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Title: Multi-level Optimization and Applications with Non-Traditional Game Theory.
Creator: Yun, Guanxiang, Zheng, Qipeng, Boginski, Vladimir, Karwowski, Waldemar, Yong, Jiongmin, University of Central Florida
Abstract / Description: We study multi-level optimization problem on energy system, transportation system and information network. We use the concept of boundedly rational user equilibrium (BRUE) to predict the behaviour of users in systems. By using multi-level optimization method with BRUE, we can help to operate the system work in a more efficient way. Based on the introducing of model with BRUE constraints, it will lead to the uncertainty to the optimization model. We generate the robust optimization as the...
Show moreWe study multi-level optimization problem on energy system, transportation system and information network. We use the concept of boundedly rational user equilibrium (BRUE) to predict the behaviour of users in systems. By using multi-level optimization method with BRUE, we can help to operate the system work in a more efficient way. Based on the introducing of model with BRUE constraints, it will lead to the uncertainty to the optimization model. We generate the robust optimization as the multi-level optimization model to consider for the pessimistic condition with uncertainty. This dissertation mainly includes four projects. Three of them use the pricing strategy as the first level optimization decision variable. In general, our models' first level's decision variables are the measures that we can control, but the second level's decision variables are users behaviours that can only be restricted within BRUE with uncertainty.
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Date Issued: 2019
Identifier: CFE0007881, ucf:52758
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007881

Title: THE LAST 2500 YEARS: DEFINING, DISSECTING AND DIRECTING THE LESS LINEAR MUSICAL.
Creator: Lewis, Andrew, Weaver, Earl, University of Central Florida
Abstract / Description: Since the first recorded theatrical events, theatre has been presented in a linear fashion. It is no surprise that the majority of American Musical Theatre also follows a linear plot conception. Musicals that blatantly defy linearity are often called Ã‚Â"conceptÃ‚Â" musicals. However, there is a small portion of concept musicals that do not abandon their linear plot altogether, but instead choose to skew the line in order to give the audience a unique...
Show moreSince the first recorded theatrical events, theatre has been presented in a linear fashion. It is no surprise that the majority of American Musical Theatre also follows a linear plot conception. Musicals that blatantly defy linearity are often called Ã‚Â"conceptÃ‚Â" musicals. However, there is a small portion of concept musicals that do not abandon their linear plot altogether, but instead choose to skew the line in order to give the audience a unique perspective of the story being told. This mass categorization does not accurately take into account the extreme difference in structure of the two types of concept musicals. For this purpose, I explored the notion of a new structural category, the Less Linear Concept Musical, in hopes of identifying the unique characteristics and challenges associated with this type of musical. Beginning with AristotleÃ‚Â's "The Poetics" and ending in modern day Musical Theatre, I examine key events in the shaping of this musical theatre form, as well as define the form itself. The application of this research culminated in a classroom presentation of Jason Robert BrownÃ‚Â's The Last Five Years, which I directed. I pose the question, Ã‚Â"Can sound direction conquer the pitfalls found within the Less Linear Concept Musical?Ã‚Â"
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Date Issued: 2010
Identifier: CFE0003361, ucf:48479
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003361

Title: CONAE MicroWave Radiometer (MWR) Counts to Brightness Temperature Algorithm.
Creator: Ghazi, Zoubair, Jones, W Linwood, Wei, Lei, Mikhael, Wasfy, Wu, Thomas, Junek, William, Piepmeier, Jeffrey, University of Central Florida
Abstract / Description: This dissertation concerns the development of the MicroWave Radiometer (MWR) brightness temperature (Tb) algorithm and the associated algorithm validation using on-orbit MWR Tb measurements. This research is sponsored by the NASA Earth Sciences Aquarius Mission, a joint international science mission, between NASA and the Argentine Space Agency (Comision Nacional de Actividades Espaciales, CONAE). The MWR is a CONAE developed passive microwave instrument operating at 23.8 GHz (K-band) H-pol...
Show moreThis dissertation concerns the development of the MicroWave Radiometer (MWR) brightness temperature (Tb) algorithm and the associated algorithm validation using on-orbit MWR Tb measurements. This research is sponsored by the NASA Earth Sciences Aquarius Mission, a joint international science mission, between NASA and the Argentine Space Agency (Comision Nacional de Actividades Espaciales, CONAE). The MWR is a CONAE developed passive microwave instrument operating at 23.8 GHz (K-band) H-pol and 36.5 GHz (Ka-band) H- (&) V-pol designed to complement the Aquarius L-band radiometer/scatterometer, which is the prime sensor for measuring sea surface salinity (SSS). MWR measures the Earth's brightness temperature and retrieves simultaneous, spatially collocated, environmental measurements (surface wind speed, rain rate, water vapor, and sea ice concentration) to assist in the measurement of SSS.This dissertation research addressed several areas including development of: 1) a signal processing procedure for determining and correcting radiometer system non-linearity; 2) an empirical method to retrieve switch matrix loss coefficients during thermal-vacuum (T/V) radiometric calibration test; and 3) an antenna pattern correction (APC) algorithm using Inter-satellite radiometric cross-calibration of MWR with the WindSat satellite radiometer. The validation of the MWR counts-to-Tb algorithm was performed using two years of on-orbit data, which included special deep space calibration measurements and routine clear sky ocean/land measurements.
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Date Issued: 2014
Identifier: CFE0005496, ucf:50366
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005496

