排序方式: 共有26条查询结果,搜索用时 0 毫秒
11.
Ettore Cardarelli Michele Cercato Antonio Cerreto Gerardina Di Filippo 《Geophysical Prospecting》2010,58(4):685-695
Near‐surface cavities can pose serious hazards to human safety, especially in highly urbanized town centres. The location of subsurface voids, the estimation of their size and the evaluation of the overburden thickness are necessary to assess the risk of collapse. In this study, electrical resistivity tomography (ERT) and seismic refraction tomography data are integrated in a joint interpretation process for cavity location in the city of Rome. ERT is a well established and widely employed method for cavity detection. However, additional information provided by seismic refraction tomography is capable of eliminating some potential pitfalls in resistivity data interpretation. We propose that the structure of the cavities defined by ERT can be used as a base to optimize seismic refraction tomography investigations within the framework of a joint interpretation process. Data integration and the insertion of a priori information are key issues for reducing the uncertainties associated with the inversion process and for optimizing both acquisition procedures and computation time. Herein, the two geophysical methods are tested on both synthetic and real data and the integration of the results is found to be successful in detecting isolated cavities and in assessing their geometrical characteristics. The cavity location inferred by geophysical non‐invasive methods has been subsequently confirmed by direct inspection. 相似文献
12.
Cristiana Guerranti Stefania Ancora Nicola Bianchi Guido Perra Emiliano Leonida Fanello Simonetta Corsolini Maria Cristina Fossi Silvano Ettore Focardi 《Marine pollution bulletin》2013
Perfluorinated compounds (PFCs), widely used for their hydro-oil repellent properties, are almost non-degradable in the environment; there is scientific evidence that indicate bioaccumulation. They represent a threat to many organisms, because they are toxic and are endocrine disruptors. Scientific studies have demonstrated the presence of PFCs in blood and liver samples of fish, turtles, birds and mammals of marine ecosystems in different geographical areas. The aim of this study was to determine the distribution of PFOS and PFOA in blood samples of the marine turtle Caretta caretta, using a minimally invasive sampling procedure. 49 blood samples of marine turtle, taken from several Italian marine turtle rescue centers, were analyzed. While PFOA was never detected, measurable concentrations of PFOS were found in 15 blood samples; the values show a range from 1.14 ng/g to 28.51 ng/g (wet wt.). No differences between groups of samples taken from different areas were found. 相似文献
13.
Riccardo Campana Mauro Orlandini Ettore Del Monte Marco Feroci Filippo Frontera 《Experimental Astronomy》2014,37(3):599-613
Low-inclination, low altitude Earth orbits (LEO) are of increasing importance for astrophysical satellites, due to their low background environment. Here, the South Atlantic Anomaly (SAA) is the region with the highest amount of radiation. We study the radiation environment in a LEO (500–600 km altitude, 4° inclination) through the particle background measured by the Particle Monitor (PM) experiment onboard the BeppoSAX satellite, between 1996 and 2002. Using time series of particle count rates measured by PM we construct intensity maps and derive SAA passage times and fluences. The low-latitude SAA regions are found to have an intensity strongly decreasing with altitude and dependent on the magnetic rigidity. The SAA extent, westward drift and strength vs altitude is shown. 相似文献
14.
15.
Cesare Barbieri Carlo Blanco Beatrice Bucciarelli Regina Coluzzi Andrea Di Paola Luciano Lanteri Gian Luca Li Causi Ettore Marilli Piero Massimino Vincenzo Mezzalira Stefano Mottola Roberto Nesci Alessandro Omizzolo Fernando Pedichini Francesca Rampazzi Corinne Rossi Ruggero Stagni Milcho Tsvetkov Roberto Viotti 《Experimental Astronomy》2003,15(1):29-43
There is a widespread interest to digitize the precious information contained in the astronomical plate archives, both for
the preservation of their content and for its fast distribution to all interested researchers in order to achieve their better
scientific exploitation. This paper presents the first results of our large-scale project to digitize the archive of plates
of the Italian Astronomical Observatories and of the Specola Vaticana. Similar systems, composed by commercial flat-bed retro-illuminated
scanners plus dedicated personal computers and acquisition and analysis software, have been installed in all participating
Institutes. Ad-hoc codes have been developed to acquire the data, to test the suitability of the machines to our scientific needs, and to reduce
the digital data in order to extract the astrometric, photometric and spectroscopic content. Two more elements complete the
overall project: the provision of high quality BVRI CCD sequences in selected fields with the Campo Imperatore telescopes,
and the distribution of the digitized information to all interested researchers via the Web. The methods we have derived in
the course of this project have been already applied successfully to plates taken by other Observatories, for instance at
Byurakan and at Hamburg. 相似文献
16.
