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Title: ANCHORING ENERGY AND PRETILT ANGLE EFFECTS ON LIQUID CRYSTAL RESPONSE TIME.
Creator: Nie, Xiangyi, Wu, Shin-Tson, University of Central Florida
Abstract / Description: This dissertation covers some important topics on the liquid crystal-substrate surface effects, including theoretical derivations and confirming experimental results. The research work is expected to make important impacts on liquid crystal device designs and to open new doors for further research along these topics. In this dissertation, a novel high-electric-field technique is developed to characterize the anchoring energy of vertically-aligned liquid crystal cells. Both theoretical...
Show moreThis dissertation covers some important topics on the liquid crystal-substrate surface effects, including theoretical derivations and confirming experimental results. The research work is expected to make important impacts on liquid crystal device designs and to open new doors for further research along these topics. In this dissertation, a novel high-electric-field technique is developed to characterize the anchoring energy of vertically-aligned liquid crystal cells. Both theoretical analyses and confirming experimental results are presented. Vertically-aligned liquid crystal cells with buffed polyimide alignment layers are used to validate the measurement techniques. Based on the voltage-dependent transmittance of the liquid crystal cells, a linear fitting can be obtained, which leads to a precise determination of the anchoring energy. If some specific liquid crystal material parameters are known, then the traditional cell capacitance measurements can be avoided. Anchoring energy and cell gap effects on liquid crystal response time is theoretically analyzed and experimentally investigated. A novel theory on the liquid crystal dynamics is developed. In this part, two different theoretical approaches are discussed: one is surface dynamic equation method and the other is effective cell gap method. These two different approaches lead to consistent results, which are also confirmed by our experimental results. This work opens a new door for LCD industry to optimize liquid crystal response time, and it is especially critical for liquid crystal cells with thin cell gap, which is a promising approach for fast response time liquid crystal display. Pretilt angle effects on liquid crystal dynamics are analyzed theoretically and validated experimentally. Analytical expressions are derived to describe liquid crystal response time under nonzero pretilt angle conditions. The theoretical analysis is confirmed experimentally using vertically-aligned liquid crystal cells. These results quantitatively correlate pretilt angles with liquid crystal response time, which is important for optimizing liquid crystal response time.
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Date Issued: 2007
Identifier: CFE0001927, ucf:47440
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001927

Title: IMAGE-SPACE APPROACH TO REAL-TIME REALISTIC RENDERING.
Creator: Shah, Musawir, Pattanaik, Sumanta, University of Central Florida
Abstract / Description: One of the main goals of computer graphics is the fast synthesis of photorealistic image of virtual 3D scenes. The work presented in this thesis addresses this goal of speed and realism. In real-time realistic rendering, we encounter certain problems that are difficult to solve in the traditional 3-dimensional geometric space. We show that using an image-space approach can provide effective solutions to these problems. Unlike geometric space algorithms that operate on 3D primitives such as...
Show moreOne of the main goals of computer graphics is the fast synthesis of photorealistic image of virtual 3D scenes. The work presented in this thesis addresses this goal of speed and realism. In real-time realistic rendering, we encounter certain problems that are difficult to solve in the traditional 3-dimensional geometric space. We show that using an image-space approach can provide effective solutions to these problems. Unlike geometric space algorithms that operate on 3D primitives such as points, edges, and polygons, image-space algorithms operate on 2D snapshot images of the 3D geometric data. Operating in image-space effectively decouples the geometric complexity of the 3D data from the run-time of the rendering algorithm. Other important advantages of image-space algorithms include ease of implementation on modern graphics hardware, and fast computation of approximate solutions to certain lighting calculations. We have applied the image-space approach and developed algorithms for three prominent problems in real-time realistic rendering, namely, representing and lighting large 3D scenes in the context of grass rendering, rendering caustics, which is a complex indirect illumination effect, and subsurface scattering for rendering of translucent objects.
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Date Issued: 2007
Identifier: CFE0001967, ucf:47462
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001967

Title: EFFECTS OF VOLUNTARY CONTROL ON PERFORMANCE RESPONSE UNDER STRESS.
Creator: Morris, Christina Shawn, Hancock, Peter A., University of Central Florida
Abstract / Description: Recent stressful environments within military and non-military domains are producing a new challenge for the lab-based study of stress on task performance, one that requires knowledge of underlying cognitive-motivational and goal orientation factors. Results of recent stress on task performance research traditionally employ metaphorical explanations (i.e., resource theory) in order to rapidly apply stimulus-response outcomes to the real world counterparts. This dissertation provides an...
Show moreRecent stressful environments within military and non-military domains are producing a new challenge for the lab-based study of stress on task performance, one that requires knowledge of underlying cognitive-motivational and goal orientation factors. Results of recent stress on task performance research traditionally employ metaphorical explanations (i.e., resource theory) in order to rapidly apply stimulus-response outcomes to the real world counterparts. This dissertation provides an alternative perspective about these metaphorical, or black box, interpretations and reveals how they may be confounded with respect to the intended real world counterpart. To examine how voluntary human control can influence traditional stress/no-stress research findings, traditional as well as exploratory paradigms were presented. Both noise and time pressure conditions produced significant differences between experimental and control groups on visual discrimination. However, when analogous cash payment-contingency conditions were employed, the traditional stress/no-stress findings were not evident. In addition, a second experiment revealed that this trend of differences (and non-differences) held consistently over 30 minutes of interrupted task performance time. This study indicates the importance of developing more diagnostic measures that include assessments of how the differences between participants' and the generalized operators' goals and motivations may alter results in stressful task environments.
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Date Issued: 2004
Identifier: CFE0000019, ucf:46134
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000019

