Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Purdue University

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 3001 - 3030 of 8613

Full-Text Articles in Entire DC Network

A Hydroclimatic Assessment Of The U.S. Corn Belt Across Spatial And Temporal Scales, Olivia B. Kellner Apr 2015

A Hydroclimatic Assessment Of The U.S. Corn Belt Across Spatial And Temporal Scales, Olivia B. Kellner

Open Access Dissertations

The term hydroclimate is used to describe the climate of a given location as determined by the incident radiant energy (temperature) and the existence of water in its various forms on Earth. Two types of climate comprise the science of hydroclimatology: the climate as established by general global circulation patterns at specific locations on Earth (large-scale climate) and the climate established at Earth's surface resulting from the daily fluxes of radiant energy and water in its various forms between the atmosphere, Earth's surface, and the subsurface (local-scale climate) (Shelton 2009). This dissertation investigates different spatial and temporal scales of the …

Go to article

Experimental Constraints On Exotic Spin-Dependent Interactions Using Specialized Materials, Rakshya Khatiwada Apr 2015

Experimental Constraints On Exotic Spin-Dependent Interactions Using Specialized Materials, Rakshya Khatiwada

Open Access Dissertations

Various theories predict the possible existence of symmetry violating forces with mesoscopic range interactions from mm-m [1]. These forces can arise from the coupling of a spin 0 boson to spin 1/2 fermions through scalar (gs) and pseudoscalar (gp) couplings. We discuss two experiments that can investigate these interactions using nucleon rich, impressively low magnetic susceptibility (5-100 times lower than pure water) test masses and electron-spin rich, polarized test masses (spin density: 10^20 h/cm3 ). The first experiment looks for a P-odd, T-odd interaction potential proportional to (S.r) where S is the spin of one particle and r is the …

Go to article

The Predictive Power Of The Presences On Cognitive Load, Kadir Kozan Apr 2015

The Predictive Power Of The Presences On Cognitive Load, Kadir Kozan

Open Access Dissertations

The current study had a multi-purpose and complementary research agenda focusing on the predictive power of teaching, cognitive and social presence on intrinsic, extraneous and germane cognitive load. More specifically, this study investigated the predictive relationships between the presences and cognitive load types through multiple regression analyses. This provided insights into the predictive validity of the presences with regard to cognitive load. Five graduate-level fully online courses delivering instruction in the field of learning, design and technology comprised the research context. Data from 103 graduate students were used for multiple regression purposes. Results revealed that (a) the presences can significantly …

Go to article

Polarization-Dependent Nonlinear Optical Microscopy Methods For The Analysis Of Crystals And Biological Tissues, Emma L. Kerian Apr 2015

Polarization-Dependent Nonlinear Optical Microscopy Methods For The Analysis Of Crystals And Biological Tissues, Emma L. Kerian

Open Access Dissertations

The ability to solve a high-resolution protein structure is largely dependent on the successful generation and identification of protein crystals prior to X-ray diffraction (XRD). For novel protein targets, high-throughput crystallography often involves generation of multiple targets and thousands of crystallization trials per target to generate diffraction-quality crystals. Second harmonic generation (SHG) imaging has been developed as a fast, non-destructive and sensitive method for the selective identification of protein crystals, even in highly scattering environments. Polarization-dependent SHG microscopy methods were developed to assess the presence of multidomain crystals to provide a handle on crystal quality. In addition, polarization-dependent two-photon excited …

Go to article

Local Network Coding On Packet Erasure Channels -- From Shannon Capacity To Stability Region, Wei-Cheng Kuo Apr 2015

Local Network Coding On Packet Erasure Channels -- From Shannon Capacity To Stability Region, Wei-Cheng Kuo

Open Access Dissertations

Network Coding (NC) has emerged as a ubiquitous technique of communication networks and has extensive applications in both practical implementations and theoretical developments. While the Avalanche P2P file system from Microsoft, the MORE routing protocol, and the COPE coding architecture from MIT have implemented the idea of NC and exhibited promising performance improvements, a significant part of the success of NC stems from the continuing theoretic development of NC capacity, e.g., the Shannon capacity results for the single-flow multi-cast network and the packet erasure broadcast channel with feedback. However, characterizing the capacity for the practical wireless multi-flow network setting remains …

