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- Title
- Rock-a-Buy Baby: Consumerism by New, First-Time Mothers.
- Creator
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Afflerback, Sara, Grauerholz, Elizabeth, Carter, Shannon, Koontz, Amanda, University of Central Florida
- Abstract / Description
-
Rock-a-Buy Baby: Consumerism by New, First-Time Mothers, is the first known sociological exploration of need-based consumption for babies, despite the baby gear industry being a $6-billion-dollar business (whattoexpect.com). Data stemmed from qualitative, semi-structured interviews with new, first-time mothers (3 months (-) 1 year postpartum) conducted within participants' households. The insights gained from the present study tell us a great deal about the (")needs(") that predominantly...
Show moreRock-a-Buy Baby: Consumerism by New, First-Time Mothers, is the first known sociological exploration of need-based consumption for babies, despite the baby gear industry being a $6-billion-dollar business (whattoexpect.com). Data stemmed from qualitative, semi-structured interviews with new, first-time mothers (3 months (-) 1 year postpartum) conducted within participants' households. The insights gained from the present study tell us a great deal about the (")needs(") that predominantly white, middle-class mothers socially constructed in anticipation of their first child, and the consumptive behaviors used to accomplish these "needs." Respondents had turned to similar resources (other mothers, online forums, consumer reports, books, magazines, etc.) to help them construct (")need(") and formulate decisions among commodities. Provided they were relying on comparable, if not overlapping, bodies of knowledge, mothers' narratives about consumer (")need(") were often congruent. Additionally, the ways expectant mothers accumulated items are ritualized and made tradition. The baby shower and gift registration process (which all of my respondents participated in to some variation) are social constructions; these practices, which are so strongly tied to consumption, also constituted reality for mothers, and inevitably, their babies.
Show less - Date Issued
- 2012
- Identifier
- CFE0004258, ucf:49502
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004258
- Title
- Electromagnetic Environment in Payload Fairing Cavities.
- Creator
-
Trout, Dawn, Wahid, Parveen, Wu, Xinzhang, Gong, Xun, Tang, Philip, University of Central Florida
- Abstract / Description
-
An accurate determination of a spacecraft's radio frequency electromagnetic field environment during launch and flight is critical for mission success. Typical fairing structures consist of a parabolic nose and a cylindrical core with diameters of 1 to 5 meters resulting in electrically large dimensions for typical operational sources at S, C and X band where the free space wavelength varies from 0.15 m to 0.03 m. These electrically large size and complex structures at present have internal...
Show moreAn accurate determination of a spacecraft's radio frequency electromagnetic field environment during launch and flight is critical for mission success. Typical fairing structures consist of a parabolic nose and a cylindrical core with diameters of 1 to 5 meters resulting in electrically large dimensions for typical operational sources at S, C and X band where the free space wavelength varies from 0.15 m to 0.03 m. These electrically large size and complex structures at present have internal fairing electromagnetic field evaluation that is limited to general approximation methods and some test data. Though many of today's computational electromagnetic tools can model increasingly complex and large structures, they still have many limitations when used for field determination in electrically large cavities. In this dissertation, a series of test anchored, full wave computational electromagnetic models along with a novel application of the equivalent material property technique are presented to address the electrical, geometrical, and boundary constraints for electromagnetic field determination in composite fairing cavity structures and fairings with acoustic blanketing layers. Both external and internal excitations for these fairing configurations are examined for continuous wave and transient sources. A novel modification of the Nicholson Ross Weir technique is successfully applied to both blanketed aluminum and composite fairing structures and a significant improvement in computational efficiency over the multilayered model approach is obtained. The advantages and disadvantages of using commercially available tools by incorporating Multilevel Fast Multipole Method (MLFMM) and higher order method of moments (HO MoM) to extend their application of MoM to electrically large objects is examined for each continuous wave transmission case. The results obtained with these models are compared with those obtained using approximation techniques based on the Q factor, commonly utilized in the industry, and a significant improvement is seen in a prediction of the fields in these large cavity structures. A statistical distribution of data points within the fairing cavity is examined to study the nature of the fairing cavity field distribution and the effect of the presence of a spacecraft load on these fields is also discussed. In addition, a model with external application of Green's function is examined to address the shielding effectiveness of honeycomb panels in a fairing cavity. Accurate data for lightning induced effects within a fairing structure is not available and hence in this dissertation, a transmission line matrix method model is used to examine induced lightning effects inside a graphite composite fairing structure. The simulated results are compared with test data and show good agreement.
Show less - Date Issued
- 2012
- Identifier
- CFE0004275, ucf:49505
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004275
- Title
- Properties of High Energy Laser Light Transmission through Large Core Optical Cables.
- Creator
-
Kennedy, Christopher, Schulzgen, Axel, Bass, Michael, Soileau, Marion, Gordon, Ali, University of Central Florida
- Abstract / Description
-
Laser induced damage is of interest in studying the transmission of large amounts of optical energy through step-index, large core multimode fibers. Optical fibers often have to be routed around objects when laser light is being transmitted between two locations which require the fiber to bend into a curve. Depending on how tight the bend is, this can result in transmission losses or even catastrophic damage when the energy density of the laser pulse exceeds the damage threshold of silica...
