View All Items
(1 - 20 of 39)
Pages
- 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.
Show less - Date Issued
- 2006
- Identifier
- CFE0001049, ucf:46808
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001049
- Title
- PREDICTIVE CONTROL FOR DYNAMIC SYSTEMS TO TRACK UNKNOWN INPUT IN THE PRESENCE OF TIME DELAY.
- Creator
-
Li, Yulan, Qu, Zhihua, University of Central Florida
- Abstract / Description
-
This study investigated a tracking system to trace unknown signal in the presence oftime delay. A predictive control method is proposed in order to compensate the time delay. Root locus method is applied when designing the controller, parameter setting is carried out through error and trail technique in w-plane. State space equation is derived for the system, with special state chose of tracking error. To analyze the asymptotic stability of the proposed predictive control system, the Lyapunov...
Show moreThis study investigated a tracking system to trace unknown signal in the presence oftime delay. A predictive control method is proposed in order to compensate the time delay. Root locus method is applied when designing the controller, parameter setting is carried out through error and trail technique in w-plane. State space equation is derived for the system, with special state chose of tracking error. To analyze the asymptotic stability of the proposed predictive control system, the Lyapunov function is constructed. It is shown that the designed system is asymptotically stable when input signal is rather low frequency signal. In order to illustrate the system performance, simulations are done based on the data profile technique. Signal profiles including acceleration pro le, velocity pro le, and trajectory profile are listed. Based on these profiles, simulations can be carried out and results can be taken as a good estimation for practical performance of the designed predictive control system. Signal noise is quite a common phenomenon in practical control systems. Under the situation that the input signal is with measurement noise, low pass filter is designed to filter out the noise and keep the low frequency input signal. Two typical kinds of noise are specified, i.e Gaussian noise and Pink noise. Simulations results are displayed to show that the proposed predictive control with low-pass filter design can achieve better performance in the case of both kinds of noise.
Show less - Date Issued
- 2005
- Identifier
- CFE0000819, ucf:46688
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000819
- Title
- TIME ON FLORIDA'S DEATH ROW: A THEORY OF "BENIGN NEGLECT".
- Creator
-
Willis, Angela, Bohm, Robert, University of Central Florida
- Abstract / Description
-
This thesis attempts to identify and explain what influences the length of time an inmate spends on Florida's death row. A systematic random sample of 33 Florida death row inmates was drawn from the Florida Department of Corrections death row roster and the Florida Commission on Capital Cases inmate roster. Documented for each death row inmate was how long he spent on Florida's death row navigating the various stages and steps in Florida's post-conviction capital punishment...
Show moreThis thesis attempts to identify and explain what influences the length of time an inmate spends on Florida's death row. A systematic random sample of 33 Florida death row inmates was drawn from the Florida Department of Corrections death row roster and the Florida Commission on Capital Cases inmate roster. Documented for each death row inmate was how long he spent on Florida's death row navigating the various stages and steps in Florida's post-conviction capital punishment process. The data show that petitions to the state trial courts and appeals to the Florida Supreme Court take the longest time in Florida's post-conviction capital punishment process. It also shows a considerable amount of "dead time," which refers to any additional time that an inmate spends on death row with no legal actions pending. A theory of "benign neglect" is proposed as the most likely explanation for the excessive delays.
Show less - Date Issued
- 2008
- Identifier
- CFE0002328, ucf:47775
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002328
- Title
- Barriers to timely administration of thrombolytics in acute ischemic stroke patients.
- Creator
-
Joseph, Elizabeth, Talbert, Steven, Chase, Susan, Ullah, Saif, University of Central Florida
- Abstract / Description
-
Stroke is a leading cause of long term disability in the United States. The therapeutic benefits of intravenous thrombolytics is time dependent in an acute ischemic stroke patient and is an important determinant of 90 day and one year functional outcomes. This study investigated areas in the stroke alert process of a community based primary stroke care center that resulted in the delay of administration of thrombolytics within 60 minutes of an acute ischemic stroke patient's arrival to the...
Show moreStroke is a leading cause of long term disability in the United States. The therapeutic benefits of intravenous thrombolytics is time dependent in an acute ischemic stroke patient and is an important determinant of 90 day and one year functional outcomes. This study investigated areas in the stroke alert process of a community based primary stroke care center that resulted in the delay of administration of thrombolytics within 60 minutes of an acute ischemic stroke patient's arrival to the emergency room. A retrospective descriptive design was utilized and chart reviews were done on 40 patients that received thrombolytics in the emergency room. Patient characteristics and time variables associated with the various steps in the stroke alert process were extracted. Findings showed that only 7.5% of the patients received thrombolytics within the recommended 60 minutes, with the longest time interval associated with time from arrival to the emergency room to time of evaluation by teleneurologist. There were no significant differences in the characteristics of patients who received thrombolytics within 60 minutes and those patients that received thrombolytics after 60 minutes. Recommendations were made for changes in organizational and practice strategies to improve timely administration, and for future research involving the effects of quality improvement initiatives.
