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Title: SURVIVABLE OPERATION OF THREE PHASE AC DRIVES IN WIND GENERATOR SYSTEMS
Creator: Shi, Xiaodong
Date: 2012-04-06, 2012-05
Description: Recent years have seen significant popularity in the use of wind generators owing to the depletion of natural resources and growing concerns...
Show moreRecent years have seen significant popularity in the use of wind generators owing to the depletion of natural resources and growing concerns about our environment. However, this development has raised issues concerning reliability of the wind turbine components. Among these faults, failure of current sensors is one of most common faults that can bring the wind generator to a standstill and lead to reduction in power yield. In addition, unscheduled maintenance often results in longer downtime and causes reduction of wind plant availability especially for those wind turbines located offshore or in remote areas. This dissertation proposes a survivable drive method to continue to operate the wind turbine in spite of current sensor failure. One of the common control strategies for the optimal of three-phase AC generators is vector control. Therefore, vector control method is implemented in this dissertation for both induction machine and Brushless PMSM. In order to achieve survivability when current sensor fault happens, a simple and effective method which doesn’t rely on current feedbacks is required as a backup control strategy. For this purpose, a digital control strategy is proposed for an induction machine and a Brushless PMSM. In addition, a current sensor failure detection method is designed to trigger the transition and a smooth transition method (only for induction machine) is implemented to ensure the smoothness of the control transition without stopping the system. Simulation and experimental results have been presented to prove feasibility and demonstrate the effectiveness of the proposed strategy.
Ph.D. in Electrical Engineering, May 2012
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Title: EVALUATION OF COMPUTER ALGORITHMS FOR THE ANALYSIS AND RECONSTRUCTION OF CARDIAC IMAGES
Creator: Parages, Felipe M.
Date: 2017, 2017-05
Description: In the medical imaging field, image processing algorithms must be evaluated by measuring performance at some clinically-relevant task of...
Show moreIn the medical imaging field, image processing algorithms must be evaluated by measuring performance at some clinically-relevant task of interest (i.e. task-based quality assessment). This dissertation relies on the task-based paradigm to evaluate motion-estimation and image-reconstruction methods, respectively, for two cardiac-imaging modalities, namely: cardiac-gated tagged Magnetic Resonance Imaging (MRI), and Single Photon Emission Computerized Tomography for Myocardial Perfusion Imaging (SPECT-MPI). First, a task-based approach is followed to evaluate three motion-estimation methods for clinical cardiac-gated tagged MRI, namely: non-rigid registration using a Deformable Mesh Model (DMM), Strain from Unwrapped Harmonic Phase (SUPHARP), and Feature-Based (FB) algorithms. More specifically, the goal is to quantify and rank their performances at both detection and estimation tasks. For detection, methods are evaluated per their ability to discern between normal and abnormal motion patterns in known cardiomyopathies (e.g. hypertension and mitral regurgitation). For estimation tasks, methods are evaluated per their accuracy at estimating several rotation/twist and strain features of clinical interest; since true values for these features are generally unknown, a statistical Regression Without Truth (RWT) model is adopted, which does not assume the existence of a “gold-standard” method to use as a ground-truth reference. Moreover, the RWT model provides with an objective figure-of-merit that allows ranking methods in absolute fashion. Second, a novel anthropomorphic Model Observer (MO) is proposed for optimization of SPECT-MPI reconstruction algorithms such as Filtered Back-projection (FBP) and Ordered-subsets Expectation Maximization (OSEM). MOs are computer models that aim to mimic the performance of human readers (typically radiologists) at some clinically relevant task of interest. The proposed MO is based on supervised machine-learning classification, for the diagnostic tasks of detection, localization and assessment of perfusion defects. The MO is trained using an ensemble of synthetic cases whose perfusion were scored (i.e. labeled) by human specialists. The trained MO is subsequently applied on images not read by humans (both synthetic and clinical), aiming to predict their diagnostic scores. Results show that the proposed MO accurately predicts human diagnostic performances. Furthermore, it generalizes well to new images not used during training, not only from different reconstruction algorithms, but also from synthetic to clinical cases.
Ph.D. in Electrical and Computer Engineering, May 2017
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Title: NEW CLASS OF EMBEDDED SPACE TIME BLOCK CODE FOR MIMO WIRELESS COMMUNICATION SYSTEMS
Creator: Norouzi, Mandana
Date: 2015, 2015-12
Description: In this thesis a new class of space time block codes is proposed. Space time code is one solution for the multipath fading communication...
Show moreIn this thesis a new class of space time block codes is proposed. Space time code is one solution for the multipath fading communication systems that limit the reliability and data rate of the communication link. By organizing multiple antennas at the transmitter and receiver, multipath fading can be turned into an advantage, allowing for greater reliability and higher data rates than would otherwise be possible. Without any extra cost of bandwidth, rate and reliability benefits can be achieved. Therefore, having multiple antenna technology is a foundation of current and future wireless systems. In space time coding information, symbols are encoded across two dimensions, the spatial dimension and the time dimension. Information that is transmitted corresponds to multiple antennas at the transmitter and to multiple signaling intervals. In this thesis, we consider the problem of designing a new class of linear space time block codes, in which the information symbols are linearly combined to form a twodimensional code matrix, wherein the rows of the code word matrix correspond to transmission across multiple antennas, and the columns of the matrix correspond to transmission in different time slots. The proposed space time code matrix is achieved based on eigenvalue decomposition (EVD) of the circulant, normal matrix and inverse fast Fourier transform definition (IFFT). These classes of codes have better performance with respect to symbolerror rate (SER) in comparison with other proposed linear space time code matrices in the literature. The proposed code has full rate and embedded diversity. The concept of embedded diversity has been defined in this research. According to that definition ourdesign supports embedded diversity and also has less decoding complexity at the receiver side. The proposed code has been applied to a relay network where nodes do not have four transmit antennas. In this thesis, performance of the code has also been evaluated when the receiver must rely on a noisy, imperfect, estimate of the channel. Channel estimation has been applied based on pilot sequence transmission. A group decodable full rate and full diversity space time block code also has been proposed for two transmit antennas and four time slots, which is applicable to the LTE-Advanced system. This new design also provides full diversity and full rate.
