University Library, University of Illinois at Urbana-Champaign

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• Tracking certificate misissuance in the wild
Scholarship
Creator
Wang, Zhengping
Description
Certificate Authorities (CAs) are responsible for delegating trust in the TLS Public Key Infrastructure (PKI). Unfortunately, there is a long history of CAs abusing this responsibility, either due to negligence or in some cases, falling victim to attacks. As a result, the PKI community has established standards that define the correctness of certificates and how a well managed CA should operate. In this work, we evaluate a systematic approach to identifying whether certificates issued by CAs are compliant with community standards. To this end, we present ZLint, a system that determines whether a certificate is not conformant to standards, i.e., misissued. We find that while misissuance has decreased over time, there is still a long tail of non-conformant CAs in the ecosystem. Further, our results show that certificate misissuance serves as a reasonable indicator for mismanagement and untrustworthiness, suggesting that CAs that misissue more frequently pose a greater threat to security of the PKI. Community efforts thus far to curb these threats have been moderately successful, but the lack of a systematic approach to identifying these problems lets some classes of problems slip through the cracks. We argue that an automated and systematic approach to measuring misissuance in the ecosystem is a necessary first step in solving the problems that lie ahead.
• Navigating the PDF/A standard: a case study of theses in the University of Oxford’s institutional repository
Scholarship
Creator
Oates, Anna Irene
Description
The PDF/A (Portable Document Format–Archival) was established by the International Organization of Standardization as the ISO 19005 standard for long-term preservation of electronic documents. While the ISO requirements of a well-formed PDF/A ensure sustainability and easy recovery of content, the standard restricts some document features from being incorporated into a well-formed PDF/A. Non-conformances to the standard are found across electronic theses and dissertations, from non-Latin glyphs used in scientific and language papers to embedded content, such as images. A further complication for achieving ISO 19005 compliance is that, despite non-conformance to the ISO standard, validation tools do not always catch non-conformance errors in documents which claim to conform to PDF/A. While PDF/A is a logical solution for long-term preservation of electronic documents, the stringent standard prevents some content which is frequently used in academic research from conforming to the ISO 19005 standard. This thesis evaluates the PDF/A and its potential use as a preservation file format for electronic theses and dissertations.
• Feeding peroxidized soybean oil to finishing pigs: Effects on performance, nutrient digestibility, carcass...
Scholarship
Creator
Overholt, Martin F.
Description
• Food safety through fungal disease and mycotoxin mitigation on dairy farms: From field to feed and the rumen
Scholarship
Creator
Weatherly, Maegan Elizabeth
Description
• Essays in debt sustainability and financial stability
Scholarship
Creator
Henao Arbelaez, Camila
Description
In chapter one, I construct a dynamic stochastic general equilibrium model of optimal default, in which the government optimally holds net debt and attachable assets. The model is novel as it allows for the possibility of debt to be enforced. This is a vast improvement upon previous models, which find that the optimal level of assets the sovereign chooses in the long run is zero. Here, asset savings have other roles different than consumption smoothing. They impact repayment incentives and borrowing costs. Whenever debt is enforceable through a fraction of assets that can be confiscated should the government default, equilibrium attachable asset holdings can be different than zero. I find that attachable asset holdings and attachability, increase debt sustainability, and further provide access to funds. The main mechanism by which this occurs is the endogenous interest rate. It is found to be decreasing in the attachability parameter, and increasing in the probability of redemption. I calibrate $\alpha$ to match observed attachable asset levels. Results indicate a ninefold increase in attachability from the late 1990s to 2010 (from $10\%$ to $93\%$); these results then allow me to match the observed rising trend in attachable asset holdings since the late 1990s. In synthesis, this paper argues that larger attachability—which can be interpreted as relentless litigation, severe threats of confiscation, and less favorable rulings toward sovereigns—explains the rise in the observed percentage of debt attached and attachable asset holdings. In chapter two, we ask if government financial assets help improve public debt sustainability. We assemble a comprehensive dataset on government assets using multiple sources and covering 110 advanced and emerging market economies since the 1980s. We then use this rich database to estimate the impact of assets on two key dimensions of debt sustainability: borrowing costs and the probability of debt distress. Government assets significantly reduce sovereign spreads and the probability of debt crises in emerging economies, but not in advanced economies; this effect varies with asset characteristics, notably liquidity. Assets also help discriminate among countries across the distribution of sovereign spreads, thus signaling information about emerging economies’ creditworthiness. Chapter three systematically documents the impact on output dynamics of an additional unit of debt-to-tax revenue, conditional on the occurrence of financial shocks. I examine whether banking crises are systematically different from other financial catastrophes (currency crises), and, most importantly, whether pre-crises fiscal buffers are particularly important whenever banking crises materialize. Lastly, the paper investigates post-crisis output dynamics considering pre-crisis debt-to-tax revenue, and examine whether the post-crisis dynamics are systematically different for emerging and developing economics than for advanced economies. Using panel data for 155 countries for the period of 1975-2011, I estimate a univariate autoregressive model in growth rates, and construct impulse response functions to display the relationship between debt-to-tax-revenue conditional on a financial crisis and output dynamics. Using three approaches to account for the endogeneity of crises and fiscal burden, I find that an additional unit of debt-to-tax revenue prior to a banking crisis is associated with larger output losses than when the same situation occurs prior to a currency crisis. Emerging and developing economies experience deeper losses than advanced countries; this is due not only to banking and currency crises, but because of marginal increases in the pre-crisis debt-to-tax-revenue ratios.
