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Title: CROSS-ETHNIC VARIATION IN THE RELATION BETWEEN PARENT AND CHILD BEHAVIORS AND YOUNG CHILDREN’S ACADEMIC AND SOCIAL FUNCTIONING
Creator: Bae, Hyo
Date: 2011-04-20, 2011-05
Description: The aim of this study was to determine if there is cross-ethnic variation in the relationships between parent behaviors, child behaviors, and...
Show moreThe aim of this study was to determine if there is cross-ethnic variation in the relationships between parent behaviors, child behaviors, and young children’s academic and social functioning. Participants included 96 African American, 117 Hispanic, and 395 White 5-year-old children and their parents. Self-reported parenting (Support/Engagement and Hostility/Coercion) was assessed with the Parent Behavior Inventory. Observed parent (Scaffolding) and child behaviors (Engagement/Persistence) were assessed using the Three Boxes Task videotaped parent-child interaction paradigm. Children’s academic skills were measured with three subtests of the Woodcock-Johnson Tests of Achievement-3rd Edition (Letter-Word Identification, Passage Comprehension, and Quantitative Concepts), and their social skills were measured with the Social Skills Rating System. Results of moderated regression analyses indicated that there were no direct effects of parenting on academic achievement, but that child Engagement/Persistence was related to academic achievement. With regard to social skills, Support/Engagement was related to Cooperation, Assertion, Responsibility, and Self-Control, while Hostility/Coercion was related to Cooperation, Responsibility, and Self-Control. Scaffolding was not directly related to social skills. Also, these analyses showed that the majority of these relationships were invariant across ethnic groups, with only a few significant interaction effects. Specifically, higher levels of Scaffolding were related to higher reading scores for African American children, while Scaffolding was not related to reading for White children. Although higher levels of Hostility/Coercion were related to lower reading scores for White children, this relationship was not significant for Hispanic children. Higher levels of Scaffolding were related to higher math scores for African American children. For White children, however, higher levels of Scaffolding were related to lower math scores. There were no ethnic differences in the relation between parent and child behaviors and social skills. Finally, results indicated that Scaffolding was indirectly related to academic and social functioning through Engagement/Persistence, and there was no ethnic variation in these relationships across African American, Hispanic, and White children. The implications of these findings and future directions for research are discussed.
Ph.D. in Psychology, May 2011.
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Title: ALTERNATIVE APPROACH TO VOLATILITY FORECASTING AND EVALUATING FORECASTING PERFORMANCE
Creator: Lim, Hyungjin
Date: 2012-10-08, 2012-12
Description: Studies in the volatility process of financial markets have focused more on volatility modeling aspects, using parametric assumptions....
Show moreStudies in the volatility process of financial markets have focused more on volatility modeling aspects, using parametric assumptions. Compared with the vast amount of research in parametric modeling, there is a lack of studies in nonparametric approaches in volatility forecasting and forecasting performance evaluation. This research intends to explore alternative approaches to forecasting volatility of financial returns, and evaluation of forecasting models. This research will employ grammatical evolution to propose a hybrid forecasting model that utilizes the benefits of parametric and genetic programming models. Furthermore, an alternative methodology to handle structural breaks in volatility is examined by utilizing an adaptive approach in dynamic environments. In an extensive empirical study, the proposed models will be compared with the other models widely used in the literature using statistical and economic tests. Specifically, as an alternative to the statistical performance evaluation measure, a nontraditional method derived from the idea of speculating on asset volatility will be employed to compare the performance as well as to assess economic usefulness of competing volatility models. The hybrid model provided superior forecasting performance than traditional techniques both on economic and statistical measures.
PH.D in Management Science, December 2012
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Title: THEORETICAL ANALYSIS OF REAL-TIME SCHEDULING ON RESOURCES WITH PERFORMANCE DEGRADATION AND PERIODIC REJUVENATION
Creator: Hua, Xiayu
Date: 2017, 2017-07
Description: In 1973, Liu and Layland [81] published their seminal paper on schedulability analysis of real-time system for both EDF and RM schedulers. In...
