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Title: A unified approach to dynamic modeling of high switching frequency pwm converters.
Creator: Iannello, Christopher J., Batarseh, Issa, Engineering
Abstract / Description: University of Central Florida College of Engineering Thesis; This dissertation will present the development of a unified approach for dynamic modeling of the PWM and soft-switching power converters. Dynamic modeling of non-linear power converters is very important for the design and stability of their closed loop control. While the use of equivalent circuits is often preferred due to simulation efficiency issues, no unified and widely applicable method for the formulation of these equivalents...
Show moreUniversity of Central Florida College of Engineering Thesis; This dissertation will present the development of a unified approach for dynamic modeling of the PWM and soft-switching power converters. Dynamic modeling of non-linear power converters is very important for the design and stability of their closed loop control. While the use of equivalent circuits is often preferred due to simulation efficiency issues, no unified and widely applicable method for the formulation of these equivalents exists.
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Date Issued: 2001
Identifier: CFR0000833, ucf:52929
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFR0000833

Title: A Framework for Assessing Sustainability Impacts of Truck Routing Strategies.
Creator: Laman, Haluk, Abdel-Aty, Mohamed, Tatari, Omer, Ahmed, Mohamed, University of Central Florida
Abstract / Description: The impact of freight on our transportation system is further accentuated by the fact that trucks consume greater roadway capacity and therefore cause more significant problems including traffic congestion, delay, crashes, air pollution, fuel consumption, and pavement damage. Assessing the actual effects of truck traffic is a growing need to support the ability to safely and efficiently move goods and people in areas where roadway expansion is not the best option. On one hand, trucks need to...
Show moreThe impact of freight on our transportation system is further accentuated by the fact that trucks consume greater roadway capacity and therefore cause more significant problems including traffic congestion, delay, crashes, air pollution, fuel consumption, and pavement damage. Assessing the actual effects of truck traffic is a growing need to support the ability to safely and efficiently move goods and people in areas where roadway expansion is not the best option. On one hand, trucks need to efficiently serve commerce and industry, while at the same time their activities need not contribute to a decline in the quality or public safety. In the current practice, to the best of the authors' knowledge, there is no framework methodology for real-time management of traffic, specifically on truck routes, to reduce travel duration and avoid truck travel delays due to non-recurring congestion (i.e. traffic incidents) and to estimate impacts on traffic flows, economy, and environment. The objective of this study is to develop a truck routing strategy and to quantify its' impacts on travel time, emissions and consequently assess the effects on the economy and environment. In order to estimate non-recurrent congestion based travel delay and fuel consumption by real-time truck routing simulation models, significant corridors with high truck percentages were selected. Furthermore, tailpipe emissions (on-site) due to traveled distance and idling are estimated via MOVES emissions simulator software. Economic Input Output-Life Cycle Assessment Model is utilized to gather fuel consumption related upstream (off-site) emissions. Simulation results of various scenarios indicated that potential annual value of time savings can reach up to $1.67 million per selected corridor. Consistently, fuel costs and emission values are lower, even though extra miles are traveled on the alternative route. In conclusion, our study confirms that truck routing strategies in incident conditions have high economic and environmental impacts.
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Date Issued: 2018
Identifier: CFE0007577, ucf:52570
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007577

Title: Modeling and Transient Simulation of a Fully Integrated Multi-Pressure Heat Recovery Steam Generator Using Siemens T3000.
Creator: McConnell, Jonathan, Das, Tuhin, Chow, Louis, Tian, Tian, University of Central Florida
Abstract / Description: The focus of this research is on the transient thermodynamic properties and dynamic behavior of a Heat Recovery Steam Generator (HRSG). An HRSG is a crossflow heat exchanger designed for the extraction of energy from the hot exhaust gas of a traditional power plant through boiling induced phase change. Superheated steam is sent through a turbine to generate additional power, raising the overall efficiency of a power plant. The addition of renewable energies and the evolution of smart grids...
Show moreThe focus of this research is on the transient thermodynamic properties and dynamic behavior of a Heat Recovery Steam Generator (HRSG). An HRSG is a crossflow heat exchanger designed for the extraction of energy from the hot exhaust gas of a traditional power plant through boiling induced phase change. Superheated steam is sent through a turbine to generate additional power, raising the overall efficiency of a power plant. The addition of renewable energies and the evolution of smart grids have brought forth a necessity to gain a comprehensive understanding of transient behavior within an HRSG in order to efficiently manage the power output of traditional plants. Model-based techniques that can simulate a wide range of operating conditions can be valuable and insightful. For this reason, a multi-physics model of an HRSG has been developed in Siemens T3000 plant monitoring software. The layout and conditions of a reference HRSG have been provided by Siemens Energy Inc. along with validation data for behavioral comparison. The HRSG selected is a three pressure stage HRSG. Simultaneous simulation of these three pressure systems and their interactions has been achieved. A potential for real time execution was demonstrated. An HRSG is built of three major subsystems, namely economizers, boilers, and superheaters. A lumped control volume approach has been implemented to efficiently model the energy and mass balances of medium within each subsystem. In this effort, considering the goal of real time simulation, special attention was paid to balance computational burden with numerical accuracy.A major focus of this research has been accurately modeling the complexities of phase change within a boiler subsystem. A switching mechanism has been developed to numerically model the dynamic heating and evaporation of boiler liquid. To increase robustness of the model to numerical fluctuations and perturbations, bidirectional flow comprising of boiling and condensation was modeled with the switching mechanism. This numerically robust model shows good agreement with the validation data provided by Siemens.
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Date Issued: 2019
Identifier: CFE0007683, ucf:52459
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007683