• Closing yield gaps in South Asian wheat production (Bihar, India and Terai of Nepal)
Scholarship
Creator
Park, Alexander Guy
Description
• Exploring photo elicitation to engage head start families of children with disabilities
Scholarship
Creator
Hile, Kimberly Ann
Description
The Individuals with Disabilities Education Act mandates that children with disabilities be provided with individualized supports to maximize their overall development and learning. Caregivers of children ages birth to 5 years play an integral role in determining what supports are most beneficial for the child and their family. Research related to family empowerment and capacity-building suggest that families facing multiple risk factors (e.g., presence of a disability, poverty, single parents, and low levels of maternal education) may experience feelings of powerlessness when asked by professionals to make decisions on behalf of their families. The purpose of this study was to identify effective ways to engage families experiencing multiple risk factors including caring for young children with disabilities, to work collaboratively with Head Start professionals when planning and implementing family-centered interventions. Specifically, collaborations between families and Head Start Family Service Workers and the potential utility for a particular strategy, “photo elicitation,” to empower families to share their personal stories as a pathway to building meaningful relationships was examined. A qualitative approach via thematic analysis was utilized. Findings from this study begin to address the need for identifying innovative strategies for building family capacity with Head Start families, specifically those caring for young children with disabilities.
• The effects of zinc source and supplemental copper on growth performance, carcass characteristics, and morbidity and...
Scholarship
Creator
Schmitt, Rachel Loren
Description
• Interfacial spallation/delamination properties of self-assembled monolayers
Scholarship
Creator
Zhang, Chen
Description
Self-assembled monolayers (SAMs) are short (nanometer-size) organic chains terminated by functional groups that can be selected to tailor the electrical, thermal and/or mechanical properties of interfaces. In this thesis, we investigate how the presence of SAMs affects the failure properties of gold film/silicon/fused silica substrate interfaces. In particular, we study how the presence of SAMs affects (i) the spallation strength and (ii) the fracture toughness of the interface. The modeling work summarized in this thesis is motivated by previous results of molecular dynamic (MD) simulations and laser-induced spallation/delamination tests to quantify the strength and toughness of SAM-enhanced interfaces. Though the results obtained from MD simulations and experimental observations yielded similar trends in comparing the contribution of various SAMs, their actual values were off by significant amounts. The research presented in this dissertation involves the development of continuum-level numerical models to analyze the dynamic spallation and delamination events to fill the gap between MD simulations and experimental results. In the first part of the thesis, a continuum-level study is performed to investigate the influence of surface roughness on the cohesive strength of the interface between a fused silica/SAM substrate and a transfer-printed gold film. We approximate the film as a deformable continuum interacting with a rough substrate of SAM. Using the cohesive law predicted by MD, spallation is simulated to evaluate the effective traction-separation characteristics for the rough SAM-gold interface. The separation attributes based on roughness parameters and material properties of gold film are observed. The dependence of the interfacial cohesive strength of SAM-enhanced interface on incorporating roughness and the thin film properties is studied. In the laser-induced delamination test, the interface fracture energy is computed by assuming all of the kinetic energy imparted into the weak adhesion layer of the film is converted into fracture energy. However, part of this effective interface fracture toughness is associated with plastic deformations in the film. To quantify the plasticity contribution to the effective fracture toughness of the SAM-enhanced interface, we perform an implicit finite element numerical analysis of the dynamic delamination event that incorporated both large deformation and plasticity effects. Cohesive elements whose failure law is derived from MD simulations are introduced along the interface to simulate the failure initiation and debonding process. The amount of dissipated plastic energy is quantified and the film profile is depicted depending on the properties of the thin film and the interfacial attributes. The model is validated with experimental measurements of the crack propagation length, profile of the debonded thin film, and interfacial fracture energy.
• Creating a PCI express interconnect in the gem5 simulator
Scholarship
Creator
Srinivasan, Krishna Parasuram
Description
In this thesis, the objective was to implement a PCI (Peripheral Component Interconnect) Express interconnect in the gem5 architecture simulator. The interconnect was designed with the goal of aiding accurate modeling of PCI Express-based devices in gem5 in the future. The PCI Express interconnect that was created consisted of a root complex, PCI Express switch, as well as individual PCI Express links. Each of these created components can work independently, and can be easily integrated into the existing gem5 platforms for the ARM Instruction Set Architecture. The created PCI Express interconnect was evaluated against a real PCI Express interconnect present on an Intel Xeon server platform. The bandwidth offered by both interconnects was compared by reading data from storage devices using the Linux utility “dd”. The results indicate that the gem5 PCI Express interconnect can provide between 81% - 91.6% of the bandwidth of the real PCI Express interconnect. However, architectural differences between the gem5 and Intel Xeon platforms used, as well as unimplemented features of the PCI Express protocol in the gem5 PCI Express interconnect, necessitate more strenuous validation of the created PCI Express interconnect before reaching a definitive conclusion on its performance.
