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 Title
 Causality between stock prices and exchange rates: A case of the United States.
 Creator
 Ozair, Amber., Florida Atlantic University, Yuhn, Kyhyang
 Abstract/Description

This thesis investigates the direction of causality as well as shortrun dynamics and longrun equilibrium relationship between stock prices and exchange rates using quarterly data for the period 1960:12004:4. The studies apply techniques of the unit root, cointegration and Standard Granger causality tests to examine the relationship between these two financial variables. The empirical results reveal that there is no causal linkage and no cointegration between the stock prices and exchange...
Show moreThis thesis investigates the direction of causality as well as shortrun dynamics and longrun equilibrium relationship between stock prices and exchange rates using quarterly data for the period 1960:12004:4. The studies apply techniques of the unit root, cointegration and Standard Granger causality tests to examine the relationship between these two financial variables. The empirical results reveal that there is no causal linkage and no cointegration between the stock prices and exchange rates as suggested under Traditional and Portfolio approaches. The results support the view that the semistrong form of EMH holds true for the U.S. financial markets.
Show less  Date Issued
 2006
 PURL
 http://purl.flvc.org/fcla/dt/13393
 Subject Headings
 Econometric models, Business forecastingMathematical models, Efficient market theory, Stock exchangesMathematical models
 Format
 Document (PDF)
 Title
 Hydrodynamic analysis of ocean current turbines using vortex lattice method.
 Creator
 Goly, Aneesh, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

The main objective of the thesis is to carry out a rigorous hydrodynamic analysis of ocean current turbines and determine power for a range of flow and geometric parameters. For the purpose, a computational tool based on the vortex lattice method (VLM) is developed. Velocity of the flow on the turbine blades, in relation to the freestream velocity, is determined through induction factors. The geometry of trailing vortices is taken to be helicoidal. The VLM code is validated by comparing its...
Show moreThe main objective of the thesis is to carry out a rigorous hydrodynamic analysis of ocean current turbines and determine power for a range of flow and geometric parameters. For the purpose, a computational tool based on the vortex lattice method (VLM) is developed. Velocity of the flow on the turbine blades, in relation to the freestream velocity, is determined through induction factors. The geometry of trailing vortices is taken to be helicoidal. The VLM code is validated by comparing its results with other theoretical and experimental data corresponding to flows about finiteaspect ratio foils, swept wings and a marine current turbine. The validated code is then used to study the performance of the prototype gulfstream turbine for a range of parameters. Power and thrust coefficients are calculated for a range of tip speed ratios and pitch angles. Of all the cases studied, the one corresponding to tip speed ratio of 8 and uniform pitch angle 20 produced the maximum power of 41.3 [kW] in a current of 1.73 [m/s]. The corresponding power coefficient is 0.45 which is slightly less than the Betz limit power coefficient of 0.5926. The VLM computational tool developed for the research is found to be quite efficient in that it takes only a fraction of a minute on a regular laptop PC to complete a run. The tool can therefore be efficiently used or integrated into software for design optimization.
Show less  Date Issued
 2010
 PURL
 http://purl.flvc.org/FAU/2683131
 Subject Headings
 Marine turbines, Mathematical models, Water currents, Forecasting, Mathematical models, Aerodynamics, Mathematics, Finite element method
 Format
 Document (PDF)
 Title
 Aerodynamic analysis of a propeller in a turbulent boundary layer flow.
 Creator
 Lachowski, Felipe Ferreira., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

