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(1 - 12 of 12)
- Title
- A STUDY OF DIGITAL COMMUNICATION TOOLS USED IN ONLINE HIGH SCHOOL COURSES.
- Creator
-
Putney, Nathan, Gunter, Glenda, University of Central Florida
- Abstract / Description
-
The purpose of this study was to determine the degree to which selected communication tools used by teachers who teach online are positively perceived by their students in improving feelings of self-efficacy and motivation, and which tools may be perceived to be significantly more effective than the others. Students from the Florida Virtual School, a leader in online course delivery for grades 6-12, were surveyed to find their perceptions about how their teachers' use of email, Instant...
Show moreThe purpose of this study was to determine the degree to which selected communication tools used by teachers who teach online are positively perceived by their students in improving feelings of self-efficacy and motivation, and which tools may be perceived to be significantly more effective than the others. Students from the Florida Virtual School, a leader in online course delivery for grades 6-12, were surveyed to find their perceptions about how their teachers' use of email, Instant Messaging, chat, the telephone, discussion area, whiteboard, and assignment feedback affected their motivation and success in an online high school course. Correlations were done to discover if there were any significant relationships between variables that relate to teacher interaction and motivation. In addition, distributions of student responses to survey questions about digital communication tools and demographics were examined. It was found that there is a high degree of correlation between frequency of teachers' use of digital communication tools and student's perception of their level of motivation. It was also found that the digital communication tools most frequently used by teachers in communicating with their students were email, the telephone, and assignment feedback, and that the students found these same tools the most helpful in their learning. In addition, no significant demographic differences were found in students' perception of teacher's use of tools to enhance learning and motivation in their courses except in the number of previous online courses taken. These findings can help direct online high school teachers in their selection of digital tools used to communicate with their students.
Show less - Date Issued
- 2008
- Identifier
- CFE0002333, ucf:47784
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002333
- Title
- DIGITAL SIGNAL PROCESSING TECHNIQUES FOR COHERENT OPTICAL COMMUNICATION.
- Creator
-
Goldfarb, Gilad, Li, Guifang, University of Central Florida
- Abstract / Description
-
Coherent detection with subsequent digital signal processing (DSP) is developed, analyzed theoretically and numerically and experimentally demonstrated in various fiber‐optic transmission scenarios. The use of DSP in conjunction with coherent detection unleashes the benefits of coherent detection which rely on the preservation of full information of the incoming field. These benefits include high receiver sensitivity, the ability to achieve high spectral‐efficiency and the use of...
Show moreCoherent detection with subsequent digital signal processing (DSP) is developed, analyzed theoretically and numerically and experimentally demonstrated in various fiber‐optic transmission scenarios. The use of DSP in conjunction with coherent detection unleashes the benefits of coherent detection which rely on the preservation of full information of the incoming field. These benefits include high receiver sensitivity, the ability to achieve high spectral‐efficiency and the use of advanced modulation formats. With the immense advancements in DSP speeds, many of the problems hindering the use of coherent detection in optical transmission systems have been eliminated. Most notably, DSP alleviates the need for hardware phase‐locking and polarization tracking, which can now be achieved in the digital domain. The complexity previously associated with coherent detection is hence significantly diminished and coherent detection is once again considered a feasible detection alternative. In this thesis, several aspects of coherent detection (with or without subsequent DSP) are addressed. Coherent detection is presented as a means to extend the dispersion limit of a duobinary signal using an analog decision‐directed phase‐lock loop. Analytical bit‐error ratio estimation for quadrature phase‐shift keying signals is derived. To validate the promise for high spectral efficiency, the orthogonal‐wavelength‐division multiplexing scheme is suggested. In this scheme the WDM channels are spaced at the symbol rate, thus achieving the spectral efficiency limit. Theory, simulation and experimental results demonstrate the feasibility of this approach. Infinite impulse response filtering is shown to be an efficient alternative to finite impulse response filtering for chromatic dispersion compensation. Theory, design considerations, simulation and experimental results relating to this topic are presented. Interaction between fiber dispersion and nonlinearity remains the last major challenge deterministic effects pose for long‐haul optical data transmission. Experimental results which demonstrate the possibility to digitally mitigate both dispersion and nonlinearity are presented. Impairment compensation is achieved using backward propagation by implementing the split‐step method. Efficient realizations of the dispersion compensation operator used in this implementation are considered. Infinite‐impulse response and wavelet‐based filtering are both investigated as a means to reduce the required computational load associated with signal backward‐propagation. Possible future research directions conclude this dissertation.
