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(1 - 16 of 16)
- Title
- The Effects of Tactile Displays on the Perception of Target Distance.
- Creator
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White, Timothy, Hancock, Peter, Mouloua, Mustapha, Szalma, James, Rupert, Angus, University of Central Florida
- Abstract / Description
-
Because vital information can be missed by Soldiers in combat environments that tax the eyes and the ears, it is imperative that alternative techniques be investigated to determine their potential in relaying this information in an effective way. This research investigated the use of a tactile display for providing distance and azimuth information about enemy targets. In a series of three experiments, participants were asked to engage enemy targets while utilizing cues that provided location...
Show moreBecause vital information can be missed by Soldiers in combat environments that tax the eyes and the ears, it is imperative that alternative techniques be investigated to determine their potential in relaying this information in an effective way. This research investigated the use of a tactile display for providing distance and azimuth information about enemy targets. In a series of three experiments, participants were asked to engage enemy targets while utilizing cues that provided location information. In Experiment 1, two tactile cueing techniques (i.e., varying intensity and varying pulse rate) and three auditory cueing techniques (i.e., non-spatial speech, varying frequency of 3-D tones, and varying pulse rate of 3-D tones) were used to provide distance and azimuth information about enemy targets. Findings indicated that more participants preferred the tactile pulse cue and the non-spatial speech cue. There were no significant differences in performance among the tactile and the auditory cues, respectively. However, both the tactile cue types resulted in better performance and lower mental workload than the three auditory cue types. In Experiment 2, performance was investigated among the preferred tactile pulse cue and the non-spatial speech cue as well as a tactile direction only cue (i.e., no distance information), a visual cue, and a no cueing control. Findings indicated that both the tactile cue types resulted in better performance and lower mental workload than the other cue conditions. Experiment 3, was a multimodal investigation in which performance was investigated among combinations of the non-spatial speech, visual, and tactile pulse cues employed in Experiment 2. Findings indicated that cue combinations that included the tactile pulse cue resulted in better performance and lower mental workload than the cue combination without the tactile pulse cue. Overall, the findings support the notion of employing tactile displays as a communication means to provide azimuth and distance information to Soldiers about enemy targets, either as a unimodal cue or in concert with other cue types.
Show less - Date Issued
- 2016
- Identifier
- CFE0006418, ucf:51450
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006418
- Title
- ENHANCING SITUATIONAL AWARENESS THROUGH HAPTICS INTERACTION IN VIRTUAL ENVIRONMENT TRAINING SYSTMES.
- Creator
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Hale, Kelly, Stanney, Kay, University of Central Florida
- Abstract / Description
-
Virtual environment (VE) technology offers a viable training option for developing knowledge, skills and attitudes (KSA) within domains that have limited live training opportunities due to personnel safety and cost (e.g., live fire exercises). However, to ensure these VE training systems provide effective training and transfer, designers of such systems must ensure that training goals and objectives are clearly defined and VEs are designed to support development of KSAs required. Perhaps the...
Show moreVirtual environment (VE) technology offers a viable training option for developing knowledge, skills and attitudes (KSA) within domains that have limited live training opportunities due to personnel safety and cost (e.g., live fire exercises). However, to ensure these VE training systems provide effective training and transfer, designers of such systems must ensure that training goals and objectives are clearly defined and VEs are designed to support development of KSAs required. Perhaps the greatest benefit of VE training is its ability to provide a multimodal training experience, where trainees can see, hear and feel their surrounding environment, thus engaging them in training scenarios to further their expertise. This work focused on enhancing situation awareness (SA) within a training VE through appropriate use of multimodal cues. The Multimodal Optimization of Situation Awareness (MOSA) model was developed to identify theoretical benefits of various environmental and individual multimodal cues on SA components. Specific focus was on benefits associated with adding cues that activated the haptic system (i.e., kinesthetic/cutaneous sensory systems) or vestibular system in a VE. An empirical study was completed to evaluate the effectiveness of adding two independent spatialized tactile cues to a Military Operations on Urbanized Terrain (MOUT) VE training system, and how head tracking (i.e., addition of rotational vestibular cues) impacted spatial awareness and performance when tactile cues were added during training. Results showed tactile cues enhanced spatial awareness and performance during both repeated training and within a transfer environment, yet there were costs associated with including two cues together during training, as each cue focused attention on a different aspect of the global task. In addition, the results suggest that spatial awareness benefits from a single point indicator (i.e., spatialized tactile cues) may be impacted by interaction mode, as performance benefits were seen when tactile cues were paired with head tracking. Future research should further examine theoretical benefits outlined in the MOSA model, and further validate that benefits can be realized through appropriate activation of multimodal cues for targeted training objectives during training, near transfer and far transfer (i.e., real world performance).
