1,026 research outputs found

    Unconventional gas: potential energy market impacts in the European Union

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    In the interest of effective policymaking, this report seeks to clarify certain controversies and identify key gaps in the evidence-base relating to unconventional gas. The scope of this report is restricted to the economic impact of unconventional gas on energy markets. As such, it principally addresses such issues as the energy mix, energy prices, supplies, consumption, and trade flows. Whilst this study touches on coal bed methane and tight gas, its predominant focus is on shale gas, which the evidence at this time suggests will be the form of unconventional gas with the most growth potential in the short- to medium-term. This report considers the prospects for the indigenous production of shale gas within the EU-27 Member States. It evaluates the available evidence on resource size, extractive technology, resource access and market access. This report also considers the implications for the EU of large-scale unconventional gas production in other parts of the world. This acknowledges the fact that many changes in the dynamics of energy supply can only be understood in the broader global context. It also acknowledges that the EU is a major importer of energy, and that it is therefore heavily affected by developments in global energy markets that are largely out of its control.JRC.F.3-Energy securit

    Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

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    Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

    Enhancing Trust in Devices and Transactions of the Internet of Things

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    With the rise of the Internet of Things (IoT), billions of smart embedded devices will interact frequently.These interactions will produce billions of transactions.With IoT, users can utilize their phones, home appliances, wearables, or any other wireless embedded device to conduct transactions.For example, a smart car and a parking lot can utilize their sensors to negotiate the fees of a parking spot.The success of IoT applications highly depends on the ability of wireless embedded devices to cope with a large number of transactions.However, these devices face significant constraints in terms of memory, computation, and energy capacity.With our work, we target the challenges of accurately recording IoT transactions from resource-constrained devices. We identify three domain-problems: a) malicious software modification, b) non-repudiation of IoT transactions, and c) inability of IoT transactions to include sensors readings and actuators.The motivation comes from two key factors.First, with Internet connectivity, IoT devices are exposed to cyber-attacks.Internet connectivity makes it possible for malicious users to find ways to connect and modify the software of a device.Second, we need to store transactions from IoT devices that are owned or operated by different stakeholders.The thesis includes three papers. In the first paper, we perform an empirical evaluation of Secure Boot on embedded devices.In the second paper, we propose IoTLogBlock, an architecture to record off-line transactions of IoT devices.In the third paper, we propose TinyEVM, an architecture to execute off-chain smart contracts on IoT devices with an ability to include sensor readings and actuators as part of IoT transactions

    Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

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    Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression

    Design and evaluation of wireless dense networks : application to in-flight entertainment systems

