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Title: GRAIN BOUNDARY ENGINEERING OF POWDER-PROCESSED NI-BASE SUPERALLOY RR1000
Creator: Detrois, Martin
Date: 2016, 2016-05
Description: Grain boundary engineering (GBE) has been used to improve the properties of various polycrystalline materials by optimization of their grain...
Show moreGrain boundary engineering (GBE) has been used to improve the properties of various polycrystalline materials by optimization of their grain boundary network. Traditional processing routes for GBE often require multiple iterations of cold work followed by short annealing cycles where each iteration imparts a modest increase in the fraction of special grain boundaries. Multiple iterations are then required to achieve sufficiently high fractions (>50%) that result in the improved properties. Thus, this GBE approach is not suitable for the fabrication of large, complex-shaped structures and leads to added manufacturing lead time and cost. In this investigation, the Ni-base superalloy RR1000 used as turbine discs in gas turbine engines manufactured by Rolls-Royce, was considered for GBE using alternative processing routes more suitable to the forging of Ni-base superalloy components. A preliminary study of the e↵ects of hot deformation parameters closer to typical industrial processing revealed that the length fraction of ⌃3 boundaries increased from 35% to 52% following a single deformation/anneal cycle. Deformation parameters that resulted in strain accommodation via superplastic flow did not enhance the formation of ⌃3 boundaries upon annealing. Whereas deformation parameters that resulted in a dominant dislocation-based plasticity flow mechanism promoted the formation of annealing twins. Using misorientation maps and by estimating the stored strain energy from deformation, equations for the length fraction and density of ⌃3 boundaries were generated for high-temperature GBE of RR1000. The grain boundary characters obtained via high-temperature deformation, however, are less ideal than those resulting from traditional cold rolling. The underlying mechanisms responsible for the formation of ⌃3n boundaries during high-temperature GBE were further investigated. A larger starting grain size prior to deformation was found to be unfavorable to the formation of twin boundaries from twin-reorientation and annihilation of preexisting twins. While recrystallization was found to populate the microstructure with grains that contained very few twin boundaries, post-deformation texture was found to promote the formation of ⌃3 boundaries and triple junctions when Goss texture was present. A final consideration of larger scale forgings was used to raise an outlook on the current issues and the potential of high-temperature GBE for turbine engines.
Ph.D. in Materials Science and Engineering, May 2016
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Title: PERSONALITY SCALE CONSTRUCTION USING LATENT SEMANTIC ANALYSIS AS AN ITEM ANALYSIS METHODOLOGY
Creator: Pollak, Pamela Elizabeth
Date: 2012-05-07, 2012-05
Description: Linguistics has played an integral role throughout the history of personality scale development. The lexical hypothesis, which implies that by...
Show moreLinguistics has played an integral role throughout the history of personality scale development. The lexical hypothesis, which implies that by analyzing natural language personality will be understood because all personality is described in language, is the basis for personality scale construction. Despite the important role that language plays in describing personality, psychometric practice has traditionally focused on data analysis, rather than quantitative linguistic analysis when constructing personality scales. This study used a relatively new quantitative linguistics technique, Latent Semantic Analysis (LSA), to construct personality scales. Using an archival sample of N=501 with over n>1000 items, personality scales were constructed to measure aspects of the 16PF Questionnaire and the Big Five model. Scales created using traditional approaches were compared to scales created using LSA in terms of internal consistency reliability, construct validity and convergent validity, predicting five behavioral clusters of self-reported behaviors (e.g., drug-use, undependability, friendliness, creativity and erudition). Results from this study revealed that compared to scales created using a traditional approach, scales constructed using LSA had lower reliabilities, but mostly similar patterns of convergent validity and evidence of substantial construct validity.
Ph.D. in Psychology, May 2012
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Title: GUARANTEED ADAPTIVE UNIVARIATE FUNCTION APPROXIMATION
Creator: Ding, Yuhan
Date: 2015, 2015-12
Description: Numerical algorithms for univariate function approximation attempt to provide approximate solutions that differ from the original function by...
Show moreNumerical algorithms for univariate function approximation attempt to provide approximate solutions that differ from the original function by no more than a user-specified error tolerance. The computational cost is often determined adaptively by the algorithm based on the function values sampled. While adaptive algorithms are widely used in practice, most lack guarantees, i.e., conditions on input functions that ensure the error tolerance is met. In this dissertation we establish guaranteed adaptive numerical algorithms for univariate function approximation using piecewise linear splines. We introduce a guaranteed globally adaptive algorithm, funappxglobal g, in Chapter 2, along with sufficient conditions for the success of funappxglobal g. Two-sided bounds on the computational cost are given in Theorem 1. These bounds are of the same order as the computational cost for an algorithm that knows the infinity norm of the second derivative of the input function as a priori. Lower bound on the complexity of the problem is also provided in Theorem 3. To illustrate the advantages of funappxglobal g, corresponding numerical experiments are presented in Section 2.7. The cost of a globally adaptive algorithm is determined by the most peaky part of the input function. In contrast, locally adaptive algorithms sample more points where the function is peaky and fewer points elsewhere. In Chapter 3, we establish a locally adaptive algorithm, funappx g, with sufficient conditions for its success. An upper bound on the computational cost is also given in Theorem 4. One GUI example is presented to show how funappx g works. Some interesting function approximation problems in computational graphics are also presented. The key to analyzing these adaptive algorithms is looking at the error for cones of input functions rather than balls of input functions. Non-convex cones provide a setting where adaption may be beneficial.
