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Settimi, Alessandro
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- PublicationOpen AccessA method to test HF ray tracing algorithm in the ionosphere by means of the virtual time delay(2011-09-26)
; ; ; ; ; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Azzarone, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Lozito, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; ; ; ; ;Santucci, Sandro; Dipartimento di Fisica, Università dell’’Aquila.It is well known that a 3D ray tracing algorithm furnishes the ray’s coordinates, the three components of the wave vector and the calculated group time delay of the wave along the path. The latter quantity can be compared with the measured group time delay to check the performance of the algorithm. Simulating a perfect reflector at an altitude equal to the virtual height of reflection, the virtual time delay is assumed as a real time delay. For a monotonic electronic density profile we find a very small relative difference between the calculated and the virtual delay for both analytic and numerical 3D electronic density models.21338 603 - PublicationOpen AccessA method to test HF ray tracing algorithm in the ionosphere by means of the virtual time delay(2011-08-13)
; ; ; ; ; ;Azzarone, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Lozito, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; ; It is well known that a 3D ray tracing algorithm furnishes the ray’s coordinates, the three components of the wave vector and the calculated group time delay of the wave along the path. The latter quantity can be compared with the measured group time delay to check the performance of the algorithm. Simulating a perfect reflector at an altitude equal to the virtual height of reflection, the virtual time delay is assumed as a real time delay. For a monotonic electronic density profile we find a very small relative difference between the calculated and the virtual delay for both analytic and numerical 3D electronic density models.21343 549 - PublicationRestrictedA RESPER probe for measurements of RESistivity and PERmittivity(Lambert Academic Publishing (LAP), 2012-05-16)
; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ;Beatrice besson; LAP LAMBERT Academic Publishing GmbH & Co. KG Heinrich-Böcking-Str. 6-8 66121; LAP LAMBERT Academic Publishing GmbH & Co. KG Heinrich-Böcking-Str. 6-8 66121; LAP LAMBERT Academic Publishing GmbH & Co. KG Heinrich-Böcking-Str. 6-8 66121; LAP LAMBERT Academic Publishing GmbH & Co. KG Heinrich-Böcking-Str. 6-8 66121, Saarbrücken, GermanyThe electrical RESistivity and dielectric PERmittivity measuring device (RESPER) for non-invasive investigation of media is an exploiting electrical induction by means of capacitive coupling with media as terrestrial soils and concretes. The device utilizes a four-electrode probe to inject a radio frequency into a medium and register an induced current. Complex transfer impedance can be determined from a ratio between a potential measured across two electrodes, and an induced current flowing in the medium. Electrical parameters of resistivity and permittivity characterizing the medium can be established from the transfer impedance, using inversion formulas that also take into account the geometric ratio and position of the electrodes. The device exploits the in-phase and quadrature under sampling technique which, together with numerical operations performed by a microcontroller, allows the device to attain a required performance. It is possible to execute a number of numerical integrations which, combined with some circuit solutions, can reduce the amplitude and phase errors of the acquired signal. The device can operate at variable frequency, maintaining a suitable under-sampling frequency to fully exploit the analogical-digital acquisition performance both in velocity and dynamic range.162 22 - PublicationOpen AccessInaccuracy assessment for simultaneous measurement of resistivity and permittivity applying sensitivity and transfer function approaches(2010-04)
; ; ; ; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Baskaradas, J. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; The present study proposes a theoretical modeling of simultaneous and noninvasive measurements of electrical resistivity and dielectric permittivity using a quadrupole probe on a subjacent medium. A mathematical-physical model is applied to the propagation of errors in the measurement of resistivity and permittivity based on a sensitivity functions tool. The findings are also compared with results of the classical method of analysis in the frequency domain, which is useful for determining the behavior of zero and pole frequencies in the linear time invariant circuit of the quadrupole. This study underlines that average values of electrical resistivity and dielectric permittivity can be used to estimate complex impedance over various terrains and concretes, especially when they are characterized by low levels of water saturation (content), and are analyzed within a bandwidth ranging only from low to middle frequencies. To meet the design specifications, that ensure satisfactory performances of the probe (inaccuracies of no more than 10%), the forecasts provided by the sensitivity functions approach are discussed in comparison with those foreseen by the transfer functions method (in terms of both the band of frequency f and the measurable range of resistivity rho, or permittivity epsilon).597 164 - PublicationOpen AccessCoherent Control of Stimulated Emission inside one dimensional Photonic Crystals: Strong Coupling regime(InTech - open science, open minds, 2015-04-22)
; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ;Bananej, A.; Laser &Optics Research SchoolThe present book chapter discusses the stimulated emission, in strong coupling regime, of an atom embedded inside a one dimensional (1D) Photonic Band Gap (PBG) cavity which is pumped by two counter-propagating laser beams. Quantum electrodynamics is applied to model the atom-field interaction, by considering the atom as a two level system, the e.m. field as a superposition of normal modes, the coupling in dipole approximation, and the equations of motion in Wigner-Weisskopf and rotating wave approximations. In addition, the Quasi Normal Mode (QNM) approach for an open cavity is adopted, interpreting the local density of states (LDOS) as the local density of probability to excite one QNM of the cavity; and therefore rendering this LDOS dependent on the phase difference of the two laser beams. In this book chapter we demonstrate that the strong coupling regime occurs at high values of the LDOS. In accordance with the results of the literature, the emission probability of the atom decays with an oscillatory behaviour, so that the atomic emission spectrum exhibits two peaks (Rabi splitting). The novelty of this book chapter is that the phase difference of the two laser beams can produce a coherent control of both the oscillations for the atomic emission probability and, as a consequence, of the Rabi splitting in the emission spectrum. Possible criteria to design active delay lines are finally discussed.325 415 - PublicationOpen AccessIL RAY-TRACING NELLA IONOSFERA(2010-11-30)
; ; ; ;Azzarone, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; ; ;Zolesi, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, ItaliaIl pacchetto applicativo “IONORT” per il calcolo del ray-tracing può essere utilizzato dagli utenti che impiegano il sistema operativo Windows. È un programma la cui interfaccia grafica con l’utente è realizzata in MATLAB. In realtà, il programma lancia un eseguibile che integra il sistema d’equazioni differenziali scritto in linguaggio Fortran e ne importa l’output nel programma MATLAB, il quale genera i grafici e altre informazioni sul raggio. A completamento di questa premessa va detto che questo pacchetto, nella sua parte computazionale, è figlio di un programma di Jones e Stephenson del 1975, dal titolo “A versatile three-dimensional ray-tracing computer program for radio waves in the ionosphere”, il quale a sua volta si rifaceva principalmente a un programma di ray-tracing di Dudziak (1961) e di altri ricercatori quali Croft and Gregory (1963), ecc.. Pertanto, come tutti i recenti programmi di ray- tracing, questo è un programma fatto di programmi e non si può non menzionare qui la prima applicazione numerica di ray-tracing di Haeselgrove (1955). Attualmente questi programmi sono stati ottimizzati e adattati alle applicazioni dei radar oltre l’orizzonte - Over The Horizon, OTH – [Coleman, 1998][Nickish, 2008] sfruttando le potenzialità di potenti computer e periferiche per la presentazione e l’utilizzo real-time nel problema delle coordinate registration CR. In ultimo, si precisa che tutti i parametri di input, output e le modalità d’uso del pacchetto applicativo sviluppato saranno forniti nel manuale utente allegato al CD.21400 616 - PublicationOpen AccessOptimal requirements of a data acquisition system for a quadrupolar probe employed in resistivity and permittivity surveys(2010-12)
; ; ; ; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Baskaradas, J. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; This paper discusses the development and engineering of a suitable quadrupolar probe for simultaneous and non invasive surveys of electrical resistivity and dielectric permittivity. The quadrupolar probe is able to perform measurements on a subsurface with inaccuracies below a fixed limit (10%) in a bandwidth of low (LF) frequency (100kHz). The quadrupole should be connected to an appropriate analogical digital converter (ADC) which samples in phase and quadrature (IQ) or in uniform mode. If the probe is characterized by a galvanic contact with the surface, the inaccuracies in the measurement of resistivity and permittivity, due to the IQ or uniform sampling ADC, are analytically expressed. A large number of numerical simulations proves that the performances of the probe depend on the selected sampler and that the IQ is better compared to the uniform mode under the same operating conditions, i.e. bit resolution and medium.447 169 - PublicationOpen AccessDesign and Implementation of an Induction Probe for Simultaneous Measurements of Permittivity and Resistivity(2009-08-08)
; ; ; ; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Baskaradas, J. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; In this paper, we propose a discussion concerning the design and implementation of an induction probe for electrical SPECTROscopy which performs simultaneous and not invasive measurements on the electrical RESistivity ρ and dielectric PERmittivity εr of the terrestrial ground and concretes (SPECTRORESPER probe). In order to design a SPECTRORESPER which measures ρ and εr with inaccuracies below a prefixed limit (10%) in a band of low frequencies (B=100kHz), the probe should be connected to an appropriate analogical digital converter (ADC), which samples in uniform or in phase and quadrature (IQ) mode, otherwise to a lock-in amplifier. We develop a large number of numerical simulations, applying the Mathcad program, which provide the optimization of the height above ground, the electrode-electrode distance and working frequencies minimizing the inaccuracies of the SPECTRORESPER, in galvanic or capacitive contact with terrestrial soils or concretes, of low or high resistivity. As final findings, we underline that the performances of a lock-in amplifier are even better compared to an IQ ADC with high resolution bit, under the same operating conditions. As consequences in the practical applications: if the probe is connected to a system of data acquisition as an uniform or rather an IQ sampler, then it could be commercialized for companies of building and road paving, being employable for analyzing “in situ” only concretes; otherwise, if the data acquisition system is a lock-in amplifier, the marketing would be for companies of geophysical prospecting, involved to analyze “in situ” even terrestrial soils.537 214 - PublicationOpen AccessLinking Quasi-Normal and Natural Modes of an open cavity(2010-08-16)
; ; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Severini, S.; Centro Interforze Studi Applicazioni Militari (CISAM) – Via della Bigattiera 10, 56122 San Piero a Grado, Pisa, Italy; The present paper proposes a comparison between the extinction theorem and the Sturm–Liouville theory approaches for calculating the electromagnetic (e.m.) field inside an optical cavity. We discuss for the first time to the best of our knowledge, in the framework of classical electrodynamics, a simple link between the quasi normal modes (QNMs) and the natural modes (NMs) for one-dimensional (1D), two-sided, open cavities. The QNM eigenfrequencies and eigenfunctions are calculated for a linear Fabry–Pe´rot (FP) cavity. The first-order Born approximation is applied to the same cavity in order to compare the first-order Born approximated and the actual QNM eigenfunctions of the cavity. We demonstrate that the first-order Born approximation for an FP cavity introduces symmetry breaking: in fact, each Born approximated QNM eigenfunction produces values below or above the actual QNM eigenfunction value on the terminal surfaces of the same cavity. Consequently, the two error-functions for an approximated QNM are not equal in proximity to the two terminal surfaces of the cavity.261 175 - PublicationOpen AccessAn in-depth analysis on the Quasi-Longitudinal approximations applied to ionospheric ray-tracing, oblique and vertical sounding, and absorptionFor the phase refraction index of high frequency (HF) waves in the ionospheric medium exists a well-established theory. However, under the Quasi-Longitudinal (QL) conditions, scientific literature presents various formulas that are not equivalent and that, in some cases, give rise to wrong results. In the present study, further consequences of Booker's rule are discussed, illustrating the validity ranges of the above-mentioned approximate formulas; and the different regimes for applying such QL formulas are described, along with the consequences in simulating the ionospheric HF ray-tracing, oblique and vertical sounding, and absorption.
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