Search results

Title: The Effect of Entropy on Texture Recognition Based on the GLCM Method.
Creator: Wang, Penghui, DeBrunner, Victor E., DeBrunner, Linda S., Harvey, Bruce A., Florida State University, FAMU-FSU College of Engineering, Department of Computer and Electrical...
Show moreWang, Penghui, DeBrunner, Victor E., DeBrunner, Linda S., Harvey, Bruce A., Florida State University, FAMU-FSU College of Engineering, Department of Computer and Electrical Engineering
Show less
Abstract/Description: In order to better study how to improve the accuracy of texture recognition in image processing, we will study the concept of information entropy, which characterizes the uncertainty of the information source. Since the information entropy value of different images and local parts of an image are different, we wonder whether the information entropy will contain some features suitable for distinguishing the different textures of images. If so, we can improve the accuracy of texture recognition...
Show moreIn order to better study how to improve the accuracy of texture recognition in image processing, we will study the concept of information entropy, which characterizes the uncertainty of the information source. Since the information entropy value of different images and local parts of an image are different, we wonder whether the information entropy will contain some features suitable for distinguishing the different textures of images. If so, we can improve the accuracy of texture recognition by using the information entropy. When we mention texture, people will think of the wood grain on wooden furniture immediately, or the decorative pattern on flowery cloth, and so on. Wood grain is a natural texture, while the decorative pattern is an artificial texture. They both reflect some changes of the surface color and grayscale throughout the image. These changes are characteristics of the image itself. The texture is very important, but difficult part of image processing. The recognition and selection of texture features is always a difficult problem to quantity in the field of image processing. In recent years, with the texture in high resolution remote sensing images, medical image detection, as well as in the textile industry, it has an increasingly wide range of applications. Therefore, it is very critical to study the directions in texture recognition research. In this thesis, we design an experiment to obtain the effect of entropy on texture recognition. The main texture analysis method used in this experiment is the gray level co-occurrence matrix (GLCM) method. This is a method to describe texture by analyzing the spatial correlation characteristics of grayscale images and to recognize the texture by these features. In this thesis, we will select 5 original images with different textures. We generate 1000 different sub-images after image segmentation as training and test samples from these original images. By constructing the GLCM matrix for each sub-image, texture features of each sub-image can be obtained, and then appropriate texture features can be selected through feature extraction and feature selection. Then, half of these samples were added with entropy as a new texture feature, and the other half were not added with entropy. Finally, we determine the accuracy of these two types of classification using a standard classifier. Thus, we can obtain the effect of entropy in texture recognition based on the GLCM method.
Show less
Date Issued: 2019
Identifier: 2019_Fall_Wang_fsu_0071N_15439
Format: Thesis

Title: Combined Electrical and Thermal Models for Integrated Cryogenic Systems of Multiple Superconducting Power Devices.
Creator: Satyanarayana, Sharath R. (Sharath Raghav), Pamidi, Sastry V., Foo, Simon Y., Bernadin, Shonda, Florida State University, College of Engineering, Department of Electrical and...
Show moreSatyanarayana, Sharath R. (Sharath Raghav), Pamidi, Sastry V., Foo, Simon Y., Bernadin, Shonda, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: High Temperature Superconducting (HTS) technology is a potential option for applications that require high power densities for lightweight and compact solutions for transportation systems such as electric aircrafts and all-electric Navy ships. Several individual HTS power devices have been successfully demonstrated for these systems. However, the real benefit lies in providing the system level design flexibility and operational advantages with an integrated cryogenic system. A centralized...
Show moreHigh Temperature Superconducting (HTS) technology is a potential option for applications that require high power densities for lightweight and compact solutions for transportation systems such as electric aircrafts and all-electric Navy ships. Several individual HTS power devices have been successfully demonstrated for these systems. However, the real benefit lies in providing the system level design flexibility and operational advantages with an integrated cryogenic system. A centralized cryogenic cooling technology is being explored to serve multiple HTS devices in a closed loop system. This provides high efficiency and permits directing the cooling power to where it is needed depending on the mission at hand which provides operational flexibility. Design optimization, risk mitigation and the operational characteristics under various conditions need to be studied to increase the confidence level in HTS technology. Development of simpler and cost-efficient cryogenic systems are essential to make HTS systems attractive. Detailed electrical and cryogenic thermal models of the devices are also necessary to understand the of risks in HTS power systems and to devise mitigation techniques for all the potential failure modes. As the thermal and electrical characteristics of HTS devices are intertwined, coupled thermal and electrical models are necessary to perform system level studies. To enable versatile and fast models, the thermal network method is introduced for cryogenic systems. The effectiveness of the modelling technology was demonstrated using case studies of multiple HTS devices in a closed loop cryogenic helium circulation system connected in different configurations to access the relative merits of each configuration. Studies of transient behavior of HTS systems are also important to understand the response of a large HTS system after one of the cryogenic cooling components fails. These studies are essential to understand the risks and potential options in the design or in operations to mitigate some of the risks. Thermal network models developed in this study are also useful to study the temperature evolution along the whole system as a function of time after a component fails. The models are useful in exploring the design options to extend the time of operation of a device such as a HTS cable after the failure of the cryogenic system.
Show less
Date Issued: 2018
Identifier: 2018_Su_Satyanarayana_fsu_0071N_14787
Format: Thesis

Title: Learning and Motion Planning for Gait-Based Legged Robots.
Creator: Harper, Mario Yuuji, Erlebacher, Gordon, Collins, E., Beaumont, Paul M., Clark, Jonathan E., Shanbhag, Sachin, Meyer-Bäse, Anke, Florida State University, College of Arts and...
Show moreHarper, Mario Yuuji, Erlebacher, Gordon, Collins, E., Beaumont, Paul M., Clark, Jonathan E., Shanbhag, Sachin, Meyer-Bäse, Anke, Florida State University, College of Arts and Sciences, Department of Scientific Computing
Show less
Abstract/Description: Animals have demonstrated the capacity to traverse many complex unstructured terrains at high speeds by utilizing effective locomotion regimes. Motion in difficult and uncertain environments have only seen partial success on traditional wheeled or track-based robots and is limited to slow deliberative maneuvers on legged robots, which are focused on maintaining continuous stability through proper foothold selection. While legged robots have demonstrated successful navigation across many...
Show moreAnimals have demonstrated the capacity to traverse many complex unstructured terrains at high speeds by utilizing effective locomotion regimes. Motion in difficult and uncertain environments have only seen partial success on traditional wheeled or track-based robots and is limited to slow deliberative maneuvers on legged robots, which are focused on maintaining continuous stability through proper foothold selection. While legged robots have demonstrated successful navigation across many complex surfaces, motion planning algorithms currently fail to consider the unique mobility characteristics that honor the natural self-stabilizing dynamics of gait-based locomotion such as running and climbing. This dissertation outlines some of the specific motion planning challenges faced when attempting to plan for legged systems with dynamic gaits, with specific instances of these demonstrated by four robots, the dynamic running platforms: XRL, LLAMA, Minitaur and the dynamic climbing platform TAILS. Using a unique implementation of Sampling Based Model Predictive Optimization (SBMPO) designed expressly for dynamic legged robots, we demonstrate the ability to learn kinodynamic models, motion plan through obstacles on varied terrains and demonstrate navigation on vertical walls. This research has pioneered the technique which allows dynamic legged robots to navigate while honoring the natural dynamics of robot gait. Further, this document will describe to the reader the methods and algorithms that enabled Florida State University to be the first in the world to demonstrate motion planning on a dynamic climbing robot. This work is demonstrated in simulation and verified through hardware experiments on canonical motion planning scenarios, controlled laboratory settings and in unstructured terrains. Finally, this work has opened the field of dynamic legged robot intelligence for future researchers by enabling fundamental navigation and planning, efficient real-time algorithms for onboard computing, and the development of techniques to account for complex constrained motions unique to individual robots and terrains.
Show less
Date Issued: 2018
Identifier: 2018_Fall_Harper_fsu_0071E_14735
Format: Thesis

Title: Security Evaluation of Tree Parity Re-Keying Machine Implementations Utilizing Side-Channel Emissions.
Creator: Martinez Padilla, Jonathan E., Meyer-Baese, U., Meyer-Bäse, Anke, Foo, Simon Y., Yu, Ming, Florida State University, FAMU-FSU College of Engineering, Department of Electrical...
Show moreMartinez Padilla, Jonathan E., Meyer-Baese, U., Meyer-Bäse, Anke, Foo, Simon Y., Yu, Ming, Florida State University, FAMU-FSU College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: In this work, Side-Channel Attacks (SCAs) are considered as a security metric for the implementation of hybrid cryptosystems utilizing the neural network-based Tree Parity Re-keying Machines (TPM). A virtual study is presented within the MATLAB environment that explores various scenarios in which the TPM may be compromised. Performance metrics are evaluated to model possible embedded system implementations. A new algorithm is proposed and coined as Man-in-the-Middle Power Analysis (MIMPA) as...
Show moreIn this work, Side-Channel Attacks (SCAs) are considered as a security metric for the implementation of hybrid cryptosystems utilizing the neural network-based Tree Parity Re-keying Machines (TPM). A virtual study is presented within the MATLAB environment that explores various scenarios in which the TPM may be compromised. Performance metrics are evaluated to model possible embedded system implementations. A new algorithm is proposed and coined as Man-in-the-Middle Power Analysis (MIMPA) as a means to copy the TPM's generated keys. It is shown how the algorithm can identify vulnerabilities in the physical device in which the cryptosystem is implemented by using its power emissions. Finally, a machine learning approach is used to identify the capabilities of neural networks to recognize properties of keys produced in the TPM as they are transferred to an encryption algorithm. The results show that physical exploits of TPM implementations in embedded systems can be identified and accounted for before a final release. The experiments and data acquisition is demonstrated with an implementation of a TPM-hybrid cryptosystem in an AVR microcontroller. Additionally, obfuscation methods are explored in the form of control transformations. A tool is created utilizing FLEX and GCC to add opaque predicates into VHDL source code. The study incorporates the transformations into concurrent and sequential statements. A trade-off between cost and potency is seen in concurrent statements, while no cost is used in sequential statements all while retaining its original behavior.
Show less
Date Issued: 2018
Identifier: 2018_Sp_MartinezPadilla_fsu_0071E_14442
Format: Thesis

Title: Modeling and Application of Effective Channel Utilization in Wireless Networks.
Creator: Ng, Jonathan, Yu, Ming (Professor of scientific computing), Zhang, Zhenghao, Harvey, Bruce A., Andrei, Petru, Florida State University, College of Engineering, Department of...
Show moreNg, Jonathan, Yu, Ming (Professor of scientific computing), Zhang, Zhenghao, Harvey, Bruce A., Andrei, Petru, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: As a natural scarcity in wireless networks, radio spectrum becomes a major investment in network deployment. How to improve the channel utilization (CU) of the spectrum is a challenging topic in recent research. In a network environment, the utilization of a channel is measured by the effective CU (ECU), i.e., the effective time for transmission or when the medium being sensed busy over its total operation time. However, existing work does not provide a valid model for ECU. We investigate the...
Show moreAs a natural scarcity in wireless networks, radio spectrum becomes a major investment in network deployment. How to improve the channel utilization (CU) of the spectrum is a challenging topic in recent research. In a network environment, the utilization of a channel is measured by the effective CU (ECU), i.e., the effective time for transmission or when the medium being sensed busy over its total operation time. However, existing work does not provide a valid model for ECU. We investigate the relationship between ECU and the interference from other wireless transmission nodes in a wireless network, as well as from potential malicious attacking interfering sources. By examining the relationship between their transmission time and co-transmission time ratios between two or more interferers, we propose a new model based on the channel occupation time of all nodes in a network. The model finds its mathematical foundation on the set theory. By eliminating the overlapping transmission time intervals instead of simply adding the transmission time of all interferers together, the model can obtain the expected total interference time by properly combining the transmission time of all individual nodes along with the time when two or more nodes transmit simultaneously. Through dividing the interferers into groups according to the strength levels of their received interference power at the interested node, less significant interfering signals can be ignored to reduce the complexity when investigating real scenarios. The model provides an approach to a new detection method for jamming attacks in wireless networks based on a criterion with combined operations of ECU and CU. In the experiments, we find a strong connection between ECU and the received interference power and time. In many cases, strong and frequent interference is accompanied by a declination of ECU. The descending slope though may be steep or flat. When the decrease of ECU is not significant, CU can be observed with a sharp drop instead. Therefore, the two metrics, ECU and CU when properly combined together, demonstrate to be an effective measurement for judging strong interference. In addition, relating to other jamming detection methods in the literature, we build a mathematical connection between the new jamming detection conditions and PDR, the Packet Delivery Ratio, which has been proved effective by previous researchers. Thus, the correlation between the new criteria and PDR guarantees the validity of the former by relating itself to a tested mechanism. Both the ECU model and the jamming detection method are thoroughly verified with OPNET through simulation scenarios. The experiment scenarios are depicted with configuration data and collected statistical results. Especially, the radio jamming detection experiments simulate a dynamic radio channel allocation (RCA) module with a user-friendly graphical interface, through which the interference, the jamming state, and the channel switching process can be monitored. The model can further be applied to other applications such as global performance optimization based on the total ECU of all nodes in a wireless communications environment because ECU relates one node's transmission as the interference for others using the same channel for its global attribute, which is our work planned for the next step. We would also like to compare its effectiveness with other jamming detection methods by exploring more extensive experiment research.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Ng_fsu_0071E_14083
Format: Thesis

Title: Real-Time Fetal ECG System Design Using Embedded Microprocessors.
Creator: Muddu, Harikrishna, Meyer-Baese, Uwe H., Foo, Simon Y., Bernadin, Shonda Lachelle, Florida State University, FAMU-FSU College of Engineering, Department of Electrical and...
Show moreMuddu, Harikrishna, Meyer-Baese, Uwe H., Foo, Simon Y., Bernadin, Shonda Lachelle, Florida State University, FAMU-FSU College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: Monitoring the fetal ECG (FECG) gives us important information about the fetal wellbeing. FECG is a complex waveform where each of the P through T complexes provides wealth of information. The objective of this project is to develop the best state-of-art real-time FECG monitoring system using embedded microprocessors. Many researchers from various fields like signal processing, artificial intelligence, and advanced statistics, have applied different techniques to extract FECG from the mixture...
Show moreMonitoring the fetal ECG (FECG) gives us important information about the fetal wellbeing. FECG is a complex waveform where each of the P through T complexes provides wealth of information. The objective of this project is to develop the best state-of-art real-time FECG monitoring system using embedded microprocessors. Many researchers from various fields like signal processing, artificial intelligence, and advanced statistics, have applied different techniques to extract FECG from the mixture of MECG and other noises and calculate the FHR, with accuracy as an objective. Most of them are calculation intensive and not real-time. The proposed approach focuses mainly on real time processing, robustness and portability of the system. The work discussed here will provide a novel algorithm to extract FECG from abdominal ECG (AECG) which is mixture of FECG, MECG, and noise, and finding Fetal FHR with less number of dimensions (measurements) with the best signal-to-noise ratio. This approach is tested on different soft-core processors and results are compared with other commercial of-the-shelf (COTS) hardcore solutions, in terms of power, cost, size and speed. In the end FECG was successfully extracted and identified on the basis of BPM and SNR values calculated using this method. It was found that hard-core processor (ARM Cortex A9) has achieved the best real-time performance among all.
Show less
Date Issued: 2016
Identifier: FSU_FA2016_Muddu_fsu_0071N_13633
Format: Thesis

