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Title: Investigation in the Uncertainty of Chassis Dynamometer Testing for the Energy Characterization of Conventional, Electric and Automated Vehicles
Creator: Di Russo, Miriam
Date: 2023
Description: For conventional and electric vehicles tested in a standard chassis dynamometer environment precise regulations on the evaluation of their...
Show moreFor conventional and electric vehicles tested in a standard chassis dynamometer environment precise regulations on the evaluation of their energy performance exist. However, the regulations do not include requirements on the confidence value to associate with the results. As vehicles become more and more efficient to meet the stricter regulations mandates on emissions, fuel and energy consumption, traditional testing methods may become insufficient to validate these improvements, and may need revision. Without information about the accuracy associated with the results of those procedures however, adjustments and improvements are not possible, since no frame of reference exists. For connected and automated vehicles, there are no standard testing procedures, and researchers are still in the process of determining if current evaluation methods can be extended to test intelligent technologies and which metrics best represent their performance. For these vehicles is even more important to determine the uncertainty associated with these experimental methods and how they propagate to the final results. The work presented in this dissertation focuses on the development of a systematic framework for the evaluation of the uncertainty associated with the energy performance of conventional, electric and automated vehicles. The framework is based on a known statistical method, to determine the uncertainty associated with the different stages and processes involved in the experimental testing, and to evaluate how the accuracy of each parameter involved impacts the final results. The results demonstrate that the framework can be successfully applied to existing testing methods and provides a trustworthy value of accuracy to associate with the energy performance results, and can be easily extended to connected-automated vehicle testing to evaluate how novel experimental methods impact the accuracy and the confidence of the outputs. The framework can be easily be implemented into an existing laboratory environment to incorporate the uncertainty evaluation among the current results analyzed at the end of each test, and provide a reference for researchers to evaluate the actual benefits of new algorithms and optimization methods and understand margins for improvements, and by regulators to assess which parameters to enforce to ensure compliance and ensure projected benefits.
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Title: CHARACTERIZATION OF COAGULATION AND MUSCLE ATTACHMENT MUTATIONS IN DROSOPHILA MELANOGASTER LARVAE AND THE GENERATION OF A NOVEL TRANSGLUTAMINASE LOSS OF FUNCTION MUTANT LINE
Creator: Schubert, Nina H
Date: 2014, 2014-05
Description: It is known that the protein Fondue (Fon) is involved in clotting in Drosophila melanogaster. Consequently, Fon was being studied to...
Show moreIt is known that the protein Fondue (Fon) is involved in clotting in Drosophila melanogaster. Consequently, Fon was being studied to characterize its role in the clot. During this study, it was found that Fon and the protein Tiggerin have the same expression pattern. Additionally, mutants for both proteins develop into long, thin pupae (as compared to wild type). Due to this similarity in mutant phenotype and protein localization in combination with literature citing Tiggerin to be involved in both the clot and muscle attachment, Fon was looked at for a muscle attachment phenotype. Furthermore, whilst we do know that Tiggerin is involved in the clot as well as muscle attachment, its specific role in coagulation and its muscle attachment phenotype have not been previously characterized. Due to the pleotropic role of Fon and Tiggerin in muscle attachment and clotting, the long, thin pupal phenotype was used as an indicator of potential clotting mutants in a search at the Bloomington stock center. There, 722 lines were found to have long, thin pupae and from these the 9 lines with the strongest mutant phenotypes were selected to test for coagulation and/or muscle attachment abnormalities. Our collaborator took confocal micrographs of third instar larval fillets obtained from these lines as a means of visualizing actin structure within the muscles. From these images, it was found that the Cchl mutant line had the most severely detached muscles and, consequently, this line was selected as the best candidate for a clotting and muscle attachment mutation and was subjected to further study. The role of a third protein, transglutaminase (TG), which is also involved in clotting, has not been fully characterized due to the lack of a null line. To address this deficiency and fully characterize the role of TG in coagulation in Drosophila, a line with an inactivated TG gene was used as a starting line to generate a null line.
M.S. in Biology, May 2014
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Title: HIGH GAIN HIGH EFFICIENCY RESONANT DC-DC CONVERTER
Creator: Shang, Fei
Date: 2016, 2016-12
Description: Low voltage power sources such as batteries, solar panels, and fuel cells have played an important role in applications such as automotive...