Show less - Date Issued
- 2012
- Identifier
- CFE0004390, ucf:49406
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004390
- Title
- DEVELOPMENT OF AN ARTIFICIAL NEURAL NETWORKS MODEL TO ESTIMATE DELAY USING TOLL PLAZA TRANSACTION DATA.
- Creator
-
Muppidi, Aparna, Al-Deek, Haitham, University of Central Florida
- Abstract / Description
-
In spite of the most up-to-date investigation of the relevant techniques to analyze the traffic characteristics and traffic operations at a toll plaza, there has not been any note worthy explorations evaluating delay from toll transaction data and using Artificial Neural Networks (ANN) at a toll plaza. This thesis lays an emphasis on the application of ANN techniques to estimate the total vehicular delay according to the lane type at a toll plaza. This is done to avoid the laborious task of...
Show moreIn spite of the most up-to-date investigation of the relevant techniques to analyze the traffic characteristics and traffic operations at a toll plaza, there has not been any note worthy explorations evaluating delay from toll transaction data and using Artificial Neural Networks (ANN) at a toll plaza. This thesis lays an emphasis on the application of ANN techniques to estimate the total vehicular delay according to the lane type at a toll plaza. This is done to avoid the laborious task of extracting data from the video recordings at a toll plaza. Based on the lane type a general methodology was developed to estimate the total vehicular delay at a toll plaza using ANN. Since there is zero delay in an Electronic Toll Collection (ETC) lane, ANN models were developed for estimating the total vehicular delay in a manual lane and automatic coin machine lane. Therefore, there are two ANN models developed in this thesis. These two ANN models were trained with three hours of data and validated with one hour of data from AM and PM peak data. The two ANN models were built with the dependent and independent variables. The dependent variables in the two models were the total vehicular delay for both the manual and automatic coin machine lane. The independent variables are those, which influence delay. A correlation analysis was performed to see if there exists any strong relationship between the dependent (outputs) and independent variables (inputs). These inputs and outputs are fed into the ANN models. The MATLABTB code was written to run the two ANN models. ANN predictions were good at estimating delay in manual lane, and delay in automatic coin machine lane.
Show less - Date Issued
- 2005
- Identifier
- CFE0000334, ucf:46298
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000334
- Title
- CHARACTERIZATION OF A HYDROGEN-BASED SYNTHETIC FUEL IN A SHOCK TUBE.
- Creator
-
Flaherty, Troy, Kassab, Alain, University of Central Florida
- Abstract / Description
-
Shock-tube experiments were performed with syngas mixtures near atmospheric pressure with varying equivalence ratios behind reflected shock waves. Pressure and hydroxyl radical (OH*) emission traces were recorded and used to calculate ignition delay time for a single mixture at equivalence ratios of 0.4, 0.7, 1.0, and 2.0 over a range of temperatures from 913 – 1803 K. The syngas mixture was tested at full concentration as well as with 98% dilution in Argon. The full concentration...
Show moreShock-tube experiments were performed with syngas mixtures near atmospheric pressure with varying equivalence ratios behind reflected shock waves. Pressure and hydroxyl radical (OH*) emission traces were recorded and used to calculate ignition delay time for a single mixture at equivalence ratios of 0.4, 0.7, 1.0, and 2.0 over a range of temperatures from 913 – 1803 K. The syngas mixture was tested at full concentration as well as with 98% dilution in Argon. The full concentration mixtures were used to compare ignition delay time measurements with the theoretical calculations obtained through the use of chemical kinetics modeling using the Davis et al. mechanism. The dilute mixtures were used to study the OH* emission profiles compared to those of the kinetics model. The model was in poor agreement with the experimental data especially at lower temperatures with an ignition delay difference of more than an order of magnitude. These ignition delay time data supplement the few existing data and are in relative agreement. The species profile comparison of OH* compared to the model also showed poor agreement, with the worst agreement at the highest temperatures. While the disagreements with ignition delay time and profile comparisons cannot be explained at this time, the data presented support other findings. The data provide additional information towards understanding this disagreement relative to syngas mixtures despite the relatively well known kinetics of the primary constituents Hydrogen and Carbon Monoxide.
Show less - Date Issued
- 2009
- Identifier
- CFE0002552, ucf:47657
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002552
- Title
- REPRODUCTIVE DELAY IN THE FEMALE CAPE GROUND SQUIRREL (XERUS INAURIS).
