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Title: Two sides on "normal" : a comparison of eight views on U.S. rapprochement with Vietnam, 1989-1995
Creator: Clason, Nathan Robert
Date: 2017
Collection: Electronic Theses & Dissertations
Description: ABSTRACTTWO SIDES ON "NORMAL:" A COMPARISON OF EIGHT VIEWS ON U.S. RAPPROCHEMENT WITH VIETNAM, 1989-1995ByNathan Robert Clason This thesis is a comparative study of the views of eight entities regarding the prospect of normalization of diplomatic relations between the United States and the Socialist Republic of Vietnam from 1989-1995. It first describes the views and actions of five entities in favor of normalization. These include the four US presidential administrations from Carter to...
Show moreABSTRACTTWO SIDES ON "NORMAL:" A COMPARISON OF EIGHT VIEWS ON U.S. RAPPROCHEMENT WITH VIETNAM, 1989-1995ByNathan Robert Clason This thesis is a comparative study of the views of eight entities regarding the prospect of normalization of diplomatic relations between the United States and the Socialist Republic of Vietnam from 1989-1995. It first describes the views and actions of five entities in favor of normalization. These include the four US presidential administrations from Carter to Clinton, the Vietnamese Communist Party, the Senate Select Committee on POW/MIA Affairs (1991-1993), US Senators John McCain and John Kerry, and US businesses. It then examines the views and actions of three entities opposed to normalization. These include Ann Mills Griffiths, the Executive Director of the National League of POW/MIA Families; Texas billionaire Ross Perot; and politicians such as Robert Dornan and Vietnamese Americans from Orange County, California. By using a comparative approach, this thesis identifies several strange political alliances and enmities that would not have been clear in a more linear history. It includes a review of Vietnamese Communist Party documents that challenges some of the conclusions of the earliest diplomatic histories about normalization. It uses primary sources from key Senate Hearings to challenge elements of cultural histories about the myth of live US prisoners of war abandoned in Southeast Asia, and it personalizes the views of Ann Mills Griffiths and some Vietnamese Americans to give better context to their ardent opposition to normalization.
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Title: Two beginning teachers' intervention in small groups in figured worlds of mathematics classrooms
Creator: Pak, Byungeun
Date: 2020
Collection: Electronic Theses & Dissertations
Description: The purpose of this dissertation study is to understand beginning teachers' intervention in small groups. In this qualitative study, drawing on the notion of figured worlds (Holland, Lachicotte, Skinner, & Cain, 1998), I examined how beginning elementary teachers intervene in small groups and for what purposes in mathematics classrooms through the lenses of teacher noticing, teacher identity, and perceptions of students in mathematics classrooms. Working with two beginning teachers, I...
Show moreThe purpose of this dissertation study is to understand beginning teachers' intervention in small groups. In this qualitative study, drawing on the notion of figured worlds (Holland, Lachicotte, Skinner, & Cain, 1998), I examined how beginning elementary teachers intervene in small groups and for what purposes in mathematics classrooms through the lenses of teacher noticing, teacher identity, and perceptions of students in mathematics classrooms. Working with two beginning teachers, I collected data including survey responses, video-recordings, and interview transcripts.Building on thematic analysis of these data, I present three findings in relation to in terms of teacher noticing, teacher identity, and perceptions of students. First, I offer a noticing-mediated intervention framework that contributes to understanding how beginning teachers may make decisions related to intervention in small groups. This framework provides several ways to (re-)construct individual teachers' decision-making process related to intervention. Second, I demonstrate how current and designated teacher identities shape their intervention in small groups. I detail multifaceted aspects of current and designated teacher identity that each beginning teacher invoked to explain, make sense of, and reason about their intervention in small groups. Third, I illustrate how teachers' recognition of students in terms of categories shapes their intervention in small groups, sometimes through mediation by their recognition of power and authority dynamics at the micro-interaction level.Building on these findings, I present four points to discuss. First, this dissertation study can serve as a call for research on extending the understanding of novice teachers' intervention in diverse contexts. Second, this study suggests one possible example related to how to draw upon professional noticing to examine intervention in small groups in a detailed way. Third, this study details potential resources (e.g., knowledge, expectations, and experiences; teacher identity; and categories of students) beginning teachers may use when they make decisions to intervene in small groups. Fourth, this study supports the field to understand figured worlds of mathematics classrooms from beginning teachers' perspectives of intervention in small groups.This dissertation study has implications for research as well as for teacher education. For research, this study contributes to understanding how teacher noticing can be used to explore teachers' intervention in small groups. It also holds promise for ways to understand mathematics classrooms as figured worlds. For teacher education, teacher educators can use this study to design instructional activities that help novice teachers explore their intervention in small groups in relation to the noticing-mediated intervention framework, the multiple aspects of their current/designated identities, and their recognition of students in terms of different categories in mathematics classrooms. This study broadens and deepens the understanding of how beginning teachers intervene in small groups and for what purpose by relating it to teacher noticing, to teacher identity, and to figured worlds of mathematics classrooms.
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Title: Two Studies in Nonlinear Biological System Modeling and Identification
Creator: Yan, Jinyao
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Biological systems are often complex, nonlinear and time-varying. The modeling of biological systems, therefore, presents significant challenges that are not overcome by the classical linear methods. In recent decades, intensive research has begun to produce methods for analyzing and modeling isolated classes of nonlinear systems. However, this vast class of models still presents many challenges, especially in complex biological systems. In this research, two novel methods are introduced for...
