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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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Title: CORPORATE SOCIAL RESPONSIBILITY AND SUSTAINABLE ECONOMIC DEVELOPMENT IN CHINA
Creator: Cheng, Weiquan
Date: 2021
Description: This paper examines corporate social responsibility (CSR) strategies and their anticipated impacts on both company’s performance and climate...
Show moreThis paper examines corporate social responsibility (CSR) strategies and their anticipated impacts on both company’s performance and climate change mitigation in mainland China. It performs analysis on the effectiveness of the policies/efforts undertaken by Chinese publicly traded companies to carry on CSR projects through CSR disclosure system, and specifically focuses on determining if CSR projects could help to enhance companies’ profitability while promoting sustainable development in China. It utilizes companies’ financial statements and CSR reports from China Stock Market & Accounting Research Database (CSMAR), and regional macroeconomic data from National Bureau of Statistics of China from 2006 to 2016. The modeling results indicate that industry types, and socioeconomic conditions within which they operate control the anticipated outcome of implementing CSR projects specifically if those projects are designed to reduce companies' carbon emissions. This research provides valuable insights for CSR development in the future according to company types and socioeconomic imbalance in China.
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Title: Evaluation of Bax∆2 Positive-Staining in Skin Samples Using Two Immunohistochemical Methods
Creator: Basheer, Sana
Date: 2021
Description: BaxΔ2 is a pro-death and tumor suppressor protein that sensitizes cells to certain chemotherapies. Previous diaminobenzidine (DAB)-based...
Show moreBaxΔ2 is a pro-death and tumor suppressor protein that sensitizes cells to certain chemotherapies. Previous diaminobenzidine (DAB)-based staining revealed that Bax∆2 is found in all organs, including breast, colon, and skin tissues. In the skin, the Bax∆2 positive cells were mainly found in the basal cell layer of the epidermis with a few Bax∆2 positive cells in the connective tissue of the dermis, although their cellular identity was unknown. Previous literature has shown that melanin, which is found throughout the cells of the epidermis, is a brown color that provides no visual contrast to the DAB staining. While the DAB-based immunostaining showed cells that appeared to be Bax∆2 positive, this result needed to be confirmed. For this, a set of human skin samples from normal and cancerous tissue of various patients was examined. The co-staining of these samples for Bax∆2 and basal cells using immunofluorescence revealed that the apparent Bax∆2-positve DAB staining in epidermal basal cells and squamous cell carcinoma as false-positive, but the Bax∆2 positive cells found in the dermal connective tissue were not false positive—which is consistent with both previous DAB-based and fluorescence-based immunostaining. Using co-immunostaining for Bax∆2 with different cellular markers, the Bax2-positive cells in the connective tissue were identified potentially as macrophages and fibroblasts. Further studies are required to confirm the identity of the Bax∆2 positive cells in the connective tissue.
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Title: WIENER-HOPF FACTORIZATION FOR TIME-INHOMOGENEOUS MARKOV CHAINS AND BAYESIAN ESTIMATIONS FOR DIAGONALIZABLE BILINEAR STOCHASTIC PARTIAL DIFFERENTIAL EQUATIONS
Creator: Cheng, Ziteng
Date: 2021
Description: This thesis consists of two major parts, and contributes to two areas of research in stochastic analysis: (i) Wiener-Hopf factorization (WHf)...
Show moreThis thesis consists of two major parts, and contributes to two areas of research in stochastic analysis: (i) Wiener-Hopf factorization (WHf) for Markov Chains, (ii) statistical inference for Stochastic Partial Differential Equations (SPDEs).WHf for Markov chains is a methodology concerned with computation of expectation of some types of functionals of the underlying Markov chain. Most results in WHf for Markov chains are done in the framework of time-homogeneous Markov chains. The major contribution of this thesis in the area of WHf for Markov chains are: • We extend the classical theory to the framework of time-inhomogeneous Markov chains. • In particular, we establish the existence and uniqueness of solutions for a new class of operator Riccati equations. • We connect the solution of the Riccati equation to some expectations of interest related to a time-inhomogeneous Markov chain. Statistical inference for SPDEs regards estimating parameters of a SPDE based on available and relevant observations of the underlying phenomenon that is modeled by the given SPDE. We summarize the contribution of this thesis in the area statistical inference for SPDEs as follows: • We conduct the statistical inference for a diagonalizable SPDE driven by a multiplicative noise of special structure, using spectral approach. We show that the corresponding statistical model fits the classical uniform asymptotic normality (UAN) paradigm. • We prove a Bernstein-Von Mises type result that strengthens the existing results in the literature. • We prove the asymptotic consistency, asymptotic normality and asymptotic efficiency of two Bayesian type estimators.
