Journal articles: 'Hydrophone Transfer Function'

1

Hull, Andrew J. "A Technique to Measure the Breathing Wave Speed in a Towed Array." Journal of Vibration and Acoustics 116, no. 2 (April 1, 1994): 243–45. http://dx.doi.org/10.1115/1.2930419.

Full text

Abstract:

A method is developed for measuring the breathing wave speed in a towed array. The front of the array is longitudinally vibrated, producing aft-traveling wave energy that is detected by measuring the transfer function of a hydrophone channel and a forward bulkhead-mounted accelerometer. The transfer function is composed of two distinct wave types: an extensional wave and a breathing wave. The breathing wavelengths are much shorter than the extensional wavelengths; therefore, the local minimum associated with the first breathing wave null across the hydrophone channel can be identified. Because the frequency at which this null occurs and the length of the hydrophone channel are known, the breathing wave speed can be calculated.

APA, Harvard, Vancouver, ISO, and other styles

2

Wear, Keith A., and Yunbo Liu. "Needle hydrophone transfer function model for characterizing therapeutic transducers." Journal of the Acoustical Society of America 144, no. 3 (September 2018): 1700. http://dx.doi.org/10.1121/1.5067554.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Krücker, Jochen F., Alexander Eisenberg, Martin Krix, Ralf Lötsch, Martin Pessel, and Hans-Georg Trier. "Rigid piston approximation for computing the transfer function and angular response of a fiber-optic hydrophone." Journal of the Acoustical Society of America 107, no. 4 (April 2000): 1994–2003. http://dx.doi.org/10.1121/1.428483.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Cheng, S. P., and N. C. Perkins. "Theoretical and Experimental Analysis of the Forced Response of Sagged Cable/Mass Suspensions." Journal of Applied Mechanics 61, no. 4 (December 1, 1994): 944–48. http://dx.doi.org/10.1115/1.2901583.

Full text

Abstract:

This study examines the forced response of a sagged elastic cable supporting an array of discrete masses. Such systems arise, for instance, in ocean engineering applications employing cable hydrophone arrays. The excitation considered is harmonic and normal to the cable and may, for instance, approximate prescribed environmental loading. An asymptotic model is presented that describes the linear forced response of a cable/mass suspension having small equilibrium curvature. Closed-form expressions for the Green’s function to an associated boundary value problem are obtained using a transfer matrix formulation. The derived Green’s function is utilized to construct integral representations for steady-state response under boundary and/or domain excitation. Solutions obtained for a variety of domain loading distributions demonstrate the utility and efficiency of this solution strategy. The theoretical response predictions are verified through experimental measurements of the natural frequency spectrum and frequency response of laboratory cable/mass suspensions.

APA, Harvard, Vancouver, ISO, and other styles

5

Shao, Y., D. Mei, Z. Fan, and K. Yang. "A high-precision reconstructing technique for a high-frequency acoustic field based on the angular spectrum method." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, no. 3 (July 29, 2010): 745–53. http://dx.doi.org/10.1243/09544062jmes2119.

Full text

Abstract:

To apply ultrasonic radiation force in precise manipulation for micro-components, a reconstruction technique for low-frequency sound field based on angular spectrum method (ASM) was adopted in the reconstruction for high-frequency sound field, and a high-precision reconstructing technique for high-frequency sound field was developed. First, the principle of reconstructing the sound field by ASM and four key factors on reconstruction precision were analysed. Second, the marginal Gibbs phenomenon and aperture replication effect were decreased by optimizing of the sampling interval and holographical aperture, and the signal-to-noise ratio (SNR) was increased by using the tapered filter to pretreat the signal data in wave number space. Then, the ill-posedness in reverse problem was eliminated by using a new kind of k-space filter to refine the transfer function. Finally, the reconstruction experiment of 1.75 MHz ultrasonic field was conducted by using the three-dimensional precise scanning system and needle-type hydrophone, and the experimental results validate the feasibility and efficiency of the method proposed in this study.