Show less - Date Issued
- 2008
- Identifier
- CFE0002384, ucf:47763
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002384
- Title
- Computationally Efficient Digital Backward Propagation for Fiber Nonlinearity Compensation.
- Creator
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Zhu, Likai, Li, Guifang, Schulzgen, Axel, Likamwa, Patrick, Wei, Lei, University of Central Florida
- Abstract / Description
-
The next generation fiber transmission system is limited by fiber nonlinearity. A distributed nonlinearity compensation method, known as Digital Backward Propagation (DBP), is necessary for effective compensation of the joint effect of dispersion and nonlinearity. However, in order for DBP to be accurate, a large number of steps are usually required for long-haul transmission, resulting in a heavy computational load.In real time DBP implementation, the FIR filters can be used for dispersion...
Show moreThe next generation fiber transmission system is limited by fiber nonlinearity. A distributed nonlinearity compensation method, known as Digital Backward Propagation (DBP), is necessary for effective compensation of the joint effect of dispersion and nonlinearity. However, in order for DBP to be accurate, a large number of steps are usually required for long-haul transmission, resulting in a heavy computational load.In real time DBP implementation, the FIR filters can be used for dispersion compensation and account for most of the computation per step. A method of designing a complementary filter pair is proposed. The individual errors in the frequency response of the two filters in a complementary filter pair cancel each other. As a result, larger individual filter error can be tolerated and the required filter length is significantly reduced.Unequal step size can be used in DBP to minimize the number of steps. For unrepeatered transmission with distributed Raman amplification, the Raman gain as a function of the distance and the effective fiber length of each DBP step need to be calculated by solving the differential equations of Raman amplification. The split-step DBP is performed only for transmission where the signal power is high.In comparison with solving the nonlinear Schrodinger equation (NLSE) for the total field of the WDM signal, solving the coupled NLSE requires a smaller step number and a lower sampling rate. In addition, the phase-locking between the local oscillators is not necessary for solving the coupled NLSE. The XPM compensation of WDM long-haul transmission by solving the coupled NLSE is experimentally demonstrated.At the optimum power level of fiber transmission, the total nonlinear phase shift is on the order of 1 radian. Therefore, for transoceanic fiber transmission systems which consist of many ((>)100) amplified fiber spans, the nonlinear effects in each span are weak. As a result, the optical waveform evolution is dominated by the dispersion. Taking advantage of the periodic waveform evolution in periodically dispersion managed fiber link, the DBP of K fiber spans can be folded into one span with K times the nonlinearity. This method can be called (")distance-folded DBP("). Under the weakly nonlinear assumption, the optical waveform repeats at locations where accumulated dispersions are identical. Consequently, the nonlinear behavior of the optical signal also repeats at locations of identical accumulative dispersion. Hence for a fiber link with arbitrary dispersion map, the DBP steps can be folded according to the accumulated dispersion. Experimental results show considerable savings in computation using this (")dispersion-folded DBP(") method. Simulation results show that the dramatically reduced computational load makes the nonlinearity-compensated dispersion-managed fiber link a competitive candidate for the next-generation transmission systems.
Show less - Date Issued
- 2011
- Identifier
- CFE0004492, ucf:49272
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004492
- Title
- Mode-Division Multiplexed Transmission in Few-mode Fibers.