Title: Modeling the innovation ecosystem and development of a dynamic innovation index.
Creator: Schoen, Henriette, Karwowski, Waldemar, Hoekstra, Robert, Shumaker, Randall, Akbas, Mustafa, University of Central Florida
Abstract / Description: The topic of innovation currently generates a tremendous amount of interest around the world. Innovation is considered an essential part of the solution to creating more jobs and improving the socio-economic conditions of many countries around the globe. Innovation comes about through the existence of many interrelated solutions to socio-economic problems in an extensively interconnected network, which create value for each other. Such a complex creativity and innovation value-creating...
Show moreThe topic of innovation currently generates a tremendous amount of interest around the world. Innovation is considered an essential part of the solution to creating more jobs and improving the socio-economic conditions of many countries around the globe. Innovation comes about through the existence of many interrelated solutions to socio-economic problems in an extensively interconnected network, which create value for each other. Such a complex creativity and innovation value-creating network is here called an Innovation Ecosystem (IE). The main objective of this dissertation research is to improve the current understanding of the IE by developing a simulation model that uses a broad set of relevant static and dynamic variables and incorporates the principles of system dynamics (SD). The proposed model, which is named the IECO-model is based on the relationships between 91 variables and the combined influences of the 43 parameters. Available data for 32 countries, representing a full span of GDP worldwide, was used to study the level of innovation in each of these countries. The result of the developed IECO-model is a novel ranking of the level of innovation through a dynamic innovation index, called the DII. The DII is a new tool to evaluate the innovation and entrepreneurship level of a given country in the context of the global economy. The most significant differentiator from other existing indices of innovation is that the DII is focusing more on the entrepreneurship qualities in 19 of the 43 parameters by looking at cultural values and belief systems, the social context, existing entrepreneurial culture, innovation attitudes, and mentality of each of the considered countries. According to DII-based ranking, the ten most innovative countries in the world are 1. Switzerland, 2. USA, 3. Finland, 4. Netherlands, 5. Iceland, 6. Sweden, 7. Germany, 8. Denmark, 9. The United Kingdom, and 10. Austria.
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Date Issued: 2018
Identifier: CFE0007586, ucf:52537
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007586

Title: Influence of Selected Factors on a Counselor's Attention Level to and Counseling Performance with a Virtual Human in a Virtual Counseling Session.
Creator: Hart, John, Proctor, Michael, Jentsch, Florian, Li, Daoji, Morie, Jacquelyn, University of Central Florida
Abstract / Description: Virtual humans serve as role-players in social skills training environments simulating situational face-to-face conversations. Previous research indicates that virtual humans in instructional roles can increase a learner's engagement and motivation towards the training. Left unaddressed is if the learner is looking at the virtual human as one would in a human-to-human, face-to-face interaction. Using a modified version of the Emergent Leader Immersive Training Environment (ELITE-Lite), this...
Show moreVirtual humans serve as role-players in social skills training environments simulating situational face-to-face conversations. Previous research indicates that virtual humans in instructional roles can increase a learner's engagement and motivation towards the training. Left unaddressed is if the learner is looking at the virtual human as one would in a human-to-human, face-to-face interaction. Using a modified version of the Emergent Leader Immersive Training Environment (ELITE-Lite), this study tracks visual attention and other behavior of 120 counselor trainees counseling a virtual human role-playing counselee. Specific study elements include: (1) the counselor's level of visual attention toward the virtual counselee; (2) how changes to the counselor's viewpoint may influence the counselor's visual focus; and (3) how levels of the virtual human's behavior may influence the counselor's visual focus. Secondary considerations include aspects of learner performance, acceptance of the virtual human, and impacts of age and rank. Result highlights indicate that counselor visual attentional behavior could be separated into two phases: when the virtual human was speaking and when not speaking. When the virtual human is speaking, the counselor's primary visual attention is on the counselee, but is also split toward pre-scripted responses required for the training session. During the non-speaking phase, the counselor's visual focus was on pre-scripted responses required for training. Some of the other findings included that participants did not consider this to be like a conversation with a human, but they indicated acceptance of the virtual human as a partner with the training environment and they considered the simulation to be a useful experience. Additionally, the research indicates behavior may differ due to age or rank. Future study and design considerations for enhancements to social skills training environments are provided.
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Date Issued: 2018
Identifier: CFE0007571, ucf:52572
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007571

Title: Design and Optimization of a Wave Energy Harvester Utilizing a Flywheel Energy Storage System.
Creator: Helkin, Steven, Lin, Kuo-Chi, Gordon, Ali, Raghavan, Seetha, University of Central Florida
Abstract / Description: This thesis details the design and optimization of a buoy used to collect renewable energy from ocean waves. The proposed buoy is a point absorber(-)a device that transforms the kinetic energy of the vertical motion of surface waves into electrical energy. The focus of the research is on the mechanical system used to collect the energy, and methods to improve it for eventual use in an actual wave energy harvester. A flywheel energy storage system was utilized in order to provide an improved...
Show moreThis thesis details the design and optimization of a buoy used to collect renewable energy from ocean waves. The proposed buoy is a point absorber(-)a device that transforms the kinetic energy of the vertical motion of surface waves into electrical energy. The focus of the research is on the mechanical system used to collect the energy, and methods to improve it for eventual use in an actual wave energy harvester. A flywheel energy storage system was utilized in order to provide an improved power output from the system, even with the intermittent input of force exerted by ocean waves. A series of laboratory prototypes were developed to analyze parameters that are important to the success of the point absorb mechanical system. By introducing a velocity-based load control scheme in conjunction with flywheel energy storage, it was seen that the average power output by the prototype was increased. The generator load is controlled via a relay switch that removes electrical resistance from the generator(-)this sacrifices time during which power is drawn from the system, but also allows the buoy to move with less resistance. A simulation model was developed in order to analyze the theoretical wave absorber system and optimize the velocity threshold parameters used in the load control. Results indicate that the power output by the system can be substantially improved through the use of a flywheel energy storage control scheme that engages and disengages the electrical load based on the rotational velocity of the flywheel system. The results of the optimization are given for varying-sized generator systems input into the simulation in order to observe the associated trends.
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Date Issued: 2011
Identifier: CFE0004118, ucf:49113
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004118

