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Autonomous underwater vehicle teams for adaptive ocean sampling: a data-driven approach 总被引:1,自引:1,他引:0
Andrea?MunafòEmail author Enrico?Simetti Alessio?Turetta Andrea?Caiti Giuseppe?Casalino 《Ocean Dynamics》2011,61(11):1981-1994
The current technological developments in autonomous underwater vehicles (AUVs) and underwater communication have nowadays
allowed to push the original idea of autonomous ocean sampling network even further, with the possibility of using each agent
of the network not only as an operative component driven by external commands (model-driven) but as a reactive element able
to act in response to changing conditions as measured during the exploration (data-driven). With this paper, we propose a
novel data-driven algorithm for AUVs team for adaptive sampling of oceanic regions, where each agent shares its knowledge
of the environment with its teammates and autonomously takes decision in order to reconstruct the desired oceanic field. In
particular, sampling point selection is made in order to minimize the uncertainty in the estimated field while keeping communication
contact with the rest of the team and avoiding to repeatedly sampling sub-regions already explored. The proposed approach
is based on the use of the emergent behaviour technique and on the use of artificial potential functions (interest functions)
to achieve the desired goal at the end of the mission. In this way, there is no explicit minimization of a cost functional
at each decision step. The oceanic field is reconstructed by the application of radial basis functions interpolation of irregularly
spaced data. A simulative example for the estimation of a salinity field with sea data obtained using the Mediterranean Sea
Forecasting System is shown in the paper, in order to investigate the effect of the different uncertainty sources, including
sea currents, on the behaviour of the exploration team and ultimately on the reconstruction of the salinity field. 相似文献
277.
Tephrochronological study in the quaternary Val d’Agri intermontane basin (Southern Apennines,Italy)
Irene Zembo Pietro Vignola Sergio Andò Riccardo Bersezio Luigina Vezzoli 《International Journal of Earth Sciences》2011,100(1):173-187
In the south-eastern depocentre of the Val d’Agri basin (Southern Apennines), a volcanic ash layer crops out interbedded within
poorly structured alluvial fan deposits of Late Pleistocene age. Textural, depositional and pedological features of this weathered
layer suggest a primary deposition from a pyroclastic fall-out of volcanic ash. Chemical analyses of feldspars show an alkali
trachytic composition and accessory minerals association allow to correlate this tephra layer with the regionally dispersed
Y-7 marine tephra layer (Tufo Verde Epomeo eruption, Ischia volcano), dated at 56 ± 4 ka. The Val d’Agri tephra here described
for the first time was deposited during MIS Stage 3. Its recovery and characterization permit to contribute to regional correlation
of the Mediterranean climatic and volcanic events from marine to continental successions and to describe landscape evolution
of the Southern Apennines during glacial–interglacial cycles. 相似文献
278.
A. Vaivads G. Andersson S. D. Bale C. M. Cully J. De Keyser M. Fujimoto S. Grahn S. Haaland H. Ji Yu. V. Khotyaintsev A. Lazarian B. Lavraud I. R. Mann R. Nakamura T. K. M. Nakamura Y. Narita A. Retinò F. Sahraoui A. Schekochihin S. J. Schwartz I. Shinohara L. Sorriso-Valvo 《Experimental Astronomy》2012,33(2-3):491-527
We describe the mission concept of how ESA can make a major contribution to the Japanese Canadian multi-spacecraft mission SCOPE by adding one cost-effective spacecraft EIDO (Electron and Ion Dynamics Observatory), which has a comprehensive and optimized plasma payload to address the physics of particle acceleration. The combined mission EIDOSCOPE will distinguish amongst and quantify the governing processes of particle acceleration at several important plasma boundaries and their associated boundary layers: collisionless shocks, plasma jet fronts, thin current sheets and turbulent boundary layers. Particle acceleration and associated cross-scale coupling is one of the key outstanding topics to be addressed in the Plasma Universe. The very important science questions that only the combined EIDOSCOPE mission will be able to tackle are: 1) Quantitatively, what are the processes and efficiencies with which both electrons and ions are selectively injected and subsequently accelerated by collisionless shocks? 2) How does small-scale electron and ion acceleration at jet fronts due to kinetic processes couple simultaneously to large scale acceleration due to fluid (MHD) mechanisms? 3) How does multi-scale coupling govern acceleration mechanisms at electron, ion and fluid scales in thin current sheets? 4) How do particle acceleration processes inside turbulent boundary layers depend on turbulence properties at ion/electron scales? EIDO particle instruments are capable of resolving full 3D particle distribution functions in both thermal and suprathermal regimes and at high enough temporal resolution to resolve the relevant scales even in very dynamic plasma processes. The EIDO spin axis is designed to be sun-pointing, allowing EIDO to carry out the most sensitive electric field measurements ever accomplished in the outer magnetosphere. Combined with a nearby SCOPE Far Daughter satellite, EIDO will form a second pair (in addition to SCOPE Mother-Near Daughter) of closely separated satellites that provides the unique capability to measure the 3D electric field with high accuracy and sensitivity. All EIDO instrumentation are state-of-the-art technology with heritage from many recent missions. The EIDOSCOPE orbit will be close to equatorial with apogee 25-30 RE and perigee 8-10 RE. In the course of one year the orbit will cross all the major plasma boundaries in the outer magnetosphere; bow shock, magnetopause and magnetotail current sheets, jet fronts and turbulent boundary layers. EIDO offers excellent cost/benefits for ESA, as for only a fraction of an M-class mission cost ESA can become an integral part of a major multi-agency L-class level mission that addresses outstanding science questions for the benefit of the European science community. 相似文献
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P. D. Pant Ritu Chauhan S. S. Bhakuni 《Journal of the Geological Society of India》2012,79(5):429-448
Along the North Almora Thrust (NAT) in the Kumaun Lesser Himalaya, a zone of mylonitic rocks has developed due to strain localization during the tectonic emplacement of the Almora Nappe over the Lesser Himalayan Sequence. This zone is referred here as the NAT zone (NATZ) that is dissected by faults, which are transverse to the Himalayan orographic trend and are known as seismically active structures. Trending NNW-SSE these are the Chaukhutiya and Raintoli faults. Two E-W oriented subsidiary brittle faults across the Chaukhutiya Fault are also recognized. Based on the field study and magnetic fabric analysis an attempt has been made to evaluate the deformation and kinematic history of northeastern margin of the Almora Nappe superposed by the Chaukhutiya faulting that coincides with northeastern margin of the NAT. Field study reveals brittle-ductile and brittle regimes of deformation along the Chaukhutiya Fault. Away from the NAT variable attitudes (E-W or ENE-WSW with gentle dip) of field foliation and axial planes of folds are observed, whereas at and near the NAT the attitudes of beds, including curved lithounits, are steeply dipping and are oriented parallel with the NNW-SSE trending NAT. Curvature in fold hinge line and discontinuous occurrence of lithounits are observed along the fault. 相似文献