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- Title
- Looking Into the Deep: Investigating Micro- and Nanoscale Biomineral Architecture of Marine Organisms Using Advanced Characterization Techniques.
- Creator
- Raja, Dawn May Somu, Merk, Vivian, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
Living organisms synthesize and assemble complex bioinorganic composites with enhanced structure and properties to fulfill needs such as structural support and enhanced mechanical function. With the advent of advanced materials characterization techniques, these biomineral systems can be explored with high resolution to glean information on their composition, ultrastructure, assembly, and biomechanics. In this work, the endoskeletal features of two marine organisms are explored. Acantharia...
Show moreLiving organisms synthesize and assemble complex bioinorganic composites with enhanced structure and properties to fulfill needs such as structural support and enhanced mechanical function. With the advent of advanced materials characterization techniques, these biomineral systems can be explored with high resolution to glean information on their composition, ultrastructure, assembly, and biomechanics. In this work, the endoskeletal features of two marine organisms are explored. Acantharia are geographically widespread marine planktonic single-celled organisms. Their star-shaped SrSO4 endoskeleton consists of spicules emanating from a central junction, arranged to satisfy crystallochemical and spatial requirements of their orthorhombic crystal lattice. In this work, synchrotron X-ray nanotomography and deep-learning guided image segmentation methods were used to characterize the endoskeleton of 5 types of Acantharia and to extrapolate their growth mechanism. The results highlight the diverse morphology of the spicules and spicular junctions that Acantharia achieve whilst maintaining overall spatial arrangement. Fine structural features, such as interspicular interstices thought to play a role in the robustness of the overall endoskeleton, were resolved.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014526
- Subject Headings
- Biomineralization, Materials science, Acantharia, Shark cartilage
- Format
- Document (PDF)
- Title
- DEVELOPMENT AND METHODOLOGY FOR AUV-BASED GEOMAGNETIC SURVEYS IN SUPPORT OF GEOPHYSICAL NAVIGATION.
- Creator
- Jepsen, Joshua, Dhanak, Manhar, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
This thesis investigates geomagnetic survey methodology in support of the development of a geophysical navigation system for an Autonomous Underwater Vehicle (AUV). Traditional AUV navigation methods are susceptible to cumulative errors and often rely on external infrastructure, limiting their effectiveness in complex underwater environments. This research leverages geomagnetic field anomalies as an additional navigational reference to these traditional systems, particularly in the absence of...
Show moreThis thesis investigates geomagnetic survey methodology in support of the development of a geophysical navigation system for an Autonomous Underwater Vehicle (AUV). Traditional AUV navigation methods are susceptible to cumulative errors and often rely on external infrastructure, limiting their effectiveness in complex underwater environments. This research leverages geomagnetic field anomalies as an additional navigational reference to these traditional systems, particularly in the absence of Global Positioning System (GPS) and acoustics navigation systems. Geomagnetic surveys were conducted over known shipwreck sites off the coast of Fort Lauderdale, Florida, to validate the system's ability to detect and map magnetic anomalies. Data from these surveys were processed to develop high-resolution geomagnetic contour maps, which were then analyzed for accuracy, reliability, and modeling in identifying geomagnetic features.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014527
- Subject Headings
- Geomagnetism, Geophysical surveys, Autonomous underwater vehicles
- Format
- Document (PDF)
- Title
- SYNERGETIC COMBINATION OF SEAWATER AND POLYMER-COATED NICKEL NANOPARTICLES FOR CO2 CAPTURE.
- Creator
- Abhishek, Kim, Myeongsub, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
Due to technological advancement, energy consumption and demand have been increasing significantly, primarily satisfied by fossil fuel utilization. The dependence on fossil fuels results in substantial greenhouse gas emissions, with CO₂ being the principal factor in global warming. Carbon capture technologies are employed to mitigate the escalated CO₂ emissions into the atmosphere. Among various carbon capture methods, amine scrubbing is widely utilized because of its high CO2 capture...