Show less - Date Issued
- 2006
- Identifier
- CFE0001414, ucf:47034
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001414
- Title
- TACTILE WORKING MEMORY AND MULTIMODAL LOADING.
- Creator
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Terrence, Peter, Gilson, Richard, University of Central Florida
- Abstract / Description
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This work explored the role of spatial grouping, set size, and stimulus probe modality using a recall task for visual, auditory, and tactile information. The effects of different working memory (WM) loading task modalities were also examined. The Gestalt spatial organizing principle of grouping showed improvements in response times for visual and tactile stimulus probes with large set sizes and apparently allowed participants to effectively chunk the information. This research suggests that...
Show moreThis work explored the role of spatial grouping, set size, and stimulus probe modality using a recall task for visual, auditory, and tactile information. The effects of different working memory (WM) loading task modalities were also examined. The Gestalt spatial organizing principle of grouping showed improvements in response times for visual and tactile stimulus probes with large set sizes and apparently allowed participants to effectively chunk the information. This research suggests that tactile information may use spatial characteristics typically associated with visual information, as well as sequential characteristics normally associated with verbal information. Based on these results, a reformulation of WM is warranted to remove the constraints of the input modality on processing types. The input modalities appear to access both a spatial sketchpad and a temporally-based sequence loop. Implications for multisensory research and display design are discussed.
Show less - Date Issued
- 2008
- Identifier
- CFE0002084, ucf:47564
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002084
- Title
- A COMPARISON OF ATTENTIONAL RESERVE CAPACITY ACROSS THREE SENSORY MODALITIES.
- Creator
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Brill, John, Gilson, Richard, University of Central Florida
- Abstract / Description
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There are two theoretical approaches to the nature of attentional resources. One proposes a single, flexible pool of cognitive resources; the other poses there are multiple resources. This study was designed to systematically examine whether there is evidence for multiple resource theory using a counting task consisting of visual, auditory, and tactile signals using two experiments. The goal of the first experiment was the validation of a multi-modal secondary loading task. Thirty-two...
Show moreThere are two theoretical approaches to the nature of attentional resources. One proposes a single, flexible pool of cognitive resources; the other poses there are multiple resources. This study was designed to systematically examine whether there is evidence for multiple resource theory using a counting task consisting of visual, auditory, and tactile signals using two experiments. The goal of the first experiment was the validation of a multi-modal secondary loading task. Thirty-two participants performed nine variations of a multi-modal counting task incorporating three modalities and three demand levels. Performance and subjective ratings of workload were measured for each of the nine conditions of the within-subjects design. Significant differences were found on the basis of task demand level, irrespective of modality. Moreover, the perceived workload associated with the tasks differed by task demand level and not by modality. These results suggest the counting task is a valid means of imposing task demands across multiple modalities. The second experiment used the same counting task as a secondary load to a primary visual monitoring task, the system monitoring component of the Multi-Attribute Task Battery (MATB). The experimental conditions consisted of performing the system monitoring task alone as a reference and performing system monitoring combined with visual, auditory, or tactile counting. Thirty-one participants were exposed to all four experimental conditions in a within-subjects design. Performance on the primary and secondary tasks was measured, and subjective workload was assessed for each condition. Participants were instructed to maintain performance on the primary task, irrespective of condition, which they did so effectively. Secondary task performance for the visual-auditory and visual-tactile conditions was significantly better than for the visual-visual dual task condition. Subjective workload ratings were also consistent with the performance measures. These results clearly indicate that there is less interference for cross-modal tasks than for intramodal tasks. These results add evidence to multiple resource theory. Finally, these results have practical implications that include human performance assessment for display and alarm development, assessment of attentional reserve capacity for adaptive automation systems, and training.
Show less - Date Issued
- 2007
- Identifier
- CFE0001660, ucf:47234
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001660
- Title
- Investigation of Tactile Displays for Robot to Human Communication.
- Creator
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Barber, Daniel, Reinerman, Lauren, Jentsch, Florian, Lackey, Stephanie, Leonessa, Alexander, University of Central Florida
- Abstract / Description
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Improvements in autonomous systems technology and a growing demand within military operations are spurring a revolution in Human-Robot Interaction (HRI). These mixed-initiative human-robot teams are enabled by Multi-Modal Communication (MMC), which supports redundancy and levels of communication that are more robust than single mode interaction. (Bischoff (&) Graefe, 2002; Partan (&) Marler, 1999). Tactile communication via vibrotactile displays is an emerging technology, potentially...
