Multipacket reception in the presence of in-band full-duplex communication

In-Band Full-DupleX (IB-FDX) is defined as the ability for nodes to transmit and receive signals simultaneously on the same channel. Conventional digital wireless networks do not implement it, since a node’s own transmission signal causes interference to the signal it is trying to receive. However, recent studies attempt to overcome this obstacle, since it can potentially double the spectral efficiency of current wireless networks. Different mechanisms exist today that are able to reduce a significant part of the Self- Interference (SI), although specially tuned Medium Access Control (MAC) protocols are required to optimize its use. One of IB-FDX’s biggest problems is that the nodes’ interference range is extended, meaning the unusable space for other transmissions and receptions is broader. This dissertation proposes using MultiPacket Reception (MPR) to address this issue and adapts an already existing Single-Carrier with Frequency-Domain Equalization (SC-FDE) receiver to IB-FDX. The performance analysis suggests that MPR and IB-FDX have a strong synergy and are able to achieve higher data rates, when used together. Using analytical models, the optimal transmission patterns and transmission power were identified, which maximize the channel capacity with the minimal energy consumption. This was used to define a new MAC protocol, named Full-duplex Multipacket reception Medium Access Control (FM-MAC). FM-MAC was designed for a single-hop cellular infrastructure, where the Access Point (AP) and the terminals implement both IB-FDX and MPR. It divides the coverage range of the AP into a closer Full-DupleX (FDX) zone and a farther Half-DupleX (HDX) zone and adds a tunable fairness mechanism to avoid terminal starvation. Simulation results show that this protocol provides efficient support for both HDX and FDX terminals, maximizing its capacity when more FDX terminals are used.

Blocking tumor exosome release using nanovectorization systems

Exosomes are small membrane vesicles secreted by most cell types, either normal or malignant and are found in most body fluids such as saliva, plasma and breast milk. In the past decade, the interest in these vesicles has been growing more and more since it was found that besides their beneficial functions such as the removal of cellular debris and unnecessary proteins during cell maturation process, they can also interact with other cells and transfer information between them, thus helping diseases like cancer to progress. The present work intended to use gold nanoparticles as vehicles for gene silencing in an attempt to reduce the tumor-derived exosome secretion, regulated by Rab27a protein, and also aimed to compare the exosome secretion between two breast cell lines, MCF7 and MDA. Changes in RAB27A gene expression were measured by Real-time Quantitative PCR and it was revealed a decreased in RAB27A gene expression, as expected. Exosomes were isolated and purified by two different methods, ultracentrifugation and the commercial kit ExoQuick™ Solution, and further characterized using Western Blot analysis. ExoQuick™ Solution was proven to be the most efficient method for exosome isolation and it was revealed that MDA cells secrete more exosomes. Furthermore, the isolated MCF7-derived exosomes were placed together with a normal bronchial/tracheal epithelial cell line (BTEC) for an additional assay, which aimed to observe the uptake of exosomes by other cells and the exosomes’ capability of promoting cell-cell communication. This observation was made based on alterations in the expression levels of c-Myc and miR-21 genes and the fact that they both have an increased expression in BTEC cells incubated with tumor-derived exosomes when compared to control cells (without incubation with the exosomes) lead us to the conclusion that the exosome uptake and exchange of information between the exosomes and the normal cells did occurred.

Aprendizagem, mobilidade e convergência digital no ambiente formativo da Portugal Telecom

Com o desenvolvimento das Tecnologias de Informação e Comunicação, as mesmas têm permitido dotar as pessoas de conhecimentos, através de formas mais rápidas e eficientes como é o caso da formação em e-learning. O número de organizações a apostar na formação em e-learning é cada vez maior, tornando-se importante perceber em que medida é que o método é eficaz e quais as vantagens que proporciona à organização, bem como o seu impacto no capital humano. Assim e visando averiguar como esta situação é vivenciada na prática decidiu-se pela realização de um estágio, na PT PRO pertencente Grupo Portugal Telecom. Para a construção deste relatório de estágio foi preciso para além da consulta e análise documental de aquivos internos e intranet, reuniões tidas com os elementos do departamento da Gestão de Formação, onde decorreu o estágio, visando dar uma resposta mais cabal à questão de partida que norteia o estágio: “Qual o impacto gerado pelas ações de e-learning, sua aplicabilidade e satisfação dos colaboradores face às mesmas na PT PRO?” O método utilizado neste estudo foi do tipo quantitativo, tendo sido aplicado um inquérito por questionário construído para o efeito. Face aos resultados obtidos, concluímos que na PT PRO, os colaboradores encontram-se globalmente satisfeitos com o conhecimento gerado e acima de tudo com a aplicabilidade do mesmo nas suas funções de trabalho.

