5,008 research outputs found

    Ventilation heat transfer models in rooms

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    Identifying ecosystem key factors to support sustainable water management

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    There is a growing consensus that sustainable development requires a behavioral change, forced by firm decision-making. However, existing decision-supporting tools are unlikely to provide relevant information, hampered by the complexity of combined socio-economic and natural systems. Protecting the intrinsic value of ecosystems and providing sufficient natural resources for human use at the same time leads up to a wide span of management, ranging from species traits to governance. The aim of this study is to investigate the interactions between the natural and economic systems from the perspective of sustainable development. The way to reduce systems complexity by selecting key factors of ecosystem functioning for policy and management purposes is discussed. To achieve this, the Pentatope Model is used as a holistic framework, an ecosystem nodes network is developed to select key factors, and a combined natural and socio-economic valuation scheme is drawn. These key factors—abiotic resources and conditions, biodiversity, and biomass—are considered fundamental to the ecosystem properties habitat range and carrying capacity. Their characteristics are discussed in relation to sustainable water management. The conclusion is that sustainable development requires environmental decision-making that includes the intrinsic natural value, and should be supported by ecological modelling, additional environmental quality standards, and substance balances

    Turbulent mixed convection in an enclosure with different inlet and outlet configurations

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    Given the large impact of the building sector on the final energy demand, special interest lays in passive cooling techniques, such as night ventilation. Unfortunately, a lack of understanding concerning the coupling between the ventilation air and the thermal mass by night stands its widespread application in the way. Therefore, the authors of this paper investigate by computational fluid dynamics turbulent mixed convection cooling in a rectangular enclosure – resembling a night ventilated landscape office. Based on the 2D Annex 20 test case, four different orientations of the inlet and outlet are considered while varying the Archimedes number – ranging from forced to mixed convection. Also the location of thermally massive elements is varied. Locating the inlet and outlet at the top of the room induces the highest convective heat transfer. Meanwhile, locating the thermal mass at the floor has more potential than at the ceiling

    Reflexive pronouns in Spanish Universal Dependencies

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    In this paper, we argue that in current Universal Dependencies treebanks, the annotation of Spanish reflexives is an unsolved problem, which clearly affects the accuracy and consistency of current parsers. We evaluate different proposals for fine-tuning the various categories, and discuss remaining open issues. We believe that the solution for these issues could lie in a multi-layered way of annotating the characteristics, combining annotation of the dependency relation and of the so-called token features, rather than in expanding the number of categories on one layer. We apply this proposal to the v2.5 Spanish UD AnCora treebank and provide a categorized conversion table that can be run with a Python script

    Distribution and ecology of the stoneflies (Plecoptera) of Flanders (Belgium)

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    Based on a literature survey and the identification of all available collection material from Flanders, a checklist is presented, distribution maps are plotted and the relationship between the occurrence of the different species and water characteristics is analysed. Of the sixteen stonefly species that have been recorded, three are now extinct in Flanders (Isogenus nubecida, Taeniopteryx nebulosa and T. schoenemundi), while the remaining species are rare. The occurence of stoneflies is almost restricted to small brooks, while observations in larger watercourses are almost lacking. Although a few records may indicate that some larger watercourses have recently been recolonised, these observations consisted of single specimens and might be due to drift. Most stonefly population are strongly isolated and therefore extremely vulnerable. Small brooks in the Campine region (northeast Flanders), which are characterised by a lower pH and a lower conductivity, contained a different stonefly community than the small brooks in the rest of Flanders. Leuctra pseudosignifera, Nemoura marginata and Protonemura intricata are mainly found in small brooks in the loamy region, Amphinemura staandfussi, Isoperla grammatica, Leuctra fusca, L.hippopus, N. avicularis and P. meyeri mainly occur in small Campine brooks, while L. nigra, N. cinerea and Nemurella pictetii can be found in both types. Nemoura dubitans can typically be found in stagnant water fed with freatic water. Sustainable populations of these stonefly species can only be achieved when their present habitats are adequately protected and in addition, measures should be taken to connect and enlarge the remaining populations

    Municipal wastewater treatment with pond technology : historical review and future outlook

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    Facing an unprecedented population growth, it is difficult to overstress the assets for wastewater treatment of waste stabilization ponds (WSPs), i.e. high removal efficiency, simplicity, and low cost, which have been recognized by numerous scientists and operators. However, stricter discharge standards, changes in wastewater compounds, high emissions of greenhouse gases, and elevated land prices have led to their replacements in many places. This review aims at delivering a comprehensive overview of the historical development and current state of WSPs, and providing further insights to deal with their limitations in the future. The 21st century is witnessing changes in the way of approaching conventional problems in pond technology, in which WSPs should no longer be considered as a low treatment technology. Advanced models and technologies have been integrated for better design, control, and management. The roles of algae, which have been crucial as solar-powered aeration, will continue being a key solution. Yet, the separation of suspended algae to avoid deterioration of the effluent remains a major challenge in WSPs while in the case of high algal rate pond, further research is needed to maximize algal growth yield, select proper strains, and optimize harvesting methods to put algal biomass production in practice. Significant gaps need to be filled in understanding mechanisms of greenhouse gas emission, climate change mitigation, pond ecosystem services, and the fate and toxicity of emerging contaminants. From these insights, adaptation strategies are developed to deal with new opportunities and future challenges

    Opportunities and challenges for the sustainability of lakes and reservoirs in relation to the sustainable development goals (SDGs)

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    Emerging global threats, such as biological invasions, climate change, land use intensification, and water depletion, endanger the sustainable future of lakes and reservoirs. To deal with these threats, a multidimensional view on the protection and exploitation of lakes and reservoirs is needed. The holistic approach needs to contain not just the development of economy and society but also take into account the negative impacts of this growth on the environment, from that, the balance between the three dimensions can be sustained to reach a sustainable future. As such, this paper provides a comprehensive review on future opportunities and challenges for the sustainable development of lakes and reservoirs via a critical analysis on their contribution to individual and subsets of the Sustainable Development Goals (SDGs). Currently, lakes and reservoirs are key freshwater resources. They play crucial roles in human societies for drinking water provision, food production (via fisheries, aquaculture, and the irrigation of agricultural lands), recreation, energy provision (via hydropower dams), wastewater treatment, and flood and drought control. Because of the (mostly) recent intensive exploitations, many lakes and reservoirs are severely deteriorated. In recent years, physical (habitat) degradation has become very important while eutrophication remains the main issue for many lakes and ponds worldwide. Besides constant threats from anthropogenic activities, such as urbanization, industry, aquaculture, and watercourse alterations, climate change and emerging contaminants, such as microplastics and antimicrobial resistance, can generate a global problem for the sustainability of lakes and reservoirs. In relation to the SDGs, the actions for achieving the sustainability of lakes and reservoirs have positive links with the SDGs related to environmental dimensions (Goals 6, 13, 14, and 15) as they are mutually reinforcing each other. On the other hand, these actions have direct potential conflicts with the SDGs related to social and economic dimensions (Goals 1, 2, 3 and 8). From these interlinkages, we propose 22 indicators that can be used by decision makers for monitoring and assessing the sustainable development of lakes and reservoirs
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