Experimental evidence suggests that the ambient acoustic noise in the Arctic Ocean below the marg... more Experimental evidence suggests that the ambient acoustic noise in the Arctic Ocean below the marginal ice zone (MIZ) is generated by the clashing of ice floes on the sea surface. The noise is spiky in character, with a spectral density over the frequency range from 50 Hz to 1 kHz which varies with frequency as f -n , where the index n varies slowly with time, showing an average value approximately equal to 2. Over a period of five days or so, n was observed to vary between a low value of 1.0 and a high value of 3.0. A theoretical model of the MIZ ambient noise is presented, based on a floe/floe collision mechanism, which predicts time series and spectra whose features are broadly consistent with those observed in the data.
The 3-D effect on underwater~ustic propagation due to timuthal variation of bottom topography is ... more The 3-D effect on underwater~ustic propagation due to timuthal variation of bottom topography is studied fw offshore regions southwest of Taiwm, which submarine myon are known to exist. The mustic propagation is studied numerically using the FOR3D code and via field experiment. Results show that 3-D effect to be more profound along the axis of the canyon than across it. The calculation is proved to wee well with field% which indicates 3-D effed on acoustic propagation exists in the real~environment. mODUC~ON Lately 3-D effe~s on underwater amstic propagation have been frequently reported (1). The major muses for the 3
Nonlinear internal waves (NLIWs) became elevation waves were measured on the South China Sea cont... more Nonlinear internal waves (NLIWs) became elevation waves were measured on the South China Sea continental shelf. This paper presents the noises generated from the sea surface breaking waves in the convergent areas behind the wave trough of the elevation waves. The acoustic data were collected by the vertical line array (VLA) with 16 hydrophones in depths of 42-121 m. Both of internal wave forms and arrival time were estimated by the evidence of sea currents (ADCP) and temperatures, which were compared with noise levels. The depth-independent noise levels suggest the noise fields impacted by NLIWs. In the NLIWs passed duration, the noise fields were dominated by the overhead noises of the VLA that arose the noise levels over 3 dB and caused the noise levels to decrease with increasing depths. This characteristic from the analysis results provide to identify the noises were fundamentally generated from the NLIWs. Moreover, the raised noise levels and changed duration of noise levels we...
Journal of The Acoustical Society of America, 2001
An equivalent transform method for evaluating the effect of water column mismatch on geoacoustic ... more An equivalent transform method for evaluating the effect of water column mismatch on geoacoustic inversion is presented. This quantitative method is derived from perturbative inverse formulations and gives a quantitative way to evaluate how the water column mismatch error transfers into the bottom inversion results. In this paper, this method is illustrated with two test cases, in which linear and
Journal of The Acoustical Society of America, 2001
Although ambient noise has been an object of study for a long time, there is little modeling done... more Although ambient noise has been an object of study for a long time, there is little modeling done for real ocean environment to reflect oceanographic changes. The numerical simulation in this study is based on PE code, with environmental and bathymetry data from the 2001 ASIAEX SCS experiment. Simple sources were distributed near sea surface in the model, and source
Recent research has shown the evolutions of internal tides and nonlinear internal waves in costal... more Recent research has shown the evolutions of internal tides and nonlinear internal waves in costal region in the South China Seas (SCS). Depression waves were observed on the slope and shelf region in Asian Seas International Acoustics Experiment (ASIAEX) SCS experiment. The propagating internal waves (or tides) would cause acoustic mode coupling and result in intensity fluctuations or arrival pattern
Journal of The Acoustical Society of America, 2001
In predicting wave propagation, the size of the angle of propagation plays an important role; thu... more In predicting wave propagation, the size of the angle of propagation plays an important role; thus, the concept of wide angle is introduced. Most existing acoustic propagation prediction models do have the capability of treating the wide angle but the treatment, in practice, is vertical propagation angle. This is desirable for solving 2D (r-z) problems. Typically, 3D problems are dealt
In the past few decades the elastic properties of ocean bottom were usually ignored to simplify p... more In the past few decades the elastic properties of ocean bottom were usually ignored to simplify problems by assuming a fluid seabed. Nevertheless, while it is acceptable to make such assumptions in deep water, the effects of shear waves can never be omitted as long as sound waves penetrates into ocean bottom, especially in shallow water where interactions between sound
Journal of The Acoustical Society of America, 2002
A three-dimensional ocean environment is generated using measured ocean data from the ASIAEX Sout... more A three-dimensional ocean environment is generated using measured ocean data from the ASIAEX South China Sea experiment. The experiment site is characterized as an active internal tide/solibore propagation region along the Northwestern shelf break of the South China Sea. The three-dimensional acoustic effects are studied using a wide-angle version of the parabolic equation code for3d. Mode coupling matrices and horizontal
