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Kamalian, Ulric. "Integrated 2D-3D free surface hydro-environmental modelling." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/26089/.
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An integrated horizontally two- and fully three-dimensional numerical model system has been developed based on a combined unstructured and σ-coordinate grid to simulate the flow and water quality process in large water bodies with a focus on the three dimensional behaviours at specific areas. The model is based on the time dependent Reynolds-Averaged Navier-Stokes equations with a non-hydrostatic pressure distribution and a baroclinic force being incorporated in the three dimensional (3D) model. The two sub models interact dynamically during the solution procedure with no time-step restriction due to integration. The main idea is to use a fractional step algorithm for each model and then integrate the two models fraction by fraction. Hybrid 2D-3D finite volume cells have been introduced for the link nodes which are partly in the 2D domain and partly in the 3D domain. Thus an interpolation/averaging procedure at the interface and domain overlapping is no longer needed. The 3D model uses the projection method for pressure calculation. The advection equation is solved by the semi-Lagrangian method. Other components are solved via the finite element - finite volume (FV) method. The water surface is determined implicitly through a global matrix equation created by assembling the domain's matrices. The cell integrals are calculated analytically to eliminate a common source of numerical diffusion due to the use of approximation techniques for the FV integrals. The horizontal gradients of the density and shear stresses are calculated on true horizontal planes, in order to avoid artificial velocity and diffusion in highly stratified flows. Neumann interpolation elements with virtual nodes have been introduced at Neumann type of boundaries for more accuracy. The integrated model has been verified using analytical solutions and benchmark test cases, including the Ekman velocity distribution, wind driven circulation, lock exchange and integrated 2D-3D flows in basin. The results show the model is capable of the model for accurate simulation and implicit 2D-3D integration. Keywords: integrated modelling, hydrodynamic numerical model, non-hydrostatic, unstructured mesh, hybrid finite element finite volume method.
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Giles, David. "Computer-based modelling and analysis in engineering geology." Thesis, University of Portsmouth, 2014. https://researchportal.port.ac.uk/portal/en/theses/computerbased-modelling-and-analysis-in-engineering-geology(091c5104-4dbb-4e90-b897-aaf34702100a).html.
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This body of work presents the research and publications undertaken under a general theme of computer-based modelling and analysis in engineering geology. Papers are presented on geotechnical data management, data interchange, Geographical Information Systems, surface modelling, geostatistical methods, risk-based modelling, knowledge-based systems, remote sensing in engineering geology and on the integration of computer applications into applied geoscience teaching. The work highlights my own personal contributions and publications under this theme as well as collaborations and output emanating from PhD co-supervisions which have included the following projects: A geotechnical and geochemical characterisation of dry oil lake contaminated soil in Kuwait; Dust dispersion monitoring and modelling; Geotechnical properties of chalk putties; The application of airborne multispectral remote sensing and digital terrain modelling to the detection and delineation of landslides on clay dominated slopes of the Cotswolds Escarpment; Domestic property insurance risks associated with brickearth deposits; Development of a knowledge-based system methodology for designing solid waste disposal sites in arid and semi-arid environments; GIS Techniques as an aid to the assessment of earthquake triggered landslide hazards; The application of GIS as a data integrator of pre-ground investigation desk studies for terrain evaluation and investigation planning; The influence of clay mineralogy pore water composition and pre-consolidation pressure on the magnitude of ground surface heave due to rises in groundwater level. My publication record comprises; Pathfinder and seminal papers; Papers from co-supervised PhD programmes; Pedagogic contributions; Encyclopaedia entries; International collaborations; Technical authorship and support; Other published contributions; Confidential development and technical reports and Internal briefing papers.
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Lovas, Stéphanie. "Theoretical modelling of two wave-power devices." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/57988.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, February 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 161-163).
Many wave energy devices are currently studied. In this thesis we focus on two specific devices: the Oscillating Water Column (OWC), and the buoys. In the first part of this thesis we examine the effects of coastline geometry on the performance of an OWC. Under the assumption of inviscid irrotationnal flow, we develop a linear theory for the velocity potential for the case of a coastline of arbitrary apex angle. Scattering and radiation problems are solved separately using eigenfunctions expansions, and are then combined to study the energy extraction rate. Numerical simulations for a convex and a concave corner are considered and comparison with an OWC at the tip of a thin breakwater and on a straight coast are discussed. Assuming that the multiple-turbine system can be controlled over a wide range of frequencies, we study the effects of fixed chamber size and air compressibility on the optimal power extraction. A simpler way of optimization is then develop and we show that this simpler scheme can achieve almost as high an efficiency as the idealized many-frequency optimization. In the second part of this thesis, we first model theoretically an array of cylinders and then apply the theory developped to an array of buoys. However, numerical difficulties encountered for the array of cylinders have led to the conclusion that the theory developed is numerically inefficient, although it is accurate.
by Stéphanie Lovas.
S.M.
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Taiwo, Adewale Matthew. "Receptor modelling of industrial air pollutants." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4662/.
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The presence of particulate and gaseous pollutants at elevated concentrations in the atmospheric environment is detrimental to public health. The present study has investigated the impacts of a steelworks complex on the air quality in Port Talbot, South Wales, United Kingdom. Different offline and online air monitoring instruments were deployed to four sites around the perimeter of the steelworks (at one coastal site (Little Warren LW) and 3 inland sites placed along the length of the steelworks (Fire Station FS, Prince Street PS and Dyffryn School DS) in the study area for a four-week campaign (April 16 to May 16, 2012). Prior to Port Talbot campaign, a separate two week sampling (March 30 to April 12, 2012) was conducted at Elms Road Observatory Site (EROS) for a representation of an urban background. Gaseous and meteorological data logged during the period of sampling were also collected from the Automatic Urban and Rural Network (AURN) site at Port Talbot Margam (FS site). Hourly and daily data collected were prepared for receptor modelling using Positive Matrix Factorization (PMF) and with the use of Open Air and Lakes Environmental WRPLOT View software, windrose and polar plots were produced to show the directional emissions of particulate and gaseous pollutants. The online sampling instrument of Aerosol Time of Flight Mass Spectrometer (ATOFMS) as well as PMF solutions for Streaker and Partisol were able to identify different processing units of the steelworks responsible for pollutant emissions. The polar plots for most air pollutants revealed the steel industry as the major contributor to air pollution in the study area.
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Khalid, M. (Muhammad). "Erosion of organic sediments and modelling of sediment transport in peat drainage area." Master's thesis, University of Oulu, 2015. http://urn.fi/URN:NBN:fi:oulu-201502131085.
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Detailed knowledge from physical properties of sediment such as erosion and settling velocity are crucial for modelling as well as for water protection planning and management. The main purpose of this research was to determine the critical shear stress (τcr) and settling velocity of the organic sediments in different peatland drainage areas and headwaters in Finland. Further, KINEROS2 erosion model was applied to peatland forestry and peat extraction conditions to simulate runoff hydrograph and suspended solid yield from two experimental catchments. To determine mean τcr and settling velocity totally 119 undisturbed sediment samples were taken from the natural streams, ditches and brooks across Finland. The samples covered main peatland uses, peatland forestry and peat extraction sites. Furthermore, to determine the effect of peat soil properties on sediment erosion and settling, peat soil samples were collected from 9 peat extraction areas. These samples were used to prepare sediments in laboratory setting. Cohesive strength meter (CSM) was applied to measure the τcr and settling velocity in laboratory and in-situ conditions. Results were compared against physical properties of sediment or peat soils and further compared against different peatland uses.
The critical shear stress over all samples ranged from 0.0057 to 0.428 N m⁻² (mean value 0.116 ± 0.07 N m⁻²). τcr in peatland forestry ditches ranged from 0.0057 to 0.428 N m⁻² (mean value 0.07 ± 0.1 N m⁻²), and in peat extraction sites from 0.006 to 0.421 N m⁻² (mean value 0.12 ± 0.06 N m⁻²). Similarly, τcr of artificially prepared samples from peat extraction area ranged from 0.012 to 0.112 N m⁻² (mean value of 0.059 ± 0.028 N m⁻²). At Koivupuro peatland forestry site, measurements were done in laboratory as well as in-situ. Results gave slightly different values; in-situ τcr ranged from 0.005 to 0.305 N m⁻² with the mean value of 0.03 ± 0.075 N m⁻², and the laboratory results ranged from 0.008 to 0.310 N m⁻² with the mean value of 0.125 ± 0.06 N m⁻². Degree of humification (DOH) and dry bulk density were found to be positively related to critical shear stress.
The settling velocity results for Koivupuro catchment ranged from 0.0004 to 0.131 m h⁻¹ (mean value 0.016 ± 0.034 m h⁻¹) and 0.0004 to 0.456 m h⁻¹ (mean value 0.144 ± 0.134 m h⁻¹) for other organic peat samples. Degree of humification (DOH) and settling velocity showed no correlation while dry density of settled sediment was found inversely proportional to settling velocity. This study showed that CSM can be used to determine τcr and settling velocity from organic sediment samples. Results can be applied in modelling purposes, and in dimensioning of water protection methods such as settling basins.
Eleven rainfall-runoff events from two different catchments were selected for the study to simulate runoff hydrographs and associated sediment yields in different conditions. When properly calibrated for each event, KINEROS2 model produced sufficient estimations of runoff hydrographs for peatland forestry and peat extraction sites but failed to produce reliable estimations of suspended sediment yields. Moreover, unrealistic parameter values sometimes had to be used in model calibration due to model inability to simulate groundwater or soil water response in ditch flow. Thus the model could not be validated for varying initial conditions and rainfall events.
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Kaneko, Yoshio. "Modelling of shear-off failure of concrete : fracture mechanics approach." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13200.
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Reyes, Olivia Maria Lei. "Experimental study and analytical modelling of compressive fracture in brittle materials." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13869.
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Dar, Maital. "Modelling the performance of revenue management systems in different competitive environments." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35119.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.Includes bibliographical references (p. 124-129).