Tecnologias da informação e comunicação na formação continuada de professores: estudode caso em escolas do Brasil e Portugal com recursos e aplicação do Google+

Tese de Doutoramento em Ciências da Educação (área de especialização em Tecnologia Educativa)

Effect of the acoustic impedance in ultrasonic emitter transducers using digital modulations

In an underwater environment it is difficult to implement solutions for wireless communications. The existing technologies using electromagnetic waves or lasers are not very efficient due to the large attenuation in the aquatic environment. Ultrasound reveals a lower attenuation, and thus has been used in underwater long-distance communications. The much slower speed of acoustic propagation in water (about 1500 m/s) compared with that of electromagnetic and optical waves, is another limiting factor for efficient communication and networking. For high data-rates and real-time applications it is necessary to use frequencies in the MHz range, allowing communication distances of hundreds of meters with a delay of milliseconds. To achieve this goal, it is necessary to develop ultrasound transducers able to work at high frequencies and wideband, with suitable responses to digital modulations. This work shows how the acoustic impedance influences the performance of an ultrasonic emitter transducer when digital modulations are used and operating at frequencies between 100 kHz and 1 MHz. The study includes a Finite Element Method (FEM) and a MATLAB/Simulink simulation with an experimental validation to evaluate two types of piezoelectric materials: one based on ceramics (high acoustic impedance) with a resonance design and the other based in polymer (low acoustic impedance) designed to optimize the performance when digital modulations are used. The transducers performance for Binary Amplitude Shift Keying (BASK), On-Off Keying (OOK), Binary Phase Shift Keying (BPSK) and Binary Frequency Shift Keying (BFSK) modulations with a 1 MHz carrier at 125 kbps baud rate are compared.

Circuito de leitura digital para MEMS capacitivos

Dissertação de mestrado integrado em Engenharia Eletrónica Industrial e Computadores

Luto digital: plataformas para a gestão da herança digital

Dissertação de mestrado integrado em Engenharia e Gestão de Sistemas de Informação

As políticas tecnológicas para a educação e a literacia digital: o caso do programa governamental ‘e.escolinha’

Em 2008, o Governo português anunciou a iniciativa ‘e.escolinha’ que contemplou a distribuição de computadores ‘Magalhães’ aos alunos do 1º ciclo do ensino básico, durante três anos letivos consecutivos. Atualmente suspenso, o programa foi bandeira do XVII Governo Constitucional, liderado por José Sócrates, mas alvo de controvérsias por parte da oposição política e da comunidade escolar, sobretudo pela aparente tónica no acesso à tecnologia em vez de uma maior preocupação com a formação e as práticas pedagógicas. Ao abrigo do Plano Tecnológico da Educação, o ‘e.escolinha’ inseria-se numa política mais ampla para o desenvolvimento de uma economia competitiva e dinâmica, através das metas estabelecidas pela União Europeia na Estratégia de Lisboa 2000. A iniciativa foi apresentada ao país com objetivos ambiciosos, no que diz respeito às esperadas mudanças ao nível das práticas pedagógicas dos professores, do processo de aprendizagem das crianças e do sucesso escolar em geral. Porém, a face mais visível da política, embora possa compreender outros matizes, poderá ter ficado reduzida à questão do acesso, apostando pouco nas outras dimensões da literacia digital. Com base em entrevistas realizadas a atores-chave envolvidos no processo de conceção e implementação do ‘e.escolinha’, e nos documentos oficiais que enquadram o programa, o presente artigo pretende dar a conhecer a forma como decisores políticos e empresas enunciam e avaliam os objetivos desta iniciativa. Pretende-se, em particular, conhecer se partilham a ideia de uma deriva tecnológica desta medida governamental ou se entreveem, na mesma, objetivos de literacia digital. Este trabalho decorre do projeto de investigação “Navegando com o Magalhães: Estudo sobre o Impacto dos Media Digitais nas Crianças”, em curso no Centro de Estudos de Comunicação e Sociedade da Universidade do Minho, financiado pela Fundação para a Ciência e Tecnologia ((PTDC/CCI-COM/101381/2008) ) e co-financiado pelo FEDER (COMPETE: FCOMP-01-0124-FEDER-009056).

Digital literacy, technology and social inclusion: making sense of one-to-one computer programmes around the world

This book was produced in the scope of a research project entitled “Navigating with ‘Magalhães’: Study on the Impact of Digital Media in Schoolchildren”. This study was conducted between May 2010 and May 2013 at the Communication and Society Research Centre, University of Minho, Portugal and it was funded by the Portuguese Foundation for Science and Technology (PTDC/CCI-COM/101381/2008).

Introduction [to Digital literacy, technology and social inclusion: making sense of one-to-one computer programmes around the world]

This book was produced in the scope of a research project entitled “Navigating with ‘Magalhães’: Study on the Impact of Digital Media in Schoolchildren”. This study was conducted between May 2010 and May 2013 at the Communication and Society Research Centre, University of Minho, Portugal and it was funded by the Portuguese Foundation for Science and Technology (PTDC/CCI-COM/101381/2008). As we shall explain in more detail later in this book, the main objective of that research project was to analyse the impact of the Portuguese government programme named ´e-escolinha´ launched in 2008 within the Technological Plan for Education. This Plan responds to the principles of the Lisbon Strategy signed in 2000 and rereleased in the Spring European Council of 2005.

