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Title: FROM EXPLORATION TO RATIONAL DESIGN OF SELECTIVE PROPANE DEHYDROGENATION CATALYSTS
Creator: Hu, Bo
Date: 2015, 2015-12
Description: Light olefins, e.g., ethene and propene, are important building blocks of chemical industry for the production of fuels, polymers, lubricants...
Show moreLight olefins, e.g., ethene and propene, are important building blocks of chemical industry for the production of fuels, polymers, lubricants and other fine chemicals. Due to the rapidly increasing production of shale gas, conversion of small alkanes in the shale gas, e.g., ethane and propane, to their corresponding olefins via alkane dehydrogenation could be an important industrial process. This thesis has focused on exploring the novel single site heterogeneous catalysts for selective alkane dehydrogenation and investigating the general principles of rational catalyst design to achieve a better performing (e.g., more active, more stable, highly selective) dehydrogenation catalyst. Based on the observed reactivity of ZnO for olefin hydrogenation and activity of Zn-ZSM-5 catalysts for alkane activation, catalytic properties of isolated Zn2+ were first explored for propane dehydrogenation. The 3-coordinate Zn in single site Zn/SiO2 catalyst was demonstrated to be the catalytically active species that was highly selective for the generation of propene by propane dehydrogenation. DFT calculations revealed that slow β-hydride elimination of alkyl intermediates limited the overall activity of single site Zn/SiO2 catalyst. Thus, single site Co/SiO2 was also prepared in order to take the advantage of fast β-hydride elimination. The higher activity of single site Co/SiO2 emphasized the potential of transition metals for alkane dehydrogenation, and propane dehydrogenation reactivity of transition metals was further explored by investigating single site Fe/SiO2 catalyst. By comparing with metallic Fe nanoparticles and bulk phase Fe oxides catalysts, the 3-coordinate single site Fe2+ was also suggested to be the catalytically active species for selective propane dehydrogenation. However, the catalytic activity of single site Fe/SiO2 catalyst was lower than that of Zn/SiO2. Such result suggested heterolytic cleavage of C-H bonds was slow for transition metals, e.g., Co and Fe, due to their weak Lewis acidity, and it may mitigate the advantages gained in rapid β-hydride elimination. An exploration of ligand effects for improving heterolytic cleavage over single site heterogeneous catalysts was performed. The strength of metal oxygen bond governed by ligand electron donating effects and ligand basicity were found to be the critical chemical descriptors for a facile heterolytic cleavage. Those observed principles of ligand effects would lead to a new strategy of rational catalyst design for a superior dehydrogenation catalyst.
Ph.D. in Chemistry, December 2015
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Title: TEXT MESSAGE REMINDERS AND TREATMENT ADHERENCE IN A TYPE II DIABETES POPULATION: A FEASIBILITY STUDY
Creator: Kramer, Alexis J.
Date: 2014, 2014-05
Description: Type II Diabetes (T2DM) is a chronic disease effecting millions of people worldwide. It is well documented that lifestyle changes including...
Show moreType II Diabetes (T2DM) is a chronic disease effecting millions of people worldwide. It is well documented that lifestyle changes including adherence to treatment regimens (e.g. glucose monitoring) can be very effective in reducing the onset and progression of T2DM. The literature suggests that individuals within this population are often non-compliant with treatment recommendations, for a variety of reasons (e.g. psychological factors, availability of resources, co-morbid conditions). The purpose of this study was to investigate the suitability, recruitment and retention feasibility, and preliminary outcomes of a text message reminder system on treatment adherence within a type 2 diabetic population, as measured by blood glucose levels (HbA1c). A total of 28 participants were randomized into experimental or no-treatment conditions. Participants in the experimental group received text message reminders on either a fixed or variable schedule; with either neutral or calming test message content. They also completed a qualitative feedback measure, to assess participant satisfaction with the proposed intervention. Participants in the no-treatment condition did not receive any text message reminders. All participants completed the Diabetes Care Profile (DCP) and Short Form-36 Health Form Survey, Version 2 (SF-36v2) at baseline and three months later (time 2). Preliminary analyses show that frequency of text message reminder significantly impacted glucose levels over time. The content of the text message was not shown to have a significant effect on glucose levels. Participant perception of the proposed intervention was mixed. Despite diverse recruitment efforts, recruitment was low, however, retention was high.
PH.D in Psychology, May 2014
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Title: THE EFFECT OF NANOPARTICLE SELF-STRUCTURING ON WETTING AND SPREADING OF NANOFLUIDS ON SOLID SURFACES
Creator: Kondiparty, Kirtiprakash
Date: 2011-11, 2011-12
Description: Nanofluids are suspensions of nanometer-sized particles in liquids. The nanoparticles self-structure at the three-phase contact region...
Show moreNanofluids are suspensions of nanometer-sized particles in liquids. The nanoparticles self-structure at the three-phase contact region resulting in the structural disjoining pressure gradient which causes enhanced the spreading of nanofluids compared to simple fluids without nanoparticles. In this thesis, we attempt to understand the effect of the structural disjoining pressure on the spreading dynamics of nanofluids on solid surfaces. We observed nanoparticle self-structuring phenomena during film thinning on a smooth hydrophilic glass surface using a silica-nanoparticle aqueous suspension and reflected light interferometry. Our experiments revealed that film formed from small drop is thicker and contains more particle layers than a film formed from large drop. The data for the film-meniscus contact angle verses film thickness were obtained and used to calculate the structural energy isotherm of an asymmetric film. We studied the effect of structural disjoining pressure on the wedge meniscus profile formed by an oil drop on solid surface surrounded by nanofluid using Laplace Equation augmented with the structural disjoining pressure. Our analyses indicate that a suitable combination of the nanoparticle concentration, nanoparticle size, contact angle, and capillary pressure can result not only in the displacement of the three-phase contact line, but also in the spontaneous spreading of the nanofluid as a film on solid surface. We validated our theoretical predictions using experiments where we observed spreading of nanofluid on glass surface displacing a sessile drop of canola oil. The dynamic spreading of the nanofluid on a solid surface between a sessile oil drop on solid surface was experimentally measured using reflected light microscopy. We xiv obtained the rate of nanofluid spreading by plotting the position of the inner contact line with time. The nanofluid film was found to spread at a constant velocity. We modeled the spreading dynamics of the nanofluid film using the lubrication approximation of the Navier-Stokes Equation, taking into consideration the structural disjoining pressure in the over-all pressure balance. The model was evaluated by estimating the rate of nanofluid spreading for the 10v% nanofluid. The rate of spreading thus predicted by the dynamics model for 10v% nanofluid was in good agreement with the experimental observations.
