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- Title
- THE EFFECTS OF VIDEO FRAME DELAY AND SPATIAL ABILITY ON THE OPERATION OF MULTIPLE SEMIAUTONOMOUS AND TELE-OPERATED ROBOTS.
- Creator
-
Sloan, Jared, Stanney, Kay, University of Central Florida
- Abstract / Description
-
The United States Army has moved into the 21st century with the intent of redesigning not only the force structure but also the methods by which we will fight and win our nation's wars. Fundamental in this restructuring is the development of the Future Combat Systems (FCS). In an effort to minimize exposure of front line soldiers the future Army will utilize unmanned assets for both information gathering and when necessary engagements. Yet this must be done judiciously, as the bandwidth for...
Show moreThe United States Army has moved into the 21st century with the intent of redesigning not only the force structure but also the methods by which we will fight and win our nation's wars. Fundamental in this restructuring is the development of the Future Combat Systems (FCS). In an effort to minimize exposure of front line soldiers the future Army will utilize unmanned assets for both information gathering and when necessary engagements. Yet this must be done judiciously, as the bandwidth for net-centric warfare is limited. The implication is that the FCS must be designed to leverage bandwidth in a manner that does not overtax computational resources. In this study alternatives for improving human performance during operation of teleoperated and semi-autonomous robots were examined. It was predicted that when operating both types of robots, frame delay of the semi-autonomous robot would improve performance because it would allow operators to concentrate on the constant workload imposed by the teleoperated while only allocating resources to the semi-autonomous during critical tasks. An additional prediction was that operators with high spatial ability would perform better than those with low spatial ability, especially when operating an aerial vehicle. The results can not confirm that frame delay has a positive effect on operator performance, though power may have been an issue, but clearly show that spatial ability is a strong predictor of performance on robotic asset control, particularly with aerial vehicles. In operating the UAV, the high spatial group was, on average, 30% faster, lazed 12% more targets, and made 43% more location reports than the low spatial group. The implications of this study indicate that system design should judiciously manage workload and capitalize on individual ability to improve performance and are relevant to system designers, especially in the military community.
Show less - Date Issued
- 2005
- Identifier
- CFE0000430, ucf:46379
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000430
- Title
- A STUDY OF SYNGAS OXIDATION AT HIGH PRESSURES AND LOW TEMPERATURES.
- Creator
-
Kalitan, Danielle, Petersen, Eric, University of Central Florida
- Abstract / Description
-
Ignition and oxidation characteristics of CO/H2, H2/O2 and CO/H2/CH4/CO2/Ar fuel blends in air were studied using both experimental and computer simulation methods. Shock-tube experiments were conducted behind reflected shock waves at intermediate temperatures (825
Show moreIgnition and oxidation characteristics of CO/H2, H2/O2 and CO/H2/CH4/CO2/Ar fuel blends in air were studied using both experimental and computer simulation methods. Shock-tube experiments were conducted behind reflected shock waves at intermediate temperatures (825 < T < 1400 K) for a wide range of pressures (1 < P < 45 atm). Results of this study provide the first undiluted fuel-air ignition delay time experiments to cover such a wide range of syngas mixture compositions over the stated temperature range. Emission in the form of chemiluminescence from the hydroxyl radical (OH*) transition near 307 nm and the pressure behind the reflected shock wave were used to monitor reaction progress from which ignition delay times were determined. In addition to the experimental analysis, chemical kinetics calculations were completed to compare several chemical kinetics mechanisms to the new experimental results. Overall, the models were in good agreement with the shock-tube data, especially at higher temperatures and lower pressures, yet there were some differences between the models at higher pressures and the lowest temperatures, in some cases by as much as a factor of five. In order to discern additional information from the chemical kinetics mechanisms regarding their response to a wide range of experimental conditions, ignition delay time and reaction rate sensitivity analyses were completed at higher and lower temperatures and higher and lower pressures. These two sensitivity analyses allow for the identification of the key reactions responsible for ignition. The results of the sensitivity analysis indicate that the ignition-enhancing reaction H + O2 = O + OH and hydrogen oxidation kinetics in general were most important regardless of mixture composition, temperature or pressure. However, lower-temperature, higher-pressure ignition delay time results indicate additional influence from HO2- and CO- containing reactions, particularly the well-known H + O + M = HO2 + M reaction and also the CO + O + M = CO2 + M and CO + HO2 = CO2 + OH reactions. Differences in the rates of the CO-related reactions are shown to be the cause of some of the discrepancies amongst the various models at elevated pressures. However, the deviation between the models and the experimental data at the lowest temperatures could not be entirely explained by discrepancies in the current rates of the reactions contained within the mechanisms. Additional calculations were therefore performed to gain further understanding regarding the opposing ignition behavior for calculated and measured ignition delay time results. Impurities, friction induced ionization, static charge accumulation, boundary layer effects, wall reaction effects, and revised chemical kinetics were all considered to be possible mechanisms for the model and measured data disparity. For the case of wall-reaction effects, additional shock-tube experiments were conducted. For the remaining effects listed above, only detailed calculations were conducted. Results from this preliminary anomaly study are at this time inconclusive, but likely avenues for future study were identified. Additional kinetics calculations showed that the large difference between the experimental data and the chemical kinetics models predictions at low temperatures can be explained by at least one missing reaction relevant to low-temperature and high-pressure experimental conditions involving the formation of H2O2, although further study beyond the scope of this thesis is required to prove this hypothesis both theoretically and experimentally.