Show moreLaser induced damage is of interest in studying the transmission of large amounts of optical energy through step-index, large core multimode fibers. Optical fibers often have to be routed around objects when laser light is being transmitted between two locations which require the fiber to bend into a curve. Depending on how tight the bend is, this can result in transmission losses or even catastrophic damage when the energy density of the laser pulse exceeds the damage threshold of silica glass. Waveguide theory predicts that light traveling through a bend will form whispering-gallery modes that propagate through total internal reflection bounces along the inside of the outer edge of the bend. This is critical since in these locations the energy density of the light will increase significantly, raising the potential of laser damage, nonlinear effects, and transmission losses. This loss is especially problematic when two 90(&)deg; bends going in opposite directions are in close proximity to each other, forming an 'S-bend'. Light that is grouped along the outer edge going through the first bend will enter the second bend at a sharper angle which causes much high transmission losses and raises the possibility of failure.Models using R-Soft BeamProp and Zemax were developed to study transmission losses, investigate light interactions at critical areas, and predict under which conditions laser damage would occur. BeamProp presents a clearer view of the modal distribution of light within the core of the fiber and is used to analyze how a plane wave with a Gaussian intensity distribution excites the fiber modes. Zemax provides a tool to perform non-sequential ray tracing through the fiber cable and stray light analysis within the core and once the light exits the fiber. Intensity distributions of the cross sectional area of the fiber shows the whispering gallery modes forming as the light propagates around bends and disburses as it propagates afterwards. It was discovered using R-Soft that if the separation distance between bends in an S-bend is approximately 3 mm there exists a condition where maximum transmission occurs. For 365 (&)#181;m diameter core fiber it was calculated that the difference in output power could be as high as 150%. This was initially completely unexpected; however ray tracing using Zemax was able to verify that this distance allows the light to transition so that it enters the 2nd bend at the optimal angle to enter the whispering gallery mode. Experiments were performed that validated the models' predictions and images were captured clearly showing the spatial distribution shift of the light within the core of the fiber.Experiments were performed to verify light grouping together to form whispering gallery modes as predicted by Zemax. Microscope images were taken as a function of distance from various bends to observe the periodic nature in which the laser light fills up the fiber. Additionally, a configuration was setup to examine stimulated Brillioun scattering and determine the onset of laser damage in the fiber. Fibers were tested as a function of bend radius and number of shots and recommendations for future systems were made. Lastly, mechanical failure tests were performed to determine the relationship between stress placed on the fiber through bending and fiber lifetime in a static environment. This allowed a minimum safe bend radius to be calculated for a 30 year lifetime that agreed with previous calculated values.
Show less - Date Issued
- 2013
- Identifier
- CFE0004871, ucf:49668
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004871
- Title
- EXPLORING THE RELATIONSHIP BETWEEN MARITAL EXPECTATIONS AND MARITAL SATISFACTION BETWEEN MARRIED AFRICAN IMMIGRANT COUPLES AND UNITED STATES BORN MARRIED COUPLES.
- Creator
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Ngazimbi, Evadne, Daire, Andrew, University of Central Florida
- Abstract / Description
-
ABSTRACT Marriage is still considered a universal institution in many countries worldwide. Marriage provides benefits for wives, husbands, children, families, and communities. Why Marriage Matters (Wilcox et al., 2005), outlined the benefits of marriage, including improved physical and mental health, biological and social benefits for husbands, wives, children and families in America. In sub-Saharan Africa benefits emanating from marriage included increased survival rates for young children ...
Show moreABSTRACT Marriage is still considered a universal institution in many countries worldwide. Marriage provides benefits for wives, husbands, children, families, and communities. Why Marriage Matters (Wilcox et al., 2005), outlined the benefits of marriage, including improved physical and mental health, biological and social benefits for husbands, wives, children and families in America. In sub-Saharan Africa benefits emanating from marriage included increased survival rates for young children (Omariba & Boyle, 2007); reduced maternal morbidity and mortality rates for women due to reduced risks from self-inflicted abortions (Garenne, Tollman, Kahn, Collins, & Ngwenya, 2001); and improved economic management in homes due to exchanging gender-specific tasks within households (Gezon, 2002). Despite these benefits, approximately half the marriages in the United States end in divorce (Raley & Bumpass, 2003; Smith, 2007). Reduced marital satisfaction leads to dissolution of marriages in the U. S. Marital expectations were associated with marital satisfaction (Juvva & Bhatti, 2006). The purpose of this study was to investigate the relationship between marital expectations and marital satisfaction between African immigrant and United States born married couples. The independent variable was marital expectations, measured with the Marital Expectations Questionnaire (MEQ, Ngazimbi & Daire, 2008). The dependent variables were marital satisfaction, measured by the Relationship Assessment Scale (RAS, Hendrick, 1988), and the Relationship Pleasure Scale (RPS, PAIRS Foundation, 1993). The participants were recruited from nine sites in six states located in three geographical regions. The regions were the Midwest, the West and the Pacific Northwest. They were recruited through faith-based leaders. Participants consisted of 87 couples and 35 individuals who participated without their spouses. This was a mixed methods design. In the quantitative section, three instruments were used to collect data: the MEQ, the RAS, and the RPS. The first section of the MEQ contained four open-ended questions which were used to collect qualitative data. Significant differences were found in the relationships between marital expectations and marital satisfaction between African immigrants and non-immigrants. Qualitative differences and similarities were found between African immigrant and U. S. born married couples. Implications of the findings are discussed for research, counselor education and clinical practice.
Show less - Date Issued
- 2009
- Identifier
- CFE0002629, ucf:48224
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002629
- Title
- Nano-pipette as nanoparticle analyzer and capillary gated ion transistor.
- Creator
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Rudzevich, Yauheni, Chow, Lee, Heinrich, Helge, Schulte, Alfons, Yuan, Jiann-Shiun, University of Central Florida
- Abstract / Description
-
The ability to precisely count inorganic and organic nanoparticles and to measure their size distribution plays a major role in various applications such as drug delivery, nanoparticles counting, and many others. In this work I present a simple resistive pulse method that allows translocations, counting, and measuring the size and velocity distribution of silica nanoparticles and liposomes with diameters from 50 nm to 250 nm. This technique is based on the Coulter counter technique, but has...
Show moreThe ability to precisely count inorganic and organic nanoparticles and to measure their size distribution plays a major role in various applications such as drug delivery, nanoparticles counting, and many others. In this work I present a simple resistive pulse method that allows translocations, counting, and measuring the size and velocity distribution of silica nanoparticles and liposomes with diameters from 50 nm to 250 nm. This technique is based on the Coulter counter technique, but has nanometer size pores. It was found that ionic current drops when nanoparticles enter the nanopore of a pulled micropipette, producing a clear translocation signal. Pulled borosilicate micropipettes with opening 50 ~ 350 nm were used as the detecting instrument. This method provides a direct, fast and cost-effective way to characterize inorganic and organic nanoparticles in a solution. In this work I also introduce a newly developed Capillary Ionic Transistor (CIT). It is presented as a nanodevice which provides control of ionic transport through nanochannel by gate voltage. CIT is Ionic transistor, which employs pulled capillary as nanochannel with a tip diameter smaller than 100 mm. We observed that the gate voltage applied to gate electrode, deposited on the outer wall of a capillary, affect a conductance of nanochannel, due to change of surface charge at the solution/capillary interface. Negative gate voltage corresponds to lower conductivity and positive gate increases conductance of the channel. This effect strongly depends on the size of the channel. In general, at least one dimension of the channel has to be small enough for electrical double layer to overlap.
