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- Title
- EFFECTS OF THE SOIL PROPERTIES ON THE MAXIMUM DRY DENSITY OBTAINED FROM THE STANDARD PROCTOR TEST.
- Creator
-
Arvelo, Andres, Kuo, Shiou-san, University of Central Florida
- Abstract / Description
-
In the construction of highways, airports, and other structures, the compaction of soils is needed to improve its strength. In 1933 Proctor developed a laboratory compaction test to determine the maximum dry density of compacted soils, which can be used for specifications of field compaction. The Compaction of soils is influenced by many factors, the most common are the moisture content, the soil type and the applied compaction energy. The objective of this research is the analysis of the...
Show moreIn the construction of highways, airports, and other structures, the compaction of soils is needed to improve its strength. In 1933 Proctor developed a laboratory compaction test to determine the maximum dry density of compacted soils, which can be used for specifications of field compaction. The Compaction of soils is influenced by many factors, the most common are the moisture content, the soil type and the applied compaction energy. The objective of this research is the analysis of the maximum dry density values based on the soil classification and characterization. The method of choice in the determination of the maximum dry density from different soils was the Standard Proctor Test following the procedure for the standard Proctor test as is explained in ASTM Test Designation D-698. From this investigation, the maximum dry density of eight types of sands was obtained, the sands were classified by using the Unified Soil Classification System. The influence on the maximum dry density of the type of sands, type of fines, amount of fines and distribution of the grain size was determined, followed by a sensitivity analysis that measured the influence of these parameters on the obtained maximum dry density. The research revealed some correlations between the maximum dry density of soils with the type of fines, the fines content and the Uniformity Coefficient. These correlations were measured and some particular behavioral trends were encountered and analyzed. It was found that well-graded sands have higher maximum dry density than poorly graded when the soils have the same fines content, also it was encountered that plastic fines tend to increase the maximum dry density.
Show less - Date Issued
- 2004
- Identifier
- CFE0000261, ucf:46237
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000261
- Title
- PERFORMANCE SUPPORT AND USABILITY:AN EXPERIMENTAL STUDY OFELECTRONIC PERFORMANCE SUPPORT INTERFACES.
- Creator
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Rawls, Charles, Hirumi, Atsusi, University of Central Florida
- Abstract / Description
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This study evaluated the usability of two types of performance-support interfaces that were designed using informational and experiential approaches. The experiment sought to determine whether there is a relationship between usability and the informational and experiential approaches. The general population under study was undergraduate education major students from the University of Central Florida. From the general population of three educational technology instructor-led classes, 83...
Show moreThis study evaluated the usability of two types of performance-support interfaces that were designed using informational and experiential approaches. The experiment sought to determine whether there is a relationship between usability and the informational and experiential approaches. The general population under study was undergraduate education major students from the University of Central Florida. From the general population of three educational technology instructor-led classes, 83 students were solicited to participate in the study by completing a class activity. From the general population, a total of 63 students participated in the study. By participating in the study, the students completed a task and a questionnaire. Students were predominantly English-speaking Caucasian female education majors between the ages of 19 and 20; most of them were sophomores or juniors working part time. They possessed moderately low to high computer skills and most considered themselves to have intermediate or expert Internet skills. An experimental posttest-only comparison group research design was used to test the hypotheses posited for this study. The participants were randomly assigned to either the informational interface group (X1) or the experiential interface group (X2), and the experiment was conducted electronically via a Web-based Content Management System (CMS). The observed data consisted of five outcome measures: efficiency, errors, intuitiveness, satisfaction, and student performance. Two instruments--a checklist and an online usability questionnaire--were used to measure the five dependent variables: efficiency, intuitiveness, errors, satisfaction, and student performance. The CMS was used as the vehicle to distribute and randomize the two interfaces, obtain informed consent, distribute the instructions, distribute the online questionnaire, and collect data. First, a checklist was used to assess the students' performance completing their task, which was a copyright issue request letter. The checklist was designed as a performance criterion tool for the researcher, instructor, and participants to use. The researcher and instructor constructed the checklist to grade copyright request letters and determine students' performance. The participants had the opportunity to use the checklist as a performance criterion to create the task document (copyright request letter). The checklist consisted of ten basic yet critical sections of a successful copyright request letter. Second, an online usability questionnaire was constructed based on the Purdue Usability Testing Questionnaire (PUTQ) questions to measure interface efficiency, intuitiveness, errors, and satisfaction. While these test items have been deemed important for testing the usability of a particular system, for purposes of this study, test items were modified, deleted, and added to ensure content validity. The new survey, University of Central Florida Usability Questionnaire (UCFUQ), consisting of 20 items, was implemented in a pilot study to ensure reliability and content validity. Changes to the PUTQ were modified to fulfill a blueprint. A pilot study of the instrument yielded a reliability coefficient of .9450, and the final online usability instrument yielded a reliability coefficient of .9321. This study tested two approaches to user interface design for the Electronic Performance Support (EPS) using two HTML interface templates and the information from an existing training module. There were two interventions consisting of two interface types: informational and experiential. The SPSS Graduate Pack 10.0 for Windows was used for data analysis and statistical reporting in this study. A t test was conducted to determine if a difference existed between the two interface means. ANOVA was conducted to determine if there was an interaction between the interface group means and the demographic data factored among the five dependent variables. Results of this study indicated that students at the University of Central Florida reported no differences between the two interface types. It was postulated that the informational interface would yield a higher mean score because of its implementation of HCI guidelines, conventions, and standards. However, it was concluded that the informational interface may not be a more usable interface. Users may be as inclined to use the experiential interface as the informational interface.
