Search

The excessive noise level at the interior of aircrafts’ cabins is an important issue, that can affect the comfort of the passengers during flight. Although modern aircrafts are manufactured using technologically advanced soundproofing materials and quitter engines, the Sound Pressure Levels (SPL) in the cabin can sometimes exceed 80 dB. Especially in tilt-rotor aircrafts, the cabin SPL can reach 90 dB-95 dB, because of the existence of low frequency harmonics that are related to the rotor’s Blade Passage Frequency (BPF) and cannot be attenuated by conventional passive techniques because of weight and volume issues. For this reason, the use of Active Noise Control Systems (ANCS) in such aircrafts is a very promising method in order to reduce SPL without increasing the aircraft’s weight and the fuel consumption. The combination of local ANCS is being investigated in this work for global noise control around all seats. Two different ANC architectures have been modeled using FEM. The results of 2D and 3D simulations have shown that both ANC architectures create a more than 10 dB quiet zone in front of the seat’s headrest for a multi-tone acoustic disturbance. However, the multichannel approach, where systems of adjacent seats cooperate with each other, can achieve even bigger SPL attenuation, more uniform quiet zones in combination with the usage of less microphones comparing to the stand-alone systems. Thus, the present work proposes an efficient and easily implemented solution for the active noise control around the seats’ headrests of small aircraft cabins.

In present work an Active Noise Control System (ANCS) mounted on the headrest of an aircraft’s seat is proposed. It is based on the non-linear FsLMS algorithm alongside with a linear extrapolation technique used to estimate the acoustic pressure around the passenger’s ears. In order to check system’s effectiveness, real-time experiments took place inside an aircraft’s cabin mock-up for an acoustic disturbance measured during the flight of a tilt-rotor aircraft. The results have shown a more than 10 dB attenuation of different BPF harmonics and a significant SPL reduction that varies from 8 dB to 11 dB around the passenger’s ears. &nbsp

Poster Session-Amoruso-SpaceEdge a service-based approach to onboard payload data processing and autonomous workflows

Sleep spindles, defining oscillations of stage II non-rapid eye movement sleep (N2), mediate sleep-dependent memory consolidation. Spindles are disrupted in several neurodevelopmental, neuropsychiatric, and neurodegenerative disorders characterized by cognitive impairment. Increasing spindles can improve memory suggesting spindles as a promising physiological target for the development of cognitive enhancing therapies. This effort would benefit from more comprehensive and spatially precise methods to characterize spindles. Spindles, as detected with electroencephalography (EEG), are often widespread across electrodes. Available evidence, however, suggests that they act locally to enhance cortical plasticity in the service of memory consolidation. Here, we present a novel method to enhance the spatial specificity of cortical source estimates of spindles using combined EEG and magnetoencephalography (MEG) data constrained to the cortex based on structural MRI. To illustrate this method, we used simultaneous EEG and MEG recordings from 25 healthy adults during a daytime nap. We first validated source space spindle detection using only EEG data by demonstrating strong temporal correspondence with sensor space EEG spindle detection (gold standard). We then demonstrated that spindle source estimates using EEG alone, MEG alone and combined EEG/MEG are stable across nap sessions. EEG detected more source space spindles than MEG and each modality detected non-overlapping spindles that had distinct cortical source distributions. Source space EEG was more sensitive to spindles in medial frontal and lateral prefrontal cortex, while MEG was more sensitive to spindles in somatosensory and motor cortices. By combining EEG and MEG data this method leverages the differential spatial sensitivities of the two modalities to obtain a more comprehensive and spatially specific source estimation of spindles than possible with either modality alone.

