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Title: THE ROLE OF TRANSFER IN ADJUSTMENT: EXAMINING THE SOCIALIZATION PROCESS FOLLOWING NEWCOMER ORIENTATION
Creator: Meredith, Rachel J.
Date: 2018, 2018-05
Description: The purpose of the study was to extend organizational socialization research by exploring the impact of an orientation over time. Orientations...
Show moreThe purpose of the study was to extend organizational socialization research by exploring the impact of an orientation over time. Orientations and their impact have rarely been studied despite their popularity in practice. When viewed through the lens of the training literature, it was hypothesized that strategic orientations have a positive impact on newcomers by increasing transfer and its predictors (i.e., affective and cognitive learning outcomes). Two-hundred and nine newcomers with prior work experience participated by attending an organization-level orientation on their first two days with a new employer. Post-training learning outcomes were gathered immediately after orientation followed by eight weekly assessments of orientation transfer and newcomer adjustment (i.e., role clarity, social integration, values mastery). Using latent growth curve modeling, intraindividual differences in interindividual change in transfer and adjustment were examined and all trajectories were found to significantly vary within the sample. Findings suggest that transfer declines and then levels off around week four and the slower the decline, the greater the rate of adjustment. As predicted, initial levels of orientation transfer mediated the relationship between learning outcomes and rates of adjustment. Future research should continue to explore the role of transfer in newcomer adjustment, particularly to seek predictors of transfer trajectories which were not found in the present study.
Ph.D. in Psychology, May 2018
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Title: NON-ORTHOGONAL MULTIPLE ACCESS SYSTEM BASED ON COMBINATORIAL DESIGN
Creator: Wu, Yuteng Wu
Date: 2018, 2018-05
Description: In this thesis, a new class of multiuser Non-Orthogonal Multiple Access (NOMA) is studied. Overall, the main contributions are listed as...
Show moreIn this thesis, a new class of multiuser Non-Orthogonal Multiple Access (NOMA) is studied. Overall, the main contributions are listed as follows: Firstly, we study a new class of the space-time code (STC) based on a circulant matrix. A diagonal transmission matrix is adopted by utilizing the singular value decomposition (SVD) on the circulant matrix. After that, we present a Multiuser Multidimensional STC. This code expand the previous diagonal transmission matrix to multiple dimensions. Hence it produces a diversity due to the linear combination of all input elements. Two modified constellations are presented aiming at reducing the constellation expansion and the implementation burden. Secondly, a brief survey on state-of-the-art NOMA systems is provided, where their performance in terms of bit error rate (BER), overload capability and spectrum efficiency are compared. Thirdly, we study a NOMA system systematically. Firstly, an uplink NOMA system based on the Steiner Triple System (STS) is presented. A multiuser detection algorithm by using a reduced size vector correlator which will decrease the receiver complexity with an acceptable performance is proposed. Performance-oriented algorithm and overload-oriented algorithm aiming at handling different channel scenarios are studied. After that, we present a novel constellation forming methodology of downlink NOMA system aiming at solving the surjective-only mapping problem in NOMA systems. Compared with other methods by using constellation shaping, phase shifting and power scaling [1-4], our paradigm is capable of providing a new way to solve the surjective-only mapping with low design complexity. As far as we know, this method has not been used before. Finally, the impact of channel estimation error for NOMA system is simulated. The idea behind channel estimation is transmitting the pilot sequence and estimating the channel coefficient based on the received pilot sequence. As a future work, we will work on ARQ, cryptography and optimal designs.
Ph.D. in Electrical Engineering, May 2018
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Title: SHOWROOMING AND BRICK-AND-MORTAR STORES’ MITIGATION STRATEGIES
Creator: Luo, Yilong
Date: 2018, 2018-05
Description: Showrooming is a shopping strategy wherein consumers touch and feel the products in a brick-and-mortar store but purchase the products from an...