Show less - Date Issued
- 2005
- Identifier
- CFE0000807, ucf:46678
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000807
- Title
- A PROBE INTO LEARNING APPROACHES AND ATTITUDES TOWARDS TECHNOLOGY-ENHANCED LANGUAGE LEARNING (TELL) IN CHINESE INSTRUCTION.
- Creator
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Yuan, Rong, Orwig, Gary, University of Central Florida
- Abstract / Description
-
This quantitative research, carried out at the military environment at the Defense Language Institute investigated whether learning approaches could predict learners' language proficiency and learners' attitude towards technology-enhanced language learning (TELL). In addition, it also examined whether learners' demographic factors, such as age, educational backgrounds, prior experience in foreign language learning and in TELL as well as their ability to use PC and the World Wide Web could...
Show moreThis quantitative research, carried out at the military environment at the Defense Language Institute investigated whether learning approaches could predict learners' language proficiency and learners' attitude towards technology-enhanced language learning (TELL). In addition, it also examined whether learners' demographic factors, such as age, educational backgrounds, prior experience in foreign language learning and in TELL as well as their ability to use PC and the World Wide Web could predict the above mentioned language proficiency and attitude. A cluster sampling method was adopted and data was collected in four Chinese departments at the institute. Both the learning approaches inventory ASSIST and the attitudes towards TELL survey were administered to 158 Chinese language learners. 137 valid responses were obtained. All data were input into SPSS for regression and correlation analyses. Conclusions of the study are as follows: 1. The surface and apathetic approach (p<.01) was a significant predictor for both learners' measured language proficiency and their self-perception of academic performance. 2. The strategic approach was a positive predictor for learners' attitudes towards TELL; whereas, surface and apathetic approach was a negative predictor for learners' attitudes towards TELL. 3. None of the learners' demographic variables could not predict either learners' language proficiency or their attitudes towards TELL. Implications for instructional design, curriculum development, teacher education, as well as relevant research issues were discussed.
Show less - Date Issued
- 2005
- Identifier
- CFE0000829, ucf:46675
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000829
- Title
- THE INTEGRATION OF AUDIO INTO MULTIMODAL INTERFACES: GUIDELINES AND APPLICATIONS OF INTEGRATING SPEECH, EARCONS, AUDITORY ICONS, AND SPATIAL AUDIO (SEAS).
- Creator
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Jones, David, Stanney, Kay, University of Central Florida
- Abstract / Description
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The current research is directed at providing validated guidelines to direct the integration of audio into human-system interfaces. This work first discusses the utility of integrating audio to support multimodal human-information processing. Next, an auditory interactive computing paradigm utilizing Speech, Earcons, Auditory icons, and Spatial audio (SEAS) cues is proposed and guidelines for the integration of SEAS cues into multimodal systems are presented. Finally, the results of two...
Show moreThe current research is directed at providing validated guidelines to direct the integration of audio into human-system interfaces. This work first discusses the utility of integrating audio to support multimodal human-information processing. Next, an auditory interactive computing paradigm utilizing Speech, Earcons, Auditory icons, and Spatial audio (SEAS) cues is proposed and guidelines for the integration of SEAS cues into multimodal systems are presented. Finally, the results of two studies are presented that evaluate the utility of using SEAS cues, developed following the proposed guidelines, in relieving perceptual and attention processing bottlenecks when conducting Unmanned Air Vehicle (UAV) control tasks. The results demonstrate that SEAS cues significantly enhance human performance on UAV control tasks, particularly response accuracy and reaction time on a secondary monitoring task. The results suggest that SEAS cues may be effective in overcoming perceptual and attentional bottlenecks, with the advantages being most revealing during high workload conditions. The theories and principles provided in this paper should be of interest to audio system designers and anyone involved in the design of multimodal human-computer systems.
Show less - Date Issued
- 2005
- Identifier
- CFE0000810, ucf:46689
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000810
- Title
- UNIFIED LARGE AND SMALL SIGNAL DISCRETE-SPACE MODELING FOR PWM CONVERTERS IN CCM.
- Creator
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Shoubaki, Ehab, Batarseh, Issa, University of Central Florida
- Abstract / Description
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In this Thesis a Unified Discrete State-Space Model for power converters in CCM is presented. Two main approaches to arriving at the discrete model are used. The first approach involves an impulse function approximation of the duty cycle modulations of the converter switches , and this approach results in a small signal discrete model. The Second approach is direct and does not involve any approximation of the modulations , this approach yields both a large signal nonlinear discrete model and...
Show moreIn this Thesis a Unified Discrete State-Space Model for power converters in CCM is presented. Two main approaches to arriving at the discrete model are used. The first approach involves an impulse function approximation of the duty cycle modulations of the converter switches , and this approach results in a small signal discrete model. The Second approach is direct and does not involve any approximation of the modulations , this approach yields both a large signal nonlinear discrete model and a linear small signal model. Harmonic analysis of the converter states at steady-state is done for steady-state waveform acquisition , which increases the accuracy of the model especially for finding the control to inductor current frequency response. Finally the Discrete model is verified for the Half-Bridge DC/DC topology for its three main control schemes (Asymmetric , Symmetric , DCS). A GUI platform in MATLAB is presented as a wrapper that utilizes the models and analysis presented in this thesis.
Show less - Date Issued
- 2005
- Identifier
- CFE0000710, ucf:46607
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000710
- Title
- IDENTIFICATION OF SYSTEM DESIGN FEATURES THAT AFFECT SICKNESS IN VIRTUAL ENVIRONMENTS.
