Physical Sciences and Mathematics Commons^™

Robust Control Methods For Nonlinear Systems With Uncertain Dynamics And Unknown Control Direction, Chau T. Ton

Doctoral Dissertations and Master's Theses

Robust nonlinear control design strategies using sliding mode control (SMC) and integral SMC (ISMC) are developed, which are capable of achieving reliable and accurate tracking control for systems containing dynamic uncertainty, unmodeled disturbances, and actuator anomalies that result in an unknown and time-varying control direction. In order to ease readability of this dissertation, detailed explanations of the relevant mathematical tools is provided, including stability denitions, Lyapunov-based stability analysis methods, SMC and ISMC fundamentals, and other basic nonlinear control tools. The contributions of the dissertation are three novel control algorithms for three different classes of nonlinear systems: single-input multiple output (SIMO) …

Nonlinear Control For Dual Quaternion Systems, William D. Price

Doctoral Dissertations and Master's Theses

The motion of rigid bodies includes three degrees of freedom (DOF) for rotation, generally referred to as roll, pitch and yaw, and 3 DOF for translation, generally described as motion along the x, y and z axis, for a total of 6 DOF. Many complex mechanical systems exhibit this type of motion, with constraints, such as complex humanoid robotic systems, multiple ground vehicles, unmanned aerial vehicles (UAVs), multiple spacecraft vehicles, and even quantum mechanical systems. These motions historically have been analyzed independently, with separate control algorithms being developed for rotation and translation. The goal of this research is to study …

Researching Critical Incidents Of Transformation, Paul R. Scheele

Antioch University Dissertations & Theses

This study examined transformation within individuals in a collaborative adult learning context. Using a combination of methods—surveys and critical incident technique (CIT)—the study explored in depth the experiences of 28 subjects from a population of 100 participants in an open-enrollment workshop, the Awakening the Dreamer, Changing the Dream Symposium produced by the Pachamama Alliance. The program employs high-impact training approaches to inform participants about social injustices and environmental practices that threaten the planet, and to encourage them to act on that information. The research focused on critical incidents at or shortly after the workshop that produced significant and meaningful change …

Voltage Modulated Infrared Reflectance Study Of Soluble Organic Semiconductors In Thin Film Transistors, Emily Geraldine Bittle

Theses and Dissertations--Physics and Astronomy

Soluble organic semiconductors have attracted interest due to their potential in making flexible and cheap electronics. Though their use is being implemented in electronics today, the conduction mechanism is still under investigation. In order to study the charge transport, this study examines the position, voltage, and frequency dependence of charge induced changes in far infrared absorption in soluble organic semiconductors in thin-film transistor structures. Measurements are compared to a simple model of a one-dimensional conductor which gives insight into the charge distribution and timing in devices. Main results of the study are dynamic measurements of charge taken by varying the …

Initiation And Continuation Of Randomized Trials After The Publication Of A Trial Stopped Early For Benefit Asking The Same Study Question: Stopit-3 Study Design, Gabriela J. Prutsky, Juan Domecq, Patricia J. Erwin, Matthias Briel, Victor M. Montori, Elie A. Akl, Joerg J. Meerpohl, Dirk Bassler, Stefan Schandelmaier, Stephen D. Walter, Qi Zhou, Pablo Coello, Lorenzo Moja, Martin Walter, Kristian Thorlund, Paul Glasziou, Regina Kunz, Ignacio Ferreira-Gonzalez, Jason Busse, Xin Sun, Annette Kristiansen, Benjamin Kasenda, Osama Qasim-Agha, Gennaro Pagano, Hector Pardo-Hernandez, Gerard Urrutia, Mohammad Murad, Gordon Guyatt

Wayne State University Associated BioMed Central Scholarship

Abstract

Background

Randomized control trials (RCTs) stopped early for benefit (truncated RCTs) are increasingly common and, on average, overestimate the relative magnitude of benefit by approximately 30%. Investigators stop trials early when they consider it is no longer ethical to enroll patients in a control group. The goal of this systematic review is to determine how investigators of ongoing or planned RCTs respond to the publication of a truncated RCT addressing a similar question.

Methods/design

We will conduct systematic reviews to update the searches of 210 truncated RCTs to identify similar trials ongoing at the time of publication, or started …

Meat-Wise Eating Habits, J. Haycock, K. Anderson, Roslynn Brain

Environment and Society Faculty Publications

Whether from a cow, pig, bird, fish, or other domestic or game animal, meat is universally enjoyed as part of the cultural culinary experience. It is also an excellent source of protein, which is important for a healthy body. Many people who eat meat, however, are not aware of the impact their consumption has on the environment. This guide provides a set of quick facts and action tools to make wiser choices concerning meat consumption.

