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Modeling and Transient Simulation of a Fully Integrated Multi-Pressure Heat Recovery Steam Generator Using Siemens T3000
Title
Modeling and Transient Simulation of a Fully Integrated Multi-Pressure Heat Recovery Steam Generator Using Siemens T3000.
Creator
McConnell, Jonathan, Das, Tuhin, Chow, Louis, Tian, Tian, University of Central Florida
Abstract / Description
The focus of this research is on the transient thermodynamic properties and dynamic behavior of a Heat Recovery Steam Generator (HRSG). An HRSG is a crossflow heat exchanger designed for the extraction of energy from the hot exhaust gas of a traditional power plant through boiling induced phase change. Superheated steam is sent through a turbine to generate additional power, raising the overall efficiency of a power plant. The addition of renewable energies and the evolution of smart grids...
Show moreThe focus of this research is on the transient thermodynamic properties and dynamic behavior of a Heat Recovery Steam Generator (HRSG). An HRSG is a crossflow heat exchanger designed for the extraction of energy from the hot exhaust gas of a traditional power plant through boiling induced phase change. Superheated steam is sent through a turbine to generate additional power, raising the overall efficiency of a power plant. The addition of renewable energies and the evolution of smart grids have brought forth a necessity to gain a comprehensive understanding of transient behavior within an HRSG in order to efficiently manage the power output of traditional plants. Model-based techniques that can simulate a wide range of operating conditions can be valuable and insightful. For this reason, a multi-physics model of an HRSG has been developed in Siemens T3000 plant monitoring software. The layout and conditions of a reference HRSG have been provided by Siemens Energy Inc. along with validation data for behavioral comparison. The HRSG selected is a three pressure stage HRSG. Simultaneous simulation of these three pressure systems and their interactions has been achieved. A potential for real time execution was demonstrated. An HRSG is built of three major subsystems, namely economizers, boilers, and superheaters. A lumped control volume approach has been implemented to efficiently model the energy and mass balances of medium within each subsystem. In this effort, considering the goal of real time simulation, special attention was paid to balance computational burden with numerical accuracy.A major focus of this research has been accurately modeling the complexities of phase change within a boiler subsystem. A switching mechanism has been developed to numerically model the dynamic heating and evaporation of boiler liquid. To increase robustness of the model to numerical fluctuations and perturbations, bidirectional flow comprising of boiling and condensation was modeled with the switching mechanism. This numerically robust model shows good agreement with the validation data provided by Siemens.
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Date Issued
2019
Identifier
CFE0007683, ucf:52459
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007683
SOLAR-BASED SINGLE-STAGE HIGH-EFFICIENCY GRID-CONNECTED INVERTER
Title
SOLAR-BASED SINGLE-STAGE HIGH-EFFICIENCY GRID-CONNECTED INVERTER.
Creator
Tian, Feng, BATARSEH, ISSA, University of Central Florida
Abstract / Description
Renewable energy source plays an important role in the energy cogeneration and distribution. Traditional solar-based inverter system is two stages in cascaded, which has a simpler controller but low efficiency. A new solar-based single-stage grid-connected inverter system can achieve higher efficiency by reducing the power semiconductor switching loss and output stable and synchronized sinusoid current into the utility grid. Controlled by the digital signal processor, the inverter can also...
Show moreRenewable energy source plays an important role in the energy cogeneration and distribution. Traditional solar-based inverter system is two stages in cascaded, which has a simpler controller but low efficiency. A new solar-based single-stage grid-connected inverter system can achieve higher efficiency by reducing the power semiconductor switching loss and output stable and synchronized sinusoid current into the utility grid. Controlled by the digital signal processor, the inverter can also draw maximum power from the solar array, thereby maximizing the utilization of the solar array. In Chapter 1, a comparison between the traditional two-stage inverter and the single-stage inverter is made. To increase the ability of power processing and enhance the efficiency further, a full-bridge topology is chosen, which applies the phase-shift technique to achieve zero-voltage transition. In Chapter 2, average-mode and switch-mode Pspice simulations are applied. All the features of the inverter system are verified, such as stability, zero voltage transition and feed-forward compensation, etc. All these simulation results provide useful design tips for prototyping. In Chapter 3, a phase-shift controller is designed based on UCC3895. Also, a detailed design procedure is given, including key components selection, transformer and inductor design and driver circuits design. In Chapter 4, experimental results of a prototype DC/DC converter are presented and analyzed. By optimization of the circuit, the problems of the prototype are solved and the prototype is working stably. The thesis' conclusion is given in Chapter 5.