Ph.D. in Electrical Engineering, December 2015
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Title: RADAR AND COMMUNICATION CO-DESIGN: A CONSTANT ENVELOPE RADCOM SYSTEM
Creator: Testi, Nicolo
Date: 2014, 2014-12
Description: NO ABSTRACT
Ph.D. in Electrical and Computer Engineering, December 2014

Title: ELECTRIC-HYDRAULIC HYBRID ENERGY STORAGE SYSTEM FOR ELECTRIFIED TRANSPORTATION
Creator: Niu, Geng
Date: 2017, 2017-07
Description: Environmental issues and fossil fuel depletion push the evolution of transportation and electrified transportation into the most likely next...
Show moreEnvironmental issues and fossil fuel depletion push the evolution of transportation and electrified transportation into the most likely next generation. However, there are several challenges in electrification with the major concerns involving the energy storage system. A hybrid energy storage system may provide an opportunity to improve the energy storage system of applications in transportation electrification. Hydraulic systems have been a mature technology for a long time and this study proposes a hydraulic add-on for electric vehicles. The high power density of a hydraulic accumulator could absorb high frequency regenerative braking and support battery discharging during acceleration, which will extend the driving range and reduce the current stress of the battery pack. Several models and controls have been created to evaluate hydraulic add-ons in di↵erent applications. The simulation results show a roughly 30% current stress drop and up to 25% energy saving (Wh/km) on average for city buses and delivery trucks over di↵erent driving cycles. A scaled down prototype vehicle with a novel electric hydraulic hybrid powertrain based on a go-kart chassis was built to perform road tests to validate the simulations results.
Ph.D. in Electrical Engineering, July 2017
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Title: ADVANCED BASE DRIVERS FOR SILICON CARBIDE BJTs
Creator: Pozo Arribas, Alejandro
Date: 2017, 2017-07
Description: This thesis focuses on the optimization of base drivers for SiC BJTs and presents a novel driver topology that targets minimum power...
Show moreThis thesis focuses on the optimization of base drivers for SiC BJTs and presents a novel driver topology that targets minimum power consumption. SiC BJTs have been studied for over a decade, during which time, they have been proven to have superior performance than Si IGBTs and even other normally-off SiC devices such as MOSFETs. Despite this, SiC BJTs are the least popular among the family of SiC power switches. As current controlled devices, BJTs require a continuous sup- ply of current through the base during the on-time. And, even though current gains over 100 have been reported, the base current required translates into a considerable amount power consumed by its driver, compared to its competitors. This power can affect the overall efficiency of a converter if the driver circuit is not designed properly. Since, the driver represents a key system for the success of SiC BJTs as power semiconductor devices, this thesis conducts a comprehensive evaluation of previous solutions and an analysis of the driver power losses to identify the optimal driver configuration. As a conclusion of this study, a novel topology is proposed, designed and built for its latter validation through experimental tests. The proposed solution allows the replacement of a SiC MOSFET or Si IGBT and driver with a SiC BJT and driver without the need of a current sensor or a dedicated DSP/FPGA. The driver power consumption is minimized with a proportional base current design based on a MHz synchronous buck converter operating as a Class D amplifier. This switched mode power amplifier uses a reference signal to provide a voltage that causes a base current proportional to the instantaneous collector current. The reference signal is generated with a high bandwidth sensor that measures the instantaneous voltage drop across the BJT (vCE) during the on-time. Hence, current sensors are avoided. Different alternatives for a voltage sensor are discussed and analyzed through simulations and experimental results. Moreover, the use of vCE to estimate the instantaneous collector current makes the proposed driver a temperature-sensitive design. For the first time, a proportional base current driver generates a base current proportional to the instantaneous collector current taking into account the effect of temperature on the DC current gain. Moreover, all this is achieved with solely analog electronics in a standalone solution. A 1.5kW Boost converter was built to validate the proposed driver under different collector currents and operating temperatures. In order to show the performance improvement offered by the proposed solution, the same Boost converter was operated with a commercial base current driver. This exercise showed a reduction of the driver power consumption by up to a factor of 4 without affecting the efficiency of the Boost converter. The switching behavior of a SiC BJT operated with the proposed driver and some of its limitations are discussed. These have, in fact, motivated additional research to develop efficient, isolated MHz regulators for faster operating frequencies of the SiC BJT. In addition, a new over-current protection integrated into the proposed driver is suggested and tested with interrupt times of less than 500ns for a collector current of 50A.
Ph.D. in Electrical Engineering, July 2017
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Title: SECURITY AND PERFORMANCE OPTIMIZATION FOR WIRELESS COMMUNICATIONS
Creator: Wang, Qian
Date: 2012-04-13, 2012-05
Description: Today’s communication systems rely heavily on wireless technologies. The large scale proliferation of wireless technology brings with it a...
