Biotic and abiotic interactions in temporary summer pools of southern Portugal

In the south of Portugal, the summer season is characterized by reduced precipitation and high air temperatures, which causes the disruption of surface flow and subsequent formation of disconnect pools that may dry out entirely. During this dry period, there is a natural decrease of water quality standards due to the lack of water, leaving temporary rivers very vulnerable. Nevertheless, the remaining pools and surroundings become important in the survival of biological communities. Aquatic macroinvertebrates were sampled in several pools during the summer period (in the beginning and before the ending), in temporary tributaries of the Degebe River (Guadiana catchment), to quantify the response of macroinvertebrates communities to seasonal desiccation and habitat fragmentation. It we collected thousands individuals, representing 27 families of macroinvertebrates. Changes in the composition and abundance were affected by temporal variability in pool volume and location in the watershed. Smaller, upstream pools showed less diversity and abundance than downstream pools. Higher biological interactions and higher level of relationships with terrestrial ecosystems were perceptible for smaller summer pools. Pools were typically dominated by tolerant taxa such as midge larvae (Chironomidae), lesser boatman (Corixidae) and Oligochaeta, resulting in low diversity of communities over time. The results indicated the importance and impact of changes in habitat quality, size and connectivity in aquatic macroinvertebrates communities. They also revealed the importance of preservation and conservation of temporary ecosystems, particularly during the dry season, when the anthropogenic interference in ecosystems is more evident and can jeopardize the biodiversity maintenance of these systems

Energy efficient scheme based on simultaneous transmission of the local decisions in cooperative spectrum sensing

A common concern regarding cooperative spectrum sensing (CSS) schemes is the occupied bandwidth and the energy consumption during the transmissions of sensing information to the fusion center over the reporting control channels. This concern is intensified if the number of cooperating secondary users in the network is large. This article presents a new fusion strategy for a CSS scheme, aiming at increasing the energy efficiency of a recently proposed bandwidth-efficient fusion scheme. Analytical results and computational simulations unveil a high increase in energy efficiency when compared with the original approach, yet achieving better performances in some situations, and lower implementation complexity

Previsão do comportamento de redes de distribuição de água com métodos de aprendizagem automática

Water supply systems are indispensable infrastructures in any modern civilisation. Any modern house has running water at all time. People are so dependent on this essential good that today it is unthinkable for any social environment to live without water supply. Supply systems are responsible for maintaining the constant supply of water to homes, hospitals, industries, etc., and, consequently, are also responsible for maintaining the functioning of society. Since these systems are so indispensable in daily life, the costs associated with their operation are not taken into account. These systems have to pump water to meet their customers’ demands and face major energy cost-efficiency issues related to pumping operations. This work presents and analyses a possible solution to this problem using a decision support system that takes advantage of variations in the energy tariff throughout the day to optimise energy costs. It uses machine learning methods to predict future water demands and simulate the consequent behaviour of the networks, thus allowing the scheduling of pumping operations to coincide with the period when the tariff is cheaper. The results indicate that Artificial Neural Networks, Extreme Learning Machines and Recurrent Neural Networks with Gated Recurrent Units are capable of achieving a good performance forecasting water demands. It was also possible to create a model that accurately reproduces the behaviour of a water supply network of reasonable size using Artificial Neural Networks.Os sistemas de abastecimento de água são infraestruturas indispensáveis em qualquer civilização moderna. Qualquer casa moderna tem sempre água corrente. As pessoas estão de tal maneira dependentes deste bem essencial que hoje em dia é impensável qualquer meio social viver sem abastecimento de água. Os sistemas de abastecimento são responsáveis por manter o constante fornecimento de água a casas, hospitais, indústrias, etc., e, consequentemente, também são responsáveis por manter o funcionamento da sociedade. Como são sistemas indispensáveis no quotidiano não se tem tanto em consideração os custos associados com o seu funcionamento. Estes sistemas têm de bombear água para satisfazer os consumos dos seus clientes e enfrentam grandes problemas de custos energéticos relacionados com as operações de bombeamento. Este trabalho apresenta e analisa uma possível solução para este problema utilizando um sistema de apoio à decisão que tira partido da variação da tarifa energética ao longo do dia para fazer a otimização dos custos energéticos. A solução apresentada utiliza métodos de aprendizagem automática para prever consumos de água e simular o consequente comportamento das redes possibilitando assim o agendamento das operações de bombeamento para que coincidam com o período em que a tarifa é mais barata. Os resultados indicam que Redes Neuronais, Máquinas de Aprendizagem Extrema e Redes Neuronais Recurrentes com Gated Recurrent Units são capazes de alcançar um bom desempenho na previsão de consumos de água. Também foi possível criar um modelo que reproduz com precisão o comportamento de uma rede de abastecimento de água de médio tamanho usando Redes Neuronais.Mestrado em Engenharia Informátic

Determine the potential and the extent to which geographic socio-demographic data impacts retail performance revenue and consumer behavior and determine how much discounts impact revenue

Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Knowledge Management and Business IntelligenceThe objective of this thesis is to describe and analyze the sales and revenue of a food distribution company, Tasty and Sweet, by product or product type and relate it to geographic socio-demographic data provided by National Bureau of Statistics (INE). Tasty and Sweet operates and covers the entire Portuguese national territory, distributing and selling their products to any retailer company who is willing to resell them. The goal of this work is to develop an analytical model that allows the tracking of all the sales and revenue, by group item or by item, relating them, eventually, to the social and demographic characterization of a specific geography so that patterns may be (or not) identified. Another goal of the thesis is to determine the extent to which sales promotions have an impact on retailer sales. In order to achieve these objectives several methods of data analysis will be developed, supported and backed up by software from SAS Institute (Sas Guide and Sas Miner). It was possible to come to the following conclusions: firstly there are relevant socio-demographic variables that impact, or are more related, with de retailer’s revenue like: Indicators of enterprises by municipality N. º/km2 - enterprise density, 2016; Territorial structure by municipality - weight of resident population, 2011; Distribution of declared gross income less individual tax income paid of tax households by municipality (less 5k), 2016 are in fact more impacting; Secondly revenue volume is in fact impacted by discounts and promotions

Exploiting online services to enable anonymous and confidential messaging

Mestrado em Cibersegurança na Escola Superior de Tecnologia e Gestão do Instituto Politécnico de Viana do CasteloMessaging services are usually provided within social network platforms and allow these platforms to collect additional information about users, such as what time, for how long, with whom, and where a user communicates. This information enables user identification and is available to the messaging service provider even when communication is encrypted end-to-end. Thus, a gap still exists for alternative messaging services that enable anonymous and confidential communications and that are independent of a specific online service. Online services can still be used to support this messaging service, but in a way that enables users to communicate anonymously and without the knowledge and scrutiny of the online services. In this paper, we propose messaging using steganography and online services to support anonymous and confidential communication. In the proposed messaging service, only the sender and the receiver are aware of the existence of the exchanged data, even if the online services used or other third parties have access to the exchanged secret data containers. This work reviews the viability of using existing online services to support the proposed messaging service. Moreover, a prototype of the proposed message service is implemented and tested using two online services acting as proxies in the exchange of encrypted information disguised within images and links to those images. The obtained results confirm the viability of such a messaging service.Serviços de envio de mensagens instantâneos são normalmente fornecidos por plataformas de rede social e permitem que estas plataformas recolham informações adicionais sobre os utilizadores, como a que horas, por quanto tempo, com quem e onde um utilizador comunica. Esta informação permite a identificação do utilizador e está disponível para o prestador de serviços mesmo quando a comunicação é encriptada de ponta a ponta. Assim, existe ainda uma lacuna para serviços de mensagens alternativos que permitem comunicações anónimas e confidenciais e que são independentes de um serviço online específico. Os serviços online ainda podem ser utilizados para apoiar este serviço de mensagens, mas de uma forma que permite aos utilizadores comunicarem de forma anónima e sem o conhecimento e escrutínio dos serviços online. Neste artigo, propomos mensagens usando esteganografia e serviços online para apoiar comunicações anónimas e confidenciais. No serviço de mensagens proposto, apenas o remetente e o destinatário estão cientes da existência dos dados trocados, mesmo que os serviços online utilizados ou outros terceiros tenham acesso aos contentores de dados secretos trocados. Este trabalho revê a viabilidade de utilizar os serviços online existentes para apoiar o serviço de mensagens proposto. Além disso, um protótipo do serviço de mensagens proposto é implementado e testado usando dois serviços online agindo como proxies na troca de informações encriptadas escondidas dentro de imagens e links para essas imagens. Os resultados obtidos confirmam a viabilidade de tal solução

Intervention in Forte do Guincho Sea heritage – Conservation and architecture project

Forte do Guincho is situated on a promontory in a protected landscape. It was built in the 17th century and was part of an extensive line of defensive forts on the Cascais coast which protected the entrance to the Barra do Tejo. The particular nature of the location and the heritage value of Forte do Guincho were fundamental factors used in designing the architectural solution. Conservation and preservation are underlying concepts of the proposal. The pre-established use and programme intended to qualify the monument implied the need for a new construction, linked to the already existing structures but tectonically separated, thus potentially reversible, from the fort. The decision to plaster the walls of the fort or leave them unplastered was one of the most sensitive issues during the development of the project, since it would influence the integration of the fort in the landscape and its conservation. The aim of the (yet unbuilt) project was to achieve, through an integrated transdisciplinary project, a unity of form and materials between the pre-existing structures and the contemporary additions, thus giving renewed life to the monument while preserving its authenticity

Improved decision for a resource-efficient fusion scheme in cooperative spectrum sensing

Paper presented at at 2015 International Workshop on Telecommunications (IWT), 14th to 17th of June, Santa Rita do Sapucai, Brazil. Abstract Recently, a novel decision fusion scheme for cooperative spectrum sensing was proposed, aiming at saving resources in the reporting channel transmissions. Secondary users are allowed to report their local decisions through the symbols of binary modulations, at the same time and with the same carrier frequencies. As a consequence, the transmitted symbols add incoherently at the fusion center, forming a larger set of symbols in which a subset is associated to the presence of the primary signal, and another subset is associated to the absence of such a signal. A Bayesian decision criterion with uniform prior was applied for discriminating these subsets. In this paper we propose a modified decision rule in which the target probabilities of detection and false alarm are taken into account to produce a large performance improvement over the original decision criterion. This improvement comes with practically no cost in complexity and does not demand the knowledge of any additional information when compared to the original rule