Show moreLow voltage power sources such as batteries, solar panels, and fuel cells have played an important role in applications such as automotive system, renewable energy power generation and so on. These applications of the low voltage power sources require a high gain DC-DC step-up converter. Research in this area shows great improvements for the converter topologies. As the power requirements keep increasing, the converter is going to sustain a very high input current. This high current can bring many design challenges in the existing topologies, such as high component current stress and power loss, complex and costly design for magnetic components, high input current ripple, etc. To address these challenges, a new topology of high gain DCDC step-up converter is needed. Evaluation of current high gain DC-DC converter topologies introduces the idea of the new topology which combines the advantages of different topologies and techniques. The new topology of high gain DC-DC converter suitable for low-voltage-high-current application is proposed in this dissertation. It consists of interleaved step-up topology, resonant circuit, and high frequency transformer. The topology has many merits such as high gain capability, high efficiency, low components stress and requirement of the transformer, simple topology with less number of active switching device, and easy to control. The dissertation carries out theoretical analysis of the proposed topology under different operating modes and the voltage gain has been deduced for each mode. The high voltage gain capability comes from 3 parts, which are interleaved step-up function, transformer turns-ratio and output voltage doubler circuit. Some variants of the topology make it more practical in many applications. In order to realize the design of the proposed converter, the design guidelines of major circuit components have been well studied in this dissertation. The switching power devices current stress and power loss are discussed in detailed to show the trend of their variation under different operating modes. The selection of transformer turns-ratio with the consideration of its impact to the component stress and power loss has been fully analyzed. The design method of the resonant tank is also well studied based on the resonant component value selection and its influence to the other components. Input inductor design is related to the current ripple requirement and this relationship is discussed thoroughly. These guidelines can be used to support the practical design of the proposed converter for different specifications. An effective output voltage regulation of the converter is essential for the proposed converter. To design a proper controller of the converter, the system transfer function is needed. The methods of system dynamic modeling have been fully studied in this dissertation. System dynamic state-space models are acquired by using generalized averaging method and the results validate the effectiveness of the method. Small signal model of the converter is achieved by linearization of the dynamic model around the operating points and system transfer functions are available at di↵erent operating points. The stability study indicates that the system is stable at all operating points, though there are several transfer functions at some operating points containing RHP zeros which can cause system unstable if the closed-loop controller is poorly designed. The parameter sensitivity study shows that the system transfer function is not greatly affected by the variation of the leakage inductance and load resistance. A design of PI controller is introduced in the dissertation and closed loop control of the converter is implemented to achieve the output voltage regulation. Simulations in PSIM and MATLAB Simulink have been carried out to validate the circuit operation and support the design analysis. A 2kW prototype has been built for experimental testing. The experimental results are in a good agreement with the theoretical analysis and efficiency of over 95% has been achieved for the nominal operating point.
Ph.D. in Electrical Engineering, December 2016
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Title: FACTORS AFFECTING ACCEPTANCE OF DISABILITY: A PILOT STUDY AMONG CHINESE INDIVIDUALS WITH SPINAL CORD INJURY
Creator: Jiao, Jie
Date: 2012-07-07, 2012-07
Description: In the rehabilitation literature, acceptance of disability has been identified as one of the best indicators of positive adjustment following...
Show moreIn the rehabilitation literature, acceptance of disability has been identified as one of the best indicators of positive adjustment following an acquired disability (Elliott, Uswatte, Lewis, & Palmatier, 2000) and has significant implications in vocational rehabilitation and overall community integration (Green, Pratt, & Grigsby, 1984; Melamed, Groswasser, & Stern, 1992; Snead, & Davis, 2002). However, existing literature on acceptance of disability is primarily based on Western samples. The current study focused on people with spinal cord injuries and was the first attempt to apply the construct of acceptance of disability to a mainland Chinese sample. It also examined if demographic variables (i.e., age, gender, education level), disability related variables (i.e., functional limitations, pain), and psychosocial variables (i.e., depression, selfesteem, perceived social support, self-efficacy) are significantly related to AD. Hierarchical Regression revealed that higher self-esteem and less depressive symptoms were significantly associated with better acceptance of disability. The current study also indicated an alarmingly high prevalence of depression among Chinese individuals with spinal cord injury and suggested a mediating effect of depression and self-esteem on social support.
Ph.D. in Psychology, July 2012
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Title: LEARNING THE STRUCTURE OF PROBABILITY NETWORKS WITH DATA UNCERTAINTY
Creator: Zhang, Sisi
Date: 2014, 2014-07
Description: This paper studies how data uncertainties impact structure learning. Learning the structure of a probabilistic network from observational data...
