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- Title
- Nonlinear integrated photonics on silicon and gallium arsenide substrates.
- Creator
-
Ma, Jichi, Fathpour, Sasan, Hagan, David, Li, Guifang, Peale, Robert, University of Central Florida
- Abstract / Description
-
Silicon photonics is nowadays a mature technology and is on the verge of becoming a blossoming industry. Silicon photonics has also been pursued as a platform for integrated nonlinear optics based on Raman and Kerr effects. In recent years, more futuristic directions have been pursued by various groups. For instance, the realm of silicon photonics has been expanded beyond the well-established near-infrared wavelengths and into the mid-infrared (3 (-) 5 (&)#181;m). In this wavelength range,...
Show moreSilicon photonics is nowadays a mature technology and is on the verge of becoming a blossoming industry. Silicon photonics has also been pursued as a platform for integrated nonlinear optics based on Raman and Kerr effects. In recent years, more futuristic directions have been pursued by various groups. For instance, the realm of silicon photonics has been expanded beyond the well-established near-infrared wavelengths and into the mid-infrared (3 (-) 5 (&)#181;m). In this wavelength range, the omnipresent hurdle of nonlinear silicon photonics in the telecommunication band, i.e., nonlinear losses due to two-photon absorption, is inherently nonexistent. With the lack of efficient light-emission capability and second-order optical nonlinearity in silicon, heterogeneous integration with other material systems has been another direction pursued. Finally, several approaches have been proposed and demonstrated to address the energy efficiency of silicon photonic devices in the near-infrared wavelength range. In this dissertation, theoretical and experimental works are conducted to extend applications of integrated photonics into mid-infrared wavelengths based on silicon, demonstrate heterogeneous integration of tantalum pentoxide and lithium niobate photonics on silicon substrates, and study two-photon photovoltaic effect in gallium arsenide and plasmonic-enhanced structures.Specifically, performance and noise properties of nonlinear silicon photonic devices, such as Raman lasers and optical parametric amplifiers, based on novel and reliable waveguide technologies are studied. Both near-infrared and mid-infrared nonlinear silicon devices have been studied for comparison. Novel tantalum-pentoxide- and lithium-niobate-on-silicon platforms are developed for compact microring resonators and Mach-Zehnder modulators. Third- and second-harmonic generations are theoretical studied based on these two platforms, respectively. Also, the two-photon photovoltaic effect is studied in gallium arsenide waveguides for the first time. The effect, which was first demonstrated in silicon, is the nonlinear equivalent of the photovoltaic effect of solar cells and offers a viable solution for achieving energy-efficient photonic devices. The measured power efficiency achieved in gallium arsenide is higher than that in silicon and even higher efficiency is theoretically predicted with optimized designs. Finally, plasmonic-enhanced photovoltaic power converters, based on the two-photon photovoltaic effect in silicon using subwavelength apertures in metallic films, are proposed and theoretically studied.
Show less - Date Issued
- 2014
- Identifier
- CFE0005373, ucf:50441
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005373
- Title
- Use of Integrated Training Environments to Sustain Army Warfighting Proficiency in an Era of Constrained Resources: Understanding What's Required to Win the First Battle of the Next Conflict.
- Creator
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Lerz, Edward, Proctor, Michael, Nickerson, David, Goodwin, Gregory, University of Central Florida
- Abstract / Description
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This research investigates the current state and ability of homestation training infrastructure (TADSS, networks, and facilities) and framework for training (scenarios, databases, and training support packages) to support a Live Virtual Constructive (-) Integrating Architecture (LVC-IA) delivered Integrated Training Environment (ITE). As combat operations in Central and Southwest Asia come to a close the Army is faced with extreme post-conflict budget cuts and force reductions. Continued...
Show moreThis research investigates the current state and ability of homestation training infrastructure (TADSS, networks, and facilities) and framework for training (scenarios, databases, and training support packages) to support a Live Virtual Constructive (-) Integrating Architecture (LVC-IA) delivered Integrated Training Environment (ITE). As combat operations in Central and Southwest Asia come to a close the Army is faced with extreme post-conflict budget cuts and force reductions. Continued evolution of Army training methodology is required to overcome limited resources and maintain force readiness in the anticipated (")era of persistent conflict("). A LVC-IA delivered ITE promises to be the next step in the evolution of training. Interoperation of live, virtual, and constructive simulations in a persistent and consistent manner can collectively train brigade and below units on combined arms tasks in a resource constrained homestation environment. However, LVC-IA cannot act alone in establishing the ITE. Prior to the fielding of LVC-IA, local installations must already possess a training infrastructure that optimizes training resources as well as a framework for training that meets Operational Adaptability training requirements. To measure the perceived state and ability of homestation training infrastructure and framework for training to support a LVC-IA delivered ITE, a survey was conducted of homestation training community members at the 18 Army installations scheduled for LVC-IA fielding. Additionally, perceptions regarding the role of LVC-IA in establishing the ITE and emerging resources, useful in the development of local framework for training were sought. Findings, conclusions, limitations, lessons learned, and recommendations for future research are presented.?
Show less - Date Issued
- 2013
- Identifier
- CFE0005104, ucf:50755
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005104
- Title
- THE EFFECTS OF EMERGING TECHNOLOGY ON HEALTHCARE AND THE DIFFICULTIES OF INTEGRATION.
- Creator
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Pavlish-Carpenter, Skyler J, D'Amato-Kubiet, Leslee, University of Central Florida
- Abstract / Description
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Background: Disruptive technology describes technology that is significantly more advanced than previous iterations, such as: 3D printing, genetic manipulation, stem cell research, innovative surgical procedures, and computer-based charting software. These technologies often require extensive overhauls to implement into older systems and must overcome many difficult financial and societal complications before they can be widely used. In a field like healthcare that makes frequent advancements...