Show less - Date Issued
- 2014
- Identifier
- CFE0005880, ucf:50882
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005880
- Title
- Batch and Online Implicit Weighted Gaussian Processes for Robust Novelty Detection.
- Creator
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Ramirez Padron, Ruben, Gonzalez, Avelino, Georgiopoulos, Michael, Stanley, Kenneth, Mederos, Boris, Wang, Chung-Ching, University of Central Florida
- Abstract / Description
-
This dissertation aims mainly at obtaining robust variants of Gaussian processes (GPs) that do not require using non-Gaussian likelihoods to compensate for outliers in the training data. Bayesian kernel methods, and in particular GPs, have been used to solve a variety of machine learning problems, equating or exceeding the performance of other successful techniques. That is the case of a recently proposed approach to GP-based novelty detection that uses standard GPs (i.e. GPs employing...
Show moreThis dissertation aims mainly at obtaining robust variants of Gaussian processes (GPs) that do not require using non-Gaussian likelihoods to compensate for outliers in the training data. Bayesian kernel methods, and in particular GPs, have been used to solve a variety of machine learning problems, equating or exceeding the performance of other successful techniques. That is the case of a recently proposed approach to GP-based novelty detection that uses standard GPs (i.e. GPs employing Gaussian likelihoods). However, standard GPs are sensitive to outliers in training data, and this limitation carries over to GP-based novelty detection. This limitation has been typically addressed by using robust non-Gaussian likelihoods. However, non-Gaussian likelihoods lead to analytically intractable inferences, which require using approximation techniques that are typically complex and computationally expensive. Inspired by the use of weights in quasi-robust statistics, this work introduces a particular type of weight functions, called here data weighers, in order to obtain robust GPs that do not require approximation techniques and retain the simplicity of standard GPs. This work proposes implicit weighted variants of batch GP, online GP, and sparse online GP (SOGP) that employ weighted Gaussian likelihoods. Mathematical expressions for calculating the posterior implicit weighted GPs are derived in this work. In our experiments, novelty detection based on our weighted batch GPs consistently and significantly outperformed standard batch GP-based novelty detection whenever data was contaminated with outliers. Additionally, our experiments show that novelty detection based on online GPs can perform similarly to batch GP-based novelty detection. Membership scores previously introduced by other authors are also compared in our experiments.
Show less - Date Issued
- 2015
- Identifier
- CFE0005869, ucf:50858
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005869
- Title
- Building a Foundation for Goal-Attainment and Problem-Solving in Interdisciplinary Studies: Reimagining Web-Based Core Curriculum through a Classical Lens.
- Creator
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Jardaneh, Said, Fiore, Stephen, Sims, Valerie, McDaniel, Rudy, University of Central Florida
- Abstract / Description
-
The core curriculum of interdisciplinary studies undergraduate programs represents interdisciplinarity as a consciously applied process, whether individually or collaboratively, of drawing and integrating insights from various disciplinary perspectives toward complex problem-solving and innovation. At the front-end of these programs students are often introduced to interdisciplinarity through terminology, metaphors, concepts, and context that are intended to familiarize them with the process....
Show moreThe core curriculum of interdisciplinary studies undergraduate programs represents interdisciplinarity as a consciously applied process, whether individually or collaboratively, of drawing and integrating insights from various disciplinary perspectives toward complex problem-solving and innovation. At the front-end of these programs students are often introduced to interdisciplinarity through terminology, metaphors, concepts, and context that are intended to familiarize them with the process. This initiation usually precedes what will ultimately entail a limited number of upper-division courses within the several disciplines or areas that will encompass a unique plan of study characterized by its breadth. The philosophy underlying current pedagogy in interdisciplinary studies appears in many ways to mirror the cognitive habitudes and socio-cultural zeitgeist that have emerged with our increasing connectedness with and reliance on digital technology.This dissertation proposes that through a revised front-end core curriculum revisiting both classical and Ramist pedagogy, and perhaps reframing how we think about interdisciplinarity itself, we need not sacrifice depth for breadth. Rather, we may be able to encourage a broadly applicable self-directed goal-centered mindset in our students that places equal emphasis on both breadth and depth in terms of deliberate knowledge acquisition. Through adapting the initial phases of a cognitivist instructional design model provisional week-by-week, curricular content is presented to illustrate how this endeavor might be realized within the context of interdisciplinary studies or like programs. This core curricular model is intended as an alternative well-suited to both the fully online and mixed mode format as well as the diversity of students within the typical undergraduate interdisciplinary studies program.
Show less - Date Issued
- 2016
- Identifier
- CFE0006120, ucf:51180
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006120
- Title
- Talking Back: Mathematics Teachers Supporting Students' Engagement in a Common Core Standard for Mathematical Practice: A Case Study.
- Creator
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Sotillo Turner, Mercedes, Dixon, Juli, Ortiz, Enrique, Gresham, Gina, Dieker, Lisa, University of Central Florida
- Abstract / Description
-
The researcher in this case study sought to determine the ways in which teachers support their students to create viable arguments and critique the reasoning of others (SMP3). In order to achieve this goal, the self-conceived classroom roles of two teachers, one experienced and one novice, were elicited and then compared to their actualized roles observed in the classroom. Both teachers were provided with professional development focused on supporting student engagement in SMP3. This...
Show moreThe researcher in this case study sought to determine the ways in which teachers support their students to create viable arguments and critique the reasoning of others (SMP3). In order to achieve this goal, the self-conceived classroom roles of two teachers, one experienced and one novice, were elicited and then compared to their actualized roles observed in the classroom. Both teachers were provided with professional development focused on supporting student engagement in SMP3. This professional development was informed by the guidelines that describe the behaviors students should exhibit as they are engaged in the standards for mathematical practice contained in the Common Core State Standards for Mathematics. The teachers were observed, video recorded, and interviewed during and immediately after the professional development. A final observation was performed four weeks after the PD. The marked differences in the teachers' characteristics depicted in each case added to the robustness of the results of the study. A cross-case analysis was performed in order to gauge how the novice and experienced teachers' roles compared and contrasted with each other. The comparison of the teachers' self-perception and their actual roles in the classroom indicated that they were not supporting their students as they thought they were. The analysis yielded specific ways in which novice and experienced teachers might support their students. Furthermore, the cross-case analysis established the support that teachers are able to provide to students depends on (a) teaching experience, (b) teacher content and pedagogical knowledge, (c) questioning, (d) awareness of communication, (e) teacher expectations, and (f) classroom management. Study results provide implications regarding the kinds of support teachers might need given their teaching experience and mathematics content knowledge as they attempt to motivate their students to engage in SMP3.
