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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: LICENSE PLATE RECOGNITION SYSTEM USING K NEAREST NEIGHBOR ALGORITHM
Creator: Xia, Yong
Date: 2012-12-03, 2012-12
Description: License Plate Recognition (LPR) is an image-processing technology, also known as Automatic Number Plate Recognition (ANPR). This technology is...
Show moreLicense Plate Recognition (LPR) is an image-processing technology, also known as Automatic Number Plate Recognition (ANPR). This technology is very popular in fighting crime, locating stolen car, identifying parking-ticket and so on. In LPR system, the image is taken of the front or rear of the car and its quality needs to be enhanced for further process. With this enhanced image, first license plate region is located and extracted. Then character segmentation is performed on extracted license plate image. In this thesis, we use K Nearest Neighbor (KNN) algorithm to recognize these segmented characters. Keywords: LPR, Plate location, character segmentation, Image Processing, KNN
M.S.in Electrical 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: ANTENNA LOCATION DESIGN IN DOWNLINK DISTRIBUTED ANTENNA SYSTEM
Creator: Zhang, Peng
Date: 2015, 2015-07
Description: In recent years, Wireless cellular network design with distributed antenna system (DAS) has received much attention for its ability to extend...
Show moreIn recent years, Wireless cellular network design with distributed antenna system (DAS) has received much attention for its ability to extend the cell coverage, improve spectral efficiency and increase the system capacity. Instead of locating all antennas at the cell center in the centralized antenna systems (CAS), distributed antenna basements in the DAS are separated geographically, which has been wide implemented to cover the dead spots and improve the system efficiency in wireless communication systems The mainly purpose of this research is to find optimal antenna locations that maximize the cell average ergodic capacity for the distributed-antenna system in downlink applied condition. Squared distance criterion (SDC) will be considered to offer an object function to maximize the lower bound of the cell average ergodic capacity. Existed analyses for location design in distributed antenna system are based on the uniform distribution without considering other cell interference. Considering other cell interference, I derive the analytical antenna location position for the infinite uniform distribution linear cell. For multi-cell applied condition implementation, I get reasonable locations of the applied condition by applying K-means algorithm to generating the initial values and find the optimal location. In order to solve the multi-cell scenario considering other-cell interference, I change the existed algorithm and simulation results show the performance of the obtained antenna location with changed algorithm offer a higher performance than the original one. I propose a circle initial setup to generate the initial points for relative location and converge fitting. The simulation has showed the initial setup I proposed significant reduce the computation in the antenna location design in applied downlink scenario.
M.S. in Electrical Engineering, July 2015
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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: AN ANALYTICAL MODEL FOR SWITCHED RELUCTANCE MACHINE WITH HIGHER NUMBER OF ROTOR POLES
Creator: Jia, Yijiang
Date: 2012-05-08, 2012-05
Description: With growing interest in renewable energy technology and hybrid electric vehi- cle systems owing to environmental concerns and depleting...
Show moreWith growing interest in renewable energy technology and hybrid electric vehi- cle systems owing to environmental concerns and depleting fossil fuel reserves, electric machines have received widespread attention as a key component in the successful im- plementation of high efficiency drives. Towards this goal, the last two years have seen a significant increase in research in permanent magnet-alternative machine topologies. This has primarily been because of growing concerns over foreign dependence for rare- earth materials and a dramatic increase in the cost of permanent magnets. Switched Reluctance Machine (SRM) has been one of the leading contenders in this category. It does not require any permanent magnets, and is very suitable for operation in harsh operating environments. Furthermore, this machine has simple construction and is highly fault-tolerant with one of the widest operating speed ranges. Nowadays, it has found wide application in the automotive, aerospace as well as domestic area. How- ever conventional SRM suffers from modeling complexity and torque ripple during the phase commutation with the same origin. Using the novel PD formula proposed at the Illinois Institute of Technology, a new family of machines has been developed with a significant improvement in torque ripple. Owing to its novel configuration, analytical models for the design of advanced driver system design have also not been developed. In this study, an analytical model for the novel 6/10 SRM has been proposed. The machine model is characterized using an inductance model utilizing truncated Fourier series as well as multi-order polynomial curve-fitting algorithm. The induc- tance model is extended to back-EMF and electromagnetic torque models on purpose of obtaining the whole information for every single operating point of the machine during dynamic operation. The effectiveness of the proposed concept has analyzed for a prototype machine in the laboratory and verified using Finite Element Analysis. From this study, an algorithm has been proposed to develop the analytical model for the family of SRMs with higher number of rotor poles.
