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Title: Digital Urban Park: Thornton Final
Creator: Thornton, Alastair
Date: 5/4/2011, 2011-05
Description: This project is a park that utilizes social networks and interactivity to convey and make physical the internet. This is explored through...
Show moreThis project is a park that utilizes social networks and interactivity to convey and make physical the internet. This is explored through three parts and varying levels of group interaction between both the users of the space and by the spaces direct influence from the internet.
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Title: Remixed: Reuse, Recycles, Mixed Use, Mixed Income
Creator: Hamburg, Michael
Date: 2012-05-04, 2012-05
Description: A mixed use, mixed income proposal for the Chicago south side, adaptively reusing shipping containers to keep construction costs low

Title: Remixed: Reuse, Recycles, Mixed Use, Mixed Income: REMIXED FINAL BOARD
Creator: Hamburg, Michael
Date: 2012-05-04, 2012-05
Description: A mixed use, mixed income proposal for the Chicago south side, adaptively reusing shipping containers to keep construction costs low

Title: HOW DO SECONDARY STUDENTS MAKE DECISIONS ON SOCIOSCIENTIFIC ISSUES: WHAT DO THEY CONSIDER IMPORTANT?
Creator: LePretre, Dawnne M
Date: 2019
Description: Linking science and action is the epitome of scientific literacy (Hurd, 1972; Kuhn, 1972; Watson, 1969). Before becoming acting citizens,...
Show moreLinking science and action is the epitome of scientific literacy (Hurd, 1972; Kuhn, 1972; Watson, 1969). Before becoming acting citizens, students need to balance subject matter knowledge, personal values, and societal norms in decision-making (DM) on Socioscientific Issues (SSI) (Aikenhead, 1985; Grace & Ratcliffe, 2002; Kolstø, 2001; Zeidler, 1984). Existing literature suggests a variety of models and strategies to guide how students should think about SSI topics versus beginning with what students are thinking concerning SSI! This study aimed to identify the DM factors students considered across a variety of SSI and to determine if DM factors were common across topics or specific to a SSI. Students in grades 10-12 participated from seven schools and ten regular science classrooms, primarily located in a large Midwest city (n=498). The sample was 50% female, 50% male, and roughly 33% of students from each grade level.Across 60 enacted lessons on six different SSI topics, multiple sources of data were collected, including student artifacts, audiotapes of class discussions/interviews, field notes, and teacher surveys. Students engaged in a minimum of three different SSI topical lessons, implemented over a period between one to nine weeks for an average instructional time of 115 minutes per topic. Decision-making differed across students in various groupings, indicating that secondary students used both general and specific factors when making decisions on SSI. Further, trends emerged, indicating various student groups' valued DM factors differently. On several topics, students of different gender, grade levels, ethnicities, and school type considered different DM factors to different levels of support. For example, on the topic of plastics and pollution, 10th grade, female, and Hispanic students tended to identify concern for animals and sea life as their most prominent DM factor. Another trend included larger class sizes tending to cite more DM factors on a topic than students in smaller sized classrooms engaged on the same topic. Overall, 15 common or shared DM factors emerged that students considered when making decisions across multiple SSI contexts. In addition, each specific SSI context had between one and 15 specific or exclusive DM factors cited directly by students in this study.
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Title: Rapidly Deployable PV-Based Smart Irrigation System
Creator: Usta, Salih
Date: 2019
Description: There are many agricultural fields in developing countries such as Turkey which do not have electricity on site. In order to water these...
Show moreThere are many agricultural fields in developing countries such as Turkey which do not have electricity on site. In order to water these fields, there is usually a need to store water in a water reservoir nearby. This purpose is achieved by manpower or by using diesel-operated water pumps which are often inefficient and require a high degree of maintenance over time. Furthermore, extending the power supply grid to the field is not considered an option by governors, due to the high cost for a relatively small-scale application. Along with this, watering the field is done by farmers, which frequently leads to waste of water, or leads to watering one particular area of the field less than the others, which causes a drop in crop efficiency. Preventing water waste is considered an important issue in the 21st century. Also, increasing crop efficiency in a developing country is an important consideration. To prevent water waste and to enhance crop efficiency, an automated irrigation system is needed. The objective of this study is to develop a photovoltaic-based irrigation system for an agricultural field that is not tied to an existing conventional electric grid. Firstly, a stand-alone PV system is designed according to the field requirements. Secondly, a soil moisture sensor-based smart irrigation system is developed for an automated irrigation process compatible with drip irrigation systems. This system also enables users to monitor and analyze soil moisture data. By developing this type of complete irrigation mechanism, a long-term lower cost, efficient, and environmental-friendly system is designed.