Show less - Date Issued
- 2007
- Identifier
- CFE0001862, ucf:47414
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001862
- Title
- DESIGN AND OPTIMIZATION OF NANOSTRUCTURED OPTICAL FILTERS.
- Creator
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Brown, Jeremiah, Moharam, Jim, University of Central Florida
- Abstract / Description
-
Optical filters encompass a vast array of devices and structures for a wide variety of applications. Generally speaking, an optical filter is some structure that applies a designed amplitude and phase transform to an incident signal. Different classes of filters have vastly divergent characteristics, and one of the challenges in the optical design process is identifying the ideal filter for a given application and optimizing it to obtain a specific response. In particular, it is highly...
Show moreOptical filters encompass a vast array of devices and structures for a wide variety of applications. Generally speaking, an optical filter is some structure that applies a designed amplitude and phase transform to an incident signal. Different classes of filters have vastly divergent characteristics, and one of the challenges in the optical design process is identifying the ideal filter for a given application and optimizing it to obtain a specific response. In particular, it is highly advantageous to obtain a filter that can be seamlessly integrated into an overall device package without requiring exotic fabrication steps, extremely sensitive alignments, or complicated conversions between optical and electrical signals. This dissertation explores three classes of nano-scale optical filters in an effort to obtain different types of dispersive response functions. First, dispersive waveguides are designed using a sub-wavelength periodic structure to transmit a single TE propagating mode with very high second order dispersion. Next, an innovative approach for decoupling waveguide trajectories from Bragg gratings is outlined and used to obtain a uniform second-order dispersion response while minimizing fabrication limitations. Finally, high Q-factor microcavities are coupled into axisymmetric pillar structures that offer extremely high group delay over very narrow transmission bandwidths. While these three novel filters are quite diverse in their operation and target applications, they offer extremely compact structures given the magnitude of the dispersion or group delay they introduce to an incident signal. They are also designed and structured as to be formed on an optical wafer scale using standard integrated circuit fabrication techniques. A number of frequency-domain numerical simulation methods are developed to fully characterize and model each of the different filters. The complete filter response, which includes the dispersion and delay characteristics and optical coupling, is used to evaluate each filter design concept. However, due to the complex nature of the structure geometries and electromagnetic interactions, an iterative optimization approach is required to improve the structure designs and obtain a suitable response. To this end, a Particle Swarm Optimization algorithm is developed and applied to the simulated filter responses to generate optimal filter designs.
Show less - Date Issued
- 2008
- Identifier
- CFE0002502, ucf:47678
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002502
- Title
- EPIDEMIOLOGICAL MODELS FOR MUTATING PATHOGENS WITH TEMPORARY IMMUNITY.
- Creator
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Singh, Neeta, Rollins, David, University of Central Florida
- Abstract / Description
-
Significant progress has been made in understanding different scenarios for disease transmissions and behavior of epidemics in recent years. A considerable amount of work has been done in modeling the dynamics of diseases by systems of ordinary differential equations. But there are very few mathematical models that deal with the genetic mutations of a pathogen. In-fact, not much has been done to model the dynamics of mutations of pathogen explaining its effort to escape the host's immune...
Show moreSignificant progress has been made in understanding different scenarios for disease transmissions and behavior of epidemics in recent years. A considerable amount of work has been done in modeling the dynamics of diseases by systems of ordinary differential equations. But there are very few mathematical models that deal with the genetic mutations of a pathogen. In-fact, not much has been done to model the dynamics of mutations of pathogen explaining its effort to escape the host's immune defense system after it has infected the host. In this dissertation we develop an SIR model with variable infection age for the transmission of a pathogen that can mutate in the host to produce a second infectious mutant strain. We assume that there is a period of temporary immunity in the model. A temporary immunity period along with variable infection age leads to an integro-differential-difference model. Previous efforts on incorporating delays in epidemic models have mainly concentrated on inclusion of latency periods (this assumes that the force of infection at a present time is determined by the number of infectives in the past). We begin with reviewing some basic models. These basic models are the building blocks for the later, more detailed models. Next we consider the model for mutation of pathogen and discuss its implications. Finally, we improve this model for mutation of pathogen by incorporating delay induced by temporary immunity. We examine the influence of delay as we establish the existence, and derive the explicit forms of disease-free, boundary and endemic equilibriums. We will also investigate the local stability of each of these equilibriums. The possibility of Hopf bifurcation using delay as the bifurcation parameter is studied using both analytical and numerical solutions.
Show less - Date Issued
- 2006
- Identifier
- CFE0001043, ucf:46801
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001043
- Title
- SPORTS MASSAGE RESEARCH PROTOCOLS AND INDUSTRY STANDARDS.
- Creator
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Kest, Amber, Valdes, Anna, University of Central Florida
- Abstract / Description
-
The purpose of this study was to determine which MT techniques current licensed massage therapists practicing sports massage are using to treat delayed onset muscle soreness (DOMS) by conducting an anonymous online survey of practicing sports massage therapists. The secondary purpose was to determine if previous sports massage research protocols match current practices in sports massage to treat DOMS. There were 85 anonymous respondents ranging in age from 24 to 74 years with a mean age of 44...
