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Title: CO2 CAPTURE AND HYDROGEN PRODUCTION IN SORBENT ENHANCED WATER-GAS SHIFT (SEWGS) PROCESS WITH REGENERABLE SOLID SORBENT
Creator: Zarghami Khanehsar, Shahin
Date: 2015, 2015-07
Description: Carbon dioxide emission from fossil fuel combustion and its impact on global warming is one of the most critical environmental issues nowadays...
Show moreCarbon dioxide emission from fossil fuel combustion and its impact on global warming is one of the most critical environmental issues nowadays. Coal as a main source of produce energy is the most CO2-intensive fossil fuel. Advanced power generation processes that use gasification technology, such as Integrated Gasification Combined Cycle (IGCC), which offer higher efficiency, are among the leading contenders for power generation in the 21st century. In an IGCC process, because of high pressure, carbon dioxide in the fuel gas is at higher concentration, which can be captured and sequestered at lower costs. Utilization of regenerable MgO-based sorbents has been shown to be an effective method for capturing CO2 from gasification-based processes at elevated temperatures and pressures (i.e. p > 20 atm and 330° < T < 450°C). Low cost MgO based sorbent can be prepared through modification of natural dolomite. The reactivity of the sorbent in carbonation/regeneration cycles has a significant impact on the economics of the proposed regenerable process. Although the sorbent can be regenerated in successive cycles, the sorbent reactivity and capacity gradually decline during the cyclic process. Therefore, it is crucial to develop a better understanding on the role of the key parameters affecting the reactivity of the sorbent going through the cyclic carbonation/regeneration process. In this work, a systematic study on the sorbent preparation parameters (i.e., calcination temperature, calcination duration, calcination temperature ramp, potassium concentration, impregnation duration, drying temperature, re-calcination temperature, and re-calcination duration) was conducted to understand the effect of each parameter on the overall capacity and reactivity of the sorbent. The concentration of potassium additive (as carbonation reaction promoter) has the most significant effect on the reactivity of the sorbent and the optimum K/Mg molar ratio appears to be in the range of 0.1-0.16. The reactivity of the sorbent toward carbon dioxide at various operating conditions (i.e. temperature, CO2 concentration and steam concentration) was experimentally evaluated. The presence of steam significantly improves the reactivity of the sorbent which is attributed to formation of more favorable pore structure as well as the existence of a parallel carbonation reaction pathway involving the formation of a transient MgO.H2O* compound. The optimum carbonation reaction temperature in the presence of steam is around 380˚C. The effect of cycling on CO2 capture capacity of MgO-based sorbent was also experimentally investigated in this work. Series of carbonation/regeneration cycles (up to 25) have been carried out in a dispersed bed reactor to determine the effect of various variables on long term durability of the sorbent. The gradual loss of CO2 sorption capacity appears to be mainly due to loss potassium (a carbonation reaction promoter) in the cyclic process. Durability of the sorbents improves in the presence of steam, which is likely due to the favorable changes in the pore structure of the sorbents. A kinetic model was developed to fit the reactivity curves obtained from the dispersed bed tests at different operating conditions which was needed to predict the sorbent/catalyst performance in the regenerative process. Model parameters were defined and discussed for each of the operating conditions, as well as dispersed bed cyclic tests. Furthermore, the thermal behavior and the kinetics of partial decomposition of dolomite were studied in a dispersed-bed reactor to improve the reactivity of the sorbent. The microstructure and the nature of the solid products were found to be strongly dependent on the CO2 partial pressure near the reacting interface and on the decomposition temperature. A significant increase in the rate of the dolomite decomposition reaction was found in the presence of steam. Steam improves the kinetics of decomposition, modifies the radial distribution of the pores; and improves the connectivity of the pores inside the dolomite particles, which decreases the diffusion resistance of produced carbon dioxide inside the particle. A shrinking core model with variable product layer diffusivity was used to fit the experimental data and determine the kinetic parameters of the dolomite decomposition reaction. The results indicate that transport of CO2 across the reacting interface in the porous particle was the main limiting factor in the decomposition reaction at the experimental conditions investigated. A lab-scaled high-pressure/high-temperature packed-bed reactor was utilized to evaluate the performance of the sorbent in simultaneous water-gas shift reaction and sorbent carbonation environment. It was shown that the CO2 in the coal gas can be removed by regenerable MgO-based sorbents at temperatures around 350°C, and the CO2 removal can shift WGS reaction to enhance hydrogen production. Therefore, Sorbent Enhanced Water-Gas-Shift (SEWGS) can result in much higher hydrogen production without lowering the temperature, leading to higher overall process efficiency.
Ph.D. in Chemical Engineering, July 2015
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Title: INCORPORATING REACTIVE POWER MARKET INTO THE DAY-AHEAD ELECTRICITY MARKET
Creator: Al Ghamdi, Mohammed
Date: 2012-05-29, 2012-07
Description: The research work presented in this thesis proposes the incorporation of the reactive power market into the day-ahead electricity market in...
Show moreThe research work presented in this thesis proposes the incorporation of the reactive power market into the day-ahead electricity market in order to compensate generation companies (GENCOs) and independent power producers (IPPs) for providing any additional reactive power support, which varies on an hourly basis based on the load demand, transmission network configuration, and any contingencies that might occur. This proposal would minimize the total payment burden on the independent system operator (ISO), which is related to the reactive power dispatch. The proposed model achieves the main objective of an ISO in a competitive electricity market, which is to provide the required reactive power support from generators at minimum cost while ensuring the secure operation of the power system. In this research, the reactive power price is the bidding-based price that is submitted by the GENCOs and IPPs to the ISOs during the day-ahead market. The proposal takes into the account both the technical and economic aspects associated with the active power and reactive power dispatch in the context of the new operating paradigms in competitive electricity markets. In this research, the Security Constrained Unit Commitment (SCUC) based on AC power flow modeling is considered as the drive engine for clearing the day-ahead electricity market based on the amount of information provided by the market participants. This proposed framework would provide appropriate reactive power support from service providers at minimum cost, while ensuring the secure and reliable operation of the electrical power system. In the research, the PQ capability curves of the generating units are modeled to ensure the practically of the SCUC solutions that are obtained. This proposal would be an essential step toward a fair electricity market while increasing the security of the power system and reducing transmission congestions. Also, it would pave the road for various renewable energy resources since the penetration of renewable energy resources would impact the commitment of the generating units. This would impact the available reactive power reserve margin and security of the network. In addition, incorporating the reactive power market into the day-ahead market would provide a clear signal for optimal private investment in the reactive power capacity. The framework that has been developed is general in nature and can be used for any electricity market structure.