Show moreImprovements in autonomous systems technology and a growing demand within military operations are spurring a revolution in Human-Robot Interaction (HRI). These mixed-initiative human-robot teams are enabled by Multi-Modal Communication (MMC), which supports redundancy and levels of communication that are more robust than single mode interaction. (Bischoff (&) Graefe, 2002; Partan (&) Marler, 1999). Tactile communication via vibrotactile displays is an emerging technology, potentially beneficial to advancing HRI. Incorporation of tactile displays within MMC requires developing messages equivalent in communication power to speech and visual signals used in the military. Toward that end, two experiments were performed to investigate the feasibility of a tactile language using a lexicon of standardized tactons (tactile icons) within a sentence structure for communication of messages for robot to human communication. Experiment one evaluated tactons from the literature with standardized parameters grouped into categories (directional, dynamic, and static) based on the nature and meaning of the patterns to inform design of a tactile syntax. Findings of this experiment revealed directional tactons showed better performance than non-directional tactons, therefore syntax for experiment two composed of a non-directional and a directional tacton was more likely to show performance better than chance. Experiment two tested the syntax structure of equally performing tactons identified from experiment one, revealing participants' ability to interpret tactile sentences better than chance with or without the presence of an independent work imperative task. This finding advanced the state of the art in tactile displays from one to two word phrases facilitating inclusion of the tactile modality within MMC for HRI.
Show less - Date Issued
- 2012
- Identifier
- CFE0004778, ucf:49800
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004778
- Title
- The Bridging Technique: Crossing Over the Modality Shifting Effect.
- Creator
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Alicia, Thomas, Mouloua, Mustapha, Hancock, Peter, Szalma, James, Pharmer, James, University of Central Florida
- Abstract / Description
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Operator responsiveness to critical alarm/alert display systems must rely on faster and safer behavioral responses in order to ensure mission success in complex environments such as the operator station of an Unmanned Aerial System (UAS). An important design consideration for effective UAS interfaces is how to map these critical alarm/alert display systems to an appropriate sensory modality (e.g., visual or auditory) (Sarter, 2006). For example, if an alarm is presented during a mission in a...
Show moreOperator responsiveness to critical alarm/alert display systems must rely on faster and safer behavioral responses in order to ensure mission success in complex environments such as the operator station of an Unmanned Aerial System (UAS). An important design consideration for effective UAS interfaces is how to map these critical alarm/alert display systems to an appropriate sensory modality (e.g., visual or auditory) (Sarter, 2006). For example, if an alarm is presented during a mission in a modality already highly taxed or overloaded, this can result in increased response time (RT), thereby decreasing operator performance (Wickens, 1976). To overcome this problem, system designers may allow the switching of the alarm display from a highly-taxed to a less-taxed modality (Stanney et al., 2004). However, this modality switch may produce a deleterious effect known as the Modality Shifting Effect (MSE) that erodes the expected performance gain (Spence (&) Driver, 1997). The goal of this research was to empirically examine a technique called bridging which allows the transitioning of a cautionary alarm display from one modality to another while simultaneously counteracting the Modality Shifting Effect.Sixty-four participants were required to complete either a challenging visual or auditory task using a computer-based UAS simulation environment while responding to both visual and auditory alarms. An approach was selected which utilized two 1 (task modality) x 2 (switching technique) ANCOVAs and one 2 (modality) x 2 (technique) ANCOVA, using baseline auditory and visual RT as covariates, to examine differences in alarm response times when the alert modality was changed abruptly or with the bridging technique from a highly loaded sensory channel to an underloaded sensory channel. It was hypothesized that the bridging technique condition would show faster response times for a new unexpected modality versus the abrupt switching condition. The results indicated only a marginal decrease in response times for the auditory alerts and a larger yet not statistically significant effect for the visual alerts; results were also not statistically significant for the analysis collapsed across modality. Findings suggest that there may be some benefit of the bridging technique on performance of alarm responsiveness, but further research is still needed before suggesting generalizable design guidelines for switching modalities which can apply in a variety of complex human-machine systems.
Show less - Date Issued
- 2015
- Identifier
- CFE0005568, ucf:50283
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005568
- Title
- The Normalization Process of Multimodal Composition: "Unseeing" People of Color in Multimodal Composition Scholarship.
- Creator
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Davis, Yumani, Rios, Gabriela, Roozen, Kevin, Pigg, Stacey, University of Central Florida
- Abstract / Description
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This study attempts to identify normalization cues within multimodal scholarship to highlight moments of (")un-seeing(") multimodal composing practices and theoretical contributions from non-Western traditions. Advocates of this approach to teaching composition understand it as an effective way for incorporating other voices into the curricular structures of composition courses. However, the instructional resources do not include or cite research that does not lend itself easily to dominant...
