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The finite element interpretation is discussed of two load tests carried out on instrumented vibro-piles in a granular deposit. A first back analysis, aimed at assessing the improvement of the mechanical characteristics of soil induced by the vibratory construction process, highlights an apparent contradiction between the experimental variation of the axial load along the pile and the numerical results. This suggests introducing as a free variable, in addition to the elastic and shear strength parameters of the granular soil, also the increase of the nominal diameter of pile caused by vibrations. The second back analysis provides some insight into the variation of the diameter with depth and leads to an acceptable interpretation, from the engineering standpoint, of the load tests. On these bases a quantitative comparison is presented between the calculated load–settlement diagram of the vibro-pile and that of a “standard” pile constructed without vibrations in the same granular deposit. 相似文献
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Manuela Rossi Marcella Dell’Aglio Alessandro De Giacomo Rosalba Gaudiuso Giorgio Saverio Senesi Olga De Pascale Francesco Capitelli Fabrizio Nestola Maria Rosaria Ghiara 《Physics and Chemistry of Minerals》2014,41(2):127-140
Gem-quality alexandrite, hiddenite and kunzite, elbaite and topaz minerals were characterized through a multi-methodological investigation based on EMPA-WDS, LA-ICP-MS, and laser-induced breakdown spectroscopy (LIBS). With respect to the others, the latter technique enables a simultaneous multi-elemental composition without any sample preparation and the detection of light elements, such as Li, Be and B. The criteria for the choice of minerals were: (a) the presence of chromophore elements in minor contents and/or as traces; (b) the presence of light lithophile elements (Li, Be and B); (c) different crystal chemistry complexity. The results show that LIBS can be employed in mineralogical studies for the identification and characterization of minerals, and as a fast screening method to determine the chemical composition, including the chromophore and light lithophile elements. 相似文献
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M. Contini 《New Astronomy》2011,16(7):439-444
The visual magnitude profile of the symbiotic system Z And during the 1984–1986 activity period appears double peaked and the flux intensity is low compared to outbursts in other epochs. The detailed modeling of the observed spectra, accounting for the shells ejected by the red giant star, shows that the outburst is intrinsically single but distorted by the collision at different phases of the white dwarf wind with two close shells. 相似文献
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A comparison between the observed UV spectra and detailed consistent calculations of the Cygnus Loop is presented. The results demonstrate that the spectra can be explained by supposing that the Cygnus Loop (C.L.) moves into a fully ionized gas. The [O III]/H ratio is shown to be an indicator to the fraction of He++ in the gas entering the shock.Further results are:(a) Observed shocks of higher velocity propagation move into regions of lower density; (b) the optical and UV spectra are emitted by very close and almost overlapping shocks (c) fast shocks (v240 km s–1) propagation in the intercloud medium produce the X-ray emission, however, they can also produce faint H on impinging interstellar clouds.We find that carbon (CI, CII, CIII, and CIV) depletion relative to other heavy elements is not more than a factor 3; whereas, we confirm that all heavy elements, relative to their solar abundance, are depleted by a factor 10. Heavy elemental depletion is likely to result formation of grains, sputtering and molecules in ISM. 相似文献
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D. Cesari D. Contini A. Genga M. Siciliano C. Elefante F. Baglivi L. Daniele 《Applied Geochemistry》2012
In this work, the inorganic chemical profiles of soil samples collected at different sites in the Salentum peninsula (Italy, Apulia region) are discussed. The samples were re-suspended in the laboratory, for PM10 sampling, using a ventilated wooden chamber and were then chemically analysed measuring the abundances of 17 elements. Different land use categories of soils (olive grove, arable land, vineyards, sand, and urban dust) were included in the 50 samples analysed: 45 collected in background areas and five collected in the urban area of Lecce. The objectives were to compare the chemical profiles of raw soil and re-suspended PM10 for different crustal sources and to estimate the potential improvements in the calculation of the enrichment factors of atmospheric PM10. The variability of elemental abundances in samples of the same category of soil collected in different zones was of the same order of magnitude as the differences observed between the various categories of soil. This allows the calculation of a weighted average composition of soil and urban dust and the corresponding weighted average composition of re-suspended PM10. In re-suspended PM10 from average background soil, all of the elements except Ca, Na, K and V have larger abundances with respect to raw soil. In urban dust, this is limited to Ca, V and Mg. The crustal