In the wake of contemporary widespread fare simplification in many major airline markets, this thesis is concerned with the possibilities and the potential for airline revenue management in less-differentiated fare environments. Traditional revenue management has relied upon the assumption that independent demands exist for different fare class products, and can be forecast as such. However, in less-differentiated fare environments this assumption has been shown to lead to "spiral-down" in revenues. Hence, in this thesis, seat inventory control methods are simulated in less-differentiated fare environments and their relative performances are compared. The methods tested are: EMSRb-based Fare Class Yield Management (FCYM); Heuristic Bid Price (HBP); Displacement Adjusted Virtual Nesting (DAVN); and Probabilistic Bid Price (ProBP). Each of the methods is tested in conjunction with two different demand forecasting philosophies: the traditional pickup (or moving average) forecaster which is based on the assumption of independent demands; and a hybrid forecasting method based on the notion that there is one demand for flexible products and another demand for the cheapest product. The methods are simulated in two different competitive airline network environments: a symmetric network with simplified fares; and a more complex non-symmetric network with mixed fare structures. Simulation shows that the performance of all four revenue management methods suffers in less-differentiated fare environments if they continue to use traditional forecasting. Methods that forecast demand at the path level see inflated forecasts for more expensive products, leading them to reject too much lower-class demand; methods that forecast demand at the leg level see diminished forecasts for the more expensive products, leading them to accept too much lower-class demand. The efficacy of FCYM improves in less-differentiated fare environments, providing a gain of about 19% over "First Come First Served" revenues (as compared to the 6% gains seen previously), nevertheless, fare product simplification still results in overall network revenue losses of around 16%. Incremental gains from O-D control when using traditional forecasting range from 0.44% to 1.93%.o over FCYM. In contrast, when the new hybrid forecaster is used, revenue management performance improves significantly, and all methods provide larger revenue gains in all competitive network environments. Revenues under FCYM are now 1.7-2.6% higher than when traditional forecasting is used. When using hybrid forecasting, the incremental gains from O-D control now range from 2.6% to 4% over FCYM.
by Maital Dar.
S.M.
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Bruchmuller, Jorn. "Modelling the degradation of particles in fluidised beds." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/333308/.
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This thesis focuses on modelling the degradation of particles in gas-solid fluidised beds. Modelling is performed by using a coupled approach where the gas phase is treated as a continuum and the solid phase is represented by individual discrete particles, using the discrete element method (DEM). This approach makes it possible to access individual particle properties. By implementing new modelling techniques into the DEM framework, the individual particle degradation behaviour can be numerically described with high accuracy. The main interest is to understand more complex gas-solid systems as encountered e.g. in fluidised beds which might contain numerous degrading particles. This work focuses on verifying and validating these sub-models to be able to obtain accurate information for further suggestions in operation and optimisation of dense particulate systems. Particle degradation is studied by means of thermophysical, thermochemical and mechanical aspects. Drying (thermophysical) is an energy intensive process which makes further research inevitable for further optimisation. Large particles during drying develop temperature and species gradients along their radius, affecting the product quality. The DEM has been used to monitor flow, particle and subparticle properties which have been found useful to control, operate and optimise such large particle drying processes. Pyrolytic (thermochemical) conversion of biomass in fluidised beds represents a promising route for the production of biooil. This process has been modelled and studied under consideration of drying, shrinkage, segregation and entrainment. Breakage or mechanical degradation is often encountered in engineering applications and requires a much better process understanding. Therefore, a new discrete fragmentation method (DFM) has been developed to study breakage in dense particle systems such as fluidised beds but also mills or crushers. Much reliable breakage information can be obtained to further optimise such systems.
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Angeles, Justin Victor V. (Justin Victor Velayo). "Water quality modelling for recreational use in the Kallang River Basin, Singapore." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90006.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 42-45).
Singapore's Active, Beautiful, and Clean Waters Programme (ABC) aims to provide functional use of its water bodies to the public. The Kallang River Basin, being part of the ABC Programme, will be used for recreational purposes such as dragon boating and other water sports. In order to provide safe recreational use for the public, the water quality of the Kallang River Basin needed to be determined and modeled. The water quality indicator chosen to be analyzed was Escherichia coli (E. coli) bacteria. A heuristic study was performed in order to determine the water quality and as well determine if water quality modeling was feasible for the Kallang River Basin. The study employed the United States Environmental Protection Agency WASP (Water Quality Analysis Simulation Program) model. Through WASP model simulations, it was found that certain parts of the Kallang River Basin were not suitable for recreational purposes and others parts were deemed suitable. E. coli concentrations predicted by the model were within the range of actual field data but diurnal variations were not captured by the model for lack of data with which to specify diurnally varying inputs. The WASP model created by this study suggests that water quality modeling for the Kallang River Basin is feasible but there are modifications that need to be made to accurately capture diurnal variations experienced by the Kallang River Basin. Future investigation into the diurnal variations would contribute to creating a more complete and accurate model for the Kallang River Basin.
by Justin Victor V. Angeles.
M. Eng.
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Poudel, Sabin. "Modelling of a Generic Aircraft Environmental Control System in Modelica." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-156675.
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This thesis documents the modelling of generic Environmental Control System(ECS) of an aircraft in Modelica by utilizing components from free version of theTTECCS (Technical Thermodynamic Environmental Control and Cooling Systems) library. In doing so, components used for developing ECS from the TTECCS library are mathematically verified with theoretical formula in MATLAB. Selected components are investigated with valid input data to initialize the simulation and verify its behaviors with corresponding available data. Hereinafter, the object-oriented modelling method is used to integrate ECS components to develop a functional system. The main function of ECS is to regulate the pressure and temperature inside the cabin to accepted physiology flight safetylevels. Different types of ECS architecture are presented in this document. An ECS developed here is based on the bootstrap system and consists only one cooling unit comprised with the source, pipes, two heat exchanger, compressor, turbine, temper-ature control valve, pressure control valve, and sinks. Dry air(Ideal gas) is used as a medium in the system. Temperature drop along each component corresponds to available A320 cruise flight data in order to calculate the top level parameter and to initialize the components, subsequently an ECS system. Several systematized methods for Object-oriented modelling and system design were studied and steps are extracted accordingly that suits to initiate the procedurefor this project, which is also presented. Time domain simulation is performed inModelica and Dymola. A simplified control system is built to regulate the system, therefore restrained it as a future work to develop real in-flight condition control system of an ECS.Top level parameters were selected within valid customized ranges for developing a performance map of the components. After generating the map, optimal data from the map were taken to initialize final ECS. The simulation results of the final model is then compared to A320 flight data which is comparable in behavior; this was expected. Above all, simulation environment Modelica and free version of TTECCS library components are reliable to develop ECS in order to investigate ECS components behavior and predict cabin conditions before developing a prototype.
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Clarke, Peter. "Mathematical modelling of BIPV-micro wind system : production, storage and usages." Thesis, Edinburgh Napier University, 2009. http://researchrepository.napier.ac.uk/Output/3745.
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This thesis deals with the following aspects of renewable energy technology; solar energy modelling within the urban environment, performance of building integrated renewables including solar photovoltaics and micro wind technology. The development of hydrogen technology and electric zero emission transport is also reviewed. Incident solar irradiation models have been developed to accurately incorporate the effects of shading, in order to enable the detailed simulation and estimation of solar energy systems within the urban environment. Both the Integrated Slope Radiation Model (ISRM) and the Sky Radiance Distribution Model (SRDM) have been developed to use readily available horizontal sub-hourly or hourly solar global and diffuse irradiation data. Shading parameters caused by the surroundings, such as building and trees, can be incorporated into the models. A software package based on these models has been developed to allow the design and simulation of solar energy systems. Horizontal solar global irradiation data is readily available around the world. However, diffuse irradiation data is available to a lesser extent. To resolve this problem and enable the above mentioned incident solar irradiation models to be used throughout the world a simple regression set was developed between the diffuse ratio, k, and clearness index, kt, to enable the estimation of horizontal diffuse irradiation from its horizontal global counterpart. A review of building integrated renewable technology has been carried out. This includes the review of the performance of Edinburgh Napier University photovoltaic facade which has been in operation for over three years. Building mounted micro turbine technology is also reviewed. Performance analysis of three micro wind turbines installed on the rooftop of Edinburgh Napier University was undertaken, along with an analysis of the available wind regime observed at roof level. A software package was developed to aid the monitoring and analysis of both micro wind turbines and their observed wind regime. Hydrogen technology is reviewed as part of the development of Napier Hydrogen Research Facility, enabling the demonstration of hydrogen generation, storage and use from renewables. Finally, an analysis and comparison of a zero emission electric scooter with a conventional petrol car for use as urban transport was carried out. A driving cycle analysis was also undertaken to determine the environmental impact of both vehicles.
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Klosek, Justin T. (Justin Thayer). "The integration of fluid dynamics with a discrete-element modelling system : algorithms, implementation, and applications." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10738.
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Romps, John F. (John Francis). "Modelling track maintenance and its effects on the reliability of a single track railroad line." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12397.
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Seidahmed, Osama M. E. (Osama Mohamed Elmekki). "Observations and mechanistic modelling of the role of Aedes mosquitoes in dengue transmission in Singapore." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113492.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 182-209).
Dengue is the most prevalent human arboviral disease in the world with an estimate of 390 million cases per year. The disease is mainly transmitted by two mosquitoes: Aedes aegypti and Ae. albopictus. Despite the continuous efforts to curb the spread of the disease in Singapore, there is an upsurge in dengue epidemics. In this thesis, the role of Aedes mosquitoes in shaping the spatiotemporal patterns of dengue transmission in Singapore is investigated. Field surveys are carried out to study the effect of monsoons on the disease vectors; the impact of urban housing on spatial patterns of dengue transmission is explored; and mechanistic models are developed to simulate the seasonality of dengue occurrence in the city. The role of monsoons in shaping the seasonal pattern of dengue is investigated. Singapore has no pronounced dry season, while dengue cases decrease every year after a very wet monsoon. A preliminary survey documents that Aedes mosquitoes breed in drains close to houses. A hypothesis that the very wet monsoon results in a strong reduction of outdoor breeding of Aedes is tested using field data. A one-year entomological survey confirms the hypothesis and shows that a monsoonal sequence of flushing-drying conditions in the drains shapes the seasonal abundance of Aedes in Singapore. This finding can be used to optimize vector control efforts and to better understand dengue transmission in the context of climate change. The influence of urban housing on the distribution of dengue at neighborhood and country scales is studied. Dengue incidence, vector abundance, and drainage network density are found to be higher in a subarea of low-rise housing in Geylang. Further, a holistic analysis at the country-scale confirms the role of urban housing in shaping spatial patterns of dengue. Dengue incidence is found to be proportional to the fraction of the area (or population) of low-rise housing. This finding suggests that affording public housing in agglomerations of high-rise buildings would have a positive impact on dengue control if this urban housing develops at the expense of low-rise areas. A mechanistic model is developed to investigate the role of drainage networks in the outdoor breeding of Aedes and transmission of dengue virus. The HYDRology, Entomology and DEngue Transmission Simulator (HYDREDETS) consists of three coupled dynamic models, with an explicit representation of the spatial domain. The model is calibrated using field observations to study rainfall-effects on flushing/drying of aquatic stages and re-inoculation by dormant eggs. Dengue vertical transmission and the role of human movements are incorporated in the model. HYDREDETS is capable of simulating patterns of dengue transmission in Singapore, however with reduced seasonality. This finding supports the hypothesis that dengue seasonality in Singapore can be attributed to a significant degree, to flushing-drying sequence in outdoor breeding habitats. Based on the conclusions of this thesis, spatiotemporal patterns of dengue in Singapore are shaped by climate and urban ecology which influence the ecology of Ae. aegypti and Ae. albopictus. HYDREDETS is a new modeling tool tailored to the study of vector-borne diseases related to urban hydrology. Dengue vector control can be optimized using these new tools and the improved understanding of the disease ecology.
by Osama M. E. Seidahmed.
