107 research outputs found
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Assessing multi slot versus single slot pool-type fishways suitability for potamodromous cyprinids: An experimental approach using numerical modelling and fish
Developing new fishway designs that provide suitable hydrodynamic conditions for multiple native freshwater fish species is paramount to mitigate the negative effects of anthropogenic barriers in rivers. This poses an increased challenge in Mediterranean regions, where water availability is limited and issue of conflicting demands. Vertical slot fishways (VSF) are considered one of the best types of technical fishways for potamodromous fish species. However, they generally require a greater amount of water to operate relatively to other type of facilities. The present study used 3D numerical modelling to compare the hydrodynamics and assess the hydraulic suitability for multiple fish species, of a widely used VSF and of two multi slot fishway (MSF) configurations. The MSF configuration requires a lower discharge to operate (\u3e 20% less discharge) than the VSF, while keeping similar flow depths. With the reduction in discharge, the velocity, turbulent kinetic energy and Reynolds shear stress values for MSF are also much lower than the values for VSF (c. 20 – 40% less). Hence, besides requiring smaller discharges than similar VSF design, the MSF seems to be less selective for fish species, particularly smaller-sized individuals, and individuals with weaker swimming capacities. Passage performance of the Iberian barbel, Luciobarbus bocagei (Steindachner, 1864) was subsequently assessed when negotiating a VSF and a MSF in an indoor full scale experimental model. Results showed that the Iberian barbel performed a significantly higher number of movements in the MSF when compared to the VSF. On the other hand, no differences were found in the entrance time, entry efficiency and overall fish performance between configurations. This study shows that numerical modelling complemented with laboratory fish experiments can be an important tool to develop cost-effective fishways
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Session D7: Is CFD an Efficient Tool ao Develop Pool Type Fishways?
Abstract:
Rivers longitudinal connectivity is compromised by man-made obstacles, such as dams and weirs, which affect fish movements, leading to populations decrease and genetic deterioration. Properly designed fishways re-establish connectivity, allowing for fish migration. The aim of our work is to contribute to a more fast and efficient development of pool-type fishways using hydrodynamic modelling, based on fish behaviour experiments. Modelling free surface flows in hydraulic structures with complex geometry, like pooltype fishways, with aerated and complex flow patterns, represents a significant research challenge. Knowledge already acquired in an experimental full scale indoor pool-type fishway in previous studies is used. A 1:2.5 scaled fishway of this facility was built and used to characterize velocity and turbulence in a pool-type fishway with cross-walls equipped with bottom orifices. An offset orifice configuration was used with consecutive orifices positioned on opposite sides of the cross-walls, creating a sinusoidal flow path. The measurements of velocity fields were made using Particle Image Velocimetry (PIV) and Acoustic Doppler Velocimetry (ADV). Velocity maps were obtained at several positions, for planes parallel to the bottom and parallel to the sidewalls. Parameters that influence fishways efficiency like velocity fields, turbulent kinetic energy and Reynolds shear stresses were determined. A 3D computational fluid dynamics (CFD) model of the fishway was developed using a commercial software FLOW-3D. Velocity fields, turbulent kinetic energy and Reynolds shear stresses were compared with the ones determined from PIV measurements and ADV measurements and results deviations between experimental and numerical data were analyzed. The use of FLOW 3D to simulate mean velocity patterns and flow turbulence in pooltype fishways and its use as design tool for new fishway geometries are discussed
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Can vertical slot fishways (VSF) operate with less water without compromising effectiveness
Monitoring the Assessment of Vernacular Buildings using an ICT Method
Nowadays, one of the main challenges in high levels of education, is to deal with ICT as a tool in teaching methodologies. This article aims to present some results of the use of an ICT platform as a tool in spatial analysis. It is focused on the study of vernacular architecture buildings, based on the case study of wooden house villages of Tagus river banks, in Portugal. This is the unique legacy in this country, of wooden vernacular architecture in areas submitted to regular floods. The main typology of these buildings refers to stilt-houses, which have their roots in the middle XIX century. Along the time, they have been subjected to a degradation process caused by the lack of repair actions, driving to an aggravation of their status of conservation, or caused by repair actions, driving to an aggravation of their distance to the vernacular architectural matrix. Consequently, there are less than one hundred buildings remaining in five villages. The used ICT tool refers to the software DECMAvi, which is an evaluation method of buildings, designed on purposes to analyse two criteria of these territories of vernacular architecture; the status of buildings conservation and their level of proximity to the vernacular architectural matrix. This method was tested firstly in 2014 and then in 2016, and the results are allowing to obtain results coming from a comparative analysis during this period of time, in order to know if the buildings are better, worst or in same condition, and from a spatial analysis in between the considered villages and their vernacular buildings.info:eu-repo/semantics/publishedVersio
