Physical Sciences and Mathematics Commons^™

Crevice Corrosion Behavior Of Ni-Cr-Mo-W Alloys In Aggressive Environment, Ajit K. Mishra

Electronic Thesis and Dissertation Repository

Ni-Cr-Mo (W) alloys, having an optimum concentration of Cr. Mo and W, are highly corrosion resistant alloys which do not fail by uniform corrosion in aggressive environments. However, when creviced at high applied potential and high temperatures, these materials can be susceptible to crevice corrosion. This study focuses on a family of seven commercial Ni-Cr-Mo (W) alloys containing various amounts of Cr, Mo and W.

Different electrochemical techniques were used to determine the characteristic potentials and temperature which indicate susceptibility to crevice corrosion, and to investigate the individual and synergistic roles of major and minor alloying elements. The corroded alloys …

Representation, Recognition And Collaboration With Digital Ink, Rui Hu

Electronic Thesis and Dissertation Repository

Pen input for computing devices is now widespread, providing a promising interaction mechanism for many purposes. Nevertheless, the diverse nature of digital ink and varied application domains still present many challenges. First, the sampling rate and resolution of pen-based devices keep improving, making input data more costly to process and store. At the same time, existing applications typically record digital ink either in proprietary formats, which are restricted to single platforms and consequently lack portability, or simply as images, which lose important information. Moreover, in certain domains such as mathematics, current systems are now achieving good recognition rates on individual …

Symplectomorphism Groups Of Weighted Projective Spaces And Related Embedding Spaces, Martin L. Vanhoof

Electronic Thesis and Dissertation Repository

In this thesis, we study 4-dimensional weighted projective spaces and homotopy properties of their symplectomorphism groups. Using these computations, we also investigate some homotopy theoretic properties of a few associated embedding spaces. In the classical case of the complex projective plane, Gromov observed that its symplectomorphism group is homotopy equivalent to its subgroup of Kahler isometries. We find that in the case of one singularity, the symplectomorphism group is weakly homotopy equivalent to the Kahler isometry group of a certain Hirzebruch surface, which corresponds to the resolution of the singularity. In the case of multiple singularities, the symplectomorphism groups are …

Polynomially Adjusted Saddlepoint Density Approximations, Susan Zhe Sheng

Electronic Thesis and Dissertation Repository

This thesis aims at obtaining improved bona fide density estimates and approximants by means of adjustments applied to the widely used saddlepoint approximation. Said adjustments are determined by solving systems of equations resulting from a moment-matching argument. A hybrid density approximant that relies on the accuracy of the saddlepoint approximation in the distributional tails is introduced as well. A certain representation of noncentral indefinite quadratic forms leads to an initial approximation whose parameters are evaluated by simultaneously solving four equations involving the cumulants of the target distribution. A saddlepoint approximation to the distribution of quadratic forms is also discussed. By …

Hardware Acceleration Technologies In Computer Algebra: Challenges And Impact, Sardar Anisul Haque

Electronic Thesis and Dissertation Repository

The objective of high performance computing (HPC) is to ensure that the computational power of hardware resources is well utilized to solve a problem. Various techniques are usually employed to achieve this goal. Improvement of algorithm to reduce the number of arithmetic operations, modifications in accessing data or rearrangement of data in order to reduce memory traffic, code optimization at all levels, designing parallel algorithms to reduce span are some of the attractive areas that HPC researchers are working on. In this thesis, we investigate HPC techniques for the implementation of basic routines in computer algebra targeting hardware acceleration technologies. …

Development Of Biodegradable And Stimuli-Responsive Macromolescules And Their Assemblies, Ali Nazemi

Electronic Thesis and Dissertation Repository

Polymersomes are potentially multifunctional soft materials constructed by the self-assembly of amphiphilic block copolymers in aqueous medium. While much research has focused on controlling the assembly and encapsulation properties of polymersomes, their surface functionalization has been relatively unexplored. This is important because it plays a critical role in determining their properties such as toxicity and biodistribution behavior. The work described in this thesis involves the development of a biocompatible and biodegradable polymersome systems based on poly(ethylene oxide)-b-polycaprolactone (PEO-PCL) block copolymers with azide surface groups as a novel scaffold for various biomedical applications. The surface functionalization of these polymersomes …

Spatial Heterogeneities In A Simple Earthquake Fault Model, Javad Kazemian

Electronic Thesis and Dissertation Repository

Natural earthquake fault systems are composed of a variety of materials with different spatial configurations a complicated, inhomogeneous fault surface. The associated inhomogeneities with their physical properties can result in a variety of spatial and temporal behaviors. As a result, understanding the dynamics of seismic activity in an inhomogeneous environment is fundamental to the investigation of the earthquakes processes.