Simulating the exact chaotic turbulent flow field about any geometry is a dilemma between accuracy and computational resources, which has been continuously studied for just over a hundred years. This thesis is a complete walkthrough of the entire process utilized to approximate the flow ingested by a Seviktype rotor based on solutions to the Reynolds Averaged NavierStokes equations (RANS). The Multiple Reference Frame fluid model is utilized by the code of ANSYSFLUENT and results are...
Show moreSimulating the exact chaotic turbulent flow field about any geometry is a dilemma between accuracy and computational resources, which has been continuously studied for just over a hundred years. This thesis is a complete walkthrough of the entire process utilized to approximate the flow ingested by a Seviktype rotor based on solutions to the Reynolds Averaged NavierStokes equations (RANS). The Multiple Reference Frame fluid model is utilized by the code of ANSYSFLUENT and results are validated by experimental wake data. Three open rotor configurations are studied including a uniform inflow and the rotor near a plate with and without a thick boundary layer. Furthermore, observations are made to determine the variation in velocity profiles of the ingested turbulent flow due to varying flow conditions.
Show less  Date Issued
 2013
 PURL
 http://purl.flvc.org/fcla/dt/3360798
 Subject Headings
 Acoustical engineering, Boundary layer control, Multiphase flow, Mathematical models, Fluid mechanics, Mathematical models, Turbulence, Mathematical models, Computatioinal fluid dynamics
 Format
 Document (PDF)
 Title
 Efficient leeway drift prediction.
 Creator
 Lee, Yanhua., Florida Atlantic University, Su, TsungChow, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

Search and rescue of crafts in distress on the sea surface require the capability to accurately predict the drift of target craft in a short time. A nonlinear mathematical model (original model) has been developed as a tool for the study of the boat drift. Wind load computation considers the wind gradient and the vessel geometry. The current loads include form and friction drag. From the numerical evaluations, the effects of various environmental and vehical parameters on drift are properly...
Show moreSearch and rescue of crafts in distress on the sea surface require the capability to accurately predict the drift of target craft in a short time. A nonlinear mathematical model (original model) has been developed as a tool for the study of the boat drift. Wind load computation considers the wind gradient and the vessel geometry. The current loads include form and friction drag. From the numerical evaluations, the effects of various environmental and vehical parameters on drift are properly accounted for. Simplification of the original model results in a model which is computationally 60 times faster, socalled version 1, without losing much accuracy. In order to meet the needs of two minute prediction for practical implementation, a further simplified model, version 2, was developed from version 1. It is found that the computing speed can be improved one hundred times, and this will facilitate the practical implementation of FAU model in search planning.
Show less  Date Issued
 1989
 PURL
 http://purl.flvc.org/fcla/dt/14499
 Subject Headings
 Search and rescue operationsMathematical models, Ocean currentsMathematical models, WindsSpeedMathematical models
 Format
 Document (PDF)
 Title
 A SHORT RUN MACROECONOMETRIC MODEL OF THE GREEK ECONOMY, 19561969.
 Creator
 TSOUBLEKAS, GEORGE BASIL., Florida Atlantic University, Scheidell, John M., College of Business, Department of Economics
 Abstract/Description

Tho basis of this study is a macroeconometric model of Greece that consists of fifteen equations estimated by ordinary least squares methods from annual data and five definitional aggregates. The model is designed primarily to explain the behavior of the Greek economy from 1953, but it also has value for short run forecasting. A unique feature is the emphasis given to the interplay of imports, investment and exports. The stability test indicates a stable model with a damped oscillation of a...
Show moreTho basis of this study is a macroeconometric model of Greece that consists of fifteen equations estimated by ordinary least squares methods from annual data and five definitional aggregates. The model is designed primarily to explain the behavior of the Greek economy from 1953, but it also has value for short run forecasting. A unique feature is the emphasis given to the interplay of imports, investment and exports. The stability test indicates a stable model with a damped oscillation of a twentyfive period cycle. The predictive ability tests were very favorable and the DurbinWatson tests indicated low autocorrelation. Future forecasts were made with the use of trend estimated values for the exogenous variables. Finally, the analysis of multipliers was used to evaluate the policy implications of the model.
Show less  Date Issued
 1973
 PURL
 http://purl.flvc.org/fcla/dt/13596
 Subject Headings
 MacroeconomicsMathematical models, GreeceEconomic policyMathematical models, GreeceEconomic conditionsMathematical models
 Format
 Document (PDF)
 Title
 Mathematical modeling of plankton patchiness.
 Creator
 Ather, Simantha S., Noonburg, Erik G., Graduate College
 Date Issued
 20110408
 PURL
 http://purl.flvc.org/fcla/dt/3164458
 Subject Headings
 Marine plankton, Marine zooplankton, Mathematical models
 Format
 Document (PDF)
 Title
 Fractal ionchannel behavior generates fractal firing patterns in neuronal models.
 Creator
 Liebovitch, Larry S., Lowen, Steven B., White, John A.
 Date Issued
 199905
 PURL
 http://purl.flvc.org/fau/165477
 Subject Headings
 BiophysicsResearch, Fractals, Neural networks (Neurobiology)Mathematical models, NeuronsMathematical models, Markov processesMathematical models, Ion channelsMathematical models
 Format
 Document (PDF)
 Title
 INVESTMENT SPENDING IN THE UNITED STATES: AN ANALYSIS OF SOME ECONOMETRIC ISSUES.
 Creator
 SADIKU, CHRISTIANAH YEMISI., Florida Atlantic University, Stronge, William B., College of Business, Department of Economics
 Abstract/Description