M.S. in Electrical Engineering, May 2012
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Title: ANALYSIS AND PROTOTYPING OF ENERGY HARVESTING SYSTEM BASED ON DIELECTRIC ELECTRO ACTIVE POLYMER
Creator: He, Peiwen
Date: 2012-04-26, 2012-05
Description: Energy harvesting is a new emerging technology which is used to gather am- bient energy from all surroundings. Dielectric Electro Active...
Show moreEnergy harvesting is a new emerging technology which is used to gather am- bient energy from all surroundings. Dielectric Electro Active Polymer (DEAP) is a new material for energy harvesting based on mechanical-to-electric energy conversion. By using MATLAB simulation, a new system design based on DEAP is proposed to harvest energy. In the proposed system, the energy harvesting and the feedback cir- cuit loops can keep the system working without an external source. The simulation results show that the proposed system can harvest energy, and the bias voltage can be supplied by the system itself. Hence, no external source is needed. For circuit level design, based on two different vibration input patterns in terms of mechanical vibration frequency and displacement, two topologies of system forward paths which include DEAP generator, voltage regulation circuit and DC-DC buck converter are designed. For the low frequency high displacement vibration input pattern, a low frequency forward path is developed by using Zener diode regulator. For the high frequency low displacement input pattern, a high frequency forward path is designed by using Butterworth low pass filter. PSPICE simulation results prove that both of the proposed circuits work properly to generate steady DC voltage for energy harvesting. Finally, a prototyping circuit including a low pass filter and a battery charging module is implemented in experiment to verify the feasibility of partial system func- tion. The results show that the prototyping circuit for the proposed energy harvesting system by using DEAP can work well.
M.S. in Electrical Engineering, May 2012
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Title: A 2-GHZ FREQUENCY MULTIPLIER BASED ON DIGITAL DELAY LOCK LOOP IN 65 NM CMOS
Creator: Zhang, Kaiqiang
Date: 2017, 2017-05
Description: Generally phase lock loops (PLLs) are utilized in the implementation of the conventional clock generators and frequency multipliers. However...
Show moreGenerally phase lock loops (PLLs) are utilized in the implementation of the conventional clock generators and frequency multipliers. However there are some issues happened during designing PLLs. First of all, PLLs has a stability issue due to its higherorder systems. And this issue will cause the change of the loop bandwidth when PVT is different. Secondly, in PLLs, the output of the VCO will be fed back to the loop, which causes a peak phase error unexpectedly larger than the desired phase variation since jitter is accumulating over the oscillation cycles. These issues will make the design of a PLLbased frequency multiplier more complicated and challenging. In order to solve these issues, this thesis presents a 2-GHz frequency multiplier based on digital delay lock loop. In this design when the DLL is locked the digital DLL operated in the open-loop mode will reduce the jitter and power consumption due to dithering in the lock condition. In this design a compensation structure is proposed to keep track of any potential phase error caused by environmental variations. The reference input frequency is 500M Hz. This frequency multiplier is designed and fabricated in a 65nm CMOS. The thesis also provides theory and simulation results on frequency multiplier for readers.