In this paper, we quantify the dynamical causes and uncertainties of striking differences in acou... more In this paper, we quantify the dynamical causes and uncertainties of striking differences in acoustic transmission data collected on the shelf and shelfbreak in the northeastern Taiwan region within the context of the 2008 Quantifying, Predicting, and Exploiting Uncertainty (QPE 2008) pilot experiment. To do so, we employ our coupled oceanographic (4-D) and acoustic (Nx2-D) modeling systems with ocean data
Passive-phase conjugation (PPC), in a shallow water waveguide, the cross-correlation of impulse r... more Passive-phase conjugation (PPC), in a shallow water waveguide, the cross-correlation of impulse response and the impulse response immediately after, can be utilized as the channel equalizer to enhance the communication performance. PPC is more practical and simpler than Time Reversal Mirror (TRM) since the back propagation is simulated, instead of using source receiver array transmitting backward. This paper addresses the
Journal of The Acoustical Society of America, 2001
Sonar performance can be characterized by its detection range, which is determined by the sonar e... more Sonar performance can be characterized by its detection range, which is determined by the sonar equation. The sonar equation includes parameters of sonar systems, environments, and the detection algorithms. Though the detection algorithm is itself a statistical means, it does not describe the relationship between the statistical properties of the environmental parameters with the detection range. This paper presents a
The developments of marine observatories and automatic sound detection algorithms have facilitate... more The developments of marine observatories and automatic sound detection algorithms have facilitated the long-term monitoring of multiple species of odontocetes. Although classification remains difficult, information on tonal sound in odontocetes (i.e., toothed whales, including dolphins and porpoises) can provide insights into the species composition and group behavior of these species. However, the approach to measure whistle contour parameters for detecting the variability of odontocete vocal behavior may be biased when the signal-tonoise ratio is low. Thus, methods for analyzing the whistle usage of an entire group are necessary. In this study, a local-max detector was used to detect burst pulses and representative frequencies of whistles within 4.5-48 kHz. Whistle contours were extracted and classified using an unsupervised method. Whistle characteristics and usage pattern were quantified based on the distribution of representative frequencies and the composition of whistle repertoires. Based on the one year recordings collected from the Marine Cable Hosted Observatory off northeastern Taiwan, odontocete burst pulses and whistles were primarily detected during the nighttime, especially after sunset. Whistle usage during the nighttime was more complex, and whistles with higher frequency were mainly detected during summer and fall. According to the multivariate analysis, the diurnal variation of whistle usage was primarily related to the change of mode frequency, diversity of representative frequency, and sequence complexity. The seasonal variation of whistle usage involved the previous three parameters, in addition to the diversity of whistle clusters. Our results indicated that the species and behavioral composition of the local odontocete community may vary among seasonal and diurnal cycles. The current monitoring platform facilitates the evaluation of whistle usage based on group behavior and provides feature vectors for species and behavioral classification in future studies.
Theoretical and Computational Acoustics 2005 - Proceedings of the 7th International Conference on ICTCA 2005, 2006
A numerical code using Gaussian Beam Model (NTUGBM) is developed for underwater acoustic propagat... more A numerical code using Gaussian Beam Model (NTUGBM) is developed for underwater acoustic propagation at high frequency (larger than 1 kHz) in oceans with penetrating slope bottom. Several test cases are used to benchmark NTUGBM. Cases include continental shelf and continental slope. The results of NTUGBM are compared with results using EFEPE and FOR3D (Nx2D version). Results of NTUGBM agree
Data analysis and 3D numerical simulations of the acoustic propagation in the ASIAEX SCS experime... more Data analysis and 3D numerical simulations of the acoustic propagation in the ASIAEX SCS experiment are presented in this paper. During the experiment personnel aboard the Taiwanese ocean research vessel, OR3, periodically deployed and towed the J-15-3 acoustic source to study the sound propagation in the ocean. One of the emitted waveforms was continuous wave (CW), which had 5 simultaneous
Background: Zebrafish skin is composed of enveloping and basal layers which form a first-line def... more Background: Zebrafish skin is composed of enveloping and basal layers which form a first-line defense system against pathogens. Zebrafish epidermis contains ionocytes and mucous cells that aid secretion of acid/ions or mucous through skin. Previous studies demonstrated that fish skin is extremely sensitive to external stimuli. However, little is known about the molecular mechanisms that modulate skin cell apoptosis in zebrafish.
