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Title: NEW TOOLS FOR JET ANALYSIS IN HIGH ENERGY COLLISIONS
Creator: Duffty, Daniel
Date: 2015, 2015-05
Description: Our understanding of the fundamental interactions of particles has come far in the last century, and is still pushing forward. As we build...
Show moreOur understanding of the fundamental interactions of particles has come far in the last century, and is still pushing forward. As we build ever more powerful machines to probe higher and higher energies, we will need to develop new tools to not only understand the new physics objects we are trying to detect, but even to understand the environment that we are searching in. We examine methods of identifying both boosted objects and low energy jets which will be shrouded in a sea of noise from other pasts of the detector. We display the power of boosted-b tagging in a simulated W' search. We also examine the effetc of pile up on low energy jet reconstructions. For this purpose we develop a new priority-based jet algorithm, "p-jets", to cluster the energy that belongs together, but ignore the rest.
Ph.D in Physics, May 2015
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Title: PIEZO-BARKHAUSEN PULSE SIGNAL ANALYSES (BPSA) AND DETERMINATION OF THE FATIGUE LIFE OF AISI-1018 STEEL NEAR THE ENDURANCE LIMIT
Creator: Nunez-moreno, Federico Alejandro
Date: 2014, 2014-05
Description: A series of fatigue tests were performed on two different types of steels named Steel A (annealed and decarbed AISI-1018 steel), and Steel B ...
Show moreA series of fatigue tests were performed on two different types of steels named Steel A (annealed and decarbed AISI-1018 steel), and Steel B (annealed and polished AISI-1018 steel), carried out to separation or to a maximum of 10,000,000 cycles (which was taken to be equivalent to infinite life). Strain levels ranging from 0.0014 in/in (0.0014mm/mm) down to 0.0008in/in (0.0008mm/mm) were used to execute all experimental load tests at a stress ratio R=-1 (complete reversal). An MTS machine was used for these trials. At the same time, magnetic fields and piezo-Barkhausen pulses were recorded by means of a flux gate magnetometer and a copper coil connected to a series of signal filters and amplifiers. Results were used to construct the classical S-N Whöler curve for both steels, as well as in exhibiting the behavior of the magnetic parameters (magnetic excursions, dominant frequencies of the magnetic signals) coupled to the fatigue lives of the samples tested. To describe such couplings, a set of correlations were introduced among the monitored variables as functions of testing time and applied strain. Also, a fractography analysis of the crack patterns using a scanning electron microscope was performed to represent statistically the geometry of “dimples” and fatigue striations from the inception of the crack, until the formation of a shear lip at the final stages of the crack. It was found that the magnitude of the mean amplitude of the piezo-Barkhausen pulses at early stages of the test is correlated to a mid-level energy of cracking, and thus explains the geometry of fatigue striations near the initiation of the crack at higher strain levels, compared to the geometry of the fatigue striations at lower strain levels. x xvi A joint analysis of the amplitudes of the magnetic excursions recorded in time, and the dominant frequencies of the magnetic signals were found to be discriminators of the elastic and plastic behavior of both types of steel. Furthermore the observed magnetic parameter variations determined in a clear way the endurance limit for each type of steel; these values also are in agreement with the strain level for which fatigue lives were greater than 10,000,000 cycles. Based on these results a “bell analogy” for interpreting the fatigue behavior is introduced. Bridge engineering applications and further research is also discussed.
PH.D in Civil Engineering, May 2014
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Title: CYBER-PHYSICAL SYSTEM FOR A WATER RECLAMATION PLANT: BALANCING AERATION, ENERGY, AND WATER QUALITY TO MAINTAIN PROCESS RESILIENCE
Creator: Zhu, Junjie
Date: 2015, 2015-07
Description: Aeration accounts for a large fraction of energy consumption in conventional water reclamation plants (WRPs). Although process operations at...
Show moreAeration accounts for a large fraction of energy consumption in conventional water reclamation plants (WRPs). Although process operations at older WRPs can satisfy effluent permit requirements, they typically operate with excess aeration. More effective process controls at older WRPs can be challenging as operators work to balance higher energy costs and more stringent effluent limitations while managing fluctuating loads. Therefore, understandings of process resilience or ability to quickly return to original operation conditions at a WRP are important. A state-of-art WRP should maintain process resilience to deal with different kinds of perturbations even after optimization of energy demands. This work was to evaluate the applicability and feasibility of cyber-physical system (CPS) for improving operation at Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) Calumet WRP. In this work, a process model was developed and used to better understand the conditions of current Calumet WRP, with additional valuable information from two dissolved oxygen field measurements. Meanwhile, a classification system was developed to reveal the pattern of historical influent scenario based on cluster analysis and cross-tabulation analysis. Based on the results from the classification, typical process control options were investigated. To ensure the feasibility of information acquisition, the reliability and flexibility of soft sensors were assessed to typical influent conditions. Finally, the process resilience was investigated to better balance influent perturbations, energy demands, and effluent quality for long-term operations. These investigations and evaluations show that although the energy demands change as the influent conditions and process controls, in general, aeration savings could be up to 50% from the level of current consumption; with a more xix complex process controls, the saving could be up to 70% in relatively steady-state conditions and at least 40% in relatively challenging transient conditions. The soft sensors can provide reliable and flexible performance on target predictions. The plant can still maintain at a similar level of process resilience after 50% aeration saving, even during long-term perturbations. Overall, this work shows that it is well feasible to provide more cost-effective operations at the Calumet WRP, and meanwhile influent perturbations, effluent quality, and process resilience are well in balance. Keywords: Energy, aeration, effluent quality, perturbation, resilience, water reclamation plant.