Ph.D. in Chemical Engineering, December 2011
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Title: INVESTIGATING THE IMPACT OF EDUCATION AND CONTACT-BASED ANTI-STIGMA INTERVENTIONS ON THE STIGMA OF MENTAL ILLNESS IN THE COLLEGE POPULATION
Creator: Kosyluk, Kristin
Date: 2014, 2014-12
Description: Approximately one in four college students screen positive for a mental illness, however many who might benefit from mental health care do not...
Show moreApproximately one in four college students screen positive for a mental illness, however many who might benefit from mental health care do not seek treatment. Amongst both the general adult population and college students, stigma has been shown to be a predictor of treatment engagement, with higher levels of stigma with regard to mental illness predicting lower levels of treatment utilization. It has been demonstrated in the general adult population that contact-based anti-stigma programs are the most effective approach to stigma change, followed by education-based programs. This study aimed to investigate the impact of contact- and education-based anti-stigma interventions, relative to a control condition, on mental illness stigma, affirming attitudes towards individuals with mental illness, discrimination towards individuals with mental illness, and treatment seeking amongst college students. Both contact- and education-based interventions were found to have a significant impact on personal stigma, perceptions of empowerment, desired social distance from individuals with mental illness (a proxy of discrimination), attitudes towards treatment seeking, and intentions to seek treatment from formal sources of support. No difference in effect was demonstrated between the contact- and education-based conditions. These findings suggest that these two approaches may be equally effective for challenging stigma amongst college students.
Ph.D. in Psychology, December 2014
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Title: NEUROPATHOLOGIC CORRELATES OF BRAIN MACROSTRUCTURE
Creator: Kotrotsou, Aikaterini
Date: 2014, 2014-07
Description: Alzheimer’s disease, the most common form of dementia, is a degenerative disorder of the brain that leads to memory loss. Clinical diagnostic...
Show moreAlzheimer’s disease, the most common form of dementia, is a degenerative disorder of the brain that leads to memory loss. Clinical diagnostic techniques in use today rely on mental and behavioral tests and physical examinations and only provide diagnoses of possible or probable Alzheimer’s disease. However, lately it has become clear that clinical-pathological correspondence is not always consistent. A definitive diagnosis of Alzheimer’s disease is only possible via histology, when the density of neurofibrillary tangles and amyloid plaques is measured. Therefore, the development of a reliable neuroimaging technique that allows detection of Alzheimer’s pathology during life is needed. This method would be noninvasive, and could allow the detection of Alzheimer’s disease in the early stages, and could be also used to monitor the progression of the disease through time. The purpose of this work was to investigate the use of magnetic resonance imaging (MRI) as diagnostic tool for Alzheimer’s pathology and other age-related neurodegenerative pathologies that are common in older persons. To uncover the anatomical origins and determine the macrostructural signatures of age-related neuropathologies, it is necessary to link MRI findings with pathologic information on the same individuals. In this work, we focused on imaging cerebral hemispheres ex-vivo, when a complete pathology report was available from a board-certified neuropathologist. The main difference between this work and any other study is the abundance of postmortem imaging data paired with neuropathology data in a relatively large pool of subjects. First, we developed and validated a protocol to perform ex-vivo MR volumetry. By using this protocol we observed the longitudinal behavior of the volume of different brain regions. Furthermore, we tested the hypothesis that volumetric measurements performed ex-vivo are associated with in-vivo measurements. It was shown that: (a) regional brain volumes measured with this approach for ex-vivo MR volumetry remain relatively unchanged for a period of 6 months postmortem, and (b) a linear correspondence was detected between in-vivo and ex-vivo measurements, suggesting that this approach captures information linked to antemortem macrostructural brain characteristics. Using the approach for ex-vivo MR volumetry, we combined ex-vivo MR volumetry with pathology on the same adults. AD pathology was significantly negatively correlated with volumes of cortical gray matter regions, mainly in the temporal, frontal, parietal and cingulate cortices, subcortical gray matter, and whole-hemisphere white matter. A significant negative correlation was shown between hippocampal sclerosis and volumes of the hippocampus, as well as other temporal and frontal gray matter regions. Finally, we performed a morphometric MRI study to investigate associations of brain volumes with pathology using voxel-based analysis. This technique allows the assessment of gray and white matter volumes in subjects with different pathologies compared with controls in an automated fashion, across the whole brain. AD pathology was negatively associated with regions of gray matter and white matter located in temporal and frontal lobes, and orbitofrontal cortex. This work examined the associations of brain volumes with Alzheimer’s pathology and other typed of age-related neurodegenerative pathologies. Combining histological result with MR images requires that the time elapsed between imaging and histology is minimal. Ex-vivo MRI provides images at essentially the same time-point as histological examination of the tissue, and this study is unique in that it involves a large number of cadaveric brain hemispheres. The findings of this ex-vivo study could allow for future standardization of MRI as a biomarker of neurodegenerative diseases, and also allow in identification and classification of subjects in groups for tests of new drugs.