- Creator
-
Pettitt, Beth, Waterman, Jane, University of Central Florida
- Abstract / Description
-
The Cape ground squirrel, Xerus inauris, is a highly social cooperative breeder that forms groups containing multiple breeding females. While the distribution of reproduction among group members is fairly even (i.e. exhibits low reproductive skew), previous studies of Cape ground squirrels suggest the reproductive development of sub-adult females is inhibited by the presence of adult breeding female group mates. As reproductive delay is known to be influenced by a number of different...
Show moreThe Cape ground squirrel, Xerus inauris, is a highly social cooperative breeder that forms groups containing multiple breeding females. While the distribution of reproduction among group members is fairly even (i.e. exhibits low reproductive skew), previous studies of Cape ground squirrels suggest the reproductive development of sub-adult females is inhibited by the presence of adult breeding female group mates. As reproductive delay is known to be influenced by a number of different parameters, my goal was to determine if other factors affected the timing of sexual maturity, and if so, which factors are the most influential. In this study, I simultaneously test the relative power of seven different social and environmental parameters at explaining the variation in the female age of sexual maturity in two populations of Cape ground squirrels. Field work was conducted at two study sites in southern Africa, where trapping, behavioral and hormonal data were collected to determine the timing of reproductive development. Hormonal data was analyzed through the use of steroid enzyme immunoassay analysis to quantify the concentration of gonadal hormone in fecal samples which indicate the onset of sexual maturity. Prior to the start of the field season, I conducted an initial experiment to determine the best alternative form of fecal storage if freezing was unavailable. I found that drying feces provides a more reliable method for long-term preservation of fecal steroid concentrations when compared to storing fecal samples in alcohol. Data associated with each of the seven parameters was analyzed using model selection to simultaneously measure the ability of different combinations of parameters to explain the observed variation in female age of sexual maturity. I found that an increase in the number of adult breeding female group mates and related adult male group mates resulted in a substantial inhibition of female reproductive maturity. I concluded that a female Cape ground squirrel's age of sexual maturity is principally a result of the interaction between adult breeding females' capacity for reproductive suppression and sub-adults' ability to maximize lifetime reproductive success while minimizing inbreeding. The overall reproductive dynamics of each social group results from the tug-of-war between the adult and sub-adult female group mates to control breeding within the group, with minimal direct influence on sexual maturity by environmental factors.
Show less - Date Issued
- 2006
- Identifier
- CFE0001021, ucf:46788
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001021
- Title
- SHOCK-TUBE INVESTIGATION OF IGNITION DELAY TIMES OF BLENDS OF METHANE AND ETHANE WITH OXYGEN.
- Creator
-
Walker, Brian, Petersen, Eric, University of Central Florida
- Abstract / Description
-
The combustion behavior of methane and ethane is important to the study of natural gas and other alternative fuels that are comprised primarily of these two basic hydrocarbons. Understanding the transition from methane-dominated ignition kinetics to ethane-dominated kinetics for increasing levels of ethane is also of fundamental interest toward the understanding of hydrocarbon chemical kinetics. Much research has been conducted on the two fuels individually, but experimental data of the...
Show moreThe combustion behavior of methane and ethane is important to the study of natural gas and other alternative fuels that are comprised primarily of these two basic hydrocarbons. Understanding the transition from methane-dominated ignition kinetics to ethane-dominated kinetics for increasing levels of ethane is also of fundamental interest toward the understanding of hydrocarbon chemical kinetics. Much research has been conducted on the two fuels individually, but experimental data of the combustion of blends of methane and ethane is limited to ratios that recreate typical natural gas compositions (up to ~20% ethane molar concentration). The goal of this study was to provide a comprehensive data set of ignition delay times of the combustion of blends of methane and ethane at near atmospheric pressure. A group of ten diluted CH4/C2H6/O2/Ar mixtures of varying concentrations, fuel blend ratios, and equivalence ratios (0.5 and 1.0) were studied over the temperature range 1223 to 2248 K and over the pressure range 0.65 to 1.42 atm using a new shock tube at the University of Central Florida Gas Dynamics Laboratory. Mixtures were diluted with either 75 or 98% argon by volume. The fuel blend ratio was varied between 100% CH4 and 100% C2H6. Reaction progress was monitored by observing chemiluminescence emission from CH* at 431 nm and the pressure. Experimental data were compared against three detailed chemical kinetics mechanisms. Model predictions of CH* emission profiles and derived ignition delay times were plotted against the experimental data. The models agree well with the experimental data for mixtures with low levels of ethane, up to 25% molar concentration, but show increasing error as the relative ethane fuel concentration increases. The predictions of the separate models also diverge from each other with increasing relative ethane fuel concentration. Therefore, the data set obtained from the present work provides valuable information for the future improvement of chemical kinetics models for ethane combustion.