Show less - Date Issued
- 2014
- Identifier
- CFE0005553, ucf:50275
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005553
- Title
- Climate and landscape controls on seasonal water balance at the watershed scale.
- Creator
-
Chen, Xi, Wang, Dingbao, Chopra, Manoj, Hagen, Scott, Sumner, David, University of Central Florida
- Abstract / Description
-
The main goal of this dissertation is to develop a seasonal water balance model for evaporation, runoff and water storage change based on observations from a large number of watersheds, and further to obtain a comprehensive understanding on the dominant physical controls on intra-annual water balance. Meanwhile, the method for estimating evaporation and water storage based on recession analysis is improved by quantifying the seasonal pattern of the partial contributing area and contributing...
Show moreThe main goal of this dissertation is to develop a seasonal water balance model for evaporation, runoff and water storage change based on observations from a large number of watersheds, and further to obtain a comprehensive understanding on the dominant physical controls on intra-annual water balance. Meanwhile, the method for estimating evaporation and water storage based on recession analysis is improved by quantifying the seasonal pattern of the partial contributing area and contributing storage to base flow during low flow seasons. A new method for quantifying seasonality is developed in this research. The difference between precipitation and soil water storage change, defined as effective precipitation, is considered as the available water. As an analog to climate aridity index, the ratio between monthly potential evaporation and effective precipitation is defined as a monthly aridity index. Water-limited or energy-limited months are defined based on the threshold of 1. Water-limited or energy-limited seasons are defined by aggregating water-limited or energy-limited months, respectively. Seasonal evaporation is modeled by extending the Budyko hypothesis, which is originally for mean annual water balance; while seasonal surface runoff and base flow are modeled by generalizing the proportionality hypothesis originating from the SCS curve number model for surface runoff at the event scale. The developed seasonal evaporation and runoff models are evaluated based on watersheds across the United States. For the extended Budyko model, 250 out of 277 study watersheds have a Nash-Sutcliff efficiency (NSE) higher than 0.5, and for the seasonal runoff model, 179 out of 203 study watersheds have a NSE higher than 0.5. Furthermore, the connection between the seasonal parameters of the developed model and a variety of physical factors in the study watersheds is investigated. For the extended Budyko model, vegetation is identified as an important physical factor that related to the seasonal model parameters. However, the relationship is only strong in water-limited seasons, due to the seasonality of the vegetation coverage. In the seasonal runoff model, the key controlling factors for wetting capacity and initial wetting are soil hydraulic conductivity and maximum rainfall intensity respectively. As for initial evaporation, vegetation is identified as the strongest controlling factor. Besides long-term climate, this research identifies the key controlling factors on seasonal water balance: the effects of soil water storage, vegetation, soil hydraulic conductivity, and storminess. The developed model is applied to the Chipola River watershed and the Apalachicola River basin in Florida for assessing potential climate change impact on the seasonal water balance. The developed model performance is compared with a physically-based distributed hydrologic model of the Soil Water Assessment Tool, showing a good performance for seasonal runoff, evaporation and storage change.
Show less - Date Issued
- 2014
- Identifier
- CFE0005313, ucf:50519
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005313
- Title
- Investigating the relationships between preferences, gender, and high school students' geometry performance.
- Creator
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Mainali, Bhesh, Haciomeroglu, Erhan, Dixon, Juli, Andreasen, Janet, Bai, Haiyan, University of Central Florida
- Abstract / Description
-
In this quantitative study, the relationships between high school students' preference for solution methods, geometry performance, task difficulty, and gender were investigated. The data was collected from 161 high school students from six different schools at a county located in central Florida in the United States. The study was conducted during the 2013(-)2014 school year. The participants represented a wide range in socioeconomic status, were from a range of grades (10-12), and were...
Show moreIn this quantitative study, the relationships between high school students' preference for solution methods, geometry performance, task difficulty, and gender were investigated. The data was collected from 161 high school students from six different schools at a county located in central Florida in the United States. The study was conducted during the 2013(-)2014 school year. The participants represented a wide range in socioeconomic status, were from a range of grades (10-12), and were enrolled in different mathematics courses (Algebra 2, Geometry, Financial Algebra, and Pre-calculus). Data were collected primarily with the aid of a geometry test and a geometry questionnaire. Using a think-aloud protocol, a short interview was also conducted with some students.For the purpose of statistical analysis, students' preferences for solution methods were quantified into numeric values, and then a visuality score was obtained for each student. Students' visuality scores ranged from -12 to +12. The visuality scores were used to assess students' preference for solution methods. A standardized test score was used to measure students' geometry performance. The data analysis indicated that the majority of students were visualizers. The statistical analysis revealed that there was not an association between preference for solution methods and students' geometry performance. The preference for solving geometry problems using either visual or nonvisual methods was not influenced by task difficulty. Students were equally likely to employ visual as well as nonvisual solution methods regardless of the task difficulty. Gender was significant in geometry performance but not in preference for solution methods. Female students' geometry performance was significantly higher than male students' geometry performance. The findings of this study suggested that instruction should be focused on incorporating both visual and nonvisual teaching strategies in mathematics lesson activities in order to develop preference for both visual and nonvisual solution methods.
Show less - Date Issued
- 2014
- Identifier
- CFE0005374, ucf:50448
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005374
- Title
- FINITE ELEMENT METHOD MODELING OF ADVANCED ELECTRONIC DEVICES.
- Creator
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Chen, Yupeng, Wu, Thomas, University of Central Florida
- Abstract / Description
-
In this dissertation, we use finite element method together with other numerical techniques to study advanced electron devices. We study the radiation properties in electron waveguide structure with multi-step discontinuities and soft wall lateral confinement. Radiation mechanism and conditions are examined by numerical simulation of dispersion relations and transport properties. The study of geometry variations shows its significant impact on the radiation intensity and direction. In...
