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71.
Ugo Chiocchini Fabio Castaldi Maurizio Barbieri Valeria Eulilli 《Hydrogeology Journal》2011,19(4):949-952
72.
Maurizio Ternullo 《Solar physics》1987,112(1):153-163
An analysis of Ca ii spectroheliograms obtained at Catania Astrophysical Observatory throughout the years 1967–1977 has been carried out, to throw light on the complex relationship linking (Ternullo, 1986) the angular rotation rate of Ca plages with their age, as well as with solar cycle phase, and with latitude. Given the rotation law w =, a + b sin2
I, solar-cycle-related oscillatory properties both of a and b coefficients are described, both for young and old Ca plages.The aging-dependent rate-increments vary, for each epoch, both in module and sign with latitude; that results in deep distortions of the differential rotation latitudinal profile, which exhibits, when old plages are taken into account, a fine structure (Ternullo, 1987). Such a fine structure is absent in the young plage differential rotation profile.Throughout the time interval under examination, the torsional waves observed by Howard and LaBonte (1980) have appeared to be in close spatial relationship with the latitude bands where aging-dependent rate increments occur.
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73.
The transfer equations for the Stokes parameters in the presence of magnetic field and under the hypothesis of LTE are derived in an original way by the use of density matrix techniques.The results are substantially the same as those previously obtained by other authors. We finally compare our results to the previous ones in order to clarify some discrepancies still present in the literature. 相似文献
74.
75.
Vibration isolation is well recognized as an effective mitigation strategy for acceleration‐sensitive equipment subjected to earthquake. In the present paper, an equipment isolation system with nonlinear hysteretic behaviour is proposed and a methodology for the optimal design is developed. An integrable constitutive model, derived from the mathematical Duhem hysteresis operator, is adopted for the isolation system. The optimization procedure is defined through a dual‐criteria approach that involves a transmissibility criterion combined with an energy performance criterion: the former consists in limiting the absolute acceleration of the isolated equipment below an allowable threshold value; the latter, in maximizing the ratio between the energy dissipation due to hysteresis and the input energy to reduce the isolator displacements. The seismic effectiveness of the nonlinear hysteretic isolation system is numerically investigated under natural accelerograms with different frequency content and increasing levels of excitation. Both ground‐mounted and floor‐mounted equipment items are considered in the analyses; in the second case, the dynamic interaction between the equipment and its supporting structure is taken into account in the design of the isolation system, and its effects on the isolation performance and the structural response are discussed. Comparisons in terms of effectiveness and robustness with a linear isolation system with viscoelastic behaviour are eventually provided. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
76.
Maurizio M. D’Eliseo 《Astrophysics and Space Science》2011,332(1):121-128
We study the general relativistic orbital equation and using a straightforward perturbation method and a mathematical device
first introduced by d’Alembert, we work out approximate expressions of a bound planetary orbit in the form of trigonometrical
polynomials and the first three terms of the power series development of the perihelion advance. The results are applied to
a more precise determination of the total mass of the double pulsar J0737-3039. 相似文献
77.
Piero Colajanni Marinella Fossetti Maurizio Papia 《Bulletin of Earthquake Engineering》2013,11(6):2055-2078
This paper presents closed form expressions linking the ultimate bearing capacity to the ultimate curvature of rectangular RC sections subjected to axial load and bending moment acting in one of the two symmetry planes of the section. With respect to possible simplified formulations the following effects are also considered: confinement of the concrete, hardening of the longitudinal reinforcement, and presence of reinforcing bars distributed orthogonally to the neutral axis. The formulation is proposed in dimensional terms after a preliminary definition of the geometrical and mechanical parameters governing the structural response of the class of sections considered. The analytical expressions derived using the proposed approach also allow one to determine the compression level that makes the ultimate bending moment maximum as well as to evaluate the curvature corresponding to the first yielding of the principal reinforcement in tension. Comparing this value of curvature with the ultimate one, an approximate estimation of the available ductility of curvature of the section can be made. The analytical procedure is validated by comparing the results with those obtained using a typical numerical approach. Some experimental results are also considered. 相似文献
78.
Luca Salvati Vittorio Gargiulo Morelli Kostas Rontos Alberto Sabbi 《Urban geography》2013,34(3):376-394
This paper quantifies the extent of exurban development in Mediterranean Europe. The assessment was carried out by studying changes in the urban-to-rural population density gradient between the years 1950 and 2010. Three of the six urban regions in this study have experienced population growth and moderate urban concentration, while two regions appear to be shifting toward population decline and urban de-concentration after having experienced compact expansion. A phase of recent re-urbanization has been observed in one region. Altogether, these findings indicate a common path of urban expansion among representative Mediterranean regions between 1950 and 1980 while, in the following period, the cities experienced distinct development phases. From this study, we conclude that exurban development is mainly the product of a shift from compact and dense to semi-compact and intermediate-density settlements. [Key words: semi-dense urban growth, density-distance curve, Mediterranean Europe]. 相似文献
79.
In this paper, we study the relationship between atmospheric parameters (i.e., temperature and humidity) and radon data. We use the linear Granger causality in order to observe possible connections, on short and mid time scale periods, between radon time series and meteorological parameters that strongly influence radon emissions. The analysis suggests radon emission is not affected by these atmospheric parameters on short periods, while there is an evidence of Granger causality on mid periods. 相似文献
80.
Lo?c Vanderkluysen Andrew J. L. Harris Karim Kelfoun Costanza Bonadonna Maurizio Ripepe 《Bulletin of Volcanology》2012,74(8):1849-1858
We collected thermal infrared video of two explosive eruptions at Stromboli in June 2008 and manually traced the trajectories of 95 particles launched during two eruptions. We found that 10–15?% of the analyzed trajectories deviated from predicted curves due to collisions, causing one particle to travel horizontally more than twice as far as expected. Furthermore, we observed an oscillatory cooling behavior for the airborne pyroclasts, with a median period of 0.46?s. Measured cooling was typically much faster than model-predicted cooling with discrepancies of up to 40?% between measured cooling and theoretical modeling. We interpret the measured cooling curves as resulting from the spinning and twisting and tearing of particles during travel: the periodic re-exposing of the hotter core of the pyroclasts to the atmosphere may cause the observed oscillations, and the spinning may accelerate cooling by enhancing convective heat transfer. Current volcanic trajectory and cooling models do not account for projectile collisions, spinning, or tearing and can thus severely underestimate the maximum landing distance and cooling rates of large pyroclasts. 相似文献