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Title: ANISOTROPIC MICROSRHEOLOGY OF SELF-ASSEMBLING COLLAGEN NETWORKS
Creator: Dutov, Pavel
Date: 2015, 2015-05
Description: Collagen is the main component of human connective tissue and extracellular matrix. Here we report multiple novel methods for utilizing...
Show moreCollagen is the main component of human connective tissue and extracellular matrix. Here we report multiple novel methods for utilizing optical tweezers to measure mechanical properties of different hierarchical levels of collagenous materials. First, we introduce a method for optical trap calibration that is suitable for viscoelastic material. The method is designed for use on experimental setups with two optical tweezers and is based on pulling a trapped particle with one trap while holding it with the other. The method combines advantages of commonly known PSD-fitting and fast-sweeping methods, allowing calibration of a completely fixed trap in a fluid of unknown viscosity/viscoelasticity without additional expensive equipment. Then we report an approach to measure the longitudinal component of the elastic moduli of biological fibers under conditions close to those found in vivo and apply it to type I collagen from rat tail tendon. This approach combines optical tweezers, atomic force microscopy, and exploits Euler-Bernoulli elasticity theory for data analysis. The approach also avoids the traditional drying-soaking cycle, since samples are freshly extracted. Importantly, strains are kept below 0.5%, which appear consistent with the linear elastic regime. We find, surprisingly, that the longitudinal elastic modulus of type I collagen cannot be represented by a single quantity but rather is a distribution that is broader than the uncertainty of our experimental technique. Lastly, we report a new method for characterizing anisotropic viscoelastic response of collagenous matrices. Anisotropic collagenous extracellular matrices are used in biomedicine to enhance the wound healing process by directing fibroblast proliferation. We utilize an optical trap to monitor the thermal fluctuations of microspheres embedded into collagenous network to extract a viscoelastic response function of the network along the principal axes of anisotropy.
Ph.D. in Chemical Engineering, May 2015
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Title: TOWARD THE AUTOMATIC ORGANIZATION AND COMPREHENSION OF SOCIAL NETWORK COMMUNICATION
Creator: Platt, Alana
Date: 2013, 2013-05
Description: Social networking sites are radically transforming the way we communicate and relate to each other. They facilitate timely information...
Show moreSocial networking sites are radically transforming the way we communicate and relate to each other. They facilitate timely information exchange and give us unprecedented access to numerous sources of information on a myriad of topics. Although the information is available, there are a number of challenges that inhibit utilization of this information: Social Networks have a great volume of messages that the user must sift through to find relevant ones, messages are frequently repetitive, the information is not organized topically, and there is little context information. The information consumer (user) must take on many of the tasks traditionally performed by the information producer to get a “big picture” understanding of the topic. This thesis introduces a framework for an automated information gathering and organization system to facilitate the information consumer’s comprehension of a given topic. The framework addresses two primary components: the user interface for the system and identification of sub-topics. The framework was implemented as a research platform designed to bring these two components together and support future research in the domain.
PH.D in Computer Science, May 2013
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Title: Structural Survey of Select Spectrin Type Repeats within the Rod Region of Dystrophin Using Hydrophobic Moment Analysis and Molecular Dynamics Supplementing Crystallographic Data
Creator: Reinfelds, Pauls Edvins
Date: 2012-07-18, 2012-07
Description: Dystrophin is a rod shaped protein consisting of amino- and carboxy-terminal binding domains linked by a large central rod composed of 24...
Show moreDystrophin is a rod shaped protein consisting of amino- and carboxy-terminal binding domains linked by a large central rod composed of 24 homologous copies of the STR motif and 5 non-homologous regions termed hinges. There are no high-resolution crystallographic structures available for the STR repeats. This work yielded protein crystals and data sets of two STR fragments (d5 & d16-17). Though unable to produce a high resolution structure, this work examines the physical properties of the rod region utilizing hydrophobic moment analysis and molecular dynamics to suggest flexibility among the helices of the STR fragments. Helical shifting appears to possibly occur among the more stable STR tandems to increase the cooperation among certain adjacent fragments. A full understanding of how these properties vary along the length of the rod has implications for the engineering of these rods regions in future dystrophin therapies.
Ph.D. in Biology, July 2012
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Title: REGULATION OF THE CELL DEATH SIGNALING PATHWAY IN ANDROGEN-INDEPENDENT PROSTATE CANCER CELLS
Creator: Lin, Yuting
Date: 2012-04-16, 2012-05
Description: Prostate cancer is the 2nd leading cause of cancer death in American men, mainly due to therapy-resistance in the advanced stage, androgen...
Show moreProstate cancer is the 2nd leading cause of cancer death in American men, mainly due to therapy-resistance in the advanced stage, androgen-independent prostate cancer (AIPCa). One major defect is that the cancer cells are insensitive to apoptosis induced by androgen ablation, chemotherapy or radiation therapy. However, the underline molecular mechanism still remains unclear. In this thesis, we focused on cell death signaling regulation in the development of AIPCa cells. We first show that up-regulation of Bcl-2, an anti-apoptotic oncogene, is required for the transition of prostate cancer cells from an androgen-dependent to an androgen-independent growth stage. Knockdown Bcl-2 impairs the transition process and blocks androgen-independent prostate tumor formation in vivo. Second, we show that Androgen-receptor (AR), which is generally considered as a survival factor in prostate cancer, promotes stress-induced apoptosis in AIPCa cells. AR promotes apoptosis through augmenting the mitochondrial translocation of Bax, a pro-death family member of Bcl-2. Finally, we show that AR can execute both pro-death and pro-survival events in same AIPCa cells. The AR pro-survival role is transcription-dependent, while its pro-death activity is transcription-independent. Interestingly, the AR exerts both functions through regulating p21 and JNK signaling pathways. These findings will help us to understand the dynamic survival signaling process in the development and progression of AIPCa. The key molecules identified here also provides potential therapeutic targets for the treatment of prostate cancer.
