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Title: MINIMIZING MAXIMUM PATH DELAY IN MULTIPATH CONNECTIONS
Creator: Devetak, Fabrizio U
Date: 2013, 2013-07
Description: Minimizing packet delay (or packet latency, as it is often called) is an impor- tant goal in modern telecommunication networks. In a network...
Show moreMinimizing packet delay (or packet latency, as it is often called) is an impor- tant goal in modern telecommunication networks. In a network with given physical and topological characteristics, uneven distribution of tra c between nodes may re- sult in parts of the network being underutilized while other parts may experience congestion and its related e ect of higher delays, and even packet loss if bu ers be- come overloaded. Overload results in longer queuing delays, which are a major, if not the major, source of packet delay. Internet nodes typically route based on a single best (shortest) path without taking into account link occupancy and without taking full advantage of all available network resources. So a method for improving network performance is to allow nodes to use multiple paths to route packets to a given desti- nation. In this research project the main objective is to nd the best algorithm that, applied to a multi-commodity network, produces multi-path ow assignments that minimize the maximum cross-network delay. The motivation for this objective is the tighter requirements for quality of service coming from real-time streaming services, such as voice and video, which restrict the maximum source-destination packet delay. An analytical approach, based on Lagrange Multipliers, was investigated which led to the design of an iterative algorithm that can be proved to converge to the opti- mal path and ow con guration. From that algorithm a simpli ed heuristic algorithm was derived, that achieves results close to optimal. Another heuristic but more intu- itive algorithm, similar to the algorithm described in [6], was also investigated and found to also o ers good results and to be computationally e cient. The two heuristic algorithms were simulated with Java programs and, as a benchmark, the single path algorithm that is commonly used in the Internet was also simulated. That simulation was also done with Java programs. Performance comparisons for the three types of simulations is also provided. For a more realistic evaluation, the intuitive heuristic algorithm was also simu- viii lated in the NS-3 simulation environment (in addition to the Java simulation). NS-3 is a state-of-the-art industry standard widely used in the academic world, and for it a distributed routing protocol, that implements the maximum delay minimization algorithms without centralized control, was designed.
PH.D in Computer Engineering, July 2013
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Title: SENTIMENT ANALYSIS BASED ON APPRAISAL THEORY AND FUNCTIONAL LOCAL GRAMMARS
Creator: Bloom, Kenneth
Date: 2011-08, 2011-12
Description: Much of the past work in structured sentiment extraction has been evaluated in ways that summarize the output of a sentiment extraction...
Show moreMuch of the past work in structured sentiment extraction has been evaluated in ways that summarize the output of a sentiment extraction technique for a particular application. In order to get a true picture of how accurate a sentiment extraction system is, however, it is important to see how well it performs at nding individual mentions of opinions in a corpus. Past work also focuses heavily on mining opinion/product-feature pairs from product review corpora, which has lead to sentiment extraction systems assuming that the documents they operate on are review-like | that each document concerns only one topic, that there are lots of reviews on a particular product, and that the product features of interest are frequently recurring phrases. Based on existing linguistics research, this dissertation introduces the concept of an appraisal expression, the basic grammatical unit by which an opinion is expressed about a target. The IIT sentiment corpus, intended to present an alternative to both of these assumptions that have pervaded sentiment analysis research, consists of blog posts annotated with appraisal expressions to enable the evaluation of how well sentiment analysis systems nd individual appraisal expressions. This dissertation introduces FLAG, an automated system for extracting appraisal expressions. FLAG operates using a three step process: (1) identifying attitude groups using a lexicon-based shallow parser, (2) identifying potential structures for the rest of the appraisal expression by identifying patterns in a sentence's dependency parse tree, (3) selecting the best appraisal expression for each attitude group using a discriminative reranker. FLAG achieves an overall accuracy of 0.261 F1 at identifying appraisal expressions, which is good considering the difficulty of the task.
Ph.D. in Computer Science, December 2011
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Title: REAL-TIME INTRUSION DETECTION FOR VOIP OVER WIRELESS NETWORKS
Creator: Tang, Jin
Date: 2012-07-16, 2012-07
Description: Voice over IP (VoIP) has emerged as a prevailing application in recent years. At the same time, with the increasing coverage of the IEEE 802...
