Code offloading on real-time multimedia systems: a framework for handling code mobility and code offloading in a QoS aware environment

Actualmente, os smartphones e outros dispositivos móveis têm vindo a ser dotados com cada vez maior poder computacional, sendo capazes de executar um vasto conjunto de aplicações desde simples programas de para tirar notas até sofisticados programas de navegação. Porém, mesmo com a evolução do seu hardware, os actuais dispositivos móveis ainda não possuem as mesmas capacidades que os computadores de mesa ou portáteis. Uma possível solução para este problema é distribuir a aplicação, executando partes dela no dispositivo local e o resto em outros dispositivos ligados à rede. Adicionalmente, alguns tipos de aplicações como aplicações multimédia, jogos electrónicos ou aplicações de ambiente imersivos possuem requisitos em termos de Qualidade de Serviço, particularmente de tempo real. Ao longo desta tese é proposto um sistema de execução de código remota para sistemas distribuídos com restrições de tempo-real. A arquitectura proposta adapta-se a sistemas que necessitem de executar periodicamente e em paralelo mesmo conjunto de funções com garantias de tempo real, mesmo desconhecendo os tempos de execução das referidas funções. A plataforma proposta foi desenvolvida para sistemas móveis capazes de executar o Sistema Operativo Android.

Melhoria do processo de atendimento a clientes

Esta dissertação, que foi desenvolvida no seio da Divisão de Equipamento Industrial (DEI) da empresa Toyota Caetano Portugal, S.A. (TCAP), consiste na análise do processo de atendimento a clientes, a partir de uma investigação efectuada no escritório oficinal (EO) do sector Após-Venda Empilhadores (AVE). A recolha de dados, bem como o acompanhamento do processo de atendimento a clientes, têm como objectivo perceber quais as principais dificuldades do processo, para posteriormente ser definida a estratégia a utilizar no sentido de combater os pontos críticos do relacionamento com os clientes. Esta investigação permitiu identificar várias dificuldades no registo de pedidos de assistência, na pesquisa de informação e também no acesso aos dados pelo cliente. Assim, foi criado um protótipo informático com capacidade para dar resposta às deficiências identificadas. Foram analisados os requisitos necessários para o sistema de informação de suporte e transformado o processo de tratamento de dados (pedidos de assistência, pesquisas, acessos…), até aqui manual, num processo automático, inovador e acima de tudo funcional. Pretende-se desta forma, oferecer um serviço de confiança aos clientes gerando uma lealdade duradoura e acrescentar valor à empresa.

Assessment of data-driven modeling strategies for water delivery canals

The aim of this paper is to develop models for experimental open-channel water delivery systems and assess the use of three data-driven modeling tools toward that end. Water delivery canals are nonlinear dynamical systems and thus should be modeled to meet given operational requirements while capturing all relevant dynamics, including transport delays. Typically, the derivation of first principle models for open-channel systems is based on the use of Saint-Venant equations for shallow water, which is a time-consuming task and demands for specific expertise. The present paper proposes and assesses the use of three data-driven modeling tools: artificial neural networks, composite local linear models and fuzzy systems. The canal from Hydraulics and Canal Control Nucleus (A parts per thousand vora University, Portugal) will be used as a benchmark: The models are identified using data collected from the experimental facility, and then their performances are assessed based on suitable validation criterion. The performance of all models is compared among each other and against the experimental data to show the effectiveness of such tools to capture all significant dynamics within the canal system and, therefore, provide accurate nonlinear models that can be used for simulation or control. The models are available upon request to the authors.

QoS-based surrogates selection and service proposal formulation in offloading environments

Resource constraints are becoming a problem as many of the wireless mobile devices have increased generality. Our work tries to address this growing demand on resources and performance, by proposing the dynamic selection of neighbor nodes for cooperative service execution. This selection is in uenced by user's quality of service requirements expressed in his request, tailoring provided service to user's speci c needs. In this paper we improve our proposal's formulation algorithm with the ability to trade o time for the quality of the solution. At any given time, a complete solution for service execution exists, and the quality of that solution is expected to improve overtime.

