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Item Architectures and control for energy storage systems with wired and wireless power transfer(University of Alabama Libraries, 2019) Cao, Yuan; Abu Qahouq, Jaber; University of Alabama TuscaloosaShow more In the past two decades, the performance of battery energy storage systems (BESS) has been significantly improved with the utilization of advanced architectures and control methods and new electronic devices. However, the increasing demands imposed by BESS applications still necessitate the need for additional performance improvement and/or create new issues that need to be addressed. These can be summarized as follows: (1) The imbalance in the state-of-charge (SOC) between cells might occur, which might degrade the performance of the battery system. (2) In a BESS, with the increasingly advanced functions and control methods, the number of required components is increased. (3) In electrical vehicles (EVs) applications, the limited driving range and the needed charging time of the lithium-ion (Li-Ion) battery pack is one of the major reasons slowing down the adoption of EVs. (4) The transmission efficiency of wireless power transfer (WPT) systems is decreased as the distance and misalignment between transmitter (Tx) and receiver (Rx) increase. (5) In order to realize the wireless power transfer in BESS, additional components such as DC-AC inverter Tx coil, Rx coil and AC-DC rectifier are required, which increase the cost and size of the system. This dissertation work focuses on investigating the challenges mentioned above to further improve the overall performance of battery system, reduce the number of components and converters, increase the system efficiency and realize a robust and cost-effective battery energy storage system. Chapter 2 and Chapter 3 focus on the challengers related to SOC balancing and large number of components in battery systems. In Chapter 4, one unique aspect of the WEDES system is used in order to add flexibility and improve safety. Chapter 5 and Chapter 6 address the challenge related to decreased transmission efficiency in wireless power transfer when charging a battery. In Chapter 7, in order to deal with the challenge that additional components are required to realize wireless power transfer, a single dual-type-output power converter is discussed and analyzed. Chapter 8 provides a summary and conclusion for the work presented in this dissertation and discusses some potential future work.Show more Item Confined Tube Aeration System for Aquaculture and Wastewater Industries(University of Alabama Libraries, 2023) Mahmud, Roohany; Woodbury, KeithShow more This dissertation proposes a novel bubble-based aeration system known as 'Confined Tube Aeration (CTA)', which uses a Venturi injector as the bubble generation device and connects to a coiled pipe network after the Venturi outlet as a mixing chamber where the air-water mass transfer occurs. In this work, to analyze the effectiveness of this proposed system, several experiments are conducted, and numerical (Discrete Bubble Model) analyses are also performed to optimize the system performance. A lab-scale simple CTA system is built using a single pump, one 1-inch Venturi, and a coiled pipe network, and experiments are conducted to analyze its performance. Results from the numerical model also conform well with experimental results. Two sizes of Venturi injectors, 1-inch and 4-inch, are investigated numerically to identify their performances in a CTA system. Suction air flow, bubble size, volume fractions, and injector efficiency are also analyzed. The 4-inch injector is found to perform better in terms of oxygen transfer rate and per unit of power requirement for that specific oxygen transfer rate at standard conditions. CTA system with multiple injectors arranged in parallel connections is also studied. Experimental data show that the 2-injector system performs better than the 1-injector and 3-injector systems. When pump speed is slowed down using a VFD, the performance of the 1-injector system is greatly improved. It is also observed that, at a larger-sized CTA tube, the mass transfer efficacy is improved, and SAE also improves as the pump's hydraulic energy input remains constant. An additional benefit of this proposed technology is its simplistic design which may incur reduced installation and maintenance costs compared to the existing porous bubble diffuser and mechanical aerator system. This proposed technology can be easily retrofitted to the existing aeration system without requiring large-scale modifications of the treatment plant's aeration techniques. Additionally, the flexibility of this system to build outside of the aeration tank can be considered for retrofitting in existing treatment plants. Aquaculture can specifically benefit from this technology as it does not require a deep aeration pond for the bubbles to transfer oxygen to the water.Show more Item Coupled Flexural-Torsional Vibration Analysis of a Double-Cantilever Structure for Nanomaching Application(University of Alabama Libraries, 2021) Zargarani, Anahita; Mahmoodi, Nima; University of Alabama TuscaloosaShow more This dissertation aims to investigate the coupled flexural-torsional vibrations of a piezoelectrically-actuated double-cantilever structure for nanomachining applications. The structure of interest consists of two identical Euler-Bernoulli cantilever beams connected by a rigid tip connection at their free ends. The double-cantilever structure