Search results

Title: Active Control of High-Speed Free Jets Using High-Frequency Excitation.
Creator: Upadhyay, Puja, Alvi, Farrukh S., Hussaini, M. Yousuff, Kumar, Rajan, Clark, Jonathan E., Gustavsson, Jonas, Florida State University, College of Engineering, Department of...
Show moreUpadhyay, Puja, Alvi, Farrukh S., Hussaini, M. Yousuff, Kumar, Rajan, Clark, Jonathan E., Gustavsson, Jonas, Florida State University, College of Engineering, Department of Mechanical Engineering
Show less
Abstract/Description: Control of aerodynamic noise generated by high-performance jet engines continues to remain a serious problem for the aviation community. Intense low frequency noise produced by large-scale coherent structures is known to dominate acoustic radiation in the aft angles. A tremendous amount of research effort has been dedicated towards the investigation of many passive and active flow control strategies to attenuate jet noise, while keeping performance penalties to a minimum. Unsteady excitation,...
Show moreControl of aerodynamic noise generated by high-performance jet engines continues to remain a serious problem for the aviation community. Intense low frequency noise produced by large-scale coherent structures is known to dominate acoustic radiation in the aft angles. A tremendous amount of research effort has been dedicated towards the investigation of many passive and active flow control strategies to attenuate jet noise, while keeping performance penalties to a minimum. Unsteady excitation, an active control technique, seeks to modify acoustic sources in the jet by leveraging the naturally-occurring flow instabilities in the shear layer. While excitation at a lower range of frequencies that scale with the dynamics of large-scale structures, has been attempted by a number of studies, effects at higher excitation frequencies remain severely unexplored. One of the major limitations stems from the lack of appropriate flow control devices that have sufficient dynamic response and/or control authority to be useful in turbulent flows, especially at higher speeds. To this end, the current study seeks to fulfill two main objectives. First, the design and characterization of two high-frequency fluidic actuators ($25$ and $60$ kHz) are undertaken, where the target frequencies are guided by the dynamics of high-speed free jets. Second, the influence of high-frequency forcing on the aeroacoustics of high-speed jets is explored in some detail by implementing the nominally 25 kHz actuator on a Mach 0.9 ($Re_D = 5\times10^5$) free jet flow field. Subsequently, these findings are directly compared to the results of steady microjet injection experiments performed in the same rig and to prior jet noise control studies, where available. Finally, limited acoustic measurements were also performed by implementing the nominally 25 kHz actuators on jets at higher Mach numbers, including shock containing jets, and elevated temperatures. Using lumped element modeling as an initial guide, the current work expands on the previous development of low-frequency (2-8 kHz) Resonance Enhanced Micro-actuators (REM) to design actuators that are capable of producing high amplitude pulses at much higher frequencies. Extensive benchtop characterization, using acoustic measurements as well as optical diagnostics using a high resolution micro-schlieren setup, is employed to characterize the flow properties and dynamic response of these actuators. The actuators produced high-amplitude output a range of frequencies, $20.3-27.8$ kHz and $54.8-78.2$ kHz, respectively. In addition to providing information on the actuator flow physics and performances at various operating conditions, the benchtop study serves to develop relatively easy-to-integrate, high-frequency actuators for active control of high-speed jets for noise reduction. Following actuator characterization studies, the nominally 25 kHz ($St_{DF} \approx 2.2$) actuators are implemented on a Mach 0.9 free jet flow field. Eight actuators are azimuthally distributed at the nozzle exit to excite the initial shear layer at frequencies that are approximately an order of magnitude higher compared to the \textit{jet preferred frequency}, $St_P \approx 0.2-0.3$. The influence of control on the mean and turbulent characteristics of the jet, especially the developing shear layer, is examined in great detail using planar and stereoscopic Particle Image Velocimetry (PIV). Examination of cross-stream velocity profiles revealed that actuation leads to strong, spatially coherent streamwise vortex pairs which in turn significantly modify the mean flow field, resulting in a prominently undulated shear layer. These vortices grow as they convect downstream, enhancing local entrainment and significantly thickening the initial shear layer. Azimuthal inhomogeneity introduced in the jet shear layer is also evident in the simultaneous redistribution and reduction of peak turbulent fluctuations in the cross-plane near the nozzle exit. Further downstream, control results in a global suppression of turbulence intensities for all axial locations, also evidenced by a longer potential core and overall reduced jet spreading. The resulting impact on the noise signature is estimated via far-field acoustic measurements. Noise reduction was observed at low to moderate frequencies for all observation angles. Direct comparison of these results with that of steady microjet injection revealed some notable differences in the initial development of streamwise vorticity and the redistribution of peak turbulence in the azimuthal direction. However, despite significant differences in the near nozzle aerodynamics, the downstream evolution of the jet appeared to approach near similar conditions with both high-frequency and steady microjet injection. Moreover, the impact on far-field noise was also comparable between the two injection methods as well as with others reported in the literature. Finally, for jets at higher Mach numbers and elevated temperatures, the effect of control was observed to vary with jet conditions. While the impact of the two control mechanisms were fairly comparable on non-shock containing jets, high-frequency forcing was observed to produce significantly larger reductions in screech and broadband shock-associated noise (BBSN) at select under-expanded jet conditions. The observed variations in control effects at different jet conditions call for further investigation.
Show less
Date Issued: 2017
Identifier: FSU_FALL2017_Upadhyay_fsu_0071E_14154
Format: Thesis

Title: Evacuating and Sheltering Aging Populations: A GIS- and Optimization-Based Methodology.
Creator: Kocatepe, Ayberk, Ozguven, Eren Erman, Brown, Jeff R., Moses, Ren, Sobanjo, John Olusegun, Florida State University, College of Engineering, Department of Civil and...
Show moreKocatepe, Ayberk, Ozguven, Eren Erman, Brown, Jeff R., Moses, Ren, Sobanjo, John Olusegun, Florida State University, College of Engineering, Department of Civil and Environmental Engineering
Show less
Abstract/Description: Evacuating individuals and allocating space in shelters are complex tasks that depend on disaster characteristics, roadway network characteristics, the demographics and socioeconomic status of people in the affected region, as well as the effectiveness of the emergency plans. This problem becomes even more challenging when special needs (access and functional needs) populations and those with pets are considered since they may require more time in the event of an evacuation along with more...
Show moreEvacuating individuals and allocating space in shelters are complex tasks that depend on disaster characteristics, roadway network characteristics, the demographics and socioeconomic status of people in the affected region, as well as the effectiveness of the emergency plans. This problem becomes even more challenging when special needs (access and functional needs) populations and those with pets are considered since they may require more time in the event of an evacuation along with more space in shelters. Satisfying the needs of aging victims during emergency evacuations is critical and requires extra attention in the presence of highly uncertain disaster conditions. During Irma, it was very hard to manage the evacuation of aging people who had disabilities and mobility restrictions, did have special needs or pets. This study develops a Geographical Information Systems (GIS)-based methodology to measure and assess the transportation accessibility of these critical facilities through a diverse set of case study applications in the State of Florida. This research presents a timely evaluation and assessment of aging-focused evacuations towards providing better decision support during emergency transportation operations. This analysis is applied on a case study application set in Florida with a focus on the delays, evacuation travel times and critical bottlenecks, which can be vital for aging victims’ safety and survival. This study also emphasizes the use of GIS-based maps and modeling scenarios in support of emergency evacuation operations, in order to both satisfy the needs of aging people and account for real-world disruptions such as road closures. Additionally, a variety of scenarios are constructed to simulate evacuating 65+ and 85+ populations living in the evacuation zone, providing dynamic congested travel times. Finally, a capacitated p-median optimization model is implemented to maximize the accessibility and capacity of the existing shelters for 85+ populations with special needs (access and functional needs) or pets. Results indicate that the location and allocations of people to shelters are sensitive to demographics and roadway conditions, and the accessibility to shelters can be improved for this group of people based on optimization model results. A contribution of the research will be the evaluation of emergency evacuation performance of the transportation network under multiple disaster scenarios and the detailed modeling of key transportation facilities where special needs would take place. By exploring the use of multi-layered approach for emergency operations, this research will also increase the performance in evacuating aging people who has limitations.
Show less
Date Issued: 2017
Identifier: FSU_FALL2017_Kocatepe_fsu_0071E_14253
Format: Thesis

Title: Hirschman Transform Applications in Compressive Sensing.
Creator: Xi, Peng, DeBrunner, Victor E., Gallivan, Kyle A., Harvey, Bruce A., DeBrunner, Linda S., Roberts, Rodney G., Florida State University, College of Engineering, Department of...
Show moreXi, Peng, DeBrunner, Victor E., Gallivan, Kyle A., Harvey, Bruce A., DeBrunner, Linda S., Roberts, Rodney G., Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: The CS technology has attracted considerable attention because it can surpass the traditional limit of Nyquist sampling theory. Rather than sampling a signal at a high frequency and then compressing it, the CS senses the target signal in a compressed format directly. However, the great sampling improvement results in the increased complexity in decoding. The optimization of sensing structure never stops to simplify the decoding procedure as much as possible. Unlike the Heisenberg-Weyl measure...
Show moreThe CS technology has attracted considerable attention because it can surpass the traditional limit of Nyquist sampling theory. Rather than sampling a signal at a high frequency and then compressing it, the CS senses the target signal in a compressed format directly. However, the great sampling improvement results in the increased complexity in decoding. The optimization of sensing structure never stops to simplify the decoding procedure as much as possible. Unlike the Heisenberg-Weyl measure, the Hirschman notion of joint uncertainty is based on entropy rather than energy. The Discrete Hirschman Transform (DHT) has been proved to be superior in complexity reduction and high resolution to the traditional Discrete Fourier Transform in many aspects such as fast filtering, spectrum estimation, and image identification. In this dissertation, I implement a new deterministic compressive sensing system based on DHT with four contributions: (1) apply Weyl's sum character estimation to the DHT matrices to develop a new deterministic sensing structure (2) theoretically prove that the new sensing structure satisfy the Mutual Incoherence Property (3) discover a Non-tensor Wavelet Transform as the sparse basis for DHT sensing structures as well as for other DFT and DFT-like sensing matrices. (4) design a DHT computational core based on FPGA and related communication suite based on C#.
Show less
Date Issued: 2017
Identifier: FSU_FALL2017_XI_fsu_0071E_14193
Format: Thesis

Title: Ultrafast Laser Machining of Dielectrics: A Sharp Interface Model.
Creator: Woerner, Peter Christopher, Oates, William, Lin, Shangchao, Guo, Wei, Florida State University, College of Engineering, Department of Mechanical Engineering
Abstract/Description: High temperature pressure sensing is desirable for a broad range of applications related to re-entry of space vehicles and control of combustion processes; however, limited materials can sustain temperatures above 1000C while under time-varying pressure. A sapphire based optical pressure transducer has been proposed for measuring pressure at temperatures approaching 1600C. Manufacturing such sensors has focused on picosecond laser machining. Current research has produced models which can...
Show moreHigh temperature pressure sensing is desirable for a broad range of applications related to re-entry of space vehicles and control of combustion processes; however, limited materials can sustain temperatures above 1000C while under time-varying pressure. A sapphire based optical pressure transducer has been proposed for measuring pressure at temperatures approaching 1600C. Manufacturing such sensors has focused on picosecond laser machining. Current research has produced models which can predict ablation depth for longer (ns) pulses and shorter (fs) pulses but there is an underwhelming amount of research focusing on predicting and understanding the mechanics of picosecond pulses. This is partially because of transitions in the mode of ablation processes associated with photothermal versus photochemical behavior. We put forth a general model for laser ablation using Maxwell's equations and a sharp interface equation and compare different constitutive laws which couple the two equations together. The proposed modeling results are compared to laser machining experimental data on sapphire from the literature to illustrate key material parameter uncertainty and sensitivity to the laser machining process. Bayesian uncertainty quantification is used to help validate the approximations within the constitutive equations.
Show less
Date Issued: 2016
Identifier: FSU_FALL2017_Woerner_fsu_0071N_13473
Format: Thesis

Title: Designing Time Efficient Real Time Hardware in the Loop Simulation Using Input Profile Temporal Compression.
Creator: Chatterjee, Sourindu, Faruque, Md Omar, Steurer, Mischa, Li, Hui, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Abstract/Description: The modern day smart grid technology relies heavily on data acquisition and analysis. A distributed controller governs smart microgrid functions with one or more renewable sources and smart controllable loads. This sort of intelligent, scalable system is the primary drive for the Energy Internet (EI). Hence, in modern-day power systems engineering to analyze, understand and make efficient system design choices that capture robustness and scalability, Hardware in the Loop (HIL) simulations are...
Show moreThe modern day smart grid technology relies heavily on data acquisition and analysis. A distributed controller governs smart microgrid functions with one or more renewable sources and smart controllable loads. This sort of intelligent, scalable system is the primary drive for the Energy Internet (EI). Hence, in modern-day power systems engineering to analyze, understand and make efficient system design choices that capture robustness and scalability, Hardware in the Loop (HIL) simulations are required. Real-Time Simulations (RTS) is the state of the art technology thrusting the capstone of innovation for this industry. As engineers, we can model, simulate and validate smart grids operations more rapidly, robustly and reliably using RTS. With enough smaller time step for the simulation, the boundary between the real and the simulated systems slowly vanishes. It also enables the system to be simulated as Controller Hardware in the Loop (CHIL) or Power Hardware in the Loop (PHIL) setups, evolving and imitating the real physical world. The HIL (Hardware in the Loop) setup also enables a real data source or sink to be in the system to form the loop of exchange between the simulated system and real-world hardware which is most often a control hardware. The implementation of such a setup is made possible at Center for Advanced Power Systems (CAPS), named as Hardware in the Loop Test-Bed (HIL-TB). This evaluation architecture provides a systematic solution to HIL simulations. Now the sampling time for real-world sensors is generally in the order of microseconds, enabling this collected data to emulate the cyber-physical domain accurately. Thus, the challenge previously was to address the throughput of real-world input data into the simulated system efficiently and correctly. The quality of the Design of Simulation (DoS) using the real world data in the form of Real Time Input Profile (RTIP), improves, affects the quality of response of the real-time cyber-physical system simulation. Thus great care needs to be taken to prepare, prune and project the RTIPs to improve and enhance the system performance evaluation index. To solve this problem, partially successful attempts have been made in the direction of machine learning by using methods like clustering and regression to characterize large input profiles or by breaking them into subsections using fixed length sliding window techniques. These classic methods then perform data analysis on those sub-pieces to distinguish among a variety of input profiles and assign an index. These sub-profiles or sections would be then loaded into the simulation as environmental input to represent the physical system in the HIL simulations. This traditional procedure is observed to be arbitrary because clustering algorithms and metrics for methods like regression or classification are user-defined and there exists no standard practice to deal with huge input profiles. There have also been confusions regarding the size of the sliding window to create subsections, subsection joining logic, etc. Thus, to address this issue, the primary focus of this study is to present a systematic, controlled, reliable procedure to explore, screen, crop large input profiles and then to compress the same by selecting sections with most relative importance using a modified version of “knapsack” dynamic programming algorithm. This compression primarily aims to shrink down the total simulation time without much loss of information. The latter part of this study focuses towards response driven performance evaluation of the HIL simulations. This is ensured by targeted compression of original input profile based on the certain requirement of the simulation. This approach ensures that the control algorithm (CHIL simulations) or any other system operator is driven in a specific direction in the simulation response space by effectively sampling the input parameters space. The fully automated HIL-TB evaluation framework aided with Input Profile Time Compression (IPTC) module delivers a fast-convergent validation for the performance evaluation with relatively similar system response. In this study, the IPTC module has been applied to seven load profiles to compress their temporal length by a third. The case study used for the simulation with these RTIPs is the Future Renewable Electric Energy Delivery and Management (FREEDM) IEEE seven node system. The test results show great coherence between the uncompressed and compressed response and validate the performance of the IPTC module applied to real-world HIL simulations. Thus, it can conclude that the functionality of the IPTC module is validated by the quality of simulation response gained out of the compressed simulation as compared to uncompressed simulation. In future, endeavors can be made in this path by expanding the functionality of this compression module to not only identifying and managing important sections based on some initial assumption about the objective of the control application but also providing cognitive, autonomous understanding of the behavior of the controls and using that knowledge accomplishing compression of large input profiles.
Show less
Date Issued: 2017
Identifier: FSU_FALL2017_CHATTERJEE_fsu_0071N_14274
Format: Thesis