Ph.D. in Applied Mathematics, December 2015
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Title: A BAYESIAN UPDATING APPROACH IN STRUCTURAL HEALTH MONITORING FOR DAMAGE DETECTION AND ASSESSMENT
Creator: Dirbaz, Mojtaba
Date: 2013, 2013-05
Description: The primary goal of Bridge Condition Assessment (BCA) is to determine the condition of a bridge to prevent any catastrophic failure as well as...
Show moreThe primary goal of Bridge Condition Assessment (BCA) is to determine the condition of a bridge to prevent any catastrophic failure as well as to enhance the structure’s safety and serviceability. The structural health and condition of in-service bridges is generally assessed through visual inspections and nondestructive testing and evaluation (NDT/NDE) methods conducted on a pre-set schedule. However, the ratings obtained from current visual inspections on a bridge are subjective, and do not include the uncertainty inherent in the results. Moreover, the condition ratings are often based on independent inspections and do not take into account the dependence of results on previous conditions of a bridge and prior condition ratings compiled for it. Furthermore, there is also a certain level of uncertainty involved in relating subjective ratings to the actual condition of the bridge. This study is aimed at conducting a research on damage detection of existing bridges utilizing available information on their structural conditions. The first part of the research focuses on a new method for assessing the condition of a bridge based on subjective ratings obtained for the bridge. This method will hereafter be referred to as Bayesian Bridge Condition Assessment (BBCA). BBCA consists of three parts: (1) identification of condition states for structural components, (2) determination of a Damage Index (DI), a parameter to describe the extent of damage to a structural component, and (3) determination of an Updated Damage Index (UDI) using Bayesian updating approach. UDI offers an enhanced measure that incorporates not only the relation between subjective rating and the structure’s health condition, but also the significance of new information as it becomes available. The basic assumptions and x general formulations of the Bayesian updating method is presented. Numerical illustrations are provided to demonstrate the applicability of the method to highway bridges. It is shown that the method described in this study is especially applicable to bridges for which visual inspection data are compiled on a periodic basis. One of the methodologies for damage detection and assessment is to use sensor data for identifying the modal characteristics of the structure. The second part of this research focuses on improving upon damage detection methods using sensor and/or modal data. Thus a new method for damage detection and assessment of structures using finite element analysis, and modal data is developed and demonstrated. This method will hereafter be referred to as Bayesian Structural Condition Assessment (BSCA). Using this method, (1) a Finite Element (FE) design model of the structure (undamaged) is constructed; (2) the measured modal data is updated using a Bayesian framework; and (3) the FE model of existing structure (with possibility of damage) is obtained using updated modal data based on an iterative optimization method that is used in estimating the stiffness of the damaged structure. Using these steps, the location and extent of any possible damage is then determined based on the difference between a structural element stiffness for the “as built condition” and “damaged condition.” Several numerical illustrations are presented to demonstrate the capability of the method to detect the location and extent of the damage. This method has been applied to a structural health monitoring benchmark problem; and it has been shown that it can identify the location and extent of damage with more accuracy than most other existing models. Keywords: Bayesian Updating, Condition Assessment of Structures, Modal Data, Visual Inspections, Finite Element Model, Bridges
PH.D in Structural Engineering, May 2013
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Title: THE CONTRIBUTIONS OF SPATIAL, VERBAL, AND ANALYTICAL SKILLS TO PROBLEM-SOLVING PERFORMANCE
Creator: Foster, Ardyth C.
Date: 2012-12-18, 2012-12
Description: ABSTRACT The purpose of this study was to examine the existence and strength of relationships between students’ cognitive skills and...
Show moreABSTRACT The purpose of this study was to examine the existence and strength of relationships between students’ cognitive skills and mathematical problem-solving performance. Specifically, relationships between students’ verbal, spatial, and analytical skills and their problem-solving performance on items that require a verbal response, items that require a spatial response, and overall problem-solving performance were investigated. A review of the literature also revealed assumptions of close links between verbal and logical/analytical skills, resulting in a lack of assessment of these skills as separate constructs. This study therefore sought to measure each of the cognitive skills separately in order to clearly establish the existence and strength of any pair-wise relationships among the cognitive skills. Ninety-eight students from the fifth- through eighth-grades were administered assessments of verbal skills, spatial skills, and logical/analytical skills, as well as a problem-solving instrument that consisted of a verbal (PST-Verbal) subtest and a spatial (PST-Spatial) subtest. The results indicated statistically significant relationships between students’ cognitive skills and problemsolving performance on the PST-Verbal subtest, the PST-Spatial subtest, and overall problem-solving performance. Surprisingly stronger relationships were found, however, between spatial skills and PST-Verbal performance than between verbal skills and PSTVerbal performance, and stronger relationships were found between verbal skills and PST-Spatial performance than between spatial skills and PST-Spatial performance. Statistically significant pair-wise relationships were also found among the cognitive skills, with the strongest pair-wise relationship existing between verbal and analytical viii skills. The relationship between verbal and spatial skills, although not as strong as the one that exists between verbal and analytical skills, was also quite strong.
PH.D in Mathematics Education, December 2012
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Title: TWO-DIMENSIONAL AND AXISYMMETRIC BUBBLE RISE USING THE LEVEL SET METHOD
Creator: Dominik S, Michael
Date: 2013, 2013-07
Description: Gas bubbles in liquids are important in many industries, including power gen- eration, steel making, as well as chemical and waste water...