On the adaptation of broadcast transactions in token-passing fieldbus networks with heterogeneous transmission media

Broadcast networks that are characterised by having different physical layers (PhL) demand some kind of traffic adaptation between segments, in order to avoid traffic congestion in linking devices. In many LANs, this problem is solved by the actual linking devices, which use some kind of flow control mechanism that either tell transmitting stations to pause (the transmission) or just discard frames. In this paper, we address the case of token-passing fieldbus networks operating in a broadcast fashion and involving message transactions over heterogeneous (wired or wireless) physical layers. For the addressed case, real-time and reliability requirements demand a different solution to the traffic adaptation problem. Our approach relies on the insertion of an appropriate idle time before a station issuing a request frame. In this way, we guarantee that the linking devices’ queues do not increase in a way that the timeliness properties of the overall system turn out to be unsuitable for the targeted applications.

Evaluating the duration of message transactions in broadcast wired/wireless fieldbus networks

Determining the response time of message transactions is one of the major concerns in the design of any distributed computer-controlled system. Such response time is mainly dependent on the medium access delay, the message length and the transmission delay. While the medium access delay in fieldbus networks has been thoroughly studied in the last few years, the transmission delay has been almost ignored as it is considered that it can be neglected when compared to the length of the message itself. Nevertheless, this assumption is no longer valid when considering the case of hybrid wired/wireless fieldbus networks, where the transmission delay through a series of different mediums can be several orders of magnitude longer than the length of the message itself. In this paper, we show how to compute the duration of message transactions in hybrid wired/wireless fieldbus networks. This duration is mainly dependent on the duration of the request and response frames and on the number and type of physical mediums that the frames must cross between initiator and responder. A case study of a hybrid wired/wireless fieldbus network is also presented, where it becomes clear the interest of the proposed approach

Provably good scheduling of sporadic tasks with resource sharing on a two-type heterogeneous multiprocessor platform

Consider the problem of scheduling a set of implicit-deadline sporadic tasks to meet all deadlines on a two-type heterogeneous multiprocessor platform where a task may request at most one of |R| shared resources. There are m1 processors of type-1 and m2 processors of type-2. Tasks may migrate only when requesting or releasing resources. We present a new algorithm, FF-3C-vpr, which offers a guarantee that if a task set is schedulable to meet deadlines by an optimal task assignment scheme that only allows tasks to migrate when requesting or releasing a resource, then FF-3Cvpr also meets deadlines if given processors 4+6*ceil(|R|/min(m1,m2)) times as fast. As far as we know, it is the first result for resource sharing on heterogeneous platforms with provable performance.

OPTIMAX 2014 - Radiation dose and image quality optimisation in medical imaging

Medical imaging is a powerful diagnostic tool. Consequently, the number of medical images taken has increased vastly over the past few decades. The most common medical imaging techniques use X-radiation as the primary investigative tool. The main limitation of using X-radiation is associated with the risk of developing cancers. Alongside this, technology has advanced and more centres now use CT scanners; these can incur significant radiation burdens compared with traditional X-ray imaging systems. The net effect is that the population radiation burden is rising steadily. Risk arising from X-radiation for diagnostic medical purposes needs minimising and one way to achieve this is through reducing radiation dose whilst optimising image quality. All ages are affected by risk from X-radiation however the increasing population age highlights the elderly as a new group that may require consideration. Of greatest concern are paediatric patients: firstly they are more sensitive to radiation; secondly their younger age means that the potential detriment to this group is greater. Containment of radiation exposure falls to a number of professionals within medical fields, from those who request imaging to those who produce the image. These staff are supported in their radiation protection role by engineers, physicists and technicians. It is important to realise that radiation protection is currently a major European focus of interest and minimum competence levels in radiation protection for radiographers have been defined through the integrated activities of the EU consortium called MEDRAPET. The outcomes of this project have been used by the European Federation of Radiographer Societies to describe the European Qualifications Framework levels for radiographers in radiation protection. Though variations exist between European countries radiographers and nuclear medicine technologists are normally the professional groups who are responsible for exposing screening populations and patients to X-radiation. As part of their training they learn fundamental principles of radiation protection and theoretical and practical approaches to dose minimisation. However dose minimisation is complex – it is not simply about reducing X-radiation without taking into account major contextual factors. These factors relate to the real world of clinical imaging and include the need to measure clinical image quality and lesion visibility when applying X-radiation dose reduction strategies. This requires the use of validated psychological and physics techniques to measure clinical image quality and lesion perceptibility.

