Дисертації з теми "Runoff Australia Mathematical models"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Runoff Australia Mathematical models.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Runoff Australia Mathematical models".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Goodrich, David Charles. "Basin Scale and Runoff Model Complexity." Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/614028.
Повний текст джерелаАнотація:
Distributed Rainfall-Runoff models are gaining widespread acceptance; yet, a
fundamental issue that must be addressed by all users of these models is definition
of an acceptable level of watershed discretization (geometric model complexity). The
level of geometric model complexity is a function of basin and climatic scales as well
as the availability of input and verification data. Equilibrium discharge storage is
employed to develop a quantitative methodology to define a level of geometric model
complexity commensurate with a specified level of model performance. Equilibrium
storage ratios are used to define the transition from overland to channel -dominated
flow response. The methodology is tested on four subcatchments in the USDA -ARS
Walnut Gulch Experimental Watershed in Southeastern Arizona. The catchments
cover a range of basins scales of over three orders of magnitude. This enabled a
unique assessment of watershed response behavior as a function of basin scale.
High quality, distributed, rainfall -runoff data was used to verify the model (KINEROSR). Excellent calibration and verification results provided confidence in
subsequent model interpretations regarding watershed response behavior. An
average elementary channel support area of roughly 15% of the total basin area is
shown to provide a watershed discretization level that maintains model performance
for basins ranging in size from 1.5 to 631 hectares. Detailed examination of
infiltration, including the role and impacts of incorporating small scale infiltration
variability in a distribution sense, into KINEROSR, over a range of soils and
climatic scales was also addressed. The impacts of infiltration and channel losses
on runoff response increase with increasing watershed scale as the relative influence
of storms is diminished in a semiarid environment such as Walnut Gulch. In this
semiarid environment, characterized by ephemeral streams, watershed runoff
response does not become more linear with increasing watershed scale but appears
to become more nonlinear.
2
Sorooshian, Soroosh, and Vijai Kumar Gupta. "Improving the Reliability of Compartmental Models: Case of Conceptual Hydrologic Rainfall-Runoff Models." Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/614011.
Повний текст джерела
3
Hendrickson, Jene Diane, and Soroosh Sorooshian. "CALIBRATION OF RAINFALL-RUNOFF MODELS USING GRADIENT-BASED ALGORITHMS AND ANALYTIC DERIVATIVES." Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1987. http://hdl.handle.net/10150/614186.
Повний текст джерелаАнотація:
In the past, derivative-based optimization algorithms have not
frequently been used to calibrate conceptual rainfall -riff (CRR)
models, partially due to difficulties associated with obtaining the
required derivatives. This research applies a recently- developed
technique of analytically computing derivatives of a CRR model to a
complex, widely -used CRR model. The resulting least squares response
surface was found to contain numerous discontinuities in the surface
and derivatives. However, the surface and its derivatives were found
to be everywhere finite, permitting the use of derivative -based
optimization algorithms. Finite difference numeric derivatives were
computed and found to be virtually identical to analytic derivatives.
A comparison was made between gradient (Newton- Raphsoz) and
direct (pattern search) optimization algorithms. The pattern search
algorithm was found to be more robust. The lower robustness of the
Newton-Raphsoi algorithm was thought to be due to discontinuities and a
rough texture of the response surface.
4
Kapangaziwiri, Evison. "Revised parameter estimation methods for the Pitman monthly rainfall-runoff model." Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1006172.
Повний текст джерелаАнотація:
In recent years, increased demands have been placed on hydrologists to find the most effective methods of making predictions of hydrologic variables in ungauged basins. A huge part of the southern African region is ungauged and, in gauged basins, the extent to which observed flows represent natural flows is unknown, given unquantified upstream activities. The need to exploit water resources for social and economic development, considered in the light of water scarcity forecasts for the region, makes the reliable quantification of water resources a priority. Contemporary approaches to the problem of hydrological prediction in ungauged basins in the region have relied heavily on calibration against a limited gauged streamflow database and somewhat subjective parameter regionalizations using areas of assumed hydrological similarity. The reliance of these approaches on limited historical records, often of dubious quality, introduces uncertainty in water resources decisions. Thus, it is necessary to develop methods of estimating model parameters that are less reliant on calibration. This thesis addresses the question of whether physical basin properties and the role they play in runoff generation processes can be used directly in the estimation of parameter values of the Pitman monthly rainfall-runoff model. A physically-based approach to estimating the soil moisture accounting and runoff parameters of a conceptual, monthly time-step rainfall-runoff model is proposed. The study investigates the physical meaning of the model parameters, establishes linkages between parameter values and basin physical properties and develops relationships and equations for estimating the parameters taking into account the spatial and temporal scales used in typical model applications. The estimationmethods are then tested in selected gauged basins in southern Africa and the results of model simulations evaluated against historical observed flows. The results of 71 basins chosen from the southern African region suggest that it is possible to directly estimate hydrologically relevant parameters for the Pitman model from physical basin attributes. For South Africa, the statistical and visual fit of the simulations using the revised parameters were at least as good as the current regional sets, albeit the parameter sets being different. In the other countries where no regionalized parameter sets currently exist, simulations were equally good. The availability, within the southern African region, of the appropriate physical basin data and the disparities in the spatial scales and the levels of detail of the data currently available were identified as potential sources of uncertainty. GIS and remote sensing technologies and a widespread use of this revised approach are expected to facilitate access to these data.
5
Luckemeier, Richard Ewald 1948. "A rainfall-runoff model for an urban watershed in Tucson, Arizona." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277165.
Повний текст джерелаАнотація:
The U.S. Geological Survey and the City of Tucson, Arizona, have been collecting rainfall and runoff data on several watersheds in the Tucson area for several years. Among the purposes of this project is to use the data to test rainfall-runoff models in an effort to find one to successfully simulate flood flows in Tucson. One such model, the Distributed Routing Rainfall-Runoff Model (DR3M), was tested using data collected on Rob Wash in Tucson. It was found DR3M performs about as well as it does in other parts of the United States, although it tends to underestimate flood flows for large storms and overestimate flows for smaller storms. Unique features with regard to the hydrology of urban Tucson require special attention when using DR3M; these features are associated with the nature of dry washes and summer rainfall in Tucson. Experience indicates DR3M is not truly a deterministic model.
6
Powell, Robert. "Industry value at risk in Australia." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2007. https://ro.ecu.edu.au/theses/297.
Повний текст джерелаАнотація:
Value at Risk (VaR) models have gained increasing momentum in recent years. Market VaR is an important issue for banks since its adoption as a primary risk metric in the Basel Accords and the requirement that it is calculated on a daily basis. Credit risk modelling has become increasingly important to banks since the advent of Basel 11 which allows banks with sophisticated modelling techniques to use internal models for the purpose of calculating capital requirements. A high level of credit risk is often the key reason behind banks failing or experiencing severe difficulty. Conditional Value at Risk (CVaR) measures extreme risk, and is gaining popularity with the recognition that high losses are often impacted by a small number of extreme events.
7
Koterba, Michael T. "Differential influences of storm and watershed characteristics on runoff from ephemeral streams in southeastern Arizona." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/191126.
Повний текст джерелаАнотація:
Relationships between thunderstorm and watershed variables and runoff from or within semiarid watersheds at Walnut Gulch, Arizona were examined. Variables showing greater sensitivity to basin and storm size were better flow predictors. Stepwise regression with three increasingly nonlinear algebraic models showed mean storm depth was the best simple predictor of runoff. Predictions improved using storm volume, a product of storm depth and areal extent. Initial runoff to streams was best described as a highly nonlinear function of storm and watershed variables. Runoff from a basin was a more linearized function of similar variables. The above differences were ascribed to channel transmission losses, reductions in runoff moving down initially dry channels. For a given basin and small storms, loss to runoff ratios exceeded 10:1 and were highly variable. Ratios were similar and less than 0.5:1 for storms centrally located over a basin and generating sufficient initial runoff to minimize flow variation due to losses. Losses increased disproportionately with basin size. Antecedent rainfall and first summer flows also affected rainfall runoff relationships in a differential manner. Wet conditions enhanced runoff more from larger versus smaller storms. First summer flows were less than expected probably because of higher soil infiltration and channel losses at the onset of summer storms. Overall, as storm size decreased or basin area increased, initial runoff was more often a localized phenomenon and downstream flow more dependent on storm depth, extent, location, and seasonal timing and basin channel losses, but less dependent on antecedent rainfall. Consequently, storm depth accounted for only 60% to 70% of the variation in flows while storm volume, antecedent rainfall, channel losses, and first summer flows explained 80% to 90%. Finally, oversimplifying storm or watershed variables or analytical methods led to errors in assessing their affect on runoff. It was also determined that current arguments supporting a recommendation to delete smaller, frequent annual floods to better fit remaining data to flood frequency curves were oversimplified. Distributed rainfall - runoff models with channel losses and regional storm depth - area - frequency data may be the way to develope flood curves for semiarid basins with short runoff records.