Show moreBiological systems are often complex, nonlinear and time-varying. The modeling of biological systems, therefore, presents significant challenges that are not overcome by the classical linear methods. In recent decades, intensive research has begun to produce methods for analyzing and modeling isolated classes of nonlinear systems. However, this vast class of models still presents many challenges, especially in complex biological systems. In this research, two novel methods are introduced for analyzing time series resulting from nonlinear systems. In the first approach, we study a class of dynamical systems that are nonlinear, discrete and with a latent state-space. We solve the probabilistic inference problem in these latent models using a variational autoencoder (VAE). Compared to continuous latent random variables, the inference of discrete latent variables is more difficult to solve. However, stochastic variational inference provides us with a general framework that tackles the inference problem for this class of model. We focused on an important neuroscience application – inferring pre- and post-synaptic activities from dendritic calcium imaging data. For it, we developed families of generative models, a deep convolutional neural network recognition model, and methods of inference using stochastic gradient ascent VAE. We benchmarked our model with both synthetic data, which resembles real data, and real experimental data. The framework can flexibly support rapid model prototyping. Both the generative model and recognition model can be changed without perturbing the inference. This is especially beneficial for testing different biological hypotheses. As a second approach, we treat a subclass of nonlinear autoregressive models: linear-time-invariant-in-parameters models. This class of models is useful and easy to work with. We propose an identification algorithm that simultaneously selects the model and does parameter estimation. The algorithm integrates two strategies: set-based parameter identification, and evolutionary algorithms that optimize fitness measures derived from these solutions. The algorithm can identify nonlinear models in novel noise scenarios. We show the performance of the algorithm in various simulated systems and practical datasets. We demonstrate its application to identify causal connectivity in a graph. This problem is often posed in recovering functional connectivity in the brain. The main contribution of this thesis is that we provide two framework for identifying nonlinear, biological systems from time series data. These two classes of nonlinear models and their applications are significant as each class is broad enough for modeling many complicated biological systems. We develop general, fast algorithms for learning these systems from data for these two model classes.
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Title: Transparent multijunction organic photovoltaics
Creator: Young, Margaret (Process engineer)
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "The widespread adoption of conventional solar cells based on inorganic semiconductors has been gaining traction in recent years but is still often hindered by high cost and lack of aesthetic appeal. Transparent organic semiconductor-based solar cells that selectively absorb in the UV and the NIR enable integration into building windows, automobiles, and consumer electronics in ways that traditional solar cells cannot. Moreover, integration onto existing infrastructure reduces the racking and...
Show more"The widespread adoption of conventional solar cells based on inorganic semiconductors has been gaining traction in recent years but is still often hindered by high cost and lack of aesthetic appeal. Transparent organic semiconductor-based solar cells that selectively absorb in the UV and the NIR enable integration into building windows, automobiles, and consumer electronics in ways that traditional solar cells cannot. Moreover, integration onto existing infrastructure reduces the racking and installation cost. In this work, we investigate routes to improve the efficiency of transparent solar cells by utilizing multijunction architectures. A transfer-matrix optical interference model is developed as a framework to optimize the full device stack considering the angle-dependent PV performance that is critical for matching subcell photocurrents in series tandem solar cells. In addition, a new method of fine tuning energy levels of low-bandgap small molecules with infrared selective absorption was demonstrated using a series of organic heptamethine salts. By exchanging the counterion from a small, hard anion to a fluorinated weakly coordinating anion, the frontier energy of the salt is shown to shift without affecting the bandgap, thus enabling simultaneous optimization of photocurrent generation of photovoltage. We further utilize this tunability to develop heptamethine molecules with absorption as deep as 1600 nm, the deepest infrared photo-response demonstrated to date with organic small molecules ideal for multijunction integration. Ultimately, transparent solar cells are an exciting new paradigm for solar deployment enabled by organic and excitonic semiconductors that offer a pathway to integrate solar onto virtually any surface without impacting the view."--Page ii.
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Title: Transmission timing modulation for information coding in energy-constrained wireless networks
Creator: Feng, Dezhi
Date: 2020
Collection: Electronic Theses & Dissertations
Description: The objective of this thesis is to develop a framework of transmission timing-based modulation framework for improving energy efficiency, security, and information transfer capacity in embedded wireless networks with very thin energy budgets. The key idea is to modulate both intra-PDU (Protocol Data Unit) and inter-PDU timing for addressing energy, security, and information transfer capacity in wireless embedded networks. As for energy efficiency, we developed a novel pulse position-coded PDU...
Show moreThe objective of this thesis is to develop a framework of transmission timing-based modulation framework for improving energy efficiency, security, and information transfer capacity in embedded wireless networks with very thin energy budgets. The key idea is to modulate both intra-PDU (Protocol Data Unit) and inter-PDU timing for addressing energy, security, and information transfer capacity in wireless embedded networks. As for energy efficiency, we developed a novel pulse position-coded PDU (PPCP) paradigm. The core idea is to encode a protocol data unit (PDU) in terms of the silence duration between two sets of delimiter pulses, whose positions are modulated based on the value of the PDU. This PPCP architecture achieves significant energy savings by using a lesser amount of bit/pulse transmissions, and by eliminating long multi-bit preambles and headers, which are normally used in traditional packets. The proposed multi-access pulse-based PDU scheme enables medium sharing among many sensor nodes without requiring per-PDU frame synchronization. As for security, we developed the concept of a novel chaotic pulse position coded protocol data unit (CPPCP) for secure embedded networking. The core idea of CPPCP is to encode a protocol data unit (PDU) with a wideband pulse train with chaotically-varied inter-pulse intervals. The architecture ensures communication security by introducing randomness between data symbols, noise-like frequency spectrum, and significant energy savings by using a smaller number of pulse transmissions compared to existing secure coding schemes such as Bluetooth Low Energy (BLE). Compared with the traditional key-based cryptographic techniques, CPPCP suppresses decipherable information by eliminating symbol periodicity. The mechanism can also be piggy-backed on traditional cryptography solutions to achieve higher levels of security. Finally, for enhancing the information transfer capacity, we developed a data packet position modulation (DPPM) paradigm. Packet transmissions in low duty cycle networks are often scheduled as TDMA slots, whose periodicity is determined based on application sampling requirements and the energy in-flow, often in the form of energy harvesting. The key idea of DPPM is to modulate the inter-packet spacing for coding additional information without incurring additional transmission energy expenditures. We first developed a have a DPPM based networking solution for single-hop transmit-only networks in which a number of low-energy nodes transmit data to an aggregator. The architecture is developed for a two-node point-to-point link, followed by a multipoint-to-point multi-access network. Detailed analytical and simulation models are developed to demonstrate the performance of a symmetric and an asymmetric version of DPPM.
