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Now showing items 61-70 of 4022

#### Interaction of Chemical Oxidants with Aquifer Materials

(University of Waterloo, 2006)

In situ chemical oxidation (ISCO) is a leading-edge technology for soil and groundwater remediation, and involves injecting a chemical oxidant (e. g. , permanganate, hydrogen peroxide, or persulfate) into the subsurface ...

#### Experimental and Modelling Investigation of a Novel Tetrafunctional Initiator in Free Radical Polymerization

(University of Waterloo, 2005)

An experimental and modelling investigation of a tetrafunctional initiator designed for free radical polymerizations is presented. Multifunctional initiators are believed to provide two advantages over traditional ...

#### Subcellular localization and protein-protein interactions of two methyl recycling enzymes from Arabidopsis thaliana

(University of Waterloo, 2011-01-21)

This thesis documents the subcellular localization and protein-protein interactions of two methyl recycling enzymes. These two enzymes, adenosine kinase (ADK) and S-adenosyl-L-homocysteine hydrolase (SAHH), are essential ...

#### Nonlinear Dimensionality Reduction with Side Information

(University of Waterloo, 2006)

In this thesis, I look at three problems with important applications in data processing. Incorporating side information, provided by the user or derived from data, is a main theme of each of these problems. <br /><br ...

#### The Continuum Architecture: Towards Enabling Chaotic Ubiquitous Computing

(University of Waterloo, 2005)

Interactions in the style of the ubiquitous computing paradigm are possible today, but only in handcrafted environments within one administrative and technological realm. This thesis describes an architecture (called ...

#### Design, Optimization and Fabrication of Amorphous Silicon Tunable RF MEMS Inductors and Transformers

(University of Waterloo, 2007-01-19)

High performance inductors are playing an increasing role in modern communication systems. Despite the superior performance offered by discrete components, parasitic capacitances from bond pads, board traces and packaging ...

#### Chlorine, Fluorine and Water in the Stratosphere: Chemistry, Transport and Trends based on ACE-FTS measurements

(University of Waterloo, 2006)

The Atmospheric Chemistry Experiment (ACE) is a satellite mission for remote sensing of the Earth's atmosphere using the solar occultation technique. The primary instrument on this satellite is the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS). ACE-FTS retrievals are described with a focus on the creation of

**a priori**temperature and pressure profiles. ACE-FTS measurements are then used to investigate the chemistry, transport and trends of chlorine, fluorine and water in the stratosphere, leading to an improved understanding of processes affecting both stratospheric ozone depletion and global climate change. <br /><br /> Total chlorine (Cl<sub>TOT</sub>) in the stratosphere is determined using ACE-FTS measurements of eleven chlorine-containing species, supplemented by both other measurements and models, to determine Cl<sub>TOT</sub> as a function of altitude in five latitude zones. All resulting Cl<sub>TOT</sub> profiles are nearly linear, with a slight slope. Mean Cl<sub>TOT</sub> for 2004 is determined to be 3. 65 ppbv for both the northern and southern midlatitudes (with a precision and estimated accuracy of ±0. 09 and ±0. 13 ppbv, respectively). A slightly lower value of mean Cl<sub>TOT</sub> is determined for the tropics and slightly higher values at high latitudes. Total fluorine (F<sub>TOT</sub>) in the stratosphere is also determined primarily from ACE-FTS measurements using a similar approach, resulting in stratospheric F<sub>TOT</sub> profiles which are nearly linear with mean values ranging from 2. 50 to 2. 59 ppbv for each latitude zone (with a precision of 0. 04-0. 07 ppbv and an estimated accuracy of 0. 15 ppbv). The observed slopes and pattern of latitudinal variation are evidence of the beginning of a decline in global stratospheric chlorine and of the continuing increase in global stratospheric fluorine levels. <br /><br /> The abundance of water in the stratosphere is investigated for the northern hemisphere midlatitudes in 2004 using ACE-FTS measurements. Potential water is determined as [H<sub>2</sub>O]+2[CH<sub>4</sub>] and from [H<sub>2</sub>O] versus [CH<sub>4</sub>] correlations, resulting in a value of 7. 14±0. 05 ppmv, which is used to determine a value of 3. 65±0. 15 ppmv for the mean abundance of water entering the stratosphere. Both values are compared directly with historical data from the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument (1985-1994) and show a negligible change, implying that the increases observed by ATMOS and other long-term measurements from that time period have not continued. <br /><br /> The removal of stratospheric water in the Arctic vortex is investigated using ACE-FTS measurements. Using derived quantities from a meteorological data assimilation, northern hemisphere occultations from early 2004 are classified as vortex, vortex edge or extravortex. [CH<sub>4</sub>] versus [N<sub>2</sub>O] correlations are used to further classify the extravortex occultations as tropical, subtropical or midlatitude. Comparisons between profiles of [N<sub>2</sub>O], [CH<sub>4</sub>] and [H<sub>2</sub>O] inside and outside the Arctic vortex, give estimates of upper stratospheric and lower mesospheric descent rates, indicating that descent in the winter 2004 Arctic vortex was rapid, with evidence of descent at higher altitudes than in past years. <br /><br /> The dehydration of air in the tropical tropopause layer and mechanisms for the entry of water vapor into the stratosphere are investigated by an analysis of ACE-FTS profiles of temperature, water vapor and [HDO]/[H<sub>2</sub>O]. Month-to-month comparisons for 2004 and 2005 reveal a clear pattern of seasonal variation and a correlation between minimum temperature and maximum HDO depletion. Further interpretation indicates that the gradual dehydration mechanism accompanied by lofting of ice particles in the tropical troposphere is the most likely explanation for the observed seasonal variation and the shape of the [HDO]/[H<sub>2</sub>O] profiles....#### Reconstruction and Visualization of Polyhedra Using Projections

