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Title: DECISION-MAKER TRADE-OFFS IN MULTIPLE RESPONSE SURFACE OPTIMIZATION.
Creator: Hawkins, Alicia, Armacost, Robert, University of Central Florida
Abstract / Description: The focus of this dissertation is on improving decision-maker trade-offs and the development of a new constrained methodology for multiple response surface optimization. There are three key components of the research: development of the necessary conditions and assumptions associated with constrained multiple response surface optimization methodologies; development of a new constrained multiple response surface methodology; and demonstration of the new method. The necessary conditions for and...
Show moreThe focus of this dissertation is on improving decision-maker trade-offs and the development of a new constrained methodology for multiple response surface optimization. There are three key components of the research: development of the necessary conditions and assumptions associated with constrained multiple response surface optimization methodologies; development of a new constrained multiple response surface methodology; and demonstration of the new method. The necessary conditions for and assumptions associated with constrained multiple response surface optimization methods were identified and found to be less restrictive than requirements previously described in the literature. The conditions and assumptions required for a constrained method to find the most preferred non-dominated solution are to generate non-dominated solutions and to generate solutions consistent with decision-maker preferences among the response objectives. Additionally, if a Lagrangian constrained method is used, the preservation of convexity is required in order to be able to generate all non-dominated solutions. The conditions required for constrained methods are significantly fewer than those required for combined methods. Most of the existing constrained methodologies do not incorporate any provision for a decision-maker to explicitly determine the relative importance of the multiple objectives. Research into the larger area of multi-criteria decision-making identified the interactive surrogate worth trade-off algorithm as a potential methodology that would provide that capability in multiple response surface optimization problems. The ISWT algorithm uses an ε-constraint formulation to guarantee a non-dominated solution, and then interacts with the decision-maker after each iteration to determine the preference of the decision-maker in trading-off the value of the primary response for an increase in value of a secondary response. The current research modified the ISWT algorithm to develop a new constrained multiple response surface methodology that explicitly accounts for decision-maker preferences. The new Modified ISWT (MISWT) method maintains the essence of the original method while taking advantage of the specific properties of multiple response surface problems to simplify the application of the method. The MISWT is an accessible computer-based implementation of the ISWT. Five test problems from the multiple response surface optimization literature were used to demonstrate the new methodology. It was shown that this methodology can handle a variety of types and numbers of responses and independent variables. Furthermore, it was demonstrated that the methodology can be successful using a priori information from the decision-maker about bounds or targets or can use the extreme values obtained from the region of operability. In all cases, the methodology explicitly considered decision-maker preferences and provided non-dominated solutions. The contribution of this method is the removal of implicit assumptions and includes the decision-maker in explicit trade-offs among multiple objectives or responses.
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Date Issued: 2007
Identifier: CFE0001765, ucf:47272
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001765

Title: COMPARING ASSESSMENT METHODS AS PREDICTORS OF STUDENT LEARNING IN UNDERGRADUATE MATHEMATICS.
Creator: Shorter, Nichole, Young, Cynthia, University of Central Florida
Abstract / Description: This experiment was designed to determine which assessment method: continuous assessment (in the form of daily in-class quizzes), cumulative assessment (in the form of online homework), or project-based learning, best predicts student learning (dependent upon posttest grades) in an undergraduate mathematics course. Participants included 117 university-level undergraduate freshmen enrolled in a course titled "Mathematics for Calculus". Initially, a multiple regression model was formulated to...
Show moreThis experiment was designed to determine which assessment method: continuous assessment (in the form of daily in-class quizzes), cumulative assessment (in the form of online homework), or project-based learning, best predicts student learning (dependent upon posttest grades) in an undergraduate mathematics course. Participants included 117 university-level undergraduate freshmen enrolled in a course titled "Mathematics for Calculus". Initially, a multiple regression model was formulated to model the relationship between the predictor variables (the continuous assessment, cumulative assessment, and project scores) versus the outcome variable (the posttest scores). However, due to the possibility of multicollinearity present between the cumulative assessment predictor variable and the continuous assessment predictor variable, a stepwise regression model was implemented and caused the cumulative assessment predictor variable to be forced out of the resulting model, based on the results of statistical significance and hypothesis testing. The finalized stepwise regression model included continuous assessment scores and project scores as predictor variables of students' posttest scores with a 99% confidence level. Results indicated that ultimately the continuous assessment scores best predicted students' posttest scores.