Ph. D.
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Mahapatra, Indrani. "Modelling environmental risks and conceptualising 'responsible innovation' for nanotechnology enabled medical applications." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/7102/.
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Medical products based on nanomaterials can revolutionise disease diagnosis and management modalities via faster, non-invasive diagnostic techniques and targeted therapeutic delivery and will be used extensively in coming years. The central goal of this thesis was to understand environmental risks that could potentially arise from mass production and wider use of nanotechnology enabled medical products and to gather insights from experts’ perceptions on “Responsible Innovation”. The research presented here uses a mixed methods approach to answer the research questions. By applying probabilistic mass flow modelling concept, prospective environmental concentrations of nanomedicine was estimated and a preliminary environmental risk assessment was done using gold nanoparticles in medical applications (potential of commercialisation and marketed) as a case study. This demonstrated that environmental risks from gold nanoparticles for the two major compartments (sludge applied soil and water) is likely to be minimal in the near future. The second component of the research involved 38 interviews with academics and 28 interviews with representatives from regulatory bodies, industry and funding bodies to understand their perceptions on environmental hazards and risks from nanomedicine and their views on the meaning of the concept of “Responsible Innovation”. This revealed that risks from nanomedicine can be compared with risks from existing chemicals and that “Responsible Innovation” is a phrase which can be discussed based on an individual’s experience and discipline.
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Joseph, Genora M. D. "Improved dust dispersion modelling for surface quarries : an optimized RANS k − ε approach." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33767/.
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Conventional dust dispersion models which employ Gaussian concentration distributions are routinely applied to predict the dispersion and deposition of fugitive dust arising from quarrying activity. However, these models are known to over-predict the long range transport of particulates beyond the confines of the quarry pit, because their complex terrain algorithms are unable to accommodate the steep gradients which are typically encountered in quarry excavations. They therefore cannot account for the internal flow regimes which contribute to the removal of suspended particulates from the air stream. Consequently, a need arises within the extractive industries, for improved dust dispersion models that are not constrained by quarry topography. This research project attempts to address this deficiency in the modelling of dust emissions from quarry blast events, by presenting an optimized RANS k−ε approach which can adequately simulate the flow-field in which particulates are entrained under a range of meteorological conditions. The stages involved in the incremental development of the numerical model are documented in the thesis, and commence with characterization of the atmospheric boundary layer. In particular, the Monin-Obukhuv Similarity Theory is applied to parametrize the atmospheric surface layer, which exerts the most influence on the dispersion and deposition of near-ground particulate emissions. Modifications to the standard k − ε model coefficients and the inclusion of buoyancy source terms have been adopted in this work, in accordance with previous studies by Alinot and Masson (2005). These modifications ensure that the turbulence closure equations are compatible with Monin-Obukhuv Similarity scaling of the atmospheric surface layer. The Businger-Dyer flux profile functions have been employed to introduce stability modifications to the logarithmic velocity, temperature and turbulence profiles which have been defined at the inlet boundaries of the computational domain to enable numerical representation of both adiabatic and diabatic atmospheric conditions. Furthermore, the Lagrangian Discrete Phase Model has been coupled with Eulerian solution of the flow field to provide a robust means of replicating fugitive dust dispersion through the stochastic tracking of injected particulates. The project also presents a consolidated post-processing methodology to incorporate wind direction variability due to mesoscale atmospheric effects into the CFD model. This methodology use the Moore (1976) equation to parametrize the standard deviation of wind direction variability and proposes a novel, Gaussian probability weighted averaging procedure to arrive at a resultant plume which accounts for the influence of mesoscale wind variability on particulate trajectory and improves the k −ε predictions of lateral spreading of the dust plume. Simulations of flow and dispersion over a series of idealized cosine depressions of varying aspect ratio have been used to assess model predictions of the flow regime and the corresponding plume attenuation within artificial valleys. To allow the model to accommodate negative terrain elevations and to produce profiles of the flow variables which conform to wall topography, a wall-distance scalar has been introduced to ensure consistency of the inlet profile with the flow solution within the domain. These simulations have demonstrated that the proposed model surpasses UK-ADMS in terms of its ability to resolve strong recirculation regimes in deep depressions. The project culminates in a case study of the Old Moor Quarry in Buxton, Derbyshire. This case study tests the viability of the proposed k−ε model and validates the model predictions of dust dispersion with field measurements obtained over the course of a monitoring campaign of approximately one month duration. Meteorological pre-processing steps in accordance with the findings of Holtslag and Van Ulden (1983) have been employed to derive atmospheric surface layer input parameters from routine meteorological data measured at the quarry site, eliminating the need for sophisticated meteorological measurements. Dust dispersion predictions obtained using the conventional dust dispersion model UK-ADMS, have been compared to the CFD model results to demonstrate the improved prediction accuracy of the proposed k −ε approach. Notably, the CFD model is shown to account for the various flow regimes which arise due to the combined effects of the site meteorology and the complex terrain of the quarry excavation. Importantly, the statistical Performance metrics, FAC2, MG, FB and NMSE recommended by Hanna et al. (2004) for the evaluation of dispersion model performance, have been used to assess the accuracy of fugitive dust deposition predictions obtained from the proposed model. The performance evaluation exercise indicates that the buoyancy modified k − ε model outperforms UK-ADMS for all of the metric tests. The incorporation of the wind variability weighted averaging procedure in the case study simulations is seen to reduce uncertainty due to random error, quantified by NMSE. This due to the fact that the wind variability averaging procedure evens out outlying predictions which may be due to the inherent stochasticity of the DPM model.
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Gontier, Mikael. "Spatial prediction tools for biodiversity in environmental assessment." Doctoral thesis, Stockholm : Land and Water Resource Engineering (Mark- och vattenteknik), Kungliga Tekniskan högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4775.
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Osman, Mohamad Hussein. "Mathematical modelling and simulation of biofuel cells." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/363762/.
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Bio-fuel cells are driven by diverse and abundant bio-fuels and biological catalysts. The production/consumption cycle of bio-fuels is considered to be carbon neutral and, in principle, more sustainable than that of conventional fuel cells. The cost benefits over traditional precious-metal catalysts, and the mild operating conditions represent further advantages. It is important that mathematical models are developed to reduce the burden on laboratory based testing and accelerate the development of practical systems. In this study, recent key developments in bio-fuel cell technology are reviewed and two different approaches to modelling biofuel cells are presented, a detailed physics-based approach, and a data-driven regression model. The current scientific and engineering challenges involved in developing practical bio-fuel cell systems are described, particularly in relation to a fundamental understanding of the reaction environment, the performance and stability requirements, modularity and scalability. New materials and methods for the immobilization of enzymes and mediators on electrodes are examined, in relation to performance characteristics and stability. Fuels, mediators and enzymes used (anode and cathode), as well as the cell configurations employed are discussed. New developments in microbial fuel cell technologies are reviewed in the context of fuel sources, electron transfer mechanisms, anode materials and enhanced O2 reduction. Multi-dimensional steady-state and dynamic models of two enzymatic glucose/air fuel cells are presented. Detailed mass and charge balances are combined with a model for the reaction mechanism in the electrodes. The models are validated against experimental results. The dynamic performance under different cell voltages is simulated and the evolution of the system is described. Parametric studies are performed to investigate the effect of various operating conditions. A data-driven model, based on a reduced-basis form of Gaussian process regression, is also presented and tested. The improved computational efficiency of data-driven models makes them better candidates for modelling large complex systems.
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Richards, Kathryn. "Computational modelling of pollution dispersion in the near wake of a vehicle." Thesis, University of Nottingham, 2003. http://eprints.nottingham.ac.uk/10108/.
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The feasibility of using CFD to model the dispersion of pollutant in the near wake of a model vehicle was investigated through a series of experimental and computational studies. The near wake structure of the MIRA 33% scale reference vehicle (fastback) was measured using Particle Image Velocimetry (PIV), and hotwire anemometry and the dispersion of a tracer measured using Flame Ionisation Detectors (FIDs). The experimental data not only provided insight into the dispersion character of the model vehicles's near wake but more importantly produced data for the validation of the numerical simulations of the measured near wake and dispersion fields. The numerical simulations of the near wake flow field were conducted using the CFD code STAR-CD with the standard, RNG, Chen and nonlinear (quadratic) k- e models in combination with Upwind (UD), Linear Upwind (LUD) and the Monotone Advection and Reconstruction (MARS) differencing schemes. Validation showed the predicted flow field to be in good agreement with the measured flow field. Using the numerical flow field predictions as a foundation the dispersion of a passive gaseous pollutant was simulated by modelling the dispersion of scalar quantity released into the computational domain using a fluid injection technique. The numerical predictions of both mean velocity and concentration fields were validated against the experimental data using various statistical validation techniques. Several short investigations into the influence of vehicle speed and exhaust mass flow rate were also conducted to further assess the applicability and use of the technique in investigating dispersion in the near wake of a vehicle. Relative successes in both the velocity field and dispersion simulations were demonstrated in making predictions of the mean velocity and concentration fields. However there is clearly the need for more development and in particular the application of time-dependent techniques for the underlying velocity solutions in order that peaks in mean concentration resulting from build-up due to unsteadiness in the flow field are fully captured. Nevertheless the study demonstrated the potential for the use of STAR-CD to investigate and understand in more detail the dispersion of pollution close behind a road vehicle and possibly assess the concentration levels, at the road side of different pollutants released.