Ph.D. in Electrical Engineering, July 2012
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Title: INVESTIGATION OF NIOBIUM SURFACE STRUCTURE AND COMPOSITION FOR IMPROVEMENT OF SUPERCONDUCTING RADIO-FREQUENCY CAVITIES
Creator: Trenikhina, Yulia
Date: 2014, 2014-12
Description: Nano-scale investigation of intrinsic properties of niobium near-surface is a key to control performance of niobium superconducting radio...
Show moreNano-scale investigation of intrinsic properties of niobium near-surface is a key to control performance of niobium superconducting radio-frequency cavities. Mechanisms responsible for the performance limitations and their empirical remedies needs to be justified in order to reproducibly control fabrication of SRF cavities with desired characteristics. The high field Q-slope and mechanism behind its cure (120◦C mild vacuum bake) were investigated by comparison of the samples cut out of the cavities with high and low dissipation regions. Material evolution during mild field Q-slope nitrogen treatment was characterized using the coupon samples as well as samples cut out of nitrogen treated cavity. Evaluation of niobium near-surface state after some typical and novel cavity treatments was accomplished. Various TEM techniques, SEM, XPS, AES, XRD were used for the structural and chemical characterization of niobium near-surface. Combination of thermometry and structural temperature-dependent comparison of the cavity cutouts with different dissipation characteristics revealed precipitation of niobium hydrides to be the reason for medium and high field Q-slopes. Step-by-step effect of the nitrogen treatment processing on niobium surface was studied by analytical and structural characterization of the cavity cutout and niobium samples, which were subject to the treatment. Low concentration nitrogen doping is proposed to explain the benefit of nitrogen treatment. Chemical characterization of niobium samples before and after various surface processing (Electropolishing (EP), 800◦C bake, hydrofluoric acid (HF) rinsing) showed the differences that can help to reveal the microscopic effects behind these treatments as well as possible sources of surface contamination.
Ph.D. in Physics, December 2014
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Title: EXPLOITING NETWORK CODING IN DIFFERENT WIRELESS NETWORKS
Creator: Guo, Bin
Date: 2012-07-06, 2012-07
Description: Wireless communication networks have been incorporated into our daily life and provide convenience anytime and anywhere. However, the wireless...
Show moreWireless communication networks have been incorporated into our daily life and provide convenience anytime and anywhere. However, the wireless medium is unreliable and unpredictable. Current wireless networks suffer from low throughput, low reliability, etc. Network coding, an alternative approach, has attracted more interests and has emerged as an important technology in wireless networks. It can provide significant potential throughput improvements and a high degree of robustness. This dissertation is built on the theory of network coding. In this dissertation, different network coding protocols are designed in varied wireless networks. The first part of this dissertation proposes a novel coding-ware routing protocol in wireless mesh networks. In particular, a generalized coding condition is formally established to identify the coding opportunities. Based on general coding conditions analysis, a novel routing metric FORM (Free-ride Optimal Routing Metric) and the corresponding routing protocol are developed with the objective to exploit the coding opportunities and maximize the benefit of “free-ride” in order to reduce the total number of transmissions and consequently to increase the network throughput. The results show the proposed protocol achieves significant throughput gain than existing approaches. The second part of this dissertation exploits network coding in wireless cooperative networks. Firstly, a Decode-and-Forward Network Coded (DFNC) protocol is proposed for multi-user cooperative communication system. In particular, DFNC develops an efficient construction method for coding coefficients and a novel decoding algorithm that combines network coding and channel coding. DFNC exploits both temporal and spatial diversities through multiple channels by allowing all the users to generate redundant network-coded packets in a distributed manner and it helps fully explore the redundancy provided by network coding to realize error correction. Theoretical analysis and simulation results demonstrate that DFNC outperforms other transmission schemes in terms of Symbol Error Rate (SER) and achieves higher diversity order. Secondly, the idea of DFNC is extended and Modified-DFNC (M-DFNC) is introduced for a more practical scenario: not all the users will be able to dedicate their resources to provide assistance for others. The throughput analysis shows that M-DFNC outperforms the conventional cooperative protocol in the low-SNR regime and it implies that an adaptive cooperation system should be adopted to optimize the performance. The simulation results validate the theoretical analysis.
Ph.D. in Electrical Engineering, July 2012
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Title: SUSTAINABLE MULTILINGUAL COMMUNICATION: MANAGING MULTILINGUAL CONTENT USING FREE AND OPEN SOURCE CONTENT MANAGEMENT SYSTEMS
Creator: Kelsey, Todd
Date: 2011-05-03, 2011-05
Description: Multilingual content management systems, combined with streamlined processes and inexpensive organizational tools, make it possible for...
Show moreMultilingual content management systems, combined with streamlined processes and inexpensive organizational tools, make it possible for educators, non-profit entities and individuals with limited resources to develop sustainable and accessible multilingual Web sites. The research included a review of what’s been done in the theory and practice of designing Web sites for multilingual audiences. On the basis of that review, a series of sustainable multilingual Web sites were created, and a series of approaches and systems were tested, including MediaWiki, Plone, Drupal, Joomla, PHPMyFAQ, Blogger, Google Docs and Google Sites. There was also a case study on “Social CMS”, which refers to emergent social networks such as Facebook. The case studies are reported on, and conclude with high-level recommendations that form a roadmap for sustainable multilingual Web site development.
