477 research outputs found
A Hybrid Space-Airborne Forward-Looking Bistatic Synthetic Aperture Radar for global aircraft navigation
No full textThis paper presents the idea of a hybrid bistatic Synthetic Aperture Radar formed by a spaceborne illumination system and a receiving-only airborne forward-looking Synthetic Aperture Radar (F-SAR). The study aims at identifying and developing new imaging techniques for avoidance, landing, and observation, able to guarantee forward-looking real-time, all-weather, day and night, high geometric and radiometric resolution images. Classic monostatic F-SAR is known to be affected by left/right ambiguity, since terrain targets situated symmetrically about the flight path have the same Doppler history. The proposed hybrid bistatic F-SAR can take advantage of the spaceborne illuminator to improve geometric resolution and avoid image ambiguities. Furthermore, the airborne receiver can be very compact and light-weight thus needing neither radar transmitting chain, nor sophisticated antenna technology. Preliminary system performance is evaluated by calculating the expected geometric resolutions, and results shows that the proposed system improve significantly the image capability of a classic forward-looking SAR
Hybrid Space-Airborne Bistatic Synthetic Aperture Radar for Avoidance, Landing and Observation of Unmanned Aerial Systems
No full textThis paper presents the idea of a hybrid bistatic synthetic aperture radar (SAR) formed by a constellation of spaceborne illuminators and receiving-only airborne forward-looking SARs. The study aims at identifying and developing new imaging techniques for avoidance, landing, and observation, able to guarantee forward-looking real-time, all-weather, day and night, high geometric and radiometric resolution images for Unmanned Airborne Systems (UAS). Nowadays, UAS Navigation is mainly performed with satellite navigation systems (e.g. GPS, Galileo) which offer accurate and reliable navigation data, but no information about the surrounding environment. A vision-based navigation system can greatly improve UAS autonomy with an additional beneficial impact on obstacle avoidance capability. SAR systems have been already experienced on-board aircrafts of different classes. However, such sensors have been only used as remote sensing payloads in side-looking geometry. For navigation purposes a forward looking geometry is preferable, but it has been rarely experienced due to major limitations (left/right ambiguity and poor Doppler resolution) which can be only partially mitigated at the cost of strong complexities. These limitations can be overcome by the proposed space airborne bistatic system provided that specific requirements on the acquisition geometry are satisfied. In addition, the airborne receiver can be much more compact and lightweight, with a reduced power request thus complying with typical UAS requirements. Preliminary feasibility assessment and definition of strawman system concept have been conducted under ESA contract (22499/09/F/MOS) considering UAS vision-based navigation as main application even if further uses, e.g. remote sensing or surveillance, have been envisaged
El Tlacuache Núm. 365 (2009). 365 Año 9 (2009) mayo. El Tlacuache
No full textRubén Jaramillo: las intenciones del crimen por Aura Hernández. - Jaramillo y la disputa el sentido de la vida por Flavio Barbosa. - De campesinos a obreros: una comunidad surgida entre las flores por Rafael Gutiérrez
Innovative forward looking SAR systems for UAV guidance navigation and landing
No full textThe future evolution of the Airspace System includes various manned and unmanned vehicles flying contemporaneously in an unstructured environment, to support civil, commercial and military applications.
During various phases of the flight, it is of paramount importance to offer an advanced “see-understand” system either to the pilot or finalized to autonomous flight and operation. Sensing and Avoid, Emergency control and landing and assistance to navigation are fundamentally based on acquiring and analyzing high geometric and radiometric resolution all-weather day and night images along the flight path of the vehicle.
The conducted studies here presented had the main purpose to reply at this increasing need of the airspace system researching for the most suitable system able to provide an aircraft with a forward looking real time vision. In the study several solutions are proposed, analyzed and simulated by a sophisticated simulation system. All systems are based on SAR technology to provide the aircraft with a system totally independent on the daylight or weather conditions.
The main challenge of the work indeed lies in using a SAR system in a forward looking configuration. In fact, it is well known that in such a configuration a SAR shows the typical limitations of its technology like a dramatic decrease of the Doppler bandwidth, the characteristic left-right ambiguity and also increases the needed image-time thus decreasing the refresh rate.
The new FL SAR systems here proposed aim to solve these problems using new solutions and well tested technologies recombined together in order to overcome or bypass the classical FL SAR problems.