Title: ANALYSIS OF AIRCRAFT ARRIVAL DELAY AND AIRPORT ON-TIME PERFORMANCE.
Creator: Bai, Yuqiong, Abdel-Aty, Mohamed, University of Central Florida
Abstract / Description: In this research, statistical models of airport delay and single flight arrival delay were developed. The models use the Airline On-Time Performance Data from the Federal Aviation Administration (FAA) and the Surface Airways Weather Data from the National Climatic Data Center (NCDC). Multivariate regression, ANOVA, neural networks and logistic regression were used to detect the pattern of airport delay, aircraft arrival delay and schedule performance. These models are then integrated in the...
Show moreIn this research, statistical models of airport delay and single flight arrival delay were developed. The models use the Airline On-Time Performance Data from the Federal Aviation Administration (FAA) and the Surface Airways Weather Data from the National Climatic Data Center (NCDC). Multivariate regression, ANOVA, neural networks and logistic regression were used to detect the pattern of airport delay, aircraft arrival delay and schedule performance. These models are then integrated in the form of a system for aircraft delay analysis and airport delay assessment. The assessment of an airport¡¯s schedule performance is discussed. The results of the research show that the daily average arrival delay at Orlando International Airport (MCO) is highly related to the departure delay at other airports. The daily average arrival delay can also be used to evaluate the delay performance at MCO. The daily average arrival delay at MCO is found to show seasonal and weekly patterns, which is related to the schedule performance. The precipitation and wind speed are also found contributors to the arrival delay. The capacity of the airport is not found to be significant. This may indicate that the capacity constraint is not an important problem at MCO. This research also investigated the delays at the flight level, including the flights with delay ¡Ý0 minute and the flights with delay ¡Ý15min, which provide the delay pattern of single arrival flights. The characteristics of single flight and their effect on flight delay are considered. The precipitation, flight distance, season, weekday, arrival time and the time spacing between two successive arriving flights are found to contribute to the arrival delay. We measure the time interval of two consecutive flights spacing and analyze its effect on the flight delay and find that for a positively delayed flight, as the time space increases, the probability of the flights being delayed will decrease. While it was possible to calculate the immediate impact of originating delays, it is not possible to calculate their impact on the cumulative delay. If a late departing aircraft has no empty space in its down line schedule, it will continue to be late. If that aircraft enters a connecting airport, it can pass its lateness on to another aircraft. In the research we also consider purifying only the arrival delay at MCO, excluding the flights with originating delay >0. The model makes it possible to identify the pattern of the aircraft arrival delay. The weather conditions are found to be the most significant factors that influence the arrival delay due to the destination airport.
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Date Issued: 2006
Identifier: CFE0001049, ucf:46808
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001049

Title: A COMPARISON OF TRADITIONAL AND NONTRADITIONAL COLLEGE STUDENTS' STRESS AND ITS RELATIONSHIP TO THEIR TIME MANAGEMENT AND OVERALL PSYCHOLOGICAL ADJUSTMENT.
Creator: Stagman, Debra, Mottarella, Karen, University of Central Florida
Abstract / Description: The academic demands of college can be strenuous. Nontraditional students in particular may be at risk for role conflict and overload. This study examines levels of academic stressors and reactions to stressors between traditional and nontraditional undergraduate college students in order to investigate the relationships between academic stress, time management behaviors and overall psychological adjustment between the two groups. Participants completed Gadzella's (1991) Student-Life Stress...
Show moreThe academic demands of college can be strenuous. Nontraditional students in particular may be at risk for role conflict and overload. This study examines levels of academic stressors and reactions to stressors between traditional and nontraditional undergraduate college students in order to investigate the relationships between academic stress, time management behaviors and overall psychological adjustment between the two groups. Participants completed Gadzella's (1991) Student-Life Stress Inventory, Time Management Behaviors Scale (Macan, Shahani, Dipboye, & Phillips, 1990) and the Symptom Checklist-90 Revised (Derogatis, 1994). Results reveal significant differences between traditional and nontraditional students on a subscale of the Time Management Behavior Scale measuring the ability to set goals and prioritize. Additionally, a marginally significant difference between traditional and nontraditional students was found on another subscale of the Time Management Behavior Scale measuring the mechanics of time management. These results indicate students who maintain multiple life-roles and responsibilities in addition to their role of college student are better at identifying and setting goals that need to be accomplished and prioritizing the tasks required to meet these goals. Furthermore, these students may be more adept at the mechanics involved with time management such as making list and scheduling activities in advance.
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Date Issued: 2011
Identifier: CFH0003818, ucf:44729
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0003818

Title: IGNITION STUDIES OF DIISOPROPYL KETONE, A SECOND-GENERATION BIOFUEL.
Creator: Pryor, Owen, Vasu, Subith, University of Central Florida
Abstract / Description: This thesis focuses on ignition of diisopropyl ketone (DIPK), a new biofuel candidate that is produced by endophytic conversion. The ignition delay times behind reflected shockwaves were modeled in a high-pressure shock tube. The ignition delay times were compared to other biofuels and gasoline surrogates. Parametric studies of the ignition delay experiments were performed between 1-10 atm and 900 -1200K. An OH optical sensor was developed in conjunction for the ignition delay experiments....
Show moreThis thesis focuses on ignition of diisopropyl ketone (DIPK), a new biofuel candidate that is produced by endophytic conversion. The ignition delay times behind reflected shockwaves were modeled in a high-pressure shock tube. The ignition delay times were compared to other biofuels and gasoline surrogates. Parametric studies of the ignition delay experiments were performed between 1-10 atm and 900 -1200K. An OH optical sensor was developed in conjunction for the ignition delay experiments. The OH optical sensor uses a microwave discharge lamp to generate light at 308 nm that will then be shined through the combustion reaction. Using Beer-Lambert law the concentration of OH can be obtained during ignition and oxidation of hydrocarbon fuels in a shock tube. DIPK ignition delay time experiments are planned in two shock tubes (located at UCF and UF) to provide ignition and OH time-histories data for model validation.
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Date Issued: 2014
Identifier: CFH0004635, ucf:45253
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004635