8
Kapangaziwiri, Evison. "Regional application of the Pitman monthly rainfall-runoff model in Southern Africa incorporating uncertainty." Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1006178.
Повний текст джерелаАнотація:
Climate change and a growing demand for freshwater resources due to population increases and socio-economic changes will make water a limiting factor (in terms of both quantity and quality) in development. The need for reliable quantitative estimates of water availability cannot be over-emphasised. However, there is frequently a paucity of the data required for this quantification as many basins, especially in the developing world, are inadequately equipped with monitoring networks. Existing networks are also shrinking due mainly to shortages in human and financial resources. Over the past few decades mathematical models have been used to bridge the data gap by generating datasets for use in management and policy making. In southern Africa, the Pitman monthly rainfall-runoff model has enjoyed relatively popular use as a water resources estimation tool. However, it is acknowledged that models are abstractions of reality and the data used to drive them is imperfect, making the model outputs uncertain. While there is acknowledgement of the limitations of modelled data in the southern African region among water practitioners, there has been little effort to explicitly quantify and account for this uncertainty in water resources estimation tools and explore how it affects the decision making process. Uncertainty manifests itself in three major areas of the modelling chain; the input data used to force the model, the parameter estimation process and the model structural errors. A previous study concluded that the parameter estimation process for the Pitman model contributed more to the global uncertainty of the model than other sources. While the literature abounds with uncertainty estimation techniques, many of these are dependent on observations and are therefore unlikely to be easily applicable to the southern African region where there is an acute shortage of such data. This study focuses on two aspects of making hydrologic predictions in ungauged basins. Firstly, the study advocates the development of an a priori parameter estimation process for the Pitman model and secondly, uses indices of hydrological functional behaviour to condition and reduce predictive uncertainty in both gauged and ungauged basins. In this approach all the basins are treated as ungauged, while the historical records in the gauged basins are used to develop regional indices of expected hydrological behaviour and assess the applicability of these methods. Incorporating uncertainty into the hydrologic estimation tools used in southern Africa entails rethinking the way the uncertain results can be used in further analysis and how they will be interpreted by stakeholders. An uncertainty framework is proposed. The framework is made up of a number of components related to the estimation of the prior distribution of the parameters, used to generate output ensembles which are then assessed and constrained using regionalised indices of basin behavioural responses. This is premised on such indices being based on the best available knowledge covering different regions. This framework is flexible enough to be used with any model structure to ensure consistent and comparable results. While the aim is to eventually apply the uncertainty framework in the southern African region, this study reports on the preliminary work on the development and testing of the framework components based on South African basins. This is necessitated by the variations in the availability and quality of the data across the region. Uncertainty in the parameter estimation process was incorporated by assuming uncertainty in the physical and hydro-meteorological data used to directly quantify the parameter. This uncertainty was represented by the range of variability of these basin characteristics and probability distribution functions were developed to account for this uncertainty and propagate it through the estimation process to generate posterior distributions for the parameters. The results show that the framework has a great deal of potential but can still be improved. In general, the estimated uncertain parameters managed to produce hydrologically realistic model outputs capturing the expected regimes across the different hydro-climatic and geo-physical gradients examined. The regional relationships for the three indices developed and tested in this study were in general agreement with existing knowledge and managed to successfully provide a multi-criteria conditioning of the model output ensembles. The feedback loop included in the framework enabled a systematic re-examination of the estimation procedures for both the parameters and the indices when inconsistencies in the results were identified. This improved results. However, there is need to carefully examine the issues and problems that may arise within other basins outside South Africa and develop guidelines for the use of the framework.iText 1.4.6 (by lowagie.com)
9
Price, Myra Ann. "Seasonal Variation in Runoff Curve Number." Thesis, The University of Arizona, 1998. http://hdl.handle.net/10150/225411.
Повний текст джерелаАнотація:
The seasonal variation in rainfall - runoff response is investigated for about 300 small watersheds throughout the United States. Data from USDA research watersheds were used to define runoff Curve Number for ordered data sets by months. Three major patterns of cyclic variation are found and investigated: 1) distinct and well - defined seasonal variations as typified by forested watersheds in heavy rainfall zones; 2) mildly cyclic variation found typically in meadows and grasslands, and 3) non - cyclic or unidentifiable patterns, including those with insufficient seasonal data. The only pattern that may be present is the well-defined seasonal variation found so far only in forested watersheds. Regional characteristics were found for individual crop types. For the watersheds studied there seemed to be no difference in the variation between crops except for meadow during the summer. Some associated background factors are explored, including long-term and short-term antecedent rainfall.
10
Bouraoui, Faycal. "Development of a continuous, physically-based distributed parameter, nonpoint source model." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-10192006-115604/.
Повний текст джерела
11
Mwelwa, Elenestina Mutekenya. "The application of the monthly time step Pitman rainfall-runoff model to the Kafue River basin of Zambia." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1006171.
Повний текст джерелаАнотація:
This thesis presents a discussion on the study undertaken in the application of the monthly time step Pitman rainfall-runoff model to the Kafue River basin. The study constituted one of the initial steps in the capacity building and expansion of the application of hydrologic models in the southern African region for water resources assessment, one of the core areas of the Southern African FRIEND project (Flow Regimes from International Experimental Network Data). The research process was undertaken in four major stages, each stage working towards achieving the research objectives. The first stage was the preparation of spatial data which included the selection and delineation of sub-catchments and inclusion of spatial features required to run the Pitman model and transferring the spatial data into SPATSIM. The second stage was the preparation of input data, mainly rainfall, streamflow, evaporation, and water abstraction data. This information was then imported into SPATSIM, which was able to assist in the further preparation of data by assessment of the input data quality, linking of observed flows and spatial interpolation of point rainfall data to average catchment rainfall in readiness for running and calibration of the model. The third stage was the running and calibration of the Pitman model. Use was made of both the automatic calibration facility, as well as manual calibration by means of the time series graph display and analysis facility of SPATSIM. Model calibration was used to obtain the best fit and an acceptable correlation between the simulated and the observed flows and to obtain simulation parameter sets for sub-catchments and regions within the Kafue catchment. The fourth stage was the analysis and evaluation of the model results. This included verification of results over different time periods and validation and testing of parameter transfers to other catchments. This stage also included the evaluation of SPATSIM as a tool for applying the model and as a database for the processing and storage of water resources data. The study’s output includes: A comprehensive database of hydrometeorological, physical catchment characteristics, landuse and water abstraction information for the Kafue basin; calibrated Pitman model parameters for the sub-catchments within the Kafue basin; recommendations for future work and data collection programmes for the application of the model. The study has also built capacity by facilitating training and exposure to rainfall-runoff models (specifically the Pitman model) and associated software, SPATSIM. In addition, the dissemination of the results of this study will serve as an effective way of raising awareness on the application of the Pitman model and the use of the SPATSIM software within Zambia and the region. The overall Pitman model results were found to be satisfactory and the calibrated model is able to reproduce the observed spatial and temporal variations in streamflow characteristics in the Kafue River basin.
12
Oogathoo, Shalini. "Runoff simulation in the Canagagigue Creek watershed using the MIKE SHE model." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101157.
Повний текст джерелаАнотація:
The Canagagigue Creek watershed, located in the Grand River Basin, is one of the fastest developing areas in Ontario. The watershed hydrology has changed considerably due to the increased anthropogenic activities, producing frequent floods and droughts as well as water quality problems. MIKE SHE, a watershed-scale model, was used to simulate surface runoff from the Canagagigue Creek watershed. Various management scenarios affecting the surface hydrology were also evaluated. The model was calibrated for four years (1994-95 to 1997-98) and validated for another four years (1990-91 to 19931-94). For the calibration period, the correlation between the observed and simulated daily runoff was satisfactory, as shown by the coefficient of determination value of 0.59. The coefficient of determination was 0.44 for the validation period. The Nash-Sutcliffe coefficients obtained were 59% and 40% for the calibration and validation period, respectively. Use of daily input data together with a simplistic snowmelt routine, was found to affect model performance during the winter/spring period. Henceforth, model performance can be greatly improved by adopting a more comprehensive method for simulating snowmelt and incorporating the frozen soil conditions. Overall, the model was able to simulate surface runoff reasonably well on annual, seasonal, monthly, and daily intervals, representing all the hydrological components adequately.With the various management scenarios simulated, it was found that the deforestation scenario considerably increased the total flow (11%). On the other hand, the high runoff peaks were decreased and low flows were increased considerably in the application of the tile drainage scenario. It was also observed that surface flow increased in wet years and decreased in normal and dry years in the climate change scenario. Though impacts of certain scenarios were almost negligible, their effects were significant when associated with the percentage area under transformation. Hence, it was concluded that the model can be used to simulate various management scenarios to solve hydrologic problems in the Southern Ontario climatic condition.