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Date Issued
2005
Identifier
CFE0000468, ucf:46414
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000468
LASER METALLIZATION AND DOPING FOR SILICON CARBIDE DIODE FABRICATION AND ENDOTAXY
Title
LASER METALLIZATION AND DOPING FOR SILICON CARBIDE DIODE FABRICATION AND ENDOTAXY.
Creator
Tian, Zhaoxu, Kar, Aravinda, University of Central Florida
Abstract / Description
Silicon carbide is a promising semiconductor material for high voltage, high frequency and high temperature devices due to its wide bandgap, high breakdown electric field strength, highly saturated drift velocity of electrons and outstanding thermal conductivity. With the aim of overcoming some challenges in metallization and doping during the fabrication of silicon carbide devices, a novel laser-based process is provided to direct metallize the surface of silicon carbide without metal...
Show moreSilicon carbide is a promising semiconductor material for high voltage, high frequency and high temperature devices due to its wide bandgap, high breakdown electric field strength, highly saturated drift velocity of electrons and outstanding thermal conductivity. With the aim of overcoming some challenges in metallization and doping during the fabrication of silicon carbide devices, a novel laser-based process is provided to direct metallize the surface of silicon carbide without metal deposition and dope in silicon carbide without high temperature annealing, as an alternative to the conventional ion implantation, and find applications of this laser direct write metallization and doping technique on the fabrication of diodes, endotaxial layer and embedded optical structures on silicon carbide wafers. Mathematical models have been presented for the temperature distributions in the wafer during laser irradiation to optimize laser process parameters and understand the doping and metallization mechanisms in laser irradiation process. Laser irradiation of silicon carbide in a dopant-containing ambient allows to simultaneously heating the silicon carbide surface without melting and incorporating dopant atoms into the silicon carbide lattice. The process that dopant atoms diffuse into the bulk silicon carbide by laser-induced solid phase diffusion (LISPD) can be explained by considering the laser enhanced substitutional and interstitial diffusion mechanisms. Nitrogen and Trimethyaluminum (TMA) are used as dopants to produce n-type and p-type doped silicon carbide, respectively. Two laser doping methods, i.e., internal heating doping and surface heating doping are presented in this dissertation. Deep (800 nm doped junction for internal heating doping) and shallow (200 nm and 450 nm doped junction for surface heating doping) can be fabricated by different doping methods. Two distinct diffusion regions, near-surface and far-surface regions, were identified in the dopant concentration profiles, indicating different diffusion mechanisms in these two regions. The effective diffusion coefficients of nitrogen and aluminum were determined for both regions by fitting the diffusion equation to the measured concentration profiles. The calculated diffusivities are at least 6 orders of magnitude higher than the typical values for nitrogen and aluminum, which indicate that laser doping process enhances the diffusion of dopants in silicon carbide significantly. No amorphization was observed in laser-doped samples eliminating the need for high temperature annealing. Laser direct metallization can be realized on the surface of silicon carbide by generating metal-like conductive phases due to the decomposition of silicon carbide. The ohmic property of the laser direct metallized electrodes can be dramatically improved by fabricating such electrodes on laser heavily doped SiC substrate. This laser-induced solid phase diffusion technique has been utilized to fabricate endolayers in n-type 6H-SiC substrates by carbon incorporation. X-ray energy dispersive spectroscopic analysis shows that the thickness of endolayer is about 100 nm. High resolution transmission electron microscopic images indicate that the laser endotaxy process maintains the crystalline integrity of the substrate without any amorphization. Rutherford backscattering studies also show no amorphization and evident lattice disorder occur during this laser solid phase diffusion process. The resistivity of the endolayer formed in a 1.55 omega•cm silicon carbide wafer segment was found to be 1.1E5 omega•cm which is sufficient for device fabrication and isolation. Annealing at 1000 oC for 10 min to remove hydrogen resulted in a resistivity of 9.4E4 omega•cm. Prototype silicon carbide PIN diodes have been fabricated by doping the endolayer and parent silicon carbide epilayer with aluminum using this laser-induced solid phase diffusion technique to create p-regions on the top surfaces of the substrates. Laser direct metallized contacts were also fabricated on selected PIN diodes to show the effectiveness of these contacts. The results show that the PIN diode fabricated on a 30 nm thick endolayer can block 18 V, and the breakdown voltages and the forward voltages drop at 100 A/cm2 of the diodes fabricated on 4H-SiC with homoepilayer are 420 ~ 500 V and 12.5 ~ 20 V, respectively. The laser direct metallization and doping technique can also be used to synthesize embedded optical structures, which can increase 40% reflectivity compared to the parent wafer, showing potential for the creation of optical, electro-optical, opto-electrical, sensor devices and other integrated structures that are stable in high temperature, high-pressure, corrosive environments and deep space applications.