Show moreIn this dissertation, we use finite element method together with other numerical techniques to study advanced electron devices. We study the radiation properties in electron waveguide structure with multi-step discontinuities and soft wall lateral confinement. Radiation mechanism and conditions are examined by numerical simulation of dispersion relations and transport properties. The study of geometry variations shows its significant impact on the radiation intensity and direction. In particular, the periodic corrugation structure exhibits strong directional radiation. This interesting feature may be useful to design a nano-scale transmitter, a communication device for future nano-scale system. Non-quasi-static effects in AC characteristics of carbon nanotube field-effect transistors are examined by solving a full time-dependent, open-boundary Schrödinger equation. The non-quasi-static characteristics, such as the finite channel charging time, and the dependence of small signal transconductance and gate capacitance on the frequency, are explored. The validity of the widely used quasi-static approximation is examined. The results show that the quasi-static approximation overestimates the transconductance and gate capacitance at high frequencies, but gives a more accurate value for the intrinsic cut-off frequency over a wide range of bias conditions. The influence of metal interconnect resistance on the performance of vertical and lateral power MOSFETs is studied. Vertical MOSFETs in a D2PAK and DirectFET package, and lateral MOSFETs in power IC and flip chip are investigated as the case studies. The impact of various layout patterns and material properties on RDS(on) will provide useful guidelines for practical vertical and lateral power MOSFETs design.
Show less - Date Issued
- 2006
- Identifier
- CFE0001389, ucf:46987
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001389
- Title
- DECISION-MAKER TRADE-OFFS IN MULTIPLE RESPONSE SURFACE OPTIMIZATION.
- Creator
-
Hawkins, Alicia, Armacost, Robert, University of Central Florida
- Abstract / Description
-
The focus of this dissertation is on improving decision-maker trade-offs and the development of a new constrained methodology for multiple response surface optimization. There are three key components of the research: development of the necessary conditions and assumptions associated with constrained multiple response surface optimization methodologies; development of a new constrained multiple response surface methodology; and demonstration of the new method. The necessary conditions for and...
Show moreThe focus of this dissertation is on improving decision-maker trade-offs and the development of a new constrained methodology for multiple response surface optimization. There are three key components of the research: development of the necessary conditions and assumptions associated with constrained multiple response surface optimization methodologies; development of a new constrained multiple response surface methodology; and demonstration of the new method. The necessary conditions for and assumptions associated with constrained multiple response surface optimization methods were identified and found to be less restrictive than requirements previously described in the literature. The conditions and assumptions required for a constrained method to find the most preferred non-dominated solution are to generate non-dominated solutions and to generate solutions consistent with decision-maker preferences among the response objectives. Additionally, if a Lagrangian constrained method is used, the preservation of convexity is required in order to be able to generate all non-dominated solutions. The conditions required for constrained methods are significantly fewer than those required for combined methods. Most of the existing constrained methodologies do not incorporate any provision for a decision-maker to explicitly determine the relative importance of the multiple objectives. Research into the larger area of multi-criteria decision-making identified the interactive surrogate worth trade-off algorithm as a potential methodology that would provide that capability in multiple response surface optimization problems. The ISWT algorithm uses an ε-constraint formulation to guarantee a non-dominated solution, and then interacts with the decision-maker after each iteration to determine the preference of the decision-maker in trading-off the value of the primary response for an increase in value of a secondary response. The current research modified the ISWT algorithm to develop a new constrained multiple response surface methodology that explicitly accounts for decision-maker preferences. The new Modified ISWT (MISWT) method maintains the essence of the original method while taking advantage of the specific properties of multiple response surface problems to simplify the application of the method. The MISWT is an accessible computer-based implementation of the ISWT. Five test problems from the multiple response surface optimization literature were used to demonstrate the new methodology. It was shown that this methodology can handle a variety of types and numbers of responses and independent variables. Furthermore, it was demonstrated that the methodology can be successful using a priori information from the decision-maker about bounds or targets or can use the extreme values obtained from the region of operability. In all cases, the methodology explicitly considered decision-maker preferences and provided non-dominated solutions. The contribution of this method is the removal of implicit assumptions and includes the decision-maker in explicit trade-offs among multiple objectives or responses.
Show less - Date Issued
- 2007
- Identifier
- CFE0001765, ucf:47272
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001765
- Title
- INTEGRATING STUDENT-CENTERED LEARNING TO PROMOTE CRITICAL THINKING IN HIGH SCHOOL SOCIAL STUDIES CLASSROOMS.
- Creator
-
Sayre, Elaine, Russell, William, University of Central Florida
- Abstract / Description
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Traditional teacher-centered methods of lectures and PowerPoint presentations are commonly used when teaching secondary social studies, yet these methods continually prove to be boring for most high school students and neglect to teach critical thinking skills. Student-centered methods are different than teacher-centered methods because these methods incorporate several learning styles, cooperative activities, and even technology in order to engage the student and promote critical thinking...
Show moreTraditional teacher-centered methods of lectures and PowerPoint presentations are commonly used when teaching secondary social studies, yet these methods continually prove to be boring for most high school students and neglect to teach critical thinking skills. Student-centered methods are different than teacher-centered methods because these methods incorporate several learning styles, cooperative activities, and even technology in order to engage the student and promote critical thinking skills. Critical thinking is important for students to master because it gives them the skills to move past the obvious and make individual connections with the text. The intent of this thesis was to explore the effectiveness of integrating student-centered methods in high school social studies classrooms as a means of promoting critical thinking skills. All students were given the same pretest and posttests. Students were divided into three groups: one was taught using student-centered methods, one was taught using teacher-centered methods, and one was the control group and was not directly taught by anyone. Based on analyzing students' posttest scores compared to their pre-test scores, student-centered teaching produced a higher average score increase, though all methods had students who scored higher, and students whose scores remained constant. Evidence and student feedback showed that continued future research should be conducted to see if student-centered methods should be used throughout all secondary social studies classrooms to promote critical thinking.
Show less - Date Issued
- 2013
- Identifier
- CFH0004486, ucf:45078
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004486
- Title
- Wireless Power Transfer for Space Applications: System Design and Electromagnetic Compatibility Compliance of Radiated Emissions.