13
Sumner, Neil R. "Calibration of a conceptual rainfall-runoff model using simulated annealing." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 1995. https://ro.ecu.edu.au/theses/1169.
Повний текст джерелаАнотація:
Simulated annealing (Kirkpatrick et al, 1983) is used to estimate the parameters of a mathematical model that predicts the water yield from a catchment. The calibration problem involves finding the global minimum of a multivariate function that has many extraneous local minima, a situation in which conventional optimisation methods are ineffective. The objective function which quantifies discrepancies between the computed and observed streamflows must be carefully selected to satisfy the least square assumptions. Several published simulated annealing algorithms have been implemented, tested and evaluated using standard test functions. Appropriate cooling schedules are found for each algorithm and test function investigated. The number of function evaluations required to find the minimum is compared to published results for the test functions using either simulated annealing and other global optimisation methods. A new simulated annealing algorithm based on the Hooke and Jeeves (1961) pattern search method is developed and compared with existing algorithms from the literature.
14
Jaforullah, Mohammad. "Energy modelling in a general equilibrium framework with alternative production specifications." Title page, contents and astract only, 1988. http://web4.library.adelaide.edu.au/theses/09PH/09phj23.pdf.
Повний текст джерела
15
Michaud, Jene Diane. "Distributed rainfall-runoff modeling of thunderstorm-generated floods a case study in a mid-sized, semi-arid watershed in Arizona /." Diss., The University of Arizona, 1992. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1992_49_sip1_w.pdf&type=application/pdf.
Повний текст джерела
16
Fahy, Benjamin. "Evaluating the Impact and Distribution of Stormwater Green Infrastructure on Watershed Outflow." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4732.
Повний текст джерелаАнотація:
Green Stormwater Infrastructure (GSI) has become a popular method for flood mitigation as it can prevent runoff from entering streams during heavy precipitation. In this study, a recently developed neighborhood in Gresham, Oregon hosts a comparison of various GSI projects on runoff dynamics. The study site includes dispersed GSI (rain gardens, retention chambers, green streets) and centralized GSI (bioswales, detention ponds, detention pipes). For the 2017-2018 water year, hourly rainfall and observed discharge data is used to calibrate the EPA's Stormwater Management Model to simulate rainfall-runoff dynamics, achieving a Nash-Sutcliffe efficiency of 0.75 and Probability Bias statistic of 3.3%. A synthetic scenario analysis quantifies the impact of the study site GSI and compares dispersed and centralized arrangements. Each test was performed under four precipitation scenarios (of differing intensity and duration) for four metrics: runoff ratio, peak discharge, lag time, and flashiness. Design structure has significant impacts, reducing runoff ratio 10 to 20%, reducing peak discharge 26 to 68%, and reducing flashiness index 56 to 70%. There was a reverse impact on lag time, increasing it to 50 to 80%. Distributed GSI outperform centralized structures for all metrics, reducing runoff ratio 22 to 32%, reducing peak discharge 67 to 69%, increasing lag time 133 to 500%, and reducing flashiness index between 32 and 62%. This research serves as a basis for researchers and stormwater managers to understand potential impact of GSI on reducing runoff and downstream flooding in small urban watersheds with frequent rain.
17
Small, Aaron Brent. "A comparative evaluation of surface runoff models and methods on small developing watersheds in Northern Virginia." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-03302010-020635/.
Повний текст джерелаАнотація:
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993.18 color maps in back pocket. Vita. Abstract. Includes bibliographical references (leaves 137-139). Also available via the Internet.
18
Enright, Peter 1962. "Simulation of rainfall excess on flat rural watersheds in Quebec." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61952.
Повний текст джерела
19
Li, Yanqiu, and 李艳秋. "Monitoring, analyzing and modeling hydrological processes over a headwater catchment in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43085349.
Повний текст джерела
20
Wildegger-Gaissmaier, Anna Elisabeth. "Fluidized bed utilization of South Australian coals." Title page, contents and abstract only, 1988. http://web4.library.adelaide.edu.au/theses/09PH/09phw672.pdf.
Повний текст джерела
21
Gao, Zhanhai School of Mathematics UNSW. "Modelling Human Immunodeficiency Virus and Hepatitis C Virus Epidemics in Australia." Awarded by:University of New South Wales. School of Mathematics, 2001. http://handle.unsw.edu.au/1959.4/18187.
Повний текст джерелаАнотація:
This thesis is concerned with the mathematical modelling for human immunodeficiency virus (HIV) and hepatitis C virus (HCV) epidemics in Australia. There are two parts to this thesis. Part I is aimed at modelling the transmission of HIV and HCV via needle sharing among injecting drug users (IDUs). The dynamical model of an epidemic through needle sharing among IDUs is derived. This model reveals the correlation between needle sharing and the epidemic prevalence among IDUs. The simulations of HIV and HCV prevalence and incidence among IDUs in Australia are made with this model. The comparison of simulated results with literature estimates shows that the modelled results are consistent with the literature estimates. The effects of needle sharing and cleaning on HIV and HCV prevalence and incidence among IDUs in Australia are evaluated. Part II is devoted to modelling the spread of HIV in the general community in Australia. A mathematical model is formulated to assess the epidemiological consequences of injecting drug use and sexual transmission in Australia. The effects of highly active antiretroviral therapies (HAART) on the HIV epidemic are included. The modelled results are in broad agreement with the literature estimates and observed data. The long-term effects of HAART are also discussed.
22
Hearman, Amy. "A modelling study into the effects of rainfall variability and vegetation patterns on surface runoff for semi-arid landscapes." University of Western Australia. School of Earth and Geographical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0047.
Повний текст джерелаАнотація:
[Truncated abstract] Generally hydrologic and ecologic models operate on arbitrary time and space scales, selected by the model developer or user based on the availability of field data. In reality rainfall is highly variable not only annually, seasonally and monthly but also the intensities within a rainfall event and infiltration properties on semi-arid hillslopes can also be highly variable as a result of discontinuous vegetation cover that form mosaics of areas with vegetation and areas of bare soil. This thesis is directed at improving our understanding of the impacts of the temporal representation of rainfall and spatial heterogeneity on model predictions of hydrologic thresholds and surface runoff coefficients on semi-arid landscapes at the point and hillslope scales. We firstly quantified within storm rainfall variability across a climate gradient in Western Australia by parameterizing the bounded random cascade rainfall model with one minute rainfall from 15 locations across Western Australia. This study revealed that rainfall activity generated in the tropics had more within storm variability and a larger proportion of the storm events received the majority of rain in the first half of the event. Rainfall generated from fontal activity in the south was less variable and more evenly distributed throughout the event. Parameters from the rainfall analysis were then used as inputs into a conceptual point scale surface runoff model to investigate the sensitivity of point scale surface runoff thresholds to the resolution of rainfall inputs. This study related maximum infiltration capacities to average storm intensities (k*) and showed where model predictions of infiltration excess were most sensitive to rainfall resolution (ln k* = 0.4) and where using time averaged rainfall data can lead to an under prediction of infiltration excess and an over prediction of the amount of water entering the soil (ln k* > 2). For soils susceptible to both infiltration excess and saturation excess, total runoff sensitivity was scaled by relating drainage coefficients to average storm intensities (g*) and parameter ranges where predicted runoff was dominated by infiltration excess or saturation excess depending on the resolution of rainfall data were determined (ln g* <2). The sensitivity of surface runoff predictions and the influence of specific within storm properties were then analysed on the hillslope scale. '...' It was found that using the flow model we still get threshold behaviour in surface runoff. Where conditions produce slow surface runoff velocities, spatial heterogeneity and temporal heterogeneity influences hillslope surface runoff amounts. Where conditions create higher surface runoff velocities, the temporal structure of within storm intensities has a larger influence on runoff amounts than spatial heterogeneity. Our results show that a general understanding of the prevailing rainfall conditions and the soil's infiltration capacity can help in deciding whether high rainfall resolutions (below 1 h) are required for accurate surface runoff predictions. The results of this study can be considered a contribution to understanding the way within storm properties effect the processes on the hillslope under a range of overall storm, slope and infiltration conditions as well as an improved understanding of how different vegetation patterns function to trap runoff at different total vegetation covers and rainfall intensities.