• Nelson Oppen combination as a rewrite theory
Scholarship
Creator
Rodrigues, Nishant
Description
Solving Satisfiability Modulo Theories (SMT) problems in a key piece in automating tedious mathematical proofs. It involves deciding satisfiability of formulas of a decidable theory, which can often be reduced to solving systems of equalities and disequalities, in a variety of theories such as linear and non-linear real and integer arithmetic, arrays, uninterpreted and Boolean algebra. While solvers exist for many such theories or their subsets, it is common for interesting SMT problems to span multiple theories. SMT solvers typically use refinements of the Nelson-Oppen combination method, an algorithm for producing a solver for the quantifier free fragment of the combination of a number of such theories via cooperation between solvers of those theories, for this case. Here, we present the Nelson-Oppen algorithm adapted for an order-sorted setting as a rewriting logic theory. We implement this algorithm in the Maude System and instantiate it with the theories of real and integer matrices to demonstrate its use in automated theorem proving, and with hereditarily finite sets with reals to show its use with non-convex theories. This is done using both SMT solvers written in Maude itself via reflection (Variant-based satisfiability) and using external solvers (CVC4 and Yices). This work can be considered a first step towards building a rich ecosystem of cooperating SMT solvers in Maude, that modeling and automated theorem proving tools typically written using the Maude System can leverage.
• Development of an ultraprecision shaping machine for manufacturing of Stavax lens molds
Scholarship
Creator
Moore, Jack
Description
The production of high-precision aspheric microlenses has become increasingly difficult due to an increase in the complexity of the profile, the decrease in the lens’ size, and the demand for tighter tolerances. Machines built to fabricate these lenses generally include several expensive components due to the stringent stiffness, resolution, and bandwidth requirements necessary for proper machining. This thesis deals with reducing the cost of production by building an ultraprecision shaping machine that is comprised of three reasonably priced custom made axes that meet the requirements needed for ultraprecision machining. These three axes are (1) a flexure-based, single DOF axis driven by a voice coil actuator, (2) an inchworm axis driven by an assembly of five piezoelectric actuators, and (3) a long range fast tool servo driven by a large piezoelectric actuator. These three axes were developed individually to meet a set of requirements determined necessary for the machining of a microlens mold array in Stavax, a stainless steel variant. Each axis was designed such that it would not fail due to fatigue failure, was capable of achieving a high resolution (< 10 nm), and had a high stiffness in the degrees of constraint (> 200 N/µm). The X-axis needed a range greater than 250 µm, the Y-axis needed a range greater than 3 mm, and the Z-axis needed a range greater than 35 µm. The X-axis needed to be capable of following a low frequency sine wave, while the Z-axis needed to be capable of following high frequency wave forms (200 Hz). Simulations were performed to determine if the designs would meet all the requirements set. All the designed axes have met the requirements, but only the X- and Y-axes have been manufactured for testing. Preliminary testing has shown that the X-axis has at least a stiffness of 60 N/µm in both the degrees of constraint. Movement in the parasitic directions while the axis was being actuated was also tested and showed that the only movement in the parasitic directions is when the X-axis crosses the zero point. Most likely, this is due to the electronics being used, which are also making it difficult to determine the full range of the axis and close the loop. Testing on the Y-axis has revealed that it has a stiffness of at least 125 N/µm in the direction of motion and stiffnesses between 60 N/µm and 100 N/µm in the degrees of constraint. The axis is capable of running at a speed of 150 µm/s, which is only limited by the amplifiers being used. Closed loop testing has shown that the axis is capable of 10 nm steps.
• Second-harmonic generation-based Mueller matrix polarization analysis of collagen-rich tissues
Scholarship
Creator
Okoro, Chukwuemeka
Description
Quantitative assessment of the properties of fibrillar collagen in tissue can yield deeper insight into structure-function correlations of the cell and its surrounding matrix. Second-harmonic generation (SHG) microscopy is especially well-suited as an image acquisition technique, due to its specificity to the non-centrosymmetric structure of collagen, and inherent confocality which enables three-dimensional sectioning. SHG imaging can be undertaken in a quantifiable manner, or combined with other techniques that highlight desired properties. A powerful property for characterizing collagenous tissue microstructure is the Mueller matrix polarization response. Two polarimetric imaging approaches are demonstrated for robust Mueller matrix characterization of collagenous tissue. One approach, called the two-photon Mueller matrix second-harmonic generation (MMSHG) microscopy, involves the generalization of Mueller matrix to the case of two-photon excitation. This 4-by-9 two-photon Mueller matrix is extracted using second-harmonic generation microscopy and analyzed for quantitative collagen assessment. The matrix and associated degree-of-polarization parameter from different sample types and thicknesses are also investigated. It was observed that the polarization-dependent degree-of-polarization distribution shape changes and a model-based bimodal mean difference metric increases with sample thickness. The second polarization technique which we developed, called second-harmonic patterned polarization-analyzed reflection confocal (SPPARC) microscopy, uses the conventional linear polarimetry of confocal images, delineated with a second-harmonic mask. This latter approach, combining the metric richness of linear polarimetry with the specificity of SHG imaging, is used for assessing collagen, as well as non-collagenous regions, in porcine tendon and ligament. We observed differences in depolarization and circular degree-of-polarization parameters, that have potential for dfferentiating tissues in varying states. Next, we present the results of SPPARC microscopy and analysis of collagen on varying pathologies of breast tissues. Experiments were conducted on a breast tissue microarray having benign tissues (BT), malignant invasive lobular carcinoma (ILC), and benign stroma adjacent to the malignant tissues (called the benign adjacent tissue, or BAT). We observed that stroma in BAT and ILC exhibits the largest parameter differences, with collagen readings in ILC showing lower depolarization, lower diattenuation and higher linear degree-of-polarization values than stromal collagen in BAT. This result suggests that the optical properties of collagen change most in the vicinity of tumors. A similar trend is also exhibited in the non-collagenous extrafibrillar matrix plus cells (EFMC) region. We finally discuss additional work involving polarization modeling, setup optimization, and implementation of other decomposition techniques.