Show less - Date Issued
- 2007
- Identifier
- CFE0001956, ucf:47442
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001956
- Title
- THE EFFECT OF PRE-K EARLY INTERVENTION DURATION ON ACADEMIC ACHIEVEMENT AND SOCIALIZATION OPPORTUNITIES OF 3RD GRADE STUDENTS WHO WERE ELIGIBLE FOR SPECIAL EDUCATION SERVICES AT AGES 3 TO 5: AN EXPLORATORY STUDY OF CHILDREN WITH DEVELOPMENTAL DELAYS.
- Creator
-
Lin, Mike Chang-Hui, Wienke, Wilfred, University of Central Florida
- Abstract / Description
-
The study focuses on young children with developmental delays (DD) in a large school district and explores the effects of Pre-Kindergarten Exceptional Student Education (Pre-K ESE) duration on 136 students' 3rd grade academic achievement and socialization opportunities. This study specifically examines the 2003 statewide assessment (i.e. Florida Comprehensive Assessment Test, FCAT) results of children with DD and their 3rd grade special education status. The literature review showed that...
Show moreThe study focuses on young children with developmental delays (DD) in a large school district and explores the effects of Pre-Kindergarten Exceptional Student Education (Pre-K ESE) duration on 136 students' 3rd grade academic achievement and socialization opportunities. This study specifically examines the 2003 statewide assessment (i.e. Florida Comprehensive Assessment Test, FCAT) results of children with DD and their 3rd grade special education status. The literature review showed that providing early intervention services for young children ages 3 through 5 with special needs in the public school system has become the movement of both the federal and state educational policies. However, the empirical studies regarding the effects of Pre-K early intervention programs provided within the public school system are few. A multivariate analysis of covariance (MANCOVA) was conducted to examine the effect of the Pre-K duration (1 year vs. 2 years) on students' 3rd grade performance as measured by FCAT Reading scores, FCAT Math scores, and socialization opportunities (i.e. weekly Non-ESE minutes) while controlling for students' socioeconomic status (i.e. free/reduced price lunch status) and gender. Moreover, a paired sample t test was conducted to examine the difference of the Matrix of Services scores between Pre-K and 3rd grade evaluations. The results of this study provide an insightful picture of Florida Pre-K intervention duration on the performance of children with special needs in public schools.
Show less - Date Issued
- 2005
- Identifier
- CFE0000672, ucf:46537
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000672
- Title
- DYNAMIC SHARED STATE MAINTENANCE IN DISTRIBUTED VIRTUAL ENVIRONMENTS.
- Creator
-
Hamza-Lup, Felix George, Hughes, Charles, University of Central Florida
- Abstract / Description
-
Advances in computer networks and rendering systems facilitate the creation of distributed collaborative environments in which the distribution of information at remote locations allows efficient communication. Particularly challenging are distributed interactive Virtual Environments (VE) that allow knowledge sharing through 3D information. In a distributed interactive VE the dynamic shared state represents the changing information that multiple machines must maintain about the shared virtual...
Show moreAdvances in computer networks and rendering systems facilitate the creation of distributed collaborative environments in which the distribution of information at remote locations allows efficient communication. Particularly challenging are distributed interactive Virtual Environments (VE) that allow knowledge sharing through 3D information. In a distributed interactive VE the dynamic shared state represents the changing information that multiple machines must maintain about the shared virtual components. One of the challenges in such environments is maintaining a consistent view of the dynamic shared state in the presence of inevitable network latency and jitter. A consistent view of the shared scene will significantly increase the sense of presence among participants and facilitate their interactive collaboration. The purpose of this work is to address the problem of latency in distributed interactive VE and to develop a conceptual model for consistency maintenance in these environments based on the participant interaction model.A review of the literature illustrates that the techniques for consistency maintenance in distributed Virtual Reality (VR) environments can be roughly grouped into three categories: centralized information management, prediction through dead reckoning algorithms, and frequent state regeneration. Additional resource management methods can be applied across these techniques for shared state consistency improvement. Some of these techniques are related to the systems infrastructure, others are related to the human nature of the participants (e.g., human perceptual limitations, area of interest management, and visual and temporal perception).An area that needs to be explored is the relationship between the dynamic shared state and the interaction with the virtual entities present in the shared scene. Mixed Reality (MR) and VR environments must bring the human participant interaction into the loop through a wide range of electronic motion sensors, and haptic devices. Part of the work presented here defines a novel criterion for categorization of distributed interactive VE and introduces, as well as analyzes, an adaptive synchronization algorithm for consistency maintenance in such environments. As part of the work, a distributed interactive Augmented Reality (AR) testbed and the algorithm implementation details are presented. Currently the testbed is part of several research efforts at the Optical Diagnostics and Applications Laboratory including 3D visualization applications using custom built head-mounted displays (HMDs) with optical motion tracking and a medical training prototype for endotracheal intubation and medical prognostics. An objective method using quaternion calculus is applied for the algorithm assessment. In spite of significant network latency, results show that the dynamic shared state can be maintained consistent at multiple remotely located sites. In further consideration of the latency problems and in the light of the current trends in interactive distributed VE applications, we propose a hybrid distributed system architecture for sensor-based distributed VE that has the potential to improve the system real-time behavior and scalability.