Show moreToday’s communication systems rely heavily on wireless technologies. The large scale proliferation of wireless technology brings with it a more serious concern for security since wireless communications introduce multiple avenues for attack and penetration into a network. This dissertation studies two important and fundamental problems in wireless communication security: secure secret key establishment and anti-jamming communication. This dissertation extends the current body of knowledge by proposing a suite of new and novel solutions to enhance and optimize the system performance. A comprehensive study including theoretical analysis and simulative evaluation shows that the proposed solutions can be applied in highly dynamic networking scenarios where traditional security mechanisms may not be sufficient by themselves. The first part of this dissertation develops a novel cooperative key generation protocol to facilitate high-rate key generation in narrowband fading channels, where two keying nodes extract the phase randomness of the fading channel with the aid of relay node(s). In particular, a theoretical upper bound and a more practical upper bound on the maximum secret key rate are successfully established. Numerical examples and simulation studies are also presented to demonstrate that the key rate can be improved by a couple of orders of magnitude compared to the existing physical layer based key generation approaches. The second part of this dissertation develops an adaptive uncoordinated frequency hopping (UFH) protocol for anti-jamming wireless communications. This section of the dissertation introduces the online optimization theory into the solution space and makes the thorough quantitative performance characterization possible for UFH-based anti-jamming communications. The optimality of the proposed algorithms is analytically proved under various message coding scenarios. Simulation results are presented demonstrating the jamming resilience of the learning-based UFH algorithm. The final part of this dissertation presents a jamming-resistant multi-radio multi-channel opportunistic spectrum access protocol for cognitive radio networks (CRNs), where the secondary sender and receiver adaptively choose their channels to operate to maximize the throughput. The convergence of the learning algorithm is investigated and an upper bound on the performance difference between the secondary sender and receiver’s optimal strategies is obtained. The simulation results in this section validate the theoretical analysis and show that even if facing a powerful jammer using myopic policy, the proposed design is still very effective and has strong resilience against jamming.
Ph.D. in Electrical Engineering, May 2012
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Title: 3D COMPRESSION ALGORITHMS AND SYSTEM-ON-CHIP DESIGN FOR ULTRASONIC IMAGING APPLICATIONS
Creator: Govindan, Pramod
Date: 2015, 2015-05
Description: Ultrasonic systems are widely used in imaging applications for nondestructive evaluation, quality assurance and medical diagnosis. These...
Show moreUltrasonic systems are widely used in imaging applications for nondestructive evaluation, quality assurance and medical diagnosis. These applications require large volumes of data to be processed, stored, and/or transmitted in real-time. Therefore, it is essential to compress the acquired ultrasonic radio frequency (RF) signal without inadvertently degrading desirable signal features. Signal fidelity, computational speed and resource utilization are the major parameters to be considered while designing the architecture for the compression algorithm. In this study, two algorithms for ultrasonic signal compression are analyzed based on: sub-band elimination using discrete wavelet transform; and decimation/interpolation using time-shift property of Fourier transform. Both algorithms offer high signal reconstruction quality with a peak signal-to-noise ratio (PSNR) between 36 dB to 39 dB for minimum 80% compression. The computational loads and signal reconstruction quality are examined in order to determine the best compression method in terms of the choice of DWT kernel, sub-band decomposition architecture and computational efficiency. Furthermore, for compressing a large amount of volumetric information, 3D compression algorithms are designed by utilizing the temporal and spatial correlation properties of the ultrasonic RF signals. The performance analysis indicates that the 3D compression algorithm presented in this study offers an overall 3D compression ratio of 95% with a minimum PSNR of 27 dB. Furthermore, the DWT based ultrasonic 3D data compression algorithm is implemented on a reconfigurable ultrasonic system-on-chip hardware platform targeted for real-time ultrasonic imaging applications. The reconfigurable platform allows analysis of multiple architectures to suit various applications. In this study, hardware andtemporal and spatial correlation properties of the ultrasonic RF signals. The performance analysis indicates that the 3D compression algorithm presented in this study offers an overall 3D compression ratio of 95% with a minimum PSNR of 27 dB. Furthermore, the DWT based ultrasonic 3D data compression algorithm is implemented on a reconfigurable ultrasonic system-on-chip hardware platform targeted for real-time ultrasonic imaging applications. The reconfigurable platform allows analysis of multiple architectures to suit various applications. In this study, hardware and software architectures of the 3D ultrasonic compression algorithm implemented on Xilinx Zynq all programmable system-on-chip platform are discussed, along with the analysis of computational performance. Both implementations provide a high signal compression ratio of about 98% with good quality signal reconstruction. This study demonstrates that, compressing 33 MBytes of experimental ultrasonic 3D data into 0.42 MBytes requires only 84 millisecond for hardware architecture, and one minute for software architecture, making both designs highly suitable for real-time ultrasonic imaging applications. Furthermore, the 3D compression is implemented by using OpenCL, which is adaptable to various platforms such as CPUs, GPUs and FPGAs. Therefore, OpenCL provides similar computational performance as that of hardware architecture, and the same flexibility as that of software implementation. This study demonstrates that the OpenCL implementation of ultrasonic 3D compression algorithm on Nvidia GT 750M graphical processing unit (GPU) completes the operation in less than one second.
Ph.D. in Electrical and Computer Engineering, May 2015
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Title: SECURITY POLICY MANAGEMENT, THREAT ALLEVIATION AND TRUSTED PLATFORMS FOR EMBEDDED COMPUTING SYSTEMS
Creator: Anand, Vijay
Date: 2011-08, 2011-07
Description: Security guarantees are a measure of trust that can be placed on computing services in the safeguarding of digital assets. These security...