Go to article

A Pure-Jump Market-Making Model For High-Frequency Trading, Chi Wai Law Apr 2015

A Pure-Jump Market-Making Model For High-Frequency Trading, Chi Wai Law

Open Access Dissertations

We propose a new market-making model which incorporates a number of realistic features relevant for high-frequency trading. In particular, we model the dependency structure of prices and order arrivals with novel self- and cross-exciting point processes. Furthermore, instead of assuming the bid and ask prices can be adjusted continuously by the market maker, we formulate the market maker's decisions as an optimal switching problem. Moreover, the risk of overtrading has been taken into consideration by allowing each order to have different size, and the market maker can make use of market orders, which are treated as impulse control, to get …

Go to article

G-Frobenius Manifolds, Byeongho Lee Apr 2015

G-Frobenius Manifolds, Byeongho Lee

Open Access Dissertations

The goal of this dissertation is to introduce the notion of G-Frobenius manifolds for any finite group G. This work is motivated by the fact that any G-Frobenius algebra yields an ordinary Frobenius algebra by taking its G-invariants. We generalize this on the level of Frobenius manifolds. To define a G-Frobenius manifold as a braided-commutative generalization of the ordinary commutative Frobenius manifold, we develop the theory of G-braided spaces. These are defined as G-graded G-modules with certain braided-commutative "rings of functions", generalizing the commutative rings of power series on ordinary vector spaces. As the genus zero part of any ordinary …

Go to article

Fully Electronic Method Of Measuring Post-Release Gap And Gradient/Residual Stress Of A Mems Cantilever, Andrew Stephen Kovacs Apr 2015

Fully Electronic Method Of Measuring Post-Release Gap And Gradient/Residual Stress Of A Mems Cantilever, Andrew Stephen Kovacs

Open Access Dissertations

Smartphones and other wireless devices have become ubiquitous over the past decade, and the RF front-end inside of them has become more complex and disproportionately consumes more power compared to other components. Micro-electromechanical systems (MEMS) have a huge potential to reduce these problems while simultaneously offering superior performance compared to current leading-edge technology. However, MEMS technology has difficulty transitioning from the lab to large-scale manufacturing due to the unpredictability of device lifetime and manufacturability issues. This can be mitigated by investigating how critical material or physical parameters (gap, stress, Young's modulus, material thickness, etc.) vary from manufacturing uncertainties and how …

Go to article

A Novel In Vivo Tumor Oxygen Profiling Assay: Combining Functional And Molecular Imaging With Multivariate Mathematical Modeling, Chung-Wein Lee Apr 2015

A Novel In Vivo Tumor Oxygen Profiling Assay: Combining Functional And Molecular Imaging With Multivariate Mathematical Modeling, Chung-Wein Lee

Open Access Dissertations

Purpose: The objective of this study is to develop and test a novel high spatio-temporal in vivo assay to quantify tumor oxygenation and hypoxia. The assay implements a biophysical model of oxygen transport to fuse parameters acquired from in vivo functional and molecular imaging modalities. ^ Introduction: Tumor hypoxia plays an important role in carcinogenesis. It triggers pathological angiogenesis to supply more oxygen to the tumor cells and promotes cancer cell metastasis. Preclinical and clinical evidence show that anti-angiogenic treatment is capable of normalizing the tumor vasculature both structurally and functionally. The resulting normalized vasculature provides a more efficient and …

Go to article

Computational Optical Imaging: Applications In Synthetic Aperture Imaging, Phase Retrieval, And Digital Holography, Dennis Joseph Lee Apr 2015

Computational Optical Imaging: Applications In Synthetic Aperture Imaging, Phase Retrieval, And Digital Holography, Dennis Joseph Lee

Open Access Dissertations

Computational imaging has become an important field, as a merger of both algorithms and physical experiments. In the realm of microscopy and optical imaging, an important application is the problem of improving resolution, which is bounded by wavelength and numerical aperture according to the classic diffraction limit. We will investigate the resolution enhancement of phase objects such as transparent biological cells. One key challenge is how to measure phase experimentally. Standard interferometric techniques have the drawback of being sensitive to environmental vibrations and temperature fluctuations, and they use a reference arm which requires more space and cost. Non-holographic methods provide …

