Clustering an interval data set : are the main partitions similar to a priori partition?

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Evolução de software e serviços Web

A Internet causou uma revolução em grande parte dos processos das empresas, criando oportunidades e gerando necessidades até então desconhecidas. Os Sistemas de Informação, ferramentas indispensáveis para uma gestão moderna das actividades empresariais, também foram influenciados pela evolução constante da tecnologia e as facilidades oferecidas para a popularização do uso da Internet. Rumo a uma crescente necessidade de modernização, rapidez, agilidade, eficiência e eficácia que são exigidos das actividades da empresa, actualmente, a tecnologia da Web é exibida como uma opção viável para melhorar o desempenho na gestão da informação. Esta Tese procura dissertar acerca dos aspectos relativos ao funcionamento e implementação de Serviços Web, suas principais características, vantagens e desvantagens comparativamente aos sistemas de informação tradicionais. Os objectivos propostos podem ser sintetizados no conhecimento e descrição das funcionalidades dos Serviços Web, no estudo da situação actual, na identificação das características que potenciam a capacidade de evolução dos Serviços Web, no estudo e desempenho dos Serviços Web, e finalmente, no estudo e análise da especificação Segurança.

Increasing source to image distance for AP pelvis imaging: impact on radiation dose and image quality

Aim - A quantative primary study to determine whether increasing source to image distance (SID), with and without the use of automatic exposure control (AEC) for antero-posterior (AP) pelvis imaging, reduces dose whilst still producing an image of diagnostic quality. Methods - Using a computed radiography (CR) system, an anthropomorphic pelvic phantom was positioned for an AP examination using the table bucky. SID was initially set at 110 cm, with tube potential set at a constant 75 kVp, with two outer chambers selected and a fine focal spot of 0.6 mm. SID was then varied from 90 cm to 140 cm with two exposures made at each 5 cm interval, one using the AEC and another with a constant 16 mAs derived from the initial exposure. Effective dose (E) and entrance surface dose (ESD) were calculated for each acquisition. Seven experienced observers blindly graded image quality using a 5-point Likert scale and 2 Alternative Forced Choice software. Signal-to-Noise Ratio (SNR) was calculated for comparison. For each acquisition, femoral head diameter was also measured for magnification indication. Results - Results demonstrated that when increasing SID from 110 cm to 140 cm, both E and ESD reduced by 3.7% and 17.3% respectively when using AEC and 50.13% and 41.79% respectively, when the constant mAs was used. No significant statistical (T-test) difference (p = 0.967) between image quality was detected when increasing SID, with an intra-observer correlation of 0.77 (95% confidence level). SNR reduced slightly for both AEC (38%) and no AEC (36%) with increasing SID. Conclusion - For CR, increasing SID significantly reduces both E and ESD for AP pelvis imaging without adversely affecting image quality.

The effect of long-chain polyunsaturated fatty acids intake during pregnancy on adiposity of healthy full-term offspring at birth

Objective - The adjusted effect of long-chain polyunsaturated fatty acid (LCPUFA) intake during pregnancy on adiposity at birth of healthy full-term appropriate-for-gestational age neonates was evaluated. Study Design - In a cross-sectional convenience sample of 100 mother and infant dyads, LCPUFA intake during pregnancy was assessed by food frequency questionnaire with nutrient intake calculated using Food Processor Plus. Linear regression models for neonatal body composition measurements, assessed by air displacement plethysmography and anthropometry, were adjusted for maternal LCPUFA intakes, energy and macronutrient intakes, prepregnancy body mass index and gestational weight gain. Result - Positive associations between maternal docosahexaenoic acid intake and ponderal index in male offspring (β=0.165; 95% confidence interval (CI): 0.031–0.299; P=0.017), and between n-6:n-3 LCPUFA ratio intake and fat mass (β=0.021; 95% CI: 0.002–0.041; P=0.034) and percentage of fat mass (β=0.636; 95% CI: 0.125–1.147; P=0.016) in female offspring were found. Conclusion - Using a reliable validated method to assess body composition, adjusted positive associations between maternal docosahexaenoic acid intake and birth size in male offspring and between n-6:n-3 LCPUFA ratio intake and adiposity in female offspring were found, suggesting that maternal LCPUFA intake strongly influences fetal body composition.

Buying behavior and competition in the software market

In the actual world, the impact of the software buying decisions has a rising relevance in social and economic terms. This research tries to explain it focusing on the organizations buying decisions of Operating Systems and Office Suites for personal computers and the impact on the competition between incumbent and alternative players in the market in these software categories, although the research hypotheses and conclusions may extend to other software categories and platforms. We concluded that in this market beside brand image, product features or price, other factors could have influence in the buying choices. Network effect, switching costs, local network effect, lock-in or consumer heterogeneity all have influence in the buying decision, protecting the incumbent and making it difficult for the competitive alternatives, based mainly on product features and price, to gain market share to the incumbent. This happens in a stronger way in the Operating Systems category.

