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Title: Characterization of Internal Wave Activity in the Straits of Florida.
Creator: Tarantul Soto, Andrew, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The Gulf Stream current in the Straits is typically dominated by a strong northerly current, associated shear, and eddies. The water column also includes a prominent thermocline and periodically features internal waves centered on the upper or lower edges of the thermocline. Despite numerous previous related studies, there is limited available field data on internal waves in the Straits of Florida. Here, study and analysis of velocity, temperature and conductivity data acquired in the Straits...
Show moreThe Gulf Stream current in the Straits is typically dominated by a strong northerly current, associated shear, and eddies. The water column also includes a prominent thermocline and periodically features internal waves centered on the upper or lower edges of the thermocline. Despite numerous previous related studies, there is limited available field data on internal waves in the Straits of Florida. Here, study and analysis of velocity, temperature and conductivity data acquired in the Straits over a period of time are described, in support of identifying presence of internal waves in the flow. A systematic procedure is employed in modifying the universal Garrett- Munk spectrum for internal waves in the open ocean for application to flow in the Straits of Florida. Using this process, identified internal waves are characterized and related velocity fluctuations in the time series are isolated to facilitate consideration of their correlations with simultaneously observed magnetic fields.
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Date Issued: 2017
PURL: http://purl.flvc.org/fau/fd/FA00005946
Subject Headings: Dissertations, Academic -- Florida Atlantic University, Florida, Straits of, Gulf Stream (Fla.), Internal waves.
Format: Document (PDF)

Title: Combined spatial diversity and time equalization for broadband multiple channel underwater acoustic communications.
Creator: Skoro Kaskarovska, Violeta, Beaujean, Pierre-Philippe, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: High data rate acoustic communications become feasible with the use of communication systems that operate at high frequency. The high frequency acoustic transmission in shallow water endures severe distortion as a result of the extensive intersymbol interference and Doppler shift, caused by the time variable multipath nature of the channel. In this research a Single Input Multiple Output (SIMO) acoustic communication system is developed to improve the reliability of the high data rate...
Show moreHigh data rate acoustic communications become feasible with the use of communication systems that operate at high frequency. The high frequency acoustic transmission in shallow water endures severe distortion as a result of the extensive intersymbol interference and Doppler shift, caused by the time variable multipath nature of the channel. In this research a Single Input Multiple Output (SIMO) acoustic communication system is developed to improve the reliability of the high data rate communications at short range in the shallow water acoustic channel. The proposed SIMO communication system operates at very high frequency and combines spatial diversity and decision feedback equalizer in a multilevel adaptive configuration. The first configuration performs selective combining on the equalized signals from multiple receivers and generates quality feedback parameter for the next level of combining.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004411, http://purl.flvc.org/fau/fd/FA00004411
Subject Headings: Adaptive signal processing, MIMO systems, Mobile geographic information systems, Signal processing -- Digital techniques, Underwater acoustic telemetry, Underwater acoustics -- Evaluation, Wireless communication systems
Format: Document (PDF)

Title: CFD Study of Pectoral Fins of Larval Zebrafish: Effect of Reynolds Number, Swimming Kinematics and Fin Bending on Fluid Structures and Transport.
Creator: Islam, Toukir, Curet, Oscar M., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Flow Structure and fluid transport via advection around pectoral fin of larval ZebraFish are studied numerically using Immersed Boundary Method, Lagrangian Coherent Structure, passive particle tracing, vortex core evolution and four statistically defined mixing numbers. Experimental fish kinematics for nominal swimming case are obtained from previous researchers and numerically manipulated to analyze the role of different body motion kinematics, Reynolds number and fin morphology on flow...
Show moreFlow Structure and fluid transport via advection around pectoral fin of larval ZebraFish are studied numerically using Immersed Boundary Method, Lagrangian Coherent Structure, passive particle tracing, vortex core evolution and four statistically defined mixing numbers. Experimental fish kinematics for nominal swimming case are obtained from previous researchers and numerically manipulated to analyze the role of different body motion kinematics, Reynolds number and fin morphology on flow structure and transport. Hyperbolic strain field and vortex cores are found to be effective particle transporter and their relative strength are driving force of varying flow structure and fluid transport. Translation and lateral undulation of fish; as a combination or individual entity, has coherent advantages and drawbacks significant enough to alter the nature of fluid advection. Reynolds number increase enhances overall fluid transport and mixing in varying order for different kinematics and nominal bending position of fin has average transport capability of other artificially induced fin morphology.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004606, http://purl.flvc.org/fau/fd/FA00004606
Subject Headings: Reynolds number., Aquatic animals (Physiology), Transport theory., Computational fluid dynamics., Dynamical systems., Continuum physics., Turbulence--Mathematical models.
Format: Document (PDF)

