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Title: AN ADAPTIVE RESCALING SCHEME FOR COMPUTING HELE-SHAW PROBLEMS
Creator: Zhao, Meng
Date: 2017, 2017-07
Description: In this thesis, we develop efficient adaptive rescaling schemes to investigate interface instabilities associated with moving interface...
Show moreIn this thesis, we develop efficient adaptive rescaling schemes to investigate interface instabilities associated with moving interface problems. The idea of rescaling is to map the current time-space onto a new time-space frame such that the interfaces evolve at a chosen speed in the new frame. We couple the rescaling idea with boundary integral method to demonstrate the efficiency of the rescaling idea, though it can be applied to Cartesian-grid based method in general. As an example, we use the Hele-Shaw problem to examine the efficiency of the rescaling scheme. First, we apply the rescaling scheme to a slowly expanding interface. In the new frame, the evolution is dramatically accelerated, while the underlying physics remains unchanged. In particular, at long times numerical results reveal that there exist nonlinear, stable, self-similarly evolving morphologies. The rescaling idea can also be used to simulate the fast shrinking interface, e.g. the Hele-Shaw problem with a time dependent gap. In this case, the rescaling scheme slows down the interface evolution in the new frame to remove the severe time step constraint that makes the long-time simulations prohibitive. Finally, we study an analytical solution to the stability of the interface of the Hele-Shaw problem, assuming a small surface tension under a time dependent flux Q(t). Following [116, 109], we find the motions of daughter singularity ζd and simple singularity ζ0 do not depend on the flux Q(t). We also find a criterion to identify the relation between ζ0 and ζd.
Ph.D. in Applied Mathematics, July 2017
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Title: WIRELESS SCHEDULING IN MULTI-CHANNEL MULTI-RADIO MULTIHOP WIRELESS NETWORKS
Creator: Wang, Zhu
Date: 2014, 2014-07
Description: Maximum multi ow (MMF) and maximum concurrent multi ow (MCMF) in multi-channel multi-radio (MC-MR) wireless networks have been well-studied in...
Show moreMaximum multi ow (MMF) and maximum concurrent multi ow (MCMF) in multi-channel multi-radio (MC-MR) wireless networks have been well-studied in the literature. They are NP-hard even in single-channel single-radio (SC-SR) wireless networks when all nodes have uniform (and xed) interference radii and the positions of all nodes are available. This disertation studies maximum multi ow (MMF) and maximum concur- rent multi ow (MCMF) in muliti-channel multi-radio multihop wireless networks under the protocol interference model in the bidirectional mode or the unidirectional mode. We introduce a ne-grained network representation of multi-channel multi- radio multihop wireless networks and present some essential topological properties of its associated con ict graph. It was proved that if the number of channels is bounded by a constant (which is typical in practical networks), both MMF and MCMF admit a polynomial-time ap- proximation scheme under the protocol interference model in the bidirectional mode or the unidirectional mode with some additional mild conditions. However, the run- ning time of these algorithms grows quickly with the number of radios per node (at least in the sixth order) and the number of channels (at least in the cubic order). Such poor scalability stems intrinsically from the exploding size of the ne-grained network representation upon which those algorithms are built. In Chapter 2 of this dissertation, we introduce a new structure, termed as concise con ict graph, on the node-level links directly. Such structure succinctly captures the essential advantage of multiple radios and multiple channels. By exploring and exploiting the rich structural properties of the concise con ict graphs, we are able to develop fast and scalable link scheduling algorithms for either minimizing the communication latency or maximizing the (concurrent) multi ow. These algorithms have running time growing linearly in both the number of radios per node and the number of channels, while not sacri cing the approximation bounds. While the algorithms we develop in Chapter 2 admit a polynomial-time ap- proximation scheme (PTAS) when the number of channels is bounded by a constant, such PTAS is quite infeasible practically. Other than the PTAS, all other known approximation algorithms, in both SC-SR wireless networks and MC-MR wireless networks, resorted to solve a polynomial-sized linear program (LP) exactly. The s- calability of their running time is fundamentally limited by the general-purposed LP solvers. In Chapter 3 of this dissertation, we rst introduce the concept of interference costs and prices of a path and explore their relations with the maximum (concurrent) multi ow. Then we develop purely combinatorial approximation algorithms which compute a sequence of least interference-cost routing paths along which the ows are routed. These algorithms are faster and simpler, and achieve nearly the same approximation bounds known in the literature. This dissertation also explores the stability analysis of two link scheduling in MC-MR wireless networks under the protocol interference model in the bidirectional mode or the unidirectional mode. Longest-queue- rst (LQF) link scheduling is a greedy link scheduling in multihop wireless networks. Its stability performance in single-channel single-radio (SC-SR) wireless networks has been well studied recently. However, its stability performance in multi-channel multi-radio (MC-MR) wireless networks is largely under-explored. We present a stability subregion with closed form of the LQF scheduling in MC-MR wireless networks, which is within a constant factor of the network stability region. We also obtain constant lower bounds on the efficiency ratio of the LQF scheduling in MC-MR wireless networks under the protocol interference model in the bidirectional mode or unidirectional mode. Static greedy link schedulings have much simpler implementation than dy- namic greedy link schedulings such as Longest-queue-frst (LQF) link scheduling. However, its stability performance in multi-channel multi-radio (MC-MR) wireless networks is largely under-explored. In this dissertation, we present a stability subre- gion with closed form of a static greedy link scheduling in MC-MR wireless networks under the protocol interference model in the bidirectional mode. By adopting some special static link orderings, the stability subregion is within a constant factor of the stable capacity region of the network. We also obtain constant lower bounds on the throughput efficiency ratios of the static greedy link schedulings in some special static link orderings.