in this study vibrates in two distinct modes: flexural mode or coupled flexural-torsional mode. The flexural mode refers to the in-phase flexural vibrations of the two cantilever beams resulting in transverse motion of the tip connection, while the coupled flexural-torsional mode refers to the coupled flexural-torsional vibrations of the cantilever beams resulting in the rotational motion of the tip connection. The latter is the main interest of this research. The governing equations of motion and boundary conditions are developed using Hamilton’s principle. Two uncoupled equations are found for each beam: one corresponding to the flexural vibrations and the other one corresponding to the torsional vibrations of the cantilever beam. The characteristic equations for both the flexural and the coupled flexural-torsional vibration modes are derived and solved to find the corresponding natural frequencies. The orthogonality condition among the mode shapes is derived and utilized to determine the modal coefficients corresponding to each mode of vibration. The time response to the forced vibrations of the structure is found using the Galerkin approximation method. The effects of the dimensional parameters, including the length of the cantilever beams and the length of the tip connection, and the piezoelectric input voltage on the natural frequencies and the amplitude of vibrations of the structure are analyzed. An experimental setup consisting of a piezoelectric double-cantilever structure is designed and utilized to verify the analytical results. First, the coupled flexural-torsional fundamental frequencies of the structure with various configurations are obtained experimentally, which are in good agreement with the analytically-determined values. Moreover, the experimental results verify the analytical results stating that the natural frequencies of the structure decrease as either the length of the cantilever beams or the length of the tip connection is increased. Next, the amplitudes of the coupled flexural-torsional vibrations of different configurations of the structure excited at their natural frequencies with a range of input voltages are obtained. The results of the effect of the dimensional parameters and the piezoelectric input voltage on the angle of rotation of the tip connection are presented.Show more Item Determination of Multi-Mode Component Failure and Time-To-Failure with Machine Learning and Deep Learning(University of Alabama Libraries, 2023) O'Donnell, John Lewis; Yoon, Hwan-SikShow more A hybrid deep learning and machine learning approach for both failure mode classification and time-to-failure prediction is proposed in this dissertation, with a focus on a multi-mode failure regime where the state of health of components can vary. To validate the potential performance of the proposed approach, a vehicle's leaking hydraulic suspension system is simulated via a quarter car model as a proof of concept. Next, the quarter car model is expanded to include a model of a failing engine mount. The dynamic data from these models is employed to train a NARX net with the health condition and degradation rate as an output. The predictive capabilities of the NARX given this data is significant, validating the proposed approach. To develop the hybrid approach, a four-cylinder diesel engine with EGR and VGT is simulated over a prescribed operational range for four failure types. A multi-label CNN model is utilized to classify which multi-mode failure modes are occurring while hiding health condition information. The approach resulted in significant performance in classifying the failure modes. This data is then employed in regression models to determine the health condition of various components. It was determined that utilizing this data and previous state information with ensemble tree methods and neural networks results in predictive accuracy with less than 3% normalized root mean square error. Finally, a NARX net approach for determining the degradation rate and time-to-failure of a component utilizing this health condition information is verified. A discussion on how these approaches can be combined to create a hybrid predictive model that determines the engine's probable failing time is presented. Based on the results from each stage of the hybrid model, it is expected that this approach can provide significant predictive performance in monitoring the health of a diesel engine as well as any similar system with comparable failure modes.Show more Item Game Theory Applications in Astrodynamics and Space Domain Awareness(University of Alabama Libraries, 2021) Schoenwetter, Luke; Sood, Rohan; University of Alabama TuscaloosaShow more As the number of nations possessing space launch capabilities increases, Earth orbit inherently becomes a competitive environment. Furthermore, each competing agent possesses unique objectives that may or may not align with the objectives of other agents. The competitive dynamics presented by this system are well suited for the application of game theory: the study of rational competitors from a mathematical perspective. The presented work combines the disciplines of game theory, optimal control, and astrodynamics to form generic game solution methods. These solution methods are used to obtain optimal open-loop strategies for an interceptor and an evasive target. A game involving an interceptor, a defender, and a ballistic target is also studied. Parameter space analyses are performed across a wide range of initial