Ph.D. in Biology, May 2012
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Title: DEVELOPMENT OF A DIGITAL HUMAN BRAIN ATLAS
Creator: Zhang, Shengwei
Date: 2013, 2013-05
Description: A digital human brain atlas plays a crucial role in brain mapping for the neuroimaging community. Traditionally, a digital brain atlas...
Show moreA digital human brain atlas plays a crucial role in brain mapping for the neuroimaging community. Traditionally, a digital brain atlas contains anatomical information, while structural properties are not presented. Recent development of diffusion tensor imaging (DTI) allows for unique acquisition of information regarding the microstructure of brain tissue. The accuracy of the spatial normalization and subsequent comparisons is contingent upon the use of a DTI template representative of the micro-architecture of the human brain. The previously developed “IIT DTI brain template” was produced in ICBM-152 space. However, low-dimensional registration was used, leading to a mismatch of DTI information across subjects and a mismatch of the anatomy in the IIT and ICBM-152 templates. In this thesis, a significantly improved DTI brain template in ICBM-152 space was developed. The accuracy of spatial normalization in DTI data depends on the quality of data, the effectiveness of the registration technique, and the characteristics of the DTI brain template. Both study-specific and standardized human brain DTI templates exist. The role of both types of templates in spatial normalization warrants further investigation. In this thesis, the effect of standardized and study-specific human brain DTI templates on the accuracy of spatial normalization was investigated. Conventional atlas-based white matter (WM) segmentation is widely used for automated selection of ROI on DTI investigations. However, it suffers from misregistration and inaccurate spatial transformation across subjects. Skeletonized atlasbased segmentation was recently adopted in several DTI studies. However, the use of xiii skeletonized atlas-based segmentation in studies of WM ROIs has not yet been evaluated. In this thesis, the effects of conventional and skeletonized atlas-based segmentation on DTI investigations of WM ROIs were compared. An accurate digital human brain atlas containing different types of high quality MRI data and anatomical labels for both WM and gray matter (GM) in standardized space is desirable for a variety of brain imaging studies. The IIT2 DTI template was developed recently in ICBM-152 space. In this thesis, the quality of the IIT2 template was further enhanced. Furthermore, this publicly available resource was extended into a comprehensive GM atlas of the human brain.
PH.D in Biomedical Engineering, May 2013
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Title: INVESTIGATING THE SIGNIFICANCE OF HALF-SATURATION COEFFICIENTS ON WASTEWATER TREATMENT PROCESSES
Creator: Shaw, Andrew Robert
Date: 2015, 2015-05
Description: This research is focused on the half-saturation coefficient (KS), which is an important, but often overlooked, parameter in the Monod equation...
Show moreThis research is focused on the half-saturation coefficient (KS), which is an important, but often overlooked, parameter in the Monod equation commonly used to describe biological wastewater treatment processes. Following an initial literature review, the research uses data for a denitrifying activated sludge process to show that KS is a function of the maximum rate and, further, that the relationship can be described either using a simple linear regression or by modeling diffusion explicitly. Building on this initial investigation of a particular treatment system, the research introduces and uses a “porter-diffusion” model that approximates diffusion to a linear equation for KS in the Monod equation. This is used to describe the linear relationship between KS and maximum rate for four different biological wastewater treatment systems. Finally, a sensitivity analysis is carried out on the parameters in the porter-diffusion model to show that r0 – a measure of cell size or diffusion distance – is the most sensitive parameter for a simple activated sludge process model based on a modified version of the International Water Association (IWA) activated sludge model #1 (ASM1). Overall this research has shown that in all of the biological wastewater treatment systems investigated in this thesis: (1) KS is not a constant but is a function of the maximum rate; (2) diffusion is a dominant mechanism that influences KS; (3) that a suitable expression for KS can be estimated using the porter-diffusion model, a linear data fit, or by modeling diffusion explicitly; and (4) measurements of KS in the laboratory must be carried out at the same food-to-microorganism (F/M) ratio as the full-scale system under investigation.
Ph.D. in Civil Engineering, May 2015
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Title: ACTIVE LEARNING WITH RICH FEEDBACK
Creator: Sharma, Manali
Date: 2017, 2017-07
Description: One of the goals of artificial intelligence is to build predictive models that can learn from examples and make predictions. Predictive models...
Show moreOne of the goals of artificial intelligence is to build predictive models that can learn from examples and make predictions. Predictive models are useful in many domains and applications such as predicting fraud in credit card transactions, predicting whether a patient has heart-disease, predicting whether an email is a spam, predicting crime, recognizing images, recognizing speech, and many more. Building predictive models often requires supervision from a human expert. Since there is a human in the loop, the supervision needs to be as resource-efficient as possible to save the human’s time, cost, and effort in providing supervision. One solution to make the supervision resource-efficient is active learning, in which the active learner interacts with the human to acquire supervision, usually in the form of labels, for a few selected examples to effectively learn a function that can be used to make predictions. In this thesis, I explore more intuitive and effective use of human supervision through richer interactions between the human expert and the learner, so that the human can understand the learner’s reasoning for querying examples, and provide information beyond just the labels for examples. Traditional active learning approaches select informative examples for labeling, but the human does not get to know why those examples are useful to the learner. While interacting with the learner to annotate examples, humans can provide rich feedback, such as provide their prior knowledge and understanding of the domain, explain certain characteristics of the data, suggest important attributes of the data, give rationales for why an example belongs to a certain category, and provide explanations by pointing out features that are indicative of certain labels. The challenge, however, is that traditional supervised learning algorithms can learn from labeled examples, but they are not equipped to readily absorb the rich feedback. In this thesis, we enable the learner to explain its reasons for selecting instances and devise novel methods to incorporate rich feedback from humans into the training of predictive models. Specifically, I build and evaluate four novel active learning frameworks to enrich the interactions between the human and learner. First, I introduce an active learning framework to reveal the learner’s perception of informative instances. Specifically, we enable the learner to provide its reasons for uncertainty on examples and utilize the learner’s perception of uncertainty to select better examples for training the predictive models. Second, I introduce a framework to enrich the interaction between the human and learner for document classification task. Specifically, we ask the human to annotate documents and provide rationales for their annotation by highlighting phrases that convinced them to choose a particular label for a document. Third, I introduce a framework to enrich the interaction between the human and learner for the aviation domain, where we ask subject matter experts to examine flights and provide rationales for why certain flights have safety concerns. Fourth, I introduce a framework to enrich the interaction between the human and learner for document classification task, where we ask humans to provide explanations for classification by highlighting phrases that reinforce their belief in the document’s label and striking-out phrases that weaken their belief in the document’s label. We show that enabling richer interactions between the human and learner and incorporating rich feedback into learning lead to more effective training of predictive models and better utilization of human supervision.