Title: "Design and Simulation of CMOS RF Active Mixers".
Creator: Gibson, Allen, Yuan, Jiann-Shiun, Wei, Lei, Sundaram, Kalpathy, University of Central Florida
Abstract / Description: This paper introduces a component of the Radio Frequency transceiver called the mixer. The mixer is a critical component in the RF systems, because of its ability for frequency conversion. This passage focuses on the design analysis and simulation of multiple topologies for the active down-conversion mixer. This mixer is characterized by its important design properties which consist of conversion gain, linearity, noise figure, and port isolation. The topologies that are given in this passage...
Show moreThis paper introduces a component of the Radio Frequency transceiver called the mixer. The mixer is a critical component in the RF systems, because of its ability for frequency conversion. This passage focuses on the design analysis and simulation of multiple topologies for the active down-conversion mixer. This mixer is characterized by its important design properties which consist of conversion gain, linearity, noise figure, and port isolation. The topologies that are given in this passage range from the most commonly known mixer design, to implemented design techniques that are used to increase the mixers important design properties as the demand of CMOS technology and the overall RF system rises. All mixer topologies were designed and simulated using TSMC 0.18 (&)#181;m CMOS technology in Advanced Design Systems, a simulator used specifically for RF designs.
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Date Issued: 2011
Identifier: CFE0004112, ucf:49086
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004112

Title: First Principles Studies of Pattern Formations and Reactions on Catalyst Surfaces.
Creator: Le, Duy, Rahman, Talat, Roldan Cuenya, Beatriz, Schelling, Patrick, Sohn, Yongho, University of Central Florida
Abstract / Description: This dissertation undertakes theoretical research into the adsorption, pattern formation, and reactions of atoms, molecules, and layered materials on catalyst surfaces. These investigations are carried out from first-principles calculations of electronic and geometric structures using density functional theory (DFT) for predictions and simulations at the atomic scale. The results should be useful for further study of the catalytic activities of materials and for engineering functional...
Show moreThis dissertation undertakes theoretical research into the adsorption, pattern formation, and reactions of atoms, molecules, and layered materials on catalyst surfaces. These investigations are carried out from first-principles calculations of electronic and geometric structures using density functional theory (DFT) for predictions and simulations at the atomic scale. The results should be useful for further study of the catalytic activities of materials and for engineering functional nanostructures.The first part of the dissertation focuses on systematic first-principles simulations of the energetic pathways of CO oxidation on the Cu2O(100) surface. These simulations show CO to oxidize spontaneously on the O-terminated Cu2O(100) surface by consuming surface oxygen atoms. The O-vacancy on Cu2O(100) then is subsequently healed by dissociative adsorption of atmospheric O2 molecules.The second part discusses the pattern formation of hydrogen on two and three layers of Co film grown on the Cu(111) surface. It is found that increasing the pressure of H2 changes the hydrogen structure from 2H-(2 x 2) to H-p(1 x 1) through an intermediate structure of 6H-(3 x 3).The third part compares the results of different ways of introducing van der Waals (vdW) interactions into DFT simulations of the adsorption and pattern formation of various molecules on certain substrates. Examinations of the physisorption of five nucleobases on graphene and of n-alkane on Pt(111) demonstrate the importance of taking vdW interactions into account, and of doing so in a way that is best suited to the particular system in question. More importantly, as the adsorption of 1,4 diaminebenzene molecules on Au(111) shows inclusion of vdW interactions is crucial for accurate simulation of the pattern formation.The final part carries out first-principles calculations of the geometric and electronic structure of the Moire pattern of a single layer of Molybdenum disulfide (MoS2) on Cu(111). The results reveal three possible stacking types. They also demonstrate that the MoS2 layer to be chemisorbed, albeit weakly, and that, while Cu surface atoms are vertically disordered, the layer itself is not strongly buckled.
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Date Issued: 2012
Identifier: CFE0004224, ucf:48991
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004224

Title: EXPERIMENTAL AND CFD INVESTIGATIONS OF LIFTED TRIBRACHIAL FLAMES.
Creator: li, zhiliang, Chen, Ruey-Hung, University of Central Florida
Abstract / Description: Experimental measurements of the lift-off velocity and lift-off height, and numerical simulations were conducted on the liftoff and stabilization phenomena of laminar jet diffusion flames of inert-diluted C3H8 and CH4 fuels. Both non-reacting and reacting jets were investigated, including effects of multi-component diffusivities and heat release (buoyancy and gas expansion). The role of Schmidt number for non-reacting jets was investigated, with no conclusive Schmidt number criterion for...
Show moreExperimental measurements of the lift-off velocity and lift-off height, and numerical simulations were conducted on the liftoff and stabilization phenomena of laminar jet diffusion flames of inert-diluted C3H8 and CH4 fuels. Both non-reacting and reacting jets were investigated, including effects of multi-component diffusivities and heat release (buoyancy and gas expansion). The role of Schmidt number for non-reacting jets was investigated, with no conclusive Schmidt number criterion for liftoff previously known in similarity solutions. The cold-flow simulation for He-diluted CH4 fuel does not predict flame liftoff; however, adding heat release reaction leads to the prediction of liftoff, which is consistent with experimental observations. Including reaction was also found to improve liftoff height prediction for C3H8 flames, with the flame base location differing from that in the similarity solution - the intersection of the stoichiometric and iso-velocity contours is not necessary for flame stabilization (and thus lift-off). Possible mechanisms other than that proposed for similarity solution may better help to explain the stabilization and liftoff phenomena. The stretch rate at a wide range of isotherms near the base of the lifted tribrachial flame were also quantitatively plotted and analyzed.
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Date Issued: 2010
Identifier: CFE0003135, ucf:48621
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003135