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Title: Modeling and Control Methods for Boundary Constrained Soft Robots
Creator: Zhou, Qiyuan
Date: 2021
Description: Soft and deformable robots have been an active field of research in the past few years. However, they are limited in that they cannot apply...
Show moreSoft and deformable robots have been an active field of research in the past few years. However, they are limited in that they cannot apply much force to an environment due to the limitations of the flexible materials from which they are made of. To help overcome this limitation, a new architecture named the Jamming and Morphing Enabled Bot Array (JAMoEBA) system was conceived. This system consists of a flexible outer membrane which encloses an interior composed of a granular medium. Active sub-units along the flexible outer membrane allow for actuation and locomotion of the system. The granular material coupled with the flexible outer membrane allows the robot to maintain the characteristics typically associated with soft robots (continuum, compliant, configurable). At the same time, the granular material is also able to undergo a solid phase transition with the application of pressure to the flexible outer membrane and allow the system to behave more like a rigid robot if needed. This allows for the robot system to exploit the desirable characteristics of both soft and rigid robots in its tasks.The purpose of this thesis is to offer a discussion and demonstration of various simulation methods for the physically accurate modeling of the JAMoEBA constrained boundary robotic system and to show some of the control methods which have been investigated within the selected modeling framework. Simulation methods based on Lennard-Jones (L-J) potentials, non-smooth contact dynamics (NSCD), as well as the discrete element methods based on complementarity (DEM-C) and penalty (DEM-P) conditions as implemented in the open source physics library Project Chrono are considered. Comparisons are made in the areas of physical accuracy, computational efficiency, and feature availability in the consideration of the best simulation method for the JAMoEBA system. Investigations of control strategies such as leader-follower and heuristics based approaches are carried out using the selected simulation method. Finally, a framework for self contained localization which relies on measurements from onboard sensors and linear Kalman filtering is tested within the simulation framework, and the effectiveness of approximating the shape of the JAMoEBA system using elliptical Fourier descriptors is shown.The main contributions made in this thesis are in the areas of suitable modeling methods, controls strategies, and localization techniques for the novel boundary constrained JAMoEBA soft robot architecture. The work done serves as a solid foundation for the future study of this novel soft robotic architecture due to the demonstration of successful methods for modeling, control, and localization of the system. The work presented is not meant to be a comprehensive or deep dive into any one specific area, but rather a jumping off point for future areas of research.
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Title: EFFECTIVENESS OF CLEANING STRATEGIES FOR REMOVING MILK CHOCOLATE FROM PILOT-SCALE PIPE/VALVE ASSEMBLY AND CHOCOLATE PROCESSING EQUIPMENT
Creator: Zhang, Liyun
Date: 2019
Description: Dark chocolate manufactured on shared processing lines with milk chocolate is a high-risk food for consumers with milk allergy. Inadequate...