Ph.D. in Computer Science, July 2017
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Title: HIGH GAIN HIGH EFFICIENCY RESONANT DC-DC CONVERTER
Creator: Shang, Fei
Date: 2016, 2016-12
Description: Low voltage power sources such as batteries, solar panels, and fuel cells have played an important role in applications such as automotive...
Show moreLow voltage power sources such as batteries, solar panels, and fuel cells have played an important role in applications such as automotive system, renewable energy power generation and so on. These applications of the low voltage power sources require a high gain DC-DC step-up converter. Research in this area shows great improvements for the converter topologies. As the power requirements keep increasing, the converter is going to sustain a very high input current. This high current can bring many design challenges in the existing topologies, such as high component current stress and power loss, complex and costly design for magnetic components, high input current ripple, etc. To address these challenges, a new topology of high gain DCDC step-up converter is needed. Evaluation of current high gain DC-DC converter topologies introduces the idea of the new topology which combines the advantages of different topologies and techniques. The new topology of high gain DC-DC converter suitable for low-voltage-high-current application is proposed in this dissertation. It consists of interleaved step-up topology, resonant circuit, and high frequency transformer. The topology has many merits such as high gain capability, high efficiency, low components stress and requirement of the transformer, simple topology with less number of active switching device, and easy to control. The dissertation carries out theoretical analysis of the proposed topology under different operating modes and the voltage gain has been deduced for each mode. The high voltage gain capability comes from 3 parts, which are interleaved step-up function, transformer turns-ratio and output voltage doubler circuit. Some variants of the topology make it more practical in many applications. In order to realize the design of the proposed converter, the design guidelines of major circuit components have been well studied in this dissertation. The switching power devices current stress and power loss are discussed in detailed to show the trend of their variation under different operating modes. The selection of transformer turns-ratio with the consideration of its impact to the component stress and power loss has been fully analyzed. The design method of the resonant tank is also well studied based on the resonant component value selection and its influence to the other components. Input inductor design is related to the current ripple requirement and this relationship is discussed thoroughly. These guidelines can be used to support the practical design of the proposed converter for different specifications. An effective output voltage regulation of the converter is essential for the proposed converter. To design a proper controller of the converter, the system transfer function is needed. The methods of system dynamic modeling have been fully studied in this dissertation. System dynamic state-space models are acquired by using generalized averaging method and the results validate the effectiveness of the method. Small signal model of the converter is achieved by linearization of the dynamic model around the operating points and system transfer functions are available at di↵erent operating points. The stability study indicates that the system is stable at all operating points, though there are several transfer functions at some operating points containing RHP zeros which can cause system unstable if the closed-loop controller is poorly designed. The parameter sensitivity study shows that the system transfer function is not greatly affected by the variation of the leakage inductance and load resistance. A design of PI controller is introduced in the dissertation and closed loop control of the converter is implemented to achieve the output voltage regulation. Simulations in PSIM and MATLAB Simulink have been carried out to validate the circuit operation and support the design analysis. A 2kW prototype has been built for experimental testing. The experimental results are in a good agreement with the theoretical analysis and efficiency of over 95% has been achieved for the nominal operating point.
Ph.D. in Electrical Engineering, December 2016
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Title: SEISMIC STUDY OF DUCTILE AND NON-DUCTILE CONCENTRICALL1 BRACED FRAMES
Creator: Sutchiewcharn, Narathip
Date: 2013, 2013-07
Description: Braced Frames, both ductile and non-ductile systems, are in high demand due to their considerable strength and attractiveness. Therefore, the...
Show moreBraced Frames, both ductile and non-ductile systems, are in high demand due to their considerable strength and attractiveness. Therefore, the better understanding of their behaviors will be beneficial, in which, is the focus in this study. With different failure modes expected based on design methodology, the study of non-ductile system is focused on connections and their contributions toward performance of frame systems, while the ductile system is concentrated on the behavior of braces itself. For non-ductile system with the model-based simulation approach, local brace connection models were developed extending from the validation with the existing specimens. Then, the extensive seismic global performances including local joints, from both local brace and gravity frame connections, are evaluated with the adaptation of collapse methodology outlined in FEMA-P695. For ductile system, with the expectation of hinges formed in braces causing by buckling, the global performances under reversal loadings, e.g. ground motions, are in jeopardy due to the strength degradation. Taking advantage of FEM simulations in addition to testing, the proposed tube-in-tube brace configuration is introduced as buckling-controlled brace (BCB). The effects of parameters are studied using analytical models. The performances observed from proposed tube-in-tube configuration are satisfied under both monotonic and cyclic loadings.
PH.D in Civil Engineering, July 2013
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Title: DRUG UPTAKE AND RELEASE BY STIMULI RESPONSIVE CYLINDRICAL AND SPHERICAL GELS
Creator: Ninawe, Pravin Ramkrishna
Date: 2011-08, 2011-07
Description: ABSTRACT Polymeric gels that undergo deformation upon appropriate changes in pH or temperature have considerable promise as drug delivery...