Ph.D. in Environmental Engineering, July 2015
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Title: NANOPORE STOCHASTIC SENSING OF BIOMARKERS IN HUMAN DISEASE
Creator: Zhou, Shuo
Date: 2016, 2016-07
Description: By measuring the ionic current modulation generated by analytes’ electro-osmotic flow through a nanoscale sized pore, nanopore stochastic...
Show moreBy measuring the ionic current modulation generated by analytes’ electro-osmotic flow through a nanoscale sized pore, nanopore stochastic sensing was invented about 20 years ago. Since then, it has been developed as a powerful and versatile tool for the detection of a wide variety of substances, including metal ions, organic molecules, DNA, RNA, peptides, proteins, etc. Compared with other traditional techniques such as immunochemical detection, colorimetric detection, HPLC, and GC/MS, nanopore detection has many advantages. First and foremost, nanopore stochastic sensing does not need to use sophisticated instruments which are convenient for people who do not have professional training in operating a special device. Furthermore, unlike fluorescent methods which rely on fluorophores labeling, nanopore stochastic sensing is a label-free detection method, which is based on the natural characteristics of analytes of interest. Moreover, nanopore sensing does not need complicated pretreatment of samples and can achieve a very low detection limit rapidly. Most importantly, nanopore detection uses only a small amount of sample with a low assay cost. In this dissertation, I summarize my work on nanopore stochastic sensing of proteases and copper ion, i.e., the detection of the HIV-1 protease (HIV-1 PR), trypsin, and copper ion. It is well-known that the HIV-1 protease is a significant biomarker for AIDS, while trypsin for the pancreatic disease. Considerable effort has been devoted to developing highly sensitive and selective sensors for these two important proteases. By taking advantage of nanopore stochastic sensing, two biosensors are constructed where picomolar concentrations of the HIV-1 protease and trypsin can be detected. On the other hand, copper, an essential trace element, is vital to the health of our human being in many ways. For example, the accumulation of cupric ions in human body may explain the origin of Wilson disease; further, the elevated concentration of copper is also pertinent to some symptoms of Alzheimer disease. Hence, the capability to the sensitive and accurate detection of copper ions is crucial to our health and well-being. For this purpose, a real-time and label-free nanopore biosensor is developed for its detection. The successful research efforts in these projects demonstrate the useful application of nanopore stochastic sensing in medical diagnosis, especially in terms of early disease detection. In addition to the high sensitivity and accuracy as well as low assay cost, other advantages of nanopore sensors include instrumental simplicity, ease of use, and extremely rapid data acquisition rates. Such a field-deployable nanopore sensor is useful as a point-of-care device for early disease detection and diagnosis. Just imagine how convenient your medical diagnosis would become with the pocket size nanopore sensor. We can monitor our own health anytime and anywhere: at home, at workplace, or even outside in remote and isolated places.
Ph.D. in Chemistry, July 2016
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Title: NEOVASCULARIZAnON WITHIN POROUS PEG HYDROGELS
Creator: Chiu, Yu-chieh
Date: 2011-11, 2011-12
Description: Development of engineered tissues of clinically relevant size requires the ability to control vascularization within biomaterial scaffolds....
Show moreDevelopment of engineered tissues of clinically relevant size requires the ability to control vascularization within biomaterial scaffolds. Poly(ethylene glycol) (PEG) hydrogels have been extensively investigated for use as synthetic scaffolds to support engineered tissue formation. The goal of this work described was to develop techniques that can be used to enhance vascularized tissue formation in PEG-based hydrogels. In the first part of the study a technique was developed to generate porous PEG hydrogels using a salt leaching technique. This technique was then used to examine the role of pore size on vascularization and tissue remodeling in porous PEG hydrogel in vitro and in vitro. Both in vitro and in vivo studies showed that vessel invasion was pore size dependent. In addition, a thin layer of inflammatory tissue was observed between PEG hydrogel and blood vessels that formed within the gels. This layer suggested that inflammatory cells, not vascular cells, interacted with the surface of the material. This suggests that peptides covalently incorporated within PEG may not directly interact with endothelial cells (ECs) following implantation. The porous PEG hydrogels were very stable in vitro and in vivo and did not exhibit any signs of degradation. Hydrogels used in tissue engineering need to exhibit controlled degradation. In order to address the stability of PEG hydrogels, porous hydrogels were rendered using degradable PEG-co-(L-Lactic acid) diacrylate PEG-PLLA-DA. This polymer is degraded via hydrolysis of the PLLA chains. The porous PEG-PLLA-DA hydrogels were generated by solvent casting, photopolymerization, and particulate leaching. The influence of polymer conditions on the architecture, degradation, and mechanical properties of the hydrogels were investigated in vitro. The hydrogels were found to exhibit autofluorescence that allowed for the unique ability to nondestructively image hydrogel structure under fully swelled conditions using confocal microscopy. Initial pore size was a function of particulate size and independent of polymer concentration. Interestingly, pore size remained stable though out the study, and was not a function of degradation. In addition, degradation time of porous PEG-LLA-DA hydrogels was influenced by polymer concentration. Compressive modulus was a function of polymer concentration and pore size and decreased during hydrogel degradation. The incorporation of cell adhesion sequences into the hydrogel showed that they can support cell adhesion with morphology varying with pore size. This technique could be used to tailor porous biodegradable scaffolds for tissue engineering applications. In the final portion of this thesis a poly-lysine (PLL) molecule was synthesized in order to allow clustering of adhesion sequences in PEG hydrogels. Clusters of peptide sequences have been shown to enhance cell interactions with substrate surfaces. The sequence was synthesized and purified by high performance liquid chromatography (HPLC) and characterized by mass spectrometry. The side chains of the PLL molecule was used to attach peptide sequences. Cysteine contained within the PLL allowed incorporation into the PEG hydrogel by mixed mode polymerization. Cells were observed to adhere to hydrogels containing the RGD clusters and not to the control gels. The results presented here describe various techniques that can be used to optimize the design of polymer scaffolds for tissue engineering. In addition, the data provide insight into the process of vascularization in porous hydrogels and the influence of synthesis conditions and degradation on properties of porous hydrogels. Future studies should investigate the optimization of these material techniques for control of neovascularization within PEG hydrogels for tissue engineering applications.