Show moreVoice over IP (VoIP) has emerged as a prevailing application in recent years. At the same time, with the increasing coverage of the IEEE 802.11 based wireless networks, VoIP over wireless networks is drawing extensive attention in both academia and industry. Due to the openness and distributed nature of the protocols involved in VoIP over wireless, such as the session initiation protocol (SIP) and the IEEE 802.11 standard, it becomes easy for malicious users in the network to achieve their own gain or disrupt the service by deviating from the normal protocol behaviors. The main objective of this research is to develop real-time intrusion detection techniques that can quickly track down the malicious behaviors which manipulate the vulnerabilities from either VoIP or 802.11 protocols. Further, we will achieve the objective without requiring modification to the relevant standard protocols, and develop analytical tools to guide the detection system design for guaranteed performance. Specifically, for the malicious selfish misbehavior utilizing vulnerabilities of the 802.11 protocol, we design a real-time detector, termed as the fair share detector (FS detector), which exploits the non-parametric cumulative sum (CUSUM) test to quickly find a selfish malicious node without any a priori knowledge of the statistics of the selfish misbehavior. And while most of the existing schemes for selfish misbehavior detection depend on heuristic parameter configuration and experimental performance evaluation, we develop a Markov chain based analytical model to systematically study the FS detector. Based on the analytical model, we can quantitatively compute the system configuration parameters for guaranteed performance. Further, to achieve better detection performance, we enhance the FS detector to develop an adaptive detector with the Markov decision process (MDP). Then based on a reward function defined by us, we are able to determine an optimal decision policy to maximize the overall system benefit through a linear programming formulation. The optimal policy also indicates the operation of the adaptive detector, which yields better performance in both false positive rate and detection delay. For attacks on the SIP layer, we first focus on the well-known flooding attack and develop an online scheme to detect and subsequently prevent the attack, by integrating a novel three-dimensional sketch design with the Hellinger distance detection technique. Also, we address the stealthy attack, where intelligent attackers can afford long time to attack the system, and only incur minor changes to the system within each sampling period. To identify such attacks in the early stage for a timely response, we propose a detection scheme based on the signal processing technique wavelet, which is able to quickly expose the changes induced by the attacks. Moreover, we identify a new type of malformed message attack that can manipulate both the “Session-Expires” header in the SIP message and openness of wireless protocols to severely drain the network resources. We develop a detection method based on the Anderson-Darling test to deal with such attacks. In the future work, we will continue with the CUSUM-based framework for selfish misbehavior detection over practical multi-hop wireless networks with guaranteed performance. It is expected that we can generate distributed CUSUM-based detection mechanisms for the multi-hop networks, analytical tools for the distributed detection system, and configuration parameter selection methods for guaranteed detection performance. Moreover, as attackers can employ the openness of the 802.11 protocols to generate more severe and harder-to-detect attacks to the SIP based VoIP system, to further enhance the detection performance, we plan to develop cross-layer intrusion detection techniques for the system.
Ph.D. in Computer Engineering, July 2012
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Title: WIRELESS SENSOR NETWORK BASED BUILDING AUTOMATION SYSTEM
Creator: Yi, Peizhong
Date: 2012-07-11, 2012-07
Description: Smart grid adds intelligence and bidirectional communication capabilities to today’s power grid, enabling utilities to provide real-time...
Show moreSmart grid adds intelligence and bidirectional communication capabilities to today’s power grid, enabling utilities to provide real-time-pricing (RTP) information to their customers via smart meters. This facilitates customer participation in demand response programs to reduce peak electricity demand. ZigBee, as a wireless technology characterized by low cost, power, data rate, and complexity, is ideal for smart grid applications. Unfortunately, almost all ZigBee channels overlap with Wireless Local Area Networks (WLAN) channels, resulting in severe performance degradation. In this dissertation, firstly, practical ZigBee deployment guidelines under WLAN interference are presented. “Safe Distance” and “Safe Offset Frequency” are identified by means of a comprehensive approach consisting of theoretical analysis, software simulation, and empirical measurement. In addition, a frequency-agility based interference avoidance algorithm is proposed and is implemented. The proposed algorithm detects interference and adaptively switches nodes to “safe” channels dynamically to avoid interference with low latency and energy overhead. Later we propose a real-time residential demand response scheme based on price information provided by ZigBee enabled smart meters. We model the price signal as a random process with known deterministic components, and formulate the problem of cost-minimization as a stochastic scheduling problem. A constraint on the total power consumption is considered to avoid peak shifting. An opportunistic scheduling algorithm consisting of two stages is proposed. Each user is tentatively scheduled based on the optimal stopping approach as if there is no power constraint at the first stage, while the power constraint is taken into account at the second stage. The proposed scheduling algorithm can be implemented in either a centralized or distributed fashion. Simulations validate proposed scheme can evidently reduce the cost of electricity users. At last, an optimal and automatic residential load scheduling scheme with distributed storage system based on our price prediction scheme is proposed. The price prediction scheme forecasts the future 24-hour prices according to day-ahead pricing and RTP history. Our designed scheme adopts integer programming computation to provide simple solution for customers to minimize the total cost including electricity expenditure and storage degradation while satisfying customer time requirement. The performance of proposed scheme is then evaluated through simulation.
Ph.D. in Electrical Engineering, July 2012
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Title: MECHANISMS OF FOAMING, EFFECTS, PREVENTION, AND CONTROL IN ANAEROBIC DIGESTION
Creator: Subramanian, Bhargavi
Date: 2015, 2015-05
Description: Anaerobic digestion (AD) is an essential step to generate energy in the form of biogas from waste. Foaming during AD (AD foaming) is...
Show moreAnaerobic digestion (AD) is an essential step to generate energy in the form of biogas from waste. Foaming during AD (AD foaming) is widespread phenomenon and leads to deterioration of the AD process and operation. In extreme conditions, AD foaming poses a significant safety risk and considerable economic impacts. It is, therefore, necessary to understand the fundamentals of AD foaming to develop effective strategies that can help minimize and prevent the foaming impacts. Several aspects of AD foaming have attracted considerable research attention, however, the focus has been mainly on site specific causes and prevention. The work leading to this thesis was aimed to provide a better understanding of the AD foaming problem, to identify the underlying mechanisms, causes and contributors of foaming and to come up with foam management strategies for full-scale plants. Full-scale cylindrical digester investigations did not identify non-biological factors such as organic loading rate (OLR), mixing, and primary to waste activated sludge (PS:WAS) solids ratio as primary causes of foaming, but foam-causing filaments such as G. amarae and M. parvicella were determined to be primary causes. No foaming was observed over the duration of the study, indicating absence of a primary foaming cause even though the suspected contributors to AD foaming were present. In the case of full-scale egg-shaped digesters (ESD), foaming and foam collapse events were observed over the duration of the study over both during filamentous foaming and non-foaming seasons, indicating that the primary foaming cause requires the contributors to be present. The results of this study demonstrate that ESDs foamed due to high mixing and G. amarae counts above the threshold level (log #6 intersections/mg VSS) in mixed liquor. In both types of digesters, total solids and temperature profiles showed that reducing mixing frequency did not significantly impact digester performance or the homogeneity of the digester contents. Hence, mixing intensity optimization could be an effective strategy in addition to primary cause reduction of foam causing filaments.
