24,856 research outputs found
Experimental performance and analysis of 15.04-centimeter-tip-diameter, radial-inflow turbine with work factor of 1.126 and thick blading
The aerodynamic design, the performance, and an internal loss breakdown were examined for a 15.04 cm tip diameter, radial-inflow turbine. The design application was to drive a two stage, 10 to 1 pressure ratio compressor with a mass flow of 0.952 kg/sec and a rotative speed of 70,000 rmp. The turbine inlet temperature was 1478 K, and the turbine was designed with blades thick enough for internal cooling passages. The rotor tip diameter was limited to 86 percent of optimum in order to obtain a reduced tip speed design. The turbine was fabricated with solid, uncooled blading and tested in air at nominal inlet pressure and temperature of 1.379 x 10000 N/sq m and 322.2 K, respectively. Results indicated the turbine total efficiency to be 5.3 points less than design. Analysis of these results has indicated the deficit in performance to be due to stator secondary flow losses, vaneless space surface friction losses, and trailing edge wake mixing losses
Relativistic Klein-Gordon-Maxwell multistream model for quantum plasmas
A multistream model for spinless electrons in a relativistic quantum plasma
is introduced by means of a suitable fluid-like version of the
Klein-Gordon-Maxwell system. The one and two-stream cases are treated in
detail. A new linear instability condition for two-stream quantum plasmas is
obtained, generalizing the previously known non-relativistic results. In both
the one and two-stream cases, steady-state solutions reduce the model to a set
of coupled nonlinear ordinary differential equations, which can be numerically
solved, yielding a manifold of nonlinear periodic and soliton structures. The
validity conditions for the applicability of the model are addressed
Broad-line region structure and kinematics in the radio galaxy 3C 120
Broad emission lines originate in the surroundings of supermassive black
holes in the centers of active galactic nuclei (AGN). One method to investigate
the extent, structure, and kinematics of the BLR is to study the continuum and
line profile variability in AGN. We selected the radio-loud Seyfert 1 galaxy 3C
120 as a target for this study. We took spectra with a high signal-to-noise
ratio of 3C 120 with the 9.2m Hobby-Eberly Telescope between Sept. 2008 and
March 2009. In parallel, we photometrically monitored the continuum flux at the
Wise observatory. We analyzed the continuum and line profile variations in
detail (1D and 2D reverberation mapping) and modeled the geometry of the
line-emitting regions based on the line profiles. We show that the BLR in 3C
120 is stratified with respect to the distance of the line-emitting regions
from the center with respect to the line widths (FWHM) of the rms profiles and
with respect to the variability amplitude of the emission lines. The emission
line wings of H{\alpha} and H{\beta} respond much faster than their central
region. This is explained by accretion disk models. In addition, these lines
show a stronger response in the red wings. However, the velocity-delay maps of
the helium lines show a stronger response in the blue wing. Furthermore, the
HeII{\lambda}4686 line responds faster in the blue wing in contradiction to
observations made one and a half years later when the galaxy was in a lower
state. The faster response in the blue wing is an indication for central
outflow motions when this galaxy was in a bright state during our observations.
The vertical BLR structure in 3C 120 coincides with that of other AGN. We
confirm the general trend: the emission lines of narrow line AGN originate at
larger distances from the midplane than AGN with broader emission lines.Comment: 18 pages, 25 figures, Astronomy & Astrophysics in pres
The uniting of Europe and the foundation of EU studies: revisiting the neofunctionalism of Ernst B. Haas
This article suggests that the neofunctionalist theoretical legacy left by Ernst B. Haas is somewhat richer and more prescient than many contemporary discussants allow. The article develops an argument for routine and detailed re-reading of the corpus of neofunctionalist work (and that of Haas in particular), not only to disabuse contemporary students and scholars of the normally static and stylized reading that discussion of the theory provokes, but also to suggest that the conceptual repertoire of neofunctionalism is able to speak directly to current EU studies and comparative regionalism. Neofunctionalism is situated in its social scientific context before the theory's supposed erroneous reliance on the concept of 'spillover' is discussed critically. A case is then made for viewing Haas's neofunctionalism as a dynamic theory that not only corresponded to established social scientific norms, but did so in ways that were consistent with disciplinary openness and pluralism
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