Ph.D. in Technical Communication, May 2011
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Title: THERMAL RESISTANCE OF SALMONELLA ENTERICA AND ESCHERICHIA COLI 0157:H7 IN PEANUT BUTTER
Creator: He, Yingshu
Date: 2014, 2014-05
Description: Salmonella enterica is a frequent food contaminant and the leading cause of foodborne bacterial illnesses in the United States. Our study...
Show moreSalmonella enterica is a frequent food contaminant and the leading cause of foodborne bacterial illnesses in the United States. Our study demonstrated that a 5-strain S. enterica cocktail displayed increased heat resistance in peanut butter of low water activity (aw). Significant differences (P < 0.05) were found between the survival rates of Salmonella enterica and Escherichia coli O157:H7 in peanut butter with different formulations and water activity. High carbohydrate content in peanut butter and low incubation temperature resulted in higher levels of bacterial survival during storage but lower levels of bacterial resistance to heat treatment. Furthermore, we also compared the relative heat resistance of three individual strains of S. enterica representing serotypes Typhimurium, Enteritidis and Tennessee and the 3-strain cocktail treated at both 90oC and 126oC in two different peanut butter formulations with varied fat and carbohydrate contents and adjusted water activities (aw from 0.2 to 0.8). When treated at 90oC, increased water activity in peanut butter significantly (P < 0.05) reduced the heat resistance of desiccation-stressed S. enterica cells. Differences in heat resistance were also detected among the three S. enterica serotypes and between the two peanut butter formulations. When treated at 126oC, the differences in bacterial heat resistance among serotypes and adjusted water activities were less notable (P > 0.05). Based on the Weibull model, an average of 52 to 132 min was required to achieve a 5-log reduction of the 3-strain cocktail at 90oC in peanut butter with an aw of 0.2. When aw was increased to 0.6, to achieve the same 5-log reduction required only 23-27 min. At aw of 0.8, S. enterica could be completely killed in less than 10 min in peanut butter with a fat content of 48.49%. Using scanning electron microscopy, we observed minor morphological changes xiii of S. enterica cells during desiccation and rehydration processes in peanut oil, which was used as a surrogate for peanut putter. Results from this study collectively suggest that water activity plays a critical role in determining S. enterica heat resistance in peanut butter. The variability that exists among the heat resistance of different S. enterica serotypes in different peanut butter formulations should also be taken into consideration for developing and validating effective intervention and mitigation strategies in peanut butter production.
PH.D in Biology, May 2014
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Title: LONG-TERM AEROBIC AND ANAEROBIC TRANSFORMATIONS OF ORGANIC MATTER IN ANAEROBICALLY DIGESTED BIOSOLIDS
Creator: Lukicheva, Irina
Date: 2012-12-05, 2012-12
Description: Long-term anaerobic storage of biosolids in a lagoons type of system as a post-treatment to anaerobic digestion is a proven process for...
Show moreLong-term anaerobic storage of biosolids in a lagoons type of system as a post-treatment to anaerobic digestion is a proven process for further pathogen reduction to produce Class A biosolids. At the same time, final biosolids product could develop odors during storage and handling, limiting the flexibility of biosolids utilization. The goal of this research was to study properties of biosolids under different lengths of aging time to determine the stability of final product for its odor potential. Field lagoons of Metropolitan Water Reclamation District of Greater Chicago were sampled to estimate the spatial and temporal variations in the physical-chemical properties and biological stability indicators, namely, total solids, volatile solids, pH, electric conductivity, total Kjeldahl nitrogen, ammonia-N, nitrite/nitrate-N, accumulated oxygen uptake for the 20-hour respirometric test, soluble protein concentration and headspace concentrations of volatile sulfur compounds. The sampling campaign was performed in October 2009. Two types of lagoons were assessed in this study- high-solids lagoons that are loaded with sludge that was previously anaerobically digested and dewatered on the centrifuges, and low-solids lagoons that are loaded with sludge that was previously digested but not dewatered. The analysis of collected data suggested that for the high-solids lagoons the surface layer biosolids (depth of above 0.15 m) undergo long-term aerobic oxidation resulting in higher degree of final product stabilization. The subsurface layers (depth below 0.15 m) are subjected to anaerobic environment where the conditions allow only the initial rapid organic matter degradation approximately within the first year, followed xii by very slow degradation. In addition, microbiological analyses using Fluorescent in situ Hybridization did not indicate active microbial communities in aged biosolids. The performance of low-solids lagoons in the reduction of the biodegradability parameters was shown to be similar to that of the high-solids lagoons. Low-solids lagoons were shown to perform the dewatering function reducing moisture in the digested sludge from initial 2-3% TS to up to 16% TS. Although the lagoon aged biosolids were found to be stable in comparison with other products, such as composts, further aerobic processes taking place after lagoons, such as air-drying and stock-piling could induce further active biological activity. This could potentially result in the odor formation from the air-dried final product. For these reasons, more research is required on the mechanisms promoting further product degradation after lagoons aging.
PH.D in Environmental Engineering, December 2012
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Title: ADVANCING DESIGN SIZING AND PERFORMANCE OPTIMIZATION METHODS FOR BUILDING INTEGRATED THERMAL AND ELECTRICAL ENERGY GENERATION SYSTEMS
Creator: Zakrzewski, Thomas
Date: 2017, 2017-07
Description: Combined electrical and thermal energy systems (i.e., cogeneration systems) will play an integral role in future energy supplies because they...
