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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Co-design of Security Aware Power System Distribution Architecture as Cyber Physical System

Youssef, Tarek 06 April 2017 (has links)
The modern smart grid would involve deep integration between measurement nodes, communication systems, artificial intelligence, power electronics and distributed resources. On one hand, this type of integration can dramatically improve the grid performance and efficiency, but on the other, it can also introduce new types of vulnerabilities to the grid. To obtain the best performance, while minimizing the risk of vulnerabilities, the physical power system must be designed as a security aware system. In this dissertation, an interoperability and communication framework for microgrid control and Cyber Physical system enhancements is designed and implemented taking into account cyber and physical security aspects. The proposed data-centric interoperability layer provides a common data bus and a resilient control network for seamless integration of distributed energy resources. In addition, a synchronized measurement network and advanced metering infrastructure were developed to provide real-time monitoring for active distribution networks. A hybrid hardware/software testbed environment was developed to represent the smart grid as a cyber-physical system through hardware and software in the loop simulation methods. In addition it provides a flexible interface for remote integration and experimentation of attack scenarios. The work in this dissertation utilizes communication technologies to enhance the performance of the DC microgrids and distribution networks by extending the application of the GPS synchronization to the DC Networks. GPS synchronization allows the operation of distributed DC-DC converters as an interleaved converters system. Along with the GPS synchronization, carrier extraction synchronization technique was developed to improve the system’s security and reliability in the case of GPS signal spoofing or jamming. To improve the integration of the microgrid with the utility system, new synchronization and islanding detection algorithms were developed. The developed algorithms overcome the problem of SCADA and PMU based islanding detection methods such as communication failure and frequency stability. In addition, a real-time energy management system with online optimization was developed to manage the energy resources within the microgrid. The security and privacy were also addressed in both the cyber and physical levels. For the physical design, two techniques were developed to address the physical privacy issues by changing the current and electromagnetic signature. For the cyber level, a security mechanism for IEC 61850 GOOSE messages was developed to address the security shortcomings in the standard.
272

On the Performance Evaluation of High-Speed Transport Protocols

Hillyer, Bridget 01 January 2006 (has links)
As high-speed networks with large bandwidth delay products (BDP) become more common, high-speed transport protocols must be developed that perform well in these contexts. TCP has limitations in high BDP networks. A number of high-speed TCP proposals have emerged, including BIC TCP, High Speed TCP, and H-TCP. XCP is an intraprotocol communication mechanism that promises even greater performance by providing explicit feedback from routers about congestion. It requires changes to routers and end hosts, though, whereas the other experimental protocols only require changes to an end host. We evaluated the performance ofXCP against BIC TCP, High Speed TCP, H-TCP, and . NewReno TCP. We found that in a controlled environment, XCP gave much better performance than the other TCPs. XCP was sensitive to misconfiguration and environmental factors, though, and was more difficult to deploy. More work is required to make XCP more stable. The other TCPs did not perform better than NewReno TCP but show promise, as most performed almost as well as NewReno TCP.
273

Construções de constelações de sinais geometricamente uniformes hiperbólicas / Construct hyperbolic geometrically uniform signal constellations

Pilla, Eliane Cristina Geroli 06 September 2005 (has links)
Orientador: Reginaldo Palazzo Júnior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-18T16:43:26Z (GMT). No. of bitstreams: 1 Pilla_ElianeCristinaGeroli_M.pdf: 2007393 bytes, checksum: 2b95255e6d4fca123c23a039d1a083a5 (MD5) Previous issue date: 2005 / Resumo: O presente trabalho tem como meta principal construir constelações de sinais geometricamente uniformes no plano hiperbólico, visando considerá-las como alfabeto para geração de códigos de espaço de sinais, em particular os códigos de classes laterais generalizados. Para estabelecer estas constelações foi escolhido um conjunto de sinais geometricamente uniforme, constituído pelos centros dos octógonos da tesselação {8, 8}. Depois foi obtido um rotulamento para os elementos do grupo gerador dos conjuntos de sinais geometricamente uniformes em cada classe lateral. Finalmente, a partir do isomorfismo rótulo obtivemos um rotulamento isométrico para os elementos do conjunto de sinais / Abstract: Our goal in this work is to construct hyperbolic geometrically uniform signal constellations (more specifically g-torus) that are able to act as alphabets for ge neration of codes. To obtain these constellations we choose geometrically uniform signal sets consisting of the centers of the p-gons of tessellations of type {p, q}. From these constellations we obtain labelings for the elements of the generator group of the geometrically uniform signal sets in each coset. Finally, by the label isomorphism we obtain an isometric labeling for the elements of the signal set / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica
274