This study presents the results from an inhomogeneous earthquake fault model based on the Olami-Feder-Christensen (OFC) and Rundle-Jackson-Brown (RJB) cellular automata models with long-range interactions that incorporates a fixed percentage of stronger sites, or ‘asperity cells’, into the lattice. These asperity …

Two Dimensional Angular Domain Optical Imaging In Biological Tissues, Eldon Ng

Electronic Thesis and Dissertation Repository

Optical imaging is a modality that can detect optical contrast within a biological sample that is not detectable with other conventional imaging techniques. Optical trans-illumination images of tissue samples are degraded by optical scatter. Angular Domain Imaging (ADI) is an optical imaging technique that filters scattered photons based on the trajectory of the photons. Previous angular filters were limited to one dimensional arrays, greatly limiting the imaging capability of the system.

We have developed a 2D Angular Filter Array (AFA) that is capable of acquiring two dimensional projection images of a sample. The AFA was constructed using rapid prototyping techniques. …

Application Of Computer Algebra In List Decoding, Muhammad Foizul Islam Chowdhury

Electronic Thesis and Dissertation Repository

The amount of data that we use in everyday life (social media, stock analysis, satellite communication etc.) are increasing day by day. As a result, the amount of data needs to be traverse through electronic media as well as to store are rapidly growing and there exist several environmental effects that can damage these important data during travelling or while in storage devices. To recover correct information from noisy data, we do use error correcting codes. The most challenging work in this area is to have a decoding algorithm that can decode the code quite fast, in addition with the …

Photothermal Deflection Spectroscopy Of Amorphous, Nanostructured And Nanocomposite Thin Films, Muhammad Shafiq Ahmed

Electronic Thesis and Dissertation Repository

The energy needs of the modern world are growing day by day, while sources of non-renewable fossil fuels are limited, so there is a need to efficiently use the existing resources and explore renewable energy sources. In order to harvest, store and efficiently utilize renewable energy, we need to explore new materials and improve the performance of existing ones. Among others, hydrogenated amorphous silicon (a-Si:H) with high optical absorption in the visible range of electromagnetic spectrum, is a low cost material for solar cells. But the efficiency of such solar cells is comparatively low because of intrinsic defects associated with …

Potassium Metasomatism At The Polymetallic Nico Deposit, Northwest Territories, Canada, Gregory B. Robinson

Electronic Thesis and Dissertation Repository

High temperature K-metasomatism pervasively replaced Paleoproterozoic volcanic and metasedimentary rocks at Lou Lake NWT. This replacement developed primarily at the structural interface juxtaposing non-metamorphosed Lou Lake volcanic rocks over Treasure Lake Group metasedimentary rocks. This crustal-scale fault developed coeval with the emplacement of anorogenic magmatism within a post-collision extensional setting. Emplacement of porphyry dykes into the fault breccia coincided with K-metasomatism at peak upper-greenschist to amphibolite-facies thermal conditions.

The K-metasomatism resulted from co-mingling of descending crustal fluids and ascending potassic magmatic fluids along the decollement surface. Pervasive K-metasomatism resulted in complete replacement of precursor rocks by potassium feldspar. The pronounced …

Study On The Surface Chemistry Behavior Of Pyrochlore During Froth Flotation, Saeed Chehreh Chelgani

Electronic Thesis and Dissertation Repository

Separation of pyrochlore from its associated minerals is typically accomplished by froth flotation. The surface chemistry of pyrochlore is similar to many of its associated non-value minerals. Therefore, understanding the surface chemical properties of the pyrochlore for selective pyrochlore flotation will potentially aid in the design of flotation strategies for optimized recovery. In this study, pyrochlore samples were collected from various points in the flotation scheme at the Niobec plant, Quebec, Canada. The SEM-EDX analysis revealed that pyrochlore from the Niobec deposit occurs as high and low iron varieties, and that recovery favours varieties with a lower Fe content. To …