APA, Harvard, Vancouver, ISO, and other styles

6

Oliveira, E. G., J. C. Machado, and R. P. B. Costa-Felix. "Hydrophone's sensitivity calibration based on its complex transfer function." Journal of Physics: Conference Series 575 (January 6, 2015): 012004. http://dx.doi.org/10.1088/1742-6596/575/1/012004.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Liu, Kuan-Wen, Ching-Jer Huang, Gee-Pinn Too, Zong-You Shen, and Yung-Da Sun. "Underwater Sound Source Localization Based on Passive Time-Reversal Mirror and Ray Theory." Sensors 22, no. 6 (March 21, 2022): 2420. http://dx.doi.org/10.3390/s22062420.

Full text

Abstract:

This study investigates the performance of a passive time-reversal mirror (TRM) combined with acoustic ray theory in localizing underwater sound sources with high frequencies (3–7 kHz). The TRM was installed on a floating buoy and comprised four hydrophones. The ray-tracing code BELLHOP was used to determine the transfer function between a sound source and a field point. The transfer function in the frequency domain obtained from BELLHOP was transformed into the time domain. The pressure field was then obtained by taking the convolution of the transfer function in the time domain with the time-reversed signals that were received by the hydrophones in the TRM. The location with the maximum pressure value was designated as the location of the source. The performance of the proposed methodology for source localization was tested in a towing tank and in the ocean. The aforementioned tests revealed that even when the distances between a source and the TRM were up to 1600 m, the distance deviations between estimated and actual source locations were mostly less than 2 m. Errors originated mainly from inaccurate depth estimation, and the literature indicates that they can be reduced by increasing the number of TRM elements and their apertures.

APA, Harvard, Vancouver, ISO, and other styles

8

Xiao, Yan, and Xuesong Zhang. "Method for Establishing a Traveling Wave Sound Field with Adaptive Control in a Water-Filled Sound Tube." Applied Sciences 11, no. 13 (June 22, 2021): 5785. http://dx.doi.org/10.3390/app11135785.

Full text

Abstract:

The transfer function method is a common method for establishing a traveling wave field in a sound tube to measure the reflection and transmission coefficient of underwater material. The voltage applied to the secondary sound source can be calculated in accordance with the transfer matrix between the sound sources and hydrophones, then a traveling wave field can be established in the sound tube. However, the transfer function must be remeasured when the measurement frequency needs to be changed. A checking procedure of the traveling wave field in the sound tube is essential before measuring underwater acoustic material. If it is not an accurate traveling wave field, the secondary sound source signal should be corrected until the traveling wave field meets the requirements. To address these problems, an adaptive control method for generating plane traveling waves is proposed. The phase difference of sound pressures measured using the two hydrophones between the secondary sound source and the sample is used as the objective function in the adaptive algorithm, and the amplitude and phase of the secondary sound source can be obtained using the adaptive control system in the frequency domain. When a traveling wave field is formed, the reflection and transmission coefficient of the sample can be measured at the same time. With this method, the procedure of testing the traveling wave field is omitted. If the state of the primary sound source changes, the signal form of the secondary sound source can be changed immediately. Therefore, the efficiency of material measurement is improved. Theoretically, this method can obtain the most matching signal form of the secondary sound source, such that the accuracy of this method is remarkably high. Simulation and experimental results in this paper show that the measurement accuracy is reliable within the frequency range of 100–2500 Hz.

APA, Harvard, Vancouver, ISO, and other styles

9

Javier, Rodrigo F., Ramis Jaime, Poveda Pedro, Carbajo Jesus, and Segovia Enrique. "Analysis of the Underwater Radiated Noise Generated by Hull Vibrations of the Ships." Sensors 23, no. 2 (January 16, 2023): 1035. http://dx.doi.org/10.3390/s23021035.

Full text

Abstract:

Shipping traffic is recognised as the main man-noise source of the anthropogenic noise generated in the marine environment. The underwater acoustic pollution is increased due to the increment of the human activity at seas supposing a threat for marine habitats. The ship as acoustic source must be understood and controlled to manage the maritime areas both in time and space to reduce the impact of noise in marine fauna. Shipping noise is mainly composed of flow noise, propeller noise and machinery noise. This research is focused on the analysis and estimation of the underwater radiated noise generated by the vibrations of the onboard machinery or structure-borne noise based on the calculation of the transfer function. This function relates the acceleration levels of the vibrations of the hull’s panels and the radiated noise by them using the radiation efficiency. Different analytical methods to estimate the radiation efficiency are presented and compared with data collected at sea. The measurements are performed acquiring simultaneously acceleration and acoustic levels by means on accelerometers installed on the hull’s panels at different positions and hydrophones deployed close to the bow, middle and stern of the ship. The analysis of the transmission of the vibrations along the ships is performed using the data from different locations of the hydrophones. The quality of the measurements is analysed using the coherence function through the spectral correlation between the measurement of vibrations and acoustic levels. On the other hand, signal-to-noise ratio is computed to verify the strength of the noise sources. The computed transfer function is used to predict the underwater radiated noise from vibrations showing differences less than 2 dB re to 1 μPa2.