Ph.D. in Computer Science, July 2014
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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: APPLICATION OF SPECTRUM OBSERVATORY MEASUREMENTS TO SUPPORT TRAFFIC MODEL-BASED DYNAMIC SPECTRUM ACCESS
Creator: Taher, Tanim Mohammed
Date: 2014, 2014-07
Description: In a 2012 report, the President’s Council of Advisors in Science and Technology (PCAST) published a memorandum that calls for the...
Show moreIn a 2012 report, the President’s Council of Advisors in Science and Technology (PCAST) published a memorandum that calls for the identification of 1000 MHz of Federal Spectrum to be shared with private (commercial) users. This dissertation proposes a system that employs RF measurements for spectrum usage modeling and Dynamic Spectrum Access (DSA) methodologies that utilize the modeling information to permit sharing of wireless resources. A procedure called the Comprehensive Band Modeling (CBM) procedure is developed that automatically models measured RF data from any band of interest and identifies the locations of signals and holes present in the band. The output of the CBM procedure is summarized in a compact versatile format that makes DSA applications feasible. The research primarily focuses on the 450-474 MHz land mobile radio (LMR) band, and several additional bands like the TV band and the 2.5-2.7 GHz band. However, the research methodology and techniques are broadly applicable to many more frequency ranges. The research has four main areas: (a) spectrum sensor design and measurements, (b) occupancy modeling, (c) communicating the modeling information in a compact form to secondary users to support DSA algorithms and protocols, and (d) tools and metrics for spectrum sharing favorability analysis. Three spectrum sensor platforms were employed in measurements – (1) a spectrum analyzer based Spectrum Observatory (SO) that was developed earlier, (2) a specially purposed software-defined radio (SDR) for measuring LMR channels, (3) and a high-speed and portable SO system based on a sensor called the RFeye. An SO continually measures RF data in a band at a high temporal resolution such that the channel switching activity is seen – like, transmitters turning on and off. Spectrum measurements of the individual RF channels in the 450-474 MHz LMR band and the two commercial bands are used to generate statistical traffic and occupancy models. Long-term measurement data is used to assess how stationary the channel is, and how often the model parameters need to be updated. The spectrum observatory supports a network of Secondary Users (SU) by communicating the traffic model parameters in a compact format to the SUs. The SUs share Primary User (PU) channels via DSA techniques. The DSA algorithms take advantage of the model parameters provided by the SO to maximize SU throughput with limited interference on the PU. The DSA coexistence techniques are evaluated via simulation. The simulation results including Spectrum Opportunity Accessed (SOA), SU throughput, and collision rates are then analyzed to provide an assessment of DSA-based spectrum sharing in that band. The main contribution of this dissertation is the aforementioned CBM procedure. The white spaces in the frequency and time domains, that is, the underutilized spectrum opportunities available for possible secondary use via DSA are automatically identified, as well as the frequency locations that are not conducive to DSA due to the presence of frequent primary licensee transmissions. In CBM, white spaces are referred to as ‘Holes’, and the licensed primary transmission frequencies as ‘Signals’. Useful information about the duty cycles and traffic patterns of incumbent users’ activity within possible secondary use channels is extracted and modeled. The model enables prospective secondary users of white spaces to predict the expected level of interference in any channel, which allows for channel ranking and optimal selection of DSA transmission parameters. The CBM model is describable by a tiered structure, where the first tier identifies the holes and signals; the second tier ranks the holes in terms of available bandwidth and incumbent duty cycle; and the third tier models the infrequent incumbent transmissions. With the three tiers of information, an SU can readily identify all the suitable DSA channels within the entire spectrum band. This essential summary information is retrieved as a “Hole Descriptor Object” (HDO) that is both compact and tractable. Empirical spectrum measurement data obtained from the three different SO platforms is used to test the performance of the CBM procedure in the 2500-2700 MHz frequency range that currently has WiMAX deployments, the TV white space band, and the 450-474 MHz LMR band in Chicago. Spectrum measurement data runs into hundreds of megabytes or gigabytes. As such, the raw information is not very applicable in practical wireless networks. The HDO objects on the other hand are compact and only kilobytes in size. The HDO objects contain all the useful and applicable information necessary for any smart radio (primary or secondary) to select transmission parameters like frequency of operation and bandwidth, so that it can efficiently operate. Thus, the advantage of the CBM procedure is that it summarizes gigabytes of raw spectrum measurements in a usable compact format that can be directly used by practical smart radios to operate using DSA paradigms. Another advantage of CBM is that it is comprehensive and automatically identifies all holes and signals. The research findings are of interest and value to a variety of Federal and Commercial entities. The models and relevant model parameters for public safety radio in the LMR band have been provided on request to the Public Safety and Homeland Security Bureau of the Federal Communications Commission (FCC). The DSA feasibility analysis methodology is of great national economic interest based on the contents of the PCAST report. The PCAST report recommends finding 1000 MHz of federal frequencies to be allocated for shared commercial and federal use. However, the technology for doing so and identifying the suitable bands requires measurements of actual spectrum usage, modeling the occupancy and existing traffic activity, and assessing DSA feasibility – these are important research aspects, and all of which are addressed in this dissertation. The results are of crucial importance to policy makers like the FCC and NTIA who will ultimately make the spectrum allocations decisions. A future network of commercial DSA SU radios operating in a shared band is likely to need access to a system to obtain live information about PU activity to optimally operate in the band with high throughput and low interference. The overall system, based on the CBM procedure and HDO objects, proposed in this thesis describes a framework for providing this information as a service to DSA networks, and hence the work is also of practical relevance to radio system designers.
