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L. Crivellari U. Flora M. Mercanti C. Morossi L. Rusconi G. Sedmak 《Astrophysics and Space Science》1981,80(2):425-436
We present an identification list for the visible spectra of three B stars: π Cet (B7V), 36 Lyn B8 IIIp (?)),and 134 Tau (B9 IV). Equivalent widths have been measured on medium dispersion plates (7.0 and 12.4 Å mm?1) taken with the 152 cm coudé reflector at the Observatoire de Haute Provence (France). These results are also presented. The photographic plates were digitized by using a PDS 1010A microdensitometer. The spectroscopic data were reduced by means of a dedicated software package and an attempt was made to compute equivalent widths in a homogeneous way. T eff and logg parameters were estimated by using the computer to compare automatically the spectroscopic data with the value of theoretical models. 相似文献
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Norman K. Grant James L. Powell Flora R. Burkholder John V. Walther Max L. Coleman 《Earth and Planetary Science Letters》1976,31(2):209-223
Strontium and oxygen isotope measurements on the alkali basalt-trachyte-phonolite suite of St. Helena show that some of the late-fractionated rocks are enriched in 87Sr and depleted in 18O relative to the older basalts. The data rule out both the formation of the late-fractionated rocks by the partial melting of hydrothermally altered oceanic crust and the contamination of the volcanic rocks by oceanic sediment. It also appears to be incompatible with models based either on the melting of previously fractionated and crystallized liquids in the volcanic pile, or the long-term fractionation of lavas over several millions of years in a sub-volcanic magma chamber.It is concluded that hydrothermal interaction with meteoric water is the most important cause of the 18O depletion. If the interaction occurred at widely differing temperatures, and involved meteoric and seawaters, it might conceivably have caused both the oxygen and strontium isotope heterogeneities. 相似文献
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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
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The walls of a deep excavation in cohesionless soils below the water table have been supported by a reinforced concrete diaphragm with T-shaped panels. To improve the safety against the risk of local collapse during the panel excavation, the soil surrounding the panels has been treated by deep mixing to a depth of 6?C10?m. The horizontal displacements, induced in the surrounding soil by the installation (deep mixing, slurry supported excavation, placing of the reinforcement cage, concrete casting and curing) of the diaphragm, have been measured by means of inclinometers. It is claimed that they can be a significant fraction of the total displacements induced by the excavation. A back analysis of the observed displacements shows that the deformation process is essentially elastic and can be satisfactorily modelled provided the values of the soil stiffness are properly selected. 相似文献
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For most of the year, a dry‐bed desert wash is void of water flow. Intensive rain events, however, could trigger significant flash floods that bring about highly complicated hydrodynamics and morphodynamics processes within a desert stream. We present a fully coupled three‐phase flow model of air, water, and sediment to simulate numerically the propagation of a flash flood in a field‐scale fluvial desert stream, the so‐called Tex Wash located in the Mojave Desert, California, United States. The turbulent flow of the flash flood is computed using the three‐dimensional unsteady Reynolds‐averaged Navier–Stokes equations closed with the shear stress transport k ? ω model. The free surface of the flash flood at the interface of air and water phases is computed with the level‐set method, which enables instantaneous tracking of the water surface as the flash flood propagates over the dry bed of the desert stream. The evolution of the desert fluvial stream's morphology, due to the action of the propagating flash flood on the mobile bed, is calculated using a Eulerian morphodynamics model based on the curvilinear immersed boundary method. The capabilities of the proposed numerical framework are demonstrated by applying it to simulate a flash flood event in a 0.65‐km ‐long reach of the Tex Wash, the intricate channel morphology of which is obtained using light imaging detection and ranging technology. The simulated region of the stream includes a number of bridge foundations. The simulation results of the model for the flash flood event revealed the formation of a highly complex flow field and scour patterns within the stream. Moreover, our simulation results showed that most scour processes take place during the steady phase of the flash flood, that is, after the flash flood fills the stream. The transient phase of the flash flood is rather short and contributes to a very limited amount of erosion within the desert stream. 相似文献
