Real-time geophysical applications with Android GNSS raw measurements

The number of Android devices enabling access to raw GNSS (Global Navigation Satellite System) measurements is rapidly increasing, thanks to the dedicated Google APIs. In this study, the Xiaomi Mi8, the first GNSS dual-frequency smartphone embedded with the Broadcom BCM47755 GNSS chipset, was employed by leveraging the features of L5/E5a observations in addition to the traditional L1/E1 observations. The aim of this paper is to present two different smartphone applications in Geoscience, both based on the variometric approach and able to work in real time. In particular, tests using both VADASE (Variometric Approach for Displacement Analysis Stand-alone Engine) to retrieve the 3D velocity of a stand-alone receiver in real-time, and VARION (Variometric Approach for Real-Time Ionosphere Observations) algorithms, able to reconstruct real-time sTEC (slant total electron content) variations, were carried out. The results demonstrate the contribution that mass-market devices can offer to the geosciences. In detail, the noise level obtained with VADASE in a static scenario-few mm/s for the horizontal components and around 1 cm/s for the vertical component-underlines the possibility, confirmed from kinematic tests, of detecting fast movements such as periodic oscillations caused by earthquakes. VARION results indicate that the noise level can be brought back to that of geodetic receivers, making the Xiaomi Mi8 suitable for real-time ionosphere monitoring

Morphological updating on the basis of integrated DTMs: study on the Albano and Nemi craters

The Colli Albani Volcano has recently developed particular interest in the geophysical community for some peculiar characteristics imputable to a recent residual volcanic activity, thus evidencing that it cannot be considered extinguished yet. On April 2006 an airborne laser scanning (ALS) survey of the Albano and Nemi craters has been carried out to obtain a high resolution digital terrain model (DTM) of the area. We have compared the accuracy of the ALS heights with those obtained by a fast GPS kinematic survey, obtaining maximum deviation within 50 cm. Then, we have integrated the ALS survey of the craters and the bathymetry of the Albano lake to achieve a complete DTM, useful for morphological studies. In addition, with a GNSS/RTK survey (July 2007) we have estimated the Albano and Nemi mean lake levels respectively at 288.16 m and 319.02 m (asl). Based on the integrated DTM and the newly estimated water level values, we have evaluated about 21.7 106 of m3 the water volume loss of the Albano lake from 1993 to 2007, with an average rate of about 1.6 106 m3/yr. © 2008, de Gruyter. All rights reserved

Un'ontologia dell'opera musicale, ripartendo da Ingarden

The recent philosophical debate about the musical ontology, between Platonist and Nominalist positions, has to face several unsurmountable objections. The aesthetics of Roman Ingarden, in spite of intrinsic limitations, can be considered in order to relaunch the research about the ontological status of musical works. Three Ingarden's ideas seem particularly useful: the work of music as pure intentional object, as scheme with many points of indeterminacy and as object founded on score, performance or recording. A comparison arises with the theory of documentality proposed by Maurizio Ferraris

Annotazioni sulla fenomenologia della tonalità nel pensiero di Giovanni Piana

Giovanni Piana's phenomenology of music was directed against any conventionalist point of view about the musical experience. According to Piana, each compositional system depends on the phenomenological structure of sound that determines the musical perception. Tonal system is not prescribed by natural laws, however it is based on the essential difference between consonance and dissonance. So the perceptual meaning of a tonal piece is not founded on subjective (culturally acquired) habitudes, but on phenomenological data

L'ermeneutica tra musica e diritto

This paper proposes a comparison between legal hermeneutics and hermeneutics of music from a philosophical point of view. In order to examine similarities and differences between interpretation of written laws and intepretation of musical scores, some theoretical conceptions are exploited: Emilio Betti's general classification of intepretation, Hans-Georg Gadamer's idea of hermeneutical representation and application, Roman Ingarden's idea of aesthetical concretization. The linguistic essence of musical intepretations and performances is discussed and criticized.L'articolo propone un confronto tra ermeneutica giuridica ed ermeneutica della musica da un punto di vista filosofico. Allo scopo di esaminare somiglianze e differenze tra l'interpretazione di leggi scritte e l'interpretazione di partiture musicali, vengono utilizzate alcune concezioni teoriche: la classificazione generale dell'interpretazione di Emilio Betti, l'idea di rappresentazione e applicazione ermeneutica di Hans-Georg Gadamer e l'idea di concretizzazione estetica di Roman Ingarden. L'essenza linguistica delle interpretazioni e delle esecuzioni musicali è posta in discussione e criticata

Fenomenologia, cognitivismo e teoria musicale

This paper explores the relationships between phenomenology, cognitive sciences, and music theory. West Coast school of phenomenology, by subscribing a Fregean reading of Husserl, interpreted Husserlian philosophy as strictly related to cognitive computationalism (Fodor) and Artificial Intelligence project (Minsky). In his musicological research, David Lewin was involved in this suggestion and modeled mental actions to formalize musical perceptions. The study of phenomenological intentionality and time-consciousness can be useful to improve Lewin’s model. Furthermore, the idea of embodied cognition is noteworthy in order to analyze motor intentionality in musical experiences