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Title: Development of a Job Attitudes Composite for Measuring Employee Engagement
Creator: Vallejo, Rodney Scott
Date: 2019
Description: The measurement of employee engagement is important for researchers and practitioners given its relation to positive work outcomes and...
Show moreThe measurement of employee engagement is important for researchers and practitioners given its relation to positive work outcomes and importance to company success. Although numerous measures of employee engagement have been established, they lack depth and fall short in potentially explaining why an employee may or may not be engaged in the workplace. The current study aimed to provide an alternative way of measuring employee engagement at a finer level by utilizing job attitudes and a composite approach. Specifically, job attitudes from an employee survey instrument that were identified as antecedents to employee engagement were organized into a composite and relationships with employee engagement and employee turnover were tested. Results showed a both relationship between a composite of job attitudes and employee engagement and utility of the composite by predicting employee turnover.
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Title: Measuring Maternal-Fetal Attachment: Model Fit and Measurement Invariance of a New Assessment Tool
Creator: Hedrick, Laura
Date: 2019
Description: The importance of studying Maternal-Fetal Attachment (MFA) as part of the system of maternal-child perinatal functioning is well established...
Show moreThe importance of studying Maternal-Fetal Attachment (MFA) as part of the system of maternal-child perinatal functioning is well established in the literature, as MFA relates to health-related and psychosocial variables both during pregnancy and after the infant is born (e.g., positive health behaviors in pregnancy; levels of maternal stress, anxiety, and depressive symptoms; positive parenting behaviors after the child is born; and secure infant attachment at age one year). Despite the apparent value of studying MFA, there is no acceptable measurement tool for the construct. Existing assessment tools often do not meet minimum psychometric standards, may not be practical for broad research application, and have demonstrated inconsistent results in correlational research. Therefore, a clear need exists for a measurement scale with strong psychometric properties that is based on empirically supported development strategies. The present line of research sought to fill this need. The process of developing a new measurement tool began in a previous study, Hedrick (2015), which used Exploratory Factor Analyses to identify options for a potential measurement scale from subsets of a large pool of items intended to measure MFA. In Hedrick (2015), three options were identified as acceptable, then compared based on ranges of communalities, percentage of variance explained, internal consistency, and performance on two measures of concurrent and discriminant validity. However, these assessments failed to differentiate a single option as most preferable. Therefore, the first aim of present study was to complete the task of differentiating among the working measures to choose a measurement scale. Confirmatory Factor Analysis (CFA) was used to attempt to determine which working measure from the EFA study had the factor structure that fit best in a second sample of participants. The CFA process was not able to differentiate a superior working measure from the options. Therefore, the most theoretically sound of the three was chosen to use as a measurement tool, with some small adjustments made based on the CFA results. To continue to establish the validity of the new questionnaire measure, the second aim of the study was to assess its measurement invariance among different administration methods and populations. The measurement tool was found to be non-invariant in both areas. Specifically, the results of the measurement invariance analyses indicated that the measure should be administered on paper rather than online, would be best applied in research in African American/Black populations than in research with other racial/ethnic groups, and should not be used to compare MFA scores among racial/ethnic groups. Measurement invariance analyses also revealed that the scale was non-invariant at the metric level regarding parity groups. The implications of these findings for further research is discussed.
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Title: STAKEHOLDER FEEDBACK ON A NOVEL EMOTION REGULATION INTERVENTION FOR PRESCHOOL-AGE CHILDREN WITH DISRUPTIVE BEHAVIOR PROBLEMS: A THEMATIC ANALYSIS
Creator: Lossia, Amanda
Date: 2019
Description: Disruptive behavior disorders are among the most prevalent psychological disorders in preschoolers. There are evidence-based treatments for...