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Hutchings, Theresa. "Application of modelling techniques to test hypotheses concerning the migration of aviation gasoline from a surface spill." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/38732.
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Harries, Tom. "Physical testing and numerical modelling of a novel vertical-axis tidal stream turbine." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/66145/.
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A combination of climate change, due to anthropogenic CO2 emissions and concerns over energy security, due to fluctuating fuel prices, has led to the UK pushing to increase its renewable energy production. Harnessing tidal stream energy is an infant sector in the UK’s renewable energy portfolio, despite the UK’s large tidal stream resource, and is harnessed through deploying tidal stream energy converters. This thesis focuses on the design of a novel vertical axis tidal turbine (VATT) called CarBine which is driven by drag force and therefore has several unique advantages, including slow rotational speed, omni-directionality and a simple design. This research focused on the optimisation of the CarBine design and was split into two areas: physical testing and numerical modelling. A conventional Savonius was also analysed in both of these respects and this enabled a direct comparison of CarBine to a competing drag force driven VATT. Physical testing measured the power of the turbines and was conducted in hydraulic flumes at both Cardiff University (CU) and IFREMER in Northern France for a range of flow conditions. Testing at IFREMER enabled the quantification of the blockage effect in the CU experiments. Physical testing resulted in the optimised design of CarBine being one with a four arm configuration. From physical testing at CU, CarBine showed inferior efficiency performance to that of the conventional Savonius, a Cp of 0.117 compared to 0.225 at U∞=0.72 m/s. As a result a hybrid of both the Savonius and CarBine was tested, namely a Savonius with flaps. However, results from physical testing showed the Savonius with flaps to have inferior performance to both CarBine and the conventional Savonius, with a Cp of 0.103 at U∞=0.72 m/s at CU. Numerical modelling was conducted using the commercial CFD software package, Ansys CFX. Both transient and steady state simulations along with 2D and 3D models were used to model both CarBine and the Savonius. Both the k-ε and SST turbulence models were used for comparison. The two degrees of rotational freedom present in the CarBine design resulted in CarBine being difficult to model precisely. The numerical modelling results were validated against the physical testing results and where available, 3D results showed closer validation than the 2D results.
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Gao, Hongze. "Modelling geochemical interactions with groundwater transport processes : an application to acid mine drainage." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341885.
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Al, Mahaini Talal. "Radionuclide transport at the geosphere-biosphere interface : a combined measurements and modelling study." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/14417/.
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The aim of the present work was to improve the predictive capabilities of current modelling methods used to assess the long-term biosphere impacts of underground repositories for radioactive wastes. A number of issues related to parameter and conceptual uncertainties associated with compartmental biosphere models that simulate transport and accumulation of radionuclides in soils were addressed. The structure of compartmental models used for radiological risk assessments has not evolved noticeably over the past few decades and most of these models rely on simple assumptions. For example, compartmental models used to predict activity concentrations of radionuclides released into soils over very long timescales (typical of the lifetime of underground disposal repositories) assume arbitrary model specifications such as soil layer thickness (the vertical discretisation of the soil column) and length of the time step. Moreover, the majority of the available models assume invariant sorption characteristics of radionuclides with soil depth and hence employ constant solid-liquid distribution coefficient (Kd) values regardless of soil characteristics known to affect radionuclide sorption (e.g. pH, redox potential, moisture content and organic matter). The empirical Kd has a profound effect on long-term predictions of radionuclide behaviour in soil since it determines the degree of radionuclide retardation due to interaction with the soil. It is associated with considerable uncertainty due to differences in experimental conditions and methods used for its measurement and the variation in soil characteristics. In this study, three soil types (arable, grassland and woodland) were incubated under anaerobic conditions and the behaviour of naturally occurring selenium, iodine, rhenium and uranium, expressed as Kd, was investigated. The results indicate that variation in soil characteristics (e.g. moisture content, pH, mineral and organic carbon content) is a significant source of K, variability. Soils relatively higher in organic matter content (e.g. top soils) have higher sorptive capacities for trace elements than mineral subsoils and hence higher Kds. Dynamic, complex behaviour of K, under flooded, anaerobic soil condtions was measured over a 3 week period in soil microcosms. This dynamic behaviour was driven by the shift in soil redox potential which was associated with solubilisation of soil organic and mineral (Fe oxide) phases. Overall, the maximum observed variation in K, over the entire incubation period did not exceed 2 orders of magnitude. Biosphere models were constructed which combined a physically-based water flow model and the compartmental approach and used to simulate the long-term vertical distribution of radionuclides in the soil as well as radionuclide dynamics under different environmental conditions. Investigating radionuclide dynamics on a short timescale could only be achieved using models with a daily time step since short-term variation was obscured by a longer (annual) time step. Simulation results give insights into some of the limitations of available biosphere modelling methods for radiological risk assessment that are often overlooked. For example, soil radionuclide activity concentrations calculated using compartmental models are sensitive to the vertical discretisation (i.e. thickness of soil layers into which the soil column is divided) and time step of the model, hence the structure of the model should not be set arbitrarily. The discretisation procedure proposed in the present study may provide a useful framework to select the appropriate structure of biosphere assessment models. With respect to the effect of uncertainty in K, on model calculations, the results show that equilibrium timescales and radionuclide activity concentrations in the soil at equilibrium increase as the K, increases. For example, the time to reach steady state radionuclide activity concentrations in the vegetated topsoil increased 14-fold and 7-fold, respectively, when K, was increased 28-fold, which is a small variation compared to the uncertainty of Kd commonly reported in the literature (e.g. a few orders of magnitude). The Kd also affects short and long-term radionuclide dynamics in soils; the activity concentration of a radionuclide with low Kd (weakly sorbing) is more responsive to seasonal fluctuations in climatic and hydrological conditions than a radionuclide with a large Kd (strongly sorbing). Radionuclide uptake by plant roots, especially those which access highly contaminated soil layers adjacent to the contaminated aquifer, could be an important mechanism that provides a direct pathway between shallow, contaminated aquifers and the soil surface where elavated contamination poses greater risks.
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Zahran, El-Said Mamdouh Mahmoud. "Modelling and visualisation to support decision-making in air quality-related transport planning." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/13539/.
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This thesis introduces three main elements to support decision-making in air quality-related transport planning. The first are novel automatic collection and processing algorithms for traffic flow and geospatial data for input to air pollution models of transport schemes under analysis. The second is a novel strategy to improve the modelling of air quality by the calibration of input background concentrations. The third is a novel 3D air pollution dispersion interface for the 3D visualisation of the air quality predictions in 3D digital city models. Four urban transport schemes were used for the initial development of, and for testing, the applicability and validation of future air quality predictions of the decision-support system based on the above three elements. The automation of the input data collection and processing reduced significantly the time and effort required to set up the air pollution model. The calibration of background concentrations significantly improved the accuracy of, not only the annual mean, but also the hourly, air quality predictions and effectively reduced the model runtime. The 3D air pollution dispersion interface provided an intuitive 3D visualisation of the air quality predictions at and above the ground surface in a single 3D virtual scene. The application of this decision-support system enabled the development of alternative future traffic scenarios so a proposed urban transport scheme might contribute to achieving certain air quality objectives. The validation of the future air quality predictions showed that the methods used for the future projection of air pollution input data slightly increase the error between the modelled and actual annual mean NO2 future concentrations. They also significantly increase the error between the modelled and actual hourly NO2 future concentrations
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Duwahir, Zahras Mohamed. "Capturing CO2 from an integrated steel mill : a techno-economic analysis through process modelling." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32403/.
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The increase in global carbon dioxide emission has raised concerns about climate change. This has caused nations to consider different carbon dioxide mitigation pathways to reduce emissions. The iron and steel industry contributes to approximately 30% of total global CO2 direct emission in the industrial sector. It is an energy intense industry. Many steel mills are operating close to thermodynamic limits in efficiency. Therefore decarbonising the steel industry through process improvements is limited. Breakthrough technologies such as carbon capture and storage (CCS) is an alternative and attractive solution. In this research I have explored the application of a retrofit carbon capture technology to an existing steel mill. The steel mill chosen, combusts gases arising from the steel making processes. Different locations within the steel mill were analysed, the in-house power station and the turbo blower house were chosen for retrofit post-combustion carbon capture. Two different separation technologies were process modelled to capture the carbon dioxide from the flue gas of the in-house power station and the turbo blower house. The technologies were chemical absorption and adsorption. The two technologies were techno-economically studied. Chemical absorption, with solvent MEA, showed capability of recovering 86% of CO2 with a purity of more than 99 mol%. Adsorption using sorbent zeolite 13X was able to achieve 82% recovery with purity of 96 mol%. Sorbent activated carbon showed a capability of recovering 67% of carbon dioxide with a purity of 95 mol%. The cost of CO2 avoidance for the process using chemical absorption (MEA) was equal to $44.92/tonne CO2. For the process using adsorption (zeolite 13X) the CO2 avoided cost was equal to $44.90/tonne of CO2. Activated carbon was the most expensive capture process, out of the three processes studied. It costs $45.81/tonne of CO2 avoidance.
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Jenidi, Youla. "Bioremediation of estrone from water matrices using the enzyme laccase combined with mathematical modelling." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/42868/.
