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Settimi, Alessandro
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- PublicationRestrictedThe COMPLEIK subroutine of the IONORT-ISP system for calculating the non-deviative absorption: A comparison with the ICEPAC formula(2014-01-15)
; ; ; ; ; ; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Zolesi, B.; 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; ; ; ; ; The present paper proposes to discuss the ionospheric absorption, assuming a quasi-flat layered ionospheric medium, with small horizontal gradients. A recent complex eikonal model [Settimi et al., 2013b] is applied, useful to calculate the absorption due to the ionospheric D-layer, which can be approximately characterized by a linearized analytical profile of complex refractive index, covering a short range of heights between h1= 50 km and h2= 90 km. Moreover, Settimi et al. [2013c] have already compared the complex eikonal model for the D-layer with the analytical Chapman’s profile of ionospheric electron density; the corresponding absorption coefficient is more accurate than Rawer’s theory [1976] in the range of middle critical frequencies. Finally, in this paper, the simple complex eikonal equations, in quasi-longitudinal (QL) approximation, for calculating the non-deviative absorption coefficient due to the propagation across the D-layer are encoded into a so called COMPLEIK (COMPLex EIKonal) subroutine of the IONORT (IONOspheric Ray-Tracing) program [Azzarone et al., 2012]. The IONORT program, which simulates the three-dimensional (3-D) ray-tracing for high frequencies (HF) waves in the ionosphere, runs on the assimilative ISP (IRI-SIRMUP-P) discrete model over the Mediterranean area [Pezzopane et al., 2011]. As main outcome of the paper, the simple COMPLEIK algorithm is compared to the more elaborate semi-empirical ICEPAC formula [Stewart, undated], which refers to various phenomenological parameters such as the critical frequency of E-layer. COMPLEIK is reliable just like the ICEPAC, with the advantage of being implemented more directly. Indeed, the complex eikonal model depends just on some parameters of the electron density profile, which are numerically calculable, such as the maximum height.20888 560 - PublicationRestrictedThe effect of collisions in ionogram inversion(2013)
; ; ;Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; The results of this paper demonstrate that the effect of collisions on the group refraction index is small, when the ordinary ray is considered. If, however, in order to improve the performance of a system for automatic interpretation of ionograms, the information contained in ordinary and extraordinary traces is combined, the effect of collisions between the electrons and neutral molecules should be taken into account for the extraordinary ray. The magnitude of these differences is generally very small and must be compared with the resolution in the virtual vertical height of the ionosonde, resolution which is typically of the order of few kilometers.381 35 - 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 AccessThe IONORT-ISP-WC system: inclusion of an electron collision frequency model for the D-layer(2015-04-15)
; ; ; ; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; The IONORT-ISP system (IONOspheric Ray-Tracing – IRI-SIRMUP-PROFILES) was recently developed and tested by comparing the measured oblique ionograms over the radio link between Rome (41.89ºN, 12.48ºE), Italy, and Chania (35.51ºN, 24.02ºE), Greece, with the IONORT-ISP simulated oblique ionograms (Settimi et al., 2013). The present paper describes an upgrade of the system to include: a) electron-neutral collision have been included by using a collision frequency model that consists of a double exponential profile; b) the ISP three dimensional (3-D) model of electron density profile grid has been extended down to the altitude of the D-layer; c) the resolution in latitude and longitude of the ISP 3-D model of electron density profile grid has been increased from 2°x2° to 1°x1°. Based on these updates, a new software tool called IONORT-ISP-WC (WC means with collisions) was developed, and a database of 33 IONORT-ISP-WC synthesized oblique ionograms calculated for single (1-hop paths) and multiple (3-hop paths) ionospheric reflections. The IONORT-ISP-WC simulated oblique ionograms were compared with the IONORT-IRI-WC synthesized oblique ionograms, generated by applying IONORT in conjunction with the International Reference Ionosphere (IRI) 3-D electron density grid, and the observed oblique ionograms over the aforementioned radio link. The results obtained show that (1) during daytime, for the lower ionospheric layers, the traces of the synthesized ionograms are cut away at low frequencies because of HF absorption; (2) during night-time, for the higher ionospheric layers, the traces of the simulated ionograms at low frequencies are not cut off (very little HF absorption); (3) the IONORT-ISP-WC MUF values are more accurate than the IONORT-IRI-WC MUF values.545 327 - PublicationOpen AccessPerformance of electrical spectroscopy using a RESPER probe to measure salinity and water content of concrete and terrestrial soil(2011-09-12)
; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, ItaliaThis report discusses the performance of electrical spectroscopy using a resistivity/ permittivity (RESPER) probe to measure salinity s and volumetric content θW of water in concrete and terrestrial soil. A RESPER probe is an induction device for spectroscopy which performs simultaneous noninvasive measurements of electrical resistivity 1/σ and relative dielectric permittivity εr of a subjacent medium. Numerical simulations show that a RESPER probe can measure σ and ε with inaccuracies below a predefined limit (10%) up to the high frequency band. Conductivity is related to salinity, and dielectric permittivity to volumetric water content using suitably refined theoretical models that are consistent with predictions of the Archie and Topp empirical laws. The better the agreement, the lower the hygroscopic water content and the higher the s; so closer agreement is reached with concrete containing almost no bonded water molecules, provided these are characterized by a high σ. The novelty here is application of a mathematical–physical model to the propagation of measurement errors, based on a sensitivity functions tool. The inaccuracy of salinity (water content) is the ratio (product) between the conductivity (permittivity) inaccuracy, as specified by the probe, and the sensitivity function of the salinity (water content) relative to the conductivity (permittivity), derived from the constitutive equations of the medium. The main result is the model prediction that the lower the inaccuracy of the measurements of s and θW (decreasing by as much as an order of magnitude, from 10% to 1%), the higher the σ; so the inaccuracy for soil is lower. The proposed physical explanation is that water molecules are mostly dispersed as H+ and OH- ions throughout the volume of concrete, but are almost all concentrated as bonded H2O molecules only at the surface of soil.171 292 - PublicationOpen AccessMagnetic anomalies of steel drums: a review of the literature and research results of the INGV(2013-04-19)