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Title: Transmissibility and localization of tetrodotoxin in the rough-skinned newt, Taricha granulosa
Creator: Wegener, Sarah (Graduate of Michigan State University)
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Tetrodotoxin (TTX) is a powerful neurotoxin that prevents the propagation of action potentials, leading to paralysis and sometimes death in nearly all animals. However, a diverse group of marine and freshwater animals possess TTX, which they use for offense, defense, and communication. One of most studied TTX-mediated interactions is the predator-prey arms race between the rough-skinned newt (Taricha granulosa) and common garter snake (Thamnophis sirtalis). Variation in toxicity among...
Show more"Tetrodotoxin (TTX) is a powerful neurotoxin that prevents the propagation of action potentials, leading to paralysis and sometimes death in nearly all animals. However, a diverse group of marine and freshwater animals possess TTX, which they use for offense, defense, and communication. One of most studied TTX-mediated interactions is the predator-prey arms race between the rough-skinned newt (Taricha granulosa) and common garter snake (Thamnophis sirtalis). Variation in toxicity among populations of newts matched by TTX-resistance in predatory snakes has captured the focus of much research centered on the hypothesis that the arms race is the sole driver of variation. Nevertheless, recent studies suggest a more complex dynamic. Explanations of the dramatic variation in TTX among different populations of newts can only be constructed once fundamental questions about the origin, function, and transmission of TTX in newts have been more thoroughly explored. In this study, I took two approaches to address the origin, function, and transmission of TTX: 1) a cohabitation experiment in which I paired toxic and non-toxic newts to test whether toxicity can be acquired through contact, and 2) an experiment to determine the distribution and concentration of TTX in different tissues. The cohabitation experiment revealed no detectable change in the toxicity of non-toxic male newts, suggesting that a physical or physiological impediment prevents non-toxic newts from becoming toxic. The tissue toxicity experiment demonstrated that TTX is present throughout the body in structurally and functionally diverse tissues, which has many implications for the involvement of TTX in communication and reproduction in addition to defense."--Page ii.
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Title: Towards machine learning based source identification of encrypted video traffic
Creator: Shi, Yan (Of Michigan State University)
Date: 2019
Collection: Electronic Theses & Dissertations
Description: The rapid growth of the Internet has helped to popularize video streaming services, which has now become the most dominant content on the Internet. The management of video streaming traffic is complicated by its enormous volume, diverse communication protocols and data formats, and the widespread adoption of encryption. In this thesis, the aim is to develop a novel firewall framework, named Soft-margined Firewall, for managing encrypted video streaming traffic while avoiding violation of user...
Show moreThe rapid growth of the Internet has helped to popularize video streaming services, which has now become the most dominant content on the Internet. The management of video streaming traffic is complicated by its enormous volume, diverse communication protocols and data formats, and the widespread adoption of encryption. In this thesis, the aim is to develop a novel firewall framework, named Soft-margined Firewall, for managing encrypted video streaming traffic while avoiding violation of user privacy. The system distinguishes itself from conventional firewall systems by incorporating machine learning and Traffic Analysis (TA) as a traffic detection and blocking mechanism. The goal is to detect unknown network traffic, including traffic that is encrypted, tunneled through Virtual Private Network, or obfuscated, in realistic application scenarios. Existing TA methods have limitations in that they can deal only with simple traffic patterns-usually, only a single source of traffic is allowed in a tunnel, and a trained classifier is not portable between network locations, requiring redundant training. This work aims to address these limitations with new techniques in machine learning. The three main contributions of this work are: 1) developing new statistical features around traffic surge periods that can better identify websites with dynamic contents; 2) a two-stage classifier architecture to solve the mixed-traffic problem with state-of-the-art TA features; and 3) leveraging a novel natural-language inspired feature to solve the mixed-traffic problem using Deep-Learning methods. A fully working Soft-margin Firewall with the above distinctive features have been designed, implemented, and verified for both conventional classifiers and the proposed deep-learning based classifiers. The efficacy of the proposed system is confirmed via experiments conducted on actual network setups with a custom-built prototype firewall and OpenVPN servers. The proposed feature-classifier combinations show superior performance compared to previous state-of-the-art results. The solution that combines natural-language inspired traffic feature and Deep-Learning is demonstrated to be able to solve the mixed-traffic problem, and capable of predicting multiple labels associated with one sample. Additionally, the classifier can classify traffic recorded from locations that are different from where the trained traffic was collected. These results are the first of their kind and are expected to lead the way of creating next-generation TA-based firewall systems.
