1,722,248 research outputs found
Funzionamento e disabilità delle persone con sindrome di Down: risultati dello studio nazionale.
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ADS-B Anomalies and Intrusions Detection by Sensor Clocks Tracking
No full textAutomatic Dependent Surveillance-Broadcast (ADSB) is an Air Traffic Control system in which aircraft transmit their own information (identity, position, velocity etc.) to ground sensors for surveillance scope. The tracking of the different sensors' clocks by the use of Time Difference of Arrival of ADSB messages is proposed to check the veracity of the position information contained in the ADS-B messages. The method allows detecting possible on board anomalies or the malicious injection of fake messages (intrusion) without the use of the multilateration (or any other) location algorithm. It follows that it does not need the inversion of the location problem (usually strong non-linear and ill-posed), and, contrary to the multilateration, it works also with less than 4 sensors
La sicurezza alimentare. Sviluppi sul tema anche alla luce dell'EXPO 2015
Full text linkIl primo capitolo del lavoro è dedicato alla definizione del concetto di sicurezza alimentare,
chiarendo la differenza di significato per i due termini inglesi che vengono tradotti con la medesima parola italiana “sicurezza”, pur indicando l’uno la sicurezza d’uso, o salubrità (safety), il secondo, invece, il concetto che sarà prevalentemente approfondito nella restante parte del lavoro: la security alimentare, che significa assicurare a ciascun individuo della specie umana una corretta e bilanciata razione alimentare. La trattazione prosegue inquadrando la sicurezza alimentare prima nella cornice degli obiettivi del Millennio e poi dei nuovi Obiettivi di Sviluppo Sostenibile, recentemente adottati all’unanimità il 27 settembre del 2015 dalle Nazioni Unite. Il secondo obiettivo di sviluppo sostenibile recita infatti: porre fine alla fame, raggiungere la sicurezza alimentare e migliorare la nutrizione e promuovere
l'agricoltura sostenibile. Vengono poi illustrate brevemente le principali istituzioni ospitate dall’Italia, che si occupano a vario titolo di sicurezza alimentare. Dal secondo capitolo si entra nel vivo del tema del lavoro individuale, discutendo i cosiddetti paradossi della sicurezza alimentare che, ancora, a distanza di vent’anni dal World Food Summit del
1996, affliggono la popolazione, in particolare dei paesi più poveri, con gravi conseguenze sul piano della salute degli esseri umani, ma anche sul piano della pace e stabilità.
Vengono di seguito introdotti due concetti molto importanti: il tema degli sprechi alimentari ed il ruolo che le tecnologie alimentari possono giocare per la sicurezza alimentare a garanzia dei consumatori. Il terzo capitolo approfondisce le tematiche di EXPO 2015, sintetizzandole e analizzando due delle cosiddette legacy immateriali che l’Esposizione ci ha lasciato, da cui ripartire per raggiungere con maggiore determinazione l’obiettivo Fame Zero. In questo capitolo viene anche affrontato uno dei temi centrali, che cerca di definire un nuovo approccio per la food security e per un’agricoltura sostenibile, alla luce dei potenziali drammatici effetti del cambiamento climatico in atto. Il capitolo conclusivo affronta i temi della Sovranità Alimentare e del Diritto al Cibo e l’importante ruolo della sicurezza alimentare nell’assicurare la pace e la stabilità a livello internazionale. Il lavoro si chiude con un breve richiamo all’importante ruolo giocato dall’Italia nel contesto internazionale discusso.The first chapter of the work is devoted to the definition of the concepts of respectively food
security and food safety, making clear the difference in the meaning of the two English words that are translated with the same Italian word "sicurezza", while indicating the one the safe consumption of food, the second, instead, the concept which will mainly be deepened in the remaining part of the work: food security, which means ensuring every individual of the human species a correct and balanced nutrition. The discussion continues framing the food safety at first inside the Millennium goals and then in the framework of the new Sustainable Development Goals (SDG), unanimously adopted recently on September 27th 2015 by the United Nations. The second SDG affirms, in fact: zero hunger, achieve food security and improve nutrition and promote sustainable agriculture. The main international institutions hosted in Italy, dealing with the different aspects both of food safety and security. From the second chapter we go into the heart of the matter, discussing the so-called food security
paradoxes, that, twenty years on from the World Food Summit of 1996, are still affecting the
population, especially in the poorest countries, with serious consequences to the health of the