Show moreThis study attempts to identify normalization cues within multimodal scholarship to highlight moments of (")un-seeing(") multimodal composing practices and theoretical contributions from non-Western traditions. Advocates of this approach to teaching composition understand it as an effective way for incorporating other voices into the curricular structures of composition courses. However, the instructional resources do not include or cite research that does not lend itself easily to dominant views of composing within academia. I assert that academia must go further with how value is assessed. There is research that acknowledges the multiliteracies practices found within subcultures of America, and plenty of work that deems the communicative practices observed in these subcultural communities as valuable. However, it is more than just including and citing scholarship from and about people of color's compositional practices, academia must also employ these ways of knowing and being to fully empower students and utilize the knowledge that the students bring with them to the FYC classroom. The dominant assignment genre in academia is the academic essay. Other dominant methods of communication and transferring scholarship are the journal article, annotated bibliography, proposal, and personal essay. Not to mention the many scholars who have critiqued academia for privileging print literacies, which although may be multimodal, promotes a multimodality of one culture and ideological standpoint. Although the seminal texts from the study offer exceptional multimodal composition research and classroom resources, if we can agree that (")the mission of education is to ensure that all students benefit from learning in ways that allow them to participate fully in public, community, and economic life(") and that literacy pedagogy, essentially what the FYC course offers, (")is expected to play a particularly important role in fulfilling this mission,(") then failing to see the value and utilize the scholarship from and about people of color ensures those that are marginalized continue to be (")un-seen(") and students remain unprepared for the tasks of composing and communicating outside of school (New London Group 60).
Show less - Date Issued
- 2015
- Identifier
- CFE0005779, ucf:50071
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005779
- Title
- OPTIMIZING THE DESIGN OF MULTIMODAL USER INTERFACES.
- Creator
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Reeves, Leah, Stanney, Kay, University of Central Florida
- Abstract / Description
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Due to a current lack of principle-driven multimodal user interface design guidelines, designers may encounter difficulties when choosing the most appropriate display modality for given users or specific tasks (e.g., verbal versus spatial tasks). The development of multimodal display guidelines from both a user and task domain perspective is thus critical to the achievement of successful human-system interaction. Specifically, there is a need to determine how to design task information...
Show moreDue to a current lack of principle-driven multimodal user interface design guidelines, designers may encounter difficulties when choosing the most appropriate display modality for given users or specific tasks (e.g., verbal versus spatial tasks). The development of multimodal display guidelines from both a user and task domain perspective is thus critical to the achievement of successful human-system interaction. Specifically, there is a need to determine how to design task information presentation (e.g., via which modalities) to capitalize on an individual operator's information processing capabilities and the inherent efficiencies associated with redundant sensory information, thereby alleviating information overload. The present effort addresses this issue by proposing a theoretical framework (Architecture for Multi-Modal Optimization, AMMO) from which multimodal display design guidelines and adaptive automation strategies may be derived. The foundation of the proposed framework is based on extending, at a functional working memory (WM) level, existing information processing theories and models with the latest findings in cognitive psychology, neuroscience, and other allied sciences. The utility of AMMO lies in its ability to provide designers with strategies for directing system design, as well as dynamic adaptation strategies (i.e., multimodal mitigation strategies) in support of real-time operations. In an effort to validate specific components of AMMO, a subset of AMMO-derived multimodal design guidelines was evaluated with a simulated weapons control system multitasking environment. The results of this study demonstrated significant performance improvements in user response time and accuracy when multimodal display cues were used (i.e., auditory and tactile, individually and in combination) to augment the visual display of information, thereby distributing human information processing resources across multiple sensory and WM resources. These results provide initial empirical support for validation of the overall AMMO model and a sub-set of the principle-driven multimodal design guidelines derived from it. The empirically-validated multimodal design guidelines may be applicable to a wide range of information-intensive computer-based multitasking environments.
Show less - Date Issued
- 2007
- Identifier
- CFE0001636, ucf:47237
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001636
- Title
- Mediated Physicality: Inducing Illusory Physicality of Virtual Humans via Their Interactions with Physical Objects.
- Creator
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Lee, Myungho, Welch, Gregory, Wisniewski, Pamela, Hughes, Charles, Bruder, Gerd, Wiegand, Rudolf, University of Central Florida
- Abstract / Description
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The term virtual human (VH) generally refers to a human-like entity comprised of computer graphics and/or physical body. In the associated research literature, a VH can be further classified as an avatar(-)a human-controlled VH, or an agent(-)a computer-controlled VH. Because of the resemblance with humans, people naturally distinguish them from non-human objects, and often treat them in ways similar to real humans. Sometimes people develop a sense of co-presence or social presence with the...
