Search results for "CAN"
showing 10 items of 25177 documents
Codimension growth of central polynomials of Lie algebras
2019
Abstract Let L be a finite-dimensional simple Lie algebra over an algebraically closed field of characteristic zero and let I be the T-ideal of polynomial identities of the adjoint representation of L. We prove that the number of multilinear central polynomials in n variables, linearly independent modulo I, grows exponentially like ( dim L ) n {(\dim L)^{n}} .
Generalised bisection method for optimum ultrasonic ray tracing and focusing in multi-layered structures
2021
Ultrasonic testing has been used for many decades, proving itself very efficient for detecting defects in many industrial sectors. The desire to apply ultrasonic testing to geometrically complex structures, and to anisotropic, inhomogeneous materials, together with the advent of more powerful electronics and software, is constantly pushing the applicability of ultrasonic waves to their limits. General ray tracing models, suitable for calculating the proper incident angle of single element probes and the proper time delay of phased array, are currently required. They can support the development of new imaging techniques, as Full Matrix Capture and Total Focusing Method, and the execution of …
First principles hybrid Hartree-Fock-DFT calculations of bulk and (001) surface F centers in oxide perovskites and alkaline-earth fluorides
2020
Valuable discussions with E. A. Kotomin are gratefully acknowledged. Research contribution of R. E. and A. I. P. has been performed within the framework of the EUROfusion Enabling Research project: ENR-MFE19.ISSP-UL-02 “Advanced experimental and theoretical analysis of defect evolution and structural disordering in optical and dielectric materials for fusion applications.” The views and opinions expressed herein do not necessarily reflect those of the European Commission.
Experimental investigation on different rainfall energy harvesting structures
2018
In this paper proposes an experimental comparison between different rainfall harvesting devices and the study of the corresponding electrical rectifying circuit. More in detail, three harvesting structures are considered: the cantilever, the bridge and the floating circle. For each of the proposed structure, different waveforms have been acquired and discussed. The processed data have been compared in order to suggest the best choice for the rectifying circuit, from the simplest one to the most endorsed in the technical literature.
Magnetic domain structure of La0.7Sr0.3MnO 3 thin-films probed at variable temperature with scanning electron microscopy with polarization analysis
2013
The domain configuration of 50 nm thick La0.7Sr0.3MnO3 films has been directly investigated using scanning electron microscopy with polarization analysis (SEMPA), with magnetic contrast obtained without the requirement for prior surface preparation. The large scale domain structure reflects a primarily four-fold anisotropy, with a small uniaxial component, consistent with magneto-optic Kerr effect measurements. We also determine the domain transition profile and find it to be in agreement with previous estimates of the domain wall width in this material. The temperature dependence of the image contrast is investigated and compared to superconducting-quantum interference device magnetometry …
Low energy nano diffraction (LEND) – A versatile diffraction technique in SEM
2019
Abstract Electron diffraction is a powerful characterization method that is used across different fields and in different instruments. In particular, the power of transmission electron microscopy (TEM) largely relies on the capability to switch between imaging and diffraction mode enabling identification of crystalline phases and in-depth studies of crystal defects, to name only examples. In contrast, while diffraction techniques have found their way into the realm of scanning electron microscopy (SEM) in the form of electron backscatter diffraction and related techniques, on-axis transmission diffraction is still in its infancy. Here we present a simple but versatile setup that enables a ‘…
Object size effect on the contact potential difference measured by scanning Kelvin probe method
2010
International audience; Contact potential difference (CPD) was measured by macroscopic Kelvin probe instrument and scanning Kelvin probe microscope on Al, Ni and Pt on ITO substrates at ambient conditions. CPD values measured by scanning Kelvin probe microscope and macroscopic Kelvin probe are close within the error of about 10-30% for large studied objects, whereas scanning Kelvin probe microscope signal decreases, when the object size becomes smaller than 1.4 m. CPD and electric field signals measured using many-pass technique allowed us to estimate the influence of electrostatic field disturbance, especially, in the case of small objects.
Laser Ultrasonics Inspection for Defect Evaluation on Train Wheel
2019
Abstract Passengers’ safety and in-service life of wheelset axles play an important role in railway vehicles. For this reason, periodic inspections are necessary. Among non-destructive techniques, ultrasonic ones are widely applied in this field. The main disadvantage of conventional ultrasonic techniques is that the overall inspection of wheels requires the train to be put out-of-service and disassembly each part, which is time-consuming and expensive. In this paper, a non-conventional non-contact laser ultrasonic inspection for train wheels is proposed. The proposed method uses a laser interferometer to receive the ultrasonic wave without contact. The receiving system allows choosing the …
Arsenic diffusion in relaxedSi1−xGex
2003
The intrinsic As diffusion properties have been determined in relaxed ${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ epilayers. The properties were studied as a function of composition x for the full range of materials with $x=0,$ 0.20, 0.35, 0.50, 0.65, 0.8, and 1. The activation enthalpy ${E}_{a}$ was found to drop systematically from 3.8 eV $(x=0)$ to 2.4 eV $(x=1).$ Comparisons with other impurity atom- and self-diffusion results in Si, Ge, and SiGe show that both interstitials and vacancies contribute as diffusion vehicles in the composition range $0l~xl~0.35$ and that vacancy mechanism dominates diffusion in the composition range $0.35lxl~1.$
The effects of the additive of Eu ions on elastic and electric properties of BaTiO3ceramics
2016
ABSTRACTThe BaTiO3 and BaTiO3+X%wt.Eu2O3 (X = 1, 2, 3) ceramics were prepared by a solid phase reaction. The structural and morphology studies were carried out by means of an X-ray diffraction technique and scanning electron microscopy, respectively. Elastic moduli were determined with the use of an ultrasonic method. The dielectric permittivity (ϵ′) and tanδ as a function of composition and temperature were investigated. The increasing concentration of Eu ions leads to a slight shift of the Curie temperature and changes the characteristics of ϵ′ and tanδ. The structural, mechanical and dielectric properties of the BTEX ceramics were discussed in terms of microstructure and dopants contents.