Digital Commons Network^™

Effect Of Humidity And Testing Strategy On Friction Performance Of Model Brake Pads Containing Nano-Additives, Saikrishna Kancharla

Theses

Interaction of brakes with external environment can considerably influence their performance which could relate to friction instabilities. Humidity can alter the chemistry of friction surfaces that could relate to unwanted phenomena which increase the cost of product. In addition to the chemical phenomena leading to unwanted reactions, there are physical effects related to adsorption of humidity and to modification of adhesion, accompanied with changes in contact surfaces and contact mechanics. The goal of this paper is to address these chemical and physical phenomena occurring at friction interfaces of model friction materials and to relate them to their performance. Friction tests …

Covariance Estimation From Limited Data: State-Of-The-Art, Algorithm Implementation, And Application To Wireless Communications, Ian Tomeo

Theses

There are many different methods of filtering that have been known to provide better results than basic Sample-Matrix-Inversion (SMI). Providing a well-conditioned covariance matrix to these filters will provide a higher Signal to Interference plus Noise Ratio (SINR) than SMI filtering when there are large numbers of receiver element and interference signals. The available number of coherent snapshots that will be used for filter estimation is “not large enough” with respect to the array dimensionality. Common techniques to deal with this situation is to use Krylov or Singular Value Decomposition (SVD) reduced rank filtering. Auxiliary Vector (AV) filtering with the …

Visualizing Resiliency Of Deep Convolutional Network Interpretations For Aerial Imagery, Bhavan Kumar Vasu

Theses

This thesis aims at visualizing deep convolutional neural network interpretations for aerial imagery and understanding how these interpretations change when network weights are damaged. We focus our investigation on networks for aerial imagery, as these may be prone to damages due to harsh operating conditions and are usually inaccessible for regular maintenance once deployed. We simulate damages by zeroing network weights at different levels of the network and analyze their effects on activation maps. Then we re-train the network to observe if it can recover the lost interpretations.

Visualizing changes in the neural network's interpretation, when the undamaged weights are …

Tone Reproduction In Virtual Reality, Antara Mishra

Theses

High dynamic range imaging has become very popular over the years in the field of computer graphics and games. The process of tone reproduction compresses the dynamic range of brightness in a scene to the lower range of display devices, thus making it an essential process in the graphics rendering pipeline. Various tone mapping operators have been tested for static viewing conditions. However, perceptual and temporal adaptation may vary for immersive viewing in a Virtual Reality environment. This thesis implements Ward et al. model (1994), Ward et al. model, Histogram Adjustment (1997) and Irawan, Ferwerda and Marschner model (2005) for …

On Interpixel Capacitive Coupling In Hybridized Hgcdte Arrays: Theory, Characterization And Correction, Kevan Donlon

Theses

Hybridization is a process by which detector arrays and read out circuitry can be independently fabricated and then bonded together, typically using indium bumps. This technique allows for the use of exotic detector materials such as HgCdTe for the desired spectral response while benefiting from established and proven silicon CMOS readout structures. However, the introduction of an intermediate layer composed of conductors (indium) and insulators (epoxy) results in a capacitive interconnect between adjacent pixels.

This interpixel capacitance (IPC) results in charge collected on one pixel, giving rise to a change in voltage on the output node of adjacent pixels. In …

The Photometric Effect Of Macroscopic Surface Roughness On Sediment Surfaces, Greg Badura

Theses

The focus of this work was on explaining the effect of macroscopic surface roughness on the reflected light from a soil surface. These questions extend from deciding how to best describe roughness mathematically, to figuring out how to quantify its effect on the spectral reflectance from a soil’s surface. In this document, I provide a background of the fundamental literature in the fields of remote sensing and computer vision that have been instrumental in my research. I then outline the software and hardware tools that I have developed to quantify roughness. This includes a detailed outline of a custom "LiDAR" …

