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- Title
- Wavelet de-noising applied to vibrational envelope analysis methods.
- Creator
- Bertot, Edward Max, Khoshgoftaar, Taghi M., Beaujean, Pierre-Philippe, Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
In the field of machine prognostics, vibration analysis is a proven method for detecting and diagnosing bearing faults in rotating machines. One popular method for interpreting vibration signals is envelope demodulation, which allows a technician to clearly identify an impulsive fault source and its severity. However incipient faults -faults in early stages - are masked by in-band noise, which can make the associated impulses difficult to detect and interpret. In this thesis, Wavelet De...
Show moreIn the field of machine prognostics, vibration analysis is a proven method for detecting and diagnosing bearing faults in rotating machines. One popular method for interpreting vibration signals is envelope demodulation, which allows a technician to clearly identify an impulsive fault source and its severity. However incipient faults -faults in early stages - are masked by in-band noise, which can make the associated impulses difficult to detect and interpret. In this thesis, Wavelet De-Noising (WDN) is implemented after envelope-demodulation to improve accuracy of bearing fault diagnostics. This contrasts the typical approach of de-noising as a preprocessing step. When manually measuring time-domain impulse amplitudes, the algorithm shows varying improvements in Signal-to-Noise Ratio (SNR) relative to background vibrational noise. A frequency-domain measure of SNR agrees with this result.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00004080, http://purl.flvc.org/fau/fd/FA00004080
- Subject Headings
- Fluid dynamics, Signal processing, Structural dynamics, Wavelet (Mathematics)
- Format
- Document (PDF)
- Title
- Calibration and Performance Evaluation for a Multiple Overlapping Field of View Serial Laser Imager.
- Creator
- Rasoletti, Nicholas, Beaujean, Pierre-Philippe, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
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The Combined Laser and Scan Sonar (CLASS) system is an extended range imaging system, incorporating both high-resolution laser images and high frequency sonar images. Both the laser and sonar images are collected simultaneously during testing to provide dual mode imagery of an underwater target, displaying both a 2D image of the target (laser image) and a 3D overlay of the target (sonar image). The laser component of the system is a Multiple Overlapping Field of view Serial Laser Imager ...
Show moreThe Combined Laser and Scan Sonar (CLASS) system is an extended range imaging system, incorporating both high-resolution laser images and high frequency sonar images. Both the laser and sonar images are collected simultaneously during testing to provide dual mode imagery of an underwater target, displaying both a 2D image of the target (laser image) and a 3D overlay of the target (sonar image). The laser component of the system is a Multiple Overlapping Field of view Serial Laser Imager (MOFSLI), capable of generating high-resolution sub-centimeter 2D images. MOFSLI generates the images by way of a near diffraction-limited 532 [nm] continuous wave (CW) laser beam being scanned over the target. Initial field tests resulted in high-quality images of the ocean floor, but also indicated the need for additional research on MOFSLI. In this thesis, we focus on the calibration of MOFSLI and on the evaluation of the image quality generated by this system, as a function of range, source power, receiver gain and water turbidity. This work was completed in the specialized underwater electrooptics testing facility located in the Ocean Visibility and Optics laboratory at Harbor Branch Oceanographic Institute (HBOI). Laboratory testing revealed the operational limits of the system, which functioned well until just beyond five attenuation lengths, where it becomes contrast limited due attenuation of target signal and the collection of non-image bearing backscattered photons. Testing also revealed the optimal settings of the system at given environmental conditions.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00004538, http://purl.flvc.org/fau/fd/FA00004538
- Subject Headings
- Electrooptics, Inertial navigation systems, Lasers -- Measurement -- Evaluation, Light -- Scattering
- Format
- Document (PDF)
- Title
- Characterizing the Magnetic Signature of Internal Waves.
- Creator
- Nieves, Eric, Beaujean, Pierre-Philippe, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
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This study is performed in tandem with numerous experiments performed by the U.S. Navy to characterize the ocean environment in the South Florida region. The research performed in this study includes signal processing steps for isolating ocean phenomena, such as internal waves, in the magnetic field. Raw magnetometer signals, one on shore and one underwater, are processed and removed of common distortions. They are then run through a series of filtering techniques, including frequency domain...
