Current Search: Transformer (x)
View All Items
(41 - 58 of 58)
Pages
- Title
- Inversion of the Broken Ray Transform.
- Creator
-
Krylov, Roman, Katsevich, Alexander, Tamasan, Alexandru, Nashed, M, Zeldovich, Boris, University of Central Florida
- Abstract / Description
-
The broken ray transform (BRT) is an integral of a functionalong a union of two rays with a common vertex.Consider an X-ray beam scanning an object of interest.The ray undergoes attenuation and scatters in all directions inside the object.This phenomena may happen repeatedly until the photons either exit the object or are completely absorbed.In our work we assume the single scattering approximation when the intensity of the raysscattered more than once is negligibly small.Among all paths that...
Show moreThe broken ray transform (BRT) is an integral of a functionalong a union of two rays with a common vertex.Consider an X-ray beam scanning an object of interest.The ray undergoes attenuation and scatters in all directions inside the object.This phenomena may happen repeatedly until the photons either exit the object or are completely absorbed.In our work we assume the single scattering approximation when the intensity of the raysscattered more than once is negligibly small.Among all paths that the scattered rays travel inside the object we pick the one that isa union of two segments with one common scattering point.The intensity of the ray which traveled this path and exited the object can be measured by a collimated detector.The collimated detector is able to measure the intensity of X-rays from the selected direction.The logarithm of such a measurement is the broken ray transform of the attenuation coefficientplus the logarithm of the scattering coefficient at the scattering point (vertex)and a known function of the scattering angle.In this work we consider the reconstruction of X-ray attenuation coefficient distributionin a plane from the measurements on two or three collimated detector arrays.We derive an exact local reconstruction formula for three flat collimated detectorsor three curved or pin-hole collimated detectors.We obtain a range condition for the case of three curved or pin-hole detectors and provide a special caseof the range condition for three flat detectors.We generalize the reconstruction formula to four and more detectors and find anoptimal set of parameters that minimize noise in the reconstruction.We introduce a more accurate scattering model which takes into accountenergy shifts due to the Compton effect, derive an exact reconstruction formula and develop an iterativereconstruction method for the energy-dependent case.To solve the problem we assume that the radiation source is monoenergeticand the dependence of the attenuation coefficient on energy is linearon an energy interval from the minimal to the maximal scattered energy. %initial radiation energy.We find the parameters of the linear dependence of the attenuation on energy as a function of a pointin the reconstruction plane.
Show less - Date Issued
- 2014
- Identifier
- CFE0005514, ucf:50324
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005514
- Title
- COMMISSIONING OF AN ARC-MELTING / VACUUM QUENCH FURNACE FACILITY FOR FABRICATION OF NI-TI-FE SHAPE MEMORY ALLOYS, AND THEIR CHARACTERIZATION.
- Creator
-
Singh, Jagat, Vaidyanathan, Raj, University of Central Florida
- Abstract / Description
-
Shape memory alloys when deformed can produce strains as high as 8%. Heating results in a phase transformation and associated recovery of all the accumulated strain, a phenomenon known as shape memory. This strain recovery can occur against large forces, resulting in their use as actuators. The goal of this project is to lower the operating temperature range of shape memory alloys in order for them to be used in cryogenic switches, seals, valves, fluid-line repair and self-healing gaskets for...
Show moreShape memory alloys when deformed can produce strains as high as 8%. Heating results in a phase transformation and associated recovery of all the accumulated strain, a phenomenon known as shape memory. This strain recovery can occur against large forces, resulting in their use as actuators. The goal of this project is to lower the operating temperature range of shape memory alloys in order for them to be used in cryogenic switches, seals, valves, fluid-line repair and self-healing gaskets for space related technologies. The Ni-Ti-Fe alloy system, previously used in Grumman F-14 aircrafts and activated at 120 K, is further developed through arc-melting a range of compositions and subsequent thermo-mechanical processing. A controlled atmosphere arc-melting facility and vertical vacuum quench furnace facility was commissioned to fabricate these alloys. The facility can create a vacuum of 10-7 Torr and heat treat samples up to 977 °C. High purity powders of Ni, Ti and Fe in varying ratios were mixed and arc-melted into small buttons weighing 0.010 kg to 0.025 kg. The alloys were subjected to solutionizing and aging treatments. A combination of rolling, electro-discharge machining and low-speed cutting techniques were used to produce strips. Successful rolling experiments highlighted the workability of these alloys. The shape memory effect was successfully demonstrated at liquid nitrogen temperatures through a constrained recovery experiment that generated stresses of over 40 MPa. Differential scanning calorimetry (DSC) and a dilatometry setup was used to characterize the fabricated materials and determine relationships between composition, thermo-mechanical processing parameters and transformation temperatures.
Show less - Date Issued
- 2004
- Identifier
- CFE0000308, ucf:46320
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000308
- Title
- THE EFFECT OF WEIGHT AND SIZE ON MENTAL ROTATION.
- Creator
-
Furtak, Luke, Sims, Valerie, University of Central Florida
- Abstract / Description
-
Shepard and Metzler (1971) argued that mental rotation is analogous to the real world in that people imagine the rotation of an object as if it were being physically rotated. This study tested this assertion by exposing participants to physical shapes that increased in size and weight. Participants interacted with blocks designed after Shepard and Metzler mental rotation size that differed in size and weight then performed subsequent mental rotation. We found no difference in reaction time...