Ph.D. in Environmental Engineering, May 2015
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Title: Informal Settings: Implications for Secondary Mathematics Teachers' Abilities to Recognize and Apply Mathematics
Creator: Popovic, Gorjana
Date: 2011-08, 2011-07
Description: The purpose of this study was to describe the ways in which situating learning experiences for mathematics teachers in informal sites,...
Show moreThe purpose of this study was to describe the ways in which situating learning experiences for mathematics teachers in informal sites, specifically in the science museum, assist them in recognizing mathematics in the real world and developing instructional math to help their students make connections between school mathematics and its real world applications. The study took place in the Museum of Science and Industry (MSI), in Chicago, IL. Seven teachers (six female and one male) certified by their state to teach secondary mathematics (grades 6-12), pursuing a Masters in Mathematics Education degree at a private Midwest university, volunteered to participate in the study. Ethnographic methods (e.g., audiotapes of instruction, students’ written work) of data collection and analysis were used to capture teachers’ learning in the context of MSI exhibits (Lave, 1988). Lave’s methodology considers “person-acting (in setting) as an integral unit of analysis” (Lave, 1988, p. 180). Accordingly, the data collection and analysis were organized around two tasks: identifying mathematical concepts represented in the exhibits and creating lesson ideas to address identified mathematical concepts. The data collection included audiotapes of the group discussions around the exhibits, teachers’ Mathematics Concepts and Curriculum Connections (MC3) cards, and teachers’ reflections papers completed at the end of the study. The process of data analysis consisted of multiple interpretative passes through the data. An ethnographically grounded approach to discourse analysis (Gee and Green, 1998) was used as a framework for the analysis across data types. viii The results of the study showed that over the course of the study, teachers began to change their approach to identifying mathematics in the exhibits in two ways. In particular, the teachers realized that the obvious representations of mathematics, such as the appearance of numbers, geometric shapes and geometric figures in the exhibits were not vital to identifying mathematics. Additionally, teachers began to realize that learning about mathematical concepts could be done through exploration of scientific phenomena. The results also showed that once the teachers recognized mathematical concepts in an informal site, they were able to create lessons to address those concepts, as well as to identify where in the curriculum they could use the activities to enhance students’ learning. However, the support of the school administration and curriculum is necessary in order for teachers to incorporate informal education applications into their mathematics instruction.
Ph.D. in Mathematics Education, July 2011
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Title: MICRO-SCALE EHD CONDUCTION-DRIVEN PUMPING AND HEAT TRANSFER ENHANCEMENT IN SINGLE- AND TWO-PHASE SYSTEMS
Creator: Pearson, Matthew
Date: 2011-04-19, 2011-05
Description: Electrohydrodynamic (EHD) pumping methods rely on the interaction between electric fields and the flow fields of a dielectric fluid....
Show moreElectrohydrodynamic (EHD) pumping methods rely on the interaction between electric fields and the flow fields of a dielectric fluid. Conduction pumping is one EHD pumping mechanism, which offers many advantages over other EHD pumping methods (for example, a simple design, no degradation of the working fluid, and no need for a temperature gradient). Conduction pumping can be used in an adiabatic context to pump a working fluid or it can be applied to deliver substantial enhancement to single- and two-phase heat transfer processes. Experimental studies of conduction pumping to date have focused on macro-scale devices with applied voltages on the order of 10 kV. However, like many other EHD concepts, conduction pumping depends primarily on the intensity of the imposed electric field. Therefore, at the micro-scale, the reduced physical size can be accompanied by a reduction in the magnitude of the applied voltage to levels that are significantly more manageable. Furthermore, the simplicity of EHD conduction pumps, such as the lack of moving parts, high reliability, and physical compactness, make them an attractive method for pressure generation in micro-scale fluid and heat transfer devices. This experimental study examines the fundamental behavior and performance of EHD conduction pumping at the micro-scale. The pump is embedded in a rectangular, adiabatic micro-channel, and the single-phase flow and pressure generation of the pump are characterized. The EHD pumping of single- and two-phase flows in micro-channels in the presence of heat transfer is also studied and the corresponding enhancement to single- and two-phase heat transfer is quantified. In an additional study, micro-scale electrodes are embedded within a flat, heated surface to examine the ability of the conduction pump to provide electrically-enhanced wetting of the heated surface during pool boiling. A model based on hydrodynamic instability theory is generated to quantify the influence of the EHD conduction pumping on the pool boiling critical heat flux. Finally, this technology is incorporated into two unique, novel, heat transport devices akin to a heat pipe but in which the primary driving force for the liquid is conduction pumping, not capillarity.
Ph.D. in Mechanical and Aerospace Engineering, May 2011
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Title: DIGITAL CONTROL OF 2-QUADRANT AND 4-QUADRANT SWITCHED RELUCTANCE MOTOR DRIVES
Creator: Shao, Baiming
Date: 2011-04-19, 2011-05
Description: Switched reluctance machines (SRMs) are attractive because of their manufacturing simplicity and high reliability. They do not have any...