Title: A PRELIMINARY STUDY FOR ESTIMATING POSTMORTEM INTERVAL OF FABRIC DEGRADATION IN CENTRAL FLORIDA.
Creator: Humbert, Lorraine, Schultz, John, University of Central Florida
Abstract / Description: Forensic anthropologists rely on forensic evidence to estimate the postmortem interval of a decedent. This may include the study of the degree of deterioration of the human body, the life stage of insects, and the degradation of associated material evidence. Material evidence comes in many forms, and certain taphonomic processes will affect the material and must be considered when making inferences about a PMI. These include variables such as the characteristics of the soil, microorganisms,...
Show moreForensic anthropologists rely on forensic evidence to estimate the postmortem interval of a decedent. This may include the study of the degree of deterioration of the human body, the life stage of insects, and the degradation of associated material evidence. Material evidence comes in many forms, and certain taphonomic processes will affect the material and must be considered when making inferences about a PMI. These include variables such as the characteristics of the soil, microorganisms, and the presence of a decaying organic material. Previous research has undertaken studies in how fabric degrades over time; however, there is no standard methodology in use. The purpose of this research project is to establish a comprehensive scoring system and description standard after analyzing the degradation of four different fabric types. This will be useful for future studies in need of a standard methodology. In addition, the methods used in this project can be applied to actual forensic cases. After retrieval, the fabric type with the highest degradation was the cotton with about 1/3 of all cotton fabric swatches demonstrating more than 50% total degradation. For all fabric types, swatches that were positioned flat tended to degrade more than those that were positioned crumpled. Cotton fabric swatches degraded more in Trench 1 and Trench 2 than the Ground Surface, however, all other fabric types demonstrated slightly more degradation on the Ground Surface than the other two Areas. Soil moisture fluctuated the most on the Ground Surface while Trench 1 and Trench 2 were able to retain more water in the soil. Overall, cotton was the only fabric type to degrade significantly enough to show how it degrades over time, while the other fabric types have longer degradation intervals that must be studied further.
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Date Issued: 2013
Identifier: CFH0004515, ucf:45220
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004515

Title: APPEARANCE-DRIVEN MATERIAL DESIGN.
Creator: Colbert, Mark, Hughes, Charles, University of Central Florida
Abstract / Description: In the computer graphics production environment, artists often must tweak specific lighting and material parameters to match a mind's eye vision of the appearance of a 3D scene. However, the interaction between a material and a lighting environment is often too complex to cognitively predict without visualization. Therefore, artists operate in a design cycle, where they tweak the parameters, wait for a visualization, and repeat, seeking to obtain a desired look. We propose the use of...
Show moreIn the computer graphics production environment, artists often must tweak specific lighting and material parameters to match a mind's eye vision of the appearance of a 3D scene. However, the interaction between a material and a lighting environment is often too complex to cognitively predict without visualization. Therefore, artists operate in a design cycle, where they tweak the parameters, wait for a visualization, and repeat, seeking to obtain a desired look. We propose the use of appearance-driven material design. Here, artists directly design the appearance of reflected light for a specific view, surface point, and time. In this thesis, we discuss several methods for appearance-driven design with homogeneous materials, spatially-varying materials, and appearance-matching materials, where each uses a unique modeling and optimization paradigm. Moreover, we present a novel treatment of the illumination integral using sampling theory that can utilize the computational power of the graphics processing unit (GPU) to provide real-time visualization of the appearance of various materials illuminated by complex environment lighting. As a system, the modeling, optimization and rendering steps all operate on arbitrary geometry and in detailed lighting environments, while still providing instant feedback to the designer. Thus, our approach allows materials to play an active role in the process of set design and story-telling, a capability that was, until now, difficult to achieve due to the unavailability of interactive tools appropriate for artists.
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Date Issued: 2008
Identifier: CFE0002217, ucf:47913
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002217

