6,111 research outputs found

    Urbanised forested landscape: Urbanisation, timber extraction and forest care on the Vișeu Valley, northern Romania

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    By looking at urbanisation processes from the vantage point of the forest, and the ways in which it both constitutes our living space while having been separated from the bounded space of the urban in modern history, the thesis asks: How can we (re)imagine urbanisation beyond the limits of the urban? How can a feminine line of thinking engage with the forest beyond the capitalist-colonial paradigm and its extractive project? and How can we “think with care” (Puig de la Bellacasa 2017) towards the forest as an inhabitant of our common world, instead of perpetuating the image of the forest as a space outside the delimited boundaries of the city? Through a case study research, introducing the Vișeu Valley in northern Romania as both a site engaged in the circulation of the global timber flow, a part of what Brenner and Schmid (2014) name “planetary urbanisation”, where the extractive logging operations beginning in the late XVIIIth century have constructed it as an extractive landscape, and a more than human landscape inhabited by a multitude of beings (animal, plant, and human) the thesis argues towards the importance of forest care and indigenous knowledge in landscape management understood as a trans-generational transmission of knowledge, that is interdependent with the persistence of the landscape as such. Having a trans-scalar approach, the thesis investigates the ways in which the extractive projects of the capitalist-colonial paradigm have and still are shaping forested landscapes across the globe in order to situate the case as part of a planetary forest landscape and the contemporary debates it is engaged in. By engaging with emerging paradigms within the fields of plant communication, forestry, legal scholarship and landscape urbanism that present trees and forests as intelligent beings, and look at urbanisation as a way of inhabiting the landscape in both indigenous and modern cultures, the thesis argues towards viewing forested landscapes as more than human living spaces. Thinking urbanisation through the case of the Vișeu Valley’s urbanised forested landscape, the thesis aligns with alternate ways of viewing urbanisation as co-habitation with more than human beings, particularly those emerging from interdisciplinary research in the Amazon river basin (Tavares 2017, Heckenberger 2012) and, in light of emerging discourses on the rights of nature, proposes an expanded concept of planetary citizenship, to include non-human personhood

    Bildung in der digitalen Transformation

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    Die Coronapandemie und der durch sie erzwungene zeitweise Übergang von Präsenz- zu Distanzlehre haben die Digitalisierung des Bildungswesens enorm vorangetrieben. Noch deutlicher als vorher traten dabei positive wie negative Aspekte dieser Entwicklung zum Vorschein. Während den Hochschulen der Wechsel mit vergleichsweise geringen Reibungsverlusten gelang, offenbarten sich diese an Schulen weitaus deutlicher. Trotz aller Widrigkeiten erscheint eines klar: Die zeitweisen Veränderungen werden Nachwirkungen zeigen. Eine völlige Rückkehr zum Status quo ante ist kaum noch vorstellbar. Zwei Fragen bestimmen vor diesem Hintergrund die Doppelgesichtigkeit des Themas der 29. Jahrestagung der Gesellschaft für Medien in der Wissenschaft (GMW). Erstens: Wie ‚funktioniert‘ Bildung in der sich derzeit ereignenden digitalen Transformation und welche Herausforderungen gibt es? Und zweitens: Befindet sich möglicherweise Bildung selbst in der Transformation? Beiträge zu diesen und weiteren Fragen vereint der vorliegende Tagungsband

    Efficient instance and hypothesis space revision in Meta-Interpretive Learning

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    Inductive Logic Programming (ILP) is a form of Machine Learning. The goal of ILP is to induce hypotheses, as logic programs, that generalise training examples. ILP is characterised by a high expressivity, generalisation ability and interpretability. Meta-Interpretive Learning (MIL) is a state-of-the-art sub-field of ILP. However, current MIL approaches have limited efficiency: the sample and learning complexity respectively are polynomial and exponential in the number of clauses. My thesis is that improvements over the sample and learning complexity can be achieved in MIL through instance and hypothesis space revision. Specifically, we investigate 1) methods that revise the instance space, 2) methods that revise the hypothesis space and 3) methods that revise both the instance and the hypothesis spaces for achieving more efficient MIL. First, we introduce a method for building training sets with active learning in Bayesian MIL. Instances are selected maximising the entropy. We demonstrate this method can reduce the sample complexity and supports efficient learning of agent strategies. Second, we introduce a new method for revising the MIL hypothesis space with predicate invention. Our method generates predicates bottom-up from the background knowledge related to the training examples. We demonstrate this method is complete and can reduce the learning and sample complexity. Finally, we introduce a new MIL system called MIGO for learning optimal two-player game strategies. MIGO learns from playing: its training sets are built from the sequence of actions it chooses. Moreover, MIGO revises its hypothesis space with Dependent Learning: it first solves simpler tasks and can reuse any learned solution for solving more complex tasks. We demonstrate MIGO significantly outperforms both classical and deep reinforcement learning. The methods presented in this thesis open exciting perspectives for efficiently learning theories with MIL in a wide range of applications including robotics, modelling of agent strategies and game playing.Open Acces