Show moreShepard and Metzler (1971) argued that mental rotation is analogous to the real world in that people imagine the rotation of an object as if it were being physically rotated. This study tested this assertion by exposing participants to physical shapes that increased in size and weight. Participants interacted with blocks designed after Shepard and Metzler mental rotation size that differed in size and weight then performed subsequent mental rotation. We found no difference in reaction time but found that increased size reduced accuracy. We discuss the implications of this study as they pertain to embodied cognition.
Show less - Date Issued
- 2014
- Identifier
- CFH0004711, ucf:45399
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004711
- Title
- Investigating changes in quiescence in oral and esophageal epithelium in response to injury.
- Creator
-
Rothaus, Alexandra, Andl, Claudia, Chakrabarti, Ratna, Singla, Dinender, University of Central Florida
- Abstract / Description
-
More than 570,000 new cases of esophageal cancer are estimated to be diagnosed annually worldwide. Risk factors include gender, age, tobacco use and dietary habits leading to tissue injury and ultimately cancer. While prognoses for other cancers have improved, the 5-year survival for patients with esophageal cancer is only 20%. During the repair process, cell proliferation is increased and is associated with inflammation. Slow-cycling lifetime residential stem cells, called quiescent cells,...
Show moreMore than 570,000 new cases of esophageal cancer are estimated to be diagnosed annually worldwide. Risk factors include gender, age, tobacco use and dietary habits leading to tissue injury and ultimately cancer. While prognoses for other cancers have improved, the 5-year survival for patients with esophageal cancer is only 20%. During the repair process, cell proliferation is increased and is associated with inflammation. Slow-cycling lifetime residential stem cells, called quiescent cells, facilitate repair but are thought to accumulate mutations during DNA replication eventually giving rise to cancer. We hypothesize that esophageal stem cells become activated upon injury and are regulated by Transforming Growth Factor beta 1 (TGF?1), a known regulator of cell proliferation and differentiation. We established an in vitro model of quiescence using normal esophageal epithelial (STR) and oral (OKF6) cells treated with recombinant human TGF?1. Flow cytometry showed increases in cells arrested in G1/G0 phase of the cell cycle in TGF?1 treated cells for both cell lines (STR p(<)0.01, OKF6 p(<)0.05). EdU (5-ethynyl-2'-deoxyuridine) positive recovery cells indicated quiescence in both cell lines (p(<)0.01). Analysis of TGF?1 regulation of putative stem cell markers via western blot and qRT-PCR showed increases in ITGB1, PDPN and K15 as well as XPC, and MeCP2 in treated cells. To apply our in vitro findings, we performed immunohistochemistry staining on tissue microarrays. Proliferation marker Ki67 increased in disease progression from normal to inflammation to hyperplasia (p(<)0.001) while TGF?1 target markers decrease. Our data indicate that the onset of cancer-associated inflammation correlates with the loss of TGF?1 mediated stemness markers and increased basal proliferation suggesting cancer is a stem cell disease.
Show less - Date Issued
- 2019
- Identifier
- CFE0007903, ucf:52754
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007903
- Title
- ADDRESSING THE ACHIEVEMENT GAP AND DISPROPORTIONALITY THROUGH THE USE OF CULTURALLY RESPONSIVE TEACHING PRACTICES.
- Creator
-
Griner, Angela, Lue Stewart, Martha, University of Central Florida
- Abstract / Description
-
Culturally responsive teaching practices in schools and classrooms have been shown to be an effective means of addressing the achievement gap, as well as the disproportionate representation of racially, culturally, ethnically, and linguistically diverse students in programs serving students with special needs. While there has been a recent influx in research discussing these issues, teachers and school staff lack clear examples and tools for best practices that will aid them in addressing the...
Show moreCulturally responsive teaching practices in schools and classrooms have been shown to be an effective means of addressing the achievement gap, as well as the disproportionate representation of racially, culturally, ethnically, and linguistically diverse students in programs serving students with special needs. While there has been a recent influx in research discussing these issues, teachers and school staff lack clear examples and tools for best practices that will aid them in addressing the achievement gap and disproportionality effectively within their schools. Conducted in three phases, this research provides a framework for developing, implementing, and evaluating a culturally responsive tool for schools and school staff in order to impact beliefs and practices related to culturally responsive teaching, leading to the enhanced learning outcomes of all students.
Show less - Date Issued
- 2011
- Identifier
- CFE0003880, ucf:48759
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003880
- Title
- INTERNATIONAL SPACE STATION REMOTE SENSING POINTING ANALYSIS.
- Creator
-
Jacobson, Craig, Leonessa, Alexander, University of Central Florida
- Abstract / Description
-
This paper analyzes the geometric and disturbance aspects of utilizing the International Space Station for remote sensing of earth targets. The proposed instrument is SHORE (Station High-Sensitivity Ocean Research Experiment), a multi-band optical spectrometer with 15 m pixel resolution. The analysis investigates the contribution of the error effects to the quality of data collected by the instrument. The analysis begins with the discussion of the coordinate systems involved and then...
Show moreThis paper analyzes the geometric and disturbance aspects of utilizing the International Space Station for remote sensing of earth targets. The proposed instrument is SHORE (Station High-Sensitivity Ocean Research Experiment), a multi-band optical spectrometer with 15 m pixel resolution. The analysis investigates the contribution of the error effects to the quality of data collected by the instrument. The analysis begins with the discussion of the coordinate systems involved and then conversion from the target coordinate system to the instrument coordinate system. Next the geometry of remote observations from the Space Station is investigated including the effects of the instrument location in Space Station and the effects of the line of sight to the target. The disturbance and error environment on Space Station is discussed covering factors contributing to drift and jitter, accuracy of pointing data and target and instrument accuracies. Finally, there is a brief discussion of image processing to address any post error correction options.