Title: Global Stability Analysis and Control of Compressible Flows over Rectangular Cavities.
Creator: Sun, Yiyang, Taira, Kunihiko, Yu, Weikuan, Cattafesta, Louis N., Ukeiley, Lawrence S., Lin, Shangchao, Florida State University, College of Engineering, Department of Mechanical...
Show moreSun, Yiyang, Taira, Kunihiko, Yu, Weikuan, Cattafesta, Louis N., Ukeiley, Lawrence S., Lin, Shangchao, Florida State University, College of Engineering, Department of Mechanical Engineering
Show less
Abstract/Description: The present numerical investigation aims to uncover the inherent instability in compressible cavity flows and aid designs of effective flow control to alter undesirable flow features. Two-dimensional (2D) and three-dimensional (3D) global stabilities of compressible open-cavity flows are examined in detail, which provides insights into designs of active flow control to reduce the pressure fluctuations over the cavity. The stability characteristics of compressible spanwise-periodic open-cavity...
Show moreThe present numerical investigation aims to uncover the inherent instability in compressible cavity flows and aid designs of effective flow control to alter undesirable flow features. Two-dimensional (2D) and three-dimensional (3D) global stabilities of compressible open-cavity flows are examined in detail, which provides insights into designs of active flow control to reduce the pressure fluctuations over the cavity. The stability characteristics of compressible spanwise-periodic open-cavity flows are investigated with direct numerical simulation (DNS) and biglobal stability analysis for rectangular cavities with length-to-depth ratios of $L/D=2$ and 6. This study examines the behavior of instabilities with respect to stable and unstable steady states in the laminar regimes for subsonic as well as transonic conditions where compressibility plays an important role. It is observed that an increase in Mach number destabilizes the flow in the subsonic regime and stabilizes the flow in the transonic regime. Biglobal stability analysis for spanwise-periodic flows over rectangular cavities with large aspect ratio is closely examined in this study due to its importance in aerodynamic applications. Moreover, biglobal stability analysis is conducted to extract 2D and 3D eigenmodes for prescribed spanwise wavelengths $\lambda/D$ about the 2D steady state. The properties of 2D eigenmodes agree well with those observed in the 2D DNS. In the analysis of 3D eigenmodes, it is found that an increase of Mach number stabilizes dominant 3D eigenmodes. For a short cavity with $L/D=2$, the 3D eigenmodes primarily stem from centrifugal instabilities. For a long cavity with $L/D=6$, other types of eigenmodes appear whose structures extend from the aft-region to the mid-region of the cavity, in addition to the centrifugal stability mode located in the rear part of the cavity. A selected number of 3D DNS are performed at $M_\infty=0.6$ for cavities with $L/D=2$ and 6. For $L/D=2$, the properties of 3D structures present in the 3D nonlinear flow correspond closely to those obtained from linear stability analysis. However, for $L/D=6$, the 3D eigenmodes cannot be clearly observed in the 3D DNS, due to the strong nonlinearity that develops over the length of the cavity. In addition, it is noted that three-dimensionality in the flow helps alleviate violent oscillations for the long cavity. The analysis performed in this paper can provide valuable insights for designing effective flow control strategies to suppress undesirable aerodynamic and pressure fluctuations in compressible open-cavity flows. Three-dimensional nonlinear simulations (DNS and LES) are also conducted to examine influence of cavity width, sidewall boundary conditions, free stream Mach numbers, and Reynolds numbers on open-cavity flows. DNS and large eddy simulations (LES) are performed with $L/D=6$, width-to-depth ratios of $W/D$=1 and 2 for Reynolds number of $Re_D = 502$ and $10^4$. To numerically study the effects of cavity width on the flows, we consider (1) 2D cavities with spanwise periodicity and (2) finite-span cavities with no-slip adiabatic walls. Furthermore, the analyses are conducted for subsonic ($M_\infty=0.6$) and supersonic ($M_\infty=1.4$) speeds to reveal compressibility effects. It is found that, at low $Re_D=502$, widening the cavity can decrease the velocity fluctuations of the flow by introducing spanwise variations in the shear layer to reduce the kinetic energy from spanwise vortices associated with Rossiter modes. Both velocity and pressure fluctuations decrease in the finite-span cavity compared to those with spanwise periodic boundary conditions. With the characteristics of base flows revealed, flow control is implemented for turbulent cavity flows where steady blowing is introduced along the leading edge of the cavity for both subsonic ($M_\infty=0.6$) and supersonic ($M_\infty=1.4$) flows. We examine how the actuations interact with the flows and reduce the velocity and pressure fluctuations with and without sidewalls. From the control study, we find that pressure reduction on the cavity surfaces can be achieved in an effective manner by taking advantage of 3D flow physics.
Show less
Date Issued: 2017
Identifier: FSU_FALL2017_Sun_fsu_0071E_14244
Format: Thesis

Title: Small Signal Instability Assessment and Mitigation in Power Electronics Based Power Systems.
Creator: Ye, Qing, Li, Hui, Collins, E. (Emmanuel), Steurer, Mischa, Yu, Ming, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Abstract/Description: Power electronics technology has been widely used in electric power system to achieve high energy efficiency and high renewable energy penetration. Small signal instability phenomena could easily occur in systems with abundant power electronics because of high order passive elements and controller interactions among power converters. These instability issues degrade power quality or even cause system failure. Therefore it is necessary to build accurate small signal models for stability...
Show morePower electronics technology has been widely used in electric power system to achieve high energy efficiency and high renewable energy penetration. Small signal instability phenomena could easily occur in systems with abundant power electronics because of high order passive elements and controller interactions among power converters. These instability issues degrade power quality or even cause system failure. Therefore it is necessary to build accurate small signal models for stability analysis and develop effective resonance mitigation techniques for stability improvement. The general stability analysis methods including eigenvalues-based method, component connection method, passivity-based method and impedance-based method have been evaluated and summarized. The impedance-based method is selected as the stability analysis tool for this research due to its advantages compared to other methods. Besides, three popular resonance suppression techniques, i.e. passive damper, active damper and virtual impedance control, are also studied and evaluated. The virtual impedance control is of interest because it does not reduce system efficiency or reliability compared to both the passive and active damper. A unified impedance-based stability criterion (UIBSC) has been proposed for paralleled grid-tied inverters. Compared to the traditional IBSC which evaluates all minor loop gains (MLGs) of individual inverter, the UIBSC assesses the derived global minor loop gain (GMLG) only once to determine system stability. As a result, the computation efforts can be significantly reduced when system contains a large number of inverters. In addition, a stability-oriented design guideline has been derived for the paralleled grid-tied inverters based on the GMLG. By using the guideline, the grid impedance, inverter filter parameters, time delays of digital control and control parameters can be analyzed or designed to meet the system stability requirement. The small signal stability of the FREEDM system is a critical issue due to the abundant power electronics devices and flexible control strategies. The impedance modeling methods for current controlled inverters, inverter stage of the SST, DAB converters are developed. The influences of control schemes on power converter terminal behaviors are analyzed as well. Stability criteria for several types of grid enabled by the SST are derived. The bidirectional power flow effect is also considered. These instability phenomena are demonstrated in ac, dc, and hybrid ac/dc grids of FREEDM system using HIL test bed. Finally, the conclusions are given and the scope of future work is discussed.
Show less
Date Issued: 2017
Identifier: FSU_FALL2017_Ye_fsu_0071E_14130
Format: Thesis

Title: Three Dimensional Control of High-Speed Cavity Flow Oscillations.
Creator: Zhang, Yang, Cattafesta, Louis N., Tam, Christopher K. W., Taira, Kunihiko, Collins, E. (Emmanuel), Florida State University, College of Engineering, Department of Mechanical...
Show moreZhang, Yang, Cattafesta, Louis N., Tam, Christopher K. W., Taira, Kunihiko, Collins, E. (Emmanuel), Florida State University, College of Engineering, Department of Mechanical Engineering
Show less
Abstract/Description: Cavity structures, like weapons bays and landing gear wells on aircraft, suffer from severe oscillations under high speed flow conditions. These oscillations are associated with intense surface pressure/velocity fluctuations inside the cavity which can radiate strong acoustic waves and cause structural damage. The physics of cavity flows have been studied for several decades with much of the effort put towards flow controls to reduce these oscillations. Geometric modifications of the cavity...
Show moreCavity structures, like weapons bays and landing gear wells on aircraft, suffer from severe oscillations under high speed flow conditions. These oscillations are associated with intense surface pressure/velocity fluctuations inside the cavity which can radiate strong acoustic waves and cause structural damage. The physics of cavity flows have been studied for several decades with much of the effort put towards flow controls to reduce these oscillations. Geometric modifications of the cavity structure are usually only effective for suppressing the oscillations within the designed flow conditions. Therefore, active flow control is more attractive for a wider application range. Previous research have proven that mass/momentum injection at the cavity leading edge can effectively suppress the pressure/velocity fluctuations. Due to the limited control authorities of current actuators, a steady actuation which introduces three-dimensional disturbances is studied to reduce the energy requirements of the actuator and improve the suppression of the oscillations over a wide range of free-stream Mach numbers. Surface fluctuating pressure measurements are acquired to determine the control performances of a number of 3-D actuation configurations. Flow fields, including velocity fields and density gradient fields, are measured to reveal the flow features with and without the flow control. Mathematical methods, including modal decomposition analysis, are further applied to study the dynamics of the flow field. All of these analyses together elucidate the effective 3-D actuation mechanism in the cavity flow control. The suppression of pressure fluctuations are obtained in both full-span and finite-span cavities. The successful flow control is found to be the redistribution of the energy in the shear layer by the counter-rotating-vortex pairs, which are introduced by the 3-D actuation in the cross-flow. In addition, a design guide for the actuator geometry is given based on the observations.
Show less
Date Issued: 2017
Identifier: FSU_FALL2017_ZHANG_fsu_0071E_14127
Format: Thesis

Title: Optimization of Groundwater Long-Term Monitoring Network Optimization of Groundwater Long-Term Monitoring Network with Ant Colony Optimization with Ant Colony Optimization.
Creator: Liu, Xiaoli, Chen, Gang, Ye, Ming, Wang, Xiaoqiang, Hilton, Amy B. Chan, Huang, Wenrui, Tang, Youneng, Florida State University, College of Engineering, Department of Civil and...
Show moreLiu, Xiaoli, Chen, Gang, Ye, Ming, Wang, Xiaoqiang, Hilton, Amy B. Chan, Huang, Wenrui, Tang, Youneng, Florida State University, College of Engineering, Department of Civil and Environmental Engineering
Show less
Abstract/Description: Groundwater remediation is conducted in polluted sites to remove contaminants and to restore ground water quality. After remediation goals are achieved, long-term groundwater monitoring (LTM) that can span decades is required to assess the concentration of residual contaminants and to avoid the risk of human health and environment. On large remediation sites, the cost for maintaining a LTM network, collecting samples, conducting water quality lab analysis can be a significant, persistent and...
Show moreGroundwater remediation is conducted in polluted sites to remove contaminants and to restore ground water quality. After remediation goals are achieved, long-term groundwater monitoring (LTM) that can span decades is required to assess the concentration of residual contaminants and to avoid the risk of human health and environment. On large remediation sites, the cost for maintaining a LTM network, collecting samples, conducting water quality lab analysis can be a significant, persistent and growing financial burden for the private entities and government agencies who are responsible for environmental remediation projects. LTM network optimization offers an opportunity to improve the cost-effectiveness of the LTM effort while meeting data accuracy requirements. The optimization includes identifying the redundancy in the monitoring network, and recommending changes to protect against potential impacts to the public and the environment. This study develops a variant ant colony optimization (VACO) method, using ordinary kriging (OK) or inverse distance weighting (IDW) for data interpolation, to identify optimal LTM networks that minimize the cost of LTM by reducing the number of monitoring locations with minimum overall data loss. ACO is a global stochastic search method inspired by the collective problem-solving ability of a colony of ants as they search for the most efficient routes from their nests to food sources. The performance of ACO variant (VACO) developed in this study is evaluated separately in two test cases. In the first case, VACO is used to solve a simplified traveling sales person problem. In the second case, both enumeration method and VACO are employed for optimization of a synthetic long term monitoring network of 73 wells generated from a groundwater transport simulation model. The two sets of test show that the VACO performs well for optimization problems. The VACO is finally adopted for the optimization of a long term monitoring network of 30 wells in Logistic Center, Washington, with the data interpolation methods of inverse distance weighing, ordinary kriging, and modified inverse distance weighing which is developed in this study. The optimization results are analyzed and group of ideal redundant wells identified. The conclusion of this study is summarized at the end, and future work is suggested.
Show less
Date Issued: 2017
Identifier: FSU_FALL2017_Liu_fsu_0071E_14254
Format: Thesis

Title: Analysis of Optimization Processses for Solid State Fabrication of Olivine Cathode Materials.
Creator: Oladimeji, Charles, Moss, Pedro L., Weatherspoon, Mark H., Andrei, Petru, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Abstract/Description: Lithium ion battery discovered since the 1980s has become pivotal to our energy needs. With the need for a shift to renewable energy and increased use of portable devices, energy storage has become a very important aspect of modern day life and technology. In the thesis, optimization techniques for solid state calcination of lithium olivine batteries are characterized and analyzed. A brief introduction into lithium ion battery is discussed, the chemistry and physics of the materials is...
Show moreLithium ion battery discovered since the 1980s has become pivotal to our energy needs. With the need for a shift to renewable energy and increased use of portable devices, energy storage has become a very important aspect of modern day life and technology. In the thesis, optimization techniques for solid state calcination of lithium olivine batteries are characterized and analyzed. A brief introduction into lithium ion battery is discussed, the chemistry and physics of the materials is studied in details. Emphasis is placed on the olivine structure, industrially utilized synthesis method and the performance of olivine lithium ion batteries are also discussed in details. Olivine structure LiFePO₄ (LFP) was synthesized via solid state processes, using Li₂CO₃, NH₄H₂PO₄ and FeC₂O₄·H₂O and C₁₂H₂₂O₁₁ as precursor materials. The effects of calendaring in terms of charge/discharge capacity, cycle life performance, surface morphology, and ac impedance was analyzed. The resulting LFP electrode was divided in part, Part A was left as is and Part B was calendared. The calendared electrode exhibited lower impedance under electrochemical impedance test. The calendared electrode also exhibited a higher discharge capacity of about 130 mAh/g at 0.1C compared to the as-is electrode with discharge capacity of about 120mAh/g. Olivine structure LiMnPO₄ (LMP) was also synthesized via solid state processes, using Li₂CO₃, NH₄H₂PO₄, MnCO₃ and C₁₂H₂₂O₁₁ as precursor materials. Comparison of the carbon addition process was done by adding sucrose to the initial precursor mix and carbon black at the later stages of fabrication. The 3 step carbon addition exhibited the highest specific capacity of about 72mAh/g, 1 step carbon addition possessed the least capacity of about 45mAh/g, while the 2 step process had a capacity of about 65mA/g.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Oladimeji_fsu_0071N_12821
Format: Thesis

Title: Piezoresistivity of Mechanically Drawn Swcnt Thin Films: Mechanism and Optimizing Principle.
Creator: Obitayo, Waris, Liu, Tao, Shanbhag, Sachin, Zhang, Mei, Okoli, Okenwa, Oates, William S., Florida State University, College of Engineering, Department of Industrial and...
Show moreObitayo, Waris, Liu, Tao, Shanbhag, Sachin, Zhang, Mei, Okoli, Okenwa, Oates, William S., Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Carbon nanotubes (CNTs) are known to exhibit outstanding mechanical, electrical, thermal, and coupled electromechanical properties. CNTs can be employed towards the design of an innovative strain sensor with enhanced multifunctionality due to their load carrying capability, sensing properties, high thermal stability, and outstanding electrical conductivity. All these features indicate the prospect to use CNTs in a very wide range of applications, for instance, highly sensitive resistance-type...
Show moreCarbon nanotubes (CNTs) are known to exhibit outstanding mechanical, electrical, thermal, and coupled electromechanical properties. CNTs can be employed towards the design of an innovative strain sensor with enhanced multifunctionality due to their load carrying capability, sensing properties, high thermal stability, and outstanding electrical conductivity. All these features indicate the prospect to use CNTs in a very wide range of applications, for instance, highly sensitive resistance-type strain/force sensors, wearable electronics, flexible microelectronic devices, robotic skins, and in-situ structural health monitoring. CNT-based strain sensors can be divided into two different types, the individual CNT- based strain sensors and the ensemble CNT-based strain sensors e.g. CNT/polymer nanocomposites and CNT thin films. In contrast, to individual CNT-based strain sensors with very high gauge factor (GF) e.g. ~3000, the ensemble CNT-based strain sensors exhibit very low GFs e.g. for a SWCNT thin film strain sensor, GF is ~1. This research discusses the mechanisms and the optimizing principles of a SWCNT thin film piezoresistive sensor, and provide an experimental validation of the numerical/analytical investigations. The dependence of the piezoresistivity on key parameters like alignment, network density, bundle diameter (effective tunneling area), and SWCNT length is studied. The tunneling effect is significant in SWCNT thin films showing higher degrees of alignment, due to greater inter-tube distances between the SWCNTs as compared to random oriented SWCNT thin films. It can be concluded that SWCNT thin films featuring higher alignment would have a higher GF. On the other hand, the use of sparse network density which comprises of aligned SWCNTs can as well intensify the tunneling effect which can result to a further increase in the GF. In addition, it is well-known that percolation is greatly influenced by the geometry of the nanotubes e.g. bundle diameter and length. A study on the influence of bundle diameter of SWCNTs on the piezoresistivity behavior of mechanically drawn SWCNT thin films showed the best performance with an improved GF of ~10 when compared to the randomly oriented SWCNT thin films with GF of ~1. The non-linear piezoresistivity of the mechanically drawn SWCNT thin films is considered to be the main mechanism behind the high strain sensitivity. Furthermore, information about the average length and length distribution is very essential when examining the influence of individual nanotube length on the strain sensitivity. With that in mind, we use our previously developed preparative ultracentrifuge method (PUM), and our newly developed gel electrophoresis and simultaneous Raman and photolumiscence spectroscopy (GEP-SRSPL) to characterize the average length and length distribution of SWCNTs respectively.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Obitayo_fsu_0071E_12891
Format: Thesis