    'Exarcheia doesn't exist': Authenticity, Resistance and Archival Politics in Athens

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    My thesis investigates the ways people, materialities and urban spaces interact to form affective ecologies and produce historicity. It focuses on the neighbourhood of Exarcheia, Athens’ contested political topography par excellence, known for its production of radical politics of discontent and resistance to state oppression and eoliberal capitalism. Embracing Exarcheia’s controversial status within Greek vernacular, media and state discourses, this thesis aims to unpick the neighbourhoods’ socio-spatial assemblage imbued with affect and formed through the numerous (mis)understandings and (mis)interpretations rooted in its turbulent political history. Drawing on theory on urban spaces, affect, hauntology and archival politics, I argue for Exarcheia as an unwavering archival space composed of affective chronotopes – (in)tangible loci that defy space and temporality. I posit that the interwoven narratives and materialities emerging in my fieldwork are persistently – and perhaps obsessively – reiterating themselves and remaining imprinted on the neighbourhood’s landscape as an incessant reminder of violent histories that the state often seeks to erase and forget. Through this analysis, I contribute to understandings of place as a primary ethnographic ‘object’ and the ways in which place forms complex interactions and relationships with social actors, shapes their subjectivities, retains and bestows their memories and senses of historicity

    The Adirondack Chronology

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    The Adirondack Chronology is intended to be a useful resource for researchers and others interested in the Adirondacks and Adirondack history.https://digitalworks.union.edu/arlpublications/1000/thumbnail.jp

    Oberflächenemittierende Laser mit vertikaler Kavität (VCSELs) und VCSEL-Arrays für Kommunikation und Sensorik