Show moreCombined electrical and thermal energy systems (i.e., cogeneration systems) will play an integral role in future energy supplies because they can yield higher overall system fuel utilization and efficiency, and thus produce fewer greenhouse gas emissions, than traditionally separate systems. However, methods for both design sizing and performance optimization for cogeneration systems and commercial buildings lag behind the tremendous advancements that have been made in building performance simulation methods. Therefore, the overall goal of this research is to develop and apply novel cogeneration system modeling techniques for optimizing design sizing and dispatch of generation sets that reduce energy use, energy costs, and greenhouse gas emissions. This research is divided into four main research objectives: (1) generalizing cogeneration performance of lean burn natural gas spark ignition reciprocating engines, (2) developing a new Design and Optimization of Combined Heat and Power (DOCHP) systems optimization tool for improving design-sizing of building-integrated and grid-tied CHP systems, (3) demonstrating the utility of the DOCHP tool with several practical applications, and (4) integrating on-site intermittent renewable energy systems into the DOCHP tool to analyze micro-grid applications. This research leverages recent developments in multiple areas of building and system simulation methods. DOCHP advances design sizing and performance optimization methods for building integrated thermal and electrical energy generation systems through the application of an evolutionary artificial intelligence-based genetic algorithm and its ability to resolve to non-linear optimization with discrete constraints while considering non-linear part-load generation set performance curves.
Ph.D. in Civil Engineering, July 2017
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Title: DEVELOPMENT OF AN IMPLICITLY COUPLED ELECTROMECHANICAL AND ELECTROMAGNETIC TRANSIENTS SIMULATOR FOR POWER SYSTEMS
Creator: Abhyankar, Shrirang
Date: 2011-11, 2011-11
Description: The simulation of electrical power system dynamic behavior is done using tran- sient stability simulators (TS) and electromagnetic transient...
Show moreThe simulation of electrical power system dynamic behavior is done using tran- sient stability simulators (TS) and electromagnetic transient simulators (EMT). A Transient Stability simulator, running at large time steps, is used for studying rela- tively slower dynamics e.g. electromechanical interactions among generators and can be used for simulating large-scale power systems. In contrast, an electromagnetic transient simulator models the same components in finer detail and uses a smaller time step for studying fast dynamics e.g. electromagnetic interactions among power electronics devices. Simulating large-scale power systems with an electromagnetic transient simulator is computationally inefficient due to the small time step size in- volved. A hybrid simulator attempts to interface the TS and EMT simulators which are running at different time steps. By modeling the bulk of the large-scale power system in a transient stability simulator and a small portion of the system in an electromagnetic transient simulator, the fast dynamics of the smaller area could be studied in detail, while providing a global picture of the slower dynamics for the rest of power system. In the existing hybrid simulation interaction protocols, the two simulators run independently, exchanging solutions at regular intervals. However, the exchanged data is accepted without any evaluation, so errors may be introduced. While such an explicit approach may be a good strategy for systems in steady state or having slow variations, it is not an optimal or robust strategy if the voltages and currents are varying rapidly, like in the case of a voltage collapse scenario. This research work proposes an implicitly coupled solution approach for the combined transient stability and electromagnetic transient simulation. To combine the two sets of equations with their different time steps, and ensure that the TS and EMT solutions are consistent, the equations for TS and coupled-in-time EMT equations are solved simultaneously. While computing a single time step of the TS equations, a simultaneous calculation of several time steps of the EMT equations is proposed. Along with the implicitly coupled solution approach, this research work also proposes to use a three phase representation of the TS network instead of using a positive-sequence balanced representation as done in the existing transient stability simulators. Furthermore a parallel implementation of the three phase transient stability simulator and the implicitly coupled electromechanical and electromagnetic transients simulator, using the high performance computing library PETSc, is presented. Re- sults of experimentation with different reordering strategies, linear solution schemes, and preconditioners are discussed for both sequential and parallel implementation.
Ph.D. in Electrical Engineering, December 2011
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Title: IMPROVED SPATIAL-TEMPORAL RECONSTRUCTION FOR CARDIAC AND RESPIRATORY GATED SPECT
Creator: Qi, Wenyuan
Date: 2014, 2014-12
Description: Myocardial perfusion single photon emission computed tomography (SPECT) is an important imaging technique for evaluating coronary artery...
Show moreMyocardial perfusion single photon emission computed tomography (SPECT) is an important imaging technique for evaluating coronary artery disease. It can provide information of both myocardial perfusion and ventricular function. However, SPECT images su er from both cardiac and respiratory motion blur. In order to reduce the motion degrading, cardiac and respiratory gated SPECT imaging is used. In gated SPECT imaging, due to the lowered counts, the gated images will be more noisy than the ungated ones. Spatiotemporal (4D) processing is often used to reduce the noise level in gated images. In this thesis, we aim to investigate spatial and temporal processing techniques for improving the quality in cardiac and respiratory gated SPECT imaging. First, we will investigate a piecewise spatial smoothing prior based on totalvariation (TV) in 4D cardiac SPECT image reconstruction. In previous studies, it was found that spatial smoothing could adversely a ect the accuracy of 4D reconstruction in cardiac gated SPECT when temporal smoothing was applied, even though it could suppress the noise level. Our goal is to explore whether a piecewise spatial smoothing prior will improve the image accuracy while reducing the noise. Toward this goal, we will compare TV based piecewise spatial smoothing with quadratic spatial smoothing with simulated imaging, in which we will evaluate the lesion detectability. Clinical data will also be used to compare the results as a preliminary test. Motion-compensated temporal smoothing is known to play a key role in 4D cardiac gated SPECT reconstruction. Next, we will investigate whether better motion estimation could further improve the accuracy of reconstructed images. We will consider two di erent motion estimation models and the known motion in simulated experiments. The motion estimation methods are the classic optical ow estimation (OFE) and a periodic motion estimation method. We will evaluate the reconstruction from di erent motion models using several numerical quanti cation metrics. Furthermore, we will demonstrate reconstruction with the two motion estimation models using clinical acquisitions. Respiratory motion is known to cause motion blur in SPECT image reconstruction, and respiratory gated SPECT imaging can be e ective to combat its e ect. We will develop reconstruction techniques in respiratory gated SPECT. We will consider two reconstruction schemes for respiratory gated SPECT. The rst scheme is a post motion compensated reconstruction, in which images at di erent respiratory phases are reconstructed seperately, and afterwards are averaged over all the respiratory gates by motion compensation. The second scheme is a model based motion compensated reconstruction approach, in which one reference gate is used to describe the acquisition data of all the respiratory gates. Due to irregular respiratory motion, the data acquisition in each respiratory gate is not uniformly distributed among the acquisition angles, which would lead to limited-angle artifacts. To correct such artifacts, we propose an angle compensation method in the reconstruction. In order to deal with both cardiac and respiratory motion, we will investigate a 4D reconstruction approach for dual cardiac-respiratory gated SPECT reconstruction. This approach can accommodate the acquired data simultaneously from di erent cardiac and respiratory gates. It can exploit the correlation in the signal component among both the cardiac and respiratory phases. Both simulated experiments and clinical reconstruction will be used for evaluating this reconstruction approach. Due to the radiation risk of myocardial perfusion imaging (MPI) scans, there is an urgent need to lower the radiation dose used in SPECT. However, lower radiation dose will lead to more noisy reconstruction, which is even more serious in gated SPECT. We would explore the potential of using 4D reconstruction for lowering the dose in dual cardiac-respiratory gated SPECT.
