Mortality and Longevity Projections for the Oldest-Old in Portugal

The mortality decline observed in developed countries over the last decades significantly increased the number of those surviving up to older ages. Mortality improvements are naturally viewed as a positive change for individuals and as a substantial social achievement for societies, but create new challenges in a number of different areas, ranging from the planning of all components of social security systems to labour markets. Understanding mortality and survival patterns at older ages is crucial. In this paper, we compare the results provided by a number of different methods designed to project mortality for the oldest-old in the Portuguese population. We identify the merits and limitations of each method and the consequences of their use in constructing complete life tables

A Digital Microfluidics Platform for Loop-Mediated Isothermal Amplification of DNA

Digital Microfluidics (DMF) is an innovative technology for liquid manipulation at microliter- to picoliter-scale, with tremendous potential of application in biosensing. DMF allows maneuvering single droplets over an electrode array, by means of electrowetting-on-dielectric (EWOD), that allows changing the contact angle of a droplet over a dielectric. Each droplet is thus considered a microreactor, with an unparalleled potential to perform chemical and biological reactions. Several aspects inherent to DMF platforms, such as multiplex assay capability and integration capability, make them promising for lab-on-chip and point-of-care (PoC) applications, e.g. DNA amplification assays or disease detection. DNA detection strategies for PoC have been profiting from recent development of isothermal amplification schemes, of which Loop-mediated Isothermal Amplification (LAMP) is a major methodology, allowing a 109-fold amplification efficiency in one hour. Here, I demonstrate for the first time the effective coupling of DMF and LAMP, resulting in a DMF device capable of performing LAMP reactions. This novel DMF platform has been developed and characterised, which allows successful amplification of a c-Myc gene fragment by LAMP. Precise temperature control is achieved by using a transparent heating element, connected to a looping feedback control system. This platform is able to amplify just 0.5 ng/μL of the target DNA, in only 45 minutes, for a device temperature of 65 °C and a reaction volume of 1.62 μL, one of the lowest volumes ever reported. Moreover, the electrophoretic analysis indicates that the amplification efficiency of the on-chip LAMP is considerably higher than that from the bench-top reaction

Passive Fault-Tolerance Management in Component-Based Embedded Systems

It is imperative to accept that failures can and will occur even in meticulously designed distributed systems and to design proper measures to counter those failures. Passive replication minimizes resource consumption by only activating redundant replicas in case of failures, as typically, providing and applying state updates is less resource demanding than requesting execution. However, most existing solutions for passive fault tolerance are usually designed and configured at design time, explicitly and statically identifying the most critical components and their number of replicas, lacking the needed flexibility to handle the runtime dynamics of distributed component-based embedded systems. This paper proposes a cost-effective adaptive fault tolerance solution with a significant lower overhead compared to a strict active redundancy-based approach, achieving a high error coverage with a minimum amount of redundancy. The activation of passive replicas is coordinated through a feedback-based coordination model that reduces the complexity of the needed interactions among components until a new collective global service solution is determined, hence improving the overall maintainability and robustness of the system

Control of a bidirectional DC-DC converter for grid-connected electric vehicles

Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáDue the increasing concerns about air pollution which contributes for the global warming growth, there is a vast dissemination of Electric Vehicle (EV) worldwide, considering that those vehicles are not polluting gases emitters and are pondered as clean means of transportation. With an increasing projection for those vehicles on next years, and due to the big amount of EV unities spread around the globe, numerous researches have been studying the utilization of those vehicles as a distributed energy storage system that, if connected with the electric grid, can provide many services for the power system. Hence, considering a promising future for EV and that the connection with the grid will be essential, studies concerning the interconnection between the electric network and the vehicles have been proved necessary. Therefore, the main objective of this thesis consists of developing a control technique for a Bidirectional DC-DC Converter (BDC), which is part of a bidirectional interface, that is responsible for connecting an EV battery with the grid. The bidirectional interface works with two operating modes, the Vehicle-to-Grid (V2G) mode - which can provide ancillary services for the utility grid, as the power supply - and the Grid-to-Vehicle (G2V) mode - which the main target is the battery charging process. The system has been validated not only by computational simulations, with Mathlab and Simulink softwares, but also experimentally, by using a realtime interface from dSPACE. The latter is in charge of interconnecting the power structure and the control algorithm developed on the Simulink environment. The experimental validation of the system was succesfully achieved.Devido às crescentes preocupações com a poluição do ar que contribui para o crescimento do aquecimento global, a disseminação dos veículos elétricos tem vindo a crescer por todo o mundo, por não emitirem gases poluentes, e sendo assim considerados como meios de transportes limpos. Com a projeção de crescimento destes veículos para os próximos anos, e graças à grande quantidade de unidades já em circulação, várias pesquisas estudam a utilização destes meios de transporte como unidades distribuídas de armazenamento de energia e que, quando ligados à rede elétrica podem fornecer vários serviços. Considerando então que o futuro é promissor para os veículos elétricos e que a integração dos mesmos com a rede será essencial, pesquisas quanto à interligação entre ambos tem-se mostrado necessárias. Com isso, o principal objetivo desta tese consiste em desenvolver uma técnica de controle para um conversor DC-DC bidirecional, que faz parte de uma interface bidirecional cujo o intuito é fazer a interligação entre a bateria de um veículo elétrico e a rede elétrica. O sistema conta com dois modos de funcionamento, o modo veículo para rede - (V2G) - que pode fornecer serviços auxiliares para a rede elétrica, como o fornecimento de potência, e o modo rede para o veículo - (G2V), cujo objetivo principal consiste no carregamento da bateria do veículo elétrico. A validação do sistema foi realizada computacionalmente com o auxílio dos programas MATLAB e Simulink e, em seguida, o sistema foi validado experimentalmente utilizando uma carta de controle em tempo real da dSPACE. Esta carta de controle é responsável por fazer a interligação entre a estrutura de potência e o controle desenvolvido em Simulink. A validação experimental do sistema foi realizada com sucesso