Show moreShowrooming is a shopping strategy wherein consumers touch and feel the products in a brick-and-mortar store but purchase the products from an online-exclusive store that offers a lower price. With improvements of IT technology, such as high-speed internet and mobile phone usage, showrooming is now widely used by consumers worldwide. Brick-and-mortal stores have observed and regarded showrooming not only as a threat but also as a cause of their sales decline. Brick-and-mortar stores have adopted strategies such as price matching and loyalty programs to battle showrooming impact to some extent, but not effectively. The main goal and objective of this study is to assess the conditions and parameters most influencing the showrooming phenomenon and its impact on the survival of brick-and-mortar stores, followed by developing model approaches for the design and evaluation of the best strategies to address competition provided by online stores, focusing on the impact of showrooming. The results of theoretical modeling performed in this study suggest that (a) brick-and-mortar stores suffered from showrooming effects; (b) price matching can help brick-and-mortar stores to alleviate showrooming effects only under certain conditions; (c) price matching could negatively impact consumers’ surplus instead of benefiting them due to cost increases due to price matching policy; (d) price matching is a product-specific strategy rather than a store-wide policy; (e) while a manufacturer benefits from the price match policy, it also shares a portion of its profit to motivate offline retailers to offer a price matching policy; and (f) offline retailers can alleviate showrooming effects by strategically carrying parts of the product line. The application of the proposed modeling strategy is presented in two case studies concerning high- and low-cost products.
Ph.D. in Management Science, May 2018
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Title: PA 508 Library Instruction
Creator: Ahrens, Aric G.
Date: 2010-01-15, 2010-01-15
Description: This PowerPoint presentation was given to the Chinese contingent of the Master of Public Administration Graduate Program during Spring...
Show moreThis PowerPoint presentation was given to the Chinese contingent of the Master of Public Administration Graduate Program during Spring Semester 2010. It covers basic research and library skills.
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Title: Lab Safety Manual
Creator: Unknown
Date: 2010, 2010

Title: PA 508 Student Computer Usage Survey: PA 508 Student Survey
Creator: Ahrens, Aric G.
Date: 2010-01-19, 2010-01-19
Description: Included are a survey, and the results in graphic form. The survey was designed to find out how and where the Chinese contingent of Master of...
Show moreIncluded are a survey, and the results in graphic form. The survey was designed to find out how and where the Chinese contingent of Master of Public Administration students used computers. The focus was to determine whether they preferred to use computers on the Downtown Campus, where classes were taught, or on Main Campus, where most of the students lived.
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Title: UNDERSTANDING THE FUNDAMENTAL MECHANISMS OF MESO-SCALE ENGINEERING OF GRAIN BOUNDARIES IN NI-BASE SUPERALLOYS
Creator: Alabbad, Bader
Date: 2019
Description: Polycrystalline nickel base superalloys are known to possess high temperature strength, good crack growth resistance and corrosion resistance...