Dynamic Light Scattering Study Of Hydroxyapatite Formation: Effect Of Osteopontin And Bone Sialoprotein, Maryam Mozaffari

Electronic Thesis and Dissertation Repository

Biomineralization is the process by which living organisms synthesize minerals. Some bone-related proteins, such as bone sialoprotein (BSP), have been found to enhance biomineralization, while others, including osteopontin (OPN), act as inhibitors of this process. Dynamic light scattering was used to investigate the effect of several native and recombinant proteins and peptides on the formation and growth of hydroxyapatite (HA) crystals from solutions of Ca²⁺ and PO₄^3- ions. We studied two isoforms of OPN, the OPN-derived peptides P0, P3, OPAR and pOPAR, and recombinant BSP. X-ray diffraction was used to identify the precipitate as HA crystals. Native …

Computation Sequences For Series And Polynomials, Yiming Zhang

Electronic Thesis and Dissertation Repository

Approximation to the solutions of non-linear differential systems is very useful when the exact solutions are unattainable. Perturbation expansion replaces the system with a sequences of smaller problems, only the first of which is typically nonlinear. This works well by hand for the first few terms, but higher order computations are typically too demanding for all but the most persistent. Symbolic computation is thus attractive; however, symbolic computation of the expansions almost always encounters intermediate expression swell, by which we mean exponential growth in subexpression size or repetitions. A successful management of spatial complexity is vital to compute meaningful results. …

Cognitive Activity Support Tools: Design Of The Visual Interface, Paul Parsons

Electronic Thesis and Dissertation Repository

This dissertation is broadly concerned with interactive computational tools that support the performance of complex cognitive activities, examples of which are analytical reasoning, decision making, problem solving, sense making, forecasting, and learning. Examples of tools that support such activities are visualization-based tools in the areas of: education, information visualization, personal information management, statistics, and health informatics. Such tools enable access to information and data and, through interaction, enable a human-information discourse. In a more specific sense, this dissertation is concerned with the design of the visual interface of these tools. This dissertation presents a large and comprehensive theoretical framework to …

Investigating The Effects Of Radiation On Phosphonium-Based Ionic Liquids, Susan Howett

Electronic Thesis and Dissertation Repository

This thesis presents work on the understanding of the effects of ionizing radiation on phosphonium-based ionic liquids (ILs). The capability of ILs to dissolve a wide range of molecules, and the potential of ILs to be highly resilient in energy-intensive environments makes them particularly promising media for the separation and sequestration of metal ion contaminants from radioactive waste effluents in nuclear fuel cycles. For this application, a water/IL system will be exposed to a continuous stream of ionizing radiation. The radiation environment will strongly influence the chemical state of the water phase in the system and the chemical parameters affecting …

Impact Craters As Habitats For Life: Endolithic Colonization Of Shocked Gneiss From The Haughton Impact Structure, Devon Island, Canada, Alexandra Janine Pontefract

Electronic Thesis and Dissertation Repository

Meteorite impacts are ubiquitous throughout our solar system and are a fundamental geological process on rocky and icy planetary bodies. Though initially detrimental to biology, an impact event can favourably change the availability and habitability of a substrate for endolithic organisms, which are then able to (re)colonize micro-fractures and pore spaces created during the impact. The colonization of rocks by endolithic communities is an advantageous trait, especially in environments such as hot or cold deserts, where temperature shifts, low water availability and high UV indices pose a significant problem. On Mars, similar conditions – albeit, more extreme – prevail. In …

Application Of Differential And Polarimetric Synthetic Aperture Radar (Sar) Interferometry For Studying Natural Hazards, Samira Alipour

Electronic Thesis and Dissertation Repository

In the following work, I address the problem of coherence loss in standard Differential Interferometric SAR (DInSAR) processing, which can result in incomplete or poor quality deformation measurements in some areas. I incorporate polarimetric information with DInSAR in a technique called Polarimetric SAR Interferometry (PolInSAR) in order to acquire more accurate and detailed maps of surface deformation.