Title: Evaluation of Chloride Threshold for Steel Fiber Reinforced Concrete Composited in Aggressively Corrosive Environments.
Creator: Vogel, Dietrich H., Presuel-Moreno, Francisco, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Highway drainage pipes utilize concrete reinforced with steel wire to help mitigate water, earth, and traffic loads. Drainage pipes reinforced with zinc electroplated steel fibers offer a lower steel alternative to traditional steel wire cage reinforcements. The objective of the thesis research was to determine the physical and electrochemical characteristics of zinc electroplated steel fiber corrosion propagation. Experimental programs include: Fracture analysis of zinc electroplated steel...
Show moreHighway drainage pipes utilize concrete reinforced with steel wire to help mitigate water, earth, and traffic loads. Drainage pipes reinforced with zinc electroplated steel fibers offer a lower steel alternative to traditional steel wire cage reinforcements. The objective of the thesis research was to determine the physical and electrochemical characteristics of zinc electroplated steel fiber corrosion propagation. Experimental programs include: Fracture analysis of zinc electroplated steel fibers embedded in dry-cast concrete pipes exposed to varying chloride concentrations; Visual analysis of zinc electroplated steel fibers embedded in concrete exposed to varying chloride concentrations; Electrochemical analysis of zinc electroplated steel fibers embedded in concrete exposed to varying chlorides; Chloride threshold determination for zinc electroplated steel fibers immersed in simulated pore solution. Between the four experimental programs the most significant conclusion is that oxygen, moisture, and chlorides past the chloride threshold must be present for corrosion to propagate significantly on the zinc electroplated steel fibers.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004637, http://purl.flvc.org/fau/fd/FA00004637
Subject Headings: Fiber-reinforced concrete--Cracking., Cement composites., Reinforced concrete construction., Reinforced concrete--Corrosion., Corrosion and anti-corrosives., Structural engineering.
Format: Document (PDF)

Title: Evaluation of Non-Contact ACL and MCL Strain on Lower Extremities Using a Hybrid Cadaveric System Simulating High Impact Athletic Activates.
Creator: DiRoma, Mark, Hashemi, Javad, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: In this thesis, adaptations were made on the Hybrid Cadaveric System to accommodate new testing ramifications. The tests simulated dynamic loading (jump landings) from a 1ft. height with various degrees of valgus (fixed hamstring and quadricep forces) and various Quadricep (Q) and Hamstring (H) forces (fixed degrees of valgus) to determine how the Anterior Cruciate Ligament (ACL) and Medial Collateral Ligament (MCL) behave. The tests performed included 0Q 0H, 100Q 0H, 300Q 0H, 300Q 100H, and...
Show moreIn this thesis, adaptations were made on the Hybrid Cadaveric System to accommodate new testing ramifications. The tests simulated dynamic loading (jump landings) from a 1ft. height with various degrees of valgus (fixed hamstring and quadricep forces) and various Quadricep (Q) and Hamstring (H) forces (fixed degrees of valgus) to determine how the Anterior Cruciate Ligament (ACL) and Medial Collateral Ligament (MCL) behave. The tests performed included 0Q 0H, 100Q 0H, 300Q 0H, 300Q 100H, and 5°, 15°, 25° of valgus. To determine the strain behavior of the ACL and MCL a variety of equipment was used, including electromagnetic force plate to take impact reading, cables used to create loading on the quadriceps and hamstrings, and two Differential Variance Resistance Transducers (DVRTs). These ultimately generated ACL and MCL strain allowing for a variety of strain comparisons under various circumstances. It was concluded that in a few cases there were statistically significant differences in strain for the ACL and MCL when applying various quadricep and hamstring forces (fixed valgus). It was also found that only statistical significance was present in ACL strain when comparing degrees of valgus (fixed quadricep and hamstring forces). The research concluded that muscle activation reduces strain on the ACL and MCL in these testing scenarios. It was also established that degrees of valgus effects the ACL but is negligible for the MCL. However, due to complications and variables, further testing is needed to increase accuracy and supply more definitive results.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013058
Subject Headings: Anterior Cruciate Ligament., Ligaments--injuries., Athletic Injuries.
Format: Document (PDF)

Title: Empirical Analysis of the Dissipated Acoustic Energy in Wave Breaking.
Creator: Francke, Kristina, Dhanak, Manhar, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description: In this research an attempt is made at explaining the physical processes behind energy dissipation during wave breaking, through spectral analysis of the resulting sound. The size of an air bubble can be directly linked to the frequency of the sound that is heard using the simple harmonic solution to the Rayleigh–Plesset equation. It indicates the inverse relationship between frequency and bubble size. And this relationship has been used to identify wave breaking in general [MANASSEH 2006]....
Show moreIn this research an attempt is made at explaining the physical processes behind energy dissipation during wave breaking, through spectral analysis of the resulting sound. The size of an air bubble can be directly linked to the frequency of the sound that is heard using the simple harmonic solution to the Rayleigh–Plesset equation. It indicates the inverse relationship between frequency and bubble size. And this relationship has been used to identify wave breaking in general [MANASSEH 2006]. Now this research goes a step farther and looks at how the frequency spectrum of the sound changes with time, in an effort to understand the general pattern and from that to deduce an empirical equation that describes the breaking down of turbulence during a wave breaking event. Two main processes have been identified, with the second process having three main indicators that are necessary to evidence wave breaking. The first process is a near instantaneous shattering of the initial air bubble into much smaller metastable bubbles of a size that appears to be common for all waves independent of wave height. Then in the second process, the bubbles continue to break down following a recognisable pattern.
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Date Issued: 2020
PURL: http://purl.flvc.org/fau/fd/FA00013504
Subject Headings: Waves, Energy dissipation, Spectral analysis, Fluid dynamics, Acoustic energy
Format: Document (PDF)