Background: Obesity is a complex, multifactorial disorder influenced by the interaction of geneti... more Background: Obesity is a complex, multifactorial disorder influenced by the interaction of genetic, epigenetic, and environmental factors. Obesity increases the risk of contracting many chronic diseases or metabolic syndrome. Researchers have established several mammalian models of obesity to study its underlying mechanism. However, a lower vertebrate model for conveniently performing drug screening against obesity remains elusive. The specific aim of this study was to create a zebrafish obesity model by over expressing the insulin signaling hub of the Akt1 gene.
This document describes data, sensors, and other useful information pertaining to the ONR sponsor... more This document describes data, sensors, and other useful information pertaining to the ONR sponsored QPE field program to quantify, predict and exploit uncertainty in observations and prediction of sound propagation. This experiment was a joint operation between Taiwanese and U.S. researchers to measure and assess uncertainty of predictions of acoustic transmission loss and ambient noise, and to observe the physical oceanography and geology that are necessary to improve their predictability. This work was performed over the continental shelf and slope northeast of Taiwan at two sites: one that was a relatively flat, homogeneous shelf region and a more complex geological site just shoreward of the shelfbreak that was influenced by the proximity of the Kuroshio Current. Environmental moorings and ADCP moorings were deployed and a shipboard SeaSoar vehicle was used to measure environmental spatial structure. In addition, multiple bottom moored receivers and a horizontal hydrophone array were deployed to sample transmission loss from a mobile source and ambient noise. The acoustic sensors, environmental sensors, shipboard resources, and experiment design, and their data, are presented and described in this technical report.
Experimental evidence suggests that the ambient acoustic noise in the Arctic Ocean below the marg... more Experimental evidence suggests that the ambient acoustic noise in the Arctic Ocean below the marginal ice zone (MIZ) is generated by the clashing of ice floes on the sea surface. The noise is spiky in character, with a spectral density over the frequency range from 50 Hz to 1 kHz which varies with frequency as f -n , where the index n varies slowly with time, showing an average value approximately equal to 2. Over a period of five days or so, n was observed to vary between a low value of 1.0 and a high value of 3.0. A theoretical model of the MIZ ambient noise is presented, based on a floe/floe collision mechanism, which predicts time series and spectra whose features are broadly consistent with those observed in the data.
The 3-D effect on underwater~ustic propagation due to timuthal variation of bottom topography is ... more The 3-D effect on underwater~ustic propagation due to timuthal variation of bottom topography is studied fw offshore regions southwest of Taiwm, which submarine myon are known to exist. The mustic propagation is studied numerically using the FOR3D code and via field experiment. Results show that 3-D effect to be more profound along the axis of the canyon than across it. The calculation is proved to wee well with field% which indicates 3-D effed on acoustic propagation exists in the real~environment. mODUC~ON Lately 3-D effe~s on underwater amstic propagation have been frequently reported (1). The major muses for the 3
Nonlinear internal waves (NLIWs) became elevation waves were measured on the South China Sea cont... more Nonlinear internal waves (NLIWs) became elevation waves were measured on the South China Sea continental shelf. This paper presents the noises generated from the sea surface breaking waves in the convergent areas behind the wave trough of the elevation waves. The acoustic data were collected by the vertical line array (VLA) with 16 hydrophones in depths of 42-121 m. Both of internal wave forms and arrival time were estimated by the evidence of sea currents (ADCP) and temperatures, which were compared with noise levels. The depth-independent noise levels suggest the noise fields impacted by NLIWs. In the NLIWs passed duration, the noise fields were dominated by the overhead noises of the VLA that arose the noise levels over 3 dB and caused the noise levels to decrease with increasing depths. This characteristic from the analysis results provide to identify the noises were fundamentally generated from the NLIWs. Moreover, the raised noise levels and changed duration of noise levels we...