• Stacks in Poisson geometry
Scholarship
Creator
Villatoro, Joel David
Description
This thesis is divided into four chapters. The first chapter discusses the relationship between stacks on a site and groupoids internal to the site. It includes a rigorous proof of the folklore result that there is an equivalence between the bicategory of internal groupoids and the bicategory of geometric stacks. The second chapter discusses standard concepts in the theory of geometric stacks, including Morita equivalence, stack symmetries, and some Morita invariants. The third chapter introduces a new site of Dirac structures and provides a rigorous answer to the question: What is the stack associated to a symplectic groupoid? The last chapter discusses a remarkable class of Poisson manifolds, called b-symplectic manifolds, giving a classification of them up to Morita equivalence and computing their Picard group.
• Relyzer+: An open source tool for application-level soft error resiliency analysis
Scholarship
Creator
Ahmed, Khalique
Description
In the modern era of computing, processors are increasingly susceptible to soft errors. Current solutions in both hardware and software enable error detection and correction. Some of these errors, however, go unnoticed by detectors and manifest as silent data corruptions (SDCs) at the application level. Injecting errors into the system and evaluating the outcomes is one method to uncover SDC-causing errors and determine an application's overall resilience to soft errors. The number of possible locations that errors may appear in is large, therefore requiring many injection experiments. One resiliency analysis tool, Relyzer, addresses this issue by performing a comprehensive program analysis to create a small subset of the error injection experiments that can account for the entire application. The limitation of Relyzer is that current analysis can only be performed on one hardwarware instruction set architecture (ISA). Software is usually compiled to multiple ISAs in order to support users with varying hardware configurations. The primary contribution of this thesis is building Relyzer, an open source version of Relyzer implemented using the gem5 simulator. This enables the capability to analyze multiple ISAs and consequently support multiple hardware configurations in the long-term. Specifically, in this work, we develop support for x86. We also evaluate applications across ISAs by generating error resiliency profiles for both x86 and SPARC. After studying five workloads from different domains, we find that in general, application soft error resiliency varies based on the selection of the ISA. The percentage of static instructions that yield SDCs is, on average, 68\% for x86 and 60\% for SPARC, for the applications we studied. Furthermore, this work opens doors to future research in application-level soft error resiliency analysis.
• Fatigue crack growth in hydrogen pipeline steels
Scholarship
Creator
Che, Ziwei
Description
Pipeline hydrogen transport and distribution are contemplated for hydrogen applications. Hydrogen introduction in the natural gas pipeline systems is also considered in the power to gas (P2G) approach to utilizing excess renewable energy when the supply exceeds the demand. It is well known that hydrogen embrittles all carbon steels used to manufacture pipelines and hence, safety and reliability of hydrogen transport requires that pipelines be assessed and tested against hydrogen embrittlement. The most severe embrittlement mechanism is hydrogen accelerated fatigue crack growth since it is well known that hydrogen can enhance fatigue crack growth rates by a factor of 10. In this thesis, the fatigue life of a line pipe manufactured with API steel is calculated by investigating the growth of a semi-elliptical crack on the inner diameter surface due to hydrogen pressure fluctuation. This behavior is compared with the life of the line pipe in an inert environment (e.g. natural gas or N2) under the same pressure fluctuations. The hydrogen or the inert environment pressure history is analyzed with the rainflow counting method and the crack depth calculations are carried out for a variety of API steels at load ratios for a given initial crack depth. The load ratio R equals where and are respectively the minimum and maximum stress intensity factors in a pressure cycle the crack experiences due to the pressure fluctuations. In particular for API X42 steel for which experimental data are available for calculations with greater load ratio, the fatigue life is calculated at load ratios and . The calculation of the stress intensity factor was done by using the closed form solution of Zahoor for which the validity range with regard to the crack and line pipe dimensions was established through comparisons with numerical calculations. The results demonstrate that hydrogen markedly accelerates crack growth and the initial crack depth has significant effect on the pipeline life.