Show moreThe purpose of this study was to determine which MT techniques current licensed massage therapists practicing sports massage are using to treat delayed onset muscle soreness (DOMS) by conducting an anonymous online survey of practicing sports massage therapists. The secondary purpose was to determine if previous sports massage research protocols match current practices in sports massage to treat DOMS. There were 85 anonymous respondents ranging in age from 24 to 74 years with a mean age of 44.5 years. Participants included 55 female (65.5%) and 29 male (34.5%) therapists. Professional experience ranged from 4 years or less to more than 20 years, and the majority reported having training specific to sports massage. Previous research methods have placed an overwhelming emphasis on effleurage and petrissage in the treatment protocols to test the effects of massage on DOMS. However, practicing therapists rely on many more techniques and modalities when giving sports massage treatments for DOMS. On a scale of 1 to 5 respondents rated the importance of effleurage strokes in their sports massage treatment at 3.3, petrissage strokes averaged 3.4, friction 3.3, and tapotement ranked slightly lower with a weighted average of 2.1. Sixty six percent of respondents reported that they use stretching techniques often or always. Myofascial release techniques are used sometimes or often for 65% of the respondents, but fewer utilize manual lymphatic drainage in their sports massage. Additional techniques besides those mentioned in the survey are used by 64% of the respondents.
Show less - Date Issued
- 2015
- Identifier
- CFH0004846, ucf:45476
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004846
- Title
- NUMERICAL MODELING OF THE SHOCK TUBE FLOW FIELDS BEFORE ANDDURING IGNITION DELAY TIME EXPERIMENTS AT PRACTICAL CONDITIONS.
- Creator
-
lamnaouer, mouna, Kassab, Alain, University of Central Florida
- Abstract / Description
-
An axi-symmetric shock-tube model has been developed to simulate the shock-wave propagation and reflection in both non-reactive and reactive flows. Simulations were performed for the full shock-tube geometry of the high-pressure shock tube facility at Texas A&M University. Computations were carried out in the CFD solver FLUENT based on the finite volume approach and the AUSM+ flux differencing scheme. Adaptive mesh refinement (AMR) algorithm was applied to the time-dependent flow fields to...
Show moreAn axi-symmetric shock-tube model has been developed to simulate the shock-wave propagation and reflection in both non-reactive and reactive flows. Simulations were performed for the full shock-tube geometry of the high-pressure shock tube facility at Texas A&M University. Computations were carried out in the CFD solver FLUENT based on the finite volume approach and the AUSM+ flux differencing scheme. Adaptive mesh refinement (AMR) algorithm was applied to the time-dependent flow fields to accurately capture and resolve the shock and contact discontinuities as well as the very fine scales associated with the viscous and reactive effects. A conjugate heat transfer model has been incorporated which enhanced the credibility of the simulations. The multi-dimensional, time-dependent numerical simulations resolved all of the relevant scales, ranging from the size of the system to the reaction zone scale. The robustness of the numerical model and the accuracy of the simulations were assessed through validation with the analytical ideal shock-tube theory and experimental data. The numerical method is first applied to the problem of axi-symmetric inviscid flow then viscous effects are incorporated through viscous modeling. The non-idealities in the shock tube have been investigated and quantified, notably the non-ideal transient behavior in the shock tube nozzle section, heat transfer effects from the hot gas to the shock tube side walls, the reflected shock/boundary layer interactions or what is known as bifurcation, and the contact surface/bifurcation interaction resulting into driver gas contamination. The non-reactive model is shown to be capable of accurately simulating the shock and expansion wave propagations and reflections as well as the flow non-uniformities behind the reflected shock wave. Both the inviscid and the viscous non-reactive models provided a baseline for the combustion model iii which involves elementary chemical reactions and requires the coupling of the chemistry with the flow fields adding to the complexity of the problem and thereby requiring tremendous computational resources. Combustion modeling focuses on the ignition process behind the reflected shock wave in undiluted and diluted Hydrogen test gas mixtures. Accurate representation of the Shock –tube reactive flow fields is more likely to be achieved by the means of the LES model in conjunction with the EDC model. The shock-tube CFD model developed herein provides valuable information to the interpretation of the shock-tube experimental data and to the understanding of the impact the facility-dependent non-idealities can have on the ignition delay time measurements.
Show less - Date Issued
- 2010
- Identifier
- CFE0003011, ucf:48366
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003011
- Title
- Chaotification as a Means of Broadband Vibration Energy Harvesting with Piezoelectric Materials.
- Creator
-
Geiyer, Daniel, Kauffman, Jeffrey L., Das, Tuhin, Moslehy, Faissal, Shivamoggi, Bhimsen, University of Central Florida
- Abstract / Description
-
Computing advances and component miniaturization in circuits coupled with stagnating battery technology have fueled growth in the development of high efficiency energy harvesters. Vibration-to-electricity energy harvesting techniques have been investigated extensively for use in sensors embedded in structures or in hard-to-reach locations like turbomachinery, surgical implants, and GPS animal trackers. Piezoelectric materials are commonly used in harvesters as they possess the ability to...