Show moreDue to technological advancement, energy consumption and demand have been increasing significantly, primarily satisfied by fossil fuel utilization. The dependence on fossil fuels results in substantial greenhouse gas emissions, with CO₂ being the principal factor in global warming. Carbon capture technologies are employed to mitigate the escalated CO₂ emissions into the atmosphere. Among various carbon capture methods, amine scrubbing is widely utilized because of its high CO2 capture efficiency and ease of adaptability to the existing power plants. This method, however, presents drawbacks, including increased toxicity, corrosiveness, and substantial freshwater use. To overcome these shortcomings and simultaneously develop an environmentally sustainable carbon capture solution, this study aims to evaluate the CO2 capture performance of seawater associated with polyvinylpyrrolidone (PVP) polymer-coated nickel nanoparticles (NiNPs) catalysts. Using high-speed bubble-based microfluidics, we investigated time-dependent size variations of CO2 bubbles in a flow-focusing microchannel, which is directly related to transient CO₂ dissolution into the surrounding solution. We hypothesize that the higher surface-to-volume ratio of polymer-coated NiNPs could provide a higher CO2 capture rate and solubility under the same environmental conditions. To test this hypothesis and to find the maximum performance of carbon capture, we synthesized polymer-coated NiNPs with different sizes of 5 nm, 10 nm, and 20 nm. The results showed that 5 nm polymer-coated NiNPs attained a CO₂ dissolution rate of 77% while it is 71% and 43% at 10 nm and 20 nm NPs, respectively. This indicates that our hypothesis is proven to be valid, suggesting that the smaller NPs catalyze CO2 capture effectively with using the same amount of material, which could be a game changer for future CO2 reduction technologies. This unique strategy promotes the future improvement of NiNPs as catalysts for CO2 capture from saltwater.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014557
- Subject Headings
- Nickel nanoparticles, Polyvinylpyrrolidone, Seawater, Carbon dioxide mitigation
- Format
- Document (PDF)
- Title
- NANOPARTICLE-INDUCED CATALYTIC CARBON CAPTURE: A MICROFLUIDICS APPROACH.
- Creator
- Donjuan, Joshua, Kim, Myeongsub, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
Due to technological advancement, energy consumption and demand have been increasing significantly, primarily satisfied by fossil fuel consumption. This reliance on fossil fuels results in substantial greenhouse gas emissions, with CO₂ being the most prominent contributor to global warming. To mitigate this issue and prevent CO₂ emissions, Carbon Capture, Utilization, and Storage (CCUS) technologies are employed. Among these, the amine scrubbing method is widely used due to its high CO2...
Show moreDue to technological advancement, energy consumption and demand have been increasing significantly, primarily satisfied by fossil fuel consumption. This reliance on fossil fuels results in substantial greenhouse gas emissions, with CO₂ being the most prominent contributor to global warming. To mitigate this issue and prevent CO₂ emissions, Carbon Capture, Utilization, and Storage (CCUS) technologies are employed. Among these, the amine scrubbing method is widely used due to its high CO2 capture efficiency and regenerative ability. However, this method has drawbacks, including high toxicity, corrosion, and substantial freshwater consumption. To develop an environmentally sustainable carbon capture solution, researchers are exploring alternatives such as the use of seawater and enhanced CO2 capture with catalysts. In this study, we analyze the catalytic performance of nickel nanoparticles (NiNPs) in seawater with carboxymethyl cellulose (CMC) polymers. Using flow-focusing geometry-based microfluidic channels, we investigated CO₂ dissolution at various concentrations of nanoparticles and CMC polymers. The objective is to optimize the concentration of nanoparticles and CMC polymers for effective CO₂ dissolution. We utilized NiNPs with diameters of 100 nm and 300 nm in CMC concentrations of 100 ml/L, 200 ml/L, and 300 ml/L. Additionally, NiNP concentrations ranging from 6 mg/L to 150 mg/L were tested for CO₂ dissolution in seawater. The results indicated that a concentration of 10 mg/L NiNPs in 100 mg/L CMC provided a CO₂ dissolution of 57%, the highest for this specific CMC concentration. At CMC concentrations of 200 ml/L and 300 ml/L, NiNP concentrations of 70 mg/L and 90 mg/L achieved CO₂ dissolution rates of 58.8% and 67.2%, respectively.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014483
- Subject Headings
- Carbon sequestration, Global warming, Polymer chemistry, Nanoparticles
- Format
- Document (PDF)
- Title
- SPONTANEOUS HYDROGEN GENERATION WITH SILICON NANOPARTICLES AND WATER.
- Creator
- Axelrod, Kevin Eric, Kim, Myeongsub, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
Over the past decade, hydrogen gas generation has been a critical component toward clean energy due to its high specific energy content. Generating hydrogen gas from water is crucial for future applications, including space transportation. Recent studies show promising results using silicon nanoparticles (SiNPs) for spontaneous hydrogen generation, but most methods require external energy like high temperature or pressure. In this work, we investigated hydrogen production from SiNPs without...
