Nucleosynthesis and early chemical evolution in galaxies     

Stelios A Tsangarides  Enrico Arnone  Sean G Ryan 《Astronomy& Geophysics》2003,44(2):2.28-2.29

Nucleosynthesis and galactic chemical evolution are inter-linked topics that merge various fields in astronomy and physics. Speakers at the RAS discussion meeting of January 2003 combined theory and observation in understanding these fields. Stelios A Tsangarides, Enrico Arnone and Sean G Ryan report.  相似文献   

Effects of reinforcement slippage on the non‐linear response under cyclic loadings of RC frame structures     

Suchart Limkatanyu  Enrico Spacone 《地震工程与结构动力学》2003,32(15):2407-2424

This paper discusses the importance of including the bond‐slip effects in assessing the response under cyclic loads of reinforced concrete frames. The discussion is based on analyses performed using numerical models which are simple, computationally efficient and capable of representing the salient features of reinforced concrete frames under both static and dynamic loads. The numerical models comprise a displacement‐based, reinforced concrete frame element with bond‐slip and a rigid beam column joint element with bond‐slip. Two applications illustrate the model accuracy and show the importance of including bond‐slip. The first application considers a reinforced concrete beam‐column subassemblage experimentally tested under cyclic loads. The second application considers the shaking table test of a two‐story one‐bay reinforced concrete frame In both cases the analytical results correlate well with the experimental results in terms of strength, displacement demands and hysteretic energy dissipation. Furthermore, the paper shows how the analyses that include bond‐slip yield a better correlation with the experimental results with respect to the analyses that assume a perfect bond. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Geology and geochemistry of Jurassic pelagic sediments, Scisti silicei Formation, southern Apennines, Italy     

Paola Di Leo  Enrico Dinelli  Giovanni Mongelli  Marcello Schiattarella 《Sedimentary Geology》2002,150(3-4):229-246

A better understanding of genesis and palaeoenvironmental setting of the Scisti silicei Formation (Lagonegro units, southern Italy) was achieved by means of geochemical analysis integrated with new stratigraphic information. Data show that major and trace element geochemistry of ancient clay-rich beds and banded cherts add new insights into the Mesozoic evolution of the Lagonegro basin. Sedimentary contributions to Jurassic shales sampled during this study were mainly derived from two major sources: (i) a dominant terrigenous fine-grained component, having affinity with average upper continental crust that had not undergone intense weathering and (ii) biogenic siliceous material. The latter component occurs in clay-rich layers from the “basal member” of the Scisti silicei Formation.

Composition varies up section and accounts for changes in the detrital supply due to bathymetric oscillations. The compositional variations from the basal to the overlying member are consistent with a distal source passing in time to a more “proximal” source, as indicated by sharp changes in the concentrations of detrital elements (Ti, Zr and Nb). It is likely that increased detrital input occurred through turbidity current deposition. Finally, the chemical features of the clay-rich layers from the upper cherty portion of the studied succession imply a progressive deepening of the basin.

The lack of any mafic and hydrothermal contributions in the Jurassic shales as well as the continental nature of detrital input suggests that the Lagonegro basin was located between two carbonate platforms, in accordance with the classical restoration of the African–Apulian palaeomargin. Thus, the basin acted as a preferential sink connected to the African cratonic areas through a southern entry point.  相似文献   

Thermal springs,fumaroles and gas vents of continental Yemen: Their relation with active tectonics,regional hydrology and the country’s geothermal potential     

Angelo Minissale  Mohamed A. Mattash  Orlando Vaselli  Franco Tassi  Ismail N. Al-Ganad  Enrico Selmo  Nasr M. Shawki  Dario Tedesco  Robert Poreda  Abdassalam M. Ad-Dukhain  Mohammad K. Hazzae 《Applied Geochemistry》2007

Most thermal springs of continental Yemen (about 65 emergences at 48 sampling sites) and a couple of fumaroles and boiling water pools have been sampled and analyzed for chemical and isotopic composition in the liquid phase and the associated free-gas phase. Whatever the emergence, all the water discharges have an isotopic signature of meteoric origin. Springs seeping out from high altitudes in the central volcanic plateau show a prevalent Na–HCO₃-composition, clearly affected by an anomalous flux of deep CO₂ deriving from active hydrothermal systems located in the Jurassic Amran Group limestone sequence and/or the Cretaceous Tawilah Group, likely underlying the 2000–3000 m thick volcanic suite. At lower elevations, CO₂ also affects the composition of some springs emerging at the borders of the central volcanic plateau.  相似文献   

Numerical simulation of internal boundary-layer development and comparison with atmospheric data     

János Józsa  Barbara Milici  Enrico Napoli 《Boundary-Layer Meteorology》2007,123(1):159-175