M.S. in Electrical Engineering, May 2017
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Title: A DEVICE-TO-DEVICE COMMUNICATION AND KEY EXCHANGE APPLICATION OVER WI-FI DIRECT
Creator: Hong, Weisheng
Date: 2014, 2014-12
Description: With the rapid growth of smartphone and tablet users, Device-to-Device (D2D) communications have become an attractive solution for enhancing...
Show moreWith the rapid growth of smartphone and tablet users, Device-to-Device (D2D) communications have become an attractive solution for enhancing the performance of traditional cellular networks. However, relevant security issues involved in D2D communications have not been addressed yet. In this thesis, I investigate the security requirements and challenges for D2D communications, and present a secure and efficient key agreement protocol, which enables two mobile devices to establish a share secret key for D2D without prior knowledge. The mobile devices are playing an important role in our social life. People trend to share their files and chat with each other without Wi-Fi. Wi-Fi Direct technology provides a very good way to satisfy people’s need. After established a security D2D communication, I used the socket communication method to implement the chat function between devices and some protocols to enable the files transmitted. In the file transfer function, my demo support any types of the files. In the chat function, my demo also uses the shared secret to encrypt the message and then the receiver can decrypt it with the shared secret.
M.S. in Electrical Engineering, December 2014
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Title: STUDY ON EX POST PRICING
Creator: Zhao, Zhechong
Date: 2011-05-02, 2011-05
Description: The main objective of this thesis is to study the ex post pricing in electricity market by implementing two new methods (quantity based method...
Show moreThe main objective of this thesis is to study the ex post pricing in electricity market by implementing two new methods (quantity based method and price based method). The quantity based method measures the difference between the actual performance of an individual resource and its bid-based profit-maximizing response to the ex post prices. The price based method measures the different between the ex post price and the supporting price which supports the actual outputs. These two methods are based on a co-optimization market for energy and ancillary service. They are very flexible and can solve the ex post price efficiently and simultaneously.
M.S. in Electrical Engineering, May 2011
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Title: DETECTING A SPIT CALLER USING UN-SUPERVISED MACHINE LEARNING
Creator: Opara, Stanley
Date: 2013-05-02, 2013-05
Description: Spam over Internet Telephony (SPIT) is a form of un-solicited communication whereby an attacker sends automatically pre-recorded phone calls...
Show moreSpam over Internet Telephony (SPIT) is a form of un-solicited communication whereby an attacker sends automatically pre-recorded phone calls to several subscribers for purposes such as advertisements of product and services etc. In the near future, SPIT is expected to become a threat inhibiting the delivery of voice services over INTERNET because of its technical and economic characteristics. In this report, we purpose a detection mechanism to identify SPIT callers. This mechanism transforms the problem of identification of SPIT callers to a data clustering one by mapping callers to data points based on some characteristics. These characteristics (features) are gathered based on signaling characteristics, caller reputation and call metrics. These features include modified SymRank, termination coefficient, strong tie coefficient and average call duration. These features distinguish between a normal caller and SPIT caller but cannot stand alone as shown in the Results section. The data clustering was done by an un-supervised learning algorithm known as k-means which clusters closely related data points. To test our model, we simulated a testbed since we could not obtain real traffic. The testbed was generated in java, while the actual clustering algorithms were written Octave. The results gathered clearly showcased the high efficacy of our model, as it had accuracy (>95%) in all tests. After comparing our model with other models proposed by fellow researchers, we realized that our model either surpassed or was comparable to the other models considered.
M.S. in Electrical Engineering, May 2013
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Title: MODELING AND SIMULATION OF DYNAMIC VOLTAGE CONTROLS AND PROTECTION IN 3 PHASES TRANSIENT STABILITY ANALYSIS
Creator: Zhang, Qiaoyu
Date: 2016, 2016-12
Description: The main object of this research is to build up a comprehensive 3-phases transient stability simulator(TS3ph) and use it to analyze the...