Show moreBackground: Disruptive technology describes technology that is significantly more advanced than previous iterations, such as: 3D printing, genetic manipulation, stem cell research, innovative surgical procedures, and computer-based charting software. These technologies often require extensive overhauls to implement into older systems and must overcome many difficult financial and societal complications before they can be widely used. In a field like healthcare that makes frequent advancements, these difficulties can mean that the technology will not be utilized to its full potential or implemented at all. Objective: To determine the inhibiting factors that prevent disruptive technology from being implemented in conventional healthcare. Methods: Peer reviewed articles were gathered from Cumulative Index to Nursing and Allied Health Literature (CINAHL), Educational Resources Information Center (ERIC), Elton B. Stephens Co. Host (Ebsco Host), Medical Literature On-line (Medline), and Psychological Information Database (PsychINFO). Articles were included if written in English and focusing on technology that was or is difficult to implement. Results: Research suggests that the primary reason disruptive technology is not implemented sooner is the cost versus benefit ratio. Those technologies with extremely high benefits that greatly improve efficiency, safety, or expense are integrated relatively quickly, especially if their cost is reasonable. Secondary reasons for difficulty with integration include ethical dilemmas, extreme complexity, technical limitations, maintenance, security, and fallibility. Conclusion: Research indicates that a decrease in production cost and selling price along with removing any issues that may depreciate the technology will provide better incentives for healthcare systems to integrate disruptive technologies on a wider scale.
Show less - Date Issued
- 2018
- Identifier
- CFH2000374, ucf:45799
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000374
- Title
- HOT CARRIER EFFECT ON LDMOS TRANSISTORS.
- Creator
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Jiang, Liangjun, Yuan, Jiann S., University of Central Florida
- Abstract / Description
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One of the main problems encountered when scaling down is the hot carrier induced degradation of MOSFETs. This problem has been studied intensively during the past decade, under both static and dynamic stress conditions. In this period it has evolved from a more or less academic research topic to one of the most stringent constraints guaranteeing the lifetime of sub-micron devices. New drain engineering technique leads to the extensive usage of lateral doped drain structures. In these devices...
Show moreOne of the main problems encountered when scaling down is the hot carrier induced degradation of MOSFETs. This problem has been studied intensively during the past decade, under both static and dynamic stress conditions. In this period it has evolved from a more or less academic research topic to one of the most stringent constraints guaranteeing the lifetime of sub-micron devices. New drain engineering technique leads to the extensive usage of lateral doped drain structures. In these devices the peak of the lateral field is lowered by reducing the doping concentration near the drain and by providing a smooth junction transition instead of an abrupt one. Therefore, the amount of hot carrier generation for a given supply voltage and the influence of a certain physical damage on the electrical characteristics is decreased dramatically. A complete understanding of the hot carrier degradation problem in sub-micron 0.25um LD MOSFETs is presented in this work. First we discuss the degradation mechanisms observed under, for circuit operation, somewhat artificial but well-controlled uniform-substrate hot electron and substrate hot-hole injection conditions. Then the more realistic case of static channel hot carrier degradation is treated, and some important process-related effects are illustrated, followed by the behavior under the most relevant case for real operation, namely dynamic degradation. An Accurate and practical parameter extraction is used to obtain the LD MOSFETs model parameters, with the experiment verification. Good agreement between the model simulation and experiment is achieved. The gate charge transfer performance is examined to demonstrate the hot carrier effect. Furthermore, In order to understand the dynamic stress on the LD MOSFET and its effect on RF circuit, the hot-carrier injection experiment in which dynamic stress with different duty cycle applied to a LD MOS transistor is presented. A Class-C power amplifier is used to as an example to demonstrate the effect of dynamic stress on RF circuit performance. Finally, the strategy for improving hot carrier reliability and a forecast of the hot carrier reliability problem for nano-technologies are discussed. The main contribution of this work is, it systemically research the hot carrier reliability issue on the sub-micron lateral doped drain MOSFETs, which is induced by static and dynamic voltage stress; The stress condition mimics the typical application scenarios of LD MOSFET. Model parameters extraction technique is introduced with the aid of the current device modeling tools, the performance degradation model can be easily implement into the existing computer-aided tools. Therefore, circuit performance degradation can be accurately estimated in the design stage. CMOS technologies are constantly scaled down. The production on 65 nm is on the market. With the reduction in geometries, the devices become more vulnerable to hot carrier injection (HCI). HCI reliability is a must for designs implemented with new processes. Reliability simulation needs to be implemented in PDK libraries located on the modeling stage. The use of professional tools is a prerequisite to develop accurate device models, from DC to GHz, including noise modeling and nonlinear HF effects, within a reasonable time. Designers need to learn to design for reliability and they should be educated on additional reliability analyses. The value is the reduction of failure and redesign costs.
Show less - Date Issued
- 2007
- Identifier
- CFE0001551, ucf:47148
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001551
- Title
- FLORIDA FIRST YEAR TEACHERS' PERCEPTIONS OF PREPAREDNESS TO MEET NATIONAL EDUCATIONAL TECHNOLOGY STANDARDS FOR TEACHERS (NETS-T).
- Creator
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Bedenbaugh, Larry, Taylor, Rosemarye, University of Central Florida
- Abstract / Description
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The purpose of this study was to determine if first year teachers in Florida perceived they were adequately prepared by their preservice education programs to meet the National Educational Technology Standards for Teachers (NETS-T). The study was designed to gather data about first year teacher perceptions of personal technology proficiency and self-reported technology integration practices. The data were measured using the First Year Teacher Perceptions Related to Preparedness to Meet...
Show moreThe purpose of this study was to determine if first year teachers in Florida perceived they were adequately prepared by their preservice education programs to meet the National Educational Technology Standards for Teachers (NETS-T). The study was designed to gather data about first year teacher perceptions of personal technology proficiency and self-reported technology integration practices. The data were measured using the First Year Teacher Perceptions Related to Preparedness to Meet National Educational Technology Standards for Teachers (NETS-T) survey instrument. The sample (N=257) for this study was drawn from the population of Florida first year PreK-12 public classroom teachers from the 20052006 school year who were still teaching during the 2006-2007 school year. Demographic variables, perceptions of personal technology skills, and self-reported technology integration practices were collected on the sample. Descriptive and comparative statistics were used to identify relationships between the variables. It was concluded that first year teachers in Florida who held a professional teaching certificate or graduated from a Florida public university's teacher education program perceived they were better prepared to meet national educational technology standards than first year teachers in Florida who did not. It was also determined that there was a statistically significant relationship between first year teacher perceptions for preparedness for technology integration and their perceived personal technology skills, as well as between self-reported technology integration practices of first year teachers and their perceptions of their ability to integrate technology. Two additional findings came to light during the study. The majority of first year teachers in Florida did not take the traditional university teacher preparation program as their path to certification. Additionally, the vast majority of first year teachers in Florida gave credit to independent learning in increasing their own personal technology skills.