Show moreSwitched reluctance machines (SRMs) are attractive because of their manufacturing simplicity and high reliability. They do not have any windings or permanent magnets on the rotor, which makes them robust and easy to maintain. On the other hand, SRMs are highly non-linear since they work in saturation. This causes problems such as high torque ripple and system noise. In addition, mutual inductance needs to be considered for the high performance systems such as electric vehicle or aerospace applications. This effect could become critical when more than one phase is conducting. This also makes them difficult for modeling and control. Significant research on different SRM control techniques has been done in order to improve the performance of the controller and present a good solution for the industrial applications with a reasonable cost. Conventional control techniques for SRMs include chopped current control (CCC), angular position control (APC), and pulse-width modulation (PWM). Proportional-integral (PI) and other linear controllers are also used in the drive systems. However, because of the non-linearity of the machine, classic linear control techniques are not ideal for SRMs as they have challenging control issues in wide speed ranges. Different methods have been presented to implement non-linear control techniques for SRM drives or linearize the SRM motor equations. Many SRM controllers are using one or more look-up tables. The behavior of the controller is adjusting in real-time depending on the data in the look-up tables. This could increase the cost and complexity of the system. In this Ph.D. dissertation, an advanced digital control concept is presented for SRMs in both motoring and generating modes. By treating the system digitally, the controller switches between two pre-defined states to get the desired output. The proposed control technique does not need any look up tables, is not sensitive to the motor parameter variations, is low cost, and has a wide speed range. Simulation and experimental results are presented to verify the proposed digital control approach.
Ph.D. in Electrical and Computer Engineering, May 2011
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Title: EXECUTIVE FUNCTION AND DEPRESSIVE SYMPTOMS IN PATIENTS WITH ISCHEMIC STROKE
Creator: Marola, Jennifer
Date: 2013, 2013-07
Description: Previous research has demonstrated impairment following stroke, including depressive symptoms (Herrmann et al., 2011; O'Brien et al., 2003;...
Show morePrevious research has demonstrated impairment following stroke, including depressive symptoms (Herrmann et al., 2011; O'Brien et al., 2003; Robinson, 2006; Robinson & Spalletta, 2010; Teper & O'Brien, 2008) and cognitive impairment, particularly in executive function (Canning, Leach, Stuss, Ngo, & Black, 2004; Carew, Lamar, Cloud, Grossman, & Libon, 1997; Garrett et al., 2004; Kertesz & Clydesdale, 1994; Lafosse et al., 1997; Madureira, Guerreiro, & Ferro, 2001; Padovani et al., 1995; Su, Lin, Kwan, & Guo, 2008). Current research is limited by the use of primarily patients in the hospital with multiple types of stroke and physical impairment. Additionally, a conceptualization of executive function by Stuss and colleagues (Stuss, Shallice, Alexander, & Picton, 1995) has not been thoroughly investigated utilizing factor analytic techniques. The current study attempted to expand research on executive function and depressive symptoms in individuals with ischemic stroke. This study examined performance on measures of executive function, memory, language, and visuospatial ability, along with measurement of depressive symptoms in participants with ischemic stroke and healthy matched control participants. Results revealed that participants with stroke performed significantly worse in all cognitive domains than control participants. More specifically, in participants with stroke, executive function was more impaired than memory, language, and visuospatial ability. A regression analysis did not find that depressive symptoms accounted for additional variance in executive function above x demographic factors. Two and three factor models of executive function were not supported; the data more closely resembled a one factor model of executive function.
PH.D in Psychology, July 2013
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Title: THE RELATIONSHIP BETWEEN ACCULTURATION AND HELP SEEKING ATTITUDES AND BEHAVIOR OF ASIAN INDIANS IN THE UNITED STATES
Creator: Beri, Reema S.
Date: 2012-04-22, 2012-05
Description: The Asian Indian population in the United States continues to expand rapidly. At the same time, little research exists that has examined the...
Show moreThe Asian Indian population in the United States continues to expand rapidly. At the same time, little research exists that has examined the overall mental health needs of this group or how their level of acculturation affects their help seeking attitudes and behaviors. Research on Asian Americans (of which Asian Indians are a sub-group) that has assessed how acculturation affects help seeking attitudes and utilization behavior has yielded inconsistent results. One possible explanation for the discrepant findings may be due to the way acculturation has been conceptualized and measured. Specifically, most studies have measured acculturation unilinearly, while current research shows that acculturation may be best measured as a bilinear construct. The purpose of the present study was to assess the influence of acculturation on the help seeking attitudes and professional utilization behavior of Asian Indians living in the United States using a bilinear measure of acculturation. The study sample consisted of 266 Asian Indians currently living in the United States. Acculturation was assessed bilinearly using the Asian American Multidimensional Acculturation Scale (AAMAS; Chung, Kim & Abreu, 2004), that allowed for classification into one of four acculturation groups: integrated, assimilated, separated, and marginalized. Help seeking attitudes was measured using the Inventory of Attitudes Toward Seeking Psychological Services (IASMHS; Mackenzie, Knox, Gekoski & Macaulay, 2004), and a demographic questionnaire assessed utilization behaviors and participants’ backgrounds. Results indicate that integrated and assimilated individuals demonstrated more positive help seeking attitudes than separated and marginalized individuals, while no difference was found among the groups in terms of their professional utilization behavior. Implications of the findings and suggestions for future research are discussed.
Ph.D. in Psychology, May 2012
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Title: TEMPERAMENT AND PARENTING: DO THEY INFLUENCE EACH OTHER AND SOCIAL COMPETENCE?
Creator: Strickland, Jennifer Pierce Munson
Date: 2012-04-19, 2012-05
Description: The aim of this study was to examine the reciprocal relationship between parenting behaviors (support, hostility, and scaffolding) and child...