Ph.D. in Electrical Engineering, July 2014
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Title: LASER MICROMACHINING, SINTERING, AND LASER-INDUCED PLASMA DEBURRING
Creator: Gao, Yibo
Date: 2013, 2013-12
Description: Lasers can provide non-mechanical-contact, localized and concentrated energy input to materials with controlled durations and high spatial...
Show moreLasers can provide non-mechanical-contact, localized and concentrated energy input to materials with controlled durations and high spatial resolutions down to a few microns or less. Therefore, lasers have more and more applications in manufacturing and materials processing, such as laser micromachining (which is to create micro-scale features through laser-induced material removal) and laser sintering. Despite the previous research work in the literature, many laser-based manufacturing and materials processing areas still require lots of further research work. Specifically, the following topics will be investigated in the research work in this thesis: nanosecond-pulsed laser ablation of silicon carbide at an infrared wavelength, nanosecond laser-induced plasma deburring, two-step nanosecond laser surface texturing, and the fabrication of carbon nanotube (CNT)-ceramic composites through the laser sintering process.
PH.D in Mechanical and Aerospace Engineering, December 2013
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Title: FUNCTIONAL ANALYSIS OF UBIQUITIN-LIKE PROTEIN 4A
Creator: Zhao, Yu
Date: 2015, 2015-12
Description: Ubiquitin-like protein 4A (Ubl4A) was identified as a housekeeping gene at X chromosome. It involves in the guided entry of tail-anchored (GET...
Show moreUbiquitin-like protein 4A (Ubl4A) was identified as a housekeeping gene at X chromosome. It involves in the guided entry of tail-anchored (GET) protein pathway in which tail-anchored (TA) proteins are transported to endoplasmic reticulum (ER). However, Ubl4A also involves other functions not related to GET pathway, such as tumor suppression and DNA damage-mediated apoptosis. Up to date, the function of Ubl4A in mammals is still largely unknown. We found that either overexpression or knockdown of Ubl4A promoted cell death in cell culture system. Using an in vivo genetic knockout system, we found that Ubl4A knockout mice displayed a high neonatal mortality and had a defect in glycogen synthesis, which is mainly controlled by a key protein kinase Akt. Loss of Ubl4A resulted in the impairment of insulin-induced Akt translocation to the plasma membrane, an essential step for Akt activation. We demonstrated that Ubl4A directly interacted with actin-related protein 2/3 (Arp2/3) complex, further accelerated Arp2/3 complex-dependent actin branching, thereby bringing Akt to proximity into the plasma membrane for activation. Furthermore, we showed that Ubl4A-mediated actin branching also played important roles in other cellular activities, such as formations oflamellipodia and filopodia, macrophage phagocytosis, wound healing, and neutrophil chemotaxis. These findings provide us a new insight into understanding the roles of Ubl4A in cellular function and a molecular basis for treatment of related human diseases.
Ph.D. in Biology, December 2015
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Title: APPLICATION-AWARE OPTIMIZATIONS FOR BIG DATA ACCESS
Creator: Yin, Yanlong
Date: 2014, 2014-07
Description: Many High-Performance Computing (HPC) applications spend a significant portion of their execution time in accessing data from les and they are...
Show moreMany High-Performance Computing (HPC) applications spend a significant portion of their execution time in accessing data from les and they are becoming increasingly data-intensive. For them, I/O performance is a significant bottleneck leading to wastage of CPU cycles and the corresponding wasted energy consumption. Various optimization techniques exist to improve data access performance. However, the existing general-purpose optimization techniques are not able to satisfy diverse applications' demands. On the other hand, the application-specific optimization pro- cess is usually a difficult task due to the complexity involved in understanding the parallel I/O system and the applications' I/O behaviors. To address these challenges, this thesis proposes an application-aware data access optimization framework and claims that it is feasible and useful to utilize applications' characteristics to improve the performance and efficiency of the parallel I/O system. Under this framework, an optimization may consist of several basic but challenging steps, including capturing the application's characteristics, identifying the causality of I/O performance degra- dation, and delivering optimization solutions. To make these steps easier, we design and implement the IOSIG toolkit as an essential system support for the default par- allel I/O system. The toolkit is able to pro le the applications' I/O behaviors and then generate comprehensive characteristics through trace analysis. With the help of IOSIG, we design several optimization techniques on data layout optimization, data reorganization, and I/O scheduling. The proposed framework has significant poten- tial to boost application-aware I/O optimization. The results prove that the proposed optimization techniques can significantly improve the data access performance.
Ph.D. in Computer Science, July 2014
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Title: COMMUNICATION AND COMPUTATION ARCHITECTURES FOR DISTRIBUTED WIRELESS SENSOR NETWORKS AND INTERNET OF THINGS
Creator: Yi, Won-jae
Date: 2017, 2017-07
Description: Real-time data communication has been viral since the era of the smartphone rose to prominence in this decade. All communications from human...