Ph.D. in Biomedical Engineering, December 2011
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Title: HOT DUCTILITY BEHAVIOR IN THE CONTINUOUS CASTING OF NIOBIUM-BEARING MICROALLOYED STEELS
Creator: Jansto, Steven George
Date: 2013, 2013-12
Description: Over 200 million tons of Niobium-bearing steels were continuously cast and hot rolled globally in 2012. These Nb-bearing plate, bar and sheet...
Show moreOver 200 million tons of Niobium-bearing steels were continuously cast and hot rolled globally in 2012. These Nb-bearing plate, bar and sheet products are manufactured throughout the world. The melting and casting practices to assure production of crack-free slabs, billets and blooms of high surface quality is presented. Much has been published about the traditional ductility trough associated with higher carbon equivalent steels with and without microalloy additions of Nb, V and/or Ti. The focus has primarily been on the chemistry and optimal composition based upon the literature review. However, the steelmaking and process metallurgy parameters are rarely correlated to the hot ductility behavior. Most studies involve laboratory produced heats, but this research is based upon industrial produced samples.The hot ductility troughs associated with simple carbon-manganese steels can also result in surface and internal quality issues if certain steelmaking and casting parameters are not followed. Although high carbon equivalent steels exhibit inherently lower hot ductility behavior, as measured by percent reduction in area at elevated temperature, these steels still exhibit sufficient ductility to satisfactorily meet the unbending stress and strain gradients existing in the straightening section of most casters. The % Reduction in Area significantly overstates the minimum ductility required for crack-free casting of Nb-bearing steels. The relationship between the steelmaking and caster operation and the resultant slab quality is related through the hot ductility behavior. This global Nb-bearing continuous casting steel research study introduces the strain energy as an improved xxi measure of the hot ductiity behavior. The incidence of cracking is primarily related to the steelmaking and caster process parameters and steel chemistry is secondary. These parameters include the elemental residual chemistry level, superheat variation, transfer ladle temperature stratification, oscillation frequency and stroke, mould flux incompatibility, casting speed fluctuation, and excessive secondary cooling.
PH.D in Materials Science and Engineering, December 2013
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Title: PRICING AND APPLICATION OF ELECTRIC STORAGE
Creator: Zhao, Jialin
Date: 2017, 2017-05
Description: Electric storage provides a vehicle to store power for future use. It contributes to the grids in multiple aspects. For instance, electric...
Show moreElectric storage provides a vehicle to store power for future use. It contributes to the grids in multiple aspects. For instance, electric storage is a more effective approach to provide electricity ancillary services than conventional methods. Additionally, electric storage, especially fast-responding units, allows owners to implement high-frequency power transactions in settings such as the 5-min real-time trading market. Such high-frequency power trades were limited in the past. However, as technology advances, the power markets have evolved. For instance, the California Independent System Operator now supports the 5-min real-time trading and the hourly day-ahead ancillary services bidding. Existing valuation models of electric storage were not designed to accommodate these recent market developments. To fill this gap, I focus on the fast-responding grid-level electric storage that provides both the real-time trading and the day-ahead ancillary services bidding. To evaluate such an asset, I propose a Monte Carlo Simulation-based valuation model. The foundation of my model is simulations of power prices. This study develops a new simulation model of electric prices. It is worth noting that, unlike existing models, my proposed simulation model captures the dependency of the real-time markets on the day-ahead markets. Upon such simulations, this study investigates the pricing and the application of electric storage at a 5-min granularity. Essentially, my model is a Dynamic Programming system with both endogenous variables (i.e., the State-of-Charge of electric storage) and exogenous variables (i.e., power prices). My first numerical example is the valuation of a fictitious 4MWh battery. Similarly, my second example evaluates the application of two units of 2MWh batteries. By comparing these two experiments, I investigate the issues related to battery configurations, such as the impacts of splitting storage capability on the valuation of electric storage.
Ph.D. in Management Science, May 2017
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Title: COMPUTATIONAL FLUID DYNAMICS AND POPULATION BALANCE MODEL FOR SIMULATION OF DRY SORBENT BASED CO2 CAPTURE PROCESS
Creator: Abbasi, Emadoddin
Date: 2013, 2013-12
Description: Carbon capture and sequestration (CCS) is one of the key technologies needed to mitigate carbon dioxide emission from industrial sources and...