Show moreThe aim of this study was to examine the reciprocal relationship between parenting behaviors (support, hostility, and scaffolding) and child temperament (effortful control, EC, and negative affect, NA) in children during the transition from kindergarten to first grade. Another aim was to examine direct and indirect effects of parenting and child temperament on children’s social competence. Participants included a diverse, community sample of 580 children and their primary caregivers. Parent support and hostility were assessed with the Parent Behavior Inventory. Scaffolding was assessed with observer ratings based on the NICHD ECCRN 3-Boxes Task. Child NA and EC were measured by parent-report using the Child Behavior Questionnaire, and social competence was assessed with the Social Skills Rating System. All measures were administered at both ages. Results indicated that the model that included cross-paths between the parenting and child factors provided the best fit to the data. The path coefficients indicated that child EC had significant effects on parenting behaviors (support, hostility and scaffolding). Contrary to expectation, however, there were no significant paths from parenting to child temperament. Both child EC and parenting support had significant direct and indirect effects on child social competence. Implications of the findings and suggestions for future research are discussed.
Ph.D. in Psychology, May 2012
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Title: TOPICS IN STATISTICAL MODELING AND OPTIMAL DESIGN
Creator: Li, Yiou
Date: 2014, 2014-07
Description: In this dissertation we discuss several topics in statistics concerning regression models, experimental design and optimization. When it is...
Show moreIn this dissertation we discuss several topics in statistics concerning regression models, experimental design and optimization. When it is expensive to compute a function value via numerical simulation, obtaining gradient values simultaneously can improve model e ciency. In the rst and second parts, polynomial regression models with gradient information are considered. We propose an orthogonal polynomial basis with respect to an inner product involving gradients of functions, to eliminate the illconditioning of the design matrix caused by Hermite polynomial basis. Through a simpli ed nuclear reactor model, we show that compared with Hermite polynomial basis, the orthogonal polynomial basis results in a better-conditioned design matrix, and a signi cant improvement when basis polynomials are chosen adaptively, using a stepwise tting procedure. In the second part, the design problem for polynomial regression models with gradient information is addressed. A theoretical upper bound is derived on the scaled integrated mean squared error in terms of the discrepancy of the design, and this bound can be used to choose designs that are both e cient and robust under model uncertainty. Numerical experiments show that low discrepancy designs, whose empirical distribution functions match a xed target distribution, outperform random and Latin hypercube designs. Considering a speci ed regression model, we propose a relaxed optimization problem, which is a semide nite programming problem, to nd the optimal design that minimizes scaled integrated mean squared error. Numerical examples demonstrate the eligibility of the method by showing that the optimal designs we achieve coincide with the already known optimal designs for regression model without gradient information. In the third part of the dissertation, the optimal layout of wind farm is considered. To maximize the expected annual pro t gained by the wind farm, we seek for both optimal number of wind turbines and optimal positions of wind turbines based on Jensen's model. Wind speed and direction are considered as random variables with distribution approximated by empirical distribution from real data. We propose using particle swarm optimization to solve for the optimal layout of wind farm. At last, the situation that more wind turbines are added to an existing wind farm is discussed.
Ph.D. in Applied Mathematics, July 2014
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Title: International Bond Portfolio: Evidence from Emerging Markets
Creator: Wang, Jinghua
Date: 2012-08-20, 2012-07
Description: Allocating capital to fixed income instruments issued by emerging markets (EMs), governments may provide significant benefits to both the...
Show moreAllocating capital to fixed income instruments issued by emerging markets (EMs), governments may provide significant benefits to both the investors and issuers of these instruments. For investors, emerging market instruments may offer a significant risk premium relative to conventional investments in developed markets (DMs) bonds. Furthermore, EMs bonds offer potential diversification benefits because these bonds are not strongly correlated with DMs instruments. For emerging market government issuers, access to global fixed income markets is likely to improve liquidity and offer lower borrowing costs relative to a strategy focused purely on the domestic market. Access to global capital provides these governments with the opportunity to invest in infrastructure projects that promote economic growth and development. Over the past fifty years, economic growth in emerging markets has been supported by investments in capital and technology from the developed world. The benefit of this development for the emerging markets, as measured by growth in income, employment, and wealth, is immediately apparent. There have also been significant advantages for the developed world through opportunities for higher risk adjusted returns from investments in emerging markets. For the most part, the benefits of diversification into emerging markets have focused on equity markets. In this dissertation, the focus is on investments in fixed income instruments. Specifically, the dissertation explores the performance benefits of DMs combined with EMs. It first identifies the potential diversification and describes the financial integration for incorporating EMs bonds into DMs government bond portfolios. In the second phase, it constructs the dynamic linear regression models and conducts the mean-variance tests to demonstrate the incremental benefit of the strategy. In the last phase, a robust test examines the strength of bond portfolio performance between DMs with EMs and the U.S. 7-10 year government bond index. The empirical analysis in this dissertation focuses on three DMs sources of bonds and four EMs regions. Since the EMs are evolving rapidly, and since the global financial markets have also been subject to erratic fluctuations during the global financial crisis, the empirical models employed in the dissertation do not rely on stationarity assumptions. Instead, Kalman Filter (KF) procedures are employed that generate the time-varying coefficients in the multi-factor models in response to new conditions in the markets. The outputs from the KF are used as inputs in the factor model, and the outputs from the factor models are used as inputs in a Markowitz style mean-variance optimization model. This study explores the benefits of the diversification of global government bond portfolio, and provides complete performance evaluations of DMs with or without EMs. The study examines: i) the benefits of inclusion of EMs bonds in DMs; ii) the degrees of financial integration among the research markets; iii) the correlation of the macro-economic factors in the multi-factor models; iv) the relative bond returns of dynamic factor models with time-varying coefficients; and v) the robust tests of bond portfolio performance between DMs with EMs and bond index. The results of this study provide important implications for global investors by identifying diversification gains in EMs.