Show moreThis study is performed in tandem with numerous experiments performed by the U.S. Navy to characterize the ocean environment in the South Florida region. The research performed in this study includes signal processing steps for isolating ocean phenomena, such as internal waves, in the magnetic field. Raw magnetometer signals, one on shore and one underwater, are processed and removed of common distortions. They are then run through a series of filtering techniques, including frequency domain cancellation (FDC). The results of the filtered magnetic residual are compared to similarly processed Acoustic Doppler Current Profiler (ADCP) data to correlate whether a magnetic signature is caused by ocean phenomena.
Show less - Date Issued
- 2017
- PURL
- http://purl.flvc.org/fau/fd/FA00004917, http://purl.flvc.org/fau/fd/FA00004917
- Subject Headings
- Ocean currents--Measurement., Adaptive signal processing., Wave-motion, Theory of., Wavelets (Mathematics)
- 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
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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.
Show less - 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
- APPLYING BLIND SOURCE SEPARATION TO MAGNETIC ANOMALY DETECTION.
- Creator
- Nieves, Eric, 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 research shows a novel approach for the Magnetic Anomaly Differentiation and Localization Algorithm, which simultaneously localizes multiple magnetic anomalies with weak total field signatures (tens of nT). In particular, it focuses on the case where there are two homogeneous targets with known magnetic moments. This was done by analyzing the magnetic signals and adapting Independent Component Analysis (ICA) and Simulated Annealing (SA) to solve the problem statement. The results show the...
Show moreThe research shows a novel approach for the Magnetic Anomaly Differentiation and Localization Algorithm, which simultaneously localizes multiple magnetic anomalies with weak total field signatures (tens of nT). In particular, it focuses on the case where there are two homogeneous targets with known magnetic moments. This was done by analyzing the magnetic signals and adapting Independent Component Analysis (ICA) and Simulated Annealing (SA) to solve the problem statement. The results show the groundwork for using a combination of fastICA and SA to give localization errors of 3 meters or less per target in simulation and achieved a 58% success rate. Experimental results experienced additional errors due to the effects of magnetic background, unknown magnetic moments, and navigation error. While one target was localized within 3 meters, only the latest experimental run showed the second target approaching the localization specification. This highlighted the need for higher signal-to-noise ratio and equipment with better navigational accuracy. The data analysis was used to provide recommendations on the needed equipment to minimize observed errors and improve algorithm success.
Show less - Date Issued
- 2020
- PURL
- http://purl.flvc.org/fau/fd/FA00013610
- Subject Headings
- Magnetic anomalies, Simulated annealing (Mathematics), Independent component analysis, Unmanned vehicles
- Format
- Document (PDF)
- Title
- APPLICATION OF SIGNAL DECOMPOSITION TO IMPROVE TIME DELAY ESTIMATES FOR SYNTHETIC APERTURE SONAR MOTION COMPENSATION.
- Creator
- Gazagnaire, Julia, Beaujean, Pierre-Philippe, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
Synthetic Aperture Sonar (SAS) provides the best opportunity for side-looking sonar mounted on underwater platforms to achieve high-resolution images. However, SAS processing requires strict constraints on resolvable platform motion. The most common approach to estimate this motion is to use the Redundant Phase Center (RPC) technique. Here the ping interval is set, such that a portion of the sonar array overlaps as the sensor moves forward. The time delay between the pings received on these...