Show less - Date Issued
- 2007
- Identifier
- CFE0001727, ucf:47320
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001727
- Title
- REAL-TIME TREE SIMULATION USING VERLET INTEGRATION.
- Creator
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Manavi, Bobak, Kincaid, J. Peter, University of Central Florida
- Abstract / Description
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One of the most important challenges in real-time simulation of large trees and vegetation is the vast number of calculations required to simulate the interactions between all the branches in the tree when external forces are applied to it. This paper will propose the use of algorithms employed by applications like cloth and soft body simulations, where objects can be represented by a finite system of particles connected via spring-like constraints, for the structural representation and...
Show moreOne of the most important challenges in real-time simulation of large trees and vegetation is the vast number of calculations required to simulate the interactions between all the branches in the tree when external forces are applied to it. This paper will propose the use of algorithms employed by applications like cloth and soft body simulations, where objects can be represented by a finite system of particles connected via spring-like constraints, for the structural representation and manipulation of trees in real-time. We will then derive and show the use of Verlet integration and the constraint configuration used for simulating trees while constructing the necessary data structures that encapsulate the procedural creation of these objects. Furthermore, we will utilize this system to simulate branch breakage due to accumulated external and internal pressure.
Show less - Date Issued
- 2007
- Identifier
- CFE0001802, ucf:47381
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001802
- Title
- STABILITY AND PRESERVATION PROPERTIES OF MULTISYMPLECTIC INTEGRATORS.
- Creator
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Wlodarczyk, Tomasz, Schober, Constance, University of Central Florida
- Abstract / Description
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This dissertation presents results of the study on symplectic and multisymplectic numerical methods for solving linear and nonlinear Hamiltonian wave equations. The emphasis is put on the second order space and time discretizations of the linear wave, the Klein-Gordon and the sine-Gordon equations. For those equations we develop two multisymplectic (MS) integrators and compare their performance to other popular symplectic and non-symplectic numerical methods. Tools used in the linear analysis...
Show moreThis dissertation presents results of the study on symplectic and multisymplectic numerical methods for solving linear and nonlinear Hamiltonian wave equations. The emphasis is put on the second order space and time discretizations of the linear wave, the Klein-Gordon and the sine-Gordon equations. For those equations we develop two multisymplectic (MS) integrators and compare their performance to other popular symplectic and non-symplectic numerical methods. Tools used in the linear analysis are related to the Fourier transform and consist of the dispersion relationship and the power spectrum of the numerical solution. Nonlinear analysis, in turn, is closely connected to the temporal evolution of the total energy (Hamiltonian) and can be viewed from the topological perspective as preservation of the phase space structures. Using both linear and nonlinear diagnostics we find qualitative differences between MS and non-MS methods. The first difference can be noted in simulations of the linear wave equation solved for broad spectrum Gaussian initial data. Initial wave profiles of this type immediately split into an oscillatory wave-train with the high modes traveling faster (MS schemes), or slower (non-MS methods), than the analytic group velocity. This result is confirmed by an analysis of the dispersion relationship, which also indicates improved qualitative agreement of the dispersive curves for MS methods over non-MS ones. Moreover, observations of the convergence patterns in the wave profile obtained for the sine-Gordon equation for the initial data corresponding to the double-pole soliton and the temporal evolution of the Hamiltonian functional computed for solutions obtained from different discretizations suggest a change of the geometry of the phase space. Finally, we present some theoretical considerations concerning wave action. Lagrangian formulation of linear partial differential equations (PDEs) with slowly varying solutions is capable of linking the wave action conservation law with the dispersion relationship thus suggesting the possibility to extend this connection to multisymplectic PDEs.
Show less - Date Issued
- 2007
- Identifier
- CFE0001817, ucf:47344
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001817
- Title
- MAGNETICS DESIGN FOR HIGH CURRENT LOW VOLTAGE DC/DC CONVERTER.
- Creator
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zhou, hua, Wu, Thomas Xinzhang, University of Central Florida
- Abstract / Description
-
With the increasing demand for small and cost efficient DC/DC converters, the power converters are expected to operate with high efficiency. Magnetics components design is one of the biggest challenges in achieving the higher power density and higher efficiency due to the significant portion of magnetics components volume in the whole power system. At the same time, most of the experimental phenomena are related to the magnetics components. So, good magnetics components design is one of the...
Show moreWith the increasing demand for small and cost efficient DC/DC converters, the power converters are expected to operate with high efficiency. Magnetics components design is one of the biggest challenges in achieving the higher power density and higher efficiency due to the significant portion of magnetics components volume in the whole power system. At the same time, most of the experimental phenomena are related to the magnetics components. So, good magnetics components design is one of the key issues to implement low voltage high current DC/DC converter. Planar technology has many advantages. It has low profile construction, low leakage inductance and inter-winding capacitance, excellent repeatability of parasitic properties, cost efficiency, great reliability, and excellent thermal characteristics. On the other side, however, planar technology also has some disadvantages. Although it improves thermal performance, the planar format increases footprint area. The fact that windings can be placed closer in planar technology to reduce leakage inductance also often has an unwanted effect of increasing parasitic capacitances. In this dissertation, the planar magnetics designs for high current low voltage applications are thoroughly investigated and one CAD design methodology based on FEA numerical analysis is proposed. Because the frequency dependant parasitic parameters of magnetics components are included in the circuit model, the whole circuit analysis is more accurate. When it is implemented correctly, integrated magnetics technique can produce a significant reduction in the magnetic core content number and it can also result in cost efficient designs with less weight and smaller volume. These will increase the whole converter's power density and power efficiency. For high output current and low output voltage applications, half bridge in primary and current doublers in secondary are proved to be a very good solution. Based on this topology, four different integrated magnetics structures are analyzed and compared with each other. One unified model is introduced and implemented in the circuit analysis. A new integrated magnetics component core shape is proposed. All simulation and experimental results verify the integrated magnetics design. There are several new magnetics components applications shown in the dissertation. Active transient voltage compensator is a good solution to the challenging high slew rate load current transient requirement of VRM. The transformer works as an extra voltage source. During the transient periods, the transformer injects or absorbs the extra transient to or from the circuit. A peak current mode controlled integrated magnetics structure is proposed in the dissertation. Two transformers and two inductors are integrated in one core. It can force the two input capacitors of half bridge topology to have the same voltage potential and solve the voltage unbalance issue. The proposed integrated magnetics structure is simple compared with other methods implementing the current mode control to half bridge topology. Circuit analysis, simulation and experimental results verify the feasibility of these applications.
