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Electronic Theses and Dissertations

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Articles 2401 - 2430 of 4195

Full-Text Articles in Physical Sciences and Mathematics

Transverse Mode Selection And Brightness Enhancement In Laser Resonators By Means Of Volume Bragg Gratings, Brian Anderson Jan 2015

Transverse Mode Selection And Brightness Enhancement In Laser Resonators By Means Of Volume Bragg Gratings, Brian Anderson

Electronic Theses and Dissertations

The design of high power lasers requires large mode areas to overcome various intensity driven nonlinear effects. Increasing the aperture size within the laser can overcome these effects, but typically result in multi-transverse mode output and reduced beam quality, limiting the brightness of the system. As one possible solution, the angular selectivity of a diffractive optical element is proposed as a spatial filter, allowing for the design of compact high brightness sources not possible with conventional methods of transverse mode selection. This thesis explores the angular selectivity of volume Bragg gratings (VBGs) and their use as spatial transverse mode filters …

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Gauging Training Effectiveness Of Virtual Environment Simulation Based Applications For An Infantry Soldier Training Task, Douglas Maxwell Jan 2015

Gauging Training Effectiveness Of Virtual Environment Simulation Based Applications For An Infantry Soldier Training Task, Douglas Maxwell

Electronic Theses and Dissertations

The U.S. Army Training and Doctrine Command*s Army Learning Concept 2015 and Army Training Concept 2025 are documents that discuss the need for an adaptive soldier learning model with a flexible training delivery methodology. The U.S. Army has been investing in serious gaming technology for the past two decades as a cost effective means to teach tactics and strategy. Today, the U.S. Army is seeking to expand its application of virtual environment training to areas such as cultural awareness and human network analysis for the infantry soldier. These new expanded applications will require a higher level of non-determinant behavior inside …

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Theoretical And Computational Studies Of The Electronic, Structural, Vibrational, And Thermodynamic Properties Of Transition Metal Nanoparticles, Ghazal Shafai Erfani Jan 2015

Theoretical And Computational Studies Of The Electronic, Structural, Vibrational, And Thermodynamic Properties Of Transition Metal Nanoparticles, Ghazal Shafai Erfani

Electronic Theses and Dissertations

The main objective of this dissertation is to provide better understanding of the atomic configurations, electronic structure, vibrational properties, and thermodynamics of transition metal nanoparticles and evaluate the intrinsic (i.e. size and shape) and extrinsic (i.e. ligands, adsorbates, and support) effects on the aforementioned properties through a simulational approach. The presented research provides insight into better understanding of the morphological changes of the nanoparticles that are brought about by the intrinsic factors as well as the extrinsic ones. The preference of certain ligands to stabilize specific sizes of nanoparticles is investigated. The intrinsic and extrinsic effects on the electronic structure …

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Autonomous Quadcopter Videographer, Quiquia Rey Coaguila Jan 2015

Autonomous Quadcopter Videographer, Quiquia Rey Coaguila

Electronic Theses and Dissertations

In recent years, the interest in quadcopters as a robotics platform for autonomous photography has increased. This is due to their small size and mobility, which allow them to reach places that are difficult or even impossible for humans. This thesis focuses on the design of an autonomous quadcopter videographer, i.e. a quadcopter capable of capturing good footage of a specific subject. In order to obtain this footage, the system needs to choose appropriate vantage points and control the quadcopter. Skilled human videographers can easily spot good filming locations where the subject and its actions can be seen clearly in …

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Modeling User Transportation Patterns Using Mobile Devices, Erfan Davami Jan 2015

Modeling User Transportation Patterns Using Mobile Devices, Erfan Davami

Electronic Theses and Dissertations

Participatory sensing frameworks use humans and their computing devices as a large mobile sensing network. Dramatic accessibility and affordability have turned mobile devices (smartphone and tablet computers) into the most popular computational machines in the world, exceeding laptops. By the end of 2013, more than 1.5 billion people on earth will have a smartphone. Increased coverage and higher speeds of cellular networks have given these devices the power to constantly stream large amounts of data. Most mobile devices are equipped with advanced sensors such as GPS, cameras, and microphones. This expansion of smartphone numbers and power has created a sensing …