Title: A mixed-methods approach to understanding the relationship between mental toughness and the effect of music on exercise performance.
Creator: Baker, Kayla, Garcia, Jeanette, Stout, Jeffrey, Fukuda, David, Fisher, Thomas, Dawson, Nicole, University of Central Florida
Abstract / Description: Previous research has investigated the use of music as an ergogenic aid for exercise performance; however, the effect of music on exercise may differ between individuals of varying levels of mental toughness (MT). Purpose: The purpose of this study is to examine the moderating effect of MT on the effect of listening to music during exercise. Methods: The current study used a counter-balanced design, utilizing a mixed-methods approach. Thirty-one recreationally-active individuals (22.13 (&)...
Show morePrevious research has investigated the use of music as an ergogenic aid for exercise performance; however, the effect of music on exercise may differ between individuals of varying levels of mental toughness (MT). Purpose: The purpose of this study is to examine the moderating effect of MT on the effect of listening to music during exercise. Methods: The current study used a counter-balanced design, utilizing a mixed-methods approach. Thirty-one recreationally-active individuals (22.13 (&)#177; 2.11 yrs, 1.73 (&)#177; .10 m, 75.68 (&)#177; 14.67 kg, 42.89 (&)#177; 5.31 mL(&)#183;kg(&)#183;min-1; 65.5% males) were recruited for this study. Participants completed an initial visit to complete a MT questionnaire and create a personalized music playlist of at least 15 songs. Participants completed two familiarization trials and a VO2max test on the treadmill, all on separate days. The experimental trials consisted of two separate conditions: 1) no music (NM); and 2) self-selected music (SSM). For each experimental trial, participants performed a time-to-exhaustion (TTE) run at 80% of their VO2max, separated by at least 48 hours, followed by a post-study interview. Pearson product-moment correlations were used to investigate relationships between performance variables and MT. Moderated regression analysis was used to determine a potential order effect, as well as a potential moderating effect of MT on change in performance between NM and SSM groups. Linear regression analysis was used to determine a potential relationship between MT and change in performance between NM and SSM groups. An alpha level of p ? 0.05 was used to determine statistical significance. All qualitative data from post-study interviews was transcribed, coded, and categorized into primary themes. All statistical analyses was conducted via the Statistical Package for Social Science (SPSS) software for Windows version 21 (SPSS Inc., Chicago, IL). Results: Averages were calculated for MT (156.39 (&)#177; 9.38), TTESSM (14.18 (&)#177; 4.79 minutes), and TTENM (12.23 (&)#177; 5.24 minutes). Correlations were found between VO2max and TTESSM, TTENM, and MT (r = 0.390, p = 0.030; r = 0.519, p = 0.003; r = 0.404, p = 0.024; respectively). Moderated regression analysis revealed a non-significant interaction between MT, music, and order, indicating no order effect (? = -0.416, p = 0.735). Independent samples t-tests revealed no significant difference in MT, performance, or VO2maz between groups of participants who received music first or music second, indicating no effect of order (F = 0.388; p = 0.538; F = 0.537; p = 0.470; F = 0.070; p = 0.794; respectively. Moderated regression analysis, via linear regression, determined no significant moderating effect of MT on the change in performance between trials (?TTE) (F (3, 58) = 0.958, r = 0.217, p = 0.498). Linear regression, however, revealed a significant main effect of MT, indicating an inverse relationship between MT and ?TTE (F (1, 29) = 4.417, r = -0.634, p = 0.044). Discussion: The results from the current study indicate that greater levels of MT were associated with less change between the two performance trials, however, there were no significant relationships between MT or performance with self-selected music. This finding suggests that individuals with greater MT may demonstrate consistent patterns of performance, irrespective of the presence of external factors. Understanding the effects of MT and how external and internal stimuli affect performance may allow exercise professionals to tailor their training or rehabilitation programs to each individual, therefore increasing exercise performance and adherence.
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Date Issued: 2019
Identifier: CFE0007428, ucf:52736
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007428

Title: Leaning Robust Sequence Features via Dynamic Temporal Pattern Discovery.
Creator: Hu, Hao, Wang, Liqiang, Zhang, Shaojie, Liu, Fei, Qi, GuoJun, Zhou, Qun, University of Central Florida
Abstract / Description: As a major type of data, time series possess invaluable latent knowledge for describing the real world and human society. In order to improve the ability of intelligent systems for understanding the world and people, it is critical to design sophisticated machine learning algorithms for extracting robust time series features from such latent knowledge. Motivated by the successful applications of deep learning in computer vision, more and more machine learning researchers put their attentions...
Show moreAs a major type of data, time series possess invaluable latent knowledge for describing the real world and human society. In order to improve the ability of intelligent systems for understanding the world and people, it is critical to design sophisticated machine learning algorithms for extracting robust time series features from such latent knowledge. Motivated by the successful applications of deep learning in computer vision, more and more machine learning researchers put their attentions on the topic of applying deep learning techniques to time series data. However, directly employing current deep models in most time series domains could be problematic. A major reason is that temporal pattern types that current deep models are aiming at are very limited, which cannot meet the requirement of modeling different underlying patterns of data coming from various sources. In this study we address this problem by designing different network structures explicitly based on specific domain knowledge such that we can extract features via most salient temporal patterns. More specifically, we mainly focus on two types of temporal patterns: order patterns and frequency patterns. For order patterns, which are usually related to brain and human activities, we design a hashing-based neural network layer to globally encode the ordinal pattern information into the resultant features. It is further generalized into a specially designed Recurrent Neural Networks (RNN) cell which can learn order patterns in an online fashion. On the other hand, we believe audio-related data such as music and speech can benefit from modeling frequency patterns. Thus, we do so by developing two types of RNN cells. The first type tries to directly learn the long-term dependencies on frequency domain rather than time domain. The second one aims to dynamically filter out the ``noise" frequencies based on temporal contexts. By proposing various deep models based on different domain knowledge and evaluating them on extensive time series tasks, we hope this work can provide inspirations for others and increase the community's interests on the problem of applying deep learning techniques to more time series tasks.
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Date Issued: 2019
Identifier: CFE0007470, ucf:52679
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007470