Influencing factors on the buying behavior in the software market

The case of desktop Operating System and Office Suite choices considering Proprietary and Open Source Software alternatives.

Sistema de Visão Stereo Ativo aplicado aos robôs do ISePorto

A presente dissertação endereça o desenvolvimento de um sistema de visão stereo ativo para os robôs de futebol robótico da equipa ISePorto do ISEP, de modo a que estes tirem o máximo partido das câmaras rotativas neles existentes. Este trabalho surge da necessidade de melhorar a capacidade de perceção do ambiente por parte dos robôs, principalmente da perceção da bola quando não está no plano do campo e dos robôs adversários. Esta necessidade surge devido ao aumento da dinâmica que se tem vindo a veri car ultimamente nas competições. Para tal, foram estudados algumas trabalhos relacionados no que diz respeito a sistemas de visão stereo com baselines variáveis e eixos de rotação em ambas as câmaras, bem como fundamentos de visão stereo. Foi proposta uma arquitetura para o sistema de visão ativo de modo a ser aplicado em qualquer robô da equipa MSL (Middle Size League). Para tornar possível a implementação desta arquitetura foi desenvolvido um procedimento para a calibração e determinação em tempo real dos parâmetros extrínsecos do par stereo em função da posição angular dos eixos rotativos do robô. O sistema de visão foi também dotado de capacidade de sincronismo e foram implementadas funcionalidades ao nível de software que possibilitam a deteção de objetos na imagem, a correspondência de objetos presentes nas imagens de ambas as câmaras e consequentemente a determinação das posições tridimensionais desses objetos relativamente ao robô. O sistema desenvolvido foi testado e validado em cenário MSL ao nível de perceção da bola, robôs adversários e linhas do campo. Os resultados obtidos apresentam uma melhoria signi cativa, face à implementação atual dos robôs, na perceção tridimensional da bola quando não está no plano do campo, e dos robôs adversários.

On the hardware and software architecture of the robuter mobile platform: a hands-on approach

The Robuter is a robotic mobile platform that is located in the “Hands-On” Laboratory of the IPP-Hurray! Research Group, at the School of Engineering of the Polytechnic Institute of Porto. Recently, the Robuter was subject of an upgrading process addressing two essential areas: the Hardware Architecture and the Software Architecture. This upgrade in process was triggered due to technical problems on-board of the robot and also to the fact that the hardware/software architecture has become obsolete. This Technical Report overviews the most important aspects of the new Hardware and Software Architectures of the Robuter. This document also presents a first approach on the first steps towards the use of the Robuter platform, and provides some hints on future work that may be carried out using this mobile platform.

Proposta de metodologia para avaliação de software comercial destinado ao projeto de engenharia da construção

A partir da década de noventa do século passado, começaram a surgir no mercado ferramentas de cálculo com o objetivo de agilizar a conceção do projeto de engenharia da construção. Até ao final da década de setenta os computadores existentes eram enormes, apenas entidades de grande poder económico os podiam adquirir. Na década de oitenta surgiu no mercado o PC, Personal Computer, estas pequenas máquinas começaram a ser adquiridas pela generalidade das empresas e em Portugal no final desta década era possível encontrar indivíduos que já possuíam o seu PC. Na década de noventa, a saída de recém-formados das instituições de ensino superior, fomentou no mercado o aparecimento de empresas de informática dedicadas à conceção de software de acordo com as necessidades do próprio mercado, daí resultando software comercial à medida e software comercial de prateleira (COTS, Commercial Off-The-Shelf)). O software comercial, ao ser utilizado por um grande número de pessoas, atingindo facilmente, no caso do COTS, os milhares, tem condições para evoluir de acordo com as exigências sistemáticas do próprio mercado, atingindo elevados patamares no cumprimento de requisitos de qualidade, nomeadamente no que concerne à funcionalidade, fiabilidade, usabilidade, manutenibilidade, eficiência, portabilidade e qualidade na utilização. A utilização de software comercial na área do projeto de engenharia da construção é hoje em dia uma prática absolutamente generalizada. A seleção do software pode tornar-se um processo complexo especialmente naquelas áreas em que existe grande oferta. A utilização de critérios de avaliação bem definidos poderá agilizar o processo e dar maiores garantias no momento da decisão final. Neste documento apresenta-se uma proposta de metodologia para avaliação e comparação de softwares.