• Power-law liquid in high-temperature superconductors
Scholarship
Creator
Leong, Zhidong
Description
Inspired by recent photoemission measurements, we demonstrate that the normal state of cuprate superconductors can be described by a power-law liquid, a state of matter with a power-law self-energy $\Sigma^{\pr\pr}\sim(\omega^{2}+\pi^{2}T^{2})^{\alpha}$. The scaling exponent decreases from $\alpha\sim1$ in the overdoped Fermi-liquid state to $\alpha\lesssim\frac{1}{2}$ in the optimal and underdoped regime. We find that broad scale invariance of a power-law liquid leads to the cuprates' superconducting dome, vanishing Fermi velocity, and diverging effective mass. We propose that a power-law liquid can arise from the presence of a scale-invariant sector known as unparticles. To extend the power-law liquid framework to include the ubiquitous magnetic phases of high-$T_{c}$ superconductors, we study the local-itinerant dichotomy in iron pnictides. We show that an interplay between localized moments and itinerant electrons is needed to reproduce the spin excitations observed in inelastic neutron scattering experiments. These results further our understanding of the degrees of freedom in high-$T_{c}$ superconductors and will help formulate a consistent framework incorporating the physics of the antiferromagnetic, normal, and superconducting states.
• A language independent debugger semantics based debugging in K
Scholarship
Creator
Saxena, Manasvi
Description
This works presents the K debugger - a language independent program debugger. The debugger is a part of the suite of tools that form the K framework. Conventional language dependent debuggers rely on an ad-hoc model of the underlying programming semantics, and may thus be incapable, or inaccurate in their ability to rectify a program’s behavior. The K debugger uses a different approach - it’s parametric over the K semantics of the programming language, which exposes accurate and subtle faults. The K debugger generalizes behaviors of conventional debuggers, providing users with a uniform interface that works across programming languages. Moreover, the K debugger is formal, performant and highly configurable, allowing it to adapt to the any programming language. This makes the K debugger a suitable replacement to traditional language specific debuggers.
• Lion: Listen online. Using GraphQL as a mediator for data integration and ingestion
Scholarship
Creator
Tubbs, Dustyn James
Description
Data integration is the task of providing a unified view of multiple data sources. Thesesources can be, and are typically, heterogeneous in their data model, data query language (DQL), and data manipulation language (DML). In this thesis is described a system called”Listen Online”, or Lion for short. Lion utilizes the GraphQL specification to provide integration for querying of web services. Lion provides a general structure by which arbitrary mediators can be used within a query. Lastly, by building on top of open source libraries,Lion provides the open source community with components that enable it to function in the form of GraphQL servers, visual layout libraries, and query builders.
• Water Demand in the Kankakee Water Supply Planning Subregion, 2010-2060
Scholarship
Creator
• Zhang, Zhenxing
• Kelly, Walton R.
• Abrams, Daniel
• Dziegielewski, Benedykt
• Meyer, Scott C.
• Geospatial analysis of residential mobility in media: Selling buildings and buying homes
Scholarship
Creator
Shakespeare, Rebecca
Description
Americans love media about house-hunting; by analyzing media representations of house-hunting, we can understand more about the reasons that people move and how media narratives reinforce particular ideas about housing. This data visualization contributes to literature highlighting how house-hunting media content, like HGTV, reinforces the idea of housing as a commodity. Using New Yorkers’ residential histories, derived from the text of Joyce Cohen’s weekly real estate column “The Hunt” from the New York Times in 2017, this shows two households’ similar experiences of housing as a commodity. Vertical lines represent the time that households spent living in a specific area and horizontal connectors indicate times that they moved. In the inset, specific events which impacted residential mobility are displayed at the times and locations the events occurred. Two of the fifty weekly columns analyzed included “building sold” as a reason for moving. These households’ demonstrate two ways that housing is treated as a commodity: first, as renters’ buildings are sold for profit; second, as renters buy housing as investments. This geographic visualization of stories, called geo-narrative, provides a spatially and temporally situated view of the intertwined experiences of residents in the same city. Source: The Hunt, weekly house-hunting column in the New York Times.
• Marital status across the world
Scholarship
Creator
Worthington, Andrea
Description
The poster has a multidimensional diagram that represents material status across the world using radar graphs. Each graph has 5 points to represent age ranges from 15 to 65 +. The different sizes of pentagons represent population percentages. Furthermore, the different colored graphs represent male or female and if they are single or married. In addition, the single data also includes divorced and widowed people. This was done to simplify the data. As a result, the data shows the differences between countries and their marital status. The viewer sees how more people are married in Asia then in the United States. Additionally, female teenagers in India have a higher percentage of being married then teenagers in the United the States. In conclusion, the data shows how culture and location effects differences in marital status and creates curiosity into what factors effect why it is different.
• 9 important facts about GIES courses in summer 2018
Scholarship
Creator
Cao, Yingying
Description
This infographic was made per the preliminary survey of online courses in summer 2018. It gives an overview of students’ basic information and their concerns about the courses. Instructors will know better about their students through this info-graphic and can make some adjustments to make the courses fit students better. It also gives a reference for our eLearning office. So we know what technical support to provide to make the learning environment more friendly for students. Thank you for my instructor, Norma who gave me many suggestions for this infographic. Thank you for the eLearning team that trust me and give me the data to do this research.
• Chicago area background contaminants in wetland sediments and surface waters: Supporting the Calumet Wetlands...