Title: Managing IO Resource for Co-running Data Intensive Applications in Virtual Clusters.
Creator: Huang, Dan, Wang, Jun, Zhou, Qun, Sun, Wei, Zhang, Shaojie, Wang, Liqiang, University of Central Florida
Abstract / Description: Today Big Data computer platforms employ resource management systems such as Yarn, Torque, Mesos, and Google Borg to enable sharing the physical computing among many users or applications. Given virtualization and resource management systems, users are able to launch their applications on the same node with low mutual interference and management overhead on CPU and memory. However, there are still challenges to be addressed before these systems can be fully adopted to manage the IO resources...
Show moreToday Big Data computer platforms employ resource management systems such as Yarn, Torque, Mesos, and Google Borg to enable sharing the physical computing among many users or applications. Given virtualization and resource management systems, users are able to launch their applications on the same node with low mutual interference and management overhead on CPU and memory. However, there are still challenges to be addressed before these systems can be fully adopted to manage the IO resources in Big Data File Systems (BDFS) and shared network facilities. In this study, we mainly study on three IO management problems systematically, in terms of the proportional sharing of block IO in container-based virtualization, the network IO contention in MPI-based HPC applications and the data migration overhead in HPC workflows. To improve the proportional sharing, we develop a prototype system called BDFS-Container, by containerizing BDFS at Linux block IO level. Central to BDFS-Container, we propose and design a proactive IOPS throttling based mechanism named IOPS Regulator, which improves proportional IO sharing under the BDFS IO pattern by 74.4% on an average. In the aspect of network IO resource management, we exploit using virtual switches to facilitate network traffic manipulation and reduce mutual interference on the network for in-situ applications. In order to dynamically allocate the network bandwidth when it is needed, we adopt SARIMA-based techniques to analyze and predict MPI traffic issued from simulations. Third, to solve the data migration problem in small-medium sized HPC clusters, we propose to construct a sided IO path, named as SideIO, to explicitly direct analysis data to BDFS that co-locates computation with data. By experimenting with two real-world scientific workflows, SideIO completely avoids the most expensive data movement overhead and achieves up to 3x speedups compared with current solutions.
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Date Issued: 2018
Identifier: CFE0007195, ucf:52268
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007195

Title: Development of Decision Support System for Active Traffic Management Systems Considering Travel Time Reliability.
Creator: Chung, Whoibin, Abdel-Aty, Mohamed, Eluru, Naveen, Hasan, Samiul, Cai, Qing, Huang, Hsin-Hsiung, University of Central Florida
Abstract / Description: As traffic problems on roadways have been increasing, active traffic management systems (ATM) using proactive traffic management concept have been deployed on freeways and arterials. The ATM aims to integrate and automate various traffic control strategies such as variable speed limits, queue warning, and ramp metering through a decision support system (DSS). Over the past decade, there have been many efforts to integrate freeways and arterials for the efficient operation of roadway networks....
Show moreAs traffic problems on roadways have been increasing, active traffic management systems (ATM) using proactive traffic management concept have been deployed on freeways and arterials. The ATM aims to integrate and automate various traffic control strategies such as variable speed limits, queue warning, and ramp metering through a decision support system (DSS). Over the past decade, there have been many efforts to integrate freeways and arterials for the efficient operation of roadway networks. It has been required that these systems should prove their effectiveness in terms of travel time reliability. Therefore, this study aims to develop a new concept of a decision support system integrating variable speed limits, queue warning, and ramp metering on the basis of travel time reliability of freeways and arterials.Regarding the data preparation, in addition to collecting multiple data sources such as traffic data, crash data and so on, the types of traffic data sources that can be applied for the analysis of travel time reliability were investigated. Although there are many kinds of real-time traffic data from third-party traffic data providers, it was confirmed that these data cannot represent true travel time reliability through the comparative analysis of measures of travel time reliability. Related to weather data, it was proven that nationwide land-based weather stations could be applicable.Since travel time reliability can be measured by using long-term periods for more than six months, it is necessary to develop models to estimate travel time reliability through real-time traffic data and event-related data. Among various matrix to measure travel time reliability, the standard deviation of travel time rate [minute/mile] representing travel time variability was chosen because it can represent travel time variability of both link and network level. Several models were developed to estimate the standard deviation of travel time rate through average travel time rate, the number of lanes, speed limits, and the amount of rainfall.Finally, a DSS using a model predictive control method to integrate multiple traffic control measures was developed and evaluated. As a representative model predictive control, METANET model was chosen, which can include variable speed limit, queue warning, and ramp metering, separately or combined. The developed DSS identified a proper response plan by comparing travel time reliability among multiple combinations of current and new response values of strategies. In the end, it was found that the DSS provided the reduction of travel time and improvement of its reliability for travelers through the recommended response plans.
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Date Issued: 2019
Identifier: CFE0007615, ucf:52542
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007615

Title: MEASURING AND IMPROVING INTERNET VIDEO QUALITY OF EXPERIENCE.
Creator: Iyengar, Mukundan, Chatterjee, Mainak, University of Central Florida
Abstract / Description: Streaming multimedia content over the IP-network is poised to be the dominant Internet traffic for the coming decade, predicted to account for more than 91% of all consumer traffic in the coming years. Streaming multimedia content ranges from Internet television (IPTV), video on demand (VoD), peer-to-peer streaming, and 3D television over IP to name a few. Widespread acceptance, growth, and subscriber retention are contingent upon network providers assuring superior Quality of Experience (QoE...
Show moreStreaming multimedia content over the IP-network is poised to be the dominant Internet traffic for the coming decade, predicted to account for more than 91% of all consumer traffic in the coming years. Streaming multimedia content ranges from Internet television (IPTV), video on demand (VoD), peer-to-peer streaming, and 3D television over IP to name a few. Widespread acceptance, growth, and subscriber retention are contingent upon network providers assuring superior Quality of Experience (QoE) on top of todays Internet. This work presents the first empirical understanding of Internet's video-QoE capabilities, and tools and protocols to efficiently infer and improve them. To infer video-QoE at arbitrary nodes in the Internet, we design and implement MintMOS: a lightweight, real-time, no-reference framework for capturing perceptual quality. We demonstrate that MintMOS's projections closely match with subjective surveys in accessing perceptual quality. We use MintMOS to characterize Internet video-QoE both at the link level and end-to-end path level. As an input to our study, we use extensive measurements from a large number of Internet paths obtained from various measurement overlays deployed using PlanetLab. Link level degradations of intra-- and inter--ISP Internet links are studied to create an empirical understanding of their shortcomings and ways to overcome them. Our studies show that intra--ISP links are often poorly engineered compared to peering links, and that degradations are induced due to transient network load imbalance within an ISP. Initial results also indicate that overlay networks could be a promising way to avoid such ISPs in times of degradations. A large number of end-to-end Internet paths are probed and we measure delay, jitter, and loss rates. The measurement data is analyzed offline to identify ways to enable a source to select alternate paths in an overlay network to improve video-QoE, without the need for background monitoring or apriori knowledge of path characteristics. We establish that for any unstructured overlay of N nodes, it is sufficient to reroute key frames using a random subset of k nodes in the overlay, where k is bounded by O(lnN). We analyze various properties of such random subsets to derive simple, scalable, and an efficient path selection strategy that results in a k-fold increase in path options for any source-destination pair; options that consistently outperform Internet path selection. Finally, we design a prototype called source initiated frame restoration (SIFR) that employs random subsets to derive alternate paths and demonstrate its effectiveness in improving Internet video-QoE.
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Date Issued: 2011
Identifier: CFE0004012, ucf:49168
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004012

