Digital Commons Network^™

Output Feedback Stabilization By Reduced Order Finite Time Observers Using A Trajectory Based Approach, Michael Malisoff, Frederic Mazenc, Saeed Ahmed

Faculty Publications

We use finite time reduced order continuous-discrete observers to solve an output feedback stabilization problem for a class of nonlinear time-varying systems whose outputs contain uncertainty. Unlike earlier works, our feedback is discontinuous, but it does not contain distributed control terms. Our trajectory based approach is based on a contrac-tivity condition. We illustrate our control in the context of a tracking problem for nonholonomic systems in chained form.

On Average Values Of Time-Varying Delays And A New Representation Of Systems With Time-Varying Delays, Frederic Mazenc, Michael Malisoff

Faculty Publications

We show by a counterexample that the asymptotic stability of a system with a pointwise periodic time-varying delay cannot be deduced from the average value of the delay. We use this counterexample to motivate our new representation of systems with time-varying delays, which we use to develop a new state feedback stabilization method.

Sequential Predictors Under Time-Varying Feedback And Measurement Delays And Sampling, Jerome Weston, Michael Malisoff

Faculty Publications

We build sequential predictors for time-varying linear systems with time-varying input delays, outputs, sampling in the control, and time-varying measurement delays. We prove global exponential stability and robustness properties. We allow the sup norm of the input delay to be arbitrarily large and aperiodic sampling. We use a new set of dynamical extensions that contain output measurements, and whose advantages over existing methods include their lack of distributed terms.

High-Harmonic Spectroscopy Of Transient Two-Center Interference Calculated With Time-Dependent Density-Functional Theory, Francois Mauger, Paul M. Abanador, Kenneth Lopata, Kenneth J. Schafer

Faculty Publications

We demonstrate high-harmonic spectroscopy in many-electron molecules using time-dependent density-functional theory. We show that a weak attosecond-pulse-train ionization seed that is properly synchronized with the strong driving mid-infrared laser field can produce experimentally relevant high-harmonic generation (HHG) signals, from which we extract both the spectral amplitude and the target-specific phase (group delay). We also show that further processing of the HHG signal can be used to achieve molecular-frame resolution, i.e., to resolve the contributions from rescattering on different sides of an oriented molecule. In this framework, we investigate transient two-center interference in CO2 and OCS, and how subcycle polarization effects …

Characterizing Diameter Distributions For Uneven-Aged Pine-Oak Mixed Forests In The Qinling Mountains Of China, Shuaichao Sun, Quang V. Cao, Tianjian Cao

Faculty Publications

Pine-oak mixed forests in the Qinling Mountains are an essential part of the ecosystem in Northwestern China. Diameter distribution models for four species groups of pine-oak mixed forests were developed using the Weibull function. Both moment and hybrid estimation approaches were used to predict theWeibull parameters. For each approach, three fitting methods (maximum likelihood estimator regression (MLER), cumulative distribution function regression (CDFR) and modified CDFR) were employed to obtain estimates for coefficients of regression equations to predict Weibull parameters. Overall results indicated that the Moment Estimation approach was better than the Hybrid approach, and that the CDFR method was superior …

Critical Operating Stress Of Persistent Slip Bands In Cu, M. Dodaran, M. M. Khonsari, S. Shao

Faculty Publications

This work elucidates the dependence of operating stress of persistent slip bands (PSB) on the channel width and wall dislocation density. Using Cu as a model system and molecular dynamics as the main investigative tool, a new length scale effect, namely the wall dislocation spacing, is provided to enhance theoretical understanding of PSBs. It is discovered that the operation of PSB is a thermally activated event in which operating stress is inversely related to the wall dislocation spacing, strain rate and temperature. Leveraging the existing framework of confined layer slip in nanoscale metallic multilayers and classical nucleation theory, a mathematical …

Incentive Mechanisms And Impacts Of Negotiation Power And Information Availability In Multi-Relay Cooperative Wireless Networks, Nanmiao Wu, Xiangwei Zhou, Mingxuan Sun