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Atmospheric Pressure Chemical Vapor Deposition Of Functional Oxide Materials For Crystalline Silicon Solar Cells, Kristopher Davis Jan 2015

Atmospheric Pressure Chemical Vapor Deposition Of Functional Oxide Materials For Crystalline Silicon Solar Cells, Kristopher Davis

Electronic Theses and Dissertations

Functional oxides are versatile materials that can simultaneously enable efficiency gains and cost reductions in crystalline silicon (c-Si) solar cells. In this work, the deposition of functional oxide materials using atmospheric pressure chemical vapor deposition (APCVD) and the integration of these materials into c-Si solar cells are explored. Specifically, thin oxide films and multi-layer film stacks are utilized for the following purposes: (1) to minimize front surface reflectance without increasing parasitic absorption within the anti-reflection coating(s); (2) to maximize internal back reflectance of rear passivated cells, thereby increasing optical absorption of weakly absorbed long wavelength photons (? > 900 nm); (3) …

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White Light Continuum For Broadband Nonlinear Spectroscopy, Trenton Ensley Jan 2015

White Light Continuum For Broadband Nonlinear Spectroscopy, Trenton Ensley

Electronic Theses and Dissertations

Supercontinuum (SC) generation, oftentimes referred to as white-light continuum (WLC), has been a subject of interest for more than 40 years. From the first observation of WLC in condensed media in the early 1970s to the first observation of WLC in gases in the mid-1980s, much work has been devoted to developing a framework for understanding the complex nature of this phenomenon as well as discovering its utility in various applications. The main effort of this dissertation is to develop a WLC for the purpose of broadband nonlinear spectroscopy and use it in spectroscopic measurements. The ability to generate a …

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Modeling The Impact Of Future Climate On Drainage Infrastructures, Tyler J. Baumbach Jan 2015

Modeling The Impact Of Future Climate On Drainage Infrastructures, Tyler J. Baumbach

Electronic Theses and Dissertations

Research has shown a potential 20% increase in future heavy and extreme precipitation events over the Midwestern States. Drainage infrastructures designed using current design conditions may not be able to convey projected runoffs resulting in flooding and damage to infrastructure. The objective of this paper is to determine the effects of future climate variability on culvert selections in a southwest South Dakota watershed. The scope of the study was defined through a comprehensive literature review. Future climate events were based on a 20% increase in current annual precipitation over the Upper White River Subbasin Watershed. A portion of the White …

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The Effects Of Chanellization And Channel Restoration On Aquatic Habitat And Biota Of The Pecos River, New Mexico, Darrel J. Mecham Jan 2015

The Effects Of Chanellization And Channel Restoration On Aquatic Habitat And Biota Of The Pecos River, New Mexico, Darrel J. Mecham

Electronic Theses and Dissertations

River channelization has been shown to negatively impact riverine ecosystems by degrading aquatic habitat conditions, decreasing diversity of both fish and aquatic invertebrate assemblages and impairing fish recruitment. As knowledge of the negative impacts of channelization has increased, so have channel restoration efforts. We evaluated a recent channel restoration project on the Pecos River, New Mexico by comparing abiotic and biotic conditions among five reaches of river, including the restored reach, an unchannelized reach and a channelized reach all prone to streamflow intermittence and an unchannelized reach and channelized reach more perennial in nature. Our first objective was to assess …

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Drivers Of Agricultural Land Use Change And Management Decisions In The Dakotas: The Influence Of Climate Change And Other Factors, Moses Luri Jan 2015

Drivers Of Agricultural Land Use Change And Management Decisions In The Dakotas: The Influence Of Climate Change And Other Factors, Moses Luri