Journal of The Acoustical Society of America, 2001
An equivalent transform method for evaluating the effect of water column mismatch on geoacoustic ... more An equivalent transform method for evaluating the effect of water column mismatch on geoacoustic inversion is presented. This quantitative method is derived from perturbative inverse formulations and gives a quantitative way to evaluate how the water column mismatch error transfers into the bottom inversion results. In this paper, this method is illustrated with two test cases, in which linear and
Journal of The Acoustical Society of America, 2001
Although ambient noise has been an object of study for a long time, there is little modeling done... more Although ambient noise has been an object of study for a long time, there is little modeling done for real ocean environment to reflect oceanographic changes. The numerical simulation in this study is based on PE code, with environmental and bathymetry data from the 2001 ASIAEX SCS experiment. Simple sources were distributed near sea surface in the model, and source
Recent research has shown the evolutions of internal tides and nonlinear internal waves in costal... more Recent research has shown the evolutions of internal tides and nonlinear internal waves in costal region in the South China Seas (SCS). Depression waves were observed on the slope and shelf region in Asian Seas International Acoustics Experiment (ASIAEX) SCS experiment. The propagating internal waves (or tides) would cause acoustic mode coupling and result in intensity fluctuations or arrival pattern
Journal of The Acoustical Society of America, 2001
In predicting wave propagation, the size of the angle of propagation plays an important role; thu... more In predicting wave propagation, the size of the angle of propagation plays an important role; thus, the concept of wide angle is introduced. Most existing acoustic propagation prediction models do have the capability of treating the wide angle but the treatment, in practice, is vertical propagation angle. This is desirable for solving 2D (r-z) problems. Typically, 3D problems are dealt
In the past few decades the elastic properties of ocean bottom were usually ignored to simplify p... more In the past few decades the elastic properties of ocean bottom were usually ignored to simplify problems by assuming a fluid seabed. Nevertheless, while it is acceptable to make such assumptions in deep water, the effects of shear waves can never be omitted as long as sound waves penetrates into ocean bottom, especially in shallow water where interactions between sound
Journal of The Acoustical Society of America, 2002
A three-dimensional ocean environment is generated using measured ocean data from the ASIAEX Sout... more A three-dimensional ocean environment is generated using measured ocean data from the ASIAEX South China Sea experiment. The experiment site is characterized as an active internal tide/solibore propagation region along the Northwestern shelf break of the South China Sea. The three-dimensional acoustic effects are studied using a wide-angle version of the parabolic equation code for3d. Mode coupling matrices and horizontal
In this paper, we quantify the dynamical causes and uncertainties of striking differences in acou... more In this paper, we quantify the dynamical causes and uncertainties of striking differences in acoustic transmission data collected on the shelf and shelfbreak in the northeastern Taiwan region within the context of the 2008 Quantifying, Predicting, and Exploiting Uncertainty (QPE 2008) pilot experiment. To do so, we employ our coupled oceanographic (4-D) and acoustic (Nx2-D) modeling systems with ocean data
Passive-phase conjugation (PPC), in a shallow water waveguide, the cross-correlation of impulse r... more Passive-phase conjugation (PPC), in a shallow water waveguide, the cross-correlation of impulse response and the impulse response immediately after, can be utilized as the channel equalizer to enhance the communication performance. PPC is more practical and simpler than Time Reversal Mirror (TRM) since the back propagation is simulated, instead of using source receiver array transmitting backward. This paper addresses the
Journal of The Acoustical Society of America, 2001
Sonar performance can be characterized by its detection range, which is determined by the sonar e... more Sonar performance can be characterized by its detection range, which is determined by the sonar equation. The sonar equation includes parameters of sonar systems, environments, and the detection algorithms. Though the detection algorithm is itself a statistical means, it does not describe the relationship between the statistical properties of the environmental parameters with the detection range. This paper presents a
The developments of marine observatories and automatic sound detection algorithms have facilitate... more The developments of marine observatories and automatic sound detection algorithms have facilitated the long-term monitoring of multiple species of odontocetes. Although classification remains difficult, information on tonal sound in odontocetes (i.e., toothed whales, including dolphins and porpoises) can provide insights into the species composition and group behavior of these species. However, the approach to measure whistle contour parameters for detecting the variability of odontocete vocal behavior may be biased when the signal-tonoise ratio is low. Thus, methods for analyzing the whistle usage of an entire group are necessary. In this study, a local-max detector was used to detect burst pulses and representative frequencies of whistles within 4.5-48 kHz. Whistle contours were extracted and classified using an unsupervised method. Whistle characteristics and usage pattern were quantified based on the distribution of representative frequencies and the composition of whistle repertoires. Based on the one year recordings collected from the Marine Cable Hosted Observatory off northeastern Taiwan, odontocete burst pulses and whistles were primarily detected during the nighttime, especially after sunset. Whistle usage during the nighttime was more complex, and whistles with higher frequency were mainly detected during summer and fall. According to the multivariate analysis, the diurnal variation of whistle usage was primarily related to the change of mode frequency, diversity of representative frequency, and sequence complexity. The seasonal variation of whistle usage involved the previous three parameters, in addition to the diversity of whistle clusters. Our results indicated that the species and behavioral composition of the local odontocete community may vary among seasonal and diurnal cycles. The current monitoring platform facilitates the evaluation of whistle usage based on group behavior and provides feature vectors for species and behavioral classification in future studies.