- Creator
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Drexler, Julie, Malone, Linda, University of Central Florida
- Abstract / Description
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The terms "simulator" and "VR" are typically used to refer to specific types of virtual environments (VEs) which differ in the technology used to display the simulated environment. While simulators and VR devices may offer advantages such as low cost training, numerous studies on the effects to humans of exposure to different VEs indicate that motion sickness-like symptoms are often produced during or after exposure to the simulated environment. These deleterious side effects have the...
Show moreThe terms "simulator" and "VR" are typically used to refer to specific types of virtual environments (VEs) which differ in the technology used to display the simulated environment. While simulators and VR devices may offer advantages such as low cost training, numerous studies on the effects to humans of exposure to different VEs indicate that motion sickness-like symptoms are often produced during or after exposure to the simulated environment. These deleterious side effects have the potential to limit the utilization of VE systems if they jeopardize the health and/or safety of the user and create liability issues for the manufacturer. The most widely used method for assessing the adverse symptoms of VE exposure is the Simulator Sickness Questionnaire (SSQ). The method of scoring the symptoms reported by VE users permits the different sickness symptoms to be clustered into three general types of effects or subscales and the distribution or pattern of the three SSQ subscales provides a profile for a given VE device. In the current research, several different statistical analyses were conducted on the SSQ data obtained from 21 different simulator studies and 16 different VR studies in order to identify an underlying symptom structure (i.e., SSQ profile) or severity difference for various types of VE systems. The results of the research showed statistically significant differences in the SSQ profiles and the overall severity of sickness between simulator and VR systems, which provide evidence that simulator sickness and VR sickness represent distinct forms of motion sickness. Analyses on three types of simulators (i.e., Fixed- and Rotary-Wing flight simulators and Driving simulators) also found significant differences in the sickness profiles as well as the overall severity of sickness within different types of simulator systems. Analyses on three types of VR systems (i.e., HMD, BOOM, and CAVE) revealed that BOOM and CAVE systems have similar sickness profiles, which are different than the HMD system profile. Moreover, the results showed that the overall severity of sickness was greater in HMD systems than in BOOM and CAVE systems. Recommendations for future research included additional psychophysical studies to evaluate the relationship between various engineering characteristics of VE systems and the specific types of sickness symptoms that are produced from exposure to them.
Show less - Date Issued
- 2006
- Identifier
- CFE0000989, ucf:46700
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000989
- Title
- ARE BUILDING DESIGN RATING SYSTEMS EFFECTIVE TOWARDS THE GOAL OF SUSTAINABILITY IN THE DESIGN AND CONSTRUCTION OF PUBLIC AND PRIVATE BUILDINGS AND HOW WILL NEW ENERGY PERFORMANCE AND SUSTAINABLE DESIGN REQUIREMENTS AFFECT THE PROFESSIONAL LIABILITY OF BUILDING DESIGN PROFESSIONALS?.
- Creator
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Transue, Samuel, Milon, Abby, University of Central Florida
- Abstract / Description
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The following paper will explore the future of sustainable building practices as it relates to building design rating systems and whether building design rating systems are effective in conserving energy and resources in the construction of new buildings. This paper will begin by highlighting some of the general principles behind sustainable design practices, and the challenges of determining if building design rating systems are utilized effectively towards the goal of sustainability. In...
Show moreThe following paper will explore the future of sustainable building practices as it relates to building design rating systems and whether building design rating systems are effective in conserving energy and resources in the construction of new buildings. This paper will begin by highlighting some of the general principles behind sustainable design practices, and the challenges of determining if building design rating systems are utilized effectively towards the goal of sustainability. In addition, the paper will highlight issues specific to ongoing litigation in Gifford v. U.S. Green Building Council and allegations made within the lawsuit that question the methodology and efficacy of building design rating systems. How political and ideological influences have propelled sustainability practices into the mainstream, and to what extent government is and should be involved in regulating building design rating systems will also be explored. Lastly, how will new energy performance and sustainable design methodologies, which are now being required in the law, affect the professional liability of building design professionals in the future?
Show less - Date Issued
- 2011
- Identifier
- CFH0004066, ucf:44788
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004066
- Title
- OPTIMIZING DYNAMIC LOGIC REALIZATIONS FOR PARTIAL RECONFIGURATION OF FIELD PROGRAMMABLE GATE ARRAYS.
- Creator
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Parris, Matthew, DeMara, Ronald, University of Central Florida
- Abstract / Description
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Many digital logic applications can take advantage of the reconfiguration capability of Field Programmable Gate Arrays (FPGAs) to dynamically patch design flaws, recover from faults, or time-multiplex between functions. Partial reconfiguration is the process by which a user modifies one or more modules residing on the FPGA device independently of the others. Partial Reconfiguration reduces the granularity of reconfiguration to be a set of columns or rectangular region of the device....
