Physical Sciences and Mathematics Commons^™

Functional Nanoporous Polyamide Aerogels, Malik Adnan Saeed

Doctoral Dissertations

"Aerogels are low-density materials consisting of 3D assemblies of nanoparticles with high open porosities and surface areas. Inspired by the extraordinary mechanical strength of polymer crosslinked aerogels, our recent attention is focused on inexpensive multifunctional isocyanates reacting with a variety of aromatic, organometallic and inorganic monomers. Three such systems discussed here are:

(A) Polymeric aerogels synthesized via a room temperature reaction of an aromatic triisocyanate with pyromellitic acid. Using solid-state CPMAS ¹³C and ¹⁵N NMR, it was found that the skeletal framework was a statistical co-polymer of polyamide, polyurea and polyimide. Stepwise pyrolytic decomposition followed by reactive etching …

Identifying Shallow Subsurface Stratigraphy And Voids Using Dispersive Characteristics Of Electromagnetic And Surface Waves, Payman Hajiani

Doctoral Dissertations

"This dissertation presents the results of three manuscripts on spectral analysis of electromagnetic and seismic surface waves to detect subsurface stratigraphy and voids. In the first manuscript, a new technique was developed by utilizing spectral analysis of surface waves to detect subsurface openings. This technique applied the concept of group delay to evaluate the effects of subsurface voids on the phase shift domain. Seismic data sets were acquired at different sites where the shape, size, and depth of the void varied. In all surveys, the time delay technique precisely identified the locations of the subsurface openings. The second manuscript presents …

Small Sample Confidence Bands For The Survival Functions Under Proportional Hazards Model, Emad Mohamed Abdurasul

Doctoral Dissertations

"In this work, a saddlepoint-based method is developed for generating small sample confidence bands for the population survival function from the Kaplan-Meier (KM), the product limit (PL), and Abdushukurov-Cheng-Lin (ACL) survival function estimators, under the proportional hazards model. In the process the exact distribution of these estimators is derived and developed mid-population tolerance bands for said estimators. The proposed saddlepoint method depends upon the Mellin transform of the zero-truncated survival estimator which is derived for the KM, PL, and ACL estimators. These transforms are inverted via saddlepoint approximations to yield highly accurate approximations to the cumulative distribution functions of the …

Integrated Geophysical Approach Using Electrical Resistivity Tomography And Multichannel Analysis Of Surface Wave In Assessing Wilson Spring Development, Ibrahim E. Ahmed

Doctoral Dissertations

"This research investigated fractured zones leading to preferential flow paths of Wilson Spring. In this context, electrical resistivity tomography (ERT) data and multi-channel analyses of surface waves (MASW) data were acquired at studied site with the purpose of mapping a variable depth to top of bedrock and geological structures.

Interpretation of the boreholes, MASW, and ERT data indicated that a depth to top of rock does vary significantly at the studied site due to many solution-widened fractures. Multiple near-vertical solution-widened fractures were mapped in the studied site based on the interpretation of the ERT data. The mapped solution-widened fractures appear …

Existence And Classification Of Nonoscillatory Solutions Of Two Dimensional Time Scale Systems, Özkan Özturk

Doctoral Dissertations

"During the past years, there has been an increasing interest in studying oscillation and nonoscillation criteria for dynamic equations and systems on time scales that harmonize the oscillation and nonoscillation theory for the continuous and discrete cases in order to combine them in one comprehensive theory and eliminate obscurity from both.

We not only classify nonoscillatory solutions of dynamic equations and systems on time scales but also guarantee the (non)existence of such solutions by using the Knaster fixed point theorem, Schauder - Tychonoff fixed point theorem, and Schauder fixed point theorem. The approach is based on the sign of nonoscillatory …

Geophysical Imaging Of Karst Features In Missouri, Jeremiah Chukwunonso Obi

Doctoral Dissertations

"Automated electrical resistivity tomography (ERT) supported with multichannel analysis of surface waves (MASW) and boring data were used to map karst related features in Missouri in order to understand karst processes better in Missouri. Previous works on karst in Missouri were mostly surficial mapping of bedrock outcrops and joints, which are not enough to define the internal structure of karst system, since most critical processes in karst occur underground. To understand these processes better, the density, placement and pattern of karst related features like solution-widened joints and voids, as well as top of bedrock were mapped. In the course of …

Detecting, Segmenting And Tracking Bio-Medical Objects, Mingzhong Li

Doctoral Dissertations

"Studying the behavior patterns of biomedical objects helps scientists understand the underlying mechanisms. With computer vision techniques, automated monitoring can be implemented for efficient and effective analysis in biomedical studies. Promising applications have been carried out in various research topics, including insect group monitoring, malignant cell detection and segmentation, human organ segmentation and nano-particle tracking.

