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Artykuły w czasopismach na temat "Hydrophone Transfer Function"
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Hull, Andrew J. "A Technique to Measure the Breathing Wave Speed in a Towed Array". Journal of Vibration and Acoustics 116, nr 2 (1.04.1994): 243–45. http://dx.doi.org/10.1115/1.2930419.
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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.
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Wear, Keith A., i Yunbo Liu. "Needle hydrophone transfer function model for characterizing therapeutic transducers". Journal of the Acoustical Society of America 144, nr 3 (wrzesień 2018): 1700. http://dx.doi.org/10.1121/1.5067554.
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Krücker, Jochen F., Alexander Eisenberg, Martin Krix, Ralf Lötsch, Martin Pessel i 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, nr 4 (kwiecień 2000): 1994–2003. http://dx.doi.org/10.1121/1.428483.
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Cheng, S. P., i N. C. Perkins. "Theoretical and Experimental Analysis of the Forced Response of Sagged Cable/Mass Suspensions". Journal of Applied Mechanics 61, nr 4 (1.12.1994): 944–48. http://dx.doi.org/10.1115/1.2901583.
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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.
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Shao, Y., D. Mei, Z. Fan i 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, nr 3 (29.07.2010): 745–53. http://dx.doi.org/10.1243/09544062jmes2119.
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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.
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Oliveira, E. G., J. C. Machado i R. P. B. Costa-Felix. "Hydrophone's sensitivity calibration based on its complex transfer function". Journal of Physics: Conference Series 575 (6.01.2015): 012004. http://dx.doi.org/10.1088/1742-6596/575/1/012004.
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Liu, Kuan-Wen, Ching-Jer Huang, Gee-Pinn Too, Zong-You Shen i Yung-Da Sun. "Underwater Sound Source Localization Based on Passive Time-Reversal Mirror and Ray Theory". Sensors 22, nr 6 (21.03.2022): 2420. http://dx.doi.org/10.3390/s22062420.
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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.
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Xiao, Yan, i Xuesong Zhang. "Method for Establishing a Traveling Wave Sound Field with Adaptive Control in a Water-Filled Sound Tube". Applied Sciences 11, nr 13 (22.06.2021): 5785. http://dx.doi.org/10.3390/app11135785.
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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.
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Javier, Rodrigo F., Ramis Jaime, Poveda Pedro, Carbajo Jesus i Segovia Enrique. "Analysis of the Underwater Radiated Noise Generated by Hull Vibrations of the Ships". Sensors 23, nr 2 (16.01.2023): 1035. http://dx.doi.org/10.3390/s23021035.
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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.
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Saalbach, Kai-Alexander, Jens Twiefel i Jörg Wallaschek. "Self-sensing cavitation detection capability of horn geometries for high temperature application". Journal of Vibroengineering 18, nr 2 (31.03.2016): 989–98. http://dx.doi.org/10.21595/jve.2016.16600.
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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.
Rozprawy doktorskie na temat "Hydrophone Transfer Function"
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Charvolin, Delphine. "Études structurales des protéines de transfert de lipides du mais et du blé : caractérisation de l'interaction entre protéine et lipide". Grenoble 1, 1997. http://www.theses.fr/1997GRE10008.
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Les proteines de transfert de lipide forment une famille de petites proteines, tres abondantes dans les plantes et qui presentent une forte homologie de sequence. Leur fonction est assez mal connue et plusieurs hypotheses ont ete emises: elles peuvent etre des transporteurs de phospholipides membranaires entre les membranes cellulaires, ou bien des transporteurs des monomeres de cutine vers les couches externes des plantes ; elles peuvent jouer un role dans la defense des plantes ou encore participer aux mecanismes de stockage des graisses lors de la maturation des graines. Les structures de la proteine de transfert de lipide du ble en presence de lyso-myristoyl-phosphatidyl-choline et de la proteine de transfert de lipide du mais, en absence de lipide ont ete resolues par diffraction des rayons x, respectivement a 2,6 et 1,9 angstroms de resolution. Les structures obtenues sont proches des autres structures de cette famille, determinees par rmn ou cristallographie: elles sont formees de quatre helices, stabilisees par quatre ponts disulfure. On observe la formation d'une cavite cylindrique allongee au sein de la proteine du mais cristallisee sans lipide: elle mesure environ 20 sur 3 sur 4 angstroms et est formee d'une zone hydrophobe et d'une zone polaire, limitee par une tyrosine et deux arginines. La structure de la proteine du ble cristallisee en presence du lipide met en evidence que la zone hydrophobe de la cavite fixe deux chaines carbonnees de lipide et que la zone polaire fixe vraisemblablement la tete polaire du lipide, les residus tyrosine et arginine jouant probablement un role fondamental dans l'attache de la tete polaire
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Sen, Shoham. "Simulation and Study of Noise Generated due to Turbulent Boundary Layer in Towed Hydrophone Array". Thesis, 2016. https://etd.iisc.ac.in/handle/2005/4331.
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In this thesis, a wave propagation based analytical model is developed for an underwater towed array. The towed array is modeled as an in finite tube filled with a certain liquid and submerged in an in finite volume of water. This tube is excited by turbulent boundary layer (TBL) excitation which is modeled using both the Corcos and the Chase models. The acoustic response (self-noise) of the towed array is found using the transfer function of the tube and the PSD of the turbulent excitation.