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Date Issued
2006
Identifier
CFE0001061, ucf:46803
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001061
PULSE FREQUENCY MODULATION ZCS FLYBACK CONVERTER IN INVERTER APPLICATIONS
Title
PULSE FREQUENCY MODULATION ZCS FLYBACK CONVERTER IN INVERTER APPLICATIONS.
Creator
Tian, Feng, Batarseh, Issa, University of Central Florida
Abstract / Description
Renewable energy source plays an important role in energy co-generation and distribution. A traditional solar-based inverter system has two stages cascaded, which has simpler controller but low efficiency. A new solar-based single-stage grid-connected inverter system can achieve higher efficiency by reducing the power semiconductor switching loss and output stable and synchronizing sinusoid current into the utility grid. In Chapter 1, the characteristic I-V and P-V curve of PV array has been...
Show moreRenewable energy source plays an important role in energy co-generation and distribution. A traditional solar-based inverter system has two stages cascaded, which has simpler controller but low efficiency. A new solar-based single-stage grid-connected inverter system can achieve higher efficiency by reducing the power semiconductor switching loss and output stable and synchronizing sinusoid current into the utility grid. In Chapter 1, the characteristic I-V and P-V curve of PV array has been illustrated. Based on prediction of the PV power capacity installed on the grid-connected and off-grid, the trends of grid-tied inverter for DG system have been analyzed. In Chapter 2, the topologies of single-phase grid-connect inverter system have been listed and compared. The key parameters of all these topologies are listed in a table in terms of topology, power decoupling, isolation, bi-directional/uni-directional, power rating, switching frequency, efficiency and input voltage. In Chapter 3, to reduce the capacitance of input filter, an active filter has been proposed, which will eliminate the 120/100Hz low frequency ripple from the PV array's output voltage completely. A feedforward controller is proposed to optimize the step response of PV array output voltage. A sample and hold also is used to provide the 120/100Hz low frequency decoupling between the controller of active filter and inverter stage. In Chapter 4, the single-stage inverter is proposed. Compared with conventional two-stage inverter, which has two high frequency switching stages cascaded, the single-stage inverter system increases the system efficiency by utilizing DC/DC converter to generate rectified sinusoid voltage. A transformer analysis is conducted for the single-stage inverter system, which proves the transformer has no low-frequency magnetic flux bias. To apply peak current mode control on single-stage inverter and get unified loop gain, adaptive slope compensation is also proposed for single-stage inverter. In Chapter 5, a digital controller for single-stage inverter is designed and optimized by the Matlab Control Toolbox. A Psim simulation verified the performance of the digital controller design. In Chapter 6, three bi-directional single-stage inverter topologies are proposed and compared. A conventional single-stage bi-directional inverter has certain shortcoming that cannot be overcome. A modular grid-connect micro-inverter system with dedicated reactive energy processing unit can overcome certain shortcoming and increase the system efficiency and reliability. A unique controller design is also proposed. In Chapter 7, a PFM ZCS flyback inverter system is invented. By using half-wave quasi-resonant ZCS flyback resonant converter and PFM control, this topology completely eliminates switching loss. A detailed mathematical analysis provides all the key parameters for the inverter design. As the inductance of transformer secondary side get smaller, the power stage transfer function of PFM ZCS flyback inverter system demonstrates nonlinearity. An optimized PFM ZCS flyback DC/DC converter design resolves this issue by introducing a MOSFET on the secondary side of transformer. In Chapter 8, experimental results of uni-direcitonal single-stage inverter with grid-connection, bi-directional single-stage inverter and single-stage PFM ZCS flyback inverter have been provided. Conclusions are given in Chapter 9.
