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Distinguishing short circuit and normal operation currents in DC urban light railway systems
No full textDC urban light railway systems are used as public transportation systems in many towns worldwide. In these systems, short circuit currents are often similar, both in steady state magnitude and in rate-of-rise, to normal operation currents. In order to properly set the protection relays, to obtain short circuit discrimination and to avoid nuisance trippings, it is important to analyse short circuit and normal operation current patterns. This paper presents the results of measurement campaigns performed for this purpose on the tram network of Turin, in Northern Italy
Application of a Passive Control Technique to the ISWEC
No full textThe ISWEC is a floating, slack-moored, gyroscopic Wave Energy Converter. The system consists of a floating hull carrying a gyroscope inside. The full-scale prototype installed in Pantelleria in 2015 has an electric-mechanical PTO composed by a gearbox and a brushless torque motor. The system is torque controlled to keep the gyroscope in the desired position range and to obtain maximum productivity. At present, the proportional-derivative (PD) law regulating the torque on the PTO includes a stiffness term to recall the gyroscope in the vertical position and a damping term to extract power. The PTO performs the recall effect, resulting in an increase of the root-mean-squared torque load and inducing a flux of reactive power not directly involved in the power extraction. To overcome such problems, this paper analyses the use of an eccentric mass to provide the stiffness term. In order to optimize the power extraction, the recall stiffness and therefore the mass quantity and distance with respect to the precession axis have to be designed. A mass with a variable distance from the precession axis and another one with a fixed position are tested to evaluate if a stiffness term tunable with respect to different sea states carries a relevant gain in system productivity. Numerical simulations with the time domain, non-linear ISWEC model demonstrate a high reduction of the PTO torque levels. Annual productivity and PTO torque in relation to different flywheel speeds are compared for the two different control solutions
Fog Computing and Networking: Part 2
No full textThe articles in this special section focus on the deployment of fog computing in communication networks
A prototype of pixel readout ASIC in 65 nm CMOS technology for extreme hit rate detectors at HL-LHC
No full textSignal Structure-Based Authentication for Civil GNSSs: Recent Solutions and Perspectives
No full textA key aspect to be considered in the design of new generations of global navigation satellite system (GNSS) signals and receivers is a proper partition between system and receiver contribution to the robustness against spoofing attacks. This article maps the current threats and vulnerabilities of GNSS receivers and presents a survey of recent defenses, focusing on cryptographic solutions suitable to authenticate civil signals. Future perspectives and trends are analyzed, with particular emphasis on spreading code authentication techniques, considered as a key innovation for the next generation of civil GNSS signals. An assessment of the robustness and feasibility of the various presented solutions is also provided, analyzing in particular the impact on both current and future receivers