Show morePolycrystalline nickel base superalloys are known to possess high temperature strength, good crack growth resistance and corrosion resistance at high temperatures. Engineering the morphology of the grain boundaries can yield to extent the high temperature resistance for polycrystalline nickel-based superalloys. Meso-scale engineering for grain boundary structures can be utilized through the development of serrated grain boundaries to improve the damage tolerance of polycrystalline nickel- based superalloys. Grain boundary precipitates induce the formation of the grain boundary serrations as precipitates protrude the grain boundary. Understanding and controlling the cooling processes from above the solvus temperature plays an important role in controlling the size and population of γ′ precipitates to modify specific microstructural features that can impact the resulting properties. Two stepped cooling process with a transition just below the γ′ solvus has the ability to form a unique microstructure as heterogeneous nucleation and growth of large γ′ precipitates along the grain boundaries during the initially slow cooling rate. The eventual transition to a standard or conventional cooling rate will then govern the formation of the secondary, intragranular γ′ precipitates. The stepped cooling process was compared to the conventional fast continuous cooling process. The effect of grain boundary misorientation on the precipitation behavior of grain boundary γ′ precipitates revealed coarse grain boundary γ′ precipitates reside along high angle grain boundaries. Mechanical testing was carried out to investigate their mechanical properties to compare and benchmark to those produced via conventional continuous cooling to quantify the extent by which serrated boundaries can be used to improve the properties where the modified microstructures led to great high temperature properties.Nickel-base superalloy 718Plus is a recently developed alloy that is being considered for use in a number of advanced gas turbine engine applications. A constructed heat treatment was proposed to drive the precipitation of fine η precipitates along grain boundaries. Lamellar η phase precipitates were able to induce the formation of serrated grain boundaries. Discontinuous cellular precipitation reaction led the formation of the lamellar η phase precipitates. The characteristic growth of lamellar η phase precipitates was influence by the grain boundary structure. Creep tests were carried out to provide a better understanding of how serrated grain boundaries formed using η phase precipitates can impact the creep properties of ATI 718Plus.
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Title: Feasibility and Properness in Linear Interference Alignment: Flow Tests, Sufficient Conditions, and Approximation Algorithms.
Creator: Al-Dhelaan, Fahad Abdullah
Date: 2019
Description: Interference forms a major challenge in our understanding of the capacity of wireless networks and our ability to achieve this capacity....
Show moreInterference forms a major challenge in our understanding of the capacity of wireless networks and our ability to achieve this capacity. Rather than scheduling transmissions to avoid interference, recent techniques allow for interference to be neutralized and for simultaneous transmission of messages.Linear interference alignment in MIMO networks is the technique of aligning messages, by the transmitters through the use of precoding matrices, so that the undesired messages occupy some minimal sub-space upon their arrival at an unintended receiver. The overlapping of the sub-spaces where these interfering messages fall allows the receiver to neutralize them with minimal dedication of its resources through the application of a decoding matrix.The linear interference alignment problem is to design these precoding and decoding matrices. It has been shown to be NP-hard in the literature.A network is called feasible if such a solution exists. Even deciding whether some network instance is feasible, is non-trivial. The problem of deciding feasibility was shown to be NP-hard in the literature, for constant channel coefficients.We focus on finding efficient and robust feasibility tests in the case of generic channels, where the computational complexity is unknown. We provide efficient and robust tests for the necessary condition of properness, which had previously been identified in the literature but given no efficient tests in the general case.We identify several conditions, each being sufficient for feasibility. We study their relationships and the computational complexity of testing for them. We provide polynomial-time maximum flow test for one sufficient condition in the case of uniform demands. In the case of uniform demands which divide the number of antennas at all receivers or all transmitters, we show that these sufficient and necessary conditions are equivalent with feasibility, thereby admitting efficient maximum-flow tests.We identify a subset of feasible instances where the decoding and precoding matrices can be designed in polynomial-time. Furthermore, we show that any proper instance is within a constant factor of a one of these instances. Then, we provide efficient constant approximation algorithms for the problems of maximizing demand and minimizing antennas such that an instance is feasible.
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Title: PROVENANCE FOR TRANSACTIONAL UPDATES
Creator: Arab, Bahareh Sadat
Date: 2019
Description: Database provenance explains how results are derived by queries. However, many use cases such as auditing and debugging of transactions...
