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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.
21

The hydrogeological context of cemetery operations and planning in Australia.

Dent, Boyd B. January 2002 (has links)
The purpose of this research has been to evaluate the potential contamination impact of cemeteries on groundwater. A comprehensive study of the groundwaters in the unsaturated and saturated zones of nine Australian cemeteries has been made, with most sampling between October 1996 and August 1998. Periodic sampling from 83 wells or ponds yielded 305 complete samples which were tested for at least 38 inorganic and 5 bacterial analytes. Other, partially complete samples were used for metals and bacterial analyses. The soils of all sites were tested for a range of analytes that might reflect or affect the presence of human decomposition products. The within-cemetery sampling has allowed inorganic chemical characterisation of cemetery groundwaters to an amount of detail not previously attained. In the past 100 years there have been fewer than 12 sampling-based studies published on any of these matters. The forms of nitrogen feature most prominently, but three groupings of analytes are recognised as major contributors, including Na, Mg, Sr, Cl, SO4 and forms of P; these outcomes are similar in each hydrogeological zone. This study is unique in that it has a broad focus on the environmental impacts in respect of bacterial presence and transmission, heavy metals and nutrients, and has put these into the context of cemetery management and operational practices. Cemetery functions are best understood conceptually as a special kind of landfill but they are strongly influenced by the temporal and spatial variability of cemetery practices. Human decomposition mechanisms and products are considered in detail. This information was used to model the impacts for a large municipal cemetery over a twenty year time-frame. The previously unquantified relationship of cemetery proximity to drinking water wells has been determined and guiding principles for cemetery location and operation have been prepared including separation distances from watertables and specification of buffer zones in different hydrogeological settings. The related issue of the disposition of cremated remains is also considered and guidelines developed for scattering of these within buffer zones. The amounts of decomposition products leaving cemeteries are very small, and well sited and managed cemeteries have a low impact on the environment. Cemeteries should not be regarded as a detrimental landuse and the in-soil interment of human remains and re-use of graves are sustainable activities. However, almost all cemeteries have some potential for pollution. The most serious situation is the escape of pathogenic bacteria or viruses into the environment at large. The answer to the question as to ‘whether any one cemetery pollutes?’ depends on the location and operation of the site in adherence to the affecting parameters. The question can only be resolved by a comprehensive geoscientific investigation with a focus on the hydrogeological setting. Such assessment needs to consider the effects if the practices and/or usage patterns within the cemetery change, or if there are unaccounted changes in impacting natural phenomena like floods.
22

Thermocatalytic decomposition of vulcanized rubber

Qin, Feng 25 April 2007 (has links)
Used vulcanized rubber tires have caused serious trouble worldwide. Current disposal and recycling methods all have undesirable side effects, and they generally do not produce maximum benefits. A thermocatalytic process using aluminum chloride as the main catalyst was demonstrated previously from 1992 to 1995 in our laboratory to convert used rubber tire to branched and ringed hydrocarbons. Products fell in the range of C4 to C8. Little to no gaseous products or fuel oil hydrocarbons of lower value were present. This project extended the previous experiments to accumulate laboratory data, and provide fundamental understanding of the thermocatalytic decomposition reaction of the model compounds including styrene-butadiene copolymers (SBR), butyl, and natural rubber. The liquid product yields of SBR and natural rubber consistently represented 20 to 30% of the original feedstock by weight. Generally, approximately 1 to 3% of the feedstock was converted to naphtha, while the remainder was liquefied petroleum gas. The liquid yields for butyl rubber were significantly higher than for SBR and natural rubber, generally ranging from 30 to 40% of the feedstock. Experiments were conducted to separate the catalyst from the residue by evaporation. Temperatures between 400 °C and 500 °C range are required to drive off significant amounts of catalyst. Decomposition of the catalyst also occurred in the recovery process. Reports in the literature and our observations strongly suggest that the AlCl3 forms an organometallic complex with the decomposing hydrocarbons so that it becomes integrated into the residue. Catalyst mixtures also were tested. Both AlCl3/NaCl and AlCl3/KCl mixtures had very small AlCl3 partial pressures at temperatures as high as 250 °C, unlike pure AlCl3 and AlCl3/MgCl2 mixtures. With the AlCl3/NaCl mixtures, decomposition of the rubber was observed at temperatures as low as 150 °C, although the reaction rates were considerably slower at lower temperatures. The amount of naphtha produced by the reaction also increased markedly, as did the yields of aromatics and cyclic paraffin. Recommendations are made for future research to definitively determine the economic and technical feasibility of the proposed thermocatalytic depolymerization process.
23

