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Title: AUTOMATION OF ULTRASONIC FLAW DETECTION APPLICATIONS USING DEEP LEARNING ALGORITHMS
Creator: Virupakshappa, Kushal
Date: 2021
Description: The Industrial Revolution-4.0 promises to integrate multiple technologies including but not limited to automation, cloud computing, robotics,...
Show moreThe Industrial Revolution-4.0 promises to integrate multiple technologies including but not limited to automation, cloud computing, robotics, and Artificial Intelligence. The non-Destructive Testing (NDT) industry has been shifting towards automation as well. For ultrasound-based NDT, these technological advancements facilitate smart systems hosting complex signal processing algorithms. Therefore, this thesis introduces the effective use of AI algorithms in challenging NDT scenarios. The first objective is to investigate and evaluate the performance of both supervised and unsupervised machine learning algorithms and optimize them for ultrasonic flaw detection utilizing Amplitude-scan (A-scan) data. Several inferences and optimization algorithms have been evaluated. It has been observed that proper choice of features for specific inference algorithms leads to accurate flaw detection. The second objective of this study is the hardware realization of the ultrasonic flaw detection algorithms on embedded systems. Support Vector Machine algorithm has been implemented on a Tegra K1 GPU platform and Supervised Machine Learning algorithms have been implemented on a Zynq FPGA for a comparative study. The third main objective is to introduce new deep learning architectures for more complex flaw detection applications including classification of flaw types and robust detection of multiple flaws in B-scan data. The proposed Deep Learning pipeline combines a novel grid-based localization architecture with meta-learning. This provides a generalized flaw detection solution wherein additional flaw types can be used for inference without retraining or changing the deep learning architecture. Results show that the proposed algorithm performs well in more complex scenarios with high clutter noise and the results are comparable with traditional CNN and achieve the goal of generality and robustness.
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Title: Alignment of Science-Themed Trade Books to the Next Generation Science Standards
Creator: Shepard, Kelly Marie
Date: 2021
Description: Elementary teachers often integrate science-themed trade books into their science and reading lessons. This study examines the alignment of...
Show moreElementary teachers often integrate science-themed trade books into their science and reading lessons. This study examines the alignment of science-themed trade books written for readers in Kindergarten through fifth-grade to the Next Generation Science Standards Disciplinary Core Ideas (NGSS DCI). The goal of this research is to analyze the scientific concepts presented in the text of the trade books recommended by professional organizations dedicated to science and science education. Research finds that integrated science and reading are valuable for elementary students’ understandings of science. This study addresses two problems: 1) elementary teachers have limited scientific knowledge and 2) there is a dearth of research that examines the expression of NGSS DCI in science-themed trade books for K-5th grades. The sample is selected from booklists compiled by professional organizations devoted to science and science education. A deductive content analysis methodology is used to identify the presence of NGSS DCI in trade books. Descriptive statistics and qualitative data analyses are used to reveal the themes in the collected data. A large majority of the sample is aligned to the NGSS DCI for K-5th grade. Most trade books express NGSS DCI at the grade levels for which they are recommended. The study is limited and does not examine the readability of trade books, scientific vocabulary, or images. This study contributes to the research on the intersection between science and reading for elementary grade levels.
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Title: DEVELOPMENT OF BIOMARKERS OF SMALL VESSEL DISEASE IN AGING
Creator: Makkinejad, Nazanin
Date: 2021
Description: Age-related neuropathologies including cerebrovascular and neurodegenerative diseases play a critical role in cognitive dysfunction, and...
Show moreAge-related neuropathologies including cerebrovascular and neurodegenerative diseases play a critical role in cognitive dysfunction, and development of dementia. Designing methodologies for early prediction of these diseases are much needed. Since multiple pathologies commonly coexist in brains of older adults, clinical diagnosis lacks the specificity to isolate the pathology of interest, and gold standard is determined only at autopsy. Magnetic resonance imaging (MRI) provides a non-invasive tool to study abnormalities in brain characteristics that is unique to each pathology. Utilizing ex-vivo MRI for brain imaging proves to be useful as it eliminates two important biases of in-vivo MRI. First, no additional pathology would develop between imaging and pathologic examination, and second, frail older adults would not be excluded from MRI.Hence, the aims of this dissertation were two-fold: to study brain correlates of age- related neuropathologies, and to develop and validate classifiers of small vessel diseases by combining ex-vivo MRI and pathology in a large community cohort of older adults. The structure of the project is as follows.First, the association of amygdala volume and shape with transactive response DNA-binding protein 43 (TDP-43) pathology was investigated. Using a regularized regression technique, higher TDP-43 was associated with lower amygdala volume. Also, shape analysis of amygdala showed unique patterns of spatial atrophy associated with TDP-43 independent of other pathologies. Lastly, using linear mixed effect models, amygdala volume was shown to explain an additional portion of variance in cognitive decline above and beyond what was explained by the neuropathologies and demographics.Second, the previous study was extended to analyze other subcortical regions including the hippocampus, thalamus, nucleus accumbens, caudate, and putamen, and was also conducted in a larger dataset. The results showed unique contribution of TDP-43, neurofibrillary tangles (hallmark characteristic of Alzheimer’s disease pathology), and atherosclerosis (a cerebrovascular pathology) to atrophy on the surface of subcortical structures. Understanding the independent effects of each pathology on volume and shape of different brain regions can form a basis for the development of classifiers of age-related neuropathologies.Third, an in-vivo classifier of arteriolosclerosis was developed and validated. Arteriolosclerosis is one of the main pathologies of small vessel disease, is associated with cognitive decline and dementia, and currently has no standard biomarker available. In this work, the classifier was developed ex-vivo using machine learning (ML) techniques and was then translated