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    Le réseau sans fil est l'un des domaines de réseautage les plus prometteurs avec des caractéristiques uniques qui peuvent fournir la connectivité dans les situations où il est difficile d'utiliser un réseau filaire, ou lorsque la mobilité des nœuds est nécessaire. Cependant, le milieu de travail impose généralement diverses contraintes, où les appareils sans fil font face à différents défis lors du partage des moyens de communication. De plus, le problème s'aggrave avec l'augmentation du nombre de nœuds. Différentes solutions ont été introduites pour faire face aux réseaux très denses. D'autre part, un nœud avec une densité très faible peut créer un problème de connectivité et peut conduire à l'optension de nœuds isolés et non connectes au réseau. La densité d'un réseau est définit en fonction du nombre de nœuds voisins directs au sein de la portée de transmission du nœud. Cependant, nous croyons que ces métriques ne sont pas suffisants et nous proposons une nouvelle mesure qui considère le nombre de voisins directs et la performance du réseau. Ainsi, la réponse du réseau, respectant l'augmentation du nombre de nœuds, est considérée lors du choix du niveau de la densité. Nous avons défini deux termes: l'auto-organisation et l'auto-configuration, qui sont généralement utilisés de façon interchangeable dans la littérature en mettant en relief la différence entre eux. Nous estimons qu'une définition claire de la terminologie peut éliminer beaucoup d'ambiguïté et aider à présenter les concepts de recherche plus clairement. Certaines applications, telles que Ies systèmes "In-Flight Entertainment (IFE)" qui se trouvent à l'intérieur des cabines d'avions, peuveut être considérées comme des systèmes sans fil de haute densité, même si peu de nœuds sont relativement présents. Pour résoudre ce problème, nous proposons une architecture hétérogène de différentes technologies à fin de surmonter les contraintes spécifiques de l'intérieur de la cabine. Chaque technologie vise à résoudre une partie du problème. Nous avons réalisé diverses expérimentations et simulations pour montrer la faisabilité de l'architecture proposée. Nous avons introduit un nouveau protocole d'auto-organisation qui utilise des antennes intelligentes pour aider certains composants du système IFE; à savoir les unités d'affichage et leurs systèmes de commande, à s'identifier les uns les autres sans aucune configuration préliminaire. Le protocole a été conçu et vérifié en utilisant le langage UML, puis, un module de NS2 a été créé pour tester les différents scénarios.Wireless networking is one of the most challenging networking domains with unique features that can provide connectivity in situations where it is difficult to use wired networking, or when ! node mobility is required. However, the working environment us! ually im poses various constrains, where wireless devices face various challenges when sharing the communication media. Furthermore, the problem becomes worse when the number of nodes increase. Different solutions were introduced to cope with highly dense networks. On the other hand, a very low density can create a poor connectivity problem and may lead to have isolated nodes with no connection to the network. It is common to define network density according to the number of direct neighboring nodes within the node transmission range. However, we believe that such metric is not enough. Thus, we propose a new metric that encompasses the number of direct neighbors and the network performance. In this way, the network response, due to the increasing number of nodes, is considered when deciding the density level. Moreover, we defined two terms, self-organization and self-configuration, which are usually used interchangeably in the literature through highlighting the difference ! between them. We believe that having a clear definition for terminology can eliminate a lot of ambiguity and help to present the research concepts more clearly. Some applications, such as In-Flight Entertainment (IFE) systems inside the aircraft cabin, can be considered as wirelessly high dense even if relatively few nodes are present. To solve this problem, we propose a heterogeneous architecture of different technologies to overcome the inherited constrains inside the cabin. Each technology aims at solving a part of the problem. We held various experimentation and simulations to show the feasibility of the proposed architecture

    Self-Reliance for the Internet of Things: Blockchains and Deep Learning on Low-Power IoT Devices

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    The rise of the Internet of Things (IoT) has transformed common embedded devices from isolated objects to interconnected devices, allowing multiple applications for smart cities, smart logistics, and digital health, to name but a few. These Internet-enabled embedded devices have sensors and actuators interacting in the real world. The IoT interactions produce an enormous amount of data typically stored on cloud services due to the resource limitations of IoT devices. These limitations have made IoT applications highly dependent on cloud services. However, cloud services face several challenges, especially in terms of communication, energy, scalability, and transparency regarding their information storage. In this thesis, we study how to enable the next generation of IoT systems with transaction automation and machine learning capabilities with a reduced reliance on cloud communication. To achieve this, we look into architectures and algorithms for data provenance, automation, and machine learning that are conventionally running on powerful high-end devices. We redesign and tailor these architectures and algorithms to low-power IoT, balancing the computational, energy, and memory requirements.The thesis is divided into three parts:Part I presents an overview of the thesis and states four research questions addressed in later chapters.Part II investigates and demonstrates the feasibility of data provenance and transaction automation with blockchains and smart contracts on IoT devices.Part III investigates and demonstrates the feasibility of deep learning on low-power IoT devices.We provide experimental results for all high-level proposed architectures and methods. Our results show that algorithms of high-end cloud nodes can be tailored to IoT devices, and we quantify the main trade-offs in terms of memory, computation, and energy consumption