Ph.D. in Biomedical Engineering, July 2014
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Title: DEVELOPMENT OF ADVANCED PACKAGING, FABRICATION AND RELIABILITY METHODS FOR SUBMINIATURE IMPLANTABLE NEURAL PROSTHESES
Creator: Kim, Taehyung
Date: 2011-08, 2011-07
Description: The main purpose of the present thesis is to study the critical reliability issues of polymeric encapsulated electronic devices for visual...
Show moreThe main purpose of the present thesis is to study the critical reliability issues of polymeric encapsulated electronic devices for visual prosthesis. Visual prosthesis has been compatibly studied over twenty years in many professional research labs. The electric design of circuit for the visual prosthesis has been well studied so far. However, the device packaging design and reliability have been not studied extensively. In particular, failure analysis and reliability using non-hermetic packaging for long lifetime visual prosthesis have been poorly studied. The first step of the research for this thesis was to create a mechanical design of a visual prosthesis prototype. The prototype device was created by fabricate a multi-layer structure consisting of electrodes, substrate, and integrated circuit chip with silicone encapsulated packaging. The interconnection between the chip and electrodes used Au wire and Al bonding pad. The prototype devices were tested in a liquid water. This water environment is not a common reliability test for commercial electronic packaging. Relative humidity testing is a common and widely used testing methods, but the visual prosthesis device cannot be applied to gas phase relative humidity testing due to the environment condition. Water absorption in polymeric material in the liquid water is higher than in the vapor water. After water penetrated interconnection interface, the Au-Al intermetallic compound becomes oxidized and generates bonding die open failure. From these unusual testing results, we were conformed the failure mechanism and predicted the lifetime using Au-Al imtermetallic growth pattern and oxidation. Additional discussions include transition metal ions in CSF to expect the other failure mechanisms. Wafer and packaging level xiii failure mechanisms by Cu and Fe ions are also discussed in this thesis. The end of this thesis discuss possible fabrication processing to protect overall external environment effects for polymeric packaging visual prosthesis. Overall this thesis study, which uses polymeric packaging electronic devices for bio-implant research, concluded that devices may not make good reliability devices in the CSF environment. The corrosion, oxidation and metallization on or in metal surfaces and interconnection interfaces should continually be studied to produce longer lasting electronic devices over 30 years. The reliability of the visual prosthesis has not been well studied in any other professional research labs, so this thesis may give or address some initial guidelines to help save time for the project decision in the future to develop advanced hermetic packaging for bioimplantable electronic devices.
Ph.D. in Materials Science and Engineering, July 2011
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Title: BLADE PITCH OPTIMIZATION METHODS FOR VERTICAL-AXIS WIND TURBINES
Creator: Kozak, Peter
Date: 2016, 2016-07
Description: Vertical-axis wind turbines (VAWTs) offer an inherently simpler design than horizontal-axis machines, while their lower blade speed mitigates...
Show moreVertical-axis wind turbines (VAWTs) offer an inherently simpler design than horizontal-axis machines, while their lower blade speed mitigates safety and noise concerns, potentially allowing for installation closer to populated and ecologically sensitive areas. While VAWTs do offer significant operational advantages, develop- ment has been hampered by the difficulty of modeling the aerodynamics involved, further complicated by their rotating geometry. This thesis presents results from a simulation of a baseline VAWT computed using Star-CCM+, a commercial nite volume (FVM) code. VAWT aerodynamics are shown to be dominated at low tip- speed ratios by dynamic stall phenomena and at high tip-speed ratios by wake-blade interactions. Several optimization techniques have been developed for the adjustment of blade pitch based on finite-volume simulations and streamtube models. The effectiveness of the optimization procedure is evaluated and the basic architecture for a feedback control system is proposed. Implementation of variable blade pitch is shown to increase a baseline turbine's power output between 40%-100%, depending on the optimization technique, improving the turbine's competitiveness when compared with a commercially-available horizontal-axis turbine.
Ph.D. in Aerospace and Mechanical Engineering, July 2016
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Title: LIPID-LIPID AND LIPID-DRUG INTERACTIONS IN BIOLOGICAL MEMBRANES
Creator: Martynowycz, Michael W.
Date: 2016, 2016-07
Description: Interactions between lipids and drug molecules in biological membranes help govern proper biological function in organisms. The mechanisms...
Show moreInteractions between lipids and drug molecules in biological membranes help govern proper biological function in organisms. The mechanisms responsible for hydrophobic drug permeation remain elusive. Many small molecule drugs are hydrophobic. These drugs inhibit proteins in the cellular interior. The rise of antibiotic resistance in bacteria is thought to be caused by mutations in protein structure, changing drug kinetics to favor growth. However, small molecule drugs have been shown to have different mechanisms depending in the structure of the lipid membrane of the target cell. Biological membranes are investigated using Langmuir monolayers at the airliquid interface. These offer the highest level of control in the mimetic system and allow them to be investigated using complementary techniques. Langmuir isotherms and insertion assays are used to determine the area occupied by each lipid in the membrane and the change in area caused by the introduction of a drug molecule, respectively. Specular X-ray re ectivity is used to determine the electron density of the monolayer, and grazing incidence X-ray diffraction is used to determine the inplane order of the monolayer. These methods determine the affinity of the drug and the mechanism of action. Studies are presented on hydrophobic drugs with mammalian membrane mimics using warfarin along with modified analogues, called superwarfarins. Data shows that toxicity of these modified drugs are modulated by the membrane cholesterol content in cells; explaining several previously unexplained effects of the drugs. Membrane mimics of bacteria are investigated along with their interactions with a hydrophobic antibiotic, novobiocin. Data suggests that permeation of the drug is mediated by modifications to the membrane lipids, and completely ceases translocation under certain circumstances.
