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Building vulnerabilities to fires at the wildland urban interface
No full textFires on the Wildland Urban Interface (WUI) have caused significant loss of life and colossal property and
natural environment damages in numerous countries around the world. The solutions to mitigate this fire
problem are complex, as it results from the fuel source changes from vegetation to structural materials in a fireprone environment and it involves the interaction of several factors that act synergistically to increase the
frequency of fires with severe potential destruction. In order to understand how and why buildings are damaged and destroyed under wildland fire attack, several surveys following historical large scale fire events, which resulted in significant building damages and/or losses, have been conducted worldwide. This paper aims to review and analyse the main characteristics of buildings and other structures that contributed to their vulnerability during fires at the WUI, based on the analysis of several post fire studies developed in Australia, United States of America and Mediterranean Europe (particularly Portugal, Spain, Greece). The different building traditions between the selected countries are discussed, as long as they affect building vulnerability to fires.12ppSeminário / VII International Conference on Forest Fire ResearchDE/NC
How to assess the effectiveness of energy management processes in water supply systems
No full textThe main objectives that generally motivate the implementation of energy management strategies, suggestions of possible assessment criteria and corresponding performance measures are presented in a systematic way. A methodology based on the hydraulic energy balance along water
pipe systems and four performance indices to assess energy efficiency is established. This
methodology is applied to a real-life water supply system for two consumption scenarios and two operating schemes. The calculation of index E4 and the comparison between scenarios and schemes rely on the hydraulic simulation of the system. The application of this methodology has demonstrated the robustness and practicality of the proposed new performance indices, being particularly relevant for the comparison of different measures for the improvement of energy efficiency, such as the use of variable speed pumps and the installation of micro-turbines. More applications are needed for
systems with different sizes, layouts and elevations in order to identify and to overcome practical application difficulties.558Volume 63 Number 5DHA/NESJournal of Water Supply: Research and Technology - AQU
Semi-Active Control of Base-isolated Structures Using a Nonlinear Feedback Strategy
No full textBase isolation systems have been proposed for reducing the transmission of seismic forces and energy to
buildings when subjected to earthquake loads. Passive devices are ofien prescribed to reduce displacements at the isolation levei but in certain circumstances structural interstorey drifis and absolute accelerations can increase. This work explores the use of semi-active devices whose input is obtained from an output nonlinear control law resulting from the transformation of the nonlinear system into a linear one which is then controlled bya proportional controller. Within this nonlinear feedback control strategy the whole system formulation is considered for deriving the control law. A two degree of freedom experimental model representative of a typical base isolated building, currently under development at LNEC, is used as an example to evaluate the ( performance of the proposed strategy when subjected to accelerograms for the Portuguese territory. The results of the experimental characterization of the model components and for a magneto-rheological damper are presented. Numerical simulation results show that the proposed strategy to command the damper in real time can reduce the base relative displacement with better performance at the superstructure leveI (interstorey and accelerations) than the damper working in the passive mode. Although a small incre ase in the base acceleration for one type of seismic action is observed when compared to the original structure, it is always lower than the one resulting with the passive case.8ppEURODYN - 2014 - IX International Conference opn Structural DynamicsCIC/NSE
Ensaio em mesa sísmica de um modelo de uma estrutura de contenção biancorada
No full textA resposta sísmica de cortinas bi-ancoradas suportando areia é avaliada com recurso a ensaios dinâmicos 1g em mesa sísmica. São apresentados e discutidos os aspetos relacionados com a execução do modelo físico, nomeadamente o faseamento construtivo e os equipamentos de observação utilizados. São apresentadas as condições de realização dos ensaios e discutidos os resultados obtidos.16pDE/NESD
Salinity modelling accuracy of a coastal lagoon: a comparative river flow analysis of basin model vs. traditional approaches
No full textThe main purpose of this study is to investigate the uncertainties in the modelling of salinity fields in the Ria de Aveiro lagoon associated with the estimation of river flow discharges. The prediction of fresh water inputs is necessary to properly implement forcing conditions and consequently to provide accurate forecasts of baroclinic circulation in coastal lagoons. Located in the north-western Portuguese coast, the Ria de Aveiro is a shallow vertically homogeneous mesotidal coastal lagoon with a complex geometry. Although it is tidally dominated, it receives freshwater from five rivers, the Vouga, Antuã, Cáster, Boco and Ribeira dos Moínhos, whose contributions are responsible for the salinity variation within the system. This research concerns the accurate prediction of river flow to be used in the operational forecast system of the lagoon. Given the lack of observed data for river discharges, as there are only two real time measuring stations located in the Vouga and Antuã river basins, but far from the lagoon, alternative estimation approaches are needed. In order to estimate the river discharges for all five rivers, two different approaches were considered: the first estimates the Vouga river flow, the major fresh water source, based on the nearest real time measuring station and estimates the other river flows based on river basin areas proportionality; the second establishes river flows based on the precipitation/river flow relationships for the Vouga and Antuã rivers and on the areas of the other river basins using the SWAT model. The methodology comprises the exploitation of the 3D unstructured-grid hydrodynamic model SELFE, required to adequately simulate the flow and transport of salt in very complex domains such as the Ria de Aveiro. The model is forced by water elevations at the ocean boundary and river flows at the river boundaries, and atmospheric drivers at the surface (wind stress, atmospheric pressure and heat fluxes). The salinity model predictions were compared with data from seven stations, and its accuracy was assessed through Root Mean Square Error (RMSE). The river flows estimated by the first method led to the best fit between observed and predicted salinity.f3t2pDHA/GT