Show moreMany digital logic applications can take advantage of the reconfiguration capability of Field Programmable Gate Arrays (FPGAs) to dynamically patch design flaws, recover from faults, or time-multiplex between functions. Partial reconfiguration is the process by which a user modifies one or more modules residing on the FPGA device independently of the others. Partial Reconfiguration reduces the granularity of reconfiguration to be a set of columns or rectangular region of the device. Decreasing the granularity of reconfiguration results in reduced configuration filesizes and, thus, reduced configuration times. When compared to one bitstream of a non-partial reconfiguration implementation, smaller modules resulting in smaller bitstream filesizes allow an FPGA to implement many more hardware configurations with greater speed under similar storage requirements. To realize the benefits of partial reconfiguration in a wider range of applications, this thesis begins with a survey of FPGA fault-handling methods, which are compared using performance-based metrics. Performance analysis of the Genetic Algorithm (GA) Offline Recovery method is investigated and candidate solutions provided by the GA are partitioned by age to improve its efficiency. Parameters of this aging technique are optimized to increase the occurrence rate of complete repairs. Continuing the discussion of partial reconfiguration, the thesis develops a case-study application that implements one partial reconfiguration module to demonstrate the functionality and benefits of time multiplexing and reveal the improved efficiencies of the latest large-capacity FPGA architectures. The number of active partial reconfiguration modules implemented on a single FPGA device is increased from one to eight to implement a dynamic video-processing architecture for Discrete Cosine Transform and Motion Estimation functions to demonstrate a 55-fold reduction in bitstream storage requirements thus improving partial reconfiguration capability.
Show less - Date Issued
- 2008
- Identifier
- CFE0002323, ucf:47793
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002323
- Title
- Experimental and numerical investigation of a novel adsorption bed design for cooling applications.
- Creator
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Abdelhady, Ramy, Chow, Louis, Mansy, Hansen, Das, Tuhin, Duranceau, Steven, University of Central Florida
- Abstract / Description
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A global challenge is to develop environmentally friendly, affordable, compact and sustainable technologies to provide heating and cooling power. Adsorption cooling (AC) technology is one of the most promising ways to solve the environmental issues and cut down the energy consumption related to the traditional air conditioning and refrigeration systems. However, AC systems still suffer from poor heat and mass transfer inside the adsorption bed, which is the main obstacle to commercialization...
Show moreA global challenge is to develop environmentally friendly, affordable, compact and sustainable technologies to provide heating and cooling power. Adsorption cooling (AC) technology is one of the most promising ways to solve the environmental issues and cut down the energy consumption related to the traditional air conditioning and refrigeration systems. However, AC systems still suffer from poor heat and mass transfer inside the adsorption bed, which is the main obstacle to commercialization of adsorption cooling units. The main goal of this study is designing an efficient adsorption cooling cycle. In this research work, an in-depth scaling analysis of heat and mass transfer in an adsorption packed bed has been performed to identify and quantify how the effective thermal diffusivity of an adsorption bed and the surface diffusion rate of an adsorbate in a nanoporous adsorbent affect the specific cooling power of an adsorption cooling system. The main goal of this study is to derive new scaling parameters that can be used to specify the optimal bed dimensions and select the appropriate adsorbate/adsorbent pair to achieve the maximum cooling power. As the choice of a suitable working pair is critical for an adsorption cooling cycle, an experimental setup is designed and built to measure the adsorption kinetics and isotherms of any working pair accurately. This setup is also able to measure the dynamic performance of an adsorption bed. The equilibrium uptakes of Fuji silica-gels Type-RD and RD-2060 (manufactured by Fuji Silysia, Japan), which are commonly used in adsorption cooling systems, are measured experimentally. Based on the adsorption rate and the adsorbent temperature measured simultaneously, a new approach is proposed to measure the surface diffusivity in the temperature and pressure ranges typical of those during the operating conditions of adsorption cooling systems. In addition, the experimental measurements from the lab-scale adsorption bed are used to validate the numerical models that are commonly used for estimating the SCP of AC cycle. By using the scaling parameters driven from the scaling analysis, a newly designed packed bed for use in AC systems is proposed and evaluated in this research. The proposed design consists of repeated packed bed cells (modules). Each module is an open-cell aluminum foam packed with silica gel to enhance the overall thermal conductivity of the bed from 0.198 to 5.8 W/m.K. the experimental test rig is used to evaluate the performance on the new adsorption bed. The effect of pores per inch (PPI) of the foam, silica-gel particle size, bed height and adsorption isotherm of different types of silica gel on the bed performance are investigated.
Show less - Date Issued
- 2019
- Identifier
- CFE0007422, ucf:52702
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007422
- Title
- Do per-capita impact or abundance dominate the impact of an invader? Interactions among neighboring species in context-dependent competition.
- Creator
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Li, Haoyu, Quintana-Ascencio, Pedro, Jenkins, David, Boughton, Elizabeth, University of Central Florida
- Abstract / Description
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Evaluating relative species competitive strength is a central question in community ecology, with strong implications for invasion ecology. Models assessing invader success consider three components: distribution, abundance and per-capita impact. However, relative strength and interactions among these factors remain unclear when applying to specific invasion scenarios. We hypothesized that performance of native and non-native species will vary as a function of direct and indirect effects at...
Show moreEvaluating relative species competitive strength is a central question in community ecology, with strong implications for invasion ecology. Models assessing invader success consider three components: distribution, abundance and per-capita impact. However, relative strength and interactions among these factors remain unclear when applying to specific invasion scenarios. We hypothesized that performance of native and non-native species will vary as a function of direct and indirect effects at different abundances and scales. We conducted a replacement experiment between two dominant grasses in subtropical grasslands (the native Axonopus fissifolius and the non-native Paspalum notatum) in central Florida, USA. Thirty fenced plots (1 m x 3 m each) representing a gradient (15 levels) of increasing non-native groundcover and decreasing native groundcover were set up in November 2017. We transplanted individuals of these two species in subplots (12 subplots and 36 transplants per plot; 1080 plants in total) in a 2*2 factorial design (mixed /single focal species * 2/4 transplants per subplot). Leaf length/number and plant biomass were evaluated at the beginning and end of the experiment along with plot species composition and soil nutrients. Over 92% of transplants of each grass species survived until harvest (11 months). There were significant differences in leaf length, leaf number and plant biomass between conspecific/allospecific subplots. Both P. notatum and A. fissifolius performed better when transplanted in non-native P. notatum subplots. There were also interactions between conspecific/allospecific subplot treatment (direct effects) and the gradient of increasing Paspalum notatum /decreasing Axonopus fissifolius groundcover (indirect effects) treatments. Increasing P. notatum in the whole plot made environments more favorable for both grass species. Effects were consistent for leaf length/number and biomass of the two focal species. More comprehensive evaluation on indirect effects need to be considered when examining competition between non-native species and native species.