Faculty Publications

Cooperative relaying is highly affected by the way that the source and relays are incentivized. However, the existing studies have not paid enough attention to the impacts of negotiation power and information availability of the players on the network performance. In this paper, two incentive mechanisms for cooperative relaying are first proposed to explore the influence of negotiation power, wherein the source holds either strong or weak negotiation power. In these two cases, the source posts take-it-or-leave-it offers for the relays and has to negotiate possible deals with the relays, respectively. The relay selection rules and the optimal amounts of …

The Impact Of Formal Panhellenic Recruitment On The Development Of Efficacy For Sorority Women, Amanda Jill Horvat

LSU Doctoral Dissertations

Little to no research has been conducted to assess the impact of formal sorority recruitment processes on efficacy levels of sorority women. While numerous studies have been conducted concerning the development of individual women and skills gathered throughout their collegiate experience, there has been limited research on how participation in sorority recruitment may impact psychological and physiological states, and increase or decrease self and collective efficacy.

If the original intent of sororities was to provide friendship, support, and encouragement, are current formal recruitment methods, supported by the National Panhellenic Conference, meeting that goal? Addressing this question requires an in-depth understanding …

Narrow-Band Search For Gravitational Waves From Known Pulsars Using The Second Ligo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, C. Adams, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, G. Allen, A. Allocca, M. A. Aloy, P. A. Altin, A. Amato, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, M. Arène, N. Arnaud

Faculty Publications

Isolated spinning neutron stars, asymmetric with respect to their rotation axis, are expected to be sources of continuous gravitational waves. The most sensitive searches for these sources are based on accurate matched filtering techniques that assume the continuous wave to be phase locked with the pulsar beamed emission. While matched filtering maximizes the search sensitivity, a significant signal-to-noise ratio loss will happen in the case of a mismatch between the assumed and the true signal phase evolution. Narrow-band algorithms allow for a small mismatch in the frequency and spin-down values of the pulsar while coherently integrating the entire dataset. In …

Exploring The Link Between Students’ Usage Of Aleks And Their Performance On State Benchmark Assessments In Mathematics, Verna Marie Richard

LSU Doctoral Dissertations

The purpose of this mixed methods study was to investigate relationships between students’ ALEKS usage, teachers’ implementation of ALEKS, and student performance on the 2017 – 2018 LEAP 2025 mathematics assessment. The quantitative portion of the study involved district-level analyses and teacher-level analyses that explored relationships between students’ ALEKS usage and LEAP performance. The qualitative portion of the study took into consideration previous research findings that have reported associations between program implementation and student achievement. This portion of the study included thematic analyses that examined the following relationships: ALEKS implementation in relation to teacher groups (i.e., RtI 8, Math 8, …

Quantum Cluster Algebras At Roots Of Unity, Poisson-Lie Groups, And Discriminants, Kurt Malcolm Trampel Iii

LSU Doctoral Dissertations

This dissertation studies quantum algebras at roots of unity in regards to cluster structure and Poisson structure. Moreover, quantum cluster algebras at roots of unity are rigorously defined. The discriminants of these algebras are described, in terms of frozen cluster variables for quantum cluster algebras and Poisson primes for specializations of quantum algebras. The discriminant is a useful invariant for representation theoretic and algebraic study, whose laborious computation deters direct evaluation. The discriminants of quantum Schubert cells at roots of unity will be computed from the two distinct approaches. These methods can be applied to many other quantum algebras.

Hourly Precipitation Climatology Of The Southeast United States, Vincent Brown

LSU Doctoral Dissertations

Precipitation changes are one of the most important potential outcomes of a warming climate because of how essential it is to society and ecosystems. Sub-daily precipitation time series provide more information on precipitation characteristics, particularly frequency, intensity, and duration compared to daily data. In a series of four peer-reviewed manuscripts, this research investigates sub-daily precipitation characteristics from a climatological perspective. The first study introduces a climatology of hourly precipitation for four first-order weather stations across Louisiana, explores possible changes in the hourly precipitation distribution, and links winter Gulf of Mexico sea surface temperatures to the frequency of hours with precipitation. …

Improving Power Network Resilience Against Threats, Hamzeh Davarikia

LSU Doctoral Dissertations

The work reported in this dissertation aims at developing a practical tool for utility transmission planners to improve the power network resilience against high-impact, low-frequency events (HILF). Such events rarely happen, but when occurred are catastrophic. In this dissertation, we studied the impact of HILF from the static and dynamic point of view and proposed the planning strategy to lower the devastating effect of the HILF.