23
Soucik, Victor. "Finding the true performance of Australian managed funds." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2002. https://ro.ecu.edu.au/theses/730.
Повний текст джерелаАнотація:
When making conclusions about the performance of managed funds, it is critical that the framework in which such performance is measured provides an accurate and unbiased environment. In this thesis I search for true performance of the two major classes of funds- equity as well as fixed interest managed funds. Focusing, first on the former class, I examine five measurement models across three risk-free proxies, nine benchmarks proposed by the extant literature (covering conditional and unconditional as well as single and multi factor definitions) and over three independent periods in an effort to identity (in a consistent setting) the most accurate and least biast methodology. I also use the Australian dataset, which inherently mitigates any data biases that may potentially afflict US studies of these methodologies, since these were developed from the same dataset on which they were later tested. Not finding a pre-existing benchmark that is objective yet informative, I develop an independent model that satisfies these, sourcing from fifteen factor candidates across four categories. I find that teaming up a fund based market factor with well-defined proxies for size, value, momentum and conditional dividend yield provides the optimal benchmark. The latter class comprising fixed-interest managed funds is a segment left largely unexplored in the financial literature and neglected outright in the Australian context. I examine three risk-free proxies, six benchmark classes encompassing twenty-one potential factors, across five models and two independent time frames in an effort to establish the most informative and least biased setting. The task is complicated by two issues - an acute lack of Australian data (demanding additional bootstrap simulations and bridging tests with the US markets) and the need for a two-pass (time-series and cross-sectional) analysis, arising from the different information content benchmarks carry in these two dimensions. My results, consistent across time, show that a correct combination of a bond market variable, a mixture of interest rate factors and economic factors as well as the proxy for movements in the equity markets yield the optimal benchmark. Both fund classes point to Jensen's Alpha as the preferred model, but Treynor and Mazuy's definition of a quadratic measure is adequate if timing-selectivity separation is required. Neither class is significantly sensitive to the choice of risk free proxy featuring in the performance measures.
24
Goodrich, David Charles. "Geometric simplification of a distributed rainfall-runoff model over a range of basin scales." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185051.
Повний текст джерелаАнотація:
Distributed rainfall-runoff models are gaining widespread acceptance; yet, a fundamental issue that must be addressed by all users of these models is definition of an acceptable level of watershed discretization (geometric model complexity). The level of geometric model complexity is a function of basin and climatic scales as well as the availability of input and verification data. Equilibrium discharge storage is employed to develop a quantitative methodology to define a level of geometric model complexity commensurate with a specified level of model performance. Equilibrium storage ratios are used to define the transition from overland to channel-dominated flow response. The methodology is tested on four subcatchments in the USDA-ARS Walnut Gulch Experimental Watershed in southeastern Arizona. The catchments cover a range of basins scales of over three orders of magnitude. This enabled a unique assessment of watershed response behavior as a function of basin scale. High quality, distributed, rainfall-runoff data were used to verify the model (KINEROSR). Excellent calibration and verification results provided confidence in subsequent model interpretations regarding watershed response behavior. An average elementary channel support area of roughly 15% of the total basin area is shown to provide a watershed discretization level that maintains model performance for basins ranging in size from 1.5 to 631 hectares. Detailed examination of infiltration, including the role and impacts of incorporating small-scale infiltration variability in a distribution sense, into KINEROSR, over a range of soils and climatic scales was also addressed. The impacts of infiltration and channel losses on runoff response increase with increasing watershed scale as the relative influence of storms is diminished in a semi-arid environment such as Walnut Gulch. In this semi-arid environment, characterized by ephemeral streams, watershed runoff response does not become more linear with increasing watershed scale but appears to become more nonlinear.
25
Dressler, Kevin Andrew. "Estimating the Spatial Distribution of Snow Water Equivalent and Simulated Snowmelt Runoff Modeling in Headwater Basins of the Semi-arid Southwest." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1063%5F1%5Fm.pdf&type=application/pdf.
Повний текст джерела
26
Dennis, Kevin. "A mathematical model to describe haemophilus influenzae type B within Western Australia." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 1995. https://ro.ecu.edu.au/theses/1160.
Повний текст джерелаАнотація:
This work is primarily aimed at determining the effect that an immunisation policy Is likely to have on the incidence of Haemophllus influenzae Type B (HIB) and systematic HIB in Western Australia. There was a significant effort made to collect data pertinent to the estimation of parameter values but since HIB has only been a notifiable disease since 1992, there was a distinct lack of relevant data available. Private communication with individual’s such as Dr Jeffrey Hanna and Dr Beryl Wild resulted in practical information being obtained that was used to estimate certain parameters. The deterministic mathematical models within the thesis are extensions of existing ideas tailored to suit the needs of this thesis. Chapter one is a basic introduction to the pursuit of modelling infectious diseases with a brief description of basic epidemiology concepts. It also shows that even simple models may not deliver analytical results. Chapter two extends a model used by Angela Mclean and allows some analytical results to be obtained by first simplifying the model and then solving using standard methods to give the equilibrium distributions for the proportions of people in each state within the model
27
Ernst, Wolfgang F. "The economic rationale for stochastic urban transport models and travel behaviour : a mathematical programming approach to quantitative analysis with Perth data." UWA Business School, 2003. http://theses.library.uwa.edu.au/adt-WU2005.0004.
Повний текст джерелаАнотація:
[Formulae and special characters can only be approximated here. Please see the pdf version of the abstract for an accurate reproduction.] This thesis reviews, extends and applies to urban traffic analysis the entropy concept of Shannon and Luce's mathematical psychology in a fairly complex and mathematically demanding model of human decision making, if it is solved as a deeply nested structure of logit calculus. Recognising consumers' different preferences and the universal propensity to seek the best choice when going to some desired goal (k), a transparent mathematical program (MP) is developed: the equivalent of a nested multinomial logit model without its inherent computational difficulty. The MP model makes a statistical assessment of individual decisions based on a randomised (measurable) utility within a given choice structure: some path through a diagram (Rk, Dk), designed a priori, of a finite number of sequential choices. The Equivalence Theorem (ET) formalises the process and states a non-linear MP with linear constraints that maximises collective satisfaction: utility plus weighted entropy, where the weight (1/θn) is a behavioural parameter to be calibrated in each case, eg for the Perth CBD. An optimisation subject to feasible routes through the (Rk, Dk) network thus captures the rational behaviour of consumers on their individually different best-choice decision paths towards their respective goals (k). This theory has been applied to urban traffic assignment before: a Stochastic User Equi-librium (SUE). What sets this thesis apart is its focus on MP models that can be solved with standard Operations Research software (eg MINOS), models for which the ET is a conditio sine qua non. A brief list of SUE examples in the literature includes Fisk's logit SUE model in (impractically many) route flows. Dial's STOCH algorithm obviates path enumeration, yet is a logit multi-path assignment procedure, not an MP model; it is nei-ther destination oriented nor an optimisation towards a SUE. A revision of Dial's method is provided, named STOCH[k], that computes primal variables (node and link flows) and Lagrangian duals (the satisfaction difference n→k). Sheffi & Powell presented an unconstrained optimisation problem, but favoured a probit SUE, defying closed formulae and standard OR software. Their model corresponds to the (constrained) dual model here, yet the specifics of our primary MP model and its dual are possible only if one restricts himself to logit SUE models, including the ET, which is logit-specific. A real world application needs decomposition, and the Perth CBD example is iteratively solved by Partial Linearisation, switching from (measured) disutility minimisation to Sheffi & Powell's Method of Successive Averages near the optimum. The methodology is demonstrated on the Perth Central Business District (CBD). To that end, parameter Θ is calibrated on Main Roads' traffic count data over the years 1997/98 and 1998/99. The method is a revision of Liu & Fricker's simultaneous estimation of not only Θ but an appropriate trip matrix also. Our method handles the more difficult variable costs (congestion), incomplete data (missing observations) and observation errors (wrong data). Finally, again based on Main Roads' data (a sub-area trip matrix), a Perth CBD traffic assignment is computed, (a) as a logit SUE and - for comparison - (b) as a DUE (using the PARTAN method of Florian, Guélat and Spiess). The results are only superficially similar. In conclusion, the methodology has the potential to replace current DUE models and to deepen transport policy analysis, taking into account individual behaviour and a money-metric utility that quantifies 'social benefits', for instance in a cost-benefit-analysis.
