IEEE C37.118-2 Synchrophasor Communication Framework

Synchrophasors have become an important part of the modern power system and numerous applications have been developed covering wide-area monitoring, protection and control. Most applications demand continuous transmission of synchrophasor data across large geographical areas and require an efficient communication framework. IEEE C37.118-2 evolved as one of the most successful synchrophasor communication standards and is widely adopted. However, it lacks a predefined security mechanism and is highly vulnerable to cyber attacks. This paper analyzes different types of cyber attacks on IEEE C37.118-2 communication system and evaluates their possible impact on any developed synchrophasor application. Further, the paper also recommends an efficent security mechanism that can provide strong protection against cyber attacks. Although, IEEE C37.118-2 has been widely adopted, there is no clear understanding of the requirements and limitations. To this aim, the paper also presents detailed performance evaluation of IEEE C37.118-2 implementations which could help determine required resources and network characteristics before designing any synchrophasor application.

Saving Energy by Delegating Network Activity to Home Gateways

Today, an ever-increasing number of devices has networking capability. The main implication of this fact is that such devices are often left fully powered yet idle just to maintain their network presence, hence leading to large energy waste. This ultimately results in higher electricity cost for consumers. This paper tackles an effective mechanism to reduce energy waste of consumer electronics, by boosting the usage of lowpower states available in most devices. The main concept is to delegate background networking routines to home gateways, which are today available in most homes and offices. The paper describes the functionality and the software architecture to be implemented by home gateways and consumer electronics, reports performance evaluation on a working prototype, and provides estimation of potential benefits for consumers.

Selective Multi-Carrier Index Keying OFDM: Error Propagation Rate with Moment Generating Function

We propose a new selective multi-carrier index keying in orthogonal frequency division multiplexing (OFDM) systems that opportunistically modulate both a small subset of sub-carriers and their indices. Particularly, we investigate the performance enhancement in two cases of error propagation sensitive and compromised deviceto-device (D2D) communications. For the performance evaluation, we focus on analyzing the error propagation probability (EPP) introducing the exact and upper bound expressions on the detection error probability, in the presence of both imperfect and perfect detection of active multi-carrier indices. The average EPP results in closedform are generalized for various fading distribution using the moment generating function, and our numerical results clearly show that the proposed approach is desirable for reliable and energy-efficient D2D applications.

A Low Complexity Detector with MRC Diversity Reception for MCIK-OFDM

Multi-carrier index keying (MCIK) is a recently developed transmission technique that exploits the sub-carrier indices as an additional degree of freedom for data transmission. This paper investigates the performance of a low complexity detection scheme with diversity reception for MCIK with orthogonal frequency division multiplexing (OFDM). For the performance evaluation, an exact and an approximate closed form expression for the pairwise error probability (PEP) of a greedy detector (GD) with maximal ratio combining (MRC) is derived. The presented results show that the performance of the GD is significantly improved when MRC diversity is employed. The proposed hybrid scheme is found to outperform maximum likelihood (ML) detection with a substantial reduction on the associated computational complexity.

Responsabilidade e governação na moderna gestão hospitalar

Esta dissertação, elaborada com vista à obtenção do grau de doutor pela Universidade de Aveiro, compõe-se de onze capítulos. O primeiro inclui, além de uma introdução, a justificação, os objectivos e a estrutura da dissertação. Seguem-se quatro capítulos relativos às empresas privadas onde são abordados, sucessivamente, as teorias da governação, a governação e gestão nas empresas, a regulação e a avaliação da performance, a avaliação da governação e da gestão de topo. O capítulo VI é dedicado à produção e avaliação na Administração Pública seguindo-se dois capítulos, um abordando a especificidade dos hospitais e da sua avaliação o outro caracterizando o hospital público português e a sua avaliação. No capítulo IX faz-se a síntese do que pode ser designado enquadramento teórico. No estudo empírico, capítulo X, definimos o problema, “Inexistência de modelo de avaliação dos conselhos de administração (CA) dos hospitais entidade pública empresarial”, descrevemos a metodologia seguida e os resultados obtidos, que se traduzem num modelo de avaliação dos CA. O modelo é constituído por três áreas – Resultados do hospital, Cumprimento da estratégia, Forma como o CA actuou e liderou – decompostas em critérios e indicadores, adequadamente ponderados, que permitem a valoração concreta de um qualquer CA de hospital EPE. Este modelo recolheu um consenso elevado dos principais peritos nacionais no tema que participaram nas técnicas de consenso usadas para a sua construção: um painel Delphi e três Técnicas de Grupo Nominal. Finalmente no capítulo XI extraímos as conclusões e referimos questões para investigação futura.