Title: Experiments for Waves Breaking Over a Three-Dimensional Submerged Bar.
Creator: Roy, Travis L., Seiffert, Betsy, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The influence of monochromatic waves interacting with a submerged bar structure is investigated through laboratory experiments in a wave flume. Wave profiles for a range of non-breaking, spilling, and plunging waves were analyzed for three offshore water depths through the interpretation of wave gauge and video imagery data. Evolution of propagating waves was reflected in data which showed increased amplitudes due to shoaling with subsequent breaking, transfer of single frequency spectrum...
Show moreThe influence of monochromatic waves interacting with a submerged bar structure is investigated through laboratory experiments in a wave flume. Wave profiles for a range of non-breaking, spilling, and plunging waves were analyzed for three offshore water depths through the interpretation of wave gauge and video imagery data. Evolution of propagating waves was reflected in data which showed increased amplitudes due to shoaling with subsequent breaking, transfer of single frequency spectrum from lower to higher frequency harmonics, and dissipation of energy after breaking onset. Comparisons of collected experimental data with previous theory developed by Yao et al (2013), Smith & Kraus (1991), Galvin (1968) for wave classification showed to be relatively accurate for both relative submergence and surf similarity methods. Wave breaking onset identified by instability in the wave crests allowed for measurements of breaking wave height and depth at breaking. Theory by Johnson (2006) and Goda (1974) compared to experimental data showed little agreement for predicting breaking wave heights.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013096
Subject Headings: Water waves., Water waves--Measurement., Surface waves.
Format: Document (PDF)

Title: Experimental analysis of the effect of waves on a floating wind turbine.
Creator: Isaza, Francisco, Ghenai, Chaouki, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The goal of this Thesis is to demonstrate, through experimentation, that ocean waves have a positive effect on the performance of an offshore wind turbine. A scale model wind turbine was placed into a wave tank that was completely covered and fitted with a variable speed fan to create different wind and wave conditions for testing. Through testing, different power coefficient vs. tip speed ratio graphs were created and a change in power coefficient was observed between steady operating...
Show moreThe goal of this Thesis is to demonstrate, through experimentation, that ocean waves have a positive effect on the performance of an offshore wind turbine. A scale model wind turbine was placed into a wave tank that was completely covered and fitted with a variable speed fan to create different wind and wave conditions for testing. Through testing, different power coefficient vs. tip speed ratio graphs were created and a change in power coefficient was observed between steady operating conditions and operating conditions with waves. The results show a promising increase in power production for offshore wind turbines when allowed to operate with the induced motion caused by the amplitude and frequency of water waves created.
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Date Issued: 2013
PURL: http://purl.flvc.org/fau/fd/FA0004026
Subject Headings: Fluid mechanics, Offshore wind power plants, Renewable energy sources, Wind turbines -- Design and construction
Format: Document (PDF)

Title: FACE/CORE DISBONDING FRACTURE OF HONEYCOMB CORE SANDWICH PANELS.
Creator: Tauhiduzzaman, Mohammad, Carlsson, Leif A., Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description: The objective of the research presented in this thesis is to develop analysis and test procedures for the characterization of disbonding crack growth in a honeycomb (HC) core sandwich structure. Face sheet-to-core disbonding are of particular interest to aircraft certification authorities due to several in-service occurrences. Experimental investigation was initially focused on the mode I dominated Single Cantilever Beam (SCB) test method. Various data reduction methodologies were employed to...
Show moreThe objective of the research presented in this thesis is to develop analysis and test procedures for the characterization of disbonding crack growth in a honeycomb (HC) core sandwich structure. Face sheet-to-core disbonding are of particular interest to aircraft certification authorities due to several in-service occurrences. Experimental investigation was initially focused on the mode I dominated Single Cantilever Beam (SCB) test method. Various data reduction methodologies were employed to determine the fracture toughness. The MBT method produced the most consistent and conservative results. Finite element analysis (FEA) a double periodic array of hexagonal cells was conducted to determine the effective in-plane extensional modulus and Poisson ratio of the HC core. It was shown that deformation constraints on the core, due to attachment of the core to rigid face sheets, will drastically change the behavior of the HC core. The response changes from being governed by bending to stretching which substantially elevates the effective in-plane modulus. Fracture mechanics analysis of a face/core interface crack in a HC core SCB specimen was performed using FEA. The influence of in-plane properties of the constrained core on energy release rate and mode mixity phase angle was examined. Use of plane strain conditions and an elevated modulus of the constrained core in the analysis is recommended. The approach is substantiated by testing of HC core SCB sandwich. Test results showed good agreement with FEA prediction of compliance and kink angle.
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Date Issued: 2019
PURL: http://purl.flvc.org/fau/fd/FA00013419
Subject Headings: Honeycomb structures, Fracture mechanics, Strength of materials, Airframes--Materials
Format: Document (PDF)