Show moreThis paper studies how data uncertainties impact structure learning. Learning the structure of a probabilistic network from observational data has been traditionally studied assuming that there are no uncertainties in the data. This paper focuses on the uncertainties that result in “misclassification errors” in the contingency tables based on which the independence tests are carried out. The impact of misclassification errors is investigated through a sensitivity study which focuses on identifying the boundaries of misclassification errors within which the learned structure from erroneous data is identical to the true structure. Mathematical derivations for obtaining this boundary are presented. The analytical results are showed by a case study in epidemiology.
M.S. in Applied Mathematics, July 2014
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Title: SPECTRUM SHARING OPPORTUNITY FOR LTE AND AIRCRAFT RADAR IN THE 4.2 - 4.4 GHZ BAND
Creator: Singh, Rohit
Date: 2017, 2017-07
Description: The Federal Communications Commission (FCC) states that America is facing a spectrum crunch and there is no easy way to meet this increasing...
Show moreThe Federal Communications Commission (FCC) states that America is facing a spectrum crunch and there is no easy way to meet this increasing demand, hence spectrum sensing and sharing has gotten significant attention in the Spectrum Com- munity. Spectrum is an increasingly scarce natural resource which needs to be used to the fullest. Using modern techniques, spectrum bands can be reused such that they do not interfere with the current users in a band. There are many bands in the RF Spectrum which are underutilized and can be reused in the space-time domain. A number of bands have been recognized as candidates for spectrum sharing. In this dissertation, we consider the 4.2 − 4.4GHz band which is dedicated for used by the radar altimeter fixed on aircraft to measure their elevation above the earth’s surface. This spectrum is currently underutilized and with care can be shared with other technologies. This thesis examines the current use of this spectrum as a func- tion of time and location and presents a methodology for assessing whether harmful interference is experienced by either the incumbent radar usage or by a proposed wireless secondary broadband user. However, this band is a potential “safety of life” spectrum which is used by aircraft during landing and takeoff. Improper sharing of this band could cause interference at the radar, which would result in false attitude detection by the radar. Because of its advance technology, LTE should can be a good sharing candidate for this sensitive band. We propose sharing of this band with small cells (perhaps inside buildings) in urban and/or suburban areas, where there is a high demand for LTE and the attenuation from the environment is high enough to cause less interference at the radar altimeters. In this thesis, we propose to detect the aircraft (i.e. the altimeter radars) us- ing the Automatic Dependent Surveillance Broadcast (ADS-B) data which is broad- casted by an aircraft. This aircraft detection mechanism helps us to take intelligent sharing approaches with LTE using the space-time domain. Since the performance of the radar altimeter is safety-of-life critical, a deep understanding of co-existence between these systems is necessary to evaluate whether sharing is feasible. Given the availability of historical ADS-B data, what we believe is an appropriate analysis of Chicagoland has been done to propose implementation of a mix of Exclusion and Coordination zones in this area in the space-time domain. The novelty of this work is to develop spectrum sharing opportunities with radars which are highly transient and their locations are unpredictable due to emergency or traffic or weather. This thesis presents a method for evaluation of the potential for spectrum sharing between the ground-based LTE systems and commercial radar altimeters.
M.S. in Computer Science, July 2017
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Title: MULTIPLE-INPUT MULTIPLE-OUTPUT NONLINEAR CONTROL OF SELECTIVE CATALYTIC REDUCTION SYSTEMS
Creator: Dong, Siwei
Date: 2015, 2015-05
Description: Selective catalytic reduction (SCR) is one of the most promising solutions to meet the future nitrogen oxides (NOx) emissions regulations for...
