Amostragem multi-adaptativa de tráfego de rede

http://crc2011.uc.pt/A monitorização eficiente de redes e serviços tem um papel crucial no suporte à gestão e engenharia das redes de comunicações atuais. Obter uma visão realista do estado da rede sem, no entanto, interferir na sua operação normal é essencial no suporte à decisão dos operadores de redes e dos sistemas auto-configuráveis. Neste sentido, as técnicas de amostragem de tráfego procuram reduzir o impacto da monitorização no funcionamento da rede, mantendo a acurácia na estimação de parâmetros referentes ao seu comportamento estatístico. Embora seja observada uma evolução das atuais técnicas na correta estimação do desempenho da rede, o overhead associado ao volume de dados envolvidos nos processos de amostragem de tráfego ainda é considerável. Neste contexto, este trabalho propõe uma nova técnica de amostragem multi-adaptativa de tráfego, baseada em predição linear, que tem por objetivo reduzir significativamente o volume total de dados envolvidos na monitorização do estado da rede, sem comprometer a representatividade das amostras na estimação dos parâmetros em análise. A avaliação desta proposta, com base em coletas de tráfego real, demonstra que é possível reduzir significativamente o volume de dados analisado e mesmo assim alcançar, em vários parâmetros de caracterização, resultados mais precisos que as técnicas classicamente utilizadas

Data security and trustworthiness in online public services: An assessment of Portuguese institutions

Providing public services through the internet is an effective approach towards an encompassing number of citizens being covered by them and for cost reduction. However, the fast development of this area has fostered discussion and legislation regarding information security and trustworthiness. In addition to security mechanisms for data processed and stored internally, service providers must ensure that data exchanged between their servers and citizens are not intercepted or modified when traversing heterogeneous and uncontrolled networks. Moreover, such institutions should provide means enabling the citizen to verify the authenticity of the services offered. In this way, the present work provides a comprehensive overview regarding the security posture of Portuguese public institutions in their online services. It consists of non-invasive robustness evaluation of the deployed solutions for end-to-end data encryption and the correct use of digital certificates. As a result, we provide some recommendations aiming to enhance the current panorama in the majority of the 111 online services considered in this study.This paper is a result of the project SmartEGOV: Harnessing EGOV for Smart Governance (Foundations, Methods, Tools) NORTE-01-0145-FEDER-000037, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (EFDR)

Classificação multinível de tráfego de rede com base em amostragem

A classificação e a caracterização do tráfego de rede são tarefas essenciais para o correto planeamento e gestão das actuais redes de comunicações. No entanto, face ao elevado volume de tráfego envolvido, essas tarefas podem beneficiar largamente do recurso a tráfego amostrado, desde que este permita obter uma visão da rede realista através de pequenas porções de tráfego. Neste contexto, este artigo tem como principal objetivo a exploração e comparação da acurácia de diferentes estratégias de classificação de tráfego de rede quando conjugadas com diferentes técnicas de amostragem. Recorrendo à ferramenta TIE - Traffic Identification Engine [1], que disponibiliza estratégias de classificação de tráfego operando em distintos níveis da pilha protocolar, e a uma framework de amostragem que implementa técnicas clássicas e emergentes de amostragem de tráfego [2], é analisado o impacto da estratégia de classificação e amostragem na correta identificação dos fluxos de rede. A base dos testes realizados recorre a tráfego de rede real coletado no Instituto Nacional de Estatística, posteriormente submetido a diferentes estratégias de classificação e amostragem. Desta forma, pretende- se contribuir com diretivas para a obtenção de uma classificação realista do tráfego de rede com o menor overhead em termos de tráfego coletado e analisado.Este trabalho é suportado pela FCT - Fundação para a Ciência e Tecnologia no âmbito do projeto UID/CEC/00319/2013.info:eu-repo/semantics/publishedVersio