Show moreSecurity guarantees are a measure of trust that can be placed on computing services in the safeguarding of digital assets. These security goals and guarantees coupled with known and modeled threats to the digital assets shape the security policies for computing services. The creation, management and implementation of security policies in computing services is a challenge in defining the role of policy, the management principle for decision making when posed with threats and overall control over digital assets in a well-defined manner. In this Ph.D. thesis we establish a causal relationship of security policies with threats, provide an industry standard management framework (Six Sigma) for decision making, changes to the constructs of the trusted platform module to create a control framework and, finally show how the security framework can be used in a commercial service. The process of updating and refactoring security policy changes becomes a time consuming and tedious task, especially when threats evolve and computing service constructs change when security policy implementations are implicitly implemented. With the basis of correlation of policies over threats an explicit security policy implementation is proposed such that its adaptability, testability and risk quantification can be achieved when threats evolve. In this study we explore policy threat correlation on a Trusted Platform Module (TPM), a hardware system entrusted with security operations and guarantees. An effective TPM needs to adapt to evolving threats arising from firmware bugs or decay in the complexity of ciphering algorithms. Therefore, an adaptive TPM architecture is proposed to counter evolving threats by integrating an FPGA (Field Programmable Gate xi Arrays) block to alter and patch firmware and change ciphering systems. We present how security guarantees in an IT(Information Technology) infrastructure can be met using a TPM and thereby should be an integral part of computing services along with other security constructs like firewalls, intrusion detection systems, anti-virus, etc.. Adaptive security policy requires a management process wherein the risk management, and cost effectiveness principles can be identified. This is essential to make decisions on the trust criteria of digital assets in an industrial management framework. The security policy creation and management process presented in this thesis is based on Six Sigma model and presents a method to adapt security goals and risk management in an industrial framework. As an effective implementation of the security policy the case of application commerce workflow for developers is presented. Secure application distribution and execution guarantees lie in the transfer of trust between various processes in a computing service, also known as Chain of Trust in an embedded system. This study presents application development workflows facilitating secure commerce of digital assets thereby improving consumer trust.
Ph.D. in Computer Engineering, July 2011
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Title: POWER OPTIMIZATION FROM REGISTER TRANSFER LEVEL TO TRANSISTOR LEVEL IN DEEPLY SCALED CMOS TECHNOLOGY
Creator: Li, Li
Date: 2012-04-25, 2012-05
Description: With the progress of CMOS technology, there is a steady growth in clock frequency and chip capacity. As a result, the power dissipation of...
Show moreWith the progress of CMOS technology, there is a steady growth in clock frequency and chip capacity. As a result, the power dissipation of deeply scaled digital CMOS design has increased tremendously. On the other hand, low power VLSI designs are crucial in many areas, such as mobile phones. Furthermore, according the 2011 International Technology Roadmap for Semiconductors (ITRS), the trend towards high power consumption is far beyond the power requirement. As a result, power optimization techniques are highly appreciated in nowadays VLSI design. There are various low power methodologies from system level to layout level. In our research, we are focusing on low power techniques from register transfer level (RTL) to transistor level. Clock gating (CG) is the most widely used technique to reduce dynamic power at RTL. One of the traditional CG styles is XOR-based CG. It compares the inputs and outputs of flip-flops (FFs), and gated the FFs when they are the same. However, this CG is not effective since it does not take the signal activities into account. In this thesis, an activity-driven optimized bus specific clock gating (OBSC) is proposed. It uses finegrained RTL power models to estimate the dynamic power, and chooses only a subset of FFs to be gated selectively based on their switching activities. During the clock gated period, the gated FFs’ outputs are stable. As a result, the combinational logics which are completely dependent on these stable outputs can be power gated so as to save leakage power. Thus, CG and power gating (PG) can be integrated to reduce dynamic and leakage power simultaneously. The sleep signal of our PG is the CG enable signal which is generated during the CG implementation. It does not require an individual power management block to generate as in the case of traditional PG implementation. Moreover, in order to determine if PG leads to leakage power savings, minimum average idle time concept is proposed. Lastly, as a critical part in the integration of CG and PG, data retention logics (DRLs) are required to hold the values of the power gated logics’ outputs so that the non power gated blocks which depend on those outputs can function correctly during the power gated period. In this thesis, a low power DRL design is presented. All the above mentioned techniques have been applied to ISCAS’89 benchmark circuits, and their correctness has been verified successfully. Moreover, the whole experimental process is accomplished automatically by software program, so it is easy to be integrated into current EDA tools.
Ph.D. in Computer Engineering, May 2012
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Title: GALLIUM NITRIDE NANOSTRUCTURED POWER SEMICONDUCTOR DEVICES
Creator: Sabui, Gourab
Date: 2017, 2017-05
Description: Gallium nitride (GaN) has emerged as a promising material for development of power semiconductor devices owing to its superior material...
Show moreGallium nitride (GaN) has emerged as a promising material for development of power semiconductor devices owing to its superior material characteristics. Fabricated GaN power devices have started to outperform its silicon (Si) counterpart with low conduction and switching losses and holds the key to extremely low-loss and high efficiency power delivery circuits of the future. However, GaN power devices have been plagued with several inherent drawbacks preventing an ubiquitous adoption of GaN as the material of choice for power switches. The most critical trade-o↵ has been the choice of substrate for the growth of GaN epitaxy: a high performance, high-cost native substrate or a low-cost, non-native substrate with reliability issues. In order for GaN to thrive as a superior successor to Si, a low cost, high performance epitaxy with improved reliability is expected moving forward. A novel nanostructured approach to GaN power devices is proposed in this dissertation. The nano-GaN power devices theoretically has the potential to bypass the reliability concerns associated with a non-native substrate but still deliver comparable performance. A comprehensive model is proposed for TCAD modeling of bulk GaN power devices to accurately model the nano-GaN devices. Through extensive modeling and simulations, design guidelines for Schottky barrier diodes and field effect transistors based on the nano-GaN concept is laid out to extract the best performance out of this architecture. Dielectric and semiconductor interaction is also exploited to push these devices to perform beyond the unipolar material limit of GaN. The simulated and fabricated nano-GaN power devices show the potential to deliver equivalent or superior performance to present state of the art GaN devices but with improved reliability, ruggedness and low cost.