Show moreSelective catalytic reduction (SCR) is one of the most promising solutions to meet the future nitrogen oxides (NOx) emissions regulations for heavy-duty diesel vehicles. However, such vehicles often operate in highly transient operations in which mobile selective catalytic reduction systems encounter significant efficiency challenges, especially when the engine is under a low load. A detailed simulation model of the SCR system was developed in the Gamma Technologies simulation suite and a baseline model of feedback control on SCR was constructed. Experiment data for the exhaust gas composition and conditions from a Cummins ISB engine was used to provide the input parameters for the SCR model. The results reveal that in the low-load conditions, the efficiency of NOx reduction in the SCR system is very low, and the level NOx concentration exiting the vehicle could be over 5 times than the limitation set by the US Environmental Protection Agency (EPA). However, these issues are encountered in part due to the fact that current SCR controls focus solely on the aftertreatment components and treat the incoming engine output conditions as system disturbances. To address the low NOx conversion problems encountered in low load conditions, a new integrated engine and aftertreatment control model was designed. This integrated approach improves the SCR system efficiency by using available feedback and modulating the upstream air/fuel ratio to provide more favorable SCR inlet conditions. From experiment data analysis, the engine’s air/fuel ratio is shown to have a critical impact on exhaust gas temperature and exhaust oxygen fraction, which highly affect the SCR reactions. In order to integrate the engine and aftertreatment system, a model of the SCR dynamics was created and validated and a simple model of the relationship between the engine’s air/fuel ratio and resulting exhaust temperature and composition is leveraged. The new model-based control strategy is proven to be effective to improve SCR system performance at low-load operations. With a small value shift in air/fuel ratio, the efficiency of low-load SCR system can increase from 40% to 85% at low load operating conditions.
M.S. in Mechanical and Aerospace Engineering, May 2015
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Title: SUBSTATION PLANNING FOR RURAL DISTRIBUTION SYSTEMS IN AFRICAN COUNTRIES
Creator: Soyoye, Oluwadamilola
Date: 2016, 2016-12
Description: In sub-Saharan Africa, only 35% of the population is connected to grid electricity [2]. Grid-connected parts face serious transmission and...
Show moreIn sub-Saharan Africa, only 35% of the population is connected to grid electricity [2]. Grid-connected parts face serious transmission and distribution challenges. There is also the challenge of electricity demand being greater than electricity supply. These issues in all levels of the traditional power system – generation, transmission and distribution have led to gross inadequacy of electricity supply. This research focuses on the capital intensive Power Distribution Planning (PDP). Most problems in the distribution system affect the consumer directly. Distribution substation planning, a critical part of the PDP, particularly addresses the issue of overloaded distribution systems. It is not uncommon for substation transformers in some African communities to become damaged because of overloading. The choice of location, sizing, siting and number of substations is determined by considering load distribution, feeder lengths and sizes, and the interruption costs. The research illustrates a framework for substation planning, incorporating possible future load growths over a particular period to forestall unwanted failures in the distribution system. A direct algorithm is used, where the substation capacity is computed manually from the load levels at different points. This algorithm is later combined with the Mixed Integer Linear Programming (MILP) approach solved with the CPLEX solver in MATLAB.
M.S. in Electrical Engineering, December 2016
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Title: STATISTICAL METHODS FOR LARGE-SCALE TRANSPORTATION NETWORK TRAFFIC VOLUME FORECASTING
Creator: Meng, Xiao
Date: 2012-11-27, 2012-12
Description: Forecasting is the procedure of making declarations about future events whose actual outcomes have not yet been observed. A lot of decisions...
Show moreForecasting is the procedure of making declarations about future events whose actual outcomes have not yet been observed. A lot of decisions are made based on predictions of future unknown events. Knowing the essence of forecasting, it is not hard to interpret what traffic volume forecasting is. Traffic volume forecasting is the process of estimating the number of vehicles that will be on a planned highway in the future. It plays important roles in different aspects of transportation and related field, such as highway level of service analysis, measure of effectiveness, highway improvement and expansion, geometric design and air quality analysis, etc. A good forecast is needed for decision making in future land use and transportation planning. City and county planners can provide useful information about land use planning and projected developments. County engineers may provide information about future county projects that may cause detours and changes in traffic patterns along a trunk highway. Highway designers need forecasted traffic volumes to ensure proper geometric designs. Since short term forecasting has been a hot topic on research, many statistical methods have been used, such as the mean, historical moving average, exponential smoothing, and autoregressive integrated moving average. Among them, Box Jenkins method (Autoregressive Integrated Moving Average) has been found as the best model on forecasting of time series data with seasonality and trend.
M.S. in Civil Engineering, December 2012
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Title: COLLABORATIVE CONSUMPTION: PROFITS, CONSUMER BENEFITS, AND ENVIRONMENTAL IMPACTS
Creator: Supangkat, Hendrarto Kurniawan
Date: 2014, 2014-05
Description: With increasingly connected consumers and technological advancement, peer- to-peer sharing is emerging as a consumer-led initiative, which is...
