Search results for "nonlinear"
showing 10 items of 3684 documents
Polarization insensitive wavelength conversion of 40 Gb/s DPSK signals in a silicon germanium waveguide
2015
We demonstrate polarization insensitive FWM-based wavelength conversion of 40Gb/s DPSK signals in a SiGe waveguide, with 0.42-dB polarization-dependent loss. A 1.5-dB Dower nenaltv was measured at a BER of 10−9.
Nonlinear vibrations and hysteresis of micromachined silicon resonators designed as frequency-out sensors
1987
Experimental observation of nonlinear vibrations and hysteresis of micromachined silicon resonators is reported. The experimental results are explained using a simple model in which the restoring force acting in the resonator contains a small cubic term. The effects will impose a limit to the maximum amplitude which can be excited while still maintaining reliability of these devices as frequency-out sensors.
Properties of sintered Al substituted NdFeB magnets
1998
The effect of partial substitution of Fe by Al (Al, Al 2 O 3) on the magnetic properties and the corrosion resistance of the sintered NdFeB magnet has been investigated. With the increasing amount of Al, the anisotropy field and the saturation magnetization decrease, but the coercivity increases up to 4 at.% Al and further alloying of Al leads to a decrease of the coercivity. Different substances like Al (metallic Al or Al 2 O 3) modify the microstructure to different increase in the coercivity and especially to changes in the remanence. Alloying Al via metallic Al decreases the remanence, whereas via Al 2 O 3) up to 4 at.%0 Al increases it. The Al additions inhibit atmospheric corrosion o…
Stochastic resonance in a metal-oxide memristive device
2021
Abstract The stochastic resonance phenomenon has been studied experimentally and theoretically for a state-of-art metal-oxide memristive device based on yttria-stabilized zirconium dioxide and tantalum pentoxide, which exhibits bipolar filamentary resistive switching of anionic type. The effect of white Gaussian noise superimposed on the sub-threshold sinusoidal driving signal is analyzed through the time series statistics of the resistive switching parameters, the spectral response to a periodic perturbation and the signal-to-noise ratio at the output of the nonlinear system. The stabilized resistive switching and the increased memristance response are revealed in the observed regularities…
Optimized blue light generation in optically contacted walk-off compensated RbTiOAsO4 and KTiOP1−yAsyO4
1999
Abstract We study type II 1.32 μm second harmonic generation (SHG) in a RbTiOAsO 4 optically contacted walk-off compensated device. The reduction of the effective walk-off angle by a factor of 3.7 with respect to KTiOPO 4 for the same interaction leads to an enhancement by a factor of 10 of the conversion efficiency. A model is proposed for both type I and type II SHG in such a structure. The angular tuning curve is a multi-peaked one, as predicted by the model. The enhancement of the SHG conversion efficiency allows us to optimize the generation of blue laser light at 440 nm: a specially designed KTiOP 0.98 As 0.02 O 4 solid solution crystal achieves angular non-critical phase matching at …
Linear and nonlinear fractional hereditary constitutive laws of asphalt mixtures
2016
The aim of this paper is to propose a fractional viscoelastic and viscoplastic model of asphalt mixtures using experimental data of several tests such as creep and creep recovery performed at different temperatures and at different stress levels. From a best fitting procedure it is shown that both the creep one and recovery curve follow a power law model. It is shown that the suitable model for asphalt mixtures is a dashpot and a fractional element arranged in series. The proposed model is also available outside of the linear domain but in this case the parameters of the model depend on the stress level.
Kinetic Parameters for Thermal Degradation of Green Asparagus Texture by Unsteady-state Method
1998
An unsteady-state method was developed for estimating texture degradation during heating-cooling of green asparagus spears. The method used a mathematical model of heat transmission for time-temperature history estimation, and a nonlinear regression of texture measurements of asparagus spears to estimate kinetic parameters. The specific heat, conductivity and convective coefficient of green asparagus were determined experimentally and used In the mathematical model for temperature estimation. Values obtained were Ea = 76.19±0.13 kJ/mol and k 1158°C = 0.00528±0.00005 s -1 . Good agreement was found between predicted and observed texture values. The method was compared with the classical stea…
Simple equations for strength and deformability verification of tubular steel wind turbine towers
2021
Abstract Simple analytical expressions for a preliminary design of tubular steel wind turbine towers under flexure and shear are proposed. Expressions derived included local buckling effects, shear to moment interaction, ovalization of cross-section and inelastic rotation of foundation. A finite-element analysis with ABAQUS program was also conducted for examination of the ovalization effects and for the whole response of steel tube in flexure. Numerical and analytical results were compared with the experimental results of recent studies available in the literature, showing good agreement. The range of variable investigated refers to medium and large size steel wind tower with cylindrical s…
Second-harmonic generation in Langmuir–Blodgett monolayers of stilbazium salt and phenylhydrazone dyes
1988
The second-order nonlinear optical susceptibilities χ(2) of several phenylhydrazone and stilbazium salt dyes in Langmuir–Blodgett monolayers have been determined from second-harmonic-generation measurements. Three of the substances demonstrated χ(2) values greater than 10−6 electrostatic units, although two of the three did not absorb light significantly at the second-harmonic wavelength.
Ab initio study of the mechanical and electronic properties of scheelite-type XWO4(X = Ca, Sr, Ba) compounds
2017
The structural, mechanical, and electronic properties of scheelite-type CaWO4, SrWO4, and BaWO4 have been investigated using density-functional theory (DFT) within the generalized-gradient approximation (GGA). In particular, we have studied the effect of pressure in the crystal structure, elastic constants [Formula: see text], elastic moduli ([Formula: see text], [Formula: see text] and [Formula: see text]), and elastic anisotropy. We have also investigated the band structure of the three studied compounds and the effect of pressure in their electronic bandgap. The obtained results compare well with experimental results regarding the high-pressure (HP) behavior of the crystal structure. Th…