Show moreDisruptive behavior disorders are among the most prevalent psychological disorders in preschoolers. There are evidence-based treatments for these disorders, but clinically significant behavior problems persist in approximately one-fourth to one-third of children after treatment. These treatments consist of behavioral parenting interventions and are not designed to directly address children’s affective dysregulation, which is a core component of behavior problems. To address this limitation, a manualized intervention was developed to treat disruptive behavior in preschool-age children by specifically targeting their emotion regulation abilities as the mechanism of change by coaching the caregiver to scaffold the child’s emotion regulation strategy use. The purpose of the present study was to further the development of this intervention by obtaining feedback from key stakeholders (i.e., caregivers and therapists) on the intervention’s focus, content, and procedures. Obtaining this feedback is an essential component of developing a novel psychosocial intervention. A qualitative thematic analysis of in-depth focus group discussions was conducted. Data were organized into the following broad themes: Intervention approach (support for targeting emotion regulation but ensuring the approach is an appropriate fit and considering the important role of behavioral strategies; additional focus on facilitating a positive caregiver-child relationship; developing some independent regulation skills in the child), Intervention structure and session content (making the intervention structure more flexible or modular; retaining the main intervention components with modifications to enhance acceptability, relevance, and developmental appropriateness), The caregiver’s role (the caregiver’s role is of primary importance and should be active throughout all sessions; ensuring adequate caregiver preparation and skill development; additional primary focus on facilitating the caregiver’s own emotion regulation; attention to the caregiver’s own therapeutic needs), Individualized approach (individualizing the content and timing of all sessions to account for individual needs), Generalizability (ensuring generalization of skills to home and other settings through effective at-home practice and including other primary caregivers and family members in sessions), and Learning and skill development (considering individual differences in how children and caregivers learn and modifying activities accordingly). These themes and stakeholders’ specific feedback will guide revisions to the intervention manual prior to pilot testing and further examination of efficacy and effectiveness.
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Title: Energy Scale Study for PROSPECT's Measurement of the Antineutrino Spectrum of 235U
Creator: Zhang, Xianyi
Date: 2019
Description: Neutrinos from nuclear fission reactors have been widely studied in particle and nuclear physics. In the last ten years, the antineutrino flux...
Show moreNeutrinos from nuclear fission reactors have been widely studied in particle and nuclear physics. In the last ten years, the antineutrino flux and spectrum were measured independently by short baseline reactor experiments. Both flux and spectrum measurements showed discrepancies compared to theoretical models based on historical measurements and nuclear databases. These discrepancies hint at sterile neutrino oscillation at the eV mass scale, as well as an incomplete theoretical model. PROSPECT, the Precision Reactor Oscillation and Spectrum experiment, was built to probe for sterile neutrino oscillations and precisely measure the reactor antineutrino spectrum from a highly 235U enriched reactor. The PROSPECT antineutrino detector is an optically segmented liquid scintillator detector deployed at seven meters to nine meters from the High Flux Isotope Reactor at Oak Ridge National Laboratory. This dissertation details the analysis to calibrate the energy scale of the PROSPECT antineutrino detector, an essential step for both the oscillation and spectrum measurements. To characterize the nonlinear detector energy response, a unique calibration and analysis strategy was developed to overcome challenges brought on by particle multi-segment scattering within the PROSPECT detector. With the calibrated scale for energy reconstruction, PROSPECT measured of the antineutrino spectrum from a 235U-burning reactor.
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Title: EVALUATION OF LISTERIA MONOCYTOGENES ENRICHMENT AND COMPOSITING PROTOCOLS FROM ENVIRONMENTAL SAMPLES
Creator: Eckert, Christine
Date: 2019
Description: Environmental sampling in a food production plant is routinely conducted using devices, such as sponges or swabs, to verify cleaning...
