Water losses reduction in Water Distribution Systems (WDS) is nowadays an issue of growing importance for water companies to ensure the sustainability of these public services. In this context, the implementation of District Metered Areas (DMAs) and/or pressure management are considered the most effective tools for leakage control, particularly in large networks and in systems with deteriorated infrastructures and with high pressure. Based in previous studies performed by the authors [1,2,3], the methodology described in this paper follows the ‘water losses management international best practices’ and makes it possible to evaluate the Net Present Value (NPV) of DMAs project, as well as the benefits that can be achieved by pressure management in WDS, particularly in terms of water production reduction. It is based on the analysis of the minimum night flow and the FAVAD concept, and it uses a pressure driven simulation model to predict the network hydraulic behaviour under different pressure conditions. Leakage assessment is performed using pressure driven analysis and the optimal location of pipes reinforcement/replacement and settings of the Pressure Reduction Valves (PRVs) are identified by a Simulated Annealing algorithm. The potential of this methodology is illustrated through an hypothetical case study.

Water losses reduction in Water Distribution Systems (WDSs) is nowadays an issue of growing importance for water companies to ensure the economic sustainability of these public services. In this context, the implementation of District Metered Areas (DMAs) and/or pressure management are considered effective tools for leakage control, particularly in large networks and in systems with deteriorated infrastructures and with high pressure. Based in previous studies performed by the authors (Gomes et al., 2012; Gomes et al., 2015; Sousa et al., 2015), the methodology described in this paper follows the ‘water losses management international best practices’ and makes it possible to evaluate the Net Present Value (NPV) of DMAs project, as well as the benefits that can be achieved by pressure management in WDS, particularly in terms of water production reduction. Leakage assessment is performed using the analysis of the minimum night flow and the FAVAD concept, and it uses a pressure driven simulation model to predict the network hydraulic behaviour under different pressure conditions. The optimal location of DMAs entry points, pipes reinforcement/replacement and locations/settings of the Pressure Reduction Valves (PRVs) are identified by a Simulated Annealing algorithm. The potential of this methodology is illustrated through an hypothetical case study.

O evangelho de Tomé tem sido lido e relido ao longo dos séculos, as leituras têm sido literais, figurativas ou simbólicas. Desde os seus primórdios este texto apresenta-se ao seu leitor envolto numa aura de mistério e enigma com mensagens por desvelar e significados por desvendar. No âmbito do mestrado de História e Cultura das Religiões foi desenvolvido um esforço de investigação que terá como objetivo situar as vivências e mentalidades do evangelho de Tomé. Vivências estas diretamente associadas ao desenvolvimento do cristianismo primitivo no espaço geográfico da Síria oriental nomeadamente em Edessa. Esta investigação procura responder às seguintes questões: qual foi o contexto histórico deste evangelho, o seu espaço social, os seus vínculos sociais e as suas vivências e mentalidades; qual é o núcleo da sua mensagem e quais são as caraterísticas específicas da linguagem e da experiência no cristianismo primitivo de Edessa a leste do Eufrates. Espera-se assim dar um contributo à compreensão histórica do desenvolvimento do espaço mental cristão no primeiro século. O evangelho de Tomé, em especial a sua cristologia e antropologia, forma uma nova perspetiva a partir da qual será possível observar as origens do movimento cristão e a forma como a figura de Jesus foi retratada nos diferentes contextos sociais e espaços geográficos do mundo antigo.

Water loss is a big challenge for water supply companies worldwide, and the Water Network Partitioning (WNP) is an excellent tool for water loss management–particularly in the current difficult economic and financial conditions. WNP is a recent research line and consists in dividing the water distribution network into smaller zones called District Metered Areas (DMAs) with one (or more, in exceptional cases) supply point, to reduce the network complexity and/or allow pressure management. Since there are several possible future scenarios, such as the water demand and/or the infrastructure degradation forecasts, which may have different impacts on the hydraulic behaviour, in this paper a computational application, based on an optimization model, is proposed to achieve a compromise between robustness required for the DMAs design (using a baseline scenario) and different decision makers’ options (using other scenarios with a lower “probability” of occurrence), to reduce the total cost. The objective function reflects the minimization of the squared deviations between the total cost of the DMAs design and the minimum cost for each scenario forecasted for the project plan, multiplied by the weight or “probability” of occurrence for each of the scenarios. The performance of the computational application is illustrated with a case study, and the results are encouraging.

In this paper the influence of several factors to establish a suitable DMA design is considered using an adaptation of the methodology previously developed by Gomes [1]. This methodology is based on graph theory concepts (Floyd-Warshall algorithm) and some user-defined criteria to establish the number and size of DMAs and uses a Simulated Annealing algorithm to identify the most appropriate number and location of metering stations, boundary valves and network reinforcement/replacement needs along the project plan. Different design criteria are applied to a case study and the results obtained by the methodology are used to draw some conclusions. © 2015 The Authors.

