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Title: SECURITY AND PERFORMANCE OPTIMIZATION FOR WIRELESS COMMUNICATIONS
Creator: Wang, Qian
Date: 2012-04-13, 2012-05
Description: Today’s communication systems rely heavily on wireless technologies. The large scale proliferation of wireless technology brings with it a...
Show moreToday’s communication systems rely heavily on wireless technologies. The large scale proliferation of wireless technology brings with it a more serious concern for security since wireless communications introduce multiple avenues for attack and penetration into a network. This dissertation studies two important and fundamental problems in wireless communication security: secure secret key establishment and anti-jamming communication. This dissertation extends the current body of knowledge by proposing a suite of new and novel solutions to enhance and optimize the system performance. A comprehensive study including theoretical analysis and simulative evaluation shows that the proposed solutions can be applied in highly dynamic networking scenarios where traditional security mechanisms may not be sufficient by themselves. The first part of this dissertation develops a novel cooperative key generation protocol to facilitate high-rate key generation in narrowband fading channels, where two keying nodes extract the phase randomness of the fading channel with the aid of relay node(s). In particular, a theoretical upper bound and a more practical upper bound on the maximum secret key rate are successfully established. Numerical examples and simulation studies are also presented to demonstrate that the key rate can be improved by a couple of orders of magnitude compared to the existing physical layer based key generation approaches. The second part of this dissertation develops an adaptive uncoordinated frequency hopping (UFH) protocol for anti-jamming wireless communications. This section of the dissertation introduces the online optimization theory into the solution space and makes the thorough quantitative performance characterization possible for UFH-based anti-jamming communications. The optimality of the proposed algorithms is analytically proved under various message coding scenarios. Simulation results are presented demonstrating the jamming resilience of the learning-based UFH algorithm. The final part of this dissertation presents a jamming-resistant multi-radio multi-channel opportunistic spectrum access protocol for cognitive radio networks (CRNs), where the secondary sender and receiver adaptively choose their channels to operate to maximize the throughput. The convergence of the learning algorithm is investigated and an upper bound on the performance difference between the secondary sender and receiver’s optimal strategies is obtained. The simulation results in this section validate the theoretical analysis and show that even if facing a powerful jammer using myopic policy, the proposed design is still very effective and has strong resilience against jamming.
Ph.D. in Electrical Engineering, May 2012
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Title: SCALABLE RESOURCE MANAGEMENT IN CLOUD COMPUTING
Creator: Sadooghi, Iman
Date: 2017, 2017-05
Description: The exponential growth of data and application complexity has brought new challenges in the distributed computing field. Scientific...
Show moreThe exponential growth of data and application complexity has brought new challenges in the distributed computing field. Scientific applications are growing more diverse with various workloads, including traditional MPI high performance computing (HPC) to fine-grained loosely coupled many-task computing (MTC). Traditionally, these workloads have been shown to run well on supercomputers and highly-tuned HPC Clusters. The advent of Cloud computing has brought the attention of scientists to exploit these resources for scientific applications at a potentially lower cost. We investigate the nature of the cloud and its ability to run scientific applications efficiently. Delivering high throughput and low latency for the various types of workloads at large scales has driven us to design and implement new job scheduling and execution systems that are fully distributed and have the ability to run in public clouds. We discuss the design and implementation of a job scheduling and execution system (CloudKon). CloudKon is optimized to exploit the cloud resources efficiently through a variety of cloud services (Amazon SQS and DynamoDB) in order to get the best performance and utilization. It also supports various workloads including MTC and HPC applications concurrently. To further improve the performance and the flexibility of CloudKon, we designed and implemented a fully distributed message queue (Fabriq) that delivers an order of magnitude better performance than the Amazon Simple Queuing System (SQS). Designing Fabriq helped us expand our scheduling system to many other distributed system including non-Amazon clouds. Having Fabriq as a building block, we were able to design and implement a multipurpose task scheduling and execution framework (Albatross) that is able to efficiently run various types workloads at larger scales. Albatross provides data locality and task execution dependency. Those features enable Albatross to natively run MapReduce workloads. We evaluated CloudKon with synthetic MTC workloads, synthetic HPC workloads, and synthetic MapReduce applications on the Amazon AWS cloud with up to 1K instances. Fabriq was also evaluated with synthetic workloads on Amazon AWS cloud with up to 128 instances. Performance evaluations of Albatross show its ability to outperform Spark and Hadoop on different scenarios.
Ph.D. in Computer Science
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Title: IMPROVING DECISION-MAKING FOR ENERGY PERFORMANCE OF BUILDINGS WITH COMPUTATIONAL TOOLS IN EARLY DESIGN STAGES
Creator: Claussnitzer, Sebastian
Date: 2013, 2013-12
Description: In the early design stages of architectural practice, a relative absence of advanced decision-making processes limits the number of building...