Show moreCarbon capture and sequestration (CCS) is one of the key technologies needed to mitigate carbon dioxide emission from industrial sources and power plants. Development of CFD-based design tool for prediction of the extent of CO2 capture in a regenerable dry sorbent-based technology, in an efficient power plant design (i.e., modern IGCC power plants) was the driving force behind this project. In this study, we established a systematic methodology, starting from investigating the properties of the sorbent and its reaction mechanism, to developing a model for design and scale-up of the reactors that is needed to deploy this technology at larger scales. This dissertation provides a coupled CFD-PBE model based on the novel FCMOM approach with broad application in reaction engineering and reactor design where the polydisperse nature of the phases has strong effect on the hydrodynamics of the system. Detailed investigations of the MgO-based sorbent and its performance toward capturing CO2 from a coal gas stream were performed that result in development of the two-zone variable diffusivity shrinking core reaction model. Furthermore, a baseline design for a circulating fluidized bed (CFB) reactor, using numerical modeling and threedimensional simulations of a full-loop circulating fluidized bed reactor was provided based on the coupled CFD-PBE, which in combination with the reaction model can perform as a base for parametric studies and optimization of the process.
PH.D in Chemical Engineering, December 2013
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Title: AN INTRINSICALLY CONDUCTING POLYMER-BASED COATING SYSTEM FOR CORROSION PROTECTION OF STEELS
Creator: Yu, Qifeng
Date: 2016, 2016-12
Description: Among the various corrosion protection strategies for structural steels, coating techniques provide the most cost-effective protection and...
Show moreAmong the various corrosion protection strategies for structural steels, coating techniques provide the most cost-effective protection and have been used as the primary mode for corrosion protection. Existing coating techniques have been used mainly for their barrier capability and all have a limited service life. In this research work, a waterborne two-strand polyaniline: poly (acrylic acid) complex was synthesized and utilized to fabricate the primer layer of a two-layer coating system. The techniques of Scanning Kelvin Probe Force Microscopy (SKPFM) and Electrochemical Impedance Spectroscopy (EIS) were used to evaluate the anti-corrosion capability of the polymeric complex when mixed in an epoxy matrix and coated on steel samples as the primer layer. The evaluation results show that coating systems including a PANi-based primer has measurable anticorrosion capability and the anti-corrosion capability of PANi-based primer depends on the usage of PANi and the type of matrix material of the primer layer. In the laboratory condition, a prototype two-layer coating system including the PANi-based primer and a polyurethane topcoat was manufactured. The ASTM Salt-Spray Test and EIS were used to prove the anti-corrosion performance of the prototype using a two-layer, polyurethane-over-epoxy system (no PANi) as the control system. After the proof of concept, a non-waterborne epoxy was used to fabricate a different PANi-based primer. The two types of primers and two other commercial primers (a zinc-rich primer and an epoxy-only primer) were used to make a total of eight two-layer coating systems using two widely used topcoats. Salt-Spray Test, Cyclic Salt Fog/UV Exposure Test, Pull- Off Adhesion Test, and the techniques of EIS, SKPFM, and Scanning Electron Microscope (SEM) were used to evaluate the long-term performance of the eight systems. Based on the laboratory-based recommendations, six groups of two-layer coating systems were then subjected to the outdoor-exposure test to evaluate their anti-corrosion durability at two testing sites. The field durability of the coating systems was evaluated in terms of their surface gloss reduction, color change, adhesion change and surface deteriorations. The matrix material in which the PANi is mixed plays an important role in the longterm anti-corrosion performance of coatings. The waterborne epoxy is effective in dispersing PANi nano-particles and has zero VOC; however, it does not bond to the steel surface as strongly as the regular non-waterborne epoxy. The topcoat material also plays an important role in the long-term anti-corrosion performance of coatings; polyurethane has higher durability than epoxy as a topcoat material. The PANi-based systems possess long-term corrosion protection comparable to the performance of the conventional zincrich three-layer system based on the one-year field evaluation.
Ph.D. in Civil Engineering, December 2016
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Title: QUANTITATIVE ANALYSIS OF THE EFFECTS OF BIOFUNCTIONAL AND PHYSICAL GRADIENTS ON CELL BEHAVIOR IN POLY (ETHYLENE GLYCOL) DIACRYLATE HYDROGELS
Creator: Turturro, Michael
Date: 2012-10-29, 2012-12
Description: The continued enhancement of tissue engineered scaffolds relies on their ability to stimulate the formation of a stable microvascular network...