Show less - Date Issued
- 2004
- Identifier
- CFE0000096, ucf:46152
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000096
- 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.
Show less - Date Issued
- 2014
- Identifier
- CFH0004635, ucf:45253
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004635
- Title
- Enriching Students With Developmental Delays in an Early Childhood Classroom Using iPads With Mathematics Applications.
- Creator
-
Powell, Selma, Dieker, Lisa, Little, Mary, Cross, Lee, Culp, Anne, University of Central Florida
- Abstract / Description
-
Laws and legislation related to early childhood and special education have shaped the field and impacted the need for early intervention services, but the outcomes of those services both academically and socially at the forefront. Children with developmental delays today are eligible for school services beginning at birth across the country, the new challenging is determining the impact of services on the social and academic outcomes. Many children with developmental delays are served in...
Show moreLaws and legislation related to early childhood and special education have shaped the field and impacted the need for early intervention services, but the outcomes of those services both academically and socially at the forefront. Children with developmental delays today are eligible for school services beginning at birth across the country, the new challenging is determining the impact of services on the social and academic outcomes. Many children with developmental delays are served in inclusive early intervention classrooms. A need for developmentally appropriate quality mathematics instruction exists to prepare students to meet the demands of a global economy; students must demonstrate mastery of core subjects, such as mathematics, along with skills in information and communication technology (Partnership for 21st Century Skills, 2009). To promote mathematics achievement technology should be infused in instruction. Data were collected through a variety of sources including: student records review, TEMA-3 test scores, researcher's observation field notes, transcripts from student exit interviews, teacher interviews pre and post data collection, and parent questionnaires. The data were analyzed using Atlas-ti and was triangulated from the various data sources. Inter-observer agreement was obtained for all the results. Researcher observations occurred for 19 days in a pre-kindergarten inclusive classroom. The data were analyzed to identify themes for the four individual cases as well as two overarching themes as it related to the investigation of utilizing handheld technology for mathematics instruction in an early childhood education setting.
Show less - Date Issued
- 2012
- Identifier
- CFE0004584, ucf:49197
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004584
- 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.
Show less - Date Issued
- 2009
- Identifier
- CFE0002581, ucf:48250
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002581
- 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.
Show less - Date Issued
- 2017
- Identifier
- CFE0006618, ucf:51276
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006618
- 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.
Show less - Date Issued
- 2016
- Identifier
- CFE0006165, ucf:51141
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006165
- Title
- SUPPORTING HISPANIC MOTHERS WITH PRESCHOOL CHILDREN WITH SPEECH AND/ OR LANGUAGE DELAYS VIA DIALOGIC READING AND COACHING WITHIN THE HOME.
- Creator
-
Dopson, Natalie, Cross, Lee, University of Central Florida
- Abstract / Description
-
Young children who are Hispanic, from low-income homes and have developmental delays are at a disadvantage for not having the basic early literacy foundation to become successful readers later in school (Ballantyne, Sanderman, D'Emilio, & McLaughlin, 2008; Hammer, Farkas, & Maczuga, 2010; Ezell & Justice 2005; McCardle, Scarborough, & Catts, 2001). These challenges can be addressed in several ways. Early intervention including parent education and collaboration along with shared book reading...
Show moreYoung children who are Hispanic, from low-income homes and have developmental delays are at a disadvantage for not having the basic early literacy foundation to become successful readers later in school (Ballantyne, Sanderman, D'Emilio, & McLaughlin, 2008; Hammer, Farkas, & Maczuga, 2010; Ezell & Justice 2005; McCardle, Scarborough, & Catts, 2001). These challenges can be addressed in several ways. Early intervention including parent education and collaboration along with shared book reading are considered best practices and critical to improving child outcomes (NELP, 2008). In addition, children who have a solid foundation in early literacy skills including vocabulary development in their native language will later transfer to the development of vocabulary in English (Ballantyne et al., 2008). Yet, research on shared book reading practices within the home of Hispanics is minimal (Hammer and Miccio, 2006). It is necessary to expand the literature on how to adapt best practices to meet the needs of Hispanic families who are economically disadvantaged. The purpose of this study was to investigate the impact of parent training and coaching of dialogic reading strategies in Spanish on mothers' implementation of the strategies and total vocabulary expressed by the child during shared book reading within the home environment. In addition, the researcher explored parent receptiveness towards shared book reading strategies. The research design for the study was a single-subject multiple baseline across three mother-child dyad participants. The independent variable was the intervention which consisted of parent training video on dialogic reading, parent handouts, and researcher coaching. The dependent variables were the mother's implementation of dialogic reading strategies and the children's total expressed words during shared book reading. The mother-child dyads, originally from Mexico, lived in settled migrant community in central Florida. The three children regularly attended a local federally funded preschool and received services for speech and/or language. The results indicated that the mothers' implementation of dialogic reading increased after training and coaching and the children's expressed total vocabulary words also increased. Dyad's interests in the selected books, mother responsiveness during shared book reading, and duration of shared book reading may have impacted some of the variability in the results. Furthermore, mothers were unaware of the dialogic reading strategies prior to the intervention and reported positive feedback and a desire to learn more ways to help their children at home. Implications for research and practice include the need for parent education to support caretakers of young children with speech and/or language delays, involvement of parents in the intervention planning process including coaching options, adaptation of intervention to expand upon parent's funds of knowledge, complexity of code-switching and language differences, and greater collaboration between school and home.