Ph.D. in Management Science in Finance, July 2012
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Title: A STRUCTURAL ANALYSIS FRAMEWORK FOR CONCRETE FACED ROCKFILL DAMS
Creator: Quiroz, Juan E.
Date: 2013, 2013-12
Description: Concrete Faced Rockfill Dams (CFRD’s) are commonly built around the world. As energy demands soar and construction methods evolve, the...
Show moreConcrete Faced Rockfill Dams (CFRD’s) are commonly built around the world. As energy demands soar and construction methods evolve, the interest for construction of CFRD’s with larger heights has increased tremendously. However, because of construction of higher CFRD’s, some dams have experienced considerable fractures at the concrete faces. Well known cases include Campos Novos (Brazil), Barra Grande (Brazil), and Mohale (South Africa), where in some instances these cracks have led to dewatering of the reservoir to allow for the concrete slabs repairs. The development of these fractures may be attributed to the highly deformable rockfill body. In general, the state-of-the-art design of CFRD’s is mostly based on common practice rather than rigorous analysis procedures. And as such, cracking problems because of deformability of the rockfill may not be properly predicted unless a detailed analysis is performed. In this work, a new framework for analysis of CFRD’s is developed that is capable of predicting the possible concrete-facing failure. As a part of this framework, a comprehensive non-linear finite element analysis (FEA) scheme is developed to model the construction sequence, the contact interaction between the concrete facing and the rockfill body, and the impounding of the reservoir. As a case study, using the developed framework, the Kárahnjúkar CFRD (Iceland, 198m height) is analyzed, the results are validated by the field measurements, and mitigation measures suggestions are provided. This methodology, based on the results of the investigation, provides guidelines and establishes a framework for analysis of CFRD’s that can be used for design purposes.. Keywords: CFRD, Concrete Faced, Rockfill, Dam, Finite Element Analysis.
PH.D in Structural Engineering, December 2013
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Title: THE STRUCTURAL AND MAGNETIC STABILITY OF SELECT FERROUS HEUSLER SYSTEMS
Creator: Hasier, John J.
Date: 2017, 2017-05
Description: Heusler based functional or smart materials are a deep well of solutions to future energy, heat transport and mechanization problems. The half...
Show moreHeusler based functional or smart materials are a deep well of solutions to future energy, heat transport and mechanization problems. The half-metallic ferromagnetic nature of these crystalline intermetallic compounds is the source of their extraordinary properties. The loss of this magnetic ordering places limits on the range of application temperatures making knowledge of the Curie point of these novel materials essential for understanding of their limitations. High throughput continuous wavelet transform spectrum analysis of magnetic balance data generated on a custom modified Setaram Setsys Evolution 16/18 Differential Scanning Calorimeter- Differential Thermal Analyzer with simultaneous Thermogravimetric Analyzer was performed on select Fe, Co and Mn based Heusler compounds. The phase stability of Co-Fe-Si compounds is explored in relation to the high-Curie Temperature Co2FeSi and Fe2CoSi compounds via generation of equilibrium ternary isothermal phase diagrams at 1160 C and 800 C to enable greater control of the microstructure for future thermomechanically processed bulk smart device fabrication.
Ph.D. in Materials Science and Engineering
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Creator: Hassan, Ahmed Ali
Date: 2017, 2017-05
Description: Bio-polymeric materials derived from renewable biomass have successfully replaced conventional materials in many applications. Despite...
Show moreBio-polymeric materials derived from renewable biomass have successfully replaced conventional materials in many applications. Despite covering 10-15% of the current global plastic market, the application of the Bio-polymeric materials in the field of building facades has hitherto been limited. Unlike the conventional façade materials, Bio-polymeric materials can lessen the carbon footprint of the building façade significantly, reduce a considerable percentage of heat loss, and contribute in alleviating the amount of C&D waste dumped in landfills each year. This will help in saving the natural resources, conserving landfill spaces, decreasing pollution rates, and reducing the overall building weight and energy consumption. Accordingly, this research aims at developing a revolutionary lightweight building façade panel, made from Bio-polymeric agri-based materials, to replace the curtain wall glass and aluminum panel in office buildings, and to assess its impact on the environment, the building energy consumption, thermal performance and structural stability. To achieve that, the research discusses in the first place the potentiality of employing these materials while exploring the main physical and environmental challenges they may confront when introduced to the building facades realm. Secondly, the research adopts rigorous selection criteria to facilitate proposing innovative opaque/transparent materials capable of handling all the environmental, thermal, optical, functional, and economic considerations of the building facade. Thus, 1236 state-of-the-art Bio-polymeric materials have been exposed to a strict methodical screening process through structured quantifiable constraints. MCDM methods have then been employed to enable sorting and ranking the resulted set of candidates considering their order-of-preference in achieving the aforementioned performance criteria. Finally, computational simulation tests have been carried out to ensure that the BioEnclos© Façade Panel satisfies all the energy and building code requirements in terms of heat transfer, energy performance, optical properties, and structural behavior. Consequently, the simulation findings have demonstrated the great capabilities the BioEnclos© Façade Panel can provide to the future of the building façades. Through its several options, the BioEnclos© Façade Panel can reduce the weight of the entire building façade by a range of 43-53%. It also can improve the façade’s thermal resistance and energy savings by a range of 31-52%. In addition, it can maximize the visible light transmittance through the façade’s assembly by a range of 15-31%. Moreover, the BioEnclos© Façade Panel can be commissioned in different colors/textures with good UV radiation resistance, self-extinguishing abilities, exceptional 50-70% reduction in CO2 emissions, and multiple end-of-life options.
