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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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Title: ELECTROCHEMICAL, TRANSPORT AND THERMAL INVESTIGATION OF NOVEL ELECTROLYTES AND ELECTRODES FOR LITHIUM-ION AND MAGNESIUM-ION BATTERIES
Creator: Benmayza, Aadil
Date: 2014, 2014-12
Description: Energy conversion and energy storage are becoming indispensable in today’s society due to the increased demand for immobile and mobile power....
Show moreEnergy conversion and energy storage are becoming indispensable in today’s society due to the increased demand for immobile and mobile power. Cathode material is considered as the only source of energy in the electrochemical cell for secondary battery and thus the quantity of energy of the battery is largely determined by the type of the cathode’s chemistry and its amount used as well. Electrolyte has also a significant impact on the electrochemical performance of the battery. Its properties such as ionic conductivity and transference number play a substantial role in the transport of energy between the cathode and the anode. Moreover, the electrolyte can also limit the accessibility of the active charged ions into the active material through the formation of a Solid Electrolyte Interface (SEI). In addition to the importance of energy, safety is another critical element in the determination of the battery’s quality. Cathode material and non-aqueous electrolyte are two major dimensions of the safety in the design of secondary battery. For instance, in the presence of heat (due to thermal, mechanical, or electrical abuse), the electrolyte can ignite fire if the cathode material releases the oxygen. Therefore, the cathode materials and electrolytes are both central factors in the determination of battery energy and safety. Nowadays, lithium-ion batteries are widely used as power source in many applications; however, their maximum energy density (400Wh/Kg) is not sufficient enough to meet the demands of high power applications such as electric vehicles owing to the limited driving range caused by current lithium-ion batteries. Furthermore, safety concerns have been raised after several incidents have been reported recently. Therefore, improving the safety of lithium-ion battery systems through the formulation of non-flammable electrolytes and synthesizing stable electrodes are highly required for high thermal stability. In contrast, fulfilling the long driving range requires other battery systems that provide higher energy density. The large energy density of Mg metal (3832 mAh/cm3) opens a new horizon toward future potential energy storage system, which is a very promising candidate to overcome the long driving range issue and thus needs to be investigated for its potential use as rechargeable battery. In this present thesis, thermal stability of lithium-ion cells is examined through the use of Fluoro Ethylene Carbonate (FEC) as non-flammable co-solvent with Ethylene Carbonate (EC) on lithium-nickel-cobalt-aluminum-oxide cathode (LiNi0.8Co0.15Al0.05O2). This cathode chemistry was deliberately chosen because of its low thermal stability due to the oxidation of Ni+3 to Ni+4 upon charging. Additionally, optimization of the cathode composition (active material, conducting agent, binder) was examined for high energy and power. Lithium iron phosphate (LiFePO4) was chosen for this study because of its high thermal stability against the liberation of oxygen. Electrolytic properties of a magnesium organohaloaluminate electrolyte were investigated in order to understand their role and effect on the magnesium deposition process. Electrochemical and thermal study of bismuth material as a potential negative electrode for magnesium-ion cell under the use of magnesium organohaloaluminate electrolyte was also performed. Moreover, a thermal modeling was performed through the use of Isothermal-Micro-Calorimeter (IMC) technique to identify the sources of heat released during the magnesiation and demagnesiation of bismuth electrode.
Ph.D. in Chemical Engineering, December 2014
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Title: SUPERVISED AND INTERACTIVE IMAGE SEGMENTATION TECHNIQUES WITH AN APPLICATION TO PROSTATE CANCER
Creator: Artan, Yusuf Oguzhan
Date: 2013, 2013-05
Description: Prostate cancer is a leading cause of cancer death for men in the United States. Fortunately, the survival rate for early diagnosed patients...