Show moreGas bubbles in liquids are important in many industries, including power gen- eration, steel making, as well as chemical and waste water treatment. A fundamen- tal understanding of the bubble rising physics is helpful in many practical applica- tions. A new level set code for incompressible, multiphase ows using the vorticity- streamfunction formulation in both two-dimensional and axisymmetric cases has been developed. The level set method is well suited to treating multiphase ows having complex interface shapes that may undergo topological changes such as merging and splitting of bubbles. Previous numerical and experimental results for single and mul- tiple bubbles are used to determine the numerical parameters that should be used for the new code and to demonstrate the accuracy of the model. The shape and ter- minal velocities of air bubbles in mineral oil and water are found to duplicate other experimental and calculated results very closely. Results have been compared from two-dimensional and axisymmetric versions of the code for bubbles merging with var- ious surface tension. It is found that prior to merging of the bubbles, the results for velocities and bubble shapes are very similar. However, surface tension is found to have a greater in uence on the axisymmetric results. Once the bubbles merge, the combined bubble evolves toward the same shape and terminal velocity of a single bub- ble having the same volume. The initial acceleration of a single air bubble in water is analyzed and found to be approximately 3:3g, not 2g, which is the predicted value from added mass analysis based on potential ow theory. When the liquid density is increased, the acceleration is also found to increase.
PH.D in Mechanical and Aerospace Engineering, July 2013
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Title: EARLY CHILDHOOD RISK FACTORS FOR EXECUTIVE DYSFUNCTION IN A SAMPLE OF SCHOOL-AGED CHILDREN
Creator: Grahovec, Morgan Carey
Date: 2014, 2014-12
Description: The purpose of the present study was to explore whether early childhood factors influence executive function scores, as determined by...
Show moreThe purpose of the present study was to explore whether early childhood factors influence executive function scores, as determined by objective neuropsychological tests and subjective parent and teacher ratings, in a diverse sample of school age children. Data was collected longitudinally over four different visits that corresponded to childhood development (7.76 months, 20 months, 38 months, and 7 years of age). The independent variables examined in the present study included environmental, sociodemographic, and neuropsychological data from the first three time points. At Time 1, the independent variables were SES at Time 1, infant birth weight, maternal body mass index, parental stress at Time 1, and the psychomotor development score at Time 1. At Time 2 and Time 3, the independent variables were SES, parental stress, the sleep problems composite, the DSM-IV ADHD composite, and the psychomotor development index score. Results indicated that overall, maternal pre-pregnancy body mass index, the psychomotor development index score, and family socioeconomic status were the only significant predictors from the first three time points of variance in the Time 4 executive functions as measured by the neuropsychological assessments. The findings showed an inverse relationship between maternal BMI and neuropsychological executive functions, indicating that as BMI increased, executive functioning decreased. A positive relationship between family SES and neuropsychological EF was found, indicating that children from higher SES families performed better on measures of executive functions, as expected. Similarly, a positive relationship was found between psychomotor functions at Time 3 and executive functions at Time 4, which was also in the expected direction. In contrast, subjective parent stress and the DSM-IV ADHD scores were the only significant predictors of the Time 4 executive functions as measured by the parent and teacher ratings. An inverse relationship between parent stress and executive functions was found at all three initial time points, revealing that parents who experience more subjective stress also have children with lower executive functions per parent and teacher report at age 7. A positive relationship was shown between the DSM-IV ADHD composite at Time 3 and the parent/teacher composite score of executive functions at Time 4. This means that children with low executive functions per the parent/teacher composite at Time 4 also had parents and teachers who endorsed greater ADHD symptomatology at Time 3. Subjective parent stress was particularly notable because it was the only independent variable for either of the two dependent variables that was significant across all three of the initial time points. The longitudinal design of this study allowed for the confirmation of the hypothesis that there are significant variables in early childhood that are associated with executive functions later in life. This knowledge has important implications because the more that is understood about executive functioning in children, the more it will be possible to provide meaningful interventions that can maximize a child’s development of this critical skill set.
Ph.D. in Psychology, December 2014
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Title: COORDINATION OF STORAGE WITH RENEWABLE ENERGY RESOURCES IN POWER SYSTEMS
Creator: Khodayar, Mohammad Esmaeil
Date: 2012-07-16, 2012-07
Description: The ever-increasing penetration of variable wind energy in power systems affects the hourly dispatch of thermal power generation in...