Semi-Supervised Normalized Embeddings For Fusion And Land-Use Classification Of Multiple View Data, Poppy Immel

Theses

Land-use classification from multiple data sources is an important problem in remote sensing. Data fusion algorithms like Semi-Supervised Manifold Alignment (SSMA) and Manifold Alignment with Schroedinger Eigenmaps (SEMA) use spectral and/or spatial features from multispectral, multimodal imagery to project each data source into a common latent space in which classification can be performed. However, in order for these algorithms to be well-posed, they require an expert user to either directly identify pairwise dissimilarities in the data or to identify class labels for a subset of points from which pairwise dissimilarities can be derived. In this paper, we propose a related …

Resiliency In Deep Convolutional Neural Networks, Faiz Ur Rahman

Theses

The enormous success and popularity of deep convolutional neural networks for object detection has prompted their deployment in various real-world applications. However, their performance in the presence of hardware faults or damage that could occur in the field has not been studied. This thesis explores the resiliency of six popular network architectures for image classification, AlexNet, VGG16, ResNet, GoogleNet, SqueezeNet and YOLO9000, when subjected to various degrees of failures. We introduce failures in a deep network by dropping a percentage of weights at each layer. We then assess the effects of these failures on classification performance. We find the fitness …

Statistical Multi-Way Relationships Of Human Brain Activity, Chen Feng

Theses

The human brain activity is a popular and important topic in the medical science field and academic studies. In recent years, scientists have been applying various statistical methods to analyze human brain activity. Correlation between brain regions is the most common and fundamental method used to perform this task. However, correlation describes only a two-way relationship. This work explores a new approach by analyzing multi-way relationships. Due to computational complexities, we concentrate on three-way relationships. In particular, we compare conventional two-way correlations and three-way regression models. Data transformed and processed from 3,280 MRI scans of the human brain are used …

Classifying Aneugens Using Functional Data Analysis Techniques, Daniel Gremmell

Theses

In the field of genetic toxicology the term aneugen is used to indicate chemical or physical agents that cause chromosomes to malsegregate during division, thereby resulting in altered DNA content in daughter cells. This form of chromosome damage can be detected in certain mammalian cell-based assays, however the molecular mechanism(s) responsible for aneugenic effects are not apparent from these conventional tests. However, the responsible molecular initiating event (MIE) is of interest to pharmaceutical, chemical, and agro-chemical industries, because this knowledge can assist their efforts to design out such liabilities and/or avoid similar chemical structures altogether. This study evaluated the ability …

A Parallelized Implementation Of Cut-And-Solve And A Streamlined Mixed-Integer Linear Programming Model For Finding Genetic Patterns Optimally Associated With Complex Diseases, Michael Yip-Hin Chan

Theses

With the advent of genetic sequencing, there was much hope of finding the inherited elements underlying complex diseases, such as late-onset Alzheimer’s disease (AD), but it has been a challenge to fully uncover the necessary information hidden in the data. A likely contributor to this failure is the fact that the pathogenesis of most complex diseases does not involve single markers working alone, but patterns of genetic markers interacting additively or epistatically. But as we move upwards beyond patterns of size two, it quickly becomes computationally infeasible to examine all combinations in the solution space. A common solution to solving …

The Use Of Bacteriophages To Control Legionella Spp. In Environmental Water Samples, Naama Abdulla Ali Al-Kaabi

Theses

Legionnaires' disease is a potentially fatal form of pneumonia which can affect human, but principally affects those who are susceptible and predisposed to infection due to old age, illness, immunosuppressed and patients at risk. Legionnaires' disease is caused by Gram-negative rod bacteria called Legionella pneumophila. An estimation of 8,000 to 18,000 are actually confirmed cases of Legionnaires' disease per year in the USA. In the UAE, there has been an increase in the number of cases of Legionnaires’ disease which are associated with recent travel to Dubai. Incidents doubled between October 2016 and August 2017. Legionella pneumophila is found …