Show moreIn 1973, Liu and Layland [81] published their seminal paper on schedulability analysis of real-time system for both EDF and RM schedulers. In this work, they provide schedulability conditions and schedulability utilization bounds for both EDF and RM scheduling algorithms, respectively. In the following four decades, scheduling algorithms, utilization bounds and schedulability analyses for real-time tasks have been studied intensively. Amongst those studies, most of the research rely on a strong assumption that the performance of a computing resource does not change during its lifetime. Unfortunately, for many long standing real-time systems, such as data acquisition systems (DAQ) [74, 99], deep-space exploration programs [120, 119] and SCADA systems for power, water and other national infrastructures [121, 26], the performance of computational resources suffer notably performance degradations after a long and continuous execution period [61]. To overcome the performance degradation in long standing systems, countermeasures, which are also called system rejuvenation approaches in the literature [123, 61, 126], were introduced and studied in depth in the last two decades. Rejuvenation approaches recover system performance when being invoked and hence benefit most long standing applications [30, 102, 11, 12, 39]. However, for applications with real-time requirements, the system downtime caused by rejuvenation process, along with the decreasing performance during the system’s available time, makes the existing real-time scheduling theories difficult to be applied directly. To address this problem, this thesis studies the schedulability issues of a realtime task set running on long standing computing systems that suffers performance degradation and uses rejuvenation mechanism to recover. Our first study in the thesis focus on a simpler resource model, i.e. the periodic resource model, which only considers periodic rejuvenations. We introduce a method, i.e., Periodic Resource Integration, to combine multiple periodic resources into a single equivalent periodic resource and provide the schedulability analysis based on the combined periodic resource for real-time tasks. By integrating multiple periodic resources into one, existing real-time scheduling researches on single periodic resource can be directly applied on multiple periodic resources. In our second study, we extend the periodic resource mode to a new resource model, the P2-resource model, in our second work to characterize resources with both the performance degradation and the periodic rejuvenation. We formally define the P2-resource and analyze the schedulability of real-time task sets on a P2-resource. In particular, we first analyze the resource supply status of a given P2-resource and provide its supply bound and linear supply bound functions. We then developed the schedulability conditions for a task set running on a P2-resource with EDF or RM scheduling algorithms, respectively. We further derive utilization bounds of both EDF and RM scheduling algorithms, respectively, for schedulability test purposes. With the P2-resource model and the schedulability analysis on a single P2- resource, we further extend our work to multiple P2-resources. In this research, we 1) analyze the schedulability of a real-time task set on multiple P2-resources under fixedpriority scheduling algorithm, 2) introduce the GP-RM-P2 algorithm and 3) provide the utilization bound for this algorithm. Simulation results show that in most cases, the sufficient bounds we provide are tight. As the rejuvenation technology keeps advancing, many systems are now able to perform rejuvenations in different system layers. To accommodate this new advances, we study the schedulability conditions of a real-time task set on a single P2-resource with both cold or warm rejuvenations. We introduce a new resource model, the P2-resource with duel-level rejuvenation, i.e., P2D-resource, to accommodate this new feature. We first study the supply bound and the linear supply bound of a given P2D-resource. We then study the sufficient utilization bounds for both RM and EDF scheduling algorithms, respectively.
Ph.D. in Computer Science, July 2017
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Title: CONTRIBUTIONS TO ALGORITHMIC MATROID PROBLEMS
Creator: Huang, Jinyu
Date: 2015, 2015-07
Description: In this thesis, we obtain several algorithms for problems related to matroids, a structure that generalizes the concept of linear independence...
Show moreIn this thesis, we obtain several algorithms for problems related to matroids, a structure that generalizes the concept of linear independence in a vector space and an acyclic subgraph structure in a graph. Matroids have been widely applied in combinatorial optimization, graph theory, coding theory and so forth. Specifically, our results include: In this thesis, we present a constant-competitive online algorithm of the matroid secretary problem for the partition matroids without information of the partition and for the paving matroids. We also introduce the multi-objective matroid secretary problem that extends the matroid secretary problem, in which the weight function is a k-vector w = [w1, · · · , wk]. We show a constant competitive algorithm of the multiobjective matroid secretary problem for the uniform matroids and for the paving matroids. Since bases of a matroid generalize many important combinatorial structures, many counting problems can be expressed as a problem that counts the number of bases of a matroid. An efficient approximate counting algorithm can be designed provided that a rapidly-mixing Markov chain that samples bases of a matroid can be constructed. Let Φ(G) be the conductance of the base-exchange graph G. Matroid- Expansion Conjecture (1989, Mihai and Vazirani) states that Φ(G) ≥ 1 for any base-exchange graph G of a matroid, which implies an FPRAS (fully-polynomial randomized approximation scheme) for counting the number of bases of a matroid. We use λ2, the second smallest eigenvalue of L, the discrete Laplacian matrix of G, to prove the Matroid-Expansion Conjecture for any paving matroid, for any balanced matroid, and for the direct sum of a paving matroid with a balanced matroid. A maximum linear matroid parity set is called a basic matroid parity set, if its size is the rank of the matroid. We show that determining the existence of a common base (basic matroid parity set) for linear matroid intersection (linear matroid parity) is in NC2, provided that there are polynomial number of common bases (basic matroid parity sets). For graphic matroids, we show that finding a common base for matroid intersection is in NC2, if the number of common bases is polynomial bounded. We also give a new RNC2 algorithm that finds a common base for graphic matroid intersection. Finally, we prove that if there is a black-box NC algorithm for PIT (Polynomial Identity Testing), then there is an NC algorithm to determine the existence of a common base (basic matroid parity set) for linear matroid intersection (linear matroid parity).
Ph.D. in Applied Mathematics, July 2015
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Title: ANTI-TUMOR SPLICING: RESTORING THE TUMOR SUPPRESSOR BAX IN MICROSATELLITE UNSTABLE TUMORS
Creator: Haferkamp, Bonnie
Date: 2011-11, 2011-12
Description: Microsatellite instability (MSI) is a hallmark for many tumors, especially colon, endometrial, gastric and bladder. Bax, a tumor suppressor...