Show moreReal-time data communication has been viral since the era of the smartphone rose to prominence in this decade. All communications from human to human, from device to human, and from device to device are handled over the Internet connection either through a mobile Internet service provider or Wi-Fi, which enables information exchange including weather service, road traffic conditions, news alerts, package tracking notifications. By looking at different perspectives of the role of a smartphone, it reveals itself as an ideal device to mobilize critical user data to construct a real-time monitoring application such as in remote healthcare and home automation systems. Not only can the smartphone handle real-time data transmissions, but it can also handle real-time computations on the device itself by utilizing its embedded CPU. This dissertation is a comprehensive study of the investigation, exploration and experimentation on a real-time health monitoring system where quality of life can be improved when the conventional system may affect and hamper regular daily activities. The design flow of this system is based on the Internet connection where any device that is communicatively associated with the smartphone can be connected to the Internet. By utilizing the Android smartphone, not only does the system gain real-time data transmission capability, but it also obtains flexibility to communicate with different types of sensors and platforms through multiple wireless protocols. This system is highly adaptable to the currently trending Internet of Things (IoT) standards, where significantly increasing anticipation over its social impact, where it can assist populations in rural and distant areas for healthcare, day-to-day activity monitoring, and prevention against hazardous conditions for workers. The system architecture introduced in this research is focused on reconfigurability and compatibility of wireless sensors where they are independent from a certain platform in which sensors are not limited to medical devices but also detect movement, location, climate condition and any other sensor for analyzing the environment. Four major components are introduced in this research including wireless sensor nodes, a central sensor data processing and communication node, an Android application, and a central database server. They are discussed and explored to seek for solutions to improve and enhance features in the fundamental system design. Communication and computation processing capabilities are evaluated for all major components for practical usage of the system for different case studies. Also as a quantitative case study, a posture and fall detection system is presented which determines the patient's activities, medical conditions and the cause of an emergency event through the integration of all system architecture components. Adapting the IoT system is also explored in this dissertation by introducing a protocol standard to improve data transmission efficiency and to enable cross-platform compatibility of wireless devices. In addition to improving system efficiency, a study on data security issues and assessment on sensor data has been explored by implementing a proposed security scheme to each major component within the real-time mobile monitoring system. Also, a concept of Quality-of-Service (QoS) for mobile monitoring system using a wireless sensor network has been investigated to provide a solution to prioritize sensor data transmissions based on the results obtained from the sensor data assessment application. The proposed solutions can be either implemented on or under the application layer.
Ph.D. in Computer Engineering, July 2017
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Title: THE EUML-ARC PROGRAMMING MODEL
Creator: Marth, Kevin
Date: 2014, 2014-07
Description: The EUML-ARC programming model shows that the increasing parallelism available on multi-core processors requires evolutionary (not...
Show moreThe EUML-ARC programming model shows that the increasing parallelism available on multi-core processors requires evolutionary (not revolutionary) changes in software design. The EUML-ARC programming model combines and extends software technology available even before the introduction of multi-core processors to provide software engineers with the ability to specify software systems that expose abstract platform-independent parallelism. The EUML-ARC programming model is a synthesis of Executable UML, the Actor model, role-based modeling, split objects, and aspect-based coordination. Computation in the EUML-ARC programming model is structured in terms of semantic entities composed of actor-based agents whose behaviors are expressed in hierarchical state machines. An entity is composed of a base intrinsic agent and multiple extrinsic role agents, all with dedicated conceptual threads of control. Entities interact through their role agents in the context of featureoriented collaborations orchestrated by coordinator agents. The conceptual threads of control associated with the agents in a software system expose both intra-entity and inter-entity parallelism that is mapped by the EUML-ARC model compiler to the hardware threads available on the target multi-core processor. The hardware and software e ciency achieved with representative benchmark systems show that the EUML-ARC programming model and its compiler can exploit multi-core parallelism while providing a productive model-driven approach to software development.
Ph.D. in Computer Science, July 2014
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Title: DETECTING GNSS SPOOFING ATTACKS USING INS COUPLING
Creator: Tanil, Cagatay
Date: 2016, 2016-12
Description: Vulnerability of Global Navigation Satellite Systems (GNSS) users to signal spoofing is a critical threat to positioning integrity, especially...
Show moreVulnerability of Global Navigation Satellite Systems (GNSS) users to signal spoofing is a critical threat to positioning integrity, especially in aviation applications, where the consequences are potentially catastrophic. In response, this research describes and evaluates a new approach to directly detect spoofing using integrated Inertial Navigation Systems (INS) and fault detection concepts based on integrity monitoring. The monitors developed here can be implemented into positioning systems using INS/GNSS integration via 1) tightly-coupled, 2) loosely-coupled, and 3) uncoupled schemes. New evaluation methods enable the statistical computation of integrity risk resulting from a worst-case spoofing attack – without needing to simulate an unmanageably large number of individual aircraft approaches. Integrity risk is an absolute measure of safety and a well-established metric in aircraft navigation. A novel closed-form solution to the worst-case time sequence of GNSS signals is derived to maximize the integrity risk for each monitor and used in the covariance analyses. This methodology tests the performance of the monitors against the most sophisticated spoofers, capable of tracking the aircraft position – for example, by means of remote tracking or onboard sensing. Another contribution is a comprehensive closed-loop model that encapsulates the vehicle and compensator (estimator and controller) dynamics. A sensitivity analysis uses this model to quantify the leveraging impact of the vehicle’s dynamic responses (e.g., to wind gusts, or to autopilot’s acceleration commands) on the monitor’s detection capability. The performance of the monitors is evaluated for two safety-critical terminal area navigation applications: 1) autonomous shipboard landing and 2) Boeing 747 (B747) landing assisted with Ground Based Augmentation Systems (GBAS). It is demonstrated that for both systems, the monitors are capable of meeting the most stringent precision approach and landing integrity requirements of the International Civil Aviation Organization (ICAO). The statistical evaluation methods developed here can be used as a baseline procedure in the Federal Aviation Administration’s (FAA) certification of spoof-free navigation systems. The final contribution is an investigation of INS sensor quality on detection performance. This determines the minimum sensor requirements to perform standalone GNSS positioning in general en route applications with guaranteed spoofing detection integrity.