Show less - Date Issued
- 2011
- Identifier
- CFE0003961, ucf:48713
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003961
- Title
- A NEW FRAMEWORK FOR QOS PROVISIONING IN WIRELESS LANS USING THE P-PERSISTENT MAC PROTOCOL.
- Creator
-
Anna, Kiran Babu, Bassiouni, Mostafa, University of Central Florida
- Abstract / Description
-
The support of multimedia traffic over IEEE 802.11 wireless local area networks (WLANs) has recently received considerable attention. This dissertation has proposed a new framework that provides efficient channel access, service differentiation and statistical QoS guarantees in the enhanced distributed channel access (EDCA) protocol of IEEE 802.11e. In the first part of the dissertation, the new framework to provide QoS support in IEEE 802.11e is presented. The framework uses three...
Show moreThe support of multimedia traffic over IEEE 802.11 wireless local area networks (WLANs) has recently received considerable attention. This dissertation has proposed a new framework that provides efficient channel access, service differentiation and statistical QoS guarantees in the enhanced distributed channel access (EDCA) protocol of IEEE 802.11e. In the first part of the dissertation, the new framework to provide QoS support in IEEE 802.11e is presented. The framework uses three independent components, namely, a core MAC layer, a scheduler, and an admission control. The core MAC layer concentrates on the channel access mechanism to improve the overall system efficiency. The scheduler provides service differentiation according to the weights assigned to each Access Category (AC). The admission control provides statistical QoS guarantees. The core MAC layer developed in this dissertation employs a P-Persistent based MAC protocol. A weight-based fair scheduler to obtain throughput service differentiation at each node has been used. In wireless LANs (WLANs), the MAC protocol is the main element that determines the efficiency of sharing the limited communication bandwidth of the wireless channel. In the second part of the dissertation, analytical Markov chain models for the P-Persistent 802.11 MAC protocol under unsaturated load conditions with heterogeneous loads are developed. The Markov models provide closed-form formulas for calculating the packet service time, the packet end-to-end delay, and the channel capacity in the unsaturated load conditions. The accuracy of the models has been validated by extensive NS2 simulation tests and the models are shown to give accurate results. In the final part of the dissertation, the admission control mechanism is developed and evaluated. The analytical model for P-Persistent 802.11 is used to develop a measurement-assisted model-based admission control. The proposed admission control mechanism uses delay as an admission criterion. Both distributed and centralized admission control schemes are developed and the performance results show that both schemes perform very efficiently in providing the QoS guarantees. Since the distributed admission scheme control does not have a complete state information of the WLAN, its performance is generally inferior to the centralized admission control scheme. The detailed performance results using the NS2 simulator have demonstrated the effectiveness of the proposed framework. Compared to 802.11e EDCA, the scheduler consistently achieved the desired throughput differentiation and easy tuning. The core MAC layer achieved better delays in terms of channel access, average packet service time and end-to-end delay. It also achieved higher system throughput than EDCA for any given service differentiation ratio. The admission control provided the desired statistical QoS guarantees.
Show less - Date Issued
- 2010
- Identifier
- CFE0003243, ucf:48513
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003243
- Title
- A New Methodology for Evaluating the Effectiveness of Bus Rapid Transit Strategies.
- Creator
-
Alomari, Ahmad, Al-Deek, Haitham, Eluru, Naveen, Tatari, Omer, Maboudou, Edgard, University of Central Florida
- Abstract / Description
-
Over the last few years, public transportation has become more desirable as capacity of existing roadways failed to keep up with rapidly increasing traffic demand. Buses are one of the most common modes of public transportation with low impact on network capacity, especially in small and congested urban areas. However, the use of regularly scheduled buses as the main public transport mode can become useless with the presence of traffic congestion and dense construction areas. In cases like...