Show moreMicrosatellite instability (MSI) is a hallmark for many tumors, especially colon, endometrial, gastric and bladder. Bax, a tumor suppressor and pro-death Bcl-2 family member, is frequently mutated in MSI tumors. A microsatellite mutation produces a frameshift with premature termination, leading to “Bax-negative” tumors. Although low Bax expression in tumors is often associated with poor prognosis, several studies have correlated lack of Bax in MSI tumors with improved prognosis. However, the molecular explanation for this paradox is unknown. Here we show that “Bax-negative” tumors in fact generate a novel family of anti-tumor Bax-MSI isoforms through alternative splicing. The thesis includes two parts. In Chapter One, we fully characterize one Bax-MSI isoform, BaxΔ2. We show that BaxΔ2 is detrimental to cancer cells but through a non-conventional death pathway, with differential sensitivity to chemotherapeutics. In Chapter Two, we present an entire family of Bax-MSI isoforms, and illustrate a potential molecular mechanism behind its production. We show that the frequency of Bax alternative splicing is significantly higher in MSI than non-MSI tumors, and that BaxΔ2 trans splicing requirements are ubiquitous in human cell lines. The discovery of functional Bax isoforms in Bax-mutated tumors may help explain why the apparent loss of Baxα in tumors is sometimes associated with a better prognosis. In addition, the unique sequences of Bax-MSI isoforms can serve as biomarkers for diagnostic and treatment purposes. Importantly, identification of Bax-MSI isoforms will provide a great opportunity from a genetic approach or drug design for treatment of MSI cancer.
Ph.D. in Biology, December 2011
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Title: RUMINATION AS A PROCESS THROUGH WHICH COGNITIVE VULNERABILITIES ARE RELATED TO NEGATIVE AFFECT ON BOTH THE TRAIT- AND STATE-LEVEL
Creator: Hutman, Paul J.
Date: 2017, 2017-07
Description: The purpose of this paper is twofold. First, it reviewed the empirical and theoretical literature on rumination as well as three cognitive...
Show moreThe purpose of this paper is twofold. First, it reviewed the empirical and theoretical literature on rumination as well as three cognitive vulnerabilities (intolerance of uncertainty, positive meta-cognitive beliefs about rumination, and thought suppression) associated with negative emotionality. Second, this paper tested trait- and state-level hypotheses that posit (a) rumination is a mediator that connects the three cognitive vulnerabilities to general negative affect and (b) each cognitive vulnerability has a unique relationship to rumination. Rumination is a transdiagnostic and passive, repetitive thought process known to incite and perpetuate a number of negative emotional states and hinder instrumental behavior (e.g., treatment adherence and social support). Although mainly studied as a trait-like tendency, research studying the act of ruminating found it to be a ubiquitous process, experienced as self-focused, unpleasant, and uncontrollable. Ruminating has a number of precipitants (cognitive avoidance, experiencing acute stress, and receiving negative feedback), occurs more often in those experiencing depression, and is associated with inciting or exacerbating negative emotional states (regardless of one’s diagnostic status). To test hypotheses, data was gathered from 77 adults, half reporting a mental health diagnosis, who reported on the intensity with which they experience the cognitive vulnerabilities, rumination, and negative affect on both the trait- and state-level. Findings support rumination as a process through which cognitive vulnerabilities are connected to negative emotionality. Findings indicate all cognitive vulnerabilities were uniquely predictive of rumination when measured as a trait, but only thought suppression uniquely predicted the act of ruminating. Emphasis was placed on discussion of the theoretical and clinical implications of these findings and potential directions for future research.
Ph.D. in Psychology, July 2017
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Title: DYNAMIC ANALYSIS OF UNCERTAIN STRUCTURES USING IMPRECISE PROBABILIY
Creator: Bergerson, Joshua D.
Date: 2014, 2014-05
Description: A new method for dynamic response spectrum analysis of structures with uncertainty in their mechanical properties utilizing the notion of...
Show moreA new method for dynamic response spectrum analysis of structures with uncertainty in their mechanical properties utilizing the notion of imprecise probability is developed. This finite-element-based method is capable of obtaining probabilistic bounds of the dynamic response of the structure with uncertainty defined by enveloping p-boxes. The developed method obtains probabilistic bounds on 1) the mode shapes, 2) modal coordinates, and 3) modal participation factor, leading to the p-boxes of modal responses. Finally maximum modal responses are combined to obtain the structure’s maximum total response with consideration of uncertainty. Numerical examples demonstrating the developed method are included. Keywords: Structural Dynamics, Uncertainty, Imprecise Probability, P-Box.
PH.D in Civil Engineering, May 2014
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Title: PREDICTING CORTICAL RESPONSE DURING TRANSCRANIAL MAGNETIC STIMULATION IN HUMANS
Creator: Krieg, Todd
Date: 2014, 2014-07
Description: Transcranial magnetic stimulation (TMS) is capable of noninvasively activating neurons in the brain. TMS can induce persistent effects and is...