Title: Aging Population-Focused Transportation Accessibility Assessment of Critical Facilities in Florida.
Creator: Ozel, Hidayet, Ozguven, Eren Erman, Moses, Ren, Sobanjo, John Olusegun, Florida State University, College of Engineering, Department of Civil and Environmental Engineering
Abstract/Description: A significant responsibility of officials involved in transportation planning is ensuring people's accessibility to critical facilities such as multi-modal terminals and emergency shelters. This challenging task depends on the available transportation infrastructure as well as the overall population, traffic, roadway and regional characteristics. Such planning takes on additional complexity when aging populations are considered because any extra time they incur reaching these facilities can...
Show moreA significant responsibility of officials involved in transportation planning is ensuring people's accessibility to critical facilities such as multi-modal terminals and emergency shelters. This challenging task depends on the available transportation infrastructure as well as the overall population, traffic, roadway and regional characteristics. Such planning takes on additional complexity when aging populations are considered because any extra time they incur reaching these facilities can be especially confounding in light of their potential health and other safety concerns. As such, there is a need for state/federal transportation plans to have a transportation assessment component that specifically focuses on the accessibility of aging people ('the aging population' can be thought of as those people aged 65+ in this study) to critical facilities. To accomplish this goal, this study first describes a Geographical Information Systems (GIS)-based methodology for measuring the aging population-focused accessibility to multi-modal facilities in Florida. Spatially detailed population block- and county-based accessibility scores are calculated with respect to key intermodal facility types (airports, bus stations, and railway and ferry stations), and visually assessed via GIS maps. Second, a spatial optimization model is presented which focuses on maximizing the accessibility of aging populations to the emergency shelters. For this purpose, a p-median optimization model is proposed in order to minimize the transportation cost (travel time or roadway network distance costs between the origins –centroids of population blocks- and destinations –emergency shelters) in the transportation network, and therefore providing maximum accessibility for aging adults to the emergency shelters. In this context, different transportation costs are used: (a) roadway network distance, (b) free flow travel time, and (c) congested travel time. This model is also extended towards a capacitated p-median model with hubs, which makes it possible to conduct an extensive evaluation of possible intermediate hub locations that can have a significant effect on the accessibility of those shelters. The knowledge obtained from this accessibility analysis can successfully contribute to the development of more reliable aging population-focused transportation plans, as the analysis points to specific areas where accessibility could be improved as well as those candidate locations that can be serve as additional emergency shelters and intermediate hubs.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Ozel_fsu_0071N_12963
Format: Thesis

Title: Effect of Friction on Vehicle Crashworthiness during Rollover.
Creator: Gleba, Michal, Jung, Sungmoon, Rambo-Roddenberry, Michelle Deanna, Spainhour, Lisa, Wekezer, Jerry W., Florida State University, College of Engineering, Department of Civil and...
Show moreGleba, Michal, Jung, Sungmoon, Rambo-Roddenberry, Michelle Deanna, Spainhour, Lisa, Wekezer, Jerry W., Florida State University, College of Engineering, Department of Civil and Environmental Engineering
Show less
Abstract/Description: The State of Florida acquires over 300 cutaway buses every year. The increasing popularity of such buses raised concerns about passenger safety and overall crashworthiness of this transportation mode. Dimensions of the cutaway buses and their two-stage manufacturing process made them exempted from safety standards which were developed for smaller passenger cars as well as for large coaches. To fill this gap, cutaway bus manufacturers try to demonstrate the strength of their bus roof...
Show moreThe State of Florida acquires over 300 cutaway buses every year. The increasing popularity of such buses raised concerns about passenger safety and overall crashworthiness of this transportation mode. Dimensions of the cutaway buses and their two-stage manufacturing process made them exempted from safety standards which were developed for smaller passenger cars as well as for large coaches. To fill this gap, cutaway bus manufacturers try to demonstrate the strength of their bus roof structures by using FMVSS 220 standard, which follows conservative quasi-static load tests for school buses in the US. However, more advanced, dynamic based safety standard - Regulation 66, was developed in Europe. It is based on a dynamic rollover test which more closely resembles an actual rollover accident. A cutaway bus is placed on a tilt table 800 mm above a concrete slab. The bus is tilted until it falls and impacts the concrete deck and the deformation of the sidewalls is measured in order to check if there is any intrusion into a so called 'survival space'. This standard was endorsed by 44 countries through the United Nation resolution. However, the Regulation 66 standard does not specify all the parameters regarding the rollover test. From multiple tests it can be observed that the friction between the vehicle and the concrete slab which is being impacted by the bus has an influence on the outcomes of the experiment and has great contribution to either a positive or negative assessment of the crashworthiness of a tested vehicle. This Master thesis focuses on the friction parameters between the impacting cutaway bus and a concrete slab used in the Regulation 66 standard. Due to dynamic nature of the experiment, the impact of the bus exerts a high normal force on the concrete slab. Together with an uneven and non-standard geometry of the elements in contact with the concrete deck the standard coefficient of friction found in the literature or obtained using standard tests may not hold. The proper assessment of this coefficient is important since many rollover tests are carried out numerically using Finite Element Methods. The use of numerical analysis reduces the cost of an expensive full scale rollover test. However, it requires verified and validated parameters in order to consider the results trustworthy. The experimental part of this thesis consists of designing and carrying out experiments to evaluate the coefficient of friction for an impacting cutaway bus and a concrete slab. The results from the experiments are incorporated into an explicit computer code LS-DYNA, which is used for numerical analysis of the cutaway buses. The final outcome of this thesis will be validating the coefficient of friction used in the Finite Element Analysis which will lead to improvement of the Finite Element models and will be used to check the influence of the coefficient of friction on vehicle structure deformation (Deformation Index) during rollover accidents.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Gleba_fsu_0071N_12953
Format: Thesis

Title: Modeling, Simulation, and Experimental Verification of Impedance Spectra in Li-Air Batteries.
Creator: Mehta, Mohit Rakesh, Andrei, Petru, Schlenoff, Joseph B., Zheng, Jianping P., Moss, Pedro L., Li, Hui, Florida State University, College of Engineering, Department of Electrical...
Show moreMehta, Mohit Rakesh, Andrei, Petru, Schlenoff, Joseph B., Zheng, Jianping P., Moss, Pedro L., Li, Hui, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: There has been a growing interest in electrochemical storage devices such as batteries, fuel cells and supercapacitors in recent years. This interest is due to our increasing dependence on portable electronic devices and on the high demand for energy storage from the electric transport vehicles and electrical power grid industries. As we transition towards cleaner renewable fuel sources such as solar, wind, tidal, etc. our dependence on energy storage devices will continue to grow. Li-air...
Show moreThere has been a growing interest in electrochemical storage devices such as batteries, fuel cells and supercapacitors in recent years. This interest is due to our increasing dependence on portable electronic devices and on the high demand for energy storage from the electric transport vehicles and electrical power grid industries. As we transition towards cleaner renewable fuel sources such as solar, wind, tidal, etc. our dependence on energy storage devices will continue to grow. Li-air offers much higher energy density than all other batteries based on electrochemical storage. However, these batteries currently suffer from a number of issues such as a low cyclability and a reduced practical energy density compared to the theoretical energy density. The deposition of lithium peroxide on the surface of the cathode is one of the main causes for the low practical specific capacity of lithium-air batteries with organic electrolyte. Electrochemical impedance spectroscopy (EIS) has been used in the past to extract physical parameters such as chemical diffusion coefficient, effective diffusion coefficient, Faradaic reaction rate, degradation and stability of an electrochemical device. In this dissertation, a physics based analytical model is developed to study the EIS of Li-air batteries, in which the mass transport inside the cathode is limited by oxygen diffusion, during charge and discharge. The model takes into consideration the effects of double layer, Faradaic processes, and oxygen diffusion in the cathode, but neglects the effects of anode, separator, conductivity of the deposit layer, and Li-ion transport. The analytical model predicts that the effects of Faradaic impedance can be hidden by the double layer capacitance. Therefore, the dissertation focuses separately on two cases: 1) the case when the Faradaic process and the double layer capacitance are separate and can be observed as two different semicircles on the Nyquist plot and 2) the case when the Faradaic process is shadowed by the double layer capacitance and shows up as only one large semicircle on the Nyquist plot. A simple expression is developed to extract physical parameters such as the values of the diffusion coefficient of oxygen and Faradaic reaction rate from experimental impedance spectrum for each of the two cases. The diffusion coefficient can be determined by using the resistances (real impedance intercept on the Nyquist plot) of both the semicircles for the first case and by using the combined resistance for the second case. Once, the effective oxygen diffusion coefficient is estimated, it can be used to estimate the value of the reaction constant. This method of extracting the values of the diffusion coefficient and reaction constant can serve as a tool in identifying an effective electrolyte or cathode material. It can also serve as a noninvasive technique to identify and also quantify the use of the catalyst to improve the reaction kinetics in an electrochemical system. Finally, finite element simulations are used to validate the analytical models and to study the effects of discharge products on the impedance spectra of Li-air batteries with organic electrolyte. The finite element simulations are based on the theory of concentrated solutions and the complex impedance spectra are computed by linearizing the partial differential equations that describe the mass and charge transport in Li-air batteries. These equations include the oxygen diffusion equation, the Li drift-diffusion equation, and the electron conduction equation. The reaction at the anode and cathode are described by Butler-Volmer kinetics. The total impedance of a Li-air battery increases by more than 200% when the response is measured near the end of the discharge cycle as compared to on a fresh battery. The resistivity of the deposition layer significantly affects the deposition profile and the total impedance. Using electrolytes with high oxygen solubility and concentrated O2 gas at high pressures will reduce the total impedance of Li-air batteries.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Mehta_fsu_0071E_12827
Format: Thesis

Title: Coupled Subspace Analysis and PCA Variants: A Computer Vision Application.
Creator: Nelson, Richard A., Roberts, Rodney G., Foo, Simon Y., Tung, Leonard J., Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Abstract/Description: In numerous applications involving high dimensional data, certain subspace techniques such as principal components analysis (PCA) may be utilized in feature extraction. Often, PCA can reduce the dimensionality while retaining most of the significant information of the original data. This can be beneficial not only for representation of the data more compactly (compression), but also for transforming the data into a more useful form for applications involving feature extraction and...
Show moreIn numerous applications involving high dimensional data, certain subspace techniques such as principal components analysis (PCA) may be utilized in feature extraction. Often, PCA can reduce the dimensionality while retaining most of the significant information of the original data. This can be beneficial not only for representation of the data more compactly (compression), but also for transforming the data into a more useful form for applications involving feature extraction and classification. Relatively recent developments with PCA extend conventional principal components analysis to newer variants of PCA which appear particularly useful in computer vision and image applications: (1) two dimensional PCA ("2D PCA"), and (2) bidirectional or bilateral two dimensional PCA ("B2DPCA", "Bi2DPCA", or "(2D)² PCA"). The latter category includes an iterative version which is an example of coupled subspace analysis or "CSA"; the non-iterative version is known as projective Bi2DPCA. In this thesis, these PCA variants are considered as special cases of the more general CSA. Theoretical advantages of 2D PCA and bidirectional PCA over conventional PCA should arise from the fact that significant information about the spatial relationship between image pixels may be discarded in conventional PCA as the image is represented by a large column vector, whereas 2D PCA and bidirectional PCA techniques can preserve more of this information by representing the image as a matrix rather than a long vector. The problems of small sample size, and curse of dimensionality are also alleviated to some extent, particularly in the cases of B2DPCA and iterated CSA. Some of these PCA variants have been proposed in various image recognition applications recently, including biometric identification using iris texture, face images, and palm prints, and categorization of wood species based on wood grain texture to name a few examples. So, while much focus has been placed on feature extraction methods such as use of Gabor wavelets or similar techniques for some applications such as iris recognition, some subspace techniques, including some of these PCA variants, have shown promise in conjunction with image preprocessing techniques for removal of uneven background illumination and contrast enhancement. In this thesis, the image application of biometric iris recognition is chosen as the means of evaluating potential advantages of these newer PCA variants, including CSA, in the context of feature extraction and classification. The rich texture information of these images, and the utilization of effective image registration techniques, yields images which are well suited for this purpose. As the primary focus of this thesis, these PCA variants are evalulated using closed set identification test mode, and are compared using Euclidean distance single nearest neighbor classifier; images are preprocessed using top-hat filtering and contrast limiting adaptive histogram equalization (CLAHE). Use of multiple test (probe) images is considered, and the impact on performance is considered also for training image sets with 2, 3, and 4 sample images per class. Concurrently, the application of iris image recognition is addressed in detail. Other applications for which these PCA variants and preprocessing techniques may be beneficial are discussed in the concluding section.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Nelson_fsu_0071N_12964
Format: Thesis

Title: Scalable Carbon Nanotube (CNT) Alignment: Process Development, Alignment Mechanisms and CNT/Carbon Fiber Hybrid Composite Applications.
Creator: Downes, Rebekah, Liang, Zhiyong (Richard), Vanli, Omer Arda, Spainhour, Lisa, Okoli, Okenwa, Maskell, Robin, Florida State University, College of Engineering, Department of...
Show moreDownes, Rebekah, Liang, Zhiyong (Richard), Vanli, Omer Arda, Spainhour, Lisa, Okoli, Okenwa, Maskell, Robin, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: To transfer the incredible properties, including ultrahigh tensile strength, Young's modulus, and electrical conductivity of an individual carbon nanotube (CNT) into composite applications, the constituent nanotubes need to possess adequate alignment, interfacial bonding and a high CNT volume fraction. Direct incorporation of the CNT films, or buckypaper, materials into carbon fiber laminated structures to manufacture hybrid composites is an effective approach to utilize the lightweight,...
Show moreTo transfer the incredible properties, including ultrahigh tensile strength, Young's modulus, and electrical conductivity of an individual carbon nanotube (CNT) into composite applications, the constituent nanotubes need to possess adequate alignment, interfacial bonding and a high CNT volume fraction. Direct incorporation of the CNT films, or buckypaper, materials into carbon fiber laminated structures to manufacture hybrid composites is an effective approach to utilize the lightweight, conductive and nanostructured nature of dense CNT networks for multifunctional applications of structural carbon fiber composites. This work studied the microstructure-property relationships of CNT networks when orientation is induced. The mechanical stretching method is shown to be scalable and effective for ultra-high alignment. A manufacturing technique of applying a viscous resin treatment before the stretching procedure is shown to allow up to 80% stretching strain and a resultant alignment fraction of 0.93. The resin acts as an effective load transfer media to substantially enhance the ductility for high stretching strain. The alignment characterization is carried out through Raman spectroscopy and X-ray diffraction methods that reveal the graphitic crystal structure of the film. The load transfer mechanisms and failure modes of aligned CNT composites are explored through high concentration CNT reinforced nanocomposites. Atomic resolution transmission electron microscopy (TEM) analysis reveals unusual CNT crystal packing and permit the observation of interesting structural features of the CNTs and their assemblages, including collapse, flattened packing, preferred stacking, folding and twisting phenomena, as well as CNT pullouts from bundles and the resin matrix. The intimate surface-to-surface contact areas between aligned and flattened nanotubes, driven by van der Waals interactions, give rise to a high density packing of the flattened CNTs in the nanocomposite, resembling a graphitic crystal material. Molecular dynamics (MD) simulations were performed through collaboration to model the packing structure and understand the dependence of density on the relative content of flattened nanotube and void space. Macroscopic modeling predictions illustrate how the alignment and volume fraction of the encompassed CNTs affect the stiffness of the overall composite. CNT thin films were integrated into carbon fiber (CF) prepreg composites to create hybrid composite materials with high CNT content through industry standard autoclave fabrication processing. Resin bleeding along the through-thickness direction was inhibited due to extra-low permeability, nano/micro dual-scale flow characteristics and high resin absorbing capacity of the CNT thin film in hybrid composites. CNT swelling effects and resin starvation phenomena are studied in relation to the amount and orientation of the CNT laminates. The flexural three-point bending results of the random and aligned CNT/CF hybrids exhibit an increased resistance to catastrophic failure even under repeated loading parameters as compared to the CF control samples. The dramatic improvements in both in-plane and through-thickness electrical conductivities demonstrate potential for both structural and multifunctional applications of the resultant hybrid composites.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Downes_fsu_0071E_12844
Format: Thesis

Title: Image Segmentation for Extracting Nanoparticles.
Creator: Allada, Kartheek, Park, Chiwoo, Shrivastava, Abhishek Kumar, Liu, Tao, Barbu, Adrian G. (Adrian Gheorghe), Florida State University, College of Engineering, Department of...
Show moreAllada, Kartheek, Park, Chiwoo, Shrivastava, Abhishek Kumar, Liu, Tao, Barbu, Adrian G. (Adrian Gheorghe), Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: With the advent of nanotechnology, nanomaterials have drastically improved our lives in a very short span of time. The more we can tap into this resource, the more we can change our lives for better. All the applications of nanomaterials depend on how well we can synthesize the nanoparticles in accordance with our desired shape and size, as they determine the properties and thereby the functionality of the nanomaterials. Therefore in this report, it is focused on how to extract the shape of...
Show moreWith the advent of nanotechnology, nanomaterials have drastically improved our lives in a very short span of time. The more we can tap into this resource, the more we can change our lives for better. All the applications of nanomaterials depend on how well we can synthesize the nanoparticles in accordance with our desired shape and size, as they determine the properties and thereby the functionality of the nanomaterials. Therefore in this report, it is focused on how to extract the shape of the nanoparticles from electron microscope images using image segmentation more accurately and more efficiently. By developing automated image segmentation procedure, we can systematically determine the contours of an assortment of nanoparticles from electron microscope images; reducing data examination and interpretation time substantially. As a result, the defects in the nanomaterials can be reduced drastically by providing an automated update to the parameters controlling the production of nanomaterials. The report proposes new image segmentation techniques that specifically work very effectively in extracting nanoparticles from electron microscope images. These techniques are manifested by imparting new features to Sliding Band Filter (SBF) method called Gradient Band Filter (GBF) and by amalgamating GBF with Active Contour Without Edges method, followed by fine tuning of μ (a positive parameter in Mumford-Shah functional). The incremental improvement in the performance (in terms of computation time, accuracy and false positives) of extracting nanoparticles is therefore portrayed by comparing image segmentation by SBF versus GBF, followed by comparing Active Contour Without Edges versus Active Contour Without Edges with the fusion of Gradient Band Filter (ACGBF). In addition we compare the performance of a new technique called Variance Method to fine tune the value of μ with fine tuning of μ based on ground truth, followed by gauging the improvement in the performance of image segmentation by ACGBF with fine tuned value of μ over ACGBF with an arbitrary value of μ.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Allada_fsu_0071N_12975
Format: Thesis