28
Lee, Haksu. "Development and performance analysis of a physically based hydrological model incorporating the effects of subgrid heterogeneity." University of Western Australia. School of Environmental Systems Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0129.
Повний текст джерелаАнотація:
[Truncated abstract] The balance equations of mass and momentum, defined at the scale of what has been defined as a Representative Elementary Watershed (REW) has been proposed by Reggiani et al. (1998, 1999). While it has been acknowledged that the REW approach and the associated balance equations can be the basis for the development of a new generation of distributed physically based hydrological models, four building blocks have been identified as necessary to transform the REW approach into, at the very least least, a workable modelling framework beyond the theoretical achievements. These are: 1) the development of reasonable closure relations for the mass exchange fluxes within and between various REW sub-regions that effectively parameterize the effects of sub-REW heterogeneity of climatic and landscape properties, 2) the design of numerical algorithms capable of generating numerical solutions of the REW-scale balance equations composed of a set of coupled ordinary differential and algebraic equations for the number of REWs constituting a study catchment and the sub-regions within the REWs, 3) applications of the resulting numerical model to real catchments to assess its performance in the prediction of any specified hydrological variables, and 4) the assessment of the model reliability through estimation of model predictive uncertainty and parameter uncertainty. This thesis is aimed at making substantial progress in developing each of these building blocks. Chapter 1 presents the background and motivation for the thesis, while Chapter 2 summarizes its main contributions. Chapter 3 presents a description of the closure problem that the REW approach faces, and presents and implements various approaches to develop closure relations needed for the completeness of balance equations of the REW approach. ... In addition, Chapter 4 also shows an initial application of CREW to a small catchment, Susannah Brook in the south-west of Western Australia. Chapter 5 presents the application of CREW to two meso-scale catchments in Australia, namely Collie and Howard Springs, located in contrasting climates. Chapter 6 presents results of the estimation of predictive uncertainty and parameter sensitivity through the application of CREW to two catchments in Australia, namely Susannah Brook and Howard Springs, by using the Generalized Likelihood Uncertainty Estimation (GLUE) methodology. Finally, Chapter 7 presents recommendations for future work for the further advancement of the REW approach. Through these exercises this PhD thesis has successfully transformed the REW-scale coupled balance equations derived by Reggiani et al. (1998, 1999) into a new, well tested numerical model blueprint for the development and implementation of distributed, physically based models applicable at the catchment, or REW scale.
29
O???Brien, Peter Banking & Finance Australian School of Business UNSW. "Term structure modelling and the dynamics of Australian interest rates." Awarded by:University of New South Wales. School of Banking and Finance, 2006. http://handle.unsw.edu.au/1959.4/28283.
Повний текст джерелаАнотація:
This thesis consists of two related parts. In the first part we conduct an empirical examination of the dynamics of Australian interest rates of six different maturities, covering the whole yield curve. This direct study of the long rates is quite novel. We use maximum likelihood estimation on a variety of models and find some results that are in stark contrast to previous studies. We estimate Poisson-jump diffusion (PJD) models and find very strong evidence for the existence of jumps in all daily interest rate series. We find that the PJD model fits short-rate data significantly better than a Bernoulli-jump diffusion model. We also estimate the CKLS model for our data and find that the only model not rejected for all six maturities is the CEV model in stark contrast to previous findings. Also, we find that the elasticity of variance estimate in the CKLS model is much higher for the short-rates than for the longer rates where the estimate is only about 0.25, indicating that different dynamics seem to be at work for different maturities. We also found that adding jumps to the simple diffusion model gives a larger improvement than comes from going from the simple diffusion to the CKLS model. In the second part of the thesis we examine the Flesaker and Hughston (FH) term structure model. We derive the dynamics of the short rate under both the original measure and the risk-neutral measure, and show that some criticisms of the bounds for the short rate may not be significant in actual applications. We also derive the dynamics of bond prices in the FH model and compare them to the HJM model. We also extend the FH model by allowing the martingale to follow a jump-diffusion process, rather than just a diffusion process. We derive the unique change of measure that guarantees the family of bond prices is arbitrage-free. We derive prices for caps and swaptions, and extend the results to include Bermudan swaptions and show how to price options with the jump-diffusion version of the FH model.
30
Huth, Anne M. Kramer. "Geochemical and isotopic mixing models : two case studies in a snow-dominated and semi-arid environment." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/191260.
Повний текст джерелаАнотація:
The influence of climate and antecedent moisture conditions on hydrological and biogeochemical fluxes was studied and contrasted in three nested, high-elevation, snowmelt-dominated catchments in the Sierra Nevada, California and one basin-floor, semi-arid catchment in southeastern Arizona. Investigations were completed within a different two-year period at each site, with the second year being climatically different (typically drier) than the first. Spring snowmelt, widespread winter frontal precipitation, and episodic summer rains induce surface water flow in these catchments, though the timing and magnitude of nutrient redistribution among soil and stream compartments varies in each. Surface water flow from spring snowmelt in high-elevation catchments travels through the subsurface or across the surface as direct runoff A more typical process producing surface water flow in semi-arid catchments is flooding during episodic or widespread rainfall. Hydrograph separations at Emerald Lake, Topaz Lake and Marble Fork catchments in Sequoia National Park, California, revealed that the majority of snowmelt flowed through soil before entering the stream in both average and highsnow years. The Emerald Lake watershed had a higher fraction of old water in its outflow in the average accumulation year because of the previous year's high accumulation and longer melt season. A mixing model analysis performed of the upper San Pedro River, Arizona, for wet and dry years showed that summer flood hydrographs were composed mainly of precipitation and surface runoff in both years, though a higher soil-water input occurred in the wetter year and in early season floods in the dry year. Stream and soil water nitrate concentrations were higher during floods in the dry year. Early season floods in the dry year exhibited more variability in stream water nitrate and sulfate, whereas late season flood concentrations reflected a well-mixed system and therefore less variation of these species during flood hydrographs. These data showed that periods of below average precipitation preceding major runoff periods result both in less soil water and solute export during summer floods in basin-floor catchments and less direct snowmelt in high-elevation catchments. Hydrologic and solute export in each catchment, despite their differing geographical locations, responds in similar ways to climate variability.
31
Carter, Robert C. (Robert Charles) 1950. "The macro economic evaluation model (MEEM) : an approach to priority setting in the health sector." Monash University, Dept. of Management, 2001. http://arrow.monash.edu.au/hdl/1959.1/8672.
Повний текст джерела
32
Fonley, Morgan Rae. "Effects of oscillatory forcing on hydrologic systems under extreme conditions: a mathematical modeling approach." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/2075.
Повний текст джерелаАнотація:
At the large watershed scale, we emphasize the effects of flow through a river network on streamflow under dry conditions. An immediate consequence of assuming dry conditions is that evapotranspiration causes flow in the river network to exhibit oscillations. When all links in the river network combine their flow patterns, the oscillations interact in ways that change the timing and amplitude of the streamflow waves at the watershed outlet. The geometric shape of the river network is particularly important, so we develop an analytic solution for streamflow which emphasizes that importance.
Doing hydrology backward is a strategy recently developed by several researchers to deal with uncertainty in measurements of forcing terms applied to hydrologic models. The strategy has also been applied to resolve the assumption of homogeneity on realistic catchments that exhibit many heterogeneous properties. In this work, we demonstrate hydrology in the backward direction applied to two examples: using streamflow at the catchment scale to determine runoff at the hillslope scale and using the hillslope runoff to infer the applied evapotranspiration forcing under the assumption of dry conditions. In order to work across scales, we utilize the analytic solution for streamflow at the outlet of a river network. At the hillslope scale, we develop a soil model to create fluxes consistent with observed soil processes.
33
Kirkpatrick, Raelene. "A mathematical analysis of the financial and medical impact of hepatitis C among drug users in Perth, Western Australia." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2003. https://ro.ecu.edu.au/theses/1332.
Повний текст джерелаАнотація:
The ability of public health planners continues to be hampered by uncertainties encountered with transmissible diseases. Key epidemiological factors such as, how many Western Australian injecting drug users are hepatitis C seropositive or will become infected, duration of intravenous drug use, the intensity of infection, the fraction of those infected that will develop end-stage disease and after how long a period, all combine to limit the ability of a mathematical model to predict future trends. These models can, however, provide information about certain epidemiological parameters and identify data required to predict future trends. They can be applied to make predictions about the course of infection in the individual and provide a guide to the interpretation of the observed data. This research aims to develop a model of the transmission and spread of hepatitis C, adapting existing models used to predict the spread of HIV and AIDS in one and two sex communities. This model will be used to demonstrate the dynamics and incidence of hepatitis C infection among injecting drug users in Perth, Western Australia. Predictions derived from the model will then be used to undertake an analysis of the cost of treating those with hepatitis C and cirrhosis related complications, resulting in a prediction of the financial impact of hepatitis C on the Western Australian community.