Show moreThe ever-increasing penetration of variable wind energy in power systems affects the hourly dispatch of thermal power generation in electricity markets. The coordination of wind power generation units with pumped-storage hydro (PS) generation could relieve the variability of wind energy and increase its hourly dispatchability. In this dissertation, a coordination methodology for wind and pumped-storage hydro (PS) units in the dayahead operation planning of power systems is proposed. With coordination, the PS unit can offset intrahour wind energy imbalances (i.e., deviations from hourly schedules) and minimize wind energy curtailments. The wind-PS coordination based on the application of stochastic security-constrained unit commitment (Stochastic SCUC) is evaluated in which, the hourly bus- level coordinated scheduling of wind energy and PS is compared with the system-level coordinated operation strategies in the day-ahead scheduling of power systems. Volatility of wind generation can also reduce the profit in day-ahead market by imposing potential imbalance charges in a generating company (GENCO). The dayahead price-based scheduling strategy for the coordination of wind and storage units in a GENCO is proposed based on the stochastic price-based unit commitment (PBUC) which considers volatilities in day-ahead intra-hour market prices and wind power generation when scheduling wind and storage units. The increased utilization of Plugin Electric Vehicles (PEVs), which consume electricity rather than fossil fuel for driving, offers unique economic and environmental opportunities, and brings out new challenges to electric power system operation and planning. The proposed approach evaluates the effect of integrating a large number of electric vehicles (EVs) on power grid operation and control. The coordinated integration of aggregated PEV fleets and renewable energy sources (wind energy) in power systems is studied by stochastic security-constrained unit commitment (Stochastic SCUC) model, which minimizes the expected grid operation cost while considering the random behavior of the many PEVs. Finally, the role of high reliability distribution system (HRDS) in microgrid operations is evaluated. HRDS, which offers a higher operation reliability and fewer outages in microgrids, is applied to looped networks in distribution systems. The storage system would enhance the microgrid reliability while offering hourly ancillary services and demand response for reducing operation costs. The HRDS implemented at Illinois Institute of Technology (IIT) is used as a case study along with the local DER to increase the load point reliability and decrease the operation cost of the microgrid.
Ph.D. in Electrical Engineering, July 2012
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Title: IN SITU X-RAY ABSORPTION SPECTROSCOPY STUDY OF TIN ANODE NANOMATERIALS FOR LITHIUM-ION BATTERIES
Creator: Pelliccione, Christopher J.
Date: 2015, 2015-05
Description: Tin is an attractive alternative to replace traditional carbon based anodes in lithium-ion batteries (LIBs) due to the nearly three-fold...
Show moreTin is an attractive alternative to replace traditional carbon based anodes in lithium-ion batteries (LIBs) due to the nearly three-fold increase in theoretical capacity over carbon. However, metallic tin su↵ers from volumetric expansion of the crystal structure during initial lithium insertion that quickly degrades the material and reduces the performance of the battery. Various techniques have been previously investigated with the goal of suppressing this destructive expansion by incorporating oxygen or a lithium-inactive metal into the tin to provide structural support and mitigate volumetric expansion. These materials show increased capacity retention compared to metallic tin, but still su↵er from capacity fading. The nature of these structural degradations must be fully understood to permit engineering of materials that avoid these destructive tendencies and can be considered as viable options for LIBs. In situ X-ray absorption spectroscopy (XAS) measurements were acquired on Sn, SnO2, Sn3 O2(OH)2, Cu6Sn5 and Ni3Sn4 nanoparticle anodes for LIBs. Accompanying the electrochemical characterization conducted on each material, the local atomic structure was modeled as a function of potential during the first charge and also as a function of charged/discharged states for several cycles. The extended X-ray absorption fine structure (EXAFS) theoretical modeling included the first unambiguous observation of Sn-Li coordination numbers and atomic distances in tin-based anode materials. From correlating the electrochemical performance to the EXAFS analysis, the long-term capacity retention of tin-based anodes is dependent on the structural deformations that occur during the first charge. The conversion of oxygen to amorphous Li2O, and the network that it forms, has a dramatic e↵ect on the kinetics of the system and the stability of the local metallic tin structure.
Ph.D. in Physics, May 2015
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Title: IMPLICITLY-COUPLED ELECTROMECHANICAL AND ELECTROMAGNETIC TRANSIENT ANALYSIS
Creator: Zhang, Xu
Date: 2015, 2015-05
Description: The operation of an electrical power system involves continuous electromechanical and electromagnetic interaction of energy among the system...
Show moreThe operation of an electrical power system involves continuous electromechanical and electromagnetic interaction of energy among the system components. Under normal operation, the system behavior could be represented by voltage and current phasors in the frequency domain. However, the system may not work on the fundamental frequency following some fast transients (loss of generator, switching event, system disturbance and etc.), at this time we need specific tools to investigate the dynamic scenario. Transient stability (TS) simulator, also referred to as electromechanical transient simulator, running at time steps on the order of milliseconds and only capable of capturing the fundamental frequency transient, is used for the analysis of largescale networks. On the other hand the electromagnetic transient (EMT) simulator running at time steps on the order of microseconds, with detailed equipment modeling is capable of analyzing transients over a wider frequency spectrum; however, it is computationally onerous, so it is typically restricted to the analysis of small networks. An electromechanical-electromagnetic transient simulator is the combination of a TS simulator and an EMT simulator, inheriting the merits of both programs. The basic idea of an electromechanical-electromagnetic simulator is to decompose the power system into two broad categories: a large connected TS network (main network) and smaller EMT network (detailed subsystem). The main network is running on TS simulator while the detailed subsystem is running on the EMT simulator. The implicitly-coupled electromechanical and electromagnetic simulator has TS and EMT simulators coupled at the equation solution level, which could ensure the consistence of the solution between TS and EMT simulation. Instead of using fundamental frequency equivalent model of the main network in EMT simulation of implicitly-coupled electromechanical and electromagnetic simulator, a frequency dependent network equivalent (FDNE) model is utilized to preserve the non-fundamental frequency fast transient response of the main network. Along with the implementation of FDNE model, this research work also propose a new TS simulator that is capable of running three-phase transient stability simulation under fundamental and non-fundamental frequency simultaneously. Furthermore the performance of implicitly-coupled electromechanical-electromagnetic transient simulator could be improved with the implementation of this new TS simulator.