Show moreOver the past decade, hydrogen gas generation has been a critical component toward clean energy due to its high specific energy content. Generating hydrogen gas from water is crucial for future applications, including space transportation. Recent studies show promising results using silicon nanoparticles (SiNPs) for spontaneous hydrogen generation, but most methods require external energy like high temperature or pressure. In this work, we investigated hydrogen production from SiNPs without external energy by leveraging high pH water using sodium hydroxide and optimizing the process with a microfluidic approach. When comparing the physical dispersion methods using the 0.1 mg/mL case, ultrasonic bath produced more hydrogen than magnetic stirrer. In this thesis, 0.01% dextran with pure SiNPs at concentrations of 0.1 mg/mL, 0.2 mg/mL, and 0.3 mg/mL was analyzed. The highest concentration with dextran generated at least 40% less hydrogen than silicon alone, thus dextran did not increase hydrogen gas.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014480
- Subject Headings
- Hydrogen, Hydrogen as fuel, Silicon, Nanoparticles
- Format
- Document (PDF)
- Title
- MULTIPHYSICS SIMULATION OF DIELECTROPHORESIS ENRICHMENT FOR DETECTION OF LOW PARASITEMIA PLASMODIUM FALCIPARUM IN HUMAN BLOOD.
- Creator
- Oladokun, Oladiran, Du, E., Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
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Malaria is an ancient lethargic disease that remains a global burden. It has been difficult to end the scourge of P. falciparum malaria because of the parasites’ drug resistance so early diagnosis of malaria is crucial. Microscopy remains the gold standard but has limited reliability in detecting malaria parasites. This study proffered a method towards detection of low parasitemia P. falciparum infected RBCs (Pf-RBCs) based on dielectrophoresis (DEP). A microfluidic device was designed for...
Show moreMalaria is an ancient lethargic disease that remains a global burden. It has been difficult to end the scourge of P. falciparum malaria because of the parasites’ drug resistance so early diagnosis of malaria is crucial. Microscopy remains the gold standard but has limited reliability in detecting malaria parasites. This study proffered a method towards detection of low parasitemia P. falciparum infected RBCs (Pf-RBCs) based on dielectrophoresis (DEP). A microfluidic device was designed for label-free cell sorting of Pf-RBCs from other whole blood in a continuous manner, based on the intrinsic electrical signatures of the cells. The design was validated by a finite element simulation using COMSOL Multiphysics. Simulations show the feasibility of the separation in a 9-mm long microfluidic channel under laminar flow conditions, using a low voltage supply of +/-10 V at 50 kHz.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014415
- Subject Headings
- Plasmodium falciparum, Microfluidic devices, Dielectrophoresis, Biomedical engineering, Point-of-care testing
- Format
- Document (PDF)
- Title
- MODELING, IMPLEMENTATION AND CONTROL OF A CVT BASED PTO FOR A SMALL SCALE MHK-TURBINE IN LOW FLOW SPEED OPERATION.
- Creator
- Pimentel, Hugo, Dhanak, Manhar, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
Modeling, implementation, field testing and control of a power takeoff (PTO) device equipped with a ball-type continuously variable transmission (B-CVT) for a small marine hydrokinetic (MHK) turbine deployed from a floating unmanned autonomous mobile catamaran platform is described. The turbine is a partially submerged multi-blade undershot waterwheel (USWW). A validated numerical torque model for the MHK turbine has been derived and a speed controller has been developed, implemented and...
Show moreModeling, implementation, field testing and control of a power takeoff (PTO) device equipped with a ball-type continuously variable transmission (B-CVT) for a small marine hydrokinetic (MHK) turbine deployed from a floating unmanned autonomous mobile catamaran platform is described. The turbine is a partially submerged multi-blade undershot waterwheel (USWW). A validated numerical torque model for the MHK turbine has been derived and a speed controller has been developed, implemented and tested in the field. The dependance of the power generated as a function of number and submergence level of turbine blades has been investigated and the number of blades that maximizes power production is determined. Bench and field testing in support of characterizing the power conversion capabilities of MHK turbine and PTO are described. Detailed results of the final torque and power coefficient models, the controls architecture, and the MHK turbine performance with varying numbers of blades are provided.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014417
- Subject Headings
- Marine turbines, Renewable energy, Marine turbines--Transmission devices, Continuously variable transmission
- Format
- Document (PDF)
- Title
- SMALL UNMANNED MARINE HYDROKINETIC PLATFORMS FOR POWER GENERATION IN COASTAL AND TIDAL WATERS.
- Creator
- McKinney, Adriana, Dhanak, Manhar, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
The feasibility and optimization of small unmanned mobile marine hydrokinetic (MHK) energy platforms for harvesting marine current energy in coastal and tidal waters are examined. A case study of a platform based on the use of a free-surface waterwheel (FSWW) mounted on an autonomous unmanned surface vehicle (USV) was conducted. Such platforms can serve as recharging stations for aerial drones (UAVs), enabling extension of the UAVs’ autonomous operating time. An unmanned MHK platform...