- Creator
-
Bai, Neng, Li, Guifang, Christodoulides, Demetrios, Schulzgen, Axel, Abouraddy, Ayman, Phillips, Ronald, Ip, Ezra, University of Central Florida
- Abstract / Description
-
As a promising candidate to break the single-mode fiber capacity limit, mode-division multiplexing (MDM) explores the spatial dimension to increase transmission capacity in fiber-optic communication. Two linear impairments, namely loss and multimode interference, present fundamental challenges to implementing MDM. In this dissertation, techniques to resolve these two issues are presented.To de-multiplex signals subject to multimode interference in MDM, Multiple-Input-Multiple-Output (MIMO)...
Show moreAs a promising candidate to break the single-mode fiber capacity limit, mode-division multiplexing (MDM) explores the spatial dimension to increase transmission capacity in fiber-optic communication. Two linear impairments, namely loss and multimode interference, present fundamental challenges to implementing MDM. In this dissertation, techniques to resolve these two issues are presented.To de-multiplex signals subject to multimode interference in MDM, Multiple-Input-Multiple-Output (MIMO) processing using adaptive frequency-domain equalization (FDE) is proposed and investigated. Both simulations and experiments validate that FDE can reduce the algorithmic complexity significantly in comparison with the conventional time-domain equalization (TDE) while achieving similar performance as TDE. To further improve the performance of FDE, two modifications on traditional FDE algorithm are demonstrated. i) normalized adaptive FDE is applied to increase the convergence speed by 5 times; ii) master-slave carrier recovery is proposed to reduce the algorithmic complexity of phase estimation by number of modes.Although FDE can reduce the computational complexity of the MIMO processing, due to large mode group delay (MGD) of FMF link and block processing, the algorithm still requires enormous memory and high hardware complexity. In order to reduce the required tap length (RTL) of the equalizer, differential mode group delay compensated fiber (DMGDC) has been proposed. In this dissertation, the analytical expression for RTL is derived for DMGDC systems under the weak mode coupling assumption. Instead of depending on the overall MGD of the link in DMGD uncompensated (DMGDUC) systems, the RTL of DMGDC systems depend on the MGD of a single DMGDC fiber section. The theoretical and numerical results suggest that by using small compensation step-size, the RTL of DMGDC link can be reduced by 2 orders of magnitude compared to DMGDUC link. To compensate the loss of different modes, multimode EDFAs are presented with re-configurable multimode pumps. By tuning the mode content of the multimode pump, mode-dependent gain (MDG) can be controlled and equalized. A proto-type FM-EDFA which could support 2 LP modes was constructed. The experimental results show that by using high order mode pumps, the modal gain difference can be reduced. By applying both multimode EDFA and equalization techniques, 26.4Tb/s MDM-WDM transmission was successfully demonstrated.A brief summary and several possible future research directions conclude this dissertation.
Show less - Date Issued
- 2013
- Identifier
- CFE0004811, ucf:49751
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004811
- Title
- Digital Citizenship Tools for Cause-Based Campaigns: A Broadened Spectrum of Social Media Engagement and Participation-Scale Methodology.
- Creator
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Miller, Jennifer, Vie, Stephanie, Scott, Blake, Flammia, Madelyn, St. Amant, Kirk, University of Central Florida
- Abstract / Description
-
Digital Citizenship Tools for Cause-Based Campaigns: A Broadened Spectrum of Social Media Engagement and Participation-Scale Methodology develops and applies two new tools for understanding, measuring, and recursively adjusting small to medium-size social media-based philanthropic campaigns to better foster participation and engagement(-)in other words, democratic digital citizenship. First, a theoretical model is offered broadening current binary conceptions of success and failure or impact...