Show moreDatabase provenance explains how results are derived by queries. However, many use cases such as auditing and debugging of transactions require understanding of how the current state of a database was derived by a transactional history. We introduce an approach for capturing the provenance of transactions. Our approach does not just work for serializable concurrency control protocols but also for non-serializable protocols including snapshot isolation. The main drivers of our approach are a provenance model for queries, updates, and transactions and reenactment, a novel technique for retroactively capturing the provenance of tuple versions. We introduce the MV-semirings provenance model for updates and transactions as an extension of the existing semiring provenance model for queries. Our reenactment technique exploits the time travel and audit logging capabilities of modern DBMS to replay parts of a transactional history using queries. Importantly, our technique requires no changes to the transactional workload or underlying DBMS and results in only moderate runtime overhead for transactions. We discuss how our MV-semirings model and reenactment approach can be used to serve a wide variety of applications and use cases including answering of historical what-if queries which determine the effect of hypothetical changes to past operations of a business, post-mortem debugging of transactions, and to create private data workspaces for exploration. We have implemented our approach on top of a commercial DBMS and our experiments confirm that by applying novel optimizations we can efficiently capture provenance for complex transactions over large data sets.
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Title: SYNTHESIS OF HIGH PERFORMANCE SILICON ANODES AND SURFACE-MODIFIED NMC CATHODES FOR LI-ION BATTERIES
Creator: Ashuri, Maziar
Date: 2019
Description: Lithium-ion batteries (LIBs) have revolutionized the portable electronic devices and electric vehicles (EV) and because of this huge demand,...
Show moreLithium-ion batteries (LIBs) have revolutionized the portable electronic devices and electric vehicles (EV) and because of this huge demand, it is important to meet high power, high specific energy, and long cycle life. All mentioned characteristics are directly related to the choice of anode and cathode electrodes. Currently, graphite is used as anode, while lithium cobalt oxide serves as cathode dominantly. Although graphite can deliver ~ 370 mA h g-1 capacity without significant capacity decay for several cycles, however it is not enough to fulfill the requirements for many applications. Silicon with the theoretical capacity of about 10 times higher than graphite is a promising anode. However, this material suffers from huge volume expansion during cycling in addition to its intrinsic low conductivity. From the cathode viewpoint, the need for materials with less cobalt content is necessary. The resources for cobalt element is very limited while the price of cobalt increasing. Furthermore, cobalt is known as toxic element. Therefore, substitution of cobalt with other elements such as manganese and nickel is necessary. Lithium nickel manganese cobalt oxide (NMC) cathode family materials are introduced following this idea.Here in this thesis, two different approaches are introduced to harness the problems associated with silicon anodes. The first approach is the core/shell design and the second one is the silicon/graphite nanocomposite with tailored structure and engineered voids. Both of these designs can be synthesized easily without complicatedsynthesis steps and harmful chemicals. They have the potential of being commercialized and they do not need expensive equipment. The silicon anodes have been tested successfully in the half-cell coin cells.As for the cathode side, two different members of NMC family materials (NMC333 and NMC532) have been tested. To enhance their electrochemical properties and rate capabilities, a facile surface modification using phosphoric acid was employed. This technique resulted in the formation of thin lithium phosphate coating around the particle. The electrodes performed very well in half-cell configuration. It is expected by utilizing the proposed cathode and anode materials in full-cell set up, a high performance battery with fast charge ability is obtained.
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Title: ECONOMIC MPC-BASED DESIGN AND OPERATION OF GRID SCALE ENERGY STORAGE SYSTEMS
Creator: Adeodu, Oluwasanmi
Date: 2019
Description: It is generally recognized that a higher penetration of renewable power on the electric grid, along with the attendant environmental benefits,...
Show moreIt is generally recognized that a higher penetration of renewable power on the electric grid, along with the attendant environmental benefits, is limited by its inherent high variability and intermittency. An approach to alleviating this issue is to install grid scale energy storage as buffer. However, the economic viability of such an endeavor is dependent on the optimal sizing and placement (OSP) of storage units, which in turn requires the specification of an appropriate storage management policy. While stochastic programming with recourse is recognized as the standard approach to stage-wise optimal decision-making under uncertainty, Economic Model Predictive Control (EMPC) is put forward as a deterministic simplification of the former and demonstrated to be a viable economic dispatch strategy for networks with a high proportion of renewable energy and storage. Then, a numerical, EMPC-based gradient search strategy is proposed to address the OSP problem. Since both the operating policy and OSP questions are invariably massive optimization problems in real systems, strong emphasis is laid on computational tractability. Therefore, the analytical nature of a surrogate stochastic control policy, Economic Linear Optimal Control (ELOC), is exploited to develop innovative modifications to both algorithms. The end products are (1), an Approximate Infinite Horizon EMPC (AIH-EMPC) strategy, a relatively low computational cost variant of EMPC and (2), a hybrid EMPC-ELOC OSP strategy that essentially sidesteps the inherent combinatorial complexity of the unit location problem.
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Title: THE EFFECT OF INTENTIONAL, PERSISTENT SMALL-GROUP LEARNING ON COLLEGE STUDENT ACHIEVEMENT AND RETENTION IN THE PRE-CALCULUS CLASSROOM
Creator: Peterson, Christy Lee
Date: 2019
Description: Various research studies have established that nearly half of all students who decide to pursuit a math, science, or engineering field change...
Show moreVarious research studies have established that nearly half of all students who decide to pursuit a math, science, or engineering field change their mind and seek a different major. The National Center for Education Statistics shows a decrease in the number of degrees in engineering and related fields from 36,900 degrees in the 2003 – 2004 academic year to 31,800 degrees in 2013 – 2014, a 13.8% decline. Not surprising, a report by the President’s Council of Advisors on Science and Technology in 2012 predicted that the United States workforce would see a deficit of one million college graduates in science, technology, engineering and math over the next decade. This study was designed to help answer the question, Is there a difference in achievement or retention for students participating in intentional, persistent small-group learning compared with randomly assigned small-groups in a college level pre-calculus course? This study compared the pre-calculus achievement scores, course pass rates and retention rates between two types of small-group membership, persistent and random. The study also compared students’ study habits throughout the semester and students’ experiences working in a small-group learning environment. Initial examination of the data showed that students participating in intentional, persistent small-groups had better course pass rates and consistently scored higher on unit exams and the final exam than students who participated in randomly assigned small-groups. The course pass rates for both types of small-group membership were similar to the pass rates for students in all other sections of pre-calculus offered at the college. The retention rate for the two courses was similar. However, when compared to the retention rate for all sections of pre-calculus offered at the college, retention was statistically higher in the two sections utilizing small-groups in this study. Given that retention is one of the challenges for pre-calculus, utilizing small-group learning might be a way to improve student retention in college pre-calculus. There were no significant findings for differences in students’ study skills or students’ experiences working in small-group learning environments. However, it was interesting to see that students in randomly assigned small-groups had stronger agreement on items related to working with multiple peers while students in the intentional, persistent small-groups had stronger agreement on items related to developing relationships. The results indicate there might be value to student achievement in utilizing persistent group membership over randomly assigned group membership or even whole-class lecture. Furthermore, the results of this study indicate that utilizing small-group learning in pre-calculus benefits the student retention rate.
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Title: Toward a Comprehensive Atomistic View of Bacterial Outer Membrane Remodeling and Antimicrobial Peptide Susceptibility
Creator: Rice, Amy
Date: 2019
Description: The cell membrane is arguably one of the most important and complex features of a cell, serving to demarcate “self” from “environment” and...
Show moreThe cell membrane is arguably one of the most important and complex features of a cell, serving to demarcate “self” from “environment” and selectively controlling the flow of material in and out of the cell. Bacterial cell membranes are of additional interest since they serve as the first point of contact for antibiotic drugs or other antimicrobial agents. In this work, I use atomistic molecular dynamics simulations to study factors that alter bacterial susceptibility to antimicrobial agents and their environment, with the goal of better understanding how bacteria are able to modulate their sensitivity.First, I present results from a series of simulations of antimicrobial peptides (AMP) interacting with phospholipid bilayers to elucidate the observed interaction differences between arginine and lysine-containing AMPs. Simulations show that the extensive interaction with arginine is due in part to arginine's strong atomic charge distribution, rather than being purely an effect of the greater hydrogen bond capacity. These results highlight the role of charge and hydrogen bond strength in peptide bilayer insertion, and offer potential insights for designing more potent analogues in the future.Next, the effects of bacterial lipopolysaccharide (LPS) modifications are examined, first to understand study how three key modifications observed in S. enterica affect bilayer properties, as well as to examine the role these modifications play in AMP resistance. We hypothesize that defects at the crystalline/liquid-ordered boundary facilitate LL-37 intercalation into the outer membrane, whereas LPS modification protects against this process by having already increased crystallinity and packing efficiency. These results further improve our understanding of outer membrane chemical properties and help elucidate how outer membrane modification systems are able to alter bacterial virulence and susceptibility. Lastly, I investigate the effects of ion type and phosphate charge on four distinct LPS types. Simulations show that bilayer properties are highly influenced by the choice of cation type, ion parameterization, and phosphate group charges. Additional free energy perturbation simulations predict that the protonated LPS state should dominate at physiological pH, in contrast to the deprotonated state utilized by many LPS force fields. Overall, these results reveal inaccuracies in the existing LPS force fields and establish guidelines to better reproduce experimental LPS membrane properties.
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Title: Characterization of the Pseudomonas aeruginosa NQR Complex, a Novel Form of Bacterial Proton Pump, and the Ubiquinone Binding Site
Creator: Raba, Daniel Alexander
Date: 2019
Description: The proton/sodium pumping NADH:Ubiquinone oxidoreductase enzyme complex (NQR) plays a key role in the energy metabolism of a diverse range of...
Show moreThe proton/sodium pumping NADH:Ubiquinone oxidoreductase enzyme complex (NQR) plays a key role in the energy metabolism of a diverse range of bacteria, including pathogenic species such as Vibrio cholera, Pseudomonas aeruginosa, Chlamydia trachomatis, as well as others. Residing in the cytoplasmic membrane of these bacteria, the enzyme couples the transfer of electrons to the pumping of cations across the cell membrane. In all previously studied homologues, the enzyme generates a sodium gradient through its pumping activity that can be utilized by the cell to power essential homeostatic processes. Furthermore, the electrochemical gradient generated by this enzyme has been shown to regulate the production of virulent factors and the efficacy of antibiotic extrusion and elimination. Although certain homologues have been investigated, particularly that of V. cholerae (Vc-NQR), the NQR homologues belonging to important pathogenic species have not been well studied. In the research detailed in this thesis, the first characterization of the NQR of P. aeruginosa (Pa-NQR) is described which identified this homologue as a new form of bacterial proton pump, differentiating it from all other studied homologues of NQR. Additionally, as part of this study our research group characterized the mechanism of inhibition of Pa-NQR by the molecule HQNO which is produced by P. aeruginosa and is known to be a strong inhibitor of Vc-NQR. Our results show that Pa-NQR possesses resistance to inhibition by this molecule compared to Vc-NQR, pinpointing residue F155 of subunit D as being important to resistance and the type of inhibition to be partial-mixed. Moreover, in further developing the understanding of the NQR of V. cholerae, we investigated the binding site of ubiquinone, the final electron acceptor of NQR’s electron transfer process, determining residues P185, L190, and F193 to be important for maintaining the structural composition of the ubiquinone pocket, ensuring efficient substrate binding and catalysis.
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Title: Momentum, Volatility, and Risk-based Allocation
Creator: Qian, Junkai
Date: 2019
Description: This study introduces a coherent framework that links together various momentum measures, market beta, and idiosyncratic risk (IRISK)....
Show moreThis study introduces a coherent framework that links together various momentum measures, market beta, and idiosyncratic risk (IRISK). Momentum is measured as lagged 12-month price momentum (MOM) and volatility adjusted momentum (MOMV). The interaction effect of the three factors is tested. It is found that for 70.64% of the time, a high beta high IRISK stock is more likely to be a top 30% MOM stock than a mid 40% MOM stock. Top MOM exhibits significant bias, 30.81% on average, on high beta high IRISK stocks. Such bias tends to be weaker late in an economy recession. In contrast, top MOMV is less sensitive to high beta and high IRISK. Further, for both MOM and MOMV, it is shown that equally weighted momentum portfolios are driven by high beta high IRISK stocks, especially during a momentum crash. To enhance momentum strategies, risk-based weighting schemes, minimum variance (minVar) and risk parity (ERC), are implemented. In the long run, ERC shows a slight improvement compared to equally weighting, while minVar is able to significantly reduce total risk and tail loss at a cost of sacrifice in performance. A dynamic risk weighting scheme based on changes in market dispersion is proposed to balance the benefit and cost of miVar. Such approach is shown to significantly reduce tail loss and improve Sharpe ratio.
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Title: Improving Methods to Measure the Transport of Outdoor Pollutants into Residential Indoor Environments
Creator: Zhao, Haoran
Date: 2019
Description: Human exposure to ambient pollutants such as particulate matter, ozone, and oxides of nitrogen are associated with a variety of adverse health...
Show moreHuman exposure to ambient pollutants such as particulate matter, ozone, and oxides of nitrogen are associated with a variety of adverse health effects in epidemiology studies. However, much of human exposure to outdoor pollutants occurs inside residential buildings where people spend the majority of their time. One important determinant of indoor exposures to pollutants of outdoor origin is the “penetration factor” of the building envelope, which characterizes the ability of the building enclosure assembly to filter outdoor air as it infiltrates indoors. To date, measurements of envelope penetration factors for various outdoor pollutants in real indoor environments remain extremely limited, in part because current methods suffer from high costs, high uncertainty, and high levels of invasiveness presented to building occupants. Therefore, the research objectives in this dissertation aims to (1) develop and/or refine (as applicable) methods to measure the penetration of outdoor particulate matter, ozone, and nitrogen oxides in buildings and (2) apply them to characterize a diverse sample of residential buildings in Chicago, IL, including single-family homes, multi-family homes, and homes before and after they undergo energy efficiency retrofits. Results from this research will provide refined methods that others can use in field measurements and novel data for modelers to better assess indoor exposures to outdoor pollutants, which can then be used to improve exposure assessments for epidemiology studies.
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Title: Highly Robust Battery-Management System Design for Series Connected Lithium-ion Battery Packs
Creator: Zhang, Yunlong
Date: 2019
Description: Because of the manufacturing variances, the individual cells in a battery pack might have different capacities and be at different levels of...
Show moreBecause of the manufacturing variances, the individual cells in a battery pack might have different capacities and be at different levels of state-of-charge (SOC). Typically, battery balancing in the battery management system (BMS) is the process to equalize the level of SOC of each battery cell in the battery pack. Without effective and appropriate battery balancing, the smallest capacity cell will limit the energy that can be delivered from or charged into the battery pack. Besides, balancing process eliminates the potential of overcharge and overdischarge which is harmful for the battery life cycles and may result in the battery pack explosion. Lithium-ion rechargeable battery cells are rather more sensitive to over-charging/discharging and over-temperature than most commonly used battery chemistries. In this thesis, we proposed the efficiency optimization of the SOC based balancing for series connected lithium-ion battery packs.There are two categories of balancing methods, passive and active. In passive balancing, energy is dissipated through resistors as heat; in active balancing, energy is transferred from the most charged cell(s) to the least charged cell(s) with equalizer(s). Since the balancing efficiency of cell-to-cell (CTC) and cell-to-pack-to-cell (CPC) active methods is higher than any other balancing technique, our optimized balancing scheme in this thesis is implemented based on these two active methods. Because we need to design and manufacture the BMS Printed circuit board (PCB), we have to figure out one optimized balancing circuit by analyzing the different initial SOC distributions and multiple balancing topologies. Not only the minimal energy dissipation of balancing process, but also the structural hazard of different balancing topologies that we need to take into account in the balancing efficiency evaluation for different balancing topologies.OrCAD capture tool from Cadence is the widely used Electronic design automation (EDA) tool to simulate the function of designed real circuit. Because it is too complicated to provided the discrepant control signals for different equalizers in OrCAD, and the simulation runtime of OrCAD will increase exponentially with the increasing number of the balancing equalizers, it is necessary to design one novel computer-aided design (CAD) tool to decrease the simulation runtime for battery packs. Finally, we obtained the optimized balancing circuit by analyzing the balancing circuit efficiency with the novel Matlab based CAD tool. The prototype of BMS PCB we designed consists of microcontroller unit (MCU), Direct current (DC) to DC converter, active balancing circuit, CAN interface and power switches which is used for overcharge and over-discharge protection.
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Title: TWO ESSAYS ON CORPORATE FINANCE AND CAPITAL MARKET
Creator: Zhao, Tianyu
Date: 2019
Description: Two of the most important credit suppliers on the capital market of the United States are commercial banks and online peer-to-peer (P2P)...
Show moreTwo of the most important credit suppliers on the capital market of the United States are commercial banks and online peer-to-peer (P2P) lending platforms. Relaxing restrictions on interstate banking and intrastate branching in banking industry bring more competitions and better efficiency in the banking industry, which provides a much lower cost for firms to raise external funds. We find bank deregulations decrease investment-cash flow sensitivity of firms, which explains the declining trend of investment-cash flow sensitivity since the late 1970s. With the development of internet and transaction technology, online P2P lending platforms become more and more important in the capital market. However, the borrowers on P2P platforms are private individuals with limited official information. We document that when borrower’s official information is limited, social capital, a factor contains region based soft information, plays an important role in effecting online P2P lending activities.
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Title: CYBER PHYSICAL SYSTEM WITH COUPLED NETWORKS: SECURITY AND PRIVACY
Creator: Zhao, Jing
Date: 2019
Description: With the development of cyber physical systems, people and electronic devices are connected via various networks. In many scenarios, different...
Show moreWith the development of cyber physical systems, people and electronic devices are connected via various networks. In many scenarios, different networks are strongly coupled with each other, e.g. power grid is strongly coupled with the communication network in smart grid. On one hand, such coupling brings benefits such as improved efficiency and quick response to system service exceptions. However, the coupling of different networks also brings security and privacy problems. In this thesis we study two scenarios: the the secure coupling of visual connection with short range pairwise communication and privacy aware coupling of smart home with smart grid. For the first scenario, we propose SCsec, a secure screen-camera communication system, which achieves secure one-way communication. The throughput of SCsec is comparable to current screen communication systems. For the second scenario, we propose a novel randomized battery load hiding algorithm which ensures differential privacy for smart homes with smart meters.
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Title: SHARPEN FACTOR INVESTING WITH A CLOSER LOOK AT PROFITABILITY
Creator: Li, Shengsi
Date: 2019
Description: Stock market anomalies have been long researched by academia and used by practitioners. Factor-based allocation has been shown to provide...
Show moreStock market anomalies have been long researched by academia and used by practitioners. Factor-based allocation has been shown to provide better diversification and risk-adjusted returns than the more traditional portfolio approaches. Numerous studies have shown traditional factors such as value, size, and profitability are effective in a cross-sectional fashion, meaning they are effective to all sections. It is found that the factor-return link is not robust across different sectors. Based on this observation, some stylized factor-based investing strategies are refined to improve the return performance measured by risk-adjusted metrics. Further analysis of the firm age moderation effect on the prediction power of profitability over stock return is explored. It is shown that firm age could have a significant moderation effect on the academically proven profitability factor.
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