Show moreProstate cancer is a leading cause of cancer death for men in the United States. Fortunately, the survival rate for early diagnosed patients is relatively high. Accurate prostate cancer localization with noninvasive imaging using MRI can be used to guide biopsy, radiotherapy, and surgery as well as to monitor disease progression. However, in general, a single type of MRI is not sufficient for reliable tumor localization. As an alternative, multispectral MRI, i.e., the use of multiple MRI-derived datasets, has emerged as a promising noninvasive imaging technique for the localization of prostate cancer; however almost all studies are with human readers. There is a significant inter and intra-observer variability for human readers, and it is substantially difficult for humans to analyze the large dataset of multispectral MRI. To solve these problems, this thesis presents various novel supervised and semi- supervised (interactive) segmentation techniques. Initially, we develop a supervised segmentation method by combining conditional random fields (CRF) and support vector machines (SVM) with a cost-sensitive framework, and show that proposed method further improves classical and cost-sensitive SVM results by incorporating spatial information. Next, we propose an extension of popular semi-supervised seg- mentation method, namely random walker (RW) algorithm, with automated seed initialization for multispectral MRI images. We also present an automated shape and boundary based segmentation approach for prostate segmentation from T2-weighted MRI. Proposed method is based on a banded geocuts algorithm that utilizes bound- ary and shape information to yield prostate segmentation. Finally, we develop a novel method that has the ability to design classifiers obtained from one imaging protocol and/or MRI device to be used on a dataset from another protocol and/or imaging device. In order to evaluate the performance of the proposed methods, we utilize multispectral MRI datasets acquired from 21 biopsy-confirmed cancer patients. Our results show that multispectral MRI helps to increase the accuracy of prostate cancer xiv localization when compared to single MR images; and that using advanced proposed methods for prostate cancer localization performs better than available methods in the literature.
PH.D in Electrical Engineering, May 2013
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Title: AUTOMATED MANIPULATION OF NANOSCALE STRUCTURES VIA AN ATOMIC FORCE MICROSCOPE
Creator: Xu, Kangmin
Date: 2013, 2013-05
Description: As a useful tool for both imaging and modifying nanoscale structures, atomic force microscopes (AFM) have drawn many researchers’ attention,...
Show moreAs a useful tool for both imaging and modifying nanoscale structures, atomic force microscopes (AFM) have drawn many researchers’ attention, but there are still many challenges such as lack of visual feedback during manipulation. In this dissertation, an AFM based nano manipulation system has been developed to modify the nanoscale structures including manipulation of nano particles, carbon nanotubes (CNTs) and indentation of the polymer substrate. These operations have been further assisted by real-time feedback such that AFM can be used to image, sense and manipulate nanoscale objects simultaneously. To address critical issues in AFM based nano manipulation, several methods have been developed to enhance the process of manipulation. In nano particle manipulation, a method called sequential parallel pushing (SPP) is presented for efficient and automated nano particle manipulation. Instead of using tip scanning to fully locate the particle center, this method uses contact loss detection to get the longitudinal position of particle and one scan line perpendicular to the pushing direction to determine the lateral position of the particle center. In nano indentation, computer-aided design (CAD) geometry processing has been integrated with an AFM based nano indentation process which enables the fabrication of complex geometric features. Machining parameters have been investigated and procedure to determine them have been demonstrated. In the localization of deformable nanoscale objects, two localization methods for localizing CNTs and nanowires have been introduced. They can perform accurate positioning and reconstruction of sample shapes while being manipulated. Successive manipulation strategies thus can be developed based on the developed fast localization schemes.
PH.D in Mechanical Engineering, May 2013
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Title: LEADING IN UNCERTAIN TIMES: WHAT DRIVES FOLLOWERS' PERFORMANCE?
Creator: Arena, Fernando Lobo
Date: 2016, 2016-05
Description: Using a sample of 109 managers and 307 direct reports from a global financial services firm headquartered in the United States, we examined...
Show moreUsing a sample of 109 managers and 307 direct reports from a global financial services firm headquartered in the United States, we examined how trustworthiness affected the relationship between authentic leadership and performance in followers. Additionally, we examined how trustworthiness drives performance in an environment of strategic and structural uncertainty. Our findings indicate that authentic leadership drives follower performance and that this relationship may be mediated by benevolence. However, in a post hoc analysis we did show that benevolence mediated the relationship between relational transparency and performance. While not conclusive, there is also evidence to suggest that structural uncertainty moderates the relationship between benevolence and performance. In an environment of high structural uncertainty, followers that perceive their leaders as benevolent tend to outperform other followers.