Show moreThe main object of this research is to build up a comprehensive 3-phases transient stability simulator(TS3ph) and use it to analyze the transient stability with dynamic voltage control and protection. Detailed exciter models, SVC model and protection model are needed in this research. We have implemented detailed exciter model. We chose several exciter models which are frequently used in power system to built. These exciters can control generator terminal voltage by changing current and voltage to generator field winding. It is critical for improving the dynamic voltage performance in power system. We also built up detailed SVC model. The SVC is an important device for dynamic voltage control. It is a power electronics-based equipment containing both reactors and capacitor banks which have the capability of dynamic voltage and reactive power control. When doing the dynamic voltage control simulation, it is meaningful to have a detailed SVC model in the transient simulator. The another mission of this research is to study the protection of power system with unbalance fault or unbalance network using 3-Phase Transient Stability Simulator. In order to obtain the relay operation, we need to set up the interface between protection simulator Electrocon CAPE and transient simulator TS3ph. As unbalance fault sometimes can cause serious voltage problem during the transient, simulating the unbalance fault with realistic relay operation is important for transient stability analysis.
M.S. in Electrical Engineering, December 2016
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Title: INJECTION LOCKING BASED ULTRA LOW POWER RADIO FREQUENCY INTEGRATED CIRCUITS
Creator: Zhu, Qiang
Date: 2012-05-31, 2012-07
Description: Recent advances in radio frequency integrated circuit (RFIC) technology enable various innovative and versatile applications through ultra-low...
Show moreRecent advances in radio frequency integrated circuit (RFIC) technology enable various innovative and versatile applications through ultra-low-power wireless link such as mesh sensor network, personal area network (PAN) and semi-active RFID. This thesis introduces energy efficient demodulator and transceiver design for wireless communications. At the receiver front end, an ultra-low-power BPSK demodulator based on injection locked oscillators (ILOs) is introduced. Two second harmonic ILOs are employed to convert BPSK signals to ASK signals, which are then demodulated by an envelope detector to baseband. For sub-GHz applications, the ILOs are implemented using ring oscillators to allow compact chip area and ultra-low power dissipation. Bit error rate (BER) analysis of this demodulator indicates erroneous polarity flipping of demodulated bits due to phase noise of the ILO. The prototype chip is fabricated in a 65nm CMOS technology that consumes 228μW of power and occupies 0.014mm2 of die area. Measurement results reveal the demodulation of 750MHz 5Mb/s differential BPSK signal with a sensitivity of -43dBm. Theoretical BER analysis has been verified with erroneous flipping observed in the measurement and its probability close to the prediction. Then, an innovative injecting locking based transceiver architecture for ultra low power operation is proposed. It applied the ILO based BPSK demodulator at the receiver side. The oscillating signal at one receiver ILO also injects to another transmitter ILO for accurate carrier generation. Thus local frequency synthesis circuit which consumes considerable portion of power in traditional transceiver is not required. This design is implemented in a 45nm CMOS SOI technology. Measurement results indicate that the transceiver achieves downlink demodulation of -35dBm BPSK signal at 5Mb/s data rate and uplink transmission of -23dBm ASK signal at 1Mb/s data rate with 0.93mA current consumption from 1V power supply.
Ph.D. in Electrical Engineering, July 2012
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Title: VIDEO FEATURE DETECTION AND MATCHING FOR STRUCTURE FROM MOTION SYSTEM
Creator: Yang, Guojun
Date: 2015, 2015-05
Description: With the improvements in sensor technologies and image processing algorithms, computer vision has become a major tool for robots to recognize...