Scholarship
Creator
• Chow, Teresa
• Bordson, Gary
• Bogner, William
• Wiedenmann, Luann
• Talbott, Jonathan
• Wilcoxon, Monte
• Piwani, Marvin
Description
The Illinois Department of Natural Resources funded a study at the lllinois Waste Management and Research Center and the Jllinois State Water Survey, to investigate background concentrations of toxic environmental contaminants in the south Chicago area. The study, funded through the Environmental Protection Trust Fund, was undertaken to provide background information on environmental contaminants in support of the Chicago Department of Environment's efforts to revitalize wetlands in the Calumet region of South Chicago. An important component of the revitalization effort is defining ecotoxicological risks in these environments. Criteria to minimize such risks have been developed by the Calumet Ecotox Protocol Technical Team (2005). Surface water and sediment background concentrations for the region's wetlands were identified as lacking. Eight ponds and lakes were sampled for surface waters and sediments. These samples were analyzed for a variety of toxic metal and organic constituents as well as a number of major constituents and other system properties. The water column was largely free of toxic constituents - median values for the measured parameters are provided for the surface waters. The sediment data was subjected to rigorous statistical assessment to generate defensible background concentrations for the region.
• INHS Reports, December 1987
Scholarship
Creator
Illinois Natural History Survey
Description
Phyllophaga | Winter Populations of Bald Eagles in Illinois | Land Use/Cover and Stream Water Quality
• INHS Reports, April 1988
Scholarship
Creator
Illinois Natural History Survey
Description
Mussel Die-offs of Biological or Chemical Origin? | Alkaline Hydrogen Peroxide-Treated Straws as Feeds for Crayfish | Plant Cell Response to Stress
• INHS Reports, January 1986
Scholarship
Creator
Illinois Natural History Survey
Description
Mushrooms and Spring Fever | Pine Squirrels in Deciduous Forests | Conservation Tillage and Pesticides
• INHS Reports, October 1986
Scholarship
Creator
Illinois Natural History Survey
Description
Seasonal Dynamics in Small Wetland Ponds | In Memoriam Philip Wayne Smith | Lead Poisoning in Waterfowl
• Water Supply Planning: Middle Illinois Assessment of Water Resources for Water Supply-Final Report
Scholarship
Creator
• Kelly, Walton R.
• Zhang, Zhenxing
• Mannix, Devin H.
• Thomason, Jason F.
• Knapp, H. Vernon
• Dziegielewski, Benedykt
• Lian, Yanqing
• Abrams, Daniel B.
• Meyer, Scott C.
• INHS Reports, June 1987
Scholarship
Creator
Illinois Natural History Survey
Description
Natural Resources Book Ready for Distribution | Mycology of Cypress Swamps | Biologic and Genetic Diversity of Illinois Plants
• Illinois Fire Service Institute - 2009 Winter Fire School Flier
Scholarship
Creator
Illinois Fire Service Institute
Description
This marketing flier, produced in 2009, describes the information and courses offered during the Winter Fire School at the Illinois Fire Service Institute.
• Osaka City University-University of Illinois Urbana-Champaign Symposium 2018 Itinerary
Scholarship
Creator
• Chang, Yuchia
• Liao, Tim F.
• Osaka City University-University of Illinois Symposium 2015 Itinerary
Scholarship
Creator
• Wang, Yimin
• Oyler, Elizabeth
• Response of chromium and chromium-aluminum coatings on zircaloy-2 to high temperature steam
Scholarship
Creator
Zhong, Weicheng
Description
High temperature steam exposure leads to rapid oxidation of Zr based cladding, which will potentially lead to cladding failure. Our approach is to apply CrAl or Cr coatings on Zircaloy by magnetron sputtering to improve the oxidation resistance of cladding materials. The goal of this research is to characterize the oxidation kinetics and microstructure of CrAl and Cr coatings on Zircaloy-2 in high temperature steam (HTS) environment, and to provide information regarding its functionality during off-normal transient in light water reactors. Pure Cr coating and CrAl coatings with various compositions were exposed to 700C steam environment for up to 20 hours. Weight gain of coated Zircaloy was significantly reduced by two to three orders of magnitude by the CrAl and Cr coatings. Oxidation of Zircaloy substrate was inhibited by the 1um coatings for over 20 hour. Composition of coatings has a significant effect on the oxide formation. CrAl coatings with over 43 at % Al concentration developed a continuous layer of γ-Al2O3, and demonstrated lower weight gain. CrAl coatings with below 33 at % Al concentration formed a outer Cr2O3 scale with inner Al2O3 morphology. Pure Cr coating developed a layer of Cr2O3, and had a higher weight gain than CrAl coatings. Oxidation kinetics was quantified on two of the coatings, 42/58 CrAl and 81/19 CrAl, which represented different oxide structure. The Al2O3 growth on 57/43 CrAl was fitted to two different oxidation kinetics with similar confidence. The Al2O3 growth kinetics up to 20 hours can be described by either power-law oxidation kinetics thickness = 25 x time0.27 or direct logarithmic kinetics thickness = 26 x log(time) + 21.4 with the thickness in the unit of nanometer and time in the unit of hour. The Cr2O3 growth on 81/19 CrAl was quantified by the parabolic kinetics as thickness = 77.6 x time0.49. Coating constituent elements diffused to the substrate and formed intermetallic phases with the Zircaloy substrate. The amount of coating constituents for the diffusion to Zircaloy substrate was compared to that for the oxide formation. For Al rich coatings (42/58 CrAl and 57/43 CrAl coatings), greater amount of Al diffused to Zircaloy substrate than to the oxide formation. However, for Cr rich coatings (67/33 CrAl, 81/19 CrAl and Cr coatings), greater amount of Cr diffused to oxide formation than to Zircaloy substrate. The diffusion of coating constituents to Zircaloy substrate formed intermetallic phases, and the composition and the thickness of the intermetallic phase layers depended on the coating composition. Thicker layers of intermetallic phases developed on the coatings with higher Al composition. The intermetallic phases included Fe and Ni, indicating the dissolution of