Search results for "TTR"
showing 10 items of 3945 documents
Simplified Hybrid PD Model in Voids
2011
In this paper a novel approach to model partial discharges (PD) activity taking place inside a spherical void in epoxy resin system has been traced. The approach is based on a time varying conductance of the inner void, subjected to multistress conditions: voltage, temperature and pressure. A simple lumped circuit macro-model simulates the global effects of PD activity: the different parameters influencing the discharge phenomenon in the void are taking into account by using a physical approach resulting in a time varying conductance inside the circuit. The evaluated PD activity has been compared with experimental and simulated one for the accessible and inaccessible part of the system. A d…
Interpretation of PEA Output Signal in a Multilayer Specimen
2018
The aim of the present work is to evaluate the acoustic waves behavior within the Pulsed Electro-Acoustic (PEA) cell, in case of a multilayer specimen, in order to avoid misinterpretation of the output signal. Due to the reflection phenomenon of the acoustic waves travelling within the PEA cell, the output signal could be distorted. Because this aspect, for a given PEA cell with certain ground electrode and absorber thicknesses, depends on the sound velocity and thickness of the specimen under test, the latter must be carefully sized. For this aim, some useful relationships, that must be taken into account are given and described. In particular, a three layers sample simulating an air void …
Simplified hybrid PD model in voids: Pattern validation
2013
The purpose of the present work is to show the validation of a new model to simulate the physical phenomenon of partial discharge (PD) produced in air voids inside insulating epoxy resin. The model has been developed on the basis of a new approach that combines the known circuit model of three capacitors with a model used to describe the behavior of the ionized channel inside of the inclusion during the discharge phenomenon, short-circuiting the capacity that represents the void. The approach is based on time-variable conductance of the void, subjected to multistress conditions: voltage, temperature and pressure. The new approach has been developed from a time variable conductivity model us…
Bach fra le stelle
2014
Il testo costituisce la postfazione del volume di Ramin Bahrami "Il suono dell'Occidente. Le opere musicali che hanno fatto la nostra civiltà" (Mondadori 2014) e prende le mosse dal concetto di "Enciclopedia" per tracciare una riflessione storico-musicologica sulle 14 composizioni che Ramin Bahrami ssume quali imprescindibili punti di riferimento per una visione d'insieme della cultura musicale occidentale: da Monteverdi fino a Schoenberg, passando per Vivaldi, Bach, Wagner, Verdi, Mahler, Rakhmaninov e Stravnsky.
Warm white LED light by frequency down-conversion of mixed yellow and red Lumogen®
2013
This work reports on the benefits and promising opportunities offered by white LED hybrid technology, based on a mixing perylene-based dyes in order to obtain a warm white light for frequency-down conversion. In a standard Ce:YAG-based white LED, the white light appears cold due to the weakness of red wavelength components in the emission spectrum. In order to obtain a warmer white, one possible solution is to add a red phosphor to the yellow one to move the chromatic coordinates properly, though the luminous efficiency drastically decreases due to the increased light absorption of the coating layer. It is generally believed that the low efficiency of warm white LEDs is the main issue today…
Recognition of water masses according to geochemical signatures in the Central Mediterranean sea: Y/Ho ratio and rare earth element behaviour
2007
This study reports the results of geochemical investigations carried out in the Strait of Sicily (Central Mediterranean Sea) during the oceanographic cruise BANSIC 2000, focusing on the area around the Pantelleria Island. We evaluate the interface processes between dissolved phase and suspended particulate matter in the water columns on the basis of Y/Ho ratio and rare earth elements and yttrium distributions that are suitable to trace the occurrence of different water layers in Central Mediterranean Area. The main source of trace elements to the sea water system was recognized in the atmospheric fallout, while different scavenging mechanisms among Y and rare earth elements occur. Cation ex…
Design, modeling, and simulation of a photovoltaic water pumping system
2018
Electric pumps cannot be fed in those areas where they are not connected to the electric public distribution grid. In those areas, it is useful to feed electric pumps by means of the electricity generated from renewable energy sources plants. Among these, the Solar Water Pumping Systems feed electric pump thanks to the electricity generated by a photovoltaic plant. In this paper, a whole SWPS is fully designed, modelled, and simulated in Matlab environment. The proposed implementation is an useful tool for SWPS testing.
A Permanent Magnet Linear Generator for the Enhancement of the Reliability of a Wave Energy Conversion System
2019
In this paper, a linear generator for a highly reliable Wave Energy Conversion system is designed and tested. In order to store energy, the system is able to produce hydrogen The Wave Energy Conversion System consists of an electrical linear generator, a power conversion system and a sea-water electrolyzer. A small scale prototype of the system has been designed and built. The design is oriented to the enhancement of the system robustness and reliability and a Failure Mode and Effects and Criticality Analysis (FMECA) has been used. In order to guarantee an easy extension of the power capability of the marine plant, a modular architecture of the system has been adopted. The design strategy i…
A Preliminary Energy Assessment to Improve the Energy Sustainability in the Small Islands of the Mediterranean Sea
2020
Power plants supplied by renewable energy sources are expanding around the world, in order to reduce the carbon dioxide emissions, limit the global warming and improve the energy sustainability. Despite the relevant achieved results, small islands are heavily reliant on fossil fuels. In this context, renewable energy sources are available but practically unused, due to landscape and economic constraints. This condition is quite common in the Mediterranean Sea. These islands are normally fed by a stand-alone electrical grid and a power plant, equipped with diesel engines. In order to improve the sustainability of the energy sector, the paper considers the case study of Ustica, a small Italia…
Guidelines proposal for a good and durable WEC design
2017
In this paper, preliminarily a proposal for design guidelines for a “good” design of wave energy converter is presented and successively a small scale prototype of a wave energy converter including the buoyant electrical generator, the power electronics equipment and a sea water electrolyzer is designed on the basis of these guidelines and presented.