Title: Characterization of Sapphire: for Its Material Properties at High Temperatures.
Creator: Bal, Harman Singh, Oates, William S., Kumar, Rajan, Hellstrom, Eric, Florida State University, College of Engineering, Department of Mechanical Engineering
Abstract/Description: There are numerous needs for sensing, one of which is in pressure sensing for high temperature application such as combustion related process and embedded in aircraft wings for reusable space vehicles. Currently, silicon based MEMS technology is used for pressure sensing. However, due to material properties the sensors have a limited range of approximately 600°C which is capable of being pushed towards 1000°C with active cooling. This can introduce reliability issues when you add more parts...
Show moreThere are numerous needs for sensing, one of which is in pressure sensing for high temperature application such as combustion related process and embedded in aircraft wings for reusable space vehicles. Currently, silicon based MEMS technology is used for pressure sensing. However, due to material properties the sensors have a limited range of approximately 600°C which is capable of being pushed towards 1000°C with active cooling. This can introduce reliability issues when you add more parts and high flow rates to remove large amounts of heat. To overcome this challenge, sapphire is investigated for optical based pressure transducers at temperatures approaching 1400°C. Due to its hardness and chemical inertness, traditional cutting and etching methods used in MEMS technology are not applicable. A method that is being investigated as a possible alternative is laser machining using a picosecond laser. In this research, we study the material property changes that occur from laser machining and quantify the changes with the experimental results obtained by testing sapphire at high-temperature with a standard 4-point bending set-up. Keywords: Sapphire, Bayesian analysis, thermomechanics, alumina
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Bal_fsu_0071N_12982
Format: Thesis

Title: Alternative Measurement Approach Using Inverse Scattering Theory to Improve Modeling of Rotating Machines in Ungrounded Shipboard Power Systems.
Creator: Breslend, Patrick Ryan, Edrington, Christopher S., Graber, Lukas, Steurer, Michael, Florida State University, College of Engineering, Department of Electrical and Computer...
Show moreBreslend, Patrick Ryan, Edrington, Christopher S., Graber, Lukas, Steurer, Michael, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: The Navy has proposed to use a shipboard power system operating at medium voltage direct current to distribute power for their all-electric ship. The power is generated by electric machines as alternating current and requires power electronic rectifiers to output direct current. Power electronics converters are needed to convert the direct current to alternating current for ship propulsion and service loads. An increase in the use of fast switching power electronics is expected in future...
Show moreThe Navy has proposed to use a shipboard power system operating at medium voltage direct current to distribute power for their all-electric ship. The power is generated by electric machines as alternating current and requires power electronic rectifiers to output direct current. Power electronics converters are needed to convert the direct current to alternating current for ship propulsion and service loads. An increase in the use of fast switching power electronics is expected in future ships. The increased voltage rise time on switches is known to produce unwanted high frequencies with corresponding wavelengths of the same order of magnitude as the length of the ship hull. These high frequency transients can cause the ship system to couple with the surrounding ship hull causing adverse effects. The amount of high frequency content and the impact it has on the ship system performance is difficult to calculate with current models. Increased voltage and performance requirements for power electronics has led to advancements in switching frequencies into the 10s to 100s of kilohertz and increased voltage edge rates. The faster switching corresponds to higher frequency responses from the shipboard power system. Research has shown that high frequency content in electrical power systems is responsible for parasitic coupling and ultimately damage to the equipment. Electric machines, for instance, have increased winding and iron losses, overvoltages at the terminals, and even bearing currents via shaft voltages. The Navy is interested in simulating ship systems to test their electromagnetic compatibility before implementing or committing to a specific design. There are numerous techniques used to acquire machine parameters that have been proven to be useful in modeling electric machine behavior. The approaches were considered by the amount of proprietary information needed to acquire accurate results, the complexity of the modeling methods, and the overall time it takes for implementation. A majority of system simulations gravitate towards simple solutions for machine behavior which require assumptions to be made that deviate from the actual machine behavior. Exact inner dimensions, winding layouts, end winding dimensions, insulation thickness, and other information are proprietary and often not accurate representations of the physical machine once built. It is time consuming to obtain an accurate working model when assumptions are made or when detailed computer aided design models are needed to calculate machine response quantities. The research modeling approach put forth in this paper is not aimed at capturing the steady-state behavior of the machine. It is shown that a detailed understanding of the motor may not be necessary to accurately model the high frequency effects. It is the transient behavior at non-operating frequencies that need to be modeled correctly to develop new models of shipboard power systems for grounding research. The frequency dependent information is most useful to determine frequencies of interest that other modeling techniques are less likely to capture and point out. Previously suggested measurement techniques have been considered useful in determining parameters of machines but are not always accurately implemented without in-depth knowledge of the motor that may be proprietary. Lumped-parameter models are based on extracting information at transitional frequencies or looking at the slope of a variable over a frequency range. These models tend to be over simplified representations of the component by averaging the parameters for given ranges. In reality a machine's impedance varies with all frequencies. Lumped parameter based models typically over simplify the grounding behavior of the machine by not varying the impedance as a function of frequency. The technique used in this research is based on scattering parameters, a way of determining the terminal behavior of the machine without the knowledge of the actual inner workings of the machine. The inverse scattering technique uses steady-state stimuli to calculate reflection and transmission coefficients of system components allowing the device to be considered as a black box. This can be understood as electrical snapshots of how the machine would respond when subjected to a range of spectral content. The approach could have a significant impact on the modeling of ground interactions with machines. The machine can now be measured and characterized with no prior knowledge of the machine. The measurements are placed in simulation software in the typical measurement configurations used in other approaches to extract parametric data. It was discovered that these different configuration setups could now be measured in software without the need to physically reconfigure the machine's wiring for each measurement. This modeling approach was coined 'virtual measurement modeling.' To the best of the author's knowledge there are not any known techniques for fast model prototyping of electric machines which cover a broad range of frequencies with high accuracy. This thesis will present a possible solution for consideration in future models developed for grounding studies. This approach outlines a promising technique that can be easily implemented with high accuracy and reproducibility. The technique was derived from inverse scattering theory and was implemented on electric machines for characterizing high frequency behaviors.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Breslend_fsu_0071N_12834
Format: Thesis

Title: A Statistical Analysis of Effects of Test Methods on Spun Carbon Nanotube Yarn.
Creator: Veliky, Kenneth Blake, Liang, Zhiyong Richard, Zhang, Mei, Vanli, Omer Arda, Florida State University, College of Engineering, Department of Industrial and Manufacturing...
Show moreVeliky, Kenneth Blake, Liang, Zhiyong Richard, Zhang, Mei, Vanli, Omer Arda, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Carbon nanotube (CNT) fibers are very promising materials for many applications. Strong interactions among individual CNTs could produce a dense yarn results in exceptional properties. These properties are used in the application of high-performance reinforcement for composites. As the reinforcement, the primary function is to provide outstanding load bearing capability. Currently literatures use a variety of measurement techniques and gauge lengths that have not been uniform for CNT yarn...
Show moreCarbon nanotube (CNT) fibers are very promising materials for many applications. Strong interactions among individual CNTs could produce a dense yarn results in exceptional properties. These properties are used in the application of high-performance reinforcement for composites. As the reinforcement, the primary function is to provide outstanding load bearing capability. Currently literatures use a variety of measurement techniques and gauge lengths that have not been uniform for CNT yarn tests. The need for a standardized testing method for characterization is necessary in generating reproducible and comparable data for CNT yarn or fiber materials. In this work, the strength of CNT fibers was characterized using three different types of tensile test method: the film and fiber test fixtures from dynamics mechanic analysis (DMA), and TS 600 tensile fixture. Samples that underwent the film and TS 600 tensile fixture were attached with a thick paper tabbing methodology based on ASTM standard D3379. As for the fiber fixture was performed with the test material attached directly to the fixture based on the fiber test instruction from TA Instrument. The results of the three different methods provided distinct variance in stress, strain, and modulus. A design of experiment (DoE) was established and performed on the DMA film fixture as determined from the preliminary experiment. The DoE was successful in quantifying the critical parameters' ranges that attributed to standard deviation of average stress. These parameters were then tested on 30 more samples with an improved additive manufactured tab. The results significantly decreased all mechanical testing parameters' standard deviations. Most importantly, the results prove the probability of a valid gauge break increased to more than 400%.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Veliky_fsu_0071N_12979
Format: Thesis

Title: Uncertainty Analysis of Multifunctional Constitutive Relations and Adaptive Structures.
Creator: Miles, Paul R., Oates, William, Hussaini, M. Yousuff, Zeng, Changchun (Chad), Taira, Kunihiko, Lin, Shangchao, Smith, Ralph C., Florida State University, College of Engineering,...
Show moreMiles, Paul R., Oates, William, Hussaini, M. Yousuff, Zeng, Changchun (Chad), Taira, Kunihiko, Lin, Shangchao, Smith, Ralph C., Florida State University, College of Engineering, Department of Mechanical Engineering
Show less
Abstract/Description: Practically all engineering applications require knowledge of uncertainty. Accurately quantifying uncertainty within engineering problems supports model development, potentially leading to identification of key risk factors or cost reductions. Often the full problem requires modeling behavior of materials or structures from the quantum scale all the way up to the macroscopic scale. Predicting such behavior can be extremely complex, and uncertainty in modeling is often increased due to...
Show morePractically all engineering applications require knowledge of uncertainty. Accurately quantifying uncertainty within engineering problems supports model development, potentially leading to identification of key risk factors or cost reductions. Often the full problem requires modeling behavior of materials or structures from the quantum scale all the way up to the macroscopic scale. Predicting such behavior can be extremely complex, and uncertainty in modeling is often increased due to necessary assumptions. We plan to demonstrate the benefits of performing uncertainty analysis on engineering problems, specifically in the development of constitutive relations and structural analysis of smart materials and adaptive structures. This will be highlighted by a discussion of ferroelectric materials and their domain structure interaction, as well as dielectric elastomers’ viscoelastic and electrostrictive properties.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Miles_fsu_0071E_14033
Format: Thesis

Title: Driver Behavior in Mixed Connected-Automated and Conventional Vehicle Traffic at a Freeway Merge.
Creator: Chityala, Sneha, Sobanjo, John Olusegun, Ozguven, Eren Erman, Spainhour, Lisa, Florida State University, College of Engineering, Department of Civil and Environmental Engineering
Abstract/Description: Wireless communication through automated and connected vehicles is an evolving technology. This ameliorates the driving conditions, reduces time spent in traffic and curtails the crash occurrences. One of the most challenging areas, where these interactions can be most useful, are freeway merge ramps. Both the drivers on mainline and the drivers merging would be skeptical about their decisions at this location. The drivers who want to merge to the freeway mainline would seek to find an...
Show moreWireless communication through automated and connected vehicles is an evolving technology. This ameliorates the driving conditions, reduces time spent in traffic and curtails the crash occurrences. One of the most challenging areas, where these interactions can be most useful, are freeway merge ramps. Both the drivers on mainline and the drivers merging would be skeptical about their decisions at this location. The drivers who want to merge to the freeway mainline would seek to find an appropriate gap to enter the mainline of the freeway. While the technology of connected and automated vehicles is being promoted, the reality now is that for the foreseeable future, the traffic would not comprise 100% of such connected and automated vehicles. In other words, there will be a mixed traffic of manually-driven and connected/automated vehicles, with various levels of automation in the latter types of vehicles. Capturing the driver behavior at the merge locations into a freeway with such mixed traffic, will be useful in learning and improving safety on the roadways. The Driving Simulator is a useful device in capturing driver behaviors. In this study scenarios are developed in the Driving Simulator which allows mixed traffic on mainline and also observe the driver behaviors from the ramp onto the merge. Overall there were three variations in the mixed traffic flow for the mainline freeway: 0%, 50% and 75% penetration rates. The freeway traffic was generated for the mixed traffic by first developing a mixed probability distribution which assumes exponential distributions for the inter-arrival times of manually-driven vehicles and a constant headway (uniform distribution) is assumed between connected vehicles. The mixed distribution was then used to randomly generate vehicles through Monte Carlo simulation, with assigned headways in the Driving Simulator for the various connected vehicle penetration rates. The subject driver’s speed along the ramp is monitored, as well as the speeds of those vehicles on the freeway. The gaps between freeway vehicles, which were accepted by the subject driver, were recorded for the various situations and scenarios. There were a total of 41 participants, with 29 young drivers (younger than 65 years) and 12 elderly drivers (65 years and older, amongst which 2 were between 55 and 65 years old). Three scenarios were presented to the drivers. The first driving task was to determine headway gap acceptance for the three penetration rates, based on the perception of the subject drivers (without driving). The second test involved the subjects actually driving on the ramp and implementing a suitable gap to merge on the freeway traffic at each ramp. From the data collected, the critical gaps were estimated based on perception. The gaps accepted while driving were also tabulated analyzed. It was observed that the critical gap for the young drivers in 0%, 50%, 75% penetrations rate are 2.9 sec, 1.8 sec, and 1.7 sec respectively. The critical gaps observed for elderly drivers aged over 65 are 3.5 sec, 2.0 sec, and 1.9 sec respectively. Based on an Analysis of Variance (ANOVA), there is no evidence to prove the equality of means for different groups classified by age, gender and driving experience in both perception and actual driving conditions for 0% and 50% penetration rates. It was observed that the headway gaps accepted by young and drivers, both by perception and driving in 0% penetration rate were 2.39 sec and 2.35 sec respectively. The headway gaps accepted by elderly drivers both by perception and driving in 0% penetration rate were 2.4 sec and 2.72 sec respectively. When the ANOVA was performed between the 0% and 50% penetration rates of driving conditions, it was observed that there is a lot of variation in the mean headway gaps accepted. The values of average headway gaps accepted for young drivers were estimated as 2.36 sec and 1.53 sec respectively, in the 0% and 50% penetration rates. For the elderly drivers the average headway gap values observed were 2.72 sec and 1.55 sec respectively, in the 0% and 50% penetration rates traffic. The results also indicated the subject driver acceleration and deceleration behavior at the merge ramp. The results also showed that when the (aggressive) drivers accelerated to match the velocity of mainline traffic and merged in between connected-automated vehicles with the shortest gap, effects were noticed on the mainline traffic, where the main line traffic had to decelerate rapidly. Overall, it was observed that the subject drivers accepted shorter headway gaps as the penetration rates increases.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Chityala_fsu_0071N_14121
Format: Thesis

Title: Development of a Simple Microfluidic Device for Characterizing Chemotaxis of Macrophage in Response to Myelin Basic Protein.
Creator: Jia, Xiaolin, Chung, Hoyong, Mohammadigoushki, Hadi, Florida State University, College of Engineering, Department of Chemical and Biomedical Engineering
Abstract/Description: Microfluidic devices are widely used for cell-based analysis. There are always needs to develop simpler, more effective and/or less costly devices than the existing ones for this application. A simple microfluidic device has been fabricated and tested for studying chemotaxis of macrophages in this study. The device was made of polydimethylsiloxane bound to a cell culture dish. It consisted of a millimeter-sized cavum and two arrays of straight channels of 5 um in width and 6um height and...
Show moreMicrofluidic devices are widely used for cell-based analysis. There are always needs to develop simpler, more effective and/or less costly devices than the existing ones for this application. A simple microfluidic device has been fabricated and tested for studying chemotaxis of macrophages in this study. The device was made of polydimethylsiloxane bound to a cell culture dish. It consisted of a millimeter-sized cavum and two arrays of straight channels of 5 um in width and 6um height and about two millimeters in length. The channels connected the cavum, in which a chemoattractant was loaded, with the surrounding environment, in which the macrophages were cultured. The device was first tested with a known chemoattractant - fetal bovine serum and the chemoattractive property of myelin basic protein (MBP) was then studied using the device. The macrophages were found to migrate towards to the MBP-loaded cavum in larger quantity and greater distance than those in the control samples. The results prove the usefulness of the microfluidic device for chemotaxis assay and indicate that MBP is a chemoattractant for the macrophages.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Jia_fsu_0071N_13978
Format: Thesis

Title: Experimental Characterization of Photoresponsive Azobenzene Polymers.
Creator: Chowdhury, Sadiyah Sabah, Oates, William, Lin, Shangchao, Ordóñez, Juan Carlos, Florida State University, College of Engineering, Department of Mechanical Engineering
Abstract/Description: Azobenzene is a photo responsive polymer which undergoes molecular change under exposure to certain wavelengths of light. This molecular shape change can cause an overall macroscopic shape change in an azobenzene polymer network. This promising photostrictive behavior has broad range of applications in flow control, robotics and energy harvesting applications. The conversion of solar energy directly into mechanical work provides unique capabilities in adaptive structures. In this thesis,...
Show moreAzobenzene is a photo responsive polymer which undergoes molecular change under exposure to certain wavelengths of light. This molecular shape change can cause an overall macroscopic shape change in an azobenzene polymer network. This promising photostrictive behavior has broad range of applications in flow control, robotics and energy harvesting applications. The conversion of solar energy directly into mechanical work provides unique capabilities in adaptive structures. In this thesis, stress measurements show that irradiated azo-LCN experience photochemical and thermomechanical stress. Experimental results show that stress response depends highly on the range of pre-stress applied and the threshold pre-stress differs for different polarization directions.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Chowdhury_fsu_0071N_13891
Format: Thesis