Show moreWith increasingly connected consumers and technological advancement, peer- to-peer sharing is emerging as a consumer-led initiative, which is aimed to exploit slack capacities and lower the cost of consuming private goods. Sharing is praised for its potential bene ts of improving consumer access, consumer surplus, and environmental impact. On the other hand, sharing may possess credible threats to producers because of cannibalization and reduced sales quantity. This thesis is composed of three papers on the subject of peer-to-peer sharing of durable goods, e.g., cars, bikes, gadgets, and household appliances. The rst paper studies pricing and product design decisions of a single-product monopolist in a market. We identify the conditions under which a rm would accom- modate or hinder peer-to-peer sharing by pricing the product appropriately. We nd that the rm's pro t can be enhanced only when the consumer valuation heterogene- ity is neither too high nor too low, and the product's intrinsic value is su ciently high. In addition, contrary to the conventional wisdom, we show that sharing does not always improve consumer access to products. Furthermore, some consumers may end up being worse o . Finally, we nd that social sharing may enhance or impede product innovation, depending on consumer heterogeneity and the size of sharing groups. In the second paper, we study whether social sharing will encourage or discour- age product di erentiation. We nd that the two ways of expanding the market, one consumer-initiated and one rm-initiated, can be strategic complements or substi- tutes, depending on consumer heterogeneity, group size, product intrinsic value, and cost structure. We characterize such conditions. For example, we show that accom- modating sharing provides the rm a higher incentive to introduce a di erentiated product when the product intrinsic value and consumer heterogeneity are both low, x or are both high. We also extend the study by allowing consumers to endogenously choose their sharing group size, and show that it may enhance or worsen the rm's pro t. The third paper focuses on the environmental impact stemming from produc- tion and consumption, in the presence of peer-to-peer sharing. The product usage of sharing consumers is modeled as a function of capacity congestion and group size. We show that a "danger" zone exists where sharing is pro table for the rm but is not friendly to the environment. When the rm has an in uence on the sharing group size (e.g., by promoting sharing programs in metropolitan areas or college towns), the economic incentive and environmental impact can be aligned. Speci cally, we nd that stronger congestion e ects may induce the producer to promote sharing in larger groups, which in turn results in a more positive environmental impact. Such situations are more likely to occur when the product unit cost is large. Moreover, we characterize conditions under which the rm may prefer heterogeneous networks composed of groups with di erent sizes or social networks with lower homophily, and meanwhile the environmental impact can be improved.
PH.D in Management Science, May 2014
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Title: NUMERICAL SIMULATIONS OF CURVATURE WEAKENING MODEL OF REACTIVE HELE-SHAW FLOW
Creator: Zhao, Meng
Date: 2013, 2013-12
Description: In this paper, we study a moving interface problem in a Hele-Shaw cell, where two immiscible reactive fluids meet at the interface and...
Show moreIn this paper, we study a moving interface problem in a Hele-Shaw cell, where two immiscible reactive fluids meet at the interface and initiate chemical reactions. A new gel-like phase is produced at the interface and may modify the elastic bending property there. We model the interface as an elastic membrane with a local curva- ture dependent bending rigidity. In the first part of this paper, we review the linear stability analysis on a curvature weakening model, and derive critical flux conditions such that a Hele-Shaw bubble can develop unstable fingering pattern and self-similar morphology. In the second part of this report, we develop a boundary integral nu- merical algorithm to perform nonlinear simulations. Preliminary numerical results show that in the nonlinear regime, there also exist stable self-similar solutions.
M.S. in Applied Mathematics, December 2013
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Title: TWO-LAYERED DEPTH ESTIMATION USING SEMI-GLOBAL MATCHING WITH MUTUAL INFORMATION
Creator: Zhang, Chen
Date: 2014, 2014-07
Description: Depth estimation plays an important role in three-dimensional computer vision area. Its recent development focuses on real-time application....
Show moreDepth estimation plays an important role in three-dimensional computer vision area. Its recent development focuses on real-time application. To be able to provide depth map for real-time applications like pedestrian detection and intelligent vehicles, three challenges must be overcome: 1. Real-time processing speed; 2. Insensitive to brightness change; 3. Clear boundaries and smooth surface. The thesis first describes the major steps of depth estimation, then many commonly used methods are reviewed. From them and other related real-time method, we found that the iteration based semi-global matching with mutual information has much potential to be improved. Based on that, the thesis proposed a method with two layers to provide depth map for pedestrian detection. The low resolution layer’s task is to produce a coarse depth map as quick as possible, then it helps to produce accurate mutual information distribution without iterations. The Full-resolution layer applies semi-global matching with two optional simplification schemes to speed up. The proposed method is implemented on both CPU and GPU. Experimental results and evaluation shows that it has great insensitivity to brightness changes and achieves real-time processing speed while maintaining a comparable performance with state-of-the-art real-time depth estimation methods.