Ph.D. in Physics, July 2016
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Title: THE RELATIONSHIP BETWEEN ATTRIBUTIONAL STYLE, DEPRESSION, AND ACCEPTANCE OF DISABILITY IN CHINESE INDIVIDUALS WITH SPINAL CORD INJURY
Creator: Heyne, Mark Michael
Date: 2011-03-27, 2011-05
Description: The positive relationship between negative attributional style and depression has been established in both those with and without chronic...
Show moreThe positive relationship between negative attributional style and depression has been established in both those with and without chronic illness or physical disability; however, this relationship remains uncharacterized in those with spinal cord injury (SCI), which is surprising, given this condition’s significant potential for negative psychosocial implications. Although there is evidence that the association among these two variables generalizes across cultures and disabilities, other findings suggests that the Chinese have a more negative attributional style than their Western counterparts, which could alter the relationship between attributional style and depression among Chinese with SCI. Likewise, the construct of acceptance of disability (AD) and its correlates has been covered extensively in Western samples with SCI, but has received virtually no attention in Eastern samples. The present study examined these variables within the context of SCI in a Chinese sample. Participants were 158 Chinese individuals with SCI who completed a battery of self-report measures of demographic, injury-related, and psychosocial variables. Cluster analysis results suggested three distinct clusters based on attributional style (positive, neutral, negative). Those in the positive attributional style cluster were more likely to have tetraplegia than paraplegia, but exhibited less functional disability and depressive symptoms, and higher AD than the negative cluster. Path analysis indicated that higher functional disability predicted both more negative attributional style and higher depressive symptomology; attributional style did not directly predict depression, in contrast to findings from previous studies. Higher depressive symptomology was found to predict lower AD, consistent with existing research.
Ph.D. in Psychology, May 2011
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Title: SELF-HEALING IN MICROGRID OPERATION AND MESSAGE-PASSING BASED DEMAND RESPONSE
Creator: Barati, Masoud
Date: 2013, 2013-12
Description: Electrical energy can be more efficiently and reliably generated, transmitted, and consumed over electricity grids as smart grids evolve....
Show moreElectrical energy can be more efficiently and reliably generated, transmitted, and consumed over electricity grids as smart grids evolve. Through the two-way flow of information between suppliers and consumers, the grids can encourage and adapt more easily to the increased consumer participation in energy management through demand response. This dissertation studies the transactive energy management on the residential side via microgrid operation and message-passing based demand response. A microgrid is an independent section of the electrical distribution grid with capabilities to transmit, produce, and distribute power within a localized area. The implementation of the microgrid increases the reliability and quality of power supply through various means including the self-healing paradigm. A microgrid operating under a self-healing paradigm can automatically and intelligently detect and reroute the power flow around an unexpected line fault. This dissertation presents the formulations and the methodologies of the self-healing process, which is incorporated into the microgrid operation for real-time scheduling. The self-healing process tries to find the best topology of the microgrid including radial and closed-loop configurations that minimize the total operation cost while respecting all security constraints. The dissertation also considers the AC solution of optimal power flow for self-healing applications, which enhances the reactive power flow for mitigating any bus voltage violations and for alleviating any real and reactive loop flows. The message-passing based demand response scheme relies on dynamic pricing of electricity to regulate electricity consumption. To achieve this goal, load serving entities via messages-passing gather the information such as consumers’ usage of electricity from xv ii smart meters, and set the dynamic price level appropriately in order to reduce the peak electricity demand through the cooperation of customers. In response to the dynamic price signals, customers can shift their demands automatically, with the help of a home energy management system, or manually to the off-peak hours so as to minimize their electricity payment and maximize its utility function. The message-passing based demand response scheme is applied in this dissertation to residential household scheduling, which is a key component of a future smart grid that can help reduce peak loads and adjust elastic demands to provide economic and emergency demand responses. A decentralized and iterative message-passing method is developed for solving the residential household scheduling problem. Under the context of a competitive retail electricity market, this dissertation analytically models load serving entities’ production function based on wellknown economic theory, analytically models household behaviors based on the ordinal and cardinal concepts of the utility function and using a static game strategy, and efficiently calculates retail electricity price with pure ex-ante or combinatorial pricing strategies. A simple yet effective price stabilization strategy for retail electricity price is proposed to mitigate the potential price and consumption spike caused by uncertainties in wholesale electricity prices.
PH.D in Electrical Engineering, July 2013
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Title: THE PATH TO HIGH Q-FACTORS IN SUPERCONDUCTING ACCELERATING CAVITIES: FLUX EXPULSION AND SURFACE RESISTANCE OPTIMIZATION
Creator: Martinello, Martina
Date: 2016, 2016-12
Description: Accelerating cavities are devices resonating in the radio-frequency (RF) range used to accelerate charged particles in accelerators....