Title: Low Voltage Ride-through for Photovoltaic Systems Using Finite Control-Set Model Predictive Control.
Creator: Franco, Fernand Diaz, Edrington, Christopher S., Ordóñez, Juan Carlos, Faruque, Md Omar (Professor of Electrical and Computer Engineering), Foo, Simon Y., Florida State...
Show moreFranco, Fernand Diaz, Edrington, Christopher S., Ordóñez, Juan Carlos, Faruque, Md Omar (Professor of Electrical and Computer Engineering), Foo, Simon Y., Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: Grid codes impose immunity requirements to the generation systems that are connected to the transmission lines. Immunity refers to the generator’s capability to overcome grid abnormal conditions. One of the requirements is to remain connected during a certain time when a fault, like voltage sag, is presented. During the fault scenario, a generator unit should remain connected for a pre-determined amount of time, and also provide reactive power to support the grid voltage. This is called low...
Show moreGrid codes impose immunity requirements to the generation systems that are connected to the transmission lines. Immunity refers to the generator’s capability to overcome grid abnormal conditions. One of the requirements is to remain connected during a certain time when a fault, like voltage sag, is presented. During the fault scenario, a generator unit should remain connected for a pre-determined amount of time, and also provide reactive power to support the grid voltage. This is called low-voltage ride through (LVRT). Initially, LVRT requirements were imposed for large generator units like wind farms connected to the transmission network; however, due to the increased penetration of distributed generation (DG) on the distribution system, new grid codes extend the mentioned capability to generator units connected to the distribution grid. Due to matured photovoltaic (PV) technology and the decreased price of PV panels, PV grid tied installations are proliferating in the utility grids; this is creating new challenges related to voltage control. In the past, DG such as PV were allowed to trip from the grid when a fault or unbalance occurred and reconnect within several seconds (sometimes minutes) once the fault had been cleared. Nevertheless, thanks to high PV penetration nowadays, the same method cannot be used because it will further deteriorate the power quality and potentially end in a power blackout. Different approaches have been considered to fulfill the LVRT requirement on PV systems. A large amount of literature focuses on the control of the grid side converter of the PV installation rather than the control of PV operation during the fault, and most control designs applied to the grid side follow classical control methods. Moreover, the effects of the grid fault on the generator side impose a challenge for controlling the PV systems since the quality of the synthesized converter voltages and currents depends on the dc link power/voltage control. This document proposes a Model based Predictive Control (MPC) for controlling a two stage PV system to fulfill LVRT requirements. MPC offers important advantages over traditional linear control strategies since the MPC cost function can include constraints that are difficult to achieve in classical control. Special attention is given to implementation of the proposed control algorithms. Simplified MPC algorithms that do not compromise the converter performance and immunity requirement are discussed.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_DiazFranco_fsu_0071E_14045
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: Manipulation of Potential Energy Surfaces of Binuclear Platinum Complexes and Their Application as Viscosity Sensor.
Creator: Zhou, Chenkun, Ma, Biwu, Hallinan, Daniel T., Ramakrishnan, Subramanian, Florida State University, College of Engineering, Department of Chemical and Biomedical Engineering
Abstract/Description: Photoinduced structural change (PSC) is a fundamental excited-state dynamic process in chemical and biological systems, e.g. photoinduced flattening distortion of Cu(II) complexes1, PSCs of binuclear Pt (II) complexes2, 3. This process is highly dependent on the configuration of molecular excited-state potential energy surfaces (PESs). However, due to the lack of guidelines and approaches for designing excited-state PESs, precise manipulation of PSC processes is still very challenging. In...
Show morePhotoinduced structural change (PSC) is a fundamental excited-state dynamic process in chemical and biological systems, e.g. photoinduced flattening distortion of Cu(II) complexes1, PSCs of binuclear Pt (II) complexes2, 3. This process is highly dependent on the configuration of molecular excited-state potential energy surfaces (PESs). However, due to the lack of guidelines and approaches for designing excited-state PESs, precise manipulation of PSC processes is still very challenging. In this project, a series of rationally designed butterfly-like phosphorescent binuclear platinum complexes were synthesized with well-controlled PESs and tunable dual emissions at room temperature. We demonstrated our capability to manipulate PESs in two ways. First, we introduce the steric bulkiness effect of both cyclometalated ligands and pyrazolate bridging ligands to control the transition energy barrier of PSC process. Based on the Bell-Evans-Polanyi principle, which describe a chemical reaction between two energy minima on the first triplet excited-state PES, we reveal a simple method to engineer the dual emission of molecular systems by manipulating PES and therefore PSC to achieve desired molecular properties. Second, we synthetically control the electronic structure of the cyclometallating ligand and the steric bulkiness of the pyrazolate bridging ligand at the same time to realize the precise manipulation of the PESs. Color tuning of dual emission from blue/red, to green/red and red/deep red have been achieved for these phosphorescent molecular butterflies, which have two well-controlled energy minima on the PESs. The environmentally dependent photoluminescence of these molecular butterflies enabled their application as self-referenced luminescent viscosity sensor.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Zhou_fsu_0071N_13904
Format: Thesis

Title: Leg Specialization Control: Deriving Control from the Perspective of Limb Function.
Creator: Carbiener, Charles P., Clark, Jonathan E., Ordonez, Camilo, Xu, Chengying, Collins, Emmanuel G., Florida State University, College of Engineering, Department of Mechanical...
Show moreCarbiener, Charles P., Clark, Jonathan E., Ordonez, Camilo, Xu, Chengying, Collins, Emmanuel G., Florida State University, College of Engineering, Department of Mechanical Engineering
Show less
Abstract/Description: Many leg controllers and gaits have been designed directly with lower level parameters. This approach can lead to very high performance gaits, but can also lead to platforms highly tuned for one particular application with drastically reduced performance elsewhere. Through the Leg Specialization (LSC) gait strategy presented here, an alternative approach is demonstrated. Designing controllers from the perspective of limb function allows for adaptation to various environments, and here has...
Show moreMany leg controllers and gaits have been designed directly with lower level parameters. This approach can lead to very high performance gaits, but can also lead to platforms highly tuned for one particular application with drastically reduced performance elsewhere. Through the Leg Specialization (LSC) gait strategy presented here, an alternative approach is demonstrated. Designing controllers from the perspective of limb function allows for adaptation to various environments, and here has produced a high performing gait capable of running on a variety of surfaces.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Carbiener_fsu_0071N_13986
Format: Thesis

Title: Open-Source Low-Cost Internet of Things Platform for Buildings.
Creator: Liu, Xiaorui, Arghandeh, Reza, Foo, Simon Y., Li, Hui, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Abstract/Description: Internet of Things (IOT) systems are becoming a popular concept of every smart system. Many people intend to develop various IOT systems which could be smart socket can be controlled remotely and tracking the electricity consumption to save energy or a security system for home which combines several sensors and cover a big area. The goal of this thesis was to introduce a method to construct an IOT system that can monitor different parameters. The design of this project also focused on...
Show moreInternet of Things (IOT) systems are becoming a popular concept of every smart system. Many people intend to develop various IOT systems which could be smart socket can be controlled remotely and tracking the electricity consumption to save energy or a security system for home which combines several sensors and cover a big area. The goal of this thesis was to introduce a method to construct an IOT system that can monitor different parameters. The design of this project also focused on wireless interaction in order to make the system more perceptual. The design of the system was modified several times which include a changing from using Ethernet to Wi-Fi. Ultimately, it provides an effective method for monitoring a building system which could be the temperature, humidity, photo intensity, or the movement of objects, etc. The final design fulfills the fundamental goals and there is a visualization web page for the IOT system which both includes a real time data monitoring and a real time charting. This thesis will give a thorough overview of how to build an own IOT system.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Liu_fsu_0071N_14126
Format: Thesis

Title: Removal of Powdered Activated Carbon by Cloth Tertiary Filters.
Creator: Madden, Brandon Cale, Ahmad, Hafiz, Chen, Gang, Tang, Youneng, Florida State University, College of Engineering, Department of Civil and Environmental Engineering
Abstract/Description: Water conservation, wastewater treatment regulations, and the use of reclaimed/reuse water supplies have been on a collision course since society’s demand began outstripping the supply of fresh water. As potable water demand has risen, engineers have looked toward Waste Water Treatment Plants (WWTP) to alleviate the stress placed upon aquifers and surface water sources. Direct Potable Reuse (DPR), Indirect Potable Reuse (IPR) and Reuse/Reclaimed systems all conserve water; however, they also...
Show moreWater conservation, wastewater treatment regulations, and the use of reclaimed/reuse water supplies have been on a collision course since society’s demand began outstripping the supply of fresh water. As potable water demand has risen, engineers have looked toward Waste Water Treatment Plants (WWTP) to alleviate the stress placed upon aquifers and surface water sources. Direct Potable Reuse (DPR), Indirect Potable Reuse (IPR) and Reuse/Reclaimed systems all conserve water; however, they also unintentionally conserve pollutants. The widespread use of WWTP effluent conservation requires additional treatment options such as Activated Carbon treatment to further treat plant effluent. Powdered Activated Carbon (PAC) has shown promise as a treatment method to reduce pollutants but challenges remain in effectively applying PAC to a wastewater stream. Of particular concern is the application of PAC to existing facilities in which the existing hydraulic profile does not allow the use of large sedimentation tanks normally associated with PAC use in potable water applications. Cloth Media Filtration (CMF) is an existing treatment process that has seen significant saturation into the WWTP market in the United States since being introduced in 1991. While mostly targeted at tertiary treatment, alternate processes such as primary filtration and storm water treatment are now being pursued. It is suspected that CMF will capture and retain Powdered Activated Carbon (PAC) in which the two processes could be combined in order to produce an energy friendly and cost competitive approach to pollutant reductions. This research examines the feasibility of application of PAC into existing hydraulic profiles by using inline injection and its quick removal by Cloth Media Filtration (CMF). One of the most challenging aspects of PAC usage is its removal, which can be facilitated by a commercial CMF. A bench sized cloth media filter was constructed and then operated in a side stream manner with a real-world wastewater treatment train. The results show excellent performance of the designed CMF. The removal of two commercially available PACs was more than 70% within a short time using the existing hydraulic conditions of the plant. Additionally, using the backwash rates and solids removal rates, it was determined that CMF performs as an acceptable means of removal for PAC in a WWTP.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Madden_fsu_0071N_14114
Format: Thesis

Title: Experimental Study of Controlled Surface Imperfection Effects on Vortex Asymmetry of Conical Bodies at High Angles of Incidence.
Creator: Rodriguez, Joseph, Kumar, Rajan (Professor of Mechanical Engineering), Oates, William, Shoele, Kourosh, Florida State University, College of Engineering, Department of...
Show moreRodriguez, Joseph, Kumar, Rajan (Professor of Mechanical Engineering), Oates, William, Shoele, Kourosh, Florida State University, College of Engineering, Department of Mechanical Engineering
Show less
Abstract/Description: At high angles of attack, asymmetric vortices are formed on the leeward side of flight vehicles with pointed forebodies due to the random surface imperfections near the forebody apex. These vortices induce adverse side forces and yaw moments. The forces generated are too large to be controlled using conventional control surfaces and can result in flight instability and loss of control. Although many studies have reported that random surface imperfections trigger vortex asymmetry, there is a...
Show moreAt high angles of attack, asymmetric vortices are formed on the leeward side of flight vehicles with pointed forebodies due to the random surface imperfections near the forebody apex. These vortices induce adverse side forces and yaw moments. The forces generated are too large to be controlled using conventional control surfaces and can result in flight instability and loss of control. Although many studies have reported that random surface imperfections trigger vortex asymmetry, there is a lack of understanding of how these imperfections directly correlate to the varying side force with roll orientation. The present study is aimed at gaining a better insight into the underlying flow physics of vortex asymmetry. This is accomplished by performing flow field measurements using Particle Image Velocimetry and force measurements using a six-component strain gage balance on an unpolished and a highly-polished 12° semi-apex angle cone at subsonic speeds. Measurements were carried out with and without the implementation of controlled surface imperfections. All experiments were performed at a fixed Reynolds number of 0.3 × 10^6 based on the base diameter of the cone model. The force measurements indicate that the vortices caused by the random surface imperfections are highly dependent on the magnitude of surface roughness. The results show that the side force was significantly reduced and was relatively less dependent on roll orientation for the polished cone. Flow field results show that the ratio of imperfection height to the local cross-flow boundary layer thickness was observed to be critical in influencing the vortex location and growth. Furthermore, the region of incipient boundary layer separation was highly sensitive to the controlled imperfections.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Rodriguez_fsu_0071N_14107
Format: Thesis

Title: Motion Planning Testing Environment for Robotic Skid-Steered Vehicles.
Creator: Pace, James, Collins, Emmanuel G., Clark, Jonathan E., Ordonez, Camilo, Shoele, Kourosh, Florida State University, College of Engineering, Department of Mechanical Engineering
Abstract/Description: One of the main goals of robotics research is to give physical platforms intelligence, allowing for the platforms to act autonomously with minimal direction from humans. Motion planning is the process by which a mobile robot plans a trajectory that moves the robot from one state to another. While there are many motion planning algorithms, this research focuses on Sampling Based Model Predictive Optimization (SBMPO), a motion planning algorithm that allows for the generation of trajectories...
Show moreOne of the main goals of robotics research is to give physical platforms intelligence, allowing for the platforms to act autonomously with minimal direction from humans. Motion planning is the process by which a mobile robot plans a trajectory that moves the robot from one state to another. While there are many motion planning algorithms, this research focuses on Sampling Based Model Predictive Optimization (SBMPO), a motion planning algorithm that allows for the generation of trajectories that are not only dynamically feasible, but also efficient in terms of a user defined cost function (specifically in this research, distance traveled or energy consumed). To accomplish this, SBMPO uses the kinematic, dynamic, and power models of the robot. The kinematic, dynamic, and power models of a skid-steered robot are dependent on the type and inclination of the terrain over which the robot is traversing. Previous research has successfully used SBMPO to plan trajectories on different inclinations and terrain types, but with the terrain type and inclination being held constant over the trajectory. This research extends the prior work to plan trajectories where the terrain type changes over the trajectory and where the robot has the option to go over or around hills, situations extremely common in real world environments encountered in military and search and rescue operations. Furthermore, this research documents the design and implementation of a 3D visualization environment which allows for the visualization of the trajectory generated by the planner without having a robot follow the trajectory in a physical environment.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Pace_fsu_0071N_14099
Format: Thesis

Title: Aeroacoustic Characteristics of Supersonic Impinging Jets.
Creator: Worden, Theodore James, Alvi, Farrukh S., Shih, Chiang, Liang, Zhiyong Richard, Collins, Emmanuel G., Gustavsson, Jonas, Kumar, Rajan (Professor of Mechanical Engineering),...
Show moreWorden, Theodore James, Alvi, Farrukh S., Shih, Chiang, Liang, Zhiyong Richard, Collins, Emmanuel G., Gustavsson, Jonas, Kumar, Rajan (Professor of Mechanical Engineering), Michalis, Krista, Florida State University, College of Engineering, Department of Mechanical Engineering
Show less
Abstract/Description: High-speed impinging jets are often generated by the propulsive systems of aerospace launch vehicles and tactical aircraft. In many instances, the presence of these impinging jets creates a hazard for flight operations personnel due to the extremely high noise levels and unsteady loads produced by fluid-surface interaction. In order to effectively combat these issues, a fundamental understanding of the flow physics and dominant acoustic behavior is essential. There are inherent challenges in...
Show moreHigh-speed impinging jets are often generated by the propulsive systems of aerospace launch vehicles and tactical aircraft. In many instances, the presence of these impinging jets creates a hazard for flight operations personnel due to the extremely high noise levels and unsteady loads produced by fluid-surface interaction. In order to effectively combat these issues, a fundamental understanding of the flow physics and dominant acoustic behavior is essential. There are inherent challenges in performing such investigations, especially with the need to simulate the flowfield under realistic operational conditions (temperature, Mach number, etc.) and in configurations that are relevant to full-scale application. A state-of-the-art high-temperature flow facility at Florida State University has provided a unique opportunity to experimentally investigate the high-speed impinging jet flowfield at application-relevant conditions. Accordingly, this manuscript reports the findings of several experimental studies on high-temperature supersonic impinging jets in multiple configurations. The overall objective of these studies is to characterize the complex relationship between the hydrodynamic and acoustic fields. A fundamental parametric investigation has been performed to document the flowfield and acoustic characteristics of an ideally-expanded supersonic air jet impinging onto a semi-infinite flat plate at ambient and heated jet conditions. The experimental program has been designed to span a widely-applicable geometric parameter space, and as such, an extensive database of the flow and acoustic fields has been developed for impingement distances in the range 1d to 12d, impingement angles in the range 45 degrees to 90 degrees, and jet stagnation temperatures from 289K to 811K (TTR=1.0 to 2.8). Measurements include point-wise mean and unsteady pressure on the impingement surface, time-resolved shadowgraphy of the flowfield, and fully three-dimensional near field acoustics. Aside from detailed documentation of the flow and acoustic fields, this work aims to develop a physical understanding of the noise sources generated by impingement. Correlation techniques are employed to localize and quantify the spatial extent of broadband noise sources in the near-impingement region and to characterize their frequency content. Additionally, discrete impingement tones are documented for normal and oblique incidence angles, and an empirical model of the tone frequencies has been developed using velocity data extracted from time-resolved shadowgraphy together with a simple modification to the conventional feedback formula to account for non-normal incidence. Two application-based studies have also been undertaken. In simulating a vertical take-off and landing aircraft in hover, the first study of a normally-impinging jet outfitted with lift-plate characterizes the flow-acoustic interaction between the high-temperature jet and the underside of an aircraft and documents the effectiveness of an active flow control technique known as `steady microjet injection' to mitigate high noise levels and unsteady phenomena. The second study is a detailed investigation of the jet blast deflector/carrier deck configuration aimed at gaining a better understanding of the noise field generated by a jet operating on a flight deck. The acoustic directionality and spectral characteristics are documented for a model-scale carrier deck with particular focus on locations that are pertinent to flight operations personnel.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Worden_fsu_0071E_13997
Format: Thesis

