Search results for "Waveform"

Functional Linear Models for the Analysis of Similarity of Waveforms

2023

In seismology methods based on waveform similarity analysis are adopted to identify sequences of events characterized by similar fault mechanism and propagation pattern. Seismic waves can be considered as spatially interdependent, three dimensional curves depending on time and the waveform similarity analysis can be configured as a functional clustering approach, on the basis of which the membership is assessed by the shape of the temporal patterns. For providing qualitative extraction of the most important information from the recorded signals, we propose the use of metadata, related to the waves, as covariates of a functional response regression model. The temporal patterns of this effect…

Split Bregman Method for Gravitational Wave Denoising

2014

This paper presents a progress report in our aim to develop a Total Variation algorithm for denoising of gravitational waves. These algorithms, are routinely employed in the context of image processing and they do not need any a priori information on the signals. We apply our method to two different types of numerically-simulated gravitational wave signals, namely burst produced from the core collapse of rotating stars and waveforms from binary black hole mergers, and present a preliminary assessment of its capabilities.

Geoacoustic Inversion with Drifting Buoys: Enverse 1997–98 Experiments (Marettimo Is.)

2000

Acoustic buoys were developed to allow the rapid determination of range-dependent bottom properties in a shallow water environment from the inversion of propagation measurements. The main features of the buoys are the large dynamic range, digital signal conditioning unit, global positioning system receiver and reliable radio data link. The buoys drift away from a broadband source receiving its pings at known positions. Single hydrophone, matched waveform, inversion techniques are applied to the received signals to invert for geoacoustic parameters. Eight prototypes were tested over the southern continental shelf off the island of Marettimo (Sicily) during the EnVerse 97 sea trials. Calibrat…

Detection of disbonds in multilayer structures by laser-based ultrasonic technique

2008

Adhesively bonded multi-layer structures are frequently used, mostly in the aerospace industry, for their structural efficiency. Nondestructive evaluation of bond integrity in these types of structures, both after manufacturing and for periodic inspection during service, is extremely important. A laser-based ultrasonic technique has been evaluated for non-contact detection of disbonds in aluminum multi-layer structures. Two configurations have been used to detect disbonded areas: pitch-catch with unidirectional guided wave scan and through-transmission with bidirectional scan. Guided wave scanning was done with a laser line source and air-coupled transducer sensing at 500 kHz, 1 ;MHz, and 2…

IL LASER SCANNER TERRESTRE E LA TECNOLOGIA FULL WAVEFORM PER LA MODELLAZIONE TRIDIMENSIONALE IN AMBITO GEOLOGICO

2014

P26-S Left and right motor cortical excitability and relationship to motor functions in healthy adolescents

2019

Background The interhemispheric difference in cortical excitability and its relationship to motor functions is unclear. Aim We examined the relationship between handedness, left and right motor cortex excitability and fine and gross motor functions in adolescence. Methods 28 healthy adolescents (age 16–19 years, 19 girls) were studied. Handedness was determined by the Waterloo Handedness Questionnaire. Motor threshold (MT) of the abductor pollicis brevis was measured on both hemispheres using biphasic stimulation, and on the left hemisphere also with monophasic stimulation. Box and block test (BBT) was used for manual dexterity, line run and standing long jump for gross motor tasks. Spearma…

The Partial Discharge Behavior of Different Materials under DC Periodic Stress

2019

The aim of the present work is to evaluate the PDs behavior by stressing a specimen with a new type of waveform named DCP. This waveform was proposed by the authors in a previous work with the aim to overcome the main issues of PDs under DC stress. In the previous work PDs test on Kapton specimen was performed. In this paper, we propose a new DCP test on a different insulating material, such as the XLPE. The obtained patterns and the acquired data have been evaluated in order to validate the DCP approach as a new method for PDs measure under constant stress. The behavior of the XLPE material has been reported and compared with the former measures obtained for Kapton material.

Partial discharge behavior under single phase half and full-bridge rectifier

2017

The aim of the present work is to simulate partial discharges (PDs) phenomena under voltage stress close to the Direct Current (DC) waveform. The employed waveforms have been realized by using a full-wave and a half-wave rectifiers. After that, in order to generate a steadier voltage supply, a capacitive filter has been inserted in the output of the half-wave rectifier. Simulations have been carried out by modifying a previous software used in the case of Alternating Current (AC). Finally, experimental tests have been carried out in order to validate simulation results.

Remote voltage synchronization for wireless Partial Discharge diagnostics

2016

The main objective of this paper is the assessment of the exact phase angle displacement of each Partial Discharge, PD, pulse with respect to the voltage reference waveform. Such problem also referred to as ‘synchronization’ is relevant when the cable is not accessible and the PD measure is carried out in wireless mode. It is well known, that the angle phase shift, due to the propagation phenomenon on the transmission line, can be calculated knowing the line type and length and typical operating conditions of the transmission line. The setup comprises a customized electronic device, the “Phase check”, a server to collect remote measurements and a Look up table to provide corrections to the …

Influence on PD Parameters due to Voltage Conducted Disturbances

2004

In the standard specification of ac dielectric-characteristic measurements of insulating materials, test voltage is prescribed as "approximately sinusoidal" when the highest acceptable deviation of the HV waveform, from the correct sinusoidal shape, is limited to a /spl plusmn/5% tolerance range of the crest factor value. In the field of partial discharge (PD) measurements and their statistical data processing, on which forecasts of long term behavior of components and their reliability are currently carried out, the results of elaborations depend on the voltage wave shape. In this paper, the errors in PD measurements, evaluated at industrial frequencies, due to applied voltages distorted b…