Show moreABSTRACT Polymeric gels that undergo deformation upon appropriate changes in pH or temperature have considerable promise as drug delivery vehicles. Uptake of drug macromolecules into swelling and non-swelling cylindrical and spherical gels and release of drug macromolecules from deswelling and non-deforming gels into a target fluid are investigated here. A mathematical model for gel-solution composite, a composite of a distributed parameter system (gel spheres or cylinders) and a lumped parameter system (surrounding solution), is developed. The polymer network displacement in swelling/deswelling gels is described by a stress diffusion coupling model. The analytical solution for network displacement is used to predict solvent intake by swelling gels, solvent efflux from deswelling gels, and changes in pressure, porosity and effective drug diffusivity resulting from network displacement. These in turn influence drug uptake during and after gel swelling and drug release from gel during and after gel deswelling. Numerical results illustrate benefits of gel swelling for drug loading and merits of different modes of drug release. Also, the attempt is made to analyze he effect of gel mesh size on the loading and release of large molecular weight drugs. Comparisons are made, as concerns drug uptake and drug release, with gels not subject to deformation. As a special case of application of the above developed model, we tried to simulate drug delivery to the human eye. Since, the therapeutic modalities for posterioreye diseases involve mostly interventions through the anterior eye, which are difficult for physicians and patients alike, sustained drug delivery to the posterior eye is gaining importance. A study for sustained delivery of an anti-VEGF agent (IgG) to the posterior eye from an implant, made of poly(N-isopropylacrylamide) (NIPAM) and placed episclerally, is presented. The model developed in the study is used to simulate the phase transition of the implant made of a thermo-sensitive polymer. The study xvii utilizes compartments for various eye tissues, with individual compartments considered to be completely mixed and drug transport between compartments occurring by one-dimensional diffusion. Further implementation of this model to predict drug concentrations in the eye tissues to arrive at optimum drug loading conditions is also presented here.
Ph.D. in Chemical Engineering, July 2011
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Title: Development of Genetically Engineered Aromatase Overexpressing and Aromatase Inhibitior Resistant Breast Cancer Cell Lines to Study Possible Therapeutic Implications of a Novel Antiprogestin
Creator: Gupta, Akash
Date: 2012-05-07, 2012-05
Description: Aromatase inhibitors (AI) are considered as a first line therapy for ER+PR+ breast cancers. However, many patients acquire resistance to AI....
Show moreAromatase inhibitors (AI) are considered as a first line therapy for ER+PR+ breast cancers. However, many patients acquire resistance to AI. In this study, we determined the antiprogestin CDB-4124 (Proellex) in aromatase overexpressing and Letrozole resistant human breast cancer cell lines. Mechanism of antiproliferative action of Proellex was also explored. For these studies we generated aromatase overexpressing T47D (T47Darom) and respective control (T47Dcon) breast cancer cell lines by stable transfection with plasmid containing CYP19A1 gene, or empty vector respectively. Letrozole resistant cell line (T47DaromLR) was generated by incubating T47Darom cells for 75 weeks in the presence of 10μM Letrozole. Cell proliferation was determined by MTT or Crystal violet assays. Gene expressions were quantified by quantitative RTPCR whereas proteins were identified by western blot analyses, flow cytometry and immunofluorescence staining. Aromatase activity was determined by estradiol ELISA. The effects of Proellex on the anchorage independent growth were measured by soft agar colony formation. Statistical differences between the various groups were determined by Student’s ‘t’ test or ANOVA followed by Bonferroni’s post hoc test. Results showed that T47Darom and T47DaromLR cell lines had significantly higher aromatase expression (mRNA; 80-90 fold and protein) and as a result exhibited increased aromatization of testosterone to estradiol as compared to T47Dcon. Both these cell lines showed enhanced growth in the presence of Testosterone (50%to 60%). In T47DaromLR cells increased PR-B and EGFR expression as compared to T47Dcon cells was observed. Proellex and other known aromatase inhibitors (Letrozole, Anastrozole, and Exemestane) inhibited testosterone induced cell proliferation and anchorage independent growth of T47Darom cells. Cell growth inhibition was significantly greater when cells were treated with Proellex or other AIs. Proellex inhibited mRNA and protein levels of PR-B, reduced PRB/p300 complex formation in the nuclei and significantly reduced EGFR expression in T47Darom cells. Our results in the present study indicate that antiproliferative effect of Proellex is probably due to PRB / EGFR modulation in ER+PR+, aromatase expressing cells. Overall these results suggest that antiprogestin, Proellex can be developed as a possible treatment strategy for aromatase overexpressing ER+/PR+ breast cancer patients as well as for aromatase inhibitor resistant breast cancer patients. Mouse mammary organ culture (MMOC) has been classically employed for evaluating the efficacy of chemopreventive agents against development of carcinogeninduced preneoplastic lesions. Efficacy of chemopreventive agents observed in MMOC correlates well with that observed in in-vivo carcinogenesis models. In the present study, we developed a new ex-vivo Human in Mouse organ culture model which mimics in-vivo orthotopic breast cancer model. Since we introduced human breast cancer cells in mouse mammary gland and cultured in vitro, this model is termed as human Breast cancer (BCA) in Mouse Mammary Organ Culture (BCa-in-MMOC). Three to four week old female Balb/c mice were sensitized with estradiol (1mg) + progesterone (1mg) for 9 days. On the 10 th day animals were sacrificed and 2.5x10 4 T47D parental or T47D aromatase overexpressing cells were injected into the fourth pair of mammary glands. The glands were excised then cultured at 37C under 95% O2 / 5% CO2 in hMEM medium containing 10% charcoal stripped FBS supplemented with Testosterone (1nM) and progesterone (1mM) and growth promoting hormones (5 μg insulin, 5 μg prolactin per ml medium). At the end of the experiment, the glands were fixed in formalin. The paraffin embedded sections (longitudinal) of entire glands were processed for histopathological examination (H and E stain) and immnohistochemical staining of various proteins. Mammary glands were evaluated for the presence of T47D cells, their growth pattern and their molecular responsiveness to estradiol. T47D cells (both types) injected into mammary glands were easily identified against mouse cells by intense human specific CK18 immunofluorescence staining. Histopathological observation of mammary gland sections showed that growth pattern of injected cancer cells was identical to that observed of breast cancer cells injected in vivo in athymic mice. Interestingly, clusters of cancer cells in the mammary gland stroma appear similar to those observed in breast tumors in women. Cancer cells injected into glands survived and continued to grow (as evident from Ki-67 immunostaining) after 15 days in culture. Cancer cells maintained their original characteristics (ER+, PR+, EGFR+, and aromatase). T47D cells with enhanced aromatase expression growing in the MMOC could metabolize testosterone to estrogen, which resulted in enhanced cell proliferation and induction of estrogen target genes such as ER and PR-B. Mouse mammary glands with T47D aromatase overexpressing cells also showed changes typical to estrogenic milieu. In summary this model provides a novel, inexpensive ex vivo model, which could be used to study effects of therapeutic agents on the cancer cells growing in orthotopic micromilieu.