Designing Your Home For Maximum Natural Lighting, P. Bytheway, Roslynn Brain

Environment and Society Faculty Publications

There are many benefits to having more natural light in your home. The most obvious of these are the savings you can achieve with a reduced utility bill. According to the U.S. Department of Energy (2012), about 10% of household electricity usage comes from lighting. The more natural light you have in your house, the less lights you have to turn on, and the less electricity you use. Another benefit, also related to energy use, is natural light can help heat homes. One of the best reasons to design your home for natural light involves the health benefits gained through …

Easy Steps To Reduce Your Energy Bill, B. Thomas, Brett Tingey, Roslynn Brain

Environment and Society Faculty Publications

Fossil fuels supply most of Utah’s energy needs. Any process using fossil fuels, however, emits carbon dioxide (CO2), mercury, and oftentimes other contaminants that stress Utah’s beautiful natural resources (Dresselhaus & Thomas, 2001). Most electricity in Utah is fueled by coal-fired power, which adds mercury to our air and waterways. Increased mercury in ducks and fish have resulted in restrictions for Utah family pastimes, such as fishing and duck hunting. In 2010, 23% of energy consumption in the United States was residential, totaling 22.2 quadrillion Btu (EIA, 2010). A quadrillion Btu is about equal to the amount of energy in …

Self-Assembling Of Gold Nanoparticles Array For Electro-Sensing Applications, Islam M. Al-Akraa Dr, Ahmad M. Mohammad Prof, Mohamed S. El-Deab Prof, Bahgat E. El-Anadouli Prof

Chemical Engineering

A colloidal solution of citrate-stabilized gold nanoparticles (AuNPs) with an average size of ca. 2.6 nm has been prepared, characterized and further implemented in electro-sensing applications. This colloidal solution of AuNPs has been prepared via the reduction of NaAuCl4 with sodium tetrahydroborate (NaBH4) using trisodium citrate as a stabilizer. The optical properties of this solution have been studied with UV–Vis spectroscopy. Next, these AuNPs have been immobilized onto a polycrystalline Au (poly-Au) electrode with the assistance of benzenedimethanethiol (BDMT), which served as a binder. Attention has been taken to ensure the formation of a compact impermeable layer of BDMT on …

Food Webs And Food Sovereignty: Research Agenda For Sustainability, Charles A. Francis, Michelle Miller, Molly Anderson, Nancy Creamer, Michelle Wander, Jacob Park, Thomas Green, Brent Mccown

Department of Agronomy and Horticulture: Faculty Publications

Future food production will be constrained by the scarcity of fossil fuel and fresh water as well as increasing intensity and unpredictability of weather events and climate changes. The assurance of food security and equity for many consumers is complicated by concentration of ownership of land and other production resources, as well as a global corporate food systems model that is driven by profit at the expense of people and the environment. To assess potential alternatives to the contemporary global food chain, well focused research is needed on local food production and food webs where small- and midscale family farms …

Global Attracting Equilibria For Coupled Systems With Ceiling Density Dependence, Eric A. Eager, Mary Hebert, Elise Hellwig, Francisco Hernandez, Richard Rebarber, Brigitte Tenhumberg, Bryan Wigianto

School of Biological Sciences: Faculty Publications

In this paper, we present a system of two difference equations modeling the dynamics of a coupled population with two patches. Each patch can house only a limited number of individuals (called a carrying capacity) because resources like food and breeding sites are limited in each patch. We assume that the population in each patch is governed by a linear model until reaching a carrying capacity in each patch, resulting in map which is nonlinear and not sublinear. We analyze the global attractors of this model.

Creating An Interdisciplinary Research Course In Mathematical Ecology, Glenn Ledder, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

An integrated interdisciplinary research course in biology and mathematics is useful for recruiting students to interdisciplinary research careers, but there are difficulties involved in creating and implementing it. We describe the genesis, objectives, design policies, and structure of the Research Skills in Theoretical Ecology course at the University of Nebraska–Lincoln and discuss the difficulties that can arise in designing and implementing interdisciplinary courses.

