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(1 - 7 of 7)
- Title
- VARIATIONAL EMBEDDED SOLITONS, AND TRAVELING WAVETRAINS GENERATED BY GENERALIZED HOPF BIFURCATIONS, IN SOME NLPDE SYSTEMS.
- Creator
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Smith, Todd, Choudhury, Roy, University of Central Florida
- Abstract / Description
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In this Ph.D. thesis, we study regular and embedded solitons and generalized and degenerate Hopf bifurcations. These two areas of work are seperate and independent from each other. First, variational methods are employed to generate families of both regular and embedded solitary wave solutions for a generalized Pochhammer PDE and a generalized microstructure PDE that are currently of great interest. The technique for obtaining the embedded solitons incorporates several recent generalizations...
Show moreIn this Ph.D. thesis, we study regular and embedded solitons and generalized and degenerate Hopf bifurcations. These two areas of work are seperate and independent from each other. First, variational methods are employed to generate families of both regular and embedded solitary wave solutions for a generalized Pochhammer PDE and a generalized microstructure PDE that are currently of great interest. The technique for obtaining the embedded solitons incorporates several recent generalizations of the usual variational technique and is thus topical in itself. One unusual feature of the solitary waves derived here is that we are able to obtain them in analytical form (within the family of the trial functions). Thus, the residual is calculated, showing the accuracy of the resulting solitary waves. Given the importance of solitary wave solutions in wave dynamics and information propagation in nonlinear PDEs, as well as the fact that only the parameter regimes for the existence of solitary waves had previously been analyzed for the microstructure PDE considered here, the results obtained here are both new and timely. Second, we consider generalized and degenerate Hopf bifurcations in three different models: i. a predator-prey model with general predator death rate and prey birth rate terms, ii. a laser-diode system, and iii. traveling-wave solutions of twospecies predator-prey/reaction-diusion equations with arbitrary nonlinear/reaction terms. For speci c choices of the nonlinear terms, the quasi-periodic orbit in the post-bifurcation regime is constructed for each system using the method of multiple scales, and its stability is analyzed via the corresponding normal form obtained by reducing the system down to the center manifold. The resulting predictions for the post-bifurcation dynamics provide an organizing framework for the variety of possible behaviors. These predictions are veri ed and supplemented by numerical simulations, including the computation of power spectra, autocorrelation functions, and fractal dimensions as appropriate for the periodic and quasiperiodic attractors, attractors at in nity, as well as bounded chaotic attractors obtained in various cases. The dynamics obtained in the three systems is contrasted and explained on the basis of the bifurcations occurring in each. For instance, while the two predator-prey models yield a variety of behaviors in the post-bifurcation regime, the laser-diode evinces extremely stable quasiperiodic solutions over a wide range of parameters, which is very desirable for robust operation of the system in oscillator mode.
Show less - Date Issued
- 2011
- Identifier
- CFE0003634, ucf:48887
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003634
- Title
- MULTIPLE ASPECTS OF NATURAL KILLER CELL EXPANSION IN RELEVANCE TO IMMUNOTHERAPY FOR HEMATOLOGIC MALIGNANCIES.
- Creator
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Colosimo, Dominic, Borgon, Robert, University of Central Florida
- Abstract / Description
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Natural Killer (NK) cells are a subset of lymphocytes that regulate adaptive immune responses and utilize "missing self" recognition to activate anti-tumor and anti-viral cytotoxicity. Clinical research, as well as murine and ex vivo models, have shown that a variety of NK cell applications have proven useful as immunotherapeutic treatments for patients with hematologic malignancies. However, the selective expansion of NK cells to yield relevant amounts of these lymphocytes has been a major...
Show moreNatural Killer (NK) cells are a subset of lymphocytes that regulate adaptive immune responses and utilize "missing self" recognition to activate anti-tumor and anti-viral cytotoxicity. Clinical research, as well as murine and ex vivo models, have shown that a variety of NK cell applications have proven useful as immunotherapeutic treatments for patients with hematologic malignancies. However, the selective expansion of NK cells to yield relevant amounts of these lymphocytes has been a major hurdle in the development of methods for clinical therapeutic use. Here, we demonstrate a novel ex vivo expansion method utilizing k562 leukemic cell lines and soluble cytokines as well as a novel method utilizing isolated plasma membranes of genetically engineered tumor cell lines that could be of relevance to in vivo NK cell expansion. Also, the ligand expression by canonical feeder cell lines used for NK cell expansion and our isolated plasma membranes were compared via ligand quantification by western blot quantification of 4-1BB ligand. In an adjunct study, we sought to better characterize these expansion environments by investigating the glucose metabolism of NK cells using fluorescent glucose analog 2-(N-(7-Nitrobenz-2-oxa-1, 3-diazol-4-yl)Amino)-2-Deoxyglucose (2-NBDG) and the glycolysis inhibitor 2-Deoxy-D-Glucose (2-DG).