Show moreAccelerating cavities are devices resonating in the radio-frequency (RF) range used to accelerate charged particles in accelerators. Superconducting accelerating cavities are made out of niobium and operate at the liquid helium temperature. Even if superconducting, these resonating structures have some RF driven surface resistance that causes power dissipation. In order to decrease as much as possible the power losses, the cavity quality factor must be increased by decreasing the surface resistance. In this dissertation, the RF surface resistance is analyzed for a large variety of cavities made with different state-of-the-art surface treatments, with the goal of finding the surface treatment capable to return the highest Q-factor values in a cryomodule-like environment. This study analyzes not only the superconducting properties described by the BCS surface resistance, which is the contribution that takes into account dissipation due to quasi-particle excitations, but also the increasing of the surface resistance due to trapped flux. When cavities are cooled down below their critical temperature inside a cryomodule, there is always some remnant magnetic field that may be trapped increasing the global RF surface resistance. This thesis also analyzes how the fraction of external magnetic field, which is actually trapped in the cavity during the cooldown, can be minimized. This study is performed on an elliptical single-cell horizontally cooled cavity, resembling the geometry of cavities cooled in accelerator cryomodules. The horizontal cooldown study reveals that, as in case of the vertical cooldown, when the cooling is performed fast, large thermal gradients are created along the cavity helping magnetic flux expulsion. However, for this geometry the complete magnetic flux expulsion from the cavity equator is more difficult to achieve. This becomes even more challenging in presence of orthogonal magnetic field, that is easily trapped on top of the cavity equator causing temperature rising. The physics behind the magnetic flux expulsion is also analyzed, showing that during a fast cooldown the magnetic field structures, called vortices, tend to move in the same direction of the thermal gradient, from the Meissner state region to the mixed state region, minimizing the Gibbs free energy. On the other hand, during a slow cool down, not only the vortices movement is limited by the absence of thermal gradients, but, also, at the end of the superconducting transition, the magnetic field concentrates along randomly distributed normal-conducting region from which it cannot be expelled anymore. The systematic study of the surface resistance components performed for the different surface treatments, reveals that the BCS surface resistance and the trapped flux surface resistance have opposite trends as a function of the surface impurity content, defined by the mean free path. At medium field value, the BCS surface resistance is minimized for nitrogen-doped cavities and significantly larger for standard niobium cavities. On the other hand, Nitrogen-doped cavities show larger dissipation due to trapped flux. This is consequence of the bell-shaped trend of the trapped flux sensitivity as a function of the mean free path. Such experimental findings allow also a better understanding of the RF dissipation due to trapped flux. The best compromise between all the surface resistance components, taking into account the possibility of trapping some external magnetic field, is given by light nitrogen-doping treatments. However, the beneficial effects of the nitrogen-doping is completely lost when large amount of magnetic field is trapped during the cooldown, underlying the importance of both cooldown and magnetic field shielding optimization in high quality factors cryomodules.
Ph.D. in Physics, December 2016
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Title: NETWORK-LEVEL VEHICLE CRASH PREDICTIONS INCORPORATING TIME-DEPENDENT EFFECTS INTO CONSIDERATIONS
Creator: Dao, Hoang
Date: 2016, 2016-07
Description: Maintaining highway safety is viewed as the over-arching goal of mananging transportation systems at all levels. According to the National...
Show moreMaintaining highway safety is viewed as the over-arching goal of mananging transportation systems at all levels. According to the National Highway Traffic Safety Administration (NHTSA), over 37,000 people got killed and 2.35 million are injured in road crashes annually. The equivalent economic and societal losses are on the order of over $231 billion, or an average of $820 per person. Thus, developing vehicle crash models that can accurately predict crash occurrences becomes essential. The study begins with literature review of models for predicting vehicle crash frequencies and crash severity levels on highway segments and at highway intersections. The findings of literature review indicate that some models lack prediction accuracy owing to exclusion of many crashing contributing factors. Consequently, a new methodology for improved vehicle crash predictability is proposed to include as many crash contributing factors as possible. In addition, the proposed methodology aims to conduct crash predictions targeting a highway network. Two computational experiments are performed for methodology application, including one on highway segment-related crash predictions using data on Highway Safety Information System for Illinois from 2001 to 2010, and another one on intersection-related crash predictions using crash data on more than one thousand intersections for period 2004 to 2010 provided by city of Chicago. Cross comparisons are made on the results obtained by applying the proposed methodology, method documented in Highway Safety Manual (AASHTO, 2010), and Empirical Bayesian (EB) before-after method for validation. The proposed methodology is found to have out-performed the other two methods. Future research directions are provided for continuing refinements of the proposed methodology.
Ph.D. in Civil Engineering, July 2016
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Title: THE ROLE OF EXPERIENTIAL AVOIDANCE IN THE ASSOCIATION BETWEEN ANXIETY SENSITIVITY AND EMOTIONAL EATING IN NON-EATING DISORDERED OVERWEIGHT/OBESE INDIVIDUALS SEEKING WEIGHT LOSS TREATMENT BY
Creator: Dave, Pooja N.
Date: 2015, 2015-12
Description: Obesity is one of the most rapidly emerging public health concerns whose prevalence far exceeds that of eating disorders (Hudson et al., 2007)...
Show moreObesity is one of the most rapidly emerging public health concerns whose prevalence far exceeds that of eating disorders (Hudson et al., 2007). As most obese individuals do not meet criteria for an eating disorder, emotional eating (EE) may be a more useful construct in understanding obesity more broadly. Anxiety sensitivity (AS) has been recognized as a transdiagnostic risk factor for a variety of problem behaviors including EE in obese individuals (Hearon et al., 2012). In addition, recent research has highlighted the mediating role of maladaptive responses to internal experiences in the association between AS and eating pathology (Anestis et al., 2008). Experiential avoidance (EA) is one such maladaptive response that has garnered attention for predicting maladaptive coping for a range of psychiatric conditions. To date, only one study has examined the relationship between AS and EE in obese individuals (Hearon et al., 2012). This study aims to replicate and extend their findings by examining the role of EA in this relationship. A sample of 127 obese patients without an eating disorder seeking weight-loss treatment completed questionnaires to assess emotional eating, experiential avoidance, and anxiety sensitivity. When controlling for gender, negative affect, and current psychiatric diagnosis and treatment, EA was found to fully mediate the relationship between AS and EE. There was a significant positive indirect effect (B = .285, CI95% = .155-.462) and a non-significant direct effect (B = .039, p = .786. These findings provide initial support for the mediating role of EA in the association between AS and EE in an obese, non-eating disordered, weight-loss treatment-seeking sample.Further, the identification of AS and EA as relevant in the development of emotional eating adds to the growing literature base arguing for the conceptualization of these two factors as transdiagnostic risk factors for a wide range of problem behaviors, including emotional eating. Clinical and research implications are discussed, as well as strengths and limitations of the study. Recommendations for the development of interventions targeting individuals high in anxiety sensitivity, with the intention of reducing experiential avoidance, are also reviewed.Further, the identification of AS and EA as relevant in the development of emotional eating adds to the growing literature base arguing for the conceptualization of these two factors as transdiagnostic risk factors for a wide range of problem behaviors, including emotional eating. Clinical and research implications are discussed, as well as strengths and limitations of the study. Recommendations for the development of interventions targeting individuals high in anxiety sensitivity, with the intention of reducing experiential avoidance, are also reviewed.
