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(21 - 31 of 31)
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- Title
- INVESTIGATION OF DAMAGE DETECTION METHODOLOGIES FOR STRUCTURAL HEALTH MONITORING.
- Creator
-
Gul, Mustafa, Catbas, F. Necati, University of Central Florida
- Abstract / Description
-
Structural Health Monitoring (SHM) is employed to track and evaluate damage and deterioration during regular operation as well as after extreme events for aerospace, mechanical and civil structures. A complete SHM system incorporates performance metrics, sensing, signal processing, data analysis, transmission and management for decision-making purposes. Damage detection in the context of SHM can be successful by employing a collection of robust and practical damage detection methodologies...
Show moreStructural Health Monitoring (SHM) is employed to track and evaluate damage and deterioration during regular operation as well as after extreme events for aerospace, mechanical and civil structures. A complete SHM system incorporates performance metrics, sensing, signal processing, data analysis, transmission and management for decision-making purposes. Damage detection in the context of SHM can be successful by employing a collection of robust and practical damage detection methodologies that can be used to identify, locate and quantify damage or, in general terms, changes in observable behavior. In this study, different damage detection methods are investigated for global condition assessment of structures. First, different parametric and non-parametric approaches are re-visited and further improved for damage detection using vibration data. Modal flexibility, modal curvature and un-scaled flexibility based on the dynamic properties that are obtained using Complex Mode Indicator Function (CMIF) are used as parametric damage features. Second, statistical pattern recognition approaches using time series modeling in conjunction with outlier detection are investigated as a non-parametric damage detection technique. Third, a novel methodology using ARX models (Auto-Regressive models with eXogenous output) is proposed for damage identification. By using this new methodology, it is shown that damage can be detected, located and quantified without the need of external loading information. Next, laboratory studies are conducted on different test structures with a number of different damage scenarios for the evaluation of the techniques in a comparative fashion. Finally, application of the methodologies to real life data is also presented along with the capabilities and limitations of each approach in light of analysis results of the laboratory and real life data.
Show less - Date Issued
- 2009
- Identifier
- CFE0002830, ucf:48069
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002830
- Title
- The Frequency of the Twelve Verb Tenses in History Papers Written by University Native Writers.
- Creator
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Qahtani, Bushra, Folse, Keith, Young, Beth, Fernandez-Rubiera, Francisco, University of Central Florida
- Abstract / Description
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Due to the variety and complexity of verb tenses in English, English as a Second Language (ESL) / English as a Foreign Language (EFL) learners often experience difficulty in mastering English verb tense system. This corpus-based study was conducted to ascertain the most frequently used verb tenses by English native speakers (NSs), specifically in their academic writing in a history course. As this study aimed to examine the naturally-occurring language produced by NSs, specifically in their...
Show moreDue to the variety and complexity of verb tenses in English, English as a Second Language (ESL) / English as a Foreign Language (EFL) learners often experience difficulty in mastering English verb tense system. This corpus-based study was conducted to ascertain the most frequently used verb tenses by English native speakers (NSs), specifically in their academic writing in a history course. As this study aimed to examine the naturally-occurring language produced by NSs, specifically in their academic writing, an original corpus of 101,713 words was assembled. The corpus consisted of 130 research papers written by 65 students. The corpus was analyzed, targeting certain linguistic items: the twelve verb tenses, modals, perfect modals, and imperatives. These targets were highlighted using a code-coloring method. Then, the items were calculated using Microsoft Excel. Excel calculations revealed the number of occurrences of each of the verb tenses, modals, perfect modals, and imperatives that was utilized in the corpus. The results revealed that the simple past tense was predominant, followed by the simple present tenses. Modals came third, as they occurred more frequently than any of the other verb tenses. The remaining targets had percentages ranging between 1.62% and zero. These findings could contribute in developing the methodology of teaching verb tenses to ESL/EFL learners in a way that reinforces their comprehension of the most important and most common items. In addition, this information is very important for materials designers and curriculum professionals.
Show less - Date Issued
- 2017
- Identifier
- CFE0007293, ucf:52150
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007293
- Title
- TEXT VERSUS VERBAL REAL-TIME FEEDBACK DURING SIMULATION-BASED TRAINING OF HIGHER-ORDER COGNITIVE SKILLS.
- Creator
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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.
Show less - Date Issued
- 2010
- Identifier
- CFE0003555, ucf:48915
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003555
- Title
- Optimal Switch Timing for Piezoelectric-Based Semi-Active Vibration Reduction Techniques.