Show moreTranscranial magnetic stimulation (TMS) is capable of noninvasively activating neurons in the brain. TMS can induce persistent effects and is being increasingly used in both clinical and research applications. Despite this growing interest, the relationship between TMS-generated electric fields (E-fields) and specific cortical electrophysiological responses is not well understood. Most analytical approaches focus on applied magnetic field strength in the target region as the primary factor, placing activation on the gyral crowns. However, imaging studies show cortical targets are typically located in the sulcal banks. To study this causal relationship, we combined subject-specific detailed finite element modeling (FEM) to calculate induced E-field information and employed concurrent TMS-PET data as a measure of cortical response. The research presented in this work is divided into three main parts, each one building on the results of the previous: (1) We determined that neocortical surface orientation was a critical determinant of regional activation by studying the locations of activation during TMS on the cortical surface. Results indicated that brain activations were primarily sulcal for both the TMS and task activations. This study provided further evidence that a major factor in cortical activation during TMS is the orientation of the cortical surface with respect to the induced E-fields. This was demonstrated by the fact that the sulcal bank of the primary motor cortex had larger cerebral blood flow (CBF) responses during TMS despite the gyral crown of the cortex being subjected to a larger magnetic field magnitude. (2) We sought to determine the E-field characteristics that lead to cortical activation. We found that decomposing the E-field into orthogonal vector components based on the cortical surface geometry (and hence, cortical neuron directions) led to significant differences between the regions of cortex that were active and non-active. Specifically, active regions had significantly higher E-field components in the normal orthodromic direction (i.e., parallel to pyramidal neurons in the dendrite-to-axon orientation) and in the tangential direction (i.e., parallel to interneurons) at high spatial gradient. In contrast, nonactive regions had higher E-field vectors in the antidromic normal direction. This provides important new understanding of the factors by which TMS induces cortical activation necessary for predictive and repeatable use of this noninvasive stimulation modality. (3) Finally, two different but related algorithms were formulated using different optimization approaches that provide a means for predicting topographical maps of cortical activation in humans. This is the first study to produce an algorithm for predicting the electrophysiological responses of neurons in the cortex based on both gross and microscopic brain anatomy correlated to relevant experimental recordings. This new innovation could provide an invaluable tool for predicting regions of cortical activation that may permit, among other benefits, improved prescriptive TMS protocols to optimize therapeutic response to TMS treatment.
Ph.D. in Biomedical Engineering, July 2014
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Title: AN AUTOMATED ENGINEERING PROCESS TO VERIFY THE CORRECT COORDINATION OF MULTILAYER RECOVERY
Creator: Kroculick, Joseph
Date: 2017, 2017-05
Description: Recovery is a critical function in backbone networks. The primary function of recovery is to provide connectivity regardless of which layer...
Show moreRecovery is a critical function in backbone networks. The primary function of recovery is to provide connectivity regardless of which layer recovery operates at. Another function of recovery is for all services traversing a failed link to be restored in a way that is consistent with a service user’s requirements. These requirements can include the consideration of factors such as (1) the cost of recovery, (2) the amount of traffic restored, and (3) the delay in restoring units of traffic. With more options available to recover traffic, providing an integrated recovery solution is necessary. An important force driving the evolution of network devices to transport services such as IP traffic is the layering of network resources. Layering enables networks to increase capacity by extending legacy SONET networks to interface with optical wavelengths. Inconsistent provisioning can prevent service continuity from being achieved during a failure. Continuity of service has been recognized as one key business goal. Furthermore, since recovery can occur at a different time than when it is provisioned, inconsistent provisioning is determined after the fact, with services left unrepaired, repaired unnecessarily at an extra cost, or not repaired fast enough. A network manager can check if recovery is consistent with a global perspective on how traffic should be restored by comparing the provisioning at each device against suitable properties of a formal representation. To address this issue an engineering method was developed to detect errors in provisioning automated recovery processes in multilayer and multiprotocol transport networks. This dependability assessment process (DAP) leverages inference techniques provided by Semantic Web technologies in order to detect network-device provisioning errors. Provisioning should be accompanied by methodologies, processes, and activities to ensure that it can be trusted to achieve a desired network state. The DAP takes into account unique constraints in the telecommunications domain including bottom-up evolution of physical layer technologies to provide connectivity, and lack of a universal model of network functionality. This method is applied to assessing the correctness of provisioning decisions for a protection switching application in a transport network in both the spatial and temporal domains.
Ph.D. in Computer Science, May 2017
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Title: ANANALYSIS OF ZOO AND AQUARIUM PROVIDED TEACHER PROFESSIONAL DEVELOPMENT
Creator: Kubarek-sandor, Joy
Date: 2014, 2014-12
Description: Informal science institutions are a significant provider of science teacher professional development. As pressure continues to critically...