Title: TESTING THE IMPACT OF TRAINING WITH SIMULATED SCENARIOS FOR INFORMATION SECURITY AWARENESS ON VIRTUAL COMMUNITY OF PRACTICE MEMBERS.
Creator: Tidwell, Craig, Reilly, Charles, University of Central Florida
Abstract / Description: Information security has become a major challenge for all private and public organizations. The protection of proprietary and secret data and the proper awareness of what is entailed in protecting this data are necessary in all organizations. This treatise examines how simulation and training would influence information security awareness over time in virtual communities of practice under a variety of security threats. The hypothesis of the study was that security-trained members of a virtual...
Show moreInformation security has become a major challenge for all private and public organizations. The protection of proprietary and secret data and the proper awareness of what is entailed in protecting this data are necessary in all organizations. This treatise examines how simulation and training would influence information security awareness over time in virtual communities of practice under a variety of security threats. The hypothesis of the study was that security-trained members of a virtual community of practice would respond significantly better to routine security processes and attempts to breach security or to violate the security policy of their organization or of their virtual community of practice. Deterrence theory was used as the grounded theory and integrated in the information security awareness training with simulated scenarios. The study provided training with simulated scenarios and then tested the users of a virtual community of practice over an approximately twelve-week period to see if the planned security awareness training with simulated security problem scenarios would be effective in improving their responses to the follow-up tests. The research subjects were divided into four groups, the experimental group and three control groups. The experimental group received all of the training and testing events throughout the twelve-week period. The three control groups received various portions of the training and testing. The data from all of the tests were analyzed using the Kruskal-Wallis ranked order test, and it was determined that there was no significant difference between the groups at the end of the data collection. Even though the null hypothesis, which stated that there would be no difference between the groups scores on the information security awareness tests, was not rejected, the groups that received the initial training with the simulated scenarios did perform slightly better from the pre-training test to the post-training test when compared with the control group that did not receive the initial training. More research is suggested to determine how information security awareness training with simulated scenarios and follow-up testing can be used to improve and sustain the security practices of members of virtual communities of practice. Specifically, additional research could include: comparing the effect of training with the simulated scenarios and with training that would not use the simulated security scenarios; the potential benefits of using adaptive and intelligent training to focus on the individual subjects' weaknesses and strengths; the length of the training with simulated scenarios events, the time between each training event, and the overall length of the training; the demographics of the groups used in the training, and how different user characteristics impact the efficacy of the training with simulated scenarios and testing; and lastly examining how increasing the fidelity of the simulated scenarios might impact the results of the follow-up tests.
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Date Issued: 2011
Identifier: CFE0003566, ucf:48923
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003566

Title: TEXT VERSUS VERBAL REAL-TIME FEEDBACK DURING SIMULATION-BASED TRAINING OF HIGHER-ORDER COGNITIVE SKILLS.
Creator: Fiorella, Christopher, Shumaker, Randall, University of Central Florida
Abstract / Description: A crucial component of instructional design for simulation-based training systems involves optimizing the presentation of complex material in order to maximize knowledge acquisition and application. One approach toward facilitating the learning of this complex information is to instantiate instructional strategies within the training systems themselves. However, there are few established guidelines in place which are meant specifically for real-time guidance strategies within simulation-based...
Show moreA crucial component of instructional design for simulation-based training systems involves optimizing the presentation of complex material in order to maximize knowledge acquisition and application. One approach toward facilitating the learning of this complex information is to instantiate instructional strategies within the training systems themselves. However, there are few established guidelines in place which are meant specifically for real-time guidance strategies within simulation-based environments. Consequently, this study aims to apply findings from the literature on instructional information presentation to drive decisions for how to most effectively provide real-time feedback during training of simulated decision-making tasks. Research has shown that presenting text information in an auditory mode during direct instruction of operational tasks enhances learning and reduces the probability of learners experiencing cognitive overload. Similar effects have been found regarding the presentation modality of feedback during operational tasks. In the current study, this principle was extended by comparing text versus verbal real-time feedback presentation during learning of higher-level cognitive skills in a virtual environment. Participants were instructed on how to perform a simulated decision-making task, while receiving text, verbal or no instructional feedback in real-time, based on their performance. Participants then completed an assessment scenario in which no feedback was provided to any group. It was hypothesized that a linear relationship would exist across each of the three conditions, with the verbal group making the best decisions, followed by the text group, and then by the control group. Additionally, reduced cognitive load was expected throughout the instructional process for those receiving verbal feedback prompts compared to those receiving text prompts and the control. Analyses revealed several significant linear trends across conditions regarding measures of knowledge acquisition and application. The results provide support for the hypothesis that verbal real-time feedback is more effective than text during training of primarily visual tasks for the acquisition of higher-order cognitive skills such as decision making. There were no significant linear trends regarding the amount of cognitive load subjectively reported during training and assessment. The results of this study indicate that instructional systems intended to train primarily visual tasks should present real-time feedback in verbal rather than text form.
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Date Issued: 2010
Identifier: CFE0003555, ucf:48915
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003555