Title: Characterization of the Flow-Field for Dual Normally Impinging Axi-Symmetric Jets.
Creator: Harmon, Malcolm Jerrod, Alvi, Farrukh S., Kumar, Rajan (Professor of Mechanical Engineering), Collins, Emmanuel G., Florida State University, College of Engineering, Department...
Show moreHarmon, Malcolm Jerrod, Alvi, Farrukh S., Kumar, Rajan (Professor of Mechanical Engineering), Collins, Emmanuel G., Florida State University, College of Engineering, Department of Mechanical Engineering
Show less
Abstract/Description: In this study, the flow and acoustic field characteristics of dual high-speed axi-symmetric impinging jets will be examined. Initially, the short takeoff and vertical landing (STOVL) facility was redesigned by adding a second jet to the existing model there by achieving a dual jet configuration. This modified facility was designed to simulate aircraft hover in proximity to the ground. Emphasis is placed on the complex behavior of the jets as the nozzle pressure ratio (NPR) is varied to...
Show moreIn this study, the flow and acoustic field characteristics of dual high-speed axi-symmetric impinging jets will be examined. Initially, the short takeoff and vertical landing (STOVL) facility was redesigned by adding a second jet to the existing model there by achieving a dual jet configuration. This modified facility was designed to simulate aircraft hover in proximity to the ground. Emphasis is placed on the complex behavior of the jets as the nozzle pressure ratio (NPR) is varied to produce over-expanded, ideally-expanded and under-expanded jet flows. Two nozzle configurations were chosen to simulate dual impinging jets: 1) two converging nozzles (Mach design, Md = 1.00) and 2) a converging nozzle (Md = 1.00) and a converging-diverging (CD) nozzle (Md = 1.50). The experimental results described in this thesis include shadowgraph flow visualization, surface pressure measurements, and near-field acoustic measurements. Shadowgraph flow visualization was used to observe the acoustic field and the coupling between dual jets for various NPR combinations. Mean surface pressure measurements were obtained for impinging jet configurations which analyzed the jet behavior for ground plane separations ranging from x/D = 2 to 10. These measurements provided information regarding the footprint of the flow-field, particularly the fountain flow behavior. It was found that there is a shift in the fountain flow region which occurs when the NPR of one jet was substantially higher than the supplementary jet. Unsteady pressure measurements and near-field acoustic measurements investigated the presence of a feedback loop that occurs for both free and impinging jets, under certain conditions. The presence of tones, either screech or impingement, was clearly evident from the spectral peaks in the near-field noise spectra. When such tones are present, the corresponding flow-field images show strong acoustic waves.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Harmon_fsu_0071N_14049
Format: Thesis

Title: Risk-Benefit Analysis and Optimization of LEED-Certified School Buildings Design and Construction: Statisitical and Machine Learning Approaches.
Creator: Doczy, Ryan Daniel, Boot, Walter Richard, Sobanjo, John Olusegun, Spainhour, Lisa, Florida State University, College of Engineering, Department of Civil and Environmental...
Show moreDoczy, Ryan Daniel, Boot, Walter Richard, Sobanjo, John Olusegun, Spainhour, Lisa, Florida State University, College of Engineering, Department of Civil and Environmental Engineering
Show less
Abstract/Description: As the strategy of green building becomes more and more popular due to a combination of environmental and economic concerns, there develops a need for clearly being able to understand the potential implications for choosing green strategies over conventional building practices. Some of the regions of interest consist of the additional upfront costs associated with green practices, potential life-cycle benefits associated with green building components, potential energy savings, and the...
Show moreAs the strategy of green building becomes more and more popular due to a combination of environmental and economic concerns, there develops a need for clearly being able to understand the potential implications for choosing green strategies over conventional building practices. Some of the regions of interest consist of the additional upfront costs associated with green practices, potential life-cycle benefits associated with green building components, potential energy savings, and the ability to reduce emissions. Many of these areas can potentially be forecasted with a fair degree of certainty (e.g. energy consumption, additional upfront costs); however, some elements of green building are less well defined. One such area consists of the ability of green buildings to improve the productivity and well-being of its inhabitants through an improved indoor environmental quality (IEQ). It is difficult to grasp just how much a healthier and cleaner environmental can impact a person’s cognitive functions, mental state, and physical health. Several studies shown in the literature review of this paper lead show a positive correlation between green buildings and reductions in asthma symptoms, depression symptoms, improved well-being due to reductions in contaminants, a reduction in sick building syndrome (SBS) and building related illness (BRI). This paper aims to do what many have done before in attempting to quantify the potential impact that sustainable buildings can have on its occupants; however, the scope and methods to determine these potential correlations will differ. Perhaps the most noticeable difference will be in the paper’s focus on attempting to measure the potential impact that LEED (Leadership in Energy and Environmental Design) accredited schools have on their student occupants by measuring their productivity via the use of standardized test scores and attendance rates compared to those students in conventional (non-LEED) schools. To develop a balanced analysis, the paper will control for various school-related and socio-economic factors (e.g. economic status, race, percent of teachers with a Master’s degree or higher). To make a judgement on the effect that sustainability has on academic achievement and student wellbeing, 2 sample t-tests, regression analysis, and M5P decision trees will be implemented to determine if there are significant differences between LEED and conventional schools and to determine the relationship between LEED and non-LEED parameters on student achievement and wellbeing metrics. To ensure that a large population of students from across the nation are accounted for, the study intends on investigating at least three states-worth of student data. These states (Florida, New York and Virginia) are in different climates, thus allowing for an examination of the potential differences between the various climate zones and building codes. Lastly, a case study building information model (BIM) of College Park Elementary School (located in Virginia) will be run through the energy modeling (EM) software, Ecotect, to provide information related to the school’s annual energy consumption, acoustics, and daylight and lighting values. An optimization equation, developed using previous literature and findings from this study, will use information from the case study in an attempt to optimize its academic performance. The equation will attempt to minimize construction and operational costs while maximizing student performance metrics. The optimization equation will be run through NEOS server’s Nonlinearly Constrained Optimization, Knitro. The purpose of this study is to inform those decision-makers involved in the construction of schools, and who may be interested in obtaining LEED certification for the school, to what extent the LEED schools benefit the school’s student academic achievement levels. Accounting for soft benefits (e.g. productivity, morale, general wellbeing) in a cost-benefit analysis invites an element of risk due to the difficulties in soliciting, obtaining, and accurately measuring these performance metrics. When considering fields involving knowledge work, accurately measuring productivity is an inexact science that normally requires building occupants to perform self-examinations. The results from these examinations are reliant on the occupant’s perceptions and could be open to bias. This study avoids self-assessments through its use of standardized testing as a measure for productivity. The proposed outcome of this paper is that the impacts of LEED schools on their occupants’ academic achievement, health, and wellbeing will be better understood and easier to quantify. The authors hypothesize that LEED schools will outperform conventional schools, which can be attributed to improved IEQ due to tighter building envelopes, increased ventilation rates, better filtration, a reduction in building or cleaning products containing volatile organic compounds, etc. An absence of this data could point to the inability of LEED schools to directly impact their students in a meaningful way, particularly its Indoor Environmental Quality credits, which means that LEED could have to rethink its standards if it wishes to truly improve the productivity and wellbeing of its occupants.
Show less
Date Issued: 2018
Identifier: 2018_Su_Doczy_fsu_0071E_14648
Format: Thesis

Title: Investigation of the Osmotic Drying of Alumina-Gelatin Objects Utilizing an Aqueous Poly(Ethylene glycol) Liquid Desiccant.
Creator: Hammel, Emily Catherine, Okoli, Okenwa O. I., Hruda, Simone Peterson, Liang, Zhiyong, Zhang, Mei, Florida State University, College of Engineering, Department of Industrial and...
Show moreHammel, Emily Catherine, Okoli, Okenwa O. I., Hruda, Simone Peterson, Liang, Zhiyong, Zhang, Mei, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Advanced ceramics and ceramic composites have a variety of advantageous properties, such as high hardness, strength, and wear resistance. This makes them good candidates for materials in the aerospace, automotive and defense industries, among others. A major disadvantage of advanced ceramics and ceramic composites is their requirement for specialized processing which often makes manufacturing complex shaped ceramic objects challenging and costly. Additionally, these materials are susceptible...
Show moreAdvanced ceramics and ceramic composites have a variety of advantageous properties, such as high hardness, strength, and wear resistance. This makes them good candidates for materials in the aerospace, automotive and defense industries, among others. A major disadvantage of advanced ceramics and ceramic composites is their requirement for specialized processing which often makes manufacturing complex shaped ceramic objects challenging and costly. Additionally, these materials are susceptible to flaw incorporation during production. These flaws are initiation points for failure and thus lead to a drastic reduction in strength. Repeatable manufacturing methods and optimized processes are compulsory for cost saving and production of high quality parts. In recent years, new processing technologies, such as gelcasting, have been developed to accommodate the formation of complex shaped ceramics and also the manufacture of ceramic composites. The use of wet forming technologies, like slip casting or gelcasting, necessitates the careful drying of ceramic objects. Complex shaped objects are particularly difficult to properly dry without introducing internal stresses which may result in warping and cracking, thus rendering the object unusable. Additionally, traditional drying processes are often energy intensive and lengthy, neither of which are favorable in a production setting. To improve manufacturability, the processing-structure-property relationships developed during the drying process must be investigated further. This work addresses the need to define optimized process conditions for the drying of alumina objects gelcast using gelatin. The osmotic drying process was employed to remove solvent from the objects through the use of an aqueous liquid desiccant solution of poly(ethylene glycol) (PEG). The process settings for the solution’s osmotic pressure and molecular weight were investigated, in addition to the total immersion time. The mass transfer processes that occurred between the ceramic object and the liquid desiccant solution were quantified in several case studies. For one sample, 40 weight% of the initial water content was removed in 75 minutes demonstrating the potential drying efficiency of this method. Depending on the initial solution conditions, the PEG solute was found to diffuse into the ceramic object to varying degrees. The effect of the drying condition on the object’s density and hardness was also measured. Through the development of regression equations, the process settings were optimized based on the goals to maximize water loss, minimize solids gain, and maximize the object’s density. The optimum drying settings for the objects studied in this work were an osmotic pressure of 2.50 MPa, a molecular weight of at least 100,000 g/mol, and an immersion time of 60 minutes. When objects of similar geometry, composition, and solution-to-object volume ratio are immersed in this type of solution, they are expected to lose 28 weight% of the object’s initial water content, gain solids of 0.82 weight% of the object’s initial mass, and have a density of 3.54 g/cm3. Furthermore, the regression models were validated using an independent experimental study. A model based on mass balance was used to define the kinetics of the mass transfer, along with the equilibrium values. Lastly, a demonstration of the feasibility of combining gelcasting, osmotic drying, and sacrificial templating is presented. Overall, these results may be used as the basis for further investigation into the scale up of the osmotic drying of gelcast alumina with the eventual implementation of the process in an industrial setting.
Show less
Date Issued: 2018
Identifier: 2018_Su_Hammel_fsu_0071E_14711
Format: Thesis

Title: Flow Physics and Nonlinear Dynamics of Separated Flows Subject to ZNMF-Based Control.
Creator: Deem, Eric Anthony, Cattafesta, Louis N., Sussman, Mark, Taira, Kunihiko, Collins, E., Moore, Matthew Nicholas J., Hemati, Maziar, Florida State University, College of...
Show moreDeem, Eric Anthony, Cattafesta, Louis N., Sussman, Mark, Taira, Kunihiko, Collins, E., Moore, Matthew Nicholas J., Hemati, Maziar, Florida State University, College of Engineering, Department of Mechanical Engineering
Show less
Abstract/Description: Aircraft, turbomachinery, wind turbines, and other systems that generate or rely on aerodynamic forces are designed to operate most efficiently when flows are fully attached. However, especially due to increasing off-design performance requirements, there is significant risk of inefficient operation or failure due to flow separation. This work formulates a procedure for extending the performance envelope of many fluidic systems by delaying flow separation through real time separated flow...
Show moreAircraft, turbomachinery, wind turbines, and other systems that generate or rely on aerodynamic forces are designed to operate most efficiently when flows are fully attached. However, especially due to increasing off-design performance requirements, there is significant risk of inefficient operation or failure due to flow separation. This work formulates a procedure for extending the performance envelope of many fluidic systems by delaying flow separation through real time separated flow state estimation and control. The history of active separation control is rich; however the approach presented here is novel in that it employs "real time" dynamical system updates to track nonlinear variations in the flow and provide robustness to flow state conditions. First, the dynamics of the canonical laminar separated flow over a flat plate at Rec=10⁵ are characterized by employing full-field, time-resolved PIV and unsteady surface pressure measurements. Dynamic Mode Decomposition (DMD) is employed on the high dimensional PIV velocity fields to identify the dynamically relevant spatial structure and temporal characteristics of the separated flow. Then, results of various cases of open-loop control using a zero-net mass flux actuator slot located just upstream of separation are presented that show separation reduction occurs for the employed actuation method. Real time estimates of the dynamical characteristics are provided by performing online DMD on measurements from a linear array of unsteady surface pressure transducers. The results show that online DMD of the pressure measurements provides reliable estimates of the modal characteristics of the separated flow subject to forcing. Furthermore, the dynamical estimates are updated at a rate commensurate with the characteristic time scales of the flow. Therefore, as the separated flow reacts to the applied forcing, online DMD applied to the surface pressure measurements provides a time-varying linear estimate of the evolution of the flow. Building upon these results, methods for adaptive control of flow separation based on the model provided by online DMD are formulated and implemented on the separated flow. Feedback control is implemented in which Linear Quadratic Regulator gains are computed recursively as the model provided by online DMD is updated. This physics-motivated, autonomous approach results in more efficient flow reattachment, requiring approximately 30% less actuator effort as compared with the commensurate open loop forcing case. Since this approach relies solely on observations of the separated flow, it is robust to variable flow conditions. Additionally, this approach does not require prior knowledge of the characteristics of the separated flow.
Show less
Date Issued: 2018
Identifier: 2018_Su_Deem_fsu_0071E_14530
Format: Thesis

Title: Impact of Connected and Autonomous Vehicles on Freeway Traffic Operations.
Creator: Theophilus, Oluwatosin Paul, Sobanjo, John Olusegun, Ozguven, Eren Erman, Dulebenets, Maxim A., Florida State University, College of Engineering, Department of Civil and...
Show moreTheophilus, Oluwatosin Paul, Sobanjo, John Olusegun, Ozguven, Eren Erman, Dulebenets, Maxim A., Florida State University, College of Engineering, Department of Civil and Environmental Engineering
Show less
Abstract/Description: This project evaluates using traffic simulation, the performance of a mixed traffic composition of Connected and Autonomous Vehicles (CAV) and conventional or human-driven vehicles, in comparison with the performance of the existing traffic composition of only conventional vehicles on a freeway segment. The introduction of CAVs into the existing transportation system is a phase in the evolution of automobile traffic currently generating a lot of concerns and questions that needs to be...
Show moreThis project evaluates using traffic simulation, the performance of a mixed traffic composition of Connected and Autonomous Vehicles (CAV) and conventional or human-driven vehicles, in comparison with the performance of the existing traffic composition of only conventional vehicles on a freeway segment. The introduction of CAVs into the existing transportation system is a phase in the evolution of automobile traffic currently generating a lot of concerns and questions that needs to be answered before the full deployment of these vehicles. Traffic simulation presents a safer and cost-effective approach to evaluating this innovative technology when compared with real world testing. Connected and autonomous vehicles (CAV) are designed to improve traffic operations, as the difference in their driving behavior from regular vehicles suggests a reasonable tendency to change the traffic flow pattern. However the issue being examined in this project is whether there would be a significant change in traffic operations resulting from their deployment, and also to verify whether the change is an improvement of the existing traffic condition in terms of performance measures used for the evaluation. Data was collected from the I-95 Freeway in South Florida, and used in the development of a traffic microsimulation model, in VISSIM. The model was calibrated using minimum error algorithm implemented in MATLAB to determine the optimal value of the two model parameters considered -- stand still distance (CC0), and headway time (CC1). The calibrated model was used as the base model and CAVs are incorporated into the base model in 10% increment, to examine their effect on the base model. The performance measures are average hourly speed, hourly traffic volume, travel time, delay, and safety. Findings show that for every increment in CAV market penetration, there is a change of 6.52% - 48% in the capacity of the freeway, 40% reduction in travel time, more than 30% reduction in delay per vehicle, more than 26% increase in average speed of the traffic at high demand volumes.
Show less
Date Issued: 2018
Identifier: 2018_Su_Theophilus_fsu_0071N_14809
Format: Thesis