Title: Energy Efficient Routing Algorithms in Wireless Sensor Networks.
Creator: Dong, Yizhou, Yu, Ming, Zhang, Zhenghao, Harvey, Bruce A., Andrei, Petru, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Abstract/Description: A wireless sensor network (WSN) consists of a large number of low-cost sensors that can communicate to each other for specific applications. Sensor nodes are spatially distributed in a large region and operated in an autonomous manner. Each sensor node in the network is battery-limited and irreplaceable for most applications. Compared to the existing ad-hoc networks, significant problems have been raised. How to efficiently consume the energy to obtain a long lifetime of the network? How to...
Show moreA wireless sensor network (WSN) consists of a large number of low-cost sensors that can communicate to each other for specific applications. Sensor nodes are spatially distributed in a large region and operated in an autonomous manner. Each sensor node in the network is battery-limited and irreplaceable for most applications. Compared to the existing ad-hoc networks, significant problems have been raised. How to efficiently consume the energy to obtain a long lifetime of the network? How to design routing algorithms to adaptively accommodate the change in energy? How to reconsider the energy-efficiency issue if the renewable energy devices are involved? How to mathematically model these problems and validate solutions by simulations and experiments? We investigate these questions and present our models, designs, algorithms, and results in the dissertation. Research on WSNs is driven by specific applications but the applications of WSN have been widely divergent in recent years. Environmental monitoring and surveillance is a major application, in which the WSN is implemented to monitor a large geographic area that is usually unexplored or potentially dangerous area, such as forests, rivers, and desert. It is especially challenging when the infrastructure of the environment is unknown. The sensors for this application are irreplaceable and thus the battery life becomes crucially important. Military applications are designed to support communications among soldiers, military vehicles, and headquarters. For example, in a battlefield, the coordination among a groups of soldiers has to be well-established in any complicated situation. An interesting paradigm is animal monitoring, in which small sensors are placed on animals to surveil their habitat. The sensors carried by animals form a mobile ad hoc network to collect and transmit data. The difficulties of this application are that the sensors must be lightweight enough for animals while the topology of the network is always changing. Also, there are other emerging applications like body health monitoring, disaster recovery, and underwater robot-assisted exploration. In this work, we have two major related research topics. One is the energy-efficient design and optimization of the application-specific routing protocols to maximize the network lifetime of a WSN. Another is the optimization and design of the routing protocol for energy harvesting wireless sensor network (EHWSN) by predicting the condition of energy harvesting in the near future. For the first topic, the key issue is how to conserve energy to maintain the network connectivity as long as possible, or maximize the lifetime of the network. One common solution is to design a routing algorithm that can cope with the changes of network conditions and dynamically adjust the routing strategy or switch the operation modes to save energy. Many routing metrics have to be considered including transmission distance, residual energy, link capacity, etc. Energy-efficient routing protocols have been well investigated with the goal of maximizing the network lifetime, which is usually defined as the time when the first node dies. Once a node becomes unavailable due to energy depletion, its data transmissions in the network are assumed to fail. In our work, we consider the network remains alive as long as the energy is enough to maintain the flows of the application traffic, which is more reasonable since the network can still function even without those "dead" nodes. Instead of universally balancing the energy consumption over the entire network, we aim at locally optimizing the energy-efficiency of the target nodes on the application flows. Essentially, it’s an energy trade-off between the target nodes and other irrelevant nodes, in which the former will expend more energy than the latter on the application flows for energy-efficiency. Therefore, the routing algorithm can be designed to save more energy on routes of the specific traffic. We present a novel application-specific and energy-efficient routing algorithm to maximize the lifetime of the application flows in WSNs. Firstly, we formulate the routing problem as a linear programming problem, which can be converted to a max-min fairness problem. Secondly, the lifetime of a flow is evaluated in terms of the link metrics including residual energy, transmission rate, and link distance. Thirdly, a heuristic routing algorithm is proposed to compute the best route that minimizes the cost of application flows. Simulation results have shown that our routing algorithm prolong the lifetime of flows around 10%. For the second topic, compared to a conventional WSN, which is strictly limited by its battery supply of the sensor nodes, EHWSN is an environmentally powered network that brings new techniques and challenges to the energy-efficiency topic. By harvesting the ambient or renewable energy feasible to WSN, a tremendous breakthrough can be made to improve the energy-efficiency and the network lifetime. Environment usually has a large variety of the energy sources, such as solar, wind, mechanical, thermal, and biochemical sources. Some major issues have been raised in order to take advantage of energy harvesting. For instance, how to schedule and allocate the energy consumption by predicting the energy availability? How to jointly consider the energy-efficiency and network lifetime? How to design a prediction model for energy harvesting in order to achieve a better performance? We find a critical issue in current routing algorithms for EHWSN, in which the calculated routes are frequently alternating because of the uncertainty of the energy availability in the near future. Without knowing the future harvesting condition, the current algorithms calculate the most energy-efficient routes based on the past and current condition. The uncertainty may lead to energy waste and extra network overheads. In our work, we propose to predict the energy harvesting condition in the near future and estimate whether the current optimal routes can be maintained by the harvested energy in a certain time threshold. If yes, we temporarily restrict the data transmission and receiving to reduce the energy cost by using parameters, which are determined by the availability and intensity of the future harvesting. Comprehensive factors are considered to predict the energy condition in near future and help make routing decisions including residual energy, harvest energy, and energy consumption. We first give an example to illustrate the motivation of our energy prediction-based routing problem. Second, we formulate the problem as a linear optimization problem and convex optimization problem with analytical proof depending on prediction models. Third, we propose a heuristic routing algorithm to maximize the volume of collected data from the network. Fourth, the routing algorithm is implemented and verified by Matlab and OMNET++ simulation. The results indicate that the proposed algorithm can largely improve the energy-efficiency and reduce the network overheads. In summary, we propose to solve the energy-efficiency issues in both application-specific WSN and EHWSN. For application-specific WSN, the network lifetime is extended by our routing algorithm, which aims at minimizing the energy consumption of the target nodes rather than the entire network nodes. The results shows a 10% improvement on network lifetime. For EHWSN, the network throughput is increased by a predictable energy-efficient routing algorithm, which considering the harvested energy in the near future. The results demonstrate that the both network throughput and lifetime are increased.
Show less
Date Issued: 2016
Identifier: FSU_FA2016_Dong_fsu_0071E_13219
Format: Thesis

Title: Soft Error Event Monte Carlo Modeling and Simulation: Impacts of Soft Error Events on Computer Memory.
Creator: Ogden, Christopher, Mascagni, Michael V., Duke, D. W. (Dennis W.), Kumar, Piyush, Florida State University, College of Arts and Sciences, Department of Computer Science
Abstract/Description: This dissertation addresses the creation of a unique, adaptable, and light-weight core methodology to address the problem of Soft Error Modeling and Simulation. This core methodology was successfully tailored, validated, and expanded to work with a diverse cross-section of realistic memory devices, reliability techniques, and soft error event behaviors. These devices were shielded by a mutually supporting trio of reliability techniques while under the threat of soft error events. The...
Show moreThis dissertation addresses the creation of a unique, adaptable, and light-weight core methodology to address the problem of Soft Error Modeling and Simulation. This core methodology was successfully tailored, validated, and expanded to work with a diverse cross-section of realistic memory devices, reliability techniques, and soft error event behaviors. These devices were shielded by a mutually supporting trio of reliability techniques while under the threat of soft error events. The techniques included in this dissertation are: (1) error correction codes, (2) interleaving distance, and (3) scrubbing. The strike-times, soft error event types, and bit error severities of the Soft Error Events were stochastically estimated using publicly available research findings published from a variety of proprietary reliability data sources. This proprietary data was gathered from certain secret vendor-specific computer memory devices. Both logically-oriented and physically-oriented memory cell organizational perspectives were incorporated into the core-methodology that was tailored to create the Simulators implemented within this dissertation. The failure probabilities of memory devices were calculated by the simulators that were designed and implemented within this dissertation. The results of these simulations were validated for specific test cases against the published literature models. This core methodology was applied to create scalable Simulators that were implemented utilizing a variety of soft error event behavioral characteristics, memory device design constraints, and reliability technique parameters. This core methodology and the simulators created from its application may be utilized by researchers to address a variety of open research questions in the field. An open research question was answered within this dissertation as proof of the effectiveness of the core methodology. This particular research question concerned establishing the significance of Soft Error Event (SEE) topography by studying the impact of Topographically reflective SEEs on the overall failure probability and corresponding reliability of the simulated memory device over time. To address this open research question, the Topographic 2-Parameter Weibull Soft Error (T2P-WSE) Simulator stochastically estimates the topographic strike-patterns of SEE severities based on the most commonly encountered Multiple Cell Upset shapes gathered by a commercial grade 3D-TCAD-based Neutron Particle Strike Simulation in a generic 45 nm SRAM (Static Random Access Memory) memory device. Both the failure probability and reliability results generated by the Topographic 2-Parameter Weibull Soft Error (T2P-WSE) Simulator were shown to be significantly different from the Row-Depth-Only 2-Parameter Weibull Soft Error Simulator (S2P-WSE) when given equivalent inputs. As documented within this dissertation, this conclusion was verified and confirmed from both a visual and statistical standpoint. Topography was observed to play a significant role in the overall failure probability of the device. It was concluded that the failure probability of the T2P-WSE Simulator was significantly reduced in comparison to the failure probability of the S2P-WSE Simulator. As defined for a variety of input parameters, the S2P-WSE Simulator consistently over-estimated the failure probability of the device. The reason for this outcome is directly related to the row-depth-only bit error severity assumption of the S2P-WSE Simulator. The row-depth-only assumption forces every MCU SEE impacts the device to spread its bit errors in a fixed row-depth-only pattern as opposed to a more realistic topographic pattern incorporated such as the patterns encoded into the T2P-WSE Simulator for the 45 nm memory chip geometry. This conclusion only served to reinforce the initial observation that when taking into account the spread of the bit errors, one would significantly reduce the overall failure probability for a memory storage device implemented with an interleaving distance architecture by taking into account its topographic shape. The core methodology calls for the stochastic estimation of the strike-time, type, and bit-error severity that represent all simulated soft error events destined to impact the simulated device at some simulation time unit over the total simulation run-time. These Soft Error Events will strike the device at the appointed strike-time and be mitigated by the chosen set of mutually supporting reliability techniques. These reliability techniques include the following: (1) error correcting codes, (2) interleaving distance, and (3) scrubbing. This core methodology was fitted to the Compound Poisson and a logical memory cell organization for the Compound Poisson Soft Error Simulator. This core methodology was also successfully applied to the 2 Parameter Weibull Failure Distribution and a Physical Memory Cell organization. Both CPSE and S2P-WSE Simulators proved equally capable in calculating the failure probability of any variety of simulated memory storage devices shielded by the three integrated reliability techniques under the Impact of these stochastically determined soft error events. This failure probability over simulated time was utilized to evaluate all of the secondary results of the Core Methodology including such results as the Mean-Time-To Failure and Failures-In-Time Number at the conclusion of each simulation run. All of the simulators presented within this dissertation were implemented within a Matlab programming environment.
Show less
Date Issued: 2016
Identifier: FSU_2016SU_Ogden_fsu_0071E_13415
Format: Thesis

Title: A New Scheme for Emergency Message Dissemination in Vehicular Ad Hoc Network.
Creator: Zhang, Chenqi, Yu, Ming, Harvey, Bruce A., Kwan, Bing Woon, Florida State University, College of Arts and Sciences, Department of Electrical and Computer Engineering
Abstract/Description: Emergency message dissemination (EMD) in vehicular ad hoc network (VANET) becomes a hot topic due to the ever increasing concern on the road safety. When encountering unusual situations, emergency messages should be disseminated quickly to as many vehicles as possible in order to avoid any potential accidents. For this application, two basic requirements are low latency and high reliability [23]. In urban area, EMD application can be applied with roadside devices (e.g. using a base station to...
Show moreEmergency message dissemination (EMD) in vehicular ad hoc network (VANET) becomes a hot topic due to the ever increasing concern on the road safety. When encountering unusual situations, emergency messages should be disseminated quickly to as many vehicles as possible in order to avoid any potential accidents. For this application, two basic requirements are low latency and high reliability [23]. In urban area, EMD application can be applied with roadside devices (e.g. using a base station to broadcast). But in the areas that infrastructures are difficult to be deployed and maintained, multi-hop broadcast is the main technique used in this application. However, multi-hop broadcast scheme leads to broadcast storm problem in dense traffic. Several approaches have been proposed to solve this problem. They can be classified as distanced-based, cluster-based, and probability-based approaches. In distance-based approaches, vehicles that farther from the source vehicle are selected as relay nodes in order to achieve a better cover area. In cluster-based approaches, each cluster has a cluster head which is used as the relay node. The cluster is self-organized and the cluster head is selected according to information such as vehicle's speed, direction, location, and antenna height. Both distance-based and cluster-based approaches require the maintenance of the network topology. For probability-based approaches, vehicles don't care about the network topology or their neighbors’ information. A vehicle decides its probability to broadcast based on the information contained in the received packet. This thesis analyzes the existing protocols and points out the issues of the existing approaches. For the issues, we present a novel probability-based broadcast scheme that can inhibit broadcast storm, decrease the end-to-end delay, and guarantee that the emergency messages are delivered to most of the vehicles. The rest of the thesis is structured as follows. In chapter 1 we introduce the concept of VANET and remaining issues of the existing methods for EMD. The research problem in this work is defined and several related works are reviewed. In chapter 2, we analyze the probability-based protocol and proposed our protocol in detail. The typical probability-based protocol [13] uses a linear function to determine whether or not a vehicle should broadcast. However, it doesn't perform well in dense traffic in term of end-to-end delay. Our protocol uses an exponent function instead of the linear function in probability-based approaches. The simulation results show that our protocol can shorten the end-to-end delay in dense traffic without impacting the reliability. In chapter 3, we present the network model and simulation results, including the tools used for the simulation. Especially, key parameters of the proposed protocol are discussed. The simulation results as well as network performance analysis are presented in chapter 4. In chapter 5, we conclude this work. The remaining problems and future work of the proposed protocol are summarized in this chapter.
Show less
Date Issued: 2016
Identifier: FSU_2016SU_Zhang_fsu_0071N_13382
Format: Thesis

Title: Evaluation of a Benchmark Suite Exposing Android System Complexities Using Region-Based Caching.
Creator: Brown, Martin Kenneth, Tyson, Gary Scott, DeBrunner, Linda S., Whalley, David B., Yuan, Xin, Florida State University, College of Arts and Sciences, Department of Computer Science
Abstract/Description: The computer architecture community relies on standard benchmark suites like MiBench, NAS, PARSEC, SPEC CPU2006 (SPEC)®, and SPLASH to study different hardware designs, but such suites are insufficient for evaluating mobile platforms like Android. Even suites that were developed for embedded systems cannot be used to gain an understanding of Android device/system interaction because they do not exercise key components of the software stack. Although based on a conventional Linux ® kernel,...
Show moreThe computer architecture community relies on standard benchmark suites like MiBench, NAS, PARSEC, SPEC CPU2006 (SPEC)®, and SPLASH to study different hardware designs, but such suites are insufficient for evaluating mobile platforms like Android. Even suites that were developed for embedded systems cannot be used to gain an understanding of Android device/system interaction because they do not exercise key components of the software stack. Although based on a conventional Linux ® kernel, Android includes native libraries, a virtual machine runtime, and an application framework with multiple components for managing resources. All these interact in complex ways to support Android applications. C programs running on Linux have a relatively simple virtual memory organization, and most memory references come from the application code. In contrast, Android has a much more complex virtual memory organization (due to its multiple APIs and numerous shared libraries), and most memory references come from the Android software stack. The complexity of Android's execution environment provides opportunities for computer architects to better support the execution characteristics, structures, and resource requirements of the Android software stack and opportunities for software developers to optimize their applications for this rich environment. To help the community to exploit these opportunities, we introduce Agave, an open-source benchmark suite designed to expose the complex interactions between components of the Android software stack.
Show less
Date Issued: 2016
Identifier: FSU_FA2016_Brown_fsu_0071E_13594
Format: Thesis