Show moreComputing advances and component miniaturization in circuits coupled with stagnating battery technology have fueled growth in the development of high efficiency energy harvesters. Vibration-to-electricity energy harvesting techniques have been investigated extensively for use in sensors embedded in structures or in hard-to-reach locations like turbomachinery, surgical implants, and GPS animal trackers. Piezoelectric materials are commonly used in harvesters as they possess the ability to convert strain energy directly into electrical energy and can work concurrently as actuators for damping applications. The prototypical harvesting system places two piezoelectric patches on both sides of the location of maximum strain on a cantilever beam. While efficient around resonance, performance drops dramatically should the driving frequency drift away from the beam's fundamental frequency. To date, researchers have worked to improve harvesting capability by modifying material properties, using alternative geometries, creating more efficient harvesting circuits, and inducing nonlinearities. These techniques have partially mitigated the resonance excitation dependence for vibration-based harvesting, but much work remains.In this dissertation, an induced nonlinearity destabilizes a central equilibrium point, resulting in a bistable potential function governing the cantilever beam system. Depending on the environment, multiple stable solutions are possible and can coexist. Typically, researchers neglect chaos and assume that with enough energy in the ambient environment, large displacement trajectories can exist uniquely. When subjected to disturbances a system can fall to coexistent lower energy solutions including aperiodic, chaotic oscillations. Treating chaotic motion as a desirable behavior of the system allows frequency content away from resonance to produce motion about a theoretically infinite number of unstable periodic orbits that can be stabilized through control. The extreme sensitivity to initial conditions exhibited by chaotic systems paired with a pole placement control strategy pioneered by Ott, Grebogi, and Yorke permits small perturbations to an accessible system parameter to alter the system response dramatically. Periodic perturbation of the system trajectories in the vicinity of isolated unstable orbit points can therefore stabilize low-energy chaotic oscillations onto larger trajectory orbits more suitable for energy harvesting.The periodic perturbation-based control method rids the need of a system model. It only requires discrete displacement, velocity, or voltage time series data of the chaotic system driven by harmonic excitation. While the analysis techniques are not fundamentally limited to harmonic excitation, this condition permits the use of standard discrete mapping techniques to isolate periodic orbits of interest. Local linear model fits characterize the orbit and admit the necessary control perturbation calculations from the time series data.This work discusses the feasibility of such a method for vibration energy harvesting, displays stable solutions under various control algorithms, and implements a hybrid bench-top experiment using MATLAB and LabVIEW FPGA. In conclusion, this work discusses the limitations for wide-scale use and addresses areas of further work; both with respect to chaotic energy harvesting and parallel advances required within the field as a whole.
Show less - Date Issued
- 2017
- Identifier
- CFE0006878, ucf:51718
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006878
- Title
- METHANE AND DIMETHYL ETHER OXIDATION AT ELEVATED TEMPERATURES AND PRESSURE.
- Creator
-
Zinner, Christopher, Basu, Saptarshi, University of Central Florida
- Abstract / Description
-
Autoignition and oxidation of two Methane (CH4) and Dimethyl Ether (CH3OCH3 or DME) mixtures in air were studied in shock tubes over a wide range of equivalence ratios at elevated temperatures and pressures. These experiments were conducted in the reflected shock region with pressures ranging from 0.8 to 35.7 atmospheres, temperatures ranging from 913 to 1650 K, and equivalence ratios of 2.0, 1.0, 0.5, and 0.3. Ignition delay times were obtained from shock-tube endwall pressure traces for...
Show moreAutoignition and oxidation of two Methane (CH4) and Dimethyl Ether (CH3OCH3 or DME) mixtures in air were studied in shock tubes over a wide range of equivalence ratios at elevated temperatures and pressures. These experiments were conducted in the reflected shock region with pressures ranging from 0.8 to 35.7 atmospheres, temperatures ranging from 913 to 1650 K, and equivalence ratios of 2.0, 1.0, 0.5, and 0.3. Ignition delay times were obtained from shock-tube endwall pressure traces for fuel mixtures of CH4/CH3OCH3 in ratios of 80/20 percent volume and 60/40 percent volume, respectively. Close examination of the data revealed that energy release from the mixture is occurring in the time between the arrival of the incident shock wave and the ignition event. An adjustment scheme for temperature and pressure was devised to account for this energy release and its effect on the ignition of the mixture. Two separate ignition delay correlations were developed for these pressure- and temperature-adjusted data. These correlations estimate ignition delay from known temperature, pressure, and species mole fractions of methane, dimethyl ether, and air (0.21 O2 + 0.79 N2). The first correlation was developed for ignition delay occurring at temperatures greater than or equal to 1175 K and pressures ranging from 0.8 to 35.3 atm. The second correlation was developed for ignition delay occurring at temperatures less than or equal to 1175 K and pressures ranging from 18.5 to 40.0 atm. Overall good agreement was found to exist between the two correlations and the data of these experiments. Findings of these experiments also include that with pressures at or below ten atm, increased concentrations of dimethyl ether will consistently produce faster ignition times. At pressures greater than ten atmospheres it is possible for fuel rich mixtures with lower concentrations of dimethyl ether to give the fastest ignition times. This work represents the most thorough shock tube investigation for oxidation of methane with high concentration levels of dimethyl ether at gas turbine engine relevant temperatures and pressures. The findings of this study should serve as a validation for detailed chemical kinetics mechanisms.