Show less - Date Issued
- 2005
- Identifier
- CFE0000855, ucf:46661
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000855
- Title
- Spectral properties of the finite Hilbert transform on two adjacent intervals via the method of Riemann-Hilbert problem.
- Creator
-
Blackstone, Elliot, Tovbis, Alexander, Katsevich, Alexander, Tamasan, Alexandru, Pang, Sean, University of Central Florida
- Abstract / Description
-
In this dissertation, we study a self-adjoint integral operator $\hat{K}$ which is defined in terms of finite Hilbert transforms on two adjacent intervals. These types of transforms arise when one studies the interior problem of tomography. The operator $\hat{K}$ possesses a so-called ``integrable kernel'' and it is known that the spectral properties of $\hat{K}$ are intimately related to a $2\times2$ matrix function $\Gamma(z;\lambda)$ which is the solution to a particular Riemann-Hilbert...
Show moreIn this dissertation, we study a self-adjoint integral operator $\hat{K}$ which is defined in terms of finite Hilbert transforms on two adjacent intervals. These types of transforms arise when one studies the interior problem of tomography. The operator $\hat{K}$ possesses a so-called ``integrable kernel'' and it is known that the spectral properties of $\hat{K}$ are intimately related to a $2\times2$ matrix function $\Gamma(z;\lambda)$ which is the solution to a particular Riemann-Hilbert problem (in the $z$ plane). We express $\Gamma(z;\lambda)$ explicitly in terms of hypergeometric functions and find the small $\lambda$ asymptotics of $\Gamma(z;\lambda)$. This asymptotic analysis is necessary for the spectral analysis of the finite Hilbert transform on multiple adjacent intervals. We show that $\Gamma(z;\lambda)$ also has a jump in the $\lambda$ plane which allows us to compute the jump of the resolvent of $\hat{K}$. This jump is an important step in showing that the finite Hilbert transforms has simple and purely absolutely continuous spectrum. The well known spectral theory now allows us to construct unitary operators which diagonalize the finite Hilbert transforms. Lastly, we mention some future directions which include the many interval scenario and a bispectral property of $\hat{K}$.
Show less - Date Issued
- 2019
- Identifier
- CFE0007602, ucf:52527
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007602
- Title
- A Crack in Everything.
- Creator
-
Hoffman, Jeffrey, Isenhour, David, Poindexter, Carla, Kim, Joo, University of Central Florida
- Abstract / Description
-
Contained herein is a close examination of self-awareness and self-portraiture as it applies to the works of artist Jeffrey Hoffman. Water, frozen into various forms and combined with natural elements of wood, slowly melt over an indeterminable amount of time, each droplet documented as the process transforms the elements. Through this process, we see change. We see time. We see truth. This documentation of change and time through natural elements is where the artwork comes full circle....
Show moreContained herein is a close examination of self-awareness and self-portraiture as it applies to the works of artist Jeffrey Hoffman. Water, frozen into various forms and combined with natural elements of wood, slowly melt over an indeterminable amount of time, each droplet documented as the process transforms the elements. Through this process, we see change. We see time. We see truth. This documentation of change and time through natural elements is where the artwork comes full circle. Working with new media to explore man's interconnectivity to life, energy, and the cosmos, he produces time based installations, photographs, videos, and sculptures that serve as both existential metaphors and Tantric symbols. With the use of digital cameras and video, a record is created by which the disintegration which occurs from the unseen forces of gravity, heat and time upon sculptures made from natural elements and ice is examined. In its sculptural form, his work can be categorized as Installation art and Performance art due to its evolving nature. Each piece is intended to either change over time or to have that change halted by another temporal force like that of flowing electricity. The possibility of allowing varying levels of self-awareness to emerge through self portraiture is also examined. The existential, as well as the metaphysical, can be present in a physical form when the form is imbued with evidence of an evolutionary process. In many ways, the work serves as a self portrait. It is a means for Hoffman to examine his own existentialism as a student of the modern western world and life.
Show less - Date Issued
- 2012
- Identifier
- CFE0004242, ucf:49518
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004242
- Title
- 7: AN INTERACTIVE INSTALLATION; EXPLORATIONS IN THE DIGITAL, THE SPIRITUAL, AND THE UNCANNY.
- Creator
-
Lewter, Bradley, Peters, Phil, University of Central Florida
- Abstract / Description
-
This thesis explores the application of digital technologies in the creation of visionary or transformative artwork. The installation emphasizes number, color, symmetry, and the human form to create symbolic compositions patterned after ancient archetypes. Background research was done to inform the work through studies of the principles of visionary and transformative artwork as practiced by Ernst Fuchs, De Es Schwertberger, and Alex Grey. Connections between art and spirituality as explained...