Show moreThe continued enhancement of tissue engineered scaffolds relies on their ability to stimulate the formation of a stable microvascular network within the biomaterial. In vivo, the spatial presentation of immobilized extracellular matrix cues and matrix mechanical properties play an important role in directed and guided cell behavior and neovascularization. The overall goals of this thesis are to develop a technique for the generation of gradients of physical properties and incorporated biofunctionality within poly(ethylene glycol) diacrylate (PEGDA) scaffolds and to investigate the effects of these gradients on 3D cell invasion and neovascularization. To this end, a novel photopolymerization technique for generating spatial variations in matrix properties and incorporated biofunctionality within synthetic PEGDA hydrogels, perfusion-based frontal polymerization (PBFP), was developed. This technique relies on the controlled perfusion of a photoinitiator to a reaction chamber containing a precursor solution and results in the propagation of a polymer reaction front that travels through the monomer solution creating a gradient in hydrogel crosslinking. Manipulation of the magnitude of the gradient can be achieved through alterations in the polymerization conditions. Scaffolds with embedded gradients were designed and optimized based on a range of properties shown to support 2D cell adhesion, proliferation, and 3D vascular cell invasion in bulk photopolymerized hydrogels with homogeneous properties. An in vitro model of neovascularization was used to evaluate the effect of these gradients on vascular sprout formation. Sprout invasion in gradient hydrogels occurred bi-directionally with sprout alignment observed in the direction parallel to the gradient while control hydrogels with homogeneous properties resulted in uniform invasion. In PBFP gradient hydrogels, sprout xvi length was found to be twice as long in the direction parallel to the gradient as compared to the perpendicular direction after three weeks in culture. This directionality was found to be more prominent in gradient regions of increased stiffness, crosslinked matrix metalloproteinase (MMP)-sensitive peptide presentation, and immobilized YRGDS concentration. In vivo tissue invasion was shown to be directly related to gradient properties and orientation. Alterations in the magnitude of the gradient in elastic modulus enhanced the directionality of invading vascular sprouts while restricting in vivo tissue invasion.
PH.D in Biomedical Engineering, December 2012
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Title: PSYCHOMETRIC PROPERTIES OF THE CENTER FOR EPIDEMILOGICAL STUDIES DEPRESSION SCALE (CES-D) USED AMONG NATIVE CHINESE INDIVIDUALS WITH SPINAL CORD INJURY
Creator: Xiong, Ying
Date: 2014, 2014-07
Description: Depressive symptoms are highly prevalent among people with Spinal Cord Injury (SCI) and yet there is a lack of consensus over psychometrically...
Show moreDepressive symptoms are highly prevalent among people with Spinal Cord Injury (SCI) and yet there is a lack of consensus over psychometrically sound diagnostic criteria or screening tools for depression. This is particularly true with the SCI population in China. Currently, there is limited information regarding the prevalence of depression, severity, and depressive symptomatology among individuals with SCI in China. CES-D lOis a simple and quick tool to use, and it avoids over-estimating depression due to frequent somatic complaints associated with SCI. To our best knowledge, the CES-D 10 had not been used among the native Chinese population with SCI. The current study used the CES-D 10 to measure depressive symptoms among individuals with SCI in China. The purpose ofthis study was to examine factorial validity, internal consistency, construct validity, and concurrent validity ofCES-D 10 among 260 Chinese individuals with SCI. Results showed an alarmingly high prevalence of depressive symptoms among the sample. Consistent with existing literature and hypotheses, a two-factor structure of CES-D 10 was replicated based on a confirmatory factor analysis. Hierarchical regression analyses showed several important psychosocial constructs such as acceptance of disability, social support, and functional disability were predictors of overall depressive symptoms. Surprisingly, depressive symptoms were not predictive of employment status. The scale showed low internal consistency, and a cultural response bias in which participants are less likely to endorse positively-stated CES-D items among the current sample. Such finding is consistent with past studies among the East Asian population. Limitations and implications ofthe study were discussed.
Ph.D. in Psychology, July 2014
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Title: CAPACITY BOUNDS FOR LARGE SCALE WIRELESS SENSOR NETWORKS
Creator: Tang, Shaojie
Date: 2012-11-20, 2012-12
Description: We study the network capacity of large scale wireless sensor networks under both Gaussian Channel model and Protocol Interference Model. To...
Show moreWe study the network capacity of large scale wireless sensor networks under both Gaussian Channel model and Protocol Interference Model. To study network capacity under gaussian channel model, we assume n wireless nodes {v1, v2, · · · , vn} are randomly or arbitrarily distributed in a square region Ba with side-length a. We randomly choose ns multicast sessions. For each source node vi, we randomly select k points pi,j (1 ≤ j ≤ k) in Ba and the node which is closest to pi,j will serve as a destination node of vi. The per-flow unicast(multicast) capacity is defined as the minimum data rate of all unicast(multicast) sessions in this network. We derive the achievable upper bounds on unicast capacity and a upper bound(partial achievable) on multicast capacity of the wireless networks under and Gaussian Channel model. We found that the unicast(multicast) capacity for wireless networks under both two models has three regimes. Under protocol interference model, we assume that n wireless nodes are randomly deployed in a square region with side-length a and all nodes have the uniform transmission range r and uniform interference range R > r. We further assume that each wireless node can transmit/receive at W bits/second over a common wireless channel. For each node vi, we randomly pick k − 1 nodes from the other n − 1 nodes as the receivers of the multicast session rooted at node vi. The aggregated multicast capacity is defined as the total data rate of all multicast sessions in the network. In this work we derive matching asymptotic upper bounds and lower bounds on multicast capacity of large scale random wireless networks under protocol interference model.
PH.D in Computer Science, December 2012
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Title: EMPIRICALLY KEYING PERSONALITY MEASURES TO MITIGATE FAKING EFFECTS AND IMPROVE VALIDITY: A MONTE CARLO INVESTIGATION
Creator: Tawney, Mark Ward
Date: 2012-12-05, 2012-12
Description: Personality-type measures should be viable tools to use for selection. They have incremental validity over cognitive measures and they add...