Show moreEnvironmental sampling in a food production plant is routinely conducted using devices, such as sponges or swabs, to verify cleaning procedures and determine if any foodborne pathogens, such as Listeria monocytogenes (L. monocytogenes), are present. The devices used for environmental monitoring are enriched to improve pathogen detection. This study aims to 1) compare the limit of detection (LOD) of L. monocytogenes of two U.S. Food and Drug Administration (FDA) enrichment procedures (i.e., Bacteriological Analytical Manual (BAM) and Compliance Document) with and without food matrix, and to 2) assess the number of samples which can be wet and dry composited without loss of sensitivity from stainless steel. To compare the LOD of L. monocytogenes using UVM and BLEB, three inoculation levels (0.27±0.07, 0.59±0.05, and 1.00±0.15 CFU per 225 mL enrichment) with 30 enrichments each were used. Results showed that there was no significant difference between the number of samples where L. monocytogenes was detected for UVM and BLEB at any of the three inoculation levels. However, the limit of detection (LOD95%) for UVM/Fraser was higher than that of BLEB (2.13 and 1.44 CFU/mL, respectively). For wet compositing, 1.24±0.34 CFU of L. monocytogenes was inoculated into 45 enrichments of UVM or BLEB without food matrix and 7.2±0.18 CFU of L. monocytogenes was inoculated into 30 enrichments of UVM or BLEB with 4.13±0.12 log CFU of native microflora from Romaine lettuce wash (RLW). Secondary composite enrichments in Fraser broth were conducted at each of four different ratios: 1:1 (1 positive:1 negative), 1:2 (1 positive: 2 negative), 1:4 (1 positive: 4 negative), and 1:7 (1 positive:7 negative). There was no significant difference between the number of samples where L. monocytogenes was detected between BLEB and UVM with or without food matrix at any of the composite ratios. When comparing wet and dry compositing enrichments from stainless steel, 10.16 × 10.16 cm areas on stainless steel plates were inoculated with 464±22 CFU (2.67±0.24 log CFU) L. monocytogenes, dried for 24 h, and sponges were used to swab the surface of the plates. The sponges were then composited (into primary enrichments for dry compositing) or the secondary enrichments were composited (for wet compositing). Compositing was conducted with RLW containing 4.13±0.02 log CFU of background microflora. There was no significant difference between the number of samples where L. monocytogenes was detected for BLEB and UVM when comparing dry or wet compositing at any of the composite ratios tested. Results of this thesis will aid in determining if compositing of environmental samples is an option when L. monocytogenes is the target pathogen.
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Title: A SCALABLE SIMULATION AND MODELING FRAMEWORK FOR EVALUATION OF SOFTWARE-DEFINED NETWORKING DESIGN AND SECURITY APPLICATIONS
Creator: Yan, Jiaqi
Date: 2019
Description: The world today is densely connected by many large-scale computer networks, supporting military applications, social communications, power...
Show moreThe world today is densely connected by many large-scale computer networks, supporting military applications, social communications, power grid facilities, cloud services, and other critical infrastructures. However, a gap has grown between the complexity of the system and the increasing need for security and resilience. We believe this gap is now reaching a tipping point, resulting in a dramatic change in the way that networks and applications are architected, developed, monitored, and protected. This trend calls for a scalable and high-fidelity network testing and evaluation platform to facilitate the transformation from in-house research ideas to real-world working solutions. With this objective, we investigate means to build a scalable and high-fidelity network testbed using container-based emulation and parallel simulation; our study focuses on the emerging software-defined networking (SDN) technology. Existing evaluation platforms facilitate the adoption of the SDN architecture and applications to production systems. However, the performance of those platforms is highly dependent on the underlying physical hardware resources. Insufficient resources would lead to undesired results, such as low experimental fidelity or slow execution speed, especially with large-scale network settings. To improve the testbed fidelity, we first develop a lightweight virtual time system for Linux container and integrate the system into a widely-used SDN emulator. A key issue with an ordinary container-based emulator is that it uses the system clock across all the containers even if a container is not being scheduled to run, which leads to the issue of both performance and temporal fidelity, especially with high workloads. We investigate virtual time approaches by precisely scaling the time of interactions between containers and physical devices. Our evaluation results indicate a definite improvement in fidelity and scalability. To improve the testbed scalability, we investigate how the centralized paradigm of SDN can be utilized to reduce the simulation workload. We explore a model abstraction technique that effectively transforms the SDN network devices to one virtualized switch model. While significantly reducing the model execution time and enabling the real-time simulation capability, our abstracted model also preserves the end-to-end forwarding behavior of the original network.With enhanced fidelity and scalability, it is realistic to utilize our network