A redução das perdas em sistema de distribuição de água, até níveis considerados economicamente viáveis e tecnicamente aceitáveis, constitui um dos principais objectivos para a maior parte das Entidades Gestoras de serviços públicos de abastecimento de água, tendo em vista alcançar a médio e longo prazo a sustentabilidade do serviço prestado. Esta realidade tem vindo a ser evocada a nível internacional, e, em Portugal, está consagrada no PEAASAR 2007-2013, que fixa a necessidade de reduzir as perdas de água para valores inferiores a 20% (Objectivo operacional 2). Neste contexto, a implementação de Zonas de Medição e Controlo (ZMC), sectorização do sistema em subsistemas de menor dimensão, pode dar um excelente contributo para atingir esses objectivos. Embora a sectorização da rede não permita directamente o controlo das perdas, acaba por ser um instrumento crucial no que concerne à sua detecção, caracterização e distribuição espacial. Além disso, facilita a implementação de estratégias activas de controlo de perdas, o estabelecimento de prioridades de intervenção na rede, a gestão das pressões ao longo do dia em função dos consumos, o controlo da facturação e monitorização de parâmetros relacionados com a qualidade da água. Partindo deste pressuposto, duas novas metodologias são propostas neste trabalho como ferramentas de gestão e exploração de sistemas de distribuição de água. Sabendo que a ocorrência de perdas de água, na sua grande maioria, ocorre na rede de distribuição nos ramais de ligação, a primeira metodologia proposta baseia-se num modelo matemático de simulação hidráulica e nas melhores práticas internacionais para gestão das perdas de água através da redução da pressão à entrada do sistema ou subsistema (mais comum na prática). Esta metodologia permite estimar os benefícios económicos directos originados pela redução da pressão na rede, particularmente em termos da redução da produção de água. No entanto, outros benefícios, como por exemplo, a redução da frequência de roturas, redução dos custos de controlo activo de fugas, a redução do consumo de energia e a redução do número de reclamações de utilizadores, podem ser adicionados. Além disso, pode ser ainda usada para definir o nível económico de perdas, ou seja, o nível a partir do qual não haverá mais interesse económico em reduzir as perdas de água. A segunda metodologia proposta neste trabalho está relacionada com o estudo de viabilidade e sustentabilidade do projecto de sectorização de redes de distribuição de água, incluindo a gestão da pressão ao longo da rede e durante o horizonte de projecto. Além disso, pode ser usada para planear os investimentos necessários em diferentes momentos, durante o horizonte de projecto, de acordo com as reais necessidades e os recursos financeiros da Entidade Gestora. Baseia-se na teoria dos grafos (algoritmo de Floyd-Warshall) para definir a geometria ou limites entre ZMC, e num algoritmo de optimização (baseado na meta heurística Simulated Annealing) ligado a um simulador hidráulico em regime quase-permanente para estudar as condições de fronteira entre ZMC, tal como o reforço da capacidade de transporte da rede e a gestão da pressão durante o horizonte de projecto. Para testar o desempenho das duas aplicações computacionais desenvolvidas, no final deste documento apresentam-se vários estudos de caso e discutem-se os resultados obtidos.

The occurrence of water losses in Water Distribution Systems is inevitable. Knowing that most of the real losses take place in distribution mains and in service connections, the methodology proposed in this paper is based on several leakage-assessment approaches from literature and on water distribution network modeling. This allows assessment of the benefits that can be achieved by pressure management in Water Distribution Systems, particularly in terms of water production reduction. Moreover, this approach can be useful for cost benefit analysis to help establish the level after which there is no more economic interest in reducing water losses (Economic Level of Leakage). Finally, the results from hypothetical case studies are presented and discussed, assuming the installation of Pressure Reducing Valves at District Metered Areas entry points.

ABSTRACT: Retrofit measures for buildings are in general evaluated considering the energy savings and life cycle cost. However, one of the main benefits, the increase of users comfort is very seldom analysed. In this work, two residential households representative of a large share of households in Portugal, were monitored and its thermal behavior was modeled using Energy Plus. The thermal evaluation of the pre-retrofit households shows that the winter season is problematic due to construction solutions and low availability for heating. The retrofit measures analysis was performed considering different retrofit solutions regarding envelope improvement and efficient systems implementation. In order to work around the question of comparing households that do not use energy for acclimatization and therefore have very low energy consumption, in the retrofit scenarios it was considered the thermal comfort evaluation value for the real case (pre-retrofit) and compared the energy consumption to achieve that same average comfort level (in this case avoiding high discomfort peaks). The measures that more rapidly pay the investment are those related with implementing active systems. The approach used in this paper, should be used in more calibrated models in order to have overall conclusions about the retrofit process at a larger scale.

ABSTRACT: Retrofit measures for buildings are in general evaluated considering the energy savings and life cycle cost. However, one of the main benefits, the increase of users comfort is very seldom analysed. In this work, two residential households representative of a large share of households in Portugal, were monitored and its thermal behavior was modeled using Energy Plus. The thermal evaluation of the pre-retrofit households shows that the winter season is problematic due to construction solutions and low availability for heating. The retrofit measures analysis was performed considering different retrofit solutions regarding envelope improvement and efficient systems implementation. In order to work around the question of comparing households that do not use energy for acclimatization and therefore have very low energy consumption, in the retrofit scenarios it was considered the thermal comfort evaluation value for the real case (pre-retrofit) and compared the energy consumption to achieve that same average comfort level (in this case avoiding high discomfort peaks). The measures that more rapidly pay the investment are those related with implementing active systems. The approach used in this paper, should be used in more calibrated models in order to have overall conclusions about the retrofit process at a larger scale.