17,796 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
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
Visualization of oxygen distribution patterns caused by coral and algae.
Planar optodes were used to visualize oxygen distribution patterns associated with a coral reef associated green algae (Chaetomorpha sp.) and a hermatypic coral (Favia sp.) separately, as standalone organisms, and placed in close proximity mimicking coral-algal interactions. Oxygen patterns were assessed in light and dark conditions and under varying flow regimes. The images show discrete high oxygen concentration regions above the organisms during lighted periods and low oxygen in the dark. Size and orientation of these areas were dependent on flow regime. For corals and algae in close proximity the 2D optodes show areas of extremely low oxygen concentration at the interaction interfaces under both dark (18.4 ± 7.7 ”mol O2 L(- 1)) and daylight (97.9 ± 27.5 ”mol O2 L(- 1)) conditions. These images present the first two-dimensional visualization of oxygen gradients generated by benthic reef algae and corals under varying flow conditions and provide a 2D depiction of previously observed hypoxic zones at coral algae interfaces. This approach allows for visualization of locally confined, distinctive alterations of oxygen concentrations facilitated by benthic organisms and provides compelling evidence for hypoxic conditions at coral-algae interaction zones
Using the J1-J2 Quantum Spin Chain as an Adiabatic Quantum Data Bus
This paper investigates numerically a phenomenon which can be used to
transport a single q-bit down a J1-J2 Heisenberg spin chain using a quantum
adiabatic process. The motivation for investigating such processes comes from
the idea that this method of transport could potentially be used as a means of
sending data to various parts of a quantum computer made of artificial spins,
and that this method could take advantage of the easily prepared ground state
at the so called Majumdar-Ghosh point. We examine several annealing protocols
for this process and find similar result for all of them. The annealing process
works well up to a critical frustration threshold.Comment: 14 pages, 13 figures (2 added), revisions made to add citations and
additional discussion at request of referee
Kondo temperature of magnetic impurities at surfaces
Based on the experimental observation, that only the close vicinity of a
magnetic impurity at metal surfaces determines its Kondo behaviour, we
introduce a simple model which explains the Kondo temperatures observed for
cobalt adatoms at the (111) and (100) surfaces of Cu, Ag, and Au. Excellent
agreement between the model and scanning tunneling spectroscopy (STS)
experiments is demonstrated. The Kondo temperature is shown to depend on the
occupation of the d-level determined by the hybridization between adatom and
substrate with a minimum around single occupancy.Comment: 4 pages, 2 figure
Light and colour of cirrus, translucent and opaque dust in the high-latitude area of LDN 1642
We have performed a 5-colour surface photometric study of the
high-galactic-latitude area of dark nebula LDN 1642. Scattered light properties
are presented of diffuse, translucent and opaque dust over the range of 3500 --
5500 A. Far infrared absolute photometry at 200 um improves the precision of
and provides a zero point to the extinction. The intensity of the scattered
light depends on dust column density in a characteristic way: for optically
thin dust the intensity first increases linearly, then turns to a saturation
value; at still larger extinctions the intensity turns down to a slow decrease.
The value of the saturated intensity maximum shifts in a systematic way,
from 1.5 mag at 3500 A, to mag at 5500 A. The intensity
curves offer a straight-forward explanation for the behaviour of the
scattered-light colours. At the intensity peak the colour agrees with the
integrated starlight colour, while it is bluer at the low- and redder at the
high-column-density side of the peak, respectively. These colour changes are a
direct consequence of the wavelength dependence of the extinction. We have
compared the colours of the LDN 1642 area with other relevant observational
studies: high-latitude diffuse/translucent clouds, wide-field cirrus dust; and
externally illuminated AGB-star envelopes. For extragalactic
low-surface-brightness sources cirrus is an unwanted foreground contaminant.
Our results for cirrus colours can help to distinguish cases where a diffuse
plume or stream, apparently associated with a galaxy or a group or cluster, is
more likely a local cirrus structure.
Keywords: ISM: dust, extinction -- ISM: clouds, individual LDN 1642 --
Galaxy: solar neighbourhood -- Astronomical instruments, methods and
techniques: methods -- Physical data and processes: scatteringComment: 20 pages, 10 figures, accepted for publication in MNRAS, published as
MNRAS advance article on June 27 202
I would have been/ could be amazing: a social justice oriented visual art rejoinder to whole earth?