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The presence and impact of steroid estrogens in natural water matrices has driven development and evaluation of wastewater treatment technologies that may reduce the steroid load entering water environments. This work was undertaken to assess and predict the ability of Trametes versicolor laccase to degrade estrone (E1) in water matrices under realistic conditions to wastewater treatment plants (WWTPs) and with consideration of the complex and variable nature of the wastewater matrix. A robust experimental procedure was developed to ensure the efficiency of the enzyme laccase to degrade E1 in water matrices was not overestimated due to errors arising from poor experimental design. These experiments demonstrated that commercially-obtained laccase in concentrations above > 1 mg/ml are inhomogeneous requiring centrifugation prior to use to reduce error and provide more accurate evaluation of laccase capability. Sample filtration, which is necessary for chromatographic analysis, identified regenerated cellulose (RC) membrane filters as the optimum filters for particulates removal from E1 solutions due to their low affinity toward E1 (3.2 ±1.72 %). An optimum enzyme inactivation procedure using hydrochloric acid was also developed to ensure that the enzyme laccase was instantly inactivated without affecting the target steroid E1 itself. Using the established experimental procedure, bench-scale studies evaluating the efficiency of laccase-based treatment in a ‘clean’ water matrix were investigated. Experiments in deionised water provided a proof of concept of laccase ability to degrade E1 in water under realistic ranges of temperature [6˚C - 25˚C] and contact time [0.5 hr – 8 hrs] to the WWTP and evaluate the use of models to fit experimental data and predict within that system. Box Behnken Design (BBD) was applied to determine the number and the conditions of the performed experiments. The experimental data was then utilised to build two different models to predict E1 removal efficiency under any set of conditions and optimise the performance of laccase-based treatment system. The goodness of the fit for each model was tested using statistical indices such as coefficient of determination (R2), mean squared error (MSE) and absolute average deviation (AAD). The artificial neural network (ANN) model showed a better fit to the experimental data than the response surface methodology (RSM) model (RSM and ANN of R2 = 0.9908 and R2 = 0.9992 respectively. In addition, the predictive capabilities of RSM and ANN were tested using a set of statistically designed unseen data that was not previously used in models’ training. Both models showed limited predictive capabilities. The ability of laccase-based treatment to remove E1 in real-world wastewater was studied at bench scale. To account for the complexity and variability of the wastewater matrix, effluent samples during the period December 2014 - June 2015 were characterised for standard water quality parameters, where the temporal variation in wastewater chemical oxygen demand (COD), total suspended solids (TSS) and pH, were observed. A new water quality parameter, “Benchmark” was also developed and applied to quantify the impact of wastewater variability on laccase performance for E1 removal. The average benchmark value in the period between December 2014 and June 2015 was 79.8±3.7%. In addition, the impact of laccase inhibitors, which are likely to be present within the wastewater matrix, such as chloride, copper, iron and zinc, on laccase activity was investigated. The inhibitory effect of chloride ions increased with increasing chloride concentration above 200 mg/l. Copper and zinc ions exhibited negative effects on the enzymatic degradation of E1 at concentrations equal or above 10 mg/l and 200 mg/l. The impact of water matrix temperature, contact time and laccase concentration were studied in wastewater effluent and the experimental data was used to build RSM and ANN models. The predictive capability of the generated RSM model was relatively poor (R2 = 0.863) and even lower than the achieved predictive capability in clean matrix when tested using unseen data, this was partially attributed to the variability of wastewater matrix that could have not been addressed in this type of models. Whilst the improved ANN model showed a better predictive capability than RSM (R2=0.991) An advantage of the ANN model compared to the RSM model and reported for the first time, was the ability to include the impact of matrix complexity and variability on laccase performance, assessed via the benchmark data added as a forth factor in the ANN model. The final ANN model incorporating the matrix variability observed temporally during the sampling period had extremely high predictive capabilities (R2 > 0.99). This model approach holds the potential to help researchers evaluate and optimise laccase-based treatment (as well as other treatment technologies) and predict the removal efficiency of various bioactive chemicals under a wide range of conditions. Performing laccase-based treatment in a continuous reactor, utilising actual wastewater effluent and under realistic conditions to WWTPs, is the next stage that should be investigated in detail.
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Ali, Jafar. "Modelling of thermal plume discharge into shallow and still water." Thesis, University of Huddersfield, 2011. http://eprints.hud.ac.uk/id/eprint/11118/.
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The concerns of global warming are guiding most industries and commercial properties towards addressing their energy usage. In large buildings where air conditioning is required, there is often a need for “chillers” to control the temperature of the building. This process is not environmentally friendly and expensive in terms of energy used and maintenance issues. The alternative is to cool buildings using natural resources such as induced wind drafts and water extraction from rivers and canal. The latter has not been used with optimum effectiveness because the prediction procedures are not sufficiently developed to satisfy environmental legislation. The mathematical approaches are unrealistic and extremely conservative in their analysis and this causes many valid proposals to be rejected. This research is aimed at addressing that situation. It will provide a valid interactive 3-dimensional analysis procedure that will better evaluate the potential of using any British Waterways canal or similar water source for cooling purposes. After water has been used for cooling it is returned to the canal in a heated state as a thermal plume. It is the boundaries of the plume that must be predicted with reasonable accuracy so that environmental legislation is not infringed and livestock is not jeopardised. It is equally important to ensure the analysis is not over sensitive so as to result in rejection of valid proposals. Earlier work studied heat distribution but did not consider the thermal discharge into still and shallow water, as in a British Waterways canal. The studies below investigate several canal sites to evaluate a variety of situations where the discharge plume differs. Criteria including discharge direction, volume of water, temperature differences, speed of discharge and depth of discharge pipe all play a part in the formation of the plume. As such it is possible to develop an understanding of how the thermal plume merges into the still water and how the heat is diffused into the general body of water. In conjunction with site measurements a laboratory experimental scale model tank was built to replicate the real canal site. This allowed data to be varied and measured more readily. Two different types of discharge have been the subject of this research - the first being when the discharge pipe is located at the surface of the receiving water, the second being when it is submerged deeply below the surface. In all cases the temperature and velocity are measured at various points and at a variety of depths to provide a three dimensional plot across the mixing zone. In addition to the mathematical analysis, thermal imaging was used to predict the heat diffusion profiles on the surface of the receiving water in both the canal site and the model tank. CFD software is also used to evaluate the distribution of temperature and velocity within the mixing zone. The mathematical analysis produced an equation to predict the heat diffusion profile in surface discharge. And a number of equations were produced to model the plume path line in submerged discharge- relating to temperature and velocity dilution along and across the path lines. The relative effects of the bed and free surface proximity appeared significantly in the equations. A 3-dimensional model of the size of the plume is presented to demonstrate the results. The procedure followed in this study will enable the Environment Agency personnel to assess the waste heat utilization with greater thoroughness and within a shorter period.
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Yamana, Teresa K. (Teresa Keiko). "Mechanistic modelling of the links between environment, mosquitoes and malaria transmission in the current and future climates of West Africa." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97756.
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Thesis: Ph. D. in the Field of Hydrology, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 275-297).
Malaria transmission in West Africa is closely tied to climate, as rain fed water pools provide breeding habitat for the anopheles mosquito vector, and temperature affects the mosquito's ability to spread disease. This thesis presents a framework of highly detailed, spatially explicit mechanistic modelling to explore the relationships between the environment and malaria in the current and future climate of West Africa. A mechanistic model of human immunity was incorporated into an existing agent-based model of malaria transmission, allowing us to move beyond entomological measures such as mosquito density and vectorial capacity to analyzing the prevalence of the malaria parasite within human populations. The result is a novel modelling tool that mechanistically simulates all of the key processes linking environment to malaria transmission. Simulations were conducted across climate zones in West Africa, linking temperature and rainfall to entomological and epidemiological variables with a focus on nonlinearities due to threshold effects and interannual variability. Comparisons to observations from the region confirmed that the model provides a reasonable representation of the entomological and epidemiological conditions in this region. While current generation climate models agree that mean temperatures in West Africa will likely increase by 2 to 4° C in the future by the end of the 21st century, they disagree on the magnitude and the direction of the change in rainfall. We analyzed the performance of CMIP5 climate models in simulating West African rainfall and temperature before selecting the most credible predictions of future climate. We used these predictions to simulate the expected change in malaria transmission in sensitive regions of West Africa. We found that the western subregion of West Africa is likely to become drier in the coming decades. The warmer temperatures will shorten mosquito life spans, and the drying will limit mosquito reproduction. As a result, we expect malaria transmission in this region to decrease. However, the eastern half of the region is expected to become wetter. In some areas, the positive effects of increased rainfall on mosquito reproduction may surpass the negative effects of high temperatures on mosquito longevity, leading to a small net increase in environmental suitability for malaria transmission.
by Teresa K. Yamana.
Ph. D. in the Field of Hydrology
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Nota, Nomakhwezi Kumbuzile Constance. "Estimated environmental risks of engineered nanomaterials in Gauteng." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6809.
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Clemente, Andres. "Design and modelling of a photovoltaic driven fan solar air heater for drying woodchip in Scotland." Thesis, Edinburgh Napier University, 2011. http://researchrepository.napier.ac.uk/Output/4417.
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In the wood fuel supply chain, the water contained in the product determines one aspect of the quality of the wood. It is necessary to reduce the moisture content (MC) of the wood in order to reduce transport and storing costs and also to increase the heating value of the wood. In this thesis a solar thermal application has been developed to dry woodchips using exclusively solar energy. The novel solar woodchip dryer comprises a small woodchip dryer and a solar air thermal system (SATS) to increase the temperature of the drying air. The particularity of this woodchip dryer is that the input air flow is governed by a photovoltaic driven fan. Based on the experimental results obtained, the woodchip dryer and the SATS thermal performance were modelled and a simulation tool for predicting the dried woodchip production during a period of time has been developed. Two small capacity dryers, a thin and a thick layer dryer, have been designed and built to dry woodchip based on the flow capacity of the SATS. The drying performances are studied for both configurations comparing the drying times, drying rates and efficiencies at different test conditions. The drying curves obtained from each test are modelled as a function of key parameters, temperature and velocity employing the Page model equation. Based on the experimental results, a drying model has been successfully developed to predict the MC when the woodchip dryer operates within a range of drying conditions. A quantitative and qualitative analysis of the SATS thermal performance has been conducted employing various solar air collector configurations under Scottish weather conditions. The pneumatic characteristics of the solar dryer including the dryer are determining for the analysis of the system performance. Because of the PV driven fan electrical characteristics, the SATS presents a unique operation regime in which air flow depends exclusively on solar radiation. Thus the SATS thermal performance has been successfully modelled as a function of irradiance. The study necessarily includes the effect of environmental factors such as wind and cloudiness in the transient regime. The potential of using a solar woodchip dryer has been assessed based on the results obtained from modelling the dryer and the SATS together. The feasibility and employability of using the solar dryer for drying woodchips is discussed considering the productivity, the energy savings, costs and integration.
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Ramli, Nabilah Binti. "Analytical modelling of sound transmission in a lined duct." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/361186/.