APA, Harvard, Vancouver, ISO, and other styles

10

Saalbach, Kai-Alexander, Jens Twiefel, and Jörg Wallaschek. "Self-sensing cavitation detection capability of horn geometries for high temperature application." Journal of Vibroengineering 18, no. 2 (March 31, 2016): 989–98. http://dx.doi.org/10.21595/jve.2016.16600.

Full text

Abstract:

Cavitation is utilized in a wide range of applications. As examples ultrasonic cleaning baths and emulsification in sonochemistry may be mentioned. For a high temperature ultrasonic assisted casting process, the authors’ aim is to detect cavitation in the ongoing process using cavitation noise spectra without additional sensors like hydrophones, which disturb the sound field. The authors’ aim is to detect cavitation from the ultrasonic transducers’ current signal. Two different horn geometries are tested for their cavitation detection capability. To investigate the frequency components in the transducers’ current signal without the influence of the horns’ individual transfer functions, the measured data are processed to obtain the uninfluenced signals. Different frequency components are found in the measurements, which can be used as indicators for cavitation.

APA, Harvard, Vancouver, ISO, and other styles

11

Wear, Keith A. "Considerations for Choosing Sensitive Element Size for Needle and Fiber-Optic Hydrophones—Part I: Spatiotemporal Transfer Function and Graphical Guide." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 66, no. 2 (February 2019): 318–39. http://dx.doi.org/10.1109/tuffc.2018.2886067.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Larkin, Christopher, Rembrandt J. F. Haft, Matthew J. Harley, Beth Traxler, and Joel F. Schildbach. "Roles of Active Site Residues and the HUH Motif of the F Plasmid TraI Relaxase." Journal of Biological Chemistry 282, no. 46 (September 20, 2007): 33707–13. http://dx.doi.org/10.1074/jbc.m703210200.

Full text

Abstract:

Bacterial conjugation, transfer of a single strand of a conjugative plasmid between bacteria, requires sequence-specific single-stranded DNA endonucleases called relaxases or nickases. Relaxases contain an HUH (His-hydrophobe-His) motif, part of a three-His cluster that binds a divalent cation required for the cleavage reaction. Crystal structures of the F plasmid TraI relaxase domain, with and without bound single-stranded DNA, revealed an extensive network of interactions involving HUH and other residues. Here we study the roles of these residues in TraI function. Whereas substitutions for the three His residues alter metal-binding properties of the protein, the same substitution at each position elicits different effects, indicating that the residues contribute asymmetrically to metal binding. Substitutions for a conserved Asp that interacts with one HUH His demonstrate that the Asp modulates metal affinity despite its distance from the metal. The bound metal enhances binding of ssDNA to the protein, consistent with a role for the metal in positioning the scissile phosphate for cleavage. Most substitutions tested caused significantly reduced in vitro cleavage activities and in vivo transfer efficiencies. In summary, the results suggest that the metal-binding His cluster in TraI is a finely tuned structure that achieves a sufficient affinity for metal while avoiding the unfavorable electrostatics that would result from placing an acidic residue near the scissile phosphate of the bound ssDNA.

APA, Harvard, Vancouver, ISO, and other styles

13

Dosso, Stan, and Dag Tollefsen. "Quantifying and transferring environmental uncertainties in underwater acoustic modeling." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A66—A67. http://dx.doi.org/10.1121/10.0010681.