Show moreIn the early design stages of architectural practice, a relative absence of advanced decision-making processes limits the number of building-design options that can be exam- ined for energy e ciency. This paper proposes to improve the design process by enhancing decision-making with computational tools: speci cally, tools that autonomously generate and evaluate thousands of design options. Two di erent tools were prototyped, each utiliz- ing contrasting algorithmic approaches. The rst prototype uses numerical optimization to autonomously explore the design space of a parametric building model, and simulates the annual energy consumption through energy modeling. The second prototype, in contrast, utilizes an exhaustive search to explore the design space of a simpli ed building model. Tens of thousands of simulation results are stored in a database, which users access through web-interfaces in near-realtime. The proposed tools for advanced decision-making enable architects to examine many more building design alternatives than are manually feasible, thus increasing the likelihood of identifying better design options.
M.S. in Architecture, December 2013
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Title: PURIFICATION AND CRYSTAL GROWTH OF INI AND ALLOYS IN1-xTLxI AND IN1-xGAxI FOR APPLICATION IN X-RAY AND GAMMA-RAY DETECTORS
Creator: Riabov, Volodymyr
Date: 2016, 2016-07
Description: The present work is focused on developing new semiconductor materials based on Indium Monoiodide (InI) for application in room temperature X...
Show moreThe present work is focused on developing new semiconductor materials based on Indium Monoiodide (InI) for application in room temperature X-ray and gamma-ray detectors. During past two decades InI was studied as room a temperature detector material due to suitable value of the energy gap and high atomic number of its constituents. The most recent studies include investigations at laboratories of Prof. A. Ostrogorsky at Rensselaer Polytechnic Institute (RPI) and Illinois Institute of Technology (IIT) during period 2009-2013. The present work was focused on (i) purification of starting InI material and (ii) crystal growth of InI and InI based alloys with objective to investigate effects of purification and alloying on crystal structure, electrical and mechanical properties. Purification was performed at Radiation Monitoring Devices (RMD) Inc. by innovative techniques combined with well established methods, such as Zone Refining Under Reactive Atmosphere. At RMD, purification was followed by crystal growth of InI by the travelling molten zone method. Crystal growth of InI and alloys In0.99Ga0.01I, In0.99Tl0.01I, In0.95Tl0.05I was performed by Vertical Gradient Freeze (VGF) Method at IIT. The microstructure of produced crystals was analyzed, and their Knoop micro-hardness was measured. The concentration of the dopants as a function of position along the crystals was analyzed by Glow Discharge Mass Spectrometry (GDMS) technique. Band gap of produced materials was estimated as a function of composition by Near-UV-Visible range spectroscopy. Radiation detectors were manufactured from produced crystals. Their electrical properties, such as resistivity, photosensitivity and charge carrier mobility, were measured and, finally, detection performance was estimated.
M.S. in Mechanical and Aerospace Engineering, July 2016
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Title: PROCESSING OF IRON BASED OXIDE DISPERSION STRENGTHENED ALLOYS
Creator: Siddhanthi, Rohan Ashok
Date: 2011-12-19, 2011-12
Description: In this research the Oxide Dispersion Strengthened (ODS) Steel alloy 14 YWT with composition Fe- 14 Cr – 3 W – 0.4 Ti – 0.25 Y2O3 was...
Show moreIn this research the Oxide Dispersion Strengthened (ODS) Steel alloy 14 YWT with composition Fe- 14 Cr – 3 W – 0.4 Ti – 0.25 Y2O3 was consolidated using liquid phase sintering method and it’s mechanical properties were tested and compared with standard materials. Initially the standard composition was prepared by mechanical alloying and cold compacted in to compression samples and then sintered. The consolidated sample density was determined and their compression tests were performed at various temperatures. To improve the strength aluminum powder was added into the mechanically alloyed samples via milling for 15 minutes with the aim to enhance diffusion by liquefying at higher temperatures. Initially specimens with different weight percentage of aluminum were prepared and it was discovered that 2.5% aluminum addition gave the best results; further testing was carried out at this alloy composition. The tests were carried out for 2 different post sintering processes. Tests were also carried out with copper as the sintering agent. A significant increase in yield strength with the addition of 2.5% Al and 10% cold working was observed.
M.S. in Material Science, December 2011
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Title: ANAEROBIC TREATMENT OF PETROCHEMICAL WASTE FOR DETOXIFICATION AND SOLIDS REDUCTION
Creator: Roy, Ratul
Date: 2015, 2015-07
Description: Lab scale studies were conducted to test the anaerobic digestibility of two waste streams acquired from a petrochemical refinery. The waste...