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Date Issued
2009
Identifier
CFE0002664, ucf:48198
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002664
Three Studies Examining the Effects of Business Analytics on Judgment and Decision Making in Accounting
Title
Three Studies Examining the Effects of Business Analytics on Judgment and Decision Making in Accounting.
Creator
Lang, Bradley, Trompeter, Gregory, Robb, Sean, Tian, Yu, Trinkle, Brad, University of Central Florida
Abstract / Description
This dissertation consists of three studies investigating the relationship between business analytics and decision making in accounting. In an effort to improve performance, organizations increasingly emphasize fact-based decision making supported by business analytics, which translate complex data into manageable information through statistical analysis. While the recent focus on business analytics is transforming how managers make decisions, analytics alone do not generate increased...
Show moreThis dissertation consists of three studies investigating the relationship between business analytics and decision making in accounting. In an effort to improve performance, organizations increasingly emphasize fact-based decision making supported by business analytics, which translate complex data into manageable information through statistical analysis. While the recent focus on business analytics is transforming how managers make decisions, analytics alone do not generate increased performance; the synergy between business analytics and user judgments is a vital component of realizing value. To this end, Study I experimentally investigates how various characteristics of business analytics affect individuals' reliance and perceptions of the analytic. Through the lens of cognitive fit a 2(&)#215;2 between-subjects experiment is conducted examining business analytics effects of input and process attributes on users' reliance. Cognitive fit theory posits that effective problem solving depends on the match between the technology and the decision process. The second study investigates the impact of management interventions (i.e. actions influencing adoption) toward improving reliance on business analytics. From an organizational perspective, an important concern for management is promoting greater employee acceptance and utilization of business analytics. Building on the Technology Acceptance Model, Study II experimentally examines the effect of management support and consensus of multiple analytics on increasing reliance and on participants' evaluation of the business analytic. Study III further explores the relationship between characteristics of business analytics and the decision maker by developing a theoretical model regarding the effects of perceived decision similarities between the user and the business analytic on users' perceived usefulness. Overall, the results reported in this dissertation suggest that 1) characteristics of business analytics influence users' judgments and decision making, 2) management can take actions to influence the relationship between users and business analytics, and 3) users are likely to evaluate their cognitive similarity to these business analytics, and these perceptions influence perceived usefulness of the business analytics.
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Date Issued
2018
Identifier
CFE0007578, ucf:52562
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007578
Three Studies Examining The Effects of Informal Management Control Systems and Incentive Compensation Schemes on Employees' Performance
Title
Three Studies Examining The Effects of Informal Management Control Systems and Incentive Compensation Schemes on Employees' Performance.
Creator
Akinyele, Kazeem, Arnold, Vicky, Sutton, Steven, Tian, Yu, Libby, Theresa, University of Central Florida
Abstract / Description
This dissertation is comprised of three studies investigating the effects of informal management control systems (MCS) and different types of incentive compensation schemes on employees' performance. Prior research describes informal MCS as implicit sets of structures that management adopts to encourage employees to act in a way that aligns with overall organizational goals (Berry et al. 2009). Management usually puts informal MCS in place to inspire self-regulation behaviors among employees;...