- Creator
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Kelley, Christopher, Kauffman, Jeffrey, Das, Tuhin, Xu, Yunjun, University of Central Florida
- Abstract / Description
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Semi-active vibration reduction techniques switch a piezoelectric transducer between an open circuit and a shunt circuit in a way that reduces vibration. The steady-state vibration amplitude is reduced by exploiting the change in stiffness between states, manipulating the converted electrical energy, or both. Semi-active techniques typically require four switches per vibration cycle. Control laws such as state switching and synchronized switch damping require switches to occur at every...
Show moreSemi-active vibration reduction techniques switch a piezoelectric transducer between an open circuit and a shunt circuit in a way that reduces vibration. The steady-state vibration amplitude is reduced by exploiting the change in stiffness between states, manipulating the converted electrical energy, or both. Semi-active techniques typically require four switches per vibration cycle. Control laws such as state switching and synchronized switch damping require switches to occur at every displacement extrema. Due to the complexity of analyzing a system with discrete switches, these control laws were developed based on intuition. The few analyses that attempt to determine an optimal switching law mathematically only evaluate the system at resonance. This thesis investigates the effects of switch timing on vibration reduction and the frequency dependence of the optimal switch timing control law. Regardless of the switch timing, sensing uncertainties, noise, and modeling errors can cause the switches to occur away from the designed moment. Thus, this work also quantifies the expected degradation in vibration reduction performance due to variations in the designed switch time. Experimental, numerical, and analytical solutions agree that the optimal switch timing of these semi-active techniques depends on frequency. A closed-form solution for the optimal switch timing is derived in terms of well-known, non-dimensional parameters.
Show less - Date Issued
- 2016
- Identifier
- CFE0006336, ucf:51555
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006336
- Title
- A Multimedia Approach to Game-Based Training: Exploring the Effects of the Modality and Temporal Contiguity Principles on Learning in a Virtual Environment.
- Creator
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Serge, Stephen, Mouloua, Mustapha, Bohil, Corey, Bowers, Clint, Priest Walker, Heather, University of Central Florida
- Abstract / Description
-
There is an increasing interest in using video games as a means to deliver training to individuals learning new skills or tasks. However, current research lacks a clear method of developing effective instructional material when these games are used as training tools and explaining how gameplay may affect learning. The literature contains multiple approaches to training and GBT but generally lacks a foundational-level and theoretically relevant approach to how people learn specifically from...
Show moreThere is an increasing interest in using video games as a means to deliver training to individuals learning new skills or tasks. However, current research lacks a clear method of developing effective instructional material when these games are used as training tools and explaining how gameplay may affect learning. The literature contains multiple approaches to training and GBT but generally lacks a foundational-level and theoretically relevant approach to how people learn specifically from video games and how to design instructional guidance within these gaming environments. This study investigated instructional delivery within GBT. Video games are a form of multimedia, consisting of both imagery and sounds. The Cognitive Theory of Multimedia Learning (CTML; Mayer 2005) explicitly describes how people learn from multimedia information, consisting of a combination of narration (words) and animation (pictures). This study empirically examined the effects of the modality and temporal contiguity principles on learning in a game-based virtual environment. Based on these principles, it was hypothesized that receiving either voice or embedded training would result in better performance on learning measures. Additionally, receiving a combination of voice and embedded training would lead to better performance on learning measures than all other instructional conditions.A total of 128 participants received training on the role and procedures related to the combat lifesaver (-) a non-medical soldier who receives additional training on combat-relevant lifesaving medical procedures. Training sessions involved an instructional presentation manipulated along the modality (voice or text) and temporal contiguity (embedded in the game or presented before gameplay) principles. Instructional delivery was manipulated in a 2x2 between-subjects design with four instructional conditions: Upfront-Voice, Upfront-Text, Embedded-Voice, and Embedded-Text. Results indicated that: (1) upfront instruction led to significantly better retention performance than embedded instructional regardless of delivery modality; (2) receiving voice-based instruction led to better transfer performance than text-based instruction regardless of presentation timing; (3) no differences in performance were observed on the simple application test between any instructional conditions; and (4) a significant interaction of modality-by-temporal contiguity was obtained. Simple effects analysis indicated differing effects along modality within the embedded instruction group, with voice recipients performing better than text (p = .012). Individual group comparisons revealed that the upfront-voice group performed better on retention than both embedded groups (p = .006), the embedded-voice group performed better on transfer than the upfront text group (p = .002), and the embedded-voice group performed better on the complex application test than the embedded-text group (p =.012). Findings indicated partial support for the application of the modality and temporal contiguity principles of CTML in interactive GBT. Combining gameplay (i.e., practice) with instructional presentation both helps and hinders working memory's ability to process information. Findings also explain how expanding CTML into game-based training may fundamentally change how a person processes information as a function of the specific type of knowledge being taught. Results will drive future systematic research to test and determine the most effective means of designing instruction for interactive GBT. Further theoretical and practical implications will be discussed.