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Title: Towards interpretable face recognition
Creator: Yin, Bangjie
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Deep CNNs have been pushing the frontier of visual recognition over past years. Besides recognition accuracy, strong demands in understanding deep CNNs in the research community motivate developments of tools to dissect pre-trained models to visualize how they make predictions. Recent works further push the interpretability in the network learning stage to learn more meaningful representations. In this work, focusing on a specific area of visual recognition, we report our efforts towards...
Show moreDeep CNNs have been pushing the frontier of visual recognition over past years. Besides recognition accuracy, strong demands in understanding deep CNNs in the research community motivate developments of tools to dissect pre-trained models to visualize how they make predictions. Recent works further push the interpretability in the network learning stage to learn more meaningful representations. In this work, focusing on a specific area of visual recognition, we report our efforts towards interpretable face recognition. We propose a spatial activation diversity loss to learn more structured face representations. By leveraging the structure, we further design a feature activation diversity loss to push the interpretable representations to be discriminative and robust to occlusions. We demonstrate on three face recognition benchmarks that our proposed method is able to achieve the state-of-art face recognition accuracy with easily interpretable face representations.
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Title: Towards discrete-pulse-based networking and event detection architectures for resource-constrained applications
Creator: Das, Saptarshi (Graduate of Michigan State University)
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "In this dissertation thesis, we develop a scalable and energy-efficient discrete-pulse-based networking architecture along with a Spiking-Neuron-based low-power detection framework for use in resource-constrained settings. Applications such as Structural Health Monitoring (SHM) using wireless sensor networks powered by ambient energy harvesting are particularly suited for such a framework. The key idea in pulse-based networking is to eschew unnecessary overhead as incurred in traditional...
Show more"In this dissertation thesis, we develop a scalable and energy-efficient discrete-pulse-based networking architecture along with a Spiking-Neuron-based low-power detection framework for use in resource-constrained settings. Applications such as Structural Health Monitoring (SHM) using wireless sensor networks powered by ambient energy harvesting are particularly suited for such a framework. The key idea in pulse-based networking is to eschew unnecessary overhead as incurred in traditional packet-based networking and encode only the essential information using small number of discrete pulses and their positions with respect to a synchronized time frame structure. The baseline pulse networking does not scale well with increase in network size. In order to ameliorate this, we develop a scalable time frame structure for use in applications with large network size while preserving the energy advantages of pulse networking. In addition, we stress the importance of judicious use of erratic energy availability in ambient energy harvesting powered systems. To that effect, we build energy-awareness syntaxes within the pulse networking framework for better utilization of energy resources in such systems. We also demonstrate the feasibility of pulse networking over a through-substrate ultrasonic link layer and the advantages thereof in terms of utilizing existing infrastructure and removing the need for radio retrofits. We explore how the protocol performance varies for an airplane stabilizer monitoring application powered by ambient vibration energy harvesting in different energy availability scenarios. Beyond this, we also develop a Spiking-Neuron-based low-power event pattern detection architecture and illustrate how this can be incorporated within a pulse-networked SHM system. The Spiking Neuron based architecture is evidenced to be simpler in terms of implementation but more efficient in terms of computation and energy usage, thus enabling in-situ detection even at intermediate nodes in the network and robust low-power event pattern detection immune to pulse drifts and errors."--Pages ii-iii.
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Title: Towards a community of practice for an informed citizenry : secondary students' sense-making of graphs related to climate change
Creator: Lee, May H.
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Although graphs are used to communicate much of the science-based issues that impact our society (e.g., climate change), citizens often do not make sense of them as intended. To help people become members in a community of competent outsiders, this qualitative study investigates how my participants made sense of three graphs depicting phenomena related to climate change (Keeling, Temperature, and Arctic). The analysis of my participants' interview transcripts and sketches showed that their...
Show moreAlthough graphs are used to communicate much of the science-based issues that impact our society (e.g., climate change), citizens often do not make sense of them as intended. To help people become members in a community of competent outsiders, this qualitative study investigates how my participants made sense of three graphs depicting phenomena related to climate change (Keeling, Temperature, and Arctic). The analysis of my participants' interview transcripts and sketches showed that their sense-making of these graphs could be characterized by one of four approaches (figurative, literal, analytic, and analytic+) with respect to the graphing practices (interpret and analyze, explain, predict, and generalize) and set of crosscutting strategies (stories about how phenomena occur, mathematical strategies, and perceptions of graph sources and uses). The general framework for the graphical sense-making of these three graphs can be used to inform curriculum development, classroom instruction, and assessment design of concepts and practices related to those graphs.
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Title: Towards a Robust Unconstrained Face Recognition Pipeline with Deep Neural Networks
Creator: Shi, Yichun
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Face recognition is a classic problem in the field of computer vision and pattern recognition due to its wide applications in real-world problems such as access control, identity verification, physical security, surveillance, etc. Recent progress in deep learning techniques and the access to large-scale face databases has lead to a significant improvement of face recognition accuracy under constrained and semi-constrained scenarios. Deep neural networks are shown to surpass human performance...