Title: PHASE-SHIFTING HAAR WAVELETS FOR IMAGE-BASED RENDERING APPLICATIONS.
Creator: Alnasser, Mais, Foroosh, Hassan, University of Central Florida
Abstract / Description: In this thesis, we establish the underlying research background necessary for tackling the problem of phase-shifting in the wavelet transform domain. Solving this problem is the key to reducing the redundancy and huge storage requirement in Image-Based Rendering (IBR) applications, which utilize wavelets. Image-based methods for rendering of dynamic glossy objects do not truly scale to all possible frequencies and high sampling rates without trading storage, glossiness, or computational time,...
Show moreIn this thesis, we establish the underlying research background necessary for tackling the problem of phase-shifting in the wavelet transform domain. Solving this problem is the key to reducing the redundancy and huge storage requirement in Image-Based Rendering (IBR) applications, which utilize wavelets. Image-based methods for rendering of dynamic glossy objects do not truly scale to all possible frequencies and high sampling rates without trading storage, glossiness, or computational time, while varying both lighting and viewpoint. This is due to the fact that current approaches are limited to precomputed radiance transfer (PRT), which is prohibitively expensive in terms of memory requirements when both lighting and viewpoint variation are required together with high sampling rates for high frequency lighting of glossy material. At the root of the above problem is the lack of a closed-form run-time solution to the nontrivial problem of rotating wavelets, which we solve in this thesis. We specifically target Haar wavelets, which provide the most efficient solution to solving the tripleproduct integral, which in turn is fundamental to solving the environment lighting problem. The problem is divided into three main steps, each of which provides several key theoretical contributions. First, we derive closed-form expressions for linear phase-shifting in the Haar domain for one-dimensional signals, which can be generalized to N-dimensional signals due to separability. Second, we derive closed-form expressions for linear phase-shifting for two-dimensional signals that are projected using the non-separable Haar transform. For both cases, we show that the coefficients of the shifted data can be computed solely by using the coefficients of the original data. We also derive closed-form expressions for non-integer shifts, which has not been reported before. As an application example of these results, we apply the new formulae to image shifting, rotation and interpolation, and demonstrate the superiority of the proposed solutions to existing methods. In the third step, we establish a solution for non-linear phase-shifting of two-dimensional non-separable Haar-transformed signals, which is directly applicable to the original problem of image-based rendering. Our solution is the first attempt to provide an analytic solution to the difficult problem of rotating wavelets in the transform domain.
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Date Issued: 2008
Identifier: CFE0002214, ucf:47882
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002214

Title: A Flexible Physics-Based Lifing Method for Metals Under Creep and Thermomechanical Fatigue.
Creator: Irmak, Firat, Gordon, Ali, Catbas, Necati, Raghavan, Seetha, University of Central Florida
Abstract / Description: This thesis focuses on the development of a flexible, physics-based life prediction approach for steels under complex conditions. Low alloy steels continue to be the materials of choice for large turbomachinery structures experiencing high temperatures for long durations. There has been significant advancement in the research of modern alloys; furthermore, these materials are continue to be utilized in boilers, heat exchanger tubes, and throttle valve bodies in both turbomachinery and...
Show moreThis thesis focuses on the development of a flexible, physics-based life prediction approach for steels under complex conditions. Low alloy steels continue to be the materials of choice for large turbomachinery structures experiencing high temperatures for long durations. There has been significant advancement in the research of modern alloys; furthermore, these materials are continue to be utilized in boilers, heat exchanger tubes, and throttle valve bodies in both turbomachinery and pressure-vessel/piping applications. The material 2.25Cr-1Mo is studied in the present work. The resistance of this alloy to deformation and damage under creep and/or fatigue at elevated temperatures make it appropriate for structures required to endure decades of service. Also, this material displays an excellent balance of ductility, corrosion resistance, and creep strength under aggressive operating conditions. Both creep-fatigue (CF) and thermomechanical fatigue (TMF) have been the limiting factor for most turbine components fabricated from various alloys; therefore, a life prediction approach is constructed for simulating fatigue life for cases where the material is experiencing mechanical loading with thermal cycling. Flexibility is imparted to the model through its ability to emphasize the dominant damage mechanism which may vary among alloys. A material database is developed to improve and compare the model with experimental data. This database contains low cycle fatigue (LCF), creep fatigue (CF), and thermomechanical fatigue (TMF) experiments. Parameters for the model are obtained with regression fits with the support of a broad experimental database. Additionally, the cumulative damage approach, better known as Miner's rule, is used in this study as the fundamental method to combine damage mechanisms. Life predictions are obtained by the usage of a non-interacting creep-plasticity constitutive model capable of simulating not only the temperature- and rate-dependence.
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Date Issued: 2017
Identifier: CFE0006885, ucf:51731
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006885