Ph.D. in Biology, May 2012
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Title: OPTIMIZING THE PERFORMANCE OF BUILDING ENVELOPE FOR ENERGY EFFICIENCY CONSIDERING ADAPTIVE THERMAL COMFORT: A CASE OF TROPICAL CLIMATE IN DHAKA
Creator: Rahman, Anisur
Date: 2014, 2014-05
Description: As demand for fossil fuel increases and availability decreases, energy consumption reduction in building becomes critical component of a city...
Show moreAs demand for fossil fuel increases and availability decreases, energy consumption reduction in building becomes critical component of a city’s comprehensive energy strategy. The performance of a building’s envelope is pivotal to the energy consumption of office buildings and it must mediate between external climate conditions and people’s comfort. By optimizing a buildings envelope, the heat gain or loss of a building can be manipulated and it can reduce energy consumption. In Dhaka, a widespread desire for office building with glazing areas far greater than the percentage required achieving comfortable thermal and light levels, with high solar transmittance, is directly at odds with the need to curb cooling-related energy use. When addressing energy efficiency in a building, it is necessary to account for local climate first and foremost to define the thermal comfort condition. This determines the energy demand and consumption. Passive cooling and natural ventilation, when combined with appropriate window ratios and sun shading strategies, can reduce mechanical system energy demands significantly. This research presents a workflow that integrates adaptive thermal comfort, natural ventilation and envelope optimization to develop a pre-policy statement as a guideline for energy efficient office buildings in Dhaka, Bangladesh. First, a common practice baseline model was developed from data collected from energy audits to gain a clear understanding of the energy consumption in typical existing office buildings in Dhaka. Adaptive Comfort Algorithms from EN15251 and ASHRAE 55 were used to calculate variable set-points related to running mean and monthly mean xv of the outdoor temperature respectively. Variable set-points have been used in EnergyPlus AirflowNetwork to determine the potential energy saving of adaptive comfort control strategy of HVAC equipment and for encouraging natural ventilation envelope strategies to create comfortable indoor environment in the local climatic context of Dhaka. A method of envelope optimization was developed by combining an optimization tool with a building energy simulation tool to determine the optimum solution for improving building envelope performance. GenOpt, a generic optimization program, has been coupled with EnergyPlus for this optimization. Then, the values of envelope and glazing parameters for optimum energy performance were determined using this automatic optimization method. The reduction of a building’s energy consumption was also addressed with regards to capital and operational costs. An economic analysis was performed to establish a correlation between energy saving and capital cost increase associated with the energy-efficient envelope measures. This research shows that significant reductions in energy consumption are possible with the application of fundamental, but not complicated, changes to local building codes and establishment of a comprehensive energy conservation code. This reduction could be even greater if inhabitant behavior can be changed, if users start to take more responsibility for their interaction directly with a building’s envelope and systems to have some degree of control over daily comfort. Technology and design innovations should be utilized for adaptive threshold of appropriate, responsive architecture.
PH.D in Architecture, May 2014
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Title: MARKET DOMINANT PLUG-IN HYBRID ELECTRIC VEHICLES OPTIMAL CONTROL FOR MINIMUM CHARGING COST AND V2G REGULATION SERVICE
Creator: Li, Zhihao
Date: 2012-07-23, 2012-07
Description: Plug-in hybrid electric vehicles (PHEVs) share the characteristics of hybrid electric vehicles (HEVs) and electric vehicles (EVs), employing...
Show morePlug-in hybrid electric vehicles (PHEVs) share the characteristics of hybrid electric vehicles (HEVs) and electric vehicles (EVs), employing electric motors and internal combustion engines (ICEs) for propulsion as well as large capacity batteries for energy storage. With ICEs and fuel tank on board, PHEVs do not have the range limitations posed by EVs; large capacity battery promises long distance all-electric range (AER) and fuel efficiency improvement. PHEVs will play a vital role in future as a sustainable transportation system, promising for environment, energy solution, and economy. It is estimated that by 2015, the total number of PHEVs in the world will be approximately 1.7 million with the U.S. marking leading the industry with about one million PHEVs. Growing penetration of PHEVs will place significant impacts on the grid, either as additional electric loads or potential assets which could provide various vehicleto- grid (V2G) services. There are four potential grid services that PHEVs can provide: base load generation, peak load shaving, spinning reserve, and regulation. PHEVs are not competitive in base load or peak load markets due to limited battery capacities. In addition, PHEVs are not real generating units and the energy stored in batteries is absorbed from grid. V2G support is taken into account as frequency regulation by participating in ancillary service markets. However, if implemented without proper control, large scale PHEVs will cause increases of peak load and destabilize the grid. This paper proposes an optimization strategy to maximize V2G profits as well as to minimize charging costs. The optimization strategy is based on a forecast of future electricity price for both residential electricity and regulation market. Due to the stochastic nature of electricity price, final prices cannot be deterministically calculated. Therefore, the addressed problem is solved by stochastic dynamic programming to find the economically optimal solution with price uncertainties. Constraints caused by vehicle utilization as well as technical limitations are taken into account. Additional costs arising from discharging batteries for ancillary service can be partially or completely compensated by V2G profits. In this Ph.D. research work, economical impacts of PHEV fleet are examined in Pennsylvania Jersey Maryland (PJM) regulation market. The major contributions of this paper are: Mathematically model the optimal control of PHEV with comprehensive transition function and cost function; A full study of battery life and cost that considers different ageing factors; A stochastic study of uncertainty and volatility in electricity price; Include battery degradation and price uncertainty in the comprehensive function for optimal control.