Biochemical alteration of gravesoils between season and soil type

Benninger, Laura 01 July 2009 (has links)
Decomposition chemistry refers to the biochemical degradation processes which occur in soft tissue as decomposition proceeds. This study aims to investigate the relationship between the release of decomposition fluids into contrasting soil environments and their potential correlation with the presence of a decomposing carcass. Soil from two different carcass decomposition trials was utilized to determine if seasonal and soil variation altered the soils reaction to a carcass. The reaction was determined by investigating the soil available phosphorus, extractable lipid-phosphate, pH, moisture and fatty acid content. A significant increase in the relative concentration of extractable lipid-phosphate, soil available phosphorus, and fatty acid content was identified, confirming the flux in the microbial biomass in the soil. Contrary to these nutrients, there were no notable changes in the soil pH and moisture content. The findings of this study were able to highlight the future forensic potential of these techniques and demonstrate a need for further research.
24

Towards a Unified Signal Representation via Empirical Mode Decomposition

Gao, Jiexin 20 November 2012 (has links)
Empirical mode decomposition was proposed recently as a time frequency analysis tool for nonlinear and nonstationary signals. Despite from its many advantages, problems such as “uniqueness” problem have been discovered which limit the application. Although this problem has been addressed to some extent by various extensions of the original algorithm, the solution is far from satisfactory in some scenarios. In this work we propose two variants of the original algorithm, with emphasis on providing unified representations. R-EMD makes use of a set of reference signals to guide the decomposition therefore guarantees unified representation for multiple 1D signals. 2D- BEMD takes advantage of a projection procedure and is capable of providing unified representation between a pair of 2D signals. Application of the proposed algorithms on different problems in biometric and image processing demonstrates promising results and indicates the effectiveness of the proposed framework.
25

The Design of a New Program Decomposition Mechanism for Processor-in-Memory Systems

Liu, Ying-Bo 26 August 2002 (has links)
In recent years, many researchers had proposed a new class of computer architecture, called processor-in-memory (PIM), to reduce the performance gap between the CPU and memory. In order to exploit the benefits of PIM, we designed a parallelizing system ¡V SAGE (Statement Analysis Grouping Evaluation) in our previous research. In this paper, we design a program decomposition mechanism for SAGE system. The mechanism partitions the statements in a program into several parts according to control flow relation. Then it analyzes data dependence relation by using Polaris system, and generates weighted partition dependence graphs which are scheduled by task scheduling mechanisms of SAGE system.
26