Title: Batch and Online Implicit Weighted Gaussian Processes for Robust Novelty Detection.
Creator: Ramirez Padron, Ruben, Gonzalez, Avelino, Georgiopoulos, Michael, Stanley, Kenneth, Mederos, Boris, Wang, Chung-Ching, University of Central Florida
Abstract / Description: This dissertation aims mainly at obtaining robust variants of Gaussian processes (GPs) that do not require using non-Gaussian likelihoods to compensate for outliers in the training data. Bayesian kernel methods, and in particular GPs, have been used to solve a variety of machine learning problems, equating or exceeding the performance of other successful techniques. That is the case of a recently proposed approach to GP-based novelty detection that uses standard GPs (i.e. GPs employing...
Show moreThis dissertation aims mainly at obtaining robust variants of Gaussian processes (GPs) that do not require using non-Gaussian likelihoods to compensate for outliers in the training data. Bayesian kernel methods, and in particular GPs, have been used to solve a variety of machine learning problems, equating or exceeding the performance of other successful techniques. That is the case of a recently proposed approach to GP-based novelty detection that uses standard GPs (i.e. GPs employing Gaussian likelihoods). However, standard GPs are sensitive to outliers in training data, and this limitation carries over to GP-based novelty detection. This limitation has been typically addressed by using robust non-Gaussian likelihoods. However, non-Gaussian likelihoods lead to analytically intractable inferences, which require using approximation techniques that are typically complex and computationally expensive. Inspired by the use of weights in quasi-robust statistics, this work introduces a particular type of weight functions, called here data weighers, in order to obtain robust GPs that do not require approximation techniques and retain the simplicity of standard GPs. This work proposes implicit weighted variants of batch GP, online GP, and sparse online GP (SOGP) that employ weighted Gaussian likelihoods. Mathematical expressions for calculating the posterior implicit weighted GPs are derived in this work. In our experiments, novelty detection based on our weighted batch GPs consistently and significantly outperformed standard batch GP-based novelty detection whenever data was contaminated with outliers. Additionally, our experiments show that novelty detection based on online GPs can perform similarly to batch GP-based novelty detection. Membership scores previously introduced by other authors are also compared in our experiments.
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Date Issued: 2015
Identifier: CFE0005869, ucf:50858
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005869

Title: Biomechanical Factors Influencing Treatment of Developmental Dysplasia of the Hip (DDH) with the Pavlik Harness.
Creator: Ardila, Orlando, Kassab, Alain, Moslehy, Faissal, Divo, Eduardo, University of Central Florida
Abstract / Description: Biomechanical factors influencing the reduction of dislocated hips with the Pavlik harness in patients of Developmental Dysplasia of the Hip (DDH) were studied using a simplified three-dimensional computer model simulating hip reduction dynamics in (1) subluxated, and (2) fully dislocated hip joints. The CT-scans of a 6 month-old female infant were used to measure the geometrical features of the hip joint including acetabular and femoral head diameter, acetabular depth, and geometry of the...
Show moreBiomechanical factors influencing the reduction of dislocated hips with the Pavlik harness in patients of Developmental Dysplasia of the Hip (DDH) were studied using a simplified three-dimensional computer model simulating hip reduction dynamics in (1) subluxated, and (2) fully dislocated hip joints. The CT-scans of a 6 month-old female infant were used to measure the geometrical features of the hip joint including acetabular and femoral head diameter, acetabular depth, and geometry of the acetabular labrum, using the medical segmentation software Mimics. The lower extremity was modeled by three segments: thigh, leg, and foot. The mass and the location of the center of gravity of each segment were calculated using anthropometry, based on the total body mass of a 6-month old female infant at the 50th length-for-age percentile. A calibrated nonlinear stress-strain model was used to simulate muscle responses. The simplified 3D model consists of the pubis, ischium, acetabulum with labrum, and femoral head, neck, and shaft. It is capable of simulating dislocated as well as reduced hips in abduction and flexion.Five hip adductor muscles were identified as key mediators of DDH prognosis, and the non-dimensional force contribution of each in the direction necessary to achieve concentric hip reductions was determined. Results point to the adductor muscles as mediators of subluxated hip reductions, as their mechanical action is a function of the degree of hip dislocation. For subluxated hips in abduction and flexion, the Pectineus, Adductor Brevis, Adductor Longus, and proximal Adductor Magnus muscles contribute positively to reduction, while the rest of the Adductor Magnus contributes negatively. In full dislocations all muscles contribute detrimentally to reduction, elucidating the need for traction to reduce Graf IV type dislocations. Reduction of dysplastic hips was found to occur in two distinct phases: (a) release phase and (b) reduction phase.To expand the range of DDH-related problems that can be studied, an improved three-dimensional anatomical computer model was generated by combining CT-scan and muscle positional data belonging to four human subjects. This model consists of the hip bone and femora of a 10-week old female infant. It was segmented to encompass the distinct cartilaginous regions of infant anatomy, as well as the different regions of cortical and cancellous bone; these properties were retrieved from the literature. This engineering computer model of an infant anatomy is being employed for (1) the development of a complete finite element and dynamics computer model for simulations of hip dysplasia reductions using novel treatment approaches, (2) the determination of a path of least resistance in reductions of hip dysplasia based on a minimum potential energy approach, (3) the study of the mechanics of hyperflexion of the hip as alternative treatment for late-presenting cases of hip dysplasia, and (4) a comprehensive investigation of the effects of femoral anteversion angle (AV) variations in reductions of hip dysplasia. This thesis thus reports on an interdisciplinary effort between orthopedic surgeons and mechanical engineers to apply engineering fundamentals to solve medical problems. The results of this research are clinically relevant in pediatric orthopaedics.
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Date Issued: 2013
Identifier: CFE0004646, ucf:49907
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004646