Show less - Date Issued
- 2012
- Identifier
- CFH0004252, ucf:44917
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004252
- Title
- PRESSURE LOSSES EXPERIENCED BY LIQUID FLOW THROUGH PDMS MICROCHANNELS WITH ABRUPT AREA CHANGES.
- Creator
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Wehking, Jonathan, Chew, Larry, University of Central Florida
- Abstract / Description
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Given the surmounting disagreement amongst researchers in the area of liquid flow behavior at the microscale for the past thirty years, this work presents a fundamental approach to analyzing the pressure losses experienced by the laminar flow of water (Re = 7 to Re = 130) through both rectangular straight duct microchannels (of widths ranging from 50 to 130 micrometers), and microchannels with sudden expansions and contractions (with area ratios ranging from 0.4 to 1.0) all with a constant...
Show moreGiven the surmounting disagreement amongst researchers in the area of liquid flow behavior at the microscale for the past thirty years, this work presents a fundamental approach to analyzing the pressure losses experienced by the laminar flow of water (Re = 7 to Re = 130) through both rectangular straight duct microchannels (of widths ranging from 50 to 130 micrometers), and microchannels with sudden expansions and contractions (with area ratios ranging from 0.4 to 1.0) all with a constant depth of 104 micrometers. The simplified Bernoulli equations for uniform, steady, incompressible, internal duct flow were used to compare flow through these microchannels to macroscale theory predictions for pressure drop. One major advantage of the channel design (and subsequent experimental set-up) was that pressure measurements could be taken locally, directly before and after the test section of interest, instead of globally which requires extensive corrections to the pressure measurements before an accurate result can be obtained. Bernoulli's equation adjusted for major head loses (using Darcy friction factors) and minor head losses (using appropriate K values) was found to predict the flow behavior within the calculated theoretical uncertainty (~12%) for all 150+ microchannels tested, except for sizes that pushed the aspect ratio limits of the manufacturing process capabilities (microchannels fabricated via soft lithography using PDMS). The analysis produced conclusive evidence that liquid flow through microchannels at these relative channel sizes and Reynolds numbers follow macroscale predictions without experiencing any of the reported anomalies expressed in other microfluidics research. This work also perfected the delicate technique required to pierce through the PDMS material and into the microchannel inlets, exit and pressure ports without damaging the microchannel. Finally, two verified explanations for why prior researchers have obtained poor agreement between macroscale theory predictions and tests at the microscale were due to the presence of bubbles in the microchannel test section (producing higher than expected pressure drops), and the occurrence of localized separation between the PDMS slabs and thus, the microchannel itself (producing lower than expected pressure drops).
Show less - Date Issued
- 2008
- Identifier
- CFE0002289, ucf:47865
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002289
- Title
- Dog Ownership as a Catalyst of Conflict and Relationship Maintenance in Romantic Relationships.
- Creator
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Elrick, Ashley, Weger, Harry, Miller, Ann, Hastings, Sally, University of Central Florida
- Abstract / Description
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Pets are a common aspect of life for many Americans. In 2012, 36.5% of American household owned dogs and 30.4% owned cats (American Veterinary Medical Foundation, 2012). The purpose on this study was to explore the influence of dog ownership on romantic relationships. Specifically, this thesis investigates how dog ownership acts as a catalyst of relational maintenance and conflict behavior in interactions about the couple's dog. No prior research has been conducted on the role dogs' play in...
