833 resultados para power line communication


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Dissertação de Mestrado apresentado ao Instituto de Contabilidade e Administração do Porto para a obtenção do grau de Mestre em Marketing Digital, sob orientação da Mestre Inês Veiga Pereira “Esta versão contém as críticas e sugestões dos elementos do júri”

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Adaptive filter is a primary method to filter Electrocardiogram (ECG), because it does not need the signal statistical characteristics. In this paper, an adaptive filtering technique for denoising the ECG based on Genetic Algorithm (GA) tuned Sign-Data Least Mean Square (SD-LMS) algorithm is proposed. This technique minimizes the mean-squared error between the primary input, which is a noisy ECG, and a reference input which can be either noise that is correlated in some way with the noise in the primary input or a signal that is correlated only with ECG in the primary input. Noise is used as the reference signal in this work. The algorithm was applied to the records from the MIT -BIH Arrhythmia database for removing the baseline wander and 60Hz power line interference. The proposed algorithm gave an average signal to noise ratio improvement of 10.75 dB for baseline wander and 24.26 dB for power line interference which is better than the previous reported works

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In a general way, in an electric power utility the current transformers (CT) are used to measurement and protection of transmission lines (TL) 1 The Power Line Carriers systems (PLC) are used for communication between electrical substations and transmission line protection. However, with the increasing use of optical fiber to communication (due mainly to its high data transmission rate and low signal-noise relation) this application loses potentiality. Therefore, other functions must be defined to equipments that are still in using, one of them is detecting faults (short-circuits) and transmission lines insulator strings damages 2. The purpose of this paper is to verify the possibility of using the path to the ground offered by the CTs instead of capacitive couplings / capacitive potential transformers to detect damaged insulators, since the current transformers are always present in all transmission lines (TL's) bays. To this a comparison between this new proposal and the PLC previous proposed system 2 is shown, evaluating the economical and technical points of view. ©2010 IEEE.

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Building energy meter network, based on per-appliance monitoring system, willbe an important part of the Advanced Metering Infrastructure. Two key issues exist for designing such networks. One is the network structure to be used. The other is the implementation of the network structure on a large amount of small low power devices, and the maintenance of high quality communication when the devices have electric connection with high voltage AC line. The recent advancement of low-power wireless communication makes itself the right candidate for house and building energy network. Among all kinds of wireless solutions, the low speed but highly reliable 802.15.4 radio has been chosen in this design. While many network-layer solutions have been provided on top of 802.15.4, an IPv6 based method is used in this design. 6LOWPAN is the particular protocol which adapts IP on low power personal network radio. In order to extend the network into building area without, a specific network layer routing mechanism-RPL, is included in this design. The fundamental unit of the building energy monitoring system is a smart wall plug. It is consisted of an electricity energy meter, a RF communication module and a low power CPU. The real challenge for designing such a device is its network firmware. In this design, IPv6 is implemented through Contiki operation system. Customize hardware driver and meter application program have been developed on top of the Contiki OS. Some experiments have been done, in order to prove the network ability of this system.

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The relation between residential magnetic field exposure from power lines and mortality from neurodegenerative conditions was analyzed among 4.7 million persons of the Swiss National Cohort (linking mortality and census data), covering the period 2000-2005. Cox proportional hazard models were used to analyze the relation of living in the proximity of 220-380 kV power lines and the risk of death from neurodegenerative diseases, with adjustment for a range of potential confounders. Overall, the adjusted hazard ratio for Alzheimer's disease in persons living within 50 m of a 220-380 kV power line was 1.24 (95% confidence interval (CI): 0.80, 1.92) compared with persons who lived at a distance of 600 m or more. There was a dose-response relation with respect to years of residence in the immediate vicinity of power lines and Alzheimer's disease: Persons living at least 5 years within 50 m had an adjusted hazard ratio of 1.51 (95% CI: 0.91, 2.51), increasing to 1.78 (95% CI: 1.07, 2.96) with at least 10 years and to 2.00 (95% CI: 1.21, 3.33) with at least 15 years. The pattern was similar for senile dementia. There was little evidence for an increased risk of amyotrophic lateral sclerosis, Parkinson's disease, or multiple sclerosis.