; ; ; ;Marchetti, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Sapia, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; The detection and evaluation of the status of disposal sites that contain hazardous waste materials is becoming an increasingly important element in environmental investigations. Close cooperation between the Istituto Nazionale di Geofisica e Vulcanologia (INGV; National Institute of Volcanology and Geophysics) in Rome and the Italian environmental police has resulted in numerous underground investigations of different buried materials. Among the geophysical investigation tools, magnetometry is the most effective, rapid and precise of all of the geophysical methods for localizing buried steel drums. Analysis of magnetic map anomalies can provide a variety of information about buried materials, including extension, distribution and depth, with processing of the acquired magnetic data. This information is also very useful in case of excavations that are aimed at the recovery of hazardous waste. This study determines the most relevant analyses reported in the literature, with modeling of magnetometric methods for environmental applications both theoretically and experimentally. Some studies and research results achieved by the INGV in relation to magnetic anomalies produced by buried steel drums are also reported, as found in field operations and as achieved from test sites.633 367 - 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.447 170 - PublicationOpen AccessOptimal Requirements of a Data Acquisition System for a Quadrupolar PROBE employed in Electrical Spectroscopy(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; ; ; This paper discusses the development and engineering of electrical spectroscopy for simultaneous and non invasive measurement of electrical resistivity and dielectric permittivity. A quadrupolar probe is able to perform measurements on a subsurface with inaccuracies below a fixed limit in a band of low frequencies. The probe should be connected to an appropriate analogical digital converter (ADC) which samples in uniform or in phase and quadrature (IQ) 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 uniform or IQ sampling ADC, are analytically expressed. A large number of numerical simulations prove that the performance of the probe depends 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.416 172 - PublicationRestrictedOn the Divergenceless Property of the Magnetic Induction Field(2013-03-01)
; ; ;Severini, S.; Centro Interforze Studi per le Applicazioni Militari (CISAM), Via Bigattiera Lato Monte 10, San Piero a Grado, 56122 Pisa, Italy ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Maxwell’s equations beautifully describe the electromagnetic fields properties. In what follows we will be interested in giving a new perspective to divergence-free Maxwell’s equations regarding the magnetic induction field: divB=0. To this end we will consider some physical aspects of a system consisting of massive nonrelativistic charged articles, as sources of an electromagnetic field (e.m.) propagating in free space. In particular the link between conservation of total momentum and divergence-free condition for the magnetic induction B field will be deeply investigated.This study presents a new context in which the necessary condition for the divergence-free property of the magnetic induction field in the whole space, known as solenoidality condition, directly comes from the conservation of total momentum for the system, that is, sources and field. This work, in general, leads to results that leave some open questions on the existence, or at least the bservability, of magnetic monopoles, theoretically plausible only under suitable symmetry assumptions as we will show.282 2010 - PublicationOpen AccessAssimilation of autoscaled data and regional and local ionospheric models as input source for a real-time 3-D IRI modeling: additional and planned tests(2011-10-10)
; ; ; ; ; ; ; ; ;Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pignatelli, 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 ;Zolesi, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Cander, Lj. R.; Rutherford Appleton Laboratory, Chilton, OX11 0QX, UK; ; ; ; ; ; ; The joint utilization of autoscaled data such as the F2 peak critical frequency foF2, the propagation factor M(3000)F2 and the electron density profile, coming from two reference ionospheric stations (Rome and Gibilmanna), the regional (SIRMUP) and global (IRI) ionospheric models, can provide a valid tool for obtaining a real-time three-dimensional (3-D) electron density mapping of the ionosphere. Preliminary results of the proposed 3-D model are shown by comparing the vertical electron density profiles given by the model with the ones measured at three testing ionospheric stations (Athens, Roquetes and S.Vito). Mostly at the solar terminator the vertical electron density profile extracted from the proposed 3-D model is more representative of the real conditions of the ionosphere than the electron density profile extracted from the IRI-URSI model. Additional tests are planned for geomagnetically disturbed periods, considering more than two reference ionospheric stations, and by using a new oblique-incidence ionospheric sounding campaign between Rome (41.8° N, 12.5°E) and Chania, Greece (35.7°N, 24.0°E), in order to compare the results from radio path measurements with those obtained by the ray tracing technique applied to the real-time 3D pictures of the ionosphere specified by the new developed tool.296 281