Ph.D. in Psychology, December 2015
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Title: ELECTRIC VEHICLE (EV) STORAGE SUPPLY CHAIN RISK AND THE ENERGY MARKET: A MICRO AND MACROECONOMIC RISK MANAGEMENT APPROACH
Creator: Aguilar, Susanna D.
Date: 2015, 2015-12
Description: NO ABSTRACT
Ph.D. in Management Science, December 2015

Title: POSTMORTEM MRI OF THE ELDERLY HUMAN BRAIN: METHODS AND APPLICATIONS TO HISTOPATHOLOGICALLY VERIFIED ALZHEIMER’S DISEASE AND OTHER NEUROPATHOLOGIES OF AGING
Creator: Dawe, Robert J.
Date: 2011-04-08, 2011-05
Description: Currently, a definitive diagnosis of Alzheimer’s disease is only possible postmortem, when the distribution and type of pathology in the brain...
Show moreCurrently, a definitive diagnosis of Alzheimer’s disease is only possible postmortem, when the distribution and type of pathology in the brain can be directly verified via histology. Clinical diagnostic techniques in use today rely on behavioral and neuropsychological criteria and only provide diagnoses of possible or probable Alzheimer’s disease, both of which indicate that significant irreversible neuronal damage has already occurred. Therefore, a neuroimaging technique for detection of Alzheimer’s pathology during life is highly sought after. Such a technique would be noninvasive, could provide a quantitative evaluation of potential therapies in patients, and could eventually be used for early detection of Alzheimer’s disease. The purpose of this work was to investigate the use of magnetic resonance imaging (MRI) as diagnostic tool for Alzheimer’s and other types of pathology that are common in the elderly human brain. In order to correlate imaging data with a diagnosis of neuropathology that was guaranteed to be accurate, we focused on imaging cerebral hemispheres postmortem (ex vivo), when a complete pathology report was available from a board-certified neuropathologist. The main difference between this work and any other study is the abundance of postmortem imaging data paired with neuropathology data in a relatively large pool of subjects. First, we examined the relation between postmortem hippocampal volume, measured from MR images, and pathological diagnosis of Alzheimer’s and other common types of pathology. It was shown that Alzheimer’s, along with hippocampal sclerosis, are associated with a dramatic reduction in hippocampal volume. Furthermore, the pattern of hippocampal atrophy differs between these two types of neuropathology, which may provide a means of distinguishing one from the other in vivo using MR images. Next, the transverse relation time constant, T2, was examined over time in five postmortem hemispheres that were undergoing chemical fixation via immersion in formaldehyde solution. This investigation yielded two important pieces of information: (a) for the purposes of obtaining stable measurements of T2, the ideal time to conduct postmortem MRI of the human brain is at least one month postmortem, and (b) correction of T2 measurements for the postmortem interval to imaging is both possible and necessary for analysis of T2 alterations associated with pathology. Using the information gleaned from the study of changes in transverse relaxation over time, we next examined the dependence of T2 on the presence of Alzheimer’s pathology. Significant prolongation of T2 was demonstrated in various white matter regions in cases of Alzheimer’s, suggesting degeneration of that tissue. Significant shortening of T2 was detected in the basal ganglia, suggesting that accumulation of iron in that region is associated with the progression of Alzheimer’s disease. Finally, a method of conducting high quality diffusion tensor MRI of postmortem cerebral hemispheres was developed. Compared to in vivo diffusion tensor MRI, the postmortem variant of the technique is much more challenging, since the signal to noise ratio is affected very negatively by a combination of faster transverse relaxation, reduced water diffusivity, and the resulting need for longer diffusion-sensitizing gradients. To a large extent, these problems have been solved, and we have now implemented a protocol for routine diffusion tensor MRI of recently deceased human brains which takes less than one hour of scan time. This work examined three MRI techniques that hold great promise in their ability to detect Alzheimer’s and other types of neuropathology: hippocampal volumetry, mapping of the transverse relaxation time constant T2, and diffusion tensor imaging. The fact that all three techniques were carried out postmortem is an important contribution, since it allows for imaging results to be correlated with a complete and accurate pathological diagnosis of disease. Findings from postmortem studies could one day be translated to the in vivo case, where they can potentially be used for antemortem diagnosis of Alzheimer’s disease.
Ph.D. in Biomedical Engineering, May 2011
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Title: PHOTOCATHODE TUNABILITY: THE PHOTOEMISSIVE PROPERTIES OF ULTRA-THIN MULTILAYERED MgO/Ag/MgO FILMS SYNTHESIZED BY PULSED LASER DEPOSITION
Creator: Velazquez, Daniel Gomez
Date: 2015, 2015-05
Description: Much of the early development of photocathode materials was aimed at the growth of photoemissive thin films with low work function, and high...