This thesis examines the determinants of that part of national gross fixed investment which is undertaken by the private sector. Any investment process is subject to a number of separate time lags,and as a result, lagged explanatory variables were used in this study to explain the past trends and the recent surge in capital spending. The cashflow and q models distinguished themselves from other models as relatively accurate descriptive of investment spending. It should be noted, however, that...
Show moreThis thesis examines the determinants of that part of national gross fixed investment which is undertaken by the private sector. Any investment process is subject to a number of separate time lags,and as a result, lagged explanatory variables were used in this study to explain the past trends and the recent surge in capital spending. The cashflow and q models distinguished themselves from other models as relatively accurate descriptive of investment spending. It should be noted, however, that the description of investment spending that appears to have worked well in the past does not have to work so well in the future because economic conditions change.
Show less  Date Issued
 1987
 PURL
 http://purl.flvc.org/fcla/dt/14375
 Subject Headings
 InvestmentsUnited StatesMathematical models
 Format
 Document (PDF)
 Title
 MATHEMATICAL MODELING OF CRAFT DRIFT IN AN OCEAN ENVIRONMENT.
 Creator
 KANG, SIN YOUNG., Florida Atlantic University, Su, TsungChow, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

A mathematical model, which accounts for the essential effects of environmental loads and vehicle characteristics from a fluid dynamics point of view, is developed to forecast the position of a craft drifting on the sea surface. The study is intended to provide a better understanding of the dynamics of drift and thus to provide a reliable model of drift prediction for use in future search and rescue mission. In the mathematical formulation, three degrees of freedom (surge, sway and yaw) of a...
Show moreA mathematical model, which accounts for the essential effects of environmental loads and vehicle characteristics from a fluid dynamics point of view, is developed to forecast the position of a craft drifting on the sea surface. The study is intended to provide a better understanding of the dynamics of drift and thus to provide a reliable model of drift prediction for use in future search and rescue mission. In the mathematical formulation, three degrees of freedom (surge, sway and yaw) of a craft are analyzed, since they play the most significant role in the drift prediction problem. The governing equations of motions are derived from Newton's law of dynamics and the environmental loads considered are the forces and moments exerted by wind, current and waves. The forces are analyzed in terms of drag, lift, and inertial forces. The moments are obtained by summing the contribution from the above forces. For the computation of the wind loads, the wind gradient as well as craft geometry is accounted for. In the current loads, profile, friction and propeller drags are included. The wave forces are computed by the use of wave spectral density. The formulation includes the effects of craft rotation as well as craft translation. A computer algorithm for the mathematical model is implemented to obtain the numerical result in the time domain. The model is verified by comparing its result with field measurements. For this purpose, a field test was carried out. The agreement between the computed and field measured drift path was excellent. The real time prediction capability of the model was ascertained.
Show less  Date Issued
 1987
 PURL
 http://purl.flvc.org/fcla/dt/11894
 Subject Headings
 ShipsHydrodynamicsMathematical models, Ocean waves
 Format
 Document (PDF)
 Title
 Mathematical model of the dynamics of psychotherapy.
 Creator
 Norman, Michael D., Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
 Abstract/Description