Trajectory Privacy Preservation in Mobile Wireless Sensor Networks

Jin, Xinyu 23 October 2013 (has links)
In recent years, there has been an enormous growth of location-aware devices, such as GPS embedded cell phones, mobile sensors and radio-frequency identification tags. The age of combining sensing, processing and communication in one device, gives rise to a vast number of applications leading to endless possibilities and a realization of mobile Wireless Sensor Network (mWSN) applications. As computing, sensing and communication become more ubiquitous, trajectory privacy becomes a critical piece of information and an important factor for commercial success. While on the move, sensor nodes continuously transmit data streams of sensed values and spatiotemporal information, known as ``trajectory information". If adversaries can intercept this information, they can monitor the trajectory path and capture the location of the source node. This research stems from the recognition that the wide applicability of mWSNs will remain elusive unless a trajectory privacy preservation mechanism is developed. The outcome seeks to lay a firm foundation in the field of trajectory privacy preservation in mWSNs against external and internal trajectory privacy attacks. First, to prevent external attacks, we particularly investigated a context-based trajectory privacy-aware routing protocol to prevent the eavesdropping attack. Traditional shortest-path oriented routing algorithms give adversaries the possibility to locate the target node in a certain area. We designed the novel privacy-aware routing phase and utilized the trajectory dissimilarity between mobile nodes to mislead adversaries about the location where the message started its journey. Second, to detect internal attacks, we developed a software-based attestation solution to detect compromised nodes. We created the dynamic attestation node chain among neighboring nodes to examine the memory checksum of suspicious nodes. The computation time for memory traversal had been improved compared to the previous work. Finally, we revisited the trust issue in trajectory privacy preservation mechanism designs. We used Bayesian game theory to model and analyze cooperative, selfish and malicious nodes' behaviors in trajectory privacy preservation activities.
275

WebSAT: Web-based systems administration tool

Jeong, Juyong 01 January 2005 (has links)
Discusses the development of WebSAT (Web-based systems administration tool), a computer network tool that allows systems administrators to create and delete accounts, disable and enable existing accounts, manage disk space conveniently, monitor the status of all network printers, and monitor network security. The WebSAT application was implemented using PHP, a server-side embedded scripting language, with a MySQL database.
276

Generátor modulovaných signálů / Modulated signal generator

Melša, Ondřej January 2010 (has links)
This project occupies with the creation modulated signal generator in MATLAB. There are explicit basic princips of modulation PSK, M-QAM, princip of system with spread spektrum and princip of access OFDM and MC-CDMA. Next there are explicit basic parametres and possibilities configuration of conversion analog PCI card CompuGen 4302, which serves as D/A convertor of signals created by PC.
277

Les fondements métapsychologiques de la notion d'objet autistique à partir d'une observation / Metapsychological foundations of the concept of autistic object from an observation