Response time analysis of COTS-Based multicores considering the contention on the shared memory bus

The current industry trend is towards using Commercially available Off-The-Shelf (COTS) based multicores for developing real time embedded systems, as opposed to the usage of custom-made hardware. In typical implementation of such COTS-based multicores, multiple cores access the main memory via a shared bus. This often leads to contention on this shared channel, which results in an increase of the response time of the tasks. Analyzing this increased response time, considering the contention on the shared bus, is challenging on COTS-based systems mainly because bus arbitration protocols are often undocumented and the exact instants at which the shared bus is accessed by tasks are not explicitly controlled by the operating system scheduler; they are instead a result of cache misses. This paper makes three contributions towards analyzing tasks scheduled on COTS-based multicores. Firstly, we describe a method to model the memory access patterns of a task. Secondly, we apply this model to analyze the worst case response time for a set of tasks. Although the required parameters to obtain the request profile can be obtained by static analysis, we provide an alternative method to experimentally obtain them by using performance monitoring counters (PMCs). We also compare our work against an existing approach and show that our approach outperforms it by providing tighter upper-bound on the number of bus requests generated by a task.

Provably good multiprocessor scheduling with resource sharing

We present a 12(1 + 3R/(4m)) competitive algorithm for scheduling implicit-deadline sporadic tasks on a platform comprising m processors, where a task may request one of R shared resources.

An implicit GTS allocation mechanism in IEEE 802.15.4 for time-sensitive wireless sensor networks: theory and practice

Timeliness guarantee is an important feature of the recently standardized IEEE 802.15.4 protocol, turning it quite appealing for Wireless Sensor Network (WSN) applications under timing constraints. When operating in beacon-enabled mode, this protocol allows nodes with real-time requirements to allocate Guaranteed Time Slots (GTS) in the contention-free period. The protocol natively supports explicit GTS allocation, i.e. a node allocates a number of time slots in each superframe for exclusive use. The limitation of this explicit GTS allocation is that GTS resources may quickly disappear, since a maximum of seven GTSs can be allocated in each superframe, preventing other nodes to benefit from guaranteed service. Moreover, the GTS may be underutilized, resulting in wasted bandwidth. To overcome these limitations, this paper proposes i-GAME, an implicit GTS Allocation Mechanism in beacon-enabled IEEE 802.15.4 networks. The allocation is based on implicit GTS allocation requests, taking into account the traffic specifications and the delay requirements of the flows. The i-GAME approach enables the use of one GTS by multiple nodes, still guaranteeing that all their (delay, bandwidth) requirements are satisfied. For that purpose, we propose an admission control algorithm that enables to decide whether to accept a new GTS allocation request or not, based not only on the remaining time slots, but also on the traffic specifications of the flows, their delay requirements and the available bandwidth resources. We show that our approach improves the bandwidth utilization as compared to the native explicit allocation mechanism defined in the IEEE 802.15.4 standard. We also present some practical considerations for the implementation of i-GAME, ensuring backward compatibility with the IEEE 801.5.4 standard with only minor add-ons. Finally, an experimental evaluation on a real system that validates our theoretical analysis and demonstrates the implementation of i-GAME is also presented

Preliminary discussion on globally prioritized medium access for multi-channel wireless systems

We discuss the development of a simple globally prioritized multi-channel medium access control (MAC) protocol for wireless networks. This protocol provides “hard” pre-run-time real-time guarantees to sporadic message streams, exploits a very large fraction of the capacity of all channels for “hard” real-time traffic and also makes it possible to fully utilize the channels with non real-time traffic when hard real-time messages do not request to be transmitted. The potential of such protocols for real-time applications is discussed and a schedulability analysis is also presented.

i-GAME: an implicit GTS allocation mechanism in IEEE 802.15.4 for time-sensitive wireless sensor networks

The IEEE 802.15.4 Medium Access Control (MAC) protocol is an enabling technology for time sensitive wireless sensor networks thanks to its Guaranteed-Time Slot (GTS) mechanism in the beacon-enabled mode. However, the protocol only supports explicit GTS allocation, i.e. a node allocates a number of time slots in each superframe for exclusive use. The limitation of this explicit GTS allocation is that GTS resources may quickly disappear, since a maximum of seven GTSs can be allocated in each superframe, preventing other nodes to benefit from guaranteed service. Moreover, the GTSs may be only partially used, resulting in wasted bandwidth. To overcome these limitations, this paper proposes i-GAME, an implicit GTS Allocation Mechanism in beacon-enabled IEEE 802.15.4 networks. The allocation is based on implicit GTS allocation requests, taking into account the traffic specifications and the delay requirements of the flows. The i-GAME approach enables the use of a GTS by multiple nodes, while all their (delay, bandwidth) requirements are still satisfied. For that purpose, we propose an admission control algorithm that enables to decide whether to accept a new GTS allocation request or not, based not only on the remaining time slots, but also on the traffic specifications of the flows, their delay requirements and the available bandwidth resources. We show that our proposal improves the bandwidth utilization compared to the explicit allocation used in the IEEE 802.15.4 protocol standard. We also present some practical considerations for the implementation of i-GAME, ensuring backward compatibility with the IEEE 801.5.4 standard with only minor add-ons.