Show moreThe term virtual human (VH) generally refers to a human-like entity comprised of computer graphics and/or physical body. In the associated research literature, a VH can be further classified as an avatar(-)a human-controlled VH, or an agent(-)a computer-controlled VH. Because of the resemblance with humans, people naturally distinguish them from non-human objects, and often treat them in ways similar to real humans. Sometimes people develop a sense of co-presence or social presence with the VH(-)a phenomenon that is often exploited for training simulations where the VH assumes the role of a human. Prior research associated with VHs has primarily focused on the realism of various visual traits, e.g., appearance, shape, and gestures. However, our sense of the presence of other humans is also affected by other physical sensations conveyed through nearby space or physical objects. For example, we humans can perceive the presence of other individuals via the sound or tactile sensation of approaching footsteps, or by the presence of complementary or opposing forces when carrying a physical box with another person. In my research, I exploit the fact that these sensations, when correlated with events in the shared space, affect one's feeling of social/co-presence with another person. In this dissertation, I introduce novel methods for utilizing direct and indirect physical-virtual interactions with VHs to increase the sense of social/co-presence with the VHs(-)an approach I refer to as mediated physicality. I present results from controlled user studies, in various virtual environment settings, that support the idea that mediated physicality can increase a user's sense of social/co-presence with the VH, and/or induced realistic social behavior. I discuss relationships to prior research, possible explanations for my findings, and areas for future research.
Show less - Date Issued
- 2019
- Identifier
- CFE0007485, ucf:52687
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007485
- Title
- Nonlinear Dynamics in Multimode Optical Fibers.
- Creator
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Eftekhar, Mohammad Amin, Christodoulides, Demetrios, Amezcua Correa, Rodrigo, Li, Guifang, Kaup, David, University of Central Florida
- Abstract / Description
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Multimode optical fibers have recently reemerged as a viable platform for addressing a number of long-standing issues associated with information bandwidth requirements and power-handling capabilities. The complex nature of heavily multimoded systems can be effectively exploited to observe altogether novel physical effects arising from spatiotemporal and intermodal linear and nonlinear processes. Here, we have studied nonlinear dynamics in multimode optical fibers (MMFs) in both the normal...
Show moreMultimode optical fibers have recently reemerged as a viable platform for addressing a number of long-standing issues associated with information bandwidth requirements and power-handling capabilities. The complex nature of heavily multimoded systems can be effectively exploited to observe altogether novel physical effects arising from spatiotemporal and intermodal linear and nonlinear processes. Here, we have studied nonlinear dynamics in multimode optical fibers (MMFs) in both the normal and anomalous dispersion regimes. In the anomalous dispersion regime, the nonlinearity leads to a formation of spatiotemporal 3-D solitons. Unlike in single-mode fibers, these solitons are not unique and their properties can be modified through the additional degrees of freedom offered by these multimoded settings. In addition, soliton related processes such as soliton fission and dispersive wave generation will be also drastically altered in such multimode systems. Our theoretical work unravels some of the complexities of the underlying dynamics and helps us better understand these effects. The nonlinear dynamics in such multimode systems can be accelerated through a judicious fiber design. A cancelation of Raman self-frequency shifts and Blue-shifting multimode solitons were observed in such settings as a result of an acceleration of intermodal oscillations. Spatiotemporal instabilities in parabolic-index multimode fibers will also be discussed. In the normal dispersion regime, this effect can be exploited to generate an ultrabroad and uniform supercontinuum that extends more than 2.5 octaves. To do so, the unstable spectral regions are pushed away from the pump, thus sweeping the entire spectrum. Multimode parabolic pulses were also predicted and observed in passive normally dispersive tapered MMFs. These setting can obviate the harsh bandwidth limitation present in single-mode system imposed by gain medium and be effectively used for realizing high power multimode fiber lasers. Finally, an instant and efficient second-harmonic generation was observed in the multimode optical fibers. Through a modification of initial conditions, the efficiency of this process could be enhanced to a record high of %6.5.
Show less - Date Issued
- 2018
- Identifier
- CFE0007399, ucf:52063
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007399
- Title
- ELECTRO-OPTICAL AND ALL-OPTICAL SWITCHING IN MULTIMODE INTERFERENCE WAVEGUIDES INCORPORATING SEMICONDUCTOR NANOSTRUCTURES.
- Creator
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Bickel, Nathan, LiKamWa, Patrick, University of Central Florida
- Abstract / Description
-
The application of epitaxially grown, III-V semiconductor-based nanostructures to the development of electro-optical and all-optical switches is investigated through the fabrication and testing of integrated photonic devices designed using multimode interference (MMI) waveguides. The properties and limitations of the materials are explored with respect to the operation of those devices through electrical carrier injection and optical pumping. MMI waveguide geometry was employed as it offered...
