Civiltà della Campania. Anno II, n. 2 (febbraio-marzo 1975)

A. II, n. 2 (febbraio-marzo 1975): M. Parrilli, All’Unesco Ravello e Castellabate, P. 3 ; L’anno santo in Campania, P. 7; B. Gatta, Videre Petrum, P. 8; B. Lucrezi, Gli itinerari sacri, P. 12 ; Il Duomo di Salerno: novecento anni di fede e storia », P. 24 ; R. Causa, Santuari nel Nocerino, P. 26 ; G. Giordano, Pacem in maribus, P. 32 ; R. Virtuoso, L’ambiente e il ruolo del turismo, P. 40 ; S. Pavia, I centri storici, P. 32 ; R. Di Stefano, Villa Campolieto, P. 48 ; R. De Simone, Feste popolari, P. 56 ; E. Corsi, II riassetto di Ischia, P. 60 ; C. Nazzaro, Rosmarino col pomodoro, P. 65 ; G. Doria, Il napoletano che cammina, P. 66 ; M. Stefanile, Raffaele Viviani, P. 68 ; A. Fratta, Amedeo Maiuri: una vita per l’archeologia, P. 80 ; E. Fiore, Gli Incontri del Cinema, P. 86 ; G. Blasi, Petrosino l’antipadrino, P. 90 ; I. Santoro, Il mistero di Velia di, P. 93 ; R. Senatore, La rinascita del Borgo Scacciaventi di, P. 97 ; P. Andria, Salerno: S. Pietro a Corte, P. 100 ; U. Abundo, Amalfi sempre di, P. 102 ; V. Gramignazzi Serrone, S. Agata dei Goti, P. 106 ; Attività congressuali in Campania, P. 108 ; Notiziario, P. 10

Civiltà della Campania. Anno II, n. 3 (agosto-ottobre 1975)

A. II, n.3 (agosto-ottobre 1975): Il messaggio dell’Assessore Emilio de Feo, P. 3 ; M. Parrilli, Continuità nel turismo regionale, P. 3 ; Napoli nei secoli, P. 5 ; G. Galasso, Tumulti ed elezioni del ’600, P. 6 ; N. Cilento, Nella città medioevale, P. 18 ; B. Gatta, Capri tra Napoleone e Murat, P. 24 ; R. Causa, Gioacchino Toma a Napoli, P. 30 ; A. Assante, Napoli e il suo porto, P. 34 ; G. Grimaldi, Messaggio di fede dell’Anno Santo, P. 40 ; R. Vlad, Musica all’aperto, P. 50 ; M. Stefanile, Viaggio nella storia di Amalfi, P. 52 ; D. Rea, Mappa minore, P. 60 ; M. Prisco , Incontro con la Badia, P. 68 ; P. Amos e A. Gambardella, Il villaggio di Albori, P. 74 ; R. Virtuoso, Giovanni Cuomo ritorna tra i giovani, P. 76 ; V. Panebianco, Il turismo venuto dalla storia, P. 80 ; A.P. Carbone, Le grotte di Pertosa, P. 84 ; F. de Ciuceis, Il mare di Caserta, P. 88 ; E. Tirone, Riti settennali a Guardia Sanframondi, P. 92 ; F. Calabro, Turismo e cultura a Capri, P. 98 ; F. de Ciuceis, Settembre al Borgo, P. 102 ; I. Santoro, Teggiano citta museo, P. 104 ; Notiziario, P. 108

Translating Microscopic Molecular Motion into Macroscopic Body Motion: Reversible Self-Reshaping in the Solid State Transition of an Organic Crystal

The amplification of microscopic molecular motions so as to produce a controlled macroscopic body effect is the main challenge in the development of molecular mechanical devices. That amplification requires the coherent and ordered movement of each molecule of a whole macroscopic set, such as that taking place in a single-crystal-to-single-crystal transition. Actually, single-crystal-to-single-crystal transitions in molecular crystals can produce a variety of mechanical effects potentially useful in the development of smart materials. A challenging issue in these dynamic crystals, propedeutic to many possible applications in devices, is the gaining of a strict control over the mechanical effects associated with the transition. Here we report an example in which the control of the mechanical effects was successfully obtained. The compound studied undergoes a reversible single-crystal-to-single-crystal transition at 71 °C, from a planar stacked to a herringbone type packing. To this transition, a reversible macroscopic self-reshaping of the crystal is associated. Depending on the morphology, the crystal specimen undergoes a reversible longitudinal expansion of about 20% or a reversible transverse expansion of 20%, the other two dimensions of the crystal specimen being substantially unchanged. The amount of the macroscopic reshaping effect (20%) fully matches the relative variation of the sole unit cell parameter that changes during the transition (from 8.139 to 9.666 Å) in a sort of scale-invariant process. This represents striking evidence of controlled translation of sub-nanometer molecular motions up to the macroscopic scale of body motion