Electronic Theses and Dissertations

This thesis conducts a general assessment of the: main drivers of land use change; recent and projected land use patterns; and the evolution of agriculture in the Dakotas. Specifically, it determines the main motives of land use change in the Dakotas by investigating individual and joint effects of external drivers of land use change on farm operators’ decisions and also examines recent and projected agricultural land use patterns in the Dakotas. Farm operators’ perceptions about the evolution of agriculture in the Dakotas based on observed changes in their local area were also analyzed. The study region consists of 37 counties …

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Efficient Utilization Of Solar Energy In Dye-Sensitized Solar Cells And In The Photocatalytic Reduction Of Carbon Dioxide, Aron Joel Huckaba Jan 2015

Efficient Utilization Of Solar Energy In Dye-Sensitized Solar Cells And In The Photocatalytic Reduction Of Carbon Dioxide, Aron Joel Huckaba

Electronic Theses and Dissertations

One of the most important questions humanity will face in the next 100 years is going to be "What will happen when oil runs out?" This dissertation describes efforts to utilize solar energy to improve renewable energy technology in two ways: First, through the improvement of dye sensitized solar cells by theimprovement of D-π-A dye subunits, the development of practical sensitizers, and progress towards stable, tunable redox shuttles. A novel indolizine donor subunit was synthesized that was shown to be the strongest reported donor. Dyes made from this novel donor and devices using the Γ-/I 3- reached up to 5.4% …

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Gold Nanomolecules : Developing Synthetic Protocols, Characterization And Investigation Of Ligand Effects On Structure And Properties, Praneeth Reddy Nimmala Jan 2015

Gold Nanomolecules : Developing Synthetic Protocols, Characterization And Investigation Of Ligand Effects On Structure And Properties, Praneeth Reddy Nimmala

Electronic Theses and Dissertations

The term "Nano" in chemistry refers to particles/molecules in the size range 1 to 100 nm. Gold nanoparticles were used in ancient times in making decorative glass as they produce vibrant, size dependent, colors upon interaction with light. Gold is a preferred choice of metal for the synthesis of nanoparticles mainly due to its inertness to atmospheric conditions and most chemicals. Gold thiolate nanomolecules, which is the primary focus of this dissertation research, are chemical molecules with a fixed number of gold atoms and organo-thiolate ligands. They are of the form Aux(SR)y and possess molecule-like properties as a result of …

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The Spectroscopic Characterization Of Newly Developed Emissive Materials And The Effects Of Environment On Their Photophysical Properties, Louis Edward Mcnamara Jan 2015

The Spectroscopic Characterization Of Newly Developed Emissive Materials And The Effects Of Environment On Their Photophysical Properties, Louis Edward Mcnamara

Electronic Theses and Dissertations

The development of new materials capable of efficient charge transfer and energy storage has become increasingly important in many areas of modern chemical research. This is especially true for the development of emissive optoelectronic devices and in the field of solar to electric energy conversion. The characterization of the photophysical properties of new molecular systems for these applications has become critical in the design and development of these materials. Many molecular building blocks have been developed and understanding the properties of these molecules at a fundamental level is essential for their successful implementation and future engineering. This dissertation focuses on …

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Functional Reactive Programming For Games, Peter Adewunmi Salu Jan 2015

Functional Reactive Programming For Games, Peter Adewunmi Salu

Electronic Theses and Dissertations

We investigate the effectiveness of functional reactive programming for games. To accomplish this, we clone aa, an existing game, in Elm, a purely functional programming language. We find that functional reactive programming offers an excellent alternative to event driven programming in purely functional languages. Elm still needs more work if it aims to compete with JavaScript libraries. Games, which typically need several inputs at the same time, benefit from the first class status of Signals, which allow them to be combined.