Title: The Impact of Timed Versus Untimed Standardized Tests On Reading Scores Of Third Grade Students in Title I Schools.
Creator: Haniff, Ruthie, Stewart, Martha, Holt, Larry, Platt, Jennifer, Clark, Margaret, Purmensky, Kerry, University of Central Florida
Abstract / Description: The purpose of this study was to investigate the extent to which the performance of Title I third grade students in a central Florida School District differed on tests dministered under timed and untimed conditions. Further examined was the literature on reasons for the achievement gap which centered around seven different themes: (a) standardized testing, (b) achievement gap data and identified factors (c) deficit theory, (d) cultural mismatch theory, (e) extended time accommodations, (f)...
Show moreThe purpose of this study was to investigate the extent to which the performance of Title I third grade students in a central Florida School District differed on tests dministered under timed and untimed conditions. Further examined was the literature on reasons for the achievement gap which centered around seven different themes: (a) standardized testing, (b) achievement gap data and identified factors (c) deficit theory, (d) cultural mismatch theory, (e) extended time accommodations, (f) test anxiety and stress, and (g) timed versus untimed tests.Six Title I schools participated in this study by assigning 194 students to take the 2006 Released FCAT Reading Test under either timed or untimed conditions. Although there were no interactions between the covariates and testing conditions, those who were in the free or reduced lunch program or were in exceptional education programs had lower FCAT scores than those who were not. However, when school was included as a moderator, there was a statistically significant interaction between testing conditions and schools on FCAT scores indicating that the relationship between testing conditions and FCAT scores varied for each individual school.A factorial ANCOVA was conducted, and it was found that the mean differences between students who took the timed and untimed 2006 FCAT Reading Test varied from school to school after accounting for the covariates. For two schools, those students who took the untimed tests scored higher than those who took the timed tests. In contrast, those students who took the untimed tests scored lower than those students who took thetimed test for one of the schools. There was no statistically significant difference for three of the schools.A factorial MANCOVA was used to compare reading performance on the 2006 Reading FCAT between the timed and untimed groups on domain specific tests. The relationship between testing condition and FCAT scores for each domain specific test varied depending on the individual school. Therefore, it could not be concluded from these analyses that testing conditions would consistently result in increases or decreases of student performance on standardized domain specific tests.
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Date Issued: 2012
Identifier: CFE0004381, ucf:49407
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004381

Title: DELAY MODELING AND LONG-RANGE PREDICTIVE CONTROL OF CZOCHRALSKI GROWTH PROCESS.
Creator: Shah, Dhaval, Klemenz, Christine, University of Central Florida
Abstract / Description: This work presents the Czochralski growth dynamics as time-varying delay based model, applied to the growth of La3Ga5.5Ta0.5O14 (LGT) piezoelectric crystals. The growth of high-quality large-diameter oxides by Czochralski technique requires the theoretical understanding and optimization of all relevant process parameters, growth conditions, and melts chemistry. Presently, proportional-integral- derivative (PID) type controllers are widely accepted for constant-diameter crystal growth by...
Show moreThis work presents the Czochralski growth dynamics as time-varying delay based model, applied to the growth of La3Ga5.5Ta0.5O14 (LGT) piezoelectric crystals. The growth of high-quality large-diameter oxides by Czochralski technique requires the theoretical understanding and optimization of all relevant process parameters, growth conditions, and melts chemistry. Presently, proportional-integral- derivative (PID) type controllers are widely accepted for constant-diameter crystal growth by Czochralski. Such control systems, however, do not account for aspects such as the transportation delay of the heat from crucible wall to the crystal solidification front, heat radiated from the crucible wall above the melt surface, and varying melt level. During crystal growth, these time delays play a dominant role, and pose a significant challenge to the control design. In this study, a time varying linear delay model was applied to the identification of nonlinearities of the growth dynamics. Initial results reveled the benefits of this model with actual growth results. These results were used to develop a long-range model predictive control system design. Two different control techniques using long range prediction are studied for the comparative study. Development and testing of the new control system on real time growth system are discussed in detail. The results are promising and suggest future work in this direction. Other discussion about the problems during the crystal growth, optimization of crystal growth parameters are also studied along with the control system design.
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Date Issued: 2009
Identifier: CFE0002581, ucf:48250
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002581