(University of Waterloo, 2005)

Two types of problems are studied in this thesis: reconstruction and visualization of polygons and polyhedra. <br /><br /> Three problems are considered in reconstruction of polygons and polyhedra, given a set of projection characteristics. The first problem is to reconstruct a closed convex polygon (polyhedron) given the number of visible edges (faces) from each of a set of directions

**S**. The main results for this problem include the necessary and sufficient conditions for the existence of a polygon that realizes the projections. This characterization gives an algorithm to construct a feasible polygon when it exists. The other main result is an algorithm to find the maximum and minimum size of a feasible polygon for the given set**S**. Some special cases for non-convex polygons and for perspective projections are also studied. <br /><br /> For reconstruction of polyhedra, it is shown that when the projection directions are co-planar, a feasible polyhedron (i. e. a polyhedron satisfying the projection properties) can be constructed from a feasible polygon and vice versa. When the directions are covered by two planes, if the number of visible faces from each of the directions is at least four, then an algorithm is presented to decide the existence of a feasible polyhedron and to construct one, when it exists. When the directions see arbitrary number of faces, the same algorithm works, except for a particular sub-case. <br /><br /> A polyhedron is, in general, called equiprojective, if from any direction the size of the projection or the projection boundary is fixed, where the "size" means the number of vertices, edge, or faces. A special problem on reconstruction of polyhedra is to find all equiprojective polyhedra. For the case when the size is the number of vertices in the projection boundary, main results include the characterization of all equiprojective polyhedra and an algorithm to recognize them, and finding the minimum equiprojective polyhedra. Other measures of equiprojectivity are also studied. <br /><br /> Finally, the problem of efficient visualization of polyhedra under given constraints is considered. A user might wish to find a projection that highlights certain properties of a polyhedron. In particular, the problem considered is given a set of vertices, edges, and/or faces of a convex polyhedron, how to determine all projections of the polyhedron such that the elements of the given set are on the projection boundary. The results include efficient algorithms for both perspective and orthogonal projections, and improved adaptive algorithm when only edges are given and they form disjoint paths. A related problem of finding all projections where the given edges, faces, and/or vertices are not on the projection boundary is also studied....#### Development of a Packed-bed Reactor Containing Supported Sol-gel Immobilized Lipase for Transesterification

(University of Waterloo, 2013-01-10)

The objective of this work was to develop a novel enzyme immobilization scheme for supported lipase sol-gels and to evaluate the potential of the immobilized biocatalyst for the production of biodiesel in a packed bed ...

#### Reintegrating Canadian Agriculture and Ecological Land Management

(University of Waterloo, 2012-09-21)

There are three distinct motivating factors behind this research: 1) ecosystems are threatened across Canada and require locations within which to establish or re-establish natural features to support native species; 2) ...