Lc-Ms/Ms Based Analysis Of Vitamins B3 And B6 In Healthy And Obese Emirati Population, Ghada Rashad Mohamed

Theses

Water-soluble vitamins like Vitamin B3, B6, and B9 are of utmost importance in human health and disease, as they are involved in numerous critical metabolic reactions. Not surprisingly, deficiencies of these vitamins have been linked to various disease states. For example, Vitamin B6 deficiency has been related to many diseases in humans especially in women with type 1 diabetes and in patients with systemic inflammation, liver disease, rheumatoid arthritis, and those infected with HIV. Similarly, derivatives of Vitamin B9 (such as folates), are needed to synthesize, repair, and methylate DNA as well as to act as a cofactor in certain …

Mathematical Modeling Of Corona Virus In The United Arab Emirates, Alya Saif Ahmad Alshehhi

Theses

The Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a viral in-fectious disease that can be transmitted to humans through interaction with infected ani-mals or humans. The Middle East respiratory syndrome (MERS) is still one of the main public health concerns in the Gulf region including United Arab Emirates. The fact that diseases have been imported into other parts of the world show the possibility of has a MERS pandemic. In this work, we are aiming to study a mathematical model of the MERS transmission among the UAE population and camels. The goal is to determine what are the paths of …

A Transparent Square Root Algorithm To Beat Brute Force For Sufficiently Large Primes Of The Form P = 4n + 1, Michael R. Spink

Theses

Finding square roots in the modular integers is a well known problem that is the basis for many modern cryptosystems. For primes of the form p=4n+3, given C\in\mathbb Z_p^\times , finding solutions to x^2\equiv C \pmod{p} is deterministic. For primes of the form p=4n+1, no known deterministic computation exists for determining x given C. Tonelli (later improved by Shanks,) Cipolla, and Pocklington, among others, found sophisticated algorithms to perform this task. Brute force is a transparent approach, but offers no insights into the problem. In this thesis, we produce a transparent approach to this problem, visualized using a model built …

Evolution Of A Common Vector Space Approach To Multi-Modal Problems, Chi Zhang

Theses

A set of methods to address computer vision problems has been developed. Video un- derstanding is an activate area of research in recent years. If one can accurately identify salient objects in a video sequence, these components can be used in information retrieval and scene analysis. This research started with the development of a course-to-fine frame- work to extract salient objects in video sequences. Previous work on image and video frame background modeling involved methods that ranged from simple and efficient to accurate but computationally complex. It will be shown in this research that the novel approach to implement object …

Using Social Media Data In Demand Forecasting: The Case Of Walmart, Aybike Akici

Theses

We describe a fully empirical study on demand forecasting, that is applicable to any real-world data. This is a hands-on case study on the power of social media in demand forecasting. We implement a Box-Jenkins methodology with exogenous variables, namely ARIMAX, to forecast Walmart's future sales. The social media components that we utilize are the number of likes and comments on the official Facebook page of Walmart. The details of the empirical investigation for fitting the best ARIMAX model are presented, and the results are discussed. With this thesis, we demonstrate that social media information should be considered in forecasting, …

The Design And Realization Of A Dual Mode Photoacoustic And Ultrasound Imaging Camera, Zichao Han

Theses

Prostate cancer is currently the second leading cause of cancer death in American men. Diagnosis of the disease is based on persisting elevated prostate-specific antigen (PSA) levels and suspicious lesion felt on digital rectal examination (DRE), prompting transrectal ultrasound (TRUS) imaging guided biopsy. This method, however, has long been criticized for its poor sensitivity in detecting cancerous lesions, leading to the fact that these biopsies generally are not targeted but systematic multi-core in nature that try to sample the entire gland. The thesis presents a new modality that, in combination of ultrasound (US) imaging with multi-wavelength photoacoustic (PA) imaging, improves …