Show moreDigital Citizenship Tools for Cause-Based Campaigns: A Broadened Spectrum of Social Media Engagement and Participation-Scale Methodology develops and applies two new tools for understanding, measuring, and recursively adjusting small to medium-size social media-based philanthropic campaigns to better foster participation and engagement(-)in other words, democratic digital citizenship. First, a theoretical model is offered broadening current binary conceptions of success and failure or impact of campaigns, situating specific participant actions in social media on a spectrum. Then, from that model, a new methodology is provided to measure participation and engagement generated by campaign posts. Recommendations are also offered for recursively adjusting campaign posts to better foster democratic digital citizenship. These tools were developed from data generated by #TheFaceOffChallenge, a research project representative of a typical small to medium-size cause-based campaign. #TheFaceOffChallenge also serves as a sample for analysis illustrating how to use these tools. While explicating these tools, this dissertation explores a broad range of topics related to better understanding democratic digital citizenship: online philanthropy, awareness, and digital activism; viral and memetic transmission; tensions between consumption and creation of ideas, content, and knowledge; public(s), counterpublics, and counter-efforts; literacies and access for engagement and participation in algorithmic environments; and visual communication and semiotics.
Show less - Date Issued
- 2018
- Identifier
- CFE0007227, ucf:52214
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007227
- Title
- The Modern Church Communicates: Rhetoric and Hypertext in Church Website Design.
- Creator
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Palmer, Edward, Applen, John, Jones, Dan, Stephens, Sonia, University of Central Florida
- Abstract / Description
-
The Internet and the World Wide Web have supplanted many paper-based information systems. People turn to the web to locate local services in the same way they find ecommerce sites such as Amazon. Churches of all sizes must develop effective and attractive websites to attract new members and inform existing members. These two groups form distinct audiences that must be correctly targeted by the website content. Other churches may visit to gather ideas for their programs; they are a third group...
Show moreThe Internet and the World Wide Web have supplanted many paper-based information systems. People turn to the web to locate local services in the same way they find ecommerce sites such as Amazon. Churches of all sizes must develop effective and attractive websites to attract new members and inform existing members. These two groups form distinct audiences that must be correctly targeted by the website content. Other churches may visit to gather ideas for their programs; they are a third group of site visitors. Organization of hypertext on the web requires skills that are different than writing for print. Technical communicators possess those skills and can help others write better hypertext. This research examines eight churches that cross three categories: denomination, size, and location. The websites of the churches are analyzed from the standpoint of the reader and the technical communicator to determine their effectiveness in content, organization, and underlying structure of the webpages, and then consider if geography, size, or denomination account for the observed differences. Audience and message are lesser issues than organization of information and navigational guidance for the reader. No remarkable differences were observed based on size, geography, or denomination. The technical communicator can assist non-technical content producers in developing skills in organization and classification.
Show less - Date Issued
- 2017
- Identifier
- CFE0006635, ucf:51218
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006635
- Title
- Placing birds on a dynamic evolutionary map: Using digital tools to update the evolutionary metaphor of the "tree of life".
- Creator
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Stephens, Sonia, Dombrowski, Paul, Applen, John, Murphy, Patrick, Lindgren, Robb, University of Central Florida
- Abstract / Description
-
This dissertation describes and presents a new type of interactive visualization for communicating about evolutionary biology, the dynamic evolutionary map. This web-based tool utilizes a novel map-based metaphor to visualize evolution, rather than the traditional (")tree of life.(") The dissertation begins with an analysis of the conceptual affordances of the traditional tree of life as the dominant metaphor for evolution. Next, theories from digital media, visualization, and cognitive...
