Search results for "Absorber"
showing 10 items of 53 documents
Mathematical Modeling and Optimization of a Vehicle Crash Test based on a Single-Mass
2014
In this paper mathematical modelling of a vehicle crash test based on a single mass is studied. The models under consideration consist of a single mass, a spring and/or a damper. They are constructed according to the measured vehicle speed before the collision and measured vehicle accelerations in three directions at the centre of gravity. A new model of nonlinear spring-mass-damper is also proposed to describe the crash. Simulation results are provided to show the effectiveness and applicability of the proposed methods.
A study of solar thermal absorber stack based on CrAlSiNx/CrAlSiNxOy structure by ion beams
2019
Renewable energies are foreseen as a major energy resource for next generations. Among several energy sources and technologies available, Concentrated Solar Power (CSP) technology has a great potential, but it needs to be optimised, in particular to reduce the costs, with an increase of the operating temperature and long term stability. This goal can be achieved by tailoring the composition and multilayer structure of films. In this work we present and discuss the results obtained from solar absorber coatings based on nitride/oxynitride structures. A four-layer film structure, W/CrAlSiNx(HA)/CrAlSiNxOy(LA)/SiAlOx, was deposited on stainless steel substrates using magnetron sputtering deposi…
Cascadability and reshaping properties of a saturable absorber inserted inside a RZ transmission line for future 160-Gbit/s all-optical 2R-regenerato…
2007
International audience; In this prospective work, we analyze the behavior of a quantum-well microcavity saturable absorber component cascaded into a 100-km SMF RZ transmission line in order to annihilate the ghost-pulse phenomenon in the following simplified “...010101...” 160-Gbit/s 2-bit pattern at 1555 nm. Recirculating-loop experiments show a maximal ghost-pulse extinction up to 11.6 dB as well as an intensity extinction ratio enhancement higher than 6 dB over at least 800 km of propagation.
Near 100% Renewable Island with sea wave energy. The case study of Pantelleria in Mediterranean sea
2016
The first aim of this work is to explore the possibility of the transition of a real islanded network from one that is “fuel-based” to a “renewable-based” one. This transition is analysed for the real MV/LV distribution system of the island of Pantelleria, in the Mediterranean Sea. Particularly, this work is focused on a Renewable source nowadays totally unused: wave energy. Thanks to the innovative generator prototype designed by Department of Energy of University of Palermo (Italy), wave energy is able to represent a primary source for the production of electric energy in the Mediterranean islands. The procedures applied in the present article, as well as the main equations used, are the …
Sound absorption prediction of linear damped acoustic resonators using a lightweight hybrid model
2019
International audience; A lightweight numerical method is developed to predict the sound absorption coefficient of resonators whose cross-section dimensions are significantly larger compared to the viscous and thermal boundary layer’s thicknesses. This method is based on the boundary layer theory and on the perturbations theory. According to the perturbations theory, in acoustical domains with large dimensions, the fluid viscosity and thermal conductivity only affect the boundary layers. The model proposed in this article combines the lossless Helmholtz wave equation derived from a perfect fluid hypothesis, with viscosity and thermal conductivity values of a real fluid to compute the sound …
Thermalization efficiency of superconducting absorbers for thermal X-ray microcalorimeters
2004
The persistence of long living quasiparticles created in the energy thermalization process can affect the performances of a thermal X-ray microcalorimeter with superconducting absorber. Numerical simulations indicate that in an ab- sorber made of high-purity Sn, operated at temperatures lower than 100 mK, up to 60% of the deposited energy can remain trapped in the quasiparticle system for a time much longer than the time scale of the thermal sensor response, producing a reduction of the SNR of the detector. Other pure superconductors can present the same problem and therefore a microscopic analysis of the physical properties can be useful to identify suitable absorbing materials and optimiz…
Spectral broadening by quasiparticle pile-up in X-ray microcalorimeters with superconducting absorbers
2004
Long-living quasiparticles can pile-up in a superconducting absorber of an X-ray microcalorimeter when photons are detected at high count rate. These quasiparticles can give a non-negligible contribution to the total heat capacity of the detector thus affecting the pulse height spectrum of detected photons. We investigated this effect with numerical simulations and evaluated the resulting spectral broadening as a function of the photon absorption rate, and the heat capacity of the detector for a NTD germanium microcalorimeter with pure Sn absorber.
Assessment of Renewable Sources for the Energy Consumption in Malta in the Mediterranean Sea
2016
The main purpose of this paper is to analyze the energy production in the Maltese islands, focusing on the employment of renewable energies in order to increase their energy independence. The main renewable source here proposed is wave energy: thanks to a strategic position, Malta will be able to produce electrical energy using an innovative type of Wave Energy Converter (WEC) based on the prototype of a linear generator realized by University of Palermo. The use of this new technology will be able to cut down the electrical energy production from traditional power plants and, consequently, the greenhouse gas emissions (GHG). Wave energy source and off-shore photovoltaic (PV) technology are…
Testing a linear ironless generator for the sea wave energy harvesting
2022
Wave energy represents a "new entry"in the renewable energy sector; however, it is believed that in near future sea wave might have a key role for the electrical energy production, thanks its huge energy potential. In this context, the paper suggests an innovative ironless linear generator, that can be used as main component inside a point absorber. In order to exploit the wave energy potential in the Mediterranean Sea, the Engineering Department of Palermo University realized a first small-scale prototype of the electrical linear generator, that is the main component for the energy conversion.
Reduction of cogging force in linear generators for wave energy harvesting
2022
Due to huge energy potential of sea waves, many technologies have been proposed in the last few years. Some concepts have been developed and sometimes also tested in the open sea. Some prototypes use linear generators to directly convert the vertical motion of buoys into electrical energy. This solution minimizes the numbers of energy conversion steps, increasing the energy efficiency. At the same time, the limited numbers of components could also increase the reliability of the wave energy converter. For this reason, the development of linear generators is considered with great interest. This paper investigated the cogging force, a magnetic force due to the interaction between the magnets …