The art pieces shown at the conference were informed by current and significant local, national and international contexts, including the continuing so called âmigrant crisisâ and the effects of on-going financial cuts to mental health services (Foley, 2013; Mind, 2014); issues that the art psychotherapists see as points of struggle but that might otherwise be imagined and realised as opportunities, through radical praxis, for sustainable socially just futures.
Summary of participatory content. Each artist provided a reflective piece of writing to accompany their art work included in the exhibition that briefly explained to viewers the thinking and rationale behind the work. Below is a sample of each artistâs contribution with title, media and reflective description of work. Art psychotherapists were available at the exhibition to discuss the art work and motivations behind it with conference participants, which enhanced the contributions of both parties
On the linearization of the generalized Ermakov systems
A linearization procedure is proposed for Ermakov systems with frequency
depending on dynamic variables. The procedure applies to a wide class of
generalized Ermakov systems which are linearizable in a manner similar to that
applicable to usual Ermakov systems. The Kepler--Ermakov systems belong into
this category but others, more generic, systems are also included
Dust reverberation-mapping of the Seyfert 1 galaxy WPVS48
Using robotic telescopes of the Universitatssternwarte Bochum near Cerro
Armazones in Chile, we monitored the z=0.0377 Seyfert 1 galaxy WPVS48 (2MASX
J09594263-3112581) in the optical (B and R) and near-infrared (NIR, J and Ks)
with a cadence of two days. The light curves show unprecedented variability
details. The NIR variation features of WPVS48 are consistent with the
corresponding optical variations, but the features appear sharper in the NIR
than in the optical, suggesting that the optical photons undergo multiple
scatterings. The J and Ks emission, tracing the hot (1600 K) dust echo, lags
the B and R variations by on average 64 +/- 4 days and 71 +/- 5 days,
respectively (restframe). WPVS48 lies on the known tau-M_V relationship.
However, the observed lag is about three times shorter than expected from the
dust sublimation radius r_sub inferred from the optical-UV luminosity, and
explanations for this common discrepancy are searched for. The sharp NIR echos
argue for a face-on torus geometry and allow us to put forward two potential
scenarios: 1) as previously proposed, in the equatorial plane of the accretion
disk the inner region of the torus is flattened and may come closer to the
accretion disk. 2) The dust torus with inner radius r_sub is geometrically and
optically thick, so that the observer only sees the facing rim of the torus
wall, which lies closer to the observer than the torus equatorial plane and
therefore leads to an observed foreshortened lag. Both scenarios are able to
explain the factor three discrepancy between tau and r_sub. Longer-wavelength
dust reverberation data might enable one to distinguish between the scenarios.Comment: 4 pages, 6 figures, Published in Astronomy and Astrophysic
Nuclear alpha-clustering, superdeformation, and molecular resonances
Nuclear alpha-clustering has been the subject of intense study since the
advent of heavy-ion accelerators. Looking back for more than 40 years we are
able today to see the connection between quasimolecular resonances in heavy-ion
collisions and extremely deformed states in light nuclei. For example
superdeformed bands have been recently discovered in light N=Z nuclei such as
Ar, Ca, Cr, and Ni by -ray spectroscopy.
The search for strongly deformed shapes in N=Z nuclei is also the domain of
charged-particle spectroscopy, and our experimental group at IReS Strasbourg
has studied a number of these nuclei with the charged particle multidetector
array {\sc Icare} at the {\sc Vivitron} Tandem facility in a systematical
manner. Recently the search for -decays in Mg has been
undertaken in a range of excitation energies where previously nuclear molecular
resonances were found in C+C collisions. The breakup reaction
MgC has been investigated at E(Mg) = 130 MeV, an
energy which corresponds to the appropriate excitation energy in Mg for
which the C+C resonance could be related to the breakup
resonance. Very exclusive data were collected with the Binary Reaction
Spectrometer in coincidence with {\sc Euroball IV} installed at the {\sc
Vivitron}.Comment: 10 pages, 4 eps figures included. Invited Talk 10th Nuclear Physics
Workshop Marie and Pierre Curie, Kazimierz Dolny Poland, Sep. 24-28, 2003; To
be published in International Journal of Modern Physics
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