In the static analysis, we consider the steady-state situation of the power grids and plan to protect the grid’s components, i.e., generators, buses, and transmission lines, to maximize preserving demand in a disastrous situation. …

Norm Estimates For K-Plane Transforms And Geometric Inequalities, B. Rubin

Faculty Publications

The article is devoted to remarkable interrelation between the norm estimates for k-plane transforms in weighted and unweighted L ^p spaces and geometric integral inequalities for cross-sections of measurable sets in R ⁿ . A similar interrelation is studied for more general j-plane to k-plane transforms on affine Grassmannians and their compact modifications. The article contains a series of new integral-geometric inequalities with sharp constants, explicit equalities, conjectures, and open problems.

Design Of Metamaterials For Optics, Abiti Adili

LSU Doctoral Dissertations

First part of this dissertation studies the problem of designing metamaterial crystals with double negative effective properties for applications in optics by investigating the conditions necessary for generating novel dispersion properties in a metamaterial crystal with subwavelength microstructure. This provides novel optical properties created through local resonances tied to the geometry of the media in subwavelength regime.

In the second part, this dissertation studies the representation formula used to describe band structures in photonic crystals with plasmonic inclusions. By using layer potential techniques, a magnetic dipole operator describing the tangential component of the electrical field generated by magnetic distribution is …

Cogongrass (Imperata Cylindrica (L.) Beauv.) In Louisiana: Cause And Consequence, Lorissa A. Radunzel-Davis

LSU Master's Theses

Cogongrass (Imperata cylindrica (L.) Beauv.), an invasive species from East Asia, is found worldwide and is problematic in several countries. In the United States, it grows primarily in the Southeast, reducing biodiversity by growing in dense patches and potentially causing mortality and reducing value of native and planted pinelands due to a high burning temperature. Using Lee Memorial Forest, a Louisiana State University AgCenter property in Washington Parish as a study site, this thesis explores cogongrass in Louisiana with emphasis on soil microbes and soil legacy effects on native plant species. Cogongrass populations at Lee Memorial Forest were more …

In Vitro Evaluation Of Ovarian Cancer Tumorigenesis As A Function Of Quinone Oxidoreducatse-1 And Cell Phenotype, Milcah S. Jackson

LSU Doctoral Dissertations

In vitro multicellular spheroids are attractive model systems for assessing genetic and epigenetic changes that occur in diseased tissues. Understanding how such alterations in gene and subsequent protein expression affect disease progression and metastasis, drug resistance, and recurrence is of great interest in cancer research. In this regard, examining expression and activity of proteins, such as those with cytoprotective ability that are overexpressed in cancer cells, in addition to cell phenotype (i.e., stem-like, epithelial, mesenchymal, or mixed), are two ways to evaluate genetic and epigenetic changes. Moreover, determining the impact that cytoprotective proteins and cell phenotype have on tumor formation …

Decadal Changes Of Soil Physiochemical Properties In A Freshwater Wetland After Hydrologic Reconnection, Alina Spera

LSU Master's Theses

Sediment, nutrient deprivation and salt water intrusion, among other factors, are driving widespread organic soil collapse and marsh loss in the Mississippi River Delta. Freshwater diversions were designed to reintroduce Mississippi River water and dissolved nutrients into the adjacent basins to manage salinity and slow land loss by maintaining marsh vegetation and nutrient cycling functions. These diversions are controversial by a few, suggesting that nutrient enrichment without a sediment subsidy can lead to further wetland loss in the receiving basins. In this study, a soil characterization is presented for the receiving marsh of the Davis Pond diversion in 2007, just …

Spatiotemporal Impact Of Snow On Underwater Photosynthetically Active Radiation In Taylor Valley, East Antarctica, Madeline E. Myers