Wireless networks congestion control

Congestion control in wireless networks is an important and open issue. Previous research has proven the poor performance of the Transport Control Protocol (TCP) in such networks. The factors that contribute to the poor performance of TCP in wireless environments concern its unsuitability to identify/detect and react properly to network events, its TCP window based ow control algorithm that is not suitable for the wireless channel, and the congestion collapse due to mobility. New rate based mechanisms have been proposed to mitigate TCP performance in wired and wireless networks. However, these mechanisms also present poor performance, as they lack of suitable bandwidth estimation techniques for multi-hop wireless networks. It is thus important to improve congestion control performance in wireless networks, incorporating components that are suitable for wireless environments. A congestion control scheme which provides an e - cient and fair sharing of the underlying network capacity and available bandwidth among multiple competing applications is crucial to the definition of new e cient and fair congestion control schemes on wireless multi-hop networks. The Thesis is divided in three parts. First, we present a performance evaluation study of several congestion control protocols against TCP, in wireless mesh and ad-hoc networks. The obtained results show that rate based congestion control protocols need an eficient and accurate underlying available bandwidth estimation technique. The second part of the Thesis presents a new link capacity and available bandwidth estimation mechanism denoted as rt-Winf (real time wireless inference). The estimation is performed in real-time and without the need to intrusively inject packets in the network. Simulation results show that rt-Winf obtains the available bandwidth and capacity estimation with accuracy and without introducing overhead trafic in the network. The third part of the Thesis proposes the development of new congestion control mechanisms to address the congestion control problems of wireless networks. These congestion control mechanisms use cross layer information, obtained by rt-Winf, to accurately and eficiently estimate the available bandwidth and the path capacity over a wireless network path. Evaluation of these new proposed mechanisms, through ns-2 simulations, shows that the cooperation between rt-Winf and the congestion control algorithms is able to significantly increase congestion control eficiency and network performance.

Control design for multicast-aware class-based networks

The expectations of citizens from the Information Technologies (ITs) are increasing as the ITs have become integral part of our society, serving all kinds of activities whether professional, leisure, safety-critical applications or business. Hence, the limitations of the traditional network designs to provide innovative and enhanced services and applications motivated a consensus to integrate all services over packet switching infrastructures, using the Internet Protocol, so as to leverage flexible control and economical benefits in the Next Generation Networks (NGNs). However, the Internet is not capable of treating services differently while each service has its own requirements (e.g., Quality of Service - QoS). Therefore, the need for more evolved forms of communications has driven to radical changes of architectural and layering designs which demand appropriate solutions for service admission and network resources control. This Thesis addresses QoS and network control issues, aiming to improve overall control performance in current and future networks which classify services into classes. The Thesis is divided into three parts. In the first part, we propose two resource over-reservation algorithms, a Class-based bandwidth Over-Reservation (COR) and an Enhanced COR (ECOR). The over-reservation means reserving more bandwidth than a Class of Service (CoS) needs, so the QoS reservation signalling rate is reduced. COR and ECOR allow for dynamically defining over-reservation parameters for CoSs based on network interfaces resource conditions; they aim to reduce QoS signalling and related overhead without incurring CoS starvation or waste of bandwidth. ECOR differs from COR by allowing for optimizing control overhead minimization. Further, we propose a centralized control mechanism called Advanced Centralization Architecture (ACA), that uses a single state-full Control Decision Point (CDP) which maintains a good view of its underlying network topology and the related links resource statistics on real-time basis to control the overall network. It is very important to mention that, in this Thesis, we use multicast trees as the basis for session transport, not only for group communication purposes, but mainly to pin packets of a session mapped to a tree to follow the desired tree. Our simulation results prove a drastic reduction of QoS control signalling and the related overhead without QoS violation or waste of resources. Besides, we provide a generic-purpose analytical model to assess the impact of various parameters (e.g., link capacity, session dynamics, etc.) that generally challenge resource overprovisioning control. In the second part of this Thesis, we propose a decentralization control mechanism called Advanced Class-based resource OverpRovisioning (ACOR), that aims to achieve better scalability than the ACA approach. ACOR enables multiple CDPs, distributed at network edge, to cooperate and exchange appropriate control data (e.g., trees and bandwidth usage information) such that each CDP is able to maintain a good knowledge of the network topology and the related links resource statistics on real-time basis. From scalability perspective, ACOR cooperation is selective, meaning that control information is exchanged dynamically among only the CDPs which are concerned (correlated). Moreover, the synchronization is carried out through our proposed concept of Virtual Over-Provisioned Resource (VOPR), which is a share of over-reservations of each interface to each tree that uses the interface. Thus, each CDP can process several session requests over a tree without requiring synchronization between the correlated CDPs as long as the VOPR of the tree is not exhausted. Analytical and simulation results demonstrate that aggregate over-reservation control in decentralized scenarios keep low signalling without QoS violations or waste of resources. We also introduced a control signalling protocol called ACOR Protocol (ACOR-P) to support the centralization and decentralization designs in this Thesis. Further, we propose an Extended ACOR (E-ACOR) which aggregates the VOPR of all trees that originate at the same CDP, and more session requests can be processed without synchronization when compared with ACOR. In addition, E-ACOR introduces a mechanism to efficiently track network congestion information to prevent unnecessary synchronization during congestion time when VOPRs would exhaust upon every session request. The performance evaluation through analytical and simulation results proves the superiority of E-ACOR in minimizing overall control signalling overhead while keeping all advantages of ACOR, that is, without incurring QoS violations or waste of resources. The last part of this Thesis includes the Survivable ACOR (SACOR) proposal to support stable operations of the QoS and network control mechanisms in case of failures and recoveries (e.g., of links and nodes). The performance results show flexible survivability characterized by fast convergence time and differentiation of traffic re-routing under efficient resource utilization i.e. without wasting bandwidth. In summary, the QoS and architectural control mechanisms proposed in this Thesis provide efficient and scalable support for network control key sub-systems (e.g., QoS and resource control, traffic engineering, multicasting, etc.), and thus allow for optimizing network overall control performance.