Show moreThis thesis explores the application of digital technologies in the creation of visionary or transformative artwork. The installation emphasizes number, color, symmetry, and the human form to create symbolic compositions patterned after ancient archetypes. Background research was done to inform the work through studies of the principles of visionary and transformative artwork as practiced by Ernst Fuchs, De Es Schwertberger, and Alex Grey. Connections between art and spirituality as explained by Kandinsky were studied to augment these principles. The sequence of artwork within the installation is comprised of both digital paintings and interactive triptych panels. To convey a sense of the mystical or sacred, the Rothko Chapel was used to inform the installation and serve as an artistic precedent. As the interactive work is created using realistically-modeled, computer generated characters, special consideration was given to understanding the "uncanny valley" and its potential effect in the interpretation of the installation. Interactivity is achieved through the use of ultrasonic sensors and Arduino prototyping boards.
Show less - Date Issued
- 2010
- Identifier
- CFE0003314, ucf:48487
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003314
- Title
- WRITE THE COMMUNITY: THE EFFECTS OF SERVICE-LEARNING PARTICIPATION ON SEVEN UNIVERSITY CREATIVE WRITING STUDENTS.
- Creator
-
Hodges, Lauren, Kaplan, Jeffrey, University of Central Florida
- Abstract / Description
-
Research in higher education service-learning suggests that there is a positive relationship between service-learning and student learning outcomes as well as a positive relationship between students' interactions with the "real world" through service-learning and the effects of these experiences on deepening students' knowledge in their disciplines. Recent studies have established this positive relationship between service-learning and university composition and literature students. However,...
Show moreResearch in higher education service-learning suggests that there is a positive relationship between service-learning and student learning outcomes as well as a positive relationship between students' interactions with the "real world" through service-learning and the effects of these experiences on deepening students' knowledge in their disciplines. Recent studies have established this positive relationship between service-learning and university composition and literature students. However, aside from the existing literature on service-learning and composition and writing, there has been virtually no examination of the relationship between service-learning and creative writing. The purpose of this study was to investigate how seven creative writing students experienced the process of creative writing differently after engaging in service-learning in a creative writing course at a large, urban university in the southeastern United States and to determine if students experienced a transformative learning experience as indicated by Mezirow's (2000) transformational learning theory. This research study employed an instrumental narrative case study design to determine how seven university creative writing students experienced the process of creative writing differently after taking a creative writing course with an optional service-learning component. The results of the study indicated that service-learning invoked a transformative learning experience in these seven higher education creative writing students, each in different ways-some in their writing processes and writing content, some in how they reflected upon themselves and their writing in relation to the "outside world," and some in their sense of civic duty.
Show less - Date Issued
- 2011
- Identifier
- CFE0003988, ucf:48655
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003988
- Title
- DIFFRACTION STUDIES OF DEFORMATION IN SHAPE MEMORY ALLOYS AND SELECTED ENGINEERING COMPONENTS.
- Creator
-
RATHOD, CHANDRASEN, Vaidyanathan, Raj, University of Central Florida
- Abstract / Description
-
Deformation phenomena in shape memory alloys involve stress-, temperature-induced phase transformations and crystallographic variant conversion or reorientation, equivalent to a twinning operation. In near equiatomic NiTi, Ti rich compositions can exist near room temperature as a monoclinic B19' martensitic phase, which when deformed undergoes twinning resulting in strains as large as 8%. Upon heating, the martensite transforms to a cubic B2 austenitic phase, thereby recovering the strain and...
Show moreDeformation phenomena in shape memory alloys involve stress-, temperature-induced phase transformations and crystallographic variant conversion or reorientation, equivalent to a twinning operation. In near equiatomic NiTi, Ti rich compositions can exist near room temperature as a monoclinic B19' martensitic phase, which when deformed undergoes twinning resulting in strains as large as 8%. Upon heating, the martensite transforms to a cubic B2 austenitic phase, thereby recovering the strain and exhibiting the shape memory effect. Ni rich compositions on the other hand can exist near room temperature in the austenitic phase and undergo a reversible martensitic transformation on application of stress. Associated with this reversible martensitic transformation are macroscopic strains, again as large as 8%, which are also recovered and resulting in superelasticity. This work primarily focuses on neutron diffraction measurements during loading at the Los Alamos Neutron Science Center at Los Alamos National Laboratory. Three phenomena were investigated: First, the phenomena of hysteresis reduction and increase in linearity with increasing plastic deformation in superelastic NiTi. There is usually a hysteresis associated with the forward and reverse transformations in superelastic NiTi which translates to a hysteresis in the stress-strain curve during loading and unloading. This hysteresis is reduced in cold-worked NiTi and the macroscopic stress-strain response is more linear. This work reports on measurements during loading and unloading in plastically deformed (up to 11%) and cycled NiTi. Second, the tension-compression stress-strain asymmetry in martensitic NiTi. This work reports on measurements during tensile and compressive loading of polycrystalline shape-memory martensitic NiTi with no starting texture. Third, a heterogeneous stress-induced phase transformation in superelastic NiTi. Measurements were performed on a NiTi disc specimen loaded laterally in compression and associated with a macroscopically heterogeneous stress state. For the case of superelastic NiTi, the experiments related the macroscopic stress-strain behavior (from an extensometer or an analytical approach) with the texture, phase volume fraction and strain evolution (from neutron diffraction spectra). For the case of shape memory NiTi, the macroscopic connection was made with the texture and strain evolution due to twinning and elastic deformation in martensitic NiTi. In all cases, this work provided for the first time insight into atomic-scale phenomena such as mismatch accommodation and martensite variant selection. The aforementioned technique of neutron diffraction for mechanical characterization was also extended to engineering components and focused mainly on the determination of residual strains. Two samples were investigated and presented in this work; first, a welded INCONEL 718 NASA space shuttle flow liner was studied at 135 K and second, Ti-6Al-4V turbine blade components were investigated for Siemens Westinghouse Power Corporation. Lastly, also reported in this dissertation is a refinement of the methodology established in the author's masters thesis at UCF that used synchrotron x-ray diffraction during loading to study superelastic NiTi. The Los Alamos Neutron Science Center is a national user facility funded by the United States Department of Energy, Office of Basic Energy Sciences, under Contract No. W-7405-ENG-36. The work reported here was made possible by grants to UCF from NASA (NAG3-2751), NSF CAREER (DMR-0239512), Siemens Westinghouse Power Corporation and the Space Research Initiative.