to in-vivo. The in-vivo classifier was packaged as a software called ARTS, which outputs a score that is the likelihood of arteriolosclerosis when the required input is given to the software. It was tested and validated in various cohorts and showed to have high performance in predicting the pathology. It was also shown that higher ARTS score was associated with greater cognitive decline in domains that are specific to small vessel disease.Fourth, motivated by current trends and superiority of deep learning (DL) techniques in classification tasks in computer vision and medical imaging, a preliminary study was designed to use DL for training an ex-vivo classifier of arteriolosclerosis. Specifically, convolutional neural networks (CNNs) were applied on 3 Tesla ex-vivo MR images directly without providing prior information of brain correlates of arteriolosclerosis. One interesting aspect of the results was that the network learnt that white matter hyperintense lesions contributed the most to classification of arteriolosclerosis. These results were encouraging, and more future work will exploit the capability of DL techniques alongside the traditional ML approaches for more automation and possibly better performance.Finally, a preliminary classifier of arteriolosclerosis and small vessel atherosclerosis was developed since the existence of both pathologies in brain have devastating effects on cognition. The methodology was similar to the one used for development of arteriolosclerosis classifier with minor differences. The classifier showed a good performance in-vivo, although the testing needs to be assessed in more cohorts.The comprehensive study of age-related neuropathologies and their contribution to abnormalities of subcortical brain structures offers a great potential to develop a biomarker of each pathology. Also, the finding that the MR-based classifier of arteriolosclerosis showed high performance in-vivo demonstrate the potential of ex-vivo studies for development of biomarkers that are precise (because they are based on autopsy, which is the gold standard) and are expected to work well in-vivo. The implications of this study include development of biomarkers that could potentially be used in refined participant selection and enhanced monitoring of the treatment response in clinical drug and prevention trials.
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Title: HIGH SURFACE AREA CARBONS FOR ENERGY STORAGE TECHNOLOGIES
Creator: Lee, Youngjin
Date: 2021
Description: Energy storage systems play a pivotal role in harvesting energy from various sources and converting it to the energy forms required for...
Show moreEnergy storage systems play a pivotal role in harvesting energy from various sources and converting it to the energy forms required for applications in several sectors, such as utility, industry, building and transportation. The outstanding growth of portable electronic devices and electric vehicle/hybrid electric vehicles (EVs/HEVs) has promoted the urgent and increasing demand for high‐power energy resources. The most common electrical energy‐storage device is the battery due to the large amount of energy stored in a relatively small volume and weight while providing suitable levels of power for many applications and requirements of everyday life. These days, lithium-sulfur batteries (LSBs) have been drawing attention with their potential to provide 3-5 times more energy than that of current lithium-ion batteries (LIBs) at lower cost. Thus, realization of a practical Li-S technology can move the U.S. rapidly toward a more sustainable transportation future. The electrochemical double-layer capacitor (EDLC) is also an emerging technology, which really plays a key part in fulfilling the demands of electronic devices and systems, for present and future. The EDLC technology strongly depends on the properties of electrode materials. Activated carbons play an important role in developing new electrodes for both LSB and supercapacitor technologies. For example, carbon electrode-based supercapacitors require very high specific surface area and superior pore size distribution for easy accessibility of ions. Thus, the primary objective of this study is to develop a new high surface area carbon material and assess its applicability for both LSB and supercapacitor technologies. In this thesis work, we have designed and synthesized several active carbon materials. One of them displayed very high surface area (1,832 m2/g) and excellent pore diameter (3.6 nm). We investigated the applicability of this carbon material for supercapacitor electrodes. We have also modified this carbon material with a nickel-rich phosphide in order to make it suitable for LSB cathode applications.
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Title: ENERGY METABOLISM OF CHLAMYDIA PNEUMONIAE
Creator: McMillan, B. Julia
Date: 2021
Description: Chlamydia pneumoniae is a gram-negative bacterium that infects the humanrespiratory tract. It causes acute pneumonia and has been linked to...
Show moreChlamydia pneumoniae is a gram-negative bacterium that infects the humanrespiratory tract. It causes acute pneumonia and has been linked to several chronic diseases including cardiovascular disease, asthma, and some neurological diseases. C. pneumoniae primarily exists in two forms, the elementary body (EB) and the reticulate body (RB). The EB infects host cells and the RB replicates inside them. In order to survive in and out of the host, it was thought that C. pneumoniae RBs obtain host ATP to use for energy, making it an “energy parasite.” However, genomic analysis indicated that it was also possible for C. pneumoniae to create ATP from its own respiratory chain using the Na + pump NADH Ubiquinone Oxidoreductase (Na + -NQR). Neither the details of the energy parasite theory nor the possibility of C. pneumoniae creating its own energy had been experimentally explored. This project used a pharmacological approach to explore C. pneumoniae host energy consumption at various developmental stages, examine a mechanism that the bacterium could use to produce its own energy, and assess the importance of a balanced Na + /H + gradient for energy production and maintaining homeostasis. Based on the genomic analysis, it was thought that C. pneumoniae would rely heavily on host ATP in the EB form but not the RB form, that inhibiting Na + -NQR would slow bacterial growth, particularly in RBs, and that disrupting the Na + /H + gradient would significantly reduce RB infection. The results indicate that in the EB form, C. pneumoniae relies on host ATP and requires a balanced Na + /H + gradient, but disrupting Na + -NQR does not hinder its growth. In the RB form, C. pneumoniae is not dependent on host ATP, nor on its own respiratory chain ATP, and is not impacted by an unbalanced Na + /H + gradient. Therefore, the energy parasite hypothesis appears to apply to C. pneumoniae EBs but not RBs. Furthermore, established C. pneumoniae infections are excellent at compensating for various environmental conditions and sources of energy, which proves challenging for drug design against C. pneumoniae.