Show morePersonality-type measures should be viable tools to use for selection. They have incremental validity over cognitive measures and they add this incremental validity while decreasing adverse impact (Hough, 1998; Ones, Viswesvaran & Schmidt, 1993; Ones & Viswesvaran, 1998a). However, personality measures are susceptible to faking; individual’s instructed to fake on personality measures are able to increase their scores (Barrick & Mount, 1996; Ellingson, Sackett & Hough, 1999; Hough, Eaton, Dunnette, Kamp, & McCloy, 1990). Further, personality measures often reveal less than optimal validity estimates as research continually finds meta-analytic coefficients near .2 (e.g., Morgeson, Campion, Dipboye, Hollenbeck, Murphy, & Schmitt, 2007). Some researchers have suggested that these two problems are linked as faking on personality measure may reduce their ability to predict job performance (e.g., Tett & Christansen, 2007). Empirically keyed instruments traditionally enhance prediction and have been found to mitigate the effects of faking (Kluger, Reilly & Russell, 1991; Scott & Sinar, 2011). Recently suggested as a means to key to personality measures (e.g., Tawney & Mead, In Prep), this dissertation further investigates empirical keying methods as a means to both mitigate faking effects and as a means to increase validity of personality-type measures. A Monte Carlo methodology is used due to the difficulties in obtaining accurate measures of faking. As such, this dissertation investigates faking issues under controlled and known parameters, allowing for more robust conclusions as compared to prior faking research.
PH.D in Psychology, December 2012
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Title: TOWARDS THE EXACT CALCULATIONS OF THE FREE ENERGY FOR ENTANGLED SEMIFLEXIBLE POLYMER CHAIN
Creator: Pilyugina, Ekaterina
Date: 2015, 2015-05
Description: This work consists of two separate projects unified by the idea to extend the Discrete Slip-Link Model, which has been being successfully...
Show moreThis work consists of two separate projects unified by the idea to extend the Discrete Slip-Link Model, which has been being successfully developed in this group to predict rheological behavior of entangled flexible polymers, to new applications. The first project was dedicated to application of the Discrete Slip-Link Model to dielectric relaxation in order to simultaneously predict linear rheology and dielectric relaxation experiments of entangled polyisoprenes. Linear monodisperse, linear bidisperse and star-branched monodisperse systems were studied. It was found that all circumstances save one are well described. Namely, dilute long chains in a sea of short chains can be predicted rheologically, but dielectric relaxation data show a reduction in the relaxation time of long chains greater than that predicted by either the DSM or the expected Rouse motion. The second project was focused on the derivation of the exact free energy expression for semiflexible chains in the presence of entanglements in order to implement the DSM for semiflexible polymers. The special cases of chains with one, two and three strands are examined. An additional implementation of obtained results for one and two strands to buckling instability was performed. It is believed that in two dimensional case the critical buckling force is increased by thermal fluctuations in comparison to classical Euler buckling. However, how the critical buckling force is influenced by thermal fluctuations in three dimensions remains unclear. Some research groups calculate the critical buckling force approximately and conclude that, in opposite to 2D case, in 3D the force is decreased by thermal fluctuations. In this work the critical buckling force for semiflexible chain under compression was calculated exactly. It was shown that thermal fluctuations significantly increase the critical force over classical Euler buckling force in both two and three dimensions.
Ph.D. in Chemical Engineering, May 2015
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Title: URBAN SPRAWL AND SUSTAINABLE DEVELOPMENT IN CHINA
Creator: Wang, Xiaoxiao
Date: 2012-07-11, 2012-07
Description: Compared to the rich literature on urban sprawl in Western cities, relatively little is known of the driving factors, processes, and future...
Show moreCompared to the rich literature on urban sprawl in Western cities, relatively little is known of the driving factors, processes, and future trends of urban sprawl in China. This research will analyze the socio-economic forces behind two parts of urban sprawl in China: urban decentralization (the creation of development zones and new towns) and urban renewal (infrastructural changes to existing urban fabrics) and reveal two basic characteristic for Chinese urban sprawl: a). de-densification; and b). expansion of urbanized areas (urban built-up areas). This proposal aims to use the term “urban sprawl” to consider the reasons behind urban land-use changes and urban pattern transformations on a regional level. It begins with definitions of sprawl in Western and Eastern countries, and follows an analysis of the social, political, and cultural factors of sprawl. Three case studies will focus on three urban centers in China: Beijing, Shanghai, and Guangzhou. Still another component is data analysis with the program SPSS based on related Index for urban sprawl and sustainable development for 15 top urban regions in China during 10 years. This research has explored causes of urban sprawl in China: a). the changing residential preferences of some residents: willing to move out of the core; and b). overcrowded, deteriorated, and old-fashioned structures in central cities becoming targets for demolition in pursuing a new era of modernity, prosperity, and renaissance. Then, this research has pointed out: a). uneven land reform is the key to understand Chinese-style urban sprawl and it is also the necessary condition to the paradox posed by development zones and urbanized villages; b). China’s urban sprawl is driven by both market and government forces; and c). there are a series of new conditions for urban sprawl in China, for example: rising private automobile ownership, rising demand for space and changing residential preference, local public policy, and the real-estate industry. This research intends to provide a comprehensive definition of “urban sprawl” in China, identify the patterns of urban sprawl and growth in three urban regions (Beijing, Shanghai, and Guangzhou), and illustrate the concepts and possible alternative strategies for green urban growth and change in China. Finally, it will offer suggestions on how to effectively control urban sprawl in China, as well as provide a pathway to achieving sustainable development.
