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

Optical phase-locked loop for coherent detection optical receiver

Lette

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

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 ciò che di buono è stato introdotto, dal punto di vista specificatamente giuridico, in questo delicato settore