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Date Issued: 2008
Identifier: CFE0002432, ucf:47704
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002432

Title: Dynamic Behavior and Performance of Different Types of Multi-Effect Desalination Plants.
Creator: Abdelkareem, Mohamed, Chow, Louis, Mansy, Hansen, Das, Tuhin, Duranceau, Steven, University of Central Florida
Abstract / Description: Water and energy are two of the most vital resources for the socio-economic development and sustenance of humanity on earth. Desalination of seawater has been practiced for some decades and is a well-established means of water supply. However, this process consumes large amounts of energy and the global energy supply is also faced with some challenges. In this research, multi-effect desalination (MED) has been selected due to lower cost, lower operating temperature and efficient in terms of...
Show moreWater and energy are two of the most vital resources for the socio-economic development and sustenance of humanity on earth. Desalination of seawater has been practiced for some decades and is a well-established means of water supply. However, this process consumes large amounts of energy and the global energy supply is also faced with some challenges. In this research, multi-effect desalination (MED) has been selected due to lower cost, lower operating temperature and efficient in terms of primary energy and electricity consumption compared to other thermal desalination systems. The motivation for this research is to address thermo-economics and dynamic behavior of different MED feed configurations with/without vapor compression (VC). A new formulation for the steady-state models was developed to simulate different MED systems. Adding a thermal vapor compressor (TVC) or mechanical vapor compression (MVC) unit to the MED system is also studied to show the advantage of this type of integration. For MED-TVC systems, results indicate that the parallel cross feed (PCF) configuration has better performance characteristics than other configurations. A similar study of MED-MVC systems indicates that the PCF and forward feed (FF) configurations require less work to achieve equal distillate production. Reducing the steam temperature supplied by the MVC unit leads to an increase in second law efficiency and a decrease in specific power consumption (SPC) and total water price. Following the fact that the MED may be exposed to fluctuations (disturbances) in input parameters during operation. Therefore, there is a requirement to analyze their transient behavior. In the current study, the dynamic model is developed based on solving the basic conservation equations of mass, energy, and salt. In the case of heat source disturbance, MED plants operating in the backward feed (BF) may be exposed to shut down due to flooding in the first effect. For all applied disturbances, the change in the brine level is the slowest compared to the changes in vapor temperature, and brine and vapor flow rates. For MED-TVC, it is recommended to limit the seawater cooling flow rate reduction to under 12% of the steady-state value to avoid dryout in the evaporators. A reduction in the motive steam flow rate and cooling seawater temperature of more than 20% and 35% of steady-state values, respectively, may lead to flooding in evaporators and plant shutdown. Simultaneous combinations of two different disturbances with opposing effects have only a modest effect on plant operation and they can be used to control and mitigate the flooding/drying effects caused by the disturbances. For the MED-MVC, the compressor work reduction could lead to plant shutdown, while a reduction in the seawater temperature will lead to a reduction in plant production and an increase in SPC.
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Date Issued: 2019
Identifier: CFE0007423, ucf:52735
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007423

Title: Exploration and development of crash modification factors and functions for single and multiple treatments.
Creator: Park, Juneyoung, Abdel-Aty, Mohamed, Radwan, Essam, Eluru, Naveen, Wang, Chung-Ching, Lee, JaeYoung, University of Central Florida
Abstract / Description: Traffic safety is a major concern for the public, and it is an important component of the roadway management strategy. In order to improve highway safety, extensive efforts have been made by researchers, transportation engineers, Federal, State, and local government officials. With these consistent efforts, both fatality and injury rates from road traffic crashes in the United States have been steadily declining over the last six years (2006~2011). However, according to the National Highway...