Ph.D. in Architecture, July 2012
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Title: INJECTION LOCKING BASED ULTRA LOW POWER RADIO FREQUENCY INTEGRATED CIRCUITS
Creator: Zhu, Qiang
Date: 2012-05-31, 2012-07
Description: Recent advances in radio frequency integrated circuit (RFIC) technology enable various innovative and versatile applications through ultra-low...
Show moreRecent advances in radio frequency integrated circuit (RFIC) technology enable various innovative and versatile applications through ultra-low-power wireless link such as mesh sensor network, personal area network (PAN) and semi-active RFID. This thesis introduces energy efficient demodulator and transceiver design for wireless communications. At the receiver front end, an ultra-low-power BPSK demodulator based on injection locked oscillators (ILOs) is introduced. Two second harmonic ILOs are employed to convert BPSK signals to ASK signals, which are then demodulated by an envelope detector to baseband. For sub-GHz applications, the ILOs are implemented using ring oscillators to allow compact chip area and ultra-low power dissipation. Bit error rate (BER) analysis of this demodulator indicates erroneous polarity flipping of demodulated bits due to phase noise of the ILO. The prototype chip is fabricated in a 65nm CMOS technology that consumes 228μW of power and occupies 0.014mm2 of die area. Measurement results reveal the demodulation of 750MHz 5Mb/s differential BPSK signal with a sensitivity of -43dBm. Theoretical BER analysis has been verified with erroneous flipping observed in the measurement and its probability close to the prediction. Then, an innovative injecting locking based transceiver architecture for ultra low power operation is proposed. It applied the ILO based BPSK demodulator at the receiver side. The oscillating signal at one receiver ILO also injects to another transmitter ILO for accurate carrier generation. Thus local frequency synthesis circuit which consumes considerable portion of power in traditional transceiver is not required. This design is implemented in a 45nm CMOS SOI technology. Measurement results indicate that the transceiver achieves downlink demodulation of -35dBm BPSK signal at 5Mb/s data rate and uplink transmission of -23dBm ASK signal at 1Mb/s data rate with 0.93mA current consumption from 1V power supply.
Ph.D. in Electrical Engineering, July 2012
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Title: A MULTI-CURVE LIBOR MARKET MODEL WITH UNCERTAINTIES DESCRIBED BY RANDOM FIELDS
Creator: Xu, Shengqiang
Date: 2012-12-19, 2012-12
Description: The LIBOR (London Interbank Offered Rate) market model has been widely used as an industry standard model for interest rates modeling and...
Show moreThe LIBOR (London Interbank Offered Rate) market model has been widely used as an industry standard model for interest rates modeling and interest rate derivatives pricing. In this thesis, a multi-curve LIBOR market model, with uncertainty described by random fields, is proposed and investigated. This new model is thus called a multi-curve random fields LIBOR market model (MRFLMM). First, the LIBOR market model is reviewed and the closed-form formulas for pricing caplets and swaptions are provided. It is extended to the case when the uncertainty terms are modeled as random fields and consequently the closed-form formulas for pricing caplets and swaptions are derived. This is a new model called the random fields LIBOR market model (RFLMM). Second, local volatility models and stochastic volatility models are combined with the RFLMM to explain the volatility skews or smiles observed in market. Closedform volatility formulas are derived via the lognormal mixture model in local volatility case, while the approximation scheme for the stochastic volatility case is obtained by a stochastic Taylor expansion method. Moreover, the above work is further extended to a multi-curve framework, where the curves for generating future forward rates and the curve for discounting cash flows are modeled distinctly but jointly. This multi-curve methodology is recently introduced lately by some pioneers to explain the inconsistency of interest rates after the 2008 credit crunch. Both LIBOR market model and RFLMM mentioned above can be categorized as models in singe-curve framework. Third, analogous to the single-curve framework, the multi-curve random fields LIBOR market model is derived and caplets and swaptions are priced with closedform formulas that can be reduced to exactly the Black’s formulas. This model is called a multi-curve random fields LIBOR market model (MRFLMM). Meanwhile, xii local volatility and stochastic volatility models are also combined with the multi-curve LIBOR market model to explain the volatility skews and smiles in the market. Fourth, the calibration of the above models is considered. Taking two-curve setting as an example, four different models, single-curve LIBOR market model, single-curve RFLMM, two-curve LIBOR market model and two-curve RFLMM are compared. The calibration is based on the spot market data on one trading day. The four models are calibrated to European cap volatility surface and swaption volatilities, given the specified parameterized form of correlation and instantaneous volatility. The calibration results show that the random fields models capture the volatility smiles better than non-random fields models and has less pricing error. Moreover, multi-curve models perform better than single-curve models, especially during/after credit crunch. Finally, the estimation of these four models, including pricing and hedging performance, is considered. The estimation uses time series of forward rates in market. Given a time series of term structure, the parameters of the four models are estimated using unscented Kalman filter (UKF). The results show that the random fields models have better estimation results than non-random fields models, with more accurate in-sample and out-sample pricing and better hedging performance. The multi-curve models also over-perform the single-curve models. In addition, it is shown theoretically and empirically that the random fields models have advantages that it is unnecessary to determine the number of factors in advance and not needed to re-calibrate. The multi-curve random fields LIBOR market model has the advantages of both multi-curve framework and random fields setting.