M.S. in Electrical Engineering, May 2014
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Title: ACTION RECOGNITION USING SPATIO-TEMPORAL FEATURE EXTRACTION
Creator: Mesmakhosroshahi, Maral
Date: 2012-04-24, 2012-05
Description: The importance of automatically recognition of human activities and it's ap- plications increase as the technology is growing fast these days....
Show moreThe importance of automatically recognition of human activities and it's ap- plications increase as the technology is growing fast these days. In this thesis we focus on the action recognition techniques using 3D feature extraction techniques and try to improve the performance of the available feature extraction methods to have more accurate action classi cation. This thesis is based on spatio-temporal feature extraction techniques that can be extension of two dimensional feature extractions. At rst, 3D corner detector and 3D blob detector, two popular interest point detectors that successfully extended to spatio-temporal domain are reviewed. 3D corner detector is an extension of Harris corner detector which is proposed for corner detection in space-time and 3D blob detector is the 3D version of Hessian blob detector. A method is proposed to improve the robustness of 3D corner detectors against illumination variances based on the application of sigmoid function in contrast stretching. These interest points need to be described by feature vectors. In this part also a review on the SIFT descriptor and it's 3D extension is done. Another 3D feature descriptor discussed in this thesis is Cuboid. In the feature description part a new method is proposed based on the 3D SIFT feature descriptor by changing the binning method of the gradient orientation histogram to a non-uniform binning scheme. Using these non-uniform bins increases the accuracy of action classi cation by focusing on the areas near the interest points. Action classi cation is done using bag of features and supervised learning techniques. For making a dictionary of features, feature vectors are clustered by K-means clustering method and support vector machine is used for classi cation of human activities.
M.S. in Electrical Engineering, May 2012
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Title: COVERAGE AND CONNECTIVITY IN WIRELESS NETWORKS
Creator: Xu, Xiaohua
Date: 2012-04-25, 2012-05
Description: The limited energy resources, instability, and lacking central control in wireless networks motivates the study of connected dominating set ...
Show moreThe limited energy resources, instability, and lacking central control in wireless networks motivates the study of connected dominating set (CDS) which serves as rout- ing backbone to support service discovery, and area monitoring and also broadcasting. The construction of CDS involves both coverage and connectivity. We ¯rst study sev- eral problems related to coverage. Given are a set of nodes and targets in a plane, the problem Minimum Wireless Cover (MWC) seeks the fewest nodes to cover the targets. If all nodes are associated with some positive prices, the problem Cheapest Wireless Cover (CWC) seeks a cheapest set of nodes to cover the targets. If all nodes have bounded lives, the problem Max-Life Wireless Cover (MLWC) seeks wireless coverage schedule of maximum life subject to the life constraints of individ- ual nodes. We present a polynomial time approximation scheme (PTAS) for MWC, and two randomized approximation algorithms for CWC and MLWC respectively. Given a node-weighted graph, the problem Minimum-Weighted Dominating Set (MWDS) is to ¯nd a minimum-weighted vertex subset such that, for any vertex, it is contained in this subset or it has a neighbor contained in this set. We will propose a (4+²)-approximation algorithm for MWDS in unit disk graphs. Meanwhile, for the connecting part, given a node-weighted connected graph and a subset of terminals, the problem Node-Weighted Steiner Tree (NWST) seeks a lightest tree connecting a given set of terminals in a node-weighted graph. We present three approximation algorithms for NWST restricted to UDGs. This dissertation also explores the applications of CDS, and develops e±cient algorithms for the applications such as real-time aggregation scheduling in wireless networks. Given a set of periodic aggregation queries, each query has its own period , and the subset of source nodes Si containing the data, we ¯rst propose a family of e±cient and e®ective real-time scheduling protocols that can answer every job of each query task within a relative delay under resource constraints by addressing the following tightly coupled tasks: routing, transmission plan constructions, node activity scheduling, and packet scheduling. Based on our protocol design, we further propose schedulability test schemes to e±ciently and e®ectively test whether, for a set of queries, each query job can be ¯nished within a ¯nite delay. We also conduct extensive simulations to validate the proposed protocol and evaluate its practical performance. The simulations corroborate our theoretical analysis.
