Current Search: Magnetic fields (x)
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- Title
- EFFECTIVENESS OF A MAGNETIC SHARK DETERRENT.
- Creator
- Jones, Laura, Kajiura, Stephen, Florida Atlantic University, Department of Marine Science and Oceanography, Charles E. Schmidt College of Science
- Abstract/Description
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This study examined the effectiveness of a magnetic shark deterrent, the SharkBanz® Zeppelin, and quantified the magnetic field it produces. A shark entering the magnetic field induces an electric field that is detectable by electroreceptors. This novel stimulus may deter sharks away from hooked fish. The magnitude declined rapidly with distance and reached the ambient geomagnetic field at 36-39 cm away. Zeppelin devices and non-magnetic controls were deployed with baited remote underwater...
Show moreThis study examined the effectiveness of a magnetic shark deterrent, the SharkBanz® Zeppelin, and quantified the magnetic field it produces. A shark entering the magnetic field induces an electric field that is detectable by electroreceptors. This novel stimulus may deter sharks away from hooked fish. The magnitude declined rapidly with distance and reached the ambient geomagnetic field at 36-39 cm away. Zeppelin devices and non-magnetic controls were deployed with baited remote underwater video systems, and the responses of sharks were recorded. There was a significant difference between the number of sharks deterred between the Zeppelin and control. The Zeppelin deterred sharks on 22% of their approaches in the effective range, whereas the control deterred them on 2.6% of their approaches. Although the device may be effective at deterring sharks and act as a mitigation strategy for shark depredation, tests with live fish that provide more sensory stimuli are needed.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014556
- Subject Headings
- Sharks, Elasmobranchs, Magnetic fields, Electromagnetics
- Format
- Document (PDF)
- Title
- Orientation of hatchling loggerhead sea turtles in response to the inclination of the magnetic field.
- Creator
- Light, Phillip Richard, Florida Atlantic University, Salmon, Michael, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
Recent studies have shown that hatchling loggerhead sea turtles possess the ability to orient to the earth's magnetic field. These experiments did not identify the specific component of the field used by turtles to determine direction. One of the field's most important characteristics, inclination, has been implicated as the specific property used by birds to orient. This study investigated the possibility that sea turtles use the inclination of the earth's field in a similar manner. Results...
Show moreRecent studies have shown that hatchling loggerhead sea turtles possess the ability to orient to the earth's magnetic field. These experiments did not identify the specific component of the field used by turtles to determine direction. One of the field's most important characteristics, inclination, has been implicated as the specific property used by birds to orient. This study investigated the possibility that sea turtles use the inclination of the earth's field in a similar manner. Results show that turtles determine direction with the use of an inclination compass similar to the one used by birds to orient. This study has important implications regarding the mechanisms used by animals to orient and navigate.
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/14787
- Subject Headings
- Loggerhead turtle, Animal orientation, Magnetic fields, Sea turtles--Migration
- Format
- Document (PDF)
- Title
- Computer Simulation of Charged Particle Trajectories.
- Creator
- Hogan, William A., Lamborn, Bjorn, Florida Atlantic University
- Abstract/Description
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A computer analysis is made of the trajectories of charged particles injected tangentially into the mid-plane of a static mirror field. Conditions necessary for the non-adiabatic transfer of particle energy from the plane perpendicular to the field to the direction parallel to the field are discussed. Two distinct mechanisms are observed: (1) When the requirements for parametric resonance are satisfied, energy is absorbed into longitudinal motion; and (2) When the particle exhibits the...
Show moreA computer analysis is made of the trajectories of charged particles injected tangentially into the mid-plane of a static mirror field. Conditions necessary for the non-adiabatic transfer of particle energy from the plane perpendicular to the field to the direction parallel to the field are discussed. Two distinct mechanisms are observed: (1) When the requirements for parametric resonance are satisfied, energy is absorbed into longitudinal motion; and (2) When the particle exhibits the characteristic looping behavior, energy may be transferred between the longitudinal and transverse degrees of freedom. Various numerical methods are employed to integrate the equations of motion. The fourthorder Runge-Kutta Method is found to be the most accurate.
Show less - Date Issued
- 1970
- PURL
- http://purl.flvc.org/fau/fd/FA00000753
- Subject Headings
- Magnetic fields--Computer programs, Plasma confinement, Equations of motion
- Format
- Document (PDF)
- Title
- Placement and Denoising of Total Magnetic Field Sensors Onboard an AUV in Support of Geophysical Navigation.
- Creator
- Cracchiolo, Timothy, Beaujean, Pierre-Philippe, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
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The objective of this thesis is to study the proper placement and denoising of Total Field Magnetometers (TFM) installed on an Autonomous Underwater Vehicle (AUV), in support of a long-term goal to perform geophysical navigation based on total field magnetic sensing. This new form of navigation works by using the magnetic field of the Earth as a source of reference to find the desired heading. The primary tools used in this experiment are a REMUS 100 AUV, a QuSpin scalar magnetometer, and a...
