Steeper biomass spectra of demersal fish communities after trawler exclusion in Sicily     

Sweeting  Christopher J.; Badalamenti  Fabio; D'Anna  Giovanni; Pipitone  Carlo; Polunin  N. V. C. 《ICES Journal of Marine Science》2009,66(1):195-202

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Editorial     

Giovanni Barla 《Rock Mechanics and Rock Engineering》2014,47(5):1517-1517

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Rapid estimation of ground-shaking maps for seismic emergency management in the Campania Region of southern Italy   总被引：1，自引：1，他引：0  

Vincenzo Convertito  Raffaella De Matteis  Luciana Cantore  Aldo Zollo  Giovanni Iannaccone  Mauro Caccavale 《Natural Hazards》2010,52(1):97-115

Strong ground-shaking mapping soon after a moderate-to-large earthquake is crucial to recognize the areas that have suffered the largest damage and losses. These maps have a fundamental role for emergency services, loss estimation and planning of emergency actions by the Civil Protection Authorities. This is particularly important for areas with high seismic risk levels, such as the Campania-Lucania Region in southern Italy. Taking advantage of the Irpinia Seismic Network (ISNet), a recently installed dense and wide dynamic seismic network, we have developed a procedure for rapid estimation of ground-shaking maps after moderate-to-large earthquakes (GRSmap). This uses an optimal data gridding scheme designed to account for bi-dimensional features of strong ground-motion fields, such as directivity, radiation patterns and focal mechanisms, to which most damage can be correlated. The basis of the mapping technique is a triangulation procedure to locally correct predicted data at the triangle barycentres where their vertices correspond to seismic stations. The method has been tested off-line using a simulated M 6.6 earthquake located at the centre of ISNet and applied to data of the 23 November 1980 Irpina M 6.9 earthquake recorded by a sparse network. This has highlighted its ability to predict peak ground-motion parameters of large magnitude earthquakes with respect to the attenuation relationships.  相似文献   

Simulating the role of tides and sediment characteristics on tidal flat sorting and bedding dynamics     

Zeng Zhou  Qian Liu  Daidu Fan  Giovanni Coco  Zheng Gong  Iris Möller  Fan Xu  Ian Townend  Changkuan Zhang 《地球表面变化过程与地形》2021,46(11):2163-2176

Understanding sediment sorting and bedding dynamics has high value to unravelling the mechanisms underlying geomorphological, geological, ecological and environmental imprints of tidal wetlands and hence to predicting their future changes. Using the Nanhui tidal flat on the Changjiang (Yangtze) Delta, China, as a reference site, this study establishes a schematized morphodynamic model coupling flow, sediment dynamics and bed level change to explore the processes that govern sediment sorting and bedding phenomena. Model results indicate an overall agreement with field data in terms of tidal current velocities, suspended sediment concentrations (SSCs), deposition thicknesses and sedimentary structures. Depending on the variation of tidal current strength, sand-dominated layers (SDLs) and mud-dominated layers (MDLs) tend to form during spring and neap tides, respectively. Thinner tidal couplets are developed during daily scale flood–ebb variations. A larger tidal level variation during a spring–neap tidal cycle, associated with a stronger tidal current variation, favours the formation of SDLs and tidal couplets. A larger boundary sediment supply generally promotes the formation of tidal bedding, though the bedding detail is partially dependent on the SSC composition of different sediment types. Sediment properties, including for example grain size and settling velocity, are also found to influence sediment sorting and bedding characteristics. In particular, finer and coarser sediment respond differently to spring and neap tides. During neap tides, relatively small flow velocities favour the deposition of finer sediment, with limited coarser sediment being transported to the upper tidal flat because of the larger settling velocity. During spring tides, larger flow velocities transport more coarser sediment to the upper tidal flat, accounting for distinct lamination formation. Model results are qualitatively consistent with field observations, but the role of waves, biological processes and alongshore currents needs to be included in further studies to establish a more complete understanding.  相似文献   

A wideband multirate FFT spectrometer with highly uniform response     

Giovanni Comoretto  Andrea Melis  Gino Tuccari 《Experimental Astronomy》2011,31(1):59-68

An integrating spectrometer based on a two-stage polyphase digital filter bank (PDFB) algorithm is described. The first PDFB operates on a time multiplexed wideband signal, with a bandwidth up to 1 GHz. The second PDFB is performed in parallel over couples of overlapping channels from the first filterbank. The design automatically deletes the unused portions of the first filterbank channels, providing a seamless, uniform channelization of the input band. The design has been implemented and tested on the VLBI DBBC platform, using a single Xilinx XC5VLX220 FPGA.  相似文献   

Artificial equilibrium points for a generalized sail in the circular restricted three-body problem     

Generoso Aliasi  Giovanni Mengali  Alessandro A. Quarta 《Celestial Mechanics and Dynamical Astronomy》2011,110(4):343-368