Show moreLab scale studies were conducted to test the anaerobic digestibility of two waste streams acquired from a petrochemical refinery. The waste streams comprised of a float from the dissolved air flotation (DAF) unit and a waste activated sludge (WAS) from the biological treatment unit. Three semi continuous anaerobic digesters (AD) were fed with DAF, WAS and a combination of the two as substrates. Batch bioassays were used as a preliminary tool to determine the toxicity profiles and the biodegradability of the feeds. Out of the three combinations in AD, mono digestion of WAS yielded the highest gas production whereas feeds with portions of DAF showed inhibition in the overall process. Pretreatment of the feeds through ozonation was utilized in the latter phase of the study that exhibited a marked improvement in the mono digestion of DAF when the hydraulic retention time (HRT) was doubled. Both the solids destruction and the biogas recovery increased to 49% and 106 Lbiogas/kgVS respectively. Ozonized WAS saw solids destruction increase by 20% and the biogas recovery was more than double. Whereas ozonized co-digestion led to formation of an emulsified layer which further affected the overall performance and yielded lower biogas. However, pretreatment of influents containing portions of DAF saw substantial removal of volatile organic compounds (VOC) and semi volatile organics (SVOC) going into the lab scale digesters.
M.S. in Environmental Engineering, July 2015
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Title: THE CITY AS A DIGITAL PUBLIC SPACE: DATA-DRIVEN DESIGN AS A SOCIAL LINK
Creator: Shabehpour Setork, Pegah
Date: 2016, 2016-12
Description: We live in an age of instant communication, rapid transportation, and smartphones; an age where the answer to a question can be prompted...
Show moreWe live in an age of instant communication, rapid transportation, and smartphones; an age where the answer to a question can be prompted through voice command. With today’s unparalleled increase in digital information, big data is continuously adapting and developing our society with the support of emerging technologies. This has led to the rise and growth of our virtual communities as communication is primarily done through social media networks. The demise of our physical communities has reduced social interaction within the built environment. Despite this forward thinking and the ability to translate big data into architectural solutions, our urban environments have yet to reflect this. Patterns of human interaction within our cities can be transformed by incorporating and visualizing big data within public infrastructure. As a result, the architectural design process is due for an update. This research project explores the use of a high-speed rail station as a hybrid space for virtual and physical communities by providing an interface for users to interact with data streamed in real-time. With the use of data-driven design, new social links are formed and powered by technology as the city becomes a digital public space.
M.S. in Architecture, December 2016
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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: RELATIVE RECEIVER AUTONOMOUS INTEGRITY MONITORING FOR FUTURE GNSS-BASED AIRCRAFT NAVIGATION
Creator: Gratton, Livio Rafael
Date: 2011-05-15, 2011-05
Description: The Global Positioning System (GPS) has enabled reliable, safe, and practical aircraft positioning for en-route and non-precision phases of...
Show moreThe Global Positioning System (GPS) has enabled reliable, safe, and practical aircraft positioning for en-route and non-precision phases of flight for more than a decade. Intense research is currently devoted to extending the use of Global Navigation Satellite Systems (GNSS), including GPS, to precision approach and landing operations. In this context, this work is focused on the development, analysis, and verification of the concept of Relative Receiver Autonomous Integrity Monitoring (RRAIM) and its potential applications to precision approach navigation. RRAIM fault detection algorithms are developed, and associated mathematical bounds on position error are derived. These are investigated as possible solutions to some current key challenges in precision approach navigation, discussed below. Augmentation systems serving large areas (like the Wide Area Augmentation System (WAAS) covering the North American continent) allow certain precision approach operations within the covered region. More and better satellites, with dual frequency capabilities, are expected to be in orbit in the mid-term future, which will potentially allow WAAS-like capabilities worldwide with a sparse ground station network. Two of the main challenges in achieving this goal are (1) ensuring that navigation fault detection functions are fast enough to alert worldwide users of hazardously misleading information, and (2) minimizing situations in which navigation is unavailable because the user‟s local satellite geometry is insufficient for safe position estimation. Local augmentation systems (to be implemented at individual airports, like the Local Area Augmentation System or LAAS) have the potential to allow precision approach and landing operations by providing precise corrections to user-satellite range measurements. An exception to these capabilities arises during ionospheric storms (caused by solar activity), when hazardous situations can exist with residual range errors several orders of magnitudes higher than nominal. Until dual frequency civil GPS signals are available, the ability to provide integrity during ionospheric storms, without excessive loss of availability, will be a major challenge. For all users, with or without augmentation, some situations cause short duration losses of satellites in view. Two examples are aircraft banking during turns and ionospheric scintillation. The loss of range signals can translate into gaps in good satellite geometry, and the resulting challenge is to ensure navigation continuity by bridging these gaps, while simultaneously maintaining high integrity. It is shown that the RRAIM methods developed in this research can be applied to mitigate each of these obstacles to safe and reliable precision aircraft navigation.