Go to article

Large Scale Modeling, Model Reduction And Control Design For A Real-Time Mechatronic System, Qiong Li Apr 2015

Large Scale Modeling, Model Reduction And Control Design For A Real-Time Mechatronic System, Qiong Li

Open Access Dissertations

Mechatronics is the synergistic integration of the techniques from mechanical engineering, electrical engineering and information technology, which influences each other mutually. As a multidisciplinary domain, mechatronics is more than mechanical or electronics, and the mechatronic systems are always composed of a number of subsystems with various controllers. From this point of view, a lot of such systems can be defined as large scale system. The key element of such systems is integration. Modeling of mechatronic system is a very important step in developing control design of such products, so as to simulate and analyze their dynamic responses for control design, …

Go to article

Improvement Of Simulating Bmps And Lid Practices In L-Thia-Lid Model, Yaoze Liu Apr 2015

Improvement Of Simulating Bmps And Lid Practices In L-Thia-Lid Model, Yaoze Liu

Open Access Dissertations

Best management practices (BMPs) and low impact development (LID) practices are popular approaches used to reduce the negative impacts of urbanization on hydrology and water quality. To assist planners and decision-makers in urban development projects, user-friendly tools are needed to assess the effectiveness of BMPs and LID practices on water quantity and quality. To address this need, the Long-Term Hydrologic Impact Assessment-LID (L-THIA-LID) model was enhanced with additional commonly used BMPs and LID practices represented in the model, improved approaches to estimate hydrology and water quality, and representation of practices in series. The tool was used to evaluate the performance …

Go to article

Quantitative Mrna Detection With Advanced Nonlinear Microscopy, Jing Liu Apr 2015

Quantitative Mrna Detection With Advanced Nonlinear Microscopy, Jing Liu

Open Access Dissertations

Cell-specific information on quantity and localization of key mRNA transcripts in single-cell level are critical to the assessment of cancer risk, therapy efficacy, and effective prevention strategies. While current techniques are not capable to visualize single mRNA transcript beyond the diffraction limit. In this thesis, two nonlinear technologies, second harmonic super-resolution microscopy (SHaSM) and transient absorption microscopy (TAM), are developed to detect and quantify single Human edimer receptor 2 (Her2) mRNA transcripts. The SHaSM is used to detect single mRNA transcript beyond the diffraction limit, while the TAM is employed to detect mRNA without the interference of fluorescence background. The …

Go to article

Studies Of The Interaction Of Biogenic Volatile Organic Compounds And Nox In Forest Environments, Kevin M. Mcavey Apr 2015

Studies Of The Interaction Of Biogenic Volatile Organic Compounds And Nox In Forest Environments, Kevin M. Mcavey

Open Access Dissertations

Ozone is a pollutant that causes crop damage, adverse health effects, and is a contributor to global climate change. Ozone concentrations are predicted to rise over the next half-century along with global temperature. Ozone production is controlled by the chemistry between biogenic volatile organic compounds and NOx (NO + NO2), and therefore, a greater understanding of NOx + BVOC chemistry along with their sources and sinks is needed. One large uncertainty in understanding NOx + BVOC chemistry is the production of organic nitrates (RONO2), which act as a radical termination step in the …

Go to article

In Pursuit Of High Resolution Radar Using Pursuit Algorithms, Abdur Rahman Maud Apr 2015

In Pursuit Of High Resolution Radar Using Pursuit Algorithms, Abdur Rahman Maud

Open Access Dissertations

Radar receivers typically employ matched filters designed to maximize signal to noise ratio (SNR) in a single target environment. In a multi-target environment, however, matched filter estimates of target environment often consist of spurious targets because of radar signal sidelobes. As a result, matched filters are not suitable for use in high resolution radars operating in multi-target environments. Assuming a point target model, we show that the radar problem can be formulated as a linear under-determined system with a sparse solution. This suggests that radar can be considered as a sparse signal recovery problem. However, it is shown that the …

Go to article

Algorithms For Bundling And Pricing Trucking Services: Deterministic And Stochastic Approaches, Rodrigo Mesa-Arango Apr 2015

Algorithms For Bundling And Pricing Trucking Services: Deterministic And Stochastic Approaches, Rodrigo Mesa-Arango