Title: THE RELEVANCE OF TIME-TO-DIGITAL CONVERTERS TO SMALL PLATFORM DIRECTION FINDING SYSTEMS.
Creator: Nelson, Paul, Gong, Xun, University of Central Florida
Abstract / Description: This thesis explores a Time-Difference-of-Arrival (TDOA) approach to radio direction finding, utilizing picosecond-resolution Time-to-Digital Converters (TDCs). By measuring the relative time of arrival of a pulsed RF signal impinging on an antenna array, direction of arrival (DOA) can be ascertained. This technology enables versatile DOA calculation on platforms only several meters in length, and offers various size, weight, power, and cost advantages when compared to present DF technologies...
Show moreThis thesis explores a Time-Difference-of-Arrival (TDOA) approach to radio direction finding, utilizing picosecond-resolution Time-to-Digital Converters (TDCs). By measuring the relative time of arrival of a pulsed RF signal impinging on an antenna array, direction of arrival (DOA) can be ascertained. This technology enables versatile DOA calculation on platforms only several meters in length, and offers various size, weight, power, and cost advantages when compared to present DF technologies. A short baseline S-band TDOA DF system utilizing TDCs is designed, fabricated, and tested in a laboratory environment. This research suggests that such a DF system based on TDCs provides sufficient accuracy and precision to resolve Angle-of-Arrival (AOA) within several degrees.
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Date Issued: 2010
Identifier: CFE0003115, ucf:48649
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003115

Title: Combustion of 1,3-Butadiene behind Reflected Shocks.
Creator: Lopez, Joseph, Vasu Sumathi, Subith, Orlovskaya, Nina, Kassab, Alain, University of Central Florida
Abstract / Description: The chemical kinetics of 1,3-butadiene (1,3-C4H6) are important because 1,3-butadiene is a major intermediate during the combustion of real fuels. However, there is only limited information on the chemical kinetics of 1,3-butadiene combustion, which has applications in several combustion schemes that are currently being developed, including spark-assisted homogeneous charge compression ignition and fuel reformate exhaust gas recirculation.In the present work, the ignition delay times of 1,3...
Show moreThe chemical kinetics of 1,3-butadiene (1,3-C4H6) are important because 1,3-butadiene is a major intermediate during the combustion of real fuels. However, there is only limited information on the chemical kinetics of 1,3-butadiene combustion, which has applications in several combustion schemes that are currently being developed, including spark-assisted homogeneous charge compression ignition and fuel reformate exhaust gas recirculation.In the present work, the ignition delay times of 1,3-butadiene mixtures has been investigated using pressure data. Oxidation of 1,3-butadiene/oxygen mixtures diluted in argon or nitrogen at equivalence ratios (?) of 0.3 behind reflected shock waves has been studied at temperatures ranging from 1100 to 1300K and at pressures ranging from 1 to 2atm. Reaction progress was monitored by recording concentration time-histories of 1,3-butadiene and OH* radical at a location 2cm from the end wall of a 13.4m long shock tube with an inner diameter of 14cm. 1,3-Butadiene concentration time-histories were measured by absorption spectroscopy at 10.5?m from the P14 line of a tunable CO2 gas laser. OH* production was measured by recording emission around 306.5nm with a pre-amplified gallium phosphide detector and a bandpass filter. Ignition delay times were also determined from the OH* concentration time-histories. The measured concentration time-histories and ignition delay times were compared with two chemical kinetics models. The measured time-histories and ignition delay times provide targets for the refinement of chemical kinetic models at the studied conditions.
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Date Issued: 2017
Identifier: CFE0006618, ucf:51276
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006618

Title: Optimization of Molecular Beacon-Based Multicomponent Probes for Analysis of Nucleic Acids.
Creator: Stancescu, Maria, Kolpashchikov, Dmitry, Clausen, Christian, Koculi, Eda, Balaeff, Alexander, Shuler, Michael, University of Central Florida
Abstract / Description: Detection of single nucleotide substitutions (SNS) in DNA and RNA has a growing importance in biology and medicine. One traditional approach for recognition of SNS takes advantage of hybridization probes that bind target nucleic acids followed by measuring ?Tm, the difference in melting temperatures of matched and mismatched hybrids. The approach enables SNS differentiation at elevated temperatures (usually 40-65oC) often only in a narrow range of (
Show moreDetection of single nucleotide substitutions (SNS) in DNA and RNA has a growing importance in biology and medicine. One traditional approach for recognition of SNS takes advantage of hybridization probes that bind target nucleic acids followed by measuring ?Tm, the difference in melting temperatures of matched and mismatched hybrids. The approach enables SNS differentiation at elevated temperatures (usually 40-65oC) often only in a narrow range of (<)10oC and requires high-resolution melting devices. Here we demonstrate that a specially designed DNA probe (X sensor) can broaden ?Tm from ~10oC to ~16oC and distinguish SNS in the interval of ~5-40oC. Therefore, there is no need for heating or measuring Tm for accurate SNS differentiation. Our data indicate that this wide differentiation range is in part due to the non-equilibrium hybridization conditions. Further we explored the idea that it is possible to improve the performance of an X sensor operable in close to equilibrium conditions by shifting its operability to non-equilibrium conditions. One way to achieve this is to introduce as many as possible structured ligands in analyte's dissociated state. Here we show that by introducing the maximum possible conformational constraints in X probe it is possible to shift its operation to non-equilibrium conditions and to improve its selectivity at temperatures (<)15oC. Thus, this work points towards a new strategy for the design of highly selective hybridization sensors which operate in non-equilibrium conditions at close to room temperature. The X sensors could be utilized in qPCR, microarrays, as well as RNA analysis in living cells and for ambient temperature point-of-care diagnostics. In the last part of this work, X sensors were used in real time detection of PCR products. The sensors were optimized to operate in PCR buffer with optimal Mg2+ concentration. They were able to detect the target amplicon together with nonspecific products. The results presented here suggest that X sensors might be adopted for real time PCR format.
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Date Issued: 2015
Identifier: CFE0006009, ucf:51006
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006009