testbed to perform a security evaluation of various SDN applications. We notice that the communication network generates and processes a huge amount of data. The logically-centralized SDN control plane, on the one hand, has to process both critical control traffic and potentially big data traffic, and on the other hand, enables many efficient security solutions, such as intrusion detection, mitigation, and prevention. Recently, deep neural networks achieve state-of-the-art results across a range of hard problem spaces. We study how to utilize the big data and deep learning to secure communication networks and host entities. For classifying malicious network traffic, we have performed the feasibility study of off-line deep-learning based intrusion detection by constructing the detection engine with multiple advanced deep learning models. For malware classification on individual hosts, another necessity to secure computer systems, existing machine learning-based malware classification methods rely on handcrafted features extracted from raw binary files or disassembled code. The diversity of such features created has made it hard to build generic malware classification systems that work effectively across different operational environments. To strike a balance between generality and performance, we explore new graph convolutional neural network techniques to effectively yet efficiently classify malware programs represented as their control flow graphs.
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Title: Wind Turbine Building
Creator: Tseng, Ling Yi
Date: 5/4/2011, 2011-05
Description: Wind Turbine Building with Venturi Tube
Sponsorship: Land, Peter

Title: Reconditioning Dharavi: A Toolkit of Strategies for Incremental Development
Creator: Bhogle, Saylee Deepak
Date: 2022
Description: The 2003 Global Report on Human Settlements (Un-Habitat, 2003) defines a "slum" as a densely populated metropolitan area that is distinguished...
Show moreThe 2003 Global Report on Human Settlements (Un-Habitat, 2003) defines a "slum" as a densely populated metropolitan area that is distinguished by a variety of low-income settlements, subpar housing, and squalor. Dharavi, on the other hand, is far more than a "slum." In the heart of Mumbai, Dharavi is an economically prosperous and socially active informal town. Mumbai is a thriving metropolis with many different realities and patterns, even though it appears to be a slum filled with squatters. However, the region has recently become a hub for informal settlements and urban problems associated with poor hygiene in developing countries. People’s misconceptions about Dharavi stem from a failure to recognize its social capital and economic power: the area encompasses a variety of economic networks, production types, income levels, land tenure arrangements, and religious activities and festivities. Dharavi is made up of 85 separate groups with a strong feeling of belonging and high expectations for stability and improved economic position and living standards. It is also clear that these folks are capable of building and enhancing their shelter if they have the resources to do so. To develop all these qualities, Dharavi's Social Capital must be recognized and promoted as an asset to the city of Mumbai. A community such as Dharavi requires ‘urban acupuncture’; where mediation of the littlest kind will have the greatest effect. Dharavi, like any other "Informal" city, requires rigorous examination to be fully comprehended. It is a unique location where a large flood of migrants has managed to build jobs and their city. My underlying attitude to this location is a conflicting desire to save and replace it. The desire to save is linked to the aesthetic of informality as well as the intense sociality, diversity, and production of the streets and lanes - a fascinating and diversified urban ensemble. The desire to eliminate stems from hopeless states of sterilization, ventilation, light, open space, and congested areas. As a result, a reliable strategy for combining the two methodologies and locating a functioning arrangement should be developed. The government has been trying to redevelop this area for the past 50 years but hasn’t been successful in doing so. In contrast to the existing redevelopment plan, which promotes uniform top-down development, my concept anticipates techniques for progressive self-development, including "bottom-up" finance models and architectural approaches. After identifying various patterns and carefully examining behavior patterns, production systems, and existing community facilities, a toolkit of methods can be built that can be used in various places and "outboxes." The simple homogeneity of solutions for Dharavi's changing conditions has been avoided. Dharavi's current identity and "mixed-use" paradigm have been respected, with Home recognized as an instrument of production. The proposed design has been tested for various environmental factors using different tools for natural lighting and ventilation. The outdoor areas are also analyzed for thermal comfort since a lot of social activities take place in these areas. Communal areas have been designed to accommodate micro infrastructure systems while also increasing productivity. As a result, a system of self-development triggers has been created that can improve present conditions while also supporting the community's need for stability. Simultaneously, by focusing on property ownership as an economic driver, the proposed approach can provide a type of "social mobility" for Dharavi's residents.