Open Access Dissertations

Bundling and pricing trucking services is an important strategic decision for carriers. This is helpful when they consider the incorporation of new businesses to their networks, look for economic and optimal operations, and develop revenue management strategies. Reverse combinatorial auctions for trucking services are real-world examples that illustrate the necessity of such strategies. In these auctions, a shipper asks carriers for quotes to serve combinations of lanes and the carriers have to bundle demand and price it properly. This dissertation explores several dimensions of the problem employing state-of-the-art analytical tools. These dimensions include: Truckload (TL) and less-than-truckload (LTL) operations, behavioral …

Go to article

Spectroscopic Characterization And Photochemistry Of Nitrogen-Containing Molecules Relevant To Titan's Atmosphere, Deepali N. Mehta-Hurt Apr 2015

Spectroscopic Characterization And Photochemistry Of Nitrogen-Containing Molecules Relevant To Titan's Atmosphere, Deepali N. Mehta-Hurt

Open Access Dissertations

Titan's atmospheric chemistry has been the source of intrigue since the planetary body's discovery. Though there is a growing understanding of the atmospheric chemistry of small molecules on Titan, much less is known about larger molecule formation, and particularly about nitrile chemistry. This dissertation characterizes nitrile/isonitrile intermediates that are postulated to be important in Titan's atmosphere, adding to the necessary foundation for understanding Titan's atmospheric chemistry. The vibronic spectroscopy of para-diisocyanobenzene (pDIB, C≡N-Ph-N≡C) has been characterized as a first step towards photochemical studies that can test the transformation of the isonitrile group to other nitrogen-based functionalities.p …

Go to article

The Impact Of Stress History Of Deformable Dry Granules On The Mechanical Properties Of Tablets, Biplob K Mitra Apr 2015

The Impact Of Stress History Of Deformable Dry Granules On The Mechanical Properties Of Tablets, Biplob K Mitra

Open Access Dissertations

A mechanistic understanding of the relationship among the granule composition, individual granule property, downstream robust processing, and the final tablet attributes is critical for rational development of a quality tablet. However, in the dry granulation literature, milled granules that are polydisperse in solid fraction, size, and shape are extensively used for compaction studies. Thus, the effect of an individual granule property or an individual component on the compaction properties of dry granules was not adequately separated. To advance the mechanistic understanding of the effect of dry granulation on tensile strength of tablets, individual granule properties such as size, solid fraction, …

Go to article

An Investigation Into The Phenomenological Relation Between Solar Activity And Nuclear Beta-Decay Rates, Tasneem M. Mohsinally Apr 2015

An Investigation Into The Phenomenological Relation Between Solar Activity And Nuclear Beta-Decay Rates, Tasneem M. Mohsinally

Open Access Dissertations

We investigate experimental evidence for time-varying nuclear decay rates, in contrast to the widely-accepted view that nuclear decaying isotopes disintegrate at a constant rate unaffected by external conditions. We study several past cases of radioactive isotopes exhibiting annual periodicities in their decay rates, presumably related to the annual variation in Earth-Sun distance. Following recent indications of shorter-lived anomalies in 54Mn decay rates concomitant with an X-class flare in 2006, we attempt to design and develop a series of unique signal detection algorithms to identify regions of anomalous activity in a nuclear decay signal. With stringent threshold cut-offs and filtering …

Go to article

The Role Of Employability Skills Training Programs In The Workforce Of Malaysia, Mohd Hazwan Mohd Puad Apr 2015

The Role Of Employability Skills Training Programs In The Workforce Of Malaysia, Mohd Hazwan Mohd Puad

Open Access Dissertations

Employability skills training programs are an essential strategy to improve the skills of the workforce and minimize unemployment in Malaysia. However, there has been a lack of assessment and evaluation studies regarding local employability skills training programs. Existing local studies are focused more on the identification of the skills that allow a person to be employable. Due to the lack of assessment and evaluation studies, stakeholders seem perplexed about the direction of training programs. Therefore, the purpose of this study was to examine the perceptions of educators, employers, and recent graduates regarding the role of employability skills training programs in …

Go to article

Exclusion From Gender Counter-Stereotypic Activities: Proximal And Distal Effects, Megan Kathleen Mccarty Apr 2015