Show less - Date Issued
- 2019
- Identifier
- CFE0007487, ucf:52685
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007487
- Title
- Investigating Instructional Designers' Decisions Regarding The Use Of Multimedia Learning Principles in E-learning Course Design.
- Creator
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Arguelles, Victor, Hartshorne, Richard, Gill, Michele, Vitale, Thomas, Swan, Bonnie, University of Central Florida
- Abstract / Description
-
This study employed a qualitative research design using the Decomposed Theory of Planned Behavior (DTPB) to investigate instructional designers' use of multimedia learning principles (MLPs) in e-learning course design. While MLPs have been extensively studied in educational research and are largely associated with positive results, evidence suggests that instructional designers are not uniformly implementing these strategies when designing e-learning environments. The purpose of this study...
Show moreThis study employed a qualitative research design using the Decomposed Theory of Planned Behavior (DTPB) to investigate instructional designers' use of multimedia learning principles (MLPs) in e-learning course design. While MLPs have been extensively studied in educational research and are largely associated with positive results, evidence suggests that instructional designers are not uniformly implementing these strategies when designing e-learning environments. The purpose of this study was twofold: (a) to understand better the alignment between instructional designers' knowledge and demonstrated implementation of MLPs; and (b) to understand the factors that influence instructional designers' intent and actual implementation of MLPs in their e-learning course design. Based on two interviews conducted with seven instructional designers and an analysis of representative work samples, this study produced seven findings. Participants were recruited using homogenous purposive sampling method from two small corporate organizations whose primary business is the development of e-learning environments. Overall, these findings suggest that, despite being exposed to MLPs and holding positive behavioral beliefs regarding the usefulness of them, instructional designers may hold negative beliefs and face constraining conditions that pose significant barriers to the utilization of MLPs in e-learning course design. Other findings regarding MLP use in design are discussed and future directions for practice, policy, and research are offered.
Show less - Date Issued
- 2017
- Identifier
- CFE0006716, ucf:51898
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006716
- Title
- Kindergarten through twelfth grade student perception of online courses and qualities that lead to course completion.
- Creator
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Peterson, Jennifer, Gunter, Glenda, Swan, Bonnie, Vitale, Thomas, Taylor, Rosemarye, University of Central Florida
- Abstract / Description
-
The purpose of this study was two-fold, to understand student perception of the supplemental online courses and improve the online learning program at ABC Online Learning School. The study focused on students in Grades 6 -12 who belonged to the ABC School District and enrolled ABC Online Learning School high school credit courses to supplement their education. Student participants were asked to complete the Student Survey of Online Course Design. The data retrieved from the survey was...
Show moreThe purpose of this study was two-fold, to understand student perception of the supplemental online courses and improve the online learning program at ABC Online Learning School. The study focused on students in Grades 6 -12 who belonged to the ABC School District and enrolled ABC Online Learning School high school credit courses to supplement their education. Student participants were asked to complete the Student Survey of Online Course Design. The data retrieved from the survey was analyzed using the Spearman correlation to establish the strength of the relationship between student perception of quality online course design and the importance of specific components of the online course. The results indicated that as student perception of quality increased, their perception of the importance of the component increased as well. Additionally, a logistic regression formula was used to test the ability to predict successful online course completions based on the developer of the online course (instructor-developed or vendor-developed) and the type of credit the student would earn based on completion (original credit or credit retrieval/recovery). The results of the analysis of the logistic regression showed that developer of the online course and type of credit earned did not have a significant influence on successful course completions. The study is significant because, in Florida, K-12 online courses are funded based on successful course completion and students are required to successful complete an online course to earn a high school diploma.
Show less - Date Issued
- 2018
- Identifier
- CFE0007356, ucf:52099
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007356
- Title
- Catalyst Design and Mechanism Study with Computational Method for Small Molecule Activation.
- Creator
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Liu, Muqiong, Zou, Shengli, Harper, James, Dixon, Donovan, Chen, Gang, Feng, Xiaofeng, University of Central Florida
- Abstract / Description
-
Computational chemistry is a branch of modern chemistry that utilizes the computers to solve chemical problems. The fundamental of computational chemistry is Schr(&)#246;dinger equation. To solve the equation, researchers developed many methods based on Born-Oppenheimer Approximation, such as Hartree-Fock method and DFT method, etc. Computational chemistry is now widely used on reaction mechanism study and new chemical designing.In the first project described in Chapter 3, we designed...