Show moreThe objective of this thesis is to study the proper placement and denoising of Total Field Magnetometers (TFM) installed on an Autonomous Underwater Vehicle (AUV), in support of a long-term goal to perform geophysical navigation based on total field magnetic sensing. This new form of navigation works by using the magnetic field of the Earth as a source of reference to find the desired heading. The primary tools used in this experiment are a REMUS 100 AUV, a QuSpin scalar magnetometer, and a TwinLeaf vector magnetometer. The Earth’s magnetic field was measured over periods of several hours to determine the range of values it provides under natural conditions. Digital filters were created to digitally reduce fluctuations caused by sources of external interference and sources of internal interference. To mitigate the issue of platform based interference, two methods were examined. These methods involved the use of the Tolles-Lawson model and Wavelet Multiresolution Analysis. The Tolles-Lawson model is used to determine the compensation coefficients from a calibration mission to mitigate the effects from the permanently detected magnetic field, the induced magnetic field, eddy currents. and the geomagnetic field. Wavelet multiresolution analysis follows the same basic steps as Fourier transformations and is used to analyze time series with power sources in motion over a frequency spectrum. Several acquisitions were run with the QuSpin in various locations around and along REMUS, and it was concluded that placing the sensor at the very front of the vessel which is approximately 1.8 [m] from the DC motor, with assistance from wavelet analysis was acceptable for the project.
Show less - Date Issued
- 2022
- PURL
- http://purl.flvc.org/fau/fd/FA00013972
- Subject Headings
- Autonomous underwater vehicles, Magnetometers, Magnetic fields, Remote sensing
- Format
- Document (PDF)
- Title
- Cognitive and magnetosensory ecology of the yellow stingray, Urobatis jamaicensis.
- Creator
- Newton, Kyle C., Kajiura, Stephen M., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
Elasmobranchs (sharks, skates, and rays) migrate across a wide range of spatiotemporal scales, display philopatry, seasonal residency, and maintain home ranges. Many animals use the Earth’s magnetic field to orient and navigate between habitats. The geomagnetic field provides a variety of sensory cues to magnetically sensitive species, which could potentially use the polarity, or intensity and inclination angle of the field, to derive a sense of direction, or location, during migration....
Show moreElasmobranchs (sharks, skates, and rays) migrate across a wide range of spatiotemporal scales, display philopatry, seasonal residency, and maintain home ranges. Many animals use the Earth’s magnetic field to orient and navigate between habitats. The geomagnetic field provides a variety of sensory cues to magnetically sensitive species, which could potentially use the polarity, or intensity and inclination angle of the field, to derive a sense of direction, or location, during migration. Magnetoreception has never been unequivocally demonstrated in any elasmobranch species and the cognitive abilities of these fishes are poorly studied. This project used behavioral conditioning assays that paired magnetic and reinforcement stimuli in order to elicit behavioral responses. The specific goals were to determine if the yellow stingray, Urobatis jamaicensis, could detect magnetic fields, to quantify the nature of the magnetic stimuli it could detect, and to quantify the learning and memory capabilities of this species. The results supported the original hypotheses and demonstrated that the yellow stingray could: discriminate between magnetic and non-magnetic objects; detect and discriminate between changes in geomagnetic field strength and inclination angle; and use geomagnetic field polarity to solve a navigational task. The yellow stingray learned behavioral tasks faster and retained the memories of learned associations longer than any batoid (skate or ray) to date. The data also suggest that this species can classify magnetic field stimuli into categories and learn similar behavioral tasks with increased efficiency, which indicate behavioral flexibility. These data support the idea that cartilaginous fishes use the geomagnetic field as an environmental cue to derive a sense of location and direction during migrations. Future studies should investigate the mechanism, physiological threshold, and sensitivity range of the elasmobranch magnetic sense in order to understand the effects of anthropogenic activities and environmental change on the migratory ability of these fishes.
Show less - Date Issued
- 2017
- PURL
- http://purl.flvc.org/fau/fd/FA00004883, http://purl.flvc.org/fau/fd/FA00004883
- Subject Headings
- Animal behavior., Animal migration., Magnetic fields--Physiological effect., Senses and sensation., Adaptation (Biology)
- Format
- Document (PDF)
- Title
- Magnetic orientation of loggerhead sea turtle hatchlings: migratory strategies in the Gulf of Mexico.
- Creator
- Merrill, Maria W., Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
Loggerhead sea turtles nest on either the Atlantic or Gulf coast of Florida. The hatchlings from these nests migrate offshore in opposite directions. The purpose of my study was to determine if Gulf coast hatchlings use magnetic maps, as Atlantic coast hatchlings do, both to locate areas favorable for survival in the Gulf of Mexico and to orient appropriately within surface currents that could transport them into the Atlantic Ocean. To find out, I presented Gulf coast hatchlings with magnetic...
Show moreLoggerhead sea turtles nest on either the Atlantic or Gulf coast of Florida. The hatchlings from these nests migrate offshore in opposite directions. The purpose of my study was to determine if Gulf coast hatchlings use magnetic maps, as Atlantic coast hatchlings do, both to locate areas favorable for survival in the Gulf of Mexico and to orient appropriately within surface currents that could transport them into the Atlantic Ocean. To find out, I presented Gulf coast hatchlings with magnetic fields corresponding to different locations inside the Gulf, and within currents leading into (Florida Straits) and within (Gulf Stream) the western portion of the Atlantic Ocean. I conclude that Gulf coast hatchlings (i) use a high resolution magnetic map for navigation within the Gulf of Mexico, (ii) initially remain within the eastern Gulf, but later may (iii) gain entry into currents that transport them into Atlantic waters.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/2138106
- Subject Headings
- Animal orientation, Magnetic fields, Sea turtles, Migration, Loggerhead turtle, Migration
- Format
- Document (PDF)