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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Enhancing Britain's rivers : an interdisciplinary analysis of selected issues arising from implementation of the Water Framework Directive

Hampson, Danyel Ian January 2016 (has links)
The Water Framework Directive requires reduced environmental impacts from human activities and for the assessment of the non-market benefits of pollution remediation schemes. This policy shift has exacerbated the research problems surrounding the physical, social and economic consequences of the relationship between land use and water quality. This research seeks to quantify the major socio-economic and environmental benefits for people which may arise as riverine pollution is reduced. To achieve these aims this research integrates primary data analyses combining choice experiment techniques with geographical information system based analyses of secondary data concerning the spatial distributions of riverine pollution. Current knowledge on the microbial quality of river water, measured by faecal indicator organism (FIO) concentrations and assessed at catchment scale, is inadequate. This research develops generic regression models to predict base- and high-flow faecal coliform (FC) and enterococci (EN) concentrations, using land cover and population (human and livestock) variables. The resulting models are then used both to predict FIO concentrations in unmonitored watercourses and to evaluate the likely impacts of different land use scenarios, enabling insights into the optimal locations and cost-effective mix of implementation strategies. Valuation experiments frequently conflate respondents’ preferences for different aspects of water quality. This analysis uses stated preference techniques to disaggregate the values of recreation and ecological attributes of water quality, thereby allowing decision makers to better understand the consequences of adopting alternative investment strategies which favour either ecological, recreational or a mix of benefits. The results reveal heterogeneous preferences across society; specifically, latent class analysis identifies three distinct groups, holding significantly different preferences for water quality. From a methodological perspective this research greatly enhances the ongoing synthesis of geographic and economic social sciences and addresses important policy questions which are of interest to a variety of stakeholders, including government departments and the water industry.
82

The analysis and application of artificial neural networks for early warning systems in hydrology and the environment

Duncan, Andrew Paul January 2014 (has links)
Artificial Neural Networks (ANNs) have been comprehensively researched, both from a computer scientific perspective and with regard to their use for predictive modelling in a wide variety of applications including hydrology and the environment. Yet their adoption for live, real-time systems remains on the whole sporadic and experimental. A plausible hypothesis is that this may be at least in part due to their treatment heretofore as “black boxes” that implicitly contain something that is unknown, or even unknowable. It is understandable that many of those responsible for delivering Early Warning Systems (EWS) might not wish to take the risk of implementing solutions perceived as containing unknown elements, despite the computational advantages that ANNs offer. This thesis therefore builds on existing efforts to open the box and develop tools and techniques that visualise, analyse and use ANN weights and biases especially from the viewpoint of neural pathways from inputs to outputs of feedforward networks. In so doing, it aims to demonstrate novel approaches to self-improving predictive model construction for both regression and classification problems. This includes Neural Pathway Strength Feature Selection (NPSFS), which uses ensembles of ANNs trained on differing subsets of data and analysis of the learnt weights to infer degrees of relevance of the input features and so build simplified models with reduced input feature sets. Case studies are carried out for prediction of flooding at multiple nodes in urban drainage networks located in three urban catchments in the UK, which demonstrate rapid, accurate prediction of flooding both for regression and classification. Predictive skill is shown to reduce beyond the time of concentration of each sewer node, when actual rainfall is used as input to the models. Further case studies model and predict statutory bacteria count exceedances for bathing water quality compliance at 5 beaches in Southwest England. An illustrative case study using a forest fires dataset from the UCI machine learning repository is also included. Results from these model ensembles generally exhibit improved performance, when compared with single ANN models. Also ensembles with reduced input feature sets, using NPSFS, demonstrate as good or improved performance when compared with the full feature set models. Conclusions are drawn about a new set of tools and techniques, including NPSFS and visualisation techniques for inspection of ANN weights, the adoption of which it is hoped may lead to improved confidence in the use of ANN for live real-time EWS applications.
83

Caracterização da qualidade das águas fluviais em meios peri-urbanos: o caso da bacia hidrográfica do Rio Morto - RJ. / Fluvial water quality characterization in peri-urban environments: the case study of Morto River catchment, RJ, Brazil.

Ivan Santos Mizutori 27 March 2009 (has links)
Esta dissertação apresenta os resultados do estudo de monitoramento da qualidade de água na região hidrográfica da Baixada de Jacarepaguá através de coletas e posterior análise laboratorial realizadas na bacia hidrográfica experimental e representativa do Rio Morto. A bacia possui características predominantes peri-urbanas. / This thesis presents the results of the monitoring study of water quality in the river basin district of Jacarepagua marshland through collections and further laboratory analysis conducted in experimental and representative basin of the Dead River. The basin has peri- urban predominant features .
84

Caracterização da qualidade das águas fluviais em meios peri-urbanos: o caso da bacia hidrográfica do Rio Morto - RJ. / Fluvial water quality characterization in peri-urban environments: the case study of Morto River catchment, RJ, Brazil.

Ivan Santos Mizutori 27 March 2009 (has links)
Esta dissertação apresenta os resultados do estudo de monitoramento da qualidade de água na região hidrográfica da Baixada de Jacarepaguá através de coletas e posterior análise laboratorial realizadas na bacia hidrográfica experimental e representativa do Rio Morto. A bacia possui características predominantes peri-urbanas. / This thesis presents the results of the monitoring study of water quality in the river basin district of Jacarepagua marshland through collections and further laboratory analysis conducted in experimental and representative basin of the Dead River. The basin has peri- urban predominant features .
85

Teplonosné látky otopných soustav / The heat transfer medium in heating systems

Michalíčková, Iveta January 2017 (has links)
Theme of diploma thesis is the heat transfer medium in heating systems. The thesis is departed to three parts. In the first part, there is a theoretical solution of heat transfer mediums. In the second part, there is a calculation solution of the project. Project solves heating of the apartment building. There are two variants of heating source and water treatment. Those variants are compared. The last part is experimental part. Theme of the experiment is quality of heating water in heating systems.

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