Show moreThis dissertation describes and presents a new type of interactive visualization for communicating about evolutionary biology, the dynamic evolutionary map. This web-based tool utilizes a novel map-based metaphor to visualize evolution, rather than the traditional (")tree of life.(") The dissertation begins with an analysis of the conceptual affordances of the traditional tree of life as the dominant metaphor for evolution. Next, theories from digital media, visualization, and cognitive science research are synthesized to support the assertion that digital media tools can extend the types of visual metaphors we use in science communication in order to overcome conceptual limitations of traditional metaphors. These theories are then applied to a specific problem of science communication, resulting in the dynamic evolutionary map.Metaphor is a crucial part of scientific communication, and metaphor-based scientific visualizations, models, and analogies play a profound role in shaping our ideas about the world around us. Users of the dynamic evolutionary map interact with evolution in two ways: by observing the diversification of bird orders over time and by examining the evidence for avian evolution at several places in evolutionary history. By combining these two types of interaction with a non-traditional map metaphor, evolution is framed in a novel way that supplements traditional metaphors for communicating about evolution. This reframing in turn suggests new conceptual affordances to users who are learning about evolution. Empirical testing of the dynamic evolutionary map by biology novices suggests that this approach is successful in communicating evolution differently than in existing tree-based visualization methods. Results of evaluation of the map by biology experts suggest possibilities for future enhancement and testing of this visualization that would help refine these successes. This dissertation represents an important step forward in the synthesis of scientific, design, and metaphor theory, as applied to a specific problem of science communication. The dynamic evolutionary map demonstrates that these theories can be used to guide the construction of a visualization for communicating a scientific concept in a way that is both novel and grounded in theory. There are several potential applications in the fields of informal science education, formal education, and evolutionary biology for the visualization created in this dissertation. Moreover, the approach suggested in this dissertation can potentially be extended into other areas of science and science communication. By placing birds onto the dynamic evolutionary map, this dissertation points to a way forward for visualizing science communication in the future.
Show less - Date Issued
- 2012
- Identifier
- CFE0004639, ucf:49898
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004639
- Title
- An Analysis of the Readiness and Confidence of High School Administrators to Provide Instructional Leadership in Digital School Environments.
- Creator
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Shepherd, Andrew, Taylor, Rosemarye, Doherty, Walter, Johnson, Jerry, Border, Harold, University of Central Florida
- Abstract / Description
-
The purpose of this study was to analyze the perceived knowledge and confidence of high school administrators to lead in a digital school environment. This study utilized an exploratory mixed-methods case study analysis along with the 62-item Digital Instructional Leadership Readiness Instrument (DILRI)(&)copy; to measure school administrators' knowledge and confidence to lead in a digital school environment. High school administrators within the target school district were requested to...
Show moreThe purpose of this study was to analyze the perceived knowledge and confidence of high school administrators to lead in a digital school environment. This study utilized an exploratory mixed-methods case study analysis along with the 62-item Digital Instructional Leadership Readiness Instrument (DILRI)(&)copy; to measure school administrators' knowledge and confidence to lead in a digital school environment. High school administrators within the target school district were requested to complete the DILRI(&)copy; at two separate points in time: September 2016 and June 2017. Based on these two administrations, this study's six Research Questions were answered. Research Questions 1, 2, 3, 4, and 6 were addressed quantitatively using descriptive statistics, along with two MANOVA analyses for Research Question 6. Research Question 5 was answered qualitatively by examining open-ended responses found within the DILRI(&)copy;. Based on the data collected, Experience Supervising Others and Colleagues were two factors ranked highest by administrators as influencing their knowledge and confidence. Additionally, high school administrators perceive themselves to be knowledge and confident in recognizing Student Engagement and Student Collaboration, and in developing digital school culture factors of Leadership Teams, Empowering Teachers, and Shared Vision. Overall means increased for knowledge and confidence on each scale between the September 2016 and June 2017 DILRI(&)copy; administrations. Much research relating to the digital school environment has only focused on the preparation required of teachers; therefore, this study provides administrators, directors, school boards, superintendents, and other school district leaders with relevant information relating to the self-reported readiness of high school administrators to lead in a digital school environment.
Show less - Date Issued
- 2017
- Identifier
- CFE0007295, ucf:52173
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007295
- Title
- ANALYSIS OF TIME SYNCHRONIZATION ERRORS IN HIGH DATA RATE ULTRAWIDEBAND ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING DATA LINKS.