Exclusion From Gender Counter-Stereotypic Activities: Proximal And Distal Effects, Megan Kathleen Mccarty

Open Access Dissertations

The current work explored whether an incidence of exclusion is experienced differently depending on the activity from which one is excluded. Specifically, we investigated whether exclusion from gender stereotypic vs. counter-stereotypic activities affects both how threatening the experience is and beliefs about gender stereotypes. The effects of exclusion activity on need threat and beliefs about gender stereotypes were explored in a series of four studies using multiple methods: participants relived exclusion or inclusion instances from their real lives (Study 1), imagined exclusion or inclusion scenarios (Study 2), were excluded from a virtual ball toss game (Study 3), and were included …

Go to article

The Dynamics Of Ultracold Atoms In Light-Induced Synthetic Gauge Fields, Abraham J. Olson Apr 2015

The Dynamics Of Ultracold Atoms In Light-Induced Synthetic Gauge Fields, Abraham J. Olson

Open Access Dissertations

A central aim of this research is to study the dynamics of ultracold atoms in synthetic gauge fields. In this work, we developed a method to optimize the evaporation of ultracold atoms to the Bose-Einstein condensate (BEC) phase. We implement a model of atomic evaporation in a trapping potential, and we find optimal parameters for the trap depth and stiffness during evaporation. Using this model, we achieve a high efficiency of optical evaporation (γ eff = 4.0).^ Using that BEC, we study the dynamics of the BEC in various light-induced synthetic gauge fields. In particular, we have studied the transition …

Go to article

Experiments With Synthetic Spin-Orbit Coupling And Spin Transport In Bose Einstein Condensates, Robert John Niffenegger Apr 2015

Experiments With Synthetic Spin-Orbit Coupling And Spin Transport In Bose Einstein Condensates, Robert John Niffenegger

Open Access Dissertations

In this thesis I will describe my experiments to study spin transport of spin Bose Einstein Condensates (BECs) with synthetic spin-orbit coupling. First I will describe procedures used to reproduce previous experiments with synthetic gauge fields in Bose-Einstein Condensates, from constant vector potentials to synthetic electric fields and synthetic spin-orbit coupling as well as all of the necessary calibration experiments. Next I will describe new experiments measuring spin transport induced by synthetic spin-dependent electric fields in spin-orbit coupled Bose-Einstein Condensates (BECs). The one dimensional (1D) spin-orbit coupling (SOC) is created with counter propagating Raman lasers which couple hyperfine sub-levels and …

Go to article

Foucault, Kant, Deleuze, And The Problem Of Political Agency, Christopher S. Penfield Apr 2015

Foucault, Kant, Deleuze, And The Problem Of Political Agency, Christopher S. Penfield

Open Access Dissertations

Political agency concerns the transformation of the conditions of social organization through collective action. In order to treat the set of necessary conditions for such agency, I develop a detailed reconstruction of Michel Foucault's political philosophy, placed in relation to the work of Immanuel Kant and Gilles Deleuze. I argue that the key to Foucault's political thought is contained in two crucial but neglected concepts, verticality andtransversality, and that the systematic exposition of these concepts yields an account of what must obtain for political agency to be possible, realizable, and sustainable.

Go to article

The Effect Of Macromolecular Crowding On The Structure Of The Protein Complex Superoxide Dismutase, Ajith Rathnaweera Rajapaksha Mudalige Apr 2015

The Effect Of Macromolecular Crowding On The Structure Of The Protein Complex Superoxide Dismutase, Ajith Rathnaweera Rajapaksha Mudalige

Open Access Dissertations

Biological environments contain between 7 - 40% macromolecules by volume. This reduces the available volume for macromolecules and elevates the osmotic pressure relative to pure water. Consequently, biological macromolecules in their native environments tend to adopt more compact and dehydrated conformations than those in vitro. This effect is referred to as macromolecular crowding and constitutes an important physical difference between native biological environments and the simple solutions in which biomolecules are usually studied.^ We used small angle scattering (SAS) to measure the effects of macromolecular crowding on the size of a protein complex, superoxide dismutase (SOD). Crowding was induced using …

