• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 21
  • 20
  • 9
  • 5
  • 5
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 69
  • 69
  • 54
  • 29
  • 19
  • 13
  • 13
  • 12
  • 12
  • 11
  • 11
  • 11
  • 9
  • 9
  • 8
  • 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.
21

Datová komunikace v distribučních systémech / Data communication in distribution systems

Sirotný, Miroslav January 2011 (has links)
This project includes a basic overview of concepts as is communication, data communication and distributed to systems. Further focuses on the technology use for remote data collection. Part is dedicated PLC technologies, which use systems for remote data collection. The thesis is also mentioned the concept of quality of electrical energy and standard ČSN EN 50160. The main part is focused on the design, implementation and measurement of the PLC network.
22

Síťová komunikace po napájecím vedení / Power-line network communication

Sláčik, Ján January 2016 (has links)
The master’s thesis is dealing with PLC technology and its modem realization based on several types of standards by using commercially available integrated circuits. This projects also describes fundamentals and prerequisites for building the PLC network fulfilling the European standard CENELEC. The work further describes designed system concept, which serves as the automated system for the appliances connected to an electrical network. Components are selected for implementation and then is introduced concrete solution and implementation power-line network. Within the work are then other parts, that together form a system concept. Work includes the hardware and software implementation and a description of the options implemented system.
23

Noise and Multipath Characteristics of Power Line Communication Channels

Çelebi, Hasan Basri 30 March 2010 (has links)
With the recent developments in technology, information and communication technologies (ICTs) are becoming more widespread and one of the basic building blocks of every humans life. The increasing demand in broadband communication calls for new technologies. Power line communication (PLC) is one of the potential candidates for next generation ICTs. Although communication through power lines has been investigated for a long time, PLC systems were never taken into account seriously because of its harsh communication medium. However, with the development of more robust data transmission schemes, communication over the power lines is becoming a strong alternative technology because of the existence of the infrastructure and the ubiquity of the network. In order to establish reliable communication systems operating on power line networks (PLNs), characteristics of power line channels have to be investigated very carefully. Unpredictable characteristics of PLNs seriously affect the performance of communication systems. Similar to the other communication channels, PLC environment is affected by noise, attenuation, and multipath type of channel distortions. The level of noise in PLNs is much higher than any other type of communication networks. Furthermore, the frequency dependent attenuation characteristics of power lines and multipath stemming from impedance mismatches are the other distortion factors which have to be investigated in order to establish a reliable PLC system. In this thesis, we focus on modeling of noise, frequency dependent attenuation, and multipath characteristics of power line channels within the frequency range between 30kHz and 30MHz.
24

Robust Blind Spectral Estimation in the Presence of Impulsive Noise

Kees, Joel Thomas 07 March 2019 (has links)
Robust nonparametric spectral estimation includes generating an accurate estimate of the Power Spectral Density (PSD) for a given set of data while trying to minimize the bias due to data outliers. Robust nonparametric spectral estimation is applied in the domain of electrical communications and digital signal processing when a PSD estimate of the electromagnetic spectrum is desired (often for the goal of signal detection), and when the spectrum is also contaminated by Impulsive Noise (IN). Power Line Communication (PLC) is an example of a communication environment where IN is a concern because power lines were not designed with the intent to transmit communication signals. There are many different noise models used to statistically model different types of IN, but one popular model that has been used for PLC and various other applications is called the Middleton Class A model, and this model is extensively used in this thesis. The performances of two different nonparametric spectral estimation methods are analyzed in IN: the Welch method and the multitaper method. These estimators work well under the common assumption that the receiver noise is characterized by Additive White Gaussian Noise (AWGN). However, the performance degrades for both of these estimators when they are used for signal detection in IN environments. In this thesis basic robust estimation theory is used to modify the Welch and multitaper methods in order to increase their robustness, and it is shown that the signal detection capabilities in IN is improved when using the modified robust estimators. / Master of Science / One application of blind spectral estimation is blind signal detection. Unlike a car radio, where the radio is specifically designed to receive AM and PM radio waves, sometimes it is useful for a radio to be able to detect the presence of transmitted signals whose characteristics are not known ahead of time. Cognitive radio is one application where this capability is useful. Often signal detection is inhibited by Additive White Gaussian Noise (AWGN). This is analogous to trying to hear a friend speak (signal detection) in a room full of people talking (background AWGN). However, some noise environments are more impulsive in nature. Using the previous analogy, the background noise could be loud banging caused by machinery; the noise will not be as constant as the chatter of the crowd, but it will be much louder. When power lines are used as a medium for electromagnetic communication (instead of just sending power), it is called Power Line Communication (PLC), and PLC is a good example of a system where the noise environment is impulsive. In this thesis, methods used for blind spectral estimation are modified to work reliably (or robustly) for impulsive noise environments.
25

Filtros digitais para a separação de subbandas em sistemas PLC baseados em clustered-OFDM