Show moreMuch of the early development of photocathode materials was aimed at the growth of photoemissive thin films with low work function, and high quantum efficiency (QE). It has been shown, both theoretically and experimentally, that metal-insulator junctions can lead to the modification of the work function and QE for coverages of a few monolayers of metal oxides on metallic substrates. However, the production of electron beams suitable for new photoinjector technologies in many instances requires low emittance beams from the cathode itself. Often the cathode intrinsic emittance plays an important role in new e-gun designs. A demonstration of the ability to control photoemissive properties by engineering the band structure of a photocathode could provide a pathway to meet the demands of new photoinjector technologies. Nemeth et al. [Phys. Rev. Lett. 104, 046801 (2010)] used density functional theory (DFT) to model the properties of a multilayered structure of MgO/Ag(001)/MgO with 4 monolayers of Ag(001) flanked by n monolayers (ML) of MgO. Their model indicated that it is possible to reduce the emittance of a photoemitted electron beam when the thickness n of the MgO layers is 2 or 3 monolayers because the surface band structure exhibits a narrowing of the density of occupied states in momentum near the Γ-point neighboring the Fermi Level. The theoretical prediction concerning the emission properties of these multilayers structures was tested by fabricating them, and then characterizing their emission properties. Synthesis of multilayered MgO/Ag/MgO films was performed using a custom-built pulsed laser deposition (PLD) system. In-situ growth monitoring was carried out by Reflection High-Energy Electron Diffraction (RHEED). Ex-situ techniques such as Scanning Tunneling Microscopy (STM), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (EDS) and Photoelectron Spectroscopy (PES) were used to show the formation of the crystalline and chemical structure of the multilayered films. A Kelvin Probe/photocurrent-detector system, custom-built for this research, was used to measure the work function and QE of the samples. Angle Resolved Photoelectron Spectroscopy was used to measure the angular photoelectron yield. Simultaneous reduction of work function and increase of QE was observed for (001) oriented multilayers of various thicknesses with respect to that of a bare Ag/MgO(001) surface. Work function measurements of multilayers of various thicknesses in the (111) orientation also registered a monotonic reduction with respect to that of a bare Ag/Si(111) surface. Angular emission was compared for a MgO/Ag/MgO multilayer (thicknesses of 3 ML/4 ML/3 ML) sample and Ag/MgO(001). Emission analysis of the angle-resolved photoelectron spectra shows a net change in the angular emission with high kinetic energy electron density shifted toward surface-normal emission. Experimental results were consistent with theoretical predictions, which open the promising possibility of customizing emission properties by direct manipulation of the surface band structure of the emitter.
Ph.D. in Physics, May 2015
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Title: INTEGRATION OF DAYLIGHT IN THE COMMERCIALLY USED BUILDINGS FOR ENERGY SAVING PURPOSES
Creator: Tabibzadeh, Meysam
Date: 2014, 2014-07
Description: The integration between different building systems’ operation in response to various room and weather conditions has a direct positive effect...
Show moreThe integration between different building systems’ operation in response to various room and weather conditions has a direct positive effect on buildings energy performance and cost effectiveness. A Building Automation System (BAS) or an integrated Building Energy Management System (BEMS) typically control five major building systems, including people occupancy detection, shading control, HVAC, and lighting systems. Other building systems and internal energy loads also need to be considered when developing integrated controls and energy efficiency in office buildings. The controls are designed to operate in different building zones (lighting and thermal), while communicating with the main building management system. Whether the zone is being occupied or not will define further actions by other control components. The main goal of this research is to improve energy performance in commercial office buildings by developing the integration between various building controls and the use of natural light indoors and outside views while maintaining both the occupants’ visual and thermal comfort and high building energy performance at the same time. In this research, the proposed synchronization between building occupancy, daylighting, and integrated controls for various building systems in a commercial office space was assessed using computer simulations. The study uses Microsoft Excel as the primary database and result compiling platform. The work flow algorithm of the integrated control (in Visual Basic Application for Excel) automatically defines the new simulation criteria, makes adjustments in the simulation inputs, and runs DOE2.2 energy simulations for the proposed models with integrated controls as well as the baseline model (compliant with the ASHRAE 90.1-2010 standard) for further analysis. The simulations are conducted for eight simulation dates over five years. The results from the proposed model are analyzed and compared with the baseline results in order to evaluate its energy performance and to determine possible savings. The simulation results analysis determines how the implementation of the proposed system can improve the daylighting and energy performance in the building by maximizing the integration between different building systems controls in response to different parameters, such as occupancy, weather conditions, and daylight. The evaluated results of the proposed system are summarized as the system and sub-system algorithms, features, and components of each system, and, finally, as the design guidelines for implementation of the new fully integrated controls for commercial office buildings. From the evaluation of the proposed system performance, the list of research outcomes and deliverables will be concluded, by determining the impact of integrated controls on the overall energy performance of the office work space. The fact that if and when the energy efficiency and improved comfort and environmental quality work hand in hand, in addition to and the role of integrated occupancy in improving the energy efficiency will define the level of success for the proposed control system. The final research outcome is the development of the integrated workflow that can be used in new Building Automation Systems (BAS) or incorporated into the simulation engine for “Simulation Assisted” (see section 2.2.2) Building Energy Management Systems (BEMS).
Ph.D. in Architecture, July 2014
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Title: PREDICTING COMMENT QUALITY ON NEWS WEBSITES: LINGUISTIC INDICATORS AND VIEWS FROM JOURNALISM PROFESSIONALS
Creator: Scott, Edward Blake
Date: 2014, 2014-07
Description: As the web has become more interactive in recent years, with website users having the ability to generate their own content, there has been...