Ph.D. in Psychology, May 2016
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Title: AUDITORY PROCESSING AND THE EXTRACTION OF SOCIAL EMOTIONAL CUES IN AUTISM
Creator: Demopoulos, Carly
Date: 2013, 2013-07
Description: There is increasing evidence that there are deficits in vocal affect recognition abilities in some individuals diagnosed with Autism Spectrum...
Show moreThere is increasing evidence that there are deficits in vocal affect recognition abilities in some individuals diagnosed with Autism Spectrum Disorders (ASDs) and that sensory deficits are also common in these individuals. Little research, however, has focused on the relation between atypical auditory processing and vocal affect recognition abilities. The aim of this study was to examine if there was an association between cortical auditory processing and vocal affect recognition ability, and, in turn, to determine if vocal affect recognition ability was related to parent report of social and leadership skills. First, peripheral auditory processing was examined in a sample of 28 5-18 yearold (mean = 11.48) children and adolescents with an ASD. Vocal affect recognition was assessed by the paralanguage subtests of the Diagnostic Analysis of Nonverbal Accuracy (DANVA), and magnetoencephalography (MEG) was used to evaluate cortical electrophysiological processing in relation to auditory stimuli. Parent-report was used to assess social skills and leadership with these subtests on the Behavior Assessment Scale for Children-2. Correlational analyses indicated that there were no significant relations between peripheral auditory processing and DANVA scores. Results of hierarchical regression analyses indicated that, after controlling for age, language ability, and IQ, the measures of cortical auditory processing contributed a significant additional 19% of the variance in DANVA-2 scores. Specifically, left hemisphere response latency and right hemisphere rapid auditory processing were related to vocal affect recognition. They also indicated that DANVA-2 scores contributed a significant additional 30% of the variance in parent-rated social skills after controlling for language ability and IQ. However, DANVA-2 scores did not contribute significantly to leadership skills. xi This was the first study to use magnetoencephalography (MEG) to assess auditory evoked fields in relation to vocal affect recognition and to show that there is an association between specific features of cortical auditory processing and vocal affect recognition. These results suggest that the ability to respond to and efficiently process rapidly presented auditory information may be important in extracting affective cues from speech, and for individuals on the autism spectrum, impairment in these abilities may contribute to difficulty in vocal affect recognition.
PH.D in Psychology, July 2013
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Title: PHYSICS OF LIMITING PHENOMENA IN SUPERCONDUCTING MICROWAVE RESONATORS: VORTEX DISSIPATION, ULTIMATE QUENCH AND QUALITY FACTOR DEGRADATION MECHANISMS
Creator: Checchin, Mattia
Date: 2016, 2016-12
Description: Superconducting niobium accelerating cavities are devices operating in radiofrequency and able to accelerate charged particles up to energy of...