Theoretical and Computational Acoustics 2005 - Proceedings of the 7th International Conference on ICTCA 2005, 2006
A numerical code using Gaussian Beam Model (NTUGBM) is developed for underwater acoustic propagat... more A numerical code using Gaussian Beam Model (NTUGBM) is developed for underwater acoustic propagation at high frequency (larger than 1 kHz) in oceans with penetrating slope bottom. Several test cases are used to benchmark NTUGBM. Cases include continental shelf and continental slope. The results of NTUGBM are compared with results using EFEPE and FOR3D (Nx2D version). Results of NTUGBM agree
Data analysis and 3D numerical simulations of the acoustic propagation in the ASIAEX SCS experime... more Data analysis and 3D numerical simulations of the acoustic propagation in the ASIAEX SCS experiment are presented in this paper. During the experiment personnel aboard the Taiwanese ocean research vessel, OR3, periodically deployed and towed the J-15-3 acoustic source to study the sound propagation in the ocean. One of the emitted waveforms was continuous wave (CW), which had 5 simultaneous
Background: Zebrafish skin is composed of enveloping and basal layers which form a first-line def... more Background: Zebrafish skin is composed of enveloping and basal layers which form a first-line defense system against pathogens. Zebrafish epidermis contains ionocytes and mucous cells that aid secretion of acid/ions or mucous through skin. Previous studies demonstrated that fish skin is extremely sensitive to external stimuli. However, little is known about the molecular mechanisms that modulate skin cell apoptosis in zebrafish.
Background: Obesity is a complex, multifactorial disorder influenced by the interaction of geneti... more Background: Obesity is a complex, multifactorial disorder influenced by the interaction of genetic, epigenetic, and environmental factors. Obesity increases the risk of contracting many chronic diseases or metabolic syndrome. Researchers have established several mammalian models of obesity to study its underlying mechanism. However, a lower vertebrate model for conveniently performing drug screening against obesity remains elusive. The specific aim of this study was to create a zebrafish obesity model by over expressing the insulin signaling hub of the Akt1 gene.
This document describes data, sensors, and other useful information pertaining to the ONR sponsor... more This document describes data, sensors, and other useful information pertaining to the ONR sponsored QPE field program to quantify, predict and exploit uncertainty in observations and prediction of sound propagation. This experiment was a joint operation between Taiwanese and U.S. researchers to measure and assess uncertainty of predictions of acoustic transmission loss and ambient noise, and to observe the physical oceanography and geology that are necessary to improve their predictability. This work was performed over the continental shelf and slope northeast of Taiwan at two sites: one that was a relatively flat, homogeneous shelf region and a more complex geological site just shoreward of the shelfbreak that was influenced by the proximity of the Kuroshio Current. Environmental moorings and ADCP moorings were deployed and a shipboard SeaSoar vehicle was used to measure environmental spatial structure. In addition, multiple bottom moored receivers and a horizontal hydrophone array were deployed to sample transmission loss from a mobile source and ambient noise. The acoustic sensors, environmental sensors, shipboard resources, and experiment design, and their data, are presented and described in this technical report.
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