This paper introduces a new approach to the study of artificial equilibrium points in the circular restricted three-body problem for propulsion systems with continuous and purely radial thrust. The propulsion system is described by means of a general mathematical model that encompasses the behavior of different systems like a solar sail, a magnetic sail and an electric sail. The proposed model is based on the choice of a coefficient related to the propulsion type and a performance parameter that quantifies the system technological complexity. The propulsion system is therefore referred to as generalized sail. The existence of artificial equilibrium points for a generalized sail is investigated. It is shown that three different families of equilibrium points exist, and their characteristic locus is described geometrically by varying the value of the performance parameter. The linear stability of the artificial points is also discussed.  相似文献   

Site-aspect influence on climate sensitivity over time of a high-altitude Pinus cembra tree-ring network   总被引：1，自引：0，他引：1  

Giovanni Leonelli  Manuela Pelfini  Giovanna Battipaglia  Paolo Cherubini 《Climatic change》2009,96(1-2):185-201

Recently a divergence between tree-ring parameters from temperature-limited environments and temperature records has been observed worldwide but comprehensive explanations are still lacking. From a dendroclimatic analysis performed on a high-altitude tree-ring network of Pinus cembra (L.) in the Central Italian Alps we found that site aspect influences non-stationary growth-climate relationships over time. A general increasing divergence between ring width and the summer temperature record (J–A) has been observed especially for chronologies from SW-facing slopes, whereas chronologies from N-facing sites showed stable relationships over time. The monthly analysis revealed that the decrease in sensitivity was mostly accounted for by the changes in the relationships with June temperature (decreasing correlations especially for S- and W-facing site chronologies), whereas trees from N-facing sites showed an increasing sensitivity to July temperatures. Our data suggest that at high altitudes, low temperatures at the beginning of the growing season no longer limit growth. We also found that our temperature-sensitive trees did not linearly respond in radial growth to the extreme heat event of summer 2003, and formed an annual ring of average width, resulting in a strong divergence from the temperature record. Our findings underline the importance of site ecology for tree-ring based climate reconstructions using temperature-sensitive ring-width chronologies, and may help in solving the ‘divergence problem’.  相似文献   

A vision for space science     

Giovanni F. Bignami 《Experimental Astronomy》2009,23(1):1-3

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Non-Keplerian orbits for electric sails   总被引：1，自引：0，他引：1  

Giovanni Mengali  Alessandro A. Quarta 《Celestial Mechanics and Dynamical Astronomy》2009,105(1-3):179-195

An electric sail is capable of guaranteeing the fulfilment of a class of trajectories that would be otherwise unfeasible through conventional propulsion systems. In particular, the aim of this paper is to analyze the electric sail capabilities of generating a class of displaced non-Keplerian orbits, useful for the observation of the Sun’s polar regions. These orbits are characterized through their physical parameters (orbital period and solar distance) and the spacecraft propulsion capabilities. A comparison with a solar sail is made to highlight which of the two systems is more convenient for a given mission scenario. The optimal (minimum time) transfer trajectories towards the displaced orbits are found with an indirect approach.  相似文献   

“Galileo Galilei” (GG) a small satellite to test the equivalence principle of Galileo, Newton and Einstein     

Anna M. Nobili  Gian Luca Comandi  Suresh Doravari  Donato Bramanti  Rajeev Kumar  Francesco Maccarrone  Erseo Polacco  Slava G. Turyshev  Michael Shao  John Lipa  Hansjoerg Dittus  Claus Laemmerzhal  Achim Peters  Jurgen Mueller  C. S. Unnikrishnan  Ian W. Roxburgh  Alain Brillet  Christian Marchal  Jun Luo  Jozef van der Ha  Vadim Milyukov  Valerio Iafolla  David Lucchesi  Paolo Tortora  Paolo De Bernardis  Federico Palmonari  Sergio Focardi  Dino Zanello  Salvatore Monaco  Giovanni Mengali  Luciano Anselmo  Lorenzo Iorio  Zoran Knezevic 《Experimental Astronomy》2009,23(2):689-710

“Galileo Galilei” (GG) is a small satellite designed to fly in low Earth orbit with the goal of testing the Equivalence Principle—which is at the basis of the General Theory of Relativity—to 1 part in 10¹⁷. If successful, it would improve current laboratory results by 4 orders of magnitude. A confirmation would strongly constrain theories; proof of violation is believed to lead to a scientific revolution. The experiment design allows it to be carried out at ambient temperature inside a small 1-axis stabilized satellite (250 kg total mass). GG is under investigation at Phase A-2 level by ASI (Agenzia Spaziale Italiana) at Thales Alenia Space in Torino, while a laboratory prototype (known as GGG) is operational at INFN laboratories in Pisa, supported by INFN (Istituto Nazionale di fisica Nucleare) and ASI. A final study report will be published in 2009.  相似文献