Schettino, Hugo Viveiros 26 February 2016 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-07T14:12:32Z No. of bitstreams: 1 hugoviveirosschettino.pdf: 1159424 bytes, checksum: 924405f3d1d2d0ad229acb0e08e88be9 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-13T13:15:33Z (GMT) No. of bitstreams: 1 hugoviveirosschettino.pdf: 1159424 bytes, checksum: 924405f3d1d2d0ad229acb0e08e88be9 (MD5) / Made available in DSpace on 2016-07-13T13:15:33Z (GMT). No. of bitstreams: 1 hugoviveirosschettino.pdf: 1159424 bytes, checksum: 924405f3d1d2d0ad229acb0e08e88be9 (MD5) Previous issue date: 2016-02-26 / Este trabalho investiga o uso de filtros digitais de resposta ao impulso finita (finite impulse response - FIR) e de resposta ao impulso infinita (infinite impulse response - IIR) para separar os sinais dos clusters de esquemas de multiplexação por divisão de frequência ortogonal clusterizado (clustered orthogonal frequency division multiplexing - clustered-OFDM), aplicado à sistema de comunicação via rede elétrica (power line communication - PLC). Nesse contexto, introduz-se uma formulação para explicitar a influência do filtro digital no esquema clustered- OFDM. A partir dessa formulação, uma equação que quantifica a vazão em função do uso dos filtros digitais, a qual leva em consideração a relação sinal ruído multicanal, a especificação do filtro e, principalmente, o comprimento dele, é apresentada. Através de simulações computacionais, analisa-se o desempenho do esquema sujeito a um conjunto de filtros digitais previamente selecionados, considerando três cenários: canal corrompido pelo ruído aditivo, gaussiano e branco (additive white Gaussian noise - AWGN), canal PLC indoor corrompido ruído (medido numa residência localizada na cidade de Juiz de Fora, MG) e canal PLC outdoor corrompido pelo ruído (medido numa rede de distribuição de energia elétrica de baixa tensão na cidade de Juiz de Fora, MG). De acordo com os resultados computacionais, dentre os filtros digitais analisados, os filtros digitais Chebychev tipo II, FIR interpolado (interpolated FIR - IFIR) e FIR de fase mínima e equiripple são, de maneira geral, os filtros digitais que proporcionam os melhores benefícios (maior vazão e menor complexidade computacional). Considerando-se a influência da precisão finita nesses três filtros digitais, conclui-se que o filtro digital IIR Chebychev tipo II quantizado proporciona a menor perda de vazão e, portanto, é um filtro bastante adequado para esquemas clustered-OFDM. / This work investigates the use of finite impulse response (FIR) and infinite impulse response (IIR) digital filters to separate the signals belonging distinct clusters in a clustered orthogonal frequency division multiplexing (clustered-OFDM) scheme, when it is applied to power line communication (PLC) system. In this context, we introduce a formulation to take into account the choice of the digital filter for the clustered-OFDM scheme. Based on this formulation, an equation that quantifies the data-rate as a function ofmultichannel signal noise ratio, digital filter design specification and length of the digital filter is presented. Performance analyses based on a previously selected set of digital filters over three scenarios, channel corrupted by additivewhite Gaussian noise (AWGN), indoor PLC channel corrupted by the noise (measured in a residence located in Juiz de Fora city, MG) and outdoor PLC corrupted by the noise (measured in a low voltage distribution network in Juiz de Fora city, MG), are presented. According to numerical results, Chebychev type II, interpolated FIR (IFIR) and equiripple minimum phase FIR digital filters offers the best benefits in terms of less data-rate loss and computer complexity reduction. Considering the influence of the finite precision in these three digital filters, simulation results shows that the quantized Chebychev type II IIR digital filter attains the smallest data-rate loss and, as a consequence, it a very appropriate digital filter for clustered-OFDM schemes.
26

Interactivity in Cybermedia News: An Interview with Journalists in Colombia, Peru, and Ecuador

Barredo Ibáñez, Daniel, Pinto Garzón, Karen, Freundt-Thurne, Úrsula, Medranda Morales, Narcisa 05 1900 (has links)
Interactivity is a factor on which cyber journalism is based and summarizes participation options between a user and the medium, a user with other users, and a user with editors. In this study, we focus on the latter in three countries-Colombia, Peru, and Ecuador-, which have been identified owing to their technological gap and the emerging importance of online communication for their respective societies. Through 35 in-depth interviews with journalists from these countries, we analyzed the concept of interactivity of these professionals and their relationship with users. The results revealed that the journalists positively valued civic contributions as a space for diagnosis, although they do not perceive its informational value, as they relate them to the context of opinions. These results verify the prevalence of journalism as strongly influenced by conventional offline production routines. / Revisión por pares
27