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    Future generations of optical wireless communication and sensing systems require compact, low-cost, reliable, and highly efficient light sources capable of transmitting modulated beams across free space at gigabit per second (Gbps) data rates and pulsed beams with sub-nanosecond rise and fall times. The infrared vertical cavity surface emitting laser (VCSEL) is exactly one such light source. Fifth generation (5G) systems promise to connect billions of people and trillions of Internet of Things gadgets and sensors at 1 to beyond 20 Gbps via newly auctioned millimeter wave (30 GHz to 300 GHz) spectral bands. By circa 2030 sixth generation (6G) systems envision vast broadband capacity with zero latency – enabling real-time virtual and mixed realities, human-machine interfaces, autonomous vehicles, and much more. The 6G technology adds terahertz wave emitters including infrared VCSELs and VCSEL arrays to vastly increase data rates, boost energy and spectral efficiency, and take advantage of available and unregulated spectral bands. I design, fabricate, and test new experimental VCSEL diodes and novel two-dimensional (2D) VCSEL diode arrays. I study the physics and performance trade-offs of VCSEL light emitters aimed at 5G and 6G optical wireless communication and sensing applications. Via in-house computer modeling and simulation programs, I design VCSEL epitaxial structures – composed of nanometer-thick aluminum-gallium-arsenide, indium-gallium arsenide, and gallium-arsenide-phosphide layers – with peak target emission wavelengths of 940 and 980 nanometers. A commercial foundry grows my experimental VCSEL epitaxial wafers by metal-organic vapor phase epitaxy on 3-inch diameter gallium-arsenide substrates. In my university cleanroom, I fabricate my VCSELs as quarter wafer test pieces using a new VCSEL Array 2018 mask set which contains single VCSELs, and several variations of novel 2D electrically parallel triple (3-element), septuple (7-element), and novemdecuple (19-element) geometric device designs. My fabricated devices feature high frequency, coplanar ground-signal-ground metal contact pads, and top-epitaxial-surface emission. I perform all device tests in my university laser diode laboratory via direct, on-wafer electrical probing under computer control, starting with continuous wave light output power-current-voltage sweeps via a calibrated photodiode-integrating sphere and variable current source. For emission spectra and small-signal frequency response measurements, I collect the emitted VCSEL light with a standard OM1 multiple mode optical fiber (MMF) – connected to either an optical spectrum analyzer or a photoreceiver. For on-wafer data transmission tests across OM1 MMF patch cords, I modulate my VCSELs with nonreturn to zero, pseudorandom bit patterns in the form of 2-level pulse amplitude modulation. I achieve record combinations of optical output power, bandwidth, and efficiency for my large oxide aperture diameter (larger than 20 micrometers) VCSELs and for my VCSEL arrays. For example, I demonstrate 200 milliwatts of optical output power, a bandwidth of 18 GHz, and a wall plug efficiency of 35 percent with a 19-element VCSEL array. I set several records for error free data transmission, for example, 40 Gbps for my triple and septuple VCSEL arrays and 25 Gbps for my novemdecuple VCSEL arrays, well beyond the previous record of 10 Gbps. My work is the first to investigate trade-offs in the highly nontrivial physics of VCSEL arrays aimed at high power and high bandwidth arrays for free space data transmission – producing new guiding principles for further device optimization and product development.Zukünftige Generationen optischer drahtloser Kommunikations- und Sensorsysteme erfordern kompakte, kostengünstige, zuverlässige und hocheffiziente Lichtquellen, die modulierte Strahlen mit Datenraten von Gigabit pro Sekunde (Gbps) und gepulste Strahlen mit Anstieg- und Abfallzeiten im Sub-Nanosekundenbereich