8,650 research outputs found
Theoretical prediction and spectroscopic fingerprints of an orbital transition in CeCu2Si2
We show that the heavy-fermion compound CeCu2Si2 undergoes a transition
between two regimes dominated by different crystal-field states. At low
pressure P and low temperature T the Ce 4f electron resides in the atomic
crystal-field ground state, while at high P or T the electron occupancy and
spectral weight is transferred to an excited crystal-field level that
hybridizes more strongly with itinerant states. These findings result from
first-principles dynamical-mean-field-theory calculations. We predict
experimental signatures of this orbital transition in X-ray spectroscopy. The
corresponding fluctuations may be responsible for the second high-pressure
superconducting dome observed in this and similar materials.Comment: 5 pages, 4 figures + 5 supplementary page
Il DM 93/2017 sui controlli degli strumenti di metrologia legale
Questo articolo analizza il recente Decreto Ministeriale che disciplina le
verifiche periodiche sugli strumenti di misura impiegati in metrologia legale.
Vengono discussi gli aspetti giuridici e metrologici, e si mostra come la
palese mancanza di competenze metrologiche con cui sono stati redatti gli
allegati tecnici rischi seriamente di compromettere e vanificare tutto ciĂČ che
di buono Ăš stato introdotto, dal punto di vista specificatamente giuridico, in
questo delicato settore
Conformal Antenna Array for Millimeter-Wave Communications: Performance Evaluation
In this paper, we study the influence of the radius of a cylindrical
supporting structure on radiation properties of a conformal millimeter-wave
antenna array. Bent antenna array structures on cylindrical surfaces may have
important applications in future mobile devices. Small radii may be needed if
the antenna is printed on the edges of mobile devices and in items which human
beings are wearing, such as wrist watches, bracelets and rings. The antenna
under study consists of four linear series-fed arrays of four patch elements
and is operating at 58.8 GHz with linear polarization. The antenna array is
fabricated on polytetrafluoroethylene substrate with thickness of 0.127 mm due
to its good plasticity properties and low losses. Results for both planar and
conformal antenna arrays show rather good agreement between simulation and
measurements. The results show that conformal antenna structures allow
achieving large angular coverage and may allow beam-steering implementations if
switches are used to select between different arrays around a cylindrical
supporting structure.Comment: Keywords: conformal antenna, millimeter-wave communications, patch
antenna array. 11 pages, 10 figures, 1 tabl
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