Thermocatalytic decomposition of vulcanized rubber

Qin, Feng 25 April 2007 (has links)
Used vulcanized rubber tires have caused serious trouble worldwide. Current disposal and recycling methods all have undesirable side effects, and they generally do not produce maximum benefits. A thermocatalytic process using aluminum chloride as the main catalyst was demonstrated previously from 1992 to 1995 in our laboratory to convert used rubber tire to branched and ringed hydrocarbons. Products fell in the range of C4 to C8. Little to no gaseous products or fuel oil hydrocarbons of lower value were present. This project extended the previous experiments to accumulate laboratory data, and provide fundamental understanding of the thermocatalytic decomposition reaction of the model compounds including styrene-butadiene copolymers (SBR), butyl, and natural rubber. The liquid product yields of SBR and natural rubber consistently represented 20 to 30% of the original feedstock by weight. Generally, approximately 1 to 3% of the feedstock was converted to naphtha, while the remainder was liquefied petroleum gas. The liquid yields for butyl rubber were significantly higher than for SBR and natural rubber, generally ranging from 30 to 40% of the feedstock. Experiments were conducted to separate the catalyst from the residue by evaporation. Temperatures between 400 °C and 500 °C range are required to drive off significant amounts of catalyst. Decomposition of the catalyst also occurred in the recovery process. Reports in the literature and our observations strongly suggest that the AlCl3 forms an organometallic complex with the decomposing hydrocarbons so that it becomes integrated into the residue. Catalyst mixtures also were tested. Both AlCl3/NaCl and AlCl3/KCl mixtures had very small AlCl3 partial pressures at temperatures as high as 250 °C, unlike pure AlCl3 and AlCl3/MgCl2 mixtures. With the AlCl3/NaCl mixtures, decomposition of the rubber was observed at temperatures as low as 150 °C, although the reaction rates were considerably slower at lower temperatures. The amount of naphtha produced by the reaction also increased markedly, as did the yields of aromatics and cyclic paraffin. Recommendations are made for future research to definitively determine the economic and technical feasibility of the proposed thermocatalytic depolymerization process.
27

Integer programming models for the branchwidth problem

Ulusal, Elif 10 October 2008 (has links)
We consider the problem of computing the branchwidth and an optimal branch decomposition of a graph. Branch decompositions and branchwidth were introduced in 1991 by Robertson and Seymour and were used in the proof of Graph Minors Theorem (GMT), a well known conjecture (Wagner's conjecture) in graph theory. The notions of branchwidth and branch decompositions have been proved to be useful for solving many NP-hard problems that have applications in fields such as graph theory, network design, sensor networks and biology. Branch decompositions have been utilized for problems such as the traveling salesman problem by Cook and Seymour, general minor containment and the branchwidth problem by Hicks by means of the relevant branch decomposition-based algorithms. Branch decomposition-based algorithms are fixed parameter tractable algorithms obtained by combining dynamic programming techniques with branch decompositions. The running time and space of these algorithms strongly depend on the width of the utilized branch decomposition. Thus, finding optimal or close to optimal branch decompositions is very important for the efficiency of the branch decomposition-based algorithms. Motivated by the vastness of the fields of application, we aim to increase the efficiency of the branch decomposition-based algorithms by investigating effective techniques to find optimal branch decompositions. We present three integer programming models for the branchwidth problem. Two similar formulations are based on the relationship of branchwidth problem with a special case of the Steiner tree packing problem. The third formulation is based on the notion of laminar separations. We utilize upper and lower bounds obtained by heuristic algorithms, reduction techniques and cutting planes to increase the efficiency of our models. We use all three models for the branchwidth problem on hypergraphs as well. We compare the performance of three models both on graphs and hypergraphs. Furthermore we use the third model for rank-width problem and also offer a heuristic for finding good rank decompositions. We provide computational results for this problem, which can be a basis of comparison for future formulations.
28

Efficient and portable parallel algorithms for Cholesky decomposition /

Chu, Pei Yue Liu. January 2003 (has links)
Thesis (Ph. D.)--Lehigh University, 2003. / Includes vita. Includes bibliographical references (leaves 90-103).
29

A study of the determination of fluorine and other constituents in fluorspar

Grantham, Robert Knowlton. January 1929 (has links) (PDF)
Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1929. / Page number 23 is repeated twice in the paging. The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed Dec. 11, 2009). Includes bibliographical references (p. 35).
30

Investigating methods of partial fraction decomposition

Newberry, Anthony David 02 February 2012 (has links)
Abstract Investigating Methods of Partial Fraction Decomposition Anthony David Newberry, MA The University of Texas at Austin, 2011 Supervisor: Efraim Armendariz This report discusses the history of partial fractions. The paper investigates several methods of solving partial fraction decomposition problems. First, the basic method taught in most calculus courses is addressed. Another method addressed is a substitution method in which a clever substitution is used to transform expressions into something more easily integrable. Then, a rationale for partial fraction decomposition is given that includes a number theory perspective, a calculus perspective, and an algebraic perspective. A fourth method discussed involves using derivatives. / text

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