Go to article

Quantification Of Molecular Aggregation Equilibria Using Spectroscopic Measurements And Random Mixing Modeling, Blake M. Rankin Apr 2015

Quantification Of Molecular Aggregation Equilibria Using Spectroscopic Measurements And Random Mixing Modeling, Blake M. Rankin

Open Access Dissertations

Molecular aggregation equilibria, such as the binding of ligands to a central solute molecule, are prevalent throughout biological processes and energy storage devices. However, both the sign and magnitude of hydrophobic and ionic interactions remains a subject of theoretical debate, and has yet to be experimentally determined. Here, Raman vibrational spectroscopy is combined with multivariate curve resolution (Raman-MCR) to experimentally quantify both the number of hydrophobic contacts between alcohol molecules in water and the affinity of ions for molecular hydrophobic interfaces. Furthermore, a generalized theoretical model is developed based on random statistics in which it is assumed that the concentration …

Go to article

Overcoming Uncertainty For Within-Network Relational Machine Learning, Joseph J. Pfeiffer Apr 2015

Overcoming Uncertainty For Within-Network Relational Machine Learning, Joseph J. Pfeiffer

Open Access Dissertations

People increasingly communicate through email and social networks to maintain friendships and conduct business, as well as share online content such as pictures, videos and products. Relational machine learning (RML) utilizes a set of observed attributes and network structure to predict corresponding labels for items; for example, to predict individuals engaged in securities fraud, we can utilize phone calls and workplace information to make joint predictions over the individuals. However, in large scale and partially observed network domains, missing labels and edges can significantly impact standard relational machine learning methods by introducing bias into the learning and inference processes. In …

Go to article

Distributed Real-Time Hybrid Simulation: Modeling, Development And Experimental Validation, Ali Irmak Ozdagli Apr 2015

Distributed Real-Time Hybrid Simulation: Modeling, Development And Experimental Validation, Ali Irmak Ozdagli

Open Access Dissertations

Real-time hybrid simulation (RTHS) has become a recognized methodology for isolating and evaluating performance of critical structural components under potentially catastrophic events such as earthquakes. Although RTHS is efficient in its utilization of equipment and space compared to traditional testing methods such as shake table testing, laboratory resources may not always be available in one location to conduct appropriate large-scale experiments. Consequently, distributed systems, capable of connecting multiple RTHS setups located at numerous geographically distributed facilities through information exchange, become essential. This dissertation focuses on the development, evaluation and validation of a new distributed RTHS (dRTHS) platform enabling integration of …

Go to article

Dynamic Re-Optimization Techniques For Stream Processing Engines And Object Stores, Naresh Kumar Reddy Rapolu Apr 2015

Dynamic Re-Optimization Techniques For Stream Processing Engines And Object Stores, Naresh Kumar Reddy Rapolu

Open Access Dissertations

Large scale data storage and processing systems are strongly motivated by the need to store and analyze massive datasets. The complexity of a large class of these systems is rooted in their distributed nature, extreme scale, need for real-time response, and streaming nature. The use of these systems on multi-tenant, cloud environments with potential resource interference necessitates fine-grained monitoring and control. In this dissertation, we present efficient, dynamic techniques for re-optimizing stream-processing systems and transactional object-storage systems.^ In the context of stream-processing systems, we present VAYU, a per-topology controller. VAYU uses novel methods and protocols for dynamic, network-aware tuple-routing in …

Go to article

On Several Problems Regarding The Application Of Opportunistic Proximate Links In Smartphone Networks, Wei Peng Apr 2015

On Several Problems Regarding The Application Of Opportunistic Proximate Links In Smartphone Networks, Wei Peng

Open Access Dissertations

A defining characteristic of smartphones is the availability of short-range radio transceivers (the proximate channel) such as Bluetooth, NFC, and Wi-Fi Direct, in addition to traditional long-range cellular telecommunication technologies (the cellular channel). Coupled with smartphones' portability and their human users' mobility, the proximate channel provides opportunistic proximate links as a supplement/alternative to the cellular channel's persistent infrastructural links for data communication.^ Opportunistic proximate links have a diverse set of applications, with each application scenario bringing a unique set of often conflicting objectives to balance. This dissertation presents a study on several problems regarding the application of opportunistic proximate links …

Go to article

First Prev Next Last