Show less - Date Issued
- 2007
- Identifier
- CFE0001823, ucf:47341
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001823
- Title
- DESIGN FOR AUDITORY DISPLAYS: IDENTIFYING TEMPORAL AND SPATIAL INFORMATION CONVEYANCE PRINCIPLES.
- Creator
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Ahmad, Ali, Stanney, Kay, University of Central Florida
- Abstract / Description
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Designing auditory interfaces is a challenge for current human-systems developers. This is largely due to a lack of theoretical guidance for directing how best to use sounds in today's visually-rich graphical user interfaces. This dissertation provided a framework for guiding the design of audio interfaces to enhance human-systems performance. This doctoral research involved reviewing the literature on conveying temporal and spatial information using audio, using this knowledge to build...
Show moreDesigning auditory interfaces is a challenge for current human-systems developers. This is largely due to a lack of theoretical guidance for directing how best to use sounds in today's visually-rich graphical user interfaces. This dissertation provided a framework for guiding the design of audio interfaces to enhance human-systems performance. This doctoral research involved reviewing the literature on conveying temporal and spatial information using audio, using this knowledge to build three theoretical models to aid the design of auditory interfaces, and empirically validating select components of the models. The three models included an audio integration model that outlines an end-to-end process for adding sounds to interactive interfaces, a temporal audio model that provides a framework for guiding the timing for integration of these sounds to meet human performance objectives, and a spatial audio model that provides a framework for adding spatialization cues to interface sounds. Each model is coupled with a set of design guidelines theorized from the literature, thus combined, the developed models put forward a structured process for integrating sounds in interactive interfaces. The developed models were subjected to a three phase validation process that included review by Subject Matter Experts (SMEs) to assess the face validity of the developed models and two empirical studies. For the SME review, which assessed the utility of the developed models and identified opportunities for improvement, a panel of three audio experts was selected to respond to a Strengths, Weaknesses, Opportunities, and Threats (SWOT) validation questionnaire. Based on the SWOT analysis, the main strengths of the models included that they provide a systematic approach to auditory display design and that they integrate a wide variety of knowledge sources in a concise manner. The main weaknesses of the models included the lack of a structured process for amending the models with new principles, some branches were not considered parallel or completely distinct, and lack of guidance on selecting interface sounds. The main opportunity identified by the experts was the ability of the models to provide a seminal body of knowledge that can be used for building and validating auditory display designs. The main threats identified by the experts were that users may not know where to start and end with each model, the models may not provide comprehensive coverage of all uses of auditory displays, and the models may act as a restrictive influence on designers or they may be used inappropriately. Based on the SWOT analysis results, several changes were made to the models prior to the empirical studies. Two empirical evaluation studies were conducted to test the theorized design principles derived from the revised models. The first study focused on assessing the utility of audio cues to train a temporal pacing task and the second study combined both temporal (i.e., pace) and spatial audio information, with a focus on examining integration issues. In the pace study, there were four different auditory conditions used for training pace: 1) a metronome, 2) non-spatial auditory earcons, 3) a spatialized auditory earcon, and 4) no audio cues for pace training. Sixty-eight people participated in the study. A pre- post between subjects experimental design was used, with eight training trials. The measure used for assessing pace performance was the average deviation from a predetermined desired pace. The results demonstrated that a metronome was not effective in training participants to maintain a desired pace, while, spatial and non-spatial earcons were effective strategies for pace training. Moreover, an examination of post-training performance as compared to pre-training suggested some transfer of learning. Design guidelines were extracted for integrating auditory cues for pace training tasks in virtual environments. In the second empirical study, combined temporal (pacing) and spatial (location of entities within the environment) information were presented. There were three different spatialization conditions used: 1) high fidelity using subjective selection of a "best-fit" head related transfer function, 2) low fidelity using a generalized head-related transfer function, and 3) no spatialization. A pre- post between subjects experimental design was used, with eight training trials. The performance measures were average deviation from desired pace and time and accuracy to complete the task. The results of the second study demonstrated that temporal, non-spatial auditory cues were effective in influencing pace while other cues were present. On the other hand, spatialized auditory cues did not result in significantly faster task completion. Based on these results, a set of design guidelines was proposed that can be used to direct the integration of spatial and temporal auditory cues for supporting training tasks in virtual environments. Taken together, the developed models and the associated guidelines provided a theoretical foundation from which to direct user-centered design of auditory interfaces.
Show less - Date Issued
- 2007
- Identifier
- CFE0001719, ucf:47317
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001719
- Title
- MECHANISMS OF NANOFILTER FOULING AND TREATMENT ALTERNATIVES FOR SURFACE WATER SUPPLIES.
- Creator
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Reiss, Charles, Taylor, James, University of Central Florida
- Abstract / Description
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This dissertation addresses the role of individual fouling mechanisms on productivity decline and solute mass transport in nanofiltration (NF) of surface waters. Fouling mechanisms as well as solute mass transport mechanisms and capabilities must be understood if NF of surface waters is to be successful. Nanofiltration of surface waters was evaluated at pilot-scale in conjunction with advanced pretreatment processes selected for minimization of nanofilter fouling, which constituted several...