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Mercury Methylation Potentials In Sediments An Ancient Cypress Wetland Using Species-Specific Isotope Dilution-Gc-Icp-Ms: Analytical Method Development And The Effect Of Sorbent Amendments, Derek Davin Bussan Jan 2015

Mercury Methylation Potentials In Sediments An Ancient Cypress Wetland Using Species-Specific Isotope Dilution-Gc-Icp-Ms: Analytical Method Development And The Effect Of Sorbent Amendments, Derek Davin Bussan

Electronic Theses and Dissertations

A novel method was developed to measure mercury (Hg) directly in environmental solids using inductively coupled plasma mass spectrometry (ICP-MS) with online sample ashing. The method combines a direct mercury analyzer (DMA) that is based on sample combustion, Hg pre-concentration by amalgamation with gold, and atomic absorption spectrometry (AAS), with a high resolution ICP-MS. Unlike AAS, the ICP-MS is capable of individual isotope measurements allowing for accurate quantitation by isotope dilution mass spectrometry (IDMS) and for isotope tracer experiments. The method was validated using certified reference materials including sediment (NIST 2709), leaves (NIST 1547), and fish-muscle (DORM-3), with recoveries within …

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Exploration Of Novel Synthetic Utility Of Lithioacetonitirile, Rambabu Sankranti Jan 2015

Exploration Of Novel Synthetic Utility Of Lithioacetonitirile, Rambabu Sankranti

Electronic Theses and Dissertations

No abstract provided.

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Specification And Mechanical Verification Of Performance Profiles Of Software Components, Nighat Yasmin Jan 2015

Specification And Mechanical Verification Of Performance Profiles Of Software Components, Nighat Yasmin

Electronic Theses and Dissertations

Software performance predictability is vital to a system design and unpredictable performance is a leading cause of software failure. The emphasis of this dissertation is on verification that component-based software performs as specified. Performance profiles (specifications) depend on functional specifications and are necessary for all components for modular verification. Modular verification process is scalable because it uses profiles as contracts and allows verification of a single component in isolation with the assumption that any underlying component would have already been verified or will be verified to meet its specifications independently. This dissertation presents an integration of performance specification (profiles) with …

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Identifying A Mechanism For An Infiltration Threshold From The Sunflower River, Ms To The Underlying Alluvial Aquifer, Austin Cole Patton Jan 2015

Identifying A Mechanism For An Infiltration Threshold From The Sunflower River, Ms To The Underlying Alluvial Aquifer, Austin Cole Patton

Electronic Theses and Dissertations

Long-term groundwater level and stream stage measurements at a USGS coupled groundwater stream-gaging station located on the Sunflower River in Sunflower, MS show an apparent stage-threshold for infiltration to the underlying alluvial aquifer. This site is located near the center of a large regional groundwater cone of depression in the Mississippi River Valley alluvial aquifer. The USGS well (termed well 3 in this study) was thought to be completed in the regional shallow aquifer, though often recording anomalously high water levels relative to other wells in the region. The purpose of this research was to identify the responsible mechanism for …

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The Least Prime Number That Splits Completely In S3-Sextic Number Fields, Zhenchao Ge Jan 2015

The Least Prime Number That Splits Completely In S3-Sextic Number Fields, Zhenchao Ge

Electronic Theses and Dissertations

In number theory, an integer n is quadratic residue modulo an odd prime p if n is congruent to a perfect square modulo p. Otherwise, n is is called a quadratic nonresidue. Bounding the least prime quadratic residue and the least quadratic nonresidue are two very classical problems in number theory. These classical problems can be generalized to any number field K by asking for bounds the least for prime that splits completely or does not split completely, respectively, in the ring of integers of K. The goal of this thesis is to bound the least prime that splits completely …

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Progress Toward The Total Synthesis Of The Natural Product Herbicide Ascaulitoxin Aglycone, Jeffery Brian Morgan Jan 2015

Progress Toward The Total Synthesis Of The Natural Product Herbicide Ascaulitoxin Aglycone, Jeffery Brian Morgan

Electronic Theses and Dissertations

Ascaulitoxin aglycone is a structurally unique bis-amino acid isolated from the fungal species Ascochyta caulina, with herbicidal activity against Chenopodium album. Ascaulitoxin aglycone's potent herbicidal activity coupled with an unknown but novel mechanism of action makes it a perfect candidate for further study in the pursuit of new natural product herbicides. This dissertation research will illustrate three synthetic strategies towards the total synthesis of ascaulitoxin aglycone from chiral pool building blocks. Strategy 1 invokes the use of the Henry reaction as a key step for the construction of the central C4-C5 cis-aminohydroxy group, which was moderately successful, but abandoned in …