Computer integrated testing for the transport refrigeration systems industry.

This is a study of a state of the art implementation of a new computer integrated testing (CIT) facility within a company that designs and manufactures transport refrigeration systems. The aim was to use state of the art hardware, software and planning procedures in the design and implementation of three CIT systems. Typical CIT system components include data acquisition (DAQ) equipment, application and analysis software, communication devices, computer-based instrumentation and computer technology. It is shown that the introduction of computer technology into the area of testing can have a major effect on such issues as efficiency, flexibility, data accuracy, test quality, data integrity and much more. Findings reaffirm how the overall area of computer integration continues to benefit any organisation, but with more recent advances in computer technology, communication methods and software capabilities, less expensive more sophisticated test solutions are now possible. This allows more organisations to benefit from the many advantages associated with CIT. Examples of computer integration test set-ups and the benefits associated with computer integration have been discussed.

middleware for cooperating mobile embedded systems

Mobile embedded systems, wireless communication, real-time systems, real-time scheduling, communication protocols, cooperation, reliability and fault-tolerance, middleware

Using a NPWE model observer to assess suitable image quality for a digital mammography quality assurance programme.

A method of objectively determining imaging performance for a mammography quality assurance programme for digital systems was developed. The method is based on the assessment of the visibility of a spherical microcalcification of 0.2 mm using a quasi-ideal observer model. It requires the assessment of the spatial resolution (modulation transfer function) and the noise power spectra of the systems. The contrast is measured using a 0.2-mm thick Al sheet and Polymethylmethacrylate (PMMA) blocks. The minimal image quality was defined as that giving a target contrast-to-noise ratio (CNR) of 5.4. Several evaluations of this objective method for evaluating image quality in mammography quality assurance programmes have been considered on computed radiography (CR) and digital radiography (DR) mammography systems. The measurement gives a threshold CNR necessary to reach the minimum standard image quality required with regards to the visibility of a 0.2-mm microcalcification. This method may replace the CDMAM image evaluation and simplify the threshold contrast visibility test used in mammography quality.

Copper filtration in pediatric digital X-ray imaging: its impact on image quality and dose.

The effect of copper (Cu) filtration on image quality and dose in different digital X-ray systems was investigated. Two computed radiography systems and one digital radiography detector were used. Three different polymethylmethacrylate blocks simulated the pediatric body. The effect of Cu filters of 0.1, 0.2, and 0.3 mm thickness on the entrance surface dose (ESD) and the corresponding effective doses (EDs) were measured at tube voltages of 60, 66, and 73 kV. Image quality was evaluated in a contrast-detail phantom with an automated analyzer software. Cu filters of 0.1, 0.2, and 0.3 mm thickness decreased the ESD by 25-32%, 32-39%, and 40-44%, respectively, the ranges depending on the respective tube voltages. There was no consistent decline in image quality due to increasing Cu filtration. The estimated ED of anterior-posterior (AP) chest projections was reduced by up to 23%. No relevant reduction in the ED was noted in AP radiographs of the abdomen and pelvis or in posterior-anterior radiographs of the chest. Cu filtration reduces the ESD, but generally does not reduce the effective dose. Cu filters can help protect radiosensitive superficial organs, such as the mammary glands in AP chest projections.

Design of Novel Frequency Generation Circuit with Application to Ultra-Wideband Distributed Oscillators

Given the urgence of a new paradigm in wireless digital trasmission which should allow for higher bit rate, lower latency and tigher delay constaints, it has been proposed to investigate the fundamental building blocks that at the circuital/device level, will boost the change towards a more efficient network architecture, with high capacity, higher bandwidth and a more satisfactory end user experience. At the core of each transciever, there are inherently analog devices capable of providing the carrier signal, the oscillators. It is strongly believed that many limitations in today's communication protocols, could be relieved by permitting high carrier frequency radio transmission, and having some degree of reconfigurability. This led us to studying distributed oscillator architectures which work in the microwave range and possess wideband tuning capability. As microvave oscillators are essentially nonlinear devices, a full nonlinear analyis, synthesis, and optimization had to be considered for their implementation. Consequently, all the most used nonlinear numerical techniques in commercial EDA software had been reviewed. An application of all the aforementioned techniques has been shown, considering a systems of three coupled oscillator ("triple push" oscillator) in which the stability of the various oscillating modes has been studied. Provided that a certain phase distribution is maintained among the oscillating elements, this topology permits a rise in the output power of the third harmonic; nevertheless due to circuit simmetry, "unwanted" oscillating modes coexist with the intenteded one. Starting with the necessary background on distributed amplification and distributed oscillator theory, the design of a four stage reverse mode distributed voltage controlled oscillator (DVCO) using lumped elments has been presented. All the design steps have been reported and for the first time a method for an optimized design with reduced variations in the output power has been presented. Ongoing work is devoted to model a wideband DVCO and to implement a frequency divider.