Show less - Date Issued
- 2014
- Identifier
- CFE0005548, ucf:50271
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005548
- Title
- Load Estimation, Structural Identification and Human Comfort Assessment of Flexible Structures.
- Creator
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Celik, Ozan, Catbas, Necati, Yun, Hae-Bum, Makris, Nicos, Kauffman, Jeffrey L., University of Central Florida
- Abstract / Description
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Stadiums, pedestrian bridges, dance floors, and concert halls are distinct from other civil engineering structures due to several challenges in their design and dynamic behavior. These challenges originate from the flexible inherent nature of these structures coupled with human interactions in the form of loading. The investigations in past literature on this topic clearly state that the design of flexible structures can be improved with better load modeling strategies acquired with reliable...
Show moreStadiums, pedestrian bridges, dance floors, and concert halls are distinct from other civil engineering structures due to several challenges in their design and dynamic behavior. These challenges originate from the flexible inherent nature of these structures coupled with human interactions in the form of loading. The investigations in past literature on this topic clearly state that the design of flexible structures can be improved with better load modeling strategies acquired with reliable load quantification, a deeper understanding of structural response, generation of simple and efficient human-structure interaction models and new measurement and assessment criteria for acceptable vibration levels. In contribution to these possible improvements, this dissertation taps into three specific areas: the load quantification of lively individuals or crowds, the structural identification under non-stationary and narrowband disturbances and the measurement of excessive vibration levels for human comfort. For load quantification, a computer vision based approach capable of tracking both individual and crowd motion is used. For structural identification, a noise-assisted Multivariate Empirical Mode Decomposition (MEMD) algorithm is incorporated into the operational modal analysis. The measurement of excessive vibration levels and the assessment of human comfort are accomplished through computer vision based human and object tracking, which provides a more convenient means for measurement and computation. All the proposed methods are tested in the laboratory environment utilizing a grandstand simulator and in the field on a pedestrian bridge and on a football stadium. Findings and interpretations from the experimental results are presented. The dissertation is concluded by highlighting the critical findings and the possible future work that may be conducted.
Show less - Date Issued
- 2017
- Identifier
- CFE0006863, ucf:51752
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006863
- Title
- STRUCTURAL CONDITION ASSESSMENT OF PRESTRESSED CONCRETE TRANSIT GUIDEWAYS.
- Creator
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Shmerling, Robert, Catbas, F. Necati, University of Central Florida
- Abstract / Description
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Objective condition assessment is essential to make better decisions for safety and serviceability of existing civil infrastructure systems. This study explores the condition of an existing transit guideway system that has been in service for thirty-five years. The structural system is composed of six-span continuous prestressed concrete bridge segments. The overall transit system incorporates a number of continuous bridges which share common design details, geometries, and loading conditions...
Show moreObjective condition assessment is essential to make better decisions for safety and serviceability of existing civil infrastructure systems. This study explores the condition of an existing transit guideway system that has been in service for thirty-five years. The structural system is composed of six-span continuous prestressed concrete bridge segments. The overall transit system incorporates a number of continuous bridges which share common design details, geometries, and loading conditions. The original analysis is based on certain simplifying assumptions such as rigid behavior over supports and simplified tendon/concrete/steel plate interaction. The current objective is to conduct a representative study for a more accurate understanding of the structural system and its behavior. The scope of the study is to generate finite element models (FEMs) to be used in static and dynamic parameter sensitivity studies, as well load rating and reliability analysis of the structure. The FEMs are used for eigenvalue analysis and simulations. Parameter sensitivity studies consider the effect of changing critical parameters, including material properties, prestress loss, and boundary and continuity conditions, on the static and dynamic structural response. Load ratings are developed using an American Association for State Highway Transportation Officials Load and Resistance Factor Rating (AASHTO LRFR) approach. The reliability of the structural system is evaluated based on the data obtained from various finite element models. Recommendations for experimental validation of the FEM are presented. This study is expected to provide information to make better decisions for operations, maintenance and safety requirements; to be a benchmark for future studies, to establish a procedure and methodology for structural condition assessment, and to contribute to the general research body of knowledge in condition assessment and structural health monitoring.