Show moreWith the improvements in sensor technologies and image processing algorithms, computer vision has become a major tool for robots to recognize and gauge their surroundings. For instance, the Kinect sensor can be used as an excellent depth camera for indoor navigation. However, there exist situations that need recognition and spatial interpretation of the environment using limited hardware resources. The Kinect is not suitable for outdoor use, while LIDAR is too large and expensive to be installed on an autonomous miniature surveillance drone. Therefore, the use of a single camera is the only feasible option for many embedded applications. To perform SfM (structure from motion) by using single camera is challenging due to the complexity of 3D mapping. Feature detection and mapping is the very fist step to perform SfM. To be more specific, matched feature points are used as anchors cross images or frames. Without such matched feature points, most SfM method will not be able to generate reliable results; moreover, instead of using frames from videos as inputs, most feature detectors and matching strategies are designed for SfM applications using images as inputs. Therefore, this thesis will discuss how to detect feature points from video and match them effectively. Image projection and SfM fundamentals will be introduced in this thesis as well.
M.S. in Electrical Engineering, May 2015
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Title: INCORPORATING REACTIVE POWER MARKET INTO THE DAY-AHEAD ELECTRICITY MARKET
Creator: Al Ghamdi, Mohammed
Date: 2012-05-29, 2012-07
Description: The research work presented in this thesis proposes the incorporation of the reactive power market into the day-ahead electricity market in...
Show moreThe research work presented in this thesis proposes the incorporation of the reactive power market into the day-ahead electricity market in order to compensate generation companies (GENCOs) and independent power producers (IPPs) for providing any additional reactive power support, which varies on an hourly basis based on the load demand, transmission network configuration, and any contingencies that might occur. This proposal would minimize the total payment burden on the independent system operator (ISO), which is related to the reactive power dispatch. The proposed model achieves the main objective of an ISO in a competitive electricity market, which is to provide the required reactive power support from generators at minimum cost while ensuring the secure operation of the power system. In this research, the reactive power price is the bidding-based price that is submitted by the GENCOs and IPPs to the ISOs during the day-ahead market. The proposal takes into the account both the technical and economic aspects associated with the active power and reactive power dispatch in the context of the new operating paradigms in competitive electricity markets. In this research, the Security Constrained Unit Commitment (SCUC) based on AC power flow modeling is considered as the drive engine for clearing the day-ahead electricity market based on the amount of information provided by the market participants. This proposed framework would provide appropriate reactive power support from service providers at minimum cost, while ensuring the secure and reliable operation of the electrical power system. In the research, the PQ capability curves of the generating units are modeled to ensure the practically of the SCUC solutions that are obtained. This proposal would be an essential step toward a fair electricity market while increasing the security of the power system and reducing transmission congestions. Also, it would pave the road for various renewable energy resources since the penetration of renewable energy resources would impact the commitment of the generating units. This would impact the available reactive power reserve margin and security of the network. In addition, incorporating the reactive power market into the day-ahead market would provide a clear signal for optimal private investment in the reactive power capacity. The framework that has been developed is general in nature and can be used for any electricity market structure.
Ph.D. in Electrical Engineering, July 2012
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Title: EXPLOITING NETWORK CODING IN DIFFERENT WIRELESS NETWORKS
Creator: Guo, Bin
Date: 2012-07-06, 2012-07
Description: Wireless communication networks have been incorporated into our daily life and provide convenience anytime and anywhere. However, the wireless...