Show moreComputational chemistry is a branch of modern chemistry that utilizes the computers to solve chemical problems. The fundamental of computational chemistry is Schr(&)#246;dinger equation. To solve the equation, researchers developed many methods based on Born-Oppenheimer Approximation, such as Hartree-Fock method and DFT method, etc. Computational chemistry is now widely used on reaction mechanism study and new chemical designing.In the first project described in Chapter 3, we designed phosphine oxide modified Ag3, Au3 and Cu3 nanocluster catalysts with DFT method. We found that these catalysts were able to catalyze the activation of H2 by cleaving the H-H bond asymmetrically. The activated catalyst-2H complex can be further used as reducing agent to hydrogenate CO molecule to afford HCHO. The mechanism study of these catalysts showed that the electron transfer from electron-rich metal clusters to O atom on the phosphine oxide ligand is the major driving force for H2 activation. In addition, different substituent groups on phosphine oxide ligand were tested. Both H affinity of metal and the substituent groups on ligand can both affect the activation energy.Another project described in Chapter 4 is the modelling of catalyst with DFT. We chose borane/NHC frustrated Lewis pair (FLP) catalyzed methane activation reaction as example to establish a relationship between activation energy and catalysts' physical properties. After performing simulation, we further proved the well-accepted theory that the electron transfer is the main driving force of catalysis. Furthermore, we were able to establish a linearivrelationship for each borane between activation energy and the geometrical mean value of HOMO/LUMO energy gap (?EMO). Based on that, we introduced the formation energy of borane/NHC complex (?EF) and successfully established a generalized relationship between Ea and geometrical mean value of ?EMO and ?EF. This model can be used to predict reactivity of catalysts.
Show less - Date Issued
- 2018
- Identifier
- CFE0007343, ucf:52112
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007343
- Title
- Developing Warrants for Designing Continuous Flow Intersection and Diverging Diamond Interchange.
- Creator
-
Almoshaogeh, Meshal, Radwan, Essam, Abdel-Aty, Mohamed, Abou-Senna, Hatem, University of Central Florida
- Abstract / Description
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The main goal of this dissertation is to have better understanding of design and operation of the Continuous Flow Intersection (CFI) and Diverging Diamond Interchange (DDI) - as well as numerous factors that affect signalized intersection and interchange performance due to increased left-turn demand. The dissertation attempts to assess the need and justification to redesign intersections and interchanges to improve their efficiency. And to that end, an extensive literature review of existing...
Show moreThe main goal of this dissertation is to have better understanding of design and operation of the Continuous Flow Intersection (CFI) and Diverging Diamond Interchange (DDI) - as well as numerous factors that affect signalized intersection and interchange performance due to increased left-turn demand. The dissertation attempts to assess the need and justification to redesign intersections and interchanges to improve their efficiency. And to that end, an extensive literature review of existing studies was done with the prime aim of perceiving the principles of these innovative designs and determining the methodology to-be-followed, in order to reach the study's core. Accordingly, several DDI and CFI locations were selected as candidate locations, where the designs have already been implemented and the required data - to model calibration and validation - was collected. The micro-simulation software (VISSIM 8.0) was used for simulation, calibration and validation of the existing conditions - through several steps - including signal optimization and driving behavior parameter sensitivity analysis. Subsequently, an experiment was conceived for each design, aiming at examining several factors that affect each design's efficiency. The experiment comprised 180 and 90 different CFI (&) DDI scenarios and their conventional designs, respectively. Two measures of effectiveness were identified for result analysis: the average delay and capacity. Result analyses were performed to detect switching thresholds (from conventional to innovative designs. In addition, performance comparison studies of the CFI and DDI with their conventional designs were performed. The results and findings will serve as guidelines for decision-makers as to when they should consider switching from conventional to innovative design. Finally, decision support systems were developed to speed up the search for the superior design, in comparison with others.
Show less - Date Issued
- 2017
- Identifier
- CFE0007276, ucf:52187
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007276
- Title
- Gate and throughput optimizations for null convention self-timed digital circuits.
- Creator
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Smith, Scott Christopher, DeMara, Ronald, Engineering and Computer Science
- Abstract / Description
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University of Central Florida College of Engineering Thesis; Convention Logic (NCL) provides an asynchronous design methodology employing dual-rail signals, quad-rail signals, or other Mutually Exclusive Assertion Groups (MEAGs) to incorporate data and control information into one mixed path. In NCL, the control is inherently present with each datum, so there is no need for worse case delay analysis and control path delay matching. This dissertation focuses on optimization methods for NCL...
Show moreUniversity of Central Florida College of Engineering Thesis; Convention Logic (NCL) provides an asynchronous design methodology employing dual-rail signals, quad-rail signals, or other Mutually Exclusive Assertion Groups (MEAGs) to incorporate data and control information into one mixed path. In NCL, the control is inherently present with each datum, so there is no need for worse case delay analysis and control path delay matching. This dissertation focuses on optimization methods for NCL circuits, specifically addressing three related architectural areas of NCL design. First, a design method for optimizing NCL circuits is developed. The method utilizes conventional Boolean minimization followed by table-driven gate substitutions. It IS applied to design time and space optimal fundamental logic functions, a time and space optimal full adder, and time, transistor count, and power optimal up-counter circuits. The method is applicable when composing logic functions where each gate is a state-holding element; and can produce delay-insensitive circuits requiring less area and fewer gate delays than alternative gate-level approaches requiring full minterm generation. Second, a pipelining method for producing throughput optimal NCL systems is developed. A relationship between the number of gate delays per stage and the worse case throughput for a pipeline as a whole is derived. The method then uses this relationship to minimize a pipeline's worse-case throughput by partitioning the NCL combinational circuitry through the addition of asynchronous registers. The method is applied to design a maximum throughput unsigned multiplier, which yields a speedup of 2.25 over the non-pipelined version, while maintaining delay-insensitivity. Third, a technique to mitigate the impact of the NULL cycle is developed. The technique Wher increases the maximum attainable throughput of a NCL system by reducing inherent overheads associated with an integrated data and control path. This technique is applied to a non-pipelined Cbit by 4-bit unsigned multiplier to yield a speedup of 1.61 over the standalone version. Finally, these techniques are applied to design a 72+32x32 multiply and &cumulate (MAC) unit, which outperforms other delay-insensitive/self-timed MACs in the literature. It also performs conditional rounding, scaling, and saturation of the output, whereas the others do not; thus further distinguishing it from the previous work. The methods developed facilitate speed, transistor count, and power tradeoffs using approaches that are readily automatable.