Show moreTraffic safety is a major concern for the public, and it is an important component of the roadway management strategy. In order to improve highway safety, extensive efforts have been made by researchers, transportation engineers, Federal, State, and local government officials. With these consistent efforts, both fatality and injury rates from road traffic crashes in the United States have been steadily declining over the last six years (2006~2011). However, according to the National Highway Traffic Safety Administration (NHTSA, 2013), 33,561 people died in motor vehicle traffic crashes in the United States in 2012, compared to 32,479 in 2011, and it is the first increase in fatalities since 2005. Moreover, in 2012, an estimated 2.36 million people were injured in motor vehicle traffic crashes, compared to 2.22 million in 2011. Due to the demand of highway safety improvements through systematic analysis of specific roadway cross-section elements and treatments, the Highway Safety Manual (HSM) (AASHTO, 2010) was developed by the Transportation Research Board (TRB) to introduce a science-based technical approach for safety analysis. One of the main parts in the HSM, Part D, contains crash modification factors (CMFs) for various treatments on roadway segments and at intersections. A CMF is a factor that can estimate potential changes in crash frequency as a result of implementing a specific treatment (or countermeasure). CMFs in Part D have been developed using high-quality observational before-after studies that account for the regression to the mean threat. Observational before-after studies are the most common methods for evaluating safety effectiveness and calculating CMFs of specific roadway treatments. Moreover, cross-sectional method has commonly been used to derive CMFs since it is easier to collect the data compared to before-after methods.Although various CMFs have been calculated and introduced in the HSM, still there are critical limitations that are required to be investigated. First, the HSM provides various CMFs for single treatments, but not CMFs for multiple treatments to roadway segments. The HSM suggests that CMFs are multiplied to estimate the combined safety effects of single treatments. However, the HSM cautions that the multiplication of the CMFs may over- or under-estimate combined effects of multiple treatments. In this dissertation, several methodologies are proposed to estimate more reliable combined safety effects in both observational before-after studies and the cross-sectional method. Averaging two best combining methods is suggested to use to account for the effects of over- or under- estimation. Moreover, it is recommended to develop adjustment factor and function (i.e. weighting factor and function) to apply to estimate more accurate safety performance in assessing safety effects of multiple treatments. The multivariate adaptive regression splines (MARS) modeling is proposed to avoid the over-estimation problem through consideration of interaction impacts between variables in this dissertation. Second, the variation of CMFs with different roadway characteristics among treated sites over time is ignored because the CMF is a fixed value that represents the overall safety effect of the treatment for all treated sites for specific time periods. Recently, few studies developed crash modification functions (CMFunctions) to overcome this limitation. However, although previous studies assessed the effect of a specific single variable such as AADT on the CMFs, there is a lack of prior studies on the variation in the safety effects of treated sites with different multiple roadway characteristics over time. In this study, adopting various multivariate linear and nonlinear modeling techniques is suggested to develop CMFunctions. Multiple linear regression modeling can be utilized to consider different multiple roadway characteristics. To reflect nonlinearity of predictors, a regression model with nonlinearizing link function needs to be developed. The Bayesian approach can also be adopted due to its strength to avoid the problem of over fitting that occurs when the number of observations is limited and the number of variables is large. Moreover, two data mining techniques (i.e. gradient boosting and MARS) are suggested to use 1) to achieve better performance of CMFunctions with consideration of variable importance, and 2) to reflect both nonlinear trend of predictors and interaction impacts between variables at the same time. Third, the nonlinearity of variables in the cross-sectional method is not discussed in the HSM. Generally, the cross-sectional method is also known as safety performance functions (SPFs) and generalized linear model (GLM) is applied to estimate SPFs. However, the estimated CMFs from GLM cannot account for the nonlinear effect of the treatment since the coefficients in the GLM are assumed to be fixed. In this dissertation, applications of using generalized nonlinear model (GNM) and MARS in the cross-sectional method are proposed. In GNMs, the nonlinear effects of independent variables to crash analysis can be captured by the development of nonlinearizing link function. Moreover, the MARS accommodate nonlinearity of independent variables and interaction effects for complex data structures. In this dissertation, the CMFs and CMFunctions are estimated for various single and combination of treatments for different roadway types (e.g. rural two-lane, rural multi-lane roadways, urban arterials, freeways, etc.) as below:1) Treatments for mainline of roadway: - adding a thru lane, conversion of 4-lane undivided roadways to 3-lane with two-way left turn lane (TWLTL)2) Treatments for roadway shoulder: - installing shoulder rumble strips, widening shoulder width, adding bike lanes, changing bike lane width, installing roadside barriers3) Treatments related to roadside features: - decrease density of driveways, decrease density of roadside poles, increase distance to roadside poles, increase distance to trees Expected contributions of this study are to 1) suggest approaches to estimate more reliable safety effects of multiple treatments, 2) propose methodologies to develop CMFunctions to assess the variation of CMFs with different characteristics among treated sites, and 3) recommend applications of using GNM and MARS to simultaneously consider the interaction impact of more than one variables and nonlinearity of predictors.Finally, potential relevant applications beyond the scope of this research but worth investigation in the future are discussed in this dissertation.
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Date Issued: 2015
Identifier: CFE0005861, ucf:50914
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005861

Title: A Study of Internet Spending and Graduation Rates: A Correlational Study.