- Creator
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Vazquez Ramos, Gabriel, Yuan, Jiann-Shiun, Sundaram, Kalpathy, Wu, Xinzhang, Soto Toro, Felix, University of Central Florida
- Abstract / Description
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This dissertation evaluates the possibility of wireless power transfer (WPT) systems for space applications, with an emphasis in launch vehicles (rockets). After performing literature review for WPT systems, it was identified that magnetic resonance provides the more suited set of characteristics for this application. Advanced analysis, simulation and testing were performed to magnetic resonance WPT systems to acquire system performance insight. This was accomplished by evaluating/varying...
Show moreThis dissertation evaluates the possibility of wireless power transfer (WPT) systems for space applications, with an emphasis in launch vehicles (rockets). After performing literature review for WPT systems, it was identified that magnetic resonance provides the more suited set of characteristics for this application. Advanced analysis, simulation and testing were performed to magnetic resonance WPT systems to acquire system performance insight. This was accomplished by evaluating/varying coupling configuration, load effects and magnetic element physical characteristics (i.e. wire material, loop radius, etc.). It was identified by analysis, circuit simulation and testing that the best coupling configuration for this application was series-series and series-shunt with Litz wire loop inductors. The main concern identified for the implementation of these systems for space applications was radiated emissions that could potentially generate electromagnetic interference (EMI). To address this EMI concern, we developed the Electromagnetic Compatibility Radiated Emissions Compliance Design Evaluation Approach for WPT Space Systems. This approach systematically allocates key analyses, simulations and tests procedures to predict WPT EMC compliance to NASA's EMC standard Mil-Std-461E/F. Three prototype/magnetic elements were successfully assessed by implementing the WPT EMC design approach. The electric fields intensity generated by the WPT prototypes/magnetic elements tested were: 30.02 dBuV/m, 28.90 dBuV/m and 82.13 dBuV/m (requirement limit: 140 dBuV/m). All three prototypes successfully transferred power wirelessly and successfully met the NASA EMC requirements.
Show less - Date Issued
- 2012
- Identifier
- CFE0004448, ucf:49344
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004448
- Title
- Image degradation due to surface scattering in the presence of aberrations.
- Creator
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Choi, Narak, Harvey, James, Zeldovich, Boris, Moharam, M., Eastes, Richard, University of Central Florida
- Abstract / Description
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This dissertation focuses on the scattering phenomena by well-polished optical mirror surfaces. Specifically, predicting image degradation by surface scatter from rough mirror surfaces for a two-mirror telescope operating at extremely short wavelengths (9nm~30nm) is performed. To evaluate image quality, surface scatter is predicted from the surface metrology data and the point spread function in the presence of both surface scatter and aberrations is calculated.For predicting the scattering...
Show moreThis dissertation focuses on the scattering phenomena by well-polished optical mirror surfaces. Specifically, predicting image degradation by surface scatter from rough mirror surfaces for a two-mirror telescope operating at extremely short wavelengths (9nm~30nm) is performed. To evaluate image quality, surface scatter is predicted from the surface metrology data and the point spread function in the presence of both surface scatter and aberrations is calculated.For predicting the scattering intensity distribution, both numerical and analytic methods are considered. Among the numerous analytic methods, the small perturbation method (classical Rayleigh-Rice surface scatter theory), the Kirchhoff approximation method (classical Beckman-Kirchhoff surface scatter theory), and the generalized Harvey-Shack surface scatter theory are adopted. As a numerical method, the integral equation method (method of moments) known as a rigorous solution is discussed. Since the numerical method is computationally too intensive to obtain the scattering prediction directly for the two mirror telescope, it is used for validating the three analytic approximate methods in special cases. In our numerical comparison work, among the three approximate methods, the generalized Harvey-Shack model shows excellent agreement to the rigorous solution and it is used to predict surface scattering from the mirror surfaces.Regarding image degradation due to surface scatter in the presence of aberrations, it is shown that the composite point spread function is obtained in explicit form in terms of convolutions of the geometrical point spread function and scaled bidirectional scattering distribution functions of the individual surfaces of the imaging system. The approximations and assumptions in this formulation are discussed. The result is compared to the irradiance distribution obtained using commercial non-sequential ray tracing software for the case of a two-mirror telescope operating at the extreme ultra-violet wavelengths and the two results are virtually identical. Finally, the image degradation due to the surface scatter from the mirror surfaces and the aberration of the telescope is evaluated in terms of the fractional ensquared energy (for different wavelengths and field angles) which is commonly used as an image quality requirement on many NASA astronomy programs.
Show less - Date Issued
- 2012
- Identifier
- CFE0004289, ucf:49492
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004289
- Title
- A MODEL INTEGRATED MESHLESS SOLVER (MIMS) FOR FLUID FLOW AND HEAT TRANSFER.
- Creator
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Gerace, Salvadore, Kassab, Alain, University of Central Florida
- Abstract / Description
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Numerical methods for solving partial differential equations are commonplace in the engineering community and their popularity can be attributed to the rapid performance improvement of modern workstations and desktop computers. The ubiquity of computer technology has allowed all areas of engineering to have access to detailed thermal, stress, and fluid flow analysis packages capable of performing complex studies of current and future designs. The rapid pace of computer development, however,...