This is a novel attempt to produce a rigorous mathematical model of a complex system. The complex system under study is the relationship between therapists and their clients. The success of psychotherapy depends on the nature of the relationship between a therapist and a client. We use dynamical systems theory to model the dynamics of the emotional interaction between a therapist and client. We determine how the therapeutic endpoint and the dynamics of getting there depend on the parameters...
Show moreThis is a novel attempt to produce a rigorous mathematical model of a complex system. The complex system under study is the relationship between therapists and their clients. The success of psychotherapy depends on the nature of the relationship between a therapist and a client. We use dynamical systems theory to model the dynamics of the emotional interaction between a therapist and client. We determine how the therapeutic endpoint and the dynamics of getting there depend on the parameters of the model. ... We describe the emotional state of both the therapist and client with coupled, first order, nonlinear ordinary differential equations (ODE's). The rate of change of the emotional state of the therapist and client is proportional to their previous state, their uninfluenced state when alone, and an influence function which depends on the state of the other person. We formulated influence functions based on the research literature on psychotherapy and the therapeutic alliance. We then determined the critical points from the intersection of the nullclines and used a numerical ODE solver (Matlab ODE113) to compute the trajectories from different initial conditions. ... The results validate this prototypical approach to psychotherapy ; we have shown that human interaction (in the context of psychotherapy) can be quantified and modeled using differential equations.
Show less  Date Issued
 2012
 PURL
 http://purl.flvc.org/FAU/3358758
 Subject Headings
 Psychotherapist and patient, Mathematical models, Counselor and client, Mathematical models, Therapeutic alliance, Mathematical models, Psychotherapy, Philosophy, Mathematical models, Evidencebased psychotherapy, Transference (Psychology), Countertransference (Psychology)
 Format
 Document (PDF)
 Title
 Numerical Simulation of Marine Hydrokinetic Turbines in Realistic Operating Conditions.
 Creator
 Dunlap, Broc, VanZwieten, James, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
 Abstract/Description

Marine Hydrokinetic (MHK) energy is an alternative to address the demand for cleaner energy sources. This study advanced numerical modeling tools and uses these to evaluate the performance of both a Tidal Turbine (TT) and an Ocean Current Turbine (OCT) operating in a variety of conditions. Inflow models are derived with current speeds ranging from 1.5 to 3 m/s and Turbulence Intensities (TI) of 515% and integrated into a TT simulation. An OCT simulation representing a commercial scale 20 m...
Show moreMarine Hydrokinetic (MHK) energy is an alternative to address the demand for cleaner energy sources. This study advanced numerical modeling tools and uses these to evaluate the performance of both a Tidal Turbine (TT) and an Ocean Current Turbine (OCT) operating in a variety of conditions. Inflow models are derived with current speeds ranging from 1.5 to 3 m/s and Turbulence Intensities (TI) of 515% and integrated into a TT simulation. An OCT simulation representing a commercial scale 20 m diameter turbine moored to the seafloor via underwater cable is enhanced with the capability to ingest Acoustic Doppler Current Profiler (ADCP) data and simulate fault conditions. ADCP measurements collected off the coast of Ft. Lauderdale during Hurricanes Irma and Maria were postprocessed and used to characterize the OCT performance. In addition, a set of common faults were integrated into the OCT model to assess the system response in faultinduced scenarios.
Show less  Date Issued
 2022
 PURL
 http://purl.flvc.org/fau/fd/FA00013962
 Subject Headings
 Turbines, Ocean wave power, Simulations, Mathematical models
 Format
 Document (PDF)
 Title
 Nonseparable two dimensional wavelets and their filter banks in polar coordinates.
 Creator
 Andric, Oleg., Florida Atlantic University, Erdol, Nurgun
 Abstract/Description

The problems encountered in development and implementation of orthonormal two dimensional wavelet bases and their filter banks in polar coordinates are addressed. These wavelets and filter banks have possible applications in processing signals that are collected by sensors working in the polar coordinate system, such as biomedical and radar generated signals. The relationship between the space of measurable, squareintegrable functions on the punctured polar coordinate system L^2(P) and space...
Show moreThe problems encountered in development and implementation of orthonormal two dimensional wavelet bases and their filter banks in polar coordinates are addressed. These wavelets and filter banks have possible applications in processing signals that are collected by sensors working in the polar coordinate system, such as biomedical and radar generated signals. The relationship between the space of measurable, squareintegrable functions on the punctured polar coordinate system L^2(P) and space of measurable, squareintegrable functions on the rectangular plane L^2(R^2) is developed. This allows us to develop complete wavelet bases in a more convenient and familiar surrounding of L^2(R^2) and to transport this theory to L^2(P). Corresponding filter banks are also developed. The implementation of wavelet analysis of punctured polar plane is discussed. An example of wavelet bases, filter banks, and implementation is provided.
Show less  Date Issued
 1995
 PURL
 http://purl.flvc.org/fcla/dt/15190
 Subject Headings
 Wavelets (Mathematics), Coordinates, Polar, Signal processingMathematical models
 Format
 Document (PDF)
 Title
 AUTOMATIC STABILIZERS DURING STAGFLATION.
 Creator
 MCINTIRE, RICHARD MICHAEL., Florida Atlantic University, Redman, Milton, College of Business, Department of Economics
 Abstract/Description