- Creator
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Bates, Lakesha, Jones, W. Linwood, University of Central Florida
- Abstract / Description
-
Emerging Ultra Wideband (UWB) Orthogonal Frequency Division Multiplexing (OFDM) systems hold the promise of delivering wireless data at high speeds, exceeding hundreds of megabits per second over typical distances of 10 meters or less. The purpose of this Thesis is to estimate the timing accuracies required with such systems in order to achieve Bit Error Rates (BER) of the order of magnitude of 10-12 and thereby avoid overloading the correction of irreducible errors due to misaligned timing...
Show moreEmerging Ultra Wideband (UWB) Orthogonal Frequency Division Multiplexing (OFDM) systems hold the promise of delivering wireless data at high speeds, exceeding hundreds of megabits per second over typical distances of 10 meters or less. The purpose of this Thesis is to estimate the timing accuracies required with such systems in order to achieve Bit Error Rates (BER) of the order of magnitude of 10-12 and thereby avoid overloading the correction of irreducible errors due to misaligned timing errors to a small absolute number of bits in error in real-time relative to a data rate of hundreds of megabits per second. Our research approach involves managing bit error rates through identifying maximum timing synchronization errors. Thus, it became our research goal to determine the timing accuracies required to avoid operation of communication systems within the asymptotic region of BER flaring at low BERs in the resultant BER curves. We propose pushing physical layer bit error rates to below 10-12 before using forward error correction (FEC) codes. This way, the maximum reserve is maintained for the FEC hardware to correct for burst as well as recurring bit errors due to corrupt bits caused by other than timing synchronization errors.
Show less - Date Issued
- 2004
- Identifier
- CFE0000197, ucf:46173
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000197
- Title
- GUIDELINES FOR TWENTY-FIRST CENTURY INSTRUCTIONAL DESIGN AND TECHNOLOGY USE: TECHNOLOGIES' INFLUENCE ON THE BRAIN.
- Creator
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Gabriel, Jennifer, Flammia, Madelyn, University of Central Florida
- Abstract / Description
-
The increasingly global environment has spurred the economy in the United States as well as the economies in nearly every other nation. Although the U.S. remains the world leader in the global economy, research shows that the United States is at risk of losing its place as the world leader in science and innovation. Policymakers have recognized the need for research addressing global competitiveness. President Bush signed the America Competes Act, which calls for increased investment in...
Show moreThe increasingly global environment has spurred the economy in the United States as well as the economies in nearly every other nation. Although the U.S. remains the world leader in the global economy, research shows that the United States is at risk of losing its place as the world leader in science and innovation. Policymakers have recognized the need for research addressing global competitiveness. President Bush signed the America Competes Act, which calls for increased investment in innovation and education to improve U.S. competitiveness and President Barack Obama has named a platform, "Science, Technology and Innovation for a New Generation" which will extend and prioritize the efforts to improve math and science education. K‐12 U.S. students are graduating from high school unprepared to pursue degrees in science, technology, engineering and math (STEM) in college. Without STEM degrees they will be unable to pursue technology jobs after graduation. Statistics show that the U.S. is failing to produce as many graduates in STEM as other countries. In an increasingly global world, without graduates in STEM courses the U.S. is at risk of losing its position as the economic world leader. Government, industry and academia all agree that the U.S. needs to address education on a K‐12 level to ensure that U.S. students are equipped with twenty‐first century skills to compete in a twenty‐first century global economy. Twenty‐first century students are different from students of previous generations. Researchers argue that changes in the environment, specifically an increased exposure to technology, have changed the brains of twenty‐first century students; twenty‐first century students learn differently. However, twenty‐first century students are being taught with an instructional curriculum that was designed for a previous generation that did not have the same exposure to technology. This is causing a digital‐divide that is hindering the achievement of students. The instructional curriculum needs to be updated to meet the needs of twenty‐first century students. This thesis addresses this need from a technical communication perspective by arguing that the instructional design of twenty‐first century learning materials should be improved by adhering to guidelines for twenty‐first century learning characteristics and twenty‐first century technology use. The guidelines support a national goal to improve K‐12 achievement in order to increase U.S. STEM graduates and increase the U.S.'s ability to compete in a global economy.