Show less - Date Issued
- 2008
- Identifier
- CFE0002096, ucf:47539
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002096
- Title
- Holding off on the fun stuff: Academic media multitasking and binge watching among college students.
- Creator
-
Merrill, Kelly, Rubenking, Bridget, Kinnally, William, Sellnow, Deanna, University of Central Florida
- Abstract / Description
-
College students are often faced with the temptation of engaging in academic media multitasking and binge watching or completing their academic coursework in a timely and effective manner. A quantitative survey (N = 651) explored trait individual differences in self-control and academic delay of gratification and situational individual differences in enjoyment, reward, procrastination, regret, and guilt as predictors of academic media multitasking frequency, binge watching frequency, and...
Show moreCollege students are often faced with the temptation of engaging in academic media multitasking and binge watching or completing their academic coursework in a timely and effective manner. A quantitative survey (N = 651) explored trait individual differences in self-control and academic delay of gratification and situational individual differences in enjoyment, reward, procrastination, regret, and guilt as predictors of academic media multitasking frequency, binge watching frequency, and binge watching duration. Stepwise regressions reveal that self-control is not a predictor of these media behaviors, while age and greater enjoyment were the only predictors of academic media multitasking and gender and greater enjoyment were the only predictors of binge watching duration. On the other hand, the other five variables provided insight on what predicted binge watching frequency: academic delay of gratification, reward, procrastination, regret, and guilt. Greater self-control also led to greater academic delay of gratification. Lastly, there were small positive correlations between all of the media behaviors except for academic media multitasking and binge watching frequency. Practical and theoretical implications are discussed.
Show less - Date Issued
- 2018
- Identifier
- CFE0007053, ucf:51989
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007053
- Title
- A laser radar employing linearly chirped pulses from a mode-locked laser for long range, unambiguous, sub-millimeter resolution ranging and velocimetry.
- Creator
-
Piracha, Mohammad Umar, ,, University of Central Florida
- Abstract / Description
-
Light detection and ranging (lidar) is used for various applications such as remote sensing, altimetry and imaging. In this talk, a linearly chirped pulse source is introduced that generates wavelength-swept pulses exhibiting ~6 nm optical bandwidth with (>) 20 km coherence length. The chirped pulses are used in an interferometric lidar setup to perform distance measurements with sub-millimeter resolution (using pulses that are a few meters long), at target distances (>) 10 km, with at least...
Show moreLight detection and ranging (lidar) is used for various applications such as remote sensing, altimetry and imaging. In this talk, a linearly chirped pulse source is introduced that generates wavelength-swept pulses exhibiting ~6 nm optical bandwidth with (>) 20 km coherence length. The chirped pulses are used in an interferometric lidar setup to perform distance measurements with sub-millimeter resolution (using pulses that are a few meters long), at target distances (>) 10 km, with at least 25 dB signal-to-noise ratio at the receiver. A pulse repetition rate of 20 MHz provides fast update rates, while chirped pulse amplification allows easy amplification of optical signals to high power levels that are required for long range operation. A pulse tagging scheme based on phase modulation is used to demonstrate unambiguous, long range measurements. In addition to this, simultaneous measurement of target range and Doppler velocity is performed using a target moving at a speed of over 330 km/h (205 mph) inside the laboratory. In addition to this, spectral phase modulation of the chirped pulses is demonstrated to compensate for the undesirable ripple in the group delay of the chirped pulses. Moreover, spectral amplitude modulation is used to generate pulses with Gaussian temporal intensity profiles and a two-fold increase in the lidar range resolution (284 um) is observed.
Show less - Date Issued
- 2012
- Identifier
- CFE0004423, ucf:49409
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004423
- Title
- Characterization of online archives of astronomical imaging vis-(&)#224;-vis serendipitous asteroids, and their astrometric properties.
- Creator
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Denis, Jean-Marc, Fernandez, Yanga, Britt, Daniel, Schelling, Patrick, University of Central Florida
- Abstract / Description
-
The identification of known asteroids on existing CCD pictures would allow us to obtain accurate astrometric and photometric asteroid properties. Some asteroids might have ambiguous orbital elements, thus their identification along with their exact positions on multiple picture frames could significantly improve their orbital elements. Furthermore, the possibility of identifying known asteroids on older pictures, sometimes preceding their discovery date, might allow the study of non...