In Chapter 2, I present a standard DInSAR study of the Ahar double earthquakes (M_w=6.4 and 6.2) which occurred in northwest Iran, August 11, 2012. The DInSAR coseismic deformation map was affected by decorrelation noise. Despite this, I employed an advanced …

Solid State Nmr Spectroscopic Studies Of Metal-Organic Frameworks, Peng He

Electronic Thesis and Dissertation Repository

Metal−organic frameworks (MOFs) are a class of novel porous materials with a wide range of chemical applications. Structural characterization is important because understanding the relationship between the properties of these industrially relevant materials and their structures allows one to develop new applications and improve current performance. In this thesis ¹⁷O solid state NMR (SSNMR) spectroscopy is used to differentiate chemically and, under favorite circumstances, crystallographically nonequivalent oxygens and to follow the phase transitions in MOF-based materials. Several cost-effective approaches were used to prepare ¹⁷O-labelled MOFs. The metal centers of MOFs, including ^47/49Ti, ⁶⁷Zn, ⁹¹Zr, ^{115 …}

Image Quality Of Energy-Dependent Approaches For X-Ray Angiography, Jesse Evan Tanguay

Electronic Thesis and Dissertation Repository

Digital subtraction angiography (DSA) is an x-ray-based imaging method widely used for diagnosis and treatment of patients with vascular disease. This technique uses subtraction of images acquired before and after injection of an iodinated contrast agent to generate iodine-specific images. While it is extremely successful at imaging structures that are near-stationary over a period of several seconds, motion artifacts can result in poor image quality with uncooperative patients and DSA is rarely used for coronary applications.

Alternative methods of generating iodine-specific images with reduced motion artifacts might exploit the energy-dependence of x-ray attenuation in a patient. This could be performed …

Fabricating Cost-Effective Nanostructures For Biomedical Applications, Erden Ertorer

Electronic Thesis and Dissertation Repository

In this thesis we described inexpensive alternatives to fabricate nanostructures on planar substrates and provided example applications to discuss the efficiency of fabricated nanostructures.

The first method we described is forming large area systematically changing multi-shape nanoscale structures on a chip by laser interference lithography. We analyzed the fabricated structures at different substrate positions with respect to exposure time, exposure angle and associated light intensity profile. We presented experimental details related to the fabrication of symmetric and biaxial periodic nanostructures on photoresist, silicon surfaces, and ion-milled glass substrates. Behavior of osteoblasts and osteoclasts on the nanostructures was investigated. These results …

Reinforcement Learning With Motivations For Realistic Agents, Jacquelyne T. Forgette

Electronic Thesis and Dissertation Repository

Believable virtual humans have important applications in various fields, including computer based video games. The challenge in programming video games is to produce a non-player controlled character that is autonomous, and capable of action selections that appear human. In this thesis, motivations are used as a basis for learning using reinforcements. With motives driving the decisions of the agents, their actions will appear less structured and repetitious, and more human in nature. This will also allow developers to easily create game agents with specific motivations, based mostly on their narrative purposes. With minimum and maximum desirable motive values, the agents …

The Synthesis And Evaluation Of Peptide-Based Probes For The Imaging Of Rhamm Expressing Carcinoma And Glp-1r On Pancreatic Beta Cells, Ashley Esarik

Electronic Thesis and Dissertation Repository

Peptide-based probes are developed into imaging agents to target two different receptors: receptor for HA mediated motility (RHAMM) and glucagon-like peptide 1 receptor (GLP-1R).

In the first project, peptides are derived from tubulin and mimic HA (hyaluronan), the natural ligand of RHAMM. In order to develop the lead candidate peptides into imaging agents, a DOTA chelator which can coordinate a radiometal was coupled onto the lead peptides. Gallium labelling studies were performed and the labelled probes were used in in vivo mouse studies. Various analogues of two of the candidate peptides were also synthesized using bioisosteric, unnatural as well as …

Vehicular Instrumentation And Data Processing For The Study Of Driver Intent, Taha Kowsari

Electronic Thesis and Dissertation Repository

The primary goal of this thesis is to provide processed experimental data needed to determine whether driver intentionality and driving-related actions can be predicted from quantitative and qualitative analysis of driver behaviour. Towards this end, an instrumented experimental vehicle capable of recording several synchronized streams of data from the surroundings of the vehicle, the driver gaze with head pose and the vehicle state in a naturalistic driving environment was designed and developed. Several driving data sequences in both urban and rural environments were recorded with the instrumented vehicle. These sequences were automatically annotated for relevant artifacts such as lanes, vehicles …