Show less - Date Issued
- 2009
- Identifier
- CFE0002704, ucf:48183
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002704
- Title
- "ANALYZING THE EFFECTS OF SINGLE-SOURCING METHODOLOGIES ON THE ROLE OF THE TECHNICAL COMMUNICATOR".
- Creator
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Boehl, Jeremy, Applen, J.D., University of Central Florida
- Abstract / Description
-
This thesis discusses the specific effects of single sourcing methodologies on the role of the technical communicator, his or her job responsibilities, qualifications, collaboration with coworkers, employee and employer expectations, and the effects on career progression. The methodologies discussed included all types of single sourcing methods for technical documentation (such as XML-based), advanced and non-advanced Content Management Systems (CMS), and Digital Asset Management (DAM)...
Show moreThis thesis discusses the specific effects of single sourcing methodologies on the role of the technical communicator, his or her job responsibilities, qualifications, collaboration with coworkers, employee and employer expectations, and the effects on career progression. The methodologies discussed included all types of single sourcing methods for technical documentation (such as XML-based), advanced and non-advanced Content Management Systems (CMS), and Digital Asset Management (DAM) systems. Other topics explored are an overview of single sourcing for technical documentation, a comparison of the "craftsman model" to the current trend of single sourcing and structured content, specific effects on technical communicators such as role changes, the effects of incorporating XML into a technical communicator's daily work environment, and the effects of other emerging technologies such as advanced CMS and DAM systems on technical communicators. General findings include that the practice of single sourcing, whether a positive or negative development, has continued and likely will continue to increase in technical communication groups within organizations. Single sourcing, especially for dynamic, customized content is also increasing because of the current marketplace, but works best via the use of a CMS and other systems used by large organizations. Single sourcing is also best implemented after extensive strategic planning and training of employees. Many technical communicators will have to accept new roles and positions, the direction of which is greatly impacted by the extent of their skills. Recommendations are made for additional research on the effects of single sourcing implementation on the technical communicator, and how to adapt to changes. Additional research is also needed on XML, DITA (Darwinian Information Typing Architecture), and DAM systems, all related specifically to technical communication.
Show less - Date Issued
- 2006
- Identifier
- CFE0001302, ucf:47031
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001302
- Title
- LIQUID CRYSTAL OPTICS FOR COMMUNICATIONS, SIGNAL PROCESSING AND 3-D MICROSCOPIC IMAGING.
- Creator
-
Khan, Sajjad, Riza, Nabeel, University of Central Florida
- Abstract / Description
-
This dissertation proposes, studies and experimentally demonstrates novel liquid crystal (LC) optics to solve challenging problems in RF and photonic signal processing, freespace and fiber optic communications and microscopic imaging. These include free-space optical scanners for military and optical wireless applications, variable fiber-optic attenuators for optical communications, photonic control techniques for phased array antennas and radar, and 3-D microscopic imaging. At the heart of...