Show moreWireless communication networks have been incorporated into our daily life and provide convenience anytime and anywhere. However, the wireless medium is unreliable and unpredictable. Current wireless networks suffer from low throughput, low reliability, etc. Network coding, an alternative approach, has attracted more interests and has emerged as an important technology in wireless networks. It can provide significant potential throughput improvements and a high degree of robustness. This dissertation is built on the theory of network coding. In this dissertation, different network coding protocols are designed in varied wireless networks. The first part of this dissertation proposes a novel coding-ware routing protocol in wireless mesh networks. In particular, a generalized coding condition is formally established to identify the coding opportunities. Based on general coding conditions analysis, a novel routing metric FORM (Free-ride Optimal Routing Metric) and the corresponding routing protocol are developed with the objective to exploit the coding opportunities and maximize the benefit of “free-ride” in order to reduce the total number of transmissions and consequently to increase the network throughput. The results show the proposed protocol achieves significant throughput gain than existing approaches. The second part of this dissertation exploits network coding in wireless cooperative networks. Firstly, a Decode-and-Forward Network Coded (DFNC) protocol is proposed for multi-user cooperative communication system. In particular, DFNC develops an efficient construction method for coding coefficients and a novel decoding algorithm that combines network coding and channel coding. DFNC exploits both temporal and spatial diversities through multiple channels by allowing all the users to generate redundant network-coded packets in a distributed manner and it helps fully explore the redundancy provided by network coding to realize error correction. Theoretical analysis and simulation results demonstrate that DFNC outperforms other transmission schemes in terms of Symbol Error Rate (SER) and achieves higher diversity order. Secondly, the idea of DFNC is extended and Modified-DFNC (M-DFNC) is introduced for a more practical scenario: not all the users will be able to dedicate their resources to provide assistance for others. The throughput analysis shows that M-DFNC outperforms the conventional cooperative protocol in the low-SNR regime and it implies that an adaptive cooperation system should be adopted to optimize the performance. The simulation results validate the theoretical analysis.
Ph.D. in Electrical Engineering, July 2012
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Title: ULTRALOW POWER SRAM DESIGN IN NEAR THRESHOLD REGION USING 45NM CMOS TECHNOLOGY
Creator: Chen, Yinhui
Date: 2011-05-10, 2011-05
Description: With the development of CMOS technology, the performance including power dissipation and operation speed is highly concerned for SRAM design....
Show moreWith the development of CMOS technology, the performance including power dissipation and operation speed is highly concerned for SRAM design. Desirable low power consumption while operating fast is the goal of design and improvement. However, the tradeoff between performance and speed is one of the most challenging obstacles that engineers are facing. Along with continuously scaling in the process technology, the concern for stability of Static Random Access Memories (SRAMs) is increasing in the design and test. Maintaining an acceptable Static Noise Margin (SNM) as well as scaling the minimum feature sizes and supply voltages of the Systems-on-a-Chip (SoC) becomes more and more challenging. Subthreshold leakage, dynamic power consumption and delay are major issues for circuits design, especially for SRAM design. Subthreshold leakage and dynamic power consumption can be decreased while supply voltage is scaled down. However, this may dramatically increase the circuit delay (Lindert, 1999) (Wang, 2004) (Zhai, 2004). In this dissertation, we first prepared fundamental knowledge of the CMOS technology as well as SRAM. According to the current researches on SRAM (Chang, 2005) (Chen, 2010), we proposed a novel 6t SRAM design which operates in near threshold region to optimize leakage power and speed. Negative word line is introduced to reduce the leakage current. A novel Latch-type voltage sense amplifier is proposed to improve the read speed of the proposed SRAM cell. The proposed SRAM design is implemented in 45nm technology and achieves more than 50% for power reduction, 68% for leakage reduction, 90% for write delay reduction and 78% for read delay reduction compared to traditional 6T SRAM in near threshold region. Although the proposed 6T SRAM inherit the disadvantage of 4T schematic in data retention, the operation stability is still respectable.
M.S. in Electrical Engineering, May 2011
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Title: DEVELOPMENT OF AN IMPLICITLY COUPLED ELECTROMECHANICAL AND ELECTROMAGNETIC TRANSIENTS SIMULATOR FOR POWER SYSTEMS
Creator: Abhyankar, Shrirang
Date: 2011-11, 2011-11
Description: The simulation of electrical power system dynamic behavior is done using tran- sient stability simulators (TS) and electromagnetic transient...