Odd and even partial waves of and in at 191 GeV/c
Exclusive production of ηπ− and η′π− has been studied with a 191 GeV/c π− beam impinging on a hydrogen target at COMPASS (CERN). Partial-wave analyses reveal different odd/even angular momentum ( L ) characteristics in the inspected invariant mass range up to 3 GeV/c2 . A striking similarity between the two systems is observed for the L=2,4,6 intensities (scaled by kinematical factors) and the relative phases. The known resonances a2(1320) and a4(2040) are in line with this similarity. In contrast, a strong enhancement of η′π− over ηπ− is found for the L=1,3,5 waves, which carry non- qq¯ quantum numbers. The L=1 intensity peaks at 1.7 GeV/c2 in η′π− and at 1.4 GeV/c2 in ηπ− , the corresponding phase motions with respect to L=2 are different.Peer Reviewe
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Passage Performance of two Cyprinids with Different Ecological Traits in a Fishway with Distinct Vertical Slot Configurations
The COMPASS Setup for Physics with Hadron Beams
The main characteristics of the COMPASS experimental setup for physics with hadron beams are described. This setup was designed to perform exclusive measurements of processes with several charged and/or neutral particles in the final state. Making use of a large part of the apparatus that was previously built for spin structure studies with a muon beam, it also features a new target system as well as new or upgraded detectors. The hadron setup is able to operate at the high incident hadron flux available at CERN. It is characterised by large angular and momentum coverages, large and nearly flat acceptances, and good two and three-particle mass resolutions. In 2008 and 2009 it was successfully used with positive and negative hadron beams and with liquid hydrogen and solid nuclear targets. This paper describes the new and upgraded detectors and auxiliary equipment, outlines the reconstruction procedures used, and summarises the general performance of the setup.Peer Reviewe
The Amazon Epiphyte Network: A First Glimpse Into Continental-Scale Patterns of Amazonian Vascular Epiphyte Assemblages
Epiphytes are still an understudied plant group in Amazonia. The aim of this study was to identify distributional patterns and conservation priorities for vascular epiphyte assemblages (VEA) across Amazonia. We compiled the largest Amazonian epiphyte plot database to date, through a multinational collaborative effort of 22 researchers and 32 field sites located across four Amazonian countries – the Amazonian Epiphyte Network (AEN). We addressed the following continental-scale questions by utilizing the AEN database comprising 96,448 epiphyte individuals, belonging to 518 vascular taxa, and growing on 10,907 tree individuals (phorophytes). Our objectives here are, first, to present a qualitative evaluation of the geographic distribution of the study sites and highlight regional lacunae as priorities for future quantitative inventories. Second, to present the floristic patterns for Amazonia-wide VEA and third, to combine multivariate analyses and rank abundance curves, controlled by major Amazonian habitat types, to determine how VEA vary geographically and ecologically based on major Amazonian habitat types. Three of the most striking patterns found are that: (1) VEA are spatially structured as floristic similarity decays with geographic distance; (2) a core group of 22 oligarchic taxa account for more than a half of all individuals; and (3) extensive floristic sampling gaps still exist, mainly across the highly threatened southern Amazonian deforestation belt. This work represents a first step toward unveiling distributional pattern of Amazonian VEA, which is important to guide future questions on ecology and species distribution ranges of VEA once the collaborative database grows allowing a clearer view of patterns
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Rarity of monodominance in hyperdiverse Amazonian forests.
Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors
EpIG‐DB: A database of vascular epiphyte assemblages in the Neotropics
Vascular epiphytes are a diverse and conspicuous component of biodiversity in tropical and subtropical forests. Yet, the patterns and drivers of epiphyte assemblages are poorly studied in comparison with soil‐rooted plants. Current knowledge about diversity patterns of epiphytes mainly stems from local studies or floristic inventories, but this information has not yet been integrated to allow a better understanding of large‐scale distribution patterns. EpIG‐DB, the first database on epiphyte assemblages at the continental scale, resulted from an exhaustive compilation of published and unpublished inventory data from the Neotropics. The current version of EpIG‐DB consists of 463,196 individual epiphytes from 3,005 species, which were collected from a total of 18,148 relevés (host trees and ‘understory’ plots). EpIG‐DB reports the occurrence of ‘true’ epiphytes, hemiepiphytes and nomadic vines, including information on their cover, abundance, frequency and biomass. Most records (97%) correspond to sampled host trees, 76% of them aggregated in forest plots. The data is stored in a TURBOVEG database using the most up‐to‐date checklist of vascular epiphytes. A total of 18 additional fields were created for the standardization of associated data commonly used in epiphyte ecology (e.g. by considering different sampling methods). EpIG‐DB currently covers six major biomes across the whole latitudinal range of epiphytes in the Neotropics but welcomes data globally. This novel database provides, for the first time, unique biodiversity data on epiphytes for the Neotropics and unified guidelines for future collection of epiphyte data. EpIG‐DB will allow exploration of new ways to study the community ecology and biogeography of vascular epiphytes
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