Ph.D. in Aerospace Engineering, May 2011
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Title: CLONING AND CHARACTERIZATION OF THE SNTA: NNOS: DYSTROPHIN INTERACTION SITES
Creator: Shi, Chenyue
Date: 2014, 2014-07
Description: Duchenne Muscular Dystrophy (DMD) is a lethal genetic disease caused by malfunction of the protein dystrophin. The main function of dystrophin...
Show moreDuchenne Muscular Dystrophy (DMD) is a lethal genetic disease caused by malfunction of the protein dystrophin. The main function of dystrophin is to connect the sarcolemma to the machinery of muscle function via specific binding domains near the C-terminus and N-terminus. These binding domains are connected by a large central rod region that had previously thought to have been biologically inert, but has recently been shown to contain binding sites for various biological partners, including a specific rod region that binds to nNOS, which is an important molecule in modulating vasodilation and increasing blood flow by relax vessel. Removal of this nNOS binding eliminates NO signaling during exercise, causing exercise-related ischemia leading to muscle damage. A major therapeutic strategy being studied to treat DMD is exon skipping, which results in modifications to the dystrophin protein. However, it remains unclear exactly where the binding sites on dystrophin protein and nNOS are, or how they interact with each other. This project is embarked upon more fully characterize the D1617 binding site on the nNOS PDZ domain. Previous studies show that, in neural tissue, PDZnNOS binds to two other proteins (PSD95 and N-methyl-D-aspartate receptor, NMDAR) forming a ternary complex in which the nNOS: PSD95 is a typical PDZ type interaction, but in which the nNOS :NMDAR binding occurred in an unusual fashion, through a unique “finger” region present in PDZnNOS but not in most other PDZ domains. Interestingly, in muscle cells, nNOS also interacts with two proteins, dystrophin and syntrophin (SNTA). Using this as an analogy, we hypothesize that in this case, the binding may also involve both the canonical and finger regions of PDZnNOS, one binding to each protein. We are testing this by constructing PDZnNOS variants with specific amino acid changes designed to xi disrupt each of these interactions (canonical and finger region) independently, and will then examine the impact on both the PDZSNTA and dystrophin D1617 interactions. It is hoped fully understanding the dystrophin nNOS interaction will allow therapies that require modification to dystrophin to conduct these modifications in a way that retains nNOS signaling required for proper muscle function.
M.S. in Cell and Molecular Biology, July 2014
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Title: MAXIMUM INDUCED SUBGRAPHS OF K-TREES WITH COMPONENTS OF ORDER 1 OR 2
Creator: Liu, Yunjiao
Date: 2014, 2014-07
Description: We study induced subgraphs where every component has order 1 or 2. For a graph G, let f(G) be the maximum order of such a subgraph of G....
Show moreWe study induced subgraphs where every component has order 1 or 2. For a graph G, let f(G) be the maximum order of such a subgraph of G. Chappell and Pelsmajer [1] considered a more general parameter for graphs G of bounded treewidth, but were unable to determine f(G) for graphs of treewidth k > 3, even asymptotically. They conjectured that f(G) ≥ ⌈ 2n k+2⌉ for an n-vertex graph of treewidth at most k, but for k > 3, they were only able to show that f(G) ≥ 2n+2 2k+3 . In this thesis, we improve the lower bound to l 8n 5(k+1)m, for n ≥ 2k + 1. In addition, for the case k = 4, we develop methods for an inductive proof, where the cases are verified by computer-checking. If the conjecture is false, then our approach should eventually lead to a counter-example. To facilitate this approach, we come up with the addition structure on 4-trees, where one K4-subgraph is the “root”, and we consider all the different ways that an induced subgraph can intersect with the root separately.
M.S. in Applied Mathematics, July 2014
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Title: INFEASIBILITY OF A POINTWISE TRUNCATION ERROR ESTIMATE TO DRIVE MESH ADAPTATION
Creator: Singh, Manpreet
Date: 2016, 2016-12
Description: An investigation of the Fast Approximation Scheme or FAS multigrid truncation error estimates at grid points with application to mesh...
Show moreAn investigation of the Fast Approximation Scheme or FAS multigrid truncation error estimates at grid points with application to mesh redistribution is presented. Feasibility of the error estimate as a means to adapt the mesh to a physical problem by solving the elliptic mesh equations derived from minimization of the error estimate based on the principle of equidistribution is examined by solving 1-D numerical test cases. To keep mesh movement under control, a parabolized version of the mesh equation is also tested to make an active comparison of the possible improvements in adaptivity and mesh quality. The results reveal smoothness issues indicating the need for a more robust estimator within the adaptive redistribution framework. Particularly, the prevalence of poor zonal e↵ects on the mesh points alone, point to lack of information over each cell thereby rendering the estimate ine↵ective to adapt the mesh.