über den freien Raum übertragen können. Infrarote, oberflächenemittierende Laser mit vertikaler Kavität (VCSEL) sind genau eine solche Lichtquelle. Systeme der fünften Generation (5G) versprechen, Milliarden von Menschen und Billionen von Geräten und Sensoren für das Internet der Dinge mit 1 bis über 20 Gbps über neu versteigerte Millimeterwellen-Spektralbänder (30 GHz bis 300 GHz) zu verbinden. Bis etwa 2030 sehen Systeme der sechsten Generation (6G) eine enorme Breitbandkapazität ohne Latenzzeit vor – sie ermöglichen virtuelle und gemischte Realitäten in Echtzeit, Mensch-Maschine-Schnittstellen, autonome Fahrzeuge und vieles mehr. Die 6G-Technologie fügt Terahertz-Wellensender hinzu, einschließlich Infrarot-VCSELs und VCSEL-Arrays, um die Datenraten signifikant zu erhöhen, die Energie- und Spektraleffizienz zu steigern und die verfügbaren und noch unregulierten Spektralbänder zu nutzen. In der vorliegenden Arbeit werden neue experimentelle VCSEL-Dioden und neuartige zweidimensionale (2D) VCSEL-Diodenarrays entworfen, hergestellt und getestet. Die Physik der VCSEL-Lichtemittern, welche auf 5G- und 6G-optische drahtlose Kommunikations- und Sensoranwendungen ausgerichtet sind, wird untersucht und Performance-Tradeoffs für die angedachten Anwendungen werden identifiziert und analysiert. Über hauseigene Computermodellierungs- und Simulationsprogramme wurden epitaktische VCSEL-Strukturen – bestehend aus nanometerdicken Aluminium-Gallium-Arsenid-, Indium-Gallium-Arsenid- und Gallium-Arsenid-Phosphid-Schichten – mit Peak-Zielemissionswellenlängen von 940 und 980 Nanometern entworfen. Ein kommerzieller Hersteller hat die experimentellen VCSEL-Epitaxiewafer durch metallorganische Gasphasenepitaxie auf Gallium-Arsenid-Substraten mit einem Durchmesser von 3 Zoll gewachsen. In einem Reinraum an der Universität wurden die VCSELs als Viertelwafer-Teststücke mit einem neuen VCSEL Array 2018-Maskensatz gefertigt, der einzelne VCSELs und mehrere Variationen von neuartigen elektrisch parallelen 2D-Tripel- (3-Element), Septuple- (7-Element) und Novemdecuple- (19-Elemente) Strukturdesigns enthält. Bei den prozessierten Strukturen handelt es sich um Top-Emitter mit hochfrequenzkompatiblen koplanare Masse-Signal-Masse-Metallkontaktpads. Alle Device-Tests wurden computergesteuert in einem universitären Laserdiodenlabor durch direktes elektrisches On-Wafer Probing durchgeführt, beginnend mit Dauerstrich-Lichtausgangsleistung-Strom-Spannungs-Sweeps über eine kalibrierte Photodioden-Integrationskugel und eine variable Stromquelle. Für Emissionsspektren und Kleinsignal-Frequenzgangmessungen wurde das emittierte VCSEL-Licht mit einer standardmäßigen OM1-Multimode-Glasfaser (MMF) eingesammelt – verbunden mit einem optischen Spektrumanalysator oder einem Fotoempfänger. Für On-Wafer-Datenübertragungstests über OM1-MMF-Patchkabel wurden die VCSELs mit pseudozufälligen Bitmustern im Non-Return-To-Zero Format mit 2-Level-Pulsamplitudenmodulation moduliert. In dieser Arbeit werden bisher unerreichte Kombinationen von optischer Ausgangsleistung, Bandbreite und Effizienz für VCSEL und VCSEL-Arrays mit großer Oxid-Apertur (größer als 20 Mikrometer) demonstriert. Beispielsweise werden 200 Milliwatt optische Ausgangsleistung, eine Bandbreite von 18 GHz und eine Konversionseffizienz elektrischer zu optischer Leistung von 35 Prozent mit einem 19-Element-VCSEL-Array erreicht. Zudem werden mehrere Rekorde für fehlerfreie Datenübertragung aufgestellt, zum Beispiel 40 Gbps für Triple- und Septuple-VCSEL-Arrays und 25 Gbps für Novemdecuple-VCSEL-Arrays, weit über den bisherigen Stand der Technik von 10 Gbps hinaus. Diese Arbeit ist die erste, die Trade-Offs in der hochgradig nichttrivialen Physik von VCSEL-Arrays untersucht, die auf Arrays mit hoher Leistung und hoher Bandbreite für die Datenübertragung im freien Raum abzielen – und damit neue Leitprinzipien für die weitere Bauelementoptimierung und Produktentwicklung schafft.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, Bauelement