Show moreThe simulation of electrical power system dynamic behavior is done using tran- sient stability simulators (TS) and electromagnetic transient simulators (EMT). A Transient Stability simulator, running at large time steps, is used for studying rela- tively slower dynamics e.g. electromechanical interactions among generators and can be used for simulating large-scale power systems. In contrast, an electromagnetic transient simulator models the same components in finer detail and uses a smaller time step for studying fast dynamics e.g. electromagnetic interactions among power electronics devices. Simulating large-scale power systems with an electromagnetic transient simulator is computationally inefficient due to the small time step size in- volved. A hybrid simulator attempts to interface the TS and EMT simulators which are running at different time steps. By modeling the bulk of the large-scale power system in a transient stability simulator and a small portion of the system in an electromagnetic transient simulator, the fast dynamics of the smaller area could be studied in detail, while providing a global picture of the slower dynamics for the rest of power system. In the existing hybrid simulation interaction protocols, the two simulators run independently, exchanging solutions at regular intervals. However, the exchanged data is accepted without any evaluation, so errors may be introduced. While such an explicit approach may be a good strategy for systems in steady state or having slow variations, it is not an optimal or robust strategy if the voltages and currents are varying rapidly, like in the case of a voltage collapse scenario. This research work proposes an implicitly coupled solution approach for the combined transient stability and electromagnetic transient simulation. To combine the two sets of equations with their different time steps, and ensure that the TS and EMT solutions are consistent, the equations for TS and coupled-in-time EMT equations are solved simultaneously. While computing a single time step of the TS equations, a simultaneous calculation of several time steps of the EMT equations is proposed. Along with the implicitly coupled solution approach, this research work also proposes to use a three phase representation of the TS network instead of using a positive-sequence balanced representation as done in the existing transient stability simulators. Furthermore a parallel implementation of the three phase transient stability simulator and the implicitly coupled electromechanical and electromagnetic transients simulator, using the high performance computing library PETSc, is presented. Re- sults of experimentation with different reordering strategies, linear solution schemes, and preconditioners are discussed for both sequential and parallel implementation.
Ph.D. in Electrical Engineering, December 2011
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Title: IMPROVED SPATIAL-TEMPORAL RECONSTRUCTION FOR CARDIAC AND RESPIRATORY GATED SPECT
Creator: Qi, Wenyuan
Date: 2014, 2014-12
Description: Myocardial perfusion single photon emission computed tomography (SPECT) is an important imaging technique for evaluating coronary artery...
Show moreMyocardial perfusion single photon emission computed tomography (SPECT) is an important imaging technique for evaluating coronary artery disease. It can provide information of both myocardial perfusion and ventricular function. However, SPECT images su er from both cardiac and respiratory motion blur. In order to reduce the motion degrading, cardiac and respiratory gated SPECT imaging is used. In gated SPECT imaging, due to the lowered counts, the gated images will be more noisy than the ungated ones. Spatiotemporal (4D) processing is often used to reduce the noise level in gated images. In this thesis, we aim to investigate spatial and temporal processing techniques for improving the quality in cardiac and respiratory gated SPECT imaging. First, we will investigate a piecewise spatial smoothing prior based on totalvariation (TV) in 4D cardiac SPECT image reconstruction. In previous studies, it was found that spatial smoothing could adversely a ect the accuracy of 4D reconstruction in cardiac gated SPECT when temporal smoothing was applied, even though it could suppress the noise level. Our goal is to explore whether a piecewise spatial smoothing prior will improve the image accuracy while reducing the noise. Toward this goal, we will compare TV based piecewise spatial smoothing with quadratic spatial smoothing with simulated imaging, in which we will evaluate the lesion detectability. Clinical data will also be used to compare the results as a preliminary test. Motion-compensated temporal smoothing is known to play a key role in 4D cardiac gated SPECT reconstruction. Next, we will investigate whether better motion estimation could further improve the accuracy of reconstructed images. We will consider two di erent motion estimation models and the known motion