Επιστημονικές μελέτες έχουν δείξει ότι η μέτρηση της ποιότητας υπηρεσίας (QoS) δεν αρκεί για να υπολογιστεί η ευχαρίστηση ή η δυσαρέσκεια ενός χρήστη ως προς τις υπηρεσίες που του παρέχονται από το διαδίκτυο και τα συστήματα κινητών επικοινωνιών. Εξαιτίας αυτού, όλο και περισσότερες εταιρίες παροχής υπηρεσιών διαδικτύου προσπαθούν να αναπτύξουν τρόπους και μεθόδους υπολογισμού της ποιότητας εμπειρίας του χρήστη (QoE). Μια τέτοια εταιρία είναι και η Netflix, η οποία έχει αναπτύξει τον αλγόριθμο VMAF για τον υπολογισμό, μέσω διαφόρων τεχνικών, της ικανοποίησης των πελατών της από τις υπηρεσίες video streaming που παρέχει. Για την δημιουργία αυτού του αλγορίθμου, συγκέντρωσε τις αξιολογήσεις μερικών χρηστών για προκατασκευασμένα βίντεο σε ελεγχόμενες συνθήκες προβολής. Στόχος αυτής της πτυχιακής είναι η θεωρητική μελέτη του αλγορίθμου της Netflix και η πειραματική αξιολόγηση του. Αναπτύχθηκε εργαλείο για την συλλογή υποκειμενικών μετρήσεων οι οποίες αντιπαραβλήθηκαν με την απόδοση του αλγορίθμου. Οι μετρήσεις που προέκυψαν έδωσαν σημαντικές απαντήσεις σε σχέση με την απόδοση του αλγορίθμου αλλά και τον συσχετισμό των παραμέτρων που υπεισέρχονται στην μέτρηση της ποιότητας εμπειρίας. Scientific studies have shown that QoS is not enough to measure the satisfaction or the displeasure of a user for services, that are provided by internet and mobile communications systems. Because of this, more and more Internet service companies are trying to develop ways and methods for calculating user experience quality (QoE). Netflix has developed the VMAF algorithm to calculate, through various techniques, customer satisfaction from its video streaming services. To run this algorithm, it gathered the ratings of some users from prefabricated videos in controlled viewing conditions. The aim of this dissertation is the theoretical study of the Netflix algorithm and its experimental evaluation. A tool was developed for the collection of subjective measurements that were compared with the performance of the algorithm. The resulting measurements gave important answers to the performance of the algorithm but also to the correlation of the parameters involved in measuring the quality of the experience.

Background: Multiple facets of sleep neurophysiology, including electroencephalography (EEG) metrics such as non-rapid eye movement (NREM) spindles and slow oscillations (SO), are altered in individuals with schizophrenia (SCZ). However, beyond group-level analyses which treat all patients as a unitary set, the extent to which NREM deficits vary among patients is unclear, as are their relationships to other sources of heterogeneity including clinical factors, illness duration and ageing, cognitive profiles and medication regimens. Using newly collected high density sleep EEG data on 103 individuals with SCZ and 68 controls, we first sought to replicate our previously reported (Kozhemiako et. al, 2022) group-level mean differences between patients and controls (original N =130). Then in the combined sample ( N =301 including 175 patients), we characterized patient-to-patient variability in NREM neurophysiology., Results: We replicated all group-level mean differences and confirmed the high accuracy of our predictive model (Area Under the ROC Curve, AUC = 0.93 for diagnosis). Compared to controls, patients showed significantly increased between-individual variability across many (26%) sleep metrics, with patterns only partially recapitulating those for group-level mean differences. Although multiple clinical and cognitive factors were associated with NREM metrics including spindle density, collectively they did not account for much of the general increase in patient-to-patient variability. Medication regimen was a greater (albeit still partial) contributor to variability, although original group mean differences persisted after controlling for medications. Some sleep metrics including fast spindle density showed exaggerated age-related effects in SCZ, and patients exhibited older predicted biological ages based on an independent model of ageing and the sleep EEG., Conclusion: We demonstrated robust and replicable alterations in sleep neurophysiology in individuals with SCZ and highlighted distinct patterns of effects contrasting between-group means versus within-group variances. We further documented and controlled for a major effect of medication use, and pointed to greater age-related change in NREM sleep in patients. That increased NREM heterogeneity was not explained by standard clinical or cognitive patient assessments suggests the sleep EEG provides novel, nonredundant information to support the goals of personalized medicine. Collectively, our results point to a spectrum of NREM sleep deficits among SCZ patients that can be measured objectively and at scale, and that may offer a unique window on the etiological and genetic diversity that underlies SCZ risk, treatment response and prognosis.

Sleep spindles are believed to mediate sleep-dependent memory consolidation, particularly when coupled to neocortical slow oscillations. Schizophrenia is characterized by a deficit in sleep spindles that correlates with reduced overnight memory consolidation. Here, we examined sleep spindle activity, slow oscillation-spindle coupling, and both motor procedural and verbal declarative memory consolidation in early course, minimally medicated psychosis patients and non-psychotic first-degree relatives. Using a four-night experimental procedure, we observed significant deficits in spindle density and amplitude in patients relative to controls that were driven by individuals with schizophrenia. Schizophrenia patients also showed reduced sleep-dependent consolidation of motor procedural memory, which correlated with spindle density. Contrary to expectations, there were no group differences in the consolidation of declarative memory on a word pairs task. Nor did the relatives of patients differ in spindle activity or memory consolidation compared with controls, however increased consistency in the timing of SO-spindle coupling were seen in both patient and relatives. Our results extend prior work by demonstrating correlated deficits in sleep spindles and sleep-dependent motor procedural memory consolidation in early course, minimally medicated patients with schizophrenia, but not in first-degree relatives. This is consistent with other work in suggesting that impaired sleep-dependent memory consolidation has some specificity for schizophrenia and is a core feature rather than reflecting the effects of medication or chronicity.