M.S. in Mechanical Engineering, December 2016
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Title: Mycoflora of Indoor Dust and Alternaria Alternata Growth on Building Materials
Creator: Simpson, Stacy
Date: 2011-10-27, 2011-12
Description: Alternaria alternata, a clinically significant mold species is associated with allergic disease and asthma. An indoor growth of A. alternata...
Show moreAlternaria alternata, a clinically significant mold species is associated with allergic disease and asthma. An indoor growth of A. alternata may initiate atopic symptoms, accumulate in dusts, and discolor and deteriorate indoor building materials. Environmental control should be the initial approach to maintain a healthy indoor environment and manage allergic diseases. The current thesis investigated indoor dusts from various environments for mold spores and Alt a 1. Laboratory studies were carried out to determine if or which commercially available mold-resistant treatments and building materials could efficiently decrease A. alternata growth and Alt a 1. The mycoflora of indoor dusts was microscopically examined and the clinically significant allergen from A. alternata, Alt a 1 was measured in sampled dusts using a monoclonal anti-recombinant Alt a 1 (rAlt a 1) enzyme linked immuno-sorbent assay (ELISA). To investigate building material susceptibility untreated, mildew-resistant painted, and commercially available biocide treated building materials were inoculated with A. alternata spores, incubated in a humidity controlled chamber, and compared for mold growth and the presence of Alt a 1. A photo-monitoring technique was used to survey and determine mold growth surface area coverage. Alt a 1 immuno-reactivity of superficial mold growths was analyzed with the ELISA. The microscopic speciation of mold spores indicated that a diverse mycoflora can be found in indoor dusts. Although A. alternata was found in low concentrations in a few samples, Alt a 1was below the limit of detection. Nevertheless, mold spores can significantly contribute to the complexity of indoor dusts. A. alternata grew on all tested building materials but both painted and treated building materials inhibited mold growth in comparison to untreated samples. Not all material surfaces contained detectable levels of Alt a 1. Comparisons between untreated and painted building material groups indicated that a significant difference between the Alt a 1 accumulation content could not be established. To establish a standard sampling protocol and reliable prevention methods for mold contamination and exposure more knowledge about indoor molds must be gained.
M.S. in Environmental Engineering, December 2011
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Title: A POLYMORPHIC COMPUTING ARCHITECTURE BASED ON A DATAFLOW PROCESSOR CORE
Creator: Hentrich, David
Date: 2018, 2018-05
Description: Overall, this work provides an introduction to the subject of polymorphic computing, provides a new innovative polymorphic computer...
Show moreOverall, this work provides an introduction to the subject of polymorphic computing, provides a new innovative polymorphic computer architecture, and studies the architecture's performance with various test programs. The most important innovation of this work is the creation of an instruction set and computer architecture that allows individual instructions in an algorithm to be migrated in a fine-grained manner throughout a fabric of processors without the need for the algorithm to be aware of the underlying computer architecture. Essentially, the algorithms are independent of the underlying processing fabric and can be arbitrarily \draped" over the underlying processor fabric. Logically, this allows the computer architecture of the system to be modified under an algorithm. The intent of this is to create a system where the underlying computer architecture can be modified to improve the performance of an algorithm during runtime. The specific categories of contributions of this work are: 1. A definition of polymorphic computing, 2. A history of reconfigurable computing (the roots of polymorphic computing), 3. A description of relevant computer architecture concepts, 4. Case-studies of current polymorphic computing systems, 5. A new dataflow processor with performance monitoring features at the instruction and microarchitecture levels, 6. A new dataflow instruction set that contributes several advances to the field of dataflow instruction set design, 7. A polymorphic computing architecture based on the dataflow processor that allows programs to be migrated (\draped") across underlying cores in a fine- grained manner (i.e. on an instruction-by-instruction basis), 8. A description of how to write programs for the dataflow processor, 9. A number of programs written in the new instruction set for the dataflow processor/polymorphic computing architecture, 10. A performance evaluation of the ideal performance of the above programs in a single dataflow core, 11. A performance evaluation of a subset of the above programs in several polymorphic compute fabrics that were fine-grained placed (\draped") using a genetic search algorithm, 12. An iterative, deterministic algorithm for placing (\draping") functions in several polymorphic compute fabrics in a fine-grained manner based on runtime monitoring, 13. A performance evaluation of a subset of the above programs that were placed (\draped") in several polymorphic compute fabrics using the deterministic instruction placement algorithm, and 14. A comparison of the results between the genetic search instruction placement evaluation and the deterministic algorithm instruction placement evaluation.