Creator: Violette, Diana, Murray, Kenneth, Baldwin, Lee, Doherty, Walter, Jaffe, Larry, University of Central Florida
Abstract / Description: The purpose of this study was to examine the relationship between school district spending on Internet access and student achievement, defined by graduation rates, in the state of Florida. Internet funding received for Internet access from E-rate funding administered by the Universal Service Administration Company (USAC) and graduation rates of the 67 school districts in the state of Florida were compared. Further, the data were adjusted for socio-economic status (SES) to determine the...
Show moreThe purpose of this study was to examine the relationship between school district spending on Internet access and student achievement, defined by graduation rates, in the state of Florida. Internet funding received for Internet access from E-rate funding administered by the Universal Service Administration Company (USAC) and graduation rates of the 67 school districts in the state of Florida were compared. Further, the data were adjusted for socio-economic status (SES) to determine the relationship between school districts' SES and spending on Internet access. Lastly, school district connectivity and bandwidth were examined to determine whether the ConnectED initiative requirements were related to student achievement and the implementation of school district digital learning programs. E-rate funding and graduation rates were not correlated. Regression and multiple regression analyses demonstrated that Internet spending, bandwidth, and ratio of computers to students did not statistically predict graduation rates during the years of the study.
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Date Issued: 2017
Identifier: CFE0006816, ucf:51771
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006816

Title: computational study of traveling wave solutions and global stability of predator-prey models.
Creator: Zhu, Yi, Qi, Yuanwei, Rollins, David, Shuai, Zhisheng, Zhai, Lei, University of Central Florida
Abstract / Description: In this thesis, we study two types of reaction-diffusion systems which have direct applications in understanding wide range of phenomena in chemical reaction, biological pattern formation and theoretical ecology.The first part of this thesis is on propagating traveling waves in a class of reaction-diffusion systems which model isothermal autocatalytic chemical reactions as well as microbial growth and competition in a flow reactor. In the context of isothermal autocatalytic systems, two...
Show moreIn this thesis, we study two types of reaction-diffusion systems which have direct applications in understanding wide range of phenomena in chemical reaction, biological pattern formation and theoretical ecology.The first part of this thesis is on propagating traveling waves in a class of reaction-diffusion systems which model isothermal autocatalytic chemical reactions as well as microbial growth and competition in a flow reactor. In the context of isothermal autocatalytic systems, two different cases will bestudied. The first is autocatalytic chemical reaction of order $m$ without decay. The second is chemical reaction of order $m$ with a decay of order $l$, where $m$ and $l$ are positive integers and $m(>)l\ge1$. A typical system is $A + 2B \rightarrow3B$ and $B\rightarrow C$ involving three chemical species, a reactant A and an auto-catalyst B and C an inert chemical species.We use numerical computation to give more accurate estimates on minimum speed of traveling waves for autocatalytic reaction without decay, providing useful insight in the study of stability of traveling waves. For autocatalytic reaction of order $m = 2$ with linear decay $l = 1$, which hasa particular important role in biological pattern formation, it is shown numerically that there exist multiple traveling waves with 1, 2 and 3 peaks with certain choices of parameters.The second part of this thesis is on the global stability of diffusive predator-prey system of Leslie Type and Holling-Tanner Type in a bounded domain $\Omega\subset R^N$ with no-flux boundary condition. By using a new approach, we establish much improved global asymptotic stability of a unique positiveequilibrium solution. We also show the result can be extended to more general type of systems with heterogeneous environment and/or other kind of kinetic terms.
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Date Issued: 2016
Identifier: CFE0006519, ucf:51359
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006519

Title: On Obama Administration Gun Policy With Continual Reference To The Multiple Streams Model.
Creator: Hristakopoulos, Michael, Vieux, Andrea, Wilson, Bruce, Kinsey, Barbara, University of Central Florida
Abstract / Description: The Multiple Streams model developed by John Kingdon (1995) and Nikolaos Zahariadis (2007) provides a valuable framework for understanding the nature of policy change. This investigation draws extensively upon the Multiple Streams framework in order to understand the development of gun-control policy initiatives under President Barack Obama.The investigation uses a case-study approach with in-depth analysis of four different mass-shooting events that took place in the United States between...