Title: Ultra-Efficient Cascaded Buck-Boost Converter.
Creator: Ashok Pise, Anirudh, Batarseh, Issa, Mikhael, Wasfy, Sun, Wei, Kutkut, Nasser, University of Central Florida
Abstract / Description: This thesis presents various techniques to achieve ultra-high-efficiency for Cascaded-Buck-Boost converter. A rigorous loss model with component non linearity is developed and validated experimentally. An adaptive-switching-frequency control is discussed to optimize weighted efficiency. Some soft-switching techniques are discussed. A low-profile planar-nanocrystalline inductor is developed and various design aspects of core and copper design are discussed. Finite-element-method is used to...
Show moreThis thesis presents various techniques to achieve ultra-high-efficiency for Cascaded-Buck-Boost converter. A rigorous loss model with component non linearity is developed and validated experimentally. An adaptive-switching-frequency control is discussed to optimize weighted efficiency. Some soft-switching techniques are discussed. A low-profile planar-nanocrystalline inductor is developed and various design aspects of core and copper design are discussed. Finite-element-method is used to examine and visualize the inductor design. By implementing the above, a peak efficiency of over 99.2 % is achieved with a power density of 6 kW/L and a maximum profile height of 7 mm is reported. This converter finds many applications because of its versatility: allowing bidirectional power flow and the ability to step-up or step-down voltages in either direction.
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Date Issued: 2017
Identifier: CFE0007277, ucf:52181
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007277

Title: Semi-Analytical Solutions of Non-linear Differential Equations Arising in Science and Engineering.
Creator: Dewasurendra, Mangalagama, Vajravelu, Kuppalapalle, Mohapatra, Ram, Rollins, David, Kumar, Ranganathan, University of Central Florida
Abstract / Description: Systems of coupled non-linear differential equations arise in science and engineering are inherently nonlinear and difficult to find exact solutions. However, in the late nineties, Liao introduced Optimal Homotopy Analysis Method (OHAM), and it allows us to construct accurate approximations to the systems of coupled nonlinear differential equations.The drawback of OHAM is, we must first choose the proper auxiliary linear operator and then solve the linear higher-order deformation equation by...
Show moreSystems of coupled non-linear differential equations arise in science and engineering are inherently nonlinear and difficult to find exact solutions. However, in the late nineties, Liao introduced Optimal Homotopy Analysis Method (OHAM), and it allows us to construct accurate approximations to the systems of coupled nonlinear differential equations.The drawback of OHAM is, we must first choose the proper auxiliary linear operator and then solve the linear higher-order deformation equation by spending lots of CPU time. However, in the latest innovation of Liao's " Method of Directly Defining inverse Mapping (MDDiM)" which he introduced to solve a single nonlinear ordinary differential equation has great freedom to define the inverse linear map directly. In this way, one can solve higher order deformation equations quickly, and it is unnecessary to calculate an inverse linear operator.Our primary goal is to extend MDDiM to solve systems of coupled nonlinear ordinary differential equations. In the first chapter, we will introduce MDDiM and briefly discuss the advantages of MDDiM Over OHAM. In the second chapter, we will study a nonlinear coupled system using OHAM. Next three chapters, we will apply MDDiM to coupled non-linear systems arise in mechanical engineering to study fluid flow and heat transfer. In chapter six we will apply this novel method to study coupled non-linear systems in epidemiology to investigate how diseases spread throughout time. In the last chapter, we will discuss our conclusions and will propose some future work. Another main focus is to compare MDDiM with OHAM.
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Date Issued: 2019
Identifier: CFE0007624, ucf:52551
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007624