Show moreFace recognition is a classic problem in the field of computer vision and pattern recognition due to its wide applications in real-world problems such as access control, identity verification, physical security, surveillance, etc. Recent progress in deep learning techniques and the access to large-scale face databases has lead to a significant improvement of face recognition accuracy under constrained and semi-constrained scenarios. Deep neural networks are shown to surpass human performance on Labeled Face in the Wild (LFW), which consists of celebrity photos captured in the wild. However, in many applications, e.g. surveillance videos, where we cannot assume that the presented face is under controlled variations, the performance of current DNN-based methods drop significantly. The main challenges in such an unconstrained face recognition problem include, but are not limited to: lack of labeled data, robust face normalization, discriminative representation learning and the ambiguity of facial features caused by information loss.In this thesis, we propose a set of methods that attempt to address the above challenges in unconstrained face recognition systems. Starting from a classic deep face recognition pipeline, we review how each step in this pipeline could fail on low-quality uncontrolled input faces, what kind of solutions have been studied before, and then introduce our proposed methods. The various methods proposed in this thesis are independent but compatible with each other. Experiment on several challenging benchmarks, e.g. IJB-C and IJB-S show that the proposed methods are able to improve the robustness and reliability of deep unconstrained face recognition systems. Our solution achieves state-of-the-art performance, i.e. 95.0\% TAR@FAR=0.001\% on IJB-C dataset and 61.98\% Rank1 retrieval rate on the surveillance-to-booking protocol of IJB-S dataset.
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Title: Toward a sustainable online Q&A community via design decisions based on individuals' expertise : evidence from simulations
Creator: Liang, Yuyang
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Online Q&A communities have become an important channel for internet users to seek information and share knowledge. Existing research extensively focuses on the individual components of Q&A communities, such as content quality and user characteristics, but fails to provide a comprehensive understanding of the communities as complex social systems, whose behavior depends on the interactions of a large number of social agents. In this dissertation, I integrated the key components in online Q&A...
Show moreOnline Q&A communities have become an important channel for internet users to seek information and share knowledge. Existing research extensively focuses on the individual components of Q&A communities, such as content quality and user characteristics, but fails to provide a comprehensive understanding of the communities as complex social systems, whose behavior depends on the interactions of a large number of social agents. In this dissertation, I integrated the key components in online Q&A communities via agent-based modeling to provide a systematic examination of Q&A communities and help inform better community design to manage users' expertise. I conducted computer simulations and virtual experiments based on existing findings and theories as well as data from a large online Q&A community to understand how two design decisions, including expertise indication and question routing, influence the sustainability of a Q&A community as well as result in possible trade-offs involved in implementing these design decisions. Results indicate that these design decisions are likely to lead to a larger membership size and a higher rate of solved questions. In addition, implementing design decisions will also influence the member structure of a community. Question routing tends to prioritize experts' needs and benefits while expertise indication is more likely to attract beginners. These findings suggest that these design decisions should be leveraged according to the development stage a community is in. This research also demonstrates the value of agent-based modeling in terms of generating insights for Q&A community design by showing the underlying structural outcomes of the design decisions.
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Title: Tool Wear Study in Turning Ti-6Al-4V and Edge Trimming of Carbon Fiber Reinforced Plastics (CFRP)
Creator: Khawarizmi, Ryan Muhammad
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Lightweight materials such as titanium alloys and carbon fiber reinforced plastics (CFRP) are highly desirable due to their low density and high strength properties for many aerospace, chemical, petroleum, automotive, and sports applications. However, both materials are considered difficult to machine due to various factors.In machining titanium alloys, the low thermal conductivity and highly reactive nature of titanium with cutting tools cause the temperature to rise quickly, producing a...
Show moreLightweight materials such as titanium alloys and carbon fiber reinforced plastics (CFRP) are highly desirable due to their low density and high strength properties for many aerospace, chemical, petroleum, automotive, and sports applications. However, both materials are considered difficult to machine due to various factors.In machining titanium alloys, the low thermal conductivity and highly reactive nature of titanium with cutting tools cause the temperature to rise quickly, producing a segmented or “saw-tooth” chip. Chip segmentation caused a periodic loading on the tool and affected the cutting process. Ti-6Al-4V depending on the heat treatment, produces four distinct types, elongated (ELO), mill-annealed (MIL), solution treated and aged (STA), and lamellar (LAM). In this dissertation, four different microstructures of Ti64, ELO, MIL, STA, and LAM, are machined at 61, 91, and 122 m/min. The machining chips were collected and characterized to study the impact of the microstructure. In addition, the crater wear for different types of Ti64 was measured and compared. A finite element numerical simulation was developed using the chip morphology measured, which enables estimating the cutting temperature for Ti64-STA. Electron backscatter images of the cutting chips (EBSD) and crater wear surfaces were also analyzed to verify the wear mechanism. The findings suggested a high interface temperature during cutting enables faster tool diffusion. Another machinability study of turning Ti64-STA using a variety of coated tools was conducted. The coated tool materials include TiAlN, AlTiN, AlMgB14(BAM), ZrN, and (AlCrSi/Ti)N. The performance of these cutting tools was assessed using cutting force data, flank wear, and crater wear measurements. In conjunction with the coating experiments, another machining study was conducted in minimum quantity lubrication (MQL) using oil mixed with solid additives such as hBN, WS2, MoS2, and xGnP. For CFRP, the abrasion from the fibers was the leading cause of tool wear. Three distinctly different types of CFRPs with T300 PAN-based carbon fibers as standard modulus (SM), IM-7 PAN-based carbon fibers as intermediate modulus (IM), and K13312 pitch-based carbon fibers as high modulus (HM) are used. Tool wear during the edge-trimming process of three types of CFRP laminates is analyzed for four different ply angles, namely 0°, 45°, 90°, 135°, to investigate the interactions between the fiber type and the fiber orientation.