Ph.D. in Electrical and Computer Engineering, December 2014
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Title: ROLE OF EXTRACELLULAR MATRIX IN CELLULAR BEHAVIOR AND TISSUE FUNCTION
Creator: Sridharan, Indumathi
Date: 2012-04-22, 2012-05
Description: Matrix-dictated control of stem cell differentiation and tissue status are of considerable interest to cell biologists and tissue engineers....
Show moreMatrix-dictated control of stem cell differentiation and tissue status are of considerable interest to cell biologists and tissue engineers. To create suitable biological scaffolds for tissue engineering and cell therapeutics, it is essential to understand the matrix mediated specification of cell lineage. Our study examines the role of matrix properties on cellular behavior and tissue mechanics. To this end, we studied the effect of collagen type I on stem cell differentiation and its mechanical properties within a live tissue. We altered the properties of collagen type 1 by incorporating CNT. The collagen-carbon nanotube (collagen-CNT) composite material was stiffer with thicker fibers and longer D-period. We find that the enhanced mechanical and structural properties of collagen-CNT allow for rapid and efficient derivation of neural progenitors from human decidua parietalis placental stem cells (hdpPSC). Both structure and stiffness of the matrix are important determinants of neural differentiation rate. Strikingly, the collagen-CNT matrix, unlike collagen, imposes the neural fate by an alternate mechanism that is independent of beta-1 integrin and beta-catenin. The study demonstrates the sensitivity of stem cells to subtle changes in the matrix and the utilization of a novel biocomposite material for efficient and directed differentiation of stem cells. Investigation of connective tissue disorders has led to the understanding of the important role played by collagen. So far, native collagen fibers within an intact tissue have not been examined. In this study, we employed a unique approach- histochemical staining guided high-resolution elasticity mapping- to study collagen and smooth muscle in fresh vaginal wall connective tissue. The comparative study of tissues collected from healthy pre-menopausal (pre-M) and post-menopausal (post-M) women suggest that during menopause, collagen’s structure and elasticity are subtly altered. The systematic analysis enables detection of minute changes in collagen in non-fatal conditions such as pelvic organ prolapse and other genitor-urinary disorders, where the initial symptoms are subtle and multivariate and where early diagnosis will allow non-invasive interventions and reduce incidence of surgical correction for these common disorders.
Ph.D. in Molecular Biochemistry and Biophysics, May 2012
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Title: THE EXAMINATION OF EFFORT TESTS: IDENTIFYING AN EFFICIENT APPROACH TO THE ASSESSMENT OF MALINGERING
Creator: Van De Kreeke, Diana
Date: 2013, 2013-05
Description: Malingering is an important issue in neuropsychology. A person can malinger both cognitive and psychological symptoms and it is important for...
Show moreMalingering is an important issue in neuropsychology. A person can malinger both cognitive and psychological symptoms and it is important for a clinician to assess for this possibility as malingering invalidates test findings. Several embedded and standalone effort tests exist for the purpose of malingering classification. This study looked to assess the effectiveness of embedded cognitive effort measures as compared to standalone effort measures. Additionally, the effectiveness of a smaller set of measures versus a larger set was analyzed for both cognitive and psychological measures. The likelihood of a person malingering both cognitive and psychological symptoms was assessed. Lastly, exploratory analyses were conducted to assess for differences between malingerers and non-malingerers. It was discovered that the California Verbal Learning Test-Second Edition-Forced Choice and the Victoria Symptom Validity Test were poor estimators of malingering classification. Therefore, the cognitive effort measures included in the analyses were the Reliable Digit Span, Rey 15-Item Test, Word Memory Test, and the Test of Memory Malingering. Psychological measures included the F and FBS indices from the Minnesota Multiphasic Personality Inventory-2 and the Negative Impression Management and Malingering Index scales from the Personality Assessment Inventory. Findings revealed that stand-alone tests add a significant amount of variance to malingering classification over and above embedded measures in a cognitive test battery. The most effective set of cognitive effort tests included the Reliable Digit Span, Rey 15-Item Test, and Word Memory Test. The Test of Memory Malingering did not add significant additional variance to the classification of malingering. Results showed that a vii person is not likely to malinger both cognitive and psychological symptoms. Lastly, the F and Negative Impression Management indices were just as effective at classifying malingering as when the FBS and Malingering Index scales were also used. Future research should further assess the actual sensitivities of the California Verbal Learning Test-Second Edition-Forced Choice and the Victoria Symptom Validity Test. Also, research should assess whether different cut off scores for the Test of Memory Malingering lead to increased efficiency of the measure for malingering classification.
PH.D in Psychology, May 2013
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Title: Load Redistribution Attacks and Protection Strategy Design in Electric Power Systems
Creator: Yuan, Yanling
Date: 2012-04-27, 2012-05
Description: Electric power systems have evolved over the past century to the largest and the most complex cyber-physical systems. With the development of...