Show less - Date Issued
- 2005
- Identifier
- CFE0000723, ucf:46608
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000723
- Title
- EDUCATIONAL VISION IN FLORIDA SCHOOL DISTRICTS: VISION ALIGNMENT AND LEADERSHIP STYLE.
- Creator
-
Sikkenga, Cindy, House, Jess, University of Central Florida
- Abstract / Description
-
The purpose of this study was to address a gap in the organizational leadership research related to the sharing, or alignment, of leadership vision across organizational levels, with a focus on educational vision alignment in Florida K-12 public school districts. The study also sought to determine to what extent, if any, there were differences among Florida school districts exhibiting different levels of educational vision alignment. The broad question addressed by the current research was...
Show moreThe purpose of this study was to address a gap in the organizational leadership research related to the sharing, or alignment, of leadership vision across organizational levels, with a focus on educational vision alignment in Florida K-12 public school districts. The study also sought to determine to what extent, if any, there were differences among Florida school districts exhibiting different levels of educational vision alignment. The broad question addressed by the current research was this: To what degree are the educational visions of superintendents and principals aligned within Florida K-12 public school districts? The following research questions further guided the study: 1. What common themes can be found in the published vision statements of the 67 Florida K-12 public school districts? 2. To what extent, if any, do Florida K-12 public school district superintendents and their respective principals agree with one another on the importance of the common themes found in Florida school districts' published vision statements? 3. What is the relationship, if any, between educational vision alignment levels in Florida K-12 public school districts and principals' perceptions of their superintendents' leadership styles? 4. To what extent, if any, are there differences among Florida K-12 public school districts exhibiting different levels of educational vision alignment? The Florida Educational Vision Questionnaire Superintendent Form (FEVQ-S), a researcher developed questionnaire, was administered to all 67 Florida K-12 public school district superintendents. With superintendent approval, two additional questionnaires were administered to a sample of 242 principals in 23 school districts. The Florida Educational Vision Questionnaire Principal Form (FEVQ-P) and the Multifactor Leadership Questionnaire Form 5X Rater (MLQ-5X) (Avolio, Bass, & Jung, 1999) were returned fully completed by 105 principals in 21 districts. A total of 81 principal responses in 20 districts were usable, yielding overall usable response rates of 29.9% (superintendents) and 33.5% (principals). Comparisons of FEVQ responses of superintendents and principals in each school district were made using a researcher developed measure, the Educational Vision Alignment Index (EVAI). Within each district, the EVAI was compared with the superintendent's leadership style as measured by the principals' responses to the MLQ-5X. School districts were then compared using data obtained from the FEVQ demographic items, the Florida School Indicators Report (FSIR) (FLDOE, 2003a), the 2004 School Grades by District Report (FLDOE, n.d.), and the online Florida Public School Superintendents report (FLDOE, 2005c). The FSIR contains data on district characteristics such as operating costs, per pupil expenditures, school staff composition, student membership, student mobility rates, student stability rates, and teacher descriptors. The 2004 School Grades by District report contains both the school grades for each district and the total number of schools per district. The Florida Public School Superintendents report contains general school district information and superintendent status (i.e., elected or appointed) information. Detailed data analyses related to each of the four research questions indicated that: 1. Several common themes can be found in the published vision statements of the 67 Florida K-12 public school districts, 2. Florida K-12 public school district superintendents and their respective principals agree with one another on the importance of some of these common themes, 3. Several relationships exist between the educational vision alignment levels in Florida K-12 public school districts and principals' perceptions of their superintendents' leadership styles, and 4. There are differences among Florida K-12 public school districts exhibiting different levels of educational vision alignment. The current study illustrated that in Florida K-12 public school districts whose superintendents were perceived to be transformational leaders, a strong alignment of educational vision between the superintendents and their principals was also apparent, particularly in those districts having elected superintendents. Using the two researcher developed tools, the Florida Educational Vision Questionnaire (FEVQ) and the Educational Vision Alignment Index (EVAI), it was shown that this alignment pertained to specific content items, or themes, derived from an analysis of the educational vision statements of the 67 Florida school districts. These results indicate that the current emphasis in Florida on the development of transformational leaders who are knowledgeable in techniques for developing and communicating shared visions is therefore warranted.
Show less - Date Issued
- 2006
- Identifier
- CFE0001349, ucf:46995
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001349
- Title
- The unheard voices of nontraditional students in Higher Education: Learning to become a student.
- Creator
-
Julio Maturana, Marcelo, Cintron Delgado, Rosa, Boote, David, Owens, J. Thomas, Guzman-Valenzuela, Carolina, Rivera, Fernando, University of Central Florida
- Abstract / Description
-
This study explores the lived experiences of older students who work and have family responsibilities while attending an undergraduate program full-time. Research indicates that this segment of the student population is the only one that is growing today and is projected to grow in the future; this also is the largest the group of students thatdoes not finish their studies in spite of the many services aimed at supporting students' academic success.This study critically investigated the...