Cooperative navigation and visual tracking with passive ranging for UAV flight in GNSS-challenging environments

This paper discusses an approach conceived to improve navigation performance of small Unmanned Aerial Vehicles (UAVs) in GNSS-challenging environments by exploiting cooperation with other aircraft flying in better GNSS coverage conditions. Cooperation is realized by exchanging navigation data (i.e., GNSS observables when available) and exploiting a monocular camera system for relative vision-based tracking. Cooperative measurements are used within an Extended Kalman Filter, developing a solution potentially ready for real-time applications. The visual algorithm exploits both Deep Learning-based detectors and standard machine vision techniques to provide not only accurate line-of-sight but also distance estimates, and it is designed to deal with targets placed both above and below the horizon. The two algorithmic blocks are integrated in a closed loop fashion since navigation estimates are used in feedback to support visual processing. An experimental flight test campaign is carried out using two quadcopters to assess attainable navigation performance in terms of attitude and positioning. Results compare filter performance when using line-of-sight only with the case of using line-of-sight and ranging measurements altogether. They demonstrate that reliability and integrity of visual algorithms are good enough for the navigation filter needs, and that metric positioning error is achieved within GNSS-challenging areas by using the proposed cooperative strategy. The added value of range estimation strongly depends on the formation geometry and the GNSS coverage conditions

Closed loop integration of air-to-air visual measurements for cooperative UAV navigation in GNSS challenging environments

This paper discusses the integration of air-to-air visual measurements within a cooperative multi-vehicle architecture conceived to improve navigation performance of small Unmanned Aerial Vehicles in GNSS-challenging environments. The key concept is to exploit cooperation with other aircraft flying under better GNSS coverage conditions by exchanging navigation data and using a monocular camera system for relative sensing purposes. Specifically, accurate line of sight, obtained using Deep Learning-based detectors and local image analysis, are complemented with distance information achieved through an innovative shape-based passive ranging approach accounting for both the target attitude and its position in the field of view. Camera-based measurements are combined with the estimates generated by the other onboard sensors, within a customized Extended Kalman Filter in a closed loop fashion, since navigation estimates are used in feedback as hints for visual processing. An experimental flight test campaign is carried out using two quadcopters. A comparison between filter performance achievable as a function of the specific set of available information sources, i.e., bearing-only vs. line of sight and ranging, is carried out. Results show that the trade-off between correct, false, and missed detections, as well as the passive ranging accuracy allow the filter ensuring metric-level positioning error within GNSS-challenging areas. The added value of using both bearing and range measurements strongly depends on the formation geometry and the GNSS coverage conditions and can be predicted thanks to the “generalized dilution of precision”

Detection and tracking of non-cooperative flying obstacles using low SWaP radar and optical sensors: an experimental analysis

Improvements in low altitude, non-cooperative sense and avoid are of major interest for collision hazard mitigation within the UTM/UAM/U-Space framework. In this regard, the sensing architecture must be carefully designed so that its detection and tracking performance is suitable for timely and reliable conflict assessment, while respecting size, weight, power and costs constraints, which are particularly strict for small aerial vehicles. Within this framework, an experimental assessment of non-cooperative sensing solutions based on a lightweight radar and a visual camera, respectively, is presented in this paper. Visual detections are obtained by using a Deep Learning-based neural network, while raw detections produced by the radar are first filtered based on Doppler information to remove ground clutter, and then clustered by means of a centroiding approach. The resulting detection sets are used to generate tentative and firm tracks using customized Kalman filtering techniques. Following a research plan that foresees data gathering with incremental complexity, ground-to-air tests have been carried out using a small UAV as flying intruder, and Carrier-Phase Differential GNSS to get a reference solution and assess visual-based and radar-based detection and tracking performance. Results achieved by standalone radar and visual sensing solutions clearly highlight the potential of sensor fusion strategies to take advantage of their complementary characteristics