Ph.D. in Electrical Engineering, July 2012
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Title: NOVEL ELECTROLYTES FOR LITHIUM-ION BATTERIES
Creator: Ma, Qiang
Date: 2014, 2014-12
Description: With the increasing needs for creating new clean and sustainable energy sources to substitute traditional fossil fuel at present, lithium-ion...
Show moreWith the increasing needs for creating new clean and sustainable energy sources to substitute traditional fossil fuel at present, lithium-ion batteries as one of the most promising energy storage devices have been shown much attention. As a necessary and important component in a battery system, electrolytes need to be expanded according to the cell's requirements for varied applications. Especially nowadays, researches for safe, environmentally friendly and cost effective battery electrolyte systems are very challenging and active all around the world. This dissertation describes three different approaches to achieve an improved electrolyte system for lithium-ion batteries. For solid polymer electrolytes (SPEs), three different plasticizers have been synthesized and incorporated into a conventional poly(ethylene oxide) (PEO)-based SPEs. The room temperature ionic conductivity was significantly improved by decreasing the glass transition temperature of the polymer matrix. One new poly(ethylene glycol)-grafted-polybutadiene was designed and synthesized. Different weight ratios of new co-polymer and PEO mixtures were studied for using as polymer host for SPEs. For liquid electrolytes, two different strategies have been investigated. One is that series of small molecular weight molecular liquids were designed and synthesized to improve the low temperature performance and safety of commonly used organic carbonates systems. Different concentrations of lithium bis-trifluoromethanesulfonimide (LiTFSI) solutions were studied to find the optimized combinations. A series of new zwitterionic liquids (ZILs) were also designed and synthesized as ionic liquid electrolytes. However, this type of electrolytes is too viscous to provide a satisfied ionic conductivity, thus 2-nitropropane as a co-solvent was used here to reduce the viscosity. Last, a series of novel diphosphate-based tetra lithium salts was synthesized and studied. Solartron electrochemical analyzer was used to test ionic conductivity, electrochemical window and lithium cation transference number. The technologies of thermal gravimetric analysis and differential scanning calorimetry were used to study thermal properties of electrolytes. Furthermore, some future plans of studies in lithium-ion battery electrolyte field were also discussed.
Ph.D. in Chemistry, December 2014
Ph.D. in Chemistry, December 2014
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Title: EVALUATION OF TALL OFFICE BUILDING FORM TO ENHANCE WIND ENERGY PRODUCTION IN BUILDING INTEGRATED WIND TURBINE, A PERFORMANCE BASED APPROACH FOR EARLY DESIGN STAGE
Creator: Abdolhossein Pour, Farid
Date: 2014, 2014-12
Description: A newly emerging way to promote sustainability in the built environment is through the incorporation of wind power within buildings, resulting...
Show moreA newly emerging way to promote sustainability in the built environment is through the incorporation of wind power within buildings, resulting in minimum transmission losses (distributed generation). However, the effectiveness of the proposed solutions are seriously dependent on early integration with the architectural design process. Wind power is considered a potential renewable energy source in tall buildings due to the possibility of accessing greater wind velocities at higher altitudes. In addition, airflow patterns around buildings are considerably influenced by a buildings’ geometric characteristics. Hypothetically, proper modification of building form can turn this unstructured phenomenon in to a massive concentrator effect, capable of boosting power production in tall buildings with an integrated wind turbine (BIWT). These aerodynamic modifications are typically evaluated via CFD simulation or wind tunnel testing. However, these methods are too expensive and time-consuming to analyze all annual fluctuations of local wind regimes (velocity, direction, and density) and is therefore inappropriate for use in early design stages when architectural concepts quickly evolve. As a result, existing wind analysis techniques are often used under simplified conditions (steady state analysis, single velocity, and angle). This approach simply disregards the wide variety of other criteria influencing “BIWT annual energy output” including fluctuations of local wind regimes, and surrounding urban terrain roughness. This research seeks to address the issues indicated above, and proposes a performance based parametric design tool, primarily for the early design stages when architectural concepts evolve rapidly. The automated output delivers real time assessment of BIWT potential energy enhancement for each alternation of the concept, as well as analysis of multiple BIWT typologies simultaneously. The parametric tool employs hourly weather data, different terrain condition mathematical models, and two databases of CFD measurements to approximate annual energy enhancement as result of BIWT geometrical transformations. The tool develops a decision mechanism to find the best BIWT typology and optimum angle, based on the long-term local climatic trends and adjacent terrain context. The outcome of this dissertation is an automated parametric tool which addresses all above indicated difficulties associated with incorporation of current wind analysis method and the architectural design process of BIWT.
Ph.D. in Architecture, December 2014
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Title: INVESTIGATION OF OXIDATIVE DEGRADATION AND DEGRADATION MITIGATION IN POLYMER ELECTROLYTE FUEL CELLS USING IN-SITU FLUORESCENCE SPECTROSCOPY
Creator: Prabhakaran, Venkateshkumar
Date: 2014, 2014-05
Description: Hydrogen/air polymer electrolyte fuel cells (PEFCs) possess high efficiency and modularity. However, significant technical advances are...