Desroches, Elisabeth 27 September 2016 (has links)
L'accompagnement en tant qu'auxiliaire de vie scolaire de Max, adolescent diagnostiqué autiste Asperger, fut le cadre de notre observation et de recherche clinique. Max a l'habitude d'aller toucher les cheveux d'autrui, ce que nous envisageons comme la manipulation d'un objet autistique atypique et une modalité particulière de rencontre de l'autre. À partir des travaux et des références de Francès Tustin, nous proposons une recherche à propos des fondements métapsychologiques de la notion d'objet autistique afin de déterminer quels sont les processus psychiques qui sous-tendent leur apparition. Nous étudions les cheveux en tant qu'éléments corporels symboliques et découvrons leur polysémie. Puis nous comparons la fonction et la manipulation des objets autistiques à celles des objets transitionnels, fétiches et self-objects, ce qui nous permet de penser des modalités spécifiques de relations d'objet. Notre hypothèse de la relation autistique à l'objet envisage l'émergence des objets autistiques en tant que témoins d'une relation à l'autre impossible et évitée, mais néanmoins recherchée et désirée. Cet évitement mènerait à l'intérêt pour un objet matériel. En outre, nous présentons le travail d'élaboration de notre accompagnement et de notre relation. Ainsi, l'élaboration du contre-transfert s'étaye sur une mise en dialogue de la situation d'observation et d'œuvres littéraires. Enfin, nous proposons une extension de la notion d'objet autistique et de la relation autistique à l'objet par une réflexion sur les nouvelles modalités de relation à l'autre que constituent les communications numériques. / The help I provided to Max as a school assistant was our context for the clinical research presented in this thesis. Max is a handicapped teenager diagnosed with Asperger's syndrome. He is used to touch other people's hair, which we consider as an atypical autistic object and a particular mode of meeting others. Based on Francès Tustin's work and research, we offer a study about the metapsychological foundations of the autistic object's concept to define the psychic processes underlying their appearance. We consider hair as a symbolic part of the body and found their polysemy. Then we compare the autistic object's fonction and manipulation with those of transitionnal objects, fetish objects and self-objects, which allows us to think of specific modes of object relations. Our hypothesis about autistic object relations considers the emergence of autistic objects as witnesses of an impossible and avoided relation to another, nevertheless sought and desired. This avoidance would lead to the interest for a material object. Moreover, we present the development of our study, in helping and relationship. Therefore the countertransference elaboration is based on dialogue between our observation situation and literary work. At last, we propose an extension of the autistic object concept and of the autistic object relation by reflecting on the new forms of communication with others, like digital communications.
278

Scalable Cognitive Radio Network Testbed in Real Time

Yu, Kevin Z 01 June 2021 (has links) (PDF)
Modern society places an increasingly high demand on data transmission. Much of that data transmission takes place through communication over the frequency spectrum. The channels on the spectrum are limited resources. Researchers realize that at certain times of day some channels are overloaded, while others are not being fully utilized. A spectrum management system may be beneficial to remedy this efficiency issue. One of the proposed systems, Cognitive Radio Network (CRN), has progressed over the years thanks to studies on a wide range of subjects, including geolocation, data throughput rate, and channel handoff selection algorithm, which provide fundamental support for the spectrum management system. To move CRN technology forward, in this thesis we propose a physical, scalable testbed for some of the extant CRN methodologies. This testbed integrates IEEE standards, FCC guidelines, and other TV band regulations to emulate CRN in real time. With careful component selections, we include sufficient operational functionalities in the system, while at the same time making sure it remains affordable. We evaluate the technical feasibility of the testbed by studying several simple CRN logics. When comparing a system with a selection table implemented to those with naive selection methods, there is more than a 60 percent improvement in the overall performance.
279

Low-Cost UAV Swarm for Real-Time Object Detection Applications

Valdovinos Miranda, Joel 01 June 2022 (has links) (PDF)
With unmanned aerial vehicles (UAVs), also known as drones, becoming readily available and affordable, applications for these devices have grown immensely. One type of application is the use of drones to fly over large areas and detect desired entities. For example, a swarm of drones could detect marine creatures near the surface of the ocean and provide users the location and type of animal found. However, even with the reduction in cost of drone technology, such applications result costly due to the use of custom hardware with built-in advanced capabilities. Therefore, the focus of this thesis is to compile an easily customizable, low-cost drone design with the necessary hardware for autonomous behavior, swarm coordination, and on-board object detection capabilities. Additionally, this thesis outlines the necessary network architecture to handle the interconnection and bandwidth requirements of the drone swarm. The drone on-board system uses a PixHawk 4 flight controller to handle flight mechanics, a Raspberry Pi 4 as a companion computer for general-purpose computing power, and a NVIDIA Jetson Nano Developer Kit to perform object detection in real-time. The implemented network follows the 802.11s standard for multi-hop communications with the HWMP routing protocol. This topology allows drones to forward packets through the network, significantly extending the flight range of the swarm. Our experiments show that the selected hardware and implemented network can provide direct point-to-point communications at a range of up to 1000 feet, with extended range possible through message forwarding. The network also provides sufficient bandwidth for bandwidth intensive data such as live video streams. With an expected flight time of about 17 minutes, the proposed design offers a low-cost drone swarm solution for mid-range aerial surveillance applications.
280

Tangibility and Immateriality: Understanding Consumers' Changing Sense of Touch in the Music Industry

Coduto, Kathryn D. 31 July 2014 (has links)
No description available.

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