Search results for "electromagnetic [effect]"
showing 10 items of 555 documents
Surface Lattice Resonances in Self-Assembled Arrays of Monodisperse Ag Cuboctahedra
2019
Plasmonic metal nanoparticles arranged in periodic arrays can generate surface lattice plasmon resonances (SLRs) with high Q-factors. These collective resonances are interesting because the associated electromagnetic field is delocalized throughout the plane of the array, enabling applications such as biosensing and nanolasing. In most cases such periodic nanostructures are created via top-down nanofabrication processes. Here we describe a capillary-force-assisted particle assembly method (CAPA) to assemble monodisperse single-crystal colloidal Ag cuboctahedra into nearly defect-free >1 cm2 hexagonal lattices. These arrays are large enough to be measured with conventional ultraviolet-visibl…
Layer-wise and equivalent single layer models for smart multilayered plates
2014
Layer-wise and equivalent single layer plate models for magneto-electro-elastic multiphysics laminates are presented in a unified framework. They are based on variable kinematics and quasi-static behavior of the electromagnetic fields. The electromagnetic state of each single layer is preliminary determined by solving the corresponding governing equations coupled with the proper interface continuity and external boundary conditions. By so doing, the electromagnetic state is condensed into the plate kinematics and the layer governing equations are inferred by the principle of virtual displacements. This approach identifies effective mechanical layers, which are kinematically equivalent to th…
Electromagnetic radiated field measurements for partial discharge diagnostic
2004
Recently, improvements have been made in the diagnostic of electrical insulation systems by means of electric Partial Discharge (PD) standard measurements through a stochastic approach in the treatment of the acquired data: in this way, the identification of the defects as well as the separation of multiple defects simultaneously active, have been successfully performed. However, the standard PD measurement process can be affected by the well-known parasitic effects due to conducted noise whose spectrum can have characteristics similar to those of the measured signal. Moreover, the classic PD measurement system have to be suitable assembled on the Device Under Test (DUT) so determining a co…
Ultrabroadband single-cycle terahertz pulses with peak fields of 300 kV cm-1 from a metallic spintronic emitter
2017
To explore the capabilities of metallic spintronic thin-film stacks as a source of intense and broadband terahertz electromagnetic fields, we excite a W/CoFeB/Pt trilayer on a large-area glass substrate (diameter of 7.5 cm) by a femtosecond laser pulse (energy 5.5 mJ, duration 40 fs, wavelength 800 nm). After focusing, the emitted terahertz pulse is measured to have a duration of 230 fs, a peak field of 300 kV cm$^{-1}$ and an energy of 5 nJ. In particular, the waveform exhibits a gapless spectrum extending from 1 to 10 THz at 10% of amplitude maximum, thereby facilitating nonlinear control over matter in this difficult-to-reach frequency range and on the sub-picosecond time scale.
Partial Discharge on-line measures in cable's EPR insulation
2004
In this paper, an experimental study, carried out on an operating MV cable, is presented. The aim is to identify, locate and characterize defects in the cable's EPR (ethylene-propylene copolymer rubber) insulation. Direct partial discharge measurements have been compared to those obtained by high frequency electromagnetic field measures. The latter have been carried out using a sensor which does not require any galvanic connection with the system under test and that performs an intrinsic localization of the defect. Moreover, an analysis of an MV cable junction has been carried out using the same tools.
Sub-wavelength imaging of light confinement and propagation in SOI based photonic crystal devices
2006
A light source is coupled into photonic crystal devices and a near field optical probe is used to observe the electromagnetic field propagation and distribution at a sub-wavelength scale. Bloch modes are clearly observed.
Study of the angular acceptance of surface plasmon Bragg mirrors
2007
Surface plasmon based photonic devices are promising candidates for highly integrated optics. A surface plasmon (SP) is basically an electromagnetic wave confined in the interface between a metal and a dielectric, and is due to the interaction of the electromagnetic field with the surface bounded electron charges in the metal. A SP can propagate along the interface where it is confined (the propagation length being tens of micrometers in the visible range), but its associated electromagnetic field decreases exponentially in the perpendicular direction, in such a way that this vertical confinement makes SP very attractive for the design of optical devices in coplanar geometry. An important e…
Modelling of phase boundaries for large industrial FZ silicon crystal growth with the needle-eye technique
2003
In order to facilitate the numerical calculations of the phase boundaries in large industrial floating zone silicon crystal growth with the needle-eye technique, the chain of improved mathematical models is developed. The phase boundaries are solved in a partly transient way and the modelling improvements cover the open melting front, the inner triple point and the free melt surface. The view factors model is applied for the radiative heat transfer. The electromagnetic field is calculated with account of a multiple-slit inductor.
Some effects of a buried electricity transmission cable on bulk soil.
2007
A case study in NW Italy investigating an underground electric line (1 m depth triple cable at operative voltages 220-380 kV) measured electric fields in the surrounding soil virtually close to zero but magnetic fields (microTs) 20 times the background level. After 6 months, the influence radius around the cable on microbial activity (estimated by soil ATP), organic carbon, and total nitrogen follows exactly the inverse trend of the MF, shifting the biological activity with a lag distance of 5 m from the 220 kV cable.
Forward-backward equations for nonlinear propagation in axially invariant optical systems
2004
We present a novel general framework to deal with forward and backward components of the electromagnetic field in axially-invariant nonlinear optical systems, which include those having any type of linear or nonlinear transverse inhomogeneities. With a minimum amount of approximations, we obtain a system of two first-order equations for forward and backward components explicitly showing the nonlinear couplings among them. The modal approach used allows for an effective reduction of the dimensionality of the original problem from 3+1 (three spatial dimensions plus one time dimension) to 1+1 (one spatial dimension plus one frequency dimension). The new equations can be written in a spinor Dir…