Show moreThe application of epitaxially grown, III-V semiconductor-based nanostructures to the development of electro-optical and all-optical switches is investigated through the fabrication and testing of integrated photonic devices designed using multimode interference (MMI) waveguides. The properties and limitations of the materials are explored with respect to the operation of those devices through electrical carrier injection and optical pumping. MMI waveguide geometry was employed as it offered advantages such as a very compact device footprint, low polarization sensitivity, large bandwidth and relaxed fabrication tolerances when compared with conventional single-mode waveguide formats. The first portion of this dissertation focuses on the characterization of the materials and material processing techniques for the monolithic integration of In0.15Ga0.85As/GaAs self-assembled quantum dots (SAQD) and InGaAsP/InGaAsP multiple quantum wells (MQW). Supplemental methods for post-growth bandgap tuning and waveguide formation were developed, including a plasma treatment process which is demonstrated to reliably inhibit thermally induced interdiffusion of Ga and In atoms in In0.15Ga0.85As/GaAs quantum dots. The process is comparable to the existing approach of capping the SAQD wafer with TiO2, while being simpler to implement along-side companion techniques such as impurity free vacancy disordering. Study of plasma-surface interactions in both wafer structures suggests that the effect may be dependent on the composition of the contact layer. The second portion of this work deals with the design, fabrication, and the testing of MMI switches which are used to investigate the limits of electrical current control when employing SAQD as the active core material. A variable power splitter based on a 3-dB MMI coupler is used to analyze the effects of sub-microsecond electrical current pulses in relation to carrier and thermal nonlinearities. Electrical current controlled switching of the variable power splitter and a tunable 2 x 2 MMI coupler is also demonstrated. The third part of this dissertation explores the response of In0.15Ga0.85As/GaAs SAQD waveguide structures to photogenerated carriers. Also presented is a simple, but effective, design modification to the 2 x 2 MMI cross-coupler switch that allows control over the carrier distribution within the MMI waveguide. This technique is combined with selective-area bandgap tuning to demonstrate a compact, working, all-optical MMI based switch.
Show less - Date Issued
- 2010
- Identifier
- CFE0003220, ucf:48568
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003220
- Title
- INTEGRATED INP PHOTONIC SWITCHES.
- Creator
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May-Arrioja, Daniel, LiKamWa, Patrick, University of Central Florida
- Abstract / Description
-
Photonic switches are becoming key components in advanced optical networks because of the large variety of applications that they can perform. One of the key advantages of photonic switches is that they redirect or convert light without having to make any optical to electronic conversions and vice versa, thus allowing networking functions to be lowered into the optical layer. InP-based switches are particularly attractive because of their small size, low electrical power consumption, and...
Show morePhotonic switches are becoming key components in advanced optical networks because of the large variety of applications that they can perform. One of the key advantages of photonic switches is that they redirect or convert light without having to make any optical to electronic conversions and vice versa, thus allowing networking functions to be lowered into the optical layer. InP-based switches are particularly attractive because of their small size, low electrical power consumption, and compatibility with integration of laser sources, photo-detectors, and electronic components. In this dissertation the development of integrated InP photonic switches using an area-selective zinc diffusion process has been investigated. The zinc diffusion process is implemented using a semi-sealed open-tube diffusion technique. The process has proven to be highly controllable and reproducible by carefully monitoring of the diffusion parameters. Using this technique, isolated p-n junctions exhibiting good I-V characteristics and breakdown voltages greater than 10 V can be selectively defined across a semiconductor wafer. A series of Mach-Zehnder interferometric (MZI) switches/modulators have been designed and fabricated. Monolithic integration of 1x2 and 2x2 MZI switches has been demonstrated. The diffusion process circumvents the need for isolation trenches, and hence optical losses can be significantly reduced. An efficient optical beam steering device based on InGaAsP multiple quantum wells is also demonstrated. The degree of lateral current spreading is easily regulated by controlling the zinc depth, allowing optimization of the injected currents. Beam steering over a 21 microns lateral distance with electrical current values as low as 12.5 mA are demonstrated. Using this principle, a reconfigurable 1x3 switch has been implemented with crosstalk levels better than -17 dB over a 50 nm wavelength range. At these low electrical current levels, uncooled and d.c. bias operation is made feasible. The use of multimode interference (MMI) structures as active devices have also been investigated. These devices operate by selective refractive index perturbation on very specific areas within the MMI structure, and this is again realized using zinc diffusion. Several variants such as a compact MMI modulator that is as short as 350 µm, a robust 2x2 photonic switch and a tunable MMI coupler have been demonstrated.
Show less - Date Issued
- 2006
- Identifier
- CFE0001368, ucf:47007
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001368
- Title
- MULTI-MODAL READING FOR LOW LEVEL READERS.
- Creator
-
O'Neal, Jamie, Dombrowski, Paul, University of Central Florida
- Abstract / Description
-
The value of this research hinges on the idea that exchanging illustrations for descriptive text can provide appropriate schemas for students with reading difficulties and thereby improve their comprehension and vocabulary acquisition. The research in this dissertation is based on theories and earlier research in the fields of psychology, education, reading, and narratology. A review of these fields offers a variety of perspectives on the processes involved in reading and comprehension. These...