Relevância da assertividade na comunicação profissional de saúde-paciente

Actualmente existem evidências suficientes sobre os problemas de comunicação entre profissionais de saúde e pacientes e os benefícios de uma comunicação eficaz. Alguns autores chegam mesmo a considerar a comunicação como a ferramenta mais importante nos cuidados de saúde. Desde o início dos anos 90, as escolas médicas têm aumentado o interesse no ensino de competências comunicacionais; contudo, e não obstante este interesse crescente, a comunicação assertiva parece ser votada ao esquecimento. Na verdade, enquanto a assertividade tem recebido atenção crescente na literatura da Psicologia, os profissionais de saúde têm-se mostrado relutantes em aderir a esta área do saber, sendo os treinos assertivos para cuidadores ainda muito escassos. O objectivo deste trabalho é apresentar uma visão geral da assertividade e dos contributos desta para a comunicação eficaz dos profissionais de saúde com os pacientes e apontar seis temáticas específicas (por exemplo, lidar com reacções emocionais excessivas; elaborar pedidos) que devem integrar os treinos de comunicação para estudantes da área da saúde e profissionais de saúde.

Comparação do efeito da técnica de facilitação neuromuscular proprioceptiva com a técnica de músculo energia no alongamento muscular dos isquiotibiais a curto prazo

Introdução: A aplicação das técnicas de Contrair-Relaxar com Contracção do Antagonista (CRCA) e de Músculo Energia (TME) promovem um aumento da flexibilidade muscular, contudo poucos estudos comparam a eficácia de ambas. Apresentam aspectos comuns como a contracção prévia do músculo a alongar sendo esta máxima na CRCA e uma percentagem da máxima na TME. Contudo, alguma evidência sugere que não existe correspondência entre a força produzida e a desejada pelo que este aspecto da TME carece de explicação. Objectivos: Confirmar se a técnica CRCA e a TME são efectivas no alongamento muscular dos isquiotibiais a curto prazo, caso sejam determinar qual a mais efectiva. Pretende-se ainda avaliar se a percepção ao esforço durante a aplicação da TME corresponde à força efectivamente realizada. Métodos: Efectuou-se um estudo experimental com 45 voluntários distribuídos aleatoriamente pelos grupos CRCA, TME e Controlo. Avaliou-se a amplitude articular passiva de extensão do joelho antes e depois de aplicar as técnicas, utilizando um goniómetro. Nos participantes submetidos à TME avaliou-se a percepção ao esforço, solicitando uma contracção submáxima isométrica de 40% medida através do dinamómetro de mão. Resultados: Verificou-se um efeito das técnicas entre as avaliações (Teste ANOVA medidas repetidas factor tempo: p<0,001) e entre os grupos (tempo*grupo: p<0,001). Comparando os grupos dois a dois, verificaram-se diferenças entre o grupo CRCA e o grupo Controlo (Teste Post Hoc Games-Howell: p=0,001) e entre o grupo TME e o grupo Controlo (p=0,009), não existindo diferenças entre os grupos CRCA e TME (p=0,376). Os grupos CRCA e TME obtiveram um ganho de 10,7º e de 11,4º respectivamente, não havendo diferenças significativas entre os ganhos (Teste T-Student Independente: p=0,599). Existiram diferenças significativas entre os 40% CMVI produzida e desejada (Teste Wilcoxon: p=0,018). Conclusão: Ambas foram efectivas no aumento da flexibilidade muscular dos isquiotibiais a curto prazo. Os efeitos foram comparáveis, mas dada a menor complexidade e menor solicitação a TME foi considerada mais eficiente. A percepção ao esforço durante a aplicação da TME não correspondeu ao esforço desejado, existindo uma tendência para a produção de intensidades de contracções maiores.