Ph.D. in Electrical and Computer Engineering, May 2015
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Title: EXPLOITING KNOWLEDGE IN UNSUPERVISED OPEN INFORMATION EXTRACTION
Creator: Merhav, Yuval
Date: 2012-12-03, 2012-12
Description: The extraction of structured information from text is a long-standing challenge in Natural Language Processing (NLP) which has been...
Show moreThe extraction of structured information from text is a long-standing challenge in Natural Language Processing (NLP) which has been reinvigorated with the ever- increasing availability of user-generated textual content Online. The ability to extract interesting and important pieces of information from text documents is crucial for large scale language understanding, which powers modern Web search engines. The eld of Open Information Extraction (Open IE) o ers a way to auto- matically discover relations from large and heterogeneous text collections. Since it is di cult to obtain adequate training data for Open IE, unsupervised approaches that rely on rules and clustering are popular. However, the major trend in unsupervised Open IE has been to borrow algorithms and low-level features from other applica- tions such as search, relying on previous work that has been proved to be successful in other domains. This thesis argues that it is essential to use domain and external knowledge in Open IE, and proposes several ways of doing it to achieve substantial performance improvements over state-of-the-art systems. We use three main knowledge sources: (1) a large corpus of unstructured text that is used to learn a language model over relations that can be incorporated into a weighting scheme that outperforms the common tf idf weighting scheme; (2) an external knowledge base such as Wikipedia that is used to extract ne-grained types of entities that yield better understanding of how relations are expressed in English; and (3) domain knowledge extracted from the blogosphere (e.g., the degree of a node in the network) that is used to improve performance at scale.
PH.D in Computer Science, December 2012
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Title: DESIGN OF A COVARIANCE MATRIX FITTER TO MEASURE THE ELECTRON ANTINEUTRINO OSCILLATION PARAMETERS USING NEUTRON HYDROGEN CAPTURE AT THE DAYA BAY EXPERIMENT
Creator: De Arcos Rodr´iguez, Jos´e Fernando
Date: 2015, 2015-12
Description: The Daya Bay experiment provided the first precision measurement of the third mixing angle of the Pontecorvo-Maki-Nakagawa-Sakata matrix (✓13)...
Show moreThe Daya Bay experiment provided the first precision measurement of the third mixing angle of the Pontecorvo-Maki-Nakagawa-Sakata matrix (✓13) using six detectors to determine the relative rates of correlated signals generated from gadolinium neutron capture and positron-electron annihilation gammas in the inverse beta decay process. An additional correlated hydrogen neutron capture signal is produced in the Daya Bay detectors. Its analysis has the potential of producing an independent measurement of the electron antineutrino oscillation parameters. In this thesis a fitter has been designed to measure ✓13 and the squared mass di↵erence (#m2 ee) using the shape information of the hydrogen neutron capture signal generated in the Daya Bay experiment detectors. The main challenges of the hydrogen capture signal are the high accidental background rates in the lower energy region, and hydrogen’s neutron capture cross-section being much lower than gadolinium’s. In order to have a significant signal, we had to use more aggressive selection cuts than those applied in the gadolinium neutron capture analysis, and the fiducial volume was expanded by including the gadolinium-free gamma catcher region. Both background and detector systematic uncertainties studies have been repeated for the new hydrogen signal conditions. The results of these studies have been used to produce the corresponding covariance matrices that account for the uncertainties in a covariance matrix fitter. The fitter is customizable, i.e., energy binning, antineutrino detector configuration, data periods to be fitted, reactor periods, detector response matrices and predictions can be configured using a graphical user interface, providing versatility for further research. The fitter performance has been tested in the two dimensional parameter space S ⇥ D, where S = !sin2(2✓13) 2 [0, 0.002, 0.004, ...0.2]} and D = {#m2 ee 2 [0.0015, 0.00152, 0.00154...0.0035]}, using nominal and statistically fluctuated antineutrino spectrum predictions.
Ph.D. in Physics, December 2015
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Title: SELECTION TEST SECURITY: ARE SIMULATIONS MORE SUSCEPTIBLE TO TEST SECURITY CONCERNS THAN TRADITIONAL ASSESSMENTS?
Creator: Daisley, Rebecca Roller
Date: 2015, 2015-12
Description: The current study examined whether information about the job simulation portion of a selection assessment battery is more susceptible to a...
Show moreThe current study examined whether information about the job simulation portion of a selection assessment battery is more susceptible to a test security threat than more traditional assessments, where test security is threatened when assessment content is shared. Participants were asked to play the role of a job candidate for a customer service representative. They were given three assessments: a cognitive ability test, a personality inventory, and a job simulation. After completing the assessments, participants were asked to write an e-mail to a hypothetical friend who will also be applying for the job, and include any information that would help their friend in the application process. It was hypothesized that the most information and the most useful information shared by participants would be about the job simulation portion of the assessment battery. The findings supported the hypotheses, suggesting that job simulations are more susceptible to information sharing by applicants than the other assessments, and therefore are exposed to a greater test security threat. The discussion includes implications for practice.
Ph.D. in Psychology, December 2015
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Title: CHAIN BY CHAIN MONTE CARLO SIMULATIONS FOR POLYMERIZATION PROCESSES
Creator: Demirel, Derya
Date: 2016, 2016-05
Description: Predicting chain microstructure became an important task for polymer scientists. Polydisperse nature of polymer molecules makes it an...