Show moreThis study explores the lived experiences of older students who work and have family responsibilities while attending an undergraduate program full-time. Research indicates that this segment of the student population is the only one that is growing today and is projected to grow in the future; this also is the largest the group of students thatdoes not finish their studies in spite of the many services aimed at supporting students' academic success.This study critically investigated the category of the nontraditional student and reviewed the literature about students' college experiences, including the limitations of its theoretical assumptions to describe and explain the nature of the college journey of olderstudents with substantive life experiences. From the notion that learning is lifelong and holistic (Jarvis, 2006), this study combined a student-centered approach with a hermeneutic phenomenological methodology to respond to the following research questions: What is the lifeworld of undergraduate nontraditional students with significantlife experience as they encounter college life? What resources sustain the college experience of undergraduate nontraditional students of and allow navigating the space of college life? What are the changes undergraduate nontraditional students live, the meaning they construct while encountering, and navigating college life?Themes that resulted from the analysis included the participants' experiences as essentially different from that of traditional students. These nontraditional college students bring skills and knowledge that they deploy on behalf of their specific academic goals. The pace of their lives is fundamentally different from the traditional universitystudent's sense of time; they are self-sufficient, making decisions and navigate obstacles.Their new identity as students is re-negotiated with the identities they live outside of campus and they establish ad hoc relationships with members of the universitycommunity.
Show less - Date Issued
- 2018
- Identifier
- CFE0007201, ucf:52255
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007201
- Title
- Experimental confirmation of ballistic nanofriction and quasiparticle interference in Dirac materials.
- Creator
-
Lodge, Michael, Ishigami, Masahiro, Kaden, William, Schelling, Patrick, Del Barco, Enrique, Roy, Tania, University of Central Florida
- Abstract / Description
-
This dissertation is broadly divided into two parts. The first part details the development and usage of an experimental apparatus to measure the dry nanofriction for a well-defined interface at high sliding speeds. I leverage the sensitivity of a quartz crystal microbalance (QCM) to determine the drag coefficient of an ensemble of gold nanocrystals sliding on graphene at speeds up to 11 cm/s. I discuss the theories of velocity-dependent friction, especially at high sliding speeds, and QCM...
Show moreThis dissertation is broadly divided into two parts. The first part details the development and usage of an experimental apparatus to measure the dry nanofriction for a well-defined interface at high sliding speeds. I leverage the sensitivity of a quartz crystal microbalance (QCM) to determine the drag coefficient of an ensemble of gold nanocrystals sliding on graphene at speeds up to 11 cm/s. I discuss the theories of velocity-dependent friction, especially at high sliding speeds, and QCM modeling. I also discuss our synthesis protocols for graphene and molybdenum disulfide, as well as our protocol for fabricating a clean, graphene-laminated QCM device and nanocrystal ensemble. The design and fabrication of our QCM oscillator circuit is presented in detail. The quantitatively-measured the drag coefficient is compared against molecular dynamics simulations at both low and high sliding speeds. We show evidence of a predicted ultra-low friction regime and find that the interaction energy between gold nanocrystals and graphene is lower than previously assumed. In the second part of this dissertation, I detail the band structure measurement of a novel semimetal using scanning tunneling microscopy. In particular, I measured the energy-dependenceof quasiparticle interference patterns at the surface of zirconium silicon sulfide (ZrSiS), a topological nodal line semimetal whose charge carrier quasiparticles possess a pseudospin degree offreedom. The aims of this study were to (1) discover the shape of the band structure above the Fermi level along a high-symmetry direction, (2) discover the energetic location of the line node inthe same high-symmetry direction, and (3) discover the selection rules for k transitions. This study confirms the predicted linearity in E(k) of the band structure above the Fermi level. Additionally,we observe an energy-dependent mechanism for pseudospin scattering. This study also provides the first experimentally-derived estimation of the line node position in E(k).
Show less - Date Issued
- 2018
- Identifier
- CFE0007218, ucf:52222
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007218
- Title
- Analysis of Behaviors in Crowd Videos.
- Creator
-
Mehran, Ramin, Shah, Mubarak, Sukthankar, Gita, Behal, Aman, Tappen, Marshall, Moore, Brian, University of Central Florida
- Abstract / Description
-
In this dissertation, we address the problem of discovery and representation of group activity of humans and objects in a variety of scenarios, commonly encountered in vision applications. The overarching goal is to devise a discriminative representation of human motion in social settings, which captures a wide variety of human activities observable in video sequences. Such motion emerges from the collective behavior of individuals and their interactions and is a significant source of...