Title: ENGINEERING CHANNELS IN POROUS CALCIUM PHOSPHATE BIOCERAMIC SCAFFOLDS FOR BONE TISSUE REGENERATION.
Creator: Wang, Xuesong, Kang, Yunqing, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description: Inadequate nutrition exchange and slow transportation in a porous scaffold often resulted in insufficient vasculature formation, which hindered rapid bone regeneration. In this study, interconnected porous beta-tricalcium phosphate (b-TCP) scaffolds with channeled geometry were fabricated. In vitro fluid transportation and degradation of the scaffolds were performed. Cell attachment, migration, proliferation, and differentiation were carried out under both static and dynamic culturing...
Show moreInadequate nutrition exchange and slow transportation in a porous scaffold often resulted in insufficient vasculature formation, which hindered rapid bone regeneration. In this study, interconnected porous beta-tricalcium phosphate (b-TCP) scaffolds with channeled geometry were fabricated. In vitro fluid transportation and degradation of the scaffolds were performed. Cell attachment, migration, proliferation, and differentiation were carried out under both static and dynamic culturing conditions. A computational simulation model and a series of immunofluorescent staining were implemented to understand the mechanism of cell behavior in respond to different scaffolds geometry. We then implanted scaffolds into rat critical-sized calvarial defects to further evaluate channels’ function on bone regeneration in vivo. Results showed that multiple channeled geometry significantly accelerated the release of Ca2+ and increased the fluid diffusion efficiency. Moreover, multiple channels promoted human umbilical vein endothelial cells (HUVECs) infiltration, migration, besides prominently promoted alkaline phosphatase (ALP) activity, and up-regulated osteogenic gene expression in human bone marrow mesenchymal stem cells (hBMSCs) at both static and dynamic culturing conditions in vitro. The expression of both cell migration related protein a5 and angiogenesis related protein CD31 were upregulated by multiple channels in HUVECs. And the expression of mechanosensing markers, focal adhesion kinase (FAK), polymeric filamentous actin (Factin), and Yes-associated protein-1 (YAP-1) were highly stimulated by multiple channels in hBMSCs. The in vivo implantation and characterization results demonstrated more bone formation inside multiple-channeled scaffolds compared to non-channeled scaffolds. Multiple channels accelerated collagen type I, Bone Sialoprotein (Bsp), Osteocalcin (OC) protein expression prominently. The angiogenesis related protein CD31 staining displayed longer and more vasculature structures on multiple-channeled scaffolds compared to nonchanneled scaffolds. Fluorescent images of the fluorochrome labeled samples exhibited considerably more mineral deposition on multiple-channeled scaffolds than non-channeled scaffolds. All the findings suggested that the addition of multiple channels in the porous b-TCP scaffold is very promising approach to promote vascularization and bone tissue regeneration.
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Date Issued: 2019
PURL: http://purl.flvc.org/fau/fd/FA00013426
Subject Headings: Tissue Engineering, Bone and Bones, Bone regeneration, Calcium Phosphates, Biocompatible Materials
Format: Document (PDF)

Title: Electromagnetic field emissions from underwater power cables.
Creator: DiBiasio, Christopher, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This study is performed as a partial aid to a larger study that aims to determine if electromagnetic fields produced by underwater power cables have any effect on marine species. In this study, a new numerical method for calculating magnetic fields around subsea power cables is presented and tested. The numerical method is derived from electromagnetic theory, and the program, Matlab, is implemented in order to run the simulations. The Matlab code is validated by performing a series of tests...
Show moreThis study is performed as a partial aid to a larger study that aims to determine if electromagnetic fields produced by underwater power cables have any effect on marine species. In this study, a new numerical method for calculating magnetic fields around subsea power cables is presented and tested. The numerical method is derived from electromagnetic theory, and the program, Matlab, is implemented in order to run the simulations. The Matlab code is validated by performing a series of tests in which the theoretical code is compared with other previously validated magnetic field solvers. Three main tests are carried out; two of these tests are physical and involve the use of a magnetometer, and the third is numerical and compares the code with another numerical model known as Ansys. The data produced by the Matlab code remains consistent with the measured values from both the magnetometer and the Ansys program; thus, the code is considered valid. The validated Matlab code can then be implemented into other parts of the study in order to plot the magnetic field around a specific power cable.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004277, http://purl.flvc.org/fau/fd/FA00004277
Subject Headings: DIstributed generation of electric power, Electromagnetic interference, Electromagnetic theory, Ocean energy resources -- Environmental aspects
Format: Document (PDF)

