Physical Sciences and Mathematics Commons^™

Kinetics And Mechanisms Of Amine Bis-Phenolate Polymerization Catalysts Featuring Titanium, Zirconium, Or Hafnium Centers, Paul Daniel Pletcher

Open Access Dissertations

The story of Group IV metallocene polymerization catalysts has been a tremendous success in the ability to tune chemical reactivity through structural design. As new, nonmetallocene catalyst systems are being investigated, there has been a lack of quantitative relationships for predicting optimal catalyst design for both desired reactivity and polymeric properties. By utilizing a rational catalyst design strategy that focuses on obtaining a quantitative kinetic analysis of all relevant chemical steps from a family of related catalysts, we have attempted to correlate the fundamental reactivity within the olefin polymerization mechanism to distinctive chemical structures. Such studies have revealed both predictive, …

Coupling Qualitative And Quantitative Analyses Of Pharmaceutical Materials Enabled By Second Harmonic Generation Microscopy, Paul D. Schmitt

Open Access Dissertations

The detection and characterization of crystallinity is critical throughout the drug development process. From the initial establishment of an active pharmaceutical ingredient’s (API) crystal structure to stability testing and quality control, the phase of an API affects the solubility, bioavailability, stability, and efficacy of a drug product. Second harmonic generation (SHG) microscopy has recently been developed as a selective and rapid method for imaging crystallinity in drug formulations. While SHG microscopy can enable the high signal-to-noise (SNR) detection of crystallinity, the intrinsic chemical information content within SHG images is relatively low. In cases of trace crystallinity and/ or small crystal …

Evolutionary Potential Of A Dispersal-Restricted Species In Response To Climate Change, Lorena Torres Martinez

Open Access Dissertations

Habitat replacement and fragmentation associated with projected climate change pose a critical threat to global biodiversity. Edaphically limited plant species with restricted dispersal abilities will be especially handicapped to track their optimal climate spatially. Instead, the persistence of these species will depend on their capacity to adapt in situ to novel climate regimes. Here I evaluated the evolutionary potential of Lasthenia fremontii, an annual plant species restricted to ephemeral wetlands called vernal pools in California to adapt to the projected patterns of climate change. Across L. fremontii distribution there is a latitudinal gradient in precipitation which, combined with reduced …

Data Driven Low-Bandwidth Intelligent Control Of A Jet Engine Combustor, Nathan L. Toner

Open Access Dissertations

This thesis introduces a low-bandwidth control architecture for navigating the input space of an un-modeled combustor system between desired operating conditions while avoiding regions of instability and blow-out. An experimental procedure is discussed for identifying regions of instability and gathering sufficient data to build a data-driven model of the system's operating modes. Regions of instability and blow-out are identified experimentally and a data-driven operating point classifier is designed. This classifier acts as a map of the operating space of the combustor, indicating regions in which the flame is in a "good" or "bad" operating mode. A data-driven predictor is also …

Implementing And Testing A Panel-Based Method For Modeling Acoustic Scattering From Cfd Input, S. Hales Swift

Open Access Dissertations

Exposure of sailors to high levels of noise in the aircraft carrier deck environment is a problem that has serious human and economic consequences. A variety of approaches to quieting exhausting jets from high-performance aircraft are undergoing development. However, testing of noise abatement solutions at full-scale may be prohibitively costly when many possible nozzle treatments are under consideration. A relatively efficient and accurate means of predicting the noise levels resulting from engine-quieting technologies at personnel locations is needed. This is complicated by the need to model both the direct and the scattered sound field in order to determine the resultant …

Packet Filter Performance Monitor (Anti-Ddos Algorithm For Hybrid Topologies), Ibrahim M. Waziri

Open Access Dissertations

DDoS attacks are increasingly becoming a major problem. According to Arbor Networks, the largest DDoS attack reported by a respondent in 2015 was 500 Gbps. Hacker News stated that the largest DDoS attack as of March 2016 was over 600 Gbps, and the attack targeted the entire BBC website.

With this increasing frequency and threat, and the average DDoS attack duration at about 16 hours, we know for certain that DDoS attacks will not be going away anytime soon. Commercial companies are not effectively providing mitigation techniques against these attacks, considering that major corporations face the same challenges. Current security …

Single-Conformation Spectroscopy Of Hydrogen Bonding Networks: Solvation, Synthetic Foldamers, And Neurodegenerative Diseases, Patrick S. Walsh

Open Access Dissertations

The hydrogen bond is one of the most important interactions in natural processes ranging from protein folding to chemical reactions. Two complementary methodologies are applied to understanding this important interaction: top-down and bottom-up. Top-down methods use large molecules, such as proteins, revealing secondary structure information. Bottom-up experiments are performed on small molecules, utilizing high-resolution spectroscopy to reveal underlying quantum mechanical effects. The complexity gap is formed between these two experimental regimes; between large and small molecules; between bulk and individual solvent molecules; between classical mechanics calculations and quantum chemical calculations. This dissertation will focus on the application of gas phase, …