Show moreIn this dissertation, we address the problem of discovery and representation of group activity of humans and objects in a variety of scenarios, commonly encountered in vision applications. The overarching goal is to devise a discriminative representation of human motion in social settings, which captures a wide variety of human activities observable in video sequences. Such motion emerges from the collective behavior of individuals and their interactions and is a significant source of information typically employed for applications such as event detection, behavior recognition, and activity recognition. We present new representations of human group motion for static cameras, and propose algorithms for their application to variety of problems.We first propose a method to model and learn the scene activity of a crowd using Social Force Model for the first time in the computer vision community. We present a method to densely estimate the interaction forces between people in a crowd, observed by a static camera. Latent Dirichlet Allocation (LDA) is used to learn the model of the normal activities over extended periods of time. Randomly selected spatio-temporal volumes of interaction forces are used to learn the model of normal behavior of the scene. The model encodes the latent topics of social interaction forces in the scene for normal behaviors. We classify a short video sequence of $n$ frames as normal or abnormal by using the learnt model. Once a sequence of frames is classified as an abnormal, the regions of anomalies in the abnormal frames are localized using the magnitude of interaction forces.The representation and estimation framework proposed above, however, has a few limitations. This algorithm proposes to use a global estimation of the interaction forces within the crowd. It, therefore, is incapable of identifying different groups of objects based on motion or behavior in the scene. Although the algorithm is capable of learning the normal behavior and detects the abnormality, but it is incapable of capturing the dynamics of different behaviors.To overcome these limitations, we then propose a method based on the Lagrangian framework for fluid dynamics, by introducing a streakline representation of flow. Streaklines are traced in a fluid flow by injecting color material, such as smoke or dye, which is transported with the flow and used for visualization. In the context of computer vision, streaklines may be used in a similar way to transport information about a scene, and they are obtained by repeatedly initializing a fixed grid of particles at each frame, then moving both current and past particles using optical flow. Streaklines are the locus of points that connect particles which originated from the same initial position.This approach is advantageous over the previous representations in two aspects: first, its rich representation captures the dynamics of the crowd and changes in space and time in the scene where the optical flow representation is not enough, and second, this model is capable of discovering groups of similar behavior within a crowd scene by performing motion segmentation. We propose a method to distinguish different group behaviors such as divergent/convergent motion and lanes using this framework. Finally, we introduce flow potentials as a discriminative feature to recognize crowd behaviors in a scene. Results of extensive experiments are presented for multiple real life crowd sequences involving pedestrian and vehicular traffic.The proposed method exploits optical flow as the low level feature and performs integration and clustering to obtain coherent group motion patterns. However, we observe that in crowd video sequences, as well as a variety of other vision applications, the co-occurrence and inter-relation of motion patterns are the main characteristics of group behaviors. In other words, the group behavior of objects is a mixture of individual actions or behaviors in specific geometrical layout and temporal order.We, therefore, propose a new representation for group behaviors of humans using the inter-relation of motion patterns in a scene. The representation is based on bag of visual phrases of spatio-temporal visual words. We present a method to match the high-order spatial layout of visual words that preserve the geometry of the visual words under similarity transformations. To perform the experiments we collected a dataset of group choreography performances from the YouTube website. The dataset currently contains four categories of group dances.
Show less - Date Issued
- 2011
- Identifier
- CFE0004482, ucf:49317
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004482
- Title
- Faculty Perspectives and Participation in Implementing an Early Alert System and Intervention in a Community College.
- Creator
-
Bentham, Claudine, King, Kathy (Kathleen), Cox, Dr. Thomas, Hopp, Carolyn, Bosley, Michael, University of Central Florida
- Abstract / Description
-
Early alert systems have been recognized as a high impact practice designed to improve student engagement and student success. Early alert is designed to identify students with at-risk behaviors early in the semester before they decide to drop-out, withdraw, or fail their classes, using resources such as a predictive analysis tool or advising. For an early alert to be successful and efficient, faculty should be included in the process of early alert. This qualitative study examined faculty's...
Show moreEarly alert systems have been recognized as a high impact practice designed to improve student engagement and student success. Early alert is designed to identify students with at-risk behaviors early in the semester before they decide to drop-out, withdraw, or fail their classes, using resources such as a predictive analysis tool or advising. For an early alert to be successful and efficient, faculty should be included in the process of early alert. This qualitative study examined faculty's perspective and experiences when implementing early alert strategies and intervention in a two-year institution. Using Cranton's seven facets of transformative learning as a conceptual framework, this study examined the changes, perception, and experiences of faculty as a result of implementation. The literature reviews best practices that can be considered when faculty designs their early alert strategies and intervention. Participants shared their During and After Implementation Journal experience by completing reflection journals. After careful analysis of their journals and initial interview, the following major themes emerged: a) at-risk behaviors, b) high-impact practices, c) intentionality, d) personal connection, e) perspective transformation, and f) value. As a result of these themes, recommendations were provided to assist faculty development and change agents in two-year institutions in improving early alert methods to increase student success.
Show less - Date Issued
- 2017
- Identifier
- CFE0006857, ucf:51742
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006857
- Title
- Chlamydia trachomatis Transformants Show a Significant Reduction in Rates of Invasion upon Removal of Key Tarp Domains.
- Creator
-
Parrett, Christopher, Jewett, Travis, Roy, Herve, Moore, Sean, University of Central Florida
- Abstract / Description
-
Chlamydia trachomatis is an obligate, intracellular bacterium which is known to cause multiple human infections including nongonococcal urethritis (serovars D-K), lymphogranuloma venereum (serovars L1, L2, L3) and trachoma (serovars A-C). The infectious form of the bacterium, called the elementary body (EB), harbors a type III secreted effector known as Tarp (translocated actin recruiting phosphoprotein) which is a candidate virulence factor and is hypothesized to play a role in C....