Ph.D. in Mechanical and Aerospace Engineering, December 2016
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Title: Optimal Behavior Modeling and Analysis of Electricity Market Participants
Creator: Li, Jie
Date: 2012-04-27, 2012-05
Description: n restructured electricity power markets, competition among market participants is a key issue of concern for both the ISO (Independent System...
Show moren restructured electricity power markets, competition among market participants is a key issue of concern for both the ISO (Independent System Operator) and the market participants themselves. This dissertation analyzes the market behavior of both the generation side and demand side participants, and provides solution guidelines for devising effective competition strategies for market players’ profit maximization objectives. Generation side is the most competitive part in the electricity market with the unbundling of generation, transmission and distribution. Acting as self-interested entities, GENCOs (Generation Companies) are seeking effective and computationally efficient methodology for generation resource scheduling, while keeping its financial risks at acceptable levels when constituting bidding strategies. To help GENCOs achieve such goal, this dissertation propose a game theory based supply function like bidding model to construct the optimal bidding strategies for GENCOs in both energy and ancillary service markets. On the demand side, demand participation in the electricity market has already been advocated for a long time for its benefit to the entire market and the society as a whole. This dissertation focuses on a specific large electricity consumer type – Internet Data Center (IDC). By analyzing the unique energy consumption pattern for different IDC applications, this dissertation devises effective electric demand management solution for IDCs to conserve electricity energy consumption and cut electric bill, and quantifies the demand response effect of IDC on the electricity market.
Ph.D. in Electrical Engineering, May 2012
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Title: Development and Application of an Occupational Odor Hazard Index
Creator: Wang, Tingting
Date: 2011-04-24, 2011-05
Description: Odors emitted from wastewater treatment and sludge processing facilities may lead to employee complaints regarding discomfort, stress or...
Show moreOdors emitted from wastewater treatment and sludge processing facilities may lead to employee complaints regarding discomfort, stress or disease, and affect productivity and worker turnover in Water Reclamation Plants (WRPs). This study reports and assesses a comprehensive method that estimates the odor perception and associated hazards from exposures to odors in a post-digestion dewatering building in a WRP and its vicinity areas. An Odor Reference Concentration (ORfC) is developed as an index of acceptable odor level. This index is applied to ensure that the majority of building occupants (80 percent or more) do not perceive the odor. This index is developed to fill the lack of a uniform standard and method to assess hazard of exposed individuals to odors in occupational environments and to regulate odor exposures.
A comprehensive odor and odorant concentration database was formulated by a monitoring study in the occupational environment of a post-digestion dewatering building. The presence of odorants in the building are at concentrations below occupational exposure limits but higher than odor detection threshold values. This finding indicates that reducing odorant concentrations below exposure limits does not assure an odor-free environment. A model is formulated and validated for this dewatering building associating odor perception with concentrations of total sulfur compounds and relative humidity and is used for prediction of indoor odor concentrations under various conditions. Odor and odorant emission rates as the strength of sources are input variables of the indoor air quality model. In this study, odor and odorant emission rates from freshly dewatered biosolids in a dewatering building were measured using two widely used dynamic methods: the USEPA flux chamber and wind tunnel, and results from the two methods are not significantly different. Comparison of the two methods indicates that both methods can be used to estimate odor and odorant emission rates but the most effective and efficient method depends on prevailing environmental conditions. The ORfC established based on the comprehensive odor and odorant concentration database for this dewatering building is 13D/T (dilution to threshold). This index is used to evaluate seven control strategies recommended to reduce odor levels. If indoor odor concentrations in the occupational environment exceed the ORfC, then the hazard of odor exposures is unacceptable. Deterministic results of this study indicate that if appropriate control strategy is applied, odor concentration in the dewatering building would reach to below levels that cause unnecessary stress and other effects. The control strategy focus of this work is reduction of the indoor odor perception. But indoor control strategies must not cause outdoor odor problems to surrounding residential areas. Therefore, the potential impact of the control strategy recommended is also investigated in this thesis using the US EPA recommended air dispersion modeling AERMOD. Predictions of hydrogen sulfide concentrations at surrounding areas of the plant indicate that only one strategy, which proposes to add a new exhaust system in the dewatering building, would cause the ambient hydrogen sulfide concentration to be 7% higher than the odor detection threshold; other six strategies would not induce odor annoyance to surrounding areas. Acute and long-term ambient hydrogen sulfide exposure limits based on human health and irritation effects would not be violated under any of the seven control strategies.
Ph.D. in Environmental Engineering, May 2011
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Title: INVESTIGATION OF ANION EXCHANGE MEMBRANES FOR ELECTROCHEMICAL ENERGY CONVERSION AND STORAGE SYSTEMS
Creator: Wang, Lihui
Date: 2017, 2017-05
Description: The alkaline stability of poly (arylene ether) backbones in anion exchange membranes (AEMs) derivatized with quaternary benzyl N, N-...
