Porous GaP layers prepared by electrochemical anodization of (100)-oriented bulk material was found to exhibit blue and ultraviolet photoluminescence when excited by a KrF excimer laser. The energy position of the UV luminescence band (3.3 eV at 300 K) is explained on the basis of charge carrier confinement in crystalline quantum wires of about 25 Å in diameter. Additional evidence for quantum size effect in porous GaP was obtained by Raman scattering measurements.
Photoconductivity, quenching, thermally stimulated current and decay characteristics are studied in ZnIn2S4 single crystals. Evidence is obtained for the presence of three impurity levels taking part in the photoconductivity process. Optical quenching is attributed to a sensitization centre, which acts as a competitive recombination level. An exponential distribution of electron traps is revealed both by pulsed photoconductivity and by thermocurrent analysis. The two experimental techniques accordingly provide the value of 70 meV/decade for the trap distribution. Some aspects of the nature of the impurity centres are examined.
An optimal energy storage system (ESS) management procedure devoted to full renewable energy sources (RESs) exploitation is presented in this paper. It consists of an appropriate scheduling procedure and a real-time control strategy, which both aim to increase the RES penetration level as much as possible. In particular, the one-day-ahead scheduling procedure synthesizes the combined RES-ESS energy production profile with the aim of minimizing the RES energy production curtailments by means of ESS energy buffering. The real-time control strategy is developed in order to track the scheduled profile as well as possible by mitigating forecasting errors, thus improving RES reliability. The worth and effectiveness of the proposed management procedure is verified through a wide simulation study, which is carried out by means of the Matlab software package
A novel online discrete-time parameters identification algorithm suitable for surface-mounted permanent magnet synchronous machines (SPMs) is presented in this paper. It is developed by means of the Model Reference Adaptive System (MRAS) technique and the Popov Hyperstability Criterion in order to identify SPM discrete-time model parameters. In particular, good accuracy of discrete-time parameters is required by digital control systems, especially by predictive control algorithms, which present a low robustness against parameters mismatches. Hence, an extensive simulation study is firstly carried out in the Matlab Simulink environment with the aim of testing the effectiveness and robustness of the proposed identification algorithm against inverter un-idealities. Then, the proposed identification procedure is experimentally validated on a predictive controlled radial-flux SPM, driven by a Field Programmable Gate Arrays (FPGA) control board
Electric power systems are experiencing relevant changes involving the growing penetration of distributed generation and energy storage systems, the introduction of electric vehicles, the management of responsive loads, the proposals for new energy markets and so on. Such an evolution is pushing a paradigm shift that is one of the most important challenges in power network design: the management must move from traditional planning and manual intervention to full “smartization” of medium and low voltage networks. Peculiarities and criticalities of future power distribution networks originate from the complexity of the system which includes both the physical aspects of electric networks and the cyber aspects, like data elaboration, feature extraction, communication, supervision and control; only fully integrated advanced monitoring systems can foster this transition towards network automation. The design and development of such future networks require distinct kinds of expertise in the industrial and information engineering fields. In this context, this paper provides a comprehensive review of current challenges and multidisciplinary interactions in the development of smart distribution networks. The aim of this paper is to discuss, in an integrated and organized manner, the state of the art while focusing on the need for interaction between different disciplines and highlighting how innovative and future-proof outcomes of both research and practice can only emerge from a coordinated design of all the layers in the smart distribution network architecture.
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