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Title: To translate a life : understanding the holocaust through autobiographical stories
Creator: Stieren, Amelia Naomi
Date: 2020
Collection: Electronic Theses & Dissertations
Description: This thesis seeks to understand some of the aspects and events of the Holocaust through autobiographical stories, with a particular focus on what it means to translate one's life. As there are many different ways one can learn about the Holocaust, this thesis takes a comparative approach of the works of two authors with very different life circumstances: Ruth Kluger's autobiographical works weiter leben: Eine Jugend, and Still Alive: A Holocaust Girlhood Remembered, and Nora Krug's graphic...
Show moreThis thesis seeks to understand some of the aspects and events of the Holocaust through autobiographical stories, with a particular focus on what it means to translate one's life. As there are many different ways one can learn about the Holocaust, this thesis takes a comparative approach of the works of two authors with very different life circumstances: Ruth Kluger's autobiographical works weiter leben: Eine Jugend, and Still Alive: A Holocaust Girlhood Remembered, and Nora Krug's graphic memoirs Belonging: A German Reckons with History and Home, and Heimat: Ein deutsches Familienalbum. While both authors have in common that they have written their works in both English and German, the lives of these authors are remarkably different: Ruth Kluger is a Jewish survivor of the genocide from Austria, living in the United States, and Nora Krug is neither a survivor nor Jewish, but rather, a German living in the United States with familial ties to Nazi Germany. Nevertheless, in the translation of their lives into their works, both authors raise many questions and concerns about their identity, displacement (forced for Kluger, chosen for Krug), their sense or lack of belonging, and how different aesthetic forms are necessary for them in the constructing of their life narratives, and in tandem with each other, they offer a way to further understand the events of the Holocaust.
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Title: To epenthesize or not? segment insertion in mandarin loanwords
Creator: Huang, Ho-Hsin
Date: 2020
Collection: Electronic Theses & Dissertations
Description: This dissertation investigates segment insertion through two contextualized loanword adaptation processes: intervocalic nasal and coda [m] adaptations, with corpus and experimental data. My research focuses are: 1) to identify the phonological environments of segment insertion in the target adaptation processes in my corpus data, and propose explanations for the insertion patterns in Standard Mandarin loanwords; 2) to verify my arguments with experimental data; 3) to examine whether...
Show moreThis dissertation investigates segment insertion through two contextualized loanword adaptation processes: intervocalic nasal and coda [m] adaptations, with corpus and experimental data. My research focuses are: 1) to identify the phonological environments of segment insertion in the target adaptation processes in my corpus data, and propose explanations for the insertion patterns in Standard Mandarin loanwords; 2) to verify my arguments with experimental data; 3) to examine whether bilingualism affects target segment adaptations; and 4) to discuss what linguistic mechanism controls the adaptation processes.Nasal insertion in Mandarin loanwords is considered an "unnecessary repair" since both English and Mandarin allow a syllable containing consonant-vowel-nasal. However, the existing loanwords show that nasal insertion has strong correlation to the prenasal vowel quality, and the primary word stress location in the source language. To trigger nasal insertion, the English prenasal vowel has to be lax (vowel type condition) and must bear the primary word stress (stress location condition), e.g. Denis → [tan.ni02D0.s02790329]. Nasal insertion rarely occurs when the prenasal vowel is tense or a diphthong, e.g. 02C8Lina → [li02D0.na02D0]. Variable adaptation occurs when the prenasal vowel is [0259], e.g. 02C8Tiffany →[ti02D0.fan.nei] 0303 [ti02D0.fu02D0.ni02D0]. Low back [0251] never triggers nasal insertion, e.g. Ca02C8bana → [kha02D0.pa02D0.na02D0]. I propose that adaptors are sensitive to the fine acoustic cues of the prenasal vowel and stress syllabification pattern. I argue that the "unnecessary repair" is necessary for acoustic cue mapping so the input is perceptually similar to the output.Vowel epenthesis is argued to fix illicit coda [m] in Mandarin, but it is related to syllable location and the following consonant type. It occurs in word-medial and word-final coda positions. It never occurs in homorganic environments with a prenasal lax vowel, e.g. Columbia → [k026402D0.lun.pi02D0ja02D0]. However, with a prenasal diphthong or tense vowel, vowel epenthesis still appears. Variable adaptation is present when coda [m] is in word-medial position followed by an obstruent, e.g. Camden → [kha02D0.mu02D0.t0259n] 0303 [kh0259n.tun]. I propose that vowel epenthesis takes place to preserve all the segmental information, although the output may be perceived as less similar to the input due to an excess vowel. Repairing with [n]/[n] in homorganic environments not only preserves all the underlying features but also leads the output to be more perceptually similar to the input. Both modification methods suggest that coda [m] adaptation is motivated by phonological grammaticality, and acoustic cues play a relatively minor role.33 Mandarin monolingual and 24 Mandarin-English bilingual speakers participated in the experiments. Test item structures followed the corpus generalizations. For intervocalic nasal adaptation, the results from both groups are similar to each other and to the corpus data patterns: participants were sensitive to prenasal vowel quality. Similar results from the two groups further confirm that nasal insertion is more phonetically driven. For coda [m] adaptation, the results from the bilingual participants follow the Preservation Principle, even in homorganic lax vowel environments. The monolinguals repair the coda [m] through epenthesis and nasal place change by chance. I suggest that the coda [m] adaptation process is phonologically driven.This dissertation demonstrates that nasal adaptations in Standard Mandarin are contextualized. Two adaptation processes with essential differences in grammaticality are controlled by different linguistic mechanisms. Intervocalic nasal adaptation supports the perception-based loanword model, whereas coda [m] adaptation supports the phonology-based model.