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Title: The Public Stigma of Tourette Syndrome
Creator: Tooley, Anastasia Cherise
Date: 2021
Description: There is a dearth of quantitative research examining the public stigma of Tourette syndrome (TS), and no known studies assessing public...
Show moreThere is a dearth of quantitative research examining the public stigma of Tourette syndrome (TS), and no known studies assessing public perceptions of difference (how similar they are), disdain (how bad they are), and blame (how responsible they are) toward individuals with TS. The current study sought to understand the public stigma of TS as a visible and unconcealable condition. An internet sample of 450 adults were recruited through MTurk. Participants read four brief vignettes, each describing an adolescent with TS, obsessive-compulsive disorder (OCD), autism spectrum disorder (ASD), or a history of juvenile detention. Results showed TS to be associated with neutral or negative public perceptions across stigma facets. When compared to OCD and ASD, vignettes describing TS were viewed with similar difference, disdain, and blame. TS was least familiar to participants. Findings highlight differences in stigma for concealable versus visible stigmatized conditions which has implications for future research and anti-stigma interventions.
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Title: Examining Racial Differences in Body Dissatisfaction and Disordered Eating Following Media Exposure of a Curvaceous Body Ideal
Creator: Dorsaint, Talissa
Date: 2021
Description: Previous research has found that internalization of a thin body ideal contributes to negative cognitive and behavioral symptoms, such as body...
Show morePrevious research has found that internalization of a thin body ideal contributes to negative cognitive and behavioral symptoms, such as body dissatisfaction and disordered eating. However, studies supporting a sociocultural model have typically included mostly White samples. Research suggests that there may be racial differences in body dissatisfaction and disordered eating among Black and White women, specifically that Black women may be protected from body dissatisfaction via the buffering hypothesis. However, studies have found that differences in body dissatisfaction between Black and White women are smaller than previously thought. Additionally, Black women do not feel represented in the mainstream media on the basis of their physical appearance and ascribed ideals when exposed to thin ideals. Research is needed to examine the impact of other ideals (e.g., the curvaceous body ideal) on body dissatisfaction, as well as body dissatisfaction for Black women in Western culture. The present study used an experimental design to examine differences in body dissatisfaction and disordered eating behaviors in a community sample of Black and White self-identified women before and after exposure to a thin or curvaceous body ideal. Participants were randomized to a thin ideal or curvaceous ideal condition. All participants completed a demographic questionnaire, baseline measures of body dissatisfaction and disordered eating and Visual Analog Scales before and after viewing thin or curvaceous images. Findings indicated no racial differences in baseline body dissatisfaction and disordered eating. Additionally, associations between baseline body dissatisfaction and disordered eating were significant and align with previous research, but an effect of condition was found on body satisfaction change scores. No statistically significant interaction was found between race and body ideal condition for body dissatisfaction change scores. Finally, change scores of body dissatisfaction measures were not statistically different from pre- to post-exposure of either thin or curvy body ideal conditions. Findings have significant implications for the buffering hypothesis and add to studies that have found small racial differences in body dissatisfaction. Present findings also have implications for assessment and treatment in overall eating pathology as seen by the Sociocultural Model in Black women.
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Title: Computational study on the heme scavenging ability of Staphylococcus aureus IsdH receptor: Utilizing molecular dynamics to understand an unknown mechanism
Creator: Clayton, Joseph Alan
Date: 2021
Description: Methicillin-resistant Staphylococcus aureus (MRSA) has become an infamous pathogen with infection rates that have declined slowly in recent...
Show moreMethicillin-resistant Staphylococcus aureus (MRSA) has become an infamous pathogen with infection rates that have declined slowly in recent years. S. aureus requires iron as a metabolic nutrient during infection and obtains this nutrient through an iron-regulated surface-determinant (Isd) system that extracts iron from the host’s heme stored in hemoglobin (Hb) through near iron transporter (NEAT) domains. This work concentrates on studying the second and third NEAT domains of IsdH by utilizing atomistic molecular dynamics to probe the heme scavenging process; in collaboration with the Clubb Group at UCLA, we discover key functional regions of IsdH and describe fundamental interdomain dynamics. In addition, I investigate a conventional computational method to describe protein dynamics and propose an alternative that aims to alleviate computational effort by incorporating experimental data.
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Title: ADVANCING OPEN-SOURCE TOOLS FOR INDOOR ENVIRONMENTAL MONITORING AND BUILDING SYSTEMS CONTROLS USING WIRELESS SENSOR NETWORKS
Creator: Ali, Akram Syed
Date: 2021
Description: Incorporating data monitoring and visualization tools in buildings can provide a glimpse into their energy use, thermal performance, daily...