Ph.D. in Architecture, May 2017
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Title: INTERACTIONS BETWEEN NANOFLUIDS AND A SOLID SUBSTRATE: ROLE OF pH AND NANOFLUID PARTICLE CONCENTRATION ON THE THREE-PHASE CONTACT ANGLE
Creator: Horiuchi, Hiroki
Date: 2013, 2013-12
Description: We investigate the effect of pH on the interactions between a silica slurry and a silica wafer substrate (TEOS) made by the chemical vapor...
Show moreWe investigate the effect of pH on the interactions between a silica slurry and a silica wafer substrate (TEOS) made by the chemical vapor deposition of tetraethylorthosilicate gas in order to understand the optimization of the Chemical Mechanical Polishing (CMP) process and develop a high-performance silica slurry. The nature of the interactions is probed by the solid-liquid interfacial energy and the electrostatic surface potential at the solid surface. An overview of the CMP process is discussed in Chapter 1. Conventional techniques used to measure the electrostatic potential at the solid/liquid interface, such as the streaming potential and potentiometric titration method, are reviewed. Although there are many techniques for measuring the surface potential of powders, such as potentiometric titration and zeta potential measurement, there is no well-established technique for measuring the surface potential of the silica wafer. Therefore, in this research, we developed a methodology to determine the surface potential and surface charge density of a silica wafer substrate in contact with a slurry. We developed a novel method for calculating the surface potential and surface charge density using the experimental data of the three-phase contact angle in conjunction with the Young- Lippmann and the Poisson-Boltzmann equations. The surface chemistry of silica is discussed in Chapter 2 to elucidate the origin of the surface charge due to the ionization of the silanol groups on a silica wafer. Since the silica wafer is always in contact with the aqueous solution during the CMP process, we specifically focus on the behavior of silica in aqueous solutions. xvi In Chapters 3 and 4, the three-phase contact angle (TPCA) on silica is measured as a function of the pH by the goniometric technique. The surface potential and surface charge density at the silica/water surface are calculated by a model based on the Young- Lippmann equation in conjunction with the Gouy-Chapman model for the electric double layer. In measurements of the TPCA on silica, two distinct regions are identified with a boundary at pH 9.5—showing a dominance of the surface ionization of silanol groups below pH 9.5 and a dominance of the dissolution of silica into the aqueous solution above pH 9.5. Since the surface chemistry changes above pH 9.5, the model is applied to solutions below pH 9.5 (ionization dominant) for the calculation of the surface potential and surface charge density at the silica/aqueous interface. In order to evaluate the model, a galvanic mica cell was made of a mica sheet and the surface potential was measured directly at the mica/water interface. The model results are validated by the experimental data from the literature, as well as the results obtained by the potentiometric titration method and the electro-kinetic measurements. The interactions between the nanofluid and solid surface are explored in Chapter 5. Measurements of three-phase contact angle of the nanofluid on a silica substrate show that the contact angle decreases as the volume fraction increases due to the formation of particle layers on the solid surface. We conclude that it is driven by the depletion attractions between the nanoparticles and a solid surface. In the calculations, the energy (based on Young’s equation) and the structural energy of silica particles (based on statistical mechanics---Henderson’s equation) are in good agreement, indicating that the formation of the nanoparticle layering occurs near the solid surface, as expected. We reference the measurement of the forces between two mica surfaces by Israelachvili and xvii Pashley (1983 and 1984) to calculate the interaction energy against the distance between the two surfaces; we found that the strong repulsive force (hydration force) at a short distance (less than 2 nm) gives rise to enough energy to change the three-phase contact angle. In addition, the calculated inter-particle energy due to the hydration force (by using a statistical mechanics approach, see Trokhymchuck et al. 2001) shows that the hydration force can dramatically increase the inter-particle energy in the case of a volume fraction of water that is from 40 to 45%. The inter-particle energy corresponds to the energy change of 3-5⁰ in the three-phase contact angle, which is same as that found in our experimental data obtained from the contact angle measurements. Finally, we conclude that the hydration force between the silica particles on the solid surface plays an important role in altering the interfacial energy between a solid and liquid.
PH.D in Chemical Engineering, December 2013
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Title: A FORGOTTEN FOUNDATION OF THE BAUHAUS: PSYCHO-PHYSIOLOGICAL AESTHETICS AND THE INCEPTION OF MODERN DESIGN THEORY
Creator: Kalkatechi, Mina
Date: 2016, 2016-12
Description: This dissertation investigates the Bauhaus during its activity in Weimar and Dessau, as a pedagogical paradigm of modern era that drew upon...