Title: Coaching in an Interactive Virtual Reality to Increase Fidelity of Implementation of Discrete Trial Teaching.
Creator: Vince Garland, Krista, Wienke, Wilfred, Pearl, Cynthia, Dieker, Lisa, Vasquez, Eleazar, Sundeen, Todd, University of Central Florida
Abstract / Description: In teacher preparation, more effective pathways and practices are needed for preparing, placing, and supporting beginning teachers and principals (Darling-Hammond, 2010; U.S. Department of Education, 2009b). A common issue in the field of special education is the lack of skill transfer from one setting to another (Dieker, Hynes, Hughes, (&) Smith, 2008). It has been posited that (")practicing up(") is not ethical in that novice teachers must attempt to teach with a limited knowledge of...
Show moreIn teacher preparation, more effective pathways and practices are needed for preparing, placing, and supporting beginning teachers and principals (Darling-Hammond, 2010; U.S. Department of Education, 2009b). A common issue in the field of special education is the lack of skill transfer from one setting to another (Dieker, Hynes, Hughes, (&) Smith, 2008). It has been posited that (")practicing up(") is not ethical in that novice teachers must attempt to teach with a limited knowledge of appropriate pedagogy and skill (Dieker et al., 2008). The new challenge becomes finding an effective mechanism that provides essential learning experiences and opportunities to refine teaching techniques to the highest standards of fidelity in a safely controlled and coordinated environment (Odom, 2009).Perhaps because of the ethical concerns in honing teacher skills on actual children, and despite the strong demand for professionals who are trained in discrete trial teaching (DTT), few studies have been published on training methodologies and fidelity of implementation (Fazzio, Martin, Arnal, (&) Yu, 2009). The training of teachers to implement evidence-based interventions such as DTT with fidelity while they are working with students with ASD cannot be over-emphasized in a teacher preparation program (Scheuermann, Webber, Boutot, (&) Goodwin, 2003; Simpson, 2004; 2005). The researcher utilized the TLE TeachLivE simulation classroom laboratory at the University of Central Florida as a mechanism to infuse cutting-edge technology and learning activities within program/project coursework. The TLE TeachLivE virtual classroom serves as a venue for pre-service and practicing teachers to safely gain proficiency and enhance fidelity of implementation of evidence-based practices. Participants experienced an immersive, real-time environment that featured interactions with Austin, an avatar that portrayed a student with autism. A trained interactor remotely controlled the behavior and responses of the avatar with which teachers engaged for practice sessions consisting of ten discrete trials. Between sessions, participants received individualized clinical coaching (ICC) on their performance. Upon termination of the intervention, two generalization probes were conducted to measure retention of fidelity over time within actual classroom settings. Results indicated that all five participants strongly benefited from learning DTT with ICC in the TLE TeachLivE learning platform.Across participants, the overall mean gain in fidelity from baseline phase (14%) to intervention phase (80%) was 66%. The fidelity means of participants in the generalization phase held to 90%, thus supporting the use of virtual environments for teacher preparation. Mean time among participants to attain higher than mastery level performance of 90% in intervention was 1.25 hours. This resulted in shorter training times than previously researched training programs (Arnal et al., 2007; Fazzio et al., 2009; Leblanc, (&) Luiselli, 2005; Thiessen et al., 2009). This investigation endeavored to reduce the potential of diminished pupil learning gains as a necessary consequence when honing skills in the appropriate delivery of instruction of discrete trial teaching.
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Date Issued: 2012
Identifier: CFE0004450, ucf:49327
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004450

Title: Simulation-Based Cognitive Workload Modeling and Evaluation of Adaptive Automation Invoking and Revoking Strategies.
Creator: Rusnock, Christina, Geiger, Christopher, Karwowski, Waldemar, Xanthopoulos, Petros, Reinerman, Lauren, University of Central Florida
Abstract / Description: In human-computer systems, such as supervisory control systems, large volumes of incoming and complex information can degrade overall system performance. Strategically integrating automation to offload tasks from the operator has been shown to increase not only human performance but also operator efficiency and safety. However, increased automation allows for increased task complexity, which can lead to high cognitive workload and degradation of situational awareness. Adaptive automation is...
Show moreIn human-computer systems, such as supervisory control systems, large volumes of incoming and complex information can degrade overall system performance. Strategically integrating automation to offload tasks from the operator has been shown to increase not only human performance but also operator efficiency and safety. However, increased automation allows for increased task complexity, which can lead to high cognitive workload and degradation of situational awareness. Adaptive automation is one potential solution to resolve these issues, while maintaining the benefits of traditional automation. Adaptive automation occurs dynamically, with the quantity of automated tasks changing in real-time to meet performance or workload goals. While numerous studies evaluate the relative performance of manual and adaptive systems, little attention has focused on the implications of selecting particular invoking or revoking strategies for adaptive automation. Thus, evaluations of adaptive systems tend to focus on the relative performance among multiple systems rather than the relative performance within a system.This study takes an intra-system approach specifically evaluating the relationship between cognitive workload and situational awareness that occurs when selecting a particular invoking-revoking strategy for an adaptive system. The case scenario is a human supervisory control situation that involves a system operator who receives and interprets intelligence outputs from multiple unmanned assets, and then identifies and reports potential threats and changes in the environment. In order to investigate this relationship between workload and situational awareness, discrete event simulation (DES) is used. DES is a standard technique in the analysis of systems, and the advantage of using DES to explore this relationship is that it can represent a human-computer system as the state of the system evolves over time. Furthermore, and most importantly, a well-designed DES model can represent the human operators, the tasks to be performed, and the cognitive demands placed on the operators. In addition to evaluating the cognitive workload to situational awareness tradeoff, this research demonstrates that DES can quite effectively model and predict human cognitive workload, specifically for system evaluation.This research finds that the predicted workload of the DES models highly correlates with well-established subjective measures and is more predictive of cognitive workload than numerous physiological measures. This research then uses the validated DES models to explore and predict the cognitive workload impacts of adaptive automation through various invoking and revoking strategies. The study provides insights into the workload-situational awareness tradeoffs that occur when selecting particular invoking and revoking strategies. First, in order to establish an appropriate target workload range, it is necessary to account for both performance goals and the portion of the workload-performance curve for the task in question. Second, establishing an invoking threshold may require a tradeoff between workload and situational awareness, which is influenced by the task's location on the workload-situational awareness continuum. Finally, this study finds that revoking strategies differ in their ability to achieve workload and situational awareness goals. For the case scenario examined, revoking strategies based on duration are best suited to improve workload, while revoking strategies based on revoking thresholds are better for maintaining situational awareness.
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Date Issued: 2013
Identifier: CFE0004927, ucf:49607
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004927