Show moreThis dissertation is comprised of three studies investigating the effects of informal management control systems (MCS) and different types of incentive compensation schemes on employees' performance. Prior research describes informal MCS as implicit sets of structures that management adopts to encourage employees to act in a way that aligns with overall organizational goals (Berry et al. 2009). Management usually puts informal MCS in place to inspire self-regulation behaviors among employees; hence, management may not reward or penalize employee behavior that is consistent or inconsistent with this informal MCS (Berry et al. 2009; Christ et al. 2008). Informal controls are implied by social pressures, such as employees' feedback, and management communication, such as a value statement or the organizational culture, where no explicit enforcement measures exist (Berry et al. 2009; Kachelmeier, Thornock and Williamson 2015). The first study examines whether the presence of a value statement (an informal MCS) can be used to motivate employees to perform important, but uncompensated subsequent tasks. The second study extends the first study by examining whether the interactive method of delivery of a value statement (informal MCS) can be used in conjunction with an incentive scheme to improve employees' performance. Lastly, the third study investigates the impact of an important aspect of organizational context, specifically organizational culture (informal MCS), and different types of incentive compensation schemes on strategy surrogation. The first study investigates whether the presence of a value statement (an informal MCS) can be used to motivate employees to perform important, but uncompensated tasks. Additionally, this study seeks to examine the type of incentive scheme that will result in the highest subsequent uncompensated task performance in the presence of an organizational value statement. Considering that incentive contracts cannot completely govern all the employees' responsibilities (Christ, Emett, Summers and Wood 2012), this study investigates how employees will perform their important but uncompensated tasks. The study shows that under fixed pay compensation, the presence of a value statement improves the performance of employees compared to the absence of a value statement. Conversely, under a piece rate incentive compensation, the presence of a value statement negatively influences the performance of employees in the important but uncompensated task. The study also shows that the intrinsic motivation of employees operating under piece rate compensation is more likely to be crowded out by their incentive pay relative to employees operating under a fixed wage. The second study examines whether the interactive method of delivery of a value statement (informal MCS) through electronic integration can be used in conjunction with an incentive scheme to improve employees' performance. Prior research shows that effectiveness of incentive systems is influenced by the presence or absence of a nonbinding value statement in the organization. A value statement is a declaration that communicates an organization's priorities and core beliefs to its customers and employees. Drawing upon the mere-exposure effect, the results of the study show that the employees who experience the interactive delivery of a value statement do not perform significantly better than employees who experience the passive delivery of a value statement. However, employees who receive a piece-rate incentive perform significantly better than employees who receive a fixed pay incentive. As predicted, the method of delivery of an organizational value statement moderates the effectiveness of a fixed pay incentive scheme.The third study draws upon the theory of inattentional blindness to investigate whether different types of organizational culture, control dominant or flexibility dominant, impacts strategy surrogation. Strategy surrogation occurs when managers focus on the measures in the SPMS on which they are compensated and completely or partially lose focus on the overall strategic objectives of the organization (Choi et al. 2012, 2013). Organizational culture is defined as a set of dominant values, beliefs, and assumptions that governs how people behave in organizations (Henri 2006). The results of the study show that there is no significant difference between employees operating under a control-dominant culture and employees operating under a flexibility-dominant culture. Similarly, the type of organizational culture does not moderate the relationship between incentive systems and strategy surrogation. However, employees operating under a pay-for-performance compensation scheme significantly surrogate more than employees operating under a fixed pay compensation scheme.Collectively these studies contribute to management accounting research by examining how different types of informal MCS such as organizational value statement and organizational culture interact with incentive compensation scheme. Specifically, these three studies highlight how and when we can use informal MCS to improve employees' performance as well as their decision making in the organization. Study one contributes to research and practice by highlighting situations where a pay-for-performance incentive scheme may result in unintended consequences. Study two contributes to the management control literature by demonstrating how utilizing technology can enhance the delivery of an organization's value statement and ultimately improve employees' performance. Study three contributes to the incentives and organizational culture literature as well as strategy surrogation research by examining institutional factors that may inhibit or exacerbate surrogation.
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Date Issued
2017
Identifier
CFE0006850, ucf:51783
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006850
System justification theory: Synthesizing and applying its theoretical motivations in behavioral accounting research
Title
System justification theory: Synthesizing and applying its theoretical motivations in behavioral accounting research.