Ph.D. in Electrical Engineering, May 2017
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Title: AN INTEGRATED RESOURCE MANAGEMENT AND SCHEDULING FRAMEWORK FOR PRODUCTION SUPERCOMPUTERS
Creator: Tang, Wei
Date: 2012-07-16, 2012-07
Description: Resource management and job scheduling is a crucial task on large-scale computing systems. Despite years of research on resource management...
Show moreResource management and job scheduling is a crucial task on large-scale computing systems. Despite years of research on resource management and scheduling, it has not kept pace with modern changes and technology trends. The study of this thesis is motivated by emerging issues observed in current production supercomputers, caused by reasons such as human behaviors, application characteristics, and increasing system complexity. Specifically, users tend to provide inaccurate parameters for their jobs which are dependent by the scheduler; system owners have diverse goals which are always conflicting with each other. Also, workload characteristics on production supercomputers keep changing unpredictably, making it hard to achieve a sustainable scheduling performance since scheduling policies are largely dependent on workload characteristics. Further, increasing hardware complexity causes system issues and leads to new demands. For example, issues such as node fragmentation, failure interruption, power consumption, and I/O overhead have become common in large-scale systems. Existing resource management systems lack the support for these issues and demands. In this study, we present an integrated resource management and scheduling framework, aiming at addressing emerging issues and challenges in resource management for large-scale production supercomputers. We have designed a set of new schemes, including job parameter prediction, adaptive metric-aware job scheduling, cost-aware job scheduling, and multi-domain job coscheduling. We have implemented these approaches in the production resource manager Cobalt, and evaluated them with real job traces from production supercomputers such as the Blue Gene/P system at Argonne National Laboratory. Experimental results show our schemes can effectively improve job scheduling regarding both user satisfaction and system utilization.
Ph.D. in Computer Science, July 2012
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Title: DESIGN AND ANALYSIS OF DATAPATH CIRCUITS USING MULTI-GATE TRANSISTORS
Creator: Garcia Martin, Martin
Date: 2015, 2015-07
Description: Multi-Gate Field-E ect Transistors are transistors with more than one gate that allows continuation of Moore's Law and performance increases...
Show moreMulti-Gate Field-E ect Transistors are transistors with more than one gate that allows continuation of Moore's Law and performance increases for CMOS tran- sistors. Introduction of multi-gate devices has been a turning point for the semi- conductor industry in facilitating transition from planar to 3D structures. Intel rst introduced commercial products using 3D structures (called Tri-Gate transistors) in late 2011 with Ivy Bridge CPUs using 22nm processes. Signi cant performance gains have been reported; i.e., 37% performance increase at low voltage and 50% power reduction. Multi-gate transistors based on 3D structures can vary greatly in their con guration and architectures leading to ambiguity in their design. It is necessary to investigate the performance of datapath circuits when multi-gate and independent- gate devices replace the conventional planar transistors. Therefore, key objective of this work has been to analyze these transistors' performance and to design new dat- apath circuits to leverage the inherent qualities of multi-gate transistor structures. Multiple-gate devices can be modeled using the BSIM-CMG (Common Multi- Gate) and BSIM-IMG (Independent Multi-Gate) compact models from University of Berkeley Device Group. In this research, both device types have been characterized for a variety of parameters to study their basic properties, functionality and to build a foundation for improved circuit designs. In particular, BSIM-CMG devices have been compared with CMOS planar technology demonstrating signi cant advantages in all design metrics, meanwhile the BSIM-IMG have been used to design new gates and improve datapath designs. In the rst part of this study, essential logic gates, i.e. Inverter, NAND and NOR, have been implemented using BSIM-CMG devices. After being analyzed and compared with the CMOS technology, a 32% reduction on dynamic power consump- tion and 82% reduction for the leakage current has been obtained. For a compre-hensive look on full adder designs, several novel adder architectures have been im- plemented including ultra low power and minimum number of transistor (10T) de- signs. The analysis of these implementations shows 54% dynamic power reduction, 98% static current reduction and 26% delay reduction. These results lead to a 68% improvement on the Power-Delay product comparing with the 32nm CMOS planar technology. In order to investigate dynamic logic circuits with multi-gate transistors, two recent dynamic circuit techniques have been implemented with novel enhancements to reduce the leakage current. Data Driven Dynamic Logic (D3L) and Split-Path Data Driven Dynamic Logic (SPD3L) have been used to analyze the dynamic logic circuits resulting in 11% reduced dynamic power, 52% reduced leakage current and 33% reduced delay. Second part of this study deals with the independent gate devices. Using the BSIM-IMG model, new XOR/XNOR logic gate designs are introduced for im- plementing novel low-power adders. With these new adder architectures, the average improvement on Dynamic power is an 8% and the designs are 6% faster. Furthermore, a new design technique is proposed combining the possible modes (Short Gate-SG, Low-Power-LP, Independent Gate-IG) that the BSIM-IMG provides. Using this novel mixed design, the Power-Delay product is improved on average 7.2% and 54%, com- pared to the Short-Gate (SG) and Low-Power (LP) modes, respectively. The properties of the BSIM-IMG logic have been applied to improve the Dy- namic logic designs as well. The Domino and SPD3L design techniques have been implemented and enhancements such as merging the pull-up transistors have been proposed for sleep and power-gating techniques. With these enhancements, the Dy- namic power is reduced 13% in average and the designs are 18% faster. The trade-o is an increase on leakage current of 8%. Another major contribution of the work has been the development of shell script les for generating a custom toolbox for datapath designs with multi-gate and independent-gate transistors.