Title: Impedance Measurement Techniques in Noisy Medium Voltage Power Hardware-in-the-Loop Environments.
Creator: Chauncey, Gunnar Luke, Li, Hui, Steurer, Michael, Yu, Ming, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Abstract/Description: In Power Hardware-In-The-Loop (PHIL) simulations, it is important to understand the impedance characteristics of the system being tested. These impedances are used in the assessment of both the stability and the accuracy of the PHIL simulation experiment, as well as for stability analyses for the integration of the device under test (DUT) into the eventual system of deployment. When testing medium voltage systems in the megawatt power range, sensor noise stemming from the switching amplifiers...
Show moreIn Power Hardware-In-The-Loop (PHIL) simulations, it is important to understand the impedance characteristics of the system being tested. These impedances are used in the assessment of both the stability and the accuracy of the PHIL simulation experiment, as well as for stability analyses for the integration of the device under test (DUT) into the eventual system of deployment. When testing medium voltage systems in the megawatt power range, sensor noise stemming from the switching amplifiers can become quite an issue. This thesis evaluates four different impedance measurement techniques to find a reliable, accurate, and quick assessment over a wide frequency range in the noisy environments of medium voltage systems. (1) a single tone consisting of one sine wave at a single frequency, (2) a multitoned signal which is the sum of multiple sine waves, each at a unique frequency, (3) a frequency-swept sine wave, also known as a “chirp”, and (4) a pseudorandom binary sequence. Each of these signals are injected into the system while energized in order to measure the response, which is then processed for the impedance characteristics. Various tests are conducted to simulated systems with simulated sensor noise to determine the viability of each of the techniques. Once the techniques are determined to be appropriate signals for system characterization in noisy medium voltage systems, they will be applied to a simulated Multilevel Modular Converter (MMC) model. The data from the simulated model will then be verified with a hardware experimental verification test with the viable signals chosen.
Show less
Date Issued: 2018
Identifier: 2018_Su_Chauncey_fsu_0071N_14782
Format: Thesis

Title: Network-Theoretic and Data-Based Analysis and Control of Unsteady Fluid Flows.
Creator: Nair, Aditya Gopimohan, Taira, Kunihiko, Sussman, Mark, Cattafesta, Louis N., Oates, William, Alvi, Farrukh S., Brunton, Steven L. (Steven Lee), Florida State University,...
Show moreNair, Aditya Gopimohan, Taira, Kunihiko, Sussman, Mark, Cattafesta, Louis N., Oates, William, Alvi, Farrukh S., Brunton, Steven L. (Steven Lee), Florida State University, College of Engineering, Department of Mechanical Engineering
Show less
Abstract/Description: Unsteady fluid flows have complex dynamics due to the nonlinear interactions amongst vortical elements. In this thesis, a network-theoretic framework is developed to describe vortical and modal (coherent structure) interactions in unsteady fluid flows. A sparsified-dynamics model and a networked-oscillator model describe the complex dynamics in fluid flows in terms of vortical and modal networks, respectively. Based on the characterized network interactions, model-based feedback control laws...
Show moreUnsteady fluid flows have complex dynamics due to the nonlinear interactions amongst vortical elements. In this thesis, a network-theoretic framework is developed to describe vortical and modal (coherent structure) interactions in unsteady fluid flows. A sparsified-dynamics model and a networked-oscillator model describe the complex dynamics in fluid flows in terms of vortical and modal networks, respectively. Based on the characterized network interactions, model-based feedback control laws are established, particularly for controlling the flow unsteadiness. Furthermore, to characterize model-free feedback control laws for suppressing flow separation in turbulent flows, a data-driven approach leveraging unsupervised clustering is developed. This approach alters the Markov transition dynamics of fluid flow trajectories in an optimal manner using a cluster-based control strategy. To describe vortical interactions, dense fluid flow graphs are constructed using discrete point vortices as nodes and induced velocity as edge weights. Sparsification techniques are then employed on these graph representations based on spectral graph theory to construct sparse graphs of the overall vortical interactions which maintain similar spectral properties as the original setup. Utilizing the sparse vortical graphs, a sparsified-dynamics model is developed which drastically reduces the computational cost to predict the dynamical behavior of vortices, sharing characteristics of reduced-order models. The model retains the nonlinearity of the interactions and also conserves the invariants of discrete vortex dynamics. The network structure of vortical interactions in two-dimensional incompressible homogeneous turbulence is then characterized. The strength distribution of the turbulence network reveals an underlying scale-free structure that describes how vortical structures are interconnected. Strong vortices serve as network hubs with smaller and weaker eddies predominantly influenced by the neighboring hubs. The time evolution of the fluid flow network informs us that the scale-free property is sustained until dissipation overtakes the flow physics. The types of perturbations that turbulence network is resilient against is also examined. To describe modal interactions in fluid flows, a networked-oscillator-based analysis is performed. The analysis examines and controls the transfer of kinetic energy for periodic bluff body flows. The dynamics of energy fluctuations in the flow field are described by a set of oscillators defined by conjugate pairs of spatial POD modes. To extract the network of interactions among oscillators, impulse responses of the oscillators to amplitude and phase perturbations are tracked. Using linear regression techniques, a networked oscillator model is constructed that reveals energy exchanges among the modes. In particular, a large collection of system responses are aggregated to capture the general network structure of oscillator interactions. The present networked oscillator model describes the modal perturbation dynamics more accurately than the empirical Galerkin reduced-order model. The linear network model for nonlinear dynamics is subsequently utilized to design a model-based feedback controller. The controller suppresses the modal fluctuations and amplitudes that result in wake unsteadiness leading to drag reduction. The strength of the approach is demonstrated for a canonical example of two-dimensional unsteady flow over a circular cylinder. The network-based formulation enables the characterization and control of modal interactions to control fundamental energy transfers in unsteady bluff body flows. Finally, unsupervised clustering and data-driven optimization of coarse-grained control laws is leveraged to manipulate post-stall separated flows. Optimized feedback control laws are deduced in high-fidelity simulations in an automated, model-free manner. The approach partitions the baseline flow trajectories into clusters, which corresponds to a characteristic coarse-grained phase in a low-dimensional feature space constituted by feature variables (sensor measurements). The feedback control law is then sought for each and every cluster state which is iteratively evaluated and optimized to minimize aerodynamic power and actuation power input. The control optimally transforms the Markov transition network associated with the baseline trajectories to achieve desired performance objectives. The approach is applied to two and three-dimensional separated flows over a NACA 0012 airfoil at an angle of attack of 9° Reynolds number Re = 23000 and free-stream Mach number M∞ = 0.3. The optimized control law minimizes power consumption for flight enabling flow to reach a low-drag state. The analysis provides insights for feedback flow control of complex systems characterizing global cluster-based control laws based on a data-driven, low-dimensional characterization of fluid flow trajectories. In summary, this thesis develops a novel network-theoretic and data-based framework for analyzing and controlling fluid flows. The framework incorporates advanced mathematical principles from network science, graph theory and dynamical systems to extract fundamental interactions in fluid flows. On manipulating these interactions, wake unsteadiness in bluff body flow is reduced leading to drag reduction. Finally, data-based methods are developed to deduce optimal feedback control laws for post-stall separated flows. The network-theoretic and data-based approaches provides insights on fundamental interactions in fluid flows which paves the way for design of novel flow control strategies.
Show less
Date Issued: 2018
Identifier: 2018_Su_Nair_fsu_0071E_14745
Format: Thesis

Title: A New Two-Stage Game Framework for Power Demand Response Management in Smart Grids.
Creator: Fan, Huipu, Yu, Ming, Liu, Xiuwen, Tung, Leonard J., Andrei, Petru, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Abstract/Description: Recently, the smart grid technologies have been developed rapidly recently, which an important component is the so called demand response management (DRM). With the help of a DRM program, a utility company can adjust the power demand and electricity price to reduce the cost of power generation and consumption. However, there are many problems in DRM need to be solved. For example, to solve the problem of optimizing a generator's power (GP), the conventional methods such as economic dispatch ...
Show moreRecently, the smart grid technologies have been developed rapidly recently, which an important component is the so called demand response management (DRM). With the help of a DRM program, a utility company can adjust the power demand and electricity price to reduce the cost of power generation and consumption. However, there are many problems in DRM need to be solved. For example, to solve the problem of optimizing a generator's power (GP), the conventional methods such as economic dispatch (EDP) may reduce the profit of the utility company. To solve the problem of optimizing a consumer's power (CP), the existing smart pricing strategies may reduce the long-term benefits of the customers. This dissertation aims to develop a two-stage game model to increase the profit of the utility company and while increase the long-term benefit of the customers. For solving the GP. It is critical for the power generator and utility company to allocate the power demand properly, but the profit for the utility company may be reduced. To solve the CP, it is difficult for the customers to achieve a long-term beneficial power-usage-pattern with myopic pricing strategies. The stability of the smart grid and the benefit of the customers may also be reduced due to the myopic pricing strategies. It is difficult for the utility company to use the existing methods (e.g., EDP) to order an optimal power demand from the power generators to earn the maximum profit. There are two issues that are needed to be solved in the GP. First, the weight function for the utility company and power generators in the GP is not established properly in the existing methods. For example, the value of the weight function for the utility company and power generators are usually the same in an EDP method. However, in a smart grid, the utility company has the privilege to demand the power while the power generators must follow the demand. Hence the value of weight function for the utility company should be greater than the one for the power generators in a GP. Second, the optimal demand for the utility company is most likely not the optimal generation for the generators. The imbalanced power will increase the generation cost significantly. It is also difficult for a utility company to maintain an efficient DRM for a long-time period by using the existing smart pricing strategies. Applying incentive is the major solution for the utility company to influence the power demand of a customer. However, the traditional pricing strategies are shortsightedly designed, by which the long-time efficiency for the DRM is reduced. For example, the trigger punishment strategy applies a punishing price to a customer for a long period when a non-cooperation behavior is detected. During the punishment period, the customer chooses its power consumption freely since the punishment will be applied anyway. Such selfish behaviors reduce the long-term efficiency for the DRM and the stability of the smart grid. In this dissertation, we propose a two-stage game model to solve the GP and CP to increase the long-term efficiency for the DRM, maintain the stability of the smart grid, and also increase the profit of the utility company. In the first stage, a Stackelberg game model is applied to solve the GP, in which the utility company is the leading player while the generators are the following players. We prove that the GP for the following players is a convex problem mathematically. The following players achieve the Nash equilibrium (NE) state by choosing the unique optimal generation. The leading player reacts with this unique generation to achieve the optimal profit. Both the leading and following players reach an agreement in the NE state, in which they have no motivation to deviate the optimal actions. A genetic algorithm is developed to obtain the optimal demand for the leading and following players. In addition, we introduce a power balance constraint to the leading and following players to avoid the cost caused by the imbalanced power. By applying the constraint, the generated power is equal to the demand all the time. The smart grid will not need to store the excessive power in the energy storage unit or send the power back to the power generators to keep them idling. The cost is avoided and the efficiency of the DRM is increased. In the second stage, a repeated game model is applied to solve the CP, in which the customers are the players. The strategy for the players is to minimize the individual power consumption of each customer. The utility function for the players is the cost of the customers. The objective for the players is to minimize the cost. In this work, we prove that the NE state exists for the repeated game. However, it has been shown that in the NE state, the players' myopic behaviors may reduce the benefits for the entire group of players. To avoid the loss, we use a genetic algorithm to find the Pareto-efficient solution for the players, in which no player can increase its benefit by reducing other players' benefit. We apply a Tit-for-Tat (TFT) smart pricing strategy to increase the punishment strength from the utility company. Once an irrational behavior from a player is detected, a punishment will be applied to the player for a short period of time. The player can choose to cooperate or not during the punishment period. Compared to the existing smart pricing strategies, the long-term benefit for the smart grid is increased by applying the TFT strategy to the customers. The numerical simulations in different scenarios are conducted to evaluate the performance of the proposed two-stage game framework by using MATLAB. All the parameters and constraints of the related components are from the Department of Energy's report and the Oasisui online database. Five power generators, one utility company, and one hundred customers have been used in the simulations. Compared with the existing solutions (e.g., EDP and gaming optimization), the cost in power consumption is reduced by 6% percent while the profit for power generation is increased by 8% percent in our test scenarios. With the help of the proposed model, we enhance the efficiency for the DRM. The peak-to-average ratio (PAR) of the power demand of our work is compared with the EDP method. The effect of the PAR is studied. The numerical results show that the proposed model has a similar PAR to that of the EDP method, which implies that the proposed model has no negative influence on the stability of the smart grid. The punishing effort of the TFT strategy is compared with the trigger strategy (TP) to study the punishment influence on the customers. The numerical results show that the customers who are applied with the TFT strategy are more willing to cooperate with the utility company. The impact of the power loss ratio and different types of customers is also simulated and analyzed. The simulation results show that the players with a greater transmission loss ratio are more willing to cooperate. The customers that are associated with a greater linear dissatisfaction coefficient are more concerned about the dissatisfaction cost. The customers with greater price-sensitive coefficients are more concerned about the consumption cost. In summary, compared to the existing solutions, the proposed two-stage game model improves the performance of the DRM while maintain the stability of the smart grid. We also discuss the future research issues in the related areas.
Show less
Date Issued: 2018
Identifier: 2018_Su_Fan_fsu_0071E_14654
Format: Thesis

Title: Distributed Adaptive Droop Control for Power Management in DC Distribution Systems.
Creator: Perkins, Dallas, Edrington, Christopher S., Ordóñez, Juan Carlos, Foo, Simon Y., Moss, Pedro L., Florida State University, College of Engineering, Department of Electrical and...
Show morePerkins, Dallas, Edrington, Christopher S., Ordóñez, Juan Carlos, Foo, Simon Y., Moss, Pedro L., Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: The current trend for naval destroyer-class ships is the move toward DC distribution systems as the next generation of ships is developed. The main motivation for using DC is to increase the power density of the ships to accommodate advanced weaponry such as the electromagnetic railgun. The distribution systems are also expected to be modular and plug-n-play in nature, leading toward a distributed control scheme to integrate the distributed sources and loads that could be online at any given...
Show moreThe current trend for naval destroyer-class ships is the move toward DC distribution systems as the next generation of ships is developed. The main motivation for using DC is to increase the power density of the ships to accommodate advanced weaponry such as the electromagnetic railgun. The distribution systems are also expected to be modular and plug-n-play in nature, leading toward a distributed control scheme to integrate the distributed sources and loads that could be online at any given time. One of the main performance requirements for the future power distribution systems is the ability to accurately share power among the distributed resources on the ship, while also maintaining the voltage stability of the distribution system, often referred to as power management. The primary candidate to accomplish the power management of the ship systems is droop control. Droop control has been extensively studied for terrestrial applications for sharing power between paralleled sources. Specifically, its application to DC microgrids is of interest since islanded microgrids have similar properties to ship systems. In these studies, it has been shown that conventional droop control is limited in its power sharing capabilities due to a tradeoff between the accuracy of the power sharing between devices and the regulation of the bus voltage. Secondary controllers have been proposed to modify the droop control scheme to alleviate these issues based on linear controllers or heuristic methods. However, accurate models for DC microgrids are difficult to derive for linear control design, and heuristic methods do not present an autonomous way to adjust the parameters of the controller. Therefore, adaptive control is proposed to adjust the droop controller’s parameters in an online fashion to find the optimal values based on the system conditions. Model reference adaptive control is chosen in this research for its ability to deal with system uncertainties and ensure stability. Specifically, combined model reference adaptive control is chosen for its improvements in transient response and robustness over the direct and indirect versions. The method is developed and simulated using MATLAB/Simulink to determine the performance of the algorithm. Additionally, a notional MVDC ship power system is developed in the same environment to provide a test system with various distributed sources and loads. A load profile is developed for the main system components such as propulsion, service loads, and the advanced weaponry to reflect a notional battle scenario. The algorithm is first tested in simulation, and then deployed to external distributed controllers to validate the performance of the power management scheme under hardware constraints and communication latency. The algorithm is also demonstrated in conjunction with a management layer for distributed energy storage modules throughout the ship system to further illustrate the real-world viability of the method.
Show less
Date Issued: 2018
Identifier: 2018_Su_Perkins_fsu_0071E_14716
Format: Thesis

Title: Distributed Energy Management Utilizing Model Predictive Control for Naval Ship Applications.
Creator: Gonsoulin, David E., Clark, Jonathan E., Faruque, Md Omar, Pamidi, Sastry V., Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Abstract/Description: Future Naval vessels are looking to incorporate a new variety of electrical loads. These loads include rail guns, high power radars, electric propulsion drives, and lasers. These loads, especially the rail gun, can be classified as high-power ramp rate loads. Before now, these types of loads were not prevalent on naval vessels; therefore, generators were used throughout the ship to power a multitude of devices that did not require high-power ramp rates. Many of the generators had a specific...
Show moreFuture Naval vessels are looking to incorporate a new variety of electrical loads. These loads include rail guns, high power radars, electric propulsion drives, and lasers. These loads, especially the rail gun, can be classified as high-power ramp rate loads. Before now, these types of loads were not prevalent on naval vessels; therefore, generators were used throughout the ship to power a multitude of devices that did not require high-power ramp rates. Many of the generators had a specific purpose; there were no interconnections between generators. With these new types of loads, a power system that can accommodate these devices is needed. Integrated Power Systems (IPS) look to solve the high-power ramp rate issue as well as provide a multitude of benefits such as efficiency, resiliency, and reconfigurability. The generators, loads, energy storages, protections, etc. will all be located and connected within the IPS. The IPS can provide the foundation to achieve a multitude of benefits; however, the control system must be intelligent in order to realize the IPS’ full potential. Part of the control problem is how to manage sources and loads to ensure load demand is met. In terrestrial systems, the near infinite bus takes care of changes in load demand. In a microgrid, such as those found on ships, a large change in load demand, such as those seen by high-power ramp rate loads, can have adverse effects on the power system and devices connected to the power system. The control must coordinate the sources and/or loads to ensure load demand is met with minimal impact to the system. In this dissertation, the beginnings of a distributed Energy Management control layer are shown. The control layer looks to assist in realizing the IPS’ full potential. This is done by providing a distributed type of control to fortify the resiliency and reliability, ensuring load demand is met, and certifying the energy storages state of charge is maintained to ensure an ever-ready presence. This control layer aims to meet load demand, ensure device constraints (power ratings, ramp rate limitations, etc.) are not exceeded, and maintain the energy storages desired state of charge. The control objective is met through a combined approach of a distributed spinning reserve algorithm and distributed MPC. The distributed MPC utilizes the distributed optimization technique called the Alternating Direction Method of Multipliers (ADMM).
Show less
Date Issued: 2018
Identifier: 2018_Su_Gonsoulin_fsu_0071E_14741
Format: Thesis