Show morePets are a common aspect of life for many Americans. In 2012, 36.5% of American household owned dogs and 30.4% owned cats (American Veterinary Medical Foundation, 2012). The purpose on this study was to explore the influence of dog ownership on romantic relationships. Specifically, this thesis investigates how dog ownership acts as a catalyst of relational maintenance and conflict behavior in interactions about the couple's dog. No prior research has been conducted on the role dogs' play in enacting relational maintenance or conflict in romantic relationships, so it is unclear if there is an influence to the these behaviors. This study asks how dog ownership might act as a centripetal force pulling the relationship together (e.g. relational maintenance) and/or as a centrifugal force pushing the partners apart (e.g. conflict). A total of 379 participants were recruited through social media to complete a short online survey. The survey asked questions on the romantic relationship, dog ownership, conflict regarding the dog, relational maintenance activities regarding the dog, and demographics. The majority of participants reported engaging in 8 of the 24 relational maintenance activities (")often(") or (")always(") and 3 of the 30 conflict topics occurred at least one or more times. Satisfaction with the romantic relationship associated positively with partial weak and negligible correlations to the relational maintenance activities and one negligible association with a conflict topic. A thematic analysis provides details on the short answers participants provided. The results shows that dogs do provide couples opportunities for relational maintenance but also are the source of conflict. This research is the start to understanding the role of dog ownership within romantic relationship. While each couple and dog may produce different influences on the relationship, this study is the start for the investigation and provides guidance for future research.
Show less - Date Issued
- 2014
- Identifier
- CFE0005328, ucf:50533
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005328
- Title
- Stochastic Optimization for Integrated Energy System with Reliability Improvement Using Decomposition Algorithm.
- Creator
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Huang, Yuping, Zheng, Qipeng, Xanthopoulos, Petros, Pazour, Jennifer, Liu, Andrew, University of Central Florida
- Abstract / Description
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As energy demands increase and energy resources change, the traditional energy system has beenupgraded and reconstructed for human society development and sustainability. Considerable studies have been conducted in energy expansion planning and electricity generation operations bymainly considering the integration of traditional fossil fuel generation with renewable generation.Because the energy market is full of uncertainty, we realize that these uncertainties have continuously challenged...
Show moreAs energy demands increase and energy resources change, the traditional energy system has beenupgraded and reconstructed for human society development and sustainability. Considerable studies have been conducted in energy expansion planning and electricity generation operations bymainly considering the integration of traditional fossil fuel generation with renewable generation.Because the energy market is full of uncertainty, we realize that these uncertainties have continuously challenged market design and operations, even a national energy policy. In fact, only a few considerations were given to the optimization of energy expansion and generation taking into account the variability and uncertainty of energy supply and demand in energy markets. This usually causes an energy system unreliable to cope with unexpected changes, such as a surge in fuel price, a sudden drop of demand, or a large renewable supply fluctuation. Thus, for an overall energy system, optimizing a long-term expansion planning and market operation in a stochastic environment are crucial to improve the system's reliability and robustness.As little consideration was paid to imposing risk measure on the power management system, this dissertation discusses applying risk-constrained stochastic programming to improve the efficiency,reliability and economics of energy expansion and electric power generation, respectively. Considering the supply-demand uncertainties affecting the energy system stability, three different optimization strategies are proposed to enhance the overall reliability and sustainability of an energy system. The first strategy is to optimize the regional energy expansion planning which focuses on capacity expansion of natural gas system, power generation system and renewable energy system, in addition to transmission network. With strong support of NG and electric facilities, the second strategy provides an optimal day-ahead scheduling for electric power generation system incorporating with non-generation resources, i.e. demand response and energy storage. Because of risk aversion, this generation scheduling enables a power system qualified with higher reliability and promotes non-generation resources in smart grid. To take advantage of power generation sources, the third strategy strengthens the change of the traditional energy reserve requirements to risk constraints but ensuring the same level of systems reliability In this way we can maximize the use of existing resources to accommodate internal or/and external changes in a power system.All problems are formulated by stochastic mixed integer programming, particularly consideringthe uncertainties from fuel price, renewable energy output and electricity demand over time. Taking the benefit of models structure, new decomposition strategies are proposed to decompose the stochastic unit commitment problems which are then solved by an enhanced Benders Decomposition algorithm. Compared to the classic Benders Decomposition, this proposed solution approachis able to increase convergence speed and thus reduce 25% of computation times on the same cases.
Show less - Date Issued
- 2014
- Identifier
- CFE0005506, ucf:50339
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005506
- Title
- OPTICAL AND PHYSICAL PROPERTIES OF CERAMIC CRYSTAL LASER MATERIALS.