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The focus of this thesis is on the prediction of sound attenuation through a lined duct, based on a mathematical model. Ducts with a single section as well as multi-segmented sections are discussed. The duct of interest has a rectangular cross-section as normally used for ventilation purposes. The mean flow in a ventilation duct is very low and can be neglected. In this thesis, two-dimensional analytical models are developed for sound transmission in a series of different duct configurations. Two models of the lining behaviour are considered, either locally-reacting or bulk-reacting. The models are used first to obtain the transverse and axial wavenumbers of various modes of the duct. The required finite numbers of wavenumbers are tracked using Müller’s method. The wavenumbers are traced from a very low frequency to high frequency using small frequency steps. It is found that, for a duct with a bulk-reacting lining, the number of modes with a transverse wavenumber below a particular value may exceed the corresponding number of modes in a duct with a locally-reacting lining. These additional modes are termed lining modes. The number of lining modes depends on the lining thickness. Dispersion curves are presented for both types of lining. The transmission of sound through the duct is then calculated using the mode-matching technique. The mode-matching model allows analysis of multi-modal wave propagation in the duct. The model is first developed for an infinitely long rigid duct with a finite length of lined insert. The estimation from the locally reacting model, that is widely available in the literature, is compared with the estimation from the newly developed bulk-reacting model. Although the locally reacting model often overestimates the performance of a bulk-reacting lining it is found that this is not always the case, especially for a small lining thickness and at lower frequencies where the locally reacting model may under-estimate the performance. The analytical model is then extended to a multi-segmented lining where the lined section is uniformly segmented with rigid walled sections in a periodic manner. For a bulk-reacting lining, the segmented arrangement renders the lining more similar to the behaviour of a duct with a locally-reacting lining and improves the peak attenuation. Little improvement is found in the case of a multi-segmented locally-reacting lining. The effect of duct height, lining thickness and lining flow resistivity on sound attenuation is studied using the analytical model. Experiments are presented which validate the analytical model.
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Jordan, Gyözö. "Terrain Modelling with GIS for Tectonic Geomorphology : Numerical Methods and Applications." Doctoral thesis, Uppsala universitet, Miljö- och landskapsdynamik, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4635.
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Analysis of digital elevation models (DEMs) by means of geomorphometry provides means of recognising fractures and characterising the morphotectonics of an area in a quantitative way. The objective of the thesis is to develop numerical methods and a consistent GIS methodology for tectonic geomorphology and apply it to test sites. Based on the study of landforms related to faults, geomorphological characteristics are translated into mathematical and numerical algorithms. The methodology is based on general geomorphometry. In this study, the basic geometric attributes (elevation, slope, aspect and curvatures) are complemented with the automatic extraction of ridge and valley lines and surface specific points. Evan’s univariate and bivariate methodology of general geomorphometry is extended with texture (spatial) analysis methods such as trend, autocorrelation, spectral, wavelet and network analysis. Digital terrain modelling is carried out by means of (1) general geomorphometry, (2) digital drainage network analysis, (3) digital image processing, (4) lineament extraction and analysis, (5) spatial and statistical analysis and (6) DEM specific digital methods such as shaded relief models, digital cross-sections and 3D surface modelling. Geological data of various sources and scales are integrated in a GIS database. Interpretation of multi-source information confirmed the findings of digital morphotectonic investigation. A simple shear model with principal displacement zone in the NE-SW direction can explain most of the morphotectonic features associated with structures identified by geological and digital morphotectonic investigations in the Kali Basin. Comparison of the results of the DTA with the known geology from NW Greece indicated that the major faults correspond to clear lineaments. Thus, DTA of an area in the proposed way forms a useful tool to identify major and minor structures covering large areas. In this thesis, numerical methods for drainage network extraction and aspect analysis have been developed and applied to tectonic geomorphology.
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Demetriades, Thomas A. "Modelling CO₂ transport and the effect of impurities : a new equation of state for CCS pipeline transport." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/14456/.
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In this EngD project I developed a new, analytic equation of state for use in the area of CCS pipeline transport. It was my aim to design a model which would exhibit a high degree of accuracy within the anticipated window of operation of CCS pipelines; from 260 to 335K and 1 to 200bar, whilst simultaneously retaining a simplicity and ease-of-use, a lack of which made some other available equations particularly unwieldy. Having conducted a comprehensive literature review and attended many academic and industrial conferences throughout this project, I felt that there was a need for an equation of state which could perform both these functions. This was the key motivation for my work, and the model presented in this thesis was developed in order that it might contribute towards negating the many concerns that currently surround the pipeline transport stage of CCS. I aimed for the proposed model to display a complexity approaching that of some of the simpler equations currently available, whilst incorporating sucient flexibility to give thermodynamic predictions to a standard approaching that of those which are more complicated. I defined criteria by which the proposed model could be judged, so that it could be applied with condence in the determination of the physical properties of carbon dioxide mixtures during CCS pipeline transport. Work was carried out by fitting the parameters of the proposed model to experimental data gathered from the literature, so that it would be able to determine the homogeneous phase pressure and vapour-liquid equilibrium behaviour of carbon dioxide and other relevant gas mixtures. The project yielded a number of excellent outputs, not least the satisfaction of the primary aim which was the proposal of a model, which through this EngD, I demonstrated had the ability to meet the demands that were set. In carrying out this work, I also developed several highly useful auxiliary mathematical methods which helped in ensuring the proposed model was as accurate as possible. For the case of modelling pure carbon dioxide, the proposed equation worked exceptionally well, providing highly accurate predictions for homogeneous density and vapour liquid equilibrium, which were well within the targets set. A paper on this was published in May 2013. In extending the model to incorporate some binary mixtures I again found that it demonstrated a clear ability to capture the necessary physical behaviours within the target range. I concluded with suggestions as to ways in which the work presented here could be developed further, as well as the many avenues for future work in other areas that this EngD project had opened up.
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Al-Ayfari, Hadi H. K. "Experimental measurement and mathematical modelling of meteorological parameters for solar energy applications." Thesis, University of Birmingham, 1986. http://etheses.bham.ac.uk//id/eprint/5888/.
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A new meteorological research station has been established and set up in the Solar Energy Laboratory which measures solar radiation (total and diffuse) on a horizontal surface, ambient air temperature, wind speed and wind direction. An inexpensive data logger based on an APPLE II microcomputer was designed and built. This data logger was used for more than 21 months and provided processed data for transcribing onto a main frame computer. A microdata (M1600L) microprocessor based automatic data logger was used later for the continuous monitoring of measured parameters. Four years of monitored data were used for analysis. Two mathematical models have been developed for the estimation of both total and diffuse solar radiation on a horizontal surface from different meteorological parameters. Several mathematical models developed by others were used to relate solar radiation and meteorological parameters measured in Birmingham. The results of these were compared, analysed and the best six were identified. The best models were tested and evaluated with (a) Birmingham data, (b) data from nine different sites in Europe. The best results show that the Birmingham models give the best estimation for total and diffuse solar radiation. The work reported here forms part of a continuous project of the Solar Energy Laboratory in meteorological research applied to solar energy utilization.
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Jafary, Forough. "Participatory modelling platform for groundwater irrigation management with local farmers in Iran (Kashan)." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6809/.
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This thesis develops a participatory modelling process to study improvement in the management of irrigation efficiency, including physical and social dimensions in the context of arid and semi-arid regions of Iran. This study develops an interdisciplinary and participatory method to understand and strengthen collective decision-making in local Iranian farming systems. Specific attention is given to groundwater irrigated agricultural practices under the Iranian governance system to provide wider context. Kashan City, in central Iran is selected as a case study area for specific reasons, such as historical water use, the farmers’ rich indigenous knowledge, and successful agricultural practices under conditions of water scarcity. The accessibility and willingness of local farmers to engage in a participatory modelling process are considered. The thesis suggests the first use of role-play simulation for irrigation management practices in Iran, is an effective and insightful method of achieving adaptive management solutions. The application of an innovative participatory simulation modelling with farmers revealed their main incentives for collective irrigation practices, their capabilities to learn and evaluate the system. It is argued that management decisions have major impacts on farmers’ livelihoods and therefore it is essential to integrate farmers’ perspectives in local governance to sustain agricultural productivity.
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Sawatmongkhon, Boonlue. "Modelling of catalytic aftertreatment of NOx emissions using hydrocarbon as a reductant." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3138/.
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Hydrocarbon selective catalytic reduction (HC-SCR) is emerging as one of the most practical methods for the removal of nitrogen oxides (NOx) from light-duty-diesel engine exhaust gas. In order to further promote the chemical reactions of NOx-SCR by hydrocarbons, an understanding of the HC-SCR process at the molecular level is necessary. In the present work, a novel surface-reaction mechanism for HC-SCR is set up with emphasis on microkinetic analysis aiming to investigate the chemical behaviour during the process at a molecular level via detailed elementary reaction steps. Propane (C3H8) is chosen as the reductant of HC-SCR. The simulation is designed for a single channel of a monolith, typical for automotive catalytic converters, coated with a silver alumina catalyst (Ag/Al2O3). The complicated physical and chemical details occurring in the catalytic converter are investigated by using the numerical method of computational fluid dynamics (CFD) coupled with the mechanism. The C3H8-SCR reaction mechanism consists of 94 elementary reactions, 24 gas-phase species and 24 adsorbed surface species. The mechanism is optimised by tuning some important reaction parameters against some measurable data from experiments. The optimised mechanism then is validated with another set of experimental data. The numerical simulation shows good agreements between the modelling and the experimental data. Finally, the numerical modelling also provides information that is difficult to measure for example, gas-phase concentration distribution, temperature profiles, wall temperatures and the occupation of adsorbed species on catalyst surface. Consequently, computational modelling can be used as an effective tool to design and/or optimise the catalytic exhaust aftertreatment system.
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Grubliauskas, Raimondas. "Research and Digital Modelling of Environmental Noise and its Reduction by applying Light Structures." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090713_161749-77904.
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General characteristic of the dissertation
Problem of the work. With a rapid development of industrialisation and urbanisation, the environmental pollution has greatly increased. Upon automating the manufacturing industry and agriculture, with traffic flows in towns and residential areas increasing and household equipment becoming more modern, the number of acoustic discomfort zones is rapidly growing.