Show moreElectric power systems have evolved over the past century to the largest and the most complex cyber-physical systems. With the development of Smart Grid, cyber security has become an area of growing concern. False data injection attack has recently attracted wide research interest. This thesis develops the concept of load redistribution attack, a special type of false data injection attack. The physical and economic impact of load redistribution (LR) attacks is quantitatively analyzed in this thesis. Since LR attacks can successfully bypass bad data detection and manipulate the state estimation outcome, security constrained economic dispatch (SCED) based on the false state estimation would lead the system into a non-optimal or insecure operation state. Based on the consequence analysis, two different attacking goals are differentiated from the adversary’s perspective, i.e., immediate attacking goal and delayed attacking goal. For the immediate attacking goal, a max-min attacker-defender model is proposed to identify the most damaging immediate LR attack. Two different algorithms are used to solve this bi-level optimization problem. For the delayed attacking goal, a tri-level model is proposed to identity the most damaging delayed LR attack. This thesis studies the economic impact of LR attacks on power market operation. A convex model is proposed under the mechanism of virtual bidding to compute the optimal injection of LR attack, which gains the most profit from the attackers’ perspective. The quantitative analysis of LR attacks provides an in-depth insight on effective attack prevention with limited protection resource budget. This thesis proposes a new protection strategy, which intends to mitigate the most damaging effect of LR attacks on power system operation. The criterion of determining effective protections against the most damaging LR attack, considering the existence of stochastic measurement errors, is deduced.
Ph.D. in Electrical Engineering, May 2012
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Title: IRON INCORPORATION INTO FERROELECTRIC LEAD TITANATE
Creator: Ganegoda, Hasitha
Date: 2012-11-27, 2012-12
Description: Incorporation of iron into ferroelectric lead titanate with ABO3 perovskite structure is widely utilized to fabricate materials with...
Show moreIncorporation of iron into ferroelectric lead titanate with ABO3 perovskite structure is widely utilized to fabricate materials with ferroelectric and ferromagnetic order. These solid solutions exhibit room temperature ferromagnetic properties at iron concentration as low as 1 mole%. Iron (Fe3+) is highly compatible with titanium (Ti4+) in ionic radii and obviously incompatible in the valence state. Magnetoelectric coupling has been observed in 50 mole% Fe substituted lead titanate. The molecular mixing of precursor materials in wet chemical synthesis such as sol-gel has advantage over conventional solid state sintering in achieving higher solubility of the substituent. A series of Pb(FexTi1−x)O3− solid solution in the composition range x = 0 to 1 has been synthesized using sol-get route, followed by a moderate temperature (700 C) calcination. The structure and properties of samples were characterized using x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), dielectric spectroscopy, Raman spectroscopy, and magnetic measurements. SEM results indicated a gradual change in sample morphology, changing from individual particles to nano-aggregates with Fe concentration. EDX confirmed uniform distribution of dopants when Fe concentration x 0.3 and Fe concentration close to nominal composition with possibility of lead loss. XRD results indicated a rapid reduction of tetragonal distortion upon Fe substitution, Fe solubility limit of 10 mole%, and PbFe12O19 impurity phase formation at compositions x 0.4. XAS clearly indicated that Ti prefers a 6 coordinated distorted oxygen octahedra and Fe is surrounded by 5 oxygens situated at a similar distance. Other measurements suggested that ferroelectric and ferromagnetic ordering may arise in Ti-rich and Fe-rich phases, respectively. None of the samples below x = 0.2 was found to be ferromagnetic at room temperature.
PH.D in Physics, December 2012
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Title: SOCIAL FUNCTIONING AND CORE SYMPTOMATOLOGY AS PREDICTORS OF RESPONSE TO A SUMMER TREATMENT PROGRAM FOR YOUTH WITH COMBINED TYPE ATTENTION DEFICIT HYPERACTIVITY DISORDER
Creator: Uribe, Roberto Alejandro
Date: 2015, 2015-12
Description: The study was a retrospective repeated measures analysis of 108 youth (age 6-12) who took part in the 2008-2012 Camp STAR (Summer Treatment...
Show moreThe study was a retrospective repeated measures analysis of 108 youth (age 6-12) who took part in the 2008-2012 Camp STAR (Summer Treatment Program for ADHD and Related Disorders) Summer Treatment Program. Developed by William E. Pelham in 1980, the Summer Treatment Program (STP) is an intensive psychosocial intervention delivered to children ages 6-12 in natural settings through the medium of summer camp. A recognized evidence base for the STP has steadily developed and evolved leading to improved stabilization of ADHD associated issues and treatment satisfaction. The following investigation sought to address questions about the efficacy of the STP with respect to predicting treatment responses for a subgroup of ADHD youth presenting with complex clinical presentations of combined type ADHD. The study built on prior evaluations of predictor importance by utilizing socio-emotional measures from the daily behavioral data of the STP, as well as more typically used ADHD dimensional symptom severity measures to inform treatment fit. As anticipated, because the heterogeneity of the disorder suggests that response to treatment is multifaceted, no combination of predictor variables produced a regression equation model that significantly explained variance across all of the treatment outcome variables. After controlling for concurrent pharmacotherapy and age, the combined effects of pretreatment core ADHD symptom severity and social functioning measures were found to significantly explain variance in a criterion variable corresponding with camp objectives (e.g., developing social competencies and coping skills, decreased functioning; Overall STP Improvement Index), as well as positive and negative socio-emotional behaviors measured directly by the STP Point System at the end of the camp. Change in R2 statistics confirmed the study hypothesis in which, the pretreatment socio-emotional factor sets significantly improved the prediction of multiple treatment outcomes over and above DSM-IV ADHD symptom dimensions and control variables. Ten percent of unique variance when predicting informant ratings of improvement made while at camp, 4% unique variance when predicting positive social behavior at the conclusion of Camp STAR, and 2% unique variance when predicting negative social behavior at the conclusion of Camp STAR were among the results. Observed negative behaviors at baseline demonstrated predictive utility whereas results pertaining to hyperactivity/impulsivity and inattention symptom dimensions did not significantly influence behavior, and subsequently, revealed little about the observed variation in outcomes in this particular dataset. While each of the core DSM-IV symptom dimensions are known to be differently associated with a variety of domain specific impairments in the general population (Lahey, & Willcutt, 2010), the results from this study suggest that with ADHD subgroups featuring severe symptom and impairment profiles, the core symptom dimensions did not appear to be as differentially associated with functional impairment. In cases of severe combined type ADHD, decisions about treatment fit should be based more on the socio-emotional impact of symptoms rather than their mere presence. The findings underscore the value in identifying socio-emotional impairments for individuals diagnosed with severe and complicated ADHD as early as possible and to intervene with intensive modalities specifically aimed at developing skills and cognitive faculties that enhance abilities to maintain healthy relationships.