Show moreSynthetic Aperture Sonar (SAS) provides the best opportunity for side-looking sonar mounted on underwater platforms to achieve high-resolution images. However, SAS processing requires strict constraints on resolvable platform motion. The most common approach to estimate this motion is to use the Redundant Phase Center (RPC) technique. Here the ping interval is set, such that a portion of the sonar array overlaps as the sensor moves forward. The time delay between the pings received on these overlapping elements is estimated using cross-correlation. These time delays are then used to infer the pingto-ping vehicle motion. Given the stochastic nature of the operational environment, some level of decorrelation between these two signals is likely. In this research, two iterative signal decomposition methods well suited for nonlinear and non-stationary signals, are investigated for their potential to improve the Time Delay Estimation (TDE). The first of this type, the Empirical Mode Decomposition (EMD) was introduced by Huang in the seminal paper, The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis and is the foundation for the algorithms used in this research. This method decomposes a signal into a finite sequence of simple components termed Intrinsic Mode Functions (IMFs). The Iterative Filter (IF) approach, developed by Lin, Wang and Zhou, builds on the EMD framework. The sonar signals considered in this research are complex baseband signals. Both the IF and EMD algorithms were designed to decompose real signals. However, the IF variant, the Multivariate Fast Iterative Filtering (MFIF) Algorithm, developed by Cicone, and the EMD variant, the Fast and Adaptive Multivariate Empirical Mode Decomposition (FAMVEMD) algorithm, developed by Thirumalaisamy and Ansell, preserve both the magnitude and phase in the decomposition and hence were chosen for this analysis.
Show less - Date Issued
- 2021
- PURL
- http://purl.flvc.org/fau/fd/FA00013795
- Subject Headings
- Sonar, Signal processing, Synthetic apertures
- Format
- Document (PDF)
- Title
- Underwater acoustic channel estimation using multiple sources and receivers in shallow waters at very-high frequencies.
- Creator
- Kaddouri, Samar, Beaujean, Pierre-Philippe, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The underwater channel poses numerous challenges for acoustic communication. Acoustic waves suffer long propagation delay, multipath, fading, and potentially high spatial and temporal variability. In addition, there is no typical underwater acoustic channel; every body of water exhibits quantifiably different properties. Underwater acoustic modems are traditionally operated at low frequencies. However, the use of broadband, high frequency communication is a good alternative because of the...
Show moreThe underwater channel poses numerous challenges for acoustic communication. Acoustic waves suffer long propagation delay, multipath, fading, and potentially high spatial and temporal variability. In addition, there is no typical underwater acoustic channel; every body of water exhibits quantifiably different properties. Underwater acoustic modems are traditionally operated at low frequencies. However, the use of broadband, high frequency communication is a good alternative because of the lower background noise compared to low-frequencies, considerably larger bandwidth and better source transducer efficiency. One of the biggest problems in the underwater acoustic communications at high frequencies is time-selective fading, resulting in the Doppler spread. While many Doppler detection, estimation and compensation techniques can be found in literature, the applications are limited to systems operating at low frequencies contained within frequencies ranging from a few hundred Hertz to around 30 kHz.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00004384, http://purl.flvc.org/fau/fd/FA00004384
- Subject Headings
- Adaptive signal processing, MIMO systems, Signal processing -- Ditigal techniques -- Mathematics, Underwater acoustic telemetry, Underwater acoustics -- Evaluation, Wireless communication systems
- Format
- Document (PDF)
- Title
- A Study of the Underwater Acoustic Propagation in a Turning Basin Modeled as a Three-Dimensional Duct Closed at One End Using the Method of Images.
- Creator
- Staska, Matthew D., Beaujean, Pierre-Philippe, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A computer-efficient model of the underwater acoustic propagation m a shallow, three-dimensional duct closed at one end has been developed using the method of images. Presented in this research is the development of this three-dimensional method of images analysis for a rectangular duct. Using this analysis, a model of the impulse response of the acoustic channel is constructed. Also presented in this work is the actual impulse response collected during field experimentation in the south...
Show moreA computer-efficient model of the underwater acoustic propagation m a shallow, three-dimensional duct closed at one end has been developed using the method of images. Presented in this research is the development of this three-dimensional method of images analysis for a rectangular duct. Using this analysis, a model of the impulse response of the acoustic channel is constructed. Also presented in this work is the actual impulse response collected during field experimentation in the south turning basin of Port Everglades in Fort Lauderdale, Florida. The results demonstrate that the impulse response is modeled with a relative echo magnitude error of 1.62 dB at worst, and a relative echo location error varying between 0% and 4% when averaged across multiple measurements and sensor locations.
