95 research outputs found
Detección de delaminaciones y otros defectos de unión en productos de acero multicapa Al/Al-Sn/Al llevando a cabo la monitorización con ondas guiadas EMAT
Rayleigh-Lamb, ultrasonic, guided wave modes were used to detect delamination, embedded steel debris and a brittle intermetallic Al-Fe diffusion bond layer at the interface between clad Al and steel, which were bonded together in a cold roll bonding (CRB) process. Multi-layered samples were produced, with artificially implanted defects of different sizes between the clad Al and steel layer to determine the sensitivity of the guided wave modes to qualitatively indicate the occurrence of defects based on signal attenuation caused by defects. Electromagnetic acoustic transducers (EMATs) were used to generate and detect the guided waves in the pitch and catch technique. Signals were measured in the as rolled and post rolling annealed state to determine the influence of the altered material properties on attenuation and Signal-to-Noise Ratio (SNR). Results show very good sensitivity of the S0 wave mode for delamination and embedded steel debris detection and a relation between attenuation, defect type, size and annealing state. However, detection of the presence of a brittle intermetallic Al-Fe diffusion layer was not possible due to the strong sensitivity to the material properties and thicknesses of the clad Al and steel materials. Micro sections of all samples were examined to explain the observations. The results suggest a promising use of Rayleigh-Lamb guided wave modes for online detection of bond defects in serial production of Al-Sn alloy/steel bimetal strips
Luminous infrared galaxies as possible sources of the UHE cosmic rays
Ultra High Energy (UHE) particles coming from discrete extragalactic sources
are potential candidates for EAS events above a few tens of EeV. In particular,
galaxies with huge infrared luminosity triggered by collision and merging
processes are possible sites of UHECR acceleration. Using the PSCz catalogue of
IR galaxies we calculate a large scale anisotropy of UHE protons originating in
the population of the luminous infrared galaxies (LIRGs). Small angle particle
scattering in weak irregular extragalactic magnetic fields as well as
deflection by regular Galactic field are taken into account. We give analytical
formulae for deflection angles with included energy losses on cosmic microwave
background (CMB). The hypotheses of the anisotropic and isotropic distributions
of the experimental data above 40 EeV from AGASA are checked, using various
statistical tests. We show that on the basis of the small scale clustering
analysis there is a much better correlation of the UHECRs data below GZK
cut-off with the predictions of the LIRG origin than with those of isotropy. We
derive analytical formulae for a probability of a given number of doublets,
triplets and quadruplets for any density distribution of independent events on
the sky. The famous AGASA UHE triple event is found to be very well correlated
on the sky with the brightest extragalactic infrared source within 70 Mpc -
merger galaxies Arp 299 (NGC 3690 + IC 694).Comment: 17 pages, 10 figures, accepted for publ: Journal of Physics
Experimental results on strangeness production in proton-proton collisions at COSY
The production of K+ and K- mesons in elementary proton-proton collision has
been investigated at the Cooler Synchrotron COSY in Juelich. A high quality
proton beam with low emittance and small momentum spread permitted to study the
creation of these mesons very close to the kinematical threshold. The energy
dependence of the total cross section is investigated using internal beam
facilities providing a high accuracy particle momentum determination as well as
an external non-magnetic detection setup with a large geometrical acceptance.
The determination of the four-momentum vectors for all ejectiles of each
registered event gives the complete kinematical information allowing to study
the interaction of the outgoing particles. Results on the performed studies of
the pp --> pp K+ K-, pp --> p Lambda K+ and pp --> p Sigma0 K+ reactions will
be presented and their relevance to the interpretation of heavy ion collisions
will be discussed.Comment: 8 pages, 6 figures, plenary talk at 6th International Conference On
Strange Quarks in Matter: '2001 - A Flavorspace Odyssey' (SQM2001),
Frankfurt, Germany, September 25-29, 2001, to be published in J. Phys. G:
Nucl. Part. Phy
Reconstruction of inclined air showers detected with the Pierre Auger Observatory
We describe the method devised to reconstruct inclined cosmic-ray air showers
with zenith angles greater than detected with the surface array of
the Pierre Auger Observatory. The measured signals at the ground level are
fitted to muon density distributions predicted with atmospheric cascade models
to obtain the relative shower size as an overall normalization parameter. The
method is evaluated using simulated showers to test its performance. The energy
of the cosmic rays is calibrated using a sub-sample of events reconstructed
with both the fluorescence and surface array techniques. The reconstruction
method described here provides the basis of complementary analyses including an
independent measurement of the energy spectrum of ultra-high energy cosmic rays
using very inclined events collected by the Pierre Auger Observatory.Comment: 27 pages, 19 figures, accepted for publication in Journal of
Cosmology and Astroparticle Physics (JCAP
The Pierre Auger Observatory III: Other Astrophysical Observations
Astrophysical observations of ultra-high-energy cosmic rays with the Pierre
Auger ObservatoryComment: Contributions to the 32nd International Cosmic Ray Conference,
Beijing, China, August 201
Entanglement of positive definite functions on compact groups
We define and study entanglement of continuous positive definite functions on
products of compact groups. We formulate and prove an infinite-dimensional
analog of Horodecki Theorem, giving a necessary and sufficient criterion for
separability of such functions. The resulting characterisation is given in
terms of mappings of the space of continuous functions, preserving positive
definiteness. The relation between the developed group-theoretical formalism
and the conventional one, given in terms of density matrices, is established
through the non-commutative Fourier analysis.Comment: published versio
Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory
7
The Pierre Auger Observatory II: Studies of Cosmic Ray Composition and Hadronic Interaction models
Studies of the composition of the highest energy cosmic rays with the Pierre
Auger Observatory, including examination of hadronic physics effects on the
structure of extensive air showers.Comment: Contributions to the 32nd International Cosmic Ray Conference,
Beijing, China, August 201
The Pierre Auger Observatory IV: Operation and Monitoring
Technical reports on operations and monitoring of the Pierre Auger
ObservatoryComment: Constributions to 32nd International Cosmic Ray Conference, Beijing,
China, August 201
Noncomparabilities & Non Standard Logics
Many normative theories set forth in the welfare economics, distributive justice and cognate literatures posit noncomparabilities or incommensurabilities between magnitudes of various kinds. In some cases these gaps are predicated on metaphysical claims, in others upon epistemic claims, and in still others upon political-moral claims. I show that in all such cases they are best given formal expression in nonstandard logics that reject bivalence, excluded middle, or both. I do so by reference to an illustrative case study: a contradiction known to beset John Rawls\u27s selection and characterization of primary goods as the proper distribuendum in any distributively just society. The contradiction is avoided only by reformulating Rawls\u27s claims in a nonstandard form, which form happens also to cohere quite attractively with Rawls\u27s intuitive argumentation on behalf of his claims
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