Show moreDark chocolate manufactured on shared processing lines with milk chocolate is a high-risk food for consumers with milk allergy. Inadequate cleaning of shared chocolate manufacturing equipment can result in milk contamination of subsequent products, and product recalls. Limited information is available on the effectiveness of different cleaning procedures for preventing the transfer of milk to dark chocolate processed on shared equipment. Pilot-scale experiments investigated the effectiveness of three dry cleaning methods: 1) no cleaning, 2) pig purging, and 3) a cocoa butter flush (40°C, 1 hour) for removing milk chocolate residue from a heated (40ºC) standard (1.5” OD) sanitary stainless steel pipe (30.5 cm length) and attached butterfly or ball valve. After cleaning, milk-free dark chocolate (~27 kg, 40°C) was pumped through the pipe/valve combination. Dark chocolate push-through samples were collected and analyzed for milk concentrations with a Neogen Veratox total milk ELISA kit. Experiments with no cleaning resulted in initial milk concentrations up to 6,070 (9.6% CV) ppm milk and up to 14,900 (0.3% CV) ppm milk for the pipe/butterfly valve and the pipe/ball valve, respectively. Cocoa butter recirculation through the pipe/butterfly valve decreased initial milk concentrations to 680 (10.3% CV) – 2720 (2.6% CV) ppm milk. Use of a pig purging dramatically reduced milk levels to 45 (4.3% CV) – 180 (15.7% CV) for the pipe/butterfly valve and below limit of quantification of ELISA (LOQ, 2.5 ppm milk) for the pipe/ball valve. After most cleaning treatments, > 14 kg of dark chocolate push-through was required to obtain milk levels < LOQ.A second set of pilot-scale experiments determined the efficacy of cleaning procedures for removing milk chocolate from selected chocolate processing equipment. Three cleaning methods explored removal of milk chocolate from a ball mill and conche: 1) no cleaning, 2) a cocoa butter flush (40°C, 5 min), and 3) wet cleaning (detergent-rinse-air dry). After cleaning, three batches of milk-free dark chocolate (40°C) were processed in the ball mill (~0.35 kg) and conche (2.5 kg), and each batch was collected and analyzed for milk. Milk chocolate (1.5 kg) was processed on a 3-roll refiner, followed by push-through with dark chocolate (~8 kg), with 0.3 kg samples collected at 5-min intervals. Milk was not detected (Show less

Title: Synthesis and Processing of NaSICON Membranes with High Ionic Conductivity and Good Mechanical Strength
Creator: Chiang, Shan-Ju
Date: 2019
Description: Natrium super ion conductors (NaSICONs), Na1+xZr2SixP3-xO12 (0 ≤ x ≤ 3) are compounds that commonly used as solid electrolytes and membranes...
Show moreNatrium super ion conductors (NaSICONs), Na1+xZr2SixP3-xO12 (0 ≤ x ≤ 3) are compounds that commonly used as solid electrolytes and membranes of sodium based batteries, or in gas sensors and fuel cells due to their high sodium ion conductivity, low thermal expansion, and ability to accommodate ions in the lattice. However, NaSICON with high relative density (> 97%) and minimum impurity phases is found to be very difficult to obtain. Furthermore, the cost of the general synthesis methods is a serious drawback. Multi-high-temperature heating procedures is often employed to increase the density and to attain the single phase NaSICON because the particle size and free ZrO2 are better reduced. This research explores the possibility of densification and synthesis of NaSICON in one high-temperature reaction through a novel process termed Integrated Mechanical and Thermal Activation (IMTA) and the co-sintering behavior as well as the NaSICON composite membranes from tape casting. The sintering temperature of NaSICON was decreased by mechanical activation at room temperature using high-energy ball milling. Sintered NaSICON-based materials showed highest total ionic conductivity of 1.45 × 10-3 S cm-1 at room temperature and high density of 3.155 g cm-3 (96.5%). An alternative to obtaining full densification (99%) of NaSICON ceramics was developed utilizing traditional solid-state reaction. This sintered NaSICON without any sintering aid exhibited the total conductivity, 6.59 × 10-4 S cm-1 at 25 °C, and the highest density of 3.238 g cm-3, a better than 2.6% enhancement from the original samples.The second part of the work has comprised of successful fabrication of NaSICON/polymer composite membranes and bi-layered NaSICON/stainless steel membranes to enhance the mechanical flexibility of pure NaSICON films. The effect of different particle sizes of stainless steel on the sintering behavior and shrinkage rate were studied systematically. The effect of solid content in the slurry was also studied to control the density of both support layer and NaSICON body. The affect structural ratios have on co-sintered tapes along with ionic conductivity was investigated using Electrochemical Impedance Spectroscopy (EIS). The co-sintered membrane exhibited a total conductivity as high as 4.580 × 10-4 S/cm at room temperature. EIS results showed the high Na-ions conductivity strongly depends on the feature of grain boundary and the high densification of NaSICON layer.
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Title: An aircraft hangar and the study of long-span metal structures
Creator: Sharpe, David C. (David Carold)
Date: 1962-06
Description: The study of long-span structures developed from a design problem for an aircraft hangar. The problem of the aircraft hangar was concerned...
Show moreThe study of long-span structures developed from a design problem for an aircraft hangar. The problem of the aircraft hangar was concerned with the development of a reasonable structurtal type into an architectural solution. Several types were considered; the truss, the arch, a rigid frame system in prestressed concrete. These were discarded in favor of a rigid frame system of steel that seemed to give the best visual solution.
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Title: Advances in Machine Learning: Theory and Applications in Time Series Prediction
Creator: London, Justin J.
