Cosmic stellar relics in the Galactic halo     

Stefania Salvadori  Raffaella Schneider  Andrea Ferrara 《Monthly notices of the Royal Astronomical Society》2007,381(2):647-662

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Comparison of spectral characteristics of precipitation from radar estimates and COSMO-model predicted fields     

Matteo Willeit  Roberta Amorati  Andrea Montani  Valentina Pavan  Maria Stefania Tesini 《Meteorology and Atmospheric Physics》2015,127(2):191-203

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Excited lines in the H and K region of Ca ii in the solar flare on March 12, 1969     

Gallegos  H. Grossi  Molnar  H.  Seibold  J. R. 《Solar physics》1971,16(1):120-124

Many excited lines and a remarkable emission in the continuum were observed in the region around the H and K lines during a strong flare.  相似文献   

The loop prominence of May 13, 1971 and its associated effects     

M. E. Machado  H. Grossi Gallegos  A. F. Silva 《Solar physics》1972,25(2):402-412

A study is presented of the formation of a loop prominence system (LPS) on May 13, 1971. The development of the phenomenon is found to be consistent with the model of Jefferies and Orrall, and was associated with small radio bursts and several kind of SID. From the spectral analysis a temperature of 13200 K has been deduced and a density of hydrogen atoms n(H) 10¹⁰cm^-3 estimated. The existence of inclined emissions probably produced by rotatory motions is discussed. From the radio data analysis it was inferred that an impulsive and a thermal component were present; the length of the emitting plasma cloud was found to be about 56000 km. The LPS appeared, in accordance with previous results, in a region producing proton flares.  相似文献   

Spaceborne long vertical wire as a self-powered ULF/ELF radiator     

Grossi  M. 《Oceanic Engineering, IEEE Journal of》1984,9(3):211-213

In December 1987, on the occasion of the first demonstration flight of the shuttle-borne Tethered Satellite System (T.S.S.), NASA will deploy in orbit a 20-km vertical conducting wire (electrodynamic tether) and will test, among other things, the wire's ability to function as generator of de electric power, through thenu times Bmechanism of interaction, as well as its capability to operate as a serf-powered radiator of ultra-low frequency/ extremely low frequency waves (ULF/ELF), through such mechanisms as the Alfvén Wings. The wire's ability to generate dc electric power up to the 100 kW level has been investigated by several authors and it is now considered to be a reasonable expectation. Concerning the wire's ability to radiate ULF/ELF waves, rigorous analytical evidence still has to be worked out. The expectation at this time is that this vertical radiator may be able to inject from above into the earth-ionosphere transmission line about 10 W at night and10^{-1}by day. Thus in the "hot spot" on the earth's surface, directly underneath (in a magneto-conjugate sense) the orbiting system, signal-to-noise ratios of practical interest may be achievable against natural micropulsation noise. The tether's ability to excite from above long-range propagation modes in the earth-ionosphere transmission line has still to be verified analytically. It is expected that by 1987-1989, comprehensively analytical and experimental evidence will be available to the ULF/ELF community, so that conclusions may be drawn as to the feasibility of strategic communications using orbiting wires. The advantage of the spaceborne placement for the ULF/ELF radiator, compared with the traditional ground-based placement, may be the avoidance of the potential environmental threat posed by the conventional siting.  相似文献   

Large-scale non-Gaussian mass function and halo bias: tests on N-body simulations     

M. Grossi  L. Verde  C. Carbone  K. Dolag  E. Branchini  F. Iannuzzi  S. Matarrese  L. Moscardini 《Monthly notices of the Royal Astronomical Society》2009,398(1):321-332

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Gravitational wave backgrounds and the cosmic transition from Population III to Population II stars     

Stefania Marassi  Raffaella Schneider  Valeria Ferrari 《Monthly notices of the Royal Astronomical Society》2009,398(1):293-302

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Momentum- and Heat-Flux Parametrization at Dome C,Antarctica: A Sensitivity Study     

Etienne Vignon  Christophe Genthon  Hélène Barral  Charles Amory  Ghislain Picard  Hubert Gallée  Giampietro Casasanta  Stefania Argentini 《Boundary-Layer Meteorology》2017,162(2):341-367