Show moreThe alkaline stability of poly (arylene ether) backbones in anion exchange membranes (AEMs) derivatized with quaternary benzyl N, N- dimethylhexylammmonium (DMH+) and trimethylammonium (TMA+) cation groups were investigated in poly (2,6- dimethyl 1,4-phenylene) oxide (PPO) and Udel® polysulfone (PSF) polymers. Previous studies have demonstrated that quaternary ammonium and phosphonium groups trigger backbone degradation in commercially available poly (arylene ether)-based AEMs, despite the base polymers’ resilience to alkaline solutions. Herein, I demonstrate that the electron withdrawing or donating character in the poly (arylene ether) backbone ultimately dictates whether the prepared AEMs will become brittle in alkaline media due to cation-triggered backbone degradation (Arges, Parrondo, Johnson, Nadhan, & Ramani, 2012a; Christopher G. Arges, Lihui Wang, Javier Parrondo, & Vijay Ramani, 2013). Mitigation of cation-triggered backbone degradation was only achieved when electron withdrawing substituents (not including the cation), such as sulfone or bromine, were eliminated from the polymer backbone (or, alternately, when electron donating groups were present). Hence, PPO AEMs prepared through chloromethylation, rather than free radical bromination, were resistant to backbone hydrolysis in alkaline media because each cation-functionalized repeat unit had two electron-donating methyl groups rather than a single methyl group. This study presents some design rules for preparing mechanically stable poly (arylene ether) AEMs from low cost, commercially available polymers for alkaline electrochemical devices.
Ph.D. in Chemical Engineering, May 2017
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Title: THE EFFECT OF FLOW ON MICROPARTICLE TRANSPORT AND THE ROLE OF MICROPARTICLES IN THROMBOSIS
Creator: Lee, Ying-hui
Date: 2012-11-27, 2012-12
Description: Elevated monocyte/macrophage-derived microparticles (MPs) have been found to correlate with thrombotic complications. These MPs carry tissue...
Show moreElevated monocyte/macrophage-derived microparticles (MPs) have been found to correlate with thrombotic complications. These MPs carry tissue factor (TF), the principal coagulation pathway initiator, as their parental cells and expose anionic phospholipid phosphatidylserine (PS), which can promote thrombin generation and fibrin formation. During thrombus development, MPs may be delivered to the injured/dysfunctional vascular endothelium or biomaterial surfaces and influence the process of thrombosis. MPs are submicron membrane vesicles that may have increased transport and/or binding capabilities compared to platelets or other cell types due to their decreased size and their higher Brownian diffusion. MPs and their surface molecules can be delivered to surfaces, either biological or prosthetic, and alter the local environment. Little is known of the mechanisms by which MPs are transported to and impart their biological activity on surfaces, especially in blood. Such a transfer of activity will depend on the ability of MPs to be transported to the surface, the strength of adhesion of the MPs on the surface and the nature of the activity/host interaction. In the present study, physical and biological properties of MPs generated from macrophage-like cell lines by endotoxin stimulation were characterized, the transport of MPs to surface by flow was investigated, and the import biological activity on surfaces was elucidated. We observed that the deposition of MPs suspended in buffer on glass surfaces was strongly shear-dependent using a well-defined parallel plate flow chamber. The diffusivity coefficients of MPs at shear rate ranges ranging from 100 to 3200 s-1 were determined from the classical mass transport equation proposed by Leveque and the values were found to be of the same order of magnitude as predicted by Brownian xi diffusion. MPs non-specific attachment to glass was dominated by electrostatic interactions; this was verified by changing the surrounding ionic strength of the suspending solution. In addition to shear rate, red blood cells (RBCs) also influenced MP adhesion due to the complex movement of RBCs. Such movement has been shown to enhance the adhesion of platelets (1-2 micron size cells) to surfaces in flowing blood. MP lateral transport was enhanced at low concentrations of RBCs and reduced at higher concentration of RBCs. The reduction of MP deposition was due to the competition for surface binding sites between the two populations of MPs. The two types of MPs studied here, those produced by macrophages after endotoxin stimulation and those produced by RBCs during experimental preparation (repeated centrifugal washing) have the capability of nonspecific binding to artificial surfaces in a competitive manner. Finally, we demonstrated that the amount of adherent MPs on surfaces influenced fibrin formation via both a TF-dependent and a negatively charged phospholipid pathway. These findings suggest that procoagulant MPs may modulate thrombotic events under certain conditions, especially in MP-associated diseases. The knowledge of the effects of flow on MP transport and the influence of increased MPs on thrombosis may provide novel insights for the transfer of biological activity to relatively passive surfaces.
PH.D in in Biomedical Engineering, December 2012
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Title: ULTRASONIC RANGING AND INFRARED DEPTH PROFILING FOR 3D IMAGE RECOl'STRUCTION AND SCENE ANALYSIS
Creator: Jia, Weldi
Date: 2013, 2013-07
Description: This doctoral work cannot be done without the help, support and dedication of numerous people. First of all, I will give my great thanks to my...
Show moreThis doctoral work cannot be done without the help, support and dedication of numerous people. First of all, I will give my great thanks to my advisor Dr. Jafar Saniie, who is patient, fundamental and knowledgeable in providing advices, suggestions and guidance to all my six years' study. I would like to express my sincere thanks for his encouragement and nancial support during my study. I will never forget the days and nights he spent with me doing research work in the ECASP research lab. His spirit of carefully searching, friendly talking and knowledgeably thinking stays in my mind forever. My gratitude extends to my committee members, Dr. Anjali, Dr. Moderes and Dr. Oruklu. Also, I would like to give my thanks to my colleagues and friends, especially the people in ECASP research lab, Won-Jae, Sufeng, Thomas, Spenser and Pramod. Their kindness and powerful knowledge in di erent elds help me enhance my work so much. I will never forget the days debugging programs with them and the days we cheered for our success. I would like to dedicate this thesis to my family, especially to my grandfather who just passed away but gave me nancial support and advices from childhood till now, my father who is not able to speak after an accident during my study, my mother who is taking care of my father herself during the past six years, and my wife Wenhui Liu, who encouraged and helped me living in the United States. I promise that I will use what I learned from here to change the world and their constant support of my academic ventures from the beginning to the present would be valuable. Thank you Grandpa, rest in peace in heaven.
