Search results for "electromagnetic"

Luminescence and Transient Optical Absorption in CdWO<sub>4</sub>

1997

Modeling of ITER TF cooling system through 2D thermal analyses and enthalpy balance

2017

Abstract The winding pack of the ITER Toroidal Field (TF) coils is composed of 134 turns of Nb3Sn Cable in Conduit Conductor (CICCs) wound in 7 double pancakes and cooled by supercritical helium (He) at cryogenic temperature. The cooling of the Stainless Steel (SS) case supporting the winding pack is guaranteed by He circulation in 74 parallel channels. A 2D approach to compute the temperature distribution in the ITER TF winding pack is here proposed. The TF is divided in 32 poloidal segments, for each segment the corresponding 2D model is built and a thermal analysis is performed applying the corresponding nuclear heating computed with MCNP code considering the latest design updates, such …

Evidence for a Double Doping Regime in Nd:YAG nanopowders

2009

Nanopowders of Yttrium Aluminium Garnet doped with neodymium (Nd:YAG) were investigated by X-Ray Absorption Fine Structure (XAFS) at the Nd LIII-edge in the 1.3 - 20.8 % doping range. XANES spectra appear similar in the full range of the Nd concentration. However, a significant decrease in the white line intensity of XANES is revealed as the quantity of Nd doping ions increases. Plotting the white line intensity as a function of Nd doping ions reveals two linear trends with two different slopes, identifying a threshold value where the neodymium concentration reaches 5 at.% This experimental finding provides support for the existence of a double doping regime in Nd:YAG nanopowders.

Magneto-Electro-Elastic Bimorph Analysis by the Boundary Element Method

2008

The influence of the magnetic configuration on the behavior of magneto-electro-elastic bimorph beams is analyzed by using a boundary element approach. The problem is formulated by using the generalized displacements and generalized tractions. The boundary integral equation formulation is obtained by extending the reciprocity theorem to magneto-electro-elastic problems; it is numerically implemented by using the boundary element method multidomain technique to address problems involving nonhomogeneous configurations. Results under different magnetic configurations are compared highlighting the characteristic features of magnetopiezoelectric behavior particularly focusing on the link between …

A Magnetostrictive Electric Power Generator for energy harvesting from traffic: Design and experimental verification

2015

In the last decades, the growth in energy demand, the decrease of fossil fuels available in the market and the impact of anthropogenic factors on climate change has given new impulse to research on renewable energy systems, particularly those known as energy harvesting devices (EHDs) [1]. A large number of EHDs have been proposed, using different operating principle [1-4]. Among them, piezoelectric and magnetostrictive seem to be particularly suitable for the application in EHD. In these materials the application of external mechanical stress induces a change in the level of magnetization and therefore an electromotive force (emf) can be generated and collected in order to produce electrica…

Colloidal plasmonic back reflectors for light trapping in solar cells.

2014

A novel type of plasmonic light trapping structure is presented in this paper, composed of metal nanoparticles synthesized in colloidal solution and self-assembled in uniform long-range arrays using a wet-coating method. The high monodispersion in size and spherical shape of the gold colloids used in this work allows a precise match between their measured optical properties and electromagnetic simulations performed with Mie theory, and enables the full exploitation of their collective resonant plasmonic behavior for light-scattering applications. The colloidal arrays are integrated in plasmonic back reflector (PBR) structures aimed for light trapping in thin film solar cells. The PBRs exhib…

Hygrothermal ageing of reprocessed polylactide

2012

[EN] The influence of an accelerated hygrothermal ageing simulation test on a commercial PLA and its three subsequent mechanically-reprocessed materials was studied. The analysis was focused on the water diffusion kinetics and the physico-chemical changes induced by the hygrothermal degradation. Water diffusion proceeded faster than chain relaxation processes, as defined by a Case II absorption model. It was proved that the water diffusion rate decreased with subsequent reprocessing cycles and increased with higher hygrothermal ageing temperatures. Hydrolytic chain scission provoked significant molar mass decays and consequent general losses of thermal and mechanical performance. The rearra…

Tailoring the microstructure and mechanical properties of Ti–Al alloy using a novel electromagnetic stirring method

2006

The effect of melt convection during the solidification of Ti45Al55 alloys was investigated in terms of microstructure evolution and the resulting mechanical properties. The samples were subjected to conventional induction melting as well as enhanced melt stirring by an external magnetic field using a specially designed floating zone arrangement. The stirred samples showed a significant improvement of plastic deformability. A strong change in the morphology from dendritic to spherical and an increased properitectic phase fraction were observed after stirring.

EMI shielding effects of carbon nanotube cellulose nanocomposite

2010

Electromagnetic interference shielding is an important aspect of modern communication and computer technology. Carbon nanotube cellulose nanocomposite (CNTCNC) provides a novel material as an alternative to traditional metal-based shields for EMI shielding. Stratified structures containing CNTCNC layers combined with existing commercial lossy materials (like ferrite sheets) form effective EMI shields without lowering the signal integrity performance. Significant improvement in shielding effectiveness in stacked CNTCNC layers is noteworthy. CNTCNC is essentially like paper when it comes to flexibility and hence it can be easily conformed to the mechanical structure of the device in need of s…

Modelling nanoparticles formation in the plasma plume induced by nanosecond pulsed lasers

2012

International audience; Nanoparticles formation in a laser-induced plasma plume in the ambient air has been investigated by using numerical simulations and physical models. For high irradiances, or for ultrashort laser pulses, nanoparticles are formed by condensation, as fine powders, in the expanding plasma for very high pairs of temperature and pressure. At lower irradiances, or nanosecond laser pulses, another thermodynamic paths are possible, which cross the liquid-gas transition curve while laser is still heating the target and the induced plasma. In this work, we explore the growth of nanoparticles in the plasma plume induced by nanosecond pulsed lasers as a function of the laser irra…