The intermediate systems also presented along the dissertation, point out the main problems we faced with and provide the logic evolution of the ideas path that leaded to the ultimate FL SAR system able to offer a continuous and hi-resolution FL SAR vision
Personnalisation et leadership Le cas du Mouvement Cinq Étoiles
No full textThe article draws a characterisation of the late comer among the Italian populist parties, the Five Star’ Movement, led by the ancient comedian Beppe Grillo. Starting with a definition of what he means by “political personalisation”, the Author first describe this party as a political organisation in which the leader masters all the key areas – notably, communication, rules setting, and resolution of internal conflicts. Then, he argue that the Five Star Movement is a “personalist party”, in which Beppe Grillo embodies a powerful but non-charismatic leader. In the closing section, the Author tries to shed light above the probable evolutions of the party, particularly dealing with its institutionalisation process
Galileo-based space–airborne bistatic SAR for UAS navigation
No full textThis paper presents the idea of a hybrid bistatic Synthetic Aperture Radar (SAR) formed by a constellation of spaceborne illuminators and receiving-only airborne SARs. The study aims at identifying and developing new remote sensing techniques, able to produce forward-looking, real-time, any-weather, day and night, high geometric and radiometric resolution data for Unmanned Airborne Systems (UAS) autonomous navigation, namely obstacle detection and landing. Special emphasis is devoted to potentials and limitations of using Galileo or a Galileo improved constellation as illuminator. Preliminary feasibility assessment and definition of strawman concepts conducted under ESA contract in the framework of future integrated aerospace systems are reported, consisting in performance and trade-off studies of two configurations of the space segment and of two operating modes of the space–airborne bistatic SAR
Un capitolo della fortuna delle "Decades" di Biondo Flavio: da Pio II a Giovanni Albino
No full textL’articolo concentra l’attenzione sul contenuto del ms. München, Bayerische Staatsbibliothek, Clm 11 324, descritto dal catalogo come «Albini Lucani excerpta ex Blondi decadibus». Ma il codice non contiene gli excerpta delle Historiae ab inclinatione Romano rum imperii di Biondo Flavio, bensí una sintesi della Abbreviatio supra Decades Blondi di papa Pio II. L’autore Giovanni Albino Lucano, storiografo e curatore della biblioteca dei re aragonesi di Napoli, nella dedica al re Alfonso II non fa alcuna menzione del testo di Pio II da lui usato. L’epitome offre una curiosa attestazione indiretta della fortuna di Biondo Flavio, il quale intrattenne diverse relazioni con la corte napoletana di Alfonso il Magnanimo.This article focuses on the contents of MS Munich Bayerische Staatsbibliothek, Clm 11324, described in the catalogue as «Albini Lucani excerpta ex Blondi decadibus». But the MS does not contain the excerpts of the ‘Historiae ab inclinatione Romanorum imperii’ of Biondo Flavio, but a summary of the ‘Abbreviatio supra Decades Blondi’ by Pope Pius II. The author, Giovanni Albino Lucano, historian and librarian for the Aragonese kings of Naples, makes no mention in his preface of the work by Pius II which he had used. The epitome is a curious indirect proof of the influence of Biondo Flavio, who had various contacts with the Neapolitan court of Alfonso il Magnanimo
Correction: Muniz-Santos et al. The Influence of Competition Day Loads on the Metabolic and Immune Response of Olympic Female Beach Volleyball Athletes: A Sportomics Analysis. Nutrients 2025, 17, 1924
No full textFlavio Bachini was not included as an author in the original publication [...
Dopo la trincea: Gramsci, “L’Ordine Nuovo” e la rivoluzione italiana
No full textThrough the articles written by Antonio Gramsci during the first year and a half of release of “L’Ordine Nuovo”, you can see the development lines of what the author has established during the World War I on the historical and political analysis of Italian and European society. These ideas deal directly with Factory Council’s doctrine: Gramsci, inspired by the voluntary initia-tives in Turin factories, builds, since the summer of 1919, a revolutionary theory gathered on the role of working-class institutions. The extensive task of the Factory, in a devastated post-war industrial society, forces the political thinker to reshape the traditional functions of the two representative proletarian institutions: Labor Union and Political Party. Only rethinking about how they work, it’s possible to lead to success the revolutionary movement of the most aware Italian workers: from Turin industries can arise the future construction of Italian Soviet repub-lic that, after the victory of the Revolution in all countries, will be melted in international communist society. This theory stands in a particular position between socialist thinkers of that period, not only towards Reformists or Unitarians Maximalists, but also towards elements of the Communist faction that breaks up with the PSI during national congress of Livorno (Janu-ary 1921) to create a new revolutionary Party
Spaceborne-Airborne Bistatic Radar for UAS Navigation Purpouses: Preliminary Analysis and Strawman System Identification
No full textA novel navigation system for Unmanned Airborne System (UAS) based on bistatic Synthetic Aperture Radar (SAR) is built on spaceborne radar transmitters and airborne receivers, the latter mounted in a forward-looking geometry.
UASs can be categorized either accordingly to the type of the mission, or on the basis of altitude/endurance/range performance, or depending on maximum take-off weight (MTOW), on propulsion technology, etc.
Two preliminary strawman system configurations, characterized by different performance levels and complexities, can be envisaged, all building of an upgrade of Galileo constellation. In the first case, the additional payload to be embarked on Galileo satellites has a medium impact on the platform, whereas such impact is kept at a more reasonable level for the second option
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