People are exposed to noise not only at workplaces abut also on the streets and at home. As maintained by doctors, noise reduces immunity of the organism and, as a source of chronic stress, has an adverse effect on the central nervous system and causes various health disorders. Even a relatively low noise of 60–70 dB causes a headache, dizziness, squeak in the ears, insomnia, and worsens memory, attention and orientation. A noisy environment reduces working efficiency, reaction speed, movement coordination and increases nervous strain and a risk of traumas.
The noise dispersed by stationary sources may be reduced by replacing components with less sounding ones, applying rubber, plastic or other materials on the surface of installations. If it is impossible to reduce noise in the place of its generation, hoods are fitted out, premises are insulated and noise suppressing systems are used (noise reducing barriers, volumetric noise absorbers, wall insulation with noise-proof materials).
The dispersion of traffic-generated noise is reduced by noise suppression walls, green... [to full text]Tiriamoji problema. Šiandieniniame gyvenime, mechanizavus pramonės ir žemės ūkio gamybą, didėjant transporto srautams miestuose ir gyvenvietėse, modernėjant buitinei technikai, sparčiai plečiasi padidinto triukšmo zonos. Medikai teigia, kad triukšmas mažina organizmo imuninį atsparumą ir įspėja, kad triukšmas, kaip lėtinis streso šaltinis, veikia centrinę nervų sistemą ir kelia įvairių sveikatos sutrikimų. Net palyginus nestiprus 60 – 70 dB triukšmas kelia galvos skausmus, nemigą, pablogėja atmintis, dėmesys, darbingumas. Stacionarių šaltinių skleidžiamas triukšmas sumažinamas keičiant detales keičiant, padengiant įrenginių paviršių guma, plastmase ir kt. Jeigu neįmanoma sumažinti triukšmo ten, kur jis kyla, įrengiami gaubtai, izoliuojamos patalpos, bei taikomos garsą slopinančios sistemos (triukšmą mažinantys barjerai, tūriniai garso sugėrikliai, sienos dengiamos garsą izoliuojančia medžiaga). Transporto keliamo triukšmą sklaidą mažina triukšmo slopinimo sienelės, želdiniai, pastatai. Taip pat veiksmingi būdai yra transporto greičio apribojimas, kelių dangos paviršiaus keitimas, eismo ribojimas ir reguliavimas. Inžineriniai sprendimai būna pigesni, jei įvertinami architektūrinio planavimo stadijoje. Nagrinėjant triukšmo mažinimo priemonių bei metodų įgyvendinimo galimybę, ypač svarbus skaitinis triukšmo sklaidos modeliavimas. Darbo aktualumas. Įvairūs technologiniai procesai kelia triukšmą. Leistini triukšmo lygiai viršijami ne tik darbo vietose ar įmonės teritorijose... [toliau žr. visą tekstą]
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Abdul, Hamid Nor Hazren. "Development of new mathematical modelling for remediation process : case studies on remediation of copper from water matrices using cellulose nanowhisker adsorbents." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/43316/.
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Metal pollutants such as copper released into the aqueous environment have been increasing as a result of anthropogenic activities, a topic causing global concern. Adsorption-based treatment technologies offer opportunities to remediate metal pollutants from municipal and industrial wastewater effluent. The aim of this work was to evaluate the capability of modified cellulose nanowhisker (CNW) adsorbents for the remediation of copper from water matrices under realistic conditions using response surface methodology (RSM) and artificial neural network (ANN) models. The first part of the study explored the preparation and characterisation of modified CNW adsorbents. It also focused on the stability of the modified CNW adsorbents at different time intervals under dry conditions (up to 28 days) and in the water matrix (up to 7 days). The results showed that the modified CNW adsorbents were stable at different time intervals under dry conditions and in the water matrix and proved that the functional groups were permanent and did not degrade under the tested conditions. The stability of these modified CNW adsorbents under these conditions, which is relevant from both the manufacturing and application perspectives, is reported for the first time in this study. The second part of the work focused on using copper as a case study for heavy metal pollution in a clean water matrix, to evaluate removal by modified CNWs under several conditions and ranges appropriate to wastewater treatment plants (WWTPs), using factorial experimental design. RSM and ANN models were employed in order to optimise the system and to create a predictive model to evaluate the Cu(II) removal performance by the modified CNW adsorbents. Moreover, unseen experiments not belonging to the training data set, located both inside and outside the test parameter system, were performed to test the model suitability. This is also novel, as generally only one or two parameter variations have been tested, without checking the chosen model suitability for parameters lying between the tested parameters, and certainly not for parameters lying outside the tested parameter space, as has been done in this study. The results obtained showed that the ANN model outperformed the RSM model when predicting copper removal from a clean water matrix. The Langmuir andFreundlich isotherm models were applied to the equilibrium data, and the results revealed that the Langmuir isotherm (R2 = 0.9998) had better correlation than the Freundlich isotherm (R2 = 0.9461). Experimental data was also tested in terms of kinetics studies using pseudo-first order and pseudo-second order kinetic models. The results showed that the pseudo-second-order model accurately described the kinetics of adsorption. The third part of the work was aimed at gaining a deeper understanding of the complexity and variability of the wastewater matrix, including evaluating the impact of the wastewater matrix temporally on adsorbent performance to remediate copper pollutant from a real-world wastewater matrix. This study has demonstrated that the wastewater matrix composition, which is both complex and variable, has an impact on adsorbent capability and performance. A benchmark study was adopted as a ‘new’ water quality parameter to inform on the effects of the wastewater matrix (wastewater composition and its variability) on the modified CNW adsorbent’s capability to remediate copper from this matrix. Since the process of adsorption from wastewater is often complicated due to the variation in wastewater composition, results obtained from the benchmark experiments were included as one of the independent variables in ANN modelling, unlike in other optimisation studies. The performance of the ANN and RSM models was statistically evaluated in terms of coefficient of determination (R2), absolute average deviation (AAD), and root mean squared error (RMSE) on predicted experimental outcomes. The ANN model including the variability of wastewater composition fitted the experimental data with excellent accuracy and better prediction (R2 = 0.9963) than both the ANN model that did not include this variability (R2 = 0.9945), and the RSM model (R2 = 0.9409). The outcome of this study showed that by supplying the ANN model with the data obtained from the benchmark experiments as the fourth independent variable, it was possible to improve the predictability of the ANN model. Continuous flow experiments for remediation of spiked Cu(II) from the wastewater matrix were conducted. However, the physical structure of modified CNW adsorbents renders them unsuitable for use in column operation. Therefore, a more detailed study of the mechanical properties of CNW adsorbents would be necessary in order to improve the strength and stability of the adsorbents. This work has demonstrated that modified CNW are promising adsorbents to remediate copper from water matrices under realistic conditions including wastewater complexity and variability. The use of models to predict the test parameter system and account for matrix variability when evaluating CNW adsorbents for remediating Cu from a real-world wastewater matrix may also provide the foundation for assessing other treatment technologies in the future.
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Adams, Ethan. "PATHWAY CONNECTIVITY IN AN EPIGENETIC FLUVIOKARST SYSTEM: INSIGHT FROM A NUMERICAL MODELLING STUDY IN KENTUCKY USA." UKnowledge, 2019. https://uknowledge.uky.edu/ce_etds/88.
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Fluviokarst landscapes are dominated by both fluvial and karst features. Interpreting hydrologic pathways of fluviokarst can be confounded by the unknown connectivity of the various flow regimes. A combined discrete-continuum (CDC) hybrid numeric model for simulating the surface and subsurface hydrology and hydraulics in fluviokarst basins was formulated to investigate fluviokarst pathways. This model was applied to the Cane Run Royal Springs basin in Kentucky USA. A priori constraints on parameterization were avoided via multi-stage optimization utilizing Sobol sequencing and high performance computing. Modelling results provide evidence of hydrologic pathways dominated by fracture flow, epikarst transfer and runoff. Fractures in karst basins with high fracture-matrix permeability ratios may influence both springflow and streamflow. Swallet features can be as important as spring features as they are sink features in streamflow during hydrologic events. Inflections in spring hydrographs represent shifts in the surface-subsurface connectivity via the fractures, as opposed to shifts in dominant storage zones. Existing methods of dual- and triunal hydrograph separation of karst springflow may not be directly transferrable to fluviokarst springs. The numerical model herein has advantages of suggesting dominant pathways in complex terrane and highlighting unforeseen surface-subsurface connectivity. However, disadvantages include computational expense and previous site studies.
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Grazziotin, Pablo Colossi. "CityZoom UP (Urban Pollution) : a computational tool for the fast generation and setup of urban scenarios for CFD and dispersion modelling simulation." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37914/.
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This research presents the development of CityZoom UP, the first attempt to extend existing urban planning software in order to assist in modelling urban scenarios and setting up simulation parameters for Gaussian dispersion and CFD models. Based on the previous capabilities and graphic user interfaces of CityZoom to model and validate urban scenarios based on Master Plan regulations, new graphic user interfaces, automatic mesh generation and data conversion algorithms have been created to seamlessly generate input data for dispersion model AERMOD and CFD packages CFX and OpenFOAM. A key feature of CityZoom UP is the introduction of vehicular pollution source parameters in dispersion and CFD models, allowing the urban designer to assess the local impact of adding or modifying a building or group of buildings on the street air quality. Traffic emissions are modelled as sequence of point sources. CityZoom UP uses Atmospheric Dispersion model AERMOD to assess the dispersion of pollutants in large scale urban environments for strategic planning, quickly providing results for different alternatives of urban scenarios, meteorological and traffic profiles. Sensitivity and validation tests are performed and the results are compared to wind tunnel and real world tracer experiments from the DAPPLE campaign. For the first time in the available literature AERMOD is used to perform dispersion simulation using tracer emission data from mobile vehicular sources in a complex urban scenario, considering building wake effects. CityZoom UP also provides automated 3D meshing, including mesh refinement, identification of physical boundaries in the mesh, and automatic setup of CFD simulations of urban scenarios, for the detailed calculation of air flow and dispersion of pollutants in specific areas inserted in urban environments. These capabilities can greatly reduces the time necessary for the setup CFD cases, even if it does not affect the computational time needed to run the CFD simulations. Tests show how CityZoom UP can be used to model alternative scenarios for a given location, e.g. present situation and future scenario including a new tall building, and to easily automate the generation of different meshes for each scenario, based on boundary layer and size function refinement parameters. The present and possible future situations of a real world scenario in Porto Alegre are modelled as a show case for CityZoom UP. The capabilities to assist in modelling alternative urban scenarios and setting up AERMOD and CFD simulations based on those scenarios is demonstrated.