Title: Quantum Chemical Studies for the Engineering of Metal Organic Materials.
Creator: Rivera Jacquez, Hector, Masunov, Artem, Balaeff, Alexander, Harper, James, Heider, Emily, Zou, Shengli, Kaden, William, University of Central Florida
Abstract / Description: Metal Organic Materials (MOM) are composed of transition metal ions as connectors and organic ligands as linkers. MOMs have been found to have high porosity, catalytic, and optical properties. Here we study the gas adsorption, color change, and non-linear optical properties of MOMs. These properties can be predicted using theoretical methods, and the results may provide experimentalists with guidance for rational design and engineering of novel MOMs. The theory levels used include semi...
Show moreMetal Organic Materials (MOM) are composed of transition metal ions as connectors and organic ligands as linkers. MOMs have been found to have high porosity, catalytic, and optical properties. Here we study the gas adsorption, color change, and non-linear optical properties of MOMs. These properties can be predicted using theoretical methods, and the results may provide experimentalists with guidance for rational design and engineering of novel MOMs. The theory levels used include semi-empirical quantum mechanical calculations with the PM7 Hamiltonian and, Density Functional Theory (DFT) to predict the geometry and electronic structure of the ground state, and Time Dependent DFT (TD-DFT) to predict the excited states and the optical properties.The molecular absorption capacity of aldoxime coordinated Zn(II) based MOMs (previously measured experimentally) is predicted by using PM7 Theory level. The 3D structures were optimized with and without host molecules inside the pores. The absorption capacity of these crystals was predicted to be 8H2 or 3N2 per unit cell. When going beyond this limit, the structural integrity of the bulk material becomes fractured and microcrystals are observed both experimentally and theoretically.The linear absorption properties of Co(II) based complexes are known to change color when the coordination number is altered. In order to understand the mechanism of this color change TD-DFT methods are employed. The chromic behavior of the Co(II) based complexes studied was confirmed to be due to a chain in coordination number that resulted in lower metal to ligand distances. These distances destabilize the occupied metal d orbitals, and as a consequence of this, the metal to ligand transition energy is lowered enough to allow the crystals to absorb light at longer wavelengths.Covalent organic frameworks (COFs) present an extension of MOM principles to the main group elements. The synthesis of ordered COFs is possible by using predesigned structures andcarefully selecting the building blocks and their conditions for assembly. The crystals formed by these systems often possess non-linear optical (NLO) properties. Second Harmonic Generation (SHG) is one of the most used optical processes. Currently, there is a great demand for materials with NLO optical properties to be used for optoelectronic, imaging, sensing, among other applications. DFT calculations can predict the second order hyperpolarizability ?2 and tensor components necessary to estimate NLO. These calculations for the ?2 were done with the use of the Berry's finite field approach. An efficient material with high ?2 was designed and the resulting material was predicted to be nearly fivefold higher than the urea standard.Two-photon absorption (2PA) is another NLO effect. Unlike SHG, it is not limited to acentric material and can be used development of in vivo bio-imaging agents for the brain. Pt(II) complexes with porphyrin derivatives are theoretically studied for that purpose. The mechanism of 2PA enhancement was identified. For the most efficient porphyrin, the large 2PA cross-section was found to be caused by a HOMO-LUMO+2 transition. This transition is strongly coupled to 1PA allowed Q-band HOMO-LUMO states by large transition dipoles. Alkyl carboxyl substituents delocalize the LUMO+2 orbital due to their strong ?-acceptor effect, enhancing transition dipoles and lowering the 2PA transition to the desirable wavelengths range.The mechanism 2PA cross-section enhancement of aminoxime and aldoxime ligands upon metal addition of is studied with TD-DFT methods. This mechanism of enhancement is found to be caused by the polarization of the ligand orbitals by the metal cation. After polarization an increase in ligand to ligand transition dipole moment. This enhancement of dipole moment is related to the increase in 2PA cross-sections.
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Date Issued: 2015
Identifier: CFE0005990, ucf:50777
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005990

Title: Biomechanics of Developmental Dysplasia of the Hip - An engineering study of closed reduction utilizing the Pavlik harness for a range of subtle to severe dislocations in infants.
Creator: Huayamave, Victor, Divo, Eduardo, Kassab, Alain, Reddi, Lakshmi, University of Central Florida
Abstract / Description: Developmental Dysplasia of the Hip (DDH) is an abnormal condition where hip joint dislocation, misalignment, or instability is present in infants. Rates of incidence of DDH in newborn infants have been reported to vary between 1 and 20 per 1000 births, making it the most common congenital malformation of the musculoskeletal system. DDH early detection and treatment is critical to avoid the use of surgical treatment in infants and to prevent future complications such as osteoarthritis in adult...
Show moreDevelopmental Dysplasia of the Hip (DDH) is an abnormal condition where hip joint dislocation, misalignment, or instability is present in infants. Rates of incidence of DDH in newborn infants have been reported to vary between 1 and 20 per 1000 births, making it the most common congenital malformation of the musculoskeletal system. DDH early detection and treatment is critical to avoid the use of surgical treatment in infants and to prevent future complications such as osteoarthritis in adult life. To this day several non-surgical treatments involving the use of harnesses and braces have been proposed to treat DDH in infants, with the Pavlik harness being the current non-surgical standard used to treat DDH at early stages. Although the Pavlik harness has been proven to be successful treating subtle dislocations, severe dislocations do not always reduce. Until now the use of the harness remains an empirical method, and its effectiveness often depends on physician expertise or trial-error procedures; thus a clear guideline has not been established to determine the best optimal harness configuration to treat both subtle and severe dislocations. The goal of this dissertation is to understand the connection between reductions for subtle and severe dislocations and passive muscle forces and moments generated while the harness is used during treatment. While the understanding of DDH biomechanics will provide a valuable clinically applicable approach to optimize and increase harness success rate, it is not without its difficulties. This research has created and developed a three-dimensional based on patient-specific geometry of an infant lower limb. The kinematics and dynamics of the lower limb were defined by modeling the hip, femur, tibia, fibula, ankle, foot, and toe bones. The lines of action of five (5) adductor muscles, namely, the Adductor Brevis, Adductor Longus, Adductor Magnus, Pectineus, and Gracilis were identified as mediators of reduction and its mechanical behavior was characterized using a passive response. Four grades (1-4) of dislocation as specified by the International Hip Dysplasia Institute (IHDI) were considered, and the computer model was computationally manipulated to represent physiological dislocations. To account for proper harness modeling, the femur was restrained to move in an envelope consistent with its constraints. The model of the infant lower limb has been used to analyze subtle and severe dislocations. Results are consistent with previous studies based on a simplified anatomically-consistent synthetic model and clinical reports of very low success of the Pavlik harness for severe dislocations. Furthermore the findings on this work suggest that for severe dislocations, the use of the harness could be optimized to achieve hyperflexion of the lower limb leading to successful reduction for cases where the harness fails.This approach provides three main advantages and innovations: 1) the used of patient-specific geometry to elucidate the biomechanics of DDH; 2) the ability to computationally dislocate the model to represent dislocation severity; and 3) the quantification of external forces needed to accomplish reduction for severe dislocations. This study aims to offer a practical solution to effective treatment that draws from engineering expertise and modeling capabilities and also draws upon medical input. The findings of this work will lay the foundation for future optimization of non-surgical methods critical for the treatment of DDH.
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Date Issued: 2015
Identifier: CFE0005631, ucf:50216
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005631