Show moreIncorporating data monitoring and visualization tools in buildings can provide a glimpse into their energy use, thermal performance, daily operation, and maintenance requirements. However, buildings have traditionally been monitored using hardware and software that are expensive, proprietary, and often limited in terms of ease of use and flexibility. Many existing buildings remain unmonitored or poorly monitored, leaving many opportunities for energy savings and improving indoor environmental conditions unaddressed. To this end, the goal of this research is to develop and demonstrate an open-source hardware and software platform for monitoring and controlling the performance of buildings and their systems, called Elemental. It is designed to provide real-time data on indoor environmental quality, energy usage, heating, ventilating, and air-conditioning (HVAC) operation, and other factors to its users, and provide easy development of building controls. It combines: (i) custom low power printed circuit boards (PCBs) with RF transceivers for wireless sensors, control nodes, and USB gateway, (ii) a Raspberry Pi with custom firmware acting as a backhaul, and (iii) custom software applications that manage data storage, device configuration and interface for querying and visualizing the data in real-time. The platform is built around the idea of a private, secure, and open technology for the built environment. Among its many applications, the platform allows occupants to investigate anomalies in energy usage, environmental quality, and thermal performance. It also includes multiple frontends to view and analyze building activity data, which can be used directly in building controls. This proposal describes the development process of the hardware and software used in the Elemental platform along with three distinct applications including: (1) deployment in a research lab for long-term data collection and automated analysis, (2) use as a full-home energy and environmental monitoring solution, and (3) building heating system automation at the room-level with the development and deployment of a custom radiator control. Through these applications, this work demonstrates that the platform allows easy and virtually unlimited datalogging, monitoring, and analysis of real-time sensor data with low setup costs. Low-power sensor nodes placed in abundance in a building can also provide precise and immediate fault-detection, allowing for tuning equipment for more efficient operation and faster maintenance during the lifetime of the building.
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Title: A Reasoning System Architecture for Spectrum Decision-making
Creator: Das, Udayan D.
Date: 2021
Description: Spectrum is a public resource; yet understanding how spectrum is allocated and used is a daunting task. Usable spectrum is already fully...
Show moreSpectrum is a public resource; yet understanding how spectrum is allocated and used is a daunting task. Usable spectrum is already fully allocated, but the demand for spectrum continues to grow and there are opportunities for utilizing spectrum in more efficient ways. Understanding how spectrum is allocated and its utilization in time and space is necessary to take advantage of these emerging opportunities. A combination of fragmented information from varied information sources, a complex regulatory environment, variability of regulations and physics by band, real-time spectrum usage dynamics, and a status quo with knowledge concentration among a few, makes understanding spectrum a considerable challenge for all stakeholders including researchers, students, policymakers, and new telecom operators. After considerable study of spectrum, its allocation, regulation, and usage, we have developed a system architecture that is a significant step towards easing the burden of understanding spectrum information. Our system architecture connects information from disparate sources and leads to a richer understanding of spectrum usage, how it is governed, and its potential for future use. Classes of information are modeled as knowledge graphs, and the interplay of knowledge graphs produces a richer set of insight and can lead to more informed decision-making. Further, we show mechanisms for connecting spectrum information with real-time observations to get a comprehensive view of spectrum usage dynamics. While focused on the United States, this work should be applicable to other spectrum contexts worldwide. This work, of considerable technical value, also has democratic value in making complex information accessible and allowing the public to determine whether spectrum, a natural resource, is being used for the public good.
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Title: ELECTROCHEMICAL BEHAVIOR OF ADDITIVELY MANUFACTURED NON-SPHERICAL TI-6AL-4V POWDER IN 3.5 WT. % NACL SOLUTION
Creator: Bagi, Sourabh Dilip
Date: 2021
Description: In laser powder bed fusion (LPBF), also known as selective laser melting (SLM), the feedstock powder and processing parameters affect the...
Show moreIn laser powder bed fusion (LPBF), also known as selective laser melting (SLM), the feedstock powder and processing parameters affect the properties of additively manufactured parts. Limited research has been conducted on non-spherical Ti6Al4V feedstock powder prepared by Hydride-Dehydride process. Significant progress in metal powder additive manufacturing (AM) requires the inter-linking of multiple variables, which includes starting materials, process settings, and post-treatment to achieve desired resultant properties. Owing to the rapid emergence of metal 3D-printing, process-property relationships, and appropriate post-treatment conditions have not been as extensively characterized as for conventional materials, thus requiring significant attention. Over the years, spherical powders were used in powder bed AM machines and there have been various concerns related to powder as well as processing parameters leading to defects formation, poor part quality, and unsatisfactory performance. It is critical to keep the cost of manufacturing low for large-scale production which results in significant interest in low-cost powder, making it vital to understand the effect of microstructural defects on corrosion behavior. Recently, economical powder attracted attention in AM, thus, making it is necessary to understand the role of possible microstructural defects on corrosion behavior. In powder bed additive manufacturing, feedstock and processing affect final microstructure and properties of the 3D printed parts. While numerous studies have evaluated 3D-printing of spherical powder, very limited research has examined the processing of the non-spherical feedstock. In this research, parts are manufactured by SLM of hydride-dehydride (HDH) Ti6Al4V powder. heat treatment and hot isostatic pressing are applied on SLM parts. The microstructures, potentiodynamic curves, and electrochemical impedance spectroscopy are characterized for SLM processed, heat treated, and hot isostatically pressed HDH Ti6Al4V specimens. Results indicate although the as-built specimen has anisotropic microstructure (i.e., lamellar α + acicular α’ + β phases), the heat treatment and hot isostatic pressing result in homogenized grain structures and enhanced corrosion behavior. Results indicate that type of constituent phase, grain size, and morphology directly determine corrosion resistance. This research is beneficial for the manufacturing of low-cost titanium alloys. In the current research, we evaluate non-spherical powder processing by hydride-dehydride (HDH) method and selective laser melted in powder bed AM machine followed by heat treatment and hot isostatic pressing to alter microstructure and electrochemical behavior. If successful, the usage of non-spherical morphology in conjunction with the newer powder dispensing method of double smoothing will enable remarkable improvements in the quality and performance of additively manufactured products. This method will also cut down costs associated with a greener powder production method and enhance the fabrication rate. It is a well-established fact that corrosion behavior is drastically affected by heterogeneous microstructure and defects. Thus, it is paramount to conduct a systematic study on the role of processing parameters and post process heat treatment, which can enhance our understanding of possible defect formation in micro and macro scale and their impact on electrochemical behavior.