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Esta tese examina a comunicação on-line não-formal entre os professores universitários e seus alunos e, também, os grupos virtuais criados pelos alunos. No referencial teórico documentou-se subtemas fundamentais para a formação do raciocínio central do trabalho. Teve-se como objeto de pesquisa a pergunta o uso da comunicação on-line de modo não-formal entre professores e alunos complementa o ensino/aprendizagem no curso superior? . Este trabalho abre espaço para que novas investigações sejam realizadas, pois as constatações verificadas na pesquisa ofereceram dados importantes para entender as necessidades que levam os alunos ao uso das tecnologias de comunicação on-line para interagirem com seus colegas de classe e com seus professores. Esses motivos ficaram claramente especificados, ao longo do estudo, como complemento e contribuição na melhoria do ensino/aprendizagem dos alunos além de formalizar a comunicação on-line como um diálogo pedagógico entre professores e alunos. O estudo foi qualitativo e quantitativo e teve como técnica de pesquisa um levantamento de dados realizado em uma amostra de oportunidade/conveniência. A análise dos dados levantados permitiu verificar que o uso da comunicação on-line auxilia no complemento do ensino como reforço às aulas presenciais, e possibilita a aprendizagem aos alunos do curso superior, além de contribuir para um diálogo pedagógico ajudando os professores e os alunos na relação após as aulas.(AU)

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Esta tese examina a comunicação on-line não-formal entre os professores universitários e seus alunos e, também, os grupos virtuais criados pelos alunos. No referencial teórico documentou-se subtemas fundamentais para a formação do raciocínio central do trabalho. Teve-se como objeto de pesquisa a pergunta o uso da comunicação on-line de modo não-formal entre professores e alunos complementa o ensino/aprendizagem no curso superior? . Este trabalho abre espaço para que novas investigações sejam realizadas, pois as constatações verificadas na pesquisa ofereceram dados importantes para entender as necessidades que levam os alunos ao uso das tecnologias de comunicação on-line para interagirem com seus colegas de classe e com seus professores. Esses motivos ficaram claramente especificados, ao longo do estudo, como complemento e contribuição na melhoria do ensino/aprendizagem dos alunos além de formalizar a comunicação on-line como um diálogo pedagógico entre professores e alunos. O estudo foi qualitativo e quantitativo e teve como técnica de pesquisa um levantamento de dados realizado em uma amostra de oportunidade/conveniência. A análise dos dados levantados permitiu verificar que o uso da comunicação on-line auxilia no complemento do ensino como reforço às aulas presenciais, e possibilita a aprendizagem aos alunos do curso superior, além de contribuir para um diálogo pedagógico ajudando os professores e os alunos na relação após as aulas.(AU)

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Esta tese examina a comunicação on-line não-formal entre os professores universitários e seus alunos e, também, os grupos virtuais criados pelos alunos. No referencial teórico documentou-se subtemas fundamentais para a formação do raciocínio central do trabalho. Teve-se como objeto de pesquisa a pergunta o uso da comunicação on-line de modo não-formal entre professores e alunos complementa o ensino/aprendizagem no curso superior? . Este trabalho abre espaço para que novas investigações sejam realizadas, pois as constatações verificadas na pesquisa ofereceram dados importantes para entender as necessidades que levam os alunos ao uso das tecnologias de comunicação on-line para interagirem com seus colegas de classe e com seus professores. Esses motivos ficaram claramente especificados, ao longo do estudo, como complemento e contribuição na melhoria do ensino/aprendizagem dos alunos além de formalizar a comunicação on-line como um diálogo pedagógico entre professores e alunos. O estudo foi qualitativo e quantitativo e teve como técnica de pesquisa um levantamento de dados realizado em uma amostra de oportunidade/conveniência. A análise dos dados levantados permitiu verificar que o uso da comunicação on-line auxilia no complemento do ensino como reforço às aulas presenciais, e possibilita a aprendizagem aos alunos do curso superior, além de contribuir para um diálogo pedagógico ajudando os professores e os alunos na relação após as aulas.(AU)

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A MEMS, silicon based device with a cantilever oscillationsand an integrated magnet is presented for magnetic to electrical transduction. The cantilever structure can be configured either as an energy harvester to harvest power from an AC power line or as an AC current sensor. The positioning of the transducer with respect to the AC conductor is critical in both scenarios. For the energy scavenger, correct positioning is required to optimize the harvested power. For the current sensor, it is necessary to optimise the sensitivity of the sensor. This paper considers the effect of the relative position of the transducer with respect to the wire on the resulting electromagnetic forces and torques driving the device. It is shown here that the magnetic torque acting on a cantilever beam with an integrated magnet and in the vicinity of an alternating electromagnetic field is a very significant driver of the cantilever oscillations.

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The concept of a substantive integrator is introduced as a method for integrated resource and environmental management as a means to assimilate different resource values at the operational or field level. A substantive integrator is a strategic management tool for integrating multiple uses into coprorate management regimes that traditionally manage for single values. Wildlife habitat management is presented as a substantive integrator for managing vegetation on electric utility power line corridors. A case study from northern British Columbia provides an example of wildlife habitat management as a means to integrate other resource values such as aesthetics, access and subsistence along British Columbia Hydro and Power Authority's transmission rights-of-way.

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Purpose – This paper compares the experiential consumption values that motivate consumer choice to purchase online for both male and female purchasers and non-purchasers. Design/methodology/approach – Using the theory of consumption value the study examines gendered perceptions of the functional, social and conditional value of using a virtual consumption setting for purchasing. Data was collected through an online survey and analysed using multiple discriminant analysis to determine meaningful differences between male and female purchasers and non-purchasers. Findings – The findings show that male online purchasers are discriminated from female purchasers by social value and from male non-purchasers by conditional value. Female purchasers are discriminated from male purchasers by functional value and from female non-purchasers by social value. Female non-purchasers are discriminated from female purchasers by conditional value. Male non-purchasers are discriminated from male purchasers by functional and social value. Research limitations/implications – Limitations include using an Internet survey and an Australian sample which may impact the generalisability of the findings to a wider population of Internet users. Future research should involve replication of the study in a country more or less developed in terms of gender composition of internet users to extend the generalisability of the findings. Additionally, researchers should examine whether other dimensions of consumption value,such as social influence through on- and off-line communication networks, may influence consumer choice to purchase online. Practical implications – The study provides practical implications for marketers to leverage consumption values that influence male and female consumers’ choice to purchase online and then drive their behaviour online through integrated marketing campaigns that involve both on- and offline strategies. Originality/value – The research makes an original contribution to the consumer behaviour literature as to date, no research has been found that undertakes such a comprehensive gender-based comparison of the perceived value of using a virtual consumption setting for purchasing.

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Computer vision is much more than a technique to sense and recover environmental information from an UAV. It should play a main role regarding UAVs’ functionality because of the big amount of information that can be extracted, its possible uses and applications, and its natural connection to human driven tasks, taking into account that vision is our main interface to world understanding. Our current research’s focus lays on the development of techniques that allow UAVs to maneuver in spaces using visual information as their main input source. This task involves the creation of techniques that allow an UAV to maneuver towards features of interest whenever a GPS signal is not reliable or sufficient, e.g. when signal dropouts occur (which usually happens in urban areas, when flying through terrestrial urban canyons or when operating on remote planetary bodies), or when tracking or inspecting visual targets—including moving ones—without knowing their exact UMT coordinates. This paper also investigates visual serving control techniques that use velocity and position of suitable image features to compute the references for flight control. This paper aims to give a global view of the main aspects related to the research field of computer vision for UAVs, clustered in four main active research lines: visual serving and control, stereo-based visual navigation, image processing algorithms for detection and tracking, and visual SLAM. Finally, the results of applying these techniques in several applications are presented and discussed: this study will encompass power line inspection, mobile target tracking, stereo distance estimation, mapping and positioning.

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Inspection aircraft equipped with cameras and other sensors are routinely used for asset location, inspection, monitoring and hazard identification of oil-gas pipelines, roads, bridges and power transmission grids. This paper is concerned with automated flight of fixed-wing inspection aircraft to track approximately linear infrastructure. We propose a guidance law approach that seeks to maintain aircraft trajectories with desirable position and orientation properties relative to the infrastructure under inspection. Furthermore, this paper also proposes the use of an adaptive maneuver selection approach, in which maneuver primitives are adaptively selected to improve the aircraft’s attitude behaviour. We employ an integrated design methodology particularly suited for an automated inspection aircraft. Simulation studies using full nonlinear semi-coupled six degree-of-freedom equations of motion are used to illustrate the effectiveness of the proposed guidance and adaptive maneuver selection approaches in realistic flight conditions. Experimental flight test results are given to demonstrate the performance of the design.