Ph.D. in Electrical and Computer Engineering, July 2015
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Title: PMU DATA APPLICATIONS IN SMART GRID: LOAD MODELING, EVENT DETECTION AND STATE ESTIMATION
Creator: Ge, Yinyin
Date: 2016, 2016-05
Description: The thesis mainly includes four parts of research, event detection, data archival reduction, load modeling, state estimation. Firstly, we...
Show moreThe thesis mainly includes four parts of research, event detection, data archival reduction, load modeling, state estimation. Firstly, we present methods on real-time event detection and data archival reduction based on synchrophasor data produced by phasor measurement unit (PMU). Event detection is performed with Principal Component Analysis (PCA) and a second order difference method with a hierarchical framework for the event notification strategy on a small-scale Microgrid. Compared with the existing methods, the proposed method is more practical and efficient in the combined use of event detection and data archival reduction. Secondly, the proposed method on data reduction, which is an “Event oriented auto-adjustable sliding window method”, implements a curve fitting algorithm with a weighted exponential function-based variable sliding window accommodating different event types. It works efficiently with minimal loss in data information especially around detected events. The performance of the proposed method is shown on actual PMU data from the IIT campus Microgrid, thus successfully improving the situational awareness (SA) of the campus power system network. Thirdly, we present a new “event-oriented” method of online load modeling for the IIT Microgrid based on synchrophasor data produced PMU. Several load models and their parameter estimation methods are proposed. It is given great importance on choosing the best models for the detected events. The online load modeling process is based on an adjustable sliding window applied to two different types of load step changes. The load modeling tests and related analysis on the synchrophasor data of the IIT Microgrid are demonstrated in this paper. Finally, we present a three-phase unbalanced distribution system state estimation (DSSE) method based on Semidefinitetheir parameter estimation methods are proposed. It is given great importance on choosing the best models for the detected events. The online load modeling process is based on an adjustable sliding window applied to two different types of load step changes. The load modeling tests and related analysis on the synchrophasor data of the IIT Microgrid are demonstrated in this paper. Finally, we present a three-phase unbalanced distribution system state estimation (DSSE) method based on Semidefinite Programming (SDP). A partitioning strategy with the aid of PMU and another distributed optimization algorithm alternating direction method of multipliers (ADMM) are also proposed for large-scale DSSE. Compared with a traditional weighted least square (WLS) method based on the Gauss-Newton iteration, the proposed DSSE by SDP method delivers a more accurate estimation, and the application of ADMM can lead to high performance for large scale DSSE while deriving satisfying estimation.
Ph.D. in Electrical Engineering, May 2016
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Title: COORDINATION OF STORAGE WITH RENEWABLE ENERGY RESOURCES IN POWER SYSTEMS
Creator: Khodayar, Mohammad Esmaeil
Date: 2012-07-16, 2012-07
Description: The ever-increasing penetration of variable wind energy in power systems affects the hourly dispatch of thermal power generation in...
Show moreThe ever-increasing penetration of variable wind energy in power systems affects the hourly dispatch of thermal power generation in electricity markets. The coordination of wind power generation units with pumped-storage hydro (PS) generation could relieve the variability of wind energy and increase its hourly dispatchability. In this dissertation, a coordination methodology for wind and pumped-storage hydro (PS) units in the dayahead operation planning of power systems is proposed. With coordination, the PS unit can offset intrahour wind energy imbalances (i.e., deviations from hourly schedules) and minimize wind energy curtailments. The wind-PS coordination based on the application of stochastic security-constrained unit commitment (Stochastic SCUC) is evaluated in which, the hourly bus- level coordinated scheduling of wind energy and PS is compared with the system-level coordinated operation strategies in the day-ahead scheduling of power systems. Volatility of wind generation can also reduce the profit in day-ahead market by imposing potential imbalance charges in a generating company (GENCO). The dayahead price-based scheduling strategy for the coordination of wind and storage units in a GENCO is proposed based on the stochastic price-based unit commitment (PBUC) which considers volatilities in day-ahead intra-hour market prices and wind power generation when scheduling wind and storage units. The increased utilization of Plugin Electric Vehicles (PEVs), which consume electricity rather than fossil fuel for driving, offers unique economic and environmental opportunities, and brings out new challenges to electric power system operation and planning. The proposed approach evaluates the effect of integrating a large number of electric vehicles (EVs) on power grid operation and control. The coordinated integration of aggregated PEV fleets and renewable energy sources (wind energy) in power systems is studied by stochastic security-constrained unit commitment (Stochastic SCUC) model, which minimizes the expected grid operation cost while considering the random behavior of the many PEVs. Finally, the role of high reliability distribution system (HRDS) in microgrid operations is evaluated. HRDS, which offers a higher operation reliability and fewer outages in microgrids, is applied to looped networks in distribution systems. The storage system would enhance the microgrid reliability while offering hourly ancillary services and demand response for reducing operation costs. The HRDS implemented at Illinois Institute of Technology (IIT) is used as a case study along with the local DER to increase the load point reliability and decrease the operation cost of the microgrid.
Ph.D. in Electrical Engineering, July 2012
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Title: IMPLICITLY-COUPLED ELECTROMECHANICAL AND ELECTROMAGNETIC TRANSIENT ANALYSIS
Creator: Zhang, Xu
Date: 2015, 2015-05
Description: The operation of an electrical power system involves continuous electromechanical and electromagnetic interaction of energy among the system...