Date: 2021
Description: A new time series modeling framework for forecasting, prediction and regime switching for recurrent neural networks (RNNs) using machine...
Show moreA new time series modeling framework for forecasting, prediction and regime switching for recurrent neural networks (RNNs) using machine learning is introduced. In this framework, we replace the perceptron with an econometric modeling unit. This cell/unit is a functionally dedicated to processing the prediction component from the econometric model. These supervised learning methods overcome the parameter estimation and convergence problems of traditional econometric autoregression (AR) models that use MLE and expectation-maximization (EM) methods which are computationally expensive, assume linearity, Gaussian distributed errors, and suffer from the curse of dimensionality. Consequently, due to these estimation problems and lower number of lags that can be estimated, AR models are limited in their ability to capture long memory or dependencies. On the other hand, plain RNNs suffer from the vanishing and gradient problem that also limits their ability to have long-memory. We introduce a new class of RNN models, the $\alpha$-RNN and dynamic $\alpha_{t}$-RNNs that does not suffer from these problems by utilizing an exponential smoothing parameter. We also introduce MS-RNNs, MS-LSTMs, and MS-GRUs., novel models that overcome the limitations of MS-ARs but enable regime (Markov) switching and detection of structural breaks in the data. These models have long memory, can handle non-linear dynamics, do not require data stationarity or assume error distributions. Thus, they make no assumptions about the data generating process and have the ability to better capture temporal dependencies leading to better forecasting and prediction accuracy over traditional econometric models and plain RNNs. Yet, the partial autocorrelation function and econometric tools, such as the the ADF, Ljung-Box, and AIC test statistics, can be used to determine optimal sequence lag lengths to input into these RNN models and to diagnose serial correlation. The new framework has capacity to characterize the non-linear partial autocorrelation of time series and directly capture dynamic effects such as trends and seasonality. The optimal sequence lag order can greatly influence prediction performance on test data. This structure provides more interpretability to ML models since traditional econometric models are embedded into RNNs. The ability to embed econometric models into RNNs will allow firms to improve prediction accuracy compared to traditional econometric or traditional ML models by creating a hybrid utilizing a well understood traditional econometric model and a ML. In theory the traditional econometric model should focus on the portion of the estimation error that is best managed by a traditional model and the ML should focus the non-linear portion of the model. This combined structure is a step towards explainable AI and lays the framework for econometric AI.
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Title: DATA-DRIVEN OPTIMIZATION OF NEXT GENERATION HIGH-DENSITY WIRELESS NETWORKS
Creator: Khairy, Sami
Date: 2021
Description: The Internet of Things (IoT) paradigm is poised to advance all aspects of modern society by enabling ubiquitous communications and...
Show moreThe Internet of Things (IoT) paradigm is poised to advance all aspects of modern society by enabling ubiquitous communications and computations. In the IoT era, an enormous number of devices will be connected wirelessly to the internet in order to enable advanced data-centric applications. The projected growth in the number of connected wireless devices poses new challenges to the design and optimization of future wireless networks. For a wireless network to support a massive number of devices, advanced physical layer and channel access techniques should be designed, and high-dimensional decision variables should be optimized to manage network resources. However, the increased network scale, complexity, and heterogeneity, render the network unamenable to traditional closed-form mathematical analysis and optimization, which makes future high-density wireless networks seem unmanageable. In this thesis, we study the design and data-driven optimization of future high-density wireless networks operating over the unlicensed band, including Radio Frequency (RF)-powered wireless networks, solar-powered Unmanned Aerial Vehicle (UAV)-based wireless networks, and random Non-Orthogonal Multiple Access (NOMA) wireless networks. For each networking scenario, we first analyze network dynamics and identify performance trade-offs. Next, we design adaptive network controllers in the form of high-dimensional multi-objective optimization problems which exploit the heterogeneity in users' wireless propagation channels and energy harvesting to maximize the network capacity, manage battery energy resources, and achieve good user capacity fairness. To solve the high-dimensional optimization problems and learn the optimal network control policy, we propose novel, cross-layer, scalable, model-based and model-free data-driven network optimization and resource management algorithms that integrate domain-specific analyses with advanced machine learning techniques from deep learning, reinforcement learning, and uncertainty quantification. Furthermore, convergence of the proposed algorithms to the optimal solution is theoretically analyzed using mathematical results from metric spaces, convex optimization, and game theory. Finally, extensive simulations have been conducted to demonstrate the efficacy and superiority of our network optimization and resource management techniques compared with existing methods. Our research contributions provide practical insights for the design and data-driven optimization of next generation high-density wireless networks.