Title: Computational Study of the Heat Transfer and Fluid Structure of a Shell and Tube Heat Exchanger.
Creator: Betancourt, Arturo, Curet, Oscar M., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A common technique to improve the performance of shell and tube heat exchangers (STHE) is by redirecting the flow in the shell side with a series of baffles. A key aspect in this technique is to understand the interaction of the fluid dynamics and heat transfer. Computational fluid dynamics simulations and experiments were performed to analysis the 3-dimensional flow and heat transfer on the shell side of an STHE with and without baffles. Although, it was found that there was a small...
Show moreA common technique to improve the performance of shell and tube heat exchangers (STHE) is by redirecting the flow in the shell side with a series of baffles. A key aspect in this technique is to understand the interaction of the fluid dynamics and heat transfer. Computational fluid dynamics simulations and experiments were performed to analysis the 3-dimensional flow and heat transfer on the shell side of an STHE with and without baffles. Although, it was found that there was a small difference in the average exit temperature between the two cases, the heat transfer coefficient was locally enhanced in the baffled case due to flow structures. The flow in the unbaffled case was highly streamed, while for the baffled case the flow was a highly complex flow with vortex structures formed by the tip of the baffles, the tubes, and the interaction of flow with the shell wall.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004569, http://purl.flvc.org/fau/fd/FA00004569
Subject Headings: Computational fluid dynamics., Thermodynamics., Heat exchangers--Design and construction., Heat--Transmission--Computer programs.
Format: Document (PDF)

Title: Corrosion Propagation of Reinforcing Steel Embedded in Binary and Ternary Concrete.
Creator: Hoque, Kazi Naimul, Presuel-Moreno, Francisco, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description: The Florida Department of Transportation (FDOT) has been using supplementary cementitious materials while constructing steel reinforced concrete marine bridge structures for over three decades. It has been found from previous studies that such additions in concrete mix makes the concrete more durable. This research was conducted to better understand the corrosion propagation stage of steel rebar embedded in high performance concrete exposed to high humidity environment. Reinforced concrete...
Show moreThe Florida Department of Transportation (FDOT) has been using supplementary cementitious materials while constructing steel reinforced concrete marine bridge structures for over three decades. It has been found from previous studies that such additions in concrete mix makes the concrete more durable. This research was conducted to better understand the corrosion propagation stage of steel rebar embedded in high performance concrete exposed to high humidity environment. Reinforced concrete samples that were made with binary mixes, and ternary mixes were considered. None of these concretes had any admixed chloride to start with. An accelerated chloride transport method was used to drive chloride ions into the concrete so that chlorides reached and exceed the chloride threshold at the rebar surface and hence the corrosion process initiated after a short period of time (within few days to few months). Once corrosion has initiated the corrosion propagation can be studied. Electrochemical measurements such as rebar potential measurements, Linear Polarization Resistance (LPR), Electrochemical Impedance Spectroscopy (EIS), and Galvanostatic Pulse (GP) measurements were taken at regular intervals (during and after the electro-migration process) to observe the corrosion propagation in each sample. During the propagation stage, reinforcement eventually reached negative potentials values (i.e., Ecorr≤ –0.200 Vsce) for all the samples. The corrected polarization resistance (Rc) was calculated by subtracting the concrete solution resistance from the apparent polarization resistance measured. The Rc values obtained from LPR and GP measurements were converted to corrosion current (as the corroding area is unknown), and these corrosion current values measured over time were used to obtain the calculated mass loss (using Faraday’s Law). A comparison was made of the calculated corrosion current obtained using the LPR and GP tests. A comparison of mass loss was also obtained from the values measured from LPR and GP tests. From the experimental results, it was observed that the corrosion current values were largely dependent on the length of solution reservoirs. For specimens cast with single rebar as well as three rebars, the most recent corrosion current values (measurements taken between July 2018 to October 2020) in general were larger for the rebars that are embedded in specimens prepared with SL mix, followed by specimens prepared with FA, T1, and T2 mixes respectively. The range of corrosion current values (most recent) were 0.8-33.8 μA for SL samples, 0.5-22.5 μA for FA samples, 0.8-14.8 μA for T1 samples, and 0.7-10.4 μA for T2 samples respectively. It was also found that the calculated mass loss values were larger for rebars that are embedded in specimens (single rebar and three rebars) prepared with SL mix, followed by specimens prepared with FA, T1, and T2 mixes respectively. The range of calculated mass loss values were 0.07-1.13 grams for SL samples, 0.06-0.62 grams for FA samples, 0.12-0.54 grams for T1 samples, and 0.06-0.40 grams for T2 samples respectively. A variety of corrosion related parameters (Ecorr, Rs, Rc, and Icorr) and calculated theoretical mass loss values observed, were due to the changing parameters such as concrete compositions, concrete cover thickness, rebar diameter, total ampere-hour applied, and reservoir size. The specimens showed no visual signs of corrosion such as cracks or corrosion products that reached the concrete surface. The actual size of the corroding sites was unknown as the specimens were not terminated for forensic analysis. The size of the corroding sites could affect how much corrosion products are required to crack the concrete. It is speculated that the corrosion products in liquid form penetrated the pore structure but did not build up enough to cause cracks. No cracks or corrosion bleed outs were observed within the monitored propagation period of approximately 1600 days.
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Date Issued: 2020
PURL: http://purl.flvc.org/fau/fd/FA00013634
Subject Headings: Concrete, Concrete bridges--Corrosion, Carbon steel
Format: Document (PDF)