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Biomolecular Folding Rates As Understood From Single-Reaction-Coordinate Langevin Dynamics And Kramers’ Theory, Md Adnan Kabir Jan 2015

Biomolecular Folding Rates As Understood From Single-Reaction-Coordinate Langevin Dynamics And Kramers’ Theory, Md Adnan Kabir

Electronic Theses and Dissertations

Langevin dynamics was used to model the folding and unfolding of simple, hairpin-like biomolecules whose ends are attached to laser-trapped beads, as occurs in optical tweezers experiments. The Langevin process was evolved numerically, using parameters motivated by real experimental systems. Folding trajectories were generated and analyzed to extract the folding rate as a function of the force applied to the beads. The observed rate was compared to the analytical predictions of Kramers' theory. Strong discrepancies were noted. The failure of the Kramers' theory was attributed to the slow dynamical response of the beads, which it does not account for. The …

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Effect Of Accelerated Global Expansion On Bending Of Light, Mir Emad Aghili Jan 2015

Effect Of Accelerated Global Expansion On Bending Of Light, Mir Emad Aghili

Electronic Theses and Dissertations

No abstract provided.

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Effective Tuning Of Bimetallic Composition Of Gold-Copper Nanomolecules And The Emergence Of Plasmon-Like Feature In Optical Spectra, Asantha Champika Dharmaratne Jan 2015

Effective Tuning Of Bimetallic Composition Of Gold-Copper Nanomolecules And The Emergence Of Plasmon-Like Feature In Optical Spectra, Asantha Champika Dharmaratne

Electronic Theses and Dissertations

Au144-xCux(SR)60 alloy nanomolecules were synthesized and characterized by using ESI-MS to atomic precision. A maximum of 23 copper atoms replace the gold atoms; when the number of copper atoms is higher than eight, a surface plasmon-like peak appears at ∼520 nm. Based on the fundamental, elemental properties of Au and Cu, we predict a mixed atomic ordering and incorporation into the Au12 and Au 42 shells of the proposed icosahedral structured model. Alloy nanomolecules reported here could have potential applications in the field of catalysis and optical sensors.

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Method Development For Mass Spectrometric Characterization Of Ultra-Small Nanomolecules And Mass Spectrometry Imaging Of Selected Biomolecules, Nuwan K. Kothalawala Jan 2015

Method Development For Mass Spectrometric Characterization Of Ultra-Small Nanomolecules And Mass Spectrometry Imaging Of Selected Biomolecules, Nuwan K. Kothalawala

Electronic Theses and Dissertations

High sensitivity, selectivity and remarkable identification capabilities facilitate the applicability of mass spectrometry (MS) in diverse fields. This dissertation outlines how this cutting edge technology is used to determine the chemical composition of the ultra-small nanomolecules (NMs) to atomic precision and obtain spatial resolution of selected biomolecules using mass spectrometry imaging (MSI). Chapter I includes introduction to electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) MS used in my PhD research. Chapter II explains how high resolution ESI-MS methods were developed to analyze the polar water-soluble NMs. These new methods express how ESI-MS parameters need to be optimized …

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Fscan Code Development For Advanced Ligo Detector Characterization, Cody Arceneaux Jan 2015

Fscan Code Development For Advanced Ligo Detector Characterization, Cody Arceneaux

Electronic Theses and Dissertations

The Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) is an experiment designed to provide direct detection of gravitational waves. Its searches for periodic gravitational waves are highly susceptible to long-duration noise that appears as spectral lines. FScan is a tool for finding spectral lines and is used to identify the lines that appear in the gravitational-wave data; it is also used to characterize LIGO's detectors. This thesis details work in rewriting the plotting portion of FScan, making improvements to the FScan driver script, and writing code to assist in the tracking of wandering spectral lines. In particular, this thesis presents the …