34
Odeh, Inakwu Ominyi Akots. "Soil pattern recognition in a South Australian subcatchment /." Title page, contents and abstract only, 1990. http://web4.library.adelaide.edu.au/theses/09PH/09pho23.pdf.
Повний текст джерела
35
Kwok, Ho King Calvin Actuarial Studies Australian School of Business UNSW. "Energy price modelling and risk management." Awarded by:University of New South Wales. Actuarial Studies, 2007. http://handle.unsw.edu.au/1959.4/40602.
Повний текст джерелаАнотація:
This thesis focuses on the development of a forecasting model for short- to medium-term electricity spot prices, based on modelling the dynamics of the supply and demand functions. It is found that the equilibrium assumption frequently adopted in electricity price models does not always hold; to overcome this problem, a notional demand process derived from the market clearing condition is proposed. Not only is this demand process able to capture all the price-affecting factors in one variable, but it also allows the equilibrium assumption to be satisfied and a spot price model to be built, using any appropriate form of hypothetical supply function. In addition, this thesis presents a model for approximating and modelling the bid stacks by capturing the points that govern their shape and location. Integrating these two models provides a realistic model that has a mean absolute percentage error of approximately 19% and 24% for week- and month-ahead forecasts respectively, when applied to the New South Wales (NSW) half-hourly electricity spot prices. Additionally, the density forecasting evaluation method proposed by Diebold et al. (1998) is employed in the thesis to assess the performance of the model. Besides the development of a spot price model, a two-part empirical study is made of the prices of NSW electricity futures contracts. The first part of the study develops a method based on the principle of certainty equivalence, which enables the market utility function to be recovered from a set of futures market quotes. The method is tested with two different sets of simulated data and works as expected. However, it is unable to obtain useful results from the NSW market quotes due to the poor data quality. The second part uses a regression method to investigate the relationship between futures prices and the descriptive statistics of the underlying spot prices. The result suggests that futures prices in NSW are linear combinations of the median and volatility of the final payoff.
36
Thein, Hla-Hla Public Health & Community Medicine Faculty of Medicine UNSW. "Measuring the health burden of hepatitis C at an individual and population level in Australia." Awarded by:University of New South Wales. School of Public Health and Community Medicine, 2006. http://handle.unsw.edu.au/1959.4/24967.
Повний текст джерелаАнотація:
This thesis examines the effect of hepatitis C virus infection (HCV) on health-related quality of life (HRQOL) to define burden of disease at individual and population levels. A systematic review of HCV HRQOL studies was undertaken with translation of Short Form-36 (SF-36) Health Survey data into community-weighted health state utilities using three different methods. Derived estimates of health utilities were 0.87 for HCV treatment-induced sustained virological response (SVR); 0.81 for pre-cirrhosis; 0.76 for compensated cirrhosis; 0.69 for decompensated cirrhosis; 0.67 for hepatocellular carcinoma (HCC); and 0.77 for liver transplant. The HCV health state utilities varied considerably from expert estimates, with relatively lower estimates for early liver disease and higher estimates for advanced liver disease, but were comparable to direct patient-elicited utilities. A study utilising data from population-based health surveys incorporating HCV screening among prisoners at Australian correctional centres in 1996 and 2001 showed no measurable effect of HCV on HRQOL, including that attributable to HCV viraemia. Compared to uninfected Australian norms, prisoners had lower HRQOL irrespective of HCV status. Several non-HCV factors such as age, co-morbidity, severity of depressive symptoms, and medical care utilization influenced HRQOL. A prospective study of health outcomes among HCV monoinfected and HIV/HCV coinfected individuals conducted at Sydney tertiary level hepatitis clinics between 2003 and 2005 found similar cognitive function, mood, and HRQOL patterns in these two HCV groups in the context of pegylated interferon (PEG-IFN) alfa-2a and ribavirin therapy. The HCV groups had similar levels of pre-treatment HRQOL impairment, further on-treatment deterioration, and posttreatment improvements. SVR was associated with significant HRQOL improvements, but mental HRQOL improvement was also seen in individuals not achieving an SVR. The impact of HCV treatment uptake on HCV-related burden of disease at a population level in Australia was examined using a mathematical model. The model estimated that in 2004, there were ~181,500 cases of chronic HCV infection, 7,020 with HCV-related cirrhosis, and annual incidence of 238 cases of HCV-related liver failure and 70 cases of HCV-related HCC. Compared to no treatment, current treatment levels (~1% of HCV-infected individuals per annum) would reduce projected HCV-related cirrhosis and advanced liver disease numbers by ~30% at 2020 and a gain of ~122,200 Quality-Adjusted Life Years (QALYs). Even with a five-fold increase from current treatment levels, advanced liver disease numbers will continue to increase through 2020 but will be reduced by ~55% and a gain of ~483,200 QALYs.
37
Pokhrel, Pranav. "The Study of Temporal and Spatial Variability of Degree Day Factor of Snowmelt in Colorado." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849730/.
Повний текст джерелаАнотація:
Snowmelt is one of the major sources of surface water supply and ground-water recharge in high elevation areas and can also cause flooding in snow dominated watersheds. Direct estimation of daily snowmelt requires daily snow water equivalent (SWE) measurements that are not always available, especially in places without monitoring stations. There are two alternative approaches to modeling snowmelt without using direct measurements of SWE, temperature-based and energy-based models. Due to its simplicity, computational efficiency, and less input data requirement, the temperature-based method is commonly used than the energy-based method. In the temperature-index approach snowmelt is estimated as a linear function of average air temperature, and the slope of the linear function is called the degree-day factor (DDF). Hence, the DDF is an essential parameter for utilizing the temperature-based method to estimate snowmelt. Thereby, to analyze the spatial properties of DDF, 10 years DDF from the entire state of Colorado was calculated for this research. Likewise, to study the temporal properties, DDFs for 27 years from the White Yampa water basin and the Colorado Headwaters water basin were calculated.
As a part of the spatial analysis, the calculated DDFs were correlated with spatial variables (slope, aspect, latitude and elevation) and a spatial correlation graph was created to observe the possibility of predicting DDF. Also a multivariate regression model was prepared using these spatial variables to predict the DDF using spatial variables. Further, the DDFs calculated from Colorado headwaters and the White Yampa water basins were correlated for annual temporal variation, daily variation, variation with peak snow water equivalent and variation with important temporal cycles like accumulation period and melting period of snowmelt. The result obtained from this study showed that the variability of DDF is more dependent upon temporal factors compared to the spatial factors. Also, the results showed that predicting DDF is a difficult process and requires complex methods than simple linear models or multivariate models.
38
Stovold, Matthew R. "Modeling urban stormwater disposal systems for their future management and design." University of Western Australia. School of Environmental Systems Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0111.
Повний текст джерелаАнотація:
[Truncated abstract]This thesis investigates aspects of urban stormwater modeling and uses a small urban catchment (NE38) located in the suburb of Nedlands in Perth, Western Australia to do so. The MUSIC (Model for Urban Stormwater Improvement Conceptualisation) model was used to calibrate catchment NE38 using measured stormwater flows and rainfall data from within the catchment. MUSIC is a conceptual model designed to model stormwater flows within urban environments and uses a rainfall-runoff model adapted to generate results at six minute time steps. Various catchment scenarios, including the use of porous asphalt as an alternative road surface, were applied to the calibrated model to identify effective working stormwater disposal systems that differ from the current system. Calibrating catchment NE38 using the MUSIC model was attempted and this involved matching modeled stormwater flows to stormwater flows measured at the catchment drainage point. This was achieved by measuring runoff contributing areas (roads) together with rainfall data measured from within the catchment and altering the seepage constant parameter for all roadside infiltration sumps. ... The MUSIC model generated future scenario outcomes for alternative stormwater disposal systems that displayed similar or improved levels of performance with respect to the current system. The following scenarios listed in increasing order of effectiveness outline future stormwater disposal systems that may be considered in future urban design. 1. 35% porous asphalt application with no sumps in 2036 2. 35% porous asphalt application with no sumps in 2064 3. 68% porous asphalt application with no sumps in 2036 4. 68% porous asphalt application with no sumps in 2064. Future scenarios using the current stormwater disposal system (with roadside infiltration sumps) with porous asphalt were also run. These scenarios reduced stormwater runoff and contaminant loading on the catchment drainage point however the inclusion of a roadside infiltration sump system may not appeal to urban designers due to the costs involved with this scenario. Climate change will affect the design of future stormwater disposal systems and thus, the design of these systems must consider a rainfall reducing future. Based on the findings of this thesis, current stormwater runoff volumes entering catchment drainage points can be reduced together with contaminant loads in urban environments that incorporate porous asphalt with a stormwater disposal design system that is exclusive of roadside infiltration sumps.