Arte e educação : o papel das equipas criativas na mediação cultural

Relatório de estágio de mestrado, Ciências da Educação (Educação Intercultural), Universidade de Lisboa, Instituto de Educação, 2011

O e-portefólio como instrumento de avaliação de desempenho e veículo de partilha entre os professores do ensino básico

O tema da avaliação de desempenho dos professores continua a ser um tema muito presente no dia-a-dia de uma escola. O atual modelo de avaliação veio revolucionar o meio e acabou por trazer com ele o descontentamento dos professores. Face a este descontentamento, procurámos, investigar a exequibilidade de um novo instrumento de avaliação: o e-portefólio. Assim, o foco deste estudo de caso centra-se em estudar a praticabilidade da utilização de um instrumento de avaliação alternativo, o e-portfólio, enquanto instrumento de partilha entre os docentes e possível instrumento de avaliação de desempenho. Para o efeito desenvolvemos um estudo de natureza qualitativa, tendo realizado entrevistas semiestruturadas a um conjunto de professores do ensino básico, e posteriormente procedido à sua análise de conteúdo. Da análise e interpretação dos resultados concluímos que os docentes consideram que a partilha de materiais, através de e-portefólios, veio facilitar a vida dos professores e que estes assumem-se como um auxílio precioso e vantajoso no dia-a-dia dos docentes. Concluímos, também, que o e-portefólio poderá ser um possível instrumento de avaliação a adotar, desde que rigorosa e criteriosamente utilizado, uma vez que poderá estar bem visível parte do trabalho que os professores realizam. Os dados alertam, ainda, para a necessidade de uma reflexão, por parte da tutela, para a constante falta de tempo e excesso de burocracias mencionadas pelos professores.

Gestão estratégica: balanced scorecard para uma entidade hospitalar

Dissertação para obtenção do Grau de Mestre em Contabilidade e Finanças Orientador: Doutora Cláudia Maria Ferreira Pereira Lopes

A importância da auditoria interna e a avaliação do desempenho da organização: estudo de caso: empresas do sector do calçado

Dissertação de Mestrado apresentado ao Instituto de Contabilidade e Administração do Porto para a obtenção do grau de Mestre em Auditoria, sob orientação da Doutora Alcina Augusta de Sena Portugal Dias

A biosignal embedded system for physiological computing

Thesis submitted in the fulfilment of the requirements for the Degree of Master in Electronic and Telecomunications Engineering

On the development of an automatic voice pleasantness classification and intensity estimation system

In the last few years, the number of systems and devices that use voice based interaction has grown significantly. For a continued use of these systems, the interface must be reliable and pleasant in order to provide an optimal user experience. However there are currently very few studies that try to evaluate how pleasant is a voice from a perceptual point of view when the final application is a speech based interface. In this paper we present an objective definition for voice pleasantness based on the composition of a representative feature subset and a new automatic voice pleasantness classification and intensity estimation system. Our study is based on a database composed by European Portuguese female voices but the methodology can be extended to male voices or to other languages. In the objective performance evaluation the system achieved a 9.1% error rate for voice pleasantness classification and a 15.7% error rate for voice pleasantness intensity estimation.

Avaliação de desempenho docente e seus atores

Dissertação apresentada à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Supervisão em Educação

Energy efficient scheduling for cluster-tree wireless sensor networks with time-bounded data flows: application to IEEE 802.15.4/ZigBee

Cluster scheduling and collision avoidance are crucial issues in large-scale cluster-tree Wireless Sensor Networks (WSNs). The paper presents a methodology that provides a Time Division Cluster Scheduling (TDCS) mechanism based on the cyclic extension of RCPS/TC (Resource Constrained Project Scheduling with Temporal Constraints) problem for a cluster-tree WSN, assuming bounded communication errors. The objective is to meet all end-to-end deadlines of a predefined set of time-bounded data flows while minimizing the energy consumption of the nodes by setting the TDCS period as long as possible. Sinceeach cluster is active only once during the period, the end-to-end delay of a given flow may span over several periods when there are the flows with opposite direction. The scheduling tool enables system designers to efficiently configure all required parameters of the IEEE 802.15.4/ZigBee beaconenabled cluster-tree WSNs in the network design time. The performance evaluation of thescheduling tool shows that the problems with dozens of nodes can be solved while using optimal solvers.