A finite-volume numerical model is employed to investigate the adaptation of the atmospheric boundary layer to a change in the underlying surface roughness, such as that existing in the transition from land to the free surface of a water body. Numerical results are validated by comparison with neutral stratification atmospheric data and compared with the internal boundary-layer (IBL) heights computed using a number of existing empirical formulae. The numerical analysis allows an extension of the fetch range in which the existing formulae, calibrated only by comparison with short fetch data, may be applied. An argument is offered that the spatial variability of the water surface roughness should be also taken into account for the IBL development over the surface of a water body.  相似文献   

Temporal Variability of Major and Trace Element Concentrations in the Groundwaters of Mt. Etna (Italy): Effects of Transient Input of Magmatic Fluids Highlighted by Means of Cluster Analysis     

Salvatore Giammanco  Massimo Ottaviani  Enrico Veschetti 《Pure and Applied Geophysics》2007,164(12):2523-2547

Data for major, minor and trace elements in groundwaters from Mt. Etna volcano collected in 1994, 1995 and 1997 were analyzed using Cluster Analysis (CA). Two groups of sampling sites were identified (named clusters A and B), mainly on the basis of their different salinity and content of dissolved CO₂. The highest levels of both of these parameters were observed in the sites of cluster A, located in the lower south-western and central eastern flanks of the volcano. For both of the statistical groups CA was repeated, taking into account the mean values of each parameter in time, and the results allowed us to recognize four distinct groups of parameters for each group of sites on the basis of their temporal patterns. Four different types of temporal patterns were recognized: concave, convex, increasing, decreasing. The observed changes were basically interpreted as a result of the different response of dissolved chemical elements to changes in the aqueous environment and/or in their solubility/mobility in water due to different rates of input of magmatic gases to Etna’s aquifers. The main changes occurred in 1995, when Etna’s volcanic activity resumed after a two-year period of rest. The temporal changes of the majority of the studied parameters (water temperature, water conductivity, Eh, pH, Al, Mg, B, Ca, Cl⁻, Hg, Mn, Mo, Na, Ni, Se, Si, Sr, Cr Zn and pCO₂) were not cluster-dependent, therefore they were not apparently affected by differences in water salinity between the two groups of sampling sites. A limited number of parameters (Ti, K, Li, HCO₃⁻, As, Fe, SO₄²⁻, Cu and V), however, manifested different behaviors, depending on the cluster of sites to which they belonged, thus suggesting their apparent dependency on water salinity.  相似文献   

Dust-enshrouded asymptotic giant branch stars in the solar neighbourhood     

Enrico A. Olivier †  Patricia Whitelock  Fred Marang 《Monthly notices of the Royal Astronomical Society》2001,326(2):490-514

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The influence of wind on measurements of seismic noise   总被引：4，自引：0，他引：4  

Marco Mucciarelli  Maria Rosaria Gallipoli  Domenico Di Giacomo  Francesco Di Nota  Enrico Nino 《Geophysical Journal International》2005,161(2):303-308

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Electron density and temperature measurements, and abundance anomalies in the solar atmosphere     

Anita Mohan  Bhola N. Dwivedi  Enrico Landi 《Journal of Astrophysics and Astronomy》2000,21(3-4):407-411

Using spectra obtained from the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph on the spacecraft SOHO (Solar and Heliospheric Observatory), we investigate the height dependence of electron density, temperature and abundance anomalies in the solar atmosphere. In particular, we present the behaviour of the solar FIP effect (the abundance enhancement of elements with first ionization potential < 10 eV in the corona with respect to photospheric values) with height above an active region observed at the solar limb, with emphasis on the so-called transition region lines.  相似文献   

Turbulence in the Stable Boundary Layer at Higher Richardson Numbers   总被引：1，自引：1，他引：0  

Enrico Ferrero  Lihong Quan  Davide Massone 《Boundary-Layer Meteorology》2011,139(2):225-240

We present some algebraic and numerical simulations of the stable boundary layer. We also discuss the problem of the existence of a critical Richardson number (Ri), beyond which the turbulence is suppressed. We compare the results of a second-order algebraic model with those of a third-order numerical model and, to this purpose, numerical simulations of a wind-tunnel flow, which is characterized by various Richardson numbers, were performed. As far as the second-order model is concerned, solutions, for the Richardson number greater than any critical value, can be obtained by modifying the time scales of the second-order equation pressure correlation terms in order to account for a buoyancy damping factor. We show that using a third-order model allows the same results (no critical Richardson number) to be obtained without modifications to the time scales. It is suggested that the non-locality, accounted for by the third-order moments, could allow the turbulence to persist also for Ri > 1.  相似文献