Show moreThe identification of known asteroids on existing CCD pictures would allow us to obtain accurate astrometric and photometric asteroid properties. Some asteroids might have ambiguous orbital elements, thus their identification along with their exact positions on multiple picture frames could significantly improve their orbital elements. Furthermore, the possibility of identifying known asteroids on older pictures, sometimes preceding their discovery date, might allow the study of non-gravitational effects like the Yarkovsky effect.Identifying a potential Yarkovsky effect on asteroids is challenging because it is extremely weak. However, this effect cumulates with time, therefore, it is necessary to find astronomical pictures that are as old as possible. In addition, we need to collect high quality CCD pictures and use a methodology that would allow obtaining a statistically significant sample of asteroids. To accomplish this, we decided to use the online archive of the Subaru telescope at Mauna Kea Hawaii because it has a prime-focus camera with a very high resolution of 80 millions pixels very well suited to capture serendipitous asteroids. In addition, the Subaru online archive has pictures from the last 10 years.The methodology used in this thesis is to build a database that contains the orbital elements of all the known asteroids, allowing us to write a program that calculates the approximate position of all the asteroids at the date and time of each CCD picture we collect. To obtain a more precise position, the program also interfaces the JPL NASA Horizons on-line computation service. Every time an asteroid is found on a picture, Horizons sends its theoretical location back to the program. A later visual identification of this asteroid at this theoretical location on the picture triggers its input into our sample for further study. This method allowed us to visually confirm 508 distinct asteroids on 692 frames with an average diameter of 3.6 km. Finally, we use the theory (given in appendix A) to calculate the theoretical drift of these asteroids that we compare with the one we measured on the CCD pictures.
Show less - Date Issued
- 2012
- Identifier
- CFE0004299, ucf:49460
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004299
- Title
- Laser Spark Ignition of Counter-flow Diffusion Flames: Effects of diluents and diffusive-thermal properties.
- Creator
-
Sime Segura, Fidelio, Deng, Weiwei, Chen, Ruey-Hung, Kapat, Jayanta, University of Central Florida
- Abstract / Description
-
A pulsed Nd:YAG laser is used to study laser spark ignition of methane counter-flow diffusion flames with the use of helium and argon as diluents to achieve a wide range of variations in transport properties. The global strain rate and Damk(&)#246;hler number on successful ignition were investigated for the effects of Lewis number and transport properties, which are dependent on the diluent type and dilution level. A high-speed camera is used to record the ignition events and a software is...
Show moreA pulsed Nd:YAG laser is used to study laser spark ignition of methane counter-flow diffusion flames with the use of helium and argon as diluents to achieve a wide range of variations in transport properties. The global strain rate and Damk(&)#246;hler number on successful ignition were investigated for the effects of Lewis number and transport properties, which are dependent on the diluent type and dilution level. A high-speed camera is used to record the ignition events and a software is used for pre-ignition flow field and mixing calculations. It is found that the role of effective Lewis number on the critical global strain rate, beyond which ignition is not possible, is qualitatively similar that on the extinction strain rate. With the same level of dilution, the inert diluent with smaller Lewis number yields larger critical global strain rate. The critical Damk(&)#246;hler number below which no ignition is possible is found to be within approximately 20% for all the fuel-inert gas mixtures studied. When successful ignition takes place, the ignition time increases as the level of dilution of argon is increased. The ignition time decreases with increasing level of helium dilution due to decreases in thermal diffusion time, which causes rapid cooling of the flammable layer during the ignition process. However, the critical strain for ignition with helium dilution rapidly decreases as the dilution level is increased. The experimental results show that with the increase of strain rate the time to steady flame decreases, and that with the increase of dilution level time for the flame to become steady increases. For the same level of dilution, the time for steady flame is observed to be longer for He-diluted flames than for Ar-diluted flames due to its thermal diffusivity being larger than that of Ar.
Show less - Date Issued
- 2012
- Identifier
- CFE0004295, ucf:49467
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004295
- Title
- THE EFFECTS OF DELAY OF GRATIFICATION ON THE ACADEMIC ACHIEVEMENT, SUBSTANCE ABUSE, and VIOLENT BEHAVIOR OF MIDDLE-SCHOOL STUDENTS IN ALTERNATIVE LEARNING SETTINGS.
- Creator
-
Herndon, John, Gill, Michele, University of Central Florida
- Abstract / Description
-
This study examined the effects of delay of gratification on academic success, substance abuse, and violent behavior. The participants in this study were chosen from an alternative learning school comprised of middle school students in Florida. The hypothesis for this study is as follows: Delay of gratification is negatively related to substance abuse and violent behavior, and positively related to academic achievement. The analysis of the data was conducted on the primary predictor variable ...
Show moreThis study examined the effects of delay of gratification on academic success, substance abuse, and violent behavior. The participants in this study were chosen from an alternative learning school comprised of middle school students in Florida. The hypothesis for this study is as follows: Delay of gratification is negatively related to substance abuse and violent behavior, and positively related to academic achievement. The analysis of the data was conducted on the primary predictor variable (delay of gratification), alternate predictor variables (substance abuse and violent behavior) and the ultimate outcome variable (academic achievement) of this study. Initial statistical inquiry involved descriptive statistics (mean, standard deviation, kurtosis and skew) of the aforementioned variables, partial correlations (variable interrelationships), and the formulation of a multiple regression path analysis to investigate the particular paths individually within the proposed theoretical model (Wagner, 1993).
Show less - Date Issued
- 2011
- Identifier
- CFE0003756, ucf:48790
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003756
- Title
- Silicon photonic devices for optical delay lines and mid infrared applications.