Show moreNumerical methods for solving partial differential equations are commonplace in the engineering community and their popularity can be attributed to the rapid performance improvement of modern workstations and desktop computers. The ubiquity of computer technology has allowed all areas of engineering to have access to detailed thermal, stress, and fluid flow analysis packages capable of performing complex studies of current and future designs. The rapid pace of computer development, however, has begun to outstrip efforts to reduce analysis overhead. As such, most commercially available software packages are now limited by the human effort required to prepare, develop, and initialize the necessary computational models. Primarily due to the mesh-based analysis methods utilized in these software packages, the dependence on model preparation greatly limits the accessibility of these analysis tools. In response, the so-called meshless or mesh-free methods have seen considerable interest as they promise to greatly reduce the necessary human interaction during model setup. However, despite the success of these methods in areas demanding high degrees of model adaptability (such as crack growth, multi-phase flow, and solid friction), meshless methods have yet to gain notoriety as a viable alternative to more traditional solution approaches in general solution domains. Although this may be due (at least in part) to the relative youth of the techniques, another potential cause is the lack of focus on developing robust methodologies. The failure to approach development from a practical perspective has prevented researchers from obtaining commercially relevant meshless methodologies which reach the full potential of the approach. The primary goal of this research is to present a novel meshless approach called MIMS (Model Integrated Meshless Solver) which establishes the method as a generalized solution technique capable of competing with more traditional PDE methodologies (such as the finite element and finite volume methods). This was accomplished by developing a robust meshless technique as well as a comprehensive model generation procedure. By closely integrating the model generation process into the overall solution methodology, the presented techniques are able to fully exploit the strengths of the meshless approach to achieve levels of automation, stability, and accuracy currently unseen in the area of engineering analysis. Specifically, MIMS implements a blended meshless solution approach which utilizes a variety of shape functions to obtain a stable and accurate iteration process. This solution approach is then integrated with a newly developed, highly adaptive model generation process which employs a quaternary triangular surface discretization for the boundary, a binary-subdivision discretization for the interior, and a unique shadow layer discretization for near-boundary regions. Together, these discretization techniques are able to achieve directionally independent, automatic refinement of the underlying model, allowing the method to generate accurate solutions without need for intermediate human involvement. In addition, by coupling the model generation with the solution process, the presented method is able to address the issue of ill-constructed geometric input (small features, poorly formed faces, etc.) to provide an intuitive, yet powerful approach to solving modern engineering analysis problems.
Show less - Date Issued
- 2010
- Identifier
- CFE0003299, ucf:48489
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003299
- Title
- Spray Deposition Modeling of Carbon Nano-Inks.
- Creator
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Sparkman, John, Gou, Jihua, Xu, Yunjun, Lin, Kuo-Chi, University of Central Florida
- Abstract / Description
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Carbon nanopaper (CNP) exhibits qualities that are desirable for a number of applications such as flame retardancy, lightning protection, and flexible printed circuit boards. CNP has become a desired engineering material in many important sectors of industries such as space, automotive, aviation, and military. However the production of consistent thicknesses and dispersion remains a challenge for practical use. Most of the standard methods of production do not allow for continuous...
Show moreCarbon nanopaper (CNP) exhibits qualities that are desirable for a number of applications such as flame retardancy, lightning protection, and flexible printed circuit boards. CNP has become a desired engineering material in many important sectors of industries such as space, automotive, aviation, and military. However the production of consistent thicknesses and dispersion remains a challenge for practical use. Most of the standard methods of production do not allow for continuous applications or digital fabrication of the CNP. In this work, CNP is produced two different ways that allows for continuous production and digital fabrication. The continuous CNP making technique uses vacuum infiltration along with air atomization and a continuous drive belt system to produce a continuous roll of the CNP. This system is able to produce an 11 (&)#181;m (&)#177; 2 (&)#181;m CNP at 6 inches per min with an electrical resistivity of 59 ? per square. The major advantage of this production process is the ability to mass manufacture the CNP. Spray deposition modeling (SDM) is a digital fabrication process that uses a 12 array bubble jet nozzle attached to a digital control x-y plotter combined with a heated substrate which induces evaporation. This process is able to produce paper with variable thicknesses in defined locations. The maximum thickness of the CNP produced is 10 (&)#181;m with a resistivity of 95.7 ? per square. A strong advantage of this CNP production method comes from the ability to digitally print images. The controllable thickness and selective location printing presents an effective alternative to costlier methods and provides a solution to many geometrical CNP issues.
Show less - Date Issued
- 2015
- Identifier
- CFE0006231, ucf:51073
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006231
- Title
- Weighted Low-Rank Approximation of Matrices:Some Analytical and Numerical Aspects.
- Creator
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Dutta, Aritra, Li, Xin, Sun, Qiyu, Mohapatra, Ram, Nashed, M, Shah, Mubarak, University of Central Florida
- Abstract / Description
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This dissertation addresses some analytical and numerical aspects of a problem of weighted low-rank approximation of matrices. We propose and solve two different versions of weighted low-rank approximation problems. We demonstrate, in addition, how these formulations can be efficiently used to solve some classic problems in computer vision. We also present the superior performance of our algorithms over the existing state-of-the-art unweighted and weighted low-rank approximation algorithms...
Show moreThis dissertation addresses some analytical and numerical aspects of a problem of weighted low-rank approximation of matrices. We propose and solve two different versions of weighted low-rank approximation problems. We demonstrate, in addition, how these formulations can be efficiently used to solve some classic problems in computer vision. We also present the superior performance of our algorithms over the existing state-of-the-art unweighted and weighted low-rank approximation algorithms.Classical principal component analysis (PCA) is constrained to have equal weighting on the elements of the matrix, which might lead to a degraded design in some problems. To address this fundamental flaw in PCA, Golub, Hoffman, and Stewart proposed and solved a problem of constrained low-rank approximation of matrices: For a given matrix $A = (A_1\;A_2)$, find a low rank matrix $X = (A_1\;X_2)$ such that ${\rm rank}(X)$ is less than $r$, a prescribed bound, and $\|A-X\|$ is small.~Motivated by the above formulation, we propose a weighted low-rank approximation problem that generalizes the constrained low-rank approximation problem of Golub, Hoffman and Stewart.~We study a general framework obtained by pointwise multiplication with the weight matrix and consider the following problem:~For a given matrix $A\in\mathbb{R}^{m\times n}$ solve:\begin{eqnarray*}\label{weighted problem}\min_{\substack{X}}\|\left(A-X\right)\odot W\|_F^2~{\rm subject~to~}{\rm rank}(X)\le r,\end{eqnarray*}where $\odot$ denotes the pointwise multiplication and $\|\cdot\|_F$ is the Frobenius norm of matrices.In the first part, we study a special version of the above general weighted low-rank approximation problem.~Instead of using pointwise multiplication with the weight matrix, we use the regular matrix multiplication and replace the rank constraint by its convex surrogate, the nuclear norm, and consider the following problem:\begin{eqnarray*}\label{weighted problem 1}\hat{X} (&)=(&) \arg \min_X \{\frac{1}{2}\|(A-X)W\|_F^2 +\tau\|X\|_\ast\},\end{eqnarray*}where $\|\cdot\|_*$ denotes the nuclear norm of $X$.~Considering its resemblance with the classic singular value thresholding problem we call it the weighted singular value thresholding~(WSVT)~problem.~As expected,~the WSVT problem has no closed form analytical solution in general,~and a numerical procedure is needed to solve it.~We introduce auxiliary variables and apply simple and fast alternating direction method to solve WSVT numerically.~Moreover, we present a convergence analysis of the algorithm and propose a mechanism for estimating the weight from the data.~We demonstrate the performance of WSVT on two computer vision applications:~background estimation from video sequences~and facial shadow removal.~In both cases,~WSVT shows superior performance to all other models traditionally used. In the second part, we study the general framework of the proposed problem.~For the special case of weight, we study the limiting behavior of the solution to our problem,~both analytically and numerically.~In the limiting case of weights,~as $(W_1)_{ij}\to\infty, W_2=\mathbbm{1}$, a matrix of 1,~we show the solutions to our weighted problem converge, and the limit is the solution to the constrained low-rank approximation problem of Golub et. al. Additionally, by asymptotic analysis of the solution to our problem,~we propose a rate of convergence.~By doing this, we make explicit connections between a vast genre of weighted and unweighted low-rank approximation problems.~In addition to these, we devise a novel and efficient numerical algorithm based on the alternating direction method for the special case of weight and present a detailed convergence analysis.~Our approach improves substantially over the existing weighted low-rank approximation algorithms proposed in the literature.~Finally, we explore the use of our algorithm to real-world problems in a variety of domains, such as computer vision and machine learning. Finally, for a special family of weights, we demonstrate an interesting property of the solution to the general weighted low-rank approximation problem. Additionally, we devise two accelerated algorithms by using this property and present their effectiveness compared to the algorithm proposed in Chapter 4.
