Search results for "Phase shift"
showing 10 items of 22 documents
Rho resonance, timelike pion form factor, and implications for lattice studies of the hadronic vacuum polarization
2020
We study isospin-1 P-wave ππ scattering in lattice QCD with two flavors of O(a) improved Wilson fermions. For pion masses ranging from mπ=265 MeV to mπ=437 MeV, we determine the energy spectrum in the center-of-mass frame and in three moving frames. We obtain the scattering phase shifts using Lüscher’s finite-volume quantization condition. Fitting the dependence of the phase shifts on the scattering momentum to a Breit-Wigner form allows us to determine the corresponding ρ mass mρ and gρππ coupling. By combining the scattering phase shifts with the decay matrix element of the vector current, we calculate the timelike pion form factor, Fπ, and compare the results to the Gounaris-Sakurai repr…
Biogenic habitat shifts under long-term ocean acidification show nonlinear community responses and unbalanced functions of associated invertebrates
2019
Este artículo contiene 8 páginas, 4 figuras.
New approach for harmonic mitigation in single-phase five-level CHBMI with fundamental frequency switching
2017
The main objective of this paper is to study and analyse the voltage output waveform of a multilevel inverter, to suggest a new approach for harmonic mitigation improving the converter performance. These last type of converters represent a new technology in the field of DC/AC electrical energy conversion, presenting advantages respect to the traditional converters. In fact, the multilevel power converters present a low harmonic content and a high voltage level. The paper considers a five-level single-phase cascaded H-bridge inverter and fundamental frequency modulation techniques. The voltage waveform analysis has allowed to identify a working area of the converter where there are lowest va…
Fatigue life prediction under wide band random loading
2004
In this paper, a method for the high-cycle fatigue life prediction of components subjected to gaussian, stationary, wide band random loading is presented. It allows the user to evaluate the fatigue life of components subjected to uniaxial stress states directly from the stress power spectral density (PSD), avoiding onerous simulations in time domain. The proposed method can be applied to random stress processes having PSD of any shape, and the fatigue life predictions obtained are more accurate than that provided by most of the frequency domain techniques proposed in literature.
Phase-shifting by means of an electronically tunable lens: quantitative phase imaging of biological specimens with digital holographic microscopy
2016
The use of an electronically tunable lens (ETL) to produce controlled phase shifts in interferometric arrangements is shown. The performance of the ETL as a phase-shifting device is experimentally validated in phase-shifting digital holographic microscopy. Quantitative phase maps of a section of the thorax of a Drosophila melanogaster fly and of human red blood cells have been obtained using our proposal. The experimental results validate the possibility of using the ETL as a reliable phase-shifter device.
Improvement of Hall Effect Current Transducer Metrological Performances in the Presence of Harmonic Distortion
2010
The performance of Hall effect current transducers (HECTs), under distorted waveform conditions, is usually characterized by means of a frequency response test. In this paper, it was investigated if frequency response is able to correctly evaluate the ratio and the phase errors under distorted conditions. Two HECTs, with the accuracy class level of 1% and 0.5%, respectively, were experimentally characterized under two conditions: 1) sinusoidal excitation with frequencies ranging from 50 to 750 Hz, which is the well-known frequency response test, and 2) nonsinusoidal excitation using fundamental frequency and one harmonic with adjusted amplitude and phase shift. It was found that ratio and p…
Microwave phase shifter based on fibre Bragg grating
1998
A variable delay line is presented for phased array antennas based on a fibre Bragg grating which has a uniform period and operates at constant optical wavelength. The Bragg wavelength of a localised part of the fibre grating is modified by straining the fibre, the optical carrier is reflected by the strained part of the grating and the time delay of the microwave modulating signal is determined by the position where the strain has been applied. In this initial experiment time delay variations up to 330 ps in the frequency range 1 – 14 GHz have been achieved.
Scalar mesons moving in a finite volume and the role of partial wave mixing
2012
Phase shifts and resonance parameters can be obtained from finite-volume lattice spectra for interacting pairs of particles, moving with nonzero total momentum. We present a simple derivation of the method that is subsequently applied to obtain the pi pi and pi K phase shifts in the sectors with total isospin I=0 and I=1/2, respectively. Considering different total momenta, one obtains extra data points for a given volume that allow for a very efficient extraction of the resonance parameters in the infinite-volume limit. Corrections due to the mixing of partial waves are provided. We expect that our results will help to optimize the strategies in lattice simulations, which aim at an accurat…
Measurement of edge residual stresses in glass by the phase-shifting method
2011
Abstract Control and measurement of residual stress in glass is of great importance in the industrial field. Since glass is a birefringent material, the residual stress analysis is based mainly on the photoelastic method. This paper considers two methods of automated analysis of membrane residual stress in glass sheets, based on the phase-shifting concept in monochromatic light. In particular these methods are the automated versions of goniometric compensation methods of Tardy and Senarmont. The proposed methods can effectively replace manual methods of compensation (goniometric compensation of Tardy and Senarmont, Babinet and Babinet–Soleil compensators) provided by current standards on th…
Phase shifting photoelasticity in white light
2007
The availability of image acquisition systems has led to the development of digital photoelasticity both in monochromatic and white light. In particular white light has been used mainly with the following methods: Spectral Content Analysis, RGB photoelasticity and phase shifting photoelasticity. Phase shifting photoelasticity in the colour domain has been used effectively for the determination of the isoclinic parameter in order to reduce the influence of the isochromatic fringes. The method has been also proposed for the determination of the isochromatic fringe order. This paper concerns the general characteristics of phase shifting photoelasticity in the colour domain. Special attention i…