In general, applications of computer vision techniques in monitoring biomedical objects include the following stages: detection, segmentation and tracking. Challenges in each stage will potentially lead to unsatisfactory results of automated monitoring. These challenges include different foreground-background contrast, fast motion blur, clutter, object overlap and …

Pointwise And Uniform Convergence Of Fourier Series On Su(2), Donald Forrest Myers

Doctoral Dissertations

"Let f be a Lipschitz function on the special unitary group SU (2). We prove that the Fourier partial sums of f converge to f uniformly on SU (2), thereby extending theorems of Caccioppoli, Mayer, and a special case of Ragozin. Pointwise convergence theorems for the Fourier series of functions on SU (2), due to Liu and Qian, were obtained by Clifford algebra techniques. We obtain similar versions of these theorems using simpler proof techniques: classical harmonic analysis and group theory"--Abstract, page iii.

Dft Investigations Of Hydrogen Storage Materials, Gang Wang

Doctoral Dissertations

"Hydrogen serves as a promising new energy source having no pollution and abundant on earth. However the most difficult problem of applying hydrogen is to store it effectively and safely, which is smartly resolved by attempting to keep hydrogen in some metal hydrides to reach a high hydrogen density in a safe way. There are several promising metal hydrides, the thermodynamic and chemical properties of which are to be investigated in this dissertation.

Sodium alanate (NaAlH₄) is one of the promising metal hydrides with high hydrogen storage capacity around 7.4 wt. % and relatively low decomposition temperature of …

Unconventional Phase Transitions In Random Systems, Hatem Nuri Barghathi

Doctoral Dissertations

"In this thesis we study the effects of different types of disorder and quasiperiodic modulations on quantum, classical and nonequilibrium phase transitions. After a brief introduction, we examine the effect of topological disorder on phase transitions and explain a host of violations of the Harris and Imry-Ma criteria that predict the fate of disordered phase transitions. We identify a class of random and quasiperiodic lattices in which a topological constraint introduces strong anticorrelations leading to modifications of the Harris and Imry-Ma criteria for such lattices. We investigate whether or not the Imry-Ma criterion, that predicts that random field disorder destroys …

Polyacrylamide And Its Derivatives For Oil Recovery, Zun Chen

Doctoral Dissertations

"Polyacrylamide is an umbrella term used to describe the homo-polymer of acrylamide and the copolymer of acrylamide with a small amount of other monomers. Owing to their superior property on increasing viscosity and gelling ability in the presence of crosslinkers, polyacrylamides has become the primarily selection for polymer flooding and gel treatment agent in enhanced oil recovery. Recent developments, performance, applications and limitations of polyacrylamides and its derivatives, including copolymers and hydrogels for enhancing oil recovery are reviewed.

A water-free suspension system was developed to synthesize PAMs and PAMs-microgel. Products are dry particle powder and ready to disperse in water. …

Properties Of Amorphous Transparent Conducting And Semiconducting Oxides From First Principles, Rabi Khanal

Doctoral Dissertations

"Amorphous transparent conducting and semiconducting oxides possess properties superior or comparable to their crystalline counterparts. The structure-property relationship in amorphous oxides is not nearly as well understood as in the case of the crystalline transparent conducting oxides. We have employedab initio molecular dynamics and a liquid quench approach to simulate amorphous oxide structures and performed density functional-based calculations to study the electronic properties of several amorphous conducting and semiconducting oxides with various cation compositions.

The effect of amorphization in oxides was investigated by taking indium oxide as a progenitor of the system. From the thorough study it was confirmed …

Electrodeposition And Characterization Of Metals And Metal Oxides For Energy Conversion And Storage, Ying-Chau Liu

Doctoral Dissertations

"This dissertation investigates the electrodeposition of metal and metal oxide thin films applicable to solar water splitting cells. Paper I describes the synthesis of cobalt hydroxide, ß-Co(OH)₂, by electrochemically reducing tris(ethylenediamine)cobalt(III) in alkaline solution. Paper II presents a scheme to convert the ß-Co(OH)₂ to CoOOH and Co₃O₄ and compares their catalytic activity for the oxygen evolution reaction. Co₃O₄ appears to be a more active catalyst than CoOOH based on Tafel analysis. However, when the observed current densities are corrected for the measured electrochemically active surface area, the linear region of the …