Show moreThis dissertation addresses the role of individual fouling mechanisms on productivity decline and solute mass transport in nanofiltration (NF) of surface waters. Fouling mechanisms as well as solute mass transport mechanisms and capabilities must be understood if NF of surface waters is to be successful. Nanofiltration of surface waters was evaluated at pilot-scale in conjunction with advanced pretreatment processes selected for minimization of nanofilter fouling, which constituted several integrated membrane systems (IMSs). Membrane fouling mechanisms of concern were precipitation, adsorption, particle plugging, and attached biological growth. Fouling was addressed by addition of acid and antiscalent for control of precipitation, addition of monochloramine for control of biological growth, microfiltration (MF) or coagulation-sedimentation-filtration (CSF) for control of particle plugging, and in-line coagulation-microfiltration (C/MF) or CSF for control of organic adsorption. Surface water solutes of concern included organic solutes, pathogens, and taste and odor compounds. Solute mass transport was addressed by evaluation of total organic carbon (TOC), Bacillus subtilis endospores, gesomin (G), 2-methlyisoborneol (MIB), and threshold odor number (TON). This evaluation included modeling to determine the role of diffusion in solute mass transport including assessment of the homogeneous solution diffusion equation. A cellulose acetate (CA) NF was less susceptible to fouling than two polyamide (PA) NFs. NF fouling was minimized by the addition of monochloramine, lower flux, lower recovery, and with the use of a coagulant-based pretreatment (C/MF or CSF). NF surface characterization showed that the low fouling CA film was less rough and less negatively charged than the PA films. Thus the theory that a more negatively charged surface would incur less adsorptive fouling, due to charge repulsion, was not observed for these tests. The rougher surface of the PA films may have increased the number of sites for adsorption and offset the charge repulsion benefits of the negatively charged surface. The addition of monochloramine significantly reduced biodegradation and integrity loss of the CA membrane. PA membranes are inherently not biologically degradable due to their chemical structure. Monochloramination reduced the rate of fouling of the PA membrane but resulted in a gradual increase in water mass transfer coefficient and a decrease in TDS rejection over time, which indicated damage and loss of integrity of the PA membrane. Based on surface characterization by X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Spectrometry (FTIR), the PA membrane degradation appeared to be chemically-based and initiated with chlorination of amide nitrogen and/or aromatic rings, which ultimately resulted in disruption of membrane chemical structures. The recommended Integrated Membrane System to control fouling of a surface water nanofiltration system is CSF monochloramine/acid/antiscalent³monochloramine-tolerant NF. This IMS, at low flux and recovery, operated with no discernable fouling and is comparable to a groundwater nanofiltration plant with cleaning frequencies of once per six months or longer. A significant portion of the organic solutes including total organic carbon (TOC) passing through the membranes was diffusion controlled. Permeate concentration increased with increasing recovery and with decreasing flux for both PA and CA membranes. The influence was diminished for the PA membrane, due to its high rejection capabilities. Total rejection of spores used as pathogen surrogates was not achieved as spores were indigenous and high spore concentrations were used in all challenge studies; however, Integrated Membrane System spore rejection exceeded credited regulatory rejection of similar sized microorganisms by conventional treatment by several logs. Spore rejection varied by NF but only slightly by MF as size-exclusion controlled. There was no difference among spore rejection of IMS with and without in-line coagulation. Consequently, these results indicate membrane configuration (Hollow fiber>Spiral Wound) and membrane film (Composite Thin Film>CA) significantly affected spore rejection. Geosmin and methylisoborneol have molecular weights of 182 and 168 respectively, and are byproducts of algal blooms, which commonly increase taste and odor as measured by the threshold odor number (TON) in drinking water. Although these molecules are neutral and were thought to pass through NFs, challenge testing of IMS unit operations found that significant removal of TON, G and MIB was achieved by membrane processes, which was far superior to conventional processes. A CA NF consistently removed 35 to 50 percent of TON, MIB, and G, but did not achieve compliance with the TON standard of 3 units. A PA NF provided over 99 percent removal of MIB and G. Challenge tests using MIB and G indicated that size-exclusion controlled mass transfer of these compounds in NF membranes.
Show less - Date Issued
- 2005
- Identifier
- CFE0000630, ucf:46506
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000630
- Title
- CIRCUIT DESIGN AND RELIABILITY OF A CMOS RECEIVER.
- Creator
-
Yang, Hong, Yuan, Jiann, University of Central Florida
- Abstract / Description
-
This dissertation explores CMOS RF design and reliability for portable wireless receivers. The objective behind this research is to achieve an increase in integration level, and gain more understanding for RF reliability. The fields covered include device, circuit and system. What is under investigation is a multi-band multi-mode receiver with GSM, DCS-1800 and CDMA compatibility. To my understanding, GSM and CDMA dual-mode mobile phones are progressively investigated in industries, and few...
Show moreThis dissertation explores CMOS RF design and reliability for portable wireless receivers. The objective behind this research is to achieve an increase in integration level, and gain more understanding for RF reliability. The fields covered include device, circuit and system. What is under investigation is a multi-band multi-mode receiver with GSM, DCS-1800 and CDMA compatibility. To my understanding, GSM and CDMA dual-mode mobile phones are progressively investigated in industries, and few commercial products are available. The receiver adopts direct conversion architecture. Some improved circuit design methods are proposed, for example, for low noise amplifier (LNA). Except for band filters, local oscillators, and analog-digital converters which are usually implemented by COTS SAW filters and ICs, all the remaining blocks such as switch, LNA, mixer, and local oscillator are designed in MOSIS TSMC 0.35ìm technology in one chip. Meanwhile, this work discusses related circuit reliability issues, which are gaining more and more attention. Breakdown (BD) and hot carrier (HC) effects are important issues in semiconductor industry. Soft-breakdown (SBD) and HC effects on device and RF performance has been reported. Hard-breakdown (HBD) effects on digital circuits have also been investigated. This work uniquely address HBD effects on the RF device and circuit performance, taking low noise amplifier and power amplifier as targets.