Title: DEVELOPMENT OF AN ELASTIC POLYMER-BASED DRUG DELIVERY SYSTEM FOR TISSUE REGENERATION.
Creator: Firoozi, Negar, Kang, Yunqing, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: In spite of the vast research on polymer-based tissue regeneration, extensive studies to develop an elastic and cell-promoting polymer biomaterial are still ongoing. However, using a renewable resource and a simple, environment-friendly synthesis route to synthesize an elastic polymer has not been successfully achieved yet. The objective of this work was to develop an elastic polymer for tissue engineering and drug delivery applications by using non-toxic, inexpensive and renewable monomers....
Show moreIn spite of the vast research on polymer-based tissue regeneration, extensive studies to develop an elastic and cell-promoting polymer biomaterial are still ongoing. However, using a renewable resource and a simple, environment-friendly synthesis route to synthesize an elastic polymer has not been successfully achieved yet. The objective of this work was to develop an elastic polymer for tissue engineering and drug delivery applications by using non-toxic, inexpensive and renewable monomers. A new nature-derived renewable material, xylitol, was used to synthesize an elastic polymer with the presence of a crosslinking agent, dodecanedioic acid. Here a simple melt condensation polymerization method was used to synthesize the poly(xylitoldodecanedioic acid)(PXDDA). The physicochemical and biological properties of the new PXDDA polymer were characterized. Fourier transform infrared (FTIR) confirmed the formation of ester bonding in the polymer structure, and thermal analysis demonstrated that the polymer was completely amorphous. The polymer shows high elasticity. Increasing the molar ratio of dodecanedioic acid resulted in higher hydrophobicity and lower glass transition temperature. Further, the polymer degradation and in vitro dye release studies revealed that the degradation and dye release from the polymer became slower when the amount of dodecanedioic acid in the composite increased.
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Date Issued: 2019
PURL: http://purl.flvc.org/fau/fd/FA00013306
Subject Headings: Drug Delivery Systems, Polymers, Tissue Engineering, Xylitol
Format: Document (PDF)

Title: Chloride penetration into concrete structures exposed to the marine atmosphere.
Creator: Shill, Scott Thompson, Presuel-Moreno, Francisco, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Chloride ions present in the marine atmosphere contained in marine aerosols is investigated for a relationship with chloride that accumulated into concrete. Chloride profiles are conducted on several concrete mixes containing fly ash, silica fume, and slag, with water to cementitious ratios of 0.35, 0.41, and 0.47. The chloride accumulation in concrete samples exposed to the environment is investigated with relation to the chloride deposition from the marine atmosphere measured via the wet...
Show moreChloride ions present in the marine atmosphere contained in marine aerosols is investigated for a relationship with chloride that accumulated into concrete. Chloride profiles are conducted on several concrete mixes containing fly ash, silica fume, and slag, with water to cementitious ratios of 0.35, 0.41, and 0.47. The chloride accumulation in concrete samples exposed to the environment is investigated with relation to the chloride deposition from the marine atmosphere measured via the wet candle test. Results indicate a possible relationship for the total accumulated chloride in the concrete with the accumulated chloride deposition (wet candle). Over the exposure periods, concrete specimens with 50% slag addition and 0.47 w/cm had the lowest average rates of chloride accumulation for deposition under 100 g/m2day. Chloride accumulation was lower in concrete containing 20% fly ash and 8% silica fume with 0.35 w/cm for chloride deposition rates over 200 g/m2day.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004227, http://purl.flvc.org/fau/fd/FA00004227
Subject Headings: Chlorides -- Diffusion rate, Chlorides -- Environmental aspects, Concrete -- Chemical resistance, Concrete -- Permeability, Reinforced concrete -- Construction -- Corrosion
Format: Document (PDF)