Short-term wind forecasting for energy resources scheduling

This paper proposes a wind power forecasting methodology based on two methods: direct wind power forecasting and wind speed forecasting in the first phase followed by wind power forecasting using turbines characteristics and the aforementioned wind speed forecast. The proposed forecasting methodology aims to support the operation in the scope of the intraday resources scheduling model, namely with a time horizon of 5 minutes. This intraday model supports distribution network operators in the short-term scheduling problem, in the smart grid context. A case study using a real database of 12 months recorded from a Portuguese wind power farm was used. The results show that the straightforward methodology can be applied in the intraday model with high wind speed and wind power accuracy. The wind power forecast direct method shows better performance than wind power forecast using turbine characteristics and wind speed forecast obtained in first phase

Enhancing traffic sampling scope and efficiency

Traffic Sampling is a crucial step towards scalable network measurements, enclosing manifold challenges. The wide variety of foreseeable sampling scenarios demands for a modular view of sampling components and features, grounded on a consistent architecture. Articulating the measurement scope, the required information model and the adequate sampling strategy is a major design issue for achieving an encompassing and efficient sampling solution. This is the main focus of the present work, where a layered architecture, a taxonomy of existing sampling techniques distinguishing their inner characteristics and a flexible framework able to combine these characteristics are introduced. In addition, a new multiadaptive technique proposal, based on linear prediction, allows to reduce the measurement overhead significantly, while assuring that traffic samples reflect the statistical behavior of the global traffic under analysis.Fundação para a Ciência e a Tecnologia (FCT

Optimized robot strategy, ball filters and new referee whistle hardware filter

This paper briefly describes the main changes on the Minho Team robots since the last RoboCup edition. Work has been carried out on the robots in order to constantly improve their capabilities, based on the experience from previous participations. The main topics to deal in this paper are related with the optimization of movement on the field and also game strategy software, a ball filter recently implemented on the robots in order to follow only the correct ball. Also on this paper a description of the whole software implementation is made by describing the main Algorithm. A new referee whistle hardware filter has been developed in the last year and is here described its electronics

A modular traffic sampling architecture for flexible network measurements

Dissertação de Mestrado (Programa Doutoral em Informática)The massive traffic volumes and the heterogeneity of services in today’s networks urge for flexible, yet simple measurement solutions to assist network management tasks, without impairing network performance. To turn treatable tasks requiring traffic analysis, sampling the traffic has become mandatory, triggering substantial research in the area. In fact, multiple sampling techniques have been proposed to assist network engineering tasks, each one targeting specific measurement goals and traffic scenarios. Despite that, there is still a lack of an encompassing solution able to support the flexible deployment of these techniques in production networks. In this context, this research work proposes a modular traffic sampling architecture able to foster the flexible design and deployment of efficient measurement strategies. The architecture is composed of three layers i.e., management plane, control plane and data plane covering key components to achieve versatile and lightweight measurements in diverse traffic scenarios and measurement activities. The flexibility and modularity in deploying different sampling strategies relies upon a novel taxonomy of sampling techniques, in which, current and emerging techniques are identified regarding their inner characteristics - granularity, selection trigger and selection scheme. Following the proposed taxonomy, a sampling framework prototype has been developed and used as an experimental implementation of the proposed architecture, providing a fair environment to assess and compare sampling techniques under distinct measurement scenarios. Supported by the sampling framework, distinct techniques have been evaluated regarding their performance in balancing the computational burden and the accuracy in supporting traffic workload estimation and flow analysis. The results have demonstrated the relevance and applicability of the proposed architecture, revealing that a modular and configurable approach to sampling is a step forward for improving sampling scope and efficiency.Os grandes volumes de tráfego e a heterogeneidade de serviços nas redes atuais requerem soluções de medição que sejam flexíveis e simples de modo a sustentar as tarefas de gestão de redes sem afetar o desempenho das mesmas. Para tornar tratável as tarefas que exigem análise de tráfego, tornou-se obrigatório recorrer a amostragem do tráfego, motivando uma investigação substancial na área. Como consequência, várias técnicas de amostragem foram propostas para auxiliar as tarefas de engenharia de redes, cada uma orientada a satisfazer objetivos de medição e cenários de tráfego específicos. Apesar disso, ainda não existe uma solução abrangente capaz de suportar a implantação flexível destas técnicas em redes de produção. Neste contexto, este trabalho propõe uma arquitetura modular de amostragem de tráfego capaz de fomentar a concepção flexível e a implementação de estratégias efi- cientes de medição de tráfego. A arquitetura é composta por três camadas, nomeadamente, camada de gestão, camada de controle e camada de dados, cobrindo os principais componentes para alcançar versatilidade e baixo custo computacional em variados cenários de tráfego e atividades de medição. A flexibilidade e modularidade na implementação de diferentes técnicas de amostragem baseia-se numa nova taxonomia, na qual técnicas atuais e emergentes são identificadas de acordo com suas características internas - granularidade, trigger de seleção e esquema de seleção. Seguindo a taxonomia proposta, um protótipo estruturando e agregando as diferentes técnicas de amostragem foi desenvolvido e utilizado na implementação experimental da arquitetura, permitindo avaliar e comparar as técnicas de amostragem em diversos cenários de medição. Suportado pelo protótipo desenvolvido, distintas técnicas foram avaliadas quanto ao seu desempenho em equilibrar a carga computacional e a acurácia na estimação do volume de tráfego e na análise de fluxos. Os resultados demonstraram a relevância e aplicabilidade da arquitetura de amostragem proposta, revelando que uma abordagem modular e configurável constitui um avanço no sentido de melhorar a eficiência na amostragem de tráfego