Show less - Date Issued
- 2007
- PURL
- http://purl.flvc.org/fau/fd/FA00012557
- Subject Headings
- Underwater acoustics--Measurement, Wave motion, Theory of, Wave equation--Numerical solutions, Sound-waves--Transmission--Mathematical models
- Format
- Document (PDF)
- Title
- Mobile docking of REMUS-100 equipped with USBL-APS to an unmanned surface vehicle: a performance feasibility study.
- Creator
- Miranda, Mario II, Beaujean, Pierre-Philippe, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The overall objective of this work is to evaluate the ability of homing and docking an unmanned underwater vehicle (Hydroid REMUS 100 UUV) to a moving unmanned surface vehicle (Wave-Adaptive Modular Surface Vehicle USV) using a Hydroid Digital Ultra-Short Baseline (DUSBL) acoustic positioning system (APS), as a primary navigation source. An understanding of how the UUV can rendezvous with a stationary USV first is presented, then followed by a moving USV. Inherently, the DUSBL-APS is...
Show moreThe overall objective of this work is to evaluate the ability of homing and docking an unmanned underwater vehicle (Hydroid REMUS 100 UUV) to a moving unmanned surface vehicle (Wave-Adaptive Modular Surface Vehicle USV) using a Hydroid Digital Ultra-Short Baseline (DUSBL) acoustic positioning system (APS), as a primary navigation source. An understanding of how the UUV can rendezvous with a stationary USV first is presented, then followed by a moving USV. Inherently, the DUSBL-APS is susceptible to error due to the physical phenomena of the underwater acoustic channel (e.g. ambient noise, attenuation and ray refraction). The development of an APS model has allowed the authors to forecast the UUV’s position and the estimated track line of the USV as determined by the DUSBL acoustic sensor. In this model, focus is placed on three main elements: 1) the acoustic channel and sound ray refraction when propagating in an in-homogeneous medium; 2) the detection component of an ideal DUSBL-APS using the Neyman-Pearson criterion; 3) the signal-to-noise ratio (SNR) and receiver directivity impact on position estimation. The simulation tool is compared against actual open water homing results in terms of the estimated source position between the simulated and the actual USBL range and bearing information.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00004140, http://purl.flvc.org/fau/fd/FA00004140
- Subject Headings
- Adaptive signal processing, Mobile robots, Underwater acoustic telemetry
- Format
- Document (PDF)
- Title
- Performance and limitations of acoustic positioning using a tetrahedral ultra-short baseline array and an acoustic modem source transmitting frequency-hopped sequences.
- Creator
- Mohamed, Asif I., Florida Atlantic University, Beaujean, Pierre-Philippe, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The operation of unmanned underwater vehicles requires communications with other nearby vehicles as well as accurate positioning to prevent duplication of work, collisions and other mishaps. This thesis details the integration of an ultra-short baseline positioning system with four transducers arranged as a tetrahedron for use with the FAU Dual Purpose Acoustic Modem. The source position is estimated by processing coherently a series of frequency-hopped pulses to obtain a set of bearings,...
Show moreThe operation of unmanned underwater vehicles requires communications with other nearby vehicles as well as accurate positioning to prevent duplication of work, collisions and other mishaps. This thesis details the integration of an ultra-short baseline positioning system with four transducers arranged as a tetrahedron for use with the FAU Dual Purpose Acoustic Modem. The source position is estimated by processing coherently a series of frequency-hopped pulses to obtain a set of bearings, optimally combined through maximum likelihood estimation of the azimuth and elevation. A simulation has been implemented and experiments have been performed in a calibration tank. Model and experiments confirm that the accuracy of this system improves with the number of pulses and the signal-to-noise ratio. A mean positional error of 5.51% can be obtained with an SNR of 20 dB and a single processed pulse, the error decreases to 2.84% using six processed pulses.
Show less - Date Issued
- 2006
- PURL
- http://purl.flvc.org/fcla/dt/13412
- Subject Headings
- Underwater navigation, Remote submersibles, Computer integrated manufacturing systems, Acoustical engineering, Underwater acoustics--Instruments
- Format
- Document (PDF)
- Title
- Maximum likelihood estimates of azimuth and elevation for a frequency-hopped active source using a tetrahedral ultra-short baseline.