Show morePredicting chain microstructure became an important task for polymer scientists. Polydisperse nature of polymer molecules makes it an interesting research area. In this work, a new method, called “Chain-by-Chain Monte Carlo Method” (CBCMC), is presented for simulating chain microstructures one-by-one or chain-by-chain. To the best of our knowledge, it is a new approach for the simulation of chain microstructures. It is a hybrid deterministic-stochastic method that uses the best of two worlds by obtaining information on the mean-field background environment as concentrations of polymer populations and small molecules (only) from the deterministic solver and using it in the stochastic part of the algorithm. Deterministic solver can employ any method that provides this data and in this work uses method of moments. With this information, stochastic part of the algorithm employs kinetic Monte Carlo algorithm to simulate chains one-by-one. The computational load of simulating the whole ensemble is eliminated by getting the mean-field background information from deterministic solvers as concentrations of polymer populations and small molecules at certain time intervals. CBC-MC is suited for chemistries, or situations in which the chain architecture develops slowly with respect to the background environment such as controlled reversible-deactivation radical polymerizations. This method is applied to two case studies for synthesis of linear gradient copolymers. First case study is a styrene/ methyl methacrylate copolymerization by nitroxide-mediated polymerization with forced gradient techniques and the second one is the synthesis of methyl methacrylate/ methyl acrylate hyberbolic gradient copolymerization by atom-transfer radical polymerization again with forced gradient techniques. Gradient distribution of chain properties is analyzed in all cases since it is relatively more challenging and interesting. Chain properties such as number average chain length, weight average chain length, polydispersity index, cumulative and instanteneous copolymer compositions, full molecular weight distributions and sequence length distributions are obtained and compared to results from method of moments and kinetic Monte Carlo methods for di↵erent sample sizes. Results were in good agreement with wellestablished method of moments and kinetic Monte Carlo methods. Importance of simulating chain microstructure rather than average properties is made clear. Simulation times were reduced by at least a factor of six compared to kinetic Monte Carlo method. Results confirm that if applicable, full information regarding the microstructure of chains can be obtained using this method with reduced simulation times and smaller sample sizes. This method is also applied to non-linear copolymerization of acrylamide/N,N-methylenebis(acrylamide) (AM/BisAM) leading to gelation. The e↵ect of a gradient distribution of pendant double bonds along the primary chains on the simulated portion of gel molecules is investigated with the aim of detecting the macro-heterogeinities. Five cases are studied with di↵erent feeding policies but same total number of comonomers introduced to each of them. Primary chain results are compared with MOM for cumulative and instantaneous BisAM compositions, crosslink and PDB densities and found to be in excellent agreement. Further investigations are done on primary chain microsturctures to better understand multiple phenomena going on in these systems such as the age distribution of crosslinking points and PDBs, density of crosslinking points and PDBs in monomer bins along the primary chains and average segment lengths. It has been found that a gradient in PDB distribution along the primary chains can introduce heterogeneities into the gel molecules in surface-bound type polymerizations where primary chains within gels are aligned in the same direction but these heterogeneities seem to be disappearing in bulk polymerizations where the chain alignments are random.
Ph.D. in Chemical Engineering, May 2016
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Title: THE EFFECT OF NON-NATIVE ACCENTS ON THE EVALUATION OF APPLICANTS DURING AN EMPLOYMENT INTERVIEW: THE DEVELOPMENT OF A PATH MODEL
Creator: Deprez-sims, Anne-sophie
Date: 2012-04-23, 2012-05
Description: As the workplace becomes increasingly global, organizations are more likely to employ persons from other countries whose accents clearly...
Show moreAs the workplace becomes increasingly global, organizations are more likely to employ persons from other countries whose accents clearly identify them as different from the local workforce. Understanding the impact of accents in the workplace is important because accents can be salient in the same way as ethnicity, age, gender, and skin color and may be a source of employment discrimination. The present study looked at the influence of accents on the evaluation of job applicants during an interview for a human resource manager position. In addition, a path model was developed to understand the accent condition-hiring recommendation relationship. Participants were asked to evaluate an applicant with one of three accents (Midwestern, French, Mexican) at two understandability levels (low and high) by listening to an audiofile. The results showed that the applicant with the Midwestern accent was seen as more hireable than the applicant with the French-low understandability accent but contrary to expectations the applicant with the Mexican accent (low or high level of understandability) was not perceived as significantly less hireable than the French applicant. The path model indicated that the accent condition-hiring recommendation relationship was mediated by similarity, interpersonal attraction and understandability.
Ph.D. in Psychology, May 2012
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Title: ELECTROCHEMICAL AND THERMAL BEHAVIOR OF ENERGY STORAGE AND CONVERSION SYSTEMS: LITHIUM ION BATTERIES AND PEM FUEL CELLS
Creator: Ha, Seonbaek
Date: 2015, 2015-05
Description: In this dissertation, three major topics in electrochemical energy storage and conversion systems are discussed. Lithium-ion batteries as...