Title: TAG: A Timing Adaptive Grouping Protocol for Smart Grid Communications.
Creator: Cai, Ziyuan, Yu, Ming, Li, Hui, Meyer-Baese, Anke, Steurer, Michael Morten, Andrei, Petru, Florida State University, College of Engineering, Department of Electrical and...
Show moreCai, Ziyuan, Yu, Ming, Li, Hui, Meyer-Baese, Anke, Steurer, Michael Morten, Andrei, Petru, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: The prospect of SG is green, power efficient, and economical to its customers. Many emerging innovations have reached a consensus that the traditional power grids need to be combined with modern data networks, in order to establish a new platform that supports distributed renewable energy devices, electrical measuring sensors, and intelligent energy management and control systems, etc. For example, an energy management system is proposed to connect data aggregators with renewable energy...
Show moreThe prospect of SG is green, power efficient, and economical to its customers. Many emerging innovations have reached a consensus that the traditional power grids need to be combined with modern data networks, in order to establish a new platform that supports distributed renewable energy devices, electrical measuring sensors, and intelligent energy management and control systems, etc. For example, an energy management system is proposed to connect data aggregators with renewable energy devices in the network area. A wireless sensor network is used to provide the communications between SG data centers and consumers, and manage residential energy with an optimization-based scheme. In SG, the stability of an energy management scheme becomes heavily dependent on accurate real-time communications among intelligent energy management agencies in residential homes, micro-grids, and main grids. Within a large-scale distributed (or centralized) smart grid (SG), the communication network is designed to connect multiple power management systems and collect data from hundreds or thousands of power sensors over a wide geographical area. One dominant feature of innovated SG communication network is that one power device is coupled with a single Ethernet or non-Ethernet communication agent to exchange control state or management information with others. Generally speaking, an intelligent agent helps its corresponding power device negotiating with other peers to dynamically form an ad-hoc group through the data network infrastructures. Then, many meaningful power management algorithms are operated in the logical group. The grouping topology recognized by a specific agent needs to reform when the participating group members can not satisfy the demand from operating power management algorithms. Upon our ad-hoc ideas, the main problem arises: in a changed group, the networking size, traffic load, queueing effect and security requirement are varied, so an agent experiences different communication cost over group reforming. We define such inevitable difference as communication inconsistency of SG ad-hoc grouping. If the timeout parameters of communication control are set statically in grouping procedures, the inconsistency definitely triggers the timeout, crashes the group and aborts the running cycle of power management algorithms very often. Thus in this work, an adaptive timing solution is developed for connecting distributed intelligent agents in ad-hoc manner to greatly enhance the flexibility and performance of grouping algorithms in SG communication network. A timing adaptive grouping (TAG) protocol is proposed to make every distributed agent capable of adjusting its operational timing configurations (OTCs) in pace with the changing of ad-hoc groups, so that prevents the harmfulness of communication inconsistency to the stability of grouping procedures. More specifically, we first develop a set of queueing model to describe the network traffic of various power management applications among distributed agents in connection with different scale of ad-hoc grouping topologies. Second, the security cost of SG communications is modeled, estimated and validated with various grouping agents' characteristics. Third, based on the network grouping model including both queueing and security cost, we analyze the ad-hoc delay performance and illustrate that the model can be used to predict the average operating delays of networking agents. Fourth, based on the delay parameters derived from previous modeling, the TAG protocol is developed with our Smart Timing Adaptive (STA) algorithm to facilitate each distributed agent dynamically judging variant ad-hoc grouping conditions. Finally, we have implemented a validation testbed with the capabilities of integrated real-time communication and power exchange to demonstrate the ad-hoc grouping operation of SG power management applications. Due to the ripple effect of inconsistent communication delays among the ad-hoc SG groups with dynamic changing topology, the network performance becomes a major concern to support power management applications. To deal with that, in a large NSF project of Future Renewable Electric Energy Delivery and Management (FREEDM), we implement a SG prototype, called the FREEDM Hardware-in-the-loop (HIL) testbed. The so-called Distributed Grid Intelligences (DGIs) act as the distributed intelligent agents in the SG prototype which can group specific peers to exchange power load among power demands and supplies. There are also many other existing works contributing a variety of platforms to integrate power and communication systems. But, in our FREEDM project, we build a SG testbed, which is a new platform that combines an HIL power system and a real-time communication system. The power system devices are managed by the DGIs that are connected into the communication networks. The DGIs act as intelligent energy management agencies for the power system, while information nodes for the communication networks. The DGI instances are coded on embedded computer boards with processing and communication capabilities. A DGI represents its power device to communicate with other DGI instances or DGI nodes. DGIs being connected in LAN and WAN may be grouped together to meet the power demand and supply requirement. A DGI group may cover a LAN, or a LAN and WAN simultaneously, depending on the location of DGI nodes. When electrical faults isolate a section from the power system, in communicational sense, the section is still connected to and can exchange the information of grid states with other sections in the power system. The real-time and HIL features of the testbed are reflected in the design of both power and communication systems. To implement the concept of HIL in the power system, some power devices are implemented by real-world electrical hardware, while other devices are simulated in the Real Time Digital Simulator (RTDS) platform. To implement the concept of HIL in the communication system for the DGIs, the DGI LANs are implemented by Ethernet switches, while the DGI WAN is simulated in real-time by OPNET, a network simulator program. Within OPNET, there is a system-in-the-loop (SITL) interface that interprets DGI traffic between real packet formats and simulated formats.
Show less
Date Issued: 2015
Identifier: FSU_migr_etd-9562
Format: Thesis

Title: Identification of the Inertial Parameters of Manipulator Payloads.
Creator: Reyes, Ryan-David, Department of Electrical and Computer Engineering
Abstract/Description: Momentum based motion planning allows small and lightweight manipulators to lift loads that exceed their rated load capacity. One such planner, Sampling Based Model Predictive Optimization (SBMPO) developed at the Center for Intelligent Systems, Control, and Robotics (CISCOR), uses dynamic and kinematic models to produce trajectories that take advantage of momentum. However, the inertial parameters of the payload must be known before the trajectory can be generated. This research utilizes a...
Show moreMomentum based motion planning allows small and lightweight manipulators to lift loads that exceed their rated load capacity. One such planner, Sampling Based Model Predictive Optimization (SBMPO) developed at the Center for Intelligent Systems, Control, and Robotics (CISCOR), uses dynamic and kinematic models to produce trajectories that take advantage of momentum. However, the inertial parameters of the payload must be known before the trajectory can be generated. This research utilizes a method based on least squares techniques for determining the inertial parameters of a manipulator payload. It is applied specifically to a two degree of freedom manipulator. A set of exciting trajectories, i.e., trajectories that sufficiently excite the manipulator dynamics, in task space will be commanded to the system. Inverse kinematics are then used to determine the desired angle, angular velocity, and angular acceleration for the manipulator joints. Using the sampled torque, joint position, velocity, and acceleration data, the least squares technique produces an estimate of the inertial parameters of the payload. This paper focuses on determining which trajectories produce sufficient excitation so that an adequate estimate can be obtained.
Show less
Date Issued: 2014
Identifier: FSU_migr_uhm-0418
Format: Thesis

Title: Real-Time Switched Reluctance Machine Emulation via Magnetic Equivalent Circuits.
Creator: Fleming, Fletcher, Edrington, Chris S., Ordonez, Juan, Foo, Simon, Meyer-Baese, Uwe, Weatherspoon, Mark H., Department of Electrical and Computer Engineering, Florida State...
Show moreFleming, Fletcher, Edrington, Chris S., Ordonez, Juan, Foo, Simon, Meyer-Baese, Uwe, Weatherspoon, Mark H., Department of Electrical and Computer Engineering, Florida State University
Show less
Abstract/Description: Electrical power systems utilizing electromagnetic devices, namely those of electrical ships, are subject to nonlinearities from regenerative loads, distributed energy storage systems, and onboard loads such as air handling and fluid pumps. Thus, accurate and timely electromagnetic (EM) device models are required in order to fully assess the impact of such transient and/or nonlinear activity. Specifically, by exploiting an often overlooked technique, i.e. the magnetic equivalent circuit (MEC)...
Show moreElectrical power systems utilizing electromagnetic devices, namely those of electrical ships, are subject to nonlinearities from regenerative loads, distributed energy storage systems, and onboard loads such as air handling and fluid pumps. Thus, accurate and timely electromagnetic (EM) device models are required in order to fully assess the impact of such transient and/or nonlinear activity. Specifically, by exploiting an often overlooked technique, i.e. the magnetic equivalent circuit (MEC) modeling method, a solution of adequate granularity for the EM device may be attained while still obeying a faster time commitment when compared to the simulation standard for EM devices, the finite element analysis (FEA) technique. The Hardware in the Loop (HIL) concept synergizes with expedient modeling methods, potentially allowing a wider range of dynamics to be observed in large scale simulations or even tested hardware systems. By scaling down the next generation all electric ships integrated power system (NGIPS) to a power level suitable for an academic laboratory environment, the nonlinear effects of EM devices may be investigated via the HIL concept and the MEC modeling method, given that the runtime is acceptable. This work proposes to develop a novel "real time" MEC (RT MEC) machine model, to ensure the aforementioned runtime. A switched reluctance machine (SRM) is used as a case study device due to both its inherent nonlinearity and it providing an ideal foundation for incorporating various characteristics of the MEC modeling technique. The proposed RT MEC concept will be implemented on a field programmable gate array (FPGA). The advantages of FPGA realization include the inherently parallel nature, a substantially cheaper real time (RT) platform when compared to computationally efficient FEA methods that require dedicated, elaborate resources and application specific hardware. Furthermore, FPGA realization provides a fully customizable solution in terms of numerical methods, time step, HIL interfacing and system expansion. The primary contribution of this work is the RT MEC methodology; more specifically, a high fidelity, real time platform exploited for dynamic SRM modeling, an undoubtedly nonlinear device. RT-MEC contributes higher accuracy and lighter computational loads when compared to commercially available modeling techniques adhering to similar time constraints; ultimately, this yields faster simulation times and more accurate HIL simulation or Power Hardware in the Loop (PHIL) emulations. Further exercising the RT MEC concept, a variety of novel applications can arise that are uniquely capable of accentuating the nonlinear intricacies and effects assimilated into machine connected systems. Expanding, RT MEC can provide a state of the art tool useful for assessing overall system impact when subjected to electromechanical transients, control strategies and power electronics; providing pertinence and merit to the principal contribution. Potential applications include investigating the nonlinear effects of loading the NGIPS via a PHIL implementation, emulated via SRM winding pulses or utilizing SRM RT MEC models with large scale wind system simulations to study the impact an SRM motor type has on wind farm design.
Show less
Date Issued: 2014
Identifier: FSU_migr_etd-8987
Format: Thesis

Title: A Particle Swarm Optimization Based Maximum Torque Per Ampere Control for a Switched Reluctance Motor.
Creator: Griffin, Lee, Edrington, Chris S., Andrei, Petru, Moss, Pedro, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The Switched Reluctance Machine (SRM) is known for being one of the oldest electric machine designs. Unfortunately, it is usually assumed that this implies that the machine is outdated. However with the advent of microprocessors, the SRM has become a suitable option for a number of applications because the shortcomings of the machine can be mitigated with control. Compared to other machines, the SRM is more rugged, has a simpler structure, and is less expensive to manufacture. The machine has...
Show moreThe Switched Reluctance Machine (SRM) is known for being one of the oldest electric machine designs. Unfortunately, it is usually assumed that this implies that the machine is outdated. However with the advent of microprocessors, the SRM has become a suitable option for a number of applications because the shortcomings of the machine can be mitigated with control. Compared to other machines, the SRM is more rugged, has a simpler structure, and is less expensive to manufacture. The machine has two control regions: when the speed of the machine is beneath a value called the base speed and when the speed is above the base speed. The base speed is the speed at which the back electromotive force (EMF) of the motor becomes substantial when compared to the source voltage. In both regions, the turn-on and turn-off angles of the machine can be used to control the machine. This thesis proposes a method of generating optimal turn-on and turn-off angles. The method presented in this thesis is concerned with finding the turn-on and turn-off angles needed to generate maximum torque per ampere (MTA). The strategy applies a particle swarm optimization (PSO) technique that searches for the angles that maximize the inductance of the SRM in order to achieve MTA. The inductance function was obtained via Finite Element Analysis (FEA) and experimentally. The method was applied to a 4-phase 8/6 SRM. The proposed strategy was found to be effective at both low speeds (beneath the base speed) and high speeds (above the base speed), but MTA could only be asserted for low speeds.
Show less
Date Issued: 2014
Identifier: FSU_migr_etd-8994
Format: Thesis

Title: Experimental and Mathematical Modeling Studies on Current Distribution in High Temperature Superconducting DC Cables.
Creator: Pothavajhala, Venkata, Edrington, Chris, Graber, Lukas, Andrei, Petru, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: High temperature superconducting power cables have the advantage of high current density and low losses over conventional cables. One of the factors that affect the stability and reliability of a superconducting cable is the distribution of current among the tapes of cable. Current distribution was investigated as a function of variations in contact resistance, individual tape critical current (Ic), and index (n)-value of individual tapes. It has been shown that besides contact resistances,...
Show moreHigh temperature superconducting power cables have the advantage of high current density and low losses over conventional cables. One of the factors that affect the stability and reliability of a superconducting cable is the distribution of current among the tapes of cable. Current distribution was investigated as a function of variations in contact resistance, individual tape critical current (Ic), and index (n)-value of individual tapes. It has been shown that besides contact resistances, variations in other superconducting parameters affect current distribution. Variations in critical current and n-value become important at low contact resistances. The effects of collective variations in contact resistances, individual tape Ic, and n-values were studied through simulations using Monte Carlo method. Using an experimentally validated mathematical model, 1000 cables were simulated with normally distributed random values of contact resistances, individual tape Ics, and n-values. Current distribution in the 1000 simulated cables demonstrated the need for selecting tapes with a narrow distribution in the superconducting parameters to minimize the risk of catastrophic damage to superconducting cables during their operation. It has been demonstrated that there is a potential danger of pushing some tapes closer to their Ic before the current in the cable reaches its design critical current. Mathematical models were also used to study the effect of longitudinal variations in the tape parameters on superconducting cable using Monte Carlo simulations. Each tape of a 30 meter long, 3 kA model cable with 30 tapes was considered to have longitudinal variations in Ic, and n values for every 1 cm section, thus generating particular standard deviation in Ic and n for all 3000 sections of each tape. The results indicate that the apparent critical current and index value of the cable are reduced by a certain percentage depending upon the extent of variation in the characteristics along the length of the tapes.
Show less
Date Issued: 2014
Identifier: FSU_migr_etd-9071
Format: Thesis

Title: Corrosion Detection by Induction.
Creator: Roddenberry, Joshua L., Arora, Rajendra K., Foo, Simon, Roberts, Rodney, Andrei, Petru, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Bridges in Florida are exposed to high amounts of humidity due to the state's geography. This excess moisture results in a high incidence of corrosion on the bridge's steel support cables. Also, the inclusion of ineffective waterproofing has resulted in additional corrosion. As this corrosion increases, the steel cables, responsible for maintaining bridge integrity, deteriorate and eventually break. If enough of these cables break, the bridge will experience a catastrophic failure resulting...
Show moreBridges in Florida are exposed to high amounts of humidity due to the state's geography. This excess moisture results in a high incidence of corrosion on the bridge's steel support cables. Also, the inclusion of ineffective waterproofing has resulted in additional corrosion. As this corrosion increases, the steel cables, responsible for maintaining bridge integrity, deteriorate and eventually break. If enough of these cables break, the bridge will experience a catastrophic failure resulting in collapse. Repairing and replacing these cables is very expensive and only increases with further damage. As each of the cables is steel, they have strong conductive properties. By inducing a current along each group of cables and measuring its dissipation over distance, a picture of structural integrity can be determined. The purpose of this thesis is to prove the effectiveness of using electromagnetic techniques to determine cable integrity. By comparing known conductive values (determined in a lab setting) to actual bridge values, the tester will be able to determine the location and severity of any damage, if present.
Show less
Date Issued: 2014
Identifier: FSU_migr_etd-8877
Format: Thesis