conditions to identify and visualize trends in the solution spaces. Additionally, a framework for testing strategies in a closed-loop format is developed to evaluate the consequences of sub-optimal actions. The various trends and characteristics found in the solution spaces are discussed, as is the relevancy of the results to modern space security and contingency planning.Show more Item HVAC control loop performance assessment: A critical review (1587-RP)(Taylor & Francis, 2016) O'Neill, Zheng; Li, Yanfei; Williams, Keith; University of Alabama TuscaloosaShow more This article presents a comprehensive review of control loop performance assessments in the context of building HVAC controls. Few studies are available for assessing HVAC control loop performance using a single control quality factor. A control quality factor should be an objective and quantitative metric with simple-to-interpret criteria and should only use data available from the actual control system, such as the control output. The authors systematically reviewed 34 indices and the associated methods of evaluating control loop performance and cataloged the drawbacks and merits of the different indices. Most of these performance assessment indices are currently used in process control industry applications. There were 14 of the 34 indices selected for further review, due to their particular suitability for implementation in HVAC control loop performance assessment. Finally, the selected 14 indices are implemented for assessments of three regulatory control loops with proportional-integral controllers: a heating coil outlet air temperature control loop and variable air volume room air temperature control loop using simulated data from a dynamic Modelica model, and variable air volume room air temperature control loop in a heating mode from real field data. Based on the review and preliminary results, the Normalized Harris Index and exponentially weighted moving averages based index are proposed as potential candidates for control quality factor, and further investigation of the use of them in HVAC control loop performance assessment is recommended.Show more Item Hybrid Electric Vehicle Powertrain Control Based on Machine Learning(University of Alabama Libraries, 2022) Yao, Zhengyu; Yoon, Hwan-Sik; University of Alabama TuscaloosaShow more Due to increased environmental and economic considerations, energy-efficient vehicles such as Hybrid Electric Vehicles (HEVs) have received great attention from the general public as well as automotive research community. HEVs achieve better fuel economy than conventional vehicles by employing two different power sources: a mechanical engine and an electrical motor. By controlling the two power sources optimally based on the current system state under different driving conditions, they can achieve much improved fuel economy compared to conventional vehicles powered by internal combustion engines only. These power sources have conventionally been controlled by rule-based or optimization-based control algorithms. Rule-based algorithms utilize a well-defined and easy-to-understand control logic while optimization-based control algorithms employ a mathematical function that is minimized by a controller during the vehicle operation. Besides these two conventional approaches, recent advancements in machine learning offer new opportunities in optimal control of multiple power sources in unprecedent ways. Therefore, in order to investigate benefits offered by the new machine learning-based powertrain control paradigm, different machine learning approaches are studied for a HEV in this dissertation.Show more Item A kinematic analysis of a stacked planar compliant tensegrity mechanism(University of Alabama Libraries, 2019) Tanouye, Miranda; Vikas, Vishesh; University of Alabama TuscaloosaShow more tensile members (strings). Compliant tensegrity mechanisms (CoTM) introduce springs alongside strings and rods, allowing these structures to be more adaptable and robust. The kinematic and stability analyses of such mechanisms will facilitate better behavioral understanding for control of such structures. Such structures are known to display nonlinear behaviors including multiple equilibria. Previously, a simple planar model of such a CoTM has been studied. This can be furthered upon by viewing the mechanism as a single link within a kinematic chain. However, a nomenclature methodology for kinematic chain of CoTM modules is lacking. The equilibrium analysis of CoTM is non-trivial as the equilibrium equations are nonlinear in variables (angles occuring as sine and cosine). Mathematically, for a small number of equations, the solutions can be obtained using polynomial elimination methods. The computational complexity increases exponentially with the number of equations along with the number of equilibrium solutions. The presented work analyzes single module and chain of planar CoTM comprising of two rigid bodies connected by a rigid link and two springs through revolute joints. The computational complexity of a planar CoTM link increases drastically as the zero free-length (ZFL) constraint of the springs in relaxed. Stability of the solutions is evaluated by observing the eigenvalues of the Jacobian of the equilibrium equations. After analyzing the system for one link, a two-link chain system is analyzed. Analysis is done based on knowledge gained from analyzing a single link and solving for all solutions of the mechanism and then determining stability of the found equilibrium