Show moreThe Multiple Streams model developed by John Kingdon (1995) and Nikolaos Zahariadis (2007) provides a valuable framework for understanding the nature of policy change. This investigation draws extensively upon the Multiple Streams framework in order to understand the development of gun-control policy initiatives under President Barack Obama.The investigation uses a case-study approach with in-depth analysis of four different mass-shooting events that took place in the United States between 2009 and 2012. Reconstruction of the shooting events and detailed parsing of the Obama administration's official responses to each incident, when viewed through the Multiple Streams lens, clearly explain why Obama's aggressive policy initiative was so delayed in its emergence in spite of several shootings and the President's clearly stated belief that gun-reform was a necessary step for the federal government. While the term (")policy change(") is broad and may encompass all sorts of governmental responsiveness, the term herein should be interpreted in the narrowest sense: exclusively encompassing legislative initiatives.Ultimately, the investigation concludes that numerous factors, but most prominently concerns about the timing and results of the 2010 Midterm and 2012 General Elections, prevented an aggressive pursuit of gun-reform prior to January 2013. The tragic shooting of 28 people in Newtown, Connecticut, then served as a prime focusing event for the President to aggressively engage a long-standing goal.
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Date Issued: 2013
Identifier: CFE0004865, ucf:49716
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004865

Title: Automated Hybrid Singularity Superposition and Anchored Grid Pattern BEM Algorithm for the Solution of the Inverse Geometric Problem.
Creator: Ni, Marcus, Kassab, Alain, Divo, Eduardo, Chopra, Manoj, University of Central Florida
Abstract / Description: A method for solving the inverse geometrical problem is presented by reconstructing the unknown subsurface cavity geometry using boundary element methods, a genetic algorithm, and Nelder-Mead non-linear simplex optimization. The heat conduction problem is solved utilizing the boundary element method, which calculates the difference between the measured temperature at the exposed surface and the computed temperature under the current update of the unknown subsurface flaws and cavities. In a...
Show moreA method for solving the inverse geometrical problem is presented by reconstructing the unknown subsurface cavity geometry using boundary element methods, a genetic algorithm, and Nelder-Mead non-linear simplex optimization. The heat conduction problem is solved utilizing the boundary element method, which calculates the difference between the measured temperature at the exposed surface and the computed temperature under the current update of the unknown subsurface flaws and cavities. In a first step, clusters of singularities are utilized to solve the inverse problem and to identify the location of the centroid(s) of the subsurface cavity(ies)/flaw(s). In a second step, the reconstruction of the estimated cavity(ies)/flaw(s) geometry(ies) is accomplished by utilizing an anchored grid pattern upon which cubic spline knots are restricted to move in the search for unknown geometry. Solution of the inverse problem is achieved using a genetic algorithm accelerated with the Nelder-Mead non-linear simplex. To optimize the cubic spline interpolated geometry, the flux (Neumann) boundary conditions are minimized using a least squares functional. The automated algorithm successfully reconstructs single and multiple subsurface cavities within two dimensional mediums. The solver is also shown to accurately predict cavity geometries with random noise in the boundary condition measurements. Subsurface cavities can be difficult to detect based on their location. By applying different boundary conditions to the same geometry, more information is supplied at the boundary, and the subsurface cavity is easily detected despite its low heat signature effect at the boundaries. Extensions to three-dimensional applications are outlined.
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Date Issued: 2013
Identifier: CFE0004900, ucf:49644
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004900

Title: Impacts of Complexity and Timing of Communication Interruptions on Visual Detection Tasks.
Creator: Stader, Sally, Mouloua, Mustapha, Hancock, Peter, Neider, Mark, Kincaid, John, University of Central Florida
Abstract / Description: Auditory preemption theory suggests two competing assumptions for the attention-capturing and performance-altering properties of auditory tasks. In onset preemption, attention is immediately diverted to the auditory channel. Strategic preemption involves a decision process in which the operator maintains focus on more complex auditory messages. The limitation in this process is that the human auditory, or echoic, memory store has a limit of 2 to 5 seconds, after which the message must be...