LSU Master's Theses

The role of snow on underwater photosynthetically active radiation (UW PAR) in the McMurdo Dry Valleys (MDVs) has been understudied due to lack of a detailed snowfall record. Research has shown that a relationship between snow cover and UW PAR exists, but the extent has never been evaluated in great detail. Although annual snowfall values in the MDVs are low (3 to 50 mm water equivalent annually), trends of increasing snowfall on the continent under future warming conditions could lead to an increased role for snow in regulating UW PAR (and associated primary productivity). Here, I discuss evidence from the …

Matrix Recharge In A Shrink-Swell Floodplain Forest Soil, Savannah R. Morales

LSU Master's Theses

Despite the global distribution of fine-grained Vertisols, the hydrology of these floodplain soils is still not well understood. Vertisols shrink and swell depending on soil moisture leading to a range of soil pore sizes, from large macropore cracks to smaller micropores, and consequently a range of hydraulic conductivities. Despite the plethora of research indicating the importance of both flooding and soil moisture in floodplain ecosystems, the specific role that flooding plays in soil moisture recharge has been less widely studied and remains of interest. Blue food dye and deuterated water were used as tracers to determine the role of the …

Dehn Functions Of Bestvina-Brady Groups, Yu-Chan Chang

LSU Doctoral Dissertations

In this dissertation, we prove that if the flag complex on a finite simplicial graph is a 2-dimensional triangulated disk, then the Dehn function of the associated Bestvina--Brady group depends on the maximal dimension of the simplices in the interior of the flag complex. We also give some examples where the flag complex on a finite simplicial graph is not 2-dimensional, and we establish a lower bound for the Dehn function of the associated Bestvina--Brady group.

Chemosensors Based On Higher Energy Gap Control Of Fluorescence In Conjugated Polymers, Chun-Han Wang

LSU Doctoral Dissertations

Conjugated polymers (CPs) have been widely investigated for their remarkably high sensitivity towards various chemical detection applications. CPs can exhibit effective transduction of certain analyte binding events through changes in fluorescence. These changes include amplified fluorescence quenching ("turn-offmechanism") or an appearance of a fluorescent emission ("turn-onmechanism"). Whereas turn-offsensors can be readily designed and are widely used, amplifying turn-onsensors, from a practical standpoint, are more convenient to use but are more challenging to design.

This dissertation primarily focuses on the development and study of conjugated polymer based amplifying turn-onfluorescence chemosensors utilizing the novel “higher …

Neurostimulator With Waveforms Inspired By Nature For Wearable Electro-Acupuncture, Jose Aquiles Parodi Amaya

LSU Doctoral Dissertations

The work presented here has 3 goals: establish the need for novel neurostimulation waveform solutions through a literature review, develop a neurostimulation pulse generator, and verify the operation of the device for neurostimulation applications.

The literature review discusses the importance of stimulation waveforms on the outcomes of neurostimulation, and proposes new directions for neurostimulation research that would help in improving the reproducibility and comparability between studies.

The pulse generator circuit is then described that generates signals inspired by the shape of excitatory or inhibitory post-synaptic potentials (EPSP, IPSP). The circuit analytical equations are presented, and the effects of the circuit …

Capturing Contingency: Experimental Documentary In The Wake Of Direct Cinema, Dustin Reed Zemel

LSU Doctoral Dissertations

This dissertation examines experimental works in the late 1960s utilizing technologies and techniques connected with direct cinema and cinema vérité models of documentary filming. Focusing on three experimental filmmakers, I show how films by Jonas Mekas, Robert Fulton and William Greaves eschew the austere style associated with observational realism of direct cinema in favor of more ostentatious experimental assembly practices which highlight the role of the filmmaker as artist. I argue for a relational model of assessment in which documentary film’s qualitative renderings of environment become important determinants of documentary integrity and efficacy. With separate chapters focusing on works by …