Show less - Date Issued
- 2001
- Identifier
- CFR0001377, ucf:52924
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFR0001377
- Title
- Using argument as a bridge between literacy and science: An intervention study in a science methods course for elementary preservice teachers.
- Creator
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Grysko, Rebeca, Zygouris-Coe, Vassiliki, Gao, Su, Roberts, Sherron, Fang, Zhihui, Bai, Haiyan, University of Central Florida
- Abstract / Description
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The purpose of this study was to investigate the impact of an intervention on teaching science as argument within a science methods course on elementary preservice teachers' (PSTs') (a) understandings of the nature of science (NOS), (b) knowledge about argumentation, (c) complexity of their written explanations, and (d) ability to incorporate components of the framework for teaching science as argument to support students' literacy and science learning. This mixed-methods study utilized an...
Show moreThe purpose of this study was to investigate the impact of an intervention on teaching science as argument within a science methods course on elementary preservice teachers' (PSTs') (a) understandings of the nature of science (NOS), (b) knowledge about argumentation, (c) complexity of their written explanations, and (d) ability to incorporate components of the framework for teaching science as argument to support students' literacy and science learning. This mixed-methods study utilized an embedded quasi-experimental design with a treatment (n = 20) and control group (n = 25). The treatment group instructor, who completed an eight-week professional development course, implemented the intervention protocol across a 12-week period. Throughout the intervention, emphasis was placed on three key components of teaching science as argument (i.e., argument structure, public reasoning, and the language of science). The control group instructor, who did not partake in any professional learning activities, implemented business-as-usual instruction. Results from a repeated measures MANOVA revealed that, although the intervention did not have a significant impact on PSTs' knowledge of argumentation, PSTs who received the intervention did demonstrate a significant increase in their understanding of the NOS and in the complexity of their written explanations, as compared to PSTs who did not receive the intervention. Furthermore, analysis of PSTs' written lesson plans revealed several themes (i.e., opportunities for students to collect and analyze data, use of scaffolds for helping students construct scientific explanations, emphasis on the use of text to support scientific inquiry, and attention to developing students' science vocabulary) consistent with the framework for teaching science as argument. These findings contribute to a growing body of evidence illustrating the effectiveness of intentionally designed teacher preparation experiences for developing PSTs' knowledge, beliefs, and practices for supporting students' engagement in scientific explanation and argument.
Show less - Date Issued
- 2019
- Identifier
- CFE0007643, ucf:52477
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007643
- Title
- Bio-Inspired Visual Servo Control of a Picking Mechanism in an Agricultural Ground Robot.
- Creator
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Defterli, Sinem, Xu, Yunjun, Kauffman, Jeffrey L., Lin, Kuo-Chi, Song, Sang-Eun, Zheng, Qipeng, University of Central Florida
- Abstract / Description
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For a recently constructed disease detection agricultural ground robot, the segregation of unhealthy leaves fromstrawberry plants is a major task of the robot's manipulation subsystem in field operations. In this dissertation, the motion planning of a custom-designedpicking mechanism in the ground robot's subsystem is studied in two sections. First, a set of analytical, suboptimal semi-analyticaland numerical algorithms are studied to solve the inverse kinematics problem of the handling...
Show moreFor a recently constructed disease detection agricultural ground robot, the segregation of unhealthy leaves fromstrawberry plants is a major task of the robot's manipulation subsystem in field operations. In this dissertation, the motion planning of a custom-designedpicking mechanism in the ground robot's subsystem is studied in two sections. First, a set of analytical, suboptimal semi-analyticaland numerical algorithms are studied to solve the inverse kinematics problem of the handling mechanism in firmcircumstances. These premeditated approaches are built on the computation of the joint variables by an identified 3Dposition data of the target leaf only. The outcomes of the three solution algorithms are evaluated in terms of the performanceindexes of energy change and the CPU time cost. The resultant postures of the mechanism for different target pointlocations are observed both in simulations and the hardware experiments with each IK solution. Secondly, after the manipulation task of the mechanism via the proposed inverse kinematicalgorithms is performed, some compensation may be needed due to the sudden and unpredicted deviation of the targetposition under field conditions.For the purpose of finding optimal joint values under certain constraints, a trajectory optimization problem in image-based visual servoing method via the camera-in-handconfiguration is initiated when the end-effector is in the close proximity of the target leaf. In this part of the study, a bio-inspired trajectory optimization problem in image-basedvisual servoing method is constructed based on the mathematical model derived from the prey-predatorrelationships in nature. In this biological phenomenon, the predator constructs its path in a certain subspace whilecatching the prey. When this motion strategy is applied to trajectory optimization problems, it causes a significantreduce in the computation cost since it finds the optimum solution in a certain manifold. The performance of the introducedbio-inspired trajectory optimization in visual servoing is validated with the hardware experiments both in laboratory settings and in fieldconditions.
Show less - Date Issued
- 2018
- Identifier
- CFE0007170, ucf:52247
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007170
- Title
- Examining the use of Background Music to Facilitate Learning.