This thesis explored the impact of inflation upon fiscal automatic stabilizers during the 197375 recession. Our study confined itself to the three main devices purported to stabilize the U.S. economy automatically: (1) federal personal income tax liability, (2) corporate profits tax liability, and (3) unemployment compensation benefits. A recursive model, similar to that used by Dusenberry, Eckstein, and Fromm to study fiscal automatic stabilizers in the 195758 recession, was constructed....
Show moreThis thesis explored the impact of inflation upon fiscal automatic stabilizers during the 197375 recession. Our study confined itself to the three main devices purported to stabilize the U.S. economy automatically: (1) federal personal income tax liability, (2) corporate profits tax liability, and (3) unemployment compensation benefits. A recursive model, similar to that used by Dusenberry, Eckstein, and Fromm to study fiscal automatic stabilizers in the 195758 recession, was constructed. Our simulation results led us to conclude that there was a substantial reduction in output and employment due to the impact of inflation upon federal personal income tax liability in the 197375 recession. We reached a tentative conclusion that the effects of inflation upon output and employment via corporate profits tax liability were negligible. Finally, we concluded that the effects of inflation upon output and employment via unemployment compensation benefits paid were negligible in the recent stagflation.
Show less  Date Issued
 1978
 PURL
 http://purl.flvc.org/fcla/dt/13919
 Subject Headings
 Economics, Mathematical, United StatesEconomic conditionsMathematical models
 Format
 Document (PDF)
 Title
 What is self organization?.
 Creator
 Liebovitch, Larry S.
 Date Issued
 200604  200608
 PURL
 http://purl.flvc.org/fau/165910
 Subject Headings
 Biomathematics, Biocomplexity, SelfOrganizing systems, Cellular automatamathematical models, Fractals, MoleculesMathematical models
 Format
 Document (PDF)
 Title
 Design and finite element analysis of an ocean current turbine blade.
 Creator
 Asseff, Nicholas S., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

A composite 3 meter ocean current turbine blade has been designed and analyzed using Blade Element Theory (BET) and commercial Finite Element Modeling (FEM) code, ANSYS. It has been observed that using the numerical BET tool created, power production up to 141 kW is possible from a 3 bladed rotor in an ocean current of 2.5 m/s with the proposed blade design. The blade is of sandwich construction with carbon fiber skin and high density foam core. It also contains two webs made of S2glass for...
Show moreA composite 3 meter ocean current turbine blade has been designed and analyzed using Blade Element Theory (BET) and commercial Finite Element Modeling (FEM) code, ANSYS. It has been observed that using the numerical BET tool created, power production up to 141 kW is possible from a 3 bladed rotor in an ocean current of 2.5 m/s with the proposed blade design. The blade is of sandwich construction with carbon fiber skin and high density foam core. It also contains two webs made of S2glass for added shear rigidity. Four design cases were analyzed, involving differences in hydrodynamic shape, material properties, and internal structure. Results from the linear static structural analysis revealed that the best design provides adequate stiffness and strength to produce the proposed power without any structural failure. An Eigenvalue Buckling analysis confirmed that the blade would not fail from buckling prior to overstressed laminate failure if the loading was to exceed the Safety Factor.
Show less  Date Issued
 2009
 PURL
 http://purl.flvc.org/FAU/221944
 Subject Headings
 Marine turbines, Mathematical models, Fluid dynamics, Structural dynamics, Composite materials, Mathematical models
 Format
 Document (PDF)
 Title
 The acoustic far field of a turbulent boundary layer flow calculated from RANS simulations of the flow.
 Creator
 Blanc, JeanBaptiste., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