Foucault e l’arte moderna

Nell'opera di Foucault, nei suoi volumi pubblicati in vita o nei suoi corsi che stanno per essere pubblicati postumi, non è possibile trovare un testo importante dedicato specificamente e interamente all'arte. Se si intende per estetica, secondo consuetudine, una filosofia dell'arte trattata oltretutto sistematicamente, in Foucault non si rintraccia appunto un'estetica. Tuttavia nei suoi scritti (maggiori o minori, pubblicati o inediti) si rinvengono molto spesso riferimenti all'arte: richiami talvolta di notevole interesse e di una qualche ampiezza. Si rinviene inoltre il termine "estetica", sia pure usato in un'accezione del tutto particolare all'interno dell'espressione "estetica dell'esistenza". Con ciò Foucault non vuole alludere affatto a un vivere nell'estetismo, né a qualcosa che abbia a che fare in senso proprio con l'artisticità: anche se forse, in un certo modo, la questione dell'arte vi è comunque sollecitata

Real-time detection of tsunami ionospheric disturbances with a stand-alone GNSS receiver. A preliminary feasibility demonstration

It is well known that tsunamis can produce gravity waves that propagate up to the ionosphere generating disturbed electron densities in the E and F regions. These ionospheric disturbances can be studied in detail using ionospheric total electron content (TEC) measurements collected by continuously operating ground-based receivers from the Global Navigation Satellite Systems (GNSS). Here, we present results using a new approach, named VARION (Variometric Approach for Real-Time Ionosphere Observation), and estimate slant TEC (sTEC) variations in a real-time scenario. Using the VARION algorithm we compute TEC variations at 56 GPS receivers in Hawaii as induced by the 2012 Haida Gwaii tsunami event. We observe TEC perturbations with amplitudes of up to 0.25 TEC units and traveling ionospheric perturbations (TIDs) moving away from the earthquake epicenter at an approximate speed of 316 m/s. We perform a wavelet analysis to analyze localized variations of power in the TEC time series and we find perturbation periods consistent with a tsunami typical deep ocean period. Finally, we present comparisons with the real-time tsunami MOST (Method of Splitting Tsunami) model produced by the NOAA Center for Tsunami Research and we observe variations in TEC that correlate in time and space with the tsunami waves

An analysis of multi-GNSS observations tracked by recent Android smartphones and smartphone-only relative positioning results

In this study we assess the quality of multi-GNSS observations of recent Android smartphones. The results reveal a significant drop of smartphone carrier-to-noise density ratio (C/N0) with respect to geodetic receivers, and discernible differences among constellations and frequency bands. We show that the higher the elevation of the satellite, the larger discrepancy in C/N0 between the geodetic receivers and smartphones. Thus we show that a C/N0 weighting scheme may be superior to the elevation dependent one usually adopted for GNSS observations. We also discover that smartphone code pseudoranges are noisier by about one order of magnitude as compared to geodetic receivers, and that the code signals on L5 and E5a outperform those on L1 and E1, respectively. It is shown that smartphone phase observations are contaminated by the effects that can destroy the integer property and time-constancy of the ambiguities. There are long term drifts detected for GPS L5, Galileo E1, E5a and BDS B1 phase observations of Huawei P30. We highlight competitive phase noise characteristics for the Xiaomi Mi 8 when compared to the geodetic receivers. We also reveal a poor quality of other than GPS L1 phase signals for the Huawei P30 smartphones related to the unexpected drifts of the observations. Finally, the positioning experiment proves that it is feasible to obtain a precise cm-level solution of a smartphone to smartphone relative positioning with fixed integer ambiguities

GPS Seismology for a moderate magnitude earthquake: Lessons learned from the analysis of the 31 October 2013 ML6.4 Ruisui (Taiwan) earthquake

The 31 October 2013 ML 6.4 Ruisui earthquake was well recorded by twelve 50-Hz, four 20-Hz and thirteen 1-Hz GPS receivers, and twenty-five strong motion stations located within the epicentral distance of 90 km in eastern Taiwan. Kinematic positioning solutions estimated by four GNSS software (TRACK, RTKLIB, GIPSY, VADASE) are used to derive the seismic waveforms and the co-seismic displacements for this event; strong motion accelerometers are used to verify the capability of high rate GPS to detect seismic waves generated by this earthquake. Results show that the coordinate repeatability of the GPS displacements time series are ~6 mm and ~20 mm standard deviation in the horizontal and vertical components respectively, after applying spatial filtering. The largest co-seismic displacement derived from high-rate GPS is nearly 15 centimeter at 5 km northeast of the epicenter. S waves and surface waves are successfully detected by motions of high-rate GPS and double-integrated accelerometers within the 15 km epicentral distance. For the first time twelve 50-Hz and four 20 Hz GPS observations for seismological study were used and analyzed in Taiwan; a clear benefit was evidenced with regard to the seismic waves features detection, with respect to the 1-Hz GPS data, so that ultra-high rate (> 1-Hz) observations can compensate the sparse coverage of seismic data, provided proper monuments for the GPS permanent stations are realized. Spectra analysis between co-located GPS and strong motion data further suggests that the optimal sampling rate for high-rate GPS Seismology study is 5 Hz. The 2013 Ruisui Taiwan earthquake recorded by the high-rate GPS permanent stations network in Taiwan demonstrates the benefits of GPS Seismology for a moderate size earthquake at a local scale