- Creator
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Simmons, Jed, Bass, Michael, University of Central Florida
- Abstract / Description
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Historically ceramic crystal laser material has had disadvantages compared to single crystal laser material. However, progress has been made in the last decade and a half to overcome the disadvantages associated with ceramic crystal. Today, because of the promise of ceramic crystal as a high power laser material, investigation into its properties, both physical and optical, is warranted and important. Thermal expansion was measured in this thesis for Nd:YAG (yttrium aluminum garnet) ceramic...
Show moreHistorically ceramic crystal laser material has had disadvantages compared to single crystal laser material. However, progress has been made in the last decade and a half to overcome the disadvantages associated with ceramic crystal. Today, because of the promise of ceramic crystal as a high power laser material, investigation into its properties, both physical and optical, is warranted and important. Thermal expansion was measured in this thesis for Nd:YAG (yttrium aluminum garnet) ceramic crystal using an interferometric method. The interferometer employed a spatially filtered HeNe at 633 nm wavelength. Thermal expansion coefficients measured for the ceramic crystal samples were near the reported values for single crystal Nd:YAG. With a similar experimental setup as that for the thermal expansion measurements, dn/dT for ceramic crystal Nd:YAG was measured and found to be slightly higher than the reported value for single crystal. Depolarization loss due to thermal gradient induced stresses can limit laser performance. As a result this phenomenon was modeled for ceramic crystal materials and compared to single crystals for slab and rod shaped gain media. This was accomplished using COMSOL Multiphysics, and MATLAB. Results indicate a dependence of the depolarization loss on the grain size where the loss decreases with decreased grain size even to the point where lower loss may be expected in ceramic crystals than in single crystal samples when the grain sizes in the ceramic crystal are sufficiently small. Deformation-induced thermal lensing was modeled for a single crystal slab and its relevance to ceramic crystal is discussed. Data indicates the most notable cause of deformation-induced thermal lensing is a consequence of the deformation of the top and bottom surfaces. Also, the strength of the lensing along the thickness is greater than the width and greater than that due to other causes of lensing along the thickness of the slab. Emission spectra, absorption spectra, and fluorescence lifetime were measured for Nd:YAG ceramic crystal and Yb:Lu2O3 ceramic crystal. No apparent inhomogeneous broadening appears to exist in the Nd:YAG ceramic at low concentrations. Concentration and temperature dependence effects on emission spectra were measured and are presented. Laser action in a thin disk of Yb:Y2O3 ceramic crystal was achieved. Pumping was accomplished with a fiber coupled diode laser stack at 938 nm. A slope efficiency of 34% was achieved with maximum output energy of 28.8 mJ/pulse.
Show less - Date Issued
- 2007
- Identifier
- CFE0001764, ucf:47273
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001764
- Title
- FROM PRE-ISLAM TO MANDATE STATES: EXAMINING CULTURAL IMPERIALISM AND CULTURAL BLEED IN THE LEVANT.
- Creator
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Willman, Gabriel, Özoğlu, Hakan, University of Central Florida
- Abstract / Description
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To a large degree, historical analyses of the Levantine region tend to focus primarily upon martial interaction and state formation. However, perhaps of equitable impact is the chronology of those interactions which are cultural in nature. The long-term formative effect of cultural imperialism and cultural bleed can easily be as influential as the direct alterations imposed by martial invasion. While this study does not attempt to establish comparative causal weight or catalytic impact...
Show moreTo a large degree, historical analyses of the Levantine region tend to focus primarily upon martial interaction and state formation. However, perhaps of equitable impact is the chronology of those interactions which are cultural in nature. The long-term formative effect of cultural imperialism and cultural bleed can easily be as influential as the direct alterations imposed by martial invasion. While this study does not attempt to establish comparative causal weight or catalytic impact between these types of interactions, it does contend that the cultural evolution of the Levant has been significantly influenced by external interaction for a period of time extending beyond the Levantine Islamic Expansion. This study presents a chronological examination of the region from the pre-Expansion Period through the Mandate Period, focused upon relevant cultural structures. Specifically, emphasis is placed upon religious, ethnic, and nationalistic identity development, sociolinguistic shifts, and institutional changes within the societal structure. The primary conclusion of this study is that significant evidence exists to support a long-term historical narrative of externally influenced Levantine cultural evolution, inclusive of both adaptive and reactive interactions.
Show less - Date Issued
- 2013
- Identifier
- CFH0004490, ucf:45075
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004490