Show moreOver the last few years, public transportation has become more desirable as capacity of existing roadways failed to keep up with rapidly increasing traffic demand. Buses are one of the most common modes of public transportation with low impact on network capacity, especially in small and congested urban areas. However, the use of regularly scheduled buses as the main public transport mode can become useless with the presence of traffic congestion and dense construction areas. In cases like these, innovative solutions, such as bus rapid transit (BRT), can provide an increased level of service without having to resort to other, more expensive modes, such as light rail transit (LRT) and metro systems (subways). Transit signal priority (TSP), which provides priority to approaching buses at signalized intersections by extending the green or truncating the red, can also increase the performance of the bus service.Understanding the combined impact of TSP and BRT on network traffic operations can be complex. Although TSP has been implemented worldwide, none of the previous studies have examined in depth the effects of using conditional and unconditional TSP strategies with a BRT system. The objective of this research is to evaluate the effectiveness of BRT without TSP, then with conditional or unconditional TSP strategies. The micro-simulation software VISSIM was used to compare different TSP and BRT scenarios. These simulation scenarios include the base scenario (before implementation of the TSP and BRT systems), Unconditional TSP (TSP activates for all buses), Conditional TSP 3 minutes behind (TSP only activates for buses that are 3 minutes or more behind schedule), Conditional TSP 5 minutes behind (only activates for buses 5 minutes or more behind schedule), BRT with no TSP, BRT with Unconditional TSP, BRT with Conditional TSP 3 minutes behind, and BRT with Conditional TSP 5 minutes behind.The VISSIM simulation model was developed, calibrated and validated using a variety of data that was collected in the field. These data included geometric data, (number of lanes, intersection geometries, etc.); traffic data (average daily traffic volumes at major intersections, turning movement percentages at intersections, heavy vehicle percentages, bus passenger data, etc.); and traffic control data (signal types, timings and phasings, split history, etc.). Using this field data ensured the simulation model was sufficient for modeling the test corridor. From this model, the main performance parameters (for all vehicles and for buses only) for through movements in both directions (eastbound and westbound) along the corridor were analyzed for the various BRT/TSP scenarios. These parameters included average travel times, average speed profiles, average delays, and average number of stops. As part of a holistic approach, the effects of BRT and TSP on crossing street delay were also evaluated. Simulation results showed that TSP and BRT scenarios were effective in reducing travel times (up to 26 %) and delays (up to 64%), as well as increasing the speed (up to 47%), compared to the base scenario. The most effective scenarios were achieved by combining BRT and TSP. Results also showed that BRT with Conditional TSP 3 minutes behind significantly improved travel times (17 (-) 26%), average speed (30 (-) 39%), and average total delay per vehicle (11 (-) 32%) for the main corridor through movements compared with the base scenario, with only minor effects on crossing street delays. BRT with Unconditional TSP resulted in significant crossing street delays, especially at major intersections with high traffic demand, which indicates that this scenario is impractical for implementation in the corridor. Additionally, BRT with Conditional TSP 3 minutes behind had better travel time savings than BRT with Conditional TSP 5 minutes behind for both travel directions, making this the most beneficial scenario.This research provided an innovative approach by using nested sets (hierarchical design) of TSP and BRT combination scenarios. Coupled with microscopic simulation, nested sets in the hierarchical design are used to evaluate the effectiveness of BRT without TSP, then with conditional or unconditional TSP strategies. The robust methodology developed in this research can be applied to any corridor to understand the combined TSP and BRT effects on traffic performance. Presenting the results in an organized fashion like this can be helpful in decision making. This research investigated the effects of BRT along I-Drive corridor (before and after conditions) at the intersection level. Intersection analysis demonstrated based on real life data for the before and after the construction of BRT using the Highway Capacity SoftwareTM (HCS2010) that was built based on the Highway Capacity Manual (HCM 2010) procedures for urban streets and signalized intersections. The performance measure used in this analysis is the level of service (LOS) criteria which depends on the control delay (seconds per vehicle) for each approach and for the entire intersection. The results show that implementing BRT did not change the LOS. However, the control delay has improved at most of the intersections' approaches. The majority of intersections operated with an overall LOS "C" or better except for Kirkman Road intersection (T2) with LOS "E" because it has the highest traffic volumes before and after BRT construction.This research also used regression analysis to observe the effect of the tested scenarios analyzed in VISSIM software compared to the No TSP (-) No BRT base model for all vehicles and for buses only. The developed regression model can predict the effect of each scenario on each studied Measures of Performance (MOE). Minitab statistical software was used to conduct this multiple regression analysis. The developed models with real life data input are able to predict how proposed enhancements change the studied MOEs. The BRT models presented in this research can be used for further sensitivity analysis on a larger regional network in the upcoming regional expansion of the transit system in Central Florida. Since this research demonstrated the operational functionality and effectiveness of BRT and TSP systems in this critical corridor in Central Florida, these systems' accomplishments can be expanded throughout the state of Florida to provide greater benefits to transit passengers. Furthermore, to demonstrate the methodology developed in this research, it is applied to a test corridor along International Drive (I-Drive) in Orlando, Florida. This corridor is key for regional economic prosperity of Central Florida and the novel approach developed in this dissertation can be expanded to other transit systems.