Habitat Preferences Of Blue Marlin (Makaira Nigricans) And Black Marlin (Istiompax Indica) In The Eastern Pacific Ocean, Nima Farchadi, Michael G. Hinton, Andrew R. Thompson, Zhi-Yong Yin

Theses

Overexploitation and climate change can reduce the abundance and shift the spatial distribution of marine species. Determining the habitat suitability of a mobile pelagic species, such as Makaira nigricans (BUM) and Istiompax indica (BLM), can help describe their spatiotemporal distribution patterns over a broad spatial scale, which is a crucial need for fisheries management. Using 14 years (1997-2010) of Inter-American Tropical Tuna Commission (IATTC) catch data from purse-seine vessels in the eastern Pacific Ocean (EPO), we modeled the dynamic habitat suitability of BUM and BLM in response to environmental variables within the EPO using a species distribution model (MaxEnt) with …

Effects Of Slips And Trips On Resultant Lumbar Kinematics, Lumbar Muscle Activity And Low-Back Loads, Kavish J. Kathawala

Theses

Slips, trips, and falls (STFs) represent one of the leading causes of occupational injuries and fatalities. In particular, many prior reports have linked STFs with the onset of low-back disorders, which, depending on the severity of the incident, can leave the worker physically limited both in the workplace and at home. In contrast, the incidence and outcomes of loads acting on the low back due to a slip and trip that does not lead to a fall (i.e., slip/trip without fall: STWF) remain only marginally investigated to date. To address this research deficit, this quantitative study was designed to explore …

The Design, Test And Evaluation Of A Sensing System For Process Analytical Technology (Pat), Trevor Murphy

Theses

Increased globalisation and competitiveness has given rise to a more dynamic and diverse global market that has begun to place incredible strain on manufacturing supply chains. Conventional manufacturing methods such as the batch manufacturing methods employed largely by the materials processing industries i.e. pharmaceuticals, polymers and magnesium processing plants are ill-suited to cope with the demands of today. As products evolve with technological advancements they become more complex to produce and require alternative approaches to manufacturing to ensure product quality while reducing costs and increasing manufacturing efficiencies.

A potential solution to the growing demands on today’s supply chain is process …

The Effects Of Density Gradients On The Distribution And Behavior Of Copepods, Connor Cayson

Theses

Observations of fine-scale behavioral dynamics of zooplankton may shed insight into much larger-scale ecosystem patterns and phenomena. Some zooplankton, such as copepods, are known to aggregate near density gradients; however, it is not clear the extent to which density gradients alone affect copepod distribution and behavior, since these gradients are often associated with phytoplankton layers. In this study, we investigated the behavior of Calanus pacificus in response to salinity gradients through laboratory experiments observed with high-resolution video and analyzed using computational techniques. Image data were collected using two cameras recording continuously for a duration of 30 minutes or more, allowing …

Improvements On Orca For Fast Computation Of Graphlet Degree Vectors Of Any Graphlet Order, Wilberto Z. Nunez

Theses

It is increasingly common to find real-life structures or behaviors represented as graphs in many areas of the computing sciences. Comparing these graphs is a hard task, especially when we are interested in assigning a non-binary similarity score between two large graphs based on some domain-specific context. In bioinformatics, social network analysis and other areas is frequently necessary to compute graph similarities based on the local topological information of each vertex of the given graphs. This is why graphlet degree vectors have become more and more popular in these areas. They provide a simple yet detailed representation of a vertex's …

The Chromatic Villainy Of Complete Multipartite Graphs, Anna Raleigh

Theses

Suppose the colors in a $\chi(G)$-coloring of a graph $G$ have been rearranged. We will call this rearrangement $c^*$.

The chromatic villainy of the $c^*$ is defined as the minimum number of vertices that need to be recolored in order to return $c^*$ to a proper coloring in which each color appears the same number of times as in the initial coloring.