Wearable Systems in Harsh Environments : Realizing New Architectural Concepts

Chedid, Michel January 2010 (has links)
Wearable systems continue to gain new markets by addressing improved performance and lower size, weight and cost. Both civilian and military markets have incorporated wearable technologies to enhance and facilitate user's tasks and activities. A wearable system is a heterogeneous system composed of diverse electronic modules: data processing, input and output modules. The system is constructed to be body-borne and therefore, several constraints are put on wearable systems regarding wearability (size, weight, placement, etc.) and robustness rendering the task of designing wearable systems challenging. In this thesis, an overview of wearable systems was given by discussing definition, technology challenges, market analysis and design methodologies. Main research targeted at network architectures and robustness to environmental stresses and electromagnetic interference (EMI). The network architecture designated the data communication on the intermodule level - topology and infrastructure. A deeper analysis of wearable requirements on the network architecture was made and a new architecture is proposed based on DC power line communication network (DC-PLC). In addition, wired data communication was compared to wireless data communication by introducing statistical communication model and looking at multiple design attributes: power efficiency, scalability, and wearability. The included papers focused on wearable systems related issues including analysis of present situation, environmental and electrical robustness studies, theoretical and computer aided modelling, and experimental testing to demonstrate new wearable architectural concepts. A roadmap was given by examining the past and predicting the future of wearable systems in terms of technology, market, and architecture. However, the roadmap was updated within this thesis to include new market growth figures that proved to be far less than was predicted in 2004. User and application environmental requirements to be applied on future wearable systems were identified. A procedure is presented to address EMI and evaluated solutions in wearable application through modelling and simulation. Environmental robustness and wearability of wearable systems in general, and washability and conductive textile in particular are investigated. A measurement-based methodology to model electrical properties of conductive textile when subjected to washing was given. Employing a wired data communication network was found to be more appropriate for wearable systems than wireless networks when prioritizing power efficiency. The wearability and scalability of the wired networks was enhanced through conductive textile and DC-PLC, respectively. A basic wearable application was built to demonstrate the suitability of DC-PLC communication with conductive textile as infrastructure. The conductive textile based on metal filament showed better mechanical robustness than metal plated conductive textile. A more advanced wearable demonstrator, where DC-PLC network was implemented using transceivers, further strengthened the proposed wearable architecture. Based on the overview, the theoretical, modelling and experimental work, a possible approach of designing wearable systems that met several contradicting requirements was given.
28

Jämförande analys av driftsäkerhet medRTU och PLC / Comparative analysis of the operation safety of the RTU and PLC

Albadri, Rand January 2015 (has links)
Examensarbetet kommer att göra en jämförande analys av driftsäkerhet med trådade signaler till en Remote Terminal Unit (RTU) och en Programmable Logic Controller (PLC) med busstyrning. Rapporten genomfördes som ett uppdrag av Skellefteå Kraft AB för att se om det möjligt att byta till PLC- med busstyrning. Rapporten redogör för grundläggande beskrivning för skillnaden mellan de här två system och kommer att undersöka vilken som är driftsäkrare och lönsammare med hänsyn till krav enligt Svenska Kraftföretagens riktlinjer för dammsäkerhet (Ridas).Med hjälp av kurslitteratur, ABB handboken, internet websidor samt intervjuar med Skellefteå Kraft AB:s personal har arbetets resultat visat att busstyrning med PLC kommer att fungera driftsäkert samt kommer att bli lönsamt jämfört med trådade signaler till RTU. Resultat visat även att det finns ingenting som hindrar att installera busstyrning enligt Ridas men vissa funktioner bör installeras. Rapporten är avgränsat genom att inte ta upp eventuella krav från miljöbalken. / This thesis will make a comparative analysis of the operation safety of the wire connection to Remote Terminal Unit (RTU) and Programmable Logic Controller (PLC) with bus-controller. The report describes the basic description of the difference between these two systems and will explore which is safer and more economic with consideration to qualification according to Swedish energy companies' guidelines for dam safety (Ridas).Through course literature, ABB Bok, internet web sits and interviews with Skellefteå Kraft AB staff the result of this report have been created.The report results prove that PLC with bus-controller will operate operationally safe and profitable compared to wire connection to RTU. Results also showed that there is nothing which prevents to install bus-controller according to RIDAS but certain features should be installed.
29

BTL marketingová komunikace a její význam pro budování značky / BTL marketing communication and its importance for brand building

Bindzarová, Lucie January 2016 (has links)
The topic of the thesis deals with BTL marketing communication and its importance for brand building. The aim is to analyze tools of BTL marketing communication on the Czech market and identify the most effective tools that can be used to build brand in the FMCG environment. The thesis should provide more details about below the line communication and its increase use market positioning. Also identify appropriate tool for building brand image, quality and raising customer awareness. Research, expert interviews and case studies were used to prove the objective of this thesis.
30

Firmware pro řízení systému komunikace po silnoproudém vedení / Firmware for power line communicaiton system

Majer, Dominik January 2019 (has links)
In this diploma thesis it was introduced the issue of power line communication and network architecture design with goal to create own concept of smart house system. Consequently, the necessary communication protocols are designed and described based on the concept. Further is described the implementation of the designs and testing of the realized system under laboratory conditions using the real communication devices. Summary of the achieved results is supported by demonstration of real functionality.

Page generated in 0.1328 seconds