Title: Prediction of Optical Properties of Pi-Conjugated Organic Materials for Technological Innovations.
Creator: Nayyar, Iffat, Masunov, Artem, Saha, Haripada, Stolbov, Sergey, Gesquiere, Andre, University of Central Florida
Abstract / Description: Organic ?-conjugated solids are promising candidates for new optoelectronic materials. The large body of evidence points at their advantageous properties such as high charge-carrier mobility, large nonlinear polarizability, mechanical flexibility, simple and low cost fabrication and superior luminescence. They can be used as nonlinear optical (NLO) materials with large two-photon absorption (2PA) and as electronic components capable of generating nonlinear neutral (excitonic) and charged ...
Show moreOrganic ?-conjugated solids are promising candidates for new optoelectronic materials. The large body of evidence points at their advantageous properties such as high charge-carrier mobility, large nonlinear polarizability, mechanical flexibility, simple and low cost fabrication and superior luminescence. They can be used as nonlinear optical (NLO) materials with large two-photon absorption (2PA) and as electronic components capable of generating nonlinear neutral (excitonic) and charged (polaronic) excitations. In this work, we investigate the appropriate theoretical methods used for the (a) prediction of 2PA properties for rational design of organic materials with improved NLO properties, and (b) understanding of the essential electronic excitations controlling the energy-transfer and charge-transport properties in organic optoelectronics. Accurate prediction of these electro-optical properties is helpful for structure-activity relationships useful for technological innovations.In Chapter 1 we emphasize on the potential use of the organic materials for these two applications. The 2PA process is advantageous over one-photon absorption for deep-tissue fluorescence microscopy, photodynamic therapy, microfabrication and optical data storage owing to the three-dimensional spatial selectivity and improved penetration depth in the absorbing or scattering media. The design of the NLO materials with large 2PA cross-sections may reduce the optical damage due to the use of the high intensity laser beams for excitation. The organic molecules also possess self-localized excited states which can decay radiatively or nonradiatively to form excitonic states. This suggests the use of these materials in the electroluminescent devices such as light-emitting diodes and photovoltaic cells through the processes of exciton formation or dissociation, respectively. It is therefore necessary to understand ultrafast relaxation processes required in understanding the interplay between the efficient radiative transfer between the excited states and exciton dissociation into polarons for improving the efficiency of these devices. In Chapter 2, we provide the detailed description of the various theoretical methods applied for the prediction as well as the interpretation of the optical properties of a special class of substituted PPV [poly (p-phenylene vinylene)] oligomers. In Chapter 3, we report the accuracy of different second and third order time dependent density functional theory (TD-DFT) formalisms in prediction of the 2PA spectra compared to the experimental measurements for donor-acceptor PPV derivatives. We recommend a posteriori Tamm-Dancoff approximation method for both qualitative and quantitative analysis of 2PA properties. Whereas, Agren's quadratic response methods lack the double excitations and are not suitable for the qualitative analysis of the state-specific contributions distorting the overall quality of the 2PA predictions. We trace the reasons to the artifactual excited states above the ionization threshold. We also study the effect of the basis set, geometrical constraints and the orbital exchange fraction on the 2PA excitation energies and cross-sections. Higher exchange (BMK and M05-2X) and range-separated (CAM-B3LYP) hybrid functionals are found to yield inaccurate predictions both quantitatively and qualitatively. The failure of the exchange-correlation (XC) functionals with correct asymptotic is traced to the inaccurate transition dipoles between the valence states, where functionals with low HF exchange succeed. In Chapter 4, we test the performance of different semiempirical wavefunction theory methods for the prediction of 2PA properties compared to the DFT results for the same set of molecules. The spectroscopic parameterized (ZINDO/S) method is relatively better than the general purpose parameterized (PM6) method but the accuracy is trailing behind the DFT methods. The poor performances of PM6 and ZINDO/S methods are attributed to the incorrect description of excited-to-excited state transition and 2PA energies, respectively. The different semiempirical parameterizations can at best be used for quantitative analysis of the 2PA properties. The ZINDO/S method combined with different orders of multi-reference configuration interactions provide an improved description of 2PA properties. However, the results are observed to be highly dependent on the specific choice for the active space, order of excitation and reference configurations.In Chapter 5, we present a linear response TD-DFT study to benchmark the ability of existing functional models to describe the extent of self-trapped neutral and charged excitations in PPV and its derivative MEH-PPV considered in their trans-isomeric forms. The electronic excitations in question include the lowest singlet (S1) and triplet (T1†) excitons, positive (P+) and negative (P-) polarons and the lowest triplet (T1) states. Use of the long-range-corrected DFT functional, such as LC-wPBE, is found to be crucial in order to predict the physically correct spatial localization of all the electronic excitations in agreement with experiment. The inclusion of polarizable dielectric environment play an important role for the charged states. The particle-hole symmetry is preserved for both the polymers in trans geometries. These studies indicate two distinct origins leading to self-localization of electronic excitations. Firstly, distortion of molecular geometry may create a spatially localized potential energy well where the state wavefunction self-traps. Secondly, even in the absence of geometric and vibrational dynamics, the excitation may become spatially confined due to energy stabilization caused by polarization effects from surrounding dielectric medium.In Chapter 6, we aim to separate these two fundamental sources of spatial localization. We observe the electronic localization of P+ and P- is determined by the polarization effects of the surrounding media and the character of the DFT functional. In contrast, the self-trapping of the electronic wavefunctions of S1 and T1(T1†) mostly follows their lattice distortions. Geometry relaxation plays an important role in the localization of the S1 and T1† excitons owing to the non-variational construction of the excited state wavefunction. While, mean-field calculated P+, P- and T1 states are always spatially localized even in ground state S0 geometry. Polaron P+ and P- formation is signified by the presence of the localized states for the hole or the electron deep inside the HOMO-LUMO gap of the oligomer as a result of the orbital stabilization at the LC-wPBE level. The broadening of the HOMO-LUMO band gap for the T1 exciton compared to the charged states is associated with the inverted bond length alternation observed at this level. The molecular orbital energetics are investigated to identify the relationships between state localization and the corresponding orbital structure.In Chapter 7, we investigate the effect of various conformational defects of trans and cis nature on the energetics and localization of the charged P+ and P- excitations in PPV and MEH-PPV. We observe that the extent of self-trapping for P+ and P- polarons is highly sensitive on molecular and structural conformations, and distribution of atomic charges within the polymers. The particle-hole symmetry is broken with the introduction of trans defects and inclusion of the polarizable environment in consistent with experiment. The differences in the behavior of PPV and MEH-PPV is rationalized based on their orbital energetics and atomic charge distributions. We show these isomeric defects influence the behavior and drift mobilities of the charge carriers in substituted PPVs.
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Date Issued: 2013
Identifier: CFE0005110, ucf:50722
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005110