Learning From Data: Plant Breeding Applications Of Machine Learning, Alencar Xavier

Open Access Dissertations

Increasingly, new sources of data are being incorporated into plant breeding pipelines. Enormous amounts of data from field phenomics and genotyping technologies places data mining and analysis into a completely different level that is challenging from practical and theoretical standpoints. Intelligent decision-making relies on our capability of extracting from data useful information that may help us to achieve our goals more efficiently. Many plant breeders, agronomists and geneticists perform analyses without knowing relevant underlying assumptions, strengths or pitfalls of the employed methods. The study endeavors to assess statistical learning properties and plant breeding applications of supervised and unsupervised machine learning …

Ultracold Quantum Scattering In The Presence Of Synthetic Spin-Orbit Coupling, Su-Ju Wang

Open Access Dissertations

Two-body scattering constitutes one of the most fundamental processes in various physical systems ranging from ultracold dilute quantum gases to energetic quark- gluon plasmas. In this dissertation, we study the low-energy atomic collision physics in the presence of synthetic gauge fields, which are generated by atom-light interaction. One category of synthetic gauge fields is the artificial spin-orbit coupling. We discuss three different aspects in scattering theory: ultracold collision, scattering resonance, and bound state formation from a few-body perspective when the atomic spin states are coupled with their center-of-mass motion. The understanding of the spin-orbit effects on the modification of the …

Improving The Eco-System Of Passwords, Weining Yang

Open Access Dissertations

Password-based authentication is perhaps the most widely used method for user authentication. Passwords are both easy to understand and use, and easy to implement. With these advantages, password-based authentication is likely to stay as an important part of security in the foreseeable future. One major weakness of password-based authentication is that many users tend to choose weak passwords that are easy to guess. In this dissertation, we address the challenge and improve the eco-system of passwords in multiple aspects. Firstly, we provide methodologies that help password research. To be more specific, we propose Probability Threshold Graphs, which is superior to …

Quantum Coherence And Entanglement In Open Quantum Systems, Yiteng Zhang

Open Access Dissertations

We humans always want to believe that we can overpower nature. However, the reality is that nature outperforms humans in many aspects. Animals' abilities to navigate/orient and photosynthesis are two excellent examples in these aspects. However, the mechanisms underlying them are still unknown. For decades, scientists and researchers have made a lot of efforts to reveal these mysteries in nature.

Recently, quantum coherence and entanglement are believed to play a crucial role in such biological systems–avian compass and photosynthesis. Thus, nature might know more tricks to utilize quantum mechanics than humans. Studies on the mechanisms underlying avian compass and photosynthesis …

Extreme-Strike And Small-Time Asymptotics For Gaussian Stochastic Volatility Models, Xin Zhang

Open Access Dissertations

Asymptotic behavior of implied volatility is of our interest in this dissertation. For extreme strike, we consider a stochastic volatility asset price model in which the volatility is the absolute value of a continuous Gaussian process with arbitrary prescribed mean and covariance. By exhibiting a Karhunen-Loève expansion for the integrated variance, and using sharp estimates of the density of a general second-chaos variable, we derive asymptotics for the asset price density for large or small values of the variable, and study the wing behavior of the implied volatility in these models. Our main result provides explicit expressions for the first …

The Design And Statistical Analysis Of Single-Cell Rna-Sequencing Experiments, Faye H. Zheng

Open Access Dissertations

Next-generation DNA- and RNA-sequencing (RNA-seq) technologies have expanded rapidly in both throughput and accuracy within the last decade. The momentum continues as emerging techniques become increasingly capable of profiling molecular content at the level of individual cells. One goal of this research is to put forward best practices in the design of single-cell RNA-sequencing (scRNA-seq) experiments, specifically as it relates to choices regarding the trade-off between sequencing depth and sample size. In addition to general guidelines, an interactive tool is presented to aid researchers in making experiment-specific decisions that are informed by real data and practical constraints. Further, a new …

Mathematical Models Of Ebola Virus Disease And Vaccine Preventable Diseases, Yinqiang Zheng

Open Access Dissertations

This thesis focuses on applying mathematical models to studies on the transmission dynamics and control interventions of infectious diseases such as Ebola virus disease and vaccine preventable diseases.