Show moreThe feasibility and optimization of small unmanned mobile marine hydrokinetic (MHK) energy platforms for harvesting marine current energy in coastal and tidal waters are examined. A case study of a platform based on the use of a free-surface waterwheel (FSWW) mounted on an autonomous unmanned surface vehicle (USV) was conducted. Such platforms can serve as recharging stations for aerial drones (UAVs), enabling extension of the UAVs’ autonomous operating time. An unmanned MHK platform potentially meets this need with sustainable power harvested from water currents. For the case study, six different waterwheel configurations were field-tested in the Intracoastal Waterway of South Florida in support of determining the configuration that produced the most power. Required technologies for unmanned operations of the MHK platform were developed and tested. The data from the field-testing were analyzed to develop an empirical relation between the wheel’s theoretical hydrokinetic power produced and the mechanical power harnessed by the MHK platform with various waterwheel configurations during field-testing. The field data was also used to determine the electrical power generated by the FSWW configurations during field-testing. The study has led to the development of standardized testing procedures. The empirical relation is used to examine predicted power production through scaling up different physical aspects of the waterwheel.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014412
- Subject Headings
- Ocean engineering, Renewable energy, Marine turbines
- Format
- Document (PDF)
- Title
- EXPLORING UNDULATORY SWIMMING BEHAVIORS WITH DEEP REINFORCEMENT LEARNING.
- Creator
- Alvaro, Alejandro, Verma, Siddhartha, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
The capability to navigate in the proximity of solid surfaces while avoiding collision and maintaining high efficiency is essential for the effective design and operation of underwater vehicles. The underlying capability involves a variety of challenges, and a potential approach to overcome such obstacles is to rely on biomimetic or bio-inspired design. Through evolution, organisms have developed methods of locomotion optimized for their specific environment. One of the common forms of...
Show moreThe capability to navigate in the proximity of solid surfaces while avoiding collision and maintaining high efficiency is essential for the effective design and operation of underwater vehicles. The underlying capability involves a variety of challenges, and a potential approach to overcome such obstacles is to rely on biomimetic or bio-inspired design. Through evolution, organisms have developed methods of locomotion optimized for their specific environment. One of the common forms of locomotion found in underwater organisms is undulatory swimming. These undulatory swimmers display different swimming behaviors based on the flow conditions in their environment. These behaviors take advantage of changes in the flow field caused by the presence of obstructions and obstacles upstream or adjacent to the swimmer. For example, a free swimmer in near-proximity to a flat plane can experience changes in lift and drag during locomotion. The reduced drag can benefit the swimmer, however, changes in lift may lead to a collision with obstacles. Despite the abundance of qualitative data from observing these undulatory swimmers, there is a lack of quantitative data, creating a disconnect in understanding how these organisms have evolved to exploit the presence of walls and obstacles. By employing a combination of traditional computational fluid dynamics and novel neural network-based techniques it is possible to emulate the evolution of learned behavior in biological organisms. The current work uses deep reinforcement learning coupled with two-dimensional numerical simulations of self-propelled swimmers to better understand behavior observed in nature.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014402
- Subject Headings
- Reinforcement learning, Computational fluid dynamics, Autonomous underwater vehicles
- Format
- Document (PDF)
- Title
- FLOW-MEDIATED NAVIGATION AND COORDINATION OF ARTIFICIAL SWIMMERS USING DEEP REINFORCEMENT LEARNING.
- Creator
- Nair, Aishwarya, Verma, Siddhartha, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
Aquatic organisms are able to achieve swimming efficiencies that are much higher than any underwater vehicle that has been designed by humans. This is mainly due to the adaptive swimming patterns that they display in response to changes in their environment and their behaviors, i.e., hunting, fleeing, or foraging. In this work, we explore these adaptations from a hydrodynamics standpoint, using numerical simulations to emulate self-propelled artificial swimmers in various flow fields. Apart...