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Title: Time-domain analysis of fractional wave equations and implementations of perfectly matched layers in nonlinear ultrasound simulations
Creator: Zhao, Xiaofeng
Date: 2018
Collection: Electronic Theses & Dissertations
Description: The attenuation of ultrasound propagating in human tissue follows a power law with respect to frequency that is modeled by several different fractional partial differential equations. These models for the power law attenuation of medical ultrasound have been developed using fractional calculus, where each contains one or more time-fractional or space-fractional derivatives. To demonstrate the similarities and differences in the solutions to causal and noncausal fractional partial differential...
Show moreThe attenuation of ultrasound propagating in human tissue follows a power law with respect to frequency that is modeled by several different fractional partial differential equations. These models for the power law attenuation of medical ultrasound have been developed using fractional calculus, where each contains one or more time-fractional or space-fractional derivatives. To demonstrate the similarities and differences in the solutions to causal and noncausal fractional partial differential equations, time-domain Green's functions are calculated numerically for the fractional wave equations. For three time-fractional wave equations, namely the power law wave equation, the Szabo wave equation, and the Caputo wave equation, these Green's functions are evaluated for water with a power law exponent of y=2, liver with a power law exponent of y=1.139, and breast with a power law exponent of y=1.5. Simulation results show that the noncausal features of the numerically calculated time-domain response are only evident in the extreme nearfield region and that the causal and the noncausal Green's functions converge to the same time-domain waveform in the farfield. When noncausal time-domain Green's functions are convolved with finite-bandwidth signals, the noncausal behavior in the time-domain is eliminated, which suggests that noncausal time-domain behavior only appears in a very limited set of circumstances and that these time-fractional models are equally effective for most numerical calculations.For the calculation of space-fractional wave equations, time-domain Green's functions are numerically calculated for two space-fractional models, namely the Chen-Holm and Treeby-Cox wave equations. Numerical results are computed for these in breast and liver. The results show that these two space-fractional wave equations are causal everywhere. Away from the origin, the time-domain Green's function for the dispersive Treeby-Cox space-fractional wave equation is very similar to the time-domain Green's functions calculated for the corresponding time-fractional wave equations, but the time-domain Green's function for the nondispersive Chen-Holm space-fractional wave equation is quite different. To highlight the similarities and differences between these, time-domain Green's functions are compared and evaluated at different distances for breast and liver parameters. When time-domain Green's functions are convolved with finite-bandwidth signals, the phase velocity difference in these two space-fractional wave equations is responsible for a time delay that is especially evident in the farfield.The power law wave equation is also utilized to implement a perfectly matched layer (PML) for numerical calculations with the Khokhlov - Zabolotskaya - Kuznetsov (KZK) equation. KZK simulations previously required a computational grid with a large radial distance relative to the aperture radius to delay the reflections from the boundary. To decrease the size of the computational grid, an absorbing boundary layer derived from the power law wave equation. Simulations of linear pressure fields generated by a spherically focused transducer are evaluated for a short pulse. Numerical results for linear KZK simulations with and without the absorbing boundary layer are compared to the numerical results with a sufficiently large radial distance. Simulation results with and without the PML are also evaluated, where these show that the absorbing layer effectively attenuates the wavefronts that reach the boundary of the computational grid.
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Title: Time-dependent description of heavy-ion collisions
Creator: Lin, Hao (Graduate of Michigan State Univesity)
Date: 2020
Collection: Electronic Theses & Dissertations
Description: In this thesis, we aim to advance the time-dependent transport theories for the description of heavy-ion collisions, from two perspectives. As an attempt to address multifragmentation in nuclear collisions, we develop a stochastic transport model based on one-body Langevin dynamics. The new model is subsequently tested and benchmarked with a series of other existing models with satisfaction. The model is also applied to address and confirm the so-called "hierarchy effect" observed in the...
Show moreIn this thesis, we aim to advance the time-dependent transport theories for the description of heavy-ion collisions, from two perspectives. As an attempt to address multifragmentation in nuclear collisions, we develop a stochastic transport model based on one-body Langevin dynamics. The new model is subsequently tested and benchmarked with a series of other existing models with satisfaction. The model is also applied to address and confirm the so-called "hierarchy effect" observed in the multifragmentation for certain systems around Fermi energies. Parallel to the development towards a stochastic theory, we also extend an approach based on non-equilibrium Green's function for the description of correlated nuclear systems in one dimension.Firstly, we present a new framework to treat the dissipation and fluctuation dynamics associated with nucleon-nucleon scattering in heavy-ion collisions. The two-body collisions are effectively described in terms of the diffusion of nucleons in viscous nuclear media, governed by a set of Langevin equations in momentum space. The new framework combined with the usual mean-field dynamics, forming the basis of the new stochastic model, can be used to simulate heavy-ion collisions at intermediate energies.Subsequently, as a proof of principle for the new model, we simulate Au + Au reactions 100 MeV/nucleon and at 400 MeV/nucleon and look at observables such as rapidity distribution and flow as a function of rapidity. The results are found to be consistent with other existing models under the same constrained conditions. To demonstrate the model's ability to describe multifragmentation, we also study the formation of fragments in Sn +Sn reactions at 50 MeV/nucleon, and the fragment distribution and properties are discussed and compared to two other models commonly employed for collisions.Next, we move on to tackle the "hierarchy effect" observed experimentally for reactions around Fermi energies. We simulate Ta + Au at 39.6 MeV/nucleon and compare mainly the charge and velocity distributions of the fragments from the QP with experimental data. Our simulation results can reproduce the trends observed in data, and a semi-quantitative agreement can be reached. This is the first time, to our knowledge, that one has succeeded in addressing the "hierarchy effect" with a dynamic model. The simulation of U + C is also discussed.Finally, we present a fully quantum-mechanical model based on non-equilibrium Green's function, with short-range two-body correlations incorporated as an extension. We examine its applications to one-dimensional nuclear systems, such as the preparation and properties of the ground states, the isovector oscillation of symmetric systems and the boosting of a"slab" in a periodic box. In particular, the dissipation brought by two-body correlations and the Galilean covariance of the theory are demonstrated. These studies lay the groundwork for the future exploration of collisions of correlated nuclear systems in one dimension.