Show moreThe value of this research hinges on the idea that exchanging illustrations for descriptive text can provide appropriate schemas for students with reading difficulties and thereby improve their comprehension and vocabulary acquisition. The research in this dissertation is based on theories and earlier research in the fields of psychology, education, reading, and narratology. A review of these fields offers a variety of perspectives on the processes involved in reading and comprehension. These processes range from the physical systems involved in reading (e.g., early childhood development, eye movement) to the psychological systems, which include cognitive load theory as well as image and text processing models. This study compares two reading methods by analyzing studentsÂÂ' vocabulary and comprehension gains. Both groups read the same text and completed the same pre- and post-tests. The control group read the text from the book which was text only. The experimental group read from a modified text on the computer screen. The text was modified by replacing some sentences with images designed to transmit the same information (e.g., descriptions of the setting, vocabulary items) in a graphic format. The images were in-line with the text, and designed to be read as part of the story, not as additional illustrations. Final analysis shows that the experimental format performed as well as the control format for most students. However, students who have learning disabilities, particularly language learners who have learning disabilities, did not make gains in the text only control format. These same students did show statistically significant gains with the experimental format, particularly the section of reading where the vocabulary words were explicitly presented in the images. Disparate, non-homogenous groupings of students reflect the actual teaching and learning circumstances in the school, as required by the school system. This situation thus represents the actual status quo situation faced by teachers in our school. We leave it to future researchers to work with more homogenous groups of students in order to attain clearer, stronger and more plaintively useful results.
Show less - Date Issued
- 2010
- Identifier
- CFE0003306, ucf:48486
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003306
- Title
- VISUAL AND VERBAL RHETORIC IN HOWARD CHANDLER CHRISTY'S WAR-RELATED POSTERS OF WOMEN DURING THE WORLD WAR I ERA: A FEMINIST PERSPECTIVE.
- Creator
-
Gomrad, Mary Ellen, Kitalong, Karla, University of Central Florida
- Abstract / Description
-
This thesis explores the development of a series of posters created by Howard Chandler Christy during the World War I era. During this time, Christy was a Department of Pictorial Publicity (DPP) committee artist commissioned by the committee chair, Charles Dana Gibson. The DPP was part of the Committee on Public Information (CPI) developed by the Woodrow Wilson administration to generate the propaganda necessary to gain the support of the American people to enter World War I. The CPI was...
Show moreThis thesis explores the development of a series of posters created by Howard Chandler Christy during the World War I era. During this time, Christy was a Department of Pictorial Publicity (DPP) committee artist commissioned by the committee chair, Charles Dana Gibson. The DPP was part of the Committee on Public Information (CPI) developed by the Woodrow Wilson administration to generate the propaganda necessary to gain the support of the American people to enter World War I. The CPI was headed up by George Creel, a journalist and politician, who used advertising techniques to create the first full-scale propaganda effort in United States history. American poster images of women during World War I represent an era when propaganda posters came of age. These iconographic interpretations depicted in political propaganda helped shape the history of the twentieth century. While exploring these portrayals of women, the observer looks through a historical lens to contemplate the role of propaganda in the American war effort, while considering the disparity between images of women and the reality of their experiences in the patriarchal society in which they lived. Howard Chandler Christy's war-related posters represented the gendered rhetoric of a social order that functioned under the well-established assumption that men and women both had their place in society based on gender-specific stereotypic characteristics. Women were central to propaganda posters from this era; their images were widely used in posters encouraging Americans to support the war effort. With few exceptions, these representations perpetuated traditional concepts of appropriate gender roles. Posters often used women as icons characterizing the nation in time of war. For example, a beautiful woman, with a backdrop of the United States flag or sometimes even dressed in Old Glory, suggested why the nation was fighting. Some posters explicitly used beautiful women to signify that America's honor was at stake and we needed fighting men to protect it. The poster art form spread rapidly during the early twentieth century, putting a woman in her place rather than challenging the historical circumstances that created the complex, problematic issues related to the visual representation. Reading these posters as cultural texts, it is apparent that women's images are central to gaining an understanding of the social norms and cultural expectations.
Show less - Date Issued
- 2007
- Identifier
- CFE0001807, ucf:52848
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001807
- Title
- Improving fairness, throughput and blocking performance for long haul and short reach optical networks.
- Creator
-
Tariq, Sana, Bassiouni, Mostafa, Zou, Changchun, Turgut, Damla, Li, Guifang, University of Central Florida
- Abstract / Description
-
Innovations in optical communication are expected to transform the landscape of global communications, internet and datacenter networks. This dissertation investigates several important issues in optical communication such as fairness, throughput, blocking probability and differentiated quality of service (QoS). Novel algorithms and new approaches have been presented to improve the performance of optical circuit switching (OCS) and optical burst switching (OBS) for long haul, and datacenter...