Ettore Carretti 《Journal of Astrophysics and Astronomy》2011,32(4):457-463
Diffuse polarized emission by synchrotron is a key tool to investigate magnetic fields in the Milky Way, particularly the
ordered component of the large scale structure. Key observables are the synchrotron emission itself and the RM is by Faraday
rotation. In this paper the main properties of the radio polarized diffuse emission and its use to investigate magnetic fields
will be reviewed along with our current understanding of the galactic magnetic field and the data sets available. We will
then focus on the future perspective discussing RM-synthesis – the new powerful instrument devised to unlock the information
encoded in such an emission – and the surveys currently in progress like S-PASS and GMIMS. 相似文献
17.
Riccardo Marson Mauro Pontani Ettore Perozzi Paolo Teofilatto 《Celestial Mechanics and Dynamical Astronomy》2010,106(2):117-142
The possibility of communicating with the far side of the Moon is essential for keeping a continuous radio link with lunar
orbiting spacecraft, as well as with manned or unmanned surface facilities in locations characterized by poor coverage from
Earth. If the exploration and the exploitation of the Moon must be sustainable in the medium/long term, we need to develop
the capability to realize and service such facilities at an affordable cost. Minimizing the spacecraft mass and the number
of launches is a driving parameter to this end. The aim of this study is to show how Space Manifold Dynamics can be profitably
applied in order to launch three small spacecraft onboard the same launch vehicle and send them to different orbits around
the Moon with no significant difference in the Delta-V budgets. Internal manifold transfers are considered to minimize also
the transfer time. The approach used is the following: we used the linearized solution of the equations of motion in the Circular
Restricted Three Body Problem to determine a first–guess state vector associated with the Weak Stability Boundary regions,
either around the collinear Lagrangian point L1 or around the Moon. The resulting vector is then used as initial state in
a numerical backward-integration sequence that outputs a trajectory on a manifold. The dynamical model used in the numerical
integration is four-body and non-circular, i.e. the perturbations of the Sun and the lunar orbital eccentricity are accounted
for. The trajectory found in this way is used as the principal segment of the lunar transfer. After separation, with minor
maneuvers each satellite is injected into different orbits that lead to ballistic capture around the Moon. Finally, one or
more circularization maneuvers are needed in order to achieve the final circular orbits. The whole mission profile, from launch
to insertion into the final lunar orbits, is modeled numerically with the commercial software STK. 相似文献
18.
Remote surface flow observations are crucial for improving the comprehension of hydrological phenomena. A recent advancement in remote hydrological measurements involves the use of drones for generating surface flow‐velocity field maps through large‐scale particle image velocimetry (LSPIV). In this work, we perform a comparative analysis of drone‐based LSPIV with fixed implementations. Quantitative indices are introduced to test the efficiency of the techniques with regards to measurement accuracy, sensitivity to the transit of tracers, and platform mobility. Experimental findings support drone‐based observations in outdoor settings. Specifically, measurements from the aerial platform are more sensitive to the transit of tracers and closer to benchmark values than traditional LSPIV implementations. Future work should aim at improving the stability of the aerial platform and mitigating the effects of tracer scarcity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
19.
20.
Ettore Perozzi Lorenzo Casalino Guido Colasurdo Alessandro Rossi Giovanni B. Valsecchi 《Celestial Mechanics and Dynamical Astronomy》2002,83(1-4):49-62
The authors here propose a mission scenario, aimed at close exploration of a Near-Earth Asteroid, exploiting low-V resonant trajectories. These trajectories allow repeated fly-bys of a chosen target. A selection procedure, which has been used to find some interesting mission opportunities in the 2005-2015 time frame, is described and the corresponding detailed mission profiles are derived, using an indirect optimization method. 相似文献