Title: Recap Antenna Synthesis and Optimization Using Backpropagation and Radial-Basis Function Artificial Neural Networks.
Creator: Langoni, Diego, Weatherspoon, Mark H., Meyer-Baese, Anke, Foo, Simon Y., Andrei, Petru, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: A 4x2 microstrip square patch antenna array, designed to operate in the 5.3 GHz range, was characterized and simulated using finite-element method (FEM) based models in COMSOL Multiphysics as a reconfigurable aperture (RECAP) antenna by controlling the excitation of each element individually. Based on the FEM models, backpropagation (BP) and radial-basis function (RBF) artificial neural networks (ANNs) were developed to: a) synthesize the response parameters, based on changes in the operating...
Show moreA 4x2 microstrip square patch antenna array, designed to operate in the 5.3 GHz range, was characterized and simulated using finite-element method (FEM) based models in COMSOL Multiphysics as a reconfigurable aperture (RECAP) antenna by controlling the excitation of each element individually. Based on the FEM models, backpropagation (BP) and radial-basis function (RBF) artificial neural networks (ANNs) were developed to: a) synthesize the response parameters, based on changes in the operating parameters (reconfigurable state and frequency), and b) optimize the reconfigurable state based on desired response parameter levels and frequency. The ANNs were tested using the training data (6630 patterns), and with test-only data (78 patterns). The results show that the RBF ANN architectures generate more favorable results in terms of reproducing the outputs used for training. However, the BP ANN architectures generated better results in terms of generalizing the outputs used only for testing. In terms of synthesis, the ideal balance of efficiency and accuracy was found by using multiple networks in tandem to synthesize the corresponding response parameters, with almost no loss in generality.
Show less
Date Issued: 2014
Identifier: FSU_migr_etd-8830
Format: Thesis

Title: Analysis of Threshold Voltage Fluctuations Induced by Random Doping in Metal-Oxide-Semiconductor Field-Effect-Transistors.
Creator: Zhou, Hui, Andrei, Petru, Zheng, Jim P., Li, Hui, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The stochastic nature of ion implantation and diffusion processes induces variations of random doping concentration, which result in the fluctuations of the intrinsic parameters of semiconductor devices. The fluctuations of intrinsic parameters become especially significant when the devices are scaled down, particularly when the spatial scale of random dopants variations becomes comparable with the geometric dimensions of device. In the thesis, the fluctuation of threshold voltage induced by...
Show moreThe stochastic nature of ion implantation and diffusion processes induces variations of random doping concentration, which result in the fluctuations of the intrinsic parameters of semiconductor devices. The fluctuations of intrinsic parameters become especially significant when the devices are scaled down, particularly when the spatial scale of random dopants variations becomes comparable with the geometric dimensions of device. In the thesis, the fluctuation of threshold voltage induced by random doping in metal-oxide-semiconductor field-effect-transistors (MOSFETs) is analyzed by using a simple technique based on the solution of the two- dimension and three-dimension nonlinear Poisson equation. The two-dimension nonlinear Poisson equation is solved by solving the Jacobian matrix using Newton iteration technique. The three-dimension nonlinear Poisson equation is solved by a more efficient iterative method. This iterative method converges for any initial guess and can be implemented on computers with small memories. Both methods are both implemented in the C++ programming language. Sample simulation results are obtained and compared with the analytical results.
Show less
Date Issued: 2014
Identifier: FSU_migr_etd-8924
Format: Thesis

Title: Fault Isolation in Power Electronic Based Distribution Systems without Circuit Breakers.
Creator: Widener, Christopher, Edrington, Chris S., Steurer, Mischa, Zheng, Jim, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: In the Future Renewable Electric Energy Distribution and Management (FREEDM) system, solid state Fault Isolation Devices (FIDs) are used to react to signals from a fault detection and location system to isolate faulted sections of a fault current limited power electronics based 12.47 kV distribution system. They accomplish this by interrupting fault currents, which in the FREEDM system are limited by Solid State Transformers (SST). However, as was expected, due to its silicon transistor...
Show moreIn the Future Renewable Electric Energy Distribution and Management (FREEDM) system, solid state Fault Isolation Devices (FIDs) are used to react to signals from a fault detection and location system to isolate faulted sections of a fault current limited power electronics based 12.47 kV distribution system. They accomplish this by interrupting fault currents, which in the FREEDM system are limited by Solid State Transformers (SST). However, as was expected, due to its silicon transistor technology, the developed FID prototype demonstrated rather high on-state losses during its operation. Therefore, it is necessary to perform comparison studies with alternative methods of sectionalizing faulted parts of the FREEDM grid. To respond to this need, a system study has been undertaken to explore an alternative fault isolation strategy, which instead of allowing fault currents to remain in the system uses the abilities of the SSTs to completely turn off fault currents. Once this turn-off has been accomplished, regular mechanical disconnects isolate the faulted section and the system is reenergized. Behavioral 3-phase PSCAD average-value SST models have been developed and are used in a representative model of the FREEDM Green Hub to demonstrate how this strategy would operate. Simulation data is presented that shows how the SSTs would react to fault situations, remove fault currents, and reenergize the system. The characteristic example system was constructed and parameterized allowing for sensitivity analyses to be performed. A comparison is made with the fault-current-breaking FID method of fault isolation currently in use and it is discussed how the presented approach can be used to evaluate future FREEDM fault isolation strategies.
Show less
Date Issued: 2014
Identifier: FSU_migr_etd-8912
Format: Thesis

Title: Phenomenological Equivalent Circuit Modeling of Various Energy Storage Devices.
Creator: Greenleaf, Michael C., Zheng, Jim, Shih, Chiang, Li, Helen, Andrei, Petru, Moss, Pedro, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: In this body of work, various energy storage devices have been modeled using phenomenological equivalent circuit modeling and impedance spectroscopy. Through this impedance-based modeling various electrochemical energy storage devices were modeled, providing accurate simulations of performance, as well as characterizing specific electrochemical processes and properties inherent in each system.
Date Issued: 2014
Identifier: FSU_migr_etd-8794
Format: Thesis

Title: Application of Artificial Intelligence to Rotating Machine Condition Monitoring.
Creator: Nyanteh, Yaw Dwamena, Edrington, Chris S., Cartes, David A., Oates, William, Roberts, Rodney, Andrei, Petru, Srivastava, Sanjeev K., Department of Electrical and Computer...
Show moreNyanteh, Yaw Dwamena, Edrington, Chris S., Cartes, David A., Oates, William, Roberts, Rodney, Andrei, Petru, Srivastava, Sanjeev K., Department of Electrical and Computer Engineering, Florida State University
Show less
Abstract/Description: Systems with critical functionality and are prone to damage due to excessive stress level from operation conditions and working environment requires health monitoring. Condition or health monitoring involves acquiring data that can be analyzed to determine the occurrence of faults, determine the type of fault, determine the severity of a fault and determine when the next fault would occur. This research has considered new fault analysis techniques for rotating electrical machines using...
Show moreSystems with critical functionality and are prone to damage due to excessive stress level from operation conditions and working environment requires health monitoring. Condition or health monitoring involves acquiring data that can be analyzed to determine the occurrence of faults, determine the type of fault, determine the severity of a fault and determine when the next fault would occur. This research has considered new fault analysis techniques for rotating electrical machines using Artificial Intelligence (AI) techniques. The analysis has been carried out in three sections: fault diagnosis, fault detection and fault prognosis. By way of fault diagnosis, Finite Element Analysis (FEA) has been used to model different faults in a Permanent Magnet Synchronous Machine (PMSM) which has been analyzed by way of classification using five Artificial Intelligence Techniques. The original large dimensional dataset is first used in the classification process and the different fault classifiers compared based on their performance using different fault classifiers from the FEA model. The dimensions of the dataset are reduced, using four different manifold reduction techniques. Manifold reduction is carried out to reduce the computational burden of fault classification on high dimensionality data. Two new techniques for fault detection using AI is presented and applied to PMSMs by way of computer simulations and experimental data from an actual PMSM. One technique called the Peak-to-Peak technique uses an Artificial Neural Network (ANN) trained using PSO and can distinguish short circuit faults from loading transients. In the second method, called Turn-to-Turn method, the zero current components is used to determine the number of shorted turns in the stator windings using an ANN trained using the Extended Kalman Filter (EKF) method. Finally a new method of determining the time-to-breakdown of insulation systems is presented as a fault prognosis approach. Also a new micro simulation model is presented for simulating the breakdown of dielectric materials. The new prognostics method is based on a macro model developed in conjunction with ANNs. The prognosis approach is based on associating the breakdown characteristics of dielectrics to Partial Discharge (PD) that take place during dielectric breakdown.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-8713
Format: Thesis

Title: Applications of Compressive Sampling for Reconstruction in Side-Scan Sonar Imagery.
Creator: Skinner, Dana E., Foo, Simon, Meyer-Baese, Anke, Hilton, Amy Chan, Meyer-Baese, Uwe, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The Nyquist-Shannon sampling theorem states that in order to reconstruct a compressed image, the number of samples needed must match the desired resolution. In other words the signal must be sampled at a rate at least twice the largest bandwidth in order to avoid aliasing. However it is possible and mathematically proven that compressive sampling (CS) can defy this theorem. The basic idea behind compressive sampling is to transform the image or signal into a suitable basis function and then...
Show moreThe Nyquist-Shannon sampling theorem states that in order to reconstruct a compressed image, the number of samples needed must match the desired resolution. In other words the signal must be sampled at a rate at least twice the largest bandwidth in order to avoid aliasing. However it is possible and mathematically proven that compressive sampling (CS) can defy this theorem. The basic idea behind compressive sampling is to transform the image or signal into a suitable basis function and then carry out only the important expansion coefficients. CS is incomplete without a suitable method for reconstruction. Theoretically, reconstruction relies on the minimization and optimization techniques to solve this complex almost NP-complete problem. There are many paths to consider when compressing and reconstructing an image but these methods have remained untested and unclear on natural images, such as underwater sonar images. The majority of the research remains in the medical imaging area. In our proposed work, we test current methods of reconstruction versus an alternative optimization algorithm that has yet to be used in compressive sampling, specifically the cross entropy method. Our focused application is on maintaining pertinent information, such as mine-like objects or tumor-like areas, in Side-scan sonar (SSS) images, magnetic resonance imaging (MRI) and mammography, respectively. Currently the JPEG-2000, a multi-level discrete wavelet transform, is the industry standard in image compression but this post processing could be avoidable with compressive sampling. A more efficient process of compression during the sampling stage and post processing reconstruction for SSS images has remained untested. Hence the motivation is to test current and new methods on SSS images, along with medical images for a baseline. The proposed methods can be a competitive alternative to the industry standard of post processing using the wavelet based JPEG-2000 and JPEG on SSS images, MRI and mammography. The final proposed work introduces a new method to denoise SSS images. This method solves the popular Total Variation (TV) problem by splitting the energies of the l1 and l2-norms. The resulting image will have a higher resolution and, depending on the parameters chosen, will be smoother.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-8717
Format: Thesis

Title: Novel High Energy Density Li-Ion Capacitors.
Creator: Cao, Wanjun, Zheng, Jim P., Shih, Chiang, Li, Hui, Foo, Simon Y., Andrei, Petru, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The energy density of conventional electric double-layer capacitors is about 6-7 Wh/kg and due to the limited specific capacitance and cell voltage, and a large amount of electrolyte which is required to build a layer of charge of the double-layer. The energy density theory guide clearly shows that the energy density of double-layer capacitors is ultimately limited by how many ions are available in the electrolyte or the salt concentration in the electrolyte.We demonstrate a lithium capacitor...
Show moreThe energy density of conventional electric double-layer capacitors is about 6-7 Wh/kg and due to the limited specific capacitance and cell voltage, and a large amount of electrolyte which is required to build a layer of charge of the double-layer. The energy density theory guide clearly shows that the energy density of double-layer capacitors is ultimately limited by how many ions are available in the electrolyte or the salt concentration in the electrolyte.We demonstrate a lithium capacitor which is capable of achieving high energy density over 20 Wh/kg, long cycle life and high power density. The lithium capacitor consists of a battery electrode with lithium intercalated hard carbon anode and a double-layer activated carbon cathode electrode with the open-circuit potential at or near the maximum potential when the cell is fully charged. The stabilized lithium metal powder was applied onto the surface of prefabricated hard carbon anode electrodes.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7742
Format: Thesis

Title: Advanced Isolated Bi-Directional DC-DC Converter Technology for Smart Grid Applications.
Creator: Liu, Xiaohu, Li, Hui, Ordonez, Juan, Meyer-Baese, Uwe H., Zheng, Jim P., Edrington, Chris S., Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The growing concerns for environment, increasing demand growth and threat of energy shortage continue to accentuate the request of upgrading the traditional power grid. Smart grid is envisioned to take advantage of all available modern technologies in transforming the current grid to one that functions more intelligently to facilitate integration of renewable energy source and energy storages, to provide higher quality of service and so on. Solid State Transformer (SST) is an essential...
Show moreThe growing concerns for environment, increasing demand growth and threat of energy shortage continue to accentuate the request of upgrading the traditional power grid. Smart grid is envisioned to take advantage of all available modern technologies in transforming the current grid to one that functions more intelligently to facilitate integration of renewable energy source and energy storages, to provide higher quality of service and so on. Solid State Transformer (SST) is an essential technology for integration of the distributed energy resources, distributed energy storage, and intelligent loads. It has the advantages of its reduced size and weight/volume with high frequency transformer, high power density, and good power quality. Comparing to other SST topologies, the three-stage SST is more promising due to its advantages to provide power factor correction, reactive power compensation and an additional regulated DC bus The bi-directional dc-dc converter is the key stage in the three-stage SST topology configuration since it provides not only the high frequency galvanic isolation, but also determines the system overall efficiency and power density. Therefore, the dc-dc converter promising dynamic performance is the key requirement for the three-stage SST. Currently, few literatures research on the three-stage SST system dynamics, especially for the soft start-up issue. Three-stage SST requires a delicate start-up control scheme because of three conversion stages and high frequency transformer. The major challenge of researching start-up issue is how to develop a theoretical analysis strategy to study different schemes. The thesis researches this issue by formulating the transformer instaneous peak current with respects to all the key impact factors. As a result, different schemes can be investigated by using a unified formula. Moreover, a new soft start-up scheme is proposed with the minimized transformer current response. The thorough analysis of the DC-DC converter transformer current during the three-stage SST start-up and the proposed start-up scheme is described in details in chapter 2. Fuel cell is an important renewable energy source of distributed energy storage device for new mobile applications and power generation system since it offers high efficiency, low emissions of regulated pollutants and excellent part-load performance. The major challenge for fuel cell power conditioning system is to limit the fuel cell low-frequency current ripple resulted from the inverter load. The traditional solution is to adopt the large electrolytic capacitor as the energy buffer. However, the large-sized electrolytic capacitors will decrease the system lifetime as well as increase the system volume and cost. A new current-fed phase-shift controlled dc-dc converter based fuel cell power conditioning system is proposed in this thesis with low-frequency ripple free input current using a control-oriented power pulsation decoupling control scheme. Without adding any extra components, the proposed fuel cell converter realizes the power pulsation decoupling function so as to reduce the dc bus capacitor, thus allowing for choosing long lifetime film capacitor to replace the bulky electrolytic capacitor. The proposed decoupling control design is based on the system small-signal average model. The detailed system operation analysis and proposed decoupling control design guideline is presented in chapter 3. The chapter 4 summarizes the dissertation work.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-8709
Format: Thesis