Mineral Complexities As Evidence For Open-System Processes In Formation Of Intermediate Magmas Of The Mount Baker Volcanic Field, Northern Cascade Arc, Ricardo D. (Ricardo Daniel) Escobar-Burciaga

WWU Graduate School Collection

To better understand the complex history of open system differentiation in intermediate subduction zone magmas, complex crystal populations from andesites in the Mount Baker volcanic field (MBVF) in the northern Cascade arc were analyzed. Previous studies have suggested that open-system processes play a dominant role in the petrogenesis of these andesites; however, the studies relied heavily on bulk rock compositions and overlooked complex mineral textures and compositions. This study focuses on establishing mineral and crystal clot populations in four andesite flow units, from which co-crystallizing assemblages were identified. The flow units are the medium-K andesites of Swift Creek (asw …

Fine-Scale Topoclimate Modeling And Climatic Treeline Prediction Of Great Basin Bristlecone Pine (Pinus Longaeva) In The American Southwest, Jamis M. Bruening

WWU Graduate School Collection

Great Basin bristlecone pine (Pinus longaeva) and foxtail pine (Pinus balfouriana) are valuable paleoclimate resources due to the climatic sensitivity of their annually-resolved rings. Recent treeline research has shown that growing season temperatures limit tree growth at and just below the upper treeline. In the Great Basin, the presence of precisely dated remnant wood above modern treeline shows that this ecotone shifts at centennial timescales tracking long-term changes in climate; in some areas during the Holocene climatic optimum treeline was 100 meters higher than at present. Such phenomena has motivated this analysis; regional treeline position models built exclusively from climate …

Exploring The Biofuel Potential Of Isochrysis Sp., John R. Williams Ii

WWU Graduate School Collection

A select few strains of marine microalgae, such as Isochrysis sp., produce high-melting (∼70 °C) lipids known as long-chain alkenones that detrimentally affect biodiesel fuel quality. A method has been developed for the production of an alkenone-free Isochrysis biodiesel. This material was prepared on sufficient scale to allow for extensive analysis according to ASTM standards. Results revealed that while cold flow improved by removal of these high-melting components, a cloud point was still unattainable due to the fuels dark pigment. Further effort in relating the presence of alkenones and the resulting cloud point of the biodiesel, led to decolorization of …

The Effect Of High-Intensity Visible Light On The Bloom Niches Of The Phototrophic Dinoflagellates Alexandrium Fundyense And Heterocapsa Rotundata, Elizabeth C. (Elizabeth Colleen) Cooney

WWU Graduate School Collection

Photosynthetic bloom-forming dinoflagellates heavily influence coastal ecosystems worldwide. Many of these protist algae bloom in surface waters during summer when light intensities are highest. Despite its likely role as a top-down regulator of bloom formation, the consequences of high-intensity sunlight exposure on cells are not well understood. This study sought to reveal the effect of high light exposure on cells, keeping in mind the potential consequences for bloom-formation. The suite of conditions under which a species is best adapted to bloom is referred to here as its “bloom niche”. To investigate, I measured physiological changes deemed relevant to bloom health …

Toward Accurate And Efficient Computational Screening Of The Electronic Structure And Band Gaps Of Semiconductors, Linda Grabill

WWU Graduate School Collection

With increasing population, growing energy demands, and environmental concerns the search for greener energy resources has intensified in recent decades. For example, in the ongoing effort to harness solar energy, researchers have worked to identify and optimize the efficiency of semiconductors beyond traditional silicon photovoltaic materials.

In the development of new materials, synthetic chemists and materials scientists often look to computational chemistry to guide and understand experiments. In the case of semiconductors for solar energy conversion, this includes calculations of electronic band structure and band gap. The most precise computational approaches, such as density functional theory (DFT) are both time …

Spest – A Tool For Specification-Based Testing, Corrigan Redford Johnson

Master's Theses

This thesis presents a tool for SPEcification based teSTing (SPEST). SPEST is designed to use well known practices for automated black-box testing to reduce the burden of testing on developers. The tool uses a simple formal specification language to generate highly-readable unit tests that embody best practices for thorough software testing. Because the specification language used to generate the assertions about the code can be compiled, it can also be used to ensure that documentation describing the code is maintained during development and refactoring.

The utility and effectiveness of SPEST were validated through several exper- iments conducted with students in …