMed constellation, the method proposed here provides complementary measures, which are already well aligned to requirements of users concerned with long-term sea-level variation and river or lake water stocks.  相似文献