Title: Single and Multiple Coaxial Inputs to a Cylindrical Waveguide for Far Field MRI at 21.1 Tesla.
Creator: Sagaram, Smriti, Grant, Samuel C., Arora, Rajendra K., Weatherspoon, Mark H., Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Most clinical Magnetic Resonance Imaging (MRI) techniques use body coils for near field excitation and detection of an RF signal at 64-128 MHz, corresponding to magnetic field scanners of 1.5-3 T. Use of these conventional RF coils for high field MRI (>7 T) becomes progressively more difficult because the shorter wavelengths are on the order of the size of the resonating cavity and sample size, causing wave interference effects not normally seen in near field operation. However, such...
Show moreMost clinical Magnetic Resonance Imaging (MRI) techniques use body coils for near field excitation and detection of an RF signal at 64-128 MHz, corresponding to magnetic field scanners of 1.5-3 T. Use of these conventional RF coils for high field MRI (>7 T) becomes progressively more difficult because the shorter wavelengths are on the order of the size of the resonating cavity and sample size, causing wave interference effects not normally seen in near field operation. However, such conditions lend themselves to far field operation. In traveling wave MRI, propagating RF fields are excited through an antenna located at a distance to a given sample such that excitation and detection in MRI can be induced in the far field using techniques developed in radar and communications applications. Numerous publications have utilized simple patch antennas integrated into 7 T human MRI scanners to image in the far field regime. At even higher fields, other excitation methods are available. For example, coaxial cable inputs are very simply implemented and can aid in both electromagnetic mode generation and the excitation of multiple simultaneously propagating RF waves. In this project, traveling wave MRI at ultra-high field is implemented using a concentric waveguide composed of a dielectric filled inner cylinder and an outer copper cylinder with dimensions similar to the magnet bore of 21.1 T ultra-wide bore magnet at National High Magnetic Field Laboratory, Tallahassee, Fl. Data was acquired from a simulated model of the system as well as from actual experiments for propagation instituted by coaxial inputs to the cylindrical waveguide.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7592
Format: Thesis

Title: Gas Turbine-Generator System Duality Study for Real-Time Phil Emulation Using Power Electronics Converters.
Creator: Soto, Dionne Miguel, Edrington, Chris S., Li, Hui, Roberts, Rodney, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Gas turbine-synchronous generator (GT-SG) systems are the main source of power and propulsion onboard most naval ships. Since this system plays a vital role in accomplishing the ship's mission, a lot of testing is conducted to ensure that the system is ideal for the ship in which it is to be installed. Testing of such systems is very expensive and complicated. These systems are very large in size and require a very large testing facility for storage. Also, it is a very complicated and high...
Show moreGas turbine-synchronous generator (GT-SG) systems are the main source of power and propulsion onboard most naval ships. Since this system plays a vital role in accomplishing the ship's mission, a lot of testing is conducted to ensure that the system is ideal for the ship in which it is to be installed. Testing of such systems is very expensive and complicated. These systems are very large in size and require a very large testing facility for storage. Also, it is a very complicated and high maintenance system. Therefore, it requires a lot of personnel for maintenance which further increases the total cost. Finding ways to reduce the cost and total amount of waste for testing these systems is essential for the day-to-day operation of the United States Navy. They have invested and continue to invest large sums of money in research which concentrates on finding reliable testing models which can potentially reduce the current cost and waste of testing such systems. The Energy Conversion and Integration trust (ECI) at the Center for Advanced Power Systems of Florida State University has developed a NLDL test bed. This test bed, shown in Appendix A, is comprised of real hardware developed converters for testing the Navy's All-Electric-Ship (AES) proposed power system. It is used to perform various tests on control and stability under the expected non-linear loads setting of the Navy's weapons systems. It can also be used to explore other research topics related to distributed power systems and other related hardware tests. The incorporation of this test bed is part of the next phase of this work which includes PHIL testing of the system. PHIL involves the use of incorporating physical power hardware to a simulation while CHIL refers to physically involving a controller with a simulated environment. Both forms of HIL allow for more in-depth validation techniques by actually involving the real hardware in simulation [1]. In this CHIL methodology, the simulated environment involves a real-time component model of the NLDL test bed where all parameters and components have been modeled to be an exact replica of the actual test bed in a RTDSTM system. The controller part of the CHIL involves the actual model of the GT-SG system which is computed in real time utilizing a RPC. In this particular work, the RPC is a dSPACETM unit. The CHIL methodology lays out the ground work and provides a link for the future implementation of PHIL. The CHIL method allows for testing of all communication links between the hardware. Therefore, once all the systems are tested and are operational, the hardware simulated environment can be replaced with the actual hardware of the NLDL test bed. As stated, this NLDL test bed is comprised of several power electronics converters such as Active-Front-End (AFE), Inverter (INV), and Neutral-Point-Clamp (NCP). The CHIL simulated hardware environment provides an exact replica of this test bed and is a great testing model for such a system. The purpose of this thesis is to utilize the AFE and INV to emulate the GT-SG system, and to provide a translation/duality between the GT-SG system variables (torque, speed, voltage, and current) and the AFE-INV system variables (voltages and currents) through the emulation methodologies. In this work, two methods which can be utilized to emulate any GT-SG system operation in a wide range of steady state, dynamic, and transient performance through the use of these power electronics converters, regardless of power level without loss of generality, are presented. The dynamic equations of the GT and SG are utilized to construct their models, and are implemented in MATLAB/Simulink®. The AFE is utilized to conduct the GT emulation and the INV is utilized to conduct the SG emulation. Controls are set up for the GT-SG model and the control signals are used to provide the switching commands for the AFE and INV, respectively, to perform the emulation. Parameter translation/duality between the GT-SG model and the AFE-INV model are also provided. For the purpose of this work, the GT-SG system studies and emulation are conducted in the distributed generation power levels. This work can/will be expanded to include the ship's main distribution power levels as part of the future work.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7611
Format: Thesis

Title: 2-Channel Low Power Broadband Transmit/Receive Switch and 720 Mhz High Power Narrow Pass Band Filter.
Creator: Mudela, Sai Kaushik, Foo, Simon, Brey, William W., Arora, Rajendra K., Weatherspoon, Mark H., Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Nuclear magnetic resonance (NMR) is an important tool used to study the atomic or molecular properties of nuclei by exploiting its magnetic properties. A spectrometer is an integral element of an NMR system which consists of a RF transmitter, receiver, amplifier, temperature controller, transmit/receive switch, filter, etc. A transmit/receive switch is used to toggle between transmission and reception modes of the resonant coil in the RF probe. The following thesis consists of the design and...
Show moreNuclear magnetic resonance (NMR) is an important tool used to study the atomic or molecular properties of nuclei by exploiting its magnetic properties. A spectrometer is an integral element of an NMR system which consists of a RF transmitter, receiver, amplifier, temperature controller, transmit/receive switch, filter, etc. A transmit/receive switch is used to toggle between transmission and reception modes of the resonant coil in the RF probe. The following thesis consists of the design and construction of one such T/R switch that is used to perform NMR field mapping of resistive magnets in the presence of temporal field fluctuations. This low power T/R switch consisting of two receive channels and a common transmitter is designed to operate over a wide range of proton (1H) NMR frequencies i.e., 200 MHz to 1600 MHz and can handle up to 1 watt power. It uses a micro strip transmission line design utilizing low power surface mount switches, splitters and drop-in preamps. The other part of this thesis deals with the design of a band pass filter tuned at 720 MHz. In multi nuclear pulsed NMR experiments, a high power band pass filter is used to improve the isolation between the channels of the spectrometer and screen out the other frequencies and noise signals from the system. The filter is designed using two semi-rigid coaxial cables grounded at their ends. This design is evaluated for its performance (insertion loss and reflection coefficient). The construction challenges have also been discussed. The filter is capable of handling a maximum RF input of 1 kilowatt rms power, has a 3dB bandwidth of 40 MHz and produces an insertion loss as low as 1dB.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7520
Format: Thesis

Title: Design and Modeling of Very High-Efficiency Multijunction Solar Cells.
Creator: Bhattacharya, Indranil, Foo, Simon Y., Meyer-Baese, Anke, Zheng, Jim P., Andrei, Petru, Li, Hui, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The main challenge in the solar cell industry is making the solar cells more cost effective. Mono and poly-crystalline Si, CdTe, CIGS, Quantum dot, Organic and Dye-sensitized solar cell technologies do not produce high efficiencies. A low bandgap semiconductor generates larger current due to photon absorption over broader spectral region but do not produce high open circuit voltage because it is limited by the dark current of the low bandgap material. This limits them within the Shockley...
Show moreThe main challenge in the solar cell industry is making the solar cells more cost effective. Mono and poly-crystalline Si, CdTe, CIGS, Quantum dot, Organic and Dye-sensitized solar cell technologies do not produce high efficiencies. A low bandgap semiconductor generates larger current due to photon absorption over broader spectral region but do not produce high open circuit voltage because it is limited by the dark current of the low bandgap material. This limits them within the Shockley efficiency limit of 30%. The relevant solutions are to increase the efficiency of solar cells, for example by effective spectral splitting by different bandgap semiconductor subcell layers, implementation of III-V direct bandgap optically sensitive and high carrier mobility semiconductors, form better matching (lattice, optical and electrical) between subcell layers, usage of concentrator Fresnel lenses and most importantly reduce the fabrication cost of the epitaxial layers. In this work we introduced two novel quadruple junction solar cell designs, each having four semiconductor subcell layers. We have simulated the quantum efficiency vs. wavelength, current density vs. voltage, power density vs. voltage and compared the photon absorption of our two novel designs with state of art single junction and multijunction solar cells. We showed that antimony based subcell layers help in higher photon absorption in the infrared (IR) region. Photonic modeling is implemented by the transfer-matrix method of wave propagation through multilayer structures. The first quadruple junction solar cell design comprises of AlGaInP (2.3eV) / InGaAs (1.1eV) / GaSb (0.7eV) / InGaSb (0.5eV) and the second design comprises of AlGaInP (2.3eV) / InGaP (1.93eV) / InGaAs (1.1eV) / InGaSb (0.5eV) III-V direct-bandgap semiconductor materials. The quadruple-junction subcell layers capture photons of ultraviolet (UV), visible, and near- and far infrared (IR) regions of the electromagnetic spectrum. The combination of our subcell layers yield favorable photon absorption results in comparison to the state of art solar cells.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7296
Format: Thesis

Title: Determination of Carbon Nanotube Thin Film Thickness and Optical Parameters by a New Modified Prism Waveguide Coupler System.
Creator: Baltas, Georgios, Liu, Tao, Andrei, Petru, Li, Hui, Yu, Ming, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Since their discovery by Iijima in 1991 carbon nanotubes have been used in many novel applications of nanotechnology. Carbon nanotubes thin films in particular can be used to create, among others, anti-reflection coatings or stretch sensors. However, for these applications to be successful the thickness of the film as well as its refractive index must be known. In this thesis a new system capable to measure the thickness and index of such films is proposed. Based on thin film optics, during...
Show moreSince their discovery by Iijima in 1991 carbon nanotubes have been used in many novel applications of nanotechnology. Carbon nanotubes thin films in particular can be used to create, among others, anti-reflection coatings or stretch sensors. However, for these applications to be successful the thickness of the film as well as its refractive index must be known. In this thesis a new system capable to measure the thickness and index of such films is proposed. Based on thin film optics, during 1969 Tien, Ulirch, and Martin first proposed a prism coupler method that could be used determine the characteristics of a transparent film by guiding light inside it. Based on their work Metricon corporation developed the first commercialized prism coupler instrument. Later, Liu developed a method called IRIA (Internal Reflected Intensity Analysis) that can be used to determine the characteristics of highly absorbing samples. Here based on the IRIA method a new modified prism coupler system is proposed. After the validity of the system's output is verified by comparing the acquired results with the results acquired from other methods, the new system is used to measure the thickness and the refractive index of single walled carbon nanotube thin films deposited on Polydimethylsiloxane substrates.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7285
Format: Thesis

Title: A Novel Method to Improve the Spatial Sample Rate of Synthetic Aperture Sonar.
Creator: Malphurs, David, Brooks, Geoffrey, Foo, Simon, Roberts, Rodney, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The along-track resolution of a sonar system is proportional to the aperture length in the along-track direction. Synthetic aperture sonar (SAS) coherently sum samples from multiple physical locations to form a synthesized aperture which exceeds practical physical aperture dimensions, offering improved resolution over physical aperture sonars of equivalent size. To avoid spatial under-sampling, single-transmitter SAS can move no more than one half of the along-track physical aperture length...
Show moreThe along-track resolution of a sonar system is proportional to the aperture length in the along-track direction. Synthetic aperture sonar (SAS) coherently sum samples from multiple physical locations to form a synthesized aperture which exceeds practical physical aperture dimensions, offering improved resolution over physical aperture sonars of equivalent size. To avoid spatial under-sampling, single-transmitter SAS can move no more than one half of the along-track physical aperture length between transmit pulses. This requirement creates a SAS "speed limit" which limits the area coverage rate of SAS. A method is introduced to increase the area coverage rate of SAS through the use of additional transmitters to form a multiple-input - multiple-output synthetic aperture sonar (MIMOSAS). By placing N transmitters spaced in the along-track direction and simultaneously transmitting non-correlating signals, the effective spatial sampling rate of SAS is increased and the SAS "speed limit" is increased by a factor of N. Finally, a novel spatial coding method is presented which reduces the self-noise created by multiple transmitters and improves the image quality in MIMOSAS systems.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7485
Format: Thesis

Title: Using Entropy to Improve the Resolution in Non-Parametric Spectral Estimation.
Creator: Liu, Guifeng, DeBrunner, Victor E., DeBrunner, Linda, Roberts, Rodney, Edrington, Chris, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Detection and estimation of frequencies in composite signal is a very important topic. The resolution issue is the most fundamental. The higher the resolution, the more precise information we can get from the signal. The traditional frequency detection and estimation is evaluated by conventional Discrete Fourier Transform (DFT) based periodogram. The basis of the DFT is the Heisenberg-Weyl measure, which quantifies the joint localization, uncertainty, or concentration of a signal in the phase...
Show moreDetection and estimation of frequencies in composite signal is a very important topic. The resolution issue is the most fundamental. The higher the resolution, the more precise information we can get from the signal. The traditional frequency detection and estimation is evaluated by conventional Discrete Fourier Transform (DFT) based periodogram. The basis of the DFT is the Heisenberg-Weyl measure, which quantifies the joint localization, uncertainty, or concentration of a signal in the phase plane based on a product of energies expressed as signal variances in time and in frequency. When the two frequency components are very close to each other in frequency, the two peaks in the periodogram will emerge, and it is hard for the DFT to distinguish between them. However the new proposed Hirschman Optimal Transform (HOT) based periodogram has the ability to resolve them. Unlike the Heisenberg-Weyl measure, the Hirschman notion of joint uncertainty is based on entropy rather than energy. Furthermore, its definition extends naturally from the case of infinitely supported continuous-time signals to the cases of both finitely and infinitely supported discrete-time signals. The HOT is superior to the DFT and Discrete Cosine Transform (DCT) in terms of its ability to separate or resolve two limiting cases of localization in frequency, viz pure tones and additive white noise. In this dissertation I implement a stationary spectral estimation using three methods: (1) matching pursuit method whose dictionary members are constructed from the combination of HOT-based and DFT atoms (elements). (2) filter bank method whose filter banks are constructed from HOT and DFT matrices. (3) compressive sensing method i.e Iterative Hard Thresholding (IHT) combined with matching pursuit and filter bank methods. I call the resulting algorithm the HOT-DFT (HF) periodogram. I compare its performance (in terms of frequency resolution) with a standard DFT-based periodogram. I find the HF to be superior to the DFT in frequency estimation, and ascribe the difference to the HOT's relationship to entropy.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7472
Format: Thesis