Creator
Olczak, Wioleta, Roberts, Robin, Libby, Theresa, Tian, Yu, Patten, Dennis, University of Central Florida
Abstract / Description
This dissertation consists of two studies on System Justification Theory, hereafter SJT. SJT (Jost and Banaji 1994) is a psychology theory stating that individuals justify the status quo even if doing so is against their own or their group's interest (Jost et al. 2004). Comprised of twenty propositions, SJT attempts to explain social and psychological factors driving individuals to perceive the social system as legitimate. These factors also drive individuals to support and maintain the...
Show moreThis dissertation consists of two studies on System Justification Theory, hereafter SJT. SJT (Jost and Banaji 1994) is a psychology theory stating that individuals justify the status quo even if doing so is against their own or their group's interest (Jost et al. 2004). Comprised of twenty propositions, SJT attempts to explain social and psychological factors driving individuals to perceive the social system as legitimate. These factors also drive individuals to support and maintain the social system. The synthesis and application of this psychological theory in behavioral accounting research is limited, but could provide explanatory evidence on individual decision-making in accounting. The first study of this dissertation synthesizes SJT's four foundational theories (-) cognitive dissonance, social identity, social dominance, and belief in a just world (-) in behavioral accounting research, specifically focusing on two predominantly used theoretical motivations, cognitive dissonance and social identity theory. Behavioral accounting and corporate social responsibility (CSR) have increasingly become more complex as interest in these two areas continues to grow. The first study reviews prior behavioral accounting research that applied cognitive dissonance or social identity theory, and then demonstrates how the application of SJT in behavioral accounting research addresses more complex research questions that cannot be addressed solely from one or a combination of SJT's four foundational theories. The second study then applies SJT's theoretical motivations in a complex managerial accounting setting by investigating whether maintaining the status quo is a factor explaining managers' decisions to overstate environmental capital expenditure (ECE) projections. This study uses an experimental design to understand whether the presence of an overstatement status quo and a system threat affects managers' decisions to overstate environmental projections. The results indicate that managers are more likely to overstate ECE projections when the industry exhibits an overstatement status quo. Additionally, this propensity to overstate ECE projections is further exacerbated when managers face a stakeholder threat, suggesting they (")dig in their heels(") and maintain the status quo. This study extends environmental accounting research by demonstrating that the societal status quo affects managers cognitively and psychologically as they make environmental disclosure decisions. Results also contribute to practice by shedding insight as to why managers make certain environmental disclosure decisions. Specifically, the results show that the social system impacts managers' willingness to use environmental disclosures as a legitimating tool. Overall these two studies contribute to behavioral accounting research by exploring and applying a psychological theory in a managerial environmental accounting setting. It demonstrates how a commonly used psychology theory that has never been utilized in accounting research could address broad and complex accounting topics
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Date Issued
2019
Identifier
CFE0007697, ucf:52447
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007697
Decision Making in Corporate Taxation
Title
Decision Making in Corporate Taxation.
Creator
Brown, Bonnie, Arnold, Vicky, Schmitt, Donna, Kelliher, Charles, Tian, Yu, Rupert, Timothy, University of Central Florida
Abstract / Description
This dissertation is comprised of three experimental studies that examine corporate tax aggressiveness through an investigation of judgment and decision making in the corporate tax environment. Studies 1 and 2 examine individual judgment involved in decision making (i.e., assessments of tax positions based upon tax scenario facts and tax authority). Study 1 examines how advice from external tax advisors and a tax advisor's association with the company's audit firm influences the...