An Interdisciplinary Research Course In Theoretical Ecology For Young Undergraduates, Glenn Ledder, Brigitte Tenhumberg, G. Travis Adams

School of Biological Sciences: Faculty Publications

As part of an interdepartmental effort to attract promising young students to research at the interface between mathematics and biology, we created a course in which groups of recent high school graduates and first-year college students conducted a research project in insect population dynamics. The students set up experiments, collected data, used the data to develop mathematical models, tested their models against further experiments, and prepared their results for dissemination. The course was self-contained in that the lecture portion developed the mathematical, statistical, and biological background needed for the research. A special writing component helped students learn the principles of …

The Essentials Of Economic Sustainability By John Ikerd [Book Review], Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

Essentials of Economic Sustainability is the latest challenging statement on innovative economic philosophy from an alternative opinion leader John Ikerd, retired agricultural economist from University of Missouri, Columbia (Columbia, Missouri, United States). His perspective is that accelerating changes surrounding us require more than small adaptations, but rather a thoughtful reconsideration of basic principles about how the world works and our role in this dynamic reality. Ikerd paraphrases the challenge of the 1988 Brundtland Report of the United Nations that we must design strategies ‘to meet the economic needs of the present without diminishing economic opportunities for the future’ (page 1). …

Probing The Bifunctional Catalytic Activity Of Ceria Nanorods Towards The Cyanosilylation Reaction, Gonghua Wang, Lu Wang, Xiang Fei, Yunyun Zhou, Renat F. Sabirianov, Wai-Ning Mei, Chin Li Cheung

Department of Chemistry: Faculty Publications

Ceria nanorods were demonstrated to be an active, bifunctional catalyst for the cyanosilylation of aldehydes. The catalytic activity of ceria was shown to be positively correlated with a decrease in the coordination numbers of neighbouring oxygen atoms around cerium atoms in the catalyst. Chemisorption and density functional theory studies suggested that the coordinatively unsaturated cerium sites exposed by the surface oxygen vacancy defects functioned as Lewis acid sites and the neighbouring oxygen atoms behaved as Lewis base sites in the catalytic cycle.

Porous Polymer Coatings As Substrates For The Formation Of High-Fidelity Micropatterns By Quill-Like Pens, Michael Hirtz, Marcus Lyon, Wenqian Feng, Andrea E. Holmes, Harald Fuchs, Pavel A. Levkin

Department of Chemistry: Faculty Publications

We explored the potentials of microarray printing using quill-like microcantilevers onto solid supports that are typically used in microspot printing, including paper, polymeric nitrocellulose and nylon membranes. We compared these membranes with a novel porous poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) support (HEMA) with narrow pore size distribution in the 150 nm range, which demonstrated advantages in pattern definition, spot homogeneity, and consistent spot delivery of different dyes (phloxine B and bromophenol blue) with diameters of several micrometres. The bromophenol blue arrays on HEMA support were used to detect the presence of bovine serum albumin (BSA). In the presence of BSA, …

Single Transcriptional And Translational Preq1 Riboswitches Adopt Similar Pre-Folded Ensembles That Follow Distinct Folding Pathways Into The Same Ligand-Bound Structure, Krishna C. Suddala, Arlie J. Rinaldi, Jun Feng, Anthony M. Mustoe, Catherine D. Eichhorn, Joseph A. Liberman, Joseph E. Wedekind, Hashim M. Al-Hashimi, Charles L. Brooks Iii, Nils G. Walter

Department of Chemistry: Faculty Publications

Riboswitches are structural elements in the 50 untranslated regions of many bacterial messenger RNAs that regulate gene expression in response to changing metabolite concentrations by inhibition of either transcription or translation initiation. The preQ₁ (7-aminomethyl-7-deazaguanine) riboswitch family comprises some of the smallest metabolite sensing RNAs found in nature. Once ligand-bound, the transcriptional Bacillus subtilis and translational Thermoanaerobacter tengcongensis preQ₁ riboswitch aptamers are structurally similar RNA pseudoknots; yet, prior structural studies have characterized their ligand-free conformations as largely unfolded and folded, respectively. In contrast, through single molecule observation, we now show that, at nearphysiological Mg²⁺ concentration and pH, …

Iodonium Cyclophanes For Secure Arene Functionalization, Stephen Dimagno

Department of Chemistry: Faculty Publications

This disclosure relates to compounds, reagents, and methods useful in the synthesis of aryl fluorides, for example, in the preparation of 18F labeled radiotracers. For example, this disclosure provides universal “locked” aryl substituents that result in StereoElectronic Control of Unidirectional Reductive Elimination (SECURE) from diaryliodonium salts. The reagents and methods provided herein may be used to access a broad range of compounds, including aromatic compounds, heteroaromatic compounds, amino acids, nucleotides, and synthetic compounds.

