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Set-recovery of heat treated maritime pine wood prior and after compression
No full textPine (Pinus pinaster) wood samples were subjected to a combined densification and
heat treatment process. Samples were densified before and after heat treatment. The heat
treatment was carried out inside an oven at 190ºC for 2 to 6 h and wood densification
was performed in a hot press at around 48 bar pressure and at temperatures of between
160ºC and 200ºC for 30 min. Compression rate and density were determined after the
treatment. Set recovery was determined by thee cycles of water soaking followed by
oven drying. The best results were attained when densification was done before heat
treatment. The set recovery was less than 30% for the first two cycles and a little higher
in the third cycle. For wood treated for 6 hours, the set recovery was less than 15%.
Heat treatment before densification seems to be less effective than after densification to enable set-recovery.4pThe authors would like to express their gratitude to Instituto Politécnico de Viseu, the
Center for Studies in Education, Technologies and Health (CI&DETS) and the
Portuguese Foundation for Science and Technology (FCT).DE/NC
Estudo de soluções alternativas de dragagens para a estabilização da Lagoa de Óbidos
No full textNa lagoa de Óbidos, a forte interacção entre ondas e correntes de maré induz rápidas alterações
morfológicas na sua embocadura. Esta laguna possui um prisma de maré reduzido e uma dominância de
enchente em termos de níveis. Estes dois factores promovem um equilíbrio dinâmico instável na sua
embocadura que migra frequentemente para junto das margens e coloca em risco as construções
existentes (Oliveira et al., 2006). As soluções implementadas nos últimos anos correspondem
maioritariamente a dragagens com o objectivo de prevenir o fecho da embocadura. No entanto, estas
medidas com carácter provisório não foram capazes de impedir o fecho da embocadura da lagoa de
Óbidos em Janeiro de 2014. Este estudo visa contribuir para a gestão costeira da lagoa de Óbidos e tem
por objectivo avaliar dois planos de dragagens alternativos, comparando-os com o plano que foi
implementado na última década, através de um modelo morfodinâmico. A discussão de resultados será
efectuada através da análise dos prismas de maré, das diferenças de duração entre a vazante e a enchente e
dos volumes de sedimentos que atravessaram a embocadura durante um período de cinco meses após as
dragagens.45-46ppDHA/NE
On-line monitoring for improved wastewater system management: applications of UV-visible spectroscopy
No full textThe value of on-line UV/vis spectroscopy for wastewater quality monitoring in two different sewage management situations was confirmed. For decentralised wastewater treatment, spectral on-line monitoring of key quality parameters (COD, organic N) at the WWTP inlet was found to be possible, at two plants of different sizes and inflow characteristics. The produced data allowed the dynamic modelling of the treatment processes and the testing of control scenarios. In situ spectral monitoring in sewers was also successfully tested, with high potential in the management of drainage networks subjected to storm water inflows. In both situations, on-line UV/ vis spectrophotometry can thus become a key technology for real-time system management, leading to better use of infrastructures and resources and the achievement of environmental objectives more consistently and at lower costs.4 p27 (6)DHA/NESSpectroscopy Europ
Deteção de orifícios nas impermeabilizações de aterros de resíduos: método do Geosafe
No full textOs aterros de resíduos são obras concebidas para minimizar o efeito poluente dos resíduos no meio ambiente, mediante a utilização de sistemas basais de impermeabilização que incluem geomembranas, cujo desempenho é fundamental para garantir a eficácia de tais sistemas. O desempenho da geomembrana pode, porém, ser comprometido pela presença de orifícios, resultantes, sobretudo, de atividades construtivas inadequadas o que potencia a migração de contaminantes para o subsolo e para as águas subterrâneas, pelo que é indispensável proceder à deteção dos orifícios na geomembrana e à sua reparação, antes do início da exploração do aterro. Não existindo em Portugal um equipamento que permitisse a realização de ensaios expeditos e pouco onerosos para a deteção de orifícios em geomembranas, foi desenvolvido um equipamento designado por GeoSafe. Neste artigo apresenta-se o equipamento, bem como os resultados obtidos até ao momento.7pCD/C
Safety evaluation of concrete gravity dams sliding considering the variability of rock mass foundation hydraulic and mechanical properties
No full textIn many countries, including Portugal, the design of concrete dams is based on the use of a global safety factor. Adopting a probabilistic safety approach, the Eurocodes are based on the principles of the limit states design in conjunction with the partial safety factors method. Thus, to develop a compatible approach for the design of concrete dams, it is important to understand the contribution of the uncertainty of the hydraulic and mechanical rock mass properties to the safety of concrete gravity dams for the design loads, including high intensity seismic actions. In this work, a set of Portuguese gravity dams are assessed in a reliability framework, combining both design data and data collected in the service lifetime. Geometrical data, as well as the dead-weight action, the hydrostatic pressure and the maximum design earthquake were considered as deterministic variables. The coefficient of friction and the uplift , quantified by means of a factor under the drainage line, were considered as probabilistic variables. Using the Monte Carlo method, the frequency of violating the safety criteria under extreme seismic actions was evaluated for six dams. An annual probability of failure of 10-5 was obtained for a high intensity seismic occurrence, which is the value defined in t he national appendix of Eurocode 8 for a return period of 1000 years.11p.DBB/CHEFI
Framework for technical evaluation of decision support systems based on water smart metering: the iWIDGET case
No full textWater smart metering enables the measurement and reporting of water consumption at sub-daily intervals. However, assuming that increased availability of consumption information will necessarily result in changed behaviour is simplistic. The main scientific challenges for iWIDGET project are the management and extraction of useful information from vast amounts of high-resolution consumption data, the development of customized information to influence awareness and support behavioral change, and the integration of iWIDGET concepts into a set of decision-support tools for water utilities and consumers. In this paper, it is described the evaluation general framework, the iWIDGET system’s technical evaluation system and stakeholders involved.8 p119DHA/NESProcedia Engineerin
Assessment of stage–discharge predictors for compound open-channels
No full textThe accurate prediction of flood levels and velocities is a prerequisite to any appropriate management of
river valleys, where the mitigation of environmental, economic or human losses caused by flood events
is of paramount importance. During these events, rivers frequently acquire a compound channel
configuration.