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Title: Towards Assisting Human-Human Conversations
Creator: Nanaware, Tejas Suryakant
Date: 2021
Description: The idea of the research is to understand the open-topic conversations and ways to provide assistance to humans who face difficulties in...
Show moreThe idea of the research is to understand the open-topic conversations and ways to provide assistance to humans who face difficulties in initiating conversations and overcome social anxiety so as to be able to talk and have successful conversations. By providing humans with assistive conversational support, we can augment the conversation that can be carried out. The AdvisorBot can also help to reduce the time taken to type and convey the message if the AdvisorBot is context aware and capable of providing good responses.There has been a significant research for creating conversational chatbots in open-domain conversations that have claimed to have passed the Turing Test and can converse with humans while not seeming like a bot. However, if these chatbots can converse like humans, can they provide actual assistance in human conversations? This research study observes and improves the advanced open-domain conversational chatbots that are put in practice for providing conversational assistance.While performing this thesis research, the chatbots were deployed to provide conversational assistance and a human study was performed to identify and improve the ways to tackle social anxiety by connecting strangers to perform conversations that would be aided by AdvisorBot. Through the questionnaires that the research subjects filled during their participation, and by performing linguistic analysis, the quality of the AdvisorBot can be improved so that humans can achieve better conversational skills and are able to clearly convey their message while conversing. The results were further enhanced by using transfer learning techniques and quickly improve the quality of the AdvisorBot.
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Title: Efficient Power System Transient Simulation for Stability Studies Based on Frequency Response Optimized Approximation
Creator: Lei, Sheng
Date: 2021
Description: Power systems world-wide are going through a paradigm change with dramatically increasing power electronics integration and more emphasis on...
Show morePower systems world-wide are going through a paradigm change with dramatically increasing power electronics integration and more emphasis on the intrinsically unbalanced distribution side. The new features of power systems violate the fundamental assumptions and challenge the feasibility of transient stability simulation, a traditional tool for stability studies. Electromagnetic transient simulation is applicable to power systems with the new features, but its computational efficiency is too low with the typical microsecond-level step sizes.This dissertation aims at enabling millisecond-level step sizes, typically used in traditional transient stability simulation, in efficient electromagnetic transient simulation for system-level stability studies on unbalanced power systems, while assuring satisfactory accuracy. The approach taken is to introduce novel highly accurate numerical methods into electromagnetic transient simulation.Several implicit one-step frequency response optimized integrators considering second order derivative are proposed. Some existing numerical integrators in the literature of this category are reviewed. Their numerical properties are studied. Some of these numerical integrators are especially suitable to be used as numerical differentiators.A novel power system transient simulation scheme is put forward using the implicit one-step frequency response optimized integrators as the main numerical integrators and differentiators. Large step sizes are applicable with the proposed simulation scheme to achieve efficient electromagnetic transient simulation without sacrificing accuracy. Execution of the proposed simulation scheme is detailed.Several explicit and implicit multistep frequency response optimized integrators considering first or second order derivative are proposed. Some existing numerical integrators of these types are reviewed from the error frequency response viewpoint. Based on these numerical integrators, a prediction method is put forward to further accelerate the proposed simulation scheme without impacting its accuracy.Initialization process of the proposed simulation scheme is put forward. The initialization process calculates the periodic steady state solution of unbalanced power systems considering power flow conditions. The requirements of power system stability studies on the initial conditions for transient simulation runs are thus satisfied. Effectiveness and efficiency of the initialization process are demonstrated.Computational models of power system network elements in the proposed simulation scheme are detailed. The extended nodal analysis is put forward for the proposed simulation scheme to organize the computational models of most network elements in an efficient and elegant manner.Some power system devices are implemented with the proposed simulation scheme, including single-phase grid-feeding converter system, three-phase grid-feeding converter system, three-phase synchronous machine and three-phase induction machine. The proposed simulation scheme is shown to simultaneously achieve efficiency and accuracy as applied to these devices.The proposed simulation scheme is applied to different types of power systems, including transmission system, distribution system and combined transmission and distribution system. Its versatility is revealed. Its efficiency and accuracy are demonstrated with numerical case studies as applied to these systems.
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