Short π‐Stacking in N‐Rich Ionic Aromatic Compounds

Reaction of N-rich conjugated bis(3,4-diamino-1,2,4-triazole)s with dilute hydrochloric acid affords bis(3,4-diamino-1,2,4-triazol-2-ium)chlorides. These compounds form layered structures in which planar layers of molecules are parallelly stacked. The π-stacking distance of the layers is relatively short, as compared with all-carbon-containing aromatic compounds, ranging between 3.00 and 3.22 Å at 173 K, and several contacts shorter than the sum of van der Waals radii are observed in the crystal structures. The features of the crystal structures are discussed in terms of the high nitrogen content of the compounds and of the H-bonding patterns. Periodic ab initio theoretical calculations of the crystal structures have allowed decomposing the lattice energy into various contributions in order to put up the relevance of van der Waals interactions for the π-stacking. In particular, it is found that van der Waals interactions account for about 10% of the total lattice energy and about 50% of the stacking energy (interlayer energy)

Experimental analysis of Radar/Optical track-to-track fusion for non-cooperative Sense and Avoid

In the framework of non-cooperative Sense and Avoid solutions, major attention is reserved to the design of sensing strategies which can enable fast and reliable identification of possible near collision threats, by exploiting passive or active exteroceptive sensors. To overcome the limits of standalone technological architectures and provide more accurate tracking solutions, which can be used to improve conflict detection and thus better support avoidance strategies, data fusion approaches can be considered. Hence, this work proposes a radar/visual fusion method based on the track-to-track fusion approach. The strategy is tested on data gathered during ground-to-air experimental flight tests involving a small UAV commanded to fly near collision approach geometries with respect to a multi-sensor setup placed on the ground. Results collected analyzing three different encounters show that the fusion solution allows retrieving meter and sub-degree level accuracies in the intruder range and bearing estimation, respectively, while ensuring declaration ranges of about 500 meters

Onboard and External Magnetic Bias Estimation for UAS through CDGNSS/Visual Cooperative Navigation

This paper describes a calibration technique aimed at combined estimation of onboard and external magnetic disturbances for small Unmanned Aerial Systems (UAS). In particular, the objective is to estimate the onboard horizontal bias components and the external magnetic declination, thus improving heading estimation accuracy. This result is important to support flight autonomy, even in environments characterized by significant magnetic disturbances. Moreover, in general, more accurate attitude estimates provide benefits for georeferencing and mapping applications. The approach exploits cooperation with one or more “deputy” UAVs and combines drone-to-drone carrier phase differential GNSS and visual measurements to attain magnetic-independent attitude information. Specifically, visual and GNSS information is acquired at different heading angles, and bias estimation is modelled as a non-linear least squares problem solved by means of the Levenberg–Marquardt method. An analytical error budget is derived to predict the achievable accuracy. The method is then demonstrated in flight using two customized quadrotors. A pointing analysis based on ground and airborne control points demonstrates that the calibrated heading estimate allows obtaining an angular error below 1°, thus resulting in a substantial improvement against the use of either the non-calibrated magnetic heading or the multi-sensor-based solution of the DJI onboard navigation filter, which determine angular errors of the order of several degrees

Ground-to-air experimental assessment of low SWaP radar-optical fusion strategies for low altitude Sense and Avoid

The future of UAS operations requires adequate and efficient Sense and Avoid strategies to ensure their safe and secure integration in both controlled and uncontrolled airspace. To make onboard implementation of these strategies feasible, research must focus on the development of sensing and tracking solutions, taking size, weight and power (SWaP) constraints as well as the challenging scenarios characterizing low altitude operations, into account. In this framework, visual cameras and low SWaP radars are among the most popular sensing choices. Hence, exploiting such sensing solutions, this paper proposes both single and multi-sensor detection and tracking approaches and compares their performance. Specifically, the developed techniques are tested on data retrieved during ground-to-air tests which involve a small UAV flying near collision geometries, starting from a range of about 550 m. Different tracking strategies are considered including standalone visual, standalone radar, and fused radar-visual. Concerning intruder detection, several visual-based techniques are investigated based on machine learning, morphological filtering and template matching. Radar detections are filtered and centroided with ad hoc algorithms. While in clear air conditions comparable declaration ranges, larger than 500 m, are provided by all the tested approaches, results show the advantages of using a fused strategy to attain sub-degree angular and angular rate tracking accuracy coupled with the highly accurate range and range rate, around 2 m and 1 m/s, respectively, typical of radars. Conflict detection performance is proven to also benefit from the use of a fused strategy in terms of smaller errors in the estimation of the distance at closest point of approach