Due to the 3D nature of compound channel flows, the stage–discharge curves are not as easily
predicted as in single channels. Despite the availability of 2D and 3D flow models that may solve this
question, 1D methods are often preferred due to the reduced data required and to the much shorter
processing time. In the last five decades, important research efforts have been devoted to the
improvement of 1D predictors of stage–discharge curves in compound channels. In this study, the
accuracy of seven of those methods is assessed by comparing their predictions with a large experimental
dataset, comprising symmetrical and asymmetrical compound channels with vertical and inclined main
channel sidewalls, and smooth and rough floodplains. To the authors’ best knowledge, this is the most
comprehensive assessment of stage–discharge predictors for straight compound channels since it
involves the highest number of predictors applied to the widest data set.
It was concluded that the methods that account for the momentum transfer between the main
channel and the floodplains display considerably better results than the traditional methods. For relative
depth (ratio between floodplain and main channel flow depths) higher than 0.25, predicted discharges
for the methods that account for the turbulent momentum exchange are within 5% of observed values.
Depending on whether the flow depth or the flow discharge is the pertinent variable, two different
methods seem to be the most appropriate to produce precise and safe predictions.62-67ppVolume 45DHA/NREFlow Measurement and Instrumentatio
Towards a dams safety management system for Angola
No full textDams have contributed to the human development and have brought many
benefits, such as delivering hydropower, irrigating agricultural fields, supplying
drinking water, or just for navigational and recreational purposes. Nevertheless, dams
are critical structures that raise multiple concerns and risks associated with the
ecological, social and economic impact. Angola has a rich and complex network of water
basins and dams that serves different strategic purposes as defined in its water resource
management policy and respective strategic plan that, namely, considers relevant to
build new dams and to better operate the existent ones. In fact, some of the most
important dams in Angola are equipped with safety management information devices that
perform data collection and storage for infrastructural analysis and reporting. However,
many of these systems are currently in a critical condition. The civil war of 1975-2002
took a toll on dam safety measures and systems and most of them are outdated or
malfunctioning. The dams that are presently under construction, like Matala, will
already be equipped with safety management devices that are able to perform
measurement of variables such as displacement and discharges, among others. Yet, new
and adequate legislation must be created for all these efforts to effectively take place: the
National Dam Safety Plan may provide the answer and framework to this state of affairs.
Additionally, in this paper we assert that a more complex and integrated system can help
to achieve this plan. Hence, the main contribution of this paper is the proposal of the
gestBarragens-2, a next-generation Dam Safety Management System (DSMS),
particularly fitting for the geographic and political context of Angola. This DSMS highlevel
architecture reflects our experience with the design, development and operation of
a former DSMS in Portugal over this last decade, but also the state of art analysis and
our own learning process, introspection and criticism. The gestBarragens-2
architectural view defines the complex integration of several subsystems in two
complementary dimensions: the applicational and the technological. The applicational
subsystems are mainly functional, while the technological subsystems provide crosscutting
features that are widely used in the DSMS as a whole.DBB/N
Assessment of soil characteristics for managed aquifer recharge using soil-column experiments
No full textManaged Aquifer Recharge (MAR) main purpose is to augment the water availability in aquifers during times of excess to help addressing water scarcity challenges. Besides, these systems can have the goal of improving the quality of the recharged water. One of the main existing challenges of MAR is to control the infiltration rates and avoid clogging due to physical, chemical and biological processes taking place during the transport of water through the
unsaturated and saturated zone. Soil-column experiments are frequently used to get information on the soil behaviour under controlled conditions.
In the framework of EU MARSOL project, several soil-column experiments were conducted at LNEC using a soil collected in SB Messines, one of the Algarve demo sites. This paper presents the first results concerning the soil flow
rate variations under different conditions, aiming at verifying the soil suitability for infiltration media in basins. The soil capacity for sorption and biodegradation of the pollutants from a wastewater treatment plant (WWTP) are also being tested, but the results are not yet available.05pDHA/NR
18th century Portuguese tiles: characterization and reproduction study of Ca-rich biscuits
No full textMajolica tiles from the 17th-18th centuries make up one of the most important art heritages of Portugal. Their characterization and gains in knowledge through their reproduction are important to obtain information about their production methods, raw materials used, origin attribution and to contribute to studies in conservation and development of treatments.
A group of Lisbon tiles from the late 17th to 18th centuries has been previously characterized and the biscuits now tentatively reproduced. Special attention was given to the effect of firing temperature and Ca compounds content on the final replica properties such as water absorption, porosity, water and thermal expansibilities, mechanical strength, chemical composition and mineralogy. Correlation models between the Ca compounds content and firing temperature were obtained for the previous properties. Replicas similar on those properties considered relevant were obtained that can be used in studies in conservation and in interventions.197-200pp.The authors acknowledge FCT for the financial support for the execution of this work (Project CerAzul: PTDC/CTM-CER/119085/2010).
LNEC supported with own funding the participation of João Manuel Mimoso and António Santos Silva, under Project 0202/111/19014 (IPERION-CH.pt)DM/NBPCProceedings of the International Conference Glazed Ceramics in Architectural Heritage (GlazeArch 2015