Graph Information Processing For Artificial Intelligence, Limeng Pu

LSU Doctoral Dissertations

In the last decade, techniques for artificial intelligence (AI) has advanced tremendously, which lead to solutions to many problems that have long-troubled us. Such examples include image/video recognition, speech recognition, and 3D scenario recognition. As the tool become more and more powerful, we started to explore data types that have never been handled in an AI fashion. Graph is undoubtedly the first one that comes to mind. Many important real-life data is or can be represented as graphs or networks: social networks, communication networks, protein-protein interaction networks, molecular structures, etc. Yet very little attention has been devoted to the study …

Using Systematic Prompt Fading To Program A Self-Questioning Strategy With Elementary Students With Disabilities, Leah Michelle Turner

LSU Doctoral Dissertations

Standardized assessments are focused on integrating knowledge from multiple sources and developing composed written responses. This requires the students to be able to read and comprehend on grade level, within the various subject areas (reading, math, science, and social studies), which are skills students with disabilities struggle to do. The purpose of the study was to use a systematic prompt fading procedure as a vehicle to program a self-questioning strategy for students with disabilities. The intervention package occurred in seven phases: baseline, embedded questions training, embedded questions independent practice, self-questioning training, self-questioning independent practice, self-questioning fading, and maintenance. A systematic …

A Study On Large-Scale Deep Learning In Bioinformatics And Biomedical Applications, Shayan Shams

LSU Doctoral Dissertations

Recent advances in Artificial Intelligence and deep learning have provided researchers in various fields insights into the analysis of multiple datasets. These applications include image analysis, text analysis, and many more. However, the effectiveness of deep learning in some areas, such as biomedical imaging and genomic research, has been overshadowed by the variance in the types and complexity of data. This is in addition to the expensive labeling process and the limited size of datasets in these fields. These challenges require advanced deep learning models capable of learning from a small dataset and also from a small number of labeled …

Stray Radiation Dose From X-Ray And Proton Beam Radiation Therapies, Christopher William Schneider

LSU Doctoral Dissertations

The growing population of cancer survivors at risk of radiation induced side-effects is a public health concern. These side-effects include serious conditions such as second cancers, the majority of which occur outside of the primary treatment volume. Radiotherapy treatment planning systems systematically underestimate the dose to tissues out-of-field. Attempts to predict and reduce the risks of radiogenic side effects require accurate and personalized knowledge of the out-of-field radiation dose to patients. The long-term goal of this research is to provide clinical and research tools necessary to reduce the risk of radiotherapy side effects and improve the health outcomes of radiotherapy …

Approaches For Sample Characterization And Lithography With Nanoparticles Using Modes Of Scanning Probe Microscopy, Jayne C. Garno, Temitope O. Jegede, Kathryn B. Mckee, Melissia Porter, Autumn E. Webb, Jin Gyun Lee, Neepa Mk Kuruppu Arachchige, Justin R. Ragains, Noémie Elgrishi

Faculty Publications

Measurement and imaging modes of scanning probe microscopy (SPM) have been routinely applied for characterizing systems of nanoparticles; however the evolution of fabrication methods to prepare arrangements of nanoparticles remains a challenge. Reproducible fabrication of surface structures which integrate nanoparticles within ultra-small patterns will require innovative approaches to achieve high throughput and precision. Strategies for nanoscale lithography have been introduced for preparing defined arrangements of nanoparticles on surfaces based on physical or chemical interactions. For example, physisorption was employed for attaching nanoparticles based on colloidal lithography and site-directed assembly. Microfabricated atomic force microscope (AFM) tips with capillary channels have been …

Rare Earth Geochemistry Of Apatitic Fossils From The Middle-Upper Ordovician Southern Margin Of Laurentia, Rafael Adrian Villanueva

LSU Master's Theses

Widespread deposition of phosphate and a transition from tropical to cool water carbonates is seen throughout Middle-Upper Ordovician Nashville Dome area spanning the M4/M5 sequence boundary. Hypotheses explaining the onset of these lithologic changes have included the onset of glaciation, drawdown of CO₂ related to the Guttenburg Isotope Carbon Excursion (GICE), and siliciclastic weathering, yet none of these studies have provided definitive evidence that shows any of these are the sole factor driving paleoenvironmental changes across the M4/M5 boundary. In order to test whether rapid subsidence along the southeastern margin of Laurentia may have caused an influx of phosphate …