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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Investigation of stormwater particles generated from common urban surfaces

Brodie, Ian January 2007 (has links)
[Abstract]: Pollution due to urban stormwater runoff is a significant environmental issue. Large regional devices including sediment ponds and constructed wetlands are common features in the urban landscape to treat runoff. In keeping with this approach, data requirements to evaluate stormwater impacts have mainly been met by the monitoring of sizeable urban catchments, typically greater than 10ha in area. Urban runoff characteristics have thus been conventionally linked with broadly defined catchment attributes. Land use, as defined by zonings such as Residential, Commercial and Industrial, is an attribute often used to evaluate stormwater runoff from urban catchments.The emergence of Water Sensitive Urban Design (WSUD) in Australia is changing the management focus from the reliance on a small number of large-scale devices to many smaller-scale source controls distributed throughout the catchment. This paradigm shift in stormwater management places greater emphasis on small-scale processes within urban areas. Subsequently there is a need for more knowledge about stormwater generated from specific urban surfaces (roads, roofs, grassed areas etc).The objective of this study was to demonstrate how urban stormwater quality can be managed on the basis of urban surfaces. The study involved the collection of data for typical urban surfaces and the development of predictive models to estimate stormwater quality. A series of case studies is provided to illustrate the use of surface-related data and modelling tools in stormwater management, particularly in the context of WSUD.Non-Coarse Particles (NCP), defined as suspended solids less than 500μm in size, was selected as the stormwater pollutant under consideration. NCP is divided into the following particle size classes; Very Fine Particles (VFP, <8μm), Fine Particles (FP, 8-63μm) and Medium Particles (MP, 63-500μm). Laboratory methods to determine the concentration of these particle classes within stormwater runoff were adapted and refined from current standard methods. Organic content of each stormwater particle class was also determined.An innovative device, the flow splitter, was developed to collect runoff samples from urban surfaces. The flow splitter was designed to obtain a composite flow-proportional sample, necessary to derive the Event Mean Concentration of stormwater particles. Hydraulic and sediment testing of a prototype flow splitter confirmed that the device is an accurate and unbiased sampling method.Flow splitters were installed at five monitoring sites within inner city Toowoomba, Australia. The sites have small catchments (50 to 450m2 area) representative of urban impervious areas (galvanized iron roof, concrete carpark and bitumen road pavement) and pervious areas (grassed and exposed bare soil). Overall, runoff from 40 storms with rainfalls from 2.5mm to 64.3mm was sampled during the period December 2004 to January 2006.A scatter plot analysis identified potential correlations between measured NCP loads and basic rainfall parameters such as rainfall depth and intensity. An exponential-type trend, consistent with many washoff models, is evident between load and average rainfall intensity for all surfaces. A composite index, referred to as the Rainfall Detachment Index (RDI), was found to be better than average rainfall intensity in explaining a relationship between NCP load and storm rainfall characteristics.The insight gained from the RDI led to the development of a particle Mass Balance Model for impervious surfaces. Depending on the surface type, the model was able for provide reasonable estimates (R2 = 0.74 to 0.97) against the measured NCP loads. Simpler analytical methods for particle load estimation were also developed in the study. A total of five methods were produced. An error analysis was conducted to compare the performance of each method to accurately reproduce the measured NCP loads. The analysis also included three methods used in current practice, which performed poorly compared to the new modelling techniques.The analytical methods provide useful tools in urban stormwater planning. The Mass Balance Model and measured surface-specific data were used in a number of case study examples to demonstrate possible applications. The applications included assessments of 1) the relative contribution that different urban surfaces make to the particle load in runoff; 2) how surface-specific data can be directly transferred to represent a large-scale urban catchment located in a different climate; 3) the particle loads generated from Residential and Commercial land uses; 4) the effect of exposed areas of bare soil on the particle loads from a Residential catchment; 5) the effect that widespread adoption of rainwater tanks may have on particle concentration in Residential urban runoff and 6) the particle load reductions by the use of a grass swale to treat road runoff.
112

Estimation of mixing and mixed distributions /

Millar, R. B. January 1989 (has links)
Thesis (Ph. D.)--University of Washington, 1989. / Vita. Includes bibliographical references.
113

Efficiency based adaptive tests for censored survival data /

Pecková, Monika. January 1997 (has links)
Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [122]-125).
114

Reduced dimensionality hyperspectral classification using finite mixture models

Jayaram, Vikram, January 2009 (has links)
Thesis (Ph. D.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.
115

Predicting alcohol relapse using nonlinear dynamics and growth mixture modeling /

Witkiewitz, Katie. January 2005 (has links)
Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 119-134).
116

Likelihood ratio test for the presence of cured individuals : a simulation study /

Liang, Yi, January 2002 (has links)
Thesis (M.A.S.)--Memorial University of Newfoundland, 2003. / Bibliography: leaves 48-50. Also available online.
117

Clustering with mixed variables /

Soong Uk Chang. January 2005 (has links) (PDF)
Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.
118

Tests of the Efficient Markets Hypothesis

Reschenhofer, Erhard, Hauser, Michael A. January 1997 (has links) (PDF)
This paper surveys various statistical methods that have been proposed for the examination of the efficiency of financial markets and proposes a novel procedure for testing the predictability of a time series. For illustration, this procedure is applied to Austrian stock return series.
119

A DERIVATION OF THE PERCENTILE BASED TUKEY DISTRIBUTIONS AND A COMPARISON OF MONOTONIC VERSUS NONMONOTONIC AND RANK TRANSFORMATIONS

Ptukhin, Yevgeniy 01 August 2018 (has links)
The Method of Moments (MOM) has been extensively used in statistics for obtaining conventional moment-based estimators of various parameters. However, the disadvantage of this method is that the estimates “can be substantially biased, have high variance, or can be influenced by outliers” (Headrick & Pant, 2012). The Method of Percentiles (MOP) provides a useful alternative to the MOM when the distributions are non-normal, specifically being more computationally efficient in terms of estimating population parameters. Examples include the generalized lambda distribution (Karian & Dudewicz, 1999), third order power method (Koran, Headrick & Kuo, 2015) and fifth order power method (Kuo & Headrick, 2017). Further, the HH, HR and HQ distributions, as extensions of the Tukey g-h (GH) family, are of interest for investigation using the MOP in this dissertation. More specifically, closed form solutions are obtained for left-right tail-weight ratio (a skew function) and tail-weight factor (a kurtosis function). A Monte Carlo simulation study which includes the comparison of monotonic and nonmonotonic transformation scenarios is also performed. The effect on Type 1 error and power rates under severely nonmonotonic scenarios are of special interest in the study. Dissimilarities of not strictly monotonic scenarios are discussed. The empirical confirmation that Rank Transform (RT) is appropriate for 2x2 designs is obtained.
120

Quantitative Evaluation of Software Quality Metrics in Open-Source Projects

Barkmann, Henrike January 2009 (has links)
The validation of software quality metrics lacks statistical significance. One reason for this is that the data collection requires quite some effort. To help solve this problem, we develop tools for metrics analysis of a large number of software projects (146 projects with ca. 70.000 classes and interfaces and over 11 million lines of code). Moreover, validation of software quality metrics should focus on relevant metrics, i.e., correlated metrics need not to be validated independently. Based on our statistical basis, we identify correlation between several metrics from well-known objectoriented metrics suites. Besides, we present early results of typical metrics values and possible thresholds.

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