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Title: RE-DEFINING LABOR HOUSING COMMUNITIES IN DUBAI
Creator: Chavadi, Sanjana Mrutyunjaya
Date: 2022
Description: From the moment they are duped into believing in a utopian lifestyle, to their day to-day working and living conditions once they arrive in...
Show moreFrom the moment they are duped into believing in a utopian lifestyle, to their day to-day working and living conditions once they arrive in the country, to the denial of theirrights for years after they are stuck in the country, the migration of workers from other countries into the Emirates is a neglected humanitarian issue. The United Arab Emirates and several other GCC countries have a heinous habit of recruiting illiterate foreigners into their country and abusing them as if they were modern-day slaves. Many nations and individuals have legal control over immigrants by applying the Kafala sponsorship system and ignoring international norms and rights established by organizations like the International Labor Organization. While the Kafala system is only one of many aspects of the whole problem, this thesis will seek to identify the influence of architecture on the lives of the South Asian labor force who work behind the beautiful façade of the United Arab Emirates by reconstructing the labor community. These colossal structures are built and shown while the individuals who construct them are ignored and hidden. Immigrant low income labor employees bear the brunt of their hard life-work imbalance with the intention of providing assistance to their family in their home nations. The labor force of Dubai becomes the major target of the terrorists, isolated from Dubai's pleasure amenities, socially detached from the rest of the population, and separated from their creations. By creating a landmark and developing a sense of social coherence, integration, and empowerment among the labor community, this initiative intends to bridge the divide and commemorate the labor community. This project will propose a new sort of community and housing typology that embraces the ideals of modularity, adaptability, and community as a solution to the immigrant worker dilemma.
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Title: Habitat 2022+
Creator: Cho, San Lae Lae
Date: 2021
Description: Globalization and urbanization have led a vast group of population to shift from rural and suburban areas to urban centers. According to the...
Show moreGlobalization and urbanization have led a vast group of population to shift from rural and suburban areas to urban centers. According to the United Nation’s (UN) projection, around 2.5 billion more people will live in the cities by 2050. For cities to accommodate such a population, cities can grow horizontally or vertically. If cities were to grow horizontally, this population would need to commute majorly by car which has a very high carbon footprint. By building vertically, the population’s commute becomes more efficient if the vertical structure is built as such is a city within a city. Although having existed for 500 years, tall buildings and skyscrapers have been topics of controversy for their excessive use of resources, ignoring environmental and contextual problems. In order to mitigate this sustainability issue, mass timber as a construction material has been recently introduced into the American market. Mass timber is the building material for a carbon neutral future according to Council on Tall Buildings and Urban Habitats (CTBUH). Another means is to grow plants around the buildings meaning they are regrowing greenery back into nature with the hopes to take a step towards mitigating climate change. In addition, with the argument of tall buildings lacking neighborhood-like qualities that for instance, a Chicago block of housing may give, more and more tall buildings around the world have tried to implement the lush spaces onto the building perimeters. These spaces with plants and trees mimicking nature can exist as both indoor and outdoor spaces. While neighborhoods have parks, these spaces or sky gardens will substitute as modified parks for skyscrapers.With psychological benefits tied to spaces linked to nature in high-rises, such spaces should be integrated in all high rise, residential buildings. Today, in addition to Covid pandemic, many people practice working from home. Meanwhile, it is human nature since birth to want to be surrounded by plants and nature, either spending time under a tree or lying on the grass. To mitigate spending excessive amounts of hours indoors, spaces linked to nature have become crucial in providing a sense of peace and reconnecting back to nature. However, currently architecture that has nature integrated, results in spaces only for the wealthy. Furthermore, architecture in the US is so commercially driven with developers aiming for the most cost effective, most efficient and largest floor areas. For nature to be more available to the living spaces of middle class and ideally working class, the city planners and city development authorities need to get involved. For instance, the city could aid by allocating some of the tax collected to build more green architecture. With the tax fund assistance from the city, high quality living of green architecture will become available and much more affordable.Another option to making living more affordable is by implementing co-living. Despite the Covid-19 pandemic, co-living remains relatively high in demand in Chicago according to Chicago Tribune. For the younger generations such as the Millennials and younger, it is predicted that due to the nature of student loan debts, these generations are less likely to be financially well off after graduation. Hence, they are less likely to establish a family as soon as the previous generations, as most people tend to start a family when they feel financially stable.Hence, in this design thesis, a certain prototype will be tested out regarding some of these issues. This is just one option to the issues above and there are many options and other nuances still available to explore.
