Search results for " Elettroni"

A framework for assessing frequency domain causality in physiological time series with instantaneous effects.

2013

We present an approach for the quantification of directional relations in multiple time series exhibiting significant zero-lag interactions. To overcome the limitations of the traditional multivariate autoregressive (MVAR) modelling of multiple series, we introduce an extended MVAR (eMVAR) framework allowing either exclusive consideration of time-lagged effects according to the classic notion of Granger causality, or consideration of combined instantaneous and lagged effects according to an extended causality definition. The spectral representation of the eMVAR model is exploited to derive novel frequency domain causality measures that generalize to the case of instantaneous effects the kno…

Granger causality analysis of sleep brain-heart interactions

2014

We studied the networks of Granger causality (GC) between the time series of cardiac vagal autonomic activity and brain wave activities, measured respectively as the normalized high frequency (HF) component of heart rate variability and EEG power in the δ, θ, α, σ, β bands, computed in 10 healthy subjects during sleep. GC analysis was performed by vector autoregressive modeling, and significance of each link in the network was assessed using F-statistics. The whole-night analysis revealed the existence of a fully connected network of brain-heart and brain-brain interactions, with the ß EEG power acting as a hub which conveys the largest number of GC links between the heart and brain n…

Fabrication of Graphene Field Effect Transistors (GFET) possessing a photoelectrical response

2014

Electrical and optical properties of Graphene Field-Effect Transistors (GFETs) fabricated on sapphire

Photoelectrical response of Graphene Field Effect Transistors (GFETs)

2016

In this work, we present Graphene Field Effect Transistors (GFETs) with photoelectrical response due to the photovoltaiceffect. Our final aim is to use a GFET to down convert an optical to a radiofrequency signal. The technological steps used for the devices fabrication as well as the photoelectrical characterization will be reported. Photoelectrical measurements were performed by using a 405 nm laser diode source, whose output beam was pulse amplitude-modulated at 1.33 kHz by means of a laser driver. The electrical signal out of the GFETs (in a common source amplifier configuration) was measured using a lock-in amplifier synchronized to the same reference frequency of the laser driver. Thi…

Decoupled Control Scheme of Grid-Connected Split-Source Inverters

2017

During the last few years, single-stage power conversion systems has undergone a fast evolution to replace the conventional two-stage architecture, which includes a front-end dc-dc boost converter (BC) and an output voltage source inverter (VSI) [1]. This evolution has grown up to improve the overall system performance in terms of reducing its size, weight, and complexity. Most of these single-stage topologies and their different modulation schemes have been reviewed in [1]. Among these different single-stage options, the split-source inverter (SSI), shown in Figure 1, has been recently proposed in [2] as a single-stage dc-ac power converter topology to overcome some demerits in the other s…

Pathological voice analysis via digital signal processing

2015

The interest in pathological voice analysis for specific neurological diseases is growing up aiming to offer more Health-care tele monitoring services since new high performing electronic devices are available for the end-user. In this article we show some parameters that can be digitally extracted and analyzed from pathological voices, in order to find a distinctive sign of the Parkinson disease. As a result, we will show a parameter that gives some information about the Parkinson disease characterization, particularly for male patients. We will also discuss about the needed computational cost related to parameters extraction and elaboration, aiming to target a possible tough yet portable …

Measurement issues on harmonic analysis according to the IEC 61000-4-7

2022

The objective of this article is an analysis of measurement issues related to the implementation of digital signal processing techniques for harmonic analysis, by means of FFT algorithm with different interpolation algorithms (linear, quadratic and cubic) and different sampling rates. A comparative analysis is made on errors on harmonics measurement obtained in the various case study analyses. Such errors are compared with the IEC 61000-4-7 limits. The study is supported by both simulation and experimental tests; these last are performed with different acquisition boards for signals acquisition.

Quantification of Different Regulatory Pathways Contributing to Heartbeat Dynamics during Multiple Stimuli: a Proof of the Concept.

2019

The dynamical interplay between brain and heart is mediated by several feedback mechanisms including the central autonomic network and baroreflex loop at a peripheral level, also for a short-term regulation. State of the art focused on the characterization of each regulatory pathway through a single stressor elicitation. However, no studies targeted the actual quantification of different mediating routes leading to the generation of heartbeat dynamics, particularly in case of combined exogenous stimuli. In this study, we propose a new approach based on computational modeling to quantify the contribution of multiple concurrent stimuli in modulating cardiovascular dynamics. In this prelimina…

Towards Disentangling the Contribution of Different Pathways for the Regulation of Cardiac Activity: A Pilot Study

2020

Heartbeat is dynamically regulated through mediating routes associated with central and peripheral feedback mechanisms. Previous studies focused on the quantification of these mechanisms in the presence of a single stressor. In this pilot study we propose a model aimed to quantify the contribution of different heartbeat regulatory routes while multiple stressors are administrated to the subject. The model is tested with Heart rate Variability (HRV) series from 26 subjects undergoing physical and affective stressors. Results show that the physical stressor prevalently (74%) contributes in mediating cardiac vagal control dynamics in case of concurrent affective elicitation. These results may …