Development Of Affinity Microcolumns For Drug–Protein Binding Studies In Personalized Medicine: Interactions Of Sulfonylurea Drugs With In Vivo Glycated Human Serum Albumin, Jeanethe Anguizola, K. S. Joseph, Omar S. Barnaby, Ryan Matsuda, Guadalupe Alvarado, William Clarke, Ronald Cerny, David S. Hage

David Hage Publications

This report used high-performance affinity microcolumns to examine the changes in binding by sulfonylurea drugs to in vivo glycated HSA that had been isolated from individual patients with diabetes. An immunoextraction approach was developed to isolate HSA and glycated HSA from clinical samples, using only 20 μL of plasma or serum and 6–12 nmol of protein to prepare each affinity microcolumn. It was found that the affinity microcolumns could be used in either frontal analysis or zonal elution studies, which typically required only 4–8 min per run. The microcolumns had good stability and allowed data to be obtained for multiple …

Patron-Driven Acquisition And Circulation At An Academic Library: Interaction Effects And Circulation Performance Of Print Books Acquired Via Librarians’ Orders, Approval Plans, And Patrons’ Interlibrary Loan Requests, David C. Tyler, Christina D. Falci, Joyce C. Melvin, Marylou Epp, Anita M. Kreps

University of Nebraska-Lincoln Libraries: Faculty Publications

Numerous publications on patron-driven acquisition (PDA) for print books and similar materials have reported that patron-requested materials circulate more. Tying circulation to selector may be failing to address the complex of factors that contributes to items’ circulation. In the present study, the authors revisit a PDA program’s data and to determine whether PDA print books’ circulation advantage persists when the potential interactions of several additional variables are taken into account. As with prior studies, library patrons were significantly better predictors of circulation than were librarians or approval plans. However, librarians proved to be significantly better predictors than were approval plans.

Reviews Of Science For Science Librarians: Drought In The Agricultural And Geosciences Literature, Leslie M. Delserone, Adonna Fleming

University of Nebraska-Lincoln Libraries: Faculty Publications

Drought is a hot topic, given the climatic events of summer 2012 in the United States. This article provides a fundamental understanding of drought—its definitions, classifications, ratings, and impact on agriculture. Also included are introductions to drought-related research areas in the geosciences—specifically geology, hydrology, and atmospheric sciences—as well as pointers to reliable sources of information about drought from the agricultural and geosciences literature.

Bacillus Thuringiensis: Transgenic Crops, Julie A. Peterson, John J. Obrycki, James D. Harwood

Department of Entomology: Faculty Publications

Bacillus thuringiensis (Bt) crops, genetically modified to express insecticidal toxins that target key pests of corn, cotton, rice, potato, and other crops, have been rapidly adopted and have become dominant fixtures in agroecosystems throughout the world. Due to the constitutive nature of Bt toxin expression, insecticidal proteins may be found in nearly all plant tissues, presenting multiple sources for Bt toxins to enter the environment, thus creating complex direct and indirect pathways for non-target organisms to be exposed to insecticidal proteins. The environmental impacts of Bt crops have been widely debated, although both benefits and risks do exist. Benefits of …

Saturated Thickness Of The Unconfined Portions Of The High Plains Aquifer, Conservation And Survey Division

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

The Groundwater Atlas Of Nebraska, Jesse T. Korus, Leslie M. Howard, Aaron R. Young, Dana P. Divine, Mark E. Burbach, J. Michael Jess, Douglas R. Hallum, R.F. Diffendal, Jr., R.M. Joeckel

Conservation and Survey Division: Faculty and Staff Publications

Groundwater has long been important to inhabitants of Nebraska. Native Americans in the Great Plains erected their villages near water sources. Early explorers from Europe and pioneers heading west following river valleys depended on ample freshwater in the Nebraska Territory for drinking water and livestock supplies. These Europeans, however, considered the Nebraska Territory part of “The Great American Desert” and few people had an idea of the vast groundwater resource in Nebraska.