Boundary layers are regions where turbulence develops easily. In the case where the flow occurs on a surface showing a certain degree of roughness, turbulence eddies will interact with the roughness elements and will produce an acoustic field. This thesis aims at predicting this type of noise with the help of the Computational Fluid Dynamics (CFD) simulation of a wall jet using the Reynolds Average NavierStokes (RANS) equations. A frequency spectrum is reconstructed using a representation of...
Show moreBoundary layers are regions where turbulence develops easily. In the case where the flow occurs on a surface showing a certain degree of roughness, turbulence eddies will interact with the roughness elements and will produce an acoustic field. This thesis aims at predicting this type of noise with the help of the Computational Fluid Dynamics (CFD) simulation of a wall jet using the Reynolds Average NavierStokes (RANS) equations. A frequency spectrum is reconstructed using a representation of the turbulence with uncorrelated sheets of vorticity. Both aerodynamic and acoustic results are compared to experimental measurements of the flow. The CFD simulation of the flow returns consistent results but would benefit from a refinement of the grid. The surface pressure spectrum presents a slope in the high frequencies close to the experimental spectrum. The far field noise spectrum has a 5dB difference to the experiments.
Show less  Date Issued
 2009
 PURL
 http://purl.flvc.org/FAU/368611
 Subject Headings
 Computational fluid dynamics, Turbulence, Mathematical models, Fluid mechanics, Mathematical models, Acoustical engineering
 Format
 Document (PDF)
 Title
 Rapid distortion theory for rotor inflows.
 Creator
 Kawashima, Emilia, Glegg, Stewart A. L., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

For aerospace and naval applications where low radiated noise levels are a requirement, rotor noise generated by inflow turbulence is of great interest. Inflow turbulence is stretched and distorted as it is ingested into a thrusting rotor which can have a significant impact on the noise source levels. This thesis studies the distortion of subsonic, high Reynolds number turbulent flow, with viscous effects ignored, that occur when a rotor is embedded in a turbulent boundary layer. The analysis...
Show moreFor aerospace and naval applications where low radiated noise levels are a requirement, rotor noise generated by inflow turbulence is of great interest. Inflow turbulence is stretched and distorted as it is ingested into a thrusting rotor which can have a significant impact on the noise source levels. This thesis studies the distortion of subsonic, high Reynolds number turbulent flow, with viscous effects ignored, that occur when a rotor is embedded in a turbulent boundary layer. The analysis is based on Rapid Distortion Theory (RDT), which describes the linear evolution of turbulent eddies as they are stretched by a mean flow distortion. Providing that the gust does not distort the mean flow streamlines the solution for a mean flow with shear is found to be the same as the solution for a mean potential flow with the addition of a potential flow gust. By investigating the inflow distortion of smallscale turbulence for various simple flows and rotor inflows with weak shear, it is shown that RDT can be applied to incompressible shear flows to determine the flow distortion. It is also shown that RDT can be applied to more complex flows modeled by the Reynolds Averaged Navier Stokes (RANS) equations.
Show less  Date Issued
 2013
 PURL
 http://purl.flvc.org/fau/fd/FA0004030
 Subject Headings
 Computational fluid dynamics, Fluid dynamic measurements, Fluid mechanics  Mathematical models, Turbulence  Computer simulation, Turbulence  Mathematical models
 Format
 Document (PDF)
 Title
 Reliabilitybased fatigue design of marine current turbine rotor blades.
 Creator
 Hurley, Shaun., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
 Abstract/Description