The acoustic response spectrum is compared with the results from the literature. This happens to be the main contribution of the work. This is so because very little literature is available on towed arrays. There is only one analytical work available and our results match exactly with theirs. With respect to experimental results, although there are several articles, numerical values of the tube material properties, the fluid properties and the tube dimensions have not been reported in full. This makes the comparison very difficult. Hence, by doing several parametric studies and investigating properties of materials that were applicable like rubber or Nylon, we have managed to narrow down the parameter ranges and made comparisons with the experimental results.
We have matched single hydrophone TBL response with experimental results from two separate groups. We have had to vary several parameter values in order to do this. The parameters include the Young's Modulus, density, Poisson's ratio and the thickness and diameter of the tube. Also included are the density and the speed of sound of the internal fluid. Sometimes a material from a handbook was chosen that gave a set of parameters. After having matched with the experimental values, the idea was to conduct a parametric study to decide the most influential parameters. We have done this using both the dimensional physical variables as well as non-dimensional variables. We nondimensionalized the equations to help reduce the number of variables in the system and then studied the effect that each parameter has on the noise generated due to Turbulent Boundary Layer developed as a result of the tow. The dominant parameter that influences the TBL response at the hydrophone location is the tube radius a, followed by the Young Modulus E, the density of internal fluid pfi and the thickness h of the tube. An increment in a, E and h reduces the TBL response, while an pfi increment in increases the TBL response.
In addition, several analytical studies were conducted to understand the dispersion characteristics of fluid-_filled submerged tubes. This study is presented in the appendix in order to avoid cluttering the main document. The main idea that emerges from this study is that there is a single real wavenumber in this coupled fluid-structure system which responds at its resonance when the TBL spectrum wavenumber matches the wavenumber value. All other free waves are complex and hence under forced excitation, they do not respond.
Streszczenia konferencji na temat "Hydrophone Transfer Function"
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Cintosun, Esen, i Layton Gilroy. "Estimating Ship Underwater Radiated Noise from Onboard Vibrations". W SNAME Maritime Convention. SNAME, 2021. http://dx.doi.org/10.5957/smc-2021-114.
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The acoustic signature of an Orca-class training vessel (Patrol Craft Training, PCT) Moose from the Royal Canadian Navy (RCN) was measured at the RCN’s Patricia Bay acoustic range on Vancouver Island, British Columbia, Canada. The acoustic range trials included accelerometer measurements on the ship hull and in the engine room and hydrophone measurements at approximately 100 m from the ship. The trials were carried out at the ship speed range of 3 to 20 knots. The test data from all the trial runs was used to derive, evaluate and validate the method of estimating ship underwater radiated noise from onboard vibrations. In the investigation, the runs were split into two sets: a training set and a testing set. A least squares approximation, AQV (average quadratic velocity) SL (source level) correlation, was then applied to the training set data to formulate a transfer function to estimate the underwater radiated noise from onboard vibrations. The AQV is calculated from accelerometer measurements (vibration levels) and SL is obtained from the hydrophone measurements. The third octave frequency band (from 10 Hz to 10 kHz) SL estimations of the testing set runs (using the transfer function and AQV) are within 1 to 3 dB of SL from the hydrophone measurements. This study demonstrates a capability of monitoring underwater radiated noise from ships using only onboard vibration levels which may be of interest for future projects relating to the reduction of shipping noise against a threshold in acoustically sensitive environments.
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Cheng, S. P., i N. C. Perkins. "Theoretical and Experimental Analysis of the Forced Response of Sagged Cable/Mass Suspensions". W ASME 1993 Design Technical Conferences. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/detc1993-0173.
Pełny tekst źródłaStreszczenie:
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.
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Alexandrescu, Aurora C., Simona Adina O. Alexandrescu i Constantin Adrian O. Alexandrescu. "Contributions Concerning the Power Optimization of the Pumping Stations". W ASME 2008 Fluids Engineering Division Summer Meeting collocated with the Heat Transfer, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/fedsm2008-55007.
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Profitability of water distribution activity depends largely on the relationships between operational capability and service costs, related to supplier’s performance, volume of distributed water and effective operating costs. The main variables that influence the total selling price are required investment value, specific consumption of electrical energy for pumping power, unit price of the electrical energy and total volume of monthly consumed water billed. The selection of rehabilitation and modernization measures must rely on market studies results that appropriately establish the quantities of water that may be distributed and billed. Present and future water requirements will be determined based on the analysis of actual operation data and on estimation of future trends in water consumption on national and international levels. The optimization calculation will use two target functions: total maximum efficiency and total electric power consumption required for transport of each cubic meter of supplied water, and cubic meter of sewage water, respectively. The mathematical methods may be improved by taking into account all active consumers in the network with simultaneous water requirements, at each moment of the day. Using several original mathematical algorithms, authors developed a computer program that calculates the functional parameters of the ensemble pumping station – hydrophore – pipe distribution network, as well as the available consumer parameters. This may be accomplished at each moment in time, depending on the number of active consumers simultaneously connected to the supply network, in the hypothesis of a minimum price of cubic meter of pumped water. This paper proposes a solution of the problem of reducing production costs for supplied domestic water, which directly affects the reduction of the electric power consumption.