Show moreAquatic organisms are able to achieve swimming efficiencies that are much higher than any underwater vehicle that has been designed by humans. This is mainly due to the adaptive swimming patterns that they display in response to changes in their environment and their behaviors, i.e., hunting, fleeing, or foraging. In this work, we explore these adaptations from a hydrodynamics standpoint, using numerical simulations to emulate self-propelled artificial swimmers in various flow fields. Apart from still or uniform flow, the most likely flow field encountered by swimmers are those formed by the wakes of solid objects, such as roots of aquatic vegetation, or underwater structures. Therefore, a simplified bio-inspired design of porous structures consisting of nine cylinders was considered to identify arrangements that could produce wakes of varying velocities and enstrophy, which in turn might provide beneficial environments for underwater swimmers. These structures were analyzed using a combination of numerical simulations and experiments, and the underlying flow physics was examined using a variety of data-analysis techniques. Subsequently, in order to recreate the adaptations of natural swimmers in different flow regimes, artificial swimmers were positioned in each of these different types of flow fields and then trained to optimize their movements to maximize swimming efficiency using deep reinforcement learning. These artificial swimmers utilize a sensory input system that allows them to detect the velocity field and pressure on the surface of their body, which is similar to the lateral line sensing system in biological fish. The results demonstrate that the information gleaned from the simplified lateral line system was sufficient for the swimmer to replicate naturally found behaviors such as K´arm´an gaiting. The phenomenon of schooling in underwater organisms is similarly thought to provide opportunities for swimmers to increase their energy efficiency, along with the other associated benefits. Thus, multiple swimmers were trained using multi-agent reinforcement learning to discover optimal swimming patterns at the group level as well as the individual level.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014413
- Subject Headings
- Reinforcement learning, Hydrodynamics, Computational fluid dynamics, .
- Format
- Document (PDF)
- Title
- THE DETECTABILITY OF GOLIATH GROUPER SOUNDS IN NEARSHORE WATERS USING A NORMAL MODES PROPAGATION MODEL.
- Creator
- Marcheggiani, Joseph P., Cherubin, Laurent, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
This research presents findings from an in-situ experiment utilizing a hydrophone line array to capture the sound production of the Goliath grouper. Analysis revealed that Goliath grouper calls exhibit multiple frequency components, including one high-amplitude component and 2 to 3 low-amplitude components. The primary high-amplitude component is concentrated in the 30 to 70 Hz band, peaking around 50 Hz, while low-amplitude components span 20 to 30 Hz, 70 to 115 Hz, and 130 to 200 Hz....
Show moreThis research presents findings from an in-situ experiment utilizing a hydrophone line array to capture the sound production of the Goliath grouper. Analysis revealed that Goliath grouper calls exhibit multiple frequency components, including one high-amplitude component and 2 to 3 low-amplitude components. The primary high-amplitude component is concentrated in the 30 to 70 Hz band, peaking around 50 Hz, while low-amplitude components span 20 to 30 Hz, 70 to 115 Hz, and 130 to 200 Hz. Comparison between in-situ data and results from a normal modes transmission loss model identified regions where echo level increased with propagation distance. This suggests that the loudness of the call may not necessarily indicate proximity, indicating the Goliath grouper might rely on other cues for localization, such as changes in the frequency profile of its call. Two methods for estimating call distance are presented. The first method vi utilized a transmission loss model and measured transmission loss across a hydrophone line array. This method could also determine the source level of the calls, yielding source level estimates ranging from 124.01 to 144.83 dB re 1 μPa. The second method employed match field filtering, validating the accuracy of the transmission loss model. Both methods produced similar call distance estimations, ranging from 11.5 to 17.1 meters, placing the grouper inside or near its typical habitat.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014377
- Subject Headings
- Epinephelus itajara, Groupers, Fish sounds, Acoustics, Sound--Transmission
- Format
- Document (PDF)
- Title
- INFLUENCE OF DEFORMATION CONSTRAINTS OF HONEYCOMB CORE CELLS ON THE BENDING STIFFNESS OF SINGLE-FACE SANDWICH.
- Creator
- Ayanoglu, Mustafa Oguzhan, Carlsson, Leif A., Du, E, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
This research focuses on deformation constraints of honeycomb core cells in a sandwich imposed by bonds to the face sheets. Specifically, the influence of one-sided core constraints on the bending stiffness of a single-face honeycomb core sandwich is examined. To characterize the unconstrained in-plane compressive response of honeycomb core, a range of honeycomb cores was experimentally examined. Cores with a thin cell wall displayed extensive bending deformation of inclined cell walls while...