Show moreIn this dissertation, three major topics in electrochemical energy storage and conversion systems are discussed. Lithium-ion batteries as electrochemical energy storage and catalyst support in proton exchange membrane (PEM) fuel cells as an electrochemical energy conversion system has been investigated. Most work was done to understand the mechanism of an electrochemical reaction and performance degradation in both systems. After that, it was essential to overcome the technical challenges. The thermal stability of lithium-ion cells has been characterized by a novel cathode and anode material with an electrolyte. For electrochemical energy storage, LiFePO4 as a cathode material in a lithium-ion battery has been investigated by various electrochemical techniques. Generally, the electrode consists of an active material, polymer binder, and conducting agents. The electrode material compositions can affect the electrochemical performance by changing the ratio of carbon content to binder or active material content. The LiFePO4 electrodes were optimized by several factors; electronic conductivity, over voltage during discharge, area specific impedance, hybrid pulse power, and energy density. Silicon is a promising material as a novel anode material in lithium-ion batteries. The importance of selecting a polymer binder among various binders has been addressed by the experiments. The additive in the electrolyte also affects the interfacial property between the solid active material and the electrolyte. The effect of fluoroethylene carbonate (FEC) additive was investigated by electrochemical and physical characterization. The thermal stability of the silicon anode was studied by varying the FEC concentration. Metal oxide, as a non-carbon catalyst support in the PEM fuel cell, was chosen and developed to replace the carbon support for better electrochemical durability. The electronic conductivity; Brunauer, Emmett and Teller (BET) surface area; stability in acid media; and the electrochemical stability of fabricated Zr-doped In2O3 were evaluated.
Ph.D. in Chemical Engineering, May 2015
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Title: FIBRILLIZED PEPTIDE HYDROGELS AND MICROGELS FOR 3D CELL CULTURE AND TISSUE ENGINEERING
Creator: Tian, Ye “field”
Date: 2013, 2013-12
Description: Self-assembling peptide-based nanofibers and hydrogels have been widely applied as cell delivery vehicles, vaccine adjuvants, and scaffolds...
Show moreSelf-assembling peptide-based nanofibers and hydrogels have been widely applied as cell delivery vehicles, vaccine adjuvants, and scaffolds for tissue engineering and 3D cell culture. Self-assembling peptides, owing to their specific sequences, self-associate into nanofibers when dissolved in aqueous buffers. Highly concentrated peptide solutions can form hydrogels, when triggered by increased ionic strength, pH adjustment, and/or change in temperature. The advantages of these peptide materials are that 1) they are chemically defined, which minimizes their batch-to-batch variances, 2) they are modular, which allows for ease in synthesis and the inclusion of multiple different functional ligand-conjugated peptides, 3) they are controllably immunogenic. Although the general feasibility of self-assembling peptide hydrogels for 3D cell encapsulation has been demonstrated by commercial products and several research groups including our own, these materials are not without their shortcomings. Their application as artificial matrices is hindered by 1) their relatively low mechanical strength and vulnerability to fracture, 2) their extreme thermodynamic stability and lack of mechanisms for degradation, and 3) their temporary cytotoxicity during the cell encapsulation processes. In this thesis, I have designed new peptide/depsipeptide sequences, as well as encapsulation processes, to address the above-mentioned limitations. Briefly, I have designed microgels for cell encapsulation as an alternative to bulk encapsulation, which partly solved the fracture-in-gel problem. I have designed ester bond-containing depsipeptides to impart highly controllable biodegradation properties to the materials. I have also designed peptides whose gelation can be triggered by minor pH adjustment, to achieve high degrees of cell survival in the early steps of cell xiii encapsulation.
PH.D in Biomedical Engineering, December 2013
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Title: SOCIAL SKILLS AND ACADEMIC ACHIEVEMENT: DIFFERENCES BETWEEN AFRICAN AMERICAN, CAUCASIAN, AND LATINO STUDENTS
Creator: Filerman, Stacey
Date: 2011-08, 2011-07
Description: Previous studies have demonstrated a significant relationship between social skills and academic achievement (McClelland, Morrison, & Holmes,...
Show morePrevious studies have demonstrated a significant relationship between social skills and academic achievement (McClelland, Morrison, & Holmes, 2000; Payton et al., 2008; Wentzel 1993). This relationship may be due to Vygotsky‟s and Bandura‟s social learning theories, in which learning occurs through observation, imitation, and interaction with one‟s environment (Bandura, 1997; Vygotsky, 1978). Large differences in academic achievement among minority and non-minority students in the United States have been documented for over three decades (Coleman, 1968; National Center, 1978- 1998). Current research examining differences in social skills and academic achievement by race/ethnicity is limited in that dichotomous comparisons have been made between Caucasian and African American, or minority students (Malecki & Elliot, 2002). Social skills measures have also been questioned for their construct validity among minorities (Van Horn, Atkins-Burnett, Karlin, Landesman Ramey, & Snyder, 2007). The current study attempts to expand the understanding of the relationship between social skills and academic achievement in African American, Caucasian, and Latino third, fourth, and fifth grade students. In particular, this study examined teacherand self-rated social skills, reading and mathematics achievement, English proficiency, an estimate of intelligence, and socio-economic status. The results of the current study revealed significant differences in teacher-rated social skills by Race/Ethnicity and no differences in self-ratings. Significant group differences were found also found in reading and not math. Regression analyses revealed teacher-rated social skills did not mediate the relationship between race/ethnicity and academic achievement.
Ph.D. in Psychology, July 2011
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Title: CERTIFIED REHABILITATION COUNSELORS’ WILLINGNESS TO ADDRESS SEXUALITY-RELATED CONCERNS WITH CLIENTS WITH AUTISM SPECTRUM DISORDER
Creator: Easton, Amanda B.
Date: 2015, 2015-05
Description: Certified Rehabilitation Counselors (CRCs) are professionals who are responsible for supporting the rights and independence of people with...