Title: High Temperature Shock Tube Ignition Studies of CO2 Diluted Mixtures.
Creator: Pryor, Owen, Vasu Sumathi, Subith, Kapat, Jayanta, Kassab, Alain, University of Central Florida
Abstract / Description: Energy demand is expected to grow by 20% over the next 10 years. In order to account for this increase in energy consumption new and novel combustion techniques are required to mitigate the effects of pollution and fossil fuel dependency. Oxy-fuel combustion in supercritical carbon dioxide (sCO2) cycles can increase plant efficiencies up to 52% and reduce pollutants such as NOX and CO2 by 99%. Supercritical engine cycles have demonstrated electricity costs of $121/MWh, which is competitive in...
Show moreEnergy demand is expected to grow by 20% over the next 10 years. In order to account for this increase in energy consumption new and novel combustion techniques are required to mitigate the effects of pollution and fossil fuel dependency. Oxy-fuel combustion in supercritical carbon dioxide (sCO2) cycles can increase plant efficiencies up to 52% and reduce pollutants such as NOX and CO2 by 99%. Supercritical engine cycles have demonstrated electricity costs of $121/MWh, which is competitive in comparison to conventional coal ($95.60/MWh) and natural gas power plants ($128.4/MWe). This increase in efficiency is mainly driven by the near-liquid density of the working fluid (sCO2), in the super critical regime, before entering the turbine for energy extraction of the high pressure and high density sCO2 gas. In addition, supercritical CO2 engine cycles produce near-zero air emissions since CO2, a product of combustion, is the working fluid of the system which can be regenerated to the combustor. The predictive accuracy and lack of combustion models in highly CO2 diluted mixtures and at high pressures is one the major limitations to achieving optimum design of super critical engine combustors. Also, most natural gas mechanisms and validation experiments have been conducted at low pressures (typically less than 40 atm) and not in CO2 diluted environment. Thus experimental data is important for the development of modern combustion systems from work focusing on supercritical carbon dioxide cycles to rotational detonation engines. This thesis presents the design of the shock tube and two optical diagnostic techniques for measuring ignition delay times and species time histories using a shock tube in CO2 diluted mixtures.Experimental data for ignition delay times and species time-histories (CH4) were obtained in mixtures diluted with CO2. Experiments were performed behind reflected shockwaves from temperatures of 1200 to 2000 K for pressures ranging from 1 to 11 atm. Ignition times were obtained from emission and laser absorption measurements. Current experimental data were compared with the predictions of detailed chemical kinetic models (available from literature) that will allow for accurate design and modeling of combustion systems.
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Date Issued: 2016
Identifier: CFE0006165, ucf:51141
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006165

Title: Interactive Amusement Park Queues: Examining the Indirect Effect of Task Work Load on Guests' Perception of Wait Duration Through Task Immersion.
Creator: Ledbetter, Jonathan, Smither, Janan, Hancock, Peter, Joseph, Dana, Sims, Valerie, Allen, Robert, University of Central Florida
Abstract / Description: With the increasing attendance across amusement and theme parks worldwide, it is not surprising that minimizing the impact of large crowds and long attraction waits on the guests' experience has received much focus by park operators in recent years. Although effective in the short term, attempting to eliminate or reduce wait times by simply increasing capacity cannot be sustained long term. A recent trend in amusement park design is to theme the queue with interactive elements to engage...
Show moreWith the increasing attendance across amusement and theme parks worldwide, it is not surprising that minimizing the impact of large crowds and long attraction waits on the guests' experience has received much focus by park operators in recent years. Although effective in the short term, attempting to eliminate or reduce wait times by simply increasing capacity cannot be sustained long term. A recent trend in amusement park design is to theme the queue with interactive elements to engage guests and occupy their wait time with the intent of making the wait queue part of the attraction itself. Much of the research on the topic of waiting in line focuses on improving the customers' experience while waiting by altering the wait queue. Very little research to date empirically tests the impact that queue characteristics have on a customers' perceived wait duration with the research pool void of any applications to an interactive amusement park queue. This dissertation study tested five hypotheses to determine how playing an interactive math skills game while waiting to ride a virtual roller coaster affected the participants' perceived wait duration. The first hypothesis tested if the participants' perceived wait time decreased as the mental workload of the game increased. The results did not find that this effect of mental workload on perception of time was significant. The second hypothesis tested whether participants who experience higher levels of game immersion estimate perceive wait time to be lower. The results indicated that this effect of game immersion on perceived wait time was significant. The third hypothesis tested whether participants' experience higher levels of game immersion when the perceived mental workload of the math skills game was higher. This effect of mental workload on immersion was found to be significant.Hypothesis 4 tested whether the participants' perceived wait time was indirectly effected by the mental workload of the math skills through immersion. This indirect effect was found to be significant and the results support complete mediation by immersion because the direct effect was not significant with the indirect effect in the model. Hypothesis tested whether the mediated effect of mental workload on time perception via game immersion was moderated by participants' levels of sensation seeking and extraversion. Individual differences of extraversion and sensation seeking were not found to moderate the indirect effect.This study demonstrates that research in the area of time perception can be applied to amusement and theme park queue design. Furthermore, it shows the importance of providing guests with an immersive queue experience to positively impact their perception of wait time, the number one complaint of many amusement and theme park visitors. Future research in this field should examine the individual elements of the queue environment to determine the optimal design to increase the level of immersion for park guests.
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Date Issued: 2016
Identifier: CFE0006135, ucf:51183
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006135

response time (4)	+ -
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United States (3)	+ -
ignition delay time (3)	+ -
liquid crystal (3)	+ -
shock tube (3)	+ -
time series (3)	+ -
time series analysis (3)	+ -
Combustion (2)	+ -
Content Analysis (2)	+ -
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