Automatic detection and resolution of deadlocks in Go programs

The Go programming language is acquiring momentum in the development of concurrent software. Even though Go supports the shared-memory model, the message-passing alternative is the favoured idiomatic approach. Naturally, this practice is not exempt of the usual difficulties: programs may deadlock and the language run-time has only very basic support for deadlock detection. Previous research on deadlock detection mainly focused on shared-memory concurrency models. For mainstream languages, tools and approaches specific to the message-passing paradigm are scarce and incipient. There is however a large body of work on models of concurrency that only recently started to be applied to languages like Go. Since the Go run-time lets many deadlocks pass unnoticed, and the existing solutions provided by third party tools detect many deadlocks but only try to fix a limited set of specific patterns, imposing severe conditions to do so, there is a clear need for more general deadlock resolution strategies, going beyond prevention and avoidance. To gain insight on real-world deadlock bugs, we first built and categorized a collection of bugs sourced from high-profile open-source Go projects. Next, we extended and implemented an algorithm that takes an abstraction of the communication behaviour of the program and, when all the communication operations on channels necessary for progress are present, but a deadlock is possible, presents the problem and offers a possible resolution for the error. The extensions allows our approach to analyse a much wider range of real world programs. We conclude with an evaluation, comparing with two other state-of-the-art solutions.A linguagem de programação Go tem ganhado tração no desenvolvimento de software concorrente. Apesar de o Go suportar o modelo de partilha de memória, o modelo alternativo de partilha de mensagens é a abordagem idiomática. Naturalmente, esta prática não está isenta das dificuldades usuais: os programas podem bloquear e o runtime da linguagem só possui um suporte muito básico para a deteção destes bloqueios. Investigação anterior na deteção de bloqueios focou principalmente no modelo de partilha de memória. Para linguagens convencionais, ferramentas e abordagens dedicadas ao paradigma de passagem de mensagens são escassas e incipientes. No entanto, existe um grande conjunto de trabalhos sobre modelos de concorrência que só recentemente começou a ser aplicado em linguagens como o Go. Visto que o run-time do Go deixa muitos bloqueios passar despercebidos e as soluções existentes detetam muitos bloqueios, mas só tentam resolver um conjunto muito pequeno de padrões. De modo a ganhar conhecimento sobre erros de bloqueio reais, nós começámos por construir e categorizar uma coleção de erros obtidos a partir de projetos Go open-source de alto perfil. De seguida, nós estendemos e implementámos um algoritmo que recebe uma abstração do comportamento da comunicação de um programa e quando todas as operações de comunicação nos canais necessários para o progresso estão presentes, mas um bloqueio é possível, apresenta o erro e oferece uma possível resolução do erro. A nossa extensão permite analisar um conjunto muito maior de programas reais. Concluímos com uma avaliação, comparando com duas outras soluções do estado da arte

Rotational Load Flow Method for Radial Distribution Systems

This paper introduces a modified edition of classical Cespedes' load flow method to radial distribution system analysis. In the developed approach, a distribution network is modeled in different complex reference systems and reduced to a set of connected equivalent subnetworks, each without resistance, while graph topology and node voltage solution are preserved. Active power losses are then not dissipated in the modeled subnetworks and active power flows can be obtained as a consequence of radiality. Thus, the proposed method preprocesses a series of variable transformations concomitant to an iterative algorithm using a forward-backward sweep to arrive at the load flow solution. The proposed approach has been tested using literature and actual distribution networks, and efficiency improvements are verified in comparison to Cespedes' load flow method

Evaluation of the Forward-Backward Sweep Load Flow Method using the Contraction Mapping Principle

This paper presents an assessment of the forward-backward sweep load flow method to distribution system analysis. The method is formally assessed using fixed-point concepts and the contraction mapping theorem. The existence and uniqueness of the load flow feasible solution is supported by an alternative argument from those obtained in the literature. Also, the closed-form of the convergence rate of the method is deduced and the convergence dependence of loading is assessed. Finally, boundaries for error values per iteration between iterates and feasible solution are obtained. Theoretical results have been tested in several numerical simulations, some of them presented in this paper, thus fostering discussions about applications and future works

Convergence Evaluation of a Load Flow Method based on Cespedes' Approach to Distribution System Analysis

This paper evaluates the convergence of a load flow method based on Cespedes' formulation to distribution system steady-state analysis. The method is described and the closed-form of its convergence rate is deduced. Furthermore, convergence dependence of loading and the consequences of choosing particular initial estimates are verified mathematically. All mathematical results have been tested in numerical simulations, some of them presented in the paper