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Title: OPTIMUM WEIGHT STIFFNESS STRUCTURAL DESIGN
Creator: Barnett, Ralph L.
Date: 2021
Description: My adventures with flexible structures began on the IIT campus with an extracurricular undergraduate project to design an “Open House Exhibit”...
Show moreMy adventures with flexible structures began on the IIT campus with an extracurricular undergraduate project to design an “Open House Exhibit” for the Civil Engineering Department. I chose to display a reinforced concrete diving board together with a prestressed concrete diving board. Visitors enthusiastically pounced on the reinforced concrete structure whose rigid response disappointed one and all. Their indignation was transferred to the prestressed cantilever which thrust them upward from six to ten feet into the air. This unexpected response from a diving board became so dangerous that the Exhibit was unceremoniously closed. I still have the display sign, “More Bounce to the Ounce.”While still an undergraduate, I secured a part-time job at Armour Research Foundation where I responded to a bid request from Rock Island Arsenal to design the 26 foot Honest John Rocket Launcher Rail at minimum weight. This tactical weapon was transported by helicopter. I basked in the fantasy that I was Leonardo da Vinci without his artistic proclivity. Rocket launchers that droop during operation are similar in concept to a circular firing squad. So began my research into minimum weight beams based on deflection rather than strength. I searched for the shoulders of Giants. I found them in the form of mathematicians not structural engineers. I achieved a 26.5% weight savings in the 1126 pound rail by optimizing the geometry. When I developed an optimum prestressed and segmented Kentanium cermet rail, the weight savings became 89%. The right material provides a bigger bang for the buck. When my journey into optimum design began, I was armed only with analysis tools: strength, stability, and stiffness. This thesis begins with an outline of my present toolbox which contains eight design concepts: 1. Establish the Geometry, 2. Select a material from a finite number of candidates, 3. Prestress and Prestrain, 4. Statistical Screening (Proof Testing), 5. Manipulation of Boundary Conditions, 6. Energized Systems, 7. Counterweights, 8. Self-Healing and Self-Reinforcing. Four of these are used through this review which focuses on stiffness. Beginning with beams, deflection control examples are described where prestraining and prestressing techniques are used to produce both a zero-deflection beam and a method for pushing with a chain. The calculus of variations made it possible to establish optimum tapers for the flanges and webs of I-beams that minimize beam weight for a specified deflection or, because of reciprocity, minimize beam deflection for a specified beam weight. An anomaly is encountered that enables one to achieve an upward, downward, or zero deflection with a set of beams of vanishing weight. In addition, special circumstances are defined where a uniform strength design is identical to the minimum weight design based on a specific deflection. Closed form solutions are obtained for a variety of loading scenarios. One problem is presented for self-weight that leads to a nonlinear integral equation. The optimum stiffness-weight design of trusses is undertaken where the area distribution of the truss members is optimized using Lagrange’s method of undetermined multipliers. Once again, we obtain a degenerate case where upward, downward, and zero deflection conditions can be met with an infinite set of trusses of vanishing weight. We photograph a simply supported truss under a downward load that leads to an upward deflection at one of the joints. Special loading conditions are identified that lead to uniform stress designs that are identical to the minimum weight designs based on deflections. This study provides a Segway into the world of minimum weight strength design of trusses. The resulting Maxwell and Michell trusses sometimes display the optimum distribution of bar areas from the point of view of stiffness. Many practitioners are under the mistaken impression that Michell structures, when they exist, provide the optimum truss profile for stiffness. Unfortunately, the optimum array of truss joints based on deflection does not exist. For both trusses and beams the optimum distribution of mass is shown to be necessary and sufficient; the sufficiency is established using well-known inequalities. The role of stiffness in the design of columns is explored in our final chapter. This cringe-worthy history of column analysis begins our study as a warning to practitioners who use analysis as their basis for design and especially optimum design. Conventional elastic and inelastic buckling theories provide little insight into the design of columns. The fundamentals of minimum weight column design are presented to show the power of design theory in contrast to analysis. Both prismatic and tapered columns are studied with one surprise result; the optimum taper gives rise to a uniform bending stress (without axial stresses). It was fun to see that in 1733 Lagrange made a mistake in calculus of variations that led to the incorrect solution for the optimum tapered column. It took 78 years before Clausen obtained the correct solution. The problem has been revisited by William Prager and again by the author who used dynamic programming. Of course, we all got the same result which is a dreadful solid circular tapered column that is heavier than any ordinary waterpipe. The best of a class is not necessarily the best possible design. Under the heading, “Intuition is a good servant but a bad master,” we introduce the notions of tension members that buckle, columns constructed from spherical beads, optimum rigging of crane booms, and deflection reversal of beam-columns. In several places we observe that the weight of optimum columns is proportional to P^α where P is the axial load and α is less than unity. We fail to tell the reader that this implies that minimum weight columns require putting all your eggs in one basket; one column under load P is lighter than two columns each under load P/2. On the other hand, we expose the solid circular column as the least efficient shape among all regular polygons, the equilateral triangle is the best. Indeed, there is a family of rectangles that are superior to the circular cross-section. Finally, the author’s prestressed tubular column is introduced that is pressurized to eliminate local buckling. Euler’s buckling can always be eliminated with a thin-wall section of sufficient width without a weight penalty. The weight of the balloon-like member is proportional to (PL) which implies that at last we have a compressive member that meets the requirement of a Michell structure. Bundling of pressurized gas columns are possible without a weight penalty. Further, the column is insensitive to most imperfections. It is the lightest known column for small structural indices (P/L^2 ). When coupled with circulating cryogenic liquid as a prestressing system, a limiting column has a vanishing weight.