Show moreAs the web has become more interactive in recent years, with website users having the ability to generate their own content, there has been increased tension between the content generated by users and the content generated by “professionals,” especially professional journalists and publishers. Many journalism professionals see the value of allowing users to comment on their work; for example, an interactive site that allows user commenting may increase users’ loyalty to the site, meaning they will return often, generate page views, and increase advertising revenue. Users can also serve to further explore an issue discussed in an article by broadening the discussion to include the viewpoints of those who aren’t professional journalists. However, publishers of news site comments have noted many problems with introducing user-generated content (UGC) to their sites, including the fact that users sometimes post inflammatory, insensitive, or lowquality comments that do not serve to improve the experience of the average reader. The problems caused by these kinds of comments have increased the amount of time and money required to moderate the comments section. Beyond inflammatory comments, however, is the problem of highlighting very good or high-quality comments. What is the degree to which those high-quality comments can be discovered through an automated process? This dissertation sought to test the extent to which comments to news sites can be automatically evaluated for quality by using a text-analysis system. Journalists were interviewed to get their views on user comments in general and comment quality in particular. The data from these interviews was used to generate hypotheses about which linguistic metrics provided by Coh-Metrix, a web-based text-analysis system, might be xiii most indicative of comment quality as described by journalists. Finally, a content analysis and close reading of a sample of news site comments was conducted in order to describe news site comments as a writing genre. Results from the interviews indicated that comment length, comment syntax, comment cohesion, comment narrativity, and comment individuality were all indicative of comment quality. However, statistical analyses on a sample of 246 comments failed to produce significant results for linguistic metrics hypothesized to be indicative of quality. Alternatively, an “positive engagement score” scale was created and used to identify how “engaging” comments were; this scale showed to have a significant, though minor, positive relationship with the number of recommendations a comment received from readers. Finally, the genre analysis of the sample of news site comments revealed that comments in the sample share a communicative purpose of providing additional content related to the article under discussion, providing a practical value for journalists and other professionals by offering tips and fact-checking functions, and providing a space where readers can debate the article in question and begin to develop a sense of community.
Ph.D. in Technical Communication, July 2014
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Title: OPTIMAL ROUTING ALGORITHMS IN ENERGY-HARVESTING WIRELESS SENSOR NETWORKS
Creator: Martinez, Gina
Date: 2014, 2014-12
Description: Harnessing energy from environmental sources such as solar and wind is an attractive solution to the critical energy limitation problem in...
Show moreHarnessing energy from environmental sources such as solar and wind is an attractive solution to the critical energy limitation problem in wireless sensor networks. Energy harvesting can potentially provide the network with perpetual and sustainable operation, or it can prolong network lifetime even for high consumption applications so as to justify the high cost of deployment. However, in order to efficiently utilize harvested energy, the energy source dynamics need to be incorporated into the network design. One way to do so is to make the network layer routing algorithm energy-harvest-aware. One common property of environmental energy sources is that they are generally only intermittently available. To address this, a storage unit such as a rechargeable battery can be introduced into the system. However, this is only a partial solution due to finite buffer storage capacities that cause harvested energy to be wasted when full. In this work, we aim to maximize the network lifetime by optimizing the energy availability and consumption alignment. To realize this objective, we first show that the minimization of energy wastage is a necessary condition to the maximization of available network energy. We then propose an on-demand routing algorithm that maximizes the total residual network energy by minimizing the energy consumption and wastage. Next, we illustrate the tradeoff between the two objectives of maximizing the total network energy and maximizing the minimum network energy in prolonging network lifetime. Then, we propose a linear-programming routing solution that maximizes a utility objective function based on this tradeoff. Although these routing approaches are shown to achieve high energy utilization, they are still based on deterministic harvest and consumption models. In the last part of this work, we propose a routing algorithm by applying the Semi-Markov Decision Process. Using this method, we are able to incorporate a comprehensive consideration of stochastic solar availability and traffic models, heterogeneous network properties such as non-uniform energy buffer capacities and consumption rates, and the optimization of an analytical formulation for network lifetime.
Ph.D. in Electrical and Computer Engineering, December 2014
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Title: DESIGN AND OPTIMIZATION OF CONFIGURABLE PASSIVE COMPONENTS FOR CMOS MILLIMETER-WAVE INTEGRATED CIRCUITS
Creator: Liu, Gui
Date: 2011-05-10, 2011-05
Description: With the rapid growth of wireless communications, there is an increasing demand for low cost, low power consumption, high data rates and high...
Show moreWith the rapid growth of wireless communications, there is an increasing demand for low cost, low power consumption, high data rates and high density integrated circuits. The continuous scaling of CMOS technologies promises to achieve higher frequencies of operation in the millimeter-wave (mm-wave) frequency regime. To enable lager bandwidth for higher data rates wireless applications, many efforts have been focused on the design of mm-wave CMOS integrated circuits. The emerging mm-wave wireless commercial applications such as Wireless Hi-definition Video (60 GHz), automotive radar (77 GHz) and mm-wave imaging system (94 GHz) have brought new challenges in devices technology and systems. There is an ever increasing demand for multi-band and multi-mode integrated wireless communication systems which have the advantages of power and area savings. Therefore, flexible and configurable mm-wave on-chip components and circuits are needed to accommodate a wide variety of wireless communication standards. On the other hand, the first silicon success of the challenging mm-wave integrated circuits requires superior and robust design capabilities in cutting-edge technologies. To satisfy customers by providing them with the fastest time-to-market and the lowest total cost, the configurable multiband mm-wave solution is preferred. Design of on-chip passive components operating at millimeter wave frequencies presents several challenges due to the ohmic loss, parasitic inductance and capacitance. Therefore, it requires both an accurate model and electromagnetic (EM) simulation tools to characterize the passive components. The other challenge of design of mm-wave on-chip passives is process variations which can have a significant effect on the robustness of the passive components and circuits. Methodology to compensate and adjust for process variations is needed. Passives that can be configured after fabrication would be an attractive way to obtain accurate parameters and overcome effects of process variations. The configurable Multilayer Coplanar Waveguide (MCPW) based transmission lines offer convenient method to alleviate the problem of process variations and obtain accurate inductor values. This dissertation focuses on the design of mm-wave passive components and their applications. Model, EM simulation, and optimization of several novel MCPW-based configurable inductors are presented. A 77-GHz voltage controlled oscillator (VCO) and a 77-GHz receiver employing the configurable inductors have been realized. The 77-GHz VCO with MCPW-based configurable inductor exhibits low phase noise and wide frequency tuning range. The 77-GHz receiver achieves low power and state-of-the-art performance. The successful implementations of several individual configurable passive components, a 77-GHz VCO, and a 77-GHz receiver demonstrate the feasibility to achieve good performance and robust design with configurable passive components.
Ph.D. in Electrical Engineering, May 2011
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