An extensive meteorological observational dataset at Dome C, East Antarctic Plateau, enabled estimation of the sensitivity of surface momentum and sensible heat fluxes to aerodynamic roughness length and atmospheric stability in this region. Our study reveals that (1) because of the preferential orientation of snow micro-reliefs (sastrugi), the aerodynamic roughness length \(z_{0}\) varies by more than two orders of magnitude depending on the wind direction; consequently, estimating the turbulent fluxes with a realistic but constant \(z_{0}\) of 1 mm leads to a mean friction velocity bias of \(24\,\%\) in near-neutral conditions; (2) the dependence of the ratio of the roughness length for heat \(z_{0t}\) to \(z_{0}\) on the roughness Reynolds number is shown to be in reasonable agreement with previous models; (3) the wide range of atmospheric stability at Dome C makes the flux very sensitive to the choice of the stability functions; stability function models presumed to be suitable for stable conditions were evaluated and shown to generally underestimate the dimensionless vertical temperature gradient; as these models differ increasingly with increases in the stability parameter z / L, heat flux and friction velocity relative differences reached \(100\,\%\) when \(z/L > 1\); (4) the shallowness of the stable boundary layer is responsible for significant sensitivity to the height of the observed temperature and wind data used to estimate the fluxes. Consistent flux results were obtained with atmospheric measurements at heights up to 2 m. Our sensitivity study revealed the need to include a dynamical parametrization of roughness length over Antarctica in climate models and to develop new parametrizations of the surface fluxes in very stable conditions, accounting, for instance, for the divergence in both radiative and turbulent fluxes in the first few metres of the boundary layer.  相似文献   

Assessment of water vapor retrievals from a GPS receiver network     

Stefania Bonafoni  Augusto Mazzoni  Domenico Cimini  Mario Montopoli  Nazzareno Pierdicca  Patrizia Basili  Piero Ciotti  Giovanni Carlesimo 《GPS Solutions》2013,17(4):475-484

We present an assessment of a GPS receiver operational network to produce accurate integrated precipitable water vapour (IPWV) during a two-week field experiment carried out in Central Italy around the city of Rome, where different instruments were operative. This experimental activity provided an excellent opportunity to compare the GPS products with independent measurements provided by ground-based and space-based sensors and to evaluate their quality in terms of absolute accuracy of IPWV, analyzing also the spatial scale of GPS estimates. For instance, the assimilation into Numerical Weather Prediction models of IPWV provided by a GPS network or its exploitation in space geodesy applications to correct tropospheric effects requires an accuracy in the order of 0.1 cm to be ascribed to IPWV observations. In this work, we assessed that the accuracy for GPS IPWV estimates is 0.07 cm. Moreover, this experiment has pointed out strengths and limitations of an operational network for the water vapor estimation, such as a proper receiver distribution to achieve the desired spatial resolution and a coverage of GPS stations in both flat and mountains regions.  相似文献   

Experimental Evidences of the Effect of Fibres in Reinforcing a Sandy Gravel     

Stefania Lirer  Alessandro Flora  Nilo Cesar Consoli 《Geotechnical and Geological Engineering》2012,30(1):75-83

Studies regarding fibre-reinforcement are restricted to clays, silty and sandy soils. No information is available on gravels. It is worth checking the effect of randomly oriented discrete fibres also on such soils to see if they can be beneficial and to get a better insight into the grain to soil interaction mechanism. In this paper, the effect of a small amount of fibres having high aspect ratio on a sandy gravel was analysed by means of tests carried out in a large triaxial apparatus. Specimens of both natural and fibre-reinforced sandy gravel were prepared by wet tamping at different relative densities, and were tested along monotonic and cyclic stress paths. The results show that the addition of a small amount of fibres causes a slight increase in peak strength and a larger increase in ultimate strength at small confining stress, with an overall more ductile behaviour. The cyclic tests at small confining stress and intermediate strain levels show that, for the lowest applied strain (of the order of 10⁻²%), the stiffness was larger for the reinforced specimens, with a much sharper decrease at larger strains and final values similar for the reinforced and non-reinforced materials.  相似文献