Title: Chloride Diffusivity and Aging Factor Determined on Field Simulated Concrete Exposed to Seawater.
Creator: Raof, Farhad Fakheri, Presuel-Moreno, Francisco, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Chloride diffusivity in high performance concrete is influenced by the exposure environment, aside from the concrete mixture properties like, water to cementitious ratio (w/cm) and presence of add-on pozzolans. In this study, a set of concrete specimens (eleven-different concrete mixtures) were cast and exposed to three different environmental conditions (Tidal, Splash and Barge) in which the solution was seawater or brackish water. These exposures simulated environmental field conditions....
Show moreChloride diffusivity in high performance concrete is influenced by the exposure environment, aside from the concrete mixture properties like, water to cementitious ratio (w/cm) and presence of add-on pozzolans. In this study, a set of concrete specimens (eleven-different concrete mixtures) were cast and exposed to three different environmental conditions (Tidal, Splash and Barge) in which the solution was seawater or brackish water. These exposures simulated environmental field conditions. After the specimens had been wet cured for 32 days (on average), the specimens were exposed to three different field simulation conditions for up to 54 months. The specimens under the field simulated conditions were cored at 6, 10, 18, 30 and 54 months at four elevations and then the chloride profiles were obtained from the cores. The apparent diffusivity values for each profile were calculated based on Fick’s 2nd law. Then, the aging factor “m” was calculated by regression analysis of the diffusivity values vs. time (days) plotted in the log10-log10 scale. This was done for samples exposed to the three different exposure conditions and then the results were compared side-by-side. First, the “m” values were calculated using the exposure duration. Then, to study the effect of including the curing time on “m” value, the curing time was added to the exposure time and a new calculation and “m” value was obtained and compared with the previous results. Moreover, upon inspecting the chloride diffusivity values vs. time plots, it was observed that in some cases, a number of data points showed significantly higher or lower values in comparison with the rest of the data points. It was decided to recalculate the “m” values for these cases, and to only use selected data points instead of all data points (i.e., remove outlier data points). In terms of chloride diffusivity value, it was found that in most cases the specimens with higher water to cementitious (w/cm) ratio showed higher diffusivity, as expected. Further, the presence of pozzolans had a noticeable impact on the chloride diffusivity by decreasing the diffusion rate due to microstructure changes that occurred with time. In terms of “m” values, the result for the field simulated conditions showed a range of “m” values dependent on the specimen’s mixture composition and the elevation at which the specimens were cored. It was observed that the chloride diffusivity declined with time and after a certain amount of time (in this research, almost after 30 months) the diffusivity reduction became small and a transition in the slope of the diffusivity trend appeared in a number of cases. After the transition, the diffusivity trend reached either a plateau zone or continued with a significantly lower slope, depending on the time, composition and exposure. It was found that the specimens under tidal and splash field simulation conditions that had only fly ash in their mixtures showed higher “m” values when compared with samples that contained fly ash and silica fume or fifty percent slag.
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Date Issued: 2019
PURL: http://purl.flvc.org/fau/fd/FA00013254
Subject Headings: Concrete--Environmental testing, Seawater, Chlorides, Diffusion, Concrete--Deterioration
Format: Document (PDF)

Title: Corrosion Propagation of Rebar Embedded in High Performance Concrete.
Creator: Nazim, Manzurul, Presuel-Moreno, Francisco, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The FDOT has been using supplementary cementitious materials while constructing steel reinforced concrete marine bridge structures for over 3 decades. Previous findings indicated that such additions in concrete mix makes the concrete more durable. To better understand corrosion propagation of rebar in high performance concrete: mature concrete samples that were made (2008/2009) with Portland cement, a binary mix, a ternary mix and recently prepared (April 2016 with 50% OPC + 50% slag and 80%...
Show moreThe FDOT has been using supplementary cementitious materials while constructing steel reinforced concrete marine bridge structures for over 3 decades. Previous findings indicated that such additions in concrete mix makes the concrete more durable. To better understand corrosion propagation of rebar in high performance concrete: mature concrete samples that were made (2008/2009) with Portland cement, a binary mix, a ternary mix and recently prepared (April 2016 with 50% OPC + 50% slag and 80% OPC + 20% Fly ash) concrete samples were considered. None of these concretes had any admixed chloride to start with. An accelerated chloride transport process was used to drive chloride ions into the concrete so that chlorides reach and exceed thechloride threshold at the rebar surface and initiate corrosion. Electrochemical measurements were taken at regular intervals (during and after the electro-migration process) to observe the corrosion propagation in each sample.
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Date Issued: 2017
PURL: http://purl.flvc.org/fau/fd/FA00004941, http://purl.flvc.org/fau/fd/FA00004941
Subject Headings: Reinforced concrete--Corrosion., Reinforced concrete--Chemical resistance., Reinforced concrete--Deterioration., Concrete--Corrosion., Concrete--Mechanical properties.
Format: Document (PDF)