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Title: Timber residue supply for bioenergy in the northern tier of the Great Lakes : determinants and availability
Creator: Dulys-Nusbaum, Elena
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Timber residues, a timber byproduct, are a low-cost source of biomass that avoids the environmental and food market consequences of other energy feedstocks. We studied the effect that price, forest species mix, bio-energy attitudes, environmental amenities, and environmental disamenities have on the decision to harvest for non-industrial private forest owners (NIPFs) in northern Michigan and Wisconsin."--from abstract.

Title: Through experiences, from interactions, and by choices over time : how professors at a research university understand and explain the factors that have influenced their teaching
Creator: Steele, Gregory John
Date: 2019
Collection: Electronic Theses & Dissertations
Description: The intent of this study was to understand professors at a research university, and how the environments and individuals they interact with influenced them and their teaching. The primary research question for this study was, "How do professors at a research university understand and explain the factors that have influenced their teaching?" The secondary research question was intended to focus on the institutional factors that had the most influence on a professor and their teaching: "What...
Show moreThe intent of this study was to understand professors at a research university, and how the environments and individuals they interact with influenced them and their teaching. The primary research question for this study was, "How do professors at a research university understand and explain the factors that have influenced their teaching?" The secondary research question was intended to focus on the institutional factors that had the most influence on a professor and their teaching: "What are the most influential factors that affect a professor's teaching at a research institution?"I interviewed 15 award-winning professors from Michigan State University (MSU) about how they had been prepared, supported, and recognized for their work as teachers. My analysis showed how little preparation the professors received about teaching at a research university, how they relieved more on experience and trusted peers than any of the available campus resources, and how they tended to find personal student recognition more rewarding than their prestigious teaching awards. My results showed how institutional deficiencies (the lack teaching preparation, applicable resources, and sufficient recognition) created obstacles for the professors to overcome as they progressed and developed as teachers. To lessen or remove the institutional obstacles, I recommend research universities better assess and recognize a professor's teaching, faculty developers localize their available resources to the individual colleges and departments, and professors utilize their peers and self-reflection as a way to meet their needs and expectations as teachers. Professors at research universities are expected to prioritize their teaching and scholarship, but the importance of the former can become complicated when institutions place a greater emphasis on the latter (via the tenure process, promotions, raises, and rewards). This study extends previous scholarship which shows that professors at research universities are not sufficiently prepared, supported, or recognized for their work as teachers. If the individual institutions do not properly prepare their professors as teachers, then there is uncertainty as to how, where, and why the individual professors succeed and develop as teachers.
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Title: Three essays on the causes and consequences of youth migration in Tanzania
Creator: Moskaleva, Evgeniya Alekseevna
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Migration of youth is a prominent phenomenon in Sub-Saharan Africa and in East Africa in particular. International and rural-to-urban migration gained a lot of attention in the older literature, yet internal rural-to-rural migration is the most frequent type. This work revolves around several issues of internal migration of youth in rural Tanzania. First, I determine which factors are associated with destination decisions made by young people. I look at four to six destination types on the...
Show moreMigration of youth is a prominent phenomenon in Sub-Saharan Africa and in East Africa in particular. International and rural-to-urban migration gained a lot of attention in the older literature, yet internal rural-to-rural migration is the most frequent type. This work revolves around several issues of internal migration of youth in rural Tanzania. First, I determine which factors are associated with destination decisions made by young people. I look at four to six destination types on the rural-urban spectrum and consider various individual, household, and community factors that could affect migration decision. Second, I test how does migration to various destination areas on the rural-urban spectrum contribute to structural transformation through the shifts in main occupation. Although focusing on the shifts from agricultural work to self-employment and wage job, I also consider other employment categories like students, those working mainly in household maintenance, and unemployed people. Third, I estimate the impacts of youth outmigration on the livelihood of non-migrant household members. I consider changes to the labor supplied to the household farm, attraction of new household members, and adjustments to household participation in labor and land markets.I make contribution to the literature on internal migration of youth in Sub-Saharan Africa, and Tanzania in particular, in four ways. First, I distinguish several migration destinations across the rural-urban spectrum, from low-density rural areas to cities, broadening the conceptualization of migration decision instead of focusing on a specific flow of migrants. I test three categorizations of location types to account for different interpretations of results and to verify that the main results are not an artifact of the choice of the definition of “rural”. Second, I stress the importance of rural-to-rural migration, which is prevalent in Tanzania, although understudied. I show that even migration to low-density rural areas is associated with a shift towards non-agricultural employment. Third, while looking at occupational shifts, I consider people who are usually excluded from the analysis: students and those employed in household maintenance. I also look at women who state marriage as their main reason for migration. It allows to broaden the view on migration flows and discover employment difficulties for certain groups of people, for example, female rural-to-rural migrants involved mainly in household maintenance and students transitioning into employment. Fourth, I explore the labor adjustment strategies of the households left behind after a young adult migrates, which has rarely been studied in the context of the countries of Sub-Saharan Africa.
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