Full text

Abstract:

Uncertainties in environmental inputs represent a major source of uncertainty in underwater acoustic model outputs and applications thereof (e.g., transmission-loss estimation, source localization). Seabed geoacoustic parameters are often estimated by the inversion of ocean acoustic data. Hence, rigorous quantification of geoacoustic inversion uncertainties and the transfer of these uncertainties to modeling applications are of key importance. Uncertainty estimation in geoacoustic inversion is naturally accommodated in a Bayesian formulation, which combines data and prior information to form the posterior probability density (PPD) of seabed parameters. Important components of this approach include quantitative model selection for seabed parameterizations consistent with the information content of the data; an appropriate model for residual data errors that specifies the likelihood function; and nonlinear estimation of the PPD, which is normally carried out using Markov-chain Monte Carlo (MCMC) methods. MCMC characterizes the PPD using a large ensemble of dependent random samples of the geoacoustic parameters, which can be computationally demanding. However, these uncertainties can be transferred efficiently to subsequent propagation-modeling applications using a much-smaller, randomly chosen (independent) subset from the ensemble. The approach is illustrated using simulations and inversion of ship noise recorded on a horizontal array of hydrophones at the New England Mud Patch.

APA, Harvard, Vancouver, ISO, and other styles

14

Rodrigo, Maria A. "Wetland Restoration with Hydrophytes: A Review." Plants 10, no. 6 (May 21, 2021): 1035. http://dx.doi.org/10.3390/plants10061035.

Full text

Abstract:

Restoration cases with hydrophytes (those which develop all their vital functions inside the water or very close to the water surface, e.g., flowering) are less abundant compared to those using emergent plants. Here, I synthesize the latest knowledge in wetland restoration based on revegetation with hydrophytes and stress common challenges and potential solutions. The review mainly focusses on natural wetlands but also includes information about naturalized constructed wetlands, which nowadays are being used not only to improve water quality but also to increase biodiversity. Available publications, peer-reviewed and any public domain, from the last 20 years, were reviewed. Several countries developed pilot case-studies and field-scale projects with more or less success, the large-scale ones being less frequent. Using floating species is less generalized than submerged species. Sediment transfer is more adequate for temporary wetlands. Hydrophyte revegetation as a restoration tool could be improved by selecting suitable wetlands, increasing focus on species biology and ecology, choosing the suitable propagation and revegetation techniques (seeding, planting). The clear negative factors which prevent the revegetation success (herbivory, microalgae, filamentous green algae, water and sediment composition) have to be considered. Policy-making and wetland restoration practices must more effectively integrate the information already known, particularly under future climatic scenarios.

APA, Harvard, Vancouver, ISO, and other styles

15

Tubiana, Thibault, Ian Sillitoe, Christine Orengo, and Nathalie Reuter. "Dissecting peripheral protein-membrane interfaces." PLOS Computational Biology 18, no. 12 (December 14, 2022): e1010346. http://dx.doi.org/10.1371/journal.pcbi.1010346.

Full text

Abstract:

Peripheral membrane proteins (PMPs) include a wide variety of proteins that have in common to bind transiently to the chemically complex interfacial region of membranes through their interfacial binding site (IBS). In contrast to protein-protein or protein-DNA/RNA interfaces, peripheral protein-membrane interfaces are poorly characterized. We collected a dataset of PMP domains representative of the variety of PMP functions: membrane-targeting domains (Annexin, C1, C2, discoidin C2, PH, PX), enzymes (PLA, PLC/D) and lipid-transfer proteins (START). The dataset contains 1328 experimental structures and 1194 AphaFold models. We mapped the amino acid composition and structural patterns of the IBS of each protein in this dataset, and evaluated which were more likely to be found at the IBS compared to the rest of the domains’ accessible surface. In agreement with earlier work we find that about two thirds of the PMPs in the dataset have protruding hydrophobes (Leu, Ile, Phe, Tyr, Trp and Met) at their IBS. The three aromatic amino acids Trp, Tyr and Phe are a hallmark of PMPs IBS regardless of whether they protrude on loops or not. This is also the case for lysines but not arginines suggesting that, unlike for Arg-rich membrane-active peptides, the less membrane-disruptive lysine is preferred in PMPs. Another striking observation was the over-representation of glycines at the IBS of PMPs compared to the rest of their surface, possibly procuring IBS loops a much-needed flexibility to insert in-between membrane lipids. The analysis of the 9 superfamilies revealed amino acid distribution patterns in agreement with their known functions and membrane-binding mechanisms. Besides revealing novel amino acids patterns at protein-membrane interfaces, our work contributes a new PMP dataset and an analysis pipeline that can be further built upon for future studies of PMPs properties, or for developing PMPs prediction tools using for example, machine learning approaches.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Hydrophone Transfer Function'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles