Fabio Mendonca

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Papers by Fabio Mendonca

Design and power production of small-scale wind turbines

2017 International Conference in Energy and Sustainability in Small Developing Economies (ES2DE), 2017

Wind is one of the most used renewable energy sources for general applications due to its power a... more Wind is one of the most used renewable energy sources for general applications due to its power availability. There are several studies that use wind energy in small-scale systems, however few analyse the lower then 10000 Reynolds number range and the usual approach consists in apply a commercial turbine, or adapt one from other system, to a commercial generator, providing low efficiency system. This paper uses Schmitz theory to design wind turbines in the centimetre scale based on three airfoils, BW3, E62 and S1223. A wind tunnel was used to determine the power coefficient and maximum power transfer, with a small generator. However, the problem with the use of wind energy in urban areas is the variability of the available power since most of the time the wind speed is very low. Therefore, this work includes a study on remote monitoring using a wind turbine to feed a wireless sensor node and a vertical axis wind turbine was used to compare the systems behaviour. The results demonstrate these systems are capable to feed the load and charge a battery even with very low average wind speed.

Combination of Deep and Shallow Networks for Cyclic Alternating Patterns Detection

2018 13th APCA International Conference on Control and Soft Computing (CONTROLO), 2018

The cyclic alternating pattern can be seen as an electroencephalogram marker of sleep instability... more The cyclic alternating pattern can be seen as an electroencephalogram marker of sleep instability. This pattern consists of alternations between activation and quiescent phases. An automatic cyclic alternating pattern detection method is proposed, having the advantage, over other previously proposed methods, of being featureless. Therefore, there is no need to handcraft features and employ a feature selection procedure. A Deep Auto Encoder is used for automatic feature extraction and classification of the activation phases. A shallow Artificial Neural Network is then employed for cyclic alternating pattern classification using the output of the Deep Auto Encoder. These two-cascaded networks are connected by a memory buffer. Both networks are optimized using a heuristic approach and Kolmogorov's Mapping theorem. A public database with 14 subjects is used to test the methods. For the activation phase classification, a 2 seconds raw EEG is used as an input of the Deep Auto Encoder. For the cyclic alternating pattern classifier, the whole memory buffer is used as input. The accuracy of activation phase detection is 67.2% and the accuracy of cyclic alternating pattern detection is 61.5%.

An optical scheme for quantum multi-service network

Quantum Inf. Comput., 2012

Several quantum protocols for data security having been proposed and, in general, they have diffe... more Several quantum protocols for data security having been proposed and, in general, they have different optical implementations. However, for the implementation of quantum protocols in optical networks, it is highly advantageous if the same optical setup can be used for running different quantum communication protocols. In this direction, here we show an optical scheme that can be used for quantum key distribution (QKD), quantum secure direct communication (QSDC) and quantum secret sharing (QSS). Additionally, it is naturally resistant to the attack based on single-photon detector blinding. At last, we show a proof-of-principle experiment in 1 km optical fiber link that shows the feasibility of the proposed scheme.

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Sleep Quality Analysis with Cardiopulmonary Coupling

2018 International Conference on Biomedical Engineering and Applications (ICBEA), 2018

Sleep quality is commonly assessed with subject self-reporting, interviews and psychological vari... more Sleep quality is commonly assessed with subject self-reporting, interviews and psychological variables. However, more precise methods comprise estimation of physiological signals where polysomnography is considered to be the gold standard and can be performed to produce qualitative or quantitative measurements regarding the subjects sleep. However, polysomnography is known to be a complex and expensive process that is inaccessible to a large group of the population. The main objective of this work is to produce an algorithm that is capable to ascertain sleep quality, using only data from a single-lead electrocardiogram, that can be implemented in a small digital signal processor or a small field-programmable gate array. Therefore, providing a tool that can be used for identifying the need of a polysomnography analysis or as a complementary method to improve the detection capability of other pathologies. The employed method first determined both normal-to-normal sinus interbeat inter...

A Proposal for Single-Photon Detection in Millimeter-Wave and THz Regions

2021 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC), 2021

Quantum key distribution (QKD) allows secure communication between spatially distant users. It ha... more Quantum key distribution (QKD) allows secure communication between spatially distant users. It has been successfully implemented in fiber-based and free space optical networks. However, QKD has not been implemented in other important regions of the electromagnetic spectrum: millimeter- wave and THz regions. One of the reasons for this is that single- photon detectors in these regions are not easily available. In the present work, a proposal of a simple and cheap single-photon detector working in the mmWave and THz region, using glow discharge detector, is presented and its parameters are discussed.

A minimallyinvasive portable system for sleep apnea detection

2017 International Conference and Workshop on Bioinspired Intelligence (IWOBI), 2017

Health care is changing the focus from primary and specialty care to prevention and wellness. The... more Health care is changing the focus from primary and specialty care to prevention and wellness. Therefore, home health care is seen as one of the most relevant wellness services due to high accessibility and low cost of diagnosis. The growth relevance given to the sleep related disorders, due to the high importance of sleep in our lives, is specifically significant in this context encouraging the development of methods capable of non-invasively monitor and detection. One of the most relevant sleep disorders is obstructive sleep apnea, being the focus of the work presented in this paper to develop a minimally invasive portable system to detect this disorder using only oximetry. The system developed in this work is capable of collecting the oxygen saturation and pulse rate signals and send them wirelessly to the processing station where an application records and analyses the data. A graphical user interface guides the patients to start the monitoring session and a report is produced at...

SpO2 based sleep apnea detection using deep learning

2017 IEEE 21st International Conference on Intelligent Engineering Systems (INES), 2017

In a classical classification process, automatic sleep apnea detection involves creating and sele... more In a classical classification process, automatic sleep apnea detection involves creating and selecting the features, using prior knowledge, and apply them to a classifier. A different approach is applied in this paper, where a Deep Belief Network is used for feature extraction, without using domain-specific knowledge, and then the same network is used for classification of sleep apnea. The Deep Belief Network was created by stacking Restricted Boltzmann Machines. The first two layers are autoencoder type and the last layer is of soft-max type. The initial weights are calculated using unsupervised learning and, at the end, a supervised fine-tuning of the weights is performed. Two public databases, one with 8 subjects and other with 25 subjects, are tested using tenfold cross validation. The optimum number of hidden neurons of this problem is found using a search technique. The accuracy achieved from UCD database is 85.26% and Apnea-ECG database is 97.64%.

Multi-Objective Hyperparameter Optimization of Convolutional Neural Network for Obstructive Sleep Apnea Detection

IEEE Access, 2020

Obstructive sleep apnea (OSA) is a common sleep disorder characterized by interrupted breathing d... more Obstructive sleep apnea (OSA) is a common sleep disorder characterized by interrupted breathing during sleep. Because of the cost, complexity, and accessibility issue related to polysomnography, the gold standard test for apnea detection, automation of the diagnostic test based on a simpler method is desired. Several signals can be used for apnea detection, such as airflow and electrocardiogram. However, the reduction of airflow normally leads to a decrease in the blood oxygen saturation level (SpO2). This signal is usually measured by a pulse oximeter, a sensor that is cheap, portable, and easy to assemble. Therefore, the SpO2 was chosen as the reference signal. Feature based classifiers with shallow neural networks have been developed to provide apnea detection using SpO2. However, two main issues arise, the need for feature creation and the selection of the more relevant features. Deep neural networks can solve these issues by employing featureless methods. Among multiple deep classifiers that have been developed, convolution neural networks (CNN) are gaining popularity. However, the selection of the CNN structure and hyperparameters are typically done by experts, where prior knowledge is essential. With these problems in mind, an algorithm for automatic structure selection and hyper parameterization of a one dimension CNN was developed to detect OSA events using only the SpO2 signal. Three different input sizes and databases were tested, and the best model achieved an average accuracy, sensitivity, and specificity of 94%, 92%, and 96%, respectively.

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A low cost FPGA based thermal imaging camera for fault detection in PV panels

2017 International Conference on Internet of Things for the Global Community (IoTGC), 2017

This paper demonstrates the development of a low cost thermal imaging camera as an alternative to... more This paper demonstrates the development of a low cost thermal imaging camera as an alternative to the commercial models. This device consists on a long wave infrared sensor which captures the infrared reflection from the physical objects. Thermal imaging camera technology has provided relevant developments for security systems, being used in surveillance activities such as law-enforcement, home intrusion detection and power line maintenance. However, it has also been used on different areas and the main objective, for this project, is to test it on solar panels in order to detect overheating cells. Commercial thermal imaging cameras are expensive, as their price varies from 1000 to 7000€. The starting point of this work was the belief that a lower cost version (around 700€) with a reasonable performance can be developed and has a potential market entry. Overall, after developing and testing the prototype, it proved that the premise is correct and, with some improvements, it can be used for commercial purposes.

A Method for Sleep Quality Analysis Based on CNN Ensemble With Implementation in a Portable Wireless Device

IEEE Access, 2020

The quality of sleep can be affected by the occurrence of a sleep related disorder and, among the... more The quality of sleep can be affected by the occurrence of a sleep related disorder and, among these disorders, obstructive sleep apnea is commonly undiagnosed. Polysomnography is considered to be the gold standard for sleep analysis. However, it is an expensive and labor-intensive exam that is unavailable to a large group of the world population. To address these issues, the main goal of this work was to develop an automatic scoring algorithm to analyze the single-lead electrocardiogram signal, performing a minute-by-minute and an overall estimation of both quality of sleep and obstructive sleep apnea. The method employs a cross-spectral coherence technique which produces a spectrographic image that fed three one-dimensional convolutional neural networks for the classification ensemble. The predicted quality of sleep was based on the electroencephalogram cyclic alternating pattern rate, a sleep stability metric. Two methods were developed to indirectly evaluate this metric, creating two sleep quality predictions that were combined with the sleep apnea diagnosis to achieve the final global sleep quality estimation. It was verified that the quality of sleep of the nineteen tested subjects was correctly identified by the proposed model, advocating the significance of clinical analysis. The model was implemented in a non-invasive and simple to self-assemble device, producing a tool that can estimate the quality of sleep and diagnose the obstructive sleep apnea at the patient's home without requiring the attendance of a specialized technician. Therefore, increasing the accessibility of the population to sleep analysis.

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A Review of Approaches for Sleep Quality Analysis

IEEE Access, 2019

Sleep quality is directly related to overall wellness and can reveal symptoms of several diseases... more Sleep quality is directly related to overall wellness and can reveal symptoms of several diseases. However, the term ''sleep quality'' still lacks a definitional consensus and is commonly assessed in sleep labs with polysomnography, comprising high costs, or through sleep questionnaires, a highly subjective technique. Multiple methods have been proposed to address the estimation of sleep quality, and devices were developed to conduct the examination in the subject's home. The objective of this paper is to analyze the methods and the devices presented in the literature, assessing the development of objective markers that could lead to an improvement of the subjective sleep experience understanding, leading to developments in the treatment of sleep quality deficits. A systematic review was conducted, selecting research articles published from 2000 to 2018, and two research questions were formulated, specifically, ''what methods for sleep quality assessment have been developed'' and ''what kind of measures are employed by the devices that have been developed to estimate sleep quality.'' The research trend for the assessment of sleep quality is based on the sleep macrostructure, and it was verified that despite the convenience and considerable popularity among the consumers of home health monitoring of devices, such as actigraphs, the validity of these tools regarding the estimation of sleep quality still needs to be systematically examined. A detailed resume of the key findings and the identified challenges are presented, ascertaining the main gaps in the current state of the art. INDEX TERMS Sleep quality analysis, monitoring devices, home detection.

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Sleep Quality Estimation by Cardiopulmonary Coupling Analysis

IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2018

The gold standard for assessment of sleep quality is the polysomnography where physiological sign... more The gold standard for assessment of sleep quality is the polysomnography where physiological signals are used to generate both quantitative and qualitative measurements. Despite the production of highly accurate results, polysomnography is a complex, uncomfortable and expensive process, inaccessible to a large group of the population. Home monitoring devices were developed to address these issues, fitting the growing perspective of health care and focusing in prevention and wellness. The objective of this work was to develop an algorithm capable of estimating the quality of sleep, by analyzing the cyclic alternating pattern rate. The algorithm uses a single-lead electrocardiogram to produce a spectrographic measure of the cardiopulmonary coupling that in turn was fed to a classifier to estimate the nonrapid eye movement sleep and the presence of the cyclic alternating pattern. Two classifiers were tested, a feedforward neural network and a deep stacked autoencoder, with the second achieving better results, correctly classifying 77% of the subjects sleep quality (either good or bad). The developed method can be implemented in a home monitoring device to estimate the sleep quality in a non-invasive way and improve the detection of pathologies.

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A Review of Obstructive Sleep Apnea Detection Approaches

IEEE journal of biomedical and health informatics, Jan 4, 2018

Sleep disorders are a common health condition that can affect numerous aspects of life. Obstructi... more Sleep disorders are a common health condition that can affect numerous aspects of life. Obstructive sleep apnea is one of the most common disorders and is characterized by a reduction or cessation of airflow during sleep. In many countries this disorder is usually diagnosed in sleep laboratories, by a polysomnography, which is an expensive procedure involving much effort for the patient. Multiple systems have been proposed to address this situation, including performing the examination and analysis in the patient's home, using sensors to detect physiological signals that are automatically analyzed by algorithms. However, the precision of these devices is usually not enough to provide a clinical diagnosis. Therefore, the objective of this review is to analyze already existing algorithms that have not been implemented on hardware but have had their performance verified by at least one experiment which aims to detect obstructive sleep apnea, in order to show future trends. The perf...

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Avaliação do temperamento de terneiros Brangus de diferentes graus de sangue

Anais Do Salao Internacional De Ensino Pesquisa E Extensao, 2012

Entre os diversos criterios a serem selecionados em uma populacao de bovinos de corte pode-se des... more Entre os diversos criterios a serem selecionados em uma populacao de bovinos de corte pode-se destacar o temperamento, uma vez que este esta diretamente ligado ao valor economico da atividade. Neste contexto, destaca-se o fato de animais menos reativos apresentarem melhor desempenho, maior producao de leite e menor numero de lesoes e contusoes na carcaca. O objetivo deste estudo foi avaliar o temperamento de terneiros Brangus de diferentes graus de sangue. Foram utilizados 190 terneiros Brangus ao sobreano (18 meses) de diferentes graus de sangue: animais 3/8 Nelore x 5/8 Angus (Grupo BN) e animais filhos de vacas BN com touros Nelore: 5/16 Angus x 11/16 Nelore (Grupo Nelore). O temperamento foi mensurado atraves de duas metodologias: pela velocidade de fuga, medida com auxilio de equipamento especifico (fly speed) e atraves do equipamento denominado Reatest®. A primeira metodologia consiste em duas celulas que registram a velocidade com que o animal percorre uma distância conhecida (dois metros), apos saida da balanca. O segundo metodo consiste em um equipamento que e acoplado na base da balanca (sensor de movimento) e registra as oscilacoes que a mesma sofre pela agitacao do animal, durante 20 segundos. Os efeitos fixos considerados foram o grau de sangue e sexo dos animais, e as variaveis foram as medidas de temperamento, mensuradas pelos dois metodos. Para analise de variância utilizou-se o procedimento GLM do SAS, versao 9.2 (2008), e a correlacao entre as duas metodologias foi avaliada atraves da correlacao de Spearman. Nao houve efeito dos efeitos fixos para a variavel velocidade de fuga (P>0,05). Para a variavel reatividade medida pelo Reatest® houve efeito significativo (P

Influência Do Tipo De VeÍculo No Aparecimento De Edemas Em Carcaças Bovinas

Anais Do Salao Internacional De Ensino Pesquisa E Extensao, 2011

Nos ultimos anos os sistemas de producao tem evoluido em direcao a diferenciacao de produtos mais... more Nos ultimos anos os sistemas de producao tem evoluido em direcao a diferenciacao de produtos mais qualificados, atendendo desta forma, uma crescente demanda por carne nobre. Devido a isso, industrias de frigorificos e abatedouros sao induzidas a melhor remunerar por estes produtos. Porem, estas empresas ainda se deparam com problemas logisticos na etapa final da producao, e que, certamente influenciam no aparecimento de edemas em carcacas afetando de modo quantitativo e, ou qualitativo, na medida em que estes precisam ser removidos na linha de abate, trazendo desta forma, reflexos negativos. Com isso objetivou-se neste estudo, identificar aspectos responsaveis pelas perdas por edemas em carcacas bovinas na etapa pre-abate em um frigorifico localizado em Santa Maria. Por ser o principal meio de transporte de bovinos para o frigorifico, foi verificada a influencia que os caminhoes boiadeiros ocasionam no aparecimento de edemas em carcacas. Para isso, foram contabilizados os edemas nas carcacas na linha de abate de acordo com a localizacao: coxa, lombo, dianteiro e costela, e relacionados a quatro tipos de veiculos com diferentes compartimentos e dimensoes: Caminhao trucado com capacidade media de 27 animais responsavel por 44% das viagens neste estudo, a Carreta com capacidade de 37 animais responsavel por 24%, a Julieta para 45 animais responsavel por 23% e a Carreta Grande com capacidade de transporte medio de 50 animais responsavel por 7%. Os dados foram analisados estatisticamente por meio de analise de variância (PROC GLM), como variaveis independentes no software SAS, ao nivel de 10% de significância. Foram utilizados 303 lotes de animais transportados no mes de marco e, embora se tenha notado um efeito significativo (P0,10) e estes veiculos geraram um menor numero de edemas, 8,00 e 7,50, respectivamente para a regiao da costela. Para os demais cortes, nao foram encontradas diferencas significativas (P>0,10) pelo tipo de veiculo utilizado. Esses dados permitem concluir que os veiculos pequenos, Julieta e Caminhao trucado, sao os mais eficientes no transporte de bovinos, pois geraram um menor numero de edemas nas carcacas se comparados a veiculos maiores, Carreta e Carreta grande.

Reatividade de vacas leiteiras da raça Holandesa utilizando diferentes metodologias

Anais Do Salao Internacional De Ensino Pesquisa E Extensao, 2011

Na bovinocultura leiteira, a ordenha e uma das atividades de rotina diaria da fazenda e existem e... more Na bovinocultura leiteira, a ordenha e uma das atividades de rotina diaria da fazenda e existem evidencias de que a quebra dessa rotina, atraves da falta de previsibilidade das acoes de manejo, pode causar desconforto resultando na inquietacao dos animais. A troca do manejo de ordenha de manual para mecânico oferece ao produtor a possibilidade de aumentar a produtividade, mas pode alterar dramaticamente a percepcao do animal quanto a rotina em seu ambiente, podendo trazer como consequencias imediatas em relacao ao seu bem-estar. Entretanto e dificil conhecer potenciais e limitacoes com respeito ao bem-estar animal em rebanhos leiteiros, sendo necessario o desenvolvimento de protocolos de descricao do comportamento para serem facilmente utilizados como ferramenta de suporte de decisao quanto ao bem-estar desse tipo de animal. Baseado nisso, a realizacao do presente trabalho objetivou avaliar dois protocolos de acesso a reatividade de vacas em lactacao submetidas a mudancas nas instalacoes, do sistema balde ao pe para o sistema espinha de peixe. Para verificacao do comportamento em sala de ordenha foram observadas 23 vacas em lactacao, da raca Holandesa, de uma propriedade particular localizada no municipio de Sant’Ana do Livramento (RS), durante o periodo equivalente aos sete primeiros dias de ordenha em espinha de peixe 3x3, posicionada no sentido norte-sul. A reatividade foi avaliada de acordo com a movimentacao dos membros posteriores, sendo atribuido escore 1 para os animais que mantivessem os membros imoveis; 2 para os membros posteriores em movimento, sem levanta-los acima de 15 cm; e 3 para os membros posteriores em movimento, levantando-o acima de 15 cm. Estes escores foram distribuidos de acordo com duas metodologias diferentes, sendo que no metodo 1 (MET1) foram considerados reativos os animais que movimentaram os membros em pelo menos um periodo e como nao reativos aqueles que permaneceram com os membros imoveis em todos os periodos. No metodo 2 (MET2) foram considerados reativos os animais que elevaram os membros acima de 15 cm do solo e como nao reativos aqueles que permaneceram imoveis ou movimentaram os membros abaixo de 15 cm. Os resultados obtidos mostraram que no MET1 a maioria dos animais foi classificada como reativa (n=20/22), enquanto que no MET2 45,5% (n=10) das vacas foram classificadas como reativas e 54,5% (n=12) classificadas como nao reativas. Nao foi observada correlacao (P>0,05) entre reatividade e os tempos de ordenha. A partir dos resultados obtidos pode-se concluir que nao houve diferenca entre o tempo gasto na ordenha pelos animais considerados reativos ou nao reativos, a partir dos dois metodos de avaliacao da reatividade.

Avaliação Econômica Da Carcaça De Machos Nelore Não Castrados Abatidos Com Diferentes Pesos

Anais Do Salao Internacional De Ensino Pesquisa E Extensao, 2011

Os incrementos de produtividade da bovinocultura de corte passam pela reducao da idade de abate d... more Os incrementos de produtividade da bovinocultura de corte passam pela reducao da idade de abate dos machos. Entretanto, isso somente e viavel se os novilhos atingirem peso adequado e grau de acabamento que atenda as exigencias dos frigorificos. Algumas pesquisas vem sendo desenvolvidas a fim de esclarecer a importância da reducao da idade de abate nos indices produtivos e economicos, alem de estudar a reducao maxima da idade de abate dos machos, buscando determinar o peso de abate adequado, que ira determinar o tempo necessario para a terminacao dos animais, momento mais oneroso do processo de producao de bovinos de corte. Assim, a partir de dados referenciais de precos de mercado, o objetivo deste trabalho e realizar uma avaliacao economica do abate de carcaca de machos Nelore jovens, nao castrados, abatidos com diferentes pesos. Para o experimento utilizou-se 40 bovinos da raca Nelore, machos inteiros,com idade media de dois anos, e peso medio inicial de 350 kg. Sendo estes divididos em quatro grupos: animais 0 e 2 dentes, com peso de carcaca de ate 238,0 kg (jovens e carcacas leves); animais 2 dentes com peso de carcaca variando de 238,1 a 258,0 kg (jovens e carcacas medias); animais 2 dentes com peso de carcaca superior a 258,0 kg (jovens e carcacas pesadas) e animais com 4 ou 6 dentes, independente do peso de carcaca (adultos). Os animais recebiam uma dieta contendo 60% de silagem de milho e 40% de concentrado. Foram medidos os pesos dos cortes desossados das carcacas e, ao dividir a receita com a venda dos cortes pelo peso de carcaca de cada grupo de animais, obteve-se o preco de equilibrio para aquisicao do animal gordo que pode ser pago pela industria frigorifica, sem considerar as receitas com outros componentes nao carcaca e diferencas no custo de industrializacao em funcao de peso de carcaca. Obteve-se uma diferenca de receita da venda de cortes de 10,06% entre animais jovens com carcacas pesadas em relacao aos animais com carcacas leves, mas a diferenca no preco do ponto de equilibrio de aquisicao do animal gordo e de 7,40% favoravel aos animais leves. Isso se deve porque os R$ 1.542,12 gerados com uma carcaca jovem e pesada, precisam remunerar o produtor em 273 kg de carcaca, ao passo que os R$ 1.401,13 gerados na receita da carcaca leve, precisa remunerar ao produtor apenas 230 kg de carcaca. Quando comparados animais adultos com os animais jovens e com carcacas leves. A diferenca na receita da venda dos cortes primarios atinge apenas 3,57%, mas o preco do ponto de equilibrio pode ser de ate 9,81% a mais para os animais jovens. O preco de equilibrio na aquisicao do boi gordo que pode ser ofertado pelo frigorifico ao produtor, pode oscilar entre 7 e 10%, se desconsiderados os rendimentos de componentes nao carcaca e custos industriais. No entanto, para o produtor a elevacao do peso de bate nao apresenta vantagem aparente, a medida que a eficiencia alimentar decresce com o avanco do periodo de terminacao e do peso de abate dos animais

Hybrid Parallel Quantum Key Distribution Protocol

The practical realizations of BB84 quantum key distribution protocol using single-photon or weak ... more The practical realizations of BB84 quantum key distribution protocol using single-photon or weak coherent states have normally presented low efficiency, in the meaning that most bits sent by Alice are not useful for the final key. In this work, we show an optical setup to improve the transmission rate of useful bits putting together two ideas, parallel quantum key distribution

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Small scale wind energy harvesting with maximum power tracking

AIMS Energy, 2015

It is well-known that energy harvesting from wind can be used to power remote monitoring systems.... more It is well-known that energy harvesting from wind can be used to power remote monitoring systems. There are several studies that use wind energy in small-scale systems, mainly with wind turbine vertical axis. However, there are very few studies with actual implementations of small wind turbines. This paper compares the performance of horizontal and vertical axis wind turbines for energy harvesting on wireless sensor network applications. The problem with the use of wind energy is that most of the time the wind speed is very low, especially at urban areas. Therefore, this work includes a study on the wind speed distribution in an urban environment and proposes a controller to maximize the energy transfer to the storage systems. The generated power is evaluated by simulation and experimentally for different load and wind conditions. The results demonstrate the increase in efficiency of wind generators that use maximum power transfer tracking, even at low wind speeds.

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Quantum key distribution with error rejecting protocol: optical setup and security analysis

2006 International Telecommunications Symposium, 2006

This work discuss an error rejection optical setup, using linear optical devices, and its use in ... more This work discuss an error rejection optical setup, using linear optical devices, and its use in the BB84 quantum key distribution protocol. In order to analyze the security, the Fuchs-Peres-Brandt attack is considered. We showed that the security is improved by the use of the rejection error protocol.

Fabio Mendonca

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