people, but also on the peace and stability of these countries. Two important concepts are then introduced: the issue of food waste and the role that food technologies can play to raise the level of food safety ant to protect the consumers. The third chapter debates some of the main themes of EXPO 2015, synthesizing and analyzing two of the so-called immaterial legacies that the Exhibition left us, in order to fight with greater determination to achieve the goal Zero Hunger. This chapter also addresses one of the central themes, which seeks to define a new approach to food security and sustainable agriculture, because of the potential dramatic effects of climate change. The final chapter deals with the issues of food sovereignty and the right to food, and the important role of food security in ensuring peace and stability internationally. The work closes with a brief reference to the important role played by Italy in the international context discussed
Aspetti di sicurezza nell'utilizzo dei sistemi di navigazione
Full text linkI sistemi di navigazione satellitare sono sempre più utilizzati nel settore della geomatica (dal rilevamento, alla georeferenziazione, ai sistemi per la guida dei droni). Questa penetrazione nel mercato, però, non sempre ha tenuto conto dei relativi aspetti di sicurezza e delle conseguenti minacce per l’incolumità dell’uomo
Backward Compatible Physical Layer Protocol Evolution for ADS-B Message Authentication
No full textThe automatic dependent surveillance-broadcast system is a pillar of the future air traffic control system. It is a surveillance system in which air planes transmit their information (identity, position, velocity, etc.) in broadcast to any listener equipped with a receiver. Networks of ADS-B receivers have been installed all over the world, producing a clear traffic awareness for air traffic controllers. For historical reasons, this protocol does not have any authentication/encryption mechanism. The aim of this article is to improve the ADS-B system security by introducing a physical layer protocol modification for the introduction of an authentication scheme. The proposed evolution fully complies with the current standard and exploits the phase modulation to increase the number of bits that can be transmitted with a single packet of data. These additional bits can be used to carry authentication information, making the overall system more secure (and safe). The proposed protocol evolution is developed ensuring backward compatibility and respecting the ICAO and RTCA recommendations; it can be introduced and used together with the present standard in a mixed scenario, allowing a smooth transition from the present protocol to the new one. Protocol performances were evaluated by simulations and, moreover, its feasibility and compliance with recommendations were tested using a software-defined radio (as transmitter) and a laboratory ADS-B receiver
Fully Autonomous Orbit Determination and Synchronization for Satellite Navigation and Communication Systems in Halo Orbits
Full text linkThis paper presents a solution for autonomous orbit determination and time synchronization of spacecraft in Halo orbits around Lagrange points using inter-satellite links. Lagrange points are stable positions in the gravitational field of two large bodies that allow for a sustained presence of a spacecraft in a specific region. However, a challenge in operating at these points is the lack of fixed landmarks for orbit determination. The proposed solution involves using inter-satellite links to perform range and range-rate measurements, allowing for accurate computation of the spacecraft's orbit parameters without the need for any facilities on Earth. Simulations using a fleet of three satellites in Near Rectilinear Halo Orbits around the Earth-Moon Lagrange point, proposed for the Lunar Gateway stations, were conducted to demonstrate the feasibility of the approach. The results show that inter-satellite links can provide reliable and accurate solutions for orbit determination with a DRMS error lower than one meter (90th percentile) and synchronization errors of around one nanosecond. This solution paves the way for a fully autonomous fleet of spacecraft that can be used for observation, telecommunication, and navigation missions
Degarbling technique for low cost ADS-B receivers
No full textOne of the most important parts of the present and future Air Traffic Control system is the Automatic Dependent Surveillance-Broadcast (ADS-B) system [1] [2]; in this system aircraft transmit (with a given periodicity) their position, velocity and identity to equipped aircraft or ground station for surveillance purposes [3]. The on-board navigation system, mainly based on the GPS unit, is used to calculate these information and the Secondary Surveillance Radar transponder is used to broadcast messages containing these information on the common RF channel. Receiving these messages the ATC centres are able to have a traffic awareness.An important limitation of this protocol is that the throughput is limited by a particular interfering problem: the garbling effect (that is the reception of superimposed signals coming from different aircraft). A method to reduce this effect is proposed in this work. The method exploits a multichannel receiver and the Principal Component Analysis and is suitable for implementation in low cost Software Defined Radio. It is also evaluated using real signals varying the Hardware parameters (such as Band, ADC characteristics and Oscillator stability) to identify which Hardware can be adopted for its implementation
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