    Super Grids Conception

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    Cílem bakalářské práce “Super Grids Conception” je poskytnout komplexní náhled na problematiku Super Gridů ve smyslu pozadí, konceptu jako takového, dostupných technologií, dosavadních zkušeností a budoucího vývoje, možných zdrojů elektrické energie a konkrétních konceptů a studií. V úvodu jsou osvětleny důvody vedoucí k potřebě elektrických sítí nové generace – celosvětové snahy snižovat dopad výroby elektrické energie na životní prostředí, rostoucí poptávka po elektrické energii a potřeba integrovat obnovitelné zdroje energie. Možné zdroje elektrické energie jsou diskutovány jak v širším kontextu, tak i ve smyslu současných omezení a budoucího vývoje. V druhé části jsou popsány koncepty Smart Gridu, Super Gridu a SuperSmart Gridu s důrazem na přínosy, základní principy a systémové hledisko. Autor se dále zabývá jen koncepcí Super Gridu. Použití stejnosměrných (HVDC) a střídavých (HVAC) technologií je porovnáno z technického i ekonomického hlediska a z něj vycházející typické použití těchto technologií. Dále je podrobně popsána nejlepší dostupná technologie HVDC systémů – základní principy a konfigurace, popis jednotlivých částí, omezení současných technologií, dosavadní zkušenosti a možný prostor pro další vývoj. Následuje zmínka nových výzev oblasti HVAC technologií ve vztahu k Super Gridům a popis problémů souvisejících s hybridními AC/DC linkami a koridory. V poslední části jsou vysvětleny rozdíly v historickém vývoji a současných postojích v různých částech světa. Zároveň jsou představeny koncepce zvažovaných Super Gridů. Zvláštní prostor je poskytnut vizionářské koncepci vytvořené DESERTEC Foundation a technickoekonomické studii OffshoreGrid.The aim of bachelor’s thesis “Super Grids Conception” is to provide complex overview of Super Grids topic in terms of describing the background, concept itself, available technology, experience and further development, possible energy sources and particular concepts and studies. In the beginning, reasons which lead to need of next-gen electrical grids are identified in global goal to reduce environmental impact of power generation, growing electricity demand and emerging need to integrate renewable energy sources. Possible energy sources of the future are discussed in broader context as well as in sense of current limitations and further development. In second part, concepts of Smart Grids, Super Grids and SuperSmart Grids are described focusing on benefits, basic principles and systemic point of view. The author then elaborates on Super Grids Conception. HVDC and HVAC technologies are compared from technical and economical point of view, resulting typical usage is mentioned. Later a detailed overview of state-of-the-art HVDC systems technology is provided, including basic principles and design, components description, limitations of available technology, practical experience and possible development areas. Challenges in HVAC field towards Super Grids are introduced, as well as the issues related to hybrid AC/DC corridors and lines. In the last part, differences in historical development and present attitude between different parts of the world are explained. Considered Super Grid conceptions are introduced with special aim to visionary DESERTEC Foundation Concept and techno-economic study OffshoreGrid.

    Reliability assessment for low-cost unmanned aerial vehicles

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    University of Minnesota Ph.D. dissertation. November 2014. Major: Aerospace engineering and mechanics. Advisors: Gary J. Balas, Peter J. Seiler. 1 computer file (PDF); viii, 110 pages, appendices A-D.Existing low-cost unmanned aerospace systems are unreliable, and engineers must blend reliability analysis with fault-tolerant control in novel ways. This dissertation introduces the University of Minnesota unmanned aerial vehicle flight research platform, a comprehensive simulation and flight test facility for reliability and fault-tolerance research. An industry-standard reliability assessment technique, the failure modes and effects analysis, is performed for an unmanned aircraft. Particular attention is afforded to the control surface and servo-actuation subsystem. Maintaining effector health is essential for safe flight; failures may lead to loss of control incidents. Failure likelihood, severity, and risk are qualitatively assessed for several effector failure modes. Design changes are recommended to improve aircraft reliability based on this analysis. Most notably, the control surfaces are split, providing independent actuation and dual-redundancy. The simulation models for control surface aerodynamic effects are updated to reflect the split surfaces using a first-principles geometric analysis.The failure modes and effects analysis is extended by using a high-fidelity nonlinear aircraft simulation. A trim state discovery is performed to identify the achievable steady, wings-level flight envelope of the healthy and damaged vehicle. Tolerance of elevator actuator failures is studied using familiar tools from linear systems analysis. This analysis reveals significant inherent performance limitations for candidate adaptive/reconfigurable control algorithms used for the vehicle. Moreover, it demonstrates how these tools can be applied in a design feedback loop to make safety-critical unmanned systems more reliable.Control surface impairments that do occur must be quickly and accurately detected. This dissertation also considers fault detection and identification for an unmanned aerial vehicle using model-based and model-free approaches and applies those algorithms to experimental faulted and unfaulted flight test data. Flight tests are conducted with actuator faults that affect the plant input and sensor faults that affect the vehicle state measurements. A model-based detection strategy is designed and uses robust linear filtering methods to reject exogenous disturbances, e.g. wind, while providing robustness to model variation. A data-driven algorithm is developed to operate exclusively on raw flight test data without physical model knowledge. The fault detection and identification performance of these complementary but different methods is compared. Together, enhanced reliability assessment and multi-pronged fault detection and identification techniques can help to bring about the next generation of reliable low-cost unmanned aircraft
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