Many models in studies of Ebola transmission are based on the model by Legrand et al. (2007). However, there are potential issues with the Legrand model. First, the model was originally formulated in a complex form, leading to confusion and hindering its uses in practice. To overcome the difficulty, the Legrand model is reformulated in a much simpler but equivalent form in this thesis. The reformulated model also provides an intuitive understanding …

Learning Program Specifications From Sample Runs, He Zhu

Open Access Dissertations

With science fiction of yore being reality recently with self-driving cars, wearable computers and autonomous robots, software reliability is growing increasingly important. A critical pre-requisite to ensure the software that controls such systems is correct is the availability of precise specifications that describe a program's intended behaviors. Generating these specifications manually is a challenging, often unsuccessful, exercise; unfortunately, existing static analysis techniques often produce poor quality specifications that are ineffective in aiding program verification tasks.

In this dissertation, we present a recent line of work on automated synthesis of specifications that overcome many of the deficiencies that plague existing specification …

Role Of River Bathymetry In Hydraulic Modeling Of River Channels, Sayan Dey

Open Access Theses

Accurate geometric representation of the river channel is required for accurate hydraulic modeling of rivers. These are generally obtained through remote sensing techniques such as Light Detection and Ranging (LIDAR). However, these techniques lack the ability to model the submerged channel bed effectively and need to be complemented with surveyed bathymetric data for complete representation of the channel bathymetry, which can be time and cost prohibitive. An alternative to address this issue is to develop conceptual models that can estimate bathymetry.

This study aims to evaluate the potential of a conceptual model, the River Channel Morphology Model (RCMM) which estimates …

Seismic Body-Wave Interferometry Using Noise Autocorrelations For Crustal Structure And A Tutorial On 3d Seismic Processing And Imaging Using Madagascar, Can Oren

Open Access Theses

Seismic body-wave interferometry is applied to selected seismic stations from the USArray Earthscope Transportable Array (TA) by autocorrelating ambient seismic noise recordings to construct effective zero-offset reflection seismograms. The robustness of the auto-correlations of noise traces is first tested on a TA station in Nevada where body-wave reflections similar to those found in an earlier study are identified. This approach is then applied to several TA stations in the central U.S., and the results are compared with synthetic data. Different stacking time periods are then examined to find the shortest time intervals that provide stable correlation stacks.

A tutorial on …

Reactive Flow Modeling Of Small Scale Detonation Failure Experiments For A Baseline Non-Ideal Explosive, David E. Kittell, Nick R. Cummock, Steven F. Son

Purdue Energetics Research Center Articles

Small scale characterization experiments using only 1–5 g of a baseline ammonium nitrate plus fuel oil (ANFO) explosive are discussed and simulated using an ignition and growth reactive flow model. There exists a strong need for the small scale characterization of non-ideal explosives in order to adequately survey the wide parameter space in sample composition, density, and microstructure of these materials. However, it is largely unknown in the scientific community whether any useful or meaningful result may be obtained from detonation failure, and whether a minimum sample size or level of confinement exists for the experiments. In this work, it …

Deep Time Evidence For Climate Sensitivity Increase With Warming, Gary Shaffer, Matthew Huber, Roberto Rondanelli, Jens Olaf Pepke Pedersen

Department of Earth, Atmospheric, and Planetary Sciences Faculty Publications

No abstract provided.

Estimation Of Performance Airspeeds For High-Bypass Turbofans Equipped Transport-Category Airplanes, Nihad E. Daidzic

Journal of Aviation Technology and Engineering

Conventional Mach-independent subsonic drag polar does not replicate the real airplane drag characteristics exactly and especially not in the drag-divergence region due to shock-induced transonic wave drag. High-bypass turbofan thrust is a complicated function of many parameters that eludes accurate predictions for the entire operating envelope and must be experimentally verified. Fuel laws are also complicated functions of many parameters which make optimization and economic analysis difficult and uncertain in the conceptual design phase. Nevertheless, mathematical models and predictions have its important place in aircraft development, design, and optimization. In this work, airspeed-dependent turbofan thrust and the new fuel-law model …

Empirical Research And Practice-Oriented Physics For The Humanities And Sciences, István Berszán

CLCWeb: Comparative Literature and Culture

In his article "Empirical Research and Practice-oriented Physics for the Humanities and Sciences" István Berszán proposes an empirical approach for the humanities and sciences he designates as "practice-oriented physics." He bases his argumentation on Albert-László Barabási's network theory applied and question tenets of complexity, networks, and spaces. Further, Berszán elaborates on the affinity between the spaces of practical orientation and the spaciousness of parallel worlds as explicated in Brian Green's string theory. Berszán posits that because the universe as "symphony" of string oscillations leads to parallel rhythms of happenings and their different spaces of motion and argues that this kind …

Purdue Polytechnic Institute And Project Lead The Way (Pltw), Kevin Kaluf

Purdue P-12 Networking Summit & Poster Session

No abstract provided.