solutions.Show more Item Novel Self-Actuated Long Travel Linear Actuator(University of Alabama Libraries, 2022) Dooley, Mason; Shen, Xiangrong; University of Alabama TuscaloosaShow more A variety of linear actuation technologies are presently available on the market or are readily manufacturable. Each of these technologies represents a series of compromises between various mechanical capabilities. One combination of these characteristics that is not readily available is a self-contained actuator capable of long travel, that is easily manufacturable, and controllable. An actuator of this type would be particularly well suited for use in assistive technologies such as stair lifts. The research in this thesis outlines the development of a novel actuator that fits these criteria and evaluates the properties of such an actuator. This actuator functions through the interaction of a double-sided timing belt and a custom slotted linear rack. These provide the force transfer elements of the actuator and represent the primary novelty of the design. As such the double-sided timing belt-based self-powered linear actuator (DSTB-SPLA) is designed from the timing belt and rack outward. The DSTB-SPLA drive train is designed with considerations for smooth operation of the belt-rack interface as well as the maximum mechanical and electrical loading of the system. The control and sensing electronics are selected and embedded into the system to provide a refresh rate high enough for feedback-based control. A PID controller and a model-based SMC controller are each applied to the DSTB-SPLA and evaluated based on control system metrics. Finally, the mechanical efficiency and the maximum loading of the DSTB-SPLA are experimentally determined to provide a measure of the mechanical characteristics of the actuator.Show more Item State-of-health diagnosis of lithium-ion battery systems and health-based control(University of Alabama Libraries, 2021) Xia, Zhiyong; Abu Qahouq, Jaber; University of Alabama TuscaloosaShow more Lithium-ion batteries are widely used in battery energy storage systems (BESS) because of their unique advantages, such as high energy density. State-of-health (SOH) estimation, as a critical function of a battery management system (BMS), is important to improve the safety and reliability of lithium-ion BESS. One objective of this dissertation is to develop fast and accurate SOH estimation methods to overcome shortcomings of conventional methods, such as slow estimation speed. Another main objective of this dissertation is to develop battery health-based control algorithms that utilize the output of SOH estimators. Chapter 1 presents an introduction to BESS and BMS and a literature review. It points out the challenges and importance of developing SOH estimation methods with improved performance such as speed and battery health-based SOC balancing control algorithms. Chapter 2 discusses the development of an in-house autonomous battery ageing platform. The developed platform can age a battery autonomously while obtaining and recording experimentally measured data of interest to support battery health diagnosis investigation and research. Chapter 3 analyzes the aggregated battery ageing data collected from the developed autonomous battery ageing platform. Several distinctive SOH indicators are identified to reflect the degradation level of battery to support the development of SOH estimators. Chapter 4 focuses on the development of power electronics based real-time online complex impedance spectrum measurement methods. These developed measurement methods support the development of online impedance based SOH estimators which provide fast SOH estimation for battery cells. In chapter 5, the correlations between the identified SOH indicators presented in chapter 3 and the SOH values of battery cells are utilized to develop deep neural network (DNN) based SOH estimators. It is observed that the diversity of SOH indicators used as the input of DNN can substantially improve estimation performance. Chapter 6 presents a battery health based SOC balancing control method. The presented method allows for drawing energy from battery cells intelligently based on the SOH differences among different battery cells, which helps to improve energy utilization efficiency and reliability of BESS. Chapter 7 concludes the research work presented in this dissertation and discusses potential future research.Show more Item Synthesis and Analysis of Tensegrity Mechanisms(University of Alabama Libraries, 2021) Gotberg, Clayton Russell; Vikas, Vishesh; University of Alabama TuscaloosaShow more Tensegrity systems combine antagonistic tensile and compressive members. The computational cost of synthesis and form-finding greatly increases with the complexity of a tensegrity structure. One solution, the use of modules which can be combined to create a more complex structure (tensegrity primitives), has been investigated using highly symmetric primitives of a few canonical types. This thesis determines the multistable region of an example planar tensegrity-adjacent mechanism, measures the feasibility of various parameters for shape control and demonstrates a method for stacking any number of such mechanisms, then develops a search method which exhaustively determines all possible tensegrities with a specified cable graph and with varying additional constraints. To demonstrate the viability of these methods, full catalogues of tensegrity primitives for a host of simple cable graphs are generated.Show more