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Title: High-integrity modeling of non-stationary Kalman Filter input error processes and application to aircraft navigation
Creator: Gallon, Elisa
Date: 2023
Description: Most navigation applications nowadays rely heavily on Global Navigation Satellite Systems (GNSSs) and inertial sensors. Both of these systems...
Show moreMost navigation applications nowadays rely heavily on Global Navigation Satellite Systems (GNSSs) and inertial sensors. Both of these systems are known to be complementary, and as such, their outputs are very often combined in an extended Kalman Filter (KF) to provide a continuous navigation solution, resistant to poor satellite geometry, as well as radio frequency interference. Additionally, recent development in safety critical applications (such as aviation) revealed the performance limitations of current algorithms (Advance Receiver Autonomous Integrity Monitoring - ARAIM) to vertical guidance down to 200 feet above the runway (LPV-200). When nominal constellations are depleted, LPV-200 can only sparsely be achieved. Exploiting satellite motion in ARAIM (for instance using a KF) could help alleviate those limitations, but would require adequate modeling of the errors, including the error's time correlation.Power Spectral Density (PSD) bounding is a methodology that provides high integrity, time correlated error models, but this approach is currently limited to stationary errors (which is rarely the case with real data), and has never been applied to navigation errors. More generally, no high integrity, time correlated error models have ever been derived for navigation errors.As a result, in the first part of this thesis, a methodology for high integrity modeling of time correlated errors is introduced. The PSD bounding methodology is extended to both stationary and non-stationary errors. In the second part of this thesis, these methodologies are applied to the 3 main error sources impacting iono-free GNSS measurements (orbit and clock errors, tropospheric errors and multipath), as well as to inertial errors.The methodology introduced in this dissertation provides high integrity time correlated error models and is applicable to any type of applications where high integrity is required (e.g. Differential GNSS - DGNSS, Aircaft Based Augmentation System - ABAS, Ground Based Augmentation System - GBAS, Space Based Augmentation System - SBAS, etc...). Additionally, the error models derived here are not only limited to high integrity applications, but could also be used in applications were the correlation over time of the errors plays an important role (such as any KF integration).In the last part of this dissertation, we focus on a specific safety critical application: aviation, and in particular ARAIM. The dissertation is concluded with an assessment of the performance improvements provided by recursive ARAIM, using those bounding dynamic error models, with respect to those models, used for baseline snapshot ARAIM. Additionally, a sensitivity analysis is performed on each of the error model parameters to assess which of them impacts the KF performance (i.e. covariance) the most.
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Title: Effect of heat treatment on microstructure and electrochemical behavior of laser powder bed fusion hydride- dehydride ti-6al-4v alloy
Creator: Delpazir, Melody Honardan
Date: 2022
Description: In powder bed additive manufacturing, feedstock and processing have an impact onfinal microstructure and properties of 3D-printed parts. While...