Show moreAuditory preemption theory suggests two competing assumptions for the attention-capturing and performance-altering properties of auditory tasks. In onset preemption, attention is immediately diverted to the auditory channel. Strategic preemption involves a decision process in which the operator maintains focus on more complex auditory messages. The limitation in this process is that the human auditory, or echoic, memory store has a limit of 2 to 5 seconds, after which the message must be processed or it decays. In contrast, multiple resource theory suggests that visual and auditory tasks may be efficiently time-shared because two different pools of cognitive resources are used. Previous research regarding these competing assumptions has been limited and equivocal. Thus, the current research focused on systematically examining the effects of complexity and timing of communication interruptions on visual detection tasks. It was hypothesized that both timing and complexity levels would impact detection performance in a multi-task environment. Study 1 evaluated the impact of complexity and timing of communications occurring before malfunctions in an ongoing visual detection task. Twenty-four participants were required to complete each of the eight timing blocks that included simple or complex communications occurring simultaneously, and at 2, 5, or 8 seconds before detection events. For simple communications, participants repeated three pre-recorded words. However, for complex communications, they generated three words beginning with the same last letter of a word prompt. Results indicated that complex communications at two seconds or less occurring before a visual detection event significantly impacted response time with a 1.3 to 1.6 second delay compared to all the other timings. Detection accuracy for complex communication tasks under the simultaneous condition was significantly degraded compared to simple communications at five seconds or more prior to the task. This resulted in a 20% decline in detection accuracy. Additionally, participants' workload ratings for complex communications were significantly higher than simple communications. Study 2 examined the timing of communications occurring at the corresponding seconds after the visual detection event. Twenty-four participants were randomly assigned to the communication complexity and timing blocks as in study 1. The results did not find significant performance effects of timing or complexity of communications on detection performance. However the workload ratings for the 2 and 5 second complex communication presentations were higher compared to the same simple communication conditions. Overall, these findings support the strategic preemption assumption for well-defined, complex communications. The onset preemption assumption for simple communications was not supported. These results also suggest that the boundaries of the multiple resource theory assumption may exist up to the limits of the echoic memory store. Figures of merit for task performance under the varying levels of timing and complexity are presented. Several theoretical and practical implications are discussed.
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Date Issued: 2014
Identifier: CFE0005420, ucf:50415
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005420

Title: Investigating the universality and comprehensive ability of measures to assess the state of workload.
Creator: Abich, Julian, Reinerman, Lauren, Lackey, Stephanie, Szalma, James, Taylor, Grant, University of Central Florida
Abstract / Description: Measures of workload have been developed on the basis of the various definitions, some are designed to capture the multi-dimensional aspects of a unitary resource pool (Kahneman, 1973) while others are developed on the basis of multiple resource theory (Wickens, 2002). Although many theory based workload measures exist, others have often been constructed to serve the purpose of specific experimental tasks. As a result, it is likely that not every workload measure is reliable and valid for all...
Show moreMeasures of workload have been developed on the basis of the various definitions, some are designed to capture the multi-dimensional aspects of a unitary resource pool (Kahneman, 1973) while others are developed on the basis of multiple resource theory (Wickens, 2002). Although many theory based workload measures exist, others have often been constructed to serve the purpose of specific experimental tasks. As a result, it is likely that not every workload measure is reliable and valid for all tasks, much less each domain. To date, no single measure, systematically tested across experimental tasks, domains, and other measures is considered a universal measure of workload. Most researchers would argue that multiple measures from various categories should be applied to a given task to comprehensively assess workload. The goal for Study 1 to establish task load manipulations for two theoretically different tasks that induce distinct levels of workload assessed by both subjective and performance measures was successful. The results of the subjective responses support standardization and validation of the tasks and demands of that task for investigating workload. After investigating the use of subjective and objective measures of workload to identify a universal and comprehensive measure or set of measures, based on Study 2, it can only be concluded that not one or a set of measures exists. Arguably, it is not to say that one will never be conceived and developed, but at this time, one does not reside in the psychometric catalog. Instead, it appears that a more suitable approach is to customize a set of workload measures based on the task. The novel approach of assessing the sensitivity and comprehensive ability of conjointly utilizing subjective, performance, and physiological workload measures for theoretically different tasks within the same domain contributes to the theory by laying the foundation for improving methodology for researching workload. The applicable contribution of this project is a stepping-stone towards developing complex profiles of workload for use in closed-loop systems, such as human-robot team interaction. Identifying the best combination of workload measures enables human factors practitioners, trainers, and task designers to improve methodology and evaluation of system designs, training requirements, and personnel selection.
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Date Issued: 2013
Identifier: CFE0005119, ucf:50675
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005119

Title: On Distributed Estimation for Resource Constrained Wireless Sensor Networks.
Creator: Sani, Alireza, Vosoughi, Azadeh, Rahnavard, Nazanin, Wei, Lei, Atia, George, Chatterjee, Mainak, University of Central Florida
Abstract / Description: We study Distributed Estimation (DES) problem, where several agents observe a noisy version of an underlying unknown physical phenomena (which is not directly observable), and transmit a compressed version of their observations to a Fusion Center (FC), where collective data is fused to reconstruct the unknown. One of the most important applications of Wireless Sensor Networks (WSNs) is performing DES in a field to estimate an unknown signal source. In a WSN battery powered geographically...