Show moreThis dissertation is comprised of three experimental studies that examine corporate tax aggressiveness through an investigation of judgment and decision making in the corporate tax environment. Studies 1 and 2 examine individual judgment involved in decision making (i.e., assessments of tax positions based upon tax scenario facts and tax authority). Study 1 examines how advice from external tax advisors and a tax advisor's association with the company's audit firm influences the aggressiveness of experienced in-house corporate tax decision makers. Study 2 examines how situational factors in the corporate tax environment interact with individual traits to affect individual-level tax aggressiveness, focusing in greater depth upon the process of individual judgment and decision making. Study 3 extends the investigation of situational factors from individual-level decision making to a group-level analysis, examining individual-level and group-level decision making in a tax setting (i.e., tax compliance decisions).Overall, results reflect the complexity of the corporate tax environment. The effects of the situational factors examined in the dissertation generally influence decision makers' own perceptions. For example, Study 1 results suggest that tax advisor identity influences how corporate tax directors weight advice only if the advice is conservative and if the tax directors agree with the advice. Additionally, in Studies 2 and 3, decision maker perceptions are found to mediate the effects of manipulated situational factors. In Study 2, regulatory focus state indirectly influences individual tax aggressiveness through the perception of the tax advisor's level of client advocacy. In Study 3 decision maker type, a situational factor, affects tax compliance decision riskiness indirectly through feelings of responsibility for the possible outcomes of the decision. Collectively these studies contribute to the nascent literature on decision making in a corporate tax environment, helping to lay the groundwork for future studies in this area.
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Date Issued
2016
Identifier
CFE0006269, ucf:51035
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006269
Human Action Detection, Tracking and Segmentation in Videos
Title
Human Action Detection, Tracking and Segmentation in Videos.
Creator
Tian, Yicong, Shah, Mubarak, Bagci, Ulas, Liu, Fei, Walker, John, University of Central Florida
Abstract / Description
This dissertation addresses the problem of human action detection, human tracking and segmentation in videos. They are fundamental tasks in computer vision and are extremely challenging to solve in realistic videos. We first propose a novel approach for action detection by exploring the generalization of deformable part models from 2D images to 3D spatiotemporal volumes. By focusing on the most distinctive parts of each action, our models adapt to intra-class variation and show robustness to...
Show moreThis dissertation addresses the problem of human action detection, human tracking and segmentation in videos. They are fundamental tasks in computer vision and are extremely challenging to solve in realistic videos. We first propose a novel approach for action detection by exploring the generalization of deformable part models from 2D images to 3D spatiotemporal volumes. By focusing on the most distinctive parts of each action, our models adapt to intra-class variation and show robustness to clutter. This approach deals with detecting action performed by a single person. When there are multiple humans in the scene, humans need to be segmented and tracked from frame to frame before action recognition can be performed. Next, we propose a novel approach for multiple object tracking (MOT) by formulating detection and data association in one framework. Our method allows us to overcome the confinements of data association based MOT approaches, where the performance is dependent on the object detection results provided at input level. We show that automatically detecting and tracking targets in a single framework can help resolve the ambiguities due to frequent occlusion and heavy articulation of targets. In this tracker, targets are represented by bounding boxes, which is a coarse representation. However, pixel-wise object segmentation provides fine level information, which is desirable for later tasks. Finally, we propose a tracker that simultaneously solves three main problems: detection, data association and segmentation. This is especially important because the output of each of those three problems are highly correlated and the solution of one can greatly help improve the others. The proposed approach achieves more accurate segmentation results and also helps better resolve typical difficulties in multiple target tracking, such as occlusion, ID-switch and track drifting.
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Date Issued
2018
Identifier
CFE0007378, ucf:52069
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007378
Optimization problem in single period markets
Title
Optimization problem in single period markets.
Creator
Jiang, Tian, Yong, Jiongmin, Qi, Yuanwei, Shuai, Zhisheng, University of Central Florida
Abstract / Description
There had been a number of researches that investigated on the security market without transactioncosts. The focus of this research is in the area that when the security market with transaction costsis fair and in such fair market how one chooses a suitable portfolio to optimize the financial goal.The research approach adopted in this thesis includes linear algebra and elementary probability.The thesis provides evidence that we can maximize expected utility function to achieve our goal...
Show moreThere had been a number of researches that investigated on the security market without transactioncosts. The focus of this research is in the area that when the security market with transaction costsis fair and in such fair market how one chooses a suitable portfolio to optimize the financial goal.The research approach adopted in this thesis includes linear algebra and elementary probability.The thesis provides evidence that we can maximize expected utility function to achieve our goal(maximize expected return under certain risk tolerance). The main conclusions drawn from thisstudy are under certain conditions the security market is arbitrage-free, and we can always find anoptimal portfolio maximizing certain expected utility function.
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Date Issued
2013
Identifier
CFE0004696, ucf:49875
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004696