Bons espaços e ambientes domésticos II
No full textReflectimos, assim, um pouco, sobre a importância do conforto ambiental falando nos aspectos da envolvente exterior, da espaciosidade, da funcionalidade, da acessibilidade e da segurança. Pensou-se, assim, um pouco, sobre a importância do conforto ambiental e da força imaginativa dos nossos mundos domésticos, numa dupla perspetiva que nos poderá garantir uma habitação agradável e imaginativa.3 fig8 pInfohabitar, Ano X, n.º 489DED/NUTRevista Infohabita
Linear and Sliding-Mode Control Design for Matrix Converter-Based Unified Power Flow Controllers
No full textThis paper presents the design and compares the performance of linear, decoupled and direct power controllers for three-phase matrix converters operating as Unified Power Flow Controllers (lIPFC). A simplified steady-state model of the matrix converter based UPFC (MC-UPFC) fitted with a modified Venturini high frequency PWI\I modulator is first used to design the linear controllers for the transmission line active (P) and reactive (Q) power. ln order to minimize the resulting cross-coupling between P and Q power control, decoupled linear controllers (DLC) are synthesized using inverse dynamics linearization. Direct power
controllers (DPC) are then developed using sliding mode control techniques, in order to guarantee both robustness and decoupled control. The designed P and Q power controllers are compared using simulations and experimental results. Linear controllers show acceptable steady-state behavior but still exhibit coupling
between P and Q powers in transient operation. DLC are free from cross-coupling but are parameter sensitive. Results obtained by DPC show decoupled power control with zero error tracking and guarantee faster responses with no overshoot and no steady-state error. Ali the designed controllers were implemented using the sarne digital signal processing (DSP) hardware.3357-3367ppVolume 29 / N.º 7CIC/NSEMRevista IEEE Transactions on Power Electronic
Cryptotermes brevis (Isoptera: Kalotermitidae) in the Azores: Lessons After 2 yr of Monitoring in the Archipelago
No full textThe dispersal flights of West Indian drywood termite, Cryptotermes brevis (Walker) (Isoptera: Kalotermitidae) were surveyed in the major cities of Azores. The sampling device used to estimate termite density consisted of a yellow adhesive trap (size 45 by 24 cm), placed with an artificial or natural light source in a dark attic environment. In addition, data from two other projects were used to improve the knowledge about the geographical distribution of the species. The level of infestation in the two main Azorean towns differed, with high levels in the houses of Angra do Heroı´smo, whereas in Ponta Delgada, there are fewer houses with high levels of infestation. The infestation in Ponta Delgada shows a pattern of spreading from the center outward to the city’s periphery, whereas in Angra do Heroı´smo, there was a pattern of spreading outward from several foci. The heavy infestation observed in Angra do Heroı´smo and the clear increase of infestation levels observed from 2010 to 2011 is a reason for concern and calls for an urgent application of an Integrated Pest Management (IPM) control strategy.7ppWe are indebted to all house owners for their availability to contribute to this study and Enésima Mendonça for Auto-Montage Syncroscopy Software termite images. This study was supported by grants M221-I 002-2009 TERMODISP (Direcção Regional da Ciência e Tecnologia (DRCT), Azores, Portugal), PTDC/CCI/72381/2006 África Annes (Fundação para a Ciência e Tecnologia (FCT), Portugal), and contracts with the Mayors of the main Azorean towns (Angra do Heroísmo, Ponta Delgada, Horta and Vila do Porto under the project Risk Communication Program—“United we stand divided we fall.” O.G., F.F., A.B., and N.B. were supported by grants from Azorean Government. M.T.F. was supported by the Ph.D. grant SFRH/BD/29840/2006 (FCT, Portugal). L.N. was supported by the FCT research project PTDC/ECM/099121/2008.vol 14DE/NCEJournal of Insect Scienc
Caracterização e modelação numérica da rugosidade de descontinuidades rochosas
No full textAs descontinuidades dos maciços rochosos influenciam o seu comportamento mecânico e
hidráulico e consequentemente as obras neles construídas. Este trabalho descreve o
desenvolvimento e aplicação de uma técnica de digitalização das superfícies de
descontinuidades rochosas que recorre a uma mesa digitalizadora, visando contribuir para a
compreensão dos mecanismos de contacto e desgaste. As superfícies numéricas obtidas são
analisadas usando parâmetros geo-estatísticos que podem ser comparados com outros semi-
empíricos, como o JRC, permitindo quantificar a evolução da rugosidade após ensaios
mecânicos de compressão ou deslizamento. Os resultados deste trabalho permitiram geração de
descontinuidades sintéticas que poderão ser usadas futuramente em modelos micromecânicos de
partículas para simular o comportamento mecânico e hidráulico de descontinuidades.10pDT/NIF20146 de Abri
Caracterização do comportamento dinâmico de edifícios através de análise modal experimental
No full textNeste artigo é apresentado o tipo de instrumentação, a metodologia utilizada e os resultados obtidos num ensaio de caracterização dinâmica realizado num edifício de betão armado de 9 pisos sem dimensionamento sismo-resistente construído no final da década de 1970 recorrendo à medição das vibrações causadas pela excitação ambiente. Apresenta-se também a metodologia de elaboração de um modelo numérico representativo com recurso a elementos finitos no qual se ajustaram alguns parâmetros para que as primeiras frequências de vibração e as respetivas configurações modais desse modelo correspondessem aos resultados experimentais. O principal objetivo deste estudo consiste no desenvolvimento de um modelo numérico mais refinado para o estudo do comportamento dinâmico da estrutura.16pDE/NESD