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Sonja Jankowfsky Flora Branger Isabelle Braud Jorge Gironás Fabrice Rodriguez 《水文研究》2013,27(25):3747-3761
Suburban areas are subject to strong anthropogenic modifications, which can influence hydrological processes. Sewer systems, ditches, sewer overflow devices and retention basins are introduced and large surface areas are sealed off. The knowledge of accurate flow paths and watershed boundaries in these suburban areas is important for storm water management, hydrological modelling and hydrological data analysis. This study proposes a new method for the determination of the drainage network based on time efficient field investigations and integration of sewer system maps into the drainage network for small catchments of up to 10 km2. A new method is also proposed for the delineation of subcatchments and thus the catchment area. The subcatchments are delineated using a combination of an object‐oriented approach in the urban zone and geographical information system–based terrain analysis with flow direction forcing in the rural zone. The method is applied to the Chaudanne catchment, which belongs to the Yzeron river network and is located in the suburban area of Lyon, France. The resulting subcatchment map gives information about subcatchment response and contribution. The method is compared with six other automatic catchment delineation methods based on stream burning, flow direction forcing and calculation of subcatchments for inlet points. None of the automatic methods could correctly represent the catchment area and flow paths observed in the field. The watershed area calculated with these methods differs by as much as 25% from the area computed with the new method. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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A comprehensive parametric study on the inelastic seismic response of seismically isolated RC frame buildings, designed for gravity loads only, is presented. Four building prototypes, with 23 m × 10 m floor plan dimensions and number of storeys ranging from 2 to 8, are considered. All the buildings present internal resistant frames in one direction only, identified as the strong direction of the building. In the orthogonal weak direction, the buildings present outer resistant frames only, with infilled masonry panels. This structural configuration is typical of many existing RC buildings, realized in Italy and other European countries in the 60s and 70s. The parametric study is based on the results of extensive nonlinear response‐time history analyses of 2‐DOF systems, using a set of seven artificial and natural seismic ground motions. In the parametric study, buildings with strength ratio (Fy/W) ranging from 0.03 to 0.15 and post‐yield stiffness ratio ranging from 0% to 6% are examined. Three different types of isolation systems are considered, that is, high damping rubber bearings, lead rubber bearings and friction pendulum bearings. The isolation systems have been designed accepting the occurrence of plastic hinges in the superstructure during the design earthquake. The nonlinear response‐time history analyses results show that structures with seismic isolation experience fewer inelastic cycles compared with fixed‐base structures. As a consequence, although limited plastic deformations can be accepted, the collapse limit state of seismically isolated structures should be based on the lateral capacity of the superstructure without significant reliance on its inherent hysteretic damping or ductility capacity. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Sebastiano Foti Fabrice Hollender Flora Garofalo Dario Albarello Michael Asten Pierre-Yves Bard Cesare Comina Cécile Cornou Brady Cox Giuseppe Di Giulio Thomas Forbriger Koichi Hayashi Enrico Lunedei Antony Martin Diego Mercerat Matthias Ohrnberger Valerio Poggi Florence Renalier Deborah Sicilia Valentina Socco 《Bulletin of Earthquake Engineering》2018,16(6):2367-2420
Surface wave methods gained in the past decades a primary role in many seismic projects. Specifically, they are often used to retrieve a 1D shear wave velocity model or to estimate the VS,30 at a site. The complexity of the interpretation process and the variety of possible approaches to surface wave analysis make it very hard to set a fixed standard to assure quality and reliability of the results. The present guidelines provide practical information on the acquisition and analysis of surface wave data by giving some basic principles and specific suggestions related to the most common situations. They are primarily targeted to non-expert users approaching surface wave testing, but can be useful to specialists in the field as a general reference. The guidelines are based on the experience gained within the InterPACIFIC project and on the expertise of the participants in acquisition and analysis of surface wave data. 相似文献