Show moreSuperconducting niobium accelerating cavities are devices operating in radiofrequency and able to accelerate charged particles up to energy of tera-electron-volts. Such accelerating structures are though limited in terms of quality factor and accelerating gradient, that translates—in some cases—in higher capital costs of construction and operation of superconducting rf accelerators. Looking forward for a new generation of more affordable accelerators, the physical description of limiting mechanisms in superconducting microwave resonators is discussed. In particular, the physics behind the dissipation introduced by vortices in the superconductor, the ultimate quench limitations and the quality factor degradation mechanism after a quench are described in detail. One of the limiting factor of the quality factor is the dissipation introduced by trapped magnetic flux vortices. The radio-frequency complex response of trapped vortices in superconductors is derived by solving the motion equation for a magnetic flux line, assuming a bi-dimensional and mean free path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the bell-shaped trend as a function of the mean free path, in agreement with the experimental data observed. Such bell-shaped trend of the surface resistance is described in terms of the interplay of the two limiting regimes identified as pinning and flux flow regimes, for low and large mean free path values respectively. The model predicts that the dissipation regime—pinning- or flux-flow-dominated—can be tuned either by acting on the frequency or on the electron mean free path value. The effect of different configurations of pinning sites and strength on the vortex surface resistance are also discussed. Accelerating cavities are also limited by the quench of the superconductive state, which limits the maximum accelerating gradient achievable. The accelerating field limiting factor is usually associated to the superheating field, which is intimately correlated to the penetration of magnetic flux vortices in the material. Experimental data for N-doped cavities suggest that uniform Ginzburg-Landau parameter cavities are statistically limited by the lower critical field, in terms of accelerating gradient. By introducing a Ginzburg-Landau parameter profile at the cavity rf surface—dirty layer—the accelerating gradient of superconducting resonators can be enhanced. The description of the physics behind the accelerating gradient enhancement as a consequence of the dirty layer is carried out by solving numerically the Ginzburg-Landau equations for the layered system. The enhancement is showed to be promoted by the higher energy barrier to vortex penetration, and by the enhanced lower critical field. Another serious threat to the quality factor during the cavity operation is the extra dissipation introduced by the quench. Such quality factor degradation mechanism due to the quench, is generated by the trapping of external magnetic flux at quench spot. The purely extrinsic origin of such extra dissipation is proven by the impossibility of decrease the quality factor by quenching in a magnetic field-free environment. Also, a clear relation of the dissipation introduced by quenching to the orientation of the applied magnetic field is observed. The full recover of the quality factor by re-quenching in compensated field is possible when the trapped flux at the quench spot is modest. On the contrary, when the trapped magnetic flux is too large, the quality factor degradation may become irreversible by this technique, likely due to the outward flux migration beyond the normal zone opening during the quench.
Ph.D. in Physics, December 2016
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Title: MICROGRIDS AND DISTRIBUTED GENERATION SYSTEMS: CONTROL, OPERATION,COORDINATION AND PLANNING
Creator: Che, Liang
Date: 2015, 2015-07
Description: Distributed Energy Resources (DERs) which include distributed generations (DGs), distributed energy storage systems, and adjustable loads are...
Show moreDistributed Energy Resources (DERs) which include distributed generations (DGs), distributed energy storage systems, and adjustable loads are key components in microgrid operations. A microgrid is a small electric power system integrated with onsite DERs to serve all or some portion of the local loads and connected to the utility grid through the point of common coupling (PCC). Microgrids can operate in both gridconnected mode and island mode. The structure and components of hierarchical control for a microgrid at Illinois Institute of Technology (IIT) are discussed and analyzed. Case studies would address the reliable and economic operation of IIT microgrid. The simulation results of IIT microgrid operation demonstrate that the hierarchical control and the coordination strategy of distributed energy resources (DERs) is an effective way of optimizing the economic operation and the reliability of microgrids. The benefits and challenges of DC microgrids are addressed with a DC model for the IIT microgrid. We presented the hierarchical control strategy including the primary, secondary, and tertiary controls for economic operation and the resilience of a DC microgrid. The simulation results verify that the proposed coordinated strategy is an effective way of ensuring the resilient response of DC microgrids to emergencies and optimizing their economic operation at steady state. The concept and prototype of a community (networked) microgrid that interconnecting multiple microgrids in a community are proposed. Two works are conducted. For the coordination, novel three-level hierarchical coordination strategy to coordinate the optimal power exchanges among neighboring microgrids is proposed. For the planning, a multi-microgrid interconnection planning framework using probabilistic minimal cut-set (MCS) based iterative methodology is proposed for enhancing the economic, resilience, and reliability signals in multi-microgrid operations. The implementation of high-reliability microgrids requires proper protection schemes that effectively function in both grid-connected and island modes. This chapter presents a communication-assisted four-level hierarchical protection strategy for highreliability microgrids, and tests the proposed protection strategy based on a loop structured microgrid. The simulation results demonstrate the proposed strategy to be an effective and efficient option for microgrid protection. Additionally, microgrid topology ought to be optimally planned. To address the microgrid topology planning, a graph-partitioning and integer-programming integrated methodology is proposed. This work is not included in the dissertation. Interested readers can refer to our related publication.
Ph.D. in Electrical and Computer Engineering, July 2015
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