PH.D in Electrical Engineering, July 2013
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Title: EFFICIENT AND FAIR RESOURCE ALLOCATION FOR OFDMA NETWORKS
Creator: Alavi, Seyed Mohamad
Date: 2012-11-26, 2012-12
Description: In Orthogonal Frequency Division Multiple Access (OFDMA) systems, resources, including subcarriers, bits and power, need to be adaptively...
Show moreIn Orthogonal Frequency Division Multiple Access (OFDMA) systems, resources, including subcarriers, bits and power, need to be adaptively allocated to users in order to improve spectral efficiency, increase capacity, and reduce power consumption, while satisfying the Quality of Service (QoS) requirements for users. Most of the previous works concentrate on satisfying rate and power requirements, however providing delay requirement is also necessary, especially with increasing demand on delay-sensitive applications. We first model the resource allocation problem as a cross-layer optimization problem considering the constraints on bit error rate (BER), data rate, total power, as well as delay. We first develop a nonlinear optimization model, which generally requires high computation complexity. To consider a more realistic scenario, we take into account imperfect Channel State Information (CSI) due to estimation errors or channel feedback delay, and incorporate the imperfect CSI into the optimization problem formulation. We then derive the solution through a dual decomposition method. Due to the duality gap between the original and dual optimizations, we convert the non-linear optimization to an equivalent linear formulation so that an exact solution can be obtained. To further reduce the complexity, we develop a heuristic algorithm to provide a solution close to the optimum. Then, we study the notion of fairness in the context of resource allocation. In particular, cooperative game theory can be applied to OFDMA networks for fair resource allocation. We apply two cooperative games, Non-Transferable Utility (NTU) game and Transferable Utility (TU) game, to provide fairness in OFDMA networks. In NTU game, fairness is achieved by defining appropriate objective function, while in TU game, fairness is provided by forming the appropriate network structure. For NTU game, we analyze the Nash Bargaining Solution (NBS) as a solution of NTU game taking into account CSI and Queue State Information (QSI). In a TU game, we show that coalition among subcarriers to jointly provide rate requirements leads to better performance in terms of power consumpviii tion. We show that although NTU and TU games are modeled as rate adaptive and margin adaptive problems, respectively, but both solutions provide a fair distribution of resources with minimum fairness index of 0.8. Although NBS can provide fairness, the fairness is not from user perspective. In competitive fairness, which is based on auction theory, each user is responsible for his/her own action. A distributed allocation of resources in OFDMA networks is studied through auction theory. A combinatorial auction is formulated in which the users’ utility enforce the truthful resource demands. Since the original problem is NP hard, a method based on simulated annealing applied to find near-optimum results. Then, we turn our attention toward a more complicated scenario of multicell OFDMA networks. A combinatorial auction, which takes into account the interference from adjacent cells is presented. Auction objective is to minimize the interference, while power of users is limited. Due to the complexity of original problem, we apply a heuristic approach, in which the bids are ordered based on the linear programming approximation of combinatorial auction, and then local improvements are made in the order of bids. Our iterative approach along with the proposed load control scheme provides fair distribution of resources to the users, regardless of their position in the cell. Finally, we propose a comprehensive auction in OFDMA network. We present an auction framework for allocation of subcarriers, in which winner pays monitoring and entry fees, in addition to the price which he is paying for the allocated subcarrier. We prove that in our framework users will avoid bidding for the subcarriers where they have a relatively low chance of winning. We obtain optimal bidding strategy based on Bayesian Nash Equilibrium (BNE) in which users are maximizing their net profit. In a Fractional Frequency Reuse (FFR) implementation of frequency planning, we will find a focal distance which classifies the users into cell-center and cell-edge users. It is shown that the focal distance increases as the interference decreases.
PH.D in Electrical Engineering, December 2012
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Title: STRUCTURE AND FUNCTION OF NATIVE AND EDITED DYSTROPHIN RODS
Creator: Sahni, Neha
Date: 2011-05-10, 2011-05
Description: The purpose of this study is to examine the biophysical properties of the rod region of the dystrophin protein. This is important due to the...
Show moreThe purpose of this study is to examine the biophysical properties of the rod region of the dystrophin protein. This is important due to the severity of the disease Duchenne Muscular Dystrophy, (DMD), which is associated with the malfunction of this protein. DMD is one of the most serious single gene genetic defects of man. This rod region consists of a number of repeat motifs called spectrin type repeats or STRs. The thermodynamical and biochemical stability analysis shows, which single motifs are unstable on their own and which ones become more stable when linked to their appropriate tandem neighbors. This knowledge will impact strategies to produce modified mini dystrophins for gene therapy. Exon skipping therapy is an emerging approach to treat such genetic diseases. This is done by the administration of modified antisense oligonucleotides, AONs, which can interfere with exon splicing process and eliminate certain exons from the mature transcript. Furthermore, the rod region has a number of ancillary functions, such as providing secondary binding sites for actin, neuronal NO synthetase and phospholipids, which may be adversely perturbed by the edits.
Ph.D. in Biological, Chemical, and Physical Sciences, May 2011
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Title: NEW TOOLS FOR JET ANALYSIS IN HIGH ENERGY COLLISIONS
Creator: Duffty, Daniel
Date: 2015, 2015-05
Description: Our understanding of the fundamental interactions of particles has come far in the last century, and is still pushing forward. As we build...