Ph.D. in Computer Engineering, May 2018
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Title: MULTIFUNCTIONAL ELECTROCATALYST SUPPORTS AND ELECTROCATALYSTS FOR ELECTROCHEMICAL ENERGY CONVERSION
Creator: Kumar, Amod
Date: 2014, 2014-07
Description: Polymer electrolyte fuel cell (PEFC) technology has several underlying problems (lifetime, reliability and cost) that need to be resolved as a...
Show morePolymer electrolyte fuel cell (PEFC) technology has several underlying problems (lifetime, reliability and cost) that need to be resolved as a prerequisite for large-scale commercialization. Amongst these, the lifetime issue is regarded as critical. From the perspective of durability, the current state-of-the-art electrocatalyst, viz. platinum (Pt) supported on high surface area carbon, suffers substantial degradation during fuel cell operation. A key pathway for electrocatalyst degradation is the corrosion of the carbon support. During fuel cell startup and shutdown in automotive applications, the cathode potential undergoes excursions of up to 1.6 V. At these high potentials, the carbon corrosion reaction is significantly accelerated, leading to irreversible carbon loss at the electrode. The best way to eliminate the issue of support corrosion in PEFCs is to develop alternate corrosion-resistant catalyst supports. This dissertation investigates (i) mixed oxides of silica (SiO2) and ruthenia (RuO2) and (ii) tantalum modified titanium oxide (Ta0.3Ti0.7O2) for use as corrosion-resistant electrocatalyst supports in PEFCs, especially for the automotive sector, using detailed microstructure characterization and electrochemical evaluation, including two carefully chosen accelerated stress tests (startstop cycling to simulate fuel cell vehicle start-up and shut-down, and load cycling to simulate full-load to no-load transitions in the vehicle during operation). RuO2–SiO2 (0.5:0.5) displayed outstanding electrochemical stability upon exposure to rigorous accelerated potential cycling tests that mimic automotive drive cycles. The Pt/RuO2–SiO2 (0.5:0.5) electrocatalyst yielded a mass activity of 50 mA/mgPt and an area specific activity of 156.3 μA/cm2 at 0.9 V vs. RHE when tested in a fuel cell operating at 80 ºC and 75% RH. A 20 wt.% Pt/Ta0.3Ti0.7O2 catalyst was compared in terms of activity and stability against benchmark Pt/C catalysts. The importance of a corrosion resistant support in a PEFC was demonstrated by monitoring performance loss during start-stop cycling and load cycling; while load cycling did not cause a performance drop, the corrosion-resistant nature of the Ta0.3Ti0.7O2 support helped prevent catastrophic fuel cell failure observed in carbon-supported catalysts during start-stop cycling. Corrosion-resistant electrode materials can not only be applied to PEFCs but can also be extended to other electrochemical energy storage and conversion devices such as redox-flow batteries and electrolyzers. The results of this work also indicate suitable strategies for incorporation of other possible dopants (such as Nb, W and Zr) within TiO2, as well as the use of other metal oxides (such as SnO2 and HfO2) as alternative catalyst supports.
Ph.D. in Chemical Engineering, July 2014
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Title: AN INVESTIGATION INTO STABILITY OF TUBE AND COUPLER SCAFFOLDS SUBJECT TO SEISMIC LOADS
Creator: Najafabadi, Aram Zare
Date: 2012-11-23, 2012-12
Description: Temporary structures are structures that are set up for applications in relatively short time periods, most notably category of which are...
Show moreTemporary structures are structures that are set up for applications in relatively short time periods, most notably category of which are scaffolds that are built in two types: supported and suspended. Tube and coupler scaffolding systems are supported types and are commonly used in nuclear industry’s applications. This study evaluates the behavior of this type of scaffolding system due to the effect of dead, live, i.e. weight of workers and equipment, and lateral earthquake loads applied on the structure. Consistent with OSHA dimensional requirements, six different configurations ranging from 1 to 3 stories and 1 to 2 bay scaffoldings have been selected for this study. Using a finite element analysis, the significance of all gravity loads, as well as potential seismic loads on the safety and stability of aforementioned scaffold types was studied. The seismic acceleration level at which the failure occurs was determined for four failure criteria. These criteria are: (1) the structural member yield failure; (2) the structural member buckling failure; (3) the system sliding failure; and (4) the system overturning (tip-over) failure. The analysis results show that the most critical failure mode for all configurations of tube and coupler scaffolds studied in this thesis occurred due to instability and as result of sliding. No overstress or buckling failure was observed to occur prior or concurrent to this failure. This finding reaffirms that this type of scaffolds has considerable sufficient capacity to resist their intended loads yet are vulnerable to instability because of sliding. With regards to the effect of number of bays and stories on the critical earthquake level, it was observed that as the number of scaffold stories increases, the critical earthquake level becomes smaller except for the case of the 1-bay scaffold for the 2- and xii 3-story configurations. Addition of an extra bay to a simple 1-bay scaffold configuration does not considerably improve the earthquake level at which the sliding failure occurs. With regards to time of failure, addition of stories to a scaffold configuration delays the failure occurrence in all cases except for the case of the 2-bay scaffold and addition of a bay does significantly delay the occurrence of failure for 1- and 2-story scaffolds, about 6 second for 1-story scaffolds, and 8 seconds for 2-story scaffolds. However, this improvement is negligible for 3-story scaffolds. In general, addition of a bay postpones the failure time. The evaluation of stress levels in all various scaffolding elements suggests that increasing the number of bays and/or stories does not generally affect the induced stresses in beams. In addition, the study shows that buckling and overturning (uplift) effects have very minimal effect on the failure of tube and coupler scaffolds.