- Creator
- Warin, Raphael., Florida Atlantic University, Beaujean, Pierre-Philippe, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Ultra-Short-BaseLine (USBL) is the most practical underwater acoustic positioning system for autonomous underwater vehicles because of its small space requirement. The objective of this research is to develop a USBL system capable of estimating a source location transmitting frequency-hopped tones sequences. Such sequences are characteristic of spread spectrum signaling used in underwater acoustic communication network. It must be able to provide azimuth and elevation of a modem-type source...
Show moreUltra-Short-BaseLine (USBL) is the most practical underwater acoustic positioning system for autonomous underwater vehicles because of its small space requirement. The objective of this research is to develop a USBL system capable of estimating a source location transmitting frequency-hopped tones sequences. Such sequences are characteristic of spread spectrum signaling used in underwater acoustic communication network. It must be able to provide azimuth and elevation of a modem-type source with an accuracy of 0.3 degrees; for both angles using the synchronization stage of the transmission. The acoustic antenna is composed of four transducers arranged as a tetrahedron. Using the model of Quazi and Lerro, which provides an expression for the variance of the bearing angle, azimuth and elevation of the transmitter are estimated employing maximum likelihood estimation. This system is simulated, tested and calibrated in a tank. Simulated results satisfy the requirement with a SNR of 32dB and 8 symbols. The latest experimental measurements present an accuracy of 3 degrees.
Show less - Date Issued
- 2004
- PURL
- http://purl.flvc.org/fcla/dt/13135
- Subject Headings
- Underwater acoustics--Instruments, Underwater acoustic telemetry, Signal processing--Technique, Adaptive signal processing
- Format
- Document (PDF)
- Title
- High-speed acoustic communication in shallow water using spatio-temporal adaptive array processing.
- Creator
- Beaujean, Pierre-Philippe, Florida Atlantic University, LeBlanc, Lester R., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A novel method of achieving stable high-speed underwater acoustic communication with a fairly low-complexity of implementation is proposed. The proposed approach is to split the space and time processing into two separate sub-optimal processes. As a result, processing complexity is significantly reduced and the instabilities associated with large tap vectors at large time-frequency spread products are reduced. The proposed space-time signal processing method utilizes a different beamformer...
Show moreA novel method of achieving stable high-speed underwater acoustic communication with a fairly low-complexity of implementation is proposed. The proposed approach is to split the space and time processing into two separate sub-optimal processes. As a result, processing complexity is significantly reduced and the instabilities associated with large tap vectors at large time-frequency spread products are reduced. The proposed space-time signal processing method utilizes a different beamformer optimization strategy compared to the time domain optimization strategy. This allows to separately adjust the adaptation parameters for the spatial and temporal characteristics of the signal, which have vastly different requirements. The time domain signal is subject to variations in phase that require rapid filter updates whereas the directional characteristics of the signal do not vary appreciably over the message length and do not require a rapid adaptation response. The proposed method allows for high-speed underwater acoustic communication in very shallow water using coherent modulation techniques, and offers a series of unique features: significant reduction of the signal-to-noise and interference ratio (SNIR), improvement of the bandwidth efficiency by reduction of the forward-error coding redundancy requirements, real-time evaluation of the time-spread by Doppler spread product (BL) and channel stability estimate. Experimental results demonstrate that stable acoustic communication can be achieved at rates of 32000 bits per second at a distance of 3 km, in 40 feet of water and in sea-state 2 conditions. Fast and slow fading properties of the channel are measured, as the BL product can vary by a decade in 116 ms, and by two decades within minutes, from 0.001 to 0.1. The real-time analysis shows a strong correlation between time spread, Doppler spread, spatial coherence of the acoustic channel and communication performance. Overall, this research provides more scientific and experimental ground to understand the limitations of multi-channel adaptive receiver techniques in terms of stability, hardware requirements and channel tracking capability.
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/11952
- Subject Headings
- Underwater acoustic telemetry, Adaptive signal processing
- 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
-
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
- ESTIMATION OF THE PHYSICAL PROPERTIES OF CORRODING REBAR IN REINFORCED CONCRETE USING BIOT-STOLL MODEL INVERSION.