Show moreInformal science institutions are a significant provider of science teacher professional development. As pressure continues to critically analyze the work of teachers and their effectiveness in the classroom, it is important to understand how informal science institutions contribute to effective change in teacher science content knowledge and pedagogy. This research study analyzed zoo and aquarium provided teacher professional development to respond to the research questions: How do zoos and aquaria determine and assess their goals for teacher professional development? How do these goals align with effective teacher change for science content knowledge and pedagogy? Theoretical frameworks for high quality teacher professional development, effective evaluation of teacher professional development, and learning in informal science settings guided the research. The sample for the study was AZA accredited zoos and aquariums providing teacher professional development (N=107). Data collection consisted of an online questionnaire, follow-up interviews, and content analysis of teacher professional development artifacts. Analysis revealed that by and large zoos and aquariums are lacking in their provision of science teacher professional development. Most professional development focuses on content or resources, neglecting pedagogy. Assessments mismatch the goals and rely heavily on self-report and satisfaction measures. The results demonstrate a marked difference between those zoos and aquariums that are larger in capacity versus those that are medium to small in size. This may be an area of research for the future, as well as analyzing the education resources produced by zoos and aquariums as these were emphasized heavily as a way they serve teachers.
Ph.D. in Mathematics and Science Education, December 2014
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Title: ASSESSING THE CULTURAL SENSITIVITY OF THE BOSTON NAMING TEST-2: IS THERE EVIDENCE FOR DIFFERENTIAL ITEM FUNCTIONING BETWEEN AFRICAN AMERICAN AND CAUCASIAN ADULTS AND BETWEEN MEN AND WOMEN?
Creator: Benson, Laura M.
Date: 2014, 2014-07
Description: The Boston Naming Test – 2 (BNT-2) is one of the most widely used neuropsychological measures for the detection of naming deficits. However,...
Show moreThe Boston Naming Test – 2 (BNT-2) is one of the most widely used neuropsychological measures for the detection of naming deficits. However, there are few studies that have investigated its item-level psychometric properties, particularly in ethnic minorities, including African Americans. The present study examined the BNT-2 for the presence of ethnicity and genderbased differential item functioning (DIF) in a cognitively diverse sample of 744 African American and Caucasian adults recruited from a neuropsychology outpatient clinic in Chicago, Illinois. Using a two-parameter Item Response Theory (IRT) framework, all 60 items of the BNT-2 were analyzed, with difficulty and discriminability estimates generated for items 16 through 60 for ethnicity, and for items 11 through 60 for gender. Ethnicity-based DIF was detected for 10 items (i.e., “globe,” “beaver,” “dominoes,” “unicorn,” “accordion,” “latch,” “tripod,” “yoke,” “trellis,” and “palette”) and genderbased DIF for 6 items (i.e., “stethoscope,” “pyramid,” “latch,” “sphinx,” “yoke,” and “palette”), indicating that these items do not function equivalently between groups, despite being matched on naming ability. Post hoc hierarchical logistic regression analyses examined age, years of completed education, and literacy (measured as word reading ability) as potential explanatory factors for the observed DIF. Results indicated that the three variables provided partial explanations for the DIF detected in the 16 ethnicity and gender items, though none could entirely account for the observed findings. IRT-estimated difficulty parameters also allowed for the examination of item ranking on the BNT-2. For both ethnicity and gender, the IRT-estimated rank ordering of items between groups was similar, as well as being comparable (though not identical) to those initially assigned by Kaplan, Goodglass, and Weintraub (2001). Results further indicated that correlations between BNT-2 scale scores and IRT-based scale scores were very high, suggesting that the overall scoring of the BNT-2 was not subtantially biased by ethnicity or gender, despite the identified DIF and small fluctuations in item rankings. Overall, this implies that the BNT-2 is still a valid measure for use in African Americans, although future consideration should be given to revision or omission of those items identified as having DIF.
Ph.D. in Psychology, July 2014
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Title: DEVELOPING ALGORITHMIC TRADING STRATEGIES AND EMPIRICAL ANALYSIS WITH HIGH FREQUENCY TRADING DATA
Creator: Lee, Jeonghoe
Date: 2015, 2015-07
Description: The PhD dissertation research topics aim at developing algorithmic trading strategies and demonstrating data analysis skills. To be a...
Show moreThe PhD dissertation research topics aim at developing algorithmic trading strategies and demonstrating data analysis skills. To be a quantitative analyst as well as an academic scholar in financial trading area, these two professional backgrounds are indispensable. In detail, chapter 1 shows multi-objective optimization and spontaneous optimization of design variables. For instance, while conventional trading systems explore a single objective function, multi-objective optimization allows us to manage the essential trade-off among profit, standard deviation and maximum-drop. In addition, design parameters such as trading volume, the amount of historical data, and trading gateways of technical indicators are continuously optimized in real time. In chapter 2, this chapter shows an algorithmic trading system with the concept of machine learning, and demonstrating its various applications. The main purpose of this research is to propose objective numerical development framework in algorithmic trading. Chapter 3 pursues understanding liquidity measures which are critical for algorithmic traders and investors. Various liquidity measures have been suggested and they have different sensitivities to the market. This research analyzes liquidity measures and clarifies the relation between market price return & realized volatility and liquidity measures. In sum, with these three chapters, this dissertation will demonstrate necessary research topics in algorithmic trading.