M.S. in Civil Engineering, December 2012
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Title: REGENERATIVE POTENTIAL OF HUMAN CD34+ STEM CELLS MOBILIZED AND ENRICHED FROM BONE MARROW
Creator: Cohen, Amy
Date: 2014, 2014-12
Description: This thesis provides an in-depth investigation of the heterogeneous population of CD34+ cells obtained through granulocyte-colony stimulating...
Show moreThis thesis provides an in-depth investigation of the heterogeneous population of CD34+ cells obtained through granulocyte-colony stimulating factor (G-CSF) mobilization, apheresis, and an immuno-magnetic selection process. The results provide a better understanding of the phenotypic characteristics, functional migratory capabilities and paracrine secretory performance when exposed to normal and low-oxygen environments in vitro. The overall composition of the population acquired through the cells selection process and the CD34+ cells were characterized for maturity and commitment to various cell types as well as their potential for migration, adhesion and proliferation. The detailed phenotypic characteristics included positivity for more primitive, undifferentiated hematopoietic stem cells (HSCs) as well as markers indicating enrichment of long term HSCs. A functional quantitative bioassay was used to measure the migratory ability of the CD34+ cells. On average, 18.7% of the CD34+ cells migrated after 3 hours of incubation in the presence of 200ng/mL of Stromal Cell-Derived Factor One alpha (SDF-1α) as compared to 0.6% of the CD34+ cells incubated without chemoattractant. The migration was successfully neutralized by using monoclonal antibodies to CXCR4 and a CXCR4 antagonist, AMD3100. An evaluation of the migratory cell population showed that the cells exhibited an enhanced commitment to a monocyte or lymphocyte lineage and a larger percentage were CXCR4+. CD34+ cells were incubated in normoxic and hypoxic conditions and the proliferation, viability, immunophenotypic profile, migratory potential and secreted cytokines were evaluated and compared to incubation in normoxic conditions. The CD34+ cells proliferated in both the normoxic and hypoxic conditions over three days of incubation. The proliferation was higher in the hypoxic condition after one day of incubation, but after three days of incubation the normoxic conditions resulted in more proliferation. An increase in CD164 and a decrease in CD99 in the Day 3 hypoxic condition suggest that hypoxia was stimulating an adhesion pathway and suppressing the functional migration of the CD34+ cells. The three hour hypoxia incubation resulted in a significant (63%) reduction in the migration of the CD34+ cells as compared to the 3 hour normoxia condition, but many of the cells continued to migrate in hypoxia over the 24 hour period while the normoxic cells continued to migrate, but at a much slower rate. Culture media from CD34+ stem cells that had been incubated in normoxic or hypoxic conditions for one day and three days was assayed for sixty cytokine proteins known for possessing angiogenic qualities. Twenty five angiogenesis cytokines were increased in the culture media incubated with CD34+ cells, including tissue inhibitor of metalloproteinases-1 and 2 (TIMP-1 and TIMP-2), angiopoietin-1 (ANG-1) and insulin-like growth factor-1 (IGF-1). Thirteen angiogenesis cytokines were elevated in hypoxia as compared to normoxia, including TIMP-1, IGF and growth-regulated oncogene-β (Gro-β).
Ph.D. in Biological and Chemical Sciences, December 2014
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Title: PUBLIC LITERACY ON SUSTAINABLE DEVELOPMENT
Creator: Panchal, Avani P.
Date: 2011-07-19, 2011-07
Description: Reports suggest that Chicago is one of the leading US cities with respect to sustainability and, in order to promote sustainability in a city...