- Creator
- Brogden, Matthew, Beaujean, Pierre-Philippe, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
The detection of rebar corrosion in reinforced concrete is important due to the high costs of corrosion related damages to infrastructure. One such method of rebar corrosion lies in the use of non-destructive ultrasonic testing. To date, acoustic methods require either the training of an artificial neural network or a theory of acoustic wave propagation. Using a more complete acoustic model such as the Biot-Stoll model avoids algorithm training requirements by directly modeling the acoustic...
Show moreThe detection of rebar corrosion in reinforced concrete is important due to the high costs of corrosion related damages to infrastructure. One such method of rebar corrosion lies in the use of non-destructive ultrasonic testing. To date, acoustic methods require either the training of an artificial neural network or a theory of acoustic wave propagation. Using a more complete acoustic model such as the Biot-Stoll model avoids algorithm training requirements by directly modeling the acoustic environment. A problem with this method lies in the complexity of the model and the selection of free parameters. The problem of parameter selection is addressed by a series of targeted measurements using ultrasonic transducers on a set of existing reinforced concrete samples placed in a saltwater solution. This data can then be analyzed by a non-linear least squares solver to produce a better fit for the acoustic signal.
Show less - Date Issued
- 2022
- PURL
- http://purl.flvc.org/fau/fd/FA00014032
- Subject Headings
- Reinforcing bars--Corrosion, Reinforced concrete, Acoustics, Ultrasonics
- Format
- Document (PDF)
- Title
- Optimized Parameters Fitting of a Poro-Elastic Acoustic Model with Ultrasonic Measurements for the Monitoring of Corroding Rebar in Reinforced Concrete.
- Creator
- Shaffer, Samuel, Beaujean, Pierre-Philippe, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
Traditional techniques of observing cracking within reinforced structures can be invasive, leading to an increased risk of added corrosion to structures already undergoing corrosive processes. The research presented in this document improves upon a nondestructive method for detecting early crack formation in reinforced concrete. This method includes using acoustic signaling to add a layer of salt water between the sensor and analyzed sample. Following the collection of surface and rebar echo...
Show moreTraditional techniques of observing cracking within reinforced structures can be invasive, leading to an increased risk of added corrosion to structures already undergoing corrosive processes. The research presented in this document improves upon a nondestructive method for detecting early crack formation in reinforced concrete. This method includes using acoustic signaling to add a layer of salt water between the sensor and analyzed sample. Following the collection of surface and rebar echo responses, an adapted version of the novel Biot-Stoll method is used to model sound propagation for poro-elastic mediums. Testing of model parameters and variables has improved the root mean square error (RMSE) by up to 63.7% when studying the full signal, and up to 62.6% for the rebar echo locations. These improvements signify better curve fitting between simulated and measured responses, which lead to increased accuracy in the model parameter outputs.
Show less - Date Issued
- 2023
- PURL
- http://purl.flvc.org/fau/fd/FA00014265
- Subject Headings
- Reinforced concrete, Reinforcing bars--Corrosion, Ultrasonic testing
- 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
- 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
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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
- Motion Compensation of an Ultra Short Baseline Array for the Acoustic Positioning of an Underwater Vehicle for Port Operations.
- Creator
- Bon, Antoine, Beaujean, Pierre-Philippe, Florida Atlantic University
- Abstract/Description
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A Motion Compensated (MC) Ultra Short Baseline (USBL) Acoustic Positioning System (APS) operable in shallow water and port environment has been implemented at Florida Atlantic University. Multi-tones signal modulation and log-likelihood maximization enable this APS to operate in volumes of water of less than 10 cubic meters. Standard deviations of the acoustic source elevation and azimuth estimates were computed to be 3 degrees in an 8 cubic meters test tank, and reduce to 0.9 degree in a 2...
