0000000000502419
AUTHOR
Giuseppe Rizzo
Role of prenatal magnetic resonance imaging in fetuses with isolated severe ventriculomegaly at neurosonography: A multicenter study.
Objective: The aim of this study was to report the rate of additional anomalies detected exclusively at prenatal magnetic resonance imaging (MRI) in fetuses with isolated severe ventriculomegaly undergoing neurosonography. Method: Multicenter, retrospective, cohort study involving 20 referral fetal medicine centers in Italy, United Kingdom, Spain and Denmark. Inclusion criteria were fetuses affected by isolated severe ventriculomegaly (≥15 mm), defined as ventriculomegaly with normal karyotype and no other additional central nervous system (CNS) and extra-CNS anomalies on ultrasound. In all cases, a multiplanar assessment of fetal brain as suggested by ISUOG guidelines on fetal neurosonogra…
Time Evolution of Partial Discharges in a Dielectric Subjected to the DC Periodic Voltage
Partial discharge (PD) detection can be considered one of the most useful tools for assessing the insulation conditions of the power apparatus in high-voltage systems. Under AC conditions, this analysis is widely employed in online and offline tests, such as type tests or commissioning, and can be carried out by applying the phase-resolved PD (PRPD) method, since the patterns can give information about the defect classification. Under DC voltages, the classic pattern recognition method cannot be performed, and the measurements show complexities related to the nature of the phenomena. For this reason, to date, a standard for PD measurements under DC does not exist. In previous papers, a new …
Pulsed Electro-Acoustic space charge apparatus – qualifying, testing and monitoring of insulation for HVDC cables and accessories
Use of Time-Frequency map combined with DBSCAN algorithm for separation of partial discharge pulses under DC voltage
The Phase-Resolved-Partial-Discharge pattern (PRPD) is a conventional technique used for the evaluation of partial discharges (PD) phenomena in High-Voltage-Alternating-Current (HVAC) systems. This map is constructed by plotting the peak of each detected pulses as a function of the phase angle of the supply voltage. Therefore it is obvious that this technique cannot be used for the analysis of data from PD mesaurement under different supply voltage condition (DC). The aim of this paper is to evaluate the application of the Time-Frequency map (TF map) for the analysis of a dataset obtained from PD measurement under DC voltage. A density-based clustering algorithm was also used to gain more i…
Performances of a PCB-based Loop Antenna Inductive Sensor for Partial Discharges Detection
This paper presents the test results of an electrically small loop antenna sensor towards detecting the radiated magnetic field due to partial discharge (PD) activities. The loop antenna prototype was printed on an FR-4 substrate with a thickness of 1.6 mm, featuring a compact size of 20 mm times20 mm times1.7 mm. The proposed sensor, initially simulated with Ansys HFSS software, has a resonant frequency of about 100 MHz. Its detection capability for three types of partial discharges (i.e., corona, surface and internal PDs) has been evaluated. Laboratory experiments showed that the evaluated loop spiral antenna is appropriate for the detection of the three types of PDs. Indeed, the results …
Predictability of PD inception in defects included in HVDC cables by conductivity models calibrated through experiments
To date, there are several methods for calculating the electric field distribution within a dielectric layer subjected to HVDC voltage. However, experimental techniques for evaluating the accuracy of models for calculating the electric field, such as space charge measurement, are often not precise enough to be used for this purpose. At the same time, the knowledge of Partial Discharge (PD) phenomenon occurring under HVDC stress is also not as developed as that of PD under HVAC voltage. The main goal of this research is to study the effectiveness of dielectric conductivity models to forecast the inception condition for PD under load and HVDC voltage stress. This study has been carried out by…
Risk factors associated with adverse fetal outcomes in pregnancies affected by Coronavirus disease 2019 (COVID-19): a secondary analysis of the WAPM study on COVID-19.
Abstract Objectives To evaluate the strength of association between maternal and pregnancy characteristics and the risk of adverse perinatal outcomes in pregnancies with laboratory confirmed COVID-19. Methods Secondary analysis of a multinational, cohort study on all consecutive pregnant women with laboratory-confirmed COVID-19 from February 1, 2020 to April 30, 2020 from 73 centers from 22 different countries. A confirmed case of COVID-19 was defined as a positive result on real-time reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay of nasal and pharyngeal swab specimens. The primary outcome was a composite adverse fetal outcome, defined as the presence of either abortion (pre…
Investigation of PCB-based Inductive Sensors Orientation for Corona Partial Discharge Detection
This paper presents an experimental investigation of two different printed circuit board (PCB) inductive sensors, with meander and non-spiral shapes, to assess their capabilities and best orientation for corona partial discharge (PD) detection. First, simulations with the Ansys HFSS software are performed in order to evaluate the equivalent electrical circuit of the two sensors and their 2d radiation patterns. The meander sensors presented a resonant frequency of 600 MHz, while it was around 1.1 GHz for the non-spiral. The 2d radiation pattern showed that better sensitivity is achieved when the inductive sensor is oriented 90 degrees with respect to the PD source. Experimental tests showed …