Show moreCertified Rehabilitation Counselors (CRCs) are professionals who are responsible for supporting the rights and independence of people with disabilities. CRCs provide a number of services to those with a number of disabilities including, but not limited to, mental health counseling, vocational counseling, advocacy, and psychoeducation. Given the plethora of complexities associated with the wide range of disabilities people experience, CRCs are professionals who need to have a variety of skills, knowledge, and competencies. In recent years, the rates of Autism Spectrum Disorder (ASD) have increased drastically and issues related to the disorder have become more widely known than ever before. It is likely, given the rates of ASD diagnoses and the fact that CRCs work with individuals with disorders like ASD, that CRCs will interact with someone who has ASD at some juncture in their professional tenure. ASD is characterized by impaired social functioning, verbal and non-verbal communication, and restricted and repetitive behavior. In some circumstances ASD is coupled with cognitive deficits, speech and language delays and deficits, and behavioral challenges. Still, those with ASD experience the same hormonal changes as anyone else during puberty and maturation and are impacted by sexuality. For CRCs sexuality is typically considered a part of culture and having a strong multicultural competency is expected by the governing agencies that dictate CRC ethical practice. Furthermore, few studies that explore CRCs attitudes and intentions have used the theoretical framework of the Theory of Planned Behavior. This study attempted to explore the factors that contribute to CRCs willingness to address sexuality-related concerns for clients with ASD. This study used a sample of 99 CRCs throughout the United States. The predictors included familiarity, attitudes towards sexuality for people with ASD, subjective normative beliefs, and control beliefs, while controlling for participants’ age, gender, training around sexuality, and spirituality. A hierarchical regression analysis was used to analyze whether these factors were predictive of CRCs willingness to address sexuality-related issues for clients with ASD. Results demonstrated that gender and familiarity were initially significant predictors; however, when controlling for the TPB variables, the variance in willingness was better accounted for by subjective normative beliefs and control beliefs. Additionally, the CRCs in this study were asked to rate 11 areas of sexuality that they were most and least comfortable with. A one-way repeated measures ANOVA along with follow-up contrasts was completed. The CRCs in this study reported feeling the highest level of comfort with addressing sexual harassment and sexuality in the workplace and were least comfortable addressing masturbation and sexual behaviors and preferences. Further, based on a Spearman’s rank analysis, the vignette case example showed that CRCs thought that social skills development was the most important intervention, followed by emotional support, sexual identity, self-esteem, and job training, though scores on social skills did not differ significantly from the other interventions.
Ph.D. in Psychology, May 2015
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Title: THE STRUCTURAL BASIS OF MYOFILAMENT LENGTH DEPENDENT ACTIVATION
Creator: Hsu, Karen Hsiaoman
Date: 2014, 2014-12
Description: Titin-based passive tension is one of the mechanisms that modulate myofilament length dependent activation, the phenomenon that underlies the...
Show moreTitin-based passive tension is one of the mechanisms that modulate myofilament length dependent activation, the phenomenon that underlies the so-called Frank Starling Law of the Heart. The Greaser N2BA-G rat model, with a homozygous autosomal mutation in the titin gene, produce a longer isoform of titin that produce much less passive tension as well as a reduced degree of LDA. This provides a useful tool to test whether titin modulates sarcomere structure with changes in sarcomere length. Here we assessed sarcomere structure using small angle X-ray diffraction of intact, twitching papillary muscle in the diastolic phase of contraction at short and long sarcomere length. Comparison of our results from wild type and titin mutant rats indicated that the equatorial intensity ratio, I11/I10, decreases in both wild type and the titin mutant rats with increases in length indicating that the myosin heads are more associated with the thick filament backbone than the thin filament at long lengths. Analysis of the first myosin layer line shows that there is a radially inward movement of myosin heads in WT myocardium but not in the titin mutant when stretched. Difference electron density maps show the thick filament densities in wild type increases more than in titin mutant rats and that the densities of the thin filament are less in the titin mutant rats. Our data suggest, therefore, that increased calcium sensitivity at longer sarcomere length is not due to a radial extension of the myosin heads at long length. Rather, it is associated with transmission of titin-based passive tension from the thick filaments to the thin filament, resulting in increased ordering of the myofilaments at the hexagonal lattice positions requiring some sort of communicating structure, presumably crossbridges, between the thick and the thin filaments as part of the length transduction mechanism behind LDA. The X-ray diffraction studies showed that there are gross troponin structural cahnges when muscle is stretched indicating that troponin is an important regulator of LDA in the myofilaments. But the precise way in which troponin regulates muscle contraction is only partly understood. In the research reported here, we investigated the effects of cTnI phosphorylation of sites in human cardiac tissue using site-directed mutagenesis. Serine and threonine were replaced by aspartic acid (D) or glutamic acid (E) to mimic the phosphorylated state. Six recombinant human cardiac troponin complexes (hcTn), containing either hcTnI-WT, hcTnI-S5/6D, hcTnI-S23/24D, hcTnI-S42/44E, hcTnI-T143E and hcTnI-S150D were exchanged into skinned human cardiac fibers. Force and ATPase activity was measured as function of [Ca2+] at short and long sarcomere length (SL=2.0 and 2.3um). We found that LDA in the hcTnI-S150D substitution was attenuated, and was unchanged with the other sites. CD, as indexed by tension cost was decreased for hcTnI-S42/44E and hcTnI-S150D, and was unaffected for the other site substitutions. While some of these results were consistent with previous findings form rodent myocardium, others were not, suggesting that one should use caution in extrapolating from results in rodetn cardiac tissue to human cardiac tissue.
Ph.D. in Biological and Chemical Sciences, December 2014
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