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Title: The Relation Between Executive Functions and Academic Performance in Clinically-Referred Adolescents
Creator: Coultis, Nora Plumb
Date: 2021
Description: The literature on executive functioning (EF) and academic performance has focused on early academic performance in young children (Best et al....
Show moreThe literature on executive functioning (EF) and academic performance has focused on early academic performance in young children (Best et al., 2011). Few studies have assessed the relation between EF abilities and academics in adolescents, which is particularly important because the demand on EF skills greatly increases in middle and high school (Best et al., 2011). Environmental factors, including completing multiple assignments, managing increased independent work, and changing classes, exacerbate the EF burden and reduce cognitive resources (Langberg et al., 2013; Samuels et al., 2016). Academic tasks also become more complex during middle and high school, for example, requiring solving algebraic problems, reading comprehension, and expository writing (Bull & Scerif, 2001; Sesma et al., 2009). Thus, complex academic tasks in adolescence likely require a higher demand on EF abilities compared to academic tasks in early childhood. The extant literature also has several limitations, such as focusing on only a couple of EF or academic domains and using parent- or teacher-report ratings rather than performance measures. Therefore, the aim of this study was to examine the relation between four domains of EF (i.e., working memory, inhibition, shifting, and planning) and three areas of academic performance (i.e., reading, writing, math) in a sample (N = 87) of clinically-referred middle and high school students. Contrary to expectation, results of hierarchical multiple regression analyses revealed that the measures of EF did not contribute significant additional variance to scores in reading and writing performance after controlling for IQ. It is notable that the EF variables did contribute a significant amount of additional variance to math scores after controlling for IQ and diagnosis. However, only working memory was significantly associated with math performance. This finding suggests that strategies designed to enhance working memory may be effective in improving math performance in students who are underperforming.
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Title: Assessment of Sleep Characteristics and Their Effects in People with Type 1 Diabetes for the Development of a Sleep Module for the Multivariable Artificial Pancreas System
Creator: Brandt, Rachel
Date: 2021
Description: his work is focused on the relationship between sleep and blood glucose control in people with Type 1 Diabetes and on the development of a...
Show morehis work is focused on the relationship between sleep and blood glucose control in people with Type 1 Diabetes and on the development of a sleep module incorporating new variables and rules for use in automated insulin delivery and advisory systems. Through this research, sleep effects were identified, quantified and incorporated into a multivariable artificial pancreas system (mvAP) that is currently being developed. The mvAP uses different physiological signals acquired through non-invasive wearable sensors along with a continuous glucose monitor (CGM) to detect the state of the user to predict future blood glucose values to aid in insulin dosing decisions. The overall objective of the research was to develop and add a module to further improve the successful mvAP by incorporating sleep related information while retaining the functionality and safety of the system and improving the effectiveness in maintaining good glycemic control. Two types of sleep effects were studied: effects of sleep characteristics and stages in real-time (during sleep) and effects of sleep on glucose metabolism the next day. It was found that poor sleep quality was related to higher glycemic variability overnight in adults with Type 1 Diabetes. However, in adults without diabetes, there were no consistent relationships found between sleep stages and changes in blood glucose levels overnight. For adults with Type 1 Diabetes, it was determined that Sleep Quality, Total Sleep Time, Wake After Sleep Onset (WASO), Number of Awakenings >5 minutes, and amount of Deep sleep could be used in conjunction with insulin on board and the amount of time that has passed since the user has woken up to predict how much more insulin may be needed at the first meal of the day. This Insulin Multiplier Algorithm was tested and validated in replay simulations. Finally, in order to incorporate these relationships into the mvAP, a sleep stage detection algorithm was developed using the Empatica E4 wristband.
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Title: BURNOUT AMONG SEXUAL MINORITIES: THE ROLE OF CONCEALMENT, RUMINATION, AND ORGANIZATIONAL NON-DISCRIMINATION POLICIES
Creator: Burke, Margaret
Date: 2021
Description: Employee burnout is detrimental to individuals (e.g., physical and mental health concerns), as well as to organizations (e.g., diminished...