Show less - Date Issued
- 2015
- Identifier
- CFE0005918, ucf:50848
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005918
- Title
- THE EFFECT OF IMMEDIATE FEEDBACK AND AFTER ACTION REVIEWS (AARS) ON LEARNING, RETENTION AND TRANSFER.
- Creator
-
Sanders, Michael, Williams, Kent, University of Central Florida
- Abstract / Description
-
An After Action Review (AAR) is the Army training system's performance feedback mechanism. The purpose of the AAR is to improve team (unit) and individual performance in order to increase organizational readiness. While a large body of knowledge exists that discusses instructional strategies, feedback and training systems, neither the AAR process nor the AAR systems have been examined in terms of learning effectiveness and efficiency for embedded trainers as part of a holistic training system...
Show moreAn After Action Review (AAR) is the Army training system's performance feedback mechanism. The purpose of the AAR is to improve team (unit) and individual performance in order to increase organizational readiness. While a large body of knowledge exists that discusses instructional strategies, feedback and training systems, neither the AAR process nor the AAR systems have been examined in terms of learning effectiveness and efficiency for embedded trainers as part of a holistic training system. In this thesis, different feedback methods for embedded training are evaluated based on the timing and type of feedback used during and after training exercises. Those feedback methodologies include: providing Immediate Directive Feedback (IDF) only, the IDF Only feedback condition group; using Immediate Direct Feedback and delayed feedback with open ended prompts to elicit self-elaboration during the AAR, the IDF with AAR feedback condition group; and delaying feedback using opened ended prompts without any IDF, the AAR Only feedback condition group. The results of the experiment support the hypothesis that feedback timing and type do effect skill acquisition, retention and transfer in different ways. Immediate directive feedback has a significant effect in reducing the number of errors committed while acquiring new procedural skills during training. Delayed feedback, in the form of an AAR, has a significant effect on the acquisition, retention and transfer of higher order conceptual knowledge as well as procedural knowledge about a task. The combination of Immediate Directive Feedback with an After Action Review demonstrated the greatest degree of transfer on a transfer task.
Show less - Date Issued
- 2005
- Identifier
- CFE0000441, ucf:46411
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000441
- Title
- RIGHT TURN SPLIT: A NEW DESIGN TO ALLEVIATE WEAVING ON ARTERIAL STREETS.
- Creator
-
Shaaban, Khaled, Radwan, Essam, University of Central Florida
- Abstract / Description
-
While weaving maneuvers occur on every type of roadway, most studies have focused on freeway maneuvers. Weaving occurring on non-freeway facilities, such as arterial streets, can cause significant operational problems. Arterial streets weaving typically occur when vehicles coming from a side street at an upstream intersection attempt to enter the main street from one side to reach access points on the opposite site at a downstream intersection by crossing one or more lanes. This dissertation...
Show moreWhile weaving maneuvers occur on every type of roadway, most studies have focused on freeway maneuvers. Weaving occurring on non-freeway facilities, such as arterial streets, can cause significant operational problems. Arterial streets weaving typically occur when vehicles coming from a side street at an upstream intersection attempt to enter the main street from one side to reach access points on the opposite site at a downstream intersection by crossing one or more lanes. This dissertation investigates the type of problems occurring on arterial streets due to the weaving movements and recommends a new design to alleviate weaving on arterial streets. Firstly, the dissertation examined the different weaving movements occurring between two close-spaced intersections at two sites in Florida and explained the breakdown conditions caused by the weaving movements at the two sites. Secondly, the dissertation proposed a new design, Right Turn Split (RTS), to alleviate the delay caused by the weaving movements. The new design proposed separating the worst weaving movement entering the arterial from the other movements and providing a separate path for this movement. The new method is easy to implement and does not require much right of way. Thirdly, the dissertation compared two microscopic models, SimTraffic and VISSIM, to choose the most suitable model to be used to study the operational benefits of the RTS design. Based on the results of the comparison, it was decided to use SimTraffic for the analysis. Fourthly, the dissertation proposed a new calibration and validation procedure for microscopic simulation models. The procedure was applied on SimTraffic using the traffic data from the two studied sites. The proposed procedure appeared to be properly calibrating and validating the SimTraffic simulation model. Finally, the calibrated and validated model was used to study the operational benefits of the RTS design. Using a wide range of geometric and volume conditions, 729 before and after pairs were created to compare the delay of similar scenarios before and after applying the RTS design. The results were analyzed graphically and statistically. The findings of the analysis showed that the RTS design provided lower delay on the arterial street than the original conditions.
Show less - Date Issued
- 2005
- Identifier
- CFE0000402, ucf:46346
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000402