Ph.D. in Computer Science, May 2012
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Title: LOG ANALYSIS FOR RELIABILITY MANAGEMENT IN LARGE-SCALE SYSTEMS
Creator: Zheng, Ziming
Date: 2012-07-16, 2012-07
Description: With the increasing scale and complexity of high performance computing (HPC) systems, reliability management is becoming a major concern....
Show moreWith the increasing scale and complexity of high performance computing (HPC) systems, reliability management is becoming a major concern. System logs are the primary source of information to understand and analyze system problems. Nevertheless, manual log processing is time-consuming, error-prone, and not scalable. Currently little study has been done on automated log analysis for practical use in HPC systems. In this thesis, we present a log analysis infrastructure by exploiting data mining and machine learning technologies. Our work can be broadly divided into four parts: log pre-processing, online failure prediction, automatic root cause diagnosis, and reliability modeling. We evaluate our results by means of system logs collected from production HPC systems. This work can greatly improve our understanding of faults and failures arising from hardware/software components and their interactions. It can further facilitate the reliability management for HPC systems.
Ph.D. in Computer Science, July 2012
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Title: PERFORMANCE ANALYSIS AND OPTIMIZATION OF LARGE-SCALE SCIENTIFIC APPLICATIONS
Creator: Wu, Jingjin
Date: 2013, 2013-07
Description: Scientific applications are critical for solving complex problems in many areas of research, and often require a large amount of computing...
Show moreScientific applications are critical for solving complex problems in many areas of research, and often require a large amount of computing resources in terms of both runtime and memory. Massively parallel supercomputers with ever increasing computing power are being built to satisfy the need of large-scale scientific applications. With the advent of petascale era, there is an enlarged gap between the computing power of supercomputers and the parallel scalability of many applications. To take full advantage of the massive parallelism of supercomputers, it is indispensable to improve the scalability of large-scale scientific applications through performance analysis and optimization. This thesis work is motivated by cell-based AMR (Adaptive Mesh Refinement) cosmology simulations, in particular, the Adaptive Refinement Tree (ART) application. Performance analysis is performed to identify its scaling bottleneck, a performance emulator is designed for efficient evaluation of different load balancing schemes, and topology mapping strategies are explored for performance improvements. More importantly, the exploration of topology mapping mechanisms leads to a generic methodology for network and multicore aware topology mapping, and a set of efficient mapping algorithms for popular topologies. These have been implemented in a topology mapping library – TOPOMap, which can be used to support MPI topology functions.
PH.D in Computer Science, July 2013
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Title: A CONCEPTUAL SOLAR CHIMNEY PLANT AND FLORAL FARM USING ETFE AND BAMBOO
Creator: De Vita, Niels
Date: 2012-11-20, 2012-12
Description: Motivated by a desire to create an architectural response to the environmental and social challenges of today, the following thesis project...
Show moreMotivated by a desire to create an architectural response to the environmental and social challenges of today, the following thesis project attempts to offer new paths for the future development of the solar chimney energy plant concept originally developed by the German engineer Jӧrg Schlaich in the early 1980s. The starting point of this thesis was to analyze the solar chimney prototype completed in the Manzanares desert in 1982 in order to understand the parameters guiding the design. The analysis allowed me to better understand the potential of the concept and to recognize the opportunity that existed to push the technological boundaries to craft a new design that reflects the current socio-political, economical and environmental context we live in. In the following pages, I attempt to demonstrate that the concept could be made even more appealing through the use of technology and locally available resources. By doing this, I seek to reinvigorate the idea, opening paths for a new conversation about the potential of the project as a social agent for progress. Throughout this thesis, I remain respectful and aware of the accomplishments of the pioneers before me, simply taking cues from their work to suggest new alternatives and solutions to a problem that has been made even more pressing due to the world’s energy crisis and economic uncertainty.
M.S. in Architecture, December 2012
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Title: IMPROVEMENT OF BUS TRANSIT OPERATIONS BY MINIMIZING NON-REVENUE TRAVEL TIME
Creator: Arthur, Christina
Date: 2012-06-04, 2012-07
Description: There are many activities in which a transit agency can investigate reduce costs. Three main activities include service cuts, renegotiations...