Ph.D. in Psychology, December 2015
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Title: MODELING THE PERFORMANCE OF A SOLAR CHIMNEY WITH BUILT-IN PHASE CHANGE MATERIALS TO IMPROVE NATURAL VENTILATION
Creator: Khorraminejad, Aysan
Date: 2014, 2014-12
Description: The use of solar chimneys to improve natural ventilation in buildings has been shown to yield energy savings while maintaining thermal comfort...
Show moreThe use of solar chimneys to improve natural ventilation in buildings has been shown to yield energy savings while maintaining thermal comfort in some climate zones. However, one disadvantage is that the ability to control passive ventilation with solar chimneys is often limited by temporal variations of building function and diurnal weather patterns. The unique thermal properties of phase change materials (PCMs) may provide opportunities to manage some of the limitations of solar chimney strategies in buildings through the timed storage and release of thermal energy, which can aid in minimizing daytime heat gains and increasing the effectiveness of nighttime flushing by natural ventilation. This work explores the potential of PCMs combined with solar chimneys to support the passive ventilation of buildings using whole building energy simulation. Results are intended to inform architects and engineers on best practices for incorporating PCMs in buildings with solar chimneys. A model of a prototype office building designed to ASHRAE Standard 90.1 was developed in EnergyPlus and investigated in five U.S. climate zones. A total of 1023 energy simulations were performed to address the following research questions: (1) In what U.S. climate zone is the use of PCMs most appropriate? (2) Can PCMs improve night flushing ventilation when used with a solar chimney? (3) What are the optimal locations for installation of PCMs in building and solar chimney construction in order to provide optimal cooling load reductions? and (4) How do PCM properties influence cooling load reductions? Results demonstrate that the solidification and melting process of PCMs can indeed be used to prolong natural ventilation for night flushing in the evening and nighttime, particularly in climate zones with large diurnal outdoor temperature fluctuations. Results also suggest the following: (1) the optimal location for installation of PCMs in most climates is within the structure of south-facing envelope assemblies; (2) the PCM melting temperature should be equal to or greater than the zone set point temperature; (3) thicker PCMs can yield slightly more cooling energy savings than thinner PCMs; and (4) the thermal conductivity of PCMs does not appear to have a substantial influence on performance.
Ph.D. in Architecture, December 2014
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Title: FUNCTION APPROXIMATION WITH KERNEL METHODS
Creator: Zhou, Xuan
Date: 2015, 2015-12
Description: This dissertation studies the problem of approximating functions of d variables in a separable Banach space Fd. In particular we are...
Show moreThis dissertation studies the problem of approximating functions of d variables in a separable Banach space Fd. In particular we are interested in convergence and tractability results in the worst case setting and in the average case setting. The symmetric positive definite kernel in both settings is of a product form Kd(x, t) := d =1 1 − α2 + α2 Kγ (x , t ) for all x, t ∈ Rd. The kernel Kd generalizes the anisotropic Gaussian kernel, whose tractability properties have been established in the literature. For a fixed d, we study rates of convergence, which indicate how quickly approximation errors decay. Since rates of convergence can deteriorate quickly as d increases, it is desirable to have dimension-independent convergence rates, which corresponds to the concept of strong polynomial tractability. We present sufficient conditions on {α }∞ =1 and {γ }∞ =1 under which strong polynomial tractability holds for function approximation problems in Fd. Numerical examples are presented to support the theory and guaranteed automatic algorithms are provided to solve the function approximation problem in a straightforward and efficient way. viii
Ph.D. in Applied Mathematics, December 2015
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Title: A NOVEL METHOD FOR THE IMPLEMENTATION OF STRUCTURAL CONTACT IN FINITE ELEMENT METHODS OFFERING SIMPLIFIED TREATMENT OF ENERGY DISSIPATION
Creator: Grudzinski, James John
Date: 2012-04-24, 2012-05
Description: A novel method for implementing contact/impact in an implicit nite element formulation is presented. The method uses the ideas of buoyancy to...
Show moreA novel method for implementing contact/impact in an implicit nite element formulation is presented. The method uses the ideas of buoyancy to enforce the normal contact constraint and a velocity dependent force to model energy dissipation. Upon contact (penetration) a normal force equal to the depth of penetration times a target weight density (di erent and much larger than the actual material weight density) creates a normal pressure on the contacting body. In addition to the buoyancy force, the penetrating surface area is subjected to a drag-like force that acts in a direction opposite the velocity vector of the penetrating node of the contacting body . This rate dependence is broken up into components tangential and normal to the target surface. The normal component of the drag performs two functions. First it provides for an energy absorbing mechanism similar to a coe cient of restitution for modeling non-conservative systems. Secondly, it can provide damping (analogous to mathematical damping) which can aid in solution convergence. The tangential component of the damping force serves the function of modeling friction in a simpli ed manner. The method applies contact forces in the manner of external forces and as such lends itself well to simpli ed contact detection schemes which rely on functional representation of bodies. The method is described and demonstrated through several examples including a comparison to experimental data.