Show moreThis dissertation proposes, studies and experimentally demonstrates novel liquid crystal (LC) optics to solve challenging problems in RF and photonic signal processing, freespace and fiber optic communications and microscopic imaging. These include free-space optical scanners for military and optical wireless applications, variable fiber-optic attenuators for optical communications, photonic control techniques for phased array antennas and radar, and 3-D microscopic imaging. At the heart of the applications demonstrated in this thesis are LC devices that are non-pixelated and can be controlled either electrically or optically. Instead of the typical pixel-by-pixel control as is custom in LC devices, the phase profile across the aperture of these novel LC devices is varied through the use of high impedance layers. Due to the presence of the high impedance layer, there forms a voltage gradient across the aperture of such a device which results in a phase gradient across the LC layer which in turn is accumulated by the optical beam traversing through this LC device. The geometry of the electrical contacts that are used to apply the external voltage will define the nature of the phase gradient present across the optical beam. In order to steer a laser beam in one angular dimension, straight line electrical contacts are used to form a one dimensional phase gradient while an annular electrical contact results in a circularly symmetric phase profile across the optical beam making it suitable for focusing the optical beam. The geometry of the electrical contacts alone is not sufficient to form the linear and the quadratic phase profiles that are required to either deflect or focus an optical beam. Clever use of the phase response of a typical nematic liquid crystal (NLC) is made such that the linear response region is used for the angular beam deflection while the high voltage quadratic response region is used for focusing the beam. Employing an NLC deflector, a device that uses the linear angular deflection, laser beam steering is demonstrated in two orthogonal dimensions whereas an NLC lens is used to address the third dimension to complete a three dimensional (3-D) scanner. Such an NLC deflector was then used in a variable optical attenuator (VOA), whereby a laser beam coupled between two identical single mode fibers (SMF) was mis-aligned away from the output fiber causing the intensity of the output coupled light to decrease as a function of the angular deflection. Since the angular deflection is electrically controlled, hence the VOA operation is fairly simple and repeatable. An extension of this VOA for wavelength tunable operation is also shown in this dissertation. A LC spatial light modulator (SLM) that uses a photo-sensitive high impedance electrode whose impedance can be varied by controlling the light intensity incident on it, is used in a control system for a phased array antenna. Phase is controlled on the Write side of the SLM by controlling the intensity of the Write laser beam which then is accessed by the Read beam from the opposite side of this reflective SLM. Thus the phase of the Read beam is varied by controlling the intensity of the Write beam. A variable fiber-optic delay line is demonstrated in the thesis which uses wavelength sensitive and wavelength insensitive optics to get both analog as well as digital delays. It uses a chirped fiber Bragg grating (FBG), and a 1xN optical switch to achieve multiple time delays. The switch can be implemented using the 3-D optical scanner mentioned earlier. A technique is presented for ultra-low loss laser communication that uses a combination of strong and weak thin lens optics. As opposed to conventional laser communication systems, the Gaussian laser beam is prevented from diverging at the receiving station by using a weak thin lens that places the transmitted beam waist mid-way between a symmetrical transmitter-receiver link design thus saving prime optical power. LC device technology forms an excellent basis to realize such a large aperture weak lens. Using a 1-D array of LC deflectors, a broadband optical add-drop filter (OADF) is proposed for dense wavelength division multiplexing (DWDM) applications. By binary control of the drive signal to the individual LC deflectors in the array, any optical channel can be selectively dropped and added. For demonstration purposes, microelectromechanical systems (MEMS) digital micromirrors have been used to implement the OADF. Several key systems issues such as insertion loss, polarization dependent loss, wavelength resolution and response time are analyzed in detail for comparison with the LC deflector approach. A no-moving-parts axial scanning confocal microscope (ASCM) system is designed and demonstrated using a combination of a large diameter LC lens and a classical microscope objective lens. By electrically controlling the 5 mm diameter LC lens, the 633 nm wavelength focal spot is moved continuously over a 48 ƒÝm range with measured 3-dB axial resolution of 3.1 ƒÝm using a 0.65 numerical aperture (NA) micro-objective lens. The ASCM is successfully used to image an Indium Phosphide twin square optical waveguide sample with a 10.2 ƒÝm waveguide pitch and 2.3 ƒÝm height and width. Using fine analog electrical control of the LC lens, a super-fine sub-wavelength axial resolution of 270 nm is demonstrated. The proposed ASCM can be useful in various precision three dimensional imaging and profiling applications.
Show less - Date Issued
- 2005
- Identifier
- CFE0000750, ucf:46596
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000750