Show less - Date Issued
- 2016
- Identifier
- CFE0006833, ucf:51789
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006833
- Title
- Field Evaluation of Insync Adaptive Traffic Signal Control System in Multiple Environments Using Multiple Approaches.
- Creator
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Shafik, Md Shafikul Islam, Radwan, Essam, Abou-Senna, Hatem, Eluru, Naveen, University of Central Florida
- Abstract / Description
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Since the beginning of signalization of intersections, the management of traffic congestion is one of most critical challenges specifically for the city and urbanized area. Almost all the municipal agencies struggle to manage the perplexities associated with traffic congestion or signal control. The Adaptive Traffic Control System (ATCS), an advanced and major technological component of the Intelligent Transportation Systems (ITS) is considered the most dynamic and real-time traffic...
Show moreSince the beginning of signalization of intersections, the management of traffic congestion is one of most critical challenges specifically for the city and urbanized area. Almost all the municipal agencies struggle to manage the perplexities associated with traffic congestion or signal control. The Adaptive Traffic Control System (ATCS), an advanced and major technological component of the Intelligent Transportation Systems (ITS) is considered the most dynamic and real-time traffic management technology and has potential to effectively manage rapidly varying traffic flow relative to the current state-of-the-art traffic management practices.InSync ATCS is deployed in multiple states throughout the US and expanding on a large scale. Although there had been several 'Measure of Effectiveness' studies performed previously, the performance of InSync is not unquestionable especially because the previous studies failed to subject for multiple environments, approaches, and variables. Most studies are accomplished through a single approach using simple/na(&)#239;ve before-after method without any control group/parameter. They also lacked ample statistical analysis, historical, maturation and regression artifacts. An attempt to evaluate the InSync ATCS in varying conditions through multiple approaches was undertaken for the SR-434 and Lake Underhill corridor in Orange County, Florida. A before-after study with an adjacent corridor as control group and volume as a control parameter has been performed where data of multiple variables were collected by three distinct procedures. The average/floating-car method was utilized as a rudimentary data collection process and 'BlueMac' and 'InSync' system database was considered as secondary data sources. Data collected for three times a day for weekdays and weekends before and after the InSync ATCS was deployed.Results show variation in both performance and scale. It proved ineffective in some of the cases, especially for the left turns, total intersection queue/delay and when the intersection volumes approach capacity. The results are verified through appropriate statistical analysis.
Show less - Date Issued
- 2017
- Identifier
- CFE0006915, ucf:51687
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006915
- Title
- Examining Multiple Approaches for the Transferability of Safety Performance Functions.
- Creator
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Farid, Ahmed Tarek Ahmed, Abdel-Aty, Mohamed, Lee, JaeYoung, Eluru, Naveen, University of Central Florida
- Abstract / Description
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Safety performance functions (SPFs) are essential in road safety since they are used to predict crash frequencies. They are commonly applied for detecting hot spots in network screening and assessing whether road safety countermeasures are effective. In the Highway Safety Manual (HSM), SPFs are provided for several crash classifications for several types of roadway facilities. The SPFs of the HSM are developed using data from multiple states. In regions where jurisdiction specific SPFs are...
Show moreSafety performance functions (SPFs) are essential in road safety since they are used to predict crash frequencies. They are commonly applied for detecting hot spots in network screening and assessing whether road safety countermeasures are effective. In the Highway Safety Manual (HSM), SPFs are provided for several crash classifications for several types of roadway facilities. The SPFs of the HSM are developed using data from multiple states. In regions where jurisdiction specific SPFs are not available, it is custom to adopt nationwide SPFs for crash predictions then apply a calibration factor. Yet, the research is limited regarding the application of national SPFs for local jurisdictions. In this study, the topic of transferability is explored by examining rural multilane highway SPFs from Florida, Ohio, and California. That is for both divided segments and intersections. Traffic, road geometrics and crash data from the three states are collected to develop one-state, two-state and three-state SPFs. The SPFs are negative binomial models taking the form of those of the HSM. Evaluation of the transferability of models is undertaken by calculating a measure known as the transfer index. It is used to explain which SPFs may be transferred tolerably to other jurisdictions. According to the results, the transferability of rural divided segments' SPFs of Florida to California and vice versa is superior to that of Ohio's SPFs. For four-leg signalized intersections, neither state's models are transferable to any state. Also, the transfer index indicates improved transferability when using pooled data from multiple states. Furthermore, a modified version of the Empirical Bayes method that is responsible for segment specific adjustment factors is proposed as an alternative to the HSM calibration method. It is used to adjust crash frequencies predicted by the SPFs being transferred to the jurisdiction of interest. The modified method, proposed, outperforms the HSM calibration method as per the analysis results.
Show less - Date Issued
- 2015
- Identifier
- CFE0006298, ucf:51604
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006298