Show moreOur understanding of the fundamental interactions of particles has come far in the last century, and is still pushing forward. As we build ever more powerful machines to probe higher and higher energies, we will need to develop new tools to not only understand the new physics objects we are trying to detect, but even to understand the environment that we are searching in. We examine methods of identifying both boosted objects and low energy jets which will be shrouded in a sea of noise from other pasts of the detector. We display the power of boosted-b tagging in a simulated W' search. We also examine the effetc of pile up on low energy jet reconstructions. For this purpose we develop a new priority-based jet algorithm, "p-jets", to cluster the energy that belongs together, but ignore the rest.
Ph.D in Physics, May 2015
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Title: PIEZO-BARKHAUSEN PULSE SIGNAL ANALYSES (BPSA) AND DETERMINATION OF THE FATIGUE LIFE OF AISI-1018 STEEL NEAR THE ENDURANCE LIMIT
Creator: Nunez-moreno, Federico Alejandro
Date: 2014, 2014-05
Description: A series of fatigue tests were performed on two different types of steels named Steel A (annealed and decarbed AISI-1018 steel), and Steel B ...
Show moreA series of fatigue tests were performed on two different types of steels named Steel A (annealed and decarbed AISI-1018 steel), and Steel B (annealed and polished AISI-1018 steel), carried out to separation or to a maximum of 10,000,000 cycles (which was taken to be equivalent to infinite life). Strain levels ranging from 0.0014 in/in (0.0014mm/mm) down to 0.0008in/in (0.0008mm/mm) were used to execute all experimental load tests at a stress ratio R=-1 (complete reversal). An MTS machine was used for these trials. At the same time, magnetic fields and piezo-Barkhausen pulses were recorded by means of a flux gate magnetometer and a copper coil connected to a series of signal filters and amplifiers. Results were used to construct the classical S-N Whöler curve for both steels, as well as in exhibiting the behavior of the magnetic parameters (magnetic excursions, dominant frequencies of the magnetic signals) coupled to the fatigue lives of the samples tested. To describe such couplings, a set of correlations were introduced among the monitored variables as functions of testing time and applied strain. Also, a fractography analysis of the crack patterns using a scanning electron microscope was performed to represent statistically the geometry of “dimples” and fatigue striations from the inception of the crack, until the formation of a shear lip at the final stages of the crack. It was found that the magnitude of the mean amplitude of the piezo-Barkhausen pulses at early stages of the test is correlated to a mid-level energy of cracking, and thus explains the geometry of fatigue striations near the initiation of the crack at higher strain levels, compared to the geometry of the fatigue striations at lower strain levels. x xvi A joint analysis of the amplitudes of the magnetic excursions recorded in time, and the dominant frequencies of the magnetic signals were found to be discriminators of the elastic and plastic behavior of both types of steel. Furthermore the observed magnetic parameter variations determined in a clear way the endurance limit for each type of steel; these values also are in agreement with the strain level for which fatigue lives were greater than 10,000,000 cycles. Based on these results a “bell analogy” for interpreting the fatigue behavior is introduced. Bridge engineering applications and further research is also discussed.
PH.D in Civil Engineering, May 2014
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Title: CYBER-PHYSICAL SYSTEM FOR A WATER RECLAMATION PLANT: BALANCING AERATION, ENERGY, AND WATER QUALITY TO MAINTAIN PROCESS RESILIENCE
Creator: Zhu, Junjie
Date: 2015, 2015-07
Description: Aeration accounts for a large fraction of energy consumption in conventional water reclamation plants (WRPs). Although process operations at...
Show moreAeration accounts for a large fraction of energy consumption in conventional water reclamation plants (WRPs). Although process operations at older WRPs can satisfy effluent permit requirements, they typically operate with excess aeration. More effective process controls at older WRPs can be challenging as operators work to balance higher energy costs and more stringent effluent limitations while managing fluctuating loads. Therefore, understandings of process resilience or ability to quickly return to original operation conditions at a WRP are important. A state-of-art WRP should maintain process resilience to deal with different kinds of perturbations even after optimization of energy demands. This work was to evaluate the applicability and feasibility of cyber-physical system (CPS) for improving operation at Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) Calumet WRP. In this work, a process model was developed and used to better understand the conditions of current Calumet WRP, with additional valuable information from two dissolved oxygen field measurements. Meanwhile, a classification system was developed to reveal the pattern of historical influent scenario based on cluster analysis and cross-tabulation analysis. Based on the results from the classification, typical process control options were investigated. To ensure the feasibility of information acquisition, the reliability and flexibility of soft sensors were assessed to typical influent conditions. Finally, the process resilience was investigated to better balance influent perturbations, energy demands, and effluent quality for long-term operations. These investigations and evaluations show that although the energy demands change as the influent conditions and process controls, in general, aeration savings could be up to 50% from the level of current consumption; with a more xix complex process controls, the saving could be up to 70% in relatively steady-state conditions and at least 40% in relatively challenging transient conditions. The soft sensors can provide reliable and flexible performance on target predictions. The plant can still maintain at a similar level of process resilience after 50% aeration saving, even during long-term perturbations. Overall, this work shows that it is well feasible to provide more cost-effective operations at the Calumet WRP, and meanwhile influent perturbations, effluent quality, and process resilience are well in balance. Keywords: Energy, aeration, effluent quality, perturbation, resilience, water reclamation plant.
Ph.D. in Environmental Engineering, July 2015
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