Title: The Next Generation Grid-Connected PV Inverters for High Penetration Applications.
Creator: Zhou, Yan, Li, Hui, Shih, Chiang, Foo, Simon Y., Zheng, Jim P., Meyer-Baese, Uwe, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The increasing consumer demand and government incentives are driving the rapid growth of renewable energy generation. In particularly, the number of distributed photovoltaic (PV) system installations is increasing quickly. However, the high cost of the PV systems and the potential impacts on the safe operation of utility grid could become barriers to their future expansion. To enable the high penetration of distributed PV systems, it is necessary to bring down the PV system cost and mitigate...
Show moreThe increasing consumer demand and government incentives are driving the rapid growth of renewable energy generation. In particularly, the number of distributed photovoltaic (PV) system installations is increasing quickly. However, the high cost of the PV systems and the potential impacts on the safe operation of utility grid could become barriers to their future expansion. To enable the high penetration of distributed PV systems, it is necessary to bring down the PV system cost and mitigate its adverse impacts on utility grid operation. As the interface between the renewable sources and the utility grid, advanced power electronics technologies will play important roles in realizing the above goals. The transformerless cascaded multilevel inverter (CMI) is considered to be a promising topology alternative for low-cost and high-efficiency PV systems. This research work presents a single-phase transformerless PV system based on cascaded quasi-Z-source inverters (qZSI). In this system, each qZSI module is connected to a single PV panel and serves as a PV module-integrated converter (MIC). The advantages of the proposed MIC structure include low voltage gain requirement, single-stage energy conversion, enhanced reliability and good output power quality. The innovative structure can reduce the cost and increase the efficiency of the power conversion stage. Furthermore, the enhancement mode gallium-nitride field effect transistors (eGaN FETs) are employed in the qZSI module for efficiency improvement at higher switching frequency. Optimized module design is developed based on the derived qZSI ac equivalent model and power loss analytical model to achieve high efficiency and high power density. A design example of qZSI module is presented for a 250 W PV panel with 25 V ~ 50 V output voltage. The simulation and experimental results prove the validity of the analytical models. The final module design achieves up to 98.06% efficiency with 100 kHz switching frequency. The peak efficiency can be further improved to 98.66% with synchronous rectification. Though the tranformerless CMI-based PV systems can achieve high performance and low cost, the leakage current issue resulted from the parasitic capacitors between the PV panels and the earth remains a challenging. In this research work, the leakage current paths in PV CMI are analyzed and the unique features are discussed. Two filter-based suppression solutions are then presented to tackle the leakage current issue in different PV CMI applications. The first method is more suitable for the CMIs operated at high switching frequency. The second method extends the application to the CMIs operated with lower switching frequency by bringing in extra wire connections among the cascaded modules and the grid output. Simplified leakage current analytical models are derived to study the suppression mechanisms and design the suppression filters. Study cases are demonstrated for each of the solutions. The first solution is applied to the above presented PV system based on cascaded qZSIs. The second solution is executed in a PV system with two cascaded H-bridges where each switching device is operated at 10 kHz. Simulation and experimental results are provided to validate the effectiveness of the proposed solutions. To mitigate the adverse impacts on utility grid operation associated with high penetration level of PV systems, an autonomous unified var controller is proposed to address the system voltage issues and unintentional islanding problems. The proposed controller features integration of both voltage regulation (VR) and islanding detection (ID) functions in a PV inverter based on reactive power control. Compared with the individual VR or ID methods, the function integration exhibits several advantages in high PV penetration applications: 1) fast voltage regulation due to the autonomous control; 2) enhanced system reliability because of the capability to distinguish between temporary grid disturbances and islanding events; 3) negligible non-detection zone (NDZ) and no adverse impact on system power quality for ID and 4) no interferences among multiple PV systems during ID. As the VR and ID functions are integrated in one controller, the controller is designed to fulfill the requirement of VR dynamic performance and ensure small ID NDZ simultaneously. The interaction among multiple PV systems during VR is also considered in the design procedure. The feasibility of the proposed controller and the controller design method is validated with simulation using a real time digital simulator (RTDS) and a power hardware-in-the-loop (PHIL) testbed. Finally, conclusions are given and the scope of future work is discussed.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-8674
Format: Thesis

Title: Fault Protection Framework Designs and Methods in Power Electronics Converter Based Power Distribution Systems.
Creator: Tatcho, Passinam Atong, Li, Hui, Steurer, Mischa, Erlebacher, Gordon, Edrington, Chris S., Yu, Ming, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Due to technology development and continued increase in energy demand while keeping the environment protected, renewable resources started emerging rapidly within the distribution system. Renewable resources help to maintain power quality and reliability, but in high penetration, they can adversely affect the system operation by causing overvoltage issues or interfering with existing fault protection technologies. The existing fault protection methods do not always apply in these new...
Show moreDue to technology development and continued increase in energy demand while keeping the environment protected, renewable resources started emerging rapidly within the distribution system. Renewable resources help to maintain power quality and reliability, but in high penetration, they can adversely affect the system operation by causing overvoltage issues or interfering with existing fault protection technologies. The existing fault protection methods do not always apply in these new distribution networks because of various reasons including cost, complexity of the system due to mesh-like network topology, presence of power electronics converters, and bidirectional power flow. In a system containing renewable resources, most fault protection technologies ignore the presence of the renewable resources by assuming either low penetration level or no power injection from renewable resources during a fault. The few fault protection technologies that consider the presence of renewable resources have not considered a network with power electronics (PE) converters that limit the fault current in the system. A fault protection system includes detection, location, and isolation of the faulted section and possible reconfiguration of the system. The work here is focused on fault detection and location because they present the challenging component of fault protection in a converter based distribution system with fault current limited. Isolation and reconfiguration are system dependent as they occur according to the physical arrangement of the system and the availability of resources. This thesis focuses on the design of a comparison framework which aims to help in choosing the most appropriate protection strategy for the system of interest. Because of the massive penetration of power electronics devices that interface with the renewable resources, the system of interest considered in this thesis is a fault current limited system. Considering the power rating, the line parameters, the converters, and the topology of the system, identify quantifiable characteristics of the system and derive a selection tree to help establish the most suitable protection scheme for the system. First, various meaningful influencing factors of existing fault protection detection and location are identified. In order to design a comparison framework, we consider the governing criteria for each protection scheme including some of the most common fault protection systems based on current only, voltage only, and current and voltage measurements. The sensitivity and selectivity of the protection scheme are also taken into consideration, and those characteristics are mapped to the current limiting system under study: the FREEDM system. "Smart Grid" concept is used to describe the idea of intelligently controlling renewable resources in the distribution system and all the other assets. Future Renewable Electric Energy Delivery and Management (FREEDM) system, which is one example of developing smart grid systems, is suitable for the study of the challenges related to fault protection technologies in a current limited system and the development of a fault location technology for significantly limited fault current system. Given the characteristics of the FREEDM system and the comparison framework developed, the differential pilot protection , the directional overcurrent protection , the directional overcurrent pilot section protection , and the voltage profile based protection3 were all chosen to be implemented on a fault current limited distribution system. The directional overcurrent pilot section protection was proposed to overcome the coordination issues that arise with the directional overcurrent protection therefore, making it faster. However, the small residual voltage remains a challenge for both directional protection technologies while the differential pilot protection is challenged by the large amount of measurements that need to be synchronized and processed. Thus, another fault location strategy is developed for converters based systems with fault current limited. This strategy takes advantage of the system topology, the presence of the controllable PE converters, and the change of the voltage profile with the presence of the fault.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-8647
Format: Thesis

Title: FPGA-Based Model of a High-Frequency Power Electronic Converter in an RTDS Based Power System Co-Simulation.
Creator: Meka, Raveendra, DeBrunner, Linda S., Steurer, Michael, Yu, Ming, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The aim of the thesis is to include a Field Programmable Gate Array (FPGA) based electromagnetic transient simulation into a Real-time Digital Simulator (RTDS) power system simulation. This will enable the simulation of high-frequency components of power electronic converters such as DC-DC converters which were not previously resolvable using only RTDS simulator. The FPGAs support parallel hardware designs with high clock rates, allowing fast computation of the models. The approach of co...
Show moreThe aim of the thesis is to include a Field Programmable Gate Array (FPGA) based electromagnetic transient simulation into a Real-time Digital Simulator (RTDS) power system simulation. This will enable the simulation of high-frequency components of power electronic converters such as DC-DC converters which were not previously resolvable using only RTDS simulator. The FPGAs support parallel hardware designs with high clock rates, allowing fast computation of the models. The approach of co-simulation is to divide and distribute components of a complex power system onto different platforms and to simulate the models on the respective platforms interacting with each other. Therefore existing models in RTDS can be leveraged in conjunction with FPGA based models. In this thesis, co-simulation is used to simulate approach several models, including RL model, switched RL model and buck converter. The models are interfaced through a Bergeron T-line interface model. Dommel's EMTP algorithm is used. Norton equivalent models of the circuits are derived, and a trapezoidal integrator is used for discretization of elements. Kirchoff's voltage (KVL) and current laws (KCL) are applied, and the equations are solved. For the FPGA simulation, a very-small time-step of 360 µs is achieved. Floating point computation is used. The results are compared with offline simulated models (MATLAB/SIMULINK) and real-time simulation models (RTDS). Further, a real hardware buck converter using Power-Pole board is designed, and the results are compared with the simulated model. In summary, this thesis presents the inclusion of an FPGA platform with RTDS system thus improving the capabilities of real-time models that can be simulated in RTDS.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-8601
Format: Thesis

Title: Design and Analysis of Segmented Sensor for Road Traffic Classification.
Creator: Golla, Prithvi Raj, Harvey, Bruce, Moses, Ren, Roberts, Rodney, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Individual vehicle information, specially, vehicle classification data play a key role in road traffic measurement. In inductive loop and piezoelectric sensor systems, traffic data such as number of axles and the distance between axles are used for vehicle classification. However, classification errors occur in distinguishing class 3 (long bed pickup truck) and class 5 (small truck) vehicles that are moving at highway speeds. In order to overcome these classification errors and improve the...
Show moreIndividual vehicle information, specially, vehicle classification data play a key role in road traffic measurement. In inductive loop and piezoelectric sensor systems, traffic data such as number of axles and the distance between axles are used for vehicle classification. However, classification errors occur in distinguishing class 3 (long bed pickup truck) and class 5 (small truck) vehicles that are moving at highway speeds. In order to overcome these classification errors and improve the durability, a new extruded polymer segmented sensor approach is developed. Segmented sensor has an additional ability to provide an estimate of the tire width to discriminate between different tire types and classify vehicles accurately. The extruded polymer conductors used in the existing prototype segmented sensor have a very high resistance that was found to limit the frequency response of the sensor. Segmented sensor with limited frequency response could not always properly identify the closed segments for vehicle moving at highway speeds. Several analysis and simulations were conducted to improve the performance of the extruded segmented sensor. In this thesis, previous efforts conducted in designing interface electronics of segmented sensor and continued efforts on designing an accurate simulation model for extruded polymer segmented sensor with its detection electronics are discussed. Contribution to the current research work on extruded segmented sensor include validating Dr. Bourner's 3x3 segmented sensor model, applying the 3x3 segmented sensor approach to existing extruded polymer segmented sensor and comparing the results with measured responses of existing 16-segmented extruded polymer sensor to develop an accurate simulation model. The cross-sectional dimensions are then increased to get an improved frequency response. Further 16-segmented extruded model is extended to a 49-segmented simulation model based on the foot print results provided by Dr. Ren Moses. Also the final model with increased cross-section is simulated to attain the required bandwidth needed to design a new prototype of extruded segmented sensor that can classify vehicles moving at highway speeds.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7395
Format: Thesis

Title: Simulating Reflectance at Interfaces Coated with Household Paints.
Creator: Prisland, Zachary, Arora, Rajendra K., Roberts, Rodney, Weatherspoon, Mark H., Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The paint and coatings industry is constantly working to improve their product, making a more efficient product at a cheaper cost. This requires some research and learning on the part of the companies, particularly in optical studies. For example, Burgess Pigment Company has developed a method, using a flash calciner, to quickly dehydrate clay, essentially popping it like popcorn, in order to add air pockets to the individual particles of clay. Clay that has undergone this process can improve...
Show moreThe paint and coatings industry is constantly working to improve their product, making a more efficient product at a cheaper cost. This requires some research and learning on the part of the companies, particularly in optical studies. For example, Burgess Pigment Company has developed a method, using a flash calciner, to quickly dehydrate clay, essentially popping it like popcorn, in order to add air pockets to the individual particles of clay. Clay that has undergone this process can improve the reflective properties of paint. The human eye, as a sensory organ, relies on reflected light in order to provide vision. As the major goal of paint is to be seen, it is easy to infer that it would be of utmost importance for the paint to reflect large amounts of light to appear more visible to the human eye and so using clay that has air pockets would be more desirable. The primary goal of this thesis will be to explore optical theory in an attempt to explain why the addition of air pockets could produce a more effective product.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7558
Format: Thesis

Title: Dynamic Interactions Between Photo Voltaic Inverters and Distribution Voltage Regulation Devices.
Creator: Ravindra, Harsha, Zheng, Jim, Steurer, Mischa, Edrington, Chris, Yu, Ming, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Increased penetration of solar PV has risen the level of concern among utilities about its potential impact on the system operation and reliability. Reverse powerflow, rise in voltage, unnecessary operations of traditional voltage regulation devices, harmonics, PV islanding, sympathy trips during feeder faults, flicker, etc. are some of the concerns mentioned in 1547.7 which deals with impact of distributed generation (like solar PV) on distribution feeders. One of the main concerns for...
Show moreIncreased penetration of solar PV has risen the level of concern among utilities about its potential impact on the system operation and reliability. Reverse powerflow, rise in voltage, unnecessary operations of traditional voltage regulation devices, harmonics, PV islanding, sympathy trips during feeder faults, flicker, etc. are some of the concerns mentioned in 1547.7 which deals with impact of distributed generation (like solar PV) on distribution feeders. One of the main concerns for utility is voltage on a feeder and its regulation. The studies conducted in this thesis go beyond the current IEEE 1547 practices, `The Standard for Interconnecting Distributed Resources with Electric Power Systems', which gives recommended practices for DG interconnection. Current standards limit PV Inverters to inject real power only and not participate in voltage regulation. But with several studies showing the benefits of using the readily available capability of inverter to inject reactive power and regulate voltage is being explored which will pave way for the new IEEE 1547 amended guidelines which would allow PV inverters to regulate voltage and supply reactive power. For this study, the PV inverters were allowed to supply reactive power and regulate voltage. In doing so, an investigation of interactions between PV inverters and traditional voltage regulation equipments like tap changing transformer (OLTC), switched capacitor bank (SCB), and step voltage regulator (SVR) were made. The study was conducted on two distinct Florida utility distribution feeders that have high penetration of PV and voltage regulation devices. One of the feeder has single large PV plant (15 MW) while the other feeder has large multiple PV plants (2.6 MW) which amounts to penetration levels of 100% and 35% respectively. Distribution feeder were modeled on an EMTP tool (RTDS) and validated against data provided by the utility. The study focuses on how different PV penetration levels and load levels on the feeder impact operation of voltage regulation devices. In doing so, the study aims at using different operating constraints for OLTC, SCB and SVR. Some candidate methods of operating constraints for OLTC, SCB and SVR are voltage, time, temperature, real power flow, reactive power flow, and combination of any methods mentioned above. As mentioned before, in going beyond the current scope of IEEE 1547, PV inverters were allowed to supply reactive power and different candidate methods currently available on inverter like constant Q, power factor, voltage based and advanced control strategies like German LV std. curve, Volt-VAR curve, Volt-pf curve were used to investigate and mitigate any possible interactions between devices. Possible best suited methods and practices were laid out incase there is an unnecessary interaction between PV inverters and OLTC, SCB and SVR for each feeder. The major observations from this study are: 1. Allowing PV inverters to regulate voltage may not necessarily increase or decrease interactions with voltage regulation devices. 2. Some of the key factors which influence interactions between voltage regulation devices and PV are feeder circuit layout (e.g. overhead line vs. cable,), voltage level, length of feeder, etc), nature of loads, location and size of loads, and location of PV. 3. Based on the cases studied within this work no common trait for defining high penetration PV circuit studies could found. 4. No correlation between PV penetration level, measured by the amount of installed PV capacity vs. feeder loading, and the severity of impact of PV on the circuit operational characteristics could be found in this study. Concluding from this work is recommended to establish a new set of metrics which truly define the impact severity of PV on distribution feeders, since the current metric of PV penetration level is clearly inadequate.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7567
Format: Thesis