Title: Harmony: An Architecture for Network Centric Heterogeneous Terrain Database Re-Generation.
Creator: Graniela Ortiz, Benito, Proctor, Michael, Gonzalez, Avelino, Wiegand, Rudolf, Goldiez, Brian, Cox, Robert, University of Central Florida
Abstract / Description: This research investigated an alternative modeling and simulation terrain database generation paradigm that rapidly harmonizes changes target formats throughout a distributed simulation system while accommodating bandwidth and processing time limitations. This dissertation proposes a (")distributed partial bi-directional terrain database re-generation(") paradigm, which envisions network based terrain database updates between reliable partners. The approach is very attractive as it reduces...
Show moreThis research investigated an alternative modeling and simulation terrain database generation paradigm that rapidly harmonizes changes target formats throughout a distributed simulation system while accommodating bandwidth and processing time limitations. This dissertation proposes a (")distributed partial bi-directional terrain database re-generation(") paradigm, which envisions network based terrain database updates between reliable partners. The approach is very attractive as it reduces the amount of processing and bandwidth required to distribute locally emergent changes throughout a distributed system by only updating the affected target format data elements. In the prototype theoretical architecture that implements the approach, agent theory and ontologies are used to interpret data changes in external target formats and implement the necessary transformations on a server internal terrain database generation system. These changes are then distributed to clients to achieve consistency between all correlated representations. Experimental findings with the prototype suggests smaller network utilization and processing times than conventional terrain database generation will experience while maintaining correlated heterogeneous terrain database representations overtime. This Bi-Directional Ontology-driven TDB Re-Generation Architecture has the potential to revolutionize the traditional terrain database generation pipeline paradigm.
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Date Issued: 2011
Identifier: CFE0004475, ucf:49315
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004475

Title: OPTIMIZED MARKET INTRODUCTION OF LARGE CAPITAL PRODUCTS WITH LONG DEVELOPMENT AND LEARNING CYCLES.
Creator: Lembcke, Antje, Malone, Linda, University of Central Florida
Abstract / Description: Any product sold is expected to be reliable and available when the customer wants to operate it. Companies that produce large capital products (LCP), such as rockets, satellites, or large gas turbines to generate electrical energy, tend to shy away from extending their testing and validation method above the requirements by law, mainly due to the very high costs of each additional test and the uncertain return on investment. This research shows that todayÃ‚Â's state of...
Show moreAny product sold is expected to be reliable and available when the customer wants to operate it. Companies that produce large capital products (LCP), such as rockets, satellites, or large gas turbines to generate electrical energy, tend to shy away from extending their testing and validation method above the requirements by law, mainly due to the very high costs of each additional test and the uncertain return on investment. This research shows that todayÃ‚Â's state of the art validation methods for LCP, required by law, or suggested in literature, and adapted by these industries, are not capable of capturing all significant failure modes (or even enough failure modes), with the consequence that the subsequently sold commercial products will still experience failures with significant effects on product reliability, and subsequently on the companiesÃ‚Â' bottom line earnings projections. The research determines the type of data (significant variables) necessary to correlate a companyÃ‚Â's validation policy to product failures after commercialization, and predicts the financial impact of the current validation policy on the companyÃ‚Â's profitability. A systems dynamics model to assess a company's testing policy is developed and an optimized product validation plan is suggested, and its impact on a companyÃ‚Â's profitability is demonstrated through simulation. A generic methodology is derived and its viability is illustrated using a specific product and a dynamic model developed with data available to the researcher. The generic method can be applied by any company to develop its own model for optimizing product reliability prior to market introduction.
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Date Issued: 2010
Identifier: CFE0003413, ucf:48404
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003413

Title: A MODEL OF FLOW AND PLAY IN GAME-BASED LEARNING: THE IMPACT OF GAME CHARACTERISTICS, PLAYER TRAITS, AND PLAYER STATES.
Creator: Pavlas, Davin, Salas, Eduardo, University of Central Florida
Abstract / Description: In this dissertation, the relationship between flow state, serious games, and learning was examined. Serious games, which are games that convey something other than enjoyment (e.g., learning), are increasingly popular platforms for research, training, and advertisement. The elements that make serious games useful to researchers, trainers, and practitioners are closely linked to those that make up the positive psychology construct of flow state. Flow state describes an optimum experience that...
Show moreIn this dissertation, the relationship between flow state, serious games, and learning was examined. Serious games, which are games that convey something other than enjoyment (e.g., learning), are increasingly popular platforms for research, training, and advertisement. The elements that make serious games useful to researchers, trainers, and practitioners are closely linked to those that make up the positive psychology construct of flow state. Flow state describes an optimum experience that is encountered when a variety of factors are met, and is characterized by high focus, engagement, motivation, and immersion. While flow state is often discussed in the serious games literature, in-depth empirical examinations of flow state remain elusive. In this dissertation I addressed this need by conducting a thorough literature review of flow, serious games, and game-based learning in order to propose a new model of flow in games. Two studies were conducted in support of this model. The first experiment consisted of the creation and validation of a play experience scale. Based on the data from 203 Study 1 participants, the Play Experience Scale was validated for use with video games. The 14-item version of the Play Experience Scale was composed of the components of freedom, lack of extrinsic motivation, autotelic experience, and direct assessment of play. The scale was reliable, with a calculated alpha of .86. In the second study, the newly developed scale was used alongside an immune system serious game to examine the impact of play, in-game performance, and emotional experience on flow in games. In an effort to provide a more symmetrical version of the scale, two items were added to the scale, resulting in a 16-item revision. Based on the empirical results obtained from Study 2Ã‚Â's 77 participants, the proposed model of flow in games was revised slightly. Though Study 2 only examined a subset of the overall model of flow in games, the evidence suggested the model was a good theoretical match. Further, the two added items of the Play Experience Scale were valid, providing a final 16-item version of the scale. Play and in-game performance were key predictors of game-based learning. Additionally, play, video game self-efficacy, and emotional experience exhibited a reciprocal relationship with flow state. Implications for serious game development, scientific research into games and learning, and industry testing of game playability were provided. Following these implications, conclusions were presented alongside suggestions for further research.
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Date Issued: 2010
Identifier: CFE0003425, ucf:48394
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003425