Show moreReports suggest that Chicago is one of the leading US cities with respect to sustainability and, in order to promote sustainability in a city like Chicago, it is imperative that the residents are aware of factors associated with sustainable development and contribute towards its advancement. Majority of the research conducted so far, does not examine the non-expert level of sustainability understanding. This thesis investigates the public literacy on sustainable development by conducting a survey and analyzing the generated database. The statements posed in the survey do not demand technical education but assess the non-expert resident literacy of sustainability by asking relevant subjects. The survey consists of four demographic questions (participants‟ gender, age, level of education and annual income), fifteen conceptual statements and five opinion statements, based on sustainability. The aim is to find a relation, if any, between the respondents‟ demographics and their responses to the survey. The database generated from the survey of 353 randomly selected individuals, is analyzed by four different statistical methods, which are arranged in increasing order of complexity – (i) descriptive statistics and z-test for proportions, (ii) contingency tables and Pearson chi-square test, (iii) exploratory factor analysis and (iv) multinomial logistic regression. The outcome of the statistical analyses suggests that approximately 50% of the participants have accurately responded to the survey and the non-expert resident does not know the definitions to pertinent sustainability concepts. Additionally, survey responses have a strong association with the participants‟ age. There is a weak association between answers and the respondents‟ gender and annual income. In spite of higher than average participants with a college degree, the level of education has a negligible relation with survey responses. Thus, it is necessary to increase the awareness and educate non-experts about sustainable development. It is promising to observe that the responses to the opinion statements suggest that individuals are willing to contribute towards sustainability provided they are educated about it. Nonetheless, the willingness to contribute requires action and without societal support, it is not possible to promote sustainability, which requires increased understanding and knowledge and willingness to act appropriately.
M.S. in Environmental Engineering, July 2011
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Title: BINGE-DRINKING BEHAVIORS, ALCOHOL-RELATED CONSEQUENCES, AND HEALTH-RELATED QUALITY OF LIFE: DOES PSYCHOLOGICAL FLEXIBILITY PLAY A PART IN BINGE-DRINKING AND HEALTH BEHAVIORS OF COLLEGE STUDENTS?
Creator: Grix, Bethany
Date: 2014, 2014-07
Description: Binge-drinking among young adult populations is considered a global health and safety concern. Binge-drinking behavior has been directly...
Show moreBinge-drinking among young adult populations is considered a global health and safety concern. Binge-drinking behavior has been directly linked to immediate and long-term psychosocial, societal, and health-related consequences. To date, psychological flexibility and values-based committed action has been only theoretically linked to binge-drinking behavior, health, and alcohol-related consequences. Therefore, this study investigated binge-drinking behavior and its relationship with alcohol and health-related consequences, in a college-aged population, as well as the role psychological flexibility has within these relationships. Binge-drinking was defined as the consumption of ≥ 4/5 drinks (females/males, respectively), within a two hour period, over a 6-month period (NIAAA, 2004; Courney & Polnich, 2009). One hundred eighty-nine undergraduate participants (75 female, 114male) from a Midwestern university completed an online survey. Of the 189 undergraduates, 116 (61.4%) identified as non-binge-drinkers and 73 (38.6%) as binge-drinkers. Results showed that psychological flexibility predicted binge-drinking behavior. More specifically, higher degrees of psychological flexibility decreased the likelihood that individuals would engage in binge-drinking behavior. Interactions also emerged between binge-drinking quantity and psychological flexibility on alcohol-related consequences. Similarly, psychological flexibility was shown to buffer the relationship between binge-drinking status and HRQoL. Demographic and psychosocial differences also emerged across binge-drinking severity groups and outcome measures.
Ph.D. in Psychology, July 2014
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Title: THE DEVELOPMENT OF A CRYOGENIC OVER-PRESSURE PUMP
Creator: Alvarez, Matthew L.
Date: 2001-07-17, 2012-07
Description: The Dark Energy Survey (DES) project will study the accelerated expansion of the universe. In order to further study this phenomenon,...
Show moreThe Dark Energy Survey (DES) project will study the accelerated expansion of the universe. In order to further study this phenomenon, scientists have devised a method of creating an array of charged couple devices (CCD) to capture images that will be studied. These CCDs must be cooled and remain at 173K to eliminate thermal gradients and dark current. Therefore, a two-phase CCD liquid nitrogen (LN2) cooling system was designed to maintain the array of CCDs at a constant temperature. However, the centrifugal pump used to supply LN2 has a mean time between failure (MTBF) of approximately two thousand-eight hundred hours (116 days). Because of the low MTBF of the centrifugal pump, a new pump is being considered to replace the existing one. This positive displacement pump is a simpler design that is expected to have a MTBF that will exceed 116 days (2800hrs). This positive displacement reciprocating pump, also known as, the cryogenic over-pressure pump (OPP), was tested in February 2012 and successfully cooled the CCD array to 173K. Though un t for service for DES CCD cooling system, the overall concept of this pump has been proven. Typical ow rates, pressures, and temperatures trends have been captured via instrumentation and are speci c to the operation of future over-pressure pumps.
M.S. in Mechanical and Aerospace Engineering, July 2012
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