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261.
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Horacio A. Dottori 《Astrophysics and Space Science》1980,67(2):417-426
Photographic spectrophotometry andUBV multi-aperture photometry are used to analyze the stellar composition and gas content within a region of 12 arcsec in the nuclear bulk of the Sérsic-Pastoriza galaxy NGC 5236. An internal reddeningE(B–V)=0.2±0.1 mag. is derived for this region. A fail of the fit between the synthetic and the observed continuum for 5600Å6500 Å is discussed. 相似文献
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Oscar M?ller Ricardo O.Foschi Juan P.Ascheri Marcelo Rubinstein Sergio Grossman 《地震工程与工程振动(英文版)》2015,14(2):315-328
Performance-based design in earthquake engineering is a structural optimization problem that has, as the objective, the determination of design parameters for the minimization of total costs, while at the same time satisfying minimum reliability levels for the specifi ed performance criteria. Total costs include those for construction and structural damage repairs, those associated with non-structural components and the social costs of economic losses, injuries and fatalities. This paper presents a general framework to approach this problem, using a numerical optimization strategy and incorporating the use of neural networks for the evaluation of dynamic responses and the reliability levels achieved for a given set of design parameters. The strategy is applied to an example of a three-story offi ce building. The results show the importance of considering the social costs, and the optimum failure probabilities when minimum reliability constraints are not taken into account. 相似文献
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This study reports the performance of a combined anaerobic–aerobic packed‐bed reactor that can be used to treat domestic sewage. Initially, a bench‐scale reactor was operated in three experimental phases. In the first phase, the anaerobic reactor was operated with an average organic matter removal efficiency of 77% for a hydraulic retention time (HRT) of 10 h. In the second phase, the reactor was operated with an anaerobic stage followed by an aerobic zone, resulting in a mean value of 91% efficiency. In the third and final phase, the anaerobic–aerobic reactor was operated with recirculation of the effluent of the reactor through the anaerobic zone. The system yielded mean total nitrogen removal percentages of 65 and 75% for recycle ratios (r) of 0.5 and 1.5, respectively, and the chemical oxygen demand (COD) removal efficiencies were higher than 90%. When the pilot‐scale reactor was operated with an HRT of 12 h and r values of 1.5 and 3.0, its performance was similar to that observed in the bench‐scale unit (92% COD removal for r = 3.0). However, the nitrogen removal was lower (55% N removal for r = 3.0) due to problems with the hydrodynamics in the aerobic zone. The anaerobic–aerobic fixed‐bed reactor with recirculation of the liquid phase allows for concomitant carbon and nitrogen removal without adding an exogenous source of electron donors and without requiring any additional alkalinity supplementation. 相似文献
269.
Marcelo J. S. De Lemos 《Acta Geophysica》2008,56(3):562-583
The ability to realistically model flows through heterogeneous domains, which contain both solid and fluid phases, can benefit
the analysis and simulation of complex real-world systems. Environmental impact studies, as well as engineering equipment
design, can both take advantage of reliable modelling of turbulent flow in permeable media. Turbulence models proposed for
such flows depend on the order of application of volume-and time-average operators. Two methodologies, following the two orders
of integration, lead to distinct governing equations for the statistical quantities. This paper reviews recently published
methodologies to mathematically characterize turbulent transport in permeable media.
A new concept, called double-decomposition, is here discussed and instantaneous local transport equations are reviewed for
clear flow before the time and volume averaging procedures are applied to them. Equations for turbulent transport follow,
including their detailed derivation and a proposed model for suitable numerical simulations. The case of a moving porous bed
is also discussed and transport equations for the mean and turbulent flow fields are presented. 相似文献
270.
Seismic response of nonstructural components in case of nonlinear structures based on floor response spectra method 总被引:1,自引:0,他引:1
Marcelo Oropeza Pascale Favez Pierino Lestuzzi 《Bulletin of Earthquake Engineering》2010,8(2):387-400
This paper investigates the response of nonstructural components in the presence of nonlinear behavior of the primary structure
using floor response spectra method (FRS). The effect of several parameters such as initial natural frequency of the primary
structure, natural frequency of the nonstructural components (subsystem), strength reduction factor and hysteretic model have
been studied. A database of 164 registered ground acceleration time histories from the European Strong-Motion Database is
used. Results are presented in terms of amplification factor and resonance factor. Amplification factor quantifies the effect
of inelastic deformations of the primary structure on subsystem response. Resonance factor quantifies the variation of the
subsystem response considering the primary structure acceleration. Obtained results differed from precedent studies, particularly
for higher primary structure periods. Values of amplification factor are improved. Obtained results of resonance factor highlight
an underestimation of peak values according to current design codes such as Eurocode 8. Therefore a new formulation is proposed. 相似文献