Show moreThe operation of an electrical power system involves continuous electromechanical and electromagnetic interaction of energy among the system components. Under normal operation, the system behavior could be represented by voltage and current phasors in the frequency domain. However, the system may not work on the fundamental frequency following some fast transients (loss of generator, switching event, system disturbance and etc.), at this time we need specific tools to investigate the dynamic scenario. Transient stability (TS) simulator, also referred to as electromechanical transient simulator, running at time steps on the order of milliseconds and only capable of capturing the fundamental frequency transient, is used for the analysis of largescale networks. On the other hand the electromagnetic transient (EMT) simulator running at time steps on the order of microseconds, with detailed equipment modeling is capable of analyzing transients over a wider frequency spectrum; however, it is computationally onerous, so it is typically restricted to the analysis of small networks. An electromechanical-electromagnetic transient simulator is the combination of a TS simulator and an EMT simulator, inheriting the merits of both programs. The basic idea of an electromechanical-electromagnetic simulator is to decompose the power system into two broad categories: a large connected TS network (main network) and smaller EMT network (detailed subsystem). The main network is running on TS simulator while the detailed subsystem is running on the EMT simulator. The implicitly-coupled electromechanical and electromagnetic simulator has TS and EMT simulators coupled at the equation solution level, which could ensure the consistence of the solution between TS and EMT simulation. Instead of using fundamental frequency equivalent model of the main network in EMT simulation of implicitly-coupled electromechanical and electromagnetic simulator, a frequency dependent network equivalent (FDNE) model is utilized to preserve the non-fundamental frequency fast transient response of the main network. Along with the implementation of FDNE model, this research work also propose a new TS simulator that is capable of running three-phase transient stability simulation under fundamental and non-fundamental frequency simultaneously. Furthermore the performance of implicitly-coupled electromechanical-electromagnetic transient simulator could be improved with the implementation of this new TS simulator.
Ph.D. in Electrical and Computer Engineering, May 2015
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Title: SUPERVISED AND INTERACTIVE IMAGE SEGMENTATION TECHNIQUES WITH AN APPLICATION TO PROSTATE CANCER
Creator: Artan, Yusuf Oguzhan
Date: 2013, 2013-05
Description: Prostate cancer is a leading cause of cancer death for men in the United States. Fortunately, the survival rate for early diagnosed patients...
Show moreProstate cancer is a leading cause of cancer death for men in the United States. Fortunately, the survival rate for early diagnosed patients is relatively high. Accurate prostate cancer localization with noninvasive imaging using MRI can be used to guide biopsy, radiotherapy, and surgery as well as to monitor disease progression. However, in general, a single type of MRI is not sufficient for reliable tumor localization. As an alternative, multispectral MRI, i.e., the use of multiple MRI-derived datasets, has emerged as a promising noninvasive imaging technique for the localization of prostate cancer; however almost all studies are with human readers. There is a significant inter and intra-observer variability for human readers, and it is substantially difficult for humans to analyze the large dataset of multispectral MRI. To solve these problems, this thesis presents various novel supervised and semi- supervised (interactive) segmentation techniques. Initially, we develop a supervised segmentation method by combining conditional random fields (CRF) and support vector machines (SVM) with a cost-sensitive framework, and show that proposed method further improves classical and cost-sensitive SVM results by incorporating spatial information. Next, we propose an extension of popular semi-supervised seg- mentation method, namely random walker (RW) algorithm, with automated seed initialization for multispectral MRI images. We also present an automated shape and boundary based segmentation approach for prostate segmentation from T2-weighted MRI. Proposed method is based on a banded geocuts algorithm that utilizes bound- ary and shape information to yield prostate segmentation. Finally, we develop a novel method that has the ability to design classifiers obtained from one imaging protocol and/or MRI device to be used on a dataset from another protocol and/or imaging device. In order to evaluate the performance of the proposed methods, we utilize multispectral MRI datasets acquired from 21 biopsy-confirmed cancer patients. Our results show that multispectral MRI helps to increase the accuracy of prostate cancer xiv localization when compared to single MR images; and that using advanced proposed methods for prostate cancer localization performs better than available methods in the literature.
PH.D in Electrical Engineering, May 2013
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Title: MICROGRIDS AND DISTRIBUTED GENERATION SYSTEMS: CONTROL, OPERATION,COORDINATION AND PLANNING
Creator: Che, Liang
Date: 2015, 2015-07
Description: Distributed Energy Resources (DERs) which include distributed generations (DGs), distributed energy storage systems, and adjustable loads are...
Show moreDistributed Energy Resources (DERs) which include distributed generations (DGs), distributed energy storage systems, and adjustable loads are key components in microgrid operations. A microgrid is a small electric power system integrated with onsite DERs to serve all or some portion of the local loads and connected to the utility grid through the point of common coupling (PCC). Microgrids can operate in both gridconnected mode and island mode. The structure and components of hierarchical control for a microgrid at Illinois Institute of Technology (IIT) are discussed and analyzed. Case studies would address the reliable and economic operation of IIT microgrid. The simulation results of IIT microgrid operation demonstrate that the hierarchical control and the coordination strategy of distributed energy resources (DERs) is an effective way of optimizing the economic operation and the reliability of microgrids. The benefits and challenges of DC microgrids are addressed with a DC model for the IIT microgrid. We presented the hierarchical control strategy including the primary, secondary, and tertiary controls for economic operation and the resilience of a DC microgrid. The simulation results verify that the proposed coordinated strategy is an effective way of ensuring the resilient response of DC microgrids to emergencies and optimizing their economic operation at steady state. The concept and prototype of a community (networked) microgrid that interconnecting multiple microgrids in a community are proposed. Two works are conducted. For the coordination, novel three-level hierarchical coordination strategy to coordinate the optimal power exchanges among neighboring microgrids is proposed. For the planning, a multi-microgrid interconnection planning framework using probabilistic minimal cut-set (MCS) based iterative methodology is proposed for enhancing the economic, resilience, and reliability signals in multi-microgrid operations. The implementation of high-reliability microgrids requires proper protection schemes that effectively function in both grid-connected and island modes. This chapter presents a communication-assisted four-level hierarchical protection strategy for highreliability microgrids, and tests the proposed protection strategy based on a loop structured microgrid. The simulation results demonstrate the proposed strategy to be an effective and efficient option for microgrid protection. Additionally, microgrid topology ought to be optimally planned. To address the microgrid topology planning, a graph-partitioning and integer-programming integrated methodology is proposed. This work is not included in the dissertation. Interested readers can refer to our related publication.