Show moreThere are many activities in which a transit agency can investigate reduce costs. Three main activities include service cuts, renegotiations of union labor contracts and modifications to bus operations. The first activity, cutting service, is often a last resort because not only must an agency adhere to its budget but also its service standards. Service cutting can involve route eliminations, stop eliminations, reroutes and reductions in spans of service and frequency of service. These service cuts greatly impact the riders in which routes serve as well as the image of the agency. In order to maintain customer satisfaction and ridership, an agency may decide to employ the latter two activities. In essence these two types of activities, singularly or in combination, can produce a reduction in overhead costs to the agency by more efficiently operating services. This paper focuses on modifications to bus operations as it relates to pull-in and pull-out trips, commonly referred to as deadheading and operator travel to relief points. Using the urban bus operation of the Chicago Transit Authority, a model is developed to assign routes to garages given the locations of the pull-in and pull-out locations associated with each route. As the system currently exists, there are seven garages distributed across the city from which 144 bus routes start and end. Many of these routes are operated out of multiple garages. The main reason for these route-to-multi-garage assignments is garage capacity and scheduling needs. The goal of this research is to determine how routes can be assigned to one specific garage and still meet the requirements given by the schedule.
M.S. in Civil Engineering, July 2012
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Title: DYNAMICS OF A THREE-DIMENSIONAL FOUR-BAR LINKAGE SUBJECT TO RANDOM EXTERNAL FORCING
Creator: Lytell, Mark R.
Date: 2011-11-15, 2011-12
Description: This thesis explores the dynamics of a three-dimensional four-bar mechanical linkage subject to random external forcing. The Lagrangian...
Show moreThis thesis explores the dynamics of a three-dimensional four-bar mechanical linkage subject to random external forcing. The Lagrangian formulation of the equations of motion are index-3 stochastic di erential-algebraic equations (SDAE) that describe the time evolution of the sample paths of the generalized coordinates, velocities, and Lagrange multipliers as stochastic processes. We solve the SDAEs using two di erent approaches: inverse dynamics, Case Study 1, via independent, successive solution of the nonlinear equations for each kinematic variable, where the time evolution of one generalized coordinate is prescribed; and direct dynamics, Case Study 2, via direct solution of the SDAEs in the index-1 formulation, using fourth-order stochastic backward di erentiation formula (BDF) with modi ed Newton iteration and position and velocity stabilization (Ascher and Petzold [2]), where the (deterministic) input driving torque is prescribed. For the particular application of a three-dimensional swing gate security system, we conduct numerical experiments for both approaches. In Case Study 1, we simulate the random external forcing as a Gaussian wind speed process that applies stochastic wind drag onto the gate. The kinematic variables are deterministic, while the required input driving torque is a stochastic process. In Case Study 2, we apply the external forcing as a resistive torque with additive Gaussian noise modeling the wind drag; the kinematic variables are stochastic processes. For both cases, we apply four mean wind speeds: 0 mph (deterministic only), 10 mph, 20 mph, and 30 mph, from which we compute the deterministic solution and three stochastic sample paths for each stochastic process. The overall conclusions are that direct solution is possible for inverse dynamics, that the solution of index-1 SDAEs in multibody dynamics is tractable since the mass matrix is symmetric and positive de nite, and that the deterministic solution is the expectation of the sample paths.
M.S. in Applied Mathematics, December 2011
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Title: PHYSICS-PRESERVING FINITE DIFFERENCE SCHEMES FOR THE POISSON-NERNST-PLANCK EQUATIONS
Creator: Flavell, Allen
Date: 2014, 2014-07
Description: The Poisson-Nernst-Planck equations are a system of nonlinear di erential equations that describe ow of charged particles in solution. This...
Show moreThe Poisson-Nernst-Planck equations are a system of nonlinear di erential equations that describe ow of charged particles in solution. This dissertation is about the design of numerical schemes to solve this system which preserves global properties exhibited by the system. There are two major advances presented. The rst is the design of schemes that conserve mass globally when the system is coupled with no- ux boundary conditions. Most notably, a scheme using central di erencing and TR-BDF2 achieves second order accuracy in both space and time, while also conserving global mass is presented. The second is the design of a more general scheme that preserves the time-varying properties of the free energy of the system. One such a scheme uses central di erencing in space and trapezoidal integration in time to achieve second order accuracy in both space and time, while also preserving the energy dynamics, but at the cost of requiring positivity of the solution. There is also a discussion of solution methods: the classic Newton iteration scheme is compared with a modi ed Gummel iteration scheme for the purpose of solving the transient equations. The intended application of this work is the modeling of ion channels, and many of the simulations presented use parameters consistent with models of ion channels.
Ph.D. in Applied Mathematics, July 2014
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