Specification of software architecture reconfiguration

In the past years, Software Architecture has attracted increased attention by academia and industry as the unifying concept to structure the design of complex systems. One particular research area deals with the possibility of reconfiguring architectures to adapt the systems they describe to new requirements. Reconfiguration amounts to adding and removing components and connections, and may have to occur without stopping the execution of the system being reconfigured. This work contributes to the formal description of such a process. Taking as a premise that a single formalism hardly ever satisfies all requirements in every situation, we present three approaches, each one with its own assumptions about the systems it can be applied to and with different advantages and disadvantages. Each approach is based on work of other researchers and has the aesthetic concern of changing as little as possible the original formalism, keeping its spirit. The first approach shows how a given reconfiguration can be specified in the same manner as the system it is applied to and in a way to be efficiently executed. The second approach explores the Chemical Abstract Machine, a formalism for rewriting multisets of terms, to describe architectures, computations, and reconfigurations in a uniform way. The last approach uses a UNITY-like parallel programming design language to describe computations, represents architectures by diagrams in the sense of Category Theory, and specifies reconfigurations by graph transformation rules.

EMMON - EMbedded MONitoring

Despite the steady increase in experimental deployments, most of research work on WSNs has focused only on communication protocols and algorithms, with a clear lack of effective, feasible and usable system architectures, integrated in a modular platform able to address both functional and non–functional requirements. In this paper, we outline EMMON [1], a full WSN-based system architecture for large–scale, dense and real–time embedded monitoring [3] applications. EMMON provides a hierarchical communication architecture together with integrated middleware and command and control software. Then, EM-Set, the EMMON engineering toolset will be presented. EM-Set includes a network deployment planning, worst–case analysis and dimensioning, protocol simulation and automatic remote programming and hardware testing tools. This toolset was crucial for the development of EMMON which was designed to use standard commercially available technologies, while maintaining as much flexibility as possible to meet specific applications requirements. Finally, the EMMON architecture has been validated through extensive simulation and experimental evaluation, including a 300+ nodes testbed.

Software transactional memory as a building block for parallel embedded realtime systems

The recent trends of chip architectures with higher number of heterogeneous cores, and non-uniform memory/non-coherent caches, brings renewed attention to the use of Software Transactional Memory (STM) as a fundamental building block for developing parallel applications. Nevertheless, although STM promises to ease concurrent and parallel software development, it relies on the possibility of aborting conflicting transactions to maintain data consistency, which impacts on the responsiveness and timing guarantees required by embedded real-time systems. In these systems, contention delays must be (efficiently) limited so that the response times of tasks executing transactions are upper-bounded and task sets can be feasibly scheduled. In this paper we assess the use of STM in the development of embedded real-time software, defending that the amount of contention can be reduced if read-only transactions access recent consistent data snapshots, progressing in a wait-free manner. We show how the required number of versions of a shared object can be calculated for a set of tasks. We also outline an algorithm to manage conflicts between update transactions that prevents starvation.

Poster: EMMON: a WSN system architecture and toolset for large-scale and dense real-time embedded monitoring

Wireless sensor networks (WSNs) have attracted growing interest in the last decade as an infrastructure to support a diversity of ubiquitous computing and cyber-physical systems. However, most research work has focused on protocols or on specific applications. As a result, there remains a clear lack of effective and usable WSN system architectures that address both functional and non-functional requirements in an integrated fashion. This poster outlines the EMMON system architecture for large-scale, dense, real-time embedded monitoring. It provides a hierarchical communication architecture together with integrated middleware and command and control software. It has been designed to maintain as much as flexibility as possible while meeting specific applications requirements. EMMON has been validated through extensive analytical, simulation and experimental evaluations, including through a 300+ nodes test-bed the largest single-site WSN test-bed in Europe.

EMMON: a WSN system architecture for large scale and dense real-time embedded monitoring

Wireless sensor networks (WSNs) have attracted growing interest in the last decade as an infrastructure to support a diversity of ubiquitous computing and cyber-physical systems. However, most research work has focused on protocols or on specific applications. As a result, there remains a clear lack of effective, feasible and usable system architectures that address both functional and non-functional requirements in an integrated fashion. In this paper, we outline the EMMON system architecture for large-scale, dense, real-time embedded monitoring. EMMON provides a hierarchical communication architecture together with integrated middleware and command and control software. It has been designed to use standard commercially-available technologies, while maintaining as much flexibility as possible to meet specific applications requirements. The EMMON architecture has been validated through extensive simulation and experimental evaluation, including a 300+ node test-bed, which is, to the best of our knowledge, the largest single-site WSN test-bed in Europe to date.

Managing contention of software transactional memory in real-time systems

The foreseen evolution of chip architectures to higher number of, heterogeneous, cores, with non-uniform memory and non-coherent caches, brings renewed attention to the use of Software Transactional Memory (STM) as an alternative to lock-based synchronisation. However, STM relies on the possibility of aborting conflicting transactions to maintain data consistency, which impacts on the responsiveness and timing guarantees required by real-time systems. In these systems, contention delays must be (efficiently) limited so that the response times of tasks executing transactions are upperbounded and task sets can be feasibly scheduled. In this paper we defend the role of the transaction contention manager to reduce the number of transaction retries and to help the real-time scheduler assuring schedulability. For such purpose, the contention management policy should be aware of on-line scheduling information.