Show moreEmployee burnout is detrimental to individuals (e.g., physical and mental health concerns), as well as to organizations (e.g., diminished performance). Although numerous studies have examined burnout across a variety of industries and populations, there are limited studies that have examined burnout specifically among sexual minority employees, referring to lesbian, gay, bisexual, transgender, and queer (LGBTQ) workers. This study integrated Meyer’s (2003) Minority Stress Model and Hatzenbuehler’s (2009) Psychological Mediation Framework to investigate the role of concealment, rumination, and non-discrimination organizational policies on burnout among 406 sexual minority employees working in a variety of industries (e.g., healthcare, retail, education, etc.). To test the relationships between these variables, a mediation model and a mediation with moderation model was tested using Hayes’ (2018) Process macro. Results indicated that concealing one’s sexual orientation at work was positively related to rumination, and in turn, was positively related to burnout. Contrary to one of the hypotheses, organizational non-discrimination policies that were inclusive of sexual minorities did not moderate the relationship between concealment and burnout. Previous research, implications, and limitations to this study are discussed in detail.
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Title: TOWARD A MODERN CIVIC MONUMENTALITY: ARCHES, VAULTS, AND DOMES IN POSTWAR AMERICAN ARCHITECTURE
Creator: Amado Petroli, Marcos
Date: 2021
Description: This dissertation studies the use of arcuated structures in post-World War II American civic buildings, which serve both to answer the...
Show moreThis dissertation studies the use of arcuated structures in post-World War II American civic buildings, which serve both to answer the practical and functional demands of the architectural program, and to communicate a distinct and hierarchical character inherent to the very genesis of civic architecture. This research demonstrates how a generation of multicultural architects, educated in the academic tradition, with the collaboration of structural engineers, participated in the expansion of the syntax and vocabulary of modern architecture at a time when the language of monumentality was also being discussed. In doing so, they moved away from a Bauhaus-German doctrine that promoted a universal, orthogonal, and homogeneous architectural language, serving all types of buildings. In this context, this research redefines the relationship between academic tradition and modern approaches to monumentality in American architecture, which are usually seen as antagonistic languages. To test the hypothesis that these new arched forms, of high structural engineering, were linked to both modern and academic aspects, and more precisely, French roots, this research addresses three main issues: (i) the mistrust of the new monumentality, which was often mystified and associated with totalitarian regimes; (ii) the analysis of this production through pioneering case studies in postwar arched structures; and (iii) the relationship between academic tradition and modern architecture, with an emphasis on the theory of "architectural character." Finally, this research concludes that the construction of this civic monumentality in the United States was not only a rational response to special programs and an opposition to the universal character of modern buildings, but also the result of an immigration of more inclusive ideas, which, reacting with the local tradition and heritage of the Beaux-Arts system, gave rise to an autochthonous American production.
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Title: Towards a Self-Programmable Storage Solution in Extreme-Scale Environments
Creator: Devarajan, Hariharan
Date: 2021
Description: Traditional compute-centric scientific discovery has led to a growing gap between computation power and storage capabilities. However, in the...
Show moreTraditional compute-centric scientific discovery has led to a growing gap between computation power and storage capabilities. However, in the data explosion era, where data analysis is essential for scientific discovery, slow storage systems led to the research conundrum known as the I/O bottleneck. Scientists have proposed several optimizations to address the I/O bottleneck. However, selecting and applying the appropriate optimization is a complex task, often left to the users. Additionally, the explosion of data has led to the proliferation of applications as well as storage technologies. This has created a complex matching problem between diverse application requirements and heterogeneous storage resources for the users. We need to move towards a Self-Programmable storage system that can automatically understand the I/O requirements of applications, transparently leverage the heterogeneity of storage, and reconfigures itself dynamically by utilizing application and storage information. In this work, we present the Jal System for building Self-Programmable storage. The Jal System consists of three layers: the application layer, the transfer layer, and the storage layer. The application layer uses automatic extraction of I/O requirements from applications using a source-code-based profiler. The storage layer defines a data abstraction, using a shared log store, to efficiently unify heterogeneous storage resources under a single platform. Finally, the transfer layer defines data management algorithms that consider multi-application and multi-storage information to optimize data operations. Additionally, we illustrate the benefits of utilizing the technologies within the Jal System on modern scientific AI applications. Our evaluations have demonstrated that each technology within the Jal System can accelerate I/O for modern scientific workflows. We have implemented software, tools, and system libraries for modern HPC systems. In the future, we envision building a fully integrated system that efficiently utilizes all the Jal System technologies. Additionally, we plan to extend the strategies and techniques in Jal System to other scientific domains such as AI and IoT.
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Title: IDEOLOGICALLY MOTIVATED INTENTIONAL ADULTERATION: THEORY INTO INDUSTRIAL APPLICATION
Creator: DeVuyst, Adrian Jeffrey
Date: 2021
Description: Ideologically motivated intentional adulteration is an attempt to cause harm to consumers of food. Within the context of the United States of...
Show moreIdeologically motivated intentional adulteration is an attempt to cause harm to consumers of food. Within the context of the United States of America (US), the current methods of addressing this risk are evolving in the modern post-Food Safety Modernization Act (FSMA) era. Currently, the US has the Food and Drug Administration (FDA), which requires companies to have a food defense plan with a risk assessment, mitigation strategies, and recordkeeping. Additional options from Global Food Safety Initiatives (GFSI) benchmarked standards offer additional options for a company. However, even with these standards companies are still being impacted by intentional adulteration. Historical examples from the poisoning of bread in Hong Kong during British occupation and spreading of bacteria on salad bars by the followers of Rajneesh, to more modern examples of putting needles in strawberries and urinating on production equipment show a food defense system that is not always able to address intentional adulteration. The question of why companies are still having intentional adulteration comes up. The lack of food defense events and primary research on the topic creates a system where individual companies must gather data. Evaluations and surveys at a manufacturing site, N=11, indicates that there is high confidence among front line workers about their level of knowledge, but workers are unable to articulate the basic principles of food defense. Each individual company is required to create a personalized food defense system in the status quo, but the results of the survey given suggests that the data they could gather may be insufficient to create an effective food defense system.