Title: Utilization of Impedance Matching to Improve Damping Impedance Method-Based Phil Interface.
Creator: Paran, Sanaz, Edrington, Chris S., Foo, Simon Y., Moss, Pedro L., Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The emerging emphasis of power hardware in the loop (PHIL) as a cost effective de-risking and analysis tool has received focused attention and research from the power system/power electronic fields on this topic. Advantages of PHIL testing are safety, reduced costs, and the reliability assessment of the system. Testing and verification of the different power interfaces is an essential task when real hardware testing is desired. Using PHIL, hardware units can be interfaced with a software...
Show moreThe emerging emphasis of power hardware in the loop (PHIL) as a cost effective de-risking and analysis tool has received focused attention and research from the power system/power electronic fields on this topic. Advantages of PHIL testing are safety, reduced costs, and the reliability assessment of the system. Testing and verification of the different power interfaces is an essential task when real hardware testing is desired. Using PHIL, hardware units can be interfaced with a software-simulated environment to verify proper functionality and assess system impact. Instability during high power applications is primarily from the power interface between simulation and the hardware under test (HUT). The goal of this study is to select an optimal power interface that will allow successful operation of PHIL. While other power interfaces exist, the DIM method provides additional operational features beyond conventional interface capabilities. Additionally, the DIM method has sparked the development of PHIL due to the increased operational stability and accuracy of the system simulation. The purpose of this thesis is to demonstrate a new method of testing the stability and accuracy of the power interface in PHIL. The HIL test bed, which was developed by the Energy Conversion and Integration Thrust at the Center for Advanced Power Systems, will be used to analyze and validate the anticipated benefits of the modified DIM method. In this thesis, the dynamics of a three-phase RL load directly coupled with a three-phase inverter are simulated on a dSPACE rapid prototyping control system environment in real-time. The cascaded converters (AC/DC-DC/AC) that are used in the HIL test bed provide bi-directional capability for generating applications and a larger power rating for alternative usage. The output voltage and current at the output of the inverter will then serve as a reference for reproducing the output resistor and inductor values. Subsequently, these values are sent back to the linking impedance in the real-time model to update the resistor and inductor values. Active measurements of the real load in hardware are expected to allow implementation of the full PHIL of the real time system simulation. In addition to increased research opportunities for this field, successful PHIL system operation is expected to allow for more detailed system studies of HIL from the fundamental modeling and simulation stage to full scale testing. This thesis will introduce the ideas behind PHIL and power interface technique and explain the process and necessary steps to obtaining objectives such as stable and accurate systems. It will also demonstrate the results and verification of simulation values for different power interface methods. The final goal of this thesis is to introduce this new idea of modified DIM method, provide results and verification of simulation/testing, and show that it is in fact obtainable and can prove to be a highly useful tool in the simulation and verification of power systems.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7542
Format: Thesis

Title: Improving the Wireless Link Reliability of a Flight Termination System.
Creator: McCabe, Garrett, Brooks, Geoffrey, Harvey, Bruce, Kwan, Bing, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: A proposed alternative wireless communication technique is developed and compared to the current radio frequency command link in a Flight Termination System. The command link in a Flight Termination System requires a reliable signal in a radio frequency environment that is becoming overcrowded and is susceptible to various sources of interference. The proposed wireless command link implements direct-sequence spread spectrum modulation (DS/SS) to provide additional interference rejection. The...
Show moreA proposed alternative wireless communication technique is developed and compared to the current radio frequency command link in a Flight Termination System. The command link in a Flight Termination System requires a reliable signal in a radio frequency environment that is becoming overcrowded and is susceptible to various sources of interference. The proposed wireless command link implements direct-sequence spread spectrum modulation (DS/SS) to provide additional interference rejection. The DS/SS modulation is paired with minimum shift keying (MSK) which is a spectrally efficient constant envelope digital modulation technique. MSK also benefits from bit error rates that are competitive with other common modulation schemes such as binary phase shift keying in an additive white Gaussian noise wireless channel. The proposed MSK-SS modulation scheme is simulated alongside the current digital modulation scheme, continuous phase frequency shift keying (CPFSK), against narrowband, co-channel and multipath sources of interference to measure its effectiveness of rejecting interference. The MSK-SS system is able to provide bit error rates less than ã10ã^(-6) at 11 dB E_b/N_0, while the CPFSK system requires at least 14 dB E_b/N_0. When subjected to narrowband interference, the MSK-SS scheme benefits from 18 dB of interference rejection to CPFSK. Co-channel interference rejection of MSK-SS is observed to be 12 dB greater than CPFSK. The MSK-SS system is also able to suppress the effects of multipath interference while CPFSK error rates are extremely affected both destructively and constructively. The proposed MSK-SS modulation scheme is able to greatly improve error rates while offering interference rejection with a 99% power bandwidth less than 200 KHz and a minimal impact on the overall acquisition time. This proposed MSK-SS solution could enhance the reliability of the safety critical wireless communication link for a future generation of Flight Termination Systems.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-5398
Format: Thesis

Title: Analysis and Design of Optimally Fault Tolerant Robots.
Creator: Siddiqui, Salman A., Roberts, Rodney G., Moore, Carl A., Foo, Simon Y., Tung, Leonard J., Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Robot manipulators can be used to navigate and perform tasks in unstructured and hazardous environments where human safety is a primary concern. For example, they are used for nuclear waste disposal, space exploration, nuclear power industry, military surveillance, etc. A number of such robot manipulators are being used but the concern is that these robots should be able to complete their critical tasks in the event of failures that they encounter working in such environments. One of the most...
Show moreRobot manipulators can be used to navigate and perform tasks in unstructured and hazardous environments where human safety is a primary concern. For example, they are used for nuclear waste disposal, space exploration, nuclear power industry, military surveillance, etc. A number of such robot manipulators are being used but the concern is that these robots should be able to complete their critical tasks in the event of failures that they encounter working in such environments. One of the most common failures of field robots is an actuator failure. This type of failure affects the joints of the robots inducing failures like locked-joint failures and free-swinging joint failures. To design a fault tolerant system the robot has to rely on the incorporation of redundancy into its system. This redundancy takes several forms: sensor redundancy, analytical redundancy, and kinematic redundancy. This work focuses on using kinematic redundancy to deal with the issue of multiple locked-joint failures in the robotic systems. The goal of this work was to analyze and design fault-tolerant manipulators. The robots designed are able to finish their required task in spite of a failure in one or more of its joints. In order to design optimally fault tolerant manipulators, it is necessary to quantify fault tolerance. The approach taken here was to define fault tolerance in terms of a suitable objective function based on the robot's manipulator Jacobian. In the case of the relative manipulability index, local fault tolerance is characterized by the null space of the manipulator Jacobian. Since the null space can be used to identify locally fault tolerant manipulator configurations, one goal of this work was to develop procedures for designing fault tolerant manipulators based on obtaining a suitable null space for the manipulator Jacobian. In this work, optimally fault tolerant serial manipulators are designed that are fault tolerant to two locked-joint failures simultaneously. Furthermore, the symmetry of the manipulators is studied using positional and orientational Jacobians; and examples are presented for condition number and dynamic manipulability index to study the behavior of different fault tolerance measures. Lastly, a methodology for designing an optimally fault tolerant 4-DOF spherical wrist type mechanism was presented. It was shown that the orientational Jacobian must have a certain form for the manipulator to have the best possible relative manipulability index value. An optimal configuration along with the corresponding DH parameters was presented. Furthermore, it was pointed out that isotropic configurations of a 4-DOF spherical wrist type mechanism are fault tolerant and optimal in the sense that they have the largest possible manipulability index prior to a failure. An example of an orientational Jacobian was presented for a 6-DOF spherical wrist that is equally fault tolerant for any two joint failures.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-5433
Format: Thesis

Title: Case Study of Islanded Microgrid Control.
Creator: Mukherjee, Abhisek, Harvey, Bruce, Edrington, Chris, Roberts, Rodney, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: This paper investigates the stability issues in an islanded microgrid. A microgrid, once disconnected from the main grid, has to entirely depend on the Distributed Generators (DG), which are mostly intermittent renewable sources (e.g. PV, Wind Turbine etc.). This makes it necessary to achieve proper sharing of power, as it is not possible to supply the entire microgrid by a single source. Frequency and angle droop along with supplementary and adaptive control methods are analyzed and compared...
Show moreThis paper investigates the stability issues in an islanded microgrid. A microgrid, once disconnected from the main grid, has to entirely depend on the Distributed Generators (DG), which are mostly intermittent renewable sources (e.g. PV, Wind Turbine etc.). This makes it necessary to achieve proper sharing of power, as it is not possible to supply the entire microgrid by a single source. Frequency and angle droop along with supplementary and adaptive control methods are analyzed and compared to identify the better method for accurate load sharing. However, the conventional droop methods, which are designed for inductive microgrids, allow an error in reactive power sharing when applied in a resistive microgrid. Therefore, a secondary control is proposed for improving the accuracy of reactive power sharing. The droop method alone is not enough in situations of severe power outages, like loss of a DG unit. Use of an Energy Storage System (e.g. Battery) is proposed to serve both as a storage unit for the intermittent sources and also to prevent voltage collapse by supplying the required voltage to the load bus. In addition to that, an advanced load shedding scheme is proposed to sustain the important loads, in times of extreme power crisis. Voltage unbalance caused by harmonic distortion, due to the presence of unbalanced/non-linear loads may result in voltage collapse. A selective harmonic compensation method along with local droop controller illustrates an effective way of restoring voltage balance, even with the harmonic polluted loads connected to the network. In addition to this, the role of a programmable resistance with shunt harmonic impedance (PR-SHI) in harmonic compensation is investigated in this paper. This method is shown to allow a reduced harmonic current and achieve an accurate sharing of the harmonic compensation effort among the DG units. Lastly, a scenario of excess generation, very uncommon to the conventional grid, has been discussed in this paper. Charging of battery unit and generation of heat energy, by using Smart Loads is proposed to be the most effective way of utilizing the excess generated power. This thesis presents a unique work of bringing together different control techniques used for stability of microgrid and analyzing and comparing them in order to find the best fit for each of the possible cases in an islanded microgrid. Lastly, it recommends solutions for each case.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-5412
Format: Thesis

Title: Optimization of Microstructure of Buckypaper-Based Proton Exchange Membrane Fuel Cell by Using Electrochemical Impedance Spectroscopy.
Creator: Hagen, Mark, Zheng, Jim P., Zhu, Wei, Andrei, Petru, Foo, Simon, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The microstructure of the catalyst layer in proton exchange membrane fuel cells (PEMFCs) greatly influences the utilization of the catalyst (Pt) and the overall cell performance. Research focused on two key components in optimizing the microstructure of PEMFCs, primarily the platinum loading and Nafion loading. An electrochemical impedance spectroscopy (EIS) experiment was performed, in order to study the effects of varying these two components and come to a conclusion on the optimal amount...
Show moreThe microstructure of the catalyst layer in proton exchange membrane fuel cells (PEMFCs) greatly influences the utilization of the catalyst (Pt) and the overall cell performance. Research focused on two key components in optimizing the microstructure of PEMFCs, primarily the platinum loading and Nafion loading. An electrochemical impedance spectroscopy (EIS) experiment was performed, in order to study the effects of varying these two components and come to a conclusion on the optimal amount required to maximize cell performance of PEMFC's that are based on double-layered supported Pt (Pt/DLBP) catalyst[1].
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-5358
Format: Thesis

Title: Real-Time High Speed Generator System Emulation with Hardware-in the-Loop Application.
Creator: Stroupe, Nicholas, Edrington, Chris S., Foo, Simon Y., Li, Helen, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The emerging emphasis and benefits of distributed generation on smaller scale networks has prompted much attention and focus to research in this field. Much of the research that has grown in distributed generation has also stimulated the development of simulation software and techniques. Testing and verification of these distributed power networks is a complex task and real hardware testing is often desired. This is where simulation methods such as hardware-in-the-loop become important in...
Show moreThe emerging emphasis and benefits of distributed generation on smaller scale networks has prompted much attention and focus to research in this field. Much of the research that has grown in distributed generation has also stimulated the development of simulation software and techniques. Testing and verification of these distributed power networks is a complex task and real hardware testing is often desired. This is where simulation methods such as hardware-in-the-loop become important in which an actual hardware unit can be interfaced with a software simulated environment to verify proper functionality. In this thesis, a simulation technique is taken one step further by utilizing a hardware-in-the-loop technique to emulate the output voltage of a generator system interfaced to a scaled hardware distributed power system for testing. The purpose of this thesis is to demonstrate a new method of testing a virtually simulated generation system supplying a scaled distributed power system in hardware. This task is performed by using the Non-Linear Loads Test Bed developed by the Energy Conversion and Integration Thrust at the Center for Advanced Power Systems. This test bed consists of a series of real hardware developed converters consistent with the Navy's All-Electric-Ship proposed power system to perform various tests on controls and stability under the expected non-linear load environment of the Navy weaponry. This test bed can also explore other distributed power system research topics and serves as a flexible hardware unit for a variety of tests. In this thesis, the test bed will be utilized to perform and validate this newly developed method of generator system emulation. In this thesis, the dynamics of a high speed permanent magnet generator directly coupled with a micro turbine are virtually simulated on an FPGA in real-time. The calculated output stator voltage will then serve as a reference for a controllable three phase inverter at the input of the test bed that will emulate and reproduce these voltages on real hardware. The output of the inverter is then connected with the rest of the test bed and can consist of a variety of distributed system topologies for many testing scenarios. The idea is that the distributed power system under test in hardware can also integrate real generator system dynamics without physically involving an actual generator system. The benefits of successful generator system emulation are vast and lead to much more detailed system studies without the draw backs of needing physical generator units. Some of these advantages are safety, reduced costs, and the ability of scaling while still preserving the appropriate system dynamics. This thesis will introduce the ideas behind generator emulation and explain the process and necessary steps to obtaining such an objective. It will also demonstrate real results and verification of numerical values in real-time. The final goal of this thesis is to introduce this new idea and show that it is in fact obtainable and can prove to be a highly useful tool in the simulation and verification of distributed power systems.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-5208
Format: Thesis