Title: EFFECTIVE TIMING OF FEEDBACK DURING SCENARIO BASED TEAM TRAINING WITHIN A SIMULATED ENVIRONMENT.
Creator: Astwood, Randolph, Smith-Jentsch, Kimberly, University of Central Florida
Abstract / Description: Scenario based training (SBT) allows organizations to train the competencies necessary for effective performance in an environment that replicates critical aspects of the transfer or operational setting. One of the most salient training features that can be delivered during SBT is feedback. Task feedback may be provided to trainees either during a training scenario (immediately following actions) or between training scenarios (after action review). However, little is known regarding the...
Show moreScenario based training (SBT) allows organizations to train the competencies necessary for effective performance in an environment that replicates critical aspects of the transfer or operational setting. One of the most salient training features that can be delivered during SBT is feedback. Task feedback may be provided to trainees either during a training scenario (immediately following actions) or between training scenarios (after action review). However, little is known regarding the effects of immediate versus delayed feedback given to teams. Prior research on training individuals suggests that immediate feedback improves performance as assessed immediately after training (acquisition performance), however delayed feedback improves performance after time has passed (retention performance). Moreover, several individual training studies have found that trainee goal orientation moderates the influence of instructional features such as goal difficulty and content organization. I hypothesized that team member goal orientation would also moderate the influence of feedback timing on team performance. Three facets of goal orientation were assessed. Learning goal orientation refers to the extent to which individuals strive towards the mastery of skills for the sake of continuous improvement. Prove goal orientation refers to the extent to which individuals strive to demonstrate their own competence to others. Finally, avoid goal orientation refers to the extent to which individuals seek to avoid demonstrating their incompetence to others. Participants were 160 undergraduate psychology students assigned to 80 two-person teams. These teams were trained and tested using a simulated military task called the Forward Observer Personal Computer-based Simulator. Teams received 36 minutes of training prior to performing a skill acquisition test on day one of the experiment. One week later teams returned to perform a skill retention test. Teams were randomly assigned to receive immediate feedback during their team training scenarios or delayed feedback following each training scenario. Results indicated that the timing of feedback had no impact on acquisition performance. As predicted, however, teams that had received delayed feedback outperformed those that had received immediate feedback on the retention test. Moreover, the positive impact of delayed feedback on retention performance was greatest for teams that scored higher on a measure of state learning goal orientation on the day of their training. This interaction was mediated by the team's perception of the instrumentality of the feedback provided to them. Theoretical and practical implications, as well as, limitations and directions for future research are discussed.
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Date Issued: 2009
Identifier: CFE0002672, ucf:48244
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002672

Title: EFFECTS OF 3D STEREOSCOPY, VISUO-SPATIAL WORKING MEMORY, AND PERCEPTIONS OF SIMULATION EXPERIENCE ON THE MEMORIZATION OF CONFUSABLE OBJECTS.
Creator: Keebler, Joseph, Jentsch, Florian, University of Central Florida
Abstract / Description: This dissertation investigated the impact of active stereoscopic 3-dimensional (3D) imagery equipment and individual differences in visuo-spatial working memory (VSWM) capacity on retention of a set of similar, novel objects (i.e., armored military vehicles). Seventy-one participants were assessed on their visuo-spatial working memory using the Visual Patterns Test (Della Sala, Gray, Baddeley, & Wilson, 1997). They were then assigned to one of four different conditions (3D high VSWM, 3D low...
Show moreThis dissertation investigated the impact of active stereoscopic 3-dimensional (3D) imagery equipment and individual differences in visuo-spatial working memory (VSWM) capacity on retention of a set of similar, novel objects (i.e., armored military vehicles). Seventy-one participants were assessed on their visuo-spatial working memory using the Visual Patterns Test (Della Sala, Gray, Baddeley, & Wilson, 1997). They were then assigned to one of four different conditions (3D high VSWM, 3D low VSWM, 2D high VSWM, 2D low VSWM) based upon their visuo-spatial working memory. Participants were then trained to identify military vehicles using a simulation that presented the training stimuli in one of two dimensionalities, i.e. two dimensional (2D) or active stereoscopic three-dimensional (3D). Testing consisted of a vehicle memory training assessment, which challenged participants to choose the correct components of each vehicle immediately after studying; a measure of retention for military vehicles which asked participants to categorize the alliance and identify previously studied vehicles; and a transfer measure using video footage of actual military vehicles. The latter measures depicted military vehicles in an array of combat situations, and participants were asked to decide on whether or not to shoot each vehicle, as well as identify the vehicles. Testing occurred immediately after training. The moderating, as well as main effects, of VSWM were assessed. The mediating/moderating effects of several experiential factors were measured as well, including: immersion, presence, engagement, flow state, and technology acceptance. Findings indicate that perceptions of the simulation experience and VSWM are strong positive predictors of performance, while 3D was not predictive, and in some instances, significantly worse than the 2D condition. These findings indicate that individual differences in visual memory and user experiences during the SBT both are predictive factors in memory tasks for confusable objects. The SBT designed in this study also led to robust prediction of training outcomes on the final transfer task.
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Date Issued: 2011
Identifier: CFE0003939, ucf:48702
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003939