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Title: Modeling the Aerodynamic Response to Impulsive Active Flow Control
Creator: Asztalos, Katherine
Date: 2021
Description: In unsteady aerodynamics the response to external disturbances can depend significantly on the initial condition, and the extent to which this...
Show moreIn unsteady aerodynamics the response to external disturbances can depend significantly on the initial condition, and the extent to which this impacts the ability to model the flowfield can vary. In this work, we look to develop a model that can capture and predict the long-time response to actuation, which we suspect to be sensitive to the instantaneous state. We investigate whether a physical understanding of the short-time response to impulsive actuation can be obtained, with the goal of understanding the observed physical phenomenon present in the immediate response to this type of actuation. We find that the response to impulsive actuation is sensitive to the instantaneous wake, and that the short-time response is directly proportional to the time rate of change of the actuation input. Computational simulations of a stalled NACA 0009 airfoil subject to leading-edge synthetic jet actuation were performed. Full state information, as well as force response measurements, were collected using an immersed boundary method (IBM) numerical code. The numerical simulations performed sought to characterize the response to actuation by varying the actuation parameters, such as the strength, direction, and phase at which the onset of actuation occurs. It was found that the long-time response to actuation can be sensitive to the instantaneous wake state at the onset of actuation. The ability to extract models that describe the complex behavior of the system provides additional insight into the dominant features governing the response of such systems, as well as achieves predictive capabilities of the systems' response. The data-driven models, which are identified using variants of dynamic mode decomposition, can capture both the short- and long-time response of the system to actuation. Predictive models are identified using multiple trajectories of data corresponding to varying the phase of vortex shedding at which the onset of actuation occurs. These models achieve accurate predictions for off-design cases as well. It is also shown that multiple control objectives with the same actuator can be achieved. Classical theory aids in understanding the physics governing unsteady aerodynamic motion and the response to disturbances. Theoretical models are developed using the assumptions from classical unsteady aerodynamic theory, which provide insight into the forms that the data-driven models take. The effect of short-duration momentum injection actuation is modeled through a combination of source/sink, doublet, and vortex elements. Regardless of the precise elements used in the theoretical model, the lift response is composed of a contribution directly proportional to the rate of change of actuation strength, and a contribution that persists after the actuation burst ends that arises due to the enforcement of the Kutta condition. Methodologies that retain the physics inherent to the system by projecting the governing equations of motion onto a well-suited basis are extremely valuable for gaining physical insight and understanding into the dynamics of the flowfield. A new methodology is proposed for extracting spectral content from systems with limited data available using projection-based modeling approaches. There are challenges associated with using modal decomposition-based modeling techniques for systems exhibiting large transient dynamics due to external inputs, which is applicable in this particular instance and for related systems. The methodology presented here shows how the dynamics of this system can be understood through analysis of optimal finite-time horizon transient energy growth, applied to reduced-order models identified using actuation response data with either data-driven or physics-based models. A novel methodology is proposed to guide future experimental actuation design to achieve maximal response by considering an optimal forcing mode, identified from considering the optimal perturbation of the full unactuated system, which maximizes a given output.
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Title: Computationally Efficient Predictive Control Strategies for Autonomous Vehicles
Creator: Bhattacharyya, Viranjan
Date: 2021
Description: This thesis aims at developing computationally efficient (hence real-time applicable) control strategies for autonomous vehicles in the...
Show moreThis thesis aims at developing computationally efficient (hence real-time applicable) control strategies for autonomous vehicles in the presence of uncertainty, while incorporating high fidelity vehicle dynamics. The motivation for the control strategies is to ensure safety and improve energy efficiency of the vehicles. In this research, an effort has been made to develop control strategies to strike a balance between these competing factors. The specific contributions are: development of a new hierarchical control framework that can guarantee avoidance of red-light idling in the presence of uncertainty in preceding vehicle information/prediction in connected environment (hence improves system mobility); exploitation of a data-driven modeling approach for identifying a linear predictor for the nonlinear vehicle dynamics, which facilitates formulation of a convex equivalent problem of the original non-convex problem (hence facilitates computational tractability); introduction of a novel vehicle dynamics-aware fast game-theoretic planner for behavior and motion planning of vehicles in uncertain and unconnected environments. This thesis explores both the possible directions of future autonomous vehicles: connected and unconnected autonomous vehicles. In particular, the first problem relates to longitudinal fuel efficient driving (eco-driving) in a connected urban environment, where the connected and automated vehicles (CAVs) aim at the improvement of fuel efficiency and reduction of red-light idling (stop and go motion). The CAVs also focus on ensuring collision avoidance with the preceding vehicles despite the prediction uncertainty in future trajectory of preceding vehicles. This problem assumes vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication, and is a longitudinal control problem. The next problem considers the uncertainty in prediction of future states of neighbouring vehicles in an unconnected environment and involves both lateral and longitudinal control. Following previous research, the interactive nature of driving is modeled using game-theory and a computationally efficient game-theoretic planner is introduced. Simulation results show the efficacy of the proposed methods in terms of computational tractability and fuel-efficiency.
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