Title: Usability of Command Strategies for the Phantom Omni/Schunk 5DOF Teleoperation Setup.
Creator: Peters, Brandon Allen Charles, Moore, Carl A., Roberts, Rodney G., Weatherspoon, Mark H., Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Teleoperation is the control, operation, and manipulation of a robot or other device over distance. The way in which the master controller dictates how the slave moves in its workspace is called a command strategy. Here, two command strategies are implemented for a teleoperation setup consisting of a Phantom Omni as the master controller, and a 5-DOF serial manipulator as the remote slave. The forward and inverse kinematics, the Jacobian and inverse Jacobian, for the master controller are...
Show moreTeleoperation is the control, operation, and manipulation of a robot or other device over distance. The way in which the master controller dictates how the slave moves in its workspace is called a command strategy. Here, two command strategies are implemented for a teleoperation setup consisting of a Phantom Omni as the master controller, and a 5-DOF serial manipulator as the remote slave. The forward and inverse kinematics, the Jacobian and inverse Jacobian, for the master controller are shown. The forward and inverse kinematics, and the Jacobian are developed for the serial manipulator which serves as the slave. An overview of the control program with its various components is given. The position-position command strategy and position-speed command strategy and how they are implement for the teleoperation setup is detailed. The smoothing of input values and its importance is discussed and shown in detail. The need for self-collision avoidance and ensuring the remote arm does not strike the table top is discussed, along with the algorithms that govern each type of collision avoidance. The experiment setup and results are present next, and the result are discussed. Finally, this work concludes with a discussion of future work and considerations.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-5109
Format: Thesis

Title: Multi-Rate Co-Simulation Interfaces Between the RTDS and the Opal-RT.
Creator: Rentachintala, Kavya S., Edrington, Chris S., DeBrunner, Linda S., Steurer, Michael, Foo, Simon Y., Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: ABSTRACT The aim of the thesis is to design efficient and accurate co-simulation interfaces between off-the-shelf heterogeneous real-time simulators. Co-simulation in this context refers to the distribution of subsystems of a complex power system among the different simulator platforms. The design of an efficient communication interface is the key step of the co-simulation process. The Internet is a popular option used for coupling different real-time simulator platforms. But, factors such as...
Show moreABSTRACT The aim of the thesis is to design efficient and accurate co-simulation interfaces between off-the-shelf heterogeneous real-time simulators. Co-simulation in this context refers to the distribution of subsystems of a complex power system among the different simulator platforms. The design of an efficient communication interface is the key step of the co-simulation process. The Internet is a popular option used for coupling different real-time simulator platforms. But, factors such as delay, throughput and LAN congestion are disadvantages of the internet based communication. Therefore, co-simulation interfaces that overcome the data loss during communication and that increase the computational efficiency of the simulators need to be developed. In this thesis, the two real-time electro-magnetic transient simulators used in the co-simulation are the Real-Time Digital Simulator (RTDS) and the Opal-Real-Time (Opal-RT). The work establishes analog and digital multi-rate co-simulation interfaces between these simulator platforms. The analog interface is designed using the peripheral I/O ports of the simulators and is demonstrated with the notional IPS MVDC ship model. The digital interface is established using the FPGA based reconfigurable I/O platforms of the simulators. To further analyze the co-simulation interfaces, round-trip latency and accuracy tests are conducted, and the stability of the co-simulation is investigated. From these tests, it is observed that the latency of the analog interface is decreased to 480 μs compared to 0.2 s observed when the internet is used as the communication medium. And, the results from the 11-bit parallel digital interface indicate that the design is feasible. Since it uses FPGAs for the data exchange, it overcomes the noise due to traditional A/D and D/A converters. In summary, this thesis presents a low latency analog interface and a high speed FPGA based digital interface for the real-time simulators. The importance of the co-simulation interfaces to multi-rate co-simulation techniques is studied and analyzed.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-5134
Format: Thesis

Title: Real-Time Hardware Design for Improving Laser Detection and Ranging Accuracy.
Creator: Brown, Jarrod, DeBrunner, Linda, Hughes, Clay, Brooks, Geoffrey, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Digital signal processing (DSP) algorithms for estimating target range and backscatter intensity from sampled laser detection and ranging (LADAR) systems are limited by the sampling rate of data collected and computation time requirements. An interpolating matched filter DSP algorithm is presented to improve range accuracy while maintaining a relatively low sampling rate. The algorithm interpolates sampled data and applies a matched filter with a high resolution reference waveform to recover...
Show moreDigital signal processing (DSP) algorithms for estimating target range and backscatter intensity from sampled laser detection and ranging (LADAR) systems are limited by the sampling rate of data collected and computation time requirements. An interpolating matched filter DSP algorithm is presented to improve range accuracy while maintaining a relatively low sampling rate. The algorithm interpolates sampled data and applies a matched filter with a high resolution reference waveform to recover super-sample positions of the transmitted and backscattered pulses. A custom computer architecture utilizing parallel processing is designed and synthesized on a field programmable gate array (FPGA) to optimize the DSP algorithm to operate in real-time. Research and simulation results comparing the effectiveness of different sampling rates, reference waveform models, and interpolation factors used to determine target range from LADAR data are presented. The FPGA hardware design was realized and tested with a LADAR system. A matched filter with zero padding interpolation design using a Gaussian shape reference waveform and an interpolation factor of 32 showed an 87% improvement in range accuracy over the peak detector design currently used in real-time LADAR systems.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-4743
Format: Thesis

Title: Information-Theoretic Characterization of Dynamic Energy Systems.
Creator: Bevis, Troy Lawson, Edrington, Chris S., Cartes, Dave, Foo, Simon Y., Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The latter half of the 20th century saw tremendous growth in nearly every aspect of civilization. From the internet to transportation, the various infrastructures relied upon by society has become exponentially more complex. Energy systems are no exception, and today the power grid is one of the largest infrastructures in the history of the world. The growing infrastructure has led to an increase in not only the amount of energy produced, but also an increase in the expectations of the energy...
Show moreThe latter half of the 20th century saw tremendous growth in nearly every aspect of civilization. From the internet to transportation, the various infrastructures relied upon by society has become exponentially more complex. Energy systems are no exception, and today the power grid is one of the largest infrastructures in the history of the world. The growing infrastructure has led to an increase in not only the amount of energy produced, but also an increase in the expectations of the energy systems themselves. The need for a power grid that is reliable, secure, and efficient is apparent, and there have been several initiatives to provide such a system. These increases in expectations have led to a growth in the renewable energy sources that are being integrated into the grid, a change that increases efficiency and disperses the generation throughout the system. Although this change in the grid infrastructure is beneficial, it leads to grand challenges in system level control and operation. As the number of sources increases and becomes geographically distributed, the control systems are no longer local to the system. This means that communication networks must be enhanced to support multiple devices that must communicate reliably. A common solution to these new systems is to use wide area networks for the communication network, as opposed to point-to-point communication. Although the wide area network will support a large number of devices, it generally comes with a compromise in the form of latency in the communication system. Now the device controller has latency injected into the feedback loop of the system. Also, renewable energy sources are largely non-dispatchable generation. That is, they are never guaranteed to be online and supplying the demanded energy. As renewable generation is typically modeled as stochastic process, it would useful to include this behavior in the control system algorithms. The combination of communication latency and stochastic sources are compounded by the dynamics of the grid itself. Loads are constantly changing, as well as the sources; this can sometimes lead to a quick change in system states. There is a need for a metric to be able to take into consideration all of the factors detailed above; it needs to be able to take into consideration the amount of information that is available in the system and the rate that the information is losing its value. In a dynamic system, the information is only valid for a length of time, and the controller must be able to take into account the decay of currently held information. This thesis will present the information theory metrics in a way that is useful for application to dynamic energy systems. A test case involving synchronization of several generators is presented for analysis and application of the theory. The objective is to synchronize all the generators and connect them to a common bus. As the phase shift of each generator is a random process, the effects of latency and information decay can be directly observed. The results of the experiments clearly show that the expected outcomes are observed and that entropy and information theory is a valid metric for timing requirement extraction.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-4719
Format: Thesis

Title: Torque Per Amoere Strategies in Switched Reluctance Machines at Low Speeds.
Creator: Akar, Furkan, Edrington, Chris S., Andrei, Petru, Weatherspoon, Mark H., Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: The Switched Reluctance Machine (SRM) is one of the oldest members of the electric machine family; it is known for its simple structure, ruggedness, and inexpensive manufacturability. Despite its numerous advantages, at low speeds the SRM suffers from the torque ripple which is not significant at high speeds due to the fact that it is filtered by the moment of inertia of the rotor. Therefore, its torque control at low speeds is crucial. The SRM is a highly nonlinear machine; in the case of...
Show moreThe Switched Reluctance Machine (SRM) is one of the oldest members of the electric machine family; it is known for its simple structure, ruggedness, and inexpensive manufacturability. Despite its numerous advantages, at low speeds the SRM suffers from the torque ripple which is not significant at high speeds due to the fact that it is filtered by the moment of inertia of the rotor. Therefore, its torque control at low speeds is crucial. The SRM is a highly nonlinear machine; in the case of multiphase excitation, it becomes more nonlinear due to the mutual coupling effects; ignoring these effects may cause error in anticipating the electromagnetic torque, and increase the torque ripple. In addition, the minimization of the copper losses is another important task; because high copper losses reduce the available phase voltage, decrease the service life of the battery in case it feeds the SRM. In short, the copper losses affect the efficiency of the SRM control system. Finally, it can be claimed that the objectives of an effective and efficient SRM control should be to reduce the torque ripple while considering the nonlinear characteristics of the machine as well as the mutual coupling effects, and to increase the efficiency by minimizing the copper losses. This thesis proposes a new maximum torque per ampere (MTA) strategy, which aims to reduce not only the torque ripple, but also the copper losses, for SRMs at low speeds, while mutual effects between adjacent phases are taken into consideration. The Finite Element Analysis (FEA) is conducted to obtain the electromagnetic torque and flux-linkage characteristics of a 4-phase 8/6 SRM under both single and multiphase excitation. After this step, the optimum phase current profiles are determined by the proposed method based on the Particle Swarm Optimization (PSO). This new methodology is then validated by comparing it with the conventional control method and the `balanced commutator' method, which is an efficient MTA strategy. These comparisons are realized via the static and dynamic SRM models which utilize the data retrieved from the FEA. Real hardware results are taken from another 4-phase 8/6 SRM under both the singlephase and multiphase excitations so as to derive its torque-angle characteristic. Subsequently, demanded current values for different torque levels are computed according to the conventional, `balanced commutator', and PSO methods. Finally, the PSO technique is judged against the other two methods at some selected rotor positions in terms of the torque ripple, copper losses and torque per ampere ratios.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-4685
Format: Thesis

Title: Fabrication and Evaluation of Polyvinylidene Flouride/Polyvinyl Alcohol (PVA/PVDF) Hybrid Membranes for Lithium-Air Battery Applications.
Creator: Akpanekong, Emem, Liu, Tao, Zheng, Jim P., Andrei, Petru, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: ABSTRACT A new type of hybrid hydrophobic/hydrophilic membrane is proposed in this thesis to improve the electrochemical performance of Lithium-Air battery operated with dual electrolytes. The dual electrolytes include an organic and aqueous electrolyte which is separated from one another by this solid-state hybrid polymer membrane so that they do not intermix. Also, this solid-state hybrid polymer membrane is conductive to facilitate the ionic charge carriers transport between the dual...
Show moreABSTRACT A new type of hybrid hydrophobic/hydrophilic membrane is proposed in this thesis to improve the electrochemical performance of Lithium-Air battery operated with dual electrolytes. The dual electrolytes include an organic and aqueous electrolyte which is separated from one another by this solid-state hybrid polymer membrane so that they do not intermix. Also, this solid-state hybrid polymer membrane is conductive to facilitate the ionic charge carriers transport between the dual electrolytes. With polyvinylidene fluoride (PVDF) used as a hydrophobic polymer while polyvinyl alcohol (PVA) used as the hydrophilic polymer, the hybrid membranes were prepared by phase inversion and polymer solution casting processes to test the novel concept being proposed in this study. Moreover, the ionic conductivity, electrochemical stability, permeability, and morphology of the prepared PVDF/PVA hybrid membranes have been investigated to examine their suitability for Lithium-Air battery applications. The experimental results suggest that the PVDF/PVA hydrophobic/hydrophilic hybrid membrane is stable and potentially suitable to improve the performance of Lithium-Air battery operated with dual electrolytes.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-4686
Format: Thesis

Title: Interleaved Multi-Phase Isolated Bidirectional DC-DC Converter and Its Extension.
Creator: Wang, Zhan, Li, Hui, Meyer-Baese, Anke, Foo, Simon Y., Zheng, Jim P., Andrei, Petru, Department of Electrical and Computer Engineering, Florida State University
Abstract/Description: Recently, along with the development of renewable energy technology and threat of energy shortage, hybrid electric vehicles (HEV) and DC microgrid system are increasingly attracting attentions in industry and academia. By combining internal combustion engine (ICE) and high-performance energy storage such as battery, fuel-cell and ultracapacitors, HEVs can achieve twice the fuel economy of conventional vehicles. DC microgrid is an appropriate system to interconnect dc energy sources and to...
Show moreRecently, along with the development of renewable energy technology and threat of energy shortage, hybrid electric vehicles (HEV) and DC microgrid system are increasingly attracting attentions in industry and academia. By combining internal combustion engine (ICE) and high-performance energy storage such as battery, fuel-cell and ultracapacitors, HEVs can achieve twice the fuel economy of conventional vehicles. DC microgrid is an appropriate system to interconnect dc energy sources and to supply high quality power. To enable the usage of dc energy storage, developing power converters as the power electronics interface of dc energy sources becomes imminent. Currently, the voltage type bidirectional converter is dominating topology in dc-dc applications, which is not suitable for renewable energy source with wide voltage range. Although some current type converters have been proposed, most of them are dealing with unidirectional or low power system. For a high power energy storage system, high voltage conversion ratios, high input currents and wide input voltage range are the major barriers to achieving high-efficiency power conversions. This thesis proposes a novel three-phase current-fed dual-active-bridge (DAB) dc-dc converter with transformer isolation to overcome these obstacles. The major features of the proposed converter are the following: (1) Increase converter power rating by paralleling phases; (2) Reduce the size of input dc inductors and dc link capacitor with interleaved control; (3) Achieve Zero-Voltage Switching (ZVS) over a wide load range and wide input voltage rage without auxiliary circuitry; High conversion efficiency above 94% is verified with wide input voltage range. The detailed operation analysis and experimental results to prove the proposed converter are given in chapter 3. For integrating primary sources and energy storage, this thesis also proposes an integrated three-port bidirectional dc-dc converter based on three-phase current-fed DAB converter. Comparing to the individual dc-dc converters, the major advantages of the proposed integrated three-port converter include: (1) Higher power density due to multiport and multiphase interleaved structure; (2) Easier implementation of centralized control; (3) Decoupled power management control due to natural decoupled control variables; (4) Zero voltage switching in different operation mode. Comparing to two-port dc-dc converter, there are much more operation modes for integrated three-port dc-dc converter. Based on the integrated three-port converter, a photovoltaic (PV) system with battery backup is discussed. PV panel with wide voltage variation is connected to the current-fed port and battery as an energy storage with small voltage variation is connected to the dc link. By controlling the phase shift angle, the power exchange can be controlled between low voltage side (LVS) and high voltage side (HVS). By controlling the duty cycle, the PV can realize maximum power point tracking control (MPPT). The battery as an energy buffer is charging or discharging to wipe off the gap between generated power and required power. For the grid-connected mode, it is also helpful to manage the SOC of battery. The detailed analysis, simulation and experimental verification are provided in chapter 4. Finally, the last chapter concludes the previous work and gives the scope of the future work.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-6050
Format: Thesis

Theses and Dissertations (154)	+ -
Undergraduate Honors Theses (1)	+ -

Electrical engineering (147)	+ -
Engineering (3)	+ -
Computer science (2)	+ -
Artificial intelligence (1)	+ -
Communication (1)	+ -

Mechanical engineering (1)	+ -
Robotics (1)	+ -

text (155)	+ -
doctoral thesis (3)	+ -
master thesis (2)	+ -

Florida State University (154)	+ -
Department of Electrical and Computer Engineering (151)	+ -
Foo, Simon Y. (49)	+ -
Andrei, Petru (30)	+ -
Foo, Simon (30)	+ -

Search In

Pages

Pages

Sort Results By:

Narrow results by:

Collection

Topical Subject

Genre

Type of Resource

Language

Creator

Owner