Title: Study On Anisotropic Plasticity And Fracture Of Lightweight Metal Sheets.
Creator: Jia, Yueqian, Bai, Yuanli, Kassab, Alain, Raghavan, Seetha, Gou, Jihua, Wu, Thomas, University of Central Florida
Abstract / Description: How to reduce weight and increase fuel efficiency is a critical challenge in transportation industries. One way to resolve the problem is to adopting lightweight alloys (i.e. advanced high strength steel, aluminum alloys, or magnesium alloy) in structure designs and manufacturing. Fully understanding the mechanical properties of these materials is a key step.In order to fully characterize the plasticity and fracture of magnesium AZ31B-H24 sheets, a set of mechanical experiments (170 in total)...
Show moreHow to reduce weight and increase fuel efficiency is a critical challenge in transportation industries. One way to resolve the problem is to adopting lightweight alloys (i.e. advanced high strength steel, aluminum alloys, or magnesium alloy) in structure designs and manufacturing. Fully understanding the mechanical properties of these materials is a key step.In order to fully characterize the plasticity and fracture of magnesium AZ31B-H24 sheets, a set of mechanical experiments (170 in total) were performed under both monotonic and non-proportional loading conditions, including monotonic uniaxial tension, notch tension, in-plane uniaxial compression, wide compression (or called biaxial compression), plane strain compression, through-thickness compression, in-plane shear, punch test, uniaxial compression-tension reverse loading, and two-step uniaxial tension (cross-loading).Both the plastic strain histories and stress responses were obtained under the above loading conditions, which give a comprehensive picture of mechanical behaviors of this material. No apparent cross-hardening effect was observed for this material.An extended orthotropic yield criterion involving two linear anisotropic transformation tensors, CPB06ex2, in conjunction with its associated flow rule was fully calibrated to describe both the anisotropy in plastic flow and tension-compression asymmetry in stress-strain behaviors.A fully modularized framework to combine isotropic, kinematic, and cross hardening behaviors was established under non-monotonic loading conditions. Three sets of state variables were defined and applied to consider the effects of, a) loading history, b) twinning and de-twinning and c) different pre-strain.In order to predict ductile fracture of metal sheets, the (")mixed(") stress/strain invariants based Modified-Mohr-Coulomb (MMC) fracture model was transferred into an all-strain based MMC (eMMC) model under plane stress condition, predicting the fracture strain dependent on strain ratio or ? angle, instead of stress triaxiality and Lode angle parameter. The strain ratio or ? angle could be directly measured by digital image correlation (DIC), while the latter required finite element analysis to be determined. This method makes it possible to study material fracture behavior while bypassing plasticity. The eMMC fracture locus can be fully calibrated by fracture strains directly measured from DIC. The fracture strain was also extended by a linear transformation operating to the plastic strain tensor to incorporate the fracture anisotropy. All models were implemented into Abaqus/Explicit as a user material subroutine (VUMAT). Good prediction capability has been demonstrated for magnesium AZ31B-H24 sheets by FE simulation using shell elements.The current framework was also applied for TRIP780, BH240, DP600, and EDDQ steel sheets with adjustment, under different loading conditions. The FE simulation results for TRIP780 correlated well with experimental data under different monotonic loading conditions. The analytical results for BH240, DP600, and EDDQ demonstrated good prediction capability for cross-hardening behavior, and validated by the non-proportional experimental data under two-stage uniaxial tension.
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Date Issued: 2016
Identifier: CFE0006121, ucf:51165
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006121