Show moreChlamydia trachomatis is an obligate, intracellular bacterium which is known to cause multiple human infections including nongonococcal urethritis (serovars D-K), lymphogranuloma venereum (serovars L1, L2, L3) and trachoma (serovars A-C). The infectious form of the bacterium, called the elementary body (EB), harbors a type III secreted effector known as Tarp (translocated actin recruiting phosphoprotein) which is a candidate virulence factor and is hypothesized to play a role in C. trachomatis' ability to invade and grow within epithelial cells in a human host. C. trachomatis L2 Tarp harbors five unique protein domains which include the Phosphorylation Domain, the Proline Rich Domain, the Actin Binding Domain, and two F-Actin Binding Domains. Tarp has been biochemically characterized in vitro, but it has yet to be characterized in vivo due to a lack of genetic tools in C. trachomatis. Through the recent generation of a chlamydial transformation system, we have created transformants which express epitope tagged wild type or mutant Tarp effectors. In this thesis, C. trachomatis transformants expressing Tarp lacking one of the five biochemically defined protein domains were used to examine both bacterial invasion and bacterial development within mammalian host cells. Our results demonstrate that those EBs which harbor mutant Tarp missing either its Phosphorylation Domain or its Actin Binding Domain were less capable of host cell invasion. However, these transformants, once internalized, were capable of normal development when compared to wild type C. trachomatis or C. trachomatis harboring an epitope tagged wild type Tarp effector. These results suggest that transformant expressed Tarp lacking the Phosphorylation Domain or Actin Binding Domain may be acting as a dominant-negative effector protein. Ultimately, these results support the hypothesis that Tarp is a virulence factor for Chlamydia trachomatis. Furthermore, this data indicates that through the manipulation of the Tarp effector, C. trachomatis pathogenesis may be attenuated.
Show less - Date Issued
- 2016
- Identifier
- CFE0006159, ucf:51142
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006159
- Title
- Adaptive Architectural Strategies for Resilient Energy-Aware Computing.
- Creator
-
Ashraf, Rizwan, DeMara, Ronald, Lin, Mingjie, Wang, Jun, Jha, Sumit, Johnson, Mark, University of Central Florida
- Abstract / Description
-
Reconfigurable logic or Field-Programmable Gate Array (FPGA) devices have the ability to dynamically adapt the computational circuit based on user-specified or operating-condition requirements. Such hardware platforms are utilized in this dissertation to develop adaptive techniques for achieving reliable and sustainable operation while autonomously meeting these requirements. In particular, the properties of resource uniformity and in-field reconfiguration via on-chip processors are exploited...
Show moreReconfigurable logic or Field-Programmable Gate Array (FPGA) devices have the ability to dynamically adapt the computational circuit based on user-specified or operating-condition requirements. Such hardware platforms are utilized in this dissertation to develop adaptive techniques for achieving reliable and sustainable operation while autonomously meeting these requirements. In particular, the properties of resource uniformity and in-field reconfiguration via on-chip processors are exploited to implement Evolvable Hardware (EHW). EHW utilize genetic algorithms to realize logic circuits at runtime, as directed by the objective function. However, the size of problems solved using EHW as compared with traditional approaches has been limited to relatively compact circuits. This is due to the increase in complexity of the genetic algorithm with increase in circuit size. To address this research challenge of scalability, the Netlist-Driven Evolutionary Refurbishment (NDER) technique was designed and implemented herein to enable on-the-fly permanent fault mitigation in FPGA circuits. NDER has been shown to achieve refurbishment of relatively large sized benchmark circuits as compared to related works. Additionally, Design Diversity (DD) techniques which are used to aid such evolutionary refurbishment techniques are also proposed and the efficacy of various DD techniques is quantified and evaluated.Similarly, there exists a growing need for adaptable logic datapaths in custom-designed nanometer-scale ICs, for ensuring operational reliability in the presence of Process, Voltage, and Temperature (PVT) and, transistor-aging variations owing to decreased feature sizes for electronic devices. Without such adaptability, excessive design guardbands are required to maintain the desired integration and performance levels. To address these challenges, the circuit-level technique of Self-Recovery Enabled Logic (SREL) was designed herein. At design-time, vulnerable portions of the circuit identified using conventional Electronic Design Automation tools are replicated to provide post-fabrication adaptability via intelligent techniques. In-situ timing sensors are utilized in a feedback loop to activate suitable datapaths based on current conditions that optimize performance and energy consumption. Primarily, SREL is able to mitigate the timing degradations caused due to transistor aging effects in sub-micron devices by reducing the stress induced on active elements by utilizing power-gating. As a result, fewer guardbands need to be included to achieve comparable performance levels which leads to considerable energy savings over the operational lifetime.The need for energy-efficient operation in current computing systems has given rise to Near-Threshold Computing as opposed to the conventional approach of operating devices at nominal voltage. In particular, the goal of exascale computing initiative in High Performance Computing (HPC) is to achieve 1 EFLOPS under the power budget of 20MW. However, it comes at the cost of increased reliability concerns, such as the increase in performance variations and soft errors. This has given rise to increased resiliency requirements for HPC applications in terms of ensuring functionality within given error thresholds while operating at lower voltages. My dissertation research devised techniques and tools to quantify the effects of radiation-induced transient faults in distributed applications on large-scale systems. A combination of compiler-level code transformation and instrumentation are employed for runtime monitoring to assess the speed and depth of application state corruption as a result of fault injection. Finally, fault propagation models are derived for each HPC application that can be used to estimate the number of corrupted memory locations at runtime. Additionally, the tradeoffs between performance and vulnerability and the causal relations between compiler optimization and application vulnerability are investigated.
Show less - Date Issued
- 2015
- Identifier
- CFE0006206, ucf:52889
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006206