Title: Design and Implementing Multipurpose Sensor Network for Smart City Monitoring.
Creator: Cai, Donglin, Arghandeh, Reza, Pamidi, Sastry V., Foo, Simon Y., Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Abstract/Description: Weather and Air quality monitoring are very important aspects of smart city management. As population increase in the cities, the emission of pollutants includes Carbone Monoxide, Nitrogen Dioxide, Ozone and the Particulate matter will increase which will cause health and environmental issue. This paper is about developing a low-cost Urban sensors box based on Internet of Things. The Urban box is equipped with 4G/3G wireless communication which allows the wide range of mobility around the...
Show moreWeather and Air quality monitoring are very important aspects of smart city management. As population increase in the cities, the emission of pollutants includes Carbone Monoxide, Nitrogen Dioxide, Ozone and the Particulate matter will increase which will cause health and environmental issue. This paper is about developing a low-cost Urban sensors box based on Internet of Things. The Urban box is equipped with 4G/3G wireless communication which allows the wide range of mobility around the city. The Urban Sensor box is a collaborative work to monitor real-time data of the city’s environment, infrastructure, and activities. All these data will be provided to understand the interconnected behavior of different tangible networks of the urban environment.
Show less
Date Issued: 2018
Identifier: 2018_Su_CAI_fsu_0071N_14789
Format: Thesis

Title: Sensor Fault Detection and Isolation in Power Systems.
Creator: Yang, Huawei, Edrington, Christopher S., Ordóñez, Juan Carlos, Moss, Pedro L., Foo, Simon Y., Florida State University, College of Engineering, Department of Electrical and...
Show moreYang, Huawei, Edrington, Christopher S., Ordóñez, Juan Carlos, Moss, Pedro L., Foo, Simon Y., Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: In large-scale power systems, the integration of intelligent monitoring system increases the system resiliency and the control robustness. For example, sensor monitoring allows to automatically supervise the health of sensors and detect sensor failures without relying on hardware redundancy, and hence, it will further reduce the cost of monitoring systems in power systems. Sensor failure is critical in smart grids, where controllers rely on healthy measurements from different sensors to...
Show moreIn large-scale power systems, the integration of intelligent monitoring system increases the system resiliency and the control robustness. For example, sensor monitoring allows to automatically supervise the health of sensors and detect sensor failures without relying on hardware redundancy, and hence, it will further reduce the cost of monitoring systems in power systems. Sensor failure is critical in smart grids, where controllers rely on healthy measurements from different sensors to determine all kinds of operations. Current literature review shows that most of the researchers focus on control and management side of smart grids, assuming the information control centers or agencies get from sensors is accurate. However, when sensor failure happens, missing data and/or bad data can flow into control and management systems, which may lead to potential malfunction or even power system failures. This brings the need for Sensor Fault Detection and Isolation (SFDI), to eliminate this potential threat. The integration of the SFDI into monitoring systems will allow avoiding the contingencies due to fault data, and therefore increases the system resiliency and the control robustness. Hardware redundancy is the common solution for SFDI. By placing multiple sensors in the same position, the control center can then rely on redundant sensors when one is broken or inaccurate. Apparently, this method will increase the cost significantly when applying to large power systems. Analytical redundancy, on the contrary, a quantitative method built from power system models, is a more promising solution. It does not necessarily require hardware redundancy and hence can lower the cost. With an appropriate number of sensors placed in strategic locations, the algorithm can then automatically detect sensor failures without the need of extra redundant sensors. Furthermore, SFDI together with intelligent sensor optimization and placement will also facilitate the transfer of conventional central grid control to distributed decision making agencies with minimum computation and communication burden for each branch, and thus, it will enhance the system performance and resiliency. In this dissertation, a comprehensive review over the state-of-the-art FDI methodologies is given at first, then a proposed algorithm to determine the optimal location of computation agents is introduced, which serves as a guide for the SFDI algorithm implementation explained right after. The results of the algorithms indicated promising application in power system monitoring.
Show less
Date Issued: 2018
Identifier: 2018_Su_Yang_fsu_0071E_14730
Format: Thesis

Title: Control of Legged Robotic Systems: Substantiation of Gait Design, Multi-Modal Behaviors, and Dynamic Scaling Theory in Practice.
Creator: Blackman, Daniel J., Clark, Jonathan E., Oates, William, Moore, Carl A., Florida State University, College of Engineering, Department of Mechanical Engineering
Abstract/Description: Through limb structure and neuromuscular control, animals have demonstrated the ability to navigate obstacles and uneven terrain using a variety of different mechanisms and behaviors. Learning from the capabilities of animals, it is possible to develop robotic platforms that can aid in the study of these motions towards the production of new technologies for military, search and rescue, and medical applications. To produce these systems, it is important to first understand the underlying...
Show moreThrough limb structure and neuromuscular control, animals have demonstrated the ability to navigate obstacles and uneven terrain using a variety of different mechanisms and behaviors. Learning from the capabilities of animals, it is possible to develop robotic platforms that can aid in the study of these motions towards the production of new technologies for military, search and rescue, and medical applications. To produce these systems, it is important to first understand the underlying dynamics and design principles existent in nature that afford creatures such dexterous and agile movements. The creation of robots with legs provide a means for studying different aspects of the dynamics of legged locomotion. This includes investigations of limb coordination for gait controller design, the role of passive compliance in dynamic running, mechanical leg design and configuration for optimal energetic output, and scalability of legged systems in both simulation and through experimentation. This thesis aims to provide insight into the design and implementation of terrestrial robotic platforms with legs.
Show less
Date Issued: 2018
Identifier: 2018_Su_Blackman_fsu_0071N_14797
Format: Thesis

Title: An Isolated Modular Multilevel Multifunctional DC/DC Converter Based Battery Energy Storage System with Enhanced Fault Performance.
Creator: Mo, Ran, Li, Hui, Ordóñez, Juan Carlos, Lipo, T. A., Edrington, Christopher S., Steurer, Michael, Florida State University, College of Engineering, Department of Electrical and...
Show moreMo, Ran, Li, Hui, Ordóñez, Juan Carlos, Lipo, T. A., Edrington, Christopher S., Steurer, Michael, Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: Nowadays the medium-voltage dc system (MVDC) has been proposed in the renewable energy collector fields, long distance power transmission, small-scale industrial networks and all-electric shipboards due to its relatively higher efficiency, higher flexibility and lower cost in certain applications compared to the ac grid. Batteries offer scalable energy storage solutions in these applications for high-power and long-term energy demands with high energy density. Batterers play an essential role...
Show moreNowadays the medium-voltage dc system (MVDC) has been proposed in the renewable energy collector fields, long distance power transmission, small-scale industrial networks and all-electric shipboards due to its relatively higher efficiency, higher flexibility and lower cost in certain applications compared to the ac grid. Batteries offer scalable energy storage solutions in these applications for high-power and long-term energy demands with high energy density. Batterers play an essential role to smooth the power fluctuations and stabilize the grid as well. As the interface between battery energy storage and MVDC bus, the battery energy storage system (BESS) converter is a key enabling technology with specific requirements. Due to the lack of mature dc circuit breakers, the BESS converter is desired to achieve superior dc fault response which benefits the MVDC system reliability and resiliency. In addition, considering the high expenses and limited lifetime of nowadays battery products, multiple services and functions are preferred for BESS. In this research, the isolated modular multilevel dc/dc converter (iM2DC) based BESS is proposed. It can achieve both fault current limiting and fault ride through functions with direct dc current control capability, so it is possible to maintain the system operation during fault to ensure fault localization and fast recovery. Besides, via the virtual impedance method, the proposed topology employs the converter cell capacitors rather than batteries to provide the ripple energy to achieve the active power filter (APF) function, which allows the energy storage system to improve MVDC system power quality without consuming battery lifetime or extra circuits. In addition, since the medium-frequency transformer operation frequency can be as high as the converter switching frequency, the whole system power density will be improved. A controller hardware-in-the-loop testbed, which consists of the iM2DC based BESS model simulated in the real-time digital simulator (RTDS) and the multifunctional control programmed in the ABB controller products, is utilized to validate the functionality of proposed technology. Furthermore, the system efficiency of proposed BESS is not most optimized with the sinusoidal modulation. Therefore, in this research, a novel phase-shifted square wave modulation strategy is proposed for iM2DC. Compared to the conventional modulation methods, the proposed technique achieves reduced dc inductance due to higher equivalent switching frequency. In addition, the required capacitor energy can be minimized, which decreases the capacitor size without sacrificing the total device rating. Detailed principles of the proposed modulation and passive components design are presented. A downscaled 2kW prototype is built in the lab and the experimental results are provided to demonstrate the proposed modulation strategy. Finally the dissertation work is summarized and the scope of future work is discussed.
Show less
Date Issued: 2017
Identifier: 2018_Sp_Mo_fsu_0071E_14211
Format: Thesis

Title: Intelligent Energy and Operation Management of AC, DC and Hybrid Microgrids Based on Evolutionary Techniques.
Creator: Papari, Behnaz, Edrington, Christopher S., Clark, Jonathan E., Pamidi, Sastry V., Moss, Pedro L., Florida State University, College of Engineering, Department of Electrical and...
Show morePapari, Behnaz, Edrington, Christopher S., Clark, Jonathan E., Pamidi, Sastry V., Moss, Pedro L., Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: Intelligent energy management systems (EMSs) play pivotal roles for microgrids (MGs). The integration of distributed generators (DGs), energy storage devices (ESDs), electrical vehicles (EVs), and flexible loads in a large-scale system of interconnected MGs needs a local management and control platforms to avoid probable integration issues. Most of the small scale aforementioned components are operated in low voltage (LV) power networks which require optimal strategies to achieve sufficient...
Show moreIntelligent energy management systems (EMSs) play pivotal roles for microgrids (MGs). The integration of distributed generators (DGs), energy storage devices (ESDs), electrical vehicles (EVs), and flexible loads in a large-scale system of interconnected MGs needs a local management and control platforms to avoid probable integration issues. Most of the small scale aforementioned components are operated in low voltage (LV) power networks which require optimal strategies to achieve sufficient performance to operate interconnected to other MGs and upstream networks. Thus, an active energy management strategy is required for off and on grid modes of terrestrial and shipboard MGs to satisfy all demands and minimize unwanted outcomes. Due to the high penetration of renewable energy sources (RESs) and their output fluctuations in MGs, stochastic analysis besides deterministic should be considered to reduce the uncertainty effects of RESs based on their probabilistic nature. Robust EMSs are needed to diminish prediction errors and improve the reliability of power supplies in hybrid and interconnected MGs. Nevertheless, qualified approach to fulfill EMS for LV MGs in the large-scale will be challenging in both grid operation modes. Optimization modules into tertiary management layer have considered as a potential solution in order to actualize control strategy of the terrestrial or ship MGs with different types of practical constraints. However, each of these methods not only yield benefits but also bring new challenges related to their shortage. Different approaches have been considered to fulfill the EMS requirements of MGs. A large amount of literature focuses on the management strategy of MG in an off-line manner rather than multiple MGs which interact with each other and an upstream network in an on-line manner. In addition, the most commonly used optimization modules in EMSs do not meet the computational burden and convergence capability trade-off required for real-time applications. This report proposes a heuristic optimization approach for distributed control and management of hybrid MGs for real-time requirements. The Crow Search Algorithm (CSA) offers a superior method to move traditional non-linear optimization approaches since its fewer control parameters permit a rapid response compared to other search approaches. Moreover, a distributed fashion CSA (DCSA) is implemented to fulfill linear and non-linear solver requirements of real-time EMSs for hybrid power distribution system.
Show less
Date Issued: 2018
Identifier: 2018_Sp_Papari_fsu_0071E_14436
Format: Thesis

Title: Component Analysis-Based Change Detection for Sea Floor Imagery and Prelude to Sea-Surface Object Detection.
Creator: G-Michael, Tesfaye, Roberts, Rodney G., Meyer-Bäse, Anke, Meyer-Baese, U., Foo, Simon Y., Florida State University, College of Engineering, Department of Electrical and Computer...
Show moreG-Michael, Tesfaye, Roberts, Rodney G., Meyer-Bäse, Anke, Meyer-Baese, U., Foo, Simon Y., Florida State University, College of Engineering, Department of Electrical and Computer Engineering
Show less
Abstract/Description: In undersea remote sensing change detection is the process of detecting changes from pairs of multi-temporal sonar images of the seafloor that are surveyed approximately from the same location. The problem of change detection, subsequent anomaly feature extraction, and false alarms reduction is complicated due to several factors such as the presence of random speckle pattern in the images, variability in the seafloor environmental conditions, and platform instabilities. These complications...
Show moreIn undersea remote sensing change detection is the process of detecting changes from pairs of multi-temporal sonar images of the seafloor that are surveyed approximately from the same location. The problem of change detection, subsequent anomaly feature extraction, and false alarms reduction is complicated due to several factors such as the presence of random speckle pattern in the images, variability in the seafloor environmental conditions, and platform instabilities. These complications make the detection and classification of targets difficult. This thesis presents the first successful development of an end-to-end automated seabed change detection using multi-temporal synthetic aperture sonar (SAS) imagery that include a false detection/false alarms reduction based on principal and independent component analysis (PCA/ICA). ICA is a well-established statistical signal processing technique that aims to decompose a set of multivariate signals, i.e., SAS images, into a basis of statistically independent data-vectors with minimal loss of information content. The goal of ICA is to linearly transform the data such that the transformed variables are as statistically independent from each other as possible. The changes in the scene are detected in reduced second or higher order dependencies by ICA. Thus removing dependencies will leave the change features that will be further analyzed for detection and classification. Test results of the proposed method on a data set of SAS images (snippets) of declared changes from an automated change detection (ACD) process will be presented. These results illustrate the effectiveness of component analysis for reduction of false alarms in ACD process. In the context of sea surface object detection, this thesis investigates bistatic radar engagement using synthetic aperture radar (SAR) and examines five models of the bistatic electromagnetic scattering that will support future research on SAR sea-surface change detection.
Show less
Date Issued: 2017
Identifier: 2018_Sp_GMichael_fsu_0071E_14301
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

Electrical engineering (44)	+ -
Engineering (29)	+ -
Mechanical engineering (28)	+ -
Chemical engineering (18)	+ -
Aerospace engineering (17)	+ -

Materials science (16)	+ -
Civil engineering (13)	+ -
Industrial engineering (12)	+ -
Biomedical engineering (10)	+ -
Computer science (6)	+ -
Force and energy (6)	+ -
Planning (6)	+ -
Transportation (6)	+ -
Environmental engineering (5)	+ -
Acoustics (4)	+ -
Computer engineering (4)	+ -
Robotics (4)	+ -
Nanotechnology (3)	+ -
Applied mathematics (2)	+ -
Artificial intelligence (2)	+ -
Chemistry (2)	+ -
Chemistry, Organic (2)	+ -
Geotechnical engineering (2)	+ -
Low temperatures (2)	+ -
Physics (2)	+ -
Plasma (Ionized gases) (2)	+ -
Plastics (2)	+ -
Sustainability (2)	+ -
Biochemistry (1)	+ -
Biology (1)	+ -

text (154)	+ -
doctoral thesis (44)	+ -
master thesis (26)	+ -

Florida State University (154)	+ -
Department of Electrical and Computer Engineering (46)	+ -
Department of Mechanical Engineering (39)	+ -
Department of Chemical and Biomedical Engineering (25)	+ -
Department of Civil and Environmental Engineering (21)	+ -

Department of Industrial and Manufacturing Engineering (18)	+ -
Foo, Simon Y. (18)	+ -
Edrington, Christopher S. (16)	+ -
Li, Hui (16)	+ -
Andrei, Petru (14)	+ -
Guan, Jingjiao (14)	+ -
Taira, Kunihiko (14)	+ -
Alvi, Farrukh S. (13)	+ -
Cattafesta, Louis N. (11)	+ -
Hallinan, Daniel T. (11)	+ -
Kumar, Rajan (11)	+ -
Moss, Pedro L. (11)	+ -
Oates, William (11)	+ -
Vanli, Omer Arda (11)	+ -
Li, Yan (10)	+ -
Ozguven, Eren Erman (10)	+ -
Sobanjo, John Olusegun (10)	+ -
Zheng, Jianping P. (10)	+ -
Clark, Jonathan E. (8)	+ -
Jung, Sungmoon (8)	+ -
Liang, Zhiyong Richard (8)	+ -
Ordóñez, Juan Carlos (8)	+ -
Park, Chiwoo (8)	+ -
Roberts, Rodney G. (8)	+ -

Search In

Pages

Pages

Sort Results By:

Narrow results by:

Collection

Topical Subject

Genre

Type of Resource

Language

Creator

Owner