- Creator
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De La Mora Velasco, Efren, Hirumi, Atsusi, Bai, Haiyan, Boote, David, Sung, Stella, University of Central Florida
- Abstract / Description
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The present work examines the use of background music (BM) to facilitate learning. This dissertation includes three independent, yet interrelated studies that synthesized scholarship to characterize the methods, and BM characteristics that have been manipulated in primary research, to identify trends, patterns and gaps. Then, it integrates findings of experimental studies that reported influences of music on cognitive performance to inform future research and theory. Lastly, this dissertation...
Show moreThe present work examines the use of background music (BM) to facilitate learning. This dissertation includes three independent, yet interrelated studies that synthesized scholarship to characterize the methods, and BM characteristics that have been manipulated in primary research, to identify trends, patterns and gaps. Then, it integrates findings of experimental studies that reported influences of music on cognitive performance to inform future research and theory. Lastly, this dissertation reports a design-based research study aimed at improving an online learning environment with the use of BM to enhance students' motivation, engagement and knowledge retention.
Show less - Date Issued
- 2019
- Identifier
- CFE0007622, ucf:52536
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007622
- Title
- Multi-Modal Interfaces for Sensemaking of Graph-Connected Datasets.
- Creator
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Wehrer, Anthony, Hughes, Charles, Wisniewski, Pamela, Pattanaik, Sumanta, Specht, Chelsea, Lisle, Curtis, University of Central Florida
- Abstract / Description
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The visualization of hypothesized evolutionary processes is often shown through phylogenetic trees. Given evolutionary data presented in one of several widely accepted formats, software exists to render these data into a tree diagram. However, software packages commonly in use by biologists today often do not provide means to dynamically adjust and customize these diagrams for studying new hypothetical relationships, and for illustration and publication purposes. Even where these options are...
Show moreThe visualization of hypothesized evolutionary processes is often shown through phylogenetic trees. Given evolutionary data presented in one of several widely accepted formats, software exists to render these data into a tree diagram. However, software packages commonly in use by biologists today often do not provide means to dynamically adjust and customize these diagrams for studying new hypothetical relationships, and for illustration and publication purposes. Even where these options are available, there can be a lack of intuitiveness and ease-of-use. The goal of our research is, thus, to investigate more natural and effective means of sensemaking of the data with different user input modalities. To this end, we experimented with different input modalities, designing and running a series of prototype studies, ultimately focusing our attention on pen-and-touch. Through several iterations of feedback and revision provided with the help of biology experts and students, we developed a pen-and-touch phylogenetic tree browsing and editing application called PhyloPen. This application expands on the capabilities of existing software with visualization techniques such as overview+detail, linked data views, and new interaction and manipulation techniques using pen-and-touch. To determine its impact on phylogenetic tree sensemaking, we conducted a within-subject comparative summative study against the most comparable and commonly used state-of-the-art mouse-based software system, Mesquite. Conducted with biology majors at the University of Central Florida, each used both software systems on a set number of exercise tasks of the same type. Determining effectiveness by several dependent measures, the results show PhyloPen was significantly better in terms of usefulness, satisfaction, ease-of-learning, ease-of-use, and cognitive load and relatively the same in variation of completion time. These results support an interaction paradigm that is superior to classic mouse-based interaction, which could have the potential to be applied to other communities that employ graph-based representations of their problem domains.
Show less - Date Issued
- 2019
- Identifier
- CFE0007872, ucf:52788
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007872
- Title
- GaN Power Devices: Discerning Application-Specific Challenges and Limitations in HEMTs.
- Creator
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Binder, Andrew, Yuan, Jiann-Shiun, Sundaram, Kalpathy, Roy, Tania, Kapoor, Vikram, Chow, Lee, University of Central Florida
- Abstract / Description
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GaN power devices are typically used in the 600 V market, for high efficiency, high power-density systems. For these devices, the lateral optimization of gate-to-drain, gate, and gate-to-source lengths, as well as gate field-plate length are critical for optimizing breakdown voltage and performance. This work presents a systematic study of lateral scaling optimization for high voltage devices to minimize figure of merit and maximize breakdown voltage. In addition, this optimization is...
Show moreGaN power devices are typically used in the 600 V market, for high efficiency, high power-density systems. For these devices, the lateral optimization of gate-to-drain, gate, and gate-to-source lengths, as well as gate field-plate length are critical for optimizing breakdown voltage and performance. This work presents a systematic study of lateral scaling optimization for high voltage devices to minimize figure of merit and maximize breakdown voltage. In addition, this optimization is extended for low voltage devices ((<) 100 V), presenting results to optimize both lateral features and vertical features. For low voltage design, simulation work suggests that breakdown is more reliant on punch-through as the primary breakdown mechanism rather than on vertical leakage current as is the case with high-voltage devices. A fabrication process flow has been developed for fabricating Schottky-gate, and MIS-HEMT structures at UCF in the CREOL cleanroom. The fabricated devices were designed to validate the simulation work for low voltage GaN devices. The UCF fabrication process is done with a four layer mask, and consists of mesa isolation, ohmic recess etch, an optional gate insulator layer, ohmic metallization, and gate metallization. Following this work, the fabrication process was transferred to the National Nano Device Laboratories (NDL) in Hsinchu, Taiwan, to take advantage of the more advanced facilities there. Following fabrication, a study has been performed on defect induced performance degradation, leading to the observation of a new phenomenon: trap induced negative differential conductance (NDC). Typically NDC is caused by self-heating, however by implementing a substrate bias test in conjunction with pulsed I-V testing, the NDC seen in our fabricated devices has been confirmed to be from buffer traps that are a result of poor channel carrier confinement during the dc operating condition.
Show less - Date Issued
- 2019
- Identifier
- CFE0007885, ucf:52786
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007885