Ph.D. in Electrical and Computer Engineering, July 2015
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Title: PHOTOCONDUCTIVE SWITCH IMPLEMENTED WITH GALLIUM ARSENIDE ON SILICON NITRIDE FOR COPLANAR WAVEGUIDE BASED TERAHERTZ SPECTROMETER
Creator: Fu, Xiaohuan
Date: 2015, 2015-12
Description: Over the years, pulsed terahertz (THz) time domain spectroscopy has attracted a lot of interest since it can not only measure the intensity of...
Show moreOver the years, pulsed terahertz (THz) time domain spectroscopy has attracted a lot of interest since it can not only measure the intensity of the transient electric eld but also determine the amplitude and phase of the spectral components that make up the pulse. This provides a convenient method to obtain the molecular network information of chemical or biological samples. Signi cant e orts have been directed towards free space spectroscopy in which THz pulses travel in free space between photoconductive transceivers. Due to di raction limit, the resolution is insu cient for many applications and it results in extreme power requirements or low power densities of the probe pulse. To overcome this issue, we propose a planar THz spectrometer which uses the same photoconductive excitation and detection mechanism as free space spectroscopy, but the excited THz pulses are directly coupled into lithographically de ned coplanar transmission lines. To reduce the power loss in the substrate, a thin lm with lower permittivity is employed to replace the conventional silicon substrate at the location where the coplanar waveguide is fabricated. To obtain high sensitivity, sample can be directly placed on the coplanar waveguide for tight coupling of the eld. Conceptual design and EM simulations have been completed and a variety of experimental studies have been carried out at Argonne National Laboratory to understand the fundamentals of coplanar waveguide. The fabrication of the coplanar waveguide prototype have been conducted at Northern Illinois University. The challenge of building a photoconductive switch with LTG-GaAs on Si3N4 was encountered and an innovative wafer bonding technique was discovered. Several wafer treatments prior to and after wafer bonding have been demonstrated to improve the bonding strength and reduce the defects. A standard pump-probe optics setup has been built at DePaul University and the photoconductive switch have been tested with femtosecond laser. The results con rmed that the photoconductive switches are functioning as design and the device system is ready for THz spectroscopy application. The historical overview of THz spectroscopy research and fundamentals of coplanar waveguide and photoconductive switches are presented in Chapter 1-3, followed by EM simulation, conceptual design in Chapter 4. The details of microfabrication process and the testing results are discussed in Chapter 5 and 6. The project is summarized in Chapter 7.
Ph.D. in Electrical Engineering, December 2015
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Title: NEW BEAMFORMING AND SPACE-TIME CODING SCHEMES FOR MIMO WIRELESS SYSTEMS
Creator: Tavassoli, Farhad
Date: 2013, 2013-05
Description: Space-time coding and Beamforming are two main techniques utilized in multiple-input multiple-output (MIMO) wireless systems to increase...
Show moreSpace-time coding and Beamforming are two main techniques utilized in multiple-input multiple-output (MIMO) wireless systems to increase channel capacity. In this work, we present new beamforming algorithms and space-time codes for MIMO wireless systems to reduce the complexity and enhance the performance. We present a new framework to obtain beamforming algorithms for code division multiple access (CDMA) and orthogonal frequency division multiplexing (OFDM) systems based on principal component analysis (PCA) approach. Four different PCA objective functions are used as examples to illustrate how to obtain new beamforming algorithms based on the proposed framework. Since two of the objective functions result in the same algorithm, three different beamforming algorithms are obtained for CDMA and OFDM systems. We show that the new algorithms offer a desirable performance while they have considerably lower computational complexity than the optimum algorithms. It is demonstrated that the proposed algorithms also have a fast convergence rate. We also propose new space-time codes for both coherent and non-coherent wireless systems which can provide lower symbol error rates than existing codes in the same class. For the coherent case, we propose a new quasi-orthogonal code to provide a full-rate full-diversity transmission. Unlike the other codes in the literature, the proposed code does not require the transmitted symbols to be chosen from two different constellations. Choosing all symbols from only one constellation reduces the required storage memory to half of that needed in other methods. It also avoids decreasing the minimum distance between the symbols and hence, avoids degrading the coding gain. For the non-coherent case, a new constellation design for differential unitary space-time modulation is proposed. We generate xi a set of unitary matrices from the multiplication of a simple unitary matrix with entries of 1 by diagonal matrices made from quaternary alphabets. Then, the proposed constellation is formed from the product of the optimum matrix chosen from this set and the optimized diagonal matrix first used for the cyclic codes. We show that the proposed constellation yields a larger diversity product as well as a lower union bound for pairwise error probability with the same or lower complexity compared to other existing constellations.
PH.D in Electrical Engineering, May 2013
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