Stochastic Simulation And Spatial Statistics Of Large Datasets Using Parallel Computing, Jonathan Sw Lee

Electronic Thesis and Dissertation Repository

Lattice models are a way of representing spatial locations in a grid where each cell is in a certain state and evolves according to transition rules and rates dependent on a surrounding neighbourhood. These models are capable of describing many phenomena such as the simulation and growth of a forest fire front. These spatial simulation models as well as spatial descriptive statistics such as Ripley's K-function have wide applicability in spatial statistics but in general do not scale well for large datasets. Parallel computing (high performance computing) is one solution that can provide limited scalability to these applications. This is …

Investigating The Influence Of Interface And Vacancy Defects On The Growth Of Silicon Quantum Dots In Sio2, John Phelan

Electronic Thesis and Dissertation Repository

The effects of interface and vacancy defects on silicon quantum dot (Si-QD) growth are investigated using measurements of Time Resolved Photoluminescence (TRPL), Photoluminescence (PL) Spectroscopy and Electron Paramagnetic Resonance (EPR). Thermally grown SiO₂ thin films (280nm) were irradiated with high energy (400keV – 1MeV) silicon ions in order to introduce defects into the Si-QD growth layer of SiO₂. A noticeable increase in PL emission intensity is seen with the highest energy pre-implanted sample over a single implant sample. TRPL results show increased radiative lifetimes for the lower energy (400keV) pre-implant while little or no difference is seen …

Stable Isotope Ecology And Human-Animal Interactions In Northern Peru, Paul Szpak

Electronic Thesis and Dissertation Repository

This dissertation addresses several issues related to isotopic ecology in northern Peru. The first portion of the dissertation focuses on baseline carbon and nitrogen isotopic variability in plants for comparison with paleodietary data. The second portion applies these data to assess animal management practices (camelids) in the Virú Valley on the north coast of Peru using isotopic analysis of bone collagen and serially sampled hair. A detailed survey of plants from the Moche River Valley region demonstrates significant east-west variation in plant carbon and nitrogen isotopic compositions, following changes in altitude from the Pacific coast to the highlands. A growth …

Collaborative Policy-Based Autonomic Management In Iaas Clouds, Omid Mola

Electronic Thesis and Dissertation Repository

With the increasing number of "machines" (either virtual or physical) in a computing environment, it is becoming harder to monitor and manage these resources. Relying on human administrators, even with tools, is expensive and the growing complexity makes management even harder. The alternative is to look for automated approaches that can monitor and manage computing resources in real time with no human intervention. One of the approaches to this problem is policy-based autonomic management. However, in large systems having one single autonomic manager to manage everything is almost impossible. Therefore, multiple autonomic managers will be needed and these will need …

Valuation Of The Peterborough Prison Social Impact Bond, Majid Hasan

Electronic Thesis and Dissertation Repository

The Peterborough Prison Bond is a social impact bond (SIB) that was issued by the UK government to reduce recidivism rate in the Peterborough prison. Most of the literature on the SIB so far has been focused on the opportunities, challenges, and the related policy issues (see (Fox), (Strickland), and (Disley)), and little effort has been made to provide a mathematical framework to determine a fair price for such instruments. Here, we aim to provide a pricing framework for the bond. We price the bond both from the issuer's and the buyer's perspective, by adjusting for the bond's risk, ambiguity, …

Functionalized Polyisobutylene: From Synthesis To Properties And Applications, Solmaz Karamdoust

Electronic Thesis and Dissertation Repository

Polyisobutylene (PIB) is a polymer well known for its desirable properties such as high chemical stability, impermeability to gases, and biocompatibility in certain applications. However in some applications it is limited by properties such as high hydrophobicity, lack of chemical functionalities, and the adsorption of proteins and organisms to its surface. Butyl rubber (IIR) is a copolymer of isobutylene (IB) with small percentages of isoprene (IP). Typically these IP units serve as sites for the covalent cross-linking of the IIR, in addition can serve as sites for further functionalization of IIR. These modifications can expand the potential applications of IIR. …