Ph.D. in Management Science, July 2015
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Title: STABILITY OF AQUEOUS FOAMS: FOAM FILM STRATIFICATION PHENOMENON AND THE EFFECTS OF DISPERSED VERSUS SOLUBILIZED OIL
Creator: Lee, Jongju
Date: 2016, 2016-05
Description: A foam is a system consisting of a concentrated dispersion of gas bubbles in a liquid. Foams are encountered in many industries such as food,...
Show moreA foam is a system consisting of a concentrated dispersion of gas bubbles in a liquid. Foams are encountered in many industries such as food, agriculture, chemicals, petroleum, and paper manufacturing. Aqueous foams are formed by using surfactants or nano-colloidal particles. Thin liquid films containing surfactant micelles or other nano-colloidal particles are considered to be the key structural elements of foams containing gas and liquid. We thus probed the effects of the micellar concentration and the film size (area) on the stability of a dry bulk foam by studying the stability of a single foam lamella containing micelles; this is so we can establish the importance of the micellar structuring phenomenon and the foam film size (area) affecting the bulk foam stability. The film stratification phenomenon (stepwise film thinning) was experimentally observed by the reflected light microinterferometry. The stepwise layer-by-layer decrease of film thickness is due to the appearance and growth of dark spot (of one layer less film thickness) in the film. We used the two-dimensional diffusion model to model the dynamics of dark spot expansion considering the apparent diffusion coefficient and the film size. Based on this model, we carried out a parametric study depicting the effects of film thickness (or the number of micellar layers) and film area on the rate of dark spot expansion. Many practical applications involving three-phase foams (aqueous foams containing oil) commonly employ surfactants at several times their critical micelle concentration (CMC). We investigated the influence of both the dispersed and solubilized oils, and the surfactant concentration (above CMC) on the stability of an aqueous foaming system. In foam stability, the relative importance of the dispersed oil versus oil solubilized within the micelles depends on the stability of the aqueous asymmetric (i.e., pseudoemulsion) film between the oil and the air-water interface and the second virial coefficient. Also, the micellar structuring phenomenon tests using the single foam lamella revealed that the multi-layering structure was well pronounced in the absence of the solubilized oil; as a consequence, the foam lamellae thinned slowly layer-by-layer and the oil solubilized in micelles weakened the micellar structure formation. The foam lamellae thinned faster, making the foam less stable.
Ph.D. in Chemical Engineering, May 2016
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Title: HYBRID METHODS FOR SIMULATION OF MUON IONIZATION COOLING CHANNELS
Creator: Kunz, Josiah D.
Date: 2017, 2017-05
Description: COSY Infinity is an arbitrary-order beam dynamics simulation and analysis code. It can determine high-order transfer maps of combinations of...
Show moreCOSY Infinity is an arbitrary-order beam dynamics simulation and analysis code. It can determine high-order transfer maps of combinations of particle optical elements of arbitrary field configurations. For precision modeling, design, and optimization of next-generation muon beam facilities, its features make it a very attractive code. New features are being developed for inclusion in COSY to follow the distribution of charged particles through matter. To study in detail some of the properties of muons passing through material, the transfer map approach alone is not sufficient. The interplay of beam optics and atomic processes must be studied by a hybrid transfer map–Monte Carlo approach in which transfer map methods describe the average behavior of the particles in the accelerator channel including energy loss, and Monte Carlo methods are used to provide small corrections to the predictions of the transfer map accounting for the stochastic nature of scattering and straggling of particles. The advantage of the new approach is that it is very efficient in that the vast majority of the dynamics is represented by fast application of the high-order transfer map of an entire element and accumulated stochastic effects as well as possible particle decay. The gains in speed shown in this work are expected to simplify the optimization of muon cooling channels which are usually very computationally demanding due to the need to repeatedly run large numbers of particles through large numbers of configurations. This work describes the development of the required algorithms and their application to the simulation of muon ionization cooling channels. The code is benchmarked against other codes, validated with experimental results, and predicts results for current muon ionization cooling efforts.
Ph.D. in Physics, May 2017
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Title: ACOUSTIC LOCALIZATION OF BREAKDOWN IN RADIO FREQUENCY ACCELERATING CAVITIES
Creator: Lane, Peter
Date: 2016, 2016-07
Description: Current designs for muon accelerators require high-gradient radio frequency (RF) cavities to be placed in solenoidal magnetic fields. These...