in simulated experiments. The motion estimation methods are the classic optical ow estimation (OFE) and a periodic motion estimation method. We will evaluate the reconstruction from di erent motion models using several numerical quanti cation metrics. Furthermore, we will demonstrate reconstruction with the two motion estimation models using clinical acquisitions. Respiratory motion is known to cause motion blur in SPECT image reconstruction, and respiratory gated SPECT imaging can be e ective to combat its e ect. We will develop reconstruction techniques in respiratory gated SPECT. We will consider two reconstruction schemes for respiratory gated SPECT. The rst scheme is a post motion compensated reconstruction, in which images at di erent respiratory phases are reconstructed seperately, and afterwards are averaged over all the respiratory gates by motion compensation. The second scheme is a model based motion compensated reconstruction approach, in which one reference gate is used to describe the acquisition data of all the respiratory gates. Due to irregular respiratory motion, the data acquisition in each respiratory gate is not uniformly distributed among the acquisition angles, which would lead to limited-angle artifacts. To correct such artifacts, we propose an angle compensation method in the reconstruction. In order to deal with both cardiac and respiratory motion, we will investigate a 4D reconstruction approach for dual cardiac-respiratory gated SPECT reconstruction. This approach can accommodate the acquired data simultaneously from di erent cardiac and respiratory gates. It can exploit the correlation in the signal component among both the cardiac and respiratory phases. Both simulated experiments and clinical reconstruction will be used for evaluating this reconstruction approach. Due to the radiation risk of myocardial perfusion imaging (MPI) scans, there is an urgent need to lower the radiation dose used in SPECT. However, lower radiation dose will lead to more noisy reconstruction, which is even more serious in gated SPECT. We would explore the potential of using 4D reconstruction for lowering the dose in dual cardiac-respiratory gated SPECT.
Ph.D. in Electrical and Computer Engineering, December 2014
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Title: ADVANCED TRACER KINETIC MODELS FOR IMPROVED TUMOR MARGIN DETECTION AND GUIDING THERAPY
Creator: Sinha, Lagnojita
Date: 2014, 2014-07
Description: Cancer continues to be the second leading cause of death in the world with one in two individuals suffering from some form of cancer within...
Show moreCancer continues to be the second leading cause of death in the world with one in two individuals suffering from some form of cancer within their lifetimes [1]. The main objective in most cancer therapies is to achieve a complete resection of the cancerous cells, which in surgical approaches is evident from the diagnosis of positive resection margins during postoperative pathology. However, pathological analysis is performed after the patient has been discharged. Thus technologies capable of identifying tumor margins in resected samples intraoperatively could substantially reduce the psychological and economical burden of “call-back” surgeries. As a step in this direction, a wide-field Raman spectroscopy system was employed, which has the capacity to discriminate between tumor and healthy tissue through a “dual-tracer” staining approach within the surgical window. The approach entails dipping the resected tissue in two tracers: one targeted to a cancer specific cell-surface receptor, and another left “untargeted”. In this experiment human glioma (U251) and human epidermoid (A431) tumors were grown subcutaneously in ten nude athymic mice. The data obtained from the Raman spectra of different tissue specimens were then analyzed through tracer kinetic modeling to quantify cancer molecule abundance as a surrogate of cancer presence. The salient finding in this study was that the model was able to predict the expected differences in EGFR concentration amongst the healthy tissue, U251, and A431. Kinetic model estimation of the ratio of EGFR concentration in U251 and A431 cell lines were in the ratio of 2:1, which correlates, with the expected ratio of EGFR concentration determined by flow cytometry which was close to 4:1. This technology not only promises to xii highlight tumor margins on a molecular level but can also be leveraged to analyze the molecular environment of the tumor to guide adjuvant precision therapies. Tracer kinetic modeling approaches were also applied to a guided precision therapy called Photodynamic therapy. Not only could the analysis of data provide parameter values for the tracer kinetics but an approach was also developed which with only a few initial data points could predict the time optimal for therapy in advance of the drug concentration maximum.
M.S. in Electrical Engineering, July 2014
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