second phase particles (SPPs) during HTS exposure. The stability of intermetallic SPPs in coated Zircaloy-2 was studied in 700C steam environment. Hydrogen generated from the steam oxidation of uncoated Zr were absorbed and formed δ-hydrides in Zircaloy matrix. Synchrotron XRD demonstrated that longer exposure times increased hydride peak intensity and decreased intermetallic SPPs peak intensity. A concentration of 1000 wppm hydrogen in Zircaloy was estimated using synchrotron XRD after 20 hours exposure in 700C steam environment. Cross-section SEM analysis verified the intermetallic SPPs volume fraction reduction. The volume fraction of intermetallic SPPs was 1.7% in as-received Zircaloy, and it dropped to 1.4% after 5 hours exposure, and to 0.4% after 20 hours exposure. The size distribution of intermetallic SPPs was characterized and larger particles appeared to dissolve at longer exposure. A correlation between the hydrogen concentration and the volume fraction of intermetallic SPPs at 700C steam environment was found, with the volume fraction of SPPs decreasing as hydrogen concentration increases, which could be attributed to the strain from the hydrogen uptake into Zircaloy. Oxidation behavior of CrAl or Cr coated Zircaloy was also examined after 1100C steam exposure for two hours. Coatings with higher Cr composition lead to lower weight gain of Zircaloy. We believed that the inward diffusion of Al perturbed the ZrO2 formation, and exacerbate the oxidation behavior. This lead to thicker ZrO2 formation.
• Analysis of sediment dynamics in intensively managed landscapes
Scholarship
Creator
Yu, Mingjing
Description
The flux of fine sediment within agricultural watersheds is an important factor determining the environmental quality of streams and rivers. Human activity has significantly altered the hydrological and biogeochemical cycles within terrestrial and aquatic environments through agricultural intensification, tile drainage installation, and urban development. The study of watershed-scale sediment dynamics is of great value for understanding and predicting the response of sediment dynamics to intensive human impact and is crucial to developing management strategies for reducing the vulnerability of the ecosystem to future changes. The primary objective of this dissertation is to investigate sediment sources, sediment transport, and sediment yield in an intensively managed agricultural landscape. This objective was accomplished by combining of field sampling and measurements, laboratory analysis, sediment fingerprinting study, statistical analysis and modeling exploration in the Upper Sangamon River Basin, Illinois. The relative contributions from cropland, grassland, forested floodplain, upper grazed floodplain, and lower grazed floodplain to the suspended sediment in the stream are evaluated by sediment fingerprinting techniques. The grazed areas of the floodplain are identified as the primary source of fine suspended sediment within the headwaters of the Sangamon River. Erosion of the floodplain both by surface runoff and by streambank erosion contribute to the production of almost all fine sediment sampled within the stream system. The results are consistent both for event and aggregated samples and for large and small events. The fingerprinting results are also consistent with visible and historical evidence of active erosion of grazed areas of floodplain upstream from the in-stream sampling location. Evidence from field reconnaissance and inspection of aerial photography supports the conclusion that cattle grazing plays an important role in accelerating floodplain and streambank erosion. The relationships between rainfall, discharge, and suspended sediment concentration are examined by sediment rating curve approach and hysteresis analysis. Sediment rating curves developed for three sites along the Sangamon River all have a peaked pattern with a transition point at geometric mean of discharge, indicating suspended sediment load in the stream is far below the stream transport capacity during high flows. Spatially, suspended sediment concentrations tend to become more coincident with the seasonality of rainfall and discharge with increasing watershed size and the mean suspended sediment concentration decreases as drainage area increases. Temporally, the SRCs developed for the rising and falling limbs of hydrographs and the four sampling seasons also exhibit the same trends, suggesting that these trends are not scale-dependent. The peaked pattern of sediment rating curve is most apparent in sediment rating curve developed on discharge and sediment data collected in summer, which means the limitation of sediment supply is most significant in summer. Sediment fluxes in modern times and before European settlement is investigated by using a semi-distributed, coupled hydrologic and sediment model. Intensive agricultural activities since European settlement have increased sediment supply and enhanced suspended sediment load in stream, and also influence re-distribution of detached sediment within the system. The percent of sediment supply from each source to the total amount of mobilized sediment significantly changed from 1840s to 2000s, and the agricultural uplands have become the major source of suspended sediment in the stream. The model estimates that sediment supply from uplands increased 11-fold from the 1840s to 2000s, and sediment yield in 2000s is 9 times of that in 1840s. A higher percent of sediment is transported out of the system and deposited in the channel in 2000s than in 1840s. Suspended sediment load has increased more rapidly than floodplain sedimentation. The re-distribution of detached sediment is also influenced by the presence of built levees and extended channel network. With the increased sediment supply and decreased percent of floodplain sedimentation, sediment delivery ratio for the entire watershed only increased 4%. In conclusion, the integrated results from field, statistical and modeling studies advance the knowledge and understanding of sediment supply, delivery, and export in intensively managed landscapes. The findings also inform management strategies aimed at reducing the vulnerability of this landscape to ongoing human impact.