    Espacios Educativos Innovadores y Sostenibles. Avanzando hacia los ODS.

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    La tesis doctoral “Espacios educativos innovadores y sostenibles”, defendida, por compendio de artículos, en la Universidad Miguel Hernández de Elche, España, corrobora que el diseño y distribución de los espacios educativos facilita la transformación hacia metodologías innovadoras, está relacionado con la salud y bienestar de los usuarios y puede disminuir los gastos de arrastre de los edificios, promoviendo una educación económica responsable. Este es un estudio multidisciplinar que aúna geografía, arquitectura, educación y neurociencias bajo el prisma del medio ambiente. Se trata de marcar el camino hacia una educación integral e innovadora, comprometida con la Agenda 2030 y las necesidades de la sociedad del siglo XXI. Esta investigación contribuye al logro de metas de numerosos ODS, por ejemplo, relacionados con salud y bienestar -ODS 3-, con una educación de calidad -ODS 4-, sensibilizando a la administración educativa sobre la importancia de que los edificios eduquen al alumnado en eficiencia energética y no contaminante y promuevan una educación económica responsable -ODS 7, 9, 11, 12, 13; empleando metodologías de Aprendizaje y Servicio que aumentan las posibilidades de empleabilidad y ayudan a reducir desigualdades -ODS 8 y 10-; con ideas sobre innovación en infraestructuras y tecnologías de la información y comunicación -ODS 9- necesarias en todo momento pero muy especialmente después de la COVID 19; Finalmente, para la puesta en marcha de nuevos diseños y estrategias constructivas y de distribución de espacios educativos, se hace necesario generar alianzas y promover la participación entre centros, administraciones, educadores y destinatarios del proceso -ODS17-. En el estudio se ha empleado una metodología de Investigación Acción Participativa que ha permitido detectar necesidades reales de los usuarios de Institutos de Educación Secundaria Públicos en la Comunidad Valenciana. Poniendo de manifiesto la importancia de divulgar las conclusiones con el fin de sensibilizar a diseñadores y planificadores (estudios de arquitectura y Administración Educativa) de centros educativos. Si bien se van incorporando mejoras, todavía se detecta una brecha entre las recomendaciones de guías e incluso normativa y la realidad de los espacios construidos. En muchas ocasiones estas disonancias no son debidas a falta de inversión financiera, sino a escasa comunicación e insuficiente conocimiento de los programas educativos y actividades que tendrán lugar en los espacios, con la corresponsabilidad de la propia Administración Educativa. Los espacios educativos deberían ser modelo de prácticas sostenibles. El estudio propone espacios sostenibles, fáciles de entender bajo el acrónimo “TICMOTECAS”, que pretende hacer referencia a lugares bien dotados de connectividad (TIC), con MObiliario móvil (flexible y versátil), espacio en el que se cuida y facilita la TEmperatura, los Colores y la Acústica. Estas características, unidas a la luz, ventilación y vistas a naturaleza posibilitan una fusión que nos permite calificar los espacios como SOSTENIBLES, insistiendo en la versión actual de “sostenible” como algo que cubre un triple objetivo, es decir, que aúna los intereses de lo social (participación, empatía, educación), lo económico (gastos de mantenimiento, diseño vanguardista) y lo medioambiental (salud física y psicológica, neuroarquitectura, neuroeducación). Es necesaria una evaluación y seguimiento de los nuevos espacios, tanto si se ajusta a las cada vez más frecuentes, aulas creativas, aulas innovadoras, aulas TECH, aulas LAB o Future Classroom Labs, como si se trata de la ampliación o construcción de un IES Nuevo desde su la fase de proyecto base. Se concluye que sin duda las metodologías y los espacios se complementan, pero la investigación va más allá del ámbito de pedagogías emergentes y llama a estudios de arquitectura y laboratorios de neurocientíficos a co-crear junto con los educadores. Este equipo de investigación multidisciplinar entiende que la educación no es responsabilidad única de proyectos educativos

    Site Trouble: Asianness and Blackness in Contemporary Cultural Production

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    This project explores the relationships of Asianness and Blackness in racialized geographies. Three onscreen spaces organize my inquiry: the Asian-owned convenience store, the college campus, and the freeway. My argument elucidates the structures—racial, carceral, and spatial—that form the possibilities for popular onscreen racial representation. In the first chapter, this project takes up the convenience store’s mise-en-scène to route my exploration of Black-Korean conflict, reading Do the Right Thing (1989), the novel Native Speaker, the TV series Kim’s Convenience (2016-2021), and the 2017 film Gook, as well as the documentary A Love Song for Latasha (2019). I present a theorization of Asianness that turns from binary media in/visibility discourses and centers itself on Asian American and Black feminist visions of flourishing. The second chapter analyzes the space of the college campus through the TV series Dear White People (2016-2021) and Grown-ish (2018-present), addressing the seriality of racial structures through student activism and protest. In this chapter I intervene in serial narrative studies and television studies by insisting that contemporary narrative seriality be understood as underpinned by racial logics. In my final chapter I move to the freeway through Karen Tei Yamashita’s novel Tropic of Orange and the 1997 film Strawberry Fields, exploring the Asian American feminist road narrative. In this chapter I theorize Asianness as racial infrastructure capable of both transmitting and blocking the force of white supremacy and conclude by locating fugitive ways of being in racial geographies. Ultimately, my research contends that opacity, refusal, being-otherwise, and experimental form are essential to shaping an Asian American feminist politics in solidarity with Black liberation.Doctor of Philosoph