Human Performance Regression Testing, Amanda Swearngin, Myra B. Cohen, Bonnie E. John, Rachel K. E. Bellamy

School of Computing: Conference and Workshop Papers

As software systems evolve, new interface features such as keyboard shortcuts and toolbars are introduced. While it is common to regression test the new features for functional correctness, there has been less focus on systematic regression testing for usability, due to the effort and time involved in human studies. Cognitive modeling tools such as CogTool provide some help by computing predictions of user performance, but they still require manual effort to describe the user interface and tasks, limiting regression testing efforts. In recent work, we developed CogTool-Helper to reduce the effort required to generate human performance models of existing systems. …

A Gridded Reconstruction Of Warm Season Precipitation For Asia Spanning The Past Half Millennium, Song Feng, Q. Steven Hu, Qianru Wu, Michael E. Mann

Department of Earth and Atmospheric Sciences: Faculty Publications

The authors reconstructed May–September precipitation over the Asian continent (5°–55°N, 60°–135°E) back to AD 1470 on the basis of tree-ring data, historical documentary records, ice core records, and the few long-term instrumental data series available in the region. They employed the method of Regularized Expectation Maximization (RegEM) and applied it to 44 subregions within the continent. Verification exercises demonstrate that the reconstruction is skillful over most of the study domain, with eastern China, India, and other regions of humid climate displaying the greatest skill. Lower reconstruction skill is observed in semiarid and arid regions, which was attributable at least in …

Optimal Estimation For Global Ground-Level Fine Particulate Matter Concentrations, Aaron Van Donkelaar, Randall V. Martin, Robert J. D. Spurr, Eason Drury, Lorraine A. Remer, Robert C. Levy, Jun Wang

Department of Earth and Atmospheric Sciences: Faculty Publications

We develop an optimal estimation (OE) algorithm based on top-of-atmosphere reflectances observed by the MODIS satellite instrument to retrieve near-surface fine particulatematter (PM_2.5). The GEOS-Chem chemical transport model is used to provide prior information for the Aerosol Optical Depth (AOD) retrieval and to relate total column AOD to PM_2.5. We adjust the shape of the GEOS-Chem relative vertical extinction profiles by comparison with lidar retrievals from the CALIOP satellite instrument. Surface reflectance relationships used in the OE algorithm are indexed by land type. Error quantities needed for this OE algorithm are inferred by comparison with AOD …

Constraints On Aerosol Sources Using Geos-Chem Adjoint And Modis Radiances, And Evaluation With Multisensor (Omi, Misr) Data, Xiaoguang Xu, Jun Wang, Daven Henze, Wenjun Qu, Monika Kopacz

Department of Earth and Atmospheric Sciences: Faculty Publications

We present a new top-down approach that spatially constrains the amount of aerosol emissions using satellite (Moderate Resolution Imaging Spectroradiometer (MODIS)) observed radiances with the adjoint of a chemistry transport model (GEOS-Chem). This paper aims to demonstrate the approach through applying it to a case study that yields the following emission estimates over China for April 2008: 1.73 Tg for SO2, 0.72 Tg for NH3, 1.38 Tg for NOx, 0.10 Tg for black carbon, and 0.18 Tg for organic carbon from anthropogenic sources, which reflects, respectively, a reduction of 33.5%, 34.5%, 18.8%, 9.1%, and 15% in comparison to the prior …

Salinity And Climate Reconstructions From Continental Lakes, Sherilyn C. Fritz

Department of Earth and Atmospheric Sciences: Faculty Publications

Diatoms are widely used to reconstruct past environments because of their sensitivity to a range of environmental variables. Among the variables that exert a strong influence on diatoms are ionic concentration, expressed as salinity or conductivity, and ionic composition. Because the ionic concentration and composition of inland water bodies is affected by changes in effective moisture (precipitation minus evaporation, P – E), changes in the abundance of diatom species that vary in their salinity tolerances provide a tool for the reconstruction of past climate.

Jurassic Earthquake Sequence Recorded By Multiple Generations Of Sand Blows, Zion National Park, Utah, David Loope, James F. Elder, Vitaly A. Zlotnik, Richard M. Kettler, Darryll T. Pederson

Department of Earth and Atmospheric Sciences: Faculty Publications

Earthquakes along convergent plate boundaries commonly occur in sequences that are complete within 1 yr, and may include 8–10 events strong enough to generate sand blows. Dune crossbeds within the Jurassic Navajo Sandstone of Utah (western United States) enclose intact and truncated sand blows, and the intrusive structures that fed them. We mapped the distribution of more than 800 soft-sediment dikes and pipes at two small sites. All water-escape structures intersect a single paleo-surface, and are limited to the upper portion of the underlying set of cross-strata and the lower portion of the overlying set. A small portion of one …