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Testing Lepton Nonuniversality In Tau Neutrino Scattering, Hongkai Liu Jan 2015

Testing Lepton Nonuniversality In Tau Neutrino Scattering, Hongkai Liu

Electronic Theses and Dissertations

Recently hints of lepton flavor non-universality emerged in the BaBar and LHCb experiments. In this paper we propose tests of lepton universality in scattering. To parametrize the new physics we adopt an effective Lagrangian approach and consider the neutrino deep inelastic scattering processes tau neutrino+nucleon to tau + X and muon neutrino+nucleon to muon + X where we assume the largest new physics effects are in the tau sector. We also consider an explicit leptoquark model in our calculations. In order to make comparison with the standard model and also in order to cancel out the uncertainty of the parton …

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Accurate Computation Of Molecular Properties From Novel Applications Of Quantum Mechanical Wavefunction Methods, James Coleman Howard Jan 2015

Accurate Computation Of Molecular Properties From Novel Applications Of Quantum Mechanical Wavefunction Methods, James Coleman Howard

Electronic Theses and Dissertations

High-accuracy quantum mechanical (qm) wavefunction methods have been applied to compute molecular properties of weakly-bound clusters. This work focuses on both extending the applicability of robust theoretical methods to larger systems and also determining the inherent accuracy of ab initio methods when compared to experimentally measured properties. Described here is the development of an efficient many-body approach that offers the ability to reduce both the time and the computational resources normally required to compute these properties reliably. The n-body:many-body qm:qm technique has been extended to compute harmonic vibrational frequencies of clusters. Applying this methodology to small hydrogen-bonded clusters demonstrates that …

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Design And Implementation Of Fast Motion Estimation In Modern Video Compression On Gpu, Zhaohua Yi Jan 2015

Design And Implementation Of Fast Motion Estimation In Modern Video Compression On Gpu, Zhaohua Yi

Electronic Theses and Dissertations

Motion estimation is the most compute expensive part of high definition video compression. It accounts for more than 50\% of overall execution. Therefore, improving the performance of motion estimation can make significant impact on the overall performance of video compression. The performance of motion estimation can be improved in two aspects: algorithm and implementation. This thesis touches both aspects. We first propose an innovative motion estimation algorithm by replacing the traditional block matching method which comparing blocks pixel by pixel with a brand new method which based on lbp (local binary pattern) code. Our new method first encodes the original …

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Microtremor Recordings In Northern Mississippi: Evaluating Site Effect And Correlating With Wave Climate, Zhen Guo Jan 2015

Microtremor Recordings In Northern Mississippi: Evaluating Site Effect And Correlating With Wave Climate, Zhen Guo

Electronic Theses and Dissertations

Site effects is considered as one of the main reasons that cause enormous damages in earthquakes and it is mainly controlled by the local geological condition. The main research area, Northern Mississippi, is located in Mississippi Embayment (ME) where is mainly composed of unconsolidated sediments which can be as thick as 1400m along the Mississippi River floodplain, and is favorable to have significant site effects. Meanwhile Northern Mississippi is also located in the moderate to heavy potential damage area of the New Madrid Seismic Zone, which is in the northern section of ME. Therefore, it is very necessary to evaluate …

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Gini Covariance Matrix And Its Affine Equivariant Version, Lauren Anne Weatherall Jan 2015

Gini Covariance Matrix And Its Affine Equivariant Version, Lauren Anne Weatherall

Electronic Theses and Dissertations

Gini's mean difference (GMD) and its derivatives such as Gini index have been widely used as alternative measures of variability over one century in many research fields especially in finance, economics and social welfare. In this dissertation, we generalize the univariate GMD to the multivariate case and propose a new covariance matrix so called the Gini covariance matrix (GCM). The extension is natural, which is based on the covariance representation of GMD with the notion of multivariate spatial rank function. In order to gain the affine equivariance property for GCM, we utilize the transformation-retransformation (TR) technique and obtain TR version …

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