Show less - Date Issued
- 2004
- Identifier
- CFE0000212, ucf:46259
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000212
- Title
- THE USE OF YOGA FOR CHRONIC PAIN MANAGEMENT IN THE PEDIATRIC POPULATION.
- Creator
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Huff, Annabeth, Burr, Joyce, University of Central Florida
- Abstract / Description
-
Chronic pain has an adverse impact on the quality of life in children and adolescents. It can impair a child's physical, psychological, and social functioning, leading to lower satisfaction with life and poor self-image related to health status. Forty-five percent of children experience chronic pain related to either disease processes or idiopathic causes. Not all children who suffer from chronic pain respond to traditional therapies. The purpose of this literature review was evaluation of...
Show moreChronic pain has an adverse impact on the quality of life in children and adolescents. It can impair a child's physical, psychological, and social functioning, leading to lower satisfaction with life and poor self-image related to health status. Forty-five percent of children experience chronic pain related to either disease processes or idiopathic causes. Not all children who suffer from chronic pain respond to traditional therapies. The purpose of this literature review was evaluation of current research on the use of yoga as an integrative therapy for chronic pain management in the pediatric population. A database search of CINAHL, MEDLINE, and PsycINFO was conducted. Yoga has few side effects, is inexpensive, and can be practiced almost anywhere, regardless of physical ability or age. There is limited research on the use of yoga as an intervention within the pediatric population. Existing research supports the efficacy of yoga for chronic pain management.
Show less - Date Issued
- 2015
- Identifier
- CFH0004798, ucf:45332
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004798
- Title
- INTEGRATED OPTICAL SPR (SURFACE PLASMON RESONANCE) SENSOR BASED ON OPTOELECTRONIC PLATFORM.
- Creator
-
Bang, Hyungseok, LiKamWa, Patrick, University of Central Florida
- Abstract / Description
-
Current major demands in SPR sensor development are system miniaturization and throughput improvement. Structuring an array of integrated optical SPR sensor heads on a semiconductor based optoelectronic platform could be a promising solution for those issues, since integrated optical waveguides have highly miniaturized dimension and the optoelectronic platform enables on-chip optical-to-electrical signal conversion. Utilizing a semiconductor based platform to achieve optoelectronic...
Show moreCurrent major demands in SPR sensor development are system miniaturization and throughput improvement. Structuring an array of integrated optical SPR sensor heads on a semiconductor based optoelectronic platform could be a promising solution for those issues, since integrated optical waveguides have highly miniaturized dimension and the optoelectronic platform enables on-chip optical-to-electrical signal conversion. Utilizing a semiconductor based platform to achieve optoelectronic functionality poses requirements to the senor head; the sensor head needs to have reasonably small size while it should have reasonable sensitivity and fabrication tolerance. This research proposes a novel type of SPR sensor head and demonstrates a fabricated device with an array of integrated optical SPR sensor heads endowed with optoelectronic functionality. The novel integrated optical SPR sensor head relies on mode conversion efficiency for its operational principle. The beauty of this type of sensor head is it can produce clear contrast in SPR spectrum with a highly miniaturized and simple structure, in contrast to several-millimeter-scale conventional absorption type or interferometer type sensor heads. The integrated optical SPR sensor with optoelectronic functionality has been realized by structuring a dielectric waveguide based SPR sensor head on a photodetector-integrated semiconductor substrate. A large number of unit sensors have been fabricated on a substrate with a batch fabrication process, which promises a high throughput SPR sensor system or low-priced disposable sensors.
Show less - Date Issued
- 2008
- Identifier
- CFE0002312, ucf:47841
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002312
- Title
- MONOLITHICALLY INTEGRATED WAVELENGTH TUNABLE LASER DIODE FOR INTEGRATED OPTIC SURFACE PLASMON RESONANCE SENSING.
- Creator
-
Tabbakh, Thamer, Likamwa, Patrick, Batarseh, Issa, Fathpour, Sasan, Mikhael, Wasfy, Khajavikhan, Mercedeh, University of Central Florida
- Abstract / Description
-
In this work, we demonstrate an InGaAsP multiple quantum well tunable laser diode that amalgamates two gain sections with different bandgap energies. This is achieved using selective area intermixing of the multiple quantum wells, and impurity-free vacancy induced disordering. When different current combination is injected into each section, that leads to a laser wavelength peak whose position depends on the relative magnitudes of the two injected currents. The laser wavelength can be fine...
Show moreIn this work, we demonstrate an InGaAsP multiple quantum well tunable laser diode that amalgamates two gain sections with different bandgap energies. This is achieved using selective area intermixing of the multiple quantum wells, and impurity-free vacancy induced disordering. When different current combination is injected into each section, that leads to a laser wavelength peak whose position depends on the relative magnitudes of the two injected currents. The laser wavelength can be fine-tuned from 1538 nm to 1578 nm with relatively constant output power. The free spectral range FSR of the tunable laser found to be 0.25 nm. This tunable laser was launched into an optical surface plasmon resonance sensor head to provide an input light source for the SPR sensor.Using the tunable laser diode, we have demonstrated an optical surface plasmon resonance sensor head that is based on an inverted rib dielectric waveguide, in which the resonance wavelength of the surface plasmon excited at the gold metal-dielectric interface depends on the refractive index of the liquid in contact with it. The inverted-rib waveguide of the SPR sensor head is made of a layer of SU-8 polymer with a refractive index of 1.568. While the lower cladding layer consists of silicon oxynitride (SiOxNy) with a refractive index of 1.526. The top surface is coated with 20 nm of chromium followed by a 50 nm thick layer of gold or with 4 nm of titanium followed by a 25 nm thick layer of gold. The SPR sensor head was designed, to allow monitoring of analyte media with a refractive index, ranging from 1.43 to the 1.52. Using a set of reference liquids representing the analyte medium, the sensitivity of the SPR sensor was measured using the fabricated tunable laser, an optical spectrum analyzer, and a photodiode. It was found that with various calibrated sample liquids in contact with the gold metal, a sharp resonance dip in the transmission spectrum occurred, and its position shifted to a shorter wavelength when the refractive index of the sample liquids was increased. The average sensitivity of the SPR sensor devices was determined to be S = 334 nm/RIU.