Show moreThis dissertation investigates the Bauhaus during its activity in Weimar and Dessau, as a pedagogical paradigm of modern era that drew upon different aesthetic ideas of its past, which were set in motion by a vigorous interaction with human sciences during the era of 1890-1914. As a much-contested account of modernism, the story of the Bauhaus has been rewritten in many ways. While the dominant narrative considered the school as a forceful, autonomous entity that stood triumphant in its supposed denial of history and an innovation in modern pedagogy, studies that challenge this autonomy have been exclusive to social and political precedents of the Wilhelmine era. Yet, there remains a significant need in scholarship to fully grasp the scope of the Bauhaus as an aesthetic paradigm that goes beyond an elusive devotion to modern aesthetic ideals. My inquiry aims to position the Bauhaus as an outcome of a broader epistemological framework of its immediate past. Primarily set to address the aesthetics of everyday objects, scientific endeavors in psychology and psychophysiology during this time initiated a new aesthetics, whose main aim I argue, was to render a more humanistic prospect for modern art and architecture. This different connotation of modernity was decisive to counteract the extreme skepticism and negative mentality towards technological progress that was devoid of emotion and affect. Through discussing four discursive themes, I concoct a trajectory of different artistic attempts during 1890-1914 that act as precedents to those of the Bauhaus in 1920s. By so doing, this study highlights a significant contribution to inception of modern design at the Bauhaus: the interaction of human sciences with aesthetics at the turn of the century. This new aesthetics sought to understand its perceptual borders and created a theory of affect that engaged the Bauhaus more than it has been acknowledged in the scholarship. Although this new theory pervaded artistic realms through its interaction with social aspects of design, theories of craft and industry, and modern abstraction, it still remains a forgotten contribution to the Bauhaus. As such, the era of 1890-1914 shaped modern architectural theory more vigorously than previously realized.
Ph.D. in Architecture, December 2016
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Title: THE DESIGN AND ANALYSIS OF A MULTI-PERFORMANCE 3D PRINTED CONSTRUCTION UNIT: AN ALGORITHM TO UPGRADE THE STRUCTURAL, ENVIRONMENTAL AND ASSEMBLY PERFORMANCE IN MASONRY UNITS CONSTRUCTION
Creator: Kalkatechi, Maryam
Date: 2016, 2016-12
Description: This dissertation investigates the design and prototyping process of a new masonry unit. Drawing on the advantages offered by 3D printing...
Show moreThis dissertation investigates the design and prototyping process of a new masonry unit. Drawing on the advantages offered by 3D printing industry, it seeks to improve the unit’s structural efficiency and at the same time experiment with the potential benefits of ABS plastic for its realization. The first step of this process was to formulate a parametric algorithm based on a construction unit that provided different data-sketches. Through a case-by-case analysis, the research process either used these data-sketches as the preliminary step of analysis, or used trial and error to experiment first-hand with 3D printing processes to delineate the scope of their implementation and to account for the design consequences that production techniques brought upon the final product. By such examinations, the aim is to propose a new structural system that forms a new tectonic language and offers constructability solutions for a new wall system. As the most inexpensive and available plastic, using ABS plastic for 3D printed masonry units is a promising endeavor, which all the more necessitates addressing its design challenges. To do so, this research conceived of a 3D printed unit as an arrangement of cells that combined different considerations such as handling the unit, its structural performance and modularity in a uniform, ergonomic and sustainable wall system. The key features of this assembly comprised of a waffle plate that attached the EPS panel to the slab, a sprayed EPS, the ABS plastic unit that had ties as a design element for EPS installation, an interlocking snap-fit joint that vertically fastened the units together, and a custom-designed dovetail joint for horizontal connections. The parametric algorithm modified and redefined individual cells in the corners to realize these connections. The final step of this process entailed a comprehensive comparison of the proposed wall system to alternative wall systems, namely a solid wall system, an ICF wall system, and a cavity wall system for thickness, weight and thermal performance. Using Rescheck software, I compared these wall systems to a base model set in Chicago. Ultimately, this research is a detailed elaboration of a problem-solving process that exploits the capabilities of parametric design beyond its common emphasis on creating new geometries, by means of which the proposed system offers practical solutions to the prevalent challenges in masonry unit construction.
Ph.D. in Architecture, December 2016
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Title: EFFICIENT ALGORITHMS FOR POWER ASSIGNMENT PROBLEMS
Creator: Qiao, Kan
Date: 2015, 2015-05
Description: Power assignment problems take as input a directed simple graph G = (V;E) and a cost function c : E ! R+. A solution to this problem assigns...
Show morePower assignment problems take as input a directed simple graph G = (V;E) and a cost function c : E ! R+. A solution to this problem assigns every vertex a nonnegative power, p(v). We use H = (V;B(p)) to denote the spanning subgraph of G created by this power assignment. Let B(p) denote the set of all the links established between pairs of nodes in V under the power assignment p. The minimization problem then is to find the minimum power assignment, Pp(v), subject to H satisfying a specific property. 4 variants of this problem are discussed in this paper (a) Min-Power Strong Connectivity: H = (V;B(p)) is strongly connected. (b) Min-Power Broadcast: H = (V;B(p)) has a path from the fixed source z to every other vertex. (c) Min-Power Connectivity with 2-level power (Symmetric): c : E ! f0; 1g and H = (V;B(p)) is connected. (d) Min- Power Strong Connectivity with 2-level power (Asymmetric): c : E ! f0; 1g and H = (V;B(p)) is strongly connected. We give the exact solution using an improved integer linear program for problem (a) and (b) (We do not have a section for the integer linear program of Min-Power Broadcast problem since it is very similar to Min-Power Strong connectivity). Then we try to speedup current best approximation algorithms while preserving their approximation ratio. For problem (a), we give a fast variant of 1:85-approximation algorithm with running time O(n2 log2 n). For problem (b), we give a fast variant of 2(1 + ln n)-approximation algorithm for the most general cost model with running time O(n3) and a fast variant of 4:2- approximation algorithm for 2-dimensional cost model with running time O(nm), where n = jV j and m = jEj. For both problem (c) and (d), We give 5 3-approximation algorithms that run in O(m (n)), where (n) is the inverse Ackermann function.
Ph.D. in Computer Science, May 2015
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