- Creator
-
Khan, Saeed, Fathpour, Sasan, Likamwa, Patrick, Gong, Xun, Delfyett, Peter, Schoenfeld, Winston, University of Central Florida
- Abstract / Description
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Silicon photonics has been a rapidly growing subfield of integrated optics and optoelectronic in the last decade and is currently considered a mature technology. The main thrust behind the growth is its compatibility with the mature and low-cost microelectronic integrated circuits fabrication process. In recent years, several active and passive photonic devices and circuits have been demonstrated on silicon. Optical delay lines are among important silicon photonic devices, which are essential...
Show moreSilicon photonics has been a rapidly growing subfield of integrated optics and optoelectronic in the last decade and is currently considered a mature technology. The main thrust behind the growth is its compatibility with the mature and low-cost microelectronic integrated circuits fabrication process. In recent years, several active and passive photonic devices and circuits have been demonstrated on silicon. Optical delay lines are among important silicon photonic devices, which are essential for a variety of photonic system applications including optical beam-forming for controlling phased-array antennas, optical communication and networking systems and optical coherence tomography. In this thesis, several types of delay lines based on apodized grating waveguides are proposed and demonstrated. Simulation and experimental results suggest that these novel devices can provide high optical delay and tunability at very high bit rate. While most of silicon photonics research has focused in the near-infrared wavelengths, extending the operating wavelength range of the technology into in the 3(-)5 (&)#181;m, or the mid-wave infrared regime, is a more recent field of research. A key challenge has been that the standard silicon-on-insulator waveguides are not suitable for the mid-infrared, since the material loss of the buried oxide layer becomes substantially high. Here, the silicon-on-sapphire waveguide technology, which can extend silicon's operating wavelength range up to 4.4 (&)#181;m, is investigated. Furthermore, silicon-on-nitride waveguides, boasting a wide transparent range of 1.2(-)6.7 ?m, are demonstrated and characterized for the first time at both mid-infrared (3.39 ?m) and near-infrared (1.55 ?m) wavelengths.
Show less - Date Issued
- 2013
- Identifier
- CFE0005014, ucf:49996
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005014
- Title
- Ignition Studies of Oxy-Syngas/CO2 Mixtures Using Shock Tube for Cleaner Combustion Engines.
- Creator
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Barak, Samuel, Vasu Sumathi, Subith, Kapat, Jayanta, Ahmed, Kareem, University of Central Florida
- Abstract / Description
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In this study, syngas combustion was investigated behind reflected shock waves in order to gain insight into the behavior of ignition delay times and effects of the CO2 dilution. Pressure and light emissions time-histories measurements were taken at a 2 cm axial location away from the end wall. High-speed visualization of the experiments from the end wall was also conducted. Oxy-syngas mixtures that were tested in the shock tube were diluted with CO2 fractions ranging from 60% - 85% by volume...
Show moreIn this study, syngas combustion was investigated behind reflected shock waves in order to gain insight into the behavior of ignition delay times and effects of the CO2 dilution. Pressure and light emissions time-histories measurements were taken at a 2 cm axial location away from the end wall. High-speed visualization of the experiments from the end wall was also conducted. Oxy-syngas mixtures that were tested in the shock tube were diluted with CO2 fractions ranging from 60% - 85% by volume. A 10% fuel concentration was consistently used throughout the experiments. This study looked at the effects of changing the equivalence ratios (?), between 0.33, 0.5, and 1.0 as well as changing the fuel ratio (?), hydrogen to carbon monoxide, from 0.25, 1.0 and 4.0. The study was performed at 1.61-1.77 atm and a temperature range of 1006-1162K. The high-speed imaging was performed through a quartz end wall with a Phantom V710 camera operated at 67,065 frames per second. From the experiments, when increasing the equivalence ratio, it resulted in a longer ignition delay time. In addition, when increasing the fuel ratio, a lower ignition delay time was observed. These trends are generally expected with this combustion reaction system. The high-speed imaging showed non-homogeneous combustion in the system, however, most of the light emissions were outside the visible light range where the camera is designed for. The results were compared to predictions of two combustion chemical kinetic mechanisms: GRI v3.0 and AramcoMech v2.0 mechanisms. In general, both mechanisms did not accurately predict the experimental data. The results showed that current models are inaccurate in predicting CO2 diluted environments for syngas combustion.
Show less - Date Issued
- 2018
- Identifier
- CFE0006974, ucf:52909
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006974
- Title
- An Examination of Movement between Preschool and Kindergarten Classrooms for Young Children with Developmental Disabilities.
- Creator
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Ezekiel-Wilder, Faith, Dieker, Lisa, Little, Mary, Marino, Matthew, Levin, Judith, University of Central Florida
- Abstract / Description
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The researcher in this investigation describes the similarities and differences of movement in preschool and kindergarten classrooms for young children with developmental delay. Through the use of a mixed method research design, the researcher examined how movement is integrated throughout a school day and integrated into teacher-directed mathematics activities. This study used a multiple case study method that included observations of preschool (n= 3) and kindergarten (n= 3) classrooms to...