Show moreA Motion Compensated (MC) Ultra Short Baseline (USBL) Acoustic Positioning System (APS) operable in shallow water and port environment has been implemented at Florida Atlantic University. Multi-tones signal modulation and log-likelihood maximization enable this APS to operate in volumes of water of less than 10 cubic meters. Standard deviations of the acoustic source elevation and azimuth estimates were computed to be 3 degrees in an 8 cubic meters test tank, and reduce to 0.9 degree in a 2 meters deep marina. The motion compensating system estimates the array position and orientation while merging noisy measurements from a Magnetic, Angular Rate, and Gravity (MARG) sensor and a Differential Global Positioning System (DGPS) using Kalman filters. Experiments show 0.67 and 2.67 degrees of error for the array tilt and heading estimates, and 0.74 meter for the array position estimate.
Show less - Date Issued
- 2007
- PURL
- http://purl.flvc.org/fau/fd/FA00012507
- Subject Headings
- Underwater navigation, Acoustical engineering, Adaptive signal processing, Underwater acoustic telemetry
- Format
- Document (PDF)
- Title
- Sediment classification of the sea floor using the Chirp Sonar and the Biot model.
- Creator
- Beaujean, Pierre-Philippe, Florida Atlantic University, LeBlanc, Lester R.
- Abstract/Description
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A new method is proposed to infer the geotechnical properties of the sea floor from its response to the frequency-modulated pulses emitted by the subbottom profiler called Chirp Sonar. The environment is assumed to be a multilayered medium, composed of homogeneous layers, or an inhomogeneous half-space with depth-dependent properties. The acoustic response of the sediment is computed using the Biot-Stoll theory. The Levenberg-Marquardt method is applied to fit the synthetic response to the...
Show moreA new method is proposed to infer the geotechnical properties of the sea floor from its response to the frequency-modulated pulses emitted by the subbottom profiler called Chirp Sonar. The environment is assumed to be a multilayered medium, composed of homogeneous layers, or an inhomogeneous half-space with depth-dependent properties. The acoustic response of the sediment is computed using the Biot-Stoll theory. The Levenberg-Marquardt method is applied to fit the synthetic response to the experimental response of an homogeneous layer overlying the sea floor. The porosity, the permeability, the mean grain diameter, the mass density, the bulk modulus and the shear modulus within this sediment layer can be estimated. A multilayered medium with depth-dependent properties could be applied to this inversion technique in the future.
Show less - Date Issued
- 1995
- PURL
- http://purl.flvc.org/fcla/dt/15208
- Subject Headings
- Marine sediments--Acoustic properties, Underwater acoustics--Measurement, Ocean bottom, Sonar
- Format
- Document (PDF)
- Title
- An investigation of the influence of surface roughness on reflection coefficients measured by a chirp sonar using a laser profiling of the seafloor.
- Creator
- Hache, Nicolas., Florida Atlantic University, Beaujean, Pierre-Philippe, Schock, Steven G.
- Abstract/Description
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This research investigates the validity of an acoustic propagation model by comparing theoretical reflection coefficients, function of frequency, to FAU chirp sonar measurements (chirp sub-bottom profiler). An acoustic model has been implemented to estimate the spectrum of energy reflected from sandy sediments in the presence of surface scattering. The surface roughness being the dominant reverberation part, the volume scattering has been neglected in this model. A laser scanning system...
Show moreThis research investigates the validity of an acoustic propagation model by comparing theoretical reflection coefficients, function of frequency, to FAU chirp sonar measurements (chirp sub-bottom profiler). An acoustic model has been implemented to estimate the spectrum of energy reflected from sandy sediments in the presence of surface scattering. The surface roughness being the dominant reverberation part, the volume scattering has been neglected in this model. A laser scanning system involving an image-processing algorithm has been designed to measure the seafloor bottom roughness using 1D Fourier transforms. In the case of anisotropic roughness, an estimation of the sand ripples dominant direction is provided involving 2D Fourier transforms. Measurements of acoustic data using a chirp sonar and estimation of bottom roughness from video data of the scanner over an artificial bottom are provided to compare the reflection coefficients obtained from the data actually measured with those from the acoustical model.
Show less - Date Issued
- 2005
- PURL
- http://purl.flvc.org/fcla/dt/13212
- Subject Headings
- Underwater acoustics--Measurement, Marine sediments--Acoustic properties, Oceanography, Seawater--Acoustic properties
- Format
- Document (PDF)