Show less - Date Issued
- 2005
- Identifier
- CFE0000658, ucf:46520
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000658
- Title
- The Frequency of the Passive Voice in Freshman Academic Books.
- Creator
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Moreb, Basma, Folse, Keith, Mihai, Florin, Young, Beth, University of Central Florida
- Abstract / Description
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The use of passive voice has long been an area of difficulty for English learners. Celce-Murcia (&) Larsen-Freeman (2015) noted that it is learning when to use the English passive that presents the greatest long-term challenge to ESL/EFL students(") (p. 352). Because textbooks are a source of language input for English learners, this study investigated the frequency of passive voice verbs in samples from four academic textbooks in courses commonly taken by freshmen. The study also examined...
Show moreThe use of passive voice has long been an area of difficulty for English learners. Celce-Murcia (&) Larsen-Freeman (2015) noted that it is learning when to use the English passive that presents the greatest long-term challenge to ESL/EFL students(") (p. 352). Because textbooks are a source of language input for English learners, this study investigated the frequency of passive voice verbs in samples from four academic textbooks in courses commonly taken by freshmen. The study also examined whether there are significant differences between the frequencies by textbook. The data was collected from four General Education Plan (GEP) subject textbooks used in freshman classes at a large metropolitan university in the southeastern United States, namely English composition, history, psychology, and biology. The data was then compiled into a corpus of approximately 20,000 words created specifically for the current study, with 5,000 words randomly and sequentially selected from each of the four textbooks. The study utilized a table created by Folse (2009) to analyze differences between the basic passive voice tenses found in the textbooks. The study examined the be-passives, get-passives, and have-passives and their frequency in different tenses. The findings revealed that passive voice occurred in academic textbooks with an overall frequency of 7.06% (of all conjugated verbs). The results also found significant differences between the academic genres (p (<) 0.05). In this particular corpus, passive voice occurred more in biology than in the other subjects. Therefore, the results of the study indicated a need to explicitly teach the basic be-passive voice to English language learners to all English learners, but teachers also need to be especially aware that certain university subjects (e.g., biology) use more passive voice verb forms than others.
Show less - Date Issued
- 2016
- Identifier
- CFE0006695, ucf:51929
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006695
- Title
- MULTI-MODAL READING FOR LOW LEVEL READERS.
- Creator
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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
- Explicit Feedback Within Game-Based Training: Examining the Influence of Source Modality Effects on Interaction.
- Creator
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Goldberg, Benjamin, Bowers, Clint, Cannon-Bowers, Janis, Kincaid, John, McDaniel, Thomas, Sottilare, Robert, University of Central Florida
- Abstract / Description
-
This research aims to enhance Simulation-Based Training (SBT) applications to support training events in the absence of live instruction. The overarching purpose is to explore available tools for integrating intelligent tutoring communications in game-based learning platforms and to examine theory-based techniques for delivering explicit feedback in such environments. The primary tool influencing the design of this research was the Generalized Intelligent Framework for Tutoring (GIFT), a...
Show moreThis research aims to enhance Simulation-Based Training (SBT) applications to support training events in the absence of live instruction. The overarching purpose is to explore available tools for integrating intelligent tutoring communications in game-based learning platforms and to examine theory-based techniques for delivering explicit feedback in such environments. The primary tool influencing the design of this research was the Generalized Intelligent Framework for Tutoring (GIFT), a modular domain-independent architecture that provides the tools and methods to author, deliver, and evaluate intelligent tutoring technologies within any training platform. Influenced by research surrounding Social Cognitive Theory and Cognitive Load Theory, the resulting experiment tested varying approaches for utilizing an Embodied Pedagogical Agent (EPA) to function as a tutor during interaction in a game-based environment. Conditions were authored to assess the tradeoffs between embedding an EPA directly in a game, embedding an EPA in GIFT's browser-based Tutor-User Interface (TUI), or using audio prompts alone with no social grounding.The resulting data supports the application of using an EPA embedded in GIFT's TUI to provide explicit feedback during a game-based learning event. Analyses revealed conditions with an EPA situated in the TUI to be as effective as embedding the agent directly in the game environment. This inference is based on evidence showing reliable differences across conditions on the metrics of performance and self-reported mental demand and feedback usefulness items. This research provides source modality tradeoffs linked to tactics for relaying training relevant explicit information to a user based on real-time performance in a game.
Show less - Date Issued
- 2013
- Identifier
- CFE0004850, ucf:49696
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004850
- 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