Show moreCurrent designs for muon accelerators require high-gradient radio frequency (RF) cavities to be placed in solenoidal magnetic fields. These fields help contain and efficiently reduce the phase space volume of source muons in order to create a usable muon beam for collider and neutrino experiments. In this context and in general, the use of RF cavities in strong magnetic fields has its challenges. It has been found that placing normal conducting RF cavities in strong magnetic fields reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields, it would be helpful to have a diagnostic tool which can localize the source of breakdown sparks inside the cavity. These sparks generate thermal shocks to small regions of the inner cavity wall that can be detected and localized using microphones attached to the outer cavity surface. Details on RF cavity sound sources as well as the hardware, software, and algorithms used to localize the source of sound emitted from breakdown thermal shocks are presented. In addition, results from simulations and experiments on three RF cavities, namely the Aluminum Mock Cavity, the High-Pressure Cavity, and the Modular Cavity, are also given. These results demonstrate the validity and effectiveness of the described technique for acoustic localization of breakdown.
Ph.D. in Physics, July 2016
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Title: MATERIAL INVENTORY CONTROL AND MANAGEMENT SYSTEM IN CONSTRUCTION USING GIS APPLICATIONS AND A "HYBRID" TRACKING SYSTEM
Creator: Le, Kiet Tuan
Date: 2017, 2017-05
Description: Material inventory control and management is simply the process by which an organization is supplied with the goods and services that it needs...
Show moreMaterial inventory control and management is simply the process by which an organization is supplied with the goods and services that it needs to achieve its objectives of buying, storing and moving materials. There are usually plenty of materials in a construction site. A large amount of stored materials can meet unexpected demands, and can prevent future purchases that can be affected by an escalation of material prices. However, a large amount of stored materials can also cause negative impacts such as increased costs for storing redundant inventory, and decreased construction productivity. Therefore, a proper material inventory control and management system is critical for economy and efficiency in construction projects. A material inventory control and management system consists of two main elements: inventory control and inventory management. Inventory control is the process of monitoring the flow of materials on the construction site beginning when materials are received from manufacturers and ending when those materials are used in production. Inventory management is the practice overseeing and managing the ordering, storage and use of materials on the construction site. In this study, an automated material inventory control and management system is developed using Geographical Information System (GIS) applications and a “hybrid” tracking system to identify the need for materials, order, track, transport, store, control the inventory, circulate on site, and incorporate into production. The proposed system allows users to have access to real-time information about the materials on the construction such as: the arrival of materials, the amount of materials received, the status of materials (either in storage area or in-production), and the up-to-date information about site stocks. Furthermore, the system provides users the ability to make correct and timely decisions regarding materials on the construction site.
Ph.D. in Civil Engineering, May 2017
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Title: NEW SOLID AND LIQUID ELECTROLYTES FOR LITHIUM RECHARGEABLE BATTERIES
Creator: Mei, Xinyi
Date: 2016, 2016-12
Description: Currently, rechargeable lithium batteries are widely used in our consumer electronic products, including cell phones, laptop computers, and...
Show moreCurrently, rechargeable lithium batteries are widely used in our consumer electronic products, including cell phones, laptop computers, and cameras and so on. They have extraordinary potential for application in electric and hybrid electric vehicles by their high energy and power density[1]; however, the major challenges include the higher cost, safety issues related to the solvents and conductibility at lower temperatures are still waiting to be fixed. In this Ph.D. thesis, two types of rechargeable lithium batteries: lithium-ion batteries and lithium-sulfur batteries are discussed. Two different approaches are presented, in the direction of achieving an enhanced electrolyte system for rechargeable lithium batteries. One approach is based on the conventional poly (ethylene oxide) (PEO)-based solid polymer electrolyte (SPE) system. The key feature of this approach is the preparation of nanoparticle lithium salts (NPLS) and low lattice energy fluorinated di-lithium salts. The ionic conductivities of these PEO-based SPEs were markedly improved, due to a decrease in the glass transition temperature (Tg) of the polymer. For lithium-sulfur (Li-S) batteries, the polysulfide shuttle (PSS), caused by the dissolution of cathode polysulfide intermediates into the electrolyte, has delivered a mortal blow to nearly every attempt at obtaining a viable Li-S battery. So, another approach involved the strategic design and synthesis of a series of room temperature ionic liquids (RTILs) to prevent PSS: i) Three series of di-cationic ionic liquids (DILs) are synthesis and characterized. DILs-based electrolytes displayed excellent properties, such as non-flammability, high electrochemical stability and thermal stability. ii) Twelve new asymmetric fluorinated RTILs (FRTILs) were also introduced. The FRTILs based electrolytes showed even better properties than DILs-based electrolytes.
Ph.D. in Chemistry, December 2016
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Title: FLOW IN PARTIALLY CONSTRICTED PLANAR CHANNELS - ORIGINS OF VORTEX SHEDDING AND GLOBAL STABILITY OF NAVIER{STOKES SOLUTIONS
Creator: Boghosian, Michael Edward
Date: 2011-04-17, 2011-05
Description: Vortex shedding is a well-known unsteady uid-dynamic phenomenon occur- ring in a variety of ows in nature including stenosed blood vessels. We...