PH.D in Applied Mathematics, December 2012
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Title: ELECTROSPUN COLLAGEN/SILK TISSUE ENGINEERING SCAFFOLDS: FIBER FABRICATION, POST-TREATMENT OPTIMIZATION, AND APPLICATION IN NEURAL DIFFERENTIATION OF STEM CELLS
Creator: Zhu, Bofan
Date: 2017, 2017-05
Description: Biocompatible scaffolds mimicking the locally aligned fibrous structure of native extracellular matrix (ECM) are in high demand in tissue...
Show moreBiocompatible scaffolds mimicking the locally aligned fibrous structure of native extracellular matrix (ECM) are in high demand in tissue engineering. In this thesis research, unidirectionally aligned fibers were generated via a home-built electrospinning system. Collagen type I, as a major ECM component, was chosen in this study due to its support of cell proliferation and promotion of neuroectodermal commitment in stem cell differentiation. Synthetic dragline silk proteins, as biopolymers with remarkable tensile strength and superior elasticity, were also used as a model material. Good alignment, controllable fiber size and morphology, as well as a desirable deposition density of fibers were achieved via the optimization of solution and electrospinning parameters. The incorporation of silk proteins into collagen was found to significantly enhance mechanical properties and stability of electrospun fibers. Glutaraldehyde (GA) vapor post-treatment was demonstrated as a simple and effective way to tune the properties of collagen/silk fibers without changing their chemical composition. With 6-12 hours GA treatment, electrospun collagen/silk fibers were not only biocompatible, but could also effectively induce the polarization and neural commitment of stem cells, which were optimized on collagen rich fibers due to the unique combination of biochemical and biophysical cues imposed to cells. Taken together, electrospun collagen rich composite fibers are mechanically strong, stable and provide excellent cell adhesion. The unidirectionally aligned fibers can accelerate neural differentiation of stem cells, representing a promising therapy for neural tissue degenerative diseases and nerve injuries.
Ph.D. in Chemistry, May 2017
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Title: AUTOMATED PROGRESS CONTROL USING LASER SCANNING TECHNOLOGY
Creator: Zhang, Chengyi
Date: 2013, 2013-05
Description: Assessing progress in different construction activities at the end of every payment period is time consuming and requires specialized...
Show moreAssessing progress in different construction activities at the end of every payment period is time consuming and requires specialized personnel employed by the contractor and the owner. Automatic progress control that requires a minimum amount of human involvement could reduce the time spent on this activity, reduce the number of personnel used, reduce the cost involved, reduce disagreements between contractor and owner, and add to the overall efficiency of project management. Attempts have been made in the past to resolve this issue using image processing and other techniques but the results have not been satisfactory. A new attempt was made to set up a system that can assess progress control with minimum human input and the results are presented in this paper. The experiment made use of laser scanning technology and was conducted both in laboratory conditions and construction sites. The initial results from laboratory condition appear to be promising but there are still obstacles to surmount. The system is robust and accurate in laboratory conditions and constitutes proof of concept. Improvements are made to accelerate the registration process of multiple scans, to reduce the noise data, to recognize objects of irregular shape, and to assess the practicality and economic feasibility of such a system when applying this system in real construction sites. Keywords: Construction scheduling, progress control, laser scanning
PH.D in Civil Engineering, May 2013
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Title: SCALABLE RESOURCE MANAGEMENT SYSTEM SOFTWARE FOR EXTREMESCALE DISTRIBUTED SYSTEMS
Creator: Wang, Ke
Date: 2015, 2015-07
Description: Distributed systems are growing exponentially in the computing capacity. On the high-performance computing (HPC) side, supercomputers are...
Show moreDistributed systems are growing exponentially in the computing capacity. On the high-performance computing (HPC) side, supercomputers are predicted to reach exascale with billion-way parallelism around the end of this decade. Scientific applications running on supercomputers are becoming more diverse, including traditional large-scale HPC jobs, small-scale HPC ensemble runs, and fine-grained many-task computing (MTC) workloads. Similar challenges are cropping up in cloud computing as data-centers host ever growing larger number of servers exceeding many top HPC systems in production today. The applications commonly found in the cloud are ushering in the era of big data, resulting in billions of tasks that involve processing increasingly large amount of data. However, the resource management system (RMS) software of distributed systems is still designed around the decades-old centralized paradigm, which is far from satisfying the ever-growing needs of performance and scalability towards extreme scales, due to the limited capacity of a centralized server. This huge gap between the processing capacity and the performance needs has driven us to develop next-generation RMSs that are magnitudes more scalable. In this dissertation, we first devise a general system software taxonomy to explore the design choices of system software, and propose that key-value stores could serve as a building block. We then design distributed RMS on top of key-value stores. We propose a fully distributed architecture and a data-aware work stealing technique for the MTC resource management, and develop the SimMatrix simulator to explore the distributed designs, which informs the real implementation of the MATRIX task execution framework. We also propose a partition-based architecture and resource sharing techniques for the HPC resource management, and implement them by building the Slurm++ real workload manager and the SimSlurm++ simulator. We study the distributed designs through real systems up to thousands of nodes, and through simulations up to millions of nodes. Results show that the distributed paradigm has significant advantages over centralized one. We envision that the contributions of this dissertation will be both evolutionary and revolutionary to the extreme-scale computing community, and will lead to a plethora of following research work and innovations towards tomorrow’s extremescale systems.
Ph.D. in Computer Science, July 2015
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