Show moreIn powder bed additive manufacturing, feedstock and processing have an impact onfinal microstructure and properties of 3D-printed parts. While numerous studies have evaluated 3D-printing of spherical powder, very limited research has been carried out on the processing of the non-spherical feedstock. This study is targeted specifically to the use of non-spherical Ti-6Al-4V powders in the laser powder bed fusion (L-PBF) process. Two different post-heat-treatments including hot isostatic pressing and solution treatment are applied. The microstructure evaluation, potentiodynamic polarization, and electrochemical impedance spectroscopy methods are used to characterize L-PBF processed and post- treated specimens. Though as-built part exhibits anisotropic microstructure containing acicular α′ martensite with trace amount of β phase, the heat-treated parts are composed of α+β in which length and thickness of the α-lath depends on the treatment. The below β transus heat treatment leads to the formation of a homogenized grain structures composed of α+β. Electrochemical results show that the below β transus heat-treatment had a slight positive effect on the improvement of corrosion resistivity (corrosion rate of 4.2×10-6 mmy- 1 , which is classified as an excellent ) compared to other conditions, which would be associated to the natural excellent corrosion resistance of Ti-6Al-4V alloy. This slight improvement can be ascribed by the slightly faster formation of a passive layer and its enhanced efficiency because of the presence of the fine-structured β phase in post heat- treated L-PBF processed Ti-6Al-4V alloy.
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Title: Fatigue Life Prediction for Structures with Interval Uncertainty
Creator: Desch, Michael R.
Date: 2022
Description: A new method for reliable fatigue life prediction in metal structural components is developed where uncertainties are quantified using...
Show moreA new method for reliable fatigue life prediction in metal structural components is developed where uncertainties are quantified using interval variables. Using this crack-initiation-based method, first, the uncertainties in laboratory test data for the fatigue failure of a structural detail are enumerated. This uncertainty quantification is performed through an interval-based enveloping procedure that relates the interval stress ranges to the number of cycles to failure, leading to the construction of an interval S-N relationship. Next, the uncertainties in field test data are enumerated in the extremum values of each stress range, as intervals, leading to the construction of interval stress ranges. For both the laboratory and field data uncertainty analyses, the mean stress effects are considered. Next, the interval damage accumulated over the duration of the field data is determined using the constructed interval S-N relationship and the obtained interval stress ranges. Then, the interval existing damage and interval remaining life are determined. Finally, as a conservative measure, the minimum remaining fatigue life is obtained in which all uncertainties are considered. Three numerical examples illustrating the developed method are presented, and the results are compared with results obtained by both Monte Carlo simulation and optimization. Using this method, for the numerical examples considered, it is shown that the results for bounds on the existing damage and the remaining fatigue life are sharp. Moreover, due to its set-based approach, the method is significantly more computationally efficient when compared with iterative procedures.
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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: SEPARATING NOBLE GASES SUCH AS KRYPTON AND XENON FROM NUCLEAR POWER PLANTS OFF-GAS USING DD3R ZEOLITIC MEMBRANES: A COMPUTATIONAL MOLECULAR DYNAMICS STUDY
Creator: BASHMMAKH, BANDAR JAMAL S.
Date: 2021
Description: Noble gas fission products generated within nuclear power reactors, such as Kr and Xe, are currently discharged into the atmosphere. This...
Show moreNoble gas fission products generated within nuclear power reactors, such as Kr and Xe, are currently discharged into the atmosphere. This practice has a major economic drawback because of the high value associated with some of these gases. Zeolites, nanoporous materials suitable for gas separation processes, have become of major interest due to the potentially high selectivity for such separations. We have used nonequilibrium molecular dynamics to investigate the separation performance of DD3R framework zeolitic membranes (using LAMMPS software package) for such separations. Our studies have shown that the DD3R membrane shows promise for high selectivity ratios of Kr over Xe. The effects of pressure, temperature and pure vs. mixture gas feed conditions are studied in this work to understand at the molecular level the mechanisms of these (Kr/Xe) separations. MD runs show an agreement with most experimental trends in the permeation of Kr/Xe pure and mixed gases using DD3R zeolite with high separation factor, despite the absence of Xe complete permeation through the membrane because of MD timescale limitation, signaling much slower diffusion in comparison to Kr which is a desired trend in looking for high separation factors.
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