Show moreInnovations in optical communication are expected to transform the landscape of global communications, internet and datacenter networks. This dissertation investigates several important issues in optical communication such as fairness, throughput, blocking probability and differentiated quality of service (QoS). Novel algorithms and new approaches have been presented to improve the performance of optical circuit switching (OCS) and optical burst switching (OBS) for long haul, and datacenter networks. Extensive simulations tests have been conducted to evaluate the effectiveness of the proposed algorithms. These simulation tests were performed over a number of network topologies such as ring, mesh and U.S. Long-Haul, some high processing computing (HPC) topologies such as 2D and 6D mesh torus topologies and modern datacenter topologies such as FatTree and BCube.Two new schemes are proposed for long haul networks to improve throughput and hop count fairness in OBS networks. The idea is motivated by the observation that providing a slightly more priority to longer bursts over short bursts can significantly improve the throughput of the OBS networks without adversely affecting hop-count fairness. The results of extensive performance tests have shown that proposed schemes improve the throughput of optical OBS networks and enhance the hop-count fairness. Another contribution of this dissertation is the research work on developing routing and wavelength assignment schemes in multimode fiber networks. Two additional schemes for long haul networks are presented and evaluated over multimode fiber networks. First for alleviating the fairness problem in OBS networks using wavelength-division multiplexing as well as mode-division multiplexing while the second scheme for achieving higher throughput without sacrificing hop count fairness.We have also shown the significant benefits of using both mode division multiplexing and wavelength division multiplexing in real-life short-distance optical networks such as the optical circuit switching networks used in the hybrid electronic-optical switching architectures for datacenters. We evaluated four mode and wavelength assignment heuristics and compared their throughput performance. We also included preliminary results of impact of the cascaded mode conversion constraint on network throughput. Datacenter and high performance computing networks share a number of common performance goals. Another highly efficient adaptive mode wavelength- routing algorithm is presented over OBS networks to improve throughput of these networks. The effectiveness of the proposed model has been validated by extensive simulation results.In order to optimize bandwidth and maximize throughput of datacenters, an extension of TCP called multipath-TCP (MPTCP) has been evaluated over an OBS network using dense interconnect datacenter topologies. We have proposed a service differentiation scheme using MPTCP over OBS for datacenter traffic. The scheme is evaluated over mixed workload traffic model of datacenters and is shown to provide tangible service differentiation between flows of different priority levels. An adaptive QoS differentiation architecture is proposed for software defined optical datacenter networks using MPTCP over OBS. This scheme prioritizes flows based on current network state.
Show less - Date Issued
- 2015
- Identifier
- CFE0005721, ucf:50146
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005721
- Title
- Mirrors and Vanities.
- Creator
-
Salas, Leslie, Rushin, Patrick, Poissant, David, Bartkevicius, Jocelyn, University of Central Florida
- Abstract / Description
-
"Mirrors and Vanities" is a multi-modal collection which showcases the diversity of working in long and short storytelling forms. Featured in this thesis are fiction, nonfiction, graphic narrative, and screenplay.Using unconventional approaches to storytelling in order to achieve emotional resonance with the audience while maintaining high standards for craft, these stories and essays explore the costs inherent to the subtle nuances of interpersonal relationships. The fiction focuses on the...
Show more"Mirrors and Vanities" is a multi-modal collection which showcases the diversity of working in long and short storytelling forms. Featured in this thesis are fiction, nonfiction, graphic narrative, and screenplay.Using unconventional approaches to storytelling in order to achieve emotional resonance with the audience while maintaining high standards for craft, these stories and essays explore the costs inherent to the subtle nuances of interpersonal relationships. The fiction focuses on the complications of characters keeping secrets. A husband discovers the truth behind his wife's miscarriage. A girl visits her fianc(&)#233; in purgatory. A boy crosses a line and loses his best friend. Meanwhile, the nonfiction centers on self-discovery and gender roles associated with power struggles. A schizophrenic threatens to ruin my mother's wedding. I rediscover my relationship with my father through food writing. Sword-work teaches me to fail and succeed at making martial art. The title work of the thesis is a collaged story highlighting the tribulations of a physicist fixated on recovering his lost love by manipulating the multiverse. The multi-modal format implicates the nebulosity of physics theories and how different aspects of the narrative can be presented in various formats to best suit the nature of the storytelling.Through the interactions of characters in mundane and extraordinary circumstances, the works in this thesis examine the consequences of choice, the contrast between reality and expectation, coming of age, and the Truth of narrative.
Show less - Date Issued
- 2013
- Identifier
- CFE0004745, ucf:49789
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004745