Show less - Date Issued
- 2018
- Identifier
- CFE0007769, ucf:52390
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007769
- Title
- THE EFFICACY OF A 6-WEEK EVIDENCE-BASED SUPPORT GROUP FOR CAREGIVERS OF DEMENTIA IN A PRIMARY CARE SETTING.
- Creator
-
Shah, Mona, Paulson, Daniel, Cassisi, Jeffrey, Sims, Valerie, University of Central Florida
- Abstract / Description
-
More than 16 million Americans provide unpaid care for those with Alzheimer's disease and other dementias. Extant literature has well documented the increased risk for physical, emotional, social and financial burden associated with caregiving. While intensive support groups may be well-suited to caregiver needs, they are often difficult to implement given financial, personnel and resource constraints. Thus, the purpose of this study is to examine the efficacy of a theoretically-based, 6-week...
Show moreMore than 16 million Americans provide unpaid care for those with Alzheimer's disease and other dementias. Extant literature has well documented the increased risk for physical, emotional, social and financial burden associated with caregiving. While intensive support groups may be well-suited to caregiver needs, they are often difficult to implement given financial, personnel and resource constraints. Thus, the purpose of this study is to examine the efficacy of a theoretically-based, 6-week caregiver support group in a community primary care setting. The group focuses on self-care, behavior management techniques and interdisciplinary caregiver resources. A total of 22 participants completed the active caregiver support group and they were compared to 19 control participants who participated in community caregiver support groups. Participants on average were in their mid-60s, mostly female and Caucasian, and identified as either the care recipient's child or spouse. All participants completed self-report measures related to demographic information, caregiver preparedness (Caregiver Preparedness Scale), caregiver strain (Caregiver Strain Index), caregiver depressive symptoms (CESD-10), and care recipient's neuropsychiatric symptoms (NPI-Q), at baseline and at 6-weeks. Participants in the active caregiver support group also completed a satisfaction survey. Results from two-way mixed ANCOVA analyses revealed a time by group interaction effect for caregiver preparedness, such that caregivers in the active group demonstrated a significant increase in mean caregiver preparedness scores while scores remained invariant for the control group. No significant main effects nor group by time interaction effects were found for caregiver strain, caregiver depressive symptoms and caregiver distress related to neuropsychiatric symptoms. Participants in the active caregiver support group rated being largely satisfied with the group. Results suggest that this 6-week caregiver support group may be a promising caregiver intervention that can be readily implemented and accessible in primary care clinics. Further research with larger sample sizes is recommended.
Show less - Date Issued
- 2018
- Identifier
- CFE0007370, ucf:52098
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007370
- Title
- Technology Implementation in K-12 Schools: A Research Study of Perceptions and Practice.
- Creator
-
Martinez, Kaitlin, Flammia, Madelyn, Jones, Daniel, Applen, John, University of Central Florida
- Abstract / Description
-
According to the National Center for Education Statistics, even though 97% of classrooms have at least one instructional computer available, only 40% of teachers in public schools (including elementary and secondary) report using computers in the classroom often. My project aims to illustrate the barriers that are keeping K-12 teachers from integrating technology in their classrooms, such as the lack of availability for training, teacher's lack of knowledge or schooling, or a lack of IT...
Show moreAccording to the National Center for Education Statistics, even though 97% of classrooms have at least one instructional computer available, only 40% of teachers in public schools (including elementary and secondary) report using computers in the classroom often. My project aims to illustrate the barriers that are keeping K-12 teachers from integrating technology in their classrooms, such as the lack of availability for training, teacher's lack of knowledge or schooling, or a lack of IT support. It also discusses possible solutions to the problem, such as teacher training and better resources. By assessing the Level of Technology Integration, or LoTi, we can learn how much or how often a teacher is using technology in a classroom. My project consists of conducting a research study that will aim to reinforce the hypothesis that the LoTi in K-12 schools is lower than expected, considering the availability of computers and technology. By learning the severity of the obstacles teachers face, we can work on possible solutions. The findings of this study were that teachers face barriers that inhibit them from implementing technology no matter what type of school environment they are in. These barriers come from lack of time, access, but most strongly from the self-efficacy of the teachers. Teachers need professional development and training to develop their skills and confidence, which will positively impact students, the school, and the overall education system.
Show less - Date Issued
- 2012
- Identifier
- CFE0004503, ucf:49279
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004503
- Title
- Wavelength scale resonant structures for integrated photonic applications.
- Creator
-
Weed, Matthew, Schoenfeld, Winston, Moharam, M., Likamwa, Patrick, Delfyett, Peter, Leuenberger, Michael, University of Central Florida
- Abstract / Description
-
An approach to integrated frequency-comb filtering is presented, building from a background in photonic crystal cavity design and fabrication. Previous work in the development of quantum information processing devices through integrated photonic crystals consists of photonic band gap engineering and methods of on-chip photon transfer. This work leads directly to research into coupled-resonator optical waveguides which stands as a basis for the primary line of investigation. These coupled...
Show moreAn approach to integrated frequency-comb filtering is presented, building from a background in photonic crystal cavity design and fabrication. Previous work in the development of quantum information processing devices through integrated photonic crystals consists of photonic band gap engineering and methods of on-chip photon transfer. This work leads directly to research into coupled-resonator optical waveguides which stands as a basis for the primary line of investigation. These coupled cavity systems offer the designer slow light propagation which increases photon lifetime, reduces size limitations toward on-chip integration, and offers enhanced light-matter interaction. A unique resonant structure explained by various numerical models enables comb-like resonant clusters in systems that otherwise have no such regular resonant landscape (e.g. photonic crystal cavities). Through design, simulation, fabrication and test, the work presented here is a thorough validation for the future potential of coupled-resonator filters in frequency comb laser sources.
Show less - Date Issued
- 2013
- Identifier
- CFE0004957, ucf:49568
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004957
- Title
- Non-Reciprocal Wave Transmission in Integrated Waveguide Array Isolators.