The study presents a reliabilitybased fatigue life prediction model for the ocean current turbine rotor blades. The numerically simulated bending moment ranges based on the measured current velocities off the Southeast coast line of Florida over a one month period are used to reflect the shortterm distribution of the bending moment ranges for an idealized marine current turbine rotor blade. The 2parameter Weibull distribution is used to fit the shortterm distribution and then used to...
Show moreThe study presents a reliabilitybased fatigue life prediction model for the ocean current turbine rotor blades. The numerically simulated bending moment ranges based on the measured current velocities off the Southeast coast line of Florida over a one month period are used to reflect the shortterm distribution of the bending moment ranges for an idealized marine current turbine rotor blade. The 2parameter Weibull distribution is used to fit the shortterm distribution and then used to obtain the longterm distribution over the design life. The longterm distribution is then used to determine the number of cycles for any given bending moment range. The published laboratory test data in the form of an εN curve is used in conjunction with the longterm distribution of the bending moment ranges in the prediction of the fatigue failure of the rotor blade using Miner's rule. The firstorder reliability method is used in order to determine the reliability index for a given section modulus over a given design life. The results of reliability analysis are then used to calibrate the partial safety factors for load and resistance.
Show less  Date Issued
 2011
 PURL
 http://purl.flvc.org/FAU/3183123
 Subject Headings
 Turbines, Blades, Materials, Fatigue, Marine turbines, Mathematical models, Composite materials, Mathematical models, Structural dynamics
 Format
 Document (PDF)
 Title
 Mathematical modeling of wavecurrent interactions in marine current turbines.
 Creator
 Singh, Amit J., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
 Abstract/Description

The concept of marine current turbines was developed by Peter Fraenkel in the early 1970s. Ever since Fraenkel's efforts to modify and test the technology, several worldwide agencies have been exploiting the technology to retrofit the marine current turbine to their particular application. The marine current turbine has evolved from generating a few kilowatts to a few gigawatts. The present study focuses on a megawatt sized turbine to be located offshore the coast of Ft. Lauderdale, Florida....
Show moreThe concept of marine current turbines was developed by Peter Fraenkel in the early 1970s. Ever since Fraenkel's efforts to modify and test the technology, several worldwide agencies have been exploiting the technology to retrofit the marine current turbine to their particular application. The marine current turbine has evolved from generating a few kilowatts to a few gigawatts. The present study focuses on a megawatt sized turbine to be located offshore the coast of Ft. Lauderdale, Florida. The turbine is to be placed in a similar location as a 20 kW test turbine developed by the Southeast National Marine Renewable Energy Center (SNMREC) at Florida Atlantic University, Dania Beach, FL. Data obtained from the SNMREC is used in the mathematical model. ANSYS FLUENT is chosen as the CFD software to perform wavecurrent interaction simulation for the present study. The turbine is modeled in SolidWorks, then meshed in ANSYS ICEM CFD, then run in FLUENT. The results obtained are compared to published work by scholarly articles from Fraenkel, Barltrop and many other well known marine energy researchers. The effects of wave height on the turbine operation are analyzed and the results are presented in the form of plots for tip speed ratio and current velocity.
Show less  Date Issued
 2012
 PURL
 http://purl.flvc.org/FAU/3352832
 Subject Headings
 Wave resistance (Thermodynamics), Structural design, Mathematical models, Laser Doppler velocimetry, Marine turbines, Mathematical models
 Format
 Document (PDF)
 Title
 Mathematical modeling of plankton patchiness.
 Creator
 Ather, Simantha S., Charles E. Schmidt College of Science, Department of Biological Sciences
 Abstract/Description

In natural systems, it has been observed that plankton exist in patches rather than in an even distribution across a body of water. However, the mechanisms behind this patchiness are not fully understood. Several previous modeling studies have examined the effects of abiotic and biotic factors on patch structure. Yet these models ignore a key point: zooplankton often undergo diel vertical migration. I have formulated a model that incorporates vertical movement into the RosezweigMacArthur (R...
Show moreIn natural systems, it has been observed that plankton exist in patches rather than in an even distribution across a body of water. However, the mechanisms behind this patchiness are not fully understood. Several previous modeling studies have examined the effects of abiotic and biotic factors on patch structure. Yet these models ignore a key point: zooplankton often undergo diel vertical migration. I have formulated a model that incorporates vertical movement into the RosezweigMacArthur (RM) predatorprey model. The RM model is stable only at a carrying capacity below a critical value. I found that adding vertical movement stabilizes the system even at a high carrying capacity. By analyzing temporal stability and spatial structure, my results show that vertical movement interacts with carrying capacity to determine patch structure.
Show less  Date Issued
 2009
 PURL
 http://purl.flvc.org/FAU/368615
 Subject Headings
 Marine plankton, Vertical distribution, Marine ecology, Mathematical models, Macroecology, Mathematical models
 Format
 Document (PDF)