Show moreHydrogen/air polymer electrolyte fuel cells (PEFCs) possess high efficiency and modularity. However, significant technical advances are required to facilitate their commercialization in targeted applications. A key issue is component durability under an array of adverse operating conditions. The polymer electrolyte membrane (PEM) in a PEFC is one of the components whose long-term durability is of concern since it undergoes mechanical, thermal, and chemical degradation during fuel cell operation. The chemical (oxidative) degradation processes that take place in a PEM are attributed to reactive oxygen species (ROS) that are generated in-situ during PEFC operation. It is essential to quantify the rate of ROS generation within the PEM during PEFC operation prior to proposing an effective degradation mitigation strategy. This is a daunting challenge, given the high reactivity and very short lifetime of these species. The rate of generation of ROS within the PEM of an operating PEFC was accurately measured, for the very first time, using in-situ fluorescence spectroscopy. The influence of fuel cell operating parameters (temperature, relative humidity, and electrode potential/current density) on the rate of ROS generation was studied. The ROS generation reaction rate constant (estimated from the in-situ fluorescence experiments) correlated perfectly with the macroscopic rate of PEM degradation (estimated from the ex-situ fluoride emission rate) across all conditions, demonstrating unequivocally for the first time that a direct correlation existed between in-situ ROS generation and PEM macroscopic degradation. The utility of using regenerative free radical scavengers (FRS) such as CeO2 nanoparticles to mitigate ROS induced PEM degradation was also demonstrated using xxii xxii in-situ fluorescence spectroscopy. Though CeO2 was shown to scavenge the generated ROS, its scavenging efficacy declined with time and hence it was not truly a regenerative scavenger. The FRS efficacy was found to scale with the number of surface oxygen vacancies in its non-stoichiometric lattice. The regenerative FRS activity of CeO2 nanoparticles was improved by tuning its lattice via nitrogen doping (N-doping). It was demonstrated that N-doping increased both the number of Ce3+ active clusters in the lattice and the Ce-O bond distance; these structural attributes enhanced the regenerative ROS scavenging activity of CeO2. In addition, the influence of catalyst support on PEM degradation during PEFC operation was studied. A novel and highly corrosion-resistant non-carbon catalyst support (RuO2-SiO2; RSO) developed by our group was compared against a benchmark carbonbased catalyst support (Vulcan XC 72; C). It was found that the ROS generation rate, and hence the macroscopic PEM degradation rate, was lower when RSO was used as the electrocatalyst support in place of C. In conjunction with its remarkable corrosionresistance, this finding further illustrated the viability of RSO as an outstanding PEFC electrocatalyst support. Apart from PEM degradation, the applications of fluorescence spectroscopy in the context of other electrochemical devices was also discussed. Proofof- concept studies to study the Pt dissolution rate (in PEFC electrodes) and vanadium crossover rate (in vanadium redox flow batteries) were successfully undertaken; these areas, along with probing degradation processes secondary batteries, would be rich grounds for future study.
PH.D in Chemical Engineering, May 2014
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Title: INVESTIGATION OF ANISOTROPIC THERMAL TRANSPORT IN CROSS-LINKED POLYMERS
Creator: Simavilla, David Nieto
Date: 2014, 2014-07
Description: Thermal transport in lightly cross-linked polyisoprene and polybutadine subjected to uniaxial elongation is investigated experimentally. We...
Show moreThermal transport in lightly cross-linked polyisoprene and polybutadine subjected to uniaxial elongation is investigated experimentally. We employ two experimental techniques to assess the e↵ect that deformation has on this class of materials. The first technique, which is based on Forced Rayleigh Scattering (FRS), allows us to measure the two independent components of the thermal di↵usivity tensor as a function of deformation. These measurements along with independent measurements of the tensile stress and birefringence are used to evaluate the stress-thermal and stress-optic rules. The stress-thermal rule is found to be valid for the entire range of elongations applied. In contrast, the stress-optic rule fails for moderate to large stretch ratios. This suggests that the degree of anisotropy in thermal conductivity depends on both orientation and tension in polymer chain segments. The second technique, which is based on infrared thermography (IRT), allows us to measure anisotropy in thermal conductivity and strain induced changes in heat capacity. We validate this method measurements of anisotropic thermal conductivity by comparing them with those obtained using FRS. We find excellent agreement between the two techniques. Uncertainty in the infrared thermography method measurements is estimated to be about 2-5 %. The accuracy of the method and its potential application to non-transparent materials makes it a good alternative to extend current research on anisotropic thermal transport in polymeric materials. A second IRT application allows us to investigate the dependence of heat capacity on deformation. We find that heat capacity increases with stretch ratio in polyisoprene specimens under uniaxial extension. The deviation from the equilibrium value of heat capacity is consistent with an independent set of experiments comparing anisotropy in thermal di↵usivity and conductivity employing FRS and IRT techniques. We identify finite extensibility and strain-induced crystallization as the possible causes explaining our observations and evaluate their contribution making use of classical rubber elasticity results. Finally, we study of the role of evaporation-induced thermal e↵ects in the wellknow phenomena of the tears of wine. We develop a transport model and support its predictions by experimentally measuring the temperature gradient present in wine and cognac films using IRT. Our results demonstrate that the Marangoni flow responsible for wine tears results from both composition and temperature gradients, whose relative contribution strongly depends on the thermodynamic properties of ethanol-water mixtures. The methods developed here can be used to obtain a deeper understanding of Marangoni flows, which are ubiquitous in nature and modern technology.
Ph.D. in Chemical Engineering, July 2014
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Title: BANDWIDTH ENHANCEMENT OF A COMPACT ANTENNA BY PARASITIC ELEMENTS
Creator: Celebi, Adem
Date: 2015, 2015-05
Description: Antenna structures are playing a major role in wireless systems, including communication systems, radars, satellite systems, information...