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Safwat, Amr M. "Stochastic Multimedia Modelling of Watershed-Scale Microbial Transport in Surface Water." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406880416.
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Forson, Francis Kofi. "Modelling and experimental investigation of a mixed-mode natural convection solar crop dryer (MNCSD)." Thesis, De Montfort University, 1999. http://hdl.handle.net/2086/4201.
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Scott, Sharon Elizabeth. "Computational Approaches to Studying Organic Cation Sorption to Organic Matter." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1594139918499603.
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Davison, Bruce. "Snow Accumulation in a Distributed Hydrological Model." Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/793.
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The cryosphere is defined as the portions of the earth where water is in solid form. It represents a very important part of the hydrologic cycle, affecting ecological, human and climate systems. A number of component models describing the energy and mass balances of a snowpack have been developed and these component models are finding their way into watershed models and land surface schemes. The purpose of this thesis is to examine the incorporation of a number of snow processes in the coupled land-surface-hydrological model WATCLASS.
The processes under consideration were mixed precipitation, variable fresh snow density, maximum snowpack density, canopy interception and snow-covered area (SCA). The first four of these processes were based on similar work done by Fassnacht (2000) on a watershed in Southern Ontario. In the case of this thesis, the work was completed on a basin in Northern Manitoba. A theory of the relationship between snow-covered area and average snow depth was developed and an algorithm was developed to implement this theory in WATCLASS. Of the five snow processes considered, mixed precipitation was found to have the greatest impact on streamflow while the new canopy interception algorithm was found to have the greatest impact on sensible and latent heat fluxes. The development of a new relationship between SCA and average snow depth was found to have a minimal impact in one study case, but a significant impact on the sensible and latent heat fluxes when snow fell on a pack that had begun to melt and was partially free of snow. Further study of these snow processes in land-surface-hydrologic models is recommended.
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Gullman, Isak. "Improved prediction of biogas production at Uddebo wastewater treatment plant : Substrate modelling in SIMCA." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-85463.
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Anaerobic digestion is a complex process, dependent on multiple factors, which can be made more stable and efficient with the help of process models. A more stable process could reduce biogas torching, which increases the amount of renewable energy available for heat- and electricity production and vehicle fuel. Fluctuations in the produced biogas at Uddebo WWTP in Luleå, Sweden, has been observed, where imported industrial waste was suspected to be the cause. The purpose of this master thesis was to increase the predictability of the biogas production at Uddebo WWTP by creating a process model based on historical data. The historical data consisted of quantitative data of the substrates loaded into the anaerobic digestor and biogas collected from the digestor. The results showed that the calculated error between modelled and measured biogas production was <20%, which was considered good. However, due to the demarcation of this report, many variables were ignored in the creation of the model. Further research is therefore a requirement for the model to function properly: The error should be reduced to <10%, This could be done by increasing the period and resolution toinclude and statistically secure fast and seasonal variations. make qualitative modelling easier, i.e., prediction of the biomethane amount in the biogas. The industrial liquid waste storage should be included in the calculation. A more detailed analysis of all substrates is needed to make the comparison between the literature based and measured production more realistic. Expanding the demarcation of the model to also include the environment in the digestor. This could also increase the total amount of biogas produced.
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Shirazi, Elham. "INVESTIGATION OF ATMOSPHERIC EFFECTS ON VAPOR INTRUSION PROCESSES USING MODELLING APPROACHES." UKnowledge, 2019. https://uknowledge.uky.edu/ce_etds/89.
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Most people in the United States (US) spend considerable amount of time indoors—about 90% of their time as compared to outdoors, which makes the US population vulnerable to adverse health effects of indoor air contaminants. Volatile organic compound (VOC) concentrations are well-known to be higher in indoor air than outdoor air. One source of VOC concentrations in indoor air that has gained considerable attention in public health and environmental regulatory communities is vapor intrusion. Vapor intrusion is the process by which subsurface vapors enter indoor spaces from contaminated soil and groundwater. It has been documented to cause indoor air contamination within hundreds of thousands of communities across the US. Vapor intrusion is well-known to be difficult to characterize because indoor air concentrations exhibit considerable temporal and spatial variability in homes throughout impacted communities. Unexplained variations in field data have not been systematically investigated using theoretical fate and transport processes. This study incorporates the use of numerical models to better understand processes that influence spatial and temporal variability in field data. The overall research hypothesis is that variability in indoor air VOC concentrations can be (partially) explained by variations in building air exchange rate (AER) and pressure differentials between indoor spaces and outdoor spaces. Neither AER nor pressure differentials are currently calculated by existing vapor intrusion numerical models. To date, most vapor intrusion models have focused on subsurface fate and transport processes; however, there is a need to understand the role of aboveground processes in the context of vapor intrusion exposure risks, which are commonly measured as indoor air VOC concentrations. Recent field studies identify these parameters as potentially important and their important role within the broader field of indoor air quality sciences has been well-documented, but more research is needed to investigate these parameters within the specific context of vapor intrusion. To test the overall hypothesis, the dissertation research developed a new vapor intrusion modeling technique that combines subsurface fate and transport modeling with building science approaches for modeling driving forces, such as wind and stack effects. The modeling results are compared with field data measurements from actual vapor intrusion sites and confirms that the research is relevant to not only academic researchers, but also policy decision makers.
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Sazib, Nazmus Shams. "Physically Based Modelling of the Impacts of Climate Change on Streamflow Regime." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/5067.
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Understanding the implications of climate change on streamflow regime is complex as changes in climate vary over space and time. However, a better understanding of the impact of climate change is required for identifying how stream ecosystems vulnerable to these changes, and ultimately to guide the development of robust strategies for reducing risk in the face of changing climatic conditions. Here I used physically based hydrologic modeling to improve understanding of how climate change may impact streamflow regimes and advance some of the cyberinfrastructure and GIS methodologies that support physically based hydrologic modeling by: (1) using a physically based model to examine the potential effects of climate change on ecologically relevant aspects of streamflow regime, (2) developing data services in support of input data preparation for physically based distributed hydrologic models, and (3) enhancing terrain analysis algorithms to support rapid watershed delineation over large area. TOPNET, a physically based hydrologic model was applied over eight watersheds across the U.S to assess the sensitivity and changes of the streamflow regime due to climate change. Distributed hydrologic models require diverse geospatial and time series inputs, the acquisition and preparation of which are labor intensive and difficult to reproduce. I developed web services to automate the input data preparation steps for a physically based distributed hydrological model to enable water scientist to spend less time processing input data. This input includes terrain analysis and watershed delineation over a large area. However, limitations of current terrain analysis tools are (1) some support only a limited set of specific raster and vector data formats, and (2) all that we know of require data to be in a projected coordinate system. I enhanced terrain analysis algorithms to extend their generality and support rapid, web-based watershed delineation services. Climate change studies help to improve the scientific foundation for conducting climate change impacts assessments, thus building the capacity of the water management community to understand and respond to climate change. Web-based data services and enhancements to terrain analysis algorithms to support rapid watershed delineation will impact a diverse community of researchers involved terrain analysis, hydrologic and environmental modeling.
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Kong, Dechao. "Advanced HVDC systems for renewable energy integration and power transmission : modelling and control for power system transient stability." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4217/.
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The first part is concerned with dynamic aggregated modelling of large offshore wind farms and their integration into power systems via VSC-HVDC links. The dynamic aggregated modelling of offshore wind farms including WT-DFIGs and WT-PMSGs are proposed to achieve effective representations of wind farms in terms of computational time and simulation accuracy for transient stability analysis. Modelling and control of VSC-HVDC systems for integration of offshore wind farms are investigated. Comparisons of two control schemes of rectifier-side converter are carried out to evaluate their dynamic performance for integration of these offshore wind farms in terms of transient stability. The second part is to address the advanced transmission systems with innovative HVDC configurations. Feasibility studies of updated schemes of monoplolar CSC-HVDC link with support of monopolar VSC-HVDC link as the hybrid bipolar CSC/I{VDC system is carried out to deal with two key issues of CSC-HVDC. Small-signal modelling of MTDC grids is investigated and parameter optimisation of PI controller of converters in MTDC grids is carried out using PSO method based on small-signal models of the system at multiple operating points to obtain optimised parameters of PI controllers to improve dynamic performance of MTDC grids at multiple operating points.
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Eriksson, Johanna. "Sensitivity analysis of pluvial flood modelling tools for dense urban areas : A case study in Lundby-Lindholmen, Gothenburg." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-80431.
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As a result of the global climate change, extreme precipitation is occurring more frequently which increases the risk of flooding, especially in urban areas. Urbanisation is widely discussed regarding urban flooding where an increase of impervious surfaces limits the infiltration and increases the surface runoff. Flooding events in urban areas are increasing around the world and can cause large damages on infrastructure and buildings, which makes the cities vulnerable. Urban flood models are an important tool for analysing the capacity of the drainage systems, to predict the extent of the events and to find optimal locations to implement measures to prevent damages from flooding. In this project, a sensitivity analysis in MIKE FLOOD, a coupled 1D-2D flood model developed by DHI is presented, where sewer- and surface systems are integrated. The aim with this project is to investigate how the result of a coupled flood model vary in relation to changes in input parameters. The sensitivity analysis is performed to evaluate how different parameters impact the model output in terms of water depth and variations in cost of flooded buildings, roads, rail- and tramways. The analysis is applied in a case study in Lundby-Lindholmen, Gothenburg city, Sweden. The results show that modelling without infiltration influenced the model output the most, with the largest increase both in terms of cost and water depth over the investigated area. Here the correlation between the initial water saturation and location of the applied pre-rain was highlighted. The model outputs were less sensitive to changes in surface roughness (expressed as Manning value) than without infiltration but did lead to measurable changes in surface water depth and distribution while the flood damage cost didn’t show any major changes. Additionally, the coupled flood model was evaluated in terms of handling changes in magnitudes of rain-events. Data indicates the shorter the return period, the smaller the flood propagation, as well as the flood damage cost decreases with shorter return periods. The data evaluated supports the use of this coupled model approach for shorter return periods in terms of flood propagation.