The maximum chromatic villainy when considering all rearrangements of all $\chi(G)$-coloring of $G$ is the chromatic villainy of $G$.

Here, the chromatic villainies of certain families of graphs were investigated and the chromatic villainies of paths and certain …

Using Packet Timing Information In Website Fingerprinting, Mohammad Saidur Rahman

Theses

Website Fingerprinting (WF) enables an eavesdropper to discover what sites the user is visiting despite the use of a VPN or even the Tor anonymity system. Recent WF attacks on Tor have reached high enough accuracy (up to 98%) to prompt Tor to consider adopting defenses based on packet padding. Defenses such as Walkie-Talkie mainly remove features related to bursts of traffic without affecting packet timing. This was reasonable given that previous research on WF attacks ignored or deemphasized the use of packet timing information. In this thesis, we examine the extent to which packet timing can be used to …

Robust Path-Based Image Segmentation Using Superpixel Denoising, Renee T. Meinhold

Theses

Clustering is the important task of partitioning data into groups with similar characteristics, with one category being spectral clustering where data points are represented as vertices of a graph connected by weighted edges signifying similarity based on distance. The longest leg path distance (LLPD) has shown promise when used in spectral clustering, but is sensitive to noisy data, therefore requiring a data denoising procedure to achieve good performance. Previous denoising techniques have involved identifying and removing noisy data points, however this is not a desirable pre-clustering step for data sets with a specific structure like images. The process of partitioning …

A Mathematical Model Of Fluid Flow In Evaporating Droplets Using Wedge Geometry, Jordana O'Brien

Theses

As a droplet of liquid evaporates, particles within the droplet are often pulled to the edge and deposited in a ring-shaped pattern. This is known as the coffee-ring effect. The coffee-ring effect is largely due to evaporation taking place at a pinned contact line. Since this formation is an adverse outcome in many practical applications, methods to counteract the coffee-ring effect have become of interest, including the application of an electric field. In this research project, we discuss the first stage in constructing a coupled mathematical model of colloidal transport within an evaporating droplet under the influence of an electric …

Novel Methods To Determine And Use The Magnetic Vector Potential In Numerical General Relativistic Magnetohydrodynamics, Zachary J. Silberman

Theses

Many codes have been developed to study highly relativistic, magnetized flows around and inside compact objects. Depending on the adopted formalisms, some of these codes evolve the vector potential A, and others evolve the magnetic field B = curl(A) directly. Given that these codes possess unique strengths, it is sometimes desirable to start a simulation using a code that evolves B and complete it using a code that evolves A. Transferring data from one code to another requires an inverse curl algorithm. This dissertation describes two new inverse curl techniques in the context of Cartesian numerical grids: a cell-by-cell method, …

Binary Black Holes In The Inspiral Regime: The Effect Of Spins And Eccentricity On Spacetime Dynamics And Gravitational Radiation, Brennan M. Ireland

Theses

Observations of black hole binaries via the emission of gravitational waves are one of the most exciting discoveries in physics in the past 50 years. The most generic black holes in nature are ones with spin, which may be misaligned with the orbital angular momentum of the binary, and also orbital eccentricity. This demands computationally inexpensive and accurate models of spinning binary black holes for hundreds of orbits as the binary inspirals.

This dissertation is divided into two projects, both of which focus on binary black holes with spin. In the first project, I construct and present a new global, …

Tear Film Model Formulation: A 1-D Exploration, Emily Kiesel

Theses

The study of the tear film of the eye is important for understanding the causes of dye eye syndrome, a disease causing damage to the ocular surface resulting in discomfort for many people. A popular mathematical model describing the evolution of the tear film thickness over time is a fourth-order nonlinear partial differential equation (PDE). This model has been formulated two different ways to facilitate numerical approximations. The first way is just one PDE including a fourth derivative along with the boundary and initial conditions that is solved for the tear film thickness. The second is a system of coupled …