    Estudo do IPFS como protocolo de distribuição de conteúdos em redes veiculares

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    Over the last few years, vehicular ad-hoc networks (VANETs) have been the focus of great progress due to the interest in autonomous vehicles and in distributing content not only between vehicles, but also to the Cloud. Performing a download/upload to/from a vehicle typically requires the existence of a cellular connection, but the costs associated with mobile data transfers in hundreds or thousands of vehicles quickly become prohibitive. A VANET allows the costs to be several orders of magnitude lower - while keeping the same large volumes of data - because it is strongly based in the communication between vehicles (nodes of the network) and the infrastructure. The InterPlanetary File System (IPFS) is a protocol for storing and distributing content, where information is addressed by its content, instead of its location. It was created in 2014 and it seeks to connect all computing devices with the same system of files, comparable to a BitTorrent swarm exchanging Git objects. It has been tested and deployed in wired networks, but never in an environment where nodes have intermittent connectivity, such as a VANET. This work focuses on understanding IPFS, how/if it can be applied to the vehicular network context, and comparing it with other content distribution protocols. In this dissertation, IPFS has been tested in a small and controlled network to understand its working applicability to VANETs. Issues such as neighbor discoverability times and poor hashing performance have been addressed. To compare IPFS with other protocols (such as Veniam’s proprietary solution or BitTorrent) in a relevant way and in a large scale, an emulation platform was created. The tests in this emulator were performed in different times of the day, with a variable number of files and file sizes. Emulated results show that IPFS is on par with Veniam’s custom V2V protocol built specifically for V2V, and greatly outperforms BitTorrent regarding neighbor discoverability and data transfers. An analysis of IPFS’ performance in a real scenario was also conducted, using a subset of STCP’s vehicular network in Oporto, with the support of Veniam. Results from these tests show that IPFS can be used as a content dissemination protocol, showing it is up to the challenge provided by a constantly changing network topology, and achieving throughputs up to 2.8 MB/s, values similar or in some cases even better than Veniam’s proprietary solution.Nos últimos anos, as redes veiculares (VANETs) têm sido o foco de grandes avanços devido ao interesse em veículos autónomos e em distribuir conteúdos, não só entre veículos mas também para a "nuvem" (Cloud). Tipicamente, fazer um download/upload de/para um veículo exige a utilização de uma ligação celular (SIM), mas os custos associados a fazer transferências com dados móveis em centenas ou milhares de veículos rapidamente se tornam proibitivos. Uma VANET permite que estes custos sejam consideravelmente inferiores - mantendo o mesmo volume de dados - pois é fortemente baseada na comunicação entre veículos (nós da rede) e a infraestrutura. O InterPlanetary File System (IPFS - "sistema de ficheiros interplanetário") é um protocolo de armazenamento e distribuição de conteúdos, onde a informação é endereçada pelo conteúdo, em vez da sua localização. Foi criado em 2014 e tem como objetivo ligar todos os dispositivos de computação num só sistema de ficheiros, comparável a um swarm BitTorrent a trocar objetos Git. Já foi testado e usado em redes com fios, mas nunca num ambiente onde os nós têm conetividade intermitente, tal como numa VANET. Este trabalho tem como foco perceber o IPFS, como/se pode ser aplicado ao contexto de rede veicular e compará-lo a outros protocolos de distribuição de conteúdos. Numa primeira fase o IPFS foi testado numa pequena rede controlada, de forma a perceber a sua aplicabilidade às VANETs, e resolver os seus primeiros problemas como os tempos elevados de descoberta de vizinhos e o fraco desempenho de hashing. De modo a poder comparar o IPFS com outros protocolos (tais como a solução proprietária da Veniam ou o BitTorrent) de forma relevante e em grande escala, foi criada uma plataforma de emulação. Os testes neste emulador foram efetuados usando registos de mobilidade e conetividade veicular de alturas diferentes de um dia, com um número variável de ficheiros e tamanhos de ficheiros. Os resultados destes testes mostram que o IPFS está a par do protocolo V2V da Veniam (desenvolvido especificamente para V2V e VANETs), e que o IPFS é significativamente melhor que o BitTorrent no que toca ao tempo de descoberta de vizinhos e transferência de informação. Uma análise do desempenho do IPFS em cenário real também foi efetuada, usando um pequeno conjunto de nós da rede veicular da STCP no Porto, com o apoio da Veniam. Os resultados destes testes demonstram que o IPFS pode ser usado como protocolo de disseminação de conteúdos numa VANET, mostrando-se adequado a uma topologia constantemente sob alteração, e alcançando débitos até 2.8 MB/s, valores parecidos ou nalguns casos superiores aos do protocolo proprietário da Veniam.Mestrado em Engenharia de Computadores e Telemátic
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