Power consumption evaluation of circuit-switched versus packet-switched optical backbone networks

While telecommunication networks have historically been dominated by a circuit-switched paradigm, the last decades have seen a clear trend towards packet-switched networks. In this paper we evaluate how both paradigms perform in optical backbone networks from a power consumption point of view, and whether the general agreement of circuit switching being more power-efficient holds. We consider artificially generated topologies of various sizes, mesh degrees and not yet previously explored in this context transport linerates. We cross-validate our findings with a number of realistic topologies. Our results show that, as a generalization, packet switching can become preferable when the traffic demands are lower than half the transport linerate. We find that an increase in the network node count does not consistently increase the energy savings of circuit switching over packet switching, but is heavily influenced by the mesh degree and (to a minor extent) by the average link length

Pliocene crustal shortening on the Tyrrhenian side of the northern Apennines: evidence from the Gavorrano antiform (southern Tuscany, Italy)

The northern Tyrrhenian Sea and the inner northern Apennines are classically regarded as a late Miocene–Pleistocene back-arc system developed as a consequence of slab rollback along active subduction zones. We present new geological and structural data on the Gavorrano antiform, a key sector of the inner northern Apennines. Lying close to the northern Tyrrhenian Sea, it provides clear evidence of Pliocene shortening deformation and magma emplacement. The orientation of 1 (N50°E–N80°E) derived by fault slip data inversion is consistent with a general ENE–WSW shortening direction. Furthermore, this ENE–WSW-trending orientation of 1 is compatible with the compressive deformation recorded in coeval sedimentary basins. On this basis we suggest that the inner northern Apennines were affected by crustal shortening during the Pliocene. This scenario matches well geophysical data suggesting that since the Late Messinian (6–5 Ma) subduction rollback and back-arc extension strongly decreased in the northern Tyrrhenian Sea, whereas they continued as active processes in the southern Tyrrhenian Sea

Performance assessment of pulse blanking mitigation in presence of multiple Distance Measuring Equipment/Tactical Air Navigation interference on Global Navigation Satellite Systems signals

It is known that the Aeronautical Radio Navigation Systems sharing the Global Navigation Satellite Systems (GNSS) frequency band represent a threat to the satellite-based navigation services. Distance Measuring Equipment (DME) and Tactical Air Navigation (TACAN) systems broadcast strong pulsed ranging signals within the Global Positioning System L5 and Galileo E5a frequency bands where the aviation positioning aids services are allocated. This study provides an experimental assessment of the DME/TACAN interference effect on the GNSS receivers performance in scenarios where the presence of several transmitters in view generates radio-frequency interference hard to mitigate by means of the classical solutions. In detail, analysis in terms of the receiver performance will be presented by showing the effect of the non-ideal pulse blanking on the GNSS signal quality. The optimal set-up of the mitigation process, investigated by means of a software simulation, is provided

Dead Time Management in GaN Based Three-Phase Motor Drives

This paper deals with the dead time selection in Gallium Nitride (GaN) FET based three-phase brushless DC motor drives. The GaN wide-bandgap (WBG) technology enables the increase of the switching frequency compared with silicon MOSFET. In inverter applications, it is necessary to insert a dead time in the switching signals, to avoid cross conduction in the inverter leg. The dead time selection is a compromise between the switching time and the quality of the inverter output waveforms. GaN FETs can operate with dead times in the range of tens of ns. In this paper the advantages of the GaN technology in the reduction of dead time in terms of output waveforms distortion and speed ripple compared with silicon MOSFET are carried out. Furthermore, an evaluation on the dead time compensation technique compared with the hardware technology reduction is investigated demonstrating the effectiveness and the saving of software and hardware resources obtained by GaN FET devices

Monolithic Bidirectional Switch Based on GaN Gate Injection Transistors

The paper deals with a bi-directional switch based on N-channel enhancement-mode GaN FET. The proposed device is a Gate Injection Transistor monolithic solution to reduce the volume of the switch with high current density and blocking voltage of 600V. It features a dual-gate control pin and two power terminal. In the paper, the main characteristics of the bi-directional switch and the performance in the four-quadrant of operation are examined and discussed. The device characteristics are compared with the traditional MOSFET and IGBT solutions. The gate driver design issues are considered to optimize the switching transient of the GaN-based switch. Finally, an experimental evaluation of the GaN FET as the bidirectional circuit breaker is carried out in an AC power supply system to validate the effectiveness of the proposed monolithic new device

Pliocene crustal shorthening on the Tyrrhenian side of the northern Apennones: evidence from the Gavorrano antiform (southern Tuscany, Italy)

The northern Tyrrhenian Sea and the inner northern Apennines are classically regarded as a late Miocene-Pleistocene back-arc system developed as a consequence of slab roll-back along active subduction zones. We present new geological and structural data on the Gavorrano antiform, a key sector of the inner northern Apennines. Lying close to the northern Tyrrhenian Sea, it provides clear evidence of Pliocene shortening deformation and magma emplacement. The orientation of σ1 (N50°E - N80°E) derived by fault slip data inversion is consistent with a general ENE –WSW shortening direction. Furthermore, this ENE-trending orientation of σ1 is compatible with the compressive deformation recorded in coeval sedimentary basins. On this basis we suggest that the inner northern Apennines were affected by crustal shortening during the Pliocene. This scenario matches well geophysical data suggesting that since the Late Messinian (6 – 5 Ma) subduction rollback and back-arc extension strongly decreased in the northern Tyrrhenian Sea, while they continued as active processes in the southern Tyrrhenian Sea

Geomorphological and geochemical characterization of the 11 August 2008 mud volcano eruption at S. Barbara village (Sicily, Italy) and its possible relationship with seismic activity

On 11 August 2008 a paroxysmal eruption occurred at Santa Barbara mud volcano (MV), located close to Caltanissetta, one of the most densely populated cities of Sicily (Italy). An associated minor event took place on August 2009. Both the events caused severe damage to civil infrastructures located within a range of about 2 km from the eruptive vent. Geomorphological, geochemical, and seismological investigations were carried out for framing the events in the appropriate geodynamic context. Geomorphological surveys recognized, in the immediate surrounding of the main emission point, two different families of processes and landforms: (i) ground deformations and (ii) changes in morphology and number of the fluid emitting vents. These processes were associated to a wider network of fractures, seemingly generated by the shock wave produced by the gas blast that occurred at the main paroxysm. Geochemical characterization allowed an estimation of the source of the fluids, or at least their last standing, at about 3 km depth. Finally, the close time relationships observed between anomalous increments of seismic activity and the two main paroxysmal events accounted for a possible common trigger for both the phenomena, even with different timing due to the very different initial conditions and characteristics of the two processes, i.e. seismogenesis and gas overloading