Title: Dynamics and Control of Autonomous Underwater Vehicles with Internal Actuators.
Creator: Li, Bo, Su, Tsung-Chow, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This dissertation concerns the dynamics and control of an autonomous underwater vehicle (AUV) which uses internal actuators to stabilize its horizontalplane motion. The demand for high-performance AUVs are growing in the field of ocean engineering due to increasing activities in ocean exploration and research. New generations of AUVs are expected to operate in harsh and complex ocean environments. We propose a hybrid design of an underwater vehicle which uses internal actuators instead of...
Show moreThis dissertation concerns the dynamics and control of an autonomous underwater vehicle (AUV) which uses internal actuators to stabilize its horizontalplane motion. The demand for high-performance AUVs are growing in the field of ocean engineering due to increasing activities in ocean exploration and research. New generations of AUVs are expected to operate in harsh and complex ocean environments. We propose a hybrid design of an underwater vehicle which uses internal actuators instead of control surfaces to steer. When operating at low speeds or in relatively strong ocean currents, the performances of control surfaces will degrade. Internal actuators work independent of the relative ows, thus improving the maneuvering performance of the vehicle. We develop the mathematical model which describes the motion of an underwater vehicle in ocean currents from first principles. The equations of motion of a body-fluid dynamical system in an ideal fluid are derived using both Newton-Euler and Lagrangian formulations. The viscous effects of a real fluid are considered separately. We use a REMUS 100 AUV as the research model, and conduct CFD simulations to compute the viscous hydrodynamic coe cients with ANSYS Fluent. The simulation results show that the horizontal-plane motion of the vehicle is inherently unstable. The yaw moment exerted by the relative flow is destabilizing. The open-loop stabilities of the horizontal-plane motion of the vehicle in both ideal and real fluid are analyzed. In particular, the effects of a roll torque and a moving mass on the horizontal-plane motion are studied. The results illustrate that both the position and number of equilibrium points of the dynamical system are prone to the magnitude of the roll torque and the lateral position of the moving mass. We propose the design of using an internal moving mass to stabilize the horizontal-plane motion of the REMUS 100 AUV. A linear quadratic regulator (LQR) is designed to take advantage of both the linear momentum and lateral position of the internal moving mass to stabilize the heading angle of the vehicle. Alternatively, we introduce a tunnel thruster to the design, and use backstepping and Lyapunov redesign techniques to derive a nonlinear feedback control law to achieve autopilot. The coupling e ects between the closed-loop horizontal-plane and vertical-plane motions are also analyzed.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004738, http://purl.flvc.org/fau/fd/FA00004738
Subject Headings: Dynamics., Remote submersibles--Design and construction., Ocean engineering., Fluid dynamics., Nonlinear control theory., Differentiable dynamical systems.
Format: Document (PDF)

Title: Developing interpretive turbulence models from a database with applications to wind farms and shipboard operations.
Creator: Schau, Kyle A., Gaonkar, Gopal H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This thesis presents a complete method of modeling the autospectra of turbulence in closed form via an expansion series using the von Kármán model as a basis function. It is capable of modeling turbulence in all three directions of fluid flow: longitudinal, lateral, and vertical, separately, thus eliminating the assumption of homogeneous, isotropic flow. A thorough investigation into the expansion series is presented, with the strengths and weaknesses highlighted. Furthermore, numerical...
Show moreThis thesis presents a complete method of modeling the autospectra of turbulence in closed form via an expansion series using the von Kármán model as a basis function. It is capable of modeling turbulence in all three directions of fluid flow: longitudinal, lateral, and vertical, separately, thus eliminating the assumption of homogeneous, isotropic flow. A thorough investigation into the expansion series is presented, with the strengths and weaknesses highlighted. Furthermore, numerical aspects and theoretical derivations are provided. This method is then tested against three highly complex flow fields: wake turbulence inside wind farms, helicopter downwash, and helicopter downwash coupled with turbulence shed from a ship superstructure. These applications demonstrate that this method is remarkably robust, that the developed autospectral models are virtually tailored to the design of white noise driven shaping filters, and that these models in closed form facilitate a greater understanding of complex flow fields in wind engineering.
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Date Issued: 2013
PURL: http://purl.flvc.org/fau/fd/FA0004058
Subject Headings: Fluid mechanics, Renewable energy sources, Von Kármán, Theodore -- 1881-1963, Wind energy conservation systems, Wind power, Wind turbines -- Aerodynamics
Format: Document (PDF)

Title: Development of MnO2 Hollow Nanoparticles for Drug Delivery.
Creator: Greene, Allison, Kang, Yunqing, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description: This thesis reports the development of a novel drug delivery system consisting of hollow nanoparticles, formed from manganese dioxide (δ-MnO2) sheets, that are coated with polydopamine and folic acid to selectively target cancer cells. The biodegradability and colloidal stability of the uncoated hollow nanoparticles were investigated in comparison to solid MnO2 nanoparticles and graphene oxide sheets. The MnO2 hollow nanoparticles degraded at a faster rate and seem to have a higher surface...
Show moreThis thesis reports the development of a novel drug delivery system consisting of hollow nanoparticles, formed from manganese dioxide (δ-MnO2) sheets, that are coated with polydopamine and folic acid to selectively target cancer cells. The biodegradability and colloidal stability of the uncoated hollow nanoparticles were investigated in comparison to solid MnO2 nanoparticles and graphene oxide sheets. The MnO2 hollow nanoparticles degraded at a faster rate and seem to have a higher surface area and better colloidal dispersion than solid MnO2 nanoparticles. Xanthan gum was proven to improve colloidal dispersion of these hollow nanoparticles and were used for further cell studies. In this study, cancer and healthy cells were treated with coated hollow nanoparticles, and results indicate that this novel hollow nanoparticle may preferentially target and kill cancer cells. Particle aggregation has shown to be toxic to cells. Further studies with this novel drug delivery system may lead to a groundbreaking solution to targeted cancer therapy.
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Date Issued: 2020
PURL: http://purl.flvc.org/fau/fd/FA00013513
Subject Headings: Drug Delivery Systems, Nanoparticles, Manganese dioxide, Xanthan gum, Cancer cells
Format: Document (PDF)

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