Ph.D. in Mechanical and Aerospace Engineering, May 2012
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Title: THE PALAIS GARNIER: TOWARD AN ARCHITECTURE OF DANCE AND MUSIC IN XIX CENTURY FRANCE
Creator: Vranas Olsen, Cynthia
Date: 2017, 2017-05
Description: As a doctoral candidate, this writer has focused on the Romantic Movement of 19th century France, where the arts mutually influenced each...
Show moreAs a doctoral candidate, this writer has focused on the Romantic Movement of 19th century France, where the arts mutually influenced each other, just as in ancient Greece and Rome. This research highlights the interrelationships of the Arts to Architecture by examining artists such as Hugo in drama, Gautier in literature, Delacroix in painting, Chopin and Adam in music, Noverre in dance and Garnier in architecture. Although Noverre’s specialty was dance, he believed that theater buildings were first monuments to the arts. For Garnier, 100 years later, the Arts and Architecture were not separate identities. They complemented and enhanced one another. Both books, Observations sur la Construction d’une Nouvelle Salle de l’Opera by Jean-Georges Noverre and Le Theatre by Charles Garnier, were publications translated extensively from French to the English language as primary sources. In designing a theater building, the architect is responsible for synthesizing and translating myriad information in order to create an appropriate and responsive language. An invaluable knowledge of technical considerations - set design, lighting, backstage equipment, sightlines, acoustics and facilities for performers - is critical, as is balancing the client’s concerns and the user/spectator’s needs. As performance expresses a cultural instinct for communicative involvement, this writer believes that a theater building, itself, is a reflection of the arts. It is art, therefore, that inextricably shapes the programs and designs of our theater buildings. The Palais Garnier, completed in 1875 for the Paris Opéra and its associated Paris Opéra Ballet, is thought to mirror the cultural complexity of the age. Before this time, the Paris Opéra was housed in the Salle Le Peletier, a temporary building with inadequate facilities that did not reflect the existing, lavish, highly skilled art that was performed. Garnier’s travels to ancient sites in Greece and Rome resulted in his classic book, Le Théatre. By writing, he immersed himself in the study of the physical qualities of the theater, and it eventually became his architecture. The form and character of the theater buildings studied reflect the changing social structures, technology and patronage that sponsored them. The Palais Garnier reflects a unique intersection of the arts, along with the political, social and economic influences of that time. Musicians turned their attention toward the expressions of intense feelings that were influenced by poetry and the visual arts. The Palais Garnier, with its grandeur and opulence, became its own “performance”. The multi-disciplinary nature of architecture and the study of the interrelationships of the arts can inform creativity. Just like the timeless, majestic Palais Garnier in Paris, in 19th century France, new architectural structures can become their own profound monumental and memorable “performances” for future generations.
Ph.D. in Architecture, May 2017
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Title: ENABLING TOOLS FOR SINGLE CELL ANALYSIS
Creator: Li, Zhaoxia
Date: 2011-07, 2011-07
Description: Cells are basic functional units of life. A cell function is mediated by proteins and genes, whose distribution and expression level depends...
Show moreCells are basic functional units of life. A cell function is mediated by proteins and genes, whose distribution and expression level depends remarkably on the microenvironment. In the native environment, individual cells behave differently but communicate with surrounding cells. It is imperative to investigate proteins and genes at the single cell level in their native environment. The current representative single cell analysis methods, fluorescent techniques, are the most direct tools to study a single cell. The commonly used methods to measure protein and gene expression levels in single cells are on the basis of fluorescence labeling, such as fluorescence-activated cell sorting and live cell microscopy. They become more powerful when combine with the use of microfluidic devices. The disadvantages of these methods are, (1) their limited sensitivity doesn’t allow the detection of low-abundance proteins and genes; (2) they are unable to detect the cell-to-cell difference within a population; (3) the cell-sorting based method is lack of spatial resolution since the isolation of cells from the natural environment is required for analysis. To tackle these challenges, we established atomic force microscopy based approaches for in-situ gene and protein analysis on a target single live cell. The methods provide the spatial and quantitative information of cells in their native culture environment. They are effective and sensitive to detect low-abundant proteins and genes. In this thesis work, we developed a novel immunofluorescence assisted affinity mapping (IF-AM) method, in which immunofluorescence provides the guidance to locate a desired type of cell in a cell community for performing affinity mapping to quantify the local protein density at a high spatial resolution. Due to the ability of directly assessing proteins of individual cells, the IF-AM method is shown to be a sensitive tool for xiii resolving subtle differences in the local expression of membrane proteins even at low abundance. In the following work, we improved the accuracy of protein quantification by adapting the separation work based calculation rather than the previously used maximum adhesion force based calculation, and established a practical model to analyze the data systematically. We applied the methods to investigate the membrane proteins TRA-1-81 and E-cadherin on human embryonic stem cells. The heterogeneous distribution of TRA- 1-81 and the homogeneous distribution of E-cadherin as well as the quantitative measurement of the protein local abundance provided comprehensive information in understanding the strategy of hES cells to maintain the stemness during cell proliferation and to initiate the differentiation. An mRNA retrieval method was also developed to perform the gene expression analysis on a single cell of a desired type in a cell community. This was achieved by using a functionalized AFM tip as a bait to bind and retrieve mRNA from a desired single cell, followed by sensitive Quantitative Polymerase Chain Reaction (Q-PCR) analysis. The extraction of mRNA from live cells was performed with non/negligible damage to the cells. The established method here enabled the gene expression analysis of individual live cells at the original sites without disrupting the cell context. Thus the gene expression of a target cell and its surrounding cells can be analyzed in parallel, deriving concrete data for understanding the behavior of one cell in concert with that of the surrounding cells in the same or different cell population. The method was successfully applied in the study of side population cells in ovarian cancer cells. The methods developed in this thesis are versatile, and can be broadly applied to the study of different membrane proteins and genes of various cell types.
Ph.D. in Chemistry, July 2011
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