Title: SIMULATION FOR COMMERCIAL DRIVER LICENSE THIRD PARTY TESTER TESTING.
Creator: Truong, Henry, Lin, Kurt, University of Central Florida
Abstract / Description: The advance of technology is thought to help ease the myriad tasks that are usually involved in operating equipment. Training and testing in modern times have been replacing with simulation technologies that mimic the actual live operations and testing. Many successful stories of flight simulation come from military fighter aircraft and commercial pilot programs. The possibilities of safety in saving lives, economic incentive in reducing the operational cost and reducing the carbon footprint...
Show moreThe advance of technology is thought to help ease the myriad tasks that are usually involved in operating equipment. Training and testing in modern times have been replacing with simulation technologies that mimic the actual live operations and testing. Many successful stories of flight simulation come from military fighter aircraft and commercial pilot programs. The possibilities of safety in saving lives, economic incentive in reducing the operational cost and reducing the carbon footprint via simulation makes simulation worth looking into. These considerations quickly boosted the transfer from live training operations to virtual and simulation, as were easily adopted in the history of flight training and testing. Although, there has been a lack of application, the benefits of the computer based simulation as a modeling and simulation (M&S) tool can be applied to the commercial driver license (CDL) for the trucking industry. Nevertheless, this is an uphill battle to convince CDL administrators to integrate modern technology into the CDL program instead of using the traditional daily business of manual testing. This is because the cost of trucking industry live operations is still relatively affordable; individuals and companies are reluctant to adopt the use of the modeling and simulation driving or testing system. Fortunately, cost is not the only variable to consider for the training and testing administrators and their management. There is a need to expand the use of technology to support live operations. The safety of the student, trainer, and tester should be taken into account. The availability of training or testing scenarios is also an influencing factor. Ultimately, the most important factor is driving safety on the American road. The relationship of accidents with driver license fraud has led the Federal Department of Transportation to want to reduce fraud in third-party Commercial Driver License (CDL) administration. Although it is not a perfect solution that can fix all, the utilization of simulation technologies for driving assessment could be a solution to help reduce fraud if it is applied correctly. The Department of Transportation (DOT) authorized the statesÃ‚Â' independent authority to administrate the local CDL including the use of the Third-Party Tester (TPT). As a result, some criminal activities prompted the Federal investigation to recommend changes and to fund the states to take action to stay in compliance with the Federal regulation. This is the opportunity for the state CDL administrator to explore the use of M&S to support its mission. Recall, those arguments for the use of the M&S is the thought of safety in saving lives, economic incentive in reducing the operational cost, and reducing the carbon footprint via using simulation. This makes simulation a viable resource. This paper will report the research study of using the computer based testing modeling and simulation tools to replace or augment the current state examiner as means of assessing the CDL TPT proficiency in basic backing skills. This pilot study of this system has several aspects to address. The scenarios must be relevant to test the knowledge of the TPT by using closely comparable scenarios to the current manual testing method. The scenario-based simulation should incorporate randomness to provide a greater sense of reality. In addition, the reconfigurable built-in random behavior scenarios provide the administrator greater control of behaviors and allow the administrator to be able to select among the random scenarios. Finally, the paper will present the data sampling from relevant participants of the CDL TPT and methodology applied. The analysis of data presents in this research study will be valuable for the State and Federal CDL administrator to consider the pros and cons of applying or adding a computer based simulation to their current testing methodology.
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Date Issued: 2010
Identifier: CFE0003222, ucf:48577
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003222

Title: RELIABILITY STUDY OF INGAP/GAAS HETEROJUNCTION BIPOLAR TRANSISTOR MMIC TECHNOLOGY BY CHARACTERIZATION, MODELING AND SIMULATION.
Creator: LIU, XIANG, Liou, Juin J., University of Central Florida
Abstract / Description: Recent years have shown real advances of microwave monolithic integrated circuits (MMICs) for millimeter-wave frequency systems, such as wireless communication, advanced imaging, remote sensing and automotive radar systems, as MMICs can provide the size, weight and performance required for these systems. Traditionally, GaAs pseudomorphic high electron mobility transistor (pHEMT) or InP based MMIC technology has dominated in millimeter-wave frequency applications because of their high fT and...
Show moreRecent years have shown real advances of microwave monolithic integrated circuits (MMICs) for millimeter-wave frequency systems, such as wireless communication, advanced imaging, remote sensing and automotive radar systems, as MMICs can provide the size, weight and performance required for these systems. Traditionally, GaAs pseudomorphic high electron mobility transistor (pHEMT) or InP based MMIC technology has dominated in millimeter-wave frequency applications because of their high fT and fmax as well as their superior noise performance. But these technologies are very expensive. Thus, for low cost and high performance applications, InGaP/GaAs heterojunction bipolar transistors (HBTs) are quickly becoming the preferred technology to be used due to their inherently excellent characteristics. These features, together with the need for only one power supply to bias the device, make InGaP/GaAs HBTs very attractive for the design of high performance fully integrated MMICs. With the smaller dimensions for improving speed and functionality of InGaP/GaAs HBTs, which dissipate large amount of power and result in heat flux accumulated in the device junction, technology reliability issues are the first concern for the commercialization. As the thermally triggered instabilities often seen in InGaP/GaAs HBTs, a carefully derived technique to define the stress conditions of accelerated life test has been employed in our study to acquire post-stress device characteristics for the projection of long-term device performance degradation pattern. To identify the possible origins of the post-stress device behaviors observed experimentally, a two dimensional (2-D) TCAD numerical device simulation has been carried out. Using this approach, it is suggested that the acceptor-type trapping states located in the emitter bulk are responsible for the commonly seen post-stress base current instability over the moderate base-emitter voltage region. HBT-based MMIC performance is very sensitive to the variation of core device characteristics and the reliability issues put the limit on its radio frequency (RF) behaviors. While many researchers have reported the observed stress-induced degradations of GaAs HBT characteristics, there has been little published data on the full understanding of stress impact on the GaAs HBT-based MMICs. If care is not taken to understand this issue, stress-induced degradation paths can lead to built-in circuit failure during regular operations. However, detection of this failure may be difficult due to the circuit complexity and lead to erroneous data or output conditions. Thus, a practical and analytical methodology has been developed to predict the stress impacts on HBT-based MMICs. It provides a quick way and guidance for the RF design engineer to evaluate the circuit performance with reliability considerations. Using the present existing EDA tools (Cadance SpectreRF and Agilent ADS) with the extracted pre- and post-stress transistor models, the electrothermal stress effects on InGaP/GaAs HBT-based RF building blocks including power amplifier (PA), low-noise amplifier (LNA) and oscillator have been systematically evaluated. This provides a potential way for the RF/microwave industry to save tens of millions of dollars annually in testing costs. The world now stands at the threshold of the age of advanced GaAs HBT MMIC technology and researchers have been exploring here for years. The reliability of GaAs HBT technology is no longer the post-design evaluation, but the pre-design consideration. The successful and fruitful results of this dissertation provide methods and guidance for the RF designers to achieve more reliable RF circuits with advanced GaAs HBT technology in the future.
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Date Issued: 2011
Identifier: CFE0003904, ucf:48744
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003904

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VISSIM (7)	+ -
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