Show moreThis research focuses on deformation constraints of honeycomb core cells in a sandwich imposed by bonds to the face sheets. Specifically, the influence of one-sided core constraints on the bending stiffness of a single-face honeycomb core sandwich is examined. To characterize the unconstrained in-plane compressive response of honeycomb core, a range of honeycomb cores was experimentally examined. Cores with a thin cell wall displayed extensive bending deformation of inclined cell walls while cores with thicker walls failed by a shear-type instability of the cells indicated by tilting of vertical cell wall segments. The modulus and compressive strength of the core were compared to the predictions from unit cell models. The results show that geometrical imperfections such as deviation from the intended cell wall angle cause in-plane anisotropy and have strong influence on modulus and strength of the core. Modulus and strength were in reasonable agreement with predictions from unit cell models for cell wall modulus and strength between 5-12 GPa and 72-171 MPa for the set of cores examined.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014438
- Subject Headings
- Honeycomb structures, Materials--Compression testing, Sandwich construction
- Format
- Document (PDF)
- Title
- ATTITUDE MEASURING SENSOR FOR A TOWED BODY.
- Creator
- Flitton, Garrett, Dhanak, Manhar, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
The Design and Development of a remote attitude-measuring sensor package (RASP) for use onboard an underwater tow fish to analyze its dynamic movement while towing is described. The RASP will be used to determine the orientation, acceleration, and gyroscopic attitude of the tow fish. The collection of this data is important for understanding the trim of the tow fish under different towing conditions behind a manned surface vessel or unmanned underwater vehicle. The trim data acquired will...
Show moreThe Design and Development of a remote attitude-measuring sensor package (RASP) for use onboard an underwater tow fish to analyze its dynamic movement while towing is described. The RASP will be used to determine the orientation, acceleration, and gyroscopic attitude of the tow fish. The collection of this data is important for understanding the trim of the tow fish under different towing conditions behind a manned surface vessel or unmanned underwater vehicle. The trim data acquired will inform the extent to which post-processing of collected three-axis electromagnetic field data would be required. The RASP has been analyzed in the laboratory with a mechanical testing rig that was designed and built to validate the accuracy and performance of the entire sensor package system. The developed package will aid in the assessment of the performance of the tow fish in field operations with the sensor package implemented on the tow fish.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014423
- Subject Headings
- Sensors, Marine towing, Electromagnetic fields
- Format
- Document (PDF)
- Title
- BACKGROUND STRUCTURE FUNCTIONS, A BASIS TO REDUCE ACOUSTIC POWER REQUIREMENTS AND IMPROVE IMAGES.
- Creator
- Kobold, Michael C., Beaujean, Pierre-Philippe J., Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
Background Structure Functions (BSFs) are wavefront distortion metrics, functions of Sound Speed Profiles (SSPs) that are functions of depth. Use of these BSFs is a synthesis form of Matched Field Processing (MFP) that detects signals that are otherwise lost to receivers. Underwater Acoustics (UWA) can use these models to forecast communication and imaging performance and to reduce power radiated into the sea. This reduction of Transmission Loss (TL) occurs because the commercial wavefront...
Show moreBackground Structure Functions (BSFs) are wavefront distortion metrics, functions of Sound Speed Profiles (SSPs) that are functions of depth. Use of these BSFs is a synthesis form of Matched Field Processing (MFP) that detects signals that are otherwise lost to receivers. Underwater Acoustics (UWA) can use these models to forecast communication and imaging performance and to reduce power radiated into the sea. This reduction of Transmission Loss (TL) occurs because the commercial wavefront control has an input format that accepts BSFs. The BSF plots represent the purely statistical distortion for communications and remote sensing. Another source of TL reduction comes from the enclosed BSF-based phase and phase variance forecasting that protects equalizers from losing phase-lock. Protecting the equalizers protects the Signal To Noise (SNR) ratios. This dissertation derives the UWA version of these metrics and applies them to the following locations of our SSPs: The BSFs use measured, corrected, and verified SSP groups for 132 different locations in the Atlantic Ocean and the Gulf of Mexico from a Navy Ocean Atlas, as well as 64 SSPs in two areas in the littorals, Port Everglades, and Saint Andrew Bay, plus tidal variations. Since BSFs digitize the propagation into one or more segments, our purely statistical phase screen model uses only 3 or 4 degrees of freedom (DOFs) per segment compared to many dozen DOFs for conventional structure functions. The BSFs forecast communications and imaging performance, including range, in locations where acoustic measurements are not available, but SSPs are. A separate algorithm forecasts Gouy phase anomalies from background SSPs, which otherwise requires a priori knowledge of anomaly location and use of Catastrophe theory due to ray theory failure at focuses. Avoiding these anomalies and loss of Phase-Locked Loops (PLLs) also helps maintain SNR and lowers transmission power requirements. Combining with phase parameters and performance forecasts improves UWA propagation efficiency using the background (SSPs). In a spatial version of delay equalization, BSF analysis also produces the enclosed Shear Distortion Ratios (SDRs) for the same locations mentioned above, to allow optimum selection of image enhancement algorithms that mitigate image shear distortion.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014395
- Subject Headings
- Underwater acoustics, Sound--Speed, Ocean engineering
- Format
- Document (PDF)
- Title
- Acoustic Tonal and Vector Properties of Red Hind Grouper Vocalizationd.