Pharmacological potential of methylxanthines: Retrospective analysis and future expectations

Methylated xanthines (methylxanthines) are available from a significant number of different botanical species. They are ordinarily included in daily diet, in many extremely common beverages and foods. Caffeine, theophylline and theobromine are the main methylxanthines available from natural sources. The supposedly relatively low toxicity of methylxanthines, combined with the many beneficial effects that have been attributed to these compounds through time, generated a justified attention and a very prolific ground for dedicated scientific reports. Methylxanthines have been widely used as therapeutical tools, in an intriguing range of medicinal scopes. In fact, methylxanthines have been/were medically used as Central Nervous System stimulants, bronchodilators, coronary dilators, diuretics and anti-cancer adjuvant treatments. Other than these applications, methylxanthines have also been hinted to hold other beneficial health effects, namely regarding neurodegenerative diseases, cardioprotection, diabetes and fertility. However, it seems now consensual that toxicity concerns related to methylxanthine consumption and/or therapeutic use should not be dismissed. Taking all the knowledge and expectations on the potential of methylxanthines into account, we propose a systematic look at the past and future of methylxanthine pharmacologic applications, discussing all the promise and anticipating possible constraints. Anyways, methylxanthines will still substantiate considerable meaningful research and discussion for years to come.info:eu-repo/semantics/publishedVersio

The effects of the invasive seaweed asparagopsis armata on native rock pool communities: evidences from experimental exclusion

Biological invasions represent a threat to ecosystems, through competition and habitat destruction, which may result in significant changes of the invaded community. Asparagopsis armata Harvey 1855 is a red macroalgae (Rodophyta) globally recognized as an invasive species. It is found from the intertidal to shallow subtidal areas, on rock or epiphytic, forming natural vegetation belts on exposed coasts. This study evaluated the variations on native intertidal seaweed and macroinvertebrate assemblages inhabiting rock pools with and without the presence of the invasive macroalgae A. armata. To achieve this, manipulation experiments on Atlantic (Portugal) rock pools were done. Three rock pools were maintained without A. armata by manual removal of macroalgae, and three others were not experimentally manipulated during the study period and A. armata was freely present. In this study the variations between different rock pools were assessed. Results showed different patterns in the macroalgae composition of assemblages but not for the macrobenthic communities. Ellisolandia elongata (J. Ellis & Solander) K.R. Hind & G.W. Saunders 2013 was the main algal species affected by the invasion of A. armata. Invaded pools tended to show less macroalgal species richness, showing a more constant and conservative structure, with lower variation of its taxonomic composition than the pools not containing A. armata, where the variability between samples was always higher. Despite the importance of the achieved results, further data based on observation of long-term series are needed, in order to further understand more severe effects of the invader A. armata on native macroalgal assemblage.info:eu-repo/semantics/publishedVersio