39
Fiorentino, Francesca. "Mathematical models of the impact of rabbit calicivirus disease (RCD) on the European rabbit, Oryctolagus cuniculus, in Australia." Thesis, University College London (University of London), 2004. http://discovery.ucl.ac.uk/1446810/.
Повний текст джерелаАнотація:
This thesis relates to the work of building a mathematical model of the impact of Rabbit Calicivirus Disease (RCD) on the European Rabbit, Oryctolagus cuniculus, in Australia. After introducing the general biology of rabbits and the immunology of RCD, we build a time-dependent single site model. We construct a single-site population dynamic model with age structure, seasonal birth rate, density dependent regulation of the population size and climatic variability for various regions of Australia. After investigating suitable parameter ranges, we incorporate the disease dynamics through an indirect transmission model based on two different hypotheses which we call the Strong Juvenile hypothesis and the Weak Juvenile hypothesis. These differ in their assumption about Juvenile immunity to the disease. The ecological impact of both hypotheses is tested for both the single site and multiple site (spatial) models. The disease impact is investigated by varying the disease virulence, i.e. a parameter measuring the "strength" of the virus. Subsequently, a multiple site (spatial) model for the Riverina region is built by using the single-site model as building block. Data from Lake Urana is used to parameterize a seasonal emigration rate from each site. Density dependent immigration is added together with a hazard coefficient which rabbits face when leaving one site and trying to become established in another. Acceptance in a new site is regulated by the population density at the entry site. Several spatial configurations of sites are tested and the spatial dynamics of the disease is investigated. Finally, we construct a model to investigate the long term evolution of the disease virus. We postulate the existence of several strains of the disease and trade-offs between disease characteristics. We allow for mutation of the virus and run the model for two contrasting geographical regions of Australia. We compare the results for the different regions and the different hypotheses regarding Juvenile immunity (the Strong Juvenile hypothesis and the Weak Juvenile hypothesis). It is shown, unexpectedly, that intermediate levels of disease virulence are not selected.
40
Farag, Saarah A. "A comparison of advanced time series models for environmental dependent stock recruitment of the western rock lobster." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 1998. https://ro.ecu.edu.au/theses/997.
Повний текст джерелаАнотація:
Time series models have been applied in many areas including economics, stuck recruitment and the environment. Most environmental time series involve highly correlated dependent variables, which makes it difficult to apply conventional regression analysis, Traditionally, regression analysis has been applied to the environmental dependent stock and recruitment relationships for crustacean species in Western Australian fisheries. Alternative models, such as transfer function models and state space models have the potential to provide unproved forecasts for these types of data sets. This dissertation will explore the application of regression models, transfer function models, and state space models to modelling the puerulus stage of the western rock lobster (Panulirus Cynus) in the fisheries of Western Australia. The transfer function models are consulted to examining the influences of the environment on crustacean species and can be used where correlated variables are involved. These models aim at producing short-term forecasts that may help in the management of the fisheries. In comparison with regression models, TFM models gave better forecast values with state space models given the forecast values in the first two years. Overall, it was shown that environmental effects, westerly winds and the Leeuwin Current, have a significant effect on the puerulus settlement for Dongara and Alkimos. It was also shown that westerly winds and spawning stock have a significant effect on the puerulus settlement at the Abrolhos Islands.
41
Rigby, Elaine Rose. "Modelling results of student evaluations to improve the quality of teaching in accounting departments." Thesis, Canberra, ACT : The Australian National University, 1995. http://hdl.handle.net/1885/133664.
Повний текст джерелаАнотація:
The Course Evaluation Questionnaire is a student evaluation instrument designed to
measure the teaching performance of academic organisational units. The statistical
qualities of its scales, as well as their sensitivity, reliability and validity have been
confirmed in other studies. This study situates the development of the CEQ within the
context of public sector reform in Australia, which emphasised accountability measured
through performance indicators. It reviews previous research using the CEQ and
attempts to apply the CEQ in a new way, by using responses from students who were
enrolled in a first year accounting subject at three established universities, to construct a
model which quantifies the relationship between students' overall satisfaction score and
certain variables which were tested for their contribution to students' satisfaction. The
variables which were found to make a statistically significant contribution to student
satisfaction were: good teaching; clear goals and standards; appropriate workload;
emphasis on student independence; gender; language background; and university. The
major conclusions reached are 1) that of the five CEQ scales good teaching appears to be
most strongly related to overall satisfaction and that positive effect is the same at all three
universities, 2) that gender affects satisfaction at all three universities and 3) that
language background has an effect at two universities. The implications of these findings
for quality teaching in accounting courses and for accounting education research are
discussed.
42
Choi, Yoon-Hong. "The mathematical modelling of the Ross River Virus transmission." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 1997. https://ro.ecu.edu.au/theses/896.
Повний текст джерелаАнотація:
Ross River virus is one of the most severe communicable diseases in Australia. During the 1995/96 outbreak of Ross River virus in south-western Australia, over 1 ,300 human cases were reported. Since the symptoms of the disease are sometimes too weak to be diagnosed, it is important to determine the number of humans who actually contracted the virus during outbreaks. To do this, several mathematical models with different hypotheses are constructed and analysed mathematically. The threshold mathematical conditions of these models suggest that as well as the size of the vector mosquito population, the population size and length of viraemia periods; of host populations and the infection rates between the hosts and vectors play the main roles in the transmission. Several parameters in the transmission are currently unknown, so only simple models of RRV transmission are computer-simulated. Some of the unknown parameters are extrapolated from published studies of other arboviruses. The sensitivities of the models to some of the unknown parameters are also examined. Simulation results indicate the sero-conversion rates and ratios of clinical to subclinical human infections during the outbreaks which occurred in the Peel and Leschenault districts in Southwestern Australia.
43
Galarraga, Sanchez Remigio Hernan. "Scale effects in determining snowmelt from mountainous basins using a distributed approach for snow water equivalence and radiation, and a point snowmelt model." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/191186.
Повний текст джерелаАнотація:
Rates of snowmelt distributed across Emerald Lake watershed, an alpine basin located in the Sierra Nevada, California, were estimated for water year 1987 using a point snowmelt model applied to regions that were classified based on distributed snow water equivalence and net solar radiation (NSR). A 5-m resolution digital elevation model (DEM) and a 5-m classified digital terrain model of snow water equivalence (SWE) were resampled to coarser resolutions (25-m, 30-m, 50-m, and 100-m) using the nearest neighbor approach. These images were used to define other snowmelt physical parameters and the initial state of the snowpack before melting. Topographic parameters calculated at 50-m and 100-m resolution exhibited significant differences in their histogram distribution as compared to the 5-m DEM. The most important were variations in slope, aspect, sky view factor, and terrain configuration factor, which influenced radiation calculations and the definition of distributed parameters for snowmelt calculations. Elevations, however, did not change significantly from one resolution to the other. The distribution of topographic parameters modeled at 25-m and 30-m, remained almost unchanged. Four, seven and ten classes of snow water equivalence and net solar radiation were combined using a band interleave process to determine the maximum number of combined classes. The point snowmelt model was then applied to these areas, which shared similar SWE and NSR characteristics, to obtain hourly melt rates. Modeled snowmelt rates were compared to the total daily discharge observed at the outlet of Emerald Lake watershed. There was good agreement for resolutions S-, 25-, 30-, and 50-m but not for the 100-m OEM, as modeled net solar radiation was too high and water was released from the basin too early. Model performance using three tests (Nash-Sutcliffe criteria, sum of squares of the deviations and the sum of the absolute differences between observed discharge and computed melting) showed that the 30-m resolution OEM with combined classes of 7 SWE and 7 NSR provided the best snowmelt performance for this distributed approach. Finally, fractional snow cover area at one month intervals were estimated, showing that this approach offers the potential to model spatially distributed snow covered area in alpine regions.
44
Bandeen, Reid Francis 1957. "Simulations of dry well recharge in the Tucson Basin, Arizona." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276654.