Show moreAntenna structures are playing a major role in wireless systems, including communication systems, radars, satellite systems, information networks and medical diagnostic systems. In these systems, external antennas are widely used, especially for devices with metallic enclosures. One of the common requirements for the ex- ternal antennas is the need for achieving small dimension while keeping the antenna performance optimized. In this respect, electrically small antennas (ESAs) are em- ployed. Realizing the design requirements of an ESA has been a challenge for antenna designers because some of the parameters such as large bandwidth and reasonably high input impedance are in conflict with the small antenna dimensions. A compact antenna with parasitic elements for bandwidth enhancement is proposed to address these issues for use with mobile devices. Loading the known antenna topologies with other structures could improve the design parameters such as gain, bandwidth, impedance, and beamwidth for antenna topologies which are impossible to achieve with the conventional antennas. In this respect, a parasitic element with a smaller scale is placed within the structure to obtain a second resonance close to the main antennas resonance for an increased bandwidth without increasing the overall dimen- sions of the antenna. This composite antenna is expected to have relatively high input impedances for each of the resonances, thus minimizing the need for an input matching network. A review of related prior work of antenna structures is presented to gain insight into the recent developments and methods in the field. The mini- mum quality factor (Q) and maximum gain of the ESA designs and their theoretical Antenna structures are playing a major role in wireless systems, including communication systems, radars, satellite systems, information networks and medical diagnostic systems. In these systems, external antennas are widely used, especially for devices with metallic enclosures. One of the common requirements for the ex- ternal antennas is the need for achieving small dimension while keeping the antenna performance optimized. In this respect, electrically small antennas (ESAs) are em- ployed. Realizing the design requirements of an ESA has been a challenge for antenna designers because some of the parameters such as large bandwidth and reasonably high input impedance are in conflict with the small antenna dimensions. A compact antenna with parasitic elements for bandwidth enhancement is proposed to address these issues for use with mobile devices. Loading the known antenna topologies with other structures could improve the design parameters such as gain, bandwidth, impedance, and beamwidth for antenna topologies which are impossible to achieve with the conventional antennas. In this respect, a parasitic element with a smaller scale is placed within the structure to obtain a second resonance close to the main antennas resonance for an increased bandwidth without increasing the overall dimen- sions of the antenna. This composite antenna is expected to have relatively high input impedances for each of the resonances, thus minimizing the need for an input matching network. A review of related prior work of antenna structures is presented to gain insight into the recent developments and methods in the field. The mini- mum quality factor (Q) and maximum gain of the ESA designs and their theoretical limitations are then discussed. The features of the antenna designs discussed in the review are used as foundation of the developed antenna structures. The properties and a fabrication method of the proposed antenna are then discussed. A commer- cially available software package based on finite element method is employed to aid in the antenna design. Several antenna prototypes are constructed to verify the design and the accuracy of the simulations. The prototypes are then tested using network analyzers and an RF anechoic chamber with the aim of characterizing the antenna performance in terms of antenna bandwidth and input impedance.
Ph.D. in Electrical and Computer Engineering, May 2015
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Title: DEVELOPMENT OF A MODIFIED LUBRICATED SQUEEZING FLOW TECHNIQUE FOR GENERATING EQUIBIAXIAL ELONGATIONAL FLOWS IN POLYMER MELTS
Creator: Kashyap, Teresita
Date: 2011-04-19, 2011-05
Description: Techniques for measuring the equibiaxial extensional properties of materials are rather scarce, in part due to the difficulty to generate...
Show moreTechniques for measuring the equibiaxial extensional properties of materials are rather scarce, in part due to the difficulty to generate homogeneous flow. The two more acknowledged techniques are rotating clamps and lubricated squeezing flow (LSF). The rotating clamps technique employs the MultiAxiale Dehnung (MAD) rheometer, and data from this method are considered to be the most reliable for equibiaxial extensional flow. Unfortunately, the MAD device does not further exist. The LSF technique, where a sample is deformed by compression between parallel lubricated plates, fails at small deformations due to loss of lubrication. The objectives of this study were to develop a novel experimental technique called continuous lubricated squeezing flow (CLSF), and to study the rheological behavior of polymer melts and other viscous fluids in equibiaxial elongational deformations. The parameters that may affect results from the LSF technique were examined for constant strain rate and step-strain flows. The performance of the LSF method was evaluated in constant strain-rate deformations by direct comparisons of viscosity data from the MAD device. The CLSF technique was developed and validated, also in constant strain-rate deformations, by direct comparison of rheological data from the MAD rheometer. The CLSF technique was used to investigate the equibiaxial extensional flow behavior of monodisperse polystyrene melts. The relaxation modulus for a linear and a branched polymer melt was measured by LSF technique, and time-strain factorability was analyzed. Damping functions were calculated and compared with the tube, slip-link and pom-pom models. The results from this study showed that transient viscosity data from LSF technique are higher than those from the MAD device, and are independent of the polymer and experimental conditions. The behavior exhibited by the LSF data could easily be mistaken for the phenomenon of strain hardening. The new CLSF technique resolved the lubricant thinning problem in LSF. The measured viscosity from CLSF was in excellent agreement with the MAD data, thus, meaningful equibiaxial elongational flow information could be obtained by CLSF technique. The equibiaxial behavior of monodisperse polystyrene melts was linear. The LSF method could successfully be used for step-strain deformations. Time-strain factorability of the relaxation modulus was observed for a linear and a branched melt. Damping function data for the linear polymer showed good agreement with the tube and slip-link models. The relaxation modulus and the damping function of the branched polymer showed significant differences from the pom-pom model predictions.
Ph.D. in Chemical Engineering, May 2011
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Title: SURVIVABLE OPERATION OF THREE PHASE AC DRIVES IN WIND GENERATOR SYSTEMS
Creator: Shi, Xiaodong
Date: 2012-04-06, 2012-05
Description: Recent years have seen significant popularity in the use of wind generators owing to the depletion of natural resources and growing concerns...
Show moreRecent years have seen significant popularity in the use of wind generators owing to the depletion of natural resources and growing concerns about our environment. However, this development has raised issues concerning reliability of the wind turbine components. Among these faults, failure of current sensors is one of most common faults that can bring the wind generator to a standstill and lead to reduction in power yield. In addition, unscheduled maintenance often results in longer downtime and causes reduction of wind plant availability especially for those wind turbines located offshore or in remote areas. This dissertation proposes a survivable drive method to continue to operate the wind turbine in spite of current sensor failure. One of the common control strategies for the optimal of three-phase AC generators is vector control. Therefore, vector control method is implemented in this dissertation for both induction machine and Brushless PMSM. In order to achieve survivability when current sensor fault happens, a simple and effective method which doesn’t rely on current feedbacks is required as a backup control strategy. For this purpose, a digital control strategy is proposed for an induction machine and a Brushless PMSM. In addition, a current sensor failure detection method is designed to trigger the transition and a smooth transition method (only for induction machine) is implemented to ensure the smoothness of the control transition without stopping the system. Simulation and experimental results have been presented to prove feasibility and demonstrate the effectiveness of the proposed strategy.
Ph.D. in Electrical Engineering, May 2012
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