Title: A Comparative Evaluation of FDSA,GA, and SA Non-Linear Programming Algorithms and Development of System-Optimal Dynamic Congestion Pricing Methodology on I-95 Express.
Creator: Graham, Don, Radwan, Ahmed, Abdel-Aty, Mohamed, Al-Deek, Haitham, Uddin, Nizam, University of Central Florida
Abstract / Description: As urban population across the globe increases, the demand for adequatetransportation grows. Several strategies have been suggested as a solution to the congestion which results from this high demand outpacing the existing supply of transportation facilities.High (-)Occupancy Toll (HOT) lanes have become increasingly more popular as a feature on today's highway system. The I-95 Express HOT lane in Miami Florida, which is currently being expanded from a single Phase (Phase I) into two Phases,...
Show moreAs urban population across the globe increases, the demand for adequatetransportation grows. Several strategies have been suggested as a solution to the congestion which results from this high demand outpacing the existing supply of transportation facilities.High (-)Occupancy Toll (HOT) lanes have become increasingly more popular as a feature on today's highway system. The I-95 Express HOT lane in Miami Florida, which is currently being expanded from a single Phase (Phase I) into two Phases, is one such HOT facility. With the growing abundance of such facilities comes the need for in- depth study of demand patterns and development of an appropriate pricing scheme which reduces congestion.This research develops a method for dynamic pricing on the I-95 HOT facility such as to minimize total travel time and reduce congestion. We apply non-linear programming (NLP) techniques and the finite difference stochastic approximation (FDSA), genetic algorithm (GA) and simulated annealing (SA) stochastic algorithms to formulate and solve the problem within a cell transmission framework. The solution produced is the optimal flow and optimal toll required to minimize total travel time and thus is the system-optimal solution.We perform a comparative evaluation of FDSA, GA and SA non-linear programmingalgorithms used to solve the NLP and the ANOVA results show that there are differences in the performance of the NLP algorithms in solving this problem and reducing travel time. We then conclude by demonstrating that econometric forecasting methods utilizing vector autoregressive (VAR) techniques can be applied to successfully forecast demand for Phase 2 of the 95 Express which is planned for 2014.
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Date Issued: 2013
Identifier: CFE0005000, ucf:50019
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005000

Title: Transient and Distributed Algorithms to Improve Islanding Detection Capability of Inverter Based Distributed Generation.
Creator: Alhosani, Mohamed, Qu, Zhihua, Mikhael, Wasfy, Haralambous, Michael, Behal, Aman, Xu, Chengying, University of Central Florida
Abstract / Description: Recently, a lot of research work has been dedicated toward enhancing performance, reliability and integrity of distributed energy resources that are integrated into distribution networks. The problem of islanding detection and islanding prevention (i.e. anti-islanding) has stimulated a lot of research due to its role in severely compromising the safety of working personnel and resulting in equipment damages. Various Islanding Detection Methods (IDMs) have been developed within the last ten...
Show moreRecently, a lot of research work has been dedicated toward enhancing performance, reliability and integrity of distributed energy resources that are integrated into distribution networks. The problem of islanding detection and islanding prevention (i.e. anti-islanding) has stimulated a lot of research due to its role in severely compromising the safety of working personnel and resulting in equipment damages. Various Islanding Detection Methods (IDMs) have been developed within the last ten years in anticipation of the tremendous increase in the penetration of Distributed Generation (DG) in distribution system. This work proposes new IDMs that rely on transient and distributed behaviors to improve integrity and performance of DGs while maintaining multi-DG islanding detection capability.In this thesis, the following questions have been addressed: How to utilize the transient behavior arising from an islanding condition to improve detectability and robust performance of IDMs in a distributive manner? How to reduce the negative stability impact of the well-known Sandia Frequency Shift (SFS) IDM while maintaining its islanding detection capability? How to incorporate the perturbations provided by each of DGs in such a way that the negative interference of different IDMs is minimized without the need of any type of communication among the different DGs?It is shown that the proposed techniques are local, scalable and robust against different loading conditions and topology changes. Also, the proposed techniques can successfully distinguish an islanding condition from other disturbances that may occur in power system networks. This work improves the efficiency, reliability and safety of integrated DGs, which presents a necessary advance toward making electric power grids a smart grid.
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Date Issued: 2013
Identifier: CFE0005295, ucf:50567
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005295

Finite Element Analysis (2)	+ -
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Two-Photon Absorption (2)	+ -
non-linear muscle model (2)	+ -
ANOVA (1)	+ -

ANSYS (1)	+ -
Algorithms (1)	+ -
All-strain Based Modified-Mohr-Coulomb Fracture Model (1)	+ -
Amplitude Estimation (1)	+ -
Analytical method (1)	+ -
Anisotropic Fracture (1)	+ -
Anisotropic plasticity (1)	+ -
Aquarius (1)	+ -
Aristotle (1)	+ -
Bayesian machine learning (1)	+ -
Boundedly Rational (1)	+ -
Brownian motion (1)	+ -
CONOE Microwave Radiometer (1)	+ -
Cascaded Buck Boost Converter (1)	+ -
Chrage Transport (1)	+ -
Component Non-Linearity (1)	+ -
Computational Chemistry (1)	+ -
Cross Hardening (1)	+ -
DFT (1)	+ -
Demand forecast (1)	+ -
Developmental Dysplasia of the Hip (1)	+ -
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Distributed Generation (1)	+ -

University of Central Florida (15)	+ -
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Mikhael, Wasfy (3)	+ -
Divo, Eduardo (2)	+ -
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Alhosani, Mohamed (1)	+ -
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