Show moreWe study Distributed Estimation (DES) problem, where several agents observe a noisy version of an underlying unknown physical phenomena (which is not directly observable), and transmit a compressed version of their observations to a Fusion Center (FC), where collective data is fused to reconstruct the unknown. One of the most important applications of Wireless Sensor Networks (WSNs) is performing DES in a field to estimate an unknown signal source. In a WSN battery powered geographically distributed tiny sensors are tasked with collecting data from the field. Each sensor locally processes its noisy observation (local processing can include compression,dimension reduction, quantization, etc) and transmits the processed observation over communication channels to the FC, where the received data is used to form a global estimate of the unknown source such that the Mean Square Error (MSE) of the DES is minimized. The accuracy of DES depends on many factors such as intensity of observation noises in sensors, quantization errors in sensors, available power and bandwidth of the network, quality of communication channels between sensors and the FC, and the choice of fusion rule in the FC. Taking into account all of these contributing factors and implementing a DES system which minimizes the MSE and satisfies all constraints is a challenging task. In order to probe into different aspects of this challenging task we identify and formulate the following three problems and address them accordingly:1- Consider an inhomogeneous WSN where the sensors' observations is modeled linear with additive Gaussian noise. The communication channels between sensors and FC are orthogonal power and bandwidth-constrained erroneous wireless fading channels. The unknown to be estimated is a Gaussian vector. Sensors employ uniform multi-bit quantizers and BPSK modulation. Given this setup, we ask: what is the best fusion rule in the FC? what is the best transmit power and quantization rate (measured in bits per sensor) allocation schemes that minimize the MSE? In order to answer these questions, we derive some upper bounds on global MSE and through minimizing those bounds, we propose various resource allocation schemes for the problem, through which we investigate the effect of contributing factors on the MSE.2- Consider an inhomogeneous WSN with an FC which is tasked with estimating a scalar Gaussian unknown. The sensors are equipped with uniform multi-bit quantizers and the communication channels are modeled as Binary Symmetric Channels (BSC). In contrast to former problem the sensors experience independent multiplicative noises (in addition to additive noise). The natural question in this scenario is: how does multiplicative noise affect the DES system performance? how does it affect the resource allocation for sensors, with respect to the case where there is no multiplicative noise? We propose a linear fusion rule in the FC and derive the associated MSE in closed-form. We propose several rate allocation schemes with different levels of complexity which minimize the MSE. Implementing the proposed schemes lets us study the effect of multiplicative noise on DES system performance and its dynamics. We also derive Bayesian Cramer-Rao Lower Bound (BCRLB) and compare the MSE performance of our porposed methods against the bound.As a dual problem we also answer the question: what is the minimum required bandwidth of thenetwork to satisfy a predetermined target MSE?3- Assuming the framework of Bayesian DES of a Gaussian unknown with additive and multiplicative Gaussian noises involved, we answer the following question: Can multiplicative noise improve the DES performance in any case/scenario? the answer is yes, and we call the phenomena as 'enhancement mode' of multiplicative noise. Through deriving different lower bounds, such as BCRLB,Weiss-Weinstein Bound (WWB), Hybrid CRLB (HCRLB), Nayak Bound (NB), Yatarcos Bound (YB) on MSE, we identify and characterize the scenarios that the enhancement happens. We investigate two situations where variance of multiplicative noise is known and unknown. Wealso compare the performance of well-known estimators with the derived bounds, to ensure practicability of the mentioned enhancement modes.
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Date Issued: 2017
Identifier: CFE0006913, ucf:51698
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006913

Title: SPRAY COOLING FOR LAND, SEA, AIR AND SPACE BASED APPLICATIONS,A FLUID MANAGEMENT SYSTEM FOR MULTIPLE NOZZLE SPRAY COOLING AND A GUIDE TO HIGH HEAT FLUX HEATER DESIGN.
Creator: Glassman, Brian, Chow, Louis, University of Central Florida
Abstract / Description: This thesis is divided into four distinct chapters all linked by the topic of spray cooling. Chapter one gives a detailed categorization of future and current spray cooling applications, and reviews the major advantages and disadvantages that spray cooling has over other high heat flux cooling techniques. Chapter two outlines the developmental goals of spray cooling, which are to increase the output of a current system and to enable new technologies to be technically feasible. Furthermore,...