enrichment factors (EFs) of atmospheric PM10 were evaluated by considering different reference elements and different reference tables. Results indicated that it is possible to apply a two-threshold (S1 and S2) scheme for the interpretation of EF, with thresholds derived from uncertainty in soil categories and from the choice of the reference element. A specific element is likely of crustal origin if EF < S1 and likely of anthropogenic origin if EF > S2. Between the two thresholds, the element can be considered of mixed origin. The thresholds vary according to the geological composition used in the evaluation of EF. If the average composition of local re-suspended soils is used, the thresholds are S1 = 2 and S2 = 4. If raw soil is used, the thresholds become S1 = 5 and S2 = 10. If the average upper-crust composition from literature data is used, the thresholds further increase to S1 = 10 and S2 = 20. 相似文献
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Angelo Peccerillo Marcella Federico Mauro Brilli 《Geochimica et cosmochimica acta》2010,74(10):2999-95
Magma-carbonate rock interaction is investigated through a geochemical and Sr-Nd-O isotope study of granular lithic clasts (ejecta) from the Alban Hills ultrapotassic volcano, Central Italy. Some samples (Group-1) basically represent intrusive equivalents of Alban Hills magmas. A few samples (Group-2) are ultramafic, have high MgO (∼30 to 40 wt%) and δ18O‰, and originated by accumulation of mafic phases that crystallised from ultrapotassic melts during assimilation of dolomitic rocks. Group-3 ejecta consist of dominant K-feldspar, and show major element compositions similar to phonolites, which, however, are absent among the Alban Hills volcanics. Finally, another group (Group-4) contains corroded K-feldspars, surrounded by a microgranular to porphyritic matrix, made of igneous minerals (K-feldspar, foids, clinopyroxene, phlogopite) plus wollastonite, garnet, and some cuspidine. Group-4 ejecta are depleted in SiO2 and enriched in CaO with respect to Group-3.The analysed ejecta have similar 143Nd/144Nd (0.51204-0.51217) as the Alban Hills lavas, whereas 87Sr/86Sr (0.70900-0.71067) is similar to lower. Whole rocks δ18O‰ ranges from +7.0 to +13.2, reaching maximum values in ultramafic samples. A positive correlation with CaO is observed in single rock groups. Large Ion Lithophile Element (LILE) abundances and REE fractionation are generally high, and extreme values of Th, U and LREE are found in some Group-3 and Group-4 rocks.Mineralogical, petrological and geochemical data reveal extensive interaction between magma and carbonate wall rocks, involving both dolostones and limestones. These processes had dramatic effects on magma compositions, especially on phonolites, which were transformed to foidites. Evidence of such a process is found in Group-4 samples, in which K-feldspar is observed to react with a matrix that represents strongly undersaturated melts formed by interaction between silicate magma and carbonates. Trace element data also testify to a very important role for F-CO2-H2O-S fluids during magma-wall rock interaction. Fluid transfer was responsible for extreme enrichments in Th, U, and LREE especially observed in Group-3 and Group-4 rocks. Implications of these processes for potassic magma evolution in Central Italy are discussed. 相似文献
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The Planck On-the-Flight Forecaster (POFF) is a tool to predict when a position in the sky will be within a selected angular distance from any instrument receiver direction in the Planck satellite taking into consideration its programmed observational plan. The tool has been developed in the framework of the Planck LFI Core Team activities, but it is now used by the whole Planck collaboration.In this paper we describe the tool and its applications to plan observations of point sources with other instruments which are expected to increase the scientific importance of Planck data, once they are publicly available. Collecting simultaneous multi-frequency data, like those that can be planned with the POFF, will aid the investigation of variability in point sources and also allow the reconstruction of point source spectral energy distributions over wide frequency range, thus minimizing the effect of variability itself.POFF is a combination of IDL routines which combine the publicly available information about the Planck scanning strategy with the focal plane shape to identify if a given (list of) position(s) could be observed by the satellite at a given frequency and/or by selected receivers in a given time range. The output can be displayed with any reasonable desired time resolution and with various sorting options.The code is not a Planck product, but has been validated with the Planck LFI pipeline, by searching for sources in the first satellite datasets. It has been implemented as one of the general tools of the LFI Data Processing Center. The code format and its large number of options make the program flexible and suitable for many applications, facilitating fast results.POFF is currently successfully used to plan activities within the Planck collaboration, including observations with several ground-based facilities, and is also available to the larger scientific community. 相似文献
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