Show moreThe researcher in this investigation describes the similarities and differences of movement in preschool and kindergarten classrooms for young children with developmental delay. Through the use of a mixed method research design, the researcher examined how movement is integrated throughout a school day and integrated into teacher-directed mathematics activities. This study used a multiple case study method that included observations of preschool (n= 3) and kindergarten (n= 3) classrooms to determine similarities and differences in movement. In addition, a quantitative measure was embedded within the multiple case study design to compare movement of children with developmental delay. A thematic analysis resulted in themes connected to movement and teachers' perceptions in preschool and kindergarten. Preschool case themes included the use of videos with music for movement, literacy movement, physical transitions, fine motor activities, free play and fine motor manipulatives. Kindergarten case themes included: physical transitions, special areas, fine motor activities, and fine motor workbook activities. The researcher determined that while young children with disabilities in kindergarten classrooms exhibited higher levels of physical activity, as measured by steps taken, than young children with disabilities in preschool classrooms, preschool teachers consistently integrated a variety of movement activities at a higher rate. The results of this study exposed the need for a shared community interest of developing a scaffolding structure between preschool and kindergarten to ensure an effective transition between settings for children with DD.
Show less - Date Issued
- 2018
- Identifier
- CFE0007177, ucf:52257
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007177
- Title
- The Power of Quantum Walk: Insights, Implementation, and Applications.
- Creator
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Chiang, Chen-Fu, Wocjan, Pawel, Marinescu, Dan, Dechev, Damian, Mucciolo, Eduardo, University of Central Florida
- Abstract / Description
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In this thesis, I investigate quantum walks in quantum computing from threeaspects: the insights, the implementation, and the applications. Quantum walks are the quantum analogue of classical random walks. For the insights of quantum walks, I list and explain the required components for quantizing a classical random walk into a quantum walk. The components are, for instance, Markov chains, quantum phase estimation, and quantum spectrum theorem. I then demonstrate how the product of two...
Show moreIn this thesis, I investigate quantum walks in quantum computing from threeaspects: the insights, the implementation, and the applications. Quantum walks are the quantum analogue of classical random walks. For the insights of quantum walks, I list and explain the required components for quantizing a classical random walk into a quantum walk. The components are, for instance, Markov chains, quantum phase estimation, and quantum spectrum theorem. I then demonstrate how the product of two reflections in the walk operator provides a quadratic speed-up, in comparison to the classical counterpart. For the implementation of quantum walks, I show the construction of an efficient circuit for realizing one single step of the quantum walk operator. Furthermore, I devise a more succinct circuit to approximately implement quantum phase estimation with constant precision controlled phase shift operators. From an implementation perspective, efficient circuits are always desirable because the realization of a phase shift operator with high precision would be a costly task and a critical obstacle. For the applications of quantum walks, I apply the quantum walk technique along with other fundamental quantum techniques, such as phase estimation, to solve the partition function problem. However, there might be some scenario in which the speed-up of spectral gap is insignificant. In a situation like that that,I provide an amplitude amplification-based approach to prepare the thermal Gibbs state. Such an approach is useful when the spectral gap is extremely small. Finally, I further investigate and explore the effect of noise (perturbation)on the performance of quantum walks.
Show less - Date Issued
- 2011
- Identifier
- CFE0004094, ucf:49148
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004094
- 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
-
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
- Multi-transit echo suppression for passive wireless surface acoustic wave sensors using 3rd harmonic unidirectional transducers and Walsh-Hadamard-like reflectors.
- Creator
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Rodriguez Cordoves, Luis, Malocha, Donald, Weeks, Arthur, Abdolvand, Reza, Moharam, Jim, Youngquist, Robert, University of Central Florida
- Abstract / Description
-
A passive wireless surface acoustic wave sensor of a delay-line type is composed of an antenna, a transducer that converts the EM signal into a surface acoustic wave, and a set of acoustic reflectors that reflect the incoming signal back out through the antenna. A cavity forms between the transducer and the reflectors, trapping energy and causing multiple unwanted echoes. The work in this dissertation aims to reduce the unwanted echoes so that only the main transit signal is left(-)the signal...
Show moreA passive wireless surface acoustic wave sensor of a delay-line type is composed of an antenna, a transducer that converts the EM signal into a surface acoustic wave, and a set of acoustic reflectors that reflect the incoming signal back out through the antenna. A cavity forms between the transducer and the reflectors, trapping energy and causing multiple unwanted echoes. The work in this dissertation aims to reduce the unwanted echoes so that only the main transit signal is left(-)the signal of interest with sensor information.The contributions of this dissertation include reflective delay-line device response in the form of an infinite impulse response (IIR) filter. This may be used in the future to subtract out unwanted echoes via post-processing. However, this dissertation will use a physical approach to echo suppression by using a unidirectional transducer. Thus a unidirectional transducer is used and also optimized for 3rd harmonic operation. Both the directionality and the coupling of the 3rd harmonic optimized SPUDT are improved over a standard electrode width controlled (EWC) SPUDT. New type of reflectors for the reflective delay-line device are also presented. These use BPSK type coding, similar to that of the Walsh-Hadamard codes. Two types are presented, variable reflectivity and variable chip-lengths. The COM model is used to simulate devices and compare the predicted echo suppression level to that of fabricated devices. Finally, a device is mounted on a tunable antenna and the echo is suppressed on a wireless operating device.
Show less - Date Issued
- 2017
- Identifier
- CFE0006912, ucf:51697
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006912