Build Strong Bodies And Minds Through Service Learning, David Sederberg

Purdue P-12 Networking Summit & Poster Session

In Physics and Astronomy at Purdue, service learning is an essential component to our outreach programs. While providing authentic deliverables to the “customer,” service learning engages individuals in ways through which they are able to make meaningful contributions, while at the same time developing their own knowledge and expertise in an area of personal interest or commitment. That learning may involve leadership, instructional design, communication of science fundamentals and applications to K-12 and general audiences, research, reflective practice, and the acquisition of skills that last a lifetime. This presentation illustrates ways in which we leverage resources between service learning and …

Texture Modelling Using Convolutional Neural Networks, Leon A. Gatys, Alexander S. Ecker, Matthias Bethge

MODVIS Workshop

We introduce a new model of natural textures based on the feature spaces of convolutional neural networks optimised for object recognition. Samples from the model are of high perceptual quality demonstrating the generative power of neural networks trained in a purely discriminative fashion. Within the model, textures are represented by the correlations between feature maps in several layers of the network. We show that across layers the texture representations increasingly capture the statistical properties of natural images while making object information more and more explicit. Extending this framework to texture transfer, we introduce A Neural Algorithm of Artistic Style that …

Failure Of Surface Color Cues Under Natural Changes In Lighting, David H. Foster, Iván Marín-Franch

MODVIS Workshop

Color allows us to effortlessly discriminate and identify surfaces and objects by their reflected light. Although the reflected spectrum changes with the illumination spectrum, cone photoreceptor signals can be transformed to give useful cues for surface color. But what happens when both the spectrum and the geometry of the illumination change, as with lighting from the sun and sky? Is it possible, as a matter of principle, to obtain reliable cues by processing cone signals alone? This question was addressed here by estimating the information provided by cone signals from time-lapse hyperspectral radiance images of five outdoor scenes under natural …

Focusing On Selection For Fixation, John K. Tsotsos, Calden Wloka, Yulia Kotseruba

MODVIS Workshop

Building on our presentation at MODVIS 2015, we continue in our quest to discover a functional, computational, explanation of the relationship among visual attention, interpretation of visual stimuli, and eye movements, and how these produce visual behavior. Here, we focus on one component, how selection is accomplished for the next fixation. The popularity of saliency map models drives the inference that this is solved; we suggested otherwise at MODVIS 2015. Here, we provide additional empirical and theoretical arguments. We then develop arguments that a cluster of complementary, conspicuity representations drive selection, modulated by task goals and history, leading to a …

Energy Transfer And Localization In Molecular Crystals, Mitchell A. Wood

Open Access Dissertations

With the aim of developing new technologies for the detection and defeat of energetic materials, this collection of work was focused on using simulations to characterize materials at extremes of temperature, pressure and radiation. Each branch of the work here is collected by which material response is potentially used as the detectable signal.

Where the chemical response is of interest, this work will explore the possibility of non-statistical chemical reactions in condensed-phase energetic materials via reactive molecular dynamics (MD) simulations. We characterize the response of three unique high energy density molecular crystals to different means of energy input: electric fields …

Simulation Of Conservation Practice Effects On Water Quality Under Current And Future Climate Scenarios, Carlington W. Wallace

Open Access Dissertations

Analysis of the effects of implementing different conservation practices, as well as increased levels of conservation practices under existing and projected future climate, will determine if current conservation practice recommendations will be sufficient to maintain soil and water resources. The Soil and Water Assessment Tool (SWAT) was used to study four watersheds of different sizes (CCW = 680 km2, F34 = 183 km2, AXL = 42 km 2 and ALG = 20 km2) located in Northeastern Indiana. The overarching goal of this study was to evaluate the effect of various agricultural practices on runoff and agricultural chemical losses under current …

Information Overload In Structured Data, Pinar Yanardag Delul

Open Access Dissertations

Information overload refers to the difficulty of making decisions caused by too much information. In this dissertation, we address information overload problem in two separate structured domains, namely, graphs and text.

Graph kernels have been proposed as an efficient and theoretically sound approach to compute graph similarity. They decompose graphs into certain sub-structures, such as subtrees, or subgraphs. However, existing graph kernels suffer from a few drawbacks. First, the dimension of the feature space associated with the kernel often grows exponentially as the complexity of sub-structures increase. One immediate consequence of this behavior is that small, non-informative, sub-structures occur more …

Homological Properties Of Determinantal Arrangements, Arnold H. Yim

Open Access Dissertations

We study a certain family of hypersurface arrangements known as determinantal arrangements. Determinantal arrangements are a union of varieties defined by minors of a matrix of indeterminates. In particular, we investigate determinantal arrangements using the 2-minors of a 2 × n generic matrix (which can be thought of as natural extensions of braid arrangements), and prove certain statements about their freeness. We also study the topology of these objects. We construct a fibration for the complement of free determinantal arrangements, and use this fibration to prove statements about their homotopy groups. Furthermore, we show that the Poincaré polynomial of the …