- Creator
- Matthews, Cameron Anthony, Beaujean, Pierre-Philippe, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Vertebrates are the most prodigious vocalizing animals in existence, and the most diverse methods of acoustic communication among vertebrates can be found in the ocean. Relatively many teleost fish are gifted with the ability to communicate acoustically, and the family of serranidae often performs this as a function of the swim bladder. Epinephelus Guttatus (E. guttatus), or more commonly the red hind grouper, is equipped with a drum shaped swim bladder acting as a monopole under typical...
Show moreVertebrates are the most prodigious vocalizing animals in existence, and the most diverse methods of acoustic communication among vertebrates can be found in the ocean. Relatively many teleost fish are gifted with the ability to communicate acoustically, and the family of serranidae often performs this as a function of the swim bladder. Epinephelus Guttatus (E. guttatus), or more commonly the red hind grouper, is equipped with a drum shaped swim bladder acting as a monopole under typical ocean conditions. This configuration allows for what is understood to be omnidirectional projection of tones approximately centered between 40 and 440 Hz and spanning anywhere from 40 to 200 Hz of bandwidth and modulation effects based on observed data provided by researchers. Prior studies on many other fish show correlation in acoustic communication profile with length, size and sexual identity. In the red hind, sexual dimorphism leads to an inherent female identity in all juvenile fish which converts to male according to environmental factors, recommending at least consistent organs across both sexes be assumed even if not in use. Much research has been performed on male fish vocalization in terms of spectral content. Communication in fish is a complex multi-modal process, with acoustic communication being important for many of the species, particularly those in the littoral regions of the worlds’ oceans. If identifying characteristics of the red hind vocalization can be isolated based on detection, classification, tracking and localizing methodologies, then these identifying characteristics may indeed lead to passive feature identification that allows for estimation of individual fish mass. Hypotheses based on vector, cyclostationary and classical tonal mechanics are presented for consideration. A battery of test data collection events, applying pre-recorded fish vocalizations to a geolocated undersea sound source were conducted. The results are supplied with the intent of validating hypothesis in a non-expert system manner that shows how a series of biological metrics may be assessed for detection, classification, localization and mass estimation for an individual vocalizing red hind grouper
Show less - Date Issued
- 2017
- PURL
- http://purl.flvc.org/fau/fd/FA00004826, http://purl.flvc.org/fau/fd/FA00004826
- Subject Headings
- Wave-motion, Theory of., Sound production by animals., Fishes--Vocalization., Bioacoustics., Animal communication., Underwater acoustics., Acoustic surface waves.
- Format
- Document (PDF)
- Title
- Propulsive performance of an under-actuated robotic ribbon fin.
- Creator
- Liu, Hanlin, Curet, Oscar M
- Date Issued
- 2017-06-02
- PURL
- http://purl.flvc.org/fau/flvc_fau_islandoraimporter_10.1088_1748-3190_aa7184_1642527109
- Format
- Document (PDF)
- Title
- Motion-Compensated Acoustic Positioning in Very Shallow Waters Using Spread-Spectrum Signaling and a Tetrahedral Ultrashort Baseline Array.
- Creator
- Beaujean, Pierre-Philippe J., Bon, Antoine, An, Edgar
- Date Issued
- 2010-09-01
- PURL
- http://purl.flvc.org/fau/flvc_fau_islandoraimporter_10.4031_MTSJ.44.5.4_1629744733
- Format
- Citation
- Title
- The Comprehensive Evaluation of Performance and Environmental Influence on MPSK Modulated High-Speed Acoustic Communications in Shallow Water.
- Creator
- Proteau, Joshua C., Beaujean, Pierre-Philippe, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A daily study spanning a month of the shallow water acoustic channel was conducted to estimate the environmental influence on performance of an underwater acoustic communications system. An automated acoustic modem transmitted phase-coherent modulated sequences of identical data with 186 dB re IpPa source level, at coded rates from 4000 to 16000 bits/s with 4 or 8 kHz symbol bandwidth, three times daily for a month. A 64 channel Mills-Cross receiver array was used with horizontal and vertical...