- Creator
-
Ho, Yat, Likamwa, Patrick, Christodoulides, Demetrios, Vanstryland, Eric, Kaup, David, University of Central Florida
- Abstract / Description
-
Non-reciprocal wave transmission is a phenomenon witnessed in certain photonic devices when the wave propagation dynamics through the device along one direction differs greatly from the dynamics along the counter-propagating direction. Specifically, it refers to significant power transfer occurring in one direction, and greatly reduced power transfer in the opposite direction. The resulting effect is to isolate the directionality of wave propagation, allowing transmission to occur along one...
Show moreNon-reciprocal wave transmission is a phenomenon witnessed in certain photonic devices when the wave propagation dynamics through the device along one direction differs greatly from the dynamics along the counter-propagating direction. Specifically, it refers to significant power transfer occurring in one direction, and greatly reduced power transfer in the opposite direction. The resulting effect is to isolate the directionality of wave propagation, allowing transmission to occur along one direction only.Given the popularity of photonic integrated circuits (PIC), in which all the optical components are fabricated on the same chip so that the entire optical system can be made more compact, it is desirable to have an easily integrated optical isolator. Common free-space optical isolator designs, which rely on the Faraday effect, are limited by the availability of suitable magnetic materials. This research proposes a novel integrated optical isolator based on an array of closely spaced, identical waveguides. Because of the nonlinear optical properties of the material, this device exploits the differing behaviors of such an array when illuminated with either a high power or a low power beam to achieve non-reciprocal wave transmission in the forwards and backwards directions, respectively. The switching can be controlled electro-optically via an integrated gain section which provides optical amplification before the input to the array. The design, fabrication, characterization and testing of this optical isolator are covered in this dissertation. We study the switching dynamics of this device and present its optimum operating conditions. ?
Show less - Date Issued
- 2012
- Identifier
- CFE0004305, ucf:49495
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004305
- Title
- AN EVALUATION OF INTEGRATED CURRICULUM AS IT EXISTS IN MATHEMATICS AND SCIENCE SSS AS WELL AS THE SUBSEQUENT SUPPORTIVE PRESENTATION OF THOSE STANDARDS IN EIGHTH GRADE MATHEMATICS AND SCIENCE TEXTBOOKS.
- Creator
-
Gill, Clara, Dixon, Juli, University of Central Florida
- Abstract / Description
-
This study attempted to verify points of intersection (POIs) between mathematics and science in the eighth grade Sunshine State Standards (SSS), and to develop a valid and reliable instrument to evaluate these POIs as they were presented in the respective mathematics and science textbooks approved for use in Florida public schools. Shannon and Weaver (1998) delineated a process for content analysis that informed the design of this analysis. The process began with an analysis of the SSS to...
Show moreThis study attempted to verify points of intersection (POIs) between mathematics and science in the eighth grade Sunshine State Standards (SSS), and to develop a valid and reliable instrument to evaluate these POIs as they were presented in the respective mathematics and science textbooks approved for use in Florida public schools. Shannon and Weaver (1998) delineated a process for content analysis that informed the design of this analysis. The process began with an analysis of the SSS to uncover POIs between mathematics and science; considered effective strategies for presenting these points of intersection in the classroom; and examined the textbooks for a mutually supportive presentation of the POIs between the two domains. The criterion for textbook evaluation was synthesized from documents used by the National Research Council (NRC, 2004) and Project 2061 (Roseman, Kulm, Shuttleworth, 2001. These criteria were examined in terms of measureable elements of textbook design, vocabulary, inquiry and problem solving in order to create integrated objectives, which were then operationalized so that each objective could be evaluated using the Textbook Evaluation Document (TED). The validity of the TED was insured by the transparency of the process. Reliability was determined in two steps, first to determine the most reliable segments of the document and finally to confirm the reliability of those segments. It was determined that the vocabulary section of the TED consistently produced reliability scores above 70% with variation of Supportive Curriculum Scores (SCS) between textbooks. This indicated that a measure of supportive vocabulary could be generated for use in future studies for example correlating supportive curriculum with student achievement.
Show less - Date Issued
- 2010
- Identifier
- CFE0003010, ucf:48338
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003010
- Title
- DATA-TRUE CHARACTERIZATION OF NEURONAL MODELS.
- Creator
-
Suarez, Jose, Behal, Aman, University of Central Florida
- Abstract / Description
-
In this thesis, a weighted least squares approach is initially presented to estimate the parameters of an adaptive quadratic neuronal model. By casting the discontinuities in the state variables at the spiking instants as an impulse train driving the system dynamics, the neuronal output is represented as a linearly parameterized model that depends on ltered versions of the input current and the output voltage at the cell membrane. A prediction errorbased weighted least squares method is...
Show moreIn this thesis, a weighted least squares approach is initially presented to estimate the parameters of an adaptive quadratic neuronal model. By casting the discontinuities in the state variables at the spiking instants as an impulse train driving the system dynamics, the neuronal output is represented as a linearly parameterized model that depends on ltered versions of the input current and the output voltage at the cell membrane. A prediction errorbased weighted least squares method is formulated for the model. This method allows for rapid estimation of model parameters under a persistently exciting input current injection. Simulation results show the feasibility of this approach to predict multiple neuronal ring patterns. Results of the method using data from a detailed ion-channel based model showed issues that served as the basis for the more robust resonate-and- re model presented. A second method is proposed to overcome some of the issues found in the adaptive quadratic model presented. The original quadratic model is replaced by a linear resonateand- re model -with stochastic threshold- that is both computational efficient and suitable for larger network simulations. The parameter estimation method presented here consists of different stages where the set of parameters is divided in to two. The rst set of parameters is assumed to represent the subthreshold dynamics of the model, and it is estimated using a nonlinear least squares algorithm, while the second set is associated with the threshold and reset parameters as its estimated using maximum likelihood formulations. The validity of the estimation method is then tested using detailed Hodgkin-Huxley model data as well as experimental voltage recordings from rat motoneurons.
Show less - Date Issued
- 2011
- Identifier
- CFE0003917, ucf:48724
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003917