Повний текст джерелаАнотація:
The variably saturated flow model Unsat 2 was used for three case study simulations of dry well recharge in the Tucson Basin, Arizona. Dry well design, and rainfall/runoff and vadose zone conditions representative of the locality were assumed in the simulations to address travel time to the regional aquifer, rates and extent of radial flow, and relative degree of solute attenuation by sorption and dilution with regional groundwater. Soil specific surface was used to estimate relative degree of sorption among the three cases. One case of uniform soil composition and two cases of layered soil composition were simulated. Clay content had the greatest influence on specific surface. Hydraulic conductivity had the greatest influence on soil water velocities and degree of radial flow. The presence of layered subsurface conditions that included strata of low hydraulic conductivity enhanced the degree of subsurface solute attenuation by sorption and dilution.
45
Steele, Madeline Olena. "Effects of HRU Size on PRMS Performance in 30 Western U.S. Basins." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/654.
Повний текст джерелаАнотація:
Semi-distributed hydrological models are often used for streamflow forecasting, hydrological climate change impact assessments, and other applications. In such models, basins are broken up into hydrologic response units (HRUs), which are assumed to have a relatively homogenous response to precipitation. HRUs are delineated in a variety of ways, and the procedure used may impact model performance. HRU delineation procedures have been researched, but it is still not clear how important these subdivision schemes are or which delineation methods are most effective. To start addressing this knowledge gap, this project investigated whether or not HRU size has a significant effect on streamflow simulation at the mouth of a watershed. To test this, 30 gaged, relatively unimpaired western U.S. basins were each modeled with 6 HRU sets of different sizes using the Precipitation Runoff Modeling System (PRMS). To isolate size as a variable, HRUs were delineated using stream catchments. For each basin, streams were defined with 6 different threshold levels, producing HRUs of differing sizes. Nineteen model parameters were derived for each HRU using nationally consistent GIS datasets, and all other model parameters were left at default values. Climate inputs were derived from a national 4-km2 gridded daily climate dataset. After calibration, 4 goodness-of-fit metrics were calculated for daily streamflow for each HRU set. Uncalibrated model performance was generally poor for a variety of reasons, but comparison of the models was still informative. Results for the 30 basins across the 6 HRU size classes showed that HRU size did not significantly impact model performance across all basins. However, in basins that had less total precipitation and higher elevation, sensitivity of model performance to HRU subdivision levels was slightly greater, though not significantly so. Findings indicate that, in most basins, little subdivision may be required for good model performance, allowing for desirable simplicity and fewer degrees of freedom without sacrificing runoff simulation accuracy.
46
Cobiac, Linda J. "Sedimentation ponds and their operation in stormwater systems." Thesis, 2001. http://hdl.handle.net/2440/115878.
Повний текст джерелаАнотація:
The efficacy of sedimentation ponds as a means of sediment and heavy metal remediation is investigated, with particular regard to the physical and chemical conditions that may lead to remobilisation of metals from the sedimentsThesis (M.Eng.Sc.) -- University of Adelaide, Dept. of Civil and Environmental Engineering, 2001
47
Shin, Mun-Ju. "Pragmatic methods for analysing performance and identifiability issues in rainfall-runoff modelling." Phd thesis, 2014. http://hdl.handle.net/1885/156363.
Повний текст джерелаАнотація:
Uncertainty has become a primary issue for modellers and decision makers concerned about understanding the behaviour of natural systems. Characterising uncertainty is an important modelling step for assessing the options for managing it. Without an understanding of a model's strength and weakness and of model uncertainty we cannot judge if management interventions will cause significant change. Methods for characterising uncertainty range from empirical, through naive Monte Carlo to formal Bayesian methods. Most uncertainty methods are complex and difficult to implement. But uncertainty analysis can be so much simpler than this and lead to powerful insights and model improvements. This is illustrated in this thesis where it demonstrates that simple methods can provide useful insight into model uncertainty. This thesis uses four hydrological models of varying complexity applied to five catchments of differing characteristics. It shows that uncertainty analysis can be simple and provide crucial insights into the behaviour of environmental models. This thesis begins by showing how a simple global sensitivity analysis can identify parameters in a model that are unimportant in explaining model outputs, and that might improve identifiability either by checking which ones can be fixed or by changing the objective function. The results confirm that for the catchment examined a minimum of five years is required to characterise the sensitivities assuredly and that only the simpler models have well-identified parameters, but parameter sensitivities vary between catchments. The simple global sensitivity analysis is then complemented with an identifiability analysis of the four models. More complex models have more uncertain and poorly-identified parameters. Model structure is shown to be the major problem in obtaining a global solution, far outweighing data informativeness and the objective function selected. Moreover, the more complex models do not dominate the performance of the less complex, the best model depending on the catchment of interest and even the calibration period. This thesis then considers the issue of minimum acceptable model performance. It is argued that a typical hydrological model identification process of optimising the objective function and reporting the performance in a validation period is no longer sufficient practice. If models with lower objective function values are to be accepted, we need to know how bad a model will be considered as good enough. It proposes a generic approach that uses elimination of Pareto-dominated models and cross-validation to identify minimal criteria for which models should be accepted. Finally, this thesis investigated uncertainties introduced by variable time delays between rainfall events and hydrograph response, a response complexity not handled well by rainfall-runoff models. Smaller events tend to have larger time delays and variability compared to larger events. It proposes a simple solution for model calibration by shifting rainfall and/or modelled times series in events by the amount of observed time lag, as calculated by a cross-correlation function. A variable integer time delay method leads to general improvements in simulation on independent periods, when invoking performance metrics of a Shifted Nash-Sutcliffe Efficiency and absolute relative bias. Overall the variable integer time delay method also improved parameter identifiability.
48
Post, David Andrew. "Identification of relationships between catchment-scale hydrologic response and landscape attributes." Phd thesis, 1996. http://hdl.handle.net/1885/144311.
Повний текст джерела
49
Jeong, Jaehak 1974. "A hydrodynamic diffusion wave model for stormwater runoff on highway surfaces at superelevation transitions." Thesis, 2008. http://hdl.handle.net/2152/3905.
Повний текст джерелаАнотація:
Superelevation transition is often used to help balance the centrifugal forces on vehicles through curved roadway sections. Such transitions have regions with near-zero cross-slope as the pavement cross-section rotates from a negative to positive grade. For drainage of roadway surfaces, regions with near-zero slope constitute 'irregular topography'. This condition promotes extended stormwater runoff drainage path lengths and may result in excessive splash from vehicles and hydroplaning. A critical concern is the effect of longitudinal slope on stormwater drainage through superelevation transition. The overall goal of this study is to provide design guidance on longitudinal slope at superelevation transitions through application of a numerical simulation model of highway drainage. Sheet flow on urban pavement surfaces is very shallow, typically measuring a depth less than one centimeter. For modeling of such flow conditions, any small discontinuity or over-simplification of the surface geometry may result in failure in the flow computation. The kinematic wave approximation to the full Saint-Venant equations is often used in many surface and subsurface water models due to its simplicity in application. However, this model fails when backwater effects, ponding, or flow on reverse slope occurs in the local scale. Furthermore, due to the complexity in the surface geometry and the existence of drainage systems, the kinematic wave model is not sufficient for modeling urban stormwater runoff. On the other hand, the full dynamic wave (DW) model usually requires more computational effort. The long computation time of DW model often compromises the accuracy of the model, making the model practically inefficient. In this study, an algorithm was developed to properly represent the irregularly shaped roadway surfaces near superelevation transition areas with unevenly spaced curvilinear grids based on the geometry profile provided by a roadway design software package such as MicroStation CAD. With this accurately defined geometric representation, a nonlinear hydrodynamic diffusion wave model for hydraulic analysis developed in this research estimates the flow depth and runoff volume on the pavement surfaces. The model computes the flow responses for rising hydrographs using a preconditioned general Conjugate Gradient method. Kinematic boundary conditions developed for the open boundaries at the upstream and downstream boundaries compute the boundary values explicitly at each time step. The result of a numerical experiment shows that the spread and concentration of sheet flow is closely related to the transition in cross slope, longitudinal slope, rainfall intensity, and the width of the road. The characteristics of the sheet flow on superelevation transition areas are analyzed to find the optimal longitudinal slope. It is found that the longitudinal slope in the range of 0.3%-0.4% is the optimal slope at superelevation transition areas which minimizes the depth of stormwater runoff. An example application of the model on a rural highway in Texas is also presented. It is found that a significant amount of stormwater may exist on traffic lanes at the superelevation transitions tested. The predicted ponding depth exceeds the minimum value for potential hydroplaning, and the pattern of the flow concentration may cause differential drag forces on traffic vehicles.text
50
Cui, Gurong. "Rainfall runoff model improvements incorporating a dynamic wave model and synthetic stream networks." Diss., 1999. http://www.newcastle.edu.au/services/library/adt/public/adt-NNCU20030120.144918/index.html.
Повний текст джерела