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- Calibration in Water Distribution Networks with Pressure-Driven AnalysisPublication . Muranho, João; Ferreira, Ana; Gomes, Abel; Sousa, J.; Marques, Alfeu SáWater distribution networks (WDN) connect consumers to the water sources, and its goal is to fulfil water demand. However, it is a well-known fact that WDN have losses and an important part of them occur at pipe level. Despite all the research efforts focused on this subject, the identification of leaky pipes is still a major challenge. EPANET is frequently used to simulate WDN’ models, using a link-node formulation, similar to a graph, where the water demands are assigned to the nodes. A linearized system of equations (mass and energy conservation laws) is iteratively solved by a Newton-Raphson algorithm. The EPANET is demand-driven, since it assumes the water pressure is always enough to satisfy the demands. However, on real WDN, states of insufficient pressure also occur. Besides that, the demand-driven approach is not suitable for pipe leakage simulation, which depends on the pressure. WaterNetGen — an EPANET extension— allows both demand and pressure driven simulations, including pipes’ leakage modelling. However, the leakage parameters (bursts and background leakage coefficients and exponents) must be set manually by an expert — manual calibration — for the whole network or for each pipe. This work proposes a calibration methodology to estimate the pipe background leakage parameters. The approach is tested on a set of synthetic models, generated by WaterNetGen, and then applied to a real WDN to assess its performance on real world conditions.
- SoTRAACE: Socio-technical risk-adaptable access control modelPublication . Moura, Pedro; Fazendeiro, Paulo; Marques, Pedro; Ferreira, AnaWithin the necessary security requirements, accesRisk Adaptable Accesss control measures are essential to provide adequate means to protect data from unauthorized accesses. However, current and traditional solutions are commonly based on predefined access policies and roles and are therefore inflexible by assuming uniform access control decisions through people’s different type of devices, environments and situational conditions, across enterprises, location and time. The most ubiquitous device that people now hold is the smartphone. We live in an age of the mobile paradigm of anytime/anywhere access from different types of connections and situations to different types of information. In this new age, access control models need to determine adaptable access decisions based on multiple factors aggregated at the moment of the request, to calculate the security risk and operational security needs, and not just to perform a predefined comparison of attributes. Thus, there is a need for more innovative, flexible, adaptive, dynamic, transparent and more resilient access control models, that are required for more heterogeneous requests. This paper presents a new dynamic access control model: SoTRAACE - Socio-Technical Risk-Adaptable Access Control Model. The model aggregates attributes from various domains to help performing a risk assessment at the moment of request. The risk assessment is balanced against the operational needs to provide the most accurate and secure access decision. As a proof of concept SoTRAACE is used to model and compare two different use-case scenarios in the healthcare sector.