Show moreThis thesis is divided into four distinct chapters all linked by the topic of spray cooling. Chapter one gives a detailed categorization of future and current spray cooling applications, and reviews the major advantages and disadvantages that spray cooling has over other high heat flux cooling techniques. Chapter two outlines the developmental goals of spray cooling, which are to increase the output of a current system and to enable new technologies to be technically feasible. Furthermore, this chapter outlines in detail the impact that land, air, sea, and space environments have on the cooling system and what technologies could be enabled in each environment with the aid of spray cooling. In particular, the heat exchanger, condenser and radiator are analyzed in their corresponding environments. Chapter three presents an experimental investigation of a fluid management system for a large area multiple nozzle spray cooler. A fluid management or suction system was used to control the liquid film layer thickness needed for effective heat transfer. An array of sixteen pressure atomized spray nozzles along with an imbedded fluid suction system was constructed. Two surfaces were spray tested one being a clear grooved Plexiglas plate used for visualization and the other being a bottom heated grooved 4.5 x 4.5 cm2 copper plate used to determine the heat flux. The suction system utilized an array of thin copper tubes to extract excess liquid from the cooled surface. Pure water was ejected from two spray nozzle configurations at flow rates of 0.7 L/min to 1 L/min per nozzle. It was found that the fluid management system provided fluid removal efficiencies of 98% with a 4-nozzle array, and 90% with the full 16-nozzle array for the downward spraying orientation. The corresponding heat fluxes for the 16 nozzle configuration were found with and without the aid of the fluid management system. It was found that the fluid management system increased heat fluxes on the average of 30 W/cm2 at similar values of superheat. Unfortunately, the effectiveness of this array at removing heat at full levels of suction is approximately 50% & 40% of a single nozzle at respective 10„aC & 15„aC values of superheat. The heat transfer data more closely resembled convective pooling boiling. Thus, it was concluded that the poor heat transfer was due to flooding occurring which made the heat transfer mechanism mainly forced convective boiling and not spray cooling. Finally, Chapter four gives a detailed guide for the design and construction of a high heat flux heater for experimental uses where accurate measurements of surface temperatures and heat fluxes are extremely important. The heater designs presented allow for different testing applications; however, an emphasis is placed on heaters designed for use with spray cooling.
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Date Issued: 2005
Identifier: CFE0000473, ucf:46351
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000473

Title: THE RELATIONSHIP BETWEEN GENRE CHOICE OF MUSIC AND ALTRUISTIC BEHAVIOR.
Creator: Hippler, Christine, Whitten, Shannon, University of Central Florida
Abstract / Description: ABSTRACT Extensive research has documented the relationship between listening to certain genres of music and negative effects on social behavior such as aggressive and antisocial behavior. The present study explored whether there are genres of music associated with altruism. Altruistic behavior is defined as behavior that is consistently more caring, helpful, considerate of other's feelings, and self- sacrificing. These behaviors promote our ability to thrive as a community. Yet, few studies...
Show moreABSTRACT Extensive research has documented the relationship between listening to certain genres of music and negative effects on social behavior such as aggressive and antisocial behavior. The present study explored whether there are genres of music associated with altruism. Altruistic behavior is defined as behavior that is consistently more caring, helpful, considerate of other's feelings, and self- sacrificing. These behaviors promote our ability to thrive as a community. Yet, few studies have addressed the relationship between music and altruism. Data was collected from 608 college students who completed a self-report altruism scale, music preference measure, the Marlowe Crowne social desirability scale, and a demographic information form in order to see if there is a relationship between choice of music and altruism. A multiple hierarchal regression analysis found music genre choice accounted for 15.9 percent of variance in self-reported altruism. Significant, positive correlations emerged also between altruism and several music genres including alternative, country, classical, and emo.
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Date Issued: 2011
Identifier: CFH0003820, ucf:44753
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0003820

workload (3)	+ -
Elementary (2)	+ -
Multiple Linear Regression (2)	+ -
Multiple Resource Theory (2)	+ -
multiple group membership (2)	+ -

multiple regression (2)	+ -
multiple resource theory (2)	+ -
Activities of Daily Living (1)	+ -
Altruism (1)	+ -
Audition (1)	+ -
Aurora (1)	+ -
Autism (1)	+ -
Before-After Analysis (1)	+ -
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Black students (1)	+ -
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COVIS (1)	+ -
Camera Calibration (1)	+ -
Carthage (1)	+ -
Christine Hippler (1)	+ -
Christine Lynn Hippler (1)	+ -
Cluster Analysis (1)	+ -
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