Show moreVortex shedding is a well-known unsteady uid-dynamic phenomenon occur- ring in a variety of ows in nature including stenosed blood vessels. We nd that current hypotheses regarding the origin of vortex shedding do not apply for the inter- nal ow in a partially constricted two-dimensional channel. As a result, we postulate a novel mechanism to explain the origin of vortex splitting and shedding in this ge- ometry. Numerical simulations of the unsteady, two-dimensional, incompressible Navier{ Stokes equations are performed in a channel having a constriction modeled by a two- parameter Gaussian distribution on both channel walls. Reynolds numbers from 1 to 3000 based on inlet half-channel height and mean inlet velocity and constriction ratios of 0:25, 0:5 and 0:75 are considered. The Navier{Stokes solutions are observed to experience a number of bifurca- tions including unsteady behaviour with shear-layer uctuations and vortex shedding downstream of the constriction. A sequence of events is presented describing how a sustained shear layer instability leads to the unsteady vortex shedding phenomenon via a convective instability and a proposed streamwise pressure-gradient mechanism. In addition, a global linear stability analysis is performed on several station- ary Navier{Stokes solutions to determine the long-term temporal behavior of small amplitude perturbations. Finally, the implications of this research on the hemodynamics in the cephalic vein and potential failure of the brachiocephalic stula are addressed.
Ph.D. in Mechanical Engineering, May 2011
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Title: PEDESTRIAN DETECTION AND TRACKING FOR ADVANCED DRIVER ASSISTANCE SYSTEMS
Creator: Mesmakhosroshahi, Maral
Date: 2017, 2017-05
Description: In an effort to reduce driver errors in being the major cause of traffic accidents, there is a lot of research being conducted into the...
Show moreIn an effort to reduce driver errors in being the major cause of traffic accidents, there is a lot of research being conducted into the development of advanced driver assistance systems (ADAS). ADAS is a system aimed at helping the driver in tasks such as pedestrian and vehicle detection, traffic sign recognition and lane detection. Pedestrian detection is one of the major tasks in advanced driver assistance systems (ADAS). Most of the stereo based pedestrian detection algorithms include three major steps: 1. Ground plane estimation 2. Region of interest (ROI) generation 3. Pedestrian classification In this thesis, we present a stereo-based pedestrian detection framework for advanced driver assistance systems by exploiting both color and depth information obtained from a stereo camera installed in a vehicle. In our proposed framework, we first use the vertical gradient of the dense depth map to estimate and discard the ground plane. The boundaries of the ground plane are then searched to detect the pedestrians and the depth values of the boundaries are used to compute the size of the detection windows for detecting pedestrians at different scales. In addition, a depth-based multi-scale ROI extraction method has been proposed to reduce the computation time of ROI extraction. For classifying ROIs to pedestrian and non-pedestrian classes, Histogram of Oriented Gradients (HOG)/Linear support vector machine (SVM) and Integral Channel Features (ICF)/Adaboost are used. To recover the missed pedestrians and improve the detection rate, an ROI tracking algorithm is proposed which incorporates the ROIs extracted from the current frame with theROIs tracked from a reference frame. For additional reduction in search space, we propose a novel algorithm to reduce the number of candidate windows extracted as ROI by taking advantage of the temporal correlation between the adjacent frames. We also propose a method to improve the accuracy of the pedestrian classifi- cation using the aggregated channel features. In this approach, we use the aggregated channel features as our baseline detector and improve it's accuracy using the tanh normalization and Gabor filter. After classification using Adaboost, we use a posi- tive subset of the bounding boxes to classify them again using Convlutional Neural Network to finalize the detection.
Ph.D. in Electrical Engineering, May 2017
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Title: ENSURING SECURITY AND PRIVACY IN BIG DATA SHARING, TRADING, AND COMPUTING
Creator: Jung, Taheo
Date: 2017, 2017-05
Description: We have witnessed huge values of the big data in the last decade, and it is evidential that the data bring large added values to the business...
Show moreWe have witnessed huge values of the big data in the last decade, and it is evidential that the data bring large added values to the business in various areas. Owing to such opportunities, the data collection and archival became one of the most successful business strategies in the industry, and more and more user-generated data are now being acquired, stored, provisioned, and consumed nowadays. Increased collection made human being more closely involved in the life cycle of the big data characterized by the acquisition, storage, provisioning, and consumption, and larger security and privacy challenges emerged. People’s awareness of such threats led to various efforts by the governments, industry, and academia, and our efforts described in this dissertation also belong to them. We have investigated the security and privacy challenges emerging in various parts of the life cycle big data experience nowadays, and I present our major discoveries in this dissertation which are composed of three major parts: (1) security and privacy in storage of big data; (2) theoretic foundations of privacy-preserving data computing; (3) security in big data trading. We addressed new or existing security/privacy threats existing in different parts of the big data life cycle by either leveraging existing works in intelligent ways or by proposing our novel technologies. The contributions of our discoveries cam be summarized as the protection of user privacy and data security while supporting the original functionalities at negligible extra computation/communication/storage overhead.
Ph.D. in Computer Science, May 2017
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