• Utilization of fine recycled concrete aggregate and alternative testing for controlled low-strength materials
Scholarship
Creator
Henschen, Jacob Daniel
Description
With ever-increasing emphasis on sustainability, recycling concrete as aggregate has continued to be an important topic. While the use of the coarse fraction of recycled concrete has become commonplace, the fine fraction is largely regarded as a waste material with few outlets for its use. In this thesis, the use of recycled fine concrete aggregate is investigated for use as a source of internal curing in new concrete and as the aggregate in controlled low-strength materials. Characterization of the recycled fine concrete aggregate did not indicate the presence of appreciable quantities of reactive materials, but the recycled aggregates do possess high absorption capacities, which indicates a potential for internal curing. The ability to provide internal curing is tested using autogenous shrinkage measurements. The mixture design method previously develop for controlled low-strength materials is further validated using alternative material combinations. In addition, dynamic cone penetrometer testing and accelerated curing methods are applied to the controlled low-strength material in order to better characterize the strength of the material. The internal curing tests indicated a potential for recycled aggregates to be used for internal curing. The results from the mixture design validation support the previous conclusions that slump flow is highly reliant on the paste volume. The subsidence and strength are both tied to the cement content and the water to cementitious ratio. The findings of the dynamic cone penetrometer tests suggest that it is a viable in situ test for controlled low-strength material. The in situ testing are then correlated with the unconfined compressive strength. Using elevated temperatures to cure controlled low-strength materials did result in significant strength increases over room temperature curing. The higher early strengths from the accelerated curing provides valuable information on the maximum strength that can be achieved from a mixture. The strength gain as a function of time and temperature is modeled for controlled low-strength materials using virgin fine aggregates.
• Observed microphysical characteristics and inferred thermodynamic processes contributing to the structure, evolution,...
Scholarship
Creator
Stechman, Daniel M.
Description
During the 2015 Plains Elevated Convection at Night (PECAN) project, airborne radar and optical array probe data were collected within 42 spiral ascents/descents of the NOAA P-3 aircraft across various regions of six mesoscale convective systems (MCSs) at multiple stages of system development. These spirals sampled MCSs corresponding to various archetypes, including several conforming to the classic leading-line/trailing-stratiform mode, and others conforming to the parallel stratiform, leading stratiform, and nonlinear system modes. In one case observations were made in the stratiform region trailing a frontal squall line. Multiple-Doppler syntheses of the wind and reflectivity fields within the 20 June 2015 MCS were used to understand the microphysical and thermodynamic characteristics observed in the spirals in the context of the MCS reflectivity and kinematic structure. A second component of this study was a statistical analysis of the microphysical and thermodynamic structures observed in 37 PECAN spirals. The thermodynamic and microphysical structure of the MCSs were analyzed in the context of three primary MCS regions, namely the transition zone (TZ), enhanced stratiform rain region (ESR), and the anvil region (AR). The 20 June MCS analysis showed that within the transition zone coincident with the rear inflow notch, cooling by sublimation of particles combined with enhanced descent within the rear inflow jet (RIJ) allowed ice particles to survive to temperatures as warm as +6.8°C. In addition, mesoscale descent associated with the RIJ allowed for subsaturated air to persist above and within the melting layer (ML) despite sustained precipitation in the observed regions. Moistening associated with sublimation occurred at a greater rate in the subsaturated air above the ML than the rate of evaporative moistening below the ML due to changes in particle concentrations accompanying increases in particle fall velocity with the phase change across the ML. The environment above the ML moistened between subsequent RIJ spirals, concurrent with maturation of the MCS and closer proximities to the convective line (CL). The effects of aggregation on the temperature dependent microphysical characteristics increased with increasing relative humidity, while the impacts of sublimation on the effects of aggregation and particle shapes, sizes and concentrations became less important. The statistical analysis of 37 PECAN spirals showed that aggregation was common within each of the three MCS regions, with its impacts on the temperature dependent microphysical characteristics the greatest in the enhanced stratiform rain region (ESR), where predominantly ice saturated conditions were found. Progressively smaller changes in particle sizes, shapes, and concentrations due to aggregation were coincident with decreases in the average relative humidity above the ML in the transition zone (TZ) and anvil region (AR). The reverse is true of the impacts of sublimation on the microphysical characteristics of these regions, such that sublimation was most dominant in the AR, where subsaturated conditions persisted to temperatures of −11°C on average and particle number and mass concentrations decreased rapidly with increasing temperature, consistent with a reduced importance of aggregation. Sublimation similarly limited the effectiveness of aggregation within the TZ. Minimal changes with respect to temperature were observed in the microphysical characteristics within the predominantly ice saturated environment of the ESR. The latent cooling imparted with sublimation is thus expected to have been the greatest within the AR, where the descent of the RIJ (if present) would likely initiate. Mesoscale ascent in the stratiform region of a trailing frontal squall line likely contributed to the notably different microphysical characteristics observed within two spirals. These exhibited increasing total number and mass concentrations with increasing temperature along with a high incidence of pristine ice crystals, characteristics absent within all other PECAN spirals.
Scholarship
Creator
Description