Show moreA daily study spanning a month of the shallow water acoustic channel was conducted to estimate the environmental influence on performance of an underwater acoustic communications system. An automated acoustic modem transmitted phase-coherent modulated sequences of identical data with 186 dB re IpPa source level, at coded rates from 4000 to 16000 bits/s with 4 or 8 kHz symbol bandwidth, three times daily for a month. A 64 channel Mills-Cross receiver array was used with horizontal and vertical beams each containing 32 and 33 elements respectively, spaced 0.03 meters apart, with a sampling frequency of 72 kHz. Source and receiver were deployed at depths of 20 meters respectively, with a 720 meter separation range. Environmental measurements of wind velocity and direction, surface wave activity, current and sound velocity profiles, and tidal measurements were performed. Results demonstrate reliable achievement of high data-rate shallow water acoustic communications using phase-coherent modulation techniques.
Show less - Date Issued
- 2006
- PURL
- http://purl.flvc.org/fau/fd/FA00012541
- Subject Headings
- Underwater acoustics--Measurement, Artificial satellites in telecommunication, Underwater acoustic telemetry, Signal processing--Digital techniques
- Format
- Document (PDF)
- Title
- Numerical Simulation of an Ocean Current Turbine Operating in a Wake Field.
- Creator
- Pyakurel, Parakram, VanZwieten, James H., Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
An Ocean Current Turbine (OCT) numerical simulation for creating, testing and tuning flight and power takeoff controllers, as well as for farm layout optimization is presented. This simulation utilizes a novel approach for analytically describing oceanic turbulence. This approach has been integrated into a previously developed turbine simulation that uses unsteady Blade Element Momentum theory. Using this, the dynamical response and power production of a single OCT operating in ambient...
Show moreAn Ocean Current Turbine (OCT) numerical simulation for creating, testing and tuning flight and power takeoff controllers, as well as for farm layout optimization is presented. This simulation utilizes a novel approach for analytically describing oceanic turbulence. This approach has been integrated into a previously developed turbine simulation that uses unsteady Blade Element Momentum theory. Using this, the dynamical response and power production of a single OCT operating in ambient turbulence is quantified. An approach for integrating wake effects into this single device numerical simulation is presented for predicting OCT performance within a farm. To accomplish this, far wake characteristics behind a turbine are numerically described using analytic expressions derived from wind turbine wake models. These expressions are tuned to match OCT wake characteristics calculated from CFD analyses and experimental data. Turbine wake is characterized in terms of increased turbulence intensities and decreased mean wake velocities. These parameters are calculated based on the performance of the upstream OCT and integrated into the environmental models used by downstream OCT. Simulation results are presented that quantify the effects of wakes on downstream turbine performance over a wide range of relative downstream and cross stream locations for both moored and bottom mounted turbine systems. This is done to enable the development and testing of flight and power takeoff controllers designed for maximizing energy production and reduce turbine loadings.
Show less - Date Issued
- 2016
- PURL
- http://purl.flvc.org/fau/fd/FA00004737, http://purl.flvc.org/fau/fd/FA00004737
- Subject Headings
- Turbulence--Mathematical models., Marine turbines--Mathematical models., Wind turbines--Aerodynamics--Mathematical models., Structural dynamics., Computational fluid dynamics., Fluid dynamic measurements., Atmospheric circulation.
- Format
- Document (PDF)
- Title
- Optimization of an Ocean Current Turbine Design and Prediction of Wake Propagation in an Array.
- Creator
- Kawssarani, Ali, VanZwieten, James H., Seiffert, Betsy, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This research focused on maximizing the power generated by an array of ocean current turbines. To achieve this objective, the produced shaft power of an ocean current turbine (OCT) has been quantified using CFD without adding a duct, as well as over a range of duct geometries. For an upstream duct, having a diameter 1.6 times the rotor diameter, the power increased by 8.35% for a duct that extends 1 diameter upstream. This research also focused on turbine array optimization, providing a...
Show moreThis research focused on maximizing the power generated by an array of ocean current turbines. To achieve this objective, the produced shaft power of an ocean current turbine (OCT) has been quantified using CFD without adding a duct, as well as over a range of duct geometries. For an upstream duct, having a diameter 1.6 times the rotor diameter, the power increased by 8.35% for a duct that extends 1 diameter upstream. This research also focused on turbine array optimization, providing a mathematical basis for calculating the water velocity within an array of OCTs. After developing this wake model, it was validated using experimental data. As the downstream distance behind the turbine increases, the analytic results become closer to the experimental results, with a difference of 3% for TI = 3% and difference of 4% for TI = 15%, both at a downstream distance of 4 rotor diameters.
Show less - Date Issued
- 2018
- PURL
- http://purl.flvc.org/fau/fd/FA00013077
- Subject Headings
- Turbines--Design and construction., Marine turbines., Ocean current energy, Ocean wave power
- Format
- Document (PDF)
